Anti-aging and high-temperature-resistant starch adhesive and preparation method thereof

Abstract

The invention relates to an anti-aging and high-temperature-resistant starch adhesive and a preparation method thereof, and the anti-aging and high-temperature-resistant starch adhesive comprises the following components in percentage by weight: 20-25% of starch, 3-5% of carboxymethyl cellulose, 1-2% of sodium hydroxide, 1-2% of sodium polyacrylate, 0.1-0.2% of nano montmorillonite, 0.3-0.8% of calcium lignosulfonate, 0.1-0.3% of a composite antioxidant, 0.5-1% of polyethylene glycol-600 and the balance of water. According to the adhesive disclosed by the invention, multi-path oxidation is blocked through a multi-component antioxidant compound system, the high-temperature dimensional stability is improved through a nano reinforced network, the toughness and heat resistance are balanced through polyethylene glycol, mould breeding is inhibited through the mildew preventive, adhesive layer failure caused by biodegradation is avoided, and long-acting stability of the starch adhesive in high-temperature and humid and hot environments is realized; meanwhile, environmental protection and economical efficiency are considered. The adhesive prepared by the invention is free from bubbling, glue failure and fiber damage in a high-temperature and low-temperature environment, and has good bonding performance and high-temperature and low-temperature resistance; the glass strength reduction rate before and after aging in a damp and hot ozone environment is 15% or below, and the glass has good oxidation and aging resistance.

Description

Technical Field

[0001] The invention relates to an anti-aging and high-temperature resistant starch adhesive and a preparation method thereof, and belongs to the field of adhesives. Background Art

[0002] Natural starch adhesives are widely used in the fields of wood, packaging, textiles, etc. due to their advantages such as low price, renewable nature, and non-toxicity. However, starch is prone to free radical chain oxidation reactions in hot and humid environments, resulting in molecular chain breakage, which manifests as yellowing and brittleness of the adhesive layer. Although traditional modification methods (such as hydrogen peroxide oxidation) can improve initial bonding strength, the oxidation process produces a large number of active free radicals, which accelerate the aging process. Single antioxidants (such as BHT) have high mobility and insufficient thermal stability, making it difficult to inhibit oxidation in the long term. In recent years, some natural antioxidants (such as tannic acid) have been tried to improve starch adhesives, but the following limitations still exist: Single protection system: Antioxidants have isolated mechanisms of action (e.g., only scavenging free radicals or only shielding against UV rays), making them incapable of coping with complex aging environments. Inadequate utilization of bio-based components: Industrial byproducts such as lignin sulfonates are not effectively integrated into the cross-linking network, leaving their functional potential unrealized. Therefore, there is an urgent need to develop an anti-aging starch adhesive based on a multi-stage synergistic protection mechanism. This approach, through the combination of natural antioxidants, nano-reinforcement, and molecular design of bio-based cross-linkers, could achieve both long-term stability and environmental protection. Summary of the Invention

[0003] The present invention provides an anti-aging and high-temperature resistant starch adhesive and a preparation method thereof, which solves the problems of poor anti-aging ability of existing natural starch adhesives and easy yellowing and brittleness of the adhesive layer.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: An anti-aging and high-temperature resistant starch adhesive comprises, by weight percentage, 20-25% starch, 3-5% carboxymethyl cellulose, 1-2% sodium hydroxide, 1-2% sodium polyacrylate, 0.1-0.2% nano-montmorillonite, 0.3-0.8% calcium lignin sulfonate, 0.1-0.3% composite antioxidant, 0.5-1% polyethylene glycol-6000, and the balance is water.

[0005] Furthermore, preferably, the composite antioxidant is composed of 3-5 parts of gallnut extract, 6-10 parts of antioxidant 168, 20-30 parts of chitosan and 6-8 parts of preservative, based on weight.

[0006] Furthermore, preferably: the preservative is benzoate or sorbate.

[0007] Furthermore, preferably: the starch is one or a combination of more than one of corn starch, tapioca starch, wheat starch and sweet potato starch.

[0008] Furthermore, preferably: the molecular weight of the sodium polyacrylate is 4-6 million, and the particle size is 60-100 mesh.

