JP2015129290A - Thermally expandable microsphere and use of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide thermally expandable microspheres which have high heat resistance, and whose expansion start temperature is lowered when having been subjected to heat treatment at a temperature lower than the expansion start temperature; and a use of the same.SOLUTION: There are provided thermally expandable microspheres which have an outer shell formed of a thermoplastic resin, and a foaming agent that is included in the outer shell and is vaporized by heating. The thermoplastic resin is formed of a copolymer obtained by polymerizing a polymerizable component containing a carboxyl group-containing monomer. The foaming agent is thermally expandable microspheres containing hydrocarbon B having 13 or more carbon atoms.

Description

  The present invention relates to thermally expandable microspheres and uses thereof.

Thermally expandable microspheres having a structure in which a thermoplastic resin is used as an outer shell and a foaming agent is enclosed in the outer shell are generally referred to as thermally expandable microcapsules. As raw material monomers for thermoplastic resins, vinylidene chloride, (meth) acrylonitrile monomers, (meth) acrylic acid ester monomers and the like are usually used. Moreover, hydrocarbons, such as isobutane and isopentane, are mainly used as a foaming agent (refer patent document 1).
Thermally expandable microcapsules have been used as foaming agents in place of organic foaming agents in recent years when molding resin compositions to obtain lightweight molded products, and to form closed cells inside molded products. Is indispensable. As a thermally expandable microcapsule, a very general microcapsule described in Patent Document 1 starts to expand at a relatively low temperature (about 100 to 140 ° C.). In some cases, expansion may occur during the production of a master batch of thermally expandable microcapsules. In order to prevent such premature expansion before molding of molded products, the processing temperature during preparation of the masterbatch is lowered, or the resin used as the base material to be blended in the masterbatch has a low softening temperature There was a need to choose. In particular, in the latter case, when a heat-resistant resin with a high softening temperature is used as the type of resin used for molding, the heat resistance of the resulting molded product is reduced due to the difference between the resin used for the masterbatch and the type of resin used for molding. There is a problem of doing.

If the expansion start temperature of the thermally expandable microcapsule is increased, the early expansion can be prevented. As such a heat-expandable microcapsule having a high expansion start temperature and high heat resistance, a carboxylic acid-based heat-expandable microcapsule in which the above-mentioned raw material monomer is essentially a carboxylic acid-based monomer is known (see Patent Document 2). . When heat treatment is performed on the carboxylic acid-based thermally expandable microcapsule at a temperature lower than the expansion start temperature, the expansion start temperature after the heat treatment is slightly lower than the expansion start temperature before the heat treatment (see Patent Document 3). .
If the master batch contains carboxylic acid-based thermally expandable microcapsules, premature expansion during preparation of the master batch can be prevented. However, when molding using this masterbatch, the expansion start temperature of the carboxylic acid-based thermally expandable microcapsules is still high, so this masterbatch can be used to mold at a high molding temperature that is higher than the expansion start temperature. Necessary. Here, the high molding temperature is also disadvantageous in terms of energy, and similarly to the previous case, the resin used for the masterbatch and the type of resin used for molding are different. is there. For this reason, the carboxylic acid-based thermal expansion has a physical property that the expansion start temperature is high when a masterbatch is prepared under a temperature lower than the expansion start temperature, but the expansion start temperature is low when the molded product is subsequently formed. Development of functional microcapsules is desired.

US Pat. No. 3,615,972 International Publication No. 03/099955 Pamphlet International Publication No. 2007/072769 Pamphlet

  An object of the present invention is to provide thermally expandable microspheres having high heat resistance and having a low expansion start temperature when heat treatment is performed at a temperature lower than the expansion start temperature, and uses thereof.

As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be achieved with carboxylic acid-based thermally expandable microspheres containing a specific foaming agent, and have reached the present invention.
That is, the thermally expandable microsphere according to the present invention is a thermally expandable microsphere composed of an outer shell made of a thermoplastic resin and a foaming agent encapsulated therein and vaporized by heating. A thermally expandable microsphere composed of a copolymer obtained by polymerizing a polymerizable component containing a carboxyl group-containing monomer.

  Here, the blowing agent includes hydrocarbon A having 12 carbon atoms and hydrocarbon B having 13 or more carbon atoms.

It is preferable that at least one of the following (1) to (4) is satisfied.
(1) The weight ratio of the hydrocarbon B is 90% by weight or less of the foaming agent.
(2) The expansion start temperature of the thermally expandable microspheres is Ts1 (° C.), and the expansion start temperature after the heat treatment of the thermally expandable microspheres for 5 minutes at T (° C.) satisfying the following formula (A): When Ts2 (° C.) is set, the rate of decrease in expansion start temperature (ΔTs) defined by the following calculation formula (B) is more than 3%.
170 ≦ T <Ts1 (A)
ΔTs = [(Ts1−Ts2) / Ts1] × 100 (%) (B)
(3) The expansion start temperature is 180 ° C. or higher.
(4) The polymerizable component further contains a nitrile monomer.

The hollow fine particles according to the present invention can be obtained by heating and expanding the thermally expandable microspheres.
The composition of the present invention comprises at least one granular material selected from the above-mentioned thermally expandable microspheres and hollow fine particles, and a base material component.
The molded product of the present invention is formed by molding the above composition.

  The heat-expandable microspheres of the present invention have high heat resistance and physical properties that lower the expansion start temperature when heat treatment is performed at a temperature lower than the expansion start temperature.

Since the hollow fine particles of the present invention are obtained using the above-mentioned thermally expandable microspheres as raw materials, they have excellent heat resistance.
Since the composition of the present invention contains the thermally expandable microspheres and / or hollow fine particles, it has excellent heat resistance.
Since the molded product of the present invention is obtained by molding the above composition, it is lightweight and has excellent heat resistance.

It is the schematic which shows an example of a thermally expansible microsphere. It is a figure which shows the outline of the softening point determination method of a thermoplastic resin.

[Thermal expandable microspheres]
As shown in FIG. 1, the thermally expandable microsphere of the present invention is a thermally expandable microsphere composed of an outer shell 1 made of a thermoplastic resin and a foaming agent 2 encapsulated therein and vaporized by heating. It is. The thermoplastic resin is a copolymer obtained by polymerizing a polymerizable component including a monomer component containing a carboxyl group-containing monomer as an essential component (that is, a polymerizable component including a carboxyl group-containing monomer). Composed of coalescence.
The average particle size of the thermally expandable microsphere is not particularly limited, but is preferably 1 to 100 μm, more preferably 2 to 80 μm, still more preferably 3 to 60 μm, and particularly preferably 5 to 50 μm.

