EB curing coating for artificial leather

Abstract

The invention relates to the technical field of artificial leather coatings, in particular to an EB curing coating for artificial leather, which is prepared from the following raw material components in parts by weight: 35-45 parts of polyurethane acrylate prepolymer containing epoxy groups; 30 to 40 parts of a reactive diluent; 5-8 parts of modified silicon dioxide nanoparticles; and 0.5-3 parts of an auxiliary agent. The epoxy group-containing polyurethane acrylate prepolymer is introduced, the binding force between the coating and the non-woven fabric is improved through the reaction of the epoxy group and the hydroxyl / carboxyl group on the surface of the non-woven fabric, and meanwhile, the bonding force between the coating and the non-woven fabric is improved through the introduction of the silicon dioxide nanoparticles. The epoxy group tackifying end of the polyurethane acrylate prepolymer containing the epoxy group is mechanically embedded with the nanoparticles, so that the stripping force of the coating on the non-woven fabric is further improved, the stripping strength between the prepared EB curing coating and the non-woven fabric is remarkably improved, the EB curing coating is endowed with excellent adhesive force, and the coating is prevented from falling off.

Description

Technical Field

[0001] The invention relates to the technical field of artificial leather coatings, in particular to an EB curing coating for artificial leather. Background Art

[0002] As a substitute for natural leather, artificial leather is widely used in clothing, furniture, automotive interiors, and other fields. The coating properties directly affect the softness, durability, and texture of the final product. The preparation of traditional artificial leather relies on the "release paper transfer method." Its core process is: apply the imitation leather coating to the patterned release paper → bake and cure → apply the adhesive → laminate to the non-woven fabric → bake and cure to remove the solvent → peel off the release paper. The imitation leather coating and adhesive are usually solvent-based polyurethane (PU) or water-based polyurethane (WPU), but both have low peel strength and poor adhesion to low-surface-energy non-woven fabrics, and are easy to fall off. Summary of the Invention

[0003] In order to solve the problem of poor adhesion between artificial leather coating and non-woven fabric in the prior art, the present invention provides an EB-cured coating. The coating prepared by the EB-cured coating has high peel strength with the non-woven fabric, solving the problem of poor adhesion between artificial leather coating and non-woven fabric in the prior art.

[0004] The technical solution adopted by the present invention to solve its technical problem is: An EB curing coating for artificial leather, comprising the following components in parts by weight: 35-45 parts of epoxy-containing polyurethane acrylate prepolymer; 30-40 parts of active diluent; 5-8 parts of modified silica nanoparticles; 0.5-5 parts of additives.

[0005] Optionally, the epoxy-containing polyurethane acrylate prepolymer is prepared according to the following method: S1: After vacuum dehydration of thioether-modified diol and polyether diol at 50-70°C, aliphatic diisocyanate is added to react to form a polyurethane intermediate containing a thioether bond; S2: adding epoxy-terminated polyethylene glycol to the polyurethane intermediate for reaction, cooling the mixture to 30-50° C., adding hydroxyethyl acrylate for reaction, and obtaining an epoxy-containing polyurethane acrylate prepolymer.

[0006] Optionally, the thioether bond-modified diol is thiodiglycol.

[0007] Optionally, the polyether glycol is polytetramethylene ether glycol.

[0008] Optionally, the mass ratio of the thioether bond modified diol, the polyether diol, the aliphatic diisocyanate, the epoxy-terminated polyethylene glycol, and the hydroxyethyl acrylate is 1: (1.5-5): (0.75-1.5): (0.1-0.7): (0.1-0.7).

[0009] Optionally, the reactive diluent includes 1,4-butanediol diacrylate and trimethylolpropane triacrylate.

[0010] Optionally, the mass ratio of the 1,4-butanediol diacrylate to the trimethylolpropane triacrylate is (95-97): (3-5).

[0011] Optionally, the silica nanoparticles are amino-modified silica nanoparticles.

[0012] Optionally, the amino-modified silica nanoparticles are prepared by the following method: mixing a silane coupling agent with silica nanoparticles, adding a solvent, ultrasonically dispersing the mixture, and removing the solvent to obtain the amino-modified silica nanoparticles.

[0013] Optionally, the auxiliary agent is selected from at least one of a leveling agent, a defoaming agent, a light stabilizer, and a plasticizer.

