JP2010215712A - Binder resin and paste composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a binder resin comprising an acrylic block copolymer comprising a methacrylic polymer block and a (meth)acrylic polymer block, and to provide a paste composition using the binder resin. <P>SOLUTION: The binder resin comprises an acrylic block copolymer comprising 10 to 90 wt.% of methacrylic polymer blocks (A) and 90 to 10 wt.% of (meth)acrylic polymer blocks (B), wherein the glass transition temperature of the methacrylic polymer blocks (A) is higher than the glass transition temperature of the (meth)acrylic polymer blocks (B), a number average molecular weight is 10,000 to 100,000, a molecular distribution (Mw/Mn) is ≤1.8, and a thixotropy index (viscosity (25°C) under 2 rpm rotation/viscosity (25°C) under 20 rpm rotation) when dissolved in toluene in 40 wt.% concentration, is 1.5 to 5.5. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a binder resin comprising an acrylic block copolymer and a paste composition using the binder resin.

  In recent years, it has been generally performed to obtain a precise molded body by molding a paste in which inorganic particles are dispersed in a binder resin, followed by firing.

  For example, a multilayer ceramic capacitor is manufactured through the following processes.

  First, after adding a solvent, a plasticizer, a dispersant and the like to the binder resin, a ceramic raw material powder is added, and the mixture is uniformly mixed and defoamed to obtain a ceramic paste having a constant viscosity. After this ceramic paste is formed into a sheet, a ceramic green sheet is obtained by removing the solvent by heating or the like.

  Next, a conductive paste to be an internal electrode is applied on the ceramic green sheet by screen printing or the like. A laminated body is obtained by laminating ceramic green sheets coated with a conductive paste and thermocompression bonding. The conductive paste is composed of metal particles and a binder resin.

  The binder resin, which is a component of the ceramic green sheet and the conductive paste, is thermally decomposed by heating and fired to obtain a fired ceramic product. A multilayer ceramic capacitor is manufactured by sintering an external electrode on the end face of the ceramic fired product.

  Thus, although binder resin is used for ceramic paste, conductive paste, and the like, cellulose resin, acrylic resin, and the like are generally used as binder resin (Patent Documents 1, 2, and 3). Acrylic resins have better thermal decomposability than cellulose resins, but have poor printability due to poor thixotropy.

  On the other hand, a binder resin made of an acrylic resin containing a polar functional group such as a hydroxyl group is known (Patent Document 4), and although it has improved printability, it cannot be said that it is sufficient yet. Development of an excellent binder resin is desired.

JP2008-50594 JP2007-277442A JP-A-5-58711 JP2008-202041

  Provided are a binder resin comprising an acrylic block copolymer comprising a methacrylic polymer block (A) and a (meth) acrylic polymer block (B), and a paste composition using the binder resin.

  As a result of intensive studies to solve the above problems, the present inventor has completed the present invention.

  That is, the present invention is an acrylic block copolymer comprising a methacrylic polymer block (A) of 10 to 90% by weight and a (meth) acrylic polymer block (B) of 90 to 10% by weight. The glass transition temperature of the polymer block (A) is higher than the glass transition temperature of the (meth) acrylic polymer block (B), the number average molecular weight is 10,000 to 100,000, and the molecular weight distribution is 1.8 or less. And a thixo index (viscosity at 2 rpm (25 ° C.) / Viscosity at 20 rpm (25 ° C.)) of 1.5 to 5.5 when dissolved in 40% by weight of toluene It relates to resin.

  As a preferred embodiment, the acrylic block copolymer has a weight loss of 95% or more when heated to 500 ° C. under a nitrogen atmosphere at a heating rate of 10.0 ° C./min. It relates to a binder resin.

  In a preferred embodiment, the acrylic block copolymer has a carboxyl group, an acid anhydride group, a hydroxyl group, at least one of the methacrylic polymer block (A) and the (meth) acrylic polymer block (B). The present invention relates to a binder resin having at least one functional group (C) selected from the group consisting of epoxy groups.

  A preferred embodiment relates to a binder resin wherein the functional group (C) is a carboxyl group or a hydroxyl group.

  A preferred embodiment relates to a binder resin characterized in that the content of the functional group (C) is 5% by weight or less in the acrylic block copolymer.

  As a preferred embodiment, the present invention relates to a binder resin characterized in that an acrylic block copolymer is produced by controlled radical polymerization.

  As a preferred embodiment, the present invention relates to a binder resin characterized in that an acrylic block copolymer is produced by atom transfer radical polymerization.

