JPH0559117A - Production of polyvinyl acetal resin - Google Patents

Abstract

PURPOSE:To obtain the subject resin having high fluidity in hot-pressing with glass plates and useful for a safety glass interlayer, etc., by preliminarily reacting an aqueous solution of PVA with an aldehyde under circulation in a loop reactor under specific conditions and aging the reaction product in a tank reactor. CONSTITUTION:The objective polyvinyl acetal resin effective for giving a safety glass interlayer having improved hot-fluidity, autohesion property and rigidity and free from blocking of the films with each other is produced by dissolving a polyvinyl alcohol in water in a polyvinyl alcohol dissolution tank 1, transferring the obtained aqueous solution to a loop reactor 10, mixing with an aldehyde such as butyraldehyde supplied from an aldehyde tank 3, adjusting the pH of the reaction liquid to 1.0-1.45 with an acid catalyst such as hydrochloric acid, adjusting the charged amount of the aldehyde to a level larger than the theoretical level necessary to attain the target acetalization degree by 3-15%, preliminarily reacting the components at 50-95 deg.C at an average residence time of 4-8min while circulating through the loop reactor 10 and finally aging the reaction product in a tank reactor 2 under stirring at 60-100 deg.C for 3-6hr.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyvinyl acetal resin suitable for use as an interlayer film for laminated glass.

[0002]

2. Description of the Related Art Polyvinyl acetal resins such as polyvinyl butyral are widely used as raw materials for interlayer films for laminated glass.

Such a polyvinyl acetal resin is
Generally, it is produced by a precipitation method using an aqueous medium. The reason is that the precipitation method using this aqueous medium is industrially advantageous because it does not require recovery of an expensive solvent unlike the solution method.

As a precipitation method using an aqueous medium, US Pat.
No. 2,720,501 discloses that an aqueous polyvinyl alcohol solution and an aldehyde are circulated in a loop reactor while
A method for producing a polyvinyl acetal resin such as polyvinyl butyral is disclosed by preliminarily reacting at -95 ° C and then aging reaction at 60-100 ° C while stirring in a tank reactor.

According to this method, the reaction solution of the polyvinyl alcohol aqueous solution and the aldehyde circulates in the loop reactor at a high speed, so that the particles produced by the reaction are prevented from agglomerating, and the temperature is raised to 50 to 100 ° C. Since the reaction is carried out at 1, the gelation of polyvinyl alcohol is prevented during the acetalization reaction, and there is an advantage that a high-quality polyvinyl acetal resin having good heat fluidity can be obtained.

[0006]

However, a polyvinyl butyral resin produced according to this method is used, and an appropriate amount of a conventional plasticizer such as triethylene glycol di-2-ethylbutyrate is added to the polyvinyl butyral resin. The interlayer film for glass is too strong in self-adhesive force to be wound into a roll and stored, or cut into glass dimensions and laminated and stored in the manufacturing process of laminated glass, and the films will work closely together. There is a problem of poor sex.

Further, when the interlayer film is cut along the glass in the process of manufacturing a laminated glass, there is a problem that the rigidity of the film is too small and the interlayer film cannot be cut smoothly.

The present invention is intended to solve such a problem, and its object is to improve the self-adhesiveness and rigidity of the interlayer film for laminated glass as well as the self-adhesive force and the rigidity of the interlayer film for laminated glass. Another object of the present invention is to provide a method for producing a polyvinyl acetal resin capable of smoothly cutting a film.

[0009]

In order to achieve the above-mentioned object, the inventor has made various studies on the above-mentioned prior art. As a result, the polyvinyl alcohol aqueous solution and the aldehyde are preliminarily reacted at 50 to 95 ° C while circulating in the loop reactor, and then 60 to 10 while being stirred in the tank reactor.
In the method for producing a polyvinyl acetal resin by performing an aging reaction at 0 ° C., the pH of the reaction solution is adjusted to 1.0 to 1.45 with an acid catalyst, and the amount of aldehyde charged is the theoretical amount of 3 to obtain the desired degree of acetalization. -15% increase, the average residence time of the reaction liquid circulating in the loop reactor is 4 to 8 minutes, and the aging reaction time in the tank reactor is 3 to 6 hours. It was found that the purpose was achieved.

