Method for manufacturing arc-shaped print and arc-shaped print

Abstract

The application provides a preparation method of an arc-shaped print and the arc-shaped print, and relates to the technical field of printing. The preparation method of the arc-shaped print comprises the following steps: applying polyurethane paste on the surface of cloth through a screen, and performing surface drying to obtain a first coating layer; placing a hollow mold with a hollow flower site shape on the first coating layer and performing mold pressing to form a flower site coating layer, and performing drying to obtain the arc-shaped print; and the polyurethane paste contains a certain amount of ethanol. The preparation method can form the arc-shaped print at room temperature, and the process is simple and suitable for cloth sensitive to high temperature.

Description

Technical Field

[0001] This invention belongs to the field of printing technology, and relates to a method for preparing arc-shaped printing and the arc-shaped printing process. Background Technology

[0002] Limited by printing and forming processes, current fabric printing is mainly in the form of three-dimensional, angular shapes. To obtain arc-shaped three-dimensional prints, high-temperature molding or thick coating processes are generally required. High-temperature molding may adversely affect the printing performance at high temperatures and is not suitable for heat-sensitive fabrics. Thick coating processes require thick coating screens, but have high requirements for the size of the design pattern and the spacing between patterns, making it impossible to achieve coating printing with small spacing or small pattern designs.

[0003] Therefore, the existing arc-shaped printing process needs to be optimized and improved. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a method for preparing arc-shaped printing and an arc-shaped printing process.

[0005] The technical solution of the present invention is as follows:

[0006] A method for preparing an arc-shaped print includes the following steps: Polyurethane slurry is applied to the surface of the fabric through a screen and allowed to dry to obtain the first coating. A perforated mold with a perforated pattern is placed on the first coating and molded to form a pattern coating. After drying, the arc-shaped print is obtained. The raw material components of the polyurethane slurry include an aqueous polyurethane dispersion, a dispersant, a defoamer, a thickener, a thixotropic agent, ethanol, and a curing agent. The ethanol accounts for 1-5% of the weight of the polyurethane slurry.

[0007] Preferably, the polyurethane slurry has a thixotropic index of not less than 4 at 23°C and a viscosity of 100,000-200,000 cps at 23°C.

[0008] Preferably, the thixotropic agent is selected from at least one of microfiber, nano-calcium carbonate, and nano-silica.

[0009] Preferably, the thickness of the screen is 0.5-5mm; The height of the perforated mold is higher than the height of the screen.

[0010] More preferably, the height of the hollow mold is 2.5-7.5mm; The thickness between adjacent perforated areas of the perforated mold is 1-10mm.

[0011] Preferably, the surface tension of the perforated mold at 23°C does not exceed 30 mN / m or the roughness Ra of the perforated mold does not exceed 0.8 μm.

[0012] Preferably, the baking temperature for surface drying is 50-65℃.

[0013] Preferably, the molding is performed at room temperature and the pressure is 0.5-5 MPa.

[0014] Preferably, the drying temperature is 55-65℃ and the time is not less than 12 hours.

[0015] An arc-shaped print is prepared by the preparation method described in any of the above embodiments.

[0016] The beneficial effects of this invention are: (1) The present invention uses a hollow mold to mold the first coating on the surface, which avoids the first coating from sticking to the hollow mold. Moreover, the first coating is squeezed by the hollow mold and concentrated and expanded to the hollow part of the hollow mold. The squeezed part is concave and forms the edge (or gap) of the three-dimensional print. The expanded first coating forms an arc shape. After drying, a three-dimensional print with an arc shape can be obtained.

[0017] (2) The polyurethane slurry of the present invention contains a small amount of ethanol. Ethanol evaporates quickly and can inhibit the cross-linking reaction inside the slurry, which is conducive to the rapid formation of the first coating with surface drying and to maintaining good fluidity inside the first coating. It can form an arc-shaped three-dimensional printing under the extrusion of the stencil.

[0018] (3) This invention does not require high-temperature heating, the process is simple, and it is suitable for heat-sensitive fabrics. By adjusting the shape of the perforated mold and the thickness between adjacent perforated patterns, different spacing and different shapes of perforations can be obtained. Attached Figure Description

[0019] Figure 1 This is an image of the first coating in Example 1.

[0020] Figure 2 This is an image of the first coating being molded using a hollow mold in Example 1.

