Preparation method of polyvinyl butyral with low sintering residue

Abstract

The invention relates to a preparation method of polyvinyl butyral with low sintering residue. The preparation method comprises the following steps: preparing a polyvinyl alcohol solution; adding n-butyraldehyde and a nonionic macromolecular emulsifier into the polyvinyl alcohol solution; an organic acid catalyst is added, and all the components are subjected to a reaction; continuously adding an organic alkali quencher to adjust the pH value of the solution after the reaction; and carrying out suction filtration on the obtained reaction liquid, and drying white precipitate to obtain polyvinyl butyral. The method has the beneficial effects that the organic acid, the organic alkali and the organic macromolecular emulsifier which do not contain metal ions and acid radical ions and are easy to sinter and volatilize are used for replacing traditional inorganic acid, alkali and a surfactant, and the PVB resin with the low sintering residual rate is prepared; the sintering residual rate of the product is not increased, so that the method does not need to consume a large amount of water for repeated cleaning, and is more environment-friendly.

Description

Technical Field

[0001] The invention belongs to the technical field of polyvinyl butyral (PVB) preparation, and in particular relates to a method for preparing polyvinyl butyral with low sintering residue. Background Art

[0002] Polyvinyl butyral is a resin synthesized through the acetalization reaction of polyvinyl alcohol and n-butyraldehyde in the presence of an acidic catalyst. Known for its exceptional transparency, flexibility, and adhesion, PVB is commonly used as a polymer interlayer in laminated glass and is widely used in architectural, automotive safety glass, and security glass. PVB is also used as a binder and sacrificial material in electronic pastes for the manufacture of high-performance electronic ceramic devices.

[0003] When PVB is used in the manufacture of ceramic devices, it is mixed evenly with solvents, ceramic powders, and functional additives to form an electronic paste. The solvent is then removed through a specific molding process, and the PVB bonds the ceramic particles together to form a ceramic green body of a predetermined shape. PVB then decomposes into gases such as water vapor, carbon dioxide, and carbon monoxide under high temperature conditions. The ceramic particles then fuse and connect with each other, ultimately sintering to form a dense ceramic device. However, during the sintering process to form dense ceramic devices, the PVB must evaporate as completely as possible, otherwise the residue will significantly affect the electrical properties of the ceramic device. Furthermore, the sintering residue of PVB is closely related to the inorganic impurities it contains. Therefore, PVB resin with a low sintering residue rate is crucial to improving the quality of electronic pastes and electronic ceramic devices.

[0004] In some traditional PVB production processes (Patent Publication No. CN103012633B and Patent Publication No. CN104193859B), hydrochloric acid, sulfuric acid, etc. are generally used as acetalization reaction catalysts. After the reaction, alkaline substances (sodium hydroxide, potassium hydroxide) are added to neutralize the catalyst. The neutralized residue (containing a large amount of inorganic salts and metal ions) will remain in the reaction product. In other traditional PVB production processes, surfactants such as sodium dodecyl sulfate are also added to uniformly disperse n-butyraldehyde in the PVA aqueous solution and avoid the formation of undesirable reactants such as PVB agglomerates. Companies need to consume large amounts of water to repeatedly wash the product (approximately 30 tons of water are required to produce 1 ton of PVB product) to wash away residual surfactants and inorganic salts in the product. If water washing is not used, the acid radicals and metal ions contained in the inorganic salts and surfactants in the product cannot be removed by sintering, resulting in a high sintering residue rate of the product, which can significantly affect the electrical properties of ceramic devices using this product.

[0005] In summary, traditional PVB production methods not only result in significant water waste, but also produce a high sintering residue rate in the resulting PVB product. Therefore, developing a PVB resin preparation method with low water consumption and low sintering residue rate is of great value to the electronic ceramics industry. Summary of the Invention

[0006] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing polyvinyl butyral with low sintering residue.