  The present invention further relates to a paste composition comprising the binder resin described above and inorganic particles.

  As a preferred embodiment, the present invention relates to a paste composition characterized in that the inorganic particles are conductive particles.

  A preferred embodiment relates to a paste composition characterized in that the inorganic particles are metal particles.

  A preferred embodiment relates to a paste composition characterized in that the inorganic particles are ceramic particles.

  INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a binder resin excellent in thermal decomposability, excellent in balance of dispersibility, viscosity, thixotropy and spinnability, and can provide a paste composition excellent in printability. .

Hereinafter, the present invention will be described in more detail.
<Acrylic block copolymer>
The acrylic block copolymer constituting the binder resin of the present invention comprises a methacrylic polymer block (A) mainly composed of methacrylic acid ester and a (meth) acrylic heavy polymer mainly composed of (meth) acrylic acid ester. It is an acrylic block copolymer composed of a combined block (B). Here, (meth) acryl means methacryl or acryl. An acrylic block copolymer comprising 10 to 90% by weight of the methacrylic polymer block (A) and 90 to 10% by weight of the (meth) acrylic polymer block (B) is preferable.

  The structure of the acrylic block copolymer may be either a linear block copolymer, a branched (star) block copolymer, or a mixture thereof. The structure of such a block copolymer is appropriately selected according to the required physical properties of the acrylic block copolymer, but a linear block copolymer is preferable in terms of cost and ease of polymerization. .

  The linear block copolymer may have any structure. From the viewpoint of the physical properties of the linear block copolymer and the physical properties of the composition, the methacrylic polymer block (A) is converted to a, (meta ) When the acrylic polymer block (B) is expressed as b, (ab) n type, b- (ab) n type and (ab) na type (n is an integer of 1 or more) For example, it is preferably made of at least one acrylic block copolymer selected from the group consisting of 1 to 3). Among these, an ab type diblock copolymer, an abb type triblock copolymer, or a mixture thereof is preferable from the viewpoint of easy handling during processing and physical properties of the composition.

  The number average molecular weight (Mn) of the acrylic block copolymer constituting the binder resin of the present invention is preferably 10,000 to 100,000. If the number average molecular weight is less than 10,000, the viscosity of the paste composition becomes too low, which causes dripping or poor thixotropy. When the number average molecular weight is greater than 100,000, the viscosity becomes too high, and the workability and printability tend to be reduced, and the spinnability (threading) tends to deteriorate. In addition, the said number average molecular weight shows the value measured by polystyrene conversion by the gel permeation chromatography (GPC) which uses chloroform as a mobile phase and uses a polystyrene gel column.

  The ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the acrylic block copolymer measured by GPC is not particularly limited, but is preferably 1.8 or less. When Mw / Mn exceeds 1.8, the physical properties may deteriorate due to an increase in low molecular weight components that cause sagging and high molecular weight components that cause high viscosity.

  The ratio of the methacrylic polymer block (A) in the acrylic block copolymer is 10 to 90% by weight. If the amount is less than 10% by weight, sagging of the paste composition becomes a problem, and if it is 90% by weight or more, the viscosity of the paste composition may become too high.

The relationship between the glass transition temperature of the methacrylic polymer block (A) and the (meth) acrylic polymer block (B) constituting the acrylic block copolymer is the same as that of the methacrylic polymer block (A). TgA, the (meth) acrylic polymer block (B) is defined as TgB, and the following relationship is satisfied. In particular, the difference between TgA and TgB is preferably 50 ° C. or more from the viewpoint of thixotropy.
TgA> TgB
The glass transition temperature (Tg) of the polymer can be set by setting the monomer weight ratio of each polymer portion according to the following Fox equation.
1 / Tg = (W1 / Tg1) + (W2 / Tg2) + ... + (Wm / Tgm)
W1 + W2 + ... + Wm = 1
In the formula, Tg represents the glass transition temperature of the polymer portion, and Tg1, Tg2,..., Tgm represent the glass transition temperature of each polymerization monomer. W1, W2,..., Wm represent the weight ratio of each polymerization monomer.

  As the glass transition temperature of each polymerization monomer in the Fox formula, for example, the value described in Polymer Handbook Third Edition (Wiley-Interscience, 1989) may be used.

  The glass transition temperature can be measured by DSC (differential scanning calorimetry) or tan δ peak of dynamic viscoelasticity.

