Preparation method of an oxidized starch / polyaspartic acid composite adhesive

Abstract

The invention discloses a preparation method of an oxidized starch / polyaspartic acid composite adhesive. By stepwise oxidation of starch and addition of polyaspartic acid, the bonding strength, water resistance and stability of the oxidized starch-based adhesive are improved.

Description

Technical Field

[0001] The invention relates to a preparation method of an oxidized starch / polyaspartic acid composite adhesive, and belongs to the technical field of starch-based adhesives. Background Art

[0002] With the depletion of non-renewable resources and the environmental pollution caused by synthetic polymers, people have begun to focus on the development and utilization of renewable polymer resources such as starch, cellulose, and lignin. Compared to traditional non-renewable resources, these renewable polymer resources are widely available, inexpensive, and biodegradable upon disposal, making them environmentally friendly. Adhesives, as one of the five major synthetic materials in industry (the other four being plastics, synthetic rubber, coatings, and synthetic fibers), play a vital role in industrial production and improving people's living standards. In recent years, with the increasing national attention paid to environmental protection, and the widespread industrial use of "trialdehyde" adhesives that produce harmful formaldehyde gas and pose a threat to public health, the use of renewable resources to prepare green and environmentally friendly adhesives has attracted increasing research attention. Starch, as a renewable polymer material, has the advantages of being widely available, inexpensive, pollution-free, and easy to use. It is widely used in the synthesis of environmentally friendly adhesives, becoming an ideal alternative to traditional synthetic resin adhesives and is commonly used in bonding paper, cardboard, and wood. However, the current starch adhesives have low bonding strength and poor stability, and there is still a certain gap compared with conventional organic solvent adhesives.

[0003] The oxidized starch-based composite polyaspartic acid adhesive of the present invention is mainly used in the fields of paper products, wood products and packaging.

[0004] Polyaspartic acid, as an amino acid polymer, has good biodegradability and is a green, pollution-free, environmentally friendly chemical. It also has good dispersing properties and can be used as a dispersant.

[0005] Polyaspartic acid contains a large amount of imino groups, which can combine with the carboxyl groups derived from the oxidation of hydroxyl groups in oxidized starch, thereby improving the bonding strength and stability of the adhesive. Summary of the Invention

[0006] The purpose of the present invention is to significantly improve the bonding strength, water resistance and stability of an oxidized starch adhesive by adding a modifier, thereby obtaining a high-strength, low-cost, and highly practical starch-based adhesive.

[0007] To achieve the above objectives, the present invention adopts the following technical solutions:

[0008] A method for preparing an oxidized starch / polyaspartic acid composite adhesive, the raw material components of which include: 100 parts of starch, 400-600 parts of water, 8-15 parts of sodium hydroxide, 1-3 parts of a catalyst, 3-7 parts of an oxidizing agent, 1-4 parts of a reducing agent, 0.5-3 parts of sodium lauryl sulfate, 0.5-3 parts of a sucrose fatty acid ester, 8-20 parts of urea, 0.5-4.5 parts of borax, 0.5-4 parts of sodium tripolyphosphate, 10-60 parts of polyaspartic acid, 0.2-1 part of tributyl phosphate, and 10-30 parts of a drier; the parts mentioned above are all by mass.

[0009] The catalyst is selected from at least one of nickel sulfate and ferrous sulfate, the oxidant is hydrogen peroxide, and the reducing agent is sodium thiosulfate;

[0010] The preparation method comprises:

[0011] (1) using the above raw material components to prepare the following four aqueous solutions: a sodium hydroxide aqueous solution, a mixed aqueous solution of sodium lauryl sulfate, sucrose fatty acid ester and urea, a polyaspartic acid aqueous solution, and a mixed aqueous solution of sodium tripolyphosphate and borax;

[0012] (2) taking a portion of the starch, the catalyst, and the remaining water, mixing them, adjusting the pH to 9-10 with a sodium hydroxide aqueous solution while stirring, then adding an oxidant to oxidize for 30-60 minutes, then adding the remaining starch and continuing to oxidize for 30-60 minutes, and then adding a reducing agent to stop the oxidation, thereby obtaining a mixture containing oxidized starch;

[0013] (3) adding the polyaspartic acid aqueous solution and the remaining sodium hydroxide aqueous solution to the mixture containing oxidized starch obtained in step (2) for gelatinization, wherein the gelatinization time is 20-50 minutes;

[0014] (4) adding a mixed aqueous solution of sodium lauryl sulfate, sucrose fatty acid ester and urea to the mixture obtained in step (3), adding a defoaming agent, and stirring for 4-12 minutes;

[0015] (5) adding a mixed aqueous solution of sodium tripolyphosphate and borax to the mixture obtained in step (4) and subjecting the mixture to a cross-linking reaction for 20-50 minutes;

[0016] (6) adding a drying agent to the mixture obtained in step (5) and stirring and dispersing the mixture thoroughly;

[0017] (7) Collecting the sample to obtain the oxidized starch / polyaspartic acid composite adhesive.

[0018] Preferably, the starch is any one of corn starch and tapioca starch.

[0019] Preferably, the water is tap water or deionized water.

[0020] Preferably, the ratio of the total number of parts of the sodium lauryl sulfate and the sucrose fatty acid ester to the number of parts of the starch is 1-4:100.

[0021] Preferably, the ratio of the total number of borax and sodium tripolyphosphate to the number of starch is 2-5:100.

[0022] More preferably, the raw material components include: 100 parts of starch, 450-600 parts of water, 10-12 parts of sodium hydroxide, 1.5-2 parts of catalyst, 4-6 parts of oxidant, 2-3 parts of reducing agent, 1-1.5 parts of sodium lauryl sulfate, 1.5-2 parts of sucrose fatty acid ester, 10-15 parts of urea, 1.5-2 parts of borax, 0.5-1 part of sodium tripolyphosphate, 15-40 parts of polyaspartic acid, 0.2-1.5 parts of tributyl phosphate, and 15-20 parts of drying agent.

[0023] Preferably, the drying agent comprises kaolin, montmorillonite, titanium dioxide, ammonium chloride, and potassium aluminum sulfate. Further preferably, the particle sizes of the kaolin and montmorillonite are below the micron level. Further preferably, the ratio of the total mass of titanium dioxide, ammonium chloride, and potassium aluminum sulfate in the drying agent to the total mass of kaolin and montmorillonite is 1:2-10, and more preferably 1:3-7; the mass ratio of montmorillonite to kaolin is 5-8:8-12, and the mass ratio of titanium dioxide, ammonium chloride, and potassium aluminum sulfate is 6-10:1-2:1-2.

[0024] Preferably, the concentration of the sodium hydroxide aqueous solution is 10-20 wt%.

