Preparation method of modified binder

Abstract

The invention provides a preparation method of a modified binder, which comprises the following steps: firstly, synthesizing dimethyl silicon polyvinyl ester by taking polyvinyl alcohol and dimethyl dichlorosilane as raw materials, and then adding the synthesized dimethyl silicon polyvinyl ester into an organic binder for compounding to obtain the modified binder. The modified binder has higher heat resistance, flame retardance and waterproofness, can be applied to scenes with higher performance requirements on the binder, especially some scenes in which a welding technology cannot be used, such as underwater repair, an oil bin of a transport ship, a natural gas bin and the like, and the repair cost is reduced; the method can be used for a pipeline system and simplifies the repair process. The preparation method of the modified binder is green, environment-friendly and low in cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of adhesives, in particular to a preparation method of modified adhesives. BACKGROUND

[0002] Vinyl acetate-ethylene copolymer emulsion (VAE emulsion for short) is one of the main raw materials of adhesives. VAE emulsion can be classified according to polymerization process, modification type and solid content. According to the polymerization process, it is divided into continuous polymerization emulsion and batch polymerization emulsion, which are suitable for large-scale factory production and small-scale factory production or special formula development, respectively. According to the modification type, it is divided into unmodified emulsion and modified emulsion, and the modified emulsion improves specific performance by adding functional monomers or additives. According to the solid content, it is divided into high solid content emulsion and low solid content emulsion, and the high solid content is suitable for post-coating and high viscosity application, and the low solid content is suitable for general purpose and low viscosity application.

[0003] At present, the materials used for compounding with VAE emulsion to modify adhesives mainly include butyl acrylate, acrylic acid, starch, carboxyl styrene butadiene latex, etc. For example, the addition of butyl acrylate can improve the flexibility and low temperature resistance of the adhesive, and the addition of acrylic acid can improve the stability of the adhesive and increase the bonding strength. For application scenarios with high requirements for heat resistance, flame retardance and waterproofness of adhesives, especially some application scenarios that cannot use welding technology, such as underwater repair, oil tank repair of transport ships, natural gas tank repair, etc., the existing adhesives cannot fully meet the application requirements of such scenarios.

[0004] China is the main producer and exporter of VAE emulsion, and in recent years the domestic demand and export scale have grown steadily. Research and development of new modified materials for compounding with VAE emulsion have positive significance for improving market competitiveness and increasing the production capacity of adhesives. SUMMARY

[0005] The purpose of the present application is to provide a preparation method of modified adhesives, which can significantly improve the heat resistance, flame retardance and waterproofness of organic adhesives.

[0006] To achieve the above purpose, the present application provides a preparation method of modified adhesives, comprising the following steps: S1, using polyvinyl alcohol and dimethyldichlorosilane as raw materials to synthesize a compound with formula (I) structure: (I) wherein n is a positive integer; S2, adding the synthesized compound with formula (I) structure into an organic adhesive to obtain a modified adhesive.

[0007] As a further improvement of the present application, the polyvinyl alcohol is a polyvinyl alcohol solution, and the polyvinyl alcohol solid is dissolved in an organic solvent to obtain the polyvinyl alcohol solution.

[0008] As a further improvement of the present application, the organic solvent comprises dioxane and dimethyl sulfoxide.

[0009] As a further improvement of the present application, in step S1, the dimethyldichlorosilane is gradually added to the heated polyvinyl alcohol solution, and the synthesis is carried out in a preset temperature range to obtain the compound of formula (I).

[0010] As a further improvement of the present application, in step S1, the polyvinyl alcohol solution is heated During the heating process, the dimethyldichlorosilane solution is added dropwise until the reaction temperature reaches a preset temperature, and then the addition of the dimethyldichlorosilane solution is stopped; The reaction is kept at the preset temperature for a period of time, and then the reaction is stopped when the reaction product is in a gel state, to obtain the compound of formula (I), wherein the preset temperature is not higher than 70℃.

[0011] As a further improvement of the present application, step S1 further comprises: after stopping the reaction, cooling the reaction product to room temperature, and washing the reaction product with water to obtain the compound of formula (I).

[0012] As a further improvement of the present application, n is an integer selected from 1000-3000.

[0013] As a further improvement of the present application, in step S2, the synthesized compound of formula (I) is compounded with a vinyl acetate-ethylene copolymer emulsion at a preset ratio.

[0014] As a further improvement of the present application, polyvinyl acetate is further added to the modified adhesive as a dispersant.

