Elastic flame-retardant coating for rubber and preparation method of elastic flame-retardant coating

Abstract

The invention discloses an elastic flame-retardant coating for rubber. The elastic flame-retardant coating is mainly composed of a component A and a component B according to a mass ratio of 3: 1-5: 1, the component A is composed of polycarbonate resin, an additive flame retardant, mica powder, titanium dioxide, an antirust filler, a dispersant, a leveling agent, a defoaming agent, a catalyst, a mixed solvent and the like; and the component B is composed of a flame-retardant elastic prepolymer and an NCO-containing silane coupling agent, wherein the flame-retardant elastic prepolymer is formed by carrying out addition polymerization on two or more of polyester diol with different molecular weights and side chains containing phosphorus, polycaprolactone diol with different molecular weights and trimethylolpropane, 4, 4 '-dicyclohexylmethane diisocyanate, a catalyst and a solvent. The elastic flame-retardant coating for the rubber has excellent flame-retardant performance and elastic performance, has excellent adhesive force and elastic matching performance with various rubbers, and can promote the large-scale use of the rubbers in the industries of high-speed rails, ships and buildings.

Description

Technical Field

[0001] The invention belongs to the technical field of fine chemical coating materials and applications, and particularly relates to an elastic flame-retardant coating for rubber and a preparation method thereof. Background Art

[0002] Rubber refers to a highly elastic polymer material with reversible deformation. It is elastic at room temperature and can produce large deformation under very small external force. It can return to its original shape after the external force is removed. Rubber is a completely amorphous polymer with a low glass transition temperature (Tg) and a large molecular weight. Rubber is divided into two types: natural rubber and synthetic rubber. Natural rubber is processed by extracting gum from plants such as rubber trees and rubber grass; synthetic rubber is obtained by polymerization of various monomers. Rubber products are widely used in industry and life.

[0003] With the rapid development of economy and the continuous improvement of people's living standards, high-speed rail, shipbuilding and construction industries are also developing by leaps and bounds. In order to reduce the noise and vibration generated by the operation of high-speed rail, rubber products such as air springs and other elastic elements are widely used; ship cabins, hull accessories (windows, hatches and doors), etc. will use a large number of marine rubber seals, shock absorbers, etc.; modern buildings, rubber is even more useful, such as glass window sealing rubber strips, sound insulation floors, sound-absorbing sponges, rubber carpets and rainproof materials used in buildings. These elastic elements are usually made of polyisoprene rubber, natural rubber or chloroprene rubber. Because they are flammable (oxygen index is 19% to 20%), once a fire occurs, it will seriously endanger the safety of transportation equipment and buildings. In particular, this type of rubber product is also prone to release a large amount of toxic and harmful smoke, which greatly reduces the probability of safe escape and evacuation of personnel. Therefore, the flame retardancy of rubber products has become an important research topic in the fields of rail transportation, ship transportation and construction. At present, there are two ways to solve the flame retardancy of rubber: one is to add flame retardants to rubber to make the rubber body flame retardant; the other is to apply rubber flame retardant coating on the surface of rubber.

[0004] The existing technical solutions for rubber flame retardancy are:

[0005] (1) The flame retardant of the rubber body. In the prior art, a large amount of halogenated phosphorus flame retardant and magnesium hydroxide / aluminum hydroxide are often added to the body to achieve the desired flame retardant effect. The use of halogenated flame retardants is harmful to the human body and the environment, and the addition of such a high content of flame retardants will also cause the elastic rubber material to lose key properties, such as fatigue resistance and damping properties.

[0006] (2) Rubber flame retardant coating: Rubber flame retardant coating is a novel method with the characteristics of simple operation and low cost, and can retain more than 80% of the damping performance and anti-fatigue performance of rubber. However, the flame retardant coating that can be applied to the rubber surface currently has poor flame retardant performance and elastic matching with rubber.

[0007] Existing technical solutions for rubber flame retardancy have the following defects:

[0008] (1) The flame retardant of the rubber body is due to the addition of a large amount of flame retardants, and the anti-fatigue performance and damping characteristics of the rubber are poor;

[0009] (2) In order to meet the requirement that the oxygen index of the rubber flame retardant coating is greater than 28%, a large amount of flame retardant (ammonium polyphosphate and pentaerythritol in combination) needs to be added. The maximum elongation at break of the flame retardant coating is 150%, which has poor compatibility with the elasticity of the rubber (the elongation at break of the rubber is greater than 250%). Summary of the invention

[0010] The main purpose of the present invention is to directly add additive flame retardants to existing elastic flame retardant coatings, which will affect the mechanical properties of the elastic coatings, thereby losing the protective effect of the elastic flame retardant coatings on rubber.

