Heat transfer film as well as preparation method and application thereof

Abstract

The invention discloses a heat transfer film as well as a preparation method and application thereof. The heat transfer film comprises a frame layer, a foaming layer, a reinforcing layer and a transfer release layer which are sequentially arranged, the preparation raw materials of the modified aramid fibers comprise aramid fibers modified with amide groups and polyamide nanoparticles; the foaming layer is prepared from the following raw materials: styrene synthetic rubber, a heat-conducting material, a conductive material, inorganic filler, foaming microspheres, a coupling agent and a vulcanizing agent; the reinforcing layer is prepared from the following raw materials: acrylate rubber, a heat-conducting material, a conductive material, an inorganic filler, a coupling agent and a vulcanizing agent; the ink has the characteristics of insulation and heat conduction and is suitable for transfer printing of electronic ink.

Description

Technical Field

[0001] The invention belongs to the technical field of thermal transfer, and in particular relates to a thermal transfer film and a preparation method and application thereof. Background Art

[0002] Traditional thermal transfer films or thermal transfer cloths are usually made of silicone rubber materials, which can meet the basic requirements for film material performance in general ink transfer processes. However, in the printing application of electronic ink, due to its special formulation requirements and the unique nature of the transfer process, the existing thermal transfer films fail to fully meet the relevant performance requirements. Specifically, electronic ink usually contains a certain proportion of mineral oil, and traditional thermal transfer films have poor oil resistance and are easily affected by oily components, resulting in deformation of the film material and a significant decrease in strength. In addition, the surface tension of existing thermal transfer films is relatively high, which limits their application in high-sharpness transfer processes and cannot achieve delicate and precise transfer effects. At the same time, the insulation and thermal conductivity of existing thermal transfer films have not yet reached the ideal level, especially when in contact with metal rollers, they cannot effectively meet the dual requirements of thermal conductivity and electrical insulation. Therefore, it is urgent to develop a thermal transfer film with superior thermal conductivity and stability. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a thermal transfer film having the characteristics of low surface tension and insulation and heat conduction, which is suitable for the transfer of electronic ink.

[0004] According to a first aspect of the present invention, a thermal transfer film is provided, comprising a frame layer, a foaming layer, a support layer and a transfer release layer arranged in sequence;

[0005] The raw materials for preparing the frame layer include modified aramid fiber;

[0006] The raw materials for preparing the modified aramid fiber include aramid fiber modified with amide groups and polyamide nanoparticles;

[0007] The raw materials for preparing the foaming layer include: styrene-based synthetic rubber, thermal conductive material, conductive material, inorganic filler, foaming microspheres, coupling agent and vulcanizing agent;

[0008] The raw materials for preparing the reinforcement layer include: acrylic rubber, thermal conductive material, conductive material, inorganic filler, coupling agent and vulcanizing agent;

[0009] The raw materials for preparing the transfer release layer include: perfluoroethylene-propylene copolymer.

[0010] According to the first aspect of the present invention, there are at least the following beneficial effects:

[0011] During the modification process, amide groups (–CONH2) were introduced into aramid fibers, which have strong hydrogen bonding and polarity. Therefore, hydrogen bonds were formed with polyamide nanoparticles to enhance the binding force between the two, promote the uniform dispersion of polyamide nanoparticles, reduce the aggregation between particles, and thus improve the overall performance of the material. Polyamide nanoparticles have high thermal conductivity. When they are evenly dispersed in aramid fibers, they can effectively enhance the thermal conductivity of the material. The stable structure formed by hydrogen bonds between amide groups and polyamide nanoparticles ensures the high efficiency of the heat transfer path and effectively improves the thermal conductivity.

[0012] Under high pressure, the foam layer can undergo directional compression deformation, and the modified aramid fiber, as the skeleton layer, plays a stabilizing and reinforcing role in the supporting structure. When the foamed microspheres are deformed, the modified aramid fiber can effectively share part of the external pressure, maintain the stability of the material and reduce the non-uniformity of the deformation. This allows the composite material to withstand pressure and quickly recover its shape during compression.

[0013] According to some embodiments of the present invention, the thermally conductive material includes at least one of nano-boron nitride, silicon nitride, aluminum oxide and carbon nanotubes.

