JPS6329882B2 - - 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 has been suggested that polyvinyl butyral sheets with reduced tack can be obtained. However, this method seems to be 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 say that the quality was sufficient, 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 the present invention is to provide a method for producing polyvinyl butyral, which produces an interlayer film for laminated glass with reduced self-adhesion. An aqueous dispersion containing a phosphoric acid ester surfactant of a condensation product obtained by reacting with butyraldehyde was heated to 30°C in a strongly acidic region.
A method for producing polyvinyl butyral with reduced self-adhesiveness, characterized by raising the temperature to a temperature of 30°C or higher and aging it at a temperature of 30°C or higher. As for the above acid catalyst, acids known to have the effect of condensing polyvinyl alcohol and butyraldehyde can be used as appropriate. Can be mentioned. The amount of acid catalyst used is such that the concentration at the end of the reaction is between 0.5 and 5.
The amount is preferably % by weight. The required amount of the catalyst may be added at once, but in order to precipitate fine polyvinyl butyral, it is preferable to add the catalyst in portions at an appropriate number of 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 rest after precipitation. In addition, the average degree of polymerization of the polyvinyl fluorol used is preferably 800 to 3000, and the degree of saponification is preferably 95 mol% or more, particularly preferably 98 mol% or more, in order to obtain polyvinyl butyral with good transparency. It is. 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 15% by weight. The amount of butyraldehyde used to condense with the polyvinyl alcohol is determined appropriately depending on the degree of butyralization of the target polyvinyl butyral.
When polyvinyl butyral is used as an interlayer film for laminated glass, it is desirable that the degree of butyralization is 60 to 75 mol%. To achieve this, it is recommended to add 49 to 74 parts by weight of butyraldehyde to 100 parts by weight of polyvinyl alcohol. suitable. Examples of the phosphate surfactant in the present invention include alkyl phosphate esters and salts thereof, polyoxyethylene alkyl ether phosphates and salts thereof, polyoxyethylene alkyl phenol ether phosphates and salts thereof, etc. As the salts of each of the esters, sodium salts, potassium salts, alkanolamine salts, etc. are used as appropriate. The structural formula of these surfactants is represented by the following formula (1), for example. (m and n represent integers from 0 to 15, M is hydrogen,
Represents Na or K. When m=0, R ₁ represents an alkoxy group having 4 to 30 carbon atoms, and when m≠0, it represents a hydrocarbon group having 4 to 30 carbon atoms, an alkoxy group having 4 to 30 carbon atoms, and an alkoxy group having 10 to 20 carbon atoms. Represents an alkylphenoxy group or a phenoxy group. R ₂ is n=
When 0, an alkoxy group having 4 to 30 carbon atoms, a hydroxyl group,
-ONa or -OK, and when n≠0, it represents a hydrocarbon group having 4 to 30 carbon atoms, an alkoxy group having 4 to 30 carbon atoms, an alkylphenoxy group or a phenoxy group having 10 to 20 carbon atoms. ) In formula (1), m is 2 to 8, n is 0 or 2 to 8, and R ₁ represents an alkoxy group having 6 to 15 carbon atoms or an alkylphenoxy group having 13 to 16 carbon atoms. , R ₂ is a hydroxyl group when n=0, -
ONa or -OK, when n≠0, carbon number is 6~
A surfactant having 15 alkoxy groups or an alkylphenoxy group having 13 to 16 carbon atoms is preferably used. These surfactants are used alone or in combination, and the amount used is usually such that the concentration in the polyvinyl butyral aqueous dispersion is 0.03 to 1.0% by weight, but within this range It is not limited. In the present invention, any method may be employed to prepare an aqueous dispersion containing a phosphate ester surfactant of a condensation product obtained by condensing polyvinyl alcohol and butyraldehyde. For example, by the precipitation method, when polyvinyl alcohol and butyraldehyde are reacted in the presence of an acid catalyst, the surfactant is added and the surfactant is present in the aqueous dispersion of the condensation product produced by the reaction. Alternatively, the surfactant may be added to an aqueous dispersion of the condensation product produced by the action of the acid catalyst, or the polyvinyl alcohol and butyraldehyde may be reacted using an acid catalyst. The condensation product thus produced may be taken out in the form of powder particles, dispersed again in water, and then the surfactant may be added thereto. In the present invention, in order to make the aqueous dispersion system into a strongly acidic region, conventionally known inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid, and organic acids such as p-toluenesulfonic acid can be used. These acids may be added to the dispersion system, or the polyvinyl butyral may be precipitated or precipitated in a strongly acidic aqueous phase, or the polyvinyl butyral powder may be dispersed once taken out. The strongly acidic region is usually PH2 or less, preferably PH1 or less, although it depends on the temperature of the polyvinyl butyral dispersed phase. Furthermore, the upper limit of the heating temperature of the dispersed phase is not particularly determined, but it is generally set to 90°C or lower, and the time to maintain the temperature at 30°C or higher, including the time for raising and lowering the temperature of the dispersion, is usually 1 to 15 minutes. It is considered as time. In addition, when it is intended 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 4 hours or more, more preferably for 6 hours or more. 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 exceeding 20°C, then the above phosphoric acid ester surfactant is added, and the reaction system is cooled to produce butyral. It is preferable to prepare an aqueous dispersion containing the surfactant by adding an aldehyde and causing a condensation reaction to precipitate polyvinyl butyral at a low temperature such as 20° C. or lower. 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 is particularly limited as long as the temperature does not freeze the reaction system. Although it is not always necessary, a temperature of -6°C or higher is usually employed. After the polyvinyl butyral is precipitated, the acid is usually added to the reaction system, and then the temperature is raised to 30
After the reaction is further progressed and aged at a temperature above 0.degree. C., the acid catalyst is neutralized with a base, and the reaction product is taken out and washed and purified by conventional methods. Conventionally, for the purpose of producing polyvinyl butyral with reduced self-adhesion, after precipitating fine particles of polyvinyl butyral, the temperature of the reaction system is raised to, for example, over 40°C without the presence of the surfactant in the present invention. If the precipitated particles are aged only at a temperature of
When ripening at a low temperature of around 0.degree. C., coarsening of the particles is less likely to occur, but there is a disadvantage that aging is required for an extremely long time. On the other hand, the phosphate ester surfactant used in the present invention has the effect of promoting the butyralization reaction in an aqueous dispersion system at 30°C or higher in a strongly acidic region, while suppressing the coarsening of fine particles. It is recognized that the surfactant is substantially completely desorbed from the polyvinyl butyral during the subsequent neutralization and water washing steps. Therefore, in the present invention, 40
A resin with good transparency and thermal stability can be obtained even if the resin is aged at a temperature exceeding 30°C, and the aging time can be greatly shortened if it is aged at a relatively low temperature of about 30°C. 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 di(2-ethyl butyrate), In addition to general-purpose plasticizers such as triethylene glycol di(2-ethylhexoate), dibutoxydiethylene glycol adipate 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 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, it is self-sustaining at room temperature. Polyvinyl butyral, which provides an interlayer film for laminated glass with reduced adhesion, can be obtained under industrially advantageous temperature and time conditions. 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 Powder distribution 100g of polyvinyl butyral 4, 16, 28,
Sorted through sieves with mesh numbers of 48, 60, 80, and 100,
The weight of the resin remaining on each sieve was determined. 2. Thermal stability A test tube containing polyvinyl butyral was immersed in a heated oil bath, and the thermal stability was determined to be good if the polyvinyl butyral did not change color even after a predetermined period of time at 120°C. 3 Transparency Method A: Add 42 g of triethylene glycol di(2-ethyl butyrate) as a plasticizer to 100 g of polyvinyl butyral, knead with a roll, and then use a hot press to form a plasticized polyvinyl butyral intermediate with a thickness of 10 mm and a smooth surface. A membrane was 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. (Examples 1-3, Comparative Examples 1-3
Method B: 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. (Examples 4 to 6, Comparative Examples 4 to
I followed 6. ) 4 Self-adhesion of interlayer film (T-type peel strength) 42 parts by weight of the specified plasticizer was added to 100 parts by weight of polyvinyl butyral, mixed for 15 minutes in a Raikai machine, and kneaded 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 ³ 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 maintained at a temperature of 20°C. One end of the sample obtained in this way was peeled off from each other, the peeled film was bent in a 90° direction to form a T-shape, and both ends of the peeled film were grabbed with a tensile tester for 20 minutes. T-peel strength was measured at 500 mm/min at a tensile rate 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 2100 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,
As a phosphate ester surfactant

