EP-4735496-A1 - SILICONE LEATHER COATING COMPOSITION

EP4735496A1EP 4735496 A1EP4735496 A1EP 4735496A1EP-4735496-A1

Abstract

The present disclosure relates to a method for preparing a carbinol terminated silicone/polyurethane hybrid prepolymer based coating composition (v) comprising the steps of (A) Preparing a carbinol terminated silicone/polyurethane hybrid prepolymer; and (B) preparing the carbinol terminated silicone/polyurethane hybrid prepolymer based coating composition (v) by mixing the carbinol terminated silicone/polyurethane hybrid prepolymer produced in (A) ( (v) (a) ) with optional cured silicone elastomer powder (v) (b); optional silicon-free organic particles and/or microparticles (v) (c); a polyorganosiloxane containing at least two or alternatively at least three silicon bonded hydrogen (-Si-H) groups per molecule (v) (d); a polyisocyanate having three or more isocyanate groups per molecule in an amount such that the molar ratio of -OH groups of (v) (a) to -NCO groups in (v) (f) in the carbinol terminated silicone/polyurethane hybrid prepolymer based coating composition (v) is from 0.95:1 to 1.05:1; and a platinum group metal-based catalyst (v) (g). The carbinol terminated silicone/polyurethane hybrid prepolymer based coating composition is prepared for use in a silicone leather composite material.

Inventors

CHEN, YUSHENG
CHEN, Huangguan
CHEN, XI
WANG, RUI
CHEN, TINGTING
GUO, YI
SHI, QING

Assignees

Dow Silicones Corporation
Dow Global Technologies LLC

Dates

Publication Date: 20260506
Application Date: 20230628

Claims (16)

