JP4858481B2 - Composition for producing foam and foam obtained using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a foaming composition that can produce a foam excellent in molding processability such as thin material formation and lamination, and having fine bubbles, a method for producing the foam using it, and a composition for producing the foam having a high environment maintainability that can maintain the foamed (porous) structure without disappearing the fine bubbles even on leaving it under a high humidity environment. <P>SOLUTION: The composition for producing the foam is characterized by containing an acid-generating agent for generating an acid or a base-generating agent for generating a base by the action of an active energy beam, and further a compound having a decomposable foaming functional group to decompose and release equal to or more than one kind of low-boiling volatile compound by reacting with the acid or base. The decomposable foaming compound is selected from (1) a film-forming polymer and (2) a monomer polymerizing by an irradiation of the active energy beam to form the film-forming polymer. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a foam in which a plurality of independent and / or continuous cells are formed, and a composition for producing a foam used therefor. More specifically, the present invention relates to a composition for producing a foam that is excellent in molding processability such as thin film formation and lamination and that forms microbubbles, and a foam obtained by using the composition. Furthermore, the present invention relates to a composition for producing a foam that is excellent in environmental preservation, in which the formed microbubbles do not disappear in a high humidity environment. The composition for producing a foam according to the present invention is useful as a raw material for producing a foam that is required to have high heat insulating properties, light weight, buffer properties, low dielectric constant properties, light scattering properties, and the like.

About Foams Conventional foams are often made of organic materials such as urethane foam, styrene foam, and foamed polyethylene, but those made of inorganic materials such as porous ceramics and porous glass have also been reported. Many foams made of an organic material utilize foamed plastics based on a polymer material, and take advantage of the property that the polymer material is liquid at the time of foaming and has an appropriate viscosity (for example, “ Foam / Porous Material Technology and Application Development (Author: Toray Research Center, 1996) ”: Non-Patent Document 1 or“ Resin Foam Molding Technology (Author: Technical Information Association, 2001) ”: Refer to Non-Patent Document 2 .)

Regarding the foaming method Most of the typical methods for producing foam plastics include a method in which a foaming agent is mixed in a polymer material. 11-238112: see Patent Document 1), and a method using phase separation generated from a difference in crosslink density of a polymer material (for example, see Japanese Patent Laid-Open No. 10-504582: see Patent Document 2). It has been. Regarding the method of incorporating a foaming agent, a great number of reports have been made, and roughly classified into chemical foaming agents and physical foaming agents.

About chemical blowing agents Chemical blowing agents include azo compounds represented by azodicarbonamide and azobisisobutyronitrile, sulfonyl hydrazide compounds represented by p, p'-oxybisbenzenesulfonyl hydrazide and the like. These are organic compounds that are thermally decomposed to release one or more gases such as nitrogen and carbon dioxide. These chemical blowing agents can be kneaded or dissolved in a softened polymer in a temperature range below the decomposition temperature, and then heated to a temperature range above the decomposition temperature to be foamed. (For example, Japanese Patent Application Laid-Open No. 5-212811: Patent Document 3, Japanese Patent Application Laid-Open No. 6-126851: Patent Document 4, Japanese Patent Application Laid-Open No. 6-145400: Patent Document 5 or Japanese Patent Application Laid-Open No. 9-132661: Patent Document. 6). Such a chemical foaming agent is used in combination with a foaming aid, a crosslinking agent, a stabilizer, etc., as necessary, when foaming the chemical foaming agent. An organic compound that generates a gas in the course of polymer polymerization is also included in the chemical foaming agent, and a typical example thereof is polyurethane foam. Polyurethane is a polymer of a polyol (an oligomer having two or more —OH groups which are alcoholic hydroxyl groups) and a polyisocyanate (a compound having two or more —NCO groups which are isocyanate groups in the molecule). In the process, CO ₂ gas is generated to form a foam (see, for example, JP-A-7-258451: Patent Document 7).

About physical foaming agents Physical foaming agents include low boiling point volatile substances such as volatile saturated hydrocarbons such as butane and pentane, and volatile fluorocarbons such as fluoroethane. Examples include substances. As the physical foaming agent, a low boiling point volatile substance that is a liquid at room temperature but volatilizes at 50 to 100 ° C. and becomes a gas is often used, and these are contained in a polymer material at a temperature below the boiling point. A foam can be formed by impregnating and heating it above the boiling point of the physical foaming agent (for example, JP-A-6-107842: Patent Document 8 or JP-A-6-254882): Patent Reference 9). Also known is a capsule-shaped foaming agent produced by sealing a low-boiling volatile substance in a thermoplastic polymer material as an outer shell (for example, JP-A-7-173320: Patent Document) 10 or Japanese Patent Application Laid-Open No. 2000-024488: Patent Document 11.).
Also, an inert gas that is in a gaseous state at normal temperature and pressure, such as carbon dioxide and nitrogen, can be used as a physical foaming agent. In this case, an inert gas in a gaseous state is dissolved in a polymer material in a molten state controlled to an appropriate pressure and temperature, and then this mixed system is released to a normal temperature and normal pressure state, thereby obtaining a liquid. The phase substance is rapidly vaporized and expanded to obtain a foam (for example, JP-A-5-230259: Patent Document 12, JP-A-7-196835: Patent Document 13 or JP-A-7-330940). Gazette: see Patent Document 14.).

Uses of foams The properties of foams produced by various methods include heat insulation function, cushioning and cushioning function, light weight and levitation function, vibration absorption function, etc., when it has closed cells. These useful properties are used in a wide range of fields such as refrigerators, building materials, food trays, thermal recording paper, packaging materials, surfboards, and audio equipment. Further, when the foam has open cells, the surface area is remarkably increased, and therefore, an adsorption function and a storage function, a support function and a catalyst function, a permeation function and a filtration function, etc. are expressed with respect to the gas material or the liquid material. Used for household sponges and medical separation membranes.

Problems with foams Even foams with many superior functions do not meet all requirements. One of the drawbacks of conventional foam plastics is a reduction in mechanical strength. This phenomenon is mainly caused by bubbles becoming internal defects of the material itself, and tends to have insufficient durability and crack resistance. For example, in the field of thermal recording materials, the loss of thermal energy required for a recorded image can be suppressed by using a foam sheet with a heat insulating function provided on the support of the recording material, which has a great effect on improving the sensitivity. . However, since the foam sheet has a weak surface hardness, there are problems that the surface of the recording material is likely to be damaged and cracks are likely to occur.

Bubble miniaturization and problems of microcellular plastics In recent years, it has been devised to miniaturize a bubble as a means for suppressing a decrease in mechanical strength of a foam. Specifically, a material called microcellular plastic, which has a bubble diameter of 0.1 to 10 μm and a bubble density of 10 ⁹ to 10 ¹⁵ pieces / cm ³ , is manufactured by N. Massachusetts Institute of Technology. P. Suh et al. (See, for example, US Pat. No. 4,473,665: Patent Document 15). For the formation of this microcellular plastic, a method using an inert gas such as carbon dioxide or nitrogen as a physical foaming agent is employed. Specifically, after impregnating an inert gas into a supersaturated state in a supercritical state under a high pressure to a supersaturated state, the gas supersaturated plastic is decompressed and heated to obtain a microcellular plastic. In general, the larger the impregnation amount of the inert gas, the smaller the bubble diameter and the higher the bubble density. On the other hand, the impregnation amount is longer until the impregnation amount reaches saturation. It has the problem of taking time. For example, it has been reported that several days are required to impregnate and saturate carbon dioxide in polyethylene terephthalate, and the poor production efficiency is a problem.

