JPS63260855A - Binder for forming inorganic sintered body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a binder used when an inorganic powder such as alumina is fired to form an inorganic sintered body such as a ceramic.

[Prior art]

In general, inorganic sintered bodies are formed by forming an inorganic sintered body composition into granules using a spray dryer using a press molding method, a rubber press molding method, or a tape shape using a doctor blade method. However, in these molding methods, various binders are usually used.

For example, water-soluble binders used in granules of materials molded by press molding or rubber press molding include polyvinyl alcohol, alkali salts of carboxymethyl cellulose, alkali salts of acrylic acid resin, and isobutylene-maleic anhydride copolymer. Alkali salts of combined resins are known, but these water-soluble binder resins have problems such as poor slurry stability and fluidity, molds that are too hard and cause severe damage to molds, and poor mechanical strength of molded products. Inferior. glossiness,
It has drawbacks such as the inability to obtain a product with excellent smoothness.

On the other hand, the doctor blade method is a method mainly used for manufacturing inorganic sintered sheets used for IC substrates and the like. The binder used in this method is generally a so-called solvent-based binder in which a binder such as butyral resin or acrylic resin is dissolved in an alcohol such as methanol or ethanol or a solvent such as methyl ethyl ketone or toluene, which creates a poor working environment and is flammable. including the dangers of

As a method to overcome the drawbacks of this solvent system, methods have been proposed that use polyvinyl alcohol, water-based acrylic resin, polyethylene oxide, water-based or water-dispersed polyurethane resin as a binder, but when these binders are used, As mentioned above, the stability of the slurry.

Poor fluidity and hard molded products can damage the molding machine.
Another problem is that they are weak and require post-processing. Furthermore, in order to overcome these drawbacks, Japanese Patent Application Laid-Open Nos. 181763-1982, 35059-1980, 167470-1980, 1674-1980
Although various binders have been reported, such as in No. 71 and JP-A-57-7861, they have not yet been satisfactory.

〔the purpose〕

An object of the present invention is to provide a molded product that is superior in appearance, such as transparency and gloss, and is not stiff and strong, unlike the conventional binders described above.

It is an object of the present invention to provide a binder for molding an inorganic smoked body which causes less damage to molded products and has good workability.

〔composition〕

According to the present invention, an inorganic sintered material comprising an aqueous emulsion having an average particle size of 1100 nm or less, having a crosslinked structure, and preferably having a glass transition temperature lower than the value calculated by the weight fraction method. A body shaping binder is provided.

First, the binder for forming an inorganic sintered body of the present invention has an average particle diameter of 10 On+m or less, preferably 80 nm.
The following aqueous emulsion is required.

In an aqueous emulsion, a film is essentially formed by filling and fusing particles, so the average particle size is required to be small; however, in the present invention, as described above, the average particle size is 100 mm. Since the particle size is limited to 50 nm or less, preferably 80 nm or less, it has good permeability and can sufficiently wet the microscopic surface of the inorganic material to be molded. It becomes possible to greatly improve various properties such as gloss and gloss.

When the average particle size exceeds 1100n, the permeability is insufficient and the microscopic surface of the inorganic material to be molded cannot be sufficiently wetted, and the fusion properties (denseness) when the film is formed are poor. Since the film may lack gloss and smoothness, the intended purpose of the present invention cannot be achieved.

A second feature of the binder for molding an inorganic sintered body of the present invention is that it is an aqueous emulsion having a crosslinked structure within and/or between its particles.

That is, the binder of the present invention has ionic bonds, hydrogen bonds, condensation reactions, or polymerization between the functional groups of the raw material unsaturated monomers, or between these and the functional groups of the emulsifier, within the particles and/or between the particles. Transparency due to crosslinking through reaction, etc.

It is estimated that it forms an adhesive film with excellent adhesiveness, water resistance, solvent resistance, and mechanical strength.

Further, the binder of the present invention preferably uses an aqueous emulsion having a glass transition temperature lower than the value calculated by the weight fraction method, preferably 3° C. or more, more preferably 5° C. or more lower.

Glass transition temperature (Tg) is the temperature at which a polymer changes from a glassy, hard state to a rubbery state when heated. This glass transition temperature is influenced by various structural factors, and generally has a crosslinked structure. It is known that the glass transition temperature of a polymer increases, and that adding a plasticizer to the polymer lowers the glass transition temperature.

Furthermore, if the glass transition temperature of a component that is a structural factor of a polymer is known, the glass transition temperature of the polymer can be determined from the following equation using the weight fraction method.

W^; Weight fraction of component A WB ; Weight fraction of component B "g A ; Glass transition temperature of component A" K s
; Glass transition temperature of component B This glass transition temperature is influenced by various structural factors, and generally in the case of a polymer with a crosslinked structure, the glass transition temperature is higher, and depending on the degree of crosslinking, it may be higher by 5 to 7 °C. It is also known that adding a plasticizer to a polymer lowers the glass transition temperature.

