A kind of polyurethane micro-foam material and preparation method thereof

Abstract

The present invention relates to the technical field of polyurethane material production, and discloses a polyurethane micro-foam material and a preparation method thereof, comprising a substrate layer, a polyurethane micro-foam layer, and a PU layer, wherein the substrate layer and the polyurethane micro-foam layer are bonded and connected by a polyurethane adhesive, and the PU layer is composed of a uniformly mixed polyurethane coating and coated on the polyurethane micro-foam layer. The polyurethane micro-foam material and the preparation method thereof, through the polyurethane micro-foam layer, a novel polyurethane micro-foam layer structure is designed, and a polyurethane micro-foam material is prepared, and the composite material not only inherits the characteristics of polyurethane shoe upper film with diverse textures, diverse colors, and easy processing, but also has the advantages of light weight, moisture permeability and breathability, folding resistance, waterproof, UV resistance, wear resistance, low temperature resistance, high temperature resistance, dirt resistance, soft and comfortable feel, etc., and is convenient to process through a dry coating-lamination process, simple to operate, and can be mass-produced.

Description

Technical Field

[0001] The invention relates to the technical field of polyurethane material production, in particular to a polyurethane micro-foam material and a preparation method thereof. Background Art

[0002] Polyurethane is mainly a linear structure with thermoplasticity. It has better stability, chemical resistance, resilience and mechanical properties than PVC foam materials. It has the advantages of thermoplasticity, high strength, high elongation, good resilience, wear resistance, oil resistance, aging resistance, low temperature resistance and other good properties. It is used in many fields such as textiles, electronics, packaging, medical, and automobiles. However, polyurethane has a dense structure, so the density of polyurethane film is generally large and the air permeability and moisture permeability are poor. When used as a shoe upper membrane in the field of shoe materials, it has disadvantages such as weak lightweight and poor air permeability, which can easily lead to poor comfort of shoes, making the wearer's feet feel stuffy and stuffy, easily causing sweating of the feet, and may increase the risk of bacterial growth on the feet, leading to foot skin problems such as athlete's foot. Summary of the invention

[0003] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0004] In view of the fact that the above or prior art has generally high density and poor air permeability and moisture permeability, when used as a shoe upper membrane in the field of shoe materials, it has the disadvantages of weak lightweight and poor air permeability.

[0005] In a first aspect, an embodiment of the present application provides a polyurethane micro-foam material, comprising a substrate layer (1), a polyurethane micro-foam layer (2), and a PU layer (3), characterized in that the substrate layer (1) and the polyurethane micro-foam layer (2) are bonded and connected by a polyurethane adhesive, and the PU layer (3) is composed of a uniformly mixed polyurethane coating and is coated on the polyurethane micro-foam layer.

[0006] In a second aspect, the present invention provides a method for preparing a polyurethane micro-foam material, comprising:

[0007] S1. Substrate production

[0008] The TPU masterbatch is prepared into a TPU single-layer film of a preset thickness, the hot-melt adhesive masterbatch is prepared into a hot-melt adhesive film, and the prepared TPU single-layer film is laminated on the hot-melt adhesive film to obtain a TPU hot-melt adhesive composite film;

[0009] S2. PU layer production

[0010] Coating a thermoplastic PU coating prepared by using a polyurethane resin, a hydrolysis resistance agent, a yellowing resistance agent and a color powder on a release surface of the polyester release film, and drying the coated polyester release film to obtain a PU layer;

[0011] S3. Production of polyurethane micro-foam layer

[0012] Selecting AB component raw materials for foaming, preparing a uniform foaming coating, and using a slit coating head of a bridge coating machine to uniformly coat the coating on the surface of the PU layer, and drying it in a bridge oven to obtain the polyurethane micro-foam layer, wherein during the drying process, an infrared drying instrument is used to detect the drying state of the polyurethane micro-foam layer, so that the thickness of the polyurethane micro-foam layer is within a preset thickness range;

[0013] S4. Semi-finished product preparation

[0014] A preset substrate is selected, and after laminating and bonding the TPU hot melt adhesive composite film, the PU layer and the polyurethane micro-foam layer by using a polyurethane adhesive, the polyurethane micro-foam layer and the substrate are compounded and dried, and the polyurethane micro-foam layer is rolled, aged, peeled, and cut to obtain an impact-resistant polyurethane composite leather material;

[0015] S5. Surface treatment

[0016] A scratch-resistant and anti-fouling surface treatment liquid is prepared by using a dirt-resistant surface treatment liquid, a curing agent, an anti-abrasive agent, a scratch-resistant additive and a functional color powder, and the scratch-resistant and anti-fouling surface treatment liquid is applied on the surface of the prepared impact-resistant polyurethane composite leather material and then dried;

[0017] S6. Finished product preparation

[0018] The impact-resistant polyurethane composite leather material that has been surface treated is aged and rolled up to obtain a polyurethane micro-foam material composite material.

