JPH0280453A - Graphite paste composition - Google Patents

Abstract

PURPOSE:To make it possible to perform highly elaborate pattern printing by improving burning behavior by mixing a specified acrylic polymer with a fine graphite powder and an organic solvent. CONSTITUTION:42-99.9wt.% alkyl methacrylate (a) (e.g., isobutyl methacrylate) is mixed with 0-8wt.% unsaturated carboxylic acid (b), 0-40wt.% hydroxylated alkyl (meth)acrylate (c), 0-10wt.% nitrogenous alkyl (meth)acrylate (d) and 0-20wt.% copolymerizable monovinyl monomer (e) other than components (a)-(d) in such amounts that the amount of at least one component selected from the components (b)-(d) is at least 0.1wt.%, and the obtained mixture is polymerized to obtain an acrylic polymer (A). 100 pts.wt. said polymer is mixed with 33-333 pts.wt. fine graphite powder of a particle diameter of 0.1-3mum and an organic solvent of a b.p. >=150 deg.C (e.g., diethylene glycol monobutyl ether acetate) in such an amount that the viscosity of the obtained composition is 5000-200000cP.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a graphite paste for printing which provides highly fine micropatterned coatings.

[Conventional technology and issues]

In recent years, with the development of the electronics field, various electronic material devices such as hybrid ICs and LSIs have become lighter, thinner, shorter, and more precise.

Along with this, there has been a demand for high-definition patterns when manufacturing various devices. For example, printed circuit boards have become smaller, allowing more circuits to be integrated into a smaller area, and the line width of the circuits has also become more precise. In addition to circuits, high-definition patterns are
Several tens of micrometers for black matrix of high resolution CRT
It is necessary for many applications, such as stripes with a line width of

There are many methods for forming fine line patterns, such as photo-curing etching and printing methods. Photo-curing and electron beam curing etching methods can form fine line patterns with line widths on the order of several microns, but they require a large number of steps and require equipment. On the other hand, the printing method has the advantage of simple equipment and low equipment cost. It has been difficult to obtain patterns with good reproducibility.The reason for this is that no printing paste has been developed that meets the requirements for high-definition printing.

In addition, printing coatings are often subjected to operations such as sintering the filler by firing, or leaving only the components necessary for imparting functionality and volatilizing other unnecessary components. If there is any residue left after firing that is not removed, it may act as an impurity and have a negative effect on various physical properties, so it is important to leave only the components necessary for imparting functionality as much as possible.Therefore, we use a binder resin that is 5-sinterable and has no firing residue. The paste is indispensable, and the lower the complete firing temperature, the lower the energy consumption, which is industrially advantageous.The present invention is applicable not only to high-definition printing coatings (
The present invention relates to printing paste compositions which are also suitable for firing applications or which are useful as conductive materials at the same time.

[Means to solve the problem]

An object of the present invention is to provide a graphite paste composition for forming a coating film having a high-definition pattern width by screen printing without impairing the good thermal decomposition properties of acrylic resin. be.

That is, the gist of the present invention is (,99,9% by weight to 1 alkyl methacrylate 42, (b) 8% by weight to unsaturated carboxylic acid O, (
cl Hydroxyl group-containing alkyl (meth)acrylate O~4oNik%, fd) Nitrogen-containing alkyl (meth)acrylate O~10% by weight, (,1 Copolymerizable monovinyl other than the above a, b, c, and d components) An acrylic polymer compound obtained by combining a monomer mixture consisting of 0 to 20 fii % of monomers and containing at least 0.1 fii % of one of the following components:
00 parts by weight, 33 to 333 N parts of fine graphite powder (B), and a viscosity of the graphite paste composition of 5,000 to 20
This is a graphite paste composition consisting of an organic solvent (C1) having a boiling point of 150° C. or more in an amount of 0,000 centipoise.

Alkyl methacrylate (a), which is a component of the acrylic polymer A used in the present invention, needs to be contained in the monomers constituting the polymer A in an amount of 42 to 99.9% by weight. If it is less than 42% by weight, the sinterability will decrease,
Moreover, if it exceeds 99.9% by weight, the printability of the paste becomes poor, which is not preferable. Alkyl methacrylate (
Specific examples of a) include methyl methacrylate, ethyl methacrylate, and n-butyl methacrylate.