Problems with Thinning of Foams Molding of plastic foams uses batch, extrusion, and injection molding processes, as well as conventional plastics. Various processes such as lumps, pellets, and sheets are used. Expandable plastic materials having various shapes and sizes are commercially available. In recent years, as typified by mobile phones and personal computer devices that have been making efforts to reduce weight, there has been a strong demand for weight reduction and thinning of materials for next generation in various fields. A wave of demand is raging. However, it is very difficult to produce a thin foam by the conventional molding process. In particular, a process suitable for microcellular plastics proposed as a means for preventing a decrease in mechanical strength has not yet been established. The reason is that a plastic impregnated with gas in a high pressure state is molded at normal pressure while extruding it with a molding machine such as a die, so that part of the gas impregnated in the plastic is diffused before foaming. The phenomenon is known. The thinner the molded body is, the greater the amount of gas diffused. In particular, when the thickness of the molded body is 50 μm or less, poor foaming due to outgassing tends to occur. For these reasons, it is considered extremely difficult to produce a thin foam having microbubbles.

Water resistance / moisture-resistant storage of foam If the foam is made of a polymer material with high hygroscopicity and water absorption, if the foam is left in a high humidity environment, the foam will gradually permeate and adsorb moisture. Therefore, the dimensional change (expansion or contraction) of the foam and the disappearance of the foam structure (porous structure) are likely to occur. Such foams have insufficient foaming characteristics, so that the use environment conditions are restricted, and the application development is difficult. Therefore, it is important to improve the water- and moisture-resistant storage stability of the foam, and many such solutions have been reported. As a report example, there is a method (physical hydrophobization treatment method) in which water resistance is improved by spraying and adsorbing hydrophobic fine particles on the foam surface (for example, JP 2001-92467 A: Patent Document 16). reference.). In addition, there is a chemical method (chemical hydrophobization treatment method) in which moisture resistance is improved by reacting a hydrophilic porous airgel with a compound having a hydrophobic functional group (for example, JP-A-20002000). -264620 gazette: see Patent Document 17.).
JP 11-238112 A JP-A-10-504582 Japanese Patent Laid-Open No. 5-212811 Japanese Patent Laid-Open No. 6-125851 JP-A-6-145400 JP-A-9-132661 JP 7-258451 A JP-A-6-107842 Japanese Patent Laid-Open No. 6-254982 JP-A-7-173320 JP 2000-024488 A Japanese Patent Laid-Open No. 5-230259 JP-A-7-196835 JP-A-7-330940 U.S. Pat. No. 4,473,665 JP 2001-92467 A JP 2000-264620 A "Foam and porous material technology and application development (Author: Toray Research Center, 1996)" "Resin foaming technology (Author: Technical Information Association, 2001)"

  The present invention seeks to provide a composition for producing a foam which is excellent in molding processability such as thinning and lamination, and which can produce a foam having microbubbles, and a foam obtained using the same. Is. Further, the present invention is intended to provide a composition for producing a foam having high environmental preservation and capable of maintaining a foamed (porous) structure without causing the formed microbubbles to disappear even when left in a high humidity environment. is there.

Foamable composition (1)
The composition for producing a foam of the present invention includes an acid generator that generates an acid by the action of active energy rays or a base generator that generates a base, and further reacts with an acid or a base to produce one or more low boiling points. A decomposable compound that decomposes and desorbs volatile substances, and the decomposable foamable compound comprises:
1. 1. a film-forming polymer, and It is selected from monomers that form a film-forming polymer by polymerization upon irradiation with active energy rays. Hereinafter, it is described as a foamable composition (1).

Foamable composition (2)
The composition for producing a foam according to the present invention is a compound in which the decomposable foamable compound of the foamable composition (1) is obtained by introducing the decomposable foamable functional group into a compound containing at least one kind of hydrophobic functional group. It is characterized by being. Hereinafter, it is described as a foamable composition (2). The compound containing a hydrophobic functional group is a compound having a characteristic that moisture adsorption hardly occurs and performance deterioration (disappearance of foamed structure) due to moisture hardly occurs.

Foamable composition (3)
The composition for producing a foam of the present invention is characterized in that the decomposable foamable compound of the foamable composition (1) is a compound obtained by introducing the decomposable foamable functional group into a low hygroscopic compound. In addition, the equilibrium water absorption of the low hygroscopic compound is less than 10% when measured by the JISK7209D method in an environmental atmosphere at a temperature of 30 ° C. and a relative humidity of 60%. Hereinafter, it is described as a foamable composition (3).

Method for producing foam (A)
In the production method (A) for obtaining the foam of the present invention, a coating liquid containing any of the foamable composition (1), (2) or (3) of the present invention is applied on a support. The coating layer is formed, and the coating layer is irradiated with an active energy ray and further subjected to a heat treatment to form a foamed structure in the coating layer. Hereinafter, it is referred to as a foam production method (A).

Foamable composition (4)
The foamable composition (4) of the reference invention includes an acid generator that generates an acid by the action of active energy rays or a base generator that generates a base, and further reacts with an acid or a base to produce one or more low-grade compositions. It includes a compound having decomposition foaming property that decomposes and desorbs boiling-point volatile substances, and the decomposition foaming compound is selected from monomers that are not polymerized and cured by irradiation with active energy rays. Hereinafter, it is described as a foamable composition (4).

Method for producing foam (B)
In the foam production method (B), a coating solution containing the foamable composition (4) of the reference invention and a film-forming resin is coated on a support to form a coating layer. The coating layer is dried and solidified by irradiating active energy rays and further subjected to heat treatment, and a foam structure is formed therein. Hereinafter, it is referred to as a foam production method (B).

  A decomposable compound containing an acid generator that generates an acid by the action of active energy rays or a base generator that generates a base, and further decomposes and desorbs one or more low-boiling volatile compounds by reacting with the acid or base By using a composition for producing a foam containing the above, it has become possible to produce a foam having a thin substance and microbubbles. In addition, the microbubbles formed by the above production method can retain a foamed (porous) structure without disappearing even when left in a high humidity environment.

  The composition for producing a foam of the present invention (hereinafter sometimes referred to as “foamable composition”) is a composition comprising the following two components. One of them is an acid generator that generates an acid by the action of an active energy ray, or a base generator that generates a base, and the other is one or more types that react with the generated acid or base. It is a decomposition foamable compound that decomposes and desorbs low boiling point volatile compounds.

The decomposition foamable compound contained in the foamable composition (1) of the present invention is:
1. 1. a film-forming polymer, and It is selected from monomers that form a film-forming polymer by polymerization upon irradiation with active energy rays.
Therefore, if a coating liquid containing the foamable composition (1) of the present invention is applied onto a support, and this is sequentially subjected to active energy ray irradiation and heat treatment, the coating liquid layer is solidified and contained therein. A foam structure (porous structure) can be formed.

The decomposable foamable compound contained in the foamable composition (2) of the present invention is a compound obtained by introducing the decomposable foamable functional group into a compound containing at least one kind of hydrophobic functional group.
Therefore, if a coating liquid containing the foamable composition (2) of the present invention is applied onto a support, and this is subjected to active energy ray irradiation and heat treatment in sequence, the coating liquid layer is solidified, A foam structure (porous structure) can be formed. Furthermore, by having a hydrophobic compound, the foamed structure can be retained even when left in a high humidity environment.