  The coefficient of variation CV of the particle size distribution of the heat-expandable microspheres is not particularly limited, but is preferably 35% or less, more preferably 30% or less, and particularly preferably 25% or less. The variation coefficient CV is calculated by the following calculation formulas (1) and (2).

(Wherein, s is the standard deviation of the particle size, <x> is an average particle size, x _i is the i-th particle diameter, n is the number of particles.)
The expansion start temperature (Ts1) of the thermally expandable microsphere is not particularly limited, but is preferably 180 ° C. or higher, more preferably 200 ° C. or higher, further preferably 220 ° C. or higher, particularly preferably 230 ° C. or higher, and most preferably 240. It is above ℃. On the other hand, the upper limit of the expansion start temperature is preferably 290 ° C. When the expansion start temperature is less than 180 ° C., the heat resistance is low and sufficient expansion performance may not be obtained. If the expansion start temperature exceeds 290 ° C., a sufficient expansion ratio may not be obtained.

In the thermally expandable microsphere, the expansion start temperature is Ts1 (° C.), and the expansion start temperature after the heat treatment of the thermally expandable microsphere for 5 minutes at T (° C.) satisfying the following formula (A) is Ts2 (° C.). ), The rate of decrease in expansion start temperature (ΔTs) defined by the following formula (B) is preferably more than 3%, more preferably more than 5%, more preferably more than 7%, particularly preferably 9 %, Most preferably more than 10%. The upper limit value of ΔTs is preferably 50%.
170 ≦ T <Ts1 (A)
ΔTs = [(Ts1−Ts2) / Ts1] × 100 (%) (B)

When preparing the masterbatch, if not performed at a temperature lower than the expansion start temperature, the thermally expandable microspheres will expand. For this reason, it is desirable that the thermally expandable microspheres have a high expansion start temperature. Usually, the masterbatch is prepared at a temperature 30 ° C. lower than the expansion start temperature so that the thermally expandable microspheres do not expand. There are many. On the other hand, since molding is often performed at a temperature around the maximum expansion temperature, the difference between the temperature at which the masterbatch is prepared and the temperature at which the molded product is molded is very large and is used when molding the molded product. The resin is often different in type from the resin used in preparing the masterbatch, and the compatibility between the resins is reduced. For this reason, the resulting molded product is greatly reduced in heat resistance by the resin.
In the case of thermally expandable microspheres, which are difficult to lower the expansion start temperature by heating at the time of preparing the master batch, as described in Patent Document 3, it is sufficient to mold the molded product at the temperature at the time of preparing the master batch. The expansion ratio cannot be obtained.

On the other hand, in the thermally expandable microsphere having ΔTs exceeding 3% as described above, the expansion start temperature decreases after the preparation of the masterbatch. Therefore, when the molded product is molded at the temperature at the time of preparing the master batch, a sufficient expansion ratio can be obtained. Furthermore, since the temperature at the time of masterbatch preparation and molding is the same, it becomes possible to make the resin used at the time of masterbatch preparation and the resin used at the time of molding the molded product the same, The obtained molded product has the advantage that there is no decrease in heat resistance due to the resin.
The maximum expansion temperature (Tmax1) of the thermally expandable microsphere is not particularly limited, but is preferably 230 ° C. or higher, more preferably 240 ° C. or higher, further preferably 250 ° C. or higher, particularly preferably 260 ° C. or higher, and most preferably 270. It is above ℃. On the other hand, the upper limit of the maximum expansion temperature is preferably 350 ° C. When the maximum expansion temperature is less than 230 ° C., the heat resistance is low and sufficient expansion performance may not be obtained. If the maximum expansion temperature is higher than 350 ° C., the degree of cross-linking of the outer shell of the thermally expandable microsphere is high, so that a sufficient expansion ratio may not be obtained.

In the thermally expandable microsphere, the maximum expansion temperature is Tmax1 (° C.), and the maximum expansion temperature after heat treatment of the thermally expandable microsphere for 5 minutes at T (° C.) satisfying the above formula (A) is Tmax2 (° C.). ), The reduction rate (ΔTmax) of the maximum expansion temperature defined by the following formula (C) is preferably 20% or less, more preferably 15% or less, particularly preferably 10% or less, and most preferably 7 % Or less. The lower limit value of ΔTmax is preferably 0%. If the reduction rate of the maximum expansion temperature is more than 20%, a sufficient expansion ratio may not be obtained due to a significant decrease in heat resistance.
ΔTmax = [(Tmax1-Tmax2) / Tmax1] × 100 (%) (C)

The maximum expansion ratio of the thermally expandable microsphere is not particularly limited, but is preferably 30 times or more, more preferably 45 times or more, still more preferably 56 times or more, particularly preferably 59 times or more, and further preferably 62 times or more. , Most preferably 65 times or more, and most preferably 80 times or more. On the other hand, the upper limit of the maximum expansion ratio is preferably 200 times. If the maximum expansion ratio is less than 30 times, a sufficient expansion ratio may not be obtained when thermally expandable microspheres are contained in the molded article or the like.
The foaming agent constituting the thermally expandable microsphere is not particularly limited as long as it is a substance that is vaporized by heating. The foaming agent is essentially a hydrocarbon having 13 or more carbon atoms (hereinafter sometimes referred to as hydrocarbon B).

The carbon number of the hydrocarbon B is preferably 14 or more, more preferably 16 or more. Further, the upper limit value of the carbon number of the hydrocarbon B is preferably 25. The hydrocarbon B may be linear, branched or alicyclic, and is preferably aliphatic. Examples of the hydrocarbon B include linear hydrocarbons such as tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nanodecane, eicosan, heneicosan, docosan, tricosan, tetracosan, pentacosan, etc .; isotetradecane, isopentadecane, isohexadecane, 2, 2,4,4,6,8,8-heptamethylnonane, isoheptadecane, isooctadecane, isonanodecane, 2,6,10,14-tetramethylpentadecane, isoeicosane, 2,2,4,4,6,6,8 , 8,10-nonamethylundecane, isophenecosan, isodocosane, isotricosane, isotetracosane, isopentacosane, etc .; branched hydrocarbons such as n-octylcyclohexane, cyclopentadecane, nonylcyclohexane, decylsi Rohekisan, pentadecyl cyclohexane, hexadecyl cyclohexane, heptadecyl cyclohexane, the alicyclic hydrocarbons such as octadecyl cyclohexane. These hydrocarbons B may be used alone or in combination of two or more.
As a foaming agent, the foaming agent 1 and the foaming agent 2 which are shown below can be mentioned as a preferable thing, for example.

