Gelatin-based paper sizing agent based on hydrogen bonding and method for preparing the same

Abstract

The scheme discloses a gelatin-based paper sizing agent based on hydrogen bonding and a preparation method thereof, and leather solid waste is used to extract gelatin as raw material to prepare gelatin aqueous solution; then a monomer containing a hydrophilic group is introduced to build intermolecular hydrogen bond with the gelatin to obtain modified gelatin emulsion; then an acrylic ester-based toughening elastomer emulsion is prepared; finally, the finished sizing agent is obtained by compounding and homogenizing according to the proportion. The present application relies on hydrogen bond physical modification to replace traditional chemical grafting and crosslinking, breaks through the limitation of the number of gelatin amino groups, solves the problems of easy gelation of pure gelatin at room temperature and unstable storage, and greatly improves the water resistance and tensile performance of the paper by compounding the soft and hard segments. The raw material is tannery waste, which is green, biodegradable and low in production cost. The whole process is simple and controllable, and can be used for paper pulp and surface sizing in industrialized large scale.

Description

Technical Field

[0001] This invention relates to the field of papermaking additives technology, and in particular to a gelatin-based papermaking sizing agent based on hydrogen bonding and its preparation method. Background Technology

[0003] Traditional gelatin modification often employs chemical cross-linking and grafting methods, relying on groups such as -NH2 on the gelatin chain. Due to the limited number of groups, there are limitations in modification. Traditional paper sizing agents generally suffer from high cost, easy pollution, poor water resistance after sizing, and insufficient physical and mechanical properties.

[0004] Existing biomass sizing agents have low gelatin utilization rates and are prone to gelling at room temperature, making it difficult to maintain liquid stability and thus unsuitable for the needs of industrial paper production. There is an urgent need for a low-cost, environmentally friendly, modified, and highly efficient gelatin-based sizing agent and its preparation method. Summary of the Invention

[0005] The present invention aims to provide a gelatin-based paper sizing agent based on hydrogen bonding and its preparation method, in order to solve the technical problems of existing gelatin chemical modification having limited number of functional groups, high cost and pollution of traditional paper sizing agents, poor water resistance and mechanical properties of paper, and ordinary biomass gelatin sizing agents being prone to gelling at room temperature, having poor liquid stability, and being difficult to apply industrially.

[0006] The preparation method of a gelatin-based paper sizing agent based on hydrogen bonding in this scheme includes the following steps: Step 1: Preparation of gelatin solution: Weigh 1~10g of gelatin, add 20mL of deionized water, let stand for 10~60min to fully swell, place in a constant temperature water bath at 30~60℃ and stir until completely dissolved to obtain gelatin solution; Step 2: Preparation of hydrogen-bonded modified gelatin emulsion: Add 1-5g of monomer A, which can form hydrogen bonds with gelatin, and 0.1%-0.5% of initiator A by mass of monomer A to the gelatin solution, and react for 0.5-5h to obtain hydrogen-bonded modified gelatin emulsion; monomer A is any one of acrylic acid, methacrylic acid, acrylamide, methacrylamide, and N-hydroxymethylacrylamide; Step 3: Preparation of toughened elastomer emulsion: Dissolve 1%~5% of the total mass of monomer B emulsifier in water, adjust the pH to 7~10, heat to below 85℃, add 1%~5% of the total mass of monomer B initiator B aqueous solution and part of monomer B, react at 65~90℃, after obvious exothermic reaction, control the temperature at 65~90℃, slowly add the remaining monomer B dropwise over 1~3 hours; raise the temperature to 80~95℃ and react for 1.0~3 hours, cool and adjust the pH to 8~9 to obtain toughened elastomer emulsion; monomer B is any one of ethyl acrylate, butyl acrylate, n-octyl acrylate, and isooctyl acrylate; emulsifier is one or more of sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, and Tween 20; initiator B is any one of ammonium persulfate, potassium persulfate, and azobisisobutyramidine hydrochloride; Step 4: Compounding to obtain the finished product: Mix the hydrogen bond modified gelatin emulsion and the toughened elastomer emulsion at a mass ratio of monomer A to monomer B of 3:1 to 1:3, and then rapidly stir and ultrasonically defoam to obtain a gelatin-based paper sizing agent based on hydrogen bonding.

