High-adhesion heat-resistant water-sealing coating emulsion as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of high-molecular polymers and functional coatings, and discloses a high-adhesion heat-resistant water-sealing coating emulsion as well as a preparation method and application thereof. The high-adhesion heat-resistant water-sealing coating emulsion is prepared from a (methyl) acrylate monomer, a (methyl) acrylic monomer, an organic silicon monomer and a specific acrylate modified cyclodextrin compound cross-linking agent through emulsion copolymerization. After being mixed with metallocene, a polyethylene wax emulsion, an anti-scraping agent and a matt powder filler, the epoxy resin can be used for preparing a heat-sealing-resistant coating of a PE film, and the obtained coating has good adhesive force, water resistance and heat sealing performance.

Description

Technical Field

[0001] The invention belongs to the technical field of high molecular polymers and functional coatings, and in particular relates to a high-adhesion heat-resistant water-sealing coating emulsion and a preparation method and application thereof. Background Art

[0002] With the development of single recyclable packaging technology, PE material only has heat sealing performance but cannot be used independently for heat sealing. That is, when used independently for heat sealing, the surface layer will be melted by the high-temperature hot knife first and gradually burned through. To solve this defect, a layer of coating that can withstand high temperatures above 160 degrees and will not be melted must be applied to the surface of PE to solve the problem of knife sticking and ensure that the heat-sealed surface is smooth and beautiful.

[0003] Patent CN 117343374A discloses a PE film with a heat-resistant coating and a preparation method thereof, wherein isocyanate-terminated polyurethane and epoxy functional groups in a cross-linking agent are reacted to extend the chain and cross-link, and the carbon-carbon double bonds in the cross-linking agent are grafted to the PE surface through free radical reaction under UV light and photoinitiator to form a coating with high cross-linking density and good bonding with the PE film, and the cross-linked coating has the characteristics of "infusible and insoluble", which can significantly improve its heat resistance. At the same time, a modified inorganic lamellar filler with a high aspect ratio is used to improve the heat shrinkage performance of the composite film, and the lamellar filler can reduce the amount of filler and thus reduce the impact on the transparency of the film. After modification with a silane coupling agent, the adhesion to the PE layer can be improved by grafting, and a PE film with excellent heat resistance is obtained as a whole, and the subsequent recyclability, softness and transparency of the PE film are not affected. However, the preparation method of the heat-resistant coating is relatively complicated and the cost is high. Summary of the invention

[0004] In view of the shortcomings and deficiencies of the above prior art, the primary purpose of the present invention is to provide a method for preparing a high-adhesion heat-resistant water-sealing coating emulsion.

[0005] Another object of the present invention is to provide a high-adhesion heat-resistant water-sealing coating emulsion prepared by the above method.

[0006] Another object of the present invention is to provide the use of the high-adhesion heat-seal resistant water-based coating emulsion in a PE film heat-seal resistant coating.

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

[0008] A method for preparing a high-adhesion heat-resistant water-sealing coating emulsion comprises the following preparation steps:

[0009] (1) dissolving isocyanoethyl (meth)acrylate in an anhydrous solvent, then adding a cyclodextrin compound to dissolve or disperse uniformly, heating to 50 to 80° C. and stirring to react, and spray drying after the reaction is completed to obtain an acrylate-modified cyclodextrin compound crosslinking agent;

[0010] (2) Adding (meth)acrylate monomers, (meth)acrylic acid monomers, silicone monomers, acrylate-modified cyclodextrin compound crosslinking agents and emulsifiers into deionized water, stirring and emulsifying to obtain an emulsion; then raising the temperature to 60-90° C., adding an initiator solution dropwise to carry out a polymerization reaction, and obtaining a high-adhesion, heat-resistant and water-sealing coating emulsion.

[0011] Furthermore, the cyclodextrin compound in step (1) is cyclodextrin (including α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin), hydroxyethyl cyclodextrin, hydroxypropyl cyclodextrin, carboxymethyl cyclodextrin, amino cyclodextrin; and the anhydrous solvent is DMF (N,N-dimethylformamide) or DMAC (N,N-dimethylacetamide).

[0012] Furthermore, in step (1), the molar ratio of isocyanoethyl (meth)acrylate to cyclodextrin compound is 2 to 6:1.

[0013] Furthermore, the (meth)acrylate monomer in step (2) is methyl acrylate, ethyl acrylate, butyl acrylate, isooctyl acrylate, methyl methacrylate, ethyl methacrylate, or butyl methacrylate;

[0014] Furthermore, the organic silicon monomer in step (2) is γ-methacryloxypropyltrimethoxysilane (KH-570).

[0015] Furthermore, in step (2), the mass ratio of the (meth)acrylate monomer, (meth)acrylic acid monomer, silicone monomer, and acrylate-modified cyclodextrin compound crosslinking agent added is 1:(0.2-0.8):(0.05-0.2)(0.05-0.2).

