An EVA composite hot melt adhesive for UV printing 3D icons, its preparation method and application

Abstract

This invention discloses an EVA composite hot melt adhesive for UV printing 3D icons, its preparation method, and its application. The EVA composite hot melt adhesive comprises: thermoplastic polyurethane elastomer, ethylene-vinyl acetate copolymer, polyvinyl acetate, film-forming agent, viscosity modifier, and polypropylene; the VA content of the ethylene-vinyl acetate copolymer is ≥28wt%. The EVA composite hot melt adhesive of this invention uses EVA with a high VA content as the matrix, and adds TPU to improve the tensile properties of the material and enhance the hydrophilicity of EVA, thereby strengthening its wash fastness after heat pressing and film formation. The addition of polyacetic acid improves the adhesion of the material and also enhances its wash fastness. Through the synergistic effect of the components, the material achieves excellent tensile and wash resistance properties, enabling the formation of wear-resistant and wash-resistant 3D icons on textiles.

Description

Technical Field

[0001] This invention belongs to the field of printing materials technology, specifically relating to an EVA composite hot melt adhesive for UV printing of three-dimensional icons, its preparation method, and its application. Background Technology

[0002] Currently, printing on fabrics is mainly planar, while 3D color label printing can not only create diverse patterns but also enhance the tactile feel and visual richness of textiles, making it very popular with consumers. Foam printing involves printing resin-based pigments containing foaming agents onto fabrics, which are then steamed at high temperatures, causing the printed patterns to bubble and create an embossed effect; however, this foaming material has poor mechanical properties, is easily deformed, and has poor washability.

[0003] Existing processes for printing 3D stereoscopic color icons on fabrics include screen printing, lettering film processing, and silicone embossing. However, these printing processes are relatively complex and require significant equipment investment. For example, screen printing requires plate making and color matching to create 3D stereoscopic color icons. Lettering film or silicone embossing involves applying color, baking, laser cutting out the desired graphics or icons, manually removing excess material, and then heat pressing. These processes are complex, costly, and have low yields, making the printing of 3D stereoscopic color icons on fabrics extremely rare.

[0004] UV printing technology mainly refers to the use of special UV inks on a UV printing machine to achieve partial or overall UV printing effects. It is a plate-free, full-color digital printing process that can print color photo-quality images on surfaces such as T-shirts, glass, sheets, plastics, stone, and leather, without material limitations. It completes printing in one pass without the need for plate making, producing vibrant and rich colors, wear resistance, UV protection, and is simple and convenient to operate with fast image printing speed. Compared with traditional offset printing, UV printing has the advantages of vibrant colors and simple and fast production process, and has a broad market prospect. However, the tensile strength of existing UV printed products is relatively low, making them prone to tearing and deformation, which limits their application in printing color three-dimensional 3D icons on fabrics.

[0005] Patent CN108728017A discloses a hot melt adhesive for fabrics and its preparation method. The hot melt adhesive includes EVA matrix resin, tackifier, viscosity modifier, filler and crosslinking agent, and is prepared by a combination of melt blending and light irradiation. The prepared hot melt adhesive has good heat resistance and crack resistance; however, this hot melt adhesive fails to solve the problem of poor wash fastness of EVA material. Summary of the Invention

[0006] The purpose of this invention is to overcome the defects and shortcomings of existing EVA hot melt adhesives and to provide an EVA composite hot melt adhesive with excellent tensile properties and adhesion, and high wash fastness.

[0007] Another object of the present invention is to provide a method for preparing EVA composite hot melt adhesive.

[0008] Another object of the present invention is to provide an application of the above-mentioned EVA composite hot melt adhesive in the preparation of heat transfer three-dimensional icon materials.

[0009] Another objective of this invention is to provide a heat transfer 3D icon material.

[0010] The above-mentioned objective of this invention is achieved through the following technical solution:

[0011] This invention protects an EVA composite hot melt adhesive, characterized in that it comprises the following components in parts by weight:

[0012] 15-25 parts of thermoplastic polyurethane elastomer,

[0013] 30-50 parts of ethylene-vinyl acetate copolymer

[0014] 8-16 parts of polyvinyl acetate,

[0015] 2-10 parts of film-forming agent

[0016] 1-5 parts viscosity modifier

[0017] Polypropylene 0.1-2 parts;

[0018] The VA content of the ethylene-vinyl acetate copolymer is ≥28wt%.

