JPH0931124A - Production of polyvinyl acetal, polyvinyl acetal, interlayer for laminated glass and laminated glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a polyvinyl acetal within a short production time to obtain an interlayer for a laminated glass by using a polyvinyl butyral obtained by the above process and to obtain a laminated glass. SOLUTION: This process for producing a polyvinyl acetal comprises condensing polyvinyl alcohol with an aldehyde compound, wherein the polyvinyl alcohol used is one having a 1,2-glycol bond content of at most 1.70mol%. Polyvinyl butyral, among polyvinyl acetals obtained by this process, is used to obtain an interlayer for a laminated glass and a laminated glass in the manner similar to the conventional.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a polyvinyl acetal, and more particularly to a method for producing a polyvinyl acetal capable of shortening the production time and a method for producing a polyvinyl acetal having a relatively large particle size.

Further, the present invention relates to a polyvinyl acetal obtained by the above-mentioned method for producing polyvinyl acetal, an interlayer film for laminated glass using polyvinyl butyral among the polyvinyl acetals, and a laminated glass using the interlayer film for laminated glass. .

[0003]

2. Description of the Related Art Polyvinyl acetals such as polyvinyl butyral are widely used as a raw material resin for safety glass interlayer films, paints, adhesives and the like. This kind of polyvinyl acetal is mainly produced by a precipitation method and a solution method.

Taking the production of polyvinyl butyral as an example, in the precipitation method, butyraldehyde is added to an aqueous solution of polyvinyl alcohol in the presence of an acid catalyst, and the condensation reaction is generally carried out at a relatively low temperature of 20 ° C. or lower to give polyvinyl butyral. Precipitation is performed, and then the temperature is raised to carry out an aging reaction (see, for example, JP-A-56-82806).

In the solution method, polyvinyl alcohol, an acid catalyst and butyraldehyde are added to an organic solvent such as isopropyl alcohol, and a condensation reaction and an aging reaction are performed at a relatively high temperature to obtain a solution of polyvinyl butyral, and this solution is added to this solution. A non-solvent such as water is added to precipitate polyvinyl butyral.

[0006]

However, in the production of polyvinyl acetal by the conventional precipitation method, the aging reaction is performed after the condensation reaction to stabilize the polyvinyl acetal, but in this case, good quality is obtained. In order to
The precipitate must be stirred in water for a long time to carry out the aging reaction, which causes a problem that the production time becomes long.

Further, in the solution method, saponification of polyvinyl alcohol is likely to occur under acidic conditions, and the concentration of hydrochloric acid must be lower than that in the precipitation method. Therefore, the condensation reaction and the aging reaction require a long time, and in this case as well. There is a problem that the manufacturing time becomes long.

Further, in the precipitation method, polyvinyl alcohol having a high saponification degree is used, and in order to obtain such an aqueous solution of polyvinyl alcohol in a short time, it is advantageous to raise the temperature of water into which the polyvinyl alcohol is introduced. However, when the water temperature is high (about 50 ° C. or higher), the polyvinyl alcohol is likely to be in a lump (mamako) and, on the contrary, is difficult to dissolve.

Therefore, a method is adopted in which the temperature of the water into which the polyvinyl alcohol is added is lowered (about 40 ° C. or less) to prevent the formation of lumps, and then the temperature is raised to 90 ° C. or more to completely dissolve it. However, in this case, it takes a long time to raise the temperature to 90 ° C. or higher, which causes a problem that the manufacturing time becomes long.

Further, in the precipitation method, the condensation reaction is generally carried out at a relatively low temperature of 20 ° C. or lower in order to precipitate the polyvinyl acetal particles so as not to coarsen or agglomerate and to obtain a product of uniform quality. I'm gone,
In this case, the obtained polyvinyl acetal particles become fine, and there arises a problem that fine powder rises up during handling work, and bite into the screw during extrusion molding becomes poor.

The present invention solves the above problems, and a first object thereof is to provide a method for producing a polyvinyl acetal which can shorten the time of the aging reaction mainly in the precipitation method and the solution method.

A second object of the present invention is to provide a method for producing polyvinyl acetal capable of shortening the preparation time of the polyvinyl alcohol aqueous solution in the precipitation method.

A third object is to provide a method for producing a polyvinyl acetal having a relatively large particle size in the precipitation method, preferably having an average particle size of 80 μm or more.

A fourth object is to provide a polyvinyl acetal obtained by any one of the above-mentioned methods for producing polyvinyl acetal.

A fifth object is to provide an interlayer film for laminated glass using polyvinyl butyral among the above polyvinyl acetals and a laminated glass using the interlayer film for laminated glass.

[0016]

The first object of the present invention is to provide a method for producing polyvinyl acetal by condensing polyvinyl alcohol and an aldehyde compound.
It can be achieved by using polyvinyl alcohol having a glycol bond content of 1.70 mol% or less (the invention of claim 1).

The second object is to prepare a polyvinyl acetal by condensing an aqueous polyvinyl alcohol solution and an aldehyde compound (precipitation method).
-Polyvinyl alcohol having a glycol bond content of 1.70 mol% or less is used.
It can be achieved by pouring the mixture into warm water of 65 ° C. and then dissolving at 90 ° C. or higher to obtain the polyvinyl alcohol aqueous solution (invention of claim 2).

The third object is to prepare a polyvinyl acetal by condensing an aqueous solution of polyvinyl alcohol and an aldehyde compound (precipitation method).
-This can be achieved by using a polyvinyl alcohol having a glycol bond content of 1.70 mol% or less, performing a condensation reaction at 20 ° C or less to precipitate polyvinyl acetal, and then performing an aging reaction at 30 ° C or more ( Invention of claim 3).

The fourth object is achieved by the polyvinyl acetal obtained by any one of the above-mentioned methods for producing polyvinyl acetal (the invention of claim 4).

The fifth object is achieved by an interlayer film for laminated glass and a laminated glass using polyvinyl butyral among the above polyvinyl acetals (inventions of claims 5 and 6).

The average degree of polymerization and the degree of saponification of the polyvinyl alcohol used in the inventions of claims 1 to 3 are selected according to the intended use of the polyvinyl acetal to be produced, as in the conventional production method. For example, when manufacturing polyvinyl butyral used for an interlayer film for laminated glass, the average degree of polymerization is 8
It is preferably from 00 to 3000. The saponification degree is
To obtain highly transparent polyvinyl butyral, 95
It is preferably at least mol%, more preferably at least 98 mol%.

And, in the inventions of claims 1 to 3,
-It is necessary to use polyvinyl alcohol having a glycol bond content of 1.70 mol% or less, which is significantly different from the conventional production method. Here, the 1,2-glycol bond amount is measured by a nuclear magnetic resonance spectrum method (NMR method). The reason for using such a specific polyvinyl alcohol is as follows.

That is, as in the conventional manufacturing method,
When polyvinyl alcohol having a 2-glycol bond amount of more than 1.70 mol% is used, in the invention of claim 1,
This is because the effect of shortening the aging reaction time is reduced.

