Medium-resistant polyol as well as preparation method and application thereof

Abstract

The invention relates to the technical field of adhesives, in particular to medium-resistant polyol as well as a preparation method and application thereof. The media-resistant polyol contains a media-resistant aliphatic long segment as a backbone and contains pendant group structures, such as amide groups, polyurea groups and cyclic structures, that are stable to high-temperature cooking and water cooking media. The side group structures endow the film with excellent wettability with the surface of a film substrate. In addition, the side base structures further enhance the bonding strength of the packaging bag and the aluminum foil, the packaging bag shows excellent tolerance to a medium in a high-temperature environment, the bonding interface of the aluminum foil and the plastic film can be effectively protected against damage, and therefore the overall performance of the packaging bag is improved. When the medium-resistant polyhydric alcohol is applied to a double-component solvent-free food aluminum foil flexible package laminated adhesive, after food containing ethyl maltol is packaged, a packaging bag has outstanding resistance to ethyl maltol and edible oil media under the condition of high-temperature cooking.

Description

Technical Field

[0001] The present invention relates to the technical field of adhesives, and in particular to a medium-resistant polyol and a preparation method and application thereof. Background Art

[0002] Aluminum foil medium-resistant two-component solvent-free food aluminum foil flexible packaging laminating adhesive occupies a significant share in the market. Aluminum foil aluminum-plastic flexible packaging, with its excellent oxygen and water barrier properties, effectively prevents packaged food from spoiling and extends the shelf life. Especially at a time when demand for fast-cooked food, pre-prepared dishes and high-quality food is growing, the use of aluminum-plastic packaging continues to rise, and its convenience is favored. At the same time, with the improvement of environmental protection standards and customers' pursuit of composite efficiency, solvent-free polyurethane packaging laminating adhesives have gradually replaced solvent-based packaging laminating adhesives and become the new favorite of the market. Despite this, compared with solvent-based polyurethane flexible packaging laminating adhesives, solvent-free products still have room for improvement in performance and stability.

[0003] At present, aluminum foil medium-resistant two-component solvent-free food aluminum foil flexible packaging coating adhesive is facing a series of challenges. For aluminum-plastic composite flexible packaging with more stringent requirements, its bonding strength to the aluminum foil surface still needs to be improved compared with solvent-based polyurethane flexible packaging coating adhesive. In addition, the resistance of the coating adhesive to ethyl maltol and edible oil media needs to be further enhanced. The solvent-free flexible packaging adhesives in the existing technology are mainly composed of isocyanates and polyols. Solvent-free flexible packaging adhesives using ordinary polyether polyols and polyester polyols are difficult to meet the 3‰ standard of ethyl maltol resistance. The performance of resistance to high-temperature steaming and boiling also needs to be further improved, and the stability of the product's use also needs to be further optimized. Summary of the invention

[0004] In order to improve the resistance of coating adhesive to ethyl maltol and edible oil media under high-temperature cooking environment, the present invention provides a medium-resistant polyol and its preparation method and application. The medium-resistant polyol is applied to the two-component solvent-free food aluminum foil flexible packaging coating adhesive. After packaging the food containing ethyl maltol, under high-temperature cooking conditions, its resistance to ethyl maltol and edible oil media is outstanding.

[0005] The technical solution provided by the present invention is specifically as follows:

[0006] In a first aspect, the present invention provides a medium-resistant polyol having a structure shown in Formula I or II:

[0007]

[0008] In a second aspect, the present invention provides a method for preparing a medium-resistant polyol, comprising the following steps:

[0009] The dibasic acid, the dimer acid and the first diol are subjected to an esterification reaction to generate a first polyester polyol having an acid value of 79 to 89 mg KOH / g;

[0010] reacting the first polyester polyol with a diamine to generate a second polyester polyol having an amine value of 136 to 154 mg KOH / g;

[0011] The second polyester polyol is prepolymerized with the diisocyanate containing a cyclic structure, and the second diol is used for end-capping, and the reaction is carried out until the NCO content is less than 0.3% to obtain a medium-resistant polyol.

[0012] In combination with the second aspect of the present invention, in some embodiments, the dibasic acid is one or more of adipic acid, sebacic acid, phthalic acid, phthalic anhydride, isophthalic acid, and 2-methyl-1,3-propanedioic acid; and / or, the first diol is one or more of ethylene glycol, diethylene glycol, 2-methyl-1,3-propanediol, dipropylene glycol, and neopentyl glycol; and / or, the second diol is one or more of ethylene glycol, diethylene glycol, 2-methyl-1,3-propanediol, and dipropylene glycol; and / or, the diamine is hexamethylenediamine and / or isophoronediamine; and / or, the diisocyanate containing a cyclic structure is isophorone diisocyanate.

[0013] In conjunction with the second aspect of the present invention, in some embodiments, the amount of the dibasic acid is 650-710 parts by mass; and / or, the dibasic acid is composed of 400-438 parts by mass of adipic acid and 250-270 parts by mass of 2-methyl-1,3-propanedioic acid; and / or, the amount of the dimer acid is 560-705 parts by mass; and / or, the amount of the first diol is 104-127 parts by mass; and / or, the amount of the diamine is 160-260 parts by mass; and / or, the diamine is composed of hexamethylenediamine and isophoronediamine in a weight ratio of (2-3):1; and / or, the amount of the diisocyanate containing a cyclic structure is 1000-1200 parts by mass; and / or, the amount of the second diol is 400-450 parts by mass.

