JP2010241968A5 - Acrylic resin for fired paste, method for producing the same, and fired paste composition - Google Patents

Description

The present invention relates to a firing resin useful as a component of a fired paste composition used in the production of electrodes of electronic components, printed wiring boards, liquid crystal display panels, plasma display panels, and the like, and a method for producing the same.

Although the molded object by inorganic substance and the pattern formed by it are useful in the field | areas, such as an electronic material, as a method of forming such a molded object and pattern, conventionally, metal powder, metal oxide powder, A method in which inorganic powders such as fluorescent powder and glass frit are mixed with a binder resin to prepare a fired paste composition, a predetermined shape and pattern are formed from this paste, and then fired to thermally decompose organic matter. It has been known.

In particular, for applications used in screen printing and dipping, it is necessary to reduce the binder component contained as much as possible in order to increase the filling rate of the filler component to be sintered. Therefore, the binder component is required to have a viscosity characteristic that expresses a high viscosity satisfying screen suitability and dip suitability at a low solid content. Therefore, as the binder component, a solvent-based binder resin dissolved butyral resin or ethyl cellulose or the like in an organic solvent is Ru is used.

The gist of the present invention resides in an acrylic resin for baking paste containing a constituent unit derived from alkyl methacrylate and having a residual initiator amount of 30 ppm or less.

By using the acrylic resin of the present invention, it is possible to prepare a fired paste composition with little deterioration in the properties of the metal conductor after firing.

The present invention will be described in detail below.
The acrylic resin of this invention contains the structural unit derived from an alkyl methacrylate, and the amount of residual initiators is 30 ppm or less.
By including a structural unit derived from alkyl methacrylate, a fired paste having excellent printability and low temperature fireability can be obtained.
In addition, alkyl methacrylate has a low content of oxygen atoms that may oxidize the filler, and can prevent deterioration of the properties of the metal conductor after firing.

Further, the acrylic resin of the present invention needs to have a residual initiator amount of 30 ppm or less. This is because the oxidation of the filler during firing is reduced by setting the residual initiator amount to 30 ppm or less. As a method for measuring the amount of the remaining initiator, a known method such as titration analysis, ion chromatography analysis, gas chromatography analysis, IR analysis, NMR analysis, or the like can be used and appropriately selected according to the initiator used. I can do it. A preferable range of the remaining initiator amount is 10 ppm or less.
Moreover, the acrylic resin of this invention may contain the structural unit derived from monomers other than the structural unit derived from alkyl methacrylate.
Specific examples include alkyl acrylates, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl ( meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 6-hydroxy. Vinyl polymerizable monomers having a hydroxyalkyl group such as hexyl (meth) acrylate; (meth) acrylic acid, 2- (meth) acryloxyethyl hexahydrophthalic acid, 2- (meth) acryloxypropyl hexahydrophthalic acid, 2 -(Meth) acryloxyethyltetrahydrophthalic acid, 2- (meth) acryloxypropyltetrahydrophthalic acid, 5-methyl-2- (meth) acryloxyethylhexahydrophthalic acid, 2- (meth) acryloxyethylphthalic acid , 2- (meth) acryl Carboxyl group-containing vinyl monomers such as xylpropylphthalic acid, 2- (meth) acryloxyethyl oxalic acid, 2- (meth) acryloxypropyl oxalic acid, crotonic acid, fumaric acid, maleic acid, itaconic acid, sorbic acid; Acrolein, diacetone acrylamide, formyl styrene, vinyl alkyl ketone, (meth) acrylamide pivalin aldehyde, diacetone (meth) acrylate, acetonyl acrylate, 2-hydroxypropyl acrylate acetyl acetate, acetoacetoxyethyl (meth) acrylate, butanediol-1 , 4-acrylate-acetylacetate, vinyl monomers having an aldehyde group or carbonyl group such as acrylamidomethylanisaldehyde; (meth) acrylamide, crotonamino Amide group-containing vinyl monomers such as N-methylolacrylamide; Epoxy group-containing vinyl monomers such as allyl glycidyl ether and glycidyl (meth) acrylate; Aromatic vinyl monomers such as styrene and α-methylstyrene; Nitriles such as acrylonitrile Group-containing vinyl monomers; olefin monomers such as butadiene; and vinyl halide monomers such as vinyl chloride. These may be used alone or in combination of two or more.

Furthermore, the acrylic resin of the present invention may have a cross-linked structure with a cross-linking agent component having two or more unsaturated double bonds capable of radical polymerization in order to improve printability.

