United States Patent 3772136

An air pervious, water repellent, self-supporting fibrous mat is produced by spraying a mixture of polyamide polymer and a suitable, rapidly evaporating compatible solvent. The fibrous mats are suitable for use as fabrics, decorative applications, tamper-proof bottle sealers, packaging materials, etc.

Application Number:
Publication Date:
Filing Date:
Primary Class:
Other Classes:
156/62.2, 156/251, 264/205, 450/93, 521/78, 521/98, 521/184, 521/185, 602/45
International Classes:
C08G69/34; C08G69/36; D04H1/56; (IPC1-7): B32B5/02; D04H1/00
Field of Search:
View Patent Images:
US Patent References:
3550806METALLIC STRUCTURES1970-12-29Peerman et al.
3501368INTERLINING1970-03-17Schabert et al.
3449273HOT MELT ADHESIVE1969-06-10Kettenring et al.
3280140Process for manufacturing polyamide resin1966-10-18Sharkey
3256304Polymeric fat acids and process for making them1966-06-14Fischer et al.
3016599Microfiber and staple fiber batt1962-01-16Perry
2927906Solution of polyamides in trifluoroethyl alcohol and process of making same1960-03-08Schlack

Primary Examiner:
Lesmes, George F.
Assistant Examiner:
Thibodeau, Paul J.
Parent Case Data:

This application is a continuation-in-part of my earlier filed application Ser. No. 741,433, filed July 1, 1968 and now abandoned.
Now, therefore, I claim

1. An air pervious and water repellent polyamide fibrous mat comprised of fibers which are essentially non-uniform in thickness and length and which have along their length a number of non-uniform totally enclosed air pockets, said fibrous mat having been prepared by spraying a solution of a polyamide dissolved in a solvent having an evaporation rate of 5.5 or less onto a support at a gage pressure in excess of 3 lb., said polyamide being selected from the group consisting of (1) copolymers of self-condensed aminolactams or aminoacids or mixtures thereof and the condensation products of dicarboxylic acids and diamines and (2) polymers of the condensation products of polymeric fat acids and diamines and said fibrous mat being further characterized as being self-supporting when released from a support backing therefor.

2. The fibrous mat of claim 1 wherein the polymeric fat acid is polymerized tall oil fatty acid.

3. The fibrous mat of claim 2 wherein the polymeric fat acid has a dimer acid content of at least 80 percent by weight.

4. The fibrous mat of claim 1 wherein the diamine has the formula of H2 N-R'-NH2 wherein R' is an aliphatic, cycloaliphatic or aromatic hydrocarbon radical of 2-40 carbon atoms.

5. The fibrous mat of claim 1 wherein the polyamide is selected from the group consisting of

6. The fibrous mat of claim 1 wherein the polyamide solution contains at least five percent by weight of dissolved polyamide.

7. The fibrous mat of claim 6 wherein the solvent is a chlorinated hydrocarbon solvent.

8. The fibrous mat of claim 7 wherein the solvent is methylene chloride.

9. The fibrous mat of claim 7 wherein the solvent is chloroform.

10. The fibrous mat of claim 7 wherein the solvent is methyl chloroform.

11. The fibrous mat of claim 6 wherein the solvent is a mixture of solvents.

12. The fibrous mat of claim 11 wherein the solvent is a mixture of tetrahydrofuran containing up to 0.3 parts by weight of methanol per part of tetrahydrofuran.

13. A process of forming a bonded article which comprises simultaneously shearing at least two layers of the fibrous mat of claim 1 while the layers are in contact.

This invention relates to fibrous products prepared from polyamides. More specifically, this invention relates to self-supporting fibrous mats which are prepared by spraying a mixture of polyamide polymer and a fast evaporating compatible solvent.

It has been known that decorative web-like effects can be obtained by spraying veiling lacquers with a spray gun. In the past, these effects were obtained by spraying a formulated colored nitrocellulose to a previously painted base coat of contrasting color. Similar effects have been obtained with the use of synthetic rubbers and polyvinylidene chloride. However, these earlier sprayed effects were not self-supporting nor did they appear to be water repellent and air pervious. Likewise, they did not offer the advantages of the polyamides. These earlier applications were used almost exclusively as veiling lacquers sprayed over a substrate to produce decorative effects.

Turning to the drawings, it can be seen that FIGS. 1-5 are photomicrographs of portions of a self-supporting fibrous mat prepared in accordance with this invention.

FIG. 6 shows the fibrous mat bonded to a substrate.

FIG. 7 shows a raincoat made from the fibrous mat.

FIGS. 8 and 9 show a beverage can having the fibrous mat as a sanitary covering.

FIGS. 10 and 11 show a bottle having a tamper-proof seal of sprayed polyamide fibrous mat.

FIGS. 12-15 show the packaging of an object using two layers of the fibrous mat.