Further, as in the conventional manufacturing method, 1,2-
This is because when polyvinyl alcohol having a glycol bond amount of more than 1.70 mol% is used, the effect of shortening the preparation time of the polyvinyl alcohol aqueous solution in the invention of claim 2 becomes small.

Further, as in the conventional manufacturing method, 1,2-
This is because, when polyvinyl alcohol having a glycol bond amount of more than 1.70 mol% is used, it is difficult in the invention of claim 3 to have a relatively large particle size and an average particle size of 80 μm or more.

The aldehyde compound used in the inventions of claims 1 to 3 is selected according to the intended use of the polyvinyl acetal to be produced, as in the conventional production method. For example, when producing polyvinyl butyral used for an interlayer film for laminated glass, butyraldehyde is used as the aldehyde compound.

In addition, formaldehyde, acetaldehyde, benzaldehyde, crotonaldehyde, glyoxazole aldehyde, p-hydroxybenzaldehyde, dihydroxybenzaldehyde,
Aldehyde compounds such as 2-ethylhexyl aldehyde, propionaldehyde, phenyl aldehyde, isobutyraldehyde, furfural aldehyde, acrolein aldehyde, chloral aldehyde, p-azidobenzaldehyde, cyclohexyl aldehyde and chlorobenzaldehyde are used.

In the inventions of claims 1 to 3, an acid catalyst is generally used as the catalyst for condensing the polyvinyl alcohol and the aldehyde compound, and specifically, an inorganic acid such as sulfuric acid, nitric acid, hydrochloric acid or p- An organic acid such as toluene sulfonic acid is used. The amount of these acid catalysts used is such that the concentration (concentration of acid catalyst) at the end of the condensation reaction is 0.5 to
The amount is preferably 5% by weight.

A predetermined amount of these acid catalysts may be added all at once, but in the case of the precipitation method, it is preferable to add them in a suitable number of times in order to precipitate fine polyvinyl acetal particles. For example, when hydrochloric acid is used as the acid catalyst, 1/20 to 1/1 / of the total required amount before precipitation of the precipitate
It is preferable to add 3 and the rest after the precipitation of the precipitate. Further, in the case of the solution method, it is preferable in terms of efficiency to add all the predetermined amounts at the beginning of the reaction.

According to the first to third aspects of the invention, in the precipitation method, the polyvinyl alcohol is dissolved in warm water to prepare an aqueous solution.
90 ° C or higher, preferably 93, after being poured into 5 ° C warm water
It is preferable to elevate the temperature to ℃ or more and dissolve at this temperature for 1 hour or more. If the temperature of the hot water into which the polyvinyl alcohol is added is less than 45 ° C, the effect of shortening the dissolution time becomes small, and conversely, if the temperature of the hot water exceeds 65 ° C, the polyvinyl alcohol becomes lumpy and the dissolution time becomes longer.

According to the first aspect of the invention, in the solution method, the above-mentioned polyvinyl alcohol is dissolved in an organic solvent such as isopropyl alcohol or a mixed solvent with water to obtain a solvent solution.

In the inventions of claims 1 to 3, the concentration of the polyvinyl alcohol aqueous solution (precipitation method) or the solvent solution (solution method) is not particularly limited as long as it is a concentration capable of acetalization by a condensation reaction. 3 to 15% by weight.

The amount of the above-mentioned aldehyde compound used is
In either case of the precipitation method or the solution method, it is appropriately determined according to the degree of acetalization of the polyvinyl acetal to be produced, but when it is used for an interlayer film for laminated glass, the degree of acetalization (degree of butyralization) is 60 to It is preferable to use butyraldehyde in an amount of 75 mol%, for which, for 100 parts by weight of polyvinyl alcohol,
It is desirable to add 49 to 74 parts by weight of butyraldehyde.

According to the invention of claim 1, for example, in order to produce polyvinyl butyral, in the precipitation method, an acid catalyst is added to the above-mentioned specific polyvinyl alcohol aqueous solution, and then the reaction system is cooled to 20 ° C. or lower, and butyl is added thereto. A method in which an aldehyde is added to cause a condensation reaction to cause precipitation of polyvinyl butyral is preferably adopted.

The temperature of the reaction system is kept low in this way.
In order to precipitate the precipitate in the form of fine particles or powder and to obtain a product of uniform quality, the lower limit of the temperature may be a temperature at which the reaction system does not freeze, and is not particularly limited. However, a temperature of -6 ° C or higher is usually adopted.

Then, after the condensation reaction of polyvinyl butyral is completed, an aging reaction is carried out to stabilize polyvinyl butyral. In this case, the reaction system is heated to 3
It is preferable to carry out the aging reaction while keeping the temperature at 0 ° C. or higher for several hours.

The reason for carrying out the aging reaction while keeping the temperature of the reaction system at 30 ° C. or higher is to make the particle size relatively large (80 μm or more in average particle size) and to sufficiently advance the aging reaction. The upper limit of the temperature is not particularly limited as long as water does not boil, but a temperature of 90 ° C. or lower is usually adopted.

Then, the acid catalyst was neutralized with an alkali, filtered to take out polyvinyl butyral, and washed by a conventional method.
Purification and drying are performed to produce powdery polyvinyl butyral.

On the other hand, in the invention of claim 1, in the solution method, the specific polyvinyl alcohol, the acid catalyst and butyraldehyde are added to a mixed solvent of an organic solvent such as isopropyl alcohol or water, and then the reaction system is added. 40-9
A method of raising the temperature to 0 ° C. and conducting the condensation reaction and the aging reaction for several hours is suitably adopted. Then, after that, a non-solvent such as water is added to the reaction solution to precipitate polyvinyl butyral, and washing, purification, and drying are performed by a conventional method to produce powdery polyvinyl butyral.

As described above, in the method for producing polyvinyl acetal by condensing polyvinyl alcohol and an aldehyde compound (mainly the precipitation method and the solution method),
When polyvinyl alcohol having a 1,2-glycol bond content of 1.70 mol% or less is used, the aging reaction time is mainly shortened. Although its mechanism of action has not been clarified,
It is inferred as follows.

First, an aldehyde compound undergoes a condensation reaction with a hydroxyl group of polyvinyl alcohol to form an acetal ring. This condensation reaction is an equilibrium reaction, and the degree of acetalization becomes almost constant in the equilibrium state where the reaction has progressed to some extent. .

At this time, when the aging reaction is carried out at a relatively high temperature, the acetal ring is changed, and the racemic acetal rings whose configurations are opposite to each other along the main chain are
Along the main chain, they change to the same stable meso-type acetal ring, while the hydroxyl group changes from isotactic to stable syndiotactic conformation, and its chain length increases. As a result, the obtained polyvinyl acetal is changed into a more stable and rigid resin.
As described above, the meso-type ratio of the structure of the acetal ring can be used as a scale representing the degree of the aging reaction.

Here, 1,2-
If a glycol bond is present, the hydroxyl group in the 1,2-glycol bond reacts with the aldehyde compound but cannot form an acetal ring, so the aldehyde compound once reacted can be dissociated to form an acetal ring. Re-reacts with 1,3-glycol bonds.

