JP2006124499A - Method for producing unevenly foamed article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an unevenly foamed article, capable of obtaining a zone having a high bubble density while setting the diameter of the bubbles in a fine range, and further, obtaining e.g. a wide pattern of a bubble distribution such as a 3-dimensional bubble distribution, etc., optionally and easily. <P>SOLUTION: This method for producing the unevenly foamed material is provided by performing a molding process of making a foaming composition containing an acid-forming agent forming an acid by the action of radiation energy or a base-forming agent for forming a base, and a decomposition blowing compound having a decomposition blowing functional group of decomposing and releasing ≥1 kind of a low boiling point vaporizable substance by reacting with the acid or base, into a molded article, and then a foaming process of foaming by imparting radiation energy and thermal energy. Any of ≥1 radiation energy and thermal energy imparted to the molded article, the concentration of decomposition-blowing functional group and the concentration of the acid-forming agent or base-forming agent is made as a prescribed uneven distribution. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a non-uniform foam in which the size of the bubble diameter and the density of the bubble density vary depending on the position. More specifically, the present invention relates to a method for producing a non-uniform foam which can obtain a region having a high cell density while keeping the cell diameter in a fine range.

Since the foam has various characteristics, it is used in various industrial fields (Non-patent Documents 1 and 2). Specific foaming characteristics include color development, bulkiness, dryness, swelling, softness, breathability, heat insulation, low dielectric constant, light scattering, light reflectivity, concealment, whiteness, and opacity , Wavelength selective reflection and transmission, light weight, buoyancy, sound insulation, sound absorption, buffering, cushioning, absorptive, adsorptive, storage, permeability, filterability, etc. It is used for packaging materials, building materials, medical materials, electrical equipment materials, electronic information materials, automotive materials, etc.
A uniform foam with a uniform distribution of cell diameter and cell density has the same foaming characteristics regardless of the portion of the foam. On the other hand, in the non-uniform foam in which the distribution of the bubble diameter and the bubble density (hereinafter sometimes collectively referred to as “bubble distribution”) varies depending on the position, the foaming characteristics also vary depending on the bubble distribution. Therefore, it is expected to have advanced functionality that cannot be realized with a uniform foam.
Examples of the non-uniform foam include an inclined foam having a continuous or stepwise (discontinuous) bubble distribution, and a partial foam in which unfoamed areas and foamed areas are alternately arranged. Can be mentioned.

  The non-uniform foam can be obtained by controlling the foaming state so that the size of the cell diameter and the density of the cell density change in position. In the past, attempts have been made to obtain heterogeneous foams having a desired cell distribution using various chemical foaming methods and physical foaming methods.

As a manufacturing method of the heterogeneous foam by a chemical foaming method, the manufacturing method described in patent document 1 and patent document 2 is mentioned, for example. Patent Document 1 discloses a method in which a bright part of an interference fringe is foamed and a dark part is not foamed by irradiating a polymer film impregnated with a photofoaming compound such as a diazo compound with interference light of an argon laser. ing.
In Patent Document 2, the coating layer containing the thermally foamable compound and the photopolymerizable compound is irradiated with ultraviolet rays through a photomask and heated to foam in the non-irradiated part, and the irradiated part has a foaming suppression effect due to polymerization. A method of becoming unfoamed is disclosed.
In these methods, the foaming state is controlled by controlling the exposure intensity.

In recent years, a material called microcellular plastic has been studied as a physical foaming method. Microcellular plastic is a foam having a fine bubble diameter of 0.1 to 10 μm and a high bubble density of 10 ⁹ to 10 ¹⁵ / cm ^3. Yes, proposed by N.P. Suh et al. At Massachusetts Institute of Technology (Patent Document 3).
This foam is obtained by impregnating and saturated an inert gas such as carbon dioxide or nitrogen into a thermoplastic under high pressure or supercritical conditions (about 10 wt%) (gas saturation step), followed by decompression and heating. It is manufactured in combination with a foaming process (foaming process). In this foam production method, the amount of impregnation of the inert gas can be increased, so that a large number of fine bubbles can be formed.
Examples of producing a non-uniform foam by this production method include the production methods disclosed in Patent Document 4 and Patent Document 5. In Patent Document 4, a gradient is given to the impregnation concentration of the inert gas in the gas saturation step. Moreover, in patent document 5, the front and back of the sheet | seat impregnated with gas in the foaming process are heated at different temperatures.

The present inventors include 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 the acid or base to produce one or more kinds of low-boiling volatile substances. A foamable composition comprising a compound having a decomposable foamable functional group that decomposes and desorbs has been proposed. According to this composition, the foam which has a microbubble is obtained (patent document 6).
Toray Research Center, “Foam / Porous Material Technology and Application Development”, 1996 Technical Information Association, “Resin Foaming Technology”, 2001 JP-A-5-72727 Japanese Patent No. 3422384 U.S. Pat. No. 4,473,665 Japanese Patent Laid-Open No. 11-80408 JP 2002-363324 A Japanese Patent Laid-Open No. 2004-002812

  In recent years, the material level has been remarkably advanced, and the required level for the bubble diameter of the foam has been increased from several μm order to nm order. In order to efficiently develop the foaming characteristics, it is important to increase the bubble density. Accordingly, there is a demand for a method for producing a non-uniform foam that can obtain a region having a high cell density while keeping the cell diameter in a fine range. Furthermore, there is also a demand for a method for producing a non-uniform foam that can easily and easily obtain a wide range of bubble distributions, such as a three-dimensional bubble distribution. However, as described below, the above-described conventional chemical foaming method and physical foaming method cannot satisfy these requirements.

First, in the conventional chemical foaming method, it seems that the bubble density can be increased by adding a large amount of a chemical foaming agent. However, the addition of a large amount of the chemical foaming agent increases the plastic effect of the chemical foaming agent and softens the base polymer. As a result, bubbles easily grow and huge bubbles are formed. In addition, the addition of a large amount of chemical foaming agent also causes new adverse effects such as a decrease in the mechanical properties of the base polymer and a decrease in the strength of the foam.
Therefore, in practice, the amount of chemical foaming agent added is limited, and it has been difficult to obtain a region having a high cell density while keeping the cell diameter in a fine range (particularly, the cell diameter is 1 μm or less).
Further, since the control means for the foaming state is substantially limited to the control of the exposure intensity, it is difficult to control the direction of the bubble distribution in the same foam in three dimensions.

Further, in the physical foaming method, a gas outflow phenomenon occurs in which a part of the gas impregnated with high pressure is diffused from the plastic surface before the foaming process. Therefore, it was practically difficult to form bubbles with a bubble diameter of 1 μm or less at high density.
Furthermore, the change direction of the bubble distribution is also limited to the thickness direction from the surface layer to the inside. Therefore, it is difficult to control the direction of the bubble distribution in the same foam in three dimensions.

  Moreover, according to the composition of patent document 6, although it turned out that the production | generation of a microbubble is possible, it was not examined at all about controlling bubble distribution. Therefore, it was not clear whether this composition could provide a heterogeneous foam having a high cell density region while keeping the cell diameter in a fine range.

  In view of the above circumstances, the present invention can obtain a region having a high bubble density while keeping the bubble diameter in a fine range, and can obtain a wide range of bubble distributions arbitrarily and easily, for example, a three-dimensional bubble distribution. It is an object to provide a method for producing a non-uniform foam.

The present invention includes the following aspects: [1] An acid generator that generates an acid by the action of radiation energy or a base generator that generates a base, and one or more low-boiling volatile substances that react with the acid or base Forming step of forming a foamable composition containing a decomposable foamable functional group having a decomposable foamable functional group for decomposing and desorbing the product, and foaming step of applying radiation energy and thermal energy to the molded product to foam (A) Radiation energy applied to the molded body, (b) Thermal energy applied to the molded body, (c) Decomposable foamable functional group concentration in the molded body, (d) In the molded body A method for producing a heterogeneous foam, wherein at least one of the acid generator and the base generator has a predetermined nonuniform distribution.