The present invention will be described in detail below with reference to the reactor shown in FIG. FIG. 1 is a schematic explanatory view showing an example of a reaction apparatus used in the method for producing a polyvinyl acetal resin of the present invention. This reactor is equipped with a polyvinyl alcohol dissolution tank 1, an aldehyde tank 3, a loop reactor 10, and a tank reactor 2.

The polyvinyl alcohol dissolving tank 1 and the loop reactor 10 are connected by a supply pipe 4, and the aldehyde tank 3 and the loop reactor 10 are connected by a supply pipe 6. The loop reactor 10 and the tank reactor 2 are connected by a transfer pipe 5. 17 is an extraction valve.

The loop reactor 10 is provided with a circulation pump 7, a pressure gauge 8 and a flowmeter 9, and the supply pipe 4,
6 are provided with supply pumps 14 and 16, respectively.
Further, the tank reactor 2 is provided with a reflux condenser (not shown) in order to prevent unreacted aldehyde from flowing out of the system.

In such a reactor, an aqueous solution of polyvinyl alcohol is prepared in the polyvinyl alcohol dissolving tank 1. As the polyvinyl alcohol, polyvinyl alcohol having an average degree of polymerization of 200 to 2600 and a degree of saponification of 90 to 100% is generally used. And generally 5-12
It is an aqueous solution of wt%. Alternatively, the viscosity measured with a 4% aqueous solution at 20 ° C. is generally adjusted to be 4-60 centipoise.

An acid catalyst is added to the aqueous solution of polyvinyl alcohol. Acid catalysts include hydrochloric acid, formic acid, phosphoric acid,
One or a mixture of two or more of sulfuric acid, paratoluenesulfonic acid, etc. is used. These acid catalysts are used in the p
An appropriate amount is added so that H becomes 1.0 to 1.45. If the pH of the reaction solution is lower than 1.0, the problem of corrosion of the reactor will occur,
On the contrary, when the pH is higher than 1.45, the reaction rate becomes slow.

Aldehyde or an aqueous solution thereof is prepared in the aldehyde tank 3. As the aldehyde, generally, a single aldehyde of aliphatic aldehyde such as formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde or a mixed aldehyde of two or more kinds is used. When producing a resin for a laminated glass interlayer film, butyraldehyde is generally used. The aldehydes include aldehydes such as paraformaldehyde and paraacetaldehyde that can be converted into the above aldehydes.

First, an aqueous solution of polyvinyl alcohol containing an appropriate amount of an acid catalyst is supplied to the loop reactor 10 by the supply pump 4 at a constant rate, and the aldehyde or its aqueous solution is supplied by the supply pump 6 to the loop reactor 10. Is supplied at a fixed rate. The charged amount (supply amount) of the aldehyde is supplied in excess of 3 to 15% of the theoretical amount necessary to obtain the desired degree of acetalization. If the amount of aldehyde charged is less than this, the compatibility of the resulting resin will be poor, and if it is more than this, the desired rigidity cannot be obtained when the resulting resin is used as an interlayer film.

When producing a polyvinyl butyral resin for a laminated glass interlayer film, the target butyralization degree is 65 to
It is particularly preferable to set it in the range of 67 mol%. If the butyralization degree is less than 65%, not only the melt viscosity of the film increases but also the compatibility with the plasticizer deteriorates. On the contrary, when the butyralization degree exceeds 67%, the melt viscosity of the film becomes low. In this case, the theoretical amount of butyraldehyde is 53.2 to 54.8 parts by weight based on 100 parts by weight of polyvinyl alcohol, and the present invention uses 3 to 15% of that butyraldehyde.

