Binder used between plastic film and metal foil and preparation method thereof

Abstract

The invention discloses a binder used between a plastic film and a metal foil and a preparation method of the binder, and relates to the field of binders. The adhesive is prepared from the following raw materials in parts by weight: 30 to 50 parts of polyacrylate polyol, 20 to 40 parts of an aromatic isocyanate prepolymer, 5 to 10 parts of tackifying resin and 10 to 30 parts of a solvent, and the aromatic isocyanate prepolymer is an aromatic isocyanate prepolymer based on toluene diisocynate, diphenylmethane diisocyanate or naphthalene 1, 5-diisocyanate. The adhesive provided by the invention enhances the adhesion effect of materials with different interface polarities.

Description

Technical Field

[0001] The present invention relates to the field of adhesives, in particular to an adhesive used between a plastic film and a metal foil and a preparation method thereof. Background Art

[0002] The bond between plastic films and metal foils is important in many industrial applications, such as battery packaging films, food packaging, and insulation layers in electronic devices.

[0003] However, due to the large difference in surface polarity between plastic films (such as polyamides and polyolefins) and metal foils (such as aluminum foil), existing adhesives often have insufficient bonding effects between the two, especially in terms of moisture and heat resistance and mechanical strength. Summary of the Invention

[0004] The present invention has been made in view of the above-mentioned problems and provides an adhesive for use between a plastic film and a metal foil and a method for preparing the same.

[0005] The first aspect of the present invention provides an adhesive for use between a plastic film and a metal foil. The raw materials for preparing the adhesive include, in parts by weight, 30 to 50 parts of polyacrylate polyol, 20 to 40 parts of aromatic isocyanate prepolymer, 5 to 10 parts of tackifying resin, and 10 to 30 parts of solvent. The aromatic isocyanate prepolymer is an aromatic isocyanate prepolymer based on toluene diisocyanate, diphenylmethane diisocyanate, or naphthalene 1,5-diisocyanate.

[0006] In some embodiments of the present invention, the polyacrylate polyol has a hydroxyl value of 17-20 mg KOH / g and a weight average molecular weight of 40,000 to 100,000 g / mol.

[0007] In some embodiments of the present invention, the tackifying resin includes rosin resin and / or terpene resin.

[0008] In some embodiments of the present invention, the NCO functional group content of the aromatic isocyanate prepolymer is 17-20 wt %.

[0009] In some embodiments of the present invention, the binder includes 1 to 3 parts of a catalyst in parts by weight, and the catalyst includes dodecylbenzenesulfonic acid or DMP-30.

[0010] In some embodiments of the present invention, the solvent includes at least one of ethyl acetate, acetone, and triethylamine.

[0011] In some embodiments of the present invention, the auxiliary agent includes at least one of a leveling agent, a defoaming agent, and a light stabilizer.

[0012] A second aspect of the present invention provides a method for preparing the above-mentioned binder, comprising the following steps:

[0013] Under a protective atmosphere, n-butyl acrylate, hydroxyethyl methacrylate and an initiator are subjected to a free radical polymerization reaction in a solvent, and the reaction temperature and time are controlled to obtain a polyacrylate polyol with a target molecular weight; toluene diisocyanate is mixed with polyester polyol and trimethylolpropane to react to obtain an aromatic isocyanate prepolymer with a target NCO content; and the polyacrylate polyol, aromatic isocyanate prepolymer, tackifying resin, catalyst, additive and solvent are mixed in proportion and fully dispersed to obtain an adhesive for use between a plastic film and a metal foil.

[0014] In some embodiments of the present invention, the initiator comprises ammonium persulfate and azobisisobutyronitrile in a mass ratio of (1-2):1.

[0015] In some embodiments of the present invention, the reaction temperature of the free radical polymerization reaction is 70-78° C., and the reaction time is 4-6 hours.

