WO2022255382A1 - Composition for temporary fixing of thin layer glass, and method for processing thin layer glass - Google Patents

Abstract

The present invention provides a single component composition for temporary fixing of thin layer glass. The composition exhibits excellent photocuring properties and enables thin layer glasses to be strongly temporarily fixed to each other while enabling the thin layer glasses to be easily peeled from each other in a short time at the time of peeling. This composition for temporary fixing of thin layer glass contains a monofunctional acrylic monomer, a polyfunctional monomer, thermally expandable fine particles and a radical photopolymerization initiator having a molar absorption coefficient ε of 100 L/(mol·cm) or more at a wavelength of 400 nm, exhibits excellent photocuring properties, and enables thin layer glasses to be temporarily fixed to each other regardless of stress at the time of processing while enabling the thin layer glasses to be easily peeled from each other in a short time with no damage following processing of the thin layer glasses.

Description

Thin-layer glass temporary fixing composition and thin-layer glass processing method

The present invention relates to a thin-layer glass temporary fixing composition and a thin-layer glass processing method.

Thin-layer glass is used in portable electronic devices such as smartphones and tablet terminals, and glass substrates for solar cells. A single sheet of thin glass is extremely thin and weak in strength. is being improved, and the laminated thin glass is processed.

After the processing of the thin-layer glass is completed, the laminated thin-layer glass is peeled off one by one. requested.

Temporary fixing agents include (1) (1-1) imide (meth)acrylate and/or cyclic trimethylolpropane formal (meth)acrylate, (1-2) urethane (meth)acrylate, ( 1-3) polyfunctional (meth)acrylate other than (1-2), (1-4) polymerizable vinyl derivative containing alkyl (meth)acrylate, (2) radical polymerization initiator, (3) organic heat A composition containing expandable particles and (4) a particulate material, wherein (1) a composition containing 3 to 20 parts by mass of (1-4) an alkyl (meth)acrylate in 100 parts by mass of a polymerizable vinyl derivative. disclosed.

Further, in Patent Document 2, (1) (1-1) imide (meth)acrylate, (1-2) polyether-based urethane (meth)acrylate having a weight average molecular weight of 1,000 to 34,000, (1 -3) Polymerizable vinyl derivative containing polyfunctional (meth)acrylate other than (1-2), (2) radical polymerization initiator, (3) organic thermally expandable particles, and (4) particulate matter A composition for thin substrates is disclosed.

JP 2017-125178 A JP 2017-179125 A

However, the composition of Patent Document 1 is a two-part composition comprising a first agent containing a thermal radical polymerization initiator and a second agent containing a reducing agent. Mixing is required, and there are problems that the work is complicated and requires a long time for curing.

Moreover, the composition for a thin film substrate of Patent Document 2 has a low photocuring property, and it is necessary to irradiate the composition for a thin film substrate with ultraviolet rays each time a thin glass layer is laminated. have.

INDUSTRIAL APPLICABILITY The present invention is a one-liquid type composition for temporary fixing of thin glass, which is excellent in photocurability and can firmly temporarily fix thin glass to each other. To provide a composition for temporarily fixing a thin layer glass which can be easily peeled off in time.

The composition for temporarily fixing a thin layer glass of the present invention comprises an acrylic monofunctional monomer, a polyfunctional monomer, thermally expandable fine particles, and a photoradical polymerized polymer having a molar extinction coefficient ε at 400 nm of 100 L/(mol·cm) or more. Contains initiator.

[Acrylic Monofunctional Monomer]
The composition for thin-layer glass temporary fixing contains the acrylic monofunctional monomer. As the acrylic monofunctional monomer, (meth)acrylate is preferable because of its excellent photocurability. The (meth)acrylate is not particularly limited, and examples include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec- Butyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, Alkyl (meth)acrylates such as n-decyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)methacrylate, stearyl (meth)acrylate; isobornyl (meth)acrylate, norbornyl (meth)acrylate, tricyclononyl (meth)acrylate; ) acrylate, tricyclodecyl (meth)acrylate, tetracyclodecyl (meth)acrylate, cyclohexyl (meth)acrylate, tert-butylcyclohexyl (meth)acrylate, 3,5,5-trimethylcyclohexyl (meth)acrylate, dicyclopenta (meth)acrylates having an alicyclic skeleton such as nyl (meth)acrylate, dicyclopentenyl (meth)acrylate and adamantyl (meth)acrylate; having aromatic rings such as phenyl (meth)acrylate and benzyl (meth)acrylate ( meth) acrylate and the like. (Meth)acrylate means acrylate or methacrylate. The acrylic monofunctional monomers may be used alone or in combination of two or more.

In the present invention, the acrylic monofunctional monomer refers to a monomer having only one acryloyl group [CH ₂ =CHCO-] or methacryloyl group [CH ₂ =C(CH ₃ )CO-] in the molecule.

Since the acrylic monofunctional monomer can easily separate the thin glass sheets temporarily fixed via the thin glass temporary fixing composition one by one in a short time, the alkyl (meth)acrylate is used. preferably included. The alkyl group is an atomic group remaining after removing one hydrogen atom from an aliphatic saturated hydrocarbon. Hydrogens of alkyl groups are not replaced by other atoms or groups of atoms. The alkyl (meth)acrylate preferably does not have polyethylene oxide [--(O--CH ₂ CH ₂ )n--OH] having a terminal hydroxy group, which will be described later, in the molecule.

The number of carbon atoms in the alkyl group of the alkyl (meth)acrylate is preferably 1 or more, more preferably 4 or more, and more preferably 8 or more. The number of carbon atoms in the alkyl group of the alkyl (meth)acrylate is preferably 22 or less, more preferably 18 or less, and even more preferably 14 or less. When the number of carbon atoms in the alkyl group is 1 or more, the thin glass sheets temporarily fixed via the thin glass temporary fixing composition can be easily separated one by one in a short time, which is preferable. When the number of carbon atoms in the alkyl group is 22 or less, the composition for thin-layer glass temporary fixing is excellent in photocurability.

The content of the alkyl (meth)acrylate in the acrylic monofunctional monomer is preferably 20% by mass or more, more preferably 30% by mass or more, more preferably 35% by mass or more, and more preferably 40% by mass or more. The content of the alkyl (meth)acrylate in the acrylic monofunctional monomer is preferably 80% by mass or less, more preferably 70% by mass or less, more preferably 60% by mass or less, and more preferably 50% by mass or less. When the content of the alkyl (meth)acrylate is 20% by mass or more, the thin glass sheets temporarily fixed via the thin glass temporary fixing composition can be easily separated one by one in a short time. is possible and preferable. When the content of the alkyl (meth)acrylate is 80% by mass or less, the thin glass layers can be firmly temporarily fixed to each other, which is preferable.

It is preferable that the acrylic monofunctional monomer contains hydroxyalkyl (meth)acrylate because it can firmly temporarily fix the thin glass layers together. Hydroxyalkyl (meth)acrylate refers to (meth)acrylate in which one hydrogen of the alkyl group of alkyl (meth)acrylate is substituted with a hydroxy group (--OH). Hydroxyalkyl (meth)acrylates are not included in the category of alkyl (meth)acrylates because the hydrogen of the alkyl group is substituted with a hydroxy group.