On the other hand, for aqueous emulsions, the minimum film-forming temperature is known as the lowest temperature at which a film is formed by filling and fusing one particle, and there is a proportional relationship between this minimum film-forming temperature and the glass transition temperature. Recently, the present inventors have found that the film has a crosslinked structure, the minimum film forming temperature or the glass transition temperature of the formed film is lower than that calculated by the weight fraction method, and the tensile strength is lower than that calculated by the weight fraction method.

We have discovered an ultrafine particle aqueous emulsion that forms a film with good mechanical strength such as modulus strength, and found that this emulsion is useful as a binder for molding inorganic sintered bodies.

That is, the aqueous emulsion used in the present invention.

Despite having a crosslinked structure, as mentioned above, it has the ability to form a film that shows a glass transition temperature lower than the value calculated by the weight fraction method, so unlike the conventional film, it exhibits an excellent plasticizing effect and can be easily formed. Since the glass transition temperature of the resulting film is lowered, the minimum film-forming temperature is also lowered in proportion to this, resulting in excellent transparency, adhesiveness, and smoothness even at room temperature. Furthermore, it is possible to form a hard film with good mechanical strength such as tensile strength and modulus strength. In this case, as is clear from the comparative example below, if the glass transition temperature of the film to be formed is higher than the value calculated by the weight fraction method, the aqueous emulsion will not have sufficient plasticizing effect, so the minimum film forming temperature will be At room temperature, the film may not form, or even if it does, cracks or mesh-like streaks will form on the film, resulting in the formation of a film with excellent transparency, smoothness, and adhesion as in the present invention. Can not do it.

Furthermore, it is hard and lacks mechanical strength such as tensile strength and modulus strength, making it difficult to obtain a hard and strong film.

In addition, other characteristics of the aqueous emulsion used in the present invention are:
It has excellent dispersion stability over a long period of time.

That is, the aqueous emulsion which is an essential component of the binder for forming an inorganic sintered body used in the present invention has an average particle size of 110
This one is less than 0n.

Even when subjected to a forced heating dispersion stability test at 45°C for one week, there was virtually no change in the average particle size, and even if there was a change, it was usually a particle distribution with an average particle size of 150 nm or less. It shows the particle size distribution of mountain distribution, and even when the rate of change is large, the particle size distribution of the first mountain with an average particle diameter of less than 150rv+ is 97% or more, and the second mountain due to aggregation of 5 rice grains is 300n■ The above particle size distribution shows a two-peak distribution with extremely small peaks of 3% or less, and the particle size distribution of the average particle size is extremely small.

Furthermore, the aqueous emulsion, which is an essential component of the binder for forming an inorganic sintered body used in the present invention, exhibits an extremely low rate of change in its average particle diameter even when subjected to a long-term storage stability test at 25°C for 6 months. small.

Therefore, in the aqueous emulsion according to the present invention, particles do not substantially coalesce or agglomerate with each other over time, and do not generate coarse particles. Viscosity change.

Furthermore, since there is no change in appearance, it shows excellent dispersion stability over a long period of time, and has extremely high storage stability.

The reason why the aqueous emulsion, which is an essential component of the binder for forming an inorganic sintered body of the present invention, exhibits excellent dispersion stability as described above is not necessarily clear, but since its average particle size is 1100 nm or less, one particle The Brownian motion between them is relatively active.

In addition, due to the fact that no polymerizable emulsifier remains in the system and the properties of each particle surface, each particle is sufficiently protected, preventing coalescence and aggregation between particles, and coarse particles The basic factor is presumed to be that it does not encourage the formation of

In addition, in the present invention, in order to further improve the dispersion stability of the aqueous emulsion, conventionally known compounds such as P-hydroxydiphenylamine, N,N'-diphenyldiamine, and 2,5-di-tart-butylhydroquinone are used. A polymerization inhibitor or a polymerization terminator may also be added.

In addition, the average molecular weight of the low crosslinked aqueous emulsion, which is an essential component of the inorganic sintered body molding/<inder of the present invention, is generally more than 100 degrees, and in most cases is from several thousand blades to hundreds of millions of degrees.
In addition, if the degree of crosslinking is high, the molecular weight may be several thousand blades to about 1 billion, and even higher.

The present invention will be explained in more detail below.

The aqueous emulsion, which is an essential component of the binder for molding an inorganic sintered body of the present invention, can be easily obtained by emulsion polymerization of unsaturated monomers.

This unsaturated monomer includes (meth)acrylic esters R1 represented by the following general formula (1) (wherein R1 and R8 are hydrogen or a methyl group, and R1 is an alkyl group having 1 to 18 carbon atoms). In addition, lower fatty acid vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, acrylonitrile,
Nitriles such as methachronitrile, styrenes such as styrene, α-methylstyrene, and chlorostyrene, vinyls such as vinyl chloride and vinyl bromide, vinylidene chloride,
Examples include vinylidenes such as vinylidene bromide, dienes such as butadiene, chloroprene, and isoprene, and vinylpyridine, but (meth)acrylic esters,
Preferably, lower fatty acid vinyl esters and styrenes are used.