[0014] According to some embodiments of the present invention, the conductive material includes at least one of graphene nanosheets and conductive carbon black.

[0015] According to some embodiments of the present invention, the inorganic filler includes at least one of titanium dioxide and barium silicate.

[0016] According to some embodiments of the present invention, the vulcanizing agent comprises:

[0017] According to some embodiments of the present invention, the weight ratio of the aramid fiber modified with amide groups to the polyamide nanoparticles is 3.5 to 5:1.

[0018] According to a second aspect of the present invention, a method for preparing a thermal transfer film is provided, comprising the following steps:

[0019] The frame layer and the foaming layer are molded into a supporting layer material, molded, vulcanized, coated with a transfer release layer, and then cured.

[0020] According to some embodiments of the present invention, the raw materials for preparing the aramid fiber modified with amide groups include:

[0021] A1. removing impurities from the aramid fiber and reacting with an aminosilane coupling agent to obtain an aramid fiber modified with an amino group;

[0022] A2. Catalyzing the reaction between the amino-modified aramid fiber and an acyl chloride compound to obtain an amide-modified aramid fiber.

[0023] According to some embodiments of the present invention, the impurity removal method includes: washing the aramid fiber and drying it at 60-80° C. for 2 hours.

[0024] According to some embodiments of the present invention, the method for preparing the modified aramid fiber comprises:

[0025] The polyamide nanoparticles are dispersed and dissolved in amide-modified aramid fibers to react and then remove impurities.

[0026] According to some embodiments of the present invention, the impurity removal step includes: soaking the aramid fiber modified with amide bonds in ethylene dichloride at 40-50° C. for 2-3 hours, and then washing and drying.

[0027] The surface of the aramid fiber is swollen with ethylene dichloride to form micropores, which increases the contact area between the fiber surface and the polyamide nanoparticles, helps the penetration and uniform distribution of the nanoparticles, and improves the mechanical properties of the material.

[0028] According to some embodiments of the present invention, the aminosilane includes at least one of γ-aminopropyltriethoxysilane, γ-aminopropyltriphenoxysilane and 3-aminopropyldimethylethoxysilane.

[0029] According to some embodiments of the present invention, the temperature of the mixing reaction in step A1 is 40-70°C.

[0030] According to some embodiments of the present invention, the catalyst for the catalytic reaction in step A2 includes pyridine, triethylamine and diethylamine.

[0031] According to some embodiments of the present invention, the raw materials for preparing the foaming layer include, by weight: 90 to 110 parts of styrene-based synthetic rubber, 25 to 35 parts of thermal conductive materials, 8 to 12 parts of conductive materials, 7 to 15 parts of inorganic fillers, 8 to 12 parts of foamed microspheres, 3 to 5 parts of coupling agents, and 2 to 4 parts of vulcanizing agents.

[0032] According to some embodiments of the present invention, the method for preparing the foaming layer comprises, by weight, mixing and kneading the raw materials for preparing the foaming layer and then adding a vulcanizing agent and kneading the mixture.

[0033] According to some embodiments of the present invention, the raw materials for preparing the support layer include, by weight: 90 to 110 parts of acrylic rubber, 25 to 35 parts of thermal conductive material, 8 to 12 parts of conductive material, 7 to 15 parts of inorganic filler, 3 to 5 parts of coupling agent, and 2 to 4 parts of vulcanizing agent.

[0034] According to some embodiments of the present invention, the method for preparing the support layer comprises, by weight, mixing and kneading the raw materials for preparing the support layer and then adding a vulcanizing agent and kneading the mixture.

[0035] According to some embodiments of the present invention, the vulcanization method is: vulcanization at 110-125° C. for 110-130 min, and then vulcanization at 160-175° C. for 110-130 min.

[0036] According to a third aspect of the present invention, application of a thermal transfer film in electronic ink printing is proposed.

[0037] According to some embodiments of the present invention, in the application, the method for attaching the thermal transfer film includes:

[0038] A1. After removing impurities from the surface of the substrate to be attached, the thermal transfer film and the substrate are pre-positioned and initially bonded using a pressure roller;

[0039] A2. Preheat curing process: After 1-10 minutes of heat curing pretreatment at 60-150°C, use 80-200kV electron beam for irradiation curing, with a dose range of 20-200kGy.

