Reactive polyurethane hot melt adhesive for laminating and compounding PVC (Polyvinyl Chloride) film and preparation method of reactive polyurethane hot melt adhesive

Abstract

The invention discloses a reactive polyurethane hot melt adhesive for laminating and compounding a PVC (Polyvinyl Chloride) film and a preparation method of the reactive polyurethane hot melt adhesive, so that a product prepared by the invention is very suitable for laminating and compounding a soft PVC film rich in a plasticizer. According to the invention, by designing specific raw materials and proportions, especially polyester polyol with a specific glass transition temperature, and selection and compounding design of a catalyst A and a catalyst B, the polyurethane hot melt adhesive system prepared by the invention can effectively improve the reaction rate in the actual use curing process, a compact structure can be formed more quickly, and the service life of the polyurethane hot melt adhesive system is prolonged. And the bonding strength is not influenced by migration of the plasticizer. Meanwhile, the preparation method provided by the invention is simple, easy to control, good in condition culture and suitable for large-scale industrial production.

Description

Technical Field

[0001] The invention relates to a reactive polyurethane hot melt adhesive and a preparation method thereof, in particular to a reactive polyurethane hot melt adhesive suitable for laminating and compounding soft PVC films and a preparation method thereof, belonging to the technical field of single-component moisture-curing polyurethane hot melt adhesives. Background Art

[0002] Hot melt polyurethane reactive adhesive (hereinafter referred to as HMPUR) is usually composed of a polyurethane prepolymer with an isocyanate terminal group. This adhesive is generally prepared by reacting a polyol with an excess of isocyanate. It is usually solid at room temperature and softens into a liquid when heated. After application, it can be quickly cooled to form a high initial bonding strength, and then the isocyanate reacts with the moisture in the environment or substrate to form the final bonding strength. Due to the diversity of HMPUR raw materials, different types of substrates can be bonded, such as metals, plastics, glass, and ceramics. Among them, soft PVC film materials are also common bonding substrates, which can be used in P4 grade protective clothing and packaging and other fields. At present, plasticizers are often used in industry to achieve the effect of soft films, but because plasticizers will migrate to the adhesive layer over time, the overall bonding strength decreases, affecting the application effect in the field.

[0003] Chinese patent CN109777336B discloses a reactive polyurethane hot melt adhesive for PVC and a preparation method thereof, which mainly uses low-hydroxyl value crystalline polyester polyol as the main raw material to prepare HMPUR. The product has good shear strength for hard PVC (such as sheets and plates), but does not mention the bonding ability and attenuation for soft PVC substrates. After multiple tests and verifications, the applicant found that the bonding effect on soft PVC film is poor, which is mainly manifested in the low final peel strength, which is generally less than 35N / 25mm. The laminated PVC film can be easily torn off, which does not meet the application requirements.

[0004] Therefore, how to provide a reactive polyurethane hot melt adhesive suitable for laminating soft PVC films has become a problem to be solved. Summary of the invention

[0005] The purpose of the present invention is to solve the above technical problems and provide a reactive polyurethane hot melt adhesive and a preparation method thereof, so that the product prepared by the present invention has both high initial bonding strength and high final bonding strength when applied to the field of soft PVC film lamination.

[0006] The technical solution adopted by the present invention is a reactive polyurethane hot melt adhesive for PVC film lamination, and its raw material composition, calculated by mass percentage, is specifically: 10-30 parts of polyether polyol; 10-20 parts of amorphous polyester polyol; 10-20 parts of liquid polyester polyol; 0-20 parts of tackifying resin; Thermoplastic resin 0-20 parts; Isocyanate 20-30 parts; Stabilizer 0.01-0.1 parts; Antioxidant 0.1-0.5 parts; Catalyst A 0.1-0.3 part; Catalyst B 0.05-0.1 part; Adhesion promoter 0.3-0.8 parts.

[0007] In the present invention, polyether polyol, amorphous polyester polyol, liquid polyester polyol, tackifying resin, thermoplastic resin and isocyanate constitute the main materials of the system; stabilizer, antioxidant, catalyst A, catalyst B and adhesion promoter constitute the auxiliary materials of the system.