[0019] The EVA composite hot melt adhesive of the present invention uses ethylene-vinyl acetate copolymer (EVA) with a high VA content as the matrix and adds thermoplastic polyurethane elastomer (TPU) for compounding, which improves the material's ductility and tensile effect, and also improves the hydrophilicity of EVA, enhancing its wash fastness after hot pressing and film formation; the addition of polyacetic acid can improve the material's adhesion and wash fastness; through the synergistic effect of each component, the material achieves excellent tensile properties and wash resistance.

[0020] In addition, the EVA composite hot melt adhesive of the present invention also contains a specific amount of polypropylene, which can improve the hardness and film shear properties of the material, which is beneficial for waste removal after heat transfer processing, and the adhesive film is not easy to string or leave residue.

[0021] It should be noted that the present invention requires controlling the VA content in the EVA, which can improve the compatibility between EVA and TPU, improve the ductility and tensile properties of the material, improve the poor water resistance of EVA, and improve the wash fastness of the material.

[0022] In some embodiments, the film-forming agent is polyurethane resin and / or acrylic resin, preferably polyurethane resin; both polyurethane resin and acrylic resin have good film-forming effects, and polyurethane resin has more prominent tensile strength, which is beneficial to improving the tensile effect of the product.

[0023] Preferably, the polyurethane resin has a viscosity of 4000-6000 mPa·s at 25°C.

[0024] In some embodiments, the polyvinyl acetate resin has a viscosity of 1-4 mPa·s at 25°C and a molecular weight of 25,000-35,000.

[0025] In some embodiments, the viscosity modifier is LDPE; LDPE has good flowability, which can solve the flow effect of liquid during coating, and has good high temperature resistance, making it less prone to high temperature precipitation.

[0026] In some embodiments, the VA content of the ethylene-vinyl acetate copolymer is ≥30wt%, preferably, the VA content of the ethylene-vinyl acetate copolymer is 30-50wt%.

[0027] In some embodiments, the ethylene-vinyl acetate copolymer has a melt flow rate of 1-40 g / 10 min at 190°C and 2.16 kg, preferably 5-35 g / 10 min.

[0028] In some embodiments, the polypropylene may be selected from any one of homopolymer polypropylene, block copolymer polypropylene, and random copolymer polypropylene, preferably random copolymer polypropylene, and more preferably metallocene random copolymer polypropylene.

[0029] In some of these embodiments, the following components by mass fraction are included:

[0030] 18-22 parts of thermoplastic polyurethane elastomer

[0031] 35-45 parts of ethylene-vinyl acetate copolymer,

[0032] 3-8 parts of polyvinyl acetate,

[0033] 10-14 parts of film-forming agent

[0034] 1-3 parts viscosity modifier

[0035] Polypropylene 0.5-1.5 parts.

[0036] In some embodiments, the dispersant is 1-3 parts, the wetting agent is 1-3 parts, the curing agent is 1-3 parts, and the leveling agent is 0.5-2 parts.

[0037] A method for preparing an EVA composite hot melt adhesive includes the following steps: adding the raw materials of the specified amount to an organic solvent and stirring evenly at a stirring temperature of 55-65℃, then casting and molding to obtain the EVA composite hot melt adhesive.

[0038] It should be noted that the preparation method of the present invention requires controlling the heating temperature within a specific range. If the temperature is too high, crystallization is likely to occur; if the temperature is too low, agglomeration is likely to occur.

[0039] Application of an EVA composite hot melt adhesive in the preparation of UV-printed 3D icons.

[0040] A UV-printed 3D icon material, made by UV printing using EVA composite hot melt adhesive.

[0041] Compared with the prior art, the beneficial effects of the present invention are:

[0042] This invention provides an EVA composite hot melt adhesive, using EVA resin with a high VA content as the matrix, and adding TPU to improve the extensibility and tensile properties of the material after film formation, as well as improve the hydrophilicity of EVA and enhance its wash fastness after heat pressing. The addition of polyacetic acid improves the material's adhesion and wash fastness. Through the synergistic effect of the components, excellent tensile properties and wash resistance are achieved. Attached Figure Description

[0043] Figure 1 This is a physical image of the 3D stereoscopic icon material for fabric heat transfer printing according to Embodiment 4 of the present invention.