[0040] The main purpose of the pretreatment process in step A2 is to promote the formation of a preliminary interface between the thermal transfer film and the surface of the substrate, creating good conditions for subsequent electron beam curing; an electron beam with an acceleration voltage of 80-200kV is used for irradiation curing, and the dose range is 20-200kGy. This process is the main curing link, and can quickly achieve deep crosslinking at room temperature; this dual curing process significantly reduces the temperature, time and energy consumption required for the traditional full heat curing process by positioning thermal curing as a pretreatment process. Preheat curing only takes 1-10 minutes to complete the interface pretreatment, while electron beam curing can achieve rapid deep curing at room temperature, greatly improving the overall process efficiency. By rationally designing the process parameters and coordination sequence of thermal curing and electron beam curing, this process can not only ensure the formation of a stable interface bond between the thermal transfer film and the substrate, but also achieve rapid curing through electron beam curing, significantly improving production efficiency. Among them, the heat curing process, as a pre-curing process, can promote the formation of preliminary chemical bonds between the thermal transfer film and the substrate at a relatively low temperature and in a relatively short time, laying the foundation for subsequent electron beam curing; while electron beam curing can quickly complete the cross-linking reaction at room temperature to achieve deep curing. This process design not only avoids the thermal deformation problem that may be caused by the traditional single heat curing process, but more importantly, since the heat curing is positioned as a pre-curing process, compared with the traditional full heat curing process, it has achieved significant reductions in time consumption, energy consumption, and processing space requirements, and has obvious process advantages and economic benefits. Through this innovative dual-curing process design, the present invention successfully solves the efficiency bottleneck and quality control problems faced by thermal transfer films in practical applications. DETAILED DESCRIPTION

[0041] The following will be combined with the embodiments to clearly and completely describe the concept of the present invention and the technical effects produced, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0042] In the description of the present invention, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0043] Unless otherwise specified, "room temperature" in the present invention means 25°C±5°C.

[0044] Unless otherwise specified, "about" in the present invention means that the allowable error is within ±2%.

[0045] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. If the manufacturers of the reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0046] A first aspect of the present invention provides a thermal transfer film, comprising a frame layer, a foaming layer, a reinforcement layer and a transfer release layer arranged in sequence;

[0047] The raw materials for preparing the frame layer include modified aramid fiber;

[0048] The raw materials for preparing the modified aramid fiber include aramid fiber modified with amide groups and polyamide nanoparticles;

[0049] The raw materials for preparing the foaming layer include: styrene-based synthetic rubber, thermal conductive material, conductive material, inorganic filler, foaming microspheres, coupling agent and vulcanizing agent;

[0050] The raw materials for preparing the reinforcement layer include: acrylic rubber, thermal conductive material, conductive material, inorganic filler, coupling agent and vulcanizing agent;

[0051] The raw materials for preparing the transfer release layer include: perfluoroethylene-propylene copolymer.

[0052] In combination with the first aspect, in some embodiments of the present invention, the weight ratio of the aramid fiber modified with amide groups to the polyamide nanoparticles is 3.5 to 5:1.

[0053] In combination with the second aspect, in some embodiments of the present invention, a method for preparing a thermal transfer film is provided, comprising the following steps:

[0054] The frame layer and the foaming layer are molded into a supporting layer material, molded, vulcanized, coated with a transfer release layer, and then cured.

[0055] In combination with the second aspect, in some embodiments of the present invention, the raw materials for preparing the aramid fiber modified with amide groups include:

[0056] A1. removing impurities from the aramid fiber and reacting with an aminosilane coupling agent to obtain an aramid fiber modified with an amino group;

[0057] A2. Catalyzing the reaction between the amino-modified aramid fiber and an acyl chloride compound to obtain an amide-modified aramid fiber.

[0058] In combination with the second aspect, in some embodiments of the present invention, the impurity removal method includes: washing the aramid fiber and drying it at 60-80° C. for 2 hours.