[0016] In some embodiments of the present invention, the mixing reaction comprises adding trimethylolpropane three times, each time with an interval of 25 to 30 minutes, the reaction temperature is 65 to 75° C., and the reaction time is 3 to 5 hours.

[0017] The beneficial effects that can be achieved by the present invention are:

[0018] The present invention provides an adhesive for use between a plastic film and a metal foil. The polyacrylate polyol molecular chain contains both polar carboxylate groups and non-polar alkyl chain segments. An aromatic isocyanate prepolymer reacts with the polyacrylate polyol to form a cross-linked polyurethane network. A tackifying resin enhances the interaction between the molecular chains. A catalyst is used to precisely control the curing speed, ultimately forming a dense structure that can adhere to both metal and plastic, effectively overcoming the problem of adhesion failure caused by differences in interface polarity. DETAILED DESCRIPTION

[0019] The following description is provided to enable those skilled in the art to fully understand the present invention, and is not intended to limit the subject matter described in the claims.

[0020] The "ranges" disclosed herein are defined in terms of lower and upper limits, where a given range is defined by selecting a lower limit and an upper limit, and the selected lower and upper limits define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive of the end values and may be combined arbitrarily, i.e., any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if minimum range values of 1 and 2 are listed, and if maximum range values of 3, 4, and 5 are listed, the following ranges are all contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In the present invention, unless otherwise indicated, the numerical range "a to b" is a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0021] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0022] Unless otherwise specified, all technical features and optional technical features of the present invention can be combined with each other to form a new technical solution.

[0023] Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0024] The bond between plastic films and metal foils is important in many industrial applications, such as battery packaging films, food packaging, and insulation layers in electronic devices.

[0025] However, due to the large difference in surface polarity between plastic films (such as polyamides and polyolefins) and metal foils (such as aluminum foil), existing adhesives often have insufficient bonding effects between the two, especially in terms of moisture and heat resistance and mechanical strength.

[0026] In view of this, this proposal proposes an adhesive for use between a plastic film and a metal foil. The raw materials for preparing the adhesive, measured in parts by weight, include: 30 to 50 parts of polyacrylate polyol, 20 to 40 parts of aromatic isocyanate prepolymer, 5 to 10 parts of tackifying resin, and 10 to 30 parts of solvent. The aromatic isocyanate prepolymer is an aromatic isocyanate prepolymer based on toluene diisocyanate, diphenylmethane diisocyanate or naphthalene 1,5-diisocyanate.

[0027] Polyacrylate polyols can be obtained by copolymerizing hydroxyl-containing acrylate monomers (such as hydroxyethyl acrylate HEA or hydroxypropyl acrylate HPA) with other acrylate monomers (such as butyl acrylate, methyl methacrylate).

[0028] Polyacrylate polyol and aromatic isocyanate prepolymer form a polyurethane network through -NCO / -OH crosslinking reaction, providing high mechanical strength, and aromatic isocyanate gives the system excellent heat resistance and chemical stability.

[0029] The polyacrylate polyol molecular chain contains both polar carboxylate groups and non-polar alkyl segments, which synergize with the polar groups of the tackifying resin to further enhance the adhesive's adhesion and improve the interfacial wettability between the plastic film and the metal foil. The use of a catalyst accelerates the curing reaction, improving production efficiency while ensuring the adhesive forms a stable cross-linked structure within a short period of time.

[0030] This solution ultimately forms a dense structure that can adhere to metal and plastic respectively, effectively overcoming the adhesion failure problem caused by interfacial polarity differences.

[0031] In some embodiments, the raw materials for preparation preferably include, in parts by weight: 30-40 parts of polyacrylate polyol, 6-8 parts of tackifying resin, 25-35 parts of aromatic isocyanate prepolymer, 1-3 parts of catalyst, and 15-30 parts of solvent.

