PUR for seamless dispensing of underwear and preparation method of PUR

Abstract

The invention relates to the technical field of hot melt adhesives, and particularly discloses PUR for seamless dispensing of underwear and a preparation method of the PUR. The PUR is prepared from the following raw material components in parts by weight: 45 to 70 parts of isocyanate, 5 to 20 parts of polycarboxylate, 5 to 10 parts of polyether polyol, 18 to 30 parts of tackifying resin, 0.5 to 2.0 parts of a catalyst, 1.0 to 2.0 parts of a chain extender, 2.0 to 5.0 parts of a cross-linking agent, 3 to 10 parts of filler, 0.5 to 1.5 parts of an antioxidant and 5 to 10 parts of high-flexibility rubber, the high-flexibility rubber comprises the following raw materials: natural rubber, a plasticizer, a tackifier and a vulcanizing agent. The PUR for seamless dispensing of the underwear, disclosed by the invention, not only has relatively good peel strength, but also has relatively good softness.

Description

Technical Field

[0001] The present application relates to the technical field of hot melt adhesives, and in particular to a PUR for seamless dispensing of underwear and a preparation method thereof. Background Art

[0002] PUR is a moisture-curing reactive polyurethane hot melt adhesive, the main component of which is a terminal isocyanate polyurethane prepolymer. PUR has excellent bonding strength, temperature resistance, chemical corrosion resistance and aging resistance, and has become one of the important varieties in the adhesive industry in recent years. It is now widely used in national economic fields such as packaging, wood processing, automobiles, textiles, electromechanical, aerospace, etc. PUR for textile composites requires good peel strength and excellent softness. In order to improve the peel strength of PUR, crystalline polyester polyols can be added or their content can be increased, and the content of MDI can also be increased to increase the hard segment content. However, the increase in the content of crystalline polyester polyols or MDI also greatly enhances the hardness of PUR after curing, which greatly reduces its softness. The decrease in the softness of PUR adhesive after curing directly leads to a significant reduction in the softness of the fabric bonded with PUR, thereby affecting the feel of the fabric and the comfort of wearing, especially having a greater negative impact on the comfort of close-fitting underwear. Summary of the invention

[0003] In order to make PUR have both good peel strength and good softness, the present application provides PUR for seamless dispensing of underwear and a preparation method thereof.

[0004] In the first aspect, the present application provides a PUR for seamless dispensing of underwear, which adopts the following technical solution: A PUR for seamless dispensing of underwear, wherein the raw materials of the PUR include the following components in parts by weight: 45-70 parts of isocyanate, 5-20 parts of polycarboxylate, 5-10 parts of polyether polyol, 18-30 parts of tackifying resin, 0.5-2.0 parts of catalyst, 1.0-2.0 parts of chain extender, 2.0-5.0 parts of cross-linking agent, 3-10 parts of filler, 0.5-1.5 parts of antioxidant, and 5-10 parts of high-flexibility rubber; the raw materials of the high-flexibility rubber include: natural rubber, plasticizer, tackifier, and vulcanizer.

[0005] By adopting the above technical solution, natural rubber itself has certain viscosity and toughness, plasticizer can reduce the hardness of colloid and improve softness, thickener improves the adhesion of colloid, vulcanizer makes colloid form cross-linked structure, thereby enhancing peel strength, so the obtained high-flexibility rubber is added to PUR, so that PUR has both good peel strength and good softness.

[0006] In a specific embodiment, the weight ratio of natural rubber, plasticizer, tackifier and vulcanizer in the high-flexibility rubber is 1: (0.2-0.4): (0.1-0.3): (0.08-0.12).

[0007] By adopting the above technical solution, the ratio of natural rubber, plasticizer, tackifier and vulcanizer is further limited, and the peel strength and softness of the obtained high-flexibility rubber can be further improved.

[0008] In a specific embodiment, the method for preparing the high-flexibility rubber comprises the following steps: Adding a plasticizer and a tackifier to natural rubber, and kneading the mixture at 80-120° C. to obtain a mixture; Then, a vulcanizing agent is added to the mixture, and vulcanization is performed at 140-160° C. to obtain a high-flexibility rubber.

