A modified starch-based glass wool adhesive, its preparation method and application

Abstract

This invention provides a modified starch-based glass wool adhesive, its preparation method, and its application, belonging to the field of glass wool technology. The method includes: using natural starch as raw material, reducing its molecular weight through inorganic acid hydrolysis, introducing carboxyl groups through oxidation with an oxidant, and esterifying to introduce a hydrophilic / hydrophobic balance, thereby obtaining modified starch. The modified starch exhibits significantly improved solubility in cold water. This invention further combines the modified starch with sodium hypophosphite, additives, and water, significantly reducing the activation energy of the crosslinking reaction and increasing the crosslinking and curing speed. By introducing a composite modification method, this invention significantly reduces the amount of foam generated during high-temperature curing, effectively avoiding the defect of uneven glass wool density caused by bubbles. This invention features a simple process, requires no heating for gelatinization, has low energy consumption, uses renewable raw materials, and releases no formaldehyde, making it suitable for large-scale production of green and environmentally friendly glass wool adhesives.

Description

Technical Field

[0001] This invention relates to the field of glass wool technology, specifically to a modified starch-based glass wool binder, its preparation method, and its application. Background Technology

[0002] Glass wool possesses excellent sound absorption, sound insulation, and thermal insulation properties, and is widely used in industrial and civil fields. A certain amount of binder needs to be added during the glass wool molding process. Currently, the commonly used glass wool binders on the market are mainly phenolic resin and melamine resin. However, phenolic resin and melamine resin have drawbacks such as formaldehyde release and non-renewable raw materials. With the improvement of people's living standards and increased health awareness, the use of glass wool containing formaldehyde is restricted. New bio-based binders use renewable biomass as raw materials and do not release formaldehyde or produce harmful gases, thus attracting widespread attention from researchers.

[0003] Starch is a widely available, renewable, inexpensive, safe, and non-toxic high-molecular-weight polysaccharide polymer, making it an ideal material to replace petrochemical-based binders. However, using natural starch directly as a glass wool binder presents the following problems: 1) It is insoluble in cold water and requires heating for gelatinization, resulting in a complex process; 2) It has low hydroxyl reactivity, leading to slow cross-linking and curing speeds, making it unsuitable for the high-speed curing required in glass wool production lines (typically requiring completion within 2-5 minutes); 3) It has poor water resistance after curing, easily swelling upon contact with water, causing the glass wool to absorb moisture and deform; 4) It easily generates a large number of air bubbles during high-temperature curing, resulting in uneven density of the glass wool.

[0004] While there are existing methods for modifying starch (such as oxidation, esterification, etherification, etc.), most of them are for the food, papermaking, construction, and textile industries, and have not been optimized for the special requirements of glass wool curing process (rapid cross-linking, high water resistance, low foaming). Summary of the Invention

[0005] In view of this, the present invention provides a method for preparing a modified starch-based glass wool adhesive, comprising the following steps:

[0006] (1) Mix natural starch and inorganic acid in a certain proportion to undergo hydrolysis reaction. After the reaction is completed, neutralize with alkali, filter and dry to obtain acid hydrolyzed starch;

[0007] (2) Add water to the acid-hydrolyzed starch to prepare an acid-hydrolyzed starch slurry. Adjust the pH to 8.0~9.5 with alkali. Add an oxidant to carry out an oxidation reaction. After the reaction is completed, filter, wash and dry to obtain oxidized starch.

[0008] (3) Dissolve the oxidized starch in the reaction medium, add esterifying agent and catalyst, carry out esterification reaction, neutralize with dilute hydrochloric acid after the reaction, filter, wash and dry to obtain pretreated modified starch;

[0009] (4) The pretreated modified starch is mixed with sodium hypophosphite, additives and water in a certain proportion, the pH is adjusted to 4.0~6.0, and the mixture is stirred evenly to obtain glass wool adhesive.

[0010] Furthermore, the inorganic acid in step (1) is selected from any one of hydrochloric acid, sulfuric acid, and nitric acid; the natural starch is selected from any one of corn starch, potato starch, and sweet potato starch.

[0011] Furthermore, the solid-liquid ratio of the natural starch and inorganic acid in step (1) is 1:2 to 1:4.

[0012] Furthermore, the hydrolysis temperature in step (1) is 40~70℃, and the hydrolysis time is 0.5~3 hours; the drying process includes vacuum drying at 40℃ until the moisture content is <10%.

[0013] Furthermore, the mass concentration of the acid-hydrolyzed starch slurry in step (2) is 30%~45%.

[0014] Furthermore, the oxidant in step (2) is sodium hypochlorite; the process conditions for the oxidation reaction include: temperature 35~50℃, time 1~3 hours.

[0015] Furthermore, the reaction medium in step (3) includes any one of isopropanol or acetone; the esterifying agent is selected from any one of acetic anhydride, propionic anhydride, succinic anhydride, and octenyl succinic anhydride; the amount of the esterifying agent is 5% to 20% of the dry starch mass.

[0016] Furthermore, the process conditions for the esterification reaction in step (3) include: temperature 40~60℃, time 1~4 hours.

