Emulsion-type modified polyacrylate pressure-sensitive adhesive containing sericin and preparation method thereof

Abstract

The present invention provides an emulsion-type modified polyacrylate pressure-sensitive adhesive containing sericin and a preparation method thereof. The pressure-sensitive adhesive comprises the following raw materials, measured in parts by mass: 180-240 parts of n-butyl acrylate; 0.5-1.6 parts of acrylic acid; 0.5-1.6 parts of methyl methacrylate; 0.5-2.3 parts of vinyl pyrrolidone; 0.1-0.7 parts of 2-hydroxyethyl acrylate; 6-8 parts of an emulsifier; 0.9-1.2 parts of sodium bicarbonate; 1.2-2 parts of ammonium persulfate; 0.18-0.24 parts of n-dodecyl mercaptan; 182-246 parts of water; and 1-6 parts of a sericin solution. The pressure-sensitive adhesive prepared by the present invention improves the long-lasting adhesive properties of the emulsion-type polyacrylate pressure-sensitive adhesive while maintaining good peel strength and initial tack.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials and relates to an emulsion-type modified polyacrylate pressure-sensitive adhesive containing sericin and a preparation method thereof. Background Art

[0002] Pressure-sensitive adhesives (PSA) are pressure-sensitive adhesives widely used in production and daily life. Their performance indicators primarily include initial tack, sustained tack, and peel strength. Initial tack refers to the adhesive's ability to adhere to a surface under pressure upon initial contact, indicating the adhesive's wetting properties. Sustained tack is the adhesion developed after the adhesive completely wets the surface, determined by the adhesive's cohesive strength. Peel strength indicates the strength of the bond between the adhesive and the surface.

[0003] Emulsion-type polyacrylate pressure-sensitive adhesive is the most widely used pressure-sensitive adhesive product, with advantages such as low production cost and low environmental pollution. Emulsion-type polyacrylate pressure-sensitive adhesive has good peel strength, but its persistent adhesion is weaker than that of solvent-based pressure-sensitive adhesive. In order to improve the performance of emulsion-type polyacrylate pressure-sensitive adhesive, various modification technologies have developed rapidly (Li Qinglian. Analysis of patents of emulsion-type acrylic pressure-sensitive adhesive in China [J]. China Adhesives, 2020, 29(7):8.). Among them, improving the persistent adhesion of pressure-sensitive adhesive is the focus of research. Chinese patent ZL201811537246.7 (Removable emulsion-type acrylic pressure-sensitive adhesive containing silicone crosslinker and its preparation method) mixes polyacrylate emulsion with silicone crosslinker. The crosslinking effect of silicone significantly improves the persistent adhesion of pressure-sensitive adhesive, but the initial adhesion and peel strength of pressure-sensitive adhesive show a significant decrease. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention provides an emulsion-type modified polyacrylate pressure-sensitive adhesive containing sericin and a preparation method thereof, to achieve the following invention objectives:

[0005] Improve the tackiness of emulsion-based polyacrylate pressure-sensitive adhesives while maintaining good initial tack and peel strength.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] An emulsion-type modified polyacrylate pressure-sensitive adhesive containing sericin, the pressure-sensitive adhesive comprising the following raw material components in parts by mass:

[0008] n-Butyl acrylate: 180-240 parts;

[0009] Acrylic acid: 0.5-1.6 parts;

[0010] Methyl methacrylate: 0.5-1.6 parts;

[0011] Vinyl pyrrolidone: 0.5-2.3 parts;

[0012] 2-Hydroxyethyl acrylate: 0.1-0.7 parts;

[0013] Emulsifier: 6-8 parts;

[0014] NaHCO3: 0.9-1.2 parts;

[0015] Ammonium persulfate: 1.2-2 parts;

[0016] n-Dodecanethiol: 0.18-0.24 parts;

[0017] Water: 182-246 parts;

[0018] Sericin solution: 1 to 6 parts.

[0019] The mass fraction of the sericin solution is 24-26%; the weight average molecular weight of the sericin is 91-213 kDa.

[0020] The emulsifier is one of sodium dodecyl diphenyl ether disulfonate, octylphenol polyoxyethylene ether-10, and ethoxylated alkylphenol ammonium sulfate.

[0021] A method for preparing an emulsion-type modified polyacrylate pressure-sensitive adhesive containing sericin comprises the following steps: preparing a seed emulsion, preparing a modified polyacrylate emulsion, and adding a sericin solution.

[0022] The method for preparing the seed emulsion comprises adding 18-24 parts by mass of n-butyl acrylate, 0.1-0.4 parts by mass of acrylic acid, 0.1-0.4 parts by mass of methyl methacrylate, 0.5-2.3 parts by mass of vinyl pyrrolidone, 0.1-0.7 parts by mass of 2-hydroxyethyl acrylate, 4.5-5.2 parts by mass of an emulsifier, 145-197 parts by mass of water, and 0.9-1.2 parts by mass of sodium bicarbonate into a reactor, stirring at 230-280 rpm for 18-22 minutes until uniformly stirred; raising the temperature to 70-80°C, adding 0.2-0.7 parts by mass of ammonium persulfate, continuing stirring at 230-280 rpm for 28-32 minutes, and stirring uniformly to prepare the seed emulsion.