  The acrylic block copolymer constituting the binder resin of the present invention has a weight loss of 95% or more when the temperature is raised to 500 ° C. under a nitrogen atmosphere at a heating rate of 10.0 ° C./min. Features. If it is less than 95%, the residue increases after firing, which is not preferable.

  The acrylic block copolymer constituting the binder resin of the present invention has a thixo index (viscosity at 2 rpm (25 ° C.) / Viscosity at 20 rpm (25 ° C.)) of 40% by weight dissolved in toluene. It is 5 to 5.5. When the thixo index is outside this range, there may be a problem such as a decrease in screen printability or dripping of the paste composition at a high temperature.

<Methacrylic polymer block (A)>
The methacrylic polymer block (A) is a block formed by polymerizing a monomer having a methacrylic acid ester as a main component. Here, the main component means that 50% by weight or more of the monomers constituting the methacrylic polymer block (A) is a methacrylic ester. If it is less than 50% by weight, the thermal decomposability tends to decrease.

  Examples of the methacrylic acid ester include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, isobutyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, Methacrylic acid aliphatic hydrocarbons such as n-heptyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, nonyl methacrylate, decyl methacrylate, dodecyl methacrylate, stearyl methacrylate, etc. (for example, alkyl having 1 to 18 carbon atoms) ) Ester; Methacrylic acid alicyclic hydrocarbon ester such as cyclohexyl methacrylate and isobornyl methacrylate; Aralkyl methacrylate such as benzyl methacrylate; Phenyl methacrylate, Tolu methacrylate Methacrylic acid aromatic hydrocarbon esters such as dimethyl ether; esters of methacrylic acid such as 2-methoxyethyl methacrylate and 3-methoxybutyl methacrylate with functional group-containing alcohols having etheric oxygen; trifluoromethyl methacrylate, methacrylic acid Trifluoromethyl methyl, 2-trifluoromethyl ethyl methacrylate, 2-trifluoroethyl methacrylate, 2-perfluoroethyl ethyl methacrylate, 2-perfluoroethyl-2-perfluorobutyl ethyl methacrylate, 2-methacrylic acid 2- Perfluoroethyl, perfluoromethyl methacrylate, diperfluoromethyl methyl methacrylate, 2-perfluoromethyl 2-perfluoroethyl methyl methacrylate, 2-perfluorohexyl ethyl methacrylate, methacrylate Acid 2-perfluorodecyl ethyl, methacrylic acid fluorinated alkyl esters such as methacrylic acid 2-perfluoroalkyl-hexadecyl ethyl. Among these, methyl methacrylate is preferable. These may be used alone or in combination of two or more.

  The methacrylic polymer block (A) contains a methacrylic acid ester as a main component, but may contain 50 to 0% by weight of a vinyl monomer copolymerizable therewith. Examples of the copolymerizable vinyl monomer include acrylic acid esters, aromatic alkenyl compounds, vinyl cyanide compounds, conjugated diene compounds, halogen-containing unsaturated compounds, silicon-containing unsaturated compounds, vinyl ester compounds, and maleimides. Compound etc. can be mentioned.

  Examples of the acrylate ester include methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-pentyl acrylate, n-hexyl acrylate, Acrylic aliphatic hydrocarbons such as n-heptyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, dodecyl acrylate, stearyl acrylate, etc. (eg, alkyl having 1 to 18 carbon atoms) ) Esters; Acrylic alicyclic hydrocarbon esters such as cyclohexyl acrylate and isobornyl acrylate; Aromatic aromatic hydrocarbon esters such as phenyl acrylate and toluyl acrylate; Aralkyl acrylates such as benzyl acrylate; Esters of acrylic acid and functional group-containing alcohol having etheric oxygen such as 2-methoxyethyl acrylate and 3-methoxybutyl acrylate; trifluoromethyl methyl acrylate, 2-trifluoromethyl ethyl acrylate, acrylic acid 2-perfluoroethylethyl, 2-perfluoroethyl-2-perfluorobutylethyl acrylate, 2-perfluoroethyl acrylate, perfluoromethyl acrylate, diperfluoromethyl methyl acrylate, 2-perfluoro acrylate Examples thereof include fluorinated alkyl acrylates such as methyl-2-perfluoroethylmethyl, 2-perfluorohexylethyl acrylate, 2-perfluorodecylethyl acrylate, and 2-perfluorohexadecylethyl acrylate. .

  Examples of the aromatic alkenyl compound include styrene, α-methylstyrene, p-methylstyrene, p-methoxystyrene, and the like.

