DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] Embodiments of the invention are described in detail with reference to the examples below. FIGS. 1(a), 1(b) and 1(c) show the first example of the inventive elastic product for use as a cushion 1, wherein FIG. 1(b) is a perspective view of the cushion 1, FIG. 1(a) is an A-A cross section of FIG. 1(b), and FIG. 1(c) shows an inlet of a bag.

[0039] Referring to the drawings, the cushion 1 comprises a large number of expanded particles 2 and a highly-stretchable bag 3 in which the particles 2 are packed. In a specific manner, the bag 3 comprises a relatively thin inner fabric 3a and a somewhat thick outer fabric 3b, which are combined by sewing. A fastener 4 is sewed on part of the bag 3 in such a manner that when the fastener 4 is opened, an inlet 5 made of the inner fabric 3a can be pulled out.

[0040] The expanded particles housed in the bag 3 are a foam product prepared by pre-expansion of polystyrene beads according to an expanded bead polystyrene (EPS) process. In this example, the particle diameter (the average diameter of the expanded particles) is about 0.4 to 0.9 mm.

[0041] The expanded bead polystyrene (also called styrofoam) is generally manufactured by a process including (a) a pre-expanding step in which raw beads about 0.3 to 2 mm in diameter are heated to be expanded by about 10 to 90 times; (b) a drying and aging step in which the pre-expanded beads are allowed to stand in an aging silo for six hours or more so that air is allowed to infiltrate into the cells and that the pre-expanded beads are allowed to be in a stable state; and (c) an expanding and molding step in which the aged pre-expanded beads are charged into a mold of a molding machine and expanded again and fused by steam at a temperature of 115° C. to 125° C. This example uses the pre-expanded particles, which are provided before the final expanding and molding step.

[0042] The raw beads may be made of polystyrene resin, polyethylene resin, polypropylene resin, or the like, and preferably made of a polystyrene resin impregnated with a hydrocarbon blowing agent or the like. Particularly preferred is a polystyrene resin in which the residual styrene monomer content is reduced to 500 ppm. Such a polystyrene resin can form a cushion without fear of sick house syndrome (air pollution in houses).

[0043] The surfaces of 100 parts by weight of the raw beads are coated with 0.5 to 1.5 parts by weight of the flow-promoting agent, which serves as a lubricant when the expanded particles are allowed to move. The flow-promoting agent is effective in inhibiting an odd sound, which would otherwise be caused by friction between the expanded particles.

[0044] Preferred examples of the flow-promoting agent include a salt of a fatty acid and a metal, fatty acid amine, sorbitan fatty acid ester, aluminum hydroxide, talc, calcium carbonate, and polyethylene wax. Examples of the fatty acid include stearic acid, ethylene bis stearic acid, lauric acid, and palmitic acid. Examples of the metal include magnesium, calcium, zinc, barium, and aluminum.

[0045] Particularly preferred examples of the flow-promoting agent include zinc stearate, calcium stearate and magnesium stearate. The content of the agent should be from 0.5 to 1.5 parts by weight, preferably from 0.6 to 1.2 parts by weight, based on 100 parts by weight of the raw beads. If the content of the flow-promoting agent is less than 0.5 parts by weight, the odd sound-inhibiting effect can be insufficient. An increase in the effect may not be expected at a content of more than 1.5 parts by weight.

[0046] Butane or pentane is preferably used as the blowing agent. Cyclohexane is preferably used as a blowing assistant. The contents of polystyrene, butane or pentane and cyclohexane are preferably but not limited to 90 to 97% by weight, 3.0 to 8.0% by weight and 0 to 2.0% by weight, respectively.

[0047] The raw beads with such a composition are heated at a temperature of about 80° C. to 100° C. using steam or the like so that they are expanded by the expansion of the blowing agent. In this example, the expansion ratio is set at about 10 to 80 times, and the expanded particles are substantially spherical and controlled to have diameters of about 0.4 to 0.9 mm.

[0048] In this example, the particles expanded by the expansion of the blowing agent are allowed to rise by hot air at a specific pressure and introduced into an aging silo. In such a process, the hot air allows the expanded particles to move up by about 11 m and then to come into the aging silo. Until the particles are introduced in the silo, therefore, the surface of the expanded particles are dried and dewatered, and the replacement of the blowing agent by air is accelerated inside the expanded particles. Such a process also allows particle size selection to some extent so that expanded particles substantially uniform in diameter can be collected.

