Preparation method of high-performance hydroxypropyl starch ether and high polymer material composite product

Abstract

The invention belongs to the technical field of starch ether composite materials, and relates to a preparation method of a high-performance hydroxypropyl starch ether and high-molecular material composite product, which comprises the following steps: dissolving a high-molecular material in ethanol, adding an etherifying agent as a reaction dispersant, successively adding starch, an alkalizing agent and an inhibitor, mixing, alkalizing for a certain time, heating for modification, and cooling to obtain the high-performance hydroxypropyl starch ether and high-molecular material composite product. The high-performance hydroxypropyl starch ether and high polymer material composite product is obtained; according to the invention, a high polymer material and alcohol are mixed as a reaction dispersant, and the reaction efficiency of the etherifying agent is improved on the basis of retaining the performance of the existing product by changing the preparation solvent of starch ether; the product has excellent lubricant, plasticity and thickening property, and can be used for preparing putty powder or mortar, and the viscosity, consistency and water retention rate of the putty powder or mortar are remarkably improved; the advantages of hydroxypropyl starch ether and a high polymer material are completely fused, and a better choice is provided for terminal customers. The preparation method is simple in process, easy to operate, suitable for large-scale popularization and application and wide in market prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of starch ether composite materials and relates to a method for preparing a high-performance hydroxypropyl starch ether and polymer material composite product. Background Art

[0002] Chemical modification of starch refers to treating the original starch with chemical reagents to change its structure and properties to meet the application requirements. Generally speaking, chemically modified starch can be divided into two categories. One is that the molecular weight of the modified starch is reduced, such as acid-hydrolyzed starch, oxidized starch, etc. The other is that the molecular weight of the modified starch is increased, such as cross-linked starch, esterified starch, carboxymethyl starch and hydroxypropyl starch.

[0003] There are two main types of chemical modifications that are most widely used in the market. One is hydroxypropyl (carboxymethyl) starch, which is an ether compound generated by the substitution reaction of propylene oxide (sodium chloroacetate) with the hydroxyl group in starch under alkaline conditions to introduce hydroxypropyl (carboxymethyl) groups into starch. A multi-group cross-linked modified starch ether generated by adding a cross-linking agent to hydroxypropyl starch as a basis. As described in patent No. 202110461697.2, a preparation of a cross-linked carboxymethyl hydroxypropyl composite modified starch. The cross-linked carboxymethyl hydroxypropyl composite modified starch ether retains the hydrophilic characteristics brought by hydroxypropylation, improves construction performance and water retention, and at the same time, due to the introduction of carboxyl groups, greatly increases the consistency, which brings a substantial improvement in anti-sagging properties.

[0004] Sodium polyacrylate is a polymer compound that is commonly used to make various water-based adhesives, controlled release agents, polymer dispersants, etc. It is widely used in many fields such as construction, chemicals, plastics, medicine, and textiles. The role of sodium polyacrylate mortar is mainly reflected in the following aspects: 1. Improving the toughness and adhesion of mortar: Compared with traditional mortar, sodium polyacrylate mortar has higher strength, stronger hardness, and better toughness. At the same time, it can also increase the adhesion of mortar, making the mortar more tightly bonded to building materials, thereby improving the overall stability of the building. 2. Increase the water resistance and durability of mortar: Sodium polyacrylate mortar is not only moisture-proof and waterproof, but also maintains a certain flexibility and is not easy to crack or crack. Therefore, it can not only maintain good performance in a humid environment, but also maintain its performance well under complex conditions such as climate change and temperature change.

[0005] However, with the continuous development of the market, hydroxypropyl starch ether and composite starch ether products can no longer meet the requirements of the terminal market. While pursuing the lubricity and thickening brought by the thixotropic characteristics of starch ether, hydroxypropyl starch ether and composite modified starch ether also bring the risk of strength loss in cement-based products and gypsum-based products. Therefore, many companies choose to add polymer materials to give the system lubricity, but lack the thixotropy that starch ether should have. It is necessary to develop a method that combines polymer materials and starch ethers into one, solve the disadvantages of the existing single components, and give play to the complementary advantages of the two. Summary of the invention

[0006] The purpose of the present invention is to solve the defects of the prior art and provide a method for preparing a high-performance hydroxypropyl starch ether and polymer material composite product. On the basis of retaining the performance of the existing product, the preparation solvent of the starch ether is changed to improve the reaction efficiency of the etherifying agent, so that the starch ether particles are attached around the polymer crystals to obtain a new type of composite material.