The foamable composition (3) of the present invention is a compound in which the decomposition foamable functional group is introduced into a low hygroscopic compound, and the equilibrium water absorption rate of the low hygroscopic compound is 30 ° C. and relative humidity 60%. It is less than 10% when measured by the JISK7209D method in an environmental atmosphere.
Therefore, if a coating liquid containing the foamable composition (3) of the present invention is applied onto a support, and this is subjected to active energy ray irradiation and heat treatment in sequence, the coating liquid layer is solidified, A foam structure (porous structure) can be formed. Furthermore, since the composition of the coating layer having a foam structure has a low hygroscopic property, the foam structure can be retained even when left in a high humidity environment.

The decomposition foamable compound contained in the foamable composition (4) of the reference invention is selected from monomers that are not polymerized and cured by irradiation with active energy rays.
Therefore, if a coating solution containing the foamable composition (4) of the reference invention and a film-forming resin is coated on a support and then subjected to active energy ray irradiation and heat treatment in sequence, the coating solution layer is dried and solidified. And a foam structure (porous structure) can be formed therein.

Acid generator, base generator The acid generator or base generator used in the foamable composition of the present invention includes a photo-acid generator and a photo-acid generator that are used in chemically amplified photoresists and photocationic polymerization. What is called a base generator can be used.

As a photoacid generator suitable for the present invention,
(1) Diazonium salt compound (2) Ammonium salt compound (3) Iodonium salt compound (4) Sulphonium salt compound (5) Oxonium salt compound (6) Phosphonium salt compound Mention may be made of PF _6- , AsF _6- , SbF ₆ -and CF ₃ SO ₃ -salts of aliphatic onium compounds. As a specific example,
Bisphenylsulfonyldiazomethane,
Biscyclohexylsulfonyldiazomethane,
Bis t-butylsulfonyldiazomethane,
Bis p-methylphenylsulfonyldiazomethane,
Trimethylsulfonium trifluoromethanesulfonate,
Triphenylsulfonium trifluoromethanesulfonate,
Diphenyl-4-methylphenylsulfonium perfluoromethanesulfonate,
Diphenyl-4-tert-butylphenylsulfonium perfluorooctanesulfonate,
Diphenyl-4-methoxyphenylsulfonium perfluorobutanesulfonate,
Diphenyl-4-methylphenylsulfonium tosylate,
Diphenyl-4-methoxyphenylsulfonium tosylate,
Diphenyl-4-isopropylphenylsulfonium tosylate diphenyliodonium trifluoromethanesulfonate,
Diphenyliodonium tosylate,
Diphenyliodonium chloride,
Diphenyliodonium hexafluoroarsenate,
Diphenyliodonium hexafluorophosphate,
Diphenyliodonium nitrate,
Diphenyliodonium perchlorate,
Diphenyliodonium trifluoromethanesulfonate,

Bis (methylphenyl) iodonium trifluoromethanesulfonate,
Bis (methylphenyl) iodonium tetrafluoroborate,
Bis (methylphenyl) iodonium hexafluorophosphate,
Bis (methylphenyl) iodonium hexafluoroantimonate,
Bis (4-tert-butylphenyl) iodonium trifluoromethanesulfonate,
Bis (4-tert-butylphenyl) iodonium hexafluorophosphate,
Bis (4-tert-butylphenyl) iodonium hexafluoroantimonate,
Bis (4-tert-butylphenyl) iodonium perfluorobutanesulfonate,
2-methyl-4,6-bis (trichloromethyl) -1,3,5-triazine,
2,4,6-tri (trichloromethyl) -1,3,5-triazine,
2-phenyl-4,6-ditrichloromethyl-1,3,5-triazine,
2- (p-methoxyphenyl) -4,6-ditrichloromethyl-1,3,5-triazine,
2-naphthyl-4,6-ditrichloromethyl-1,3,5-triazine,
2-biphenyl-4,6-ditrichloromethyl-1,3,5-triazine,
2- (4′-hydroxy-4-biphenyl) -4,6-ditrichloromethyl-1,3,5-triazine,
2- (4′-methyl-4-biphenyl) -4,6-ditrichloromethyl-1,3,5-triazine,
2- (p-methoxyphenylvinyl) -4,6-bis (trichloromethyl) -1,3,5-triazine,
2,6-di-tert-butyl-4-methylpyrylium trifluoromethanesulfonate,
Trimethyloxynium tetrafluoroborate,
Triethyloxynium tetrafluoroborate,
N-hydroxyphthalimide trifluoromethanesulfonate,
N-hydroxynaphthalimide trifluoromethanesulfonate,
Etc.
Of these, iodonium salt compounds and sulfonium salt compounds are preferred.

  In addition to the onium compounds, sulfonates that generate sulfonic acid upon irradiation with active energy rays, such as 2-phenylsulfonylacetophenone, halides that generate hydrogen halide upon irradiation with active energy rays, such as phenyltribromo. Methylsulfone and 1,1-bis (4-chlorophenyl) -2,2,2-trichloroethane, and ferrocenium compounds that generate phosphoric acid upon irradiation with active energy rays, such as bis (cyclopentadienyl) ferrocenium hexa Fluorophosphate, bis (benzyl) ferrocenium hexafluorophosphate, and the like can be used.

  Moreover, in order to expand the wavelength region of the active energy ray of the photoacid generator, a photosensitizer may be used in combination as appropriate. For example, examples of photosensitizers for onium salt compounds include acridine yellow, benzoflavin, and acridine orange.

As a photobase generator suitable for the present invention,
(1) Oxime ester compounds (2) Ammonium compounds (3) Benzoin compounds (4) Dimethoxybenzylurethane compounds (5) Orthonitrobenzylurethane compounds As an amine. In addition, a base generator that generates ammonia or hydroxy ions by the action of light may be used. These include, for example, N- (2-nitropentyloxycarbonyl) piperidine, 1,3-bis [N- (2-nitrobenzyloxycarbonyl) -4-piperidyl] propane, N, N'-bis (2-nitrobenzyl). It can be selected from oxycarbonyl) dihexylamine, O-benzylcarbonyl-N- (1-phenylethylidene) hydroxylamine, and the like. Further, a compound that generates a base by heating may be used in combination with the photobase generator.

Active energy rays Examples of the active energy rays used in the present invention include ionizing radiation such as electron beams, ultraviolet rays, and γ rays. In these, it is preferable to use an electron beam and an ultraviolet-ray.

Electron beam irradiation When electron beam irradiation is used, in order to obtain a sufficient transmission power, an acceleration voltage is 100 to 1000 kV, more preferably, an electron beam accelerator with 100 to 300 kV is used, and a one-pass absorbed dose is 0.5. It is preferable to control to -20 Mrad (1 rad = 0.01 Gy). If the accelerating voltage or the electron beam irradiation dose is lower than the above range, the transmission power of the electron beam will be insufficient, and the inside of the coating liquid layer cannot be sufficiently transmitted. Not only is the efficiency deteriorated, the strength of the resulting cured coating layer may be insufficient, resulting in decomposition of the resin and additives contained therein, and the resulting foam quality may be unsatisfactory. As the electron beam accelerator, for example, any of an electro curtain system, a scanning type, a double scanning type, or the like may be used, but a curtain beam type electron beam accelerator that can obtain a large output at a relatively low cost is used. preferable. In this curtain beam type electron beam accelerator, the acceleration voltage is preferably 100 to 300 kV and the absorbed dose is preferably controlled to 0.5 to 10 Mrad. Furthermore, in order to produce a foam stably and continuously, it is more preferable that the acceleration voltage is 120 to 250 kV and the absorbed dose is controlled to 2 to 9 Mrad.
In addition, when the oxygen concentration in the irradiation atmosphere is high during electron beam irradiation, generation of acid or base and / or hardening of the curable decomposable compound may be hindered. Substitution with an inert gas such as carbon dioxide is preferred. The oxygen concentration in the irradiation atmosphere is preferably 1000 ppm or less, and more preferably 500 ppm or less in order to obtain more stable electron beam energy.

