Plasticizer corrosion resistant yellow glue and preparation method thereof

Abstract

The invention provides yellow glue resistant to corrosion of a plasticizer and a preparation method of the yellow glue. The yellow glue is prepared from a polyurethane prepolymer, a chloroprene rubber sheet, methyl methacrylate, benzoyl peroxide, an anti-aging agent, butanone, cyclohexane, dimethyl carbonate and tackifying resin. The polyurethane prepolymer is prepared from the following components in parts by weight: 10 to 14 parts of 1, 4-butanediol adipic acid polyester polyol, 4 to 8 parts of polycaprolactone polyol, 1 to 3 parts of diphenylmethane diisocyanate, 0.05 to 0.15 part of 1, 6-hexanediol, 1 to 2 parts of hydroxyethyl methacrylate, 0.01 to 0.03 part of organic bismuth catalyst and 75 to 80 parts of butanone. The polyurethane prepolymer with specific crystallization performance is synthesized through cooperation of polycaprolactone polyol and polyester polyol, and the yellow glue is endowed with excellent plasticizer corrosion resistance and low-temperature activation capacity. Active groups in the polyurethane prepolymer are subjected to graft copolymerization with the chloroprene rubber adhesive and MMA, and a plasticizer-resistant polyurethane chain segment is introduced into a molecular chain of the chloroprene rubber adhesive, so that a hard segment-soft segment alternating block structure is formed, and corrosion resistance and viscoelasticity are both considered.

Description

Technical Field

[0001] This invention relates to the field of PVC adhesive technology, specifically to a yellow adhesive resistant to plasticizer corrosion and its preparation method, which is particularly suitable for room temperature bonding of PVC artificial leather, PVC film and substrates such as EVA and rubber. Background Technology

[0002] PVC (polyvinyl chloride) materials are widely used in footwear, bags, furniture, and automotive interiors due to their affordability, weather resistance, and ease of processing. In these applications, PVC materials often need to be bonded to other substrates (such as EVA, rubber, and fabrics) using adhesives. However, to achieve flexibility, PVC products typically contain 20-50 wt% plasticizers (such as phthalates). These plasticizers gradually migrate and precipitate into the adhesive layer during use, causing swelling and dissolution of traditional neoprene adhesives. This leads to softening of the adhesive film, decreased cohesive strength, and ultimately, rapid loss of adhesion or even complete delamination. Experiments show that PVC products bonded with traditional neoprene adhesive typically experience a drop in peel strength of over 50% after 7 days at 50°C, and essentially lose their adhesiveness after 30 days.

[0003] Polyurethane adhesives, due to the presence of highly polar urethane groups in their molecular structure, exhibit good resistance to plasticizers and are currently the mainstream choice for bonding PVC materials in industry. However, polyurethane adhesives have significant drawbacks: their activation temperature is typically above 50°C, requiring ovens or heating equipment, resulting in high energy consumption and low efficiency. Furthermore, they are difficult to activate by heating large or irregular workpieces, severely limiting production efficiency and application scope.

[0004] To address the aforementioned issues, Chinese patent application CN202110308832.X discloses a yellow rubber resistant to plasticizer migration and its preparation method, using EVM (ethylene-vinyl acetate copolymer) rubber to modify chloroprene rubber. However, the core raw material of this technology, EVM rubber, currently relies heavily on imports, with no stable domestic mass production capacity. Furthermore, the quality of imported raw materials fluctuates significantly between batches, leading to unstable product quality and difficulty in meeting the demands of large-scale industrial production. In addition, the compatibility between EVM rubber and chloroprene rubber is limited; excessive addition can cause colloidal phase separation, affecting adhesive performance. Therefore, there is an urgent need in this field to develop a novel yellow rubber with stable raw material sources, room temperature operation, excellent resistance to plasticizer corrosion, and long-lasting adhesive strength to replace existing import-dependent technologies and meet the pressing needs of the PVC products industry. Summary of the Invention

[0005] This invention addresses the problems of existing yellow adhesives resistant to plasticizer corrosion by providing a yellow adhesive resistant to plasticizer corrosion and its preparation method. It uses domestically produced raw materials and can achieve effective bonding within a wide temperature range of 10-70℃. Moreover, the bonded material can still maintain a level of adhesion even after accelerated aging at 50℃ for 30 days. This fundamentally solves the triple technical problems of existing technologies: neoprene adhesives are not resistant to plasticizer corrosion, polyurethane adhesives require heat activation, and EVM modified raw materials rely on imports.

[0006] The present invention is implemented as follows: a yellow adhesive resistant to plasticizer corrosion, wherein the components are in the following weight parts: 20-40 parts of polyurethane prepolymer, 10-16 parts of chloroprene film, 6-10 parts of methyl methacrylate (MMA), 0.1-0.3 parts of benzoyl peroxide (BPO), 0.1-0.3 parts of antioxidant, 4-8 parts of methyl ethyl ketone (MEK), 15-35 parts of cyclohexane, 6-10 parts of dimethyl carbonate, and 5-12 parts of tackifying resin; wherein the polyurethane prepolymer is in the following weight parts: 10-14 parts of 1,4-butanediol adipate polyester polyol, 4-8 parts of polycaprolactone polyol, 1-3 parts of diphenylmethane diisocyanate (MDI), 0.05-0.15 parts of 1,6-hexanediol, 1-2 parts of hydroxyethyl methacrylate, 0.01-0.03 parts of organic bismuth catalyst, and 75-80 parts of MEK. All raw materials used in this invention are domestically produced industrial-grade commodities. This invention synthesizes a polyurethane prepolymer with specific crystallinity properties through the synergistic use of polycaprolactone polyol and 1,4-butanediol adipate polyester polyol, endowing yellow rubber with excellent resistance to plasticizer corrosion and low-temperature activation ability. By utilizing the active groups in the polyurethane prepolymer to graft copolymerize with chloroprene rubber and MMA, plasticizer-resistant polyurethane segments are introduced into the chloroprene rubber molecular chain, forming a block structure with alternating "hard segment-soft segment" structures, thus balancing corrosion resistance and viscoelasticity.