A method of preparing a carbinol terminated silicone/polyurethane hybrid prepolymer based coating composition comprising the steps of (A) Preparing a carbinol terminated silicone/polyurethane hybrid prepolymer by mixing together (I) A diisocyanate in an amount of 20 to 30 wt. %of the step (A) starting ingredients, (II) an alkane diol chain extender in an amount of from 5 to 15wt. %of the step (A) starting ingredients (III) a carbinol terminated polydimethylsiloxane in an amount of from 25 to 45wt. %of the step (A) starting ingredients (IV) a Solvent in an amount of from 20 to 40 wt. %of the step (A) starting ingredients, and optionally (V) a polyether triol in an amount of up to 2 wt. %of the step (A) starting ingredients wherein the molar ratio of OH: NCO is greater than 1.15 : 1; by gradually introducing a suitable catalyst while heating the mixture to a predetermined reaction temperature of from 60 to 90℃ and continuing to stir the mixture for a pre-determined time of at least 90 minutes whilst maintaining the mixture at the predetermined reaction temperature and then cooling the reaction product of carbinol terminated silicone/polyurethane hybrid prepolymer; and (B) preparing the carbinol terminated silicone/polyurethane hybrid prepolymer based coating composition (v) by mixing (v) (a) the carbinol terminated silicone/polyurethane hybrid prepolymer with (v) (b) optional cured silicone elastomer powder; (v) (c) optional silicon-free organic particles and/or microparticles selected from at least one of polymethyl methacrylate (PMMA) , ethylene-vinyl acetate copolymer (EVA) , ethylene-acrylate copolymer (EAA) , ethylene-butyl acrylate copolymer (EBA) , ethylene-methyl acrylate copolymer (EMA) , ethylene-ethyl acrylate copolymer (EEA) or polyurethane polymer; (v) (d) a polyorganosiloxane containing at least two or alternatively at least three silicon bonded hydrogen (-Si-H) groups per molecule present in an amount of from 1 wt. %-10 wt. %of the composition; (v) (f) a polyisocyanate crosslinker having three or more isocyanate groups per molecule in an amount such that the molar ratio of -OH groups of (v) (a) to -NCO groups in (v) (f) in the carbinol terminated silicone/polyurethane hybrid prepolymer based coating composition (v) is from 0.95 : 1 to 1.05 : 1; and (v) (g) a platinum group metal-based catalyst.
A method of preparing a carbinol terminated silicone/polyurethane hybrid prepolymer based coating composition wherein a polyurethane cure catalyst (v) (e) is also added into the carbinol terminated silicone/polyurethane hybrid prepolymer based coating composition.
A carbinol terminated silicone/polyurethane hybrid prepolymer based coating composition obtained or obtainable by the method of claim 1 or 2.
A carbinol terminated silicone/polyurethane hybrid prepolymer based coating composition (v) comprising (v) (a) the carbinol terminated silicone/polyurethane hybrid prepolymer with (v) (b) optional cured silicone elastomer powder; (v) (c) optional silicon-free organic particles and/or microparticles selected from at least one of polymethyl methacrylate (PMMA) , ethylene-vinyl acetate copolymer (EVA) , ethylene-acrylate copolymer (EAA) , ethylene-butyl acrylate copolymer (EBA) , ethylene-methyl acrylate copolymer (EMA) , ethylene-ethyl acrylate copolymer (EEA) or polyurethane polymer; (v) (d) a polyorganosiloxane containing at least two or alternatively at least three silicon bonded hydrogen (-Si-H) groups per molecule present in an amount of from 1 wt. %-10 wt. %of the composition; (v) (f) a polyisocyanate crosslinker having three or more isocyanate groups per molecule in an amount such that the molar ratio of -OH groups of (v) (a) to -NCO groups in (v) (f) in the carbinol terminated silicone/polyurethane hybrid prepolymer based coating composition (v) is from 0.95 : 1 to 1.05 : 1; and (v) (g) a platinum group metal-based catalyst.
A carbinol terminated silicone/polyurethane hybrid prepolymer based coating composition in accordance with claim 4 wherein the silicone/polyurethane hybrid prepolymer based coating composition additionally comprises a polyurethane cure catalyst (v) (e) .
A method of preparing a carbinol terminated silicone/polyurethane hybrid prepolymer by mixing together (I) a diisocyanate in an amount of 20 to 30 wt. %of the step (A) starting ingredients, (II) an alkane diol chain extender in an amount of from 5 to 15wt. %of the step (A) starting ingredients (III) a carbinol terminated polydimethylsiloxane in an amount of from 25 to 45wt. %of the step (A) starting ingredients (IV) a Solvent in an amount of from 20 to 40 wt. %of the step (A) starting ingredients, and optionally (V) a polyether triol in an amount of up to 2 wt. %of the step (A) starting ingredients wherein the molar ratio of OH: NCO is greater than 1.15 : 1; by gradually introducing a suitable catalyst while heating the mixture to a predetermined reaction temperature of from 60 to 90℃ and continuing to stir the mixture for a pre-determined time of at least 90 minutes whilst maintaining the mixture at the predetermined reaction temperature and then cooling the reaction product of carbinol terminated silicone/polyurethane hybrid prepolymer.
