Water-based acrylate pressure-sensitive adhesive emulsion as well as preparation method and application thereof

Abstract

The invention discloses a water-based acrylate pressure-sensitive adhesive emulsion as well as a preparation method and application thereof, and the preparation method comprises the following steps: S1, providing an acrylate pre-emulsion A and an initiator solution B; s2, dropwise adding a part of the acrylate pre-emulsion A into the initiator solution B, and carrying out a heating reaction to obtain a polymer A emulsion; s3, providing a monomer composition B, and mixing the rest of the acrylate pre-emulsion A and the monomer composition B to obtain an acrylate pre-emulsion B; and S4, dropwise adding the acrylate pre-emulsion B into the polymer A emulsion, and heating for reaction to obtain the water-based acrylate pressure-sensitive adhesive emulsion. The water-based acrylate pressure-sensitive adhesive emulsion prepared by the preparation method disclosed by the invention has relatively good adhesiveness, mobility and PVC shrinkage resistance after being coated on a PVC base material.

Description

Technical Field

[0001] The present invention relates to the field of material technology, and more specifically, to an aqueous acrylate pressure-sensitive adhesive emulsion, a preparation method thereof, and an application thereof. Background Art

[0002] A pressure-sensitive adhesive (PSA) is an adhesive that can firmly adhere to an adherend after being lightly pressed, and is widely used in fields such as packaging, printing, medical treatment, household appliances, and manufacturing. Acrylate pressure-sensitive adhesives are a type of pressure-sensitive adhesive products obtained by copolymerizing various acrylate monomers. Since the acrylate polymers used to prepare acrylate pressure-sensitive adhesives do not have unsaturated bonds, acrylate pressure-sensitive adhesives have many unique advantages compared with other types of pressure-sensitive adhesives. For example, they have excellent antioxidant properties, are colorless, transparent, do not turn yellow, and have good anti-aging properties. Moreover, acrylate pressure-sensitive adhesives have good adhesion properties to various materials such as plastics, papers, metals, and ceramics. In addition, most acrylate pressure-sensitive adhesives are low-toxic and can be directly used in food packaging and medical and health products. Therefore, although acrylate pressure-sensitive adhesives were developed relatively late, they have developed rapidly and have strong vitality.

[0003] When an acrylate pressure-sensitive adhesive is coated on a PVC film, it can be made into PVC car stickers, labels, advertising films, etc. that can be used for decoration, advertising, and identification. At present, the pressure-sensitive adhesives used for PVC films are mainly solvent-based acrylate pressure-sensitive adhesives. However, with the requirements of environmental protection policies, solvent-based acrylate pressure-sensitive adhesives are gradually being replaced by aqueous acrylate pressure-sensitive adhesives. At the same time, with the progress of technology and the improvement of people's living standards, people's requirements for the performance of acrylate pressure-sensitive adhesives applied to PVC films are also getting higher and higher. Among them, in many fields, certain requirements are imposed on their adhesiveness, removability, and resistance to PVC shrinkage. However, traditional ordinary aqueous acrylate pressure-sensitive adhesives can no longer meet the requirements, and there are problems of poor resistance to PVC shrinkage and poor removability. Therefore, there is an urgent need for an aqueous acrylate pressure-sensitive adhesive emulsion with good adhesiveness, removability, and resistance to PVC shrinkage. Summary of the Invention

[0004] The purpose of the present invention is to solve the deficiencies of the prior art, and to provide an aqueous acrylate pressure-sensitive adhesive emulsion, a preparation method thereof, and an application thereof.

[0005] To achieve the above purpose, the technical solutions adopted by the present invention are as follows:

[0006] In the first aspect, the present invention provides a preparation method of an aqueous acrylate pressure-sensitive adhesive emulsion, including the following steps:

[0007] S1. Provide acrylate pre-emulsion A and initiator solution B;

[0008] S2. Drop part of acrylate pre-emulsion A into the initiator solution B and carry out a heating reaction to obtain polymer A emulsion;

[0009] S3. Provide monomer composition B, mix the remaining part of acrylate pre-emulsion A and the monomer composition B to obtain acrylate pre-emulsion B;

[0010] S4. Drop the acrylate pre-emulsion B into the polymer A emulsion and heat for reaction to obtain the aqueous acrylate pressure-sensitive adhesive emulsion;

[0011] Among them, the acrylate pre-emulsion A contains the following components: water, emulsifier, initiator A and monomer composition A; the initiator solution B contains the following components: water, buffer and initiator B.

[0012] In the present invention, the removability refers to the property that the glue (aqueous acrylate pressure-sensitive adhesive) can be easily removed without leaving residues without damaging the surface of the adherend after pasting.

[0013] Preferably, in step S1, the acrylate pre-emulsion A includes the following components in parts by weight:

[0014] Water 10 - 30 parts, emulsifier 1 - 5 parts, chain transfer agent 0 - 0.2 parts, initiator A 0.1 - 0.5 parts, monomer composition A 60 - 85 parts.

[0015] More preferably, the chain transfer agent is at least one of dodecyl mercaptan, isooctyl 3-mercaptopropionate, and α-methylstyrene dimer (AMSD).

[0016] Preferably, based on 100 parts by weight of the monomer composition A, it includes the following components in parts by weight:

[0017] Soft monomer 65 - 90 parts, hard monomer 2 - 20 parts, functional monomer A 2 - 15 parts; the soft monomer is at least one of butyl acrylate and isooctyl acrylate; the hard monomer is at least one of methyl methacrylate and styrene; the functional monomer A contains N-methylolacrylamide and monomer X, and the monomer X includes at least one of acrylic acid and 2-hydroxyethyl methacrylate.

[0018] Preferably, the emulsifier is at least one of sodium fatty alcohol polyoxyethylene ether sulfate, sodium alkyl sulfosuccinate, and sodium dioctyl sulfosuccinate.

[0019] Preferably, the initiator A is at least one of ammonium persulfate, potassium persulfate, and sodium persulfate.

[0020] Preferably, in the initiator solution B, the weight ratio of the water, buffer, and initiator B is 100:(0.1 - 0.3):(0.5 - 1.5).

[0021] Preferably, the weight ratio of the initiator A and initiator B is 1:(0.5 - 3).