[0014] The beneficial effects of the present invention are: The EB-cured coating for artificial leather provided by the present invention introduces an epoxy-containing polyurethane acrylate prepolymer, so that one end of the epoxy-containing polyurethane acrylate prepolymer becomes an epoxy-containing viscosity-enhancing end. The epoxy group reacts with hydroxyl / carboxyl groups on the surface of the non-woven fabric to improve the bonding strength between the coating and the non-woven fabric. At the same time, by introducing silica nanoparticles, the epoxy-containing viscosity-enhancing end of the epoxy-containing polyurethane acrylate prepolymer and the nanoparticles mechanically intercalate, further improving the peeling force of the coating on the non-woven fabric. The peeling strength between the prepared EB-cured coating and the non-woven fabric is significantly improved, thereby imparting excellent adhesion to the non-woven fabric and preventing the coating from falling off. DETAILED DESCRIPTION

[0015] The present invention will now be described in further detail. The embodiments described below are exemplary and intended to explain the present invention, but should not be construed as limiting the present invention. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0016] In order to solve the problem of poor adhesion between artificial leather coating and non-woven fabric in the prior art, the present invention provides an EB curing coating for artificial leather, wherein the raw materials thereof include the following components in parts by weight: epoxy-containing polyurethane acrylate prepolymer 35-45 parts; active diluent 30-40 parts; silica nanoparticles 5-8 parts; auxiliary 0.5-5 parts.

[0017] The EB curing coating for artificial leather provided by the present application introduces an epoxy-containing polyurethane acrylate prepolymer, so that one end of the epoxy group in the epoxy-containing polyurethane acrylate prepolymer becomes an epoxy group tackifying end, and the bonding force between the coating and the non-woven fabric is improved by the reaction of the epoxy group with the hydroxyl group / carboxyl group on the surface of the non-woven fabric. At the same time, by introducing silica nanoparticles, the epoxy group tackifying end of the epoxy-containing polyurethane acrylate prepolymer is mechanically embedded with the nanoparticles, further improving the peeling force of the coating on the non-woven fabric, significantly improving the peeling strength between the prepared EB curing coating and the non-woven fabric, and giving it excellent adhesion to avoid the coating from falling off.

[0018] The epoxy-containing polyurethane acrylate prepolymer of the present application is preferably prepared as follows: S1: After the thioether bond modified diol and the polyether diol are vacuum dehydrated at 50-70℃, an aliphatic diisocyanate is added to react to form a polyurethane intermediate containing a thioether bond; In the step S1, the vacuum dehydration is preferably 1 h (moisture ≤0.05%); the aliphatic diisocyanate is preferably hexamethylene diisocyanate (HDI, isocyanate index 1.05); and the reaction after adding the aliphatic diisocyanate is preferably 2 h; S2: The epoxy-terminated polyethylene glycol is added to the polyurethane intermediate to react, preferably for 1 h, the epoxy group is retained, and the temperature is lowered to 30-50℃, and then hydroxyethyl acrylate (HEA, molar ratio of hydroxyl group to acrylate 1:1) is added to react to obtain the epoxy-containing polyurethane acrylate prepolymer.

[0019] The viscosity of the prepared epoxy-containing polyurethane acrylate prepolymer is preferably 5000-8000 mPa·s at 25℃.

[0020] In this preparation process, the soft segment of the epoxy-containing polyurethane acrylate prepolymer is composed of high molecular weight polyether diol and thioether bond modified diol, which provides dynamic reversible breaking-recombination ability under mild conditions of 50~80℃, improving elasticity and self-repairing property; the hard segment is generated by the reaction of aliphatic diisocyanate and epoxy-terminated polyethylene glycol (PEG-EG), and the epoxy group acts as a "tackifying end" to participate in interfacial bonding; after the reaction of the soft segment and the hard segment, the remaining hydroxyl group reacts with hydroxyethyl acrylate (HEA) to introduce an acrylate double bond (-C=C-), generating a cross-linking active end as an EB curing site.

[0021] Based on this, the epoxy-containing polyurethane acrylate prepolymer prepared by the present invention becomes a double-end functional design structure, one end of which is an acrylate group (for EB cross-linking) and the other end is an epoxy group (to react with the hydroxyl / carboxyl group on the surface of the non-woven fabric), thereby ensuring the EB curing performance of the coating while improving the bonding strength between the coating and the non-woven fabric.

[0022] Although the soft segment of traditional PU coating (such as polyether diol) provides flexibility, the cross-linking density of the hard segment (diisocyanate and chain extender) is fixed, and it is prone to plastic deformation after long-term stretching. The elongation at break is usually ≤300%. When used in artificial leather, it leads to insufficient elasticity of the artificial leather. During the repeated stretching and rebound process, microcracks inside the coating are easy to expand, and the bending resistance is usually ≤50,000 times before breaking, resulting in poor fatigue resistance of the artificial leather.

