Humidity-heat-resistant polyurethane microporous foaming foam as well as preparation method and application thereof

Abstract

In order to solve the problems that existing polyurethane foam is poor in rebound resilience and poor in dimensional stability in a high-humidity and high-heat environment, the invention provides damp-heat-resistant polyurethane microporous foaming foam and a preparation method and application thereof.The damp-heat-resistant polyurethane microporous foaming foam comprises a polyurethane microporous foaming layer, a UV photocuring damp-heat-resistant layer and a base layer, the polyurethane microcellular foaming layer is arranged on the surface of at least one side of the base layer, and the UV photocuring damp-heat-resistant layer is arranged on the surface of the side, away from the base layer, of the polyurethane microcellular foaming layer. According to the damp-heat-resistant polyurethane micropore foaming foam, the UV light curing damp-heat-resistant layer has good damp resistance and high heat resistance, water vapor is effectively prevented from entering the polyurethane micropore foaming layer, the damp-heat-resistant performance of the foam is effectively improved, and the foam has the excellent effects of being low in water absorption rate, good in hydrophobic performance and high in rebound rate.

Description

Technical Field

[0001] The invention relates to the technical field of polyurethane foam, and in particular to a moisture-heat resistant polyurethane microporous foam and a preparation method and application thereof. Background Art

[0002] Polyurethane foam is a porous polymer material produced by the reaction of polyisocyanate and polyol, which contains a large number of carbamate groups (-NHCOO-) on the main chain of the molecule. Polyurethane foam has become the first choice of cushioning material due to its excellent resilience, unique pore structure and porosity. The compression permanent deformation of polyurethane foam has also become an important indicator to measure the performance of foam.

[0003] However, during the use of existing polyurethane foam, such as in a high humidity and high heat environment, the high temperature destroys the flexibility of the molecular chain and the cross-linking structure of the polyurethane foam, the structure is destroyed, the pore structure collapses, and the rebound performance is poor; under high humidity conditions, the polyurethane foam will absorb a large amount of water and there will be a problem of pore stress imbalance, and the moisture absorption expansion and drying shrinkage will cause the size of the polyurethane foam to change, the dimensional stability of the polyurethane foam will deteriorate, and the polyurethane foam will shrink and deform, which will subsequently lead to serious problems such as separation, degumming, cracking, and wrinkling between the composite layer materials. Summary of the invention

[0004] In view of the problems that existing polyurethane foam has poor rebound performance and poor dimensional stability in high humidity and high heat environment, the present application provides a moisture and heat resistant polyurethane microporous foam and a preparation method and application thereof.

[0005] On the one hand, the present invention provides a moisture- and heat-resistant polyurethane microporous foam cotton, comprising a polyurethane microporous foam layer, a UV light-cured moisture- and heat-resistant layer and a base layer, wherein the polyurethane microporous foam layer is arranged on at least one side surface of the base layer, and the UV light-cured moisture- and heat-resistant layer is arranged on the side surface of the polyurethane microporous foam layer away from the base layer.

[0006] Preferably, the raw materials of the polyurethane microporous foam layer include component A and component B, wherein the component A includes a polyether polyol mixture and a modified foaming agent, wherein the modified foaming agent includes a polyether-modified polysiloxane compound; and the component B includes an isocyanate compound; The raw material of the UV light-curable moisture-resistant layer includes polyurethane acrylate.

[0007] Preferably, the polyether polyol mixture includes a first polyether polyol, and a second polyether polyol modified with styrene and acrylonitrile. The hydroxyl value of the first polyether polyol is 30-100 mgKOH / g, and the hydroxyl value of the second polyether polyol is 20-100 mgKOH / g; the mass ratio of the first polyether polyol to the second polyether polyol is (7.5-8.5):(1.5-2.5).

[0008] Preferably, the raw materials of the polyurethane microcellular foaming layer include the following components: based on 100 parts of the polyether polyol mixture, the first catalyst is 0.6-1.0 part, the foaming agent is 3.5-4.0 parts, the chain extender is 0.1-2.0 parts, the modified foam stabilizer is 0.8-1.5 parts, the isocyanate compound is 6-15 parts, and the initiator is 0.4-0.8 part; The foaming agent includes water, and the chain extender includes one or more of aziridine, polycarbodiimide, and diethanolamine; The first catalyst includes an organometallic catalyst, and the organometallic catalyst includes one of bismuth neodecanoate, bismuth isooctanoate, zinc neodecanoate, and zinc isooctanoate; The isocyanate compound includes one or both of isophorone diisocyanate and diphenylmethane diisocyanate; The initiator includes persulfate.

[0009] Preferably, the raw materials of the UV-curable moisture and heat resistant layer include the following components: 20-50 parts of acrylate compounds, 40-70 parts of diluents, 3-7 parts of photoinitiators, and 0.1-3 parts of second additives; The acrylate compounds include the polyurethane acrylate and the epoxy-modified acrylate resin; in the acrylate compounds, the parts ratio of the polyurethane acrylate to the epoxy-modified acrylate resin is (15-40):(5-10); The second additives include one or both of a leveling agent and a polymerization inhibitor; The diluents include one or both of dipropylene glycol diacrylate resin and trimethylolpropane triacrylate; The photoinitiators include one or both of 1-hydroxycyclohexyl phenyl ketone and 2,4,6-trimethylbenzoyl diphenylphosphine oxide.

[0010] Preferably, the material of the base layer is one of a polymer material, a metal material, and an alloy material; The thickness of the polyurethane microcellular foaming layer is 0.1 mm-1 mm; the thickness of the UV-curable moisture and heat resistant layer is 10 μm-100 μm; Or, the adhesion between the polyurethane microcellular foaming layer and the UV-curable moisture and heat resistant layer is grade 0.

[0011] In a second aspect, the present application provides a method for preparing the above-mentioned polyurethane microporous foamed sponge resistant to heat and humidity, which is characterized by comprising the following steps: Mix the raw materials of the polyurethane microporous foamed layer evenly and then coat them on at least one surface of the base layer, heat and cure to obtain the polyurethane microporous foamed layer on at least one surface of the base layer; Mix the raw materials of the UV-curable heat and humidity resistant layer evenly and then coat them on the surface of the polyurethane microporous foamed layer facing away from the base layer, and carry out photocuring under UV light irradiation conditions to form the UV-curable heat and humidity resistant layer on the surface of the polyurethane microporous foamed layer facing away from the base layer, thereby obtaining the polyurethane microporous foamed sponge resistant to heat and humidity.

[0012] Preferably, the temperature for heat curing is 115-120 °C, and the time for heat curing is 15-20 min; in the step of curing under UV light irradiation conditions, the curing time is 1-3 s.

[0013] Preferably, the raw materials of the polyurethane microporous foamed layer include a modified foam stabilizer, and the modified foam stabilizer includes a polyether-modified polysiloxane compound. The preparation of the modified foam stabilizer including the polyether-modified polysiloxane compound includes the following steps; Prepare a polysiloxane compound of low hydrogen-containing silicone oil: Add high hydrogen-containing silicone oil, cyclic siloxane compound, linear siloxane compound and a second catalyst into a reaction vessel, react at 60-65 °C for 3-5 h, and carry out a first post-treatment after the reaction ends to obtain the polysiloxane compound of low hydrogen-containing silicone oil; the mass fraction of active hydrogen in the polysiloxane compound of low hydrogen-containing silicone oil is 0.08%-1%; Prepare a polyether-modified polysiloxane compound: dehydrate the polysiloxane compound of low hydrogen-containing silicone oil, non-ionic surfactant and organic solvent, and then add a third catalyst to carry out a heating reaction under a protective atmosphere. The heating reaction temperature is 100-120 °C, and the heating reaction time is 3-5 h. After the heating reaction ends, carry out a second post-treatment to obtain the polyether-modified polysiloxane compound; the non-ionic surfactant includes allyl-terminated polyoxyalkylene ether; The second catalyst includes an inorganic acid catalyst; The third catalyst is a first mixed solution composed of chloroplatinic acid and isopropanol, and the mass fraction of chloroplatinic acid in the first mixed solution is 4-7%; The cyclic siloxane compound includes dimethylcyclosiloxane; The linear siloxane compound includes hexamethyldisilane.