[0022] Preferably, in the initiator solution B, the buffer is at least one of sodium bicarbonate, sodium carbonate, sodium acetate, and sodium bisulfite.

[0023] Preferably, in the initiator solution B, the initiator B is at least one of ammonium persulfate, potassium persulfate, and sodium persulfate.

[0024] Preferably, the initiator solution B is obtained by heating the water and buffer, and then adding the initiator B, and the heating temperature is 75 - 85°C.

[0025] Preferably, in step S2, the weight ratio of the partial acrylate pre-emulsion A to the acrylate pre-emulsion A is (0.7 - 0.9):1.

[0026] Preferably, in step S2, the weight ratio of the partial acrylate pre-emulsion A to the initiator solution B is 1:(0.2 - 1.5).

[0027] Preferably, in step S2, the temperature of the heating reaction is 75 - 85°C.

[0028] Preferably, in step S2, the dropping time of the partial acrylate pre-emulsion A is 2 - 5 h.

[0029] Preferably, in step S3, the weight ratio of the remaining part of the acrylate pre-emulsion A to the acrylate pre-emulsion A is (0.1 - 0.3):1.

[0030] Preferably, in step S3, the weight ratio of the remaining part of the acrylate pre-emulsion A to the monomer composition B is 1:(0.06 - 1.7).

[0031] Preferably, the weight ratio of the monomer composition A and the monomer composition B in the acrylate pre-emulsion A is 10:(0.1 - 2), such as 10:0.1, 10:0.2, 10:0.3, 10:0.4, 10:0.5, 10:0.6, 10:0.7, 10:0.8, 10:0.9, 10:1, 10:1.1, 10:1.2, 10:1.3, 10:1.4, 10:1.5, 10:1.6, 10:1.7, 10:1.8, 10:1.9, 10:2, and more preferably 10:(0.5 - 1.2).

[0032] The weight ratio of the monomer composition A to the monomer composition B in the acrylate pre-emulsion A should not exceed the above range. If it exceeds the above range, the adhesiveness, removability and PVC shrinkage resistance of the synthesized aqueous acrylate pressure-sensitive adhesive emulsion will deteriorate.

[0033] Preferably, in the remaining acrylate pre-emulsion A, the weight ratio of the monomer composition A to the monomer composition B is 10:(0.33 - 20), such as 10:0.33, 10:0.5, 10:1, 10:1.5, 10:2, 10:2.5, 10:3, 10:3.5, 10:4, 10:4.5, 10:5, 10:5.5, 10:6, 10:6.5, 10:7, 10:7.5, 10:8, 10:8.5, 10:9, 10:9.5, 10:10, 10:10.5, 10:11, 10:11.5, 10:12, 10:12.5, 10:13, 10:13.5, 10:14, 10:14.5, 10:15, 10:15.5, 10:16, 10:16.5, 10:17, 10:17.5, 10:18, 10:18.5, 10:19, 10:19.5, 10:20, and more preferably 10:(2 - 10).

[0034] Preferably, in step S3, based on 100 parts by weight of the monomer composition B, it includes the following components in parts by weight:

[0035] 30 - 80 parts of acrylate monomer and 20 - 70 parts of acrylic functional monomer;

[0036] Among them, the acrylate monomer is at least one of C1 - C8 alkyl acrylate and C1 - C8 alkyl methacrylate;

[0037] The acrylic functional monomer is an acrylate containing at least one functional group among carboxyl (-COOH), hydroxyl (-OH), acyl (R - CO-), amino (-NH2), and ureido (urea is CO(NH2)2).

[0038] More preferably, in step S3, based on 100 parts by weight of the monomer composition B, it includes the following components in parts by weight:

[0039] 50 - 80 parts of acrylate monomer and 20 - 50 parts of acrylic functional monomer.

[0040] More preferably, it includes at least one of the following (1) - (3):

[0041] (1) The C1 - C8 alkyl acrylate is at least one of methyl acrylate, ethyl acrylate, butyl acrylate, and isooctyl acrylate;

[0042] (2) The C1-C8 alkyl methacrylate is at least one of methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, and isooctyl methacrylate;

[0043] (3) The acrylic functional monomer is at least one of acrylic acid, acrylonitrile, methacrylic acid, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, acrylamide, β-acryloyloxypropionic acid, and ethoxylated methyleneurea methacrylate.

[0044] Preferably, the dropping time of the acrylate pre-emulsion B is 0.5 - 2 h.

[0045] Preferably, in step S4, the temperature of the reaction is 75 - 85 °C.

[0046] Preferably, in step S4, the reaction time is 1.5 - 3 h.

[0047] Preferably, after the reaction by heating in step S4, it further includes cooling, adjusting the pH, and adding an auxiliary agent.

[0048] More preferably, the cooling means cooling to a temperature ≤ 45 °C.

[0049] Even more preferably, the cooling means cooling to a temperature of 20 - 45 °C.

[0050] More preferably, the pH is adjusted to pH = 7 - 9.

[0051] More preferably, the pH adjuster for adjusting the pH is at least one of ammonia water, potassium hydroxide, sodium hydroxide, monoethanolamine, diethanolamine, and triethanolamine.

[0052] More preferably, the weight ratio of the acrylate pre-emulsion A to the auxiliary agent is 1:(0.004 - 0.02).

[0053] More preferably, the auxiliary agent is at least one of an antifoaming agent, a wetting agent, and a preservative.

[0054] Common antifoaming agents, wetting agents, and preservatives in the art can be used in the present invention.

[0055] Even more preferably, the weight ratio of the antifoaming agent, the wetting agent, and the preservative is (1 - 3):(1 - 5):(1 - 5).

[0056] Even more preferably, it includes at least one of the following:

[0057] (1) The antifoaming agent is at least one of silicone, mineral oil, and modified polysiloxane;

[0058] (2) The wetting agent is at least one of organic geminal alkyl alcohol ethers, polyether siloxanes, and alkynols;

[0059] (3) The preservative is at least one of formaldehyde, sodium nitrate, 5-chloro-2-methyl-4-isothiazolin-3-one (CIT), 2-methyl-4-isothiazolin-3-one (MIT), and zinc pyrithione;

[0060] In a second aspect, the present invention provides an aqueous acrylate pressure-sensitive adhesive emulsion, which is prepared by the preparation method described in the first aspect.

