Medium-resistant reverse polyurethane laminating adhesive capable of being quickly cured at room temperature and preparation method of reverse polyurethane laminating adhesive

Abstract

The invention discloses a medium-resistant reverse polyurethane laminating adhesive capable of being quickly cured at room temperature and a preparation method of the medium-resistant reverse polyurethane laminating adhesive, and belongs to the field of laminating adhesive preparation, the laminating adhesive is prepared from a main agent and a curing agent according to the mass ratio of 20: (1.2-2), wherein the main agent is an ethyl acetate solution of NCO-terminated polyisocyanate resin prepared by reaction of polyester polyol, polymercaptan and isocyanate; the solid content of the main agent is 68-72 wt%, and the rotary viscosity of the main agent at 25 DEG C is 1000-2500 mPa.s; the curing agent is an ethyl acetate solution of polyether polyol, polycaprolactone polyol and a coupling agent, the solid content of the curing agent is 58-62 wt%, and the rotary viscosity of the curing agent at 25 DEG C is 10-100 mPa.s. The main agent and the curing agent of the laminating adhesive have high reaction speed after being mixed, and can ensure that the laminating adhesive is quickly cross-linked and cured at room temperature after being coated, thereby ensuring that the adhesive has high heat resistance and acid and alkali chemical medium resistance.

Description

Technical Field

[0001] The invention relates to the field of laminating adhesive preparation, in particular to a room temperature fast-solidifying medium-resistant reverse polyurethane laminating adhesive and a preparation method thereof. Background Art

[0002] In many regions of the international market, especially in tropical regions, daily chemical products such as softeners, hair dyes, shampoos, floor washes, detergents, kitchen washes, etc., have strong acid and alkali corrosion, and have higher requirements for the bonding and corrosion resistance of the corresponding flexible packaging laminating adhesives. On the other hand, the room temperature in tropical regions is usually above 35°C, so their traditional concepts and operating habits are that there is no curing room, which requires the laminating adhesive used to be able to cure quickly at a lower temperature to meet production and use needs.

[0003] At present, the conventional solvent-based flexible packaging laminating adhesive commonly used in China generally has a hydroxyl-terminated polyester or polyether polyol component as the main agent, and an NCO-terminated polyisocyanate component as the curing agent. This type of laminating adhesive can be called a positive adhesive. Although positive adhesive has advantages such as high initial adhesion, good heat resistance, long disc life, and low raw material cost, it also has some disadvantages, such as relatively high viscosity of the working fluid, slow speed, poor solvent release, high temperature aging, low tolerance for additives such as lubricants, poor acid and alkali resistance, etc., and cannot simultaneously meet the requirements of rapid curing at room temperature and resistance to chemical media.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The purpose of the present invention is to provide a room temperature fast-solidifying medium-resistant reverse polyurethane laminating adhesive and a preparation method thereof, wherein the main agent and the curing agent have a relatively high reaction speed after mixing, which can ensure that the laminating adhesive is quickly cross-linked and cured at room temperature after coating, thereby ensuring that the glue has relatively high heat resistance and acid and alkali chemical medium resistance, thereby solving the above-mentioned technical problems existing in the prior art.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] A room temperature fast-curing medium-resistant reverse polyurethane laminating adhesive, the laminating adhesive is composed of a main agent and a curing agent in a mass ratio of 20:1.2-2; wherein,

[0008] The main agent is an ethyl acetate solution of an NCO-terminated polyisocyanate resin prepared by reacting polyester polyol, polythiol and isocyanate; the solid content of the main agent is 68-72wt%, and the rotational viscosity at 25°C is 1000-2500mPa·s;

[0009] The curing agent is an ethyl acetate solution of polyether polyol, polycaprolactone polyol and a coupling agent, the solid content of the curing agent is 58-62wt%, and the rotational viscosity at 25°C is 10-100mPa·s.

[0010] Preferably, in the main agent of the above-mentioned laminating adhesive, the amount of each component in parts by mass is: 49-52 parts of polyester polyol, 18-21 parts of isocyanate, 1-3 parts of polythiol and 28-32 parts of ethyl acetate.

[0011] Preferably, in the main agent of the above-mentioned laminating adhesive, the hydroxyl value of the polyester polyol is 51-62 mgKOH / g, the acid value is less than 1.5 mgKOH / g, and the average molecular weight is 1800-2200. The polyester polyol is prepared from dibasic acid, diol, triol, antioxidant and catalyst.

[0012] Preferably, in the polyester polyol which is the main agent of the above-mentioned laminating adhesive, the amount of each component in parts by mass is: 20-25 parts of isophthalic acid, 21-25 parts of adipic acid, 18-22 parts of neopentyl glycol, 23-32 parts of diethylene glycol, 6-9 parts of trihydroxypropane, 0.02-0.06 parts of antioxidant and 0.01-0.04 parts of catalyst.

