Acrylate barrier emulsion capable of reducing surface tension of paper-based material and preparation method thereof

Abstract

The invention relates to the technical field of acrylic emulsions, and discloses an acrylic barrier emulsion capable of reducing the surface tension of paper-based materials and a preparation method thereof. The emulsion comprises isooctyl acrylate, styrene, methyl methacrylate, unsaturated organic acid, hydroxyethyl methacrylate, tert-butyl vinyl carbonate, crosslinking monomers, auxiliary agents, reactive emulsifiers, initiators, and deionized water. The film formation of the emulsion is facilitated by reasonable compounding of rigid and flexible monomers. The bonding of carboxyl and hydroxyl functional groups with paper-based fibers and the addition of crosslinking monomers improve the binding force between the coating and the paper base. The reactive emulsifier is added to prevent the reactive emulsifier from being free, thereby improving the waterproof and oil-proof performance of the polymer. The auxiliary agent is added at the initial stage of the reaction to fill the gap of tert-butyl vinyl carbonate, and tert-butyl vinyl carbonate is added in the form of post-addition, so that the papillary structure formed by tert-butyl vinyl carbonate located at the base layer of the polymer film can exert its excellent waterproof and oil-proof barrier performance.

Description

Technical Field

[0001] The invention relates to the technical field of acrylic ester emulsions, and in particular to an acrylic ester barrier emulsion capable of reducing the surface tension of a paper-based material and a preparation method thereof. Background Art

[0002] The pace of life in today's society is getting faster and faster, and the demand for disposable paper containers in daily life is constantly increasing. At present, the surface of the paper carrier of paper containers generally adopts PE coating. Compared with ordinary paper, PE coated paper has barrier effects such as waterproof and oil-proof, and can be widely used in the field of fast-moving consumer paper packaging container products. However, PE coated paper products have the disadvantage of being difficult to recycle and recycle through pulping. Therefore, discarded PE coated paper products face the problem of subsequent treatment. At present, discarded PE coated paper is generally disposed of by landfill or incineration. However, soil landfill of PE coated paper is difficult to degrade naturally, causing environmental pollution and waste of paper resources. The thick smoke and irritating and harmful gases generated by the incineration of PE coated paper will pollute the atmosphere. Both of the above treatment methods will have an impact on the environment.

[0003] Currently, the alternative to plastic materials on the market is PLA polylactic acid. Although PLA coating is biodegradable, its disadvantage is that it is expensive, which puts manufacturers under great cost pressure, and the current technology has not yet been widely promoted in the field of paper coating. Although ordinary acrylic emulsions are reasonably priced and have mature production technology, they have mediocre barrier properties and cannot give paper-based materials a good barrier effect.

[0004] Therefore, the market is in urgent need of an acrylic emulsion that can replace PE coating and has good barrier effect. It can be coated on paper-based materials to make barrier paper, which can not only solve the problem of difficult recycling of PE coated paper, but also reduce the surface tension of paper-based materials and achieve good barrier effect, thereby enhancing the application value of paper.

[0005] It can be seen that the existing technology still needs to be improved and enhanced. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide an acrylic emulsion having the ability to reduce the surface tension of paper-based materials and a preparation method thereof, in order to impart low surface tension to paper and to impart excellent barrier properties to the surface of the paper.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] An acrylic emulsion capable of reducing the surface tension of a paper-based material comprises the following components, calculated by weight: 35-43 parts of isooctyl acrylate, 32-40 parts of styrene, 5-10 parts of methyl methacrylate, 2-5 parts of unsaturated organic acid, 1-3 parts of hydroxyethyl methacrylate, 4-9 parts of tert-butyl vinyl carbonate, 1.5-3.5 parts of a cross-linking monomer, 0.5-2.5 parts of an auxiliary agent, 1.5-3.0 parts of a reactive emulsifier, 0.5-1.2 parts of an initiator, and 95-110 parts of deionized water.

[0009] The acrylic ester emulsion capable of reducing the surface tension of paper-based materials, wherein the unsaturated organic acid is one or more of acrylic acid, methacrylic acid and maleic anhydride.

[0010] The acrylic emulsion capable of reducing the surface tension of paper-based materials comprises one or more versatate vinyl carbonates selected from the group consisting of VV-9, VV-10 and VV-11.

[0011] The acrylic emulsion capable of reducing the surface tension of paper-based materials, wherein the crosslinking monomer is a silane coupling agent compounded with a multifunctional crosslinking agent; the silane coupling agent is one or more of vinyl trimethoxysilane, vinyl triethoxysilane, γ-aminopropyl triethoxysilane, and vinyl tert-butyl triperoxide silane; and the multifunctional crosslinking agent is one or more of ethylene glycol dimethacrylate and trimethylolpropane trimethacrylate.

[0012] The acrylic emulsion capable of reducing the surface tension of paper-based materials comprises the silane coupling agent and the multifunctional cross-linking agent in a weight ratio of 1:(1-4).

[0013] The acrylic emulsion having the function of reducing the surface tension of paper-based materials, wherein the reactive emulsifier is an anionic emulsifier and a nonionic emulsifier of Aidico compounded in a weight ratio of 1: (1-3); the anionic emulsifier is one or more of SR-10, SR-20, and SR-30, and the nonionic emulsifier is one or more of ER-10, ER-20, and ER-30.

[0014] The acrylic emulsion capable of reducing the surface tension of paper-based materials, wherein the auxiliary agent is one or more of paraffin wax, beeswax and carnauba wax.

