Preparation method of starch adhesive for corrugated paper

Abstract

The present invention belongs to the technical field of adhesive preparation, and specifically relates to a method for preparing a starch adhesive for corrugated paper. The method for preparing the starch adhesive for corrugated paper comprises the following steps: oxidizing starch to prepare a first reactant; adding water to the first reactant and mixing, then adding sodium hydroxide solution to continue the reaction for 50-55 minutes, and finally adding phosphorus oxychloride and dialdehyde starch to react at 38-40°C for 2.3-2.5 hours to prepare a second reactant; adding furfural, meta-cresol and salicylic acid to the second reactant for copolymerization, and finally adding polyhydroxyethyl methacrylate and vinyl acetate acrylate copolymer to stir evenly to prepare a starch adhesive for corrugated paper. The starch adhesive for corrugated paper prepared by the method has excellent bonding strength and stability.

Description

Technical Field

[0001] The invention belongs to the technical field of adhesive preparation, and specifically relates to a method for preparing a starch adhesive for corrugated paper. Background Art

[0002] Existing corrugated paper is composed of upper flat paper, lower flat paper and corrugated paper bonded between the upper and lower flat papers. This single piece of corrugated paper can be bonded to each other to form a double or triple structure of corrugated paper. Corrugated paper has the advantages of light weight, compression resistance, puncture resistance, tear resistance, and easy processing and forming, which makes the use of corrugated paper more and more extensive. When manufacturing corrugated paper, adhesives are needed to bond the corrugated medium and the paper surface. Adhesives play an important connecting role in the processing and forming process of corrugated paper, and have a close impact on the physical indicators of the finished paperboard performance such as appearance flatness, burst resistance, folding resistance and puncture strength. Therefore, the preparation of excellent adhesives has always been an important research topic in the production of corrugated paper.

[0003] Commonly used adhesives include water glass, starch adhesives, synthetic polymer adhesives and mixtures thereof, among which starch adhesives are the most commonly used. Existing starch adhesives have high water content, which causes high moisture content of corrugated paper during use, resulting in slow drying speed. In addition, since moisture easily penetrates into the paper during the drying process, the initial moisture content of the corrugated paper is high, and the bonding strength of the starch adhesive is reduced, which limits the use of the starch adhesive. Therefore, it is necessary to explore a new type of starch adhesive for corrugated paper. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing a starch adhesive for corrugated paper. The starch adhesive prepared by the method has strong bonding force.

[0005] The preparation method of the starch adhesive for corrugated paper of the present invention comprises the following steps:

[0006] (1) adding water to starch and stirring to form a paste, then adding sulfuric acid solution and potassium permanganate solution and mixing, oxidizing at 45-48° C. for 2.8-3 hours, and cooling to room temperature to prepare a first reactant;

[0007] (2) adding water to the first reactant under stirring and mixing, then adding sodium hydroxide solution and continuing the reaction for 50-55 minutes, and finally adding phosphorus oxychloride and dialdehyde starch and reacting at 38-40° C. for 2.3-2.5 hours to prepare a second reactant;

[0008] (3) Furfural, m-cresol and salicylic acid are added to the second reactant prepared in step (2) for copolymerization, and finally polyhydroxyethyl methacrylate and vinyl acetate acrylate copolymer are added and stirred evenly to prepare a starch adhesive for corrugated paper.

[0009] in:

[0010] The starch described in step (1) is corn starch.

[0011] The mass ratio of starch to water in step (1) is 1:1.5-1.7.

[0012] The concentration of the sulfuric acid solution in step (1) is 2.5 mol / L, and the mass ratio of the volume of the sulfuric acid solution to the starch is 1:9.6, in units of mL / g.

[0013] The mass concentration of the potassium permanganate solution in step (1) is 3.3%, and the mass ratio of the volume of the potassium permanganate solution to the starch is 1:2, in units of mL / g.

[0014] The mass ratio of the water in step (1) to the water in step (2) is 1:1.4-1.6.

[0015] The mass concentration of the sodium hydroxide solution in step (2) is 25%, and the volume ratio of the sodium hydroxide solution to the starch is 11:25, in units of mL / g.

[0016] The mass of phosphorus oxychloride in step (2) accounts for 0.003-0.005% of the mass of starch in step (1).

[0017] The mass of the dialdehyde starch in step (2) accounts for 0.55-0.75% of the mass of the starch in step (1).

[0018] The mass of furfural in step (3) accounts for 0.4-0.5% of the mass of starch in step (1), and the mass of m-cresol accounts for 0.2-0.3% of the mass of starch in step (1).

[0019] The mass of salicylic acid in step (3) accounts for 1.2% of the mass of starch in step (1).

[0020] In step (3), the copolymerization reaction temperature is 65-67° C., and the copolymerization reaction time is 2 h.

