Environmentally friendly water-based sealing adhesive and preparation method thereof

Abstract

The present invention relates to a kind of environment-friendly water-based sealing glue and preparation method thereof, adhesive field, according to weight parts, including 30-40 parts of aqueous tackifying emulsion;10-15 parts of xanthan gum;5-10 parts of guar gum;5-10 parts of lignocellulose;3-5 parts of tamarind gum;5-8 parts of sodium carboxymethyl starch;1-2 parts of nano-silicon dioxide;0.5-1 parts of citric acid;0.3-0.5 parts of potassium sorbate;0.5-1 parts of polyether-modified silicone oil;60-80 parts of deionized water.The environment-friendly water-based sealing glue of the present invention contains multiple tackifying components such as aqueous tackifying emulsion, xanthan gum, guar gum, lignocellulose and tamarind gum, and these components cooperate with each other to form a complex viscous network structure, can enhance the bonding force between sealing glue and different packaging materials, make it have good bonding, high and low temperature resistance and aging resistance effect on multiple substrates such as paper, plastic, etc.

Description

Technical Field

[0001] The invention relates to an environmentally friendly water-based sealing adhesive and a preparation method thereof, and belongs to the field of adhesives. Background Art

[0002] Sealant is an adhesive used to bond material edges or seal package openings. It is widely used in the packaging, printing, textile, and paper industries. Depending on the base material and performance, it can be categorized into solvent-based and water-based sealants. Water-based sealants are environmentally friendly adhesives that use water as a dispersion medium. They are non-toxic and pollution-free and are gradually replacing oil-based sealants. Many water-based sealants currently available on the market are primarily made from chemically synthesized raw materials, such as acrylate-vinyl acetate copolymer emulsions, polyvinyl acetate emulsions, and styrene-butadiene rubber emulsions. These raw materials are mostly derived from non-renewable resources such as petroleum, and their large-scale use can lead to resource depletion. Furthermore, some water-based sealants made from chemical raw materials are difficult to degrade in the natural environment, potentially causing environmental pollution and impacting the balance of the ecosystem. There are also some sealants on the market that are primarily made from plant-based raw materials, which are both recyclable and biodegradable. Compared with chemical raw materials, sealants made from plant materials also have some problems: (1) The bonding strength is relatively low, especially in some special materials or complex environments, the bonding effect may be poor; (2) Sealing glues made mainly from plant materials may be prone to performance degradation and aging in complex environments such as long-term or high-intensity water contact and ultraviolet radiation, resulting in debonding or failure of the seal; (3) The natural ingredients in plant materials may be more sensitive to environmental conditions such as temperature and humidity, and are easily affected by moisture, mold or deterioration, affecting the performance and service life of the glue. Therefore, it is of great significance to develop environmentally friendly water-based sealants rich in plant materials. Summary of the Invention

[0003] The present invention provides an environmentally friendly water-based sealing adhesive and a preparation method thereof, which solves the problems that the existing water-based sealing adhesive is mainly made of chemically synthesized raw materials, may cause environmental pollution, and affect the balance of the ecosystem.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] An environmentally friendly water-based sealing adhesive comprises, by weight, 30-40 parts of a water-based tackifying emulsion; 10-15 parts of xanthan gum; 5-10 parts of guar gum; 5-10 parts of lignocellulose; 3-5 parts of tamarind gum; 5-8 parts of sodium carboxymethyl starch; 1-2 parts of nano-silicon dioxide; 0.5-1 part of citric acid; 0.3-0.5 part of potassium sorbate; 0.5-1 part of polyether-modified silicone oil; and 60-80 parts of deionized water.

[0006] Furthermore, preferably, the solid content of the aqueous thickening emulsion is 45-50%, and the viscosity is 2000-4000 cPa·s.

[0007] Furthermore, preferably, the average fiber length of the lignocellulose is 0.3-0.8 mm, and the fiber width is 20-30 μm.

[0008] Furthermore, preferably: the particle size of the nano-silicon dioxide is 10-20nm, and the specific surface area is 100-200m 2 / g.