[0044] Figure 2 In this invention Figure 1 A photo of the product in its stretched state after washing. Detailed Implementation

[0045] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise stated, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0046] The raw materials used in the following examples and comparative examples are as follows:

[0047] Ethylene-vinyl acetate copolymer (EVA):

[0048] EVA 1#: VA content is 33%; 150, Mitsui Chemicals, Japan.

[0049] EVA 2#: VA content is 28%; V6020M, Jiangsu Sirbang Company.

[0050] EVA 3#: VA content is 18.5%; V5110J, BASF Yangzi Company.

[0051] Thermoplastic polyurethane elastomer (TPU):

[0052] TPU 1#: WHT-1150, Wanhua Chemical Company.

[0053] TPU 2#: 3190A, Zhejiang Huafeng Company.

[0054] Polyvinyl acetate: S0105, Wacker Chemie Ltd., Japan.

[0055] Polyurethane resin: 627, Lihua Group, Taiwan, China.

[0056] LDPE: 1C7A, Yanshan Petrochemical Company.

[0057] Polypropylene (PP): MU4016, Yanshan Petrochemical Company.

[0058] Dispersant: Polyurethane; 330, Dongguan Ruishang Company.

[0059] Wetting agent: TEGO 410 (Germany).

[0060] Curing agent: AE808, Guangzhou AsiaInfo New Materials Co., Ltd.

[0061] Leveling agent: BYK-420, BYK GmbH, Germany.

[0062] Examples 1-3

[0063] This embodiment provides a series of EVA composite hot melt adhesives, the raw material components of which are shown in Table 1;

[0064] Table 1. Raw material components (parts by mass) for Examples 1-3

[0065]

[0066] The preparation method of the EVA composite hot melt adhesive includes the following steps:

[0067] S1. Add TPU particles to an appropriate amount of DMF, heat the mixing tank at 70℃ and stir for 40 minutes at a speed of 200 rpm to dissolve the particles into DMF to form a liquid, and then transfer it to a constant temperature tank at 60℃ for temporary storage to maintain stable liquid flow.

[0068] S2, add appropriate amounts of EVA and PP particles to toluene and methyl ethyl ketone, heat the stirring tank at 70°C and stir for 40 minutes at 230 rpm to dissolve the raw material particles in toluene and methyl ethyl ketone to form a liquid, and then transfer it to a constant temperature tank at 60°C for temporary storage to maintain stable liquid flow.

[0069] S3, adjust the temperature to 170℃ in the heating tank to mix and disperse LDPE with water in a molten state. Then, add it to the TPU material in step S1 and stir for 10 minutes to make it blended, thus obtaining a mixture.

[0070] S4. Add the mixture obtained in step S3 to the EVA / PP material obtained in step S2. Add the dispersing agent and stir at low speed for 30 minutes at 2500 rpm. Then add polyvinyl acetate, polyurethane resin, wetting agent and leveling agent, and stir at low speed for 60 minutes. In step S4, the temperature is controlled at 60℃ for all stirring processes. Then, the obtained hot melt adhesive paste is coated on the release film and dried to obtain EVA composite hot melt adhesive film.

[0071] Example 4

[0072] A 3D icon material for fabric heat transfer printing, made from the EVA composite hot melt adhesive film of Example 1, includes the following steps in its preparation process:

[0073] (1) A 3D pattern is printed on the EVA composite hot melt adhesive film using a UV printer. The ink used is Zhuhai Tianwei's soft UV curing ink. After printing, a PE protective film is placed on the surface to obtain the pattern adhesive film. The irradiation parameters are: 365nm wavelength and 25W single lamp power.

[0074] (2) After removing the release film on the bottom of the pattern film, it is attached to the textile fabric, which is pure cotton fabric. The pattern film is heat-pressed at 150°C for 2 seconds using a heat press machine, and the PE protective film on the top surface is torn off. At this time, the excess film around the pattern is transferred to the protective film, and the pattern is completely bonded to the fabric, thus obtaining a three-dimensional 3D icon material that is heat-transferred onto the fabric.