[0009] The preparation method of the anti-aging starch adhesive of the present invention comprises the following steps: (1) Starch gelatinization: Mix starch with 3 / 4 formula water, heat to 70-85℃, rotate at 600-800 rpm, stir for 20-30 minutes to obtain a uniform gelatinized liquid, and cool to 60℃ for use; (2) Mix polyethylene glycol-600 and the remaining water evenly, then add the composite oxidant, rotate at 600-800 rpm, and stir for 20-30 minutes to form an oxidant solution; (3) Place the gelatinized liquid in a constant temperature water bath at 60°C, add sodium hydroxide, and stir at a speed of 600-800 rpm for 10-20 minutes; (4) Add sodium polyacrylate, react at 65-70°C, speed 600-800 rpm, and stir for 10-20 minutes; (5) Add carboxymethyl cellulose, nano-montmorillonite and calcium lignin sulfonate in sequence, and continue stirring at a speed of 1500-2000 rpm for 8-10 minutes; (6) Slowly add the oxidant solution using a peristaltic pump for 15 min while maintaining the temperature at 60 °C. (7) After the addition is complete, stir at a speed of 1500-2000 rpm for 5-10 minutes and then vacuum degas; (8) Filter and fill.

[0010] Furthermore, preferably: the vacuum degassing is specifically -0.09MPa, 10-20min.

[0011] Beneficial effects of the present invention: The adhesive of this invention utilizes a multi-component antioxidant system to block multipath oxidation. A nano-reinforced network (nano-montmorillonite / calcium ligninsulfonate) enhances high-temperature dimensional stability. Polyethylene glycol balances toughness and heat resistance. A mildewcide inhibits mold growth, preventing adhesive failure due to biodegradation. This ensures the long-term stability of starch adhesives in high-temperature and humid environments, while also balancing environmental and economic considerations. The adhesive prepared in this invention exhibits excellent bonding performance and high- and low-temperature resistance, with no bubbling, debonding, or fiber damage, even in high- and low-temperature environments. The glass strength reduction rate before and after aging in a humid, ozone-containing environment is less than 15%, demonstrating excellent resistance to oxidative aging. DETAILED DESCRIPTION

[0012] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work are not included.

[0013] The raw materials used in this embodiment are as follows: The starch is corn starch; the molecular weight of sodium polyacrylate is 4-5 million, and the particle size is 80 mesh; the tannic acid content of the gallnut extract is ≥95%. There are no special requirements for other raw materials, as long as they meet the relevant standards.

[0014] Examples 1-5 investigate the effects of different antioxidant raw material compositions on the product An anti-aging and high-temperature resistant starch adhesive comprises, by weight, 20% corn starch, 5% carboxymethyl cellulose, 1% sodium hydroxide, 0.2% composite antioxidant, and the balance water. The specific composition of the composite antioxidant is shown in Table 1. The preservative is sodium benzoate, and the starch is corn starch.

[0015] The preparation method thereof comprises the following steps: (1) Starch gelatinization: Mix starch with 3 / 4 formula water, heat to 85℃, rotate at 800 rpm, stir for 20 min to obtain a uniform gelatinized liquid, cool to 60℃ and set aside; (2) Mix the composite oxidant and the remaining water evenly, stir at 800 rpm for 20 minutes to form an oxidant solution; (3) Place the gelatinized liquid in a constant temperature water bath at 60°C, add sodium hydroxide, rotate at 800 rpm, and stir for 10 minutes; (4) Add carboxymethyl cellulose, speed 1500 rpm, continue stirring for 8 minutes; (5) Slowly add the oxidant solution using a peristaltic pump for 15 min while maintaining the temperature at 60 °C. (6) After the addition is complete, the mixture is stirred at a speed of 1500 rpm for 10 min and then vacuum degassing is performed. The specific vacuum degassing temperature is -0.09 MPa for 15 min. (7) Filter and fill.

[0016] The ozone aging resistance of the above adhesives was measured, and the specific results are shown in Table 1.

[0017] Determination of resistance to ozone aging The test was carried out in accordance with the provisions of GB / T30778-2014, with the glue coating amount set to 10g / m2, and the sample was prepared. Then, according to the JF2051-2023 ozone aging test chamber calibration specification, the test chamber temperature was: 60±2℃, relative humidity: 75±5%, and ozone concentration was 300±60μmol / mol. The prepared sample was placed in the ozone aging test chamber and treated for one week. Then it was removed and its peel strength was measured.

[0018] Table 1 Determination results of the effects of different antioxidant raw material compositions on products ; As shown in Table 1, compared with Examples 1-4, Example 5 exhibited the lowest peel strength reduction, at 16.7%. This demonstrates that the composite antioxidant of the present invention effectively reduces oxidation reactions in high-humidity ozone environments, effectively improving the peel strength of the adhesive. The present invention utilizes a composite antioxidant to form a multi-level protective mechanism. Gallnut extract, rich in phenolic hydroxyl groups, quenches free radicals, interrupts oxidation chain reactions, and delays starch chain breakage. Antioxidant 168 decomposes hydroperoxides, inhibiting the thermo-oxidative degradation of starch at high temperatures, forming a synergistic redox system with the gallnut extract, enhancing antioxidant efficiency. Chitosan, through its amino groups, forms hydrogen bonds with starch hydroxyl groups, enhancing intermolecular forces. Its ability to chelate metal ions (such as Fe) blocks metal-catalyzed oxidation pathways. The interaction of these three ingredients creates a multi-layered protective mechanism, effectively enhancing the product's anti-aging properties.

