FR2571716A1 - COMPOSITION FOR FORMING CERAMIC PRODUCTS, PROCESS FOR OBTAINING CERAMIC PRODUCTS THEREFROM, AND TREATMENT OF PRODUCTS FORMED OBTAINED - Google Patents

Abstract

A PULP MOLDING (A BARBOTINE CASTING) IS MADE USING A COMPOSITION OBTAINED BY MIXING A RESIN EMULSION WITH A BARBOTINE WHICH CONTAINS A POTTERY OR CERAMIC MATERIAL POWDER AS THE MAIN CONSTITUENT. THE COLOR PRODUCT OBTAINED WITH MECHANICAL STRENGTH ENABLING IT TO PERFORM FINISHING OPERATIONS WITHOUT NEED TO MAKE IT A BISCUIT COOKING. THE INVENTION ALSO ENABLES TO OBTAIN NEW CERAMIC PRODUCTS OF COMPLEX SHAPE BY ASSEMBLING SEVERAL FACTORY PRODUCTS FORMED IN ADVANCE FROM A CERAMIC MATERIAL AS A RAW MATERIAL, BY MEANS OF A JUNCTION AGENT THAT CONTAINS A CERAMIC MATERIAL AND A RESIN EMULSION AS MAIN CONSTITUENTS, THEN USING THE FACE PRODUCTS SO ASSEMBLED.

Description

The present invention relates to a composition for forming

  ceramic products, a process for forming ceramic products therefrom and a process for treating the resulting formed products, and more particularly, it relates to a ceramic product forming composition comprising the addition of a resin emulsion for a pottery or for a ceramic material (the term "ceramic material" refers, in its sense used herein, a so-called new ceramic material, such as alumina, zirconia, silica, ferrite, silicon carbide, silicon nitride or a solution

  sial solid (a compound containing silicon and aluminum)

  A process for forming ceramic products from said composition, and a process for treating the formed products, comprising the step of preparing a formed product formed from two or more formed products obtained in the indicated manner. above,

  then to cook the formed product assembled.

  In the slip casting or dough molding processes for the formation of ceramic products, cast products have previously been produced by adding suitable amounts of water, deflocculation agents, and the like to the pulps for the production of ceramic products. preparing slips, by pouring the slips into hygroscopic molds such as plaster molds, so that deposits of ceramic particles accumulate on the walls of the mold, due to water absorption by the molds, and after the completion of the accumulation of ceramic particles,

  by unmolding cast products from the molds that correspond to them

  lay. These cast products are then converted into ceramic products by stages such as drying, baking (or first baking), enameling and baking. When relying on the paste molding, it is necessary that the cast products have a mechanical strength to succeed in handling them during their operations.

  finishings and their transport. It is also indis-

  think that we can easily unmould molds that

correspond to them.

  When casting (slip casting) with a pottery paste, it was conventional practice to incorporate Gairome clay, Kibushi clay, or similar clays in a large proportion.

  in order to obtain the strength or mechanical fastness neces-

  to work with pulp molding. However, it was still necessary to subject the cast products, obtained by casting such pasta, a first firing (biscuit baking), so as to give them sufficient mechanical strength. In addition, the use of clay makes it difficult to produce high quality porcelain having the same translucent appearance as white porcelain. There was also an even more difficult problem due to the depletion of good quality clay resources. In these circumstances, there was a strong need for

  to develop a means of improving the strength,

  to provide sufficient strength or mechanical strength for casting products without using large volumes of clay.

  On the other hand, the possibility of using

  new ceramic products in industrial fields, because of their marvelous qualities of mechanical strength, heat resistance, resistance to abrasion and wear, etc., although conventional porcelain products were not not usable in such industrial fields. However, it can hardly be said that, in the current circumstances, their applications

  have progressed according to expectations. One of the main reasons

  limitation of the applications of the new ceramic products to be mentioned, lies in the difficulties of their

  training and treatment operations. -

  For the formation of porcelain products, a variety of forming methods can be used, including the above-mentioned pulp molding. The use of such training methods makes it easy to obtain even complicated configuration products. In the case of new ceramic products, their formation must be based on sheet forming, extrusion, compression molding, etc. As a result, it has not been easy to obtain products of complicated configurations. In other words, these training methods could only provide products of simple configuration, such as products in the form of plates, pipes, etc. It is thus possible to form complicated configuration products from new products. ceramics, provided that they can be molded into them. It was however impossible to form cast products of sufficient strength, using usual pastes as such. There has been a great need to develop a means of improving the strength that can give sufficient mechanical strength to cast products to be able to handle them during their operations.

finishing and their transport.