[0007] The method for preparing the polyvinyl butyral with low sintering residue comprises the following steps:

[0008] Step 1, adding polyvinyl alcohol to ultrapure water and heating at 70-95° C. to completely dissolve the polyvinyl alcohol in the ultrapure water to prepare a 5-15 wt% polyvinyl alcohol solution;

[0009] Step 2: Cool the polyvinyl alcohol solution to 5-50° C., and sequentially add 4-12 wt % of n-butyraldehyde and 0.1-0.5 wt % of a nonionic macromolecular emulsifier having a molecular weight of 500-2000 g / mol to the cooled polyvinyl alcohol solution, stirring evenly to ensure uniform dispersion of the reactants.

[0010] Step 3, adding an organic acid catalyst with a concentration of 10 to 100 mM to the solution prepared in step 2, and reacting the components under the action of the organic acid catalyst for a specific time to obtain a post-reaction solution;

[0011] Step 4: adding an organic base quencher to the reaction solution obtained in step 3, and adjusting the pH value of the reaction solution obtained in step 3 to 8-9 to terminate the reaction process;

[0012] Step 5: Filter the reaction solution obtained in step 4 to separate the white precipitate from the reaction solution obtained in step 4, add ultrapure water to the white precipitate and wash it for a set time, then dry the white precipitate at 40-60°C to obtain Figure 1 Polyvinyl butyral product shown.

[0013] Preferably, if the heating temperature in step 1 is too low, the polyvinyl alcohol cannot be dissolved, and if the heating temperature is too high, a large amount of water will evaporate; if the concentration of the polyvinyl alcohol solution is too low, the reaction efficiency is low, and if the concentration of the polyvinyl alcohol solution is too high, the solution viscosity is too high, which easily leads to product agglomeration or agglomeration. In step 1, a mixed solution of polyvinyl alcohol and ultrapure water is heated at 90° C. to prepare a 10wt% polyvinyl alcohol solution.

[0014] Preferably, in step 2, the polyvinyl alcohol solution is cooled to 20-40° C. (when the reaction temperature is too low, the reaction efficiency of the polyvinyl alcohol solution, n-butyraldehyde, and the nonionic macromolecular emulsifier is too low and the acetalization degree is low; when the reaction temperature is too high, the reaction product of the polyvinyl alcohol solution, n-butyraldehyde, and the nonionic macromolecular emulsifier is prone to agglomeration and agglomeration). 8 wt % of n-butyraldehyde (too low a concentration of n-butyraldehyde will result in a low acetalization degree; too high a concentration of n-butyraldehyde will result in a waste of n-butyraldehyde) and 0.2 wt % of a nonionic macromolecular emulsifier with a molecular weight of 1000 g / mol (too low a molecular weight and concentration of the nonionic macromolecular emulsifier will not achieve a sufficient emulsification effect and the product will easily agglomerate and agglomerate; too high a molecular weight and concentration of the nonionic macromolecular emulsifier will result in a decrease in the purity of the product, which is not conducive to later applications) are added sequentially to the cooled polyvinyl alcohol solution.

[0015] Preferably, the nonionic macromolecular emulsifier used in step 2 includes polyacrylic acid, polyethylene glycol, polyethylene glycol monomethyl ether and polyethylene glycol fatty acid ester.

[0016] Preferably, the nonionic macromolecular emulsifier used in step 2 includes polyacrylic acid and polyethylene glycol.

[0017] Preferably, in step 3, oxalic acid, malonic acid or formic acid at a concentration of 10 to 50 mM is added to the solution prepared in step 2 (too low a catalyst concentration results in too low a reaction efficiency and a low acetalization degree; too high a concentration results in too high an impurity content in the product); the components are reacted under the action of an organic acid catalyst for 2 to 8 hours (the specific reaction time is determined by the organic acid catalyst used, the lower the organic acid catalyst concentration, the longer the reaction time, and the higher the organic acid catalyst concentration, the shorter the reaction time), to obtain a reacted solution.