Foaming agent 1: Hydrocarbon B containing substantially no boiling point below the softening point of the thermoplastic resin constituting the outer shell Foaming agent 2: C12 hydrocarbon (hereinafter referred to as hydrocarbon A) And hydrocarbon B

The foaming agent 1 contains hydrocarbon B, but does not substantially contain a substance having a boiling point equal to or lower than the softening point of the thermoplastic resin, and the content of the substance is preferably 3% by weight with respect to the entire foaming agent 1. % Or less, more preferably 1% by weight or less, particularly preferably 0.5% by weight or less, and most preferably 0% by weight. The softening point of the thermoplastic resin is measured by the method shown in the following examples.
The substance having a boiling point below the softening point of the thermoplastic resin is not particularly limited, but representative examples thereof include propane, (iso) butane, (iso) pentane, (iso) hexane, (iso) heptane, (iso ) Hydrocarbons such as octane, (iso) nonane, (iso) decane (preferably hydrocarbons having 3 to 10 carbon atoms); halides thereof; fluorine-containing compounds such as hydrofluoroethers; compounds such as tetraalkylsilanes Can be mentioned. These compounds may be linear, branched or alicyclic, but of course, if they do not have a boiling point below the softening point of the thermoplastic resin, they will naturally have a boiling point below the softening point of the thermoplastic resin. Does not fall under substance.

The foaming agent 1 is a substance having a boiling point higher than the softening point of the thermoplastic resin, and does not belong to the hydrocarbon B, and is a substance that is vaporized by heating (hereinafter, may be referred to as another substance). You may contain.
Examples of other substances include (iso) decane, isobutylcyclohexane, butylcyclohexane, cyclodecane, normal-pentylcyclopentane, tert-butylcyclohexane, trans-1-isopropyl-4-methylcyclohexane, (iso) undecane, and amylcyclohexane. , (Iso) dodecane, 3-methylundecane, cyclododecane, hexylcyclohexane and other hydrocarbons having 10 to 12 carbon atoms, etc., but it is necessary that the material has a boiling point exceeding the softening point of the thermoplastic resin. is there. It is preferable that the foaming agent 1 contains a hydrocarbon having 12 carbon atoms such as (iso) dodecane as the other substance because the expansion start temperature can be lowered without decreasing the expansion ratio.

In the examples of substances having boiling points below the softening point of the above thermoplastic resin and other substances, there are compounds that are described redundantly, but once the softening point of the thermoplastic resin is determined, depending on the softening point, Will belong to either.
The blowing agent 2 contains both hydrocarbon A and hydrocarbon B. Examples of the hydrocarbon A include (iso) dodecane, 3-methylundecane, cyclododecane, hexylcyclohexane and the like.

The weight ratio of the hydrocarbon B to the foaming agent such as the foaming agent 1 and the foaming agent 2 is not particularly limited, but is preferably 90% by weight or less, more preferably 70% by weight or less, particularly preferably 50% by weight of the foaming agent. % Or less, most preferably 30% or less by weight. The lower limit of the weight ratio of hydrocarbon B is preferably 2% by weight. When the weight ratio of the hydrocarbon B is more than 90% by weight with respect to the blowing agent, the maximum expansion temperature is increased, but the expansion ratio may be decreased.
The weight ratio of hydrocarbon A to blowing agent 2 is not particularly limited, but is preferably 10% by weight or more, more preferably 30% by weight or more, particularly preferably 50% by weight or more, and most preferably 70% by weight or more. is there. The upper limit of the weight ratio of the hydrocarbon A is preferably 98% by weight. When the weight ratio of the hydrocarbon A is less than 10% by weight with respect to the foaming agent, the maximum expansion temperature increases, but the expansion ratio may decrease.

The encapsulating rate of the foaming agent encapsulated in the heat-expandable microspheres is not particularly limited, but is preferably 1 to 60% by weight, preferably 3 to 50% by weight, more preferably based on the weight of the heat-expandable microspheres. Is 8 to 40% by weight, particularly preferably 10 to 30% by weight.
Next, the thermoplastic resin is composed of a copolymer obtained by forming an outer shell and polymerizing a polymerizable component. Although there is no limitation in particular about the softening point of a thermoplastic resin, Preferably it is 120-260 degreeC, More preferably, it is 130-230 degreeC, Most preferably, it is 140-180 degreeC. When the softening point of the thermoplastic resin is less than 120 ° C., the heat resistance is low, so the expansion start temperature is low. On the other hand, when the softening point of the thermoplastic resin exceeds 260 ° C., the expansion start temperature and the maximum expansion temperature increase, but the expansion ratio may decrease.
The polymerizable component is a component that becomes a copolymer that is a thermoplastic resin that forms an outer shell by polymerization. The polymerizable component is a component which essentially includes a monomer component and may contain a crosslinking agent, and contains a carboxyl group-containing monomer as a monomer component as an essential component.

The monomer component generally includes a component called a (radical) polymerizable monomer having one polymerizable double bond. The monomer component requires a carboxyl group-containing monomer.
The carboxyl group-containing monomer is not particularly limited as long as it has one or more free carboxyl groups per molecule, but unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, and cinnamic acid. Acid; unsaturated dicarboxylic acid such as maleic acid, itaconic acid, fumaric acid, citraconic acid, chloromaleic acid; anhydride of unsaturated dicarboxylic acid; monomethyl maleate, monoethyl maleate, monobutyl maleate, monomethyl fumarate, fumaric acid And unsaturated dicarboxylic acid monoesters such as monoethyl, monomethyl itaconate, monoethyl itaconate and monobutyl itaconate. These carboxyl group-containing monomers may be used alone or in combination of two or more. In the carboxyl group-containing monomer, some or all of the carboxyl groups may be neutralized during polymerization or after polymerization. Among the carboxyl group-containing monomers, acrylic acid, methacrylic acid, maleic acid, maleic anhydride and itaconic acid are preferable, acrylic acid and methacrylic acid are more preferable, and methacrylic acid is particularly preferable because of high gas barrier properties. Hereinafter, acrylic acid or methacrylic acid may be collectively referred to as (meth) acrylic acid, and (meth) acryl means acrylic or methacrylic.