[0023] The method for preparing the modified polyacrylate emulsion comprises adding 162-216 parts by mass of n-butyl acrylate, 0.4-1.2 parts by mass of acrylic acid, and 0.4-1.2 parts by mass of methyl methacrylate to a seed emulsion, then adding 2.5-2.8 parts by mass of an emulsifier, 37-49 parts by mass of water, and 1-1.3 parts by mass of ammonium persulfate, and continuing to stir and react at 70-80°C at a speed of 180-230 rpm for 2.8-3.2 hours; and finally adding 0.18-0.24 parts by mass of n-dodecyl mercaptan, and continuing to stir at 180-230 rpm for 28-32 minutes to prepare the modified polyacrylate emulsion.

[0024] The method of adding the sericin solution is to add 1-6 parts by mass of the sericin solution to the modified polyacrylate emulsion, stir at 180-230 rpm for 0.9-1.1 hours at room temperature, and mix evenly to prepare an emulsion-type polyacrylate pressure-sensitive adhesive containing sericin.

[0025] The present invention utilizes a copolymerization method to prepare a modified polyacrylate containing vinyl pyrrolidone. Sericin is then added to the emulsion. Pyrrolidone contains polar groups, while water-soluble sericin contains hydroxyl and amino groups. In the emulsion, the modified polyacrylate and sericin form hydrogen bonds, allowing the sericin chains to evenly disperse around and coat the modified polyacrylate. This creates a hydrogen-bonded network in the emulsion, significantly enhancing the pressure-sensitive adhesive's tack while maintaining essentially unchanged peel strength.

[0026] Compared with the prior art, the present invention achieves the following beneficial effects:

[0027] (1) The pressure-sensitive adhesive prepared by the present invention improves the sustained adhesion of the emulsion-type polyacrylate pressure-sensitive adhesive while maintaining good peel strength and initial tack. The pressure-sensitive adhesive prepared by the present invention has a sustained adhesion of 22.3 to 53.6 hours, a 180° peel strength of 13.8 to 19.5 N / 25 mm, and an initial tack of 23 to 27 (#) balls.

[0028] (2) The present invention is used for the emulsion type polyacrylate pressure-sensitive adhesive containing sericin. The production method is simple and can be produced using conventional pressure-sensitive adhesive production equipment. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0030] Example 1: An emulsion-type modified polyacrylate pressure-sensitive adhesive containing sericin

[0031] The pressure-sensitive adhesive comprises the following raw material components in parts by mass:

[0032] n-Butyl acrylate: 200 parts;

[0033] Acrylic acid: 1 part;

[0034] Methyl methacrylate: 1 part;

[0035] Vinyl pyrrolidone: 0.8 parts;

[0036] 2-Hydroxyethyl acrylate: 0.2 parts;

[0037] Emulsifier: 7 parts;

[0038] NaHCO3: 1 part;

[0039] Ammonium persulfate: 1.6 parts;

[0040] n-Dodecanethiol: 0.2 parts;

[0041] Water: 204 parts;

[0042] Sericin solution: 2 parts.

[0043] The preparation method of the pressure-sensitive adhesive is as follows:

[0044] (1) Preparation of seed emulsion

[0045] Under room temperature, 20 parts by mass of n-butyl acrylate, 0.2 parts by mass of acrylic acid, 0.2 parts by mass of methyl methacrylate, 0.8 parts by mass of vinyl pyrrolidone, 0.2 parts by mass of 2-hydroxyethyl acrylate, 4.5 parts by mass of sodium dodecyl diphenyl ether disulfonate, 160 parts by mass of water, and 1 part by mass of sodium bicarbonate (buffer) were placed in a reactor and stirred at 250 rpm for 20 minutes until uniform. The temperature was raised to 75° C., 0.3 parts by mass of ammonium persulfate was added, and stirring was continued at 250 rpm for 30 minutes until uniform to obtain a seed emulsion.

[0046] (2) Preparation of modified polyacrylate emulsion

[0047] 180 parts by mass of n-butyl acrylate, 0.8 parts by mass of acrylic acid, and 0.8 parts by mass of methyl methacrylate were added to the seed emulsion prepared in step (1), followed by 2.5 parts by mass of sodium dodecyl diphenyl ether disulfonate, 44 parts by mass of water, and 1.3 parts by mass of ammonium persulfate. The mixture was stirred at 75°C and 200 rpm for 3 hours. Finally, 0.2 parts by mass of n-dodecyl mercaptan was added, and the mixture was stirred at 200 rpm for 30 minutes to prepare a modified polyacrylate emulsion.

