A paper surface sizing agent and its preparation method

Abstract

This invention discloses a paper surface sizing agent, comprising cationic monomers, hydrophobic monomers, modified monomers, cationic starch, styrene, butyl acrylate, and hydroxyethyl acrylate. This paper surface sizing agent, by introducing multiple functional monomers, including hydrophobic monomers, cationic monomers, and modified monomers, and combining styrene, butyl acrylate, and hydroxyethyl acrylate monomers to graft copolymerize and modify cationic starch, yields a multifunctional polymer copolymer with relatively low cost. After film formation, it can effectively crosslink and bind to the paper fiber surface, forming a multidimensional spatial hydrophobic network structure on the paper surface, achieving the dual effect of effectively reducing the Cobb value of paper and increasing paper strength, thereby effectively improving the water resistance and surface strength of paper.

Description

Technical Field

[0001] This invention relates to a paper surface treatment agent, specifically to a paper surface sizing agent and its preparation method. Background Technology

[0002] In the modern papermaking industry, with the development of paper coating technology, we have placed higher demands on coating pigments and additives. Coatings not only protect the value of the coated object, but also play a good decorative role due to their rich colors. Today, with people's increasing environmental awareness, the development of water-based coatings has been strongly advocated, and solid components such as pigments and fillers occupy an important part of the coating.

[0003] Conventional paper and paperboard are mainly composed of plant fibers, which have good hygroscopic properties. Because the narrow gaps between fibers in wet paper act as capillary magnets, untreated paper easily absorbs moisture. Therefore, sizing is an indispensable process in papermaking. By adding sizing agents and processing the pulp, paper, or paperboard under certain conditions, the aim is to form a hydrophobic protective film on the paper surface, which acts as a water-resistant agent and reduces the hydrophilic properties of the plant fibers.

[0004] The current development trend of the paper market, especially corrugated paper and board paper, faces increasingly serious problems, mainly reflected in reduced basis weight, deteriorating pulp quality, and unstable quality of internally sized paper. Therefore, a superior paper sizing agent is needed to protect and control the water resistance of finished paper, improve paper strength, and enable rapid curing. Currently, there are many types of sizing agents on the market, which are used in large quantities, are costly, and their overall effects are not comprehensive enough. Summary of the Invention

[0005] To overcome the above-mentioned shortcomings, one of the objectives of this invention is to provide a paper surface sizing agent to improve the waterproof performance of paper or paperboard, increase the surface strength of paper, achieve comprehensive performance of rapid curing, and with a small amount of surface sizing agent added, the effect is obvious and more comprehensive, reduces costs, and is green and environmentally friendly.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a paper surface sizing agent, comprising cationic monomers, hydrophobic monomers, modified monomers, cationic starch, styrene, butyl acrylate and hydroxyethyl acrylate.

[0007] Further, by weight, the cationic monomer is 2-4 parts, the hydrophobic monomer is 3-6 parts, the modified monomer is 1-2 parts, the cationic starch is 40-80 parts, the styrene is 60-120 parts, the butyl acrylate is 40-80 parts, and the hydroxyethyl acrylate is 6-12 parts.

[0008] For example, the cationic monomer is in the range of 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, or any two of these.

[0009] The hydrophobic monomer is in the range of 3 parts, 4 parts, 5 parts, 6 parts, or any two of these.

[0010] The modified monomer is in the range of 1 part, 1.5 parts, 2 parts, or any two of these.

[0011] The cationic starch is in the range of 40 parts, 50 parts, 60 parts, 70 parts, 80 parts, or any two of these.

[0012] The range of styrene consisting of 60 parts, 70 parts, 80 parts, 90 parts, 100 parts, 110 parts, 120 parts, or any two of these;

[0013] The butyl acrylate is in the range of 40 parts, 50 parts, 60 parts, 70 parts, 80 parts, or any two of these.

[0014] The hydroxyethyl acrylate is in the range of 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, or any two of these.

[0015] Furthermore, it also includes 0.2-0.5 parts of modified wollastonite, 0.2-0.5 parts of modified bentonite, and 1.0-2.0 parts of polyamide-polyurea resin.

[0016] For example, the modified wollastonite is composed of 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, or any two of these; the modified bentonite is composed of 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, or any two of these; and the polyamide-polyurea resin is composed of 1.0 parts, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, 1.7 parts, 1.8 parts, 1.9 parts, 2.0 parts, or any two of these.

[0017] Furthermore, the modified wollastonite is 600-mesh fibrous papermaking grade wollastonite modified by silane coupling agent KH-550 and dodecylamine, and the wollastonite has a Mohs hardness range of 5.0-5.5.

[0018] The modified bentonite is bentonite modified by sulfuric acid acidification.

[0019] The polyamide-polyurea resin content is 50%.

[0020] Further, the weight ratio of the hydrophobic monomer to the modified monomer is 1.0-3.0:1. For example, the weight ratio of the hydrophobic monomer to the modified monomer is 1.0:1, 1.5:1, 2.0:1, 2.5:1, or 3.0:1.

