Title:
Coupling of reinforcing fibres to resins in curable composites
Kind Code:
A1


Abstract:
A method for preparing a moulded composite comprises milling reinforcing fibres to a mean fibre length of less than 5 mm, treating the milled fibres with a coupling agent and suspending the dried fibres in a liquid resin which reacts with the coupling agent on the fibres. Preferred fibres include glass fibres and milled mica coated with calcined iron oxide. Preferred coupling agents are organosilanes and metal acrylates e.g. zinc diacrylate. Composites formed by the above method exhibit improved impact resistance, tensile strength and flexural strength.



Inventors:
Hodgson, Peter Clifford (New South Wales, AU)
Application Number:
10/416843
Publication Date:
12/01/2005
Filing Date:
11/16/2001
Primary Class:
International Classes:
C08J5/24; B29C39/02; C08K7/02; B29K105/08; (IPC1-7): D04H1/00
View Patent Images:



Foreign References:
JPH10273555A1998-10-13
Other References:
JP10-273555, KAGEYAMA et al., 1998, machine translation
Ishida, et al., "Effect of Hydrolysis and Drying on the Siloxane Bonds of a Silane Coupling Agent Deposited on E-Glass Fibers"; Journal of Polymer Science, Polymer Physics Ed. Vol 18, pp.233-237; (1980)
DiBenedetto, "Tailoring of interfaces in glass fiber reinforced polymer composites: a review"; Materials Science and Engineering, A302, (2001), pp. 74-82
Primary Examiner:
GRAY, JILL M
Attorney, Agent or Firm:
BakerHostetler (Philadelphia, PA, US)
Claims:
1. A reinforcing fibre having a surface with substantially no sizing agent thereon, wherein the surface of the fibre is substantially coated with a coupling agent for coupling said fibre with a resin when cured.

2. A reinforcing fibre as claimed in claim 1, which is substantially inorganic and which is suitable for use with a resin which is substantially organic, the coupling agent comprising a plurality of molecules each having a first end adapted to bond to the fibre and a second end which is adapted to bond to the resin.

3. A reinforcing fibre as claimed in claim 1 or claim 2, wherein said coupling agent has been selected from the group consisting of a polymerisable coupling agent and a coupling agent which has been at least partially polymerised before application thereof to the fibre.

4. A reinforcing fibre as claimed in claim 3, wherein the coupling agent is a non-polymerised polymerisable coupling agent.

5. A reinforcing fibre as claimed in claim 3 or claim 4, wherein said coupling agent has been at least partially polymerised after application thereof to the fibre.

6. A reinforcing fibre as claimed in claim 5, wherein said coupling agent has been at least partially polymerised in the presence of additional polymerisable coupling agent.

7. A reinforcing fibre as claimed in any one of claims 1 to 6, wherein at least one of the fibre, the resin and the coupling agent have been selected so as to yield a composite of high impact resistance.

8. A reinforcing fibre as claimed in any one of claims 1 to 7, wherein at least one of the fibre, the resin and the coupling agent have been selected so as to yield a composite of high tensile strength.

9. A reinforcing fibre as claimed in any one of claims 1 to 8, wherein at least one of the fibre, the resin and the coupling agent have been selected so as to yield a composite of high flexural strength.

10. A reinforcing fibre as claimed in any one of claims 1 to 9, wherein the coupling agent has been selected from the group consisting of a silane, an organic metal ligand and combinations thereof.

11. A reinforcing fibre as claimed in claim 10, wherein the coupling agent is a titanate, a zirconate or a combination thereof.

12. A reinforcing fibre, wherein said fibre has a surface which is substantially coated with a coupling agent for coupling said fibre with a substantially organic resin wren cured, said coupling agent being at least partially polymerised.

13. A reinforcing fibre as claimed in claim 12, wherein the coupling agent has been selected from the group consisting of a polymerised or partially polymerised silane, a polymerised or partially polymerised organic metal ligand and combinations thereof.

14. A reinforcing fibre as claimed in any one of claims 1 to 13, wherein the surface of the fibre has been pre-treated with a metal oxide before application of the coupling agent thereto.

15. A reinforcing fibre as claimed in claim 14, wherein the metal oxide is selected from iron (III) oxide, iron (II) oxide, titanium dioxide, tungsten oxide, hafnium dioxide, nickel oxide, cobalt oxide, manganese dioxide, chromium trioxide, vanadium pentoxide, zinc oxide, molybdenum trioxide, tin dioxide, indium trioxide, niobium pentoxide, tantalum pentoxide and zirconium dioxide.

16. A process for making a reinforcing fibre suitable for use in reinforcing a composite made of the fibre and a resin, said process including the step of substantially removing any sizing agent previously applied to the surface of the reinforcing fibre.

17. A process for making a reinforcing fibre as claimed in claim 16, said process including the additional step of substantially coating the surface of the fibre with a coupling agent for coupling said fibre to said resin

18. A process for making a reinforcing fibre as claimed in claim 16 or claim 17, wherein the fibre is substantially inorganic and the resin is substantially organic, and the coupling agent comprises a plurality of molecules each having a first end which is adapted to bond to the fibre and a second end which is adapted to bond to the resin.

19. A process for making a reinforcing fibre as claimed in claim 18, wherein said coupling agent has been selected from the group consisting of a polymerisable coupling agent and a coupling agent which is at least partially polimerised.

20. A process for making a reinforcing fibre as claimed in claim 19, wherein the coupling agent is a polymerisable coupling agent that has been allowed to at least partially polymerise in the presence of additional coupling agent.

21. A process for making a reinforcing fibre as claimed in claim 20, wherein the coupling agent has been selected from the group consisting of an unpolymerised or partially polimerised silane, an unpolymerised or partially polimerised organic metal ligand and combinations thereof.

22. A process for making a reinforcing fibre as claimed in claim 21, wherein the organic metal ligand is a titanate, a zirconate or a combination thereof.

24. A process for making a reinforcing fibre as claimed in 16 to 22, wherein the surface of the fibre has been pre-treated with a metal oxide after removal of the sizing agent but before application of the coupling agent thereto.

25. A process for making a reinforcing fibre as claimed claim 24, wherein the metal oxide is selected from iron (III) oxide, iron (II) oxide, titanium dioxide, tungsten oxide, hafnium dioxide, nickel oxide, cobalt oxide, manganese dioxide, chromium trioxide, vanadium pentoxide, zinc oxide, molybdenum trioxide, tin dioxide, indium trioxide, niobium pentoxide, tantalum pentoxide and zirconium dioxide.

26. A reinforcing fibre for a curable resin made by the process according to any one of claims 16 to 25,

27. A cured composite comprising a cured resin incorporating a plurality of reinforcing fibres, at least a portion of said reinforcing fibres having a surface from which sizing agent has been substantially removed.

28. A cured composite as claimed in claim 27, wherein at least a portion of said reinforcing fibres has a surface which is substantially coated with a coupling agent for coupling said fibre with said resin.

