Low-cost temperature-resistant quick-drying polyether solvent adhesive and preparation method thereof

Abstract

The invention discloses a low-cost temperature-resistant quick-drying polyether solvent adhesive and a preparation method thereof, and belongs to the field of polyurethane adhesives for composite flexible packages. The solvent type adhesive is prepared by mixing a component A and a component B according to a weight ratio of 1: (0.8-1.2), wherein the component A is hydroxyl-terminated resin obtained by carrying out polymerization reaction on a mixture of polyester polyol and polyether polyol and isocyanate; and the component B is isocyanate-terminated resin obtained by carrying out polymerization reaction on a mixture of two polyether polyols and isocyanate. By adjusting the proportion of polyester and polyether in the component A and the proportion of polyether polyol with different molecular weights in the component B, the temperature required for reaction of the component A and the component B is low, the reaction speed is high, the crosslinking degree of an adhesive film after reaction is high, and the polyether adhesive can be cured at low temperature, and is short in curing time and good in heat resistance.

Description

Technical Field

[0001] The invention relates to the technical field of polyurethane adhesives for composite flexible packaging, and in particular to a low-cost, temperature-resistant, quick-drying polyether solvent adhesive and a preparation method thereof. Background Art

[0002] As one of the important links in the modern industrial chain, the packaging industry is closely related to all walks of life. Its development is closely related to the improvement of the national economic level and people's living standards. In recent years, with the rapid development of social economy and consumption upgrading, the packaging industry has gradually changed from traditional protective functions to a more innovative, environmentally friendly and functional development direction. As a multifunctional and high-performance packaging material, polyurethane packaging glue has attracted much attention for its excellent adhesion, wear resistance and elasticity.

[0003] Traditional solvent-based polyurethane adhesives are two-component. The main agent is generally a high molecular weight hydroxyl-terminated resin obtained by extending the polyester structure with diisocyanate. The polyester structure can be adjusted according to the required performance. Due to the problem of free TDI, the curing agent usually uses L75 prepared by a well-known manufacturer. This type of polyurethane adhesive has a dense cross-linking network, high strength between composite films, and good heat resistance. In order to cooperate with the use of this type of adhesive, domestic packaging and printing manufacturers are currently equipped with a aging room, which is mainly used for aging after the composite of different film rolls. The aging time is usually more than 48 hours and the aging temperature is about 45-55°C. This is because traditional solvent-based adhesives have a slow aging speed and high aging temperature requirements. If the aging temperature is not enough or the aging time is short, the composite film material will have poor temperature resistance when the aging is insufficient. Quality problems such as delamination or wrinkles are very likely to occur during the bag making heat sealing process or after boiling. Further extending the aging time will reduce work efficiency. There are also some adhesives on the market that use diisocyanate-extended polyether structures, such as solvent-free adhesives, which are usually used more frequently. Their reaction speed is slightly faster than that of polyester adhesives, but their chain segments are softer, so their heat resistance is worse than that of polyester adhesives.

[0004] In summary, the above-mentioned traditional polyester-type polyurethane adhesives have the problems of slow curing speed, high curing temperature requirement and poor heat resistance.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The purpose of the present invention is to provide a low-cost, temperature-resistant, quick-drying polyether solvent adhesive and a preparation method thereof, which has low cost, can be cured at low temperature, has a short curing time and good heat resistance, thereby solving the above-mentioned technical problems existing in the prior art.

[0007] The objective of the present invention is achieved through the following technical solutions:

[0008] A low-cost, heat-resistant, quick-drying polyether solvent adhesive, the adhesive is composed of a mixture of component A and component B in a weight ratio of 1:0.8-1.2; wherein,

[0009] The component A is a hydroxyl-terminated resin obtained by polymerization of a mixture of polyester polyol and polyether polyol with isocyanate; in the mixture of polyester polyol and polyether polyol, the weight ratio of polyester polyol to polyether polyol is 1:2-4;

[0010] The B component is an isocyanate-terminated resin obtained by polymerization reaction of a mixture of two polyether polyols with different molecular weights and isocyanate; in the mixture of the two polyether polyols with different molecular weights, the weight ratio of the low molecular weight polyether polyol to the high molecular weight polyether polyol is 4:1-2.

