Silicon-based solvent-free polyurethane composite artificial leather and preparation method thereof

Abstract

The invention discloses silicon-based solvent-free polyurethane composite artificial leather and a preparation method thereof.The composite artificial leather comprises a surface layer, a middle layer, a bonding layer and a base cloth layer from top to bottom, and the surface layer is prepared by coating release paper with surface layer slurry and drying the release paper; the surface layer slurry comprises water-based resin containing carboxyl siloxane polyurethane resin copolymer, and the preparation method comprises the following steps: carrying out polymerization reaction on hydroxyl polyether-terminated dihydroxyl polydimethylsiloxane, carboxylic acid with double hydroxyl groups and diisocyanate, adding inorganic alkali to obtain carboxyl siloxane polyurethane resin copolymer water dispersion liquid, and adding the water-based resin containing carboxyl siloxane polyurethane resin copolymer into the water-based resin containing carboxyl siloxane polyurethane resin copolymer to obtain the water-based resin containing carboxyl siloxane polyurethane resin copolymer. Adding the mixture into waterborne polyurethane resin; the molecular formula of the hydroxyl polyether-terminated dihydroxyl polydimethylsiloxane is H-O-R-[Si (CH3) 2O] m-R-O-H, m is a positive integer from 25 to 95, R represents a polyether chain segment with the following structure:-O-(C2H4O) p-(C3H6O) q-, p and q are integers from 0 to 15, and p + q is greater than or equal to 1 and less than or equal to 15. The composite artificial leather disclosed by the invention is easy to clean and care, super soft, glossy and transparent, low in odor and VOC (Volatile Organic Compounds) and good in wear resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of polyurethane composite materials, and particularly relates to a silicon-based solvent-free polyurethane composite artificial leather and a preparation method thereof. Background Art

[0002] The current preparation technology and large-scale application of silicon-based polyurethane composite artificial leather are internationally recognized problems. Existing products have three highs (high pollution, high energy consumption, and high emissions), low interface bonding strength of silicon-based polyurethane composite materials, poor stability, and single product function. Summary of the invention

[0004] The invention provides a silicon-based solvent-free polyurethane composite artificial leather and a preparation method thereof. The prepared composite artificial leather is easy to clean and care for, is super soft, has a high gloss and transparency, has low odor and VOC, and has good wear resistance.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a silicon-based solvent-free polyurethane composite artificial leather, the composite artificial leather comprising, from top to bottom, an epidermis layer, an intermediate layer, an adhesive layer and a base fabric layer; the epidermis layer is made by coating an epidermis layer slurry on a release paper and drying it;

[0007] The epidermis slurry comprises an aqueous resin containing a carboxyl siloxane polyurethane resin copolymer, and the preparation method of the aqueous resin containing a carboxyl siloxane polyurethane resin copolymer is as follows: a hydroxyl polyether-terminated dihydroxy polydimethylsiloxane, a carboxylic acid with a dihydroxy group and a diisocyanate are polymerized, an inorganic base is added to obtain an aqueous dispersion of the carboxyl siloxane polyurethane resin copolymer, and the aqueous dispersion is added to the aqueous polyurethane resin to obtain the aqueous resin containing the carboxyl siloxane polyurethane resin copolymer;

[0008] The molecular formula of the hydroxy polyether-terminated dihydroxy polydimethylsiloxane is:

[0009] HOR-[Si(CH3)2O] m -ROH

[0010] Wherein, m is a positive integer of 25-95, and R represents a polyether segment of the following structure: -O-(C2H4O) p -(C3H6O) q -, p, q are integers of 0-15, and 1≤p+q≤15.

[0011] In the above technical solution, the inorganic base is one of sodium carbonate, potassium carbonate, sodium hydroxide and potassium hydroxide.

[0012] In the above technical scheme, the skin layer slurry also includes an aqueous leveling agent, an aqueous defoaming agent and an anti-wear agent. The mass ratio of the aqueous resin, aqueous leveling agent, aqueous defoaming agent and anti-wear agent of the carboxyl silicone polyurethane resin copolymer is: 100: (0.1-1): (0.1-0.5): (0.1-1).