29. A cured composite as claimed in claim 28, wherein said coupling agent has been selected from the group consisting of a polymerisable coupling agent and a coupling agent which has been at least partially polimerised.

30. A cured composite as claimed in claim 28 or claim 29, wherein the fibre is substantially inorganic and the resin is substantially organic, and the coupling agent comprises a plurality of molecules each having a first end adapted to bond to the fibre and a second end which is adapted to bond to the resin.

31. A cured composite as claimed in any one of claims 29 or 30, wherein the coupling agent is a coupling agent which has been at least partially polymerised.

32. A cured composite as claimed in any one of claims 29 or 30, wherein the coupling agent is a polymerisable coupling agent.

33. A cured composite as claimed in claim 32, wherein the coupling agent has been selected from the group consisting of a silane, an organic metal ligand and combinations thereof.

34. A cured composite as claimed in claim 33, wherein the coupling agent is a titanate, a zirconate or a combination thereof.

35. A cured composite as claimed in any one of claims 32 to 34, wherein the coupling agent was at least partially polymerised after application thereof to the reinforcing fibre, but before polymerisation of the resin.

36. A cured composite as claimed in claim 31, wherein the coupling agent has been selected from the group consisting of a polymerised or partially polimerised silane, a polymerised or partially polimerised organic metal ligand and combinations thereof.

37. A cured composite as claimed in any one of claims 27 to 36, wherein the surface of the fibre has been pre-treated with a metal oxide before application of the coupling agent thereto.

38. A reinforcing fibre as claimed in claim 37, wherein the metal oxide is selected from iron (III) oxide, iron (I) oxide, titanium dioxide, tungsten oxide, hafnium dioxide, nickel oxide, cobalt oxide, manganese dioxide, chromium trioxide, vanadium pentoxide, zinc oxide, molybdenum trioxide, tin dioxide, indium trioxide, niobium pentoxide, tantalum pentoxide and zirconium dioxide.

39. A curable composite comprising a curable resin incorporating a plurality of reinforcing fibres, at least a portion of said reinforcing fibres having a surface which is substantially free of sizing agent.

40. A curable composite as claimed in claim 39, in which at least a portion of said fibres are substantially coated with a coupling agent for coupling said fibres with the resin when cured.

41. A curable composite as claimed in claim 40, wherein said coupling agent has been selected from the group consisting of a polymerisable coupling agent and a coupling agent which is at least partially polymerised.

42. A curable composite as claimed in claim 40 or claim 41, wherein the fibres are substantially inorganic and the resin is substantially organic, and the coupling agent comprises a plurality of molecules each having a first end adapted to bond to the fibres and a second end which is adapted to bond to the resin.

43. A curable composite as claimed in claim 41 or claim 42, wherein the coupling agent is at least partially polimerised before application thereof to the reinforcing fibres.

44. A curable composite as claimed in claim 41 or claim 42, wherein the coupling agent has been polymerised, at least partially, after application thereof to the reinforcing fibres.

45. A curable composite as claimed in any one of claims 40 to 44, wherein the coupling agent has been selected from the group consisting of a silane, an organic metal ligand and combinations thereof.

46. A curable composite as claimed in claim 45, wherein the coupling agent is a titanate, a zirconate or a combination thereof.

47. A curable composite as claimed in any one of claims 40 to 46, wherein the surface of the fibre has been pre-treated with a metal oxide before application of the coupling agent thereto.

48. A curable composite as claimed in claim 47, wherein the metal oxide is selected from iron (III) oxide, iron (II) oxide, titanium dioxide, tungsten oxide, hafnium dioxide, nickel oxide, cobalt oxide, manganese dioxide, chromium trioxide, vanadium pentoxide, zinc oxide, molybdenum trioxide, tin dioxide, indium trioxide, niobium pentoxide, tantalum pentoxide and zirconium dioxide.

49. A process for making a cured composite including the steps of: preparing a curable composite by combining a curable resin and a plurality of reinforcing fibres, at least a portion of said reinforcing fibres having a surface from which substantially all sizing agent has been removed; and curing said curable composite.

50. A process for making a cured composite as claimed in claim 49, wherein at least a portion of the fibres have a surface which is substantially coated with a coupling agent fox coupling said fibre with the resin when cured.

51. A process for making a cured composite as claimed in claim 49 or claim 50, wherein said coupling agent is selected from the group consisting of a polymerisable coupling agent and a polymerised coupling agent.

52. A process for making a cured composite as claimed in claim 51, wherein said coupling agent is a polymerisable coupling agent.

53. A process for making a cured composite as claimed in any one of claims 50 to 52, wherein the fibres are substantially inorganic and the resin is substantially organic, and the coupling agent comprises a plurality of molecules each having a first end adapted to bond to the fibres and a second end which is adapted to bond to the resin.

54. A process for making a cured composite as claimed in any one of claims 50 to 53, wherein the coupling agent is at least partially polimerised before application thereof to the reinforcing fibres.

55. A process for making a cured composite as claimed in any one of claims 50 to 53, wherein the coupling agent has been polymerised, at least partially, after application thereof to the reinforcing fibres.

56. A process for making a cured composite as claimed in any one of claims 50 to 55, wherein the coupling agent has been selected from the group consisting of a silane, an organic metal ligand and combinations thereof.

57. A process for making a cured composite as claimed in claim 56, wherein the coupling agent is a titanate, a zirconate or a combination thereof.

58. A process for making a cured composite as claimed in any one of claims 50 to 57, wherein the surface of the fibre has been pre-treated with a metal oxide before application of the coupling agent thereto.

59. A process for making a cured composite as claimed in claim 58, wherein the metal oxide is selected from iron (III) oxide, iron (II) oxide, titanium dioxide, tungsten oxide, hafnium dioxide, nickel oxide, cobalt oxide, manganese dioxide, chromium trioxide, vanadium pentoxide, zinc oxide, molybdenum trioxide, tin dioxide, indium trioxide, niobium pentoxide, tantalum pentoxide and zirconium dioxide.

60. A method of applying a composite to a surface, said method comprising: preparing a curable composite by combining a curable resin and a plurality of reinforcing fibres at least a portion of said reinforcing fibres having a surface from which substantially all sizing agent has been removed; applying the curable composite to the surface; and curing said curable composite.

61. A method of applying a composite to a surface as claimed in claim 60, in which at least a portion of the reinforcing fibres has a surface which is substantially coated with a coupling agent before the composite is prepared.

62. A method of applying a composite to a surface as claimed in claim 61, wherein said coupling agent is selected from the group consisting of a polymerisable coupling agent and a polymerised coupling agent.

63. A method of applying a composite to a surface as claimed in claim 61 or 62, wherein the fibres are substantially inorganic and the resin is substantially organic, and the coupling agent comprises a plurality of molecules each having a first end adapted to bond to the fibres and a second end which is adapted to bond to the resin.