[0014] In a third aspect, the present application provides an application of the above-mentioned polyurethane microcellular foamed cotton resistant to heat and humidity or the polyurethane microcellular foamed cotton resistant to heat and humidity prepared by the above-mentioned preparation method in the fields of buffer materials, heat insulation materials and electronic products.

[0015] The polyurethane microcellular foamed cotton resistant to heat and humidity provided by the present application has the following functions: 1) The UV-curable heat and humidity resistant layer is disposed on the surface of the polyurethane microcellular foamed layer facing away from the base layer. The carbonyl oxygen (O=C) and ether oxygen (-O-) contained in the polyurethane microcellular foamed layer can form hydrogen bonds with the UV-curable heat and humidity resistant layer. The polyurethane microcellular foamed layer contains urethane groups (-NHCOO-), and the amino groups in the urethane groups can form chemical bonds with the UV-curable heat and humidity resistant layer, so that the UV-curable heat and humidity resistant layer and the polyurethane microcellular foamed layer form strong adhesion. 2) The UV-curable heat and humidity resistant layer has good moisture resistance and high heat resistance. It is disposed on the surface of the polyurethane microcellular foamed layer, effectively preventing water vapor from entering the polyurethane microcellular foamed layer during use, effectively improving the heat and humidity resistance of the foamed cotton, and extending the service life of the polyurethane microcellular foamed cotton; at the same time, it also enables the polyurethane microcellular foamed cotton to have excellent low water absorption and good hydrophobic properties. 3) The three-layer structure of the polyurethane microcellular foamed cotton makes the foamed cotton not easy to adhere when it is formed and rolled out; under the conditions of high temperature and high humidity, the foamed cotton structure can maintain excellent dimensional stability, without shrinkage and deformation, avoiding serious problems such as separation, degumming, cracking and wrinkling between the composite layer materials. 4) The pores in the polyurethane microcellular foamed layer are evenly distributed, making the foamed cotton have excellent resilience performance and high resilience rate, effectively avoiding the problem of deformation caused by extrusion during long-term use, and ensuring the normal use of the foamed cotton. Detailed Embodiments

[0016] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0017] In order to illustrate the technical solutions of the present invention, specific embodiments will be used for illustration below.

[0018] In a first aspect, in an embodiment of the present invention, the present application provides a polyurethane microcellular foamed cotton resistant to heat and humidity, including a polyurethane microcellular foamed layer, a UV-curable heat and humidity resistant layer and a base layer. The polyurethane microcellular foamed layer is disposed on at least one surface of the base layer, and the UV-curable heat and humidity resistant layer is disposed on the surface of the polyurethane microcellular foamed layer facing away from the base layer.

[0019] The moisture-heat resistant polyurethane microporous foamed cotton provided in the present application has the following functions: 1) The UV light-cured moisture-heat resistant layer is arranged on the surface of the polyurethane microporous foaming layer on the side away from the base layer. The carbonyl oxygen (O=C) and ether oxygen (-O-) contained in the polyurethane microporous foaming layer can form hydrogen bonds with the UV light-cured moisture-heat resistant layer, and the polyurethane microporous foaming layer contains carbamate groups (-NHCOO-) that can form chemical bonds with the UV light-cured moisture-heat resistant layer, so that the UV light-cured moisture-heat resistant layer and the polyurethane microporous foaming layer form a strong adhesion. 2) The UV light-cured moisture-heat resistant layer has good moisture resistance and high heat resistance, and is arranged on the surface of the polyurethane microporous foaming layer. During use, it effectively prevents water vapor from entering the polyurethane microporous foaming layer, effectively improves the moisture-heat resistance of the foam, and prolongs the service life of the polyurethane microporous foamed cotton; at the same time, it also allows the polyurethane microporous foamed cotton to have excellent low water absorption and good hydrophobic properties. 3) The three-layer structure of the polyurethane microporous foam makes it difficult for the foam to stick when it is rolled out; under high temperature and high humidity conditions, the foam structure can maintain excellent dimensional stability and will not shrink or deform, thus avoiding serious problems such as separation, degumming, cracking, and wrinkling between the composite layer materials. 4) The pores in the polyurethane microporous foam layer are evenly distributed, which makes the foam have excellent rebound performance and high rebound rate, which can effectively avoid deformation after long-term use and extrusion, thus ensuring the normal use of the foam.

[0020] In some embodiments, the raw materials of the polyurethane microporous foam layer include component A and component B, wherein component A includes a polyether polyol mixture and a modified homogenizing agent, wherein the modified homogenizing agent includes a polyether-modified polysiloxane compound; and component B includes an isocyanate compound; The raw material of the UV light-curable moisture-resistant layer includes polyurethane acrylate.

[0021] The specific component A includes a polyether polyol mixture, and component B includes an isocyanate compound. The polyether polyol mixture can form a dense-structured polyurethane with the isocyanate compound, and the generated polyurethane contains carbonyl oxygen (O=C), ether oxygen (-O-), and urethane groups (-NHCOO-). The raw material of the UV-curable moisture and heat resistant layer includes polyurethane acrylate. During the photocuring process, polyurethane acrylate will form a dense crosslinked network, containing a large number of urethane bonds (-NH-CH3). On the one hand, -N-H- in the urethane bond will form hydrogen bonds with the carbonyl oxygen (O=C) and ether oxygen (-O-) in the polyurethane in the polyurethane microcellular foaming layer; on the other hand, -N-H- in the urethane bond (-NHCOO-) in polyurethane acrylate will also form chemical bonds with the remaining isocyanate in the polyurethane microcellular foaming layer. Under the simultaneous action of covalent bonds and hydrogen bonds, the UV-curable moisture and heat resistant layer can form a strong adhesion with the polyurethane microcellular foaming layer, and the bonding force between the UV-curable moisture and heat resistant layer and the polyurethane microcellular foaming layer is strong.

[0022] According to the principle of like dissolves like, the polyurethane acrylate contained in the UV-curable moisture and heat resistant layer has a similar structure to the polyurethane in the polyurethane microcellular foaming layer, which can improve the combination between polar groups and intermolecular forces, forming a strong physical adsorption force and providing good adhesion between the UV-curable moisture and heat resistant layer and the polyurethane microcellular foaming layer.

[0023] The modified foam stabilizer includes polyether-modified polysiloxane compounds, which helps to foam evenly when components A and B are mixed and foamed, so that the cell holes in the polyurethane microcellular foaming layer are evenly distributed, making the foam have excellent resilience performance, effectively avoiding the problem of deformation after long-term use and extrusion, and ensuring the normal use of the foam.

[0024] In some embodiments, the polyether polyol mixture includes a first polyether polyol, a second polyether polyol modified with styrene and acrylonitrile. The hydroxyl value of the first polyether polyol is 30 - 100 mgKOH / g, and the hydroxyl value of the second polyether polyol is 20 - 100 mgKOH / g; the mass ratio of the first polyether polyol to the second polyether polyol is (7.5 - 8.5):(1.5 - 2.5).