[0017] Furthermore, the catalyst in step (3) is selected from either pyridine or 4-dimethylaminopyridine (DMAP); the amount of catalyst used is 0.5% to 1% of the dry starch mass.

[0018] Furthermore, in step (4), the mass ratio of the pretreated modified starch, sodium hypophosphite, additives, and water is 100:(5~20):(3-8):(200~400).

[0019] Furthermore, the preparation method of the auxiliary agent is as follows:

[0020] (1) Under the protection of inert gas, myristic acid, ethylenediamine and cyclohexane are mixed and heated to 110-170℃ for 1-3h. After the reaction is completed, the mixture is discharged at room temperature to obtain intermediate product a.

[0021] (2) Under the protection of an inert gas, N,N-dimethylthiourea and cyclohexane are added to the intermediate product a, and the temperature is raised to 80-90℃ and reacted for 2-4.5h to obtain intermediate product b;

[0022] (3) Under the protection of an inert gas, add cyclohexane to the intermediate product b, heat to 110-150℃, slowly add isophorone diisocyanate to the system, keep the reaction at the temperature for 4-5 hours, and then add intermediate product c.

[0023] (4) Under the protection of an inert gas, the intermediate product c, bromoacetic acid and methanol are mixed and heated to 40-55℃ for 1-2 hours. After the reaction is completed, the mixture is cooled to room temperature and excess solvent is removed by vacuum evaporation to obtain the auxiliary agent.

[0024] Furthermore, in the preparation of the auxiliary agent, the molar ratio of myristic acid and ethylenediamine in step (1) is 2:1; the amount of cyclohexane added is 2-5 times (mL / g) the mass of myristic acid.

[0025] Furthermore, in the preparation of the auxiliary agent, the molar ratio of intermediate product a and N,N-dimethylthiourea in step (2) is 1:3; the amount of cyclohexane added is 1-3 times (mL / g) the mass of myristic acid.

[0026] Furthermore, in the preparation of the auxiliary agent, the molar ratio of intermediate product b and isophorone diisocyanate in step (3) is 1.5:1; the amount of cyclohexane added is 2-5 times (mL / g) the mass of intermediate product b.

[0027] Furthermore, in the preparation of the auxiliary agent, the molar ratio of intermediate product c and bromoacetic acid in step (4) is 1:3.5; the amount of methanol added is 5-8 times (mL / g) the mass of intermediate product c.

[0028] The present invention also provides a modified starch-based glass wool adhesive prepared according to the method, and the application of the modified starch-based glass wool adhesive in the field of glass wool.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. This invention reduces the molecular weight of starch through acid hydrolysis, introduces carboxyl groups through oxidation, and introduces hydrophilic / hydrophobic balance through esterification, which significantly improves the solubility of modified starch in cold water at 25°C. Moreover, it eliminates the need for heating and gelatinization, thereby reducing energy consumption, simplifying the process, and improving economic benefits.

[0031] 2. This invention significantly improves the crosslinking activity of starch and increases the crosslinking and curing speed. The modified starch-based glass wool adhesive prepared can adapt to the high-speed curing of glass wool production lines.

[0032] 3. This invention introduces hydrophobic groups through esterification reaction, which significantly improves the water resistance of the adhesive. After curing, the water repellency of the glass wool is ≥98%, and it does not fall off after boiling in water for 2 hours.

[0033] 4. This invention significantly reduces the amount of foam generated during high-temperature curing (the foaming index drops from 9 to 2) by combining composite modification methods with the introduction of specific additives, which can effectively avoid the defect of uneven density of glass wool caused by bubbles. Detailed Implementation

[0034] This invention provides a method for preparing a modified starch-based glass wool adhesive, comprising the following steps:

[0035] (1) Mix natural starch and inorganic acid in a certain proportion to undergo hydrolysis reaction. After the reaction is completed, neutralize with alkali, filter and dry to obtain acid hydrolyzed starch;

[0036] (2) Add water to the acid-hydrolyzed starch to prepare an acid-hydrolyzed starch slurry. Adjust the pH to 8.0~9.5 with alkali. Add an oxidant to carry out an oxidation reaction. After the reaction is completed, filter, wash and dry to obtain oxidized starch.

[0037] (3) Dissolve the oxidized starch in the reaction medium, add esterifying agent and catalyst, carry out esterification reaction, neutralize with dilute hydrochloric acid after the reaction, filter, wash and dry to obtain pretreated modified starch;

[0038] (4) The pretreated modified starch is mixed with sodium hypophosphite, additives and water in a certain proportion, the pH is adjusted to 4.0~6.0, and the mixture is stirred evenly to obtain glass wool adhesive.

[0039] In some embodiments of the present invention, the inorganic acid in step (1) is selected from any one of hydrochloric acid, sulfuric acid, and nitric acid. Preferably, the inorganic acid in step (1) is hydrochloric acid, and the concentration of the hydrochloric acid is 0.01~0.1 mol / L.

[0040] In some embodiments of the present invention, the natural starch is selected from any one of corn starch, potato starch, and sweet potato starch. Preferably, the natural starch is corn starch; more preferably, the natural starch is waxy corn starch with an amylose content of <5%.

