JP2013082902A - Resin composition for paste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition for paste for maintaining a low viscosity even in a high nonvolatile concentration, and generating an excellent thixotropic property while having firing property with less fired residue.SOLUTION: The resin composition for paste comprises: an organic solvent; and a non-water-dispersed resin dispersed in the organic solvent containing a polymer structure part A for gathering organic solvent insoluble polymers, and an organic solvent soluble polymer B whose at least one part is bonded or adsorbed to the polymer structure part A.

Description

  The present invention relates to a resin composition for paste in which a resin component is dispersed in an organic solvent.

  Inorganic pastes prepared by mixing inorganic materials such as inorganic fine particles such as glass powder and conductive powder and organic materials (binder resin dissolved in organic solvent) are used to obtain fired bodies of various shapes. Widely used in

  In producing a fired body using an inorganic paste, it is processed into a predetermined shape by screen printing, a coating method using a doctor blade, a casting method for processing into a sheet shape, etc., and then dried and fired. Thus, a desired fired body can be obtained. Among these, the method by screen printing is a method particularly suitable for mass production, and is applied to the formation of various electronic parts and the like.

  For example, the partition (rib) provided on the back glass substrate of a PDP (plasma display) can be formed using an inorganic paste. As a specific example, a glass paste in which glass powder, white inorganic powder, and organic material are mixed to adjust the thixotropy index and shear rate to a predetermined range is printed on a glass substrate by screen printing, dried, and fired. It is disclosed that a partition is formed by this (for example, refer patent document 1).

  The inorganic paste is also used for forming a light receiving surface electrode of a solar cell, for example. For example, a technique is disclosed in which a paste composition for a solar cell electrode in which silver powder, glass powder, and a vehicle containing predetermined ethyl cellulose are mixed is applied by screen printing, dried and fired to form an electrode. (For example, refer to Patent Document 2).

  As described above, the screen printing method is widely used as a method for applying the inorganic paste. However, in this method, the coating thickness at one time generally remains on the order of several tens of μm. Therefore, in order to increase the height of the partition walls such as PDP, for example, it is necessary to repeatedly perform printing and subsequent drying many times, and the productivity is extremely poor. Therefore, there is a problem that it is difficult to obtain a good shape. In addition, in the composition using ethyl cellulose, residual charcoal is likely to be generated even when fired, and the fireability is poor.

As characteristics required for inorganic pastes, particularly pastes used for screen printing, printability, shape retention, and firing are particularly important. That is,
As for printability, in order to perform screen printing satisfactorily, inorganic paste has a low viscosity during coating and is easy to print. On the other hand, when separating the plate or when standing and drying after printing, the viscosity is low. Therefore, so-called thixotropy is required to be high and not fluent.
The inorganic paste is required to have a high non-volatile content (solid content) and a low viscosity. Thereby, shape retention property is expressed. If the paste has a low non-volatile content, the shrinkage during firing is large, so it is necessary to print with a certain thickness. Further, if the paste is simply made to have a high non-volatile content, the viscosity becomes too high and the printability deteriorates.
Furthermore, the inorganic paste is required to have a property (baking property) that the binder has good thermal decomposability at low temperatures and no residue remains after baking. In a composition with poor flammability, an organic component (carbon) remains as an impurity, and it is necessary to heat at a higher temperature.

  In view of the above situation, various studies have been made in the past. For example, by containing gel fine particles made of a crosslinked (meth) acrylic resin, inorganic fine particles, and an organic solvent, the thixotropy is excellent, and thus screen printability. An inorganic fine particle-dispersed paste composition (see, for example, Patent Document 3) that can be fired at a low temperature is disclosed. In addition, an inorganic fine particle dispersed paste containing a predetermined (meth) acrylic resin or an organic solvent and excellent in screen printability (for example, see Patent Document 4), or a calcination type paste that can impart high viscosity in a small amount and has excellent calcination properties. An acrylic binder resin composition for use (see, for example, Patent Document 5) is disclosed.

  In addition, as a composition for a coating vehicle, a non-aqueous resin containing an organic solvent mainly composed of an aliphatic hydrocarbon solvent, a copolymer soluble in the organic solvent, fine particles insoluble in the organic solvent, etc. A composition is disclosed (for example, see Patent Document 6), and it is said that the weather resistance, solvent resistance and adhesion of the coating film are remarkably improved.

JP 2000-327371 A JP 2009-246277 A JP 2008-63457 A JP 2009-227731 A JP 2002-80675 A JP 2000-95917 A

  As described above, although various studies have been made on the method of forming partition walls (ribs) for PDP, electrodes for solar cells, and the like by screen printing, they have printability and shape retention. However, a technique for sufficiently achieving the thickness, height, and fineness required for structures such as partition walls and electrodes has not yet been established.

Among the above conventional techniques, in the inorganic fine particle dispersed paste composition using gel fine particles made of a cross-linked (meth) acrylic resin, the thixotropic property is obtained, but the resin has a cross-linked structure. Is likely to occur. On the other hand, as in Patent Documents 4 to 5, the composition using the (meth) acrylic resin as the resin component is expected to improve the sinterability, but the viscosity increases when the non-volatile content is high, and the thixotropic property is increased. There is a tendency to be inferior.
In addition, the conventional non-aqueous resin composition containing fine particles such as a copolymer soluble in an organic solvent and a polymer insoluble in the organic solvent in the organic solvent is a paste used for coating and used for screen printing. The suitability as is not considered.