[0025] Preferably, the concentration of borax in the mixed aqueous solution of sodium tripolyphosphate and borax is 1.0-2.5 wt%.

[0026] Preferably, the concentration of the polyaspartic acid aqueous solution is 10-30 wt%.

[0027] Preferably, the total concentration of the mixed aqueous solution of sodium lauryl sulfate, sucrose fatty acid ester and urea is 10-40 wt%.

[0028] Preferably, in step (2), only half of the total amount of starch is added at the beginning, and the remaining starch is added when the oxidation time reaches half of the total oxidation time.

[0029] Preferably, the entire preparation process of the oxidized starch / polyaspartic acid composite adhesive is carried out at room temperature and stirred throughout the process. Before adding the drying agent, the stirring speed should be 250-450 r / min, and after adding the drying agent, the stirring speed should be 500-700 r / min, and the stirring and dispersion time is 60-120 min, more preferably 60-90 min.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) The present invention greatly improves the bonding strength, water resistance and stability of the adhesive by adding polyaspartic acid to the starch-based adhesive.

[0032] (2) The present invention uses a step-by-step oxidation modification of starch, where one portion of the starch is oxidized for a long time and another portion for a short time, resulting in a uniform distribution of long-chain and short-chain starch molecules throughout the adhesive, significantly increasing the fluidity and bonding strength of the starch glue. Furthermore, the oxidized starch has a certain amount of carboxyl groups that can better bind to polyaspartic acid, significantly improving not only the dispersibility and stability of the glue but also the bonding strength of the starch glue.

[0033] (3) The adhesive obtained by using the drying agent used in the present invention has a faster drying speed than the adhesive obtained by using conventional drying agents.

[0034] (4) Due to the material properties of the adhesive of the present invention, no environmental pollutants will be generated during the experiment. The adhesive itself is biodegradable and harmless to the environment.

[0035] (5) In summary, the oxidized starch / polyaspartic acid composite adhesive prepared by the method of the present invention has high bonding strength, dispersibility and stability, and has certain water resistance and good fluidity, and can be applied to paper products, wood products and packaging industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 30 min water loss rate comparison chart of the adhesives prepared in Example 2 and Comparative Examples 1-3.

[0037] Figure 2 3 is a comparison chart of the bonding strength and viscosity of the adhesives prepared in Example 3 and Comparative Examples 4-6.

[0038] Figure 3 3 is a comparison chart of the water resistance of the adhesives prepared in Example 3 and Comparative Examples 4-6.

[0039] Figure 4 5 is a comparison chart of the bonding strength and viscosity of the adhesives prepared in Example 5, Comparative Example 7, and Comparative Example 8.

[0040] Figure 5 3 is a comparison chart of the water resistance of the adhesives prepared in Example 5, Comparative Example 7, and Comparative Example 8. DETAILED DESCRIPTION

[0041] To make the objects, technical solutions, and advantages of the present invention more apparent, the technical solutions will be further described clearly and completely below through the examples. Where specific conditions are not specified in the examples, conventional conditions or conditions recommended by the manufacturer were followed. Reagents or instruments used, where the manufacturer is not specified, are all commercially available conventional products.

[0042] The sources of the reagents used in the examples are as follows: corn starch was provided by Hefei Xuegong Packaging Machinery Co., Ltd.; sodium hydroxide was purchased from Xilong Science Co., Ltd.; nickel sulfate, hydrogen peroxide, sodium thiosulfate, urea, ammonium chloride, and potassium aluminum sulfate were purchased from Sinopharm Chemical Reagent Co., Ltd.; sodium lauryl sulfate, sodium tripolyphosphate, and tributyl phosphate were purchased from Aladdin Reagent Co., Ltd.; borax was purchased from Roan Reagent; polyaspartic acid was purchased from Yuanye Biotechnology Co., Ltd.; and sucrose fatty acid esters were purchased from Zhejiang Hetang Technology Co., Ltd.

[0043] Example 1:

[0044] Accurately weigh, according to mass fraction, 100 parts of corn starch, 450 parts of tap water, 10 parts of sodium hydroxide, 2 parts of nickel sulfate, 4 parts of hydrogen peroxide, 2 parts of sodium thiosulfate, 1 part of sodium lauryl sulfate (SDS), 2 parts of sucrose fatty acid ester (SE), 15 parts of urea, 1.5 parts of borax, 0.5 part of sodium tripolyphosphate, 15 parts of polyaspartic acid, 0.2 part of tributyl phosphate, and 15 parts of a drying agent (5 parts of montmorillonite (micron grade, same as other embodiments), 8 parts of kaolin (micron grade, same as other embodiments), 1.6 parts of titanium dioxide, 0.2 part of ammonium chloride, and 0.2 part of potassium aluminum sulfate).

[0045] Accurately weigh 10 parts of sodium hydroxide in a beaker, add 50 parts of tap water, and stir with a glass rod to dissolve, to obtain a sodium hydroxide aqueous solution and store for later use; accurately weigh 1.5 parts of borax and 0.5 parts of sodium tripolyphosphate in a beaker, add 100 parts of tap water, and stir magnetically to dissolve, to obtain a mixed aqueous solution of sodium tripolyphosphate and borax and store for later use; accurately weigh 15 parts of polyaspartic acid in a beaker, add 50 parts of tap water, and stir magnetically to dissolve, to obtain a polyaspartic acid aqueous solution and store for later use; accurately weigh 1 part of SDS, 2 parts of SE, and 15 parts of urea in a beaker, add 50 parts of tap water, and stir magnetically to dissolve, to obtain a mixed aqueous solution of sodium lauryl sulfate, sucrose fatty acid ester, and urea and store for later use.

[0046] 50 parts of starch are dissolved in 200 parts of water, nickel sulfate is added and placed under mechanical stirring and stirred at 300r / min speed, pH is adjusted to 10 with the sodium hydroxide solution of configuration, and after adding hydrogen peroxide oxidation for 45 minutes, the remaining 50 parts of starch are added, sodium thiosulfate is added after continuing oxidation for 45min, and it is treated that it reacts for 5min. Then polyaspartic acid solution is added, and the remaining sodium hydroxide solution is added dropwise, and reacts for 30min. After the reaction is completed, SDS, SE and urea mixed solution are added, and tributyl phosphate is added dropwise, stirred for 10min, and then borax, sodium tripolyphosphate mixed solution are added dropwise, and it is reacted for 30min. Finally, siccative (5 parts of montmorillonite, 8 parts of kaolin, 1.6 parts of titanium dioxide, 0.2 part of ammonium chloride, 0.2 part of potassium aluminum sulfate) is added, and the speed is adjusted to 550r / min, and the sample is collected after dispersion for 60min.