[0021] Furthermore, the cationic monomer is selected from one or two of dimethyl diallyl ammonium chloride and dimethylaminopropyl methacrylamide;

[0022] The hydrophobic monomer is selected from one or more of benzyl acrylate, benzyl methacrylate, and methyl 2-benzyl acrylate;

[0023] The modified monomer is selected from one or more of divinyltetramethyldisiloxane, tetramethyltetravinylcyclotetrasiloxane, and hexamethylhexavinylcyclohexasiloxane;

[0024] The cationic starch is cationic cassava modified starch, with a content of 88% by weight.

[0025] Furthermore, it also includes 0.05-0.10 parts of α-amylase, 3-5 parts of cationic emulsifier, and 6-10 parts of glacial acetic acid; exemplaryly, the α-amylase is in the range of 0.05 parts, 0.06 parts, 0.07 parts, 0.08 parts, 0.09 parts, 0.10 parts, or any two of these; the cationic emulsifier is in the range of 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, or any two of these; and the glacial acetic acid is in the range of 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, or any two of these.

[0026] The α-amylase is a liquid mesophilic α-amylase with an enzyme activity of 4000 U / g;

[0027] The cationic emulsifier is one or both of dodecyl dimethyl benzyl ammonium chloride and benzyl trimethyl ammonium chloride.

[0028] Furthermore, it also includes an initiator and a reducing agent, wherein the initiator includes one or more of ammonium persulfate, potassium persulfate, and sodium persulfate; and the reducing agent includes one or more of sodium bisulfite, potassium bisulfite, and ammonium bisulfite.

[0029] Another object of the present invention is to provide a method for preparing a paper surface sizing agent, comprising the following steps:

[0030] S1. Preparation of preemulsion A: Add 50-100 parts of water and 3-5 parts of cationic emulsifier to the emulsification kettle, stir evenly, then add 60-120 parts of styrene, 40-80 parts of butyl acrylate, 6-12 parts of hydroxyethyl acrylate, 3-6 parts of hydrophobic monomer, 2-4 parts of cationic monomer, and 1-2 parts of modified monomer in sequence, stir evenly, the stirring speed is 300-400 r / min, the stirring time is 20-30 min, and preemulsion A is prepared.

[0031] S2. Preparation of initiator solution B: Dissolve 3-6 parts of initiator in 45-90 parts of water to prepare initiator solution B;

[0032] S3. Preparation of reducing agent solution C: Dissolve 0.5-1 part of reducing agent in 10-20 parts of water to prepare reducing agent solution C;

[0033] S4. Add 230-460 parts water, 40-80 parts cationic starch, and 0.05-0.10 parts α-amylase to the reaction vessel, stir evenly and heat, further raising the temperature to 70-80℃, and keep warm and stirring for 20-40 minutes; after the reaction is completed, add 6-10 parts glacial acetic acid to the reaction vessel to terminate the enzymatic hydrolysis reaction, and keep warm for 5-10 minutes.

[0034] S5. Add a portion of pre-emulsion A, which accounts for 10% of the mass of pre-emulsion A prepared in S1. Then add a portion of initiator solution B to carry out a water-soluble polymerization reaction, which accounts for 20% of the mass of initiator solution B prepared in S2. The reaction time is 20-30 min.

[0035] Add the remaining pre-emulsion A and the remaining initiator solution B dropwise to carry out emulsion polymerization reaction. The reaction temperature is 75-83℃. The reaction time for adding the remaining pre-emulsion A is 90-120 min, and the reaction time for adding the remaining initiator solution B is 100-130 min. After the reaction is completed, keep the reaction at the temperature for about 60-90 min.

[0036] S6. After the heat preservation is completed, cool down to 70-75℃, add reducing agent solution C dropwise, and finish adding in 20-30 minutes. Keep the reaction at the heat for 20-30 minutes.

[0037] S8. Cool down to below 40℃, add 0.2-0.5 parts of modified wollastonite and 0.2-0.5 parts of modified bentonite respectively, stir for 30-40 minutes, then add 1.0-2.0 parts of polyamide polyurea resin (PAPU) and stir for another 30-40 minutes. Add an appropriate amount of water to adjust the product solid content to 29%-31%, and the final product is obtained.

[0038] The beneficial effects of this invention are:

[0039] 1) The paper surface sizing agent of this invention introduces a variety of functional monomers, including hydrophobic monomers, cationic monomers and modified monomers. It combines styrene, butyl acrylate, hydroxyethyl acrylate and other monomers to graft copolymerize and modify cationic starch to obtain a multifunctional polymer copolymer with relatively low cost. After film formation, it can effectively crosslink and bind to the paper fiber surface, and form a multidimensional spatial hydrophobic network structure on the paper surface, achieving the dual effect of effectively reducing the paper Cobb value and improving the paper strength, thereby effectively improving the paper's water resistance and surface strength.

[0040] 2) By controlling the mass ratio of the hydrophobic monomer benzyl methacrylate to the modified monomer tetramethyltetravinylcyclotetrasiloxane to 1.0-3.0:1, and combining a certain amount of cationic monomers, the main chain structure of the cationic sizing agent polymer has more hydrophobic cationic group-modified branches. This allows the sizing agent to achieve good water and moisture resistance and improve paper strength with only a small amount of application when combined with paper fibers.