It has now been found that thermoplastic polyamides when dissolved in an appropriate solvent can be sprayed onto a substrate to produce a web-like effect. This web-like effect will hereinafter be referred to as a fibrous mat since the sprayed mat can be removed for a release type substrate and be self-supporting. The fibrous mat is comprised of fibers essentially non-uniform in thickness (or diameter) and length, alternating between areas having a solid cross-section with areas whose cross-section is tubular. The fibers thus have along their length a number of non-uniform totally enclosed gas pockets (i.e., bubbles). Various of the fibers are interconnected (or bonded) to each other to form air holes in the mat.

As used herein, the term "polyamide polymer" is intended to include thermoplastic polyamide resins made by the condensation polymerization of lactams and/or amino acids along with dicarboxylic acids and diamines including conventional dicarboxylic acids such as adipic acid, sebacic acid, etc. as well as the polymerized fatty acids. Polyamide polymers as used herein is also intended to include the thermoplastic polyamide resins prepared by the condensation polymerization of diamines and polymerized fat acids or polymerized fat acids in combination with conventional dicarboxylic acids.

When practicing this invention, one of the preferred embodiments includes the dissolution of a polyamide, which is the reaction product of a polymerized fatty acid and diamine as defined herein, in an appropriate, rapid evaporating solvent such as chloroform, methylene chloride, etc. This mixture is then sprayed under pressure, preferably at least 3 lb. gage pressure, from a conventional spray gun. Generally, the resin concentration in the solvent will be about 5 to 25 percent, preferably 15 to 20 percent by weight of resin. However, the resin content will vary with the type of spray equipment, solvent, application, and solubility of the polyamide in the solvent. When the above mixture is sprayed, as indicated, onto a substrate or a release type support such as tetrafluoroethylene fluorocarbon resin Teflon coated glass cloth, a fibrous mat can be formed. This mat will be air pervious and water repellent. It will be evident to those skilled in the art that optimum spraying conditions, i.e., pressure, nozzle selection, mat thickness, etc. will be readily apparent through a few optimum spray testing patterns.

A number of uses for the sprayed polyamide fibrous mat are illustrated in the drawings. The photomicrograph, FIG. 1, is approximately a 12X enlargement of a portion of the self-supporting fibrous mat as prepared in Example I. It can be seen that the mat has fibers, 1, and a number of small openings, 2, which will allow for the passage of air. Since the fibers are hydrophobic, the mat is water repellent.

FIGS. 2-5 are further photomicrographs of portions of the fibrous mat as prepared in Example I (enlargements of 150X, 250X, 250X and 1,000X, respectively). It can be seen that the mats have fibers, 1, openings, 2, bubbles within the fibers, 3, interconnected fibers, 4, and air holes, 5, formed by the interconnection of the fibers. In the photomicrographs of FIGS. 2-5, 1 mm. equals 6.6, 4, 4, and 1 micron, respectively. Thus the large bubble, 3, of FIG. 4 has a longest dimension of 286 microns, the diameter of the smallest fiber, 1, of FIG. 5 is 1 micron and the diameter of the smallest bubble, 3, of FIG. 5 is also 1 micron.

FIG. 6 shows the sprayed fibrous mat, 6, bonded to a substrate, 7.

FIG. 7 is a drawing of a raincoat prepared from cotton cloth, 8, onto which was sprayed the fibrous mat, 9, prior to cutting and sewing of the raincoat.

FIG. 8 shows a beverage can, 10, which has the fibrous mat, 11, sprayed over the top of the can to give a sanitary covering. In FIG. 9, the fibrous mat, 11, is partially peeled from the top of the can.

FIG. 10 shows a bottle, 12, which has been made tamper-proof by having the cap and bottle neck sprayed with the fibrous mat, 13. FIG. 11 shows the cap removed from the bottle and the tamper-proof seal broken, leaving jagged fibers, 14, wherever the seal has been broken.

FIG. 12 shows an object, 15, placed between two layers of the fibrous mat, 16. FIG. 13 shows the shearing by means of a scissors, 17, of both layers of the fibrous mat enclosing the object. FIG. 14 shows the object, 15, totally enclosed by the sheared fibrous mat layers, 16, which are joined by the shearing action along their outer edges. FIG. 15 is an end view along line 18-18 of the packaged object showing that the fibrous layers have a bond, 19, due to the shearing action.

As indicated above a variety of polyamide polymers are useful in the present invention. These include the condensation products of lactams and/or amino acids along with dicarboxylic acids and diamines. Various of these products are readily commercially available. They are normally defined by the weight percent content of the condensates of their individual starting materials. Thus the Elvamid resin used in Example XII is prepared by the condensation polymerization of caprolactam, hexamethylene diamine, adipic acid and sebacic acid with the resulting composition being defined as follows:

% by weight nylon 6, (polycondensate of 46 caprolactam) nylon 6,6 (condensation of 27 hexamethylene diamine and adipic acid) nylon 6,10 (condensation of 27 hexamethylene diamine and sebacic acid)

Likewise when 11-aminoundecanoic acid is used as a component, it is identified as nylon 11 (i.e., the condensate of 11-aminoundecanoic acid). These polyamides are prepared using known techniques which include the use of heat to amide forming temperatures--i.e., above about 100° to 300° C., such as 200°-250°C.