[0025] Specifically, the hydroxyl value of the first polyether polyol can be in the following ranges: 30-40 mgKOH / g, 40-50 mgKOH / g, 50-60 mgKOH / g, 60-70 mgKOH / g, 70-90 mgKOH / g, or 90-100 mgKOH / g. The hydroxyl value of the second polyether polyol can be in the following ranges: 20-30 mgKOH / g, 30-40 mgKOH / g, 40-50 mgKOH / g, 50-60 mgKOH / g, 60-70 mgKOH / g, 70-90 mgKOH / g, or 90-100 mgKOH / g. Specifically, the mass ratio of the first polyether polyol to the second polyether polyol can be 7.5:1.5, 7.5:1.8, 7.5:2.0, 7.5:2.2, 7.5:2.5, 8.0:1.5, 8.0:2.2, 8.0:2.5, 8.3:2.0, 8.5:2.5, etc., as long as the mass ratio of the first polyether polyol to the second polyether polyol is within the range of (7.5-8.5):(1.5-2.5).

[0026] When the molar ratio of the first polyether polyol to the second polyether polyol is lower than the range of (7.5-8.5):(1.5-2.5), the crosslinking density of the polyether polyol and the isocyanate decreases, the tensile strength of the foam decreases, and the permanent compression set is high.

[0027] The second polyether polyol modified with styrene and acrylonitrile not only contains ether bonds and hydroxyl groups, but also contains rigid benzene rings and cyano groups, increasing the rigidity and polarity of the molecular chain and improving the crosslinking density of the polyurethane.

[0028] In some embodiments, the first polyether polyol includes polyether polyol a and polyether polyol b. The hydroxyl value of polyether polyol a is 26-30 mgKOH / g, and the functionality is 2; the hydroxyl value of polyether polyol b is 26-30 mgKOH / g, and the functionality is 3; The mass ratio of polyether polyol a, polyether polyol b, and the second polyether polyol is (0.5-0.7):(0.15-0.425):(0.15-0.425).

[0029] Specifically, functionality refers to the number of hydroxyl groups in the polyether polyol. The hydroxyl value refers to the number of milligrams of potassium hydroxide (KOH) contained in 1 g of the polyether polyol.

[0030] By defining the hydroxyl value of polyether polyol a as 26-30 mgKOH / g and the functionality as 2, and the hydroxyl value of polyether polyol b as 26-30 mgKOH / g and the functionality as 3, the reaction activity is high and the reactivity with the isocyanate is stronger.

[0031] The mass ratio of the defined polyether polyol a, polyether polyol b and the second polyether polyol is in the range of (0.5 - 0.7):(0.15 - 0.4):(0.15 - 0.4), which is beneficial to preparing a polyurethane microcellular foam layer with high hardness, good mechanical strength, high tensile strength, good temperature resistance and low permanent compression set. If the mass ratio of polyether polyol a, polyether polyol b and the second polyether polyol is lower than the range of (0.5 - 0.7):(0.15 - 0.4):(0.15 - 0.4), the crosslinking density of the polyether polyol and isocyanate decreases, the tensile strength of the foam decreases, and the permanent compression set is high.

[0032] In some embodiments, the raw materials of the polyurethane microcellular foam layer include the following components: based on 100 parts of the polyether polyol mixture, the first catalyst is 0.6 - 1.0 parts, the blowing agent is 3.5 - 4.0 parts, the chain extender is 0.1 - 2.0 parts, the modified foam stabilizer is 0.8 - 1.5 parts, the isocyanate compound is 6 - 15 parts, and the initiator is 0.4 - 0.8 parts.

[0033] Specifically, the first catalyst can be the following amounts: 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1.0 parts, etc., as long as the first catalyst is within the range of 0.6 - 1.0 parts. The blowing agent can be the following amounts: 3.5 parts, 3.6 parts, 3.7 parts, 3.8 parts, 3.9 parts, 4.0 parts, etc., as long as the blowing agent is within the range of 3.5 - 4.0 parts. The chain extender can be the following amounts: 0.1 parts, 0.2 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.8 parts, 1.0 parts, etc., as long as the chain extender is within the range of 0.1 - 2.0 parts. The modified foam stabilizer can be the following amounts: 0.8 parts, 0.9 parts, 1.0 parts, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, etc., as long as the modified foam stabilizer is within the range of 0.8 - 1.5 parts. The isocyanate compound can be the following amounts: 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 12 parts, 13 parts, 15 parts, etc., as long as the isocyanate compound is within the range of 6 - 15 parts. The initiator can be the following amounts: 0.4 parts, 0.5 parts, 0.6 parts, 0.8 parts, etc., as long as the initiator is within the range of 0.4 - 0.8 parts.

[0034] In the raw materials of the polyurethane microcellular foam layer, if the content of the modified foam stabilizer is lower than the range of 0.8 - 1.5 parts, due to the too low content of the added modified foam stabilizer, the uniformity of the polyurethane microcellular foam decreases, and the obtained polyurethane microcellular foam with heat and humidity resistance has a low tensile strength, low elongation at break, high compression set, low rebound rate, high water absorption, and at the same time, the surface of the polyurethane microcellular foam with heat and humidity resistance has wrinkles, cracks and damage; if the content of the modified foam stabilizer is higher than the range of 0.8 - 1.5 parts, too many pores are formed, the water absorption of the foam increases, affecting the service life of the polyurethane microcellular foam.

[0035] Specifically, the raw materials in the polyurethane microcellular foam layer are the above components. When the A component and the B component are mixed and foamed, the pores are evenly distributed, enabling the foam to have excellent resilience performance, effectively avoiding the problem of deformation after long-term use and extrusion, ensuring the normal use of the foam; and enabling the foam to have excellent resilience performance.

[0036] In some embodiments, the blowing agent includes water, and the chain extender includes one or more of aziridine, polycarbodiimide, and diethanolamine; The first catalyst includes an organometallic catalyst, and the organometallic catalyst includes one of bismuth neodecanoate, bismuth isooctanoate, zinc neodecanoate, and zinc isooctanoate; The isocyanate compound includes one or two of isophorone diisocyanate and diphenylmethane diisocyanate; The initiator includes persulfate.

[0037] In some preferred embodiments, the persulfate includes ammonium persulfate.

[0038] In some embodiments, the raw materials of the UV-curable moisture and heat resistant layer include the following components: 20 - 50 parts of acrylate compounds, 40 - 70 parts of diluent, 3 - 7 parts of photoinitiator, and 0.1 - 3 parts of second auxiliary agent; The acrylate compounds include the polyurethane acrylate and the epoxy-modified acrylate resin; in the acrylate compounds, the ratio of the number of parts of the polyurethane acrylate to the epoxy-modified acrylate resin is (15 - 40):(5 - 10); The second auxiliary agent includes one or two of a leveling agent and a polymerization inhibitor; The diluent includes one or two of dipropylene glycol diacrylate and trimethylolpropane triacrylate; The photoinitiator includes one or two of 1-hydroxycyclohexyl phenyl ketone and 2,4,6-trimethylbenzoyl diphenylphosphine oxide.

[0039] Specifically, the acrylate compounds include the polyurethane acrylate and the epoxy-modified acrylate resin. The polyurethane acrylate contained can form hydrogen bonds and covalent bonds with the polyurethane microcellular foam layer, which is beneficial to improving the bonding strength between the UV-curable moisture and heat resistant layer and the polyurethane microcellular foam layer.

[0040] In the acrylate compound, the parts ratio of polyurethane acrylate to epoxy-modified acrylate resin is in the range of (15 - 40):(5 - 10). A better cured adhesive film can be formed between the UV-curable moisture and heat resistant layer and the polyurethane microcellular foam layer, achieving excellent adhesion. If the parts ratio of polyurethane acrylate to epoxy-modified acrylate resin is lower than the range of (15 - 40):(5 - 10), due to the reduction of polyurethane acrylate, the adhesion is weak and a good adhesive film cannot be formed, resulting in an increase in water absorption. If the parts ratio of polyurethane acrylate to epoxy-modified acrylate resin is higher than the range of (15 - 40):(5 - 10), due to too much polyurethane acrylate, the adhesive film will be too hard, affecting the overall mechanical properties of the foam.

