CN108822241A - A kind of preparation method of environment-friendly type wet strength agent - Google Patents

Abstract

The invention discloses a preparation method of an environment-friendly wet strength agent, which comprises the following steps: mixing styrene, butyl acrylate and glycidyl methacrylate to prepare a mixed monomer; mixing the mixed monomer with deionized water, Add emulsifier and initiator potassium persulfate to carry out pre-emulsification together to obtain pre-emulsified mixed monomer emulsion; add 30 parts by weight of deionized water to a jacketed stirring tank, 15 parts by weight of pre-emulsified mixed monomer emulsion, and open Heating, when the temperature of the material reaches 75 ℃ ~ 85 ℃, keep the temperature constant for 20 minutes, then slowly add the remaining pre-emulsified mixed monomer emulsion, control the addition time in 2 to 4 hours, add the pre-emulsified mixed monomer emulsion After the completion, start to heat up, and when the temperature of the material reaches 90°C, keep the temperature for 1 hour to obtain an environment-friendly wet strength agent emulsion.

Description

A kind of preparation method of environment-friendly wet strength agent

technical field

The invention relates to a preparation method of an environment-friendly wet strength agent, in particular to a preparation method of an environment-friendly wet strength agent for papermaking.

Background technique

Wet strength refers to the paper strength obtained after the paper is wetted in water within a certain period of time. After ordinary paper is wetted, it can only maintain about 2%-10% of its original dry strength. Because the pulp fiber is highly hydrophilic and easy to absorb water, when the paper is in contact with water, under the action of water, its own balance structure is destroyed, so its wet strength is significantly lower than the dry strength. For some paper or cardboard, due to the high requirements for wet strength, the strength of ordinary paper itself cannot meet the demand, so it is necessary to add some additives to the pulp to enhance the wet strength of paper, and the added substances are wet strength agents.

Usually the wet strength of the paper is expressed by the ratio of the wet strength of the paper (the strength of the dry paper after rewetting) to the dry strength, and the strength properties are usually expressed by the tensile strength. By adding wet strength agents, it is possible to produce wet strength papers that retain more than 50% of the dry tensile strength. However, most types of wet strength paper can only retain 20%-40% of the dry tensile strength when soaked in water. Some types of paper, such as toilet paper, may have no wet strength at all if they do not contain wet strength agents, so if such paper retains 10%-20% of its dry tensile strength after being saturated, it is also considered a wet strength paper.

Wet strength papers can also be classified according to their wet strength properties, certain wet strength treatments only slow the rate of strength loss, such papers are said to have temporary wet strength. In addition, some wet strength agents can give paper durable wet strength. Under normal use conditions, the wet strength of this kind of paper remains unchanged for a long time. Therefore, wet strength agents can be divided into permanent wet strength agents and temporary wet strength agents. Permanent wet strength agents include urea-formaldehyde resin (UF), melamine formaldehyde resin (MF), polyamide epichlorohydrin resin (PAE), etc.; temporary wet strength agents include polyethyleneimine (PEI), dialdehyde starch ( DAS), etc.

It should be pointed out that it is not better for all kinds of papers to have higher and more durable wet strength, because most kinds of paper need to be able to be repulped, so the required wet strength depends on the use of the paper. The most important application for wet strength agents is in the production of hygiene tissue, including towels, napkins, cleaning cloths and facial tissues. Packaging paper is another important aspect of wet strength agent applications and includes paper bags, tote bags, milk cartons, freezer packs, meat wraps and fruit bowls. Wet strength agents are also used in various specialty papers, such as poster paper, label paper, overlay tissue paper, wallpaper, sandpaper, map paper, filter paper, electrical insulation paper, photographic paper, banknote paper, and other papers that need to maintain a certain level of stability when wet. Strong paper grade.

UF and MF are typically used in banknote paper and laminated paper, dialdehyde starch is typically used in specialty paper, and polyamide wet strength agents are mainly used in tissue paper, tissue paper, liquid packaging paper, laminated paper, filter paper and high-grade paper , Polyamine wet strength agents are mainly used for container boards, tissue paper and paper towels, while epoxides are mainly used for banknote paper and special paper.