In addition, in the aqueous emulsion which is the binder for forming an inorganic sintered body of the present invention, the unsaturated monomer to be copolymerized with the above unsaturated monomer may be used within the particles and/or between the particles of the aqueous emulsion to be produced. In order to further strengthen the crosslinked structure, unsaturated monomers with reactive functional groups are preferably used, but even unsaturated monomers without reactive functional groups can absorb active hydrogen in the emulsion polymerization system. It is also possible to use unsaturated monomers which can be converted into compounds having .

Examples of unsaturated monomers having such reactive functional groups include compounds represented by the following general formula (II)-(■). These monomers can be used alone or in combination of two or more, and if necessary, other copolymerizable unsaturated monomers can also be used in combination.

Ks-goi R9○H (in the formula, RltL -R4tRs eR@pi(t
, R1tns tsto+Ltt *t* and t are as follows.

Rt tRs is hydrogen atom or methyl group R4; alkylene group having 2 to 4 carbon atoms R6; direct bond, alkylene group having 1 to 3 carbon atoms, phenylene group or substituted phenylene group R6; oxygen atom or -NH- R7; hydrogen or Alkylol group R having 1 to 5 carbon atoms;
Hydrogen, an alkylol group having 1 to 5 carbon atoms, or an alkylol group having 1 to 5 carbon atoms
Alkyl group R9 of 5; C1-4 alkylene group A; methylene group or carbonyl group B; -CI, O- or carboxyl group; hydrogen atom,
Alkyl group having 1 to 3 carbon atoms, Ka? ;Hydrogen atom, carbon number 1
-3 alkyl group or -CH. COOH t1; Real number t from 1 to 20; Integer t from 0 or l; Integer from O-10) General formula (n), (m), (rV), (V), (VI),
Specific examples of compounds (■) and (■) include those shown below. Example of general formula (■) Glycidyl acrylate Glycidyl methacrylate Glycidyl tonate Glycidyl allyl ether Example of general formula (m) Hydroxyethyl acrylate Hydroxyethyl methacrylate Hydroxyethyl crotonate Hydroxyprobyl acrylate Hydroxypropyl methacrylate Hydroxybrobyl crotonate Hydroxybutyl acrylate Hydroxybutyl methacrylate Polyoxyethylene monoacrylate Polyoxyethylene monomethacrylate Polyoxyethylene monocrotonate Polyoxypropylene monoacrylate Polyoxypropylene monomethacrylate Polyoxypropylene monocrotonate Polyoxybutylene monoacrylate Polyoxybutylene monocroto nate hydroxyethyl allyl ether hydroxybropyl allyl ether hydroxybutyl allyl ether polyoxyethylene allyl ether polyoxypropylene allyl ether polyoxybutylene allyl ether Examples of general formula (rV) allylamine acrylamine methacrylamine aminostyrene α-methylaminostyrene Examples of general formula (V) Acrylamide Methacrylamide Aminopropyl methacrylamide Monomethyl acrylamide Monoethylacrylamide Diethylolaminopipyracrylamide General formula (V
Examples of I) Acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid and its monoester or anhydride of an alkyl group having 1 to 5 carbon atoms, fumaric acid and its monoester or anhydride of an alkyl group having 1 to 5 carbon atoms, maleic acid Alanidofumarate Alanide N-carpamoylmaleic acid amideN-carbamoyl fumaric acidamideExample of general formula (■)MethylallylthiolmethylmercabutostyreneExample of general formula (■)N-Methylolacrylicamide N-Methylolmethacrylic acidamideN -Methylolcrotonic acid amide N-(2-hydroxyethyl)acrylic acid amide N-(
2-hydroxyethyl) methacrylic acid amide N-(2-
Hydroxyprobyl) Acrylic Acid Amide N-(2-Hydroxyprobyl) Methacrylic Acid Amide The ratio of the above unsaturated monomer to the unsaturated monomer having a reactive functional group is 9
9/1-60/40 (weight), preferably 99/
1 to 90/10 (weight) is 8゛. This usage rate is 99
If it is larger than 71, the degree of crosslinking within and between the particles of the aqueous emulsion produced will be small, and if it is smaller than 60/40, the emulsion copolymerizability will be poor, and a large amount of aggregates will be formed, or the film forming property will be poor or formation. This may cause cracks in the coating.

