JP2002080808A - Adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly transparent adhesive for bonding transparent glass plates and transparent acrylic resin plates which allows little warp or crack caused by temperature differences. SOLUTION: The adhesive comprises an acrylic syrup which yields a resin showing a storage elastic modulus, obtained from the dynamic viscoelasticity measured after curing, of from 1.0×109 to 4.0×109 Pa at 0 deg.C and from 1×105 to 1×108 Pa at 100 deg.C, and a haze of 3 in the form of a sheet with a thickness of 3 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive which is suitable for bonding a glass plate having a small coefficient of linear expansion to an acrylic resin plate having a large coefficient of linear expansion, has excellent transparency, and is laminated using the adhesive. The present invention relates to a laminate of a transparent glass plate and a transparent acrylic resin plate, which does not cause warpage, cracks, delamination, and the like.

[0002]

2. Description of the Related Art Acrylic resin plates, which are more transparent than other types of resins and lighter than glass, are often used for large aquariums under strong water pressure, such as those for aquariums, even when the thickness is large. When an acrylic resin plate is used for a water tank, algae may easily adhere to the inner surface, and therefore, a glass plate is laminated on the inner surface of the acrylic resin water tank.
When the lamination is performed using an ordinary adhesive for laminated glass, since the linear expansion coefficient of the acrylic resin is about 10 times that of the glass, the acrylic resin plate expands due to a temperature change or a temperature difference between both surfaces. In addition, there are problems such as shrinkage, warpage, and breakage of the glass plate, and further, when the thickness of the adhesive layer is increased, transparency is deteriorated. Further, as a method of manufacturing a laminated glass, there is a method of laminating glass plates via a spacer, sealing the ends with a rubber sheet such as butyl rubber, and then curing with light or the like (see Japanese Patent Publication No. 4-49501). This method has a problem that it is difficult to collectively irradiate the entire surface with light in large-area bonding of a large water tank or the like in terms of workability at an installation site.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, to provide a transparent glass which is excellent in transparency, hardly causes warping or cracking due to temperature change, and does not require special equipment for curing. An object of the present invention is to provide an adhesive between a plate and a transparent acrylic resin plate.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems. As a result, the use of a specific acrylic syrup has excellent transparency, and cracks due to a temperature difference are caused in the laminate. The present inventors have found that an adhesive which is hardly generated can be obtained, and have accomplished the present invention.

That is, according to the present invention, the storage elastic modulus determined by dynamic viscoelasticity measurement after curing is 1.0 × 10 3 at 0 ° C.
^{9 to} 4.0 × 10 ⁹ Pa, 1 × 10 ^{5 at} 100 ° C.
An acrylic syrup that gives a resin having a haze of 3 or less in a sheet having a thickness of 1 × 10 ⁸ Pa and a thickness of 3 mm, and an adhesive used for bonding a transparent glass plate and a transparent acrylic resin plate; This is a laminated plate obtained by laminating and integrating a transparent glass plate and a transparent acrylic resin plate using an adhesive.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The adhesive between the transparent glass plate and the transparent acrylic resin plate of the present invention has a storage elastic modulus of 1.0 × at 0 ° C. determined by dynamic viscoelasticity measurement alone after curing.
10 ^{9 to} 4.0 × 10 ⁹ Pa, 1 × 1 at 100 ° C.
0 a ^{5 ~1} × ¹⁰ 8 Pa, and the haze of the sheet having a thickness of 3mm is made of an acrylic syrup giving resin such that 3 or less.

The acrylic syrup referred to in the present invention is:
It is a composition obtained by dissolving a (meth) acrylic resin component in a (meth) acrylic monomer or a partial polymer of a (meth) acrylic monomer, and is a syrup-like high-viscosity liquid. Acrylic syrup is obtained by adding a radical polymerization initiator to a monomer composition mainly composed of methyl methacrylate and other (meth) acrylic monomers to be used as required, and heating in a prepolymerization tank to partially polymerize. Or a separately polymerized (meth) acrylic resin having a degree of polymerization in the range of 300 to 600, preferably in the range of 400 to 600, in the range of 10 to 20% by mass based on the (meth) acrylic monomer. , Preferably in the range of 13 to 16% by mass. The viscosity of the syrup is preferably in the range of 0.01 to 2 Pa · s from the viewpoint of ease of mixing and casting. The viscosity may be adjusted by additionally mixing a (meth) acrylic monomer after producing the syrup.