[0015] The acrylic emulsion capable of reducing the surface tension of paper-based materials, wherein the initiator is one or more of ammonium persulfate, potassium persulfate, sodium persulfate, and tert-butyl hydroperoxide.

[0016] The acrylic emulsion capable of reducing the surface tension of paper-based materials further comprises 0.1 to 0.3 parts by weight of a defoamer, wherein the defoamer is one or more of a polyether defoamer and an organosilicon defoamer.

[0017] A method for preparing an acrylic emulsion capable of reducing the surface tension of a paper-based material comprises the following steps:

[0018] Preparation of base liquid A: Add deionized water, reactive emulsifier and auxiliary agent into the polymerization kettle, and heat the kettle to a temperature of 70-90°C;

[0019] Preparation of pre-emulsion B: add deionized water, reactive emulsifier, isooctyl acrylate, styrene, methyl methacrylate, unsaturated organic acid, hydroxyethyl methacrylate, and crosslinking monomer into a pre-emulsion tank at room temperature and pressure, stir and mix to form a uniform pre-emulsion B, and set aside;

[0020] Preparation of raw material C of the preparatory liquid: tert-butyl ester, for later use;

[0021] Preparation of initiator solution D: Add initiator and deionized water into an initiator tank at room temperature and pressure to prepare a uniform initiator solution D;

[0022] When the temperature in the polymerization kettle reaches 70-90°C, add 3-7% of the weight of the pre-emulsion B and 8-12% of the weight of the initiator solution D into the kettle, react for 10-30 minutes, and then drip the remaining pre-emulsion B and initiator solution D into the polymerization kettle at a constant speed, and the titration time is controlled at 220-280 minutes;

[0023] When the remaining pre-emulsion B is added dropwise, when the remaining amount of the pre-emulsion B is 40-45%, the preliminary liquid raw material C is added thereto, and after dispersion and stirring for 10-20 minutes, the pre-emulsion B added with the preliminary liquid raw material C is continuously added dropwise to the polymerization kettle;

[0024] After the pre-emulsion liquid B with the pre-liquid raw material C added is added dropwise, the temperature is kept for 1 to 2 hours, and the temperature of the polymerization kettle is controlled at 70 to 90°C;

[0025] The polymerization kettle is cooled to 40-50° C., a defoamer and a bactericide are added into the polymerization kettle, and the mixture is stirred for 0.5-1 h. The mixture is extracted under negative pressure and the material is filtered to obtain an acrylic barrier emulsion capable of reducing the surface tension of the paper-based material.

[0026] Beneficial effects:

[0027] The present invention provides an acrylic emulsion capable of reducing the surface tension of a paper-based material and a preparation method thereof, which has the following advantages:

[0028] 1. Through the reasonable compounding of rigid and flexible monomers, the glass transition temperature of 25-30℃ is set to make the polymer fully film-forming and exert its performance. The acrylate emulsion water evaporates and dries to form a continuous film. The carboxyl and hydroxyl functional groups provided by the unsaturated organic acid and hydroxyethyl methacrylate can assist the acrylate emulsion to bond with the paper-based material fiber, firmly bond, improve the bonding force, make up for the looseness and easy leakage of the porous structure of the paper-based material surface, and at the same time add cross-linkable groups to the polymer.

[0029] 2. By introducing tert-butyl carbonate through post-addition, the steric effect of the three alkyl groups on the α-carbon atom forms a papillary structure on the surface of the polymer to achieve a low surface tension hydrophobic lotus leaf effect. The α-carbon atom is used as a peak to support the water / oil molecule interface. The low surface tension prevents water / oil molecules from penetrating into the base layer of the polymer, making the polymer extremely hydrophobic. In addition, the post-addition introduction method makes tert-butyl carbonate mainly distributed in the outer layer of the polymer, which can greatly play the hydrophobic lotus leaf effect of the additive, achieve excellent waterproof and oil-proof barrier properties, and can also reduce the amount of raw materials used and save preparation costs.

[0030] 3. Add cross-linking monomers to the acrylic barrier emulsion, and use a combination of conventional silane coupling agents and multifunctional cross-linking monomers. Thanks to the silane bond energy, the inorganic fibers in the paper-based material can be firmly riveted, thereby strengthening the adhesion of the emulsion to the paper after coating. The multifunctional cross-linking monomer promotes the high cross-linking density of the polymer to form a network structure, giving the paper-based material a dense base surface, so that the paper-based material has a low surface tension, making it difficult for water / oil molecules to spread and penetrate the paper-based material, thereby achieving a leak-proof barrier effect.

[0031] 4. The reactive emulsifier has both emulsifying ability and is used to evenly disperse the oil phase monomers; it also has ethylene reactive groups, so that the reactive emulsifier can be polymerized to the polymer chain during the reaction, avoiding the mobility brought by the free state of the emulsifier, so that it can be firmly grafted to the polymer chain to improve the water resistance and oil resistance of the polymer. In addition, the acrylic ester barrier emulsion also utilizes the particle surface of the emulsion prepared by the reactive surfactant, the side chain has large steric hindrance, strong hydrophobicity, and the surface tension of the polymer after film formation is low, so that the paper-based material has water and oil resistance barrier properties.

