Environment-friendly water-based composite adhesive for transfer paper and preparation method thereof

Abstract

The application discloses an environment-friendly water-based composite adhesive for transfer paper and a preparation method thereof. Raw materials are prepared according to the following mass percentages: 28-45% of methyl methacrylate; 30-40% of butyl acrylate; 0.3-0.8% of an initiator; 2-4% of an emulsifier; 1-5% of butadiene; 0.5-1.5% of a tackifier; 0-0.15% of a reinforcing agent; 0.1-0.5% of a pH regulator; 0.05-0.25% of a defoaming agent; and the balance of water. The preparation process comprises the following steps: S1, butadiene prepolymerization; S2, preparation of an acrylate emulsion; and S3, mixing and blending. The butadiene, the tackifier and the reinforcing agent are used in the formula to regulate the adhesive force and the toughness of the adhesive film, the types of acrylate monomers are reduced, and the defects of limited regulation capacity, many variables and difficulty in simultaneous consideration when the above parameters are regulated by accurately controlling the types and contents of acrylate soft and hard monomers are overcome.

Description

Technical Field

[0001] This invention belongs to the field of adhesive technology, specifically relating to an environmentally friendly water-based composite adhesive for transfer paper and its preparation method. Background Technology

[0002] Water-based composite adhesives are environmentally friendly adhesives that use water as the main solvent or dispersant, and can replace traditional organic solvent-based adhesives. Currently, the main water-based composite adhesives used in the printing and packaging industry are VAE emulsions, styrene-butadiene emulsions, and acrylic emulsions. VAE emulsions have drawbacks such as relatively insufficient adhesion, poor low-temperature resistance, slow drying speed, and high cost. Styrene-butadiene emulsions mainly suffer from the release of harmful substances such as styrene during production and use. Therefore, acrylic emulsions are currently the most widely used water-based composite adhesive product on the market.

[0003] Transfer paper has wide applications in printing and packaging, especially in mid-to-high-end tobacco and alcohol packaging boxes, where it often features a metallic sheen. Currently, the production process of metallized transfer paper involves using a water-based composite adhesive to bond the metallized layer to the transfer paper, and then transferring a PET or BOPP film, after the metallized layer is peeled off, to the substrate. If the adhesive strength of the water-based composite adhesive is insufficient or the resulting film lacks flexibility, the substrate may peel off some of the aluminum layer from the transfer paper during production. Furthermore, when the metallized transfer paper is repeatedly folded, significant separation or cracking of the aluminum layer at the fold lines can easily occur. The conventional approach to solving these problems in existing technologies is to select various soft and hard monomers and precisely control their proportions. By adjusting the adhesive strength and flexibility of the water-based composite adhesive, these problems can be addressed to some extent. However, due to the large number of soft and hard monomers used and the need for precise proportion control, the production process is quite difficult. Additionally, it is challenging to simultaneously achieve both adhesive strength and flexibility simply by adjusting the types and amounts of soft and hard monomers. Summary of the Invention

[0004] This invention provides an environmentally friendly water-based composite adhesive for transfer paper and its preparation method, aiming to overcome the above-mentioned problems existing in the prior art when conventionally composed acrylate emulsions are used as water-based composite adhesives for metallized transfer paper.

[0005] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A method for preparing an environmentally friendly water-based composite adhesive for transfer paper, which requires preparing the raw materials according to the following mass percentages:

[0006] Methyl methacrylate 28-45%; butyl acrylate 30-40%; initiator 0.3-0.8%; emulsifier 2-4%; butadiene 1-5%; thickener 0.5-1.5%; reinforcing agent 0-0.15%; pH adjuster 0.1-0.5%; defoamer 0.05-0.25%, balance being deionized water;

[0007] The preparation process includes the following steps:

[0008] S1. Butadiene prepolymerization: Mix 20-30% of the emulsifier and 15-25% of the deionized water in the above ratio, stir evenly, and then add all the butadiene. Continue stirring during the addition process to obtain the first emulsion. Take an appropriate amount of deionized water to dissolve the initiator to form an initiator solution. Then add 10-30% of the initiator solution dropwise to the first emulsion, heat and stir to carry out the polymerization reaction. After the polymerization is completed, the first mixture is obtained and set aside.

[0009] S2. Preparation of acrylate emulsion: Mix the remaining emulsifier and deionized water. After stirring evenly, add all of the methyl methacrylate, butyl acrylate and thickener. Continue stirring during the addition process to obtain the second emulsion. Take 10-30% of the second emulsion and place it in a reactor. Add 40-50% of the remaining initiator solution dropwise. After the dropwise addition is complete, heat and stir to carry out the polymerization reaction for 1-2 hours. Then add all of the remaining second emulsion to the reactor, and at the same time add 65-75% of the remaining initiator solution dropwise. After the dropwise addition is complete, heat and stir to react for 2-3 hours. After the reaction is complete, add the reinforcing agent according to the ratio and stir evenly to obtain the second mixture for later use.