  As described above, it has thixotropic properties advantageous for printability and shape retention while having a high non-volatile content that suppresses heat shrinkage and obtains a desired shape, and can be fired at low temperature and has no concern about residues. In fact, the paste material having the above has not been proposed yet, and the provision of such a paste material is demanded.

  The present invention has been made in view of the above, and provides a resin composition for paste that has a low non-volatile content while maintaining a high non-volatile content, exhibits excellent thixotropic properties, and has low baking residue and baking properties. It is an object to achieve this purpose.

Specific means for achieving the above object are as follows.
<1> An organic solvent, a polymer structure portion A in which insoluble polymers insoluble in an organic solvent are aggregated, and an organic solvent-soluble soluble polymer B at least partially bonded or adsorbed to the polymer structure portion A, A paste resin composition comprising a non-aqueous dispersion resin dispersed therein.

<2> The organic solvent has a solubility parameter (SP value) of 8.0 (cal / cm ³ ) ^0.5 or more and 10.0 (cal / cm ³ ) ^0.5 or less and a boiling point of 180 ° C. or more. It is a resin composition for pastes as described in said <1> which is 280 degrees C or less.

  <3> At least one of the insoluble polymer of the polymer structure portion A and the soluble polymer B is the resin composition for paste according to <1> or <2>, which is a (meth) acrylic resin.

  <4> The paste resin composition according to any one of <1> to <3>, wherein the organic solvent is at least one of butyl carbitol acetate, terpineol, and texanol.

<5> The SP value (SPA) of the insoluble polymer of the polymer structure portion A is larger than the SP value (SPB) of the soluble polymer B, and the SPA and the SPB satisfy the following formula 1: <1> to <4>. The paste resin composition according to any one of 4>.
SPA-SPB <1.5 (Formula 1)

  <6> In the organic solvent, the ratio (A / B; mass ratio) of the polymer structure portion A to the soluble polymer B is 0.5 / 1 or more and 5/1 or less. It is the resin composition for pastes as described in any one of <5>.

  According to the present invention, there is provided a resin composition for paste having a low non-volatile content while maintaining a low viscosity, exhibiting excellent thixotropy and having low baking residue and baking properties.

Hereinafter, the resin composition for paste of the present invention will be described in detail.
The resin composition for paste of the present invention comprises an organic solvent and a polymer structure part A in which insoluble polymers insoluble in the organic solvent are aggregated, and an organic solvent-soluble soluble polymer in which at least a part is bonded or adsorbed to the polymer structure part A B and a non-aqueous dispersion resin dispersed in an organic solvent. This paste resin composition can be constituted by using other components such as a polymerization initiator and other additives as required.

Although the inorganic paste used for screen printing has been studied in the past, when the structure is formed by screen printing, the heat during firing that can achieve the desired thickness and height in one printing operation A composition that exhibits good thixotropy while having a high non-volatile content with little shrinkage, and has been provided with a composition that suppresses the generation of residues (particularly residual charcoal) after firing,
In the present invention, as the resin dispersed and contained in the organic solvent, a resin in which the organic solvent-soluble soluble polymer B is bonded or adsorbed to the polymer structure portion A in which insoluble polymers insoluble in the organic solvent are aggregated is used. The composition dispersed and contained in the solvent can maintain a low viscosity while maintaining a high non-volatile content that hardly undergoes heat shrinkage upon firing, and is excellent in thixotropic properties and is suitable for screen printing.

  In the present invention, thixotropy is a property in which when external stress such as shearing force is applied, the bond is broken and the viscosity is lowered, the fluidity is developed, and when stationary, the fluidity is lowered and the viscosity is restored again. Say.

Hereinafter, each component which comprises the resin composition for pastes of this invention is explained in full detail.
(Organic solvent)
The resin composition for paste of the present invention contains at least one organic solvent. The organic solvent is selected in consideration of the degree of hydrophilicity / hydrophobicity of the resin component dispersed therein, thixotropy when the resin component is dispersedly contained, volatility, and the like.

Specific examples of the organic solvent include, for example, methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, i-butyl alcohol, n-hexyl alcohol, n-octyl alcohol, i-octyl alcohol. Alcohol organic solvents such as 2-ethylhexyl alcohol, 2- (4-methylcyclohex-3-enyl) propan-2-ol (terpineol (also known as terpineol));
Methyl carbitol, ethyl carbitol, n-propyl carbitol, i-propyl carbitol, n-butyl carbitol, i-butyl carbitol, i-amyl carbitol, phenyl carbitol, benzyl carbitol diethyl carbitol, butyl Carbitol organic solvents such as carbitol acetate (BCA) and carbitol acetate;
Ester organic solvents such as propylene carbonate, 2-ethylhexyl acetate, 2-ethylhexanoic acid-ethylhexyl;
Ketone organic solvents such as acetone, methyl ethyl ketone, methyl-i-butyl ketone, methyl amyl ketone, cyclohexanone, diacetone alcohol;
Hydrocarbon organic solvents such as isoparaffin;
And so on.