[0011] Preferably, in the component A of the solvent adhesive, the weight ratio of the isocyanate to the mixture of polyester polyol and polyether polyol is 1:1-3;

[0012] The hydroxyl-terminated resin of component A is obtained by condensing diisocyanate with a mixture of polyester polyol and polyether polyol at 80-90°C, and has a hydroxyl value of 5-10 mgKOH / g, a viscosity of 4000-6000 mpa.s at 25°C, and a solid content of 60±5%.

[0013] Preferably, in the above solvent glue, the average molecular weight of the polyester polyol in the A component is 500-2000, and it is prepared by a common condensation polymerization method using small molecule polyacid, small molecule polyol, antioxidant and catalyst as raw materials.

[0014] Preferably, in the above solvent glue, the small molecular weight polyacid of the polyester polyol in component A is one or both of adipic acid and terephthalic acid;

[0015] The small molecule polyol is one or more of diethylene glycol, ethylene glycol, 1,4-butanediol, and neopentyl glycol;

[0016] The antioxidant is triphenyl phosphite;

[0017] The catalyst is tetra-n-butyl titanate.

[0018] Preferably, in the above solvent glue, the isocyanate in the component A is toluene diisocyanate;

[0019] The average molecular weight of the polyether polyol in the A component is 500-2000.

[0020] Preferably, in the above solvent glue, the weight ratio of the isocyanate in the B component to the mixture of two polyether polyols with different molecular weights is 1:1-2;

[0021] The isocyanate-terminated resin of component B is a product obtained by reacting isocyanate with a mixture of two polyether polyols with different molecular weights at 80-90° C., with an NCO value of 3-5%, a viscosity of 500-1000 mPa.s at 25° C., and a solid content of 50±5%.

[0022] Preferably, in the above solvent glue, in the mixture of two polyether polyols with different molecular weights in the B component, the average molecular weight of the low molecular weight polyether polyol is 500-2000, and the average molecular weight of the high molecular weight polyether polyol is 2000-4000;

[0023] The isocyanate in the B component is one or more of diphenylmethane diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate.

[0024] A method for preparing the low-cost, temperature-resistant, quick-drying polyether solvent adhesive of the present invention comprises:

[0025] Prepare component A and component B separately, wherein:

[0026] Preparation of component A:

[0027] A mixture of polyol polyol and polyether polyol formed by mixing in a weight ratio of 1:2 to 4 is added to a container, ethyl acetate accounting for 20% of the total weight of the mixture of polyol polyol and polyether polyol is added and stirred evenly, and then isocyanate is added, and the mixture is heated to 80 to 90° C. and reacted for 3 to 5 hours. After cooling to below 50° C., ethyl acetate accounting for 20% of the total weight of the mixture of polyol polyol and polyether polyol is added and discharged, thereby obtaining component A;

[0028] Preparation of component B:

[0029] A mixture of two polyether polyols with different molecular weights formed by mixing a low molecular weight polyether polyol and a high molecular weight polyether polyol in a weight ratio of 4:1-2 is added to a container, ethyl acetate accounting for 25% of the total weight of the mixture of the two polyether polyols with different molecular weights is added and stirred evenly, and then isocyanate is added, and the mixture is heated to 80-90° C. and reacted for 3-5 hours, and the mixture is cooled to below 50° C. and ethyl acetate accounting for 25% of the total weight of the mixture of the two polyether polyols with different molecular weights is added and then discharged to obtain component B;

[0030] Preparation of polyether solvent adhesive: Mix the above-prepared component A and component B in a weight ratio of 1:0.8-1.2, add ethyl acetate to dilute to the required working solution concentration to obtain the polyether solvent adhesive.

[0031] Preferably, in the above method, the polyester polyol in component A is prepared in the following manner, including:

[0032] The small molecule polyacid and the small molecule polyol are added into the polyester kettle in a weight ratio of 1:1 to 1.5, and then 500 ppm of antioxidant and 50 ppm of catalyst are added, and the polyester polyol is prepared by the commonly used esterification condensation method.