[0032] 5. In the preparation method, the additives are added at the initial stage of the reaction, which is different from the conventional simple mixing of adding additives later. The reactive emulsifier can help the additives to be evenly distributed in the base layer of the polymer film, especially to improve the interstitial position caused by the steric hindrance of the α-carbon atom of tert-butyl vinyl carbonate. The superposition effect of the additives further reduces the surface tension of the polymer and enhances the water / oil resistance of the paper-based material.

[0033] 6. The polymerization method uses hot water or steam as the heating medium, the polymerization is controllable, the operation is very convenient, and the processing cost is low. The acrylic ester barrier emulsion can be prepared by heating and stirring, the operation is very convenient, and the processing cost is low. The preparation method of the present invention is superior to the PE coating process, which not only saves materials, but also the acrylic ester barrier latex can be recycled and re-pulped, which conforms to the concept of sustainable development and can greatly save expenses on raw materials; and the raw materials and emulsion products are in line with the use standard of additives for food contact materials and products GB9685-2006, and the standard of food contact paper and paperboard materials and products GB4806.8-2016. DETAILED DESCRIPTION

[0034] The present invention provides an acrylic emulsion capable of reducing the surface tension of a paper-based material and a preparation method thereof. In order to make the purpose, technical scheme and effect of the present invention clearer and more specific, the present invention is further described in detail with reference to the following examples. It should be understood that the specific examples described herein are only used to explain the present invention and are not intended to limit the scope of protection of the present invention.

[0035] The invention provides an acrylic ester emulsion capable of reducing the surface tension of a paper-based material. The acrylic ester emulsion comprises the following components, calculated by weight: 35-43 parts of isooctyl acrylate, 32-40 parts of styrene, 5-10 parts of methyl methacrylate, 2-5 parts of unsaturated organic acid, 1-3 parts of hydroxyethyl methacrylate, 4-9 parts of tert-carbonate vinyl ester, 1.5-3.5 parts of cross-linking monomer, 0.5-2.5 parts of auxiliary agent, 1.5-3.0 parts of reactive emulsifier, 0.5-1.2 parts of initiator, 0.1-0.3 parts of defoamer and 95-110 parts of deionized water.

[0036] Isooctyl acrylate, styrene and methyl methacrylate are used as the main structural monomers. The glass transition temperature of the rigid and flexible monomers is set to 25-30°C by reasonable compounding, avoiding the problem of brittle film formed by high glass transition temperature and sticky film formed by low glass transition temperature. The polymer can be suitable for film-forming conditions of 50-60°C in paper machines, so that the paper-based material can fully perform its film-forming properties. At the same time, styrene and methyl methacrylate are two rigid monomers / hard monomers with good water and oil resistance. Isooctyl acrylate is a flexible monomer / soft monomer. As a long-chain ester, it has strong hydrophobicity and provides a low surface tension basis for the polymer structure. Furthermore, the above raw materials are widely used in the market and are more cost-effective than PLA polylactic acid.

[0037] Acrylic emulsion water evaporates and dries to form a continuous adhesive film. The carboxyl and hydroxyl functional groups provided by unsaturated organic acids and hydroxyethyl methacrylate can assist the acrylic emulsion in bonding with the paper-based material fibers, firmly bond, and improve the bonding strength, making up for the looseness and easy leakage of the porous structure of the paper-based material surface, while adding cross-linkable groups to the polymer. Specifically, the unsaturated organic acid is one or more of acrylic acid, methacrylic acid, and maleic anhydride. The above-mentioned acrylic barrier emulsion can be applied by spraying or roller coating, and the coating method is simple, avoiding the shortcomings of the complex coating construction of PE film, while saving energy.

[0038] Versatile vinyl carbonate is a multi-branched monobasic saturated carboxylic acid vinyl ester. The steric effect of the three alkyl groups on the α-carbon atom forms a papillary structure on the surface of the polymer to achieve a low surface tension hydrophobic lotus leaf effect. The α-carbon atom is used as a peak to support the water / oil molecule interface. The low surface tension prevents water / oil molecules from penetrating into the base of the polymer, making it extremely hydrophobic. The double bonds in the versatile vinyl carbonate molecule give it a certain degree of reactivity, and it can be copolymerized with monomers such as acrylates and styrene to modify the monomers.

[0039] Further, the chemical formula of tert-butyl carbonate is: Among them, R1, R2, and R3 are alkyl substituents, at least one of which is methyl, and the number of carbon atoms in the substituents is 9 / 10 / 11, corresponding to three different monomer raw materials (VV-9, VV-10, VV-11). The steric hindrance and shielding effect generated by the three alkyl substituents formed in the chemical formula of versatile vinyl carbonate make the copolymer emulsion have good water resistance, chemical resistance, weather resistance, etc.

[0040] In some embodiments, the crosslinking monomer is a silane coupling agent compounded with a multifunctional crosslinking agent in a weight ratio of 1: (1-4); the silane coupling agent is one or more of vinyl trimethoxysilane, vinyl triethoxysilane, γ-aminopropyl triethoxysilane, and vinyl triperoxy tert-butyl silane; the multifunctional crosslinking agent is one or more of ethylene glycol dimethacrylate and trimethylolpropane trimethacrylate. The above crosslinking monomer is added to the acrylic barrier emulsion, and a conventional silane coupling agent and a multifunctional crosslinking monomer are compounded. Thanks to the silane bond energy, the inorganic fiber in the paper-based material is firmly riveted, and the bonding force of the emulsion after coating is strengthened to adhere to the paper. The multifunctional crosslinking monomer promotes the high crosslinking density of the polymer to form a network structure, giving the paper-based material a dense base surface, so that the paper-based material has a low surface tension, making it difficult for water / oil molecules to spread and penetrate the paper-based material, thereby achieving a barrier effect of anti-leakage.