[0021] Figure 3 This is an image of the arc-shaped floral coating in Example 1. Detailed Implementation

[0022] The technical solution of the present invention will be further explained and described below through specific embodiments.

[0023] On the one hand, the present invention proposes a method for preparing arc-shaped printing, comprising the following steps: Polyurethane slurry is applied to the surface of the fabric through a screen and allowed to dry to obtain the first coating. A perforated mold with a perforated pattern is placed on the first coating and molded to form a pattern coating. After drying, an arc-shaped print is obtained. The raw material components of polyurethane slurry include aqueous polyurethane dispersion, dispersant, defoamer, thickener, thixotropic agent, ethanol and curing agent; The weight percentage of ethanol in polyurethane slurry is 1-5%.

[0024] Polyurethane slurry relies on a curing agent to crosslink and form a film. After being coated into a coating, it is cured by heating. The curing rates of the surface and the interior are relatively similar. When the coating becomes surface dry, the interior slurry also undergoes a certain degree of crosslinking reaction, and the interior slurry has poor fluidity. The polyurethane slurry of the present invention contains a certain amount of ethanol (e.g., 1%, 2%, 3%, 4% or 5%), and has the following characteristics: (1) Ethanol is easy to evaporate and will not affect the crosslinking reaction on the surface of the coating. The surface of the polyurethane slurry can quickly crosslink and form surface dryness. (2) The ethanol inside the slurry can react with the isocyanate curing agent to inhibit the crosslinking reaction. Therefore, the slurry inside the first coating that is surface dry still has good fluidity. Under the molding of the stencil, the first coating forms a depression at the extrusion point (extrusion of the mold wall of the stencil). The extruded slurry concentrates towards the stencil position and increases in thickness, forming a three-dimensional print. Due to the extrusion action and surface dryness, the surface of the three-dimensional print is arc-shaped and will not form three-dimensional edges. After the final drying step, a three-dimensional print with an arc shape can be obtained.

[0025] Too much or too little ethanol in the aforementioned polyurethane paste is detrimental to the formation of arc-shaped 3D printing. Excessive ethanol affects the stability of the polyurethane paste, or causes it to evaporate too quickly, resulting in a thin surface-dried layer that is prone to cracking under the pressure of the die, leading to the leakage of the more fluid paste and affecting the coating effect. Insufficient ethanol results in slow surface drying, causing some curing reaction in the internal paste after surface drying, leading to poor internal paste fluidity. Even with the pressure of the die, the first coating will struggle to form an arc-shaped 3D print. Furthermore, the weight percentage of ethanol in the polyurethane paste should be 1-3%.

[0026] In this invention, the stencil can be removed after the pattern coating is formed, or it can be removed after the pattern coating dries to form an arc-shaped print.

[0027] In some embodiments, the thixotropic index of the polyurethane slurry at 23°C is not less than 4, and the viscosity at 23°C is 100,000-200,000 cps.

[0028] Polyurethane pastes have a high thixotropic index, which is more conducive to forming arc-shaped three-dimensional printing. For example, the thixotropic index of polyurethane pastes can be 4, 4.5, 5, 5.5, 6, etc. The viscosity η1 at 7.5 rpm and the viscosity η2 at 75 rpm are measured using a rotational viscometer. The thixotropic index = η1 / η2.

[0029] In some embodiments, the thixotropic agent is selected from at least one of microfiber, nano-calcium carbonate, and nano-silica. Microfiber, nano-calcium carbonate, and nano-silica, as thixotropic agents, exhibit good thixotropic properties. For example, the weight percentage of microfiber in the polyurethane slurry can be 3-5%, the weight percentage of nano-calcium carbonate in the polyurethane slurry can be 5-10%, and the weight percentage of nano-silica in the polyurethane slurry can be 0.5-3%. The microfiber can be fine fiber powder obtained from crushed polyester fabric, with an average particle size of 50-250 μm, which improves the thixotropic properties of the polyurethane slurry while avoiding excessive viscosity.

[0030] In this invention, there are no particular limitations on the dispersant, defoamer, thickener, and curing agent. For example, the dispersant can be a polymeric dispersant, the defoamer can be dimethyl silicone oil, the thickener can be a nonionic polyurethane associative thickener, and the curing agent can be an aqueous isocyanate curing agent.

[0031] In some embodiments, the thickness of the screen is 0.5-5mm; The height of the stencil is higher than the height of the screen.

