Water-based adhesive for cigarettes and preparation process of water-based adhesive

Abstract

The invention discloses a water-based adhesive for cigarettes and a preparation process thereof, and belongs to the technical field of preparation of special adhesives, the water-based adhesive for cigarettes comprises the following components: an acrylic resin emulsion, an ethylene-vinyl acetate copolymer emulsion, a starch-based component, an auxiliary agent and deionized water; wherein the starch-based component is prepared by taking starch as a raw material, performing vacuum heat treatment, dehydration and pre-gelatinization, then mixing with polyvinyl alcohol, and performing esterification reaction with acrylic acid and abietic acid under the alkaline condition of sodium hydroxide; the water-based adhesive for cigarettes, which is high in bonding strength, good in initial adhesion performance, fast to dry and stable in emulsion, is prepared by modifying the composite components, and the acrylate emulsion and the modified starch component are compounded on the basis of the existing EVA emulsion, so that the crosslinking and curing speed is increased while the emulsification is promoted.

Description

Technical Field

[0001] The invention relates to the technical field of special adhesive preparation, and in particular to a water-based adhesive for cigarettes and a preparation process thereof. Background Art

[0002] Water-based adhesive for cigarettes is an adhesive used in the tobacco industry. It is one of the tobacco materials. It uses water as a dispersion medium and has the characteristics of being environmentally friendly, non-toxic, and non-flammable. It is mainly used in tobacco leaf processing, tobacco finishing, cigarette production, etc., including the bonding of cigarette joints, cigarette mouthpieces, filter rod centerlines, strip boxes, and small box packaging to improve the quality and production efficiency of tobacco products. Tobacco materials are the basis of cigarette manufacturing, and to a certain extent determine the quality, grade, and value of cigarette products. They are an important link in the cigarette quality chain. In recent years, with the technical improvements of many domestic cigarette factories and the introduction of high-speed cigarette making machine equipment, the speed of cigarette rolling machines has increased from the original 1,000 sticks / min to a single machine speed of 10,000 sticks / min, which has led to an increasing demand for cigarette adhesives and higher requirements for their quality and performance. Since the running speed of cigarette paper is extremely high (about 600-700m / min) during the operation of high-speed cigarette making machines, higher requirements are put forward in terms of the performance of water-based adhesives for cigarettes.

[0003] Ethylene-vinyl acetate copolymer emulsion (EVA emulsion) is one of the most important water-based adhesive raw materials for cigarettes. Although the existing EVA emulsion-based adhesive has excellent overall performance, it still has problems such as poor initial viscosity, low bonding strength, slow drying speed, and the stability of the emulsion needs to be improved. Starch-based adhesive also has poor bonding and stability, which makes it difficult to meet the requirements of high-speed machinery and was eliminated in the early stage. Summary of the invention

[0004] In view of the above problems, the present invention provides a water-based adhesive for cigarettes and a preparation process thereof.

[0005] The purpose of the present invention is achieved by the following technical solutions: A water-based adhesive for cigarettes, comprising the following components: Acrylic resin emulsion, ethylene-vinyl acetate copolymer emulsion, starch-based component, additives and deionized water; Wherein, the preparation method of the starch-based component comprises the following steps: The starch is placed at 80-100°C for vacuum heat treatment, and then prepared into a dispersion with a mass concentration of 10-40%. After adding polyvinyl alcohol, the pH is adjusted to alkaline. At 30-60°C, a mixed solution of sodium acrylate, rosin and sodium hydroxide is slowly added while stirring. After the addition is completed, the mixture is kept warm and stirred for 1-3 hours. After the reaction is completed, it is cooled, ethanol is added to dilute the reaction system, and the precipitate is separated, washed to neutrality, and dried to obtain the starch-based product.

[0006] In some preferred embodiments, the solid content of the water-based adhesive for cigarettes is 45-50 wt %.

[0007] In some preferred embodiments, the mass ratio of the solid content of the acrylic resin emulsion, the solid content of the ethylene-vinyl acetate copolymer emulsion, the starch-based component, and the auxiliary agent is 10: (8-12): (1.4-3.0): (0.1-0.5).

[0008] In some preferred embodiments, the average molecular weight of the polyvinyl alcohol is between 16,000 and 20,000, and the mass ratio of the starch to the polyvinyl alcohol, the sodium acrylate, the rosin and the sodium hydroxide is 10: (1-1.8): (8-14): (2-3.8): (3-5).