[0041] In some embodiments of the present invention, the solid-liquid ratio of the natural starch and inorganic acid in step (1) is 1:2 to 1:4.

[0042] In some embodiments of the present invention, the hydrolysis temperature in step (1) is 40~70°C and the hydrolysis time is 0.5~3 hours.

[0043] In some embodiments of the present invention, after the reaction in step (1) is completed, the solution is neutralized with 1 mol / L NaOH to pH = 6.5~7.0.

[0044] In some embodiments of the present invention, the drying process in step (1) includes vacuum drying at 40°C to a moisture content of <10%.

[0045] In some embodiments of the present invention, step (1) controls the degree of hydrolysis so that the weight-average molecular weight (M_w) of starch is reduced to 5 × 10⁻⁶. 4 ~2×10 5 g / mol, polydispersity index (PDI) ≤ 2.5.

[0046] In some embodiments of the present invention, the mass concentration of the acid-hydrolyzed starch slurry in step (2) is 30% to 45%.

[0047] In some embodiments of the present invention, the oxidant in step (2) is sodium hypochlorite.

[0048] In some embodiments of the present invention, the process conditions for the oxidation reaction in step (2) include: temperature 35~50℃, time 1~3 hours.

[0049] In some embodiments of the present invention, after the reaction in step (2) is completed, excess hypochlorous acid is reduced with sodium bisulfite (potassium iodide test paper does not turn blue), filtered, washed until no chloride ions are present, and dried to obtain oxidized starch.

[0050] In some embodiments of the present invention, step (2) controls the carboxyl content to be between 0.5% and 2.5% (mole fraction).

[0051] In some embodiments of the present invention, the reaction medium in step (3) includes either isopropanol or acetone.

[0052] In some embodiments of the present invention, the preparation method of the modified starch-based glass wool adhesive includes the following steps:

[0053] (1) Mix natural starch and inorganic acid in a certain proportion to undergo hydrolysis reaction. After the reaction is completed, neutralize with alkali, filter and dry to obtain acid hydrolyzed starch;

[0054] (2) Add water to the acid hydrolyzed starch to prepare an acid hydrolyzed starch slurry. Adjust the pH to 8.0~9.5 with alkali. Add an oxidant to carry out an oxidation reaction. When the reaction is halfway through, add an esterifying agent and a catalyst directly to carry out an esterification reaction. After the reaction is completed, neutralize with dilute hydrochloric acid, filter, wash and dry to obtain pretreated modified starch.

[0055] (3) The pretreated modified starch is mixed with sodium hypophosphite, additives and water in a certain proportion, the pH is adjusted to 4.0~6.0, and the mixture is stirred evenly to obtain glass wool adhesive.

[0056] The one-step oxidation-esterification composite modification provided by this invention can reduce intermediate drying steps and is suitable for industrial production.

[0057] In some embodiments of the present invention, the esterifying agent is selected from any one of acetic anhydride, propionic anhydride, succinic anhydride, and octenyl succinic anhydride.

[0058] In some embodiments of the present invention, the amount of esterifying agent used is 5% to 20% of the dry weight of starch.

[0059] In some embodiments of the present invention, the process conditions for the esterification reaction include: temperature 40~60°C, time 1~4 hours.

[0060] In some embodiments of the present invention, the catalyst is selected from either pyridine or 4-dimethylaminopyridine (DMAP).

[0061] In some embodiments of the present invention, the amount of catalyst used is 0.5% to 1% of the dry weight of starch.

[0062] In some embodiments of the present invention, the degree of esterification substitution (DS) is controlled to be between 0.05 and 0.4.

[0063] In some embodiments of the present invention, the mass ratio of the pretreated modified starch, sodium hypophosphite, additives, and water is 100:(5~20):(3-8):(200~400).

[0064] The present invention also provides a modified starch-based glass wool adhesive prepared according to the method, and the application of the modified starch-based glass wool adhesive in the field of glass wool.

[0065] In this invention, the preparation method of the glass wool is a conventional method in the art, specifically including: heating and melting conventional glass wool raw materials, using a centrifugal blowing method to fiberize the molten glass wool raw materials to obtain glass fibers; blowing molten glass wool binder onto the surface of the glass fibers to obtain filamentous materials; collecting the filamentous materials and then heat-curing them, followed by cooling and cutting to obtain glass wool.

[0066] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0067] Unless otherwise specified, the test methods or experimental methods described in the following examples are all conventional methods; unless otherwise specified, the raw materials and additives are obtained from conventional commercial sources or prepared by conventional methods.

[0068] The preparation method of the auxiliary agent is as follows:

[0069] (1) Under the protection of an inert gas, myristic acid, ethylenediamine and cyclohexane are mixed, wherein the molar ratio of myristic acid and ethylenediamine is 2:1, and the amount of cyclohexane added is 3 times the mass of myristic acid (mL / g). The mixture is heated to 150°C and reacted for 2 hours. After the reaction is completed, the mixture is cooled to room temperature and discharged to obtain intermediate product a.

