EVA (Ethylene Vinyl Acetate) composite hot melt adhesive for UV (Ultraviolet) printing of three-dimensional icons as well as preparation method and application thereof

Abstract

The invention discloses an EVA (Ethylene Vinyl Acetate) composite hot melt adhesive for UV (Ultraviolet) printing of a three-dimensional icon as well as a preparation method and application thereof. The EVA composite hot melt adhesive comprises a thermoplastic polyurethane elastomer, an ethylene-vinyl acetate copolymer, polyvinyl acetate, a film-forming agent, a viscosity modifier and polypropylene; the VA content of the ethylene-vinyl acetate copolymer is greater than or equal to 28wt%. According to the EVA composite hot melt adhesive disclosed by the invention, EVA with relatively high VA content is adopted as a matrix, and TPU is added for compounding, so that the stretching effect of a material is improved, the hydrophilicity of the EVA can be improved, and the washing fastness of the EVA after hot pressing and film forming is enhanced; by adding the polyacetic acid, the cohesiveness of the material can be improved, and meanwhile, the washing fastness of the material is improved. Through the synergistic effect of all the components, the material achieves the effects of good tensile property and washing resistance, and a wear-resistant and washing-resistant three-dimensional icon can be formed on a textile fabric.

Description

Technical Field

[0001] The invention belongs to the technical field of printing materials, and in particular relates to an EVA composite hot melt adhesive for UV printing of three-dimensional icons, and a preparation method and application thereof. Background Art

[0002] At present, the printing on fabric is mainly flat structure, while 3D color vertical logo printing can not only form a variety of patterns, but also increase the touch of textiles and rich visual effects, which is deeply loved by consumers. Foam printing can print the resin coating paste containing foaming agent on the fabric, and then after high-temperature steaming, the printed pattern will bubble up and present a relief effect; however, the mechanical properties of the foaming material are poor, it is easy to deform, and the water washing resistance is poor.

[0003] The existing processes for printing 3D color icons on fabrics include: screen printing, lettering film process and silicone embossing. However, the above printing processes are relatively complex and require huge equipment investment. Taking the screen printing process as an example, if you want to make a 3D color icon, you need to make a plate and adjust the color. In the lettering film or silicone process, you need to scrape the color, bake, cut the required graphics or icons with a laser, and then manually remove the excess waste and emboss. The above color icon production processes are complex, the cost is very high, and the output is very low, so it is very rare to print color 3D icons on fabrics.

[0004] UV printing technology mainly refers to the use of special UV ink on a UV printing machine to achieve partial or overall UV printing effects. It is a full-color digital printing process without plate making. It is not restricted by materials and can perform color photo-level printing on surfaces such as T-shirts, glass, plates, plastics, stones, and leather. It does not require plate making and can be printed in one go. It has bright and rich colors, is wear-resistant, and UV-resistant. It is easy to operate and prints images quickly. Compared with traditional offset printing, UV printing has the advantages of bright colors, simple and fast production process, and broad market prospects. However, the existing UV printed products have low tensile strength and are easy to tear and deform, which limits their application in printing color stereoscopic 3D icons on fabrics.

[0005] Patent CN108728017A proposes a hot melt adhesive for fabric and a preparation method thereof. The hot melt adhesive includes an EVA matrix resin, a tackifier, a viscosity regulator, a filler and a cross-linking agent, and is prepared by a method combining melt blending and light irradiation. The prepared hot melt adhesive has good heat resistance and crack resistance; however, the hot melt adhesive fails to solve the problem of poor water washing fastness of EVA materials. Summary of the invention

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

[0007] Another object of the present invention is to provide a method for preparing an 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 thermal transfer three-dimensional icon materials.

[0009] Another object of the present invention is to provide a thermal transfer three-dimensional icon material.

[0010] The above-mentioned purpose of the present invention is achieved through the following technical solutions: The present invention protects an EVA composite hot melt adhesive, characterized in that it comprises the following components in parts by mass: Thermoplastic polyurethane elastomer 15-25 parts, 30-50 parts of ethylene-vinyl acetate copolymer, 8-16 parts of polyvinyl acetate, Film former 2-10 parts, 1-5 parts of viscosity modifier, Polypropylene 0.1-2 parts; The VA content of the ethylene-vinyl acetate copolymer is ≥28wt%.

[0011] The EVA composite hot melt adhesive of the present invention adopts ethylene-vinyl acetate copolymer (EVA) with a relatively high VA content as a matrix, and is compounded with a thermoplastic polyurethane elastomer (TPU), so as to improve the ductility and stretching effect of the material, improve the hydrophilicity of the EVA, and enhance the water washing fastness of the EVA after hot pressing and film formation; the addition of polyacetic acid can improve the adhesion of the material and simultaneously improve the water washing fastness of the material; through the synergistic effect of each component, the material achieves the effects of good stretching performance and water washing resistance.

[0012] In addition, a specific amount of polypropylene is added to the EVA composite hot melt adhesive of the present invention, which can improve the hardness of the material and the shearing property of the film, is beneficial to the waste discharge after the thermal transfer process, and the adhesive film is not easy to be drawn and left.