  Examples of the vinyl cyanide compound include acrylonitrile and methacrylonitrile.

  Examples of the conjugated diene compound include butadiene and isoprene.

  Examples of the halogen-containing unsaturated compound include vinyl chloride, vinylidene chloride, perfluoroethylene, perfluoropropylene, and vinylidene fluoride.

  Examples of the vinyl ester compound include vinyl acetate, vinyl propionate, vinyl pivalate, vinyl benzoate, vinyl cinnamate, and the like.

  Examples of the maleimide compound include maleimide, methylmaleimide, ethylmaleimide, propylmaleimide, butylmaleimide, hexylmaleimide, octylmaleimide, dodecylmaleimide, stearylmaleimide, phenylmaleimide, cyclohexylmaleimide and the like.

<(Meth) acrylic polymer block (B)>
The (meth) acrylic polymer block (B) is a block formed by polymerizing a monomer mainly composed of methacrylic acid ester and / or acrylic acid ester. The main component means that 50% by weight or more of the monomers constituting the (meth) acrylic polymer block (B) is methacrylic acid ester and / or acrylic acid ester. If it is less than 50% by weight, the thermal decomposability tends to decrease. The content ratio of methacrylic acid ester / acrylic acid ester is not particularly limited, but can be set to 100/0 to 50/50 when it is desired to improve thermal decomposability, and when it is desired to improve thixotropy. 49/51 to 0/100.

  As the methacrylic acid ester, those similar to the methacrylic acid ester used in the methacrylic polymer block (A) can be used. However, since the glass transition temperature is low, n-butyl methacrylate, 2-methacrylic acid 2- Ethylhexyl and decyl methacrylate are preferable, and n-butyl methacrylate is more preferable from the viewpoint of cost. These may be used alone or in combination of two or more.

  As an acrylic ester, the thing similar to the acrylic ester used for the said methacrylic polymer block (A) can be used. Among these, butyl acrylate, ethyl acrylate, and 2-methoxyethyl acrylate are preferable. These may be used alone or in combination of two or more.

  The acrylic polymer block (B) contains (meth) acrylic acid ester as a main component, but may contain 50 to 0% by weight of a vinyl monomer copolymerizable therewith. Examples of different types of copolymerizable vinyl monomers include the above-mentioned aromatic alkenyl compounds, vinyl cyanide compounds, conjugated diene compounds, halogen-containing unsaturated compounds, silicon-containing unsaturated compounds, vinyl ester compounds, and maleimides. Compound etc. can be mentioned.

<Functional group (C)>
The acrylic block copolymer constituting the binder resin of the present invention has at least one functional group (C) selected from the group consisting of a carboxyl group, an acid anhydride group, a hydroxyl group, and an epoxy group. . Of these, a carboxyl group and a hydroxyl group are preferred from the viewpoint of dispersibility of the inorganic particles.

  The functional group (C) may be present in any of the methacrylic polymer block (A) and the (meth) acrylic polymer block (B), and is selected according to the characteristics required as a binder resin. However, in order to avoid an increase in the viscosity of the paste composition, it is preferable to have it in the (meth) acrylic polymer block (B).

  The content of these functional groups (C) can be appropriately selected from the dispersibility, viscosity, thixotropy, and thermal decomposability required as a binder resin, but the thermal decomposability decreases as the content increases. Or the interaction between polymer chains may increase with time, and the viscosity stability over time may be reduced. Therefore, the content is preferably 5% by weight or less in the acrylic block copolymer. % Or less is more preferable.

  The method for introducing the functional group (C) into the acrylic block copolymer is not particularly limited, and a method of copolymerizing a monomer having a functional group (C), a function that serves as a precursor of the functional group (C). There is a method in which a functional group (C) is generated by a known chemical reaction after copolymerizing a monomer having a group.

  Examples of the monomer having a carboxyl group include unsaturated carboxylic acid compounds such as (meth) acrylic acid, unsaturated dicarboxylic acid compounds such as maleic acid and fumaric acid, and monoester compounds thereof. Moreover, a carboxyl group can be converted from a functional group serving as a precursor thereof. Examples of the monomer having a functional group serving as a precursor of a carboxyl group include t-butyl (meth) acrylate, trimethylsilyl (meth) acrylate, isopropyl (meth) acrylate, and (meth) acrylic acid α, α. -Dimethylbenzyl, (meth) acrylic acid α-methylbenzyl and the like. After these monomers are polymerized, a carboxyl group can be generated by hydrolysis, acid decomposition, thermal decomposition or the like.