In the case of ultraviolet irradiation, it is preferable to use an ultraviolet lamp provided with a light source having an energy irradiation intensity of 80 W / cm or more. Depending on the type of light source, ultraviolet lamps include, for example, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, metal halide lamps, and the like. A laser can also be used. The amount of ultraviolet irradiation is set according to the extinction coefficient of the acid generator or the base generator, and is generally preferably 1.0 mJ / cm ² or more, and 10 mJ for more stable and continuous production. / Cm ² or more is more preferable. When using ultraviolet rays or ultraviolet laser light, it is preferably used in the range of 10 to 2000 J / m ² (1 to 200 mJ / cm ² ).

Decomposable foamable compound The decomposable foamable compound (hereinafter abbreviated as decomposable compound) used in the foamable composition of the present invention reacts with an acid or a base to produce one or more low-boiling volatile substances (low-boiling volatile substances). Compound) decomposes and desorbs. That is, this decomposable compound must be previously introduced with a degradable functional group capable of generating a low boiling point volatile substance. The low boiling point is the upper limit of the temperature at which gasification occurs during foaming. Usually, it is preferably 100 ° C. or lower and normal temperature or lower. For example, isobutene has a boiling point of -7 ° C. Examples of the decomposable functional group include a tert-butyl group and a tert-butyloxycarbonyl group that react with an acid, and a urethane group and a carbonate group that react with a base. For example, a tert-butyl group is decomposed by an acid to generate an isobutene gas, and a urethane group is decomposed by a base to generate a carbon dioxide gas, and each gas is released from the decomposable compound. As examples of the acid (or base) decomposable compound, monomers, oligomers, polymer compounds (polymers) and the like can be used. For example, the compounds can be classified into the following compound groups.
(1) Non-curable low molecular weight decomposable compound group (2) Curable monomer based degradable compound group (3) Polymeric degradable compound group Examples represented by curable monomer based degradable compounds In the case of an active energy ray-curable compound containing a vinyl group that causes a polymerization reaction when irradiated with active energy rays, it is easy to form uniform fine bubbles, and a foam having excellent strength is obtained. It is possible to obtain. Specific examples of the decomposable compound are shown below.

Non-curing low molecular weight degradable compound group <acid-decomposable compound>
1-tert-butoxy-2-ethoxyethane,
2- (tert-butoxycarbonyloxy) naphthalene,
N- (tert-butoxycarbonyloxy) phthalimide,
2,2-bis [p- (tert-butoxycarbonyloxy) phenyl] propane The low molecular weight non-curable compound is an activity used in the foamable composition (4) and the foam production method (B) of the reference invention. It is used as a decomposable foamable monomer that is not polymerized and cured by energy ray irradiation.

Non-curing low molecular weight degradable compounds <base degradable compounds>
N- (9-fluorenylmethoxycarbonyl) piperidine,
This compound is a decomposable foamable monomer that is not polymerized and cured by irradiation with active energy rays, and can be used in the foamable composition (4) and the foam production method (B) of the reference invention.

Curable monomer group decomposable compound group <acid decomposable compound>
tert-butyl acrylate,
tert-butyl methacrylate,
tert-butoxycarbonylmethyl acrylate,
2- (tert-butoxycarbonyl) ethyl acrylate,
p- (tert-butoxycarbonyl) phenyl acrylate,
p- (tert-butoxycarbonylethyl) phenyl acrylate,
1- (tert-butoxycarbonylmethyl) cyclohexyl acrylate,
4-tert-butoxycarbonyl-8-vinylcarbonyloxy-tricyclo [5.2.1.0 ² , ⁶ ] decane,
2- (tert-butoxycarbonyloxy) ethyl acrylate,
p- (tert-butoxycarbonyloxy) phenyl acrylate,
p- (tert-butoxycarbonyloxy) benzyl acrylate,
2- (tert-butoxycarbonylamino) ethyl acrylate,
6- (tert-butoxycarbonylamino) hexyl acrylate,
p- (tert-butoxycarbonylamino) phenyl acrylate,
p- (tert-butoxycarbonylamino) benzyl acrylate,
p- (tert-butoxycarbonylaminomethyl) benzyl acrylate,
(2-tert-butoxyethyl) acrylate,
(3-tert-butoxypropyl) acrylate,
(1-tert-butyldioxy-1-methyl) ethyl acrylate,
3,3-bis (tert-butyloxycarbonyl) propyl acrylate,
4,4-bis (tert-butyloxycarbonyl) butyl acrylate,
p- (tert-butoxy) styrene,
m- (tert-butoxy) styrene,
p- (tert-butoxycarbonyloxy) styrene,
m- (tert-butoxycarbonyloxy) styrene,
The curable monomer is polymerized by irradiation with active energy rays, and when the polymer comes into contact with an acid, the acid-decomposable group is decomposed to generate a bubble forming gas. This monomer is used in the foamable composition (1) and the foam production method (A) of the present invention.

Curable monomer group decomposable compound group <base decomposable compound>
4-[(1,1-dimethyl-2-cyano) ethoxycarbonyloxy] styrene,
4-[(1,1-dimethyl-2-phenylsulfonyl) ethoxycarbonyloxy] styrene,
4-[(1,1-dimethyl-2-methoxycarbonyl) ethoxycarbonyloxy] styrene,
4- (2-cyanoethoxycarbonyloxy) styrene,
(1,1-dimethyl-2-phenylsulfonyl) ethyl methacrylate,
(1,1-dimethyl-2-cyano) ethyl methacrylate,
The monomer is polymerized by irradiation with active energy rays. When this polymer reacts with a base, the base-decomposable group is decomposed to generate a bubble-forming gas. This monomer is used in the foamable composition (1) and the foam production method (A) of the present invention.

Degradable compound group of polymer system <acid-decomposable compound>
Poly (tert-butyl acrylate),
Poly (tert-butyl methacrylate),
Poly (tert-butoxycarbonylmethyl acrylate),
Poly [2- (tert-butoxycarbonyl) ethyl acrylate],
Poly [p- (tert-butoxycarbonyl) phenyl acrylate],
Poly [p- (tert-butoxycarbonylethyl) phenyl acrylate],
Poly [1- (tert-butoxycarbonylmethyl) cyclohexyl acrylate],
Poly {4-tert-butoxycarbonyl-8-vinylcarbonyloxy-tricyclo [5.2.1.02,6] decane},
Poly [2- (tert-butoxycarbonyloxy) ethyl acrylate],
Poly [p- (tert-butoxycarbonyloxy) phenyl acrylate],
Poly [p- (tert-butoxycarbonyloxy) benzyl acrylate],
Poly [2- (tert-butoxycarbonylamino) ethyl acrylate],
Poly [6- (tert-butoxycarbonylamino) hexyl acrylate],
Poly [p- (tert-butoxycarbonylamino) phenyl acrylate],
Poly [p- (tert-butoxycarbonylamino) benzyl acrylate],
Poly [p- (tert-butoxycarbonylaminomethyl) benzyl acrylate],
Poly (2-tert-butoxyethyl acrylate),
Poly (3-tert-butoxypropyl acrylate),
Poly [(1-tert-butyldioxy-1-methyl) ethyl acrylate],
Poly [3,3-bis (tert-butyloxycarbonyl) propyl acrylate],
Poly [4,4-bis (tert-butyloxycarbonyl) butyl acrylate],
Poly [p- (tert-butoxy) styrene],
Poly [m- (tert-butoxy) styrene],
Poly [p- (tert-butoxycarbonyloxy) styrene],
Poly [m- (tert-butoxycarbonyloxy) styrene],
When the polymer compound comes into contact with an acid, the acid-decomposable group decomposes to form a bubble-forming gas, and is used in the foamable composition (1) and the foam production method (A) of the present invention.