[0013] Preferably, in the above-mentioned laminating adhesive, the polyester polyol of the main agent is:

[0014] The catalyst is one or two of Guangzhou Yourun's AUCAT-ES01 and AUCAT-ES02 hydrolysis-resistant environmentally friendly titanium-containing metal catalysts;

[0015] The antioxidant is at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, triphenyl phosphite, and β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate.

[0016] Preferably, in the above-mentioned laminating adhesive, the polythiol in the main agent adopts the tetrafunctional polythiol 440HE of Blue Lobec;

[0017] The isocyanate in the main agent is one or two of 2,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate and isophorone diisocyanate.

[0018] Preferably, in the above-mentioned laminating adhesive, the amounts of the components in the curing agent are as follows by mass: 43-47 parts of polyether polyol, 16-22 parts of polycaprolactone polyol, 0.08-0.16 parts of silane coupling agent and 38-42 parts of ethyl acetate.

[0019] Preferably, in the curing agent of the above-mentioned laminating adhesive, the polyether polyol is one of MN-700, MN-1000, and DL-4000D of Shandong Bluestar Dongda;

[0020] The polycaprolactone polyol is one or two of PCL-2044, PCL-2053, PCL-3037, PCL-3057 and PCL-2200C produced by Hunan Juren;

[0021] The silane coupling agent is at least one of (3-aminopropyl)trimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidyloxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, and N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane.

[0022] A method for preparing the room temperature fast solid medium resistant reverse polyurethane laminating adhesive of the present invention comprises:

[0023] The main agent and curing agent are prepared separately, wherein:

[0024] Preparation of the main agent: taking various raw materials according to the formula of the room temperature fast solid medium-resistant reverse polyurethane laminating adhesive of the present invention, adding the polyester polyol and isocyanate in the raw materials into a reaction kettle and mixing them evenly, heating to 80-85° C. and reacting for 4-5 hours, then lowering the system temperature to 60° C., adding polythiol and ethyl acetate, and obtaining a product with a solid content of 68-72wt% and a rotational viscosity of 1000-2500mPa·s at 25° C., which is the main agent;

[0025] Preparation of curing agent: adding polyether polyol, polycaprolactone polyol, silane coupling agent and ethyl acetate in the raw materials into a reaction kettle and mixing them evenly to obtain a product with a solid content of 58-62wt% and a rotational viscosity of 10-100mPa·s at 25°C, which is the curing agent;

[0026] Preparation of laminating adhesive: The main agent and the curing agent are mixed evenly in a mass ratio of 20:1.2-2 to obtain the room temperature fast-curing medium-resistant reverse polyurethane laminating adhesive.

[0027] Preferably, in the above method, the polyester polyol in the main agent is a hydroxyl-terminated polyester polyol prepared by the following method through the synthesis of a carboxyl-terminated prepolymer and a hydroxyl-terminated reaction, including:

[0028] Step 11, synthesizing a carboxyl-terminated prepolymer: adding 20 to 25 parts of isophthalic acid, 21 to 25 parts of adipic acid, 18 to 21 parts of diethylene glycol, 0.02 to 0.06 parts of an antioxidant and 0.01 to 0.04 parts of a catalyst to a polyester synthesis reactor, wherein the acid is in excess of 40%, stepwise heating to 220 to 230° C., reacting for 6 to 8 hours until the acid value is measured to be stable and unchanged, to obtain a carboxyl-terminated prepolymer;

[0029] Step 12, hydroxyl-terminated reaction: After the above reaction is completed, 5 to 11 parts of diethylene glycol, 18 to 22 parts of neopentyl glycol and 6 to 9 parts of trimethylolpropane are continuously added to the above synthesis reactor for hydroxyl-terminated reaction, with an excess of 60% of alcohol, the starting temperature is set to 150°C, the temperature is increased by 10°C every 30 minutes, the temperature is increased stepwise and stirred until the material is melted, and then the temperature is kept at 200°C for 3 to 4 hours, and the synthesis reactor is evacuated, the reactor temperature is controlled at 235 to 245°C, and pre-evacuated at -0.02MPa, -0.04MPa, -0.06MPa, and -0.08MPa for 30 minutes respectively, and then a long vacuum operation is performed, the vacuum degree reaches -0.1MPa, and the long vacuum time is 1 to 2 hours, until the acid value of the product is less than 1.5mgKOH / g, and the hydroxyl value of the product reaches 51 to 62mgKOH / g, that is, the polyester polyol with terminal hydroxyl groups in the main agent is obtained.