  Examples of the monomer having an acid anhydride group include maleic anhydride. Moreover, as a functional group used as the precursor of an acid anhydride group, a carboxyl group is mentioned, As a method of introduce | transducing a carboxyl group, the said method can be mentioned.

  Examples of the monomer having a hydroxyl group include (meth) acrylic acid-2-hydroxyethyl, (meth) acrylic acid-2-hydroxypropyl, (meth) acrylic acid-3-hydroxypropyl, and (meth) acrylic acid. -4-hydroxybutyl, glycerin mono (meth) acrylate, Blemmer PE series (Nippon Yushi Co., Ltd.), Blemmer AE series (Nippon Yushi Co., Ltd.), Blemmer P (Nippon Yushi Co., Ltd.), Blemmer PP series (Japan) Oil & Fat Co., Ltd., Blemmer AP Series (Nippon Yushi Co., Ltd.), Blemmer PEP Series (Nippon Yushi Co., Ltd.), Blemmer AEP Series (Nippon Yushi Co., Ltd.), Blemmer PET Series (Nippon Yushi Co., Ltd.), Blemmer AET series (Nippon Yushi Co., Ltd.), Blemmer PPT series (Nippon Yushi) Co., Ltd.)), Brenmer APT series (Nippon Oil & Fats Co., Ltd.), and the like.

  Examples of the monomer having an epoxy group include glycidyl (meth) acrylate, 2,3-epoxy-2-methylpropyl (meth) acrylate, (3,4-epoxycyclohexyl) methyl (meth) acrylate, and the like ( Examples thereof include esters of (meth) acrylic acid with an organic group-containing alcohol containing an epoxy ring, and epoxy group-containing unsaturated compounds such as 4-vinyl-1-cyclohexene 1 and 2 epoxides.

<Production method of acrylic block copolymer>
As a method for producing the acrylic block copolymer, it is preferable to use a controlled polymerization method. Controlled polymerization methods include living anion polymerization (JP-A-11-335432), polymerization using an organic rare earth transition metal complex as a polymerization initiator (JP-A-6-93060), radical polymerization using a chain transfer agent (special Kaihei 2-45511), controlled radical polymerization, and the like. In the present invention, controlled radical polymerization is particularly preferable from the viewpoint of easy polymerization of a monomer having a functional group.

  Examples of the controlled radical polymerization method include a polymerization method using a chain transfer agent such as polysulfide, a polymerization method using a cobalt porphyrin complex, a polymerization method using a nitroxide (WO 2004/014926), and a high-cycle heteroelement compound such as an organic tellurium compound. And the like. (Polymer No. 3839829), Reversible Addition / Desorption Chain Transfer Polymerization (RAFT) (Patent No. 3639859), Atom Transfer Radical Polymerization (ATRP) (Patent No. 3040172), and the like.

  In the present invention, the atom transfer radical polymerization method is preferable in that an acrylic block copolymer controlled with inexpensive raw materials and mild reaction conditions can be obtained. The central metal of the catalyst used for atom transfer radical polymerization is preferably copper from the viewpoint of polymerization control and cost. As a method for producing the acrylic block copolymer (A) using the atom transfer radical polymerization method, for example, the method described in WO2004 / 013192 can be used.

<Binder resin>
In the binder resin of the present invention, a decomposition accelerator, a decomposition retarder, a gas generating agent, a filler, a liquid resin, a coupling agent, an organic solvent, etc., which are generally used as a binder resin composition can be used as necessary. .

  Examples of the decomposition accelerator include azo compounds; heavy metal compounds such as iron sulfate, sodium nitrate, and cobalt naphthenate; carboxylic acids such as oxalic acid, linolenic acid, and ascorbic acid; hydroquinone, peroxide, tin oxide, and the like. . Among these, peroxides are preferred because the decomposition residue due to the decomposition accelerator can be kept low. Moreover, since the decomposition promotion effect by the decomposition accelerator and the nitrogen gas generated by the decomposition can be promoted by the decomposition accelerator, an azo compound is also preferable.

  Examples of the decomposition retarder include mercapto compounds, amine compounds, organic tin, and organic boron.

  Examples of the gas generating agent include azo compounds and azide compounds.