[0018] Preferably, in step 3, oxalic acid at a concentration of 10 mM is added to the solution prepared in step 2.

[0019] Preferably, the organic base quencher includes organic amine acid-binding agents that do not contain metal ions and unsaturated carbon chains, such as ammonia, triethylamine, ethylenediamine, butylamine and hexylamine.

[0020] Preferably, the organic base quencher is triethylamine.

[0021] Preferably, in step 5, the white precipitate is dried at 50° C. to obtain a polyvinyl butyral product (if the temperature is too high, the product will melt and stick together; if the temperature is too low, the drying time will be too long, affecting production efficiency).

[0022] The beneficial effects of the present invention are:

[0023] The present invention has developed a method for preparing polyvinyl butyral with low water resource consumption and low sintering residue rate. The method of the present invention uses organic acids, organic bases, and organic macromolecular emulsifiers that are free of metal ions and acid radical ions and easily volatilize upon sintering to replace traditional inorganic acids, bases, and surfactants to prepare PVB resin with a low sintering residue rate. The catalyst, neutralizing agent, and macromolecular emulsifier used in the present invention can all be decomposed into gases such as water vapor, carbon monoxide, and carbon dioxide at high temperatures during sintering to form a product, and can be removed without increasing the sintering residue rate of the product. Therefore, the method of the present invention does not require the consumption of large amounts of water for repeated cleaning. The method consumes approximately 10 tons of water to produce 1 ton of PVB, making it more environmentally friendly.

[0024] The preparation method of the present invention is safe and environmentally friendly, and the product has a low sintering residue rate. It can solve the problems of high sintering residue and large water consumption of resin prepared by traditional PVB synthesis methods, and can meet the demand for slurry in the manufacture of ceramic devices. The PVB prepared by the present invention has more advantages when used in the manufacture of ceramic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a thermogravimetric graph of Example 1;

[0026] Figure 2 This is a thermogravimetric graph of Example 2;

[0027] Figure 3 This is a thermogravimetric graph of Example 3;

[0028] Figure 4 It is the thermogravimetric curve of comparative example 1;

[0029] Figure 5 It is the thermogravimetric curve of comparative example 2;

[0030] Figure 6 This is the thermogravimetric curve of Comparative Example 3. DETAILED DESCRIPTION

[0031] The present invention will be further described below with reference to the following examples. The following examples are provided only to facilitate understanding of the present invention. It should be noted that, without departing from the principles of the present invention, it is possible for a person skilled in the art to make various modifications to the present invention, and such improvements and modifications fall within the scope of the claims of the present invention.

[0032] Example 1

[0033] A method for preparing low-sintering residual polyvinyl butyral comprises the following steps: adding polyvinyl alcohol to ultrapure water and heating the water so that the polyvinyl alcohol is completely dissolved in the ultrapure water to obtain a 5wt% polyvinyl alcohol solution; cooling the polyvinyl alcohol solution to 40°C, sequentially adding 4wt% n-butyraldehyde and 0.2wt% polyethylene glycol (Mn=1000g / L) to the cooled polyvinyl alcohol solution, and stirring the mixture uniformly by mechanical stirring to ensure uniform dispersion of the reactants; adding 0.1mol / L oxalic acid to the obtained solution, reacting the components at 40°C for 4h under the action of the oxalic acid to obtain a post-reaction solution; adding triethylamine to the obtained post-reaction solution to adjust the pH value of the obtained post-reaction solution to 8-9 by the triethylamine to terminate the reaction process; suction filtering the obtained reaction solution to separate a white precipitate from the obtained reaction solution, adding ultrapure water to the white precipitate for washing for a set time, and drying the white precipitate at 50°C to obtain a PVB sample.