[0009] In some preferred embodiments, the auxiliary agent is one or more of a defoamer, a thickener, and a preservative, wherein the defoamer is polydimethylsiloxane, the thickener is carboxymethyl cellulose or methylated composite modified carboxymethyl cellulose, or its sodium salt or potassium salt; and the preservative is isothiazolone.

[0010] In some preferred embodiments, the acrylic resin emulsion has a solid content of 45-55 wt %, a pH of 7-9, a viscosity of 300-1000 mPa·s, and an average particle size of 150-250 nm.

[0011] In some preferred embodiments, the acrylic resin emulsion is composed of acrylic resin monomer, emulsifier, initiator, buffer, stabilizer and deionized water, the emulsifier is 1-3wt% of the total mass of the monomer, the initiator is 0.1-1wt% of the total mass of the monomer, the buffer is 0.1-0.5wt% of the total mass of the monomer, and the stabilizer is 0.1-0.5wt% of the total mass of the monomer.

[0012] In some preferred embodiments, the acrylic resin monomer is composed of methyl methacrylate, butyl acrylate and methacrylic acid in a mass ratio of 10:(9-12):(1-3).

[0013] In some preferred embodiments, the emulsifier in the acrylic resin emulsion includes a primary emulsifier and an auxiliary emulsifier, the primary emulsifier is sodium dodecyl sulfate; the auxiliary emulsifier is nonylphenol polyoxyethylene ether; the mass ratio of the primary emulsifier to the auxiliary emulsifier is (4-5):1.

[0014] In some preferred embodiments, the initiator in the acrylic resin emulsion is ammonium persulfate, potassium persulfate or sodium persulfate; the buffer is sodium bicarbonate, sodium dihydrogen phosphate or sodium acetate; and the stabilizer is sodium carboxymethyl cellulose.

[0015] In some preferred embodiments, the ethylene-vinyl acetate copolymer emulsion has a solid content of 50-75 wt %, a viscosity of 500-5000 mPa·s, and an average particle size of 100-1000 nm.

[0016] In some preferred embodiments, the ethylene-vinyl acetate copolymer emulsion is composed of monomers, emulsifiers, oxidants, reducing agents and deionized water, wherein the emulsifier is 2-7wt% of the total mass of the monomers, the oxidant is 0.5-1wt% of the total mass of the monomers, and the reducing agent is 0.1-0.5wt% of the total mass of the monomers.

[0017] In some preferred embodiments, the monomers in the ethylene-vinyl acetate copolymer emulsion are composed of vinyl acetate, ethylene and butyl acrylate, and the mass ratio thereof is 100:(10-20):(1-4).

[0018] In some preferred embodiments, the emulsifier in the ethylene-vinyl acetate copolymer emulsion includes octadecyltrimethylammonium bromide and polyvinyl alcohol in a mass ratio of 1:(1-2).

[0019] In some preferred embodiments, the oxidant in the ethylene-vinyl acetate copolymer emulsion is tert-butyl hydroperoxide, and the reducing agent is sodium pyrosulfite.

[0020] Another object of the present invention is to provide a method for preparing the aforementioned water-based adhesive for cigarettes, comprising the following steps: The acrylic resin emulsion and the ethylene-vinyl acetate copolymer emulsion are mixed at 50-70° C., and stirred sufficiently to obtain a mixed emulsion. The starch-based component is added, and the mixture is stirred for 0.5-2 hours at a temperature of 1 000 to 200° C. The auxiliary agent is added and mixed. Finally, the solid content is adjusted with deionized water, and the material is filtered to obtain the product.

[0021] The beneficial effects of the present invention are: Aiming at the problems of poor initial adhesion, low bonding strength, slow drying speed and weak emulsion stability of water-based adhesive for cigarettes based on EVA in the prior art, the present invention prepares a water-based adhesive for cigarettes with high bonding strength, good initial adhesion, fast drying and stable emulsion by modifying composite components, and has good machine applicability. The present invention composites acrylate emulsion and modified starch components on the basis of existing EVA emulsion, and improves the cross-linking curing speed while promoting emulsification. Specifically, the present invention uses starch as a raw material, dehydrates and pre-gelatinizes it through vacuum heat treatment, and then mixes it with polyvinyl alcohol, and performs esterification reaction with acrylic acid and rosin acid under the alkaline condition of sodium hydroxide, and grafts active alkenyl groups and hydrophobic diterpene rosin groups on the hydroxyl groups of starch and polyvinyl alcohol. On the one hand, the active alkenyl groups can participate in the curing of the water-based adhesive, and improve the speed and strength of the cross-linking curing. The polyvinyl alcohol group can protect and stabilize the polymer particles to prevent them from agglomeration and precipitation, and at the same time forms an amphiphilic structure with the hydrophobic diterpene rosin group, effectively promoting the emulsification of the system and improving the stability. DETAILED DESCRIPTION

