A polyurethane shoe sole film forming process

Abstract

A polyurethane shoe sole coating molding process includes the following steps: Step 1, preparing a polyurethane composition, casting it into a film, curing it at 40-70℃, with the curing degree not exceeding 75% of the overall complete curing degree, then spraying ink on its surface to form an ink pattern, and then curing it with ultraviolet light to obtain a GPU film; Step 2, placing the polyurethane shoe sole on a vacuum platform; Step 3, turning on the vacuum to adsorb the GPU film onto the polyurethane shoe sole, obtaining a semi-finished polyurethane shoe sole; Step 4, placing the semi-finished polyurethane shoe sole into a pressing mold and pressing it for 5-15 seconds to obtain a pressed polyurethane shoe sole; Step 5, placing the pressed polyurethane shoe sole into a constant temperature oven to allow the GPU film to be cured a second time, and leaving it at room temperature for 24 hours to obtain the coated polyurethane shoe sole. The molding method of the GPU film is limited, and it is cured twice to completely cure and coat the polyurethane shoe sole, so that the shoe sole performance is stable.

Description

Technical Field

[0001] This invention belongs to the field of shoe sole manufacturing, specifically relating to a polyurethane shoe sole coating molding process. Background Technology

[0002] PU (polyurethane) soles possess advantages that other materials cannot match, such as low density, good elasticity, good compression ratio, resistance to deformation, and good dimensional stability. They are mainly divided into two categories: one type is produced by foaming liquid raw materials through a chemical reaction, generally using a two-component liquid reaction molding process for polyurethane. The main chemical reactions in this process include exothermic gelation, endothermic foaming, and cross-linking. Soles produced using this method have simple decorations and limited colors, failing to meet today's demand for technological content and highlights. The other type is ETPU (commonly known as "popcorn"), which is made by supercritical foaming of thermoplastic polyurethane to obtain expanded thermoplastic polyurethane beads, followed by steam molding. However, gaps easily appear between the beads, resembling mouse holes, resulting in poor tear resistance and even sole breakage. Designers often use a structure design with a rubber sole, which significantly increases the weight of the entire sole, contradicting the initial design goal of lightweight construction.

[0003] Printed soles are created by transferring or spraying patterns or colors onto the outside of the sole, making it more aesthetically pleasing and meeting people's pursuit of a high-quality lifestyle. However, printed soles made using spraying techniques are most prone to color fading due to frequent friction with the ground, and this requires further improvement. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a polyurethane shoe sole coating molding process.

[0005] The present invention adopts the following technical solution:

[0006] A polyurethane shoe sole coating molding process includes the following steps:

[0007] Step 1: Prepare a polyurethane composition, cast it into a film, and cure it at 40-70℃. The degree of curing shall not exceed 75% of the total complete curing degree. Then, spray ink on its surface to form an ink pattern, and then cure it with ultraviolet light to obtain a GPU film with a thickness of 0.3-3mm.

[0008] Step 2: Place the polyurethane sole on the vacuum platform with the bottom facing up, and then raise the vacuum platform.

[0009] Step 3: Start vacuuming to adsorb the preheated GPU film onto the polyurethane sole. After stabilizing for 8-30 seconds, stop vacuuming and lower the vacuuming platform to obtain the semi-finished polyurethane sole.

[0010] Step 4: Place the semi-finished polyurethane sole into the pressing mold and press it with the pressing machine for 5-15 seconds to obtain the pressed polyurethane sole.

[0011] Step 5: Place the pressed polyurethane sole into a constant temperature oven to allow the GPU film to cure a second time. After cooling at room temperature, trim and finish the edges to obtain the coated polyurethane sole.

[0012] Furthermore, in step five, the temperature for secondary curing is 40-70℃, and the curing time is 0.5-5h.

[0013] Furthermore, in step three, the GPU film preheating temperature is 100-200℃.

[0014] Furthermore, in step three, the vacuum level is below 0.1 mbar during the evacuation process.

[0015] Furthermore, the polyurethane composition is composed of component A and component B in a volume ratio of 100:60-90. Component A includes the following raw materials in parts by weight: 100 parts of polyol prepolymer, 7-13 parts of chain extender, 0.5-3 parts of silica, 0.1-0.2 parts of catalyst, 0.3-1 parts of hydroxyethyl acrylate, and 0.005-0.01 parts of photoinitiator.

[0016] Furthermore, the ink is a UV ink.

[0017] Furthermore, the viscosity of the polyol prepolymer is 400-1000cp, the hydroxyl content is 45-68mKOH / g, the acid value is less than 0.5mgKOH / g, and the moisture content is less than 1000ppm.