[0008] As the monomer used in the production of the acrylic syrup or the (meth) acrylic resin constituting the acrylic syrup, 80% by mass or more of the (meth) monomer is used.
It is preferably an acrylate monomer. Specific examples of (meth) acrylic monomers include methyl acrylate, methyl methacrylate, ethyl acrylate,
Butyl acrylate, butyl methacrylate, isoamyl acrylate, 2-ethylhexyl methacrylate,
Alkyl (meth) acrylates having an alkyl group having 1 to 18 carbon atoms such as lauryl acrylate, lauryl methacrylate, tridecyl methacrylate, stearyl acrylate; alkoxy having an alkoxy group having 1 to 4 carbon atoms such as butoxyethyl acrylate and methoxypropyl acrylate Alkyl (meth) acrylates; alkoxypolyalkylene glycol (meth) acrylates such as methoxydiethylene glycol acrylate and ethoxydiethylene glycol acrylate; aromatic (meth) acrylates such as phenoxyethyl acrylate and phenoxypolyethylene glycol acrylate; 2-hydroxyethyl acrylate, 2-hydroxy Propyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, etc. Hydroxyl group-containing (meth) acrylate;
And the like, and one or more of these can be used.

The monomer used in the production of the acrylic syrup or the (meth) acrylic resin constituting the acrylic syrup is, in addition to the above-mentioned (meth) acrylic acid ester monomer, 20% by mass. % Or less, other monomers, for example, aromatic monomers such as styrene and α-methylstyrene; nitrile monomers such as (meth) acrylonitrile; amide monomers such as (meth) acrylamide. Carboxylic acid monomers such as (meth) acrylic acid; maleic anhydride; maleimide; and the like.

Among the above-mentioned monomers, methyl acrylate, methyl methacrylate, ethoxydiethylene glycol acrylate, and the like are used in order to enhance the transparency and adhesive strength after curing of the obtained adhesive and keep the storage elastic modulus within an appropriate range.
It is preferable to use 2-hydroxy-3-phenoxypropyl acrylate in combination at an appropriate ratio.

In the adhesive of the present invention, it is necessary to select a composition which gives a resin having a haze of 3 or less when cured in a sheet having a thickness of 3 mm as an acrylic syrup constituting the adhesive. is there. When the haze of the resin is greater than 3, the transparency of a laminate obtained by laminating a transparent glass plate and a transparent acrylic resin plate becomes poor. 3mm thick
Is preferably 2 or less, more preferably 1 or less.

The adhesive of the present invention has a storage elastic modulus determined by a dynamic viscoelasticity measurement of a cured resin of 1. at 0 ° C.
It is necessary to select a composition such that the composition is in the range of 0 × 10 ^{9 to} 4.0 × 10 ⁹ Pa and 1 × 10 ⁵ to 1 × 10 ⁸ Pa at 100 ° C. When the storage elastic modulus of the cured resin is less than 1.0 × 10 ⁹ Pa at 0 ° C. or less than 1 × 10 ⁵ Pa at 100 ° C., the resin between the transparent glass plate and the transparent acrylic resin plate The adhesive layer is deformed over a long period of time, causing a gap between the transparent glass plate and the transparent acrylic resin plate. Also, the storage modulus is
At 0 ° C. above 4.0 × 10 ⁹ Pa or 10
If the temperature exceeds 1 × 10 ⁸ Pa at 0 ° C., the temperature rise causes the transparent acrylic resin plate to expand significantly as compared with the transparent glass plate, causing warpage, delamination or cracking. The storage elastic modulus is 1.0 × 10 ^{9 to} 3.0 × 1 at 0 ° C.
Within the range of ^{9 9} Pa and 1 × 10 ^{5 at} 100 ° C.
It is preferably in the range of 1 to 10 ⁷ Pa.

In order to make the storage elastic modulus at 0 ° C. and 100 ° C. fall within the range specified in the present invention, monomers used for producing an acrylic syrup are, for example, methyl methacrylate and alkoxypolyalkylene glycol such as ethoxydiethylene glycol acrylate. In the case of a monomer mixture containing (meth) acrylate, the storage modulus at 0 ° C. and 100 ° C. can be increased by increasing the proportion of methyl methacrylate, and the proportion of alkoxypolyalkylene glycol (meth) acrylate By increasing the storage modulus, the storage elastic modulus at 0 ° C. and 100 ° C. can be reduced. The mass ratio of methyl methacrylate to alkoxypolyalkylene glycol (meth) acrylate is 80:20 to 40: 6 from the viewpoint that the storage elastic modulus falls within the above range and a resin having a small haze is provided.
0, preferably 70:30 to 50: 5.
More preferably, it is within the range of 0.