[0021] The mass of the polyhydroxyethyl methacrylate in step (3) accounts for 1.0-1.2% of the mass of the starch in step (1), and the mass of the vinyl acetate acrylate copolymer accounts for 0.4-0.6% of the mass of the starch in step (1).

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The preparation method of the starch adhesive for corrugated paper of the present invention comprises the following steps: firstly, potassium permanganate is used to oxidize starch to oxidize part of the hydroxyl groups in the starch molecules into carboxyl groups, carbonyl groups or aldehyde groups, thereby improving the adhesion to paper fibers; and sulfuric acid is used to acid-modify the starch to improve the stability, fluidity and initial adhesion of the starch; then, sodium hydroxide is added as a gelatinizer to improve the hydrophilicity, fluidity and anti-aging ability of the starch adhesive; a mixture of phosphorus oxychloride and dialdehyde starch is used as a cross-linking agent, and phosphorus oxychloride reacts with the hydroxyl groups in the starch molecules to generate distarch phosphate, thereby bridging the starch molecules through phosphate ester bonds to form a multidimensional spatial network structure, thereby improving the shear resistance of the starch adhesive; however, the cross-linking between phosphorus oxychloride and starch occurs on the surface of starch particles; therefore, dialdehyde starch is compounded, and the aldehyde groups in the dialdehyde starch and the highly active hydroxyl groups in the starch form hemiacetal groups and hydrogen bond networks, thereby achieving intramolecular and intermolecular cross-linking, thereby improving the mechanical properties and water resistance of the starch adhesive. In addition, furfural and m-cresol are added in an acidic environment, and furfural and m-cresol respectively undergo copolymerization or polycondensation reaction with the carbonyl group and aldehyde group with poor bonding strength generated after the oxidation reaction, thereby further improving the bonding strength of the prepared starch adhesive.

[0024] (2) In the method for preparing the starch adhesive for corrugated paper described in the present invention, polyhydroxyethyl methacrylate and vinyl acetate acrylate copolymer are further added to the prepared starch adhesive, wherein the addition of polyhydroxyethyl methacrylate can reduce the combination of free hydroxyl groups in starch molecules with water molecules, thereby reducing the water absorption of the starch adhesive, while the vinyl acetate in the vinyl acetate acrylate copolymer can reduce the penetration of water molecules and improve the water resistance of the starch adhesive. In addition, the flexibility of the vinyl acetate acrylate copolymer can further improve the mechanical properties of the starch adhesive.

[0025] (3) The starch adhesive for corrugated paper prepared by this method has excellent bonding strength and stability. DETAILED DESCRIPTION

[0026] The present invention is further described below with reference to the embodiments.

[0027] Example 1

[0028] The preparation method of the starch adhesive for corrugated paper described in this embodiment 1 is composed of the following steps:

[0029] (1) adding water to starch and stirring to form a paste, then adding sulfuric acid solution and potassium permanganate solution and mixing, oxidizing at 47° C. for 2.9 hours, and cooling to room temperature to prepare a first reactant;

[0030] (2) adding water to the first reactant under stirring and mixing, then adding sodium hydroxide solution and continuing the reaction for 53 minutes, and finally adding phosphorus oxychloride and dialdehyde starch and reacting at 39° C. for 2.4 hours to prepare a second reactant;

[0031] (3) Furfural, m-cresol and salicylic acid are added to the second reactant prepared in step (2) for copolymerization, and finally polyhydroxyethyl methacrylate and vinyl acetate acrylate copolymer are added and stirred evenly to prepare a starch adhesive for corrugated paper.

[0032] in:

[0033] The starch described in step (1) is corn starch.

[0034] The mass ratio of starch to water in step (1) is 1:1.6.

[0035] The concentration of the sulfuric acid solution in step (1) is 2.5 mol / L, and the mass ratio of the volume of the sulfuric acid solution to the starch is 1:9.6, in units of mL / g.

[0036] The mass concentration of the potassium permanganate solution in step (1) is 3.3%, and the mass ratio of the volume of the potassium permanganate solution to the starch is 1:2, in units of mL / g.

[0037] The mass ratio of the water in step (1) to the water in step (2) is 1:1.5.

[0038] The concentration of the sodium hydroxide solution in step (2) is 25%, and the volume ratio of the sodium hydroxide solution to the starch mass is 11:25, in units of mL / g.

[0039] The mass of phosphorus oxychloride in step (2) accounts for 0.004% of the mass of starch in step (1).

[0040] The mass of the dialdehyde starch in step (2) accounts for 0.65% of the mass of the starch in step (1).

[0041] The mass of furfural in step (3) accounts for 0.45% of the mass of starch in step (1), and the mass of m-cresol accounts for 0.25% of the mass of starch in step (1).

[0042] The mass of salicylic acid in step (3) accounts for 1.2% of the mass of starch in step (1).

