Chapter 1 Paper Making Process

The modern papermaking process can be divided into the following main steps: pulping, blending, papermaking, coating, and processing:

Pulping section: raw material selection → cooking and separation of fibers → washing → bleaching → washing and screening → concentration or making into pulp sheets → storage and standby

Modulation paper making section: dispersing pulp → removing impurities → refining pulp → beating pulp → preparing various additives → mixing paper materials → feeding paper materials → head box → mesh section → pressing section → drying section → surface sizing → drying → calendering → coiling into paper

Coating section: coating base paper → coating machine coating → drying → coiling → rewinding → super calendering

Processing section: rewinding → cutting flat plates (or drums) → sorting and packaging → end of warehousing

1、 Pulping:

Pulp is the first step in papermaking, and there are generally three methods for converting wood into pulp: mechanical pulping, chemical pulping, and semi chemical pulping.

Paper making raw materials: There are two categories: plant fibers and non plant fibers (inorganic fibers, chemical fibers, metal fibers).

Bleaching: This section will produce a large amount of black liquor, which is the source of pollution.

2、 Modulation:

The modulation of paper is another key aspect of papermaking, as the strength, color tone, printability, and shelf life of the completed paper are directly related to it. The common modulation process can be roughly divided into the following three steps: dispersing, beating, adding glue, and filling.

（1） Beating: The use of physical methods to treat pulp fibers suspended in water, making them possess the characteristics required for paper machine production, and producing paper and paperboard that meet quality requirements. This operation process is called beating. The effect of beating on fibers: displacement and deformation of cell walls, rupture of outer layers of primary and secondary walls, water absorption and swelling, fine fibrosis, and transverse cutting.

（2） Seasoning:

1. Sizing - By adding a water resistant adhesive material to the slurry, the paper has a certain degree of water resistance and is not easily soaked in water or aqueous solutions. This process is called sizing.

2. Paper and paperboard are divided into different levels of adhesive application——

Re adhesive paper: writing paper, offset printing paper, drawing paper, packaging paper, book cover paper, paper bag paper, etc.

Light adhesive paper: letterpress printing paper, gravure printing paper, typing paper, glossy paper, and coated thick paper, etc.

Non adhesive paper: blotting paper, cigarette paper, roll newsprint, filter paper, toilet paper, impregnated processing paper base paper, denatured processing paper, and steel paper base paper.

（3） Filling: Adding mineral or artificial fillers that are insoluble or insoluble in water to the paper suspension.

3、 Copying process:

Uniformly interweave and dehydrate the thin paper material, and then dry, press, roll, cut, select, and package it. Therefore, the common process is as follows:

1. Paper screening: Dilute the prepared pulp to a lower concentration, and use screening equipment to screen out impurities and undissociated fiber bundles again to maintain quality and protect the equipment.

2. Net part: Make the paper material flow out of the box and evenly distribute and interweave on the circulating copper wire mesh or plastic mesh.

3. Squeezing section: Guide the wet paper with the mesh surface removed to two rollers with woolen cloth, and use the squeezing of the rollers and the water absorption of the woolen cloth to further dehydrate the wet paper and make it tighter to improve the paper surface and increase strength.

4. Drying: Due to the high moisture content of wet paper after pressing, which is still as high as 52-70%, mechanical force can no longer be used to remove moisture. Therefore, the wet paper is allowed to pass through the surface of many cylinders filled with hot steam to dry the paper.

5. Surface gluing - also known as paper surface gluing. It is to immerse the copied paper or paperboard in a sizing agent solution or apply a thin layer of adhesive to the paper surface using a sizing machine. After the sizing agent dries, a layer of liquid resistant adhesive film is formed on the paper surface, making it water resistant. It can also increase the strength and stiffness of the paper, improve its writing performance, improve its friction resistance and durability, and solve the problem of paper shedding and powder. It is commonly used for high-quality paper types, such as banknote paper, securities paper, poker paper, high-end writing paper, and high-end offset printing paper.