64. A method of applying a composite to a surface as claimed in any one of claims 61 to 63, wherein the coupling agent is at least partially polimerised before application thereof to the reinforcing fibres.

65. A method of applying a composite to a surface as claimed in any one of claims 61 to 63, wherein the coupling agent has been polymerised, at least partially, after application thereof to the reinforcing fibres.

66. A method of applying a composite to a surface as claimed in any one of claims 61 to 65, wherein the coupling agent has been selected from the group consisting of a silane, an organic metal ligand and combinations thereof.

67. A method of applying a composite to a ice as claimed in claim 66, wherein the coupling agent is a titanate, a zirconate or a combination thereof.

68. A method of applying a composite to a surface as claimed in any one of claims 60 to 67, wherein the surface of the fibre has been pre-treated with a metal oxide before application of the coupling agent thereto.

69. A method of applying a composite to a surface as claimed in claim 68, wherein the metal oxide is selected from iron (III) oxide, iron (II) oxide, titanium dioxide, tungsten oxide, hafnium dioxide, nickel oxide, cobalt oxide, manganese dioxide, chromium trioxide, vanadium pentoxide, zinc oxide, molybdenum trioxide, tin dioxide, indium trioxide, niobium pentoxide, tantalum pentoxide and zirconium dioxide.

70. A method of applying a composite to a surface as claimed in any one of claims 60 to 69, wherein the step of applying the curable composite to the surface is selected from painting, pumping, brushing, wiping, streaking, pouring, rolling, spreading or other suitable applying methods used in fibreglass fabrication.

71. A method of applying a composite to a surface as claimed in any one of claims 60 to 70, wherein the fibres have a mean length of less than about 4 mm and the composite is applied to the surface by spraying.

72. A method of applying a composite to a surface as claimed in claim 71, wherein the fibres have a mean length of about 3 mm.

73. A method of applying a composite to a surface as claimed in claim 71, wherein the fibres have a maximum mean length of about 3 mm.

74. A cured composite produced by the process according to any one of claims 49 to 59.

75. A cured composite as claimed in claim 75, wherein the fibres have a maximum mean length of less than about 4 mm.

76. A cured composite as claimed in claim 75, wherein the fibres have a mean length of less than about 3 mm.

77. A cured composite as claimed in claim 76, wherein the fibres have a maximum mean length of under 1 mm.

78. A method of moulding a composite, said method comprising: preparing a curable composite by combining a curable resin and a plurality of reinforcing fibres, at least a portion of said fibres having a surface from which substantially all sizing agent has been removed; locating the curable composite in a mould; and curing said curable composite in the mould.

79. A method of moulding a composite as claimed in claim 78, wherein at least a portion of said reinforcing fibres has a surface which has been coated with a coupling agent.

80. A method of moulding a composite as claimed in claim 79, wherein the coupling agent has been selected from the group consisting of a polymerisable coupling agent and a polymerised coupling agent.

81. A method of moulding a composite as claimed in claim 79 or claim 80, wherein the fibres are substantially inorganic and the resin is substantially organic, and the coupling agent comprises a plurality of molecules each having a first end adapted to bond to the fibres and a second end which is adapted to bond to the resin.

82. A method of moulding a composite as claimed in any one of claims 79 to 81, wherein the coupling agent is at least partially polimerised before application thereof to the reinforcing fibres.

83. A method of moulding a composite as claimed in any one of claims 79 to 81, wherein the coupling agent has been polymerised, at least partially, after application thereof to the reinforcing fibres.

84. A method of moulding a composite as claimed in any one of claims 79 to 83, wherein the coupling agent has been selected from the group consisting of a silane, an organic metal ligand and combinations thereof.

85. A method of moulding a composite as claimed in claim 84, wherein the coupling agent is a titanate, a zirconate or a combination thereof.

86. A method of moulding a composite as claimed in any one of claims 78 to 85, wherein the surface of the fibre has been pre-treated with a metal oxide before application of the coupling agent thereto.

87. A method of moulding a composite as claimed in claim 86, wherein the metal oxide is selected from iron (III) oxide, iron (II) oxide, titanium dioxide, tungsten oxide, hafnium dioxide, nickel oxide, cobalt oxide, manganese dioxide, chromium trioxide, vanadium pentoxide, zinc oxide, molybdenum trioxide, tin dioxide, indium trioxide, niobium pentoxide, tantalum pentoxide and zirconium dioxide.

88. A method of moulding a composite as claimed in any one of claims 78 to 87, wherein the fibres have a mean length of less than about 4 mm and the composite is applied to the surface by spraying.

89. A method of moulding a composite as claimed in claim 88, wherein the fibres have a mean length of about 3 mm.

90. A method of moulding a composite as claimed in claim 89, wherein the fibres have a maximum mean length of about 3 mm.

91. A method of moulding a composite as claimed in any one of claims 78 to 90, wherein the step of locating the curable composite in the mould comprises pumping it, pouring it or otherwise placing it in the mould.

92. A method of moulding a composite as claimed in claim 91, wherein the moulding process involves injection moulding and the step of locating the curable composite in the mould comprises injecting the curable composite into the mould.

93. A method of moulding a composite as claimed in any one of claims 78 to 92, wherein the composite comprises an organic thixotrope.

94. A method of moulding a composite as claimed in claim 93, wherein the organic thixotrope is selected from an amide and a glyceryl stearate.

95. A method of moulding a composite as claimed in any one of claims 78 to 94, wherein the resin is selected from Eterset 2504 PT orthophthalic ethylene glycol fumaric acid resin, Eterset 2597 PT orthophthalic ethylene glycol fumaric acid resin, NAN YAR LAI 11 orthophthalic ethylene glycol fumaric acid resin and combinations thereof.

96. A method of moulding a composite as claimed in any one of claims 78 to 95, wherein the fibre material is selected from milled glass fibre, an aramid fibre, a Wollastonite fibre, a nylon fibre, a calcined mica, a surface treated mica and combinations thereof.

97. A method of moulding a composite as claimed in any one of claims 78 to 96, wherein the reinforcing fibre material is selected from the group consisting of surface treated mineral fibres such as Wollastonite, and ceramic fibres such as glass fibres, surface treated synthetic fibres, surface treated aramid fibres, mylar fibre&, nylon fibres, linear polyethylenes, linear polypropylenes, polyesters and carbon fibres.

98. A method of moulding a composite as claimed in any one of claims 78 to 97, wherein the composite comprises a filler selected from Zenospheres, PVC powder, treated organo clays and combinations thereof.

99. A method of moulding a composite as claimed in any one of claims 78 to 98, wherein the coupling agent is selected from a silane having an acrylic functional group, a silane having a vinyl functional group, a silane having a styrene functional group, zinc diacrylate, and combinations thereof.

100. A method of moulding a composite as claimed in any one of claims 78 to 99, wherein the coupling agent is allowed to partially polymerise in aqueous solution prior to coupling thereof to the surface of the fibre and further polymerisation thereon.