[0019] As a further solution of the present invention: the substrate preparation includes:

[0020] S11, preparing a 0.1mm-5mm TPU single-layer film by cast extrusion of the TPU masterbatch, and preparing a 0.012mm-1mm hot melt adhesive film by cast extrusion of the hot melt adhesive masterbatch;

[0021] S12, laminating the TPU single-layer film on one end surface of the hot-melt adhesive film to obtain a TPU hot-melt adhesive composite film.

[0022] As a further solution of the present invention: the PU layer is made, comprising:

[0023] S21, uniformly mixing 70-100 parts of polyurethane resin, 0.03-1.5 parts of anti-hydrolysis agent, 0.1-1.5 parts of anti-yellowing agent and color powder to obtain a thermoplastic PU coating;

[0024] S22, using a slit coating head of a bridge coating machine to uniformly coat the thermoplastic PU coating on a release surface of a polyester release film, wherein the residual bonding force of the release surface of the polyester release film is 30-70%;

[0025] S23. Drying the polyester release film coated with the thermoplastic PU coating in a bridge oven to obtain the PU layer, wherein the PU layer has a thickness of 0.02-0.2 mm. When the bridge oven is in operation, the temperature in the baking chamber is set to rise from 40°C to 160°C, and then fall to 40°C after rising to 160°C.

[0026] As a further solution of the present invention: the preparation of the polyurethane micro-foam layer includes:

[0027] S31, selecting AB component raw materials for foaming, preparing a uniformly mixed foaming coating in a ratio of component A: component B = 1:1 to 2:1, and applying the foaming coating on the surface of the PU layer using a slit coating head of a bridge coating machine to obtain a polyurethane micro-foamed layer semi-finished product, wherein component A is a cyanate ester and component B is a polyol;

[0028] S32. Use a bridge oven to dry the semi-finished polyurethane micro-foam layer, and in the process of drying the semi-finished polyurethane micro-foam layer into the polyurethane micro-foam layer, use an infrared dryer to detect the drying state of the semi-finished polyurethane micro-foam layer, so that the thickness of the polyurethane micro-foam layer is within a preset thickness range, wherein when the bridge oven is working, the temperature in the baking chamber is set to rise from 40°C to 160°C, and after rising to 160°C, cool down to 40°C, and the preset thickness range is 0.02-2mm.

[0029] As a further solution of the present invention: during the operation of the bridge oven, the humidity of the environment outside the bridge oven is set to 40% to 70% by means of a humidifier and a dehumidifier.

[0030] As a further solution of the present invention: the substrate comprises at least one of the following: nylon cloth base, Oxford cloth base, glass fiber cloth base, cotton cloth base, Jiaji cloth base, microfiber cloth base, and the bonding production comprises:

[0031] S41, using a polyurethane adhesive, laminating and bonding the TPU hot melt adhesive composite film, the PU layer and the polyurethane micro-foam layer to obtain a multilayer film;

[0032] S42. The polyurethane micro-foam layer of the multilayer film is compounded with the substrate through a laminating wheel, and dried through a bridge-type oven to obtain a polyurethane foam composite leather semi-finished product, wherein when the bridge-type oven is in operation, the temperature in the drying chamber is set to rise from 40°C to 160°C, and after rising to 160°C, the temperature is lowered to 40°C.

[0033] As a further solution of the present invention: the semi-finished product production includes:

[0034] S51. Rolling up the polyurethane foam composite leather semi-finished product to obtain a polyurethane foam composite leather material, wherein the polyurethane foam composite leather material has a thickness of 0.2 mm to 0.7 mm.

[0035] S52, aging, peeling, and cutting the polyurethane foam composite leather material to obtain an impact-resistant polyurethane composite leather material, wherein the aging time is greater than 24 hours.