[0008] The polyether polyol is selected from one of polyoxypropylene glycol, polyoxyethylene glycol, polyoxypropylene-ethylene glycol, polyoxypropylene triol, or polytetramethylene ether glycol, and has a number average molecular weight of 400-8000, preferably 1000-5000; The above-mentioned amorphous polyester polyol is an aromatic polyester polyol. Specifically, the polyacid of the amorphous polyester polyol is selected from at least one of terephthalic acid, phthalic anhydride and isophthalic acid, and the polyol is one or more of ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 2-methyl-1,3-propanediol, 1,4-cyclohexanediol, neopentyl glycol, and 3-methyl-1,5-pentanediol; and the glass transition temperature of the amorphous polyester polyol is greater than 20°C, and the hydroxyl value thereof is 18KOH / mg-56KOH / mg; The liquid polyester polyol is an aromatic polyester polyol or an aliphatic polyester polyol. Specifically, the polyacid of the liquid polyester polyol is selected from at least one of terephthalic acid, phthalic anhydride, isophthalic acid, adipic acid, and sebacic acid, and the polyol is one or more of 1,4-butanediol, 1,6-hexanediol, 2-methyl-1,3-propanediol, 1,4-cyclohexanediol, neopentyl glycol, and 3-methyl-1,5-pentanediol; and the glass transition temperature of the liquid polyester polyol is less than -30°C, and the hydroxyl value is 18KOH / mg-56KOH / mg; The tackifying resin is selected from one or more of acrylic resin, petroleum resin, rosin resin, terpene resin, poly-α-methylstyrene resin, and indene-coumarone resin, and is used to adjust the viscosity of the system; The thermoplastic resin is selected from one or more of ethylene vinyl acetate, polyurethane elastomer, high molecular weight polyester resin, and polyolefin resin to adjust the strength of the system; The above isocyanate is one of diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, isophorone diisocyanate toluene diisocyanate, hexamethylene diisocyanate, and dicyclohexylmethane diisocyanate; The stabilizer is one of phosphoric acid, polyphosphoric acid, p-toluenesulfonyl isocyanate, sebacic acid, benzoyl chloride, and azelaic acid; The antioxidant is one of antioxidant 1010, antioxidant 168, antioxidant 1035, antioxidant 1076, antioxidant 1135, antioxidant 5057 and triphenyl phosphite; The adhesion promoter is one of γ-aminopropyl triethoxysilane, γ-glycidyloxypropyl trimethoxysilane, benzylaminomethyl triethoxysilane, benzylaminopropyl trimethoxysilane, γ-methacryloxypropyl trimethoxysilane, γ-mercaptopropyl triethoxysilane, and γ-mercaptopropyl trimethoxysilane; The catalyst A is one of dibutyltin dilaurate, stannous octoate, tetrabutyl titanate, triethylenediamine, 1,4-dimethylpiperazine, bismorpholinyl diethyl ether, bismorpholinyl triethyl ether, and dimorpholine polyoxyethylene ether; The catalyst B is one of pentamethyldiethylenetriamine, pentamethyldipropylenetriamine, 2,4,6-tris(dimethylaminomethyl)phenol and 1,3,5-tris(dimethylaminopropyl)hexahydrotriazine; The mass ratio of the above catalyst A to catalyst B is 2:1-5:1, preferably 3:1.

[0009] The present invention also provides a method for preparing the above-mentioned reactive polyurethane hot melt adhesive for PVC film lamination, the specific steps of which are: (1) According to the preset ratio, the stabilizer, antioxidant and tackifying resin are added into a vacuum reactor, the temperature is raised to 140°C, and the mixture is stirred and melted; (2) Add polyether polyol, amorphous polyester polyol and liquid polyester polyol, stir and melt, and dehydrate for 1h-2h under vacuum ≤-0.098MPa; (3) Cool down to 100°C, add isocyanate, mix and stir evenly, then heat up to 120°C and react for 1 hour; (4) Adding catalyst A, catalyst B and adhesion promoter, and performing vacuum degassing reaction for 0.5h-1h; (5) After unloading, sealing and packaging, it is ready.

[0010] In the above step (2), the water content after dehydration is ≤500ppm.