The solubility parameter of the organic solvent (hereinafter abbreviated as “SP value”) is determined based on the relationship with the SP value of the non-aqueous dispersion resin described later, but preferably 8.0 (cal / cm ³ ) ^{0. 5} or more and 10.0 (cal / cm ³ ) ^0.5 or less. When the SP value is within the above range, the viscosity when prepared to have a high nonvolatile content is kept low, and the thixotropic property is excellent. Among these, the SP value of the organic solvent is more preferably in the range of 8.5 (cal / cm ³ ) ^0.5 or more and 9.5 (cal / cm ³ ) ^0.5 or less for the same reason as described above.

The SP value (solubility parameter / unit: (cal / cm ³ ) ^0.5 ) in the present invention is a value represented by the square root of the molecular cohesive energy, and is calculated by the Hildebrand method.

Moreover, as an organic solvent, the organic solvent whose boiling point exists in the range of 180 to 280 degreeC is preferable. When the boiling point is 180 ° C. or higher, it is suitable for screen printing, and the coating workability during coating when used for screen printing is reduced. Moreover, it is advantageous at the leveling property that a boiling point is 280 degrees C or less.
Among these, for the same reason as described above, the boiling point is more preferably 200 ° C. or higher and 260 ° C. or lower.

  Among the organic solvents described above, the organic solvent in the present invention is preferably an alcohol organic solvent or a carbitol organic solvent from the viewpoint that it has a relatively high boiling point and does not easily volatilize in the atmosphere and can easily maintain thixotropic properties. Furthermore, terpineol, butyl carbitol acetate (BCA), and texanol are more preferable in that better thixotropy can be obtained. Among these, butyl carbitol acetate having a boiling point of 247 ° C. is particularly preferable.

  As content of the organic solvent in the resin composition for pastes of this invention, 30-60 mass% is preferable with respect to the quantity of the non-aqueous dispersion resin mentioned later, and 40-50 mass% is more preferable. When the content of the organic solvent is within the above range, a composition having a high nonvolatile content and a thixotropic property can be easily obtained, and a structure having a good height and shape can be formed when screen printing is performed.

(Non-aqueous dispersion resin)
The resin composition for paste according to the present invention is configured as a non-aqueous dispersion (non-aqueous dispersion) in which at least one non-aqueous dispersion resin is dispersed and contained in the organic solvent. The non-aqueous dispersion resin has at least a polymer structure portion A in which insoluble polymers insoluble in an organic solvent are assembled, and an organic solvent-soluble soluble polymer B in which at least a portion is bonded or adsorbed to the polymer structure portion A. The polymer structure portion A is a polymer component that is not dissolved in the organic solvent and the soluble polymer B is dispersed in a state dissolved in the organic solvent.

~ Polymer structure part A ~
The polymer structure portion A constituting the non-aqueous dispersion resin in the present invention forms a particle nucleus formed by a collection of insoluble polymers insoluble in organic solvents.

  The insoluble polymer insoluble in the organic solvent may be either a homopolymer of one kind of monomer (monomer) or a copolymer of two or more kinds of monomers (monomers), but it controls the solubility in an organic solvent. In view of the above, a copolymer of two or more monomers is preferable.

  The monomer that forms the insoluble polymer can be appropriately selected from (meth) acrylic monomers, styrene monomers, vinyl monomers, nitrile monomers, and the like. The monomer forming the insoluble polymer is selected in terms of the type and the proportion of the polymer in consideration of solubility in an organic solvent, viscosity of the composition, thixotropy, and calcinability. In the present invention, a (meth) acrylic monomer is particularly preferable from the viewpoint of bakability after screen printing.

Examples of monomers that form insoluble polymers include methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, n-hexyl acrylate, n-octyl acrylate, and i-octyl. Alkyl or aryl ester of acrylic acid (preferably, alkyl moiety (including cycloalkyl) = 1 to 18, such as acrylate, 2-ethylhexyl acrylate, i-nonyl acrylate, stearyl acrylate, cyclohexyl acrylate, benzyl acrylate, etc. Carbon number of aryl moiety = 6-8);
Methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, n-hexyl methacrylate, n-octyl methacrylate, i-octyl methacrylate, 2-ethylhexyl methacrylate, i-nonyl methacrylate, n-dodecyl methacrylate , I-dodecyl methacrylate, stearyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, etc., alkyl or aryl ester of methacrylic acid (preferably, carbon number of alkyl moiety (including cycloalkyl) = 1 to 18, carbon number of aryl moiety = 6-8);
Aromatic vinyl such as styrene, vinyl toluene, ethyl vinyl benzene;
And radical polymerizable unsaturated monomers.

Moreover, the following functional group monomer can be copolymerized with the radical polymerizable unsaturated monomer. That is, for example, a carboxyl group-containing monomer (preferably acrylic acid, methacrylic acid) such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, citraconic acid;
Amide group or substituted amide group-containing monomers such as acrylamide, methacrylamide, N, N-dimethylacrylamide, N-methylacrylamide, Nn-butoxymethylacrylamide (preferably acrylamide, methacrylamide);
Hydroxyl-containing monomers such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, allyl alcohol, methallyl alcohol (preferably 2-hydroxyethyl acrylate, 2-hydroxypropyl Hydroxy lower alkyl (meth) acrylates such as acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, etc. (preferably, lower alkyl having 1 to 4 carbon atoms);
Amino group or substituted amino group-containing monomer such as aminoethyl acrylate, N, N-dimethylaminoethyl acrylate, N, N-diethylaminoethyl acrylate, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate (Preferably, N, N-dilower alkylamino lower alkyl (meth) acrylate such as N, N-dimethylaminoethyl acrylate, N, N-diethylaminoethyl methacrylate, etc. Carbon number = 1 to 4]);
Epoxy group-containing monomers such as glycidyl methacrylate, glycidyl acrylate, glycidyl allyl ether, glycidyl methallyl ether, glycidyl vinyl ether;
Mercapto group-containing monomers such as vinyl mercaptan and allyl mercaptan;
(Poly) ethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, allyl (meth) acrylate, triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, divinylbenzene Monomers having two or more radically polymerizable unsaturated groups in one molecule; and the like.