[0036] As a further solution of the present invention: the surface treatment comprises:

[0037] S61, 5-10 parts of anti-fouling surface treatment liquid, 1-3 parts of curing agent, 0.5-1 parts of wear-resistant additive, 0.5-1 parts of scratch-resistant additive and functional color are stirred and mixed to obtain 0.5-1 parts of scratch-resistant and anti-fouling surface treatment liquid, wherein the anti-fouling surface treatment liquid is prepared according to 10-20 parts of A and 5-10 parts of B, A is a polyurethane resin, B is an isocyanate cross-linking agent, and a fluorosilicone component is formed by mixing A and B, and the functional color powder includes one of the following: pearlescent color powder, fluorescent color powder, and gradient color powder;

[0038] S62, using a slit coating head of a bridge coating machine to evenly coat the scratch-resistant and antifouling surface treatment liquid on the surface of the prepared impact-resistant polyurethane composite leather material, wherein the mesh roller of the bridge coating machine has a mesh of 130;

[0039] S63. The impact-resistant polyurethane composite leather material coated with the scratch-resistant and anti-fouling surface treatment liquid is dried in a bridge oven, and the surface of the impact-resistant polyurethane composite leather material after drying is subjected to secondary surface treatment so that the surface thickness of the impact-resistant polyurethane composite leather material is 0.2 μm to 1 μm, wherein the temperature of the bridge oven is set to rise from 40°C to 160°C during drying, and after rising to 160°C, the temperature is lowered to 40°C.

[0040] As a further solution of the present invention: the total thickness of the polyurethane micro-foam material composite material is 0.2mm-1mm.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] 1. The present invention designs a novel polyurethane micro-foam layer structure through a polyurethane micro-foam layer, and prepares a polyurethane micro-foam material. The composite material not only inherits the characteristics of the polyurethane shoe upper film, such as diverse textures, diverse colors, and easy processing, but also has the advantages of light weight, moisture permeability and breathability, folding resistance, waterproofness, UV resistance, wear resistance, low temperature resistance, high temperature resistance, dirt resistance, soft and comfortable feel, etc. It is convenient to process through a dry coating-lamination process, simple to operate, and can be mass-produced. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a schematic diagram of the structure of a polyurethane micro-foam material;

[0044] Figure 2 A flow chart for preparing a polyurethane micro-foam material;

[0045] Figure 3 This is a schematic diagram of a test report for a polyurethane micro-foam material;

[0046] Figure 4 This is a schematic diagram of a test report on the waterproof, moisture permeability and breathability of a polyurethane micro-foam material.

[0047] In the figure: 1. substrate layer; 2. polyurethane micro-foam layer; 3. PU layer. DETAILED DESCRIPTION

[0048] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, the specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings.

[0049] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0050] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments. Embodiment 1

[0051] See also Figure 1-4, which is the first embodiment of the present invention, and provides a polyurethane micro-foam material and a preparation method thereof, comprising a substrate layer 1, a polyurethane micro-foam layer 2, and a PU layer 3, wherein the substrate layer 1 and the polyurethane micro-foam layer 2 are bonded and connected by a polyurethane adhesive, and the PU layer 3 is composed of a uniformly mixed polyurethane coating and is coated on the polyurethane micro-foam layer;

[0052] The preparation method thereof comprises

[0053] Step 1: Substrate preparation: a 0.1 mm to 5 mm TPU single-layer film is prepared by cast extrusion of a TPU masterbatch, a 0.012 mm to 1 mm hot melt adhesive film is prepared by cast extrusion of a hot melt adhesive masterbatch, and the TPU single-layer film is laminated on one end surface of the hot melt adhesive film to obtain a TPU hot melt adhesive composite film;

[0054] Step 2: PU layer preparation, 70-100 parts of polyurethane resin, 0.03-1.5 parts of hydrolysis resistance agent, 0.1-1.5 parts of yellowing resistance agent and color powder are uniformly mixed to obtain thermoplastic PU coating, and the slit coating head of the bridge coating machine is used to uniformly coat the thermoplastic PU coating on the release surface of the polyester release film, wherein the residual bonding force of the release surface of the polyester release film is 30-70%, and the polyester release film coated with the thermoplastic PU coating is dried by a bridge oven to obtain the PU layer, wherein the thickness of the PU layer is 0.02-0.2mm, and when the bridge oven is working, the temperature in the drying chamber is set to rise from 40°C to 160°C, and after rising to 160°C, it is cooled to 40°C;