[0041] In some embodiments, the reactive emulsifier is an anionic emulsifier and a nonionic emulsifier of EDICO compounded in a weight ratio of 1: (1-3); the anionic emulsifier is one or more of SR-10, SR-20, and SR-30, and the nonionic emulsifier is one or more of ER-10, ER-20, and ER-30. The above-mentioned reactive emulsifier has both emulsification ability and is used to evenly disperse the oil phase monomer; it also has an ethylene reaction group, so that the reactive emulsifier can be polymerized to the polymer chain during the reaction, avoiding the mobility brought by the free state of the emulsifier, so that it can be firmly grafted into the polymer chain to improve the water resistance and oil resistance of the polymer. In addition, the acrylic ester barrier emulsion also utilizes the particle surface of the emulsion prepared by the reactive surfactant, the side chain has large steric hindrance, strong hydrophobicity, and the surface tension of the polymer after film formation is low, so that the paper-based material has water-resistant and oil-resistant barrier properties.

[0042] In some embodiments, the auxiliary agent is one or more of paraffin wax, beeswax, and carnauba wax. The main component of wax is alkane, which plays a role in isolating water and oil.

[0043] In some embodiments, the initiator is one or more of ammonium persulfate, potassium persulfate, sodium persulfate, and tert-butyl hydroperoxide.

[0044] In some embodiments, the defoaming agent is one or more of a polyether defoaming agent and a silicone defoaming agent.

[0045] The present invention also provides a method for preparing an acrylic emulsion capable of reducing the surface tension of a paper-based material, comprising the following steps:

[0046] (1) Preparation of base liquid A: Add 40-46 parts of deionized water, 0.8-1.8 parts of reactive emulsifier, and 0.2-2.5 parts of auxiliary agent to a polymerization kettle equipped with a stirrer, a condenser, and a constant flow pump feeding device, and heat the kettle to a temperature of 70-90°C. Adding auxiliary agents at the initial stage of the reaction is different from the simple mixing of conventional auxiliary agents added later. Reactive emulsifiers can help the auxiliary agents to be evenly distributed in the base layer of the polymer film, especially improving the interstitial position caused by the steric hindrance of the α-carbon atom of tert-butyl vinyl carbonate. The superposition effect of the auxiliary agents further reduces the surface tension of the polymer and improves the water / oil barrier performance of the paper-based material.

[0047] (2) Preparation of pre-emulsion B: 35-39 parts of deionized water, 0.7-1.2 parts of reactive emulsifier, 35-43 parts of isooctyl acrylate, 32-40 parts of styrene, 5-10 parts of methyl methacrylate, 2-5 parts of unsaturated organic acid, 1-3 parts of hydroxyethyl methacrylate and 1.5-3.5 parts of crosslinking monomer were added to a pre-emulsion tank equipped with a monomer metering tank and a stirrer at room temperature and pressure, and the mixture was stirred to form a uniform pre-emulsion B, and stirred for 10-50 minutes for standby use.

[0048] (3) Preparation of preliminary liquid raw material C: 4 to 9 parts of tert-butyl ester, set aside.

[0049] (4) Preparation of initiator solution D: Add 0.5-1.2 parts of initiator and 20-25 parts of deionized water into an initiator tank equipped with a stirrer and a constant flow dripping device at room temperature and pressure to prepare a uniform initiator solution D.

[0050] (5) When the temperature in the polymerization kettle reaches 70-90°C, 3-7% of the weight of pre-emulsion B and 8-12% of the weight of initiator solution D are added into the kettle. After reacting for 10-30 minutes, the remaining pre-emulsion B and initiator solution D are added dropwise into the polymerization kettle at a constant rate. The titration time is controlled at 220-280 minutes.

[0051] (6) When the remaining pre-emulsion B is added dropwise, when the remaining amount of the pre-emulsion B is 40-45%, the preliminary liquid raw material C is added thereto, and after dispersion and stirring for 10-20 minutes, the pre-emulsion B added with the preliminary liquid raw material C is continuously added dropwise to the polymerization kettle. The versatate raw material is introduced by the post-addition process, so that the versatate raw material is mainly distributed in the outer layer of the polymer, which can greatly exert the hydrophobic lotus leaf effect of the additive, achieve excellent waterproof and oil-proof barrier properties, and can also reduce the amount of raw materials used and save preparation costs.

[0052] (7) After the addition of the pre-emulsion liquid B with the preparatory liquid raw material C, the temperature is kept for 1 to 2 hours, and the temperature of the polymerization kettle is controlled at 70 to 90°C. The polymerization method uses hot water or steam as the heating medium, the polymerization is controllable, the operation is very convenient, and the processing cost is low. The acrylic ester barrier emulsion can be prepared by heating and stirring, the operation is very convenient, and the processing cost is low. The preparation method of the present invention is superior to the PE coating process, not only saving materials, but also the acrylic ester barrier latex can be recycled and re-pulped, which is in line with the concept of sustainable development and can greatly save expenses on raw materials.