[0032] The thickness of the screen determines the thickness of the first coating. In this invention, to create a three-dimensional printing effect, the screen thickness should not be too thin. For example, the screen thickness can be 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, etc.

[0033] The height of the stencil is higher than the height of the screen to prevent the first coating from overflowing after being squeezed. For example, the height of the stencil can be 1mm, 5mm, or 10mm higher than the height of the screen.

[0034] In some embodiments, the height of the cutout mold is 2.5-7.5mm; The thickness between adjacent perforated areas of the perforated mold is 1-10mm.

[0035] For example, the height of the cutout mold can be 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, etc.

[0036] The thickness between adjacent perforated areas of a cutout mold is equivalent to the wall thickness of those adjacent perforated areas, which is the part that compresses the first coating layer. If the thickness between adjacent perforated areas is too thin, the amount of compression of the first coating layer is too small, resulting in an indistinct arc-shaped print. If the thickness between adjacent perforated areas is too large, the amount of compression is too large, requiring a larger perforated area size. For example, the thickness between adjacent perforated areas of a cutout mold can be 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, etc.

[0037] In some embodiments, the surface tension of the cutout mold at 23°C does not exceed 30 mN / m or the roughness Ra of the cutout mold does not exceed 0.8 μm.

[0038] The low surface tension or smooth surface of the cutout mold can further reduce the adhesion to the first coating. For example, the cutout mold can be made of a low surface energy polymer material, such as polyethylene, polypropylene, or polytetrafluoroethylene, or a smooth metal, such as stainless steel or aluminum alloy, or a metal surface coated with a low surface energy coating.

[0039] In some embodiments, the surface drying temperature is 50-65°C. A surface drying temperature of 50-65°C is suitable for achieving a suitable surface drying speed. Specifically, the drying can be carried out in a forced-air drying oven, a tunnel heating furnace, or a mobile drying oven.

[0040] In some embodiments, molding is performed at room temperature under a pressure of 0.5-5 MPa. In this invention, molding is used to form arc-shaped three-dimensional prints, which do not require heating and can be performed directly at room temperature. The pressure also does not need to be too high; 0.5-5 MPa is sufficient, or even 1-5 MPa.

[0041] In some embodiments, the drying temperature is 55-65°C, and the drying time is not less than 12 hours. The drying temperature and drying time are adjusted according to the thickness of the 3D printed coating. The thicker the coating, the longer the drying time is generally required, such as 24 hours or 36 hours, to achieve complete drying. As drying progresses, the ethanol inside the arc-shaped 3D print gradually evaporates, and the curing agent and water-based polyurethane undergo a cross-linking reaction, completing the drying process of the coating.

[0042] On the other hand, the present invention also proposes an arc-shaped print, which is prepared by the preparation method described in any of the above embodiments.

[0043] The technical solution of the present invention will be further described and illustrated below with reference to various embodiments. Unless otherwise specified, the parts mentioned in the following embodiments are parts by weight.

[0044] Example 1 The polyurethane slurry, by weight, consists of 0.8% dispersant BYK190, 0.5% dimethyl silicone oil defoamer, 3% microfiber, 7% nano-calcium carbonate, 2% nano-silica, 2% nonionic polyurethane associative thickener, 5% waterborne isocyanate curing agent, 3% ethanol, and the balance being a waterborne polyurethane dispersion. The thixotropic index of the polyurethane slurry was measured to be 5.5.

[0045] Polyurethane paste was printed onto the surface of the fabric using a 2mm thick screen printing plate. The mixture was then heated in a 62℃ forced-air drying oven for 3 minutes to obtain the first coating, which was surface-dried. The first coating is shown in the attached image. Figure 1 As shown.

[0046] The hollow mold has hollowed-out patterns and is made of stainless steel with a surface coated with polytetrafluoroethylene. The thickness between adjacent hollowed-out patterns is 2mm and the height is 4mm.

[0047] The perforated mold is placed on the first coating layer and pressure of 2MPa is applied for molding, as shown in the attached figure. Figure 2 As shown, an arc-shaped patterned coating is formed, as attached. Figure 3 As shown, remove the perforated mold, dry, and obtain an arc-shaped print.