[0033] Compared with the prior art, the low-cost, temperature-resistant, quick-drying polyether solvent adhesive and the preparation method thereof provided by the present invention have the following beneficial effects:

[0034] (1) Component A of the present invention is composed of a polyester polyol having an average molecular weight of 500 to 2000 and a polyether polyol having an average molecular weight of 500 to 2000. Polyester polyol has more side group structures, which are easy to form hydrogen bonds with surrounding groups, thereby increasing the degree of crosslinking. However, the molecular weight of polyether polyol is relatively small. When the molecular weight of the final resin is comparable to that of other adhesives, the smaller the molecular weight of polyether polyol, the more carbamate groups it will obtain by reacting with isocyanate, that is, the higher the hard segment content, which provides the film with stronger rigidity and a certain degree of crosslinking, thereby improving the temperature resistance of the adhesive.

[0035] (2) The component B of the present invention is composed of a polyether polyol with an average molecular weight of 500-2000 and a polyether polyol with an average molecular weight of 2000-4000 in a weight ratio of 4:1-2. This ratio is the most suitable ratio. If the polyether polyol with a molecular weight of 500-2000 exceeds this ratio, the resin molecular weight is small, the rigidity is large, and the flexibility of the film is poor, which will eventually lead to a low peel strength of the prepared composite film. If the polyether polyol with a molecular weight of 2000-4000 exceeds this ratio, the film is soft and the heat resistance of the composite film is poor, which is manifested as poor thermal creep performance of the composite film.

[0036] (3) In the present invention, both component A and component B use polyether polyols with an average molecular weight of 500-2000. The molecular weight of the polyol is relatively small. When polymerized with isocyanate groups to form macromolecular resins, the molecular weight distribution of the resins is relatively wide, among which there are some resins with relatively small molecular weights. Such resins have small molecular weights and high reactivity. During the reaction of component A and component B, they can react and crosslink quickly, and pull the reaction of the remaining high molecular weight resins, thereby increasing the curing speed of the adhesive. In addition, the polyether polyol chain segments are soft, and the glass transition temperature of the polyurethane adhesive prepared therefrom is low. Therefore, the chain segments can also move freely at relatively low temperatures, so the curing temperature of the adhesive is also relatively low.

[0037] (4) The present invention has strong versatility for various composite film structures when component A and component B are used in a mass ratio of 1: (0.8-1.2). If the ratio of component A to component B is greater than this ratio, that is, the content of isocyanate-based components is small and the film is softer, then it is beneficial for ordinary structures, such as OPP / CPP, OPP / VMCPP, PET / VMCPP, etc., and its peel strength is higher, but for aluminum foil structures, such as PET / Al / PE structure, the inner layer strength is poor. If the ratio of component A to component B is less than this ratio, that is, when the isocyanate-based components are more, the film is harder, and for ordinary structures, ink or aluminum plating transfer is prone to occur, thereby reducing the peel strength of the composite film, but the strength of the inner layer of the aluminum foil structure is increased. After exploration, this ratio has better effects on various composite structures.

[0038] (5) Component A and component B are prepared in the present invention. The raw materials used for both are relatively common in the art and are relatively low in price. Component A and component B have low solid content and high solvent content, while ethyl acetate is relatively low in price. Therefore, the overall cost of the adhesive of the present invention is relatively low. The component B used in the market is L75, which is relatively expensive, resulting in a relatively high overall cost of the adhesive. DETAILED DESCRIPTION

[0039] 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.

[0040] First, the terms that may be used in this article are explained as follows:

[0041] 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”.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] The embodiment of the present invention provides a low-cost, temperature-resistant, quick-drying polyether solvent adhesive, which is composed of a mixture of component A and component B in a weight ratio of 1:0.8 to 1.2; wherein,

[0048] The component A is a hydroxyl-terminated resin obtained by polymerization of a mixture of polyester polyol and polyether polyol with isocyanate; in the mixture of polyester polyol and polyether polyol, the weight ratio of polyester polyol to polyether polyol is 1:2-4;

[0049] The B component is an isocyanate-terminated resin obtained by polymerization reaction of a mixture of two polyether polyols with different molecular weights and isocyanate; in the mixture of the two polyether polyols with different molecular weights, the weight ratio of the low molecular weight polyether polyol to the high molecular weight polyether polyol is 4:1-2.

