Method for modifying polyurethane by addition type liquid silicone rubber

Abstract

The invention provides a preparation method of a polyurethane-addition type liquid silicone rubber material, which is characterized in that the surface of a polyurethane material is chemically modified, so that addition type liquid silicone rubber is cured and bonded on the surface of the polyurethane material. The method comprises the following steps: (i) surface modification of polyurethane; and (ii) preparing and curing the addition type silicone rubber coating. According to the technology, bonding of the polyurethane material and the addition type liquid silicone rubber is achieved through chemical bonding, so that the two materials have stable and good bonding performance, and the method can be widely applied to the fields of medical instruments, textiles, buildings and the like.

Description

Technical Field

[0001] The invention relates to the field of polymer materials, and in particular to a method for bonding polyurethane to addition-type liquid silicone rubber. Background Art

[0002] Polyurethane (PU) is a polymer material with excellent mechanical properties and good biocompatibility. It has a structure of alternating soft and hard segments and is formed by step-by-step polymerization of isocyanate and polyol. It is widely used in the medical field, especially in implantable devices such as artificial blood vessels, heart valves, and prosthetic tissue materials. However, the disadvantage of polyurethane is that it has poor biostability and can degrade and calcify in the human body. In practical applications, it is usually prepared into a composite material or grafted with other polymer materials to make up for its defects. Addition-type liquid silicone rubber is a material that overcomes the degradation of polyurethane materials. It is an elastomer formed by cross-linking the carbon-carbon double bonds in vinyl silicone oil and the silicon-hydrogen bonds in hydrogen-containing silicone oil under the action of Pt catalyst. It has excellent stability and biocompatibility. However, due to the low surface energy of silicone rubber, it is difficult to form good compatibility and adhesion with polyurethane, which is challenging.

[0003] Modification of polyurethane is an effective way. The modification of polyurethane can be roughly divided into the following two ways: bulk modification and surface modification of polyurethane. Patent CN101798375A introduces polysiloxane segments modified with organic functional groups in the synthesis process of polyurethane to enhance its adhesion to silicone rubber, overcoming the disadvantage that the previous prepolymer cannot adhere to the surface of addition-type silicone rubber; Patent CN114395246B discloses a dynamically vulcanized silicone modified polyurethane and its preparation method. The vinyl side groups in the butyl hydroxy polyurethane of the vinyl side group undergo silylation addition with hydrogen-containing silicone oil, and the obtained butyl hydroxy polyurethane grafted with hydrogen-containing silicone oil undergoes cross-linking reaction with vinyl silicone rubber to obtain vulcanized vinyl silicone rubber particles containing butyl hydroxy polyurethane segments, which greatly improves the compatibility of silicone in polyurethane. The research focus of the above bulk modification is to introduce siloxane segments into the polyurethane segments starting from isocyanate monomers to enhance the compatibility of polyurethane and silicone rubber, but no further research has been done on the technology of bonding silicone rubber materials to molded polyurethane materials. By consulting relevant literature, surface modification of polyurethane can effectively enhance its adhesion to silicone rubber. For example, Wang Jing et al. used terminal isocyanate triethoxysilane as a coupling agent to modify the surface of polyurethane, and the ethoxy group in the cross-linking agent participated in the polycondensation reaction of silicone rubber, which effectively improved the adhesion between silicone rubber and polyurethane. Wang et al. used diisocyanate [4,4'-methylene diphenyl diisocyanate (MDI)] as a spacer to graft vinyl and Si-H groups to improve the adhesion between silicone rubber and polyurethane surface. At present, there is a lack of technology and research on the adhesion between polyurethane and silicone rubber, but the combination of the two materials has obvious advantages and a wide range of applications, and relevant technologies are urgently needed. Summary of the invention

[0004] The present invention aims to improve the adhesion between polyurethane and addition-type liquid silicone rubber by chemical grafting. The method makes the polyurethane and addition-type liquid silicone rubber coating have good adhesion, and the method does not affect the mechanical properties of the two materials themselves, and can be widely used in the fields of medical equipment, textiles, automobile assembly, etc.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions: A method for modifying polyurethane with addition-type liquid silicone rubber comprises the following two steps: S1: polyurethane is surface-modified by isocyanate groups to obtain modified polyurethane; S2: Apply the addition type liquid silicone rubber coating to the surface of the modified polyurethane, and obtain the modified polyurethane after curing. The surface modification of polyurethane by isocyanate group is to place the polyurethane material in a mixed aqueous solution containing isocyanate modifier and oxidant, under nitrogen protection, the reaction temperature is 60~100℃, the reaction time is 0.2~2h; after the reaction is completed, the surface of the polyurethane material is cleaned with ultrapure water, and the modified polyurethane material is obtained after vacuum drying.