[0010] S3. Mixing and blending: Mix mixture one and mixture two, add all the remaining initiator, heat and stir until well mixed, keep warm for 20-30 minutes, then add pH adjuster and defoamer, mix well, filter, and the environmentally friendly water-based composite adhesive is obtained.

[0011] Based on the above technical solution, the present invention can also make the following further specific choices or better choices.

[0012] Specifically, the tackifier is composed of a silane coupling agent and hydroxyethyl methacrylate phosphate (HEMAP phosphate), wherein the mass percentage of the silane coupling agent (preferably KH570) is 0.1-0.5%, and the mass percentage of the hydroxyethyl methacrylate phosphate is 0.3-1.2%.

[0013] Preferably, the mass ratio of the silane coupling agent to hydroxyethyl methacrylate phosphate in the tackifier is 1:(1-5).

[0014] Specifically, the emulsifier is octylphenol polyoxyethylene ether (OP-10) or sodium alkyl sulfonate.

[0015] Specifically, the initiator is ammonium persulfate, sodium persulfate, or potassium persulfate.

[0016] Specifically, the reinforcing agent is cellulose nanocrystals or nano-silica.

[0017] Specifically, the pH adjuster is sodium hydroxide or concentrated ammonia.

[0018] Specifically, the defoamer is a mineral oil defoamer or a modified organosilicon defoamer.

[0019] Specifically, the reaction temperature for heating and stirring polymerization in S1 is controlled at 45-50℃, the reaction temperature for heating and stirring in S2 is controlled at 80-85℃, and the temperature for heating and stirring mixing in S3 is controlled at 70-80℃. Preferably, the stirring speed is controlled at 120-240 r / min during mixing and reaction.

[0020] The present invention also provides an environmentally friendly water-based composite adhesive for transfer paper, which is prepared by the above method.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] This invention effectively controls adhesive strength and film toughness by adding butadiene, tackifiers, and reinforcing agents to the raw materials of an environmentally friendly water-based composite adhesive formulation. This reduces the types of acrylate monomers, avoiding the limitations of traditional methods that rely on precise control of the types and amounts of soft and hard acrylate monomers to regulate these parameters. The resulting environmentally friendly water-based composite adhesive exhibits excellent adhesion to the aluminized layer and transfer paper substrate. When peeling off the aluminized layer from PET or BOPP films onto the transfer substrate, no aluminum falls off or leaks, ensuring complete transfer of the aluminized layer to the transfer paper. Simultaneously, the adhesive film exhibits moderate toughness and strength, good folding resistance, and no separation or detachment of the aluminized film from the transfer paper is observed after repeated folding.

[0023] In the waterborne composite adhesive preparation method provided by this invention, butadiene is first prepolymerized to form a polybutadiene-containing mixture one. Then, methyl methacrylate, butyl acrylate, and a tackifier are used to prepare a polyacrylate-containing mixture two. Finally, mixture one and mixture two are mixed and a micro-polymerization reaction is initiated again. The polybutadiene in the final waterborne composite adhesive plays a role in toughening and enhancing film-forming properties, significantly improving the toughness of the waterborne composite adhesive after film formation. In addition, the silane coupling agent and hydroxyethyl methacrylate phosphate in the tackifier are combined in a specific ratio, which can significantly improve the adhesion of the waterborne composite adhesive to transfer paper and metal aluminum film with a small amount. The reinforcing agent can further enhance the strength of the adhesive film. In actual use, it can be flexibly added according to the strength and stiffness requirements of the metallized transfer paper, enriching the functionality of the composite adhesive. Detailed Implementation

[0024] The technical solutions provided by the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] To avoid unnecessary details, unless otherwise specified, all pharmaceutical raw materials used in the following examples are commercially available products, and all methods used are conventional methods in the art.