  Among the above functional group monomers, a carboxyl group-containing monomer, an amide group-containing monomer, a hydroxyl group-containing monomer, and a substituted amino group-containing monomer are preferred, and (meth) acrylic acid, (meta ) Acrylamide, hydroxyalkyl (meth) acrylate having 1 to 4 carbon atoms in the alkyl moiety, and N, N-di-alkylaminoalkyl (meth) acrylate having 1 to 4 carbon atoms in the alkyl moiety.

Among them, the insoluble polymer is preferably a (meth) acrylic resin, a monomer selected from an alkyl or aryl ester of acrylic acid, and an alkyl or aryl ester of methacrylic acid, a carboxyl group-containing monomer, and an amide group-containing monomer. More preferably, it is formed by copolymerization with a monomer selected from a hydroxyl group-containing monomer and a substituted amino group-containing monomer.
More preferably, the insoluble polymer is an alkyl moiety (including cycloalkyl) having 1 to 18 carbon atoms (meth) acrylic acid alkyl ester, (meth) acrylic acid, (meth) acrylamide, or alkyl moiety having 1 to 1 carbon atoms. It is preferably formed by copolymerization with a monomer selected from 4 hydroxyalkyl (meth) acrylates and N, N-di-alkylaminoalkyl (meth) acrylates having 1 to 4 carbon atoms in the alkyl moiety.
As described above, by using the (meth) acrylic resin, the firing property when a structure (fired body) is obtained by firing after screen printing is improved, and the firing residue can be reduced.

The polymer structure part A is preferably a copolymer having a hydrophobic structural unit derived from a hydrophobic monomer and a hydrophilic structural unit derived from a hydrophilic monomer, and is insoluble in an organic solvent. The ratio of the hydrophilic structural unit (hydrophobic structural unit / hydrophilic structural unit [mass ratio]) is preferably in the range of 60/40 to 95/5.
Specifically, “alkyl ester (p) of methacrylic acid having 1 to 18 carbon atoms in alkyl moiety (including cycloalkyl)” and “hydroxyalkyl (meth) acrylate having 1 to 4 carbon atoms in alkyl moiety (q) ) ”And a ratio (p / q; mass ratio) of 60/40 to 95/5 is preferred.

  The average molecular weight of the polymer structure part A is preferably 10,000 to 300,000 in terms of weight average molecular weight, more preferably 100,000 to 200,000.

Solubility parameter (SP value, unit: (cal / cm ³ ) ^0.5 ) of the insoluble polymer of the polymer structure part A; hereinafter, it may be abbreviated as SPA. ) Is determined from the relationship between the SP value of the organic solvent and the SP value of soluble polymer B described below, and preferably 9.0 (cal / cm ³ ) ^0.5 or more and 10.0 (cal / Cm ³ ) ^0.5 or less.
The method for obtaining the SP value is as described above.

~ Soluble polymer B ~
The soluble polymer B constituting the non-aqueous dispersion resin in the present invention is soluble in an organic solvent, and at least a part thereof is bonded or adsorbed to the polymer structure part A, and at least a part thereof is dissolved in the organic solvent and is organic The dispersion stability in the solvent is maintained.

  The soluble polymer soluble in the organic solvent may be either a homopolymer of one kind of monomer (monomer) or a copolymer of two or more kinds of monomers (monomers), but it is bonded to the polymer structure part A. Alternatively, a copolymer of two or more kinds of monomers is preferable from the viewpoint of combining properties advantageous for adsorption and solubility in an organic solvent.

Examples of the monomer that forms the soluble polymer include the same monomers as those that form the insoluble polymer of the polymer structure portion A. The monomer that forms the soluble polymer B is selected in terms of the type and the ratio of the monomer to the polymer in consideration of solubility in an organic solvent, viscosity as a composition, thixotropy, and calcinability.
Examples of the monomer include radical polymerizable unsaturated monomers such as alkyl or aryl esters of acrylic acid, alkyl or aryl esters of methacrylic acid, and aromatic vinyl monomers, as well as carboxyl group-containing monomers and amide group-containing monomers. Preferred examples thereof include functional monomers such as a monomer, a hydroxyl group-containing monomer, and a substituted amino group-containing monomer. Details of these monomers are as described in the above-mentioned polymer structure portion A, and preferred embodiments thereof are also the same.

Among them, the soluble polymer B is preferably a (meth) acrylic resin, a monomer selected from an alkyl or aryl ester of acrylic acid and an alkyl or aryl ester of methacrylic acid, a carboxyl group-containing monomer, and an amide group-containing monomer. A polymer formed by copolymerization with a monomer selected from a monomer, a hydroxyl group-containing monomer, and a substituted amino group-containing monomer is more preferable.
More preferably, the soluble polymer is a C1-C18 (meth) acrylic acid alkyl ester having an alkyl moiety (including cycloalkyl), (meth) acrylic acid, (meth) acrylamide, and an alkyl moiety having one carbon atom. It is preferably formed by copolymerization with a monomer selected from hydroxyalkyl (meth) acrylate having ˜4 and N, N-di-alkylaminoalkyl (meth) acrylate having 1 to 4 carbon atoms in the alkyl moiety.
As described above, by using the (meth) acrylic resin, the calcination property is improved as described above, and the firing residue can be reduced.

