Water-soluble polymeric pressure-sensitive adhesive and label material comprising pressure-sensitive adhesive

Abstract

The present invention provides a water-soluble polymeric pressure-sensitive adhesive and a label material comprising the pressure-sensitive adhesive. The pressure-sensitive adhesive has a strong adhesive force when applied to a label material, can easily be cut without sticking upon a die-cutting process on the label material, and has good repeelability. The pressure-sensitive adhesive is composed of 4-6 parts of a water-soluble polyester, 16-18 parts of C1-C4 alkyl methacrylate, 16-18 parts of C4-C8 alkyl acrylate, 2-8 parts of ureido (meth)acrylate, and 4-5 parts of cycloalkyl methacrylate, wherein R1 is H or methyl, R2 is a linear or cyclic ureido group containing 3-5 carbon atoms, and the cycloalkyl methacrylate is a C5-C20 cycloalkyl ester, and the water-soluble polyester is prepared from 1-5 parts of a sulfonate for polyester modification, 10-15 parts of hydroxylalkyl (meth)acrylate, 60-80 parts of terephthalic acid, and 20-30 parts of ethylene glycol.

Description

Water-soluble polymeric pressure-sensitive adhesive and label material containing the same Technical Field

[0001] The present invention relates to the technical field of labels, and in particular to a water-soluble polymeric pressure-sensitive adhesive and a label material containing the pressure-sensitive adhesive. Background Art

[0002] In recent years, due to the rapid development in packaging, transportation, materials, etc., the demand for label products has continued to expand, and the performance requirements for label products have also continued to change. A well-known and commonly used label material includes a polyester-based surface material, a water-based polymer pressure-sensitive adhesive, and a substrate that are bonded to each other from top to bottom. The production process is generally as follows: pressure-sensitive adhesive is applied to the surface material, and after drying, the substrate and the surface material are compounded to obtain the label material; the label material is further die-cut into multiple finished labels of set sizes. During die-cutting, the surface material and the pressure-sensitive adhesive layer must be cut off, and the substrate needs to maintain its integrity. When in use, the surface material and pressure-sensitive adhesive are removed from the substrate and attached to the surface of the application object. Technical issues

[0003] Currently, acrylate polymers obtained by copolymerizing various types of acrylate monomers are a very important type of pressure-sensitive adhesive. After years of development, scientific researchers have continuously adjusted the polymerization formula and polymerization process of acrylate pressure-sensitive adhesive products, and introduced a variety of functional monomers to improve their performance. Despite this, there are still a series of problems when this type of pressure-sensitive adhesive is used for label materials: for example, the compatibility of the pressure-sensitive adhesive with the label surface material is poor, and the adhesion is insufficient, resulting in a certain degree of adhesion to the base material during the labeling process, making it impossible to complete the labeling quickly, and some residual glue will remain on the base paper after labeling, affecting the recycling of the base paper. In addition, when the label product is die-cut, due to the strong resilience of the pressure-sensitive adhesive, it will rebound to its original state after die-cutting. At this time, the glue at the incision position will flow to the incision position to form adhesion, resulting in adhesion during labeling. Technical Solutions

[0004] In view of this, the present invention provides a water-soluble polymeric pressure-sensitive adhesive, which has strong adhesion when used for label materials, is easy to cut and does not stick when the label material is die-cut, has good re-peelability, and will not stick to the base material when removing the label, so that residual adhesive will not be left on the base paper.

[0005] The present invention also provides a label material comprising the water-soluble polymeric pressure-sensitive adhesive.

[0006] As a first aspect of the present invention, the present invention provides a water-based polymer pressure-sensitive adhesive, which is polymerized from the following raw materials in parts by weight: 4-6 parts of water-soluble polyester, 16-18 parts of C1-C4 alkyl methacrylate, 16-18 parts of C4-C8 alkyl acrylate, and ureido (meth)acrylate.1 CH-COOR 2 2-8 parts, 4-5 parts of cycloalkyl methacrylate, wherein R 1 is H or methyl, R 2 is a linear or cyclic urea group containing 3 to 5 carbon atoms, and the cycloalkyl ester of methacrylic acid is C5-C 20 Cycloalkyl esters;

[0007] The water-soluble polyester is obtained by polymerizing the following raw materials in parts by weight: 1-5 parts of sulfonate for polyester modification, hydroxyalkyl (meth)acrylate CHR 3 CH-COOR 4 OH 10-15 parts, terephthalic acid 60-80 parts, ethylene glycol 20-30 parts, of which R 3 is H or methyl, R 4 It is a straight or branched chain alkylene group containing 2 to 5 carbon atoms.

[0008] In the present invention, the term "C n -C m "Alkyl" refers to a radical of a linear or branched saturated hydrocarbon radical having n to m carbon atoms. For example, the term C1-C4 alkyl refers to a radical of a linear or branched saturated hydrocarbon radical having 1 to 4 carbon atoms, and C4-C8 alkyl refers to a radical of a linear or branched saturated hydrocarbon radical having 4 to 8 carbon atoms. Examples of C1-C4 alkyl are methyl, ethyl, propyl, 1-methylethyl, butyl, 1-methylpropyl, 2-methylpropyl or 1,1-dimethylethyl. Examples of C4-C8 alkyl include, but are not limited to, n-butyl, sec-butyl, isobutyl, tert-butyl, 2-methylpropyl, 1,1-dimethylethyl (tert-butyl), pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 2,2-dimethylpropyl, 1-ethylpropyl As used herein, the term "cycloalkyl" refers to a monocyclic or bicyclic alicyclic group which is unsubstituted or substituted with 1, 2, 3 or 4 methyl groups, wherein the cycloalkyl group is a C5-C5 alkyl group, a C5-C5 alkyl group, a C5-C5 alkyl group, a C5-C5 alkyl group, a C5-C5 alkyl group, a C5-C5 alkyl group, a C5-C5 alkyl group, a C5-C5 alkyl group, a C5-C5 alkyl group, a C5-C5 alkyl group, a C5-C5 alkyl group, a C5-C5 alkyl group, a C5-C5 alkyl group, a C5-C5 alkyl group, a C5-C5 alkyl group, a C5-C5 alkyl group, a C5-C5 alkyl group, a C5-C5 alkyl group, a C5-C5 alkyl group, a C5-C5 alkyl group, a C5-C5 alkyl group, a C5-C5 alkyl group, 20 The total number of carbon atoms in the cycloalkyl group is 5 to 20, C5-C 10 The total number of carbon atoms in the cycloalkyl group is 5 to 10. 20Examples of cycloalkyl groups include, but are not limited to, cyclopentyl, cyclohexyl, methylcyclohexyl, dimethylcyclohexyl, cycloheptyl, cyclooctyl, cyclododecyl, cyclohexadecyl, norbornyl (=bicyclo[2.2.1]heptyl), and isobornyl (=1,7,7-trimethylbicyclo[2.2.1]heptyl).