[0030] Compared with the prior art, the room temperature fast solid medium resistant reverse polyurethane laminating adhesive and its preparation method provided by the present invention have the following beneficial effects:

[0031] By designing the adhesive system as a reverse two-component polyurethane system, that is, the main agent is a polyisocyanate resin with an NCO terminal, and the curing agent is a polyol resin with a hydroxyl terminal, the viscosity of the glue itself can be made relatively low, the solid content can be made relatively high, and it can be coated at a high concentration, saving application costs. At the same time, after the main agent / curing agent is mixed in the said proportion, it has a relatively high reaction speed, which can ensure that the laminating glue is rapidly cross-linked and cured at room temperature after coating, thereby ensuring that the glue has relatively high heat resistance and chemical resistance. In the synthesis of the main agent, the addition of a 4-official polythiol with a high degree of cross-linking can also extend the coating operation time, but it has a faster curing speed and strength, can replace traditional metal catalysts, meet the requirements of rapid curing at room temperature, and can be cut and bagged after 24 hours of composite aging, thereby improving production efficiency and meeting actual production operations and use requirements. DETAILED DESCRIPTION

[0032] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in combination with the specific content of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, not all of the embodiments, which does not constitute a limitation of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of the present invention.

[0033] First, the terms that may be used in this article are explained as follows:

[0034] The term “and / or” means that either or both of them can be realized at the same time. For example, X and / or Y means both “X” or “Y” and “X and Y”.

[0035] The terms "include", "comprises", "contains", "has" or other descriptions with similar semantics should be interpreted as non-exclusive inclusion. For example, including certain technical feature elements (such as raw materials, components, ingredients, carriers, dosage forms, materials, dimensions, parts, components, mechanisms, devices, steps, procedures, methods, reaction conditions, processing conditions, parameters, algorithms, signals, data, products or products, etc.) should be interpreted as including not only certain technical feature elements explicitly listed, but also other technical feature elements known in the art that are not explicitly listed.

[0036] The term "consisting of..." means excluding any technical feature elements not explicitly listed. If this term is used in a claim, it will make the claim closed, so that it does not contain technical feature elements other than the technical feature elements explicitly listed, except for the conventional impurities related to them. If this term only appears in a clause of a claim, it only limits the elements explicitly listed in the clause, and the elements recorded in other clauses are not excluded from the overall claim.

[0037] The term "parts by mass" refers to the mass ratio relationship between multiple components. For example, if it is described that component X is x parts by mass and component Y is y parts by mass, then the mass ratio of component X to component Y is x:y. 1 part by mass can represent any mass, for example, 1 part by mass can be represented as 1 kg or 3.1415926 kg. The sum of the parts by mass of all components is not necessarily 100 parts, but can be greater than 100 parts, less than 100 parts or equal to 100 parts. Unless otherwise specified, the parts, proportions and percentages described herein are all measured by mass.

[0038] When concentration, temperature, pressure, size or other parameters are expressed in the form of a numerical range, the numerical range should be understood to specifically disclose all ranges formed by the pairing of any upper limit, lower limit, and preferred value in the numerical range, regardless of whether the range is explicitly stated; for example, if a numerical range of "2 to 8" is stated, the numerical range should be interpreted as including ranges such as "2 to 7", "2 to 6", "5 to 7", "3 to 4 and 6 to 7", "3 to 5 and 7", "2 and 5 to 7", etc. Unless otherwise specified, the numerical ranges stated herein include both their end values ​​and all integers and fractions within the numerical range.

[0039] The scheme provided by the present invention is described in detail below. The contents not described in detail in the embodiments of the present invention belong to the prior art known to professionals in the field. If the specific conditions are not specified in the embodiments of the present invention, they are carried out according to the conventional conditions in the field or the conditions recommended by the manufacturer. If the manufacturers are not specified in the reagents or instruments used in the embodiments of the present invention, they are all conventional products that can be purchased commercially.

[0040] The embodiment of the present invention provides a room temperature fast-solidifying medium-resistant reverse polyurethane laminating adhesive, which is composed of a main agent and a curing agent, and the mass ratio of the main agent to the curing agent is 20:1.2-2.

[0041] The main agent is an ethyl acetate solution of an NCO-terminated polyisocyanate resin prepared by reacting polyester polyol with isocyanate; the mass of the ethyl acetate in the main agent is about 28-32wt%, and the rotational viscosity at 25°C is 1000-2500mPa·s;

[0042] The curing agent is an ethyl acetate solution of polyether polyol, polycaprolactone polyol and a coupling agent, the solid content of the curing agent is 58-62wt%, and the rotational viscosity at 25°C is 10-100mPa·s.

[0043] Preferably, in the above adhesive, the amounts of the components in the main agent are as follows: 49-52 parts by mass of polyester polyol, 18-21 parts by mass of isocyanate, 1-3 parts by mass of polythiol, and 28-32 parts by mass of ethyl acetate.

[0044] Preferably, in the above adhesive, the polyester polyol in the main agent has a hydroxyl value of 51-62 mgKOH / g, an acid value of <1.5 mgKOH / g, and an average molecular weight of 1800-2200. The polyester polyol is synthesized from dibasic acid, diol, triol, antioxidant and catalyst.