[0050] Preferably, in the component A of the solvent adhesive, the weight ratio of the isocyanate to the mixture of polyester polyol and polyether polyol is 1:1-3;

[0051] The hydroxyl-terminated resin of component A is obtained by condensing diisocyanate with a mixture of polyester polyol and polyether polyol at 80-90°C, and has a hydroxyl value of 5-10 mgKOH / g, a viscosity of 4000-6000 mpa.s at 25°C, and a solid content of 60±5%.

[0052] Preferably, in the above solvent glue, the average molecular weight of the polyester polyol in the A component is 500-2000, and it is prepared by a common condensation polymerization method using small molecule polyacid, small molecule polyol, antioxidant and catalyst as raw materials.

[0053] Preferably, in the above solvent glue, the small molecular weight polyacid of the polyester polyol in component A is one or both of adipic acid and terephthalic acid;

[0054] The small molecule polyol is one or more of diethylene glycol, ethylene glycol, 1,4-butanediol, and neopentyl glycol;

[0055] The antioxidant is triphenyl phosphite;

[0056] The catalyst is tetra-n-butyl titanate.

[0057] Preferably, in the above solvent glue, the isocyanate in the component A is toluene diisocyanate;

[0058] The average molecular weight of the polyether polyol in the A component is 500-2000.

[0059] Preferably, in the above solvent glue, the weight ratio of the isocyanate in the B component to the mixture of two polyether polyols with different molecular weights is 1:1-2;

[0060] The isocyanate-terminated resin of component B is a product obtained by reacting isocyanate with a mixture of two polyether polyols with different molecular weights at 80-90° C., with an NCO value of 3-5%, a viscosity of 500-1000 mPa.s at 25° C., and a solid content of 50±5%.

[0061] Preferably, in the above solvent glue, in the mixture of two polyether polyols with different molecular weights in the B component, the average molecular weight of the low molecular weight polyether polyol is 500-2000, and the average molecular weight of the high molecular weight polyether polyol is 2000-4000;

[0062] The isocyanate in the B component is one or more of diphenylmethane diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate.

[0063] The embodiment of the present invention also provides a method for preparing the above-mentioned low-cost, heat-resistant, quick-drying polyether solvent adhesive, comprising:

[0064] Prepare component A and component B separately, wherein:

[0065] Preparation of component A:

[0066] A mixture of polyol polyol and polyether polyol formed by mixing in a weight ratio of 1:2 to 4 is added to a container, ethyl acetate accounting for 20% of the total weight of the mixture of polyol polyol and polyether polyol is added and stirred evenly, and then isocyanate is added, and the mixture is heated to 80 to 90° C. and reacted for 3 to 5 hours. After cooling to below 50° C., ethyl acetate accounting for 20% of the total weight of the mixture of polyol polyol and polyether polyol is added and discharged, thereby obtaining component A;

[0067] Preparation of component B:

[0068] A mixture of two polyether polyols with different molecular weights formed by mixing a low molecular weight polyether polyol and a high molecular weight polyether polyol in a weight ratio of 4:1-2 is added to a container, ethyl acetate accounting for 25% of the total weight of the mixture of the two polyether polyols with different molecular weights is added and stirred evenly, and then isocyanate is added, and the mixture is heated to 80-90° C. and reacted for 3-5 hours, and the mixture is cooled to below 50° C. and ethyl acetate accounting for 25% of the total weight of the mixture of the two polyether polyols with different molecular weights is added and then discharged to obtain component B;

[0069] Preparation of polyether solvent adhesive: Mix the above-prepared component A and component B in a weight ratio of 1:0.8-1.2, add ethyl acetate to dilute to the required working solution concentration to obtain the polyether solvent adhesive.

[0070] Preferably, in the above method, the polyester polyol in component A is prepared in the following manner, including:

[0071] The small molecule polyacid and the small molecule polyol are added into the polyester kettle in a weight ratio of 1:1 to 1.5, and then 500 ppm of antioxidant and 50 ppm of catalyst are added, and the polyester polyol is prepared by the commonly used esterification condensation method.

[0072] In summary, the solvent adhesive of the embodiment of the present invention is a low-cost, low-temperature curable, short curing time, and high-temperature resistant polyether polyurethane packaging adhesive, which can well meet the needs of the packaging adhesive market, improve packaging efficiency, reduce production costs, and is conducive to promoting the development of the packaging industry.

[0073] 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.