101. A method of moulding a composite as claimed in claim 100, wherein the pH of the aqueous solution is raised to more than 7.

102. A method of moulding a composite as claimed in claim 101, wherein the resin has an elongation at break of greater than 6%.

103. A method of moulding a composite as claimed in claim 102, wherein the resin has an elongation at break of greater than 10%.

104. A method of moulding a composite as claimed in claim 102 or claim 103, wherein the resin is selected from the group consisting of epoxy vinyl ester resins, tough vinyl functional urethane resins, tough vinyl functional acrylic resins, and non plasticised flexible polyester resins.

105. A method of moulding a composite as claimed in any one of claims 78 to 104, wherein the composite comprises from 0% to 50% by weight of reinforcing fibres.

106. A product including a reinforcing fibre, a process for making a reinforcing fibre, a process for making a plurality of reinforcing fibres, a reinforcing fibre for a curable resin made by the process of the invention, a cured composite, a curable composite, a process for making a curable composite, a method of applying a composite to a surface and a method of moulding a composite. The uniqueness of this invention has to do with the manufacture and the nature of the fibre reinforcement, the nature of the resins used, the way in which the fibres are mixed into the resin and processes for applying the composite to a mould. The composite formed as a result of adding the short fibre reinforcement improves the impact resistance, the tensile strength flexural strength of the cured composite, substantially simplifies the moulding process, increasing productivity and reducing or eliminating VOCs in the fabrication shop.

107. A product according to claim 106 which is able to be sprayed onto a mould or injected into a mould.

108. A product according to claim 106 which when sprayed onto an open mould does not require mechanical consolidation or when injected into a closed mould does not require any additional fibre reinforcement.

109. A product according to claim 106 which when sprayed onto an open mould does not require mechanical consolidation to optimise the properties of the composite.

110. A method for preparing a product according to claim 106 in which the reinforcing fibre is milled so that the mean fibre length is less than 5 mm. These fibres are te treated with a coupling agent, dissolved m a suitable solvent. The fibres are agitated in suspension in the coupling agent solution for a period of hours so that the entire surface of the fibres are coated in the coupling agent. The fibres are then filtered and dried. They are then sieved to break up agglomerates. The dried sieved fibres are then added to a liquid resin so that all the fibres are wetted individually, without incorporating air. The liquid resin is formulated so that it can react chemically with the coupling agent on the fibres. The product is then catalysed, applied to a mould and allowed to cure.

111. A method according to claim 110 in which the reinforcing fibres are glass fibres, which are free of all surface pre treatment. These fibres are preferably milled so that they have a mean fibre length of approximately 3 mm with less than 1% fibres greater than 4 mm. An organo functional silane is then dissolved in water at pH of 3 and at a concentration of less than 1%. The preferred organo functional silanes are hose that contain a carbon double bond in their structure. The fibres are then added to the solution and agitated in the suspension for a period of hours so that all the available surface of the fibre is coated with the silane. Optionally the pH can be raised after this period to between pH 7 and pH 10 so that the remaining silane molecules in solution will react with the bound silanes to produce silanol oligomers. The fibres are then on the surface of the fibres, filtered from solution and dried. They are then sieved to break up agglomerates and suspended in suitable liquid resins such as unsaturated polyester resins, vinyl ester resins, acrylic resins, vinyl functional resins and combinations. The liquid resin is formulated so that it can react chemically with the coupling agent on the fibres. The product is then applied to a mould and allowed to cure.

112. A process made in accordance with claim 111 except the fibre is milled mica which has been coated with calcined iron oxide prior to the application of silane coupling agents.

113. A process made in accordance with claim 110 where the fibres are synthetic fibres such as nylons, aramid fibres, PET fibres, polyester fibres surface treated linear polyethylene fibres. The coupling agent in these cases is a metal acrylate capable of forming chemical bonds to the surface of the fibres. An example is zinc diacrylate.

114. A process made in accordance with claim 106, 107, 108, 109, 110, 111 where the polymerisable resin is a resin with an elongation at break greater than 10%. These are the preferred resins because they produce products with superior physical properties.

Description:

TECHNICAL FIELD

This invention relates to a reinforcing fibre, a process for making a reinforcing fibre, a process for making a plurality of reinforcing fibres, a reinforcing fibre for a curable resin made by the process of the invention, a cured composite, a curable composite, a process for making a cured composite, a method of applying a composite to a surface, and a method of moulding a composite.

BACKGROUND ART

When fibre reinforced vinyl functional/free radical initiated resins such as Unsaturated Polyester or Vinyl Ester resins are applied to an open mould, they require mechanical consolidation to remove entrapped air. There are two reasons for removing air. The first is to optimize the mechanical strength of the composite, and the second is to improve the chemical resistance. This is also true for epoxy resin composite laminates.

The present art is to

1. spray chopped glass rovings into the resin fan before deposition, or

2. to apply sheets of fabric reinforcement to the mould and then to wet these out with resin, or

3. to pre impregnate the fabric reinforcement with resin prior to placing it on the mould.

All these procedures require some form of mechanical consolidation of the applied laminate to remove entrapped air.

In the current art it is not desirable that the fibres are intimately bonded to the resin matrix. All that is required is that there is sufficient bonding so that the applied stresses can be transmitted to the fibres.

A large proportion of the fibres are held in position by mechanical friction. They are free to slide relative to the resin matrix when the composite is strained sufficiently. One can hear this slipping with the aid of a microphone. When the composite ruptures there are an abundance of fibres protruding from the ruptured surfaces. The sizing on glass rovings interferes with glass to matrix bonding.

The reason the current art performs is due largely to the length of the fibres. Typically fibre length ranges from 12 mm to tens of meters in the case of filament winding and pultrusion and woven rovings. If one hammer mills these reinforcements to less than 4 mm and incorporates them into a UPE or VE laminating resin by conventional processes the resulting composite has poor physical properties.

Typically tensile strength is bellow 65 MPa and it has minimal resistance to crack propagation.

The tensile strength of the resin matrix is greater than the tensile strength of the composite.

This comes about by the fact that the reinforcement is too short to be mechanically locked into the matrix. There is little resistance to crack propagation and such composites are not only weak but are also brittle and have very poor impact resistance.

In the literature there is mentioned the CRITICAL LENGTH of a fibre incorporated in a composite. For fibreglass, the critical length is about 2 mm +-1 mm. The critical length is the minimum length of a bonded fibre that will break in a composite due to applied strain.

Crack propagation in short fibre composites is a problem, because using standard laminating resins stress fields are very concentrated. When rupture occurs in brittle matrix short fibre composites the component suffers brittle failure, the part having poor impact resistance.

