Heat sealing adhesive for easy-to-tear cover for food metal packaging container and preparation method of heat sealing adhesive

Abstract

The invention relates to the technical field of heat sealing adhesives, in particular to a heat sealing adhesive for an easy-to-tear cover for a food metal packaging container and a preparation method of the heat sealing adhesive. The preparation raw materials at least comprise the following components: 60-80 parts of a bisphenol A epoxy resin solution, 3-20 parts of a curing agent, 0.05-0.5 part of a catalyst, 0.5-7 parts of a heat-sealing material, 0-0.5 part of a defoaming agent, 0-2 parts of a lubricant and 0.5-10 parts of an organic solvent, products with different colors and appearances and different heat-sealing strengths are obtained by optimizing a product formula system, the application range is wide, construction is convenient, and the cost is low. The large-scale industrial production and application are easy.

Description

Technical Field

[0001] The invention relates to the technical field of heat-sealing adhesives, in particular to a heat-sealing adhesive for an easy-tear cover of a metal food packaging container and a preparation method thereof. Background Art

[0002] The product structure and coating requirements of metal food packaging containers vary according to different application scenarios. Under the premise of ensuring the sealing of the package, the tear-off cover is widely used in the packaging of dry goods, milk powder and canned food because it is easy to open and not easy to hurt people. The cover body of the tear-off cover is mainly composed of a metal cup ring and a cover film (composite aluminum foil or composite film). The cover film is bonded to the cup ring by heat sealing to form a complete tear-off cover. The tear-off cover is used in conjunction with the can body (body). After the can body is filled with food, it is sealed with the tear-off cover. Among them, the outer coating of the cup ring of the tear-off cover, in addition to the adhesion, impact resistance and scratch resistance of conventional coatings, also needs to have heat sealability, good heat sealing strength and suitable opening force with the cover film. It is used for high-temperature sterilization products and must withstand high-temperature sterilization at 121-127°C for 30-120 minutes.

[0003] A Chinese patent (publication number CN101679645A) discloses a protective sealable coating composition, which is prepared by reacting a polypropylene polymer having sufficient carboxylic acid and / or carboxylic anhydride groups with an acid value of 2-50 mg KOH / g non-volatile polymer with a second polymer. The coating has good flexibility, adhesion, bactericidal resistance, stability and anti-blushing properties. However, the dispersion requires polypropylene resin and epoxy resin to be mixed with an organic solvent in a screw mixing extruder to form a dispersion, which is prone to sedimentation and difficult to redisperse, making construction inconvenient, limiting its large-scale application. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a heat-sealing adhesive for an easy-tear cover for a metal food packaging container. By optimizing the product formula system, products with different colors and appearances and different heat-sealing strengths are obtained. The product has a wide range of applications, is easy to construct, and is easy to apply in large-scale industrial production.

[0005] On the one hand, the present invention provides a heat-sealing adhesive for an easy-tear cover for a metal food packaging container. The raw materials for preparing the heat-sealing adhesive include at least the following components, by weight: 60-80 parts of a bisphenol A epoxy resin solution, 3-20 parts of a curing agent, 0.05-0.5 parts of a catalyst, 0.5-7 parts of a heat-sealing material, 0-0.5 parts of a defoaming agent, 0-2 parts of a lubricant, and 0.5-10 parts of an organic solvent.

[0006] As a preferred technical solution, the mass concentration of bisphenol A epoxy resin in the bisphenol A epoxy resin solution is 10-60%, preferably 40-50%.

[0007] As a preferred technical solution, the solvent in the bisphenol A epoxy resin solution is selected from at least one of n-butanol, xylene, trimethylbenzene, propylene glycol methyl ether acetate, ethylene glycol monobutyl ether, DBE, isophorone and cyclohexanone.

[0008] As a preferred technical solution, the bisphenol A epoxy resin in the bisphenol A epoxy resin solution has an epoxy equivalent of 1000-5000 g / eq, preferably 1500-3000 g / eq. Preferably, the bisphenol A epoxy resin is selected from at least one of Nan Ya Epoxy NPES607, Nan Ya Epoxy NPES627, Nan Ya Epoxy NPES628, Nan Ya Epoxy NPES629, Nan Ya Epoxy NPES907, Nan Ya Epoxy NPES909, Nan Ya Epoxy NPES909H, Guodu Epoxy YD017, Guodu Epoxy YD019, and Guodu Epoxy YD019H.