The aqueous solution of polyvinyl alcohol and the aldehyde or its aqueous solution are mixed through the confluence of the loop reactor 10, and the mixed reaction liquid is circulated in the loop reactor 10 by the circulation pump 7. Preliminary reaction between polyvinyl alcohol and aldehyde is carried out in the loop reactor 10. The preliminary reaction temperature is 50 to 95 ° C. At this time, the inner wall of the loop reactor 10 is made of glass, and the flow rate of the reaction liquid circulating in the loop reactor 11 is generally 1.5 / sec or more, preferably 5 m / sec or more.

This is because if the inner wall of the loop reactor 10 is made of glass, it becomes difficult for the resin to adhere and corrosion by the acid catalyst is prevented. Further, when the flow velocity of the reaction liquid is high, the reaction liquid forms a strong turbulent flow, which prevents the resin particles from aggregating and prevents the scale from adhering to the inner wall of the apparatus. The loop reactor 10 may be used not only as one unit but also as two or more units connected in series.

The average residence time of the reaction liquid circulating in the loop reactor 10 is 4 to 8 minutes. Here, the average residence time of the fluid is represented by a value obtained by dividing the volume of the loop reactor 10 by the volume of the reaction liquid supplied thereto. If this average residence time is less than 4 minutes, the proportion of acetalization of the preliminary reaction liquid introduced into the tank-shaped reactor 2 is too low, and particles are coalesced in the tank-shaped reactor 2 to form a good resin. I can't get it. Conversely, if the average residence time exceeds 8 minutes, the tank reactor 2
The rate of acetalization of the pre-reaction liquid added to the reactor is too high, and a long-term aging reaction is required to obtain a resin having a preferred hydroxyl group arrangement.

Then, an amount of the preliminary reaction liquid commensurate with the supply of the aqueous solution of polyvinyl alcohol and the aldehyde is discharged by operating the extraction valve 17, and the discharged slurry-like preliminary reaction liquid is introduced into the tank-shaped reactor 2. It The degree of acetalization of the resin particles introduced into the tank reactor 2 is generally 40 mol%, preferably 55 mol%.

As the tank reactor 2, an ordinary tank reactor equipped with a stirring blade is used. The inner wall of the tank reactor 2 and other inner walls of the pipe are preferably made of glass. The stirring blade is rotated to prevent the particles from aggregating while stirring, and the aging reaction is carried out at 60 to 100 ° C. for 3 to 6 hours. When the aging reaction time is less than 3 hours, the degree of acetalization is low and the compatibility with the plasticizer is poor. On the contrary, if the aging reaction time exceeds 6 hours, the rigidity of the film becomes too high.

After the aging reaction, the slurry aging reaction liquid is cooled, neutralized by a conventional method, washed with water, and dried to produce a powdery or granular polyvinyl acetal resin. The degree of acetalization of the polyvinyl acetal resin varies depending on the application, but is generally 60 to 70 mol%.

Among the polyvinyl acetal resins thus obtained, for example, when a polyvinyl butyral resin having a butyralization degree of 65 to 67 mol% is used to produce an interlayer film of laminated glass, a plasticizer is added to the polyvinyl butyral resin. Mix and melt extrude this into a sheet, or
Alternatively, it is manufactured into a sheet by a calendar method or a pressing method.

As the plasticizer, triethylene glycol di-2-ethylbutyrate, triethylene glycol di-2-ethylhexoate, triethylene glycol dicaprylate, triethylene glycol di-n-heptate, tetraethylene glycol Di-n-heptate and the like are preferably used.

Such a plasticizer is generally mixed in the range of 30 to 60 parts by weight with respect to 100 parts by weight of the polyvinyl acetal resin. If the content of the plasticizer is less than 30 parts by weight, the penetration resistance of the laminated glass decreases. On the other hand, when the content of the plasticizer exceeds 60 parts by weight, the plasticizer oozes out and the transparency of the laminated glass is adversely affected.

A conventional adhesion modifier composed of an organic acid salt of an alkali metal such as magnesium acetate or an alkaline earth metal may be mixed with the plasticizer. Such an adhesion modifier is generally added in an amount of 0.01 to 0.5 parts by weight based on 100 parts by weight of the resin. Further, such an adhesion modifier may be applied as a solution to the surface of the plasticized polyvinyl butyral sheet and dried. In addition, known additives used for interlayer films for laminated glass, such as colorants and ultraviolet absorbers, can be added.