[0011] The innovation and beneficial effects of the present invention are: according to the application requirements of soft PVC film, specific raw materials and proportions are designed, especially the selection and proportion of polyester polyol in the main material, the selection and compounding design of catalyst A and catalyst B in the auxiliary material, so that the polyurethane hot melt adhesive system prepared by the present invention can effectively improve the reaction rate in the actual use and curing process of soft PVC film lamination and compounding, form a dense structure faster, will not be affected by the migration of plasticizer, and has both high initial adhesion effect and excellent final adhesion effect. At the same time, the preparation method provided by the present invention is simple, easy to control, mild conditions, and suitable for large-scale industrial production. DETAILED DESCRIPTION

[0012] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0013] Meanwhile, in each embodiment of the present invention, there is no special restriction on the source of each material, and commercially available products known to those skilled in the art and meeting the relevant property requirements may be used. Example 1

[0014] A reactive polyurethane hot melt adhesive for PVC film lamination and compounding, the raw material composition of which, by weight, is shown in the following Table 1.

[0015] raw material Mass fraction Polyether polyol (hydroxyl value 37 KOH / mg) 20 Amorphous polyester polyol (hydroxyl value 56 KOH / mg, Tg 38℃) 19 Liquid polyester polyol (DYNACOLL 7250, hydroxyl value 18-24 KOH / mg) 20 Isocyanate MDI 21 Acrylic resin BR116 (Tg is 60℃) 20 Adhesion promoter (Silquest Y9669) 0.5 Stabilizer (phosphoric acid) 0.05 Antioxidant (1010) 0.5 Catalyst A (bismorpholinyl diethyl ether) 0.2 Catalyst B (pentamethyldipropylenetriamine) 0.05 Table 1: Composition of raw materials used in Example 1.

[0016] When preparing the reactive polyurethane hot melt adhesive for PVC film lamination and compounding, first add a stabilizer, an antioxidant, and a tackifying resin into a vacuum reactor, heat it to 140°C, stir and melt; then add polyether polyol, amorphous polyester polyol, and liquid polyester polyol, stir and melt, and dehydrate for 1h-2h under vacuum conditions of ≤-0.098MPa until the water content is ≤500ppm; cool the system to 100°C, then add isocyanate and stir and mix evenly, then heat it to 120°C and react for 1h; then add catalyst A, catalyst B and adhesion promoter, and perform vacuum degassing reaction for 0.5h-1h until the viscosity and NCO% reach the preset targets; the product is obtained after discharging, sealing and packaging.

[0017] Comparative Example 1 Compared with Example 1, except that Catalyst B is not involved, other raw material compositions and preparation steps are exactly the same.

[0018] Example 2 Compared with Example 1, the difference lies in the raw material composition and ratio design, and the preparation steps are the same.

[0019] raw material Mass fraction Polyether polyol (hydroxyl value 56 KOH / mg) 18 Amorphous polyester polyol (STEPANPOL PN-110, Tg is 26℃) 20 Liquid polyester polyol (DYNACOLL 7230, hydroxyl value 27-34KOH / mg) 20 Isocyanate MDI 22 Ethylene Vinyl Acetate LEVAMELT 686 20 Adhesion promoter (KH-560) 0.3 Stabilizer (p-toluenesulfonyl isocyanate) 0.1 Antioxidants (1010+168) 0.3 Catalyst A (Stannoic acid) 0.2 Catalyst B (pentamethyldiethylenetriamine) 0.75 Table 2: Composition of raw materials used in Example 2.

[0020] Comparative Example 2 Compared with Example 2, except for the different properties of the amorphous polyester polyol, the other raw material compositions and preparation steps are exactly the same. Example 3

[0021] Compared with Example 1, the difference lies in the raw material composition and ratio design, and the preparation steps are the same.

[0022] raw material Mass fraction Polyether polyol (hydroxyl value 37 KOH / mg) 15 Amorphous polyester polyol (hydroxyl value 56 KOH / mg, Tg 38℃) 15 Liquid polyester polyol (DYNACOLL 7230, hydroxyl value 27-34KOH / mg) 15 Isocyanate MDI 20 Acrylic resin MB3068 (Tg is 51°C) 10 Rosin resin (softening point is 82℃) 10 Polyurethane elastomer (Elastollan SP 9324) 15 Adhesion promoter (KH-560) 0.8 Stabilizer (p-toluenesulfonyl isocyanate) 0.01 Antioxidant (1010) 0.5 Catalyst A (Dibutyltin dilaurate) 0.3 Catalyst B (2,4,6-tris(dimethylaminomethyl)) 0.1 Table 3: Composition of raw materials used in Example 3. Comparative Example 3

[0023] Compared with Example 3, except that Catalyst A is not involved, other raw material compositions and preparation steps are exactly the same. Example 4

[0024] Compared with Example 1, the difference lies in the raw material composition and ratio design, and the preparation steps are the same.