As mentioned above, the emulsifier used when emulsion polymerizing the aqueous emulsion, which is an essential component of the binder for forming an inorganic sintered body of the present invention, using the unsaturated monomer, has an average particle size of 1100 nm or less. Any emulsifier can be used as long as it has a crosslinked structure and forms a film that preferably shows a glass transition temperature lower than the value calculated by the weight fraction method, but particularly preferred emulsifiers include the following: Polyoxyalkylene ethylenically unsaturated carboxylic acid polyesters (hereinafter referred to as poly(
It is abbreviated as meta)acroyl emulsifier. ), general formula (X
), (X[), (X11), (XIII) and (XI
V) betaine ester type emulsifier and general formula (
XV).

Examples include ether carboxylic acid type emulsifiers represented by (XVI) and (X■).

(In the formula, R,, R,, R1゜tRitjttt+LaJ
z**FitstFitsrRtt tRt@tax
tax Pal Pal tag #a@Pa? Pa
l Pal tall tGvJIri, N, T, X,
Y and V are as follows.

R1, R hydrogen or methyl group R1°; alkylene group having 2 to 4 carbon atoms Rxz; alkyl group or alkenyl group having 8 to 30 carbon atoms, which may be linear or branched, preferably carbon atoms 8 -18 Ryu: Alkylene group having 1 to 5 carbon atoms Rzi*Rx*tRzs; Alkyl group having 1 to 3 carbon atoms or -0, H, and OH, which may be the same or different.

Rx5Jzt; an alkyl group having 6 to 20 carbon atoms or hydrogen, at least one of which is an alkyl group having 6 to 20 carbon atoms R1;; hydrogen, an alkyl group having 1 to 30 carbon atoms or an alkenyl group al, a #a) ta4# astas+av: indicates the average number of added moles a,; a real number from 1 to 50, preferably the number of added moles of alkylene oxide in the molecule is 8 or more ax: a real number of 0''20 as; Rza and 1 (tt) When either one is an alkyl group, a real number from 0 to 20; when both Ro and 1iit are an alkyl group, a real number from 1 to 30 R4: a real number a from 1 to 30; a real number from 0 to 20 , : real number a from 0 to 20, ; real number a from 0 to 20, ; integer a from 0 or 1, : real number p from 2 to 20; integer q from 2 to 5: integer ♂R2゜-o from O-3 -cnHan-gz(Rzx)&-0-)ttst
Rzal hydrogen or alkyl group with 1 to 2 carbon atoms R21; hydrogen or +R0゜0+TrIIH or n; integer gl of 1 to 10; integer g of 0 to 5; integer axI of o-io; real number of 1 to 50 ( co-)z-cH4 and or (CH3), -CH-
4-CH,- and y: real number R11pR*a of 1-5; hydrogen or alkyl group Y' having 1-20 carbon atoms; alkylene group having 3-8 carbon atoms, nitrogen 1. Cl-0- or ■-〇- T; Direct bond, oxygen, sulfur; Hydrogen or inorganic anion
In particular, ultra-fine pre-crosslinked aqueous particles with an average particle diameter that have a dense, more advanced cross-linked structure within and/or between particles, and form a film that exhibits a glass transition temperature lower than the value determined by the calculation formula. In order to obtain an emulsion, (a)
A poly(meth)acroyl emulsifier represented by the above general formula (IX), (b) the above general formula (X), (XI), (Xn
), (XI[[), (XIV) and (c) the above general formula (XV), (X
VI), (X■) and (a)/(b)=1/9 to 9/1 or (a)/
(c) = weight ratio of 1/9-9/1, preferably 1/4-
Used in a 4/1 weight ratio. If this usage ratio is less than 1/9, the degree of crosslinking within and/or between particles of the aqueous emulsion produced will be small, and if it is greater than 9/1, the average particle diameter of the aqueous emulsion produced may become large.

Additionally, known anionic, nonionic and cationic surfactants may be added as necessary, specific examples of which include higher alcohols, higher alcohol oxidized alkylene adducts, alkylphenol oxidized alkylene adducts, and styrenated surfactants. Sulfate type of phenol alkylene oxide adduct, olefin sulfonate type such as a-olefin, long chain alkyl amine alkylene oxide adduct and di-long chain alkyl amine alkylene oxide adduct, respectively.
Examples include ammonium salt type, sodium salt of N-(1,2-dicarboxyethyl)-N-octadecylsulfonic acid monoamide, and dialkylsulfosuccinate.

Further, when obtaining an aqueous emulsion which is an essential component of the binder for forming an inorganic sintered body of the present invention.

When using betaine esters as emulsifiers.

pH in the emulsion polymerization step is less than 6, preferably 3-6
If the pH is 6 or higher, a large amount of agglomerates having physical properties significantly different from those of the aqueous emulsion of the present invention will be produced in the emulsion polymerization process, which is not preferable.