Hydroxyalkyl (meth)acrylates include, for example, 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxy butyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 3-hydroxy-3-methylbutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3 -Hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate are preferred, and 2-hydroxyethyl (meth)acrylate is more preferred.

In the hydroxyalkyl (meth)acrylate, the number of carbon atoms in the alkyl group to which the hydroxy group is bonded is preferably 2 or more. In the hydroxyalkyl (meth)acrylate, the number of carbon atoms in the alkyl group to which the hydroxy group is bonded is preferably 4 or less. When the number of carbon atoms in the alkyl group to which the hydroxy group is bonded is 2 or more, the thin glass layers can be firmly temporarily fixed together, which is preferable. When the number of carbon atoms in the alkyl group to which the hydroxy group is bonded is 4 or less, the thin glass layers can be firmly temporarily fixed to each other, which is preferable.

The content of hydroxyalkyl (meth)acrylate in the acrylic monofunctional monomer is preferably 1% by mass or more, more preferably 3% by mass or more, and more preferably 5% by mass or more. The content of hydroxyalkyl (meth)acrylate in the acrylic monofunctional monomer is preferably 15% by mass or less, more preferably 12% by mass or less, and more preferably 10% by mass or less. When the content of the hydroxyalkyl (meth)acrylate is 1% by mass or more, the thin glass layers can be firmly temporarily fixed to each other, which is preferable. When the content of the hydroxyalkyl (meth)acrylate is 15% by mass or less, the thin glass sheets temporarily fixed via the thin glass temporary fixing composition can be easily separated one by one in a short time. It is possible and preferable.

Since the acrylic monofunctional monomer can firmly temporarily fix the thin glass layers, it preferably contains a (meth)acrylate having an alicyclic skeleton, and includes a (meth)acrylate having a polycyclic alicyclic skeleton. is more preferable. A (meth)acrylate having an alicyclic skeleton refers to a (meth)acrylate in which the alkyl group of an alkyl (meth)acrylate is substituted with an atomic group having an alicyclic skeleton.

An alicyclic skeleton is a hydrocarbon group that does not contain an aromatic ring structure, and includes a monocyclic alicyclic skeleton or a polycyclic alicyclic skeleton. Examples of the monocyclic alicyclic skeleton group include a cyclopentyl group and a cyclohexyl group. Examples of polycyclic alicyclic skeleton groups include a norbornyl group, an isobornyl group, a tricyclononyl group, a tricyclodecyl group, and a tetracyclododecyl group.

The content of (meth)acrylate having an alicyclic skeleton in the acrylic monofunctional monomer is preferably 5% by mass or more, more preferably 10% by mass or more, and more preferably 15% by mass or more. The content of (meth)acrylate having an alicyclic skeleton in the acrylic monofunctional monomer is preferably 50% by mass or less, more preferably 40% by mass or less, and more preferably 30% by mass or less. It is preferable that the content of the (meth)acrylate having an alicyclic skeleton is 5% by mass or more because the thin glass layers can be firmly temporarily fixed to each other. When the content of the (meth)acrylate having an alicyclic skeleton is 50% by mass or less, the thin glass sheets temporarily fixed via the thin glass temporary fixing composition can be easily formed into one sheet in a short time. It is preferable because it can be peeled off one by one.

The acrylic monofunctional monomer preferably contains an acrylic monofunctional monomer having polyethylene oxide with a terminal hydroxy group. An acrylic monofunctional monomer having polyethylene oxide having a terminal hydroxy group has polyethylene oxide [--(O--CH ₂ CH ₂ )n--OH] having a terminal hydroxy group in the molecule. n is a repeating unit and is a natural number. n is preferably 2 to 20 because the composition for temporarily fixing the thin glass has excellent photocurability and can firmly temporarily fix the thin glasses.

When the acrylic monofunctional monomer contains an acrylic monofunctional monomer having a polyoxyethylene oxide having a hydroxyl group at the end, the dispersibility of the thermally expandable fine particles in the composition for temporarily fixing thin-layer glass can be improved. The storage stability of the thin-layer glass temporary fixing composition is improved. Further, it is preferable that the thin glass temporary fixing composition contains an acrylic monofunctional monomer having polyethylene oxide having a hydroxyl group at the terminal, so that the thin glass can be firmly temporarily fixed to each other. Furthermore, the adhesiveness to thin glass can be improved due to the polyoxyethylene oxide having hydroxyl groups at the terminals.

The acrylic monofunctional monomer having polyethylene oxide having a hydroxyl group at its terminal is preferably an alkyl (meth)acrylate in which the hydrogen of the alkyl group is substituted with --(O-- _{CH.sub.2 CH.sub.2} )n--OH. Alkyl (meth)acrylates in which the hydrogen of the alkyl group is replaced with --(O--CH ₂ CH ₂ )n--OH are obtained by replacing the hydrogen of the alkyl group with --(O--CH ₂ CH ₂ )n--OH. Therefore, it is not included in the category of alkyl (meth)acrylates.

In the acrylic monofunctional monomer, the content of the acrylic monofunctional monomer having polyethylene oxide having a terminal hydroxyl group is preferably 1% by mass or more, more preferably 3% by mass or more, and more preferably 5% by mass or more. . In the acrylic monofunctional monomer, the content of the acrylic monofunctional monomer having polyethylene oxide having a terminal hydroxyl group is preferably 15% by mass or less, more preferably 12% by mass or less, and more preferably 10% by mass or less. . When the content of the acrylic monofunctional monomer having polyethylene oxide having a hydroxyl group at its end is 1% by mass or more, thin glass layers can be firmly temporarily fixed to each other, which is preferable. When the content of the acrylic monofunctional monomer having polyethylene oxide having a hydroxyl group at its end is 15% by mass or less, the thin glass sheets temporarily fixed to each other via the thin glass temporary fixing composition can be formed in a short time. It is preferable because it can be easily peeled off one by one.

The acrylic monofunctional monomer includes an acrylic monofunctional monomer having polyethylene oxide having a terminal hydroxy group, an alkyl (meth)acrylate, a hydroxyalkyl (meth)acrylate, and a (meth)acrylate having an alicyclic skeleton. is preferably contained. By containing a combination of these (meth)acrylates in the acrylic monofunctional monomer, the thin-layer glass temporary fixing composition has an excellent balance of photocurability, adhesiveness and peelability, and a thin layer While the glasses can be firmly temporarily fixed to each other, the thin-layer glasses temporarily fixed via the thin-layer glass temporary-fixing composition can be easily separated one by one in a short time.

Since the acrylic monofunctional monomer can firmly temporarily fix the thin glass layers together, it is preferable to include an alkyl (meth)acrylate having a carboxy group (-COOH) in the molecule. An alkyl (meth)acrylate having a carboxy group (-COOH) in the molecule refers to a (meth)acrylate in which one hydrogen atom of the alkyl group of the alkyl (meth)acrylate is substituted with an atomic group containing a carboxy group. Alkyl (meth)acrylates having a carboxy group in the molecule are not included in the category of alkyl (meth)acrylates because the hydrogen of the alkyl group is replaced with an atomic group containing a carboxy group.

