JPH0253382B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to laminated glass used for automobile windshields, building window glasses, etc. Polyvinyl butyral resin is most commonly used for the intermediate layer of conventional laminated glass. However, this resin is thermoplastic and has several problems when used as a laminated glass. (1) After lamination, the glass plates may shift due to heat,
Generation of air bubbles may be observed. (2) Impact rupture performance is affected by temperature, and penetration resistance drops significantly especially in the temperature range above room temperature. (3) Polyvinyl butyral films are coated with baking soda to prevent adhesion between films. (4) It is necessary to remove moisture from the surface, wash it with water, and dry it before use. (4) It is necessary to adjust the moisture content to obtain the appropriate adhesion to the glass. There is a problem with this. The object of the present invention is to provide a new laminated glass that improves these drawbacks. As a result of examining various resin materials to achieve this objective, the present invention was completed by achieving the objective by using a resin composition composed of an ethylene-vinyl acetate copolymer. That is, the present invention provides a photocurable resin composition comprising an ethylene-vinyl acetate copolymer having a vinyl acetate content of 15 to 50% by weight, and a photosensitizer in an amount of 5% by weight or less based on the copolymer. By interposing it between glass plates and integrating it with the glass plate, heating it above the melting point of the resin and irradiating it with light,
A laminated glass with a hardened resin layer,
This is a laminated glass that withstands impact tests according to JISR3205, 3211 and 3212 and has a haze value of 1.0 or less. The intermediate layer material of the present invention is a curable resin that crosslinks and hardens when exposed to light, and provides a laminated glass in which the ethylene-vinyl acetate resin intermediate layer is made transparent by photocrosslinking and hardening upon heating. Originally, ethylene-vinyl acetate resins have different transparency and physical properties depending on their vinyl acetate content. For example, glass with a vinyl acetate content of 40% has relatively good transparency, but has problems with tensile properties, has low breaking strength, and has an elongation of over 1000%, making it suitable for use as an intermediate layer in laminated glass. not suitable for Also, materials with a content of about 15% vinyl acetate have poor transparency and are unsuitable as laminated glass materials where transparency is required. Furthermore, since ethylene-vinyl acetate resin is originally a thermoplastic resin, it is easily affected by temperature, and has the disadvantage that, like polyvinyl butyral resins, its physical properties deteriorate particularly at high temperatures. In this way, ethylene
Although the transparency of vinyl acetate resin varies depending on the vinyl acetate content, clouding is still a problem compared to the transparency of glass. As a result of further research, we found that by photo-crosslinking and curing the ethylene-vinyl acetate copolymer when heated in the presence of a photosensitizer, the cloudiness disappeared, extremely high transparency was obtained, and physical properties were also improved. It has been found that this material is suitable as an intermediate layer material for laminated glass, leading to the completion of the present invention. The ethylene-vinyl acetate copolymer used for the purpose of the present invention preferably has a vinyl acetate content of 15 to 50% by weight, particularly preferably 19 to 40% by weight. When vinyl acetate exceeds 50% by weight, transparency is good, but good penetration resistance cannot be obtained even if the acrylic monomer described below is added. On the other hand, if it is less than 15% by weight, it will be difficult to improve transparency even if crosslinked at high temperatures. The photosensitizer to be added to the ethylene-vinyl acetate copolymer of the present invention may be any one that directly or indirectly generates radicals when irradiated with light, such as benzoin, benzophenone, benzoin methyl ether, benzoin Ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, dibenzyl, 5-nitroacenaphthene, hexachlorocyclopentadiene, paranitrodiphenyl, paranitroaniline, 2,4,6-trinitroaniline, 1,2-
Examples include benzanthraquinone and 3-methyl-1,3-diaza-1,9-benzanthrone. At least one of these photosensitizers is added in an amount of 5 parts by weight or less per 100 parts by weight of the ethylene-vinyl acetate copolymer. In addition, in the present invention, ethylene-vinyl acetate copolymer is used as a curing aid in the photocurable resin composition.
Up to 50% by weight of an acryloxy group- or methacryloxy group-containing compound selected from derivatives of acrylic acid and methacrylic acid can be added. These additions contribute to improving the degree of crosslinking and crosslinking speed during photocrosslinking, and also contribute to improving physical properties.