[0015] Compared with the prior art, the present application has the following advantages: The preparation method of the modified adhesive provided by the present application synthesizes a new modified compound, dimethyl silicon polyvinyl ester (DSPE), to modify the organic adhesive, so that the prepared modified adhesive has high heat resistance, flame retardance and waterproofness, and can be applied to some special scenes, especially scenes where welding technology cannot be used, such as underwater repair, oil tanks of transport ships, natural gas tanks, etc., to improve work efficiency and reduce repair cost; and can also be used for repairing pipeline systems, simplifying the repair process.

[0016] By adding dimethylsilicon polyethylene ester (DSPE) as a modified material for the organic binder, for the same amount of the organic binder, the proportion of the basic raw materials of the original organic binder can be reduced, thereby reducing the cost of the basic raw materials of the organic binder; from another perspective, for the same amount of the basic raw materials of the organic binder, more modified binders with better performance can be prepared. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic flow chart of a method for preparing a modified binder provided by the present application.

[0018] Figure 2 It is an infrared spectrum analysis chart of dimethylsilicon polyethylene ester synthesized by an embodiment provided by the present application.

[0019] Figure 3 It is a thermal difference analysis spectrum chart of dimethylsilicon polyethylene ester synthesized by an embodiment provided by the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] The present invention will be described in detail below in conjunction with the embodiments shown in the drawings. However, it should be noted that these embodiments are not limitations on the present invention, and any equivalent transformation or substitution in terms of function, method, or structure made by those of ordinary skill in the art based on these embodiments shall fall within the protection scope of the present invention.

[0021] Refer Figure 1 As shown, the present application provides a method for preparing a modified binder, including the following steps: S1. Synthesis of the modified compound: Using polyvinyl alcohol and dimethyldichlorosilane as raw materials, a compound with the structure of formula (I) is synthesized: [[ID=二十九]](I) Where n is a positive integer; Step S2. Blending: Adding the synthesized compound with the structure of formula (I) to the organic binder to obtain a modified binder.

[0022] According to the structure of formula (I), the applicant names this compound dimethylsilicon polyethylene ester, abbreviated as DSPE in English.

[0023] Synthesis method of the modified compound The present application provides a reaction principle equation for synthesizing a compound with the structure of formula (I): Polyvinyl alcohol (PVA) and dimethyldichlorosilane (DMDCS) are reacted under certain conditions to produce dimethylsilicon polyethylene ester (DSPE).

[0024] In one implementation, n is an integer selected from 1000 to 3000.

[0025] In one embodiment, a synthetic formula (I) based on the above-described reaction principle equation is provided. The method involves compounds. The raw materials used include polyvinyl alcohol (PVA) (solid), dimethyldichlorosilane (DMDCS) (liquid), dioxane (liquid), and dimethyl sulfoxide (liquid).

[0026] The specific steps are as follows: First, a polyvinyl alcohol (PVA) solution is prepared: equal volumes of dioxane and dimethyl sulfoxide are mixed, and then a small amount of PVA is added and stirred to dissolve, thus obtaining a PVA solution. For example, in one embodiment, 50 ml of dioxane and 50 ml of dimethyl sulfoxide are first added to a container and mixed thoroughly, and then 5 g of PVA is added and stirred to dissolve, thus preparing a PVA solution.

[0027] Then, the synthesis reaction is carried out: the polyvinyl alcohol solution is allowed to stand in a desiccator for 1-2 days. A certain amount of polyvinyl alcohol solution is poured into a four-necked flask equipped with a stirrer, thermometer, reflux condenser and HCl absorption device. While heating, dimethyldichlorosilane (DMDCS) solution is added dropwise until the temperature reaches 70°C and then the addition is stopped. The reaction is refluxed at a constant temperature for 4-6 hours. When the amount of liquid recovered by condensation reaches the theoretical calculation value, the reaction is stopped when the state of the substance in the flask is gelatinous. After cooling to room temperature, the product is transferred to a separatory funnel and washed with 2-3 times the theoretical mass of the product in milliliters of water until the pH reaches 6-7. This yields a reaction product that is slightly flocculent and pale yellow.

[0028] In one embodiment, the reaction product is a compound with the structure of formula (I): (I) The average value of n is 1500.

