Dual-effect high and low temperature membrane

Abstract

The present invention relates to the technical field of shoe materials, and specifically to a dual-effect high and low temperature film, including a TPU high temperature layer, a hot melt adhesive layer, a polyurethane bottom layer, an intermediate layer and a polyurethane surface layer, wherein the polyurethane surface layer is a reversible temperature-changing surface layer formed by coating and drying a surface slurry including a thermochromic microcapsule; the thermochromic microcapsule has a double-layer wall material, the inner layer is a mercapto-modified silica shell, and the outer layer is an acrylate-modified polyurethane shell. The present invention introduces a reversible temperature-changing polymer material into the polyurethane surface layer, and the color disappears above the critical temperature to form a translucent effect, and changes back to a solid color effect below the critical temperature, thereby achieving a thermochromic effect; after ultraviolet light irradiation, the mercapto group in the mercapto-modified silica shell in the thermochromic microcapsule can click with the acrylate in the acrylate-modified polyurethane shell to generate a new molecular chain, thereby achieving normal repair and enhancing the structural integrity and impact resistance of the microcapsule.

Description

Technical Field

[0001] The invention relates to the technical field of shoe materials, and in particular to a dual-effect high and low temperature film. Background Art

[0002] High and low temperature films include high-temperature TPU (thermoplastic polyurethane) film layer and low-melting point TPU adhesive layer. The high-temperature TPU film layer plays a protective and wear-resistant role. The low-melting point TPU adhesive layer is melted and compounded on the product carrier under high-temperature heat and mechanical pressure during seamless hot pressing. It can be widely used in waterproofing, medical, outdoor, agriculture, decoration and other fields, such as shoe uppers.

[0003] In order to improve the surface aesthetics and feel, surface coating is generally performed. For example, the TPU veneer product disclosed in the Chinese patent document (CN109624422A) includes an adhesive layer, an intermediate layer and a surface layer on the surface of the high and low temperature film. In recent years, there has been a demand for the function of indicating temperature by color change. The Chinese patent document (CN113831758A) discloses a thermochromic microcapsule dye applied to clothing fabrics and the Chinese patent document (CN112980248A) discloses a thermochromic liquid crystal microcapsule ink applied to surface printing. These thermochromic microcapsules do not involve hot pressing operations, but since such products must be hot pressed in the semi-finished product lamination process and the finished product hot pressing application, thermochromic microcapsules are generally not used in the surface coating layer at present, but the TPU molecular chain of the high and low temperature film is modified by color change similar to the Chinese patent document (CN104448789A). Summary of the invention

[0004] The purpose of the invention is to provide a dual-effect high and low temperature film, which has a thermochromic effect and can self-repair and maintain the integrity of the capsule structure after hot pressing and compounding.

[0005] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is:

[0006] The dual-effect high and low temperature film comprises a TPU high temperature layer and a hot melt adhesive layer on the lower surface of the TPU high temperature layer, and a polyurethane bottom layer, a transparent polyurethane middle layer and a polyurethane surface layer on the upper surface of the TPU high temperature layer in sequence. The polyurethane surface layer is a reversible temperature-changing surface layer, and the reversible temperature-changing surface layer is formed by coating and drying a surface layer slurry including a third film-forming resin and thermochromic microcapsules.

[0007] Preferably, the bottom layer slurry used in the polyurethane bottom layer includes 100 parts of the first film-forming resin, 40-80 parts of the first organic solvent, 4-10 parts of the crosslinking agent and 2-4 parts of the crosslinking accelerator, with a viscosity of 3000-6000 cps and a coating amount of 150 g / m 2 -200g / m 2 .

[0008] Preferably, the intermediate layer slurry used in the transparent polyurethane intermediate layer includes 100 parts of the second film-forming resin, 0.5-1.5 parts of the leveling agent and 50-80 parts of the second organic solvent, with a viscosity of 2000-4000 cps and a coating amount of 80 g / m 2 -120g / m 2 .

[0009] Preferably, the surface slurry used in the reversible temperature-changing surface layer includes 100 parts of the third film-forming resin, 50-80 parts of the third organic solvent and 5-15 parts of the thermochromic microcapsules, with a viscosity of 2000-4000 cps and a coating amount of 120 g / m 2 -180g / m 2 .