[0007] Furthermore, the initiator A is a photoinitiator, a thermal initiator, or a redox initiator; the initiator B is any one of ammonium persulfate, potassium persulfate, or azobisisobutyramidine hydrochloride.

[0008] Furthermore, the emulsifier is one or more of sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, and Tween 20.

[0009] Furthermore, the gelatin mentioned in step one is gelatin extracted from waste leather scraps.

[0010] Furthermore, in step two, monomer A is selected as methacrylic acid, and the amount of initiator A is 0.1% of the mass of monomer A; the ultraviolet light initiation reaction time is 60 min, and the thermal initiation isothermal reaction time is 3-4 h.

[0011] Furthermore, in step three, the amount of emulsifier used is 3% of the total mass of monomer B, the amount of initiator B used is 1% of the total mass of monomer B, and the polymerization reaction is controlled at a constant temperature of 80 ℃.

[0012] Furthermore, in step four, the mass ratio of monomer A to monomer B is 1.5:1.

[0013] Furthermore, in step one, the gelatin swelling temperature is 35–50 °C, and the swelling and standing time is 20–40 min.

[0014] The working principle and beneficial effects of this scheme are as follows: 1. Modification and innovation: Based on hydrogen bonding, gelatin is physically modified to avoid the limitations of chemical modification groups. Monomers and gelatin chains form a large number of tight hydrogen bonds, which increases the hydrophobicity of gelatin and inhibits entanglement and gelation at room temperature, thus maintaining the stability of the emulsion in a liquid state. 2. Excellent performance: The combination of hard segment gelatin and soft segment elastomer significantly improves the paper's water resistance, tensile strength, and compressive strength, making it suitable for various paper production needs; 3. Environmentally friendly and low-cost: The gelatin is extracted from waste leather scraps, which reduces costs and solid waste pollution. The adhesive is easily biodegradable and has no environmental hazards. 4. Industrialization adaptability: The process is simple, the parameters are controllable, and the gelatin utilization rate is high (the mass ratio of gelatin to monomer can reach 1:1), making it suitable for large-scale industrial production. Detailed Implementation

[0015] The following detailed explanation illustrates the specific implementation methods: Example 1 Step 1: Gelatin solution preparation: Take 5 g of waste leather scraps to extract gelatin, add 20 mL of deionized water and let stand for 30 min to fully swell, then stir in a 45 ℃ constant temperature water bath until completely dissolved; Step 2: Hydrogen bond modified gelatin emulsion: Add 3 g of methacrylic acid and 0.003 g of thermal initiator to the gelatin solution, and stir at 45 ℃ for 3.5 h to obtain hydrogen bond modified gelatin emulsion; Step 3: Preparation of toughened elastomer emulsion: Take 2 g of butyl acrylate monomer, add 0.06 g of sodium dodecyl sulfate emulsifier, add water and stir to dissolve, adjust the pH of the system to 8, and heat to 80 ℃; add 0.02 g of ammonium persulfate aqueous solution and 0.5 g of butyl acrylate prepolymer; after the system exothermics, stabilize at 80 ℃ and add the remaining 1.5 g of butyl acrylate dropwise at a uniform rate for 2 h; after the dropwise addition is completed, heat to 85 ℃ and keep the reaction at this temperature for 2 h, then cool naturally and adjust the pH to 8.5 to obtain the elastomer emulsion; Step 4: Compounding and molding: Mix the two emulsions according to the mass ratio of monomer A: monomer B of 1.5:1, homogenize at high speed for 10 min, and ultrasonically defoam for 5 min to obtain the finished gelatin-based paper sizing agent.

[0016] Performance testing: When ordinary writing paper is sizing with the sizing agent of this embodiment, the water penetration resistance time of the paper is increased by 80% and the tensile strength of the paper is increased by 35%; after 30 days of sealed storage at room temperature, there is no delamination or gel clumping.