Wet strength additives are all thermosetting resins, which form an insoluble waterproof network body when dried and heated, thus playing a role in humidifying and strengthening the paper. The development mechanism of its action is as follows: (1) In general, low polymers with small molecules and easy to dissolve in water are added to the papermaking process, which can quickly enter the internal structure of the fiber in a short time, and under certain conditions Under this condition, the oligomers condense into high polymers, and the groups of the polymer resin molecules react with the fiber hydroxyl groups to form covalent bonds, thereby enhancing the strength of the paper; (2) Some synthetic high polymers cannot enter the interior of the fibers , deposited between the fibers, and combined with the fibers to form an interpenetrating network structure, which can not only limit the movement between the fibers, but also limit the expansion of the fibers and reduce the possibility of stretching and deformation of the paper sheet, thus protecting the paper in the water molecules It also has a certain strength; (3) The remaining synthetic polymer resins are widely present on the surface of the fiber. After curing, the paper fiber has the advantages of being difficult to dissolve in water and has stable performance, so that the paper will have a good wet strength effect.

During the process of immersing paper in water, the following methods are generally used to maintain a certain strength: 1. By strengthening the surface crosslinking, reducing the immersion of water molecules, strengthening and protecting the formed fiber covalent bonds; 2. By adding auxiliary agent, thus combining into a water-insoluble covalent bond; 3. Resin and fiber are cross-linked to obtain a network structure. Therefore, the reaction mechanism of general humidification includes the following two aspects: the first aspect is the protection mechanism, which is also restricted or homo-crosslinked; the other is the enhanced mechanism, also known as new bond or co-crosslinked. The protection mechanism refers to the chemical reaction between the wet strength agent molecules to form covalent bonds, which will form an interpenetrating network structure on the surface of the fiber and between the gaps, preventing water molecules from entering, and preventing the strength of the paper from decreasing; the strengthening mechanism believes that the resin It reacts with the hydroxyl and carboxyl groups between fibers to obtain covalent bonds, and strengthens the hydrogen bonding between fibers, thereby enhancing the wet strength.

Common wet strength agents include polyethyleneimine (PEI), urea-formaldehyde resin (UF), polyamide epichlorohydrin resin (PAE), etc., all of which have good wet strength effects, but also have some disadvantages, such as urea-formaldehyde resin (UF) and melamine formaldehyde resin (MF), although they were used the first time, they have been banned by various countries in recent years because they contain free formaldehyde, pollute the environment, and restrict their application; PAE has a good wet strength effect, and the demand for it in various countries is increasing day by day, but It is expensive, broken paper is not easy to degrade, and contains carcinogens such as organochlorine; dialdehyde starch (DAS) has been used for a long time, but it has iodide emissions that cause great pollution to the environment, and its usage tends to decrease.

Nowadays, traditional wet strength agents can no longer meet people's needs. In order to better improve paper quality and meet the needs, various new types of wet strength agents have emerged in an endless stream. In view of the requirements of environmental protection, and considering the chemical factors of the wet end, such as the acceptance of pulp, pH value, curing temperature, compatibility with other additives, single-pass retention rate, uniform distribution and anti-interference ability, etc., the development Pollution-free and high-efficiency wet strength agent is an inevitable development trend in the future.

Most of the existing new environmentally friendly cross-linking systems are cross-linking systems that react with fibers. The new wet strength agents using these cross-linking systems have not yet been commercialized because they still have their own shortcomings, such as high cost, too high curing temperature, Make paper brittle and low solid content. Therefore, these new environmentally friendly cross-linking systems still need to be further studied, such as transplanting to natural raw materials to reduce costs, improving the polymerization process to increase molecular weight, developing practical processes, and studying repulping performance.

The polystyrene/glycidyl methacrylate wet strength agent can replace the existing wet strength agent, so as to meet the social requirements for environmental protection, even improve the performance of the wet strength agent, and reduce the cost of wet strength agent preparation.