In the present invention, to obtain an aqueous emulsion, a conventionally known emulsion polymerization method can be used as is in the presence of the unsaturated monomer and the emulsifier. For example, in the presence of a polymerization initiator corresponding to o, i-s weight percent of the unsaturated monomer, a polymer of unsaturated monomers is
It is sufficient to carry out emulsion polymerization by emulsifying and dispersing it in water at a concentration of 0 to 60% by weight.6 As the polymerization initiator, a water-soluble single initiator or a water-soluble redox initiator used in ordinary emulsion polymerization is used. Examples of such substances include hydrogen peroxide alone, a combination of radicalized hydrogen and a carboxylic acid such as tartaric acid, citric acid, and ascorbic acid, hydrogen peroxide and oxalic acid, sulfinic acid, and salts thereof, or In addition to combinations with dialdehydes, water-soluble iron salts, etc., peroxides such as persulfates, percarbonates, perborates, etc.
, 2'-azobis(2-amidinoproban) and its salts,
Water-soluble azo initiators such as 2.2'-azobis (N, N'-dimethylene-isobutyramidine) and its salts, 4.4'-azobis (4-cyanovaleric acid) and its salts can be used. However, particularly preferably used polymerization initiators are the above-mentioned water-soluble azo initiators.

Furthermore, water-soluble nonionic polymer substances, anionic polymer substances, cationic polymer substances, and the like can be used in combination. Furthermore, plasticizers commonly used in conventional methods, pH m
1L agent can also be used in combination if necessary.

Examples of nonionic polymeric substances include polyvinyl alcohol, dextrin, hydroxyethyl starch, starch derivatives such as hydroxyethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and the like.

Examples of anionic polymer substances include anionized hydroxyethyl cellulose, anionized starch, anionized guar gum, and anionized chitosan.

Examples include polymers such as carboxymethyl cellulose and anionized polyvinyl alcohol.

Further, examples of the cationic polymer substance include cationized hydroxyethyl cellulose, cationized starch, cationized guar gum, cationized chitosan, and polymers such as cationic (meth)acrylic acid amide and dimethyldiallylammonium chloride.

These nonionic polymeric substances, anionic polymeric substances, and cationic polymeric substances can be used alone or in combinations of two or more, but the amount added is 0.0000000000000000000000000000000000000000000000000000. 05~5 Weight 2° Preferably 0.1~
It is appropriate to use triple perspective.

Further, as the plasticizer, phthalate ester, phosphate ester, etc. can be used. Furthermore, as a PH1ll agent, salts such as sodium carbonate, sodium bicarbonate, and sodium acetate may be used together in a range of 0.01 to 3% by weight, but as mentioned above, when a betaine ester type emulsifier is used as an emulsifier, It is desirable to adjust the pH to less than 6.

In order to mold an inorganic sintered body such as a ceramic or a mold using the binder for an inorganic sintered body molded body of the present invention, an inorganic powder such as a metal, an inorganic substance, or an organic substance and the aqueous emulsion are preferably mixed in terms of solid content. A composition consisting of inorganic powder/aqueous emulsion = 99.910.1 to 8/2, preferably 99/l to 9/1 is mixed in a weight ratio of 99.91 to 9/1, and this product is processed by extrusion molding, press molding, doctor blade method, etc. It can be easily obtained by subjecting it to the following molding method.

Specific examples of inorganic powders include alumina, silicon oxide, silicon nitride, zirconia, cordierite, and lithia (
LAS) ceramic, sodium oxide, hafnium oxide, barium titanate, lead zirconate titanate, zeolite, magnesia, beryllia, boron oxide, tin oxide,
Examples include aluminum titanate, zinc oxide, silica sand, olivine sand, zircon sand, and chromite sand.

〔effect〕

The binder for forming an inorganic sintered body of the present invention contains as an essential component an aqueous emulsion having an average particle size of 1100 nm or less, a crosslinked structure, and preferably a glass transition temperature lower than the value calculated by the weight fraction method. Therefore, in order to form a solid polymer film that is easy to work with, has good transparency and gloss, and is strong, the inorganic molded product obtained using this product has good transparency and gloss. It has an excellent appearance in terms of physical properties, is strong, and has good mechanical strength.

Furthermore, although the molded product is strong and strong, it does not have the extreme hardness of conventional products, so it is extremely unlikely to be damaged during molding.

[Example] Next, in order to explain the present invention in more detail, Examples are shown below.

Example 1 (Preparation of aqueous emulsion) Emulsifier 8 shown in Table 1 was placed in a glass reaction vessel equipped with a thermometer, stirrer, reflux condenser, nitrogen introduction tube, and dropping funnel.
．． 0 parts by weight and 150 parts by weight of water were charged and dissolved, and the inside of the system was purged with nitrogen gas. Separately, 156 parts by weight of an unsaturated monomer mixture consisting of 75 parts by weight of ethyl acrylate, 75 parts by weight of methyl methacrylate, 4.5 parts by weight of N-methylolacrylamide and 1.5 parts by weight of water was prepared. 1
5 parts by weight were added to the reaction vessel and emulsified at 40°C for 30 minutes. After heating to 60°C, polymerization initiator 2
, 2'-Azobis(N,N'-dimethyleneisobutyramidine) hydrochloride was dissolved in 48.5 parts by weight of water to 9.0×10-"moQa/Ω of the water phase, and added to the above reaction vessel. Immediately after adding the unsaturated monomer, the remaining unsaturated monomer was continuously dropped into the reaction vessel over 30 minutes, and polymerization was carried out at 60°C.After the dropwise addition of the unsaturated monomer was completed, the unsaturated monomer was aged at 60°C for 60 minutes. , an aqueous emulsion was prepared.