[0047] Example 2:

[0048] Accurately weigh 100 parts of corn starch, 500 parts of tap water, 12 parts of sodium hydroxide, 3 parts of nickel sulfate, 6 parts of hydrogen peroxide, 3 parts of sodium thiosulfate, 1.5 parts of sodium dodecyl sulfate (SDS), 1.5 parts of sucrose fatty acid ester (SE), 15 parts of urea, 2 parts of borax, 1 part of sodium tripolyphosphate, 20 parts of polyaspartic acid, 0.2 part of tributyl phosphate, and 15 parts of a drying agent (5 parts of montmorillonite, 8 parts of kaolin, 1.6 parts of titanium dioxide, 0.2 part of ammonium chloride, and 0.2 part of potassium aluminum sulfate) according to the mass fraction.

[0049] Accurately weigh 12 parts of sodium hydroxide in a beaker, add 50 parts of tap water, and stir with a glass rod to dissolve, to obtain a sodium hydroxide aqueous solution and store for later use; accurately weigh 2 parts of borax and 1 part of sodium tripolyphosphate in a beaker, add 120 parts of tap water, and dissolve with magnetic stirring to obtain a mixed aqueous solution of sodium tripolyphosphate and borax and store for later use; accurately weigh 20 parts of polyaspartic acid in a beaker, add 70 parts of tap water, and dissolve with magnetic stirring to obtain a polyaspartic acid aqueous solution and store for later use; accurately weigh 1.5 parts of SDS, 1.5 parts of SE, and 15 parts of urea in a beaker, add 60 parts of tap water, and dissolve with magnetic stirring to obtain a mixed aqueous solution of sodium lauryl sulfate, sucrose fatty acid ester, and urea and store for later use.

[0050] 50 parts of starch are dissolved in 200 parts of water, nickel sulfate is added and placed under mechanical stirring and stirred at 300r / min speed, pH is adjusted to 10 with the sodium hydroxide solution of configuration, and after adding hydrogen peroxide oxidation for 30 minutes, the remaining 50 parts of starch are added, sodium thiosulfate is added after continuing oxidation for 30min, and it is treated that it reacts for 5min. Then polyaspartic acid solution is added, and remaining sodium hydroxide solution is added dropwise, and reacts for 30min. After the reaction is completed, SDS, SE and urea mixed solution are added, and tributyl phosphate is added dropwise, stirred for 10min, and then borax, sodium tripolyphosphate mixed solution are added dropwise, and it is reacted for 30min. Finally, siccative (5 parts of montmorillonite, 8 parts of kaolin, 1.6 parts of titanium dioxide, 0.2 part of ammonium chloride, 0.2 part of potassium aluminum sulfate) is added, and the speed is adjusted to 550r / min, and sample is collected after dispersion for 60min.

[0051] Comparative Example 1

[0052] Accurately weigh 100 parts of corn starch, 500 parts of tap water, 12 parts of sodium hydroxide, 3 parts of nickel sulfate, 6 parts of hydrogen peroxide, 3 parts of sodium thiosulfate, 1.5 parts of sodium lauryl sulfate (SDS), 1.5 parts of sucrose fatty acid ester (SE), 15 parts of urea, 2 parts of borax, 1 part of sodium tripolyphosphate, 20 parts of polyaspartic acid, 0.2 parts of tributyl phosphate, and 15 parts of a drying agent (15 parts of montmorillonite) according to the mass fraction.

[0053] Accurately weigh 12 parts of sodium hydroxide in a beaker, add 50 parts of tap water, and stir with a glass rod to dissolve, to obtain a sodium hydroxide aqueous solution and store for later use; accurately weigh 2 parts of borax and 1 part of sodium tripolyphosphate in a beaker, add 120 parts of tap water, and dissolve with magnetic stirring to obtain a mixed aqueous solution of sodium tripolyphosphate and borax and store for later use; accurately weigh 20 parts of polyaspartic acid in a beaker, add 70 parts of tap water, and dissolve with magnetic stirring to obtain a polyaspartic acid aqueous solution and store for later use; accurately weigh 1.5 parts of SDS, 1.5 parts of SE, and 15 parts of urea in a beaker, add 60 parts of tap water, and dissolve with magnetic stirring to obtain a mixed aqueous solution of sodium lauryl sulfate, sucrose fatty acid ester, and urea and store for later use.

[0054] 50 parts of starch were dissolved in 200 parts of water, nickel sulfate was added and placed under mechanical stirring at a speed of 300 r / min. The pH was adjusted to 10 with a prepared sodium hydroxide solution. After 30 minutes of oxidation with hydrogen peroxide, the remaining 50 parts of starch were added. After continuing oxidation for 30 minutes, sodium thiosulfate was added and the reaction was allowed to proceed for 5 minutes. Polyaspartic acid solution was then added, and the remaining sodium hydroxide solution was added dropwise and reacted for 30 minutes. After the reaction was completed, a mixed solution of SDS, SE and urea was added, and tributyl phosphate was added dropwise, stirred for 10 minutes, and then a mixed solution of borax and sodium tripolyphosphate was added dropwise and allowed to react for 30 minutes. Finally, a drier (15 parts of montmorillonite) was added, and the speed was adjusted to 550 r / min. The sample was collected after 60 minutes of dispersion.

[0055] Comparative Example 2

[0056] Accurately weigh 100 parts of corn starch, 500 parts of tap water, 12 parts of sodium hydroxide, 3 parts of nickel sulfate, 6 parts of hydrogen peroxide, 3 parts of sodium thiosulfate, 1.5 parts of sodium dodecyl sulfate (SDS), 1.5 parts of sucrose fatty acid ester (SE), 15 parts of urea, 2 parts of borax, 1 part of sodium tripolyphosphate, 20 parts of polyaspartic acid, 0.2 parts of tributyl phosphate, and 15 parts of a drying agent (15 parts of kaolin).

[0057] Accurately weigh 12 parts of sodium hydroxide in a beaker, add 50 parts of tap water, and stir with a glass rod to dissolve, to obtain a sodium hydroxide aqueous solution, which is stored for later use; accurately weigh 2 parts of borax and 1 part of sodium tripolyphosphate in a beaker, add 120 parts of tap water, and dissolve with magnetic stirring to obtain a mixed aqueous solution of sodium tripolyphosphate and borax, which is stored for later use; accurately weigh 20 parts of polyaspartic acid in a beaker, add 70 parts of tap water, and dissolve with magnetic stirring to obtain a polyaspartic acid aqueous solution, which is stored for later use; accurately weigh 1.5 parts of SDS, 1.5 parts of SE, and 15 parts of urea in a beaker, add 60 parts of tap water, and dissolve with magnetic stirring to obtain a mixed aqueous solution of sodium lauryl sulfate, sucrose fatty acid ester, and urea, which is stored for later use.