[0043] In step (3), the copolymerization reaction temperature is 66° C. and the copolymerization reaction time is 2 h.

[0044] The mass of polyhydroxyethyl methacrylate in step (3) accounts for 1.1% of the mass of starch in step (1), and the mass of vinyl acetate acrylate copolymer accounts for 0.5% of the mass of starch in step (1).

[0045] Example 2

[0046] The preparation method of the starch adhesive for corrugated paper described in this embodiment 2 is composed of the following steps:

[0047] (1) adding water to starch and stirring to form a paste, then adding sulfuric acid solution and potassium permanganate solution and mixing, oxidizing at 45° C. for 3 h, and cooling to room temperature to prepare a first reactant;

[0048] (2) adding water to the first reactant under stirring and mixing, then adding sodium hydroxide solution and continuing the reaction for 50 minutes, and finally adding phosphorus oxychloride and dialdehyde starch and reacting at 38° C. for 2.5 hours to prepare a second reactant;

[0049] (3) Furfural, m-cresol and salicylic acid are added to the second reactant prepared in step (2) for copolymerization, and finally polyhydroxyethyl methacrylate and vinyl acetate acrylate copolymer are added and stirred evenly to prepare a starch adhesive for corrugated paper.

[0050] in:

[0051] The starch described in step (1) is corn starch.

[0052] The mass ratio of starch to water in step (1) is 1:1.7.

[0053] The concentration of the sulfuric acid solution in step (1) is 2.5 mol / L, and the mass ratio of the volume of the sulfuric acid solution to the starch is 1:9.6, in units of mL / g.

[0054] The mass concentration of the potassium permanganate solution in step (1) is 3.3%, and the mass ratio of the volume of the potassium permanganate solution to the starch is 1:2, in units of mL / g.

[0055] The mass ratio of the water in step (1) to the water in step (2) is 1:1.6.

[0056] The concentration of the sodium hydroxide solution in step (2) is 25%, and the volume ratio of the sodium hydroxide solution to the starch mass is 11:25, in units of mL / g.

[0057] The mass of phosphorus oxychloride in step (2) accounts for 0.005% of the mass of starch in step (1).

[0058] The mass of the dialdehyde starch in step (2) accounts for 0.55% of the mass of the starch in step (1).

[0059] The mass of furfural in step (3) accounts for 0.5% of the mass of starch in step (1), and the mass of m-cresol accounts for 0.2% of the mass of starch in step (1).

[0060] The mass of salicylic acid in step (3) accounts for 1.2% of the mass of starch in step (1).

[0061] In step (3), the copolymerization reaction temperature is 65° C. and the copolymerization reaction time is 2 h.

[0062] The mass of polyhydroxyethyl methacrylate in step (3) accounts for 1.0% of the mass of starch in step (1), and the mass of vinyl acetate acrylate copolymer accounts for 0.6% of the mass of starch in step (1).

[0063] Example 3

[0064] The preparation method of the starch adhesive for corrugated paper described in this embodiment 3 is composed of the following steps:

[0065] (1) adding water to starch and stirring to form a paste, then adding sulfuric acid solution and potassium permanganate solution and mixing, oxidizing at 48° C. for 2.8 h, and cooling to room temperature to prepare a first reactant;

[0066] (2) adding water to the first reactant under stirring and mixing, then adding sodium hydroxide solution and continuing the reaction for 55 minutes, and finally adding phosphorus oxychloride and dialdehyde starch and reacting at 40° C. for 2.3 hours to prepare a second reactant;

[0067] (3) Furfural, m-cresol and salicylic acid are added to the second reactant prepared in step (2) for copolymerization, and finally polyhydroxyethyl methacrylate and vinyl acetate acrylate copolymer are added and stirred evenly to prepare a starch adhesive for corrugated paper.

[0068] in:

[0069] The starch described in step (1) is corn starch.

[0070] The mass ratio of starch to water in step (1) is 1:1.5.

[0071] The concentration of the sulfuric acid solution in step (1) is 2.5 mol / L, and the mass ratio of the volume of the sulfuric acid solution to the starch is 1:9.6, in units of mL / g.

[0072] The mass concentration of the potassium permanganate solution in step (1) is 3.3%, and the mass ratio of the volume of the potassium permanganate solution to the starch is 1:2, in units of mL / g.

[0073] The mass ratio of the water in step (1) to the water in step (2) is 1:1.4.

[0074] The concentration of the sodium hydroxide solution in step (2) is 25%, and the volume ratio of the sodium hydroxide solution to the starch mass is 11:25, in units of mL / g.

[0075] The mass of phosphorus oxychloride in step (2) accounts for 0.003% of the mass of starch in step (1).

[0076] The mass of the dialdehyde starch in step (2) accounts for 0.75% of the mass of the starch in step (1).