Chinese patent CN201711303433.4 discloses a preparation method of paper wet strength agent. In the present invention, polylysine is used as raw material, acrylic acid is used as grafting monomer, a polylysine hydrogel is prepared through a crosslinking agent, and then reacted with polyacrylamide to improve the ability to absorb anions, and the paper fiber tape Negative charge, thereby improving its retention rate, while using potassium persulfate as a proton source, under the condition of heating, potassium persulfate slowly decomposes, providing hydrogen ions for polylysine, reducing the hydrophilic property of polylysine, In order to improve the water resistance of paper, in addition, through the alkylation reaction of epichlorohydrin, the introduction of epoxy crosslinking groups increases the crosslinking activity of molecular segments, and further enhances the affinity between polymers and fibers , the cross-linked structure of its molecular chains effectively limits the activities between fibers and fibers, prevents swelling and water absorption of fibers, and thus improves the wet strength of paper.

Chinese patent CN201711102105.8 discloses a composite papermaking wet strength agent and its preparation method. The composite wet strength agent is composed of the following components according to the weight ratio: 5-9 parts of urea-formaldehyde resin, 4-9 parts of carboxymethyl cellulose sodium 7 parts, 8-10 parts of potassium acetate, 2-4 parts of p-toluenesulfonic acid, 4-6 parts of polyethylene glycol, 5-8 parts of acetone, and 105-120 parts of water. The composite wet strength agent of the invention has better stability and dry and wet tensile strength, and can be widely used in the papermaking industry to improve the quality of products.

Chinese patent CN201711088238.4 discloses an environment-friendly papermaking wet strength agent and its preparation method. The environment-friendly papermaking wet strength agent includes the following raw materials in parts by weight: 10-20 parts of diethylenetriamine, 20-30 parts of sodium bicarbonate , 30-50 parts of hydroxyethyl cellulose, 36-40 parts of diethylene glycol diacrylate, 45-50 parts of calcium hexadecanoate, 45-50 parts of cetyl palmitate, 40-40 parts of dimethicone 50 parts, 60-70 parts of cationic polyacrylamide, 40-50 parts of dibasic acid, 20-35 parts of polyol. The preparation method is to stir and react diethylenetriamine, sodium bicarbonate, hydroxyethyl cellulose, diethylene glycol diacrylate and calcium hexadecanoate, add the remaining components after heating up and carry out heat preservation reaction; dropwise add pH adjustment agent. In the preparation process of the wet strength agent, no organic solvent harmful to human body is added, no free formaldehyde is released, and by-products do not pollute the environment, and are environmentally friendly and healthy. The wet strength agent can improve the wet swelling strength and dry swelling strength of paper, and can greatly improve the water resistance of the paper surface.

The object of the present invention is to prepare a highly efficient wet strength agent. Glycidyl methacrylate is selected as the epoxy functional monomer to endow the polymer with a certain reactivity, so that the synthesized wet strength agent can react with the nucleophilic group in the fiber. Cross-linking reaction: Styrene is selected as the hard monomer, and the benzene ring can provide excellent hydrophobicity, and can improve structural strength, film cohesion and wear resistance, and butyl acrylate with a lower glass transition temperature is selected as the soft monomer. Give the copolymer good flexibility, so that the paper will not be brittle.

Contents of the invention

The purpose of the present invention is to provide a preparation method of an environment-friendly wet strength agent to solve the above-mentioned problems in the prior art.

