High-temperature-cooking-resistant easy-to-tear cover coating and application thereof

Abstract

The invention belongs to the technical field of easy-to-tear cover coatings, and discloses a high-temperature-cooking-resistant easy-to-tear cover coating which comprises the following main components: 10-95% of polyester resin, 0.1-60% of a curing agent, 0.001-3% of an auxiliary agent, 0-25% of a pigment and 30-75% of a solvent. Through the design of tinplate, an aluminum easy-to-tear cover metal cover ring and food and medicine packaging, the coating has excellent adhesion performance, successfully solves the problem of heat bonding with various film heat-sealing base materials, ensures tight bonding between the coating and the film heat-sealing base materials, and does not have good adhesion after 60 minutes even in a cooking test at the high temperature of 121 DEG C and the pressure of 0.2 MPa. According to the present invention, the coating has characteristics of no glue failure, no shedding, excellent sealing performance, no corrosion after the soaking test with 50 Kg impact 20% copper sulfate, and more importantly, the strict test verifies that the components of the coating are safe and harmless and do not release any harmful substance when the coating is in contact with the food so as to completely meet the safety standard of food packaging.

Description

Technical Field

[0001] The invention belongs to the technical field of easy-tear cover coatings, in particular to a high-temperature cooking-resistant easy-tear cover coating and application thereof. Background Art

[0002] As consumers pay more and more attention to food safety and health, the market's requirements for food packaging materials are also getting higher and higher.

[0003] China has made some progress in the research and development of high temperature resistant retort and easy-to-tear cover coatings. For example, some research institutions and enterprises have developed aluminum-plastic composite high temperature resistant retort and easy-to-tear covers based on PA materials and preparation methods. Chinese patent number CN108137979B discloses a preparation method of ethylene vinyl acetate copolymer water-based heat-seal coating; CN200810095147.8 discloses the preparation of heat-sealable coatings by olefin copolymer modified resins;

[0004] Chinese patent number 0N202111194588.5 discloses a method for preparing a heat-sealing coating for an aluminum foil lunch box, which also uses a polyolefin aqueous dispersion as the main film-forming resin;

[0005] Chinese patent number CN200510122913.1 discloses a heat-sealing coating for aluminum foil of a heater and its preparation. This technology also uses thermoplastic ternary chloroacetic acid resin as the main film-forming agent. The coating produced by the above technology is aimed at the heat-sealing coating of easy-to-tear cover film. Since there is no corresponding cover ring coating to match it, the use of existing cover ring coatings cannot meet the requirements of high-temperature steaming and sterilization. These products have good barrier properties, non-toxic, odorless, beautiful, easy to open and other advantages, but cannot meet the requirements of high temperature resistance and high-pressure water boiling steam sterilization of food.

[0006] While traditional canned food packaging materials bring convenience, they are also accompanied by some problems. The opening process is often difficult and requires the use of tools or a lot of strength. It is not only inconvenient to operate, but also easy to cause scratches on the hands when opening. In addition, the safety of some canned packaging materials is relatively low. They may contain substances that are harmful to the human body or release harmful substances at high temperatures. These problems have affected consumers' experience and also caused people to worry about the safety of canned food packaging, so it needs to be modified and optimized. Summary of the invention

[0007] The purpose of the present invention is to provide a high temperature resistant retort easy-tear cover coating and its application, so as to solve the problems raised in the above background technology.

[0008] In order to achieve the above purpose, the present invention provides the following technical solution: a high temperature resistant steaming and easy-to-tear cover coating, the main components of which are 10-95% polyester resin, 0.1-60% curing agent, 0.001-3% auxiliary agent, 0-25% pigment and 30-75% solvent.

[0009] Preferably, the coating is prepared by:

[0010] A1, add raw materials: first add resin, additives, pigments and solvents according to the formula ratio;

[0011] A2, grinding, grinding resin, additives, pigments and solvents by grinding wheels;

[0012] A3, repackaging, add curing agent when grinding to appropriate fineness, filter and repackaging.

[0013] Preferably, the polyester resin can be selected from one or more combinations of a linear polyester resin having an acid value of less than 5 mgKOH / g and a hydroxyl value of less than 20 mgKOH / g and a branched polyester resin having an acid value of less than 100 mgKOH / g and a hydroxyl value of less than 500 mgKOH / g.

[0014] Preferably, the curing agent comprises one or a combination of blocked isocyanate, methyl etherified melamine resin, benzoguanamine resin and phenolic resin;

[0015] The pigment comprises one or more of BASF Paliotol Yellow K1800, BASF Heliogen K7090, Clariant D3G Red and BASF Paliogen Red K3580.