Examples of alkylalkyl (meth)acrylates having a carboxy group in the molecule include β-carboxyethyl (meth)acrylate, 2-acryloyloxyethyl succinate, 2-acryloyloxyethyl phthalate, 2-acryloyloxy Examples include ethylhexahydrophthalic acid, and 2-acryloyloxyethylhexahydrophthalic acid is preferred. The alkylalkyl (meth)acrylates having a carboxy group in the molecule may be used alone or in combination of two or more.

The content of the alkylalkyl (meth)acrylate having a carboxy group in the molecule in the acrylic monofunctional monomer is preferably 1% by mass or more, more preferably 3% by mass or more, and more preferably 5% by mass or more. The content of the alkylalkyl (meth)acrylate having a carboxy group in the molecule in the acrylic monofunctional monomer is preferably 30% by mass or less, more preferably 25% by mass or less, and more preferably 20% by mass or less. When the content of the alkylalkyl (meth)acrylate having a carboxyl group in the molecule is 1% by mass or more, the thin glass layers can be firmly temporarily fixed together, which is preferable. When the content of the alkylalkyl (meth)acrylate having a carboxyl group in the molecule is 30% by mass or less, the thin glass sheets temporarily fixed to each other via the thin glass temporary fixing composition can be easily fixed in a short time. It is preferable that the sheets can be peeled off one by one.

[Polyfunctional monomer]
The composition for thin-layer glass temporary fixing contains the polyfunctional monomer. The polyfunctional monomer radically polymerizes with the acrylic monofunctional monomer to form a crosslinked structure, cure the composition for temporary fixing of thin layer glass, and allow the resulting cured product to exhibit adhesiveness.

In the present invention, a polyfunctional monomer refers to a monomer having a plurality of unsaturated double bonds in its molecule that can form a crosslinked structure by radical polymerization with the unsaturated double bond of an acrylic monofunctional monomer.

The polyfunctional monomer is not particularly limited as long as it can be radically polymerized with an acrylic monofunctional monomer to form a crosslinked structure. ) acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate , triethylene glycol di(meth)acrylate, decaethylene glycol di(meth)acrylate, pentadecaethylene glycol di(meth)acrylate, pentacontahectorethylene glycol di(meth)acrylate, pentaerythritol tetra(meth)acrylate, propylene glycol Di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, acrylic polyfunctional monomers such as allyl (meth) acrylate, aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene or derivatives thereof, and the like. , acrylic polyfunctional monomers are preferable because they are excellent in photocurability of the composition for temporary fixing of thin layer glass. In addition, a polyfunctional monomer may be used independently or 2 or more types may be used together.

The content of the polyfunctional monomer in the composition for temporarily fixing thin layer glass is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, more preferably 0.1 part by mass or more based on 100 parts by mass of the acrylic monofunctional monomer. 5 parts by mass or more is more preferable, and 0.8 parts by mass or more is more preferable. The content of the polyfunctional monomer in the composition for temporarily fixing thin layer glass is preferably 3 parts by mass or less, more preferably 2.5 parts by mass or less, and 2 parts by mass or less with respect to 100 parts by mass of the acrylic monofunctional monomer. is more preferable, and 1.5 parts by mass or less is more preferable. When the content of the polyfunctional monomer is 0.05 parts by mass or more, an appropriate crosslinked structure is imparted to the thin-layer glass temporary fixing composition, so that the thin-layer glasses can be firmly and temporarily fixed together by an appropriate cohesive force. On the other hand, when the thin glass is peeled off, the cured product of the composition for temporarily fixing the thin glass is easily peeled off from the thin glass in a sheet form due to the crosslinked structure contained in the cured product, and the thin layer Removes from the glass surface without sticky residue. When the content of the polyfunctional monomer is 3 parts by mass or less, the cured product of the thin-layer glass temporary fixing composition is prevented from becoming too hard, and the cured product does not pulverize from the surface of the thin-layer glass. It can be easily peeled off in a sheet form, and can be peeled off from the surface of the thin layer glass without leaving any sticky residue.

[Thermal expandable particles]
The thin-layer glass temporary fixing composition contains thermally expandable fine particles. Thermally expandable microparticles are microparticles that expand upon application of a predetermined amount of heat. At the time of processing the thin glass, the thin glass is laminated and integrated with each other through the cured product of the composition for temporary fixing of the thin glass to form a cured body, and after processing the cured body, the thin glass is separated from each other. peeled off. The composition for temporarily fixing the thin glass contains thermally expandable fine particles in order to reduce the adhesive strength of the cured product of the composition for temporarily fixing the thin glass when the thin glasses are separated from each other.

The thermally expandable fine particles are expanded by heating to reduce the adhesive force between the thin glass sheets by the cured product of the composition for temporarily fixing the thin layer glass, and the thin glass sheets in the laminated state after processing are formed one by one. It can be peeled off easily and without damage.

The thermally expandable fine particles are not particularly limited as long as they can be expanded by heating to reduce the adhesiveness of the cured product of the thin-layer glass temporary fixing composition. Examples of the thermally expandable fine particles include fine particles obtained by sealing a volatile expanding agent in hollow fine particles made of synthetic resin such as nitrile resin and olefin resin.

Fine particles made of synthetic resin in which a volatile expanding agent is enclosed in hollow fine particles are softened by heating, and the volume of the volatile expanding agent in the hollow fine particles is expanded by heating, thereby thermally expanding. It is configured. The volatile expansion agent inside the hollow fine particles in the thermally expandable fine particles is not released to the outside of the hollow fine particles when the thermally expandable fine particles are thermally expanded.

The nitrile-based resin contains nitrile-based monomer units. Nitrile monomers include, for example, acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethoxyacrylonitrile, fumaronitrile and the like. Incidentally, the nitrile-based monomers may be used alone or in combination of two or more.

The nitrile-based resin may contain monomer units other than nitrile-based monomer units. Examples of such monomers include vinyl chloride-based monomers such as vinylidene chloride; acrylates such as methyl acrylate, ethyl acrylate, butyl acrylate and dicyclopentenyl acrylate; methacrylate and the like. These monomers may be used alone or in combination of two or more.

A volatile expansion agent that volatilizes by heating is sealed in the hollow fine particles that constitute the thermally expandable fine particles. Volatile expanding agents include, for example, low molecular weight hydrocarbons such as ethane, ethylene, propane, propene, n-butane, isobutane, butene, isobutene, n-pentane, isopentane, neopentane, n-hexane, heptane, petroleum ether. chlorofluorocarbons such as CCL ₃ F, CCl ₂ F ₂ , CClF ₃ , CClF ₂ --CCl ₂ F ₂ ; tetraalkylsilanes such as tetramethylsilane, trimethylethylsilane, trimethylisopropylsilane and trimethyl-n-propylsilane; mentioned. The volatile swelling agents may be used alone or in combination of two or more.