[0009] Preferably, the bisphenol A epoxy resin solution is a combination of 40 wt % Nan Ya Epoxy NPES909 solution and 40 wt % Nan Ya Epoxy NPES907 solution.

[0010] Preferably, the mass ratio of 40 wt % Nan Ya epoxy NPES909 solution to 40 wt % Nan Ya epoxy NPES907 solution is (4-6):(1-3), preferably 5:2.

[0011] As a preferred technical solution, the curing agent is selected from at least one of amino resin, blocked isocyanate curing agent and phenolic resin, preferably amino resin or phenolic resin.

[0012] As a preferred technical solution, the amino resin is selected from melamine resin and / or benzoguanamine resin.

[0013] Preferably, the amino resin is selected from at least one of allnex CYMEL 303, allnex CYMEL 325, allnex CYMEL 659, allnex CYMEL 1123, INEOX DSM BF892, and INEOX CE8824, preferably INEOX DSM BF892.

[0014] As a preferred technical solution, the blocked isocyanate curing agent is selected from Bayer Desmodur BL3175SN, VP LS2078 / 2, EVONIK VESTANAT B1358A, At least one of EP-B1186A.

[0015] As a preferred technical solution, the phenolic resin is selected from PHENODUR-PR285, PHENODUR-612, PHENODUR-PR401, PHENODUR-PR411, PHENODUR-515, PHENODUR-PR516, PHENODUR-PR612, PHENODUR-PR307, PHENODUR-PR308, PHENODUR-PR566, PHENODUR-PR1775, PHENODUR-1785, Sumitomo Chemical PR-55887, Sumitomo Chemical PR-34419, Sumitomo Chemical PR-55966, Sumitomo Chemical PR-56103, Sumitomo Chemical At least one of PR-33356.

[0016] Preferably, the phenolic resin is selected from PHENODUR-PR516, PHENODUR-PR285, Sumitomo Chemical One of the PR-55887.

[0017] As a preferred technical solution, the catalyst is an acid catalyst, and the acid catalyst is selected from at least one of DNNSA (dinonylnaphthalenesulfonic acid), DNNDSA (dinonylnaphthalene disulfonic acid), DBBSA (dodecylbenzenesulfonic acid) and its blocked substances, phosphoric acid and its derivatives.

[0018] Preferably, the acid catalyst is selected from at least one of King's Chemical NACURE K155, King's Chemical NACURE 1051, King's Chemical NACURE 5076, King's Chemical NACURE 5225, King's Chemical NACURE 5925, King's Chemical NACURE 59254046, King's Chemical NACURE, allnex CYCAT 500, allnex CYCAT 600, allnex CYCAT 296-9, allnex CYCAT XK-406N, and American Gasification T-12.

[0019] Preferably, the acid catalyst is allnex CYCAT XK-406N or a combination of allnex CYCAT XK-406N and King's Chemical NACURE5925.

[0020] Preferably, the mass ratio of the allnex CYCAT XK-406N to King's Chemical NACURE5925 is (1-2):(0.05-0.2), preferably 2:0.1.

[0021] As a preferred technical solution, the heat-sealing material is selected from at least one of oxidized polyethylene, maleic anhydride grafted PE wax, maleic anhydride grafted PP wax, and maleic anhydride grafted dispersion.

[0022] As a preferred technical solution, the melting point of the heat sealing material is ≥100°C, preferably ≥120°C, and most preferably 130-165°C.

[0023] As a preferred technical solution, the acid value of the heat-sealing material is 10-50KOH / g.

[0024] Preferably, the oxidized polyethylene is selected from Honeywell A-6, ceronas At least one of 816.

[0025] Preferably, the maleic anhydride grafted PE wax is selected from at least one of COACE W1H of COACE Chemical and Westlake EPOLENE C-16 of Westlake Chemical.

[0026] Preferably, the maleic anhydride grafted PP wax is selected from at least one of ClariantLI COCENE PP MA 6452TP, Westlake epolene E-43, CERONAS ADDIMER 840rR, COACE B1A and COACE B1AB2, preferably Westlake epolene E-43.

