JP2010106234A - Method of producing polyvinyl acetal resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of producing a polyvinyl acetal resin capable of suppressing heat degradation in a temperature-raising step and generation of byproducts without using an acid catalyst, and obtaining the polyvinyl acetal resin having a high degree of acetalization in a short time, and to provide the method of producing the polyvinyl acetal resin capable of efficiently producing without giving rise to occlusion of resin in a production line during or after reaction even if a raw material is a highly concentrated polymer solution. <P>SOLUTION: The method of producing the polyvinyl acetal resin comprises contacting a raw material mixture liquid containing a polyvinyl alcohol resin and an aldehyde with a high temperature and high pressure fluid in a flowing type reaction apparatus to react them at a temperature of 100-400°C and at a pressure of 0.5-100 MPa. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention is the production of a polyvinyl acetal resin capable of obtaining a polyvinyl acetal resin having a high degree of acetalization in a short period of time without using an acid catalyst and suppressing thermal deterioration and by-product formation in the temperature rising process. Regarding the method. The present invention also relates to a method for producing a polyvinyl acetal resin that can be efficiently produced without causing clogging of the resin during or after the reaction even if the raw material is a high-concentration polymer solution.

Polyvinyl acetal resins are used for various purposes such as laminated films for laminated glass, metal processing wash primers, various paints, adhesives, resin processing agents, and ceramic binders. In recent years, their use has expanded to electronic materials. Yes. Among these, polyvinyl butyral resin is particularly suitably used for an interlayer film for laminated glass and the like because it is excellent in film forming property, transparency, impact energy absorption, and adhesion to glass.

As disclosed in Patent Document 1, the polyvinyl acetal resin is usually produced by dehydrating and condensing polyvinyl alcohol and an aldehyde compound in the presence of an acid catalyst such as hydrochloric acid. Patent Document 2 discloses a method for producing a polyvinyl butyral resin in which polyvinyl alcohol and butyraldehyde are mixed in an aqueous solution in the presence of an acid catalyst with a constant stirring power.

However, in the method for producing a polyvinyl acetal resin disclosed in Patent Documents 1 and 2, since an acid catalyst is used, a process for neutralizing an acid is particularly required when used for an electronic material application. A very complicated process for removing impurities in the resin by washing the halide ions of the catalyst remaining in the resin and alkali ions used for neutralization is necessary.
On the other hand, when polyvinyl alcohol and an aldehyde are reacted without using an acid catalyst such as hydrochloric acid, a degree of acetalization of about 40 mol% is required although a degree of acetalization of 70 mol% or more is practically required. Only a polyvinyl acetal-based resin having Furthermore, when heated to a high temperature in order to promote the acetalization reaction, deterioration such as the main chain of the resin being broken may occur and the resin may be colored.

Patent Document 3 discloses a method for producing polyvinyl acetal by reacting polyvinyl alcohol and an aldehyde without using an acid catalyst such as hydrochloric acid, utilizing the catalytic action of a high-temperature and high-pressure fluid such as a supercritical fluid. However, in the method using a high-temperature and high-pressure fluid instead of the acid catalyst disclosed in Patent Document 3, even though a polyvinyl acetal resin having a sufficient degree of acetalization can be obtained, coloring due to deterioration of the resin may occur. There was a problem that by-products such as modified aldehydes were generated.

Japanese Patent Laid-Open No. 6-1853 JP-A-11-349629 WO2003 / 033548

The present invention is the production of a polyvinyl acetal resin capable of obtaining a polyvinyl acetal resin having a high degree of acetalization in a short period of time without using an acid catalyst and suppressing thermal deterioration and by-product formation in the temperature rising process. It aims to provide a method. Moreover, even if a raw material is a high concentration polymer solution, the manufacturing method of the polyvinyl acetal resin which can be manufactured efficiently, without raise | generating the line clogging of the resin during reaction or after reaction is provided.

The present invention 1 is a polyvinyl acetal in which a raw material mixture containing a polyvinyl alcohol-based resin and an aldehyde is brought into contact with a high-temperature and high-pressure fluid in a flow reactor and reacted at a temperature of 100 to 400 ° C. and a pressure of 0.5 to 100 MPa. It is a manufacturing method of a resin.
The present invention 2 is a polyvinyl alcohol in which a raw material mixed solution containing a polyvinyl acetate resin and an aldehyde is brought into contact with a high-temperature high-pressure fluid in a flow-type reaction apparatus and reacted at a temperature of 100 to 400 ° C. and a pressure of 0.5 to 100 MPa. This is a method for producing an acetal resin.
The present invention is described in detail below.