[0010] Preferably, the thermochromic microcapsule is composed of a double-layer wall material and a core material, the inner layer of the double-layer wall material is a mercapto-modified silica shell, the outer layer of the double-layer wall material is an acrylate-modified polyurethane shell, and the core material is a thermochromic material.

[0011] Preferably, the method for preparing the thermochromic microcapsules comprises the following steps:

[0012] S11, mixing and heating the silicon source, the phase change material, the developer and the color former to obtain an oil phase;

[0013] S12, mixing anhydrous ethanol, deionized water and cetyltrimethylammonium bromide to obtain an aqueous phase;

[0014] S13, mixing the oil phase of step S11 and the water phase of step S12, dispersing the oil phase droplets in the water phase under high-speed shearing to obtain an O / W emulsion;

[0015] S14, adding ammonia water dropwise, adjusting the pH value to 8-9, reacting at 50°C-90°C for 3h-6h, then adding silane coupling agent KH590 to continue the reaction and grafting KH590 on the surface of the silica shell, and drying to obtain microcapsules with mercapto-modified silica shells;

[0016] S15, mixing the dried diisocyanate, photoinitiator and the microcapsules with mercapto-modified silica shells in step S14 in an organic solvent, adding diol after uniform dispersion, reacting to obtain a polyurethane prepolymer terminated with -NCO groups, then adding pentaerythritol triallyl ether to react and consume the remaining -NCO, thereby in situ polymerizing on the surface of the mercapto-modified silica shell to generate an acrylate-modified polyurethane shell, washing with water, and drying to obtain thermochromic microcapsules, and the mixture of phase change material, color developer and color former is used as the thermochromic core material of the thermochromic microcapsules.

[0017] Preferably, the silicon source is tetraethyl orthosilicate.

[0018] Preferably, the phase change material is methyl octadecanoate, the color developer is bisphenol AF, and the color former is crystal violet lactone.

[0019] Preferably, the mass ratio of the color former, the developer and the phase change material is 1:3-4:30-35.

[0020] Preferably, the photoinitiator is photoinitiator OMBB or photoinitiator TPO.

[0021] Beneficial Effects

[0022] The dual-effect high and low temperature film of the present invention introduces a reversible temperature-changing polymer material into the polyurethane surface layer. When the temperature reaches above the critical temperature of the phase-change material, the color of the polyurethane surface layer disappears and becomes a translucent effect, and when the temperature drops to the critical temperature of the phase-change material, it will return to the original solid color effect, thereby achieving a thermochromic effect. The dual-effect high and low temperature film of the present invention is not irradiated with ultraviolet light after the finished product is made, but is irradiated with ultraviolet light of 250-450nm wavelength after hot pressing, so that the mercapto group in the mercapto-modified silica shell in the thermochromic microcapsule and the acrylate in the acrylate-modified polyurethane shell can click and react to generate new molecular chains, thereby achieving normal repair and enhancing the structural integrity and impact resistance of the thermochromic microcapsule. Even if it encounters impact or friction during use after hot pressing, the thermochromic microcapsule is not easy to break and can play a normal temperature indication role. In addition, since the thermochromic capsules of high and low temperature films may crack during storage or transportation, ultraviolet light exposure for a certain period of time before hot pressing can also reduce the possibility that the polyurethane surface discoloration effect caused by hot pressing will not meet the expected effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the structure of the dual-effect high and low temperature membrane of the present invention. DETAILED DESCRIPTION Example 1

[0024] like Figure 1As shown, this embodiment provides a dual-effect high and low temperature film, including a TPU high temperature layer 11 and a hot melt adhesive layer 12 on the lower surface of the TPU high temperature layer 11, and a polyurethane bottom layer 21, a transparent polyurethane middle layer 22 and a polyurethane surface layer 23 on the upper surface of the TPU high temperature layer 11 in sequence. During production and processing, the surface layer slurry is coated on the surface of the release paper, and heated and dried at 130°C to form a polyurethane surface layer 23; then the middle layer slurry is coated on the polyurethane surface layer 23, and heated and dried at 135°C to form a transparent polyurethane middle layer 22; then the bottom layer slurry is coated on the transparent polyurethane middle layer 22, and dried at 125°C to half dry, forming a polyurethane bottom layer 21; finally, a TPU semi-finished product consisting of a TPU high temperature layer 11 and a hot melt adhesive layer 12 is dry-laminated on the polyurethane bottom layer 21, thereby obtaining a high and low temperature film product.

