Reinforcement material for foamed molded body, and molded body and method for manufacturing the molded body.

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 foamed molded body that can be molded into a predetermined three-dimensional shape by press molding, a molded body obtained by press molding the reinforcing material, and a method for manufacturing the molded body.

Background Art

[0002] As a cushion material for vehicle seats (seats) and the like, a foamed molded body such as foamed urethane is used. A reinforcing material may be disposed on the surface of such a foamed molded body. For example, in a cushion material for a vehicle seat, a reinforcing material including a non-woven fabric layer is disposed for the purpose of preventing a decrease in the rigidity of the cushion material and preventing frictional noise generated by friction between the cushion material and a spring (Patent Documents

[0003] When producing a foamed molded body, a reinforcing material is press-molded to obtain a molded body so as to match the shape of a mold for the foamed molded body. Then, the molded body is disposed in the mold, a foaming component is poured in, and the foaming component is foamed under heating and pressure to obtain a foamed molded body. When the foaming component is poured in or foamed, the foaming component may penetrate through the reinforcing material and bleed out. When such a foamed molded body with bleeding is used as a cushion material for a vehicle seat, there is a problem that frictional noise is generated due to friction between the bled-out foaming component and the spring.

[0004] As a reinforcing material for suppressing the bleeding of the foaming component during such molding, Patent Document 3 discloses a non-woven fabric composed of a mixed fiber of a crimpable composite short fiber and a water-repellent short fiber, wherein the mixing ratio of the water-repellent short fiber and the crimp composite short fiber is in the range of 3 / 97 to 40 / 60, and a urethane reinforcing material having a basis weight, a 50% elongation stress, and an elongation at break in a specific range is disclosed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] As described above, the reinforcing material is press-molded to match the shape of the mold for the foamed molded body. Therefore, the reinforcing material requires high extensibility so that it can be molded into a predetermined three-dimensional shape during press molding. In recent years, there has been a demand for foamed molded bodies with uneven surfaces, and when manufacturing such foamed molded bodies, molds with deep irregularities are used. In such molds with deep irregularities, if the reinforcing material does not conform well to the mold, it will not be possible to produce it with a uniform thickness, and the reinforcing material may become thin or tear in places, making it easy for the foaming components to seep out, or the reinforcing material and the foamed molded body may not be able to form the predetermined three-dimensional shape. Therefore, there is a need for a reinforcing material that can be used with molds with deep irregularities and that can suppress the release of foaming components.

[0007] Patent Document 3 does not mention forming the 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 of 1.0 to 15.0 N / 5 cm at 50% elongation. This characteristic indicates that the urethane reinforcing material stretches with a weak force. Considering these disclosures, it is thought that the urethane reinforcing material described in Patent Document 3 is formed in a single process of placement in the mold and molding with urethane, without prior formation into a predetermined three-dimensional shape by press molding. However, such a reinforcing material has the problem of poor conformability to mold irregularities, cannot be applied to molds with deep irregularities, and does not adequately suppress seepage in foamed molded articles with deep irregularities.

[0008] The present invention aims to provide a reinforcing material for a foamed molded article that is excellent in conforming to a mold, particularly to a mold with deep irregularities, and that can suppress the leakage of foaming components, as well as a molded article obtained by press-molding the reinforcing material and a method for manufacturing the molded article. [Means for solving the problem]

[0009] The reinforcing material of the present invention (hereinafter referred to as "this reinforcing material") is a reinforcing material for a foamed molded body that can be molded into a predetermined three-dimensional shape by press molding, and has a nonwoven fabric layer formed by the entanglement of first short fibers and second short fibers, wherein the first short fibers are binder short fibers, at least a portion of the surface of the second short fibers has a water-repellent layer, and the blending ratio of the first short fibers and the second short fibers is (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 reinforcing material. The method for manufacturing the molded article of the present invention includes the steps of heating the reinforcing material and press-molding the heated reinforcing material. [Effects of the Invention]

[0011] The reinforcing material and molded article of the present invention exhibit excellent conformability to molds, particularly to molds with deep irregularities, and can suppress the seepage of foaming components in foamed articles produced by such molds. The method for manufacturing the molded article of the present invention makes it possible to obtain a molded article with excellent conformability to molds. [Modes for carrying out the invention]

[0012] This reinforcing material has a nonwoven fabric layer formed by the entanglement of first short fibers and second short fibers. There are no particular limitations on the method of entangling the first short fibers and second short fibers, and known methods for manufacturing nonwoven fabrics can be applied. The first short fibers and second short fibers can usually be entangled by the needle punch method.

[0013] The first short fiber is a binder short fiber. In this reinforcing material, when it is formed into a predetermined three-dimensional shape by press molding, at least a portion of the binder component in the short fiber 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 short fibers are not particularly limited in their composition, as long as they contain a binder component that melts at least partially when heated, allowing them to partially bond the fibers constituting the nonwoven fabric. The binder short fibers are usually composed of two components: a high-melting-point component and a low-melting-point component that is the binder component. More specifically, for example, the binder short fibers may have a core-sheath structure composed of a core portion which is the high-melting-point component and a sheath portion which is the low-melting-point component.

[0015] When the binder short fibers contain both high-melting-point and low-melting-point components, there are no particular limitations on the mixing ratio of the two. The mixing ratio (by weight) of the high-melting-point and low-melting-point components is usually (30-70) / (70-30). It is preferable that the mixing ratio is within the above range because it provides high extensibility, especially at high temperatures, and makes it easier to conform to deep molds.

[0016] The term "low melting point" in the low melting point component refers to a melting point lower than the temperature at which press molding takes place, or a melting point of 90°C to 150°C. The term "high melting point" in the high melting point component refers to a melting point higher than the temperature at which press molding takes place, or a melting point of 200°C to 300°C.

[0017] The second short fiber has a water-repellent layer on at least a portion of its surface. There are no particular limitations on the method for forming the water-repellent layer. For example, the method involves entangling the first fiber and the second fiber and then applying a water-repellent treatment, or using a water-repellent short fiber as the second short fiber and entangling it with the first short fiber. The water-repellent short fiber is a fiber on which a water-repellent layer has been formed on at least a portion of its surface by applying a water-repellent treatment to the short fiber. For example, the water-repellent treatment may be a silicone treatment or a fluorine treatment.

[0018] There are no particular limitations on the material of the first and second short fibers. Examples of such materials include polyester, polyethylene, and polypropylene. The material is preferably polyester. The first and second short 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, if the binder short fiber is a fiber having a core-sheath structure, the core and the sheath may be made of the same material or different materials. Specifically, examples of the binder short fiber include short fibers composed of high-melting-point polyester and low-melting-point polyester, and in particular, short fibers composed of a core made of high-melting-point polyester and a sheath made of low-melting-point polyester.

[0019] The lengths of the first and second short fibers are usually 75 mm or less. There is no particular limit to the lower limit of the length, but it is usually 20 mm or more, preferably 30 mm or more. When the length is within the above range, it is preferable that the entanglement of the first and second short fibers is increased and the tensile strength of the nonwoven fabric layer is improved. The fiber diameter of the first and second short fibers is usually 8 dtex or less, preferably 4 dtex or less. There is no particular limit to the lower limit of the fiber diameter, but it is usually 3 dtex or more. The lengths and / or fiber diameters of the first and second short 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). Note that the upper and lower limits of the blending ratio can be any integer value within the above numerical range. If the first short fiber is excessive, the reinforcing material may adhere to the mold during press molding, which is not preferable. If the first short fiber is too little, the rigidity after press molding may be insufficient, and the three-dimensional shape of the foamed molded body may become unstable, which is not preferable.

[0021] There is no particular limitation on the blending ratio of the first and second short fibers in the fiber raw material, and it can be set within an appropriate range. The blending ratio (by weight) of the first and second short fibers is usually, independently of each other, 20 - 80%, preferably 30% - 70%, and more preferably 30 - 65%. Note that the upper and lower limits of the blending ratio can be any integer value within the above numerical range.

[0022] By having the above configuration, this reinforcing material has high extensibility, particularly high extensibility at high temperatures, and excellent formability during heating and shape retention during cooling. Specifically, this reinforcing material preferably has a load at 75% elongation in the tensile test at high temperature of 100 N / 5 cm or less, preferably 90 N / 5 cm or less. Also, this reinforcing material preferably has a difference between the load at 75% elongation and the tensile strength in the tensile test at high temperature 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 range, the extensibility at high temperature is high, and the followability is excellent even in a mold with deep unevenness. As a result, in the foamed molded body obtained by a mold with deep unevenness, bleeding of the foaming component can be suppressed, which is preferable. Note that the "load at 75% elongation and tensile strength" in the tensile test at high temperature is the value measured by the method and conditions of the tensile test at 140°C described in the section of the examples.

[0023] The load at 5% elongation of this reinforcing material is preferably 10 N / 5 cm or more, and preferably 15 N / 5 cm or more. A load at 5% elongation within the above range is preferable because it allows the reinforcing material to be automatically inserted into the mold by machine during press forming. Note that the "load at 5% elongation" is the 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 appropriately adjusted by the proportion of binder short fibers in the raw fiber, the punch density in the entanglement by the needle punching method, and the needle depth. For example, increasing the proportion of binder short fibers in the raw fiber will decrease the load at 75% elongation and increase the difference between the load at 75% elongation and the tensile strength. Also, increasing the punch density and needle depth in the entanglement by the needle punching method will 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 and second short fibers, as long as they do not hinder the effects of the present invention. Examples of such other fibers include known antibacterial fibers, flame-retardant fibers, and moisture-absorbing, heat-generating fibers. The proportion (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 proportion can be any integer values ​​within the above numerical range.

[0026] The reinforcing material has a nonwoven fabric layer formed by the entanglement of the first and second short fibers. The reinforcing material may consist only of the nonwoven fabric layer, or it may include other layers as long as they do not hinder the function of the present invention. There are no particular limitations on the basis weight, thickness, and air permeability of the nonwoven fabric, and they can be set to appropriate values ​​as needed. The basis weight of the nonwoven fabric is usually 80 to 150 g / m². 2 Preferably 100-140 g / m 2 The aforementioned air permeability is typically 120-200 cm. 3 / (cm 2 • s), preferably 140-180cm 3 / (cm 2 ·s). The upper and lower limits of the basis weight and air permeability can be any integer values ​​within the above numerical range. 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 values. The air permeability is a value measured based on the JIS L1906 Frazier method.

[0027] There are no particular limitations on the material and type of the foamed molded body. For example, urethane can be used as the material of the foamed molded body. More specifically, examples of the foamed molded body include cushioning material, and more specifically, cushioning material for vehicle seats. The foamed molded body can usually be obtained by press-molding the reinforcing material to match the shape of a mold for foamed molded bodies, placing the molded body in the mold, pouring in a foaming component, and then allowing the foaming component to foam.

[0028] The molded body is obtained by press forming the reinforcing material. The method and conditions of the press forming are not particularly limited, as long as the reinforcing material can be formed. The press forming is usually press forming using a die. The press forming may also be cold press forming (press forming in which the material is heated) or hot press forming (press forming in which the die is heated). Specifically, the molded body can be obtained by a method that includes, for example, the steps of heating the reinforcing material and press forming the heated reinforcing material. [Examples]

[0029] The present invention will be specifically described below with reference to examples. However, 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 invention, depending on the purpose and application.

[0030] 1. Manufacturing of reinforcing materials The following fibers were used as raw materials. (1) Binder fibers A two-component 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-point polyester fiber (melting point: 260°C) treated with a fluorine-based oil for water repellency (thickness: 2.0 dtex, length: 5.1 cm). (3) Other fibers High melting point polyester fiber (melting point: 260℃) (thickness: 2.0 dtex, length: 5.1 cm).

[0031] A web was prepared by passing the raw fibers, consisting of (1) binder fibers, (2) water-repellent fibers, and (3) other fibers, through a carding machine. The webs were laminated in a cross layer to produce a laminated web. The laminated web was needle-punched to entangle the fibers, thereby producing the reinforcing material of the embodiment, which is a needle-punched nonwoven fabric. The blending ratio (by weight) of the (1) binder fibers, (2) water-repellent fibers, and (3) other fibers is shown in Table 1.

[0032] The comparative example's reinforcing material was prepared in the same manner as the example, except that (1) binder fibers and (3) other fibers were used as raw material fibers. The blending ratio (by weight) of the (1) binder fibers and (3) other fibers is 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 investigated at 25°C and 140°C using a tensile testing machine (Autograph AGS-5kNX, manufactured by Shimadzu Corporation). The results are shown in Table 1.

[0035] Tensile tests at 25°C were performed according to the following procedure. Rectangular test specimens 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 in Japanese Patent Publication No. 2023-106813). Two test specimens were prepared: one with the longitudinal direction (tensile direction) being the flow direction of the manufacturing process (hereinafter referred to as the "MD direction"), and another with the longitudinal direction being perpendicular to the MD direction (hereinafter referred to as the "CD direction"). Chucks with a width of 20 mm were attached to both ends of the test specimens, and they were set to have a gauge length of 100 mm. Tensile tests were performed at a tensile speed of 100 mm / min, and the tensile strength (N / 50 mm) when the test specimens were stretched to 5%, 30%, 50%, 75%, and 100%, as well as the tensile strength (N / 50 mm) and elongation at break (mm), were measured. A total of six tensile tests were performed: three in the MD direction and three in the CD direction. The arithmetic mean of these six measurements was used as the tensile strength (maximum load) and elongation at break. The elongation rate φ (%) was calculated using the formula φ = {(L-L0) / L0} × 100, where L0 (=100 mm) was the gauge length before the test and L was the gauge length after the break (elongation at break).

[0036] The tensile test at 140°C was performed according to the following procedure (see Figure 5 in Japanese Patent Publication No. 2023-106813). A rectangular test piece measuring 200 mm in length and 50 mm in width was cut from the reinforcing material of the example and comparative example using the same method as the tensile test at 25°C. Two hair irons were prepared, each having a pair of clamping parts with a clamping part width of 25 mm. The two hair irons were placed adjacent to each other and fixed in place with fasteners to prevent them from separating. The total width of the clamping parts was 50 mm. A cushion sheet was attached to the inside of the clamping parts so that when the pair of clamping parts were closed, they would not touch, and a gap of 3 mm to 5 mm would be formed between them. The center of the test piece set in the tensile testing machine was clamped between the two hair irons heated to 140°C and held for 10 seconds. As mentioned above, the total width of the clamping parts is 50 mm, so the test piece will also be heated over a width of 50 mm. Furthermore, because there is a gap between the pair of clamping parts, each clamping part of the hair iron does not come into contact with the test specimen. After 10 seconds, with the test specimen still clamped in the hair iron, 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 tests were conducted in accordance with "JIS L 1092 Spray Test". The number of tests for both the example and comparative example was N=3.

[0038] D. Urethane seepage evaluation The reinforcing materials of the examples and comparative examples were press-molded to match the shape of a mold for foamed molded bodies (a shape suitable for the area near the headrest stay mounting point on the back of the front seat of an automobile). Then, the molded reinforcing materials were placed in the mold for foamed molded bodies, and urethane, the foaming component, was poured in. The foaming component was then foamed under heat and pressure to produce the foamed molded bodies of the examples and comparative examples, which serve as cushioning materials. The manufactured foamed molded bodies (N=5) were visually inspected for any leakage of the reinforcing material to the back surface. Furthermore, the foamed molded bodies were placed near the headrest stay mounting point on the back of the front seat of an automobile, and creaking sounds were detected by pressing a person's hand or body against the foamed molded body. 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, measurement results for "100% elongation load" are not available.

[0041] 3.Results Table 1 shows that in the example's reinforcing material, no urethane impregnation to the back surface was observed, and no squeaking noise occurred with the spring. In contrast, in the comparative example's reinforcing material, urethane impregnation to the back surface was observed, and when placed in a vehicle as a cushioning material, squeaking noise occurred with the spring. Furthermore, the water-repellent rating was lower than that of the example. These results indicate that the example's reinforcing material has a superior effect in suppressing the seepage of foaming components.

[0042] Furthermore, as can be seen from Table 1, the reinforcing material of the example exhibits lower elongation load, higher tensile strength and elongation, and superior stretchability compared to the reinforcing material of the comparative example, both at room temperature (25°C) and high temperature (140°C). In particular, the reinforcing material of the example exhibits a lower 75% elongation load in the high-temperature (140°C) tensile test than the reinforcing material of the comparative example, and a larger difference between the 75% elongation load and tensile strength in the high-temperature tensile test (Example: 91.9 N / 5cm, Comparative Example: 49.7 N / 5cm). This result indicates that the reinforcing material of the example exhibits excellent moldability upon heating and shape retention upon cooling, and as a result, excellent conformability to molds with deep irregularities, thus suppressing the seepage of foam components even in foamed molded articles with deep irregularities.

Claims

1. It has a nonwoven fabric layer formed by the entanglement of first short fibers and second short fibers, The first short fiber is a binder short fiber, and at least a portion of the surface of the second short fiber has a water-repellent layer. The blending ratio of the first short fiber and the second short fiber is (20-80) / (80-20), A reinforcing material for a foamed molded body that can be molded into a predetermined three-dimensional shape by press molding, wherein the load at 75% elongation in a high-temperature tensile test is 90 N / 5 cm or less, and the difference between the load at 75% elongation in a high-temperature tensile test and the tensile strength is 80 N / 5 cm or more.

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

3. The reinforcing material according to claim 1 or 2, wherein the second short fiber is a water-repellent short fiber.

4. A molded body obtained by press-forming the reinforcing material described in claim 1.

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

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