[0026] Example 1

[0027] An environmentally friendly water-based composite adhesive for transfer paper is prepared as follows:

[0028] Prepare each raw material according to the following mass percentages:

[0029] Methyl methacrylate 28%; butyl acrylate 30%; ammonium persulfate 0.3%; octylphenol polyoxyethylene ether 2%; butadiene 1%; silane coupling agent 0.1%; hydroxyethyl methacrylate phosphate 0.5%; sodium hydroxide 0.1%; mineral oil defoamer (Rhodoline DF 5800C) 0.08%, balance deionized water;

[0030] The preparation process includes the following steps:

[0031] S1. Butadiene prepolymerization: Mix 20% of the emulsifier and 15% of the deionized water in the above ratio, stir evenly, and then add all the butadiene. Stir continuously during the addition process to obtain the first emulsion. Take an appropriate amount of deionized water to dissolve the initiator to form an ammonium persulfate solution (concentration 10wt%). Then add 10% of the ammonium persulfate solution dropwise to the first emulsion, heat and stir to carry out the polymerization reaction. The reaction temperature is controlled at 50℃ and the reaction time is 3h. After the reaction is completed, cool to room temperature to obtain the first mixture for later use.

[0032] S2. Preparation of acrylate emulsion: Mix the remaining emulsifier and deionized water. After stirring evenly, add all of the methyl methacrylate, butyl acrylate, silane coupling agent and hydroxyethyl methacrylate phosphate. Stir continuously during the addition process. Mix evenly to obtain the second emulsion. Take 10% of the second emulsion and place it in the reactor. Add 40% of the remaining ammonium persulfate solution dropwise. After the dropwise addition is complete, heat and stir to carry out the polymerization reaction. Control the reaction temperature at 80℃ and react for 1 hour. Then add all of the remaining second emulsion to the reactor. At the same time, add 65% of the remaining ammonium persulfate solution (the remaining ammonium persulfate solution after the first two drops, the same below) dropwise. After the dropwise addition is complete, heat and stir to react. Control the reaction temperature at 80℃ and react for 2 hours. After the reaction is complete, stir evenly to obtain the second mixture for later use.

[0033] S3. Mixing and preparation: Mix mixture one and mixture two, add the remaining amount of ammonium persulfate solution, heat and stir until well mixed, control the temperature of the mixture at 70℃ after heating, keep it at this temperature for 20 minutes, then add sodium hydroxide and mineral oil defoamer (Rhodoline DF 5800C), mix well, filter, and the environmentally friendly water-based composite adhesive is obtained.

[0034] Example 2

[0035] An environmentally friendly water-based composite adhesive for transfer paper is prepared as follows:

[0036] Prepare each raw material according to the following mass percentages:

[0037] Methyl methacrylate 40%; butyl acrylate 35%; ammonium persulfate 0.5%; octylphenol polyoxyethylene ether 3%; butadiene 4%; silane coupling agent 0.4%; hydroxyethyl methacrylate phosphate 0.8%; sodium hydroxide 0.3%; mineral oil defoamer (Rhodoline DF 5800C) 0.1%, balance deionized water;

[0038] The preparation process includes the following steps:

[0039] S1. Butadiene prepolymerization: Mix 24% of the emulsifier and 20% of the deionized water in the above ratio, stir evenly, and then add all the butadiene. Stir continuously during the addition process to obtain the first emulsion. Take an appropriate amount of deionized water to dissolve the initiator to form an ammonium persulfate solution (concentration 10wt%). Then, add 20% of the ammonium persulfate solution dropwise to the first emulsion, heat and stir to carry out the polymerization reaction. The reaction temperature is controlled at 50℃ and the reaction time is 4h. After the reaction is completed, cool to room temperature to obtain the first mixture for later use.

[0040] S2. Preparation of acrylate emulsion: Mix the remaining emulsifier and deionized water. After stirring evenly, add all of the methyl methacrylate, butyl acrylate, silane coupling agent and hydroxyethyl methacrylate phosphate. Stir continuously during the addition process. Mix well to obtain the second emulsion. Take 20% of the second emulsion and place it in a reaction vessel. Add 45% of the remaining ammonium persulfate solution dropwise. After the dropwise addition is complete, heat and stir to carry out the polymerization reaction. Control the reaction temperature at 80℃ and react for 2 hours. Then add all of the remaining second emulsion to the reaction vessel. At the same time, add 70% of the remaining ammonium persulfate solution dropwise. After the dropwise addition is complete, heat and stir to carry out the reaction. Control the reaction temperature at 80℃ and react for 3 hours. After the reaction is complete, stir evenly to obtain the second mixture for later use.

[0041] S3. Mixing and preparation: Mix mixture one and mixture two, add the remaining amount of ammonium persulfate solution, heat and stir until well mixed. After heating, control the temperature of the mixture to 70℃ and keep it warm for 30 minutes. Then add sodium hydroxide and mineral oil defoamer (Rhodoline DF 5800C), mix well, filter, and the environmentally friendly water-based composite adhesive is obtained.

