JP5228423B2 - Curable resin composition, transparent laminate using the same, and method for producing the same - Google Patents

Description

  The present invention relates to a curable resin composition suitable for a method for producing a transparent laminate by curing a curable resin composition sandwiched between a pair of transparent substrates, and a transparent laminate using the curable resin composition. And a transparent laminate obtained by the production method.

Laminated glass with a pair of transparent glass substrates integrated through an adhesive layer is used as a windshield for automobiles because broken glass fragments adhere to the film and do not scatter, and it is difficult to penetrate and has excellent strength. Therefore, it is used as a window glass (safety glass, security glass) for buildings.
An adhesive layer in a laminated body such as laminated glass is required to have excellent transparency and good adhesion to a transparent substrate and tear resistance.

The following manufacturing methods are disclosed in Patent Documents 1 and 2 as a method for manufacturing a laminated glass. First, a flat container in which a pair of glass transparent substrates are bonded together with an adhesive spacer interposed therebetween is produced. At this time, a part of the spacer is opened. Next, after injecting an uncured curable resin composition from the opening of the spacer, the opening of the spacer is closed, and the curable transparent resin composition is cured to produce a laminated glass.
JP 2005-41747 A JP-A-60-51766

  However, in the methods described in Patent Documents 1 and 2, bubbles are generated when an uncured curable resin composition is injected into a flat plate container formed by a pair of transparent substrates, and it takes time to remove the bubbles. Therefore, there is dissatisfaction in terms of productivity.

  In addition, generally known acrylic or methacrylic curable resin compositions have no problem when cured in a relatively thin shape such as a coating film, an adhesive layer, or an adhesive layer. Since the layer has a relatively large thickness of about several hundred microns to several millimeters, the tear resistance and the adhesion to the transparent substrate may be insufficient due to non-uniformity of the curing reaction. This is thought to be because the viscosity of the composition rapidly increases due to the curing reaction during the curing process, and in particular, the photocuring with a high curing rate tends to increase the viscosity rapidly, and the curing reaction tends to become more uneven.

The present invention has been made in view of the above circumstances, and is a transparent laminate in which a pair of transparent substrates are integrated via an adhesive layer, and the tear resistance of the adhesive layer and the adhesion to the transparent substrate are good. The object of the present invention is to provide a curable resin composition capable of producing a transparent laminate having excellent transparency.
Another object of the present invention is to provide a production method capable of producing such a transparent laminate with good productivity while suppressing the generation of bubbles in an adhesive layer.

The curable resin composition of the present invention is a curable resin composition used in a method for producing a transparent laminate by curing a curable resin composition sandwiched between a pair of transparent substrates, and is a polyvinyl butyral resin And (a) and a hydroxyalkyl acrylate (b) having a hydroxyalkyl group having 4 carbon atoms having 1 or 2 hydroxyl groups.

The polyvinyl butyral resin (a) preferably has a viscosity of 0.03 Pa · s or more when a 10% by mass ethyl alcohol solution is used.
The hydroxyalkyl acrylate (b) is preferably a hydroxyalkyl acrylate having a hydroxyalkyl group having 4 carbon atoms having one hydroxyl group.
The content of the polyvinyl butyral resin (a) in the curable resin composition is preferably 3% by mass or more and 30% by mass or less.
The curable resin composition is preferably a photocurable resin composition containing a photopolymerization initiator.

The present invention provides a polyvinyl butyral resin (a) and a hydroxyalkyl acrylate having a C 2-8 hydroxyalkyl group having 1 or 2 hydroxyl groups between a pair of transparent substrates in a first atmosphere. The 1st process of forming the sealed space which stored the curable resin composition containing (b) inside, and the outside of the sealed space were made into the 2nd atmosphere whose pressure is higher than the 1st atmosphere. In the state, the manufacturing method of the transparent laminated body characterized by having the 2nd process of hardening the said curable resin composition is provided.
In the first step, a seal portion is provided along the periphery on the surface of one of the transparent substrates, and the curable resin composition is supplied into a region surrounded by the seal portion, in the first atmosphere. The other transparent substrate is pressed against the surface of the one transparent substrate to spread the curable resin composition, and the curable resin composition is sandwiched between the two transparent substrates. It is preferable to form a space.
It is preferable that the pressure of the first atmosphere is 1 kPa or less, the pressure of the second atmosphere is 10 kPa or more, and the difference between the two pressures is 100 kPa or more.
It is preferable that at least one of the pair of transparent substrates is a glass plate.
The pair of transparent substrates may be a pair of curved substrates having substantially the same curvature.

The present invention further includes a transparent laminate having a pair of transparent substrates and a cured resin layer sandwiched between the pair of transparent substrates, wherein the cured resin is a cured product of the curable resin composition. A transparent laminate is provided.
The transparent laminate is preferably a transparent laminate having a size having at least one side of 600 mm or more.

According to the curable resin composition of the present invention, a transparent laminated body in which a pair of transparent substrates are integrated via an adhesive layer, the tear resistance of the adhesive layer and the adhesion to the transparent substrate are good. And the transparent laminated body excellent also in transparency is obtained.
According to the method for producing a transparent laminate of the present invention, a pair of transparent substrates are integrated through an adhesive layer, and the tear resistance of the adhesive layer and the adhesion to the transparent substrate are good. A transparent laminated body fat composition that is excellent in transparency and can be produced with high productivity without requiring an operation of removing bubbles in the adhesive layer.
The transparent laminate of the present invention has good tear resistance of the adhesive layer and adhesion to the transparent substrate, and is excellent in transparency.