[0055] Step 3: Production of polyurethane micro-foam layer, select AB component raw materials for foaming, component A (cyanate ester): component B (polyol) = 1:1 to 2:1, prepare uniform foaming coating, and use the slit coating head of the bridge coating machine to evenly coat the fully mixed foaming layer coating on the surface of the PU layer produced in step S2, use a bridge oven and use the temperature increasing and decreasing method to bake the coated product at 40℃-160℃, and use an infrared dryer to measure whether the product is in a foamed to semi-dry or completely dry state, and the thickness of this foaming layer is 0.02-2mm;

[0056] Step 4: laminating and making, using a polyurethane adhesive, laminating and bonding the TPU hot melt adhesive composite film, the PU layer and the polyurethane micro-foam layer to obtain a multi-layer film, laminating the polyurethane micro-foam layer of the multi-layer film with the substrate through a laminating wheel, and drying through a bridge oven to obtain a polyurethane foam composite leather semi-finished product, wherein the temperature in the drying chamber of the bridge oven is set to rise from 40°C to 160°C when the temperature rises to 160°C, and then drops to 40°C after the temperature rises to 160°C;

[0057] Step 5: Surface treatment, 5-10 parts of anti-fouling surface treatment liquid, 1-3 parts of curing agent, 0.5-1 parts of wear-resistant additives, 0.5-1 parts of scratch-resistant additives and functional color parts are stirred and mixed to obtain 0.5-1 parts of scratch-resistant and anti-fouling surface treatment liquid, wherein the anti-fouling surface treatment liquid is prepared according to 10-20 parts of A and 5-10 parts of B, A is a polyurethane resin, B is an isocyanate cross-linking agent, and a fluorosilicone component is formed by mixing A and B. The functional color powder includes one of the following: pearlescent color powder, fluorescent color powder, and gradient color powder. The slit coating head of a bridge coating machine is used to uniformly coat the surface of the prepared impact-resistant polyurethane composite leather material with the scratch-resistant and anti-fouling surface treatment liquid, wherein the mesh roller of the bridge coating machine is 130 mesh, and the mesh of 130 mesh is 100 mesh. The roller forms a layer of fine texture on the coating material to increase the touch and anti-slip properties, while the slit coating head controls the thickness and uniformity of the coating material. Under the action of the mesh roller, it ensures that the coated liquid can be evenly distributed on the surface of the substrate, and the thickness of the coating material is properly controlled to a certain extent. The impact-resistant polyurethane composite leather material coated with the scratch-resistant and anti-fouling surface treatment liquid is dried through a bridge oven, and the surface of the impact-resistant polyurethane composite leather material after drying is subjected to secondary surface treatment so that the surface thickness of the impact-resistant polyurethane composite leather material is 0.2μm to 1μm, wherein the temperature of the bridge oven is set to rise from 40°C to 160°C during drying, and after rising to 160°C, the temperature is lowered to 40°C;

[0058] Step 6: Finished product production step, the surface treated product is matured and rolled up to obtain a polyurethane micro-foam material composite material, the total thickness of the polyurethane micro-foam material composite material is 0.2mm-1mm. Embodiment 2

[0059] Step 1: Preparation of substrate: Mix TPU masterbatch and UV anti-ultraviolet agent according to the ratio, extrude it into 0.2mm thick TPU multilayer film through a twin-screw extruder, use electrostatic powder spraying technology to evenly apply fine-grained hot melt adhesive powder on the surface of the TPU film, and use hot pressing laminating equipment to laminate and shape the TPU film coated with powdered hot melt adhesive to form a composite film.

[0060] Step 2: Preparation of PU layer: 70 parts of polyurethane resin, 1 part of hydrolysis resistance agent, 1 part of yellowing resistance agent, color powder and 10 parts of calcium carbonate filler are mixed, and the prepared PU coating is transferred to a special release paper with a release effect by a transfer coating process, and then sent into a UV curing machine, and quickly cured by UV light to obtain the PU film layer with a thickness of 0.05 mm.

[0061] Step 3: Preparation of polyurethane micro-foam layer: select environmentally friendly water-based foaming agent and mix it with component A and component B in a ratio of 2:1. After stirring evenly, use low-pressure injection equipment to complete foaming coating. The foaming layer is formed by free foaming or auxiliary mold support to obtain a 0.1-1.5mm thick micro-foam layer.