[0042] Example 3

[0043] An environmentally friendly water-based composite adhesive for transfer paper is prepared as follows:

[0044] Prepare each raw material according to the following mass percentages:

[0045] Methyl methacrylate 45%; butyl acrylate 30%; ammonium persulfate 0.6%; octylphenol polyoxyethylene ether 4%; butadiene 5%; silane coupling agent 0.5%; hydroxyethyl methacrylate phosphate 0.5%; sodium hydroxide 0.5%; mineral oil defoamer (Rhodoline DF 5800C) 0.25%, balance deionized water;

[0046] The preparation process includes the following steps:

[0047] S1. Butadiene prepolymerization: Mix 30% of the emulsifier and 25% of the deionized water in the above ratio, stir evenly, and then add all the butadiene. Continue stirring during the addition process to obtain the first emulsion. Take an appropriate amount of deionized water to dissolve the initiator to form an ammonium persulfate solution (concentration 10wt%). Then, add 30% of the ammonium persulfate solution dropwise to the first emulsion, heat and stir to carry out the polymerization reaction. The reaction temperature is controlled at 50℃ and the reaction time is 4h. After the reaction is completed, cool to room temperature to obtain the first mixture for later use.

[0048] S2. Preparation of acrylate emulsion: Mix the remaining emulsifier and deionized water. After stirring evenly, add all of the methyl methacrylate, butyl acrylate, silane coupling agent and hydroxyethyl methacrylate phosphate. Stir continuously during the addition process. Mix evenly to obtain the second emulsion. Take 30% of the second emulsion and place it in a reaction vessel. Add 50% of the remaining ammonium persulfate solution dropwise. After the dropwise addition is complete, heat and stir to carry out the polymerization reaction. Control the reaction temperature at 80℃ and react for 2 hours. Then add all of the remaining second emulsion to the reaction vessel. At the same time, add 75% of the remaining ammonium persulfate solution dropwise. After the dropwise addition is complete, heat and stir to carry out the reaction. Control the reaction temperature at 80℃ and react for 3 hours. After the reaction is complete, stir evenly to obtain the second mixture for later use.

[0049] S3. Mixing and preparation: Mix mixture one and mixture two, add the remaining amount of ammonium persulfate solution, heat and stir until well mixed. After heating, control the temperature of the mixture to 70℃ and keep it warm for 30 minutes. Then add sodium hydroxide and mineral oil defoamer (Rhodoline DF 5800C), mix well, filter, and the environmentally friendly water-based composite adhesive is obtained.

[0050] Example 4

[0051] Compared with Example 1, this example uses a reinforcing agent (cellulose nanocrystals) as one of the formulation raw materials, with a corresponding mass percentage of 0.1% in the formulation raw materials. It is added to the acrylate emulsion obtained after the S2 reaction is completed and stirred evenly. Other contents are consistent with Example 1.

[0052] Comparative Example 1

[0053] Compared with Example 2, no butadiene raw material was used in this comparative example, and the corresponding preparation method did not involve prepolymerization and subsequent mixing of butadiene. The water-based composite adhesive was prepared according to the conventional preparation method of acrylate emulsion.

[0054] Comparative Example 2

[0055] No silane coupling agent was used in this comparative example; all other aspects are consistent with Example 2.

[0056] Comparative Example 3

[0057] Hydroxyethyl methacrylate phosphate was not used in this comparative example; all other aspects remained the same as in Example 2.

[0058] Comparative Example 4

[0059] Hydroxyethyl methacrylate phosphate was not used in this comparative example, but the amount of silane coupling agent was increased to 0.8%, and the rest was the same as in Example 2.

[0060] Comparative Example 5

[0061] In this comparative example, no silane coupling agent was used, but the amount of hydroxyethyl methacrylate phosphate was increased to 1.6%, and the rest was the same as in Example 2.

[0062] The environmentally friendly water-based composite adhesives prepared in Examples 1 to 4 of this invention are all relatively stable and uniform emulsions. They are applied at the same amount (approximately 5-6 g / m³). 2 The same batch of transfer paper was sizing, and then the PET with an aluminum film layer was laminated to the transfer paper. Multiple sets of tests were conducted in parallel. During lamination, the aluminum film layer adhered to the sizing surface of the transfer paper. After complete adhesion, the PET film was peeled off, and the aluminum film layer was completely transferred to the transfer paper without any leaks or aluminum loss, resulting in high-quality aluminum-coated transfer paper. The aluminum-coated transfer paper corresponding to Example 1 was generally soft and lacked stiffness, but after adding a reinforcing agent in Example 4, the paper strength and stiffness were significantly improved. When peeling off the PET film, no aluminum loss or leaks were observed. The aluminum-coated transfer paper was repeatedly folded along the same fold line more than 20 times without any separation or cracking of the aluminum film layer from the transfer paper, indicating good adhesion and film toughness.