[0032] In some embodiments, the polyacrylate polyol has a hydroxyl value of 17-20 mg KOH / g and a weight-average molecular weight of 40,000 to 100,000 g / mol. Within this hydroxyl value range, the polyacrylate polyol can undergo a moderate crosslinking reaction with the aromatic isocyanate prepolymer. This moderate crosslinking provides sufficient bond strength while avoiding brittleness caused by excessive crosslinking. High-molecular-weight polyacrylate polyols have longer polymer chains, which can form good molecular entanglements within the crosslinked network, thereby imparting excellent flexibility and impact resistance to the adhesive.

[0033] In some embodiments, the tackifying resin includes rosin resin and / or terpene resin. Both have low viscosity, are easy to process and apply, and have good heat resistance and are suitable for high temperature environments.

[0034] In some embodiments, the aromatic isocyanate prepolymer has an -NCO functional group content of 17-20 wt%. The -NCO functional groups provide sufficient reactivity to undergo a cross-linking reaction with the hydroxyl groups in the polyacrylate polyol. A moderate -NCO content can regulate the curing reaction, improve the early strength of the adhesive, shorten the curing time, and thus improve production efficiency.

[0035] In some embodiments, the binder includes 1-3 parts by weight of a catalyst, including dodecylbenzenesulfonic acid or DMP-30. Dodecylbenzenesulfonic acid dynamically regulates the reaction rate, promoting the gradual polymerization of isocyanate prepolymers and polyols, forming a polyurethane network with a high crosslink density and uniform crosslink distribution, making it suitable for preparing a highly durable binder in normal storage conditions. The rigid benzene ring structure of DMP-30 can be embedded in the polyurethane backbone, enhancing the heat resistance and stability of the molecular chain, making it suitable for use in high-temperature environments.

[0036] In some embodiments, the solvent includes at least one of ethyl acetate, acetone, and triethylamine. Ethyl acetate and acetone, as medium-to-strong polar solvents, exhibit excellent solubility for polyacrylate polyols, tackifying resins, and isocyanate prepolymers. The amino group of triethylamine can weakly react with hydroxyl groups on the surface of the metal foil or aluminum oxide, enhancing interfacial affinity.

[0037] In some embodiments, the binder includes an additive, which includes at least one of a leveling agent, a defoaming agent, and a light stabilizer. The leveling agent is a silicone, such as polyether-modified polydimethylsiloxane BYK-333; the defoaming agent is a nonionic polyether-modified siloxane, such as polyether-siloxane copolymer BYK-022; and the light stabilizer is a benzotriazole, such as 2-(2H-benzotriazole-2-yl)-4,6-di-tert-amylphenol UV-328.

[0038] This solution proposes a method for preparing the above-mentioned adhesive between plastic film and metal foil, comprising the following steps:

[0039] Under a protective atmosphere, n-butyl acrylate, hydroxyethyl methacrylate, and an initiator are subjected to a free radical polymerization reaction in a solvent, with the reaction temperature and time controlled to obtain a polyacrylate polyol having a target molecular weight. In some embodiments, the mass ratio of n-butyl acrylate, hydroxyethyl methacrylate, and initiator is (4-6):1:0.03. In some embodiments, the initiator comprises ammonium persulfate and azobisisobutyronitrile in a mass ratio of (1-2):1.

[0040] Toluene diisocyanate is mixed with polyester polyol and trimethylolpropane to obtain an aromatic isocyanate prepolymer with a target -NCO content; trimethylolpropane is a trifunctional polyol that can react with -NCO groups to form urethane bonds -NHCOO-. In some embodiments, the mass ratio of toluene diisocyanate, polyester polyol and trimethylolpropane is 21: (60-75): 3, and polyester polyol is purchased from Kuraray P-2010.

[0041] The polyacrylate polyol, aromatic isocyanate prepolymer, tackifying resin, catalyst, auxiliary agent and solvent are mixed in proportion and fully dispersed to obtain an adhesive used between a plastic film and a metal foil.