[0023] Based on this, the epoxy-containing polyurethane acrylate prepolymer in the present invention is a dynamic covalent bond-double-end functional polyurethane acrylate. The soft segment in its molecular structure provides dynamic reversible fracture-recombination ability under mild thermal conditions (50-80°C) through a sulfide bond (-S-), thereby improving the elasticity and self-healing properties of the coating. The epoxy group in the hard segment acts as a "tackifying end" to participate in interfacial bonding. After the reaction of the soft segment and the hard segment, the remaining hydroxyl group reacts with hydroxyethyl acrylate (HEA) to introduce an acrylate double bond (-C=C-) as an EB curing site, making the polyurethane acrylate prepolymer a double-end functional design: one end is an acrylate group for EB cross-linking, and the other end is an epoxy group that reacts with the hydroxyl / carboxyl group on the surface of the non-woven fabric, thereby providing a high-elasticity and strong-adhesion EB-cured polyurethane resin for artificial leather. The problems of insufficient elasticity, weak adhesion, and poor fatigue resistance of traditional EB-cured polyurethane are solved by enhancing elasticity through dynamic covalent bonds, and the double-end functional prepolymer simultaneously achieves cross-linking and interfacial adhesion, as well as nano-composite interface strengthening.

[0024] In the present invention, the preferred thioether bond-modified diol is thiodiglycol, and the preferred polyether diol is polytetramethylene ether glycol (PTMG-3000, molecular weight 3000 g / mol).

[0025] The present invention preferably has an epoxy group content of (0.3-0.8) wt% in the epoxy-terminated polyethylene glycol (PEG-EG), and specifically preferably the epoxy-terminated polyethylene glycol is prepared according to the following method: (1) Dissolve polyethylene glycol (PEG, molecular weight 200-800 g / mol, purity ≥99%) in anhydrous ether and heat to 60-70°C; (2) Slowly add epichlorohydrin (ECH, purity ≥98%) and 50% sodium hydroxide solution (molar ratio PEG:ECH:NaOH = 1:2.2:0.1) dropwise, keep stirring (300 rpm) and react for 4-6 hours; (3) After cooling to room temperature, wash the organic phase with deionized water and remove the aqueous phase by separation; (4) The organic phase was dried over anhydrous magnesium sulfate, filtered, and distilled under reduced pressure to remove the solvent. The organic phase was then purified by silica gel column chromatography and vacuum dried to constant weight to obtain epoxy-terminated polyethylene glycol (PEG-EG) with an epoxy content of 0.3-0.8 wt%.

[0026] In the preparation process of the epoxy-containing polyurethane acrylate prepolymer of the present invention, the mass ratio of the thioether bond-modified diol, the polyether diol, the hexamethylene diisocyanate, the epoxy-terminated polyethylene glycol, and the hydroxyethyl acrylate is 1: (1.5-5): (0.75-1.5): (0.1-0.7): (0.1-0.7).

[0027] The preferred active diluent of the present invention is a flexible-crosslinking bifunctional monomer. Specifically, the preferred active hygroscopic agent includes 1,4-butanediol diacrylate and trimethylolpropane triacrylate, and the mass ratio of 1,4-butanediol diacrylate to trimethylolpropane triacrylate is preferably (95-97): (3-5).

[0028] In the present invention, the silica nanoparticles are preferably modified silica nanoparticles. Specifically, the modified silica nanoparticles are preferably amino-modified silica nanoparticles, so that the modified silica nanoparticles become nanocomposite thickeners, further increasing the bonding strength between the coating and the non-woven fabric.

[0029] The amino-modified silica nanoparticles of the present invention are preferably prepared by the following method: mixing a silane coupling agent with silica nanoparticles, adding a solvent, ultrasonically dispersing, and removing the solvent to obtain modified silica nanoparticles.

[0030] Specifically, in the preparation process of amino-modified silica nanoparticles, the silane coupling agent is γ-aminopropyltriethoxysilane KH-550, the particle size of the silica nanoparticles is 50-100 nm, the mass ratio of the silane coupling agent to the silica nanoparticles is 1:20, and the solvent is ethanol.

