Process for manufacturing artificial sheepskin from a silicone-coated two-layer sheepskin

Abstract

The application provides a process method for manufacturing simulated sheepskin by coating two-layer sheepskin with organic silicon, and the simulated sheepskin is composed of a surface layer, an intermediate layer, an adhesive layer and two-layer sheepskin, and the thickness ranges from 50 to 300 microns; the surface layer liquid silicone rubber contains branched chain slip agent; the intermediate layer is liquid silicone rubber with an elastic modulus lower than 2 Mpa; the adhesive layer liquid silicone rubber contains platinum catalyst with complex ligand, which can eliminate the interference of elements such as N and S in the protein of two-layer sheepskin and improve the adhesion; the simulated sheepskin of the application adopts a solvent-free coating process, and the equipment is simple and has good environmental protection; the simulated sheepskin prepared has soft hand feeling, good resilience and good slipperiness, and has good simulation effect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of leather composite materials, and particularly relates to a process for manufacturing simulated sheepskin by coating two-layer sheepskin with silicone. BACKGROUND

[0002] After a piece of sheepskin is split into layers, the top layer is removed to make high-end garment leather, and the remaining split layer can be split into multiple two-layer sheepskins, which generally have low market value. The existing processing method is usually to paste two-layer sheepskin with solvent-based PU through dry process technology, or to composite the prepared PU leather and two-layer sheepskin through adhesive lining or adhesive. The composite leather made in this way has a thick and hard feel and is not soft, and has a strong rubbery feel. Two-layer sheepskin is usually coated with dry solvent-based PU leather or water-based PU, which has the disadvantages of poor resilience, difficulty in restoring after deformation, poor resistance to high and low temperatures, and environmental pollution after long-term wear. The product made by coating dry solvent-based PU leather and pasting two-layer sheepskin is usually made by using a large amount of solvent such as DMF, which has a high boiling point and inevitably remains in the synthetic leather. Water-based PU leather usually contains 5% or more of ketone solvents or NMP organic solvents, which pollutes and risks the production environment and even the water environment. PU macromolecules are composed of a large number of urethane bonds, have high surface energy, and have poor anti-graffiti performance such as resistance to ink and marker. The long-chain macromolecules of PU are usually composed of hard and soft segments, and in addition to van der Waals forces and other intermolecular forces between the molecular chains, there is a lack of intermolecular chemical cross-linking. Although it has good mechanical properties, the molecular chains are prone to slip after being subjected to external force, and it is difficult to make an elastomer coating with low modulus and good resilience.

[0003] The silicone coating is coated with solvent-free addition-type liquid silicone, which is safe, environmentally friendly and non-polluting. The silicone coating is composed of a large number of freely rotating Si-CH3 groups, has low surface energy, and is not easy to attach low-surface-energy stains such as oil stains and ink on the surface, and is easy to wipe off. The silicone coating has good stain resistance, is easy to clean and maintain, has good air and moisture permeability, and can withstand high and low temperatures, aging, degradation and good biocompatibility. Due to the activity of the siloxane macromolecular chain and the open structure of the dimethyl group, the surface is easy to adhere, and the friction coefficient is usually large. The friction coefficient of liquid silicone is usually high, and it is difficult to make a simulated sheepskin with a dry and smooth, soft feel. Two-layer sheepskin protein usually contains elements such as N and S, which have lone pair electrons that are easy to combine with the d-orbital electrons of platinum metal to form strong adsorption bonds, which easily poisons the platinum catalyst, causes poor curing of the silicone rubber, and causes problems such as a decrease in adhesion, delamination, and sticking.

[0004] Therefore, there is an urgent need to find an environmentally friendly solvent-free liquid silicone rubber with low friction coefficient to prepare a simulated sheepskin with a dry surface, soft feel, high adhesion strength and excellent resilience. SUMMARY

[0005] To solve the problems in the prior art, the application provides a process method for manufacturing simulated sheepskin by coating two-layer sheepskin with organic silicon, wherein a branched organic silicon resin is added into a two-component addition type liquid silicon rubber as a slip agent to prepare a surface layer with a low friction coefficient; a middle layer is prepared by using a liquid silicon rubber with a low elastic modulus to provide good resilience; and a liquid silicon rubber containing a platinum catalyst with a complex ligand in the adhesive layer can eliminate the interference of elements such as N and S in the two-layer sheepskin and improve the bonding force; a solvent-free coating process is used, the equipment is simple, and the environmental protection performance is good; and the simulated sheepskin prepared has a soft hand feeling, good resilience, excellent slipperiness and good simulation effect.