[0009] The preparation method of the environmentally friendly water-based sealing adhesive of the present invention comprises the following steps:

[0010] (1) Stir wood cellulose, 30-40 parts of deionized water and polyether-modified silicone oil to form a suspension;

[0011] (2) Dispersing xanthan gum and guar gum in the remaining deionized water to form a transparent glue solution;

[0012] (3) combining the suspension of step (1) and the transparent glue of step (2), adding tamarind gum and sodium carboxymethyl starch in sequence, and stirring evenly;

[0013] (4) Slowly add nano-silica to the solution of step (3) at a speed of 2000-3000 rpm for 20-30 min;

[0014] (5) adding aqueous thickening emulsion, rotating at 2000-3000 rpm, and processing for 20-30 min to obtain a mixed emulsion;

[0015] (6) homogenizing the mixed emulsion of step (5);

[0016] (7) After homogenization, add citric acid to adjust the pH of the system to 5.0-6.0, add potassium sorbate, and stir to dissolve;

[0017] (8) Degassing, then filtering with a 200-300 mesh filter to remove impurities, and cooling to room temperature to obtain the product.

[0018] Furthermore, preferably, the stirring in step (1) is specifically: a rotation speed of 800-1000 rpm, and stirring for 20-30 minutes.

[0019] Furthermore, preferably, the stirring in step (3) is specifically: stirring at 50-55°C and a rotation speed of 600-800 rpm for 30-40 minutes.

[0020] Furthermore, preferably, the homogenization treatment in step (6) is specifically as follows: pressure 100-120 MPa, 2 cycles, to ensure that the emulsion particle size is ≤1 μm.

[0021] Beneficial effects of the present invention:

[0022] The environmentally friendly water-based sealing adhesive of the present invention contains multiple thickening ingredients such as water-based thickening emulsion, xanthan gum, guar gum, wood cellulose and tamarind gum. These ingredients work together to form a complex viscous network structure, which can enhance the adhesion between the sealing adhesive and different packaging materials, so that the sealing adhesive has good adhesion, high and low temperature resistance and aging resistance to various substrates such as paper and plastic. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are excluded.

[0024] The raw materials used in the following examples are as follows:

[0025] The water-based thickening emulsion used is thickening emulsion SX-10, a yellow-white liquid with a viscosity of 2000-4000 cPa·s (25°C); solid content: 50%±2; pH value: 6-7;

[0026] Xanthan gum: content ≥95%, 800 mesh;

[0027] Guar gum: content ≥95%, 100 mesh;

[0028] The wood cellulose is hydroxyethyl cellulose, with a content of ≥99% and a density of 1 (g / cm 3 );

[0029] Tamarind gum: content ≥99%, 80-100 mesh;

[0030] Nano-silicon dioxide, content ≥99%, particle size 10-20nm, specific surface area 100-200m 2 / g;

[0031] The polyether modified silicone oil is QC1011 polyether modified silicone oil, which is a light yellow, easy-flowing, transparent and uniform oil with a viscosity (25°C): 1000-2000mPa·s, a specific gravity (25°C): 1.011-1.085, and an active ingredient: 100%.

[0032] There are no special requirements for other raw materials, as long as they meet the relevant industrial raw material standards.

[0033] Example 1

[0034] An environmentally friendly water-based sealing adhesive comprises, by weight, 35 parts of a water-based tackifying emulsion, 12 parts of xanthan gum, 8 parts of guar gum, 7 parts of wood cellulose, 4 parts of tamarind gum, 6 parts of sodium carboxymethyl starch, 1.5 parts of nano-silicon dioxide, 0.6 parts of citric acid, 0.4 parts of potassium sorbate, 0.8 parts of polyether-modified silicone oil, and 70 parts of deionized water.