[0041] 3) Introduce modified monomers containing siloxane (one or more of divinyltetramethyldisiloxane, tetramethyltetravinylcyclotetrasiloxane, and hexamethylhexavinylcyclohexasiloxane), and utilize the cross-linking hydrophobic effect of organosilicon monomers to combine with the hydrophobic ester groups and hydroxyl groups contained in the original polymer to form a strong water-resistant effect with multiple hydrophobic groups layered on top of each other, further improving the overall water resistance of the paper.

[0042] 4) The introduction of 600-mesh fibrous papermaking-grade wollastonite modified with silane coupling agent KH-550 and dodecylamine, and bentonite modified by sulfuric acid acidification, can make the surface sizing agent polymer firmly adsorbed on the paper surface and form a high-hardness multi-dimensional network protective film structure on the paper surface. This comprehensively improves the water resistance and hardness of the original paper protective film, thereby significantly improving the film-forming water resistance and film strength of the surface sizing agent. The surface sizing agent after joint micro-modification has better water resistance and higher strength.

[0043] 5) When the sizing agent of the present invention is added to the application evaluation system containing starch, it can enable more effective cross-linking between the sizing agent, the starch system and the paper fibers. In addition, the polyamide polyurea resin (PAPU) contained in the sizing agent enables the original sizing agent to quickly form a film and mature, and more firmly adsorb onto the paper surface, thereby further improving the water resistance and overall stability of the paper.

[0044] 6) Comparative experiments on surface sizing performance show that the paper surface sizing agent of the present invention has excellent water resistance. Furthermore, compared with the uniform addition amount of currently commercially available surface sizing agents, the surface sizing agent of the present invention requires less dosage, achieves better results, and is less expensive. When used on paperboard, corrugated paper, and other types of paper, the resulting finished paper exhibits excellent water resistance and good paper strength, while improving paper smoothness and gloss. Detailed Implementation

[0045] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0046] Unless otherwise shown or indicated in the operational embodiments, all figures used to represent the amounts, physicochemical properties, etc., of ingredients in the specification and claims are to be understood to be adjusted by the term "about" in all cases. Therefore, unless stated to the contrary, the numerical parameters listed in the foregoing specification and appended claims are approximations, and those skilled in the art can appropriately modify these approximations to obtain the desired characteristics by utilizing the teachings disclosed herein. The use of numerical ranges indicated by endpoints includes all numbers within that range and any range within that range; for example, 1 to 5 includes 1, 1.1, 1.3, 1.5, 2, 2.75, 3, 3.80, 4, and 5, etc.

[0047] The applicant has observed increasingly serious problems in the current paper market, particularly in corrugated paper and cardboard, primarily manifested in reduced basis weight, deteriorating pulp quality, and unstable quality of internally sized paper. Therefore, a superior paper sizing agent is needed to protect and control the water resistance of finished paper, improve its strength, and facilitate rapid curing. Currently, there are many types of sizing agents on the market, requiring large quantities, resulting in high costs, and their overall effectiveness is not comprehensive enough.

[0048] To address the aforementioned technical problems, this invention provides a paper surface sizing agent. This agent is produced by emulsifying and polymerizing various functional monomers in specific proportions to obtain a multifunctional polymer copolymer. The polymer contains a large number of hydrophobic ester, hydrocarbon, and siloxane groups, which, after film formation, can effectively cross-link and bond to the paper fiber surface, forming a multidimensional hydrophobic network structure. This achieves the dual effect of effectively reducing the Cobb value and improving the surface strength of the paper. A small amount of modified wollastonite and modified bentonite are incorporated to ensure the polymer adheres more firmly and uniformly to the paper surface, thereby comprehensively enhancing the water resistance and hardness of the original paper protective film. Furthermore, the addition of an appropriate amount of polyamide-polyurea resin (PAPU) coordinates and optimizes the polymer, allowing the sizing agent to mature more rapidly on the paper surface, further improving its cross-linking properties with the paper fibers and enhancing the overall water resistance and strength of the paper.

[0049] The specific preparation steps for paper surface sizing agents are as follows:

[0050] S1. Preparation of preemulsion A: Add 50-100 parts of water and 3-5 parts of cationic emulsifier to the emulsification kettle, stir evenly, then add 60-120 parts of styrene, 40-80 parts of butyl acrylate, 6-12 parts of hydroxyethyl acrylate, 3-6 parts of hydrophobic monomer, 2-4 parts of cationic monomer, and 1-2 parts of modified monomer in sequence, stir evenly, the stirring speed is 300-400 r / min, and the stirring time is 20-30 min, to prepare preemulsion A.

[0051] The cationic emulsifier is selected from one or both of dodecyl dimethyl benzyl ammonium chloride and benzyl trimethyl ammonium chloride.

[0052] The hydrophobic monomer is selected from one or more of benzyl acrylate, benzyl methacrylate, and methyl 2-benzyl acrylate;

[0053] The cationic monomer is selected from one or two of dimethyl diallyl ammonium chloride and dimethylaminopropyl methacrylamide;

[0054] The modified monomer is selected from one or more of divinyltetramethyldisiloxane, tetramethyltetravinylcyclotetrasiloxane, and hexamethylhexavinylcyclohexasiloxane.