[0070] (2) Under the protection of an inert gas, N,N-dimethylthiourea and cyclohexane are added to intermediate product a, wherein the molar ratio of intermediate product a to N,N-dimethylthiourea is 1:3; the amount of cyclohexane added is 1 times the mass of myristic acid (mL / g), and the temperature is raised to 90°C and reacted for 4.5 h to intermediate product b;

[0071] (3) Under the protection of an inert gas, add cyclohexane to the intermediate product b, heat to 120°C, and slowly add isophorone diisocyanate to the system. The molar ratio of the intermediate product b to the isophorone diisocyanate is 1.5:1. The amount of cyclohexane added is 4.5 times (mL / g) of the mass of the intermediate product b. Keep the reaction at the temperature for 4 hours to obtain the intermediate product c.

[0072] (4) Under the protection of an inert gas, the intermediate product c, bromoacetic acid and methanol are mixed, the molar ratio of intermediate product c to bromoacetic acid is 1:3.5; the amount of methanol added is 7 times (mL / g) of the mass of intermediate product c, the temperature is raised to 40℃ and reacted for 1h, after the reaction is completed, the temperature is lowered to room temperature, and excess solvent is removed by vacuum evaporation to obtain the auxiliary agent.

[0073] Example 1

[0074] A method for preparing a modified starch-based glass wool adhesive, the specific steps of which are as follows:

[0075] (1) Take 10 kg of waxy corn starch, add 30 kg of 0.05 mol / L hydrochloric acid solution, stir and hydrolyze at 55℃ for 1.5 hours, neutralize with 1 mol / L NaOH to pH=6.8, filter, dry at 40℃ to obtain acid hydrolyzed starch;

[0076] (2) Take 8 kg of acid-hydrolyzed starch, add water to make a total weight of 20 kg (slurry concentration 40%), adjust pH to 8.5 with NaOH, heat to 45℃, slowly add sodium hypochlorite solution (effective chlorine content 240 g, i.e. 3% of starch mass), react for 2 hours, maintain pH=8.5 during the reaction, add 20 g of sodium bisulfite to reduce residual chlorine, filter, wash with water until no chloride ions are present, and obtain oxidized starch;

[0077] (3) The oxidized starch was redispersed in 15 kg of isopropanol, and 800 g of acetic anhydride (10% of the starch mass) and 40 g of DMAP (0.5%) were added. The reaction was carried out at 50 °C for 2 hours. After the reaction was completed, the pH was adjusted to 7.0 with dilute hydrochloric acid, filtered, washed 3 times with 70% ethanol, and dried at 40 °C to obtain oxidized-esterified composite modified starch.

[0078] (4) Weigh 1 kg of the modified starch, add 3 kg of water and stir to dissolve, add 120 g of sodium hypophosphite, add 50 g of additives, adjust the pH to 5.0 with citric acid, stir for 30 min, and obtain glass wool adhesive.

[0079] Example 2

[0080] A method for preparing a modified starch-based glass wool adhesive, the specific steps of which are as follows:

[0081] (1) Take 10 kg of waxy corn starch, add 30 kg of 0.05 mol / L hydrochloric acid solution, stir and hydrolyze at 55℃ for 1.5 hours, neutralize with 1 mol / L NaOH to pH=6.8, filter, dry at 40℃ to obtain acid hydrolyzed starch;

[0082] (2) Take 8 kg of acid-hydrolyzed starch, add water to a total weight of 20 kg (slurry concentration 40%), adjust pH to 8.5 with NaOH, heat to 45℃, slowly add sodium hypochlorite solution (effective chlorine content 240 g, i.e. 3% of starch mass) to carry out the reaction, maintain pH = 8.0~9.0 during the reaction, after 1.5 hours of reaction, directly add 800 g of acetic anhydride (10% of starch mass) and 40 g of DMAP (0.5%), continue the reaction at 50℃ for 2 hours, after the reaction is completed, adjust pH to 6.5 with dilute hydrochloric acid, filter, wash 3 times with 70% ethanol, dry at 40℃ to obtain oxidized-esterified composite modified starch;

[0083] (3) Weigh 1 kg of the modified starch, add 3 kg of water and stir to dissolve, add 120 g of sodium hypophosphite, add 50 g of additives, adjust the pH to 5.0 with citric acid, stir for 30 min, and obtain glass wool adhesive.

[0084] Comparative Example 1

[0085] Same as Example 1, except that the starch was not modified.

[0086] Comparative Example 2

[0087] Same as Example 1, except that the starch was not oxidized or esterified.

[0088] Comparative Example 3

[0089] Same as Example 1, except that the starch was not oxidized.

[0090] Comparative Example 4

[0091] Same as Example 1, except that the starch was not esterified.

[0092] Comparative Example 5

[0093] Same as Example 1, except that sodium hypophosphite was not added in step (4).

[0094] Comparative Example 6

[0095] Same as Example 1, except that in step (4), sodium tripolyphosphate is used to replace sodium hypophosphite.

[0096] Comparative Example 7

[0097] Same as Example 1, except that no additives were added in step (4).

[0098] Comparative Example 8

[0099] Same as Example 1, except that the mass ratio of modified starch, sodium hypophosphite, additives and water in step (4) is 100:12:1:300.