[0009] By adopting the above technical solution, a plasticizer and a tackifier are first added to the natural rubber for mixing, and then a vulcanizing agent is added for vulcanization to obtain a high-flexibility rubber with high peel strength and high flexibility.

[0010] In a specific embodiment, the plasticizer includes dioctyl phthalate.

[0011] In a specific embodiment, the tackifier includes rosin resin.

[0012] By adopting the above technical solution, rosin resin, dioctyl phthalate and natural rubber all have good compatibility, which can significantly improve the viscosity and flexibility of the rubber.

[0013] In a specific embodiment, the vulcanizing agent includes a mixture of sulfur and tetramethylthiuram disulfide.

[0014] By adopting the above technical solution, sulfur has a better vulcanization effect, and tetramethylthiuram disulfide can accelerate the vulcanization reaction and improve production efficiency, while also helping to improve the viscosity and stability of rubber.

[0015] In a specific embodiment, the filler includes a mixture of carbon black and talc.

[0016] By adopting the above technical solution, carbon black can increase the internal strength and bonding strength of the rubber, talcum powder can improve the fluidity of the rubber, and can further enhance the adhesion and viscosity of the rubber. Therefore, the combination of the two further improves the peel strength of PUR.

[0017] In the second aspect, the present application provides a method for preparing PUR for seamless dispensing of underwear, which adopts the following technical solution: A method for preparing PUR for seamless dispensing of underwear comprises the following steps: Firstly, polycarboxylate and polyether polyol are stirred and mixed uniformly to obtain an oligomeric mixture; Add part of the isocyanate, the tackifying resin and part of the oligomeric mixture into a reaction kettle, stir and heat to 125-130°C, maintain for 2-3 hours, let stand for 24 hours, then add the remaining oligomeric mixture, introduce nitrogen and heat to 135°C, continue stirring for 1-2 hours, let stand, and wait until the water content is less than 500ppm to obtain a mixture A; The remaining isocyanate is melted at 130°C, and allowed to stand for 1 hour to cool to 95-105°C to obtain molten isocyanate; After the mixture A is cooled to 70-80°C, nitrogen is charged into the reactor, molten isocyanate is added and stirred, the temperature is controlled at about 100°C, stirred for 2-3 hours, and then a catalyst, a chain extender, and a cross-linking agent are added, and stirring is continued for 40 minutes to obtain a mixture B; After the mixture B is cooled to 50-70°C, fillers, antioxidants and high-soft rubber are added, stirred and mixed for 1-2 hours, and then vacuum treated for 24 hours at a vacuum degree of 5kPa-10kPa and a temperature of 100°C-120°C to obtain PUR for seamless dispensing of underwear.

[0018] By adopting the above technical scheme, the polycarboxylate and the polyether polyol are first stirred to obtain an oligomeric mixture, then part of the isocyanate, the tackifying resin, and part of the oligomeric mixture are reacted first, and then the remaining oligomeric mixture is added to obtain a mixture A, and then the molten isocyanate is added, stirred to react, and then a catalyst, a chain extender, and a cross-linking agent are added to obtain a mixture B, and finally fillers, antioxidants, and high-flexibility rubber are added to the mixture B to obtain PUR for underwear seamless dispensing with high peel strength and high softness.

[0019] In summary, the present application includes at least one of the following beneficial technical effects: 1. In the present application, the natural rubber itself has certain viscosity and toughness. The plasticizer can reduce the hardness of the colloid and improve its softness. The tackifier improves the adhesion of the colloid. The vulcanizer allows the colloid to form a cross-linked structure, thereby enhancing the peel strength. Therefore, the obtained high-flexibility rubber is added to PUR, so that PUR has both good peel strength and good softness. 2. In the present application, the rosin resin and dioctyl phthalate have good compatibility with natural rubber, which can significantly improve the viscosity and flexibility of the rubber. 3. The method of the present application is to first mix the polycarboxylate and the polyether polyol to obtain an oligomeric mixture, then react part of the isocyanate, the tackifying resin, and part of the oligomeric mixture, then add the remaining oligomeric mixture to obtain a mixture A, then add the molten isocyanate, stir to react, then add the catalyst, the chain extender, and the cross-linking agent to obtain a mixture B, and finally add fillers, antioxidants, and high-flexibility rubber to the mixture B to obtain PUR for underwear seamless dispensing with high peel strength and high softness. DETAILED DESCRIPTION

[0020] The present application is further described in detail below with reference to the embodiments.