[0014] In a third aspect, the present invention provides the use of the above-mentioned medium-resistant polyol in a two-component solvent-free food aluminum foil flexible packaging laminating adhesive.

[0015] In a fourth aspect, the present invention provides a two-component solvent-free food aluminum foil flexible packaging coating adhesive, the two-component solvent-free food aluminum foil flexible packaging coating adhesive is composed of component A and component B in a weight ratio of 100: (50-90), and the molar ratio of NCO to OH is 1.4-2.3; wherein:

[0016] Component A is a first prepolymer formed by reacting a medium-resistant polyol, a first polyether polyol and a diisocyanate;

[0017] Component B includes a medium-resistant polyol, a second polyether polyol, an epoxy resin, a silane coupling agent and a catalyst;

[0018] The media-resistant polyol is a media-resistant polyol having a structure shown in Formula I or II or a media-resistant polyol prepared by the preparation method of the above-mentioned media-resistant polyol.

[0019] In conjunction with the fourth aspect of the present invention, in some embodiments, component A is formed by reacting a medium-resistant polyol, a first polyether polyol, and a diisocyanate in a weight ratio of 55:45:135;

[0020] Component B is composed of a medium-resistant polyol, a second polyether polyol, an epoxy resin, a silane coupling agent and a catalyst in a weight ratio of 70:30:8:0.5:0.02;

[0021] In conjunction with the fourth aspect of the present invention, in some embodiments, the isocyanate is one or more of xylene diisocyanate, toluene diisocyanate, polymethyl polyphenyl polyisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate; and / or,

[0022] The first polyether polyol is one or more of 307, 210, and 220; and / or,

[0023] The epoxy resin is one or more of E51, E12, E44, and E128; and / or,

[0024] The silane coupling agent is one or more of KH560, KH-171, KH550, KH-172, and KH570; and / or,

[0025] The catalyst is one or more of dibutyltin cinnamate, DMDEE, and A33; and / or,

[0026] The second polyether polyol is one or more of 210, 220, and 304.

[0027] In a fifth aspect, the present invention provides application of a two-component solvent-free food aluminum foil flexible packaging laminating adhesive in the field of food flexible packaging.

[0028] In a sixth aspect, the present invention provides a food packaging bag sealed with the above-mentioned two-component solvent-free food aluminum foil flexible packaging laminating adhesive.

[0029] Compared with the prior art, the present invention has at least the following beneficial effects:

[0030] 1. After the medium-resistant polyol having the structure shown in Formula I or II provided by the present invention is added into the two-component solvent-free food aluminum foil flexible packaging coating adhesive, it has significant medium resistance.

[0031] 2. The two-component solvent-free food aluminum foil flexible packaging coating adhesive provided by the present invention exhibits significant resistance to ethyl maltol and edible oil media under high-temperature cooking conditions after curing; and it does not contain solvents, meets the requirements of environmental protection and transportation, reduces costs, reduces energy consumption, has high composite efficiency, and is easy to operate. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are 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.

[0033] For simplicity, the present invention only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an unambiguous range; and any lower limit can be combined with other lower limits to form an unambiguous range; similarly, any upper limit can be combined with any other upper limit to form an unambiguous range. In addition, although not explicitly stated, each point or single value between the endpoints of the range is included in the range. Thus, each point or single value can be combined with any other point or single value as its own lower limit or upper limit or with other lower limits or upper limits to form an unambiguous range.

[0034] It should be noted that, in the description of the present invention, unless otherwise specified, "above" and "below" are inclusive numbers, and the meaning of "multiple" in "one or more" is two or more. Relational terms such as "first" and "second" 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 the process, method, article or equipment 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 equipment. In the absence of further restrictions, the elements defined by the sentence "including one..." do not exclude the presence of other identical elements in the process, method, article or equipment including the elements.

[0035] In the description of the present invention, the description with reference to the terms "any embodiment / method", "one embodiment / method", "some embodiments / methods", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment / method or example are included in at least one embodiment / method or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment / method or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments / methods or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments / methods or examples described in this specification and the features of the different embodiments / methods or examples, without contradiction.

[0036] The above summary of the invention of the present invention is not intended to describe each disclosed embodiment or each implementation in the present invention. The following description more specifically illustrates exemplary embodiments. These embodiments can be used in various combinations. In each example, the enumeration is only used as a representative group and should not be interpreted as exhaustive.

[0037] Media-resistant polyols:

[0038] The medium-resistant polyol provided by the present invention has a structure shown in Formula I or II:

[0039]

[0040] The medium-resistant polyol provided by the present invention contains a medium-resistant aliphatic long chain segment as the main chain, and contains a side group structure that is stable to high-temperature steaming and boiling media, such as an amide group, a polyurea group, and a cyclic structure. These structures give it excellent wettability with the surface of the film substrate. In addition, these groups also enhance the bonding strength with the aluminum foil, show excellent tolerance to the medium under high temperature environment, effectively protect the interface between the aluminum foil and the surface of the plastic film from damage, thereby improving the overall performance of the packaging bag.

