Reinforcement material for foam molded products, molded products, and method for manufacturing the molded products

Abstract

Provided are a reinforcing material for foamed molded articles that has excellent mold-following properties, particularly for molds with deep recesses and projections, and that can suppress the seepage of foaming components; a molded article; and a method for producing the molded article. [Solution] The reinforcing material for foamed molded articles of the present invention has a nonwoven fabric layer formed by entangling first staple fibers and second staple fibers, the first staple fibers are binder staple fibers, at least a portion of the surface of the second staple fibers has a water-repellent layer, and the blending ratio of the binder staple fibers to the second staple fibers is (20-80) / (80-20), and the reinforcing material for foamed molded articles can be molded into a predetermined three-dimensional shape by press molding. The molded article of the present invention can be obtained by press molding the reinforcing material.

Description

[Technical Field]

[0001] The present invention relates to a reinforcing material for a foam molded product that can be molded into a predetermined three-dimensional shape by press molding, a molded product obtained by press molding the reinforcing material, and a method for producing the molded product. [Background technology]

[0002] Foam molded articles such as urethane foam are used as cushioning materials for vehicle seats (seats) and the like. A reinforcing material may be disposed on the surface of such foam molded articles. For example, a reinforcing material including a nonwoven fabric layer is disposed on the cushioning material of vehicle seats in order to prevent a decrease in the rigidity of the cushioning material and to prevent friction noise caused by friction between the cushioning material and springs (Patent Documents 1 and 2).

[0003] When producing a foam molded article, a reinforcing material is press-molded to fit the shape of a mold for the foam molded article, and then the molded article is placed in the mold, and a foaming component is poured into it and foamed under heat and pressure to obtain the foam molded article. During the pouring or foaming of the foaming component, the foaming component may penetrate the reinforcing material and exude. When a foam molded article in this state is used as a cushioning material for a vehicle seat, there is a problem of friction noise being generated due to friction between the exuded foaming component and the spring.

[0004] As a reinforcing material that suppresses the seepage of foaming components during molding, Patent Document 3 discloses a urethane reinforcing material that is a nonwoven fabric made of a blend of crimped composite staple fibers and water-repellent staple fibers, in which the blend ratio of the water-repellent staple fibers to the crimped composite staple fibers is in the range of 3 / 97 to 40 / 60, and the basis weight, 50% elongation stress, and breaking elongation are within specific ranges. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Utility Model Registration No. 3207739 [Patent Document 2] International Publication No. 2015 / 034069 [Patent Document 3] Utility Model Registration No. 3150605 Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, the reinforcing material is press-molded to fit the shape of the mold for the foam molded product. Therefore, the reinforcing material needs to have high extensibility so that it can be molded into a desired three-dimensional shape during press molding. Furthermore, in recent years, foam molded products with uneven shapes have been in demand, and molds with deep unevenness are used to produce such foam molded products. In such molds with deep unevenness, if the reinforcing material does not sufficiently conform to the mold, it will not be possible to produce a uniform thickness, and the reinforcing material may become thin or break in parts, which may lead to seepage of the foaming component, or the reinforcing material and the foam molded product will not have the desired three-dimensional shape. Therefore, a reinforcing material that can be used in molds with deep unevenness and can suppress the foaming component is required.

[0007] Patent Document 3 does not mention molding a urethane reinforcing material into a predetermined three-dimensional shape by press molding. Furthermore, the urethane reinforcing material described in Patent Document 3 is specified to have a load at 50% elongation of 1.0 to 15.0 N / 5 cm. This characteristic indicates that the urethane reinforcing material stretches with a weak force. Taking these disclosures into consideration, it appears that the urethane reinforcing material described in Patent Document 3 is one in which it is placed in a mold and molded with urethane in a single step, without first being molded into a predetermined three-dimensional shape by press molding. However, this type of reinforcing material has poor conformability to mold irregularities, making it unsuitable for molds with deep irregularities, and thus posing the problem of insufficient suppression of bleeding in foamed molded articles with deep irregularities.

[0008] The present invention aims to provide a reinforcing material for foamed molded articles that has excellent mold conformability, particularly for molds with deep recesses and projections, and that can suppress the seepage of foaming components, as well as a molded article obtained by press-molding the reinforcing material and a method for producing the molded article. [Means for solving the problem]

[0009] The reinforcing material of the present invention (hereinafter referred to as "the reinforcing material") is a reinforcing material for foamed molded bodies that can be formed into a predetermined three-dimensional shape by press molding, and has a nonwoven fabric layer formed by entangling first staple fibers and second staple fibers, the first staple fibers being binder staple fibers, at least a portion of the surface of the second staple fibers having a water-repellent layer, and the blend ratio of the first staple fibers to the second staple fibers being (20-80) / (80-20).