Suitable dicarboxylic acids have the general formula HOOC-R-COOH where R is an aliphatic or cycloaliphatic radical having 3-48 carbon atoms. Simple dibasic acids include glutaric, pimelic, adipic, sebacic, suberic, azelaic acid, etc. Diamines suitable in preparing the polyamides useful in the present invention are also illustrated hereinbelow following the description of the polymeric fat acid based polyamides and the polymeric fat acid reactants.

Other suitable polyamides are the reaction products of diamines and polymerized fatty acids or polymerized fatty acids in combination with simple dibasic acids. The polymeric fat acids which may be employed in preparing the polyamides are those resulting from the polymerization of drying or semidrying oils or the free fat acids or simple alcohol esters of these fat acids. The term "fat acids" is intended to include saturated, ethylenically unsaturated and acetylenically unsaturated, naturally occurring, and any synthetic monobasic aliphatic acids containing from 16 to 24 carbon atoms. The term "polymeric fat acid" refers to polymerized fat acids. The term "polymeric fat radical" refers to the hydrocarbon radical of a polymerized fat acid, and is generic to the divalent, trivalent, and other polyvalent hydrocarbon radicals of dimerized fat acids, trimerized fat acids and higher polymers of fat acids. The divalent and trivalent hydrocarbon radicals are referred to herein as "dimeric fat radical" and "trimeric fat radical" respectively.

The saturated, ethylenically unsaturated, and acetylenically unsaturated fat acids are generally polymerized by somewhat different techniques, but because of the functional similarity of the polymerization product, they are generally referred to as "polymeric fat acids."

Saturated fat acids are difficult to polymerize but polymerization can be obtained at elevated temperatures with a peroxidic catalyst such as ditertiarybutyl peroxide. Because of the generally low yields of polymeric products, these materials are not current commercially significant. Suitable saturated fat acids include branched and straight acids such as caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, palmitic acid, isopalmitic acid, stearic acid, arachidic acid, behenic acid, and lignoceric acid.

The ethylenically unsaturated acids are much more readily polymerized. Suitable polymerization methods are disclosed in U. S. Pat. Nos. 3,256,304 and 3,157,681. The ethylenically unsaturated acids can be polymerized using both catalytic or non-catalytic polymerization techniques.

The preferred aliphatic acids are the mono- and polyolefinically unsaturated 18 carbon atom acids. Representative of such acids are 4-octadecenoic, 5-octadecenoic, 6-octadecenoic (petroselinic), 7-octadecenoic, 8-octadecenoic, cis-9-octadecenoic (oleic), trans-9-octadecenoic (elaidic), 11-octadecenoic (vaccenic), 12-octadecenoic and the like. Representative octadecadienoic acids are 9,12-octadecadienoic (linoleic), 9,11-octadecadienoic, 10,12-octadecadienoic, 12,15-octadecadienoic and the like. Representative octadecatrienoic acids are 9,12,15-octadecatrienoic (linolenic), 6,9,12-octadecatrienoic, 9,11,13-octadecatrienoic (eleostearic), 10,12,14-octadecatrienoic (pseudo-eleostearic) and the like. A representative 18 carbon atom acid having more than three double bonds is moroctic acid which is indicated to be 4,8,12,15-octadecatetraienoic acid. Representative of the less preferred (not as readily available commercially) acids are: 7-hexadecenoic, 9-hexadecenoic (palmitoleic), 9-eicosenoic (gadoleic), 11-eicosenoic, 6,10,14-hexadecatrienoic (hiragonic), 4,8,12,16-eicosatetraenoic, 4,8,12,15,18-eicosapentanoic (timnodonic), 13-docosenoic (erucic), 11-docosenoic (cetoleic), and the like.

The polymerization of the described ethylenically unsaturated acids yields relatively complex products which usually contain a predominant portion of dimerized acids, a smaller quantity of trimerized and higher polymeric acids and some residual monomers. The dimerized acids, generally containing 32 to 44 carbon atoms can be obtained in reasonably high purity from the polymerization products by vacuum distillation at low pressures, solvent extraction, or other known separation procedures. It is preferred to have a dimer acid content of at least 80 percent, more preferably 90 percent. The polymerization product varies somewhat depending on the starting fat acid or mixture thereof and the polymerization technique employed--i.e., thermal, catalytic, particular catalyst, conditions of pressure, temperature, etc. Likewise, the nature of the dimerized acids separated from the polymerization product also depends somewhat on these factors although such acids are functionally similar.

As a practical matter, the dimeric fat acids are preferably prepared by the polymerization of mixtures of acids (or the simple aliphatic alcohol esters--i.e., methyl esters) derived from the naturally occurring drying and semi-drying oils or similar materials. Suitable drying or semi-drying oils include soybean, linseed, tung, perilla, oiticia, cottonseed, corn, sunflower, dehydrated caster oil and the like. Also, the most readily available acid is linoleic or mixtures of the same with oleic, linolenic and the like. Thus, it is preferred to use as the starting materials, mixtures which are rich in linoleic acid. An especially preferred material is the mixture of acids obtained from tall oil which mixture is composed of approximately 40-45 percent linoleic and 50-55 percent oleic.