For the soluble polymer B, a copolymer having a hydrophobic structural unit derived from a hydrophobic monomer and a hydrophilic structural unit derived from a hydrophilic monomer is preferably used, and the hydrophobic structural unit, the hydrophilic structural unit, The ratio (hydrophobic structural unit / hydrophilic structural unit [mass ratio]) is preferably in the range of 90/10 to less than 100/0, and more preferably in the range of 95/5 to 97/3.
Specifically, “alkyl ester (p) of methacrylic acid having 1 to 18 carbon atoms in alkyl moiety (including cycloalkyl)” and “hydroxyalkyl (meth) acrylate having 1 to 4 carbon atoms in alkyl moiety (q) ) ”, And a (meth) acrylic resin having a ratio (p / q; mass ratio) of 90/10 or more and less than 100/0 is preferable. A (meth) acrylic resin having a ratio (p / q; mass ratio) of 95/5 or more and 97/3 or less is more preferable.

  In the present invention, at least one of the insoluble polymer and the soluble polymer B of the polymer structure part A is preferably a (meth) acrylic resin in that it can be fired at a low temperature of 600 ° C. or less and the firing residue is reduced. More preferably, both the polymer and the soluble polymer are (meth) acrylic resins.

  In the present specification, (meth) acryl means both acrylic and methacrylic.

Solubility parameter of soluble polymer B (SP value, unit: (cal / cm ³ ) ^0.5 ); hereinafter may be abbreviated as SPB. ) Is determined from the relationship between the SP value of the organic solvent and the SP value of the insoluble polymer of the polymer structure portion A, and preferably 8.0 (cal / cm ³ ) ^0.5 or more and 9.5. (Cal / cm ³ ) ^0.5 or less.
The method for obtaining the SP value is as described above.

In addition, the SP value (SPA) of the insoluble polymer of the polymer structure portion A is preferably larger than the SP value (SPB) of the soluble polymer B. When the SPA is larger than SPB, it is advantageous in that a difference between the SPA and the SP value of the organic solvent is obtained to some extent, and the dispersion stability in the organic solvent is further improved. More preferably, SPA and SPB satisfy the following formula 1.
SPA-SPB <1.5 (Formula 1)
A difference obtained by subtracting SPB from SPA of less than 1.5 indicates that the values of SPA and SPB are relatively close. Therefore, the affinity between the insoluble polymer and the soluble polymer B in the polymer structure part A is increased, and the soluble polymer B is also in the polymer structure part even when a part of the soluble polymer B is dissolved in the organic solvent. Since the state firmly connected to A is maintained, stable dispersibility and thixotropy can be obtained, and a highly stable non-aqueous dispersion can be obtained.
Among these, the value of “SPA-SPB” is more preferably in the range of 0.5 to 1.0.

The ratio (A / B; mass ratio) of the polymer structure portion A to the soluble polymer B in the organic solvent is preferably in the range of 0.5 / 1 to 5/1. If the ratio A / B is 0.5 / 1 or more, it is advantageous in terms of leveling properties, and if it is 5/1 or less, it is advantageous in terms of dispersion stability.
The ratio A / B is more preferably in a range from 1/1 to 3/1. Better thixotropy can be ensured because the ratio of the polymer structure part A insoluble in the organic solvent to the soluble polymer B soluble in the organic solvent is large.

  The paste resin composition of the present invention contains a non-aqueous dispersion resin in which at least a part of the soluble polymer B is bonded or adsorbed to the polymer structure part A, but is bonded or adsorbed to the polymer structure part A. An embodiment in which the soluble polymer B not present is present in a floating state in an organic solvent is more preferred. The presence of such a soluble polymer B in an organic solvent improves the miscibility between the non-aqueous dispersion resin and the inorganic material, and improves the dispersibility of the inorganic material, thereby obtaining a paste having excellent leveling properties. .