The monomer component may include a carboxyl group-containing monomer as an essential component, and one or more other monomer components may be used in combination. Other monomer components are not particularly limited. For example, nitrile monomers such as acrylonitrile, methacrylonitrile, and fumaronitrile; vinyl halide monomers such as vinyl chloride; halogenation such as vinylidene chloride Vinylidene monomers; vinyl ester monomers such as vinyl acetate, vinyl propionate and vinyl butyrate; methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) Acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, phenyl (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, etc. (Meta) Acu Luric acid ester monomers; (meth) acrylamide monomers such as acrylamide, substituted acrylamide, methacrylamide, and substituted methacrylamide; maleimide monomers such as N-phenylmaleimide and N-cyclohexylmaleimide; styrene, α -Styrene monomers such as methyl styrene; Ethylene unsaturated mono-olefin monomers such as ethylene, propylene and isobutylene; Vinyl ether monomers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether; Vinyl methyl ketone Examples thereof include vinyl ketone monomers such as N-vinyl carbazole, N-vinyl monomers such as N-vinyl pyrrolidone, and vinyl naphthalene salts.
Monomer components include nitrile monomers, (meth) acrylic acid ester monomers, styrene monomers, vinyl ester monomers, acrylamide monomers, and vinylidene halide monomers. It is preferable to further include at least one selected.

From the viewpoint that the weight ratio of the carboxyl group-containing monomer increases the heat resistance and solvent resistance of the thermally expandable microspheres, and lowers the expansion start temperature when heat treatment is performed at a temperature lower than the expansion start temperature. Preferably it is 10 to 90 weight% with respect to a monomer component, More preferably, it is 30 to 90 weight%, More preferably, it is 40 to 90 weight%, Especially preferably, it exceeds 51.2 weight% and 90 weight% The most preferred is 53 to 90% by weight. When the carboxyl group-containing monomer is less than 10% by weight, the heat resistance and solvent resistance are insufficient, and when the heat treatment is performed at a temperature lower than the expansion start temperature, the expansion start temperature is not sufficiently lowered. Sometimes. When the carboxyl group-containing monomer is more than 90% by weight, the expansion performance of the thermally expandable microspheres may be lowered.
When the monomer component further contains a nitrile monomer, it is preferable because the gas barrier property of the thermoplastic resin constituting the outer shell is improved.

When the nitrile monomer is included as an essential component, the weight ratio of the mixture of the carboxyl group-containing monomer and the nitrile monomer is preferably 50% by weight or more with respect to the monomer component, more preferably It is 60% by weight or more, more preferably 70% by weight or more, particularly preferably 80% by weight or more, and most preferably 90% by weight or more.
At this time, the mixing ratio of the carboxyl group-containing monomer in the mixture of the carboxyl group-containing monomer and the nitrile monomer is preferably 10 to 90% by weight, more preferably 30 to 90% by weight, still more preferably. It is 40 to 90% by weight, particularly preferably more than 51.2% by weight and 90% by weight or less, and most preferably 53 to 90% by weight. When the mixing ratio is less than 10% by weight, the heat resistance and solvent resistance are not sufficiently improved, and when the heat treatment is performed at a temperature lower than the expansion start temperature, the expansion start temperature may be insufficiently lowered. When the carboxyl group-containing monomer is more than 90% by weight, the expansion performance of the thermally expandable microspheres may be lowered.

When the monomer component contains a vinylidene chloride monomer, gas barrier properties are improved. Moreover, when the monomer component contains a (meth) acrylic acid ester monomer and / or a styrene monomer, the thermal expansion characteristics can be easily controlled. When the monomer component contains a (meth) acrylamide monomer, the heat resistance is improved.
The weight ratio of at least one selected from vinylidene chloride, (meth) acrylic acid ester monomer, (meth) acrylamide monomer, and styrene monomer is preferably 50 wt. %, More preferably less than 30% by weight, particularly preferably less than 10% by weight. If it is contained in an amount of 50% by weight or more, the heat resistance may be lowered.

The monomer component may contain a monomer that reacts with the carboxyl group of the carboxyl group-containing monomer. When the monomer component further contains a monomer that reacts with a carboxyl group, the heat resistance is further improved, and the expansion performance at a high temperature is improved. Examples of the monomer that reacts with the carboxyl group include N-methylol (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, vinyl glycidyl ether, and propenyl. Glycidyl ether, glycidyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, etc. Can be mentioned. The weight ratio of the monomer that reacts with the carboxyl group is preferably 0.1 to 10% by weight, more preferably 3 to 5% by weight, based on the monomer component.
The polymerizable component may contain a polymerizable monomer (crosslinking agent) having two or more polymerizable double bonds in addition to the monomer component. By polymerizing using a crosslinking agent, a decrease in the retention rate (encapsulation retention rate) of the encapsulated foaming agent at the time of thermal expansion is suppressed, and thermal expansion can be effectively performed.

Although it does not specifically limit as a crosslinking agent, For example, aromatic divinyl compounds, such as divinylbenzene; Allyl methacrylate, triacryl formal, triallyl isocyanate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, 1 , 4-butanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, PEG # 200 di (meth) acrylate, PEG # 600 di (meth) acrylate, trimethylolpropane trimethacrylate, pentaerythrul Examples include di (meth) acrylate compounds such as tall tri (meth) acrylate, dipentaerythritol hexaacrylate, and 2-butyl-2-ethyl-1,3-propanediol diacrylate. These crosslinking agents may be used alone or in combination of two or more.
The amount of the crosslinking agent is not particularly limited, but is preferably 0.01 to 5 parts by weight, more preferably 0.1 to 1 part by weight, and particularly preferably 0. More than 2 parts by weight and less than 1 part by weight. The amount of the crosslinking agent may be 0 part by weight or more and less than 0.1 part by weight with respect to 100 parts by weight of the monomer component.

  The weight ratio of the carboxyl group-containing monomer in the polymerizable component increases the heat resistance and solvent resistance of the resulting heat-expandable microspheres. From the viewpoint of lowering, it is preferably 10% by weight or more, more preferably 30% by weight or more, further preferably 40% by weight or more, particularly preferably more than 50% by weight, and most preferably 53% by weight or more. The upper limit of the weight ratio is preferably 90% by weight. If it is less than 10% by weight, the heat resistance and solvent resistance are insufficient, and when the heat treatment is performed at a temperature lower than the expansion start temperature, the expansion start temperature may be insufficiently lowered. If it exceeds 90% by weight, the expansion ratio may decrease.

