Temperature change pigment and printing process based on temperature change pigment

Abstract

The invention provides a temperature change pigment and a printing process based on the temperature change pigment. The printing process comprises the following steps: 1) adding a stabilizer, a reinforcing agent, a washing resistant agent and a hand feeling improver into water, uniformly mixing, adding a waterborne polyurethane-organic silicon copolymer resin adhesive under a stirring condition, and finally adding modified temperature change microcapsules to obtain temperature change pigment ink; and 2) sequentially carrying out pretreatment, screen printing, pre-drying, baking curing and post-treatment on the cotton and linen fabric to finish printing of the cotton and linen fabric. The washable agent and carboxyl in the waterborne polyurethane-organosilicone copolymer resin adhesive form a three-dimensional network, network pores are filled with the reinforcing agent to improve compactness, a chemical-physical cross-linked network is constructed through the washable agent and the reinforcing agent, in addition, pre-drying, baking curing and post-treatment are sequentially carried out based on the specific temperature change pigment after silk-screen printing, and therefore the temperature-sensitive printing ink is obtained. Low-temperature crosslinking is realized through stepped curing and microwave after-treatment, and the long-term stability of printing is improved.

Description

Technical Field

[0001] This invention relates to the field of textile printing technology, specifically to a thermochromic pigment and a printing process based on the thermochromic pigment. Background Technology

[0002] Thermochromic materials are increasingly used in textile printing, especially in smart clothing, anti-counterfeiting labels, and functional home textiles, demonstrating significant value. Traditional thermochromic printing processes primarily rely on microencapsulation technology, encapsulating thermochromic compounds within melamine resin or polyurethane wall materials, and then using screen printing or digital printing to create patterns. However, existing technologies still have the following drawbacks: 1) Traditional microencapsulated wall materials have low mechanical strength and are prone to breakage during washing. Commercially available products show excessive color contrast decay after five standard washes and are also prone to hydrolysis and failure in humid and hot environments, severely limiting product lifespan; 2) Existing processes increase the amount of adhesive used to improve adhesion, often with acrylic resin accounting for more than 65%, resulting in a stiff feel in the printed area and a bending stiffness reaching 3.0 cN / cm. 2 This seriously affects the wearing experience of close-fitting textiles; 3) Most thermochromic microcapsules on the market have a heat resistance of 110-120℃, but polyurethane adhesives need to be cured at a high temperature of over 160℃, which leads to thermal decomposition and inactivation of the core material. At the same time, nano-reinforcing agents are prone to agglomerate in ink, resulting in excessive loss of pattern precision.

[0003] Currently, there are improvements made to thermochromic pigments and to the process routes, but it is still difficult to achieve high washability, ultra-soft feel, and compatibility with low-temperature processes. Therefore, a new printing process is urgently needed. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the shortcomings of existing technologies, this invention provides a thermochromic pigment and a printing process based on the thermochromic pigment, thus solving the problems mentioned in the background section.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] According to a first aspect of the present invention, a thermochromic pigment is provided, comprising, by mass fraction:

[0009] 15%–30% modified thermochromic microcapsules;

[0010] 40%–60% waterborne polyurethane-silicone copolymer resin adhesive;

[0011] 3%–8% of feel improver;

[0012] 1% to 4% of detergent;

[0013] 0.5% to 3% reinforcing agent;

[0014] 0.5% to 2% stabilizer;

[0015] The remaining water.

[0016] This invention employs a waterborne polyurethane-silicone copolymer resin adhesive. The silicone segments provide flexibility, while the waterborne polyurethane enhances adhesion. The coupling agent on the surface of the modified thermochromic microcapsule forms covalent bonds between the microcapsule wall material and the silicone resin, thereby improving interfacial bonding. The wash-resistant agent reacts with the carboxyl groups of the silicone copolymer resin to form a three-dimensional cross-linked network. Simultaneously, synergistic hand feel improvers, reinforcing agents, and stabilizers achieve the process requirements of high fastness, soft hand feel, and low-temperature printing.

[0017] Preferably, the modified thermochromic microcapsule includes a color-changing core material and a wall material coating the surface of the color-changing core material. The color-changing core material is selected from at least one of crystal violet lactone, bisphenol A, spiropyran, long-chain fatty acids, Schiff base derivatives, and palmitol. The wall material is selected from any one of melamine resin, polyurethane, or gelatin-gum arabic.

