JPS6358844B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing polyvinyl butyral, and more specifically, when an interlayer film for laminated glass is produced by adding a plasticizer, the adhesion between the interlayer films at room temperature (hereinafter referred to as self-adhesion of the interlayer film) is reduced. The present invention relates to a method for producing polyvinyl butyral from which an interlayer film for glass can be obtained. Polyvinyl butyral is used as an interlayer film for laminated glass,
It is widely used as a raw material for adhesives, paints, etc., but when used as an interlayer film for laminated glass, properties such as high transparency and heat resistance stability are particularly required. In addition, interlayer films for laminated glass obtained by adding a plasticizer to polyvinyl butyral produced by conventional precipitation or dissolution methods have strong adhesion on the surface of the film, so the films may stick together during winding after film formation. In order to prevent such adhesion, methods such as spraying an anti-tack agent such as sodium bicarbonate on the surface of the film or cooling the interlayer film to a temperature of 10° C. or lower have been carried out. However, since all of these methods have various drawbacks, the emergence of an interlayer film that is substantially free of self-adhesion at room temperature has been awaited. The present inventors have developed polyvinyl butyral obtained by, for example, precipitating fine precipitates of polyvinyl butyral at a relatively low temperature in a precipitation method, and then raising the temperature of the reaction system and aging at a high temperature for a long time. We have already found that adding a plasticizer can produce an interlayer film with reduced self-adhesion, but in this case, depending on the aging temperature or time conditions, precipitated particles may aggregate due to The particles tend to become coarse, resulting in a decrease in transparency and heat resistance stability. On the other hand, JP-A No. 54-22489 discloses that polyvinyl butyral is treated at high temperature in an aqueous medium in the presence of 0.01 to 0.5% by weight of an organic sulfonic acid based on the polyvinyl butyral to obtain highly transparent polyvinyl butyral. It is disclosed that polyvinyl butyral sheets with reduced tack can be obtained. However, in this method, it is thought that this is due to the difficulty in sufficiently removing the above amount of organic sulfonic acid from the resin by washing, but the obtained polyvinyl butyral has good transparency and heat resistance stability. It was difficult to use it practically as an interlayer film because of its insufficient properties. In view of the above-mentioned current state of the method for producing polyvinyl butyral, the present invention aims to obtain polyvinyl butyral with good transparency and heat resistance under industrially advantageous conditions, and to add a plasticizer to the obtained polyvinyl butyral to form a laminated glass. The purpose of this paper is to provide a method for producing polyvinyl butyral that produces an interlayer film for laminated glass with reduced self-adhesion. Self-adhesion characterized by heating butyral dispersed in an aqueous phase to a temperature of 30°C or higher in a strongly acidic region in the presence of a nonionic surfactant and maintaining the temperature at 30°C or higher. The present invention relates to a method for producing polyvinyl butyral having reduced properties. The polyvinyl butyral used in the present invention may be polyvinyl acetate as a starting material as long as it is obtained by acetalizing polyvinyl alcohol. Widely used. However, since it is dispersed in the aqueous phase, it is preferred to use polyvinyl butyral which is also produced in the aqueous phase.