[0048] (3) Add sericin solution

[0049] 2 parts by mass of the sericin solution were added to the modified polyacrylate emulsion prepared in step (2), and the mixture was stirred at 200 rpm at room temperature for 1 hour to obtain a sericin-containing emulsion-type polyacrylate pressure-sensitive adhesive.

[0050] The mass fraction of the sericin solution is 25%;

[0051] The weight average molecular weight of the sericin is 173 kDa.

[0052] Application performance testing:

[0053] Use HG / T 5054-2016 "Water-based acrylic pressure-sensitive adhesives for adhesive products" and prepare the test specimens for packaging applications according to 7.4.2.1. Maintain an adhesive layer thickness of 22μm ± 2μm.

[0054] Using GB / T 2792 "Test method for peel strength of adhesive tapes" and method 1, the 180° peel strength was measured to be 19.5 N / 25 mm.

[0055] Adopting GB / T 4852 "Test method for initial tack of pressure-sensitive adhesive tapes (rolling ball method)", according to method A, the tilt angle is 30 degrees, and the initial tack is measured to be 23 (#) balls.

[0056] Adopting GB / T4851 "Test method for adhesive tape holding power", according to method A, the holding power is 22.3h.

[0057] Example 2: An emulsion-type modified polyacrylate pressure-sensitive adhesive containing sericin

[0058] The pressure-sensitive adhesive comprises the following raw material components in parts by mass:

[0059] n-Butyl acrylate: 180 parts;

[0060] Acrylic acid: 0.5 parts;

[0061] Methyl methacrylate: 0.5 parts;

[0062] Vinyl pyrrolidone: 0.5 parts;

[0063] 2-Hydroxyethyl acrylate: 0.1 part;

[0064] Emulsifier: 7.2 parts;

[0065] NaHCO3: 0.9 parts;

[0066] Ammonium persulfate: 1.2 parts;

[0067] n-Dodecanethiol: 0.18 parts;

[0068] Water: 182 parts;

[0069] Sericin solution: 1 part.

[0070] The preparation method of the pressure-sensitive adhesive is as follows:

[0071] (1) Preparation of seed emulsion

[0072] Under room temperature, 18 parts by mass of n-butyl acrylate, 0.1 parts by mass of acrylic acid, 0.1 parts by mass of methyl methacrylate, 0.5 parts by mass of vinyl pyrrolidone, 0.1 parts by mass of 2-hydroxyethyl acrylate, 4.6 parts by mass of sodium dodecyl diphenyl ether disulfonate, 145 parts by mass of water, and 0.9 parts by mass of sodium bicarbonate (buffer) were placed in a reactor and stirred at 230 rpm for 20 minutes until uniform. The temperature was raised to 70° C., 0.2 parts by mass of ammonium persulfate was added, and stirring was continued at 230 rpm for 30 minutes until uniform to obtain a seed emulsion.

[0073] (2) Preparation of modified polyacrylate emulsion

[0074] 162 parts by mass of n-butyl acrylate, 0.4 parts by mass of acrylic acid, and 0.4 parts by mass of methyl methacrylate were added to the seed emulsion prepared in step (1), followed by 2.6 parts by mass of sodium dodecyl diphenyl ether disulfonate, 37 parts by mass of water, and 1 part by mass of ammonium persulfate. The mixture was stirred at 70°C and 180 rpm for 3 hours. Finally, 0.18 parts by mass of n-dodecyl mercaptan was added, and the mixture was stirred at 180 rpm for 30 minutes to prepare a modified polyacrylate emulsion.

[0075] (3) Add sericin solution

[0076] 1 part by mass of the sericin solution was added to the modified polyacrylate emulsion obtained in step (2), and the mixture was stirred at 180 rpm for 1 hour at room temperature to obtain a sericin-containing emulsion-type polyacrylate pressure-sensitive adhesive.

[0077] The mass fraction of the sericin solution is 25%;

[0078] The weight average molecular weight of the sericin is 91 kDa.

[0079] Application performance testing:

[0080] Use HG / T 5054-2016 "Water-based acrylic pressure-sensitive adhesives for adhesive products" and prepare the test specimens for packaging applications according to 7.4.2.1. Maintain an adhesive layer thickness of 22μm ± 2μm.

[0081] Using GB / T 2792 "Test method for peel strength of adhesive tapes" and method 1, the 180° peel strength was measured to be 18.6 N / 25 mm.

[0082] Adopt GB / T 4852 "Test method for initial tack of pressure-sensitive adhesive tapes (rolling ball method)", according to method A, the tilt angle is 30 degrees, and the initial tack is measured to be 25 (#) balls.

[0083] Adopting GB / T4851 "Test method for adhesive tape holding power", according to method A, the holding power is 28.9h.