[0045] Preferably, in the above adhesive, the amounts of the components in the polyester polyol of the main agent are as follows by mass: 20-25 parts of isophthalic acid, 21-25 parts of adipic acid, 18-22 parts of neopentyl glycol, 23-32 parts of diethylene glycol, 6-9 parts of trihydroxypropane, 0.02-0.06 parts of antioxidant and 0.01-0.04 parts of catalyst.

[0046] The catalyst adopts one or two of Guangzhou Yourun's AUCAT-ES01 and AUCAT-ES02 hydrolysis-resistant environmentally friendly titanium metal catalysts. Compared with the organic titanium catalysts commonly used in polyester synthesis, this type of catalyst is perfectly compatible with the polyurethane system, stable and non-hydrolyzed, and has good high-temperature stability. It can maintain a long-term catalytic effect in the esterification reaction without the need for supplementation, thereby ensuring efficient and stable polyester synthesis;

[0047] The antioxidant is at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, triphenyl phosphite, and β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate.

[0048] Preferably, in the above adhesive, the isocyanate in the main agent is one or two of 2,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, and isophorone diisocyanate.

[0049] Preferably, in the above adhesive, the polythiol in the main agent is Blue Lobec's tetrafunctional polythiol 440HE.

[0050] Preferably, in the above adhesive, the amounts of the components in the curing agent are as follows: 43-47 parts by mass of polyether polyol, 16-22 parts by mass of polycaprolactone polyol, 0.08-0.16 parts by mass of silane coupling agent, and 38-42 parts by mass of ethyl acetate.

[0051] The polyether polyol is one of MN-700, MN-1000 and DL-4000D produced by Shandong Bluestar Dongda.

[0052] The polycaprolactone polyol is one or two of PCL-2044, PCL-2053, PCL-3037, PCL-3057 and PCL-2200C produced by Hunan Juren.

[0053] The silane coupling agent is at least one of (3-aminopropyl)trimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidyloxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, and N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane.

[0054] The embodiment of the present invention further provides a method for preparing the above-mentioned room temperature fast-curing medium-resistant reverse polyurethane laminating adhesive, comprising:

[0055] ① Preparation of the main agent: 49-52 parts by weight of the above polyester polyol and 18-21 parts by weight of isocyanate are added to a reaction kettle and mixed evenly, the temperature is raised to 80-85° C. for reaction for 4-5 hours, and then the system temperature is lowered to 60° C., 1-3 parts by weight of polythiol and 28-32 parts by weight of ethyl acetate are added to obtain a main agent having a solid content of 68-72 wt % and a rotational viscosity of 1000-2500 mPa·s at 25° C.;

[0056] ② Preparation of curing agent: 43-47 parts by weight of the above-mentioned polyether polyol, 16-22 parts by weight of polycaprolactone polyol, 0.08-0.16 parts by weight of silane coupling agent, and 38-42 parts by weight of ethyl acetate are added into a reaction kettle and mixed uniformly to obtain a curing agent having a solid content of 58-62 wt % and a rotational viscosity of 10-100 mPa·s at 25° C.;

[0057] ③ Preparation of adhesive: The main agent and the curing agent are mixed evenly in a mass ratio of 20:1.2-2, so as to obtain the above-mentioned room temperature fast-curing medium-resistant reverse polyurethane laminating adhesive.

[0058] Preferably, in the above adhesive, the polyester polyol of the main agent is a hydroxyl-terminated polyester polyol prepared by the following method through the synthesis of a carboxyl-terminated prepolymer and a hydroxyl-terminated reaction, including:

[0059] ① Synthesis of carboxyl-terminated prepolymer: add isophthalic acid, adipic acid, diethylene glycol, a catalyst and an antioxidant into a polyester synthesis reactor, wherein the acid is in excess of 40%, stepwise increase the temperature to 220-230°C, react for 6-8 hours until the acid value is stable, and then prepare the carboxyl-terminated prepolymer;

[0060] ② Hydroxyl-terminated reaction: After the above reaction is completed, diethylene glycol, neopentyl glycol and trimethylolpropane are continuously added to the above synthesis kettle for hydroxyl-terminated reaction, with an alcohol excess of 60%, the starting temperature is set to 150°C, the temperature is increased by 10°C every 30 minutes, the temperature is increased stepwise and stirred until the material is melted, and then the temperature is kept at 200°C for 3 to 4 hours, and the synthesis kettle is evacuated, the kettle temperature is controlled at 235 to 245°C, and pre-evacuated at -0.02MPa, -0.04MPa, -0.06MPa, and -0.08MPa for 30 minutes respectively, and then a long vacuum operation is performed, the vacuum degree reaches -0.1MPa, and the long vacuum time is 1 to 2 hours, until the acid value of the product is less than 1.5mgKOH / g, and the hydroxyl value of the product reaches 51 to 62mgKOH / g, thereby obtaining a hydroxy-terminated polyester polyol.

