JPH0211541B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a laminated glass manufacturing method using a carboxyl group-containing resin obtained by reacting a partially saponified ethylene/vinyl acetate copolymer with an acid as an interlayer film. The present invention provides a method for manufacturing laminated glass with stable quality despite being simple, and is particularly suitable for manufacturing laminated glass having a curved surface. Generally, plasticized polyvinyl butyral film is well known as an interlayer film when manufacturing laminated glass, but the method using this film usually consists of two steps, preliminary adhesion and main adhesion, and also requires a process such as an autoclave. There are drawbacks such as the need for large-scale equipment. On the other hand, it has also been proposed to use a carboxyl modified product of a saponified ethylene/vinyl acetate copolymer or an ethylene/vinyl acetate copolymer added with an organic peroxide as an interlayer film for laminated glass. In order to manufacture laminated glass using these resins as an interlayer film, heating and pressurizing operations in an autoclave are not particularly necessary. Instead, a method of heating in a vacuum frame using, for example, a far-infrared heating furnace or a hot air heating furnace is adopted. It will be done. Therefore, while it has the advantage of not requiring large-scale equipment unlike the case of manufacturing laminated glass using a plasticized polyvinyl butyral film as an interlayer film, the heating method using a furnace has the disadvantage that the temperature distribution is Because of this tendency, situations often occur in which the entire glass surface is not heated uniformly, resulting in a drawback that the incidence of defective laminated glass with bubbles or distortion is extremely high. The present inventors conducted studies on a method for producing laminated glass using a carboxyl modified product of a saponified ethylene/vinyl acetate copolymer as an interlayer film, and finally arrived at the present invention. That is, the present invention uses about 10% of an ethylene/vinyl acetate copolymer containing about 20 to 50% by weight of vinyl acetate.
A film of carboxyl group-containing resin obtained by reacting ~90% partially saponified product with acid is sandwiched between two pieces of glass, placed in a flexible and sealable bag, and the inside of the bag is kept under reduced pressure. While holding the bag
This is a method for producing laminated glass, which is characterized by immersion in a liquid at 80 to 100°C. of the ethylene/vinyl acetate copolymer containing about 20-50% by weight vinyl acetate used in the present invention.
Carboxyl group-containing resin (hereinafter referred to as
HEVA-C (abbreviated as HEVA-C) is a known resin per se, and can be produced by a known method. Specific examples of such resins include DUMILAN C-2280, C-1590, C-1553A, and C-1570A.
(manufactured by Takeda Pharmaceutical Co., Ltd.). Particularly preferred HEVA-C in the present invention is one produced by the method disclosed in Japanese Patent Application No. 58-209611. That is, the content of vinyl acetate is about 20-50% by weight
An ethylene-vinyl acetate copolymer is dissolved in an organic solvent having a boiling point of 50°C or higher, and in this solution, the copolymer is mixed with an alkali alcoholate, and 0.1 to 3 mol of water is added to 1 mol of the alcoholate. This product is produced by saponifying it in the presence of , then adding an unsaturated carboxylic acid or dicarboxylic anhydride to a solution containing this saponified product to cause a reaction, and then contacting this reaction solution with water. Ethylene/vinyl acetate copolymer (hereinafter sometimes abbreviated as EVA) has a vinyl acetate content of about 20 to
Examples include those containing 50% by weight and having a melt index (according to ASTM D-1238) of 0.5 to 500. The EVA can be synthesized by a known method described in, for example, US Pat. No. 2,200,429. EVA like this
Dissolve in an organic solvent with a boiling point of 50°C or higher.