[0011] A rubber elastic flame retardant coating is composed of component A and component B in a mass ratio of 3:1 to 5:1, wherein component A is composed of the following components in mass percentage:

[0012]

[0013] Component B consists of the following components by mass percentage:

[0014] Flame retardant elastic prepolymer 90%~95%

[0015] Contains 5% to 10% NCO silane coupling agent

[0016] Furthermore, the flame-retardant elastic prepolymer is prepared by addition polymerization of two or more of polyester diols with side chains containing phosphorus of different molecular weights, polycaprolactone diols with side chains containing phosphorus of different molecular weights, and trimethylolpropane with 4,4'-dicyclohexylmethane diisocyanate, a catalyst and a solvent, with the NCO percentage content being the final indicator and the NCO percentage content being controlled at 8% to 10%.

[0017] Furthermore, the polycarbonate resin is at least one of UBE's UH-50, PH-50, UM-90, and Tosoh's PCP-100L2.

[0018] Furthermore, the additive flame retardant is selected from at least one of ammonium polyphosphate, aluminum hydroxide, magnesium hydroxide, and pentaerythritol.

[0019] Furthermore, the mica powder is at least one of GA-2, GA-4 and GD-2 with different particle sizes.

[0020] Furthermore, the anti-rust filler is at least one of aluminum tripolyphosphate and zinc phosphate.

[0021] Furthermore, the dispersant is at least one of YCK-2040, YCK-2050 and YCK-2070.

[0022] Furthermore, the leveling agent is at least one of YCK-1010, YCK-1020 and YCK-1030.

[0023] Furthermore, the defoaming agent is at least one of YCK-615, YCK-620 and YCK-610.

[0024] Furthermore, the catalyst is at least one of dibutyltin dilaurate, monobutyltin oxide, and stannous chloride.

[0025] Furthermore, the mixed solvent is at least one of xylene, butanone, cyclohexanone and butyl acetate.

[0026] Furthermore, the NCO-containing silane coupling agent is at least one of SCA-Y25M, SCA-Y25Y and SCA-Y25E.

[0027] In a second aspect, the present invention also provides a method for preparing an elastic flame retardant coating for rubber, wherein the materials are prepared according to the above-mentioned formula.

[0028] The preparation process of its component A is:

[0029] Add polycarbonate resin, dispersant, leveling agent, defoamer, catalyst and mixed solvent to the pull cylinder in sequence under stirring, add additive flame retardant, mica powder, titanium dioxide and anti-rust filler under stirring, grind to a fineness of less than 30 μm in a basket sand mill after stirring, filter the material to obtain component A;

[0030] The preparation process of component B is:

[0031] First, a mixture of two or more of polycaprolactone diols with different molecular weights and phosphorus-containing side chains, polyester diols with different molecular weights and phosphorus-containing side chains, and trimethylolpropane and a solvent are added to a reaction bottle filled with nitrogen, and the mixture is heated, refluxed, dehydrated, and then discharged to obtain a solution containing a hydroxyl resin; then, 4,4'-dicyclohexylmethane diisocyanate (HMDI) and a catalyst are added to another reaction bottle filled with nitrogen for primer preparation, and then the refluxed and dehydrated solution containing a hydroxyl resin is added dropwise to the reaction bottle, and the mixture is heated at 70° C. and 90° C. for gradient reaction, and the NCO percentage content is used as the final control index, and the material is filtered to obtain a flame-retardant elastic prepolymer; finally, the flame-retardant elastic prepolymer and the NCO silane coupling agent are evenly mixed according to a proportion, and the material is filtered to obtain component B;

[0032] The component A and component B prepared above are mixed according to a proportion and stirred evenly to obtain an elastic flame-retardant coating for rubber.

[0033] When synthesizing the elastic prepolymer curing agent, two or more of the following are selected: polyester diols with phosphorus in the side chain, polycaprolactone diols with phosphorus in the side chain of different molecular weights, and trimethylolpropane. This can improve the intrinsic flame retardant properties of the elastic coating without affecting the elastic matching between the coating and the rubber substrate. At the same time, the independently synthesized elastic prepolymer curing agent can be combined with the rubber elasticity to synthesize and adjust the soft and hard segments, thereby further satisfying the elastic matching with the rubber.

