JPS6146425B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an interlayer film for laminated glass with improved self-adhesion. It is widely known that a film made of plasticized polyvinyl butyral, which is obtained by adding a plasticizer to polyvinyl butyral, is used as an interlayer film for bonding laminated glass. The plasticized polyvinyl butyral film has excellent adhesive strength, light stability, transparency, and low-temperature flexibility, and is widely used today as an interlayer film for laminated glass for automobiles, aircraft, and architecture. However, the conventional interlayer film for laminated glass is
Due to the strong adhesiveness of the membrane surface, there is a problem that the membranes stick together (self-adhesion) when rolled up after film formation.To prevent such sticking, the membrane surface is embossed, and in addition, anti-adhesive agents such as sodium bicarbonate are used to prevent such adhesion. The agent is being sprayed.
Therefore, when bonding a conventional interlayer film and glass, a washing process to remove the anti-blocking agent and a washing process are required beforehand.
This method has the disadvantage of requiring a subsequent drying process to adjust the moisture content of the interlayer film. In view of the above-mentioned current situation, the present inventors have repeatedly conducted experiments and research to improve the self-adhesion of interlayer films, and have discovered the infrared absorption spectrum of polyvinyl butyral and the self-adhesion of interlayer films made by adding a plasticizer to polyvinyl butyral. The present invention was completed by discovering the relationship between An interlayer film for laminated glass made of polyvinyl butyral to which a plasticizer is added satisfies formula (1) ((1) Y≧−3X+486), where Y (cm ⁻¹ ) is the half width of Y (cm −1 ). In the present invention, the half width is defined as follows. First, in the infrared absorption spectrum of polyvinyl butyral, where the vertical axis is the transmittance (%) and the horizontal axis is the wave number (cm ^-1 ), as shown in Figure 1, the wave number is 3900 cm ^-1.
Connect the positions showing the transmittance at 2300 cm ^-1 and use this as the reference line. Next, calculate the distance from the horizontal axis (transmittance 0%) to the reference line through peak A of the absorption spectrum of hydroxyl groups between wave numbers 3900 cm ^-1 and 2300 cm ^-1 .
When I ₀ is the distance to peak A of the absorption spectrum of the hydroxyl group, I ₁ is the transmittance that gives the half-width, that is, the distance from the horizontal axis I _A is the geometric mean of I ₀ and I ₁ , I _A
= √ ₀ × ₁ , and further, the half width Y is determined from I _A as shown in FIG. The present inventors have discovered that even if polyvinyl butyral has the same degree of butyralization, the absorption band of the hydroxyl group in its infrared absorption spectrum differs slightly. That is, the half width of polyvinyl butyral that provides an interlayer film with improved self-adhesion is always larger than that of polyvinyl butyral that provides an interlayer film with high self-adhesion even if the degree of butylation is the same. Although the reason is not fully clear, it is presumed as follows. Generally, it is thought that increasing the rigidity of polyvinyl butyral will reduce its self-adhesion, but on the other hand, it is impossible to completely butyralize polyvinyl alcohol in the butyralization reaction, and its structure consists of a vinyl butyral group, a vinyl alcohol group, and a vinyl acetyl group. If the arrangement of these groups differs, the physical properties of the polyvinyl butyral will differ, and it is expected that, for example, the self-adhesiveness of the resulting interlayer film will change. In other words, polyvinyl butyral, in which the hydroxyl groups of vinyl alcohol groups are arranged in a chain, has stronger association through hydrogen bonds than polyvinyl butyral, in which the hydroxyl groups are arranged irregularly, resulting in increased rigidity and an interlayer film with low self-adhesion. It is thought that it will be possible. However, the hydroxyl group absorption band in the infrared absorption spectrum of polyvinyl butyral is on the lower energy side, that is, on the lower wave number side, because there is a part where the association by hydrogen bonds is stronger compared to that of polyvinyl butyral, where the arrangement of hydroxyl groups is irregular. As it expands, the half-width of hydroxyl group absorption becomes large. The present inventors completed the present invention by pursuing the relationship between the half width Y of polyvinyl butyral, the degree of butyralization X, and the self-adhesion of the interlayer film. Polyvinyl butyral that satisfies the above formula (1) can be produced by, for example, a precipitation method, in which butyraldehyde is added to polyvinyl alcohol to obtain a precipitate at a relatively low temperature, and then the reaction system is heated to a high temperature for a long period of time. After ripening, it is obtained by neutralizing, washing with water, and drying according to a conventional method. The degree of butyralization of the polyvinyl butyral used in the present invention is 60 to 75 mol% because if it is too low, it will have poor compatibility with plasticizers, and if it is too high, various physical properties such as penetration resistance will decrease when laminated glass is made. It is desirable that there be. For measuring the degree of butyralization, known methods such as the hydroxylamine hydrochloride method are appropriately employed. Furthermore, the plasticizer used in the present invention may be any one that is generally used as a plasticizer for polyvinyl butyral, such as triethylene glycol di-2-ethylbutyrate, triethylene glycol-di-2-ethylhexoate, etc. is 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 