[0100] Comparative Example 9

[0101] Same as Example 1, except that: in step (4), the mass ratio of modified starch, sodium hypophosphite, additives and water is 100:12:9:300.

[0102] Test case

[0103] (i) The properties of the modified starches prepared in Examples 1-2 and Comparative Examples 1-4 were tested. The test results are shown in Table 1.

[0104] Table 1

[0105] Test Project Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Carboxyl content (mol%) 1.72 1.68 0.02 0.01 0.03 1.85 Degree of ester substitution (DS) 0.28 0.25 0 0 0.28 0 <![CDATA[Weight-average molecular weight (×10 4 )]]> 11.8 10.5 850 12.5 13.0 11.2

[0106] (ii) Test the foaming properties of the glass wool adhesives prepared in Examples 1-2 and Comparative Examples 1-9.

[0107] The foaming test method is as follows: weigh 5g of the adhesive prepared in each example or comparative example, dry it in a vacuum oven at 65℃, and then bake it at 180℃ for 3 minutes, and observe the foaming of the adhesive.

[0108] The test results are shown in Table 2.

[0109] Table 2

[0110] Test Project Adhesive foaming Example 1 There are a very small number of tiny bubbles, almost invisible to the naked eye. Example 2 There are a very small number of tiny bubbles, almost invisible to the naked eye. Comparative Example 1 The bubbles are dense, large in size, and unevenly distributed. Comparative Example 2 There are a large number of bubbles, some of which are quite large and unevenly distributed. Comparative Example 3 There are a large number of visible bubbles, evenly distributed. Comparative Example 4 There are a large number of visible bubbles, evenly distributed. Comparative Example 5 There are a large number of bubbles, some of which are quite large and unevenly distributed. Comparative Example 6 There are a few visible bubbles, evenly distributed. Comparative Example 7 The bubbles are dense, large in size, and unevenly distributed. Comparative Example 8 There are a few visible bubbles, evenly distributed. Comparative Example 9 There are a few visible bubbles, evenly distributed.

[0111] Table 2 shows that the glass wool adhesives prepared in Examples 1-2 of this invention have low foaming properties, meeting the performance requirements of glass wool. In Comparative Example 1, when natural starch was used directly as the glass wool adhesive, foaming was extremely severe, cross-linking was extremely slow, strength was extremely low, and water resistance was extremely poor, completely failing to meet the requirements for glass wool production. In Comparative Example 2, acid hydrolysis alone to reduce molecular weight was insufficient to solve the foaming problem of the glass wool adhesive during high-temperature curing. In Comparative Example 3, the absence of carboxyl groups led to increased foaming, proving that the introduction of carboxyl groups through oxidation is the key to solving the problem of easy foaming during high-temperature curing of the glass wool adhesive. In Comparative Example 4, the absence of esterification led to increased foaming. In Comparative Example 5, the absence of sodium hypophosphite led to severe foaming. In Comparative Example 6, foaming increased after replacing sodium hypophosphite with an equal amount of sodium trimetaphosphate. Comparative Example 7 shows that acid hydrolysis, oxidation, and esterification modification of starch alone cannot substantially solve the foaming problem; the addition of specific additives is the key to achieving ultra-low foaming. Comparative Examples 8 and 9 indicate that the amount of additives has a significant impact on product performance; only within a specific range can effective suppression of adhesive foaming be achieved.

[0112] (iii) The tensile strength and hydrophobicity of the glass wool prepared in Examples 1-2 and Comparative Examples 1-9, as well as the activation energy of the crosslinking reaction and the degree of crosslinking at 2 min, were tested. The test results are shown in Table 3.

[0113] The method for preparing the glass wool is a conventional method in the art, specifically as follows:

[0114] Conventional glass wool raw materials are heated and melted, and the molten glass wool raw materials are fiberized by centrifugal blowing to obtain glass fibers; molten glass wool binder is blown onto the surface of the glass fibers to obtain filamentous materials; the filamentous materials are collected and heat-cured at 190°C for 2 minutes, then cooled and cut to obtain glass wool.

[0115] Table 3

[0116] Test Project Tensile strength of glass wool (kPa) Water repellency of glass wool (%) Activation energy of cross-linking reaction (kJ / mol) Crosslinking degree (190℃, %) in 2 min Example 1 30.2 98.5 51.6 89.4 Example 2 31.5 98.2 50.2 91.2 Comparative Example 1 8.6 64.5 86.2 18.5 Comparative Example 2 18.2 85.4 68.5 42.3 Comparative Example 3 24.5 92.7 63.1 55.2 Comparative Example 4 20.1 78.3 59.3 78.7 Comparative Example 5 22.8 95.0 78.3 25.0 Comparative Example 6 25.4 90.6 65.4 52.1 Comparative Example 7 13.9 72.5 83.1 20.6 Comparative Example 8 27.3 88.9 62.7 56.3 Comparative Example 9 29.1 89.3 66.0 51.9

[0117] As shown in Table 3, the glass wool prepared in Examples 1-2 of the present invention can achieve a high-strength and highly water-resistant cross-linked network in a short time.