  The present inventors have carried out research

  pushed to solve the above problems.

  As a result, it has been discovered that the use of a resin emulsion as a strength-improving agent can improve the strength or mechanical strength of a cast product, whether a pottery paste or a ceramic material is used. . By the aforementioned method, it became possible

  to obtain new ceramic products of various confi-

  gurations, next to products in the form of plates and pipes. To obtain cast products of more complex configurations, it is conceivable to form two or more new cast ceramic products separately, as components, by the aforementioned method, to join them by an adhesive bond, then to bake the cast products. thus united. However, it was impossible to obtain the product being searched using any of the conventionally known adhesives, because these adhesives

  decompose under the effect of cooking and that

  The cast castings separate at their joining surfaces.

  The researches of the present inventors have, however,

  it is discovered that a new desired ceramic product of any desired form can be obtained, without the above-mentioned separation taking place, by bringing together the

  cast products mentioned above with a bonding agent

  placing a ceramic material and a resin emulsion,

  instead of conventional adhesives, then baking

cast products thus joined together.

  The subject of the invention is: a slip composition making it possible to form a cast product, having characteristics

  mold release systems and mechanical strength or

  to make it possible to carry out its finishing operations without having to undergo a baking of biscuit (first baking), by casting a slip of a paste for pottery or a ceramic material,

  as well as a paste molding process (barb casting

  tine) using such a composition;

  a slip composition making it possible to

  the first object of the invention, without using a clay-based constituent as a pottery paste, in a large proportion, during the casting of a slurry of the paste, as well as a paste-molding process using such a composition;

  a slip composition that makes it possible to apply

57 1 7 1 6

  a dough-molding process capable of giving sufficient mechanical strength to the cast product obtained to successfully handle the cast product during its finishing operations and its transport to a ceramic material, as well as to a process dough molding (slip casting) using such a composition; a process for producing a new ceramic product of complicated configuration from a material

  ceramic, as the main raw material.

  The above objectives are achieved by the

following aspects of the invention.

  1. A composition of formation of ceramics products

  formed by mixing a resin emulsion with a slurry which contains a pottery paste or a material

  ceramic as the main constituent.

  2. A method of forming ceramic products, comprising the step of slurrying (a slip casting) to the aforementioned slip composition.

  3. A process for treating a ceramic product

  as cast, comprising the following successive stages: A) mixing a resin emulsion with a slurry containing a ceramic material as a main component, so as to prepare a slip composition; B) two or more cast products are formed with the slip composition according to a paste-molding process (slip casting), said cast products having identical or different configurations, and in such a way that said cast products comprise at least one set of matching surfaces to be interconnected; C) applying a bonding agent which contains a ceramic material and a resin emulsion as main components to at least one of the mating surfaces of the cast products; D) the mating surfaces of the cast products are joined so as to join the cast products into a single unit cast product; and

  E) the unit cast product is baked.

  Although the paste molding process according to

  the invention makes it possible to obtain new ceramic products

  In the case of relatively complicated configurations, new ceramic products of desired complicated configurations can be obtained according to the pulp molding method according to the invention, provided that the process for treating cast products is applied, a process comprising stages

  such as those previously described in paragraph 3.

  By the term "pottery paste", as used herein, is meant a paste that was conventionally used and commonly used as pottery paste said paste containing feldspar, siliceous stone,

  Toseki (pottery stone), kaolin (or potting soil)

  wool, or earthenware) and / or clay, as the main

  component or major constituents.

  On the other hand, by the expression "ceramic material",

  as used here, must be understood to mean

  raw materials for ceramic products, including metal oxides such as alumina, zirconia, ferrite, silica, beryllium oxide, magnesia, titania, calcium oxide and zinc oxide , carbides such as silicon carbide and boron carbide,

  nitrides such as silicon nitride, aluminum nitride,

  boron nitride, borides such as aluminum boride, silicates, aluminates and zirconates of various metals, titanates such as barium titanate and strontium titanate, solid solutions

  such as sial, and their mixtures.