It is preferable that the acrylic syrup contains a silane coupling agent in addition to the above-mentioned monomers in order to improve the adhesion to the glass plate. Examples of the silane coupling agent include γ- (meth) acryloyloxypropyltrimethoxysilane, γ- (meth) acryloyloxypropyltriethoxysilane, and γ- (meth) acryloyloxypropyl-tris (β-methoxyethoxy) silane (Meth) acryloyloxyalkylsilane; γ-aminopropyltriethoxysilane; and the like, and one or more kinds thereof can be used. Among these, those having an unsaturated double bond such as a (meth) acryloyloxy group are preferable, and γ- (meth) acryloyloxypropyltrimethoxysilane is more preferable. The content of the silane coupling agent is preferably from 0.5 to 5% by mass, more preferably from 0.7 to 2% by mass, based on the adhesive of the present invention. The acrylic syrup may further contain various additives, for example, fillers such as finely divided silica; polymerization inhibitors for extending the pot life; and various stabilizers for maintaining transparency over a long period of time. Good.

As the transparent acrylic resin plate laminated on the transparent glass plate with the adhesive of the present invention, a normal acrylic resin plate having a methyl methacrylate unit of 80% by mass or more can be used, and its total light transmittance Is preferably 80% or more. The thickness of the transparent acrylic resin plate is preferably 25 mm or more in order to more suitably exhibit the feature of having the adhesive of the present invention, that is, eliminating the distortion due to the difference in linear expansion coefficient between glass and acrylic resin and preventing warpage. Preferably, it is 30 mm or more. 25 thickness
As the acrylic resin plate having a thickness of not less than mm, any plate such as a cast plate or an extruded plate can be used, but a cast plate is preferable from the viewpoint of easy production of a thick plate.

The transparent glass plate laminated with the transparent acrylic resin plate by the adhesive of the present invention has a total light transmittance of 80%.
% Is preferable. The thickness of the transparent glass plate is preferably 1 mm or more in order to resist the tensile stress received via the adhesive layer due to the thermal expansion of the acrylic resin plate. Further, the transparent glass plate may have a special function such as lead glass for shielding X-rays or radiation, or reinforced glass having high surface hardness.

In the method of laminating and integrating the transparent glass plate and the transparent acrylic resin plate using the adhesive of the present invention, the transparent glass plate and the transparent acrylic resin plate are formed according to the desired thickness of the adhesive layer. This is performed by installing the spacer through a space, pouring the acrylic syrup constituting the adhesive of the present invention into the space, and curing the syrup. Examples of the method of curing the adhesive include a method of heating in the presence of a radical polymerization initiator, a method of curing at room temperature with a so-called redox initiator composed of a radical polymerization initiator and an accelerator, and the like. It is not limited to.

If the thickness of the adhesive layer is too small, the stress due to expansion or contraction of the acrylic resin plate is directly applied to the glass plate and the glass plate is cracked. Is more preferably within the range.

The layer structure of a laminate of a transparent glass plate and a transparent acrylic resin plate laminated and integrated with the adhesive of the present invention is as follows:
Three-layer structure consisting of transparent glass plate / adhesive layer / transparent acrylic resin plate, five-layer structure consisting of transparent glass plate / adhesive layer / transparent acrylic resin plate / adhesive layer / transparent glass plate, transparent acrylic resin plate / adhesive layer / transparent Any of a five-layer structure composed of a glass plate / adhesive layer / a transparent acrylic resin plate, or a layer structure of seven or more layers may be used. Further, as long as the effect of using the adhesive of the present invention is not impaired, even if a part or the whole part of the transparent acrylic resin plate or the transparent glass plate before bonding has a curved surface depending on the purpose of use and design of the laminated plate. Good.