[0059] In combination with the second aspect, in some embodiments of the present invention, the method for preparing the modified aramid fiber includes:

[0060] The polyamide nanoparticles are dispersed and dissolved in amide-modified aramid fibers to react and then remove impurities.

[0061] In combination with the second aspect, in some embodiments of the present invention, the impurity removal step includes: soaking the aramid fiber modified with amide bonds in ethylene dichloride at 40-50° C. for 2-3 hours, and then washing and drying.

[0062] In combination with the second aspect, in some embodiments of the present invention, the aminosilane includes at least one of γ-aminopropyltriethoxysilane, γ-aminopropyltriphenoxysilane and 3-aminopropyldimethylethoxysilane.

[0063] In combination with the second aspect, in some embodiments of the present invention, the temperature of the mixing reaction in step A1 is 40-70°C.

[0064] In combination with the second aspect, in some embodiments of the present invention, the catalyst for the catalytic reaction in step A2 includes pyridine, triethylamine and diethylamine.

[0065] In combination with the second aspect, in some embodiments of the present invention, the raw materials for preparing the foaming layer include, by weight: 90-110 parts of styrene-based synthetic rubber, 25-35 parts of thermal conductive material, 8-12 parts of conductive material, 7-15 parts of inorganic filler, 8-12 parts of foamed microspheres, 3-5 parts of coupling agent, and 2-4 parts of vulcanizing agent.

[0066] In combination with the second aspect, in some embodiments of the present invention, the method for preparing the foaming layer comprises, by weight: mixing and kneading the raw materials for preparing the foaming layer and then adding a vulcanizing agent and kneading the mixture.

[0067] In combination with the second aspect, in some embodiments of the present invention, the raw materials for preparing the support layer include, by weight: 90 to 110 parts of acrylic rubber, 25 to 35 parts of thermal conductive material, 8 to 12 parts of conductive material, 7 to 15 parts of inorganic filler, 3 to 5 parts of coupling agent, and 2 to 4 parts of vulcanizing agent.

[0068] In combination with the second aspect, in some embodiments of the present invention, the method for preparing the support layer comprises, by weight: mixing and kneading the raw materials for preparing the support layer and then adding a vulcanizing agent and kneading.

[0069] In combination with the second aspect, in some embodiments of the present invention, the vulcanization method is: vulcanization at 110-125° C. for 110-130 min, and then vulcanization at 160-175° C. for 110-130 min.

[0070] In conjunction with the third aspect, in some embodiments of the present invention, application of thermal transfer film in electronic ink printing is proposed.

[0071] Example 1

[0072] This embodiment discloses a thermal transfer film, which includes a frame layer, a foaming layer, a support layer and a transfer release layer arranged in sequence;

[0073] The preparation method of the thermal transfer film in this embodiment is as follows:

[0074] S1.1: The aramid fiber was washed three times with deionized water, ethanol and anhydrous ethanol to remove surface impurities and then dried in an oven at 60°C for 2 hours;

[0075] S1.2: Add 1.5 mL of γ-aminopropyltriethoxysilane (APTES) to 50 mL of toluene, put the cleaned and dried aramid fiber into the solution, react at 60 ° C for 4 hours, and stir evenly; after the reaction is completed, rinse with deionized water and ethanol to remove unreacted aminosilane and dry at 60 ° C for 6 hours to obtain aminosilane-modified aramid fiber;

[0076] S1.3: Add 1 g of triethylamine catalyst and o-chlorobenzoyl chloride (2 g) into the reaction container, control the reaction temperature to 60°C, and the reaction time to 6 hours; keep stirring during the reaction. After the reaction is completed, wash the fiber with deionized water to remove unreacted o-chlorobenzoyl chloride and other solvents to obtain aramid fiber modified with amide bonds;

[0077] S1.4: Soak the aramid fiber modified with amide bonds in ethylene dichloride at 40 degrees Celsius for 2 hours, then wash it with deionized water to remove the residual solvent, and then vacuum dry it;

[0078] S1.5: adding polyamide nanoparticles to a DMF solution, ultrasonically treating for 2 hours to form a uniformly dispersed solution, immersing the dried amide bond-modified aramid fiber in the solution, and stirring at room temperature for 18 hours to obtain the modified aramid fiber;