[0031] In the present invention, the additive in the EB-curing coating for artificial leather is preferably selected from at least one of a leveling agent, a defoaming agent, a light stabilizer, and a plasticizer, and further preferably, the leveling agent is BYK-333, the defoaming agent is BYK-088, the light stabilizer is Tinuvin 770, and the plasticizer is epoxidized soybean oil ESO.

[0032] The EB curing coating for artificial leather provided by the present invention can be prepared according to the following method: According to the formula, an epoxy-containing polyurethane acrylate prepolymer, a reactive diluent, silica nanoparticles, and an additive were added to a high-speed mixer and stirred at 1000 rpm for 15 minutes until the mixture was uniform and free of particles, thereby obtaining an EB-cured polyurethane resin composition, i.e., an EB-cured coating for artificial leather.

[0033] When the EB curing coating provided by the present invention is used for artificial leather, the following process can be used: 1) Non-woven fabric pretreatment: If the material is PP, use plasma treatment (power 50 W, time 30 s) to make its surface energy ≥40 mN / m; 2) Coating preparation: Apply the EB-cured coating evenly to the pre-treated non-woven fabric surface with a coating thickness of 80-120 μm; 3) EB curing: Use an electron accelerator (energy 100 keV, dose 80 kGy) to cure the coating to ensure that the acrylate double bond conversion rate is ≥92%.

[0034] Traditional UV curing requires the addition of photoinitiators and has a limited penetration depth (≤0.1 mm). Electron beam (EB) curing has become an emerging technology to replace UV curing because it does not require photoinitiators, has a fast curing speed (seconds), and a large penetration depth (up to several millimeters). However, traditional PU structures have low reactivity with EB free radicals, and the double bond conversion rate is less than 80%, resulting in high internal stress and easy cracking in the coating. Especially in the field of artificial leather, there is no technical solution that simultaneously meets the requirements of high elasticity, strong adhesion and fatigue resistance, which limits the application of EB-cured coatings in the artificial leather field.

[0035] Based on this, the EB-cured coating for artificial leather provided by the present invention, compared with the prior art, has excellent fatigue resistance due to the dynamic fracture-recombination characteristics of the thioether bonds in the soft segment, with an elongation at break ≥400% and a bending resistance ≥200,000 times, so that the prepared artificial leather has excellent high elasticity; the epoxy group viscosity-increasing end mechanically intercalates with the nanoparticles, and the peel strength of the PP non-woven fabric is ≥6 N / cm, far exceeding the traditional PU system, giving the coating excellent adhesion; the EB curing double bond conversion rate is ≥92%, and the curing time is only 2 minutes (traditional UV requires 30 seconds but has shallow penetration), which improves production efficiency and can achieve efficient curing; the introduction of hindered amine light stabilizers inhibits free radical oxidative degradation, and the ΔE is ≤3 after 500 hours of xenon lamp aging, so that the prepared artificial leather has excellent weather resistance; the plasticizer and the flexible diluent work together to ensure that the prepared artificial leather remains flexible and free of brittle cracks at -20°C.

[0036] In summary, this invention provides a highly elastic and highly adhesive EB-cured polyurethane resin for artificial leather. Dynamic covalent bonds (thioether bonds) enhance the elasticity of the soft segment. A dual-end functional prepolymer (acrylate end + epoxy tackifier end) simultaneously achieves crosslinking and interfacial bonding. Combined with a nanocomposite tackifier for enhanced mechanical intercalation, this resin overcomes the issues of insufficient elasticity and weak adhesion associated with traditional EB-cured polyurethanes. This resin coating exhibits an elongation at break of ≥400%, a peel strength of ≥6 N / cm against PP nonwovens, and a flex resistance of ≥200,000 cycles. It is suitable for artificial leather production, enhancing product durability and quality.

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below.

[0038] Unless otherwise specified, the raw material information in each embodiment and comparative example of the present invention is as follows: Polytetramethylene ether glycol PTMG is PTMG-3000 (molecular weight 3000 g / mol, a BASF product); thiodiglycol has a molecular weight of 122 g / mol and is a product of Aladdin; hexamethylene diisocyanate HDI is industrial grade and is a Wanhua Chemical product; hydroxyethyl acrylate HEA is industrial grade and is a Changxing Materials product; 1,4-butanediol diacrylate BDDA is industrial grade and is a Sartomer product; and trimethylolpropane triacrylate TMPTA is industrial grade and is a Sartomer product.