[0009] Preferably, the (meth)acrylate urea CHR 1 CH-COOR 2 It is ethylene urea ethoxy methacrylate.

[0010] Preferably, the hydroxyalkyl (meth)acrylate CHR 3 CH-COOR 4 OH is 2-hydroxyethyl acrylate, 3-hydroxypropyl methacrylate, 2-hydroxypropyl acrylate or 4-hydroxybutyl acrylate, more preferably 4-hydroxybutyl acrylate.

[0011] The sulfonate used for polyester modification can be selected from the sulfonates commonly used in the field of water-soluble polyesters in the prior art for water-soluble modification of polyesters, such as sodium bis(hydroxyethyl)isophthalate-5-sulfonate.

[0012] Preferably, the cycloalkyl ester of methacrylic acid can be a cycloalkyl ester of a monocyclic or bicyclic structure, preferably a C5-C 10 Cycloalkyl esters, such as isobornyl methacrylate or norbornyl methacrylate.

[0013] The water-soluble polyester and acrylic polymer can be prepared using methods commonly used in the art. Specific process parameters can be determined by technicians through experiments. The viscosity of the water-soluble polyester is preferably 5000-10000 mPa·s. Specifically, the following method for preparing the water-soluble polyester can be selected: a sulfonate used for polyester modification, a hydroxyalkyl (meth)acrylic acid ester CHR 3 CH-COOR 4 OH, terephthalic acid, and ethylene glycol are placed in a reactor and heated to 120-125°C. A polycondensation initiator is added to initiate an esterification reaction. After 3-3.5 hours of reaction, the temperature is raised to 210-215°C for a polycondensation reaction, which is then continued for 5-5.5 hours to obtain a water-soluble polyester. A conventional polycondensation initiator, such as antimony ethylene glycol, can be used.

[0014] Specifically, the preparation method of the water-based polymer pressure-sensitive adhesive is:

[0015] (1) mixing a water-soluble polyester with a C1-C4 alkyl methacrylate, a C4-C8 alkyl acrylate, a ureido acrylate, a cycloalkyl methacrylate, and a first portion of deionized water, and stirring and emulsifying to obtain a monomer pre-emulsion having a solid content of 30% to 50%;

[0016] (2) After heating 50-100 parts by weight of the second portion of deionized water, 10%-20% of the monomer pre-emulsion obtained in step (1) is added to carry out a free radical polymerization reaction, and then the remaining pre-emulsion is added dropwise to carry out a free radical polymerization reaction. The resulting product has a viscosity of 100-500 mPa·s.

[0017] Furthermore, the preparation method of the water-based polymer pressure-sensitive adhesive is:

[0018] (1) mixing a water-soluble polyester with a C1-C4 alkyl methacrylate, a C4-C8 alkyl acrylate, a ureido acrylate, a cycloalkyl methacrylate, the first portion of deionized water, and a free radical initiator, and stirring and emulsifying to obtain a monomer pre-emulsion, wherein the weight of the initiator is 0.3% to 0.8% of the total weight of the water-soluble polyester, the C1-C4 alkyl methacrylate, the C4-C8 alkyl acrylate, the ureido acrylate, and the cycloalkyl methacrylate;

[0019] (2) Heat the second portion of deionized water to 78-82°C, add 10%-20% of the monomer pre-emulsion obtained in step (1), react for 15-25 minutes, then dropwise add the remaining monomer pre-emulsion over a period of 2-5 hours. After the addition is complete, heat at 80-85°C for 1-2 hours; cool to below 45°C, adjust the pH to 7-8, finally add a wetting agent and a defoaming agent, stir evenly, and filter to obtain a water-based polymer pressure-sensitive adhesive. The resulting pressure-sensitive adhesive has a concentration of 35%-42%. Sometimes, a small amount of free radical initiator can be added during the heat-retention reaction stage to ensure complete monomer reaction.

[0020] The free radical initiator, wetting agent, and defoaming agent can be selected from conventional methods in the art. For example, the free radical initiator can be ammonium persulfate or potassium persulfate alone; or a redox system initiator. Of course, as a general rule, the oxidizing agent and reducing agent in the redox system should be added separately. In this case, the monomer pre-emulsion obtained in step (1) can contain at most one of them, for example, the oxidizing agent; the wetting agent can be an acetylenic diol or an organosilicon; and the defoaming agent can be a mineral oil or an organosilicon.

[0021] As a second aspect of the present invention, the present invention further provides a label material comprising the above-mentioned water-soluble polymeric pressure-sensitive adhesive, comprising a polyester-based surface material and a water-based polymeric pressure-sensitive adhesive bonded to each other.

[0022] In an embodiment of the present invention, the surface material is polymerized from the following raw materials in parts by weight: 40-60 parts of polyethylene terephthalate-1,4-cyclohexanedimethanol (PETG), 15-35 parts of polyethylene terephthalate (PET), 15-20 parts of polycarbonate, and 0.1-1.0 parts of a lubricant. Specifically, the PET, PETG, polycarbonate, and lubricant are mixed and melted, cast into a sheet, and then stretched uniaxially or biaxially, followed by rapid cooling and shaping to produce the surface material. Preferably, the sheet is cast and biaxially stretched 3-5 times, followed by cooling and shaping at 25-55°C to produce the surface material.

[0023] Among them, as a preferred embodiment, the number average molecular weight of PETG is 50,000 to 80,000, and the intrinsic viscosity is 0.80 to 0.85 dl / g; the number average molecular weight of PET is 20,000 to 30,000, and the intrinsic viscosity is 0.62 to 0.67 dl / g; and the number average molecular weight of polycarbonate is 20,000 to 35,000.

[0024] The lubricant can be any substance known and commonly used in the art, preferably silicon dioxide, glass beads, kaolin or aluminum oxide.

[0025] When making label materials according to the existing technology, silicon is coated on the base material, and the coating amount is controlled to be 0.1-0.5g / ㎡; the water-based polymer pressure-sensitive adhesive is coated on the surface material; after the surface material is dried, the base material and the surface material are composited into a label material, and the water-based polymer pressure-sensitive adhesive is located between the base material and the surface material; the label material is die-cut into multiple finished labels with set sizes.