  [2] The method for producing a non-uniform foam according to [1], wherein the foaming step includes a radiation irradiation step of irradiating the molded body with radiation and a heating step of heating the molded body after the radiation irradiation step. .

[3] As described in [1] or [2], by irradiating the molded body with radiation through a photomask, (a) the radiation energy applied to the molded body has a predetermined non-uniform distribution. A method for producing a non-uniform foam.
[4] The method for producing a non-uniform foam according to [3], wherein the photomask is printed on a base material that transmits radiation with an ink that shields radiation.
[5] The method for producing a non-uniform foam according to [3], wherein the photomask is obtained by providing an opening in a base material that shields radiation.

  [6] By bringing heating bodies having different temperatures into contact with different surfaces of the molded body, (b) the thermal energy applied to the molded body has a predetermined non-uniform distribution. 5] The method for producing a heterogeneous foam according to any one of [5].

  [7] By laminating two or more kinds of foamable compositions having different contents of the decomposable foamable functional groups, (c) the concentration of the decomposable foamable functional groups in the molded article is set to a predetermined non-uniform distribution. The method for producing a heterogeneous foam according to any one of [1] to [6].

[8] By laminating two or more foamable compositions having different contents of the acid generator or the base generator, (d) the concentration of the acid generator or the base generator in the molded body is a predetermined value. The method for producing a non-uniform foam according to any one of [1] to [7], which is non-uniform distribution.
The “radiation” in the present invention is not limited to a particle beam generated by radiation decay, but means a broad sense of radiation that refers to all electromagnetic waves and particle beams.

  According to the method for producing a non-uniform foam of the present invention, a region having a high bubble density can be obtained while keeping the bubble diameter in a fine range. In addition, a wide range of bubble distributions such as a three-dimensional bubble distribution can be obtained arbitrarily and easily. Therefore, according to this invention, the highly functional foam to which the foaming characteristic distribution was provided in the same foam can be obtained easily.

The method for producing a heterogeneous foam of the present invention uses, as a raw material, a foamable composition that forms a foam structure by the action of radiation energy and thermal energy. The production method of the present invention includes a foaming composition molding step and a foaming step in which radiation energy and thermal energy are imparted to the molded body obtained in the molding step to foam.
In the present invention, (a) radiation energy applied to the molded body, (b) thermal energy applied to the molded body, (c) concentration of decomposable foamable functional groups in the molded body, (d) in the molded body Any one or more of the acid generator and the base generator concentration is a predetermined non-uniform distribution, whereby a non-uniform foam having a desired cell distribution is obtained.

<Foaming composition>
The foaming composition used in the present invention is a composition that develops foamability by the action of radiation energy and thermal energy. The foamable composition contains at least the following two components.
One of them is an acid generator that generates an acid by the action of radiation energy or a base generator that generates a base. The other is a decomposable and foamable compound that reacts with the generated acid or base to decompose and desorb one or more low-boiling volatile compounds.

(Acid generator and base generator)
Examples of the acid generator or base generator used in the foamable composition used in the present invention include a chemically amplified photoresist and a photoacid generator or a photobase generator generally used for photocationic polymerization. What is called can be used.

As a photoacid generator suitable for the present invention,
(1) Diazonium salt compounds (2) Ammonium salt compounds (3) Iodonium salt compounds (4) Sulfonium salt compounds (5) Oxonium salt compounds (6) Phosphonium salt compounds Mention may be made of PF ₆ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ and CF ₃ SO ₃ ^— salts of aliphatic onium compounds. Although the specific example is enumerated below, it is not limited to what was illustrated.

Bis (phenylsulfonyl) diazomethane,
Bis (cyclohexylsulfonyl) diazomethane,
Bis (tert-butylsulfonyl) diazomethane,
Bis (p-methylphenylsulfonyl) diazomethane,
Bis (4-chlorophenylsulfonyl) diazomethane,
Bis (p-tolylsulfonyl) diazomethane,
Bis (4-tert-butylphenylsulfonyl) diazomethane,
Bis (2,4-xylylsulfonyl) diazomethane,
Bis (cyclohexylsulfonyl) diazomethane,
Benzoylphenylsulfonyldiazomethane,

Trifluoromethanesulfonate,
Trimethylsulfonium trifluoromethanesulfonate,
Triphenylsulfonium trifluoromethanesulfonate,
Triphenylsulfonium hexafluoroantimonate,
2,4,6-trimethylphenyldiphenylsulfonium trifluoromethanesulfonate, p-tolyldiphenylsulfonium trifluoromethanesulfonate,
4-phenylthiophenyldiphenylsulfonium hexafluorophosphate,
4-phenylthiophenyldiphenylsulfonium hexafluoroantimonate,
1- (2-naphthoylmethyl) thiolanium hexafluoroantimonate,
1- (2-naphthoylmethyl) thiolanium trifluoromethanesulfonate,
4-hydroxy-1-naphthyldimethylsulfonium hexafluoroantimonate,
4-hydroxy-1-naphthyldimethylsulfonium trifluoromethanesulfonate,
(2-oxo-1-cyclohexyl) (cyclohexyl) methylsulfonium trifluoromethanesulfonate,
(2-oxo-1-cyclohexyl) (2-norbornyl) methylsulfonium 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,
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- (4-chlorophenyl) -4,6-bis (trichloromethyl) -1,3,5-triazine,
2- (4-methoxyphenyl) -4,6-bis (trichloromethyl) -1,3,5-triazine,
2- (4-methoxy-1-naphthyl) -4,6-bis (trichloromethyl) -1,3,5-triazine,
2- (benzo [d] [1,3] dioxolan-5-yl) -4,6-bis (trichloromethyl) -1,3,5-triazine,
2- (4-methoxystyryl) -4,6-bis (trichloromethyl) -1,3,5-triazine,
2- (3,4,5-trimethoxystyryl) -4,6-bis (trichloromethyl) -1,3,5-triazine,
2- (3,4-dimethoxystyryl) -4,6-bis (trichloromethyl) -1,3,5-triazine,
2- (2,4-dimethoxystyryl) -4,6-bis (trichloromethyl) -1,3,5-triazine,
2- (2-methoxystyryl) -4,6-bis (trichloromethyl) -1,3,5-triazine,
2- (4-butoxystyryl) -4,6-bis (trichloromethyl) -1,3,5-triazine,
2- (4-pentyloxystyryl) -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,
(Α-benzoylbenzyl) p-toluenesulfonate,
(Β-benzoyl-β-hydroxyphenethyl) p-toluenesulfonate,
1,2,3-benzenetriyltrismethanesulfonate,
(2,6-dinitrobenzyl) p-toluenesulfonate,
(2-nitrobenzyl) p-toluenesulfonate,
(4-nitrobenzyl) p-toluenesulfonate,
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.

Furthermore, the following imide compound derivatives having acid generating ability can also be used.
N- (phenylsulfonyloxy) succinimide,
N- (trifluoromethylsulfonyloxy) succinimide,
N- (10-camphorsulfonyloxy) succinimide,
N- (trifluoromethylsulfonyloxy) phthalimide,
N- (trifluoromethylsulfonyloxy) -5-norbornene-2,3-dicarboximide,
N- (trifluoromethylsulfonyloxy) naphthalimide,
N- (10-camphorsulfonyloxy) naphthalimide.

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 Generates 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.

  In addition, a photosensitizer may be used in combination as appropriate in order to shift or expand the wavelength region of light energy activated by the photoacid generator or photobase generator. For example, examples of photosensitizers for onium salt compounds include acridine yellow, benzoflavin, and acridine orange.

  In order to minimize the amount of addition of the acid generator or base generator and the light energy while generating the necessary acid, an acid proliferator or base proliferator (K. Ichimura et al., Chemistry Letters, 551- 552 (1995), JP-A-8-248561, JP-A-2000-3302700) can be used together with an acid generator or a base generator. The acid proliferator is thermodynamically stable at around room temperature, but decomposes with acid and generates a strong acid by itself to greatly accelerate the acid-catalyzed reaction. By utilizing this reaction, it is possible to improve the generation efficiency of acid or base, and to control the foam generation rate and the foam structure.