[0006] In one aspect, the application provides a simulated sheepskin, which comprises, from top to bottom, a surface layer, a middle layer, an adhesive layer and two-layer sheepskin, wherein the surface layer is made of surface layer liquid silicon rubber, the surface layer liquid silicon rubber contains a branched resin slip agent, and the branched resin slip agent has a structural formula as shown in Formula I:

[0007] R 1 a R 2 b R c 3 (SiO 1 / 2 ) x (SiO 2 / 2 ) y (SiO 4 / 2 ) z

[0008] wherein R 1 is any one or several of an alkyl group with 1-8 carbon atoms, an aryl group, a cyclohexyl group and the like, R 2 is any one or several of a moisture self-crosslinking group such as a methoxy group, an ethoxy group, an acyloxy group, a silicon hydroxyl group, a silicon group trimethoxy group, a silicon group triethoxy group, a silicon group triacetyloxy methyl group, a silicon group dimethoxy group, a methyl silicon group diethoxy group, a methyl silicon group diacetyloxy group and the like. R 3 is any one or several of a bridging group of R1, R2 and Si atoms such as -CH2O-, -CH2CH2-, -CH2CH2O-, -CH2CH2CH2-, -CH2CH2CH2O-, -CH2C(=O)O-, -CH2CH2C(=O)O- and the like.

[0009] wherein (a+b) / (x+y+z)≥0.8, preferably 1≤(a+b) / (x+y+z)≤3.

[0010] x / (y+z)≥0.5, preferably 0.7≤x / (y+z)≤2.

[0011] c / (a+b) < 0.5, preferably 0.1 < c / (a+b) < 0.4

[0012] Formula I

[0013] The surface layer is a high-performance silicone surface layer using a low-friction coefficient liquid silicone rubber. In order to improve the simulation of the silicone composite two-layer sheepskin product, it is best to use but not limited to coating on the sheepskin pattern release paper, and especially to coat on the bright surface type sheepskin pattern release paper, which still has the characteristics of dryness and low friction coefficient. The coating thickness of the high-performance silicone surface layer is in the range of 5-100 microns, preferably 15-70 microns. Below this coating thickness, it is not resistant to scratching and wear. Above this coating thickness, the hand feeling is hard, the simulation is low, and the wearing comfort is poor.

[0014] On the other hand, the simulation sheepskin provided by the present application further comprises an intermediate layer between the surface layer and the adhesive layer, and the modulus of the intermediate layer is less than 2 MPa, preferably 0.5 MPa-1 MPa.

[0015] Further, the intermediate layer uses but is not limited to foamed silicone or low modulus high strength liquid silicone rubber.

[0016] Further, the adhesive layer is a low modulus adhesive layer, and the low modulus adhesive layer uses adhesive materials that can be combined with the silicone coating and the two-layer sheepskin, including but not limited to liquid silicone adhesive, silicone hot melt adhesive, moisture curing silicone modified PUR, etc. Preferably, addition type liquid silicone adhesive.

[0017] On the other hand, the present application provides a method for preparing a simulation sheepskin, comprising the following steps:

[0018] (1) coating the surface layer liquid silicone rubber on the release paper and baking to surface dryness;

[0019] (2) coating the intermediate layer liquid silicone rubber on the surface layer and baking to surface dryness;

[0020] (3) coating the adhesive layer liquid silicone rubber on the intermediate layer;

[0021] (4) laminating the adhesive layer with the two-layer sheepskin, heating and vulcanizing, peeling off from the release paper, and winding;

[0022] Or

[0023] (1) coating the surface layer liquid silicone rubber on the release paper and baking to surface dryness;

[0024] (2) coating the adhesive layer liquid silicone rubber on the surface layer;

[0025] (3) laminating the adhesive layer with the two-layer sheepskin, heating and vulcanizing, peeling off from the release paper, and winding.

[0026] Further, the surface layer liquid silicone rubber contains a branched resin slip agent, and the branched resin slip agent has a structural formula as shown in Formula I.

[0027] R 1 a R 2 b R c 3 (SiO 1 / 2 ) x (SiO 2 / 2 ) y (SiO 4 / 2 ) z

[0028] wherein R 1 is any one or several of an alkyl group with 1-8 carbon atoms, an aryl group, a cyclohexyl group, etc., R 2 is any one or several of a moisture self-crosslinking group such as a methoxy group, an ethoxy group, an acyloxy group, a silanol group, a silyltrimethoxy group, a silyltriethoxy group, a silyltriacetyloxymethyl group, a silyldimethoxy group, a methylsilyldiethoxy group, a methylsilyldiacetyloxy group, etc. 3 is any one or several of a bridging group of R1, R2, and Si atoms such as -CH2O-, -CH2CH2-, -CH2CH2O-, -CH2CH2CH2-, -CH2CH2CH2O-, -CH2C(=O)O-, -CH2CH2C(=O)O-, etc.

[0029] wherein (a+b) / (x+y+z)≥0.8, preferably 1≤(a+b) / (x+y+z)≤3.