[0084] Example 3: An emulsion-type modified polyacrylate pressure-sensitive adhesive containing sericin

[0085] The pressure-sensitive adhesive comprises the following raw material components in parts by mass:

[0086] n-Butyl acrylate: 190 parts;

[0087] Acrylic acid: 0.7 parts;

[0088] Methyl methacrylate: 0.8 parts;

[0089] Vinyl pyrrolidone: 1.1 parts;

[0090] 2-Hydroxyethyl acrylate: 0.4 parts;

[0091] Emulsifier: 7.3 parts;

[0092] NaHCO3: 1 part;

[0093] Ammonium persulfate: 1.4 parts;

[0094] n-Dodecanethiol: 0.19 parts;

[0095] Water: 193 parts;

[0096] Sericin solution: 2 parts.

[0097] The preparation method of the pressure-sensitive adhesive is as follows:

[0098] (1) Preparation of seed emulsion

[0099] Under room temperature, 19 parts by mass of n-butyl acrylate, 0.2 parts by mass of acrylic acid, 0.3 parts by mass of methyl methacrylate, 1.1 parts by mass of vinyl pyrrolidone, 0.4 parts by mass of 2-hydroxyethyl acrylate, 4.7 parts by mass of octylphenol polyoxyethylene ether-10, 154 parts by mass of water, and 1 part by mass of sodium bicarbonate (buffer) were placed in a reactor and stirred at 240 rpm for 20 minutes until uniform. The temperature was raised to 70° C., 0.3 parts by mass of ammonium persulfate was added, and stirring was continued at 240 rpm for 30 minutes until uniform to obtain a seed emulsion.

[0100] (2) Preparation of modified polyacrylate emulsion

[0101] 171 parts by mass of n-butyl acrylate, 0.5 parts by mass of acrylic acid, and 0.5 parts by mass of methyl methacrylate were added to the seed emulsion prepared in step (1), followed by 2.6 parts by mass of octylphenol polyoxyethylene ether-10, 39 parts by mass of water, and 1.1 parts by mass of ammonium persulfate. The mixture was stirred at 70°C and 190 rpm for 3 hours. Finally, 0.19 parts by mass of n-dodecyl mercaptan was added, and the mixture was stirred at 190 rpm for 30 minutes to prepare a modified polyacrylate emulsion.

[0102] (3) Add sericin solution

[0103] 2 parts by mass of the sericin solution were added to the modified polyacrylate emulsion obtained in step (2), and the mixture was stirred at 190 rpm for 1 hour at room temperature to obtain a sericin-containing emulsion polyacrylate pressure-sensitive adhesive.

[0104] The mass fraction of the sericin solution is 25%;

[0105] The weight average molecular weight of the sericin is 134 kDa.

[0106] Application performance testing:

[0107] Use HG / T 5054-2016 "Water-based acrylic pressure-sensitive adhesives for adhesive products" and prepare the test specimens for packaging applications according to 7.4.2.1. Maintain an adhesive layer thickness of 22μm ± 2μm.

[0108] Using GB / T 2792 "Test method for peel strength of adhesive tapes" and method 1, the 180° peel strength was measured to be 17.4 N / 25 mm.

[0109] Adopting GB / T 4852 "Test method for initial tack of pressure-sensitive adhesive tapes (rolling ball method)", according to method A, the tilt angle is 30 degrees, and the initial tack is measured to be 27 (#) balls.

[0110] Adopting GB / T4851 "Test method for adhesive tape holding power", according to method A, the holding power is 31.5h.

[0111] Example 4: An emulsion-type modified polyacrylate pressure-sensitive adhesive containing sericin

[0112] The pressure-sensitive adhesive comprises the following raw material components in parts by mass:

[0113] n-Butyl acrylate: 210 parts;

[0114] Acrylic acid: 1.2 parts;

[0115] Methyl methacrylate: 0.8 parts;

[0116] Vinyl pyrrolidone: 1.3 parts;

[0117] 2-Hydroxyethyl acrylate: 0.7 parts;

[0118] Emulsifier: 7.5 parts;

[0119] NaHCO3: 1 part;

[0120] Ammonium persulfate: 1.5 parts;

[0121] n-Dodecanethiol: 0.21 parts;

[0122] Water: 214 parts;

[0123] Sericin solution: 3 parts.

[0124] The preparation method of the pressure-sensitive adhesive is as follows:

[0125] (1) Preparation of seed emulsion

[0126] Under room temperature, 21 parts by mass of n-butyl acrylate, 0.3 parts by mass of acrylic acid, 0.2 parts by mass of methyl methacrylate, 1.3 parts by mass of vinyl pyrrolidone, 0.7 parts by mass of 2-hydroxyethyl acrylate, 4.8 parts by mass of octylphenol polyoxyethylene ether-10, 171 parts by mass of water, and 1 part by mass of sodium bicarbonate (buffer) were placed in a reactor and stirred at 260 rpm for 20 minutes until uniform. The temperature was raised to 75° C., 0.5 parts by mass of ammonium persulfate was added, and stirring was continued at 260 rpm for 30 minutes until uniform to obtain a seed emulsion.

