Anti-yellowing automotive interior leather

Abstract

The invention provides yellowing-resistant automotive interior leather which comprises a polyolefin base material layer composed of an ethylene-alpha olefin copolymer, ethylene propylene diene monomer and an auxiliary agent, the crosslinking degree of the polyolefin base material layer is larger than 30%, and the auxiliary agent comprises one or more of a hindered phenol antioxidant, a thioester antioxidant, a hydroxylamine antioxidant and a hindered amine antioxidant. An ethylene propylene diene monomer and ethylene-alpha olefin copolymer cross-linking system is used as an interior leather base material, a plasticizer or a solvent is not contained, and small molecular substances are not separated out or volatilized. Through model selection and compounding of the antioxidant, the problem of yellowing caused by thermal aging and light aging in the use process of the polyolefin interior leather is effectively solved. The polyolefin base material layer has a crosslinking degree of not less than 30% through an electron beam irradiation process, the compatibility of the polyolefin leather base material and a micromolecular antioxidant is improved by a network structure formed in the base material layer, and the problem of precipitation is not generated after long-term use.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of automotive interior leather, and particularly relates to a yellowing-resistant automotive interior leather. BACKGROUND

[0002] Automotive interior leather is an important component of automotive interior, and is widely used in seats, door panels, center consoles and other parts. With the promotion and large-scale application of new energy vehicles, the requirements for environmental protection, comfort, weather resistance and other properties of automotive interior leather are continuously improved. Currently, the commonly used artificial leather materials mainly include polyvinyl chloride (PVC) artificial leather, polyurethane (PU) artificial leather and thermoplastic elastomer (TPO) artificial leather.

[0003] However, the existing artificial leather materials have certain deficiencies in environmental protection. PVC artificial leather uses a large amount of plasticizer, and PU artificial leather also needs to use solvents in the preparation process. In recent years, thermoplastic polyolefin (TPO) skin is usually used to replace traditional PVC and PU leather to reduce VOC emissions.

[0004] At present, light-colored interior leather is gradually becoming a new favorite in the market. Such leather needs to have long-term stable heat yellowing resistance and light yellowing resistance, and the yellowing resistance directly affects the appearance and service life of the interior leather. Therefore, how to improve the yellowing resistance of automotive interior leather has become an important research direction in the field of automotive interior material technology.

[0005] In order to solve the yellowing problem of yellowing-resistant automotive interior leather, CN100537653C solves the problem of decomposition of traditional ABS / PVC materials at high temperatures to produce harmful substances by forming a polyolefin elastomer material through crosslinking reaction, realizes the improvement of weather resistance and the environmental protection of automotive interior materials, and to a certain extent, improves the yellowing resistance of the yellowing-resistant automotive interior leather, but it is difficult to meet the requirements of light-colored leather on yellowing resistance. SUMMARY

[0006] The present application provides a yellowing-resistant automotive interior leather, which comprises a polyolefin base layer, the polyolefin base layer is composed of ethylene-alpha olefin copolymer, ethylene-propylene rubber and additives, the crosslinking degree of the polyolefin base layer is greater than 30%, and the additives include an antioxidant, the antioxidant is one or more of hindered phenolic antioxidants, hydroxylamine antioxidants, hindered amine antioxidants and thioester antioxidants.

[0007] Further, the polyolefin base layer includes 100 parts of ethylene-alpha olefin copolymer and ethylene-propylene rubber in total, wherein the ethylene-alpha olefin copolymer is 40-90 parts, the ethylene-propylene rubber is 10-60 parts, and the additives are 0.1-10 parts, and the antioxidant is 0.1-0.6 parts.

[0008] Further, the auxiliary agent comprises 0.1-0.6 parts of an antioxidant, 0.1-0.5 parts of a coupling agent, 0.08-5 parts of a crosslinking auxiliary agent, and 0-5 parts of a polyethylene color master batch.

[0009] Further, the antioxidant is a hindered amine antioxidant.

[0010] Further, the antioxidant is a combination of a hindered amine antioxidant and a hydroxylamine antioxidant.

[0011] Further, the weight ratio of the hindered amine antioxidant and the hydroxylamine antioxidant is greater than or equal to 1 and less than or equal to 3.

[0012] Further, the antioxidant is the hindered phenol antioxidant.

[0013] Further, the antioxidant is a combination of a hindered phenol antioxidant and a thioester antioxidant.

[0014] Further, the weight ratio of the hindered phenol antioxidant and the thioester antioxidant is greater than or equal to 1 and less than or equal to 3.