[0018] Preferably, the modified thermochromic microcapsules have a particle size of 3–10 μm and a wall material thickness of 0.2–0.5 μm.

[0019] Preferably, the modified thermochromic microcapsules are modified by any one of silane coupling agents and titanate coupling agents.

[0020] Preferably, the feel modifier is selected from at least one of polyether-modified silicone oil, amino-modified silicone oil, polyether-modified siloxane, or organosilicon elastomer.

[0021] Preferably, the wash-resistant agent is selected from at least one of trimethylolpropane-tris(2-methyl-1-aziridine)propionate, polycarbodiimide, ethylene glycol diglycidyl ether, and vinylbisoxazoline.

[0022] Preferably, the reinforcing agent is selected from at least one of hydrophobic nano-silica, sheet clay, or carbon nanotubes.

[0023] Preferably, the stabilizer is selected from at least one of light stabilizers, heat stabilizers, phase change stabilizers, or antioxidants.

[0024] Specifically, the light stabilizer is selected from at least one of bis(2,2,6,6-tetramethylpiperidine) sebacate and 2-hydroxy-4-octyloxybenzophenone;

[0025] The heat stabilizer is selected from at least one of zinc stearate, cerium stearate, and dibenzoylmethane;

[0026] The phase change stabilizer is selected from at least one of TEMPO oxidized cellulose and 4A zeolite;

[0027] The antioxidant is selected from at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris(2,4-di-tert-butylphenyl)phosphite.

[0028] According to a second aspect of the present invention, a printing process based on thermochromic pigments is provided, comprising the following steps:

[0029] 1) Add stabilizer, reinforcing agent, wash-resistant agent and hand feel improver to water and mix evenly. Add waterborne polyurethane-silicone copolymer resin binder under stirring. Finally, add modified thermochromic microcapsules to obtain thermochromic pigment ink.

[0030] 2) The cotton and linen fabric is pre-treated, screen printed, pre-dried, baked and cured, and then post-treated to complete the printing process.

[0031] Preferably, the pretreatment step is as follows: at 50-60°C, the cotton and linen fabric is placed in a complex containing pectinase and cellulase for 20-30 minutes.

[0032] The screen printing process uses a 150-mesh screen, a squeegee angle of 70°, a pressure of 0.25–0.3 MPa, and a speed of 0.5–1 m / min.

[0033] The pre-drying temperature is 60-80℃, and the wind speed is 5-8m / s;

[0034] The baking conditions are as follows: first heat to 100℃ for 1 minute, then heat to 130℃ for 3 minutes, and finally cool rapidly to 60℃.

[0035] The post-treatment steps are as follows: first, immerse the sample in an aqueous fluorocarbon resin at 110°C for 1 minute, then irradiate it with microwave for 30 seconds, and finally pad it with a tea polyphenol-chitosan composite emulsion at 95°C for 2 minutes.

[0036] Beneficial effects

[0037] This invention provides a thermochromic pigment and a printing process based on the thermochromic pigment. It has the following beneficial effects:

[0038] (1) The thermochromic pigment provided in this solution forms a three-dimensional network with the carboxyl groups in the wash-resistant agent and the waterborne polyurethane-silicone copolymer resin binder. The reinforcing agent fills the network pores to improve the density. Through the chemical-physical cross-linked network constructed by the wash-resistant agent and the reinforcing agent, the ΔEab loss after 20 standard water washes can be reduced to less than 15%. In addition, due to the addition of a hand feel improver, it can maintain 0.8 cN / cm 2 Its ultra-soft feel enhances the lifespan and comfort of cotton fabrics.

[0039] (2) This solution provides a printing process based on thermochromic pigments. Based on specific thermochromic pigments, after screen printing, the printing process is pre-baked, baked and cured and then post-treated. Through step curing and microwave finishing, low-temperature cross-linking is achieved, which improves the long-term stability of the printing. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with embodiments. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention.

[0042] To better illustrate the content of this invention, the following description is provided in conjunction with specific embodiments.