[0074] Embodiment 1:

[0075] This embodiment provides a low-cost, temperature-resistant, quick-drying polyether solvent adhesive, which is composed of component A and component B. The solvent adhesive is prepared in the following manner, including:

[0076] Preparation of polyester polyol required for component A: by mass, 3 parts of terephthalic acid, 5 parts of adipic acid, 3 parts of ethylene glycol, 5 parts of diethylene glycol, 1 part of neopentyl glycol, 500 ppm of antioxidant triphenyl phosphite and 50 ppm of catalyst tetra-n-butyl titanate are added to a polyester kettle, and after condensation polymerization, a polyester polyol with a hydroxyl value of 80 to 140 mgKOH / g is obtained.

[0077] Preparation of component A: first, by mass, add 1 part of the above-prepared polyester polyol and 3 parts of polyether polyols with a molecular weight of 500-2000 into a flask, add ethyl acetate accounting for 20% of the total weight of the mixture of polyol polyols and polyether polyols and stir evenly, add 1.5 parts of toluene diisocyanate, heat to 80-90°C and stir for 3-5 hours, cool to below 50°C, add ethyl acetate accounting for 20% of the total weight of the mixture of polyol polyols and polyether polyols, and obtain component A, which has a hydroxyl value of 5-10 mgKOH / g, a viscosity of 4000-6000 mPa.s at 25°C, and a solid content of 60±5%.

[0078] Preparation of component B: first, by mass, add 4 parts of a first polyether polyol with a molecular weight of 500 to 2000 and 1.5 parts of a second polyether polyol into a flask, then add ethyl acetate accounting for 25% of the total weight of the first polyether polyol and the second polyether polyol, stir evenly, add 3 parts of diphenylmethane diisocyanate into the flask, react at 80 to 90° C. for 3 to 5 hours, cool to below 50° C., add ethyl acetate accounting for 25% of the total weight of the first polyether polyol and the second polyether polyol, stir evenly, and obtain component B, whose NCO value is about 3 to 5%, viscosity is 500 to 1000 mPa.s at 25° C., and solid content is 50±5%.

[0079] Preparation of solvent-based adhesive: Mix the above-prepared component A and component B in a weight ratio of 1:1, add ethyl acetate and dilute to the required working solution concentration to obtain the solvent-based adhesive.

[0080] Embodiment 2:

[0081] This embodiment provides a low-cost, temperature-resistant, quick-drying polyether solvent adhesive, which is composed of component A and component B. The solvent adhesive is prepared in the following manner, including:

[0082] Preparation of polyester polyol required for component A: by mass, 4 parts of terephthalic acid, 4 parts of adipic acid, 3 parts of ethylene glycol, 5 parts of diethylene glycol, 500 ppm of antioxidant triphenyl phosphite and 50 ppm of catalyst tetra-n-butyl titanate are added to a polyester kettle, and after condensation polymerization, a polyester polyol with a hydroxyl value of 80 to 140 mgKOH / g is obtained.

[0083] Preparation of component A: first, by mass, add 1 part of the above-prepared polyester polyol and 2 parts of polyether polyol with a molecular weight of 500-2000 into a flask, add ethyl acetate accounting for 20% of the total weight of the mixture of polyol polyol and polyether polyol and stir evenly, add 1.5 parts of toluene diisocyanate, heat to 80-90°C and stir for 3-5 hours, cool to below 50°C, add ethyl acetate accounting for 20% of the total weight of the mixture of polyol polyol and polyether polyol, and obtain component A, which has a hydroxyl value of 5-10 mgKOH / g, a viscosity of 4000-6000 mPa.s at 25°C, and a solid content of 60±5%.

[0084] Preparation of component B: Same as in Example 1, see Example 1.

[0085] Preparation of solvent-based adhesive: Same as in Example 1, see Example 1.

[0086] Embodiment 3:

[0087] This embodiment provides a low-cost, temperature-resistant, quick-drying polyether solvent adhesive, which is composed of component A and component B. The solvent adhesive is prepared in the following manner, including:

[0088] Preparation of polyester polyol required for component A: Same as in Example 1, see Example 1.

[0089] Preparation of component A: Same as in Example 1, see Example 1.