[0022] The present invention is further described in conjunction with the following examples. Example 1

[0023] A water-based adhesive for cigarettes, comprising the following components: Acrylic resin emulsion, ethylene-vinyl acetate copolymer emulsion, starch-based component, preservative and deionized water; wherein the mass ratio of the solid content of the acrylic resin emulsion to the solid content of the ethylene-vinyl acetate copolymer emulsion, the starch-based component and the preservative is 10:10.9:2.4:0.15; The acrylic resin emulsion is composed of acrylic resin monomer, emulsifier, initiator, buffer, stabilizer and deionized water, wherein the acrylic resin monomer is composed of methyl methacrylate, butyl acrylate and methacrylic acid, and the mass ratio thereof is 10:10:1.8; the emulsifier includes a main emulsifier and an auxiliary emulsifier, wherein the main emulsifier is sodium dodecyl sulfate, and the auxiliary emulsifier is nonylphenol polyoxyethylene ether, and the mass ratio of the main emulsifier to the auxiliary emulsifier is 4.5:1, and the emulsifier is 1.9wt% of the total mass of the monomer; the initiator is ammonium persulfate, and the initiator is 0.4wt% of the total mass of the monomer; the buffer is sodium dihydrogen phosphate, and the buffer is 0.4wt% of the total mass of the monomer; the stabilizer is sodium carboxymethyl cellulose, and the stabilizer is 0.3wt% of the total mass of the monomer; the solid content of the acrylic resin emulsion is 49wt%, the pH is 8.0, the viscosity is 660mPa·s, and the average particle size is 215nm; The ethylene-vinyl acetate copolymer emulsion is composed of monomers, emulsifiers, oxidants, reducing agents and deionized water, wherein the monomers are composed of vinyl acetate, ethylene and butyl acrylate, and the mass ratio thereof is 100:17:2.4; the emulsifier is composed of octadecyltrimethylammonium bromide and polyvinyl alcohol, and the mass ratio thereof is 1:1.7, and the emulsifier is 4.5wt% of the total mass of the monomers; the oxidant is tert-butyl hydroperoxide, and the reducing agent is sodium pyrosulfite, and the oxidant is 0.7wt% of the total mass of the monomers, and the reducing agent is 0.4wt% of the total mass of the monomers; the solid content of the ethylene-vinyl acetate copolymer emulsion is 65wt%, the viscosity is 3500mPa·s, and the average particle size is 520nm; The preparation method of the starch-based component comprises the following steps: The starch is placed at 90°C for vacuum heat treatment to constant weight, and then prepared into a dispersion with a mass concentration of 20%, and the pH is adjusted to 8-10 after adding polyvinyl alcohol, and a mixed solution of sodium acrylate, rosin and sodium hydroxide is slowly added at 50°C while stirring, and the mixture is kept warm and stirred for 2 hours after the addition is completed. After the reaction is completed, the mixture is cooled, ethanol is added to dilute the reaction system, and the precipitate is separated and washed with ethanol solvent and deionized water to neutrality, and dried to obtain the starch-based product; wherein the average molecular weight of the polyvinyl alcohol is 16,000-20,000, and the mass ratio of the starch to the polyvinyl alcohol, the sodium acrylate, the rosin and the sodium hydroxide is 10:1.3:11.8:2.7:4.5; The preservative is 1,2-benzisothiazol-3-one; The preparation method of the water-based adhesive for cigarettes comprises the following steps: At 65° C., the acrylic resin emulsion and the ethylene-vinyl acetate copolymer emulsion are mixed, and the mixed emulsion is fully stirred. The starch-based component is added, and the mixture is stirred for 1.5 hours at the same temperature. The preservative is added and mixed. Finally, the solid content is adjusted to 48wt% with deionized water, and the material is filtered (100 mesh) to obtain the product. Example 2