The thermally expandable fine particles preferably contain first thermally expandable fine particles having a triple expansion temperature of 100°C or less and second thermally expandable fine particles having a triple expansion temperature of more than 100°C. By using two types of thermally expandable fine particles having different triple expansion temperatures, the first thermally expandable fine particles are thermally expanded first, and then the second thermally expandable fine particles are thermally expanded. can be done. In this manner, by shifting the timing of the start of thermal expansion of the first and second thermally expandable fine particles, the cured product of the composition for temporarily fixing the thin glass, which integrates the thin glasses, is gradually cured. can be thermally expanded to gradually reduce the adhesive strength. By gradually thermally expanding the cured product of the composition for temporarily fixing thin glass, the thin glass can be easily peeled off from each other without damage while reducing the stress applied to the thin glass.

The triple expansion temperature of the first thermally expandable fine particles is 100°C or lower, preferably 99°C or lower, and more preferably 98°C or lower. When the triple expansion temperature of the first thermally expandable fine particles is 100° C. or lower, the thin glass layers can be separated from each other while reducing the amount of heat applied to the thin glass layers.

The triple expansion temperature of the first thermally expandable fine particles is preferably 80°C or higher, more preferably 85°C or higher, and more preferably 90°C or higher. When the triple expansion temperature of the first thermally expandable fine particles is 80° C. or more, the thin glass layers can be easily separated without damaging each other.

The triple expansion temperature of the second thermally expandable fine particles exceeds 100°C. The triple expansion temperature of the second thermally expandable fine particles is preferably 101° C. or higher, more preferably 102° C. or higher, and even more preferably 103° C. or higher. When the triple expansion temperature of the second thermally expandable fine particles exceeds 100° C., the thin glass layers can be easily separated one by one while reducing the stress applied to the thin glass layers.

The triple expansion temperature of the second thermally expandable fine particles is preferably 120°C or lower, more preferably 115°C or lower, and more preferably 110°C or lower. When the triple expansion temperature of the second thermally expandable fine particles is 120° C. or lower, the thin glass layers can be separated from each other while reducing the amount of heat applied to the thin glass layers.

Here, the triple expansion temperature of the thermally expandable fine particles refers to the temperature at which the volume of the thermally expandable fine particles, when heated and expanded, becomes three times the volume before expansion. For example, when the radius of the thermally expandable fine particles before expansion is _D0 and the radius of the thermally expandable fine particles at the end of expansion is _D1 , the radius _D1 of the thermally expandable fine particles at the end of expansion is The temperature at which the radius D ₀ of the thermally expandable fine particles is multiplied by the “cubic root of 3” (approximately 1.44 times) can be used as a guideline. The radius of the thermally expandable fine particles means the radius of a true sphere having the same volume as the thermally expandable fine particles.

In the case of fine particles in which a volatile expanding agent is enclosed in hollow fine particles made of synthetic resin, the temperature at which the thermally expandable fine particles are three-fold expanded depends on the softening temperature of the synthetic resin forming the hollow fine particles and the shell of the hollow fine particles. By adjusting the thickness of the part and the amount of the volatile expanding agent sealed in the hollow fine particles, the triple expansion temperature of the thermally expandable fine particles can be adjusted.

Specifically, for example, by increasing (lowering) the softening temperature of the synthetic resin forming the hollow fine particles, the triple expansion temperature of the thermally expandable fine particles can be increased (lowered). By increasing (thinning) the thickness of the shell portion of the hollow fine particles, the triple expansion temperature of the thermally expandable fine particles can be increased (lowered). By increasing (decreasing) the amount of the volatile expanding agent sealed in the hollow microparticles, the triple expansion temperature of the thermally expandable microparticles can be lowered (higher). By increasing (lowering) the boiling point of the volatile expanding agent, the triple expansion temperature of the thermally expandable fine particles can be increased (lowered).

The average particle size of the thermally expandable fine particles is preferably 5 µm or more, more preferably 7 µm or more, and more preferably 10 µm or more. The average particle size of the thermally expandable fine particles is preferably 25 μm or less, more preferably 22 μm or less, more preferably 20 μm or less, and more preferably 18 μm or less. When the average particle size of the thermally expandable fine particles is 5 μm or more, the thin glass sheets temporarily fixed via the thin glass temporary fixing composition can be easily separated one by one in a short time. . When the average particle size of the thermally expandable fine particles is 25 μm or less, the thin glass can be easily peeled off one by one while reducing the stress applied to the thin glass. The average particle size of the thermally expandable fine particles refers to the 50% cumulative particle size in the volume-based particle size distribution according to the dynamic light scattering method.

The average particle size of the first thermally expandable fine particles is preferably 5 µm or more, more preferably 7 µm or more, and more preferably 10 µm or more. The average particle size of the first thermally expandable microparticles is more preferably 25 μm or less, more preferably 22 μm or less, more preferably 20 μm or less, and more preferably 18 μm or less. When the average particle size of the first heat-expandable fine particles is 5 μm or more, the thin glass sheets temporarily fixed via the thin glass temporary fixing composition can be easily separated one by one in a short time. can be done. When the average particle size of the first thermally expandable fine particles is 25 μm or less, the thin glass can be easily peeled off sheet by sheet while reducing the stress applied to the thin glass.

The average particle size of the second thermally expandable fine particles is preferably 5 µm or more, more preferably 7 µm or more, and more preferably 10 µm or more. The average particle size of the second thermally expandable microparticles is more preferably 25 μm or less, more preferably 22 μm or less, more preferably 20 μm or less, and more preferably 18 μm or less. When the average particle diameter of the second thermally expandable fine particles is 5 μm or more, the thin glass sheets temporarily fixed via the thin glass temporary fixing composition can be easily separated one by one in a short time. can be done. When the average particle diameter of the second thermally expandable fine particles is 25 μm or less, the thin glass can be easily peeled off one by one while reducing the stress applied to the thin glass.

The total content of the thermally expandable fine particles in the composition for temporarily fixing thin-layer glass is preferably 20 parts by mass or more, more preferably 25 parts by mass or more with respect to 100 parts by mass of the total content of the acrylic monofunctional monomer and the polyfunctional monomer. is more preferable, and 30 parts by mass or more is more preferable. The total content of thermally expandable fine particles in the composition for temporarily fixing thin-layer glass is preferably 40 parts by mass or less, and 35 parts by mass or less with respect to 100 parts by mass of the total content of acrylic monofunctional monomers and polyfunctional monomers. is more preferred. When the total content of the heat-expandable fine particles is 20 parts by mass or more, the adhesion strength of the cured composition for temporarily fixing the thin-layer glass that integrates the thin-layer glass is smoothly reduced, and the thin-layer glass is bonded. They can be easily separated from each other. When the total content of the thermally expandable fine particles is 40 parts by mass or less, the rapid expansion of the cured composition for temporarily fixing the thin glass, which integrates the thin glass, is suppressed, and the thin glass is unfavorable. The application of necessary stress can be reduced, and the thin glass layers can be peeled off from each other without damage.