The adhesive of the present invention can be used for producing a laminate having a large area and hence a large displacement due to expansion or contraction, such as a large aquarium tank, and a transparent acrylic plate having a large plate thickness, and therefore having a large expansion or contraction. It can be suitably used for manufacturing a laminated plate having a large stress. further,
The adhesive of the present invention can be used even when a thick transparent acrylic resin plate is laminated on a lead glass plate used for X-ray shielding windows in nuclear facilities or medical facilities for the purpose of neutron shielding and surface protection. It can be suitably used.

[0021]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. In addition, each characteristic in an Example and a comparative example was measured or evaluated as follows. (1) Preparation of test piece A resin sheet having a thickness of 3 mm was prepared in the same manner as in Example or Comparative Example except that the acrylic syrup was cured in a casting cell (spacer thickness: 3 mm) in which a release film was adhered to the inner surface. Obtained. (2) Dynamic viscoelasticity measurement Dynamic viscoelasticity measurement device "Rheospectral DVE-V4"
The storage elastic modulus (E ') of the resin sheet prepared in (1) under the following measurement conditions was determined using (Rheology). Waveform: Sine wave Vibration method: Continuous Load: Automatic static load 200% 15g Jig: Tension Specimen dimensions: thickness 3mm x width 3mm x length 20mm Measurement temperature range: -50 ° C to 200 ° C Temperature change rate: 3 ° C / min (3) Haze The haze of the resin sheet prepared in (1) was measured according to ASTM D1003.

Example 1 13.2. A methacrylic resin 13.2 having a polymerization degree of about 500 obtained by copolymerizing 13% by mass of methyl acrylate.
3 parts by mass of methyl methacrylate, 35 parts by mass of ethoxydiethylene glycol acrylate,
Hydroxy-3-phenoxypropyl acrylate 20
1 part by mass of γ-acryloyloxypropyltrimethoxysilane was dissolved in syrup (viscosity 0.027 Pa · s) dissolved in a monomer mixture consisting of parts by mass,
0.08 parts by mass of 2-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2-azobis (2,4
-Dimethylvaleronitrile) was added, stirred and defoamed to obtain an adhesive composed of an acrylic syrup.

A 3 mm thick transparent glass plate and a 40 mm thick transparent acrylic resin casting plate (Kuraray Paragrass) are combined via a 3 mm thick spacer, and the above adhesive is applied to the transparent glass plate and the transparent acrylic plate. Inject between the resin plate,
Curing was carried out in an air bath at 40 ° C. for 4 hours and then at 80 ° C. for 2 hours. The obtained laminate has no defects such as bubbles and cracks, and the storage elastic modulus of the resin obtained by curing the adhesive is 0 ° C.
1.25 × 10 ⁹ Pa at 100 ° C.
39 × 10 ⁵ Pa, the haze was 0.3, and the transparency was good. This laminate is placed in a thermostat at 50 ° C. for 8 hours.
As a result of performing a heat cycle at −30 ° C. for 16 hours eight times, defects such as cracks and delamination were not observed.

<Example 2> Two 30 mm transparent acrylic resin casting plates (Kuraray-made paragrass) were combined on both sides of a transparent lead glass plate having a thickness of 18 mm with a spacer having a thickness of 3 mm interposed therebetween. The same adhesive was injected between the glass plate and the transparent acrylic resin plate, and was cured by holding it at 40 ° C. for 4 hours and then at 80 ° C. for 2 hours in an air bath. The resulting flat laminate had no defects such as bubbles and cracks, and had good transparency.

Example 3 13.2 parts by weight of the same methacrylic resin as used in Example 1 was mixed with 45.8 parts by weight of methyl methacrylate, 20 parts by weight of ethoxydiethylene glycol acrylate, and 2-hydroxy-3-phenoxypropyl. Syrup (viscosity 0.025 Pa · s) dissolved in a monomer mixture consisting of 20 parts by mass of acrylate
Was dissolved 1 part by mass of γ-acryloyloxypropyltrimethoxysilane, and 0.08 parts by mass of 2,2-azobis (4-methoxy-2,4-dimethylvaleronitrile)
2,2-azobis (2,4-dimethylvaleronitrile)
0.02 parts by mass was added, stirred, and defoamed to obtain an adhesive composed of an acrylic syrup.