[0016] Preferably, the auxiliary agent comprises one or more combinations of a wetting agent, a leveling agent and a defoaming agent;

[0017] The solvent comprises one or more of methyl ethyl ketone, 100# solvent oil, xylene, butyl acetate, propylene glycol methyl ether acetate, dipropylene glycol methyl ether, ethylene glycol butyl ether, isophorone, 1,4-dioxane, tetrahydrofuran, cyclohexanone, methyl nylonate, diethyl carbonate, N-ethyl pyrrolidone and ethylene glycol butyl ether acetate.

[0018] Preferably, the grinding fineness of A3 is in the range of 2 to 10 microns, and the number average molecular weight of the polyester resin is between 1000 and 200000.

[0019] Preferably, the coating has a baking temperature of 180-204° C. and a baking time of 10-18 min.

[0020] Preferably, the coating is mainly used in the field of easy-tear metal cover ring coating, food packaging box and medical packaging.

[0021] The beneficial effects of the present invention are as follows:

[0022] The present invention has excellent adhesion performance through the design of tinplate and aluminum easy-tear metal cover rings as well as food and medical packaging, successfully solving the problem of thermal bonding with a variety of film heat-sealed substrates, and ensuring the tight bonding between the coating and the film heat-sealed substrate. Even in the cooking test at a high temperature of 121°C and a pressure of 0.2MPa, after 60 minutes, the coating still remains glue-free and does not fall off, showing excellent sealing performance. In addition, the coating also has the advantages of butanone wiping resistance and adhesion of level 1, and excellent impact resistance. After a 50Kg impact and 20% copper sulfate immersion test, there is no corrosion. More importantly, after rigorous testing and verification, its ingredients are safe and harmless when in contact with food, and will not release any harmful substances, which fully meets the safety standards for food packaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Create a flow chart for the present invention;

[0024] Figure 2 This is a coating composition diagram of Examples 1 to 4 of the present invention;

[0025] Figure 3 This is a coating composition diagram of Examples 5 to 8 of the present invention;

[0026] Figure 4 This is a test result diagram of an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in 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.

[0028] like Figures 1 to 4 As shown, the embodiment of the present invention provides a high temperature resistant steaming and easy-tear cover coating, the main components of which are 10-95% polyester resin, 0.1-60% curing agent, 0.001-3% auxiliary agent, 0-25% pigment and 30-75% solvent.

[0029] Through the design of tinplate and aluminum easy-tear metal cover rings as well as food and medical packaging, it has excellent adhesion performance, successfully solved the problem of thermal bonding with a variety of film heat-sealed substrates, and ensured the tight bonding between the coating and the film heat-sealed substrate. Even in the cooking test at a high temperature of 121°C and a pressure of 0.2MPa, after 60 minutes, the coating remained glue-free and did not fall off, showing excellent sealing performance. In addition, the coating also has the advantages of butanone wiping resistance and adhesion level 1, and excellent impact resistance. After a 50Kg impact test and 20% copper sulfate immersion test, there was no corrosion. More importantly, after rigorous testing and verification, its ingredients are safe and harmless when in contact with food, and will not release any harmful substances, which fully meets the safety standards for food packaging.

[0030] The preparation method of the coating is as follows:

[0031] A1, add raw materials: first add resin, additives, pigments and solvents according to the formula ratio;

[0032] A2, grinding, grinding resin, additives, pigments and solvents by grinding wheels;

[0033] A3, repackaging, add curing agent when grinding to appropriate fineness, filter and repackaging.

[0034] The polyester resin may be selected from one or more combinations of a linear polyester resin having an acid value of less than 5 mgKOH / g and a hydroxyl value of less than 20 mgKOH / g and a branched polyester resin having an acid value of less than 100 mgKOH / g and a hydroxyl value of less than 500 mgKOH / g.

[0035] By selecting polyester resins with specific performance parameters, including the control of acid value and hydroxyl value, linear polyester resins with acid value less than 5 mgKOH / g and hydroxyl value less than 20 mgKOH / g provide good processing stability and thermal stability, while branched polyester resins with acid value less than 100 mgKOH / g and hydroxyl value less than 500 mgKOH / g bring higher flexibility and adhesion. Selecting one or more combinations of these polyester resins can effectively improve the performance of the coating on the high temperature cooking resistant easy-tear cover, ensure the integrity, tearability and safety of the package, and meet the high standards of the food packaging industry.

[0036] Wherein, the curing agent comprises one or a combination of blocked isocyanate, methyl etherified melamine resin, benzoguanamine resin and phenolic resin;

[0037] The pigment includes one or more of BASF Paliotol Yellow K1800, Phthalocyanine Blue BASF Heliogen K7090, Clariant D3G Red and BASF Paliogen Red K3580.