[0058] 50 parts of starch were dissolved in 200 parts of water, nickel sulfate was added and placed under mechanical stirring at a speed of 300r / min, the pH was adjusted to 10 with the configured sodium hydroxide solution, and the remaining 50 parts of starch were added after adding hydrogen peroxide oxidation for 30 minutes. After continuing oxidation for 30min, sodium thiosulfate was added and the reaction was allowed to proceed for 5min. Then polyaspartic acid solution was added, and the remaining sodium hydroxide solution was added dropwise and reacted for 30min. After the reaction was completed, SDS, SE and urea mixed solution were added, and tributyl phosphate was added dropwise, stirred for 10min, and then borax and sodium tripolyphosphate mixed solution were added dropwise and reacted for 30min. Finally, a drier (15 parts of kaolin) was added, and the speed was adjusted to 550r / min. The sample was collected after 60min of dispersion.

[0059] Comparative Example 3

[0060] Accurately weigh 100 parts of corn starch, 500 parts of tap water, 12 parts of sodium hydroxide, 3 parts of nickel sulfate, 6 parts of hydrogen peroxide, 3 parts of sodium thiosulfate, 1.5 parts of sodium lauryl sulfate (SDS), 1.5 parts of sucrose fatty acid ester (SE), 15 parts of urea, 2 parts of borax, 1 part of sodium tripolyphosphate, 20 parts of polyaspartic acid, 0.2 part of tributyl phosphate, and 15 parts of a drying agent (6 parts of montmorillonite and 9 parts of kaolin).

[0061] Accurately weigh 12 parts of sodium hydroxide in a beaker, add 50 parts of tap water, and stir with a glass rod to dissolve, to obtain a sodium hydroxide aqueous solution and store for later use; accurately weigh 2 parts of borax and 1 part of sodium tripolyphosphate in a beaker, add 120 parts of tap water, and dissolve with magnetic stirring to obtain a mixed aqueous solution of sodium tripolyphosphate and borax and store for later use; accurately weigh 20 parts of polyaspartic acid in a beaker, add 70 parts of tap water, and dissolve with magnetic stirring to obtain a polyaspartic acid aqueous solution and store for later use; accurately weigh 1.5 parts of SDS, 1.5 parts of SE, and 15 parts of urea in a beaker, add 60 parts of tap water, and dissolve with magnetic stirring to obtain a mixed aqueous solution of sodium lauryl sulfate, sucrose fatty acid ester, and urea and store for later use.

[0062] 50 parts of starch were dissolved in 200 parts of water, nickel sulfate was added and placed under mechanical stirring at a speed of 300 r / min, the pH was adjusted to 10 with the sodium hydroxide solution of the configuration, and the remaining 50 parts of starch were added after adding hydrogen peroxide oxidation for 30 minutes. After continuing oxidation for 30 minutes, sodium thiosulfate was added and the reaction was allowed to proceed for 5 minutes. Then polyaspartic acid solution was added, and the remaining sodium hydroxide solution was added dropwise and reacted for 30 minutes. After the reaction was completed, SDS, SE and urea mixed solution were added, and tributyl phosphate was added dropwise, stirred for 10 minutes, and then borax and sodium tripolyphosphate mixed solution were added dropwise, and the reaction was allowed to proceed for 30 minutes. Finally, a drier (6 parts of montmorillonite and 9 parts of kaolin) was added, and the speed was adjusted to 550 r / min. The sample was collected after 60 minutes of dispersion.

[0063] Example 3:

[0064] Accurately weigh 100 parts of corn starch, 600 parts of tap water, 10 parts of sodium hydroxide, 2 parts of nickel sulfate, 4 parts of hydrogen peroxide, 2 parts of sodium thiosulfate, 1 part of sodium lauryl sulfate (SDS), 2 parts of sucrose fatty acid ester (SE), 20 parts of urea, 2 parts of borax, 1 part of sodium tripolyphosphate, 15 parts of polyaspartic acid, 0.4 part of tributyl phosphate, and 20 parts of a drying agent (5 parts of montmorillonite, 10 parts of kaolin, 4 parts of titanium dioxide, 0.5 part of ammonium chloride, and 0.5 part of potassium aluminum sulfate) according to the mass fraction.

[0065] Accurately weigh 10 parts of sodium hydroxide in a beaker, add 60 parts of tap water, and stir with a glass rod to dissolve, to obtain a sodium hydroxide aqueous solution and store for later use; accurately weigh 2 parts of borax and 1 part of sodium tripolyphosphate in a beaker, add 120 parts of tap water, and dissolve with magnetic stirring to obtain a mixed aqueous solution of sodium tripolyphosphate and borax and store for later use; accurately weigh 15 parts of polyaspartic acid in a beaker, add 70 parts of tap water, and dissolve with magnetic stirring to obtain a polyaspartic acid aqueous solution and store for later use; accurately weigh 1 part of SDS, 2 parts of SE, and 20 parts of urea in a beaker, add 100 parts of tap water, and dissolve with magnetic stirring to obtain a mixed aqueous solution of sodium lauryl sulfate, sucrose fatty acid ester, and urea and store for later use.

[0066] 50 parts of starch are dissolved in 250 parts of water, nickel sulfate is added and placed under mechanical stirring and stirred at 300r / min speed, pH is adjusted to 10 with the sodium hydroxide solution of configuration, and the remaining 50 parts of starch are added after adding hydrogen peroxide oxidation for 45 minutes, sodium thiosulfate is added after continuing oxidation for 45min, and it is treated that it reacts for 5min. Then polyaspartic acid solution is added, and the remaining sodium hydroxide solution is added dropwise and reacted for 30min. After the reaction is completed, SDS, SE and urea mixed solution are added, and tributyl phosphate is added dropwise simultaneously, stirred for 10min, and then borax, sodium tripolyphosphate mixed solution are added dropwise, and it is reacted for 30min. Finally, siccative (5 parts of montmorillonite, 10 parts of kaolin, 4 parts of titanium dioxide, 0.5 part of ammonium chloride, 0.5 part of potassium aluminum sulfate) is added, and the speed is adjusted to 600r / min, and sample is collected after dispersion for 90min.

[0067] Comparative Example 4:

[0068] Accurately weigh 100 parts of corn starch, 600 parts of tap water, 10 parts of sodium hydroxide, 2 parts of nickel sulfate, 4 parts of hydrogen peroxide, 2 parts of sodium thiosulfate, 1 part of sodium lauryl sulfate (SDS), 2 parts of sucrose fatty acid ester (SE), 20 parts of urea, 2 parts of borax, 1 part of sodium tripolyphosphate, 0.4 part of tributyl phosphate, and 20 parts of drier (5 parts of montmorillonite, 10 parts of kaolin, 4 parts of titanium dioxide, 0.5 part of ammonium chloride, and 0.5 part of potassium aluminum sulfate) according to the mass fraction.