[0027] Preferably, the maleic anhydride grafted dispersion is at least one selected from MORPRIME 78HB70APC, MORPRIME 78HB74C, MORPRIME 78LJ10C, and MORPRIME 78LJ8APC, preferably MORPRIME 78LJ10C.

[0028] Preferably, the heat sealing material is a combination of maleic anhydride grafted PP wax and maleic anhydride grafted dispersion.

[0029] Preferably, the mass ratio of the maleic anhydride grafted PP wax to the maleic anhydride grafted dispersion is (2-3):(10-15).

[0030] As a preferred technical solution, the organic solvent is selected from at least one of propylene glycol methyl ether acetate (PMA), ethylene glycol ethyl ether acetate (CAC), diacetone alcohol (DAA), dibasic acid ester (DBE), ethylene glycol butyl ether (BCS), diisobutyl ketone (DIBK), ethylene glycol butyl ether acetate (BGA), and propylene glycol methyl ether propionate (PMP).

[0031] Preferably, the organic solvent is a combination of dibasic acid ester (DBE) and ethylene glycol butyl ether (BCS), and the mass ratio of the dibasic acid ester (DBE) and ethylene glycol butyl ether (BCS) is (0.5-2):1, preferably 1:1.

[0032] The heat-sealing adhesive provided by the present invention optimizes the coordination of bisphenol A epoxy resin, curing agent and heat-sealing material in the system, so that the provided product can be applied to sealing packaging in different scenarios, including dry goods and high-temperature cooking easy-tear covers. Specifically, by using Nan Ya Epoxy NPES909 and Nan Ya Epoxy NPES907 as the resin matrix, using amino resin or phenolic resin as the curing agent, and introducing heat-sealing materials with polar reactive groups, the coating is endowed with excellent heat-sealing properties, and the peel strength after heat-sealing with PE or PP film is ≥12N / 15mm.

[0033] The heat-sealing adhesive provided by the invention is used for dry goods formulas. After cans (bowls) are made and sealed, the adhesive does not crack for 30 minutes at 80°C, and does not crack for 2 minutes in a pressure resistance test of ≥0.20MPa.

[0034] The heat-sealing adhesive provided by the invention is used for high-temperature cooking formulas. After cans (bowls) are made and sealed, it can withstand 121°C and 30 minutes of cooking (reverse pressure cooker) without cracking, and the peel strength is ≥5N / 15mm.

[0035] Another aspect of the present invention provides a method for preparing a heat-sealing adhesive for an easy-tear cover for a metal food packaging container, which comprises at least the following steps: adding a bisphenol A epoxy resin solution, a curing agent, a catalyst, a heat-sealing material, a defoaming agent, a lubricant, and an organic solvent into a container and stirring and mixing to obtain the adhesive.

[0036] Beneficial Effects

[0037] 1. The present invention provides a heat-sealing adhesive for an easy-tear cover for a metal food packaging container. By optimizing the product formula system, products with different colors and appearances and different heat-sealing strengths are obtained. The product has a wide range of applications, is easy to construct, and is easy to apply in large-scale industrial production.

[0038] 2. The heat-sealing adhesive provided by the present invention optimizes the combination of bisphenol A epoxy resin, curing agent and heat-sealing material in the system, so that the provided product can be suitable for sealing packaging in different scenarios, including dry goods and high-temperature cooking easy-tear covers.

[0039] 3. The present invention adopts Nan Ya Epoxy NPES909 and Nan Ya Epoxy NPES907 as the resin matrix, adopts amino resin or phenolic resin as the curing agent, and introduces heat-sealing materials with polar reactive groups to give the coating excellent heat-sealing properties. The peel strength after heat-sealing with PE or PP film is ≥12N / 15mm.

[0040] 4. The heat-sealing adhesive provided by the present invention is used for dry goods formulas. After the cans (bowls) are sealed, they will not crack for 30 minutes at 80°C, and will not crack for 2 minutes when subjected to a pressure test of ≥0.20 MPa.