[0061] In summary, it can be seen that the reverse polyurethane laminating adhesive of room temperature fast solid medium resistance provided by the embodiment of the present invention, by adopting a unique polyester polyol step-by-step synthesis process, can ensure the presence of cross-linked hydroxyl groups on each molecular segment, and the polyester polyol polymerized in steps, the relative molecular mass distribution is narrower, the molecular structure is more regular, and the performance is more excellent and stable. And the introduction of triols can improve the cross-linking density to a certain extent, and then improve the heat resistance and chemical medium resistance performance. Secondly, by matching the hydrolysis-resistant environmentally friendly titanium-containing metal catalyst, it is stable and non-hydrolyzed, and the catalytic effect can be maintained for a long time during the polyester polyol synthesis process without additional addition. The laminating adhesive can be used for the composite of the daily chemical soft packaging structure containing strong acid and alkali corrosive contents, such as shampoo, softener, floor washing liquid, kitchen washing liquid, hair dye and other daily chemical product soft packaging fields, with excellent chemical medium resistance and room temperature fast curing advantages.

[0062] In order to more clearly demonstrate the technical solution and technical effects provided by the present invention, the solution provided by the embodiment of the present invention is described in detail with specific embodiments below.

[0063] Example 1

[0064] This embodiment provides a room temperature fast solid medium resistant reverse polyurethane laminating adhesive, the preparation method of which includes (each raw material is calculated by weight):

[0065] (1) Preparation of polyester polyols:

[0066] ① Synthesis of terminal carboxyl prepolymer: 22 parts by mass of isophthalic acid, 23 parts by mass of adipic acid, 18 parts by mass of diethylene glycol, 0.03 parts by mass of catalyst and 0.03 parts by mass of antioxidant were added to a polyester synthesis reactor, the temperature was increased stepwise to 220-230° C., and the reaction was performed for 7 hours until the acid value was stable to obtain a terminal carboxyl prepolymer;

[0067] ② Hydroxyl-terminated reaction: After the above reaction is completed, 9 parts by mass of diethylene glycol, 20 parts by mass of neopentyl glycol and 8 parts by mass of trimethylolpropane are continuously added to the above synthesis reactor for hydroxyl-terminated reaction, the starting temperature is set to 150°C, the temperature is increased by 10°C every 30 minutes, the temperature is increased stepwise and stirred until the material is melted, and then the temperature is kept at 200°C for 3.5 hours; the synthesis reactor is evacuated, the reactor temperature is controlled at 235-245°C, and the reactor is pre-evacuated for 30 minutes at -0.02MPa, -0.04MPa, -0.06MPa, and -0.08MPa, respectively, and then a long vacuum operation is performed, the vacuum degree reaches -0.1MPa, and the long vacuum time is 2 hours, until the acid value of the product is less than 1.5mgKOH / g, and the hydroxyl value of the product reaches 55mgKOH / g, thereby obtaining a hydroxyl-terminated polyester polyol;

[0068] (2) preparing a main agent: adding 50 parts by weight of the polyester polyol and 19 parts by weight of isocyanate into a reaction kettle and mixing them evenly, heating the kettle to 80° C. and reacting for 5 hours, then lowering the system temperature to 60° C., adding 1 part by weight of polythiol and 30 parts by weight of ethyl acetate, and preparing a main agent having a solid content of 70 wt % and a rotational viscosity of 1500 mPa·s at 25° C.;

[0069] (3) preparing a curing agent: adding 43 parts by weight of the above-mentioned polyether polyol, 19 parts by weight of polycaprolactone polyol, 0.1 parts by weight of a silane coupling agent, and 38 parts by weight of ethyl acetate into a reaction kettle and mixing them uniformly to obtain a curing agent having a solid content of 62 wt % and a rotational viscosity of 55 mPa·s at 25° C.;

[0070] (4) Preparation of adhesive: The main agent and the curing agent are mixed evenly in a mass ratio of 20:1.2 to obtain the room temperature fast-curing medium-resistant reverse polyurethane laminating adhesive of this embodiment.

[0071] Example 2

[0072] This embodiment provides a room temperature fast solid medium resistant reverse polyurethane laminating adhesive, the preparation method of which includes:

[0073] (1) Preparation of polyester polyols:

[0074] ① Synthesis of terminal carboxyl prepolymer: 24 parts by mass of isophthalic acid, 21 parts by mass of adipic acid, 20 parts by mass of diethylene glycol, 0.03 parts by mass of catalyst and 0.03 parts by mass of antioxidant were added into a polyester synthesis reactor, the temperature was increased stepwise to 220-230° C., and the reaction was performed for 7 hours until the acid value was stable to obtain a terminal carboxyl prepolymer;