[0034] Difunctional and trifunctional polycarbonate resins are selected in component A of the elastic flame retardant coating, which can provide adjustment space for the reaction activity and film strength of the rubber flame retardant coating; at the same time, the additive flame retardant filler in component A uses a variety of flame retardants such as ammonium polyphosphate, pentaerythritol, aluminum hydroxide and magnesium hydroxide to provide guarantee for the flame retardant properties of the rubber flame retardant coating.

[0035] Beneficial Effects

[0036] (1) The elastic flame-retardant coating for rubber prepared by the present invention has a combustion oxygen index of 28% to 30%, and has good flame retardant properties.

[0037] (2) The elongation at break of the elastic flame retardant coating for rubber is greater than 300%, and the tensile strength is greater than 10 MPa, which meets the elastic matching of rubber. At the same time, after the elastic flame retardant coating is sprayed on the surface of polyisoprene rubber, natural rubber and chloroprene rubber to form a film, the cross-cut adhesion is ≤ Level 1, and the peel strength is ≥ 2 kN / m.

[0038] (3) Rubber elastic flame retardant coatings can improve and enhance the flame retardancy, oil resistance, aging resistance, wear resistance (friction loss ≤10mg using CS-10 grinding wheel at 500g / 1000r) and high and low temperature resistance (-55℃~135℃) of rubber products without affecting the performance of rubber products, thus broadening the use areas and application prospects of rubber and extending the service life of rubber products.

[0039] (4) It has excellent flame retardant and elastic properties, and has excellent adhesion and elastic matching properties with a variety of rubbers, which can promote the large-scale use of rubber in high-speed rail, shipbuilding and construction industries. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Polycarbonate resins with different molecular weights, different additive flame retardants, and various additives (leveling agents, defoamers, dispersants, and catalysts) in component A of the rubber flame retardant coating will be recombined; polycaprolactone resins with different molecular weights and different NCO silane coupling agents in component B will be recombined. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] Embodiment 1:

[0042] Preparation of component A of elastic flame-retardant coating for rubber: 12KgUH-50 polycarbonate resin and 9KgPCP-100L2 polycarbonate resin, 2.5KgYCK-2050 dispersant, 0.2KgYCK-1020 leveling agent, 0.5KgYCK-610 defoamer, 0.25Kg dibutyltin dilaurate, 14Kg xylene and 15Kg butyl acetate are added to the pull cylinder in sequence under stirring, and 14.25Kg ammonium polyphosphate, 4.75Kg pentaerythritol, 9KgGA-2 mica powder, 7Kg titanium dioxide, 8Kg aluminum tripolyphosphate and 2Kg zinc phosphate are added under stirring, and the mixture is ground with a basket sand mill to a fineness of less than 30μm after stirring. The material is filtered to obtain component A.

[0043] Preparation of component B of elastic flame retardant coating for rubber: First, add 20Kg of 1000 molecular weight side chain phosphorus-containing polycaprolactone diol, 5.1Kg side chain phosphorus-containing polyester diol (phosphorus content weight percentage greater than 12%), 3.57Kg trimethylolpropane and 13.41Kg xylene in a reaction bottle filled with nitrogen, heat and reflux for dehydration for 2h, then cool and discharge (hydroxy resin solution), then add 41.92Kg in another reaction bottle filled with nitrogen. 4,4'-dicyclohexylmethane diisocyanate (HMDI) and 0.02 kg of stannous octoate are used for primer, and then the above-mentioned reflux dehydrated hydroxyl resin solution is added dropwise into the reaction bottle, and the reaction is kept at 70°C for 2 hours and 90°C for 4 to 5 hours. The NCO percentage is measured to be 8% to 10%. The material is cooled and filtered to obtain a flame-retardant elastic prepolymer. Finally, 84 kg of the above-prepared flame-retardant elastic prepolymer is evenly mixed with 4.42 kg of SCA-Y25Y, and the material is filtered to obtain component B.

[0044] The mass ratio of component A and component B of the elastic flame retardant coating for rubber is 4:1, and they are mixed and stirred evenly.