Therefore, the presence of the 1,2-glycol bond causes inhibition of the acetalization reaction. Also, 1,
The 2-glycol bond makes the structure of polyvinyl alcohol irregular and also functions as a soft bending point in terms of physical properties, so that it inhibits the growth of the chain length of the hydroxyl group and the change of the acetal ring, resulting in acetalization. The reaction and aging reactions take longer.

Therefore, the polyvinyl alcohol 1,
When the amount of 2-glycol bond is reduced to 1.70 mol% or less, the acetalization reaction is accelerated, and the structural changes of the acetal ring and the hydroxyl group are accelerated, and as a result, the aging reaction time is mainly shortened. it is conceivable that.

In the method (precipitation method) for producing polyvinyl acetal by condensing an aqueous solution of polyvinyl alcohol and an aldehyde compound as in the invention of claim 2, the 1,2-glycol bond amount is 1.70 mol. % Of polyvinyl alcohol is used, and when this polyvinyl alcohol is poured into water at 45 to 65 ° C. and then melted at 90 ° C. or higher to obtain an aqueous solution, the preparation time of the polyvinyl alcohol aqueous solution is shortened. Although its mechanism of action has not been clarified, it is presumed as follows.

When polyvinyl alcohol is dissolved in water, the amorphous structure portion is first dissolved, and then the crystal structure portion is dissolved. Here, when polyvinyl alcohol is poured into hot water at a high temperature, the amorphous structure portion rapidly swells and softens to form a lump.

However, since polyvinyl alcohol having a small amount of 1,2-glycol bond has a regular structure having a molecular structure of 1,3-glycol bond, it has a strong crystal structure portion when crystallized. Generate a lot. When this strong crystal structure portion exists in the amorphous structure, it is considered that the degree of swelling and softening of the amorphous structure portion is suppressed, and the formation of agglomerates does not occur at higher temperatures.

Then, when the temperature is further raised, the amorphous structure portion is gradually dissolved, and the crystal structure portion is gradually dissolved. The larger the size of the crystal, the longer the dissolution time, but the polyvinyl alcohol having a small amount of 1,2-glycol bond has the same crystal size as the polyvinyl alcohol having a large amount of 1,2-glycol bond. It is considered that the amount of crystals increases, and the time taken to dissolve the crystals becomes faster.

Further, in the method of precipitating polyvinyl acetal by condensing an aqueous solution of polyvinyl alcohol and an aldehyde compound as in the invention of claim 3, the 1,2-glycol bond amount is 1.70 mol. % Of polyvinyl alcohol, a condensation reaction is performed at 20 ° C. or less to precipitate and precipitate polyvinyl acetal, and then an aging reaction is performed at 30 ° C. or more, a relatively large particle size (average particle size of 80 μm or more) polyvinyl acetal Is obtained. Although its mechanism of action has not been clarified, it is presumed as follows.

The size of the particles (primary particles) of the polyvinyl acetal immediately after precipitation by the condensation reaction between the aqueous solution of polyvinyl alcohol and the aldehyde compound may be either small or large in the amount of 1,2-glycol bond of polyvinyl alcohol. There is no big difference.

However, since polyvinyl alcohol having a small amount of 1,2-glycol bonds has a regular repeating unit composed of 1,3-glycol bonds, the interaction between the molecules is large and the primary particles come into contact with each other (collision). ) When you do this, you have a great deal of force trying to fit. Therefore, it is considered that the precipitated primary particles come into contact with other particles and easily grow into large particles.

Further, since the inside of the polyvinyl acetal particles thus grown into large particles is porous, it is considered that the residue such as the aldehyde compound taken into the inside is easily removed by washing.

Among the polyvinyl acetals obtained by the above production method (claims 1 to 3), polyvinyl butyral is preferably used for producing an interlayer film for laminated glass. In this case, the degree of butyralization is 60 to 70 mol%, the average degree of polymerization is 800 to 3000, and the meso-type structure of butyral ring is 75 to 8
It is preferred to use 5 mol% polyvinyl butyral. Here, the degree of butyralization and the average degree of polymerization are JIS
The meso-type structure of the butyral ring can be measured by the proton nuclear magnetic resonance spectrum method.

If the butyralization degree is less than 60 mol%, the compatibility with the plasticizer described later becomes poor and the plasticizer bleeds onto the surface of the interlayer film. On the contrary, if it exceeds 70 mol%, the heat resistance of the interlayer film becomes high. The properties and strength are reduced. On the other hand, if the average degree of polymerization is less than 800, the strength of the interlayer film is lowered, and conversely, if it exceeds 3,000, the extrusion moldability is lowered.

Further, there is a relation between the ratio of the meso-type structure of butyral ring and the creep elongation rate (80 ° C.) of the interlayer film. When the meso-type structure of polyvinyl butyral is less than 75 mol%, the creep elongation rate of the interlayer film (80 (° C.) Is more than 140%, the intermediate film becomes soft and the intermediate film is easily deformed in the process of manufacturing the laminated glass, and the handling workability is deteriorated. On the contrary, when the meso-type structure exceeds 85 mol%, the creep elongation rate (80 ° C.) of the interlayer film is lower than 40%, the interlayer film becomes hard and bubbles are generated at the interface between the interlayer film and the glass in the process of manufacturing laminated glass. Tend to remain.

Here, the creep elongation of the intermediate film (80
(° C.) means an elongation rate (%) after a lapse of 30 minutes at 80 ° C. under a load of 20 g applied to an interlayer film having a length of 40 mm, a width of 20 mm and a thickness of 0.76 mm.

The interlayer film for laminated glass of the present invention (claim 5) can be produced, for example, by the following melt-kneading extrusion method, but is not limited to the melt-kneading extrusion method.

To produce an interlayer film for laminated glass by the melt-kneading extrusion method, an appropriate amount of a plasticizer and other additives are blended with the polyvinyl butyral, and the mixture is melt-kneaded by an extruder, which is then melt-kneaded. Extrude into a film.

As the plasticizer, a plasticizer having a good compatibility with the above polyvinyl butyral, for example, triethylene glycol-di-2-ethylbutyrate, triethylene glycol-di-2-ethylheptanoate, tetraethylene glycol. -Di-2-ethylbutyrate, tetraethylene glycol-di-2-ethylheptanoate and the like are preferably used, but not limited thereto.

These plasticizers may be used alone or 2
You may use it, combining two or more types suitably. These plasticizers are contained in the range of 30 to 50 parts by weight with respect to 100 parts by weight of the polyvinyl butyral. When the content of the plasticizer is less than 30 parts by weight, the plasticizing effect is insufficient and molding becomes difficult, and the flexibility is lowered. On the contrary, when it exceeds 50 parts by weight, bleeding occurs from the interlayer film to improve transparency and adhesion. Sex decreases.

Other additives include, for example, an adhesiveness modifier made of an alkali metal salt or an alkaline earth metal salt of a carboxylic acid such as potassium acetate or magnesium acetate, a modified epoxy modified silicone oil, an ester modified silicone oil or the like. Various conventionally used additives such as an adhesive force adjusting agent made of silicone oil, an ultraviolet absorber, an antioxidant and a coloring agent are used.