[0061] In a third aspect, the present invention provides an application of the aqueous acrylate pressure-sensitive adhesive emulsion in PVC.

[0062] In the present invention, the application of the aqueous acrylate pressure-sensitive adhesive emulsion in PVC means coating the aqueous acrylate pressure-sensitive adhesive emulsion on PVC materials (including PVC films).

[0063] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0064] The aqueous acrylic pressure-sensitive adhesive emulsion prepared by the method of the present invention has good adhesion, mobility and PVC shrinkage resistance after being coated on a PVC substrate. The same type of commercially available acrylic pressure-sensitive adhesive emulsion cannot have good adhesion, mobility and PVC shrinkage resistance. Generally, traditional aqueous acrylic pressure-sensitive adhesive emulsions use a seed polymerization method, and the adhesion of the emulsion is good, but the molecular cohesion is poor, resulting in poor PVC shrinkage resistance and mobility. If the aqueous acrylic pressure-sensitive adhesive emulsion obtained by polymerizing the monomer composition A is simply mixed with the aqueous acrylic pressure-sensitive adhesive emulsion obtained by polymerizing the monomer composition B, the improvement of adhesion, mobility and PVC shrinkage resistance is limited due to the compatibility problem of the polymers. The present invention adopts a specific segmented injection process and formulation composition, which is believed to produce polymers of different compositions in the front, middle and back stages of the reaction. The polymer A produced by the polymerization of monomer composition A in the front stage reaction mainly provides basic adhesion performance, the polymer B produced by the polymerization of monomer composition B in the back stage reaction can provide good cohesive performance, and the middle stage reaction can produce polymers A+B of different compositions obtained by copolymerization of monomer composition A and monomer composition B, which have low molecular chain regularity and high flexibility, and can further improve adhesion performance. Therefore, the segmented injection and formulation composition of the present invention can obtain a water-based acrylic pressure-sensitive adhesive latex mixed with different types of polymers, which has good adhesion, transferability and PVC shrinkage resistance. The invention uses a simple method to make the synthesized polymer have good molecular polarity, cohesion and PVC shrinkage resistance, solves the problem that the traditional water-based acrylic pressure-sensitive adhesive latex cannot have both adhesion and cohesion, and makes the water-based acrylic pressure-sensitive adhesive latex coated on a PVC substrate show good adhesion, transferability and PVC shrinkage resistance, laying a foundation for the application and high performance of acrylic pressure-sensitive adhesive latex in the field of PVC substrate products. DETAILED DESCRIPTION

[0065] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0066] The experimental methods in the following examples and comparative examples without specifying specific conditions are generally carried out according to conventional conditions in the art or according to conditions recommended by the manufacturer; the raw materials, reagents, etc. used, unless otherwise specified, are all raw materials and reagents that can be obtained from commercial channels such as conventional markets.

[0067] In each embodiment and comparative example of the present invention, the use of reagents is as follows:

[0068] Emulsifier, sodium polyoxyethylene fatty alcohol ether sulfate, NOVELUTION PA89N, Sasol;

[0069] Defoamer, mineral oil, DF691, Solvay;

[0070] Wetting agent, organic geminal alkyl alcohol ether, ST5040, Yitai Company.

[0071] Preservative, mixture of CIT, MIT and sodium nitrate RS model, Thor Special Chemicals (Shanghai) Co., Ltd.

[0072] Example 1

[0073] This example provides an aqueous acrylate pressure-sensitive adhesive emulsion, and its preparation method includes the following steps:

[0074] S1. First, stir 150 g of pure water, 10 g of emulsifier (sodium lauryl polyoxyethylene ether sulfate), and 0.7 g of chain transfer agent (dodecyl mercaptan) in acrylate pre-emulsion A until dissolved, then add monomer composition A (specifically, 15 g of acrylic acid, 20 g of hydroxyethyl methacrylate, 20 g of methyl methacrylate, 450 g of butyl acrylate, 22 g of styrene, and 3.5 g of N-methylol acrylamide) while stirring, fully emulsify, and then add 2 g of initiator A (ammonium persulfate) and stir evenly to obtain acrylate pre-emulsion A; add 250 g of pure water and 0.4 g of buffer (sodium bicarbonate) to the reaction kettle for mixing, then heat to 83 °C while stirring, and then add 2 g of initiator B (ammonium persulfate) to obtain initiator solution B;

[0075] S2. Slowly drop a part of acrylate pre-emulsion A into initiator solution B, carry out a heating reaction at 81 - 83 °C, and the dropping time is 3 h to obtain polymer A emulsion;

[0076] S3. Add monomer composition B (specifically, 20 g of isobutyl methacrylate, 20 g of methyl methacrylate, and 20 g of methacrylic acid) to the remaining part of acrylate pre-emulsion A for mixing, and fully stir and emulsify to obtain acrylate pre-emulsion B;

[0077] S4. At 81 - 83 °C, drop acrylate pre-emulsion B into polymer A emulsion. The dropping time of acrylate pre-emulsion B is 1 h. After dropping, continue to heat to maintain 81 - 83 °C and react for 2 h, then cool down to 45 °C, adjust the pH to 7.5 with 14 mol / L ammonia water, and add 1.5 g of defoaming agent (DF691), 4 g of wetting agent (ST5040), and 1.5 g of preservative ( RS), thus obtaining the aqueous acrylate pressure-sensitive adhesive emulsion;

[0078] Among them, in step S1, the acrylate pre-emulsion A includes the following components in parts by weight:

[0079] 21.64 parts of pure water, 1.44 parts of emulsifier (sodium lauryl polyoxyethylene ether sulfate), 0.1 part of chain transfer agent (dodecyl mercaptan), 0.29 part of initiator A (ammonium persulfate), 76.53 parts of monomer composition A; based on 100 parts by weight of the monomer composition A, it includes the following components in parts by weight: 2.83 parts of acrylic acid, 3.77 parts of hydroxyethyl methacrylate, 3.77 parts of methyl methacrylate, 84.82 parts of butyl acrylate, 0 part of isooctyl acrylate, 4.15 parts of styrene, 0.66 part of N - hydroxymethylacrylamide;

[0080] In step S1, in the initiator solution B, the weight ratio of water, buffer (sodium bicarbonate), and initiator B (ammonium persulfate) is 100:0.16:0.8; the weight ratio of initiator A and initiator B is 1:1;