Examples include alkyl methacrylates having an alkyl group having 1 to 8 carbon atoms, such as inbutyl methacrylate, which are arbitrarily selected depending on required firing conditions such as firing start temperature, complete firing temperature, and heat loss rate.

In the present invention, at least one type selected from unsaturated carboxylic acids (b), hydroxyl group-containing alkyl (meth)acrylates (c), and nitrogen-containing alkyl (meth)acrylates (d) is used as a constituent component of the polymer zone). is 0
．． A content of 1118% is necessary to obtain good printability and graphite dispersibility. That is,
Considering the balance between the affinity between the resin and graphite and the printability of the paste, in order to uniformly form a fine line pattern on the base material, we did not add a 7-mer containing a polar group to the monomers constituting the polymer. must not.

When adding unsaturated carboxylic acid (b), the amount added is up to 8TL-Ji% in the monomer mixture,
If this amount exceeds 8% by weight, the sinterability will deteriorate, which is not preferable. Moreover, the preferable amount of unsaturated carboxylic acid added is 0.3 to 511 Lj1%. Unsaturated carboxylic acid (b
Specific examples of l include (meth)acrylic acid, itaconic acid, phthalic acid, and maleic acid.

When the hydroxyl group-containing (meth)acrylate is added, the amount added is up to 40i% by weight in the monomer mixture, and if this amount exceeds 40M1%, the sinterability will deteriorate, which is not preferable.

Specific examples of hydroxyl group-containing alkyl (meth)acrylates include hydroxyalkyl having an alkyl group having 1 to 4 carbon atoms, such as hydroxylethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxybutyl (meth)acrylate. Examples include (meth)acrylates.

When nitrogen-containing (meth)acrylate is added, the amount added is up to 101 rock% in the monomer mixture.
[If it exceeds t%, the sinterability will deteriorate, which is not preferable.

Specific examples of nitrogen-containing (meth)acrylates include 2-
(dibutylamino)ethyl acrylate, 3-(dibutylamino)propyl acrylate), 2-(cyphytylamino) 7-rohylacrylate, 2-((1,1-dimethylethyl)amine)ethyl acrylate, 2-diethylamino Ethyl methacrylate, 2-(diethylamino)cyclohexyl methacrylate, di-cyclohexylaminoethyl methacrylate, 2-dibutylaminoethyl methacrylate, dimethylaminoethyl methacrylate, 2,2-dimethyl-1,3-dimethylaminopropyl methacrylate, t- Examples include bunareaminoethyl methacrylate.

Further, in the present invention, in addition to the above-mentioned components a, b, c, and d, up to 203i% of Vr and other copolymerizable monovinyl monomers can be added to the monomer mixture. Specific examples of such monomers include alkyl acrylates such as ethyl acrylate, probyl acrylate, butyl acrylate, and other vinyl acetate,
Ethoxyvinyl acetate, vinyl propionate, methyl vinyl ether, ethyl vinyl ether, isopropyl vinyl ether, n-propyl vinyl ether, methyl vinyl ketone, ether vinyl ketone, n-propyl vinyl ketone, inpropyl vinyl ketone, r-methacryloxypropyltrimethoxysilane , γ-methacryloxypropyltri2(β-methoxyethoxy)silane, methacryloxymethyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, styrene, 0-methylstyrene, m-methylstyrene, p-methylstyrene, O-vinylbenzoic acid, ρ-vinylbenzoic acid, 2,4-
Dimethylstyrene, 3,4-dimethylstyrene, 3,5
-dimeterstyrene, etc., and can be used alone or in combination as long as no problem arises in sinterability.

Further, in the present invention, it is also possible to add a polyfunctional crosslinking additive within a range that does not impair sinterability.