In particular, the adhesive strength adjusting agent is effective in appropriately controlling the adhesive strength between the glass and the intermediate film to balance the penetration resistance of the laminated glass and the glass scattering prevention property, The interlayer film of laminated glass used as a window glass of a vehicle or an aircraft often contains the above-mentioned adhesion control agent.

Thus, the interlayer film for laminated glass of the present invention is obtained. To produce laminated glass (claim 6) using the interlayer film for laminated glass of the present invention, for example,
The following known methods are adopted. The surface of this intermediate film may be embossed by an embossing roll in the film forming step in order to improve the deaerating property during the laminating process.

First, the water content of the interlayer film for laminated glass is adjusted. The water content of this interlayer is generally between 0.4 and
It is desirable to adjust to about 0.5% by weight. Next, the above intermediate film is sandwiched between two transparent glass plates to form a sandwich body, which is placed in a vacuum rubber bag and pre-bonded at about 70 to 110 ° C. under vacuum suction, and then using an autoclave to about 120 About 10 ~ 15kg at ~ 150 ℃
It is manufactured by carrying out main bonding at a pressure of / cm ² .

As the glass plate, not only an inorganic glass plate such as a float glass but also an organic glass plate made of a transparent synthetic resin such as polycarbonate and methyl methacrylate can be used.

A polyester film in which two patterns of the above-mentioned intermediate film are used and various patterns are printed between the intermediate films,
Washi paper, punching metal sheet, heat ray-reflecting metal thin film or other film or sheet is used as a decorative interlayer or heat ray-reflecting interlayer film, and laminated glass is manufactured using such a multilayer interlayer film. You can also

From the viewpoint of surely preventing the scattering of glass fragments, in the above sandwich, the transparent inorganic glass plate or transparent organic glass on the inner side of the window glass may be replaced with a polyester film or sheet, or the window glass may be replaced. It is also possible to produce a laminated glass by further laminating a polyester film or sheet on the surface of the transparent inorganic glass plate or the transparent organic glass which is the inner side of.

The interlayer film for laminated glass using polyvinyl butyral obtained in the present invention has a meso-type structure of butyral ring, as compared with the interlayer film for laminated glass using polyvinyl butyral obtained by the conventional production method. Even if the ratio is the same, the creep elongation rate (80 ° C.) of the interlayer film is relatively small. The reason has not been fully clarified, but it can be inferred as follows.

That is, in the case of producing polyvinyl butyral by subjecting polyvinyl alcohol and butyraldehyde to a condensation reaction, polyvinyl alcohol is a chain polymer and has a small amount of 1,2-glycol bond together with 1,3-glycol bond. Since this 1,2-glycol bond does not participate in the butyralization reaction, the resulting polyvinyl butyral also has a 1,2-glycol bond site, and the smaller the amount, the more regular the hydroxyl group structure in the polyvinyl butyral is. Therefore, it is considered that the intermolecular force becomes large, and as a result, the creep elongation rate (80 ° C.) of the interlayer film becomes relatively small.

[0071]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples and comparative examples of the present invention will be described below. Example of the invention of claim 1 and comparative example Example 1 A separable flask equipped with a stirrer and a dropping funnel, polymerization degree 1700, saponification degree 99.2 mol%, 1,2-glycol bond amount 1.59. Mol% polyvinyl alcohol 2
80 parts by weight and 2850 parts by weight of water were added to dissolve the polyvinyl alcohol.

Thereafter, the temperature was maintained at 30 ° C. and hydrochloric acid (35
(Wt% aqueous solution) 21 parts by weight, and while further stirring, cool the solution temperature to 15 ° C., add 157 parts by weight of butyraldehyde to this, and confirm the precipitation of polyvinyl butyral before adding hydrochloric acid (35% by weight). Aqueous solution) (179 parts by weight) was added dropwise.

Then, the solution temperature is raised to 50 ° C. and the solution temperature is raised to 2.5.
Stirring was carried out for an hour to complete the aging reaction. The obtained precipitate was thoroughly washed with water to remove residual hydrochloric acid, and then dried with a hot air dryer at 50 ° C. for 48 hours.

In order to confirm the degree of aging, the ratio of the racemic type to the meso type of the butyral ring structure was measured by the proton nuclear magnetic resonance spectrum method ( ¹ H-NMR method) at 500 MHz. Type 82 mol%, racemic 18
It is mol%, which indicates that the structural change from the racemic type to the stable meso type is progressing. The polyvinyl butyral of the obtained white powder had a butyralization degree of 65 mol%.

Example 2 Polyvinyl alcohol having a polymerization degree of 1700, a saponification degree of 99.2 mol% and a 1,2-glycol bond amount of 1.40.
Example 1 was repeated except that mol% of polyvinyl alcohol was used.

However, in order to confirm the degree of aging, 5
When the polyvinyl butyral was appropriately extracted during the aging reaction at 0 ° C., and the ratio of meso-type to racemic-type was measured for these polyvinyl butyral, the meso-type was 82 mol% and the racemic-type was 18 mol%. The aging reaction time was 2 hours. The polyvinyl butyral of the obtained white powder had a butyralization degree of 65 mol%.

Example 3 As polyvinyl alcohol, the polymerization degree was 1700, the saponification degree was 99.2 mol%, and the 1,2-glycol bond amount was 1.30.
Example 1 was repeated except that mol% of polyvinyl alcohol was used.

However, in order to confirm the degree of aging, 5
When the polyvinyl butyral was appropriately extracted during the aging reaction at 0 ° C., and the ratio of meso-type to racemic-type was measured for these polyvinyl butyral, the meso-type was 82 mol% and the racemic-type was 18 mol%. The aging reaction time was 1.5 hours. The polyvinyl butyral of the obtained white powder had a butyralization degree of 65 mol%.

Example 4 The procedure of Example 2 was repeated, except that 179 parts by weight of hydrochloric acid (35% by weight aqueous solution) added dropwise was changed to 157 parts by weight. In this case, the aging reaction time until the meso type was 82 mol% and the racemic type was 18 mol% was 2.5 hours. The polyvinyl butyral of the obtained white powder had a butyralization degree of 65 mol%. Met.

Example 5 Except that the temperature of the aging reaction, 50 ° C., was changed to 40 ° C.,
Performed in the same manner as in Example 2. In this case, the aging reaction time until the meso type was 82 mol% and the racemic type was 18 mol% was 2.5 hours. The polyvinyl butyral of the obtained white powder had a butyralization degree of 65 mol%.

Example 6 In a reactor equipped with a stirrer and a reflux condenser, 2850 parts by weight of isopropyl alcohol and 9 parts by weight of hydrochloric acid (35% by weight aqueous solution)
With stirring 7 parts by weight, the polymerization degree is 1700, the saponification degree is 98.0 mol%, and the 1,2-glycol bond amount is 1.5.
280 parts by weight of 9 mol% polyvinyl alcohol was added, and 157 parts by weight of butyraldehyde was added.