[0069] Accurately weigh 10 parts of sodium hydroxide in a beaker, add 60 parts of tap water, and stir with a glass rod to dissolve, to obtain a sodium hydroxide aqueous solution and store for later use; accurately weigh 2 parts of borax and 1 part of sodium tripolyphosphate in a beaker, add 120 parts of tap water, and dissolve with magnetic stirring to obtain a mixed aqueous solution of sodium tripolyphosphate and borax and store for later use; accurately weigh 1 part of SDS, 2 parts of SE, and 20 parts of urea in a beaker, add 70 parts of tap water, and dissolve with magnetic stirring to obtain a mixed aqueous solution of sodium lauryl sulfate, sucrose fatty acid ester, and urea and store for later use.

[0070] 50 parts of starch are dissolved in 350 parts of water, nickel sulfate is added and placed under mechanical stirring and stirred at 300r / min speed, pH is adjusted to 10 with the sodium hydroxide solution of configuration, and the remaining 50 parts of starch are added after adding hydrogen peroxide oxidation for 45 minutes, sodium thiosulfate is added after continuing oxidation for 45min, and wait for its reaction for 5min. Then polyaspartic acid solution is added, and the remaining sodium hydroxide solution is added dropwise and reacted for 30min. After the reaction is completed, SDS, SE and urea mixed solution are added, and tributyl phosphate is added dropwise, stirred for 10min, and then borax, sodium tripolyphosphate mixed solution are added dropwise, and it is reacted for 30min. Finally, siccative (5 parts of montmorillonite, 10 parts of kaolin, 4 parts of titanium dioxide, 0.5 part of ammonium chloride, 0.5 part of potassium aluminum sulfate) is added, and the speed is adjusted to 600r / min, and the sample is collected after dispersion for 90min.

[0071] Comparative Example 5:

[0072] Accurately weigh 100 parts of corn starch, 600 parts of tap water, 10 parts of sodium hydroxide, 2 parts of nickel sulfate, 4 parts of hydrogen peroxide, 2 parts of sodium thiosulfate, 1 part of sodium lauryl sulfate (SDS), 2 parts of sucrose fatty acid ester (SE), 20 parts of urea, 2 parts of borax, 1 part of sodium tripolyphosphate, 5 parts of polyaspartic acid, 0.4 part of tributyl phosphate, and 20 parts of a drying agent (5 parts of montmorillonite, 10 parts of kaolin, 4 parts of titanium dioxide, 0.5 part of ammonium chloride, and 0.5 part of potassium aluminum sulfate) according to the mass fraction.

[0073] Accurately weigh 10 parts of sodium hydroxide in a beaker, add 60 parts of tap water, and stir with a glass rod to dissolve, to obtain a sodium hydroxide aqueous solution and store for later use; accurately weigh 2 parts of borax and 1 part of sodium tripolyphosphate in a beaker, add 120 parts of tap water, and dissolve with magnetic stirring to obtain a mixed aqueous solution of sodium tripolyphosphate and borax and store for later use; accurately weigh 5 parts of polyaspartic acid in a beaker, add 40 parts of tap water, and dissolve with magnetic stirring to obtain a polyaspartic acid aqueous solution and store for later use; accurately weigh 1 part of SDS, 2 parts of SE, and 20 parts of urea in a beaker, add 80 parts of tap water, and dissolve with magnetic stirring to obtain a mixed aqueous solution of sodium lauryl sulfate, sucrose fatty acid ester, and urea and store for later use.

[0074] 50 parts of starch are dissolved in 300 parts of water, nickel sulfate is added and placed under mechanical stirring and stirred at 300r / min speed, pH is adjusted to 10 with the sodium hydroxide solution of configuration, and the remaining 50 parts of starch are added after adding hydrogen peroxide oxidation for 45 minutes, sodium thiosulfate is added after continuing oxidation for 45min, and it is treated that it reacts for 5min. Then polyaspartic acid solution is added, and remaining sodium hydroxide solution is added dropwise, and reacts for 30min. After the reaction is completed, SDS, SE and urea mixed solution are added, and tributyl phosphate is added dropwise, stirred for 10min, and then borax, sodium tripolyphosphate mixed solution are added dropwise, and it is reacted for 30min. Finally, siccative (5 parts of montmorillonite, 10 parts of kaolin, 4 parts of titanium dioxide, 0.5 part of ammonium chloride, 0.5 part of potassium aluminum sulfate) is added, and the speed is adjusted to 600r / min, and sample is collected after dispersion for 90min.

[0075] Comparative Example 6:

[0076] Accurately weigh 100 parts of corn starch, 600 parts of tap water, 10 parts of sodium hydroxide, 2 parts of nickel sulfate, 4 parts of hydrogen peroxide, 2 parts of sodium thiosulfate, 1 part of sodium lauryl sulfate (SDS), 2 parts of sucrose fatty acid ester (SE), 20 parts of urea, 2 parts of borax, 1 part of sodium tripolyphosphate, 40 parts of polyaspartic acid, 0.4 part of tributyl phosphate, and 20 parts of a drying agent (5 parts of montmorillonite, 10 parts of kaolin, 4 parts of titanium dioxide, 0.5 part of ammonium chloride, and 0.5 part of potassium aluminum sulfate) according to the mass fraction.

[0077] Accurately weigh 10 parts of sodium hydroxide in a beaker, add 50 parts of tap water, and stir with a glass rod to dissolve, to obtain a sodium hydroxide aqueous solution and store for later use; accurately weigh 2 parts of borax and 1 part of sodium tripolyphosphate in a beaker, add 100 parts of tap water, and dissolve with magnetic stirring to obtain a mixed aqueous solution of sodium tripolyphosphate and borax and store for later use; accurately weigh 40 parts of polyaspartic acid in a beaker, add 160 parts of tap water, and dissolve with magnetic stirring to obtain a polyaspartic acid aqueous solution and store for later use; accurately weigh 1 part of SDS, 2 parts of SE, and 20 parts of urea in a beaker, add 90 parts of tap water, and dissolve with magnetic stirring to obtain a mixed aqueous solution of sodium lauryl sulfate, sucrose fatty acid ester, and urea and store for later use.