[0038] By using these curing agents alone or in combination, the crosslinking density and curing speed of the coating can be significantly improved, and the hardness, abrasion resistance and chemical resistance of the coating can be enhanced. At the same time, they also help to improve the heat resistance and weather resistance of the coating, ensuring long-lasting protection and stability in food packaging applications, meeting the high quality requirements for packaging materials.

[0039] The advantages of pigments such as bright colors, light and heat resistance, and good stability can give the coating good color effects and visual beauty, while meeting the strict requirements of food packaging for pigment safety and environmental protection.

[0040] The additives include one or more combinations of wetting agents, leveling agents and defoamers;

[0041] The solvent includes one or more of methyl ethyl ketone, 100# solvent oil, xylene, butyl acetate, propylene glycol methyl ether acetate, dipropylene glycol methyl ether, ethylene glycol butyl ether, isophorone, 1,4-dioxane, tetrahydrofuran, cyclohexanone, methyl nylonate, diethyl carbonate, N-ethyl pyrrolidone and ethylene glycol butyl ether acetate.

[0042] By improving the wettability and fluidity of the coating, promoting uniform distribution of the coating, eliminating bubbles, ensuring a smooth and flat coating surface, and improving the overall coating effect and coating quality;

[0043] By using these solvents alone or in combination, the viscosity of the coating can be adjusted, improving its fluidity and construction performance, while ensuring that the coating can dry evenly during the curing process and improving the gloss and adhesion of the coating.

[0044] Among them, the grinding fineness range in A3 is 2~10 microns, and the number average molecular weight of the polyester resin is between 1000-200000.

[0045] By controlling the grinding fineness within the range of 2-10 microns, it helps to improve the uniformity, adhesion and glossiness of the coating. At the same time, the number average molecular weight of the polyester resin is between 1000-200000, which ensures the stability and performance of the coating. The two work together to make the coating smoother and more continuous, meeting the high quality requirements of easy-to-tear coatings.

[0046] The baking temperature of the coating is 180-204°C, and the baking time is 10-18 minutes.

[0047] By baking the coating at 180-204℃ for 10-18 minutes, the coating can be ensured to cure quickly, improve adhesion and cooking resistance, and meet the technical requirements of easy-tear cover coatings.

[0048] Among them, the coating is mainly used in the field of easy-tear metal cover ring coating, food packaging box and medical packaging.

[0049] By optimizing the formulation of pigments, solvents and additives, the color, fluidity and construction performance of the coating are improved, ensuring that the coating is resistant to high-temperature cooking, easy to tear, safe and environmentally friendly, and meeting the high standards required for food and pharmaceutical packaging.

[0050] The test method for the coating performance is:

[0051] 1. Water boiling resistance: the sample is placed in a pressure cooker at 121°C and a pressure of 0.2MPa, and boiled for 60 minutes. The sample is considered qualified if there is no whitening, bubbles, debonding, or corrosion.

[0052] 2. Butanone resistant wiping: according to method HG / T 3830-2006 Appendix A;

[0053] 3. Adhesion test: Tested according to method GB / T 9286-2021;

[0054] 4. Impact resistance test: Test according to method GB / T 1732-2020, and then soak in 20% copper sulfate. It is qualified if there is no corrosion point;

[0055] 5. Peel strength test of PP film, composite aluminum foil, PE film and cover ring coating after heat sealing. Referring to the 180° peel strength test method of adhesive in GB-T2790-1995, the above-mentioned samples and PP or PE, composite aluminum foil are made into 200mm*25mm strips, hot-pressed at 200℃ for 0.1~1s, pressure 0.05~0.3Mpa, hot-pressed, and tested for 180° peel strength after bonding.

[0056] Example 1 The coating uses 20% ES680 polyester resin (SK Chemical Company), 5% CL271 polyester resin (Suzhou Hanhai New Materials Company), 4% CYMEL 303LF curing agent (Zhanxin Resin Co., Ltd.), 0.02% PPW-0901 polyethylene wax additive (Nanjing Tianshi New Materials Company), and 55.9% mixed solvent;

[0057] Example 2 The coating uses 50% ES660 polyester resin (SK Chemical Company), 7% CYMEL 303LF curing agent (Allen Resin Co., Ltd.), 0.02% PPW-0901 polyethylene wax additive (Nanjing Tianshi New Materials Company) and 0.2% MODAREZ PW 336 (France Centron Company polyacrylate additive), and 42.78% mixed solvent;

[0058] Example 3 The coating uses 35% ES660 polyester resin (SK Chemical Company), 5% CL271 polyester resin (Suzhou Hanhai New Materials Company), 4% CYMEL 303LF curing agent (Zhanxin Resin Co., Ltd.), 4% Desmodur BL2078-2 curing agent (Covestro), 0.02% PPW-0901 polyethylene wax additive (Nanjing Tianshi New Materials Company), and 51.98% mixed solvent;