The non-aqueous dispersion resin in the present invention is dispersed in an organic solvent to form a non-aqueous dispersion.
This non-aqueous dispersion resin may be obtained by previously forming a polymer soluble in an organic solvent in an organic solvent and polymerizing a monomer that forms a polymer insoluble in the organic solvent in the presence of this polymer. It is good, and a polymer part in which a polymer part soluble in an organic solvent and a polymer part insoluble in an organic solvent are blocked or grafted in advance is formed, and a polymer insoluble in an organic solvent is formed in the presence of this polymer. It may be a polymerized monomer.
Among these polymerization methods, a method in which a polymer soluble in an organic solvent is previously formed in an organic solvent, and a monomer that forms a polymer insoluble in the organic solvent in the presence of this polymer is simply not known. This is preferable from the viewpoint of obtaining a water-dispersed resin.
In the method of obtaining a non-aqueous dispersion resin by polymerizing a monomer that forms a polymer insoluble in an organic solvent in the presence of a polymer soluble in the organic solvent, the polymer soluble in the organic solvent is solution-polymerized in the organic solvent. Can be synthesized. This soluble polymer is charged with a monomer and, if necessary, a polymerization initiator and a chain transfer agent in the same organic solvent as that constituting the resin composition for paste, and stirred in a nitrogen stream or at the reflux temperature of the organic solvent. However, it can be suitably synthesized by heating reaction for several hours. At this time, at least a part of the organic solvent, monomer, polymerization initiator and / or chain transfer agent may be sequentially added. The polymerization temperature is generally preferably 30 to 180 ° C (preferably 60 to 150 ° C).
Subsequently, in an organic solvent in which a polymer soluble in the organic solvent is present, a monomer that gives a polymer portion that is insoluble in the organic solvent is mixed with a polymerization initiator and, if necessary, a chain transfer agent in a nitrogen stream or the reflux temperature of the organic solvent. By heating and polymerizing for several hours with stirring, an insoluble polymer insoluble in the organic solvent and a copolymer in which the insoluble polymer part is bonded to the soluble polymer part are formed. The formed polymer insoluble in the organic solvent forms a particle nucleus together with the insoluble polymer portion of the copolymer, and the polymer structure portion A in which insoluble polymers insoluble in the organic solvent are assembled, and at least a part of the polymer structure portion A Dispersed resin particles having a soluble polymer B bonded or adsorbed to can be obtained.

Examples of the polymerization initiator used for the polymerization include benzoyl peroxide, lauroyl peroxide, caproyl peroxide, di-i-propyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, and t-butylperoxydioxide. Organic peroxides such as valates and t-butylperoxy-2-ethylhexanate; 2,2′-azobis-i-butylnitrile, 2,2′-azobis-2,4-dimethylvaleronitrile, 2,2′- Azo compounds such as azobis-4-methoxy-2,4-dimethylvaleronitrile and the like can be used alone or in combination.
Among the polymerization initiators, an organic peroxide having a high hydrogen abstraction ability is used when polymerizing a monomer that gives a polymer portion A that is insoluble in an organic solvent in an organic solvent in which a polymer soluble in the organic solvent exists. It is preferable to do. By using a polymerization initiator having a high hydrogen abstraction ability, an unstable hydrogen atom in the soluble polymer is efficiently extracted, and a monomer that gives an insoluble polymer portion A is added thereto. As a result, a graft or block copolymer in which the soluble polymer portion and the insoluble polymer portion are bonded to each other is formed, and the generated insoluble polymer in the organic solvent forms a particle nucleus together with the insoluble polymer portion of the graft or block copolymer. Can be formed.
The usage-amount of a polymerization initiator is the range of 0.01-5 mass parts normally with respect to a total of 100 mass parts of monomers, Preferably it is 0.02-2 mass parts.

  Moreover, as an example of a chain transfer agent, the compound as described in the paragraph number [0051] of Unexamined-Japanese-Patent No. 2000-095917 can be used. When using a chain transfer agent, the usage-amount is preferable 0.005-3 mass parts with respect to a total of 100 mass parts of monomers.

In the resin composition for pastes of the present invention, the ratio of the non-aqueous dispersion resin is preferably 30 parts by mass or more, more preferably 30 to 60 parts by mass, and still more preferably 40 to 100 parts by mass of the organic solvent. 50 parts by mass. In other words, the nonvolatile content in the paste resin composition of the present invention is preferably 30% by mass or more, more preferably 30 to 60% by mass, and still more preferably 40 to 50% by mass.
When the ratio of the non-aqueous dispersion resin to the organic solvent is 30 parts by mass or more, that is, the non-aqueous dispersion resin is in a range that is not too small relative to the organic solvent, a composition with a high non-volatile content can be obtained, and baking is performed using this. When done, heat shrinkage is suppressed. Further, when the ratio of the non-aqueous dispersion resin is 60 parts by mass or less, that is, the non-aqueous dispersion resin is not too much in the organic solvent, the low viscosity is maintained and good thixotropic properties are exhibited.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

<Preparation of copolymer (B) solution>
As shown below, a copolymer (B) was prepared as the soluble polymer B of the non-aqueous dispersion resin in the present invention.

(Production Example 1-1)
A reactor equipped with a stirrer, a reflux condenser, a sequential dropping device, and a thermometer was charged with 630.4 parts by mass of butyl carbitol acetate (BCA; boiling point = 247 ° C.) and 111.3 parts by mass of methanol (MeOH). . Then, in another container, a monomer mixture consisting of 87.6% by mass of 2-ethylhexyl methacrylate (2EHMA), 9.4% by mass of isobutyl methacrylate (iBMA), and 3.0% by mass of 2-hydroxyethyl methacrylate (2HEMA) 500 parts by mass were prepared, 125 parts by mass of which was charged into the reactor, and 0.02 parts by mass of 2,2′-azobis (2,4-dimethylvaleronitrile) (ABN-V) was added as a polymerization initiator. . After the addition, it was heated and kept at reflux temperature for 20 minutes. Further, a mixture comprising 375 parts by mass of the remaining monomer mixture, 70.8 parts by mass of BCA, 12.5 parts by mass of MeOH, and 1.25 parts by mass of ABN-V was successively added dropwise over 120 minutes. After maintaining the same temperature for 40 minutes, 53.2 parts by mass of BCA, 9.3 parts by mass of MeOH, and 1.25 parts by mass of ABN-V were successively added dropwise over 30 minutes. After maintaining at the same temperature for 190 minutes, it was cooled after being diluted with BCA, and a copolymer (B1) containing 2EHMA / iBMA / 2HEMA (= 87.6 / 9.4 / 3.0 [mass ratio]) copolymer. ) A solution was obtained.