[0029] The synthesis effect of the modified compound was verified: Specifically, the obtained reaction products were subjected to infrared spectroscopy analysis, and the infrared spectral characterization of the products was as follows: Figure 1 As shown. 3410 cm -1 The peak at 1180 cm⁻¹ is the absorption peak of the stretching vibration of -OH in polyvinyl alcohol (PVA), while the -OH absorption peak at that position has disappeared in the product dimethyl silicone polyethylene ester (DSPE); at the same time, the infrared spectrum of dimethyl silicone polyethylene ester (DSPE) at 1180 cm⁻¹... -1 A stronger peak was observed at 2890 cm⁻¹, which is the stretching vibration absorption peak of the -Si-OC- functional group, proving that the -OH group in polyvinyl alcohol (PVA) has fully reacted with dimethyldichlorosilane.-1 With 2980 cm -1 The peaks at 2980 cm⁻¹ represent the stretching and bending vibrations of -CH₂- in polyvinyl alcohol (PVA), respectively. Due to the formation of the -Si-OC- functional group, the bending vibration of -CH₂- in PVA is inhibited. -1 The peak at 946 cm⁻¹ was significantly weakened. However, in the infrared spectrum of polyvinyl alcohol (PVA), the peak at 946 cm⁻¹ was significantly reduced. -1 1090cm -1 There are strong absorption peaks at the two locations, which are generated by the carbon chain and -CO- stretching vibrations, respectively. However, in the infrared spectrum of the product dimethyl silicone polyethylene ester (DSPE), both peaks are significantly weakened. This is because the formation of the -Si-OC- bond hinders the carbon chain swing and -CO- stretching in polyvinyl alcohol (PVA), proving the successful synthesis of the product dimethyl silicone polyethylene ester (DSPE).

[0030] Thermal stability test Thermogravimetric (TG)-differential thermal (DTA) analysis was performed on the obtained reaction product, dimethylsiloxane polyethylene ester (DSPE). The results are as follows: Figure 3 As shown in the figure. The experiment found that the TG curve showed significant weight loss at 480℃, while the DTA curve showed a strong exothermic peak at 480℃, indicating that the reaction product has good thermal stability and the thermal decomposition temperature reaches 480℃.

[0031] Preparation of modified adhesives The reaction product, dimethyl silicone polyethylene ester (DSPE), is compounded with the base raw materials of the adhesive to improve the heat resistance, flame retardancy, and water resistance of the adhesive.

[0032] In one embodiment, the reaction product dimethyl silicone polyethylene ester (DSPE) is compounded with vinyl acetate-ethylene copolymer emulsion (i.e., VAE emulsion) to improve the heat resistance, flame retardancy, and water resistance of the VAE emulsion. Specifically, dimethyl silicone polyethylene ester (DSPE) is added to the VAE emulsion in an appropriate proportion, and an appropriate amount of dispersant polyvinyl acetate is added and rapidly stirred until uniformly mixed to obtain a modified binder based on VAE emulsion (hereinafter referred to as modified binder).

[0033] The viscosity (η) of the modified adhesive under gravity was tested using a mechanical Ubbelohde viscometer, and the calculated viscosity reached 4500 cp. Furthermore, the modified adhesive exhibits moderate surface tension and good adhesion to surfaces such as ordinary stainless steel, textiles, and wood.

[0034] Application testing of modified adhesives The modified adhesive is applied between two pieces of fabric and between two pieces of stainless steel, and then pressed firmly for bonding. At room temperature of around 5°C, the emulsion needs 5 hours to dry completely; at room temperature of around 15°C, the emulsion needs 3 hours to dry completely; and at room temperature of around 25°C, the emulsion needs 1 hour to dry completely.

[0035] Water resistance test of modified adhesive A suitable amount of modified adhesive was dropped into a beaker, and an equal volume of water was added and stirred to obtain a cloudy, opaque mixture. After standing for 30 minutes, a layer of gelatinous substance precipitated at the bottom of the beaker. Simultaneously, two stainless steel sheets used in the application test of the modified adhesive were immersed in water for 2 hours. The two stainless steel sheets remained firmly bonded, without the adhesive becoming wet or peeling off. This indicates that the modified adhesive has excellent waterproof performance.

[0036] Heat resistance test of modified adhesive Dimethyl silicone polyethylene ester (DSPE) was added to VAE emulsions in different compounding ratios to obtain several modified adhesives. For example, DSPE was added to VAE emulsions at addition amounts of 0%, 5%, 10%, 15%, and 20%, respectively, to prepare modified adhesive 1, modified adhesive 2, modified adhesive 3, modified adhesive 4, and modified adhesive 5.

[0037] Modified adhesive 1, modified adhesive 2, modified adhesive 3, modified adhesive 4, and modified adhesive 5 were respectively applied to the surface of the wood board, for example, with a coating thickness of 1-2 mm. The corresponding wood board surfaces were then burned with an alcohol torch. The temperature resistance range of modified adhesive 1-5 and the discoloration of the sample surface were observed. The analysis is shown in Table 1 below.

[0038] Table 1 Heat Resistance Analysis Table Analysis of the test phenomena in Table 1 shows that dimethyl silicone polyethylene ester (DSPE) can significantly improve the heat resistance of VAE emulsion, thereby improving the adhesive with better heat resistance.