[0118] Comparative Example 1 has low tensile strength and water resistance, requires high energy for the reaction, is almost impossible to crosslink, and has an extremely low degree of crosslinking at 2 minutes, which is far from meeting the requirements of glass wool production lines and is difficult to use for glass wool production.

[0119] Comparative Example 2 showed poor tensile strength and water resistance. Acid hydrolysis alone could improve cold water solubility, but it could not solve the crosslinking problem.

[0120] Comparative Example 3 showed poor tensile strength and water resistance, with an activation energy (63.1 kJ / mol) significantly higher than that of the Example. The degree of crosslinking (55.2%) decreased drastically after 2 minutes, and the curing speed could not meet the requirements of the glass wool production line.

[0121] Comparative Example 4 has lower tensile strength and water resistance, and the reaction requires higher energy.

[0122] Comparative Example 5 had low tensile strength and water resistance, required high energy for the reaction, and showed a significant decrease in crosslinking degree (25.0%) after 2 minutes. The curing speed could not meet the requirements of the glass wool production line.

[0123] Comparative Example 6 had lower tensile strength and water resistance, and its activation energy (65.4 kJ / mol) was significantly higher than that of the Example. The degree of crosslinking (52.1%) decreased significantly after 2 minutes, and the curing speed could not meet the requirements of the glass wool production line.

[0124] The tensile strength and water resistance of the glass wool in Comparative Example 7 were significantly reduced. The reaction required higher energy, and the degree of crosslinking (20.6%) dropped sharply after 2 minutes. The curing speed could not meet the requirements of the glass wool production line. This may be because a large number of air bubbles were generated during curing, which severely damaged the integrity of the crosslinked network structure, resulting in poor strength and water resistance of the glass wool. At the same time, the large number of air bubbles hindered effective contact between molecules and slowed down the curing speed. In addition, compared with Example 1, Comparative Example 7, lacking additives, showed an increased activation energy and a decreased degree of crosslinking, indicating that the addition of additives is beneficial to improving the degree of crosslinking.

[0125] Comparative Examples 8 and 9 show that both higher and lower dosages of additives reduce the performance of glass wool, indicating that additives must be used within a specific dosage range to achieve their optimal effect.

[0126] Example 3

[0127] A method for preparing a modified starch-based glass wool adhesive, the specific steps of which are as follows:

[0128] (1) Take 10 kg of potato starch, add 30 kg of 0.05 mol / L hydrochloric acid solution, stir and hydrolyze at 40°C for 3 hours, neutralize with 1 mol / L NaOH to pH=6.5, filter, dry at 40°C to obtain acid hydrolyzed starch;

[0129] (2) Take 8 kg of acid-hydrolyzed starch, add water to a total weight of 20 kg (slurry concentration 40%), adjust pH to 8.5 with NaOH, heat to 35℃, slowly add sodium hypochlorite solution (effective chlorine content 240 g, i.e. 3% of starch mass), react for 3 hours, maintain pH=8.0 during the reaction, add 20 g of sodium bisulfite to reduce residual chlorine, filter, wash with water until no chloride ions are present, and obtain oxidized starch;

[0130] (3) The oxidized starch was redispersed in 15 kg of acetone, and 800 g of propionic anhydride (10% of the starch mass) and 40 g of pyridine (0.5%) were added. The reaction was carried out at 50 °C for 2 hours. After the reaction was completed, the pH was adjusted to 7.0 with dilute hydrochloric acid, filtered, washed 3 times with 70% ethanol, and dried at 40 °C to obtain oxidized-esterified composite modified starch.

[0131] (4) Weigh 1 kg of the modified starch, add 3 kg of water and stir to dissolve, add 120 g of sodium hypophosphite, add 50 g of additives, adjust the pH to 5.0 with citric acid, stir for 30 min, and obtain glass wool adhesive.

[0132] Example 4

[0133] A method for preparing a modified starch-based glass wool adhesive, the specific steps of which are as follows:

[0134] (1) Take 10 kg of sweet potato starch, add 30 kg of 0.05 mol / L hydrochloric acid solution, stir and hydrolyze at 50℃ for 0.8 hours, neutralize with 1 mol / L NaOH to pH=6.8, filter, dry at 40℃ to obtain acid hydrolyzed starch;

[0135] (2) Take 8 kg of acid-hydrolyzed starch, add water to a total weight of 20 kg (slurry concentration 40%), adjust pH to 8.5 with NaOH, heat to 40℃, slowly add sodium hypochlorite solution (effective chlorine content 240 g, i.e. 3% of starch mass), react for 1 hour, maintain pH=8.0 during the reaction, add 20 g of sodium bisulfite to reduce residual chlorine, filter, wash with water until no chloride ions are present, and obtain oxidized starch;

[0136] (3) The oxidized starch was redispersed in 15 kg of isopropanol, and 800 g of succinic anhydride (10% of the starch mass) and 40 g of pyridine (0.5%) were added. The reaction was carried out at 50 °C for 2 hours. After the reaction was completed, the pH was adjusted to 7.0 with dilute hydrochloric acid, filtered, washed 3 times with 70% ethanol, and dried at 40 °C to obtain oxidized-esterified composite modified starch.