Esters and amides are the most common derivatives of acrylic acid and methacrylic acid, and the alcohol residues in esters include alkyl groups such as methyl, ethyl, dodecyl, stearyl, and lauryl, as well as cyclohexyl. group, tetrahydrofurfuryl group, aminoethyl group, 2-hydroethyl group, 3-hydroxypropyl group, 3-
Examples include chloro-2-hydroxypropyl group. Also, esters with polyfunctional alcohols such as ethylene glycol, triethylene glycol, polyethylene glycol, trimethylolpropane, and pentaerythritol can be used similarly. Moreover, diacetone acrylamide is a typical example of the amide. Furthermore, in order to improve the adhesion between the intermediate layer and the glass, 5% by weight of the ethylene-vinyl acetate copolymer was added to the intermediate layer material as a known silane coupling agent.
It can be added in the following proportions. Silane coupling agents include γ-chloropropyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyl-tris(β-methoxy)silane, γ-methacryloxypropyltrimethoxysilane, β-(3,4-ethoxysilane) cyclohexyl)ethyl-trimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ- Aminopropyltrimethoxysilane and the like can be mentioned. Furthermore, in order to improve storage stability, a polymerization inhibitor such as hydroquinone, hydroquinone monomethyl ether, p-benzoquinone, methylhydroquinone, etc. may be added in a proportion of 5% by weight or less. In addition to these, small amounts of colorants, ultraviolet absorbers, stabilizers, anti-discoloration agents, etc. can also be optionally added depending on the purpose. The resin composition of the present invention having the above composition is formed into a sheet using an extruder, a calendar, an inflation machine, a hot press, etc., and is sandwiched between two glass plates in the same process as the polyvinyl butyral film. Unlike polyvinyl butyral films, there is no need to remove the baking soda, wash it with water, or dry it to prevent blocking. Furthermore, in the case of a polyvinyl butyral film, moisture adjustment is performed to maintain the adhesive force with glass at an appropriate level, but in the present invention, this is not necessary and the process can be greatly simplified. Furthermore, the present invention has excellent thermal stability, allowing a wide range of temperatures and methods to be used in the sheet processing or clamping process with glass, and combined with the adoption of a continuous method, significantly increases production efficiency. It is something. After the intermediate layer is clamped between two glass plates as described above, it may be placed in a rubber bag or the like and then heated and depressurized, or it may be passed between several sets of rubber rolls and gradually heated and pressurized. It depends on how you strengthen it,
The key is to expel the air present between the glass and the intermediate layer to uniformly bond the film and glass. Here, the laminated glass plate, in which the intermediate layer is sandwiched between two glass plates and integrated, is irradiated with light. Many types of light sources that emit light in the ultraviolet to visible range can be used as photocuring (crosslinking) light sources, such as SP.
Ultra-high pressure, high pressure, as disclosed in UV Curing, Science and Technology, Technology Marketing Corporation (1980), edited by
Low-pressure mercury lamps, chemical lamps, xenon lamps,
Examples include halogen lamps, Mercury xenon, carbon arc lamps, sunlight, incandescent lamps, and laser lights. Although the irradiation time cannot be determined unconditionally depending on the type of lamp and the intensity of the light source, it is approximately several tens of seconds to several tens of minutes. In addition, in order to perform heating at this time, the heat rays emitted from the above light source may be used partially or completely, and other methods such as air, electric heat, dielectric, hot water,
Known heat sources such as steam can be used indirectly or directly. In short, any means can be selected as long as the intermediate layer can be heated to a predetermined temperature or higher when irradiated with light. Moreover, this heating may be performed simultaneously with the light irradiation or prior to the light irradiation. It is necessary to heat the resin at a temperature higher than the melting point of the resin; heating at a temperature lower than the melting point is not preferable because the laminated glass will not have sufficient transparency. Since the laminated glass of the present invention strongly adheres to the glass plate after the intermediate layer is hardened, there is no possibility that bubbles will be generated or the glass plate will shift due to heat or the like. Further, when the glass is broken by impact, no separation occurs between the intermediate layer and the glass, and glass fragments can be prevented from scattering. Next, the present invention will be explained with reference to Examples. Example 1 (1) Blending Compositions A to C shown in the table below were blended in a roll mill heated to 80 to 90°C.