When the thermally expandable fine particles contain the first thermally expandable fine particles and the second thermally expandable fine particles, the content of the first thermally expandable fine particles in the thermally expandable fine particles is preferably 30% by mass or more, and % by mass or more is more preferable, and 50% by mass or more is more preferable. The content of the first thermally expandable fine particles in the thermally expandable fine particles is preferably 80% by mass or less, more preferably 70% by mass or less. When the content of the first heat-expandable fine particles in the heat-expandable fine particles is 30% by mass or more, the adhesive strength of the cured composition for temporarily fixing the thin-layer glass, which integrates the thin-layer glasses, can be improved smoothly. By lowering it, the thin glass layers can be easily separated from each other. When the content of the first heat-expandable fine particles in the heat-expandable fine particles is 80% by mass or less, rapid expansion of the hardened composition for temporarily fixing the thin-layer glass that integrates the thin-layer glasses is suppressed. In addition, the application of unnecessary stress to the thin-layer glass can be reduced, and the thin-layer glass can be peeled off from each other without damage.

When the heat-expandable fine particles contain the first heat-expandable fine particles and the second heat-expandable fine particles, the content of the second heat-expandable fine particles in the heat-expandable fine particles is preferably 20% by mass or more, and 30% by mass. % or more by mass is more preferable. The content of the second thermally expandable fine particles in the thermally expandable fine particles is preferably 70% by mass or less, more preferably 60% by mass or less, and more preferably 50% by mass or less. When the content of the second heat-expandable fine particles in the heat-expandable fine particles is 20% by mass or more, rapid expansion of the hardened composition for temporarily fixing the thin-layer glass that integrates the thin-layer glasses is suppressed. In addition, the application of unnecessary stress to the thin-layer glass can be reduced, and the thin-layer glass can be peeled off from each other without damage. When the content of the second heat-expandable fine particles in the heat-expandable fine particles is 70% by mass or less, the adhesion strength of the cured composition for temporarily fixing the thin-layer glass, which integrates the thin-layer glasses, can be improved smoothly. By lowering it, the thin glass layers can be easily separated from each other.

In the heat-expandable fine particles, the total content of the first heat-expandable fine particles and the second heat-expandable fine particles is more preferably 85% by mass or more, more preferably 90% by mass or more, more preferably 95% by mass or more, 100% by mass is more preferred.

[Radical photopolymerization initiator]
The thin-layer glass temporary fixing composition contains a radical photopolymerization initiator having a molar extinction coefficient ε at 400 nm of 100 L/(mol·cm) or more. The molar extinction coefficient ε of the radical photopolymerization initiator at 400 nm is preferably 1500 L/(mol·cm) or less, more preferably 1000 L/(mol·cm) or less.

The molar extinction coefficient ε at 400 nm of the radical photopolymerization initiator is a value measured in the following manner. An acetonitrile solution is prepared by dissolving a photoradical polymerization initiator in acetonitrile. The prepared acetonitrile solution of a photoradical polymerization initiator is put into a cell having an optical path length B of 1 cm, and the absorbance A of the acetonitrile solution at 400 nm is measured using a spectrophotometer. At this time, the concentration c (mol/L) of the photoradical polymerization initiator in the acetonitrile solution is adjusted so that the absorbance A of the acetonitrile solution is 0.3 to 2.0. The molar extinction coefficient ε is calculated by the following formula (Lambert-Beer law). As the spectrophotometer, for example, a device commercially available from Shimadzu Corporation under the trade name “UV-3600” can be used.
A=ε×B×c
ε=A/(B×c)
ε: molar extinction coefficient [L/(mol cm)]
A: absorbance (no unit)
B: optical path length (cm)
c: Molar concentration (mol/L) of photoradical polymerization initiator in acetonitrile solution

A photoradical polymerization initiator generates radicals upon irradiation with curing light having a wavelength of 400 nm or more, and radically polymerizes monomers including acrylic monofunctional monomers and polyfunctional monomers.

The photoradical polymerization initiator can initiate radical polymerization of acrylic monofunctional monomers and polyfunctional monomers by irradiation with curing light having a wavelength of 400 nm or more. The composition for temporary fixing of the thin glass interposed between the thin glasses can be reliably photocured, and a plurality of sheets of the thin glass can be easily cured through the cured composition for temporarily fixing the thin glass. In addition, they can be smoothly laminated and integrated and temporarily fixed.

Furthermore, a laminate is formed by laminating a plurality of sheets of thin glass via a composition for temporary fixing of thin glass, and the laminated body is formed between the thin glasses and is used for temporary fixing of thin glass. The composition is irradiated with light to cure the multiple layers of the thin glass temporary fixing composition. On the other hand, the thin-layer glass temporary fixing composition contains thermally expandable fine particles and is cloudy.

Therefore, the thin-layer glass temporary fixing composition uses a photoradical polymerization initiator that generates radicals upon irradiation with curing light having a wavelength of 400 nm or more, and can radically polymerize acrylic monofunctional monomers and polyfunctional monomers. It is preferable to irradiate curing light having a wavelength of 400 nm or more as irradiation light for curing the thin layer glass temporary fixing composition. In this way, by using curing light with a wavelength of 400 nm or more as the irradiation light for curing the thin-layer glass temporary fixing composition, it is possible to prevent the thin-layer glass from being absorbed by the thin-layer glass. The fixing composition is sufficiently permeable, and the multiple layers of the thin layer glass temporary fixing composition are configured to be fully cured by one irradiation of light.

In a radical photopolymerization initiator having a molar extinction coefficient ε at 400 nm of 100 L/(mol·cm) or more, the wavelength of curing light irradiated to generate radicals is preferably 500 nm or less. When the wavelength of the curing light is 500 nm or less, the composition for thin layer glass temporary fixing is excellent in photocurability.

The photoradical polymerization initiator having a molar extinction coefficient ε of 100 L/(mol·cm) or more at 400 nm is not particularly limited. As the photo-radical polymerization initiator, for example, an acylphosphine oxide-based photo-radical polymerization initiator, a thioxanthone-based photo-radical polymerization initiator, and a triazine-based photo-radical polymerization initiator are preferable. Acylphosphine oxide-based radical photopolymerization initiators are more preferable because the workability of the thin-layer glass temporary fixing composition is excellent and the light-curing property of the thin-layer glass temporary fixing composition is excellent.

Examples of acylphosphine oxide photoradical polymerization initiators include 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

Examples of thioxanthone photoradical polymerization initiators include 2,4-diethylthioxanthone.

Triazine photoradical polymerization initiators include, for example, 2-[2-(furan-2-yl)vinyl]-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-[2- (5-methylfuran-2-yl)vinyl]-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-[(4-methoxyphenyl)vinyl]-4,6-bis(trichloro methyl)-1,3,5-triazine, 2-[(3,4-dimethoxyphenyl)vinyl]-4,6-bis(trichloromethyl)-1,3,5-triazine and the like.