[(A) component]
The polyvinyl butyral resin (a) according to the present invention is a ternary copolymer composed of a vinyl acetal unit, a vinyl alcohol unit, and a vinyl acetate unit. The content of each unit in the resin is preferably 65 to 94% by mass of vinyl acetal units, 5 to 30% by mass of vinyl alcohol units, and 0.2 to 15% by mass of vinyl acetate units. The content of the vinyl acetal unit is usually 70% by mass or more. In terms of improving adhesiveness with the transparent substrate, it is preferable to have 10% by mass or more of vinyl alcohol units. In particular, it is preferable that the vinyl acetal unit is 75 to 85% by mass, the vinyl alcohol unit is 10 to 24% by mass, and the vinyl acetate unit is 0.5 to 10% by mass. The average degree of polymerization is preferably 500 to 2500.
The polyvinyl butyral resin (a) preferably has a viscosity (hereinafter sometimes referred to as solution viscosity) of 0.03 Pa · s or more when a 10% by mass ethyl alcohol solution is used. Specifically, the viscosity of the solution is the viscosity of a resin solution obtained by dissolving the polyvinyl butyral resin (a) to be measured in ethyl alcohol so that the resin concentration is 10% by mass. Thus, it is a value obtained by measurement at a measurement temperature of 25 ° C.
When the polyvinyl butyral resin (a) having a solution viscosity of 0.03 Pa · s or higher is used, it is preferable because the tear resistance of the adhesive layer is high, and the fracture of the adhesive layer can be suppressed when the glass is crushed. The solution viscosity is preferably 0.04 Pa · s or more. The upper limit of the solution viscosity is not particularly limited. Generally, it is 10 Pa · s or less.
As the polyvinyl butyral resin (a), commercially available products (for example, manufactured by Denki Kagaku Kogyo Co., Ltd., product name “Denka Butyral” series, etc.) can be appropriately used.

  Further, as the polyvinyl butyral resin (a), a plasticized polyvinyl butyral resin used for an interlayer film of laminated glass can also be used. The plasticized polyvinyl butyral resin is a resin obtained by plasticizing the polyvinyl butyral resin with a plasticizer. As the plasticizer, an aliphatic ester is suitable, and examples thereof include a diester of a diol such as triethylene glycol and a fatty acid, and a diester of an aliphatic dibasic acid and an aliphatic alcohol. The addition amount of the plasticizer is suitably 60 parts by mass or less, particularly 50 parts by mass or less with respect to 100 parts by mass of the polyvinyl butyral resin. In addition, the viscosity and content of the polyvinyl butyral resin (a) in this invention say the viscosity and content only about the polyvinyl butyral resin which does not contain a plasticizer.

[Component (b)]
The component (b) is a hydroxyalkyl acrylate having a C2-C8 hydroxyalkyl group having 1 or 2 hydroxyl groups. Specifically, an ester of acrylic acid (CH ₂ ═CH—COOR), wherein R is an alkyl group having 2 to 8 carbon atoms, and one of hydrogen atoms bonded to the alkyl group or It is a compound in which two are substituted with a hydroxyl group.
When the component (b) has a hydroxyl group, good adhesion to the transparent substrate is easily obtained. Those having 1 or 2 hydroxyl groups are easily available. If the number of hydroxyl groups is too large, the cured product may become too hard due to hydrogen bonding and become brittle.
R has 2 to 8 carbon atoms. When the number of carbon atoms is 1, the hydroxyl group density in the component (b) tends to be high, and when the curable resin composition combined with the component (a) is cured, some phase separation occurs in the course of the curing reaction. This may increase the haze of the cured product. Further, when the carbon number is 9 or more, the density of the hydroxyl group is lowered, so that the solubility of the component (a) may be lowered, or sufficient adhesion to the transparent substrate may not be obtained after curing.
In particular, when the number of hydroxyl groups in the hydroxyalkyl group of component (b) is 1 and the number of carbon atoms is 3 to 6, the cured product has high transparency and maintains a suitable flexibility. It is more preferable at the point which can obtain favorable adhesiveness.
Furthermore, when hydroxyalkyl methacrylate is used instead of hydroxyalkyl acrylate as component (b), the cured product may become cloudy due to partial phase separation during the curing reaction, and haze may be significantly increased. . Also, sufficient adhesion and tear strength cannot be obtained.

  Examples of compounds that can be used as the component (b) include 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 4-hydroxybutyl acrylate, and 6-hydroxyhexyl acrylate. Of these, 4-hydroxybutyl acrylate is preferred.

[Polymerization initiator]
The curable resin composition may contain a thermal polymerization initiator and may be a thermosetting resin composition,
Alternatively, a photopolymerization initiator may be contained to form a photocurable resin composition. The initiator is not particularly limited as long as it has an effect of promoting the curing reaction of the component (a) by heating or light irradiation, and a known initiator can be appropriately used.
As described above, when cured by light irradiation, the time required for the curing reaction is shorter, which is advantageous in terms of productivity. On the other hand, a molded product by photocuring with a large thickness such as an adhesive layer of laminated glass is used. In some cases, sufficient mechanical strength cannot be obtained due to a sudden increase in viscosity due to the curing reaction. On the other hand, since the photocurable resin composition according to the present invention can exhibit sufficient mechanical strength even by photocuring, it is particularly preferable for a method in which a photopolymerization initiator is contained and cured by light irradiation.
Photocuring is also preferred in that it saves energy and a transparent substrate that is easily thermally deformed can be used.

