High adhesion heat resistant water-based sealant coating emulsion, its preparation method and application

Abstract

The application belongs to the technical field of high molecular polymer and functional coating, and discloses a high-adhesion heat-seal-resistant water-based coating emulsion, a preparation method and application thereof. The high-adhesion heat-seal-resistant water-based coating emulsion is prepared by emulsion copolymerization of (meth) acrylate monomers, (meth) acrylic monomers, silicone monomers and a specific acrylate modified cyclodextrin compound crosslinking agent. The high-adhesion heat-seal-resistant water-based coating emulsion can be used for preparing a PE film heat-seal-resistant coating after being mixed with a metallocene, a polyethylene wax emulsion, a scratch-resistant agent and a flat powder filler, and the obtained coating has good adhesion, water resistance and heat-seal performance.

Description

Technical Field

[0001] This invention belongs to the field of polymer and functional coating technology, specifically relating to a high-adhesion, heat-resistant, water-sealing coating emulsion, its preparation method, and its application. Background Technology

[0002] With the development of single recyclable packaging material technology, PE material only has heat-sealing performance but cannot be used independently for heat sealing. That is, when heat sealing is used independently, the surface layer will be melted by the high temperature hot knife and gradually burned through. To solve this defect, a coating layer that can withstand temperatures above 160 degrees Celsius without melting must be applied to the PE surface to solve the problem of sticking to the knife and ensure that the heat-sealed surface is flat and beautiful.

[0003] Patent CN 117343374A discloses a PE film with a heat-resistant coating and its preparation method. The method involves reacting isocyanate-terminated polyurethane with epoxy functional groups in a crosslinking agent to extend and crosslink the chain. The carbon-carbon double bonds in the crosslinking agent are grafted onto the PE surface via free radical reaction under UV light and a photoinitiator, forming a coating with high crosslinking density and good adhesion to the PE film. The crosslinked coating exhibits "infusible and insoluble" properties, significantly improving its heat resistance. Simultaneously, modified inorganic sheet fillers with a high aspect ratio improve the thermal shrinkage performance of the composite film. The sheet fillers reduce the filler dosage, thus minimizing the impact on film transparency. Modification with a silane coupling agent allows for grafting to improve adhesion to the PE layer. Overall, a PE film with excellent heat resistance is obtained without affecting the film's recyclability, flexibility, or transparency. However, the preparation method for this heat-resistant coating is complex and costly. Summary of the Invention

[0004] In view of the shortcomings and deficiencies of the existing technology, the primary objective of this 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 application of the above-mentioned high-adhesion heat-resistant water-based coating emulsion in heat-resistant coatings for PE films.

[0007] The objective of this invention is achieved through the following technical solution:

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

[0009] (1) Dissolve (meth)acrylate isocyanate ethyl ester in an anhydrous solvent, then add cyclodextrin compound to dissolve or disperse evenly, heat to 50-80℃ and stir to react, spray dry after reaction to obtain acrylate modified cyclodextrin compound crosslinking agent;

[0010] (2) Add (meth)acrylate monomers, (meth)acrylate monomers, organosilicon monomers, acrylate-modified cyclodextrin compounds, crosslinking agents and emulsifiers to deionized water, stir and emulsify to obtain an emulsion; then heat to 60-90℃, add initiator solution dropwise to carry out polymerization reaction to obtain a high-adhesion heat-resistant water-sealing coating emulsion.

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

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

[0013] Further, the (meth)acrylate monomers mentioned in step (2) are methyl acrylate, ethyl acrylate, butyl acrylate, isooctyl acrylate, methyl methacrylate, ethyl methacrylate, and butyl methacrylate;

[0014] Furthermore, the organosilicon monomer mentioned in step (2) is γ-methacryloyloxypropyltrimethoxysilane (KH-570).

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

[0016] Further, the emulsifier mentioned in step (2) is sodium alkyl sulfonate, sodium alkylbenzene sulfonate, alkylphenol polyoxyethylene ether, or fatty alcohol polyoxyethylene ether; the amount of emulsifier added is 1% to 5% of the total mass of (meth)acrylate monomers, (meth)acrylate monomers, organosilicon monomers, and acrylate-modified cyclodextrin compound crosslinking agent.

[0017] Furthermore, the initiator mentioned 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 above method.

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

[0020] Furthermore, the application method is as follows: the high-adhesion heat-resistant water-based coating emulsion is mixed evenly with metallocene, polyethylene wax emulsion, anti-scratch agent and matting filler, and then coated on the surface of PE film and dried and cured to obtain a heat-resistant sealing coating.

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

[0022] The composition includes 90%–95% water-based coating emulsion, 0.05%–2.5% metallocene, 2%–3% polyethylene wax emulsion, 0.5%–2% anti-scratch agent, and 0%–8% matting filler.

[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 beneficial effects of the present invention are:

[0025] (1) The acrylic waterborne coating emulsion of the present invention uses 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 PE film.