[0007] In order to achieve the above object, the present invention provides a method for preparing a high-performance hydroxypropyl starch ether and polymer material composite product, which is carried out according to the following steps: (1) Solution preparation: polymer material, etherifying agent and alcohol are mixed to prepare a dispersible solution as a reactive dispersant; (2) Alkalization: After adding starch, alkalizer and inhibitor to the reaction dispersant, alkalize for a certain period of time to obtain an alkalized product; (3) Preparation of crude product: The alkalized material is heated to carry out etherification reaction. After the reaction is completed, the solvent in the reaction system is placed in a condenser by heating to be condensed and recovered. The material recovered by the solvent is the crude product; (4) Preparation of a new composite product: The crude product is crushed to obtain a high-performance composite product of hydroxypropyl starch ether and polymer material.

[0008] The polymer material of the present invention is one or more of polyvinyl alcohol, polyethylene oxide, polyacrylamide and sodium polyacrylate; the starch is one or more of potato starch, cassava starch and corn starch; the alkalizer is an alkali metal hydroxide; the alcohol is one or more of methanol, ethanol, isopropanol, n-butanol, tert-butanol, acetone and diethylene glycol; the inhibitor is an alkali metal salt; the etherifying agent is one or more of chloroacetic acid, methyl chloride, ethyl chloride, propylene glycol ether, propylene oxide and ethylene oxide.

[0009] The polymer material of the present invention is sodium polyacrylate; the alkali metal hydroxide is sodium hydroxide; the alcohol is ethanol; the inhibitor is one or both of sodium sulfate and sodium chloride; and the etherifying agent is propylene oxide.

[0010] The alkalization reaction time of the present invention is 30-50 minutes, and the alkalization temperature is 20-30°C; the etherification reaction is: heating to 50-60°C, maintaining for 1.5-2 hours, and then heating to 70-50°C, maintaining for 1-1.5 hours.

[0011] The mass ratio of the starch, polymer material, alkalizer, inhibitor, alcohol and etherifying agent described in the present invention is 1: (0.01-0.1): (0.05-0.2): (0.05-0.1): (0.1-1): (0.1-1).

[0012] The present invention also provides application of the high-performance hydroxypropyl starch ether and polymer material composite product prepared by the preparation method in preparing putty powder or mortar.

[0013] Compared with the prior art, the present invention mixes polymer materials with alcohol as a reaction dispersant, and by changing the preparation solvent of starch ether, the reaction efficiency of the etherifying agent is improved on the basis of retaining the performance of the existing product, and the starch ether particles are attached around the polymer crystals to obtain a new type of composite material. After desolventizing, the reaction product of the present invention can be directly crushed without drying. The product has excellent lubricity, plasticity, and thickening, and can be used to prepare putty powder or mortar, significantly improving its viscosity, consistency and water retention rate; while ensuring that the use cost is not superimposed, the product fully integrates the advantages of hydroxypropyl starch ether and polymer materials, providing a better choice for terminal customers. The preparation method is simple in process, easy to operate, suitable for large-scale promotion and application, and has broad market prospects. DETAILED DESCRIPTION

[0014] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments.

[0015] Embodiment 1: This embodiment relates to a method for preparing a high-performance hydroxypropyl starch ether and polymer material composite product, and the specific steps are: (1) Solution preparation: 50 parts by weight of ethanol, 20 parts by weight of etherifying agent propylene oxide and 2 parts by weight of sodium polyacrylate were added into a reaction kettle and stirred and dispersed for 0.5 h to serve as a reaction dispersant; (2) Alkalization: Add 100 parts of starch, 10 parts of sodium hydroxide and 10 parts of inhibitor sodium sulfate into a reactor by weight, and alkalize at 25°C for 40 minutes; (3) Preparation of crude product: first carry out etherification reaction, then recover the solvent, specifically: Etherification: raise the temperature to 50°C and keep it for 1.5 hours, then raise the temperature to 70°C and keep it for 1.5 hours; Recovery: Turn on the hot water pump, slowly raise the temperature from 70°C to 110°C, wait until the pressure in the kettle drops to 0.2 MPa, turn on the vacuum pump, and recover the solvent through the condenser; (4) Crushing and packaging: The dried material is sent to a micro-powder machine for crushing to an 80-mesh screening rate of more than 99%. After passing the inspection, it is packaged and stored to obtain a starch ether-based polymer material composite product, that is, a high-performance hydroxypropyl starch ether and polymer material composite product.