[0127] (2) Preparation of modified polyacrylate emulsion

[0128] 189 parts by mass of n-butyl acrylate, 0.9 parts by mass of acrylic acid, and 0.6 parts by mass of methyl methacrylate were added to the seed emulsion prepared in step (1), followed by 2.7 parts by mass of octylphenol polyoxyethylene ether-10, 43 parts by mass of water, and 1.0 parts by mass of ammonium persulfate. The mixture was stirred at 75°C and 210 rpm for 3 hours. Finally, 0.21 parts by mass of n-dodecyl mercaptan was added, and the mixture was stirred at 210 rpm for 30 minutes to prepare a modified polyacrylate emulsion.

[0129] (3) Add sericin solution

[0130] 3 parts by mass of the sericin solution were added to the modified polyacrylate emulsion obtained in step (2), and stirred at 210 rpm for 1 hour at room temperature to mix evenly, thereby obtaining an emulsion-type polyacrylate pressure-sensitive adhesive containing sericin.

[0131] The mass fraction of the sericin solution is 25%;

[0132] The weight average molecular weight of the sericin is 187 kDa.

[0133] Application performance testing:

[0134] Use HG / T 5054-2016 "Water-based acrylic pressure-sensitive adhesives for adhesive products" and prepare the test specimens for packaging applications according to 7.4.2.1. Maintain an adhesive layer thickness of 22μm ± 2μm.

[0135] Using GB / T 2792 "Test method for peel strength of adhesive tapes" and method 1, the 180° peel strength was measured to be 17.8 N / 25mm.

[0136] Adopt GB / T 4852 "Test method for initial tack of pressure-sensitive adhesive tapes (rolling ball method)", according to method A, the tilt angle is 30 degrees, and the initial tack is measured to be 25 (#) balls.

[0137] Adopting GB / T4851 "Test method for adhesive tape holding power", according to method A, the holding power is 43.2h.

[0138] Example 5: An emulsion-type modified polyacrylate pressure-sensitive adhesive containing sericin

[0139] The pressure-sensitive adhesive comprises the following raw material components in parts by mass:

[0140] n-Butyl acrylate: 220 parts;

[0141] Acrylic acid: 0.8 parts;

[0142] Methyl methacrylate: 1.2 parts;

[0143] Vinyl pyrrolidone: 1.5 parts;

[0144] 2-Hydroxyethyl acrylate: 0.7 parts;

[0145] Emulsifier: 7.7 parts;

[0146] NaHCO3: 1.1 parts;

[0147] Ammonium persulfate: 1.6 parts;

[0148] n-Dodecanethiol: 0.22 parts;

[0149] Water: 224.2 parts;

[0150] Sericin solution: 4 parts.

[0151] The preparation method of the pressure-sensitive adhesive is as follows:

[0152] (1) Preparation of seed emulsion

[0153] Under room temperature, 22 parts by mass of n-butyl acrylate, 0.2 parts by mass of acrylic acid, 0.3 parts by mass of methyl methacrylate, 1.5 parts by mass of vinyl pyrrolidone, 0.7 parts by mass of 2-hydroxyethyl acrylate, 4.9 parts by mass of octylphenol polyoxyethylene ether-10, 179.2 parts by mass of water, and 1.1 parts by mass of sodium bicarbonate (buffer) were placed in a reactor and stirred at 260 rpm for 20 minutes until uniform. The temperature was raised to 80° C., 0.5 parts by mass of ammonium persulfate was added, and stirring was continued at 260 rpm for 30 minutes until uniform to obtain a seed emulsion.

[0154] (2) Preparation of modified polyacrylate emulsion

[0155] 198 parts by mass of n-butyl acrylate, 0.6 parts by mass of acrylic acid, and 0.9 parts by mass of methyl methacrylate were added to the seed emulsion prepared in step (1), followed by 2.8 parts by mass of octylphenol polyoxyethylene ether-10, 45 parts by mass of water, and 1.1 parts by mass of ammonium persulfate. The mixture was stirred at 80°C and 210 rpm for 3 hours. Finally, 0.22 parts by mass of n-dodecyl mercaptan was added, and the mixture was stirred at 210 rpm for 30 minutes to prepare a modified polyacrylate emulsion.

[0156] (3) Add sericin solution

[0157] 4 parts by mass of the sericin solution were added to the modified polyacrylate emulsion obtained in step (2), and stirred at 210 rpm for 1 hour at room temperature to mix evenly, thereby obtaining an emulsion-type polyacrylate pressure-sensitive adhesive containing sericin.

[0158] The mass fraction of the sericin solution is 25%;

[0159] The weight average molecular weight of the sericin is 192 kDa.

[0160] Application performance testing:

[0161] Use HG / T 5054-2016 "Water-based acrylic pressure-sensitive adhesives for adhesive products" and prepare the test specimens for packaging applications according to 7.4.2.1. Maintain an adhesive layer thickness of 22μm ± 2μm.