[Method for producing thermally expandable microspheres]
Next, a method for producing thermally expandable microspheres will be described. The method for producing thermally expandable microspheres is a step of polymerizing a polymerizable component in an aqueous dispersion medium in which an oily mixture containing a polymerizable component and a blowing agent described in detail above is dispersed (hereinafter referred to as a polymerization step). There is a method.
In the polymerization step, it is preferable to polymerize the polymerizable component in the presence of the polymerization initiator using an oily mixture containing a polymerization initiator.

Although there is no limitation in particular as a polymerization initiator, A peroxide, an azo compound, etc. can be mentioned.
Examples of the peroxide include diisopropyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, di-2-octyl peroxydicarbonate, and dibenzyl peroxydicarbonate. Peroxydicarbonates such as t-butyl peroxypivalate, t-hexyl peroxypivalate, 1-cyclohexyl-1-methylethylperoxyneodecanoate, t-butylperoxy 3,5,5-trimethyl Examples thereof include peroxyesters such as hexanoate; diacyl peroxides such as lauroyl peroxide and benzoyl peroxide.

Examples of the azo compound include 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4- Dimethylvaleronitrile), 2,2'-azobis (2-methylpropionate), 2,2'-azobis (2-methylbutyronitrile), and the like. These polymerization initiators may be used alone or in combination of two or more. As the polymerization initiator, an oil-soluble polymerization initiator soluble in the monomer component is preferable. Among the polymerization initiators, peroxydicarbonate is preferable. When the polymerization initiator includes other initiators together with peroxydicarbonate, the proportion of peroxydicarbonate in the polymerization initiator is preferably 60% by weight or more.
Although there is no limitation in particular about the quantity of a polymerization initiator, it is preferable in it being 0.3-8.0 weight part with respect to 100 weight part of said monomer components.

In the polymerization step, the oily mixture may further contain a chain transfer agent and the like.
The aqueous dispersion medium is a medium mainly composed of water such as ion-exchanged water in which the oily mixture is dispersed, and may further contain an alcohol such as methanol, ethanol or propanol, or a hydrophilic organic solvent such as acetone. Good. The hydrophilicity in the present invention means that it can be arbitrarily mixed with water. Although there is no limitation in particular about the usage-amount of an aqueous dispersion medium, it is preferable to use 100-1000 weight part aqueous dispersion medium with respect to 100 weight part of polymeric components.

The aqueous dispersion medium may further contain an electrolyte. Examples of the electrolyte include sodium chloride, magnesium chloride, calcium chloride, sodium sulfate, magnesium sulfate, ammonium sulfate, and sodium carbonate. These electrolytes may be used alone or in combination of two or more. Although there is no limitation in particular about content of an electrolyte, it is preferable to contain 0.1-50 weight part with respect to 100 weight part of aqueous dispersion media.
An aqueous dispersion medium is a water-soluble 1,1-substituted compound having a structure in which a hydrophilic functional group selected from a hydroxyl group, a carboxylic acid (salt) group, and a phosphonic acid (salt) group and a hetero atom are bonded to the same carbon atom , Potassium dichromate, alkali metal nitrite, metal (III) halide, boric acid, water-soluble ascorbic acids, water-soluble polyphenols, water-soluble vitamin Bs and water-soluble phosphonic acids (salts) It may contain at least one water-soluble compound. In addition, the water solubility in this invention means the state which melt | dissolves 1g or more per 100g of water.

The amount of the water-soluble compound contained in the aqueous dispersion medium is not particularly limited, but is preferably 0.0001 to 1.0 part by weight, more preferably 0.0003 to 100 parts by weight of the polymerizable component. 0.1 parts by weight, particularly preferably 0.001 to 0.05 parts by weight. If the amount of the water-soluble compound is too small, the effect of the water-soluble compound may not be sufficiently obtained. Moreover, when there is too much quantity of a water-soluble compound, a polymerization rate may fall or the residual amount of the polymeric component which is a raw material may increase.
The aqueous dispersion medium may contain a dispersion stabilizer and a dispersion stabilization auxiliary agent in addition to the electrolyte and the water-soluble compound.

The dispersion stabilizer is not particularly limited, and examples thereof include tricalcium phosphate, magnesium pyrophosphate, calcium pyrophosphate obtained by a metathesis generation method, colloidal silica, alumina sol, and the like. These dispersion stabilizers may be used alone or in combination of two or more.
The blending amount of the dispersion stabilizer is preferably 0.1 to 20 parts by weight, more preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the polymerizable component.

The dispersion stabilizing aid is not particularly limited, and examples thereof include a polymer type dispersion stabilizing aid, a cationic surfactant, an anionic surfactant, an amphoteric surfactant, and a nonionic surfactant. Mention may be made of activators. These dispersion stabilizing aids may be used alone or in combination of two or more.
The aqueous dispersion medium is prepared, for example, by blending water (ion-exchanged water) with a water-soluble compound and, if necessary, a dispersion stabilizer and / or a dispersion stabilizing aid. The pH of the aqueous dispersion medium at the time of polymerization is appropriately determined depending on the type of water-soluble compound, dispersion stabilizer, and dispersion stabilization aid.

In the polymerization step, polymerization may be performed in the presence of sodium hydroxide, sodium hydroxide and zinc chloride.
In the polymerization step, the oily mixture is emulsified and dispersed in an aqueous dispersion medium so that spherical oil droplets having a predetermined particle diameter are prepared.

Examples of the method for emulsifying and dispersing the oily mixture include, for example, a method of stirring with a homomixer (for example, manufactured by Tokushu Kika Kogyo Co., Ltd.) and the like, and a static dispersion device such as a static mixer (for example, manufactured by Noritake Engineering Co., Ltd.). And general dispersion methods such as a method using a film, a membrane emulsification method, and an ultrasonic dispersion method.
Next, suspension polymerization is started by heating the dispersion in which the oily mixture is dispersed as spherical oil droplets in the aqueous dispersion medium. During the polymerization reaction, it is preferable to stir the dispersion, and the stirring may be performed so gently as to prevent, for example, floating of the monomer and sedimentation of the thermally expandable microspheres after polymerization.

  Although superposition | polymerization temperature is freely set by the kind of polymerization initiator, Preferably it is 30-100 degreeC, More preferably, it controls in the range of 40-90 degreeC. The time for maintaining the reaction temperature is preferably about 0.1 to 20 hours. Although there is no limitation in particular about the superposition | polymerization initial pressure, it is the range of 0-5.0 MPa by gauge pressure, More preferably, it is the range of 0.1-3.0 MPa.