[0006] The isocyanate-containing modifier includes one or more of isocyanoethyl methacrylate, 2-isocyanoethyl acrylate, and 1,1-bis(acryloyloxymethyl)ethyl isocyanate.

[0007] The oxidant is a persulfate, and the persulfate includes one or more of potassium persulfate, sodium persulfate, and ammonium persulfate. The concentration of the oxidant is 2-20wt%, and the concentration of the modifier is 0.5-8wt%.

[0008] The surface modification process of the polyurethane material is schematically shown as follows (taking isocyanoethyl methacrylate as an example):

[0009] The oxidant in the composite solvent plays a role in hydroxylation of the polyurethane surface during the modification process; it combines with the hydroxyl groups on the polyurethane surface during the reaction to form chemical bonds.

[0010] The addition type liquid silicone rubber coating compound is an elastomer formed by a base rubber obtained by vacuum kneading vinyl silicone oil and fumed silica, to which hydrogen-containing silicone oil is added as a cross-linking agent, and a hydrosilylation reaction is carried out through a platinum catalyst and an inhibitor.

[0011] The components and weight proportions of each raw material in the addition type liquid silicone rubber coating compound are as follows: 80-100 parts of vinyl silicone oil 5-50 parts of structure-modified fumed silica 2-20 parts of hydrogen silicone oil Ethylene cyclohexanol 0.05-0.1 parts Pt catalyst 0.01-0.1 parts.

[0012] The addition type liquid silicone rubber compound is applied to the surface of the modified polyurethane film, placed at 80-100° C., and cured for 5-20 minutes to obtain a tightly bonded polyurethane-addition type liquid silicone rubber material.

[0013] The key technical feature of the present invention is to provide a surface modification method for polyurethane materials, by grafting carbon-carbon double bonds on the polyurethane surface and generating strong chemical bonds using the principle of silicon-hydrogen addition reaction, thereby achieving close adhesion between the addition-type liquid silicone rubber coating and the polyurethane material.

[0014] The technology provided by the present invention is used to achieve effective bonding between the addition type liquid silicone rubber coating and the polyurethane material. The problem of the lack of existing bonding technology and weak bonding is solved, and the bonding performance of the addition type liquid silicone rubber and the polyurethane material is greatly improved. The method has a wide range of applications, is easy to operate, and does not change the mechanical properties of the material. DETAILED DESCRIPTION

[0015] Example 1 Prepare a 5wt% potassium persulfate aqueous solution, add the modifier isocyanoethyl methacrylate to the solution to make the modifier concentration 2wt%, and purge the solution with nitrogen. Place the polyurethane film in the mixed solution, keep the temperature at 80℃ under immersion conditions, and react for 40min. After the reaction is completed, take out the film, rinse it with ultrapure water, and vacuum dry it for 8h to obtain a modified polyurethane film.

[0016] Weigh 100 parts of 20000mPa·s vinyl silicone oil, add 20 parts of structure-modified fumed silica in batches, knead for 30 minutes, heat to 150°C, and knead for 3 hours. Turn on the vacuum pump, vacuum knead for 2 hours, turn off the vacuum and heat, and wait for the material to cool to room temperature to obtain the base rubber; weigh 20g of the base rubber in a blender, add 0.1 parts of ethynyl cyclohexanol and 12 parts of hydrogenated silicone oil, heat and stir at 40°C for 20 minutes, add 0.05 parts of chloroplatinic acid, and continue stirring for 30 minutes to obtain the liquid silicone rubber compound; The addition type liquid silicone rubber compound was applied to the surface of the modified polyurethane film and placed in a 100°C forced air drying oven for 20 minutes. After the silicone rubber was completely cured, the shear strength and 180° peel strength tests were performed on the obtained material.