As the photopolymerization initiator, those that are excited and activated by irradiation with visible light or ultraviolet light (wavelength 300 to 400 nm) to accelerate the curing reaction are preferably used. Specific examples include benzoin ether, α-hydroxyalkylphenone, and acylphosphine oxide. These may be used alone or in combination of two or more.
Among these, preferable photopolymerization initiators include benzoin isopropyl ether, 1-hydroxy-cyclohexyl-phenyl-ketone, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl- Examples thereof include 1-propan-1-one and bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide. In particular, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, etc. The acyl phosphine oxide photopolymerization initiator is preferable because it can sufficiently cure the curable resin composition even when added in a small amount.

[Other reactive components]
The curable resin composition may contain other reactive components that cause a curing reaction at the same time in the step of curing the components (a) and (b) as long as the effects of the present invention are not impaired. .
The other reactive component is preferably one having a boiling point of 150 ° C. or higher at normal pressure in order to prevent the generation of bubbles in the vacuum lamination method described later. Examples of such other reactive components include amine compounds as curing accelerators, compounds having isocyanate groups that react with hydroxyl groups present in the molecules of (a) and (b), and adhesion to transparent substrates. And a silane coupling agent for improving the viscosity.
Moreover, when the polyfunctional curable compound which has 2-6 acryloyloxy groups, a methacryloyloxy group, or an isocyanate group in a molecule | numerator as other reactive components is contained in curable resin composition, it will be in hardened | cured material. A crosslinked structure can be imparted.
Note that methyl methacrylate, butyl acrylate, and the like that are commonly used as a curable compound have a boiling point of less than 150 ° C., and thus are preferably not contained.

[Other additives]
In addition, a polymerization inhibitor; a benzotriazole-based or hydroxyphenyltriazine-based UV absorber; a hindered amine-based light stabilizer, and the like may be appropriately added to the curable resin composition as necessary. Further, infrared rays can be absorbed by adding various pigments and dyes to change the transmitted light color of the transparent laminate, or by dispersing a minute amount of conductive fine particles such as ITO (indium tin oxide). Further, a plasticizer may be contained in order to adjust the elastic modulus and tensile strength of the cured product. In addition, fine particles and short fiber fillers with different refractive indexes from the cured curable resin composition are uniformly dispersed to change the state of transmitted light of the transparent laminate, or specified within the thickness range of the cured product The filler which implement | achieves this design can also be added.

[Content ratio]
The content of the polyvinyl butyral resin (a) in the curable resin composition is preferably 3 to 30% by mass, more preferably 5 to 20% by mass. When the content of the component (a) is 3% by mass or more, the tear resistance of the cured product is improved and the safety of the laminated glass is improved, and when it is 30% by mass or less, the flow of the curable resin composition This is preferable because it can be secured in a short time when sandwiched between transparent substrates.

  The content of the other reactive components is preferably 20% by mass or less, and more preferably 10% by mass or less. Zero is acceptable. When the polyfunctional curable compound is contained, if the content is too large, the cured product becomes brittle and the tear strength may be reduced.

When adding a photoinitiator, the addition amount is preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the total amount of components to be photocured among the component (b) and the other reactive components, 0.1-1 mass part is more preferable. The preferred amount of addition depends on the effect of promoting the curing of the photopolymerization initiator used. However, if the amount is not less than the lower limit of the above range, the effect of addition can be sufficiently obtained. This is preferable because it can reduce deformation.
When adding a thermal polymerization initiator, the addition amount is preferably 0.5 to 3 parts by mass with respect to 100 parts by mass of the total amount of components to be thermally cured among the component (b) and the other reactive components, 0.5-1 mass part is more preferable. When the amount is not less than the lower limit of the above range, the effect of addition can be sufficiently obtained, and when the amount is not more than the upper limit, the molecular weight of the cured product can be increased and tear resistance can be improved.

[viscosity]
The value of the viscosity in this specification is a value measured by the following method. About 10 g of the sample to be measured is put into a container for viscosity measurement (HT-2DB-100 manufactured by Brookfield), and the sample is set in a heat retention machine for viscosity measurement so that the temperature of the sample is 25 ° C. Next, a measuring spindle (Brookfield SC4-31) attached to a viscometer (Brookfield LVDV-II + pro) is immersed in the sample in the measuring container, and 0 is added depending on the viscosity of the sample. After holding the spindle set at a speed in the range of 3 to 100 rpm for 15 minutes, the viscosity of the sample is measured (V ₂₅ ).

In the curable resin composition, as the proportion of the component (b) having a low molecular weight increases, the viscosity of the composition decreases. Moreover, the viscosity of this composition increases, so that the solution viscosity of (a) component is high.
When the viscosity (V ₂₅ ) at 25 ° C. in the uncured state of the curable resin composition is 0.05 Pa · s or more, it is easy to suppress shrinkage of the cured product resulting from curing before and after curing. If the shrinkage before and after curing is large, the cured product remains strained and the mechanical strength tends to decrease. Further, when the curable resin composition is sandwiched between a pair of transparent substrates by using a vacuum lamination method, when V ₂₅ is 0.15 Pa · s or more, particularly 0.5 Pa · s or more, it is dropped onto the transparent substrate. When the curable resin composition is superposed on the other transparent substrate, it is effective and preferable for preventing overflowing from a seal formed in advance around the transparent substrate.
In the methods described in Patent Documents 1 and 2, that is, a method of injecting and curing a curable resin composition between substrates after sealing (hereinafter referred to as injection filling method), a curable resin composition having a high viscosity is used. It is difficult to use. Even if a curable resin composition having a high viscosity can be injected into a narrow substrate gap, it is very difficult to remove bubbles generated in the injected curable resin composition or between the curable resin composition and the substrate. In the case of using the injection filling method, V ₂₅ of the curable resin composition is required to be less than 0.15 Pa · s, and preferably 0.10 Pa · s or less, in order to easily perform defoaming. Accordingly, among the curable resin compositions of the present invention, those having a V ₂₅ of 0.05 Pa · s or more and less than 0.15 Pa · s are suitable for application to the injection filling method, and those having a V ₂₅ of 0.15 Pa · s or more are suitable. Suitable for application to vacuum lamination.