[Thermal expandable microsphere and its use]
The hollow fine particles of the present invention can be produced by heating and expanding the heat-expandable microspheres of the present invention described above. Here, the thermally expandable microsphere of the present invention may be obtained by the method for producing a thermally expandable microsphere described above. The method of heating expansion is not particularly limited, and any of a dry heating expansion method and a wet heating expansion method may be used.
Examples of the dry heating expansion method include a method described in JP-A-2006-213930, particularly an internal injection method. As another dry heating expansion method, there is a method described in JP-A-2006-96963. Examples of the wet heating expansion method include the method described in JP-A No. 62-201231.

Although there is no limitation in particular about the average particle diameter of a hollow microparticle, Preferably it is 1-1000 micrometers, More preferably, it is 5-800 micrometers, Most preferably, it is 10-500 micrometers. Further, the coefficient of variation CV of the particle size distribution of the hollow fine particles is not particularly limited, but is preferably 30% or less, more preferably 27% or less, and particularly preferably 25% or less.
The composition of the present invention includes at least one granular material selected from the thermally expandable microspheres of the present invention and the hollow fine particles of the present invention, and a base material component. Here, the thermally expandable microsphere of the present invention may be obtained by the method for producing a thermally expandable microsphere described above.

The base material component is not particularly limited. For example, rubbers such as natural rubber, butyl rubber, silicon rubber, ethylene-propylene-diene rubber (EPDM); thermosetting resins such as epoxy resin and phenol resin; polyethylene wax, paraffin Waxes such as wax; ethylene-vinyl acetate copolymer (EVA), polyethylene, polypropylene, polyvinyl chloride (PVC), acrylic resin, thermoplastic polyurethane, acrylonitrile-styrene copolymer (AS resin), acrylonitrile-butadiene- Styrene copolymer (ABS resin), polystyrene (PS), polyamide resin (nylon 6, nylon 66, etc.), polycarbonate, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyacetal (POM) Thermoplastic resins such as polyphenylene sulfide (PPS); Ionomer resins such as ethylene ionomer, urethane ionomer, styrene ionomer, and fluorine ionomer; Thermoplastic elastomers such as olefin elastomer and styrene elastomer; Polylactic acid (PLA) Bioplastics such as cellulose acetate, PBS, PHA, starch resin, etc .; Sealing materials such as modified silicone, urethane, polysulfide, acrylic, silicone, polyisobutylene, butyl rubber; urethane, ethylene-vinyl acetate Polymer-based, vinyl chloride-based, acrylic-based paint components; inorganic materials such as cement, mortar, and cordierite.
The composition of the present invention can be prepared by mixing these base material components with thermally expandable microspheres and / or hollow fine particles.

Examples of the use of the composition of the present invention include a molding composition, a coating composition, a clay composition, a fiber composition, an adhesive composition, and a powder composition.
The composition of the present invention is a compound having a melting point lower than the expansion start temperature of the thermally expandable microsphere and / or a thermoplastic resin (for example, polyethylene wax, paraffin wax, in particular, as a base component together with the thermally expandable microsphere. Waxes such as ethylene-vinyl acetate copolymer (EVA), polyethylene, polypropylene, polyvinyl chloride (PVC), acrylic resin, thermoplastic polyurethane, acrylonitrile-styrene copolymer (AS resin), acrylonitrile-butadiene-styrene Thermoplastic resins such as copolymer (ABS resin), polystyrene (PS), polycarbonate, polyethylene terephthalate (PET), polybutylene terephthalate (PBT); ethylene ionomer, urethane ionomer, styrene ionomer, fluorine Ionomer resins such as ionomer; may include olefinic elastomers, thermoplastic elastomers) such as styrene elastomer can be used as a master batch for a resin molded. In this case, this resin molding masterbatch composition is used for injection molding, extrusion molding, press molding, and the like, and is suitably used for introducing bubbles during resin molding. The resin used at the time of resin molding is not particularly limited as long as it is selected from the above base material components. For example, ethylene-vinyl acetate copolymer (EVA), polyethylene, polypropylene, polyvinyl chloride (PVC), acrylic resin , Thermoplastic polyurethane, acrylonitrile-styrene copolymer (AS resin), acrylonitrile-butadiene-styrene copolymer (ABS resin), polystyrene (PS), polyamide resin (nylon 6, nylon 66, etc.), polycarbonate, polyethylene terephthalate ( PET), polybutylene terephthalate (PBT), ionomer resin, polyacetal (POM), polyphenylene sulfide (PPS), olefin elastomer, styrene elastomer, polylactic acid (PLA), cellulose acetate, P S, PHA, starch resins, natural rubber, butyl rubber, silicone rubber, ethylene - propylene - diene rubber (EPDM), etc., and, mixtures thereof and the like. Moreover, you may contain reinforcing fibers, such as glass fiber and carbon fiber.

The molded product of the present invention is obtained by molding this composition. Examples of the molded article of the present invention include molded articles such as molded articles and coating films. In the molded product of the present invention, various physical properties such as lightness, porosity, sound absorption, heat insulation, low thermal conductivity, low dielectric constant, design, impact absorption, and strength are improved.
A ceramic filter or the like can be obtained by further firing a molded product containing an inorganic substance as a base component.

Below, the Example of the thermally expansible microsphere of this invention is described concretely. The present invention is not limited to these examples. In the following Examples and Comparative Examples, “%” means “% by weight” unless otherwise specified.
About the thermally expansible microsphere quoted by the following example and the comparative example, the physical property was measured in the way shown next, and also performance was evaluated. Hereinafter, the heat-expandable microsphere may be referred to as “microsphere” for simplicity.

[Measurement of average particle size and particle size distribution]
A laser diffraction particle size distribution analyzer (HEROS & RODOS manufactured by SYMPATEC) was used. The dispersion pressure of the dry dispersion unit was 5.0 bar and the degree of vacuum was 5.0 mbar, measured by a dry measurement method, and the D50 value was taken as the average particle size.

[Measurement of moisture content of microspheres]
As a measuring apparatus, a Karl Fischer moisture meter (MKA-510N type, manufactured by Kyoto Electronics Industry Co., Ltd.) was used for measurement.