Using the same transparent glass plate and transparent acrylic resin plate as those used in Example 1, a laminated plate was obtained in the same manner as in Example 1. The obtained laminate had no defects such as bubbles and cracks, and the storage elastic modulus of the resin obtained by curing the adhesive was 1.18 × 10 ⁹ Pa at 0 ° C. and 2.5 at 100 ° C.
3 × 10 ⁵ Pa, haze was 0.3, and transparency was good. This laminate was placed in a thermostat at 50 ° C. for 8 hours.
As a result of performing a heat cycle of 16 hours at 30 ° C. eight times,
No defects such as cracks and delamination were observed.

<Comparative Example 1> Same as that used in Example 1.
30 parts by weight of methacrylic resin of methyl methacrylate 70
Syrup (viscosity 0.06Pa.
s): γ-acryloyloxypropyltrimethoxy
Dissolve 1 part by mass of silane and add 2,2-azobis (4-meth
(Xy-2,4-dimethylvaleronitrile) 0.08 mass
Part, 2,2-azobis (2,4-dimethylvaleronitrile
A) Add 0.02 parts by mass, stir, defoam and remove acrylic
An adhesive consisting of a system syrup was obtained. Use this adhesive
A laminated board was obtained in the same manner as in Example 1 except for the above. Got
The laminate had a crack in the adhesive layer. Adhesive layer
Has a storage elastic modulus of 5.21 × 10 at 0 ° C. ⁹
Pa, 2.08 × 10 at 100 ° C.⁹Pa and haze are 0.
1 and the transparency was good.

Comparative Example 2 16.1 parts by mass of the same methacrylic resin as used in Example 1 was mixed with 46.8 parts by mass of methyl methacrylate, 28.2 parts by mass of ethoxydiethylene glycol acrylate, and 2-hydroxy-3. Syrup (viscosity 0.011 Pa) dissolved in a monomer mixture consisting of 8.7 parts by mass of phenoxypropyl acrylate
In s), 0.2 parts by mass of γ-acryloyloxypropyltrimethoxysilane was dissolved, and 2,2-azobis (4
-Methoxy-2,4-dimethylvaleronitrile) 0.0
8 parts by mass and 0.02 parts by mass of 2,2-azobis (2,4-dimethylvaleronitrile) were added, stirred, and defoamed to obtain an adhesive composed of an acrylic syrup. A laminate was obtained in the same manner as in Example 1 except that this adhesive was used. When the same heat cycle as in Example 1 was performed on the obtained laminate, the adhesive layer was cracked in one cycle. The storage elastic modulus of the resin constituting the adhesive layer is 3.85 × 1 at 0 ° C.
0 ⁹ Pa, 100 ° C. at 7.23 × ¹⁰ 9 Pa, a haze of 0.2, the transparency was good.

[0029]

[Table 1]

[0030]

According to the present invention, it is possible to obtain an adhesive which is suitable for bonding a transparent glass plate having a small linear expansion coefficient to a transparent acrylic resin plate having a large linear expansion coefficient and which has excellent transparency after curing. When a transparent glass plate and a transparent acrylic resin plate are laminated using the adhesive of the present invention, a laminated plate free from warpage, cracks, delamination and the like can be obtained.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masao Ishii 1-12-13 Umeda, Kita-ku, Osaka-shi, Osaka F-term in Kuraray Co., Ltd. (Reference) 4F100 AG00A AK24C AK25B BA03 BA07 BA10A BA10C CB00B EC18 EJ08 GB07 GB90 JB13B JK07B JL00 JL11 JN01A JN01B JN01C YY00B 4J040 DF041 DF051 GA05 GA07 GA08 GA13 GA22 GA31 HD30 JA02 JB01 KA16 LA06 LA08 LA10 MA05 MA10 PA30

Claims (4)

[Claims] A storage elastic modulus determined by dynamic viscoelasticity measurement after curing is 1.0 × 10 ^{9 to} 4.0 × 10 at 0 ° C.
⁹ Pa, 1 × 10 ⁵ to 1 × 10 ⁸ Pa at 100 ° C.
And an acrylic syrup that gives a resin having a haze of 3 or less in a sheet having a thickness of 3 mm and is used for bonding a transparent glass plate and a transparent acrylic resin plate. 2. A silane coupling agent in an amount of 0.5 to 5% by mass.
The adhesive according to claim 1 which contains. 3. A laminated plate obtained by laminating and integrating a transparent glass plate and a transparent acrylic resin plate using the adhesive according to claim 1 or 2. 4. The laminate according to claim 3, wherein the thickness of the transparent acrylic resin plate is 25 mm or more.