Composition of monomer used above, glass transition temperature (Tg), solubility parameter (SP value), nonvolatile content of the obtained copolymer (B1) solution, BH viscosity (25 ° C.), and weight average molecular weight (Mw) is shown in Table 1 below.
The viscosity was measured at 25 ° C. at a rotation speed of 10 rpm with a BH viscometer (manufactured by Toki Sangyo Co., Ltd.). Mw is a value obtained by gel conversion chromatograph (GPC) and measuring TSK-GEL GMHXL (Tosoh styrene polymer filler) as a column and converting to polystyrene.

(Production Examples 1-2 to 1-7)
A copolymer (B2) to (B7) solution was obtained in the same manner as in Production Example 1-1 except that the composition of the monomer in Production Example 1-1 was changed as shown in Table 1 below. It was.

(Production Example 1-8)
In Production Example 1-1, except that butyl carbitol acetate (BCA) was changed to terpineol (boiling point = 217 to 218 ° C), and the monomer composition was changed as shown in Table 1 below. In the same manner as in Example 1-1, a copolymer (B8) solution was obtained.

(Production Example 1-9)
Production Example 1 except that in Example 1-1, butyl carbitol acetate (BCA) was changed to texanol (boiling point = 255 ° C.) and the monomer composition was changed as shown in Table 1 below. In the same manner as in Example 1, a copolymer (B9) solution was obtained.

(Production Example 1-10)
A reactor equipped with a stirrer, a reflux condenser, a sequential dropping device, and a thermometer was charged with 212.5 parts by mass of butyl carbitol acetate (BCA) and 37.5 parts by mass of methanol (MeOH). Next, in another container, 600 parts by mass of a monomer mixture composed of 62.0% by mass of 2-ethylhexyl methacrylate (2EHMA), 20.0% by mass of butyl acrylate (BA), and 18.0% by mass of methyl methacrylate (MMA). 150 parts by mass were charged into the reactor, and 0.10 parts by mass of 2,2′-azobis (2-methylbutyronitrile) (ABN-E) was added as a polymerization initiator. After the addition, it was heated and kept at reflux temperature for 20 minutes. Further, a mixture comprising 450 parts by mass of the remaining monomer mixture, 85.0 parts by mass of BCA, 15.0 parts by mass of MeOH, and 0.5 parts by mass of ABN-E was successively added dropwise over 120 minutes. After maintaining at the same temperature for 40 minutes, 63.8 parts by mass of BCA, 11.2 parts by mass of MeOH, and 1.50 parts by mass of ABN-E were sequentially added dropwise over 30 minutes. After maintaining at the same temperature for 190 minutes, dilute with BCA, extract MeOH, dilute the extracted with BCA, cool and then 2EHMA / BA / MMA (= 62/20/18 [mass ratio] ) A copolymer (B10) solution containing a copolymer was obtained.
Composition of monomer used above, glass transition temperature (Tg), solubility parameter (SP value), nonvolatile content of the obtained copolymer (B10) solution, BH viscosity (10 rpm, 25 ° C.), and weight The average molecular weight (Mw) is shown in Table 1 below. The viscosity and Mw were measured by the same method as described above.

(Production Example 1-11)
17.5 parts by mass of ethyl cellulose was dissolved in 100.0 parts by mass of butyl carbitol acetate (BCA) to obtain a copolymer (B11) solution.

(Example 1): Preparation of non-aqueous dispersion resin In a reactor equipped with a stirrer, a reflux condenser, a sequential dropping device, and a thermometer, 26.2 parts by mass of butyl carbitol acetate (BCA), methanol (MeOH) 4 .7 parts by mass and 509.85 parts by mass of the copolymer (B1) solution obtained in Production Example 1-1 were charged and heated to the reflux temperature. After the temperature rise, a monomer mixture 356. consisting of 71.0% by mass of ethyl acrylate (EA), 9.0% by mass of methyl methacrylate (MMA), and 20.0% by mass of 2-hydroxyethyl methacrylate (2HEMA). 9 parts by mass, 102.6 parts by mass of BCA, 49.8 parts by mass of MeOH, and 2.79 parts by mass of t-butylperoxy 2-ethylhexanate (PB-O) were sequentially added dropwise over 90 minutes. And kept at the same temperature for 60 minutes. Thereafter, 74.3 parts by mass of BCA and 7.43 parts by mass of PB-O were successively added dropwise over 90 minutes and kept at the same temperature for 90 minutes. Diluted with BCA, extracted MeOH, diluted with BCA and cooled.

As described above, a resin dispersion solution (resin composition for paste) in which a non-aqueous dispersion resin in which an EA / MMA / 2HEMA copolymer is bonded to a 2EHMA / iBMA / 2HEMA copolymer is dispersed in BCA as an organic solvent. Product).
The non-volatile content concentration of the obtained resin dispersion solution was 45.3% by mass.

  Composition of monomers used above, glass transition temperature (Tg), solubility parameter (SP value), nonvolatile content of the obtained resin dispersion, BH viscosity (10 rpm, 25 ° C.), and weight average molecular weight (Mw) ) Is shown in Table 1 below. The viscosity and Mw were measured by the same method as described above.