In this case, it is particularly preferred industrially to react polyvinyl alcohol and butyraldehyde in the presence of an acid catalyst to precipitate polyvinyl butyral in the aqueous phase, without separating the resin from the reaction system. This means post-treatment in the same aqueous phase. However, it is also possible to use dry polyvinyl butyral powder obtained by conventionally known methods such as precipitation or dissolution. As for the polyvinyl butyral used in the present invention, when polyvinyl butyral obtained by keeping the temperature at 30°C or higher is used as an interlayer film for laminated glass, it is desirable that the degree of butyralization is 60 to 75 mol%. The degree of oxidation is 95 mol% or more, and
It is preferable that the resin be made from polyvinyl alcohol containing 98 mol% or more, since a resin with good transparency can be obtained in the end. In addition, if the average degree of polymerization of polyvinyl alcohol at this time is too low, the effect of improving self-adhesion when forming an interlayer film by adding a plasticizer is poor, and if it is too high, the viscosity is high, which is inconvenient for industrial acetalization. Therefore, it is usually 800~
3000 are used. Examples of nonionic surfactants used in the present invention include polyoxyethylene alkyl ether, polyoxyethylene alkylaryl ether (typical example polyoxyethylene alkyl phenyl ether), polyoxyethylene alkyl ester, and polyoxyethylene sorbitan. Examples include polyoxyethylene activators such as fatty acid esters, polyoxyethylene-polyoxypropylene glycol, and polyhydric alcohol activators such as sorbitan fatty acid esters. More specifically, the general formula R—O—(CH ₂ CH ₂ O—) _o H (R is an alkyl group having 4 to 30 carbon atoms, an alkylaryl group having 1 to 30 carbon atoms, aryl group) or alkyl has 4 to 30 carbon atoms
represents an acyl group, and n represents an integer of 1 to 15. ) are preferably used, and among these, active agents having an HLB (hydrophilic-lipophilic balance) of 14 or less are particularly preferably used. The surfactant represented by the above general formula has excellent compatibility with polyvinyl butyral resin and the plasticizer described below, so even if it remains in the resin without being sufficiently removed in the washing process after the reaction, it becomes transparent. In addition, those with an HLB of 14 or less have particularly good heat resistance, so they do not stain the interlayer film or laminated glass. These nonionic surfactants are used alone or in combination, and the amount used is usually determined by the concentration in the final system of the polyvinyl butyral dispersion.
The amount should preferably be 0.03 to 1.0% by weight, but
It is not limited to this range. It is preferable to add the nonionic surfactant to the polyvinyl butyral dispersion before a long period of time has elapsed at a high temperature after polyvinyl alcohol is acetalized, in order to suppress coarsening of the polyvinyl butyral particles. In the present invention, in order to obtain a polyvinyl butyral dispersion in a strongly acidic region, conventionally known hydrochloric acid, sulfuric acid,
An inorganic acid such as nitric acid or an organic acid such as balatoluenesulfonic acid can be used, and the strongly acidic region is usually defined as a PH range, although it depends on the temperature of the polyvinyl butyral dispersion.
2 or less, preferably PH1 or less. Furthermore, when it is necessary to increase the degree of butyralization of polyvinyl butyral, the degree of butyralization can be increased by making a predetermined amount of butyraldehyde exist in the dispersion. In addition, the upper limit of the temperature for ripening polyvinyl butyral is not particularly set, but it is generally set at 90°C or lower, and 30°C or lower.
The time for maintaining the temperature at or above .degree. C. is usually 1 to 15 hours, including the time for raising and lowering the temperature of the dispersion. or,
When attempting to produce a resin that yields an interlayer film with almost no self-adhesion at room temperature, it is preferable to maintain the resin at a temperature of 40° C. or higher for 6 hours or longer. To produce polyvinyl butyral by the method of the present invention, usually an acid catalyst is added to an aqueous polyvinyl alcohol solution at a temperature exceeding 20°C, the reaction system is then cooled, and butyraldehyde is added to cause a condensation reaction to precipitate polyvinyl butyral. Polyvinyl butyral is prepared by precipitating it at a low temperature such as 20°C or lower and dispersing it in an aqueous phase. In this way, the temperature of the reaction system is kept low during precipitation in order to obtain the precipitate in the form of fine particles or powder, and the lower limit of the temperature should be a temperature that does not freeze the reaction system, and there are no particular restrictions. Although it is not something that will be done,
Usually a temperature of -6°C or higher is employed. Next, while the pH of the reaction system is 2 or less, a nonionic surfactant is added and the reaction system is heated up and kept at a temperature of 30°C or higher to further advance the reaction, and then the catalyst is neutralized with a base. The reaction product is taken out and washed and purified using conventional methods. When producing polyvinyl butyral with reduced self-adhesion, after precipitating fine particles of polyvinyl butyral, the reaction system is heated to a temperature exceeding 40°C in the absence of the nonionic surfactant mentioned above. When aged at a low temperature, for example, the precipitated particles tend to become coarse due to agglomeration, resulting in a decrease in transparency and thermal stability.On the other hand, when aged at a low temperature of, for example, around 30°C, coarsening of the particles is less likely to occur. The disadvantage was that it required an extremely long time to ripen. On the other hand, when the nonionic surfactant of the present invention is used, even when aged at temperatures exceeding 40°C,
It is assumed that this is because the nonionic surfactant has the effect of suppressing the coarsening of fine particles, and a resin with good transparency and thermal stability can be obtained. The ripening time is greatly reduced. As the plasticizer used for the polyvinyl butyral obtained by the method of the present invention, any of those conventionally used as a plasticizer for polyvinyl butyral can be used, such as triethylene glycol di2-ethyl butyrate, triethylene glycol In addition to general-purpose plasticizers such as di-2-ethylhexoate, dibutoxydiethylene glycol adipate and the like are preferably used. The amount of plasticizer added is 30 to 100 parts by weight of polyvinyl butyral.