[0010] The molded article of the present invention (hereinafter referred to as "the molded article") is a molded article obtained by press-molding the present reinforcing material. The method for producing the molded article of the present invention includes a step of heating the present reinforcing material and a step of press-molding the heated present reinforcing material. [Effects of the Invention]

[0011] The reinforcing material for a foamed molded product and the molded product of the present invention have excellent mold conformability, particularly to a mold with deep recesses and projections, and can suppress exudation of the foaming component when the foamed molded product is produced using such a mold. The method for producing a molded product of the present invention can provide a molded product with excellent mold conformability. DETAILED DESCRIPTION OF THE INVENTION

[0012] This reinforcing material has a nonwoven fabric layer formed by entangling first staple fibers and second staple fibers. The method for entangling the first staple fibers and second staple fibers is not particularly limited, and known nonwoven fabric manufacturing methods can be applied. The first staple fibers and second staple fibers can usually be entangled by a needle punching method.

[0013] The first short fibers are binder short fibers. When this reinforcing material is press-molded into a predetermined three-dimensional shape, at least a portion of the binder component in the short fibers melts due to heat, thereby partially bonding the fibers that make up the nonwoven fabric. This stabilizes the three-dimensional shape of the reinforcing material after press molding.

[0014] The binder staple fibers are not particularly limited in their composition, as long as they contain a binder component that can at least partially melt when heated and partially bond the fibers that make up the nonwoven fabric. The binder staple fibers are usually composed of two components: a high-melting component and a low-melting component that acts as a binder component. More specifically, examples of the binder staple fibers include staple fibers having a core-sheath structure that consists of a core that is a high-melting component and a sheath that is a low-melting component.

[0015] When the binder short fibers contain a high-melting component and a low-melting component, the blending ratio of the two is not particularly limited. The blending ratio (by weight) of the high-melting component and the low-melting component is usually (30 to 70) / (70 to 30). When the blending ratio is within the above range, the extensibility, particularly the extensibility at high temperatures, is high, and the fiber can more easily conform to a deep mold, which is preferable.

[0016] The "low melting point" of the low melting point component means a melting point lower than the temperature during press molding, or a melting point of 90°C to 150°C. The "high melting point" of the high melting point component means a melting point higher than the temperature during press molding, or a melting point of 200°C to 300°C.

[0017] The second staple fibers have a water-repellent layer on at least a portion of their surface. The method for forming the water-repellent layer is not particularly limited. Examples of such methods include entangling the first and second fibers and then performing a water-repellent treatment, or using water-repellent staple fibers as the second staple fibers and entangling them with the first staple fibers. The water-repellent staple fibers are fibers in which a water-repellent layer is formed on at least a portion of the fiber surface by performing a water-repellent treatment on the staple fibers. Examples of the water-repellent treatment include silicone treatment and fluorine treatment.

[0018] The material of the first and second staple fibers is not particularly limited. Examples of such materials include polyester, polyethylene, and polypropylene. Polyester is preferred as the material. The first and second staple fibers may be made of the same material or different materials. The high-melting point component and the low-melting point component may be made of the same material or different materials. Furthermore, when the binder staple fibers have a core-sheath structure, the core and sheath may be made of the same material or different materials. Specific examples of the binder staple fibers include staple fibers made of high-melting point polyester and low-melting point polyester, particularly staple fibers made of a core made of high-melting point polyester and a sheath made of low-melting point polyester.

[0019] The length of the first and second staple fibers is usually 75 mm or less. There is no particular limitation on the lower limit of the length, but it is usually 20 mm or more, preferably 30 mm or more. When the length is within this range, it is preferable that the entanglement of the first and second staple fibers is improved and the tensile strength of the nonwoven fabric layer is improved. In addition, the fiber diameter of the first and second staple fibers is usually 8 dtex or less, preferably 4 dtex or less. There is no particular limitation on the lower limit of the fiber diameter, but it is usually 3 dtex or more. The length and / or fiber diameter of the first and second staple fibers may be the same or different.