(Decomposable foamable compound)
A decomposable foamable compound (hereinafter abbreviated as a decomposable compound) used in the foamable composition used in the present invention reacts with an acid or a base to produce one or more low-boiling volatile substances (low-boiling volatile compounds). Is a compound that decomposes and desorbs.
The low boiling point means having a boiling point at which gasification is possible at the time of foaming, that is, a boiling point lower than the temperature at the time of foaming. The boiling point of the low-boiling volatile substance is usually 100 ° C. or lower, preferably room temperature or lower.
Examples of the low boiling point volatile substance include isobutene (boiling point: −7 ° C.), carbon dioxide (boiling point: −79 ° C.), nitrogen (boiling point: −196 ° C.), and the like.

The decomposable compound must be previously introduced with a degradable functional group capable of generating a low boiling point volatile substance.
Among the decomposable functional groups, those that react with acid include tert-butyloxy group represented by the structural formula of -O-tBu, tert-butyloxycarbonyl group represented by the structural formula of -CO-O-tBu,- Examples thereof include a tert-butyl carbonate group represented by the structural formula of O—CO—O—tBu, a keto acid, and a keto acid ester group. At this time, -tBu represents a -C (CH _{3) 3.}
By reacting with an acid, tert-butyloxy group and tert-butyloxycarbonyl group are isobutene gas, tert-butyl carbonate group is isobutene gas and carbon dioxide, keto acid sites are carbon dioxide, keto acid esters such as tert-keto acid tert -Butyloxy group generates carbon dioxide and isobutene gas.
Examples of those that react with the base include urethane groups and carbonate groups. By reacting with the base, the urethane group and the carbonate group generate carbon dioxide gas.

The form of the decomposable compound may be any of a monomer, an oligomer, and a polymer compound (polymer). Degradable compounds can be classified into the following compound groups.
(1) Non-curable low molecular weight degradable compound group (2) Curable low molecular weight degradable compound group (3) High molecular weight degradable compound group

The non-curable low molecular weight decomposable compound group (1) is a low molecular weight degradable compound group that does not cause a polymerization reaction even when radiation energy is applied. The curable low molecular weight decomposable compound group (2) is a compound group that cures by causing a polymerization reaction upon application of radiation energy, and includes a polymerizable group such as a vinyl group. The polymer-based decomposable compound group (3) is a polymer compound (polymer) that is already a polymer.
The decomposable compound group may be used alone or in combination of two or more different types. When the curable low molecular weight decomposable compound group (2) or the high molecular weight degradable compound group (3) is used, it is easy to form uniform fine bubbles and has a high strength. It is possible and preferable.
Although the specific example of a decomposable compound is enumerated below, it is not limited to what was illustrated.

(1) -a, non-curable low molecular weight decomposable compound group (acid decomposable)
1-tert-butoxy-2-ethoxyethane,
2- (tert-butoxycarbonyloxy) naphthalene,
N- (tert-butoxycarbonyloxy) phthalimide,
2,1-bis [p- (tert-butoxycarbonyloxy) phenyl] propane and the like (1) -b, non-curing low molecular weight decomposable compound group (base decomposability)
N- (9-fluorenylmethoxycarbonyl) piperidine, etc.

(2) -a, a curable low molecular weight degradable compound group (acid decomposable)
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 [5.2.1.02,6] 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,
Acryloyl acetate, methacryloyl acetate tert-butyl acryloyl acetate,
tert-Butylmethacryloyl acetate, etc. N- (tert-butoxycarbonyloxy) maleimide

(2) -b, a curable low molecular weight degradable compound group (base degradability)
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, etc.

(3) -a, polymer-based degradable compound group (acid-decomposable)
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],
Polyacryloyl acetic acid, polymethacryloyl acetic acid,
Poly [tert-butyl acroyl acetate],
Poly [tert-butyl methacryloyl acetate]
N- (tert-butoxycarbonyloxy) maleimide / styrene copolymer, etc.

(3) -b, polymeric degradable compound group (base degradability)
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],

  Organic polymer compounds such as polyethers, polyamides, polyesters, polyimides, polyvinyl alcohols and dendrimers into which degradable functional groups have been introduced can also be used as acid-decomposable or base-decomposable polymer compounds. Furthermore, an acid-decomposable or base-decomposable polymer compound in which a degradable functional group is introduced into an inorganic compound such as silica can also be used. Especially, it is preferable that a decomposable functional group is introduce | transduced into the compound group which has a functional group chosen from the group which consists of a carboxylic acid group or a hydroxyl group, and an amine group.

In order to increase the water resistance of the foam, it is also possible to use a compound in which a decomposition foamable functional group is introduced into a compound containing at least one kind of hydrophobic functional group. The hydrophobic functional group 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.
However, since the decomposable 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, the decomposable compound is decomposed and foamed into a hydrophilic functional group. A composite compound comprising a degradable unit into which a functional group is introduced and a hydrophobic unit containing a hydrophobic functional group is preferred. In particular, a vinyl copolymer compound is preferable.
Hydrophobic units include aliphatic (meth) acrylates such as methyl (meth) acrylate and ethyl (meth) acrylate, aromatic vinyl compounds such as styrene, methylstyrene, vinylnaphthalene, (meth) acrylonitrile compounds, acetic acid A vinyl compound group, a vinyl chloride compound group, etc. are mentioned.

Specific examples of the decomposable compound comprising a composite compound of the decomposable unit and the hydrophobic unit are shown below.
tert-butyl acrylate / methyl acrylate copolymer 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 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) s Len / styrene copolymer

Moreover, the decomposable unit and the hydrophobic unit in the decomposable compound can be used singly or in combination of two or more. The form of copolymerization can take any form such as random copolymerization, block copolymerization, and graft copolymerization. In addition, the copolymerization ratio of the hydrophobic unit is preferably 5 to 95% by mass with respect to the total amount of the decomposable compound. The mass% 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.

  In order to increase the water resistance of the foam, the foamable composition is decomposed into a hygroscopic compound having an equilibrium water absorption of less than 10% as measured by the JISK7209D method in an environmental atmosphere at a temperature of 30 ° C. and a relative humidity of 60%. A compound into which a group is introduced can also be used. 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 preferably has 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 the decomposable compound comprising a combination of a high hygroscopic compound and a low hygroscopic compound are shown below.
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

Furthermore, a decomposable and foamable functional group may be introduced into a low hygroscopic polymer material selected from the group consisting of polyester, polyimide, polyvinyl acetate, polyvinyl chloride, 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.

(Foaming composition)
In the foamable composition used in the present invention, in addition to the acid generator or base generator and the decomposable foamable compound, it may be necessary to mix a general resin that becomes the skeleton of the molded article. That is, when a non-curable low molecular weight decomposable compound group is used, it cannot be molded alone, so it is necessary to use it by mixing with the following commonly used resins. A general resin may be either compatible or incompatible when mixed with a decomposable compound.
General resins include polyester resins such as polyethylene terephthalate and polybutylene terephthalate, unsaturated polyester resins, polycarbonate resins, polyolefin resins such as polyethylene and polypropylene, polyolefin composite resins, polystyrene resins, polybutadiene resins, (meth) acrylic resins, Acryloyl resin, ABS resin, fluororesin, polyimide resin, polyacetal resin, polysulfone resin, vinyl chloride resin, methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, starch, polyvinyl alcohol, polyamide resin, phenol resin, melamine resin, urea resin, urethane resin, It can be appropriately selected from commonly used resins such as epoxy resins and silicone resins. Moreover, a gas barrier resin can also be used for the purpose of allowing a low-boiling volatile substance that decomposes and gasifies from a decomposable compound to be contained in the molded body. The gas barrier resin may be mixed, coated or laminated, and in order to allow the low boiling point volatile substance to be contained in the molded body, it is preferable to coat or laminate the molded body surface.
Among the decomposable foaming compounds, the curable low molecular weight decomposable compound group and the high molecular degradable compound group may be used alone or in combination with the generally used resins.

Whether or not the above general resin is used, other unsaturated organic compounds that are cured by radiation energy can be used in combination. 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 And (meth) acrylic acid reaction products.