[Evaluation of water-based emulsion]

The average particle diameter, crosslinkability and glass transition temperature of the aqueous emulsion thus obtained were measured by the following methods.

Average particle size: Coulter Submicron Particle Analyzer (manufactured by Coulter Electronics, USA, Cou
The average particle diameter was measured using a ltar Model N4 type).

Crosslinking: 30g of aqueous emulsion adjusted to have a solid content of 40% by weight & 12cm x 14a
The mixture was uniformly cast onto a glass plate of 2.0 m in diameter and air-dried at 25°C. The film obtained in this way was 20×40!
The sample was cut into a 20° C. cut and immersed in a petri dish filled with benzene at 20° C. for 48 hours, and evaluated as follows based on the degree of swelling and solubility of the film.

0 ; Film area before immersion in benzene (2cm + x 4
am) or slightly swollen.

Δ: The degree of swelling is large and the film shape is impaired.

X: The film was dissolved in benzene and became a uniform liquid.

Film forming property: A film was formed by air drying at 25°C, and the condition of the formed film was visually evaluated.

0: Forms a smooth and uniform film.

Δ: Forms a film with mesh-like streaks.

X: No film is formed.

Glass transition temperature (Tg) Thermal analysis measuring instrument 91 (SSC500 manufactured by Seiko Electronics Co., Ltd.)
Tgti was measured using 0DSC200). The calculated value of Tg was calculated by the weight fraction method (described above).

[Evaluation of film characteristics]

Aqueous emulsion 30 with vR adjusted solid content to 20% by weight
The weight part was uniformly cast onto a 12 cm x 14 cm glass plate, air-dried at 25°C to form a film, and the film properties were evaluated. Film properties were evaluated based on the following criteria.

Transparency: The haze value of the film was measured using an integral light transmittance measuring device according to JIS K6714.

Water resistance: Cut the film into a size of 2as x 4cm,
The sample was immersed in a petri dish filled with water at ℃ and the time required for the film to turn white was visually determined.

0; 10 days or more Δ; 2 days or more, 10 days Nisshin Groove; less than 2 days Adhesion: The surface of the film was touched with a finger and the sticky feeling was evaluated according to the following criteria.

0; No sticky feeling.

Δ; Slightly sticky.

×; Sticky.

Elongation and strength: Dumbbells were made according to JIS K-6781, and the tensile strength at break, elongation rate, and 50%, 1
00% and 200% modulus strengths were measured.

[Preparation of molded object and performance evaluation]

Alumina (AL-1605G-1, purity 99.0wt%
, average particle size 0.5 μm, obtained by mixing 100 parts by weight of Showa Light Metal N, 24 parts by weight of deionized water, and 0.6 parts by weight of a dispersant (acrylic acid/acrylic acid ester copolymer NH4 salt) in a ball mill for 24 hours. To the resulting slurry were added 24.5 parts by weight of the aqueous emulsion with a solid content concentration of 40% obtained above, 3 parts by weight of polyethylene glycol with a molecular weight of 200, and 2 parts by weight of ethyl calpitol, and further milled with a ball mill for 24.5 parts by weight.
Mixed for an hour. The resulting slurry was degassed under reduced pressure and then stagged onto a polyester sheet with a thickness of 1.21 mm.
Dry for one day and night at ℃ to form a tape-shaped green sheet (10c
+a x 22cm) was created. The state of cracks, tensile strength, and green density of the green sheet were measured. The state of cracks and tensile strength were evaluated based on the following criteria.

Condition of cracks: There are no cracks at all on the OH10cm x 22cm sheet surface.

Δ: There are some cracks on the sheet surface of 10 cm x 22 cm.

X; There are quite a lot of cracks on the sheet surface of the 10c+5X22c irises.

Tensile Strength According to JIS K6301, the sheet was punched into a dumbbell size 1 shape, and the breaking strength was measured at a tensile speed of 0.3 cm/min.

The properties of the aqueous emulsion and the performance of the molded article obtained by the above method are shown in Tables 1 and 2.

Samples Nos. 1 to 4 are examples of the present invention.1 Since the ultrafine particles of the aqueous emulsion of the present invention have a crosslinked structure within the particles and/or between the particles, a molded product using these as a binder has no cracks. It can be seen that it also has excellent breaking strength.

Note that sample No. 5-7 is a comparative example.