6. Calender: Calender is used to improve the smoothness, glossiness, and thickness uniformity of paper.

7. Roll paper: Roll the paper from the calender online into a roll.

4、 Coating: It is the process of applying a layer of coating color to the original paper to give it good optical and printing properties. Its main uses include printing paper for magazines, books, and other publications, as well as printing paper for trademarks, packaging, and product catalogs, with a ratio of approximately 1:3. Coated paper can be divided into: coated paper, coated paper, lightweight coated paper, in addition to special coated paper such as burnished coated paper. The manufacturing of coated paper, in simple terms, refers to applying paint to the base paper, drying it, and then using a calender to smooth its surface. Therefore, the quality of the base paper and the coating are important factors that affect the quality of the coated paper.

5、 Processing: Cutting, sorting, and packaging: Take multiple rolls of paper that have already been rolled into a cylindrical shape at the front, use a paper cutting machine to cut them into sheets, and then manually or mechanically select them to remove damaged or stained paper. Finally, wrap every 500 sheets into a package (usually called a bundle).

Chapter 2 Paper Chemicals

1、 Definition: Papermaking chemicals refer to the general term for various chemical agents and additives used in the papermaking process. It covers a wide range of contents, including four categories: pulping chemicals (such as cooking aids, deinking agents, etc.), papermaking chemicals (such as sizing agents, wet strength agents, etc.), paper processing chemicals (such as fungicides, defoamers, coating agents), and pollution control chemicals. Its purpose is to improve the quality and production efficiency of paper, improve operating conditions, reduce manufacturing costs, increase economic benefits, and develop new paper varieties.

2、 Adhesive:

（1） Classification:

1. Plant gum: rosin, oxidized starch, carboxymethyl cellulose, etc.

2. Animal glue: bone glue, skin glue, casein, stearic acid, etc.

3. Mineral glue: paraffin, water glass, etc.

4. Synthetic adhesive: ethylene ketone dimer, alkenylsuccinic anhydride cationic acrylic ester, etc.

At present, rosin is still the most widely used in the world.

（2） Rosin - is a solid substance obtained by distillation of rosin to remove turpentine oil. It generally contains 80-90% oleic acid, and its molecular formula is C19H29COOH. Grade 4-5 rosin is orange yellow and transparent, making it the most suitable sizing agent for the paper industry. papermaking

Industrial rosin requires a chemical value of 160-180 milligrams of KOH. The content of unsaponifiable matter should be ≤ 9%, volatile matter should be ≤ 0.5%, and the softening point should be between 73 and 78 ℃.

Rosin gum - Rosin is insoluble in water, but can undergo chemical reactions with soda ash and caustic soda to produce sodium rosinate. This reaction is called saponification of rosin, and the resulting particles are called rosin gum. This includes neutral gum (fully saponified), white gum (10% -45% unsaponifiable), high free rosin gum (70% -90% unsaponifiable), and reinforced rosin gum (also known as maleic rosin gum, a highly efficient modified rosin gum).

Reinforced rosin size - With high softening point, high acid value, high saponification value, and strong antioxidant stability, it is used as a papermaking sizing agent with low dosage and good sizing effect.

（3） Sizing agent - sizing agent is a papermaking additive, which can give paper and paperboard ink resistance, water resistance, lotion resistance, corrosion resistance and other properties to improve smoothness, strength and application period. It can be divided into internal sizing agents and surface sizing agents. Pulp sizing agents can be roughly divided into three categories: rosin based sizing agents, synthetic sizing agents, and neutral sizing agents. Surface sizing agents generally use anionic polymer substances.

Sizing agents, also known as in pulp sizing, refer to chemicals added to pulp, paper, and paperboard to achieve fluid penetration resistance. This type of chemical has hydrophilic and hydrophobic groups, which orient the outer side of the fiber surface as hydrophobic groups, endowing the paper with hydrophobicity and fluid permeability resistance. Except for blotting paper, filter paper, wax paper, cigarette paper, household paper, and other types of paper, almost all papers require gluing. Applying glue to paper can improve its water resistance, oil resistance, printing ink resistance, and other properties, while also improving its smoothness, hydrophobicity, and printing adaptability.