[0039] The epoxy-terminated polyethylene glycol (PEG-EG) in each embodiment of the present invention and the comparative example was prepared according to the following method: (1) Dissolve polyethylene glycol in anhydrous ether and heat to 60-70°C; (2) Slowly add epichlorohydrin (ECH, purity ≥98%) and 50% sodium hydroxide solution (molar ratio PEG:ECH:NaOH = 1:2.2:0.1) dropwise, keep stirring (300 rpm) and react for 5 h; (3) After cooling to room temperature, wash the organic phase with deionized water and remove the aqueous phase by separation; (4) The organic phase was dried over anhydrous magnesium sulfate, filtered, and distilled under reduced pressure to remove the solvent. The organic phase was then purified by silica gel column chromatography and dried under vacuum to constant weight to obtain epoxy-terminated polyethylene glycol (PEG-EG) with an epoxy content of 0.5 wt%.

[0040] The EB curing coatings in the various embodiments of the present invention and the comparative examples were prepared according to the following method: According to the formula amount, each component was added into a high-speed mixer and stirred at 1000 rpm for 15 minutes until it was uniform and free of particles, thereby obtaining an EB-cured polyurethane resin composition, namely, an EB-cured coating for artificial leather.

[0041] Example 1 This embodiment provides an EB curing coating for artificial leather, and its raw materials include the following components in parts by weight: 40 parts of epoxy-containing polyurethane acrylate prepolymer; 35 parts of active diluent; 6 parts of silicon dioxide nanoparticles; BYK-333 0.5 parts; BYK-088 0.3 parts; Tinuvin 770 0.2 parts; ESO 3 copies.

[0042] The epoxy-containing polyurethane acrylate prepolymer is prepared as follows: S1: Add thiodiglycol and polytetramethylene ether glycol (PTMG) into a reactor, heat to 60°C, vacuum dehydrate for 1 hour, add hexamethylene diisocyanate (HDI) (isocyanate index 1.05), and react at 60°C for 2 hours (infrared detection - NCO content ≤ 0.5%) to generate a polyurethane intermediate containing a thioether bond; S2: PEG-EG was added to the reactor and the reaction continued for 1 h. The temperature was then lowered to 40°C, and HEA was added and the reaction continued for 0.5 h to obtain an epoxy-containing polyurethane acrylate prepolymer. The viscosity of the prepolymer was 6500 mPa·s at 25°C as measured by a rotational viscometer. The mass ratio of thiodiglycol, polytetramethylene ether glycol PTMG, hexamethylene diisocyanate HDI, PEG-EG and HEA is 1:3:1.28:0.4:0.48.

[0043] The active diluent was prepared as follows: 1,4-Butanediol diacrylate BDDA and trimethylolpropane triacrylate TMPTA were mixed in a mass ratio of 95:5 and stirred evenly (speed 300 rpm, 5 min) to obtain a flexible-crosslinking bifunctional diluent, i.e., a reactive diluent.

[0044] Silica nanoparticles were prepared as follows: KH-550 was mixed with silica nanoparticles, ethanol was added, ultrasonically dispersed for 30 min, and filtered and dried to obtain amino-modified silica nanoparticles; the particle size of the silica nanoparticles was 80 nm, the mass ratio of KH-550 to silica nanoparticles was 1:20, and the dosage ratio of KH-550 to ethanol was 1 g:10 mL.

[0045] Example 2 This embodiment provides an EB curing coating for artificial leather, and its raw materials include the following components in parts by weight: 35 parts of epoxy-containing polyurethane acrylate prepolymer; 40 parts of active diluent; 8 parts of silicon dioxide nanoparticles; BYK-333 0.5 parts; BYK-088 0.3 parts; Tinuvin 770 0.2 parts; ESO 3 copies.

[0046] The preparation methods of the epoxy-containing polyurethane acrylate prepolymer, the active diluent, and the silicon dioxide nanoparticles are the same as those in Example 1.

[0047] Example 3 This embodiment provides an EB curing coating for artificial leather, and its raw materials include the following components in parts by weight: 45 parts of epoxy-containing polyurethane acrylate prepolymer; 30 parts of active diluent; 5 parts of silicon dioxide nanoparticles; BYK-333 0.5 parts; BYK-088 0.3 parts; Tinuvin 770 0.2 parts; ESO 3 copies.

[0048] The preparation methods of the epoxy-containing polyurethane acrylate prepolymer, the active diluent, and the silicon dioxide nanoparticles are the same as those in Example 1.