[0075] Products such as Figure 1-2 As shown, after a soap and water washing test at 40°C according to method A (1) of standard GB / T 3921-2008, it is not easy to stretch and break, and there is no fading.

[0076] Another sample was tested for color fastness to rubbing according to the method of standard GB / T 3920-2008; the results showed that the color fastness to dry rubbing was grade 3-4 and the color fastness to wet rubbing was grade 2-3.

[0077] Comparative Examples 1-3

[0078] This comparative example provides a series of EVA composite hot melt adhesives, with raw material components as shown in Table 2;

[0079] Table 2. Raw material composition (parts by mass) for Comparative Examples 1-3

[0080]

[0081] The preparation method of the EVA composite hot melt adhesive described in this comparative example is the same as that in the above embodiments.

[0082] Performance testing

[0083] 1. Mechanical property testing

[0084] The mechanical properties of the EVA composite hot melt adhesive materials of each embodiment and comparative example were tested, and the results are shown in Table 3.

[0085] Tensile strength: Tested according to the method of standard GB / T 30776-2014.

[0086] Peel strength: Tested according to the method of standard GB / T 2792-2014, the width of the test sample is 2.54cm.

[0087] Table 3

[0088]

[0089] The results show that the tensile strength of the EVA composite hot melt adhesive of the present invention is above 120 MPa and the peel force is greater than 40 N.

[0090] Compared to Example 1, the EVA composite hot melt adhesive of Comparative Example 1 uses EVA resin with a lower VA content, resulting in a decrease in its peel strength and tensile strength.

[0091] The hot melt adhesive in Comparative Example 2 does not contain TPU, and its tensile strength is significantly reduced.

[0092] The hot melt adhesive in Comparative Example 3 did not contain polyvinyl acetate, resulting in decreased peel strength and poor wash fastness of the prepared labels.

[0093] The above embodiments of the present invention are merely examples for clearly illustrating the present invention and are not intended to limit the implementation of the present invention. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively describe all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. An EVA composite hot melt glue, characterized in that, The EVA composite hot melt adhesive comprises the following components by mass fraction: thermoplastic polyurethane elastomer 15-25 parts, ethylene-vinyl acetate copolymer 30-50 parts, polyvinyl acetate 8-16 parts, film forming agent 2-10 parts, viscosity modifier 1-5 parts, polypropylene 0.1-2 parts; the VA content of the ethylene-vinyl acetate copolymer is ≥28wt%; the viscosity modifier is LDPE.

2. The EVA composite hot melt adhesive according to claim 1, characterized in that, the film forming agent is polyurethane resin and / or acrylic resin, the viscosity of the polyurethane resin at 25℃ is 4000-6000mpa.s.

3. The EVA composite hot melt adhesive according to claim 1, wherein, the VA content of the ethylene-vinyl acetate copolymer is 28-33wt%.

4. The EVA composite hot melt adhesive of claim 1, wherein, the melt flow rate of the ethylene-vinyl acetate copolymer at 190℃, 2.16kg is 1-40g / 10min.

5. The EVA composite hot melt adhesive of claim 1, wherein, the viscosity of the polyvinyl acetate at 25℃ is 1-4mpa.s.

6. The EVA composite hot melt adhesive of claim 1, wherein, the polypropylene is random copolymerized polypropylene.

7. The EVA composite hot melt adhesive of claim 1, wherein It also comprises: dispersant 1-3 parts, wetting agent 1-3 parts, curing agent 1-3 parts, leveling agent 0.5-2 parts.

8. A process for the preparation of the EVA compound hot melt adhesive as claimed in any one of claims 1 to 7, characterized by, It comprises the following steps: adding the raw materials in the formula amount into an organic solvent and stirring uniformly, the stirring temperature is 55-65℃, casting molding, to obtain the EVA composite hot melt adhesive.

9. Use of the EVA composite hot melt adhesive according to any one of claims 1-7 in the preparation of hot transfer three-dimensional icon materials.

10. A heat transfer three-dimensional icon material, characterized by, It is made of the EVA composite hot melt adhesive according to any one of claims 1-7.

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