[0017] Example 2 Prepare a 5wt% potassium persulfate aqueous solution, add the modifier 2-isocyanatoethyl acrylate to the solution to make the modifier concentration 2wt%, and purge the solution with nitrogen. Place a piece of polyurethane film in the mixed solution, keep the temperature at 80°C under immersion conditions, and react for 40 minutes. After the reaction is completed, take out the film, rinse it with ultrapure water, and vacuum dry it for 8 hours to obtain a modified polyurethane film.

[0018] Weigh 100 parts of 20000mPa·s vinyl silicone oil, add 20 parts of structure-modified fumed silica in batches, knead for 30 minutes, heat to 150°C, and knead for 3 hours. Turn on the vacuum pump, vacuum knead for 2 hours, turn off the vacuum and heat, and wait for the material to cool to room temperature to obtain the base rubber; weigh 20g of the base rubber in a blender, add 0.1 parts of ethynyl cyclohexanol and 12 parts of hydrogenated silicone oil, heat and stir at 40°C for 20 minutes, add 0.05 parts of chloroplatinic acid, and continue stirring for 30 minutes to obtain the liquid silicone rubber compound; The addition type liquid silicone rubber compound was applied to the surface of the modified polyurethane film and placed in a 100°C forced air drying oven for 20 minutes. After the silicone rubber was completely cured, the shear strength and 180° peel strength tests were performed on the obtained material.

[0019] Example 3 Prepare a 10wt% potassium persulfate aqueous solution, add the modifier isocyanoethyl methacrylate to the solution to make the modifier concentration 4wt%, and purge the solution with nitrogen. Place a piece of polyurethane film in the mixed solution, keep the temperature at 80℃, and react for 40min. After the reaction is completed, take out the film, rinse it with ultrapure water, and vacuum dry it for 8h to obtain a modified polyurethane film.

[0020] Weigh 100 parts of 20000mPa·s vinyl silicone oil, add 20 parts of structure-modified fumed silica in batches, knead for 30 minutes, heat to 150°C, and knead for 3 hours. Turn on the vacuum pump, vacuum knead for 2 hours, turn off the vacuum and heat, and wait for the material to cool to room temperature to obtain the base rubber; weigh 20g of the base rubber in a blender, add 0.1 parts of ethynyl cyclohexanol and 12 parts of hydrogenated silicone oil, heat and stir at 40°C for 20 minutes, add 0.05 parts of chloroplatinic acid, and continue stirring for 30 minutes to obtain the liquid silicone rubber compound; The addition type liquid silicone rubber compound was applied to the surface of the modified polyurethane film and placed in a 100°C forced air drying oven for 20 minutes. After the silicone rubber was completely cured, the shear strength and 180° peel strength tests were performed on the obtained material.

[0021] Example 4 Prepare a 15wt% potassium persulfate aqueous solution, add the modifier isocyanoethyl methacrylate to the solution to make the modifier concentration 6wt%, and purge the solution with nitrogen. Place a piece of polyurethane film in the mixed solution, immerse it under the condition of keeping the temperature at 80℃ and react for 40min. After the reaction is completed, take out the film, rinse it with ultrapure water, and vacuum dry it for 8h to obtain a modified polyurethane film.

[0022] Weigh 100 parts of 20000mPa·s vinyl silicone oil, add 20 parts of structure-modified fumed silica in batches, knead for 30 minutes, heat to 150°C, and knead for 3 hours. Turn on the vacuum pump, vacuum knead for 2 hours, turn off the vacuum and heat, and wait for the material to cool to room temperature to obtain the base rubber; weigh 20g of the base rubber in a blender, add 0.1 parts of ethynyl cyclohexanol and 12 parts of hydrogenated silicone oil, heat and stir at 40°C for 20 minutes, add 0.05 parts of chloroplatinic acid, and continue stirring for 30 minutes to obtain the liquid silicone rubber compound; The addition type liquid silicone rubber compound was applied to the surface of the modified polyurethane film and placed in a 100°C forced air drying oven for 20 minutes. After the silicone rubber was completely cured, the shear strength and 180° peel strength tests were performed on the obtained material.