<Method for producing laminate>
1 to 4 illustrate an embodiment of a vacuum lamination method suitable for producing a transparent laminate (hereinafter sometimes simply referred to as a laminate) using the curable resin composition of the present invention. FIG. 1B is a cross-sectional view taken along the line bb in FIG. 1A, and FIG. 2B is a cross-sectional view taken along the line bb in FIG. 2A. The manufacturing method of the laminated body of this embodiment is demonstrated based on these figures.
First, a pair of rectangular transparent substrates 10a and 10b are prepared. As shown in FIG. 1, a double-sided adhesive type sealing material 12 is fixed along the four side edges of one transparent substrate 10a. In this embodiment, the double-sided tape 12 is stuck as the sealing material 12. The sealing material 12 preferably has the same degree of transparency (light transmittance) as the cured product of the curable resin composition 14.

Next, as shown in FIG. 2, a curable resin composition 14 is supplied into a rectangular region 13 surrounded by the sealing material 12 of the transparent substrate 10a. The supply amount of the curable resin composition 14 is such that the sealed space surrounded by the sealing material 12 and the pair of transparent substrates 10a and 10b, which is formed in a later step, is filled with the cured product of the curable resin composition 14. Set the amount to be At this time, the volume of the sealed space is calculated on the assumption that deformation such as deflection due to the weight of the transparent substrate does not occur.
The method of supplying the curable resin composition 14 may be coating or dropping. In the present embodiment, the transparent substrate 10a is laid flat on the lower surface plate 18, and the curable resin composition 14 is applied in a linear shape, a strip shape, or a dot shape using the dispenser 20 that moves in the horizontal direction. The dispenser 20 can be horizontally moved over the entire range of the region 13 by a known horizontal movement mechanism including a pair of feed screws 22 and 22 and a feed screw 24 orthogonal to the feed screws 22 and 22. Yes. In addition, it can replace with the dispenser 20 and a die-coat application means can also be applied.
Although not essential, in the present embodiment, the sealing curable resin 36 is applied to the upper surface of the sealing material 12. The sealing curable resin 36 may be the same as the curable resin composition 14 of the present invention, or a different curable resin may be used. As the curable resin, an ultraviolet curable curable resin is preferable. When the curable resin composition 14 of the present invention is a thermosetting curable resin composition, a thermosetting resin can also be used as the sealing curable resin.

Thus, the one transparent substrate 10a and the other transparent substrate 10b on which the curable resin composition 14 is applied are accommodated in the decompression chamber 26 as shown in FIG. In the decompression chamber 26, one transparent substrate 10a is held horizontally such that the surface on which the curable resin composition 14 is applied is the upper surface. The other transparent substrate 10b is sucked and held horizontally above one transparent substrate 10a by suction pads 32, 32. The suction pad may be an adhesive pad using an adhesive material. The upper surface plate 30 can be driven up and down by an air cylinder 34. The number of the suction pads 32 and the attachment position with respect to the upper surface plate 30 can be appropriately changed depending on the size of the transparent substrate 16 and the like.
Then, the air in the decompression chamber 26 is sucked by the vacuum pump 28 to make the inside of the decompression chamber 26 a decompressed atmosphere (first atmosphere). The pressure of the reduced-pressure atmosphere (first atmosphere) is preferably 1 kPa or less, more preferably 10 to 100 Pa, and further preferably 30 to 50 Pa. It is easy to prevent bubbles from remaining in the curable resin composition 14 when the pressure of the first atmosphere is 1 kPa or less. When the pressure is less than 10 Pa, the degree of vacuum is high, so that the time loss when building the vacuum environment is large. Further, if the degree of vacuum is too high, there is a possibility that the thermal polymerization initiator contained in the curable resin composition 14 or additives such as a photopolymerization initiator, a polymerization inhibitor, and a light stabilizer may partly volatilize. There is.

In this state, the air cylinder 34 is operated to lower the other transparent substrate 10b and superimpose it on the one transparent substrate 10a. That is, the other transparent substrate 10b is pressed against the upper surface of one transparent substrate 10a, and the curable resin composition on the transparent substrate 10a is spread and overlapped.
Furthermore, by holding at a reduced pressure atmosphere (first atmosphere) for a predetermined time, a sealed space in which the curable resin composition 14 is sandwiched in the gap between the two transparent substrates 10a and 10b is formed. In other words, the pair of transparent substrates 10a and 10b are in a state of being laminated via the sealing material 12 and the sealing curable resin 36 (uncured laminate), and the sealing material 12 and the pair of transparent substrates 10a and 10b An enclosed sealed space is formed. The curable resin composition 14 is accommodated in this sealed space, and portions other than the curable resin composition 14 in the sealed space are in the same reduced pressure state (vacuum state) as the first atmosphere.