[0030] x / (y+z)≥0.5, preferably 0.7≤x / (y+z)≤2.

[0031] c / (a+b)≤0.5, preferably 0.1≤c / (a+b)≤0.4

[0032] Formula I

[0033] Further, the branched organic silicone resin slip agent in the surface layer liquid silicone rubber has a content of 3-8%.

[0034] In some modes, the branched organic silicone resin slip agent is prepared by adding a hydrogen-containing MDQ resin and an allyl monomer, a vinyl silane coupling agent into a three-necked flask, heating to a certain temperature, adding a platinum gold complex catalyst, and reacting until no silicon hydrogen bond remains, and then cooling and discharging.

[0035] In some modes, the branched resin slip agent used in the present application includes a branched siloxane compound with active alkoxy groups, active hydroxyl groups, and the like reactive groups.

[0036] In some embodiments, the branched resin slip agent used in the present application is preferably a self-crosslinking MDQ silicone resin with alkoxy functional groups.

[0037] Further, the SiH / SiVi ratio in the topcoat liquid silicone rubber is preferably 1:1 to 2:1, preferably 1.2:1 to 1.7:1.

[0038] Further, the adhesive layer liquid silicone rubber contains a novel anti-poisoning catalyst, the ligand complex platinum catalyst, the ligand is any one or more of the following: polyphenyl phosphine ligand, hindered amine ligand, carbene ligand, modified vinyl siloxane ligand.

[0039] The novel anti-poisoning catalyst solves the defects of poor curing of silicone adhesive layer and two-layer sheepskin composite, and the decrease of adhesion. The two-layer sheepskin is composed of various proteins, containing elements such as N and S, which have lone pair electrons that are easy to combine with the d orbital electrons of platinum metal, forming a strong adsorption bond to poison the platinum catalyst, making the silicone glue curing poorly, causing the adhesion to decrease, and bringing about problems such as delamination, peeling, and stickiness. The present application uses a novel catalyst ligand complex platinum catalyst, which has stronger electron-donating ability than the conventional divinyltetramethyltetraphenyl disiloxane ligand, is less likely to produce platinum colloid and by-products during the reaction, has faster catalytic speed, and has more perfect curing degree. At the same time, this kind of ligand has larger steric hindrance and is less likely to be disturbed by electron-donating elements such as N and S.

[0040] In some embodiments, the present application uses a novel catalyst ligand, preferably a modified carbene ligand, a modified vinyl siloxane ligand, and the like, which has better stability.

[0041] Further, the preparation method of the carbene ligand complex platinum catalyst is as follows: in a reaction device, add chloroplatinic acid, isopropyl alcohol, divinyltetramethyltetraphenyl disiloxane, isopropoxy aluminum and N-heterocyclic imidazole salt, add sodium methoxide under stirring, and stir at 65-75°C for 3h, cool, filter out the solid salt, and then use dimethylbenzene to make up the volume to obtain the product.

[0042] In some embodiments, the present application provides a carbene ligand complex platinum catalyst with a structure as shown in Formula III:

[0043]

[0044] wherein R is selected from any one or more of alkyl with 1-8 carbon atoms, aryl, cyclohexyl, cyclopentanone, SiCH3, SiCH2CH3.

[0045] Further, the coating thickness of the surface layer liquid silicone rubber is 5-100 μm, the coating thickness of the intermediate layer liquid silicone rubber is 20-200 μm, and the coating thickness of the adhesive layer liquid silicone rubber is 20-200 μm.

[0046] In summary, the present application provides a method for preparing simulated sheepskin, which has the following beneficial effects:

[0047] 1. By adding synthetic branched organic silicone slip agent to the liquid silicone rubber, participating in cross-linking reaction, self-crosslinking film formation on the surface through moisture, keeping the surface of the silicone synthetic leather dry and not greasy to the touch;

[0048] 2. By using synthetic low elastic modulus liquid silicone rubber to coat the intermediate layer or high elastic sheepskin adhesive layer as the simulated sheepskin tissue structure, including but not limited to using foamed silicone rubber coating or liquid silicone rubber with an elastic modulus lower than 2 Mpa, the simulated sheepskin prepared has good elasticity;

[0049] 3. Using a new type of anti-poisoning catalyst (carbene ligand complex platinum catalyst), the defects such as poor curing of the silicone adhesive layer and the second layer of sheepskin, and the decrease of the cohesive force due to the elements N and S contained in the protein of the second layer of sheepskin are solved;

[0050] 4. By using the solvent-free liquid silicone rubber coating process, the problems of thick and hard composite sheepskin made by dry technology, strong rubber feeling, and environmental pollution of solvent type PU leather are solved;

[0051] 5. The liquid silicone rubber of the present application adopts the cross-linking and curing mode of silicon hydrogen addition, and has chemical bonds between molecular chains, which avoids the molecular chain slipping after stretching, and greatly improves the elasticity of the existing PU coated two-layer sheepskin on the market.