Next, the manufacturing method of the acrylic resin for baking paste of this invention is demonstrated.
<Polymerization process>
In the present invention, an emulsion is obtained by emulsion polymerization using a monomer containing 60% by mass or more of alkyl methacrylate with respect to all monomers.
By containing 60% by mass or more of alkyl methacrylate with respect to the total monomer amount, a fired paste composition having excellent printability and excellent low-temperature fireability can be obtained.

Examples of the alkyl methacrylate include monomethacrylates such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, and lauryl methacrylate. Two or more of these can be used in combination. Among these, it is preferable to use butyl methacrylate from the viewpoint of baking properties.
Further, monomers other than alkyl methacrylate may be included, and specific examples include alkyl acrylates, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl ( meth) acrylate, and 3-hydroxypropyl (meth). Vinyl polymerizable monomers having a hydroxyalkyl group such as acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate; (meth) acrylic acid, 2- (meth) acryloxyethyl hexahydrophthalic acid, 2- (meth) acryloxypropylhexahydrophthalic acid, 2- (meth) acryloxyethyltetrahydrophthalic acid, 2- (meth) acryloxypropyltetrahydrophthalic acid, 5-methyl-2- (meth) acryloxyethylhexa Hydrophthal 2- (meth) acryloxyethylphthalic acid, 2- (meth) acryloxypropylphthalic acid, 2- (meth) acryloxyethyl oxalic acid, 2- (meth) acryloxypropyl oxalic acid, crotonic acid, fumaric acid Carboxyl group-containing vinyl monomers such as maleic acid, itaconic acid, sorbic acid; acrolein, diacetone acrylamide, formyl styrene, vinyl alkyl ketone, (meth) acrylamide pivalin aldehyde, diacetone (meth) acrylate, acetonyl acrylate, 2- Aldehyde groups or carbonyls such as hydroxypropyl acrylate acetyl acetate, acetoacetoxyethyl (meth) acrylate, butanediol-1,4-acrylate-acetyl acetate, acrylamide methyl anisaldehyde Vinyl monomers having amide groups; amide group-containing vinyl monomers such as (meth) acrylamide, crotonamide, N-methylolacrylamide; epoxy group-containing vinyl monomers such as allyl glycidyl ether and glycidyl (meth) acrylate; styrene, α-methylstyrene Aromatic vinyl monomers such as nitrile group-containing vinyl monomers such as acrylonitrile; olefin monomers such as butadiene; vinyl halide monomers such as vinyl chloride, and the like. These may be used alone or in combination of two or more.
Furthermore, in the case of emulsion polymerization, in order to improve printability, a crosslinking agent component having two or more unsaturated double bonds capable of radical polymerization may be added.

Examples of the crosslinking agent component include ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, and 1,4-butane di (meth) acrylate. Diol, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, neopentyl glycol hydroxypivalate di (meth) acrylate, polypropylene glycol di (meth) acrylate, di ( (Meth) acrylic acid polytetramethylene glycol, trimethylolpropane tri (meth) acrylate, ethoxylated trimethylolpropane tri (meth) acrylate, propoxylated trimethylolpropane tri (meth) acrylate, Rintori (meth) acrylic acid esters, ethoxylated glycerin tri (meth) and acrylic acid ester. Two or more of these can be used in combination.
The crosslinking agent component is preferably added in the range of 0.1 to 5% by mass. This is because by setting the crosslinking agent component to 0.1% by mass or more, it is possible to impart high viscosity to a composition in which an acrylic resin is dissolved in a solvent, and it can be suitably used as a fired material. . Preferably it is 0.5 mass% or more. Moreover, it is because by making a crosslinking agent component 5 mass% or less, while being able to provide the outstanding baking property to a polymer, the solubility to a solvent becomes favorable. Preferably it is 1 mass% or less.
The initiator used in carrying out the emulsion polymerization is not particularly limited, but it is preferable to use only a water-soluble initiator for ease of washing. Examples of the water-soluble initiator include persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate, water-soluble organic peroxides such as t-butyl peroxide, 2,2′-azobis [N- (2- Water-soluble azo compounds such as carboxyethyl) -2-methylpropionamidine] hydrate, 2,2′-azobis [2- (2-imidazolin-2-yl) propane], hydrogen peroxide, and the like can be used.

<Residual initiator reduction process>
In the present invention, a method of adding a reducing agent to the emulsion obtained by emulsion polymerization to decompose the remaining initiator in the emulsion, or a powder obtained after spray-drying the emulsion obtained by emulsion polymerization Residual initiator is reduced by a method of washing.