[0090] Preparation of component B: first add 4 parts of polyether polyol 1 with a molecular weight of 500 to 2000 and 2 parts of polyether polyol 2 into a flask, then add ethyl acetate accounting for 25% of the total weight of the first polyether polyol and the second polyether polyol, stir evenly, add 4 parts of diphenylmethane diisocyanate into the flask, react at 80-90°C for 3-5 hours, cool to below 50°C, add ethyl acetate accounting for 25% of the total weight of the first polyether polyol and the second polyether polyol, stir evenly, and obtain component B, whose NCO value is about 3-5%, viscosity is 500-1000mpa.s at 25°C, and solid content is 50±5%.

[0091] Preparation of solvent-based adhesive: Same as in Example 1, see Example 1.

[0092] Embodiment 4:

[0093] This embodiment provides a low-cost, temperature-resistant, quick-drying polyether solvent adhesive, which is composed of component A and component B. The solvent adhesive is prepared in the following manner, including:

[0094] Preparation of polyester polyol required for component A: Same as in Example 1, see Example 1.

[0095] Preparation of component A: Same as in Example 1, see Example 1.

[0096] Preparation of component B: Same as in Example 1, see Example 1.

[0097] Preparation of solvent-based adhesive: Mix component A and component B in a weight ratio of 1:1.2, add ethyl acetate and dilute to the required working solution concentration.

[0098] In order to compare the performance of the solvent adhesive of each embodiment of the present invention, the following comparative examples are specially designed. These comparative examples are not prior arts, but are specially designed for comparing the performance of the solvent adhesive of each embodiment of the present invention.

[0099] Comparative Example 1:

[0100] This comparative example provides a solvent glue, which is composed of component A and component B, and its preparation method is as follows:

[0101] The polyester polyol and component A required for preparing component A are the same as those in Example 1.

[0102] Preparation of component B: first, by mass, add 9 parts of a first polyether polyol with a molecular weight of 500 to 2000 and 1 part of a second polyether polyol into a flask, then add ethyl acetate accounting for 25% of the total weight of the first polyether polyol and 1 part of the second polyether polyol, stir evenly, add 4 parts of diphenylmethane diisocyanate into the flask, react at 80 to 90° C. for 3 to 5 hours, cool to below 50° C., add ethyl acetate accounting for 25% of the total weight of the first polyether polyol and 1 part of the second polyether polyol, stir evenly, and obtain component B, whose NCO value is about 3 to 5%, viscosity is 500 to 1000 mPa.s at 25° C., and solid content is 50±5%.

[0103] Preparation of solvent-based adhesive: Same as in Example 1.

[0104] Comparative Example 2:

[0105] This comparative example provides a solvent glue, which is composed of component A and component B, and its preparation method is as follows:

[0106] The polyester polyol and component A required for preparing component A are the same as those in Example 1.

[0107] Preparation of component B: first add 1 part of a first polyether polyol with a molecular weight of 500 to 2000 and 1 part of a second polyether polyol into a flask, then add ethyl acetate accounting for 25% of the total weight of the first polyether polyol and 1 part of the second polyether polyol, stir evenly, add 4 parts of diphenylmethane diisocyanate into the flask, react at 80 to 90° C. for 3 to 5 hours, cool to below 50° C., add ethyl acetate accounting for 25% of the total weight of the first polyether polyol and 1 part of the second polyether polyol, stir evenly, and obtain component B, whose NCO value is about 3 to 5%, viscosity is 500 to 1000 mPa.s at 25° C., and solid content is 50±5%.

[0108] Preparation of solvent-based adhesive: Same as in Example 1.

[0109] Comparative Example 3:

[0110] This comparative example provides a solvent glue, which is composed of component A and component B, and its preparation method is as follows:

[0111] The polyester polyol, component A and component B required for preparing component A are the same as those in Example 1.

[0112] Preparation of solvent-based adhesive: Mix component A and component B in a weight ratio of 1:0.6, add ethyl acetate and dilute to the required working solution concentration.

[0113] Comparative Example 4:

[0114] This comparative example provides a solvent glue, which is composed of component A and component B, and its preparation method is as follows:

[0115] The polyester polyol, component A and component B required for preparing component A are the same as those in Example 1.

[0116] Preparation of solvent-based adhesive: Mix component A and component B in a weight ratio of 1:1.4, add ethyl acetate and dilute to the required working solution concentration.