In Summary

1. The current surface treatment of fibres is inadequate for short fibre composites.

2. Brittle laminating resins do not provide adequate impact resistance.

3. For optimum chemical/environmental resistance non air inhibited resins are preferred for method 2 composites.

Objects of the Invention

Objects of this invention include providing a reinforcing fibre, a process for making a reinforcing fibre, a process for making a plurality of reinforcing fibres, a reinforcing fibre for a curable resin made by the process of the invention, a cured composite, a curable composite, a process for making a cured composite, a method of applying a composite to a surface, and a method of moulding a composite.

Disclosure of Invention

According to one embodiment of this invention there is provided a reinforcing fibre, wherein

said fibre has a surface which is substantially coated with a coupling agent for coupling said fibre with a resin when cured so as to improve impact resistance, tensile strength, and flexural strength of a cured composite comprising said resin when cured, said coupling agent being selected from the group consisting of a polymerizable coupling agent and a polymerized coupling agent and said cured composite further comprising a plurality of said fibres coated with the polymerized coupling agent incorporated in said cured resin.

In one particular form there is provided a reinforcing fibre, wherein

said fibre has a surface which is substantially coated with a polymerized coupling agent for coupling said fibre with a resin when cured so as to improve impact resistance, tensile strength and flexural strength of a cured composite comprising said resin when cured and said polymerized coupling agent incorporated in said cured resin.

According to another embodiment of this invention there is provided a process for making a reinforcing fibre, said process comprising:

substantially coating the surface of the fibre with a polymerizable coupling agent for coupling said fibre to a resin so as to improve impact resistance, tensile strength, and flexural strength of a cured composite comprising the resin when cured, and

polymerizing the polymerizable coupling agent.

Depending on the type of fibre and the type of coupling agent it may be necessary to pretreat the surface of the fibre to enable it to be coated with the coupling agent. For example, where the fibres comprise mica platelets such platelets are usually coated with a metal oxide coating (e.g. iron oxide or other metal oxide) prior to coating with the polymerizable hydrophilic coupling agent.

According to another embodiment of this invention there is provided a process for making a plurality of reinforcing fibres, said process comprising:

mixing the plurality of fibres with a liquid comprising a polymerizable coupling agent for coupling said fibre to a resin so as to improve impact resistance, tensile and flexural strength of a cured composite comprising the resin when cured, and polymerizing the polymerizable coupling agent in the liquid so as to substantially coat the surfaces of the plurality of fibres with polymerized coupling agent.

Depending on the type of fibre and the type of coupling agent it may be necessary to pretreat the surface of the fibre to enable it to be coated with the coupling agent. For example, where the fibres comprise mica platelets such platelets are usually coated with a metal oxide coating (e.g. iron oxide or other metal oxide) prior to the mixing step.

The process may further comprise the step of separating the plurality of fibers from the liquid.

The process may further comprise the step of sieving the separated plurality of fibers.

According to a further embodiment of this invention there is provided a reinforcing fibre for a curable resin made by the process of the invention.

According to an additional embodiment of this invention there is provided a cured composite comprising:

a cured resin incorporating a plurality of reinforcing fibres each of said reinforcing fibres having a surface which is substantially coated with a coupling agent for coupling said fibre with the cured resin so as to improve impact resistance, tensile, and flexural strength of said cured composite, said coupling agent comprising a polymerized coupling agent

According to an additional embodiment of this invention there is provided a curable composite comprising:

a curable resin incorporating a plurality of reinforcing fibres each of said reinforcing fibres having a surface which is substantially coated with a coupling agent for coupling said fibre with the resin when cured so as to improve impact resistance flexural strength, and tensile strength of said composite when cured, said coupling agent comprising a polymerized coupling agent.

According to another embodiment of this invention there is provided a process for making a cured composite comprising:

preparing a curable composite by combining a curable resin and a plurality of reinforcing fibres each of said reinforcing fibres having a surface which is substantially coated with a coupling agent for coupling said fibre with the resin when cured so as to improve impact resistance, flexural and tensile strength of a cured composite comprising the cured resin, said coupling agent comprising a polymerized coupling agent, and curing said curable composite.

According to another embodiment of this invention there is provided a method of applying a composite to a surface said method comprising:

preparing a curable composite by combining a curable resin and a plurality of reinforcing fibres each of said reinforcing fibres having a surface which is substantially coated with a coupling agent for coupling said fibre with the cured resin so as to improve impact resistance, flexural strength and tensile strength of a cured composite comprising the cured resin, said coupling agent comprising a polymerized coupling agent;

applying the curable composite to the surface; and

curing said curable composite.

The step of applying can be by painting, pumping, brushing, wiping, streaking, pouring, rolling, spreading or other suitable applying methods used in fibreglass fabrication. By choosing fibres of mean length less than about 4 mm the resin having said plurality of reinforcing fibres can be applied to the surface by spraying.

A composite which is the subject of this invention can utilize fibres the maximum mean length of which is about 3-4 mm more typically about 3 mm (the composite which is the subject of this invention can be pumpable and/or sprayed using current fibreglass deposition equipment a requirement that restricts mean fibre length to a maximum 4 mm). A critical fibre length of the same order of magnitude was unacceptable for these particular applications. Thus for these applications it was of paramount importance to reduce the critical fibre length to under 1 mm. This is achieved by improving coupling and reducing interfacial stresses by plasticizing the interface by thoroughly coating the fibre with coupling agents such as silane coupling agents or suitable organo metal ligands, such as transition metal acrylates.

According to another embodiment of this invention there is provided a method of moulding a composite said method comprising:

preparing a curable composite by combining a curable resin and a plurality of reinforcing fibres each of said reinforcing fibres having a surface which is substantially coated with a coupling agent comprising a polymerized coupling agent for coupling said fibres with the cured resin so as to improve impact resistance, tensile strength, and flexural strength of the composite when cured;

locating the curable composite in a mould; and

curing said curable composite in the mould.

The step of locating the curable composite in the mould may comprise pumping it, pouring it or otherwise placing it, in the mould. Where the moulding process involves injection moulding the step of locating the curable composite in the mould comprises injecting the curable composite into the mould.

This invention teaches the use of resins including flexible resins and resins with moderately high elongation at break to overcome the poor impact resistance.

Throughout this specification it is to be understood that a unique aspect regarding coupling agents used to coat the fibres in this patent is that coupling agents are polymerized before and/or during the coupling process. It is of paramount importance to have a preponderance of polymers adhering to the surface as the presence of these polymers effectively stress relieve the interface during curing of the composites which can be short fibre composites. Two or more different coupling agents may be used.

Usually the fibres do not have sizing agents of any sort on the surface of the fibres. In order to obtain such fibres from standard fiberglass fibres which come coated with sizing agents it is necessary to remove such sizing agents from the fibres before coating the fibres with a coupling agent. In addition, the density of coupling agents on the surface of the fibres is extremely high—usually the polymerization of the coupling agent is performed to a substantial extent. For example, the step of polymerizing the coupling agent comprises polymerizing the coupling agent for a period in the range 5-60 hours, typically a period in the range 10-30 hours, 12-30 hours, 15-30 hours, 15-30 hours or 20-30 hours. Typically the step of polymerizing the coupling agent comprises polymerizing the coupling agent for a period such as 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 or 30 hours.