[0034] Sintering residue rate test: About 5 mg of the above-mentioned PVB sample was weighed and placed in a standard aluminum crucible. N2 atmosphere was introduced at a rate of 50 mL / min and a heating rate of 10 K / min to obtain a thermal gravimetric curve at 25-600 ° C. According to the thermal gravimetric curve, the final sintering residue rate of the PVB sample of this embodiment was 0.15 wt% (see Figure 1 ).

[0035] Example 2

[0036] A method for preparing low-sintering residual polyvinyl butyral comprises the following steps: adding polyvinyl alcohol to ultrapure water and heating the water so that the polyvinyl alcohol is completely dissolved in the ultrapure water to obtain a 5wt% polyvinyl alcohol solution; cooling the polyvinyl alcohol solution to 40°C, sequentially adding 4wt% n-butyraldehyde and 0.2wt% polyethylene glycol (Mn=1000g / L) to the cooled polyvinyl alcohol solution, and stirring the solution uniformly by mechanical stirring to ensure uniform dispersion of the reactants; adding 0.05mol / L oxalic acid to the obtained solution, reacting the components at 40°C for 6h under the action of the oxalic acid to obtain a post-reaction solution; adding triethylamine to the obtained post-reaction solution to adjust the pH value of the obtained post-reaction solution to 8-9 by the triethylamine to terminate the reaction process; suction filtering the obtained reaction solution to separate a white precipitate from the obtained reaction solution, adding ultrapure water to the white precipitate for washing for a set time, and drying the white precipitate at 50°C to obtain a PVB sample.

[0037] Sintering residue rate test: weigh about 5 mg of the above PVB sample and place it in a standard aluminum crucible. N2 atmosphere is introduced at a rate of 50 mL / min and the temperature is increased at a rate of 10 K / min to obtain a thermal gravimetric curve at 25-600 ° C. According to the thermal gravimetric curve, the final sintering residue rate of the PVB sample in this embodiment is 0.11 wt% (see Figure 2 ).

[0038] Example 3

[0039] A method for preparing low-sintering residual polyvinyl butyral comprises the following steps: adding polyvinyl alcohol to ultrapure water and heating the water so that the polyvinyl alcohol is completely dissolved in the ultrapure water to obtain a 6wt% polyvinyl alcohol solution; cooling the polyvinyl alcohol solution to 40°C, sequentially adding 4wt% n-butyraldehyde and 0.2wt% polyethylene glycol (Mn=1000g / L) to the cooled polyvinyl alcohol solution, and stirring the mixture uniformly by mechanical stirring to ensure uniform dispersion of the reactants; adding 0.1mol / L oxalic acid to the obtained solution, reacting the components at 40°C for 5h under the action of the oxalic acid to obtain a post-reaction solution; adding triethylamine to the obtained post-reaction solution to adjust the pH value of the obtained post-reaction solution to 8-9 by the triethylamine to terminate the reaction process; suction filtering the obtained reaction solution to separate a white precipitate from the obtained reaction solution, adding ultrapure water to the white precipitate for washing for a set time, and drying the white precipitate at 50°C to obtain a PVB sample.

[0040] Sintering residue rate test: Weigh about 5 mg of the above PVB sample and place it in a standard aluminum crucible. N2 atmosphere is introduced at a rate of 50 mL / min. The thermal gravimetric curve at 25-600°C is obtained at a heating rate of 10 K / min. According to the thermal gravimetric curve, the final sintering residue rate of the PVB sample of this embodiment is 0.21 wt% (see Figure 3 ).