A kind of preparation method of environment-friendly type wet strength agent of the present invention comprises the steps:

A preparation method of an environment-friendly wet strength agent, comprising the steps of: mixing 35-40 parts by weight of styrene, 25-30 parts by weight of butyl acrylate, and 15-20 parts by weight of glycidyl methacrylate to prepare a mixed unit body;

Add 100-120 parts by weight of deionized water into the stirring tank, start stirring, add 0.8-1.2 parts by weight of emulsifier CO436, stir well to disperse the emulsifier evenly; then slowly add mixed monomers into the stirring tank, stir fully to make The mixed monomers are emulsified to form an emulsion, after the mixed monomers are added, 0.5 to 1.0 parts by weight of the initiator potassium persulfate is added, and the initiator potassium persulfate is fully stirred to dissolve the initiator, and finally a pre-emulsified mixed monomer emulsion is obtained;

Add 30 parts by weight of deionized water into a jacketed stirring tank, start stirring, then add 15 parts by weight of the above-mentioned pre-emulsified mixed monomer emulsion, start heating, when the temperature of the material reaches 75°C-85°C, keep the temperature constant for 20 minutes, Then start to slowly add the above remaining pre-emulsified mixed monomer emulsion, control the addition time in 2 to 4 hours, start to heat up after the pre-emulsified mixed monomer emulsion has been added, and keep the temperature for 1 hour when the material temperature reaches 90°C. Environmentally friendly wet strength agent emulsion.

Detailed ways

Example 1

Mix 35kg of styrene, 30kg of butyl acrylate, and 15kg of glycidyl methacrylate to prepare a mixed monomer; add 100kg of deionized water into the stirring tank, start stirring, add 1.2kg of emulsifier CO436, and stir fully to emulsify The agent is evenly dispersed; then slowly add the mixed monomer into the stirring tank, stir fully to emulsify the mixed monomer to form an emulsion, add 1.0 kg of initiator potassium persulfate after adding the mixed monomer, and fully stir to dissolve the initiator potassium persulfate , and finally obtain a pre-emulsified mixed monomer emulsion; add 30 kg of deionized water to a jacketed stirring tank, start stirring, then add 15 kg of the above-mentioned pre-emulsified mixed monomer emulsion, and start heating. When the temperature of the material reaches 85 ° C, Keep the temperature constant for 20 minutes, then slowly add the remaining pre-emulsified mixed monomer emulsion, control the addition time at 3 hours, start to heat up after the pre-emulsified mixed monomer emulsion is added, and keep the temperature for 1 hour when the material temperature reaches 90°C , to obtain an environment-friendly wet strength agent emulsion.

Example 2

Mix 40kg of styrene, 29kg of butyl acrylate, and 20kg of glycidyl methacrylate to prepare a mixed monomer; add 115kg of deionized water into the stirring tank, start stirring, add 1.1kg of emulsifier CO436, and stir fully to emulsify The agent is evenly dispersed; then slowly add the mixed monomer into the stirring tank, fully stir to emulsify the mixed monomer to form an emulsion, add 0.9 kg of initiator potassium persulfate after adding the mixed monomer, and fully stir to dissolve the initiator potassium persulfate , and finally obtain a pre-emulsified mixed monomer emulsion; add 30 kg of deionized water to a jacketed stirring tank, start stirring, then add 15 kg of the above-mentioned pre-emulsified mixed monomer emulsion, and start heating. When the temperature of the material reaches 82 ° C, Keep the temperature constant for 20 minutes, then slowly add the remaining pre-emulsified mixed monomer emulsion, control the addition time at 2.5 hours, start to heat up after the pre-emulsified mixed monomer emulsion is added, and keep the temperature for 1 hour when the material temperature reaches 90°C , to obtain an environment-friendly wet strength agent emulsion.

Example 3

Mix 35kg of styrene, 25kg of butyl acrylate, and 15kg of glycidyl methacrylate to prepare a mixed monomer; add 100kg of deionized water into the stirring tank, start stirring, add 0.8kg of emulsifier CO436, and stir fully to emulsify The agent is evenly dispersed; then slowly add the mixed monomer into the stirring tank, fully stir to emulsify the mixed monomer to form an emulsion, add 0.5 kg of initiator potassium persulfate after adding the mixed monomer, and fully stir to dissolve the initiator potassium persulfate , and finally obtain a pre-emulsified mixed monomer emulsion; add 30 kg of deionized water to a jacketed stirring tank, start stirring, then add 15 kg of the above-mentioned pre-emulsified mixed monomer emulsion, and start heating, when the material temperature reaches 75 °C , keep the temperature for 20 minutes, then start to slowly add the remaining pre-emulsified mixed monomer emulsion, control the addition time at 2 hours, start to heat up after the pre-emulsified mixed monomer emulsion is added, when the temperature of the material reaches 90 ° C, keep the temperature for 1 Hours, an environment-friendly wet strength agent emulsion was obtained.