[0035] The preparation method thereof comprises the following steps:

[0036] (1) Add wood cellulose and 30 parts of deionized water into a high-speed disperser, add polyether-modified silicone oil, and stir at 800 rpm for 30 minutes to form a uniform suspension to prevent fiber agglomeration;

[0037] (2) Disperse xanthan gum and guar gum in the remaining deionized water, keep the temperature at 40-45°C, and stir at 800 rpm for 30 min to allow them to fully swell and form a transparent glue solution;

[0038] (3) The suspension of step (1) and the transparent glue of step (2) were combined, and tamarind gum and sodium carboxymethyl starch were added in sequence, and stirred at 50-55°C and 800 rpm for 30 min;

[0039] (4) Slowly add nano-silica to the above system and switch to a high shear homogenizer at a speed of 2000 rpm for 30 min to ensure that the nanoparticles are evenly dispersed;

[0040] (5) Adding aqueous thickening emulsion, rotating at 2000 rpm for 30 min to obtain a mixed emulsion;

[0041] (6) Transfer the mixed emulsion from step (5) to a high-pressure homogenizer at a pressure of 100 MPa and cycle twice to ensure that the emulsion particle size is ≤1 μm;

[0042] (7) Add citric acid to adjust the pH of the system to 5.0-6.0, add potassium sorbate, and continue stirring at 300 rpm for 10 minutes until dissolved;

[0043] (8) Degassing, then filtering with a 200-mesh filter to remove impurities, and cooling to room temperature to obtain the product.

[0044] Example 2

[0045] An environmentally friendly water-based sealing adhesive comprises, by weight, 30 parts of a water-based tackifying emulsion, 10 parts of xanthan gum, 10 parts of guar gum, 8 parts of wood cellulose, 3 parts of tamarind gum, 5 parts of sodium carboxymethyl starch, 1.5 parts of nano-silicon dioxide, 0.5 parts of citric acid, 0.3 parts of potassium sorbate, 0.5 parts of polyether-modified silicone oil, and 60 parts of deionized water.

[0046] The preparation method thereof comprises the following steps:

[0047] (1) Add wood cellulose and 30 parts of deionized water into a high-speed disperser, add polyether-modified silicone oil, and stir at a speed of 1000 rpm for 20 minutes to form a uniform suspension to prevent fiber agglomeration;

[0048] (2) Disperse xanthan gum and guar gum in the remaining deionized water, keep the temperature at 40-45°C, rotate at 1000 rpm, and stir for 20 min to allow them to fully swell and form a transparent glue solution;

[0049] (3) The suspension of step (1) and the transparent glue of step (2) were combined, and tamarind gum and sodium carboxymethyl starch were added in sequence, and stirred at 50-55°C and 800 rpm for 30 min;

[0050] (4) Slowly add nano-silica to the above system and switch to a high shear homogenizer at a speed of 3000 rpm for 20 min to ensure that the nanoparticles are evenly dispersed;

[0051] (5) Adding aqueous thickening emulsion, rotating at 3000 rpm for 20 min to obtain a mixed emulsion;

[0052] (6) Transfer the mixed emulsion from step (5) to a high-pressure homogenizer at a pressure of 120 MPa and cycle twice to ensure that the emulsion particle size is ≤1 μm;

[0053] (7) Add citric acid to adjust the pH of the system to 5.0-6.0, add potassium sorbate, and continue stirring at 300 rpm for 5 minutes until dissolved;

[0054] (8) Degassing, then filtering with a 200-mesh filter to remove impurities, and cooling to room temperature to obtain the product.

[0055] Example 3

[0056] An environmentally friendly water-based sealing adhesive comprises, by weight, 38 parts of a water-based tackifying emulsion, 15 parts of xanthan gum, 5 parts of guar gum, 5 parts of lignocellulose, 5 parts of tamarind gum, 7 parts of sodium carboxymethyl starch, 2 parts of nano-silicon dioxide, 0.7 parts of citric acid, 0.5 parts of potassium sorbate, 0.6 parts of polyether-modified silicone oil, and 75 parts of deionized water.

[0057] The preparation method thereof comprises the following steps:

[0058] (1) Add wood cellulose and 35 parts of deionized water into a high-speed disperser, add polyether-modified silicone oil, and stir at 800 rpm for 30 minutes to form a uniform suspension to prevent fiber agglomeration;

[0059] (2) Disperse xanthan gum and guar gum in the remaining deionized water, keep the temperature at 40-45°C, rotate at 800 rpm, and stir for 20-30 min to allow them to fully swell and form a transparent glue solution;

[0060] (3) The suspension of step (1) and the transparent glue of step (2) were combined, and tamarind gum and sodium carboxymethyl starch were added in sequence. The mixture was stirred at 50-55°C and 700 rpm for 35 min.