60 parts by weight is desirable. If the plasticizer content is less than 30 parts by weight, the penetration resistance will decrease when used as an interlayer film for laminated glass, and if the plasticizer content exceeds 60 parts by weight, a so-called bleed phenomenon will occur in which the plasticizer seeps onto the film surface, resulting in poor performance of laminated glass. This is because it has an adverse effect on transparency and adhesion when used as an interlayer film. The method of the present invention is configured as described above, and according to the present invention, the particles are fine and have good transparency and thermal stability, and when an interlayer film for laminated glass is produced by adding a plasticizer, Polyvinyl butyral, which provides an interlayer film for laminated glass with reduced self-adhesion, can be obtained under industrially advantageous temperature and time conditions as described above, compared to when the nonionic surfactant is not used. It is possible. Examples of the present invention are shown below. % simply means weight %. In addition, each physical property value in Examples was based on the following measuring method. 1 Particle size distribution 100g of polyvinyl butyral is 4, 16, 28,
Classify with sieves with mesh numbers of 48, 60, 80, and 100,
The weight of the resin remaining on each sieve was determined. 2. Degree of butyralization The resin at each stage of ripening was extracted, and the pH was immediately adjusted to 8.6 with a weak alkali, and the resulting resin was purified and dried and measured in accordance with JISK6728-5.52. 3 Thermal Stability Thermal stability was determined to be good if the test tube containing polyvinyl butyral was immersed in a heated oil bath and the polyvinyl butyral did not change color even after a predetermined period of time at 120°C. 4 Transparency A sample obtained by sandwiching polyvinyl butyral between two glass plates was placed in a heated oven to melt the polyvinyl butyral, and then allowed to cool at room temperature. The obtained sample was observed under white light, and those without bluishness, turbidity, etc. were evaluated as good. 5 Self-adhesiveness of interlayer film Add 42 parts by weight of a specified plasticizer to 100 parts by weight of polyvinyl butyral, mix for 15 minutes in a Raikai machine, and knead for 3 minutes at 120°C using a roll.
A uniform film with a smooth surface and a thickness of 0.76 mm was prepared by pressing at 150° C. and 40 kg/cm ² for 3 minutes.
Cut this film into a rectangular shape of 3cm x 10cm, stack the two pieces together and apply a load of 6kg.
It was left for 48 hours in a desiccator kept at a temperature of 20°C. One end of the sample obtained in this way was peeled off from each other, and the peeled film was bent in a 90° direction to form a T-shape. Then, both ends of the peeled film were held in a tensile tester and heated at 20°C. The T-peel strength was measured at a tensile speed of 500 mm/min. Example 1 15 kg of polyvinyl alcohol with a degree of saponification of 99.4 mol% and a degree of polymerization of 1700 was dispersed in 85 kg of water and heated while stirring to obtain a 15% aqueous solution of polyvinyl alcohol. Add 1.0 kg of hydrochloric acid with a concentration of 35% to this aqueous solution,
When 8.0 kg of butyraldehyde was added dropwise to the mixture over a period of 30 minutes while stirring at 13°C, fine white particles of polyvinyl butyral were precipitated. Furthermore, after adding 7.6 kg of 35% concentrated hydrochloric acid to reduce the pH of the reaction system to 0.5 or less, use it as a nonionic surfactant.