[0041] Specifically, the parts ratio of polyurethane acrylate to epoxy-modified acrylate resin can be 15:5, 15:8, 15:10, 20:9, 25:6, 28:7, 30:8, 32:6, 35:9, 37:6, 40:10, etc., as long as the parts ratio of polyurethane acrylate to epoxy-modified acrylate resin is within the range of (15 - 40):(5 - 10).

[0042] In some embodiments, the material of the base layer is one of a polymer material, a metal material, and an alloy material.

[0043] In some preferred embodiments, when the material of the base layer is a polymer material, the base layer can be one of a PET film, a PBT film, a PC film, and a PP film.

[0044] In some preferred embodiments, when the material of the base layer is, the base layer can be an aluminum film or a copper film.

[0045] In some embodiments, the thickness of the polyurethane microcellular foam layer is 0.1 mm - 1 mm; the thickness of the UV-curable moisture and heat resistant layer is 10 μm - 100 μm.

[0046] Specifically, the thickness of the polyurethane microcellular foam layer can be 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, etc., as long as the thickness of the polyurethane microcellular foam layer is within the range of 0.1 mm - 1 mm.

[0047] The thickness of the UV-curable moisture and heat resistant layer can be 10 μm, 20 μm, 40 μm, 50 μm, 60 μm, 80 μm, 90 μm, 100 μm, etc., as long as the thickness of the UV-curable moisture and heat resistant layer is within the range of 10 μm - 100 μm.

[0048] The polyurethane microporous foamed sponge with moisture and heat resistance provided by this application has a thin polyurethane microporous foamed layer. When assembled with a composite material, it has a thin thickness and occupies a small space.

[0049] In some embodiments, the adhesion between the polyurethane microporous foamed layer and the UV-curable moisture and heat resistant layer is grade 0.

[0050] The polyurethane microporous foamed layer and the UV-curable moisture and heat resistant layer are connected by hydrogen bonds and covalent bonds, resulting in strong bonding force between them. For the polyurethane microporous foamed sponge with moisture and heat resistance provided by this application, the adhesion between the polyurethane microporous foamed layer and the UV-curable moisture and heat resistant layer is grade 0.

[0051] Second, this application provides a preparation method of the above-mentioned polyurethane microporous foamed sponge with moisture and heat resistance, including the following steps: Mix the raw materials of the polyurethane microporous foamed layer evenly and then coat them on at least one side surface of the base layer, and heat and cure to obtain the polyurethane microporous foamed layer on at least one side surface of the base layer; Mix the raw materials of the UV-curable moisture and heat resistant layer evenly and then coat them on the side surface of the polyurethane microporous foamed layer facing away from the base layer, and carry out photocuring under UV light irradiation conditions to form the UV-curable moisture and heat resistant layer on the side surface of the polyurethane microporous foamed layer facing away from the base layer, thus obtaining the polyurethane microporous foamed sponge with moisture and heat resistance.

[0052] Specifically, in the step of mixing the raw materials of the polyurethane microporous foamed layer evenly, the raw materials of the polyurethane microporous foamed layer include the following components: based on 100 parts of the polyether polyol mixture, the first catalyst is 0.6 - 1.0 parts, the foaming agent is 3.5 - 4.0 parts, the chain extender is 0.1 - 2.0 parts, the modified foam stabilizer is 0.8 - 1.5 parts, the isocyanate compound is 6 - 15 parts, and the initiator is 0.4 - 0.8 parts.

[0053] In the step of mixing the raw materials of the UV-curable moisture and heat resistant layer evenly, the raw materials of the UV-curable moisture and heat resistant layer include the following components: 20 - 50 parts of acrylate compounds, 40 - 70 parts of diluents, 3 - 7 parts of photoinitiators, and 0.1 - 3 parts of second auxiliaries.

[0054] After the step of mixing the raw materials of the polyurethane microporous foamed layer evenly and then coating them on at least one side surface of the base layer, and heating and curing to obtain the polyurethane microporous foamed layer on at least one side surface of the base layer, an automatic thickness detector can be used to test the thickness of the polyurethane microporous foamed layer. Similarly, an automatic thickness detector can also be used to test the thickness of the UV-curable moisture and heat resistant layer.

[0055] After the polyurethane microcellular foamed sponge with process parameters meeting the requirements and being resistant to damp heat is prepared, subsequent processes such as trimming and winding can be carried out to obtain the polyurethane microcellular foamed sponge that meets the requirements and is resistant to damp heat.

[0056] In the preparation method of the polyurethane microcellular foamed sponge provided by this application, the polyurethane microcellular foaming layer is obtained by heat curing, and the UV light-cured damp-heat-resistant layer is directly obtained by UV light curing. The process is simple and the cost is relatively low, which is beneficial to production line production and can be widely promoted and applied.

[0057] In some embodiments, the temperature of the heat curing is 115 - 120 °C, and the time of the heat curing is 15 - 20 min; in the step of photo-curing under UV light irradiation conditions, the photo-curing time is 1 - 3 s.

[0058] Specifically, the temperature of the heat curing can be 115 °C, 116 °C, 118 °C, 120 °C, 117 °C, 119 °C, etc., as long as the temperature of the heat curing is within the range of 115 - 120 °C. The time of the heat curing can be 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, etc., as long as the time of the heat curing is within the range of 15 - 20 min.

[0059] The temperature of the heat curing is 115 - 120 °C, and the time of the heat curing is 15 - 20 min, which is beneficial for the A component and the B component to foam and generate a polyurethane microcellular foaming layer with uniform pores.

[0060] In some embodiments, in the step of photo-curing under UV light irradiation conditions, the UV light power is 80 - 300 mW / cm 2 。

[0061] Preferably, the UV light power is 300 mW / cm 2 。

[0062] In some embodiments, the raw material of the polyurethane microcellular foaming layer includes a modified foam stabilizer, and the modified foam stabilizer includes a polyether-modified polysiloxane compound. The preparation of the modified foam stabilizer including the polyether-modified polysiloxane compound includes the following steps; The preparation method of the polyether-modified polysiloxane compound includes the following steps: Prepare a polysiloxane compound of low hydrogen-containing silicone oil: high hydrogen-containing silicone oil, cyclic siloxane compounds, linear siloxane compounds and a second catalyst are added to a reaction vessel, and the reaction is carried out at 60 - 65 °C for 3 - 5 h. After the reaction is completed, a first post-treatment is carried out to obtain a polysiloxane compound of low hydrogen-containing silicone oil; the mass fraction of active hydrogen in the polysiloxane compound of low hydrogen-containing silicone oil is 0.08% - 1%; Preparation of polyether-modified polysiloxane compounds: dehydrate the polysiloxane compounds of the low hydrogen-containing silicone oil, non-ionic surfactant and organic solvent, then add a third catalyst and carry out a heating reaction under a protective atmosphere. The heating reaction temperature is 100-120 °C, the heating reaction time is 3-5 h, and a second post-treatment is carried out after the heating reaction to obtain the polyether-modified polysiloxane compounds; the non-ionic surfactant includes allyl-terminated polyoxyalkylene ether; The second catalyst includes inorganic acid catalysts; The third catalyst is a first mixed solution composed of chloroplatinic acid and isopropanol, and the mass fraction of chloroplatinic acid in the first mixed solution is 4-7%; The cyclic siloxane compounds include dimethylcyclosiloxane; The linear siloxane compounds include hexamethyldisilane.

[0063] The preparation method of the polyether-modified polysiloxane compounds provided by this application has a simple process and low cost.

[0064] In some embodiments, the reaction is carried out at 60-65 °C for 3-5 h. After the reaction, in the first post-treatment step, the first post-treatment includes the following steps: after the reaction, a second mixed solution is obtained, the second mixed solution is cooled to the range of 20-30 °C, a pH regulator is added to adjust the pH of the second mixed solution, and then filtration and distillation are carried out to obtain the polysiloxane compounds of the low hydrogen-containing silicone oil.