[0026] The substrate can be made of materials commonly known in the art. For example, a method for preparing the substrate is as follows: polyethylene terephthalate is melted, cast into a sheet, biaxially stretched 2 times, and heat-set at 220°C. Beneficial effects

[0027] The technical solution provided by the present invention has the following advantages:

[0028] 1. The water-based polymer pressure-sensitive adhesive provided by the present invention can effectively improve the wettability, adhesion, and bonding of the water-based polymer pressure-sensitive adhesive to the surface material, so that the surface material and the pressure-sensitive adhesive are firmly attached together during the label removal process. The surface material with the pressure-sensitive adhesive is easily separated from the base material, and the label removal can be completed quickly, avoiding excessive adhesion to the base material that causes poor label removal. After the label is removed, no residual adhesive will be left on the base paper, avoiding affecting the base paper recycling. The inventors speculate that the reasons are as follows:

[0029] The water-based polymer pressure-sensitive adhesive of the present invention is modified by introducing a water-soluble polyester so that the molecular chain structure of the pressure-sensitive adhesive is similar to that of the polyester surface material of the label. Based on the principle of like dissolves like, its compatibility with the surface material is improved, thereby enhancing its wettability to the surface material. At the same time, the sulfonic acid groups in the water-soluble polyester are hydrophilic, which can further enhance the wettability of the water-based polymer pressure-sensitive adhesive, thereby enhancing the adhesion of the water-based polymer pressure-sensitive adhesive to the surface material.

[0030] Water-soluble polyesters have poor compatibility with acrylic polymers. Therefore, directly physically mixing the water-soluble polyester with the acrylic polymer, or polymerizing the acrylic monomer in the presence of the water-soluble polyester to obtain the acrylic polymer, using these two methods to modify the acrylic polymer pressure-sensitive adhesive with the water-soluble polyester, fails to resolve the compatibility issue between the two. The resulting pressure-sensitive adhesive mixture is prone to opacity and unevenness, both of which are unacceptable during the use of label materials. The present invention cleverly introduces a (meth)acrylate hydroxyl ester monomer into the water-soluble polyester, thereby introducing a double bond structure into the water-soluble polyester. The resulting water-soluble polyester can undergo a free radical copolymerization reaction with the acrylic monomer. The polyester structure thereby covalently binds to the acrylic polymer, resolving the compatibility issue between the two and significantly improving the wettability and adhesion of the pressure-sensitive adhesive to the polyester-based surface material. The resulting pressure-sensitive adhesive is transparent, uniform, and has reliable and stable performance.

[0031] We successfully selected urea acrylates with appropriate copolymerization activity and introduced urea structures into waterborne polymer pressure-sensitive adhesives. The active hydrogen (H connected to nitrogen) in the urea acrylates can form hydrogen bonds with ester groups in other components of the waterborne polymer pressure-sensitive adhesive and ester groups in the face material, thereby increasing the adhesive's adhesion and adhesion to the face material. Furthermore, when the urea-containing structure is a heterocyclic structure, it significantly improves the aging resistance of the pressure-sensitive adhesive.

[0032] 2. The water-based polymer pressure-sensitive adhesive provided by the present invention can provide intermolecular forces based primarily on hydrogen bonds (as described above), with a high molecular crosslinking density and numerous crosslinking points, which can enhance the internal crosslinking strength and improve the cohesive force of the pressure-sensitive adhesive. The cycloalkyl methacrylate has a strong inhibitory effect on the movement of polymer chain segments, thereby enhancing the hardness of the pressure-sensitive adhesive and reducing its rebound fluidity. When used as a label adhesive, the adhesive does not adhere to the die-cutting process, preventing rebound after die-cutting, flowing toward the cut position to cause adhesion, and avoiding the situation where two adjacent labels adhere to each other after die-cutting. Traditional labels must be equipped with a waste discharge area due to the problem of adhesion between adjacent labels after die-cutting, resulting in a large amount of substrate and glue waste. However, when the water-based polymer pressure-sensitive adhesive provided by the present invention is used in labels, adjacent labels are not easily adhered to each other during the die-cutting process, so a waste discharge area can be eliminated during label die-cutting, achieving zero label waste. It can also avoid the problem of label assembly failure due to adhesion between adjacent labels during use, reducing label waste during use. Best Mode for Carrying Out the Invention

[0033] The technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0034] In the specific implementation of the present invention, the raw materials used are as follows: methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, butyl acrylate, 2-isooctyl acrylate, ethylene urea ethoxy methacrylate, isobornyl methacrylate, norbornyl methacrylate, 4-hydroxybutyl acrylate, industrial grade, Shanghai Yongzheng Chemical Co., Ltd.; terephthalic acid, industrial grade, Suzhou Suyuxuan Plastic Co., Ltd.; sodium bis(hydroxyethyl)isophthalate-5-sulfonate, industrial grade, Jingmen Dongxin Biotechnology Co., Ltd.; polyethylene terephthalate (PET), molecular weight 72000, polyethylene terephthalate-1,4-cyclohexanedimethanol ester (PETG), Molecular weight is 75,000, industrial grade, Suzhou Aokai Polymer Materials Co., Ltd.; polycarbonate, industrial grade, Nantong Xingchen Synthetic Materials Co., Ltd.; ethylene glycol, lubricant (including silica, glass beads, kaolin or aluminum oxide), chemically pure, commercially available; ammonium persulfate, potassium persulfate, industrial grade, Aijian Degussa (Shanghai) Co., Ltd.; acetylene glycol wetting agent 104E, industrial grade, Shanghai Sangjing Chemical Co., Ltd.; silicone wetting agent 122, industrial grade, Zhuhai Xiande New Materials Co., Ltd.; silicone defoamer TSA-830, industrial grade, Jiangsu Tengda Additives Co., Ltd.; mineral oil defoamer A-10, industrial grade, Tianjin Hepfer New Materials Co., Ltd.

[0035] As a first aspect of the present invention, the present invention provides a water-based polymer pressure-sensitive adhesive, which is polymerized from the following raw materials in parts by weight: 4-6 parts of water-soluble polyester, 16-18 parts of C1-C4 alkyl methacrylate, 16-18 parts of C4-C8 alkyl acrylate, and ureido (meth)acrylate. 1 CH-COOR 2 2-8 parts, 4-5 parts of cycloalkyl methacrylate, wherein R 1 is H or methyl, R 2 is a linear or cyclic urea group containing 3 to 5 carbon atoms, and the cycloalkyl ester of methacrylic acid is C5-C 20 Cycloalkyl esters;

[0036] The water-soluble polyester is obtained by polymerizing the following raw materials in parts by weight: 1-5 parts of sulfonate for polyester modification, hydroxyalkyl (meth)acrylate CHR 3 CH-COOR 4 OH 10-15 parts, terephthalic acid 60-80 parts, ethylene glycol 20-30 parts, of which R 3 is H or methyl, R 4 is a linear or branched alkylene group containing 2 to 5 carbon atoms. Preferably, 3 parts of sulfonate for polyester modification, hydroxyalkyl (meth)acrylate CHR 3 CH-COOR 4OH 15 parts, terephthalic acid 80 parts, ethylene glycol 20 parts.

[0037] Preferably, the hydroxyalkyl (meth)acrylate CHR 3 CH-COOR 4 OH is 2-hydroxyethyl acrylate, 3-hydroxypropyl methacrylate, 2-hydroxypropyl acrylate or 4-hydroxybutyl acrylate, more preferably 4-hydroxybutyl acrylate.