[Formula] (HLB is 8) 700g dissolved in 3Kg of water is added (surfactant concentration is 0.58% in the final system), the temperature is raised to 45℃ at 25℃/hour, and the temperature is maintained for another 8 hours. It was kept and aged. This system was neutralized by adding sodium hydroxide to a pH of 8.5. The aging time in a strongly acidic region at a temperature above 30°C was 9 hours. 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 polyvinyl butyral at this time was 65.1 mol%. The particle size distribution, thermal stability, and transparency of the polyvinyl butyral resin and the self-adhesion of the plasticized polyvinyl butyral interlayer were as shown in Table 1. Note that triethylene glycol di-2-ethyl butyrate was used as the plasticizer. Example 2 In Example 1

Instead of [formula], C ₁₂ H ₂₅ -O--(CH ₂ CH ₂ -O-) ₂ H (HLB is 5)
A white powder was obtained in the same manner as in Example 1, except that the mixture was kept at an aging temperature of 55° C. for 5 hours. The degree of butyralization of the resulting resin was 65.1 mol%, and its physical properties were as shown in Table 1. Example 3 (Reference Example 1) Add 1 kg of 35% hydrochloric acid to 100 kg of a 13% aqueous solution of polyvinyl alcohol with a degree of saponification of 99.6 mol% and a degree of polymerization of 1700, and add 6.7 kg of butyraldehyde to 30 kg at 13°C.
When the solution was added for a few minutes, white fine particles of polyvinyl butyral were precipitated. Further, 7 kg of hydrochloric acid with a concentration of 35% was added, and the reaction system was heated to 30° C. at a rate of 20° C./hour while stirring, and after being maintained at that temperature for 3 hours, it was washed with neutralized water in a conventional manner. The degree of butyralization at this time was 65.8 mol%. The obtained results are shown in Table 1 as Reference Example 1.
Add 8 kg of 35% concentrated hydrochloric acid to 84 kg of a 0.5% aqueous solution of the nonionic surfactant Neugen EA80 (Daiichi Pharmaceutical Chemical Co., Ltd.) and add polyvinyl butyral 10 obtained above.
The polyvinyl butyral was post-treated by dispersing Kg and keeping at a temperature of 45° C. for 4 hours. Table 1 shows the physical properties of the resin obtained by neutralizing, washing with water, and drying. Comparative Example 1 Polyvinyl butyral powder was obtained in the same manner as in Example 1 except that no surfactant was used. Its physical properties were as shown in Table 1. Comparative Example 2 A white powder of polyvinyl butyral was obtained in the same manner as in Example 2 except that no surfactant was added. Its physical properties are shown in Table 1. Comparative Example 3 Polyvinyl butyral powder was obtained in the same manner as in Example 3, except that the resin obtained in Reference Example 1 was post-treated without adding any surfactant. Its physical properties are shown in Table 1.

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Claims (1)

[Scope of Claims] 1 Polyvinyl butyral produced by acetalization of polyvinyl alcohol is dispersed in an aqueous phase and the temperature is raised to 30°C or higher in a strongly acidic region in the presence of a nonionic surfactant. A method for producing polyvinyl butyral with reduced self-adhesion, characterized by maintaining the temperature at 30°C or higher. 2 Nonionic surfactants have the general formula R-O-(CH ₂ CH ₂ O-) _o H (R is an alkyl group with 4 to 30 carbon atoms, an alkylaryl group with 1 to 30 carbon atoms in the alkyl group) or an acyl group whose alkyl group has 4 to 30 carbon atoms;
n represents an integer from 1 to 15. ) The manufacturing method according to item 1, which is a compound represented by: 3. The manufacturing method according to item 1 or 2, wherein the nonionic surfactant has an HLB of 14 or less. 4. The manufacturing method according to any one of Items 1 to 3, wherein the concentration of the nonionic surfactant in the final system of the dispersion is 0.03 to 1.0%. 5. The manufacturing method according to any one of Items 1 to 4, wherein the time for maintaining the temperature at 30°C or higher is 1 to 15 hours. 6. The production method according to any one of Items 1 to 5, wherein the polyvinyl butyral produced by acetalization is aged in the same aqueous phase without being separated from the reaction system.