[0007] Preferably, the tackifying resin is a compound of terpene phenol resin, rosin-modified resin, and phenolic resin. More preferably, the components of the tackifying resin are, by weight, 3-6 parts terpene phenol resin, 1-3 parts rosin-modified resin, and 3-5 parts phenolic resin. The compounding of these three tackifying resins optimizes the bidirectional wetting properties of the yellow glue on PVC and EVA, improving interfacial adhesion strength and processability.

[0008] Preferably, the weight ratio of the 1,4-butanediol adipate polyester polyol to the polycaprolactone polyol is (1.5-3):1. This ratio range allows the yellow gum to maintain excellent resistance to plasticizer corrosion while having the longest tack retention time and the best balance of cohesive strength. More preferably, the weight ratio of the 1,4-butanediol adipate polyester polyol to the polycaprolactone polyol is (2-2.5):1.

[0009] Preferably, the polycaprolactone polyol has a molecular weight of 2000-4000. Polycaprolactone polyols within this molecular weight range can give the synthesized polyurethane prepolymer suitable amorphous properties, ensuring that the yellow glue can be activated and bonded at temperatures above 10°C without heating.

[0010] Preferably, the chloroprene rubber sheet is a chloroprene rubber sheet. This chloroprene rubber sheet has an intrinsic viscosity of 800-1500 cps in a 12wt% toluene solution at 25°C, exhibits rapid crystallization, high cohesive strength, and provides excellent initial adhesion.

[0011] Preferably, the antioxidant is 2,6-di-tert-butyl-p-cresol (BHT). Adding 2,6-di-tert-butyl-p-cresol in the later stages of the polymerization reaction can prevent the decrease in fluidity caused by self-polymerization of the adhesive, while simultaneously improving the aging resistance of the yellow adhesive.

[0012] The preparation method of the above-mentioned plasticizer-resistant yellow glue includes the following steps: Step A: Polyurethane prepolymer synthesis: (1) 1,4-butanediol adipate polyester polyol and polycaprolactone polyol are placed in a vacuum prepolymer reactor and heated to 110-130℃, and vacuum dehydrated for 0.5-1h; (2) The temperature of the vacuum prepolymer reactor is controlled to drop to 85-95℃, 30% of the total amount of butanone is added, and after stirring evenly, an organic bismuth catalyst is added; (3) The temperature of the vacuum prepolymer reactor is controlled at 80-85℃, and dimethyl ethyl ketone is added dropwise. (3) Add phenylmethane diisocyanate and stir continuously for 10-20 min; (4) Add 1,6-hexanediol to the vacuum prepolymer reactor, continue stirring and monitor the current value of the reaction system. When the current reaches 75-85A, it indicates that the molecular weight has increased to the target range; (5) Add 15% of the total amount of butanone and hydroxyethyl methacrylate to the vacuum prepolymer reactor, react at 75-85℃ for 0.5-1.5 h, and after the current stabilizes, cool down to below 50℃, add the remaining butanone, stir evenly and discharge to obtain polyurethane. Ester prepolymer; Step B: Grafting modification: (1) Add butanone and cyclohexane to the reactor according to the formula amount of yellow gum, and add chloroprene rubber sheet while stirring. Control the reactor temperature to 75-85℃ and continue stirring to dissolve for 0.5-1.5h; (2) Add the polyurethane prepolymer and methyl methacrylate obtained in step A, and raise the temperature to 80-85℃; add the initiator benzoyl peroxide, and maintain the reaction at 80-85℃ for 2-4h. When the current value reaches 65-75A, it indicates that the grafting reaction has reached the target degree; (3) ) Cool to 60-70℃, add dimethyl carbonate and antioxidant, stir for 20-40min; Step C: Tackifying resin preparation: (1) Continue to add tackifying resin, stir at high speed for 1-2h until completely dissolved; (2) Take a sample to test the viscosity, ensure that the viscosity is between 4000-5000cps / 25℃. When the viscosity is higher than 5000cps / 25℃, use dimethyl carbonate to adjust the viscosity to 4000-5000cps / 25℃, filter and discharge, and you will get the finished yellow glue resistant to plasticizer corrosion. In the later stage of polyurethane prepolymer synthesis in step A and in the grafting modification process in step B, as the reaction proceeds, the viscosity of the reaction system increases, the resistance increases, and the current will change accordingly. By monitoring the current value of the reaction system through the frequency converter, the molecular weight growth can be reflected in real time, which can realize precise quality control in continuous production and significantly improve the batch stability of the product.

[0013] Compared with the prior art, the present invention has the following significant advantages: (1) Solving import dependence and realizing the localization of raw materials: It adopts domestic raw materials, gets rid of dependence on imported EVM rubber, the raw material supply is stable and the cost is controllable, it is suitable for large-scale industrial production and has important industrial strategic value. (2) Breaking through temperature limitations and realizing room temperature operation: Through the non-crystalline design of polycaprolactone polyol, the activation temperature of yellow glue is reduced to below 10℃, and it can be effectively bonded in a wide temperature range of 10-70℃. No heating equipment is required, saving energy and reducing consumption, and improving production efficiency. (3) Excellent resistance to plasticizer corrosion: After 30 days of accelerated aging at 50℃, it still maintains the adhesion strength at the material breaking level, which solves the problem of degumming after long-term storage of PVC products and extends the service life of products. (4) Strong process controllability: The innovative current monitoring method reflects the molecular weight growth in real time, replacing the traditional offline viscosity test, realizing precise quality control in continuous production, and significantly improving the batch stability of products. (5) Overall performance balance: Through the synergistic optimization of polyol ratio, tackifying resin compounding and solvent system, the best balance is achieved between corrosion resistance, viscosity retention time, cohesive strength and process operability, so as to meet the differentiated needs of different application scenarios. Detailed Implementation