[0038] The sulfonate used for polyester modification can be selected from the sulfonates commonly used in the field of water-soluble polyesters in the prior art for water-soluble modification of polyesters, such as sodium bis(hydroxyethyl)isophthalate-5-sulfonate.

[0039] The C1-C4 alkyl methacrylate includes, but is not limited to, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, sec-butyl methacrylate, isobutyl methacrylate, or tert-butyl methacrylate, particularly methyl methacrylate. The C1-C4 alkyl methacrylate accounts for 16 to 18 parts by weight of the raw material, preferably 17 parts by weight.

[0040] The C4-C8 alkyl acrylate includes, but is not limited to, at least one of butyl acrylate, pentyl acrylate, heptyl acrylate, and isooctyl acrylate, particularly butyl acrylate and / or isooctyl acrylate. The C4-C8 alkyl acrylate accounts for 16-18 parts by weight, preferably 17 parts, of the raw material.

[0041] Preferably, the (meth)acrylate urea CHR 1 CH-COOR 2 It is ethylene urea ethoxy methacrylate. The (meth)acrylate urea ester CHR 1 CH-COOR 2 The weight proportion in the raw materials is 2 to 8 parts, preferably 5 parts.

[0042] Preferably, the cycloalkyl ester of methacrylic acid can be a cycloalkyl ester of a monocyclic or bicyclic structure, preferably a C5-C 10 Cycloalkyl ester, such as isobornyl methacrylate or norbornyl methacrylate. The weight proportion of the cycloalkyl methacrylate in the raw material is 4 to 5 parts, preferably 5 parts.

[0043] The water-soluble polyester and acrylic polymer can be prepared using methods commonly used in the art. Specific process parameters can be determined by technicians through experiments. The viscosity of the water-soluble polyester is preferably 5000-10000 mPa·s. Specifically, the following method for preparing the water-soluble polyester can be selected: a sulfonate used for polyester modification, a hydroxyalkyl (meth)acrylic acid ester CHR 3 CH-COOR 4 OH, terephthalic acid, and ethylene glycol are placed in a reactor and heated to 120-125°C. A polycondensation initiator is added to initiate an esterification reaction. After 3-3.5 hours of reaction, the temperature is raised to 210-215°C for a polycondensation reaction, which is then continued for 5-5.5 hours to obtain a water-soluble polyester. A conventional polycondensation initiator, such as antimony ethylene glycol, can be used.

[0044] Specifically, the preparation method of the water-based polymer pressure-sensitive adhesive is:

[0045] (1) mixing a water-soluble polyester with a C1-C4 alkyl methacrylate, a C4-C8 alkyl acrylate, a ureido acrylate, a cycloalkyl methacrylate, and a first portion of deionized water, and stirring and emulsifying to obtain a monomer pre-emulsion having a solid content of 30% to 50%;

[0046] (2) After heating 50-100 parts by weight of the second portion of deionized water, 10%-20% of the monomer pre-emulsion obtained in step (1) is added to carry out a free radical polymerization reaction, and then the remaining pre-emulsion is added dropwise to carry out a free radical polymerization reaction. The resulting product has a viscosity of 100-500 mPa·s.

[0047] As is common knowledge in the art, the free radical polymerization reaction described above requires the addition of a free radical initiator. The method of adding the free radical initiator can be determined by a technician based on actual needs. The free radical initiator can be added in step (1) as part of the monomer pre-emulsion and added to the reaction system in step (2). Alternatively, the free radical initiator can be added dropwise simultaneously with the monomer pre-emulsion in step (2) or separately. This will not be described in detail here.

[0048] Furthermore, the preparation method of the water-based polymer pressure-sensitive adhesive is:

[0049] (1) mixing a water-soluble polyester with a C1-C4 alkyl methacrylate, a C4-C8 alkyl acrylate, a ureido acrylate, a cycloalkyl methacrylate, the first portion of deionized water, and a free radical initiator, and stirring and emulsifying to obtain a monomer pre-emulsion, wherein the weight of the initiator is 0.3% to 0.8% of the total weight of the water-soluble polyester, the C1-C4 alkyl methacrylate, the C4-C8 alkyl acrylate, the ureido acrylate, and the cycloalkyl methacrylate;

[0050] (2) Heat the second portion of deionized water to 78-82°C, add 10%-20% of the monomer pre-emulsion obtained in step (1), react for 15-25 minutes, then dropwise add the remaining monomer pre-emulsion over a period of 2-5 hours. After the addition is complete, heat at 80-85°C for 1-2 hours; cool to below 45°C, adjust the pH to 7-8, finally add a wetting agent and a defoaming agent, stir evenly, and filter to obtain a water-based polymer pressure-sensitive adhesive. The resulting pressure-sensitive adhesive has a concentration of 35%-42%. Sometimes, a small amount of free radical initiator can be added during the heat-retention reaction stage to ensure complete monomer reaction.

[0051] The free radical initiator, wetting agent, and defoaming agent can be selected from conventional methods in the art. For example, the free radical initiator can be ammonium persulfate or potassium persulfate alone; or a redox system initiator. Of course, as a general rule, the oxidizing agent and reducing agent in the redox system should be added separately. In this case, the monomer pre-emulsion obtained in step (1) can contain at most one of them, for example, the oxidizing agent; the wetting agent can be an acetylenic diol or an organosilicon; and the defoaming agent can be a mineral oil or an organosilicon.

[0052] The viscosity of the water-soluble polyester and water-based polymer pressure-sensitive adhesive was measured using a commercially available rotational viscometer. The viscosity described in the following examples was measured using an NDJ-5S digital rotational viscometer manufactured by Shanghai Jingqi Instrument Co., Ltd.

[0053] As a second aspect of the present invention, the present invention further provides a label material comprising the above-mentioned water-soluble polymeric pressure-sensitive adhesive, comprising a polyester-based surface material and a water-based polymeric pressure-sensitive adhesive bonded to each other. Modes for Carrying Out the Invention

[0054] Example 1

[0055] This embodiment provides a water-based polymer pressure-sensitive adhesive, including the following raw materials: 50g of water-soluble polyester, 170g of methyl methacrylate, 70g of butyl acrylate, 100g of isooctyl acrylate, 50g of ethylene urea ethoxy methacrylate, and 50g of isobornyl methacrylate.

[0056] The preparation method of the water-soluble polyester is as follows: 70 g of terephthalic acid, 20 g of ethylene glycol, 3 g of sodium bis(hydroxyethyl)isophthalate-5-sulfonate, and 15 g of 4-hydroxybutyl acrylate are placed in a reactor, the temperature is raised to 125° C., 2 g of ethylene glycol antimony initiator is added to carry out an esterification reaction, and after reacting for 3 hours, the temperature is raised to 215° C. for a polycondensation reaction. After reacting for 5 hours, the water-soluble polyester is obtained by discharging the product, which has a viscosity of 6500 mPa·s.