Next, the inside of the decompression chamber 26 is changed to a second atmosphere whose pressure is higher than that of the first atmosphere. The pressure of the second atmosphere is preferably 10 kPa or more, and the difference between the pressure of the first atmosphere and the pressure of the second atmosphere is preferably 100 kPa or more. For example, the inside of the decompression chamber 26 is opened to the atmosphere. If the pressure of the second atmosphere is atmospheric pressure, it is convenient because no equipment for maintaining a specific pressure is required. As a result, the outside of the sealed space surrounded by the sealing material 12 and the pair of transparent substrates 10a and 10b becomes a second atmosphere whose pressure is higher than that of the first atmosphere. Thus, the pair of transparent substrates 10a and 10b are pressed in a direction in which they are in close contact with each other. Along with this, the curable resin composition 14 flows to a portion other than the curable resin composition 14 in the sealed space, and the entire sealed space is uniformly filled with the curable resin composition 14.
Thereafter, the sealing curable resin 36 and the curable resin composition 14 are cured, so that the pair of transparent substrates 10a and 10b are integrated through an adhesive layer made of a cured product of the curable resin composition 14. A transparent laminate is obtained.

For example, when the curable resin 36 for sealing and the curable resin composition 14 in the sealed space are ultraviolet curable resin compositions, these are cured using the ultraviolet irradiation device 40 shown in FIG. Can do.
The ultraviolet irradiation device 40 includes a mirror or the like as an ultraviolet light source using a high-pressure mercury lamp or a metal halide lamp. It is also possible to use a plurality of chemical lamps or black lights that are connected in series. In addition, what is necessary is just to heat and harden | cure, when the curable resin composition 14 is a thermosetting resin composition.

  In the above embodiment, the sealing curable resin 36 is not essential, but if the sealing curable resin 36 is applied on the double-sided tape 12, the adhesion is improved and the sealing degree of the sealed space is improved. When opening to atmospheric pressure, it is preferable for maintaining the degree of vacuum (vacuum) in the sealed space. Further, when the pair of transparent substrates are bonded to each other under reduced pressure, the distance between the transparent substrates can be increased by the coating thickness of the sealing curable resin 36, and the curable resin composition supplied in the seal 14 can be prevented from locally leaking from the seal when the pair of transparent substrates are joined. After being released to the atmosphere, the curable resin 36 for sealing spreads on the seal due to the differential pressure, and the coating thickness becomes sufficiently small. Therefore, the volume change of the predetermined sealed space hardly causes a problem. Further, instead of the double-sided tape, a mixture of spacer particles mixed with a highly viscous curable resin for sealing different from the curable resin composition 14 so as to maintain a predetermined seal thickness may be applied.

<Transparent substrate>
The transparent substrates 10a and 10b are not particularly limited, and may be an inorganic transparent substrate such as glass or a resin transparent substrate.
The transparent substrate is preferably made of glass or resin. In the case of a glass plate, a laminated glass is obtained. If polycarbonate is applied as the resin plate, it is possible to provide a transparent panel having high impact and light weight. Moreover, you may join a glass plate and a resin plate with a curable resin composition. The size of the transparent substrate is not particularly limited, but if it is a transparent substrate having at least one side of 300 mm or more, more preferably 600 mm or more, it can be widely used as a transparent member installed in an opening for buildings or vehicles. Can provide transparent panels. There is no particular upper limit to the size of the transparent substrate, but a size of 4 m ² or less is appropriate for normal use.

At least one of the pair of transparent substrates 10a and 10b has a functional group capable of being chemically bonded to the curable resin composition 14 when the curable resin composition 14 is cured on the surface in contact with the curable resin composition 14. It is preferable that a layer made of a surface treatment agent is provided. Thereby, the adhesiveness of the contact bonding layer which consists of hardened | cured material of the curable resin composition 14, and a transparent substrate improves, and the mechanical strength of a laminated body improves. Therefore, it is suitable for laminated glass that requires high strength. A known titanium compound or silane compound can be used as the surface treating agent.
Examples of the silane compound include silane coupling agents such as 3-methacryloxypropyltrimethoxysilane. In the case of using a silane compound, as an example of a specific method of use, first, a solution of silane compound: water: iPA (isopropyl alcohol) = 0.3: 0.5: 99.2 is stirred at room temperature for 10 hours, and silane By hydrolyzing the compound, a solution partially or completely silanolated is obtained. Next, after the transparent substrate is dipped in this solution for 1 minute and pulled up, it can be heat treated in an oven at 150 ° C. for 30 minutes to react with the glass surface.

  Further, the pair of transparent substrates 10a and 10b may be curved substrates having substantially the same curvature. For example, when a pair of transparent substrates 10a and 10b are integrated through an intermediate layer formed in a film shape, if the transparent substrate is a curved substrate with a large curvature, wrinkles occur in the film, making it difficult to manufacture a laminate. is there. On the other hand, in the vacuum lamination method of the present invention, the adhesive layer is formed so as to follow the shape of the transparent substrate. Therefore, the shape of the transparent substrate is not limited, and the transparent three-dimensionally curved curvature is relatively large. Even a substrate can be used.

<Transparent laminate>
According to the present invention, a transparent laminate in which a pair of transparent substrates are integrated via an adhesive layer made of a cured product of the curable resin composition of the present invention is obtained. The thickness of the adhesive layer is preferably 0.2 to 4.0 mm. When the thickness of the adhesive layer is 0.2 mm or more, good mechanical strength of the laminate is easily obtained. Further, according to the present invention, since the unevenness of the curing reaction can be suppressed, even if the thickness of the adhesive layer is as large as about 4.0 mm, the distortion of transmitted light due to the uneven refractive index of the cured product is reduced. A laminate that can be suppressed and has good adhesion to the transparent substrate is obtained.
Further, the cured product of the curable resin composition is excellent in transparency and has a haze value of 6% or less, preferably 3% or less, more preferably 2% or less, and even more preferably 1% or less. An excellent transparent laminate can be obtained.