Degradable compound group of polymer system <base decomposable compound>
Poly {p-[(1,1-dimethyl-2-cyano) ethoxycarbonyloxy] styrene},
Poly {p-[(1,1-dimethyl-2-phenylsulfonyl) ethoxycarbonyloxy] styrene},
Poly {p-[(1,1-dimethyl-2-methoxycarbonyl) ethoxycarbonyloxy] styrene},
Poly [p- (2-cyanoethoxycarbonyloxy) styrene],
Poly [(1,1-dimethyl-2-phenylsulfonyl) ethyl methacrylate],
Poly [(1,1-dimethyl-2-cyano) ethyl methacrylate],
And so on.
When the polymer reacts with a base, the base-decomposable group is decomposed to generate a bubble forming gas. This polymer is used in (1) and the foam production method (A).

Polyethers, polyamides, polyesters, polyimides, polyvinyl alcohols, dendrimers and the like into which degradable functional groups have been introduced can also be used as acid-decomposable or base-decomposable polymer compounds.
The decomposable compound group may be used alone, or two or more different types may be used in combination.

The decomposable compound used in the foamable composition (2) of the present invention is a compound obtained by introducing a decomposable foamable functional group into a compound containing at least one or more types of hydrophobic functional groups. The hydrophobic functional group used in the present invention is preferably selected from the group consisting mainly of an aliphatic group, an alicyclic group, an aromatic group, a halogen group, and a nitrile group. The decomposable and foamable functional group is easily introduced into a hydrophilic functional group selected from the group consisting mainly of a carboxylic acid group, a hydroxyl group and an amine group. Therefore, the decomposable compound of the present invention is preferably a composite compound comprising a decomposable unit in which a decomposable and foamable functional group is introduced into the hydrophilic functional group and a hydrophobic unit containing a hydrophobic functional group. In the more preferable composite compound, the decomposable unit and the hydrophobic unit are vinyl polymers. Hydrophobic units include aliphatic (meth) acrylates such as methyl (meth) acrylate and ethyl (meth) acrylate, aromatic vinyl compounds such as styrene, methylstyrene and vinylnaphthalene, (meth) acrylonitrile compounds, vinyl acetate A compound group, a vinyl chloride compound group, etc. are mentioned. As a representative example of the decomposable compound, the decomposable unit is tert-butyl acrylate in which a tert-butyl group which is a decomposable functional group is introduced into acrylic acid having a carboxylic acid group of a hydrophilic functional group, and Examples thereof include vinyl copolymers comprising a combination in which the hydrophobic unit is methyl acrylate having a hydrophobic functional group methyl group. Specific examples of the decomposable compound comprising a combination of degradable unit / hydrophobic unit are shown below.
tert-butyl acrylate / methyl methacrylate copolymer tert-butyl methacrylate / methyl acrylate copolymer tert-butyl methacrylate / methyl methacrylate copolymer tert-butyl acrylate / ethyl acrylate copolymer tert-butyl acrylate / ethyl methacrylate copolymer Compound tert-butyl methacrylate / ethyl acrylate copolymer tert-butyl methacrylate / ethyl methacrylate copolymer tert-butyl acrylate / styrene copolymer tert-butyl acrylate / vinyl chloride copolymer tert-butyl acrylate / acrylonitrile copolymer p -(Tert-Butoxycarbonyloxy) styrene / styrene copolymer In addition, the degradable unit in the decomposable compound Preparative and hydrophobic unit can be used in combination singly or two or more. The form of copolymerization can be performed arbitrarily such as random copolymerization, block copolymerization, and graft copolymerization. Further, the copolymerization ratio of the hydrophobic unit is preferably 5 to 95% by weight based on the total amount of the decomposable compound, and considering the decomposable foamability of the decomposable compound and the environmental preservation of the foamed structure, 20 to 80%. % Is more preferable.
The decomposable compounds may be used alone or in combination of two or more different types.
The decomposable compound is a compound containing at least one or more kinds of hydrophobic functional groups after the decomposable and foamable functional groups are decomposed and released to generate a bubble forming gas. This decomposable compound is used in the foamable composition (2) and the foam production method (A) of the present invention.

  The decomposable compound used in the foamable composition (3) of the present invention is a compound obtained by introducing a decomposable foamable functional group into a low hygroscopic compound. Furthermore, the equilibrium water absorption rate of the low hygroscopic compound should be less than 10% when measured by the JISK7209D method in an environmental atmosphere at a temperature of 30 ° C. and a relative humidity of 60%. Examples of the low hygroscopic compound having a structure in which a decomposable and foamable functional group can be easily introduced include p-hydroxystyrene and m-hydroxystyrene. Accordingly, examples of the decomposable compound include p- (tert-butoxy) styrene, m- (tert-butoxy) styrene, p- (tert-butoxycarbonyloxy) styrene, and m- (tert-butoxycarbonyloxy) styrene. These may be a curable monomer or a polymer in which one or more kinds are mixed.

Further, a decomposable and foamable functional group may be introduced into a composite compound composed of a combination of a highly hygroscopic compound having a water absorption rate of 10% or more and a low hygroscopic compound having a water absorption rate of less than 10%. However, the composite compound must have a water absorption of less than 10% by an appropriate combination. For example, a copolymer (composite compound) of acrylic acid, which is a highly hygroscopic compound, and p-hydroxystyrene, which is a low hygroscopic compound, has a copolymerization ratio of acrylic acid / p-hydroxystyrene = 90/10 to 0 / 100 is preferable. Specific examples of degradable compounds include
tert-butyl acrylate / p- (tert-butoxy) styrene copolymer tert-butyl acrylate / m- (tert-butoxy) styrene copolymer tert-butyl acrylate / p- (tert-butoxycarbonyloxy) styrene copolymer tert-butyl acrylate / m- (tert-butoxycarbonyloxy) styrene copolymer tert-butyl methacrylate / p- (tert-butoxycarbonyloxy) styrene copolymer Further polyester, polyimide, polyvinyl acetate, polyvinyl chloride Further, a decomposable and foamable functional group may be introduced into a low-hygroscopic polymer material selected from the group consisting of polyacrylonitrile, phenol resin, and dendrimer.
The decomposable compounds may be used alone or in combination of two or more different types.
The decomposable compound becomes a low hygroscopic compound after the decomposable and foaming functional group is decomposed and eliminated to generate a bubble forming gas. This decomposable compound is used in the foamable composition (3) and the foam production method (A) of the present invention.