[0117] Comparative Example 5:

[0118] This comparative example provides a solvent adhesive, which is a polyester-type two-component solvent adhesive that is widely used in the market.

[0119] Comparative Example 6:

[0120] This comparative example provides a solvent adhesive, which is a polyether two-component solvent adhesive for common structures developed by Beijing Gaomeng New Materials Co., Ltd.

[0121] The solvent-based two-component polyurethane adhesives prepared in Examples 1 to 4 and Comparative Examples 1 to 6 were compounded with ordinary OPP / CPP and PET / Al / PE structures, and the peel strength of the OPP / CPP structure after aging at 30°C and the peel strength and thermal creep performance of the aluminum foil inner layer structure at 30°C were tested according to the BB / T0039-2013 "Commodity Retail Packaging Bags" standard (the composite film was cut into 15 mm wide strips, torn open, a 100 g weight was hung on one end, and the other end was fixed in an oven. The length of the composite film pulled apart by the weight at 90°C was tested. The longer the length, the worse the heat resistance). The specific test results are shown in Table 1.

[0122] Table 1 is the test results table:

[0123]

[0124]

[0125] The results in Table 1 show that in Examples 1 to 4, the polyether polyurethane solvent adhesive provided by the present invention is used to compound the ordinary OPP / CPP structure and the PET / Al / PE aluminum foil structure. After aging at 30°C for 36 hours, the peel strength of the two representative structures is good, and the thermal creep performance of the inner layer of the aluminum foil structure is good, indicating that the adhesive also has good heat resistance.

[0126] Comparative Examples 1 and 2 respectively changed the ratio of polyether polyols with molecular weights of 500-2000 and 2000-4000 in component B. In Comparative Example 1, the ratio of polyether polyol 1 with molecular weights of 500-2000 was increased, and the results showed that the peel strength of the aluminum foil structure was reduced, but the heat resistance was still good. In Comparative Example 2, the ratio of polyether polyol 2 with molecular weights of 2000-4000 was increased, and the peel strength of the inner layer of the aluminum foil structure was higher, but the thermal creep was poor, that is, the heat resistance was slightly poor.

[0127] Comparative Examples 3 and 4 respectively changed the ratio of component A to component B in the solvent glue, wherein the content of component B was reduced in Comparative Example 3, resulting in poor crosslinking and softer segments, which resulted in higher peel strength of the common structure OPP / CPP, but poor peel strength and thermal creep of the inner layer of the aluminum foil. In Comparative Example 4, the content of component B was increased, resulting in a higher crosslinking degree, better peel strength and thermal creep performance of the inner layer of the aluminum foil structure, but poor peel strength for the common structure OPP / CPP structure.

[0128] Comparative Example 5 is a polyester two-component solvent adhesive that is widely used in the market. It is not fully matured after being matured at 30° C. for 36 hours. The composite film is sticky after being peeled off, and the peel strength and thermal creep are poor.

[0129] Comparative Example 6 is a polyether two-component solvent adhesive developed by Gaomeng Company for ordinary structures. It has no anti-stickiness when matured at 30°C and has good peel strength for ordinary structures. However, although it reacts completely to aluminum foil structures, it has low strength and poor heat resistance.

[0130] 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 low-cost, heat-resistant, quick-drying polyether solvent adhesive, characterized in that: The adhesive is composed of a mixture of component A and component B in a weight ratio of 1:0.8-1.2; wherein: The component A is a hydroxyl-terminated resin obtained by polymerization of a mixture of polyester polyol and polyether polyol with isocyanate; in the mixture of polyester polyol and polyether polyol, the weight ratio of polyester polyol to polyether polyol is 1:2-4; The B component is an isocyanate-terminated resin obtained by polymerization reaction of a mixture of two polyether polyols with different molecular weights and isocyanate; in the mixture of the two polyether polyols with different molecular weights, the weight ratio of the low molecular weight polyether polyol to the high molecular weight polyether polyol is 4:1-2.