[0018] Furthermore, the polyol prepolymer includes at least one of polyester polyol and polyether polyol.

[0019] Furthermore, the B material is an isocyanate prepolymer with an isocyanate content of 14-35%.

[0020] Furthermore, the isocyanate prepolymer includes at least one of diisocyanate-modified polyester polyol prepolymer and diisocyanate-modified polyether polyol prepolymer.

[0021] As can be seen from the above description of the present invention, compared with the prior art, the beneficial effects of the present invention are as follows: This application sprays a UV pattern onto an incompletely cured polyurethane film, cures it with ultraviolet light to form a GPU film, and then combines it with a polyurethane shoe sole to give the polyurethane shoe sole different colors and patterns, improve the aesthetics of the polyurethane shoe sole, and protect the polyurethane shoe sole, prevent the sole from breaking, and improve wear resistance and anti-slip performance; at the same time, the forming method of the GPU film is limited, and it is cured twice to completely cure and cover the polyurethane shoe sole, so that the shoe sole performance is stable, which solves the problem of poor tear performance or even sole breakage of polyurethane shoe soles formed by foaming and molding polyurethane beads. Moreover, the finished shoe sole can be shipped within 24 hours, which greatly shortens the storage time, increases the turnover time, and thus improves production efficiency.

[0022] By defining the specific composition of the polyurethane composition, hydroxyethyl acrylate and a photoinitiator are added to component A, and then UV ink sprayed on its surface is used. After UV curing, they can be stably bonded, allowing the ink pattern to adhere stably to the GPU film. The ink pattern will not deform when heated, and it has good adhesion to the polyurethane sole, thereby ensuring the overall performance of the finished sole. Attached Figure Description

[0023] Figure 1 A molding device for polyurethane shoe sole coating;

[0024] Figure 2 A structural diagram of a coated polyurethane shoe sole;

[0025] Figure 3 An exploded view of a coated polyurethane sole;

[0026] 1-Polyurethane sole, 2-GPU membrane, 3-Vacuum platform. Detailed Implementation

[0027] The present invention will be further described below through specific embodiments.

[0028] A polyurethane shoe sole coating molding process includes the following steps:

[0029] Step 1: Prepare a polyurethane composition, cast it into a film, and cure it at 40-70℃. The degree of curing shall not exceed 75% of the total degree of curing. Then, spray UV ink on its surface to form an ink pattern, and then cure it with UV light to obtain a GPU film 2 with a thickness of 0.3-3mm.

[0030] Step 2: Place the polyurethane sole 1 onto the vacuum platform 3 with the bottom facing up, and then raise the vacuum platform 3.

[0031] Step 3: Start vacuuming, adsorb the preheated GPU film 2 onto the polyurethane sole 1, stabilize for 8-30 seconds, then stop vacuuming, and the vacuuming platform 3 descends to obtain the semi-finished polyurethane sole.

[0032] Step 4: Place the semi-finished polyurethane sole into the pressing mold and press it with the pressing machine for 5-15 seconds to obtain the pressed polyurethane sole.

[0033] Step 5: Place the pressed polyurethane sole in a constant temperature oven and cure it at 40-70℃ for 0.5-5 hours to allow the GPU film 2 to cure a second time. After cooling at room temperature, trim and finish to obtain the coated polyurethane sole.

[0034] In step three, the GPU film 2 is preheated at 100-200℃; during vacuuming, the vacuum level is below 0.1mbar.

[0035] Polyurethane shoe soles 1 include one or more of polyester polyurethane, polyether polyurethane, and aliphatic polyurethane according to material type; and one of ETPU (expanded thermoplastic polyurethane) shoe soles, thermoplastic polyurethane shoe soles, and cast polyurethane foam shoe soles according to molding process; specifically, polyurethane shoe soles are preferably polyurethane shoe soles formed by foaming and molding polyurethane beads.

[0036] The polyurethane composition consists of component A and component B in a volume ratio of 100:60-90.

[0037] Material A comprises the following raw materials in parts by weight: 100 parts polyol prepolymer, 7-13 parts chain extender, 0.5-3 parts silica, 0.1-0.2 parts catalyst, 0.3-1 part hydroxyethyl acrylate, and 0.005-0.01 parts photoinitiator; specifically, the polyol prepolymer has a viscosity of 400-1000 cp (at 75℃), hydroxyl groups of 45-68 mgKOH / g, an acid value of less than 0.5 mgKOH / g, and a moisture content of 1000%. Within ppm; furthermore, the polyol prepolymer includes at least one of polyester polyol and polyether polyol, wherein the polyester polyol is one or more of polybutylene adipate polyol, polyethylene adipate polyol, polyethylene adipate-propylene glycol ester, polyethylene adipate-diethylene glycol ester, polycaprolactone polyol and polycarbonate diol; and the polyether polyol is one or more of polypropylene glycol, polytetrahydrofuran diol, and tetrahydrofuran-propylene oxide copolyol.