[0057] In this embodiment, the specific preparation method of the water-based polymer pressure-sensitive adhesive includes the following steps:

[0058] (1) 50 g of water-soluble polyester, 170 g of methyl methacrylate, 70 g of butyl acrylate, 100 g of 2-isooctyl acrylate, 50 g of ethylene urea ethoxy methacrylate, 50 g of isobornyl methacrylate, 700 g of deionized water, and 2 g of ammonium persulfate were mixed, and the mixture was stirred and emulsified to obtain a monomer pre-emulsion having a solid content of 38%;

[0059] (2) 100 g of deionized water was heated to 80 ° C, 73.5 g of the monomer pre-emulsion prepared in step (1) was added, and the mixture was reacted for 20 min. The remaining monomer pre-emulsion was added dropwise over 4 h. After the addition was completed, the mixture was kept at 80 ° C for 1 h. The temperature was lowered to below 45 ° C, a pH regulator was added to adjust the pH value of the emulsion to 7-8, and finally 1 g of an acetylene glycol wetting agent and 1 g of an organosilicon defoaming agent were added. The mixture was stirred evenly and filtered to obtain a water-based polymer pressure-sensitive adhesive with a concentration of 35% and a viscosity of 150 mPa·s.

[0060] Preparation of label material: Silicone is coated on the base material at a controlled coating weight of 0.35g / ㎡. The aforementioned water-based polymer pressure-sensitive adhesive is applied to the face material. After drying, the base and face materials are laminated to form the label material. The label material is die-cut into multiple finished labels of a predetermined size. The face material is prepared by the following method: (by weight) 50 parts amorphous transparent or white PETG, 30 parts PET, 19.5 parts polycarbonate, and 0.5 parts lubricant are mixed and melted, cast into sheets, biaxially stretched at 4.4 times, and rapidly cooled at 30°C to set the shape. The lubricant is aluminum oxide; the base material is melted polyethylene terephthalate, cast into sheets, biaxially stretched at 2 times, and heat-set at 220°C.

[0061] Example 2

[0062] This embodiment provides a water-based polymer pressure-sensitive adhesive, including the following raw materials: 50g of water-soluble polyester, 170g of methyl methacrylate, 70g of butyl acrylate, 100g of isooctyl acrylate, 30g of ethylene urea ethoxy methacrylate, and 50g of isobornyl methacrylate.

[0063] The preparation method of the water-soluble polyester is as follows: 70 g of terephthalic acid, 20 g of ethylene glycol, 3 g of sodium bis(hydroxyethyl)-5-sulfonate isophthalate, and 15 g of 4-hydroxybutyl acrylate are placed in a reactor, the temperature is raised to 125° C., 2 g of ethylene glycol antimony initiator is added to carry out an esterification reaction, and after reacting for 3 hours, the temperature is raised to 215° C. for a polycondensation reaction. After reacting for 5 hours, the water-soluble polyester is obtained by discharging the product, which has a viscosity of 7600 mPa·s.

[0064] In this embodiment, the specific preparation method of the water-based polymer pressure-sensitive adhesive includes the following steps:

[0065] (1) 50 g of water-soluble polyester, 170 g of methyl methacrylate, 70 g of butyl acrylate, 100 g of isooctyl acrylate, 30 g of ethylene urea ethoxy methacrylate, 50 g of isobornyl methacrylate, 580 g of deionized water, and 2 g of ammonium persulfate were mixed, and the mixture was stirred and emulsified to obtain a monomer pre-emulsion having a solid content of 40%;

[0066] (2) 80 g of deionized water was heated to 80 ° C, 73.5 g of the monomer pre-emulsion prepared in step (1) was added, and the mixture was reacted for 20 min. The remaining monomer pre-emulsion was added dropwise over 4 h. After the addition was completed, the mixture was kept at 80 ° C for 1 h. The temperature was lowered to below 45 ° C, a pH regulator was added to adjust the pH value of the emulsion to 7-8, and finally 1 g of an acetylene glycol wetting agent and 1 g of an organosilicon defoaming agent were added. The mixture was stirred evenly and filtered to obtain a water-based polymer pressure-sensitive adhesive with a concentration of 38% and a viscosity of 120 mPa·s.

[0067] Preparation of label material: Silicone is coated on the base material at a controlled coating weight of 0.35g / ㎡. The aforementioned water-based polymer pressure-sensitive adhesive is applied to the face material. After drying, the base and face materials are laminated to form the label material. The label material is die-cut into multiple finished labels of a predetermined size. The face material is prepared by the following method: (by weight) 50 parts amorphous transparent or white PETG, 30 parts PET, 19.5 parts polycarbonate, and 0.5 parts lubricant are mixed and melted, cast into sheets, biaxially stretched at 4.4 times, and rapidly cooled at 30°C to set the shape. The lubricant is silica; the base material is melted polyethylene terephthalate, cast into sheets, biaxially stretched at 2 times, and heat-set at 220°C.

[0068] Example 3

[0069] This embodiment provides a water-based polymer pressure-sensitive adhesive, including the following raw materials: 50g of water-soluble polyester, 170g of methyl methacrylate, 70g of butyl acrylate, 100g of isooctyl acrylate, 30g of ethylene urea ethoxy methacrylate, and 50g of isobornyl methacrylate.

[0070] The preparation method of the water-soluble polyester is as follows: 75 g of terephthalic acid, 20 g of ethylene glycol, 3 g of sodium bis(hydroxyethyl)-5-sulfonate isophthalate, and 13 g of 4-hydroxybutyl acrylate are placed in a reactor, the temperature is raised to 125° C., 2 g of ethylene glycol antimony initiator is added to carry out an esterification reaction, and after reacting for 3 hours, the temperature is raised to 215° C. for a polycondensation reaction. After reacting for 5 hours, the water-soluble polyester is obtained by discharging the product, which has a viscosity of 7500 mPa·s.

[0071] In this embodiment, the specific preparation method of the water-based polymer pressure-sensitive adhesive includes the following steps:

[0072] (1) 50 g of water-soluble polyester, 170 g of methyl methacrylate, 70 g of butyl acrylate, 100 g of isooctyl acrylate, 30 g of ethylene urea ethoxy methacrylate, 50 g of isobornyl methacrylate, 600 g of deionized water, and 2 g of ammonium persulfate were mixed, and the mixture was stirred and emulsified to obtain a monomer pre-emulsion having a solid content of 44%;

[0073] (2) 90 g of deionized water was heated to 80 ° C, 73.5 g of the monomer pre-emulsion prepared in step (1) was added, and the mixture was reacted for 20 min. The remaining monomer pre-emulsion was then added dropwise over a period of 4 h. After the addition was completed, the mixture was kept at 80 ° C for 1 h. The mixture was cooled to below 45 ° C, a pH regulator was added to adjust the pH value of the emulsion to 7-8, and finally 1 g of an acetylene glycol wetting agent and 1 g of an organosilicon defoaming agent were added. The mixture was stirred evenly and filtered to obtain a water-based polymer pressure-sensitive adhesive having a concentration of 40.5% and a viscosity of 180 mPa·s.