[0079] S2.1: Put the following components in parts by weight into an internal mixer for internal mixing: 100 parts of styrene-butadiene copolymer, 30 parts of nano boron nitride, 10 parts of graphene nanosheets, 10 parts of titanium dioxide, 10 parts of polystyrene foam microspheres, and 4 parts of 3-aminopropyltriethoxysilane; the heating temperature of the internal mixing is 60°C, and the internal mixing time is 60 minutes; discharge; add the internally mixed material to an open mixer, add 2 parts by weight of benzoyl peroxide, and mix three times to obtain a foaming layer;

[0080] S3.1: 100 parts of acrylic rubber, 30 parts of nano boron nitride, 10 parts of graphene nanosheets, 10 parts of barium silicate, and 4 parts of coupling agent (Maitu A-1100); the heating temperature of the banburying is 60°C, and the banburying time is 60 minutes; discharging; adding the banburying material to an open mill, and then adding 2 parts by weight of benzoyl peroxide, and opening the mill for 3 times to obtain a reinforcement layer;

[0081] S4.1: Add the modified aramid fiber and the foaming layer material into the mold in sequence, and use a molding machine with a capacity of more than 10 tons for molding; then continue to add the reinforcement layer material, and use a molding machine with a capacity of more than 10 tons for molding; the ratio of the foaming layer material to the reinforcement layer material is 4.5:3.5;

[0082] S5.1: Vulcanize at 120°C for 120 min, and then vulcanize at 170°C for 120 min; then coat with perfluoroethylene propylene copolymer (Daikin GLS-213DRA), bake at 160°C for 30 min, to form a transfer release layer with a thickness of about 20 μm, and finally obtain a thermal transfer film.

[0083] Example 2

[0084] This embodiment discloses a thermal transfer film, which includes a frame layer, a foaming layer, a support layer and a transfer release layer arranged in sequence;

[0085] The preparation method of the thermal transfer film in this embodiment is as follows:

[0086] S1.1: The aramid fiber was washed three times with deionized water, ethanol and anhydrous ethanol to remove surface impurities and then dried in an oven at 60°C for 2 hours;

[0087] S1.2: Add 1.5 mL of γ-aminopropyltriethoxysilane (APTES) to 50 mL of toluene, put the cleaned and dried aramid fiber into the solution, react at 60 ° C for 4 hours, and stir evenly; after the reaction is completed, rinse with deionized water and ethanol to remove unreacted aminosilane and dry at 60 ° C for 6 hours to obtain aminosilane-modified aramid fiber;

[0088] S1.3: Add 1 g of triethylamine and o-chlorobenzoyl chloride (2 g) into the reaction container, control the reaction temperature to 60°C, and the reaction time to 6 hours; keep stirring during the reaction. After the reaction is completed, wash the fiber with deionized water to remove unreacted o-chlorobenzoyl chloride and other solvents to obtain aramid fiber modified with amide bonds;

[0089] S1.4: Soak the aramid fiber modified with amide bonds in ethylene dichloride at 40 degrees Celsius for 2 hours, then wash it with deionized water to remove the residual solvent, and then vacuum dry it;

[0090] S1.5: adding polyamide nanoparticles to a DMF solution, ultrasonically treating for 2 hours to form a uniformly dispersed solution, immersing the dried amide bond-modified aramid fiber in the solution, and stirring at room temperature for 18 hours to obtain the modified aramid fiber;

[0091] S2.1: Put the following components in parts by weight into an internal mixer for internal mixing: 100 parts of styrene-butadiene copolymer, 30 parts of nano boron nitride, 10 parts of graphene nanosheets, 10 parts of titanium dioxide, 10 parts of polystyrene foam microspheres, and 4 parts of 3-aminopropyltriethoxysilane; the heating temperature of the internal mixing is 60°C, and the internal mixing time is 60 minutes; discharge; add the internally mixed material to an open mixer, add 2 parts by weight of benzoyl peroxide, and mix three times to obtain a foaming layer;

[0092] S3.1: 100 parts of acrylic rubber, 30 parts of nano boron nitride, 10 parts of conductive carbon black, 10 parts of barium silicate, and 4 parts of coupling agent (Maitu A-1100); the heating temperature of the banburying is 60°C, and the banburying time is 60 minutes; discharging; adding the banburying materials to an open mill, and then adding 2 parts by weight of benzoyl peroxide, and opening the mill for 3 times to obtain a reinforcement layer;