[0049] Example 4 This embodiment provides an EB curing coating for artificial leather, and its raw materials include the following components in parts by weight: 40 parts of epoxy-containing polyurethane acrylate prepolymer; 35 parts of active diluent; 6 parts of silicon dioxide nanoparticles; BYK-333 0.5 parts; BYK-088 0.3 parts; Tinuvin 770 0.2 parts; ESO 3 copies.

[0050] The epoxy-containing polyurethane acrylate prepolymer is prepared as follows: S1: Add thiodiglycol and polytetramethylene ether glycol (PTMG) into a reactor, heat to 60°C, vacuum dehydrate for 1 hour, add hexamethylene diisocyanate (HDI) (isocyanate index 1.05), and react at 60°C for 2 hours (infrared detection - NCO content ≤ 0.5%) to generate a polyurethane intermediate containing a thioether bond; S2: PEG-EG was added to the reactor and the reaction continued for 1 h. The temperature was then lowered to 40°C, and HEA was added and the reaction continued for 0.5 h to obtain an epoxy-containing polyurethane acrylate prepolymer. The viscosity of the prepolymer was 7200 mPa·s at 25°C as measured by a rotational viscometer. The mass ratio of thiodiglycol, polytetramethylene ether glycol PTMG, hexamethylene diisocyanate HDI, PEG-EG and HEA is 1:1.5:0.75:0.3:0.275.

[0051] The active diluent was prepared as follows: 1,4-Butanediol diacrylate BDDA and trimethylolpropane triacrylate TMPTA were mixed in a mass ratio of 97:3 and stirred evenly (speed 300 rpm, 5 min) to obtain a flexible-crosslinking bifunctional diluent, i.e., a reactive diluent.

[0052] Silica nanoparticles were prepared as follows: KH-550 was mixed with silica nanoparticles, ethanol was added, ultrasonically dispersed for 30 min, and filtered and dried to obtain amino-modified silica nanoparticles; the particle size of the silica nanoparticles was 80 nm, the mass ratio of KH-550 to silica nanoparticles was 1:20, and the dosage ratio of KH-550 to ethanol was 1 g:10 mL.

[0053] Comparative Example 1 This comparative example provides an EB curing coating for artificial leather, and its raw materials include the following components in parts by weight: 40 parts of polyurethane acrylate prepolymer; 35 parts of active diluent; 6 parts of silicon dioxide nanoparticles; BYK-333 0.5 parts; BYK-088 0.3 parts; Tinuvin 770 0.2 parts; ESO 3 copies.

[0054] Wherein, the polyurethane acrylate prepolymer is prepared according to the following method: S1: Add thiodiglycol and polytetramethylene ether glycol (PTMG) into a reactor, heat to 60°C, vacuum dehydrate for 1 hour, add hexamethylene diisocyanate (HDI) (isocyanate index 1.05), and react at 60°C for 2 hours (infrared detection - NCO content ≤ 0.5%) to generate a polyurethane intermediate containing a thioether bond; S2: Cool the mixture to 40°C, add HEA to the reactor, and react for 0.5 h to obtain a polyurethane acrylate prepolymer. The viscosity of the prepolymer is 3500 mPa·s at 25°C as measured by a rotational viscometer. The mass ratio of thiodiglycol, polytetramethylene ether glycol PTMG, hexamethylene diisocyanate HDI, and HEA is 1:3:1.28:0.48.

[0055] The active diluent was prepared as follows: 1,4-Butanediol diacrylate BDDA and trimethylolpropane triacrylate TMPTA were mixed in a mass ratio of 95:5 and stirred evenly (speed 300 rpm, 5 min) to obtain a flexible-crosslinking bifunctional diluent, i.e., a reactive diluent.

[0056] Silica nanoparticles were prepared as follows: KH-550 was mixed with silica nanoparticles, ethanol was added, ultrasonically dispersed for 30 min, and filtered and dried to obtain amino-modified silica nanoparticles; the particle size of the silica nanoparticles was 80 nm, the mass ratio of KH-550 to silica nanoparticles was 1:20, and the dosage ratio of KH-550 to ethanol was 1 g:10 mL.

[0057] Comparative Example 2 This comparative example provides an EB curing coating for artificial leather, and its raw materials include the following components in parts by weight: 40 parts of polyurethane acrylate prepolymer; 35 parts of active diluent; 6 parts of silicon dioxide nanoparticles; BYK-333 0.5 parts; BYK-088 0.3 parts; Tinuvin 770 0.2 parts; ESO 3 copies.