The polymer particles of the present invention contain one part of the commonly known radical and one part of the solution.
It can be obtained by polymerization, emulsion polymerization, suspension polymerization, bulk polymerization, etc., and as long as the polymer composition is within the scope of the present invention, any method may be used as long as the polymer composition is within the scope of the present invention. You can choose any condition.

The fine graphite powder used in the present invention is added in an amount of 33 to 333 parts by weight per 100 parts by weight of the acrylic polymer (A). If it is less than 33 parts by weight, there will be a shortage of graphite and a uniform graphite film will not be obtained;
If the amount exceeds 33i [(part), the binder resin polymer (AlO amount will be insufficient, the leveling performance of the coating will decrease,
When printing by screen printing, etc., the coating surface not only becomes uneven (but also does not spread well as a printing paste).
, which is not preferable because the printability becomes poor.

The type of fine graphite powder is not particularly limited and may be selected arbitrarily depending on the purpose, but
For example, if a line width of several tens of micrometers is to be printed with sufficient accuracy, the particle diameter of the fine graphite powder is preferably 0.1 to 3 micrometers.

In the present invention, an organic solvent (C) having a boiling point of 150 DEG C. or higher is blended to make the viscosity of the graphite paste composition about 5,000 to 200,000 centipoise.

If the boiling point is less than 150° C., the viscosity changes during printing, which is not preferable. Further, the general Ki surface of graphite is lipophilic and tends to have affinity with nonpolar solvents. On the other hand, the surface of the substrate to be printed is glass, resin, etc., and has relatively high polarity, and the binder resin component designed to have affinity and adhesion with these surfaces also contains polar functional groups. Include it. So graphite,
Balancing the polarity of the binder resin and solvent,
In order to synergistically exhibit the effects of each component, it is necessary to select a solvent with a certain degree of polarity.

Such solvents (specific examples of CJ include diethylene glycol 7-ethyl ether acetate, diethylene glycol mottyl ether acetate, 2,2.4-
) Dimethyl 1,3-pentadiol monoisobutyrate, isophorone, 3-methoxybutyl acetate, α-
Examples include terpineol.

Further, depending on printing conditions, it is recommended to use a mixture of one or more of these solvents and a higher polarity solvent or a lower polarity solvent in order to obtain better printing performance.

The dispersion stability of graphite, which is a filler in graphite paste, depends on the type of graphite, but it also depends on the affinity of the binder resin and the solvent.

In particular, the viscosity behavior of graphite paste changes greatly depending on the combination of graphite and solvent. Therefore, when selecting a solvent, it is necessary to consider the viscosity that matches the intended printing conditions.

The composition of the present invention has a paste viscosity of 5,000 to 200.
It is used at about 000 centipoise.

If it exceeds 5,000 centipoise, K smearing etc. will easily occur at the edge of the film during printing, which is undesirable from the point of view of pattern reproducibility. This is not preferable because it causes unevenness on the surface of the coating film.

In the present invention, various commonly known additives such as plasticizers, dispersion stabilizers, leveling agents, and chicken-tropy imparting agents can be added as long as they do not impair the purpose.

Hereinafter, the present invention will be explained in more detail with reference to Examples. In the examples, "part" and "%" both refer to "11 parts" and "
% by weight.

Example 1 90 parts of inbutyl methacrylate (IBMA), 10 parts of hydroxyethyl methacrylate (HEMA) and 2.0 parts of azoinbutyronitrile were mixed in 120 parts of α-terpineol and 60 parts of diethylene glycol monobutyl ether acetate at 80°C for 10 minutes. Allowed time to react.

The obtained acrylic resin had an N weight average molecular weight of 100,000 and a solid content of the solution of 35%. 66.6 parts of fine graphite powder UFG-82 (manufactured by Showa Denko K.K.) was dispersed and kneaded in 100 parts of the obtained acrylic resin (solid content), and the viscosity was reduced to 25% with diethylene glycol monobutyl ether acetate.
+ OOOcpe (measured at 25° C. using an EHD type viscometer manufactured by Tokyo Keiki Co., Ltd.) to obtain a graphite paste composition.

