JPS6053042B2 - Method for producing polyvinyl butyral - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing polyvinyl butyral, and more specifically, it has excellent transparency and thermal stability, and when an interlayer film for laminated glass is produced by adding a plasticizer, the interlayer films have a high adhesiveness to each other at room temperature. The present invention relates to a method for producing polyvinyl butyral that provides an interlayer film for laminated glass with greatly improved self-adhesion properties (hereinafter referred to as interlayer film self-adhesion).

The precipitation method, which is widely used industrially to produce polyvinyl butyral, is, for example, adding butyraldehyde to an aqueous solution of polyvinyl alcohol in the presence of an acid catalyst at 20°C.
A condensation reaction is caused in the following relatively low temperature range to produce fine precipitates of polyvinyl butyral, and then the temperature of the reaction system is raised to obtain a predetermined degree of butyralization from 20°C to 40°C.
A common method is to maintain the temperature for a long period of time.

However, the interlayer film for laminated glass obtained by adding a plasticizer to polyvinyl butyral produced by the conventional method has a strong adhesive surface, which causes the films to stick to each other when being rolled after film formation. In order to prevent such adhesion, anti-adhesive agents such as bicarbonate of soda are sprayed on the membrane surface, and
The interlayer film is cooled to a temperature below .degree.

The method of spraying an anti-adhesive agent has the disadvantage that it requires a washing process and a drying process to remove the anti-adhesive agent before bonding the polyvinyl butyral film and glass. The process ranges from interlayer film production to packaging,
This method requires a refrigeration system for transportation, storage, and use, and is expensive, so the emergence of an interlayer film that does not self-adhere at room temperature has been awaited.

In view of the above-mentioned current situation, the present invention has been developed for laminated glass, which has excellent transparency and thermal stability, and whose self-adhesiveness is greatly improved when an interlayer film for laminated glass is produced by adding a plasticizer to the obtained polyvinyl butyral. The purpose of this invention is to provide a method for producing polyvinyl butyral from which an interlayer film can be obtained, and the gist thereof is a method for producing polyvinyl butyral by condensing polyvinyl alcohol and butyraldehyde in an aqueous phase in the presence of an acid catalyst. , the reaction system is maintained at a temperature of 20°C or lower to precipitate a precipitate, and then the temperature is raised, and the reaction system is maintained at a temperature of 30'C or higher in the presence of a perchloric acid compound for thermal formation. The present invention is characterized by a method for producing polyvinyl butyral.

The average degree of polymerization of the polyvinyl alcohol used in the present invention is preferably 800 to 3000, and the degree of saponification is preferably 95 mol% or more, particularly preferably part mol%, in order to obtain polyvinyl butyral with good transparency. That's all.

The concentration of the aqueous solution of polyvinyl alcohol is not particularly limited as long as it can carry out the acetalization reaction, but it is usually 3 to 1% by weight. As for the acid catalyst used in the present invention, acids known to have the effect of condensing polyvinyl alcohol and butyraldehyde can be appropriately used, such as inorganic acids such as sulfuric acid, nitric acid, and hydrochloric acid, and valatoluenesulfonic acid. Examples include organic acids.

The amount of acid catalyst used is such that the concentration at the end of the reaction is 0.5.
A desirable amount is 5% by weight. The required amount of catalyst may be added at once, but in order to precipitate fine polyvinyl butyral, it is preferable to add the catalyst in portions at appropriate times. For example, in the case of hydrochloric acid, it is preferable to add 1/20 to 1/3 of the total required weight before precipitation, and add the remainder after precipitation. In the present invention, the amount of butyraldehyde condensed with polyvinyl alcohol is appropriate depending on the desired degree of butyralization of polyvinyl butyral. However, when polyvinyl butyral is used as an interlayer film for laminated glass, the degree of butyralization is 60.
It is desirable that the amount is from 75 mol% to 75 mol%, and for that purpose it is preferable to add 74 parts of butyraldehyde to 10 parts of polyvinyl alcohol. The perchloric acid compound in the present invention refers to perchloric acid and its salts. Preferred examples of perchlorates include alkali metal salts such as sodium perchlorate and potassium perchlorate, and magnesium perchlorate. and alkaline earth metal salts such as calcium perchlorate, with sodium perchlorate being particularly preferred.