  By the term "resin emulsion (s)" is meant, for example, emulsions of acrylic resins

  containing (meth) acrylic ester resins, residues

  (meth) acrylic ester-vinyl acetate, resins

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7 1 7 1 6

  (meth) acrylic-styrene ester or (meth) acrylic vinyl chloride resins as main constituents, vinyl acetate resin emulsions containing vinyl acetate resins as main constituents, ethylene copolymer emulsions containing resins ethylene-acrylic ester or ethylene-vinyl chloride as the main constituents,

  synthetic rubber containing a styrene resin

  butadiene, methyl-butadiene methacrylate resin or acrylonitrile-butadiene resin, as main components, natural rubber emulsions, etc. Among these emulsions of resins, emulsions of acrylic resins

are appropriate.

  The quantity of resin emulsion to be added - AYte for pottery or ceramic material may vary, depending on the type

  of paste or ceramic material, its particle size

  and its particle size distribution, the type of resin emulsion, the type of ceramic product to be formed, etc. It can not be specified in a general way. However, it is generally necessary to add the resin emulsion in a proportion of about 0.1 to parts by weight of solids in the emulsion per 100 parts by weight of the dry pulp or material.

dry ceramic.

  Resin emulsions useful for carrying out the present invention can be prepared by a process

  emulsion polymerization known per se in the art.

  Indeed, they can be prepared each using water

  or a mixed solvent comprising water and an organic solvent

  water, such as an alcohol or acetone, as a fluid medium, by dispersing the corresponding monomer, if necessary by adding a surfactant, uniformly in the fluid, and then subjecting the monomer an emulsion polymerization in the presence of a water-soluble radical polymerization initiator,

25717 16

  and, if desired, a molecular weight control agent.

  and other chemical additives.

  As a polymerization initiator, it is

  possible to use a radical polymerization initiator

  usual calorific value, such as a peroxide, a oxidation

  reduction, a persulfate or an azo component.

  When using the surfactant, this may

  be any anionic surfactant, cationic

  that, non-ionic or amphoteric, or a mixture of any

  which combination of such surfactants.

  As a molecular weight control agent, a mercaptan, such as a dodecyl mercaptan, can be used

  tertiary or a normal dodecyl mercaptan, the tetra-

  carbon chloride, isopropyl alcohol, etc. In general, the polymerization is carried out at a

  temperature of 40 to 90 C in a reactor that was unloaded

  full of oxygen. The monomer, surfactant, molecular weight control agent, polymerization initiator and other desired chemical additives may be initially added to the reaction medium. Alternatively, portions may be added in portions or all after the start of the reaction. It is also possible to change operating conditions such as temperature and stirring conditions, as desired, during the reaction. We can perform the

  polymerization reaction continuously or in portions.

  The slip composition according to the invention, which is prepared by adding the resin emulsion to the pottery paste or to the ceramic material, is extremely

  stable and has a low viscosity and a good fluidity

  In other words, it is extremely suitable for molding. Products formed from this slip composition have excellent strength or

mechanical resistance.

  It can be incorporated into the slip used

  to prepare the ceramic product forming composition

  according to the invention and containing the pottery paste or the ceramic material as the main constituent, in addition to this paste or ceramic material, one or more deflocculation agents, sintering agents.

  ceramic raw materials other than those mentioned

  previously, additives, etc., if desired.

  As examples of deflocculation agents, mention may be made of inorganic deflocculation agents such as potassium orthosilicate (water glass), sodium carbonate and phosphates such as sodium phosphate

  and sodium tripolyphosphate, and deflocculation agents

  organic compounds such as sodium polyacrylate, a condensation product, naphthalene sulfonic acid and formaldehyde, and sodium lignin sulfonate. Its content may be, in general, from 0.02 to 2.0 parts by weight of solids per 100 parts by weight of the dry pulp

  or dry ceramic material.

  Examples of sintering agents are magnesia, boron, oxides of rare earth metals such as yttrium and lanthanum, and the like. Their content may be from 0.01 to 5.0 parts by weight per 100 parts by weight of the dry pulp or dry ceramic material. As additives other than those mentioned above, there is

  mention of mold release agents such as stearate

  calcium spleen, zinc stearate and emulsions of

  wax, pH modifying agents, including ammonia

  niac, organic amines such as triethenolamine, and organic acids such as oxalic acid and

  formaldehyde, and anti-foam agents such as anti-

  based on solicones and polyethers. Their contents can be understood for each between 0.01 and parts by weight of solids per 100 parts by weight.

  weight of the dry pulp or dry ceramic material.