In the method for producing a polyvinyl acetal resin from a polyvinyl alcohol resin or a polyvinyl acetate resin and an aldehyde, the present inventors cause coloration due to deterioration of the resin when a high-temperature high-pressure fluid is used instead of an acid catalyst. The reason for the generation of by-products such as modified aldehydes was because of the use of a reaction vessel with poor heat transfer efficiency such as an autoclave, and it took a long time to reach the target temperature. I found out. Then, a liquid mixture containing a polyvinyl alcohol resin or polyvinyl acetate resin and an aldehyde is brought into contact with a high-temperature and high-pressure fluid in a flow-type reaction apparatus to be acetalized while rapidly raising the temperature. It has been found that a polyvinyl acetal-based resin having a high degree of acetalization can be obtained in a short time while suppressing thermal degradation and by-product formation. Furthermore, when the raw material is high concentration, the resin becomes a lump in the reaction part and clogs the line, but by including an instrument having a stirring function such as a static mixer in the mixing part, the line clogging can be eliminated, The present inventors have found that it can be produced continuously and have reached the present invention.

In the method for producing a polyvinyl acetal resin of the present invention, a raw material mixture containing a polyvinyl alcohol resin or a polyvinyl acetate resin and an aldehyde is brought into contact with a high-temperature high-pressure fluid in a flow reactor, and the temperature is 100 to 400 ° C. And a step of reacting at a pressure of 0.5 to 100 MPa.

As the polyvinyl alcohol-based resin, for example, a conventionally known polyvinyl alcohol-based resin such as a resin produced by saponifying polyvinyl acetate with an alkali, an acid, aqueous ammonia, or the like can be used.
The polyvinyl alcohol-based resin may be completely saponified. However, it is necessary that the polyvinyl alcohol-based resin is completely saponified if at least one unit having a meso- and racemic-positioned hydroxyl group at least in one position of the main chain is present. Alternatively, a partially saponified polyvinyl alcohol resin may be used. In addition, as the polyvinyl alcohol-based resin, a copolymer of vinyl alcohol and a monomer copolymerizable with vinyl alcohol, such as ethylene-vinyl alcohol copolymer resin and partially saponified ethylene-vinyl acetate copolymer resin, may be used. Can do.
Examples of the polyvinyl acetate resin include an ethylene-vinyl acetate copolymer.

Examples of the aldehyde compound include linear, branched, cyclic saturated, cyclic unsaturated, or aromatic aldehyde compounds having 1 to 19 carbon atoms. Examples of the aldehyde compound include formaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, isobutyraldehyde, tert-butyraldehyde, benzaldehyde, cyclohexyl aldehyde, and the like. The said aldehyde compound may be used independently and may use 2 or more types together. The aldehyde compound may be one in which one or more hydrogen atoms are substituted with halogen or the like.

The blending amount of the aldehyde with respect to the polyvinyl alcohol-based resin or the polyvinyl acetate-based resin is preferably the same as the theoretical reaction amount at the lower limit, and 30 times as high as the theoretical reaction amount. When the blending amount of the aldehyde is less than equal to the theoretical reaction amount, the reaction does not proceed and the degree of acetalization of the obtained polyvinyl acetal resin may be insufficient. Even if the blending amount of the aldehyde exceeds 30 times the theoretical reaction amount, it may not contribute to the improvement of the degree of acetalization, leading to an increase in cost. Moreover, when there are too many compounding quantities of the said aldehyde, it will also become a cause which produces | generates a by-product. The more preferable upper limit of the compounding amount of the aldehyde is 12 times the theoretical reaction amount, and the more preferable upper limit is 3 times the theoretical reaction amount.

The polyvinyl alcohol resin or the polyvinyl acetate resin and the aldehyde are subjected to the reaction in a mixed solution state. The raw material mixture may be in the form of a solution or suspension using a medium such as water.

In the acetalization reaction of the polyvinyl alcohol-based resin or the polyvinyl acetate-based resin, the resin may be insolubilized or inhomogeneously precipitated as the reaction proceeds. In the resin thus deposited, since the hydroxyl group to be acetalized is confined inside the resin, the progress of the acetalization reaction is hindered, and the atmospheric pressure reaction can only achieve a degree of acetalization of about 40 mol%. However, the contact with the high-temperature and high-pressure fluid allows the aldehyde to penetrate into the precipitated resin, so that a high degree of acetalization that cannot be achieved at normal pressure can be achieved.