[0062] Step 4: Surface treatment. The prepared polyurethane micro-foamed composite material is sent to the surface coating equipment. According to the required performance requirements, the anti-fouling surface treatment liquid (mixed with the curing agent in a 1:1 ratio), the curing agent (mixed with the anti-fouling surface treatment liquid in a 1:1 ratio), the wear-resistant additive (added at a ratio of 5%-10% of the total coating material) and the scratch-resistant additive (5%-10%) are selected and proportioned. Through the coating process, the mixed surface treatment liquid is evenly coated on the surface of the composite material, and the thickness and uniformity of the coating layer are ensured. Subsequently, the coating layer is cured through the drying equipment, and finally a surface-treated composite material with pollution resistance, wear resistance and scratch resistance is obtained.

[0063] Step 5: Lamination and finished product production: Use polyurethane adhesive to laminate and bond the TPU hot melt adhesive composite film, PU layer and polyurethane micro-foam layer, laminate the obtained multi-layer film to the prefabricated substrate, and dry it in a hot air oven. Roll it up to obtain the final polyurethane micro-foam composite material, and then go through a natural curing process for more than 24 hours. Embodiment 3

[0064] Step 1: Preparation of substrate: Mix TPU masterbatch and UV anti-ultraviolet agent according to the ratio, extrude it into 0.2mm thick TPU multilayer film through a twin-screw extruder, use electrostatic powder spraying technology to evenly apply fine-grained hot melt adhesive powder on the surface of the TPU film, and use hot pressing laminating equipment to laminate and shape the TPU film coated with powdered hot melt adhesive to form a composite film.

[0065] Step 2: Preparation of PU layer: 70 parts of polyurethane resin, 1 part of hydrolysis resistance agent, 1 part of yellowing resistance agent, color powder and 10 parts of calcium carbonate filler are mixed, and the prepared PU coating is transferred to a special release paper with a release effect by a transfer coating process, and then sent into a UV curing machine, and quickly cured by UV light to obtain the PU film layer with a thickness of 0.05 mm.

[0066] Step 3: Preparation of polyurethane micro-foam layer. Select environmentally friendly water-based foaming agent and mix it with component A and component B in a ratio of 1.5:1, that is, use 1.5 parts of component A for every 1 part of component B. Mix and stir evenly, use low-pressure injection equipment for foaming and coating, and also complete the molding of the foaming layer through free foaming or auxiliary mold support. The thickness of the finished micro-foam layer is 0.1-1.5mm.

[0067] Step 4: Perform surface treatment, feed the prepared polyurethane micro-foam composite material into the surface coating equipment, and then mix the anti-fouling surface treatment liquid, curing agent, wear-resistant additive and scratch-resistant additive evenly according to the ratio requirements. The ratio is: anti-fouling surface treatment liquid: curing agent: wear-resistant additive: scratch-resistant additive = 1:1:5%-10%:5%-10%. Through the coating process, the mixed surface treatment liquid is evenly coated on the surface of the composite material to ensure uniform coating, avoid bubbles and uneven thickness, adjust the coating speed, pressure, temperature and other process parameters, use drying equipment to fully cure the coating layer, ensure that the surface treatment's pollution resistance, wear resistance and scratch resistance are improved, and finally obtain a polyurethane micro-foam composite material with surface treatment.

[0068] Step 5: Lamination and finished product production: Use polyurethane adhesive to laminate and bond the TPU hot melt adhesive composite film, PU layer and polyurethane micro-foam layer, laminate the obtained multi-layer film to the prefabricated substrate, and dry it in a hot air oven. Roll it up to obtain the final polyurethane micro-foam composite material, and then go through a natural curing process for more than 24 hours. Embodiment 4

[0069] Step 1: Preparation of substrate: Mix TPU masterbatch and UV anti-ultraviolet agent according to the ratio, extrude it into 0.2mm thick TPU multilayer film through a twin-screw extruder, use electrostatic powder spraying technology to evenly apply fine-grained hot melt adhesive powder on the surface of the TPU film, and use hot pressing laminating equipment to laminate and shape the TPU film coated with powdered hot melt adhesive to form a composite film.

[0070] Step 2: Preparation of PU layer: 70 parts of polyurethane resin, 1 part of hydrolysis resistance agent, 1 part of yellowing resistance agent, color powder and 10 parts of calcium carbonate filler are mixed, and the prepared PU coating is transferred to a special release paper with a release effect by a transfer coating process, and then sent into a UV curing machine, and quickly cured by UV light to obtain the PU film layer with a thickness of 0.05 mm.

[0071] Step 3: Preparation of polyurethane micro-foam layer. Select an environmentally friendly water-based foaming agent and mix it with component A and component B in a 1:1 ratio, that is, component A and component B are mixed in equal amounts. After the mixture is stirred evenly, a low-pressure injection device is used for foaming and coating operations. Then, the foaming layer is formed by free foaming or using a mold support. The thickness of the obtained micro-foam layer is between 0.1-1.5mm.