[0049] The process of completing the cushion 1 as shown in the drawings include the steps of pulling the inlet 5 out of the opened fastener 4 and blowing the expanded particles 2 through the inlet 5 into the inside of the bag 3. In such a process, the bag 3 is hung in such a manner that the inlet 5 faces upward in the perpendicular direction, and a specific amount of the expanded particles are blown into the bag 3 using air pressure. After the blowing process is completed, the inlet 5 is closed along a machine sewing line 5a and pushed back into the bag 3, and then the fastener 4 is closed.

[0050] The inner and outer fabrics 3a and 3b each comprise a two-way tricot fabric. This two-way tricot fabric has a nylon or polyester warp knitted (tricot) structure in which polyurethane is inserted. This example uses a combination of about 75 to 85% by weight of nylon and about 15 to 25% by weight of polyurethane.

[0051] In this example, the two-way tricot fabric achieves sufficient stretching properties in the length and width directions, and the outer fabric 3b is selected to have a thickness of 0.5 mm to 0.6 mm.

[0052] A specific extension percentage is also selected. Specifically, two types of test specimens in a size of 16 cm×2.5 cm are cut from the fabric, and one side of each specimen is pulled under a specific tension with the opposite side fixed. Through such a test, a fabric with a certain extension percentage as shown below is selected. Under a tension of 1 kilogram-force, the extension percentage should preferably be about 260 to 295% in the warp direction and about 105 to 135% in the fill direction; Under a tension of 1.5 kilograms-force, the extension percentage should preferably be about 290 to 320% in the warp direction and about 120 to 150% in the fill direction; Under a tension of 2.25 kilograms-force, the extension percentage should preferably be about 320 to 350% in the warp direction and about 135 to 165% in the fill direction; Under a tension of 3 kilograms-force, the extension percentage should preferably be about 340 to 370% in the warp direction and about 150 to 180% in the fill direction. In the measurement of the extension percentage, the test specimen with a size of 16 cm in the warp direction is extended in the warp direction, and the test specimen with a size of 16 cm in the fill direction is extended in the fill direction.

[0053] The bag 3 with the above structure is substantially full of the fine pre-expanded particles. In such a structure, the pre-expanded particles have substantially the same volume as the bag in the natural state (non-expanded state). Thus, the bag 3 exhibits good elasticity in combination with good stretching properties of the two-way tricot fabric.

[0054] FIGS. 2(a), 2(b) and 2(c) show a stuffed toy 6 in the shape of an animal, which is the second example of the invention. FIG. 2(b) is a perspective view of the stuffed toy 6, FIG. 2(a) is a B-B cross section of FIG. 2(b), and FIG. 2(c) shows an inlet of a bag.

[0055] The second example has substantially the same principal structure as the first embodiment. In this example, a titanium film is formed on the whole surface of the outer fabric 3b by sputtering process. The titanium film has a thickness of about 300 to 500 Å in view of feel to skin.

[0056] The stuffed toy 6 has good heat release properties because the outer surface of the outer fabric 3b is covered with the titanium film. When a child hugs the stuffed toy 6 and sleeps, heat from the child does not accumulate on the inner expanded particles 2. Even if rough handling causes damage to part of the fabric, the double layer structure formed of the inner and outer fabrics 3a and 3b can prevent the expanded particles 2 from leaking out.

[0057] FIGS. 3(a), 3(b), 4, and 5 show the third example of the invention used as inner bags 22 and 23 of a pillow PL. FIG. 3(a) is a perspective view showing the whole of the pillow PL, FIG. 4 is a perspective view showing the inner structure of the pillow PL, and FIG. 5 is a C-C cross section of FIG. 3(a).

[0058] The inner bags 22 and 23 each have the same principal structure as the first example, wherein the structure comprises expanded particles with an average diameter of 0.1 to 1.0 mm and a two-way tricot fabric with a thickness of 0.3 to 1.5 mm that envelopes the particles. In this example, the inventive product is used as the inner bags of the pillow, in which the fine pre-expanded particles and the two-way tricot fabric with good stretching properties work together to provide good elasticity for each of the inner bags 22 and 23 similarly to the first example.