Among the compounds that can be used in combination, curable monomers and resins can be expected to improve physical properties such as foam strength and heat resistance, and control foamability. Moreover, if a curable monomer is used for the decomposable compound and the combination compound, solvent-free molding can be performed, and a production method with less environmental load can be provided. For example, such materials are used in JP-A-8-17257 and JP-A-9-102230.
Specific examples of the combination compound include 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-hydroxybutyl methacrylate, tetrahydrofurfuryl acrylate, tetrahydrofurfuryl methacrylate, caprolactone-modified tetrahydrofurfuryl acrylate, cyclohexyl acrylate, cyclohexyl methacrylate, dicyclohexyl acrylate, isobornyl acrylate, isobornyl methacrylate, benzyl acrylate Benzylmeta Acrylate, 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 maleate Glycol monoacrylate, disic Pentenyloxyethylene 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 phosphate acrylate, ethanediol diacrylate, ethanediol dimethacrylate, 1,3-propanediol diacrylate, 1,3-propanediol dimethacrylate, 1,4-butanediol diacrylate, 1,4-butanediol di Methacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol diacrylate, 1,9-nonanediol dimethacrylate, di Ethylene 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 diglycidyl 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 triacrylate, 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 modified glycerol triacrylate, pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, caprolactone modified dipentaerythritol hexaacrylate, polycaprolactone modified Although dipentaerythritol hexaacrylate etc. can be mentioned, it is not restricted 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.

(Other ingredients)
The foamable composition used in the present invention can contain additives other than the acid generator or the base generator and the decomposable compound, if necessary. Additives include inorganic or organic compound fillers, dispersants such as various surfactants, reactive compounds and antioxidants such as polyvalent isocyanate compounds, epoxy compounds and organometallic compounds, silicone oils and processing aids. Contains one or more agents, UV absorbers, optical brighteners, anti-slip agents, antistatic agents, anti-blocking agents, anti-fogging agents, light stabilizers, lubricants, softeners, colored dyes, other stabilizers, etc. May be.
By using additives, improvements in moldability, foamability, optical properties (particularly in the case of white pigments), electrical and magnetic properties (particularly in the case of conductive particles such as carbon) and the like can be expected.

Specific examples of inorganic compound fillers include titanium oxide, magnesium oxide, aluminum oxide, silicon oxide, calcium carbonate, barium sulfate, magnesium carbonate, calcium silicate, aluminum hydroxide, clay, talc, silica and other pigments, stearic acid Metal soap such as zinc, as well as dispersants such as various surfactants, calcium sulfate, magnesium sulfate, kaolin, silicate clay, diatomaceous earth, zinc oxide, silicon oxide, magnesium hydroxide, calcium oxide, magnesium oxide, alumina, mica, Asbestos powder, glass powder, shirasu balloon, zeolite, etc. are achieved. Examples of the organic compound filler include cellulose powders such as wood powder and pulp powder.
Examples of the organic compound filler include cellulose powder such as wood powder and pulp powder, and polymer beads. As the polymer beads, for example, those produced from acrylic resin, styrene resin or cellulose derivative, polyvinyl resin, polyvinyl chloride, polyester, polyurethane and polycarbonate, monomers for crosslinking, and the like can be used.
These fillers may be a mixture of two or more.

  Specific examples of the ultraviolet absorber are selected from salicylic acid-based, benzophenone-based, or benzotriazole-based ultraviolet absorbers. Examples of salicylic acid-based ultraviolet absorbers include phenyl salicylate, pt-butylphenyl salicylate, p-octylphenyl salicylate, and the like. Examples of the benzophenone-based ultraviolet absorber include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone. Examples of the benzotriazole ultraviolet absorber include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-5′-t-butylphenyl) benzotriazole and the like.

Specific examples of the antioxidant include monophenol-based, bisphenol-based, polymer-type phenol-based antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants, and the like.
A typical example of the light stabilizer is a hindered amine compound.

The softening agent can be used for the purpose of improving moldability or processability of the molded body. Specifically, ester compounds, amide compounds, hydrocarbon polymers having side chains, mineral oils, liquid paraffins, Examples thereof include waxes.
The ester compound used as the softening agent is not particularly limited as long as it is a mono- or polyester having a structure composed of an alcohol and a carboxylic acid, and even a compound having a hydroxyl group and a carbonyl group terminal in the molecule is blocked in the form of an ester group. It may be a compound. Specifically, stearyl stearate, sorbitan tristearate, epoxy soybean oil, refined castor oil, hydrogenated castor oil, dehydrated castor oil, epoxy soybean oil, extremely hardened oil, trioctyl trimellitic acid, ethylene glycol dioctanoate, pentaerythritol tetra Examples include octanoate.
The amide compound is not particularly limited as long as it is a mono- or polyamide compound having a structure composed of an amine and a carboxylic acid, and may be a compound in which the amino group and carbonyl group ends are left in the molecule, or a compound blocked in the form of an amide group. Good. Specifically, stearic acid amide, behenic acid amide, hexamethylene bis stearic acid amide, trimethylene bisoctylic acid amide, hexamethylene bishydroxy stearic acid amide, triocta trimellitic acid amide, distearyl urea, butylene bis stearic acid Amides, xylylene bis stearic acid amides, distearyl adipic acid amides, distearyl phthalic acid amides, distearyl octadecadioic acid amides, epsilon caprolactam, and derivatives thereof.

  The hydrocarbon polymer having a side chain is preferably a poly α-olefin and classified into a normal oligomer having a side chain having 4 or more carbon atoms. Specifically, ethylene-propylene copolymer and its maleic acid derivative, isobutylene polymer, butadiene, isoprene oligomer and hydrogenated product thereof, 1-hexene polymer, polystyrene polymer and the like are derived from these. Derivatives thereof, hydroxypolybutadiene and hydrogenated products thereof, and terminal hydroxypolybutadiene hydrogenated products.

  The foamable composition used in 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.

<Molding process>
The molding step of the foamable composition is a step of molding the foamable composition into a molded body having a desired shape. There is no limitation in particular in the shape of a molded object, and it determines suitably by the intended purpose of using a foam. Examples of the general shape include a sheet-like material (including a film shape), a fiber-like material, and a rod-like material. The sheet-like material may be an independent sheet that does not use a support or a sheet layer that is in close contact with the support.
The molding step in the present invention is a step for determining the shape. The molded body at the stage of the molding process may be a fluid instead of a solid. For example, a liquid material poured into a specific mold is also included in the molded body in the present invention.

(Forming method of sheet-like material)
As a method for forming the sheet-like material, a method described in Japanese Patent Application Laid-Open No. 2004-2812 or Japanese Patent Application No. 2003-199521 can be used. In general, melt extrusion molding, injection molding, coating molding, and press molding are preferable. These can be laminated.
Moreover, a batch type or a continuous type may be used. When the foaming composition is a solution, a solvent drying treatment may be added.

  In the case of coating molding, after applying the foamable composition to the support using a coating head, if the foamable composition is a solution diluted with a solvent or the like, the solvent content is removed with a dryer, A sheet layer made of a foamable composition is obtained on the support. At this time, the sheet | seat layer which consists of a foamable composition can also be obtained by peeling a sheet | seat layer from a support body. Coating methods include bar coating, air doctor coating, blade coating, squeeze coating, air knife coating, roll coating, gravure coating, transfer coating, comma coating, smoothing coating, and micro gravure. Examples include coating method, reverse roll coating method, multi-roll coating method, dip coating method, rod coating method, kiss coating method, gate roll coating method, falling curtain coating method, slide coating method, fountain coating method, and slit die coating method. .

  Specific examples of the support include paper, synthetic paper, plastic resin sheet, metal sheet, metal vapor deposition sheet, and the like, and these may be used alone or may be laminated with each other. The plastic resin sheet is, for example, a general-purpose plastic sheet such as a polystyrene resin sheet, a polyolefin resin sheet such as polyethylene or polypropylene, and a polyester resin sheet such as polyethylene terephthalate, or an engineering such as a polyimide resin sheet, an ABS resin sheet, or a polycarbonate resin sheet. A plastic sheet etc. are mentioned, Moreover, aluminum, copper, etc. are mentioned as a metal which comprises a metal sheet. Examples of the metal deposition sheet include an aluminum deposition sheet, a gold deposition sheet, and a silver deposition sheet.