[0072] Step 4: Perform surface treatment, feed the prepared polyurethane micro-foam composite material into the surface coating equipment, and then mix the anti-fouling surface treatment liquid, curing agent, wear-resistant additive and scratch-resistant additive evenly according to the ratio requirements. The ratio is: anti-fouling surface treatment liquid: curing agent: wear-resistant additive: scratch-resistant additive = 1:1:5%-10%:5%-10%. Through the coating process, the mixed surface treatment liquid is evenly coated on the surface of the composite material to ensure uniform coating, avoid bubbles and uneven thickness, adjust the coating speed, pressure, temperature and other process parameters, use drying equipment to fully cure the coating layer, ensure that the surface treatment's pollution resistance, wear resistance and scratch resistance are improved, and finally obtain a polyurethane micro-foam composite material with surface treatment.

[0073] Step 5: Lamination and finished product production. Use polyurethane adhesive to laminate and bond the TPU hot melt adhesive composite film, PU layer and polyurethane micro-foam layer of the surface-treated polyurethane micro-foam composite material. Lay the obtained multi-layer film to the prefabricated substrate and dry it in a hot air oven. Finally, roll up the final polyurethane micro-foam composite material and undergo a natural aging process of more than 24 hours to ensure that the product quality is stable and meets the expected performance requirements. Embodiment 5

[0074] Step 1: Preparation of substrate: Using co-extrusion technology, TPU masterbatches with different functions are co-extruded to form a multi-layer structure. The thickness of each film layer is controlled at about 0.25 mm. The hot melt adhesive dissolved in an environmentally friendly solvent (acetone) is rolled and laminated with the TPU multi-layer film.

[0075] Step 2: Preparation of PU layer: Mix 80 parts of special toughened polyurethane (TPU-based polyurethane), 0.5 parts of hydrolysis resistance agent, 0.5 parts of yellowing resistance agent and color powder until uniform, use a rubber scraper coating head to coat the mixture on high-strength release paper, and dry it through an infrared heating system to obtain a PU layer.

[0076] Step 3: Preparation of polyurethane micro-foam layer: Microspheres foaming powder is mixed with polyurethane prepolymer, and sprayed on the surface of PU film using electrostatic spraying equipment to form a foaming layer, which is then heated under high pressure and then cooled naturally to achieve a micro-foam structure.

[0077] Step 4: Surface treatment. The prepared polyurethane micro-foamed composite material is sent to the surface coating equipment. The ratio of the anti-fouling surface treatment liquid to the curing agent is 1:1. The anti-fouling surface treatment liquid, curing agent, wear-resistant additive and scratch-resistant additive are mixed evenly according to the proportion requirements. The ratio is: anti-fouling surface treatment liquid: curing agent: wear-resistant additive: scratch-resistant additive = 1:1:5%-10%:5%-10%. Through the coating process, the mixed surface treatment liquid is evenly coated on the surface of the composite material to ensure uniform coating, avoid bubbles and uneven thickness, ensure that the coating layer thickness and uniformity meet the requirements, adjust the coating speed, pressure and temperature and other process parameters, use drying equipment to fully cure the coating layer, ensure that the surface treatment's pollution resistance, wear resistance and scratch resistance are improved, and finally obtain a polyurethane micro-foamed composite material after surface treatment to ensure stable product quality and meet the expected performance requirements.

[0078] Step 5: Lamination and finished product production. Use solvent-free polyurethane glue to stack and bond the layers of materials, adhere them to the base material under pressure and cure them through heat treatment. After cutting and winding, the finished product is obtained, and it is aged for at least 24 hours to ensure stable performance.

[0079] In summary, a new type of polyurethane micro-foam layer structure was designed through the polyurethane micro-foam layer, and a polyurethane micro-foam material was prepared. This composite material not only inherited the characteristics of the polyurethane shoe upper film such as diverse textures, diverse colors, and easy processing, but the product also has the advantages of light weight, moisture permeability and breathability, folding resistance, waterproofness, UV resistance, wear resistance, low temperature resistance, high temperature resistance, dirt resistance, soft and comfortable feel, etc. It is easy to process through the dry coating-lamination process, simple to operate, and can be mass-produced.