[0137] (4) Weigh 1 kg of the modified starch, add 3 kg of water and stir to dissolve, add 120 g of sodium hypophosphite, add 50 g of additives, adjust the pH to 5.0 with citric acid, stir for 30 min, and obtain glass wool adhesive.

[0138] Example 5

[0139] A method for preparing a modified starch-based glass wool adhesive, the specific steps of which are as follows:

[0140] (1) Take 10 kg of potato starch, add 30 kg of 0.05 mol / L hydrochloric acid solution, stir and hydrolyze at 55℃ for 1.5 hours, neutralize with 1 mol / L NaOH to pH=6.5, filter, dry at 40℃ to obtain acid hydrolyzed starch;

[0141] (2) Take 8 kg of acid-hydrolyzed starch, add water to a total weight of 20 kg (slurry concentration 40%), adjust pH to 8.5 with NaOH, heat to 40℃, slowly add sodium hypochlorite solution (effective chlorine content 240 g, i.e. 3% of starch mass), react for 1 hour, maintain pH=8.0 during the reaction, add 20 g of sodium bisulfite to reduce residual chlorine, filter, wash with water until no chloride ions are present, and obtain oxidized starch;

[0142] (3) The oxidized starch was redispersed in 15 kg of acetone, and 800 g of octenyl succinic anhydride (10% of the starch mass) and 40 g of DMAP (0.5%) were added. The reaction was carried out at 50 °C for 2 hours. After the reaction was completed, the pH was adjusted to 7.0 with dilute hydrochloric acid, filtered, washed 3 times with 70% ethanol, and dried at 40 °C to obtain oxidized-esterified composite modified starch.

[0143] (4) Weigh 1 kg of the modified starch, add 3 kg of water and stir to dissolve, add 120 g of sodium hypophosphite, adjust the pH to 5.0 with citric acid, stir for 30 min, and obtain glass wool adhesive.

[0144] Example 6

[0145] A method for preparing a modified starch-based glass wool adhesive, the specific steps of which are as follows:

[0146] (1) Take 10 kg of potato starch, add 30 kg of 0.05 mol / L hydrochloric acid solution, stir and hydrolyze at 60°C for 2 hours, neutralize with 1 mol / L NaOH to pH=7.0, filter, dry at 40°C to obtain acid hydrolyzed starch;

[0147] (2) Take 8 kg of acid-hydrolyzed starch, add water to a total weight of 20 kg (slurry concentration 40%), adjust pH to 8.5 with NaOH, heat to 45℃, slowly add sodium hypochlorite solution (effective chlorine content 240 g, i.e. 3% of starch mass), react for 3 hours, maintain pH=9.0 during the reaction, add 20 g of sodium bisulfite to reduce residual chlorine, filter, wash with water until no chloride ions are present, and obtain oxidized starch;

[0148] (3) The oxidized starch was redispersed in 15 kg of acetone, and 800 g of octenyl succinic anhydride (10% of the starch mass) and 40 g of pyridine (0.5%) were added. The reaction was carried out at 50 °C for 2 hours. After the reaction was completed, the pH was adjusted to 7.0 with dilute hydrochloric acid, filtered, washed 3 times with 70% ethanol, and dried at 40 °C to obtain oxidized-esterified composite modified starch.

[0149] (4) Weigh 1 kg of the modified starch, add 3 kg of water and stir to dissolve, add 120 g of sodium hypophosphite, add 50 g of additives, adjust the pH to 5.0 with citric acid, stir for 30 min, and obtain glass wool adhesive.

[0150] Example 7

[0151] A method for preparing a modified starch-based glass wool adhesive, the specific steps of which are as follows:

[0152] (1) Take 10 kg of sweet potato starch, add 30 kg of 0.05 mol / L hydrochloric acid solution, stir and hydrolyze at 70°C for 3 hours, neutralize with 1 mol / L NaOH to pH=7.0, filter, dry at 40°C to obtain acid hydrolyzed starch;

[0153] (2) Take 8 kg of acid-hydrolyzed starch, add water to make a total weight of 20 kg (slurry concentration 40%), adjust pH to 8.5 with NaOH, heat to 50℃, slowly add sodium hypochlorite solution (effective chlorine content 240 g, i.e. 3% of starch mass), react for 3 hours, maintain pH=9.0 during the reaction, add 20 g of sodium bisulfite to reduce residual chlorine, filter, wash with water until no chloride ions are present, and obtain oxidized starch;

[0154] (3) The oxidized starch was redispersed in 15 kg of isopropanol, and 800 g of acetic anhydride (10% of the starch mass) and 40 g of pyridine (0.5%) were added. The reaction was carried out at 50 °C for 2 hours. After the reaction was completed, the pH was adjusted to 7.0 with dilute hydrochloric acid, filtered, washed 3 times with 70% ethanol, and dried at 40 °C to obtain oxidized-esterified composite modified starch.

[0155] (4) Weigh 1 kg of the modified starch, add 3 kg of water and stir to dissolve, add 120 g of sodium hypophosphite, add 50 g of additives, adjust the pH to 5.0 with citric acid, stir for 30 min, and obtain glass wool adhesive.