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  In addition, it is also possible to use a wetting agent, an ion-fixing agent such as a chelating agent, a

  plasticizer and / or like agents.

  In the formation composition of ceramics

  In accordance with the invention, the pottery paste or the ceramic material is present in a proportion of 40 to 85 parts by weight of solids per 100 parts by weight of

  the formation composition of ceramic products.

  Each cast product formed by the process according to the invention has sufficient strength in the green (green) state to be able to withstand successfully handling and post-processing operations as such, that is to say without a cookie stage (first firing) is required. Therefore, it can be enamelled and baked in a ceramic product cast as is, without cookie stage. If necessary, it can be enamelled and cooked after having colored said cast product, then

  make it undergo enameling cooking and decoration.

  The compositions according to the invention can give excellent

  These results not only occur when they are formed by pulp processes, but also when they are formed by extrusion processes, sizing processes, gelling processes, filming using the potter's wheel, etc. As mentioned above, the present invention can produce the following excellent effects: 1) The cooking stage can be suppressed

biscuit (or first cooking).

  2) The post-processing operations are easy.

  3) When using a pottery paste, one

  can remove or reduce the constituent clay.

  4) It makes it possible to apply the paste molding (slip casting) to ceramic materials, which

  makes it possible to obtain new ceramic products of

rations quite complicated.

2 5 7 1 7 1 6

  It provides cast products with

  improved green (green) resistance.

  To obtain a new ceramic product of desired complicated configurations according to the present invention, it is necessary to use a treatment method which comprises the successive steps A to E above. Among these successive stages, stages A and B are exactly the same as the corresponding stages described above with regard to ceramic materials. Therefore, it is stage C and the stages that follow it that will be described

in detail in the following.

  Thus, two or more new cast ceramic products formed by steps A and B, a joining agent in step C, are applied to the surfaces to be joined. In step D, they are combined into one product. unitary cast. If the bonding agent used in Step C is different from those used to carry out the present invention, the resistance

  the junction will be insufficient even after cooking.

  The product obtained would thus separate at the level of the

in use.

  In the context of the invention, the bonding agent contains a ceramic material and an emulsion of resins,

as main constituents.

  As examples of ceramic material constituting the joining agent, it is appropriate to mention the same new ceramic materials as those described above. Any of these new ceramic materials can be used. Although it is not absolutely necessary to use the same new ceramic material as that used in Stage A, it is preferred to use the same

  new ceramic material. Ceramic materials include

  in general, fine ceramic materials pre-

  grain size down to about 100 A (angstroms) and relatively

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  coarse grains with particle size

  amount to about 5 mm. In the case of these ceramics

  coarse, it is better to use them after

  have them crushed to a desired particle size.

  As examples of resin emulsions representing the other constituent of the joining agent, it is appropriate to mention the same resin emulsions as those mentioned above. Any of these emulsions can be used. It is not absolutely necessary to use the same resin emulsion as used in Step A, but again, an acrylic resin emulsion is preferred. It is also possible to use in combination two or more emulsions of resins of different natures. The joining agent contains a ceramic material

  and an emulsion of resins, as previously indicated.

  Before its application, it can be dispersed in a dispersion medium, if desired. Water is preferred, as

dispersion medium.

  The proportion of the resin emulsion to be added to the ceramic material may vary depending on the type of ceramic material, the type of resin, the type of cast ceramic prosthesis to be produced, etc. Therefore, it can not be specified in a very general way. However, it is generally advisable to add the resin emulsion

  a proportion of about 0.1 to 20 parts by weight of

  solids in the emulsion per 100 parts by weight of the

dry ceramic material.

  The preferred proportion of the ceramic material in the bonding agent may be from 20 to 90 parts by weight per 100 parts by weight of the bonding agent. The bonding agent thus obtained is applied to the surfaces to be joined to cast products obtained by stages A and B. It is preferred here to wet the surfaces at 17 17 16

  assemble cast products with the same dispersion medium

  which is incorporated in the bonding agent, before applying the bonding agent to them. If the surfaces to be bonded with the dispersion medium are not wetted, migration of the dispersion medium from the bonding agent to the cast products is caused. As a result, the final product to be obtained after cooking will have a lower adhesion. The bonding agent can be applied to both surfaces to be joined. There is however no problem or disadvantage to apply it to one of the surfaces to be assembled. Although there is no particular restriction on the amount of bonding agent to be applied, it can generally be done in a layer thickness of 0.1 mm to 5 mm. It is preferred to apply the bonding agent to the surfaces as evenly as possible. As a method of application, it can be applied in the usual manner, for example, with the spatula, or in a similar manner. The cast products are assembled, to the surfaces to be assembled of which is

  applied the splicing agent during stage D.