[0077] The mass of furfural in step (3) accounts for 0.4% of the mass of starch in step (1), and the mass of m-cresol accounts for 0.3% of the mass of starch in step (1).

[0078] The mass of salicylic acid in step (3) accounts for 1.2% of the mass of starch in step (1).

[0079] In step (3), the copolymerization reaction temperature is 67° C. and the copolymerization reaction time is 2 h.

[0080] The mass of polyhydroxyethyl methacrylate in step (3) accounts for 1.2% of the mass of starch in step (1), and the mass of vinyl acetate acrylate copolymer accounts for 0.4% of the mass of starch in step (1).

[0081] Comparative Example 1

[0082] The preparation method of the starch adhesive for corrugated paper described in this comparative example 1 is the same as that of Example 1, the only difference being that only phosphorus oxychloride is added in step (2).

[0083] Comparative Example 2

[0084] The preparation method of the starch adhesive for corrugated paper described in Comparative Example 2 is the same as that in Example 1, with the only difference being that only dialdehyde starch is added in step (2).

[0085] Comparative Example 3

[0086] The preparation method of the starch adhesive for corrugated paper described in this comparative example 3 is the same as that in Example 1, the only difference being that polyhydroxyethyl methacrylate and vinyl acetate acrylate copolymer are no longer added in step (3).

[0087] The starch adhesives prepared in Examples 1-3 and Comparative Examples 1-3 were tested for performance, and the results are shown in Table 1 below:

[0088] Table 1 Test results of starch adhesive properties for corrugated paper

[0089]

[0090] The starch adhesives prepared in Examples 1-3 and Comparative Examples 1-3 were used in the production of corrugated paper, and the performance of the produced corrugated paper was tested. The results are shown in Table 2 below:

[0091] Table 2 Corrugated paper test results

[0092]

Claims

1. A method for preparing a starch adhesive for corrugated paper, characterized in that: It consists of the following steps: (1) adding water to starch and stirring to form a paste, then adding sulfuric acid solution and potassium permanganate solution and mixing, oxidizing at 45-48° C. for 2.8-3 hours, and cooling to room temperature to prepare a first reactant; (2) adding water to the first reactant under stirring and mixing, then adding sodium hydroxide solution and continuing the reaction for 50-55 minutes, and finally adding phosphorus oxychloride and dialdehyde starch and reacting at 38-40° C. for 2.3-2.5 hours to prepare a second reactant; (3) adding furfural, m-cresol and salicylic acid to the second reactant prepared in step (2) for copolymerization, and finally adding polyhydroxyethyl methacrylate and vinyl acetate acrylate copolymer and stirring evenly to prepare a starch adhesive for corrugated paper; in: The mass of phosphorus oxychloride in step (2) accounts for 0.003-0.005% of the mass of starch in step (1); The mass of the dialdehyde starch in step (2) accounts for 0.55-0.75% of the mass of the starch in step (1); The mass of furfural in step (3) accounts for 0.4-0.5% of the mass of starch in step (1), and the mass of m-cresol accounts for 0.2-0.3% of the mass of starch in step (1).

2. The method for preparing the starch adhesive for corrugated paper according to claim 1, characterized in that: The starch described in step (1) is corn starch; The mass ratio of starch to water in step (1) is 1:1.5-1.

7.

3. The method for preparing the starch adhesive for corrugated paper according to claim 1, characterized in that: The concentration of the sulfuric acid solution in step (1) is 2.5 mol / L, and the mass ratio of the volume of the sulfuric acid solution to the starch is 1:9.6, in units of mL / g; The mass concentration of the potassium permanganate solution in step (1) is 3.3%, and the mass ratio of the volume of the potassium permanganate solution to the starch is 1:2, in units of mL / g.

4. The method for preparing the starch adhesive for corrugated paper according to claim 1, characterized in that: The mass ratio of the water in step (1) to the water in step (2) is 1:1.4-1.

6.

5. The method for preparing the starch adhesive for corrugated paper according to claim 1, characterized in that: The mass concentration of the sodium hydroxide solution in step (2) is 25%, and the volume ratio of the sodium hydroxide solution to the starch is 11:25, in units of mL / g.

6. The method for preparing the starch adhesive for corrugated paper according to claim 1, characterized in that: The mass of salicylic acid in step (3) accounts for 1.2% of the mass of starch in step (1).

7. The method for preparing the starch adhesive for corrugated paper according to claim 1, characterized in that: In step (3), the copolymerization reaction temperature is 65-67° C., and the copolymerization reaction time is 2 h.

8. The method for preparing the starch adhesive for corrugated paper according to claim 1, characterized in that: The mass of the polyhydroxyethyl methacrylate in step (3) accounts for 1.0-1.2% of the mass of the starch in step (1), and the mass of the vinyl acetate acrylate copolymer accounts for 0.4-0.6% of the mass of the starch in step (1).

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