[0042] In some embodiments, the proportions, in parts by weight, are 30-50 parts of polyacrylate polyol, 5-10 parts of tackifying resin, 20-40 parts of aromatic isocyanate prepolymer, 1-3 parts of catalyst, 10-30 parts of solvent, 0.3-5 parts of leveling agent, 0.3-5 parts of defoaming agent, and 0-5 parts of light stabilizer.

[0043] In some embodiments, the post-mixing dispersion includes pre-mixing polyacrylate polyol, tackifying resin, and solvent at 50° C., adding aromatic isocyanate, and dispersing at a high speed of 2000 rpm for 15 minutes, simultaneously injecting a catalyst, a leveling agent, and a defoaming agent, and filtering through a 5 μm filter element to obtain an adhesive for use between a plastic film and a metal foil.

[0044] In some embodiments, the free radical polymerization reaction temperature is 70-78°C and the reaction time is 4-6 hours. During the initiation phase, 0.2 parts of ammonium persulfate initiator are added, and the temperature is raised to 78°C under nitrogen to initiate polymerization. After 2 hours of reaction, 0.1 parts of azobisisobutyronitrile solution is added, and the temperature is maintained at 75±0.5°C to control chain growth and hydroxyl value.

[0045] In some embodiments, the mixing reaction comprises adding trimethylolpropane three times, each time with an interval of 25 to 30 minutes, the reaction temperature is 65 to 75° C., the reaction time is 3 to 5 hours, and the stirring speed during the mixing reaction is 400 to 700 rpm.

[0046] The above preparation method can efficiently obtain a target adhesive that quickly reacts on the surface to generate a dense cross-linked area and retains moderately flexible chain segments inside through the coordinated regulation of raw material ratio and reaction kinetics, thereby achieving stable adhesion between plastic film and metal foil.

[0047] The technical solutions of the present invention are further described in detail below in conjunction with specific embodiments. It should be understood that the following specific embodiments are only used to explain the present invention and are not used to limit the present invention.

[0048] Example 1

[0049] In parts by weight, 40 parts of n-butyl acrylate, 10 parts of hydroxyethyl methacrylate and an initiator were subjected to a free radical polymerization reaction in a solvent under a protective atmosphere. 0.2 parts of ammonium persulfate initiator was added during the initiation stage. The polymerization was initiated by heating to 78° C. under nitrogen protection. After reacting for 2 hours, 0.1 parts of azobisisobutyronitrile was added. The temperature was maintained at 75±0.5° C. and the reaction was continued for 2 hours to obtain a polyacrylate polyol having a hydroxyl value of 17 mg KOH / g and a weight average molecular weight of 54,000 g / mol.

[0050] 21 parts of toluene diisocyanate were mixed with 66 parts of polyester polyol and 3 parts of trimethylolpropane for reaction, and the trimethylolpropane was added in three portions, 1 part each time, with an interval of 30 minutes. The reaction temperature was 70±0.5°C, the stirring speed was 500 rpm, and the total reaction time was 5 hours to obtain an aromatic isocyanate prepolymer with an -NCO content of 17 wt%;

[0051] 45 parts of polyacrylate polyol, 5 parts of rosin resin, and 20 parts of ethyl acetate were premixed at 50°C. After adding 40 parts of aromatic isocyanate prepolymer, the mixture was dispersed at 2000 rpm for 15 minutes. 0.3 parts of DMP-30, 0.3 parts of BYK-333, 0.3 parts of BYK-022, and 0.1 parts of UV-328 were simultaneously injected. The mixture was filtered through a 5 μm filter to obtain an adhesive for use between plastic film and metal foil.

[0052] Example 2

[0053] In parts by weight, 35 parts of n-butyl acrylate, 15 parts of hydroxyethyl methacrylate and an initiator were subjected to a free radical polymerization reaction in a solvent under a protective atmosphere. 0.2 parts of ammonium persulfate initiator was added during the initiation stage. The polymerization was initiated by heating to 78° C. under nitrogen protection. After reacting for 2 hours, 0.1 parts of azobisisobutyronitrile was added. The temperature was maintained at 73±0.5° C. and the reaction was continued for 2 hours to obtain a polyacrylate polyol having a hydroxyl value of 19 mg KOH / g and a weight-average molecular weight of 40,000 g / mol.