Thixatropes such as fumed silica/inorganic thixatropes interfere with the resin bonding to fibres, by adding to interfacial stresses. Organic thixatropes especially the amide type such as Thixatrol Plus and glyceryl stearate products help plasticize then interface and therefore improve bonding. These are preferred products when optimum strength of the composite is required.

Usually the entire external surface of a fiber is substantially coated with the coupling agent.

Examples of Materials

The following list is by way of exemplification only and is by no means an exhaustive list.

Monomers and Oligomers Mono and di and trifunctional acrylates and methacrylates, styrene, and polyallyl ethers.

GP UPE Laminating Resins

Eterset 2504 PT orthophthalic ethylene glycol fumaric acid resin, Eterset 2597 PT orthophthalic ethylene glycol fumaric acid resin, and NAN YAR LA111 orthophthalic ethylene glycol fumaric acid resin.

Chemical Resistant UPE Resins

Eterset 2733 Ortho NPG fumaric acid chemical resistant resin,

Eterset 2731 Iso NPG fumaric acid chemical resistant resin, NAN YAR GL316 Iso NPG fumaric acid chemical resistant resin, Swancor 901 45, Swancor 911 45, Hetron 922. and Derakane 411 45.

Flexible Resins

SYN6311 Cray Valley, F61404-30 NUPLEX, Swancor 980 Toughened VE

Swancor 981 Flexible VE, and Aromatic Corp flexible VE.

Cure In Air UPE Resins

ROSKYDAL 500A, and VUP4732 SOLUTIA.

Toughening Additives

SARTOMER CN962 URETHANE ACRYLATES, SARTOMER CN964 URETHANE ACRYLATES, SARTOMER CN965 URETHANE ACRYLATES and HYCAR REACTIVE LIQUID POLYMER 1300X33 VTBNX.

Plasticizers

PALAMOL ADIPATES, and DI BUTYL PHTHALATE.

Cure In Air Additives

SANTOLINK XI 100, PMMA, and PS

Thixatropes

Rheox THIXIN E, Rheox THIXATROL+, FUMED SILICAS Cabot, Wacker, and TREATED CLAYS.

Promoters

COBALT OCTOATE, COBALT OXALATE, POTASSIUM OCTOATE, ZIRCONIUM OCTOATE, VANADIUM NAPHTHENATE, COPPER NAPHTHENATE, ZINC OCTOATE, and DMA.

Inhibitors

ACETYL ACETONE, HYDROQUINONE, and TBHQ.

Air Release Agents

BYK A515 AND 510. SWANCOR 1317, BEVALOID 6420 and EFKA20.

Leveling Agent

EFKA 777

Catalysts

MEKP, CHP, and benzoyl peroxide

Fibres

Milled glass fibres made from (Vetrotex, Camalyef, SUR100,HPR800), Kevlar/aramid fibres, Wollastonite fibres, Nylon fibres, and calcined surface treated micas

Fillers

Zenospheres, PVC Powder, and treated organo clays.

Coupling Agents

Silanes/acrylic functional, silanes/vinyl functional, silanes/styrene functional, silanes and zinc diacrylate.

The advantages of this Technology over the current art are:

    • Fewer people required to produce a part—no laminators required.
    • Improved work place health and safety, fewer people exposed to styrene emission, lower styrene levels.
    • Much faster mold turnaround, increased productivity.
    • Improved chemical resistance.
    • Composite can be applied by robot.

The invention provides amongst other things a sprayable/pumpable reinforced resin composite that does not require mechanical consolidation. This composite can be used for fabricating FRP objects such as swimming pools, boats, baths, spas, liquid storage tanks, fibreglass panels, cowlings, etc. It can be used with foaming resins to add mechanical strength, and it is ideally suited to resin injection molding.

BEST MODE AND OTHER MODES FOR CARYING OUT THE INVENTION

Modification of the Surface of Fibres and Methods of Forming Composites

The standard surface treatment of fibres is not satisfactory. The silane coupling agents used are not applied thoroughly in the case of glass rovings. Commercially available milled glass rovings are manufactured from continuous rovings which have been coated with a sizing material such as EVA or PVA emulsion. This sizing must be removed from the milled glass prior to coating the fibre with coupling agent. And in the case of mineral fibres the coupling agents on commercially available fibres are too low in molecular weight and density on surface of the fibres.

In order to optimize the performance of the composites it is necessary to optimize the application of silanes to modify the chemistry and therefore the forces at the interface of the fibres with the resin. This may be achieved by partially polymerizing the silane coupling agents prior to bonding them to the fibres.

In one form this may be achieved by allowing the silanes in aqueous solution to polymerize at suitable pH (pH 7 or greater) for a suitable time, prior to acidification and coupling.

It is theorized that the reaction rate of the higher molecular weight silanes bonding to the fibres is considerably slower due to, among other influences, steric hindrance. For this reason fibres are left soaking in the aqueous silane for up to a day or longer to optimize the population of higher molecular weight silanes on the surface.

The aim is to improve bonding, and stress relieve the interface during polymerization of the resin matrix.

Reducing interfacial stress is critical to optimize the performance of the short fibre composite.

Alternatively (where the fibres are not coated with acid soluble materials such as iron oxides), the coupling agent may be mixed with the fibres at acidified pH (e.g. about pH 3) and the pH gradually raised over 10-36 hours to pH 7+/−1 pH unit. Where the fibres are not coated with acid soluble materials such as iron oxides, the coupling agent may be mixed with the fibres at neutral pH (e.g. about pH 7) and the pH maintained or gradually raised over 10-36 hours to pH 9+/−1 pH unit.

Throughout this specification the terms fibre and fibres are to be taken to include platelet and platelets respectively. Surface treated mineral fibres such as Wollastonite, and ceramic fibres such as glass fibres are the most suitable fibres for this invention however surface treated synthetic fibres can be used (e.g. surface treated aramid fibres, mylar fibres, nylon fibres, linear polyethylenes, linear polypropylenes, polyesters and carbon fibres). Maximum fibre length 6 mm, mean fibre length 4 mm or less. Alternatively, surface treated platelets such mica platelets (if precoated with a suitable metal oxide such as iron (III) oxide, iron (II) oxide, titanium dioxide, tungsten oxide, hafnium dioxide, nickel oxide, cobalt oxide, manganese dioxide, chromium trioxide, vanadium pentoxide, zinc oxide, molybdenum trioxide, tin dioxide, indium trioxide, niobium pentoxide, tantalum pentoxide, zirconium dioxide etc).

Resins with an elongation to break of greater than 6% are preferred. The most suitable resins are those which are naturally tough and with an elongation at break greater than 10%.

For lining of concrete vessels, and steel vessels to improve their chemical resistance, resins with low elongation at break are suitable.

However for load bearing structures the resins with higher elongation at break give best performance.