[0017] Example 2 Step 1: Preparation of gelatin solution: Take 2 g of waste leather gelatin, add 20 mL of deionized water, let stand for 15 min to swell, and then stir and dissolve in a 35 ℃ water bath. Step 2: Hydrogen bond modified gelatin emulsion: Add 1 g acrylamide and 0.005 g photoinitiator, and react under ultraviolet light for 60 min to obtain the modified emulsion; Step 3: Toughening elastomer emulsion: Weigh 3 g of ethyl acrylate, add 0.09 g of Tween 20, adjust pH to 9, and heat to 80 ℃; add 0.03 g of potassium persulfate and 0.8 g of ethyl acrylate for pre-reaction, after exothermic reaction, maintain the temperature at 80 ℃ for 1.5 h, and add the remaining monomers dropwise; heat to 88 ℃ and hold for 1.5 h, then cool and adjust pH to 8; Step 4: Compound molding: Mix monomer A and monomer B in a mass ratio of 1:2 to form an emulsion, then homogenize and stir + use ultrasound to remove bubbles to obtain the finished sizing agent.

[0018] Example 3 Step 1: Preparation of gelatin solution: Take 8 g of waste leather gelatin, add 20 mL of deionized water and let stand for 50 min to swell, then dissolve in a 55 ℃ water bath; Step 2: Hydrogen bond modified gelatin emulsion: Add 4 g N-hydroxymethylacrylamide and 0.012 g redox initiator, and react at a constant temperature of 50 ℃ with stirring for 4 h. Step 3: Toughening elastomer emulsion: 2 g isooctyl acrylate, add 0.05 g sodium dodecylbenzenesulfonate, adjust pH to 7.5, add 0.05 g azobisisobutyramidine hydrochloride and 0.6 g monomer at 80 ℃; after exothermic reaction, add the remaining monomer dropwise for 2.5 h, keep warm at 90 ℃ for 1.8 h, cool and adjust pH to 8.2; Step 4: Compound molding: Mix the two emulsions, monomer A: monomer B = 2:1, homogenize, and ultrasonically defoam to obtain the finished sizing agent.

[0019] Basic properties of blank base paper: 70 g / m²; Unsized writing base paper: Water penetration time 28s, dry tensile strength 22.5 N / 15mm, 60s Cobb water absorption 68.2 g / m² Experimental materials: Gelatin extracted from tannery waste, methacrylic acid / acrylamide / N-hydroxymethylacrylamide, ethyl acrylate / butyl acrylate / isooctyl acrylate, sodium lauryl sulfate, Tween 20, sodium dodecylbenzene sulfonate, ammonium persulfate, potassium persulfate, azobisisobutyramidine hydrochloride, various initiators, deionized water. Testing equipment: Constant temperature water bath, homogenizer, ultrasonic cleaner / defoamer, paper tensile strength tester, paper water resistance tester, electronic balance, pH meter, high-speed centrifuge, constant temperature sealed storage box. Test sample: 70 g / m² ordinary writing paper.

[0020] Comparison of test data from blank base paper, traditional chemical cross-linked gelatin sizing agents, and three groups of hydrogen-bonded modified gelatin sizing agents with different ratios shows that Example 1 (monomer A to monomer B mass ratio of 1.5:1) exhibits the best overall performance. After sizing, the paper's water penetration time is increased by 80%, tensile strength by 35%, and the 60s Cobb water absorption value is only 31.5 g / m². The emulsion does not separate or gel after 30 days of sealed storage at room temperature. Compared to glutaraldehyde chemical cross-linked modified products, the hydrogen-bonded modified system of this invention significantly improves storage stability, increases raw material utilization, and accelerates biodegradation. Furthermore, the paper's water resistance and mechanical strengthening effects are nearly doubled. Single-factor experiments confirm that a monomer A to B ratio of 1.5:1 and gelatin swelling at 45℃ are the optimal process conditions. Utilizing leather waste gelatin can reduce raw material costs by nearly half. The finished product is formaldehyde-free, free of heavy metals, and readily biodegradable, balancing performance, storage stability, production costs, and environmental friendliness.