Examples of the high-temperature and high-pressure fluid include water, methanol, carbon dioxide, nitrogen, helium, and argon. The above high-temperature and high-pressure fluids may be used alone or in combination as a mixture. Of these, water, methanol, carbon dioxide, or a mixture thereof is preferable.

The lower limit of the temperature when the raw material mixture is brought into contact with the high-temperature high-pressure fluid for reaction is 100 ° C., and the upper limit is 400 ° C. When the reaction temperature is less than 100 ° C., the reaction does not proceed sufficiently, and a polyvinyl acetal resin having a sufficient degree of acetalization may not be obtained or may be colored. When the reaction temperature exceeds 400 ° C., the main chain is cleaved and the resin is deteriorated, and the resin is colored. A preferable upper limit of the reaction temperature is 350 ° C., and a more preferable upper limit is 300 ° C.

The lower limit of the pressure at the time of making the said raw material liquid mixture contact and react with the said high temperature / high pressure fluid is 0.5 MPa, and an upper limit is 100 MPa. When the pressure of the reaction fluid is less than 0.5 MPa, the reaction does not proceed sufficiently, and a polyvinyl acetal resin having a sufficient degree of acetalization cannot be obtained. A preferable lower limit of the reaction fluid is 10 MPa.

The method of bringing the mixed liquid into contact with a high-temperature and high-pressure fluid in a flow reactor is a pressure-resistant reaction of a solution or suspension containing a polyvinyl alcohol resin or a polyvinyl acetate resin and an aldehyde with a liquid feed pump. Introduce into the pipe line, inject high-temperature fluid into the pressure-resistant reaction pipe line with a liquid feed pump, join the above lines in the reaction section, and pressurize by controlling the discharge amount of liquid at the line outlet The method is preferred.
The flow reaction apparatus may have a mechanism for heating and cooling a part of the line to an appropriate temperature.

Since the reaction proceeds rapidly in the reaction section where the raw material line and the high-temperature high-pressure fluid merge, the resin may precipitate rapidly. In this case, the deposited resin is clogged in the reaction part or line, and the production is stopped. Since the higher the concentration of the raw material, the easier it is to precipitate, the production efficiency does not increase. Therefore, in the method for producing the polyvinyl acetal resin of the present invention, it is preferable to stir and mix the raw material mixture and the high temperature and high pressure fluid in a tube containing a stirrer. Specifically, by including a stirrer in the reaction section, the precipitate can be atomized by stirring while rapidly raising the temperature even when the raw material is in a high concentration. Can be eliminated.

As the stirrer, a so-called stationary mixer (static mixer) without a drive unit, which is disposed in the flow path in the reaction unit, can be adopted, and the shape and number of elements constituting this may be arbitrarily selected. .

The preferable lower limit of the degree of polymerization of the polyvinyl acetal resin produced using the method for producing the polyvinyl acetal resin of the present invention is 200, and the preferred upper limit is 5000. If the degree of polymerization of the polyvinyl acetal resin is less than 200, the strength when formed into a film may be lowered. When the polymerization degree of the polyvinyl acetal resin exceeds 2000, the hot melt viscosity becomes too high, and the moldability may be deteriorated. The more preferable lower limit of the degree of polymerization of the polyvinyl acetal resin is 300, and the more preferable upper limit is 2000.

According to the present invention, a polyvinyl acetal resin having a high degree of acetalization can be obtained in a short period of time by suppressing thermal deterioration and by-product formation in the temperature rising process without using an acid catalyst in a flow supercritical reactor. The manufacturing method of the polyvinyl acetal type resin which can be obtained can be provided. In addition, it is possible to provide a method for producing a polyvinyl acetal resin that can be efficiently produced without causing clogging of the resin during or after the reaction even if the raw material is a high-concentration polymer solution.

It is a schematic diagram which shows an example of the flow-type reaction apparatus of this invention. It is a schematic diagram which shows the structure of the junction part in the reaction part which installed the static mixer.