[0013] In the above technical solution, the waterborne polyurethane resin is a waterborne polyether two-component resin with a solid content of 40%-60%.

[0014] In the above technical solution, the bonding layer is made by coating the bonding layer slurry, and the bonding layer slurry is prepared by polyether resin A material, polyether resin B material and a catalyst;

[0015] The polyether resin material A is composed of a prepolymer, a chain extender, a foaming agent and a stabilizer, wherein the prepolymer is obtained by reacting a diisocyanate and a polyether polyol, and the polyether resin material B is composed of an aromatic polyisocyanate, a polyether diol and a functional filler.

[0016] In the above technical solution, the mass ratio of the polyether resin A material, the polyether resin B material and the catalyst is 100:110:(0.1-0.5).

[0017] In a second aspect, the present invention provides a method for preparing a silicon-based solvent-free polyurethane composite artificial leather, comprising the following steps:

[0018] Step (1), preparation of the epidermis layer: coating the epidermis layer slurry on release paper and drying to obtain the epidermis layer;

[0019] The epidermis slurry comprises an aqueous resin containing a carboxyl siloxane polyurethane resin copolymer, and the preparation method of the aqueous resin containing a carboxyl siloxane polyurethane resin copolymer is as follows: a hydroxyl polyether-terminated dihydroxy polydimethylsiloxane, a carboxylic acid with a dihydroxy group and a diisocyanate are polymerized, an inorganic base is added to obtain an aqueous dispersion of the carboxyl siloxane polyurethane resin copolymer, and the aqueous dispersion is added to the aqueous polyurethane resin to obtain the aqueous resin containing the carboxyl siloxane polyurethane resin copolymer;

[0020] The molecular formula of the hydroxy polyether-terminated dihydroxy polydimethylsiloxane is:

[0021] HOR-[Si(CH3)2O] m -ROH

[0022] Wherein, m is a positive integer of 25-95, and R represents a polyether segment of the following structure: -O-(C2H4O) p -(C3H6O) q -, p, q are integers from 0 to 15, and 1≤p+q≤15;

[0023] Step (2), preparation of the intermediate layer: coating the intermediate layer slurry on the dried epidermal layer and drying to obtain the intermediate layer;

[0024] Step (3), preparing the bonding layer: coating the bonding layer slurry on the dried intermediate layer and drying to obtain the bonding layer;

[0025] Step (4), bonding the base fabric layer: bonding the adhesive layer to the base fabric, separating and rolling up after aging, to obtain the composite artificial leather.

[0026] In the above technical scheme, in step (1), the inorganic base is one of sodium carbonate, potassium carbonate, sodium hydroxide and potassium hydroxide.

[0027] The beneficial effects of the present invention are:

[0028] 1. The present invention adopts carboxyl siloxane polyurethane resin copolymer slurry for surface sealing, which has better gloss and transparency than other siloxane polymer resins, and has the characteristics of easy decontamination, folding resistance, wear resistance and hydrolysis resistance.

[0029] 2. The adhesive layer slurry of the present invention utilizes resin reaction and high-speed physical stirring to control the softness of the solvent-free polyurethane after drying, while meeting the high physical property requirements of synthetic leather, so that the product finally has a soft touch and ultra-high physical properties.

[0030] 3. The composite artificial leather prepared by the present invention is easy to clean and maintain, is super soft, has good gloss and transparency, low odor and VOC, and good wear resistance. DETAILED DESCRIPTION

[0031] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. The present invention can be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. On the contrary, these embodiments are provided so that this disclosure will be thorough and complete, and the concept of the present invention will be fully conveyed to those skilled in the art, and the present invention will only be limited by the claims.

[0032] The present invention provides a silicon-based solvent-free polyurethane composite artificial leather, the composite artificial leather comprises a skin layer, an intermediate layer, a bonding layer and a base fabric layer from top to bottom, and a preparation method thereof comprises the following steps:

[0033] Step (1), preparation of the epidermis: coating the epidermis slurry on the release paper and drying to obtain the epidermis. The coating knife position is 0.03-0.15mm, the texture of the release paper is transferred to the surface, and the epidermis is dried to form a film with a thickness of 0.01-0.1mm.