  Examples of the filler include titanium oxide, alumina, colloidal calcium carbonate, heavy calcium carbonate, barium carbonate, magnesium carbonate, silica, surface-treated silica, calcium silicate, anhydrous silicon, hydrous silicon, mica, surface-treated mica, talc, and clay. , Surface treatment talc, boron nitride, alumina nitride, carbon nitride, carbon black, white carbon, short glass fiber, glass beads, glass balloon, shirasu balloon, acrylic beads, polyethylene beads and the like. However, since the filler becomes an inorganic residue, its content should be kept to the minimum necessary.

  Specific examples of the liquid resin include polypropylene glycol, polyester polyol oligomer, butyl acrylate oligomer, 2-ethylhexyl acrylate oligomer, polyisoprene oligomer, polybutadiene oligomer, lauryl methacrylate oligomer, polyethylene glycol oligomer, polypropylene oligomer, polytetramethylene glycol oligomer. , Dioctyl phthalate, dibutyl phthalate, glycerin monooleate and the like.

  As coupling agents, silane coupling agents such as vinyltrimethoxysilane, dimethyldimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, tetramethoxysilane; isopropyl triisostearoyl titanate, isopropyl-n-dodecylbenzenesulfonyl titanate, etc. And titanium coupling agents.

  As the organic solvent, those having a boiling point of 150 ° C. or higher are preferable from the viewpoint of stability of solid content and viscosity stability at the time of printing, for example, terpineol, ethylene glycol ethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoethyl. Examples include ether acetate, butyl carbitol, butyl carbitol acetate, isophorone, butyl lactate, dioctyl phthalate, dioctyl adipate, benzyl alcohol, phenylpropylene glycol, and cresol. Especially, the solvent which does not contain an aromatic ring in which an organic residue does not remain easily is preferable.

<Paste composition>
The paste composition using the binder resin of the present invention comprises a binder resin and inorganic particles. Examples of the inorganic particles include conductive particles such as metals and metal oxides, and dielectric particles such as ceramics and glass. Examples of the metal particles include copper, silver, gold, platinum, nickel, aluminum, tungsten, molybdenum, and palladium. Examples of the metal oxide particles include silver oxide, alumina, titanium oxide, zirconium oxide, indium oxide, indium tin oxide, magnesium oxide, and zinc oxide. As the ceramic particles, for example, conventionally used metal oxide powders, non-metal oxides or non-oxide powders can be used. Specific examples include BaTiO ₃ , Al ₂ O ₃ , ZnO, LaCrO ₃ , iron group oxide, vanadium group oxide, ZnO—Bi ₂ O ₃ , SnO ₂ , ZrO ₂ , LaB ₆ , Zn—Mn ferrite, SrO · 6Fe ₂ O ₃ , In ₂ O ₃ , CaWO ₄ , LaF ₄ , Y ₂ O ₂ S, ZnS, Y ₃ Al ₅ O ₁₂ , GaAs, Bi ₄ (GeO ₄ ) ₃ , LiNbO ₃ , BaNaNb ₅ O ₁₅ , ThO ₂ , K ₂ O.nTiO ₂ .nSiO ₂ , BeO, WC, TiC, B ₄ C, SiC, Si ₃ N ₄ , Ca ₅ (F, Cl) P ₃ O ₁₂ , TiO ₂ , K ₂ O.nAl ₂ O ₃ , PZT, YIG and the like can be mentioned. Examples of the glass particles include lead borosilicate glass, lead glass, CaO.Al ₂ O ₃ .SiO ₂ inorganic glass, MgO.Al ₂ O ₃ .SiO ₂ inorganic glass, Li ₂ O.Al ₂ O _3. Examples thereof include low-melting glass such as SiO ₂ inorganic glass.

  When conductive particles such as metal are used in the paste composition of the present invention, a conductor such as a wiring conductor can be formed by firing. When dielectric particles such as ceramic particles are used, the dielectric can be formed by firing.

  EXAMPLES Although this invention is demonstrated further in detail based on an Example, this invention is not limited only to these Examples. In the examples, BA, MMA, TBA, and EA respectively represent n-butyl acrylate, methyl methacrylate, t-butyl acrylate, and ethyl acrylate.

<Molecular weight measurement method>
The molecular weight shown in this example was measured by the GPC analyzer shown below, and the molecular weight in terms of polystyrene was determined using chloroform as the mobile phase. As a system, a GPC system manufactured by Waters was used, and Shodex K-804 (polystyrene gel) manufactured by Showa Denko Co., Ltd. was used for the column.