(Examples 2 to 10)
In Example 1, the copolymer (B1) is replaced with the copolymers (B2) to (B9) having the monomer composition described in Table 1 below, and the type of organic solvent, insoluble polymer of the polymer structure portion A is used. A resin dispersion solution (resin composition for paste) was obtained in the same manner as in Example 1 except that the monomer composition was changed as shown in Table 1 below. The nonvolatile content concentration of each resin dispersion solution was as shown in Table 1 below.

(Comparative Example 1)
In Example 1, the copolymer (B1) was replaced with the copolymer (B10) of Production Example 1-10, and this was used as a resin dispersion solution (resin composition for paste). The nonvolatile content concentration was as shown in Table 1 below.

(Comparative Example 2)
In Example 1, the copolymer (B1) was replaced with the copolymer (B11) of Production Example 1-11, and this was used as a resin dispersion solution (resin composition for paste). The nonvolatile content concentration was as shown in Table 1 below.

(Evaluation)
The following evaluation was performed about each of the resin dispersion solution (resin composition for pastes) prepared in said Examples 1-10 and Comparative Examples 1-2. The evaluation results are shown in Table 2 below.

-1. Viscosity ratio (screen printability)
The resin dispersion was placed in a constant temperature water bath at 25 ° C., and after adjusting the temperature to 25 ° C., the viscosity was measured with a BH viscometer (manufactured by Toki Sangyo Co., Ltd.) at 4 rpm and 20 rpm. A viscosity ratio represented by 4 rpm / 20 rpm was determined from the obtained viscosity and used as an index for evaluating thixotropic properties. Evaluation was performed according to the following evaluation criteria. The higher the viscosity ratio, the higher the thixotropic property and the better the screen printability.
<Evaluation criteria>
A: The viscosity ratio is 1.4 or more, a structure having a good height and shape can be obtained by one screen printing, and excellent screen printability is exhibited.
B: The viscosity ratio is 1.3 or more and less than 1.4, a structure having a relatively good height and shape is obtained, and good screen printability is exhibited.
C: The viscosity ratio is 1.2 or more and less than 1.3, and it is difficult to obtain a desired shape, and the screen printability is slightly inferior.
D: The viscosity ratio is less than 1.2, and the screen printability is inferior.

-2. Firing property
The resin dispersion is dried under reduced pressure at 200 ° C. for about 10 minutes, and about 10 mg of the resin obtained by drying is placed on an aluminum dish, and is placed in a nitrogen atmosphere using a thermogravimetric / analytical apparatus (EXSTAR6000 manufactured by SII Nanotechnology) The temperature was raised from room temperature to 600 ° C. at a temperature raising temperature of 10 ° C./min. Then, it cooled to room temperature, observed the state of the residue visually, and evaluated according to the following evaluation criteria.
<Evaluation criteria>
A: Almost no residue on the aluminum pan.
B: There is some residue on the aluminum pan.
C: There are many residues in the aluminum dish.

As shown in Table 2, it can be seen that in the Examples, the obtained resin solution (resin composition for paste) is prepared to have a high non-volatile content, and has a high viscosity ratio and good thixotropic properties. Therefore, the resin solutions of the examples are suitable for screen printability, and when screen printing is performed, it is possible to form a good structure having a higher shape than conventional ones. In addition, the remaining carbon component after firing was significantly reduced.
On the other hand, in the comparative example, the thixotropy is inferior, and a structure having a desired height and shape cannot be obtained when screen printing is performed. When the amount of printing is increased in order to realize a desired height, sagging is likely to occur, and as a result, a fine pattern cannot be expected, for example, when a fine pitch cannot be obtained when forming an electrode pattern for solar cells.

  The resin composition for paste according to the present invention has a high non-volatile content, low viscosity, and excellent thixotropic properties. Therefore, the paste resin composition is suitable as a coating liquid used for screen printing, and has few residues such as residual carbon after firing. From this point, it is suitable for uses such as a paste for firing, and is suitably used for, for example, the formation of ribs for plasma displays (PDP) and the formation of electrodes for solar cells (PV).

Claims (6)

An organic solvent,
A polymer structure part A in which an insoluble polymer insoluble in an organic solvent is aggregated, and an organic solvent-soluble soluble polymer B that is at least partially bonded or adsorbed to the polymer structure part A, are dispersed in the organic solvent. Water-dispersed resin,
A resin composition for pastes. The organic solvent has a solubility parameter (SP value) of 8.0 (cal / cm ³ ) ^{0.5 to} 10.0 (cal / cm ³ ) ^0.5 and a boiling point of 180 ° C. to 280 ° C. The resin composition for paste according to claim 1.   The resin composition for paste according to claim 1 or 2, wherein at least one of the insoluble polymer of the polymer structure portion A and the soluble polymer B is a (meth) acrylic resin.   The resin composition for paste according to any one of claims 1 to 3, wherein the organic solvent is at least one of butyl carbitol acetate, terpineol, and texanol. The SP value (SPA) of the insoluble polymer of the polymer structure portion A is larger than the SP value (SPB) of the soluble polymer B, and the SPA and the SPB satisfy the following formula 1. The resin composition for pastes according to item 1.
SPA-SPB <1.5 (Formula 1)   The ratio (A / B; mass ratio) of the polymer structure portion A to the soluble polymer B in the organic solvent is 0.5 / 1 or more and 5/1 or less. The resin composition for pastes according to claim 1.