[0065] The pH regulator includes sodium bicarbonate.

[0066] The distillation includes the following steps: vacuum distillation at 110 °C to remove low-boiling substances.

[0067] In some preferred embodiments, the mass fraction of active hydrogen in the high hydrogen-containing silicone oil is 1.5-1.6%; the mass fraction of active hydrogen in the polysiloxane compounds of the low hydrogen-containing silicone oil is 0.09%.

[0068] In some embodiments, the mass ratio of cyclic siloxane compounds, high hydrogen-containing silicone oil, and linear siloxane compounds is (40-100):(3-9):(1-3).

[0069] In some preferred embodiments, the mass ratio of cyclic siloxane compounds, high hydrogen-containing silicone oil, and linear siloxane compounds is 51:3:(1-3).

[0070] In some embodiments, the mass ratio of the second catalyst to the cyclic siloxane compounds is (1-3):100.

[0071] In some preferred embodiments, the second catalyst includes concentrated sulfuric acid.

[0072] When the cyclic siloxane compound is selected from dimethylcyclosiloxane and the linear siloxane compound is selected from hexamethyldisiloxane, under the action of a second catalyst, high hydrogen content silicone oil, dimethylcyclosiloxane, and hexamethyldisiloxane react to form polydimethylsiloxane of low hydrogen content silicone oil.

[0073] It should be noted that high hydrogen content silicone oil and allyl-terminated polyoxyalkylene ether can be obtained by purchase. For example, the high hydrogen content silicone oil of Jinan Ruiyuan Chemical Co., Ltd. has a mass fraction of active hydrogen of 1.56%. The allyl-terminated polyoxyalkylene ether of Jiangsu Haian Petrochemical Factory has a molecular weight of 1200, hydroxyl value: 45 ± 8 mg KOH / g, acid value: ≤ 0.3 mg KOH / g.

[0074] The reaction principle for preparing polyether-modified polysiloxane compounds is that under the action of a third catalyst, the Si-H groups in the polysiloxane compounds of low hydrogen content silicone oil can undergo a hydrosilylation reaction with the carbon-carbon double bonds in the allyl-terminated polyoxyalkylene ether to obtain Si-C type polyether-modified polysiloxane.

[0075] The dehydration operation of the polysiloxane compound, non-ionic surfactant, and solvent includes the following steps: subjecting the polysiloxane compound, non-ionic surfactant, and organic solvent to azeotropic dehydration.

[0076] The organic solvent includes aromatic organic solvents.

[0077] The aromatic organic solvents include toluene.

[0078] In some embodiments, the mass ratio of platinum in the third catalyst to the mass of the polysiloxane compound is (1 - 5): 100.

[0079] The third catalyst is a first mixed solution composed of chloroplatinic acid and isopropanol. Among them, chloroplatinic acid is used as a catalyst for hydrogenation reactions, oxidation reactions, and hydrogenation reactions, etc.; isopropanol has good volatility and can be quickly evaporated after the reaction to obtain a pure product. Isopropanol can dissolve chloroplatinic acid and is removed by rapid evaporation after the reaction.

[0080] In some preferred embodiments, the mass fraction of chloroplatinic acid in the first mixed solution is 5%.

[0081] In some embodiments, the protective atmosphere includes a protective gas, and the protective gas includes one of nitrogen and noble gases.

[0082] Preferably, the protective gas is nitrogen.

[0083] In some embodiments, the heating reaction temperature is 100~120°C, and the heating reaction time is 3~5 h. The heating reaction temperature can be 100°C, 102°C, 103°C, 105°C, 106°C, 107°C, 109°C, 110°C, 113°C, 115°C, 117°C, 118°C, 120°C, etc., as long as the heating reaction temperature is within the range of 100~120°C.

[0084] The heating reaction time can be 3 h, 3.5 h, 4.0 h, 4.5 h, 5 h, etc., as long as the heating reaction time is within the range of 3~5 h.

[0085] In some embodiments, after the heating reaction is completed, a second post-treatment is carried out to obtain the polyether-modified polysiloxane compound, which includes the following steps: after the heating reaction is completed, a third mixed solution is obtained, and the third mixed solution is heated to remove the organic solvent to obtain the polyether-modified polysiloxane compound.

[0086] In some embodiments, the molar ratio of the polysiloxane compound of low hydrogen content silicone oil to the non-ionic surfactant is 1:(4~6).

[0087] The polyether-modified polysiloxane compound has a silicone oxygen chain as the main body, and a polyether chain segment is introduced by graft copolymerization; the silicone oxygen chain contains repeating silicon-oxygen bonds (-Si-O-Si-), providing hydrophobicity and flexibility. The other bonds of Si are replaced by methyl groups, and the two methyl groups are perpendicular to the plane where silicon and oxygen are located. The Si-C bond length is relatively large, so that the three hydrogen atoms on the two methyl groups can be spread out like an umbrella, giving it good hydrophobicity; after the silicone is modified with polyether, the grafted polyether chain segment increases the hydrophilicity of the polysiloxane, improves the hydrophobicity of the silicone, can reduce the surface tension, and enables the stable formation and growth of foam cells during the polyurethane foaming process.

[0088] In a third aspect, the present application provides an application of the above-mentioned polyurethane microcellular foam with moisture and heat resistance in the fields of buffer materials, heat insulation materials, sound absorption materials, and electronic products.

[0089] The polyurethane microcellular foam with moisture and heat resistance provided by the present application can be used in the field of buffer materials and has high resilience. For example, it can be used as a filling material for home decoration and has high resilience. When the foam is used as a heat insulation material or a sound absorption material, for example, it can be used in the construction field. When the foam is used in the field of electronic products, for example, it can be used as the packaging of electronic products, etc.

[0090] The present invention will be further described below through examples.

[0091] Example 1 S1: Prepare a modified foam stabilizer polyether-modified polysiloxane S11: Prepare polydimethylsiloxane with low hydrogen content silicone oil: 112.5 g of dimethylcyclosiloxane mixture, 6.5 g of high hydrogen content silicone oil (active hydrogen mass fraction is 1.56%), and 2.2 g of hexamethyldisiloxane are added to a reaction kettle. 2 g of the second catalyst concentrated sulfuric acid is added, and the reaction is carried out at 60 °C for 3 h. Then it is cooled to room temperature (25 ± 5 °C), neutralized with sodium bicarbonate, filtered by suction, and vacuum distilled at 110 °C to remove low-boiling substances, obtaining polydimethylsiloxane of low hydrogen content silicone oil with an active gas mass fraction of 0.09%. The mass ratio of dimethylcyclosiloxane mixture, high hydrogen content silicone oil, and hexamethyldisiloxane is 51:3:1, and the mass ratio of the second catalyst concentrated sulfuric acid to dimethylcyclosiloxane is 1.78:100.

[0092] S12: Preparation of polyether-modified polysiloxane Obtain raw materials: Allyl-terminated polyoxyalkylene ether is purchased from Jiangsu Haian Petrochemical Factory, with a molecular weight of 1200, hydroxyl value: 45 ± 8 mg KOH / g, acid value: ≤ 0.3 mg KOH / g. The third catalyst is chloroplatinic acid-isopropanol solution, in which the mass fraction of chloroplatinic acid in the chloroplatinic acid-isopropanol solution is 5%. The organic solvent is toluene.