Foamable composition In addition to the acid generator or base generator and the decomposable foamable compound, other active energy ray-curable unsaturated organic compounds may be used in combination in the foamable composition of the present invention. Examples of combination compounds include
(1) Aliphatic, alicyclic, aromatic 1-6 valent alcohols and polyalkylene glycol (meth) acrylates (2) Aliphatic, alicyclic, aromatic 1-6 valent alcohols with alkylene (Meth) acrylates of compounds obtained by adding oxide (3) Poly (meth) acryloylalkyl phosphate esters (4) Reaction products of polybasic acid, polyol and (meth) acrylic acid (5) Reaction product of isocyanate, polyol, (meth) acrylic acid (6) Reaction product of epoxy compound and (meth) acrylic acid (7) Reaction product of epoxy compound, polyol, (meth) acrylic acid (8) Melamine and A reaction product of (meth) acrylic acid can be mentioned.

Among the compounds that can be used in combination, the curable monomer and resin can be expected to improve the physical properties of the coating film such as the strength and heat resistance of the coating film and to control the foaming property. Additives such as fillers can be expected to improve foaming properties and optical properties (particularly in the case of white pigments). Moreover, if a curable monomer is used for the decomposable compound and the combination compound, solvent-free coating can be performed, and a production method with less environmental load can be provided.
As a specific example of a combination compound,
Methyl acrylate, ethyl acrylate, lauryl acrylate, stearyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl acrylate, 2-hydroxy Butyl methacrylate, tetrahydrofurfuryl acrylate, tetrahydrofurfuryl methacrylate, caprolactone-modified tetrahydrofurfuryl acrylate, cyclohexyl acrylate, cyclohexyl methacrylate, dicyclohexyl acrylate, isobornyl acrylate, isobornyl methacrylate, benzyl acrylate, benzyl methacrylate, ethoxydiethylene Glycol acrylate, methoxytriethylene glycol acrylate, methoxypropylene glycol acrylate, phenoxy polyethylene glycol acrylate, phenoxy polypropylene glycol acrylate, ethylene oxide modified phenoxy acrylate, N, N-dimethylaminoethyl acrylate, N, N-dimethylaminoethyl methacrylate, 2-ethylhexyl Carbitol acrylate, ω-carboxypolycaprolactone monoacrylate, phthalic acid monohydroxyethyl acrylate, acrylic acid dimer, 2-hydroxy-3-phenoxypropyl acrylate, acrylic acid-9,10-epoxidized oleyl, ethylene glycol monoacrylate maleate Dicyclopentenyloxyethylene Acrylate, acrylate of caprolactone adduct of 4,4-dimethyl-1,3-dioxolane, acrylate of caprolactone adduct of 3-methyl-5,5-dimethyl-1,3-dioxolane, polybutadiene acrylate, ethylene oxide modified phenoxylated phosphorus Acid acrylate, ethanediol diacrylate, ethanediol dimethacrylate, 1,3-propanediol diacrylate, 1,3-propanediol dimethacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1 , 6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol diacrylate, 1,9-nonanediol dimethacrylate, diethylene glycol diacrylate Polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, polypropylene glycol diacrylate, polypropylene glycol dimethacrylate, neopentyl glycol diacrylate, 2-butyl-2-ethylpropanediol diacrylate, ethylene oxide modified bisphenol A diacrylate, polyethylene oxide modified Bisphenol A diacrylate, polyethylene oxide modified hydrogenated bisphenol A diacrylate, propylene oxide modified bisphenol A diacrylate, polypropylene oxide modified bisphenol A diacrylate, ethylene oxide modified isocyanuric acid diacrylate, pentaerythritol diacrylate monostearate, 1,6- Hexanediol jig Sidyl ether acrylic acid adduct, polyoxyethylene epichlorohydrin modified bisphenol A diacrylate, trimethylolpropane triacrylate, ethylene oxide modified trimethylolpropane triacrylate, polyethylene oxide modified trimethylolpropane triacrylate, propylene oxide modified trimethylolpropane tri Acrylate, polypropylene oxide modified trimethylolpropane triacrylate, pentaerythritol triacrylate, ethylene oxide modified isocyanuric acid triacrylate, ethylene oxide modified glycerol triacrylate, polyethylene oxide modified glycerol triacrylate, propylene oxide modified glycerol triacrylate, polypropylene oxide Glycerol triacrylate, pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, caprolactone modified dipentaerythritol hexaacrylate, polycaprolactone modified dipentaerythritol hexaacrylate However, it is not limited to these.

  Furthermore, as part or all of the combined active energy ray-curable unsaturated organic compound, an active energy ray-curable resin having a molecular weight of about 400 to 5000 having a (meth) acryloyl group at the molecular chain end can be combined. . As such a curable resin, for example, polyurethane poly (meth) acrylate polymers such as polyurethane-modified polyether poly (meth) acrylate and polyurethane-modified polyester poly (meth) acrylate are preferably used.

  The foamable composition of the present invention includes, as necessary, additives such as titanium oxide, magnesium oxide, aluminum oxide, silicon oxide, calcium carbonate, barium sulfate, magnesium carbonate, calcium silicate, aluminum hydroxide, clay, talc, silica and the like. One or more kinds of pigments, metal soaps such as zinc stearate, and various surfactants, antioxidants, ultraviolet absorbers, other dispersants, stabilizers, lubricants, colored dyes, etc. You may not.

In the foam production method (B), as the film-forming resin, polyester resins such as ABS resin, polyethylene terephthalate and polybutylene terephthalate, unsaturated polyester resins, polycarbonate resins, polyolefin resins such as polyethylene and polypropylene, and polyolefin composites Resin, polystyrene resin, polybutadiene resin, acrylic resin, methacrylic resin, fluorine resin, polyimide resin, polyacetal resin, polysulfone resin, vinyl chloride resin, methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, starch, polyvinyl alcohol, polyamide resin, phenol resin, melamine A resin, a urea resin, a urethane resin, an epoxy resin, a silicone resin, or the like is appropriately selected and used.
Moreover, you may add reactive compounds, such as a polyvalent isocyanate compound, an epoxy compound, and an organometallic compound. If necessary, the film-forming resin may be mixed with a foamable composition to form a coating layer in the foam production method (A) of the present invention.

  The foamable composition of the present invention can be prepared using a general kneader. For example, two rolls, three rolls, cowless resolver, homomixer, sand grinder, planetary mixer, ball mill, kneader, high speed mixer, homogenizer, and the like. An ultrasonic disperser or the like can also be used.

Production of Foam A foam production method (A) of the present invention comprises applying a coating liquid containing any of the foamable compositions (1), (2), and (3) of the present invention onto a support. An application layer is formed, active energy rays are irradiated to the application layer, and heat treatment is further performed to form a foam structure in the application layer. Thereby, a foamed resin layer is formed on the support.
In the foam production method (B), a coating liquid containing a foamable composition (4) and a film-forming resin is coated on a support to form a coating layer, and the coating layer is irradiated with active energy rays. Further, a heat treatment is performed to form a foam structure in the coating layer. Thereby, a foamed resin layer is formed on the support.
When the decomposable foamable compound contained in the coating solution is a polymer compound, in the method of the present invention, this decomposable polymer compound reacts with an acid or base generated by irradiation with active energy rays in the heat treatment step. Then, the acid or base-decomposable group is decomposed to generate a bubble forming gas and form bubbles. In the coating solution, when the decomposable polymer compound is dissolved in the solvent, the solvent is removed from the coating solution layer by volatilization before irradiation with the active energy ray to solidify the coating solution layer. As the solvent at this time, for example, alcohols such as ethyl acetate, toluene, methyl ethyl ketone, ethanol, and / or water are preferably used. Moreover, it is preferable that it is 10-50 mass%, and, as for solid content concentration of a solvent containing coating liquid, it is more preferable that it is 20-30 mass%. When the concentration is 20 to 30% by mass, the viscosity of the coating solution is preferably 0.5 to 1 Pa · s (500 to 1000 cPs). When the decomposable foamable compound is a curable monomer compound for active energy ray irradiation, it is polymerized in the active energy ray irradiation step to form a polymer, and in the heating step, it reacts with an acid or base to react with the acid. Alternatively, the base decomposable group is decomposed to generate a bubble forming gas. At this time, the above solvent may be used in combination, if necessary, but generally, the use of a solvent is unnecessary because the curable monomer is a liquid.
Further, when the decomposable foamable compound is a monomer that is not polymerized and cured by irradiation with active energy rays, in the foam production method (B), the coating solution is used as the non-polymerizable curable monomer-containing foamable composition (4). And a film-forming resin and, if necessary, a mixture containing the above-mentioned solvent. After the solvent is removed by volatilization and the film-forming resin is solidified, the coating liquid layer is irradiated with active energy rays to generate an acid. Alternatively, a base is generated, which is further heated to react a non-polymer curable monomer with an acid or a base to generate a bubble forming gas, thereby forming a foamed structure therein.