[0041] First, the medium-resistant polyol contains aliphatic acids such as adipic acid and dimer acid. Compared with polyols containing aromatic acids, it exhibits superior high-temperature hydrolysis resistance, acid hydrolysis resistance, and oil and fat damage resistance, thereby effectively protecting the interfacial bonding performance between the adhesive and the aluminum foil. Secondly, the hydrophobic alcohols contained in the medium-resistant polyol, such as 2-methyl-1,3-propanedioic acid and neopentyl glycol, have multiple side group structures that reduce the water absorption of the adhesive. The long-chain dimer acid, 2-methyl-1,3-propanedioic acid and neopentyl glycol, as well as the flexible bio-based long-chain structure, enhance the solubility between the adhesives and make the microstructure of the adhesive more compact. The side group structure also improves the wetting performance of the adhesive and the membrane surface, thereby enhancing the bonding strength and reducing the damage of high-temperature media. Third, the medium-resistant polyol contains a polyurea polyol structure, which not only has strong bonding properties and high temperature resistance, especially for rigid aluminum foil structures, but also has extremely strong hydrophobic properties and high temperature medium resistance. Fourth, the amide structure in the medium-resistant polyol can effectively prevent high-temperature ethyl maltol and grease from penetrating the film material to damage the adhesive and the aluminum foil surface. The amide structure also has the advantage of stable chemical properties and is not easily damaged by chemical media, ensuring the stability of the medium resistance of the adhesive after curing. Finally, the epoxy group and silane structure contained in the medium-resistant polyol increase the bonding strength of the laminating adhesive, especially for aluminum foil structures. It has high mechanical strength and heat resistance. When the adhesive is damaged by the medium, the epoxy group can undergo a secondary reaction to further increase the molecular weight of the adhesive, effectively preventing the damage to the film caused by 121°C cooking, and achieving the effect of high-temperature cooking and medium resistance of the packaging bag. This solves the problems of solvent-free polyurethane composite food packaging in resistance to ethyl maltol, attenuation of steaming and boiling strength, and delamination of composite films. In particular, it solves the damage of 3‰ or more ethyl maltol and oil to the film and aluminum foil during the aging process of food packaging after high-temperature steaming, ensuring that the composite structure will not age and delaminate to destroy the air barrier and water barrier properties of the packaging bag, thereby protecting the shelf life of the food.

[0042] Preparation method of medium-resistant polyol:

[0043] The method for preparing a medium-resistant polyol provided by the present invention comprises the following steps:

[0044] The dibasic acid, the dimer acid and the first diol are subjected to an esterification reaction to generate a first polyester polyol having an acid value of 79 to 89 mg KOH / g;

[0045] reacting the first polyester polyol with a diamine to generate a second polyester polyol having an amine value of 136 to 154 mg KOH / g;

[0046] The second polyester polyol is prepolymerized with the diisocyanate containing a cyclic structure, and the second diol is used for end-capping, and the reaction is carried out until the NCO content is less than 0.3% to obtain a medium-resistant polyol.

[0047] The preparation method firstly causes a dibasic acid, a dimer acid and a first diol to undergo an esterification reaction to obtain a medium-resistant aliphatic long chain segment as a main chain; then causes a first polyester polyol to react with a diamine to connect an amide group to the main chain; and finally causes a second polyester polyol to undergo a prepolymerization reaction with a diisocyanate containing a cyclic structure to obtain a polyurea group and a cyclic structure.

[0048] In some embodiments, the dibasic acid is one or more of adipic acid, sebacic acid, phthalic acid, phthalic anhydride, isophthalic acid, and 2-methyl-1,3-propanedioic acid; and / or, the first diol is one or more of ethylene glycol, diethylene glycol, 2-methyl-1,3-propanediol, dipropylene glycol, and neopentyl glycol; and / or, the second diol is one or more of ethylene glycol, diethylene glycol, 2-methyl-1,3-propanediol, and dipropylene glycol; and / or, the diamine is hexamethylenediamine and / or isophoronediamine; and / or, the diisocyanate containing a cyclic structure is isophorone diisocyanate.

[0049] In some embodiments, the dibasic acid is used in an amount of 650 to 710 parts by mass; and / or, the dibasic acid is composed of 400 to 438 parts by mass of adipic acid and 250 to 270 parts by mass of 2-methyl-1,3-propanedioic acid; and / or, the dimer acid is used in an amount of 560 to 705 parts by mass; and / or, the first diol is used in an amount of 104 to 127 parts by mass; and / or, the diamine is used in an amount of 160 to 260 parts by mass; and / or, the diamine is composed of hexamethylenediamine and isophoronediamine in a weight ratio of (2 to 3):1; and / or, the diisocyanate containing a cyclic structure is used in an amount of 1000 to 1200 parts by mass; and / or, the second diol is used in an amount of 400 to 450 parts by mass.

[0050] application:

[0051] The two-component solvent-free food aluminum foil flexible packaging coating adhesive prepared by the present invention using the above-mentioned medium-resistant polyol as the main component is a universal adhesive with high peel strength, fast curing, and meeting the medium resistance performance required for boiling and steaming. In particular, it solves the problem that the solvent-free two-component polyurethane adhesive cannot withstand high-temperature cooking and aging stratification of 3‰ or more ethyl maltol, and has a very high market value.

[0052] The two-component solvent-free food aluminum foil flexible packaging film adhesive provided by the present invention is composed of component A and component B in a weight ratio of 100:(50-90), and the molar ratio of NCO to OH is 1.4-2.3; wherein:

[0053] Component A is a first prepolymer formed by reacting a medium-resistant polyol, a first polyether polyol and a diisocyanate;

[0054] Component B includes a medium-resistant polyol, a second polyether polyol, an epoxy resin, a silane coupling agent and a catalyst;

[0055] The media-resistant polyol is a media-resistant polyol having a structure shown in Formula I or II or a media-resistant polyol prepared by the preparation method of the above-mentioned media-resistant polyol.