A carbinol terminated silicone/polyurethane hybrid prepolymer obtained or obtainable from the method of claim 6 herein.
Use of a carbinol terminated silicone/polyurethane hybrid prepolymer in accordance with claim 7 or as prepared in accordance with claim 6 in a carbinol terminated silicone/polyurethane hybrid prepolymer based coating composition.
A silicone leather composite material comprising (i) A textile support layer; (ii) A silicone binder, wherein the silicone binder is the cured product of a 2-part hydrosilylation curable silicone rubber composition designed to adhere to the textile support layer (i) and the skin layer (iii) , which has a shore A hardness of from 20 to 40 measured in accordance with ASTM D2240; (iii) A silicone skin layer, wherein the silicone skin layer is the cured product of a 2-part hydrosilylation curable silicone rubber composition comprising an adhesion promoter, which silicone skin layer has a shore A hardness greater than or equal to (≥) 50 when measured in accordance with ASTM D2240; (iv) a silicone topcoat layer wherein the silicone topcoat layer is the cured product of a 2-part hydrosilylation curable silicone topcoat which comprises an adhesion promoter; and (v) a silicone/polyurethane hybrid prepolymer based coating layer which is the cured product of the silicone/polyurethane hybrid prepolymer based coating composition in accordance with claim 3, 4 or 5; wherein the silicone binder (ii) is adhered between textile support (i) and the skin layer (iii) , the skin layer (iii) is between the silicone binder layer (ii) and the silicone/polyurethane hybrid prepolymer based coating layer and silicone topcoat layer (iv) is on the silicone/polyurethane hybrid prepolymer based coating layer (v) .
A silicone leather composite material in accordance with claim 9 wherein the average dry coat thickness of the carbinol terminated silicone/polyurethane hybrid prepolymer based coating layer (v) is between 10 μm to 50 μm using the method disclosed in the description.
A silicone leather composite material in accordance with claim 9 or 10 wherein the silicone/polyurethane hybrid prepolymer based coating layer (v) has a modulus equal to or greater than 10 MPa determined in accordance with ASTM D882, using the initial linear portion of the load-extension curve to calculate the modulus, is provided in the silicone leather composite material between the silicone skin layer (iii) and the silicone topcoat layer (iv) .
A silicone leather composite material in accordance with claim 9, 10 or 11 which can withstand a Gakushin abrasion resistance of at least 5000 cycles as measured using the method in the description.
A method of preparing the silicone leather composite material in accordance with claim 9 comprising the steps of preparing a carbinol terminated silicone/polyurethane hybrid prepolymer based coating composition in accordance with claim 1 or 2 and then (a) coating a release paper with a layer of the carbinol terminated silicone/polyurethane hybrid prepolymer based coating composition and curing said composition to provide a carbinol terminated silicone/polyurethane hybrid prepolymer based coating layer (v) ; (b) Applying a layer of a silicone skin composition on to the cured carbinol terminated silicone/polyurethane hybrid prepolymer based coating layer (v) and curing said composition to provide a silicone skin layer (iii) ; (c) Applying a layer of silicone binder composition onto cured silicone skin layer (iii) and applying a textile layer (i) onto the silicone binder composition and curing and/or laminating said composition to form a silicone binder layer (ii) between said textile support layer (i) and said skin layer (iii) ; (d) Removing the release paper from the cured carbinol terminated silicone/polyurethane hybrid prepolymer based coating layer (v) ; and (e) Applying a layer of a 2-part hydrosilylation curable silicone topcoat composition onto the cured carbinol terminated silicone/polyurethane hybrid prepolymer based coating layer (v) and curing said topcoat composition to form a silicone topcoat layer (iv) .
A method in accordance with claim 13 wherein the silicone/polyurethane hybrid prepolymer based coating composition is cured at a temperature of from 120 ℃ to 180 ℃ for 2-10 minutes, to obtain an average dry coat thickness of from 10 μm to 50 μm using the method described herein.
A method in accordance with claim 13 or 14 wherein the 2-part hydrosilylation curable silicone topcoat composition is cured at a temperature of from at 130 ℃-160 ℃ for 2-8 minutes to form a silicone topcoat (v) having an average dry coat thickness of from 5-20 μm using the method disclosed in the description.
Use of a layer of a carbinol terminated silicone/polyurethane hybrid prepolymer based coating layer (v) in a silicone/polyurethane composite leather material in accordance with any one of claims 9 to 12 or prepared in accordance with the method of claims 13 to 15 in or for furniture, decoration, handbags, binders, luggage, garments, phone covers, covers for electronic goods, book covers, footwear, car interiors, car seats, wearable devices and/or medical beds/seats.