In the thin-layer glass temporary fixing composition, the content of the photoradical polymerization initiator having a molar extinction coefficient ε at 400 nm of 100 L/(mol cm) or more is the total content of the acrylic monofunctional monomer and the polyfunctional monomer. It is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, and more preferably 0.3 parts by mass or more with respect to 100 parts by mass. In the thin-layer glass temporary fixing composition, the content of the photoradical polymerization initiator having a molar extinction coefficient ε at 400 nm of 100 L/(mol cm) or more is the total content of the acrylic monofunctional monomer and the polyfunctional monomer. It is preferably 5.0 parts by mass or less, more preferably 3.0 parts by mass or less, and more preferably 1.0 parts by mass or less based on 100 parts by mass. When the content of the photoradical polymerization initiator having a molar extinction coefficient ε at 400 nm of 100 L/(mol·cm) or more is 0.1 parts by mass or more, the composition for temporarily fixing a thin layer glass has excellent photocurability. preferred because When the content of the photoradical polymerization initiator having a molar extinction coefficient ε at 400 nm of 100 L/(mol·cm) or more is 5.0 parts by mass or less, the composition for temporarily fixing a thin layer glass has excellent photocurability. ing.

[Additive]
The thin-layer glass temporary fixing composition contains thixotropic agents, urethane acrylates, acrylic polymers, adhesion-imparting resins, plasticizers, non-thermally expansible fine particles, dyes, pigments, and flame retardants, as long as they do not interfere with the physical properties of the composition. , a silane coupling agent, a surfactant, and the like.

[Composition for temporary fixing of thin-layer glass]
The method for producing the thin-layer glass temporary fixing composition is not particularly limited. ) It can be produced by uniformly mixing the photoradical polymerization initiators described above in a general-purpose manner, preferably under reduced pressure.

[Processing method of thin glass]
The composition for temporary fixing of the thin glass is used for temporarily fixing the thin glass by superimposing the thin glass in the thickness direction thereof in a laminated state during processing of the thin glass. The thin-layer glass temporary fixing composition is suitably used for processing thin-layer glass, and can be particularly suitably used for processing thin-layer glass having a thickness of 200 μm or less. The thickness of the thin layer glass is preferably 30 μm or more.

An example of a thin-layer glass processing method using a thin-layer glass temporary fixing composition will be described. First, a laminate is produced by laminating a plurality of sheets of thin glass in the thickness direction with a thin glass temporary fixing composition interposed between the opposing surfaces of the thin glasses (lamination step ).

Since the thin-layer glass temporary fixing composition is a one-liquid type, it is possible to easily produce a laminate without the need for complicated work such as mixing two liquids when producing a laminate.

Next, the entire obtained laminate is irradiated with curing light having a wavelength of 400 nm or more from the lamination direction of the laminate (thickness direction of the thin layer glass), and a plurality of curing light interposed between the thin layers of glass in the laminate is irradiated. All the layers of the thin glass temporary fixing composition are cured to produce a cured product (curing step). The curing light may contain light having a wavelength of 400 nm or more. The thin glass sheets are temporarily fixed to each other by this cured product to produce a cured body in which a plurality of thin glass sheets are laminated and integrated by the cured product of the composition for temporary fixing of the thin glass. The peak wavelength of the curing light is preferably 500 nm or less because the composition for temporarily fixing a thin layer glass has excellent curability.

Curing light is irradiated in the stacking direction (thickness direction) of the laminate. Even a thin-layer glass temporary fixing composition in the form of a thin-layer glass is sufficiently permeable. The thin-layer glass temporary fixing composition contains a photoradical polymerization initiator capable of radically polymerizing acrylic monofunctional monomers and polyfunctional monomers by generating radicals by absorbing light having a wavelength of 400 nm or more. This photo-radical polymerization initiator effectively absorbs the curing light to facilitate the radical polymerization of the acrylic monofunctional monomer and polyfunctional monomer.

Furthermore, irradiation of the laminate with curing light does not need to be performed for each thin layer glass temporary fixing composition that exists in a plurality of layers. By irradiating with the curing light, all of the multiple layers of the composition for temporary fixing of the thin-layer glass interposed between the thin-layer glasses are irradiated with the curing light to surely cure the thin-layer glass in a short period of time. A cured body can be manufactured by temporarily fixing and integrating them.

In the laminated body, the thin glass layers are laminated and integrated by the cured product of the thin glass temporary fixing composition, and the overall mechanical strength is excellent. can be easily performed without damage (processing step).

After that, the cured body is heated to thermally expand the thermally expandable fine particles in the cured composition for temporarily fixing the thin layer glass, thereby reducing the adhesion strength of the cured body and causing the thin glass layers to separate from each other. , thin layer glass can be obtained one by one (peeling step).

When the thermally expandable fine particles contain the first thermally expandable fine particles and the second thermally expandable fine particles, the second thermally expandable fine particles are added after or during the first thermal expansion of the first thermally expandable fine particles. Thermally expands, the first thermally expandable fine particles and the second thermally expandable fine particles thermally expand with a time lag, gradually thermally expand the cured product of the composition for temporarily fixing a thin layer glass, and gradually reduce the adhesive strength. be able to. Therefore, application of excessive stress to the thin-layer glass can be reduced, and the thin-layer glass can be easily separated by peeling one sheet at a time without damage.

In addition, since the composition for temporarily fixing thin-layer glass has the above-described structure, adhesive residue is hardly left on the surface of the thin-layer glass, and the quality of the thin-layer glass can be ensured.

The method for heating the cured body is not particularly limited, and for example, the cured body is immersed in warm water, and the cured body is brought into contact with warm water to obtain a cured body (a cured body of a thin-layer glass temporary fixing composition ), and the like.

The temperature of the hot water is preferably between the triple expansion temperature of the first thermally expandable fine particles and the triple expansion temperature of the second thermally expandable fine particles. The first heat-expandable fine particles and the second heat-expandable fine particles thermally expand with a time difference, and the thin-layer glass is separated from each other without damage by reducing the adhesiveness of the cured product without applying almost any stress to the thin-layer glass. can do.

Since the composition for temporarily fixing thin-layer glass of the present invention has the structure as described above, it is excellent in photocurability and can temporarily fix thin-layer glasses to each other regardless of the stress during processing. After processing the layer glass, the thin layer glasses can be easily separated in a short time without damage.

FIG. 4 is a cross-sectional view showing a procedure for measuring adhesive strength; It is the top view which showed the measuring point of adhesive strength.

The present invention will be described in more detail below using examples, but the present invention is not limited to these.

The following compounds were used in Examples and Comparative Examples.