Reference has been made hereinabove to the monomeric, dimeric and trimeric fat acids present in the polymeric fat acids. The amounts of monomeric fat acids, often referred to as monomer, dimeric fat acids, often referred to as dimer, and trimeric or higher polymeric fat acids, often referred to as trimer, present in polymeric fat acids may be determined analytically by gas-liquid chromatography of the corresponding methyl esters. Unless otherwise indicated herein, this analytical method was used in the analysis of the polymeric fat acids employed in this invention. Another method of determination is a micromolecular distillation analytical method. This method is that of R. F. Paschke et. al., J. Am. Oil Chem. Soc., XXXI (No. 1), 5, (1954), wherein the distillation is carried out under high vacuum (below 5 microns) and the monomeric fraction is calculated from the weight of product distilling at 155° C., the dimeric fraction calculated from that distilling between 155° and 250° C., and the trimeric (or higher) fraction is calculated based on the residue. When the gas-liquid chromatography technique is employed, a portion intermediate between monomeric fat acids and dimeric fat acids is seen, and is termed herein merely as "intermediate", since the exact nature thereof is not fully known. For this reason, the dimeric fat acid value determined by this method is slightly lower than the value determined by the micromolecular distillation method. Generally, the monomeric fat acid content determined by the micromolecular distillation method will be somewhat higher than that of the chromatography method. Because of the difference of the two methods, there will be some variation in the values of the contents of various fat acid fractions. Unfortunately, there is no known simple direct mathematical relationship correlating the value of one technique with the other.

The polymeric fat acid based polyamides useful in the present invention are prepared by conventional amidification procedures, usually heating the reactants to a temperature between 100° and 300° C., preferably 225°-250° C. for a time sufficient to complete the reaction, generally 2-8 hours. Essentially molar equivalent amounts of carboxyl and amine groups are employed in preparing the polyamide. As set forth above, the resins may also include copolymerizing diacids and the diamine component employed may be a single diamine or a mixture of two or more different diamine reactants. In addition, small amounts of monomeric, monocarboxylic acids may be present. With regard to any of the acid components, any of the equivalent amide-forming deriatives thereof may be employed, such as the alkyl and aryl esters, preferably alkyl esters having from 1-8 carbon atoms, the anhydrides or the chlorides.

The diamines which may be employed may be ideally represented by the formula

H2 N - R' - NH2

where R' is an aliphatic, cycloaliphatic or aromatic hydrocarbon radical preferably having from two to 40 carbon atoms. Likewise, R' may contain both aliphatic and aromatic hydrocarbon groupings. Illustrative polyamines are ethylenediamine, hexamethylenediamine, tetramethylenediamine, and the like, bis (aminoethyl)benzene, cyclohexyl bis(methyl) amine), dimeric fat diamine, etc. And as indicated previously the diamine may be employed alone or in mixtures of two or more. The most preferred diamines are the alkylene diamines having two- six carbon atoms in the alkylene group and mixtures thereof with dimeric fat amines.

The dimeric fat diamine, sometimes referred to as "dimer diamine", "dimeric fat amine" or "polymeric fat acid diamine" are the diamines prepared by amination of dimeric fat acids. A suitable method of preparation is disclosed in U. S. Pat. No. 3,010,782.

The copolymerizing compounds commonly employed are aliphatic, cycloaliphatic or aromatic dicarboxylic acids or esters defined by the formulae:

R1 OOC - COOR1 and R1 OOC-R"-COOR1

where R" is an aliphatic, cycloaliphatic or aromatic hydrocarbon radical preferably having from one to 20 carbon atoms and R1 is hydrogen or an alkyl group, preferably having one to eight carbon atoms. Such acids include oxalic, malonic, adipic, sebacic, suberic and the like.

When copolymerizing dicarboxylic acids are employed with the polymerized fat acids, it is preferred that the carboxyl groups from the polymeric fat acid should account for at least 50 equivalent percent of the total carboxyl groups. Likewise, in those polyamides as previously described prepared from an aminoacid and/or a lactam with a dibasic acid and a diamine wherein dimeric fat acid is included, it is preferred that the carboxyl groups from the dimeric fat acid should account for at least 50 equivalent percent of the total carboxyl groups.

As indicated previously, the polyamide is dissolved in a solvent which is capable of rapidly evaporating and sprayed from the solution to form a fibrous mat of the appearance shown in FIGS. 1 through 6. The solvents useful in this invention are those which dissolve the polyamide resin and have an evaporation rate of less than 5.5, preferably less than 3.0. The term "evaporation rate" as used herein is defined as the ratio of time required for a given volume of the solvent to evaporate at 73.5±2° F. and 50±4 percent relative humidity when compared to the same volume of diethyl ether which is assigned the value of one. A suitable testing procedure is given in the Paint Industry Magazine, Vol. 76, No. 4, p. 15, April 1961. To determined whether or not a solvent would dissolve the polyamide, the mixture of solvent and polyamide was placed in a conventional paint shaker for 1 hour of shaking. If at the end of that time, the resulting mixture was not clear, the system was determined to be incompatible. It has been found that chlorinated hydrocarbon solvents with a suitable evaporation rate work most satisfactorily. Solvents can generally be classified into three categories; very useful solvents having an evaporation rate of less than 3.0, operable solvents having an evaporation rate of about 5.5-3.0, and unsuitable solvents having an evaporation rate of above 5.5. Illustrative of evaporation rates of some representative solvents are listed as follows:

Group Solvent Evaporation Rate Control Diethylether 1.0 I Methylene chloride 1.8 Tetrahydrofuran 2.0 Chlororform 2.2 Methyl chloroform (1,1,1,-trichloroethane) 2.7 II Methanol 5.2 III Ethanol 7.0 n-propanol 7.8

Various mixtures of solvents can be used so long as they fall within the suitable evaporation rate. For instance, small amounts of solvents which by themselves would be within Groups II or III can be mixed with larger amounts of Group I and still have an evaporation rate of less than 5.5. It is therefore possible to have binary solvent systmes. Suitable mixtures include tetrahydrofuran with small amounts of methanol, and fluoronated hydrocarbons (Freon) and other commercial propellants with small amounts of alcohols which induce solubility and have the desired evaporation rate.

When spraying the polyamide resins from the solvent mixtures as described above, it has been found that the viscosity can significantly influence the type of web effect obtained. Generally, the viscosity of the resin is a function of the molecular weight and is the determinant of solution viscosity and product performance. The following shows the relation of the spray solution viscosity ranges:

Low viscosity--0.5-10.0 centipoises

Medium viscosity--10.0-65.0 centipoises

High viscosity--65.0-100.0 centipoises

Generally, a low viscosity, e.g., 0.5-10.0 cp., produces a finely divided fibrous spray which is solvent saturated when airborne in the spray. Since a large percentage of the atomized solvent is carried to and deposited on the substrate, the short resin fibers are partially redissolved giving a mat surface of unusual continuity. Generally, it is necessary to obtain an optimum balance between solids content of the solution, discharge rate and solvent evaporation rate. It is also known that as the viscosity increases, the solvent solution containing the resin becomes more difficult to discharge and atomize and the resulting fibrous texture of the mat eventually resembles a spattering of individual globules. Likewise, the bulk density of the mat increases with an increase in solution viscosity. Also, as is shown in the examples, the higher viscosity resins result in greater tensile strength and better elongation.

In order to use the fibrous mats as a decorative substance, it is desirable to be able to obtain various colors. It has been found that various colorants may be included in the solvent-resin mixture prior to spraying. Generally, hydrocarbon dyes are preferred over pigments. Suitable dyes include the Solvent series of dyes as listed in the "Colour Index," Society of Dyers and Colourists, 2nd Ed., 1956. Among the useful dyes are those having azo groups, xanthene groups, anthraquinone and triarylmethane groups. Illustrative are the following: Solvent Red 26, C.I. 26, 120: Solvent Green 3, C.I. 61, 565: Solvent Orange 7, C.I. 12, 140 wherein C.I. is the color index.

Various methods of spray application have been found to work satisfactorily. These include air gun spraying, aerosol spraying, air brush, and other conventional methods of spray application. The optimum spraying conditions can be easily obtained by simple spray testing techniques. An important element for an aerosol application is proper selection of the valve assembly. A useful nozzle is a Model 103 Newman-Green spray head having a 0.055 inch slot and a 0.060 inch orifice and a vapor tap hole in the capillary dip tube enlarged to 0.050 inch. Other methods of application will be readily apparent to those skilled in the art.

The spraying is preferably accomplished using solution temperatures of about 50° to 100° F., and even more preferably ambient room temperatures--i.e., about 70°-80° F. Also as indicated previously the spraying is carried out employing at least 3 lb. gage pressure. The spraying pressure varies as to the type of equipment, solution viscosity, etc. and the upper range may be quite high--i.e., 100 lb. gage pressure and higher. A preferred range is 35 to 45 lb. gage pressure. At any rate a sufficient pressure is needed for the sprayed composition to reach the receiving surface. Likewise, the distance of the latter from the spray orifice can vary widely. Thus, such surface is sufficiently far away from the orifice to allow the formation of the fibrous pattern or mat. Solvent evaporation is also facilitated by increased distance. Preferably, the receiving substrate will be from about 1 to 3.5 feet from the spray orifice with a distance of 14 to 30 inches being especially preferred.

As mentioned previously, the polyamide fibrous mat may be self-supporting or sprayed onto a support which will form part of the final article. When a self-supporting mat is desired, it must be formed on a material of the type that would release the mat. Such supports include Teflon, polished plate glass, metals, wire screens, or smooth surfaces containing conventional release coatings. Likewise, the polyamide may be sprayed onto various other substrates including paper, wood, metal, cotton, plastic film, synthetic fibers, etc.

A slight modification of the invention may be practiced by thermally treating the fibrous mat. If the polyamide is heated to a temperature slightly less than that at which the mat continuity is changed, the tensile strength and percent elongation are improved. Generally, this temperature is different for each polymer but common laboratory testing techniques will be readily apparent to those skilled in the art. As shown in Example X, a suitable thermal treating temperature for the resin of Example X is approximately 85° C. It is also possible for the fibrous mat to serve as an adhesive by heating the fibers to near or above the melting point of the polymer. Various colored sections of the mat may thus be attached to each other giving a checkerboard, decorative effect.