[0078] 50 parts of starch are dissolved in 200 parts of water, nickel sulfate is added and placed under mechanical stirring and stirred at 300r / min speed, pH is adjusted to 10 with the sodium hydroxide solution of configuration, and after adding hydrogen peroxide oxidation for 45 minutes, the remaining 50 parts of starch are added, sodium thiosulfate is added after continuing oxidation for 45min, and it is treated that it reacts for 5min. Then polyaspartic acid solution is added, and the remaining sodium hydroxide solution is added dropwise and reacted for 30min. After the reaction is completed, SDS, SE and urea mixed solution are added, and tributyl phosphate is added dropwise, stirred for 10min, and then borax, sodium tripolyphosphate mixed solution are added dropwise, and it is reacted for 30min. Finally, siccative (5 parts of montmorillonite, 10 parts of kaolin, 4 parts of titanium dioxide, 0.5 part of ammonium chloride, 0.5 part of potassium aluminum sulfate) is added, and the speed is adjusted to 600r / min, and the sample is collected after dispersion for 90min.

[0079] Example 4:

[0080] Accurately weigh 200 parts of corn starch, 1200 parts of tap water, 24 parts of sodium hydroxide, 3 parts of nickel sulfate, 10 parts of hydrogen peroxide, 5 parts of sodium thiosulfate, 2 parts of sodium lauryl sulfate (SDS), 4 parts of sucrose fatty acid ester (SE), 30 parts of urea, 4 parts of borax, 2 parts of sodium tripolyphosphate, 40 parts of polyaspartic acid, 0.6 parts of tributyl phosphate, and 40 parts of a drying agent (12 parts of montmorillonite, 20 parts of kaolin, 6 parts of titanium dioxide, 1 part of ammonium chloride, and 1 part of potassium aluminum sulfate) according to the mass fraction.

[0081] Accurately weigh 24 parts of sodium hydroxide in a beaker, add 150 parts of tap water, stir with a glass rod to dissolve, and store for later use; accurately weigh 4 parts of borax and 2 parts of sodium tripolyphosphate in a beaker, add 250 parts of tap water, stir with a magnetic stirrer to dissolve, and store for later use; accurately weigh 40 parts of polyaspartic acid in a beaker, add 200 parts of tap water, stir with a magnetic stirrer to dissolve, and store for later use; accurately weigh 2 parts of SDS, 4 parts of SE, and 30 parts of urea in a beaker, add 200 parts of tap water, stir with a magnetic stirrer to dissolve, and store for later use.

[0082] 100 parts of starch are dissolved in 400 parts of water, nickel sulfate is added and placed under mechanical stirring and stirred at 350r / min speed, pH is adjusted to 10 with the sodium hydroxide solution of configuration, and the remaining 100 parts of starch are added after adding hydrogen peroxide oxidation for 60 minutes, sodium thiosulfate is added after continuing oxidation for 60min, and it is treated that it reacts for 5min. Then polyaspartic acid solution is added, and the remaining sodium hydroxide solution is added dropwise and reacted for 30min. After the reaction is completed, SDS, SE and urea mixed solution are added, and tributyl phosphate is added dropwise, stirred for 10min, and then borax, sodium tripolyphosphate mixed solution are added dropwise, and it is reacted for 30min. Finally, siccative (12 parts of montmorillonite, 20 parts of kaolin, 6 parts of titanium dioxide, 1 part of ammonium chloride, 1 part of potassium aluminum sulfate) is added, and the speed is adjusted to 650r / min, and the sample is collected after dispersion for 120min.

[0083] Example 5:

[0084] Accurately weigh 200 parts of corn starch, 1000 parts of tap water, 20 parts of sodium hydroxide, 3 parts of nickel sulfate, 12 parts of hydrogen peroxide, 6 parts of sodium thiosulfate, 3 parts of sodium lauryl sulfate (SDS), 3 parts of sucrose fatty acid ester (SE), 30 parts of urea, 3 parts of borax, 2 parts of sodium tripolyphosphate, 40 parts of polyaspartic acid, 0.5 parts of tributyl phosphate, and 40 parts of a drying agent (10 parts of montmorillonite, 20 parts of kaolin, 8 parts of titanium dioxide, 1 part of ammonium chloride, and 1 part of potassium aluminum sulfate) according to the mass fraction.

[0085] Accurately weigh 20 parts of sodium hydroxide in a beaker, add 100 parts of tap water, stir with a glass rod to dissolve, and store for later use; accurately weigh 3 parts of borax and 2 parts of sodium tripolyphosphate in a beaker, add 200 parts of tap water, stir with a magnetic stirrer to dissolve, and store for later use; accurately weigh 40 parts of polyaspartic acid in a beaker, add 200 parts of tap water, stir with a magnetic stirrer to dissolve, and store for later use; accurately weigh 3 parts of SDS, 3 parts of SE, and 30 parts of urea in a beaker, add 200 parts of tap water, stir with a magnetic stirrer to dissolve, and store for later use.

[0086] 100 parts of starch are dissolved in 300 parts of water, nickel sulfate is added and placed under mechanical stirring and stirred at 350r / min speed, the pH is adjusted to 10 with the sodium hydroxide solution of configuration, and the remaining 100 parts of starch are added after adding hydrogen peroxide oxidation for 45 minutes. After continuing oxidation for 45min, sodium thiosulfate is added and treated to react for 5min. Then polyaspartic acid solution is added, and the remaining sodium hydroxide solution is added dropwise and reacted for 30min. After the reaction is completed, SDS, SE and urea mixed solution are added, and tributyl phosphate is added dropwise, stirred for 10min, and then borax and sodium tripolyphosphate mixed solution are added dropwise, and it is reacted for 30min. Finally, siccative (10 parts of montmorillonite, 20 parts of kaolin, 8 parts of titanium dioxide, 1 part of ammonium chloride, 1 part of potassium aluminum sulfate) is added, and the speed is adjusted to 650r / min. Samples are collected after dispersion for 120min.

[0087] Comparative Example 7:

[0088] Accurately weigh 200 parts of corn starch, 1000 parts of tap water, 20 parts of sodium hydroxide, 3 parts of nickel sulfate, 12 parts of hydrogen peroxide, 6 parts of sodium thiosulfate, 3 parts of sodium lauryl sulfate (SDS), 3 parts of sucrose fatty acid ester (SE), 30 parts of urea, 3 parts of borax, 2 parts of sodium tripolyphosphate, 40 parts of polyaspartic acid, 0.5 parts of tributyl phosphate, and 40 parts of a drying agent (10 parts of montmorillonite, 20 parts of kaolin, 8 parts of titanium dioxide, 1 part of ammonium chloride, and 1 part of potassium aluminum sulfate) according to the mass fraction.