[0016] Embodiment 2: This embodiment relates to a method for preparing a high-performance hydroxypropyl starch ether and polymer material composite product, and the specific steps are: (1) Solution preparation: 40 parts by weight of ethanol, 30 parts by weight of etherifying agent propylene oxide and 6 parts by weight of sodium polyacrylate were added into a reaction kettle and stirred and dispersed for 0.6 hours to serve as a reaction dispersant; (2) Alkalization: Add 100 parts of starch, 8 parts of sodium hydroxide, and 10 parts of inhibitor sodium chloride into a reactor by weight, and alkalize at 25°C for 30 minutes; (3) Preparation of crude product: first carry out etherification reaction, then recover the solvent, specifically: Etherification: raise the temperature to 55°C, maintain for 1.5 hours, raise the temperature to 75°C, maintain for 1.5 hours; Recovery: Turn on the hot water pump, slowly raise the temperature from 75°C to 120°C, wait until the pressure in the kettle drops to 0.2 MPa, turn on the vacuum pump, and recover the solvent through the condenser; (4) Crushing and packaging: The dried material is sent to a micro-powder machine for crushing to an 80-mesh screening rate of more than 99%. After passing the inspection, it is packaged and stored to obtain a starch ether-based polymer material composite product, that is, a high-performance hydroxypropyl starch ether and polymer material composite product.

[0017] Embodiment 3: This embodiment relates to a method for preparing a high-performance hydroxypropyl starch ether and polymer material composite product, and the specific steps are: (1) Solution preparation: 30 parts by weight of ethanol, 30 parts by weight of etherifying agent propylene oxide and 4 parts by weight of sodium polyacrylate were added into a reaction kettle and stirred and dispersed for 0.5 h to serve as a reaction dispersant; (2) Alkalization: Add 100 parts of starch, 12 parts of sodium hydroxide and 10 parts of inhibitor sodium sulfate into a reactor by weight, and alkalize at 25°C for 50 minutes; (3) Preparation of crude product: first carry out etherification reaction, then recover the solvent, specifically: Etherification: raise the temperature to 60°C, maintain for 2 hours, raise the temperature to 80°C, maintain for 1 hour; Recovery: Turn on the hot water pump, slowly raise the temperature from 80°C to 120°C, wait until the pressure in the kettle drops to 0.2 MPa, turn on the vacuum pump, and recover the solvent through the condenser; (4) Crushing and packaging: The dried material is sent to a micro-powder machine for crushing to an 80-mesh screening rate of more than 99%. After passing the inspection, it is packaged and stored to obtain a starch ether-based polymer material composite product, that is, a high-performance hydroxypropyl starch ether and polymer material composite product.

[0018] Embodiment 4: This embodiment relates to a method for preparing a high-performance hydroxypropyl starch ether and polymer material composite product, and the specific steps are: (1) Solution preparation: Add 20 parts by weight of ethanol, 30 parts by weight of etherifying agent propylene oxide and 5 parts by weight of sodium polyacrylate into a reaction kettle and stir and disperse them to serve as a reaction dispersant; (2) Alkalization: Add 100 parts of starch, 10 parts of sodium hydroxide and 10 parts of inhibitor sodium sulfate into a reactor by weight, and alkalize at 25°C for 40 minutes; (3) Preparation of crude product: first carry out etherification reaction, then recover the solvent, specifically: Etherification: raise the temperature to 55°C, maintain for 1.5 hours, raise the temperature to 75°C, maintain for 1.5 hours; Recovery: Turn on the hot water pump, slowly raise the temperature from 75°C to 120°C, wait until the pressure in the kettle drops to 0.2 MPa, turn on the vacuum pump, and recover the solvent through the condenser; (4) Crushing and packaging: The dried material is sent to a micro-powder machine for crushing to an 80-mesh screening rate of more than 99%. After passing the inspection, it is packaged and stored to obtain a starch ether-based polymer material composite product, that is, a high-performance hydroxypropyl starch ether and polymer material composite product.

[0019] Embodiment 5: This embodiment relates to the application effect of the starch ether-based polymer material composite product prepared in Examples 1-5, and takes commercially available hydroxypropyl starch ether as a comparative example. The moisture content, viscosity and hydroxypropyl content of the product prepared in Example 3 and the comparative example are tested according to the test methods commonly used in the art. The results are shown in Table 1.

[0020] Table 1 Physical and chemical indicators

[0021] From the comparison of physical and chemical indicators in Table 1, it can be seen that compared with the comparative example, the hydroxypropyl content and water content of Example 3 did not change much, but the viscosity was significantly improved. This is because the polymer material dispersed in ethanol was used as the solvent medium, and the hydroxypropyl starch ether particles were attached to the polymer material crystals after heating and drying, which greatly increased the viscosity, and the hydroxypropyl content in the starch ether was not affected.