Then, the solution temperature was raised to 60 ° C. and the mixture was stirred for 3 hours to carry out a condensation reaction and an aging reaction. Water was added to the obtained polyvinyl butyral solution to precipitate polyvinyl butyral, which was washed with warm water to remove residual hydrochloric acid, and then dried with a hot air dryer at 50 ° C. for 48 hours.

In order to confirm the degree of aging, the ratio of the racemic type of the butyral ring structure to the meso type was measured by the proton nuclear magnetic resonance skull method ( ¹ H-NMR method) at 500 MHz. It is 83 mol% and the racemic type is 17 mol%, which shows that the structural change from the racemic type to the stable meso type is progressing. The polyvinyl butyral of the obtained white powder had a butyralization degree of 65 mol%.

Example 7 As polyvinyl alcohol, the degree of polymerization was 1700, the degree of saponification was 98.0 mol%, and the amount of 1,2-glycol bond was 1.40.
Example 6 was performed in the same manner as in Example 6 except that the condensation reaction and the aging reaction temperature were changed from 60 ° C to 50 ° C by using mol% of polyvinyl alcohol.

However, in order to confirm the degree of aging, 5
When the polyvinyl butyral was appropriately extracted during the aging reaction at 0 ° C., and the ratio of meso-type to racemic-type was measured for these polyvinyl butyral, the meso-type was 83 mol% and the racemic-type was 17% mol. The aging reaction time was 3 hours. The polyvinyl butyral of the obtained white powder had a butyralization degree of 65 mol%.

Example 8 A charged amount of hydrochloric acid (35% by weight aqueous solution) of 21 parts by weight was adjusted to 67
The same procedure as in Example 6 was carried out except that the weight part was changed.

However, in order to confirm the degree of aging, 6
When the polyvinyl butyral was appropriately extracted during the aging reaction at 0 ° C., and the ratio of meso-type to racemic-type was measured for these polyvinyl butyral, the meso-type was 83 mol% and the racemic-type was 17 mol%. The aging reaction time was 3 hours. The polyvinyl butyral of the obtained white powder had a butyralization degree of 65 mol%.

Comparative Example 1 Polyvinyl alcohol having a degree of polymerization of 1700, a degree of saponification of 99.2 mol% and a 1,2-glycol bond amount of 1.74.
Example 1 was repeated except that mol% of polyvinyl alcohol was used.

However, in order to confirm the degree of aging, 5
When the polyvinyl butyral was appropriately extracted during the aging reaction at 0 ° C., and the ratio of meso-type to racemic-type was measured for these polyvinyl butyral, the meso-type was 82 mol% and the racemic-type was 18 mol%. The aging reaction time was 4 hours, which was longer than that in Example 1. The degree of butyralization of the obtained white powder polyvinyl butyral is 6
It was 5 mol%.

Comparative Example 2 Polyvinyl alcohol having a polymerization degree of 1700, a saponification degree of 98.0 mol% and a 1,2-glycol bond amount of 1.74.
Example 6 was repeated except that mol% of polyvinyl alcohol was used.

However, in order to confirm the degree of aging, 6
When the polyvinyl butyral was appropriately extracted during the aging reaction at 0 ° C., and the ratio of meso-type to racemic-type was measured for these polyvinyl butyral, the meso-type was 83 mol% and the racemic-type was 17 mol%. The aging reaction time was 6 hours, which was longer than that in Example 6. The degree of butyralization of the obtained white powder polyvinyl butyral is 6
It was 5 mol%. The results of Examples 1 to 8 and Comparative Examples 1 and 2 are summarized in Table 1.

[0092]

[Table 1]

Example of the Invention of Claim 2 and Comparative Example Example 9 In a separable flask equipped with a stirrer and a dropping funnel, a polymerization degree of 1700, a saponification degree of 99.2 mol% and a 1,2-glycol bond amount. 1.59 mol% polyvinyl alcohol 2
80 parts by weight were added to 2850 parts by weight of warm water at 50 ° C. At this time, no lump of polyvinyl alcohol was generated.

Thereafter, the temperature was raised to 95 ° C. at a rate of 0.5 ° C./minute, and the mixture was stirred at 95 ° C. for 1 hour to dissolve polyvinyl alcohol. At this point, when the entire aqueous solution was filtered through a 20-mesh wire net, it was confirmed that no insoluble matter remained on the wire net and that the polyvinyl alcohol was completely dissolved.

Thereafter, the temperature was kept at 30 ° C. and hydrochloric acid (35
(Wt% aqueous solution) 21 parts by weight, and while further stirring, cool the solution temperature to 15 ° C., add 157 parts by weight of butyraldehyde to this, and confirm the precipitation of polyvinyl butyral before adding hydrochloric acid (35% by weight). Aqueous solution) (179 parts by weight) was added dropwise.

Next, the solution temperature was raised to 50 ° C. and stirring was carried out for 2 hours and a half to complete the aging reaction. The obtained precipitate was thoroughly washed with water to remove residual hydrochloric acid, and then dried with a hot air dryer at 50 ° C. for 48 hours.

The polyvinyl butyral of the obtained white powder had a butyralization degree of 65 mol%. In the above method, the time required to raise the temperature from 50 ° C to 95 ° C is 90
Minutes.

Example 10 As polyvinyl alcohol, the polymerization degree was 1700, the saponification degree was 99.2 mol%, and the 1,2-glycol bond amount was 1.40.
Example 9 was performed in the same manner as in Example 9 except that mol% of polyvinyl alcohol was used and the water temperature at the time of adding polyvinyl alcohol was changed to 55 ° C.

In the above method, no lump of polyvinyl alcohol was generated when polyvinyl butyral was charged. Also, by filtering the polyvinyl alcohol aqueous solution,
It was confirmed that the polyvinyl alcohol was completely dissolved. The time required to raise the temperature from 55 ° C to 95 ° C was 80 minutes. The polyvinyl butyral of the obtained white powder had a butyralization degree of 65 mol%.

Example 11 As polyvinyl alcohol, the degree of polymerization was 1700, the degree of saponification was 99.2 mol%, and the amount of 1,2-glycol bond was 1.30.
The same procedure as in Example 9 was performed except that mol% of polyvinyl alcohol was used and the water temperature at the time of charging polyvinyl alcohol was changed to 60 ° C. The polyvinyl butyral of the obtained white powder had a butyralization degree of 65 mol%.

In the above method, no lump of polyvinyl alcohol was generated when polyvinyl butyral was charged. Also, by filtering the polyvinyl alcohol aqueous solution,
It was confirmed that the polyvinyl alcohol was completely dissolved. The time required to raise the temperature from 60 ° C. to 95 ° C. is 70 minutes. The polyvinyl butyral of the obtained white powder had a butyralization degree of 65 mol%.

Comparative Example 3 A polyvinyl alcohol having a polymerization degree of 1700, a saponification degree of 99.2 mol% and a 1,2-glycol bond amount of 1.74 mol% was placed in a separable flask equipped with a stirrer and a dropping funnel. 280 parts by weight of alcohol was added to 2850 parts by weight of warm water at 60 ° C. At this time, a lump of polyvinyl alcohol was instantly generated.