[0019] Example 6-9: Results of the test on the effect of different antioxidant raw material ratios on the product The method is basically the same as Example 5, except that the composition ratios of different antioxidant raw materials are different, as shown in Table 2.

[0020] Table 2 Determination results of the effects of different antioxidant raw material composition ratios on products ; As shown in Table 2, the antioxidant used in the present invention has good resistance to wet heat ozone oxidation, and the peel strength reduction rate after aging is less than 18%.

[0021] Examples 10-15 investigate the effects of different starch adhesive raw material compositions on product performance An anti-aging and high-temperature resistant starch adhesive comprises starch, carboxymethyl cellulose, sodium hydroxide, sodium polyacrylate, nano-montmorillonite, calcium lignin sulfonate, a composite antioxidant, polyethylene glycol-600, and the balance is water.

[0022] The composite antioxidant consists of 4 parts of gallnut extract, 1687 parts of antioxidant, 26 parts of chitosan and 8 parts of preservative, calculated by weight.

[0023] The preservative is sodium benzoate and the starch is corn starch.

[0024] The preparation method thereof comprises the following steps: (1) Starch gelatinization: Mix starch with 3 / 4 formula water, heat to 85℃, rotate at 600 rpm, stir for 30 min to obtain a uniform gelatinized liquid, cool to 60℃ and set aside; (2) Mix polyethylene glycol-600 and the remaining water evenly, then add the composite oxidant, stir at 600 rpm for 30 minutes to form an oxidant solution; (3) Place the gelatinized liquid in a constant temperature water bath at 60°C, add sodium hydroxide, and stir at 600 rpm for 20 minutes; (4) Add sodium polyacrylate, react at 70°C, speed 600 rpm, and stir for 20 minutes; (5) Add carboxymethyl cellulose, nano-montmorillonite and calcium lignin sulfonate in sequence and continue stirring at 2000 rpm for 8 minutes; (6) Slowly add the oxidant solution using a peristaltic pump for 15 min while maintaining the temperature at 60 °C. (7) After the addition is complete, stir at 2000 rpm for 5 min and then vacuum degas; (8) Filter and bottle. The specific composition of raw materials is shown in Table 3.

[0025] Table 3 Raw material composition of different starch adhesives .

[0026] Adhesive product performance determination: 1. Determination of peel strength The test was carried out in accordance with the provisions of GB / T30778-2014, and the glue coating amount was set to 10g / m 2 , the test results are shown in Table 2.

[0027] 2. Determination of high and low temperature resistance Bond two sheets of glossy, high-quality, 90g standard double-sided coated paper, place the bonded papers in an environment with a temperature of 25±5°C and a humidity of 50±5% for curing for 24 hours, then place them in a 70°C oven for 8 hours. Observe that there is no bubbling or debonding at the interface of the bonded paper box, then peel them apart along the interface to see if the paper fibers are damaged. If the paper fibers are damaged, it indicates that the high-temperature resistance of the adhesive is qualified; if the paper fibers are not damaged, it indicates that the high-temperature resistance of the adhesive is unqualified.

[0028] Bond two sheets of glossy, high-quality, 90g standard double-sided coated paper, place the bonded papers in an environment with a temperature of 25±5°C and a humidity of 50±5% for 24 hours to cure, then place them in a refrigerator at -20°C for 16 hours. Observe the interface of the bonded paper box to see if there is bubbling or debonding. Peel the paper off along the interface to see if the paper fibers are damaged. If so, it indicates that the low-temperature resistance of the adhesive is qualified. If not, it indicates that the low-temperature resistance of the adhesive is unqualified.

[0029] 3. Determination of ozone aging resistance The test was carried out in accordance with the provisions of GB / T30778-2014, with the glue coating amount set to 10g / m2, and the sample was prepared. Then, according to the JF2051-2023 ozone aging test chamber calibration specification, the test chamber temperature was: 60±2℃, relative humidity: 75±5%, and ozone concentration was 300±60μmol / mol. The prepared sample was placed in the ozone aging test chamber and treated for one week. Then it was removed and its peel strength was measured.

[0030] The specific measurement results are shown in Table 4.