[0054] 21 parts of toluene diisocyanate were mixed with 70 parts of polyester polyol and 3 parts of trimethylolpropane for reaction, and the trimethylolpropane was added in three portions, 1 part each time, with an interval of 30 minutes. The reaction temperature was 70±0.5°C, the stirring speed was 500 rpm, and the total reaction time was 5 hours to obtain an aromatic isocyanate prepolymer with an -NCO content of 19 wt%;

[0055] 40 parts of polyacrylate polyol, 5 parts of rosin resin, and 20 parts of ethyl acetate were premixed at 50°C. After adding 40 parts of aromatic isocyanate prepolymer, the mixture was dispersed at 2000 rpm for 15 minutes. 0.3 parts of DMP-30, 0.3 parts of BYK-333, 0.3 parts of BYK-022, and 0.1 parts of UV-328 were simultaneously injected. The mixture was filtered through a 5 μm filter to obtain an adhesive for use between plastic film and metal foil.

[0056] Example 3

[0057] In parts by weight, 40 parts of n-butyl acrylate, 10 parts of hydroxyethyl methacrylate and an initiator were subjected to a free radical polymerization reaction in a solvent under a protective atmosphere. 0.2 parts of ammonium persulfate initiator was added during the initiation stage. The polymerization was initiated by heating to 78° C. under nitrogen protection. After reacting for 2 hours, 0.1 parts of azobisisobutyronitrile was added. The temperature was maintained at 75±0.5° C. and the reaction was continued for 2 hours to obtain a polyacrylate polyol having a hydroxyl value of 19 mg KOH / g and a weight average molecular weight of 67,000 g / mol.

[0058] 21 parts of toluene diisocyanate were mixed with 75 parts of polyester polyol and 3 parts of trimethylolpropane for reaction, and the trimethylolpropane was added in three portions, 1 part each time, with an interval of 30 minutes. The reaction temperature was 70±0.5°C, the stirring speed was 500 rpm, and the total reaction time was 5 hours to obtain an aromatic isocyanate prepolymer with an -NCO content of 19 wt%;

[0059] 35 parts of polyacrylate polyol, 5 parts of rosin resin, and 20 parts of ethyl acetate were premixed at 50°C. After adding 35 parts of aromatic isocyanate prepolymer, the mixture was dispersed at 2000 rpm for 15 minutes. 0.3 parts of DMP-30, 0.3 parts of BYK-333, 0.3 parts of BYK-022, and 0.1 parts of UV-328 were simultaneously injected. The mixture was filtered through a 5 μm filter to obtain an adhesive for use between plastic film and metal foil.

[0060] Example 4

[0061] In parts by weight, 50 parts of n-butyl acrylate, 10 parts of hydroxyethyl methacrylate and an initiator were subjected to a free radical polymerization reaction in a solvent under a protective atmosphere. 0.15 parts of ammonium persulfate initiator was added during the initiation stage. The polymerization was initiated by heating to 78° C. under nitrogen protection. After reacting for 2 hours, 0.15 parts of azobisisobutyronitrile was added. The temperature was maintained at 75±0.5° C. and the reaction was continued for 2 hours to obtain a polyacrylate polyol having a hydroxyl value of 17 mg KOH / g and a weight average molecular weight of 66,300 g / mol.

[0062] 21 parts of diphenylmethane diisocyanate were mixed with 60 parts of polyester polyol and 3 parts of trimethylolpropane, and the trimethylolpropane was added in three portions, 1 part each time, with an interval of 30 minutes. The reaction temperature was 70±0.5°C, the stirring speed was 500 rpm, and the total reaction time was 5 hours to obtain an aromatic isocyanate prepolymer with an -NCO content of 17 wt%;

[0063] 50 parts of polyacrylate polyol, 10 parts of rosin resin, and 30 parts of ethyl acetate were premixed at 50°C, and 40 parts of aromatic isocyanate prepolymer were added. The mixture was dispersed at 2000 rpm for 15 minutes. 0.3 parts of DMP-30, 0.3 parts of BYK-333, 0.3 parts of BYK-022, and 0.1 parts of UV-328 were simultaneously injected. The mixture was filtered through a 5 μm filter to obtain an adhesive for use between plastic film and metal foil.