[0093] In a three-necked flask, first, 10 g of the polydimethylsiloxane of low hydrogen content silicone oil prepared in step S12, 43.2 g of allyl-terminated polyether, and toluene with a mass fraction of 25% are subjected to azeotropic dehydration, and then the third catalyst chloroplatinic acid-isopropanol solution is added. It is heated to 100 °C under a nitrogen atmosphere and reacted for 4 h; after evaporating the solvent, polyether-modified polysiloxane is obtained. Among them, the mass ratio of platinum in the third catalyst to the mass of the polydimethylsiloxane of low hydrogen content silicone oil is 1:100, and the molar ratio of the polydimethylsiloxane of low hydrogen content silicone oil to allyl-terminated polyether is 1:(4 - 6).

[0094] S2: Preparation of a polyurethane microcellular foaming layer on the substrate surface The substrate is a PET film.

[0095] Preparation of component A raw materials: Polyether polyol a is Bluestar Dongda Polyether LD83EA, polyether polyol b is Bluestar Dongda 10LD28XM, the second polyether polyol is Bluestar Dongda Polyether Polyol HPOP40, foaming agent water, chain extender diethanolamine, the first catalyst is bismuth neodecanoate, bismuth isooctanoate, zinc neodecanoate, and zinc isooctanoate; the foam stabilizer is the polyether-modified polysiloxane prepared in step S1.

[0096] Preparation of component B raw materials: The isocyanate compound is isophorone diisocyanate and diphenylmethane diisocyanate, and the initiator is ammonium persulfate.

[0097] S22: Preparation of component A: 60 parts of 10LD28XM, 20 parts of 10LD83E, 20 parts of HPOP40, 4 parts of water, 1 part of diethanolamine, 0.2 parts of bismuth neodecanoate, 0.25 parts of bismuth isooctanoate, 0.3 parts of zinc neodecanoate, 0.3 parts of zinc isooctanoate, and 1 part of polyether-modified polysiloxane are mixed evenly to obtain material A; S23: Preparation of component B: 5 parts of isophorone diisocyanate, 3 parts of diphenylmethane diisocyanate, and 0.04 parts of ammonium persulfate were mixed to obtain material B.

[0098] S24: Component A and component B are mixed evenly in a mass ratio of 1:1, coated on the surface of the PET film with a coating thickness of 0.5 mm, and heated and cured at 120° C. for 15 minutes to prepare a polyurethane microporous foam layer on the surface of the substrate.

[0099] S3: Preparation of UV light-cured moisture-resistant layer on the surface of the polyurethane microporous foam layer away from the substrate S31: Raw material preparation of UV light curing heat and moisture resistant layer: The acrylate compounds are epoxy-modified acrylic resin from Sartomer and polyurethane acrylate with the model number of EBECRYL 270 from Allnex Chemical; The diluent is dipropylene glycol diacrylate resin with model number EM222TF of China Changxing Company and trimethylolpropane triacrylate with model number EM231TF of China Changxing Company; The photoinitiator is 1-hydroxycyclohexyl phenyl ketone with the model number Omnirad184 from Agenmon Company and 2,4,6-trimethylbenzoyldiphenylphosphine oxide with the model number Omnirad TPO from Agenmon Company; The leveling agent is BYK-350 from Germany; The inhibitor is hydroquinone from Eastman, USA.

[0100] S32: 25 parts of epoxy modified acrylic resin; 10 parts of polyurethane acrylate; 50 parts of dipropylene glycol diacrylate resin, 10 parts of trimethylolpropane triacrylate, 4 parts of 1-hydroxycyclohexyl phenyl ketone, 1 part of 2,4,6-trimethylbenzoyl diphenyl phosphine oxide, 0.5 parts of leveling agent and 0.1 parts of polymerization inhibitor are placed in a stirrer and dispersed at high speed for 30 minutes at room temperature; stirring is stopped to obtain a UV light-cured moisture-heat resistant mixture. The ratio of polyurethane acrylate to epoxy modified acrylic resin is 2:5.

[0101] S33: Coat the UV-cured moisture and heat resistant mixture obtained in step S32 on the surface of the polyurethane microcellular foam layer on the side facing away from the PET film, with a coating thickness of 100 microns, and cure it under the irradiation of a high-pressure mercury lamp. The power of the high-pressure mercury lamp is 1000 W, and the light curing time is 3 s. After the light curing is completed, a UV-cured moisture and heat resistant layer is prepared on the surface of the polyurethane microcellular foam layer on the side facing away from the PET film, and a moisture and heat resistant polyurethane microcellular foam is prepared.

[0102] Example 2 Most steps of this example are the same as those of Example 1. The differences are as follows: In the preparation of component A in step S22, 70 parts of 10LD28XM, 15 parts of 15 parts of 10LD83E, and 15 parts of HPOP40; the rest are the same as those of Example 1.

[0103] Example 3 Most steps of this example are the same as those of Example 1. The differences are as follows: In the preparation of component A in step S22, 50 parts of 50 parts of 10LD28XM, 25 parts of 25 parts of 10LD83E, and 25 parts of HPOP40; the rest are the same as those of Example 1.

[0104] Example 4 Most steps of this example are the same as those of Example 1. The differences are as follows: In the preparation of component A in step S22, 40 parts of 40 parts of 10LD28XM, 30 parts of 10LD83E, and 30 parts of HPOP40; the rest are the same as those of Example 1.

[0105] Example 5 Most steps of this example are the same as those of Example 1. The differences are as follows: In the preparation of component A in step S22, the polyether-modified polysiloxane is 0.8 part; the rest are the same as those of Example 1.

[0106] Example 6 Most steps of this example are the same as those of Example 1. The differences are as follows: In the preparation of component A in step S22, 1.2 parts of polyether-modified polysiloxane material; the rest are the same as those of Example 1.

[0107] Example 7 Most steps of this example are the same as those of Example 1. The differences are as follows: In the preparation of component A in step S22, the polyether-modified polysiloxane is 1.5 parts; the rest are the same as those of Example 1.

[0108] Example 8 Most steps of this example are the same as those of Example 1. The differences are as follows: In step S32, 15 parts of epoxy-modified acrylate resin, 5 parts of polyurethane acrylate, and 20 parts of trimethylolpropane triacrylate are added, and the rest is the same as that of Example 1. Among them, the ratio of the parts of polyurethane acrylate to epoxy-modified acrylate resin is 1:3.

[0109] Example 9 Most steps of this example are the same as those of Example 1. The differences are as follows: In step S32, 5 parts of polyurethane acrylate and 15 parts of trimethylolpropane triacrylate are added, and the rest is the same as that of Example 1. Among them, the ratio of the parts of polyurethane acrylate to epoxy-modified acrylate resin is 1:5.

[0110] Example 10 Most steps of this example are the same as those of Example 1. The differences are as follows: In step S32, 35 parts of epoxy-modified acrylate resin, 5 parts of polyurethane acrylate, and 40 parts of dipropylene glycol diacrylate are added, and the rest is the same as that of Example 1. Among them, the ratio of the parts of polyurethane acrylate to epoxy-modified acrylate resin is 5:2.

[0111] Example 11 Most steps of this example are the same as those of Example 1. The differences are as follows: In step S32, 40 parts of epoxy-modified acrylate resin, 10 parts of polyurethane acrylate, and 30 parts of dipropylene glycol diacrylate are added, and the rest is the same as that of Example 1. Among them, the ratio of the parts of polyurethane acrylate to epoxy-modified acrylate resin is 1:4.

[0112] Example 12 Most steps of this example are the same as those of Example 1. The differences are as follows: In the preparation of component A in step S22, polyether-modified polysiloxane is not added, and the rest is the same as that of Example 1.

[0113] Example 13 Most steps of this example are the same as those of Example 1. The differences are as follows: In the preparation of component A in step S22, 2.0 parts of polyether-modified polysiloxane are added.

[0114] Example 14 Most steps of this example are the same as those of Example 1. The differences are as follows: In step S31, the raw material preparation step of the UV-curable moisture and heat resistant layer, the acrylate compound is the epoxy-modified acrylate resin of Sartomer Company; in step S32, 25 parts of epoxy-modified acrylate resin are added, and there is no polyurethane acrylate. Among them, the ratio of the parts of polyurethane acrylate to epoxy-modified acrylate resin is 0:25.