Then, the temperature was raised to 95 ° C. at a rate of 0.5 ° C./min, and the mixture was stirred at 95 ° C. for 1 hour to dissolve polyvinyl alcohol. At this point, when the entire aqueous solution was filtered through a 20-mesh wire net, 70 parts by weight of insoluble matter remained on the wire net, so the subsequent synthesis operation was stopped. The time required to raise the temperature from 60 ° C. to 95 ° C. is 70 minutes.

Comparative Example 4 As polyvinyl alcohol, polymerization degree 1700, saponification degree 99.2 mol%, 1,2-glycol bond amount 1.74.
Example 9 was repeated except that mol% of polyvinyl alcohol was used.

In this case, polyvinyl alcohol is added at 50 ° C.
Immediately when it was added to the warm water, lumps of polyvinyl alcohol were generated. However, at a rate of 0.5 ° C / min, 95
After the temperature was raised to ℃, the mixture was stirred at 95 ℃ for 1 hour to dissolve the polyvinyl alcohol, and then the entire aqueous solution was filtered through a wire mesh of 20 mesh, no insoluble matter remained on the wire mesh. I continued.

In the above method, the time required for raising the temperature from 50 ° C. to 95 ° C. is 90 minutes as in Example 9. However, the butyralization degree of polyvinyl butyral of the obtained white powder was 62 mol%, and the butyralization degree was lower than that of Example 9.

Comparative Example 5 As polyvinyl alcohol, the degree of polymerization was 1700, the degree of saponification was 99.2 mol%, and the amount of 1,2-glycol bond was 1.74.
Example 9 was performed in the same manner as in Example 9 except that mol% of polyvinyl alcohol was used and the water temperature at the time of charging polyvinyl alcohol was changed to 40 ° C.

In this case, polyvinyl alcohol is added at 40 ° C.
No polyvinyl alcohol agglomerates were generated when the mixture was poured into warm water. Also, 95 ° C at a rate of 0.5 ° C / min.
The mixture was heated up to 95 ° C. and stirred at 95 ° C. for 1 hour to dissolve the polyvinyl alcohol, and then the entire aqueous solution was filtered through a 20-mesh wire net. No insoluble matter remained on the wire net, and the polyvinyl alcohol was completely dissolved. Was confirmed.

The polyvinyl butyral of the obtained white powder had a butyralization degree of 65 mol%. But 40
The temperature rising time from ° C to 95 ° C was 110 minutes, which was longer than that in Example 9.

Comparative Example 6 Polyvinyl alcohol having a polymerization degree of 1700, a saponification degree of 99.2 mol% and a 1,2-glycol bond amount of 2.10
Example 9 was repeated except that mol% of polyvinyl alcohol was used.

In this case, polyvinyl alcohol is added at 50 ° C.
Immediately when it was added to the warm water, lumps of polyvinyl alcohol were generated. However, at a rate of 0.5 ° C / min, 95
After the temperature was raised to ℃, the mixture was stirred at 95 ℃ for 1 hour to dissolve the polyvinyl alcohol, and then the entire aqueous solution was filtered through a wire mesh of 20 mesh, no insoluble matter remained on the wire mesh. I continued.

The temperature rising time from 40 ° C. to 95 ° C. is 90 minutes as in Example 9. However, the degree of butyralization of the obtained white powder polyvinyl butyral is 60 mol%.
And the degree of butyralization was lower than in Example 9.
The results of Examples 9 to 11 and Comparative Examples 3 to 6 are summarized in Table 2.

[0113]

[Table 2]

Example of the Invention of Claim 3 and Comparative Example Example 12 A separable flask equipped with a stirrer and a dropping funnel had a polymerization degree of 1700, a saponification degree of 99.2 mol% and a 1,2-glycol bond amount. 1.59 mol% polyvinyl alcohol 2
80 parts by weight and 2850 parts by weight of water were added to dissolve the polyvinyl alcohol.

Thereafter, the temperature was maintained at 30 ° C. and hydrochloric acid (35
(Wt% aqueous solution) 21 parts by weight, and while further stirring, cool the solution temperature to 15 ° C., add 157 parts by weight of butyraldehyde to this, and confirm the precipitation of polyvinyl butyral before adding hydrochloric acid (35% by weight). Aqueous solution) (179 parts by weight) was added dropwise.

Then, the solution temperature was raised to 50 ° C. and the solution temperature was raised to 2.5.
Stirring was carried out for an hour to complete the aging reaction. The obtained precipitate was thoroughly washed with water to remove residual hydrochloric acid, and then dried with a hot air dryer at 50 ° C. for 48 hours.

The butyralization degree of the obtained white powder polyvinyl butyral was 65 mol%. When the particle size of this polyvinyl butyral was measured with a particle size analyzer (Tubtec particle size analyzer manufactured by Swanya Transtech), the average particle size was 110 μm.

The polyvinyl butyral particles were dissolved in dimethylformamide, and the amount of residual butyraldehyde in the polyvinyl butyral particles was measured by gas chromatography. No residual butyraldehyde was detected.

Example 13 As polyvinyl alcohol, polymerization degree 1700, saponification degree 99.2 mol%, 1,2-glycol bond amount 1.40.
Example 12 was repeated except that mol% of polyvinyl alcohol was used.

The polyvinyl butyral of the obtained white powder had a butyralization degree of 65 mol%. The average particle size of the polyvinyl butyral particles was 125 μm. Further, residual butyraldehyde in the polyvinyl butyral particles was not detected.

Example 14 Polyvinyl alcohol having a degree of polymerization of 1700, a degree of saponification of 99.2 mol% and a 1,2-glycol bond amount of 1.30.
Example 12 was repeated except that mol% of polyvinyl alcohol was used.

The polyvinyl butyral of the obtained white powder had a butyralization degree of 65 mol%. The average particle size of the polyvinyl butyral particles was 125 μm. Further, residual butyraldehyde in the polyvinyl butyral particles was not detected.

Comparative Example 7 Polyvinyl alcohol having a degree of polymerization of 1700, a degree of saponification of 99.2 mol% and a 1,2-glycol bond amount of 1.74.
Example 12 was repeated except that mol% of polyvinyl alcohol was used.

The polyvinyl butyral of the obtained white powder had a butyralization degree of 65 mol%. Further, residual butyraldehyde in the polyvinyl butyral particles was not detected. However, the average particle diameter of the polyvinyl butyral particles was 70 μm, which was smaller than that of Example 12.

Comparative Example 8 Polyvinyl alcohol having a polymerization degree of 1700, a saponification degree of 99.2 mol% and a 1,2-glycol bond amount of 1.74.
Aging reaction temperature 5 using mol% of polyvinyl alcohol
Example 12 was repeated except that 0 was changed to 60 ° C.

The polyvinyl butyral of the obtained white powder had a butyralization degree of 65 mol%. Further, residual butyraldehyde in the polyvinyl butyral particles was not detected. However, the average particle size of the polyvinyl butyral particles was 75 μm, which was smaller than that of Example 12.