2. The low-cost, heat-resistant, quick-drying polyether solvent adhesive according to claim 1, characterized in that: In the component A, the weight ratio of the isocyanate to the mixture of polyester polyol and polyether polyol is 1:1-3; The hydroxyl-terminated resin of component A is obtained by condensing diisocyanate with a mixture of polyester polyol and polyether polyol at 80-90°C, and has a hydroxyl value of 5-10 mgKOH / g, a viscosity of 4000-6000 mpa.s at 25°C, and a solid content of 60±5%.

3. The low-cost, temperature-resistant, quick-drying polyether solvent adhesive according to claim 1 or 2, characterized in that: The polyester polyol in component A has an average molecular weight of 500-2000 and is prepared by a common condensation polymerization method by mixing a small molecule polyacid and a small molecule polyol in a weight ratio of 1:1-1.5, adding 500 ppm of an antioxidant and 50 ppm of a catalyst.

4. The low-cost, heat-resistant, quick-drying polyether solvent adhesive according to claim 3, characterized in that: The small molecular weight polyacid of the polyester polyol in component A is one or both of adipic acid and terephthalic acid; The small molecule polyol is one or more of diethylene glycol, ethylene glycol, 1,4-butanediol, and neopentyl glycol; The antioxidant is triphenyl phosphite; The catalyst is tetra-n-butyl titanate.

5. The low-cost, heat-resistant, quick-drying polyether solvent adhesive according to claim 1 or 2, characterized in that: The isocyanate in the component A is toluene diisocyanate; The average molecular weight of the polyether polyol in the A component is 500-2000.

6. The low-cost, heat-resistant, quick-drying polyether solvent adhesive according to claim 1 or 2, characterized in that: The weight ratio of the isocyanate in the B component to the mixture of two polyether polyols with different molecular weights is 1:1-2; The isocyanate-terminated resin of component B is a product obtained by reacting isocyanate with a mixture of two polyether polyols with different molecular weights at 80-90° C., with an NCO value of 3-5%, a viscosity of 500-1000 mPa.s at 25° C., and a solid content of 50±5%.

7. The low-cost, heat-resistant, quick-drying polyether solvent adhesive according to claim 1 or 2, characterized in that: In the mixture of two polyether polyols of different molecular weights in component B, the average molecular weight of the low molecular weight polyether polyol is 500-2000, and the average molecular weight of the high molecular weight polyether polyol is 2000-4000; The isocyanate in the B component is one or more of diphenylmethane diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate.

8. A method for preparing the low-cost, temperature-resistant, quick-drying polyether solvent adhesive according to any one of claims 1 to 7, characterized in that: include: Prepare component A and component B separately, wherein: Preparation of component A: A mixture of polyol polyol and polyether polyol formed by mixing in a weight ratio of 1:2 to 4 is added to a container, ethyl acetate accounting for 20% of the total weight of the mixture of polyol polyol and polyether polyol is added and stirred evenly, and then isocyanate is added, and the mixture is heated to 80 to 90° C. and reacted for 3 to 5 hours. After cooling to below 50° C., ethyl acetate accounting for 20% of the total weight of the mixture of polyol polyol and polyether polyol is added and discharged, thereby obtaining component A; Preparation of component B: A mixture of two polyether polyols with different molecular weights formed by mixing a low molecular weight polyether polyol and a high molecular weight polyether polyol in a weight ratio of 4:1-2 is added to a container, ethyl acetate accounting for 25% of the total weight of the mixture of the two polyether polyols with different molecular weights is added and stirred evenly, and then isocyanate is added, and the mixture is heated to 80-90° C. and reacted for 3-5 hours, and the mixture is cooled to below 50° C. and ethyl acetate accounting for 25% of the total weight of the mixture of the two polyether polyols with different molecular weights is added and then discharged to obtain component B; Preparation of polyether solvent adhesive: After mixing the above-prepared component A and component B in a weight ratio of 1:0.8-1.2, add ethyl acetate to dilute to the required working solution concentration to obtain the polyether solvent adhesive.

9. The method for preparing the low-cost, heat-resistant, quick-drying polyether solvent adhesive according to claim 8, characterized in that: The polyester polyol in the A component is prepared in the following manner, including: The small molecule polyacid and the small molecule polyol are added into the polyester kettle in a weight ratio of 1:1 to 1.5, and then 500 ppm of antioxidant and 50 ppm of catalyst are added, and the polyester polyol is prepared by the commonly used esterification condensation method.

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