[0014] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0015] Examples 1-3

[0016] A yellow adhesive resistant to plasticizer corrosion, wherein the components are shown in parts by weight as shown in Table 1, and the components of the polyurethane prepolymer are shown in Table 3, wherein the tackifying resin is a compound of terpene phenol resin, rosin-modified resin and phenolic resin, and the components of the tackifying resin are 3 parts by weight of terpene phenol resin, 3 parts of rosin-modified resin and 5 parts of phenolic resin. The chloroprene rubber sheet is a chloroprene rubber sheet. The antioxidant is 2,6-di-tert-butyl-p-cresol (BHT). The preparation method of the above-mentioned yellow adhesive resistant to plasticizer corrosion includes the following steps:

[0017] Step A: Place 1,4-butanediol adipate polyester polyol and polycaprolactone polyol into a vacuum prepolymer reactor and heat to 110°C for vacuum dehydration for 1 hour; (2) Control the vacuum prepolymer reactor to cool down to 95°C, add 30% of the total amount of butanone, stir evenly and then add organic bismuth catalyst; (3) Control the temperature of the vacuum prepolymer reactor at 80°C, add diphenylmethane diisocyanate dropwise and stir continuously for 15 minutes; (4) Add 1,6-hexanediol to the vacuum prepolymer reactor, continue stirring and monitor the current value of the reaction system. When the current reaches 75A, it indicates that the molecular weight has increased to the target range; (5) Add 15% of the total amount of butanone and hydroxyethyl methacrylate to the vacuum prepolymer reactor, react at 80°C for 0.5 hours, and after the current stabilizes, cool down to below 50°C, add the remaining butanone, stir evenly and then discharge to obtain polyurethane prepolymer.

[0018] Step B: Grafting modification: (1) Add methyl ethyl ketone and cyclohexane to the reactor according to the formula amount of yellow gum, and add chloroprene rubber sheet while stirring. Control the temperature of the reactor to 75°C and continue stirring to dissolve for 1.5h; (2) Add the polyurethane prepolymer and methyl methacrylate obtained in step A, and raise the temperature to 85°C; add the initiator benzoyl peroxide, keep the reaction at 85°C for 2h, and when the current value reaches 75A, it indicates that the grafting reaction has reached the target level; (3) Cool down to 60°C, add dimethyl carbonate and antioxidant, and stir for 40min.

[0019] Step C: Tackifying resin preparation: (1) Continue to add tackifying resin and stir at high speed for 2 hours until completely dissolved; (2) Take a sample to test the viscosity. In addition, use dimethyl carbonate to adjust the sample viscosity to 4000cps / 25℃, filter the material, and you will get the yellow glue product that is resistant to plasticizer corrosion.

[0020] Examples 4-6

[0021] A yellow adhesive resistant to plasticizer corrosion, wherein the components are shown in parts by weight as shown in Table 1, and the components of the polyurethane prepolymer are shown in Table 3, wherein the tackifying resin is a compound of terpene phenol resin, rosin-modified resin and phenolic resin, and the components of the tackifying resin are 5 parts by weight of terpene phenol resin, 2 parts of rosin-modified resin and 4 parts of phenolic resin. The weight ratio of 1,4-butanediol adipate polyester polyol to polycaprolactone polyol in the polyurethane prepolymer is 2:1. The chloroprene rubber sheet is a chloroprene rubber sheet. The antioxidant is 2,6-di-tert-butyl-p-cresol (BHT). The preparation method of the above-mentioned yellow adhesive resistant to plasticizer corrosion includes the following steps:

[0022] Step A: Polyurethane prepolymer synthesis: (1) Place 1,4-butanediol adipate polyester polyol and polycaprolactone polyol into a vacuum prepolymer reactor and heat to 130°C, then vacuum dehydrate for 0.5 h; (2) Control the vacuum prepolymer reactor to cool down to 85°C, add 30% of the total amount of butanone, stir evenly, and then add organic bismuth catalyst; (3) Control the temperature of the vacuum prepolymer reactor at 85°C, add diphenylmethane diisocyanate dropwise, and continue stirring for 10 min; (4) Add 1,6-hexanediol to the vacuum prepolymer reactor, continue stirring and monitor the current value of the reaction system. When the current reaches 80A, it indicates that the molecular weight has increased to the target range; (5) Add 15% of the total amount of butanone and hydroxyethyl methacrylate to the vacuum prepolymer reactor, react at 75°C for 1.5 h, and after the current stabilizes, cool down to below 50°C, add the remaining butanone, stir evenly, and then discharge to obtain polyurethane prepolymer.

[0023] Step B: Grafting modification: (1) Add methyl ethyl ketone and cyclohexane to the reactor according to the formula amount of yellow gum, and add chloroprene rubber sheet while stirring. Control the temperature of the reactor to 85°C and continue stirring to dissolve for 0.5h; (2) Add the polyurethane prepolymer and methyl methacrylate obtained in step A, and heat to 80°C; add the initiator benzoyl peroxide, maintain the reaction at 80°C for 4h, and when the current value reaches 70A, it indicates that the grafting reaction has reached the target level; (3) Cool down to 70°C, add dimethyl carbonate and antioxidant, and stir for 20min.

[0024] Step C: Tackifying resin preparation: (1) Continue to add tackifying resin and stir at high speed for 1 hour until completely dissolved; (2) Take a sample to test the viscosity. In addition, use dimethyl carbonate to adjust the sample viscosity to 4500cps / 25℃, filter the material, and you will get the yellow glue product that is resistant to plasticizer corrosion.