[0093] S4.1: Add the modified aramid fiber and the foaming layer material into the mold in sequence, and use a molding machine with a capacity of more than 10 tons for molding; then continue to add the reinforcement layer material, and use a molding machine with a capacity of more than 10 tons for molding; the ratio of the foaming layer material to the reinforcement layer material is 4.5:3.5;

[0094] S5.1: Vulcanize at 120°C for 120 min, and then vulcanize at 170°C for 120 min; then coat with perfluoroethylene propylene copolymer (Daikin GLS-213DRA), bake at 160°C for 30 min, to form a transfer release layer with a thickness of about 20 μm, and finally obtain a thermal transfer film.

[0095] Example 3

[0096] This embodiment discloses a thermal transfer film, which includes a frame layer, a foaming layer, a support layer and a transfer release layer arranged in sequence;

[0097] The preparation method of the thermal transfer film in this embodiment is as follows:

[0098] S1.1: The aramid fiber was washed three times with deionized water, ethanol and anhydrous ethanol to remove surface impurities and then dried in an oven at 60°C for 2 hours;

[0099] S1.2: Add 1.5 mL of γ-aminopropyltriethoxysilane (APTES) to 50 mL of toluene, put the cleaned and dried aramid fiber into the solution, react at 60 ° C for 4 hours, and stir evenly; after the reaction is completed, rinse with deionized water and ethanol to remove unreacted aminosilane and dry at 60 ° C for 6 hours to obtain aminosilane-modified aramid fiber;

[0100] S1.3: Add 1 g of triethylamine and o-chlorobenzoyl chloride (2 g) into the reaction container, control the reaction temperature to 60°C, and the reaction time to 6 hours; keep stirring during the reaction. After the reaction is completed, wash the fiber with deionized water to remove unreacted o-chlorobenzoyl chloride and other solvents to obtain aramid fiber modified with amide bonds;

[0101] S1.4: Soak the aramid fiber modified with amide bonds in ethylene dichloride at 40 degrees Celsius for 2 hours, then wash it with deionized water to remove the residual solvent, and then vacuum dry it;

[0102] S1.5: adding polyamide nanoparticles to a DMF solution, ultrasonically treating for 2 hours to form a uniformly dispersed solution, immersing the dried amide bond-modified aramid fiber in the solution, and stirring at room temperature for 18 hours to obtain the modified aramid fiber;

[0103] S2.1: Put the following components in parts by weight into an internal mixer for internal mixing: 90 parts of styrene-butadiene copolymer, 35 parts of nano boron nitride, 12 parts of graphene nanosheets, 10 parts of titanium dioxide, 10 parts of polystyrene foam microspheres, and 4 parts of 3-aminopropyltriethoxysilane; the heating temperature of the internal mixing is 60°C, and the internal mixing time is 60 minutes; discharge; add the internally mixed material to an open mixer, add 2 parts by weight of benzoyl peroxide, and mix three times to obtain a foaming layer;

[0104] S3.1: 90 parts of acrylic rubber, 30 parts of nano boron nitride, 10 parts of conductive carbon black, 10 parts of barium silicate, and 4 parts of coupling agent (Maitu A-1100); the heating temperature of the banburying is 60°C, and the banburying time is 60 minutes; discharging; adding the banburying materials to an open mill, and then adding 2 parts by weight of benzoyl peroxide, and opening and refining for 3 times to obtain a reinforcement layer;

[0105] S4.1: Add the modified aramid fiber and the foaming layer material into the mold in sequence, and use a molding machine with a capacity of more than 10 tons for molding; then continue to add the reinforcement layer material, and use a molding machine with a capacity of more than 10 tons for molding; the ratio of the foaming layer material to the reinforcement layer material is 4.5:3.5;

[0106] S5.1: Vulcanize at 120°C for 120 min, and then vulcanize at 170°C for 120 min; then coat with perfluoroethylene propylene copolymer (Daikin GLS-213DRA), bake at 160°C for 30 min, to form a transfer release layer with a thickness of about 20 μm, and finally obtain a thermal transfer film.