[0016] Furthermore, the emulsifier in step (2) is sodium alkyl sulfonate, sodium alkylbenzene sulfonate, alkylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether; the amount of the emulsifier added is 1% to 5% of the total mass of the (meth)acrylate monomer, (meth)acrylic acid monomer, silicone monomer and acrylate-modified cyclodextrin compound crosslinker.

[0017] Furthermore, the initiator in step (2) is ammonium persulfate, sodium persulfate or potassium persulfate.

[0018] A high-adhesion heat-resistant water-sealing coating emulsion is prepared by the method.

[0019] Application of the above-mentioned high-adhesion heat-seal resistant water-based coating emulsion in PE film heat-seal resistant coating.

[0020] Furthermore, the application method is: evenly mix the high-adhesion heat-resistant seal water-based coating emulsion with metallocene, polyethylene wax emulsion, anti-scratch agent and matte powder filler, and then apply it on the surface of the PE film to dry and solidify to obtain the heat-resistant seal coating.

[0021] Furthermore, in the above application method, the proportion of each raw material by weight percentage is as follows:

[0022] Water-based coating emulsion 90%-95%, metallocene 0.05%-2.5%, polyethylene wax emulsion 2%-3%, anti-scratch agent 0.5%-2%, matte powder filler 0-8%.

[0023] Furthermore, the anti-scratch agent is a polysiloxane anti-scratch agent, such as Dow Corning DC51 anti-scratch agent.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The acrylic acid water-based coating emulsion of the present invention adopts a specific acrylate-modified cyclodextrin compound crosslinking agent, which can significantly improve the coating strength, water resistance and heat resistance. At the same time, the introduced cyclodextrin compound crosslinking unit can provide a large number of polar groups, which can significantly improve the adhesion to the PE film.

[0026] (2) The acrylic water-based coating emulsion of the present invention adopts specific silicone monomers for copolymerization, which can further improve the heat resistance and water resistance of the coating, and the introduction of alkoxy coupling groups can significantly improve the adhesion to the PE film and the binding force with the polysiloxane anti-scratch agent, thereby improving the scratch resistance effect. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

[0028] Example 1

[0029] A method for preparing a high-adhesion heat-resistant water-sealing coating emulsion comprises the following preparation steps:

[0030] (1) Dissolve isocyanoethyl methacrylate in DMF solvent, then add hydroxyethyl-β-cyclodextrin (average molecular substitution degree is 7) and dissolve evenly, the molar ratio of isocyanoethyl methacrylate to hydroxyethyl-β-cyclodextrin is 2:1, heat to 70° C. and stir to react for 3 h. After the reaction is completed, spray dry to obtain an acrylate-modified cyclodextrin compound crosslinker.

[0031] (2) Butyl acrylate, methyl methacrylate, acrylic acid, KH-570, an acrylate-modified cyclodextrin compound crosslinker and an emulsifier, sodium dodecylbenzene sulfonate, are added to deionized water in a mass ratio of 70:30:50:10:20:5, stirred and emulsified to obtain an emulsion; then the temperature is raised to 70° C., and an ammonium persulfate initiator solution containing 0.2% of the total weight of the monomers is added dropwise to carry out a polymerization reaction for 4 hours to obtain an acrylic resin aqueous coating emulsion with a solid content of 40%.

[0032] Example 2

[0033] A method for preparing a high-adhesion heat-resistant water-sealing coating emulsion comprises the following preparation steps:

[0034] (1) Dissolve isocyanoethyl acrylate in DMF solvent, then add β-cyclodextrin to dissolve and disperse evenly, the molar ratio of isocyanoethyl methacrylate to β-cyclodextrin is 4:1, heat to 70° C. and stir to react for 3 h, spray dry after the reaction is completed, and obtain an acrylate-modified cyclodextrin compound crosslinker.

[0035] (2) Butyl acrylate, methyl methacrylate, acrylic acid, KH-570, an acrylate-modified cyclodextrin compound crosslinker and an emulsifier, sodium dodecylbenzene sulfonate, are added to deionized water in a mass ratio of 70:30:50:10:10:4, stirred and emulsified to obtain an emulsion; then the temperature is raised to 70° C., and an ammonium persulfate initiator solution containing 0.2% of the total weight of the monomers is added dropwise to carry out a polymerization reaction for 4 hours to obtain an acrylic resin aqueous coating emulsion with a solid content of 40%.

[0036] Example 3

[0037] A method for preparing a high-adhesion heat-resistant water-sealing coating emulsion comprises the following preparation steps:

[0038] (1) Dissolve isocyanoethyl methacrylate in DMF solvent, then add hydroxypropyl-β-cyclodextrin (average molecular substitution degree is 5.2) and dissolve evenly, the molar ratio of isocyanoethyl methacrylate to hydroxyethyl-β-cyclodextrin is 6:1, heat to 70°C and stir to react for 3 hours, spray dry after the reaction is completed, and obtain an acrylate modified cyclodextrin compound crosslinker.