[0025] Examples 7-9

[0026] A yellow adhesive resistant to plasticizer corrosion, wherein the components are shown in Table 1 by weight, and the components of the polyurethane prepolymer are shown in Table 3. The tackifying resin is a compound of terpene phenolic resin, rosin-modified resin, and phenolic resin, wherein the components of the tackifying resin are 6 parts by weight of terpene phenolic resin, 1 part of rosin-modified resin, and 5 parts of phenolic resin. The weight ratio of 1,4-butanediol adipate polyester polyol to polycaprolactone polyol in the polyurethane prepolymer is 3:1. The chloroprene rubber sheet is a chloroprene rubber sheet. The antioxidant is 2,6-di-tert-butyl-p-cresol (BHT). The preparation method of the above-mentioned yellow adhesive resistant to plasticizer corrosion includes the following steps:

[0027] Step A: Polyurethane prepolymer synthesis: (1) Place 1,4-butanediol adipate polyester polyol and polycaprolactone polyol into a vacuum prepolymer reactor and heat to 120°C, then vacuum dehydrate for 45 min; (2) Control the vacuum prepolymer reactor to cool down to 90°C, add 30% of the total amount of butanone, stir evenly, and then add organic bismuth catalyst; (3) Control the temperature of the vacuum prepolymer reactor at 83°C, add diphenylmethane diisocyanate dropwise, and continue stirring for 15 min; (4) Add 1,6-hexanediol to the vacuum prepolymer reactor, continue stirring and monitor the current value of the reaction system. When the current reaches 75A, it indicates that the molecular weight has increased to the target range; (5) Add 15% of the total amount of butanone and hydroxyethyl methacrylate to the vacuum prepolymer reactor, react at 80°C for 1 h, and after the current stabilizes, cool down to below 50°C, add the remaining butanone, stir evenly, and then discharge to obtain polyurethane prepolymer.

[0028] Step B: Grafting modification: (1) Add methyl ethyl ketone and cyclohexane to the reactor according to the formula amount of yellow gum, and add chloroprene rubber sheet while stirring. Control the temperature of the reactor to 80°C and continue stirring to dissolve for 1 hour; (2) Add the polyurethane prepolymer and methyl methacrylate obtained in step A, and raise the temperature to 83°C; add the initiator benzoyl peroxide, keep the reaction at 83°C for 3 hours, and when the current value reaches 65A, it indicates that the grafting reaction has reached the target level; (3) Cool down to 60°C, add dimethyl carbonate and antioxidant, and stir for 30 minutes.

[0029] Step C: Tackifying resin preparation: Continue to add tackifying resin and stir at high speed for 1.5 hours until completely dissolved; (2) Take a sample to test the viscosity. In addition, use dimethyl carbonate to adjust the sample viscosity to 4800cps / 25℃, filter the material, and you will get the finished yellow glue that is resistant to plasticizer corrosion.

[0030] Examples 10-12

[0031] A yellow adhesive resistant to plasticizer corrosion, wherein the components are shown in parts by weight as shown in Table 2, and the components of the polyurethane prepolymer are shown in Table 3, wherein the tackifying resin is a compound of terpene phenol resin, rosin-modified resin and phenolic resin, and the components of the tackifying resin are 4 parts by weight of terpene phenol resin, 2 parts of rosin-modified resin and 3 parts of phenolic resin. The weight ratio of 1,4-butanediol adipate polyester polyol to polycaprolactone polyol in the polyurethane prepolymer is 1.5:1. The chloroprene rubber sheet is a chloroprene rubber sheet. The antioxidant is 2,6-di-tert-butyl-p-cresol (BHT). The preparation method of the above-mentioned yellow adhesive resistant to plasticizer corrosion includes the following steps:

[0032] Step A: Polyurethane prepolymer synthesis: (1) Place 1,4-butanediol adipate polyester polyol and polycaprolactone polyol into a vacuum prepolymer reactor and heat to 130°C, then vacuum dehydrate for 1 hour; (2) Control the temperature of the vacuum prepolymer reactor to 90°C, add 30% of the total amount of butanone, stir evenly, and then add organic bismuth catalyst; (3) Control the temperature of the vacuum prepolymer reactor at 85°C, add diphenylmethane diisocyanate dropwise, and continue stirring for 15 minutes; (4) Add 1,6-hexanediol to the vacuum prepolymer reactor, continue stirring and monitor the current value of the reaction system. When the current reaches 80A, it indicates that the molecular weight has increased to the target range; (5) Add 15% of the total amount of butanone and hydroxyethyl methacrylate to the vacuum prepolymer reactor, react at 85°C for 1 hour, and after the current stabilizes, cool down to below 50°C, add the remaining butanone, stir evenly, and then discharge to obtain polyurethane prepolymer.

[0033] Step B: Grafting modification: (1) Add methyl ethyl ketone and cyclohexane to the reactor according to the formula amount of yellow gum, and add chloroprene rubber sheet while stirring. Control the temperature of the reactor to 85°C and continue stirring to dissolve for 1 hour; (2) Add the polyurethane prepolymer and methyl methacrylate obtained in step A, and raise the temperature to 85°C; add the initiator benzoyl peroxide, keep the reaction at 85°C for 2 hours, and when the current value reaches 70A, it indicates that the grafting reaction has reached the target level; (3) Cool down to 65°C, add dimethyl carbonate and antioxidant, and stir for 30 minutes.

[0034] Step C: Tackifying resin preparation: Continue to add tackifying resin and stir at high speed for 1.5 hours until completely dissolved; (2) Take a sample to test the viscosity. In addition, use dimethyl carbonate to adjust the sample viscosity to 4800cps / 25℃, filter the material, and you will get the finished yellow glue that is resistant to plasticizer corrosion.