[0055] S2. Preparation of initiator solution B: Dissolve 3-6 parts of initiator in 45-90 parts of water to prepare initiator solution B; the initiator is selected from one or more of ammonium persulfate, potassium persulfate, and sodium persulfate.

[0056] S3. Preparation of reducing agent solution C: Dissolve 0.5-1 part of reducing agent in 10-20 parts of water to prepare reducing agent solution C; the reducing agent is selected from one or more of sodium bisulfite, potassium bisulfite, and ammonium bisulfite.

[0057] S4. Add 230-460 parts water, 40-80 parts cationic starch, and 0.05-0.10 parts α-amylase to the reaction vessel, stir evenly and heat, further raising the temperature to 70-80℃, and keep warm and stirring for 20-40 minutes; after the reaction is completed, add 6-10 parts glacial acetic acid to the reaction vessel to terminate the enzymatic hydrolysis reaction, and keep warm for 5-10 minutes.

[0058] The cationic starch is cationic modified cassava starch, with a content of 88% by weight. The α-amylase is a liquid mesophilic α-amylase with an enzyme activity of 4000 U / g.

[0059] S5. Add a portion of pre-emulsion A, which accounts for 10% of the total mass of pre-emulsion A prepared in S1. After 1 minute, add a portion of initiator solution B to carry out the water-soluble polymerization reaction. The initiator solution B accounts for 20% of the mass of initiator solution B prepared in S2. The reaction time is 20-30 minutes.

[0060] Add the remaining pre-emulsion A and the remaining initiator solution B dropwise to carry out emulsion polymerization reaction. The reaction temperature is 75-83℃. The reaction time for adding the remaining pre-emulsion A is 90-120 min, and the reaction time for adding the remaining initiator solution B is 100-130 min. After the reaction is completed, keep the reaction at the temperature for about 60-90 min.

[0061] S6. After the heat preservation is completed, cool down to 70-75℃, add reducing agent solution C dropwise, and finish adding in 20-30 minutes. Keep the reaction at the heat for 20-30 minutes.

[0062] S7. Cool to below 40℃, add 0.2-0.5 parts of modified wollastonite and 0.2-0.5 parts of modified bentonite respectively, and stir for 30-40 minutes. Then add 1.0-2.0 parts of polyamide-polyurea resin (PAPU) and stir for another 30-40 minutes. Add an appropriate amount of water to adjust the solid content of the product to obtain the final product. The solid content of the paper surface sizing agent is 29%-31%. The polyamide-polyurea resin (PAPU) was purchased from Wuxi Tianxin Chemical Co., Ltd., model LWR-02 (PAPU).

[0063] Example

[0064] The following examples describe the disclosure of this invention in more detail. These examples are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of this disclosure. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are based on weight, and all reagents used in the examples are commercially available or synthesized by conventional methods and can be used directly without further processing. The instruments used in the examples are also commercially available.

[0065] Example 1

[0066] S1. Add 50g of water and 3g of cationic emulsifier dodecyl dimethyl benzyl ammonium chloride to a pre-emulsifier. Under stirring conditions, add 60g of styrene, 40g of butyl acrylate, 6g of hydroxyethyl acrylate, 3g of benzyl methacrylate, 2g of dimethyl diallyl ammonium chloride, and 1g of tetramethyl tetravinylcyclotetrasiloxane in sequence. Stir at 400r / min for 30min to prepare pre-emulsion A.

[0067] S2. Dissolve 3g of ammonium persulfate in 45g of water to prepare initiator solution B;

[0068] S3. Dissolve 0.5g of sodium bisulfite in 10g of water to prepare reducing agent solution C;

[0069] S4. Add 230g of water, 40g of cationic starch, and 0.05g of α-amylase to the reaction vessel, stir well and heat, further raising the temperature to 70℃, and keep it at this temperature while stirring for 20min; after the reaction is completed, add 6g of glacial acetic acid to the reaction vessel to terminate the enzymatic hydrolysis reaction, and keep it at this temperature for 10min.

[0070] S5. Add 16.5g of preemulsion A and 9.6g of initiator solution B to carry out water-soluble polymerization reaction for 20min. Add the remaining preemulsion A and the remaining initiator solution B dropwise to carry out polymerization reaction at 75℃. Add the remaining preemulsion A dropwise for 90min and the remaining initiator solution B dropwise for 100min. After the reaction is completed, keep the reaction at the temperature for about 90min.

[0071] S6. After the heat preservation is completed, cool down to 70℃, add reducing agent solution C dropwise, and finish adding it over about 30 minutes. Keep the reaction at the heat for 20 minutes.

[0072] S7. Cool down to below 40℃, add 0.2g of modified wollastonite and 0.2g of modified bentonite respectively and stir for 30-40 minutes. Then add 1.0g of polyamide polyurea resin LWR-02 (PAPU) and stir for another 30 minutes. Add an appropriate amount of water to adjust the product to a solid content of 30.3% to obtain the paper surface sizing agent.