<Method for measuring conversion rate of polymerization reaction>
The conversion rate of the polymerization reaction shown in this example was measured using the following analyzer and conditions.
Equipment used: Gas chromatography GC-14B manufactured by Shimadzu Corporation
Separation column: J & W SCIENTIFIC INC, capillary column DB-17, 0.35 mmφ × 30 m
Separation conditions: Initial temperature 50 ° C., hold for 3.5 minutes
Temperature increase rate 40 ° C / min
Final temperature 140 ° C, hold for 1.5 minutes
Injection temperature 250 ° C
Detector temperature 250 ° C
Sample preparation: The sample was diluted about 10 times with ethyl acetate, and acetonitrile was used as an internal standard substance.

<Thermal degradation evaluation method>
The thermal decomposability of the acrylic block copolymer was measured by a differential thermothermal gravimetric simultaneous measurement apparatus (DTG-50) manufactured by Shimadzu Corporation (SHIMADZU), and evaluated by weight loss when the temperature was raised to 500 ° C. The measurement was performed under the condition of a heating rate of 10.0 ° C./min under a nitrogen stream at a flow rate of 50.0 ml / min. The weight loss was based on the weight at room temperature.

<Thix index measurement method>
The thixo index in the solution state of the acrylic block copolymer is the viscosity of 2 and 20 rpm at 25 ° C. of the acrylic block copolymer dissolved in toluene at 40 wt% using a Brookfield B-type viscometer. It was calculated from the ratio.

Example 1
A 500-liter pressure-resistant reactor purged with nitrogen was charged with 78 kg of butyl acrylate, 2.9 kg of tert-butyl acrylate, 690 g of copper bromide, 7.1 kg of acetonitrile, and 1.3 kg of diethyl 2,5-dibromoadipate while stirring. Warmed to 75 ° C. Thereafter, 83 g of pentamethyldiethylenetriamine was added to initiate polymerization. About 100 g of the polymerization solution was sampled from the polymerization solution for sampling at regular intervals from the start of polymerization, and the conversion rate of BA was determined by gas chromatogram analysis. The polymerization rate was controlled by adding pentamethyldiethylenetriamine as needed. When the conversion rate of BA reached 99%, 104 kg of toluene, 480 g of copper chloride, 48 kg of methyl methacrylate, 7.8 kg of ethyl acrylate, and 83 g of pentamethyldiethylenetriamine were added. When the conversion rate of MMA reached 95%, 290 kg of toluene was added to dilute the reaction solution, and the reactor was cooled to stop the polymerization.

  To this polymer solution, 2.2 kg of p-toluenesulfonic acid monohydrate was added and the mixture was heated and stirred at 150 ° C. for 4 hours to convert the t-butyl ester group in TBA into a carboxyl group. After cooling to room temperature, 2.7 kg of Radiolite # 3000 manufactured by Showa Chemical Industry was added. Thereafter, pressure filtration was performed at 0.1 to 0.4 MPaG using a pressure filter equipped with polyester felt as a filter medium to separate a solid content.

  To the resulting acidic solution, 1.3 kg of Kyowa Kayodo 500SH as a solid base was added and stirred at 30 ° C. for 1 hour. Thereafter, the solid content was separated by pressure filtration at 0.1 to 0.4 MPaG using a pressure filter equipped with polyester felt as a filter medium. The obtained polymer solution was vacuum-dried to remove the solvent and unreacted monomers to obtain the target acrylic block copolymer 1.

  When the GPC analysis of the obtained acrylic block copolymer 1 was conducted, the number average molecular weight (Mn) was 52,900 and the molecular weight distribution (Mw / Mn) was 1.47. The weight ratio of the methacrylic polymer block to the (meth) acrylic polymer block was 60/40. The carboxyl group content was 0.75% by weight. The glass transition temperature of the methacrylic polymer block was 78 ° C, and the glass transition temperature of the acrylic polymer block was -52 ° C.

  The acrylic block copolymer 1 had a weight loss of 96.1% at 500 ° C. and a thixo index of 5.0.

(Example 2)
Except for using 545 g of butyl acrylate, 46 g of 2-hydroxyethyl acrylate, 5.0 g of copper bromide, 51 g of acetonitrile, 7 g of diethyl 2,5-dibromoadipate, and 0.6 g of pentamethyldiethylenetriamine using a 5 L pressure-resistant reactor. Was started in the same manner as in Example 1, and then the same as in Example 1 except that 775 g of toluene, 3.5 g of copper chloride, 360 g of methyl methacrylate, 58 g of ethyl acrylate, and 0.6 g of pentamethyldiethylenetriamine were used. And polymerized. The polymerization was stopped by adding 2000 g of toluene, and the mixture was stirred at 30 ° C. for 3 hours using 16 g of p-toluenesulfonic acid monohydrate. 19 g of Radiolite # 3000 was added, and the solid content was separated by pressure filtration at 0.1 to 0.4 MPaG using a pressure filter equipped with a polyester felt as a filter medium. To the obtained acidic solution, 15 g of KYOWARD 500SH was added, and the solid content was separated by pressure filtration at 0.1 to 0.4 MPaG using a pressure filter equipped with polyester felt as a filter medium. An acrylic block copolymer 2 was obtained.