[0061] (4) Slowly add nano-silica to the above system and switch to a high shear homogenizer at a speed of 2500 rpm for 30 min to ensure that the nanoparticles are evenly dispersed;

[0062] (5) Adding aqueous thickening emulsion, rotating at 2500 rpm for 30 min to obtain a mixed emulsion;

[0063] (6) Transfer the mixed emulsion from step (5) to a high-pressure homogenizer at a pressure of 110 MPa and cycle twice to ensure that the emulsion particle size is ≤1 μm;

[0064] (7) Add citric acid to adjust the pH of the system to 5.0-6.0, add potassium sorbate, and continue stirring at 300 rpm for 10 min until dissolved;

[0065] (8) Degassing, then filtering with a 300-mesh filter to remove impurities, and cooling to room temperature to obtain the product.

[0066] Example 4

[0067] An environmentally friendly water-based sealing adhesive comprises, by weight, 40 parts of a water-based tackifying emulsion, 12 parts of xanthan gum, 6 parts of guar gum, 6 parts of wood cellulose, 4 parts of tamarind gum, 6 parts of sodium carboxymethyl starch, 1 part of nano-silicon dioxide, 1 part of citric acid, 0.4 parts of potassium sorbate, 1 part of polyether-modified silicone oil, and 80 parts of deionized water.

[0068] The preparation method thereof comprises the following steps:

[0069] (1) Add wood cellulose and 40 parts of deionized water into a high-speed disperser, add polyether-modified silicone oil, and stir at 800 rpm for 30 minutes to form a uniform suspension to prevent fiber agglomeration;

[0070] (2) Disperse xanthan gum and guar gum in the remaining deionized water, keep the temperature at 40-45°C, rotate at 800 rpm, and stir for 30 min to allow them to fully swell and form a transparent glue solution;

[0071] (3) The suspension of step (1) and the transparent glue of step (2) were combined, and tamarind gum and sodium carboxymethyl starch were added in sequence, and stirred at 50-55°C and 800 rpm for 40 min;

[0072] (4) Slowly add nano-silica to the above system and switch to a high shear homogenizer at a speed of 2000 rpm for 30 min to ensure that the nanoparticles are evenly dispersed;

[0073] (5) Adding aqueous thickening emulsion, rotating at 2000 rpm for 30 min to obtain a mixed emulsion;

[0074] (6) Transfer the mixed emulsion from step (5) to a high-pressure homogenizer at a pressure of 120 MPa and cycle twice to ensure that the emulsion particle size is ≤1 μm;

[0075] (7) Add citric acid to adjust the pH of the system to 5.0-6.0, add potassium sorbate, and continue stirring at 300 rpm for 5 minutes until dissolved;

[0076] (8) Degassing, then filtering with a 300-mesh filter to remove impurities, and cooling to room temperature to obtain the product.

[0077] Comparative Examples 1-6 investigate the effects of plant adhesives on sealing adhesives

[0078] An environmentally friendly water-based sealing adhesive comprises, by weight, 35 parts of an aqueous tackifying emulsion, 0-15 parts of xanthan gum, 0-10 parts of guar gum, 0-10 parts of lignocellulose, 0-5 parts of tamarind gum, 6 parts of sodium carboxymethyl starch, 1.5 parts of nano-silicon dioxide, 0.6 parts of citric acid, 0.4 parts of potassium sorbate, 0.8 parts of polyether-modified silicone oil, and 70 parts of deionized water. The preparation method is the same as that of Example 1.

[0079] The specific ratios of xanthan gum, guar gum, wood cellulose and tamarind gum are shown in Table 1.

[0080] Table 1 Raw material ratios of different embodiments

[0081] ;

[0082] The performance indicators of Example 1 and Comparative Examples 1-6 were measured using the following methods:

[0083] 1. Viscosity measurement

[0084] The test was carried out in accordance with the test method in GB / T2794-2013 "Determination of viscosity of adhesives" under the following test conditions: temperature 25°C, rotation speed 6 r / min.