There are two methods of sizing. One is to add a sizing agent to the pulp before the paper sheet is formed (during beating or batching), which is called intra pulp sizing. The other is to coat the surface of the paper or paperboard after the paper sheet is formed, which is called surface sizing. The main internal sizing agents include rosin sizing agents, synthetic sizing agents, paraffin sizing agents, and neutral sizing agents. Surface sizing agent and neutral sizing agent. Surface gluing is mainly used to improve the smoothness of the paper surface, reduce porosity, and prevent surface fuzzing and shedding. Modified and unmodified starch are commonly used, and PVA is also used. Other products include paraffin lotion, animal glue, carboxymethyl cellulose, polyurethane, styrene maleic anhydride copolymer, acrylic acid and acrylate copolymer, dihydroxy fatty acid compounds, etc

3、 Filler:

1. Overview - Some solid particles that are basically insoluble in water that are added to the pulp. In order to achieve the purpose of filling, paper fillers should have small and uniform particle size, high whiteness and relative density, stable chemical properties, not easy to react with acid or alkali, not prone to oxidation or reduction, insoluble or insoluble in water, high coverage, refractive index, and scattering coefficient, abundant resources, and low prices. Fillers are generally inorganic mineral based, and organic synthetic fillers have also been developed in recent years. Commonly used include talc powder, kaolin, titanium dioxide, calcium carbonate, etc. There are also special fillers added due to special requirements, such as using carbon black as a filler in conductive paper to enhance conductivity.

2. Function - It has opacity, improving the opacity of paper and making thin paper more suitable for printing on both sides; Can improve the whiteness of paper; Improve the smoothness and uniformity of paper, increase its softness, and make the paper surface smooth and more suitable for printing and writing; It can reduce the moisture absorption and deformation of the paper; Meet the special requirements of paper, etc.

3. Classification - Natural fillers: talc powder, clay (kaolin), calcium carbonate, asbestos, gypsum, barite (barium carbonate), calcined gypsum, etc; Artificial fillers (precipitated calcium carbonate, calcium magnesium white, precipitated calcium sulfate, calcium dioxide, lithopone white, zinc white, sodium aluminosilicate, calcium silicate), etc.

4、 Colorants: There are two main categories: pigments and dyes. Pigments are mostly inorganic compounds (i.e. inorganic pigments) that do not come into direct contact with fibers and are only suitable for paper coating. Dyes are mostly organic compounds, soluble in water, and have alkaline, acidic, direct dyes, and fluorescent brighteners.

Fluorescent brightener: A special dye that can increase the brightness of paper. It can absorb invisible ultraviolet light and turn it into visible light, eliminating the yellow color in the pulp and increasing the visual whiteness of the paper. The main domestic whitening agents include whitening agent R (with red light), whitening agent B (with blue light), and whitening agent VBL (with blue light).

5、 Paper Additives:

1. Cooking aids - Chemicals that can assist in improving cooking efficiency during the pulp making process. They have a chemical effect of removing lignin and a colloidal effect of retaining fiber strength, shortening cooking time, reducing alkali and bleach usage, and improving pulp whiteness and drainage. There are mainly anthraquinone, dihydrodihydroxyanthracene disodium salt, quinone, etc. Dihydrodihydroxyanthracene disodium salt can accelerate delignification speed, shorten cooking time, improve pulping speed, consume less energy, use less alkali and bleaching chemicals, achieve high fiber yield, reduce waste liquid load, and minimize environmental pollution. Odorless. The appropriate dosage for its addition is 0.02%~0.05%.

2. Deinking agent - a chemical or biological product that can separate waste paper fibers from ink. The main function is to break the adhesion of ink to paper fibers, allowing the ink to peel off the fibers and disperse in water. Basic composition:

① Surfactant: It has the functions of permeation, emulsification, dispersion, and washing. It has foaming and stability during flotation, and has a negative/non ionic type.

② Bleaching agent: improves the whiteness of the deinked pulp.

③ Alkali: plays a role in saponification and cleansing.

④ Sodium silicate: plays a buffering, washing, and dispersing role.

Classification: Washing method, flotation method, washing flotation method deinking agent, etc.

Biological enzyme deinking agent:

The main component is alkaline lipase, which directly decomposes ink, coatings, and pigments on waste paper, and can also remove resin from pulp.

Advantages of biological enzyme deinking agents:

① Directly reducing deinking costs, with significant comprehensive cost advantages;

② The biological enzyme deinking conditions are mild, the amount of chemicals used is small, the fiber loss is small, and good fiber characteristics are maintained;

③ Significantly reducing COD and BOD in wastewater is beneficial for environmental protection and reducing wastewater treatment capacity;

④ Effectively handling adhesive issues and improving the efficiency of paper machine operation;

⑤ Do not use or reduce the use of chemicals such as sodium silicate and caustic soda to prevent pipeline scaling;

⑥ Significantly improve pulp yield and paper strength;

⑦ Clean production, saving energy, reducing material consumption ⑧ Easy to use, suitable for most deinking processes nowadays

3. Defoamer, also known as antifoam agent, is used to inhibit and eliminate chemicals that form foam due to various factors in the papermaking process.