In order to produce a laminated glass using the thus obtained intermediate film, generally, an intermediate film is sandwiched between two glass plates, placed in, for example, a rubber bag, and pre-bonded at about 70 to 110 ° C. under reduced pressure while suctioning. After that, the main adhesion is performed in an autoclave at about 120 to 150 ° C. and a pressure of about 10 to 15 kg / cm ² .

[0029]

[Function] A polyvinyl alcohol aqueous solution and an aldehyde are preliminarily reacted at 50 to 95 ° C. while circulating in a loop reactor, and then aged at 60 to 100 ° C. with stirring in a tank reactor to give polyvinyl alcohol. In the method for producing an acetal resin, the pH of the reaction solution is 1.
0 to 1.45, the amount of aldehyde charged is increased by 3 to 15% of the theoretical amount required to obtain the desired degree of acetalization, and the average residence time of the reaction liquid circulating in the loop reactor is 4 to 8
When the aging reaction time in the tank reactor is 3 to 6 hours, the hydroxyl groups remaining in the polyvinyl acetal resin are likely to be arranged in a chain, which results in the formation of a resin having a strong molecular association by hydrogen bonds. can get. As a result, it is presumed that the self-adhesiveness of the film is reduced and the rigidity of the film is further increased while maintaining good heat fluidity as an intermediate film for laminated glass.

[0030]

EXAMPLES Examples and comparative examples of the present invention will be shown below.
Example 1 In this example, the reactor shown in FIG. 1 was used.

The polyvinyl alcohol dissolving tank 1 has a volume of 10
The aldehyde tank 3 is made of stainless steel with a volume of 6 liters. Also,
The loop reactor 10 is formed by an inner glass lining pipe having a diameter of 40 mm, and its volume is 6.7 liters. The tank reactor 2 is composed of an inner glass lining material having a volume of 100 liters.

First, 62 liters of pure water was placed in the polyvinyl alcohol dissolving tank 1 and the average degree of polymerization was 1700 and the degree of saponification was 9.
After 7,500 g of 9.0 mol% polyvinyl alcohol was charged and dispersed, the temperature was raised to 90 ° C. to completely dissolve the polyvinyl alcohol, and then the mixture was kept cooled to 80 ° C. Further, 260 g of hydrochloric acid having a concentration of 35% was added as a catalyst. The pH of the reaction solution was adjusted to 1.45 with this hydrochloric acid catalyst.

Further, 4200 g of butyraldehyde was charged into the aldehyde tank 3 and mixed well. The amount of butyraldehyde charged (supplied amount) is the target butyralization degree of 65.2.
This is a 5.27% increase of the theoretical amount necessary to obtain the mol%.

The loop reactor 10 was filled with pure water, heated and kept at 80 ° C., and the circulation pump 7 was operated for circulation. In addition, the tank reactor 2 has 11 liters of pure water and a concentration of 35
% Hydrochloric acid (62 g) was added and stirred, and this was heated and maintained at 85 ° C.

The above polyvinyl alcohol aqueous solution containing an acid catalyst and the above butyraldehyde were fed into the loop reactor 10. Both are mixed through the confluence,
The mixed reaction solution is circulated in the loop reactor 10 by the circulation pump 7 at a rate of about 1.75 l / min (about 1.63 l / min of polyvinyl alcohol aqueous solution, about 0.12 l / min of butyraldehyde) to carry out the preliminary reaction. I advanced. The supply amount of the polyvinyl alcohol aqueous solution and the butyraldehyde is 42, so that the supply of both ends in 42 minutes.
Controlled 6. The average residence time of the reaction solution circulating in the loop reactor 10 is 4 minutes, and the flow rate of the reaction solution is 4 m / sec.