[0021] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for preparing a gelatin-based paper sizing agent based on hydrogen bonding, characterized in that: Includes the following steps: Step 1: Preparation of gelatin solution: Weigh 1~10g of gelatin, add 20mL of deionized water, let stand for 10~60min to fully swell, place in a constant temperature water bath at 30~60℃ and stir until completely dissolved to obtain gelatin solution; Step 2: Preparation of hydrogen-bonded modified gelatin emulsion: Add 1-5g of monomer A, which can form hydrogen bonds with gelatin, and 0.1%-0.5% of initiator A by mass of monomer A to the gelatin solution, and react for 0.5-5h to obtain hydrogen-bonded modified gelatin emulsion; monomer A is any one of acrylic acid, methacrylic acid, acrylamide, methacrylamide, and N-hydroxymethylacrylamide; Step 3: Preparation of toughened elastomer emulsion: Dissolve 1%~5% of the total mass of monomer B emulsifier in water, adjust the pH to 7~10, heat to below 85℃, add 1%~5% of the total mass of monomer B initiator B aqueous solution and part of monomer B, react at 65~90℃, after obvious exothermic reaction, control the temperature at 65~90℃, slowly add the remaining monomer B dropwise over 1~3 hours; raise the temperature to 80~95℃ and react for 1.0~3 hours, cool and adjust the pH to 8~9 to obtain toughened elastomer emulsion; monomer B is any one of ethyl acrylate, butyl acrylate, n-octyl acrylate, and isooctyl acrylate; emulsifier is one or more of sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, and Tween 20; initiator B is any one of ammonium persulfate, potassium persulfate, and azobisisobutyramidine hydrochloride; Step 4: Compounding to obtain the finished product: Mix the hydrogen bond modified gelatin emulsion and the toughened elastomer emulsion at a mass ratio of monomer A to monomer B of 3:1 to 1:3, and then rapidly stir and ultrasonically defoam to obtain a gelatin-based paper sizing agent based on hydrogen bonding.

2. The method for preparing a gelatin-based paper sizing agent based on hydrogen bonding according to claim 1, characterized in that: The initiator A is a photoinitiator, a thermal initiator, or a redox initiator; the initiator B is any one of ammonium persulfate, potassium persulfate, or azobisisobutyramidine hydrochloride.

3. The method for preparing a gelatin-based paper sizing agent based on hydrogen bonding according to claim 2, characterized in that: The emulsifier is one or more of sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, and Tween 20.

4. The method for preparing a gelatin-based paper sizing agent based on hydrogen bonding according to claim 3, characterized in that: The gelatin mentioned in step one is gelatin extracted from waste leather scraps.

5. A method for preparing a gelatin-based paper sizing agent based on hydrogen bonding according to claim 4, characterized in that: In step two, monomer A is methacrylic acid, and the amount of initiator A is 0.1% of the mass of monomer A; the ultraviolet light initiation reaction time is 60 min, and the thermal initiation isothermal reaction time is 3-4 h.

6. A method for preparing a gelatin-based paper sizing agent based on hydrogen bonding according to claim 5, characterized in that: In step three, the amount of emulsifier used is 3% of the total mass of monomer B, the amount of initiator B used is 1% of the total mass of monomer B, and the polymerization reaction is controlled at a constant temperature of 80 ℃.

7. A method for preparing a gelatin-based paper sizing agent based on hydrogen bonding according to claim 6, characterized in that: In step four, the mass ratio of monomer A to monomer B is 1.5:

1.

8. A method for preparing a gelatin-based paper sizing agent based on hydrogen bonding according to claim 7, characterized in that: In step one, the gelatin swelling temperature is 35–50 °C, and the swelling and standing time is 20–40 min.

9. A gelatin-based paper sizing agent based on hydrogen bonding according to claim 8, characterized in that: It is prepared by the preparation method described in any one of claims 1 to 8.

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