[0041] 5. The heat-sealing adhesive provided by the present invention is used for high-temperature cooking formulas. After the cans (bowls) are sealed, they can withstand 121°C and 30 minutes of cooking (reverse pressure cooker) without cracking, and the peel strength is ≥5N / 15mm. DETAILED DESCRIPTION

[0042] Examples 1-5, Comparative Examples 1-4

[0043] Examples 1-5 and Comparative Examples 1-4 of the present invention provide a heat-sealing adhesive for an easy-tear cover for a metal food packaging container, and the formula is shown in Table 1 in parts by weight.

[0044] Table 1

[0045]

[0046]

[0047] On the other hand, Examples 1-5 and Comparative Examples 1-4 of the present invention provide a method for preparing a heat-sealing adhesive for an easy-tear lid for a metal food packaging container, comprising the following steps: crushing the maleic anhydride grafted PP wax to D50 < 10 μm by air flow crushing technology, pre-dispersing it with an organic solvent, and stirring and mixing it with other raw materials in Table 1 to obtain the obtained product.

[0048] Performance Testing

[0049] The heat seal adhesive provided in Examples 1-5 and Comparative Examples 1-4 was coated on an aluminum plate using a wire rod coater and cured in a hot air heating oven at 200° C. for 10 minutes to obtain a dry film weight of 10±0.5 g / m 2 The coating was observed and the color of the coating was recorded in Table 2. The coating was heat-sealed with the CPP film (cast polypropylene protective film) by a heat-sealing instrument, under a pressure of 0.5 MPa, the heat-sealing temperature was 200°C, and maintained for 1 second. The peel strength was tested by a tensile instrument. The test results are shown in Table 2.

[0050] Table 2

[0051]

Claims

1. A heat-sealing adhesive for an easy-tear cover for a metal food packaging container, characterized in that: The raw materials for its preparation include at least the following components by weight: 60-80 parts of bisphenol A epoxy resin solution, 3-20 parts of curing agent, 0.05-0.5 parts of catalyst, 0.5-7 parts of heat sealing material, 0-0.5 parts of defoaming agent, 0-2 parts of lubricant and 0.5-10 parts of organic solvent.

2. The heat-sealing adhesive for an easy-tear cover for a metal food packaging container according to claim 1, characterized in that: The solvent in the bisphenol A epoxy resin solution is selected from at least one of n-butanol, xylene, trimethylbenzene, propylene glycol methyl ether acetate, ethylene glycol monobutyl ether, DBE, isophorone and cyclohexanone.

3. The heat-sealing adhesive for an easy-tear cover for a metal food packaging container according to claim 2, characterized in that: The epoxy equivalent of the bisphenol A epoxy resin in the bisphenol A epoxy resin solution is 1000-5000 g / eq.

4. The heat-sealing adhesive for an easy-tear cover for a metal food packaging container according to claim 3, characterized in that: The curing agent is selected from at least one of amino resin, blocked isocyanate curing agent and phenolic resin.

5. The heat-sealing adhesive for an easy-tear cover for a metal food packaging container according to claim 4, characterized in that: The amino resin is selected from melamine resin and / or benzoguanamine resin.

6. The heat-sealing adhesive for an easy-tear cover for a metal food packaging container according to claim 5, characterized in that: The catalyst is an acid catalyst.

7. The heat-sealing adhesive for an easy-tear cover for a metal food packaging container according to claim 6, characterized in that: The heat-sealing material is selected from at least one of oxidized polyethylene, maleic anhydride grafted PE wax, maleic anhydride grafted PP wax, and maleic anhydride grafted dispersion.

8. The heat-sealing adhesive for the easy-tear cover for metal food packaging container according to claim 7, characterized in that: The melting point of the heat sealing material is ≥100°C.

9. The heat-sealing adhesive for an easy-tear cover for a metal food packaging container according to claim 8, characterized in that: The acid value of the heat sealing material is 10-50 KOH / g.

10. A method for preparing the heat-sealing adhesive for an easy-tear cover for a metal food packaging container according to any one of claims 1 to 9, characterized in that: The following steps are involved: The bisphenol A epoxy resin solution, curing agent, catalyst, heat sealing material, defoaming agent, lubricant and organic solvent are added into a container and stirred and mixed to obtain the product.

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