Then, an amount corresponding to the supply of the polyvinyl alcohol aqueous solution and butyraldehyde is adjusted by the extraction valve 17 and discharged, and this is introduced into the tank reactor 2. Rotation speed of stirring blade of tank-shaped reactor 2 is 250 rpm, and peripheral speed of stirring blade is 2 m /
Second, while setting the operating efficiency to 10 w / liter and stirring,
After aging reaction at 85 ° C for 4 hours, it was cooled to 40 ° C.
Then, neutralize, wash with water, and dry in the usual way to obtain a particle size of 500-10.
A 00 μm granular polyvinyl butyral resin was prepared.

The degree of butyralization of the obtained polyvinyl butyral resin was measured and calculated based on JIS K 6728. The degree of butyralization was 65.2 mol%.
100 parts by weight of this polyvinyl butyral resin is mixed with triethylene glycol di-2-ethylbutyrate as a plasticizer.
After adding 40 parts by weight and kneading this with a Raiki machine, the thickness
The film was placed in a 0.76 mm frame and pressed at a temperature of 150 ° C. and a pressure of 100 kg / cm ² for 30 minutes to produce an interlayer film made of a transparent plasticized polyvinyl butyral sheet having a thickness of 0.76 mm.

This interlayer film was placed in a constant temperature and humidity chamber at a temperature of 25 ° C. and a humidity of 23% RH for 3 hours, and this was used with a Koka type flow tester (Koka type flow tester FT-500 type manufactured by Shimadzu Corporation). The melt viscosity at 110 ° C. was measured under the conditions of a nozzle diameter of 1 mm, a nozzle length of 1 mm and a plunger pressure of 20 kg / cm ² . 1
The melt viscosity at 10 ° C. was 295 × 10 ⁴ poise. In addition, the rigidity that can smoothly cut the interlayer film has a melt viscosity of 110 ° C.
It has been confirmed by experiments that it is in the range of 250 × 10 ^{4 to} 350 × 10 ⁴ poise.

Further, in order to evaluate the self-adhesiveness of the membrane members,
Two pieces of the above interlayer film are cut into 15 cm x 15 cm squares, and after stacking them, a load of 2.8 kg is placed at a temperature of 20 ° C.
The sample was left for 20 hours in a constant temperature and humidity chamber with a humidity of 23% RH, and a T-type peeling force of 90 degree angle was measured with a tensile tester at a pulling speed of 500 mm / min to determine self-adhesion. This self-adhesion was 0.40 kg / cm 2. It has been confirmed by experiments that the self-adhesive force at which the membranes do not adhere to each other is 0.50 kg / cm or less.

The above results are summarized in Table 1. By the way, this plasticized polyvinyl butyral sheet was used as an interlayer film, which was sandwiched between glass plates of thickness 2.5 mm × length 30 cm × width 30 cm, which was put in a rubber bag and the degree of vacuum 600 mm.
Pre-bonded by degassing at Hg and temperature of 80 ℃. After that, main bonding was carried out for 20 minutes under the conditions of a temperature of 140 ° C. and a pressure of 13 kg / cm ^{2 in} an air type autoclave to prepare laminated glass. No work problems occurred. Further, the interlayer film of this laminated glass was evenly flowed over the entire surface, and no residual air was observed.

Example 2 In Example 1, the pH of the reaction solution with an acid catalyst was set to 1.0. Other than that was performed like Example 1. The results are summarized in Table 1.

Example 3 In Example 1, the aging reaction time in the tank reactor was set to 6 hours. Other than that was performed like Example 1. The results are summarized in Table 1.

Example 4 In Example 1, polyvinyl alcohol was 7000 g. The aging reaction time in the tank reactor was set to 6 hours. Other than that was performed like Example 1. The results are summarized in Table 1.

Example 5 In Example 1, the aging reaction time in the tank reactor was set to 6 hours. The average residence time in the loop reactor is 6
Minutes and minutes. Other than that was performed like Example 1. The results are summarized in Table 1.

Example 6 In Example 1, polyvinyl alcohol was 7000 g. The average residence time in the loop reactor was 6 minutes. Other than that was performed like Example 1. The results are summarized in Table 1.