  then kills the cooking during the stage E, under conditions consistent with the ceramic material used, which provides the desired ceramic product. With regard to the stage E cooking conditions, the cooking temperature may be, in general, between 1000 and 2500 C, the cooking time may be in the usual range between 0.1 and 200 hours and the cooking atmosphere is normally air. However, there is no problem or disadvantage in using an inert gas such as nitrogen as the cooking atmosphere. Unlike conventional porcelain, new ceramic products are difficult to form as previously mentioned. Indeed, because of

  lack of suitable binder for new ceramic products.

  The products formed are not strong before cooking.

  It goes without saying that it was virtually impossible, with prior art techniques, to join two or more cast products, and then to bake cast products together, when taking into account various properties required for new products. ceramics, at the beginning of which was the mechanical strength.

  With the present invention, it has become practical

  it is possible to produce products cast

  improved green (green) state by dough molding, by incorporating an emulsion of resins into a

  slip containing a ceramic material as a constituent

  killing principal. Furthermore, by assembling two or more cast products with a specific bonding agent, it has become practically possible also to obtain, after firing, a new ceramic product of complicated configuration without this being to the detriment of the various properties of

  head of which we find the mechanical strength.

  When the dough molding (slip casting) is performed on the ceramic product forming composition according to the invention in a plaster mold, the mold release characteristics of the composition are

  essential characteristics determining the success or the

  pulp molding. Here, the term "mold release characteristics" refers to features of the type indicating whether a cast product can easily be removed from the corresponding gypsum mold or the like, and whether the molded product has nicks or deformation occurring

  during its demolding of the corresponding mold. For good demoulding characteristics

  ge, it is considered that it is necessary that the adhesion between a mold and the cast product corresponding thereto is low, the strength or resistance of the molded product, during its demolding, that is to say its wet strength, sufficiently high, and that the cast product has dry strength or fastness to withstand handling during finishing and transport operations, after demolding and subsequent drying .

  The demolding characteristics are in correlation with

  with the following two parameters. The first parameter is the green (green) strength of a molded product. The second parameter is adhesion at the interface between the mold and the ceramic material, ie the force required to separate the molded product from the surface of the mold (which will be called, in the after,

  "demolding resistance"). It is known that this resistance

  this at demolding varies considerably, depending on the type and proportion of deflocculation agent to be added to the dough. It is also known that the wall thickness of a plaster mold decreases to a greater extent, that is to say that the plaster mold undergoes a greater deterioration during

  demoulding of the corresponding cast product, when

  a slip with better release characteristics. In other words, the service life of a plaster mold decreases when the release characteristics of a slip improve. One reason for this trend may be that the deflocculation agent present in the slip reacts on the plaster mold at their interface and that the reaction product acts to reduce adhesion at the interface, but the surface layer of the plaster mold is destroyed

by the reaction.

  To solve the above problem, it has been proposed to incorporate wax emulsions in pottery pastes and ceramic materials. The use of such emulsions, however, is still insufficient as

  method of solving the aforementioned problem.

  To find a way to improve the resistance

  in the green (green) state of the cast products,

  a whole series of researches, including the addition of -

  water-soluble high molecular weight substances such as soluble high molecular weight substances

  in natural water, for example gum acacia and algae.

  Sodium Nate, semi-synthetic water-soluble high molecular weight substances, for example

  methylcellulose, hydroxyethylcellulose, hydroxypropyl-

  methylcellulose and carboxymethylcellulose, and synthetic water-soluble high molecular weight substances, for example polyvinyl alcohol and water-soluble acrylic polymers. Because a high molecular weight substance soluble in water is

  caused by the movement of water by its inherent nature

  In this process, the water-soluble high molecular weight substance, along with the water, enters the surface layer of a plaster mold when making the paste molding. Thus, the surface of the mold deteriorates, or the fine porous structure of the mold surface becomes lumpy. For these reasons, the duration of use of the

mold is reduced.