Description

SILICONE LEATHER COATING COMPOSITION The present disclosure relates to a method for preparing a carbinol terminated silicone/polyurethane hybrid prepolymer based coating composition (v) comprising the steps of (A) Preparing a carbinol terminated silicone/polyurethane hybrid prepolymer; and (B) preparing the carbinol terminated silicone/polyurethane hybrid prepolymer based coating composition (v) by mixing the carbinol terminated silicone/polyurethane hybrid prepolymer produced in (A) (component (v) (a) ) with optional cured silicone elastomer powder (v) (b) ; optional silicon-free organic particles and/or microparticles (v) (c) ; a polyorganosiloxane containing at least two or alternatively at least three silicon bonded hydrogen (-Si-H) groups per molecule (v) (d) ; a polyisocyanate crosslinker having three or more isocyanate groups per molecule (v) (f) in an amount such that the molar ratio of -OH groups of (v) (a) to -NCO groups in (v) (f) in the carbinol terminated silicone/polyurethane hybrid prepolymer based coating composition (v) is from 0.95 : 1 to 1.05 : 1; and a platinum group metal-based catalyst (v) (g) . The carbinol terminated silicone/polyurethane hybrid prepolymer based coating composition is prepared for use in a silicone leather composite material. A variety of synthetic alternatives to natural leather have been developed with polyurethane (PU) or polyvinylchloride (PVC) based materials having been mainly used. They are used in a wide variety of applications including for furniture, decoration, handbags, luggage, garments, footwear, car interiors, car seats and the like. However, to meet increasingly strict safety regulations, to be utilised as synthetic leather, they need to meet stringent physical property requirements, regarding e.g., flame retardancy, smoke density, suitable adhesion strength in order to prevent a coating layer to be peeled off at the time of usage, heat resistance, contamination resistance, solvent resistance, hydrolysis resistance, and the like, are required. Often the PU and/or PVC based materials cannot satisfy one or more of the above-mentioned physical property requirements. Silicone-based leather composite materials provide further synthetic alternatives to natural leather. Such silicone-based leather composite materials can have several advantages over the PU and/or PVC based synthetic leather materials discussed above. For example, they can be prepared using more eco-friendly production methods, using no plasticizer (s) , toxic heavy metal (s) or environmentally problematic solvents such as dimethylformamide (DMF) which often remain, at least partially, in the synthetic PU and/or PVC leather products post manufacture. Silicone-based leather composite materials may be made via several routes but are generally manufactured using a textile support layer and two or more layers of hydrosilylation curable liquid silicone rubber compositions and a release paper. For example, a first liquid silicone rubber (LSR) composition may be coated onto a release paper and is then cured to form a first or skin layer. A second LSR composition, usually having different physical properties to that of the first, is adhered to the cured first layer to form an adhesion layer and a textile support layer is adhered to the second LSR layer prior to cure, after which the second LSR composition is cured to form a binder layer situated between the skin layer and the textile support layer. One or more additional layers of hydrosilylation curable silicone elastomer compositions may also be applied between the release paper and the textile layer as deemed appropriate to form a silicone-based leather composite material. For example, a third layer may be provided as a protective topcoat on top of the skin layer. The release paper is subsequently removed as and when required. Such silicone-based leather composite materials are able to outperform conventional PU and PVC synthetic leather, from a physical property perspective because of the ability to provide, for example, better flexibility over a broad temperature range as well as excellent UV resistance, thermal resistance and flame retardancy. Topcoats are particularly important as they help to provide advantageous properties such as soil resistance as well as being both kind to the human skin and providing an excellent hand-feeling for users. However, due to intrinsically weak intermolecular interaction between polysiloxane chains, silicone offerings suffer from poor mechanical strength and thus poor abrasion resistance. Therefore, the use of silicone leather composite materials tends to be limited to application scenarios with low abrasion resistant requirements, whilst PU and PVC synthetic leathers are often used in applications requiring good anti-abrasion resistance, such as in automotive interiors. There remains a need therefore to provide silicone leather composite materials with improved abrasion resistance, whilst retaining t