[0107] Example 4

[0108] This embodiment discloses a thermal transfer film, which includes a frame layer, a foaming layer, a support layer and a transfer release layer arranged in sequence;

[0109] The method for preparing the thermal transfer film in this embodiment differs from that in Embodiment 1 in that the step S1.4 is not included:

[0110] S1.1: The aramid fiber was washed three times with deionized water, ethanol and anhydrous ethanol to remove surface impurities and then dried in an oven at 60°C for 2 hours;

[0111] S1.2: Add 1.5 mL of γ-aminopropyltriethoxysilane (APTES) to 50 mL of toluene, put the cleaned and dried aramid fiber into the solution, react at 60 ° C for 4 hours, and stir evenly; after the reaction is completed, rinse with deionized water and ethanol to remove unreacted aminosilane and dry at 60 ° C for 6 hours to obtain aminosilane-modified aramid fiber;

[0112] S1.3: Add 1 g of triethylamine catalyst and o-chlorobenzoyl chloride (2 g) into the reaction container, control the reaction temperature to 60°C, and the reaction time to 6 hours; keep stirring during the reaction. After the reaction is completed, wash the fiber with deionized water to remove unreacted o-chlorobenzoyl chloride and other solvents to obtain aramid fiber modified with amide bonds;

[0113] S1.4: adding polyamide nanoparticles to a DMF solution, ultrasonically treating for 2 hours to form a uniformly dispersed solution, immersing the aramid fiber with dry-modified amide bonds in the solution, and stirring at room temperature for 18 hours to obtain the modified aramid fiber;

[0114] S2.1: Put the following components in parts by weight into an internal mixer for internal mixing: 100 parts of styrene-butadiene copolymer, 30 parts of nano boron nitride, 10 parts of graphene nanosheets, 10 parts of titanium dioxide, 10 parts of polystyrene foam microspheres, and 4 parts of 3-aminopropyltriethoxysilane; the heating temperature of the internal mixing is 60°C, and the internal mixing time is 60 minutes; discharge; add the internally mixed material to an open mixer, add 2 parts by weight of benzoyl peroxide, and mix three times to obtain a foaming layer;

[0115] S3.1: 100 parts of acrylic rubber, 30 parts of nano boron nitride, 10 parts of graphene nanosheets, 10 parts of barium silicate, and 4 parts of coupling agent (Maitu A-1100); the heating temperature of the banburying is 60°C, and the banburying time is 60 minutes; discharging; adding the banburying material to an open mill, and then adding 2 parts by weight of benzoyl peroxide, and opening the mill for 3 times to obtain a reinforcement layer;

[0116] S4.1: Add the modified aramid fiber and the foaming layer material into the mold in sequence, and use a molding machine with a capacity of more than 10 tons for molding; then continue to add the reinforcement layer material, and use a molding machine with a capacity of more than 10 tons for molding; the ratio of the foaming layer material to the reinforcement layer material is 4.5:3.5;

[0117] S5.1: Vulcanize at 120°C for 120 min, and then vulcanize at 170°C for 120 min; then coat with perfluoroethylene propylene copolymer (Daikin GLS-213DRA), bake at 160°C for 30 min, to form a transfer release layer with a thickness of about 20 μm, and finally obtain a thermal transfer film.

[0118] Comparative Example 1

[0119] This example discloses a thermal transfer film. The difference between this comparative example and Example 1 is that the aramid fiber is only modified with the amino group but not with the amide group.

[0120] Comparative Example 2

[0121] This example discloses a thermal transfer film. The difference between this comparative example and Example 1 is that the polyamide nanoparticles in Example 1 are replaced by carbon nanotubes.

[0122] Test Example 1

[0123] The thermal transfer film prepared in the embodiment was subjected to a performance test. The test method is as follows and the test results are shown in Table 1.