[0020] The blending ratio (by weight) of the first and second short fibers is (20-80) / (80-20), preferably (30-70) / (70-30), and more preferably (35-65) / (65-35). The upper and lower limits of the blending ratio can be any integer within the above range. An excess of the first short fibers is undesirable because the reinforcing material may adhere to the mold during press molding. An insufficient amount of the first short fibers is undesirable because the rigidity after press molding may be insufficient, resulting in an unstable three-dimensional shape of the foamed molded article.

[0021] The blending ratios of the first and second short fibers in the fiber raw material are not particularly limited and can be within an appropriate range. The blending ratios (by weight) of the first and second short fibers are usually, independently, 20 to 80%, preferably 30 to 70%, and more preferably 30 to 65%. The upper and lower limits of the blending ratios can be any integer values ​​within the above ranges.

[0022] Due to the above-mentioned configuration, the present reinforcing material has high extensibility, particularly at high temperatures, and is excellent in moldability upon heating and shape retention upon cooling. Specifically, the present reinforcing material preferably has a load at 75% elongation in a tensile test at high temperatures of 100 N / 5 cm or less, preferably 90 N / 5 cm or less. Furthermore, the present reinforcing material preferably has a difference between the load at 75% elongation and the tensile strength in a tensile test at high temperatures of 60 N / 5 cm or more, preferably 70 N / 5 cm or more, and more preferably 80 N / 5 cm or more. When the load at 75% elongation and the difference between the load at 75% elongation and the tensile strength are within the above-mentioned ranges, the reinforcing material has high extensibility at high temperatures and excellent conformability even in molds with deep recesses and grooves. As a result, exudation of the foaming component can be suppressed in foam-molded articles obtained in molds with deep recesses and grooves, which is preferable. The "load at 75% elongation and tensile strength in a tensile test at high temperatures" are values ​​measured using the tensile test method and conditions at 140°C described in the Examples section.

[0023] The load at 5% elongation of the reinforcing material is preferably 10 N / 5 cm or more, and more preferably 15 N / 5 cm or more. If the load at 5% elongation is within the above range, the reinforcing material can be automatically inserted into a mold by machine during press molding, which is preferable. The "load at 5% elongation" is a value measured using the tensile test method and conditions at 25°C described in the Examples section.

[0024] The load at 75% elongation and the difference between the load at 75% elongation and the tensile strength can be adjusted appropriately by adjusting the blending ratio of the binder short fibers in the raw fiber and the punch density and needle depth in entanglement by needle punching. For example, increasing the blending ratio of the binder short fibers in the raw fiber can reduce the load at 75% elongation and increase the difference between the load at 75% elongation and the tensile strength. In addition, increasing the punch density and needle depth in entanglement by needle punching can increase the tensile strength and increase the difference between the load at 75% elongation and the tensile strength.

[0025] The reinforcing material may contain one or more types of fibers other than the first staple fiber and the second staple fiber, as long as the effects of the present invention are not impaired. Examples of such other fibers include known antibacterial fibers, flame-retardant fibers, and moisture-absorbing and heat-generating fibers. The blending ratio (by weight) of such other fibers in the fiber raw material is usually 5 to 40%, preferably 10 to 30%. The upper and lower limits of the blending ratio can be any integer value within the above range.

[0026] The reinforcing material has a nonwoven fabric layer formed by entangling the first and second short fibers. The reinforcing material may be composed of only the nonwoven fabric layer, or may include other layers as long as they do not impair the effects of the present invention. There are no particular limitations on the basis weight, thickness, and breathability of the nonwoven fabric, and these can be set to appropriate values ​​as needed. The basis weight of the nonwoven fabric is usually 80 to 150 g / m 2 , preferably 100 to 140 g / m 2 The air permeability is usually 120 to 200 cm 3 / (cm 2 s), preferably 140 to 180 cm 3 / (cm 2 ·s). The upper and lower limits of the basis weight and breathability can be any integer value within the above-mentioned ranges. The thickness of the nonwoven fabric is usually 0.8 to 3 mm, preferably 1.5 to 2.5 mm. The lower limit of the thickness range can be 0.9 mm, 1 mm, 1.2 mm, 1.4 mm, or 1.6 mm. The upper limit of the thickness can be 2.9 mm, 2.8 mm, 2.7 mm, 2.6 mm, or 2.4 mm. The thickness range can be any combination of the above-mentioned values. The breathability is a value measured based on the JIS L1906 Frazier method.