[0045] Embodiment 2:

[0046] Preparation of component A of elastic flame-retardant coating for rubber: add 10KgUM-90 polycarbonate resin and 11KgPCP-100L2 polycarbonate resin, 2KgYCK-2070 dispersant, 0.2KgYCK-1020 leveling agent, 0.4KgYCK-620 defoamer, 0.3Kg monobutyl tin oxide, 10Kg xylene, 10Kg butyl acetate and 10Kg cyclohexanone into the pull cylinder in sequence under stirring, stir evenly and then add 10Kg aluminum hydroxide, 9Kg magnesium hydroxide, 9KgGA-2 mica powder, 7Kg titanium dioxide, 8Kg aluminum tripolyphosphate and 2Kg zinc phosphate under stirring, stir evenly and grind with a basket sand mill to a fineness of less than 30μm, filter the material to obtain component A.

[0047] Preparation of component B of elastic flame retardant coating for rubber: First, add 15Kg of polycaprolactone diols with a molecular weight of 1000 and 5Kg of polycaprolactone diols with a molecular weight of 2000 containing phosphorus in the side chain, 5.1Kg of polyester diols with a phosphorus content in the side chain (the weight percentage of phosphorus content is greater than 12%), 3.35Kg of trimethylolpropane and 11Kg of xylene in a reaction bottle filled with nitrogen, heat and reflux for dehydration for 2h, then cool and discharge (hydroxy resin solution), then add 39.3Kg of 4,4'-dicyclohexylmethane diisocyanate (HMDI) and 0.02 kg of stannous octoate are used for primer, and then the refluxed and dehydrated hydroxy resin solution is added dropwise into the reaction bottle, and the reaction is kept at 70°C for 2 hours and 90°C for 4 to 5 hours. The NCO percentage is measured to be 8% to 10%. The material is cooled and filtered to obtain a flame-retardant elastic prepolymer. Finally, 78.75 kg of the flame-retardant elastic prepolymer prepared above is evenly mixed with 8.75 kg of SCA-Y25M, and the material is filtered to obtain component B.

[0048] The mass ratio of component A and component B of the elastic flame retardant coating for rubber is 4:1, and they are mixed and stirred evenly.

[0049] Embodiment 3:

[0050] Preparation of component A of elastic flame-retardant coating for rubber: 14KgPH-50 polycarbonate resin and 8KgPCP-100L2 polycarbonate resin, 2.5KgYCK-2050 dispersant, 0.2KgYCK-1020 leveling agent, 0.5KgYCK-610 defoamer, 0.25Kg stannous chloride, 14Kg xylene, 10Kg butyl acetate and 6Kg butanone are added in sequence into a pull cylinder under stirring, and 14.25Kg ammonium polyphosphate, 4.75Kg pentaerythritol, 9KgGA-2 mica powder, 7Kg titanium dioxide, 8Kg aluminum tripolyphosphate and 2Kg zinc phosphate are added under stirring, and the mixture is ground with a basket sand mill to a fineness of less than 30μm after stirring. The material is filtered to obtain component A.

[0051] Preparation of component B of elastic flame retardant coating for rubber: First, add 15Kg of polycaprolactone diols with a molecular weight of 1000 and 5Kg of polycaprolactone diols with a molecular weight of 2000 containing phosphorus in the side chain, 5.1Kg of polyester diols with a phosphorus content in the side chain (the weight percentage of phosphorus content is greater than 12%), 3.35Kg of trimethylolpropane and 11Kg of xylene in a reaction bottle filled with nitrogen, heat and reflux for dehydration for 2h, then cool and discharge (hydroxy resin solution), then add 39.3Kg of 4,4'-dicyclohexylmethane diisocyanate (HMDI) and 0.02 kg of stannous octoate are used for primer, and then the refluxed and dehydrated hydroxy resin solution is added dropwise into the reaction bottle, and the reaction is kept at 70°C for 2 hours and 90°C for 4 to 5 hours. The NCO percentage is measured to be 8% to 10%. The material is cooled and filtered to obtain a flame-retardant elastic prepolymer. Finally, 78.75 kg of the flame-retardant elastic prepolymer prepared above is evenly mixed with 6.39 kg of SCA-Y25E, and the material is filtered to obtain component B.

[0052] The mass ratio of component A and component B of the elastic flame retardant coating for rubber is 4:1, and they are mixed and stirred evenly.