[0034] The epidermis slurry includes an aqueous resin containing a carboxyl siloxane polyurethane resin copolymer, and the preparation method of the aqueous resin containing a carboxyl siloxane polyurethane resin copolymer is as follows: a hydroxyl polyether-terminated dihydroxy polydimethylsiloxane, a carboxylic acid with a dihydroxy group and a diisocyanate are polymerized, an inorganic base is added to obtain an aqueous dispersion of the carboxyl siloxane polyurethane resin copolymer, and the aqueous dispersion is added to the aqueous polyurethane resin to obtain the aqueous resin containing the carboxyl siloxane polyurethane resin copolymer;

[0035] The molecular formula of hydroxy polyether terminated dihydroxy polydimethylsiloxane is:

[0036] HOR-[Si(CH3)2O]mROH

[0037] Wherein, m is a positive integer of 25-95, preferably m=40-70. R represents a polyether segment of the following structure: -O-(C2H4O)p-(C3H6O)q-, p and q are integers of 0-15, and 1≤p+q≤15.

[0038] The inorganic base is one of sodium carbonate, potassium carbonate, sodium hydroxide and potassium hydroxide.

[0039] Waterborne polyurethane resin is a waterborne polyether type two-component resin with a solid content of 40%-60%.

[0040] In addition, the skin layer slurry includes not only the aqueous resin containing the carboxyl silicone polyurethane resin copolymer, but also an aqueous leveling agent, an aqueous defoaming agent and an anti-wear additive. The mass ratio of the aqueous resin containing the carboxyl silicone polyurethane resin copolymer, the aqueous leveling agent, the aqueous defoaming agent and the anti-wear additive is: 100: (0.1-1): (0.1-0.5): (0.1-1).

[0041] The water-based leveling agent is preferably a silicone-modified polyether water-based leveling agent such as BYK-346 and BYK-348.

[0042] The aqueous defoamer is preferably a silicone-modified defoaming agent such as BYK-024 and BYK-054.

[0043] The wear-resistant additive is preferably an inorganic filler such as talcum powder and nano-aluminum oxide.

[0044] Step (2), preparation of the intermediate layer: coating the intermediate layer slurry on the dried epidermis layer and drying to obtain the intermediate layer. The coating knife position is 0.05-0.2mm, and the intermediate layer film thickness after drying is 0.03-0.1mm.

[0045] The middle layer slurry is prepared from water-based polyurethane resin, water-based leveling agent, water-based defoaming agent and water-based color paste, and the mass ratio of water-based polyurethane resin, water-based leveling agent, water-based defoaming agent and water-based color paste is 100: (0.1-1): (0.1-0.5): (3-20).

[0046] Waterborne polyurethane resin is a waterborne polyether type two-component resin with a solid content of 40%-60%.

[0047] The water-based leveling agent is preferably a silicone-modified polyether water-based leveling agent such as BYK-346 and BYK-348.

[0048] The aqueous defoamer is preferably a silicone-modified defoaming agent such as BYK-024 and BYK-054.

[0049] Step (3), preparation of bonding layer: coating the bonding layer slurry on the dried intermediate layer and drying to obtain the bonding layer. Coating knife position: 0.2-0.4 mm.

[0050] The bonding layer slurry is prepared from polyether resin A material, polyether resin B material and a catalyst, and the mass ratio of the polyether resin A material, the polyether resin B material and the catalyst is 100:110:(0.1-0.5).

[0051] Among them, polyether resin A material is composed of prepolymer, chain extender, foaming agent and stabilizer, and polyether resin B material is composed of aromatic polyisocyanate, polyether diol and functional filler. The selected resins are screened through a large number of resin types, with the hydroxyl value controlled at 90-97 and the NCO equivalent controlled at 270-290, which can ensure good adhesion between the bonding layer and the middle layer and the base fabric layer.

[0052] The prepolymer is obtained by the reaction of diisocyanate and polyether polyol.