The sprayed polyamide fibrous mat of this invention may be useful as a textile material. For example, it has been found that the fibrous mat may be sprayed onto a cloth substrate. FIG. 7 shows a raincoat prepared from such material. Other uses include a coating for bottle caps to give a tamper-proof seal, paneling, decorative panels, creative art media, spary molded fabrics, wall covering, lampshades, decorative packages and papers, surgical dressings, protective covering for cans, water proofing agent, etc. The fibrous mat may also be used to produce a cover for the tops of wine bottles thus eliminating the need of a more expensive metal cover. Additionally, the fibrous mats have insulative and accoustical properties.

The fibrous mats of the invention also have the unique property of forming a bond when two or more layers thereof are simultaneously severed using a shearing action such as when cut employing a common scissors. This property is illustrated by FIGS. 12-15 wherein an object is packaged by placing same between two layers of the fibrous mat and simultaneously severing the two layers on all sides of the object. The bond strength is usually less than the strength of the fibrous mat facilitating clean separation when desired at the point or length of the said bond. Where the shearing apparatus is heated above ambient room temperature such that the point of contact thereof with the fibrous mat layers during the shearing is above about 150° F., the strength of the newly formed bond between the two layers is increased. Decorative effects can be achieved by utilizing different colored layers of the fibrous mat with the simultaneous shearing being in a pattern, predetermined or otherwise.

This invention is further illustrated by the following Examples which are not to be considered as limiting.


A polyamide was prepared from polymeric fat acids (polymerized tall oil fatty acids) and hexamethylenediamine by charging 111.5 lbs. of the polymeric fat acid into a flask along with 32.51 lbs. of hexamethylenediamine. The polymeric fat acid had the following properties:

Monomer--0.9 percent

Intermediate--4.6 percent

Dimer--93.4 percent

Trimer--1.0 percent

Acid Value--193

Saponification Value--196

Iodine Value--9.1

In addition to the above reactants, it is also possible to add an antifoaming agent as well as a color remover such as a 10 percent solution of phosphoric acid. In this example, 100 grams of the acid and 10 grams of a commerically available antifoaming agent were added to the reactants. The above reactants were heated to 250° C. over a period of 2 hours and the temperature was held at about 250° C. for 3.25 hours. The resulting polyamide had the following analysis:

Acid Value (meq./kg.)--7.6

Amine Value (meq./kg.)--35.8

Tensile Strength, psi--3,529

Yield Strength, psi--1,151

Percent Elongation--571

Melt Index at 175° C.--19.66 gm.

The melt index was determined according to ASTM D-1238-65T. A 10 gram sample of the above polyamide resin was then mixed with 90 grams of chloroform. The mixture was shaken in a paint mixer until a resulting clear solution was obtained, approximately 30 minutes.

The mixed solution was then charged to a type CM501 DeVilbiss spray gun. The spray gun pressure was set at 50 lb.+ gaged pressure and the mixture (at ambient temperature) was sprayed onto a Teflon coated glass cloth approximately 20 inches from the spray orifice. The evaporation rate of the solvent resulted in the polymer being deposited on the cloth as a stringy, tacky solid. The tackiness formed a continuity which renders a dry tissue-like film. The film is in the form of a fibrous mat which can be readily separated from the cloth and serves as a self-supporting fibrous mat. The fibrous mat had a density approximately 75 percent of that of a solid extruded film of the same polyamide.


A polyamide polymer was prepared as follows with a polymeric fat acid having the following analysis:

Monomer--1.6 percent

Intermediate--1.9 percent

Dimer--95.6 percent

Trimer--1.0 percent

Acid Value--191

Saponification Value--195

Iodine Value--8.9

The fat acid, in an amount of 125.0 pounds, was reacted with 52.5 pounds of 4,4'-diamino-3,3'-dimethyl(dicyclohexyl)methane.

The above reactants were heated to 250° C. for 3 hours and the temperature was maintained at 250° C. for 1 hour. A vacuum of 3 mm Hg was then applied and the temperature held at 250° C. for 5 hours under vacuum.

The resulting polyamide resin had the following analysis:

Acid Value--13.3

Amine Value--44.4

Tensile Strength, psi--4,998

Yield Strength, psi--4,219

Percent Elongation--205

Inherent Viscosity--0.583

The inherent viscosity is the natural logarithm of the relative viscosity divided by grams of the polyamide, generally 0.50 gm per 100 ml. of solvent, chlorophenol.

The spray procedure of Example I was repeated and similar results were obtained.


A polyamide was prepared as follows using a polymeric fat acid having the following analysis:

Monomer--0.6 percent

Intermediate--4.3 percent

Dimer--92.5 percent

Trimer--2.6 percent

Acid Value--194

Saponification Value--196

Iodine Value--10.1

The fat acid, in an amount of 30 pounds, was reacted with the following:

Azelaic acid--1.308 lbs.