[0052] 6. The modulus of the liquid silicone rubber can be adjusted by changing the cross-linking structure, and the two-layer sheepskin product coated with multi-layer organic silicone with different elastic modulus has higher simulation degree. BRIEF DESCRIPTION OF DRAWINGS

[0053] Figure 1 , the schematic diagram of the structure of each layer of the simulated sheepskin of example 6

[0054] Figure 2 , the schematic diagram of the structure of each layer of the simulated sheepskin of example 12

[0055] The application will be further described in detail in connection with the following examples. It should be noted that the following examples are intended to facilitate the understanding of the application and do not limit the application in any way. The hydrogen-containing MDQ resin and the vinyl MQ resin used in the examples are produced by the present company. The reagents, auxiliaries and platinum catalysts used in the examples are self-made or purchased by known methods unless otherwise specified, which will not be described herein.

[0056] M represents -SiO in the examples 1 / 2 CH3,D represents -Si(CH3)2O 2 / 2 Q represents SiO 4 / 2

[0057] The preparation method of the hydrogen-containing MDQ resin is as follows:

[0058] Preparation Example 1: Synthesis of hydrogen-containing MDQ resin: 0.9 mol of trichlorosilane, 0.85 mol of trimethylchlorosilane, 1.2 mol of dimethyldichlorosilane, 1.2 mol of tetrachlorosilane and 200 ml of ethanol were sequentially added into a three-necked flask, 150 g of 5% hydrochloric acid aqueous solution was added dropwise at room temperature, and the external temperature was set to 60°C for 6 hours after the dropwise addition was completed. The lower resin layer was separated in a separatory funnel and washed with distilled water for three times. The resin was continuously added into the flask, and low boiling point was removed at 130°C under vacuum to obtain colorless and transparent hydrogen-containing MDQ silicon resin. The structure of the resin was analyzed by nuclear magnetic resonance as follows:

[0059] [(CH3)3SiO 1 / 2 ]8[H(CH3)2SiO 1 / 2 ] 8.8 [(CH3)2SiO 2 / 2 ] 12.2 (SiO 4 / 2 ) 12.1

[0060] The hydrogen content was 0.30% by titration analysis.

[0061] The preparation method of the vinyl MQ resin is as follows:

[0062] Preparation Example 2: 1.5 mol of trimethylchlorosilane, 0.4 mol of dimethylvinylmonochlorosilane, 2 mol of tetrachlorosilane and 200 ml of ethanol were sequentially added into a three-necked flask, 120 g of 5% hydrochloric acid aqueous solution was added dropwise at room temperature, and the external temperature was set to 60°C for 6 hours after the dropwise addition was completed. The lower resin layer was separated in a separatory funnel and washed with distilled water for three times. The resin was continuously added into the flask, and low boiling point was removed at 130°C under vacuum to obtain colorless and transparent vinyl MQ silicon resin. The structure of the resin was analyzed by nuclear magnetic resonance as follows:

[0063] [CH2=CH(CH3)2SiO 1 / 2 ]4.7 [(CH3)3SiO 1 / 2 ] 23.6 (SiO 4 / 2 ) 32.4 The vinyl content is 2.3% by titration analysis.

[0064] Preparation of branched resin slip agent of Example 1

[0065] The preparation of branched resin slip agent provided in this example includes the following steps: 0.2 mol of hydrogen-containing MDQ resin obtained in Preparation Example 1, and 0.9 mol of allyl cyclohexane, 1.6 mol of methyl vinyl diethoxysilane are put into a three-necked flask, the temperature is raised to 85°C, 30 ppm of chloroplatinic acid-isopropanol catalyst is added, and the reaction is carried out until there is no residual hydrogen, low boiling point is removed by vacuum extraction at 150°C, and the product is discharged after cooling.

[0066] The structure of the prepared branched resin slip agent is as follows:

[0067] [R1(CH2)3-Si(CH3)2O 1 / 2 ]3[R2 CH2CH2-Si(CH3)2O 1 / 2 ] 5.8 [(CH3)3SiO 1 / 2 ]8[(CH3)2SiO 2 / 2 ] 12.2 (SiO 4 / 2 ) 12.1

[0068] R1 represents cyclohexane group, R2 represents methyl silicon diethoxy group (-Si(CH3)-(OCH2CH3)2

[0069] Preparation of anti-poisoned platinum gold catalyst of Example 2

[0070] The preparation of anti-poisoned platinum gold catalyst provided in this example includes the following steps: in a 5L reaction device, 300 grams of chloroplatinic acid, 1500 ml of isopropanol and 1200 grams of dimethyl divinyl disiloxane, 200 grams of isopropoxy aluminum, 150 grams of silicon ethyl cyclohexyl imidazole tetrafluoroboric acid salt, 400 grams of sodium methoxide are added with stirring, and the reaction is carried out at 65-75°C for 3h, then cooled, the solid salt is filtered out, and the volume is adjusted to 5000 ppm / L with xylene to obtain an anti-poisoned catalyst, and the structure is as follows:

[0071]

[0072] Preparation of surface layer liquid silicone rubber of Example 3

[0073] The preparation of the surface liquid silicone rubber provided in this embodiment includes the following steps: 5 kg of diene silicone oil with a viscosity of 10000 cs, 3.5 kg of fumed silica with a specific surface area of ​​300 m² / g, 400 g of hexamethyldisilazane, and 80 g of water are added to a kneader. The mixture is kneaded at 80°C for 2 hours, then heated to 180°C and kneaded under vacuum for 3 hours. Low-boiling substances are removed by vacuuming, the mixture is cooled and discharged, and 200 g of the branched MDQ resin slip agent provided in Example 3, 2 kg of ethylene MQ resin with a vinyl content of 2%, ethynylcyclohexanol, and 20 ppm of Castrol platinum catalyst are added sequentially. After uniform dispersion, 300 g of hydrogen-containing silicone oil with a viscosity of 40 cs and a hydrogen content of 0.85% is added to prepare the high-performance surface liquid silicone rubber.

[0074] Example 4: Preparation of Intermediate Layer Liquid Silicone Rubber

[0075] The preparation of the intermediate layer liquid silicone rubber provided in this embodiment includes the following steps: adding 2 kg of diene silicone oil with a viscosity of 20000 cs and 1 kg of diene silicone oil with a specific surface area of ​​300 m² to a kneader. 2 2 kg of fumed silica (by weight / g), 200 g of hexamethyldisilazane, and 40 g of water were kneaded at 80°C for 2 hours, then heated to 180°C and kneaded under vacuum for 3 hours. Low-boiling-point substances were removed by vacuuming, and the mixture was cooled and discharged. Ethynylcyclohexanol and 20 ppm of Castrol platinum catalyst were added sequentially, and after uniform dispersion, 110 g of hydrogen-containing silicone oil with a viscosity of 15 cs and a hydrogen content of 0.25% was added to prepare a high-performance intermediate layer liquid silicone rubber.

[0076] Example 5: Preparation of the adhesive layer liquid silicone rubber

[0077] The preparation of the adhesive layer liquid silicone rubber provided in this embodiment includes the following steps: 5 kg of vinyl silicone oil with a specific surface area of ​​300 m² is added to a kneader. 2 3 kg of fumed silica (by weight / g), 300 g of hexamethyldisilazane, and 50 g of water were kneaded at 70°C for 2 hours, then heated to 180°C and kneaded under vacuum for 3 hours. Low-boiling-point substances were removed by vacuuming, and the mixture was cooled and discharged. 250 g of tackifier (a 1:1 mixture of commercially available KH560 and KH570 silane coupling agents), 30 g of ethynylcyclohexanol, and 200 g of the anti-poisoning platinum catalyst provided in Example 2 were added. After uniform dispersion, 180 g of hydrogen-containing silicone oil with a viscosity of 35 cs and a hydrogen content of 1% was added to prepare the adhesive layer liquid silicone rubber.

[0078] Example 6:

[0079] The simulated sheepskin prepared in this embodiment is as follows: Figure 1 As shown, from top to bottom, the layers are: surface layer 1, middle layer 2, adhesive layer 3, and second layer of sheepskin 4.

[0080] A first layer of topcoat liquid silicone rubber prepared in Example 3 was coated on a release paper at a coating thickness of 20 micrometers, and after baking at 115°C for 6 minutes in an oven until surface dry; a second layer of intermediate layer liquid silicone rubber prepared in Example 4 was coated at a coating thickness of 120 micrometers, and after baking at 115°C for 6 minutes in an oven until surface dry; and a layer of adhesive layer liquid silicone rubber prepared in Example 5 was coated at a coating thickness of 100 micrometers, and after bonding to the two layers of sheepskin and baking at 130°C for 5 minutes in an oven until fully vulcanized. The coated product was peeled off from the release paper and wound up.

[0081] Example 7:

[0082] The preparation method of this example was as shown in Example 6, but the coating thicknesses were 50 micrometers, 120 micrometers, and 100 micrometers, in that order.

[0083] Example 8:

[0084] The preparation method of this example was as shown in Example 6, but the coating thicknesses were 100 micrometers, 100 micrometers, and 100 micrometers, in that order.

[0085] Example 9:

[0086] The preparation method of this example was as shown in Example 6, but the coating thicknesses were 50 micrometers, 100 micrometers, and 200 micrometers, in that order.