  During the dough molding or drying stage of the subsequent cast product, water passes to the surface of the cast product. So, water is absorbed,

  of the surface of the product cast in the plaster mold cor-

  respondent when making the dough molding. During drying, water is allowed to vaporize which evaporates from the surface of the cast product. Because the water-soluble high molecular weight substance is moving together with water as previously indicated, the water-soluble high molecular weight substance accumulates locally in the vicinity of the water. the surface of the cast product, while there is almost no water-soluble high molecular weight substance present in the center region of the cast product. As a result, the cast product cures only near its surface. Because of this non-uniform resistance, there was a possibility that the ceramic products might cause stress and warping or cracking could occur after

C 7,, 11 I_

cooking or sintering.

  It has however been found that by using an aqueous emulsion of a specific copolymer, comprising: A) 0.1 to 15% by weight of a carboxylated monomer unit, and / or B) 0.1 to 5% by weight of a a substituted or unsubstituted carbamoyl monomeric unit represented by the following general formula:

H2C = C R2

2 CN /

O

O R3

  in which R and R2 may be the same or different

1 2

  and represent separately a hydrogen atom or a methyl group, and R3 represents a hydrogen atom, an alkyl (or alkyl) group having 1 to 4 carbon atoms,

  or a hydroxymethylene or alkoxymethylene group

  the following general formula:

CH2OR4

  wherein R4 denotes a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; and C) 85 to 99.9% by weight of one or more other monomeric units copolymerizable with the monomer indicated in A) and / or B) above, as resin emulsion (s), during the preparation of a composition for forming ceramic products, suitable for use in dough molding, by adding the resin emulsion (s) to a slip containing a paste

  for pottery or a ceramic material as the main con-

  According to the present invention, the use of the aqueous resin emulsion could not only improve the mechanical strength of the casting, but also, surprisingly, improve its demolding characteristics and extend the service life of the casting. plaster mold. As preferred examples of carboxylated monomer (hereinafter referred to as "A monomer") being

  monomer units constituting the specific specific copolymer

  examples are acrylic acid, methacrylic acid, itaconic acid, crotonic acid, fumaric acid and maleic acid, and monoalkyl esters of itaconic acid and maleic acid. Of the units constituting the copolymer, the proportion of this monomer may be from 0.1 to 15% by weight or, preferably, from 2 to 10% by weight. If its proportion exceeds 15% by weight, the viscosity of the slip becomes too high, its fluidity is reduced and it can not form good cast products, when the aqueous emulsion obtained is

  added to the slip. On the other hand, lower proportions

  0.1% by weight do not allow the formation of

  cast products with green (green) strength is sufficient

  health. As preferred examples of substituted or unsubstituted carbamoyl monomer (hereinafter referred to as "monomer B") forming part of the monomer units constituting the abovementioned specific copolymer, mention may be made of acrylic amide, methacrylic amide and dimethyl amide. (meth) acrylic, amide N-methylol (meth) acrylic, amide

  methoxymethylol (meth) acrylic amide butoxymethylol

  (meth) acrylic, and similar amides. Among the units constituting the copolymer, the proportion of this monomer may be from 0.1 to 5% by weight or, preferably, from 0.5 to 4% by weight. If its proportion exceeds 5% by weight, the viscosity of the slip becomes too high and its viscosity increases with time, which results in reduced fluidity, when the aqueous emulsion obtained is added to the slip. It becomes impossible to form good

  Stably cast products. If its proportion is

  than 0.1% by weight, on the other hand, it will be impossible

7 1 7 16

  to form cast products with resistance

  or solidity in the green (green) state sufficient.

  When the monomer A and the monomer B are used in combination as constituent monomer units of a copolymer, the total proportion of these two monomers must be from 0.1 to 15% by weight of the constituent monomers of the copolymer, and the proportions of the respective monomers must be included in the abovementioned intervals which

* correspond to them.

  As a monomer (hereinafter referred to as "monomer C") copolymerizable with monomer A and / or monomer B, a hydroxylated monomer may be used. Examples of such a hydroxylated monomer are 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, and the like. When such a monomer is used as the constituent unit in a proportion of 0.2 to 10% by weight in the copolymer, the viscosity of the slip decreases and a good fluidity can be obtained.

  and good long-term viscosity stability (that is,

  to say that the viscosity does not increase, even when the

  time passes), adding the copolymer obtained to the slurry

  born. If it is used in proportions greater than 10% by weight, the demolding characteristics degrade

  during the dough molding and the plaster mold becomes log

  This reduces the life of the mold. We

  therefore prefers not to use monomer C in

  outside the range indicated above.