Hexamethylenediamine--6.027 lbs.

Ethylenediamine--1.483 lbs.

The above reactants were heated to 250° C. for 3 hours and the temperature was maintained at 250° C. for 1 hour. A vacuum of 3 mm Hg was then applied and the temperature held at 250° for 5 hours under vacuum.

The resulting polyamide resin had the following analysis:

Acid Value--1.3

Amine Value--2.1

Tensile Strength, psi--2,102

Yield Strength, psi--719

Percent Elongation--595

Brookfield viscosity at 225° C.--317 poise

(No. 5 spindle at 4 rpm)

The spray procedure of Example I was repeated and similar results were obtained.


Example I was repeated except that the solvent used for the spraying application was methylene chloride. Results similar to those of Example I were obtained.


The following solution, Solution A, was prepared:

Polyamide from Ex. I--170 gms.

Dichloromethane--600 gms.

Tetrahydrofuran--220 gms.

Methanol--10 gms.

Gardner Viscosity at 25° C.--32 cps

The ingredients to prepare Solution A were placed in a paint shaker for 1 hour. Due to heat and pressure generated from the shaking, it was necessary to cool the mixing container and contents to room temperature before opening.

After cooling the above mixture, three 98.0 gram samples were withdrawn and placed into four 6 oz. glass jars. A separate 2 gm. 10 percent dye solution was placed into each glass jar and the respective dyes and Solution A were mixed on the paint shaker for 15 minutes. The three dyes were as follows:

Solvent Red 26, Color Index 26120

Solvent Green 3, Color Index 61565

Solvent Orange 7, Color Index 12140

Each of the three mixtures were sprayed at 40 lb. gage pressure with the spray gun as in Ex. I, onto a separate piece of Kraft wrapping paper. A decorative, artistic, colored, fibrous mat was obtained which remained adhered to the paper.


A tamper-proof container was prepared by first preparing the following spray solution:

Polyamide Resin of Ex. I--15 gms.

Dichloromethane--25 gms.

Tetrahydrofuran--60 gms.

Methanol--1 gm.

Gardner Viscosity--32 cps

The above ingredients were shaken in a paint shaker until a clear solution resulted, the solution was sprayed around the cap of a one-ounce bottle. The solution was sprayed with a Model H, Paasche Airbrush at 25-40 psig. A tamper-proof seal was obtained similar to that shown in FIG. 10. The seal can be easily broken but cannot be resealed by melting, heating or by other means without a complete re-spraying.


The following spray solution was prepared:

Polyamide Resin of Ex. I--17 gms.

Dichloromethane--60 gms.

Tetrahydrofuran--22 gms.

Methanol--1 gm.

Gardner Viscosity--32 cps

The spray solution was prepared in in Ex. VI and sprayed with an air gun as in Example I. The spray solution was applied to the top of a beverage can to form a sanitary covering as shown in FIG. 8. The covering was easily removed without the use of a release agent.

The same formula was used to spray a paper except that TiO2 in an amount of 10 percent of the weight of the total solution was added for a white base. A decorative paper was thus obtained.

The spray solution of this Example was applied directly to a molded lampshade to give a fibrous mat effect to the lampshade.

The spray solution was also applied to a brassiere form in which the cups were formed from filament-spray, fibrous mat. The straps and fastenings were of conventional construction.


A piece of highly sized cotton material of the type commercially available in a yard goods store was sprayed with the polyamide solution of Example VII. The spray solution was applied with an air gun as in Example I. Coverage of the spray was such that 114 grams of the dryed sprayed solution covered 2 square yards of the fabric. The sprayed cotton fabric was then cut and made into a raincoat as shown in FIG. 7. The raincoat was water repellent.


The following Example will illustrate the relative tensile strengths and percent elongation of the fibrous mat for various viscosity polymers. The polyamide resin used was that of Example I except that the viscosity for the three samples was varied as indicated below. The spray solution was prepared as indicated in the Table below. Each solution was prepared by weighing 100 gram samples into a 6 ounce glass jar, tightly sealed, and then placed in a paint shaker for 1 hour. The solutions were then sprayed onto Teflon coated glass cloth with the spray gun as used in Example I. The pressure was set at 35 psig and the spray gun was held approximately 20 inches from the substrate and a spraying stroke of about 18 inches used to apply the solution. All of the sample was sprayed onto the substrate. The mat was removed from the substrate and cut into strips 1 inch × 3 inch. The cut strips were then weighed amd the mat weight determined in gram/sq. in. To determine the tensile strength, the strips were placed between the jaws of an Instron Tester, Model TM, Instron Eng. Corp., Canton, Mass. The strips were placed so as to have exactly 1 inch of mat between the jaws, i.e., a jaw gap of 1 inch. The tester was set at a crosshead speed of 0.5 inch/min. The tensile strength is defined as the maximum load in grams for failure of the mat per mat weight in grams/area, i.e., gm/in2. Therefore, the tensile strength will have the units gms/gm/in2. The elongation becomes a direct reading of the distance of travel. The results are summarized in Tables I and II below. The mat weights marked with an asterisk indicates that 50 gram samples were sprayed rather than 100 gram samples.