[0035] Examples 13-17

[0036] A yellow adhesive resistant to plasticizer corrosion, wherein the components are shown in parts by weight as shown in Table 2, and the components of the polyurethane prepolymer are shown in Table 3, wherein the tackifying resin is a compound of terpene phenolic resin, rosin-modified resin and phenolic resin, and the weight ratio of 1,4-butanediol adipate polyester polyol to polycaprolactone polyol in the polyurethane prepolymer is 2:1. The chloroprene rubber sheet is a chloroprene rubber sheet. The antioxidant is 2,6-di-tert-butyl-p-cresol (BHT). In Examples 13-15 and 17, the components of the tackifying resin are 3 parts by weight of terpene phenolic resin, 2 parts by weight of rosin-modified resin and 5 parts by weight of phenolic resin. In Example 16, the components of the tackifying resin are 4 parts by weight of terpene phenolic resin, 2 parts by weight of rosin-modified resin and 4 parts by weight of phenolic resin. The preparation method of the above-mentioned yellow adhesive resistant to plasticizer corrosion includes the following steps:

[0037] Step A: Polyurethane prepolymer synthesis: (1) Place 1,4-butanediol adipate polyester polyol and polycaprolactone polyol into a vacuum prepolymer reactor and heat to 130°C, then vacuum dehydrate for 0.5 h; (2) Control the vacuum prepolymer reactor to cool down to 85°C, add 30% of the total amount of butanone, stir evenly, and then add organic bismuth catalyst; (3) Control the temperature of the vacuum prepolymer reactor at 85°C, add diphenylmethane diisocyanate dropwise, and continue stirring for 10 min; (4) Add 1,6-hexanediol to the vacuum prepolymer reactor, continue stirring and monitor the current value of the reaction system. When the current reaches 80A, it indicates that the molecular weight has increased to the target range; (5) Add 15% of the total amount of butanone and hydroxyethyl methacrylate to the vacuum prepolymer reactor, react at 75°C for 1.5 h, and after the current stabilizes, cool down to below 50°C, add the remaining butanone, stir evenly, and then discharge to obtain polyurethane prepolymer.

[0038] Step B: Grafting modification: (1) Add methyl ethyl ketone and cyclohexane to the reactor according to the formula amount of yellow gum, and add chloroprene rubber sheet while stirring. Control the temperature of the reactor to 85°C and continue stirring to dissolve for 0.5h; (2) Add the polyurethane prepolymer and methyl methacrylate obtained in step A, and heat to 80°C; add the initiator benzoyl peroxide, maintain the reaction at 80°C for 4h, and when the current value reaches 70A, it indicates that the grafting reaction has reached the target level; (3) Cool down to 70°C, add dimethyl carbonate and antioxidant, and stir for 25min.

[0039] Step C: Tackifying resin preparation: Continue to add tackifying resin and stir at high speed for 1.5 hours until completely dissolved; (2) Take a sample to test the viscosity. In addition, use dimethyl carbonate to adjust the sample viscosity to 4500cps / 25℃, filter the material, and you will get the yellow glue product that is resistant to plasticizer corrosion.

[0040] Examples 18-20

[0041] A yellow adhesive resistant to plasticizer corrosion, wherein the components are shown in parts by weight as shown in Table 2, and the components of the polyurethane prepolymer are shown in Table 3, wherein the tackifying resin is a compound of terpene phenolic resin, rosin-modified resin and phenolic resin, and the weight ratio of 1,4-butanediol adipate polyester polyol to polycaprolactone polyol in the polyurethane prepolymer is 2.5:1. The chloroprene rubber sheet is a chloroprene rubber sheet. The antioxidant is 2,6-di-tert-butyl-p-cresol (BHT). In Examples 18 and 20, the components of the tackifying resin are 3 parts by weight of terpene phenolic resin, 2 parts by weight of rosin-modified resin and 5 parts by weight of phenolic resin; in Example 19, the components of the tackifying resin are 6 parts by weight of terpene phenolic resin, 1 part by weight of rosin-modified resin and 5 parts by weight of phenolic resin. The preparation method of the above-mentioned yellow adhesive resistant to plasticizer corrosion includes the following steps:

[0042] Step A: Polyurethane prepolymer synthesis: (1) Place 1,4-butanediol adipate polyester polyol and polycaprolactone polyol into a vacuum prepolymer reactor and heat to 120°C, then vacuum dehydrate for 1 hour; (2) Control the temperature of the vacuum prepolymer reactor to 90°C, add 30% of the total amount of butanone, stir evenly, and then add organic bismuth catalyst; (3) Control the temperature of the vacuum prepolymer reactor at 80°C, add diphenylmethane diisocyanate dropwise, and continue stirring for 20 minutes; (4) Add 1,6-hexanediol to the vacuum prepolymer reactor, continue stirring and monitor the current value of the reaction system. When the current reaches 85A, it indicates that the molecular weight has increased to the target range; (5) Add 15% of the total amount of butanone and hydroxyethyl methacrylate to the vacuum prepolymer reactor, react at 80°C for 1 hour, and after the current stabilizes, cool down to below 50°C, add the remaining butanone, stir evenly, and then discharge to obtain polyurethane prepolymer.

[0043] Step B: Grafting modification: (1) Add methyl ethyl ketone and cyclohexane to the reactor according to the formula amount of yellow gum, and add chloroprene rubber sheet while stirring. Control the temperature of the reactor to 85°C and continue stirring to dissolve for 1 hour; (2) Add the polyurethane prepolymer and methyl methacrylate obtained in step A, and raise the temperature to 85°C; add the initiator benzoyl peroxide, keep the reaction at 85°C for 2 hours, and when the current value reaches 70A, it indicates that the grafting reaction has reached the target level; (3) Cool down to 65°C, add dimethyl carbonate and antioxidant, and stir for 30 minutes.

[0044] Step C: Tackifying resin preparation: Continue to add tackifying resin and stir at high speed for 1.5 hours until completely dissolved; (2) Take a sample to test the viscosity. In addition, use dimethyl carbonate to adjust the sample viscosity to 5000cps / 25℃, filter the material, and you will get the yellow glue product that is resistant to plasticizer corrosion.