[0089] Accurately weigh 20 parts of sodium hydroxide in a beaker, add 100 parts of tap water, stir with a glass rod to dissolve, and store for later use; accurately weigh 3 parts of borax and 2 parts of sodium tripolyphosphate in a beaker, add 200 parts of tap water, stir with a magnetic stirrer to dissolve, and store for later use; accurately weigh 40 parts of polyaspartic acid in a beaker, add 200 parts of tap water, stir with a magnetic stirrer to dissolve, and store for later use; accurately weigh 3 parts of SDS, 3 parts of SE, and 30 parts of urea in a beaker, add 200 parts of tap water, stir with a magnetic stirrer to dissolve, and store for later use.

[0090] 200 parts of starch were dissolved in 300 parts of water, nickel sulfate was added and placed under mechanical stirring at a speed of 350r / min, the pH was adjusted to 10 with the sodium hydroxide solution of configuration, sodium thiosulfate was added after adding hydrogen peroxide oxidation for 90min, and the reaction was continued for 5min. Then polyaspartic acid solution was added, and the remaining sodium hydroxide solution was added dropwise and reacted for 30min. After the reaction was completed, SDS, SE and urea mixed solution were added, and tributyl phosphate was added dropwise, stirred for 10min, and then borax and sodium tripolyphosphate mixed solution were added dropwise, and the reaction was continued for 30min. Finally, a drier (10 parts of montmorillonite, 20 parts of kaolin, 8 parts of titanium dioxide, 1 part of ammonium chloride, and 1 part of potassium aluminum sulfate) was added, and the speed was adjusted to 650r / min. The sample was collected after dispersion for 120min.

[0091] Comparative Example 8:

[0092] Accurately weigh 200 parts of corn starch, 1000 parts of tap water, 20 parts of sodium hydroxide, 3 parts of nickel sulfate, 12 parts of hydrogen peroxide, 6 parts of sodium thiosulfate, 3 parts of sodium lauryl sulfate (SDS), 3 parts of sucrose fatty acid ester (SE), 30 parts of urea, 3 parts of borax, 2 parts of sodium tripolyphosphate, 40 parts of polyaspartic acid, 0.5 parts of tributyl phosphate, and 40 parts of a drying agent (10 parts of montmorillonite, 20 parts of kaolin, 8 parts of titanium dioxide, 1 part of ammonium chloride, and 1 part of potassium aluminum sulfate) according to the mass fraction.

[0093] Accurately weigh 20 parts of sodium hydroxide in a beaker, add 100 parts of tap water, stir with a glass rod to dissolve, and store for later use; accurately weigh 3 parts of borax and 2 parts of sodium tripolyphosphate in a beaker, add 200 parts of tap water, stir with a magnetic stirrer to dissolve, and store for later use; accurately weigh 40 parts of polyaspartic acid in a beaker, add 200 parts of tap water, stir with a magnetic stirrer to dissolve, and store for later use; accurately weigh 3 parts of SDS, 3 parts of SE, and 30 parts of urea in a beaker, add 200 parts of tap water, stir with a magnetic stirrer to dissolve, and store for later use.

[0094] 100 parts of starch are dissolved in 300 parts of water, nickel sulfate is added and placed under mechanical stirring and stirred at 350r / min speed, pH is not adjusted, and after adding hydrogen peroxide oxidation for 45 minutes, the remaining 100 parts of starch are added, and sodium thiosulfate is added after continuing oxidation for 45min, and it is treated that it reacts for 5min. Then polyaspartic acid solution is added, and remaining sodium hydroxide solution is added dropwise, and reacts for 30min. After the reaction is completed, SDS, SE and urea mixed solution are added, and tributyl phosphate is added dropwise, stirred for 10min, and then borax, sodium tripolyphosphate mixed solution are added dropwise, and it is reacted for 30min. Finally, siccative (10 parts of montmorillonite, 20 parts of kaolin, 8 parts of titanium dioxide, 1 part of ammonium chloride, 1 part of potassium aluminum sulfate) is added, and the speed is adjusted to 650r / min, and sample is collected after dispersion for 120min.

[0095] The adhesives prepared in the above examples and comparative examples were tested for performance, and the testing method was as follows:

[0096] 1. Viscosity measurement

[0097] The viscosity of adhesives was measured according to the method specified in the national standard GBT / 2794-2013 “Determination of viscosity of adhesives: Single cylinder rotational viscometer method”.

[0098] 2. Bond strength determination

[0099] The test method is based on the national standard GB / T 17517-1998 “Test method for compression shear strength of adhesives between wood and wood”.

[0100] 3. Water resistance determination

[0101] Take two wooden blocks with a thickness of 1 cm and a length of 2 cm. 2 ) Apply 0.5g of adhesive, then attach another wooden block to it. Apply 3MPa of pressure for 6 hours. Remove the pressure and let it sit at room temperature for 24 hours. Place the sample in a 60°C water bath to observe if the adhesive debonds, and record the debonding time.

[0102] 4. Stability test

[0103] Store the prepared sample in a 500ml covered container at (23±2)°C in a dry, dark environment. Observe it every 24 hours for gelation or delamination (only the occurrence of either indicates the adhesive has lost stability). Record the time it takes for gelation or delamination to occur. Retest the viscosity of samples that have not deteriorated after 7 days of storage using the viscosity test method described above.

[0104] 5. Drying speed test

[0105] Take two 25cm pieces 2 Take two pieces of corrugated paper of the same size and weigh them as W0. Then apply the sample adhesive and immediately overlap and bond them together and weigh them as W1. At the same time, take two pieces of corrugated paper of the same size and weigh them as W2. Place them in the same environment at (23±2)℃, weigh them and record the weights of the two after 30 minutes. 11 、W 12 Then put them in a 60℃ oven and dry them for 24 hours. Weigh and record their weights after drying. 01 、W 02 The calculation formula for water loss rate at 30 minutes is:

[0106]

[0107] The test results are as follows Figure 1-5 As shown in Table 1-2:

[0108] Example 2 and Comparative Examples 1-3 used different driers. Figure 1 The drying speed test results shown show that the adhesive prepared using the drier of the present invention has a faster drying speed than the catalysts prepared using the drier used in Comparative Examples 1-3.

[0109] Example 3 and Comparative Examples 4-6 added different amounts of polyaspartic acid. Figure 2It can be seen that the addition of polyaspartic acid can effectively improve the bonding strength of starch adhesives, and as the amount added increases, the bonding strength will also be greater, but at the same time, the addition of polyaspartic acid will also affect the viscosity of starch adhesives, and the amount added is proportional to the viscosity. Figure 3 Water resistance test results show that polyaspartic acid can improve the water resistance of starch adhesives to a certain extent, and the water resistance is positively correlated with the amount of polyaspartic acid added. Table 1 also shows that the stability of starch adhesives is significantly improved after the addition of polyaspartic acid. However, excessive amounts of polyaspartic acid can actually reduce the viscosity stability of the adhesive. In summary, the optimal amount of polyaspartic acid added should be within the range specified in this invention.