[0080] Importantly, it should be noted that the construction and arrangement of the present application shown in a number of different exemplary embodiments are only exemplary. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible (e.g., the size, scale, structure, shape and proportion of various elements, and parameter values ​​(e.g., temperature, pressure, etc.), mounting arrangements, use of materials, color, changes in orientation, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in the application. For example, an element shown as integrally formed may be composed of multiple parts or elements, the position of the element may be inverted or otherwise changed, and the nature or number or position of the discrete element may be altered or changed. Therefore, all such modifications are intended to be included within the scope of the present invention. The order or sequence of any process or method steps may be changed or reordered according to an alternative embodiment. In the claims, any "device plus function" clause is intended to cover the structure described herein that performs the function, and is not only structurally equivalent but also equivalent structure. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments without departing from the scope of the present invention. Therefore, the invention is not limited to a specific embodiment, but extends to numerous modifications still falling within the scope of the appended claims.

[0081] Additionally, in order to provide a concise description of exemplary embodiments, all features of an actual embodiment may not be described (ie, those features that are not relevant to the best mode presently contemplated for carrying out the invention or those features that are not relevant to implementing the invention).

[0082] It will be appreciated that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but will be a routine task of design, fabrication, and production for those of ordinary skill having the benefit of this disclosure without undue experimentation.

[0083] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a polyurethane micro-foam material, comprising a substrate layer (1), a polyurethane micro-foam layer (2), and a PU layer (3), characterized in that: The substrate layer (1) and the polyurethane micro-foam layer (2) are bonded and connected by a polyurethane adhesive, and the PU layer (3) is composed of a uniformly mixed polyurethane coating and is coated on the polyurethane micro-foam layer. The preparation method comprises: S1. Substrate production The TPU masterbatch is prepared into a TPU single-layer film of a preset thickness, the hot-melt adhesive masterbatch is prepared into a hot-melt adhesive film, and the prepared TPU single-layer film is laminated on the hot-melt adhesive film to obtain a TPU hot-melt adhesive composite film; S2. PU layer production Coating a thermoplastic PU coating prepared by using a polyurethane resin, a hydrolysis resistance agent, a yellowing resistance agent and a color powder on a release surface of the polyester release film, and drying the coated polyester release film to obtain a PU layer; S3. Production of polyurethane micro-foam layer Selecting AB component raw materials for foaming, preparing a uniform foaming coating, and using a slit coating head of a bridge coating machine to uniformly coat the coating on the surface of the PU layer, and drying it in a bridge oven to obtain the polyurethane micro-foam layer, wherein during the drying process, an infrared drying instrument is used to detect the drying state of the polyurethane micro-foam layer, so that the thickness of the polyurethane micro-foam layer is within a preset thickness range; S4. Semi-finished product preparation A preset substrate is selected, and after laminating and bonding the TPU hot melt adhesive composite film, the PU layer and the polyurethane micro-foam layer by using a polyurethane adhesive, the polyurethane micro-foam layer and the substrate are compounded and dried, and the polyurethane micro-foam layer is rolled, aged, peeled, and cut to obtain an impact-resistant polyurethane composite leather material; S5. Surface treatment A scratch-resistant and anti-fouling surface treatment liquid is prepared by using a dirt-resistant surface treatment liquid, a curing agent, an anti-abrasive agent, a scratch-resistant additive and a functional color powder, and the scratch-resistant and anti-fouling surface treatment liquid is applied on the surface of the prepared impact-resistant polyurethane composite leather material and then dried; S6. Finished product preparation Curing and rolling the impact-resistant polyurethane composite leather material after surface treatment to obtain a polyurethane micro-foam material composite material; The substrate production also includes: S11, preparing a 0.1mm-5mm TPU single-layer film by cast extrusion of the TPU masterbatch, and preparing a 0.012mm-1mm hot melt adhesive film by cast extrusion of the hot melt adhesive masterbatch; S12, laminating the TPU single-layer film on one end surface of the hot-melt adhesive film to obtain a TPU hot-melt adhesive composite film.

2. The method for preparing a polyurethane micro-foam material according to claim 1, characterized in that: The PU layer is made, comprising: S21, uniformly mixing 70-100 parts of polyurethane resin, 0.03-1.5 parts of anti-hydrolysis agent, 0.1-1.5 parts of anti-yellowing agent and color powder to obtain a thermoplastic PU coating; S22, using a slit coating head of a bridge coating machine to uniformly coat the thermoplastic PU coating on a release surface of a polyester release film, wherein the residual bonding force of the release surface of the polyester release film is 30-70%; S23. Drying the polyester release film coated with the thermoplastic PU coating in a bridge oven to obtain the PU layer, wherein the PU layer has a thickness of 0.02-0.2 mm. When the bridge oven is working, the temperature in the baking chamber is set to rise from 40°C to 160°C, and then cool down to 40°C after rising to 160°C.