  Moreover, the method of apply | coating a foaming composition containing coating liquid on a support body can use the casting method, the spin coat method, the direct coating method, etc. In addition, a method used for plastic molding such as a melt extrusion method or an injection method can also be used. The former method is preferable in order to satisfy the demand for foam thinning. Although the thickness of the foamed resin layer is not particularly limited, it can be 50 μm or less, but it is preferably not less than a desired cell diameter. Examples of the support include paper, synthetic paper, plastic resin sheet, metal sheet and the like, and these may be used alone, or more than these steps may be laminated to each other. Examples of the plastic resin sheet include polystyrene resin sheets, polyolefin resin sheets such as polyethylene and polypropylene, and polyester resin sheets such as polyethylene terephthalate. The metals constituting the metal sheet include aluminum and copper. Etc. The foam may be used with the foamed resin layer formed on the support, or the foamed resin layer may be peeled from the support and used as a single foam sheet.

Average cell diameter In order to foam the composition-containing coating layer coated on the support, it is necessary to perform heat treatment after irradiation with active energy rays. The foamed resin layer of the foam obtained by the method of the present invention has fine bubbles, and the average cell diameter can be controlled by the foaming conditions such as the irradiation energy amount of the active energy ray and the heat treatment temperature. Although there is no restriction | limiting in particular regarding an average bubble diameter, In order to obtain the thinned foam, generally it is preferable that it is 0.005-10 micrometers. When the average cell diameter is smaller than 0.005 μm, the function as a foam may be difficult to be exhibited, and when it is larger than 10 μm, the smoothness of the surface of the foam may be insufficient. Furthermore, in order to obtain a foam having improved functions such as strength and heat insulation in a balanced manner, the average cell diameter is more preferably 0.01 to 5 μm.

  The present invention will be described in detail by the following examples, but the present invention is not limited to these examples. Unless otherwise specified, “parts” and “%” in the examples represent “parts by mass” and “mass%”, respectively.

Example 1
Production of Foam Sheet (1) Formation of Coating Layer Bis (4-tert-butylphenyl) iodonium par as an iodonium salt-based acid generator for 100 parts of poly (tert-butyl acrylate) used as a decomposable compound 3 parts of fluorobutane sulfonate (trademark: BBI-109, manufactured by Midori Chemical Co., Ltd.) were mixed and dissolved in ethyl acetate to prepare a solution having a solid content of 25%, which was used as a coating solution. This coating solution was coated on one side of a support made of transparent polyethylene terephthalate (trademark: Lumirror 75-T60, manufactured by Panac) having a thickness of 75 μm using an applicator bar having a coating gap width of 150 μm. Immediately thereafter, the solvent was evaporated and removed by leaving it in a constant temperature dryer at a temperature of 80 ° C. for 10 minutes. A thin, colorless and transparent coating layer was formed on a polyethylene terephthalate support. The thickness of the coating layer was adjusted within the range of 30 μm.

(2) Electron beam irradiation The coating layer formed by the step (1) was irradiated with an electron beam under conditions of an acceleration voltage of 175 kV, an absorbed dose of 8 Mrad, and an oxygen concentration of 500 ppm or less. The obtained coating layer remained colorless and transparent similarly to the coating layer after the step (1).

(3) Foaming by heat treatment The coating layer obtained by the step (2) could be foamed by leaving it in a thermostat kept at a temperature of 100 ° C. for 2 minutes and subjecting it to a heat treatment. At this time, the coating layer changed from colorless and transparent to white, and a foamed resin layer was formed. That is, a thin foamed resin layer having fine bubbles could be formed. The foamed resin layer had a thickness of 35 μm and was peeled from the support to obtain a single foam sheet.

Evaluation in the heating and foaming process (1)
In order to confirm the foam structure of the obtained foamed resin layer, the cross section was observed. That is, the coating resin layer before and after foaming is peeled off from the support, the sample is frozen and cleaved in liquid nitrogen, and a gold vapor deposition process is performed on the cross section of the obtained resin layer. Using an electron microscope (trademark: S-510, manufactured by Hitachi, Ltd.), observation was performed at an enlargement ratio of 10 to 5000 times.
(1) The “thickness of the coated part resin layer” was measured in cross-sectional images before and after heating and foaming (magnification: 2500 times) observed with the electron microscope.

(2) “Presence / absence of foaming” was expressed as “O” when a sponge-like foamed structure was observed in the observed cross-sectional image (magnification: 2500 times), and “X” when it was not.
(3) About “average bubble diameter”, 100 bubbles were randomly selected from the observation image (magnification: 5000 times) of the cross section of the foamed resin layer, and the average of their diameters was calculated.
(4) “Surface smoothness” was visually observed and evaluated. Compared with the state before foaming, the smoothness of the sheet surface was not lost, and there were no irregularities.

Evaluation of environmental preservation (2)
In order to examine the environmental preservation property of the obtained foamed resin layer, the foamed resin layer was allowed to stand for 150 hours in a sealed container maintained at 30 ° C. and 60%, and then the foamed structure was confirmed. The presence or absence of a foam structure is determined in accordance with the evaluation (1). The sponge-like foam structure and the one in which the bubble diameter is maintained are marked as ◎. The sponge-like foam structure is maintained but the bubble diameter is changed (expanded). (Or reduced) was marked with ◯, and those with no spongy foam structure maintained as x. Further, when the film made of the composition of the foamed resin layer was left for 150 hours in an environmental atmosphere at a temperature of 30 ° C. and a relative humidity of 60%, the equilibrium water absorption rate of the film was measured. The equilibrium water absorption was measured according to JIS K7209.

Example 2
In the same manner as in Example 1, a thin-film foam sheet having fine bubbles was produced. However, in the process (2) of Example 1, ultraviolet rays were used instead of the electron beams used as active energy rays. This ultraviolet ray was irradiated using an ultraviolet curing device (manufactured by Eye Graphics) having a 120 w / cm high-pressure mercury lamp so that the irradiation dose was 100 mJ / cm ² . The test results are shown in Table 1.

Example 3
In the same manner as in Example 1, a thin-film foam sheet having fine bubbles was produced. However, instead of the bis (4-tert-butylphenyl) iodonium perfluorobutanesulfonate used as the iodonium salt acid generator in the step (1) of Example 1, diphenyl-4 was used as the sulfonyl salt acid generator. -Methoxyphenylsulfonium perfluorobutanesulfonate (trademark: MDS-109, manufactured by Midori Chemical) was used. The test results are shown in Table 1.