Examples of such organic solvents include aromatic hydrocarbons such as benzene, toluene, O-xylene, m-xylene, ethylbenzene, and propylbenzene, and aliphatic and alicyclic hydrocarbons such as n-hexane and cyclohexane. I can do it. Among these organic solvents, preferred are aromatic hydrocarbons such as xylene and toluene which are azeotropic with water, and solvents having a boiling point of 100° C. or higher. These solvents
It is sufficient to use the amount necessary to dissolve EVA, but in order to make the next reaction proceed smoothly, it is usually preferable to use 150 parts by weight or more of the solvent per 100 parts by weight of EVA. Next, the EVA solution prepared in this manner is subjected to a saponification reaction using an alkali alcoholate catalyst in the presence of a specific amount of water after a lower alcohol is added thereto. Examples of the lower alcohol include methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, sec-butyl alcohol, and tert-butyl alcohol, and methanol is usually used. Although these lower alcohols vary depending on the intended degree of saponification, they are usually used in an amount of about 0.1 to 10 times the mole of vinyl acetate in the raw material EVA. As the alkali alcoholate as a catalyst, alkali metal alcoholates such as sodium methoxide, sodium ethoxide, potassium methoxide, potassium ethoxide, lithium methoxide, and potassium t-butoxide are used. The amount of these alkali alcoholate catalysts used varies depending on the intended degree of saponification, but is usually approximately the same as the number of moles of vinyl acetate present in the raw material EVA.
It is 0.01 to 1 times the mole. This method uses 0.1 to 3
It is characterized by the presence of mol of water; if it is less than 0.1 mol, the saponified product has almost no coloring prevention effect, and if it exceeds 3 mol, the intended degree of saponification cannot be achieved. Excessive alkali catalyst and alcohol are required to produce a saponified product having the following properties, which is not only economically disadvantageous, but also the carboxyl group-containing resin obtained from the saponified product produced under such conditions: When used as a product such as a laminated glass interlayer film, problems arise in terms of quality, such as increased opacity. The saponification reaction of the present invention is carried out under conventional conditions, for example at 40 to 60°C, and when the degree of saponification reaches the intended value, water is added to the reaction system to completely stop the reaction. let In order to obtain the intended degree of saponification, the amounts of lower alcohol and catalyst may be adjusted. Saponification reactions in the presence of water generally require an excess amount of alcohol compared to saponification reactions in the absence of water. In the present invention, the degree of saponification in this step is not particularly limited, but is usually approximately 10 to 90%, preferably 30 to 90%.
A saponified product with a degree of saponification of 70% is produced.
The melt index (MI, g/
10min) is usually 1 to 450. The reaction solution in the above saponification reaction is subsequently subjected to an acid modification reaction using an unsaturated carboxylic acid or an acid anhydride, but prior to this reaction, the saponification reaction solution is heated and used to stop the reaction. It is preferable to carry out a treatment in which water and low-boiling substances produced as by-products in the reaction are distilled off and removed. Particularly when an acid anhydride is used, the presence of water in the reaction system will impede the modification reaction, so it is necessary to substantially remove water. The unsaturated carboxylic acid is reacted by heating in the presence of a radical-forming substance. Here, unsaturated carboxylic acid has the general formula
In CHR′=CRCOOH, R and R′ are hydrogen,
It is represented by an alkyl group, a carboxyl group, or a carboxylic acid ester, and specific examples include monocarboxylic groups such as acrylic acid, methacrylic group, croton group, and itaconic acid, and dicarboxylic acids. The amount of unsaturated carboxylic acid used is at most about 5% by weight, preferably about 5% by weight, based on the saponified product.
It is about 0.2 to 3% by weight. Radical-forming substances are substances that can easily decompose to form radicals at the graft polymerization temperature, such as organic peroxides such as benzoyl peroxide, lauroyl peroxide, dicumyl peroxide, α, α' Examples include nitrogen-containing compounds such as -azobisisobutyronitrile. These radical-forming substances are present in an amount of about 0.05 to 3% by weight, preferably about
It is used in an amount of 0.1-1% by weight. The heating temperature cannot be determined unconditionally depending on the type of unsaturated carboxylic acid or solvent used, but it is approximately 50 to 150℃.