[0015] Compared with the prior art, the technical scheme has the following beneficial effects:

[0016] The ternary ethylene-propylene rubber and ethylene-alpha olefin copolymer crosslinking system is used as the interior leather substrate, and does not contain plasticizers or solvents, and does not precipitate or volatilize small molecular substances.

[0017] Through the selection and compounding of the antioxidant, the yellowing problem of the polyolefin interior leather due to thermal aging and light aging during use is effectively solved.

[0018] Through the electron beam irradiation process, the polyolefin substrate layer has a crosslinking degree of not less than 30%, and the network structure formed in the substrate layer improves the compatibility of the polyolefin leather substrate with the small molecular antioxidant, and does not produce precipitation problems during long-term use. DETAILED DESCRIPTION

[0019] In order to make the invention purposes, technical schemes and beneficial technical effects of the present application clearer, the present application will be described in detail below in combination with specific embodiments. It should be understood that the embodiments described in the specification are only for the purpose of explaining the present application, and are not intended to limit the present application.

[0020] For simplicity, only some numerical ranges are explicitly recited herein. However, any lower limit can be combined with any upper limit to form a range not explicitly recited; and any lower limit can be combined with any other lower limit to form a range not explicitly recited, and likewise any upper limit can be combined with any other upper limit to form a range not explicitly recited. Furthermore, although a range is recited, every point or individual number within that range is to be included in the range, even though the exact point or number is not explicitly recited. Thus, every point or individual number can be combined as the lower limit or the upper limit with any other point or individual number or with other lower or upper limits to form a range not explicitly recited.

[0021] In the description herein, it is to be understood that, unless otherwise specified, "above" and "below" are inclusive of the stated number, and "a plurality" of "a plurality" means two or more.

[0022] The above summary of the application does not necessarily describe every disclosed embodiment or implementation of the application. The description which follows more particularly exemplifies illustrative embodiments. In several places throughout the application, guidance is provided through a series of examples, which can be used in various combinations. In each of the various examples, the recited combination is meant to be representative only, and should not be interpreted as an exhaustive list of combinations.

[0023] The present application provides a yellowing-resistant automotive interior leather, comprising a polyolefin substrate layer, the polyolefin substrate layer is composed of ethylene-alpha olefin copolymer, ethylene-propylene rubber and additives, the crosslinking degree of the polyolefin substrate layer is greater than 30%, the melting point of the ethylene-alpha olefin copolymer is greater than 60℃, and the additives include an antioxidant, the antioxidant is one or more of a hindered phenolic antioxidant, a hydroxylamine antioxidant, a hindered amine antioxidant and a thioester antioxidant.

[0024] In some embodiments, the additives are dispersed in a blend of the ethylene-alpha olefin copolymer and the ethylene-propylene rubber, and the ethylene-propylene rubber is dispersed as a dispersed phase inside a continuous phase of the ethylene-alpha olefin copolymer.

[0025] The automotive interior leather provided by the present application uses polyolefin as the substrate. The polyolefin material has a relatively low price and generates very little odor volatile matter, and compared with solvent-type PU automotive interior leather and PVC automotive interior leather added with plasticizers, the automotive interior leather produced by the present application has lower odor and has better environmental protection performance in the production process, thereby meeting the requirements of higher odor and environmental protection in some occasions.

[0026] In some embodiments, the thickness of the polyolefin substrate layer is 50-800 microns.

[0027] In some embodiments, the polyolefin substrate layer comprises a polyolefin substrate layer and an adhesive layer, the thickness of the polyolefin substrate layer is 50-500 microns, and the thickness of the adhesive layer is 10-300 microns.

[0028] In some embodiments, the ethylene-a-olefin copolymer used in the polyolefin substrate layer and the ethylene-a-olefin copolymer used in the polyolefin tie layer are the same or different polyolefin elastomers, both of which are copolymers of ethylene and a-olefins (such as 1-butene, 1-hexene, 1-octene, etc.) prepared by coordination polymerization or metallocene catalyzed polymerization.

[0029] The ethylene-a-olefin copolymer used in the present application is a polyolefin elastomer formed by copolymerization of ethylene and a high content (>20%) of a-olefins (such as 1-octene). The a-olefin content is generally in the range of 20% to 40%; the crystalline regions of polyethylene segments act as physical crosslinking points, and the longer branches introduced by a-olefins make the amorphous copolymer form a rubber phase, combining the properties of plastic and rubber; compared with propylene elastomers, ethylene elastomers are more elastic and softer.