[0075] ② Hydroxyl-terminated reaction: After the above reaction is completed, 8 parts by mass of diethylene glycol, 21 parts by mass of neopentyl glycol and 6 parts by mass of trimethylolpropane are continuously added to the above synthesis reactor for hydroxyl-terminated reaction, the starting temperature is set to 150°C, the temperature is increased by 10°C every 30 minutes, the temperature is increased stepwise and stirred until the material is melted, and then kept at 200°C for 3.5 hours; the synthesis reactor is evacuated, the reactor temperature is controlled at 235-245°C, and pre-evacuated at -0.02MPa, -0.04MPa, -0.06MPa, and -0.08MPa for 30 minutes respectively, and then a long vacuum operation is performed, the vacuum degree reaches -0.1MPa, and the long vacuum time is 1.5 hours, until the acid value of the product is less than 1.5mgKOH / g, and the hydroxyl value of the product reaches 57mgKOH / g, thereby obtaining a hydroxyl-terminated polyester polyol;

[0076] (2) preparing a main agent: adding 50 parts by weight of the polyester polyol and 18 parts by weight of isocyanate into a reaction kettle and mixing them evenly, heating the kettle to 80° C. and reacting for 5 hours, then lowering the system temperature to 60° C., adding 3 parts by weight of polythiol and 29 parts by weight of ethyl acetate, and preparing a main agent having a solid content of 70 wt % and a rotational viscosity of 1900 mPa·s at 25° C.;

[0077] (3) preparing a curing agent: adding 45 parts by weight of the above-mentioned polyether polyol, 16 parts by weight of polycaprolactone polyol, 0.1 parts by weight of a silane coupling agent, and 39 parts by weight of ethyl acetate into a reaction kettle and mixing them uniformly to obtain a curing agent having a solid content of 61 wt % and a rotational viscosity of 47 mPa·s at 25° C.;

[0078] (4) Preparation of adhesive: The main agent and the curing agent are mixed evenly in a mass ratio of 20:1.5, thereby obtaining the room temperature fast-curing medium-resistant reverse polyurethane laminating adhesive of this embodiment.

[0079] Example 3

[0080] This embodiment provides a room temperature fast solid medium resistant reverse polyurethane laminating adhesive, the preparation method of which includes (each raw material is calculated by weight):

[0081] (1) Preparation of polyester polyols:

[0082] ① Synthesis of terminal carboxyl prepolymer: 25 parts by mass of isophthalic acid, 22 parts by mass of adipic acid, 21 parts by mass of diethylene glycol, 0.03 parts by mass of catalyst and 0.03 parts by mass of antioxidant were added to a polyester synthesis reactor, the temperature was increased stepwise to 220-230° C., and the reaction was performed for 7 hours until the acid value was stable to obtain a terminal carboxyl prepolymer;

[0083] ② Hydroxyl-terminated reaction: After the above reaction is completed, 6 parts of diethylene glycol, 18 parts by mass of neopentyl glycol and 8 parts by mass of trimethylolpropane are continuously added to the above synthesis kettle for hydroxyl-terminated reaction, the starting temperature is set to 150°C, the temperature is increased by 10°C every 30 minutes, the temperature is increased step by step and stirred until the material is melted, and then the temperature is kept at 200°C for 3.5 hours, the synthesis kettle is vacuumed, the kettle temperature is controlled at 235-245°C, and the temperature is pre-evacuated at -0.02MPa, -0.04MPa, -0.06MPa, and -0.08MPa for 30 minutes respectively, and then a long vacuum operation is performed, the vacuum degree reaches -0.1MPa, and the long vacuum time is 2 hours, until the acid value of the product is less than 1.5mgKOH / g, and the hydroxyl value of the product reaches 54mgKOH / g, thereby obtaining a hydroxyl-terminated polyester polyol;

[0084] (2) Preparation of a main agent: 49 parts by weight of the polyester polyol and 18 parts by weight of isocyanate were added to a reaction kettle and mixed evenly, and the mixture was heated to 80° C. and reacted for 4.5 hours. The system temperature was then lowered to 60° C., and 3 parts by weight of polythiol and 30 parts by weight of ethyl acetate were added to obtain a main agent having a solid content of 70 wt % and a rotational viscosity of 1700 mPa·s at 25° C.;

[0085] (3) preparing a curing agent: adding 43 parts by weight of the above-mentioned polyether polyol, 17 parts by weight of polycaprolactone polyol, 0.1 parts by weight of a silane coupling agent, and 40 parts by weight of ethyl acetate into a reaction kettle and mixing them uniformly to obtain a curing agent having a solid content of 60 wt % and a rotational viscosity of 52 mPa·s at 25° C.;

[0086] (4) Preparation of adhesive: The main agent and the curing agent are mixed evenly in a mass ratio of 20:2 to obtain the room temperature fast-curing medium-resistant reverse polyurethane laminating adhesive of this embodiment.