[0041] Comparative Example 1

[0042] A method for preparing polyvinyl butyral comprises the following steps: adding polyvinyl alcohol to ultrapure water, and heating the water so that the polyvinyl alcohol is completely dissolved in the ultrapure water to prepare a 5wt% polyvinyl alcohol solution; cooling the polyvinyl alcohol solution to 40°C, sequentially adding 4wt% n-butyraldehyde and 0.2wt% sodium lauryl sulfate to the cooled polyvinyl alcohol solution, and stirring the mixture uniformly by mechanical stirring to ensure uniform dispersion of the reactants; adding hydrochloric acid with a concentration of 0.02mol / L to the prepared solution, and reacting the components at 25°C for 4h under the action of the hydrochloric acid to obtain a post-reaction solution; adding sodium hydroxide solution to the post-reaction solution, and adjusting the pH value of the post-reaction solution to 8-9 by the sodium hydroxide solution to terminate the reaction process; suction filtering the obtained reaction solution, separating a white precipitate from the obtained reaction solution by suction filtering, adding ultrapure water to the white precipitate, repeatedly washing and filtering the white precipitate 6-8 times, and drying the white precipitate at 50°C to obtain a PVB sample.

[0043] Sintering residue rate test: About 5 mg of the above-mentioned PVB sample was weighed and placed in a standard aluminum crucible. N2 atmosphere was introduced at a rate of 50 mL / min and a heating rate of 10 K / min to obtain a thermal gravimetric curve at 25-600 ° C. According to the thermal gravimetric curve, the final sintering residue rate of the PVB sample of this embodiment was 1.47 wt% (see Figure 4 ).

[0044] Comparative Example 2

[0045] A method for preparing polyvinyl butyral comprises the following steps: adding polyvinyl alcohol to ultrapure water, and heating the water so that the polyvinyl alcohol is completely dissolved in the ultrapure water to prepare a 5wt% polyvinyl alcohol solution; cooling the polyvinyl alcohol solution to 40°C, sequentially adding 4wt% n-butyraldehyde and 0.1wt% sodium lauryl sulfate to the cooled polyvinyl alcohol solution, and stirring the mixture uniformly by mechanical stirring to ensure uniform dispersion of the reactants; adding hydrochloric acid with a concentration of 0.01 mol / L to the prepared solution, and reacting the components at 25°C for 4h under the action of the hydrochloric acid to obtain a post-reaction solution; adding sodium hydroxide solution to the post-reaction solution, and adjusting the pH value of the post-reaction solution to 8-9 by the sodium hydroxide solution to terminate the reaction process; suction filtering the obtained reaction solution, separating a white precipitate from the obtained reaction solution by suction filtering, adding ultrapure water to the white precipitate, repeatedly washing and filtering the white precipitate 6-8 times, and drying the white precipitate at 50°C to obtain a PVB sample.

[0046] Sintering residue rate test: About 5 mg of the above-mentioned PVB sample was weighed and placed in a standard aluminum crucible. N2 atmosphere was introduced at a rate of 50 mL / min and a heating rate of 10 K / min to obtain a thermal gravimetric curve at 25-600 ° C. According to the thermal gravimetric curve, the final sintering residue rate of the PVB sample of this embodiment was 1.28 wt% (see Figure 5 ).

[0047] Comparative Example 3

[0048] A method for preparing polyvinyl butyral comprises the following steps: adding polyvinyl alcohol to ultrapure water, and heating the water so that the polyvinyl alcohol is completely dissolved in the ultrapure water to prepare a 5wt% polyvinyl alcohol solution; cooling the polyvinyl alcohol solution to 5°C, adding 4wt% n-butyraldehyde to the cooled polyvinyl alcohol solution, and stirring the solution uniformly by mechanical stirring to ensure uniform dispersion of all reactants; adding hydrochloric acid with a concentration of 0.1 mol / L to the prepared solution, reacting all components at 5°C for 3 hours under the action of the hydrochloric acid to obtain a post-reaction solution, heating the reaction solution to 60°C, and continuing the reaction for 3 hours; adding sodium hydroxide solution to the post-reaction solution, and adjusting the pH value of the post-reaction solution to 8-9 by the sodium hydroxide solution to terminate the reaction process; suction filtering the obtained reaction solution, separating a white precipitate from the obtained reaction solution by suction filtering, adding ultrapure water to the white precipitate, repeatedly washing and filtering the white precipitate 6-8 times, and drying the white precipitate at 50°C to obtain a PVB sample.