As mentioned before the more “elastic” the resin is the stronger and more serviceable the composite.

As the % of reinforcement increases so do the mechanical properties of the composite up to a point, and then the tensile strength of the laminate begins to fall.

Until better bonding is achieved between the resin and the reinforcement, fibre contents of around 30% to 50% by weight appear optimum.

The most suitable resins are epoxy vinyl ester resins, tough vinyl functional urethane resins, tough vinyl functional acrylic resins, and flexible polyester resins—the non plasticized type.

% by Weight
Formulation Space (a) for Method 1
Resin20% to 89.999%
Reactive monomers and or oligomers0% to 30%
Fibres coated with or oxide coated platelets10% to 60%
coated with Coupling Agents Silanes,
and or Organo-Metal Compounds
Promotors/Catalysts0.001% to 10% active
ingredient
Thixatropic Agents0% to 30%
Pigments0% to 35%
UV Stabilizers0% to 20%
Formulation Space (b) for Method 1
Reactive Diluents (Vinyl functional monomers20% to 89.999%
and oligomers)
Non Reactive Diluents0% to 30%
Fibres coated with or oxide coated platelets10% to 60%
coated with Coupling Agents Silanes,
and or Organo-Metal Compounds
Promotors/Catalysts0.001% to 10% active
ingredient
Thixatropic Agents0% to 30%
Pigments0% to 35%
UV Stabilizers0% to 20%
Formulation Space (c) for Method 1
Resin + Reactive Diluents (Vinyl functional20% to 89.999%
monomers + oligomers)
Non Reactive Diluents0% to 30%
Fibres coated with or oxide coated platelets10% to 60%
coated with Coupling Agents Silanes,
and or Organo-Metal Compounds
Promotors/Catalysts0.001% to 10% active
ingredient
Thixatropic Agents0% to 30%
Pigments0% to 35%
UV Stabilizers0% to 20%

These formulations can be sprayed using conventional fibreglass depositors. For Example Glasscraft, Venus Gussemer, Binks Sames, etc.

One typical process for coating glass and/or wollastinite fibres comprises:

Coupling solution: to water add 0.1-1 wt % silane coupling agent, adjust pH to pH 3 typically using acetic acid or equivalent, add 50 parts by weight of uncoated glass fibres and/or wollastinite fibres, agitate slowly just to suspend fibres, slowly raising the pH over 24 hours to pH 7, then filter fibres, then dry to >0.1 wt % at about 110° C. Sieve dried, coated fibres through 800 μm+/−200 μm screen. Avoid agglomeration of fibres prior to adding to resin. Incorporate fibres into resin gradually to optimise wetting of individual fibres and so as to avoid clumping in the resin. Add promoter and initiator and optionally air release agent(s) and thixotrope(s) and allow a composite to form. The resultant composite, when cured, has improved impact resistance, tensile and flexural strenght as compared to fibre composites where the fibres have not been treated as described above.

Another typical process for coating glass and/or wollastinite fibres comprises:

Coupling solution: to water add 0.1-1 wt % silane coupling agent, adjust (if necessary) pH to pH 7+/−1 pH unit to allow partial polymerisation of coupling agent and then adjust to pH 3 typically using acetic acid or equivalent, add 50 parts by weight of uncoated glass fibres and/or wollastinite fibres, agitate slowly just to suspend fibres, slowly raisng pH over 24 hours to pH 7, then filter fibres, then dry to >0.1 wt % at about 110° C. Sieve dried, coated fibres through 800 μm+/−200 μm screen. Avoid agglomeration of fibres prior to adding to resin. Incorporate fibres into resin gradually to optimise wetting of individual fibres and so as to avoid clumping in the resin. Add promoter and initiator and optionally air release agent(s) and thixotrope(s) and allow a composite to form. The resultant composite has improved impact resistance, flexural strength, and tensile strength as compared to fibre composites where the fibres have not been treated as described above.

A further process for coating glass and/or wollastonite fibres comprises:

Coupling solution: to water add 0.1-1 wt % silane coupling agent, adjust (if necessary) pH to pH 7+/−1 pH unit to start polymerisation of coupling agent, add 50 parts by weight of uncoated glass fibres and/or wollastonite fibres, agitate slowly just to suspend fibres stir slowly for about 24 hours, then filter fibres, and dry to >0.1 wt % at about 110° C. Sieve dried, coated fibres through 800 μm+/−200 μm screen. Avoid agglomeration of fibres prior to adding to resin. Incorporate fibres into resin gradually to optimise wetting of individual fibres and so as to avoid clumping in the resin. Add promoter and initiator and optionally air release agent(s) and thixotrope(s) and allow a composite to form. The resultant composite has improved impact resistance, flexural and tensile strength as compared to fibre composites where the fibres have not been treated as described above.

One typical process for coating mica platelets (5 microns to 4000 microns) comprises:

Precipitate iron hydroxide from an iron (III) containing solution (eg 0.01-1M ferric chloride) by adjusting the pH to about > pH 9 onto mica platelets. Filter platelets an dry at 400° C. Coupling solution: to water add 0.1-1 wt % silane coupling agent, adjust pH to pH 7, add 50 parts by weight of Fe2O3 coated mica platelets, agitate slowly just to suspend platelets. Slowly agitate platelets in solution for 24 hrs, then filter platelets, then dry to >0.1 wt % at about 110° C. Sieve dried, coated platelets through suitable aperture screen to break up agglomerates. Avoid agglomeration of platelets prior to adding to resin. Incorporate platelets into resin gradually to optimize wetting of individual platelets and so as to avoid clumping in the resin. Add promoter and initiator and optionally air release agent(s) and thixotrope(s) and allow a composite to form. The resultant composite has improved impact resistance, tensile strength, and flexural strength as compared to platelet composites where the platelets have not been treated as described above.

Another typical process for coating mica platelets comprises:

Precipitate iron hydroxide from an iron (III) containing solution (eg 0.01-1M ferric chloride) by adjusting the pH to about > pH 9 onto mica platelets. Filter platelets and dry at 400-600° C. Allow to cool then mill to mean particle size in the range 3 mm-1 μm and then sieve. Coupling solution: to water add 0.1-1 wt % silane coupling agent, adjust (if necessary) pH to pH 7+/−1 pH unit to allow partial polymerisation of coupling agent add 50 parts by weight of calcined mica platelets, agitate slowly just to suspend platelets, slowly for 24 hours, then filter platelets, then dry to >0.1 wt % moisture at about 110° C. Sieve dried, coated platelets through suitable screen to break up agglomerates. Avoid agglomeration of platelets prior to adding to resin. Incorporate platelets into resin gradually to optimise wetting of individual platelets and so as to avoid clumping in the resin. Add promoter and initiator and optionally air release agent(s) and thixotrope(s) and allow a composite to form. The resultant composite has improved impact resistance, tensile strength, and flexural strength as compared to composites where the platelets have not been treated as described above.