[0039] (2) Butyl acrylate, methyl methacrylate, acrylic acid, KH-570, an acrylate-modified cyclodextrin compound crosslinker and an emulsifier, sodium dodecylbenzene sulfonate, are added to deionized water in a mass ratio of 70:30:50:5:5:4, and stirred for emulsification to obtain an emulsion; then the temperature is raised to 70° C., and an ammonium persulfate initiator solution containing 0.2% of the total weight of the monomers is added dropwise to carry out a polymerization reaction for 4 hours to obtain an acrylic resin aqueous coating emulsion with a solid content of 40%.

[0040] Example 4

[0041] A method for preparing a high-adhesion heat-resistant water-sealing coating emulsion comprises the following preparation steps:

[0042] (1) Dissolve isocyanoethyl acrylate in DMF solvent, then add β-cyclodextrin to dissolve and disperse evenly, the molar ratio of isocyanoethyl methacrylate to β-cyclodextrin is 4:1, heat to 80° C. and stir to react for 2 h. After the reaction is completed, spray dry to obtain an acrylate-modified cyclodextrin compound crosslinker.

[0043] (2) Isooctyl acrylate, ethyl acrylate, methacrylic acid, KH-570, an acrylate-modified cyclodextrin compound crosslinker and an emulsifier, sodium dodecylbenzene sulfonate, are added to deionized water in a mass ratio of 70:30:50:10:10:4, and stirred for emulsification to obtain an emulsion; then the temperature is raised to 80° C., and an ammonium persulfate initiator solution containing 0.2% of the total weight of the monomers is added dropwise to carry out polymerization reaction for 3 hours to obtain an acrylic resin aqueous coating emulsion with a solid content of 40%.

[0044] Comparative Example 1

[0045] A method for preparing an aqueous coating emulsion, compared with Example 1, without adding an acrylate-modified cyclodextrin compound crosslinking agent, comprises the following preparation steps:

[0046] Butyl acrylate, methyl methacrylate, acrylic acid, KH-570 and emulsifier sodium dodecylbenzene sulfonate are added to deionized water in a mass ratio of 70:30:50:10:5, stirred and emulsified to obtain an emulsion; then the temperature is raised to 70°C, and an ammonium persulfate initiator solution with a total monomer weight of 0.2% is added dropwise to carry out polymerization reaction for 4 hours to obtain an acrylic resin aqueous coating emulsion with a solid content of 40%.

[0047] Comparative Example 2

[0048] A method for preparing an aqueous coating emulsion, compared with Example 1, uses an equal amount of pentaerythritol triacrylate crosslinking agent to replace the acrylate modified cyclodextrin compound crosslinking agent, and the rest is the same.

[0049] Comparative Example 3

[0050] A method for preparing an aqueous coating emulsion, compared with Example 1, without adding the organosilicon monomer KH-570, comprises the following preparation steps:

[0051] Step (1) is the same as in Example 1.

[0052] (2) Butyl acrylate, methyl methacrylate, acrylic acid, acrylate-modified cyclodextrin compound crosslinker and emulsifier sodium dodecylbenzene sulfonate are added to deionized water in a mass ratio of 70:30:50:20:5, stirred and emulsified to obtain an emulsion; then the temperature is raised to 70° C., and an ammonium persulfate initiator solution with a total monomer weight of 0.2% is added dropwise to carry out polymerization reaction for 4 hours to obtain an acrylic resin aqueous coating emulsion with a solid content of 40%.

[0053] Example 5

[0054] The aqueous coating emulsions obtained in Examples 1 to 4 and Comparative Examples 1 to 3 are used in a heat-resistant seal coating of a PE film. The application method is as follows: 91% of the high-adhesion heat-resistant seal aqueous coating emulsion is uniformly mixed with 0.5% of a zirconocene catalyst, 2.5% of a polyethylene wax emulsion, 1% of a polysiloxane anti-scratch agent DC51 and 5% of a silica mat powder filler, by weight percentage, and then coated on the surface of the PE film and dried and cured to obtain a heat-resistant seal coating.

[0055] The adhesion fastness (according to GB / T13217.7-2023), water resistance (immersed in 48°C warm water for 48 hours, dried at 80°C and then tested for adhesion fastness), and heat sealing performance (heat sealing temperature 160°C, pressure 0.2 MPa, time 0.4s. Observe the surface flatness and knife sticking of the heat sealing coating) of the obtained heat seal resistant coating. The results are shown in Table 1 below.