[0087] Example 10: Simulated sheepskin without carbene ligand anti-poisoning catalyst

[0088] The preparation method of this example was as shown in Example 6, but the adhesive layer liquid silicone rubber did not contain 10 ppm of carbene ligand anti-poisoning catalyst, and instead contained 20 ppm of Kast catalyst.

[0089] Example 11: Simulated sheepskin without branched resin slip agent

[0090] The preparation method of this example was as shown in Example 6, but the topcoat liquid silicone rubber did not contain branched resin slip agent, and instead contained 500 cs dimethyl silicone oil.

[0091] Example 12: Simulated sheepskin without intermediate layer liquid silicone rubber

[0092] The simulated sheepskin prepared in this example was as shown in Figure 2 , in which the topcoat layer 1, the adhesive layer 3, and the two layers of sheepskin 4 were arranged in that order from top to bottom.

[0093] A first layer of the surface layer liquid silicone rubber provided in Example 3 was coated on a release paper at a coating thickness of 20 microns, and after oven drying at 115°C for 6 minutes, a second layer of the adhesive layer liquid silicone rubber provided in Example 5 containing 10 ppm of the carbene ligand resistant anti-poisoning catalyst was coated at a coating thickness of 100 microns, and two layers of sheepskin were attached, and after sufficient vulcanization in an oven at 130°C for 5 minutes, the coated product was peeled off from the release paper and wound up.

[0094] Example 13 Simulated Sheepskin Without Coating of the Intermediate Layer Liquid Silicone Rubber

[0095] A first layer of the surface layer liquid silicone rubber provided in Example 3 was coated on a release paper at a coating thickness of 80 microns, and after oven drying at 115°C for 6 minutes, a second layer of the adhesive layer liquid silicone rubber provided in Example 5 containing 10 ppm of the carbene ligand resistant anti-poisoning catalyst was coated at a coating thickness of 100 microns, and two layers of sheepskin were attached, and after sufficient vulcanization in an oven at 130°C for 5 minutes, the coated product was peeled off from the release paper and wound up.

[0096] Example 14 Test Analysis

[0097] This example is directed to the simulated sheepskin prepared in Examples 6-13, and the resilience, hand feeling, smoothness, and surface hand feeling were tested.

[0098] The testing method for resilience was to score the time for returning to the original state after stretching, and the score was from 1 to 5 corresponding to the recovery time from long to short;

[0099] Adhesive strength test

[0100] Three pieces of leather samples with a length of 150 mm and a width of 30 mm were cut according to the provisions of GB / T8949-2008, and the coating layer was pasted together with the same type of leather coating layer using an appropriate amount of adhesive silicone (the sample must be firmly bonded), and then the bonded sample was placed in a constant temperature of 135°C for 2 h, and after the bonding treatment, the sample was hand peeled, and the coating layer and the base fabric were separated to 50 mm, and then the two separated ends were clamped on the clamps of a tensile testing machine, and the peel was carried out at a speed of 200 mm / min, and the maximum load of the sample peel was recorded.

[0101] Folding resistance test

[0102] The test was carried out according to the provisions of QB / T2714-2005. Two pieces of sample were cut for each of the four groups according to the standard provisions. Then the sample was folded with the front side inside, and each group of samples was folded at a folding frequency of 10 million times under the condition of a temperature of (23±2) °C, and the changes of the front and back sides of the folded parts were observed, and the results were determined according to the provisions of 5.10.2 of QB / 1646-1992.

[0103] Smoothness test: 2-3 volunteers test the leather hand feeling, fold two pieces of synthetic leather and rub them, and score 1-5 according to the difficulty of rubbing, from rough to smooth;

[0104] Stain resistance test

[0105] Test method: test according to the provisions of CFFA-141.

[0106] Evaluation criteria: 1st grade stain completely cannot be removed; 2nd grade large area stain; 3rd grade slight stain trace; 4th grade stain completely removed.

[0107] The test results are shown in Table 1,

[0108] Table 1, test results

[0109]

[0110] It can be seen from comparative example 8 and example 7 that when the coating thickness of the surface layer liquid silicone rubber is relatively thick, the prepared simulated sheepskin has a relatively hard elastic hand feeling, and the folding resistance test shows that there is a slight cracking phenomenon.

[0111] It can be seen from comparative example 9 and example 7 that when the coating thickness of the adhesive layer liquid silicone rubber is relatively thick, the prepared simulated sheepskin has a relatively hard elastic hand feeling, and the comprehensive simulation degree is low.

[0112] It can be seen from comparative example 10 and example 7 that when the adhesive layer liquid silicone rubber does not contain 10 ppm of the carbene ligand anti-poisoning catalyst, and 20 ppm of the Karstedt platinum gold catalyst is used instead, the adhesive strength of the prepared simulated sheepskin is reduced, causing delamination problem, poor elasticity, and the folding resistance test fails.