[0053] The chain extender is one of N-methyldiethanolamine, N,N-dihydroxyethylaniline, bisphenol A dihydroxyethyl ether, bisphenol A dihydroxypropyl ether, 3,3'-dichloro-4,4'-diaminophenylmethane (MOCA), diethyltoluenediamine (DETDA), 4,4'-methylene-bis(3-chloro-2,6-diethylaniline) (MCDEA) and di-sec-butylaminodiphenylmethane (MDBA).

[0054] The blowing agent is one of water, HCFC (hydrochlorofluorocarbon), HFC (hydrofluorocarbon), HC (alkane), and liquid CO2.

[0055] The stabilizer is pentaerythritol diphosphate or an organosilicon surfactant.

[0056] The functional filler is one of modified cellulose nanocrystals, carbon nanotubes, graphene oxide, and hollow titanium dioxide microspheres.

[0057] The catalyst is one of triethylenediamine, bis(dimethylaminoethyl)ether, triethanolamine, pyridine, N,N-dimethylpyridine and organic bismuth catalyst.

[0058] In addition, through experimental comparison, during the preparation of the bonding layer slurry, the carbon dioxide gas produced by the reaction is evenly dispersed in the slurry through physical stirring, and the stirring speed is controlled at 1000-1200rpm to ensure appropriate softness.

[0059] Step (4), laminating the base fabric layer, laminating the adhesive layer to the base fabric, separating and rolling up after aging, and obtaining the composite artificial leather.

[0060] Among them, resins with different solid contents are selected according to the grammage of the base fabric, and the base fabric can be non-woven fabric, woven fabric, knitted fabric, microfiber, etc.

[0061] The curing process is as follows: put the laminated base fabric + coating + release paper into the oven for curing, set the temperature at 125-145℃, and the drying time is 5-15 minutes;

[0062] The separation and rewinding process is: the matured finished product + release paper passes through the guide roller and two rewinding devices, is separated and rewound, the finished product is on the finished product rewinding rack, and the release paper is on the release paper rewinding rack.

[0063] In summary, the preparation method of the present invention has the following advantages:

[0064] 1. Interface bonding technology: Through the selection of water-based polyether type intermediate layer resin, the optimized matching of water-based slurry containing carboxyl silicone polyurethane resin on the surface layer and polyether type solvent-free resin on the bonding layer, similar compatibility is used to achieve the characteristics of high overall interface bonding strength and diverse functions.

[0065] 2. High-speed stirring solvent-free mixing technology: The adhesive layer mixes the solvent-free AB material components, stirs them at high speed using a physical mechanical stirrer, foams them in an oven, and solidifies them in combination with the base fabric layer. The purpose is to reduce the weight of synthetic leather per unit area, increase the overall softness of the product, and improve the feel.

[0066] 3. Optimized selection of resin: The addition of carboxylsiloxane polyurethane resin copolymer makes the seal layer more transparent and glossy, and it is also easy to remove dirt and clean. The design of the ratio of solvent-free AB materials, the optimization design of catalyst type and dosage, the design of oven drying parameters and stirring speed can realize the control requirements of solvent-free foaming and bonding process, and achieve the high physical property requirements of folding resistance, wear resistance and hydrolysis resistance.

[0067] The composite artificial leather prepared by the present invention can be widely used in the fields of home interior decoration, vehicle seats, wearable electronic products, medical sponges, etc.

[0068] After the composite artificial leather is prepared by the preparation method of the present invention, the softness, 100,000 times folding resistance at room temperature, hydrolysis resistance, and 100,000 times Martindale abrasion resistance tests are performed according to the national standard and industry standard for synthetic leather. The test results are shown in Table 1.