Further, when the thickness of the adhesive layer is Ts, the thinner one of the pair of transparent substrates 10a and 10b is T1, and the thicker one is T2, the thickness Ts of the adhesive layer satisfies the following formula (1). It is preferable to do. T1 and T2 may have the same thickness.
T1 × 0.05 ≦ Ts ≦ T2 × 1.5 (1)
That is, when the thickness Ts of the adhesive layer is 5% or more with respect to the thinner thickness of the pair of transparent substrates, it is easy to ensure the strength as a laminate, and 150% with respect to the thicker thickness of the transparent substrate. If it exceeds, the thickness of the laminate becomes unnecessarily thick.

By using the curable resin composition of the present invention for the adhesive layer of the laminate, good optical characteristics with a small haze value and optical distortion can be obtained even when the adhesive layer is relatively thick. This is because, by using a specific polymer compound (component (a)) and a specific low molecular weight curable component (component (b)) in combination, the effect of introducing the component (a) having a higher molecular weight, It is considered that the tear resistance is improved by increasing the cohesive force inside the cured product due to intermolecular hydrogen bonding between the cured product of component b) and component (a). Further, by using the component (b) having a specific molecular structure, the component (a) can be dissolved uniformly, and at the same time, the adhesion to the transparent substrate can be improved.
In particular, when the curable reactive group of the component (b) is an acryloyloxy group, the curability is further enhanced, and it is possible to suppress the occurrence of phase separation after curing, so that a highly transparent laminated glass is easily obtained.
Therefore, by using the curable resin composition of the present invention as an adhesive layer of a transparent substrate, the adhesive layer exhibits high mechanical strength and good adhesion to the substrate, and also exhibits good transparency. Therefore, a transparent laminate having high impact resistance, good optical quality, and excellent safety performance can be obtained.
Moreover, the curable resin composition of this invention can be used suitably for a vacuum lamination method, and can manufacture a transparent laminated body. In the vacuum lamination method, since a pair of transparent substrates are brought into close contact with each other under an atmosphere under reduced pressure in a vacuum, bubbles are hardly generated in the adhesive layer. Therefore, a process is not required to remove such bubbles, and a transparent laminate can be produced with high productivity.
In the vacuum lamination method, a composition having a relatively high viscosity or a composition having a high molecular weight can be used as the curable resin composition, so that a cured product having a high strength is obtained when cured, and a transparent material having a high mechanical strength as a whole. A laminate can be obtained. Therefore, it is possible to sufficiently obtain the mechanical strength of the transparent laminate by reducing the thickness of the adhesive layer.

Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited to these examples.
[Examples 1 to 16]
In the formulation shown in Table 1, each component was mixed to prepare a curable resin composition. The unit of the blending amount in Table 1 is part by mass.
Moreover, the viscosity at 25 degreeC of some obtained curable resin compositions was measured, respectively. The results are shown in Table 1. "-" In the column of "Viscosity of uncured product" in Table 1 indicates that the viscosity is not measured. However, since the viscosity of the composition is substantially determined by the solution viscosity of the component (a) and the content ratio thereof, the viscosity of the composition in Examples 1 to 3, 5, 8, 9, and 12 to 16 is that of Example 4. It is approximately equal to or greater than the viscosity of the composition. This has been confirmed in the handling of the curable resin composition in the production of the laminated body of each example.

Each component described in Table 1 is as follows.
Polyvinyl butyral resin 1: product name “Denka Butyral # 3000-1”, manufactured by Denki Kagaku Kogyo Co., Ltd. The measured value of the viscosity of a 10% by mass resin solution at 25 ° C. is about 0.05 Pa · s. It is recognized as a terpolymer having an average degree of polymerization of about 600 having a vinyl acetal unit of 80% by mass, a vinyl alcohol unit of 19% by mass and a vinyl acetate unit of 1% by mass.
Polyvinyl butyral resin 2: Product name “Denka Butyral # 5000-A”, manufactured by Denki Kagaku Kogyo Co., Ltd. The measured value of the viscosity of a 10% by mass resin solution at 25 ° C. is about 1.7 Pa · s. It is recognized as a ternary copolymer having 83% by mass of vinyl acetal units, 16% by mass of vinyl alcohol units and 1% by mass of vinyl acetate units and an average degree of polymerization of about 2000.
Polyvinyl butyral resin 3: Product name “Denka Butyral # 6000-C”, manufactured by Denki Kagaku Kogyo Co., Ltd. The measured value of the viscosity of a 10% by mass resin solution at 25 ° C. is about 3.7 Pa · s. It is recognized as a terpolymer having 83% by mass of vinyl acetal units, 16% by mass of vinyl alcohol units, and 1% by mass of vinyl acetate units and an average degree of polymerization of about 2400.
-Urethane acrylate: Urethane oligomer having an acryloyl group (product name "EB230", manufactured by Daicel-Cytec). The number of functional groups is 2, and the measured value of viscosity at 25 ° C. is about 56 Pa · s. It is recognized as a reaction product of polypropylene glycol having a number average molecular weight of about 3000, isophorone diisocyanate and 2-hydroxyethyl acrylate.