[0085] 2. Determination of peel strength

[0086] 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.

[0087] 3. Determination of high and low temperature resistance

[0088] Glue two sheets of high-quality 90g standard double-sided coated paper together, place the bonded papers in an environment with a temperature of 25±5℃ and a humidity of 50±5% for curing for 24 hours, then place them in a 70℃ oven. After 8 hours, observe whether there are bubbles or debonding at the interface of the bonded paper box, then peel them apart along the interface and observe whether the paper fibers are damaged. If the paper fibers are damaged, it indicates that the high-temperature resistance of the prepared box-pasting glue is qualified; if the paper fibers are not damaged, it indicates that the high-temperature resistance of the prepared box-pasting glue is unqualified.

[0089] Two sheets of high-quality glossy double-sided coated paper of 90g are glued together. After curing for 24 hours in an environment with a temperature of 25±5℃ and a humidity of 50±5%, the glued papers are placed in a refrigerator at -20℃. After 16 hours, the interface of the glued paper box is observed to see if there is bubbling or debonding. The paper is peeled off along the interface to see if the paper fibers are damaged. If the paper fibers are damaged, it indicates that the low-temperature resistance of the glue is qualified. If the paper fibers are not damaged, it indicates that the low-temperature resistance of the glue is unqualified.

[0090] 4. Anti-aging tension and compression cycle durability

[0091] The test was carried out in accordance with the provisions of GB / T41753-2022 Test method for tensile and compressive cycle durability of sealants under artificial climate aging. A xenon arc lamp was used for the aging test. One cycle was every 7 days, and the light transmittance period of the specimen was recorded.

[0092] The specific test results are shown in Table 2.

[0093] Table 2 Test results of sealing glue composed of different raw materials

[0094] ;

[0095] As can be seen from Table 2, the present invention combines an aqueous thickening emulsion with a variety of plant extracts. The aqueous thickening emulsion serves as a basic film-forming substance to provide initial viscosity, while plant polysaccharide thickeners such as xanthan gum and guar gum form a viscous network. The combination of the two significantly improves the bonding strength and durability of the sealing glue; nano-silica and plant extracts synergistically improve the water resistance and stability of the sealing glue, while enhancing the mechanical properties of the colloid to prevent cracking and falling off; citric acid and potassium sorbate inhibit microbial growth, extend the shelf life of the glue, and ensure the quality stability of the sealing glue during storage and use; polyether-modified silicone oil reduces the surface tension of the glue, improves the rheological properties, and enables it to spread more evenly during the coating process, thereby improving the construction performance and appearance quality.

[0096] Comparative Example 1 removed xanthan gum and replaced it with guar gum. Xanthan gum is the primary thickener in the system. The pseudoplasticity and network structure of its molecular chains synergize with guar gum to form a three-dimensional network, effectively improving the viscosity and peel strength of the sealing adhesive. After removing xanthan gum, the system viscosity decreased by 27%, fluidity increased, but initial tack was insufficient, and peel strength decreased by 35%. This was primarily due to the lack of synergy between xanthan gum and guar gum, which weakened permeability to the paper-plastic interface and significantly reduced peel strength.

[0097] Comparative Example 2 removed guar gum and replaced it with xanthan gum. Guar gum and xanthan gum synergistically form a film, improving water resistance. The lack of guar gum impairs film-forming properties and reduces water resistance, which in turn reduces the sealant's high and low temperature resistance. It also causes debonding at high temperatures and bubbling and debonding at low temperatures. The main reason is that guar gum lacks the helical structural support of xanthan gum, making it unable to form a dynamic network and resulting in a simplification of mechanical properties.

[0098] Comparative Example 3 removed lignocellulose and replaced it with xanthan gum. The cellulose chains of lignocellulose provide rigid support, complementing the flexible chains of tamarind gum to form a high-strength network. After removal, the sealing adhesive's viscosity, peel strength, and aging cycle resistance were significantly reduced, particularly from 12 cycles to 9.