[0043] Example 1

[0044] A thermochromic pigment comprises 22% modified thermochromic microcapsules with a particle size of 5 μm and a wall thickness of 0.3 μm, wherein the core material of the modified thermochromic microcapsules is a composition of crystal violet lactone and bisphenol A, the wall material is melamine resin, and the modified thermochromic microcapsules are modified by a titanate coupling agent; 50% waterborne polyurethane-silicone copolymer resin binder; 5% polyether-modified silicone oil; 2.5% polycarbodiimide; 1.5% hydrophobic nano-silica; 0.5% bis(2,2,6,6-tetramethylpiperidine) sebacate; 0.5% TEMPO oxidized cellulose; and the balance being water.

[0045] The printing process is as follows:

[0046] Step 1: Add 0.5% bis(2,2,6,6-tetramethylpiperidine) sebacate, 0.5% TEMPO oxidized cellulose, 1.5% hydrophobic nano silica, 2.5% polycarbodiimide and 5% polyether modified silicone oil to water and mix evenly. Under stirring, add 50% waterborne polyurethane-organic silicone copolymer resin binder, and finally add 22% modified thermochromic microcapsules to obtain thermochromic pigment ink.

[0047] Step 2: Place the cotton and linen fabric in the pectinase-cellulase complex and treat it at 55°C for 25 minutes;

[0048] Step 3: Screen printing is performed on the pretreated cotton and linen fabric. The mesh size is set to 150 mesh, the squeegee angle is set to 70°, the pressure is 0.28 MPa, and the speed is 0.8 m / min.

[0049] Step 4: Pre-dry the screen-printed cotton and linen fabric at 70℃ with a wind speed of 6m / s.

[0050] Step 5: First, bake the pre-baked cotton and linen fabric at 100℃ for 1 minute, then raise the temperature to 130℃ and bake for 3 minutes, and finally cool it rapidly to 60℃.

[0051] Step 6: First, immerse the baked cotton and linen fabric in a 5% concentration of water-based fluorocarbon resin at 110°C for 1 minute, then irradiate it with an 800W microwave for 30 seconds, and finally tie-dye it with a tea polyphenol-chitosan composite emulsion at 95°C for 2 minutes to complete the printing process.

[0052] Example 2

[0053] The preparation method of this embodiment is the same as that of Example 1, except that the thermochromic pigment includes 25% modified thermochromic microcapsules with a particle size of 7 μm and a wall thickness of 0.5 μm. The core material of the modified thermochromic microcapsules is a combination of spiropyran and long-chain fatty acids, and the wall material is polyurethane. The modified thermochromic microcapsules are modified by a silane coupling agent. 60% waterborne polyurethane-organic silicone copolymer resin binder; 3% polyether modified silicone oil; 2% polycarbodiimide; 1% hydrophobic nano-silica; 0.5% sebacic acid bis(2,2,6,6-tetramethylpiperidine) ester; 0.5% TEMPO oxidized cellulose; and the balance is water.

[0054] Example 3

[0055] The preparation method of this embodiment is the same as that of Example 1, except that the thermochromic pigment includes 25% modified thermochromic microcapsules with a particle size of 3 μm and a wall thickness of 0.2 μm. The core material of the modified thermochromic microcapsules is a combination of Schiff base derivative and palmitol, and the wall material is gelatin-gum arabic. The modified thermochromic microcapsules are modified by a silane coupling agent; 60% waterborne polyurethane-organic silicone copolymer resin binder; 3% amino-modified silicone oil; 2% trimethylolpropane-tris(2-methyl-1-aziridine)propionate; 1% flake clay; 0.5% bis(2,2,6,6-tetramethylpiperidine) sebacate; 0.5% TEMPO oxidized cellulose; and the balance being water.

[0056] Comparative Example 1

[0057] The preparation method of this comparative example is the same as that of Example 1, except that the thermochromic microcapsules in this comparative example were not modified.

[0058] Comparative Example 2

[0059] The preparation method of this comparative example is the same as that of Example 1, except that the wash-resistant agent polycarbodiimide was not added in this comparative example.

[0060] Comparative Example 3

[0061] The preparation method of this comparative example is the same as that of Example 1, except that the waterborne polyurethane adhesive is replaced with the waterborne polyurethane-silicone copolymer resin adhesive in Example 1.

[0062] Comparative Example 4

[0063] The preparation method in this comparative example is the same as that in Example 1. The difference is that in step 5, the pre-dried cotton and linen fabric is directly baked at 130°C for 4 minutes and then rapidly cooled to 60°C.

[0064] Comparative Example 5

[0065] The preparation method in this comparative example is the same as that in Example 1, except that the microwave irradiation step is omitted in step 6.