[0021] All raw materials in the examples are commercially available.

[0022] Preparation Example Preparation Example 1 Preparation Example 1 provides a method for preparing high-flexibility rubber, comprising the following steps: Adding a plasticizer and a tackifier to natural rubber, kneading at 100° C. to obtain a mixed product; wherein the plasticizer is dioctyl phthalate; and the tackifier is rosin resin; Then, a vulcanizing agent is added to the mixture, and vulcanization is carried out at 150°C to obtain a high-flexibility rubber; wherein the weight ratio of natural rubber, plasticizer, tackifier and vulcanizing agent is 1:0.2:0.1:0.08; the vulcanizing agent is a mixture of sulfur and tetramethylthiuram disulfide, and the weight ratio of sulfur to tetramethylthiuram disulfide is 4:1.

[0023] Preparation Example 2 Preparation Example 2 provides a method for preparing a high-flexibility rubber, comprising the following steps: Adding a plasticizer and a tackifier to natural rubber, kneading at 100° C. to obtain a mixed product; wherein the plasticizer is dioctyl phthalate; and the tackifier is rosin resin; Then, a vulcanizing agent is added to the mixture, and vulcanization is carried out at 150° C. to obtain a high-flexibility rubber; wherein the weight ratio of natural rubber, plasticizer, tackifier, and vulcanizing agent is 1:0.3:0.2:0.10; the vulcanizing agent is a mixture of sulfur and tetramethylthiuram disulfide, and the weight ratio of sulfur to tetramethylthiuram disulfide is 4:1.

[0024] Preparation Example 3 Preparation Example 3 provides a method for preparing high-flexibility rubber, comprising the following steps: Adding a plasticizer and a tackifier to natural rubber, kneading at 100° C. to obtain a mixed product; wherein the plasticizer is dioctyl phthalate; and the tackifier is rosin resin; Then, a vulcanizing agent is added to the mixture, and vulcanization is carried out at 150°C to obtain a high-flexibility rubber; wherein the weight ratio of natural rubber, plasticizer, tackifier, and vulcanizing agent is 1:0.4:0.3:0.12; the vulcanizing agent is a mixture of sulfur and tetramethylthiuram disulfide, and the weight ratio of sulfur to tetramethylthiuram disulfide is 4:1.

[0025] Preparation Example 4 Preparation Example 4 provides a method for preparing a high-flexibility rubber, comprising the following steps: Adding a plasticizer and a tackifier to natural rubber, kneading at 100° C. to obtain a mixed product; wherein the plasticizer is dioctyl phthalate; and the tackifier is rosin resin; Then, a vulcanizing agent is added to the mixture, and vulcanization is carried out at 150° C. to obtain a highly flexible rubber; wherein the weight ratio of natural rubber, plasticizer, tackifier, and vulcanizing agent is 1:0.3:0.2:0.10; and the vulcanizing agent is sulfur. Example

[0026] Example 1 Example 1 provides a method for preparing PUR for seamless dispensing of underwear, comprising the following steps: First, 5 kg of polycarboxylate and 5 kg of polyether polyol are stirred and mixed uniformly to obtain an oligomeric mixture; wherein the polycarboxylate is polyhydroxyalkanoate; and the polyether polyol is polyoxypropylene glycol; 22.5 kg of isocyanate, 18 kg of tackifying resin and half of the oligomeric mixture were added into a reaction kettle, stirred and heated to 125° C., maintained for 3 hours, allowed to stand for 24 hours, and then the remaining oligomeric mixture was added, and nitrogen was introduced to raise the temperature to 135° C., stirred for 2 hours, allowed to stand, and when the water content was detected to be less than 500 ppm, a mixture A was obtained; wherein the isocyanate was diphenylmethane diisocyanate; and the tackifying resin was an acrylate resin; 22.5 kg of isocyanate was melted at 130° C., and allowed to stand for 1 hour to cool down to 95° C. to obtain molten isocyanate; wherein the isocyanate was diphenylmethane diisocyanate; After the mixture A is cooled to 70°C, nitrogen is charged into the reactor, molten isocyanate is added and stirred, the temperature is controlled at 100°C, stirred for 3 hours, and then 0.5 kg of catalyst, 1 kg of chain extender, and 2 kg of cross-linking agent are added, and stirring is continued for 40 minutes to obtain a mixture B; wherein the catalyst is diisobutyl phthalate; the chain extender is sodium 1,2-dihydroxy-3-propanesulfonate; and the cross-linking agent is N-phenyl-γ-aminopropyltrimethoxysilane; After the mixture B is cooled to 50°C, 3kg of filler, 0.5kg of antioxidant and 5kg of high-flexibility rubber in Preparation Example 1 are added, stirred and mixed for 2h, and then vacuum treated for 24h at a vacuum degree of 5kPa and a temperature of 100°C to obtain PUR for seamless dispensing of underwear; wherein the filler is a mixture of carbon black and talcum powder, and the weight ratio of carbon black to talcum powder is 1:1; the antioxidant is dithiodipropionate.