Comparative Example 9 Polyvinyl alcohol having a polymerization degree of 1700, a saponification degree of 99.2 mol% and a 1,2-glycol bond amount of 1.74.
Example 12 was carried out in the same manner as in Example 12, except that mol% of polyvinyl alcohol was used and the aging reaction time was changed from 2.5 hours to 3.5 hours.

The polyvinyl butyral of the obtained white powder had a butyralization degree of 65 mol%. Further, residual butyraldehyde in the polyvinyl butyral particles was not detected. However, the average particle size of the polyvinyl butyral particles was 75 μm, which was smaller than that of Example 12.

Comparative Example 10 As polyvinyl alcohol, the degree of polymerization was 1700, the degree of saponification was 99.2 mol%, and the amount of 1,2-glycol bond was 1.74.
Precipitation precipitation temperature 1 using mol% of polyvinyl alcohol
The same procedure as in Example 12 was repeated except that 5 ° C was changed to 25 ° C.

The degree of butyralization of the obtained white powder polyvinyl butyral was 65 mol%. The average particle size of the polyvinyl butyral particles is 100 μm,
It was relatively large. However, residual butyraldehyde in the polyvinyl butyral particles was detected, and the amount was 100%.
It was ppm.

Comparative Example 11 Polyvinyl alcohol having a degree of polymerization of 1700, a degree of saponification of 99.2 mol% and a 1,2-glycol bond amount of 2.10
Example 12 was repeated except that mol% of polyvinyl alcohol was used.

The butyralization degree of the obtained white powder polyvinyl butyral was 65 mol%. Further, residual butyraldehyde in the polyvinyl butyral particles was not detected. However, the average particle diameter of the polyvinyl butyral particles was 55 μm, which was smaller than that of Example 12.

Comparative Example 12 Example 12 was repeated except that the aging reaction temperature of 50 ° C. was changed to 20 ° C. and the aging reaction time of 2.5 hours was 6.0 hours.
I went the same way.

The polyvinyl butyral of the obtained white powder had a butyralization degree of 65 mol%. Further, residual butyraldehyde in the polyvinyl butyral particles was not detected. However, the average particle diameter of the polyvinyl butyral particles was 50 μm, which was smaller than that of Example 12. Examples 12-14 and Comparative Examples 7-12
The results are summarized in Table 3.

[0135]

[Table 3]

Embodiments relating to the inventions of claims 5 and 6 and
Comparative Example 15 Production of laminated glass interlayer 100 parts by weight of polyvinyl butyral obtained in Example 1, 40 parts by weight of triethylene glycol-di-2-ethylbutyrate, 0.05 parts by weight of magnesium acetate and modified silicone oil (F328S manufactured by Shin-Etsu Chemical Co., Ltd.) 0.05 part by weight is mixed by a raider machine, and the mixture is extruded into a sheet at 180 to 220 ° C. using an extruder.
An interlayer film for laminated glass having a thickness of 0.76 mm was manufactured.

In order to measure the creep elongation rate (80 ° C.) of this interlayer film, test pieces were prepared by cutting into strips having a length of 80 mm and a width of 20 mm, and marked lines were attached to the positions 20 mm from both ends. Then, this was hung in a hot air dryer at 80 ° C. in the longitudinal direction, a 20 g weight was hung at the lower end thereof, and the creep elongation rate between both marked lines after 30 minutes was measured,
The creep elongation rate was 100%. In addition, this creep elongation rate is (the length between both marked lines after 30 minutes -40 m
m) / 40 mm × 100 (%).

Manufacture of Laminated Glass The interlayer film for laminated glass having a water content of 0.
Adjust to 4 to 0.5% by weight, and use two transparent float glass plates (length 300 mm x width 300 mm x 3 mm).
Sandwiched between them to make a sandwich, put this in a vacuum rubber bag and pre-bond at 100 ° C while vacuuming at 10 torr vacuum for 20 minutes, then put in autoclave and put at 145 ° C, 13 kg / cm ² The main adhesion was performed under the pressure of 1 to produce a transparent laminated glass.

Example 16 Polyvinyl alcohol having a polymerization degree of 1700, a saponification degree of 99.2 mol% and a 1,2-glycol bond amount of 1.40.
2.5% at 50 ° C with mol% of polyvinyl alcohol
The same procedure as in Example 1 was carried out except that the aging reaction was carried out for 2 hours to obtain a polyvinyl butyral white powder having a butyralization degree of 65 mol%, a butyral ring meso-type 82 mol%, and a racemo-type 18 mol%. It was

An interlayer film for laminated glass and a laminated glass were produced in the same manner as in Example 15 except that this polyvinyl butyral was used. The creep elongation rate (80 ° C.) of the interlayer film for laminated glass was 90%.

Example 17 As polyvinyl alcohol, polymerization degree 1700, saponification degree 99.2 mol%, 1,2-glycol bond amount 1.30
2.5% at 50 ° C with mol% of polyvinyl alcohol
Example 1 except that the aging reaction time was 1.5 hours.
In the same manner as described above, white butyral polyvinyl butyral having a butyralization degree of 65 mol%, a butyral ring meso-type 82 mol% and a racemo-type 18 mol% was obtained.

An interlayer film for laminated glass and a laminated glass were produced in the same manner as in Example 15 except that this polyvinyl butyral was used. The creep elongation rate (80 ° C.) of the interlayer film for laminated glass was 80%.

Example 18 Polyvinyl alcohol having a degree of polymerization of 1700, a degree of saponification of 99.2 mol% and a 1,2-glycol bond amount of 1.59.
2.5% at 50 ° C with mol% of polyvinyl alcohol
The same procedure as in Example 1 was carried out except that the aging reaction was carried out for 3 hours to obtain a polyvinyl butyral white powder having a butyralation degree of 65 mol%, a butyral ring meso-type 83 mol%, and a racemo-type 17 mol%. It was

An interlayer film for laminated glass and a laminated glass were produced in the same manner as in Example 15 except that this polyvinyl butyral was used. The creep elongation rate (80 ° C.) of the interlayer film for laminated glass was 90%.

Example 19 Polyvinyl alcohol having a polymerization degree of 1700, a saponification degree of 99.2 mol% and a 1,2-glycol bond amount of 1.59.
2.5% at 50 ° C with mol% of polyvinyl alcohol
Example 1 except that the aging reaction time was 1.5 hours.
In the same manner as described above, white butyral polyvinyl butyral having a butyralization degree of 65 mol%, a meso-type butyral ring of 80 mol% and a racemo type of 20 mol% was obtained.

An interlayer film for laminated glass and a laminated glass were produced in the same manner as in Example 15 except that this polyvinyl butyral was used. The creep elongation rate (80 ° C.) of the interlayer film for laminated glass was 110%.