[0049] Sintering residue rate test: About 5 mg of the above-mentioned PVB sample was weighed and placed in a standard aluminum crucible. N2 atmosphere was introduced at a rate of 50 mL / min and a heating rate of 10 K / min to obtain a thermal gravimetric curve at 25-600 ° C. According to the thermal gravimetric curve, the final sintering residue rate of the PVB sample of this embodiment was 0.58 wt% (see Figure 6 ).

Claims

1. A method for preparing polyvinyl butyral with low sintering residue, characterized in that: The following steps are involved: Step 1: Add polyvinyl alcohol to ultrapure water and heat at 70-95° C. to completely dissolve the polyvinyl alcohol in the ultrapure water to prepare a 5-15 wt% polyvinyl alcohol solution; Step 2: Cool the polyvinyl alcohol solution to 5-50° C., and sequentially add 4-12 wt % of n-butyraldehyde and 0.1-0.5 wt % of a nonionic macromolecular emulsifier having a molecular weight of 500-2000 g / mol to the cooled polyvinyl alcohol solution, and stir evenly. Step 3: adding an organic acid catalyst with a concentration of 10 to 100 mM to the solution prepared in step 2, and reacting the components under the action of the organic acid catalyst for a specific time to obtain a post-reaction solution; Step 4: adding an organic base quencher to the reaction solution obtained in step 3 to adjust the pH value of the reaction solution obtained in step 3 to 8-9; Step 5: Filter the reaction solution obtained in step 4 to separate a white precipitate from the reaction solution obtained in step 4, add ultrapure water to the white precipitate and wash it for a set time, then dry the white precipitate at 40-60° C. to obtain a polyvinyl butyral product.

2. The method for preparing polyvinyl butyral with low sintering residue according to claim 1, characterized in that: In step 1, a mixed solution of polyvinyl alcohol and ultrapure water is heated at 90° C. to prepare a 10 wt % polyvinyl alcohol solution.

3. The method for preparing polyvinyl butyral with low sintering residue according to claim 1 or 2, characterized in that: In step 2, the polyvinyl alcohol solution is cooled to 20-40° C., and 8 wt % of n-butyraldehyde and 0.2 wt % of a nonionic macromolecular emulsifier having a molecular weight of 1000 g / mol are sequentially added to the cooled polyvinyl alcohol solution.

4. The method for preparing polyvinyl butyral with low sintering residue according to claim 1, characterized in that: The nonionic macromolecular emulsifier used in step 2 includes polyacrylic acid, polyethylene glycol, polyethylene glycol monomethyl ether and polyethylene glycol fatty acid ester.

5. The method for preparing polyvinyl butyral with low sintering residue according to claim 4, characterized in that: The nonionic macromolecular emulsifier used in step 2 includes polyacrylic acid and polyethylene glycol.

6. The method for preparing polyvinyl butyral with low sintering residue according to claim 1, characterized in that: In step 3, oxalic acid, malonic acid or formic acid at a concentration of 10 to 50 mM is added to the solution prepared in step 2; and the components react under the action of an organic acid catalyst for 2 to 8 hours to obtain a post-reaction solution.

7. The method for preparing polyvinyl butyral with low sintering residue according to claim 6, characterized in that: In step 3, oxalic acid having a concentration of 10 mM is added to the solution prepared in step 2.

8. The method for preparing polyvinyl butyral with low sintering residue according to claim 1, characterized in that: The organic base quencher includes ammonia water, triethylamine, ethylenediamine, butylamine and hexylamine.

9. The method for preparing polyvinyl butyral with low sintering residue according to claim 8, characterized in that: The organic base quencher is triethylamine.

10. The method for preparing polyvinyl butyral with low sintering residue according to claim 1, characterized in that: In step 5, the white precipitate is dried at 50° C. to obtain a polyvinyl butyral product.

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