_{· CH 2 = CHCO (OC 2} H 4) n -OH: n ≒ 2 ( product name: "AE-90", manufactured by Nippon Oil & Fats Co., Ltd.).
CH ₂ = CHCO (OC ₃ H ₆ ) _n —OH: n≈3 (product name “AP-150”, manufactured by NOF Corporation).
_{· CH 2 = C (CH 3} ) CO (OC 2 H 4) n -OH: n ≒ 2 ( product name "PE-90", manufactured by NOF Corporation).
_{· CH 2 = CHCOOCH 2 CH (} OH) CH 2 OC 15 H 31 :( product name "EBECRYL 112", manufactured by Daicel-Cytec Co., Ltd.).
Polymerization initiator 1: benzoin isopropyl ether.
Polymerization initiator 2: Bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (product name “IRGACURE 819”, manufactured by Ciba Specialty Chemicals).

[Manufacture of laminates]
Laminated glass (transparent laminate) was produced using each of the curable resin compositions obtained in Examples 1 to 16. Each curable resin composition was stored in a vacuum chamber in an open state while being put in a container, and the chamber was decompressed to about 200 Pa · s and held for 10 minutes for defoaming treatment before use.
First, two pieces of soda lime glass having a length of 610 mm, a width of 610 mm, and a thickness of 2 mm were prepared. After sticking a double-sided tape (sealing material 12) having a thickness of 1 mm and a width of 10 mm along the edges of one side of the transparent substrate 10a, the release film on the upper surface of the double-sided tape was removed.
The UV curable resin 36 for sealing prepared by uniformly mixing 100 parts by mass of urethane acrylate oligomer (product name “UF8001G”, manufactured by Kyoeisha Chemical Co., Ltd.) and 1 part by mass of benzoin isopropyl ether (polymerization initiator) in advance, It apply | coated with the dispenser with the application | coating thickness of about 0.3 mm on the upper surface of the double-sided tape.

Next, regarding the curable resin composition (Examples 1 to 6, 8, 9, 12 to 16), the curable resin is in a region surrounded by the double-sided tape on the surface of the transparent substrate 10a to which the double-sided tape is applied. The composition 14 was dropped at a plurality of locations using a dispenser so that the total weight was 380 g. Next, the transparent substrate 10a was placed horizontally in a vacuum chamber as shown in FIG.
Next, the other transparent substrate 10b is held on the upper surface plate 30 in the vacuum chamber using the suction pads 32, 32..., And is opposed in parallel to the transparent substrate 10a and is a distance from the transparent substrate 10a. Was held at 10 mm.

  Next, the vacuum chamber was sealed and evacuated until the inside of the chamber was about 30 Pa. At this time, the dropped composition did not continue to foam. Thereafter, the upper and lower surface plates were brought close to each other by a lifting device, and the transparent substrate 10a and the transparent substrate 10b were pressure-bonded with a pressure of 2 kPa and held for 1 minute. Thereafter, the inside of the vacuum chamber was returned to atmospheric pressure in about 30 seconds, and a precursor in which the transparent substrate 10a and the transparent substrate 10b were in close contact with each other through the uncured layer of the curable resin composition 14 was obtained.

  Next, the upper and lower surface plates were separated by the lifting device, and the precursor adhered to the suction pads 32, 32... Of the upper surface plate 30 was peeled from the upper surface plate 30. . Next, ultraviolet light is irradiated from the fiber light source using a high-pressure mercury lamp as a light source to the portion where the double-sided tape on the outer peripheral portion of the precursor is present through the other transparent substrate 10b, Cured. Thereafter, the precursor was kept horizontal and allowed to stand for about 1 hour.

On the other hand, in the case of a curable resin composition having a viscosity (V ₂₅ ) of an uncured product at 25 ° C. of less than 0.15 Pa · s, liquid leakage occurs from the sealing portion when the vacuum chamber is returned to atmospheric pressure. Application of the method was difficult (Note that the curable resin composition with V ₂₅ of 0.15 Pa · s or more cannot be defoamed from the injected curable resin composition, and the following injection filling method cannot be used. ) Therefore, with respect to the curable resin composition (Examples 7, 10, and 11) having a V ₂₅ of less than 0.15 Pa · s, they are pasted together through a double-sided tape seal in which a pair of transparent substrates are previously pasted around the seal. Was partially peeled to provide an opening, and a predetermined amount of the curable resin composition was injected between the transparent substrates using a syringe from the gap. Next, after standing for a long time in a vertical position and collecting the mixed bubbles on the upper side of the seal, the air bubbles collected at the upper part were pushed out, and the injection port was again brought into close contact with a double-sided tape seal to seal it. Thereafter, the precursor was kept horizontal and allowed to stand for about 24 hours.

Next, the curable resin composition 14 is cured by irradiating with ultraviolet rays having an intensity of 1 mW / cm ² for 10 minutes from both sides of the precursor with an ultraviolet irradiator uniformly provided with chemical lamps. A laminate (laminated glass) was obtained.

[Evaluation]
(Haze value)
A haze value was measured as an evaluation of transparency for a portion where the adhesive layer of the obtained transparent laminate was present. The results are shown in Table 1. The haze value was measured by measurement according to ASTM D 1003 using a haze guard II manufactured by Toyo Seiki Seisakusho. The results are shown in Table 1.

(Adhesion)
Only a part of one transparent substrate 10a of the transparent laminate was removed to expose the adhesive layer (cured product) and peeled off from the other transparent substrate 10b, and the adhesion was evaluated according to the following criteria. The results are shown in Table 1.
○: The adhesive layer was greatly deformed when the adhesive layer was peeled off.
Δ: The adhesive layer was slightly deformed when the adhesive layer was peeled off.
X: The adhesive layer hardly deformed when the adhesive layer was peeled off.