[0025] In this embodiment, the bottom layer slurry used in the polyurethane bottom layer 21 includes 100 parts of the first film-forming resin, 50 parts of DMF, 30 parts of TOL, 8 parts of the crosslinking agent S061 and 2 parts of the crosslinking accelerator S062, with a viscosity of 4000 cps and a coating amount of 180 g / m 2 .

[0026] In this embodiment, the intermediate layer slurry used in the transparent polyurethane intermediate layer 22 includes 100 parts of the second film-forming resin, 0.8 parts of the leveling agent BYK 333 and 60 parts of DMF, with a viscosity of 2800 cps and a coating amount of 100 g / m 2 .

[0027] In this embodiment, the polyurethane surface layer 23 is a reversible temperature-changing surface layer. The surface layer slurry used in the reversible temperature-changing surface layer includes 100 parts of a third film-forming resin, 50 parts of DMF and 15 parts of thermochromic microcapsules, with a viscosity of 2500 cps and a coating amount of 150 g / m 2 .

[0028] The first film-forming resin, the second film-forming resin and the third film-forming resin are all dry-process polyurethane resins commonly used by technicians in this field and can be purchased directly from the market. For example, the first film-forming resin is PU-3045, the second film-forming resin is ST-8630, and the third film-forming resin is LT-80.

[0029] The preparation method of the thermochromic microcapsule comprises the following steps: S11, tetraethyl orthosilicate, methyl octadecanoate, bisphenol AF and crystal violet lactone are mixed and heated to obtain an oil phase, wherein the mass ratio of crystal violet lactone, bisphenol AF and methyl octadecanoate is 1:3:30, and the mass ratio of the mixture of methyl octadecanoate, bisphenol AF and crystal violet lactone to tetraethyl orthosilicate is 2:1; S12, anhydrous ethanol, deionized water and hexadecyltrimethylammonium bromide are mixed at a ratio of 1 mL:2 mL :22mg mixed to obtain an aqueous phase; S13, mixing the oil phase of step S11 and the aqueous phase of step S12, the mass ratio of the oil phase to the aqueous phase is 1:2.5, and the oil phase droplets are dispersed in the aqueous phase under the action of high-speed shear to obtain an O / W emulsion; S14, adding ammonia water, adjusting the pH value to 8-9, reacting at 80°C for 6h, and then adding silane coupling agent KH590 to continue the reaction and grafting KH590 on the surface of the silica shell, the silane coupling agent KH590 and tetraethyl orthosilicate The molar ratio of isophorone diisocyanate to tetraethyl orthosilicate is 1:1, and drying is performed to obtain microcapsules with a mercapto-modified silica shell; S15, the dried isophorone diisocyanate, the photoinitiator TPO and the microcapsules with a mercapto-modified silica shell of step S14 are mixed in an organic solvent DMF, the mass ratio of isophorone diisocyanate to tetraethyl orthosilicate is 3:1, and after uniform dispersion, polytetramethylene glycol PTMG-2000 is added to react to obtain a polyurethane prepolymer terminated with a -NCO group. The product is then added with pentaerythritol triallyl ether to react and consume the remaining -NCO. The molar ratio of isophorone diisocyanate, PTMG-2000 and pentaerythritol triallyl ether is 1:0.9:0.2, thereby in situ polymerization is performed on the surface of the mercapto-modified silica shell to generate an acrylate-modified polyurethane shell. The thermochromic microcapsules are washed with water and dried. A mixture of methyl octadecanoate, bisphenol AF and crystal violet lactone is used as the thermochromic core material of the thermochromic microcapsules. Example 2

[0030] like Figure 1 As shown, this embodiment provides a dual-effect high and low temperature film, including a TPU high temperature layer 11 and a hot melt adhesive layer 12 on the lower surface of the TPU high temperature layer 11, and a polyurethane bottom layer 21, a transparent polyurethane middle layer 22 and a polyurethane surface layer 23 on the upper surface of the TPU high temperature layer 11 in sequence. During production and processing, the surface layer slurry is coated on the surface of the release paper, and heated and dried at 130°C to form a polyurethane surface layer 23; then the middle layer slurry is coated on the polyurethane surface layer 23, and heated and dried at 135°C to form a transparent polyurethane middle layer 22; then the bottom layer slurry is coated on the transparent polyurethane middle layer 22, and dried at 125°C to half dry, forming a polyurethane bottom layer 21; finally, a TPU semi-finished product consisting of a TPU high temperature layer 11 and a hot melt adhesive layer 12 is dry-laminated on the polyurethane bottom layer 21, thereby obtaining a high and low temperature film product.