[0013] It should be noted that the present invention needs to control 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 defect of poor water resistance of EVA, and improve the water washing fastness of the material.

[0014] 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 the tensile strength of polyurethane resin is more prominent, which is beneficial to improving the tensile effect of the product.

[0015] Preferably, the polyurethane resin has a viscosity of 4000-6000 mPa.s at 25°C.

[0016] 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.

[0017] In some embodiments, the viscosity modifier is LDPE; LDPE has good fluidity, can solve the flow effect of liquid during coating, and has good high temperature resistance and is not easy to precipitate at high temperature.

[0018] In some embodiments, the VA content of the ethylene-vinyl acetate copolymer is ≥30 wt %. Preferably, the VA content of the ethylene-vinyl acetate copolymer is 30-50 wt %.

[0019] In some embodiments, the ethylene-vinyl acetate copolymer has a melt flow rate of 1-40 g / 10 min, preferably 5-35 g / 10 min, at 190° C. and 2.16 kg.

[0020] 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, more preferably metallocene random copolymer polypropylene.

[0021] In some embodiments, the following components are included in parts by weight: Thermoplastic polyurethane elastomer 18-22 parts, 35-45 parts of ethylene-vinyl acetate copolymer, 3-8 parts of polyvinyl acetate, Film former 10-14 parts, 1-3 parts of viscosity modifier, Polypropylene 0.5-1.5 parts.

[0022] 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.

[0023] A preparation method of an EVA composite hot melt adhesive comprises the following steps: adding a formulated amount of raw materials into an organic solvent and stirring evenly at a stirring temperature of 55-65° C., and performing tape casting to obtain the EVA composite hot melt adhesive.

[0024] It should be noted that in the preparation method of the present invention, the heating temperature needs to be controlled within a specific range. If the temperature is too high, crystallization is likely to occur, and if the temperature is too low, agglomeration is likely to occur.

[0025] The invention discloses an application of an EVA composite hot melt adhesive in preparing UV printed three-dimensional icons.

[0026] A UV printed three-dimensional icon material, which is made of EVA composite hot melt adhesive through UV printing. Compared with the prior art, the present invention has the following beneficial effects: The present invention provides an EVA composite hot melt adhesive, which uses an EVA resin with a high VA content as a matrix, adds TPU to improve the ductility and stretching effect of the material after film formation, and can also improve the hydrophilicity of EVA and enhance its water washing fastness after hot pressing film formation; adding polyacetic acid can improve the adhesion of the material and improve the water washing fastness of the material. Through the synergistic effect of each component, the effects of good tensile performance and good water washing resistance are achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a physical picture of the 3D stereo icon material thermally transferred from fabric according to Example 4 of the present invention.

[0028] Figure 2 The present invention Figure 1 Actual picture of the product in stretched state after washing. DETAILED DESCRIPTION

[0029] The present invention is further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0030] The raw materials used in the following examples and comparative examples are as follows: Ethylene-vinyl acetate copolymer (EVA): EVA 1#: VA content is 33%; 150, Mitsui Chemicals, Japan.

[0031] EVA 2#: VA content is 28%; V6020M, Jiangsu Sailbon Company.

[0032] EVA 3#: VA content is 18.5%; V5110J, BASF-Yangzi Company.

[0033] Thermoplastic polyurethane elastomer (TPU): TPU 1#: WHT-1150, Wanhua Chemical Company.

[0034] TPU 2#: 3190A, Zhejiang Huafeng Company.

[0035] Polyvinyl acetate: S0105, Wacker, Japan.

[0036] Polyurethane resin: 627, Lihua Group, Taiwan, China.

[0037] LDPE: 1C7A, Yanshan Petrochemical Company.

[0038] Polypropylene (PP): MU4016, Yanshan Petrochemical Company.

[0039] Dispersant: polyurethane; 330, Dongguan Ruishang Company.

[0040] Wetting agent: TEGO 410 from Germany.

[0041] Curing agent: AE808, Guangzhou Yaxin New Materials Co., Ltd.

[0042] Leveling agent: BYK-420, BYK, Germany.

[0043] Examples 1-3 This embodiment provides a series of EVA composite hot melt adhesives, the raw material components include those shown in Table 1; Table 1 Raw material components of Examples 1-3 (parts by mass)

[0044] The preparation method of the EVA composite hot melt adhesive comprises the following steps: S1, add TPU particles into an appropriate amount of DMF, heat the stirring barrel at 70°C and stir for 40 minutes at a speed of 200 rpm to make the particles melt in DMF to form a liquid, and then transfer to a 60°C constant temperature barrel for temporary storage to maintain stable liquid fluidity; S2, adding appropriate amount of toluene and butanone to EVA particles and PP particles, stirring in a stirring barrel heated at 70°C for 40 minutes at a speed of 230 rpm, so that the raw material particles are melted in toluene and butanone to form a liquid, and then transferred from a 60°C constant temperature barrel for temporary storage to maintain stable liquid fluidity; S3, adjusting the temperature to 170° C. in a heating barrel, mixing and evenly dispersing the LDPE with water in a molten state, and introducing the LDPE into the TPU material of step S1 and stirring for 10 minutes to make them blend, thereby obtaining a mixed material; S4, adding the mixed material obtained in step S3 to the EVA / PP material obtained in step S2, adding a dispersing aid and stirring at a low speed of 2500 rpm for 30 minutes, then adding polyvinyl acetate, polyurethane resin, wetting agent and leveling agent, stirring at a low speed for 60 minutes, and all stirring processes in step S4 are controlled to maintain the temperature at 60°C, then coating the obtained hot melt adhesive slurry on a release film, and drying to obtain an EVA composite hot melt adhesive film.