of the laminated glass will decrease, 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, and when used as an interlayer film for laminated glass. This is because it has an adverse effect on the transparency and adhesiveness of the film. When producing the polyvinyl butyral used in the present invention, it is preferable that the average degree of polymerization of the raw material polyvinyl alcohol is 800 to 3000, and the degree of saponification is 95 mol% or more in order to obtain polyvinyl butyral with good transparency. is preferred. In the interlayer film for laminated glass of the present invention, a plasticizer is added to polyvinyl butyral whose half-width Y (cm ^-1 ) of hydroxyl absorption in the infrared absorption spectrum is in the relationship of Y≧-3X+486 with the degree of butyralization X (mol%). Since it is added, self-adhesion is low, so there is no need to spray an anti-tack agent, and subsequent washing and drying steps are not necessary. Examples of the present invention are shown below. The self-adhesion force was measured as follows. Add a specified amount of plasticizer to polyvinyl butyral resin, mix for 15 minutes using a Laikai machine, knead for 15 minutes at 120℃ using a 6-inch roll, and press for 15 minutes at 120℃ to obtain a smooth surface with a thickness of approximately 0.8mm. to create a uniform film. This film was cut into a rectangular shape of 3 cm x 10 cm, and the two films were stacked together and left in a desiccator at a temperature of 20° C. for 48 hours under a load of 4 kg. The T-peel force of this sample was measured using a tensile tester at a speed of 500 mm/min, and this was taken as the self-adhesion force. Example 1 100 g of polyvinyl alcohol with a degree of saponification of 98.0 mol% and a degree of polymerization of 2100 was dissolved in 880 g of distilled water, and 57 g of concentrated hydrochloric acid was added.
g and kept at 14.4℃, butyraldehyde 49g
was added dropwise for 15 minutes, and 10 minutes after the dropwise addition, a polyvinyl butyral precipitate was obtained. By increasing the temperature of this reaction system
After keeping the temperature at 60°C for 4 hours, the temperature was lowered and neutralized with baking soda. Wash the obtained polyvinyl butyral with water,
The degree of butyralization after drying was determined to be 619 mol%. Dissolve 1 g of this polyvinyl butyral in a mixed solvent of 10 c.c. of butanol and 15 c.c. of ethanol.
After casting on a mirror surface, dry at 60℃ in a vacuum dryer for 3
After drying for several hours, a polyvinyl butyral film was obtained. The infrared absorption spectrum of this film was measured using an EPI-G ₃ diffraction grating infrared spectrophotometer manufactured by Hitachi, Ltd. The half-width Y of hydroxyl absorption obtained from this spectrum chart was 331 cm ^-1 , which satisfied formula (1). To 100 g of this polyvinyl butyral was added 42 g of triethylene glycol di-2-ethyl butyrate as a plasticizer, and a film was prepared according to the sample preparation and measurement conditions for self-adhesion measurement described above, and the T-peel force was measured. The peeling force at this time was 0.25Kg/as shown in Table 1.
It was cm. Examples 2 to 6 Polyvinyl alcohol aqueous solution containing hydrochloric acid catalyst
After keeping the temperature at 14.4°C and adding butyraldehyde to precipitate, the reaction system was heated and kept at high temperature for a long time, followed by neutralization, washing with water, and drying according to conventional methods to obtain a white powder of polyvinyl butyral. Furthermore, in the same manner as in Example 1, the infrared absorption spectrum of this polyvinyl butyral was measured to determine the half width Y of hydroxyl group absorption. The T-type peeling force of the film was measured. These values, the degree of polymerization of polyvinyl alcohol, the degree of saponification, and the aging temperature during braralization,
Table 1 shows the aging time, the degree of butyralization X of polyvinyl butyral, and the amount of plasticizer added. Comparative Examples 1 to 6 Polyvinyl alcohol aqueous solution containing hydrochloric acid catalyst
After keeping the temperature at 14.4℃ and adding butyraldehyde to precipitate, the reaction system was heated to 20 to 40℃ for 2 to 10 minutes.
The mixture was kept for a certain period of time, and then neutralized, washed with water, and dried according to a conventional method to obtain a white powder of polyvinyl butyral. Furthermore, in the same manner as in Example 1, the infrared absorption spectrum of this polyvinyl butyral was measured to determine the half-width Y of hydroxyl group absorption, while the same plasticizer as in Example 1 was added to this polyvinyl butyral and a film was formed by the method described above. The T-peel force was then measured. Table 1 shows these values, the degree of polymerization of polyvinyl alcohol, the degree of saponification, the degree of butyralization of polyvinyl butyral, the amount of plasticizer added, etc.

【table】

【table】 [Brief explanation of the drawing]

FIG. 1 is a chart showing an example of the infrared absorption spectrum of polyvinyl butyral used in the interlayer film of the present invention. A...Peak of absorption spectrum of hydroxyl group.

Claims (1)

[Scope of Claims] 1 When the degree of butyralization is expressed as X (mol %), the vertical axis is the transmittance, and the horizontal axis is the half-width of hydroxyl absorption in the infrared absorption spectrum Y (cm ^-1 ), An interlayer film for laminated glass made by adding a plasticizer to polyvinyl butyral that satisfies formula (1). (1) Y≧−3X+486 2 The interlayer film according to item 1, wherein the degree of butyralization is 60 mol% to 75 mol%. 3 The amount of plasticizer added is polyvinyl butyral 100
The interlayer film according to item 1 or 2, wherein the amount is 30 to 60 parts by weight.