[0087] Performance testing:

[0088] The use and performance testing methods of the room temperature fast solid medium resistant reverse polyurethane laminating adhesive provided in Examples 1, 2 and 3 of the present invention are as follows:

[0089] Working fluid concentration: 35-45%

[0090] Ripening conditions: 35-40°C x 24 hours

[0091] Glue amount on dry basis: 2.8-3.5g / m 2

[0092] Composite structure: PA / / PE, PET / / VMPET / / PE

[0093] Immersion test method: Cut the sample film into 2.5cm×2.5cm squares, immerse it completely in different commercially available foreign contents, and age it at 60℃ for 2 weeks.

[0094] The room temperature fast solid medium resistant reverse polyurethane laminating adhesive provided by the present invention was subjected to a peel strength comparison test with a commercially available adhesive of the same type (comparative example). The peel strengths are shown in Table 1 below:

[0095] Table 1 is the test result data of the peeling strength comparison between the room temperature fast solid medium resistant reverse polyurethane laminating adhesive of the present invention and the same type of adhesive on the market

[0096]

[0097] It can be seen from Table 1 that the peel strength performance of the room temperature fast-curing medium-resistant reverse polyurethane laminating adhesive provided by the present invention is comparable to or even better than that of the same type of adhesive available on the market (comparative example).

[0098] The room temperature fast-curing medium-resistant reverse polyurethane laminating adhesive provided by the present invention was subjected to a comparative test on the resistance to immersion of contents with a commercially available adhesive of the same type (comparative example). The results are shown in Table 2 below:

[0099] Table 2 is the comparative test data of the room temperature fast solid medium resistant reverse polyurethane laminating adhesive of the present invention and the same type of commercial adhesive (comparative example) for the resistance to content immersion

[0100]

[0101] It can be seen from Table 2 that the medium resistance performance of the room temperature fast-curing medium-resistant reverse polyurethane laminating adhesive provided by the present invention is comparable to that of the same type of adhesive available on the market (comparative example), and meets the performance requirements.

[0102] The room temperature fast solidifying medium resistant reverse polyurethane laminating adhesive provided by the present invention was compared with the commercially available adhesive of the same type (comparative example) in a 40°C reaction completion rate test, and the results are shown in the following Table 3:

[0103] Table 3 is the comparison test results of the reaction completion rate at 40°C of the reverse polyurethane laminating adhesive of the present invention with the medium-resistant fast solidification at room temperature and the commercially available adhesive of the same type (comparative example)

[0104] Reaction time 12h 24h 36h 48h Example 1 68.03％ 78.22％ 85.32％ 92.16％ Example 2 67.85％ 78.14％ 85.12％ 91.82％ Example 3 67.63％ 77.32％ 84.21％ 91.46％ Comparative Example 67.09％ 78.29％ 85.08％ 91.55％

[0105] It can be seen from Table 3 that the reaction speed of the room temperature fast-curing medium-resistant reverse polyurethane laminating adhesive provided by the present invention is comparable to or even higher than that of the same type of adhesive available on the market (comparative example).

[0106] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims. The information disclosed in the background technology section of this article is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as an admission or in any form that the information constitutes prior art known to those skilled in the art.

Claims

1. A room temperature fast solid medium resistant reverse polyurethane laminating adhesive, characterized in that: The laminating adhesive is composed of a main agent and a curing agent in a mass ratio of 20:1.2-2; wherein, The main agent is an ethyl acetate solution of an NCO-terminated polyisocyanate resin prepared by reacting polyester polyol, polythiol and isocyanate; the solid content of the main agent is 68-72wt%, and the rotational viscosity at 25°C is 1000-2500mPa·s; The curing agent is an ethyl acetate solution of polyether polyol, polycaprolactone polyol and a coupling agent, the solid content of the curing agent is 58-62wt%, and the rotational viscosity at 25°C is 10-100mPa·s.

2. The room temperature fast solid medium resistant reverse polyurethane laminating adhesive according to claim 1, characterized in that: In the main agent, the usage of each component is as follows by mass: 49-52 parts of polyester polyol, 18-21 parts of isocyanate, 1-3 parts of polythiol and 28-32 parts of ethyl acetate.

3. The room temperature fast solid medium resistant reverse polyurethane laminating adhesive according to claim 2, characterized in that: In the main agent, the polyester polyol has a hydroxyl value of 51-62 mgKOH / g, an acid value of less than 1.5 mgKOH / g, and an average molecular weight of 1800-2200. The polyester polyol is prepared from dibasic acid, diol, triol, antioxidant and catalyst.

4. The room temperature fast solid medium resistant reverse polyurethane laminating adhesive according to claim 3, characterized in that: In the polyester polyol of the main agent, the amount of each component is as follows by mass: 20-25 parts of isophthalic acid, 21-25 parts of adipic acid, 18-22 parts of neopentyl glycol, 23-32 parts of diethylene glycol, 6-9 parts of trihydroxypropane, 0.02-0.06 parts of antioxidant and 0.01-0.04 parts of catalyst.