[0113] It can be seen from comparative example 11 and example 7 that when the surface layer liquid silicone rubber does not contain branched chain resin smoothness agent, the prepared simulated sheepskin has a relatively high friction coefficient, and the smoothness is obviously decreased.

[0114] It can be seen from comparative example 12 and example 7 that when the intermediate layer liquid silicone rubber is not coated, the prepared simulated sheepskin has a relatively hard elastic hand feeling and poor elasticity.

[0115] As can be seen from example 7, the method provided by the application can be used to prepare simulated sheepskin with high elasticity, high adhesive strength, good stain resistance, excellent smoothness and good surface hand feeling.

[0116] Selection of branched chain resin smoothness agent addition ratio in example 15

[0117] The example adopts the method provided in example 6 to prepare simulated sheepskin, wherein the content of branched resin slip agent added in the surface layer liquid silicone rubber is 1%, 3%, 5%, 7%, 9% and 11% respectively. The prepared simulated sheepskin is detected for its resilience, bonding strength, folding fastness, slip degree and surface hand feeling, and the comprehensive simulation degree is calculated. The detection method is shown in example 13, and the detection result is shown in table 2.

[0118] Table 2, selection of branched resin slip agent addition ratio

[0119]

[0120] As shown in table 2, when the content of branched resin slip agent in the surface layer liquid silicone rubber is 5-7%, the resilience of the prepared simulated sheepskin is excellent, the bonding strength, folding fastness and stain resistance reach a high level, and the slip degree is high and the surface hand feeling is good. With the continuous increase of the content of branched resin slip agent, the resilience decreases obviously, and the folding fastness test result shows that cracks appear on the surface, which may have a certain negative impact on the interlayer adhesion or flexibility. Therefore, the content of branched resin slip agent is preferably 5-7%.

[0121] Example 16 influence of surface layer liquid silicone rubber on simulated sheepskin

[0122] This example adjusts the ratio of SiH / SiVi in the surface layer liquid silicone rubber of example 3, and compares the influence of the surface layer liquid silicone rubber on the performance of simulated sheepskin

[0123] This example adopts the coating method provided in example 7 to prepare simulated sheepskin, and the detection method is shown in example 13. The detection result is shown in table 3.

[0124] Table 3, influence of surface layer liquid silicone rubber selection on simulated sheepskin

[0125]

[0126]

[0127] As shown in table 3, the ratio of SiH / SiVi (the ratio of silicon hydrogen bond in hydrogen-containing silicone oil to total silicon vinyl bond in the rubber) has a great influence on simulated sheepskin. When the ratio of SiH / SiVi is small, the rubber is sticky, the interlayer adhesion is poor, and the stain resistance is also low. When the ratio of SiH / SiVi is too large, the rubber film is brittle, the elongation is low, and it is easy to crack. The stain resistance also decreases. The preferred range of the ratio of SiH / SiVi is 1:1-1:1.7, and the performance is good in this range.

[0128] Example 17 influence of intermediate layer liquid silicone rubber on simulated sheepskin

[0129] The present example adjusts the modulus of elasticity of the intermediate layer in Example 4. The modulus of elasticity of the silicone rubber can be adjusted by changing the proportion of fumed white carbon black or the proportion of hydrogen content of the hydrogen-containing silicone oil by a method well known in the industry. The effect of the modulus of elasticity of the intermediate layer liquid silicone rubber on the performance of the simulated sheepskin is investigated.

[0130] The present example uses the coating method provided in Example 7 to prepare simulated sheepskin. The detection method is as shown in Example 13, and the detection results are shown in Table 4.

[0131] Table 4: Effect of selection of intermediate layer liquid silicone rubber on simulated sheepskin

[0132]

[0133] As can be seen from Table 4, the modulus of elasticity of the intermediate layer has a small effect on the stain resistance. When the modulus of elasticity is too low, although there is good softness, the interlayer adhesion is low and slightly sticky, the interlayer bonding strength is small, and the resistance to folding test is prone to cracking. When the modulus of elasticity is 0.5 MPa, the comprehensive performance is good. As the modulus of elasticity continues to increase, the hand gradually becomes hard and plastic, and the overall simulation level decreases.

[0134] Although the present application is disclosed as above, the present application is not limited thereto. Any person skilled in the art, without departing from the spirit and scope of the present application, can make various changes and modifications, therefore the scope of protection of the present application should be subject to the scope defined by the claims.