3. The method for preparing a polyurethane micro-foam material according to claim 1, characterized in that: The polyurethane micro-foam layer is made by: S31, selecting AB component raw materials for foaming, preparing a uniformly mixed foaming coating in a ratio of component A: component B = 1:1 to 2:1, and applying the foaming coating on the surface of the PU layer using a slit coating head of a bridge coating machine to obtain a polyurethane micro-foamed layer semi-finished product, wherein component A is a cyanate ester and component B is a polyol; S32. Use a bridge oven to dry the semi-finished polyurethane micro-foam layer, and in the process of drying the semi-finished polyurethane micro-foam layer into the polyurethane micro-foam layer, use an infrared dryer to detect the drying state of the semi-finished polyurethane micro-foam layer, so that the thickness of the polyurethane micro-foam layer is within a preset thickness range, wherein when the bridge oven is working, the temperature in the baking chamber is set to rise from 40°C to 160°C, and after rising to 160°C, cool down to 40°C, and the preset thickness range is 0.02-2mm.

4. The method for preparing a polyurethane micro-foam material according to claim 3, characterized in that: During the operation of the bridge oven, the humidity of the environment outside the bridge oven is set to 40% to 70% through a humidifier and a dehumidifier.

5. The method for preparing a polyurethane micro-foam material according to claim 1, characterized in that: The substrate comprises at least one of the following: nylon cloth base, Oxford cloth base, glass fiber cloth base, cotton cloth base, Jiaji cloth base, microfiber cloth base, and the preparation method thereof further comprises: S41, using a polyurethane adhesive, laminating and bonding the TPU hot melt adhesive composite film, the PU layer and the polyurethane micro-foam layer to obtain a multilayer film; S42. The polyurethane micro-foam layer of the multilayer film is compounded with the substrate through a laminating wheel, and dried through a bridge oven to obtain a polyurethane foam composite leather semi-finished product, wherein when the bridge oven is working, the temperature in the baking chamber is set to rise from 40°C to 160°C, and after rising to 160°C, the temperature is lowered to 40°C.

6. The method for preparing a polyurethane micro-foam material according to claim 5, characterized in that: The semi-finished product production includes: S51, rolling up the polyurethane foam composite leather semi-finished product to obtain a polyurethane foam composite leather material, wherein the polyurethane foam composite leather material has a thickness of 0.2 mm-0.7 mm; S52, aging, peeling, and cutting the polyurethane foam composite leather material to obtain an impact-resistant polyurethane composite leather material, wherein the aging time is greater than 24 hours.

7. The method for preparing a polyurethane micro-foam material according to claim 1, characterized in that: The surface treatment includes: S61, 5-10 parts of anti-fouling surface treatment liquid, 1-3 parts of curing agent, 0.5-1 parts of wear-resistant additive, 0.5-1 parts of scratch-resistant additive and functional color are stirred and mixed to obtain 0.5-1 parts of scratch-resistant and anti-fouling surface treatment liquid, wherein the anti-fouling surface treatment liquid is prepared according to 10-20 parts of A and 5-10 parts of B, A is a polyurethane resin, B is an isocyanate cross-linking agent, and a fluorosilicone component is formed by mixing A and B, and the functional color powder includes one of the following: pearlescent color powder, fluorescent color powder, and gradient color powder; S62, using a slit coating head of a bridge coating machine to evenly coat the scratch-resistant and antifouling surface treatment liquid on the surface of the prepared impact-resistant polyurethane composite leather material, wherein the mesh roller of the bridge coating machine has a mesh of 130; S63. The impact-resistant polyurethane composite leather material coated with the scratch-resistant and anti-fouling surface treatment liquid is dried in a bridge oven, and the surface of the impact-resistant polyurethane composite leather material after drying is subjected to secondary surface treatment so that the surface thickness of the impact-resistant polyurethane composite leather material is 0.2 μm to 1 μm, wherein the temperature of the bridge oven is set to rise from 40°C to 160°C during drying, and after rising to 160°C, the temperature is lowered to 40°C.

8. The method for preparing a polyurethane micro-foam material according to claim 1, characterized in that: The total thickness of the polyurethane micro-foam material composite material is 0.2mm-1mm.

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