[0081] In step S2, the weight ratio of the partial acrylate pre - emulsion A to the acrylate pre - emulsion A is 0.75:1; the dropping time of the partial acrylate pre - emulsion A is 3 h;

[0082] In step S3, the weight ratio of the remaining part of the acrylate pre - emulsion A to the acrylate pre - emulsion A is 0.25:1; the weight ratio of monomer composition A to monomer composition B in the acrylate pre - emulsion A is 10:1.13; the weight ratio of monomer composition A to monomer composition B in the remaining part of the acrylate pre - emulsion A is 10:4.52;

[0083] Based on 100 parts by weight of the monomer composition B, it includes the following components in parts by weight:

[0084] 66.67 parts of acrylate monomer, 33.33 parts of acrylic functional monomer;

[0085] Among them, the acrylate monomer is isobutyl methacrylate and methyl methacrylate with a weight ratio of 1:1; the acrylic functional monomer is methacrylic acid;

[0086] The weight ratio of the acrylate pre - emulsion A to the auxiliary agent is 1:0.01, and the auxiliary agent is a defoaming agent (DF691), a wetting agent (ST5040), and a preservative ( RS) with a weight ratio of 3:8:3.

[0087] Example 2

[0088] This example provides an aqueous acrylate pressure - sensitive adhesive emulsion, and its preparation method includes the following steps:

[0089] S1. First, 150g of pure water, 10g of emulsifier (sodium fatty alcohol polyoxyethylene ether sulfate), and 0.7g of chain transfer agent (dodecyl mercaptan) in the components of the acrylate pre-emulsion A are stirred until dissolved, and then the monomer composition A (specifically 20g of acrylic acid, 20g of hydroxyethyl methacrylate, 20g of methyl methacrylate, 300g of butyl acrylate, 150g of isooctyl acrylate, 22g of styrene and 3.5g of N-hydroxymethyl acrylamide) is added while stirring, fully emulsified, and then 2g of initiator A (ammonium persulfate) is added and stirred evenly to obtain an acrylate pre-emulsion A; 250g of pure water and 0.4g of a buffer (sodium bicarbonate) are added to the reactor for mixing, and then heated to 83°C while stirring, and then 2g of initiator B (ammonium persulfate) is added to obtain an initiator solution B;

[0090] S2. uniformly dropping part of the acrylate pre-emulsion A into the initiator solution B, heating the reaction at 81-83 ° C for 3 hours to obtain a polymer A emulsion;

[0091] S3. The monomer composition B (specifically 15 g of isooctyl methacrylate, 15 g of acrylamide and 20 g of methyl methacrylate) was added to the remaining portion of the acrylate pre-emulsion A and mixed, and stirred and emulsified to obtain an acrylate pre-emulsion B;

[0092] S4. At 81-83°C, add acrylate pre-emulsion B to polymer A emulsion dropwise for 1 hour. After the addition, continue heating to maintain 81-83°C and react for 2 hours. Then cool to 45°C, adjust pH to 7.5 with 14 mol / L ammonia water, add 1.5 g defoamer (DF691), 4 g wetting agent (ST5040) and 1.5 g preservative ( RS), to obtain an aqueous acrylate pressure-sensitive adhesive latex;

[0093] Wherein, in step S1, the acrylate pre-emulsion A comprises the following components in parts by weight:

[0094] 21.48 parts of pure water, 1.43 parts of emulsifier (sodium fatty alcohol polyoxyethylene ether sulfate), 0.1 parts of chain transfer agent (dodecyl mercaptan), 0.29 parts of initiator A (ammonium persulfate), 76.7 parts of monomer composition A; the monomer composition A, based on 100 parts by weight, includes the following components in parts by weight: 3.73 parts of acrylic acid, 3.73 parts of hydroxyethyl methacrylate, 3.73 parts of methyl methacrylate, 56.02 parts of butyl acrylate, 28.02 parts of isooctyl acrylate, 4.11 parts of styrene, and 0.66 parts of N-hydroxymethyl acrylamide;

[0095] In step S1, in the initiator solution B, the weight ratio of water, buffer (sodium bicarbonate), and initiator B (ammonium persulfate) is 100:0.16:0.8; the weight ratio of initiator A and initiator B is 1:1;

[0096] In step S2, the weight ratio of the partial acrylate pre-emulsion A to the acrylate pre-emulsion A is 0.75:1; the dropping time of the partial acrylate pre-emulsion A is 3 h;

[0097] In step S3, the weight ratio of the remaining acrylate pre-emulsion A to the acrylate pre-emulsion A is 0.25:1; the weight ratio of monomer composition A to monomer composition B in the acrylate pre-emulsion A is 10:0.93; the weight ratio of monomer composition A to monomer composition B in the remaining acrylate pre-emulsion A is 10:3.72;

[0098] Based on 100 parts by weight of the monomer composition B, it includes the following components in parts by weight:

[0099] 70 parts of acrylate monomer and 30 parts of acrylic functional monomer;

[0100] Among them, the acrylate monomer is isooctyl methacrylate and methyl methacrylate with a weight ratio of 3:4; the acrylic functional monomer is acrylamide;

[0101] The weight ratio of the acrylate pre-emulsion A to the auxiliary agent is 1:0.01, and the auxiliary agent is a defoaming agent (DF691), a wetting agent (ST5040), and a preservative ( RS) with a weight ratio of 3:8:3.