[0026] (2) The acrylic waterborne coating emulsion of the present invention uses specific organosilicon monomers for copolymerization, which can further improve the heat resistance and water resistance of the coating. The introduction of alkoxy coupling groups can significantly improve the adhesion to PE film and the bonding force with polysiloxane anti-scratch agent, thereby improving the scratch resistance effect. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0028] Example 1

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

[0030] (1) Dissolve ethyl isocyanate in DMF solvent, then add hydroxyethyl-β-cyclodextrin (average molecular degree of substitution is 7) and dissolve evenly. The molar ratio of ethyl isocyanate to hydroxyethyl-β-cyclodextrin is 2:1. Heat to 70℃ and stir for 3h. After the reaction is completed, spray dry to obtain acrylate-modified cyclodextrin compound crosslinking agent.

[0031] (2) Butyl acrylate, methyl methacrylate, acrylic acid, KH-570, acrylate-modified cyclodextrin compound crosslinking agent and emulsifier sodium dodecylbenzenesulfonate were added to deionized water in a mass ratio of 70:30:50:10:20:5 and stirred to emulsify to obtain an emulsion; then the temperature was raised to 70°C and 0.2% of the total weight of monomer ammonium persulfate initiator solution was added dropwise to carry out the polymerization reaction for 4 hours to obtain an acrylic resin waterborne 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 includes the following preparation steps:

[0034] (1) Dissolve ethyl isocyanate in DMF solvent, then add β-cyclodextrin to dissolve and disperse evenly. The molar ratio of ethyl isocyanate to β-cyclodextrin is 4:1. Heat to 70℃ and stir for 3 hours. After the reaction is completed, spray dry to obtain acrylate-modified cyclodextrin compound crosslinking agent.

[0035] (2) Butyl acrylate, methyl methacrylate, acrylic acid, KH-570, acrylate-modified cyclodextrin compound crosslinking agent and emulsifier sodium dodecylbenzenesulfonate were added to deionized water in a mass ratio of 70:30:50:10:10:4 and stirred to emulsify to obtain an emulsion; then the temperature was raised to 70°C and 0.2% of the total weight of monomers of ammonium persulfate initiator solution was added dropwise to carry out the polymerization reaction for 4 hours to obtain an acrylic resin waterborne 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 includes the following preparation steps:

[0038] (1) Dissolve ethyl isocyanate in DMF solvent, then add hydroxypropyl-β-cyclodextrin (average molecular degree of substitution is 5.2) and dissolve evenly. The molar ratio of ethyl isocyanate to hydroxyethyl-β-cyclodextrin is 6:1. Heat to 70℃ and stir for 3h. After the reaction is completed, spray dry to obtain acrylate-modified cyclodextrin compound crosslinking agent.

[0039] (2) Butyl acrylate, methyl methacrylate, acrylic acid, KH-570, acrylate-modified cyclodextrin compound crosslinking agent and emulsifier sodium dodecylbenzenesulfonate were added to deionized water in a mass ratio of 70:30:50:5:5:4 and stirred to emulsify to obtain an emulsion; then the temperature was raised to 70°C and 0.2% of the total weight of monomer ammonium persulfate initiator solution was added dropwise to carry out the polymerization reaction for 4 hours to obtain an acrylic resin waterborne 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 includes the following preparation steps:

[0042] (1) Dissolve ethyl isocyanate in DMF solvent, then add β-cyclodextrin to dissolve and disperse evenly. The molar ratio of ethyl isocyanate to β-cyclodextrin is 4:1. Heat to 80℃ and stir for 2 hours. After the reaction is completed, spray dry to obtain acrylate-modified cyclodextrin compound crosslinking agent.

[0043] (2) Isooctyl acrylate, ethyl acrylate, methacrylic acid, KH-570, acrylate-modified cyclodextrin compound crosslinking agent and emulsifier sodium dodecylbenzenesulfonate were added to deionized water in a mass ratio of 70:30:50:10:10:4 and stirred to emulsify to obtain an emulsion; then the temperature was raised to 80°C and 0.2% of the total weight of monomer ammonium persulfate initiator solution was added dropwise to carry out the polymerization reaction for 3 hours to obtain an acrylic resin waterborne 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, does not include the addition of an acrylate-modified cyclodextrin crosslinking agent, and includes the following preparation steps:

[0046] Butyl acrylate, methyl methacrylate, acrylic acid, KH-570, and sodium dodecylbenzene sulfonate emulsifier were added to deionized water in a mass ratio of 70:30:50:10:5 and stirred to emulsify, thus obtaining an emulsion. Then, the temperature was raised to 70°C, and 0.2% of the total weight of the monomers in an ammonium persulfate initiator solution was added dropwise to carry out a polymerization reaction for 4 hours, resulting in an acrylic resin waterborne 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 instead of acrylate-modified cyclodextrin compound crosslinking agent, with the rest being the same.

[0049] Comparative Example 3

[0050] A method for preparing an aqueous coating emulsion, which, compared with Example 1, does not include the addition of organosilicon monomer KH-570, includes 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 crosslinking agent and emulsifier sodium dodecylbenzenesulfonate were added to deionized water in a mass ratio of 70:30:50:20:5 and stirred to emulsify to obtain an emulsion; then the temperature was raised to 70°C and 0.2% of the total weight of the monomers of ammonium persulfate initiator solution was added dropwise to carry out the polymerization reaction for 4 hours to obtain an acrylic resin waterborne coating emulsion with a solid content of 40%.