[0024] A water-based adhesive for cigarettes, comprising the following components: Acrylic resin emulsion, ethylene-vinyl acetate copolymer emulsion, starch-based component, preservative and deionized water; wherein the mass ratio of the solid content of the acrylic resin emulsion to the solid content of the ethylene-vinyl acetate copolymer emulsion, the starch-based component and the preservative is 10:10.9:2.4:0.15; The acrylic resin emulsion and the ethylene-vinyl acetate copolymer emulsion are the same as those in Example 1; The preparation method of the starch-based component comprises the following steps: The starch is placed at 90°C for vacuum heat treatment to constant weight, and then prepared into a dispersion with a mass concentration of 20%, and the pH is adjusted to 8-10. At 50°C, a mixed solution of sodium acrylate, rosin and sodium hydroxide is slowly added while stirring. After the addition is completed, the mixture is kept warm and stirred for 2 hours. After the reaction is completed, it is cooled, ethanol is added to dilute the reaction system, and the precipitate is separated and washed with ethanol solvent and deionized water in turn until neutral, and then dried and mixed with polyvinyl alcohol to obtain the starch-based product; wherein the average molecular weight of the polyvinyl alcohol is 16,000-20,000, and the mass ratio of the starch to the polyvinyl alcohol, the sodium acrylate, the rosin and the sodium hydroxide is 10:1.3:11.8:2.7:4.5; The preservative is 1,2-benzisothiazol-3-one; The preparation method of the water-based adhesive for cigarettes is the same as that in Example 1. Example 3

[0025] A water-based adhesive for cigarettes, comprising the following components: Acrylic resin emulsion, ethylene-vinyl acetate copolymer emulsion, starch-based component, preservative and deionized water; wherein the mass ratio of the solid content of the acrylic resin emulsion to the solid content of the ethylene-vinyl acetate copolymer emulsion, the starch-based component and the preservative is 10:10.9:2.4:0.15; The acrylic resin emulsion and the ethylene-vinyl acetate copolymer emulsion are the same as those in Example 1; The preparation method of the starch-based component comprises the following steps: The starch is placed at 90°C for vacuum heat treatment until constant weight is used for standby use, polyvinyl alcohol is added to deionized water and the pH is adjusted to 8-10, and a mixed solution of sodium acrylate, rosin and sodium hydroxide is slowly added at 50°C while stirring, and the mixture is kept warm and stirred for 2 hours after the addition is completed. After the reaction is completed, the mixture is cooled, ethanol is added to dilute the reaction system, and the precipitate is separated and washed with ethanol solvent and deionized water in turn until neutral, and then dried and mixed with the starch to obtain the starch-based product; wherein the average molecular weight of the polyvinyl alcohol is 16,000-20,000, and the mass ratio of the starch to the polyvinyl alcohol, the sodium acrylate, the rosin and the sodium hydroxide is 10:1.3:11.8:2.7:4.5; The preservative is 1,2-benzisothiazol-3-one; The preparation method of the water-based adhesive for cigarettes is the same as that in Example 1. Example 4

[0026] A water-based adhesive for cigarettes, comprising the following components: Acrylic resin emulsion, ethylene-vinyl acetate copolymer emulsion, starch-based component, preservative and deionized water; wherein the mass ratio of the solid content of the acrylic resin emulsion to the solid content of the ethylene-vinyl acetate copolymer emulsion, the starch-based component and the preservative is 10:10.9:2.4:0.15; The acrylic resin emulsion and the ethylene-vinyl acetate copolymer emulsion are the same as those in Example 1; The preparation method of the starch-based component comprises the following steps: The starch is placed at 90°C for vacuum heat treatment to constant weight, and then prepared into a dispersion with a mass concentration of 20%, and the pH is adjusted to 8-10 after adding polyvinyl alcohol, and a mixed solution of sodium acrylate and sodium hydroxide is slowly added at 50°C while stirring, and the mixture is kept warm and stirred for 2 hours after the addition is completed. After the reaction is completed, the mixture is cooled, ethanol is added to dilute the reaction system, and the precipitate is separated and washed with ethanol solvent and deionized water in turn until neutral, and dried to obtain the starch-based product; wherein the average molecular weight of the polyvinyl alcohol is 16,000-20,000, and the mass ratio of the starch to the polyvinyl alcohol, the sodium acrylate and the sodium hydroxide is 10:1.3:11.8:4.5; The preservative is 1,2-benzisothiazol-3-one; The preparation method of the water-based adhesive for cigarettes is the same as that in Example 1. Example 5

[0027] A water-based adhesive for cigarettes, comprising the following components: Acrylic resin emulsion, ethylene-vinyl acetate copolymer emulsion, preservative and deionized water; wherein the mass ratio of the solid content of the acrylic resin emulsion, the solid content of the ethylene-vinyl acetate copolymer emulsion and the preservative is 10:10.9:0.15; The acrylic resin emulsion and the ethylene-vinyl acetate copolymer emulsion are the same as those in Example 1; The preservative is 1,2-benzisothiazol-3-one; The preparation method of the water-based adhesive for cigarettes is the same as that in Example 1.