[0039] Experiments have shown that the compounding ratio of dimethyl silicone polyethylene ester (DSPE) should not exceed 50%. That is, for a VAE emulsion, the addition amount of dimethyl silicone polyethylene ester (DSPE) should be within the range of 50% to obtain a better modification effect.

[0040] Flame retardancy and anti-dripping properties The applicant, by further increasing the compounding ratio of dimethyl silicone polyethylene ester (DSPE) in the VAE emulsion, obtained a modified adhesive with a maximum heat resistance temperature of 830℃. At 650℃, the modified adhesive exhibited agglomeration, with the edges of the bulging cages turning yellow. As the temperature increased, the edges of the cages gradually turned black, and the height and surface area of ​​the bulges gradually decreased. This demonstrates that the modified adhesive possesses good flame retardancy and anti-dripping properties at high temperatures.

[0041] Application scenarios of modified adhesives The synthesis method provided in the above embodiments synthesizes a novel modified compound—dimethylsilicone polyethylene ester (DSPE)—to modify organic adhesives, resulting in modified adhesives with high heat resistance, flame retardancy, and water resistance. This allows for applications requiring high heat resistance, flame retardancy, and water resistance, particularly in situations where welding techniques are not feasible, such as underwater repairs, oil tanks on transport ships, and natural gas tanks. It can also be used for pipeline system repair, simplifying the repair process.

[0042] In other alternative embodiments, the modified compound—dimethylsilicone polyethylene ester (DSPE)—can also be used in other organic binders to improve their performance; the addition ratio is determined based on the composition of the specific organic binder. It can also be used in some organic coatings, with the addition ratio determined based on the composition of the specific organic coating.

[0043] Environmental and economic benefits The reagents used in the synthesis process of dimethyl silicone polyethylene ester (DSPE) and the preparation process of the modified adhesive are all environmentally friendly, providing a good environmental foundation for the manufacturing process. At the same time, the synthesis process of dimethyl silicone polyethylene ester (DSPE) and the performance improvement process of organic adhesives both have low costs, thus providing a good economic basis for its widespread application.

[0044] Taking the formulation of modified adhesives by compounding with VAE emulsion as an example, the addition of dimethyl silicone polyethylene ester (DSPE) can relatively reduce the content of VAE emulsion for the same amount of adhesive, thereby reducing the raw material cost of VAE emulsion. From another perspective, for the same amount of VAE emulsion raw material, more modified adhesives with better performance can be prepared, thereby improving the performance and yield of modified adhesives made in my country based on VAE as the basic raw material for adhesives.

[0045] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for preparing a modified adhesive, characterized in that, Includes the following steps: S1. Synthesis of modified compounds: Using polyvinyl alcohol and dimethyldichlorosilane as raw materials, compounds with the structure of formula (I) were synthesized: （I） Where n is a positive integer; S2, Compounding: The synthesized compound with the structure of formula (I) is added to the organic binder to obtain the modified binder.

2. The method for preparing the modified adhesive according to claim 1, characterized in that, In step S1, the polyvinyl alcohol is a polyvinyl alcohol solution, which is prepared by dissolving solid polyvinyl alcohol in an organic solvent.

3. The method for preparing the modified adhesive according to claim 2, characterized in that, The organic solvents include dioxane and dimethyl sulfoxide.

4. The method for preparing the modified adhesive according to claim 1, characterized in that, Step S1: Dimethyldichlorosilane is gradually added to a heated polyvinyl alcohol solution and synthesized within a preset temperature range to obtain a compound with the structure of formula (I).

5. The method for preparing the modified adhesive according to claim 4, characterized in that, Step S1, This includes: during the heating of a polyvinyl alcohol solution, adding dimethyldichlorosilane solution dropwise until the reaction temperature reaches a preset temperature, at which point the addition of dimethyldichlorosilane solution is stopped; The reaction is carried out under constant temperature and reflux for a period of time until the reaction product becomes gel-like, at which point the reaction is stopped to obtain a compound with the structure of formula (I), wherein the preset temperature is not higher than 70°C.

6. The method for preparing the modified adhesive according to claim 5, characterized in that, Step S1 further includes: after stopping the reaction, cooling the reaction product to room temperature and washing the reaction product with water until pH=6-7 to obtain the compound with the structure of formula (I).

7. The method for preparing the modified adhesive according to claim 1, characterized in that, n is an integer chosen from 1000 to 3000.

8. The method for preparing the modified adhesive according to claim 1, characterized in that, In step S2, the synthesized compound having the structure of formula (I) is compounded with vinyl acetate-ethylene copolymer emulsion in a preset ratio.

9. The method for preparing the modified adhesive according to claim 8, characterized in that, The preset ratio is no higher than 50%.

10. The method for preparing the modified adhesive according to claim 8, characterized in that, The modified binder also contains polyvinyl acetate as a dispersant.

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