JPS6358845B2 - - 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 particularly high transparency and heat resistance stability are 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. For example, the present inventors precipitated fine precipitates of polyvinyl butyral at a relatively low temperature using a precipitation method, and then heated the reaction system and aged it at a high temperature for a long period of time to obtain a plasticized polyvinyl butyral. We have already obtained the knowledge that an interlayer film with reduced self-adhesion can be obtained by adding an agent, but in this case, depending on the aging temperature or time conditions, the precipitated particles may become coarse due to agglomeration, etc. As a result, transparency and heat resistance stability sometimes deteriorated. 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 with reduced tackiness is obtained. However, with this method, the resulting polyvinyl butyral has poor transparency and heat resistance, probably due to the difficulty in sufficiently removing the above amount of organic sulfonic acid from the resin by washing. This was insufficient and it was difficult to use it practically as an interlayer film. 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 raising the temperature of butyral dispersed in an aqueous phase to a temperature of 30°C or higher in a strongly acidic region in the presence of a fluorine-based 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. In the present invention, the fluorine-based surfactant refers to a surfactant that has a fluoroalkyl group and a hydrophilic group, and whose surface tension when an aqueous solution dissolved in water comes into contact with air is significantly lower than the surface tension of water when it comes into contact with air. and preferably has at least one fluoroalkyl group, more preferably has a fluoroalkyl group having 4 or more carbon atoms and 6 or more fluorine atoms, or has one perfluoroalkyl group, Most preferably, it has a perfluoroalkyl group having 6 or more carbon atoms. Suitable examples thereof are shown in Table 1. Table 1 (M indicates H, Li, Na or K) 1 CF ₃ (CF ₂ ) ₆ SO ₃ M 2 CF ₃ (CF ₂ ) ₇ SO ₃ M 3 CF ₃ (CF ₂ ) ₈ SO ₃ M 4 CF ₃ (CF ₂ ) ₁₀ SO ₃ M 5 CF ₃ (CF ₂ ) ₆ COOM 6 CF ₃ (CF ₂ ) ₈ COOM 7 CF ₃ (CF ₂ ) ₁₀ COOM 8 [C ₈ F ₁₇ SO ₂ NHC ₃ H ₆ N(CH ₃ ) ₃ ] ^+- _I 9 [C ₇ F ₁₅ CONHC ₃ H ₆ N(CH ₃ ) ₃ ] ^+- _I 10 C ₈ F ₁₇ SO ₂ N(C ₂ H ₅ ) C ₂ H ₄ OPO( OH) ₂ 11 C ₈ F ₁₇ SO ₂ N (C ₂ H ₅ ) (CH ₂ CH ₂ O) ₁₄ H These fluorine-based surfactants are used alone or in combination, and the amount used is usually , the concentration of polyvinyl butyral dispersion in the final system is 2~
The amount is preferably 2000 ppm, preferably 5 to 200 ppm, but is not limited to this range. It is preferable to add the fluorine-containing 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 the 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 para-toluenesulfonic 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 40° C. or higher is usually 1 to 15 hours, including the time for raising and lowering the temperature of the dispersion, and preferably the time for maintaining the temperature at 40° C. or higher is 3 hours or more. 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, when the pH of the reaction system is 2 or less, a fluorine-based surfactant is added, the temperature of the reaction system is raised, and the reaction is 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 products are removed and washed using a conventional method.
It involves refining. When producing polyvinyl butyral with reduced self-adhesiveness, after precipitating fine particles of polyvinyl butyral, the reaction system is heated to a temperature exceeding 40°C in the absence of a fluorosurfactant. When aged, precipitated particles tend to become coarser due to aggregation, etc., and transparency and furthermore, thermal stability tend to decrease.
On the other hand, when ripening at a low temperature of, for example, around 30°C, coarsening of the particles is less likely to occur, but there is the disadvantage that aging is required for an extremely long time. In contrast, when the fluorine-containing surfactant of the present invention is used, the fluorine-containing surfactant has the effect of suppressing the coarsening of fine particles even when ripened at temperatures exceeding 40°C, and also This is presumed to be because the washing with water was sufficiently effective and no residue remained in the resin, but a resin with good transparency and thermal stability was obtained.
Furthermore, when ripening at a relatively low temperature of around 30°C, the ripening time is greatly shortened. 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 used at industrially advantageous temperatures and temperatures as described above, compared to when the fluorine-based surfactant is not used.