[0038] Material B is an isocyanate prepolymer with an isocyanate content of 14-35%. Specifically, the isocyanate prepolymer includes at least one of diisocyanate-modified polyester polyol prepolymer and diisocyanate-modified polyether polyol prepolymer. Further, the isocyanate prepolymer is a diphenylmethane diisocyanate (MDI)-modified polyester polyol prepolymer.

[0039] By defining the specific composition of the polyurethane composition, hydroxyethyl acrylate and a photoinitiator are added to component A, and then UV ink sprayed on its surface is used. After UV curing, they can be stably bonded, so that the ink pattern is stably attached to the GPU film 2. The ink pattern will not deform when heated, and it has good adhesion to the polyurethane sole, thereby ensuring the overall performance of the finished sole.

[0040] Example 1

[0041] A polyurethane shoe sole coating molding process includes the following steps:

[0042] Step 1: Prepare a polyurethane composition, cast it into a film, cure it at 40°C, and cure it to a degree of curing that does not exceed 75% of the total degree of curing. Then, spray UV ink on its surface to form an ink pattern, and then cure it with UV light to obtain a GPU film 2 with a thickness of 1 mm.

[0043] Step 2: Place the polyurethane sole 1 onto the vacuum platform 3 with the bottom facing up, and then raise the vacuum platform 3.

[0044] Step 3: Start vacuuming, adsorb the preheated GPU film 2 onto the polyurethane sole 1, stabilize for 30 seconds, then stop vacuuming, and the vacuuming platform 3 descends to obtain the semi-finished polyurethane sole.

[0045] Step 4: Place the semi-finished polyurethane sole into the pressing mold, press it with the pressing machine for 5 seconds to obtain the pressed polyurethane sole.

[0046] Step 5: Place the pressed polyurethane sole in a constant temperature oven and cure it at 40°C for 5 hours to allow the GPU film 2 to cure a second time. After cooling at room temperature, trim and finish to obtain the coated polyurethane sole.

[0047] In step three, the GPU film 2 is preheated at 100°C; during vacuuming, the vacuum level is below 0.1 mbar.

[0048] The polyurethane composition consists of component A and component B in a volume ratio of 100:60.

[0049] Material A comprises the following raw materials in parts by weight: 100 parts of polyol prepolymer, 7 parts of chain extender, 0.5 parts of silica, 0.2 parts of catalyst, 0.3 parts of hydroxyethyl acrylate, and 0.005 parts of photoinitiator; the viscosity of the polyol prepolymer is 400 cp (at 75°C), and the moisture content is less than 1000 ppm; specifically, the polyol prepolymer is polybutylene adipate polyol.

[0050] Material B is an isocyanate prepolymer with an isocyanate content of 35%; specifically, the isocyanate prepolymer is a polyester polyol prepolymer modified with diphenylmethane diisocyanate (MDI).

[0051] The above-prepared coated polyurethane sole was subjected to abrasion resistance testing, and the obtained DIN abrasion resistance value was 42mm. 3 .

[0052] Example 2

[0053] A polyurethane shoe sole coating molding process includes the following steps:

[0054] Step 1: Prepare a polyurethane composition, cast it into a film, cure it at 70°C, and cure it to a degree of curing that does not exceed 75% of the total degree of curing. Then, spray UV ink on its surface to form an ink pattern, and then cure it with UV light to obtain a GPU film 2 with a thickness of 3 mm.

[0055] Step 2: Place the polyurethane sole 1 onto the vacuum platform 3 with the bottom facing up, and then raise the vacuum platform 3.

[0056] Step 3: Start vacuuming, adsorb the preheated GPU film 2 onto the polyurethane sole 1, stabilize for 8 seconds, then stop vacuuming, and the vacuuming platform 3 descends to obtain the semi-finished polyurethane sole.

[0057] Step 4: Place the semi-finished polyurethane sole into the pressing mold, press it with the pressing machine for 15 seconds to obtain the pressed polyurethane sole.

[0058] Step 5: Place the pressed polyurethane sole in a constant temperature oven and cure it at 70°C for 0.5 hours to allow the GPU film 2 to cure a second time. After cooling at room temperature, trim and finish the edges to obtain the coated polyurethane sole.

[0059] In step three, the GPU film 2 is preheated at 200°C; during vacuuming, the vacuum level is below 0.1 mbar.