In the case of the method of decomposing the remaining initiator in the emulsion by adding a reducing agent, the reducing agent for decomposing the initiator is not particularly limited. For example, Rongalite, thiourea dioxide, sulfites, ascorbic acids, etc. Can be used.

In the method of washing the obtained powder after spray-drying the emulsion, the washing of the powder is not particularly limited as long as it is a solvent in which the remaining initiator dissolves. For example, water, methanol or the like can be used, but water is particularly preferable from the viewpoint of handling. The solvent is dispersed by adding at least three times the solvent of the weight of the powder, and after stirring, the powder is separated by filtration. Further, heating the dispersion to about 40 ° C. during stirring can increase the solubility of the remaining initiator, which is preferable in that the cleaning effect is further improved.

<Drying process>
In the case of the method of decomposing the remaining initiator in the emulsion by adding a reducing agent, the obtained emulsion is spray-dried, and then obtained by spray-drying the emulsion from which the acrylic resin for baking paste of the present invention is obtained. In the case of the method for washing the obtained powder, the obtained wet powder is dried to form a powder, whereby the acrylic resin for a fired paste of the present invention is obtained.

The acrylic resin of the present invention can be used in preparing a fired paste composition using an inorganic filler such as a metal powder, a metal oxide powder, a fluorescent powder, an inorganic powder such as glass frit. Among these, it is preferable to use as a resin for aluminum paste using aluminum as a filler, which tends to cause deterioration of physical properties of a molded product after firing due to oxidation.
The organic solvent for preparing the fired paste composition of the present invention is not particularly limited, but examples thereof include α 1 , β 3 , γ-terpineol, propylene glycol monomethyl ether, ethyl - 3-ethoxypropionate, ethylene glycol monomethyl ether, ethylene Glycol monobutyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate , Isophorone, 3-methoxybutyl acetate, benzyl alcohol, 1-octanol, 1-nonaol, -Ethyl-1-hexanol, 1-decanol, 1-undecanol, 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol and the like can be mentioned. These may be used alone or in combination of two or more. Alternatively, an organic oligomer may be used as a solvent in order to obtain a photosensitive paste that is photocured after coating.

As described above, according to the present invention, by using an acrylic resin having an alkyl methacrylate as a main component and a reduced residual initiator, in particular, for making a baking paste composition using an easily oxidized filler such as aluminum, baking is performed. A fired paste composition capable of suppressing subsequent deterioration in physical properties can be obtained.

<Various evaluations>
(Residual initiator amount)
After the initiator in the acrylic resin was extracted with pure water (40 ° C. × 1 hour), analysis by titration based on JIS-K8252 was performed to quantify the remaining initiator.
(Electric resistivity)
Acrylic resin 1 . 5 parts were dissolved in 8.5 parts of diethylene glycol monobutyl ether acetate. Thereto, 70 parts of an aluminum dispersion (Asahi Kasei Aluminum Paste MH-8801) was added and kneaded to prepare an aluminum paste composition. The obtained aluminum paste composition was printed on a ceramic substrate to a width of 0.5 mm × thickness of 0.03 mm with a screen printer, dried at 150 ° C. for 30 minutes, and then fired at 750 ° C. for 30 minutes. Then, an aluminum conductor was prepared, and the resistivity was calculated by measuring the resistance value with a tester.
A: Less than 1.0 × 10 ⁻⁶ Ω · m ○: Less than 3.0 × 10 ⁻⁶ Ω · m ×: 3.0 × 10 ⁻⁶ Ω · m or more

<Example 1>
Add 100 parts of water and seed monomer (see Table 1) to a polymerization apparatus that can be heated and cooled, add 0.1 part of initiator while stirring at 150 rpm in a nitrogen atmosphere, and heat at 80 ° C. for 1 hour. Polymerized to form seed particles. A pre-emulsion using 25 parts of deionized water, 0.5 part of an emulsifier, and monomer A (see Table 1) was added dropwise to this reaction solution over 2 hours, and then superheated at 80 ° C. for 1 hour. Subsequently, a pre-emulsion using 25 parts of deionized water, 0.5 part of an emulsifier, and monomer B (see Table 1) was dropped into the reaction solution over 2 hours. Five minutes after the completion of dropping, 0.05 part of sodium bisulfite was added as a reducing agent, and the mixture was kept at 80 ° C. for 1 hour to complete the emulsion polymerization. The obtained reaction solution was filtered through a nylon filter cloth having an opening of 45 μm to obtain an emulsion B.
The obtained emulsion B was spray-dried at an inlet temperature of 150 ° C. and an outlet temperature of 60 ° C. with a spray dryer (CL-8 type, manufactured by Okawara Chemical Co., Ltd.) to obtain polymer powder B. The amount of the remaining initiator of the obtained polymer powder B was below the lower limit of quantification (<1 ppm). When the electrical resistivity was measured using the polymer powder B, it was 1.23 × 10 ⁻⁶ Ω · m.