℃, and the heating time is about 0.1 to 5 hours. The acid anhydride is reacted by adding the acid anhydride to the heat-treated reaction solution and heating the mixture at about 50 to 150°C for about 0.1 to 5 hours. The acid anhydride used here has the general formula

[Formula] where R'' represents, for example, a divalent aromatic or aliphatic residue, specifically, for example, maleic anhydride, succinic anhydride, glutaric anhydride, phthalic anhydride, itaconic anhydride. Examples include acids, trimellitic anhydride, hemicic anhydride, and the like.
In the above reaction, the acid anhydride is contained in the saponified product.
Ring-opened by OH group

It is estimated that [Formula]. The amount of acid anhydride is at least about 2 mol% or more, preferably about 5 mol% of the vinyl alcohol units contained in the saponified product.
This is the amount required to react (esterify) ~50 mol%. The reaction solution obtained by such acid modification reaction is then catalyzed with water. Examples of the method of catalyzing with water include a method of injecting water into the reaction solution or a method of injecting the reaction solution into water. In any of these methods, it is preferable that the reaction solution and water be brought into sufficient contact with each other by injection and mixing under vigorous stirring. Alternatively, a method may be adopted in which a column is used to bring about countercurrent contact. There is no particular limit to the amount of water, but in the case of a batch method, it is usually
Approximately 200 to 1000 (preferably 300 to 600) parts by weight of water are used. Although room temperature is sufficient for the contact temperature, the contact is usually carried out in a heated state (80 to 120°C). The reaction solution that has been brought into sufficient contact with water can be heated, for example, to distill off the solvent present in the reaction solution to some extent (if a solvent that is azeotropic with water is used, it will be distilled off together with water). (d), the reaction solution gradually becomes emulsified. The amount of solvent is 10 to 100 (preferably 20 to 100 parts by weight) per 100 parts by weight of solid content in the reaction solution.
80) The best emulsified state can be maintained by adjusting the parts by weight. Alternatively, a method may be adopted in which the solvent is distilled off from the reaction solution, the solution is brought into contact with water, and then emulsified. By cooling the emulsified system while stirring vigorously (to a temperature lower than the melting point of 50 to 100° C. of the carboxyl modified product produced by the acid modification reaction), HEVA-C is precipitated in the form of granules. In this way, it was precipitated in granular form.
HEVA-C can be collected by separating it using a known separation means such as filtration or centrifugation, and then drying it using a known drying means such as vacuum drying or fluidized drying. In the present invention, it usually has an acid value of 1 to 50 mgKOH/g.
HEVA-C can be used. In the present invention, the HEVA-C described above is used as a membrane (film or sheet), but such a film or sheet is, for example, T-
It can be manufactured using conventional means such as a die extruder. That is, the molding is carried out by extrusion into a sheet at a molding temperature that does not substantially cause decomposition, preferably by passing it through a take-up roll with an embossed pattern. Formation of an arbitrary embossed pattern is effective for preventing blocking of the sheet and for degassing during the manufacturing process of laminated glass. Although the thickness of the sheet is not particularly limited, it is generally about 0.1 to 1 mm, preferably about 200 to 500 μm. In addition, if light resistance is particularly required,
It is preferable to add a light stabilizer to HEVA-C, such as 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-
Methoxybenzophenone, 2-hydroxy-4-
Methoxy-2'-carboxybenzophenone, 2-
Benzophenones such as hydroxy-4-n-octoxybenzophenone, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-5-methylphenyl) Benzotriazoles such as benzotriazole, 2-(2'-hydroxy-5-tertiary octylphenyl)benzotriazole, salicylic acid esters such as phenyl salicylate and p-octylphenyl salicylate, nickel lead salts type, hindered amine type, etc. are used as light stabilizers. When these light stabilizers are used in combination with antioxidants such as hindered phenols and phosphites, a synergistic effect may be expected. Further, other resins and inorganic fillers may be added within a range that does not impair the performance as a laminated glass interlayer film. To manufacture laminated glass by the method of the present invention, first the HEVA-C film is sandwiched between two pieces of glass. In the case of curved glass, a curved film that follows the curved surface may be used. The membrane used is approximately the same size as the glass normally used. If necessary, it may be fixed using a clamp or the like. Next, this glass laminate is inserted into a flexible and sealable bag through its opening. Close the opening and reduce the pressure inside the bag using the vacuum line from the degassing port. The degree of pressure reduction depends on the thickness and size of the laminated glass, but usually
It should be 100 Torr or less, preferably 30 Torr or less.