[0073] Example 2

[0074] S1. Add 50g of water and 3g of cationic emulsifier dodecyl dimethyl benzyl ammonium chloride to a pre-emulsifier. Under stirring conditions, add 60g of styrene, 40g of butyl acrylate, 6g of hydroxyethyl acrylate, 2g of benzyl methacrylate, 1g of methyl 2-benzyl acrylate, 2g of dimethyl diallyl ammonium chloride, and 1g of tetramethyltetravinylcyclotetrasiloxane in sequence. Stir at 400r / min for 30min to prepare pre-emulsion A.

[0075] S2. Dissolve 3g of ammonium persulfate in 45g of water to prepare initiator solution B;

[0076] S3. Dissolve 0.5g of sodium bisulfite in 10g of water to prepare reducing agent solution C;

[0077] S4. Add 230g of water, 40g of cationic starch, and 0.05g of α-amylase to the reaction vessel, stir well and heat, further raising the temperature to 80℃, and keep it at this temperature while stirring for 40min; after the reaction is completed, add 6g of glacial acetic acid to the reaction vessel to terminate the enzymatic hydrolysis reaction, and keep it at this temperature for 10min.

[0078] S5. Add 16.5g of pre-emulsion A, then add 9.6g of initiator solution B to carry out water-soluble polymerization reaction for 20 minutes.

[0079] The remaining pre-emulsion A and the remaining initiator solution B are added dropwise to the reaction to carry out the polymerization reaction. The reaction temperature is 75-83℃. The reaction time for adding the remaining pre-emulsion A is 120 min, and the reaction time for adding the remaining initiator solution B is 100 min. After the reaction is completed, the reaction is kept at the temperature for about 60 min.

[0080] S6. After the heat preservation is completed, cool down to 75℃, add reducing agent solution C dropwise, and finish adding it over about 20-30 minutes. Keep the reaction at the heat for 20 minutes.

[0081] S7. Cool down to below 40℃, add 0.2g of modified wollastonite and 0.2g of modified bentonite respectively and stir for 30min. Then add 1.0g of polyamide polyurea resin LWR-02 (PAPU) and stir for another 40min. Add an appropriate amount of water to adjust the product to a solid content of 30.2%, and the paper surface sizing agent is obtained.

[0082] Example 3

[0083] S1. Add 50g of water and 3g of cationic emulsifier dodecyl dimethyl benzyl ammonium chloride to a pre-emulsifier. Under stirring conditions, add 60g of styrene, 40g of butyl acrylate, 6g of hydroxyethyl acrylate, 3g of benzyl methacrylate, 2g of dimethyl diallyl ammonium chloride, and 1g of tetramethyl tetravinylcyclotetrasiloxane in sequence. Stir at 400r / min for 30min to prepare pre-emulsion A.

[0084] S2. Dissolve 3g of ammonium persulfate in 45g of water to prepare initiator solution B;

[0085] S3. Dissolve 0.5g of sodium bisulfite in 10g of water to prepare reducing agent solution C;

[0086] S4. Add 230g of water, 40g of cationic starch, and 0.05g of α-amylase to the reaction vessel, stir well and heat, further raising the temperature to 80℃, and keep it at this temperature while stirring for 30min; after the reaction is completed, add 6g of glacial acetic acid to the reaction vessel to terminate the enzymatic hydrolysis reaction, and keep it at this temperature for 5min.

[0087] S5. Add 16.5g of preemulsion A and 9.6g of initiator solution B to carry out water-soluble polymerization reaction for 20-30min. Add the remaining preemulsion A and the remaining initiator solution B dropwise to carry out polymerization reaction at 80℃. The remaining preemulsion A is added dropwise over 100min and the remaining initiator solution B is added dropwise over 120min. After the reaction is completed, keep the reaction at the temperature for about 80min.

[0088] S6. After the heat preservation is completed, cool down to 70℃, add reducing agent solution C dropwise, and finish adding it over about 30 minutes. Keep the reaction at the heat for 20 minutes.

[0089] S7. Cool down to below 40℃, add 0.5g of modified wollastonite and 0.5g of modified bentonite respectively and stir for 30-40 minutes. Then add 1.0g of polyamide polyurea resin LWR-02 (PAPU) and stir for another 35 minutes. Add an appropriate amount of water to adjust the product to a solid content of 30.5% to obtain the paper surface sizing agent.

[0090] Example 4

[0091] S1. Add 50g of water, 1.5g of cationic emulsifier dodecyl dimethyl benzyl ammonium chloride, and 1.5g of cationic emulsifier benzyl trimethyl ammonium chloride to a pre-emulsifier. Under stirring conditions, add 60g of styrene, 40g of butyl acrylate, 6g of hydroxyethyl acrylate, 1.5g of benzyl methacrylate, 1.5g of methyl 2-benzyl acrylate, 2g of dimethyl diallyl ammonium chloride, 0.5g of tetramethyltetravinylcyclotetrasiloxane, and 0.5g of divinyltetramethyldisiloxane. Stir at 400r / min for 30min to prepare pre-emulsion A.

[0092] S2. Dissolve 3g of ammonium persulfate in 45g of water to prepare initiator solution B;

[0093] S3. Dissolve 0.5g of sodium bisulfite in 10g of water to prepare reducing agent solution C;

[0094] S4. Add 230g of water, 40g of cationic starch, and 0.05g of α-amylase to the reaction vessel, stir well and heat, further raising the temperature to 80℃, and keep it at this temperature while stirring for 20min; after the reaction is completed, add 6g of glacial acetic acid to the reaction vessel to terminate the enzymatic hydrolysis reaction, and keep it at this temperature for 5min.