These perchloric acid compounds are used alone or in combination, and the amount used is usually 0.2 to 1% by weight in the final system, but is not limited to this amount. do not have. Also, the time to add perchloric acid compound to the reaction system is from before the precipitation of polyvinyl butyral.
Although it can be done at any time immediately after the reaction system is heated to a temperature of 30°C or higher after the precipitation of the precipitate, butyraldehyde is usually added to the polyvinyl alcohol aqueous solution to which it has not yet been added together with an acid catalyst at the start of the reaction. It is better to do so.

To produce polyvinyl butyral by the method of the present invention, an acid catalyst is usually added to an aqueous polyvinyl alcohol solution at a temperature of over 200°C, then the above perchloric acid compound is added, the reaction system is cooled, and butyraldehyde is added. A condensation reaction is carried out to precipitate polyvinyl butyral at a temperature of 20° C. or lower.

The reason why the temperature of the reaction system is kept low during precipitation is to obtain the precipitate in the form of fine particles or powder.

The lower limit of the temperature below 20'C is not particularly limited as long as the reaction system does not freeze, but a temperature of -6C or above is usually employed.

Next, after precipitation of polyvinyl butyral, the temperature of the reaction system is raised and maintained at a temperature of 30°C or higher to further advance the reaction, usually in the presence of a perchloric acid compound. The reaction product is neutralized with a base, and the reaction product is extracted and washed and purified using conventional methods.

The upper limit of the temperature during thermal formation is not particularly determined, but in order to prevent excessive evaporation of the aldehyde, a temperature of 9 or below is preferable, and the thermal formation time is also not particularly specified, but is usually 1 hour. It is said to last from 1 hour to 1 hour.

In this way, transparency and thermal stability can be improved by precipitating a precipitate at a temperature of 2CfC or less and then thermally forming it by keeping the reaction system at a temperature of 30°C or more in the presence of the above-mentioned perchloric acid compound. Although the reason why excellent polyvinyl butyral can be obtained and why an interlayer film with improved properties such as self-adhesion can be obtained by plasticizing the polyvinyl butyral is still not fully clear, the presence of the above-mentioned perchloric acid compound By thermally forming the hydroxyl groups in polyvinyl alcohol, the butyralization reaction is more likely to occur selectively in other parts than in parts where the hydroxyl groups in polyvinyl alcohol have a strong tendency to associate due to hydrogen bonds arranged in a chain. It is thought that this increases the tendency for hydroxyl groups to remain in a chain in the molecule, thereby increasing the rigidity of the obtained polyvinyl butyral, which contributes to a decrease in self-adhesion.

In addition, regarding transparency and thermal stability, the present inventors have found that self-adhesion is improved by thermally forming the precipitate at a relatively high temperature and for a long time even in the absence of the above-mentioned perchloric acid compound. We have found that an interlayer film can be obtained, but in this case, the precipitated particles tend to become coarse due to agglomeration, and the acid catalyst and the base used for its neutralization remain in the coarse particles. There was a tendency for transparency and thermal stability to decrease. On the other hand, since the above-mentioned perchloric acid compound has the effect of preventing the coarsening of the fine particles precipitated at a temperature of 2 CfC or lower, in the present invention, the final product is polyvinyl which has excellent transparency and thermal stability. It is believed that butyral is obtained. The plasticizer used for the polyvinyl butyral obtained by the method of the present invention can be any of those conventionally used as plasticizers for polyvinyl butyral, such as triethylene glycol di-2-ethyl butyrate, triethylene glycol di-2-ethyl butyrate, triethylene glycol di-2-ethyl butyrate, triethylene glycol di-2-ethyl butyrate, 2-ethylhexoate and the like are preferably used.