[0056] The two-component solvent-free food aluminum foil flexible packaging coating adhesive provided by the present invention has low viscosity, contains multiple side groups and a relatively long main chain structure, can effectively reduce the surface energy of the film surface, has strong wettability, and avoids the generation of white spots on the packaging surface; the amide bonds contained in the coating adhesive can effectively prevent edible oil and ethyl maltol from damaging the adhesive film, and the epoxy groups and carbamate groups contained in the coating adhesive increase the bonding strength of the coating adhesive, especially for the aluminum foil structure, it has high mechanical strength and heat resistance, can prevent the adhesive film from being damaged by cooking at 121°C, and achieves the effect of packaging bags being resistant to cooking and media, and solves the problems of food packaging bags being resistant to ethyl maltol, strength attenuation during cooking and boiling, and composite film delamination.

[0057] In some embodiments, the first prepolymer is prepared by the following method: mixing a medium-resistant polyol and a first polyether polyol, vacuum dehydrating at 100±5°C, then cooling to 80±5°C, adding diisocyanate, and completing the reaction to obtain a first prepolymer.

[0058] In some embodiments, component A is formed by reacting a medium-resistant polyol, a first polyether polyol and a diisocyanate in a weight ratio of 55:45:135; component B is composed of a medium-resistant polyol, a second polyether polyol, an epoxy resin, a silane coupling agent and a catalyst in a weight ratio of 70:30:8:0.5:0.02. The above is only an embodiment of the present invention and should not be regarded as limiting the amount of each component in the two-component solvent-free food aluminum foil flexible packaging film adhesive provided by the present invention. Those skilled in the art can make reasonable adjustments on this basis.

[0059] In some embodiments, the isocyanate is one or more of xylene diisocyanate, toluene diisocyanate, polymethyl polyphenyl polyisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate; and / or the first polyether polyol is one or more of 307, 210, and 220; and / or the epoxy resin is one or more of E51, E12, E44, and E128; and / or the silane coupling agent is one or more of KH560, KH-171, KH550, KH-172, and KH570; and / or the catalyst is one or more of dibutyltin cinnamate, DMDEE, and A33; and / or the second polyether polyol is one or more of 210, 220, and 304.

[0060] The method for sealing a food packaging bag using the above-mentioned two-component solvent-free food aluminum foil flexible packaging laminating adhesive comprises the following steps: preheating component A and component B respectively, and then mixing component A and component B at a mass ratio of A:B=100:(50-90) at a low speed to obtain a premixed adhesive; applying the premixed adhesive on the surface of the bag material, and curing at 40-60°C for 48-72 hours.

[0061] Example:

[0062] The technical solution provided by the present invention is described in detail below in conjunction with embodiments.

[0063] Unless otherwise specified, the medium-resistant polyol, component A, and component B used in the examples and comparative examples are prepared as follows:

[0064] The method for preparing a medium-resistant polyol comprises the following steps:

[0065] Step 1: 400-438 parts by weight of adipic acid, 560-705 parts by weight of dimer acid, 250-270 parts by weight of 2-methyl-1,3-propanedioic acid, 104-127 parts by weight of neopentyl glycol, 30-100 ppm of a catalyst, and 30-100 ppm of an antioxidant are heated to 220° C. to react and prepare a first polyester polyol having an acid value of 79-89 mgKOH / g; wherein the optional parts by weight of adipic acid are 400, 405, 409, 414, 419, 422, 426, 429 , 431, 435, 438; the optional mass parts of dimer acid are 705, 686, 670, 651, 632, 621, 605, 594, 586, 571, 560; the optional mass parts of 2-methyl-1,3-propanedioic acid are 250, 253, 255, 258, 260, 262, 264, 266, 267, 268, 270; the optional mass parts of neopentyl glycol are 127, 124, 121, 118, 115, 113, 111, 109, 107, 106, 104.

[0066] Step 2: Add 182 parts by mass of hexamethylenediamine and 73 parts by mass of isophoronediamine to the first polyester polyol, continue to react at 220°C until the amine value is 136-154 mgKOH / g and the moisture is less than 500 ppm, cool to 60-100°C, add 1110 parts by mass of isophorone diisocyanate and 424 parts by mass of diethylene glycol, react until NCO is less than 0.3%, and obtain a medium-resistant polyol.

[0067] The preparation method of component B of the two-component solvent-free food aluminum foil flexible packaging laminating adhesive is as follows: 70 parts of medium-resistant polyol, 30 parts of polyether polyol, 0.5 parts of silane coupling agent, 8 parts of epoxy resin and 0.02 parts of catalyst are uniformly mixed according to the mass parts shown in Table 2.

[0068] Preparation method of component A of two-component solvent-free food aluminum foil flexible packaging laminating adhesive: add medium-resistant polyol and polyether polyol into a reaction kettle according to the mass parts shown in Table 2, vacuum dehydrate at 100°C for 1 hour, then cool to 80°C, add isocyanate, react for 5 hours, and obtain component A.