[0060] The polyurethane composition consists of component A and component B in a volume ratio of 100:90.

[0061] Material A comprises the following raw materials in parts by weight: 100 parts of polyol prepolymer, 13 parts of chain extender, 3 parts of silica, 0.1 parts of catalyst, 1 part of hydroxyethyl acrylate, and 0.01 parts of photoinitiator; the viscosity of the polyol prepolymer is 1000 cp (at 75°C), and the moisture content is less than 1000 ppm; specifically, the polyol prepolymer is polytetrahydrofuran diol.

[0062] Material B is an isocyanate prepolymer with an isocyanate content of 14%; specifically, the isocyanate prepolymer is a diisocyanate-modified polyether polyol prepolymer.

[0063] The above-prepared coated polyurethane sole was subjected to abrasion resistance testing, and the obtained DIN abrasion resistance value was 39mm. 3 .

[0064] Example 3

[0065] A polyurethane shoe sole coating molding process includes the following steps:

[0066] Step 1: Prepare a polyurethane composition, cast it into a film, cure it at 55°C, and cure it to a degree of curing that does not exceed 75% of the total degree of curing. Then, spray UV ink on its surface to form an ink pattern, and then cure it with UV light to obtain a GPU film 2 with a thickness of 2 mm.

[0067] Step 2: Place the polyurethane sole 1 onto the vacuum platform 3 with the bottom facing up, and then raise the vacuum platform 3.

[0068] Step 3: Start vacuuming, adsorb the preheated GPU film 2 onto the polyurethane sole 1, stabilize for 18 seconds, then stop vacuuming, and the vacuuming platform 3 descends to obtain the semi-finished polyurethane sole.

[0069] Step 4: Place the semi-finished polyurethane sole 1 into the pressing mold, press it with the pressing machine for 9 seconds to obtain the pressed polyurethane sole.

[0070] Step 5: Place the pressed polyurethane sole in a constant temperature oven and cure it at 50°C for 2.2 hours to allow the GPU film 2 to cure a second time. After cooling at room temperature, trim and finish the edges to obtain the coated polyurethane sole.

[0071] In step three, the GPU film 2 is preheated at 150°C; during vacuuming, the vacuum level is below 0.1 mbar.

[0072] The polyurethane composition consists of component A and component B in a volume ratio of 100:75.

[0073] Material A comprises the following raw materials in parts by weight: 100 parts of polyol prepolymer, 9 parts of chain extender, 1.8 parts of silica, 0.15 parts of catalyst, 0.6 parts of hydroxyethyl acrylate, and 0.008 parts of photoinitiator; the viscosity of the polyol prepolymer is 700 cp (at 75°C), and the moisture content is less than 1000 ppm; specifically, the polyol prepolymer is composed of polyethylene adipate-propylene glycol ester and polypropylene glycol in a weight ratio of 1:1.

[0074] Material B is an isocyanate prepolymer with an isocyanate content of 20%; specifically, the isocyanate prepolymer is a polyester polyol prepolymer modified with diphenylmethane diisocyanate (MDI).

[0075] The above-prepared coated polyurethane sole was subjected to abrasion resistance testing, and the obtained DIN abrasion resistance value was 30mm. 3 .

[0076] Comparative Example 1

[0077] A polyurethane shoe sole coating molding process includes the following steps:

[0078] Step 1: Prepare a polyurethane composition, cast it into a film, and cure it completely at 55°C. Then, spray UV ink on its surface to form an ink pattern, and then cure it under UV light to obtain a GPU film 2 with a thickness of 2 mm.

[0079] Step 2: Place the polyurethane shoe 1 with the bottom facing up on the vacuum platform 3, and then raise the vacuum platform 3.

[0080] Step 3: Start vacuuming, adsorb the preheated GPU film 2 onto the polyurethane sole 1, stabilize for 18 seconds, then stop vacuuming, and the vacuuming platform 3 descends to obtain the semi-finished polyurethane sole.

[0081] Step 4: Place the semi-finished polyurethane sole into the pressing mold, press it with a pressing machine for 9 seconds, let it stand at room temperature for more than 6 days, trim and finish it to obtain the coated polyurethane sole.

[0082] In step three, the GPU film 2 is preheated at 150°C; during vacuuming, the vacuum level is below 0.1 mbar.

[0083] The polyurethane composition consists of component A and component B in a volume ratio of 100:75.

[0084] Material A comprises the following raw materials in parts by weight: 100 parts of polyol prepolymer, 9 parts of chain extender, 1.8 parts of silica, 0.15 parts of catalyst, 0.6 parts of hydroxyethyl acrylate, and 0.008 parts of photoinitiator; the viscosity of the polyol prepolymer is 700 cp (at 75°C), and the moisture content is less than 1000 ppm; specifically, the polyol prepolymer is composed of polyethylene adipate-propylene glycol ester and polypropylene glycol in a weight ratio of 1:1.