[0031] In this embodiment, the bottom layer slurry used in the polyurethane bottom layer 21 includes 100 parts of the first film-forming resin, 40 parts of DMF, 20 parts of TOL, 5 parts of the crosslinking agent S061 and 3 parts of the crosslinking accelerator S062, with a viscosity of 5000 cps and a coating amount of 150 g / m 2 .

[0032] In this embodiment, the intermediate layer slurry used in the transparent polyurethane intermediate layer 22 includes 100 parts of the second film-forming resin, 1.0 parts of the leveling agent BYK 333 and 65 parts of DMF, with a viscosity of 2500 and a coating amount of 120 g / m 2 .

[0033] In this embodiment, the polyurethane surface layer 23 is a reversible temperature-changing surface layer. The surface layer slurry used in the reversible temperature-changing surface layer includes 100 parts of a third film-forming resin, 60 parts of DMF and 10 parts of thermochromic microcapsules, with a viscosity of 3000 cps and a coating amount of 165 g / m 2 .

[0034] The first film-forming resin, the second film-forming resin and the third film-forming resin are all dry-process polyurethane resins commonly used by technicians in this field and can be purchased directly from the market. For example, the first film-forming resin is PU-3045, the second film-forming resin is ST-8630, and the third film-forming resin is LT-80.

[0035] The preparation method of the thermochromic microcapsule comprises the following steps: S11, tetraethyl orthosilicate, methyl octadecanoate, bisphenol AF and crystal violet lactone are mixed and heated to obtain an oil phase, wherein the mass ratio of crystal violet lactone, bisphenol AF and methyl octadecanoate is 1:3.5:35, and the mass ratio of the mixture of methyl octadecanoate, bisphenol AF and crystal violet lactone to tetraethyl orthosilicate is 2.5:1; S12, anhydrous ethanol, deionized water and hexadecyltrimethylammonium bromide are mixed at 1 mL: 2mL:22.5mg are mixed to obtain an aqueous phase; S13, the oil phase of step S11 and the aqueous phase of step S12 are mixed, the mass ratio of the oil phase to the aqueous phase is 1:2.5, and the oil phase droplets are dispersed in the aqueous phase under the action of high-speed shear to obtain an O / W emulsion; S14, ammonia water is added dropwise, the pH value is adjusted to 8-9, the reaction is carried out at 80°C for 6h, and then the silane coupling agent KH590 is added to continue the reaction to graft KH590 on the surface of the silica shell, and the silane coupling agent KH590 and the orthosilicon are The molar ratio of tetraethyl orthosilicate to isophorone diisocyanate is 1:1, and drying is performed to obtain microcapsules with mercapto-modified silica shells; S15, the dried isophorone diisocyanate, the photoinitiator OMBB and the microcapsules with mercapto-modified silica shells of step S14 are mixed in an organic solvent DMF, the mass ratio of isophorone diisocyanate to tetraethyl orthosilicate is 3:1, and after uniform dispersion, polytetramethylene glycol PTMG-2000 is added to react to obtain a polyurethane terminated with an -NCO group. prepolymer, and then pentaerythritol triallyl ether is added to react and consume the remaining -NCO. The molar ratio of isophorone diisocyanate, PTMG-2000 and pentaerythritol triallyl ether is 1:0.9:0.2, thereby in situ polymerization on the surface of the mercapto-modified silica shell to generate an acrylate-modified polyurethane shell, which is washed with water and dried to obtain thermochromic microcapsules. A mixture of methyl octadecanoate, bisphenol AF and crystal violet lactone is used as the thermochromic core material of the thermochromic microcapsules.

[0036] The critical color change temperature of the reversible temperature-changing surface layer of embodiments 1 and 2 is 31°C. When the temperature reaches above 31°C, the color of the polyurethane surface layer 23 disappears, thus becoming a translucent effect; and when the temperature drops below 30°C, it will return to the original solid color (blue) effect. In specific applications, a printed pattern layer can be provided between the transparent polyurethane intermediate layer 22 and the polyurethane bottom layer 21 as required, so that the printed pattern layer is prominent when the temperature exceeds 31°C. After hot pressing, the dual-effect high and low temperature film of this embodiment is irradiated with ultraviolet light of a wavelength of 250-450nm, so that the mercapto group in the mercapto-modified silica shell in the thermochromic microcapsule can click with the acrylate in the acrylate-modified polyurethane shell to generate a new molecular chain, thereby achieving the restoration of normality and enhancing the structural integrity and impact resistance of the thermochromic microcapsule.