Example 4
In the same manner as in Example 1, a thin-film foam sheet having fine bubbles was produced. However, in the step (1) of Example 1, a tert-butyl acrylate monomer was used instead of the poly (tert-butyl acrylate) used as the decomposable compound. The coating solution used was a solution in which 3 parts of bis (4-tert-butylphenyl) iodonium nonafluorobutanesulfonate was mixed and dissolved as an acid generator with respect to 100 parts of tert-butyl acrylate monomer. The test results are shown in Table 1.

Example 5
In the same manner as in Example 1, a thin-film foam sheet having fine bubbles was produced. However, a copolymer of tert-butyl acrylate (60% by weight) and methyl methacrylate (40% by weight) instead of poly (tert-butyl acrylate) used as the decomposable compound in the step (1) of Example 1 Was used. The test results are shown in Table 1.

Example 6
In the same manner as in Example 1, a thin-film foam sheet having fine bubbles was produced. However, instead of the poly (tert-butyl acrylate) used as the decomposable compound in the step (1) of Example 1, a copolymer of tert-butyl acrylate (80% by weight) and styrene (20% by weight) was used. Using. The test results are shown in Table 1.

Example 7
In the same manner as in Example 1, a thin-film foam sheet having fine bubbles was produced. However, p- (tert-butoxycarbonyloxy) styrene was used in place of the poly (tert-butyl acrylate) used as the decomposable compound in the step (1) of Example 1. The test results are shown in Table 1.

Example 8
In the same manner as in Example 1, a thin-film foam sheet having fine bubbles was produced. However, instead of poly (tert-butyl acrylate) used as the decomposable compound in the step (1) of Example 1, tert-butyl acrylate (20% by weight) and p- (tert-butoxycarbonyloxy) styrene ( 80% by weight) of copolymer was used. The test results are shown in Table 1.

Example 9
In the same manner as in Example 1, a thin-film foam sheet having microbubbles was produced. However, instead of the poly (tert-butyl acrylate) used as the decomposable compound in the step (1) of Example 1, poly {p-[(1,1-dimethyl-2-phenylsulfonyl) ethoxycarbonyloxy] Styrene} was used, and a dimethoxybenzyl urethane base generator was used in place of the iodonium salt acid generator. The test results are shown in Table 1.

Reference example 1
In the same manner as in Example 1, a thin-film foam sheet having fine bubbles was produced. However, in the step (1) of Example 1, 2,2-bis [4- (tert-butoxycarbonyl) was used as the non-curable low molecular weight compound instead of the poly (tert-butyl) acrylate used as the decomposable compound. Oxy) phenyl] propane was used, and 1000 parts of a polyester resin (trade name: Byron 200, manufactured by Toyobo Co., Ltd.) was mixed as a film-forming resin. The solvent for the coating solution was toluene: MEK = 1: 1 instead of ethyl acetate, and the temperature condition for evaporating and removing the solvent was 100 ° C. instead of 80 ° C. The test results are shown in Table 1.

Comparative Example 1
Except that the electron beam irradiation step was not performed in step (2) of Example 1, the other operations were performed in the same manner as in Example 1, but a foam sheet could not be produced. The test results are shown in Table 1.

Comparative Example 2
The same operation as in Example 1 was performed. However, instead of poly (tert-butyl acrylate) used as the decomposable compound in the step (1) of Example 1, polyethylene that is not a decomposable compound was used, and 100 parts of this polyethylene was subjected to an iodonium salt acid. A kneaded mixture of 3 parts of bis (4-tert-butylphenyl) iodonium perfluorobutanesulfonate (trademark: BBI-109, manufactured by Midori Chemical) was used as a coating solution. However, a foam sheet was not obtained. The test results are shown in Table 1.

Comparative Example 3
100 parts of a PET resin was impregnated with 10 parts of carbon dioxide as a foaming agent under a pressure of 5.5 MPa for 10 hours, and extruded into a sheet so as to have a thickness of 35 μm. Then, although it heated at 150 degreeC under normal pressure for 0.5 minute, a foam sheet was not able to be created. The test results are shown in Table 1.

Comparative Example 4
A coating solution is prepared by mixing 3 parts of 4,4′-oxybis (benzenesulfonylhydrazide) as a chemical foaming agent with 100 parts of poly (tert-butyl acrylate) used as a decomposable compound, and this is transparent. It coated on the support body which consists of a polyethylene terephthalate sheet | seat. Then, the foam sheet was able to be produced by heating this at 155 ° C. for 2 minutes. However, a foamed structure having microbubbles was not formed due to excessive swelling of the bubbles.

In Examples 1 to 4 using a combination of an acid generator and an acrylate-based decomposable compound having a tert-butyl group, a heat treatment after irradiation with active energy rays makes it difficult to achieve with the conventional method. A thin foam sheet having air bubbles and a thickness of 50 μm or less could be produced. Also, the appearance such as surface smoothness was good. Example 5 and Example 6 using a decomposable compound in which a decomposable foamable functional group was introduced into a compound having at least one kind of hydrophobic functional group, and a decomposable foamable functional group was introduced into a low hygroscopic compound Also in Example 7 and Example 8 using the decomposable compound, a foam sheet having fine bubbles was obtained. Furthermore, the foamed sheet was excellent in environmental preservation, in which the formed microbubbles did not disappear even when left in a high humidity environment.
In Example 9 using the base generator, the same results as in Examples 5 to 7 were obtained. Moreover, also in Reference Example 1 using a low-molecular decomposition foamable compound having no polymerization curability, a foam sheet having fine bubbles was obtained by using a film-forming resin together with the decomposition foamable compound.
On the other hand, in Comparative Example 1 in which active energy ray irradiation was not performed, in Comparative Example 2 in which polyethylene that is not a degradable compound was used, and in Comparative Example 3 in which an inert gas was impregnated and saturated in a PET resin, a thin sheet was possible. However, the foam sheet could not be obtained because the gas bubbles could not be sufficiently confined in the thin film body. In Comparative Example 4 using a conventional chemical foaming agent, a foam sheet was obtained, but the bubble size was large and the surface smoothness was poor.

Claims (5)

Decomposing and foaming that includes an acid generator that generates an acid by the action of active energy rays or a base generator that generates a base, and further decomposes and desorbs one or more low-boiling volatile substances by reacting with the acid or base. Including a compound having a functional group, wherein the decomposable foamable compound is:
1. 1. a film-forming polymer, and A composition for producing a foam, which is selected from monomers that form a film-forming polymer by polymerization upon irradiation with active energy rays.   The composition for foam production according to claim 1, wherein the decomposable foamable compound is a compound in which the decomposable foamable functional group is introduced into a compound containing at least one or more kinds of hydrophobic functional groups.   The composition for foam production according to claim 1, wherein the decomposable foamable compound is a compound in which the decomposable foamable functional group is introduced into a low hygroscopic compound.   4. The foam according to claim 3, wherein an equilibrium water absorption rate of the low hygroscopic compound is less than 10% when measured by the JISK7209D method in an environmental atmosphere at a temperature of 30 ° C. and a relative humidity of 60%. Composition for manufacture.   A coating solution containing the composition for producing a foam according to any one of claims 1 to 4 is coated on a support to form a coating layer, the coating layer is irradiated with active energy rays, and further subjected to heat treatment. A foam obtained by applying and forming a foam structure in the coating layer.