[0102] Example 3

[0103] This example provides an aqueous acrylate pressure-sensitive adhesive emulsion, and its preparation method includes the following steps:

[0104] S1. First, stir 150 g of pure water, 10 g of emulsifier (sodium fatty alcohol polyoxyethylene ether sulfate), and 0.7 g of chain transfer agent (dodecyl mercaptan) in the acrylate pre-emulsion A until dissolved, then add monomer composition A (specifically, 15 g of acrylic acid, 20 g of hydroxyethyl methacrylate, 15 g of methyl methacrylate, 150 g of butyl acrylate, 300 g of isooctyl acrylate, 22 g of styrene, and 3.5 g of N-methylol acrylamide) while stirring, fully emulsify, and then add 2.5 g of initiator A (ammonium persulfate) and stir evenly to obtain the acrylate pre-emulsion A; add 250 g of pure water and 0.4 g of buffer (sodium bicarbonate) to the reaction kettle for mixing, then heat to 83 °C while stirring, and then add 2.5 g of initiator B (ammonium persulfate) to obtain the initiator solution B;

[0105] S2. Slowly drop a part of acrylate pre-emulsion A into initiator solution B, carry out a heating reaction at 81 - 83 °C for 3 h to obtain polymer A emulsion;

[0106] S3. Add monomer composition B (specifically 20 g of methyl methacrylate and 20 g of β-acryloyloxypropionic acid) to the remaining part of acrylate pre-emulsion A for mixing, and fully stir and emulsify to obtain acrylate pre-emulsion B;

[0107] S4. At 81 - 83 °C, drop acrylate pre-emulsion B into polymer A emulsion. The dropping time of acrylate pre-emulsion B is 1 h. After dropping, continue heating to maintain 81 - 83 °C and react for 2 h, then cool down to 45 °C, adjust the pH to 7.5 with 14 mol / L ammonia water, and add 1.5 g of defoamer (DF691), 4 g of wetting agent (ST5040) and 1.5 g of preservative ( RS) to obtain the aqueous acrylate pressure-sensitive adhesive emulsion;

[0108] Among them, in step S1, the acrylate pre-emulsion A includes the following components in parts by weight:

[0109] 21.78 parts of pure water, 1.45 parts of emulsifier (sodium lauryl polyoxyethylene ether sulfate), 0.1 part of chain transfer agent (dodecyl mercaptan), 0.36 part of initiator A (ammonium persulfate), 76.31 parts of monomer composition A; The monomer composition A is calculated based on 100 parts by weight and includes the following components in parts by weight: 2.85 parts of acrylic acid, 3.81 parts of hydroxyethyl methacrylate, 2.85 parts of methyl methacrylate, 28.54 parts of butyl acrylate, 57.09 parts of isooctyl acrylate, 4.19 parts of styrene, 0.67 part of N-methylol acrylamide;

[0110] In step S1, the weight ratio of water, buffer (sodium bicarbonate), and initiator B (ammonium persulfate) is 100:0.16:1; The weight ratio of initiator A and initiator B is 1:1;

[0111] In step S2, the weight ratio of the part of acrylate pre-emulsion A to acrylate pre-emulsion A is 0.75:1; The dropping time of the part of acrylate pre-emulsion A is 3 h;

[0112] In step S3, the weight ratio of the remaining part of acrylate pre-emulsion A to acrylate pre-emulsion A is 0.25:1; The weight ratio of monomer composition A in acrylate pre-emulsion A to monomer composition B is 10:0.76; The weight ratio of monomer composition A in the remaining part of acrylate pre-emulsion A to monomer composition B is 10:3.04.

[0113] The monomer composition B, based on 100 parts by weight, comprises the following components in parts by weight:

[0114] 50 parts of acrylate monomer and 50 parts of acrylic acid functional monomer;

[0115] Among them, the acrylate monomer is methyl methacrylate; the acrylic acid functional monomer is β-acryloyloxypropionic acid;

[0116] The weight ratio of the acrylate pre-emulsion A to the auxiliary agent is 1:0.01. The auxiliary agent is a defoaming agent (DF691), a wetting agent (ST5040), and a preservative ( RS) with a weight ratio of 3:8:3.

[0117] Comparative Example 1

[0118] This comparative example provides an aqueous acrylate pressure-sensitive adhesive emulsion. The difference in its preparation method from that of Example 1 is that the monomer composition A lacks the functional monomer N-methylolacrylamide, and the monomer composition B lacks the functional monomer methacrylic acid, and they are equally replaced with methyl methacrylate. That is, the compositions of the monomer composition A and the monomer composition B in steps S1 and S3 are different from those in Example 1, specifically as follows:

[0119] S1. First, stir 150 g of pure water, 10 g of emulsifier (sodium lauryl polyoxyethylene ether sulfate), and 0.7 g of chain transfer agent (dodecyl mercaptan) in the acrylate pre-emulsion A until dissolved. Then, while stirring, add the monomer composition A (specifically, 15 g of acrylic acid, 20 g of hydroxyethyl methacrylate, 23.5 g of methyl methacrylate, 450 g of butyl acrylate, and 22 g of styrene), fully emulsify, and then add 2 g of initiator A (ammonium persulfate) and stir evenly to obtain the acrylate pre-emulsion A; add 250 g of pure water and 0.4 g of buffer (sodium bicarbonate) to the reaction kettle for mixing, then while stirring, heat to 83 °C, and then add 2 g of initiator B (ammonium persulfate) to obtain the initiator solution B;

[0120] S2. The same as in Example 1;

[0121] S3. Add the monomer composition B (specifically, 20 g of isobutyl methacrylate and 40 g of methyl methacrylate) to the remaining part of the acrylate pre-emulsion A for mixing, and fully stir and emulsify to obtain the acrylate pre-emulsion B;

[0122] S4. The same as in Example 1;

[0123] The rest refers to Example 1.

[0124] Comparative Example 2

[0125] This comparative example provides an aqueous acrylic pressure-sensitive adhesive emulsion, and the preparation method thereof is different from that of Example 2 only in that the weight ratio of the monomer composition A to the monomer composition B in the acrylic pre-emulsion A is 10:2.43, that is, the amount of the monomer composition B added in step S3 is different, as follows:

[0126] S1. The same as Example 2;

[0127] S2. The same as in Example 2;

[0128] S3. The monomer composition B (specifically 39 g of isooctyl methacrylate, 39 g of acrylamide and 52 g of methyl methacrylate) was added to the remaining portion of the acrylate pre-emulsion A and mixed, and stirred and emulsified to obtain an acrylate pre-emulsion B;

[0129] S4. The same as in Example 2;

[0130] The weight ratio of the monomer composition A to the monomer composition B is 10:2.43;

[0131] The rest are all referred to Example 2.