[0025] raw material Mass fraction Polyether polyol (hydroxyl value 56 KOH / mg) 10 Amorphous polyester polyol (hydroxyl value 56 KOH / mg, Tg 38℃) 20 Liquid polyester polyol (DYNACOLL 7255, hydroxyl value 27-34 KOH / mg) 20 Isocyanate MDI 30 Polyurethane elastomer (Elastollan SP 9324) 20 Adhesion promoter (Silquest A-189) 0.5 Stabilizer (p-toluenesulfonyl isocyanate) 0.05 Antioxidant (1010) 0.5 Catalyst A (bismorpholinyl diethyl ether) 0.3 Catalyst B (2,4,6-tris(dimethylaminomethyl)) 0.1 Table 4: Composition of raw materials used in Example 4. Comparative Example 4

[0026] Compared with Example 4, except that the catalyst B is used in excess (specifically 0.3 parts), the other raw material compositions and preparation steps are exactly the same. Example 5

[0027] Compared with Example 1, the difference lies in the raw material composition and ratio design, and the preparation steps are the same.

[0028] raw material Mass fraction Polyether polyol (hydroxyl value 37 KOH / mg) 30 Amorphous polyester polyol (hydroxyl value 56 KOH / mg, Tg 38℃) 10 Liquid polyester polyol (DYNACOLL 7255, hydroxyl value 27-34 KOH / mg) 10 Isocyanate MDI 30 Acrylic resin MB3068 (Tg is 51°C) 10 AMS phenol modified resin (softening point is 75℃) 10 Adhesion promoter (KH-560) 0.5 Stabilizer (polyphosphoric acid) 0.05 Antioxidant (1010) 0.1 Catalyst A (tetrabutyl titanate) 0.25 Catalyst B (1,3,5-tris(dimethylaminopropyl)hexahydrotriazine) 0.05 Table 5: Composition of raw materials used in Example 5.

[0029] The products obtained in the above-mentioned Examples 1-5 and Comparative Examples 1-4 were laminated and applied with PVC films rich in plasticizer (the dyne value of the PVC film used in the actual experiment was 32) of the same batch, respectively. The specific results are shown in Table 6 below.

[0030] Table 6: Performance test results.

[0031] From Table 6 above, it can be clearly seen that the reactive polyurethane hot melt adhesive prepared by Examples 1-5, when applied to a soft PVC film rich in plasticizer, has excellent initial adhesion effect (high initial peel strength), and can also maintain excellent final adhesion effect (high final peel strength after 24 hours, generally exceeding 40N / 25mm, and Examples 1 and 4 even reach the effect of breaking the material), proving that it is not affected by the migration of the plasticizer. In Comparative Example 1, since no catalyst B is used, although it also has a high initial peel strength, the final peel strength of this sample is low, and the bonded PVC film can be easily torn off. In Comparative Example 2, due to the difference in the glass transition temperature of the amorphous polyester polyol, the initial peel strength and final peel strength of the product are both low. The use of catalyst B alone in Comparative Example 3 and the excessive use of catalyst B in Comparative Example 4 will both cause the system to gel prematurely, seriously affecting the final peel strength.

Claims

1. A reactive polyurethane hot melt adhesive for PVC film lamination, characterized in that: It is prepared from the following raw materials in parts by weight: 10-30 parts of polyether polyol; 10-20 parts of amorphous polyester polyol; 10-20 parts of liquid polyester polyol; 0-20 parts of tackifying resin; Thermoplastic resin 0-20 parts; Isocyanate 20-30 parts; Stabilizer 0.01-0.1 parts; Antioxidant 0.1-0.5 parts; Catalyst A 0.1-0.3 part; Catalyst B 0.05-0.1 part; Adhesion promoter 0.3-0.8 parts; The amorphous polyester polyol is an aromatic polyester polyol, and its glass transition temperature is greater than 20°C; The liquid polyester polyol is an aromatic polyester polyol or an aliphatic polyester polyol, and its glass transition temperature is less than -30°C; The catalyst A is one of dibutyltin dilaurate, stannous octoate, tetrabutyl titanate, triethylenediamine, 1,4-dimethylpiperazine, bismorpholinyl diethyl ether, bismorpholinyl triethyl ether, and dimorpholine polyoxyethylene ether; the catalyst B is one of pentamethyldiethylenetriamine, pentamethyldipropylenetriamine, 2,4,6-tris(dimethylaminomethyl)phenol, and 1,3,5-tris(dimethylaminopropyl)hexahydrotriazine; and the mass ratio of the catalyst A to the catalyst B is 2:1-5:

1.