[0037] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for illustrating the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which shall fall within the scope of the present invention to be protected. The scope of protection of the present invention shall be defined by the attached claims and their equivalents.

Claims

1. A dual-effect high and low temperature film, comprising a TPU high temperature layer, a hot melt adhesive layer on the lower surface of the TPU high temperature layer, and a polyurethane bottom layer, a transparent polyurethane middle layer and a polyurethane surface layer on the upper surface of the TPU high temperature layer, characterized in that: The polyurethane surface layer is a reversible temperature-changing surface layer, which is formed by coating and drying a surface slurry including a third film-forming resin and thermochromic microcapsules; The thermochromic microcapsule is composed of a double-layer wall material and a core material, the inner layer of the double-layer wall material is a mercapto-modified silica shell, the outer layer of the double-layer wall material is an acrylate-modified polyurethane shell, and the core material is a thermochromic core material; The preparation method of the thermochromic microcapsule comprises the following steps: S11, mixing and heating the silicon source, the phase change material, the developer and the color former to obtain an oil phase; S12, mixing anhydrous ethanol, deionized water and cetyltrimethylammonium bromide to obtain an aqueous phase; S13, mixing the oil phase of step S11 and the water phase of step S12, dispersing the oil phase droplets in the water phase under high-speed shearing to obtain an O / W emulsion; S14, adding ammonia water dropwise, adjusting the pH value to 8-9, reacting at 50°C-90°C for 3h-6h, then adding silane coupling agent KH590 to continue the reaction and grafting KH590 on the surface of the silica shell, and drying to obtain microcapsules with mercapto-modified silica shells; S15, mixing the dried diisocyanate, photoinitiator and the microcapsules with mercapto-modified silica shells in step S14 in an organic solvent, adding diol after uniform dispersion, reacting to obtain a polyurethane prepolymer terminated with -NCO groups, then adding pentaerythritol triallyl ether to react and consume the remaining -NCO, thereby in situ polymerizing on the surface of the mercapto-modified silica shell to generate an acrylate-modified polyurethane shell, washing with water, and drying to obtain thermochromic microcapsules, and the mixture of phase change material, color developer and color former is used as the thermochromic core material of the thermochromic microcapsules.

2. The dual-effect high and low temperature membrane according to claim 1, characterized in that: The bottom layer slurry used in the polyurethane bottom layer includes 100 parts of a first film-forming resin, 40-80 parts of a first organic solvent, 4-10 parts of a crosslinking agent and 2-4 parts of a crosslinking accelerator, with a viscosity of 3000-6000 cps and a coating amount of 150 g / m 2 -200g / m 2 .

3. The dual-effect high and low temperature membrane according to claim 1, characterized in that: The intermediate layer slurry used in the transparent polyurethane intermediate layer includes 100 parts of the second film-forming resin, 0.5-1.5 parts of the leveling agent and 50-80 parts of the second organic solvent, with a viscosity of 2000-4000 cps and a coating amount of 80 g / m 2 -120g / m 2 .

4. The dual-effect high and low temperature membrane according to claim 1, characterized in that: The surface slurry used in the reversible temperature-changing surface layer includes 100 parts of the third film-forming resin, 50-80 parts of the third organic solvent and 5-15 parts of the temperature-sensitive color-changing microcapsules, the viscosity is 2000-4000cps, and the coating amount is 120g / m 2 -180g / m 2 .

5. The dual-effect high and low temperature membrane according to claim 1, characterized in that: The silicon source is tetraethyl orthosilicate.

6. The dual-effect high and low temperature membrane according to claim 1, characterized in that: The phase change material is methyl octadecanoate, the color developer is bisphenol AF, and the color former is crystal violet lactone.

7. The dual-effect high and low temperature membrane according to claim 1 or 6, characterized in that: The mass ratio of the color former, the developer and the phase change material is 1:3-4:30-35.

8. The dual-effect high and low temperature membrane according to claim 1, characterized in that: The photoinitiator is photoinitiator OMBB or photoinitiator TPO.

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