[0074] Preparation of the label material: Silicone is coated on the base material at a controlled silicon coating of 0.35 g / m2. The aforementioned water-based polymer pressure-sensitive adhesive is applied to the face material. After drying, the base and face materials are laminated to form the label material. The label material is then die-cut into multiple finished labels of a predetermined size. The face material is prepared by the following method: (by weight) 50 parts amorphous transparent or white PETG, 30 parts PET, 19.5 parts polycarbonate, and 0.5 parts lubricant are mixed and melted, cast into sheets, biaxially stretched at 4.4 times, and rapidly cooled at 30°C to set the shape. The lubricant is kaolin clay; the base material is melted polyethylene terephthalate, cast into sheets, biaxially stretched at 2 times, and heat-set at 220°C.

[0075] Example 4

[0076] This embodiment provides a water-based polymer pressure-sensitive adhesive, including the following raw materials: 50g of water-soluble polyester, 170g of methyl methacrylate, 70g of butyl acrylate, 100g of isooctyl acrylate, 50g of ethylene urea ethoxy methacrylate, and 50g of isobornyl methacrylate.

[0077] The preparation method of the water-soluble polyester is as follows: 75 g of terephthalic acid, 20 g of ethylene glycol, 3 g of sodium bis(hydroxyethyl)-5-sulfonate isophthalate, and 12 g of 4-hydroxybutyl acrylate are placed in a reactor, the temperature is raised to 125° C., 2 g of ethylene glycol antimony initiator is added to carry out an esterification reaction, and after reacting for 3 hours, the temperature is raised to 215° C. for a polycondensation reaction. After reacting for 5 hours, the water-soluble polyester is obtained by discharging the product, which has a viscosity of 7100 mPa·s.

[0078] In this embodiment, the specific preparation method of the water-based polymer pressure-sensitive adhesive includes the following steps:

[0079] (1) 50 g of water-soluble polyester, 170 g of methyl methacrylate, 70 g of butyl acrylate, 100 g of isooctyl acrylate, 50 g of ethylene urea ethoxy methacrylate, 50 g of isobornyl methacrylate, 620 g of deionized water, and 2 g of ammonium persulfate were mixed and stirred to obtain a monomer pre-emulsion having a solid content of 44%;

[0080] (2) 60 g of deionized water was heated to 80 ° C, 73.5 g of the monomer pre-emulsion prepared in step (1) was added, and the mixture was reacted for 20 min. The remaining monomer pre-emulsion was added dropwise over 4 h. After the addition was completed, the mixture was kept at 80 ° C for 1 h. The temperature was lowered to below 45 ° C, a pH regulator was added to adjust the pH value of the emulsion to 7-8, and finally 1 g of an acetylene glycol wetting agent and 1 g of an organosilicon defoaming agent were added. The mixture was stirred evenly and filtered to obtain a water-based polymer pressure-sensitive adhesive with a concentration of 41.8% and a viscosity of 190 mPa·s.

[0081] Preparation of label material: Silicone is coated on the base material at a controlled coating weight of 0.35g / ㎡. The aforementioned water-based polymer pressure-sensitive adhesive is applied to the face material. After drying, the base and face materials are laminated to form the label material. The label material is die-cut into multiple finished labels of a predetermined size. The face material is prepared by the following method: (by weight) 50 parts amorphous transparent or white PETG, 30 parts PET, 19.5 parts polycarbonate, and 0.5 parts lubricant are mixed and melted, cast into sheets, biaxially stretched at 4.4 times, and rapidly cooled at 30°C to set the shape. The lubricant is silica; the base material is melted polyethylene terephthalate, cast into sheets, biaxially stretched at 2 times, and heat-set at 220°C.

[0082] Comparative Example 1

[0083] This comparative example provides a water-based polymer pressure-sensitive adhesive, comprising the following raw materials: 50 g of water-soluble polyester, 170 g of methyl methacrylate, 70 g of butyl acrylate, 100 g of isooctyl acrylate, and 50 g of isobornyl methacrylate.

[0084] The preparation method of the water-soluble polyester is as follows: 75 g of terephthalic acid, 20 g of ethylene glycol, 3 g of sodium bis(hydroxyethyl)-5-sulfonate isophthalate, and 15 g of 4-hydroxybutyl acrylate are placed in a reactor, the temperature is raised to 125° C., 2 g of ethylene glycol antimony initiator is added to carry out an esterification reaction, and after reacting for 3 hours, the temperature is raised to 215° C. for a polycondensation reaction. After reacting for 5 hours, the water-soluble polyester is obtained by discharging the product, which has a viscosity of 8500 mPa·s.

[0085] The specific preparation method of the water-based polymer pressure-sensitive adhesive comprises the following steps:

[0086] (1) 50 g of water-soluble polyester, 170 g of methyl methacrylate, 70 g of butyl acrylate, 100 g of isooctyl acrylate, 50 g of isobornyl methacrylate, 500 g of deionized water, and 2 g of ammonium persulfate were mixed, and the mixture was stirred and emulsified to obtain a monomer pre-emulsion having a solid content of 46.8%;

[0087] (2) 90 g of deionized water was heated to 80 ° C, 73.5 g of the monomer pre-emulsion prepared in step (1) was added, and the mixture was reacted for 20 min. The remaining monomer pre-emulsion was added dropwise over 4 h. After the addition was completed, the mixture was kept at 80 ° C for 1 h. The temperature was lowered to below 45 ° C, a pH regulator was added to adjust the pH value of the emulsion to 7-8, and finally 1 g of an acetylene glycol wetting agent and 1 g of an organosilicon defoaming agent were added. The mixture was stirred evenly and filtered to obtain a water-based polymer pressure-sensitive adhesive with a concentration of 42.7% and a viscosity of 210 mPa·s.

[0088] Preparation of label material: Silicone is coated on the base material at a controlled coating weight of 0.35g / ㎡. The aforementioned water-based polymer pressure-sensitive adhesive is applied to the face material. After drying, the base and face materials are laminated to form the label material. The label material is die-cut into multiple finished labels of a predetermined size. The face material is prepared by the following method: (by weight) 50 parts amorphous transparent or white PETG, 30 parts PET, 19.5 parts polycarbonate, and 0.5 parts lubricant are mixed and melted, cast into sheets, biaxially stretched at 4.4 times, and rapidly cooled at 30°C to set the shape. The lubricant is aluminum oxide. The base material is melted polyethylene terephthalate, cast into sheets, biaxially stretched at 2 times, and heat-set at 220°C.

[0089] Comparative Example 2

[0090] This comparative example provides a water-based polymer pressure-sensitive adhesive, comprising the following raw materials: 50 g of water-soluble polyester, 170 g of methyl methacrylate, 70 g of butyl acrylate, 100 g of isooctyl acrylate, 50 g of ethylene urea ethoxy methacrylate, and 50 g of isobornyl methacrylate.