[0027] Example 2 Embodiment 2 provides a method for preparing PUR for seamless dispensing of underwear, comprising the following steps: First, 12.5 kg of polycarboxylate and 7.5 kg of polyether polyol were stirred and mixed uniformly to obtain an oligomeric mixture; wherein the polycarboxylate was polyhydroxyalkanoate; and the polyether polyol was polyoxypropylene glycol; 28 kg of isocyanate, 24 kg of tackifying resin and half of the oligomeric mixture were added into a reaction kettle, stirred and heated to 125° C., maintained for 3 hours, allowed to stand for 24 hours, and then the remaining oligomeric mixture was added, and nitrogen was introduced and heated to 135° C., stirred for 2 hours, allowed to stand, and when the water content was detected to be less than 500 ppm, a mixture A was obtained; wherein the isocyanate was diphenylmethane diisocyanate; and the tackifying resin was an acrylate resin; 29.5 kg of isocyanate was melted at 130° C., and allowed to stand for 1 hour to cool down to 95° C. to obtain molten isocyanate; wherein the isocyanate was diphenylmethane diisocyanate; After the mixture A is cooled to 70°C, nitrogen is charged into the reactor, molten isocyanate is added and stirred, the temperature is controlled to 100°C, stirred for 3 hours, and then 1.3 kg of catalyst, 1.5 kg of chain extender, and 3.5 kg of cross-linking agent are added, and stirring is continued for 40 minutes to obtain a mixture B; wherein the catalyst is diisobutyl phthalate; the chain extender is sodium 1,2-dihydroxy-3-propanesulfonate; and the cross-linking agent is N-phenyl-γ-aminopropyltrimethoxysilane; After the mixture B is cooled to 50°C, 6.5kg of filler, 1kg of antioxidant and 7.5kg of high-flexibility rubber in Preparation Example 1 are added, stirred and mixed for 2h, and then vacuum treated for 24h at a vacuum degree of 5kPa and a temperature of 100°C to obtain PUR for seamless dispensing of underwear; wherein the filler is a mixture of carbon black and talcum powder, and the weight ratio of carbon black to talcum powder is 1:1; the antioxidant is dithiodipropionate.

[0028] Example 3 Example 3 provides a method for preparing PUR for seamless dispensing of underwear, comprising the following steps: First, 20 kg of polycarboxylate and 10 kg of polyether polyol are stirred and mixed uniformly to obtain an oligomeric mixture; wherein the polycarboxylate is polyhydroxyalkanoate; and the polyether polyol is polyoxypropylene glycol; 35 kg of isocyanate, 30 kg of tackifying resin and half of the oligomeric mixture are added into a reaction kettle, stirred and heated to 125° C., maintained for 3 hours, allowed to stand for 24 hours, and then the remaining oligomeric mixture is added, and nitrogen is introduced to raise the temperature to 135° C., stirred for 2 hours, allowed to stand, and when the water content is detected to be less than 500 ppm, a mixture A is obtained; wherein the isocyanate is diphenylmethane diisocyanate; the tackifying resin is an acrylate resin; 35 kg of isocyanate was melted at 130° C., and allowed to stand for 1 hour to cool down to 95° C. to obtain molten isocyanate; wherein the isocyanate was diphenylmethane diisocyanate; After the mixture A is cooled to 70°C, nitrogen is charged into the reactor, molten isocyanate is added and stirred, the temperature is controlled at 100°C, stirred for 3 hours, and then 2kg of catalyst, 2kg of chain extender, and 5kg of cross-linking agent are added, and stirring is continued for 40 minutes to obtain a mixture B; wherein the catalyst is diisobutyl phthalate; the chain extender is sodium 1,2-dihydroxy-3-propanesulfonate; and the cross-linking agent is N-phenyl-γ-aminopropyltrimethoxysilane; After the mixture B is cooled to 50°C, 10kg of filler, 1.5kg of antioxidant and 10kg of high-flexibility rubber in Preparation Example 1 are added, stirred and mixed for 2h, and then vacuum treated for 24h at a vacuum degree of 5kPa and a temperature of 100°C to obtain PUR for seamless dispensing of underwear; wherein the filler is a mixture of carbon black and talcum powder, and the weight ratio of carbon black to talcum powder is 1:1; the antioxidant is dithiodipropionate.