[Acrylic Monofunctional Monomer]
・Isobornyl methacrylate ・Isodecyl methacrylate ・2-Hydroxyethyl methacrylate ・2-Acryloyloxyethyl hexahydrophthalic acid (trade name “Light acrylate HOA-HH” manufactured by Kyoeisha Chemical Co., Ltd.)
・Acrylic monofunctional monomer having a polyethylene oxide having a hydroxyl group at the end (POE acrylic monofunctional monomer 1, trade name “Blenmer AE-400” manufactured by NOF Corporation)
・Acrylic monofunctional monomer having a polyethylene oxide having a hydroxyl group at the end (POE acrylic monofunctional monomer 2, trade name “Blenmer AE-200” manufactured by NOF Corporation)

[Polyfunctional monomer]
・1,6-hexanediol dimethacrylate

[Thermal expandable particles]
・First thermally expandable microparticles (3-fold expansion temperature: 98°C, average particle size: 13 µm, acrylonitrile copolymer)
・Second thermally expandable fine particles (triple expansion temperature: 105 ° C., average particle size: 14 μm, vinylidene chloride-acrylonitrile copolymer)

[Radical photopolymerization initiator]
- Photoradical polymerization initiator 1 [2,4,6-trimethylbenzoyldiphenylphosphine oxide, IGM Resins B.I. V. Company product name “Omnirad TPO H”, molar extinction coefficient ε at 400 nm: 349 L / (mol cm)]
Photoradical polymerization initiator 2 [1-hydroxycyclohexyl-phenylketone, IGM Resins B.I. V. Company trade name “Omnirad 184”, molar extinction coefficient ε at 400 nm: 0 L / (mol cm)]

The molar extinction coefficient ε of photoradical polymerization initiator 1 was measured in the following manner. 9.7 mg (2.78×10 ⁻⁵ mol) of radical photopolymerization initiator 1 was weighed and dissolved in 9.7547 g (12.506 mL) of acetonitrile (density: 0.78 g/mL). The concentration c of photoradical polymerization initiator 1 was 0.00233 (mol/L). The absorbance A at 400 nm of the acetonitrile solution was 0.754. As a result of calculating the molar extinction coefficient ε using the above formula (Lambert-Beer's law), the molar extinction coefficient ε of the radical photopolymerization initiator 1 was 349 L/(mol·cm).

[Thixotropic agent]
・ Hydrophobic fumed silica (trade name “AEROSIL R972” manufactured by Evonik)

(Examples 1 to 9, Comparative Examples 1 and 2)
Predetermined amounts of acrylic monofunctional monomers and polyfunctional monomers shown in Table 1 were respectively fed into a reaction vessel made of polypropylene, mixed and dissolved to prepare a mixed solution.

Next, the mixture in the reaction vessel is stirred at a rotation speed of 1000 rpm using a stirrer (trade name "BL-300D" manufactured by AS ONE, stirring blade: disper blade used), and a thixotropic mixture is added to the mixture. A predetermined amount of hydrophobic fumed silica as an agent shown in Table 1 was supplied and stirred for 30 minutes to disperse the thixotropic agent in the mixture.

Next, the mixed liquid in the reaction container is supplied to a decompressible decompression container (trade name "Vacuum Oven: VOS-310C" manufactured by Tokyo Rika Kikai Co., Ltd.) and subjected to decompression treatment at 25°C for 30 minutes (vacuum pump : DTC-22 (manufactured by ULVAC KIKO)) to degas the mixed liquid.

Thereafter, the first heat-expandable fine particles, the second heat-expandable fine particles, and a photoradical polymerization initiator are supplied to the mixed liquid, and the first heat-expandable fine particles and the second heat-expandable fine particles are uniformly dispersed and The mixture was mixed until the radical photopolymerization initiator was completely dissolved in the mixed liquid to obtain a composition for temporary fixing of thin layer glass. The obtained composition for temporary fixing of thin-layer glass was an opaque white liquid.

For the obtained composition for temporary fixing of thin-layer glass, the thin-layer glass fixing confirmation test, adhesive strength, peeling test and storage stability were measured in the following manner, and the results are shown in Table 1.

[Thin-layer glass fixation confirmation test]
A lower protective glass plate having a length of 100 mm, a width of 50 mm, and a thickness of 0.5 mm was prepared. A thin-layer glass temporary fixing composition was placed on the central portion of the protective glass plate. A thin layer glass having a length of 100 mm, a width of 50 mm, and a thickness of 0.1 mm is placed on the thin layer glass temporary fixing composition, and a thin layer is placed between the opposing surfaces of the thin layer glass and the lower protective glass plate facing it. The composition for temporary fixing of layer glass was completely filled. The thickness of the thin-layer glass temporary fixing composition was 50 μm.

Next, a thin-layer glass temporary fixing composition was placed on the center of the upper surface of the thin-layer glass. A thin layer glass having a length of 100 mm, a width of 50 mm, and a thickness of 0.1 mm is placed on the thin layer glass temporary fixing composition, and the thin layer glass temporary fixing composition is placed between the opposing surfaces of the two thin layer glasses. It was left completely filled. The thickness of the thin-layer glass temporary fixing composition was 50 µm.

The above procedure of stacking the thin-layer glasses was repeated, and five thin-layer glasses were laminated on the lower protective glass plate via the composition for temporary fixing of the thin-layer glass to produce a laminate. Furthermore, the composition for temporary fixing of thin glass was placed on the center of the top surface of the uppermost thin glass among the five laminated thin glasses. An upper protective glass plate having a length of 100 mm, a width of 50 mm, and a thickness of 0.5 mm is placed on the thin-layer glass temporary fixing composition, and the thin-layer glass is placed between the facing surfaces of the upper protective glass plate facing the thin-layer glass. The composition for temporary fixing of thin layer glass was completely filled. The thickness of the thin-layer glass temporary fixing composition was 50 μm.

Using a visible light lamp (trade name “FL-V” manufactured by Sekisui Fuller Co., Ltd.) ^, the laminate was irradiated with visible light having a peak wavelength of 420 nm at an illuminance of 2 mW / cm for 10 minutes to form a thin layer. A cured body was produced by curing the composition for glass temporary fixing. The visible light lamp was placed vertically above the laminate and at a height of 80 mm from the mounting surface on which the lower protective glass plate was mounted.

The uppermost layer of thin glass in the obtained cured product is touched with a fingertip and moved horizontally to determine whether or not the thin layers of glass are integrated with each other by the cured product of the composition for temporary fixing of thin layer glass. confirmed.

"A" if the thin glass sheets are integrated between all adjacent thin glass sheets, and "A" if the thin glass sheets are not integrated between any of the adjacent thin glass sheets. It was evaluated as "B".

[Adhesion strength]
Two sheets of plate glass 1 and 2 each having a rectangular parallelepiped shape of 50 mm long×25 mm wide×5 mm thick were prepared. The entire surfaces of the two plate glasses were washed with ethanol and dried.

As shown in FIGS. 1 and 2, one glass plate 1 is placed on a horizontal mounting surface 3, and a long side of the other glass plate 2 is placed on the edge of the long side of the glass plate 1. were overlapped. The overlapping width between the edge portions of the two sheet glasses 1 and 2 was 12.5 mm. A thin-layer glass temporary fixing composition 5 is interposed between the edges of the long sides of the two plate glasses 1 and 2, and the thin-layer glass temporary fixing composition 5 is applied to the two plate glasses 1 and 2. 2, the entire length in the horizontal direction between the facing surfaces of the end edges on the long sides was filled. The thin layer glass temporary fixing composition 5 had a length of 25 mm, a width of 12.5 mm, and a thickness of 0.1 mm. A support plate glass 4 was arranged in a gap between the plate glass superimposed on the upper side and the mounting surface, and the upper plate glass 2 was supported by the support plate glass 4 .