[Measurement of encapsulation rate of foaming agent enclosed in microspheres]
1.0 g of microspheres were placed in a stainless steel evaporation dish having a diameter of 80 mm and a depth of 15 mm, and the weight (W ₁ ) was measured. Add 30 ml of acetonitrile, disperse it uniformly, leave it at room temperature for 30 minutes, and then dry it for 2 hours at 150 ° C. and 0.1 kPa using a vacuum dryer (manufactured by Yamato Kagaku Co., DP43). The weight (W ₂ ) of was measured. The encapsulation rate of the foaming agent is calculated by the following formula.
Inclusion rate (% by weight) = (W ₁ −W ₂ ) (g) /1.0 (g) × 100− (water content) (% by weight)
(In the formula, the moisture content is measured by the above method.)

[Measurement of expansion start temperature (Ts1) and maximum expansion temperature (Tmax1)]
As a measuring device, DMA (DMA Q800 type, manufactured by TA instruments) was used. Place 0.5 mg of microspheres in an aluminum cup with a diameter of 6.0 mm (inner diameter 5.65 mm) and a depth of 4.8 mm, and place an aluminum lid (diameter 5.6 mm, thickness 0.1 mm) on top of the microsphere layer. A sample was prepared. The sample height was measured in a state where a force of 0.01 N was applied to the sample with a pressurizer from above. In a state where a force of 0.01 N was applied by the pressurizer, heating was performed from 20 ° C. to 350 ° C. at a rate of temperature increase of 10 ° C./min, and the displacement of the pressurizer in the vertical direction was measured. The displacement start temperature in the positive direction was defined as the expansion start temperature (Ts1), and the temperature when the maximum displacement was indicated was defined as the maximum expansion temperature (Tmax1).
[Measurement of expansion start temperature (Ts2) and maximum expansion temperature (Tmax2) after heat treatment]
A flat box with a bottom surface of 12 cm in length, 13 cm in width and 9 cm in height is made of aluminum foil, and 1.0 g of microspheres are uniformly placed therein, placed in a gear-type oven, and a predetermined heating temperature ( With respect to the microspheres heated at T) for 5 minutes, the expansion start temperature (Ts2) and the maximum expansion temperature (Tmax2) were measured by the measurement method described above.

[Calculation of expansion rate variation rate (ΔTs) and maximum expansion temperature variation rate (ΔTmax)]
Using Ts1 and Ts2 obtained by the above method, and Tmax1 and Tmax2, the fluctuation rate of expansion start temperature (ΔTs) and the fluctuation rate of maximum expansion temperature (ΔTmax) before and after the heat treatment were calculated by the following equations.
ΔTs = [(Ts1−Ts2) / Ts1] × 100
ΔTmax = [(Tmax1-Tmax2) / Tmax1] × 100

[Measurement of softening point of thermoplastic resin]
Place 1.0 g of microspheres in a stainless steel evaporating dish with a diameter of 80 mm and a depth of 15 mm, add 30 ml of acetonitrile, disperse it uniformly, leave it at room temperature for 30 minutes, and then use a vacuum dryer (manufactured by Yamato Kagaku Co., DP43). And a sample which does not contain a foaming agent is obtained by making it dry on 150 degreeC and 0.1 kPa conditions for 2 hours.
Using DMA (DMA Q800 type, manufactured by TA instruments) as a measuring device, about 10 mg of a sample is put in an aluminum cup having a diameter of 6.0 mm (inner diameter 5.65 mm) and a depth of 4.8 mm, and the upper part of the sample layer. A sample was prepared by placing an aluminum lid (diameter 5.6 mm, thickness 0.1 mm) on. The sample height was measured in a state where a force of 0.01 N was applied to the sample with a pressurizer from above. In a state where a force of 0.01 N was applied by a pressurizer, heating was performed from 20 ° C. to 350 ° C. at a rate of temperature increase of 10 ° C./min, and the position of the pressurizer in the vertical direction was measured.
A DMA curve in which the heating temperature and the position of the pressurizer in the vertical direction are plotted is shown in FIG. The method for determining the softening point of the thermoplastic resin from FIG. 2 is as follows. First, in the DMA curve of FIG. 2, a straight line m is drawn in a state where there is no (almost) change in the position in the vertical direction of the pressurizer at the beginning of the temperature rise. Next, a tangent line n drawn at a point where the gradient of the curve of the stepped portion where the position of the pressurizer in the vertical direction has changed due to softening of the thermoplastic resin is maximized is drawn. And the heating temperature in the intersection P of the straight line m and the tangent n is defined as the softening point of a thermoplastic resin.

[Example 1]
To 600 g of ion-exchanged water, 150 g of sodium chloride, 50 g of colloidal silica that is 20% by weight of silica active ingredient, 1.0 g of polyvinyl pyrrolidone, and 0.5 g of ethylenediaminetetraacetic acid / 4Na salt were added. The pH was adjusted to 2.8 to 3.2 to prepare an aqueous dispersion medium.
Separately, 45 g of acrylonitrile, 120 g of methacrylonitrile, 135 g of methacrylic acid, 1.0 g of trimethylolpropane trimethacrylate, 72 g of isododecane, 8 g of isohexadecane, and di-sec-butylperoxydicarbonate containing 50% active ingredient 8 g of the liquid was mixed to prepare an oily mixture.
The aqueous dispersion medium and the oily mixture were mixed, and the obtained mixed liquid was dispersed with a homomixer (TK machine manufactured by Tokushu Kika Kogyo Co., Ltd.) to prepare a suspension. The suspension was transferred to a pressure reactor with a capacity of 1.5 liters, purged with nitrogen, then brought to an initial reaction pressure of 0.5 MPa, and polymerized at a polymerization temperature of 60 ° C. for 20 hours while stirring at 80 rpm. The product was filtered and dried to obtain thermally expandable microspheres. The physical properties are shown in Table 1.

[Examples 2 to 6]
Thermally expandable microspheres were obtained in the same manner as in Example 1 except that the various components and amounts used in Example 1 were changed to those shown in Table 1. Table 1 shows the physical properties of the obtained thermally expandable microspheres.
The thermally expandable microspheres obtained in Examples 1 to 6 are referred to as microspheres (1) to (6), respectively.