Example 20 Polyvinyl alcohol having a polymerization degree of 1700, a saponification degree of 99.2 mol% and a 1,2-glycol bond amount of 1.59.
2.5% at 50 ° C with mol% of polyvinyl alcohol
A white powdery polyvinyl butyral having a butyralization degree of 65 mol%, a butyral ring meso-type 77 mol%, and a racemo-type 23 mol% was obtained in the same manner as in Example 1 except that the aging reaction for 1 hour was performed. It was

An interlayer film for laminated glass and a laminated glass were produced in the same manner as in Example 15 except that this polyvinyl butyral was used. The creep elongation rate (80 ° C.) of the interlayer film for laminated glass was 130%.

Comparative Example 13 Polyvinyl alcohol having a degree of polymerization of 1700, a degree of saponification of 99.2 mol% and a 1,2-glycol bond amount of 1.74.
2.5% at 50 ° C with mol% of polyvinyl alcohol
A white powdery polyvinyl butyral having a butyralization degree of 65 mol%, a butyral ring meso-type 82 mol% and a racemo-type 18 mol% is obtained in the same manner as in Example 1 except that the aging reaction is carried out for 4 hours. It was

An interlayer film for laminated glass and a laminated glass were produced in the same manner as in Example 15 except that this polyvinyl butyral was used. The creep elongation rate (80 ° C.) of the interlayer film for laminated glass was 110%.

Comparative Example 14 Polyvinyl alcohol having a degree of polymerization of 1700, a degree of saponification of 99.2 mol% and a 1,2-glycol bond amount of 1.74.
2.5% at 50 ° C with mol% of polyvinyl alcohol
A white powdery polyvinyl butyral having a butyralization degree of 65 mol%, a butyral ring meso type of 83 mol%, and a racemo type of 17 mol% was obtained in the same manner as in Example 1 except that the aging reaction was carried out for 6 hours. It was

An interlayer film for laminated glass and a laminated glass were produced in the same manner as in Example 15 except that this polyvinyl butyral was used. The creep elongation rate (80 ° C.) of the interlayer film for laminated glass was 100%.

Comparative Example 15 Polyvinyl alcohol having a polymerization degree of 1700, a saponification degree of 99.2 mol% and a 1,2-glycol bond amount of 1.74.
2.5% at 50 ° C with mol% of polyvinyl alcohol
A white powder of polyvinyl butyral having a butyralization degree of 65 mol%, a meso type of butyral ring of 85 mol%, and a racemo type of 15 mol% was obtained in the same manner as in Example 1 except that the aging reaction for 8 hours was performed. It was

An interlayer film for laminated glass and a laminated glass were produced in the same manner as in Example 15 except that this polyvinyl butyral was used. The creep elongation rate (80 ° C.) of the interlayer film for laminated glass was 80%. The results of Examples 15 to 20 and Comparative Examples 13 to 15 are summarized in Table 4.

[0155]

[Table 4]

[0156]

As described above, the invention of claim 1 is a method for producing a polyvinyl acetal by condensing polyvinyl alcohol and an aldehyde compound.
Polyvinyl alcohol having a glycol bond content of 1.70 mol% or less is used, whereby the time of the aging reaction can be shortened and the production time of the polyvinyl acetal can be shortened.

Further, the invention of claim 2 is a method for producing a polyvinyl acetal by condensing an aqueous polyvinyl alcohol solution and an aldehyde compound (precipitation method),
The polyvinyl alcohol aqueous solution is obtained by using polyvinyl alcohol having a 1,2-glycol bond content of 1.70 mol% or less, and pouring the polyvinyl alcohol into warm water of 45 to 65 ° C. and then dissolving the polyvinyl alcohol at 90 ° C. or higher. Therefore, the preparation time of the polyvinyl alcohol aqueous solution can be shortened and the manufacturing time of the polyvinyl acetal can be shortened.

Further, the invention of claim 3 is a method for producing a polyvinyl acetal by condensing an aqueous solution of polyvinyl alcohol and an aldehyde compound (precipitation method),
A polyvinyl alcohol having a 1,2-glycol bond content of 1.70 mol% or less is used to carry out an aging reaction at 20 ° C. or higher, whereby a polyvinyl acetal having a relatively large particle size and an average particle size of preferably 80 μm or more is obtained. It can be manufactured.

Thus, the polyvinyl acetal having a relatively large particle size and an average particle size of preferably 80 μm or more is
Fine powder does not fly up during handling, and the bite into the screw does not deteriorate during extrusion molding.
Particularly, it is suitable as a raw material for producing a sheet such as an interlayer film for laminated glass by extrusion molding.

In the inventions of claims 2 and 3,
Since the above-mentioned specific polyvinyl alcohol is used as in the case of the invention of claim 1, it goes without saying that the same effect as that of the invention of claim 1 can be obtained in that the time of the aging reaction can be shortened.

Further, in the invention of claim 3, in claim 2
As in the invention of 4,
If the polyvinyl alcohol aqueous solution is obtained by pouring the mixture into warm water of 5 to 65 ° C. and then dissolving it at 90 ° C. or higher, the effect of shortening the preparation time of the polyvinyl alcohol aqueous solution can be obtained like the invention of claim 2. Needless to say.

Further, since the polyvinyl acetal of the invention of claim 4 is obtained by the production method of any one of claims 1 to 3, the cost is lower than that of the conventional polyvinyl acetal.

Further, in the interlayer film for laminated glass according to the invention of claim 5, even when the proportion of meso-type structure of butyral ring of polyvinyl butyral used (the same degree of aging) is the same as that of conventional polyvinyl butyral, the creep Growth rate (8
(0 ° C.) is relatively small, and the workability of handling the interlayer film in the manufacturing process of laminated glass is excellent, and the cost is lower than that of the conventional interlayer film.

Furthermore, since the laminated glass of the invention of claim 6 uses the above-mentioned intermediate film, the cost is lower than that of the conventional intermediate film.

Claims (6)

[Claims] 1. A method for producing a polyvinyl acetal by condensing polyvinyl alcohol and an aldehyde compound, wherein polyvinyl alcohol having a 1,2-glycol bond content of 1.70 mol% or less is used. Production method. 2. A method for producing a polyvinyl acetal by condensing an aqueous polyvinyl alcohol solution and an aldehyde compound (precipitation method), wherein polyvinyl alcohol having a 1,2-glycol bond content of 1.70 mol% or less is used. A method for producing a polyvinyl acetal, which comprises pouring alcohol into warm water of 45 to 65 ° C. and then dissolving it at 90 ° C. or higher to obtain the polyvinyl alcohol aqueous solution. 3. A method for producing a polyvinyl acetal by condensing an aqueous solution of polyvinyl alcohol and an aldehyde compound (precipitation method), wherein polyvinyl alcohol having a 1,2-glycol bond content of 1.70 mol% or less is used, and the temperature is 20 ° C. A method for producing a polyvinyl acetal, which comprises subjecting a polyvinyl acetal to precipitation by performing a condensation reaction below, and then performing an aging reaction at 30 ° C. or higher. 4. A polyvinyl acetal obtained by the manufacturing method according to claim 1. 5. An interlayer film for laminated glass using polyvinyl butyral among the polyvinyl acetals according to claim 4. 6. A laminated glass using the interlayer film for laminated glass according to claim 5.