[0053] (8) The polymerization kettle is cooled to 40-50°C, 0.1-0.3 parts of defoamer and 0.1-0.3 parts of bactericide are added to the polymerization kettle, and stirred for 0.5-1h; negative pressure extraction is performed for 3-5 hours under the condition of -0.07-0.09MPa to reduce the VOC content in the emulsion. The material is filtered out to obtain an acrylic barrier emulsion with the function of reducing the surface tension of the paper-based material.

[0054] In order to further illustrate the acrylic ester barrier emulsion with the function of reducing the surface tension of paper-based materials and the preparation method thereof provided by the present invention, the following examples are provided.

[0055] Example 1

[0056] The invention discloses an acrylic barrier emulsion capable of reducing the surface tension of a paper-based material. The acrylic barrier emulsion comprises the following components, calculated by weight: 37 parts of isooctyl acrylate, 35 parts of styrene, 6 parts of methyl methacrylate, 3 parts of unsaturated organic acid (acrylic acid), 2 parts of hydroxyethyl methacrylate, 7 parts of tert-butyl vinyl carbonate, 2.5 parts of a cross-linking monomer (vinyl trimethoxysilane compounded with ethylene glycol dimethacrylate in a weight ratio of 1:3.5), 1.2 parts of an auxiliary agent (beeswax), 2.3 parts of a reactive emulsifier (1.15 parts of SR-20 and 1.15 parts of ER-30), 1 part of an initiator (sodium persulfate), 0.1 parts of a defoamer (organic silicon defoamer), and 110 parts of deionized water.

[0057] The preparation method thereof comprises the following steps:

[0058] (1) Preparation of base liquid A: Add 42 parts of deionized water, 1.5 parts of reactive emulsifier and 1.2 parts of auxiliary agent into a polymerization kettle equipped with a stirrer, a condenser and a constant flow pump feeding device, and heat the kettle until the temperature reaches 83°C.

[0059] (2) Preparation of pre-emulsion B: 37 parts of deionized water, 0.8 parts of reactive emulsifier, 37 parts of isooctyl acrylate, 35 parts of styrene, 6 parts of methyl methacrylate, 3 parts of unsaturated organic acid, 2 parts of hydroxyethyl methacrylate and 2.5 parts of cross-linking monomer were added to a pre-emulsion tank equipped with a monomer metering tank and a stirrer at room temperature and pressure, and the mixture was stirred to form a uniform pre-emulsion B, and stirred for 30 minutes for use.

[0060] (3) Preparation of preliminary solution raw material C: 7 parts of tert-butyl ester, set aside.

[0061] (4) Preparation of initiator solution D: Add 1 part of initiator and 21 parts of deionized water into an initiator tank equipped with a stirrer and a constant flow dripping device at room temperature and pressure to prepare a uniform initiator solution D.

[0062] (5) When the temperature in the polymerization kettle reaches 83°C, 5% of the weight of pre-emulsion B and 9% of the weight of initiator solution D are added into the kettle. After 15 minutes of reaction, the remaining pre-emulsion B and initiator solution D are added dropwise into the polymerization kettle at a constant rate. The titration time is controlled at 260 minutes.

[0063] (6) When the remaining pre-emulsion B is added dropwise, when the remaining amount of pre-emulsion B is 42%, the preliminary liquid raw material C is added thereto. After dispersion and stirring for 17 minutes, the pre-emulsion B to which the preliminary liquid raw material C is added is continuously added dropwise to the polymerization kettle.

[0064] (7) After the addition of the pre-emulsion B to which the preliminary liquid raw material C was added was completed, the temperature was kept at 83° C. for 1.5 h.

[0065] (8) The polymerization kettle is cooled to 45° C., 0.1 parts of a defoamer and 0.1 parts of a fungicide are added to the polymerization kettle, and the mixture is stirred for 1 hour. Negative pressure extraction is performed at -0.07 MPa for 4 hours, and the material is filtered to obtain an acrylic barrier emulsion capable of reducing the surface tension of a paper-based material.

[0066] Example 2

[0067] The invention discloses an acrylic barrier emulsion capable of reducing the surface tension of a paper-based material. The acrylic barrier emulsion comprises the following components, calculated by weight: 35 parts of isooctyl acrylate, 43 parts of styrene, 5 parts of methyl methacrylate, 5 parts of unsaturated organic acid (methacrylic acid), 1 part of hydroxyethyl methacrylate, 4 parts of tert-butyl vinyl carbonate, 3.5 parts of a cross-linking monomer (γ-aminopropyl triethoxysilane compounded with ethylene glycol dimethacrylate in a weight ratio of 1:1), 0.5 parts of an auxiliary agent (paraffin), 1.5 parts of a reactive emulsifier (0.5 parts of SR-30 and 1 part of ER-10), 1.2 parts of an initiator ammonium persulfate, 0.2 parts of a defoamer (polyether defoamer), and 95 parts of deionized water.

[0068] The preparation method thereof comprises the following steps:

[0069] (1) Preparation of base liquid A: Add 40 parts of deionized water, 0.8 parts of reactive emulsifier and 0.5 parts of auxiliary agent into a polymerization kettle equipped with a stirrer, a condenser and a constant flow pump feeding device, and heat the kettle until the temperature reaches 75°C.

[0070] (2) Preparation of pre-emulsion B: 35 parts of deionized water, 0.7 parts of reactive emulsifier, 35 parts of isooctyl acrylate, 32 parts of styrene, 5 parts of methyl methacrylate, 2 parts of unsaturated organic acid, 1 part of hydroxyethyl methacrylate and 1.5 parts of cross-linking monomer were added to a pre-emulsion tank equipped with a monomer metering tank and a stirrer at room temperature and pressure, and the mixture was stirred to form a uniform pre-emulsion B, and stirred for 10 minutes for standby use.