[0029] Example 4 Example 4 provides a method for preparing PUR for seamless dispensing of underwear, comprising the following steps: First, 12.5 kg of polycarboxylate and 7.5 kg of polyether polyol were stirred and mixed uniformly to obtain an oligomeric mixture; wherein the polycarboxylate was polyhydroxyalkanoate; and the polyether polyol was polyoxypropylene glycol; 28 kg of isocyanate, 24 kg of tackifying resin and half of the oligomeric mixture were added into a reaction kettle, stirred and heated to 128° C., maintained for 2.5 hours, allowed to stand for 24 hours, and then the remaining oligomeric mixture was added, and nitrogen was introduced to raise the temperature to 135° C., stirred continuously for 1.5 hours, allowed to stand, and when the water content detected reached less than 500 ppm, a mixture A was obtained; wherein the isocyanate was diphenylmethane diisocyanate; the tackifying resin was acrylate resin; 29.5 kg of isocyanate was melted at 130° C., and allowed to stand for 1 hour to cool down to 100° C. to obtain molten isocyanate; wherein the isocyanate is diphenylmethane diisocyanate; After the mixture A is cooled to 75°C, nitrogen is charged into the reactor, molten isocyanate is added and stirred, the temperature is controlled at 100°C, stirred for 2.5 hours, 1.3 kg of catalyst, 1.5 kg of chain extender, and 3.5 kg of cross-linking agent are added, and stirring is continued for 40 minutes to obtain a mixture B; wherein the catalyst is diisobutyl phthalate; the chain extender is sodium 1,2-dihydroxy-3-propanesulfonate; and the cross-linking agent is N-phenyl-γ-aminopropyltrimethoxysilane; After the mixture B is cooled to 60°C, 6.5kg of filler, 1kg of antioxidant and 7.5kg of high-flexibility rubber in Preparation Example 1 are added, stirred and mixed for 1.5h, and then vacuum treated for 24h at a vacuum degree of 7kPa and a temperature of 110°C to obtain PUR for seamless dispensing of underwear; wherein the filler is a mixture of carbon black and talcum powder, and the weight ratio of carbon black to talcum powder is 1:1; the antioxidant is disodium thiodipropionate.