In accordance with JIS K-6781, dumbbells were prepared from the aqueous emulsions of Sample &1 (invention) and Sample &5 (comparative example), and a stress stress test was conducted. As is clear from Figure 0, which shows the results, the product of the present invention forms a film that is harder and more tenacious than that of the comparative example.

Example 2 Consisting of 8.0 parts by weight of the emulsifier shown in Table 3, 90 parts by weight of ethyl acrylate, 60 parts by weight of methyl methacrylate, 4.5 parts by weight of N-methylolacrylamide, and 2.5 parts by weight of water. 157 parts by weight of unsaturated monomer and 3.0 parts by weight of potassium persulfate as a polymerization initiator. OX 10′″”+ole/
Aqueous phase flooding, sodium thiosulfate3. OX 10”mola
/water phase n and water phase steel5. It was dissolved in 47.5 parts by weight of water so that the ratio of OX 10-ole/water was obtained, and emulsion polymerization was carried out in the same manner as in Example 1 to prepare an aqueous emulsion.

The properties of the aqueous emulsion thus obtained, the properties of the film formed by air drying at 20 ° C., and the performance as a binder for forming an inorganic sintered body were measured in the same manner as in Example 1.
evaluated. The results are shown in Tables 3 and 4, sample No. 8
-11 are examples of the present invention.

Samples &12 to 14 and 14' are comparative examples.

Measurements were made on molded products at 30°C.

Example 3 154.5 parts by weight of an unsaturated monomer mixture consisting of 60 parts by weight of n-butyl acrylate, 90 parts by weight of styrene, and 4.5 parts by weight of 2-hydroxyethyl methacrylate, and 8.0 parts by weight of the following emulsifier. 4.0 parts by weight and 9.0 parts by weight of the polymerization initiator shown in Table 5. OX 10-3mo
Dissolved in 50 parts by weight of water so that le/aqueous phase Q,
Emulsion polymerization was carried out in the same manner as in Example 1 at the polymerization and ripening temperature shown in 5 to prepare an aqueous emulsion. The properties of the obtained aqueous emulsion, the properties of the film obtained by air drying at 20° C., and the performance as a binder for forming an inorganic sintered body were measured according to Example 1. The results are shown in Tables 5 and 6.

Samples Nos. 15, 16, 17, 19, 20 and 21 are examples of the present invention, and samples Nos. 18 and 22 are comparative examples.

In addition, the mechanical strength of the films of Sample Nos. 15-17, 19, 20 and 21 are all elongation 150% or more, tensile strength (strength at break) 150 g/a# or more, and the glass transition temperature is the calculated value. Compared to 24°C, film forming properties were also good at temperatures below 20°C.

Example 4 The following emulsifiers E-1-E-5C, in weight parts shown in Table-4,
l(,5o-C31(Go-CC,)1.0■rQ(,
-COONa E -2E-5 Separately, m
*I. Emulsion polymerization was carried out in the same manner as in Example 1 to prepare an aqueous emulsion. The properties of the obtained aqueous emulsion, the properties of the film formed by air drying at 25° C., and the evaluation as a binder for forming an inorganic sintered body were measured according to Example 1. The results are shown in Table-7.

Samples &23 to 34 are examples of the present invention. Furthermore, sample N
The mechanical strength of the films Q23 to 34 all have an elongation rate of 15.
0% or more, and the tensile strength (strength at break) was 150 kg/aJ or more. In addition, in the same manner as in Example 1, sample NQ2
Using the aqueous emulsions Nos. 3 to 34, performance evaluation as a binder for forming an inorganic sintered body was conducted. The results show that all of the aqueous emulsions of samples Th23 to 34 can be used as a binder for forming inorganic sintered bodies with cracking condition: Q, green density: 2.75 to 2.80 g/cj, and breaking strength: 100 kg/aJ or more. It was found that it has excellent performance as a binder.

Example 5 [Preparation of aqueous emulsion] 60 parts by weight of butyl acrylate, 90 parts by weight of styrene, N
- 3.0 parts by weight of methylolacrylic acid amide and 1.0 parts by weight of water.
5 parts by weight of an unsaturated monomer mixture, 0.582 parts by weight of 2,2'-azobis(N,N'-dimethyleneisibutyramidine) hydrochloride as a polymerization initiator, and an emulsifier shown in Table 8. Emulsion polymerization was carried out in the same manner as in Example 1 using the following to obtain an aqueous emulsion.

The properties and film characteristics of the obtained aqueous emulsion are shown in Example 1.
Measured in the same manner. The results are shown in Table-8.