[0091] The preparation method of the water-soluble polyester is as follows: 75 g of terephthalic acid, 20 g of ethylene glycol, and 3 g of sodium bis(hydroxyethyl)isophthalate-5-sulfonate are placed in a reactor, the temperature is raised to 125° C., 2 g of ethylene glycol antimony initiator is added to carry out an esterification reaction, and after reacting for 3 hours, the temperature is raised to 215° C. for a polycondensation reaction. After reacting for 5 hours, the water-soluble polyester is obtained by discharging the material with a viscosity of 8200 mPa·s.

[0092] The specific preparation method of the water-based polymer pressure-sensitive adhesive comprises the following steps:

[0093] (1) 50 g of water-soluble polyester, 170 g of methyl methacrylate, 70 g of butyl acrylate, 100 g of isooctyl acrylate, 50 g of ethylene urea ethoxy methacrylate, 50 g of isobornyl methacrylate, 600 g of deionized water, and 2 g of ammonium persulfate were mixed, and the mixture was stirred and emulsified to obtain a monomer pre-emulsion having a solid content of 47%;

[0094] (2) 100 g of deionized water was heated to 80 ° C, 73.5 g of the monomer pre-emulsion prepared in step (1) was added, and the mixture was reacted for 20 min. The remaining monomer pre-emulsion was then added dropwise over a period of 4 h. After the addition was completed, the mixture was kept at 80 ° C for 1 h. The mixture was cooled to 65 ° C and kept for 1 h. The mixture was cooled to below 45 ° C, a pH regulator was added to adjust the pH of the emulsion to 7-8, and finally 1 g of an acetylene glycol wetting agent and 1 g of an organosilicon defoaming agent were added. The mixture was stirred evenly and filtered to obtain a water-based polymer pressure-sensitive adhesive having a concentration of 43.5% and a viscosity of 240 mPa·s.

[0095] Preparation of the label material: Silicone is coated on the base material at a controlled silicon coating of 0.35 g / m2. The aforementioned water-based polymer pressure-sensitive adhesive is applied to the face material. After drying, the base and face materials are laminated to form the label material. The label material is then die-cut into multiple finished labels of a predetermined size. The face material is prepared by the following method: (by weight) 50 parts amorphous transparent or white PETG, 30 parts PET, 19.5 parts polycarbonate, and 0.5 parts lubricant are mixed and melted, cast into sheets, biaxially stretched at 4.4 times, and rapidly cooled at 30°C to set the shape. The lubricant is kaolin clay; the base material is melted polyethylene terephthalate, cast into sheets, biaxially stretched at 2 times, and heat-set at 220°C.

[0096] Comparative Example 3

[0097] This comparative example provides a water-based polymer pressure-sensitive adhesive, comprising the following raw materials: 50 g of water-soluble polyester, 170 g of methyl methacrylate, 70 g of butyl acrylate, 100 g of isooctyl acrylate, 50 g of modified hydroxyethyl acrylate urea (produced by Guangzhou Sanwang Chemical Materials Co., Ltd., model SW910), and 50 g of isobornyl methacrylate.

[0098] The preparation method of the water-soluble polyester is as follows: 75 g of terephthalic acid, 20 g of ethylene glycol, 3 g of sodium bis(hydroxyethyl)-5-sulfonate isophthalate, and 14 g of 4-hydroxybutyl acrylate are placed in a reactor, the temperature is raised to 125° C., 2 g of ethylene glycol antimony initiator is added to carry out an esterification reaction, and after reacting for 3 hours, the temperature is raised to 215° C. for a polycondensation reaction. After reacting for 5 hours, the water-soluble polyester is obtained by discharging the product, which has a viscosity of 7400 mPa·s.

[0099] The specific preparation method of the water-based polymer pressure-sensitive adhesive comprises the following steps:

[0100] (1) 50 g of water-soluble polyester, 170 g of methyl methacrylate, 70 g of butyl acrylate, 100 g of isooctyl acrylate, 50 g of modified hydroxyethyl acrylate urea, 50 g of isobornyl methacrylate, 680 g of deionized water, and 2 g of ammonium persulfate were mixed, and the mixture was stirred and emulsified to obtain a monomer pre-emulsion having a solid content of 44.2%;

[0101] (2) 80 g of deionized water was heated to 80 ° C, 73.5 g of the monomer pre-emulsion prepared in step (1) was added and reacted for 20 min, and the remaining monomer pre-emulsion was added dropwise within 4 h. After the addition was completed, the mixture was kept at 80 ° C for 1 h; the temperature was lowered to 65 ° C, and the mixture was kept at this temperature for 1 h; the temperature was lowered to below 45 ° C, a pH regulator was added to adjust the pH value of the emulsion to 7-8, and finally 1 g of an acetylene glycol wetting agent and 1 g of an organosilicon defoaming agent were added, the mixture was stirred evenly, and the mixture was filtered to obtain a water-based polymer pressure-sensitive adhesive with a concentration of 41.5% and a viscosity of 170 mPa·s.

[0102] Preparation of label material: Silicone is coated on the base material at a controlled coating weight of 0.35g / ㎡. The aforementioned water-based polymer pressure-sensitive adhesive is applied to the face material. After drying, the base and face materials are laminated to form the label material. The label material is die-cut into multiple finished labels of a predetermined size. The face material is prepared by the following method: (by weight) 50 parts amorphous transparent or white PETG, 30 parts PET, 19.5 parts polycarbonate, and 0.5 parts lubricant are mixed and melted, cast into sheets, biaxially stretched at 4.4 times, and rapidly cooled at 30°C to set the shape. The lubricant is silica; the base material is melted polyethylene terephthalate, cast into sheets, biaxially stretched at 2 times, and heat-set at 220°C. Industrial Applicability

[0103] Application Experiment Examples

[0104] The label materials prepared in Examples 1-4 and the label materials prepared in Comparative Examples 1-3 were tested for initial tack, sustained tack, and 180° peel strength, respectively, and the degree of adhesion between two adjacent second label materials after die-cutting was observed. The test results are shown in Table 1.

[0105] Test method: Initial tack is measured in accordance with GB / T 31125-2014, Test method for initial tack of pressure-sensitive adhesive tapes (ring method); persistent tack is measured in accordance with GBT 4851-2014, Test method for persistent tack of adhesive tapes; and 180° peel strength is measured in accordance with GB / T 2792-2014, Test method for peel strength of adhesive tapes.