The amount of plasticizer added is preferably 30 to 60 parts by weight per 100 parts by weight of polyvinyl butyral. If the amount of plasticizer is less than 3 parts, the penetration resistance will decrease when used as an interlayer film for laminated glass, and if the amount of plasticizer is more than 6 parts, the so-called bleed phenomenon will occur where the plasticizer seeps onto the film surface. This is because it adversely affects transparency and adhesiveness when used as an interlayer film for laminated glass. The method of the present invention is constructed as described above, in which the reaction system is maintained at a temperature of 2 or below to precipitate a precipitate, and then the temperature is raised, and the reaction system is heated in the presence of the above-mentioned perchloric acid compound. According to the present invention, since the particles are thermally formed by maintaining the particles at a temperature of 3CfC or higher, components such as acid catalysts and bases, which are mostly contained in the coarse particles, do not remain in the coarse particles, resulting in transparency. , polyvinyl butyral with excellent thermal stability is obtained,
Furthermore, when an interlayer film for laminated glass is produced by adding a plasticizer to the polyvinyl butyral, an interlayer film for laminated glass with significantly improved self-adhesion can be obtained, and furthermore, if this interlayer film is used, a laminated glass film with excellent sanitary resistance can be obtained. Glass is obtained.

Examples of the present invention are shown below. % simply means weight %
means. In addition, each physical property value in Examples was based on the following measuring method. 1 viscosity distribution polyvinyl butyral 100f 4, 16, 28, 48
, 60, 80, and 100 mesh numbers, and the weight of the resin remaining on each sieve was measured.

2 A sample obtained by sandwiching transparent polyvinyl butyral 30y between two 10 (triangular glass plates) was placed in an open chamber kept at a temperature of 160°C for 5 minutes to melt the polyvinyl butyral, and then allowed to cool at room temperature. did.

The obtained sample was observed under white light, and those without bluishness, turbidity, etc. were evaluated as good. 3 Immerse a test tube containing thermostable polyvinyl butyral 1y in a heated oil bath,
A case where the polyvinyl butyral did not change color even after 5 hours at ℃ was considered to have good thermal stability.

Generally, when neutralization or water washing is incomplete, catalysts such as hydrochloric acid remain in polyvinyl butyral, and when this test is performed, polyvinyl butyral is colored yellow.

4 Add 4 parts of a predetermined plasticizer to 10 parts of self-adhesive polyvinyl butyral, mix into 1 powder using a Raikai machine, and mix using a roll for 12 parts.
After kneading for 3 minutes at 0C, 1500C140k9/Cl
Press at t for 3 minutes and the surface will have a smooth thickness of 0.76? A uniform film was created.

Is this film 30X1? It was cut into a rectangular shape, and two sheets were placed one on top of the other and left in a desiccator kept at a temperature of 200° C. under a load of 6k9 for 4 hours. One end of the sample obtained in this way is peeled off from each other, the peeled film is bent in a 900 direction to make the whole into a T shape, and both ends of the peeled film are grabbed with a tensile/testing machine 2C) 90 test peel strength was measured at a tensile speed of 500 m/min.

5. Add and knead 42 parts by weight of plasticizer to 10 parts by weight of impact-resistant polyvinyl butyral, and use an extruder to obtain a thickness of 0.76T! f! R
A plasticized polyvinyl butyral was obtained.

This film was sandwiched between two glass plates with a thickness of 3.0 m, 130 C, and 71 x 30 d.
One powder was heated and pressed under the conditions of kg/d to obtain a laminated glass. After storing this laminated glass at a specified temperature for more than 8 hours,
The outer frame is 31 (7 ft.
A steel ball (bond) was dropped from a specified height onto the center of the laminated glass. The percentage of steel balls penetrating laminated glass is 5
The height at which the value was 0% was defined as the penetration resistance strength.

The laminated glass sample used was one in which the pummel value, which will be described later, was set to 6, which is within the range normally used as a product, by using a plasticizer mixed with an appropriate amount of metal soap.

6 Adhesion to Glass Laminated glass was adjusted by leaving it at a temperature of -1 (s) ± 0.6°C for f hours, and then struck with a hammer with a head weighing 0.45 kg until the particle size of the glass was 61a or less. I smashed it until it became.