[0095] S5. Add 16.5g of pre-emulsion A, then add 9.6g of initiator solution B to carry out water-soluble polymerization reaction for 20 minutes.

[0096] The remaining pre-emulsion A and the remaining initiator solution B were added dropwise to the reaction to carry out the polymerization reaction. The reaction temperature was 83℃. The reaction time for adding the remaining pre-emulsion A was 120 min, and the reaction time for adding the remaining initiator solution B was 100 min. After the reaction was completed, the reaction was kept at the temperature for about 90 min.

[0097] S6. After the heat preservation is completed, cool down to 75℃, add reducing agent solution C dropwise, and finish adding it over about 30 minutes. Keep the reaction at the heat for 20 minutes.

[0098] S7. Cool down to below 40℃, add 0.2g of modified wollastonite and 0.2g of modified bentonite respectively and stir for 30-40 minutes. Then add 2.0g of polyamide polyurea resin LWR-02 (PAPU) and stir for another 30 minutes. Add an appropriate amount of water to adjust the product to a solid content of 30.7%, and you will get the paper surface sizing agent.

[0099] Example 5

[0100] S1. Add 50g of water, 1.5g of cationic emulsifier dodecyl dimethyl benzyl ammonium chloride, and 1.5g of cationic emulsifier benzyl trimethyl ammonium chloride to a pre-emulsifier. Under stirring conditions, add 60g of styrene, 40g of butyl acrylate, 6g of hydroxyethyl acrylate, 1.5g of benzyl methacrylate, 1.5g of benzyl acrylate, 2g of dimethyl diallyl ammonium chloride, 0.5g of tetramethyltetravinylcyclotetrasiloxane, and 0.5g of divinyltetramethyldisiloxane. Stir at 400r / min for 30min to prepare pre-emulsion A.

[0101] S2. Dissolve 3g of ammonium persulfate in 45g of water to prepare initiator solution B;

[0102] S3. Dissolve 0.5g of sodium bisulfite in 10g of water to prepare reducing agent solution C;

[0103] S4. Add 230g of water, 40g of cationic starch, and 0.05g of α-amylase to the reaction vessel, stir well and heat, further raising the temperature to 70-80℃, and keep warm and stirring for 20min; after the reaction is completed, add 6g of glacial acetic acid to the reaction vessel to terminate the enzymatic hydrolysis reaction, and keep warm for 5min.

[0104] S5. Add 16.5g of preemulsion A and 9.6g of initiator solution B to carry out water-soluble polymerization reaction for 20min. Add the remaining preemulsion A and the remaining initiator solution B dropwise to carry out polymerization reaction at 75℃. Add the remaining preemulsion A dropwise for 90min and the remaining initiator solution B dropwise for 130min. After the reaction is completed, keep the reaction at the temperature for about 60min.

[0105] S6. After the heat preservation is completed, cool down to 75℃, add reducing agent solution C dropwise, and finish adding it over about 20 minutes. Keep the reaction at the heat for 30 minutes.

[0106] S7. Cool down to below 40℃, add 0.5g of modified wollastonite and 0.5g of modified bentonite respectively and stir for 40min. Then add 1.0g of polyamide polyurea resin LWR-02 (PAPU) and stir for another 30min. Add an appropriate amount of water to adjust the product to a solid content of 30.6% to obtain the paper surface sizing agent.

[0107] Example 6

[0108] S1. Add 50g of water and 3g of cationic emulsifier dodecyl dimethyl benzyl ammonium chloride to a pre-emulsifier. Under stirring conditions, add 60g of styrene, 40g of butyl acrylate, 6g of hydroxyethyl acrylate, 1g of benzyl methacrylate, 1g of benzyl acrylate, 1g of methyl 2-benzyl acrylate, 2g of dimethyl diallyl ammonium chloride, 0.5g of tetramethyltetravinylcyclotetrasiloxane, and 0.5g of hexamethylhexavinylcyclohexasiloxane. Stir at 400r / min for 30min to prepare pre-emulsion A.

[0109] S2. Dissolve 3g of ammonium persulfate in 45g of water to prepare initiator solution B;

[0110] S3. Dissolve 0.5g of sodium bisulfite in 10g of water to prepare reducing agent solution C;

[0111] S4. Add 230g of water, 40g of cationic starch, and 0.05g of α-amylase to the reaction vessel, stir well and heat, further raising the temperature to 70℃, and keep it at this temperature while stirring for 20min; after the reaction is completed, add 6g of glacial acetic acid to the reaction vessel to terminate the enzymatic hydrolysis reaction, and keep it at this temperature for 5min.

[0112] S5. Add 16.5g of preemulsion A and 9.6g of initiator solution B to carry out water-soluble polymerization reaction for 30min. Add the remaining preemulsion A and the remaining initiator solution B dropwise to carry out polymerization reaction at 75℃. Add the remaining preemulsion A dropwise for 120min and the remaining initiator solution B dropwise for 100min. After the reaction is completed, keep the reaction at the temperature for about 90min.