5. The room temperature fast solid medium resistant reverse polyurethane laminating adhesive according to claim 4, characterized in that: In the polyester polyol of the main agent, The catalyst is one or two of Guangzhou Yourun's AUCAT-ES01 and AUCAT-ES02 hydrolysis-resistant environmentally friendly titanium-containing metal catalysts; The antioxidant is at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, triphenyl phosphite, and β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate.

6. The room temperature fast solid medium resistant reverse polyurethane laminating adhesive according to any one of claims 1 to 5, characterized in that: The polythiol in the main agent adopts the tetrafunctional polythiol 440HE produced by Bluelobeck; The isocyanate in the main agent is one or two of 2,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate and isophorone diisocyanate.

7. The room temperature fast solid medium resistant reverse polyurethane laminating adhesive according to any one of claims 1 to 5, characterized in that: The amounts of the components in the curing agent are as follows by mass: 43-47 parts of polyether polyol, 16-22 parts of polycaprolactone polyol, 0.08-0.16 parts of silane coupling agent and 38-42 parts of ethyl acetate.

8. The room temperature fast solid medium resistant reverse polyurethane laminating adhesive according to claim 7, characterized in that: In the curing agent, the polyether polyol is one of MN-700, MN-1000, and DL-4000D produced by Shandong Bluestar Dongda; The polycaprolactone polyol is one or two of PCL-2044, PCL-2053, PCL-3037, PCL-3057 and PCL-2200C produced by Hunan Juren; The silane coupling agent is at least one of (3-aminopropyl)trimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidyloxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, and N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane.

9. A method for preparing the room temperature fast solid medium resistant reverse polyurethane laminating adhesive according to any one of claims 1 to 8, characterized in that: include: The main agent and curing agent are prepared separately, wherein: Preparation of the main agent: Take the raw materials according to the formula of the room temperature fast solid medium resistant reverse polyurethane laminating adhesive according to any one of claims 1 to 8, add the polyester polyol and isocyanate in the raw materials into a reaction kettle and mix them evenly, heat the temperature to 80-85°C to react for 4-5 hours, then reduce the system temperature to 60°C, add polythiol and ethyl acetate, and obtain a product with a solid content of 68-72wt% and a rotational viscosity of 1000-2500mPa·s at 25°C, which is the main agent; Preparation of curing agent: adding polyether polyol, polycaprolactone polyol, silane coupling agent and ethyl acetate in the raw materials into a reaction kettle and mixing them evenly to obtain a product with a solid content of 58-62wt% and a rotational viscosity of 10-100mPa·s at 25°C, which is the curing agent; Preparation of laminating adhesive: The main agent and the curing agent are mixed evenly in a mass ratio of 20:1.2-2 to obtain the room temperature fast-curing medium-resistant reverse polyurethane laminating adhesive.

10. The method for preparing the room temperature fast solid medium resistant reverse polyurethane laminating adhesive according to claim 9, characterized in that: The polyester polyol in the main agent is a hydroxyl-terminated polyester polyol prepared by the following method through the synthesis of carboxyl-terminated prepolymer and hydroxyl-terminated reaction, including: Step 11, synthesizing a carboxyl-terminated prepolymer: adding 20 to 25 parts of isophthalic acid, 21 to 25 parts of adipic acid, 18 to 21 parts of diethylene glycol, 0.02 to 0.06 parts of an antioxidant and 0.01 to 0.04 parts of a catalyst to a polyester synthesis reactor, wherein the acid is in excess of 40%, stepwise heating to 220 to 230° C., reacting for 6 to 8 hours until the acid value is measured to be stable and unchanged, to obtain a carboxyl-terminated prepolymer; Step 12, hydroxyl-terminated reaction: After the above reaction is completed, 5 to 11 parts of diethylene glycol, 18 to 22 parts of neopentyl glycol and 6 to 9 parts of trimethylolpropane are continuously added to the above synthesis reactor for hydroxyl-terminated reaction, with an excess of 60% of alcohol, the starting temperature is set to 150°C, the temperature is increased by 10°C every 30 minutes, the temperature is increased stepwise and stirred until the material is melted, and then the temperature is kept at 200°C for 3 to 4 hours, and the synthesis reactor is evacuated, the reactor temperature is controlled at 235 to 245°C, and pre-evacuated at -0.02MPa, -0.04MPa, -0.06MPa, and -0.08MPa for 30 minutes respectively, and then a long vacuum operation is performed, the vacuum degree reaches -0.1MPa, and the long vacuum time is 1 to 2 hours, until the acid value of the product is less than 1.5mgKOH / g, and the hydroxyl value of the product reaches 51 to 62mgKOH / g, that is, the polyester polyol with terminal hydroxyl groups in the main agent is obtained.

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