[Formula] 350g dispersed in 3Kg of water was added (surfactant concentration was 0.29% in the final system), and 8.0Kg of butyraldehyde was added dropwise over 30 minutes while stirring at 13℃, resulting in white fine particles. A condensation product of polyvinyl butyral was precipitated. Further, 7.6 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 45° C. at a rate of 25° C./hour, and the temperature was maintained at this temperature for an additional 4 hours for ripening. Neutralize the reaction system by adding sodium hydroxide
The pH was set to 8.5. The aging time in a strongly acidic region at a temperature above 30°C was 5 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%. 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, resin particle size distribution, thermal stability, transparency and self-adhesion of the plasticized polyvinyl butyral interlayer film at each reaction stage were as shown in Table 1. Note that triethylene glycol di(2-ethyl butyrate) was used as the plasticizer. Example 2 In Example 1, as a phosphate ester surfactant A white powder was obtained in the same manner as in Example 1 except that . The degree of butyralization of the obtained resin is
The content was 65.1 mol%, and its physical properties were as shown in Table 1. Example 3 In Example 1, Dai-ichi Kogyo Seiyaku Co., Ltd.'s anionic surfactant "Plysurf AL" was used as the surfactant.
A white powder was obtained in the same manner as in Example 1 except that . The physical properties of the obtained resin were as shown in Table 1. 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. The degree of butyralization was measured after 0 hours, 4 hours, 10 hours, and 12 hours of ripening. Comparative Example 2 Polyvinyl butyral powder was prepared in the same manner as in Example 1 except that 75 g of dodecylbenzenesulfonic acid (0.33% based on the resin) dissolved in 3 kg of water was used as the surfactant. Obtained. Its physical properties were as shown in Table 1. Comparative Example 3 A polyvinyl butyral condensation product in the form of white fine particles was precipitated in the same manner as in Example 1 except that no surfactant was used. Furthermore, 35% concentrated hydrochloric acid
After adding 7.6Kg and reducing the pH of the reaction system to 0.5 or less,
The temperature was increased to 25°C at a rate of °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 1. The degree of butyralization was measured after 0 hours, 8 hours, 16 hours, and 20 hours of ripening.