[0115] Example 15 Most steps of this example are the same as those of Example 1. The differences are as follows: in step S32, the epoxy-modified acrylic resin is 4 parts, and the polyurethane acrylate is 40 parts, which are the same as those in Example 1. Among them, the ratio of the parts of polyurethane acrylate to epoxy-modified acrylic resin is 40:4.

[0116] Example 16 Most steps of this example are the same as those of Example 1. The differences are as follows: in the step of preparing polydimethylsiloxane of low hydrogen-containing silicone oil in S11, the reaction temperature is 65 °C and the reaction time is 3 h; in the step of preparing polyether-modified polysiloxane in S12, it is heated to 120 °C under a nitrogen atmosphere and reacts for 3 h. The rest are the same as those in Example 1.

[0117] Comparative Example 1 Most steps of this comparative example are the same as those of Example 1. The difference is that there is no step S3 in Comparative Example 1, and the rest are the same as those in Example 1.

[0118] Comparative Example 2 Most steps of this comparative example are the same as those of Example 1. The differences are as follows: there is no step S3 in Comparative Example 2, and at the same time, in the preparation of component A in step S22, polyether-modified polysiloxane is not added, and the rest are the same as those in Example 1.

[0119] Performance Test The moisture and heat resistant polyurethane microcellular foamed sponge prepared in the above examples and comparative examples was tested as follows.

[0120] 1) Resilience: At room temperature, the resilience rate was measured with a universal tensile machine. According to the ASTM D-412 specification, the tensile speed was 50 mm / min, and the sample was cyclically stretched five times, and the deformation recovery rate R (%) was calculated using the following formula: R = In the formula, R represents the deformation recovery rate, L0 represents the original length of the moisture and heat resistant polyurethane microcellular foamed sponge, L1 represents the length after elongation by an external force, and L2 represents the length after removing the external force. The results of R were filled into Table 1, and the value of R was the resilience rate.

[0121] 2) Tensile strength According to the GB / T6344-2008 test standard, the moisture and heat resistant polyurethane microcellular foamed sponge was cut into dumbbell-shaped specimens (taking the "1" type dumbbell specimen in the standard) with a slicing machine. The distance between the upper and lower clamps was set to 62.5 mm. The sample was placed between the upper and lower clamps of the tensile machine, and the tensile rate was adjusted to 500 mm / min. The number of samples should meet the requirement that at least 5 samples break within the gauge length and at least 5 specimens are required.

[0122] 3) Elongation at break According to the test standard of GB / T6344-2008, the heat and humidity resistant polyurethane microcellular foamed sponge is cut into dumbbell-shaped specimens with a slicing machine (take the "1" type dumbbell specimen in the standard). Set the distance between the upper and lower clamps to 62.5 mm. Place the sample between the upper and lower clamps of the tensile machine, adjust the tensile rate to 500 mm / min. The number of samples should meet the requirement that at least 5 samples break within the gauge length, with at least 5 specimens in total.

[0123] 4) Water absorption rate The water absorption rate of the heat and humidity resistant polyurethane microcellular foamed sponge is determined by cutting each sample into the same size, weighing and recording the weight (W1). Then mark the cut samples and soak them in water for 96 h. After that, dry the water on the surface of the film with filter paper, weigh and record the weight of the sample at this time (W2). Each sample is tested at least 3 times. The formula for the water absorption rate W (%) is as follows: W (%) = (W2 - W1) / W1 × 100%.

[0124] 5) Permanent compression deformation According to the test standard of ASTM D 3574, cut the heat and humidity resistant polyurethane microcellular foamed sponge into 50×50 mm, stack it to a thickness of about 10 mm (allowing multiple layers of samples to be stacked for testing). Compress the thickness by 70% with a compression fixture: ① Place it in a thermostatic and humidistatic chamber at a temperature of 85 °C and a humidity of 85%RH for 24 h; ② Place it at room temperature (25 - 30 °C) for 24 h. After the test is completed, allow the sample to recover for 30 min, then start testing the sample thickness and calculate the compression residual deformation value. Visually observe whether there are wrinkles, cracks, or damages on the surface of the heat and humidity resistant polyurethane microcellular foamed sponge.

[0125] 6) Cell uniformity Based on the microscopic observation of the cell distribution uniformity of the polyurethane microcellular foamed layer, the standard for uniformity is to take samples of the same size and observe whether there are obvious large pores and merged pores in the same area. If there are no obvious large pores and merged pores, it is determined that the cells are uniformly distributed. If there are obvious large pores and merged pores, it is determined that the cells are non-uniformly distributed. Merged pores are large pores formed by the merging of different pores.

[0126] 7) Adhesion According to the national standard GB / T9286-1998, test the adhesion grade between the polyurethane microcellular foamed layer and the UV-curable heat and humidity resistant layer in the foam.

[0127] The above test results are shown in Table 1.

[0128] Table 1 As can be seen from Table 1, when comparing Example 1 with Comparative Example 1, there is no UV-curable moisture and heat resistant layer in Comparative Example 1, and the water absorption rate of Comparative Example 1 is relatively high. This shows that setting a UV-curable moisture and heat resistant layer on the surface of the polyurethane microcellular foam layer away from the substrate can effectively improve the moisture and heat resistance of the foam, reduce the water repellency rate, and achieve good water repellency performance.

[0129] When comparing Example 1, Examples 5 - 7, Example 12, and Example 13 with Comparative Example 2, there is no polyether-modified polysiloxane and no UV-curable moisture and heat resistant layer in Comparative Example 2. The elongation at break is low, the compression set is high, the resilience rate is low, the water absorption rate is high, and there are wrinkles, cracks, and damages on the surface of the moisture and heat resistant polyurethane microcellular foam, and the cell distribution is uneven; there is no polyether-modified polysiloxane in Example 12, and the tensile strength of Example 12 is relatively low, the elongation at break is low, the compression set is high, the resilience rate is low, the water absorption rate is high, and the cell distribution is uneven; the content of polyether-modified polysiloxane in Example 13 is higher than 0.8 - 1.5 parts, the permanent compression deformation is slightly high, and the water absorption rate is slightly high. This shows that adding 0.8 - 1.5 parts of polyether-modified polysiloxane to Component A can achieve uniform foaming when Component A and Component B are mixed and foamed. The cells of the obtained polyurethane microcellular foam layer are evenly distributed, the tensile strength and elongation at break of the foam are improved, the compression set is reduced, and the resilience rate is high.

[0130] When comparing Example 1 - 3 with Example 4, the content of polyether polyol a added to Component A is reduced, and the mass ratio of polyether polyol a, polyether polyol b, and the second polyether polyol is lower than the range of (0.5 - 0.7):(0.15 - 0.425):(0.15 - 0.425), and the molar ratio of the first polyether polyol to the second polyether polyol is lower than the range of (7.5 - 8.5):(1.5 - 2.5). The obtained moisture and heat resistant polyurethane microcellular foam has low tensile strength and high compression set. This shows that when the mass ratio of polyether polyol a, polyether polyol b, and the second polyether polyol added to Component A is in the range of (0.5 - 0.7):(0.15 - 0.4):(0.15 - 0.4), and the molar ratio of the first polyether polyol to the second polyether polyol is in the range of (7.5 - 8.5):(1.5 - 2.5), foaming with the isocyanate compound of Component B can increase the crosslinking density and help improve the tensile strength of the foam and reduce the compression set.