Example 4

Mix 40kg of styrene, 30kg of butyl acrylate, and 20kg of glycidyl methacrylate to prepare a mixed monomer; add 120kg of deionized water into the stirring tank, start stirring, add 1.2kg of emulsifier CO436, and stir fully to emulsify The agent is evenly dispersed; then slowly add the mixed monomer into the stirring tank, stir fully to emulsify the mixed monomer to form an emulsion, add 1.0 kg of initiator potassium persulfate after adding the mixed monomer, and fully stir to dissolve the initiator potassium persulfate , and finally obtain a pre-emulsified mixed monomer emulsion; add 30 kg of deionized water to a jacketed stirring tank, start stirring, then add 15 kg of the above-mentioned pre-emulsified mixed monomer emulsion, and start heating. When the temperature of the material reaches 85 ° C, Keep the temperature constant for 20 minutes, then start to slowly add the remaining pre-emulsified mixed monomer emulsion, control the addition time at 4 hours, start to heat up after the pre-emulsified mixed monomer emulsion is added, and keep the temperature for 1 hour when the material temperature reaches 90°C , to obtain an environment-friendly wet strength agent emulsion.

Example 5

Mix 38kg of styrene, 27kg of butyl acrylate, and 18kg of glycidyl methacrylate to prepare a mixed monomer; add 110kg of deionized water into the stirring tank, start stirring, add 1.0kg of emulsifier CO436, and stir fully to emulsify The agent is evenly dispersed; then slowly add the mixed monomer into the stirring tank, fully stir to emulsify the mixed monomer to form an emulsion, add 0.8 kg of initiator potassium persulfate after adding the mixed monomer, and fully stir to dissolve the initiator potassium persulfate , and finally obtain a pre-emulsified mixed monomer emulsion; add 30 kg of deionized water to a jacketed stirring tank, start stirring, then add 15 kg of the above-mentioned pre-emulsified mixed monomer emulsion, and start heating. When the temperature of the material reaches 80 ° C, Keep the temperature constant for 20 minutes, then slowly add the remaining pre-emulsified mixed monomer emulsion, control the addition time at 3 hours, start to heat up after the pre-emulsified mixed monomer emulsion is added, and keep the temperature for 1 hour when the material temperature reaches 90°C , to obtain an environment-friendly wet strength agent emulsion.

Claims (1)

1. A preparation method of an environment-friendly wet strength agent, comprising the steps of: mixing 35 to 40 parts by weight of styrene, 25 to 30 parts by weight of butyl acrylate, and 15 to 20 parts by weight of glycidyl methacrylate to prepare mixed monomer; Add 100-120 parts by weight of deionized water into the stirring tank, start stirring, add 0.8-1.2 parts by weight of emulsifier CO436, stir well to disperse the emulsifier evenly; then slowly add mixed monomers into the stirring tank, stir fully to make The mixed monomers are emulsified to form an emulsion, after the mixed monomers are added, 0.5 to 1.0 parts by weight of the initiator potassium persulfate is added, and the initiator potassium persulfate is fully stirred to dissolve the initiator, and finally a pre-emulsified mixed monomer emulsion is obtained; Add 30 parts by weight of deionized water into a jacketed stirring tank, start stirring, then add 15 parts by weight of the above-mentioned pre-emulsified mixed monomer emulsion, start heating, when the temperature of the material reaches 75°C-85°C, keep the temperature constant for 20 minutes, Then start to slowly add the above remaining pre-emulsified mixed monomer emulsion, control the addition time in 2 to 4 hours, start to heat up after the pre-emulsified mixed monomer emulsion has been added, and keep the temperature for 1 hour when the material temperature reaches 90°C. Environmentally friendly wet strength agent emulsion.