The degree of exposure of the film after the glass was peeled off was determined using limit samples that had been graded in advance, and the results were expressed as pummel values according to Table 1. Example 1 1kg of concentrated hydrochloric acid (hydrochloric acid concentration 35%) was added to 100k9 of a 1% aqueous solution of polyvinyl alcohol with a degree of saponification of 99.2 mol% and a degree of polymerization of 1700.
and 5k9 of a 60% aqueous solution of sodium perchlorate (
The sodium perchlorate concentration in the final system was 4.2%), 1 (3C
When three powders of butyraldehyde 5.1k9 were added dropwise while stirring, white fine particles of polyvinyl butyral were precipitated.

Further, 7k9 of 35% concentrated hydrochloric acid was added, and the reaction system was heated to 35°C at a heating rate of 8°C/hour while stirring, and the temperature was maintained for an additional time to perform thermal formation, and then sodium hydroxide was added. The reaction system was neutralized to a pH of 9.6. The obtained resin was washed with water and dried according to a conventional method to obtain a white fine powder.

The degree of butyralization of this polyvinyl butyral is 62.0
It was %. The physical properties of the polyvinyl butyral thus obtained and the interlayer film and laminated glass obtained by adding triethylene glycol di-2-ethyl butyrate as a plasticizer to the polyvinyl butyral were as shown in Table 2.

Example 2 In Example 1, the amount of butyraldehyde added was 5.2k.
A white powder was obtained in the same manner as in Example 1 except that the reaction system was maintained at a thermal formation temperature of 40 C for 5 hours.

The degree of butyralization of the polyvinyl butyral thus obtained was 63.3 mol %, and its physical properties were as shown in Table 2.

Example 3 In Example 1, 5 kg of 60% magnesium perchlorate aqueous solution was used instead of 5 kg of sodium perchlorate aqueous solution,
A white powder was obtained in the same manner as in Example 1 except that the thermal formation temperature was 48° C. and the thermal formation time was 8 hours.

The degree of butyralization of the polyvinyl butyral thus obtained was 62.2 mol%, and its physical properties were as shown in Table 3.

Example 4 Butyraldehyde 5.5k9, sodium perchlorate 60
% aqueous solution (concentration 0.6 in the final system)
%), a white powder was obtained in the same manner as in Example 1 except that the thermal formation temperature was 60° C. and the thermal formation time was 3 hours.

The polyvinyl butyral thus obtained had a butyral degree of 65.8 mol%, and its physical properties were as shown in Table 4. Example 5 Using 5.6 kg of butyraldehyde, the thermal formation temperature was 70 C.
A white powder was obtained in the same manner as in Example 1 except that the reaction system was kept for 3 hours.

The polyvinyl butyral thus obtained had a degree of butyralization of 67.7 mol%, and its properties were as shown in Table 4. Comparative Example 1 Polyvinyl butyral powder was obtained in the same manner as in Example 1 except that sodium perchlorate was not added.

Its physical properties were as shown in Table 5.
*Comparative Example 2) Polyvinyl butyral powder was obtained in the same manner as in Example 5 except that sodium perchlorate was not added.

Claims (1)

[Claims] 1. A method for producing polyvinyl butyral by condensing polyvinyl alcohol and butyraldehyde in an aqueous phase in the presence of an acid catalyst, in which a precipitate is precipitated by maintaining the reaction system at a temperature of 20°C or less. A method for producing polyvinyl butyral, which comprises heating the reaction system and thermally forming the reaction system at a temperature of 30° C. or higher in the presence of a perchloric acid compound. 2 The concentration of perchloric acid compound in the final reaction system is 0.
The manufacturing method according to claim 1, wherein the content is 2% by weight or more. 3. Claim 1 or 2, wherein the perchloric acid compound is at least one of perchloric acid, an alkali metal salt of perchloric acid, and an alkaline earth metal salt of perchloric acid. Production method. 4. The manufacturing method according to claim 3, wherein the alkali metal salt of perchloric acid is sodium perchlorate. 5. The manufacturing method according to any one of claims 1 to 3, wherein the reaction system is maintained at a temperature of 30° C. or higher for 1 to 15 hours for thermal formation.