[0031] Table 4 The results of the influence of the raw material composition of different starch adhesives on product performance ; As shown in Table 4, compared with Examples 10-14, the peel strength of the adhesive prepared in Example 15 reached 532 N / m, showing good bonding strength and good high and low temperature resistance. The present invention effectively improves the high temperature resistance of the product by adding a high temperature resistant reinforcing component. The specific principle is as follows: Nano-montmorillonite is dispersed in the starch matrix to form physical crosslinks, inhibiting molecular chain slippage at high temperatures and raising the heat deformation temperature. Calcium lignin sulfonate: The sulfonic acid groups crosslink with the starch hydroxyl groups, enhancing hydrophobicity and reducing moisture-heat aging caused by water molecule penetration. Its phenolic hydroxyl groups provide additional UV shielding. Sodium polyacrylate forms an ionic crosslinked network with starch at high temperatures, synergistically thickening with carboxymethyl cellulose to prevent high-temperature sagging and maintain the integrity of the adhesive layer. Polyethylene glycol-600 is inserted between starch molecular chains, weakening hydrogen bond density, lowering the glass transition temperature, inhibiting high-temperature brittle cracking, and improving flexibility. This combination of ingredients effectively improves the product's high-temperature resistance.

[0032] Examples 16-20 investigate the effects of different starch adhesive raw material ratios on product performance It is basically the same as Example 15, except that the specific raw material ratios are different. The specific raw material composition ratios are shown in Table 5.

[0033] Table 5 Raw material composition ratio of different starch adhesives ; The prepared starch adhesive was tested, and the specific results are shown in Table 6.

[0034] Table 6 The results of the influence of the raw material composition ratio of different starch adhesives on product performance ;

[0035] As shown in Table 6, the adhesive prepared by the present invention does not bubble, debond, or damage fibers under high and low temperature environments, and has good bonding properties and high and low temperature resistance. The glass strength reduction rate before and after aging in a hot and humid ozone environment is less than 15%, and the adhesive has good anti-oxidation aging performance.

[0036] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An anti-aging and high temperature resistant starch adhesive, characterized by: Calculated by weight, the composition comprises 20-25% starch, 3-5% carboxymethyl cellulose, 1-2% sodium hydroxide, 1-2% sodium polyacrylate, 0.1-0.2% nano-montmorillonite, 0.3-0.8% calcium lignin sulfonate, 0.1-0.3% composite antioxidant, 0.5-1% polyethylene glycol-600, and the balance is water.

2. The anti-aging and high-temperature resistant starch adhesive according to claim 1, characterized in that: The composite antioxidant consists of 3-5 parts of gallnut extract, 6-10 parts of antioxidant 168, 20-30 parts of chitosan and 6-8 parts of preservative in parts by weight.

3. The anti-aging and high-temperature resistant starch adhesive according to claim 2, characterized in that: The preservative is benzoate or sorbate.

4. The anti-aging and high-temperature resistant starch adhesive according to any one of claims 1 to 3, characterized in that: The starch is one or a combination of more than one of corn starch, cassava starch, wheat starch and sweet potato starch.

5. The anti-aging and high-temperature resistant starch adhesive according to any one of claims 1 to 3, characterized in that: The molecular weight of the sodium polyacrylate is 4-6 million, and the particle size is 60-100 meshes.

6. The method for preparing an anti-aging and high-temperature resistant powder adhesive according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) Starch gelatinization: Mix starch with 3 / 4 formula water, heat to 70-85℃, rotate at 600-800 rpm, stir for 20-30 minutes to obtain a uniform gelatinized liquid, and cool to 60℃ for use; (2) Mix polyethylene glycol-600 and the remaining water evenly, then add the composite oxidant, rotate at 600-800 rpm, and stir for 20-30 minutes to form an oxidant solution; (3) Place the gelatinized liquid in a constant temperature water bath at 60°C, add sodium hydroxide, and stir at a speed of 600-800 rpm for 10-20 minutes; (4) Add sodium polyacrylate, react at 65-70°C, speed 600-800 rpm, and stir for 10-20 minutes; (5) Add carboxymethyl cellulose, nano-montmorillonite and calcium lignin sulfonate in sequence, and continue stirring at a speed of 1500-2000 rpm for 8-10 minutes; (6) Slowly add the oxidant solution using a peristaltic pump for 15 min while maintaining the temperature at 60 °C. (7) After the addition is complete, stir at a speed of 1500-2000 rpm for 5-10 minutes and then vacuum degas; (8) Filter and fill.

7. The preparation method according to claim 6, characterized in that: The vacuum degassing is specifically -0.09MPa, 10-20min.