2. The reactive polyurethane hot melt adhesive for PVC film lamination as claimed in claim 1, characterized in that: The mass ratio of the catalyst A to the catalyst B is 3:

1.

3. The reactive polyurethane hot melt adhesive for PVC film lamination as claimed in claim 1, characterized in that: The polyether polyol is selected from one of polyoxypropylene glycol, polyoxyethylene glycol, polyoxypropylene-ethylene glycol, polyoxypropylene triol, or polytetramethylene glycol, and has a number average molecular weight of 400-8000.

4. The reactive polyurethane hot melt adhesive for PVC film lamination as claimed in claim 3, characterized in that: The number average molecular weight of the polyether polyol is 1000-5000.

5. The reactive polyurethane hot melt adhesive for PVC film lamination as claimed in claim 1, characterized in that: The polyacid of the amorphous polyester polyol is selected from at least one of terephthalic acid, phthalic anhydride and isophthalic acid, and the polyol is one or more of ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 2-methyl-1,3-propanediol, 1,4-cyclohexanediol, neopentyl glycol and 3-methyl-1,5-pentanediol.

6. The reactive polyurethane hot melt adhesive for PVC film lamination as claimed in claim 5, characterized in that: The hydroxyl value of the amorphous polyester polyol is 18KOH / mg-56KOH / mg.

7. The reactive polyurethane hot melt adhesive for PVC film lamination as claimed in claim 1, characterized in that: The polyacid of the liquid polyester polyol is selected from at least one of terephthalic acid, phthalic anhydride, isophthalic acid, adipic acid, and sebacic acid, and the polyol is one or more of 1,4-butanediol, 1,6-hexanediol, 2-methyl-1,3-propanediol, 1,4-cyclohexanediol, neopentyl glycol, and 3-methyl-1,5-pentanediol.

8. The reactive polyurethane hot melt adhesive for PVC film lamination as claimed in claim 7, characterized in that: The hydroxyl value of the liquid polyester polyol is 18KOH / mg-34KOH / mg.

9. The reactive polyurethane hot melt adhesive for PVC film lamination as claimed in claim 1, characterized in that: The tackifying resin is selected from one or more of acrylic resin, petroleum resin, rosin resin, terpene resin, poly-α-methylstyrene resin, and indene-coumarone resin; the thermoplastic resin is selected from one or more of ethylene-vinyl acetate, ethylene-vinyl acetate, polyurethane elastomer, high molecular weight polyester resin, and polyolefin resin; the isocyanate is one of diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, isophorone diisocyanate toluene diisocyanate, hexamethylene diisocyanate, and dicyclohexylmethane diisocyanate; the stabilizer is One of phosphoric acid, polyphosphoric acid, p-toluenesulfonyl isocyanate, sebacic acid, benzoyl chloride, and azelaic acid; the antioxidant brand is 1010, 168, 1035, 1076, 1135, 5057, or one of triphenyl phosphite; the adhesion promoter is one of γ-aminopropyl triethoxysilane, γ-glycidyloxypropyl trimethoxysilane, benzylaminomethyl triethoxysilane, benzylaminopropyl trimethoxysilane, γ-methacryloxypropyl trimethoxysilane, γ-mercaptopropyl triethoxysilane, and γ-mercaptopropyl trimethoxysilane.

10. The method for preparing a reactive polyurethane hot melt adhesive for PVC film lamination according to any one of claims 1 to 9, characterized in that: The steps include: (1) According to the preset proportion, the stabilizer, antioxidant, tackifying resin and thermoplastic resin are put into a vacuum reactor, the temperature is raised to 140°C, and the mixture is mixed, stirred and melted; (2) Add polyether polyol, amorphous polyester polyol and liquid polyester polyol, stir and melt, and dehydrate for 1h-2h under vacuum ≤-0.098MPa; (3) Cool down to 100°C, add isocyanate, mix and stir evenly, then heat up to 120°C and react for 1 hour; (4) Adding catalyst A, catalyst B and adhesion promoter, and performing vacuum degassing reaction for 0.5h-1h; (5) After unloading, sealing and packaging, it is ready.