[0132] Comparative Example 3

[0133] This comparative example provides a water-based acrylic pressure-sensitive adhesive latex, and the preparation method thereof differs from that of Example 3 only in that no segmented injection is performed, that is, in step S1, the monomer composition B is merged into the monomer composition A, and the original step S3 of Example 3 is cancelled, and the details are as follows:

[0134] S1. First, 150g of pure water, 10g of emulsifier (sodium fatty alcohol polyoxyethylene ether sulfate), and 0.7g of chain transfer agent (dodecyl mercaptan) in the components of the acrylate pre-emulsion A are stirred until dissolved, and then monomer composition A (specifically 15g of acrylic acid, 20g of hydroxyethyl methacrylate, 15g of methyl methacrylate, 150g of butyl acrylate, 300g of isooctyl acrylate, 22g of styrene and 3.5g of N-hydroxymethyl acrylamide) and monomer composition B (specifically 20g of methyl methacrylate and 20g of β-acryloxypropionic acid) are added while stirring, fully emulsified, and then 2.5g of initiator A (ammonium persulfate) is added and stirred evenly to obtain an acrylate pre-emulsion; 250g of pure water and 0.4g of a buffer (sodium bicarbonate) are added to the reactor for mixing, and then heated to 83°C while stirring, and 2.5g of initiator B (ammonium persulfate) is first added to obtain an initiator solution B;

[0135] S2. uniformly dropping the acrylate pre-emulsion into the initiator solution B, heating the reaction at 81-83 ° C, and the dropping time of the acrylate pre-emulsion is 4h;

[0136] S3. After the dropping is completed, continue heating to maintain at 81 - 83 °C and react for 2 h. Then cool down to 45 °C, adjust the pH to 7.5 with 14 mol / L ammonia water, and add 1.5 g of defoamer (DF691), 4 g of wetting agent (ST5040) and 1.5 g of preservative ( RS) to obtain the aqueous acrylate pressure - sensitive adhesive emulsion;

[0137] The rest all refer to Example 3.

[0138] Comparative Example 4

[0139] This comparative example provides an aqueous acrylate pressure - sensitive adhesive emulsion. The difference in its preparation method from that of Example 1 is that first, part of the acrylate pre - emulsion A is added to the bottom of the reaction kettle, the temperature is raised and the initiator solution B is dropped to react to form a seed emulsion, then the monomer composition B and the initiator A are added to the remaining part of the acrylate pre - emulsion A, stirred and emulsified to obtain acrylate pre - emulsion B, and then the drop - wise polymerization reaction is carried out. The specific steps are as follows:

[0140] S1. First, stir 150 g of pure water, 10 g of emulsifier (sodium lauryl polyoxyethylene ether sulfate), and 0.7 g of chain transfer agent (dodecyl mercaptan) in the acrylate pre - emulsion A until dissolved, and then add the monomer composition A (specifically 15 g of acrylic acid, 20 g of hydroxyethyl methacrylate, 20 g of methyl methacrylate, 450 g of butyl acrylate, 22 g of styrene and 3.5 g of N - hydroxymethyl acrylamide) while stirring, and fully emulsify to obtain acrylate pre - emulsion A; mix 2 g of initiator B (ammonium persulfate) and 20 g of pure water to obtain the initiator solution B;

[0141] S2. Add 230 g of pure water and 0.4 g of buffer (sodium bicarbonate) to the reaction kettle for mixing, then add 10% of the acrylate pre - emulsion A, heat to 81 - 83 °C while stirring, and then add the initiator solution B to react for 0.5 h to obtain the seed emulsion;

[0142] S3. Add the monomer composition B (specifically 20 g of isobutyl methacrylate, 20 g of methyl methacrylate and 20 g of methacrylic acid) and 2 g of initiator A (ammonium persulfate) to the remaining part of the acrylate pre - emulsion A, stir and emulsify fully to obtain acrylate pre - emulsion B;

[0143] S4. At 81 - 83 °C, drop - wise add acrylate pre - emulsion B to the seed emulsion, the dropping time is 4 h. After the dropping is completed, continue heating to maintain at 81 - 83 °C and react for 2 h. Then cool down to 45 °C, adjust the pH to 7.5 with 14 mol / L ammonia water, and add 1.5 g of defoamer (DF691), 4 g of wetting agent (ST5040) and 1.5 g of preservative ( RS) to obtain the aqueous acrylate pressure - sensitive adhesive emulsion;

[0144] The rest refers to Example 1 for all.

[0145] Comparative Example 5

[0146] This comparative example provides an aqueous acrylate pressure-sensitive adhesive emulsion. The difference in its preparation method from that of Example 2 is only that the weight ratio of monomer composition A to monomer composition B in the acrylate pre-emulsion A is 10:0.075, that is, the addition amount of monomer composition B in step S3 is different, specifically as follows:

[0147] S1. The same as in Example 2;

[0148] S2. The same as in Example 2;

[0149] S3. Add monomer composition B (specifically 1.2 g of isooctyl methacrylate, 1.2 g of acrylamide, and 1.6 g of methyl methacrylate) to the remaining acrylate pre-emulsion A for mixing, and stir and emulsify fully to obtain acrylate pre-emulsion B;

[0150] S4. The same as in Example 2;

[0151] The weight ratio of monomer composition A to monomer composition B is 10:0.075;

[0152] The rest refers to Example 2 for all.

[0153] Performance Test

[0154] Perform performance tests on the aqueous acrylate pressure-sensitive adhesive emulsions of each example and comparative example, specifically as follows:

[0155] 1. Preparation of test samples:

[0156] Use pure water and a thickener (UH-420, Adeka) to adjust the solid content of the aqueous acrylate pressure-sensitive adhesive emulsion of each example or comparative example or commercial products 1-2 to 50% and the viscosity to 1000 cps, then coat it on a release paper of 25 cm × 40 cm, put it in an oven at 100 °C and dry for 5 min to make the dry adhesive thickness 18 - 22 μm, then transfer the adhesive film to a 100-μm PVC film with a cold laminating machine, put it in a constant temperature and humidity chamber (23 - 25 °C, 50% - 60% RH) and let it stand for 24 hours, cut it into different sizes and remove the release paper to obtain test samples;

[0157] Commercial products 1-2 are two different acrylate pressure-sensitive adhesive emulsions purchased on the market. Among them, commercial product 1 is AC8903(S) produced by Guangdong Yinyang New Environmental Materials Co., Ltd., and commercial product 2 is NX 2278 produced by BASF;

[0158] 2. Adhesion test:

[0159] In a temperature and humidity controlled chamber (23 - 25°C, 50% - 60% RH), stick a 1-inch-wide test sample onto a mirror-finish steel plate. After placing it for 20 minutes, use an adhesion tester to measure the 180° peel strength. The greater the peel strength, the better the adhesiveness of the waterborne acrylate pressure-sensitive adhesive emulsion. The test standard is PSTC-101; the unit is N / inch (Newton per inch), indicating how many Newtons the peel strength of a 1-inch-wide test sample is.