[0045] Example 4 A 3D stereoscopic icon material for thermal transfer of fabric is made of the EVA composite hot melt adhesive film of Example 1, and its preparation process comprises the following steps: (1) Printing a 3D pattern on the EVA composite hot melt adhesive film by a UV printer, using soft UV curing ink from Zhuhai Tianwei. After printing, a PE protective film is covered on the surface to obtain a pattern adhesive film. The irradiation parameters are: band 365nm, single lamp power 25W.

[0046] (2) After removing the release film on the bottom surface of the patterned adhesive film, the patterned adhesive film is attached to a textile fabric, which is pure cotton fabric. The patterned adhesive film is heat-pressed at 150°C for 2s using a pressing machine, and the PE protective film on the upper surface is torn off. At this time, the excess adhesive film around the pattern is transferred to the protective film, and the pattern is completely bonded to the fabric, thereby obtaining a three-dimensional 3D icon material that is heat-transferred to the fabric.

[0047] Products such as Figure 1-2 As shown, after washing with soapy water at 40°C according to the method A (1) of standard GB / T 3921-2008, it is not easy to be stretched and broken, and there is no fading.

[0048] Another sample was taken to test the color fastness to rubbing according to the method of standard GB / T 3920-2008; the results showed that the color fastness to dry rubbing of the sample was level 3-4, and the color fastness to wet rubbing was level 2-3.

[0049] Comparative Examples 1-3 This comparative example provides a series of EVA composite hot melt adhesives, the raw material components include those shown in Table 2; Table 2 Raw material components of comparative examples 1-3 (parts by mass)

[0050] The preparation method of the EVA composite hot melt adhesive in this comparative example is the same as that in the above embodiment.

[0051] Performance Testing 1. Mechanical properties test The mechanical properties of the EVA composite hot melt adhesive materials of the embodiments and comparative examples were tested, and the results are shown in Table 3.

[0052] Tensile strength: Tested according to the method of standard GB / T 30776-2014.

[0053] Peel force: tested according to the method of standard GB / T 2792-2014, the width of the test sample is 2.54cm.

[0054] Table 3

[0055] The results show that the tensile strength of the EVA composite hot melt adhesive of the present invention is above 120 MPa, and the peeling force is greater than 40N.

[0056] Compared with Example 1, the EVA composite hot melt adhesive of Comparative Example 1 uses an EVA resin with a lower VA content, and its peel strength and tensile strength are reduced.

[0057] The hot melt adhesive of Comparative Example 2 does not contain TPU, and its tensile strength is significantly reduced.

[0058] The hot melt adhesive of Comparative Example 3 does not contain polyvinyl acetate, and its peel strength is reduced, and the prepared label has poor water washing fastness.

[0059] The above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. An EVA composite hot melt adhesive, characterized in that: The composition includes the following components in parts by weight: Thermoplastic polyurethane elastomer 15-25 parts, 30-50 parts of ethylene-vinyl acetate copolymer, 8-16 parts of polyvinyl acetate, Film former 2-10 parts, 1-5 parts of viscosity modifier, Polypropylene 0.1-2 parts; The VA content of the ethylene-vinyl acetate copolymer is ≥28wt%.

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.

3. The EVA composite hot melt adhesive according to claim 1, characterized in that: The viscosity modifier is LDPE.

4. The EVA composite hot melt adhesive according to claim 1, characterized in that: The ethylene-vinyl acetate copolymer has a melt flow rate of 1-40 g / 10 min at 190° C. and 2.16 kg.

5. The EVA composite hot melt adhesive according to claim 1, characterized in that: The polyvinyl acetate has a viscosity of 1-4 mPa.s at 25°C.

6. The EVA composite hot melt adhesive according to claim 1, characterized in that: The polypropylene is random copolymer polypropylene.

7. The EVA composite hot melt adhesive according to claim 1, characterized in that: Also includes: Dispersant 1-3 parts, wetting agent 1-3 parts, curing agent 1-3 parts, leveling agent 0.5-2 parts.

8. A method for preparing the EVA composite hot melt adhesive according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: adding a formulated amount of raw materials into an organic solvent and stirring evenly at a stirring temperature of 55-65° C., and performing tape casting to obtain the EVA composite hot melt adhesive.

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

10. A thermal transfer three-dimensional icon material, characterized in that: It is made of the EVA composite hot melt adhesive described in any one of claims 1 to 7.

Images