[0071] (3) Preparation of preliminary solution raw material C: 4 parts of tert-butyl ester, set aside.

[0072] (4) Preparation of initiator solution D: 0.5 parts of initiator and 20 parts of deionized water were added to an initiator tank equipped with a stirrer and a constant flow dripping device at room temperature and pressure to prepare a uniform initiator solution D.

[0073] (5) When the temperature in the polymerization kettle reaches 75°C, 3% of the weight of pre-emulsion B and 8% of the weight of initiator solution D are added into the kettle. After 10 minutes of reaction, the remaining pre-emulsion B and initiator solution D are added dropwise into the polymerization kettle at a constant rate. The titration time is controlled at 220 minutes.

[0074] (6) When the remaining pre-emulsion B is added dropwise, when the remaining amount of the pre-emulsion B is 40%, the preliminary liquid raw material C is added thereto. After dispersion and stirring for 10 minutes, the pre-emulsion B with the preliminary liquid raw material C added thereto is continued to be added dropwise to the polymerization kettle.

[0075] (7) After the addition of the pre-emulsion B to which the preliminary liquid raw material C was added was completed, the temperature was kept at 75°C for 1 hour.

[0076] (8) The polymerization kettle is cooled to 40° C., 0.2 parts of a defoamer and 0.2 parts of a fungicide are added to the polymerization kettle, and the mixture is stirred for 0.5 h. Negative pressure extraction is performed at -0.09 MPa for 3.5 hours, and the material is filtered to obtain an acrylic barrier emulsion capable of reducing the surface tension of paper-based materials.

[0077] Example 3

[0078] The invention discloses an acrylic barrier emulsion capable of reducing the surface tension of a paper-based material. The acrylic barrier emulsion comprises the following components, calculated by weight: 43 parts of isooctyl acrylate, 32 parts of styrene, 10 parts of methyl methacrylate, 2 parts of an unsaturated organic acid (maleic anhydride), 3 parts of hydroxyethyl methacrylate, 9 parts of vinyl carbonate, 1.5 parts of a crosslinking monomer (vinyl triethoxysilane compounded with trimethylolpropane trimethacrylate in a weight ratio of 1:2), 2.5 parts of an auxiliary agent (carnauba wax), 3.0 parts of a reactive emulsifier (0.75 parts of SR-10 and 2.25 parts of ER-20), 0.5 parts of an initiator (tert-butyl hydroperoxide), 0.3 parts of a defoamer (polyether defoamer), and 110 parts of deionized water.

[0079] The preparation method thereof comprises the following steps:

[0080] (1) Preparation of base liquid A: Add 46 parts of deionized water, 1.8 parts of reactive emulsifier and 2.5 parts of auxiliary agent into a polymerization kettle equipped with a stirrer, a condenser and a constant flow pump feeding device, and heat the kettle until the temperature reaches 90°C.

[0081] (2) Preparation of pre-emulsion B: 39 parts of deionized water, 1.2 parts of reactive emulsifier, 43 parts of isooctyl acrylate, 40 parts of styrene, 10 parts of methyl methacrylate, 5 parts of unsaturated organic acid, 3 parts of hydroxyethyl methacrylate and 3.5 parts of cross-linking monomer were added to a pre-emulsion tank equipped with a monomer metering tank and a stirrer at room temperature and pressure, and the mixture was stirred to form a uniform pre-emulsion B, and stirred for 50 minutes for standby use.

[0082] (3) Preparation of preliminary solution raw material C: 9 parts of tert-butyl ester, set aside.

[0083] (4) Preparation of initiator solution D: 1.2 parts of initiator and 25 parts of deionized water were added to an initiator tank equipped with a stirrer and a constant flow dripping device at room temperature and pressure to prepare a uniform initiator solution D.

[0084] (5) When the temperature in the polymerization kettle reaches 90°C, 7% of the weight of pre-emulsion B and 12% of the weight of initiator solution D are added into the kettle. After reacting for 30 minutes, the remaining pre-emulsion B and initiator solution D are added dropwise into the polymerization kettle at a constant rate. The titration time is controlled at 280 minutes.

[0085] (6) When the remaining pre-emulsion B is added dropwise, when the remaining amount of the pre-emulsion B is 45%, the preliminary liquid raw material C is added thereto. After dispersion and stirring for 20 minutes, the pre-emulsion B with the preliminary liquid raw material C added thereto is continuously added dropwise to the polymerization kettle.

[0086] (7) After the addition of the pre-emulsified liquid B to which the preliminary liquid raw material C was added was completed, the temperature was kept at 90° C. for 2 hours.

[0087] (8) The polymerization kettle is cooled to 50° C., 0.3 parts of a defoaming agent and 0.3 parts of a fungicide are added to the polymerization kettle, and the mixture is stirred for 1 hour. Negative pressure extraction is performed at -0.08 MPa for 5 hours, and the material is filtered to obtain an acrylic barrier emulsion capable of reducing the surface tension of a paper-based material.