The bag, whose interior has been reduced in pressure in this way, is immersed in a liquid heated to 80 to 100°C while maintaining the reduced pressure. The immersion time depends on the type of HEVA-C film, the thickness of the glass, etc., but is usually 10 to 15 minutes. The liquid heated to 80 to 100°C is most preferably hot water or boiling water at 80 to 100°C. In some cases, 50-60 min before immersion in the heated liquid.
Pre-soaking may be performed in which the material is immersed in a liquid at .degree. After heating, the bag may be taken out of the liquid and allowed to cool, or may be pre-cooled by immersing it in cold water. In this way, laminated glass can be manufactured. The material of the bag includes, for example, neoprene rubber, synthetic rubber such as butyl rubber, Al/nylon,
Al/PET, polypropylene/6-nylon,
Plastic laminate films such as PP/polyester may be mentioned. Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 Melt index (g/10 min; ASTM1238
-according to 65T. (same below) 30, vinyl acetate content 33
2 kg of EVA (wt%) was added and heated until the internal temperature reached 40 to 50°C to form a homogeneous solution. To this solution, 194 g of pre-prepared methanol, 69 g of 24% sodium methoxide-methanol solution and 7.2 g of water.
was added and reacted for 60 minutes at 45 to 55°C with stirring, and then water 27 was added to completely stop the saponification reaction. The degree of saponification of the saponified product obtained was approximately 50%. Next, under a nitrogen gas stream, the internal temperature was raised to 120°C while distilling off low-boiling substances.
Add 20g of acrylic acid and 2g of benzoyl peroxide,
A graft reaction was carried out at 120°C for 30 minutes with stirring to denature the saponified product with acid. Subsequently, this viscous reaction solution was transferred under nitrogen gas pressure to a 20 Henschel mixer equipped with a condenser, nitrogen gas inlet tube, and thermometer, and the internal temperature was lowered to 100°C, and then heated to 80°C.
12 liters of warm water was added to the mixture. This mixture was heated with stirring at a rotation speed of 510 rpm, and the xylene remaining in the system was distilled off by azeotropic distillation with water until the amount of xylene remaining in the system became 60 parts by weight based on 100 parts by weight of solid content. At the end of xylene distillation, the system became emulsified. When this emulsion was cooled while stirring at 510 rpm while pouring cold water into the jacket of a Henschel mixer, granules with an average particle size of 2 mm were obtained.
This was centrifuged and further dried under vacuum at 50° C. for 4 hours to obtain 1835 g of a carboxyl group-containing resin having the following physical properties. Vinyl alcohol content 7.0 mol% Acrylic acid content 0.3% by weight Sodium acetate content 0.1% by weight Melt index (g/10min) 20 Degree of coloration No coloration Added 0.5 parts of Tinuvin 326 to the resin thus produced.
(Ciba Geigy product) to create pellets, extrude the pellets into a sheet using a T-die extruder at a resin temperature of 160°C, and use an embossed pattern take-up roll to create embossed patterns on both sides of the sheet. 0.4mm thick HEVA-
A film (sheet) of C was prepared. The sheet thus obtained was sandwiched between a pair of circular curved glasses made of float glass with a thickness of 3 mm and a diameter of 30 cm.