[0030] In some embodiments, the terpolymer is a copolymer of ethylene, propylene and a third monomer, the third monomer having a non-conjugated diene structure, containing a third monomer that can participate in polymerization in the terpolymer, providing crosslinking active sites for irradiation crosslinking. The third monomer includes ethylidene norbornene, dicyclopentadiene, 1,4-hexadiene, and preferably ethylidene norbornene; the use of a terpolymer with an appropriate content of the third monomer helps to increase the crosslinking density and crosslinking speed of the polyolefin substrate.

[0031] The ethylene-a-olefin copolymer and the terpolymer have similar polarity and form a uniformly dispersed structure by melt blending; in the processing process, by selecting the ratio of the two materials and the processing conditions, the ethylene-a-olefin copolymer is used as the continuous phase and the terpolymer is used as the dispersed phase to form a blending system, and through irradiation crosslinking, the third monomer in the terpolymer and the active groups of the crosslinking aid in the system form active crosslinking sites, forming a network crosslinking inside the ethylene-a-olefin copolymer, inside the terpolymer, and at the interface between the terpolymer and the first ethylene-a-olefin copolymer.

[0032] In some embodiments, based on 100 parts by weight of the ethylene-a-olefin copolymer and the terpolymer, the polyolefin substrate layer further comprises 0.1 to 10 parts of an aid.

[0033] In some embodiments, based on 100 parts by weight of the ethylene-a-olefin copolymer and the terpolymer, the polyolefin substrate layer further comprises 0.1 to 0.6 parts of an antioxidant.

[0034] In some embodiments, the antioxidant is a hindered amine antioxidant. Hindered amine antioxidants terminate free radical chain reactions by capturing free radicals and converting them to stable imine and amine oxide. It does not quench free radicals by providing hydrogen atoms, but by capturing free radicals and converting them to stable species.

[0035] In some embodiments, the antioxidant is a low molecular weight monomeric hindered amine or a high molecular weight polymeric hindered amine with a 2,2,6,6-tetramethylpiperidine skeleton, such as one of Tinuvin 770, Chimassorb 944, Tinuvin 622, Cyasorb UV-3346.

[0036] Hydroxylamine antioxidant molecules contain a hydroxylamine group (>N-OH) as a hindered alkyl or hybrid functional agent that directly traps alkyl radicals (R·) and decomposes peroxides to inhibit thermal oxidative degradation of polymers. Its core advantage lies in excellent processing stability, long-term thermal stability, and low color.

[0037] In some embodiments, the hydroxylamine antioxidant can be one or more of Irgastab FS-042, HP-136.

[0038] In some embodiments, the antioxidant is a combination of a hindered amine antioxidant and a hydroxylamine antioxidant. The weight ratio of the hindered phenolic and hydroxylamine antioxidant is > 1 and < 3.

[0039] In some embodiments, the weight ratio of the hindered amine and hydroxylamine antioxidant is greater than or equal to 1.5 and less than or equal to 2.5.

[0040] In some embodiments, the hindered phenolic antioxidant is a class of antioxidants that protect the phenolic hydroxyl group (-OH) from capturing free radicals by steric hindrance, interrupting the oxidative chain reaction of polymers. Its effectiveness depends on the steric hindrance effect and resonance stabilization provided by the bulky ortho substituent (usually a tert-butyl group).

[0041] In some embodiments, the hindered phenolic antioxidant is one or more of Irganox 1076, Irganox 2246, Irganox 1010, Irganox 3114.

[0042] In some embodiments, the antioxidant is a thioester antioxidant. Thioester antioxidants are important antioxidants in polymer stabilization systems, with a core structure of dialkyl thiodipropionate, which gradually oxidizes and decomposes hydroperoxides through thioether groups to inhibit the regeneration of free radical chain reactions. The polymer stabilization aid blocks the secondary generation of free radicals by efficiently decomposing hydroperoxides.

[0043] In some embodiments, the thioester antioxidant is one or more of Irganox PS 802, Irganox DSTDP, Anox DTDTP.

[0044] In some embodiments, the antioxidant is a combination of a hindered phenolic antioxidant and a thioester antioxidant. The weight ratio of the hindered phenolic antioxidant to the thioester antioxidant is greater than or equal to 1 and less than or equal to 3.

[0045] In some embodiments, the weight ratio of the hindered phenolic antioxidant to the thioester antioxidant is greater than or equal to 1.5 and less than or equal to 2.5.

[0046] In some embodiments, more than two kinds of composite antioxidants are used. The composite antioxidant is a mixture of two or more kinds of antioxidants in a certain ratio, which can exert a synergistic effect of different antioxidants and provide more comprehensive antioxidant protection.