[0131] Comparing Example 1, Examples 8 - 11 with Examples 14 and 15, in the raw materials of the UV - curable moisture - and heat - resistant layer in Example 14, there is no polyurethane acrylate, resulting in a low tensile strength and an adhesion level of only Grade 1. In Example 15, the ratio of the parts of polyurethane acrylate and epoxy - modified acrylate resin is higher than (15~40):(5~10). Due to too much polyurethane acrylate, the adhesive film will be too hard, affecting the overall mechanical properties of the foam. It shows that when the ratio of the parts of polyurethane acrylate and epoxy - modified acrylate resin is in the range of (15~40):(5~10), a good - cured adhesive film is formed between the UV - curable moisture - and heat - resistant layer and the polyurethane microcellular foam layer, with good adhesion and without affecting the mechanical properties of the polyurethane microcellular foam layer.

[0132] As can be seen from Example 1 and Example 16, in the step of preparing polydimethylsiloxane with low - hydrogen - containing silicone oil, the reaction temperature is 60~65°C and the reaction time is 3~5 h. In the step of preparing polyether - modified polysiloxane, the reaction temperature is 100~120°C and the reaction time is 3~5 h. The prepared polyether - modified polysiloxane has a high purity. When the A component and the B component are mixed and foamed, the foaming is uniform, and the cell holes of the polyurethane microcellular foam layer are evenly distributed, enabling the foam to have excellent resilience performance and effectively avoiding the problem of deformation after long - term use and extrusion.

[0133] The above examples are only used to illustrate the technical solutions of the present invention, not to limit it. Although the present invention has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or perform equivalent replacements for some of the technical features. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A heat-resistant polyurethane microporous foamed cotton, characterized in that: It comprises a polyurethane microporous foam layer, a UV light-cured moisture-resistant layer and a base layer, wherein the polyurethane microporous foam layer is arranged on at least one side of the base layer, and the UV light-cured moisture-resistant layer is arranged on the side of the polyurethane microporous foam layer away from the base layer.

2. The heat-resistant polyurethane microporous foamed cotton according to claim 1, characterized in that: The raw materials of the polyurethane microporous foaming layer include component A and component B, wherein the component A includes a polyether polyol mixture and a modified homogenizing agent, wherein the modified homogenizing agent includes a polyether-modified polysiloxane compound; and the component B includes an isocyanate compound. The raw material of the UV light-curable moisture-resistant layer includes polyurethane acrylate.

3. The heat-resistant polyurethane microporous foamed cotton according to claim 2, characterized in that: The polyether polyol mixture comprises a first polyether polyol and a second polyether polyol modified by styrene and acrylonitrile, wherein the hydroxyl value of the first polyether polyol is 30-100 mgKOH / g, and the hydroxyl value of the second polyether polyol is 20-100 mgKOH / g; and the mass ratio of the first polyether polyol to the second polyether polyol is (7.5-8.5):(1.5-2.5).

4. The heat-resistant polyurethane microporous foamed cotton according to claim 2, characterized in that: The raw materials of the polyurethane microporous foaming layer include the following components: based on 100 parts of the polyether polyol mixture, 0.6-1.0 parts of the first catalyst, 3.5-4.0 parts of the blowing agent, 0.1-2.0 parts of the chain extender, 0.8-1.5 parts of the modified foaming agent, 6-15 parts of the isocyanate compound, and 0.4-0.8 parts of the initiator; The foaming agent includes water, and the chain extender includes one or more of aziridine, polycarbodiimide, and diethanolamine; The first catalyst comprises an organic metal catalyst, and the organic metal catalyst comprises one of bismuth neodecanoate, bismuth isooctanoate, zinc neodecanoate, and zinc isooctanoate; The isocyanate compound includes one or two of isophorone diisocyanate and diphenylmethane diisocyanate; The initiator includes a persulfate.

5. The heat-resistant polyurethane microporous foamed cotton according to claim 2, characterized in that: The raw materials of the UV light-curable moisture-resistant layer include the following components: 20-50 parts of acrylate compound, 40-70 parts of diluent, 3-7 parts of photoinitiator, and 0.1-3 parts of second auxiliary agent; The acrylate compound includes the polyurethane acrylate and epoxy-modified acrylic resin; In the acrylic ester compound, the ratio of polyurethane acrylate to epoxy modified acrylic resin is (15-40): (5-10); The second auxiliary agent includes one or both of a leveling agent and an inhibitor; The diluent includes one or two of dipropylene glycol diacrylate resin and trimethylolpropane triacrylate; The photoinitiator includes one or two of 1-hydroxycyclohexyl phenyl ketone and 2,4,6-trimethylbenzoyldiphenylphosphine oxide.

6. The heat-resistant polyurethane microporous foamed cotton according to claim 1, characterized in that: The material of the base layer is one of polymer material, metal material and alloy material; The thickness of the polyurethane microporous foaming layer is 0.1 mm to 1 mm; the thickness of the UV light-cured moisture-resistant layer is 10 μm to 100 μm; Or, the adhesion between the polyurethane microporous foaming layer and the UV light-cured moisture-heat-resistant layer is level 0.

7. A method for preparing the heat-resistant polyurethane microporous foamed cotton according to any one of claims 1 to 6, characterized in that: The following steps are involved: The raw materials of the polyurethane microporous foam layer are mixed evenly and then coated on at least one side of the surface of the base layer, and heated and cured to obtain the polyurethane microporous foam layer on at least one side of the surface of the base layer; The raw materials of the UV light-curable moisture-heat resistant layer are mixed evenly and then coated on the surface of the polyurethane microporous foam layer on the side away from the base layer, and light-cured under UV light conditions to form the UV light-curable moisture-heat resistant layer on the surface of the polyurethane microporous foam layer on the side away from the base layer to obtain the moisture-heat resistant polyurethane microporous foam cotton.

8. The method for preparing the heat-resistant polyurethane microporous foamed cotton according to claim 7, characterized in that: The temperature of the heating curing is 115-120° C., and the time of the heating curing is 15-20 minutes; in the curing step under UV light conditions, the curing time is 1-3 seconds.

9. The method for preparing the heat-and-humidity resistant polyurethane microporous foamed cotton according to claim 7, characterized in that: The raw material of the polyurethane microporous foaming layer includes a modified foaming agent, and the modified foaming agent includes a polyether-modified polysiloxane compound. The preparation of the modified foaming agent including the polyether-modified polysiloxane compound includes the following steps: Preparation of polysiloxane compounds with low hydrogen silicone oil content: adding high hydrogen silicone oil, cyclosiloxane compounds, linear siloxane compounds and a second catalyst into a reaction container, reacting at 60-65° C. for 3-5 hours, and performing a first post-treatment after the reaction to obtain polysiloxane compounds with low hydrogen silicone oil content; the mass fraction of active hydrogen in the polysiloxane compounds with low hydrogen silicone oil content is 0.08%-1%; Preparation of polyether-modified polysiloxane compounds: dehydrating the polysiloxane compound of low hydrogen silicone oil, a nonionic surfactant and an organic solvent, then adding a third catalyst to carry out a heating reaction under a protective atmosphere, the heating reaction temperature is 100-120° C., the heating reaction time is 3-5 hours, and after the heating reaction is completed, a second post-treatment is carried out to obtain the polyether-modified polysiloxane compound; the nonionic surfactant includes terminal allyl polyoxyalkylene ether; The second catalyst comprises an inorganic acid catalyst; The third catalyst is a first mixed solution composed of chloroplatinic acid and isopropanol, wherein the mass fraction of chloroplatinic acid in the first mixed solution is 4-7%; The cyclosiloxane compound includes dimethylcyclosiloxane; Linear siloxane compounds include hexamethyldisilane.

10. Application of the moisture-heat-resistant polyurethane microporous foam cotton prepared by the preparation method of the moisture-heat-resistant polyurethane microporous foam cotton described in any one of claims 1 to 6 or the moisture-heat-resistant polyurethane microporous foam cotton described in any one of claims 7 to 9 in the fields of cushioning materials, thermal insulation materials and electronic products.

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