[0162] Using GB / T 2792 "Test method for peel strength of adhesive tapes" and method 1, the 180° peel strength was measured to be 16.7 N / 25mm.

[0163] Adopting GB / T 4852 "Test method for initial tack of pressure-sensitive adhesive tapes (rolling ball method)", according to method A, the tilt angle is 30 degrees, and the initial tack is measured to be 26 (#) balls.

[0164] Adopting GB / T4851 "Test method for adhesive tape holding power", according to method A, the holding power is 47.9h.

[0165] Example 6: An emulsion-type modified polyacrylate pressure-sensitive adhesive containing sericin

[0166] The pressure-sensitive adhesive comprises the following raw material components in parts by mass:

[0167] n-Butyl acrylate: 230 parts;

[0168] Acrylic acid: 1.6 parts;

[0169] Methyl methacrylate: 1.4 parts;

[0170] Vinyl pyrrolidone: 2.1 parts;

[0171] 2-Hydroxyethyl acrylate: 0.4 parts;

[0172] Emulsifier: 7.8 parts;

[0173] NaHCO3: 1.12 parts;

[0174] Ammonium persulfate: 1.8 parts;

[0175] n-Dodecanethiol: 0.23 parts;

[0176] Water: 235.5 parts;

[0177] Sericin solution: 5 parts.

[0178] The preparation method of the pressure-sensitive adhesive is as follows:

[0179] (1) Preparation of seed emulsion

[0180] Under room temperature, 23 parts by mass of n-butyl acrylate, 0.4 parts by mass of acrylic acid, 0.3 parts by mass of methyl methacrylate, 2.1 parts by mass of vinyl pyrrolidone, 0.4 parts by mass of 2-hydroxyethyl acrylate, 5.0 parts by mass of ethoxylated alkylphenol ammonium sulfate, 188.5 parts by mass of water, and 1.12 parts by mass of sodium bicarbonate (buffer) were placed in a reactor and stirred at 270 rpm for 20 minutes until uniform. The temperature was raised to 80° C., 0.6 parts by mass of ammonium persulfate was added, and stirring was continued at 270 rpm for 30 minutes until uniform to prepare a seed emulsion.

[0181] (2) Preparation of modified polyacrylate emulsion

[0182] 207 parts by mass of n-butyl acrylate, 1.2 parts by mass of acrylic acid, and 1.1 parts by mass of methyl methacrylate were added to the seed emulsion prepared in step (1), followed by 2.8 parts by mass of ethoxylated alkylphenol ammonium sulfate, 47 parts by mass of water, and 1.2 parts by mass of ammonium persulfate. The mixture was stirred at 80°C and 220 rpm for 3 hours. Finally, 0.23 parts by mass of n-dodecyl mercaptan was added, and stirring was continued at 220 rpm for 30 minutes to prepare a modified polyacrylate emulsion.

[0183] (3) Add sericin solution

[0184] 5 parts by mass of the sericin solution was added to the modified polyacrylate emulsion obtained in step (2), and the mixture was stirred at 220 rpm for 1 hour at room temperature to obtain a sericin-containing emulsion-type polyacrylate pressure-sensitive adhesive.

[0185] The mass fraction of the sericin solution is 25%;

[0186] The weight average molecular weight of the sericin is 203 kDa.

[0187] Application performance testing:

[0188] Use HG / T 5054-2016 "Water-based acrylic pressure-sensitive adhesives for adhesive products" and prepare the test specimens for packaging applications according to 7.4.2.1. Maintain an adhesive layer thickness of 22μm ± 2μm.

[0189] Using GB / T 2792 "Test method for peel strength of adhesive tapes" and method 1, the 180° peel strength was measured to be 15.4 N / 25 mm.

[0190] Adopt GB / T 4852 "Test method for initial tack of pressure-sensitive adhesive tapes (rolling ball method)", according to method A, the tilt angle is 30 degrees, and the initial tack is measured to be 25 (#) balls.

[0191] Adopting GB / T4851 "Test method for adhesive tape holding power", according to method A, the holding power is 51.8h.

[0192] Example 7: An emulsion-type modified polyacrylate pressure-sensitive adhesive containing sericin

[0193] The pressure-sensitive adhesive comprises the following raw material components in parts by mass:

[0194] n-Butyl acrylate: 240 parts;

[0195] Acrylic acid: 1.4 parts;

[0196] Methyl methacrylate: 1.6 parts;

[0197] Vinyl pyrrolidone: 2.3 parts;

[0198] 2-Hydroxyethyl acrylate: 0.7 parts;

[0199] Emulsifier: 8 parts;

[0200] NaHCO3: 1.2 parts;

[0201] Ammonium persulfate: 2.0 parts;

[0202] n-Dodecanethiol: 0.24 parts;

[0203] Water: 246 parts;

[0204] Sericin solution: 6 parts.