(Tear strength)
Only a part of one transparent substrate 10a of the transparent laminate is removed to expose the adhesive layer (cured product), and a part of the adhesive layer (cured product) from the other transparent substrate 10b (a size of about 1 cm × 2 cm). ) Was peeled to obtain a test piece. The obtained test piece was torn about 1 mm in the center of the long side, and the tear strength was evaluated according to the following criteria. The results are shown in Table 1.
○: The adhesive layer was greatly deformed and stretched when torn.
Δ: The adhesive layer was deformed when it was torn, but the elongation was small.
X: When tearing, the adhesive layer was easily torn with almost no deformation.

(Falling ball test)
The laminated body obtained in Example 4 was subjected to a falling ball test. In the test, the laminate was placed on a test frame of JIS R 3205 and an iron ball having a weight of 4.11 kg was dropped from a height of 1.5 m onto the center of the laminate. The test was performed in an atmosphere in which the room temperature was controlled at 23 ± 2 ° C.
As a result of the test, the iron balls did not penetrate the laminate. Subsequently, an iron ball was dropped on the same specimen twice from the same height, but did not penetrate.

As shown in the results of Table 1, in Examples 1 to 9 according to the present invention, the haze is low and the transparency is excellent, and the adhesion to the substrate and the tear resistance are also good.
In Example 10 in which a relatively high molecular weight urethane acrylate oligomer was used instead of the component (a), strong white turbidity occurred, and adhesion and tear resistance were also inferior. Further, Example 11 containing no component (a) and only component (b) had no white turbidity and had sufficient transparency, but had poor adhesion and tear resistance.
In Example 12, in which instead of the component (b), a methacrylate having a hydroxyl group-containing ester part having 4 carbon atoms was used, white turbidity occurred, and adhesion and tear resistance were also poor. Similarly, in Examples 13 to 15 using a (meth) acrylate having a hydroxyl group and a polyoxyalkylene chain instead of the component (b), the adhesion and tear resistance were all poor. In Example 16 in which an acrylate having a hydroxyl group and an ester part containing an ether bond and having 18 carbon atoms was used instead of the component (b), adhesion and tear resistance were poor.

It is explanatory drawing of the process of providing a sealing material in one Embodiment of the manufacturing method of this invention, (A) is a top view, (B) is sectional drawing which follows the bb line in (A). It is explanatory drawing of an application | coating process in one Embodiment of the manufacturing method of this invention, (A) is a top view, (B) is sectional drawing which follows the bb line in (A). It is explanatory drawing of the process of forming sealed space in one Embodiment of the manufacturing method of this invention. It is explanatory drawing of the hardening process by light irradiation in one Embodiment of the manufacturing method of this invention.

Explanation of symbols

10a ... one transparent substrate,
10b ... the other transparent substrate,
12 ... sealing material,
14 ... curable resin composition,
26 ... decompression chamber,
28 ... Vacuum pump,
36: curable resin for sealing,
40 ... UV irradiation device,
42 ... High pressure mercury lamp.

Claims (12)

A curable resin composition used in a method for producing a transparent laminate by curing a curable resin composition sandwiched between a pair of transparent substrates,
A curable resin composition comprising a polyvinyl butyral resin (a) and a hydroxyalkyl acrylate (b) having a hydroxyalkyl group of 4 carbon atoms having 1 or 2 hydroxyl groups.   The curable resin composition according to claim 1, wherein the polyvinyl butyral resin (a) has a viscosity of 0.03 Pa · s or more when a 10% by mass ethyl alcohol solution is used. The curable resin composition according to claim 1 or 2, wherein the hydroxyalkyl acrylate (b) is a hydroxyalkyl acrylate having a hydroxyalkyl group having 4 carbon atoms and having 1 hydroxyl group.   The curable resin composition according to any one of claims 1 to 3, wherein a content of the polyvinyl butyral resin (a) in the curable resin composition is 3% by mass or more and 30% by mass or less.   The curable resin composition according to any one of claims 1 to 4, wherein the curable resin composition is a photocurable resin composition containing a photopolymerization initiator.   A curable resin composition according to any one of claims 1 to 5, wherein the curable resin composition is a transparent laminate having a pair of transparent substrates and a cured resin layer sandwiched between the pair of transparent substrates. A transparent laminate that is a cured product of the above. The transparent laminate according to claim 6 , wherein the transparent laminate has a size having at least one side of 600 mm or more.
In a first atmosphere, between a pair of transparent substrates, a polyvinyl butyral resin (a) and a hydroxyalkyl acrylate (b) having a C2-C8 hydroxyalkyl group having 1 or 2 hydroxyl groups. A first step of forming a sealed space containing the curable resin composition contained therein ;
A transparent laminate having a second step of curing the curable resin composition in a state where the outside of the sealed space is a second atmosphere having a pressure higher than that of the first atmosphere. Production method. In the first step, a seal portion is provided along the periphery on the surface of one of the transparent substrates, and the curable resin composition is supplied into a region surrounded by the seal portion, in the first atmosphere. The other transparent substrate is pressed against the surface of the one transparent substrate to spread the curable resin composition, and the curable resin composition is sandwiched between the two transparent substrates. The manufacturing method of the transparent laminated body of Claim 8 which forms space. The method for producing a transparent laminate according to claim 8 or 9 , wherein the pressure of the first atmosphere is 1 kPa or less, the pressure of the second atmosphere is 10 kPa or more, and the difference between the two pressures is 100 kPa or more. . The method for producing a transparent laminate according to any one of claims 8 to 10 , wherein at least one of the pair of transparent substrates is a glass plate. The method for producing a transparent laminate according to any one of claims 8 to 11 , wherein the pair of transparent substrates is a pair of curved substrates having substantially the same curvature.

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