[0045] Another comparative example was set up. Comparative example 1 used commercially available yellow glue 285A, with the following formula: 19% chloroprene film, 8% MMA, 10% mixed tackifying resin, 0.01% BPO, 0.02% BHT, 30% methyl ethyl ketone, 25% cyclohexane, and 8% dimethyl carbonate. It does not contain polyurethane prepolymer.

[0046] Comparative Example 2 uses pure polyurethane adhesive, commercially available polyurethane adhesive with a solid content of 25%, which needs to be heated to 60°C to activate bonding.

[0047] Comparative Example 3 uses imported EVM rubber to replace the polyurethane prepolymer of the present invention, and the rest of the formulation is the same as in Example 14.

[0048] Comparative Example 4 is a single polyol polyurethane prepolymer, using only 18 parts of 1,4-butanediol adipate polyester polyol (PBA-3000) and not polycaprolactone polyol (PCL). After preparing the prepolymer, yellow gum was prepared according to the formulation of Example 14.

[0049] Comparative Example 5 uses low molecular weight polycaprolactone, with polycaprolactone polyol (PCL) (molecular weight 1000) used instead of PCL-3000, and the rest is the same as in Example 14.

[0050] Comparative Example 6 uses high molecular weight polycaprolactone, with polycaprolactone polyol (PCL)-5000 (molecular weight 5000) used instead of PCL-3000, and the rest is the same as in Example 14.

[0051] Comparative Example 7 is a process without current monitoring. In step A (4), the current is not monitored and the reaction time is fixed at 2 hours. The rest is the same as in Example 14.

[0052] Table 1. Components and weight parts of yellow gum in Comparative Example 1 and Examples 1-9

[0053] Components Comparative Example 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 polyurethane prepolymer 0 20 30 40 20 30 40 20 30 40 Neoprene film 19 14 13 11 14 13 11 14 13 11 Methyl methacrylate (MMA) 8 8 8 8 8 8 8 10 10 10 Benzoyl peroxide (BPO) 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.2 0.2 0.2 Anti-aging agents 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.1 0.1 0.1 Tackifying resin 10 10 10 10 5 5 5 8 8 8 Butanone 30 4 6 8 4 6 8 4 6 8 Cyclohexane 25 25 20 23 15 20 23 25 35 23 dimethyl carbonate 8 8 8 8 8 8 8 6 6 6

[0054] Table 2. Components and weight parts of yellow gum from Examples 10-20

[0055] Components Example 10 Example 11 Example 12 Example 13 Example 14 Example 15 Example 16 Example 17 Example 18 Example 19 Example 20 polyurethane prepolymer 20 30 40 20 30 40 30 30 30 30 30 Neoprene film 16 16 10 14 13 11 13 13 13 13 13 Methyl methacrylate (MMA) 6 6 6 8 8 8 8 8 8 8 8 Benzoyl peroxide (BPO) 0.3 0.3 0.3 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Anti-aging agents 0.3 0.3 0.3 0.2 0.2 0.2 0.2 0.2 0.2 0.3 0.2 Tackifying resin 12 12 12 10 10 10 10 10 10 12 10 Butanone 4 6 8 4 6 4 6 6 6 6 8 Cyclohexane 25 25 23 25 25 23 25 24 25 25 35 dimethyl carbonate 10 10 10 8 8 8 8 8 8 8 6

[0056] Table 3. Composition of prepolymers in Examples 1-20

[0057] Prepolymer raw material name Examples 1-3 Examples 4-6 Examples 7-9 Examples 10-12 Examples 13-17 Examples 18-20 1,4-Butanediol, Adipate, Polyester Polyol 3000 (Molecular Weight) 14 12 12 12 12.5 10 Polycaprolactone polyol 4 (Molecular weight 3000) 6 (Molecular weight 3000) 4 (Molecular weight 2000) 6 (Molecular weight 4000) 5 (Molecular weight 3000) 8 (Molecular weight 3000) Butanone 78 75 77 80 76 75 Diphenylmethane diisocyanate (MDI) 1 2.2 2.2 3 2 2.2 Organic bismuth catalysts 0.02 0.02 0.01 0.03 0.03 0.02 1,6-Hexanediol 0.1 0.1 0.05 0.15 0.1 0.1 Hydroxyethyl methacrylate 1.3 1.3 1.0 2.0 1.5 1.3

[0058] The adhesive retention times of Examples 1-12 and Comparative Example 1 are shown in Table 4. The adhesive retention time test involved uniformly applying adhesive to PVC leather (2.5 cm wide), placing it at a set temperature (10℃ / 20℃ / 30℃) and 50±2% humidity, and then bonding it to EVA material at 5 / 10 / 20 / 30 / 60 / 120 / 240 min, applying pressure of 0.5 MPa for 10 seconds, and evaluating the bonding effect. The longest "adhesive" placement time was defined as the adhesive retention time. For example, at 20℃, if the material was adhesive after 10 min but not after 20 min, the adhesive retention time was determined to be 10 min at 20℃. The longer the adhesive retention time, the longer the workable time for the worker.

[0059] Table 4. Viscosity maintenance time, in minutes

[0060] serial number Comparative Example 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Example 11 Example 12 10℃ 10 20 20 20 20 30 20 30 30 30 30 30 30 20℃ 20 30 30 30 60 60 30 60 60 60 60 120 60 30℃ 30 30 30 40 60 120 60 120 240 120 120 240 120

[0061] The proportions of polyurethane prepolymer and polycaprolactone polyol both affect the plasticizer corrosion resistance and tack retention time of yellow glue. As can be seen from Table 4, by optimizing the proportions of each component, the yellow glue prepared by this invention has reached or exceeded the tack retention time of Comparative Example 1.