[0059] Referring to FIG. 4, the pillow PL comprises an outer bag 21 in the shape of a substantially rectangular parallelepiped and the cylinder-shaped inner bags 22 and 23 housed in the outer bag 21, wherein the bag 22 is smaller than the bag 23. The outer bag 21 comprises tent fabrics 24 to 27 each lacking in stretchability and stretchable fabrics 28A and 28B with good stretching properties, wherein the fabrics 24 to 27, 28A and 28B are sewn together. More specifically, the tent fabrics form the bottom 24 and four sides 25A and 25B of the outer bag 21, a transverse band 26 placed in the top face of the bag21, and a tie strip 27 connecting the transverse band 26 to the bottom 24; and the highly stretchable fabric forms the two top faces 28A and 28B, which are separated by the transverse band 26.

[0060] In the outer bag 21, the four sides include front and back long sides 25A and left and right short sides 25B. The front and back sides 25A are each substantially rectangular. As shown in FIG. 3(b), however, the left and right sides 25B are each in the shape of a wavy rectangle with its long sides wave-like curved.

[0061] The pillow PL has different heights. For example, the front and back sides 25A, which will be perpendicular to the height direction of the user, each have a substantially rectangular shape in a size of 60 cm (long side)×3 cm (short side), and the left and right sides 25B each have a wavy rectangular shape with a long side of about 40 cm and maximal heights of about 7 cm (H1) and about 5.5 cm (H2) in the short side direction. A fastener 29 is provided along the back side 25A and the left side 25B. The pillow PL is completed when the fastener 29 is closed.

[0062] The effective height of the tie strip 27 connecting the transverse band 26 to the bottom 24 is substantially equal to the height of the front or back side 25A, but each inner bag is a little higher than the front or back side. Thus, the transverse band 26 is restrained by the tie strip 27 so that the completed pillow PL is dented at the midsection to have a wavy shape (FIG. 3(a)).

[0063] The two stretchable fabrics 28A and 28B differ in width (the size in the height direction of the user). For example, the first fabric 28A has a size of about 12 cm×60 cm, and the second fabric 28B about 23.5 cm×60 cm.

[0064] In this example, the stretchable fabrics 28A and 28B are each two-way tricot similarly to the inner bag 22 or 23. Specifically, the stretchable fabrics 28A and 28B are each made of about 75 to 85% by weight of nylon and about 15 to 25% by weight of polyurethane. Similarly to the second example, a titanium film is formed on the outer surfaces of the stretchable fabrics 28A and 28B to meet the requirements for heat release.

[0065] Referring to FIG. 4, the two inner bags 22 and 23 each have a cylindrical shape and differ in diameter. The inner bag 22 with a relatively small diameter is formed in a size corresponding to the size of the first fabric 28A, and the inner bag 23 with a relatively large diameter is formed in a size corresponding to the size of the second fabric 28B. As indicated by the arrows in FIG. 4, the two bags 22 and 23 are inserted in small and large housing spaces, respectively, which are separated by the tie strip 27. The bags 22 and 23 are held in a somewhat compressed state.

[0066] The two inner bags 22 and 23 are each formed by a process including the steps of packing the pre-expanded particles into each bag and then closing an opening 22a or 23a by means of double fasteners adjacently provided inside and outside in a dual manner. The closing direction of the inner fastener is opposite to that of the outer fastener, and the outer fastener is covered with the fabric of the bag so as not to be seen from outside. In general, the user does not become aware of the existence of the fasteners. Even if the user becomes aware of the outer fastener, the user may often be unaware of the inner fastener. Such a structure can prevent mischievous children from removing the contents.

[0067] Next, a description is provided of the working state of the restful sleep pillow PL according to the example. Referring to FIG. 6, the user of the pillow PL puts her or his head on the second fabric 28B of the outer bag 21. The load is applied to the center of the inner bag 23 so that the inner pre-expanded particles could shift to extend the inner bag 23 in the left and right directions. At the same time, the inner pre-expanded particles could shift from the head side downward along the neck.

[0068] However, the four sides of the outer bag 21 each comprise the tent fabric lacking in stretchability. Thus, the force for shifting the pre-expanded particles in the left and right directions produces upward expansion of the inner bag 23. In addition, the force for shifting the pre-expanded particles downward produces small expansion of a portion behind the neck. In the pillow PL, therefore, the inner pre-expanded particles would shift so as to embrace the whole of the head, and therefore a sleeping posture with the head forming an S-shaped curve can be achieved (see FIG. 7(a)), which is similar to the human standing posture. If the user tosses in her or his sleep, the four sides of the outer bag 21, which are restrained by the tent fabric, allow the pre-expanded particles to drift in response to the tossing so that a comfortable sleep posture can be maintained. In contrast, FIG. 7(b) shows the working state of a conventional cotton pillow, in which the height or hardness of the pillow is not suitable for the user so that the sleep posture as shown can be a cause of shoulder stiffness or headache.