[0063] Except for Comparative Example 4, which had an uneven emulsion due to a large amount of silane coupling agent, the other comparative examples yielded uniform emulsions. Using the same method, the water-based composite adhesives obtained from the comparative examples (excluding Comparative Example 4) were used to prepare aluminized transfer paper. The aluminized transfer papers prepared in Comparative Examples 1 to 3 and Comparative Example 5 showed varying degrees of aluminum shedding or leakage during parallel multi-group tests, indicating insufficient adhesive strength. Furthermore, when the aluminized transfer paper was repeatedly folded, the aluminized layer easily separated from the transfer paper at the fold lines, causing tearing and white leakage. Comparative Examples 1 to 3 were more prone to this problem and the severity was greater. Although Comparative Example 5 showed some improvement compared to Comparative Examples 1 to 3, the separation and tearing problem was still quite noticeable.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an environmentally friendly water-based composite adhesive for transfer paper, characterized in that, Prepare each raw material according to the following mass percentages: The composition includes: methyl methacrylate 28-45%; butyl acrylate 30-40%; initiator 0.3-0.8%; emulsifier 2-4%; butadiene 1-5%; tackifier 0.5-1.5%; reinforcing agent 0-0.15%; pH adjuster 0.1-0.5%; defoamer 0.05-0.25%, with the balance being deionized water; the tackifier is composed of a silane coupling agent and hydroxyethyl methacrylate phosphate, with the silane coupling agent accounting for 0.1-0.5% by mass and the hydroxyethyl methacrylate phosphate accounting for 0.3-1.2% by mass; the mass ratio of the silane coupling agent to the hydroxyethyl methacrylate phosphate in the tackifier is 1:(1-5); the reinforcing agent is cellulose nanocrystals or nano-silica; The preparation process includes the following steps: S1. Butadiene prepolymerization: Mix 20-30% of the emulsifier and 15-25% of the deionized water in the above ratio, stir evenly, and then add all the butadiene. Continue stirring during the addition process to obtain the first emulsion. Take an appropriate amount of deionized water to dissolve the initiator to form an initiator solution. Then add 10-30% of the initiator solution dropwise to the first emulsion, heat and stir to carry out the polymerization reaction. After the polymerization is completed, the first mixture is obtained and set aside. S2. Preparation of acrylate emulsion: Mix the remaining emulsifier and deionized water. After stirring evenly, add all of the methyl methacrylate, butyl acrylate and thickener. Continue stirring during the addition process to obtain a second emulsion. Take 10-30% of the second emulsion and place it in a reactor. Add 40-50% of the remaining initiator solution dropwise. After the dropwise addition is complete, heat and stir to carry out the polymerization reaction for 1-2 hours. Then add all of the remaining second emulsion to the reactor, and at the same time add 65-75% of the remaining initiator solution dropwise. After the dropwise addition is complete, heat and stir to react for 2-3 hours. After the reaction is complete, add the reinforcing agent and stir evenly to obtain mixture two for later use. S3. Mixing and blending: Mix mixture one and mixture two, add all the remaining initiator, heat and stir until well mixed, keep warm for 20-30 minutes, then add pH adjuster and defoamer, mix well, filter, and the environmentally friendly water-based composite adhesive is obtained.

2. The method for preparing an environmentally friendly water-based composite adhesive for transfer paper according to claim 1, characterized in that, The emulsifier is octylphenol polyoxyethylene ether (OP-10) or sodium alkyl sulfonate.

3. The method for preparing an environmentally friendly water-based composite adhesive for transfer paper according to claim 1, characterized in that, The initiator is ammonium persulfate, sodium persulfate, or potassium persulfate.

4. The method for preparing an environmentally friendly water-based composite adhesive for transfer paper according to claim 1, characterized in that, The pH adjuster is sodium hydroxide or concentrated ammonia.

5. The method for preparing an environmentally friendly water-based composite adhesive for transfer paper according to claim 1, characterized in that, The defoamer is a mineral oil defoamer or a modified organosilicon defoamer.

6. A method for preparing an environmentally friendly water-based composite adhesive for transfer paper according to any one of claims 1 to 5, characterized in that, The reaction temperature for heating and stirring polymerization in S1 is controlled at 45-50℃; the reaction temperature for heating and stirring in S2 is controlled at 80-85℃; and the temperature for heating and stirring to mix in S3 is controlled at 70-80℃.

7. An environmentally friendly water-based composite adhesive for transfer paper, characterized in that, It is prepared by the method according to any one of claims 1 to 6.