[0069] Example 1

[0070] The method for preparing the medium-resistant polyol provided in this embodiment comprises the following steps:

[0071] Step 1: 400 parts by mass of adipic acid, 705 parts by mass of dimer acid, 250 parts by mass of 2-methyl-1,3-propanedioic acid, 127 parts by mass of neopentyl glycol, 30 ppm of catalyst tetrabutyl titanate, and 30 ppm of antioxidant 1010 are heated to 220° C. to react and prepare a first polyester polyol having an acid value of 81 mgKOH / g;

[0072] Step 2: Add 182 parts by mass of hexamethylenediamine and 73 parts by mass of isophoronediamine to the first polyester polyol, continue to react at 220°C until the amine value is 140.6 mgKOH / g and the moisture is <500 ppm, cool to 80°C, add 1110 parts by mass of isophorone diisocyanate and 424 parts by mass of diethylene glycol, react until NCO is less than 0.3%, and obtain a medium-resistant polyol.

[0073] test:

[0074] According to the formula of component A and component B of the two-component solvent-free food aluminum foil flexible packaging laminating adhesive in Table 1, they were mixed according to A:B=100:80 (mass ratio), and the PET / Al / RCPP three-layer film structure was laminated and cured in an oven at 50°C for 60 hours. The 90° peel strength test was performed, and the test performance results were shown in Table 2, as well as the cooking at 121°C, 121°C with 3‰ ethyl maltol aqueous solution, small fish, and popcorn chicken.

[0075] Example 2

[0076] The method for preparing the medium-resistant polyol provided in this embodiment comprises the following steps:

[0077] Step 1: 405 parts by mass of adipic acid, 686 parts by mass of dimer acid, 253 parts by mass of 2-methyl-1,3-propanedioic acid, 124 parts by mass of neopentyl glycol, 35 ppm of catalyst tetrabutyl titanate, and 35 ppm of antioxidant 1010 are heated to 220° C. to react and prepare a first polyester polyol having an acid value of 82 mgKOH / g;

[0078] Step 2: Add 182 parts by mass of hexamethylenediamine and 73 parts by mass of isophoronediamine to the first polyester polyol, continue to react at 220°C until the amine value is 142.3 mgKOH / g and the moisture is <500 ppm, cool to 80°C, add 1110 parts by mass of isophorone diisocyanate and 424 parts by mass of diethylene glycol, react until NCO is less than 0.3%, and obtain a medium-resistant polyol.

[0079] test:

[0080] According to the formula of component A and component B of the two-component solvent-free food aluminum foil flexible packaging laminating adhesive in Table 1, they were mixed according to A:B=100:80 (mass ratio), and the PET / Al / RCPP three-layer film structure was laminated and cured in an oven at 50°C for 60 hours. The 90° peel strength test was performed, and the test performance results were shown in Table 2, as well as the cooking at 121°C, 121°C with 3‰ ethyl maltol aqueous solution, small fish, and popcorn chicken.

[0081] Example 3

[0082] The method for preparing the medium-resistant polyol provided in this embodiment comprises the following steps:

[0083] Step 1: 409 parts by mass of adipic acid, 670 parts by mass of dimer acid, 255 parts by mass of 2-methyl-1,3-propanedioic acid, 121 parts by mass of neopentyl glycol, 40 ppm of catalyst tetrabutyl titanate, and 40 ppm of antioxidant 1010 are heated to 220° C. to react and prepare a first polyester polyol having an acid value of 83 mgKOH / g;

[0084] Step 2: Add 182 parts by mass of hexamethylenediamine and 73 parts by mass of isophoronediamine to the first polyester polyol, continue to react at 220°C until the amine value is 143.8 mgKOH / g and the moisture is <500 ppm, cool to 80°C, add 1110 parts by mass of isophorone diisocyanate and 424 parts by mass of diethylene glycol, react until NCO is less than 0.3%, and obtain a medium-resistant polyol.

[0085] test:

[0086] According to the formula of component A and component B of the two-component solvent-free food aluminum foil flexible packaging laminating adhesive in Table 1, they were mixed according to A:B=100:80 (mass ratio), and the PET / Al / RCPP three-layer film structure was laminated and cured in an oven at 50°C for 60 hours. The 90° peel strength test was performed, and the test performance results were shown in Table 2, as well as the cooking at 121°C, 121°C with 3‰ ethyl maltol aqueous solution, small fish, and popcorn chicken.

[0087] Example 4

[0088] The method for preparing the medium-resistant polyol provided in this embodiment comprises the following steps:

[0089] Step 1: 414 parts by mass of adipic acid, 651 parts by mass of dimer acid, 258 parts by mass of 2-methyl-1,3-propanedioic acid, 118 parts by mass of neopentyl glycol, 45 ppm of catalyst tetrabutyl titanate, and 45 ppm of antioxidant 1010 are heated to 220° C. to react and prepare a first polyester polyol having an acid value of 84 mgKOH / g;

[0090] Step 2: Add 182 parts by mass of hexamethylenediamine and 73 parts by mass of isophoronediamine to the first polyester polyol, continue to react at 220°C until the amine value is 145.6 mgKOH / g and the moisture is <500 ppm, cool to 80°C, add 1110 parts by mass of isophorone diisocyanate and 424 parts by mass of diethylene glycol, react until NCO is less than 0.3%, and obtain a medium-resistant polyol.