[0023] Comparative Example 1 Take a piece of polyurethane film, clean it with toluene, and dry it in a vacuum drying oven for 24 hours.

[0024] Weigh 100 parts of 20000mPa·s vinyl silicone oil, add 20 parts of structure-modified fumed silica in batches, knead for 30 minutes, heat to 150°C, and knead for 3 hours. Turn on the vacuum pump, vacuum knead for 2 hours, turn off the vacuum and heat, and wait for the material to cool to room temperature to obtain the base rubber; weigh 20g of the base rubber in a blender, add 0.1 parts of acetylene alcohol inhibitor and 12 parts of hydrogen-containing silicone oil, heat and stir at 40°C for 20 minutes, add 0.05 parts of Pt catalyst, and continue stirring for 30 minutes to obtain the liquid silicone rubber compound; The addition type liquid silicone rubber compound was applied to the surface of the modified polyurethane film and placed in a 100°C forced air drying oven for 20 minutes. After the silicone rubber was completely cured, the shear strength and 180° peel strength tests were performed on the obtained material.

[0025] Table 1 Shear strength and 180° peel strength test

[0026] As shown in Table 1, the shear strength and 180° peel strength tests were performed on the adhesive materials obtained in Examples 1 to 4 and Comparative Example 1. The test results show that the surface modification technology of the polyurethane material provided by the present invention can effectively improve the adhesion between polyurethane and addition-type liquid silicone rubber.

Claims

1. A method for preparing a polyurethane-addition type liquid silicone rubber material, characterized in that: It includes the following two steps: S1: polyurethane is surface-modified by isocyanate groups to obtain modified polyurethane; S2: applying the addition type liquid silicone rubber coating material to the modified polyurethane surface, and obtaining the polyurethane-addition type liquid silicone rubber material after curing.

2. The method for preparing the polyurethane-addition type liquid silicone rubber material according to claim 1, characterized in that: The surface modification of polyurethane with isocyanate group is to place the polyurethane material in a mixed aqueous solution containing isocyanate modifier and oxidant, under nitrogen protection, reaction temperature 60~100℃, reaction time 0.2~2h; after the reaction is completed, the surface of the polyurethane material is cleaned with ultrapure water, and vacuum dried to obtain the modified polyurethane material.

3. The method for preparing the polyurethane-addition type liquid silicone rubber material according to claim 1, characterized in that: The isocyanate-containing modifier includes one or more of isocyanoethyl methacrylate, 2-isocyanoethyl acrylate, and 1,1-bis(acryloyloxymethyl)ethyl isocyanate.

4. The method for preparing the polyurethane-addition type liquid silicone rubber material according to claim 3, characterized in that: The oxidant is a persulfate, and the persulfate includes one or more of potassium persulfate, sodium persulfate, and ammonium persulfate.

5. The method for preparing the polyurethane-addition type liquid silicone rubber material according to claim 4, characterized in that: The concentration of the oxidant is 2~20wt%, and the concentration of the modifier is 0.5~8wt%.

6. The method for preparing the polyurethane-addition type liquid silicone rubber material according to claim 1, characterized in that: The addition type liquid silicone rubber coating compound is an elastomer formed by a base rubber obtained by vacuum kneading vinyl silicone oil and fumed silica, to which hydrogen-containing silicone oil is added as a cross-linking agent, and a hydrosilylation reaction is carried out through a platinum catalyst and an inhibitor.

7. The method for preparing the polyurethane-addition type liquid silicone rubber material according to claim 6, characterized in that: The components and weight proportions of each raw material in the addition type liquid silicone rubber coating compound are as follows: 80-100 parts of vinyl silicone oil 5-50 parts of structure-modified fumed silica 2-20 parts of hydrogen silicone oil Ethylene cyclohexanol 0.05-0.1 parts Pt catalyst 0.01-0.1 parts.

8. The method for preparing the polyurethane-addition type liquid silicone rubber material according to claim 1, characterized in that: The method comprises applying an addition type liquid silicone rubber compound to the surface of a modified polyurethane film, placing the compound at 80-100° C., and curing the compound for 5-20 minutes to obtain a polyurethane-addition type liquid silicone rubber material.

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