[0106] Table 1 Performance test results

[0107] Test Group Initial Adhesion N / 25mm Maintaining Adhesion 180° Peel Strength N / 25mm Anti-adhesion Example 1 16.3 > 1000h 14.8 Non-adhesion Example 2 16.8 > 1000h 14.1 Non-adhesion Example 3 16.6 > 1000h 15.2 Non-adhesion Example 4 15.8 > 1000h 14.9 Non-adhesion Comparative Example 1 20.1 < 800h 10.6 Partial Adhesion Comparative Example 2 15.7 < 800h 10.5 Partial Adhesion Comparative Example 3 18.9 < 800h 11.2 Partial Adhesion

[0108] As can be seen from the table above, in Comparative Examples 1 and 3, when the water-based polymer pressure-sensitive adhesives lacked urea monomers or were replaced with different urea monomers, the water-based polymer pressure-sensitive adhesives had low crosslinking strength and cohesive force, resulting in high initial tack but low sustained tack and peel strength. This caused the label to adhere to the substrate during labeling. In Comparative Example 2, the water-based polymer pressure-sensitive adhesive lacked 4-hydroxybutyl acrylate, resulting in poor wettability and low adhesion to the substrate. Consequently, the label had low sustained tack and peel strength, causing the label to adhere to the substrate during labeling. The label materials prepared in Examples 1-4 have a high compatibility between the water-based polymer pressure-sensitive adhesive and the surface material. The water-based polymer pressure-sensitive adhesive has good wettability, adhesion, and bonding to the surface material, high cross-linking strength, and high cohesion. This allows the label to obtain good initial tack, sustained tack, and peel strength, so that the surface material will not adhere to the base material during the labeling process, allowing for quick labeling. After labeling, no residual adhesive will remain on the base paper, thus preventing it from affecting base paper recycling. At the same time, by increasing the internal cross-linking strength, the water-based polymer pressure-sensitive adhesive improves the cohesive strength, thereby increasing the hardness of the pressure-sensitive adhesive and reducing its rebound fluidity. This prevents adhesive strands from sticking together during the die-cutting process, avoids rebound after die-cutting, and prevents the adhesive from flowing toward the incision position to cause gluing, thereby preventing two adjacent finished labels from sticking to each other after die-cutting. Traditional labels must have a waste discharge area due to the problem of adhesion between two adjacent labels after die-cutting, resulting in a large amount of waste of substrate and glue. However, when the water-based polymer pressure-sensitive adhesive provided by the present invention is applied to labels, it is not easy for two adjacent finished labels to stick together during the die-cutting process, so that a waste discharge area does not need to be set when the labels are die-cut, achieving zero label waste.

[0109] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A water-based polymer pressure-sensitive adhesive, characterized in that: It is polymerized from the following raw materials in parts by weight: 4-6 parts of water-soluble polyester, 16-18 parts of C1-C4 alkyl ester of methacrylate, 16-18 parts of C4-C8 alkyl ester of acrylic acid, and (meth) urea acrylate CHR 1 CH-COOR 2 2-8 parts, 4-5 parts of cycloalkyl methacrylate, wherein R 1 is H or methyl, R 2 is a linear or cyclic ureido group containing 3 to 5 carbon atoms, and the cycloalkyl ester of methacrylic acid is C5-C 20 Cycloalkyl esters; The water-soluble polyester is obtained by polymerizing the following raw materials in parts by weight: 1-5 parts of sulfonate for polyester modification, hydroxyalkyl (meth) acrylic acid ester CHR 3 CH-COOR 4 OH 10-15 parts, terephthalic acid 60-80 parts, ethylene glycol 20-30 parts, of which R 3 is H or methyl, R 4 It is a straight or branched chain alkylene group containing 2 to 5 carbon atoms.

2. The water-based polymer pressure-sensitive adhesive according to claim 1, characterized in that: The ureido (meth)acrylate CHR 1 CH-COOR 2 It is ethylene urea ethoxy methacrylate.

3. The water-based polymer pressure-sensitive adhesive according to claim 1, characterized in that: The hydroxyalkyl (meth)acrylate CHR 3 CH-COOR 4 OH is 2-hydroxyethyl acrylate, 3-hydroxypropyl methacrylate, 2-hydroxypropyl acrylate or 4-hydroxybutyl acrylate.

4. The water-based polymer pressure-sensitive adhesive according to claim 1, characterized in that: The hydroxyalkyl (meth)acrylate CHR 3 CH-COOR 4 OH is 4-hydroxybutyl acrylate.

5. The water-based polymer pressure-sensitive adhesive according to claim 1, characterized in that: The sulfonate used for polyester modification is sodium bis(hydroxyethyl)isophthalate-5-sulfonate.

6. The water-based polymer pressure-sensitive adhesive according to claim 1, characterized in that: The cycloalkyl ester of methacrylic acid is a C5-C 10 Cycloalkyl esters.

7. The water-based polymer pressure-sensitive adhesive according to claim 1, characterized in that: The viscosity of the water-soluble polyester is 5000-10000 mPa·s.

8. The water-based polymer pressure-sensitive adhesive according to claim 1, characterized in that: The preparation method of the water-based polymer pressure-sensitive adhesive is as follows: (1) mixing a water-soluble polyester with a C1-C4 alkyl methacrylate, a C4-C8 alkyl acrylate, a ureido acrylate, a cycloalkyl methacrylate and a first portion of deionized water, and stirring and emulsifying to obtain a monomer pre-emulsion having a solid content of 30% to 50%; (2) 50-100 parts by weight of the second portion of deionized water is heated and then added to 10%-20% of the monomer pre-emulsion obtained in step (1) to carry out a free radical polymerization reaction, and then the remaining pre-emulsion is added dropwise to carry out a free radical polymerization reaction. The viscosity of the obtained product is 100-500 mPa·s.

9. The water-based polymer pressure-sensitive adhesive according to claim 1, characterized in that: The preparation method of the water-based polymer pressure-sensitive adhesive is: (1) mixing a water-soluble polyester with C1-C4 alkyl methacrylate, C4-C8 alkyl acrylate, ureido acrylate, cycloalkyl methacrylate, the first portion of deionized water, and a free radical initiator, and stirring and emulsifying to obtain a monomer pre-emulsion, wherein the weight of the initiator is 0.3% to 0.8% of the total weight of the water-soluble polyester, C1-C4 alkyl methacrylate, C4-C8 alkyl acrylate, ureido acrylate, and cycloalkyl methacrylate; (2) The second portion of deionized water is heated to 78-82° C., 10%-20% of the monomer pre-emulsion obtained in step (1) is added, and the reaction is continued for 15-25 minutes. The remaining monomer pre-emulsion is then added dropwise over a period of 2-5 hours. After the addition is completed, the mixture is kept at 80-85° C. for 1-2 hours. The mixture is cooled to below 45° C., the pH value is adjusted to 7-8, and finally a wetting agent and a defoaming agent are added. The mixture is stirred evenly and filtered to obtain a water-based polymer pressure-sensitive adhesive.

10. A label material comprising a water-based polymer pressure-sensitive adhesive according to claim 1, characterized in that: It includes a polyester-based surface material and a water-based polymer pressure-sensitive adhesive that are bonded to each other.