[0091] test:

[0092] According to the formula of component A and component B of the two-component solvent-free food aluminum foil flexible packaging laminating adhesive in Table 1, they were mixed according to A:B=100:80 (mass ratio), and the PET / Al / RCPP three-layer film structure was laminated and cured in an oven at 50°C for 60 hours. The 90° peel strength test was performed, and the test performance results were shown in Table 2, as well as the cooking at 121°C, 121°C with 3‰ ethyl maltol aqueous solution, small fish, and popcorn chicken.

[0093] Example 5

[0094] The method for preparing the medium-resistant polyol provided in this embodiment comprises the following steps:

[0095] Step 1: 419 parts by mass of adipic acid, 632 parts by mass of dimer acid, 260 parts by mass of 2-methyl-1,3-propanedioic acid, 115 parts by mass of neopentyl glycol, 50 ppm of catalyst tetrabutyl titanate, and 50 ppm of antioxidant 1010 are heated to 220° C. to react and prepare a first polyester polyol having an acid value of 85 mgKOH / g;

[0096] Step 2: Add 182 parts by mass of hexamethylenediamine and 73 parts by mass of isophoronediamine to the first polyester polyol, continue to react at 220°C until the amine value is 147.4 mgKOH / g and the moisture is <500 ppm, cool to 80°C, add 1110 parts by mass of isophorone diisocyanate and 424 parts by mass of diethylene glycol, react until NCO is less than 0.3%, and obtain a medium-resistant polyol.

[0097] test:

[0098] According to the formula of component A and component B of the two-component solvent-free food aluminum foil flexible packaging laminating adhesive in Table 1, they were mixed according to A:B=100:80 (mass ratio), and the PET / Al / RCPP three-layer film structure was laminated and cured in an oven at 50°C for 60 hours. The 90° peel strength test was performed, and the test performance results were shown in Table 2, as well as the cooking at 121°C, 121°C with 3‰ ethyl maltol aqueous solution, small fish, and popcorn chicken.

[0099] Example 6

[0100] The method for preparing the medium-resistant polyol provided in this embodiment comprises the following steps:

[0101] Step 1: 422 parts by mass of adipic acid, 621 parts by mass of dimer acid, 262 parts by mass of 2-methyl-1,3-propanedioic acid, 113 parts by mass of neopentyl glycol, 55 ppm of catalyst tetrabutyl titanate, and 55 ppm of antioxidant 1010 are heated to 220° C. to react and prepare a first polyester polyol having an acid value of 85.7 mgKOH / g;

[0102] Step 2: Add 182 parts by mass of hexamethylenediamine and 73 parts by mass of isophoronediamine to the first polyester polyol, continue to react at 220°C until the amine value is 148.4 mgKOH / g and the moisture is <500 ppm, cool to 80°C, add 1110 parts by mass of isophorone diisocyanate and 424 parts by mass of diethylene glycol, react until NCO is less than 0.3%, and obtain a medium-resistant polyol.

[0103] test:

[0104] According to the formula of component A and component B of the two-component solvent-free food aluminum foil flexible packaging laminating adhesive in Table 1, they were mixed according to A:B=100:80 (mass ratio), and the PET / Al / RCPP three-layer film structure was laminated and cured in an oven at 50°C for 60 hours. The 90° peel strength test was performed, and the test performance results were shown in Table 2, as well as the cooking at 121°C, 121°C with 3‰ ethyl maltol aqueous solution, small fish, and popcorn chicken.

[0105] Example 7

[0106] The method for preparing the medium-resistant polyol provided in this embodiment comprises the following steps:

[0107] Step 1: 426 parts by mass of adipic acid, 605 parts by mass of dimer acid, 264 parts by mass of 2-methyl-1,3-propanedioic acid, 111 parts by mass of neopentyl glycol, 60 ppm of catalyst tetrabutyl titanate, and 60 ppm of antioxidant 1010 are heated to 220° C. to react and prepare a first polyester polyol having an acid value of 79 mgKOH / g;

[0108] Step 2: Add 182 parts by mass of hexamethylenediamine and 73 parts by mass of isophoronediamine to the first polyester polyol, continue to react at 220°C until the amine value is 136 mgKOH / g and the moisture is <500 ppm, cool to 80°C, add 1110 parts by mass of isophorone diisocyanate and 424 parts by mass of diethylene glycol, react until NCO is less than 0.3%, and obtain a medium-resistant polyol.

[0109] test:

[0110] According to the formula of component A and component B of the two-component solvent-free food aluminum foil flexible packaging laminating adhesive in Table 1, they were mixed according to A:B=100:80 (mass ratio), and the PET / Al / RCPP three-layer film structure was laminated and cured in an oven at 50°C for 60 hours. The 90° peel strength test was performed, and the test performance results were shown in Table 2, as well as the cooking at 121°C, 121°C with 3‰ ethyl maltol aqueous solution, small fish, and popcorn chicken.

[0111] Example 8

[0112] The method for preparing the medium-resistant polyol provided in this embodiment comprises the following steps:

[0113] Step 1: 429 parts by mass of adipic acid, 594 parts by mass of dimer acid, 266 parts by mass of 2-methyl-1,3-propanedioic acid, 109 parts by mass of neopentyl glycol, 70 ppm of catalyst tetrabutyl titanate, and 70 ppm of antioxidant 1010 are heated to 220° C. to react and prepare a first polyester polyol having an acid value of 79.5 mgKOH / g;

[0114] Step 2: Add 182 parts by mass of hexamethylenediamine and 73 parts by mass of isophoronediamine to the first polyester polyol, continue to react at 220°C until the amine value is 137.6 mgKOH / g and the moisture is <500 ppm, cool to 80°C, add 1110 parts by mass of isophorone diisocyanate and 424 parts by mass of diethylene glycol, react until NCO is less than 0.3%, and obtain a medium-resistant polyol.