[0064] Comparative Example 1

[0065] 50 parts of polyacrylate polyol, 5 parts of rosin resin, and 20 parts of ethyl acetate were premixed at 50°C, and 45 parts of aromatic isocyanate prepolymer were added. The mixture was dispersed at 2000 rpm for 15 minutes. 0.3 parts of DMP-30, 0.3 parts of BYK-333, 0.3 parts of BYK-022, and 0.1 parts of UV-328 were simultaneously injected. The mixture was filtered through a 5 μm filter to obtain an adhesive for use between a plastic film and a metal foil. For other reasons, refer to Example 1.

[0066] Comparative Example 2

[0067] 30 parts of polyacrylate polyol, 5 parts of rosin resin, and 20 parts of ethyl acetate were premixed at 50°C. After adding 35 parts of aromatic isocyanate prepolymer, the mixture was dispersed at 2000 rpm for 15 minutes. 0.3 parts of DMP-30, 0.3 parts of BYK-333, 0.3 parts of BYK-022, and 0.1 parts of UV-328 were simultaneously injected. The mixture was filtered through a 5 μm filter cartridge to obtain an adhesive for use between a plastic film and a metal foil. For other reasons, refer to Example 1.

[0068] Comparative Example 3

[0069] The hydroxyl value of the polyacrylate polyol is 12 mg KOH / g, the -NCO functional group content of the aromatic isocyanate prepolymer is 12 wt %, and the initiator is 0.3 parts of azobisisobutyronitrile as a single initiator. Other details are as in Example 1.

[0070] Performance testing:

[0071] The adhesives used between plastic film and metal foil obtained in the examples and comparative examples were tested. The test contents included:

[0072] 1. Adhesive properties:

[0073] The adhesive was cast into a film on a polytetrafluoroethylene plate, left to stand at room temperature for a period of time, and then placed in an oven and baked at 50°C for 4 to 6 hours to prepare a film with a thickness of about 1 mm:

[0074] 1. Determination of shear strength

[0075] The tensile shear strength test was performed using an LJ-1000 tensile testing machine with a fixture movement speed of 10 mm / min.

[0076] 2. Determination of elongation at break

[0077] The elongation at break was measured using an INSTROK 4302 tensile testing machine.

[0078] 3. Determination of water absorption

[0079] Weigh the film with a weight of W1, immerse it in deionized water, take it out after 5 days, wipe off the surface water with filter paper, and weigh it as W2. The water absorption rate can be calculated using the following formula: Water absorption rate (%) = [(W2-W1) / W1]×100%.

[0080] 2. Application performance of adhesive

[0081] Use a wire rod coater to evenly apply glue between a 12μm PET film and a 40μm aluminum foil, cure at 80℃ for 2h, and achieve a dry glue thickness of 8μm. Then perform hot pressing and lamination to obtain the sample to be tested:

[0082] 1. Initial peel strength (N / cm), 180° peel test, refer to GBT2792-2014;

[0083] 2. Moisture and heat resistance: Test aging retention rate (%) at 90%±5%RH, 185℃, 28 days.

[0084] The results are recorded in Table 1:

[0085] Table 1: Test results of Examples 1 to 6 and Comparative Examples 1 to 3

[0086]

[0087]

[0088] The adhesive strength and toughness of Examples 1-4 are relatively balanced, reflecting the stability of the cross-linked network. Comparative Examples 1 / 2 verify that the ratio of the main resin and the curing agent deviates from the optimal value, resulting in performance imbalance. Comparative Example 3 has a low hydroxyl value and low -NCO and uses a single initiator (azobisisobutyronitrile), which may result in poor segment regularity, loss of control of the molecular weight distribution by segmented polymerization, and cross-linked network defects, resulting in the worst interface adhesion.