[0048] Example 2 The polyurethane slurry, by weight, consists of 0.6% dispersant BYK190, 0.4% dimethyl silicone oil defoamer, 4% microfiber, 10% nano-calcium carbonate, 1.5% nano-silica, 1.5% nonionic polyurethane associative thickener, 5% waterborne isocyanate curing agent, 1% ethanol, and the balance being a waterborne polyurethane dispersion. The thixotropic index of the polyurethane slurry was measured to be 4.2.

[0049] Polyurethane paste is printed onto the surface of the fabric using a 1mm thick screen printing plate. The fabric is then heated in a 60℃ forced-air drying oven for 4 minutes to obtain the first coating, which is surface dry.

[0050] The perforated mold has a perforated pattern shape and is made of stainless steel with a surface coated with polytetrafluoroethylene. The thickness between adjacent perforated patterns is 1.5mm and the height is 2mm.

[0051] The stencil is placed on the first coating layer and pressurized at 3MPa to form an arc-shaped pattern coating. The stencil is then removed and the mixture is dried to obtain an arc-shaped print.

[0052] Example 3 The polyurethane slurry, by weight, consists of 0.6% dispersant BYK190, 0.4% dimethyl silicone oil defoamer, 5% microfiber, 10% nano-calcium carbonate, 2.5% nano-silica, 2.5% nonionic polyurethane associative thickener, 6% waterborne isocyanate curing agent, 5% ethanol, and the balance being a waterborne polyurethane dispersion. The thixotropic index of the polyurethane slurry was measured to be 4.6.

[0053] Polyurethane paste is printed onto the surface of the fabric using a screen with a thickness of 4 mm. The fabric is then heated in a 65°C forced-air drying oven for 5 minutes to obtain the first coating, which is surface dry.

[0054] The perforated mold has perforated flower shapes and is made of stainless steel with a surface coated with polytetrafluoroethylene. The thickness between adjacent perforated flower shapes is 3mm and the height is 7mm.

[0055] The stencil is placed on the first coating layer and pressurized at 4MPa to form an arc-shaped pattern coating. The stencil is then removed and the mixture is dried to obtain an arc-shaped print.

[0056] As described above, the basic principles, main features, and advantages of the present invention have been shown and described. Those skilled in the art should understand that the present invention is not limited to the above embodiments, which are merely preferred embodiments and should not be construed as limiting the scope of the invention. All equivalent changes and modifications made in accordance with the scope of the patent and the description should still fall within the scope of the present invention. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an arc-shaped print, characterized in that, Includes the following steps: Polyurethane slurry is applied to the surface of the fabric through a screen and allowed to dry to obtain the first coating. A perforated mold with a perforated pattern is placed on the first coating and molded to form a pattern coating. After drying, the arc-shaped print is obtained. The raw material components of the polyurethane slurry include an aqueous polyurethane dispersion, a dispersant, a defoamer, a thickener, a thixotropic agent, ethanol, and a curing agent. The ethanol accounts for 1-5% of the weight of the polyurethane slurry.

2. The method for preparing arc-shaped printing according to claim 1, characterized in that, The polyurethane slurry has a thixotropic index of not less than 4 at 23°C and a viscosity of 100,000-200,000 cps at 23°C.

3. The method for preparing arc-shaped printing according to claim 1, characterized in that, The thixotropic agent is selected from at least one of microfiber, nano-calcium carbonate, and nano-silica.

4. The method for preparing arc-shaped printing according to claim 1, characterized in that, The thickness of the screen is 0.5-5mm; The height of the perforated mold is higher than the height of the screen.

5. The method for preparing arc-shaped printing according to claim 4, characterized in that, The height of the hollow mold is 2.5-7.5mm; The thickness between adjacent perforated areas of the perforated mold is 1-10mm.

6. The method for preparing arc-shaped printing according to claim 1, characterized in that, The surface tension of the hollow mold at 23°C does not exceed 30 mN / m or the roughness Ra of the hollow mold does not exceed 0.8 μm.

7. The method for preparing arc-shaped printing according to claim 1, characterized in that, The baking temperature for the surface drying process is 50-65℃.

8. The method for preparing arc-shaped printing according to claim 1, characterized in that, The molding is performed at room temperature and at a pressure of 0.5-5 MPa.

9. The method for preparing arc-shaped printing according to claim 1, characterized in that, The drying temperature is 55-65℃, and the time is not less than 12 hours.

10. An arc-shaped printing method, characterized in that, It is prepared by the preparation method according to any one of claims 1-9.

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