A further process for coating process for coating mica platelets comprises:

Precipitate iron hydroxide from an (III) containing solution (eg 0.01-1M ferric chloride) by adjusting the pH to about > pH 9 onto mica platelets. Filter platelets and dry at 400° C.-600° C. Coupling solution: to water add 0.1-1 wt % silane coupling agent, adjust pH to pH 7 to start polymerisation of coupling agent, add 50 parts by weight of calcined mica platelets, agitate slowly just to suspend platelets stir slowly for about 48 hours, then filter platelets, and dry to >0.1 wt % at about 110° C. Sieve dried, coated platelets through 800 μm+/−200 μm screen. Avoid agglomeration of platelets prior to adding to resin. Incorporate platelets into resin gradually to optimise wetting of individual platelets and so as to avoid clumping in the resin. Add promoter and initiator and optionally air release agent(s) and thixotrope(s) and allow a composite to form. The resultant composite has improved impact resistance, tensile strength, and flexural strength as compared to composites where the platelets have not been treated as described above.

Fibre Length Specification

Fibre length maximum 6 mm, typically less than 2 mm. Fibre length distribution in the range 6 mm to 1 μm.

Fibre Length Disitribution SpaceWt %
>=4 mm0% to 20%
<4 mm, >=2 mm0% to 35%
<2 mm, >=1 mm0% to 50%
<1 mm0% to 100%

A typical fibre length space for swimming pools or liquid storage tanks

>=4 mmLess than 2% by Wt fibres
<4 mm but >=2 mmBetween 5% and 50% by Wt fibres
<2 mmBetween 5% and 50% by Wt fibres
Typical Tensile Strength of Method60 to 100 MPa
1 laminates
Typical Flexural Strength80 to 150 Mpa

Method 2 Applying a laminate that contains chopped rovings but does not require mechanical consolidation.

Method 2 relies on a resin being non air inhibited. This can be achieved in two ways. By incorporating a suitable thermoplastic polymer at approximately 0.3% to 1% by weight of total vinyl functional constituents. Or by adding suitable allyl crosslinkers that stop air inhibition. These are added at concentrations between 4% and 35% of total vinyl functional constituents.

Method 2 allows for fibres to be sprayed onto the mould with the non air inhibited resin as chopped rovings in the normal way. However it is best if the resin contains approximately 15% by volume short fibre liquid composite described in method 1, this is because the short fibre composite has good mechanical properties.

Much less chopped rovings are required to achieve adequate strength when combined with the short fibre composite.

This allows for “resin to glass” ratios greater than 3 to 1. The excess resin available is used to hose down “furries” that is chopped rovings protruding from the wet laminate.

This laminate does not require mechanical consolidation and is potentially stronger than the Method 1 Laminate.

Deposition is as follows

1. Spray a bed with the liquid composite about 0.1 mm to 0.3 mm deep.

2. Then spray liquid composite and chopped rovings together thinly leaving about 5% to 10% of the first layer visible

3. Spray the “dry” rovings with liquid composite until completely wetted.

4. Spray rovings and liquid composite as in 2.0 then spray “dry” rovings as in 3.

5. Repeat step 4. until the required thickness is achieved.

6. Allow to cure and demold if necessary.

Please note that this procedure does not require laminating.

If the laminate needs to be chemically resistant then step one above can he repeated until 1.5 two 2.5 mm of liquid composite is deposited prior to building up the laminate.

In Method 2. the resin in the liquid composite can be a standard laminating resin as the average composite fibre length is much greater than 4 mm.

Typical Tensile Strength of Method 2 laminates>100 MPa
Typical Flexural Strength>150 MPa

Composite/Laminate Thickness

Any thickness of composite can be achieved simply by applying multiple passes. It is best to use a build between 0.5 mm and 1.0 mm per pass, this minimizes air entrapment.

EXAMPLES

Laboratory test laminates have been sprayed using a Binks Sames pressure pot Binks hand-piece internal catalyst mix. Robinson catalyst system. Operating pressure 80 psi—air nebulized.

Mold waxed melamine board.

Small spa mould.

Test sample mold

A small two person spa was made using a Robinson depositor and the resin formulated below.

The coping was reinforced with the Method 2 laminate. The product was successfully demolded. It was able to hold a full volume of water unsupported.

Sprayed and test molded panels have been tested to required ASTM test methods for Tensile Strenght, Tensile Modulus, Flexural Strength, and Flexural Modulus.

Typical results for Method 1 laminates are

Flexural Strength 80 MPa to 160 MPa

Flexural Modulus 5 Gpa to 6 Gpa

Tensile Strength 60 Mpa to 110 Mpa

Tensile Modulus 5 GPa to 6 GPa.

Typical composite
Swancor 981 flexible Vinyl Ester resin 100 parts
Styrene  10 parts
Thixatrol + amide thixatrope  3 parts
Cobalt octoate 6% solution 0.5 parts
Di methyl analine0.15 parts
Treated wollastonite fibres  38 parts
Air release agent Swancor 1317 0.7 parts

Summary of test results
Type 2 Composite
The weight % for test samples are as follows
10% silane/acrylic surface treated wallstonite or milled glass fibres for composites
made using a combination of chopped fibreglass rovings and liquid composite. Resin
composite to chopped rovings ratio (equivalent to resin to glass ratio) 3.5:1 Resins used:
Impact tests
1. Swancor 980 toughened VE resin25 kg/cm2 Charpy ASTM D256
2. Swancor 981 flexible VE resin22 kg/cm2 Charpy ASTM D256
3. F61404/30 Nuplex Flexible UPE resin19 kg/cm2 Charpy ASTM D256
4. 2504 Eterset GP laminating resin8 kg/cm2 Charpy ASTM D256
Tensile test ASTM D638M
1. Swancor 980 toughened VE resin158 MPa
2. 2. Swancor 981 flexible VE resin134 MPa
3. F6140/30 Nuplex Flexible UPE resin65 MPa
4. 2504 Eterset GP laminating resin109 MPa
Test Results for Method 1 Composites
Liquid Composite 35% W.V. Silane treated fibres
Impact Tests
1. Swancor 980 toughened VE resin22 kg/cm2 Charpy ASTM D256
2. Swancor 981 flexible VE resin21 kg/cm2 Charpy ASTM D256
3. F61404/30 Nuplex Flexible UPE resin??kgcm/cm2 Charpy ASTM D256
4. 2504 Eterset GP laminating resin5 gcm/cm2 Charpy ASTM D256
Tensile Strength Tests ASTM D638M
25% W.V. Silane acrylic coated fibres
LA111 NanYar GP laminating resin60 MPa
Swancor 98188 MPa
F61404 Nuplex flexible UPE45 MPa (Necking resin too elastic)
Swancor 98093 MPa
Flexural Strength ASTM D790M
40% Silane styrene functional coated fibres
Swancor 980152 MPa
G16404/30??MPa (Indeterminate too flexible)

Dated Nov. 7, 2001