[Table] Example 4 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 over a period of 30 minutes while stirring at 13° C., a condensation product of polyvinyl butyral in the form of white fine particles was precipitated. Furthermore, after adding 7.6 kg of 35% concentrated hydrochloric acid to bring the pH of the reaction system to 0.5 or less, use it as a surfactant.

[Formula] 350g dispersed in 3Kg of water was added (surfactant concentration was 0.29% in the final system), and the temperature was raised to 45℃ at 25℃/hour.
The mixture was further aged at this temperature for 8 hours. 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 film were as shown in Table 2. Note that triethylene glycol di(2-ethyl butyrate) was used as the plasticizer. Example 5 Everything in Example 4 was repeated except that "Plysurf A207H" (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was used as the surfactant and the aging temperature was kept at 55°C for 5 hours.
A white powder was obtained in the same manner as above. The degree of butyralization of the resulting resin was 65.1 mol%, and its physical properties were as shown in Table 2. Example 6 (Reference Example 1) Add 1 kg of hydrochloric acid with a concentration of 35% 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 2 as Reference Example 1. Next, 10 kg of this polyvinyl butyral was dispersed in 80 kg of water, and a solution of 700 g of Plysurf AL (manufactured by Daiichi Kogyo Seiyaku) as a surfactant dispersed in 4 kg of water was added, and 8 kg of hydrochloric acid with a concentration of 35% was added. The mixture was neutralized, washed with water, and dried by keeping the temperature at ℃ for 4 hours. The properties of the obtained resin were as shown in Table 2. Comparative Example 4 Polyvinyl butyral powder was obtained in the same manner as in Example 4 except that no surfactant was used. Its physical properties were as shown in Table 2. Comparative Example 5 A white powder of polyvinyl butyral was obtained in the same manner as in Example 5 except that no surfactant was added. Its physical properties are shown in Table 2. Comparative Example 6 Polyvinyl butyral powder was obtained in the same manner as in Example 6, except that the resin obtained in Reference Example 1 was post-treated without adding any surfactant. Its physical properties are shown in Table 2.

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Claims (1)

[Scope of Claims] 1. An aqueous dispersion containing a phosphoric acid ester surfactant, which is a condensation product obtained by reacting polyvinyl alcohol and butyraldehyde in the presence of an acid catalyst, is heated at 30°C in a strongly acidic region. Raise the temperature to over 30
A method for producing polyvinyl butyral with reduced self-adhesion, characterized by aging the polyvinyl butyral while maintaining it at a temperature of ℃ or higher. 2. The manufacturing method according to item 1, wherein the phosphate ester surfactant is a compound represented by formula (1). (m and n represent integers from 0 to 15, M is hydrogen,
Represents Na or K. When m=0, R ₁ represents an alkoxy group having 4 to 30 carbon atoms, and when m≠0, it represents a hydrocarbon group having 4 to 30 carbon atoms, an alkoxy group having 4 to 30 carbon atoms, and an alkoxy group having 10 to 20 carbon atoms. Represents an alkylphenoxy group or a phenoxy group. _R2 is m
When = 0, it represents an alkoxy group having 4 to 30 carbon atoms, a hydroxyl group, -ONa or -OK, and when n≠0, it represents a hydrocarbon group having 4 to 30 carbon atoms, an alkoxy group having 4 to 30 carbon atoms, and 10 carbon atoms. ~20 alkylphenoxy or phenoxy groups. ) 3. The manufacturing method according to item 1 or 2, wherein the concentration of the phosphate ester surfactant in the aqueous dispersion is 0.03 to 1.0% by weight. 4. The manufacturing method according to any one of Items 1 to 3, wherein the time for maintaining the temperature at 30°C or higher is 1 to 15 hours. 5 Items 1 to 4 where the pH in the strongly acidic region is 2 or less
1. The manufacturing method according to any one of the above.