Example 7 In Example 1, the pH of the reaction solution with an acid catalyst was set to 1.0. The average residence time in the loop reactor was 6 minutes. Other than that was performed like Example 1. The results are summarized in Table 1.

Comparative Example 1 In Example 1, the pH of the reaction solution with an acid catalyst was set to 2.0. In addition, butyraldehyde was set to 4600 g. Also,
The average residence time in the loop reactor was 10 minutes. The aging reaction time in the tank reactor was set to 4 hours. Other than that was performed like Example 1. The results are summarized in Table 1.

Comparative Example 2 In Example 1, the pH of the reaction solution using the acid catalyst was set to 2.0. In addition, butyraldehyde was set to 4600 g. Also,
The average residence time in the loop reactor was 10 minutes. The aging reaction time in the tank reactor was set to 4 hours. Other than that was performed like Example 1. The results are summarized in Table 1.

Comparative Example 3 In Example 1, the pH of the reaction solution using the acid catalyst was set to 0.5. Moreover, polyvinyl alcohol was set to 7,000 g. The average residence time in the loop reactor was set to 10 minutes.
The aging reaction time in the tank reactor was set to 2 hours. Other than that was performed like Example 1. The results are summarized in Table 1.

Comparative Example 4 In Example 1, the average residence time in the loop reactor was
10 minutes. In addition, the aging reaction time in the tank reactor is 4
It was time. Other than that was performed like Example 1. The results are summarized in Table 1.

Comparative Example 5 In Example 1, the average residence time in the loop reactor was
10 minutes. Also, the aging reaction time in the tank reactor is 6
It was time. Other than that was performed like Example 1. The results are summarized in Table 1.

Comparative Example 6 In Example 1, the average residence time in the loop reactor was set to 7 minutes. Also, the aging reaction time in the tank reactor is 6
It was time. Other than that was performed like Example 1. The results are summarized in Table 1.

Comparative Example 7 In Example 1, the pH of the reaction solution using the acid catalyst was set to 2.0. The average residence time in the loop reactor was 6 minutes. Other than that was performed like Example 1. The results are summarized in Table 1.

[0054]

[Table 1]

[0055]

As described above, while the vinyl alcohol aqueous solution and the aldehyde are circulated in the loop reactor, 50 to 50
In the method for producing a polyvinyl acetal resin by preliminarily reacting at 95 ° C and then aging reaction at 60 to 100 ° C while stirring in a tank reactor, the pH of the reaction solution is adjusted to 1.0 to 1.45 with an acid catalyst, The amount of aldehyde charged is 3 to 15 of the theoretical amount necessary to obtain the desired degree of acetalization.
%, The average residence time of the reaction liquid circulating in the loop reactor is set to 4 to 8 minutes, and the aging reaction time in the tank reactor is set to 3 to 6 hours. The self-adhesiveness and rigidity are improved together with the heat fluidity of the membrane,
It is possible to produce a polyvinyl acetal resin that does not adhere to each other and can smoothly cut the film.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing an example of a reaction apparatus used in the present invention.

[Explanation of symbols]

 1 Polyvinyl alcohol dissolution tank 2 Tank reactor 3 Aldehyde tank 4 Supply pipe 5 Transfer pipe 6 Supply pipe 7 Circulation pump 10 Loop reactor 14 Supply pump 16 Supply pump 17 Extraction valve

Claims (1)

[Claims] 1. A polyvinyl alcohol aqueous solution and an aldehyde are preliminarily reacted at 50 to 95 ° C. while circulating in a loop reactor, and then 60 to 10 while being stirred in a tank reactor.
In the method for producing a polyvinyl acetal resin by performing an aging reaction at 0 ° C, the pH of the reaction solution is adjusted to 1.0 to 1.45 with an acid catalyst, and the amount of aldehyde charged is the theoretical amount necessary to obtain the desired degree of acetalization. 3 to 15%
And the average residence time of the reaction liquid circulating in the loop reactor is 4 to 8 minutes, and the aging reaction time in the tank reactor is 3 to 6 hours. A method for producing a polyvinyl acetal resin.