[0089] It can be seen that in the adhesive for use between plastic film and metal foil provided by this solution, the polyacrylate polyol molecular chain contains both polar carboxylate groups and non-polar alkyl chain segments, the aromatic isocyanate prepolymer reacts with the polyacrylate polyol to form a cross-linked polyurethane network, the tackifying resin enhances the interaction between the molecular chains, and the catalyst is used to precisely control the curing speed, ultimately forming a dense structure that can form adhesion to metal and plastic respectively, effectively overcoming the problem of adhesion failure caused by interfacial polarity differences.

[0090] It should be noted that the present invention is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the technical solution of the present invention are all included in the technical scope of the present invention. In addition, without departing from the scope of the present invention, other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present invention.

Claims

1. An adhesive for use between a plastic film and a metal foil, characterized in that: The raw materials for preparing the binder include, in parts by weight: 30-50 parts of polyacrylate polyol, 20-40 parts of aromatic isocyanate prepolymer, 5-10 parts of tackifying resin, 10 to 30 parts of solvent, The aromatic isocyanate prepolymer is an aromatic isocyanate prepolymer based on toluene diisocyanate, diphenylmethane diisocyanate or naphthalene 1,5-diisocyanate.

2. The adhesive for use between a plastic film and a metal foil according to claim 1, characterized in that: The hydroxyl value of the polyacrylate polyol is 17 to 20 mg KOH / g, and the weight average molecular weight of the polyacrylate polyol is 40,000 to 100,000 g / mol.

3. The adhesive for use between a plastic film and a metal foil according to claim 1, characterized in that: The tackifying resin includes rosin resin and / or terpene resin.

4. The adhesive for use between a plastic film and a metal foil according to claim 1, characterized in that: The -NCO functional group content of the aromatic isocyanate prepolymer is 17-20 wt %.

5. The adhesive for use between a plastic film and a metal foil according to claim 1, characterized in that: In parts by weight, the binder includes 1 to 3 parts of a catalyst, and the catalyst includes dodecylbenzenesulfonic acid or DMP-30.

6. The adhesive for use between a plastic film and a metal foil according to claim 1, characterized in that: The solvent includes at least one of ethyl acetate, acetone, and triethylamine.

7. A method for preparing an adhesive for use between a plastic film and a metal foil as claimed in any one of claims 1 to 6, characterized in that: The following steps are involved: Under a protective atmosphere, n-butyl acrylate, hydroxyethyl methacrylate and an initiator are subjected to a free radical polymerization reaction in a solvent, and the reaction temperature and time are controlled to obtain a polyacrylate polyol with a target molecular weight; Toluene diisocyanate is mixed with polyester polyol and trimethylolpropane to react to obtain an aromatic isocyanate prepolymer with a target -NCO content; The polyacrylate polyol, aromatic isocyanate prepolymer, tackifying resin, catalyst, auxiliary agent and solvent are mixed in proportion and fully dispersed to obtain an adhesive used between a plastic film and a metal foil.

8. The method for preparing an adhesive for use between a plastic film and a metal foil according to claim 7, wherein: The initiator comprises two initiators, ammonium persulfate and azobisisobutyronitrile, in a mass ratio of (1-2):

1.

9. The method for preparing an adhesive for use between a plastic film and a metal foil according to claim 7, wherein: The reaction temperature of the free radical polymerization reaction is 70-78° C., and the reaction time is 4-6 hours.

10. The method for preparing an adhesive between a plastic film and a metal foil according to claim 7, characterized in that: The mixing reaction comprises adding trimethylolpropane three times, each time with an interval of 25 to 30 minutes, the reaction temperature is 65 to 75° C., and the reaction time is 3 to 5 hours.

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