[0088] Comparative Example 1

[0089] An acrylic barrier emulsion capable of reducing the surface tension of a paper-based material comprises the following components, calculated by weight: 37 parts of isooctyl acrylate, 35 parts of styrene, 6 parts of methyl methacrylate, 3 parts of unsaturated organic acid (acrylic acid), 2 parts of hydroxyethyl methacrylate, 2.5 parts of a crosslinking monomer (vinyl trimethoxysilane compounded with ethylene glycol dimethacrylate in a weight ratio of 1:3.5), 1.2 parts of an auxiliary agent (beeswax), 2.3 parts of a reactive emulsifier (1.15 parts of SR-20 and 1.15 parts of ER-30), 1 part of an initiator (sodium persulfate), 0.1 parts of a defoamer (organic silicon defoamer), and 110 parts of deionized water.

[0090] Since no tert-butyl vinyl carbonate was added in Comparative Example 1, step (3) and step (6) were not present, and the remaining steps were the same as those in Example 1.

[0091] Comparative Example 2

[0092] The components and content of the acrylic ester barrier emulsion for reducing the surface tension of the paper-based material in Comparative Example 2 are the same as those in Example 1, except for the preparation method. In Comparative Example 2, versatate vinyl carbonate is added to the preparation of the pre-emulsion B in step (2).

[0093] Comparative Example 3

[0094] The components and contents of the acrylic barrier emulsion for reducing the surface tension of the paper-based material in Comparative Example 3 are the same as those in Example 1, except for the preparation method. In Comparative Example 3, the auxiliary agent in step (1) is added to step (6), that is, 1.2 parts of the auxiliary agent (beeswax) and 7 parts of versatate are added together to the remaining pre-emulsion B.

[0095] Comparative Example 4

[0096] The components and contents of the acrylic barrier emulsion for reducing the surface tension of paper-based materials in Comparative Example 4 are substantially the same as those in Example 1, except that the crosslinking monomer is composed of vinyl trimethoxysilane and ethylene glycol dimethacrylate in a weight ratio of 1:6.

[0097] Comparative Example 5

[0098] The latex purchased on the market is produced by Chuanhua Chemical Industry and its model is HS-1.

[0099] Comparative Example 6

[0100] PE coated paper products, the test product is a 7-ounce PE coated paper cup produced by Shenzhen Taimeile Paper Products Co., Ltd.

[0101] test

[0102] The latex prepared in Examples 1 to 3 and Comparative Examples 1 to 5 was applied on a plate having a specification of 80 g / m 2 A4 kraft paper and prepared to have a dry weight of 8 to 10 g / m 2 The test items and results of Examples 1 to 3 and Comparative Examples 1 to 6 are as follows:

[0103] 1. Test the performance of acrylic emulsions according to GB / T 20623-2006 "Emulsions for Architectural Coatings".

[0104] 2. Cobb value test: Use Cobb water absorption tester to measure the surface water absorption capacity of paper packaging samples. The test time is 30 minutes.

[0105] 3. Oil resistance test: The oil resistance grade determination method adopts TAPPI T 559cm-12 standard, which is: castor oil, toluene and n-heptane are used to prepare 12 test liquids (coded with numbers 1 to 12) in different proportions, and then these 12 different test liquids are used to determine the oil and grease resistance of paper packaging samples.

[0106] 4. Recycling performance test: The paper packaging samples were crushed by a hydraulic pulper for 5 minutes (4% pulp concentration, crushing speed 3000 rpm), and then passed through a 0.15 mm slit screen for hand sheet making. The paper recycling ratio (calculated as: paper fiber recovery rate = absolute dry weight of pulp after screening / absolute dry weight of pulp before screening × 100%) and the uniformity of the paper surface after recycling were evaluated.

[0107] 5. Coating surface tension test: Test in accordance with the testing standard GB / T 14216-2008 "Determination of wetting tension of plastic films and sheets".

[0108] Table 1 shows the emulsion performance test results of each sample

[0109]

[0110]

[0111] Table 2 shows the test results of barrier properties of each sample

[0112]

[0113]

[0114] Results Analysis

[0115] In Comparative Example 1, since no versatate was added, the polymer lacked a papillary structure, which increased the surface tension of the polymer and made it easier for water molecules / oil molecules to spread on the surface of the paper substrate, resulting in a decrease in the COBB value and the KIT equivalent.

[0116] The versatile vinyl carbonate in Comparative Example 2 is added together with other ingredients in the emulsion, that is, it is not added later. This process makes the versatile vinyl carbonate evenly distributed on the polymer chain. During the latex film extrusion process, the proportion of versatile vinyl carbonate in the outer layer is reduced and the papillary effect is reduced, thereby resulting in insufficient surface tension performance of the polymer and reduced water and oil barrier properties, which is not conducive to the barrier effect of versatile vinyl carbonate on the polymer.

[0117] In Comparative Example 3, the additives were added later, and the materials were simply mixed, resulting in insufficient and uneven dispersion, which led to a short-board barrier effect on the paper and reduced barrier performance.

[0118] In the crosslinking monomer of Comparative Example 4, the weight ratio of vinyl trimethoxysilane to ethylene glycol dimethacrylate is 1:6. The addition amount of ethylene glycol dimethacrylate is relatively large, which is not conducive to the riveting effect between silane and paper, causing the density of the improved paper to decline, resulting in a decrease in barrier properties.