[0056] Table 1

[0057] Test sample Adhesion fastness Water resistance Heat sealing surface flatness Knife sticking Example 1 100％ 97％ smooth Non-stick knife Example 2 98％ 95％ smooth Non-stick knife Example 3 97％ 92％ smooth Non-stick knife Example 4 97％ 95％ smooth Non-stick knife Comparative Example 1 93％ 82％ Shrinkage is uneven Sticky Knife Comparative Example 2 87％ 86％ smooth Non-stick knife Comparative Example 3 94％ 89％ smooth Non-stick knife

[0058] It can be seen from the results of Example 1 and Comparative Example 1 that the acrylic acid water-based coating emulsion of the present invention uses a specific acrylate-modified cyclodextrin compound crosslinking agent for crosslinking, which can significantly improve the adhesion, water resistance and heat sealing performance of the coating. The coating obtained by using conventional pentaerythritol triacrylate crosslinking agent in Comparative Example 2 has good water resistance and heat sealing performance, but poor adhesion performance. It can be seen from the results of Example 1 and Comparative Example 3 that the adhesion and water resistance of the coating can be further improved by copolymerization of silicone monomers.

[0059] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing a high-adhesion heat-resistant water-sealing coating emulsion, characterized in that: The method comprises the following preparation steps: (1) dissolving isocyanoethyl (meth)acrylate in an anhydrous solvent, then adding a cyclodextrin compound to dissolve or disperse uniformly, heating to 50 to 80° C. and stirring to react, and spray drying after the reaction is completed to obtain an acrylate-modified cyclodextrin compound crosslinking agent; (2) Adding (meth)acrylate monomers, (meth)acrylic acid monomers, silicone monomers, acrylate-modified cyclodextrin compound crosslinking agents and emulsifiers into deionized water, stirring and emulsifying to obtain an emulsion; then raising the temperature to 60-90° C., adding an initiator solution dropwise to carry out a polymerization reaction, and obtaining a high-adhesion, heat-resistant and water-sealing coating emulsion.

2. The method for preparing a high-adhesion heat-resistant water-sealing coating emulsion according to claim 1, characterized in that: The cyclodextrin compound in step (1) is cyclodextrin, hydroxyethyl cyclodextrin, hydroxypropyl cyclodextrin, carboxymethyl cyclodextrin, and amino cyclodextrin; and the anhydrous solvent is DMF or DMAC.

3. The method for preparing a high-adhesion heat-resistant water-sealing coating emulsion according to claim 1, characterized in that: The molar ratio of isocyanoethyl (meth)acrylate to cyclodextrin compound added in step (1) is 2 to 6:

1.

4. The method for preparing a high-adhesion heat-resistant water-sealing coating emulsion according to claim 1, characterized in that: The (meth)acrylate monomers in step (2) are methyl acrylate, ethyl acrylate, butyl acrylate, isooctyl acrylate, methyl methacrylate, ethyl methacrylate, and butyl methacrylate; and the silicone monomer is γ-methacryloxypropyltrimethoxysilane.

5. The method for preparing a high-adhesion heat-resistant water-sealing coating emulsion according to claim 1, characterized in that: The mass ratio of the (meth)acrylate monomer, (meth)acrylic acid monomer, silicone monomer, and acrylate-modified cyclodextrin compound crosslinking agent added in step (2) is 1:(0.2-0.8):(0.05-0.2)(0.05-0.2).

6. The method for preparing a high-adhesion heat-resistant water-sealing coating emulsion according to claim 1, characterized in that: The emulsifier in step (2) is sodium alkyl sulfonate, sodium alkylbenzene sulfonate, alkylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether; the amount of the emulsifier added is 1% to 5% of the total mass of the (meth)acrylate monomer, (meth)acrylic acid monomer, silicone monomer and acrylate modified cyclodextrin compound crosslinking agent.

7. The method for preparing a high-adhesion heat-resistant water-sealing coating emulsion according to claim 1, characterized in that: The initiator in step (2) is ammonium persulfate, sodium persulfate or potassium persulfate.

8. A high-adhesion heat-resistant water-sealing coating emulsion, characterized in that: It is prepared by the method according to any one of claims 1 to 7.

9. Application of a high-adhesion heat-seal resistant water-based coating emulsion as claimed in claim 8 in a PE film heat-seal resistant coating, characterized in that: The application method comprises the following steps: uniformly mixing the high-adhesion heat-resistant seal water-based coating emulsion with metallocene, polyethylene wax emulsion, anti-scratch agent and matte powder filler, and then coating the mixture on the surface of a PE film, drying and curing the mixture to obtain a heat-resistant seal coating.

10. The use according to claim 9, characterized in that: The proportions of each raw material by weight percentage are as follows: Water-based coating emulsion 90%-95%, metallocene 0.05%-2.5%, polyethylene wax emulsion 2%-3%, anti-scratch agent 0.5%-2%, matte powder filler 0-8%.