[0062] The plasticizer corrosion resistance of Examples 1-12 and Comparative Example 1 is shown in Table 5. The sample preparation for the plasticizer corrosion resistance test method was as follows: PVC leather (2.5cm wide) was coated with adhesive on both sides of EVA, opened at 25±0.5℃ and 50±2% humidity for 10 minutes, then pressurized at 0.5MPa for 30 seconds after application, and cured at 25±0.5℃ for the corresponding number of days (24 hours is one day). Test conditions: 1h: After application, pressurize at 0.5MPa for 30 seconds, and immediately test the peel strength (N / 2.5cm) after 1 hour, i.e., 0 days of curing. 1D / 3D / 7D / 15D / 30D: After aging in a 50℃ oven for the corresponding number of days, test at 25±0.5℃ for 1 hour. Judgment criteria: OK = material breakage (substrate damaged, adhesive layer not broken), value = measured peel strength.

[0063] Table 5 Resistance to Plasticizer Corrosion

[0064] serial number Comparative Example 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Example 11 Example 12 1h OK OK OK OK OK OK OK OK OK OK OK OK OK 1D OK OK OK OK OK OK OK OK OK OK OK OK OK 3D OK OK OK OK OK OK OK OK OK OK OK OK OK 7D 25 OK OK OK OK OK OK OK OK OK OK OK OK 15D 10 30 OK OK 28 OK OK 25 OK 39 23 32 22 30D 8 25 OK OK 25 OK OK 24 OK 37 22 30 20

[0065] Based on the experimental data in Table 5, Comparative Example 1 showed a significant decrease in peel strength after 7 days, indicating that as time progressed, the plasticizer in the PVC material began to precipitate and corrode the adhesive film, leading to a rapid decline in peel strength, with very weak adhesion after 30 days. In contrast, the yellow adhesive obtained in Examples 2-3, 5-6, and 8 still achieved material breakage after 30 days at 50°C, and the peel strength performance of the other examples was far superior to that of the yellow adhesive in Comparative Example 1. This invention incorporates polyurethane prepolymer-modified neoprene adhesive. Because a polyurethane structure is introduced into the molecular structure, the polyurethane itself is not corroded by plasticizers, and the newly polymerized adhesive also possesses resistance to plasticizer corrosion.

[0066] Table 6 shows the comprehensive performance comparison of Examples 13-20 and Comparative Examples 1-7, where low temperature adhesion refers to the initial peel strength at 5℃ and 10℃. (2) Stability of raw material source: the product performance CV value (coefficient of variation) of three batches of raw materials was tracked.

[0067] Table 6. Comparison of overall performance of Examples 13-20 and Comparative Examples 1-7

[0068] serial number Resistance to plasticizer corrosion (30D) Viscosity retention time (20℃) Low-temperature adhesion (10℃) Source of raw materials Overall score Comparative Example 1 20N (Degumming) 30min Non-stick Domestic ★★☆☆☆ Comparative Example 2 OK (material broken) Heating required Heating required Domestic ★★★☆☆ Comparative Example 3 OK (material broken) 45min Adhesive import dependence ★★★★☆ Comparative Example 4 28N (Degumming) 15min Adhesive Domestic ★★☆☆☆ Comparative Example 5 OK (material broken) 10min Adhesive Domestic ★★★☆☆ Comparative Example 6 OK (material broken) 60min Non-stick Domestic ★★★☆☆ Comparative Example 7 OK (material broken) 50min Adhesive Domestic ★★★☆☆ Example 13 OK (material broken) 60min Adhesive Domestic ★★★★★ Example 14 OK (material broken) 60min Adhesive Domestic ★★★★★ Example 15 OK (material broken) 90min Adhesive Domestic ★★★★★ Example 16 OK (material broken) 60min Adhesive at 5℃ Domestic ★★★★★ Example 17 OK (material broken) 120min Adhesive Domestic ★★★★★ Example 18 OK (material broken) 50min Adhesive at 5℃ Domestic ★★★★★ Example 19 OK (material broken) 60min Adhesive Domestic ★★★★★ Example 20 OK (material broken) 30min Adhesive Domestic ★★★★☆

[0069] As can be seen from the experimental data in Table 6, in Example 18, by optimizing the ratio of synergistic components, the yellow glue could still bond normally at 5°C when PBA:PCL=10:8, making it suitable for winter construction. Furthermore, in Example 15, by fine-tuning the amount of tackifying resin and the proportion of solvent, the tack retention time was extended to 90 minutes. In Example 16, by changing the ratio of tackifying resin, the initial peel strength of the yellow glue to EVA increased by 15%, and the optimized PBA:PCL ratio also had a synergistic effect on low-temperature performance. By optimizing the component ratios, Examples 14 and 17 achieved the best balance between open time and tack retention time. Example 17, by fine-tuning the proportion of MMA and solvent, achieved the best balance between monomer dosage and process performance. In Example 19, by increasing the amount of terpene phenol resin and antioxidant BHT, the yellow glue maintained its material breakage effect under aging tests at 70°C, making it suitable for high-temperature environments such as automotive interiors. Example 20 accelerates solvent evaporation by adjusting the component ratio, shortening the open time to 5-15 minutes, making it suitable for rapid lamination on production lines.

[0070] Comparative Example 1 (traditional chloroprene rubber) completely delaminated after 30 days of aging, proving that unmodified chloroprene rubber cannot solve the problem of plasticizer corrosion. Comparative Example 4 (single polyester polyol) showed some improvement, but still delaminated after 30 days, proving that a blend of PBA and PCL is necessary to balance corrosion resistance and tack maintenance. Comparative Examples 5-6 demonstrated that the molecular weight of PCL must be controlled within the range of 2000-4000; too low a molecular weight results in short tack maintenance time, while too high a molecular weight leads to poor low-temperature activity. This invention achieves technical effects that existing technologies cannot reach through a specific ratio of blended polyols.

[0071] Example 14 maintained the material breaking effect after aging at 50°C for 30 days, while Comparative Example 3 (EVM technology) could also achieve material breaking. However, the raw materials of this invention are 100% domestically produced, and the batch-to-batch performance CV value is <5%, which is significantly better than the CV value of imported EVM of 15-20%, thus solving the key bottleneck of large-scale production.