Defoamer in slurry: non-ionic organic silicon lotion, dimethyl silicone oil and fumed silica, etc.

Papermaking defoamer: fatty acid ester and non-ionic surfactant, which can eliminate the foam generated during papermaking ingredients, without affecting the paper strength and sizing effect; Emulsified silicone oil defoamer, methyl silicone oil water lotion.

4. Retention aid - a chemical used to improve the retention of fibers and fines in the paper machine mesh.

A. Types of retention aids:

(1) Conventional retention aids - including unit and binary systems. Their characteristic is that high polymers are added to the pressure screen outlet of the paper machine. Conventional retention aids are mainly based on polymers, and alum, polyaluminum chloride (PAC), or fixatives can be added before. The commonly used fixatives are polyamine, polydiallyldimethylammonium chloride, and polyethyleneimine.

(2) Particle retention aid - composed of high polymers such as cationic polyacrylamide and microparticles, it can more effectively overcome the contradiction between flocculation, retention aid, and paper formation uniformity, and is particularly suitable for large high-speed and mesh paper machines. Microparticles are the last chemical added. Commonly used microparticles include bentonite, colloidal silica, and organic micropolymers.

Polymers include:

① Anionic/cationic starch, starch ether type: white powder, used for adding to the wet end of paper making, improving the retention rate of fibers and fillers, and improving paper strength.

② Cationic polyacrylamide: Colorless transparent viscous liquid.

③ Cationic starch and acrylamide graft copolymerization.

④ Acrylamide and sodium acrylate copolymer.

(3) Ultrafine retention aid system - The combination of organic and inorganic particles can achieve better retention and filtration effects. This retention method using two particles is called an ultra-fine retention aid system.

B. Characteristics of retention aids:

(1) Wet end addition: Retention aids are only used in the wet end and are added to the pulp.

(2) Retention and drainage aid: Retention aids must produce retention and drainage aid effects, otherwise they are not retention aids.

(3) Flocculation mechanism: Using "flocculation" as the mechanism of action. Flocculation can be further divided into "flocculation" and "coagulation". The former refers to the process of polymer using long chains to "bridge" and form flocs between different particles; The latter refers to the process of aluminum salts, fixatives, or microparticles relying on charge to aggregate different particles into flocs. Flocculation brings particles closer to each other, which is exactly opposite to the requirement of fiber dispersion for paper formation uniformity. Therefore, retention aids generally have a negative impact on paper formation uniformity, and excessive effectiveness can lead to poor uniformity.

(4) High molecular weight: Polymers play a major role in the retention aid system. If there is no high polymer to produce flocculation, it is difficult to obtain the one-way retention rate required by ordinary paper machines solely relying on other retention chemicals. Therefore, retention aid systems typically include at least one polymer product. Other chemicals, such as aluminum salts, fixatives, and microparticles, are called polymerization aids and mainly play an auxiliary role in conjunction with the use of polymers.

(5) Addition after sieving: The flocs generated by chemical flocculation are easily damaged by shear force, so an appropriate addition point is an important guarantee for the retention agent system to perform its best function. The equipment that generates the greatest shear force in the paper machine sizing system is the slurry pump and pressure screen. In order to avoid strong shear force damaging the flocs, at least one chemical needs to be added after the pressure screen when using retention aids. In general, all retention aid products cannot be added to the pressure screen.