[0022] The product prepared in Example 3 was used as a mortar raw material to detect its effect on the mortar performance. Specifically, by weight, 0.3 parts of the product prepared in Example 3, 300 parts of ordinary Portland cement, 700 parts of standard sand, 2 parts of HPMC (hydroxypropyl methylcellulose) and an appropriate amount of water were used as raw materials. The mortar was prepared according to the existing mortar preparation method, and the consistency of the mortar was detected according to the standard JGJ_T70-09 Test method for basic properties of building mortar; the product prepared in Example 3 was replaced by commercially available hydroxypropyl starch ether, and mortar was prepared according to the above method as a comparative example; the consistency test results are shown in Table 2.

[0023] Table 2 Consistency test results

[0024] The water retention rate of the mortar prepared in Examples 1-4 was tested according to JGJ_T70-09 standard test method for basic properties of building mortar, and the mortar prepared with commercially available hydroxypropyl starch ether was used as a comparative example. The results are shown in Table 3.

[0025] Table 3 Test results of mortar water retention

[0026] It can be seen from Table 3 that the water retention rate of the mortar prepared using the product of Example 3 is the highest.

[0027] From the above data, it can be seen that the starch ether-based polymer material composite product prepared by the preparation method of the high-performance hydroxypropyl starch ether and polymer material composite product of the present invention can be used for the preparation of mortar, and is significantly superior to single hydroxypropyl starch ether in viscosity, water retention and thickening.

[0028] According to the standard JC / T298-2010 "Putty Powder for Building Interior Use", an asbestos-free fiber cement slab was selected, and combined with the second method of GB / T1728-1979, 40% water was added and stirred evenly. The slipperiness and wettability were determined according to the surface dryness and construction requirements. The components of the comparative putty powder and the putty powder prepared using the products of Examples 1-4 are shown in Table 4.

[0029] Table 4 Putty powder components

[0030] Putty powder prepared by the comparative example and the products of Examples 1-4 was used for putty powder coating operation, and the effects are shown in Table 5.

[0031] Table 5 Putty powder coating effect

[0032] It can be seen from Table 5 that through the coating experiment of putty powder, the putty powder of Experimental Example 3 prepared from the hydroxypropyl starch ether prepared in Example 3 and the polymer material composite product has improved workability and wettability compared with commercially available hydroxypropyl starch ether.

Claims

1. A method for preparing a high-performance hydroxypropyl starch ether and polymer material composite product, characterized in that: Follow these steps: (1) Solution preparation: polymer material, etherifying agent and alcohol are mixed to prepare a dispersible solution as a reactive dispersant; (2) Alkalization: After adding starch, alkalizer and inhibitor to the reaction dispersant, alkalize for a certain period of time to obtain an alkalized product; (3) Preparation of crude product: The alkalized material is heated to carry out etherification reaction. After the reaction is completed, the solvent in the reaction system is placed in a condenser by heating to be condensed and recovered. The material recovered by the solvent is the crude product; (4) Preparation of new composite products: The crude product is crushed to obtain a high-performance hydroxypropyl starch ether and polymer material composite product.

2. The method for preparing the high-performance hydroxypropyl starch ether and polymer material composite product according to claim 1, characterized in that: The polymer material is one or more of polyvinyl alcohol, polyethylene oxide, polyacrylamide, and sodium polyacrylate; the starch is one or more of potato starch, cassava starch, and corn starch; the alkalizer is an alkali metal hydroxide; the alcohol is one or more of methanol, ethanol, isopropanol, n-butanol, tert-butanol, acetone, and diethylene glycol; the inhibitor is an alkali metal salt; and the etherifying agent is one or more of chloroacetic acid, methyl chloride, ethyl chloride, propylene glycol ether, propylene oxide, and ethylene oxide.

3. The method for preparing the high-performance hydroxypropyl starch ether and polymer material composite product according to claim 1, characterized in that: The polymer material is sodium polyacrylate; the alkali metal hydroxide is sodium hydroxide; the alcohol is ethanol; the inhibitor is one or both of sodium sulfate and sodium chloride; and the etherifying agent is propylene oxide.

4. The method for preparing the high-performance hydroxypropyl starch ether and polymer material composite product according to claim 1, characterized in that: The alkalization reaction time is 30-50 minutes, and the alkalization temperature is 20-30° C.; the etherification reaction is: heating to 50-60° C., maintaining for 1.5-2 hours, and then heating to 70-50° C., maintaining for 1-1.5 hours.

5. The method for preparing the high-performance hydroxypropyl starch ether and polymer material composite product according to claim 1, characterized in that: The mass ratio of the starch, polymer material, alkalizer, inhibitor, alcohol and etherifying agent is 1: (0.01-0.1): (0.05-0.2): (0.05-0.1): (0.1-1): (0.1-1).

6. Use of the high-performance hydroxypropyl starch ether and polymer material composite product prepared by the preparation method according to any one of claims 1 to 5 in the preparation of putty powder or mortar.

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