[0113] S6. After the heat preservation is completed, cool down to 70℃, add reducing agent solution C dropwise, and finish adding it over about 30 minutes. Keep the reaction at the heat for 20 minutes.

[0114] S7. Cool down to below 40℃, add 0.2g of modified wollastonite and 0.2g of modified bentonite respectively and stir for 30min. Then add 1.0g of polyamide polyurea resin LWR-02 (PAPU) and stir for another 40min. Add an appropriate amount of water to adjust the product to a solid content of 30.3%, and the paper surface sizing agent is obtained.

[0115] Experimental Examples

[0116] Formulation for evaluation of paper surface sizing agent application: Add 85g of starch and 0.1g of amylase to 415g of water and stir together in a beaker. Heat to 98℃ in a water bath, stir and keep warm for 30min, then cool to obtain cooked starch. Take 100g of cooked starch, add 0.5g of paper surface sizing agent, stir for 20min, and then coat with No. 2 coating rod at a speed of 15m / min on the unsizing corrugated core paper. Dry in an oven at 90℃ for 40 seconds, and then start testing.

[0117] Using the above method, the paper surface sizing agents in Examples 1-6 of this invention and commercially available paper surface sizing agents are compared respectively. Table 1 shows the application data for evaluating paper surface sizing agents. The Cobb value was tested using the Cobb method according to GB / T540-1989. The surface strength was measured using a J-IGT350 IGT printing adaptor. The lower the Cobb value, the better, and the higher the surface strength, the better.

[0118] Table 1: Evaluation and Application Data of Paper Surface Sizing Agents

[0119]

[0120]

[0121] The data measured in Table 1 show that adding 0.50g of the paper sizing agent of this invention to 100g of oven-dried cooked starch provides excellent water resistance and superior surface strength. Furthermore, compared with the uniform addition amount of currently available commercial sizing agents, the application evaluation shows that the sizing agent of this invention requires less dosage, achieves better results, and exhibits better water resistance than the control. It is also significantly better than general commercially available sizing agents. The commercially available sizing agent used in this embodiment is a cationic sizing agent from Solis Chemicals Co., Ltd., with a solid content of 31.2%. In summary, the paper sizing agent product of this invention has the following advantages:

[0122] 1) The product manufacturing process is relatively simple, green and environmentally friendly, and produces no waste.

[0123] 2) Introduce a variety of functional monomers, including hydrophobic monomers, cationic monomers and modified monomers, and combine them with monomers such as styrene, butyl acrylate and hydroxyethyl acrylate to graft copolymerize and modify cationic starch to obtain a multifunctional polymer copolymer surface agent. After film formation, it can effectively crosslink and bind to the surface of paper fibers and form a multidimensional spatial hydrophobic network structure on the paper surface, thereby effectively improving the water resistance and strength of paper.

[0124] 3) By controlling the mass ratio of the hydrophobic monomer benzyl methacrylate to the modified monomer tetramethyltetravinylcyclotetrasiloxane to 1.0-3.0:1, and combining a certain number of cationic monomers, the rigid main chain of the polymer can have more hydrophobic cationic grouped branches, which can enable the surface adhesive to achieve good water and moisture resistance under low dosage conditions.

[0125] 4) Introduce modified monomers containing siloxane groups: one or more of divinyltetramethyldisiloxane, tetramethyltetravinylcyclotetrasiloxane, and hexamethylhexavinylcyclohexasiloxane. Utilizing the cross-linking hydrophobic effect of organosilicon monomers, combined with the hydrophobic ester groups and hydroxyl groups contained in the original polymer, a strong water-resistant property is formed by the layering of multiple hydrophobic groups, further improving the overall water resistance of the paper.

[0126] 4) The introduction of 600-mesh fibrous papermaking-grade wollastonite modified with silane coupling agent KH-550 and dodecylamine, and bentonite modified by sulfuric acid acidification, can make the surface sizing agent polymer firmly adsorbed on the paper fiber surface and form a high-hardness, honeycomb-like dense protective film structure on the paper surface. This comprehensively improves the water resistance and hardness of the original paper protective film, thereby significantly improving the film-forming water resistance of the surface sizing agent and the surface strength of the paper after film formation.

[0127] 5) When the sizing agent of this invention is added to an application evaluation system containing starch, it can enable more effective cross-linking between the cationic sizing agent, the starch system, and the paper fibers, making the original sizing agent film more uniform. In addition, the polyamide polyurea resin (PAPU) contained in the sizing agent can enable the original sizing agent to quickly form a film and mature, and be more firmly adsorbed onto the paper surface. Combined with the active hydroxyl groups, polyamino and other multifunctional active groups contained therein, the sizing agent is easier to cross-link and cure, thereby further improving the water resistance and overall stability of the paper.