[0115] test:

[0116] According to the formula of component A and component B of the two-component solvent-free food aluminum foil flexible packaging laminating adhesive in Table 1, they were mixed according to A:B=100:80 (mass ratio), and the PET / Al / RCPP three-layer film structure was laminated and cured in an oven at 50°C for 60 hours. The 90° peel strength test was performed, and the test performance results were shown in Table 2, as well as the cooking at 121°C, 121°C with 3‰ ethyl maltol aqueous solution, small fish, and popcorn chicken.

[0117] Example 9

[0118] The method for preparing the medium-resistant polyol provided in this embodiment comprises the following steps:

[0119] Step 1: 431 parts by mass of adipic acid, 586 parts by mass of dimer acid, 267 parts by mass of 2-methyl-1,3-propanedioic acid, 107 parts by mass of neopentyl glycol, 80 ppm of catalyst tetrabutyl titanate, and 80 ppm of antioxidant 1010 are heated to 220° C. to react and prepare a first polyester polyol having an acid value of 80 mgKOH / g;

[0120] Step 2: Add 182 parts by mass of hexamethylenediamine and 73 parts by mass of isophoronediamine to the first polyester polyol, continue to react at 220°C until the amine value is 138.5 mgKOH / g and the moisture is <500 ppm, cool to 80°C, add 1110 parts by mass of isophorone diisocyanate and 424 parts by mass of diethylene glycol, react until NCO is less than 0.3%, and obtain a medium-resistant polyol.

[0121] test:

[0122] According to the formula of component A and component B of the two-component solvent-free food aluminum foil flexible packaging laminating adhesive in Table 1, they were mixed according to A:B=100:80 (mass ratio), and the PET / Al / RCPP three-layer film structure was laminated and cured in an oven at 50°C for 60 hours. The 90° peel strength test was performed, and the test performance results were shown in Table 2, as well as the cooking at 121°C, 121°C with 3‰ ethyl maltol aqueous solution, small fish, and popcorn chicken.

[0123] Example 10

[0124] The method for preparing the medium-resistant polyol provided in this embodiment comprises the following steps:

[0125] Step 1: 435 parts by mass of adipic acid, 571 parts by mass of dimer acid, 268 parts by mass of 2-methyl-1,3-propanedioic acid, 106 parts by mass of neopentyl glycol, 90 ppm of catalyst tetrabutyl titanate, and 90 ppm of antioxidant 1010 are heated to 220° C. to react and prepare a first polyester polyol having an acid value of 80.8 mgKOH / g;

[0126] Step 2: Add 182 parts by mass of hexamethylenediamine and 73 parts by mass of isophoronediamine to the first polyester polyol, continue to react at 220°C until the amine value is 139.9 mgKOH / g and the moisture is <500 ppm, cool to 80°C, add 1110 parts by mass of isophorone diisocyanate and 424 parts by mass of diethylene glycol, react until NCO is less than 0.3%, and obtain a medium-resistant polyol.

[0127] test:

[0128] According to the formula of component A and component B of the two-component solvent-free food aluminum foil flexible packaging laminating adhesive in Table 1, they were mixed according to A:B=100:80 (mass ratio), and the PET / Al / RCPP three-layer film structure was laminated and cured in an oven at 50°C for 60 hours. The 90° peel strength test was performed, and the test performance results were shown in Table 2, as well as the cooking at 121°C, 121°C with 3‰ ethyl maltol aqueous solution, small fish, and popcorn chicken.

[0129] Embodiment 11

[0130] The method for preparing the medium-resistant polyol provided in this embodiment comprises the following steps:

[0131] Step 1: 438 parts by mass of adipic acid, 560 parts by mass of dimer acid, 270 parts by mass of 2-methyl-1,3-propanedioic acid, 104 parts by mass of neopentyl glycol, 100 ppm of catalyst tetrabutyl titanate, and 100 ppm of antioxidant 1010 are heated to 220° C. to react and prepare a first polyester polyol having an acid value of 89 mgKOH / g;

[0132] Step 2: Add 182 parts by mass of hexamethylenediamine and 73 parts by mass of isophoronediamine to the first polyester polyol, continue to react at 220°C until the amine value is 154 mgKOH / g and the moisture content is <500 ppm, cool to 80°C, add 1110 parts by mass of isophorone diisocyanate and 424 parts by mass of diethylene glycol, react until the NCO content is less than 0.3%, and obtain a medium-resistant polyol.

[0133] test:

[0134] According to the formula of component A and component B of the two-component solvent-free food aluminum foil flexible packaging laminating adhesive in Table 1, they were mixed according to A:B=100:80 (mass ratio), and the PET / Al / RCPP three-layer film structure was laminated and cured in an oven at 50°C for 60 hours. The 90° peel strength test was performed, and the test performance results were shown in Table 2, as well as the cooking at 121°C, 121°C with 3‰ ethyl maltol aqueous solution, small fish, and popcorn chicken.