The composition obtained as described above was printed onto a glass plate with a width of 100 μm and a thickness of 10 μm by screen printing.
The resulting graphite film was coated in the form of a nutraig, dried and fired, and the surface of the resulting graphite film was examined. Graphite film surface 40
Pattern accuracy and surface condition were evaluated using a 0x optical microscope. As a result, the pattern accuracy of the obtained graphite film surface (the measurement method is explained below Table 1 of Examples 2 to 100) was ±5 μm, and the coating surface was uniform, had complete hiding property, and had no unevenness. It formed a smooth surface.

Examples 2 to 10, Comparative Examples 1 to 5 Various components shown in Table IK were used as monomer components.The state of the printed coating film was evaluated in the same manner as in Example 1.The results are shown in Table 1.

Table 1 jBMA: Isobutyl methacrylate MAA: Methacrylic acid HEMA: Hydroxyethyl methacrylate DE:
Diethylaminoethyl methacrylate 100 μm pattern precision A fine 100 μm stripe pattern was printed on a glass plate using a #400 mesh screen, and the coating M width was evaluated using a 400x optical microscope.

○; Within 100 ± 5 μm △: 100 ± 5 μm or more and within 100 ± 10 μm x: 100 ± 10 tsrn or more 100 ± 20
The coating film pinhole composition within μm was printed on a glass plate, dried, and fired, and the presence or absence of pinholes on the coating film surface was examined using transmitted light and an optical microscope with a magnification of 400 times.

○: No pinhole ×: Pinhole present Sintering temperature increase rate 15℃/min s Sample amount 10■,
Firing temperature range: normal temperature → 400°C O: No residue Polymer (4
) and the same blending ratio of graphite as in Example 1 under the conditions shown in Table 2, and the state of the printed coating film was evaluated in the same manner as in Example 1.

The condition of the printed coating film on the glass plate was evaluated by making changes as shown in Table 2.

Table 3 Examples 14 to 17, Comparative Examples 8 and 9 88 parts of 10,000 MA, 2 parts of MAA, part HEMAIO, and 3.0 parts of azoisobutyronitrile were added to 1 part of α-tervineol.
The reaction was carried out in 70 parts at 80° C. for 10 hours. The weight average molecular weight of the obtained acrylic resin was 60,000, and the solid content of the solution was 37.
%Met.

Add graphite powder to 100 parts of the obtained acrylic resin (solid content)? Disperse 285 parts of FC-8, knead, and measure the viscosity of the paste composition with diethylene glycol 7-noethyl ether acetate. C was examined in reflected light using a 400x optical microscope.

○: Little unevenness (5 μm or less) No screen mesh marks △: Slightly more unevenness (・X: Screen mesh marks with many unevenness Examples 18 to 20, Comparative Example 10 By the same method as Example 1 The monomer components were polymerized at the ratios shown in Table 4, and the state of the coating film was evaluated.

Table 4 Examples 21 to 23 The state of the printed coating film was evaluated in the same manner as in Example 1, except that the amount of the chicken-tropy imparting agent was added in the amount shown in fi5. Note that Table 5 also shows the evaluation results for the composition of Example 1.

Table 5 [Effects of the Invention] As detailed above, by using the paste composition of the present invention, it is possible to print patterns with excellent firing properties and high definition, and the effects are extremely large.

Claims (1)

[Scope of Claims] (a) 42 to 99.9% by weight of alkyl methacrylate, (b) 0 to 8% by weight of unsaturated carboxylic acid, (c) 0 to 40% by weight of hydroxyl group-containing alkyl (meth)acrylate, ( d) 0 to 10% by weight of nitrogen-containing alkyl (meth)acrylate; (e) 0 to 20% by weight of other copolymerizable monovinyl monomers other than the above components a, b, c, and d, and b, c , acrylic polymer (A) 100 obtained by polymerizing a monomer mixture containing 0.1% by weight or more of at least one selected from component d.
parts by weight, 33 to 333 parts by weight of fine graphite powder (B), and a viscosity of the graphite paste composition of 5,000 to 20
A graphite paste composition comprising an organic solvent (C) having a boiling point of 150°C or higher in an amount of 0,000 centipoise.