[0128] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A paper surface size, characterized in that, The cationic monomer, the hydrophobic monomer, the modified monomer, cationic starch, styrene, butyl acrylate and hydroxyethyl acrylate; The cationic monomer, the hydrophobic monomer, the modified monomer, cationic starch, styrene, butyl acrylate and hydroxyethyl acrylate; The initiator and the reducing agent are further included; The modified wollastonite is 0.2-0.5 parts, the modified bentonite is 0.2-0.5 parts, and the polyamide polyurea resin is 1.0-2.0 parts; The modified wollastonite is 0.2-0.5 parts, the modified bentonite is 0.2-0.5 parts, and the polyamide polyurea resin is 1.0-2.0 parts; The modified wollastonite is 0.2-0.5 parts, the modified bentonite is 0.2-0.5 parts, and the polyamide polyurea resin is 1.0-2.0 parts; The cationic monomer is selected from one or both of dimethyldiallylammonium chloride and dimethylaminopropyl methacrylamide; The hydrophobic monomer is selected from one or more of benzyl acrylate, benzyl methacrylate and 2-benzyl methyl acrylate; The modified monomer is selected from one or more of divinyltetramethyl disiloxane, tetramethyltetraethenyl cyclosiloxane and hexamethylhexaethenyl cyclohexasiloxane; The cationic starch is cationic modified tapioca starch; The a-amylase is 0.05-0.10 parts, the cationic emulsifier is 3-5 parts, and the glacial acetic acid is 6-10 parts; The preparation method of the paper surface sizing agent comprises the following steps: S1, preparing a pre-emulsion A: adding water and a cationic emulsifier into an emulsifying kettle, stirring uniformly, and then adding styrene, butyl acrylate, hydroxyethyl acrylate, a hydrophobic monomer, a cationic monomer and a modified monomer in sequence to prepare the pre-emulsion A; S2, preparing an initiator solution B: dissolving the initiator in water to prepare the initiator solution B; S3, preparing a reducing agent solution C: dissolving the reducing agent in water to prepare the reducing agent solution C; S4, adding water, cationic starch and a-amylase into a reaction kettle, stirring and heating to 70-80 DEG C, and then keeping the temperature and stirring for 20-40 min, and then adding 6-10 parts of glacial acetic acid into the reaction kettle to terminate the enzymatic reaction and keeping the temperature for 5-10 min; S5, adding part of the pre-emulsion A and part of the initiator solution B to carry out water-soluble polymerization reaction, and then adding the remaining pre-emulsion A and the remaining initiator solution B to carry out emulsion polymerization reaction, wherein the reaction temperature is 75-83 DEG C, the remaining pre-emulsion A is added dropwise for 90-120 min, and the remaining initiator solution B is added dropwise for 100-130 min, and then keeping the temperature for 60-90 min after the reaction is completed; S6, after keeping the temperature, cooling to 70-75 DEG C, and then adding the reducing agent solution C dropwise, and the adding is completed in 20-30 min, and then keeping the temperature for 20-30 min. S7, after adding modified wollastonite and modified bentonite stirring, then adding polyamide polyurea resin further stirring, adding appropriate amount of water to adjust the product solid content, the final product is obtained.

2. The paper surface sizing agent according to claim 1, characterized in that, The a-amylase is a liquid mesophilic a-amylase with an enzyme activity of 4000 U / g. The cationic emulsifier is selected from one or both of dodecyl dimethyl benzyl ammonium chloride and benzyl trimethyl ammonium chloride.

3. The paper surface size of claim 1 wherein, The initiator is selected from one or more of ammonium persulfate, potassium persulfate, and sodium persulfate; and the reducing agent is selected from one or more of sodium bisulfite, potassium bisulfite, and ammonium bisulfite.

4. A method for preparing the paper surface sizing agent of claim 1, comprising the following steps: S1, preparing a pre-emulsion A: adding water and a cationic emulsifier to an emulsification kettle, stirring uniformly, and then sequentially adding styrene, butyl acrylate, hydroxyethyl acrylate, a hydrophobic monomer, a cationic monomer, and a modified monomer to prepare the pre-emulsion A; S2, preparing an initiator solution B: dissolving an initiator in water to prepare the initiator solution B; S3, preparing a reducing agent solution C: dissolving a reducing agent in water to prepare the reducing agent solution C; S4, adding water, cationic starch, and a-amylase to a reaction kettle, stirring and heating to 70-80°C, and maintaining the temperature and stirring for 20-40 min to complete the reaction, then adding 6-10 parts of glacial acetic acid to the reaction kettle to terminate the enzyme reaction, and maintaining the temperature for 5-10 min; S5, adding part of the pre-emulsion A and part of the initiator solution B to perform a water-soluble polymerization reaction; adding the remaining pre-emulsion A and the remaining initiator solution B to perform an emulsion polymerization reaction, with a reaction temperature of 75-83°C, a remaining pre-emulsion A dropwise addition reaction time of 90-120 min, and a remaining initiator solution B dropwise addition reaction time of 100-130 min; after the reaction is completed, maintaining the temperature for 60-90 min; S6, after the temperature maintenance is completed, cooling to 70-75°C, and dropwise adding the reducing agent solution C, which is completed in 20-30 min, and maintaining the temperature for 20-30 min; S7, after adding modified wollastonite and modified bentonite stirring, then adding polyamide polyurea resin further stirring, adding appropriate amount of water to adjust the product solid content, the final product is obtained.

5. The paper surface sizing agent preparation method according to claim 4, characterized by, The solid content of the paper surface sizing agent is 29%-31%.

Images