[0069] Table 1 Experimental test results

[0070]

[0071] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A silicon-based solvent-free polyurethane composite artificial leather, the composite artificial leather comprising, from top to bottom, an epidermis layer, an intermediate layer, an adhesive layer and a base fabric layer; characterized in that: The epidermis layer is made by coating the epidermis slurry on release paper and drying it; The epidermis slurry comprises an aqueous resin containing a carboxyl siloxane polyurethane resin copolymer, and the preparation method of the aqueous resin containing a carboxyl siloxane polyurethane resin copolymer is as follows: a hydroxyl polyether-terminated dihydroxy polydimethylsiloxane, a carboxylic acid with a dihydroxy group and a diisocyanate are polymerized, an inorganic base is added to obtain an aqueous dispersion of the carboxyl siloxane polyurethane resin copolymer, and the aqueous dispersion is added to the aqueous polyurethane resin to obtain the aqueous resin containing the carboxyl siloxane polyurethane resin copolymer; The molecular formula of the hydroxy polyether-terminated dihydroxy polydimethylsiloxane is: HOR-[Si(CH3)2O] m -ROH Wherein, m is a positive integer of 25-95, and R represents a polyether segment of the following structure: -O-(C2H4O) p -(C3H6O) q -, p, q are integers of 0-15, and 1≤p+q≤15.

2. The composite artificial leather according to claim 1, characterized in that: The inorganic base is one of sodium carbonate, potassium carbonate, sodium hydroxide and potassium hydroxide.

3. The composite artificial leather according to claim 1, characterized in that: The skin layer slurry also includes an aqueous leveling agent, an aqueous defoaming agent and an anti-wear agent. The mass ratio of the aqueous resin, aqueous leveling agent, aqueous defoaming agent and anti-wear agent of the carboxyl silicone polyurethane resin copolymer is: 100: (0.1-1): (0.1-0.5): (0.1-1).

4. The composite artificial leather according to claim 1, characterized in that: The waterborne polyurethane resin is a waterborne polyether two-component resin with a solid content of 40%-60%.

5. The composite artificial leather according to claim 1, characterized in that: The bonding layer is made by coating a bonding layer slurry, and the bonding layer slurry is prepared from a polyether resin A material, a polyether resin B material and a catalyst; The polyether resin material A is composed of a prepolymer, a chain extender, a foaming agent and a stabilizer, wherein the prepolymer is obtained by reacting a diisocyanate and a polyether polyol, and the polyether resin material B is composed of an aromatic polyisocyanate, a polyether diol and a functional filler.

6. The composite artificial leather according to claim 5, characterized in that: The mass ratio of the polyether resin A material, the polyether resin B material and the catalyst is 100:110:(0.1-0.5).

7. A method for preparing a silicon-based solvent-free polyurethane composite artificial leather, characterized in that: The following steps are involved: Step (1), preparation of the epidermis layer: coating the epidermis layer slurry on release paper and drying to obtain the epidermis layer; The epidermis slurry comprises an aqueous resin containing a carboxyl siloxane polyurethane resin copolymer, and the preparation method of the aqueous resin containing a carboxyl siloxane polyurethane resin copolymer is as follows: a hydroxyl polyether-terminated dihydroxy polydimethylsiloxane, a carboxylic acid with a dihydroxy group and a diisocyanate are polymerized, an inorganic base is added to obtain an aqueous dispersion of the carboxyl siloxane polyurethane resin copolymer, and the aqueous dispersion is added to the aqueous polyurethane resin to obtain the aqueous resin containing the carboxyl siloxane polyurethane resin copolymer; The molecular formula of the hydroxy polyether-terminated dihydroxy polydimethylsiloxane is: HOR-[Si(CH3)2O] m -ROH Wherein, m is a positive integer of 25-95, and R represents a polyether segment of the following structure: -O-(C2H4O) p -(C3H6O) q -, p, q are integers from 0 to 15, and 1≤p+q≤15; Step (2), preparation of the intermediate layer: coating the intermediate layer slurry on the dried epidermal layer and drying to obtain the intermediate layer; Step (3), preparation of the bonding layer: coating the bonding layer slurry on the dried intermediate layer and drying to obtain the bonding layer; Step (4), bonding the base fabric layer: bonding the adhesive layer to the base fabric, separating and rolling up after aging, to obtain the composite artificial leather.

8. The preparation method according to claim 7, characterized in that: In step (1), the inorganic base is one of sodium carbonate, potassium carbonate, sodium hydroxide and potassium hydroxide.

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