[0053] Example 5

[0054] The application of the aqueous coating emulsions obtained in Examples 1-4 and Comparative Examples 1-3 in the heat-resistant sealing coating of PE film is described in the following method: 91% of the high-adhesion heat-resistant sealing aqueous coating emulsion is mixed evenly with 0.5% zirconium monoxide catalyst, 2.5% polyethylene wax emulsion, 1% polysiloxane anti-scratch agent DC51 and 5% silica matting filler by weight percentage, and then coated onto the surface of PE film and dried and cured to obtain the heat-resistant sealing coating.

[0055] The adhesion (according to GB / T13217.7-2023), water resistance (adhesion tested after immersion in 48℃ warm water for 48h and drying at 80℃), and heat-sealing performance (heat-sealing temperature 160℃, pressure 0.2MPa, time 0.4s; surface smoothness and knife adhesion of the heat-sealing coating were observed) of the obtained heat-sealing coating are shown in Table 1 below.

[0056] Table 1

[0057] test sample Adhesion strength Water resistance Heat-sealed surface flatness Sticking to knife 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％ Uneven shrinkage Sticky knife Comparative Example 2 87％ 86％ smooth non-stick knife Comparative Example 3 94％ 89％ smooth non-stick knife

[0058] The results of Example 1 and Comparative Example 1 show that the acrylic waterborne coating emulsion of the present invention, crosslinked with a specific acrylate-modified cyclodextrin compound crosslinking agent, can significantly improve the coating adhesion, water resistance, and heat-sealing performance. The coating obtained in Comparative Example 2 using a conventional pentaerythritol triacrylate crosslinking agent exhibits good water resistance and heat-sealing performance, but poor adhesion. The results of Example 1 and Comparative Example 3 show that copolymerization with organosilicon monomers can further improve the coating adhesion and water resistance.

[0059] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within 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 preparation steps include the following: (1) Dissolve (meth)acrylate isocyanate in an anhydrous solvent, then add cyclodextrin compound to dissolve or disperse evenly, heat to 50~80℃ and stir to react, spray dry after reaction to obtain acrylate modified cyclodextrin compound crosslinking agent; (2) Add (meth)acrylate monomers, (meth)acrylate monomers, organosilicon monomers, acrylate-modified cyclodextrin compounds, crosslinking agents and emulsifiers to deionized water, stir and emulsify to obtain an emulsion; then heat to 60~90℃, add initiator solution dropwise to carry out polymerization reaction to obtain a high-adhesion heat-resistant water-sealing coating emulsion. The molar ratio of (meth)acrylate isocyanate to cyclodextrin compound added in step (1) is 2~6:1; The organosilicon monomer mentioned in step (2) is γ-methacryloyloxypropyltrimethoxysilane; The mass ratio of (meth)acrylate monomers, (meth)acrylate monomers, organosilicon monomers, and acrylate-modified cyclodextrin compound crosslinking agents added in step (2) is 1:(0.2~0.8):(0.05~0.2)(0.05~0.2).

2. The method for preparing a high-adhesion, heat-resistant, water-sealing coating emulsion according to claim 1, characterized in that, The cyclodextrin compound mentioned in step (1) is cyclodextrin, hydroxyethyl cyclodextrin, hydroxypropyl cyclodextrin, carboxymethyl cyclodextrin, or amino cyclodextrin; 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 (meth)acrylate monomers mentioned in step (2) are methyl acrylate, ethyl acrylate, butyl acrylate, isooctyl acrylate, methyl methacrylate, ethyl methacrylate, and butyl methacrylate.

4. The method for preparing a high-adhesion, heat-resistant, water-sealing coating emulsion according to claim 1, characterized in that, The emulsifiers mentioned in step (2) are sodium alkyl sulfonate, sodium alkylbenzene sulfonate, alkylphenol polyoxyethylene ether, and fatty alcohol polyoxyethylene ether; the amount of emulsifier added is 1% to 5% of the total mass of (meth)acrylate monomers, (meth)acrylate monomers, organosilicon monomers and acrylate-modified cyclodextrin compound crosslinking agents.

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

6. A high-adhesion, heat-resistant, water-sealing coating emulsion, characterized in that, It is prepared by the method described in any one of claims 1 to 5.

7. The application of the high-adhesion, heat-resistant, water-based coating emulsion of claim 6 in the heat-resistant coating of PE film, characterized in that, The application method is as follows: a high-adhesion heat-resistant water-based coating emulsion is mixed evenly with metallocene, polyethylene wax emulsion, anti-scratch agent and matting filler, and then coated on the surface of PE film and dried and cured to obtain a heat-resistant coating.

8. The application according to claim 7, characterized in that, The proportions of each raw material by weight percentage are as follows: The composition includes 91% water-based coating emulsion, 0.5% metallocene, 2.5% polyethylene wax emulsion, 1% anti-scratch agent, and 5% matting filler.