[0047] In some embodiments, the composite antioxidant is a combination of a hindered amine antioxidant and a phosphite antioxidant, a hindered phenolic antioxidant and a hindered amine antioxidant, a phosphite antioxidant and a hindered amine antioxidant, a hindered phenolic antioxidant and a hydroxylamine antioxidant, etc.

[0048] In some embodiments, the polyolefin base layer further comprises 0.08 to 5 parts of a crosslinking aid based on 100 parts by weight of the polyolefin elastomer.

[0049] Examples of the crosslinking aid include one or more of diallylamine, diallyl sulfide, N,N-dimethyl-bisacrylamide, ethylene glycol dimethacrylate, triallyl cyanurate, triallyl isocyanurate, trimethylolpropane trimethacrylate, tetramethylolmethane tetraacrylate, glycidyl (meth)acrylate, methyl (meth)acrylate, glyceryl tripropylene acrylate, 2-carboxyethyl acrylate, isobornyl (meth)acrylate, 2-hydroxyethyl methacrylate phosphate, and tripropylene glycol triacrylate.

[0050] In some embodiments, the crosslinking aid can form crosslinks in the continuous phase of the ethylene-α-olefin copolymer or at the blending interface between the ethylene-α-olefin copolymer and the EPDM under irradiation. The amount of the crosslinking aid added can be adjusted according to actual conditions.

[0051] In some embodiments, there is an adhesive layer between the polyolefin base layer and the base surface, which is composed of an ethylene-α-olefin copolymer, a functional group grafted ethylene-α-olefin copolymer, an antioxidant, a bonding resin, and a filler.

[0052] In some embodiments, the functional group grafted ethylene-α-olefin copolymer is a maleic anhydride grafted ethylene-α-olefin copolymer.

[0053] In some embodiments, the filler is a color master batch or an inorganic compound, which can be selected by a person skilled in the art according to prior art.

[0054] In some embodiments, the auxiliary agent includes a flame retardant, which can be selected by those skilled in the art according to the prior art.

[0055] In some embodiments, the yellowing-resistant automotive interior leather has a foam layer, which can be purchased. Commonly used foam layers have a thickness of 50 microns to 500 microns and are based on PU or polyolefin.

[0056] In some embodiments, the yellowing-resistant automotive interior leather has a coating layer, which can be made of a coating material known in the art for leather, including one or more of polyurethane, acrylate, or silicone. The coating layer generally has suitable wear resistance, brightness, and adhesion, etc., which can be selected by those skilled in the art according to actual needs.

[0057] Those skilled in the art can prepare the high-hardness automotive interior leather according to the prior art and test the sample according to the following performance test method.

[0058] Example 1

[0059] The following examples more specifically describe the disclosure of the present application, which are merely illustrative and various modifications and variations are obvious to those skilled in the art within the scope of the disclosure. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by weight, and the reagents and instruments used in the examples are commercially available.

[0060] Sample preparation:

[0061] Step 1: Blending and granulation

[0062] The ethylene-alpha olefin copolymer LC675, the ethylene-propylene-diene rubber 3032PM, and the auxiliary agent were added to a twin-screw extruder (length-diameter ratio 40:1), and the temperature zones were set as follows:

[0063] Feeding section: 160°C

[0064] Melt section: 175-185°C

[0065] Die section: 165°C

[0066] Screw speed: 250 rpm

[0067] Extrusion granulation, the particles were cooled and then dried (80°C x 4h) to obtain the polyolefin elastomer master batch.

[0068] Step 2: Forming of the polyolefin substrate layer

[0069] The master batch was added to a single-screw extruder and extruded into a film (thickness 0.5 mm) through a T-shaped die, with the temperature set to 160-175°C.

[0070] Crosslinking reaction is initiated by electron beam irradiation, and the irradiation dose is determined by the desired crosslinking degree and the amount of the crosslinking aid. Step 3: Preparation of the adhesive layer (as required by the example)

[0071] Adhesive layer formula:

[0072] The ethylene-α-olefin copolymer, the maleic anhydride grafted ethylene-α-olefin copolymer (grafting rate 1.5%), the antioxidant, and the adhesive resin are mixed and melted, and then extruded into a film, which is attached between the polyolefin substrate layer and the base fabric layer.