<Example 2>
100 parts of water and seed monomer are added to a polymerization apparatus capable of heating and cooling, and 0.1 part of an initiator is added while stirring at 150 rpm in a nitrogen atmosphere, and polymerization is performed by heating at 80 ° C. for 1 hour, and seed particles Formed. To this reaction solution, 25 parts of deionized water, 0.5 part of an emulsifier, and a pre-emulsion using monomer A were added dropwise over 2 hours, followed by superheat polymerization at 80 ° C. for 1 hour. Subsequently, a pre-emulsion using 25 parts of deionized water, 0.5 part of emulsifier and monomer B was dropped into the reaction solution over 2 hours, and then kept at 80 ° C. for 1 hour to complete the emulsion polymerization. The obtained reaction solution was filtered through a nylon filter cloth having an opening of 45 μm to obtain an emulsion C.
The obtained emulsion C was spray-dried at an inlet temperature of 150 ° C. and an outlet temperature of 60 ° C. with a spray dryer (CL-8 model, manufactured by Okawara Chemical Industries Co., Ltd.) to obtain polymer powder C.
In an apparatus capable of heating and cooling, 20 parts of polymer powder C and 100 parts of water were added and dispersed while stirring. The powder was washed by heating to 40 ° C. and heating for 1 hour. The powder dispersion was filtered using a Kiriyama funnel, and the polymer powder was dried to obtain a polymer powder C ′. The amount of the remaining initiator of the obtained polymer powder C ′ was below the lower limit of quantification (<1 ppm). When the electrical resistivity was measured using the polymer powder C ′, it was 0.79 × 10 ⁻⁶ Ω · m.
<Comparative Example 1>
When the polymer powder C obtained in Example 2 was not washed, the residual starting amount of the polymer powder C was 45 ppm. Furthermore, when the electrical resistivity was measured using the polymer powder C, it was 3.21 × 10 ⁻⁶ Ω · m.
<Comparative example 2>
100 parts of water and seed monomer are added to a polymerization apparatus capable of heating and cooling, and 0.1 part of an initiator is added while stirring at 150 rpm in a nitrogen atmosphere, and polymerization is performed by heating at 80 ° C. for 1 hour, and seed particles Formed. To this reaction solution, 50 parts of deionized water, 1 part of an emulsifier, and a pre-emulsion using monomer A were added dropwise over 4 hours. The emulsion polymerization was terminated by maintaining at 80 ° C. for 1 hour. The obtained reaction solution was filtered through a nylon filter cloth having an opening of 45 μm to obtain an emulsion D.
The obtained emulsion D was spray-dried with a spray dryer at an inlet temperature of 150 ° C. and an outlet temperature of 60 ° C. to obtain polymer powder D. The amount of the remaining initiator of the obtained polymer powder D was 48 ppm. When the electrical resistivity was measured using the polymer powder D, it was 3.68 × 10 ⁻⁶ Ω · m.

As is clear from the above results, the fired paste composition of the present invention can reduce the oxidation of the filler during firing by using the acrylic resin with less residual initiator of the present invention as a binder for firing. It is very useful industrially.

Claims (4)

An acrylic resin for baking paste containing a constituent unit derived from alkyl methacrylate and having a residual initiator amount of 30 ppm or less . A polymerization step of emulsion-polymerizing a monomer containing 60% by mass or more of alkyl methacrylate with respect to all monomers using an initiator to obtain an emulsion, and a step of adding a reducing agent to the emulsion to reduce the remaining initiator A method for producing an acrylic resin for a firing paste according to claim 1, further comprising a drying step of drying the emulsion after the residual initiator reducing step to form powder. A polymerization step of emulsion-polymerizing a monomer containing 60% by mass or more of alkyl methacrylate with respect to all monomers using an initiator to obtain an emulsion, and spray-drying the emulsion, and then washing the obtained powder The manufacturing method of the acrylic resin for baking paste of Claim 1 including the drying process which dries and pulverizes the wet powder obtained by the process of reducing a residual initiator, and the process of reducing a residual initiator. The baking paste composition containing the acrylic resin for baking pastes of Claim 1 , an inorganic filler, and the organic solvent.