  When the GPC analysis of the obtained acrylic block copolymer 2 was conducted, the number average molecular weight (Mn) was 85,000, and molecular weight distribution (Mw / Mn) was 1.53. The weight ratio of the methacrylic polymer block to the (meth) acrylic polymer block was 60/40. The hydroxyl group content was 1.1% by weight. The glass transition temperature of the methacrylic polymer block was 78 ° C., and the glass transition temperature of the acrylic polymer block was −51 ° C.

(Comparative Example 1)
A 5 L pressure-resistant reactor was used, except that 707 g of butyl acrylate, 26 g of t-butyl acrylate, 3.2 g of copper bromide, 64 g of acetonitrile, 20 g of diethyl 2,5-dibromoadipate, and 0.4 g of pentamethyldiethylenetriamine were used. The polymerization was started in the same manner as in Example 1, and then the same as in Example 1 except that 723 g of toluene, 3.3 g of copper chloride, 447 g of methyl methacrylate, 72 g of ethyl acrylate, and 0.4 g of pentamethyldiethylenetriamine were used. Polymerized. 1000 g of toluene was added to terminate the polymerization, and conversion to a carboxyl group was carried out in the same manner as in Example 1 using 15 g of p-toluenesulfonic acid monohydrate. Thereafter, the target acrylic block copolymer 3 was obtained in the same manner as in Example 1 using 24 g of Radiolite # 3000 and 48 g of Kyoward 500SH.

  When the GPC analysis of the obtained acrylic block copolymer 3 was conducted, the number average molecular weight (Mn) was 29,400 and the molecular weight distribution (Mw / Mn) was 1.34. The weight ratio of the methacrylic polymer block to the (meth) acrylic polymer block was 60/40. The carboxyl group content was 0.81% by weight. The glass transition temperature of the methacrylic polymer block was 78 ° C, and the glass transition temperature of the acrylic polymer block was -52 ° C.

  The weight loss of this acrylic block copolymer 1 at 500 ° C. was 98.1%, and the thixo index was 1.0.

Claims (11)

An acrylic block copolymer comprising 10 to 90% by weight of a methacrylic polymer block (A) and 90 to 10% by weight of a (meth) acrylic polymer block (B), wherein the methacrylic polymer block (A ) Is higher than the glass transition temperature of the (meth) acrylic polymer block (B), the number average molecular weight is 10,000 to 100,000, the molecular weight distribution is 1.8 or less, A binder resin having a thixotropy (viscosity at 2 rpm (25 ° C.) / Viscosity at 20 rpm (25 ° C.)) of 1.5 to 5.5 when 40% by weight is dissolved. 2. The weight loss when the acrylic block copolymer is heated to 500 ° C. in a nitrogen atmosphere at a heating rate of 10.0 ° C./min is 95% or more. Binder resin. The acrylic block copolymer is selected from the group consisting of at least one of a methacrylic polymer block (A) and a (meth) acrylic polymer block (B), a carboxyl group, an acid anhydride group, a hydroxyl group, and an epoxy group. The binder resin according to claim 1, wherein the binder resin has at least one selected functional group (C). The binder resin according to claim 3, wherein the functional group (C) is a carboxyl group or a hydroxyl group. The binder resin according to any one of claims 1 to 4, wherein the content of the functional group (C) is 5% by weight or less in the acrylic block copolymer. The binder resin according to any one of claims 1 to 5, wherein the acrylic block copolymer is produced by controlled radical polymerization. The binder resin according to any one of claims 1 to 6, wherein the acrylic block copolymer is produced by atom transfer radical polymerization. A paste composition comprising the binder resin according to claim 1 and inorganic particles. The paste composition according to claim 8, wherein the inorganic particles are conductive particles. The paste composition according to claim 8 or 9, wherein the inorganic particles are metal particles. The paste composition according to claim 8, wherein the inorganic particles are ceramic particles.