  In the case of extrusion molding, a general extrusion molding method using a screw-like extrusion shaft, a ram extrusion molding method using a piston-like extrusion shaft, and the like can be mentioned. For example, a foamable composition extruded from an extruder can be extruded from a die to obtain a sheet-like material via a roll or the like.

(Notes on molding)
Depending on the composition, the foamable composition may be decomposed by heating at, for example, 150 ° C. or higher. Therefore, care must be taken not to lose the net foaming performance prior to the foaming step.
For example, in extrusion molding, when foaming performance is impaired when heated to the melt viscosity of the resin, a solution casting method in which a foamable composition solution is prepared using a solvent in the same manner as coating molding, and molding is performed at room temperature. You can also take the following method.

<Foaming process>
The foaming step is a step of imparting radiation energy and thermal energy to the molded body to cause foaming. The foaming step includes a radiation irradiation step of irradiating the molded body with radiation and a heating step of heating the molded body, and the heating step is preferably performed after the radiation irradiation step. A stable foam can be formed by sequentially performing the radiation irradiation step and the heating step. This is considered to be because bubble nuclei are generated in the radiation irradiation process and the bubble nuclei grow in the heating process.
In addition, each process may be performed continuously or discontinuously.

(Radiation irradiation process)
The radiation used in the radiation irradiation step is preferably ionizing radiation such as electron beam, ultraviolet ray, visible light, and γ-ray. In these, it is especially preferable to use an electron beam or an ultraviolet-ray.

  When irradiating with an electron beam, in order to obtain a sufficient transmission power, an electron beam accelerator having an acceleration voltage of 30 to 1000 kV, more preferably 30 to 300 kV is used, and the absorbed dose of one pass is controlled to 0.5 to 20 Mrad. It is preferable (1 rad = 0.01 Gy). When the acceleration voltage or the electron beam irradiation amount is lower than the above range, the transmission power of the electron beam becomes insufficient, and the inside of the molded body cannot be sufficiently transmitted. On the other hand, if it is larger than this range, not only the energy efficiency is deteriorated, but also the strength of the obtained molded article becomes insufficient, the resin and additives contained therein are decomposed, and the quality of the obtained foam is low. It can be unsatisfactory.

  As the electron beam accelerator, for example, an electro curtain system, a scanning type, a double scanning type, or the like can be used. When the electron beam is irradiated, if the oxygen concentration in the irradiation atmosphere is high, generation of acid or base and / or curing of the curable decomposable compound may be hindered. For this reason, it is preferable to replace the air in the irradiation atmosphere with an inert gas such as nitrogen, helium or carbon dioxide. 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.

  When irradiating with ultraviolet rays, an ultraviolet lamp generally used in the semiconductor / photoresist field, the ultraviolet curing field, or the like can be used. Typical ultraviolet lamps include, for example, halogen lamps, halogen heater lamps, xenon short arc lamps, xenon flash lamps, ultra high pressure mercury lamps, high pressure mercury lamps, low pressure mercury lamps, medium pressure mercury lamps, deep UV lamps, metal halide lamps. There are noble gas fluorescent lamps, krypton arc lamps, excimer lamps, etc., and in recent years, there are also Y-ray lamps that emit an extremely short wavelength (peak at 214 nm). Some of these lamps are ozone-less types that generate less ozone. These ultraviolet rays may be scattered light or parallel light with high straightness.

In order to accurately control the position of the bubble distribution, it is preferable to use parallel light as the radiation. For the ultraviolet irradiation, various lasers such as ArF excimer laser, KrF excimer laser, YAG laser via a harmonic unit including a nonlinear optical crystal, and ultraviolet light emitting diodes can be used.
The emission wavelength of the ultraviolet lamp, laser, or ultraviolet light emitting diode is not limited as long as it does not interfere with the foaming property of the foamable composition. Preferably, the photoacid generator or the photobase generator is efficient in acid or base efficiency. The emission wavelength that is often generated is good. That is, an emission wavelength that overlaps with the photosensitive wavelength region of the photoacid generator or photobase generator to be used is preferable. Furthermore, a light emission wavelength that overlaps the maximum absorption wavelength or the maximum absorption wavelength in the photosensitive wavelength region of these generators is more preferable because the generation efficiency increases. The energy irradiation intensity of ultraviolet rays is appropriately determined depending on the foamable composition.

When an ultraviolet lamp having a high irradiation intensity typified by various mercury lamps and metal halide lamps is used, productivity can be improved, and the irradiation intensity (lamp output) is preferably 30 W / cm or more. The integrated irradiation light quantity (J / cm ² ) of ultraviolet rays is obtained by adding the irradiation time to the energy irradiation intensity, and is appropriately determined depending on the foam composition and the desired bubble distribution. It may be set according to the extinction coefficient of the acid generator or base generator. For stable and continuous production, a range of 1.0 mJ / cm ^{2 to 20} J / cm ² is preferable.
When using an ultraviolet lamp, the irradiation time can be shortened because the irradiation intensity is high. When using an excimer lamp or excimer laser, the irradiation intensity is weak, but it is close to a single light, so if the emission wavelength is optimized for the photosensitive wavelength of the generator, higher generation efficiency and foamability Is possible. When the amount of irradiation light is increased, heat generation may interfere with foaming properties depending on the ultraviolet lamp. At that time, a cooling treatment such as a cold mirror can be performed.

(Heating process)
Although there is no restriction | limiting in particular in the heater which can be used at a heating process, What can be heated by contact heating, induction heating, resistance heating, dielectric heating (and microwave heating), infrared heating, etc. can be illustrated.
Specific examples include an electric or gas infrared dryer using radiant heat, a roll heater using electromagnetic induction, an oil heater using an oil medium, an electric heater, and a hot air dryer using these hot airs. It is done.
In contact heating in which a heating body is brought into contact with the molded body and heated, a heating body such as a metal block, a metal plate, or a metal roll can be used.
In contact heating, heating may be performed while applying pressure. In this case, a hot press machine used for press molding can be used.

In the case of dielectric heating and infrared heating, since the internal heating method directly heats the inside of the material, it is preferable to perform uniform heating instantaneously compared to an external heating method such as a hot air dryer. In the case of dielectric heating, high-frequency energy having a frequency of 1 MHz to 300 MHz (wavelength 30 m to 1 m) is used. A frequency of 6 MHz to 40 MHz is often used. Among dielectric heating, especially microwave heating uses a microwave with a frequency of 300 MHz to 300 GHz (wavelength is 1 m to 1 mm), but 2450 MHz and 915 MHz (same as a microwave oven) are often used.
In the case of infrared heating, an electromagnetic wave having a wavelength of 0.76 to 1000 μm in the infrared region is used. Although the optimum band of the wavelength selected varies depending on the situation from the heater surface temperature and the infrared absorption spectrum of the material to be heated, it is preferable to use a wavelength band of 1.5 to 25 μm, more preferably 2 to 15 μm. it can.

  Furthermore, a heating method used in a general thermal recording printer can also be used. For example, a thermal head that generates heat when an electric current is passed and laser thermal transfer can be used, and a foam having the same pattern can be obtained by writing heat. When obtaining high definition or high resolution, laser thermal transfer is preferable to thermal heads.

<Non-uniform foam>
The foam obtained by the present invention is a non-uniform foam in which the distribution of the bubble diameter and bubble density (which may be collectively referred to as “bubble distribution” as described above) varies depending on the position.