It can be obtained under the condition of time. 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, immediately adjusted to pH 8.6 with a weak alkali, and then purified and dried, and the resulting resin was measured in accordance with JIS K6728 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 of interlayer film 42g of triethylene glycol di-2-ethyl butyrate as a plasticizer was added to 100g of polyvinyl butyral and kneaded with a roll, and then a plasticized polyvinyl butyral interlayer film with a thickness of 10 mm with a smooth surface was formed using a hot press. Obtained. The total light transmittance in the visible region of this interlayer film was measured, and a case where the light transmittance was 85% or more was considered to be a pass. 5 Self-adhesion of interlayer film Add 42 parts by weight of triethylene glycol di2-ethyl butyrate to 100 parts by weight of polyvinyl butyral, mix for 15 minutes in a Raikai machine, knead for 3 minutes at 120°C using a roll, and then mix at 150°C. 40Kg/
Press at cm ² for 3 minutes to create a smooth surface with a thickness of 0.76 mm.
A uniform film was created. This film was cut into a rectangular shape of 3 cm x 10 cm, two sheets were stacked together, and the film was placed in a desiccator kept at a temperature of 20° C. for 48 hours under a load of 6 kg. 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 having 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. When 1.5 kg of concentrated hydrochloric acid (35% concentration) was added to this aqueous solution and 8.0 kg of butyraldehyde was added dropwise over 30 minutes while stirring at 13°C, white fine particles of polyvinyl butyral were precipitated. then
After adding 10.5 kg of 35% acid to bring the pH of the reaction system below 0.5, add 4.5 g/l aqueous solution 1 of sodium perfluorooctyl sulfonate (surfactant concentration in the final system: 37 ppm), and heat at 25°C/hour. After increasing the temperature to 45°C, the temperature was maintained for an additional 4 hours for ripening. Sodium hydroxide was added to this reaction system to neutralize it, and the pH was adjusted to 8.5. The aging time at a temperature above 30°C under a strong acid regime was 5 hours. The obtained resin was washed with water and dried according to a conventional method to obtain a white fine powder of polyvinyl butyral. The degree of butyralization of polyvinyl butyral at this time is
It was 65.1 mol%. On the other hand, the degree of butyralization of the resin obtained after aging for 0 hours, 2 hours, and 6 hours was measured. The degree of butyralization at each reaction stage, the particle size distribution of the resin, the thermal stability, and the transparency of the plasticizer polyvinyl butyral interlayer were as shown in Table 2. Example 2 A white powder of polyvinyl butyral was obtained in the same manner as in Example 1 except that the surfactant No. 10 in Table 1 was used instead of sodium perfluorooctyl sulfonate. The physical properties of the obtained resin were as shown in Table 2. Example 3 A white powder of polyvinyl butyral was obtained in the same manner as in Example 1 except that Florard FC134 manufactured by Sumitomo 3M was used as the fluorine-based surfactant. Its physical properties are shown in Table 2. Comparative Example 1 A white powder of polyvinyl butyral was obtained in the same manner as in Example 1 except that no surfactant was added. Its physical properties are shown in Table 2. Comparative Example 2 Polyvinyl butyral powder was obtained in the same manner as in Example 1 except that a 75 g/l aqueous solution of dodecylbenzenesulfonic acid was used instead of the 4.5 g/l aqueous solution of sodium perfluorooctyl sulfonate. Its physical properties are shown in Table 2. Comparative Example 3 White fine powder polyvinyl butyral was precipitated in the same manner as in Example 1 except that no surfactant was used. Further, 10.5 kg of 35% concentrated hydrochloric acid was added to bring the pH of the reaction system to below 0.5, and the temperature was then raised to 25°C at a rate of 25°C/hour and maintained at this temperature for 20 hours. The degree of butyralization of polyvinyl butyral obtained in the same manner as in Example 1 was 64.8 mol%.
Its physical properties were as shown in Table 2. The degree of butyralization was measured after 0 hours, 8 hours, 16 hours, and 20 hours of ripening. The degree of butyralization, resin particle size distribution, thermal stability, and transparency of the plasticized polyvinyl butyral interlayer film at each reaction stage were as shown in Table 2.

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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 fluorine surfactant. A method for producing polyvinyl butyral with reduced self-adhesion, characterized by maintaining the temperature at 30°C or higher. 2. The manufacturing method according to item 1, wherein the fluorine-based surfactant has at least one fluoroalkyl group. 3. The manufacturing method according to item 2, wherein the fluoroalkyl group has 4 or more carbon atoms and 6 or more fluorine atoms. 4. The manufacturing method according to item 2 or 3, wherein the fluoroalkyl group is a perfluoroalkyl group. 5. The manufacturing method according to item 4, wherein the perfluoroalkyl group has 6 or more carbon atoms. 6. The manufacturing method according to any one of Items 1 to 4, wherein the concentration of the fluorine-containing surfactant in the final system of the dispersion is 2 to 2000 ppm. 7. The manufacturing method according to any one of Items 1 to 5, wherein the time for maintaining the temperature at 30°C or higher is 1 to 15 hours. 8. The production method according to any one of Items 1 to 6, wherein the polyvinyl butyral produced by acetalization is aged in the same aqueous phase without being separated from the reaction system.