Resin A B C Resin Viscosity (Brookfield 250 p 180 p No. 5 spindle, 4 rpm, 205°C.) Melt INdex at 175°F. 19.66 gm. Resin Amt. (gms.) 15 15 10 Dichloromethane (gms.) 60 60 60 Methanol (gms.) 1 1 1 Tetrahydrofuran (gms.) 24 24 29 Gardner Viscosity, of the solvent mixture -- 25°C., cps 22 14.4 14.4


Mat Wt. Tensile Strength Resin gm/in2 gm/gm/in2 % Elongation A 0.06* 1258 16.0 B 0.06* 1647 20.0 C 0.05* 2356 33.0 A 0.16 2220 40.0 B 0.16 2025 35.0 C 0.13 3179 90.0

example x

resin B of Example IX was tested to determine the effect of thermally treating the sprayed fibrous mat. The sprayed fibrous mat comprised of Resin B in Example IX was cut into 1 inch × 3 inche pieces and each piece weighed. The samples were then subjected to thermal treating by heating the samples to 50° C., 75° C., 80° C., and 85° C. respectively for 1 hour at the various temperatures. The effect on the tensile strength and percent elongation is summarized in Table III. It was found that the fibrous mat was generally destroyed at 90° C. or above.


Sample Sample Tensile Strength Elongation °C. Wt. gms gm/gm/in2 % Control 0.2060 1100 27 50°C. 0.2035 1073 19 75°C. 0.2045 1214 16 80°C 0.2030 1379 26 85° 0.2055 1281 35

it can been seen that generally heat treatment increases the tensile strength.


The following spray solution was prepared for aerosol application:

Polyamide Resin, Ex. I--18.0 gms.

Dichloromethane--40.0 gms.

Tetrahydrofuran--27.0 gms.

Methanol--15.0 gms.

Gardner Viscosity of the

solvent mixture at 25° C.--32.1 cps

This solution was prepared by charging the materials into a 6 ounce glass jar and placed in a paint shaker for 1 hour. A 60 gram sample of the solution was weighed into a standard 10 ounce tinplate aerosol container. The container was sealed with a Newman-Green valve having the following description: Model R-70-118, with a 0.030 inch capillary tubing, Epon (B 5.0) and a 0.060 inch vapor tap hole, 70 Durometer Buna gasket and a stainless steel spring. The container was injection filled with 40 grams of dichlorodifluoromethane (Freon-12) which pressurized the container to 40 psig. The spray head was a Model 103 Newman-Green sprayhead having a 0.055 inch slot and a 0.060 inch orifice. The solution was sprayed onto a paper substrate and a fibrous mat was formed on the substrate.


The following nylon copolymer spray solution was prepared:

Nylon copolymer resin*--10 gms.

Dichloromethane--45 gms.

Tetrahydrofuran--10 gms.

Methanol--40 gms.

Gardner Viscosity at 25° C.--32.1 cps

The nylon copolymer was a commercially available nylon resin having the following composition:

nylon 6 (polycondensate of caprolactam)--46 percent

nylon 6,6 (condensation of hexamethylenediamine and adipic acid)--27 percent

nylon 6,10 (condensation of hexamethylenediamine and sebacic acid)--27 percent

The spary solution was prepared in a paint shaker as in Example I and sprayed onto a tetrafluoroethylene coated glass cloth support. Results were similar to those of Example I.


Example XII was repeated except that the following solution was prepared:

Nylon copolymer resin--12.5 gms.

Dichloromethane--40.0 gms.

Tetrahydrofuran--10.0 gms.

Methanol--37.5 gms.

Gardner Viscosity at 25° C.--85 cps

The nylon copolymer resin of this example was

nylon 6-- 50 percent

nylon 6,6--20 percent

nylon 6,10--20 percent

nylon 11 (made from

11-aminoundecanoic acid)--10 percent

Results similar to Example XII were obtained.


Self-supported fibrous mats as prepared in Example I were tested for the formation of bonds by laying two 1 inch by 3 inch strips face to face and then severing the same by cutting across the width of one end of the two layers (approximately 1 inch from the end) using a scissors, either at ambient temperature (77° F.) or at 160° F. (the scissors were heated by soft soldering a 1/4 inch by 4 inch, 100 watt cartridge heater to each blade using a powerstat regulated to produce a line voltage of 25-28 volts). The cutting produced in each instance two bonded strips having lengths of approximately 2 and 4 inches (half of the length being contributed by each layer). The bond strength was measured using an Instron Tensile instrument at a crosshead speed of 0.5 inches/min. and a gap space between the positioning jaws of 1 inch. The strength of the bond formed using the scissors at room temperature was 217 grams (load at failure). The 160° F. heated scissors bond had a strength of 353 grams (load at failure).

This invention offers a very economical self-supporting or supported fibrous mat which has multiple uses including textile materials, decorative uses, and any other number of applications which will be readily apparent to those skilled in the art. Since the mats are extremely drapable, they will be useful in many types of complex applications.