(Bubble diameter)
In the present invention, “bubble diameter” means “bubble diameter”. Specifically, the bubble diameter obtained by image analysis from the observation image of the foam cross section is obtained by averaging. Note that the average is obtained by sampling a region where 100 or more bubbles are measured from approximately the center of the region in the field of view of the cross-sectional image.
The bubble diameter is preferably 10 μm or less and more preferably 0.005 to 10 μm throughout the entire distribution range. If the bubble diameter is smaller than 0.005 μm, the function due to the foam may be difficult to be exhibited. On the other hand, if it is larger than 10 μm, the surface smoothness of the foam may be insufficient. In particular, a thin foam having a thickness of 100 μm or less often has a poor appearance, and therefore 0.005 to 1 μm is particularly preferable.

(Bubble density)
The bubble density in the present invention is the volume density (density per unit volume including the volume including bubbles; g / cm ³ ) obtained directly by the Archimedes method or the expansion ratio (volume density at the time of unfoaming with respect to the volume density at the time of foaming). Ratio), bubble number density (number of bubbles relative to unfoamed volume; number / cm ³ ), etc., or may be evaluated by unit volume conversion display, or obtained by image analysis from an observation image of the foam cross section. You may evaluate by unit area conversion display, such as the bubble occupied area rate (%) and the bubble surface area density (piece / cm < ² >). In the non-uniform foam obtained in the present invention, since the cell density varies depending on the position in the same foam, from the cross-sectional image rather than the unit volume conversion display in Archimedes method that requires a certain amount of uniform foam for measurement. It is preferable to evaluate by a unit area conversion display that can be measured in a spot manner.
The bubble density is obtained by sampling a region where 100 or more bubbles are measured from about the center of the region in the field of view of the cross-sectional image.
The cell density of the foam of the present invention is not particularly limited, but in order to fully express the function of the foam, the cell number density is preferably in the range of 10 ⁹ / cm ³ or more. When this value is converted into a unit area, for example, if the bubble diameter is 1 μm, the bubble occupation area ratio is preferably 0.8% or more.

Typical forms of the uneven distribution of the bubble diameter and bubble density include partial foaming and inclined foaming.
(Partial foaming)
Partial foaming is (1) a form separated into an unfoamed area and a foamed area, or a form separated into a low foamed area and a high foamed area. Among the partial foams, (2) a form in which unfoamed areas and foamed areas are alternately present, or a form in which low foamed areas and high foamed areas are alternately present is also referred to as alternating foaming.
FIG. 1 shows an alternate foam in which non-foamed regions Ia, Ic, Ie and uniform foamed regions Ib, Id are partially arranged alternately. Further, in FIG. 2, uniform foaming regions IIb and IIf having a small bubble diameter and uniform foaming regions IId having a large bubble size are alternately arranged between the non-foaming regions IIa, IIc, IIe and IIg. The alternate foam produced is shown. 1 and 2, M is a matrix of the molded body, and B is a bubble (the same applies to the following drawings). 1 and 2, the width of each region can be arbitrarily changed.

(Inclined foam)
Inclined foaming includes (3) a form in which the bubble diameter or bubble density continuously changes from one end to the other end (or halfway point) in the foaming region, and (4) foaming. In the region, a form in which the bubble diameter or bubble density changes stepwise from one end to the other end (or halfway point) can be mentioned.
The state that changes step by step is a region of two or more stages with different bubble distributions, for example, a state in which it is divided into a low foaming region and a high foaming region, or a low foaming region, a middle foaming region, and a high foaming region. State that changes, or a state that changes in four or more stages.

FIG. 3 shows an inclined foam in which the bubble diameter continuously changes in one direction. FIG. 4 shows an inclined foam whose bubble density is continuously changing in one direction.
In such a distribution, the area is divided into three equal parts in the direction of continuous change, and the average bubble diameter of the area having the smallest bubble diameter or bubble density is D1, and the average bubble occupation area ratio Is S1, and the average bubble diameter in the region where the bubble diameter or bubble density is intermediate is D2, the average bubble occupation area ratio S2, and the average bubble diameter in the region where the bubble diameter or bubble density is the largest. Is D3 and the bubble occupation area ratio S3, the value of D3 / D1 or S3 / S1 is 1.01 or more, preferably 1.1 or more, more preferably 1.2 or more, and particularly preferably 1.5 or more. It is. The average value is a value obtained by selecting and sampling an area where 100 or more bubbles are measured from approximately the center of the area in the field of view of the cross-sectional image.

FIG. 5 shows an inclined foam in which the bubble diameter changes discontinuously (stepwise) in one direction. FIG. 6 shows an inclined foam in which the bubble density changes discontinuously (stepwise) in one direction.
In such a distribution, the region having the largest bubble diameter or bubble density with respect to the average bubble diameter D1 or the average bubble occupation area ratio S1 of the region (Va, VIa) having the smallest bubble diameter or bubble density. When the average bubble diameter D2 or bubble occupation area ratio S2 of (Vc, VIc) is compared, the value of D2 / D1 or S2 / S1 is 1.1 or more, preferably 1.2 or more, more preferably 1 .5 or more. The average value is a value obtained by selecting and sampling a region where 100 or more bubbles are measured from about the center of the region visually.

(Other foam forms)
As other foam forms, (5) the bubble diameter (D) or the bubble density (N) is a continuous or discontinuous distribution function D = F (x), N = F in at least one direction (x) in the foam. A form having (x) is mentioned.
The foamed form of (5) includes a form in which (1) or (2) and (3) or (4) are mixed, and a form in which (3) and (4) are intermediate or mixed. Or the form which a non-foaming or low foaming area | region and a high foaming area | region coexist at random is included.

In the above example, the direction in which the bubble distribution changes is not limited. For example, in the case of a sheet-like foam, a form in which the bubble distribution changes in at least one of the plane direction or the thickness direction is preferable.
In FIGS. 1 to 6, the number of bubbles and the bubble density have been described as changing independently of each other. However, both of them tend to change normally, and when the number of bubbles increases, the bubble density increases. As the number of bubbles decreases, the bubble density tends to decrease.

<Method to make bubble distribution non-uniform>
Desired cell distribution is (a) radiation energy applied to the molded body, (b) thermal energy applied to the molded body, (c) concentration of decomposable foamable functional groups in the molded body, and (d) the molded body. It is obtained by setting any one or more of the acid generator or base generator concentration in the body to a predetermined non-uniform distribution.

(Non-uniform radiation energy)
A method of setting the radiation energy applied to the molded body to a predetermined nonuniform distribution will be described.
For example, as shown in FIG. 7, when the radiation is irradiated along the thickness direction of the molded body 1, the inclined foam whose bubble distribution decreases along the thickness direction due to the difference in the amount of radiation energy reached due to the penetration depth. Can be obtained.

  Moreover, as shown in FIG. 8, the partial foam can also be created by irradiating only a predetermined part of the molded body 1 with radiation using the photomask 2. When the photomask 2 including the drawing pattern is used, a partial foam having the patterns transferred thereon is obtained. The type of pattern may be appropriately designed depending on the application, such as a delta shape, a stripe shape, or a honeycomb shape. The partial foam can also be obtained by direct drawing by electron beam or ultraviolet irradiation.

  In addition, as shown in FIG. 9, a gradient foam can be produced by irradiating the molded body 1 with gradation pattern radiation using a photomask 2 having energy gradation in a gradation pattern. The gradation pattern may be continuous or stepped (discontinuous).

  It is also possible to change the bubble distribution by changing the irradiation time of radiation. For example, as shown in FIG. 10, when a photomask 2 provided with a triangular opening 3 is slid on the molded body 1 during radiation irradiation, the irradiation time will be longer if the triangular apex side 3a slides. The bottom side 3b is shorter and the irradiation time is longer. It is obvious that the same effect can be obtained by sliding the molded body 1. By generating a distribution in the irradiation time in this way, a distribution of radiation energy can be created as in the case of using a photomask having a gradation pattern. Various distributions can be obtained by changing the shape of the opening 3.