[Preparation of molded object and performance evaluation]

100 parts by weight of new Flattery sand (silica sand from Cape Flattery on the northeast coast of Queensland, Australia) was charged into a mixer (Model S-13-2 manufactured by Enonami Seisakusho), and 100 parts by weight of new Flattery sand (silica sand from Cape Flattery, northeast coast of Queensland, Australia) was added to the mixer (Model S-13-2 manufactured by Enonami Seisakusho). Aqueous emulsion 3.0
Part by weight was added and stirred for 1 minute. 1. Next, the obtained silica sand mixture was lightly placed into a 50 m diameter x 50 mm cylindrical mold to fill it. 1. Next, the above mixture was first manually poured into the mold. After filling the mold evenly, replenish the mixture and press it 2 degrees from the top of the mold.

The sample was piled up until it reached a certain height, and evenly pressed down by hand for 1', the excess silica sand mixture was removed, and the sample was molded to obtain a test piece. The test piece is demolded when it becomes demoldable,
hardened. At this time, curing was controlled at 25°C.

The appearance, surface stability, and compressive strength of the test piece thus obtained were measured two days after molding.

The appearance and surface stability were evaluated based on the following criteria.

exterior 0: The test piece is glossy and has a good texture.

Δ: The gloss and texture of the test piece are also poor.

X: The test piece lacks luster and has a rough texture.

Surface stability (SSi%) Using a 10-mesh sieve, the rotor-tub large shaking method (
(manufactured by Teiko Seisakusho) for 2 minutes, and the surface stability was calculated using the following formula.

Nji of test piece before shaking The evaluation results of the test pieces are shown in Table-8.

Samples N118 and 35-37 are examples of the present invention,
Samples &39 and 40 are comparative examples.

In addition, the mechanical strength of the coatings of samples NQ35 to 37 are all elongation of 150% or more and tensile strength (strength at break) of 150.
kg/cd or more.

Furthermore, from Table 8, it can be seen that the aqueous emulsion of the present invention exhibits excellent effects as a binder for mold forming.

Example 6 The dispersion stability of the aqueous emulsions of the samples Nα1 to 34 was evaluated in the following manner. The results are shown in Table 9. The dispersion stability test was conducted as follows.

[Dispersion stability]

Aqueous emulsion 1 with solid content adjusted to 40% by weight
After putting 50g in a 220+a Q glass bottle and sealing it, it was left standing in a constant temperature room at 25°C for 6 months and in a constant temperature room at 45°C for one week, and the appearance, transmittance, viscosity, and average particle size were measured. The dispersion stability of the aqueous emulsion was evaluated.

The appearance, transmittance, viscosity, and average particle diameter were measured by the following methods.

Outside KA: Evaluated by visual judgment at 25°C according to the following criteria.

O: Transparent or translucent liquid Δ: Cloudy liquid The absorbance under light irradiation was determined, and the light transmittance (%) was calculated. Viscosity Using a Nibultz field type viscometer (B type viscometer manufactured by Tokyo Keiki Co., Ltd.),
The viscosity at 5°C was measured.

Average particle size: Coulter Submicron Particle Analyzer (Coal Tar Electronics, Inc., USA)
The average particle diameter was measured using a Modal NJ model.

In addition, samples 1-4.8 to 11.15 to 17.1 were subjected to a forced heating dispersion stability test that was left in a constant temperature room at 45°C for one week.
Example 1 Aqueous emulsions of 9-21 and 23-34
A film was formed according to Example 1, and the film characteristics and performance as a binder for forming an inorganic sintered body were measured and evaluated. Transparency, water resistance, adhesiveness, solvent resistance (crosslinking),
Figure 2 shows a graph of the changes in particle size distribution before and after the dispersion stability test, in which good results were obtained in terms of both mechanical strength and mechanical strength, which were almost the same as those of Examples 1.2.3 and 4.
A) and FIG. 2(B).

In addition, sample 7 in Table 9 (1) had many extremely large particles and could not be measured due to 1 poor dispersion after being left standing at 45°C for one week.
The diagram shows the change in particle size distribution after being left standing for 6 months.

compared.

[Brief explanation of drawings]

Figure 1 shows the results when stress-strain samples were performed on dumbbells made from aqueous emulsions of the present invention product (sample Nα1) and comparative product (sample Nn5: film forming temperature 35°C) according to JIS K-6781. These are the measurement results. Solid line: Inventive product Dashed line: Comparative product Figures 2 (A) and 2 (B) are the inventive product (sample &
1) and the aqueous emulsion of comparative products (sample & 7)
It is a graph showing the change in particle size distribution after standing at 5° C. for 6 months. Patent author Lion Co., Ltd. Agent Patent attorney Toshiaki Ikeura (and 1 other person) Strain ε (am) 2nd (Sample 2 Sample diagram (A) No. 1) Particle size (nm) No. 7)

Claims (2)

[Claims] (1) A binder for an inorganic sintered compact, characterized in that the average particle diameter is 100 nm or less and an aqueous emulsion having a crosslinked structure is an essential component. (2) The binder for an inorganic sintered compact according to claim 1, wherein the aqueous emulsion has a glass transition temperature lower than the value calculated by the weight fraction method.