[Table] (2) Preparation of laminated glass Compositions A to C were sandwiched between polyester films in a press at 100°C to produce a 0.4 mm sheet. Then peel off the polyester film and
It was sandwiched between two pieces of 3 mm thick float glass that had been previously washed and dried, placed in a rubber bag, and degassed under vacuum at a temperature of 100°C for 5 minutes. In this state, the laminate becomes completely bubble-free. This was immediately irradiated with ultraviolet light using a 4KW UV irradiation device at a distance of 15 cm for 30 seconds on each side for a total of 1 minute. A laminated glass was also prepared from composition C, which was heated to 160° C. and then irradiated with ultraviolet rays in the same manner. (3) Physical property test (a) An impact test was conducted in accordance with JISR3025 by freely dropping a steel ball with a smooth surface weighing 225 g from a height of 5 m onto the center of the laminated glass. In all cases, the steel balls did not penetrate, no cracks were observed in the intermediate layer, and almost no glass was scattered. (b) Transparency Test The haze values of the laminated glasses of Compositions A to C and C' were measured using an integral turbidity meter TC-SP manufactured by Tokyo Denshoku Co., Ltd. For comparison, measurements were also made on a laminated glass produced by the same method using only ethylene-vinyl acetate.

[Table] All of the products of the present invention have significantly reduced haze values. Example 2 (1) Compounding The formulation was carried out in the same manner as in Example 1 according to the table below.

【table】

[Table] (2) Production of laminated glass A laminated glass was produced in the same manner as in Example 1. However, the intermediate layer sheet used was 1.0 mm thick. (3) Physical properties test (a) Impact test An impact test was conducted in accordance with JIS3211 and 3212 by freely dropping a smooth-surfaced steel ball weighing 2.3 kg onto the center of the laminated glass from a height of 4 m.
As a result, the steel ball did not penetrate in any case, and there was almost no glass scattering. (b) Measurement of physical properties Each material sandwiched between polyester films was pressed using a press heated to 100°C to produce a sheet with a thickness of about 1 mm. Immediately after being removed from the press at 100°C while sandwiched between polyester films, 4KW UV irradiation was applied to both sides at a distance of 15 cm for a total of 1 minute to cure the glass, as in the case of laminated glass. After peeling off the polyester film, punch it out with a DIN No. 3 blade and autograph (tensile tester manufactured by Shimadzu Corporation).
The tensile properties were measured at a crosshead speed of 200 mm/min. The results are shown in the table below.

[Table] From the table above, it can be seen that the addition of methacrylic acid ester etc. improves the physical properties of the intermediate layer.

Claims (1)

[Scope of Claims] 1. A photocurable product prepared by blending an ethylene-vinyl acetate copolymer with a vinyl acetate content of 15 to 50% by weight and a photosensitizer in an amount of 5% by weight or less based on the copolymer. A laminated glass in which a resin composition is interposed between glass plates and integrated with the glass plates, and the resin layer is cured by heating the resin composition to a temperature higher than the melting point of the resin and irradiating it with light, which is made according to JISR3025, 3211 and 3212. Laminated glass that withstands impact tests and has a haze value of 1.0 or less. 2. The laminated glass according to claim 1, wherein a compound containing an acryloxy group or a methacryloxy group is added in an amount of 50% by weight or less of the ethylene-vinyl acetate copolymer as a curing aid. 3. The laminated glass according to claim 1, wherein a silane coupling agent of 5% by weight or less of the ethylene-vinyl acetate copolymer is added as an adhesive force improver.