[0073] Step 5: Laminating and post-processing

[0074] The base fabric layer, the adhesive layer (as included in the example), the foam layer (as included in the example), and the polyolefin substrate layer are combined by a hot-pressing process (temperature 140°C, pressure 5 MPa, time 5 min);

[0075] The free surface of the polyolefin substrate layer is coated with a coating and dried;

[0076] Embossing treatment (embossing roller temperature 120°C, pressure 3 MPa), and then cutting after cooling and setting.

[0077] Performance test:

[0078] Tensile strength and elongation at break: GB / T 1040.1-2006 "Determination of tensile properties of plastics".

[0079] Crosslinking degree: detected by the xylene extraction method in 5.5.3 of GB / T 29848-2018 "Ethylene-vinyl acetate copolymer (EVA) film for encapsulating photovoltaic modules".

[0080] Heat aging resistance grade: the sample size is 297mm×210mm, and the front surface is placed upward in a 120°C air drying oven for 168h, and then cooled to room temperature, and tested according to the method specified in GB / T 250-2008.

[0081] Light aging resistance grade: tested according to the method specified in the following standard Q / JL-J7110279.

[0082] Examples 1-10

[0083] The automotive interior leather in Examples 1-10 is a three-layer composite structure of the base fabric layer, the polyolefin substrate layer, and the coating layer. The polyolefin substrate layer includes: 70 parts of LF675 POE resin, 30 parts of 3092PM ternary ethylene-propylene rubber, 1 part of triallyl isocyanurate crosslinking aid, and the antioxidant in Table 1.

[0084] Example 11 differs from Example 10 in that an adhesive layer is added between the base fabric layer and the polyolefin substrate layer in Example 11.

[0085] Example 12 differs from Example 11 in that a foam layer is added between the polyolefin substrate layer and the adhesive layer in Example 12.

[0086] The type and amount of antioxidant in each example are shown in Table 1:

[0087] Table 1 Type and amount of antioxidant in Examples 1-10

[0088]

[0089]

[0090] Comparative Examples 1-4

[0091] Comparative Examples 1-4 differ from Example 10 in that different antioxidants are used in the polyolefin substrate layer.

[0092] Comparative Example 5 differs from Example 10 in that the crosslinking coagent is 0.07 parts in the polyolefin layer.

[0093] Table 2 Test results of the yellowing resistance of the automotive interior leather tested in the examples and comparative examples

[0094]

Claims

1. A yellowing-resistant automotive interior leather comprising a polyolefin substrate layer consisting of an ethylene-alpha olefin copolymer, a terpolymer of ethylene-propylene rubber and an auxiliary agent, characterized in that, The polyolefin base layer has a cross-linking degree greater than 30%, the auxiliary agent includes an antioxidant, and the antioxidant is one or more of a hindered phenol antioxidant, a hydroxylamine antioxidant, a hindered amine antioxidant, and a thioester antioxidant.

2. The yellowing-resistant automotive interior leather according to claim 1, characterized in that, The polyolefin base layer includes 100 parts by weight of the ethylene-alpha olefin copolymer and the ethylene-propylene-diene rubber in total, wherein the ethylene-alpha olefin copolymer is 40-90 parts, the ethylene-propylene-diene rubber is 10-60 parts, and the auxiliary agent is 0.1-10 parts, wherein the antioxidant is 0.1-0.6 parts.

3. The yellowing-resistant automotive interior leather according to claim 2, characterized in that, The auxiliary agent includes 0.1-0.6 parts of an antioxidant, 0.1-0.5 parts of a coupling agent, 0.08-5 parts of a cross-linking auxiliary agent, and 0-5 parts of a polyethylene color master batch.

4. The yellowing-resistant automotive interior leather according to any one of claims 1 to 3, characterized in that The antioxidant is a hindered amine antioxidant.

5. The yellowing-resistant automotive interior leather according to any one of claims 1 to 3, characterized in that The antioxidant is a combination of the hindered amine antioxidant and the hydroxylamine antioxidant.

6. The yellowing-resistant automotive interior leather according to claim 5, characterized in that The weight ratio of the hindered amine antioxidant to the hydroxylamine antioxidant is greater than or equal to 1 and less than or equal to 3.

7. The yellowing-resistant automotive interior leather according to any one of claims 1 to 3, characterized in that The antioxidant is a hindered phenol antioxidant.

8. The yellowing-resistant automotive interior leather according to any one of claims 1 to 3, characterized in that The antioxidant is a combination of the hindered phenol antioxidant and the thioester antioxidant.

9. The yellowing-resistant automotive interior leather according to claim 8, characterized in that The weight ratio of the hindered phenol antioxidant to the thioester antioxidant is greater than or equal to 1 and less than or equal to 3.

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