5. Filter aid - a type of auxiliary powder like substance added in filtration operations to reduce filtration resistance, increase filtration rate, or obtain highly clarified filtrate, called a filter aid. Usually, it is a hard powder or fibrous solid. Filter aids are only used for filtration operations aimed at obtaining clean filtrate. There are two types of filter cakes formed by filtration: one type has considerable rigidity and its structure does not change with the increase of operating pressure, called incompressible filter cakes; The structure of another type of filter cake changes with the increase of operating pressure, causing the flow channel of the filtrate in the filter cake to narrow and the flow resistance of the filtrate to sharply increase, which is called a compressible filter cake. For compressible filter cakes, adding filter aids can enhance their rigidity and prevent an increase in filtration resistance. When filtering suspensions containing viscous fine particles, a dense cake layer is often formed. Adding filter aids can change the cake structure and reduce cake resistance. The use method of filter aid: one is to mix the filter aid with the suspension to be filtered in a certain proportion, and then filter together; Another method is to prepare a suspension containing only filter aids, filter it first, form a pre coating on the filter medium, and then filter the filter slurry. The pre coating of filter aid can withstand a certain pressure without deformation, and can prevent the filter cloth from increasing resistance due to blockage.

Classification: Commonly used filter aids include diatomaceous earth, paper pulp, activated carbon, metal shavings, acidic clay, asbestos, cellulose, and slag. Diatomaceous earth has a large specific surface area, which can adsorb colloidal substances and form filter cakes with high porosity, making it the most widely used filter aid. Paper pulp is often used as a pre coating to prevent early blockage of the filter cloth.

Basic requirements:

① Rigid particles that can form a porous cake layer provide good permeability and low fluid resistance for the filter cake.

② Has chemical stability.

③ It has incompressibility within the operating pressure range.

6. Reinforcement agent - suitable for neutral or acidic sizing systems or non sizing systems, with a retention rate of over 95%. After using the reinforcement agent, some low-grade pulp raw materials can be used to replace high-grade wood pulp, improve the pulp grade, save wood pulp usage, and reduce production costs.

Dry strength agents - Currently, the main dry strength enhancing agents are low to medium molecular weight ionic acrylamide copolymers, as well as resins such as polyurethane and polyamide. The use of a small amount of desiccant can significantly improve the physical strength of paper, such as bursting, folding, and tensile strength; Under the condition of maintaining the original strength of the paper, some cheap raw materials such as waste paper and machine wood pulp can be used to replace high-quality coniferous wood pulp; Or increase the amount of fillers to save fiber raw materials, etc.

Wet strengthening agent - Adding wet end to papermaking can achieve good wet strength and be used as a wet strengthening agent for absorbent paper. After paper or cardboard is completely saturated with water, it can still maintain its original dry strength of 20-40%. Many special types of paper, such as photographic paper, banknote paper, frozen food packaging, tea paper, etc., must have a certain wet strength.

Mainly thermosetting synthetic resins, such as melamine formaldehyde resin, urea formaldehyde resin, polyvinyl alcohol, polyamine polyamide epichlorohydrin resin, etc.

7. Resin control agent - a chemical that can prevent the precipitation of free resin from wood pulp or the agglomeration of residual ink from waste paper during the papermaking process, causing production obstacles. In the early days, starch or gelatin was added to the pulp as a protective colloid to prevent resin condensation, and sodium hydroxide or alum was used to adjust the acid value to prevent resin precipitation. However, the effect was not significant. Later, soft water agents such as ammonium carboxylate chelates were used to chelate with metal ions such as calcium, magnesium, and iron in water to eliminate their harmful effects. In recent years, resin control agents have been developed, consisting of organic dispersants such as sodium polyacrylate and sodium methylene naphthalene sulfonate, as well as non ionic surfactants such as polyoxyethylene alkylphenol ethers. These agents can disperse resin particles and reduce adhesion, thereby avoiding obstacles caused by agglomeration.

8. Coating processing aids - a series of chemicals that can improve the quality of coatings, endow special properties, or ensure the normal operation of coating processing. Mainly including:

① Dispersant: used to reduce the viscosity of high concentration coatings and give them good rheological properties.

② Lubricant: used to enhance the rheological properties of coatings, reduce friction coefficient, and reduce the roller sticking phenomenon of coated paper during super calendering.

③ Solvent resistance: used to improve the water resistance of coating adhesives such as starch, casein, and polyvinyl alcohol. It can increase the wet friction resistance of the coating and the pulling strength of the paper surface.

④ Rheological improver for coatings: used to adjust the viscosity of coatings to adapt to various coating processes. Reducing the viscosity of coatings is called a viscosity reducer, such as urea, dicyandiamide, etc; Increasing the viscosity of coatings is called a thickener or water retaining agent, such as acrylate copolymers, cellulose derivatives, etc. A viscosity reducing agent can maintain appropriate rheological properties of the coating, avoiding problems such as peeling, streaking, or arching of the coated paper. During the coating process, other additives such as defoamers, preservatives, fluorescent brighteners, etc. must also be added.