[0028]

[0029] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A water-based adhesive for cigarettes, characterized in that: Includes the following components: Acrylic resin emulsion, ethylene-vinyl acetate copolymer emulsion, starch-based component, additives and deionized water; Wherein, the preparation method of the starch-based component comprises the following steps: The starch is placed at 80-100°C for vacuum heat treatment, and then prepared into a dispersion with a mass concentration of 10-40%. After adding polyvinyl alcohol, the pH is adjusted to alkaline. At 30-60°C, a mixed solution of sodium acrylate, rosin and sodium hydroxide is slowly added while stirring. After the addition is completed, the mixture is kept warm and stirred for 1-3 hours. After the reaction is completed, it is cooled, ethanol is added to dilute the reaction system, and the precipitate is separated, washed to neutrality, and dried to obtain the starch-based product.

2. The water-based adhesive for cigarettes according to claim 1, characterized in that: The mass ratio of the solid content of the acrylic resin emulsion, the solid content of the ethylene-vinyl acetate copolymer emulsion, the starch-based component and the auxiliary agent is 10:(8-12):(1.4-3.0):(0.1-0.5).

3. The water-based adhesive for cigarettes according to claim 1, characterized in that: The average molecular weight of the polyvinyl alcohol is between 16,000 and 20,000, and the mass ratio of the starch to the polyvinyl alcohol, the sodium acrylate, the rosin and the sodium hydroxide is 10: (1-1.8): (8-14): (2-3.8): (3-5).

4. The water-based adhesive for cigarettes according to claim 1, characterized in that: The acrylic resin emulsion has a solid content of 45-55wt%, a pH of 7-9, a viscosity of 300-1000mPa·s, and an average particle size of 150-250nm.

5. The water-based adhesive for cigarettes according to claim 1, characterized in that: The acrylic resin emulsion is composed of acrylic resin monomer, emulsifier, initiator, buffer, stabilizer and deionized water, wherein the emulsifier accounts for 1-3wt% of the total weight of the monomer, the initiator accounts for 0.1-1wt% of the total weight of the monomer, the buffer accounts for 0.1-0.5wt% of the total weight of the monomer, and the stabilizer accounts for 0.1-0.5wt% of the total weight of the monomer.

6. The water-based adhesive for cigarettes according to claim 5, characterized in that: The acrylic resin monomer is composed of methyl methacrylate, butyl acrylate and methacrylic acid, and the mass ratio thereof is 10:(9-12):(1-3).

7. The water-based adhesive for cigarettes according to claim 1, characterized in that: The ethylene-vinyl acetate copolymer emulsion has a solid content of 50-75wt%, a viscosity of 500-5000mPa·s, and an average particle size of 100-1000nm.

8. The water-based adhesive for cigarettes according to claim 1, characterized in that: The ethylene-vinyl acetate copolymer emulsion is composed of monomers, emulsifiers, oxidants, reducing agents and deionized water, wherein the emulsifier accounts for 2-7wt% of the total weight of the monomers, the oxidant accounts for 0.5-1wt% of the total weight of the monomers, and the reducing agent accounts for 0.1-0.5wt% of the total weight of the monomers.

9. The water-based adhesive for cigarettes according to claim 8, characterized in that: The monomers are composed of vinyl acetate, ethylene and butyl acrylate, and the mass ratio thereof is 100:(10-20):(1-4).

10. The method for preparing a water-based adhesive for cigarettes according to any one of claims 1 to 9, characterized in that: The following steps are involved: The acrylic resin emulsion and the ethylene-vinyl acetate copolymer emulsion are mixed at 50-70° C., and stirred sufficiently to obtain a mixed emulsion. The starch-based component is added, and the mixture is stirred for 0.5-2 hours at a temperature of 1 000 to 200° C. The auxiliary agent is added and mixed. Finally, the solid content is adjusted with deionized water, and the material is filtered to obtain the product.

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