[0058] Wherein, the polyurethane acrylate prepolymer is prepared according to the following method: S1: Add polytetramethylene ether glycol (PTMG) to a reactor, heat to 60°C, vacuum dehydrate for 1 h, add hexamethylene diisocyanate (HDI) (isocyanate index 1.05), and react at 60°C for 2 h (infrared detection: NCO content ≤ 0.5%) to generate a polyurethane intermediate. S2: PEG-EG was added to the reactor and the reaction continued for 1 h. The temperature was then lowered to 40°C, and HEA was added and the reaction continued for 0.5 h to obtain an epoxy-containing polyurethane acrylate prepolymer. The viscosity of the prepolymer was 5200 mPa·s at 25°C as measured by a rotational viscometer. The mass ratio of polytetramethylene ether glycol PTMG, hexamethylene diisocyanate HDI, PEG-EG and HEA is 3:1.28:0.4:0.48.

[0059] The active diluent was prepared as follows: 1,4-Butanediol diacrylate BDDA and trimethylolpropane triacrylate TMPTA were mixed in a mass ratio of 95:5 and stirred evenly (speed 300 rpm, 5 min) to obtain a flexible-crosslinking bifunctional diluent, i.e., a reactive diluent.

[0060] Silica nanoparticles were prepared as follows: KH-550 was mixed with silica nanoparticles, ethanol was added, ultrasonically dispersed for 30 min, and filtered and dried to obtain amino-modified silica nanoparticles; the particle size of the silica nanoparticles was 80 nm, the mass ratio of KH-550 to silica nanoparticles was 1:20, and the dosage ratio of KH-550 to ethanol was 1 g:10 mL.

[0061] The active diluent was prepared as follows: 1,4-Butanediol diacrylate BDDA and trimethylolpropane triacrylate TMPTA were mixed in a mass ratio of 95:5 and stirred evenly (speed 300 rpm, 5 min) to obtain a flexible-crosslinking bifunctional diluent, i.e., a reactive diluent.

[0062] Silica nanoparticles were prepared as follows: KH-550 was mixed with silica nanoparticles, ethanol was added, ultrasonically dispersed for 30 min, and filtered and dried to obtain amino-modified silica nanoparticles; the particle size of the silica nanoparticles was 80 nm, the mass ratio of KH-550 to silica nanoparticles was 1:20, and the dosage ratio of KH-550 to ethanol was 1 g:10 mL.

[0063] Comparative Example 3 This comparative example provides an EB curing coating for artificial leather, and its raw materials include the following components in parts by weight: 40 parts of epoxy-containing polyurethane acrylate prepolymer; 35 parts of active diluent; BYK-333 0.5 parts; BYK-088 0.3 parts; Tinuvin 770 0.2 parts; ESO 3 copies.

[0064] The epoxy-containing polyurethane acrylate prepolymer is prepared as follows: S1: Add thiodiglycol and polytetramethylene ether glycol (PTMG) into a reactor, heat to 60°C, vacuum dehydrate for 1 hour, add hexamethylene diisocyanate (HDI) (isocyanate index 1.05), and react at 60°C for 2 hours (infrared detection - NCO content ≤ 0.5%) to generate a polyurethane intermediate containing a thioether bond; S2: PEG-EG was added to the reactor and the reaction continued for 1 h. The temperature was then lowered to 40°C, and HEA was added and the reaction continued for 0.5 h to obtain an epoxy-containing polyurethane acrylate prepolymer. The viscosity of the prepolymer was 6500 mPa·s at 25°C as measured by a rotational viscometer. The mass ratio of 4,4'-dimethyl dithiobenzoate diol, polytetramethylene ether glycol PTMG, hexamethylene diisocyanate HDI, PEG-EG and HEA is 1:3:1.28:0.4:0.48.

[0065] The active diluent was prepared as follows: 1,4-Butanediol diacrylate BDDA and trimethylolpropane triacrylate TMPTA were mixed in a mass ratio of 95:5 and stirred evenly (speed 300 rpm, 5 min) to obtain a flexible-crosslinking bifunctional diluent, i.e., a reactive diluent.

[0066] Artificial leather was prepared using the EB-cured coatings prepared in the above examples and comparative examples according to the following method: (1) PP non-woven fabric was selected and pre-treated with plasma treatment (power 50 W, time 30 s) to make its surface energy ≥40 mN / m; (2) The EB curing coating was evenly applied to the pretreated non-woven fabric surface with a coating thickness of 100 μm; (3) The coating was cured using an electron accelerator (energy 100 keV, dose 80 kGy), and infrared detection was performed to ensure that the conversion rate of acrylate double bonds was ≥92%, thereby obtaining artificial leather.