9. Coatings for coating - water-based coatings are commonly used. The composition of water-based coatings can be roughly divided into four categories: pigments, adhesives, additives, and water. The combination of these four components is closely related to the quality of the coated paper.

① Pigments - including white clay, calcium carbonate, sardine white, aluminum hydroxide, titanium dioxide, and plastic pigments. Generally, it can be divided into three types: binder type, solid type, and hollow type, with the latter two being more commonly used.

The characteristics that pigments need to possess:

The particle size should be appropriate. In general, a smaller particle size is more conducive to improving the whiteness, opacity, and glossiness of paper.

However, if the particle size is too small, it will increase its surface area, leading to an increase in the viscosity of the pigment coating, a decrease in flowability, and an increase in the amount of adhesive required.

The shape of pigment particles should also be appropriate. Needle shaped pigment particles have poor flowability, while hexagonal and spherical pigment particles have better flowability, and can form a porous coating layer to improve the ink absorption of the paper.

High whiteness and opacity (strong masking ability).

It is easily dispersed in water and has good stability and fluidity.

(5) It has better chemical stability and the amount of adhesive used should be minimized as much as possible.

Low wear resistance (reducing wear on coating machines and printing plates).

② Adhesives - Adhesives are divided into natural and synthetic substances, including starch, cheese, soy protein, etc. Synthetics include various synthetic emulsions, polyvinyl alcohol, etc. The most widely used now is a mixture of starch and synthetic latex. The proportion of synthetic latex used is constantly increasing, and recently all latex based adhesives have been developed, which is consistent with the high concentration development of coatings. The following requirements apply to any adhesive:

⑴ Has strong adhesion to pigments.

⑵ It has good adaptability and stability to pigments, but does not undergo chemical reactions with pigments.

(3) Have appropriate viscosity and film-forming properties.

(4) Have appropriate fluidity to facilitate coating operations and improve coating uniformity.

The color should be light, free of impurities and foreign objects, and have good paint operability.

Due to the fact that general adhesives, whether natural or synthetic, still have some properties that cannot be improved, there has been the emergence of so-called auxiliary adhesives (co binders) in recent years to supplement the insufficient water retention and fluidity of adhesives. Their dosage is only about 10-30% of the total adhesive dosage. Currently, some factories are also trying to use this to reduce the total adhesive dosage. Due to its small dosage, it can sometimes be considered as an additive. The commonly used auxiliary adhesives currently include soy protein and rheoloe mdiffer.

③ Additives - including dispersants, lubricants, preservatives, fluorescent agents, water resistant agents, as well as dyes, ink absorbents, and modifiers. Their main function is to supplement the deficiencies of pigments and adhesives and reduce operational difficulties.

6、 Chemical additive variety:

1. Softening and puffing agent - used to increase the fluffiness of paper, specifically for toilet paper and superstition paper. Increase the volume of toilet paper and improve its water absorption. The water absorption should be large and the quality should be good. Appearance: White solid powder, effective content ≥ 95%, non ionic. Used to increase softness, it can significantly improve the flexibility of household and cultural paper. The fried paper has a good hand feel, fine and even wrinkling, and has varying degrees of improvement in tensile strength and whiteness.

2. Waterproof agent——

3. Starch cross-linking agent for surface application of corrugated paper - a substance that can bridge molecules and cause multiple linear molecules to bond and crosslink into a network structure, commonly known as "curing agent", "hardening agent", "curing agent", etc. A composite reinforcing agent specifically designed for surface sizing starch for curing and strengthening. Adding it to gelatinized starch can increase the ring compression strength, tensile strength, retention rate, and water resistance of corrugated paper. It is an important additive for corrugated base paper, and the ring compression strength is generally increased by 20-30% (increasing 1-2 ring compression indices). White powder. More than 96%. Cationic, with a pH value of 4-6, easily soluble in cold water.

4. Paper coated polyester defoamer - a broad-spectrum defoamer made of polyether fatty acid ester liquid, can eliminate or inhibit the generation of foam in the aqueous phase system, especially for water-soluble polymers and medium and high viscosity systems.