[0110] Table 1 Stability test

[0111]

[0112] Example 5 is compared with Comparative Example 7 (starch is not hydrolyzed) and Comparative Example 8 (starch is hydrolyzed once). Figure 4 It can be seen that the adhesive made by oxidizing starch in two steps and adjusting the pH to 9-10 has a stronger bonding strength than the adhesive made by oxidizing starch once and adjusting the pH and oxidizing starch twice without adjusting the pH. The adhesive made by oxidizing starch twice without adjusting the pH has the lowest bonding strength. However, in terms of viscosity, the starch adhesive made by oxidizing starch once and adjusting the pH has the lowest viscosity, while the starch adhesive made by oxidizing starch twice without adjusting the pH has the highest viscosity. Figure 5 Water resistance tests show that the oxidation method has little effect on the water resistance of starch adhesives. The data in Table 2 show that after adjusting the pH, both single-stage and double-stage oxidations exhibited relatively good stability, with similar viscosity stability. However, the stability of starch adhesives produced without pH adjustment was significantly worse. In summary, the optimal oxidation process is to adjust the pH to 9-10 and perform two-stage oxidations, as this produces the best performance for starch adhesives.

[0113] Table 2 Stability test

[0114]

[0115] The above description is merely an embodiment of the present application and is not intended to limit the scope of protection of the present application. For those skilled in the art, various modifications and variations of the present application are possible. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A method for preparing an oxidized starch / polyaspartic acid composite adhesive, characterized in that: The raw material components of the preparation method include: 100 parts of starch, 400-600 parts of water, 8-15 parts of sodium hydroxide, 1-3 parts of a catalyst, 3-7 parts of an oxidizing agent, 1-4 parts of a reducing agent, 0.5-3 parts of sodium lauryl sulfate, 0.5-3 parts of a sucrose fatty acid ester, 8-20 parts of urea, 0.5-4.5 parts of borax, 0.5-4 parts of sodium tripolyphosphate, 10-60 parts of polyaspartic acid, 0.2-1 parts of tributyl phosphate, and 10-30 parts of a drying agent; the parts mentioned above are all by mass. The catalyst is selected from at least one of nickel sulfate and ferrous sulfate, the oxidant is hydrogen peroxide, and the reducing agent is sodium thiosulfate; The preparation method comprises: (1) using the above raw material components to prepare the following four aqueous solutions: a sodium hydroxide aqueous solution, a mixed aqueous solution of sodium lauryl sulfate, sucrose fatty acid ester and urea, a polyaspartic acid aqueous solution, and a mixed aqueous solution of sodium tripolyphosphate and borax; (2) taking a portion of the starch, the catalyst, and the remaining water, mixing them, adjusting the pH to 9-10 with a sodium hydroxide aqueous solution while stirring, then adding an oxidant to oxidize for 30-60 minutes, then adding the remaining starch and continuing to oxidize for 30-60 minutes, and then adding a reducing agent to stop the oxidation, thereby obtaining a mixture containing oxidized starch; (3) adding the polyaspartic acid aqueous solution and the remaining sodium hydroxide aqueous solution to the mixture containing oxidized starch obtained in step (2) for gelatinization, wherein the gelatinization time is 20-50 minutes; (4) adding a mixed aqueous solution of sodium lauryl sulfate, sucrose fatty acid ester and urea to the mixture obtained in step (3), adding a defoaming agent, and stirring for 4-12 minutes; (5) adding a mixed aqueous solution of sodium tripolyphosphate and borax to the mixture obtained in step (4) and subjecting the mixture to a cross-linking reaction for 20-50 minutes; (6) adding a drying agent to the mixture obtained in step (5) and stirring and dispersing the mixture thoroughly; the drying agent is composed of kaolin, montmorillonite, titanium dioxide, ammonium chloride and potassium aluminum sulfate, the ratio of the total mass of titanium dioxide, ammonium chloride and potassium aluminum sulfate in the drying agent to the total mass of kaolin and montmorillonite is 1:2-10, the mass ratio of montmorillonite to kaolin is 5-8:8-12, and the mass ratio of titanium dioxide, ammonium chloride and potassium aluminum sulfate is 6-10:1-2:1-2; (7) Collecting the sample to obtain the oxidized starch / polyaspartic acid composite adhesive.

2. The preparation method according to claim 1, wherein: The ratio of the total number of the sodium lauryl sulfate and the sucrose fatty acid ester to the number of the starch is 1-4:

100.

3. The preparation method according to claim 1, wherein: The ratio of the total number of borax and sodium tripolyphosphate to the number of starch is 2-5:

100.

4. The preparation method according to claim 1, wherein: The raw material components include: 100 parts of starch, 450-600 parts of water, 10-12 parts of sodium hydroxide, 1.5-2 parts of a catalyst, 4-6 parts of an oxidizing agent, 2-3 parts of a reducing agent, 1-1.5 parts of sodium lauryl sulfate, 1.5-2 parts of sucrose fatty acid ester, 10-15 parts of urea, 1.5-2 parts of borax, 0.5-1 part of sodium tripolyphosphate, 15-40 parts of polyaspartic acid, 0.2-1.5 parts of tributyl phosphate, and 15-20 parts of a drying agent.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The ratio of the total mass of titanium dioxide, ammonium chloride and potassium aluminum sulfate in the drying agent to the total mass of kaolin and montmorillonite is 1:3-7.

6. The preparation method according to claim 5, wherein: The particle sizes of the kaolin and montmorillonite are below micron level.

7. The preparation method according to any one of claims 1 to 4, characterized in that: In step (2), only half of the total amount of starch is added at the beginning, and the remaining starch is added when the oxidation time reaches half of the total oxidation time.

8. The preparation method according to any one of claims 1 to 4, characterized in that: The concentration of the sodium hydroxide aqueous solution is 10-20 wt %, the concentration of borax in the mixed aqueous solution of sodium tripolyphosphate and borax is 1.0-2.5 wt %, the concentration of the polyaspartic acid aqueous solution is 10-30 wt %, and the total concentration of the mixed aqueous solution of sodium lauryl sulfate, sucrose fatty acid ester and urea is 10-40 wt %.

9. The preparation method according to any one of claims 1 to 4, characterized in that: The entire preparation process of the oxidized starch / polyaspartic acid composite adhesive is carried out at room temperature and is stirred throughout the process. Before adding the drying agent, the stirring speed is 250-450 r / min, and after adding the drying agent, the stirring speed is 500-700 r / min, and the stirring and dispersion time is 60-120 min.

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