[0160] 3. Removability test:

[0161] In a temperature and humidity controlled chamber (23 - 25°C, 50% - 60% RH), stick a 1-inch-wide test sample onto a mirror-finish steel plate. Place it for 1 day, 7 days, 15 days, and 30 days respectively to conduct experiments on the same test sample with 4 different sticking times. Then use an adhesion tester to measure the 180° peel effect and observe the residual glue situation. If there is no residue of the test sample on the mirror-finish steel plate after the test sample is peeled off, it is recorded as "removable", indicating that the waterborne acrylate pressure-sensitive adhesive emulsion has good removability. If there is residue of the test sample on the mirror-finish steel plate after the test sample is peeled off, it is recorded as "residual glue", indicating that the waterborne acrylate pressure-sensitive adhesive emulsion has poor removability.

[0162] 4. Tack test:

[0163] Conduct the tack test in accordance with the test standard PSTC-6, and record the largest steel ball size (#) that the adhesive surface can hold. The larger the steel ball size (#) that can be held, the better the tack of the waterborne acrylate pressure-sensitive adhesive emulsion.

[0164] 5. Holding power test:

[0165] Stick a 1-inch-wide test sample onto the holding power test steel plate, cut off the excess part at one end so that the fitting area of the sample and the test plate is 1 inch × 1 inch, and connect a 1 kg weight to the other end using a hanging ring and hang it on a timer. Record the time (h) that the test sample can remain stuck to the test plate. The longer the time (h), the better the holding power of the waterborne acrylate pressure-sensitive adhesive emulsion. The test standard is PSTC-107.

[0166] 6. PVC shrinkage resistance test:

[0167] Attach a test sample with a size of 10 cm × 10 cm to an aluminum plate. Use a utility knife to cut a "plus" sign with a size of 5 cm × 5 cm in the center of the test sample, and then place it in an oven at 60 °C for aging for 50 h. Take it out and observe and measure the maximum separation distance (unit: mm) of the vertical and horizontal lines of the "plus" sign. And use this distance value (unit: mm) as the specific value of the maximum longitudinal shrinkage or maximum transverse shrinkage of the PVC shrinkage resistance of the waterborne acrylate pressure-sensitive adhesive emulsion. Moreover, the smaller the distance value (unit: mm), the better the PVC shrinkage resistance of the waterborne acrylate pressure-sensitive adhesive emulsion;

[0168] The experimental results are shown in the following table:

[0169] Table 1 Performance test results of waterborne acrylate pressure-sensitive adhesive emulsions of each example and comparative example

[0170]

[0171]

[0172] As can be seen from Table 1, the waterborne acrylate pressure-sensitive adhesive emulsion prepared by the present invention has good adhesiveness, removability and PVC shrinkage resistance after being coated on a PVC substrate.

[0173] From Example 1 and Comparative Example 1, it can be seen that the components in Monomer Composition A and Monomer Composition B can form cross-links between molecular chains, thereby increasing the polarity of the molecular chains and further enhancing the cohesive force of the polymer. In particular, in the preparation of the waterborne acrylate pressure-sensitive adhesive emulsion in Comparative Example 1, N-methylolacrylamide was not added to Monomer Composition A, and methyl methacrylate was used instead of methacrylic acid in Monomer Composition B, resulting in poor cohesive force of the polymer in the finally synthesized waterborne acrylate pressure-sensitive adhesive emulsion. Specifically, the removability, PVC shrinkage resistance and holding force of the waterborne acrylate pressure-sensitive adhesive emulsion are all poor.

[0174] From Example 2 and Comparative Example 2, it can be seen that the weight of Monomer Composition B should not be too large. When the weight ratio of Monomer Composition A to Monomer Composition B is less than 10:2, the cohesive force of the polymer in the synthesized waterborne acrylate pressure-sensitive adhesive emulsion is poor. Specifically, the adhesiveness, removability and PVC shrinkage resistance of the waterborne acrylate pressure-sensitive adhesive emulsion become worse.

[0175] It can be seen from Example 3 and Comparative Example 3 that when the raw material dosages for preparing the aqueous acrylate pressure-sensitive adhesive emulsion are the same, the segmented feeding process can improve the adhesiveness, removability, and PVC shrinkage resistance of the aqueous acrylate pressure-sensitive adhesive emulsion. Since segmented feeding was not carried out in Comparative Example 3, a single polymer was finally synthesized, resulting in the inability of the aqueous acrylate pressure-sensitive adhesive emulsion to simultaneously meet excellent adhesiveness, initial adhesion, and holding power. In Example 3 of the present invention, a specific segmented feeding process and formulation composition were used to synthesize an aqueous acrylate pressure-sensitive adhesive emulsion with different types of polymers. Through a simple method, the synthesized polymers have good molecular polarity, cohesion, and PVC shrinkage resistance, solving the problem that the adhesiveness and cohesion of traditional aqueous acrylate pressure-sensitive adhesive emulsions cannot be both achieved. The aqueous acrylate pressure-sensitive adhesive emulsion shows good adhesiveness, removability, and PVC shrinkage resistance when coated on a PVC substrate.

[0176] It can be seen from Example 1 and Comparative Example 4 that when the raw material dosages for preparing the aqueous acrylate pressure-sensitive adhesive emulsion are the same, compared with the aqueous acrylate pressure-sensitive adhesive emulsion synthesized by the segmented feeding method in Example 1, the sample synthesized by the seed emulsion polymerization process in Comparative Example 4 is a single-type polymer emulsion, while the segmented feeding process of the present invention can synthesize an aqueous acrylate pressure-sensitive adhesive emulsion with different types of polymers, achieving complementary and improved performance. Therefore, the adhesiveness, removability, and PVC shrinkage resistance of the aqueous acrylate pressure-sensitive adhesive emulsion synthesized by the seed emulsion polymerization method in Comparative Example 4 are all poor.