[0119] The emulsion of Comparative Example 5 is applied to the surface of paper alone. Due to the large surface tension of the emulsion surface, water molecules / oil molecules easily spread on the surface of the emulsion. Moreover, the density of the emulsion is low, so the barrier effect cannot be achieved and it is easy to be penetrated. In addition, due to the defoaming agent additive (mineral oil) and the amount of residual VOC in Comparative Example 5, the commercially available latex does not meet the food grade GB9685-2006 and GB4806.8-2016.

[0120] From the above results, it can be seen that the barrier emulsions prepared in Examples 1 to 3 of the present invention have lower water absorption capacity, an oil resistance level of more than 10, and a lower coating surface tension. Compared with PE coated products, paper-based packaging products can be recycled and repulped, and meet the food grade GB9685-2006 and GB4806.8-2016.

[0121] It is understandable that those skilled in the art can make equivalent substitutions or changes based on the technical solution and inventive concept of the present invention, and all these changes or substitutions should fall within the protection scope of the present invention.

Claims

1. An acrylic barrier emulsion having the function of reducing the surface tension of a paper-based material, characterized in that: The composition comprises the following components by weight: 35-43 parts of isooctyl acrylate, 32-40 parts of styrene, 5-10 parts of methyl methacrylate, 2-5 parts of unsaturated organic acid and / or unsaturated organic acid anhydride, 1-3 parts of hydroxyethyl methacrylate, 4-9 parts of versatate vinyl carbonate, 1.5-3.5 parts of crosslinking monomer, 0.5-2.5 parts of auxiliary agent, 1.5-3.0 parts of reactive emulsifier, 0.5-1.2 parts of initiator, and 95-110 parts of deionized water; The unsaturated organic acid is one or both of acrylic acid and methacrylic acid; the unsaturated organic anhydride is maleic anhydride; the crosslinking monomer is a silane coupling agent compounded with a multifunctional crosslinking agent; the silane coupling agent is one or more of vinyl trimethoxysilane, vinyl triethoxysilane, γ-aminopropyl triethoxysilane, and vinyl triperoxy tert-butyl silane; the multifunctional crosslinking agent is one or more of ethylene glycol dimethacrylate and trimethylolpropane trimethacrylate; the weight ratio of the silane coupling agent to the multifunctional crosslinking agent is 1:(1-4); The method for preparing the acrylic barrier emulsion capable of reducing the surface tension of paper-based materials comprises the following steps: Preparation of base liquid A: Add deionized water, reactive emulsifier and auxiliary agent into the polymerization kettle, and heat the kettle to a temperature of 70-90°C; Preparation of pre-emulsion B: add deionized water, reactive emulsifier, isooctyl acrylate, styrene, methyl methacrylate, unsaturated organic acid and / or unsaturated organic anhydride, hydroxyethyl methacrylate, and crosslinking monomer into a pre-emulsion tank at room temperature and pressure, stir and mix to form a uniform pre-emulsion B, and set aside; Preparation of raw material C of the preparatory liquid: tert-butyl ester, for later use; Preparation of initiator solution D: Add initiator and deionized water into an initiator tank at room temperature and pressure to prepare a uniform initiator solution D; When the temperature in the polymerization kettle reaches 70-90°C, add 3-7% of the weight of the pre-emulsion B and 8-12% of the weight of the initiator solution D into the kettle, react for 10-30 minutes, and then drip the remaining pre-emulsion B and initiator solution D into the polymerization kettle at a constant speed, and the titration time is controlled at 220-280 minutes; When the remaining pre-emulsion B is added dropwise, when the remaining amount of the pre-emulsion B is 40-45%, the preliminary liquid raw material C is added thereto, and after dispersion and stirring for 10-20 minutes, the pre-emulsion B added with the preliminary liquid raw material C is continuously added dropwise to the polymerization kettle; After the pre-emulsion liquid B with the pre-liquid raw material C added is added dropwise, the temperature is kept for 1 to 2 hours, and the temperature of the polymerization kettle is controlled at 70 to 90°C; The polymerization kettle is cooled to 40-50° C., a defoamer and a bactericide are added into the polymerization kettle, and the mixture is stirred for 0.5-1 h. The mixture is extracted under negative pressure and the material is filtered to obtain an acrylic barrier emulsion capable of reducing the surface tension of the paper-based material.

2. The acrylic barrier emulsion having the function of reducing the surface tension of paper-based materials according to claim 1, characterized in that: The versatate vinyl carbonate is one or more of VV-9, VV-10 and VV-11.

3. The acrylic barrier emulsion having the function of reducing the surface tension of paper-based materials according to claim 1, characterized in that: The reactive emulsifier is an anionic emulsifier and a nonionic emulsifier of Aidico, compounded in a weight ratio of 1:(1-3); the anionic emulsifier is one or more of SR-10, SR-20, and SR-30, and the nonionic emulsifier is one or more of ER-10, ER-20, and ER-30.

4. The acrylic barrier emulsion having the function of reducing the surface tension of paper-based materials according to claim 1, characterized in that: The auxiliary agent is one or more of paraffin wax, beeswax and carnauba wax.

5. The acrylic barrier emulsion having the function of reducing the surface tension of paper-based materials according to claim 1, characterized in that: The initiator is one or more of ammonium persulfate, potassium persulfate, sodium persulfate, and tert-butyl hydroperoxide.

6. The acrylic barrier emulsion having the function of reducing the surface tension of paper-based materials according to claim 1, characterized in that: The invention also comprises 0.1 to 0.3 parts by weight of a defoamer, wherein the defoamer is one or more of a polyether defoamer and a silicone defoamer.

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