[0205] The preparation method of the pressure-sensitive adhesive is as follows:

[0206] (1) Preparation of seed emulsion

[0207] Under room temperature, 24 parts by mass of n-butyl acrylate, 0.3 parts by mass of acrylic acid, 0.4 parts by mass of methyl methacrylate, 2.3 parts by mass of vinyl pyrrolidone, 0.7 parts by mass of 2-hydroxyethyl acrylate, 5.2 parts by mass of ethoxylated alkylphenol ammonium sulfate, 197 parts by mass of water, and 1.2 parts by mass of sodium bicarbonate (buffer) were placed in a reactor and stirred at 280 rpm for 20 minutes until uniform. The temperature was raised to 80° C., 0.7 parts by mass of ammonium persulfate was added, and stirring was continued at 280 rpm for 30 minutes until uniform to prepare a seed emulsion.

[0208] (2) Preparation of modified polyacrylate emulsion

[0209] 216 parts by mass of n-butyl acrylate, 1.1 parts by mass of acrylic acid, and 1.2 parts by mass of methyl methacrylate were added to the seed emulsion prepared in step (1), followed by 2.8 parts by mass of ethoxylated alkylphenol ammonium sulfate, 49 parts by mass of water, and 1.3 parts by mass of ammonium persulfate. The mixture was stirred at 80°C and 230 rpm for 3 hours. Finally, 0.24 parts by mass of n-dodecyl mercaptan was added, and stirring was continued at 230 rpm for 30 minutes to prepare a modified polyacrylate emulsion.

[0210] (3) Add sericin solution

[0211] 6 parts by mass of the sericin solution were added to the modified polyacrylate emulsion obtained in step (2), and stirred at 230 rpm for 1 hour at room temperature to mix evenly, thereby obtaining an emulsion-type polyacrylate pressure-sensitive adhesive containing sericin.

[0212] The mass fraction of the sericin solution is 25%;

[0213] The weight average molecular weight of the sericin is 213 kDa.

[0214] Application performance testing:

[0215] Use HG / T 5054-2016 "Water-based acrylic pressure-sensitive adhesives for adhesive products" and prepare the test specimens for packaging applications according to 7.4.2.1. Maintain an adhesive layer thickness of 22μm ± 2μm.

[0216] Using GB / T 2792 "Test method for peel strength of adhesive tapes" and method 1, the 180° peel strength was measured to be 13.8 N / 25 mm.

[0217] Adopt GB / T 4852 "Test method for initial tack of pressure-sensitive adhesive tapes (rolling ball method)" according to method A, the tilt angle is 30 degrees, and the initial tack is measured to be 24 (#) balls.

[0218] Adopting GB / T4851 "Test method for adhesive tape holding power", according to method A, the holding power is 53.6h.

[0219] Comparative Example 1

[0220] Based on Example 1, the addition of vinyl pyrrolidone and sericin solution was omitted, and the rest was the same as Example 1.

[0221] The pressure-sensitive agent prepared in Example 1 was tested for its application performance:

[0222] Use HG / T 5054-2016 "Water-based acrylic pressure-sensitive adhesives for adhesive products" and prepare the test specimens for packaging applications according to 7.4.2.1. Maintain an adhesive layer thickness of 22μm ± 2μm.

[0223] Using GB / T 2792 "Test method for peel strength of adhesive tapes" and method 1, the 180° peel strength was measured to be 20.3 N / 25 mm.

[0224] Adopt GB / T 4852 "Test method for initial tack of pressure-sensitive adhesive tapes (rolling ball method)", according to method A, the tilt angle is 30 degrees, and the initial tack is measured to be 20 (#) balls.

[0225] Adopting GB / T4851 "Test method for adhesive tape holding power", according to method A, the holding power is 2.6h.

[0226] It can be seen that the pressure-sensitive adhesive prepared in Comparative Example 1 has a tack retention of only 2.6 h, which is significantly lower than that of Example 1 (22.3 h).

[0227] Comparative Example 2

[0228] On the basis of Example 1, the addition of the sericin solution was omitted, and the rest was the same as Example 1.

[0229] The pressure-sensitive agent prepared in Example 2 was tested for its application performance:

[0230] Use HG / T 5054-2016 "Water-based acrylic pressure-sensitive adhesives for adhesive products" and prepare the test specimens for packaging applications according to 7.4.2.1. Maintain an adhesive layer thickness of 22μm ± 2μm.

[0231] Using GB / T 2792 "Test method for peel strength of adhesive tapes" and method 1, the 180° peel strength was measured to be 17.7 N / 25 mm.

[0232] Adopting GB / T 4852 "Test method for initial tack of pressure-sensitive adhesive tapes (rolling ball method)", according to method A, the tilt angle is 30 degrees, and the initial tack is measured to be 22 (#) balls.

[0233] Adopting GB / T4851 "Test method for adhesive tape holding power", according to method A, the holding power is 5.3h.