[0072] By tracking the product performance CV values ​​(coefficient of variation) of three batches of raw materials, it can be seen that the peel strength CV value between batches of Comparative Example 7 (without current monitoring) reached 12%, while the CV value of Example 14 (current monitoring) was <5%, proving the key role of the current monitoring method in product quality stability.

[0073] In summary, this invention can solve the import dependence, get rid of the dependence on imported EVM rubber, and use domestic raw materials. The raw material supply is stable and the cost is controllable. It is suitable for large-scale industrial production and has important industrial strategic value. In terms of technical effects: (1) Breaking the temperature limit and realizing room temperature operation: Through the non-crystalline design of polycaprolactone polyol, the activation temperature of yellow glue is reduced to below 10℃. It can effectively bond in a wide temperature range of 10-70℃ without heating equipment, saving energy and reducing consumption, and improving production efficiency. (2) Excellent resistance to plasticizer corrosion: After 30 days of accelerated aging at 50℃, it still maintains the adhesion strength at the material breaking level, which solves the problem of degumming after long-term storage of PVC products and extends the service life of products. (3) Strong process controllability: The innovative current monitoring method reflects the molecular weight growth in real time, replacing the traditional offline viscosity test, realizing precise quality control in continuous production, and significantly improving the batch stability of products. (4) Overall performance balance: Through the synergistic optimization of polyol ratio, tackifying resin compounding and solvent system, the best balance is achieved between corrosion resistance, viscosity retention time, cohesive strength and process operability, so as to meet the differentiated needs of different application scenarios.

Claims

1. A yellow adhesive resistant to plasticizer corrosion, characterized in that, The components, by weight, are as follows: 20-40 parts polyurethane prepolymer, 10-16 parts chloroprene film, 6-10 parts methyl methacrylate, 0.1-0.3 parts benzoyl peroxide, 0.1-0.3 parts antioxidant, 4-8 parts methyl ethyl ketone, 15-35 parts cyclohexane, 6-10 parts dimethyl carbonate, and 5-12 parts tackifying resin; the polyurethane prepolymer, by weight, comprises the following components: 10-14 parts 1,4-butanediol adipate polyester polyol, 4-8 parts polycaprolactone polyol, 1-3 parts diphenylmethane diisocyanate, 0.05-0.15 parts 1,6-hexanediol, 1-2 parts hydroxyethyl methacrylate, 0.01-0.03 parts organic bismuth catalyst, and 75-80 parts methyl ethyl ketone.

2. The yellow glue resistant to plasticizer corrosion according to claim 1, characterized in that, The tackifying resin is a compound of terpene phenol resin, rosin-modified resin and phenolic resin.

3. The yellow glue resistant to plasticizer corrosion according to claim 1, characterized in that, The tackifying resin comprises, by weight, 3-6 parts of terpene phenol resin, 1-3 parts of rosin-modified resin, and 3-5 parts of phenolic resin.

4. The yellow glue resistant to plasticizer corrosion according to claim 1, characterized in that, The weight ratio of 1,4-butanediol adipate polyester polyol to polycaprolactone polyol in the polyurethane prepolymer is (1.5-3):

1.

5. The yellow adhesive resistant to plasticizer corrosion according to claim 1, characterized in that, The molecular weight of the polycaprolactone polyol is 2000-4000.

6. The yellow glue resistant to plasticizer corrosion according to claim 1, characterized in that, The chloroprene sheet is a chloroprene rubber sheet.

7. The yellow adhesive resistant to plasticizer corrosion according to claim 1, characterized in that, The antioxidant is 2,6-di-tert-butyl-p-cresol.

8. A method for preparing a plasticizer-resistant yellow gum as described in any one of claims 1-7, characterized in that, The steps include: Step A: Polyurethane prepolymer synthesis: (1) Place 1,4-butanediol adipate polyester polyol and polycaprolactone polyol into a vacuum prepolymer reactor and heat to 110-130℃, then vacuum dehydrate for 0.5-1h; (2) Control the temperature of the vacuum prepolymer reactor to 85-95℃, add 30% of the total amount of butanone, stir evenly, and then add organic bismuth catalyst; (3) Control the temperature of the vacuum prepolymer reactor at 80-85℃, add diphenylmethane diisocyanate dropwise, and continue to add... Stir for 10-20 min; (4) Add 1,6-hexanediol to the vacuum prepolymer reactor, continue stirring and monitor the current value of the reaction system. When the current reaches 75-85A, it indicates that the molecular weight has increased to the target range; (5) Add 15% of the total amount of butanone and hydroxyethyl methacrylate to the vacuum prepolymer reactor, react at 75-85℃ for 0.5-1.5 h, and after the current stabilizes, cool down to below 50℃, add the remaining butanone, stir evenly and discharge to obtain polyurethane prepolymer; Step B Grafting modification: (1) Add methyl ethyl ketone and cyclohexane to the reaction vessel according to the formula amount of yellow gum, and add chloroprene rubber sheet while stirring. Control the temperature of the reaction vessel to 75-85℃ and continue stirring to dissolve for 0.5-1.5h; (2) Add the polyurethane prepolymer and methyl methacrylate obtained in step A, and raise the temperature to 80-85℃; add the initiator benzoyl peroxide, and maintain the reaction at 80-85℃ for 2-4h. When the current value reaches 65-75A, it indicates that the grafting reaction has reached the target degree; (3) Cool down to At 60-70℃, add dimethyl carbonate and antioxidant, and stir for 20-40 minutes; Step C: Tackifying resin preparation: (1) Continue to add tackifying resin and stir at high speed for 1-2 hours until completely dissolved; (2) Take a sample to test the viscosity and ensure that the viscosity is between 4000-5000 cps / 25℃. When the viscosity is higher than 5000 cps / 25℃, use dimethyl carbonate to adjust the viscosity to 4000-5000 cps / 25℃. Filter the material to obtain the finished yellow glue resistant to plasticizer corrosion.