[Comparative Example 1]
To 565 g of ion-exchanged water, 177 g of sodium chloride, 40 g of colloidal silica which is 20% by weight of silica active ingredient, 1.6 g of 50% by weight diethanolamine-adipic acid condensate (acid value = 78 mgKOH / g), and sodium nitrite After adding 12 g, the pH of the resulting mixture was adjusted to 2.8 to 3.2 to prepare an aqueous dispersion medium.
Separately, 88 g of methacrylonitrile, 112 g of methacrylic acid, 60 g of isooctane and 2 g of 2,2-azobisisobutyronitrile were mixed to prepare an oily mixture.
The aqueous dispersion medium and the oily mixture were mixed, and the obtained mixed liquid was dispersed with a homomixer (TK machine manufactured by Tokushu Kika Kogyo Co., Ltd.) to prepare a suspension. This suspension was transferred to a 1.5 liter pressurized reactor and purged with nitrogen, then the reaction was brought to an initial reaction pressure of 0.5 MPa, stirred at 80 rpm for 15 hours at a polymerization temperature of 60 ° C., and further at 70 ° C. for 9 hours. Polymerized for hours. The obtained product was filtered and dried to obtain thermally expandable microspheres. The physical properties are shown in Table 1.

[Comparative Example 2]
To 555 g of ion-exchanged water, 177 g of sodium chloride, 65 g of colloidal silica which is 20% by weight of silica active ingredient, 6.5 g of 50% by weight diethanolamine-adipic acid condensate (acid value = 78 mgKOH / g), 0.24 g of sodium nitrite and After adding 0.04 g of stannous chloride, the pH of the resulting mixture was adjusted to 2.8 to 3.2 to prepare an aqueous dispersion medium.
Separately from this, the same oily mixture as in Comparative Example 1 was prepared and polymerized in the same manner as in Comparative Example 1 to obtain thermally expandable microspheres. The physical properties are shown in Table 1.
The thermally expandable microspheres obtained in Comparative Examples 1 and 2 are referred to as comparative microspheres (1) and (2), respectively.

  In Table 1 above, the abbreviations shown in Table 2 are used.

[Example A1]
(Preparation of masterbatch)
After uniformly mixing 500 g of microspheres (2) obtained in Example 2 and 25 g of process oil (Kyoishi Process P-200, manufactured by Nikko Kyoishi Co., Ltd.), ABS resin (manufactured by Denki Kagaku Kogyo Co., Ltd., GS-10, (Specific gravity 1.04) 475 g was added and mixed uniformly to prepare a resin mixture.
Next, using a lab plast mill (manufactured by Toyo Seiki Co., Ltd., ME-25, twin-screw extruder) and a strand-die (caliber: 1.5 mm), cylinder temperature C1: 220 ° C-C2: 220 ° C-C3: 220 ° C.-Strand-Die: set to 220 ° C., screw speed set to 40 rpm, the resin mixture is fed from a raw material hopper of a lab plast mill, kneaded and extruded, pelletized by a pelletizer, and master batch pellet A1 (The content of thermally expandable microspheres was 50 wt%). The appearance of the pellet was good because the thermally expandable microspheres were not expanded.

(injection molding)
6 parts by weight of the master batch pellet A1 and 100 parts by weight of ABS resin (manufactured by Denki Kagaku Kogyo Co., Ltd., GS-10, specific gravity 1.04) are mixed, and the resulting mixed pellets are screw pre-plastic injection molding machine ( It was supplied to a hopper manufactured by Sodick, Tupar TR80S2A, mold clamping force 80 tons), melted and kneaded, and injection molded to obtain a plate-shaped molded body. The molding conditions were set at a plasticizing part temperature: 220 ° C., an injection speed: 70 mm / sec, a mold temperature: 50 ° C., and injection molding was performed at 220 ° C., 230 ° C., 240 ° C., and 250 ° C., respectively. Carried out. The specific gravity of the obtained molded product was 0.65 at 220 ° C., 0.63 at 230 ° C., 0.61 at 240 ° C., and 0.61 at 250 ° C., respectively.

[Comparative Example A1]
A master batch was prepared in the same manner as in Example A1, except that in Example A1, the microsphere (2) was changed to the comparative microsphere (2) obtained in Comparative Example 2. However, since the thermally expandable microspheres expanded, master batch pellets could not be obtained, and molded products could not be obtained.

1 Outer shell made of thermoplastic resin 2 Foaming agent

As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be achieved with carboxylic acid-based thermally expandable microspheres containing a specific foaming agent, and have reached the present invention.
That is, the thermally expandable microsphere according to the present invention is a thermally expandable microsphere composed of an outer shell made of a thermoplastic resin and a foaming agent encapsulated therein and vaporized by heating. The plastic resin is composed of a copolymer obtained by polymerizing a polymerizable component containing a carboxyl group-containing monomer and a nitrile monomer, and the nitrile monomer is acrylonitrile and / or methacrylonitrile. It is a thermally expandable microsphere.

Here, the foaming agent satisfies the following.
The foaming agent contains a hydrocarbon A having 12 carbon atoms and a hydrocarbon B having 13 or more carbon atoms , the encapsulation rate of the foaming agent with respect to the thermally expandable microspheres is 1 to 60% by weight, and the weight of the hydrocarbon B The ratio is 70% by weight or less of the foaming agent.

Claims (8)

A thermally expandable microsphere composed of an outer shell made of a thermoplastic resin and a foaming agent contained therein and vaporized by heating;
The thermoplastic resin is composed of a copolymer obtained by polymerizing a polymerizable component containing a carboxyl group-containing monomer,
The blowing agent includes a hydrocarbon A having 12 carbon atoms and a hydrocarbon B having 13 or more carbon atoms,
Thermally expandable microspheres.   The thermally expansible microsphere of Claim 1 whose weight ratio of the said hydrocarbon B is 90 weight% or less of a foaming agent. The expansion start temperature of the thermally expandable microsphere is Ts1 (° C.), and the expansion start temperature after heat treatment of the thermally expandable microsphere for 5 minutes is Ts2 (° C.) at T (° C.) satisfying the following formula (A). ), The thermal expansion microspheres according to claim 1 or 2, wherein a reduction rate (ΔTs) of the expansion start temperature defined by the following calculation formula (B) is more than 3%.
170 ≦ T <Ts1 (A)
ΔTs = [(Ts1−Ts2) / Ts1] × 100 (%) (B)   The thermal expansion microsphere according to any one of claims 1 to 3, wherein the expansion start temperature is 180 ° C or higher.   The thermally expandable microsphere according to any one of claims 1 to 4, wherein the polymerizable component further contains a nitrile monomer.   Hollow fine particles obtained by heating and expanding the thermally expandable microspheres according to any one of claims 1 to 5.   A composition comprising at least one granular material selected from the thermally expandable microspheres according to any one of claims 1 to 5 and the hollow fine particles according to claim 6, and a base material component.   A molded product obtained by molding the composition according to claim 7.

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