As a material of the photomask 2 used in FIGS. 8 to 9, a chrome mask, a metal mask, a silver salt glass mask, a silver salt film, a screen mask, or the like can be used. A mask in which glass is ion-etched, a mask in which interference fringes of a planar lens having a condensing function are drawn with an electron beam, and the like can be used. When irradiating ultraviolet rays with a wavelength of 300 nm or less, it is preferable to use quartz glass as the base material of the photomask. The inclined foam or partial foam obtained in the present invention may be used as a photomask.
As a material of the photomask 2 used in FIG. 10, it is preferable that the acid generator does not easily transmit the radiation having a wavelength capable of generating acid or the base generator, and the opening can be easily formed. It is preferable that the material can be formed. For example, a paperboard, a metal plate, a resin sheet, a glass plate, etc. are mentioned.

When irradiation is performed using a photomask, methods such as contact irradiation and projection irradiation can be employed. In order to transfer the pattern of the photomask with high accuracy, it is preferable that the irradiated light is uniform parallel light.
Examples of the exposure system for irradiating parallel light include an optical system using an integrator and a parabolic mirror, an optical system using a Fresnel lens, and an optical system using a honeycomb board and a diffusion plate (http: / /www.kuranami.co.jp/toku_guide01.htm).
In order to obtain high uniformity, an optical system using an integrator and a parabolic mirror is generally preferable, and a short arc lamp is preferable as a light source used in this optical system. Examples of the short arc lamp include a metal halide lamp, an ultra-high pressure mercury lamp, a mercury xenon lamp, a sodium lamp, and a Y-ray lamp. After a photomask is brought into close contact with a molded body made of a foamable composition, partial foaming having a line & space pattern with a width of several μm is obtained by irradiating parallel ultraviolet light and foaming by heating. The edge at that time can also be clearly transferred.
Further, a method of irradiating radiation that generates interference fringes is also possible.

(Non-uniform thermal energy)
The distribution of thermal energy is preferably adjusted by the heating temperature.
For example, as shown in FIG. 11, when heating the molded body 1 after applying the radiation energy, if the top heating temperatures T ₁ and lower surface heating temperature T ₂ different inclination foam is obtained . Here, if T ₁ > T ₂ , the number of bubbles and / or the bubble density is larger on the upper surface side than on the lower surface side.
Of course, if a heater capable of changing the heating temperature in the plane direction is used, an inclined foam along the plane direction can be formed.

Moreover, it is also possible to produce the partial foam shown in FIG. 12 and the inclined foam shown in FIG. 13 by changing the thermal energy applied to the molded body 1 using a thermal recording printer.
FIG. 12 shows a partial foam obtained by heating the regions XIIb, XIId, and XIIf with a thermal recording printer.
FIG. 13 shows an inclined foam obtained by heating with a thermal recording printer so that the applied thermal energy increases from the right to the left in the figure.

(Non-uniform foaming composition)
The distribution of the decomposition foamable functional group concentration in the molded body and / or the concentration of the acid generator (or base generator) in the molded body can be adjusted by using a plurality of foamable compositions having different compositions. preferable.
Specific examples include the following.
1) An independent sheet in which sheet-like materials having different mixing ratios of decomposable compounds and / or acid generators (or base generators) are laminated.
2) A sheet layer in which coatings having different mixing ratios of decomposable compounds and / or acid generators (or base generators) are applied and laminated on a support.
3) A sheet layer in which paints having different mixing ratios of decomposable compounds and / or acid generators (or base generators) are applied in parallel on a support.
4) The independent sheet which laminated | stacked the sheet-like material of the foamable composition and the non-foamable composition.
5) A sheet layer in which a foamable composition solution and a non-foamable composition coating are applied and laminated on a support.
6) Sheet layer in which a foamable composition solution and a non-foamable composition coating are applied in parallel on a support.

  According to 1) to 3), as shown in FIG. 14, an inclined foam having a cell distribution corresponding to the concentration of the foaming composition (concentration of the decomposable compound and / or acid generator) can be produced. . Further, according to 4) to 6), as shown in FIG. 15, a partial foam having a cell distribution corresponding to the concentration of the foaming composition (concentration of the decomposable compound and / or acid generator) is prepared. Can do.

(3D bubble distribution)
Each of the above-mentioned methods of non-uniformity of radiation energy, non-uniformity of thermal energy, and non-uniformity of the foamable composition as methods for non-uniform bubble distribution are independent of each other. The bubble distribution can be affected. Therefore, by combining two or more of these methods, the direction of the bubble distribution in the same foam can be controlled in three dimensions.

(Bubble diameter or bubble density)
As described above, both the number of bubbles and the bubble density tend to change. When the number of bubbles increases, the bubble density also increases, and when the number of bubbles decreases, the bubble density also tends to decrease.
However, it is possible to change one of them in a focused manner by adjusting the composition of the foamable composition.
For example, by increasing the glass transition point of the foamable composition, it is possible to mainly change the bubble density while keeping the bubble diameter relatively small. Further, by using a three-dimensional crosslinkable foamable composition, it is possible to mainly change the bubble density while keeping the bubble diameter relatively small.

  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 Iodonium salt based on 100 parts of copolymer of tert-butyl acrylate (60% by weight), methyl methacrylate (30% by weight) and methacrylic acid (10% by weight) which is a decomposable compound As an acid generator, 3 parts of bis (4-tert-butylphenyl) iodonium perfluorobutanesulfonate (trademark: BBI-109, manufactured by Midori Chemical) was mixed and dissolved in ethyl acetate to obtain a solid content of 25%. Was prepared and used as a coating solution.
This coating solution was 75 μm thick transparent polyethylene terephthalate, which was dissolved in ethyl acetate to prepare a solution with a solid content of 25%, and this was used as the 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 300 μm. Immediately thereafter, the solvent was evaporated and removed by leaving it in a constant temperature dryer at a temperature of 110 ° C. for 5 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 40 to 50 μm.

(2) Ultraviolet irradiation A line and space pattern chromium mask (made of quartz glass) was brought into close contact with the coating layer formed in the step (1), and ultraviolet irradiation was performed from the photomask side. As the line and space pattern, a pattern in which lines that transmit ultraviolet rays (width: 100 μm) and lines that do not completely transmit ultraviolet rays (gap: width: 100 μm) are alternately arranged. Ultraviolet rays were irradiated using a metal halide lamp as a light source so that the irradiation dose was 2000 mJ / cm ² . After the irradiation, the coating layer obtained by removing the chromium mask remained the same as the coating layer after step (1) and remained colorless and transparent.

(3) Foaming by heat treatment The coating layer obtained in the step (2) was peeled off from the support, and the single film was heat-treated for 5 minutes in a thermostatic chamber maintained at a temperature of 110 ° C. When the film after heating was observed with a microscope (trademark: KH-2700, manufactured by HiRox), as shown in FIG. 16, the ultraviolet irradiation part 10 foamed white in a line shape having a line width of 100 μm, and the non-irradiation part 20 It was confirmed that the colorless and transparent unfoamed portion remained.

(4) Evaluation of foam structure The foam structure in the ultraviolet irradiation part 10 of the film obtained by the said process (3) was confirmed by scanning electron microscope (trademark: S-510, Hitachi make) observation. Cross-sectional observation was performed with a scanning electron microscope (trade name: S-510, manufactured by Hitachi, Ltd.) after the metal film was vapor-deposited on the cross-section obtained by immersing the film in liquid nitrogen. This is shown in FIG.
The foam structure was evaluated based on the bubble diameter and bubble density calculated from the observed image. Specifically, after randomly selecting a section containing a total of about 150 bubble groups from the observation image (magnification magnification 5000 times), and binarizing the bubble groups and the other matrixes The bubble diameter and bubble density were evaluated using an image analyzer (trademark: Image Analyzer V10, manufactured by TOYOBO). At this time, the average value (μm) of the bubble diameter was determined as the bubble diameter, and the bubble occupation area ratio (%) was determined as the bubble density.
As a result, the ultraviolet irradiation part 10 foamed white in a line shape having a line width of 100 μm had a bubble diameter of 0.25 μm and a bubble occupation area ratio of 28%. On the other hand, no bubbles were observed in the colorless and transparent non-irradiated portion 20. In this way, a partial foam having a foam region having a bubble diameter of 1 μm or less could be obtained.