- The bag was placed in a bag made from a nylon laminate, the opening of the bag was heat-sealed, and the bag was evacuated at room temperature using a Shimadzu model KD-300 vacuum pump through the degassing port.
With the vacuum still open, this vacuum bag was immersed in warm water at 60°C for 3 minutes, and then immersed in boiling water for 15 minutes to heat it. Remove the bag from the boiling water and
After cooling by immersing in hot water at 50°C for 3 minutes, the operation of the vacuum pump was stopped, the vacuum bag was opened, and the curved glass was taken out. In this way, a curved laminated glass that was colorless, transparent, and had no residual bubbles and an adhesive layer thickness of about 0.4 mm was obtained. In addition, since a transparent vacuum bag was used, the internal state of the laminated glass could be sufficiently observed during manufacture. First, soak this curved laminated glass in warm water at 65°C for 30 minutes.
A heat resistance test was conducted in which the glass was immersed in boiling water for 2 hours in an almost vertical position, but no damage such as clouding or peeling of the laminated glass occurred. Example 2 In a stainless steel reactor equipped with a stirrer, a condenser, a thermometer, and a nitrogen gas inlet tube, industrial xylene 5, melt index 30 synthesized by high-pressure polymerization, and a vinyl acetate content of 33% by weight were added.
2 kg of EVA was added and heated until the internal temperature reached 40 to 50°C to form a homogeneous solution. To this solution, 904 g of methanol prepared in advance, 103 g of 24% sodium methoxide-methanol solution and 6.6 g of water were added, and after reacting for 60 minutes at 45-55°C with stirring, 40 g of methanol was added.
g was added to completely stop the saponification reaction. The degree of saponification of the saponified product obtained in this way is approximately 70%.
It was hot. Next, the internal temperature was raised to 125° C. under a nitrogen gas stream while distilling off low-boiling substances and water. After distilling 1 kg of industrial xylene at this temperature, the supply of nitrogen gas was stopped and the reactor was cooled until the internal temperature reached 100°C. Hexahydrophthalic anhydride
Add 106g to the reactor and heat at 100-105℃ for 60 minutes under stirring.
The reaction was carried out for minutes. This reaction solution was transferred to a 20° Henschel mixer equipped with a condenser, nitrogen gas inlet tube, and thermometer under nitrogen gas pressure, and heated to 80°C.
12 liters of warm water was added to the mixture. This mixture was heated with stirring at a rotational speed of 510 rpm, and xylene was distilled off by azeotropic distillation with water until the amount of xylene remaining in the system became 70 parts by weight based on 100 parts by weight of solid content. The system was emulsified by the time the xylene had finished distilling off. This emulsion was cooled while stirring at 510 rpm while adding water to the jacket of a Henschel mixer to obtain granules with an average particle size of 2 mm. This was centrifuged, further dried under vacuum at 50℃ for 4 hours, and HEVA-C1920g having the following physical properties was obtained.
I got it. Vinyl alcohol content 7.0 mol% Acid content 1.9 mol% Sodium acetate content 0.1 wt% Melt index (g/10min) 15 Coloration degree No coloration Added 0.5 parts by weight of Tinuvin 326 (Ciba・Geigy Co. product) was melt-blended to create pellets, and a double-sided embossed sheet with a thickness of 0.4 mm was created in the same manner as in Example 1 using an extruder. A curved laminated glass was produced using this embossed sheet in the same manner as in Example 1.
A transparent laminated glass without residual bubbles was obtained. When a heat resistance test was conducted in the same manner as in Example 1, no damage occurred to the laminated glass.

Claims (1)

[Claims] 1 A film of carboxyl group-containing resin obtained by reacting an acid with a 10-90% partially saponified ethylene/vinyl acetate copolymer containing 20-50% by weight of vinyl acetate is placed between two pieces of glass. and heat the bag to 80 to 100℃ while maintaining a vacuum inside the bag.
A method for manufacturing laminated glass, characterized by immersion in a liquid.