[0059] Example 4 The coating uses 25% CH492 polyester resin (Suzhou Hanhai New Materials Co., Ltd.), 4% CL150 polyester resin (Suzhou Hanhai New Materials Co., Ltd.), 8% CYMEL1 123 curing agent (Zhanxin Resin Co., Ltd.), 0.04% PPW-0901 polyethylene wax additive (Nanjing Tianshi New Materials Co., Ltd.) and 62.96% mixed solvent;

[0060] Example 5 The coating uses 20% ES460 polyester resin (SK Chemical Company), 5% CL271 polyester resin (Suzhou Hanhai New Materials Company), 4% CYMEL 303LF curing agent (Zhanxin Resin Co., Ltd.), 0.02% PPW-0901 polyethylene wax additive (Nanjing Tianshi New Materials Company) and 55.9% mixed solvent;

[0061] Example 6 The coating uses 40% ES410 polyester resin (SK Chemical Company), 10% ES812 polyester resin (Suzhou Hanhai New Materials Company), 10% CYMEL 303LF curing agent (Zhanxin Resin Co., Ltd.), 0.02% PPW-0901 polyethylene wax additive (Nanjing Tianshi New Materials Company) and 39.98% mixed solvent;

[0062] The coating of Example 7 uses 25% C5401F polyester resin (Suzhou Hanhai New Materials Co., Ltd.), 5% CL150 polyester resin (Suzhou Hanhai New Materials Co., Ltd.), 4% CYMEL 303L curing agent (Zhanxin Resin Co., Ltd.), 4% Desmodur BL 2078-2 curing agent (Covestro), 0.02% PPW-0901 polyethylene wax additive (Nanjing Tianshi New Materials Co., Ltd.), 3% Paliotol Yellow K1800 pigment (BASF) and 58.98% mixed solvent;

[0063] The coating of Example 8 uses 100% 3N2006-745YY (Suzhou Sanxin Material Technology Co., Ltd.).

[0064] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0065] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. High temperature resistant cooking easy-tear cover coating, characterized by: The main components of the coating are 10-95% of polyester resin, 0.1-60% of curing agent, 0.001-3% of auxiliary agent, 0-25% of pigment and 30-75% of solvent.

2. The high temperature resistant retort and easy-tear cover coating according to claim 1, characterized in that: The method for making the coating is as follows: A1, add raw materials: first add polyester resin, additives, pigments and solvents according to the formula ratio; A2, grinding, grinding resin, additives, pigments and solvents by grinding wheels; A3, repackaging, add curing agent when grinding to appropriate fineness, filter and repackaging.

3. The high temperature resistant retort and easy-tear cover coating according to claim 1, characterized in that: The polyester resin may be selected from one or more combinations of a linear polyester resin having an acid value of less than 5 mgKOH / g and a hydroxyl value of less than 20 mgKOH / g and a branched polyester resin having an acid value of less than 100 mgKOH / g and a hydroxyl value of less than 500 mgKOH / g.

4. The high temperature resistant retort and easy-tear cover coating according to claim 1, characterized in that: The curing agent comprises one or more combinations of blocked isocyanate, methyl etherified melamine resin, benzoguanamine resin and phenolic resin; The pigment comprises one or more of BASF Paliotol Yellow K1800, BASF Heliogen K7090, Clariant D3G Red and BASF Paliogen Red K3580.

5. The high temperature resistant retort and easy-tear cover coating according to claim 1, characterized in that: The auxiliary agent comprises one or more combinations of wetting agents, leveling agents and defoaming agents; The solvent comprises one or a combination of methyl ethyl ketone, 100# solvent oil, xylene, butyl acetate, propylene glycol methyl ether acetate, dipropylene glycol methyl ether, ethylene glycol butyl ether, isophorone, 1,4-dioxane, tetrahydrofuran, cyclohexanone, methyl nylonate, diethyl carbonate, N-ethyl pyrrolidone and ethylene glycol butyl ether acetate.

6. The high temperature resistant retort and easy-tear cover coating according to claim 2, characterized in that: The grinding fineness of A3 is in the range of 2-10 microns, and the number average molecular weight of the polyester resin is between 1000-200000.

7. The high temperature resistant retort and easy-tear cover coating according to claim 1, characterized in that: The coating has a baking temperature of 180-204°C and a baking time of 10-18 minutes.

8. The use of the high temperature resistant retort easy-tear cover coating according to claim 1, characterized in that: The coating is mainly used in the field of easy-tear metal cover ring coating, food packaging box and medical packaging.

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