[0030] Example 5 Example 5 provides a method for preparing PUR for seamless dispensing of underwear, comprising the following steps: First, 12.5 kg of polycarboxylate and 7.5 kg of polyether polyol were stirred and mixed uniformly to obtain an oligomeric mixture; wherein the polycarboxylate was polyhydroxyalkanoate; and the polyether polyol was polyoxypropylene glycol; 28 kg of isocyanate, 24 kg of tackifying resin and half of the oligomeric mixture were added into a reaction kettle, stirred and heated to 130° C., maintained for 2 hours, allowed to stand for 24 hours, and then the remaining oligomeric mixture was added, and nitrogen was introduced and heated to 135° C., stirred for 1 hour, allowed to stand, and when the water content was detected to be less than 500 ppm, a mixture A was obtained; wherein the isocyanate was diphenylmethane diisocyanate; and the tackifying resin was an acrylate resin; 29.5 kg of isocyanate was melted at 130° C., and allowed to stand for 1 hour to cool down to 105° C. to obtain molten isocyanate; wherein the isocyanate was diphenylmethane diisocyanate; After the mixture A is cooled to 80°C, nitrogen is charged into the reactor, molten isocyanate is added and stirred, the temperature is controlled to 100°C, stirred for 2 hours, and then 1.3 kg of catalyst, 1.5 kg of chain extender, and 3.5 kg of cross-linking agent are added, and stirring is continued for 40 minutes to obtain a mixture B; wherein the catalyst is diisobutyl phthalate; the chain extender is sodium 1,2-dihydroxy-3-propanesulfonate; and the cross-linking agent is N-phenyl-γ-aminopropyltrimethoxysilane; After the mixture B is cooled to 70°C, 6.5kg of filler, 1kg of antioxidant and 7.5kg of high-flexibility rubber in Preparation Example 1 are added, stirred and mixed for 1h, and then vacuum treated for 24h at a vacuum degree of 10kPa and a temperature of 120°C to obtain PUR for seamless dispensing of underwear; wherein the filler is a mixture of carbon black and talcum powder, and the weight ratio of carbon black to talcum powder is 1:1; the antioxidant is disodium thiodipropionate.

[0031] Example 6 The difference between Example 6 and Example 4 is that the high-flexibility rubber is the high-flexibility rubber in Preparation Example 2; the remaining steps are consistent with Example 4.

[0032] Example 7 The difference between Example 7 and Example 4 is that the high-flexibility rubber is the high-flexibility rubber in Preparation Example 3; the remaining steps are consistent with Example 4.

[0033] Example 8 The difference between Example 8 and Example 4 is that the high-flexibility rubber is the high-flexibility rubber in Preparation Example 4; the remaining steps are consistent with Example 4.

[0034] Example 9 The difference between Example 9 and Example 6 is that the filler is carbon black; the remaining steps are consistent with Example 6.

[0035] Example 10 The difference between Example 10 and Example 6 is that the filler is talcum powder; the remaining steps are consistent with Example 6.

[0036] Comparative Example Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that after the mixed material B is cooled to 50°C, 3kg of filler and 0.5kg of antioxidant are added, stirred and mixed for 2h, and then vacuum treated for 24h at a vacuum degree of 5kPa and a temperature of 100°C to obtain PUR for seamless dispensing of underwear; the remaining steps are consistent with Example 1.

[0037] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that after the mixture B is cooled to 50°C, 3kg of filler, 0.5kg of antioxidant and 5kg of natural rubber are added, stirred and mixed for 2h, and then vacuum treated for 24h at a vacuum degree of 5kPa and a temperature of 100°C to obtain PUR for seamless dispensing of underwear; the remaining steps are consistent with Example 1.

[0038] Performance test peel strength: PUR was heated at 120℃, then coated on the underwear fabric with a 0.4μm pore size round screen, and then laminated with another piece of underwear fabric. The laminated fabric was then pressed with a press at 60℃ and 1.5kgf / cm 2 The samples were pressed under pressure for 10 seconds, placed in a constant temperature and humidity environment at 18°C ​​and 80% humidity for 48 hours, and their peel strength was tested.

[0039] Shore hardness: PUR is heated at 120℃, then coated on underwear fabric with a 0.4μm pore size round screen, and then laminated with another piece of underwear fabric. The laminated fabric is then pressed with a press at 60℃ and 1.5kgf / cm 2 The fabric was pressed under pressure for 10 seconds and placed in a constant temperature and humidity environment at 18°C ​​and 80% humidity for 48 hours to obtain the test fabric. The Shore hardness was tested using a D-type Shore hardness tester in accordance with GB / T2411-2008 standard. The lower the Shore hardness, the better the softness of the PUR.

[0040] Table 1 PUR test results Combining Example 1, Comparative Example 1 and Comparative Example 2, the PUR in Example 1 has both good softness and good peel strength. It can be seen that the PUR in this application, by adding high-flexibility rubber, can improve its peel strength while also improving its softness.

[0041] In combination with Examples 1-3, the performance of the PUR in Example 2 is the best. It can be seen that when preparing PUR, increasing the amount of raw materials used will increase the performance of the PUR first and then decrease.

[0042] Combining Example 2, Example 4 and Example 5, the performance of PUR in Example 4 is the best, which shows that when preparing PUR, the preparation conditions in Example 4 are the best.