[0085] Material B is an isocyanate prepolymer with an isocyanate content of 23%; specifically, the isocyanate prepolymer is a polyester polyol prepolymer modified with diphenylmethane diisocyanate (MDI).

[0086] The above-prepared coated polyurethane sole was subjected to abrasion resistance testing. After cooling to room temperature, the DIN abrasion resistance value obtained by direct testing was 86 mm. 3 However, after the coated polyurethane sole was left at room temperature for 6 days, the DIN abrasion resistance value obtained was 32mm. 3 .

[0087] This application involves spraying a UV pattern onto an incompletely cured polyurethane film, followed by UV curing to form a GPU film 2. This GPU film 2 is then laminated with a polyurethane shoe sole 1 to give the polyurethane shoe sole different colors and textures, improving its aesthetics and protecting it from breakage, while also enhancing its wear resistance and slip resistance. Furthermore, the GPU film 2 is specifically molded using a two-stage curing process to ensure complete curing and coating of the polyurethane shoe sole 1, resulting in stable shoe sole performance. A comparison of test data from Example 3 and Comparative Example 1 shows that, to obtain a coated polyurethane shoe sole with similar performance, the coated polyurethane shoe sole prepared using the method specified in this application can be shipped after cooling at room temperature. Compared to the cooling time in Comparative Example 1, this application significantly shortens the cooling time, increases turnaround time, and thus improves production efficiency.

[0088] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made in accordance with the scope of the patent application and the contents of the specification of the present invention should still fall within the scope of the patent of the present invention.

Claims

1. A polyurethane shoe sole coating forming process, characterized by: The method comprises the following steps: Step one, preparing a polyurethane composition, casting into a film shape, curing and forming at 40-70℃, the curing degree being less than 75% of the overall complete curing degree, then spraying ink on the surface of the film to form an ink pattern, and then curing and forming by ultraviolet to obtain a GPU film with a thickness of 0.3-3mm; Step two, placing the polyurethane sole on a vacuum platform with the bottom surface facing upward, and then raising the vacuum platform; Step three, starting vacuum suction, and adsorbing the preheated GPU film onto the polyurethane sole, stopping vacuum suction after 8-30s of stabilization, and then lowering the vacuum platform to obtain a semi-finished polyurethane sole; Step four, placing the semi-finished polyurethane sole into a sole pressing mold, and pressing by a sole pressing machine for 5-15s to obtain a pressed polyurethane sole; Step five, placing the pressed polyurethane sole into a constant-temperature oven for secondary curing of the GPU film, cooling at room temperature, trimming and finishing to obtain a film-coated polyurethane sole.

2. A polyurethane shoe sole coating forming process according to claim 1, characterized in that: In step five, the secondary curing temperature is 40-70℃, and the curing time is 0.5-5h.

3. The polyurethane shoe sole coating forming process according to claim 1, characterized in that: In step three, the preheating temperature of the GPU film is 100-200℃.

4. The polyurethane shoe sole coating forming process according to claim 1, characterized in that: In step three, the vacuum degree is less than 0.1mbar during vacuum suction.

5. The polyurethane shoe sole coating forming process according to claim 1, characterized in that: The polyurethane composition is composed of A material and B material in a volume ratio of 100:60-90, the A material comprises the following raw materials in parts by weight: polyol prepolymer 100 parts, chain extender 7-13 parts, white carbon black 0.5-3 parts, catalyst 0.1-0.2 parts, hydroxyethyl acrylate 0.3-1 part, and photoinitiator 0.005-0.01 part.

6. A polyurethane sock forming process according to claim 5, wherein: The ink is UV ink.

7. A polyurethane shoe sole coating forming process according to claim 5, characterized in that: The viscosity of the polyol prepolymer is 400-1000cp, the hydroxyl group is 45-68mKOH / g, the acid value is less than 0.5mgKOH / g, and the moisture content is within 1000ppm.

8. A polyurethane sock forming process according to claim 7, wherein: The polyol prepolymer at least comprises one of polyester polyol and polyether polyol.

9. The polyurethane sock forming process of claim 5, wherein: The B material is an isocyanate prepolymer, and the isocyanate content is 14-35%.

10. The polyurethane sock forming process of claim 9, wherein: The isocyanate prepolymer at least comprises one of diisocyanate-modified polyester polyol prepolymer and diisocyanate-modified polyether polyol prepolymer.

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