[0135] Table 1 Formula of component A and component B of two-component solvent-free food aluminum foil flexible packaging laminating adhesive (parts by mass)

[0136] Flexible packaging film adhesive Component A Component B Xylene diisocyanate 135 Media resistant polyols 55 70 210 45 307 30 KH560 0.5 E128 8 DMDEE 0.02

[0137] Table 2 PET / Al / RCPP three-layer film structure coating performance (test method refers to national standards)

[0138]

[0139] The test shows that the two-component solvent-free food aluminum foil flexible packaging film adhesive prepared with medium-resistant polyol has high peel strength and high strength after cooking. It has good resistance to 3‰ and above ethyl maltol, small fish, and chicken popcorn. In particular, it can withstand the cooking of chicken popcorn, and will not delaminate after aging. It can withstand the erosion of 3‰ and above ethyl maltol and chicken popcorn. The performance meets the national standard and will not delaminate after aging. The general solvent-free polyester and polyether adhesives are a big problem in these two media, and the performance is difficult to meet. It is a universal high-strength two-component solvent-free food aluminum foil flexible packaging film adhesive.

[0140] The foregoing is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A medium-resistant polyol, characterized in that: Having the structure shown in formula I or II:

2. A method for preparing a medium-resistant polyol, characterized in that: The steps include: The dibasic acid, the dimer acid and the first diol are subjected to an esterification reaction to generate a first polyester polyol having an acid value of 79 to 89 mg KOH / g; reacting the first polyester polyol with a diamine to generate a second polyester polyol having an amine value of 136 to 154 mg KOH / g; The second polyester polyol is prepolymerized with the diisocyanate containing a cyclic structure, and the second diol is used for end-capping, and the reaction is carried out until the NCO content is less than 0.3% to obtain a medium-resistant polyol.

3. The method for preparing a medium-resistant polyol according to claim 2, characterized in that: The dibasic acid is one or more of adipic acid, sebacic acid, phthalic acid, phthalic anhydride, isophthalic acid, and 2-methyl-1,3-propanedioic acid; and / or, The first diol is one or more of ethylene glycol, diethylene glycol, 2-methyl-1,3-propanediol, dipropylene glycol, and neopentyl glycol; and / or, The second diol is one or more of ethylene glycol, diethylene glycol, 2-methyl-1,3-propanediol, and dipropylene glycol; and / or, The diamine is hexamethylenediamine and / or isophoronediamine; and / or, The diisocyanate containing a cyclic structure is isophorone diisocyanate.

4. The method for preparing a medium-resistant polyol according to claim 2, characterized in that: The dibasic acid is used in an amount of 650 to 710 parts by mass; and / or, The dibasic acid is composed of 400 to 438 parts by mass of adipic acid and 250 to 270 parts by mass of 2-methyl-1,3-propanedioic acid; and / or, The dimer acid is used in an amount of 560 to 705 parts by weight; and / or, The amount of the first diol is 104 to 127 parts by mass; and / or, The diamine is used in an amount of 160 to 260 parts by mass; and / or, The diamine is composed of hexamethylenediamine and isophoronediamine in a weight ratio of (2-3):1; and / or, The amount of the diisocyanate containing a cyclic structure is 1000 to 1200 parts by mass; and / or, The second diol is used in an amount of 400 to 450 parts by weight.

5. Use of the medium-resistant polyol described in claim 1 or the medium-resistant polyol prepared according to any one of claims 2 to 4 in a two-component solvent-free food aluminum foil flexible packaging laminating adhesive.

6. A two-component solvent-free food aluminum foil flexible packaging film adhesive, characterized in that: The two-component solvent-free food aluminum foil flexible packaging film adhesive is composed of component A and component B in a weight ratio of 100:(50-90), and the molar ratio of NCO to OH is 1.4-2.3; wherein: Component A is a first prepolymer formed by reacting a medium-resistant polyol, a first polyether polyol and a diisocyanate; Component B includes a medium-resistant polyol, a second polyether polyol, an epoxy resin, a silane coupling agent and a catalyst; The medium-resistant polyol is the medium-resistant polyol described in claim 1 or the medium-resistant polyol prepared according to any one of claims 2 to 4.

7. The two-component solvent-free food aluminum foil flexible packaging film-coating adhesive according to claim 6, characterized in that: Component A is formed by reacting a medium-resistant polyol, a first polyether polyol and a diisocyanate in a weight ratio of 55:45:135; Component B consists of a medium-resistant polyol, a second polyether polyol, an epoxy resin, a silane coupling agent and a catalyst in a weight ratio of 70:30:8:0.5:0.

02.

8. The two-component solvent-free food aluminum foil flexible packaging film-coating adhesive according to claim 6, characterized in that: The isocyanate is one or more of xylene diisocyanate, toluene diisocyanate, polymethyl polyphenyl polyisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate; and / or, The first polyether polyol is one or more of 307, 210, and 220; and / or, The epoxy resin is one or more of E51, E12, E44, and E128; and / or, The silane coupling agent is one or more of KH560, KH-171, KH550, KH-172, and KH570; and / or, The catalyst is one or more of dibutyltin cinnamate, DMDEE, and A33; and / or, The second polyether polyol is one or more of 210, 220, and 304.

9. Use of the two-component solvent-free food aluminum foil flexible packaging laminating adhesive according to any one of claims 6 to 8 in the field of food flexible packaging.

10. A food packaging bag sealed with the two-component solvent-free food aluminum foil flexible packaging laminating adhesive as claimed in any one of claims 6 to 8.

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