Hereinafter, embodiments of the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

(Examples 1-7, Comparative Examples 2-3)
Polyvinyl butyral was produced using the flow reactor shown in FIG. The flow reactor shown in FIG. 1 feeds the raw materials A and B to the lines A and B with a pressure pump and a feeder and heats the raw material B in the line B to a high temperature while maintaining the high pressure state. It is an apparatus that can cause the raw material A in the line A to collide with the raw material A in the line A at the junction of A and the line B, rapidly raise the temperature of the raw material A, and continuously cause a reaction in the line.

A mixture obtained by stirring the raw materials shown in Table 1 in a separable flask was charged into the raw material feeder, water into tank A, and heating fluid into tank B. Each was sent into a flow reactor by a pressure pump, and a reaction experiment was conducted under the conditions shown in the table. The pressure in the distribution line was adjusted with a pressure regulating valve. At this time, the volume from the junction to the outlet of the reaction unit was 200 mL (400 mL only in Example 2), and static mixers as shown in FIG. 2 were installed in Examples 5 to 7 and Comparative Example 3 inside the reaction unit. In Examples 1 to 4 and Comparative Example 2, it was carried out without installing a static mixer.
As the raw material polyvinyl alcohol, those having a saponification degree of 99% and a polymerization degree of 500 were used, and as the raw material polyvinyl acetate, those having a saponification degree of 0% and a polymerization degree of 1000 were used.

(Comparative Example 1)
0.4 g of n-butyraldehyde was added to 5 g of a 10% by weight aqueous solution of polyvinyl alcohol having a saponification degree of 99% and a polymerization degree of 500, and stirred for 5 minutes using a stirrer to obtain a mixed solution. The obtained liquid mixture was put into a pressure-resistant 10 mL volume reaction tube and purged with nitrogen, then covered, and put into a sand bath heated to 250 ° C. The pressure in the reaction tube at this time was 10 MPa. Ten minutes later, the reaction tube was taken out from the sand bath, cooled, and then the resin dispersion was taken out and dried to obtain a resin.

(Evaluation)
The following evaluation was performed about manufacture of the polyvinyl butyral resin in an Example and a comparative example, and the obtained polyvinyl butyral resin.
The results are shown in Table 1.

(1) After removing the polyvinyl butyral resin dispersion from the butyral degree recovery tank and drying it, the resulting resin is dissolved in dimethyl sulfoxide, precipitated in water three times, sufficiently dried, and then deuterated dimethyl It was redissolved in sulfoxide, and the degree of butyralization was measured by ¹ H-NMR measurement.

(2) Evaluation of coloring degree The polyvinyl butyral resin dispersion was taken out from the collection tank, and the coloring of the liquid and the resin was visually evaluated. If it was white, it was marked as x if it was colored like ◯, yellow or brown.

(3) Productivity evaluation The flow reaction was continuously performed, and the time until the point where the resin line clogging occurred and the production was interrupted was compared.

According to the present invention, without using an acid catalyst, a polyvinyl acetal resin that can suppress a heat deterioration and a by-product formation in a temperature rising process and can obtain a polyvinyl acetal resin having a high degree of acetalization in a short time. The manufacturing method of can be provided. In addition, it is possible to provide a method for producing a polyvinyl acetal resin that can be efficiently produced without causing clogging of the resin during or after the reaction even if the raw material is a high-concentration polymer solution.

1 Raw material tank A
2 Syringe feeder 3 Raw material tank B
4 Line A
5 Line B
6 Pressurizing pump 7 Heater 8 Fluid heating unit 9 Reaction unit 10 Cooling unit 11 Recovery tank A
12 Collection tank B
13 Pressure regulating valve

Claims (4)

A polyvinyl acetal characterized in that a raw material mixture containing a polyvinyl alcohol resin and an aldehyde is brought into contact with a high-temperature and high-pressure fluid in a flow reactor and reacted at a temperature of 100 to 400 ° C. and a pressure of 0.5 to 100 MPa. Method for production of resin. Polyvinyl acetate characterized by bringing a raw material mixture containing a polyvinyl acetate resin and an aldehyde into contact with a high-temperature and high-pressure fluid in a flow reactor and reacting at a temperature of 100 to 400 ° C. and a pressure of 0.5 to 100 MPa. A method for producing an acetal resin. The method for producing a polyvinyl acetal resin according to claim 1 or 2, wherein the raw material mixture and the high-temperature high-pressure fluid are stirred and mixed in a tube containing a stirrer. The method for producing a polyvinyl acetal resin according to claim 1, 2 or 3, wherein the high-temperature and high-pressure fluid is water, methanol, carbon dioxide, or a mixture thereof.

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