5. Ink adsorbent - used in the regeneration of ink fibers and the reuse of secondary fibers, to overcome the adhesive substances and ink resin problems that cause paper defects in fibers. It is currently an ideal additive for the reuse of secondary fibers. Powdered solid, insoluble in water, containing ions, capable of forming dispersions in water. It has good dispersibility, sizing effect, and retention, which can improve various physical properties and retention rate of paper products, increase dosage, and will not increase production costs.

6. Cationic polyacrylamide - a linear polymer formed by copolymerization of cationic monomers and acrylamide, with functions such as decolorization, adsorption, turbidity removal, and adhesion. Usage: sludge dewatering agent, papermaking additive, sewage and organic wastewater treatment, oilfield chemical agent, etc.

7. Honeycomb paper flame retardant - can be used to treat various honeycomb paper products, natural wood, artificial boards, wooden products, and processed parts; It is also used for fabrics such as bamboo, linen, cotton, as well as plant fiber materials or products. After treatment, the material does not change its original appearance luster and physical and mechanical properties. When encountering an open flame, it will not burn and only shows local carbonization, which can effectively suppress the spread of flames and prevent the spread of fires.

8. Hardening agent - applied in the production process of various types of paper and paperboard, to significantly increase the dry strength of paper and paperboard, reduce high-quality raw material consumption, reduce production costs, or improve product grade. Synthesis of modified polyamide resin, belonging to the amphoteric composite type and near electric neutrality. The effect on the drying strength of corrugated paper is particularly significant. Enhance the moisture resistance of paper.

9. During the alkali recovery process of paper making black liquor evaporator, a special scale inhibitor - paper making black liquor. Due to the high temperature, strong alkalinity, high content of silicon, magnesium, calcium, oxalate, and solid substances, as well as high viscosity of paper making black liquor, the evaporator scales very seriously and even becomes blocked. It has to be stopped for cleaning, which increases costs and affects production, becoming a problem that has always troubled alkali recovery.

The special scale inhibitor for paper black liquor evaporators is composed of various components such as surfactants, dispersants, and viscosity reducers. When the scale inhibitor is added to papermaking black liquor, the viscosity reducer in the scale inhibitor reacts with silicon, oxalates, and various sugars in the black liquor, causing it to lose its viscosity and be suspended in the black liquor. Surfactants and dispersants maximize the dispersion of scaling ions such as calcium, magnesium, and silicon in the black liquor, increasing its anti precipitation and flowability, making it unsuitable for sedimentation and adhesion on the surface of the evaporator, while keeping the evaporator surface clean and free of scale. The dispersant will also react chemically with the dirt on the surface of the evaporator, causing the old dirt to dissolve and fall off, achieving the goal of removing the old dirt. Due to the decrease in viscosity of black liquor, the growth of new scales is prevented, and the removal of old scales increases the heat conduction rate. The evaporation rate of water in black liquor accelerates, shortening the time required for black liquor evaporation, and making the entire alkali recovery process more efficient and energy-saving, with significant benefits. Solid content ≥ 40%, pH value (1% aqueous solution) 8.0-10.0%

10. Pulp dispersant - Anionic or composite polymer, which can effectively disperse pulp fibers. Improving the uniformity of pulp and the softness of paper is an important additive in the production of toilet paper. It is also widely used in the production of cultural paper, glossy thin paper, and newsprint. It can prevent holes, improve the smoothness, and have a good hand feel in the paper. It can also increase the speed of the papermaking process, save pulping time, reduce energy consumption, and have significant economic benefits. White bright small particles and slightly yellow bright particles, with an effective content of ≥ 98% and a molecular weight of 15-20 million units. With its extremely small dosage, it exhibits a unique dispersion effect and can save pulp, increasing paper yield by 5-10%. Increase the retention rate of fine fibers and additives, and reduce the concentration of filtered water under the mesh. It can be used in a wide range of pH values from 4 to 10. In the application of paper-making coating, the paper-making dispersant has high dispersion efficiency, stable paint viscosity, less foam, non-toxic, non corrosive, which can improve the solid content of the paint, and has good fluidity and scrub resistance, which can maintain the gloss of the paper and is not easy to become moldy. Paper dispersants can also increase the speed of papermaking, save beating time, reduce energy consumption, and have significant economic benefits.