[0124] Thermal conductivity test method: probe method;

[0125] Surface conductivity test method: probe method;

[0126] Heat-resistant and oil-resistant load permanent compression deformation test method: Use a micrometer to test the thickness of the thermal transfer film, marked as H1. Use the HPA manual pressure tester to give the thermal transfer film a pressure of 2kg / square centimeter, and place the tester in a constant temperature oil pan filled with mineral oil with a boiling point of more than 200 degrees, making sure that the mineral oil does not pass the thermal transfer film. Heat the constant temperature oil pan to 150 degrees and keep the temperature constant. After 500 hours, take out the tester and remove the thermal transfer film. After leaving it at room temperature for 24 hours, use a micrometer to test the thickness of the thermal transfer film, marked as H2. Use the following formula to calculate permanent compression deformation.

[0127] Deformation (percentage) = (H1-H2) / H1*100%;

[0128] Table 1 Thermal transfer film performance test results

[0129]

[0130]

[0131] In Comparative Example 1, the interaction between the amino group and the polyamide nanoparticles is weaker than that between the amide group, resulting in poor dispersion of the polyamide nanoparticles in the fibers, affecting the deformation recovery ability, thermal conductivity and overall structural stability of the material.

[0132] In Comparative Example 2, the bonding force between the carbon nanotubes and the aramid fibers is weak, so excellent thermal conductivity cannot be achieved. When dispersed in the composite material, the carbon nanotubes may aggregate to form a large block structure.

[0133] The embodiments of the present invention are described in detail above, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A thermal transfer film, characterized in that: It includes a frame layer, a foaming layer, a reinforcement layer and a transfer release layer which are arranged in sequence; The raw materials for preparing the frame layer include modified aramid fiber; The raw materials for preparing the modified aramid fiber include aramid fiber modified with amide groups and polyamide nanoparticles; The raw materials for preparing the foaming layer include: styrene-based synthetic rubber, thermal conductive material, conductive material, inorganic filler, foaming microspheres, coupling agent and vulcanizing agent; The raw materials for preparing the reinforcement layer include: acrylic rubber, thermal conductive material, conductive material, inorganic filler, coupling agent and vulcanizing agent; The raw materials for preparing the transfer release layer include: perfluoroethylene-propylene copolymer.

2. The thermal transfer film according to claim 1, characterized in that: The weight ratio of the aramid fiber modified with amide groups to the polyamide nanoparticles is 3.5-5:

1.

3. A method for preparing a thermal transfer film according to claim 1 or 2, characterized in that: The following steps are involved: The frame layer and the foaming layer are molded into a supporting layer material, molded, vulcanized, coated with a transfer release layer, and then cured.

4. The preparation method according to claim 3, characterized in that: The raw materials for preparing the aramid fiber modified with amide groups include: A1. removing impurities from the aramid fiber and reacting with an aminosilane coupling agent to obtain an aramid fiber modified with an amino group; A2. Catalyzing the reaction between the amino-modified aramid fiber and an acyl chloride compound to obtain an amide-modified aramid fiber.

5. The preparation method according to claim 3, characterized in that: The preparation method of the modified aramid fiber comprises: The polyamide nanoparticles are dispersed and dissolved in amide-modified aramid fibers to react and then remove impurities.

6. The preparation method according to claim 5, characterized in that: The impurity removal step comprises: soaking the aramid fiber modified with amide bonds in ethylene dichloride at 40-50° C. for 2-3 hours, and then washing and drying.

7. The preparation method according to claim 3, characterized in that: In parts by weight, the foaming layer includes: 90-110 parts of styrene-based synthetic rubber, 25-35 parts of thermal conductive material, 8-12 parts of conductive material, 7-15 parts of inorganic filler, 8-12 parts of foamed microspheres, 3-5 parts of coupling agent, and 2-4 parts of vulcanizing agent.

8. The preparation method according to claim 3, characterized in that: In parts by weight, the support comprises: 90 to 110 parts of acrylic rubber, 25 to 35 parts of thermal conductive material, 8 to 12 parts of conductive material, 7 to 15 parts of inorganic filler, 3 to 5 parts of coupling agent, and 2 to 4 parts of vulcanizing agent.

9. The preparation method according to claim 7, characterized in that: The vulcanization treatment method is: vulcanization at 110-125° C. for 110-130 minutes, and then vulcanization at 160-175° C. for 110-130 minutes.

10. Use of the thermal transfer film according to claim 1 or 2 in electronic ink printing.

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