[0099] Comparative Example 4: Tamarind gum was removed and replaced with xanthan gum. The acidic polysaccharide structure of tamarind gum forms hydrogen bonds with the hydroxyl groups of lignocellulose, effectively improving the sealant's high- and low-temperature stability and aging resistance. However, the removal of the tamarind gum resulted in a loss of hydrophobic groups, which led to easy delamination of the film, the formation of craters during coating, and an uneven surface. This significantly reduced its high- and low-temperature resistance and aging cycle resistance. In high- and low-temperature resistance tests, problems such as bubbling, delamination, and fiber damage were observed.

[0100] Comparative Example 5 removed xanthan gum and guar gum and used an aqueous thickening emulsion. Xanthan gum and guar gum form a viscous network, synergistically thickening the adhesive, significantly increasing the adhesive's viscosity and stability, while preventing delamination. After removing these, the adhesive's performance, including viscosity and high- and low-temperature stability, was significantly reduced.

[0101] Comparative Example 6 removed the lignocellulose and tamarind gum and used an aqueous thickening emulsion. Lignocellulose and tamarind gum provide fiber support and enhance the viscous network, synergistically improving the sealant's peel strength, high- and low-temperature stability, and aging resistance. After removal, the sealant's peel strength, high- and low-temperature stability, and aging resistance were significantly reduced.

[0102] 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 environmentally friendly water-based sealing adhesive, characterized in that: The invention comprises, by weight, 30-40 parts of aqueous thickening emulsion, 10-15 parts of xanthan gum, 5-10 parts of guar gum, 5-10 parts of wood cellulose, 3-5 parts of tamarind gum, 5-8 parts of sodium carboxymethyl starch, 1-2 parts of nano-silicon dioxide, 0.5-1 part of citric acid, 0.3-0.5 part of potassium sorbate, 0.5-1 part of polyether modified silicone oil and 60-80 parts of deionized water.

2. The environmentally friendly water-based sealing adhesive according to claim 1, characterized in that: The solid content of the aqueous thickening emulsion is 45-50%, and the viscosity is 2000-4000 cpa·s.

3. The environmentally friendly water-based sealing adhesive according to claim 1, characterized in that: The average fiber length of the wood cellulose is 0.3-0.8 mm, and the fiber width is 20-30 μm.

4. The environmentally friendly water-based sealing adhesive according to claim 1, characterized in that: The particle size of the nano-silicon dioxide is 10-20 nm, and the specific surface area is 100-200 m 2 / g.

5. A method for preparing the environmentally friendly water-based sealing adhesive according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) Stir wood cellulose, 30-40 parts of deionized water and polyether-modified silicone oil to form a suspension; (2) Dispersing xanthan gum and guar gum in the remaining deionized water to form a transparent glue solution; (3) combining the suspension of step (1) and the transparent glue of step (2), adding tamarind gum and sodium carboxymethyl starch in sequence, and stirring evenly; (4) Slowly add nano-silica to the solution of step (3) at a speed of 2000-3000 rpm for 20-30 min; (5) adding aqueous thickening emulsion, rotating at 2000-3000 rpm, and processing for 20-30 min to obtain a mixed emulsion; (6) homogenizing the mixed emulsion of step (5); (7) After homogenization, add citric acid to adjust the pH of the system to 5.0-6.0, add potassium sorbate, and stir to dissolve; (8) Degassing, then filtering with a 200-300 mesh filter to remove impurities, and cooling to room temperature to obtain the product.

6. The method for preparing the environmentally friendly water-based sealing adhesive according to claim 5, characterized in that: The stirring in step (1) is specifically as follows: a rotation speed of 800-1000 rpm, and stirring for 20-30 minutes.

7. The method for preparing the environmentally friendly water-based sealing adhesive according to claim 5, characterized in that: The stirring in step (3) is specifically as follows: stirring at 50-55°C and a rotation speed of 600-800 rpm for 30-40 minutes.

8. The method for preparing the environmentally friendly water-based sealing adhesive according to claim 5, wherein: The homogenization treatment in step (6) is specifically as follows: pressure 100-120 MPa, 2 cycles, and ensuring that the emulsion particle size is ≤1 μm.