[0156] Testing revealed that the properties of the modified starch, glass wool binder, and glass wool prepared in Examples 3-7 were not significantly different from those in Example 1.

[0157] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a modified starch-based glass wool adhesive, characterized in that, Includes the following steps: (1) Mix natural starch and inorganic acid in a certain proportion to undergo hydrolysis reaction. After the reaction is completed, neutralize with alkali, filter and dry to obtain acid hydrolyzed starch; (2) Add water to the acid-hydrolyzed starch to prepare an acid-hydrolyzed starch slurry. Adjust the pH to 8.0~9.5 with alkali. Add an oxidant to carry out an oxidation reaction. After the reaction is completed, filter, wash and dry to obtain oxidized starch. (3) Dissolve the oxidized starch in the reaction medium, add esterifying agent and catalyst, carry out esterification reaction, neutralize with dilute hydrochloric acid after the reaction, filter, wash and dry to obtain pretreated modified starch; (4) The pretreated modified starch is mixed with sodium hypophosphite, additives and water in a certain proportion, the pH is adjusted to 4.0~6.0, and the mixture is stirred evenly to obtain glass wool adhesive.

2. The preparation method of the modified starch-based glass wool adhesive according to claim 1, characterized in that, The inorganic acid in step (1) is selected from any one of hydrochloric acid, sulfuric acid, and nitric acid; the natural starch is selected from any one of corn starch, potato starch, and sweet potato starch; the solid-liquid ratio of the natural starch and inorganic acid in step (1) is 1:2 to 1:4; the hydrolysis temperature in step (1) is 40 to 70°C, and the hydrolysis time is 0.5 to 3 hours; the drying process includes vacuum drying at 40°C until the moisture content is <10%.

3. The preparation method of the modified starch-based glass wool adhesive according to claim 1, characterized in that, The mass concentration of the acid-hydrolyzed starch slurry in step (2) is 30%~45%; the oxidant in step (2) is sodium hypochlorite; the process conditions for the oxidation reaction include: temperature 35~50℃, time 1~3 hours.

4. The preparation method of the modified starch-based glass wool adhesive according to claim 1, characterized in that, The esterifying agent in step (3) is selected from any one of acetic anhydride, propionic anhydride, succinic anhydride, and octenyl succinic anhydride; the amount of the esterifying agent is 5% to 20% of the dry starch mass; the process conditions for the esterification reaction in step (3) include: temperature 40 to 60°C, time 1 to 4 hours; the catalyst in step (3) is selected from any one of pyridine or 4-dimethylaminopyridine; the amount of the catalyst is 0.5% to 1% of the dry starch mass.

5. The preparation method of the modified starch-based glass wool adhesive according to claim 1, characterized in that, In step (4), the mass ratio of the pretreated modified starch, sodium hypophosphite, additives, and water is 100:(5~20):(3-8):(200~400).

6. The preparation method of the modified starch-based glass wool adhesive according to claim 1, characterized in that, The preparation method of the auxiliary agent is as follows: (1) Under the protection of inert gas, myristic acid, ethylenediamine and cyclohexane are mixed and heated to 110-170℃ for 1-3h. After the reaction is completed, the mixture is discharged at room temperature to obtain intermediate product a. (2) Under the protection of an inert gas, N,N-dimethylthiourea and cyclohexane are added to the intermediate product a, and the temperature is raised to 80-90℃ and reacted for 2-4.5h to obtain intermediate product b; (3) Under the protection of an inert gas, add cyclohexane to the intermediate product b, heat to 110-150℃, slowly add isophorone diisocyanate to the system, keep the reaction at the temperature for 4-5 hours, and then add intermediate product c. (4) Under the protection of an inert gas, the intermediate product c, bromoacetic acid and methanol are mixed and heated to 40-55℃ for 1-2 hours. After the reaction is completed, the mixture is cooled to room temperature and excess solvent is removed by vacuum evaporation to obtain the auxiliary agent.

7. The preparation method of the modified starch-based glass wool adhesive according to claim 6, characterized in that, In step (1), the molar ratio of myristic acid to ethylenediamine is 2:1; the amount of cyclohexane added is 2-5 times the mass of myristic acid; in step (2), the molar ratio of intermediate product a to N,N-dimethylthiourea is 1:3; the amount of cyclohexane added is 1-3 times the mass of myristic acid.

8. The preparation method of the modified starch-based glass wool adhesive according to claim 6, characterized in that, In step (3), the molar ratio of intermediate product b to isophorone diisocyanate is 1.5:1; the amount of cyclohexane added is 2-5 times the mass of intermediate product b; in step (4), the molar ratio of intermediate product c to bromoacetic acid is 1:3.5; the amount of methanol added is 5-8 times the mass of intermediate product c.

9. The modified starch-based glass wool adhesive prepared by the method according to any one of claims 1-8.

10. The modified starch-based glass wool adhesive prepared by the method according to any one of claims 1-8, or the application of the modified starch-based glass wool adhesive according to claim 9 in the field of glass wool.