[0027] The material and type of the foam molded product are not particularly limited. Examples of the material for the foam molded product include urethane. Specific examples of the foam molded product include cushioning materials, more specifically cushioning materials for vehicle seats. The foam molded product can usually be obtained by press-molding the reinforcing material to fit the shape of a mold for foam molded products to obtain a foam molded product, placing the molded product in the mold, pouring a foaming component into the mold, and then foaming the foam molded product.

[0028] The present molded body is obtained by press-molding the present reinforcing material. There are no particular limitations on the method and conditions of the press-molding, as long as the present reinforcing material can be molded. The press-molding is usually press-molding using a mold. The press-molding may be cold press-molding (press-molding in which the material is heated) or hot press-molding (press-molding in which the mold is heated). Specifically, the present molded body can be obtained, for example, by a method including a step of heating the present reinforcing material and a step of press-molding the heated present reinforcing material. [Example]

[0029] The present invention will be specifically described below with reference to examples. Note that the present invention is not limited to the embodiments shown in the examples. The embodiments of the present invention can be modified in various ways within the scope of the present invention depending on the purpose and application.

[0030] 1. Manufacturing of reinforcement materials The following fibers were used as raw materials: (1) Binder fiber A bicomponent polyester fiber (thickness: 4.0 dtex, length: 5.1 cm) containing 50% by mass of low-melting-point polyester (melting point: 110°C) as the low-melting-point component and 50% by mass of high-melting-point polyester (melting point: 260°C) as the high-melting-point component. (2) Water-repellent fibers High-melting polyester fiber (melting point: 260°C) treated with a fluorine-based oil to make it water-repellent (thickness: 2.0 dtex, length: 5.1 cm). (3) Other fibers High melting point polyester fiber (melting point: 260°C) (thickness: 2.0 dtex, length: 5.1 cm).

[0031] The raw fibers, consisting of (1) binder fibers, (2) water-repellent fibers, and (3) other fibers, were passed through a carding machine to prepare a web. The webs were cross-layered to prepare a laminated web. The laminated web was needle-punched to entangle the fibers, thereby preparing a needle-punched nonwoven fabric, a reinforcing material of the example. The blending ratios (by weight) of the (1) binder fibers, (2) water-repellent fibers, and (3) other fibers are shown in Table 1.

[0032] The reinforcing material of the comparative example was prepared in the same manner as in the example, except that (1) binder fiber and (3) other fiber were used as raw material fibers. The blending ratios (by weight) of the (1) binder fiber and (3) other fiber are shown in Table 1.

[0033] 2. Evaluation Method A. Thickness, basis weight, density The thickness and basis weight of each reinforcing material in the Examples and Comparative Examples were measured. Furthermore, the air permeability of each reinforcing material in the Examples and Comparative Examples was measured according to the JIS L1906 Frazier method. The results are shown in Table 1.

[0034] B. Tensile Test The mechanical properties of the reinforcing material were examined at 25° C. and 140° C. using a tensile testing machine (Shimadzu Corporation Autograph AGS-5kNX). The results are shown in Table 1.

[0035] Tensile tests at 25 ° C were performed according to the following procedure. Rectangular test pieces measuring 200 mm in length and 50 mm in width were cut from the reinforcing materials of the examples and comparative examples (see Figure 4 of JP 2023-106813 A). Two test pieces were prepared: one in which the flow direction of the manufacturing process (hereinafter referred to as the "MD direction") was the longitudinal direction (tensile direction), and the other in which the direction perpendicular to the MD direction (hereinafter referred to as the "CD direction") was the longitudinal direction. 20 mm wide chucks were attached to both ends of the test piece, and the test piece was set so that the gauge length was 100 mm. A tensile test was performed at a tensile speed of 100 mm / min, and the tensile strength (N / 50 mm) at 5%, 30%, 50%, 75%, and 100% elongation of the test piece, as well as the tensile strength (N / 50 mm) at break and the elongation at break (mm) were measured. Tensile tests were performed three times in the MD direction and three times in the CD direction, for a total of six times, and the arithmetic mean values ​​of these six measurements were used as the tensile strength (maximum load) and breaking elongation. The elongation percentage φ (%) was calculated as φ = {(L - L) / L × 100}, where L is the gauge length before the test (= 100 mm) and L is the gauge length after the break (breaking elongation).

[0036] The tensile test at 140°C was performed according to the following procedure (see Figure 5 of JP 2023-106813 A). Using the same method as the tensile test at 25°C, rectangular test pieces measuring 200 mm in length and 50 mm in width were cut from the reinforcing materials of the examples and comparative examples. Two hair irons with a pair of clamping sections and a clamping width of 25 mm were prepared. The two hair irons were placed adjacent to each other and fixed with a fixture to prevent them from separating from each other. The total width of the clamping sections was 50 mm. A cushion sheet was adhered to the inside of the clamping sections so that when the pair of clamping sections was closed, the pair of clamping sections did not come into contact and a gap of 3 mm to 5 mm was formed between the pair of clamping sections. The center of the test piece set in the tensile tester was clamped between the two hair irons heated to 140°C and maintained for 10 seconds. As mentioned above, since the total width of the clamping sections was 50 mm, the test piece was also heated over a width of 50 mm. In addition, there was a gap between the pair of clamping parts, so that each clamping part of the hair iron did not come into contact with the test piece. After 10 seconds, the test piece was still clamped by the hair iron, and a tensile test was performed using the same method and conditions as the tensile test at 25°C (except for the load at 5% elongation).

[0037] C. Water repellency test The test was carried out in accordance with "JIS L 1092 Spray Test." The number of tests was N=3 for each of the examples and comparative examples.

[0038] D. Urethane exudation evaluation The reinforcing materials of the Examples and Comparative Examples were press-molded to fit the shape of a mold for foam molding (a shape that fits the area near the headrest stay attachment point on the back side of a front seat of an automobile). The molded reinforcing materials were then placed in a mold for foam molding, and urethane, a foaming component, was poured into the mold. The foaming component was then foamed under heat and pressure to produce the foam moldings of the Examples and Comparative Examples, which are cushioning materials. The produced foam moldings (N=5) were visually inspected for the presence or absence of bleeding to the backside of the reinforcing material. The foam moldings were also placed on the back side of a front seat of an automobile, near the headrest stay attachment point, and a person's hand or body was pressed against the foam molding to check for creaking noises. These results are shown in Table 1.

[0039] [Table 1]

[0040] In Table 1, "-" indicates that the elongation rate of some test specimens was less than 100%, and therefore there were no measurement results for the "load at 100% elongation."

[0041] 3.Results As can be seen from Table 1, the reinforcing material of the example did not exhibit urethane impregnation on the back surface, and did not produce creaking noises when used with springs. In contrast, the reinforcing material of the comparative example exhibited urethane impregnation on the back surface, and when used as a cushioning material in a vehicle, produced creaking noises when used with springs. The water repellency rating was also lower than that of the example. These results indicate that the reinforcing material of the example has an excellent effect of suppressing the seepage of foaming components.

[0042] Furthermore, Table 1 shows that the reinforcing materials of the Examples have lower elongation loads, higher tensile strengths, and higher elongation percentages at both room temperature (25°C) and high temperature (140°C) than the reinforcing materials of the Comparative Examples, demonstrating superior extensibility. In particular, the reinforcing materials of the Examples have lower loads at 75% elongation in tensile tests at high temperature (140°C) than the reinforcing materials of the Comparative Examples, and also have a larger difference between the load at 75% elongation and the tensile strength in tensile tests at high temperature (Example: 91.9 N / 5 cm, Comparative Example: 49.7 N / 5 cm). These results indicate that the reinforcing materials of the Examples have excellent moldability upon heating and shape retention upon cooling, resulting in excellent conformability to molds with deep irregularities, and thus can suppress exudation of foaming components even in foamed molded articles with deep irregularities.

Claims

1. a nonwoven fabric layer formed by entangling first staple fibers and second staple fibers; the first short fibers are binder short fibers, and at least a portion of the surface of the second short fibers has a water-repellent layer; A reinforcing material for foamed molded articles, which can be molded into a predetermined three-dimensional shape by press molding, and in which the blend ratio of the first staple fibers and the second staple fibers is (20 to 80) / (80 to 20).

2. 2. The reinforcing material according to claim 1, wherein the load at 75% elongation in a tensile test at high temperature is 100 N / 5 cm or less, and the difference between the load at 75% elongation in a tensile test at high temperature and the tensile strength is 60 N / 5 cm or more.

3. The reinforcing material according to claim 1 , wherein the foamed molded article is a cushioning material.

4. The reinforcing material according to any one of claims 1 to 3, wherein the second staple fibers are water-repellent staple fibers.

5. A molded article obtained by press-molding the reinforcing material according to claim 1.

6. A method for producing a molded article, comprising the steps of: heating the reinforcing material according to claim 1; and press-molding the heated reinforcing material.

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