A visible light lamp (manufactured by Sekisui Fuller Co., Ltd., trade name “FL-V”) was used on the thin-layer glass temporary fixing composition 5 interposed in the overlapping portion of the two sheet glasses 1 and 2, and the peak wavelength was 420 nm. The composition 5 for temporary fixing of the thin layer glass was cured by irradiating it with visible light at an illuminance of 2 mW/cm ² for 10 minutes to prepare a cured body. The visible light lamp was placed vertically above the overlapped portion of the two plate glasses and at a height of 80 mm from the mounting surface.

The resulting hardened body is subjected to a three-point bending test using a desktop precision universal testing machine (manufactured by Shimadzu Corporation, trade name "Autograph AGS-100NX"), and two sheets of glass are superimposed at an indentation speed of 10 mm / min. The maximum strength obtained by pressing the part was used as the measured strength (N), the peel strength was calculated based on the following formula, and the failure mode was evaluated according to the following criteria.

Comparative Example 2 could not be evaluated because the thin-layer glass temporary fixing composition did not harden.

(Peel strength)
Peel strength (N/mm ² ) = measured strength (N)/(25 x 12.5) (mm ² )

(destruction mode)
MF: Material failure (Although the plate glass cracked, interfacial peeling between the plate glass and the cured product and cohesive failure of the cured product did not occur.)
CF: Cohesive failure (cohesive failure of the cured product occurred.)
AF: Interfacial failure (Interfacial peeling occurred between the plate glass and the cured product.)

[Peeling test]
The hardened body prepared in the thin-layer glass fixation confirmation test was immersed in warm water maintained at 95°C. The peeling time (seconds) from immediately after the cured body was immersed in warm water until the five sheets of thin glass were peeled off one by one was measured.

The five sheets of thin-layer glass after peeling were observed, and the thin-layer glass was visually observed for damage and adhesion (adhesive residue) of the cured product of the thin-layer glass temporary fixing composition. Comparative Example 2 could not be evaluated because the thin-layer glass temporary fixing composition was not cured.

(Presence or absence of damage to thin-layer glass)
A: No damage was found on any of the thin-layer glasses.
B: There was thin-layer glass with the corner part hanging.
C: There was crushed thin layer glass.
D: The thin layer glass could not be peeled off with warm water.
E: The thin-layer glass temporary fixing composition did not cure.

(adhesive residue)
The area of the adhesive residue remaining on both sides of each thin-layer glass was measured, and the total area _S1 of the adhesive residue of the five thin-layer glasses was calculated. The total area of both surfaces of the five sheets of thin glass was defined as S ₀ . The degree of adhesive residue was calculated based on the following formula and evaluated based on the following criteria.
Adhesive residue degree (%) = 100 x _S1 / _S0

A: The degree of adhesive residue was 0%.
B: The degree of adhesive residue exceeded 0% and was 5% or less.
C: The degree of adhesive residue exceeded 5%.
D: The thin layer glass could not be peeled off with warm water.
E: The thin-layer glass temporary fixing composition did not cure.

[Storage stability]
15 mL of the composition for temporary fixing of thin layer glass was supplied to a transparent 20 mL glass vial and left at 25° C. in a dark place where the liquid would not be shaken by vibration or the like. After 2 days and 7 days from standing, the state of the composition for temporary fixing of thin layer glass was visually observed and evaluated based on the following criteria.

A: The thermally expandable fine particles were uniformly dispersed in the composition for temporarily fixing the thin layer glass, and no separation or sedimentation of the thermally expandable fine particles could be confirmed.
B: In the composition for temporarily fixing thin-layer glass, the thermally expandable fine particles are separated or sedimented, and the thermally expandable fine particles cannot be dispersed in less than 50% by volume of the composition for temporarily fixing thin-layer glass. there was a spot. Re-dispersion was possible by stirring and shaking the thin layer glass temporary fixing composition.
C: In the composition for thin-layer glass temporary fixing, the thermally expandable fine particles are separated or sedimented, and the thermally expandable fine particles cannot be dispersed in 50% by volume or more of the composition for thin-layer glass temporary fixing. there was a spot. Even if the thin-layer glass temporary fixing composition was stirred and shaken, the thermally expandable fine particles could not be redispersed.
D: Thermally expandable fine particles were not contained in the thin-layer glass temporary fixing composition, and the storage stability could not be evaluated.

The composition for temporarily fixing thin-layer glass of the present invention can temporarily fix thin-layer glasses and process the thin-layer glasses without causing separation between the thin-layer glasses.

The thin-layer glass temporary fixing composition of the present invention can easily separate the thin-layer glasses in a short time without damaging them after processing the thin-layer glasses.

(Cross reference to related applications)
This application claims priority based on Japanese Patent Application No. 2021-091954 filed on May 31, 2021, and the disclosure of this application is incorporated herein by reference in its entirety. .

1 Sheet glass 2 Sheet glass 3 Mounting surface 4 Supporting sheet glass 5 Composition for temporary fixing of thin layer glass

Claims (6)

1. A thin-layer glass temporary characterized by comprising an acrylic monofunctional monomer, a multifunctional monomer, thermally expandable fine particles, and a photoradical polymerization initiator having a molar extinction coefficient ε at 400 nm of 100 L/(mol cm) or more. Fixing composition.
2. A claim characterized in that the thermally expandable fine particles contain first thermally expandable fine particles having a triple expansion temperature of 100°C or less and second thermally expandable fine particles having a triple expansion temperature of over 100°C. Item 1. The composition for temporarily fixing thin layer glass according to item 1.
3. The composition for temporarily fixing a thin layer glass according to claim 1 or claim 2, wherein the acrylic monofunctional monomer contains an acrylic monofunctional monomer having polyethylene oxide having a hydroxyl group at its end.
4. The composition for temporarily fixing a thin layer glass according to claim 1 or claim 2, characterized by containing 20 to 40 parts by mass of thermally expandable fine particles with respect to 100 parts by mass of an acrylic monofunctional monomer.
5. The composition for temporarily fixing a thin layer glass according to claim 2, wherein the content of the first thermally expandable fine particles in the thermally expandable fine particles is 30 to 80% by mass.
6. A lamination step of laminating a plurality of sheets of thin glass via the thin glass temporary fixing composition of claim 1 or claim 2 to produce a laminated body;
   The laminate is irradiated with curing light having a wavelength of 400 nm or more to cure the thin-layer glass temporary fixing composition to produce a cured product, and the plurality of thin-layer glasses are temporarily fixed together by the cured product. A curing step for producing a cured body,
   a processing step of processing the thin layer glass of the cured body;
   and a peeling step of heating the cured body to expand the thermally expandable fine particles to separate the thin glasses.

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