Claims

1. A simulated sheepskin, characterized in that, The structure, from top to bottom, comprises a top layer, an intermediate layer, an adhesive layer, and a second layer of sheepskin. The top layer is coated with a liquid silicone rubber, which includes a branched-chain resin slip agent, specifically [R1(CH2)3-Si(CH3)2O]. 1 / 2 ]3[R2 CH2CH2-Si(CH3)2O 1 / 2 ]5.8[(CH3)3SiO 1 / 2 ]8 [(CH3)2SiO 2 / 2 ] 12.2 (SiO 4 / 2 ) 12.1， Wherein, R1 represents cyclohexyl, and R2 represents methylsilyldiethoxy (-Si(CH3)-(OCH2CH3)2). The intermediate layer uses a foamed silicone coating or liquid silicone rubber with an elastic modulus lower than 2 MPa; the adhesive layer contains a ligand-complexed platinum catalyst, wherein the ligand is any one or more of polyphenylphosphine ligands, hindered amine ligands, carbene ligands, and modified vinylsiloxane ligands; the content of the branched organosilicon resin slip agent in the surface liquid silicone rubber is 3% to 8%; the SiH / SiVi ratio in the surface liquid silicone rubber is 1.2:1 to 1.7:1; The total thickness of the top layer liquid silicone rubber, the intermediate layer liquid silicone rubber, and the adhesive layer liquid silicone rubber is 50-300μm. The coating thickness of the top layer liquid silicone rubber is 5-100μm, the coating thickness of the intermediate layer liquid silicone rubber is 20-200μm, and the coating thickness of the adhesive layer liquid silicone rubber is 20-200μm. The preparation method of the surface liquid silicone rubber is as follows: vinyl silicone oil, high specific surface area silica, silazane, and water are added to a kneader and kneaded at 70°C for 2 hours. The temperature is then raised to 180°C and kneaded under vacuum for 3 hours. Low-boiling substances are removed under vacuum, and the material is cooled and discharged. A certain proportion of branched organosilicon resin slip agent and vinyl MQ silicone resin are added. Ethynylcyclohexanol and platinum catalyst are added successively. After uniform dispersion, a hydrogen-containing crosslinking agent is added to prepare solvent-free liquid silicone rubber.

2. The method for preparing simulated sheepskin as described in claim 1, characterized in that, Includes the following steps: (1) Coat the release paper with liquid silicone rubber and bake until surface dry; (2) Apply an intermediate layer of liquid silicone rubber to the surface layer and bake until surface dry; (3) Apply an adhesive layer of liquid silicone rubber to the intermediate layer; (4) Attach the adhesive layer to the two layers of sheepskin, heat and vulcanize, peel it off from the release paper, and roll it up; or (1) Coat the release paper with liquid silicone rubber and bake until surface dry; (2) Apply an adhesive layer of liquid silicone rubber to the surface layer; (3) Attach the adhesive layer to the two layers of sheepskin, heat and vulcanize, peel it off from the release paper, and roll it up; The surface layer liquid silicone rubber contains a branched-chain resin slip agent, which is... [R1(CH2)3-Si(CH3)2O 1 / 2 ]3[R2 CH2CH2-Si(CH3)2O 1 / 2 5.8[(CH3)3SiO 1 / 2 [8 [(CH3)2SiO] 2 / 2 ] 12.2 (SiO 4 / 2 ) 12.1， Wherein, R1 represents cyclohexyl, and R2 represents methylsilyl diethoxy (-Si(CH3)-(OCH2CH3)2); the intermediate layer is made of foamed silicone or low-modulus high-strength liquid silicone rubber; the adhesive layer is low-modulus liquid silicone rubber.

3. The method as described in claim 2, characterized in that, The preparation method of the branched organosilicon resin slip agent is as follows: hydrogen-containing MDQ resin, allyl monomer, and vinyl silane coupling agent are added to a three-necked flask, heated to a certain temperature, a platinum complexing catalyst is added, and the reaction is continued until no SiH bond residue remains. The product is then cooled and discharged. The branched resin slip agent includes branched siloxane compounds with reactive alkoxy and hydroxyl groups. The branched resin slip agent is a self-crosslinking MDQ silicone resin with alkoxy functional groups.

4. The method as described in claim 3, characterized in that, The adhesive layer liquid silicone rubber contains a ligand complexed with a platinum catalyst, wherein the ligand is any one or more of polyphenylphosphine ligands, hindered amine ligands, carbene ligands, and modified vinylsiloxane ligands.

5. The method as described in claim 4, characterized in that, The ligand is a modified carbene ligand; the molar ratio of the carbene ligand to the Pt atom is 1:1 to 3:

1.

6. The method as described in claim 5, characterized in that, The method for preparing the carbene ligand complexed platinum catalyst is as follows: In a reaction apparatus, chloroplatinic acid, isopropanol, divinyltetramethyltetraphenyldisiloxane, aluminum isopropoxy, and N-heterocyclic imidazole salt are added, methanol is slowly added under stirring, and the reaction is stirred at 65-75℃ for 3 hours. After cooling, the solid salt is filtered off, and the volume is adjusted with xylene to obtain the catalyst.

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