[0043] Combining Example 4, Example 6 and Example 7, the performance of PUR in Example 6 is the best. It can be seen that when preparing high-flexibility rubber, the ratio of natural rubber, plasticizer, tackifier and vulcanizer in Preparation Example 2 is optimal, so that the performance of high-flexibility rubber is the best.

[0044] Combining Example 6 and Example 8, the performance of PUR in Example 6 is better. It can be seen that when preparing high-flexibility rubber, the vulcanizing agent is preferably a mixture of sulfur and tetramethylthiuram disulfide, and the performance of the high-flexibility rubber is the best.

[0045] Combining Example 6, Example 9 and Example 10, the peel strength of PUR in Example 6 is relatively high. It can be seen that when preparing PUR, the filler is preferably a mixture of carbon black and talcum powder. The combination of the two can further improve the peel strength of the obtained PUR.

[0046] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed. However, as long as it is within the scope of the claims of the present application, it shall be protected by the patent law.

Claims

1. A PUR for seamless dispensing of underwear, characterized by: The raw materials of the PUR include the following components in parts by weight: 45-70 parts of isocyanate, 5-20 parts of polycarboxylate, 5-10 parts of polyether polyol, 18-30 parts of tackifying resin, 0.5-2.0 parts of catalyst, 1.0-2.0 parts of chain extender, 2.0-5.0 parts of cross-linking agent, 3-10 parts of filler, 0.5-1.5 parts of antioxidant, and 5-10 parts of high-flexibility rubber; The raw materials of the high-flexibility rubber include: natural rubber, plasticizer, tackifier and vulcanizer.

2. The PUR for seamless dispensing of underwear according to claim 1, characterized in that: The weight ratio of natural rubber, plasticizer, tackifier and vulcanizer in the high-flexibility rubber is 1: (0.2-0.4): (0.1-0.3): (0.08-0.12).

3. The PUR for seamless dispensing of underwear according to claim 2, characterized in that: The preparation method of the high-flexibility rubber comprises the following steps: Adding a plasticizer and a tackifier to natural rubber, and kneading the mixture at 80-120° C. to obtain a mixture; Then, a vulcanizing agent is added to the mixture, and vulcanization is performed at 140-160° C. to obtain a high-flexibility rubber.

4. The PUR for seamless dispensing of underwear according to claim 3, characterized in that: The plasticizer includes dioctyl phthalate.

5. The PUR for seamless dispensing of underwear according to claim 3, characterized in that: The tackifier includes rosin resin.

6. The PUR for seamless dispensing of underwear according to claim 3, characterized in that: The vulcanizing agent comprises a mixture of sulfur and tetramethylthiuram disulfide.

7. The PUR for seamless dispensing of underwear according to claim 1, characterized in that: The filler comprises a mixture of carbon black and talcum powder.

8. A method for preparing PUR for seamless dispensing of underwear according to any one of claims 1 to 7, characterized in that: The following steps are involved: Firstly, polycarboxylate and polyether polyol are stirred and mixed uniformly to obtain an oligomeric mixture; Add part of the isocyanate, the tackifying resin and part of the oligomeric mixture into a reaction kettle, stir and heat to 125-130°C, maintain for 2-3 hours, let stand for 24 hours, then add the remaining oligomeric mixture, introduce nitrogen and heat to 135°C, continue stirring for 1-2 hours, let stand, and wait until the water content is less than 500ppm to obtain a mixture A; The remaining isocyanate is melted at 130°C, and allowed to stand for 1 hour to cool to 95-105°C to obtain molten isocyanate; After the mixture A is cooled to 70-80°C, nitrogen is charged into the reactor, molten isocyanate is added and stirred, the temperature is controlled at about 100°C, stirred for 2-3 hours, and then a catalyst, a chain extender, and a cross-linking agent are added, and stirring is continued for 40 minutes to obtain a mixture B; After the mixture B is cooled to 50-70°C, fillers, antioxidants and high-soft rubber are added, stirred and mixed for 1-2 hours, and then vacuum treated for 24 hours at a vacuum degree of 5kPa-10kPa and a temperature of 100°C-120°C to obtain PUR for seamless dispensing of underwear.

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