[0053] (4) Implementation effect:

[0054] The products of Examples 1-3 were applied to rubber (chloroprene rubber), and the dry film thickness of the rubber elastic flame retardant coating was 100 μm to 120 μm. After drying for 7 days or baking at 80°C for 4 hours, key performance tests such as cross-cut adhesion, peel strength and combustion oxygen index were conducted. The dry film thickness of the elongation at break and tensile strength casting sheet was 1 mm ± 0.1 mm, and the curing process was also drying for 7 days or baking at 80°C for 4 hours. The specific test results are as follows:

[0055] It can be seen from the above table that the present invention has achieved good technical effects.

[0056]

[0057] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

[0058] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

Claims

1. An elastic flame retardant coating for rubber, characterized in that: It is composed of component A and component B in a mass ratio of 3:1 to 5:1; The component A is composed of the following components by mass percentage: The component B is composed of the following components in terms of mass percentage: Flame retardant elastic prepolymer 90%~95% Contains 5% to 10% NCO silane coupling agent.

2. The elastic flame retardant coating for rubber according to claim 1, characterized in that: The flame retardant elastic prepolymer has an NCO percentage of 8% to 10% and is prepared by addition polymerization of two or more of polyester diols with different molecular weights and phosphorus-containing side chains, polycaprolactone diols with different molecular weights and phosphorus-containing side chains, trimethylolpropane, 4,4'-dicyclohexylmethane diisocyanate, a catalyst and a solvent.

3. The elastic flame retardant coating for rubber according to claim 1, characterized in that: The polycarbonate resin is at least one of UBE's UH-50, PH-50, UM-90 and Tosoh's PCP-100L2.

4. The elastic flame-retardant coating for rubber according to claim 1, characterized in that: The additive flame retardant is at least one of ammonium polyphosphate, aluminum hydroxide, magnesium hydroxide and pentaerythritol.

5. The elastic flame-retardant coating for rubber according to claim 1, characterized in that: The mica powder is at least one of GA-2, GA-4 and GD-2.

6. The elastic flame-retardant coating for rubber according to claim 1, characterized in that: The anti-rust filler is at least one of aluminum tripolyphosphate and zinc phosphate, the dispersant is at least one of YCK-2040, YCK-2050 and YCK-2070, the leveling agent is at least one of YCK-1010, YCK-1020 and YCK-1030, the defoamer is at least one of YCK-615, YCK-620 and YCK-610, and the catalyst is at least one of dibutyltin dilaurate, monobutyltin oxide and stannous chloride.

7. The elastic flame-retardant coating for rubber according to claim 1, characterized in that: The mixed solvent is at least one of xylene, butanone, cyclohexanone and butyl acetate.

8. The elastic flame-retardant coating for rubber according to claim 1, characterized in that: The NCO-containing silane coupling agent is at least one of SCA-Y25M, SCA-Y25Y and SCA-Y25E.

9. A method for preparing the elastic flame-retardant coating for rubber according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1) Preparation of component A: polycarbonate resin, dispersant, leveling agent, defoamer, catalyst and mixed solvent are sequentially added to a pull cylinder under stirring, and then added with additive flame retardant, mica powder, titanium dioxide and anti-rust filler under stirring, and then ground with a basket sand mill to a fineness of less than 30 μm, and the material is filtered to obtain component A; (2) Preparation of component B: first, a mixture of two or more of polycaprolactone diols with different molecular weights and phosphorus-containing side chains, polyester diols with different molecular weights and phosphorus-containing side chains, trimethylolpropane and a solvent are added to a reaction bottle filled with nitrogen, and the mixture is heated, refluxed and dehydrated, and then the mixture is discharged to obtain a solution containing a hydroxyl resin; then, 4,4'-dicyclohexylmethane diisocyanate and a catalyst are added to another reaction bottle filled with nitrogen for priming, and then the refluxed and dehydrated solution containing a hydroxyl resin is added dropwise to the reaction bottle, and the mixture is heated at 70°C and 90°C for gradient reaction, and the NCO percentage content is used as the final control index, and the mixture is filtered to obtain a flame-retardant elastic prepolymer; finally, the flame-retardant elastic prepolymer prepared above is mixed with an NCO silane coupling agent in a proportion, and the mixture is filtered to obtain component B; (3) Component A prepared in step (1) and component B prepared in step (2) are mixed according to a proportion and stirred evenly to obtain an elastic flame-retardant coating for rubber.

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