[0066] The cotton and linen fabrics printed in Examples 1 to 3 and the cotton and linen fabrics printed in Comparative Examples 1 to 5 were tested for washability, softness and temperature change cycle stability. The test results are shown in Table 1.

[0067] Table 1

[0068]

[0069] According to the data in Table 1, a three-dimensional network is formed by water-based polyurethane-silicone copolymer resin adhesive and wash-resistant agent. The reinforcing agent fills the pores of the three-dimensional network to improve density and fix thermochromic microcapsules in the three-dimensional network. In conjunction with a specific printing process, the bonding strength of the thermochromic microcapsules is increased, and the wash resistance is improved. In addition, the softness of the printed fabric is improved by the synergistic effect of silicone copolymer resin and hand feel improver. The structural integrity of the thermochromic microcapsules is protected by the stepped baking and rapid cooling process, which improves the temperature cycle stability of the thermochromic microcapsules. By combining temperature-changing pigments and printing process, the printed fabric has excellent density and low dynamic friction coefficient.

[0070] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A thermochromic pigment, characterized in that: By mass fraction, including: 15%–30% modified thermochromic microcapsules; 40%–60% waterborne polyurethane-silicone copolymer resin adhesive; 3%–8% of feel improver; 1% to 4% of detergent; 0.5% to 3% reinforcing agent; 0.5% to 2% stabilizer; The remaining water.

2. The thermochromic pigment according to claim 1, characterized in that: The modified thermochromic microcapsule includes a color-changing core material and a wall material coating the surface of the color-changing core material. The color-changing core material is selected from at least one of crystal violet lactone, bisphenol A, spiropyran, long-chain fatty acids, Schiff base derivatives, and palmitol. The wall material is selected from any one of melamine resin, polyurethane, or gelatin-gum arabic.

3. The thermochromic pigment according to claim 2, characterized in that: The modified thermochromic microcapsules have a particle size of 3–10 μm and a wall material thickness of 0.2–0.5 μm.

4. The thermochromic pigment according to claim 1, characterized in that: The modified thermochromic microcapsules are modified using either a silane coupling agent or a titanate coupling agent.

5. A thermochromic pigment according to claim 1, characterized in that: The feel modifier is selected from at least one of polyether-modified silicone oil, amino-modified silicone oil, polyether-modified siloxane, or organosilicon elastomer.

6. The thermochromic pigment according to claim 1, characterized in that: The wash-resistant agent is selected from at least one of trimethylolpropane-tris(2-methyl-1-aziridine)propionate, polycarbodiimide, ethylene glycol diglycidyl ether, and vinyl bisoxazoline.

7. A thermochromic pigment according to claim 1, characterized in that: The reinforcing agent is selected from at least one of hydrophobic nano-silica, sheet clay, or carbon nanotubes.

8. A thermochromic pigment according to claim 1, characterized in that: The stabilizer is selected from at least one of light stabilizers, heat stabilizers, phase change stabilizers, or antioxidants.

9. A printing process based on thermochromic pigments according to any one of claims 1 to 8, characterized in that: Includes the following steps: 1) Add stabilizer, reinforcing agent, wash-resistant agent and hand feel improver to water and mix evenly. Add waterborne polyurethane-silicone copolymer resin binder under stirring. Finally, add modified thermochromic microcapsules to obtain thermochromic pigment ink. 2) The cotton and linen fabric is pre-treated, screen printed, pre-dried, baked and cured, and then post-treated to complete the cotton and linen fabric printing.

10. A printing process based on thermochromic pigments according to claim 9, characterized in that: The pretreatment step is as follows: at 50-60°C, cotton and linen fabric is placed in a complex containing pectinase and cellulase for 20-30 minutes. The screen printing process uses a 150-mesh screen, a squeegee angle of 70°, a pressure of 0.25–0.3 MPa, and a speed of 0.5–1 m / min. The pre-drying temperature is 60-80℃, and the wind speed is 5-8m / s; The baking conditions are as follows: first heat to 100℃ for 1 minute, then heat to 130℃ for 3 minutes, and finally cool rapidly to 60℃. The post-treatment steps are as follows: first, immerse the sample in an aqueous fluorocarbon resin at 110°C for 1 minute, then irradiate it with microwave for 30 seconds, and finally pad it with a tea polyphenol-chitosan composite emulsion at 95°C for 2 minutes.

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