[0069] The pillow PL may be used in direct contact with the head or may be used via a pillow cover. The pillow cover is preferably made of a pile material. Herein, the pile material means a fabric whose surface has a dense feather texture, a towel fabric whose surface has fine loops, or the like, including velveteen, corduroy and velvet.

[0070] The effectiveness of the above-described pillow PL has been demonstrated by a test and evaluation result report by Consumer Product End-Use Research Institute Co., Ltd. The test was carried out as shown below.

[0071] Body Pressure Dispersion Test

[0072] The pillow PL according to the example and a conventional product were subjected to the test. A body pressure sensor was placed under each test product, on which the subject (user) put the head when the pressure was measured. The conventional product was a Tempur® pillow, which has been suggested to form a best balanced support for the human body by its deformation depending on the body temperature and pressure.

[0073] In the test environment at 18±2° C. and 55±5%RH, the pressure was measured with or without a pillow cover attached to each test product. The subject was a woman in her twenties, and the comparison between the tests was performed on the same person. The test results are shown in FIGS. 8(a), 8(b), 9(a), and 9(b). FIGS. 8(a) and 8(b) show the results of the test of the example without and with the pillow cover, and FIGS. 9(a) and 9(b) show the results of the test of the comparative example without and with the pillow cover.

[0074] Each drawing three-dimensionally shows the values measured by the pressure sensor. From the comparison between FIGS. 8(a) and 8(b) and FIGS. 9(a) and 9(b), it is apparent that a sharp pressure peak is found in the comparative example while such a sharp peak is not found in the example. Thus, it is demonstrated that smooth dispersion of the body pressure is achieved in the example.

[0075] Up to this point, the description is provided of the third example of the invention. The above specific description is not intended to limit the scope of the invention. For example, the fourth example of the invention including small and large inner bags 22 and 23 integrated with each other as shown in FIG. 10 may be provided as an alternative to the third example including the separate inner bags 22 and 23. Any appropriate method may be used to form such an integrated structure. For example, a single bag may be sewn at its midsection with a sewing machine to form two inner bag sections 22 and 23, or two separate inner bags 22 and 23 may be sewn to be integrated with each other. In any case, it is preferred that the pre-expanded particles are packed into each of the integrated inner bags.

[0076] When two separate inner bags are integrated as shown in FIG. 10, the boundary portion exists originally, and therefore the outer bag 21 does not need the tie strip 27 as shown in FIG. 4. In the fourth example as shown in FIG. 10, the outer bag 21 has no transverse band 26 in its top face, and the whole of the face consists of the two-way tricot fabric. Even in such a structure including small and large inner bags 22 and 23 integrated in the outer bag 21, the large inner bag 23 in contact with the cervical vertebra part of the user can maintain a comfortable posture.

[0077] FIG. 11(a) is a plan view showing an inner bag 22 according to the fifth example. The pre-expanded particles are housed in the inner bag 22 whose D-D cross section has the shape as shown in FIG. 11(c). Referring to the drawings, the inner bag 22 (including sections 22A and 22B) has a circular boundary portion 15, which is formed by sewing together the front and back fabrics of the inner bag 22. More specifically, the boundary portion 15 is slightly shifted from the center to one side in the height direction of the user, while it is formed at the center of the width of the pillow (in the left and right directions).

[0078] The boundary portion 15 shaped like a circle can be insufficiently effective in inhibiting shifts of the inner expanded particles in the height direction of the user, but can be useful in a pillow for children whose head is relatively light. For the purpose of improving the shift-inhibiting effect, another inner bag 30 may be inserted into the original inner bag 22 (see FIG. 11(b)).

[0079] FIG. 11(a′) is a plan view showing an inner bag 22 according to the sixth example. The pre-expanded particles are also housed in the inner bag 22 whose D-D cross section also has the shape as shown in FIG. 11(c).

[0080] In the sixth example, a rectangular boundary portion 16 is formed by sewing together the front and back fabrics of the inner bag 22. Such a rectangular boundary portion 16 can surely inhibit shifts of the inner expanded particles in the height direction of the user, and therefore can be useful in a restful sleep pillow for adults. The boundary portion 16 is formed so as to be perpendicular to the height direction of the user, and divides the inner bag 22 into two sections 22A and 22B different in length in the height direction of the user.

[0081] While preferred embodiments of the invention have been shown and described above, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention.