Flame retardant synthetic leather

Abstract

To provide a vehicle interior synthetic leather, which is formed by considering CO2 emission during manufacture and reducing used amount of chemical material, and has flame retardant property satisfying FMVSS combustion standard for vehicle interior material without using fire retardant.SOLUTION: A flame retardant synthetic leather 1 is a vehicle interior synthetic leather formed of a surface top coat layer 2, a resin layer 3, an adhesive layer 4, and a base fabric layer 5, and includes powder cellulose at least in the adhesive layer 4. Combustion speed of the flame retardant synthetic leather is 102 mm / min or less in combustion test based on FMVSS (Federal Motor Vehicle Safety Standards).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to flame-retardant synthetic leather. [Background technology]

[0002] Synthetic leather is widely used as an interior covering for automobiles, trains, buses, airplanes, etc. In particular, its use as an interior covering for automobiles is expanding from luxury cars to SUVs and minicars because it can create a luxurious atmosphere inside the vehicle. To be used as an interior covering for automobiles, synthetic leather must have surface strength such as abrasion resistance, durability such as light resistance and heat resistance, satisfy the legal FMVSS flammability standards, and also be soft to the touch and flexible.

[0003] Furthermore, from the perspective of environmental conservation and reducing CO2 emissions during manufacturing, there is a demand to reduce the amount of chemical substances used in automotive interior skin materials.

[0004] One known method for imparting flame retardancy or flame retardancy to synthetic leather is to add a flame retardant to at least one of the surface resin layer, adhesive layer, and base fabric layer that make up the synthetic leather. Traditionally, halogen compounds have been used as flame retardants, but in recent years, metal hydroxides, which suppress the generation of harmful gases during combustion, and organic phosphoric acid compounds, which address the issue of water resistance, have been considered preferable (Patent Document 1).

[0005] Also disclosed is a flame-retardant resin composition containing a nanocellulose-based material, a phosphorus-based flame retardant, and a resin consisting of at least one of a thermoplastic resin and a thermosetting resin. Adding nano-dispersed cellulose material made from wood pulp increases the resin strength, promotes carbonization during combustion, and forms a carbonized layer, enhancing the flame-retardant effect. However, as with Patent Document 1, a phosphorus-based flame retardant is also used. (Patent Document 2)

[0006] Synthetic leather for automotive interiors has a laminated structure consisting of a surface top coat layer, a resin layer, an adhesive layer, and a substrate layer, and is used as a composite material with a soft urethane foam or backing fabric material laminated to the back side. Each layer requires the use of a flame retardant, and since combustion behavior varies depending on the flame retardant and material used, even if the flammability of each layer alone is good, the flammability of the composite may not be satisfactory. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] WO2013 / 187492 [Patent Document 2] Patent Publication No. 2020-70332 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention aims to provide synthetic leather for automobile interiors that has flame retardant properties that satisfy the FMVSS flammability standards for automobile interior materials without using flame retardants, while taking into consideration CO2 emissions during production and aiming to reduce the amount of chemical substances used. [Means for solving the problem]

[0009] [1] A synthetic leather for automobile interiors, comprising a surface top coat layer, a resin layer, an adhesive layer, and a base fabric layer, Flame-retardant synthetic leather characterized by containing powdered cellulose in at least the adhesive layer and having a burning rate of 102 mm / min or less in a flammability test in accordance with FMVSS (Ferritts-Masseur-Volkswagen-Schutz-Verlag).

[0010] [2] The flame-retardant synthetic leather according to the above item 1, wherein the blending amount of the powdered cellulose is 5 to 30 parts by mass per 100 parts by mass of the resin component contained in the adhesive layer.

[0011] [3] The flame-retardant synthetic leather according to the above item 1 or 2, wherein the powdered cellulose has an average particle size of 5 μm to 500 μm.

[0012] [4] The flame-retardant synthetic leather according to the preceding paragraph 1, wherein the resin component of the adhesive layer is a water-based polyurethane resin. [Effects of the Invention]

[0013] In the invention of [1], powdered cellulose is included in at least the adhesive layer of the synthetic leather for automobile interiors, which promotes carbonization during combustion and provides a flame retardant effect, thereby meeting the FMVSS flammability standards. By adding powdered cellulose to the adhesive layer, it also acts as a filler, reducing the amount of resin contained in the adhesive layer and preventing a decrease in adhesive strength through its anchoring effect.

[0014] Since there is no need to add metal hydroxides or phosphorus-based flame retardants, the environmental impact is small, and the flame retardancy achieved by promoting carbonization and creating a gas barrier does not adversely affect the flammability of other laminated materials.

[0015] Powdered cellulose is produced by separating and refining plant-derived cellulose fibers, and compared to conventional flame retardant specifications, it can contribute to reducing CO2 emissions during manufacturing and also leads to a reduction in the amount of chemical substances used. On the other hand, there is a risk of decomposition over time, but this can be prevented by including it in the adhesive layer, which is not exposed on the surface.

[0016] In the invention [2], the blending amount of the powdered cellulose is 5 to 30 parts by mass per 100 parts by mass of the resin component contained in the adhesive layer, so that the synthetic leather also has the physical properties required for automobile interiors, such as abrasion resistance and peel strength.

[0017] In the invention [3], the average particle size of the powdered cellulose is 5 μm to 500 μm, so that it has good compatibility with the resin component contained in the adhesive layer and also has the abrasion resistance and peel strength that are physical properties required for synthetic leather for automobile interiors.

[0018] In the invention [4], the resin component of the adhesive layer is a water-based polyurethane resin, which has good affinity with the powdered cellulose and allows it to be dispersed uniformly. As a synthetic leather for automobile interiors, it has excellent touch, flexibility, and durability. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic diagram of one embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] An embodiment of the synthetic leather for automobile interiors according to the present invention will be described with reference to the drawings.

[0021] The synthetic leather 1 for automobile interiors according to the present invention is formed by laminating a surface top coat layer 2, a resin layer 3, an adhesive layer 4, and a base fabric layer 5 in this order, and is characterized in that at least the adhesive layer 4 contains powdered cellulose and has flame retardancy.

[0022] The base fabric layer 5 is preferably a fiber fabric such as a woven or knitted fabric or a nonwoven fabric made of a conventionally known fiber material such as synthetic fiber or natural fiber. Fibers colored with dyes or pigments may be used as needed. Of these, for automotive applications, woven or knitted fabrics made of polyester fiber are preferred in terms of weather resistance. As woven or knitted fabrics, knitted fabrics are preferred, and warp knitted fabrics and circular knitted fabrics are particularly preferred. From the perspective of texture, knitted fabrics may be subjected to a nap-raising process.

[0023] The adhesive layer 4 is provided to improve the adhesion between the resin layer 3 and the fabric layer 5. Examples of resins that can be used to form the adhesive layer 4 include polyurethane resins, vinyl acetate resins, and acrylic resins. Of these, water-based polyurethane resins are preferred. Water-based polyurethane resins also have good affinity with powdered cellulose. From the perspective of texture, the adhesive layer 4 may be a foamed layer, and foaming methods include well-known techniques such as physical foaming and chemical foaming.

[0024] The adhesive layer 4 is characterized by containing powdered cellulose. The blending amount of the powdered cellulose is preferably 5 to 30 parts by mass per 100 parts by mass of the resin component contained in the adhesive layer 4. If it is 5 parts by mass or less, there is a risk that the flame retardancy will not be achieved, and if it is 30 parts by mass or more, there is a risk that the adhesive strength will decrease and the peel strength will deteriorate, which is not preferable.

[0025] The type of powdered cellulose is not critical. Commercially available powdered cellulose made from wood pulp can be used. Examples of commercially available powdered cellulose include KC Flock manufactured by Nippon Paper Industries Co., Ltd. The average particle size of the powdered cellulose is preferably 5 μm to 500 μm. Nano-sized powdered cellulose with an average particle size of 5 μm or less can be used, but because of the labor required for handling and uniform dispersion, an average particle size of 5 μm or more is preferred. Furthermore, powdered cellulose with an average particle size of 500 μm or more is undesirable because its dispersibility in the resin deteriorates, potentially reducing the peel strength between the resin layer 3 and the fabric layer 5. In this specification, "average particle size" refers to the particle size at 50% of the cumulative value in the particle size distribution determined by laser diffraction / scattering. Specifically, the measurement was performed using a particle size distribution analyzer MT3000 manufactured by Microtrac.

[0026] The powdered cellulose can be dispersed in a resin by dispersing it in water, for example, or by mechanical stirring, since the water-based resin used provides good dispersibility. Additives such as a dispersant and an antifoaming agent may be used as needed.

[0027] The type of resin used in the resin layer 3 is a polyurethane resin used in synthetic leather. There are no particular limitations on the polyurethane resin, and examples include polycarbonate polyurethane resin, polyester polyurethane resin, polyether polyurethane resin, and polycaprolactone polyurethane resin. Among these, polycarbonate polyurethane resin is preferred from the viewpoints of abrasion resistance, weather resistance, and hydrolysis resistance, and a combination of two or more types can also be used.

[0028] The resin layer 3 may also contain powdered cellulose, similar to that of the adhesive layer 4. The amount of powdered cellulose added is preferably 0 to 30 parts by mass per 100 parts by mass of the resin component of the resin layer 3. An amount of 30 parts by mass or more is not preferred because it may cause a decrease in surface physical properties such as abrasion resistance. The dispersion method is the same as that for the adhesive layer 4.

[0029] The flame-retardant synthetic leather of the present invention is characterized in that at least the adhesive layer 4 contains powdered cellulose.

[0030] Furthermore, a colored layer such as a print may be provided between the resin layer 3 and the surface top coat layer 2 as needed. Examples of printing methods include inkjet printing and screen printing, and examples of printing inks include dyes and pigments.

[0031] The surface top coat layer 2 is provided for the purpose of improving durability such as abrasion resistance, and improving functionality such as antifouling properties and antibacterial properties. The surface top coat contains a resin, and examples of the resin include polyurethane resin, acrylic resin, and silicone resin. Functional agents such as antifouling agents, antibacterial agents, and antistatic agents may be added as necessary. [Example]

[0032] Next, examples of the present invention will be described, but the present invention is not limited to these examples and can be applied within the scope of the present specification.

[0033] Preparation of the [Base Fabric Layer] Polyester tricot knit fabric, 280g / m 2 A black base fabric was prepared by dyeing with the concentrate.

[0034] Preparation of the resin layer A polycarbonate-based water-based polyurethane resin, product number HYDRAN WLS-250, manufactured by DIC Corporation, was prepared.

[0035] Preparation of the adhesive layer A polycarbonate-based water-based polyurethane resin, product number HYDRAN WLA-515AR, manufactured by DIC Corporation, was prepared.

[0036] Preparation of the [Surface Top Coat Layer] Polycarbonate-based water-based polyurethane resin, manufactured by Dainichiseika Chemicals Co., Ltd., product number: Lezamin D-5505G (gloss type) / Lezamin D-5506HM (matt type) = 1:2 mixture was prepared.

[0037] [Preparation of powdered cellulose] Commercially available powdered cellulose with an average particle size ranging from 5 μm to 700 μm was prepared, including wood cellulose microfine products: Nippon Paper Industries Co., Ltd., product number KC Flock W-10MG2, average particle size 10 μm, and Rengo Co., Ltd., product number Viscopal D-3, average particle size 6.5 μm.

[0038] Flame-retardant synthetic leather can be produced by a well-known method. For example, an 80 μm-thick resin layer is formed on a release paper with a release layer and a textured pattern (R-86M PXDH, manufactured by Lintec Corporation) using a comma coater, and then attached to a base fabric layer via an adhesive layer. After that, a surface top coat layer is formed using a gravure coater to produce synthetic leather.

[0039] Example 1 Using the materials prepared in the previous sections

[0033] to

[0038] , the powdered cellulose had an average particle size of 24 μm and was blended in an amount of 7 parts by mass per 100 parts by mass of the resin component contained in the adhesive layer, and synthetic leather for automobile interiors was obtained by the method described above.

[0040] <Examples 2 to 6 and Comparative Examples 1 to 4> The blending ratio, average particle size, and additive layer of the powdered cellulose were set as shown in Table 1, and synthetic leather for automobile interiors was obtained in the same manner as in Example 1.

[0041] [Table 1]

[0042] The synthetic leather obtained as described above was evaluated according to the following methods.

[0043] <Peel strength> Peel strength was measured to measure the adhesive strength between the adhesive layer and the base fabric layer. A tensile tester conforming to JIS L1069 was used. Five samples measuring 30mm x 120mm were taken in both the warp and weft directions, and the samples were peeled 40mm parallel to the short side as the grip between the skin layer and the base fabric, and the peel strength was measured using the tensile tester. A minimum value of 24.5N or more in both the warp and weft directions was considered a pass.

[0044] <Taber abrasion resistance> Abrasion strength was measured to measure surface strength. A Taber abrasion tester conforming to JIS L1069 was used. A 120mm diameter sample was taken and subjected to 2000 abrasion tests using the CS-11 abrasion wheel with a load of 9.8N. The abrasion condition was graded based on the degree of surface abnormality, with grade 4 or above being considered a pass. Grade 5: No abnormalities are found Grade 4: Slight abnormalities are observed but are not noticeable Grade 3: Abnormalities are clearly observed Grade 2: Significant abnormalities are observed Grade 1: Significant abnormality

[0045] <Flammability> Evaluation of flame retardancy. A flammability tester conforming to FMVSS (US Motor Vehicle Safety Standards) is used. With the test piece (approximately 350 x 100 mm) held horizontally, a 38 mm high flame is applied for 15 seconds, and the burning rate is measured between the 254 mm marked lines when the ignited flame extends beyond the 38 mm line from the edge. Five samples are taken both vertically and horizontally, and the worst data of 102 mm / min or less is considered a pass.

[0046] [Table 2]

[0047] <Additional Evaluation> Considering the actual usage pattern, a surface layer was made of the synthetic leather of Example 1, and a soft urethane foam and a backing fabric material were laminated in this order on the back side to form a cushioning layer. The flammability was evaluated as described in

[0044] . The soft urethane foam was manufactured by Inoac Corporation, product number: EL-67F, 5.0 mm thick, and the backing fabric material was 40 g / m2. 2 The polyester circular knit fabric was used. The lamination method was flame lamination. The burn rate of the laminate was 65mm / min vertically and 58mm / min horizontally, which was acceptable.

[0048] As shown in Table 2, in Examples 1 to 6, the powdered cellulose had an average particle size of 5 μm to 500 μm, and the amount of powdered cellulose was at least 5 to 30 parts by mass per 100 parts by mass of the resin component contained in the adhesive layer, so that the materials had flame retardancy and durability sufficient for use in automotive interiors. Furthermore, additional evaluation revealed that the materials were flame retardant even when laminated with a cushioning layer, which is the actual usage pattern, and therefore laminating materials with materials that have different combustion behaviors did not adversely affect flammability. On the other hand, the synthetic leathers of Comparative Examples 1 to 4 failed to satisfy the flammability or surface durability requirements. [Industrial Applicability]

[0049] It can be suitably used as synthetic leather for automobile interiors. [Explanation of symbols]

[0050] 1...Slow-flaming synthetic leather 2. Surface top coat layer 3. Resin layer 4...adhesive layer 5...Base fabric layer

Claims

1. A synthetic leather for automobile interiors, comprising a surface top coat layer, a resin layer, an adhesive layer, and a base fabric layer, A flame-retardant synthetic leather characterized in that at least the adhesive layer contains powdered cellulose, and that the burning rate is 102 mm / min or less in a flammability test in accordance with FMVSS (Ferritts Vehicle Safety Standards).

2. 2. The flame-retardant synthetic leather according to claim 1, wherein the blending amount of the powdered cellulose is 5 to 30 parts by mass per 100 parts by mass of the resin component contained in the adhesive layer.

3. 3. The flame-retardant synthetic leather according to claim 1, wherein the powdered cellulose has an average particle size of 5 μm to 500 μm.

4. 2. The flame-retardant synthetic leather according to claim 1, wherein the resin component of the adhesive layer is a water-based polyurethane resin.

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