[0067] The properties of the prepared artificial leather were tested as follows: Peel force: electronic peel tester, standard: GB3903.3-2008; Elongation at break: Electronic universal testing machine, standard: GB / T528-2009.

[0068] The test results are shown in Table 1: Table 1 Peel force (N / m) Elongation at break (%) Example 1 720 480 Example 2 700 465 Example 3 750 500 Example 4 680 470 Comparative Example 1 450 320 Comparative Example 2 580 410 Comparative Example 3 610 450 As can be seen from the data in the above table, the EB curing coating provided by the present invention, when used for artificial leather, imparts the material with excellent high elasticity, strong adhesion and fatigue resistance.

[0069] The difference between Comparative Example 1 and Example 1 is that epoxy-terminated polyethylene glycol is not added during the preparation of the polyurethane acrylate prepolymer. Due to the decrease in interfacial bonding strength and the lack of the PEG-EG hydrogen bond network, the peeling force and fatigue resistance of the coating are reduced.

[0070] The difference between Comparative Example 2 and Example 1 is that no thioether bond-modified diol is added during the preparation of the polyurethane acrylate prepolymer. Due to the lack of dynamic covalent thioether bonds, the elasticity of the coating is significantly reduced, and the fatigue resistance is reduced due to the accelerated microcrack expansion rate.

[0071] The difference between Comparative Example 3 and Example 1 is that no silica nanoparticles are added to the raw materials. Due to the lack of nanoparticle reinforcement phase, the coating network strength is weakened and the fatigue resistance is reduced (cracks are easy to propagate). At the same time, the lack of physical intercalation of nanoparticles causes the elongation at break to drop slightly to 450%.

[0072] With the above-described preferred embodiments of the present invention as inspiration, and with reference to the above description, relevant personnel are fully capable of making various changes and modifications without departing from the technical scope of this invention. The technical scope of this invention is not limited to the contents of the specification and must be determined according to the scope of the claims.

Claims

1. An EB curing coating for artificial leather, characterized in that, The raw materials include the following components in parts by weight: 35-45 parts of epoxy-containing polyurethane acrylate prepolymer; 30-40 parts of active diluent; 5-8 parts of silicon dioxide nanoparticles; 0.5-5 parts of additives.

2. The EB curing coating for artificial leather as claimed in claim 1, wherein The epoxy-containing polyurethane acrylate prepolymer is prepared according to the following method: S1: After vacuum dehydration of thioether-modified diol and polyether diol at 50-70°C, aliphatic diisocyanate is added to react to form a polyurethane intermediate containing a thioether bond; S2: adding epoxy-terminated polyethylene glycol to the polyurethane intermediate for reaction, cooling the mixture to 30-50° C., adding hydroxyethyl acrylate for reaction, and obtaining an epoxy-containing polyurethane acrylate prepolymer.

3. The EB curing coating for artificial leather as claimed in claim 2, wherein The thioether bond modified diol is thiodiglycol.

4. The EB curing coating for artificial leather as claimed in claim 2, wherein The polyether glycol is polytetramethylene ether glycol.

5. The EB curing coating for artificial leather as claimed in claim 2, wherein The mass ratio of the thioether bond modified diol, the polyether diol, the aliphatic diisocyanate, the epoxy-terminated polyethylene glycol, and the hydroxyethyl acrylate is 1: (1.5-5): (0.75-1.5): (0.1-0.7): (0.1-0.7).

6. The EB curing coating for artificial leather according to any one of claims 1 to 5, wherein The reactive diluent includes 1,4-butanediol diacrylate and trimethylolpropane triacrylate.

7. The EB curing coating for artificial leather as claimed in claim 6, wherein The mass ratio of the 1,4-butanediol diacrylate to the trimethylolpropane triacrylate is (95-97):(3-5).

8. The EB curing coating for artificial leather according to any one of claims 1 to 5, wherein The silicon dioxide nanoparticles are amino-modified silicon dioxide nanoparticles.

9. The EB curing coating for artificial leather as claimed in claim 8, wherein The amino-modified silica nanoparticles are prepared according to the following method: a silane coupling agent is mixed with silica nanoparticles, a solvent is added, ultrasonic dispersion is performed, and the amino-modified silica nanoparticles are obtained after removing the solvent.

10. The EB curing coating for artificial leather according to any one of claims 1 to 5, wherein The auxiliary agent is selected from at least one of a leveling agent, a defoaming agent, a light stabilizer, and a plasticizer.