[0177] It can be seen from Example 2 and Comparative Example 5 that the weight of monomer composition B should not be too small. When the weight ratio of monomer composition A to monomer composition B is greater than 10:0.1, the adhesiveness, removability, and PVC shrinkage resistance of the synthesized aqueous acrylate pressure-sensitive adhesive emulsion are all worse than those of Example 2.

[0178] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A preparation method of an aqueous acrylate pressure-sensitive adhesive emulsion, characterized in that, It includes the following steps: S1. Provide acrylate pre-emulsion A and initiator solution B; S2. Drop part of acrylate pre-emulsion A into the initiator solution B and conduct a heating reaction to obtain polymer A emulsion; S3. Provide monomer composition B, mix the remaining part of acrylate pre-emulsion A and the monomer composition B to obtain acrylate pre-emulsion B; S4. Drop the acrylate pre-emulsion B into the polymer A emulsion and heat to conduct a reaction to obtain the aqueous acrylate pressure-sensitive adhesive emulsion; Among them, the acrylate pre-emulsion A contains the following components: water, emulsifier, initiator A and monomer composition A; the initiator solution B contains the following components: water, buffer and initiator B.

2. The preparation method of the aqueous acrylate pressure-sensitive adhesive emulsion according to claim 1, wherein, It includes at least one of the following (1)-(4): (1) In step S1, the acrylate pre-emulsion A includes the following components in parts by weight: 10-30 parts of water, 1-5 parts of emulsifier, 0-0.2 parts of chain transfer agent, 0.1-0.5 parts of initiator A, 60-85 parts of monomer composition A; (2) The emulsifier is at least one of sodium lauryl polyoxyethylene ether sulfate, sodium alkyl sulfosuccinate, and sodium dioctyl sulfosuccinate; (3) The initiator A is at least one of ammonium persulfate, potassium persulfate, and sodium persulfate; (4) Based on 100 parts by weight of the monomer composition A, it includes the following components in parts by weight: 65-90 parts of soft monomer, 2-20 parts of hard monomer, 2-15 parts of functional monomer A; the soft monomer is at least one of butyl acrylate and isooctyl acrylate; the hard monomer is at least one of methyl methacrylate and styrene; the functional monomer A contains N-methylolacrylamide and monomer X, and the monomer X includes at least one of acrylic acid and 2-hydroxyethyl methacrylate.

3. The preparation method of the aqueous acrylate pressure-sensitive adhesive emulsion according to claim 2, wherein, The chain transfer agent is at least one of dodecyl mercaptan, isooctyl 3-mercaptopropionate, and α-methylstyrene dimer.

4. The preparation method of the aqueous acrylate pressure-sensitive adhesive emulsion according to claim 1, characterized in that, It includes at least one of the following (1)-(8): (1) In the initiator solution B, the weight ratio of water, buffer, and initiator B is 100:(0.1-0.3):(0.5-1.5); (2) The weight ratio of initiator A and initiator B is 1:(0.5-3); (3) In the initiator solution B, the buffer is at least one of sodium bicarbonate, sodium carbonate, sodium acetate, and sodium bisulfite; (4) In the initiator solution B, the initiator B is at least one of ammonium persulfate, potassium persulfate, and sodium persulfate; (5) The initiator solution B is obtained by heating the water and buffer and then adding initiator B, and the heating temperature is 75-85°C; (6) In step S2, the weight ratio of the part of acrylate pre-emulsion A to the acrylate pre-emulsion A is (0.7-0.9):1; (7) In step S2, the heating reaction temperature is 75-85°C; (8) In step S2, the dropping time of the part of acrylate pre-emulsion A is 2-5 h.

5. The preparation method of the aqueous acrylate pressure-sensitive adhesive emulsion according to claim 1, characterized in that, It includes at least one of the following (1)-(4): (1) In step S3, the weight ratio of the remaining acrylate pre-emulsion A to the acrylate pre-emulsion A is (0.1 - 0.3):1; (2) The weight ratio of monomer composition A to monomer composition B in the acrylate pre-emulsion A is 10:(0.1 - 2); (3) The weight ratio of monomer composition A to monomer composition B in the remaining acrylate pre-emulsion A is 10:(0.33 - 20); (4) In step S3, based on 100 parts by weight of monomer composition B, it includes the following components in parts by weight: 30 - 80 parts of acrylate monomer, 20 - 70 parts of acrylic functional monomer; Among them, the acrylate monomer is at least one of C1 - C8 alkyl acrylate and C1 - C8 alkyl methacrylate; The acrylic functional monomer is an acrylate containing at least one functional group among carboxyl, hydroxyl, acyl, amino, and ureido groups.

6. The preparation method of the aqueous acrylate pressure-sensitive adhesive emulsion according to claim 5, characterized in that It includes at least one of the following (1) - (4): (1) The C1 - C8 alkyl acrylate is at least one of methyl acrylate, ethyl acrylate, butyl acrylate, and isooctyl acrylate; (2) The C1 - C8 alkyl methacrylate is at least one of methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, and isooctyl methacrylate; (3) The acrylic functional monomer is at least one of acrylic acid, acrylonitrile, methacrylic acid, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, acrylamide, β-acryloyloxypropionic acid, and ethyl 2-(methacryloyloxy)ethylcarbamate; (4) In step S3, based on 100 parts by weight of monomer composition B, it includes the following components in parts by weight: 50 - 80 parts of acrylate monomer, 20 - 50 parts of acrylic functional monomer.

7. The preparation method of the aqueous acrylate pressure-sensitive adhesive emulsion according to claim 1, characterized in that, It includes at least one of the following (1) - (2): (1) In step S4, the temperature of the reaction is 75 - 85°C; (2) After heating for the reaction in step S4, it further includes cooling, adjusting the pH, and adding additives.

8. The preparation method of the aqueous acrylate pressure-sensitive adhesive emulsion according to claim 7, characterized in that, It includes at least one of the following (1) - (2): (1) The weight ratio of the acrylate pre-emulsion A to the additive is 1:(0.004 - 0.02); (2) The additive is at least one of defoamer, wetting agent, and preservative.

9. An aqueous acrylate pressure-sensitive adhesive emulsion, characterized in that, Prepared by the preparation method according to any one of claims 1 - 8.

10. An application of the aqueous acrylate pressure-sensitive adhesive emulsion as claimed in claim 9 in PVC.

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