<Example 2>
In the same manner as in Example 1, a foam having a cell distribution was produced. However, in the step (2) of Example 1, a chrome mask having a dot pattern with a diameter of 3 μm is used instead of the line & space pattern, and the uniform ultraviolet light extracted from the Y-ray lamp (peak wavelength 214 nm) is used as the ultraviolet ray. The irradiation dose was 1 J / cm ² .
In the obtained foam, as shown in FIG. 18, the ultraviolet irradiation part 10 having a diameter of 3 μm was foamed white in a dot shape. The foamed structure was the same as in Example 1. On the other hand, the unirradiated part 20 was colorless and transparent, and no bubbles were observed. Thus, by using parallel light, it was possible to obtain partial foaming in which a part of several μm level was foamed.

<Example 3>
In the same manner as in Example 1, a foam having a cell distribution was produced. However, in the step (2) of Example 1, a photomask having a continuous gradation pattern was used instead of the line & space pattern. As shown in FIG. 19, the obtained foam was foamed so as to gradually become white along the mask having a higher transmittance. As shown in FIG. 20, when the foamed structure is evaluated to be representative five points (a to e) while changing to white, the bubble diameter and the bubble occupation density gradually increase in the same film. I was able to confirm. Specifically, each foam structure from point a to point e is (a) a bubble diameter of 0.17 μm, a bubble occupation area ratio of 4%, (b) a bubble diameter of 0.22 μm, and a bubble occupation area ratio of 9% (c). The bubble diameter was 0.29 μm, the bubble occupation area was 16% (d), the bubble diameter was 0.34 μm, the bubble occupation area was 22%, and the bubble diameter was 0.42 μm, and the bubble occupation area was 32% (see FIG. 21). ). In this way, it was possible to obtain an inclined foam having a continuous gradient of cell distribution.

<Example 4>
In step (1) of Example 1, lamination coating was performed so that the thickness of the coating layer was 400 μm. The laminated sheet was irradiated with ultraviolet rays so as to be 1000 mJ / cm ² . As the ultraviolet lamp, a metal halide lamp having an output of 120 w / cm was used. The laminated sheet after irradiation was passed between two metal rolls having different temperatures to be heat-treated and foamed. At this time, the temperature of one metal roll was adjusted to 100 ° C., and the other metal roll was adjusted to 130 ° C.
As a result, from the surface of the laminated sheet in contact with the roll having a high temperature toward the other surface (the surface of the laminated sheet in contact with the roll having a low temperature), the bubble diameter is 0.1 to 1 μm, and the bubble occupation area ratio is 4 to 4%. An inclined foam with a gradient of 30% could be obtained.

<Example 5>
Using three kinds of decomposable compounds in which the copolymerization ratio of tert-butyl acrylate and methyl methacrylate is tert-butyl acrylate / methyl methacrylate = 80/20, 60/40, 40/60, the layers are laminated in the above order. A sheet was prepared by coating. At this time, 3 parts of BBI-109 is mixed with 100 parts of the decomposable compound in each layer. The thickness of each layer was adjusted to 50 μm. The laminated sheet was irradiated with ultraviolet rays so as to be 1000 mJ / cm ² . As the ultraviolet lamp, a metal halide lamp having an output of 120 w / cm was used. After irradiation, foaming was performed by heating at 110 ° C. for 2 minutes.
As a result, it is possible to obtain an inclined foam in which the bubble distribution gradually changes in the thickness direction in which the bubble diameter and the bubble occupation area ratio are increased from the layer having a low tert-butyl acrylate copolymer ratio to the layer having a large amount. I was able to.

  According to the present invention, it is possible to easily provide a foam in which the bubble distribution which cannot be obtained by the conventional method is arbitrarily changed. In addition, it is possible to provide high-functional foams that have foaming characteristics due to the distribution of bubbles, and are widely used in various fields such as packaging materials, building materials, medical materials, electrical equipment materials, electronic information materials, and automotive materials. Give a contribution.

It is a figure which shows alternate foaming typically, (a) is a perspective view, (b) is a graph which shows the relationship between the left-right position in the cross section of (a), and a bubble diameter. It is a figure which shows alternate foaming typically, (a) is a perspective view, (b) is a graph which shows the relationship between the left-right position in the cross section of (a), and a bubble diameter. It is a figure which shows continuous inclined foaming typically, (a) is a perspective view, (b) is a graph which shows the relationship between the left-right position in the cross section of (a), and a bubble diameter. It is a figure which shows continuous inclined foaming typically, (a) is a perspective view, (b) is a graph which shows the relationship between the left-right position in the cross section of (a), and bubble density. It is a figure which shows stepwise gradient foaming typically, (a) is a perspective view, (b) is a graph which shows the relationship between the left-right position in the cross section of (a), and a bubble diameter. It is a figure which shows stepwise gradient foaming typically, (a) is a perspective view, (b) is a graph which shows the relationship between the left-right position in the cross section of (a), and bubble density. It is explanatory drawing of the preparation method of the inclination foam using the difference in the arrival amount of the radiation energy by the penetration depth. It is explanatory drawing of the preparation method of the partial foam using a photomask. It is explanatory drawing of the preparation method of the inclination foam using a photomask. It is explanatory drawing of the preparation method of the inclined foam using irradiation time adjustment by the slide of a photomask. It is a schematic diagram of the inclined foam using the heating temperature difference of front and back. It is a schematic diagram of the partial foam using the printer for thermal recording. It is a schematic diagram of the inclined foam using the printer for thermal recording. It is a schematic diagram of the inclined foam using the several foamable composition from which a composition differs. It is a schematic diagram of the partial foam using the several foamable composition from which a composition differs. 2 is a photograph of the foam obtained in Example 1. It is a photograph which shows the foam structure in the ultraviolet irradiation part of the foam obtained in Example 1. FIG. 2 is a photograph of the foam obtained in Example 2. 4 is a photograph of the foam obtained in Example 3. It is a photograph which shows the foam structure in the ae point of the foam obtained in Example 3. FIG. It is a graph which shows the bubble diameter and bubble occupation area ratio in the ae point of the foam obtained in Example 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Molded object, 2 ... Photomask, 3 ... Opening part,
M ... Matrix, B ... Bubble

Claims (8)

It has an acid generator that generates an acid by the action of radiation energy or a base generator that generates a base, and a decomposition foaming functional group that reacts with the acid or base to decompose and desorb one or more low-boiling volatile substances. A molding step using a foamable composition containing a decomposable foamable compound as a molded body;
A foaming step of foaming by applying radiation energy and thermal energy to the molded body,
(A) Radiation energy applied to the molded body, (b) Thermal energy applied to the molded body, (c) Decomposable foamable functional group concentration in the molded body, (d) Acid generator in the molded body Alternatively, any one or more of the concentrations of the base generator have a predetermined non-uniform distribution.   The method for producing a non-uniform foam according to claim 1, wherein the foaming step includes a radiation irradiation step of irradiating the molded body with radiation and a heating step of heating the molded body after the radiation irradiation step.   3. The non-uniformity according to claim 1, wherein the molded body is irradiated with radiation through a photomask so that (a) the radiation energy applied to the molded body has a predetermined non-uniform distribution. A method for producing a foam.   The method for producing a non-uniform foam according to claim 3, wherein the photomask is obtained by printing on a base material that transmits radiation with an ink that shields radiation.   The method for producing a non-uniform foam according to claim 3, wherein the photomask is provided with an opening in a base material that shields radiation.   The heating energy applied to the molded body is made to have a predetermined non-uniform distribution by bringing heating bodies having different temperatures into contact with different surfaces of the molded body, respectively. The manufacturing method of the heterogeneous foam in any one. By laminating two or more kinds of foamable compositions having different contents of the decomposable foamable functional groups, (c) the concentration of the decomposable foamable functional groups in the molded body has a predetermined non-uniform distribution. The manufacturing method of the heterogeneous foam in any one of Claims 1-6. By laminating two or more foamable compositions having different contents of acid generator or base generator, (d) the concentration of the acid generator or base generator in the molded body is a predetermined non-uniform distribution. The method for producing a heterogeneous foam according to any one of claims 1 to 7.

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