[0234] Comparative Example 3

[0235] On the basis of Example 1, the addition of vinyl pyrrolidone was omitted, and the rest was the same as Example 1.

[0236] The pressure-sensitive agent prepared in Example 3 was tested for its application performance:

[0237] Use HG / T 5054-2016 "Water-based acrylic pressure-sensitive adhesives for adhesive products" and prepare the test specimens for packaging applications according to 7.4.2.1. Maintain an adhesive layer thickness of 22μm ± 2μm.

[0238] Using GB / T 2792 "Test method for peel strength of adhesive tapes" and method 1, the 180° peel strength was measured to be 21.0 N / 25 mm.

[0239] Adopting GB / T 4852 "Test method for initial tack of pressure-sensitive adhesive tapes (rolling ball method)", according to method A, the tilt angle is 30 degrees, and the initial tack is measured to be 22 (#) balls.

[0240] Adopting GB / T4851 "Test method for adhesive tape holding power", according to method A, the holding power is 3.1h.

[0241] The pressure-sensitive adhesive raw material of Comparative Example 2 contains vinyl pyrrolidone, but no sericin solution is added; the pressure-sensitive adhesive raw material of Comparative Example 3 contains sericin solution, but no vinyl pyrrolidone is added. The pressure-sensitive adhesive raw material of Example 1 contains both vinyl pyrrolidone and sericin solution. A comparison of the performance indicators of the finally prepared pressure-sensitive adhesives shows that the pressure-sensitive adhesives prepared in Comparative Examples 2 and 3 have significantly lower tack than Example 1, while their initial tack and peel strength are at comparable levels.

Claims

1. An emulsion-type modified polyacrylate pressure-sensitive adhesive containing sericin, characterized in that: The pressure-sensitive adhesive comprises the following raw material components in parts by mass: n-Butyl acrylate: 180-240 parts; Acrylic acid: 0.5-1.6 parts; Methyl methacrylate: 0.5-1.6 parts; Vinyl pyrrolidone: 0.5-2.3 parts; 2-Hydroxyethyl acrylate: 0.1-0.7 parts; Emulsifier: 6-8 parts; NaHCO3: 0.9-1.2 parts; Ammonium persulfate: 1.2-2 parts; n-Dodecanethiol: 0.18-0.24 parts; Water: 182-246 parts; Sericin solution: 1 to 6 parts.

2. The emulsion-type modified polyacrylate pressure-sensitive adhesive containing sericin according to claim 1, characterized in that: The mass fraction of the sericin solution is 24-26%; the weight average molecular weight of the sericin is 91-213 kDa.

3. The emulsion-type modified polyacrylate pressure-sensitive adhesive containing sericin according to claim 1, characterized in that: The emulsifier is one of sodium dodecyl diphenyl ether disulfonate, octylphenol polyoxyethylene ether-10, and ethoxylated alkylphenol ammonium sulfate.

4. The method for preparing the emulsion-type modified polyacrylate pressure-sensitive adhesive containing sericin according to any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: preparing a seed emulsion, preparing a modified polyacrylate emulsion, and adding a sericin solution; The method for preparing the seed emulsion comprises adding 18-24 parts by mass of n-butyl acrylate, 0.1-0.4 parts by mass of acrylic acid, 0.1-0.4 parts by mass of methyl methacrylate, 0.5-2.3 parts by mass of vinyl pyrrolidone, 0.1-0.7 parts by mass of 2-hydroxyethyl acrylate, 4.5-5.2 parts by mass of an emulsifier, 145-197 parts by mass of water, and 0.9-1.2 parts by mass of sodium bicarbonate into a reactor and stirring uniformly; raising the temperature to 70-80° C., adding 0.2-0.7 parts by mass of ammonium persulfate, and continuing stirring at 230-280 rpm for 28-32 minutes, and stirring uniformly to prepare the seed emulsion; The method for preparing the modified polyacrylate emulsion comprises adding 162-216 parts by mass of n-butyl acrylate, 0.4-1.2 parts by mass of acrylic acid, and 0.4-1.2 parts by mass of methyl methacrylate to a seed emulsion, then adding 2.5-2.8 parts by mass of an emulsifier, 37-49 parts by mass of water, and 1-1.3 parts by mass of ammonium persulfate, and continuing to stir and react at 70-80°C at a speed of 180-230 rpm for 2.8-3.2 hours; and finally adding 0.18-0.24 parts by mass of n-dodecyl mercaptan, and continuing to stir at 180-230 rpm for 28-32 minutes to prepare the modified polyacrylate emulsion.

5. The preparation method according to claim 4, characterized in that: The method of adding the sericin solution is to add 1-6 parts by mass of the sericin solution to the modified polyacrylate emulsion, stir at 180-230 rpm for 0.9-1.1 hours at room temperature, and mix evenly to prepare an emulsion-type polyacrylate pressure-sensitive adhesive containing sericin.