  As monomer C, apart from the abovementioned compounds,

  it is possible to use, for example, acrylic esters

  such as methyl acrylate, ethyl acrylate,

  n-butyl acrylate, 2-ethylhexyl acrylate, acry-

  octyl late, methoxyethyl acrylate, butoxyethyl acrylate, cyclohexyl acrylate and acrylate

  furfuryl; methacrylic esters such as methacrylate

  methyl crylate, ethyl methacrylate, methacrylate

  Butyl crylate, methoxyethyl methacrylate, 1717

  ethoxyethyl methacrylate, butylboxy-methacrylate

  ethyl and benzyl methacrylate; aromatic monomers

  vinylic agents such as styrene, 1'-methyl-styrene and paramethylstyrene; vinyl esters such as vinyl acetate and vinyl propionate; nitriles such as acrylonitrile and methacrylonitrile; and, in addition, vinyl chloride, ethylene, butadiene, and

analogous compounds.

  The aqueous emulsion of the specific copolymer is an emulsion of a copolymer containing the monomer C as

  principal constituent ground, as mentioned above.

  ously. As examples of preferable aqueous emulsions, it is appropriate to mention an aqueous emulsion of a copolymer obtained by carrying out a copolymerization, in particular, using,

  as monomer C, an acrylic ester, a styrene mixture

  acrylic ester, a styrene-butadiene mixture, a mixture

  methyl-butadiene methacrylate or a styrene

  methyl methacrylate-butadiene.

  When a surfactant is incorporated in the aqueous emulsion of the specific copolymer, its proportion is preferably limited to less than 1.0% of the total weight of the monomers. The particle size of the emulsion polymer may be from 0.05 to 0.6 μm,

  the range of 0.1 to 0.25 μm being particularly preferred.

  If the proportion of surfactant exceeds 1% by weight, or if the particle size of the emulsion exceeds 0.6 μm, the viscosity of the slip decreases, but effects such as excellent release characteristics of the product. Casting obtained and a prolonged life of the plaster mold are not fully presented, when the aqueous emulsion obtained is added to the slip. If the particle size of the emulsion is less than 0.05 .mu.m, on the other hand, the slip containing the obtained aqueous emulsion which has been added thereto may have a

  higher viscosity and its fluidity can thus be reduced.

  The ceramic product forming composition prepared by adding the aqueous emulsion of the slip-specific copolymer containing a pottery paste or a ceramic material as the main component is extremely stable and has a low viscosity and a low viscosity.

  good fluidity; in other words, it presents an excellent

  slow ease of shaping. Molded or cast products

  obtained have excellent mechanical strength.

  Moreover, when this composition is used in the form of a slurry, the demolding characteristics are particularly improved, when the molding is done in paste form and, at the same time, the duration of use.

  plaster slip casting mold can be

to a significant extent.

  The excellent effects described previously of the

  composition using the aqueous emulsion of the particular copolymer

  can be attributed to the fact that in the

  In this way, a kind of interaction occurs between the mineral particles of the pottery paste or the ceramic material and the copolymer droplets of the aqueous emulsion and, as a result, the copolymer particles are adsorbed onto the mineral particles. This is suggested

by the two following phenomena.

  With respect to the first phenomenon, water is added to the above composition, i.e. the slip, to dilute its solids concentration to about 50-70%. When the slurry thus diluted is allowed to stand for 3 days to 1 week, a layer of clear, clear water is formed which floats. The water layer contains almost no emulsion particles. It is assumed that the polymer particles of the emulsion have been adsorbed on the mineral particles and thus have been precipitated together with the mineral particles. On the other hand, a similar slip is prepared by means of an aqueous emulsion of a copolymer other than

25717-16

  the aqueous emulsion of the specific copolymer, ie an aqueous emulsion of a homopolymer or a copolymer which does not contain the monomer A and / or the monomer B as the constituent monomer (s) constituent (s). A similar test is carried out on the slip. A layer of water that floats

  forming when the slip is allowed to settle, is

  ble and not limpid. It still contains a proportion

  significant amount of polymer particles from the emulsion.

  With respect to the second phenomenon, the composition using the aqueous emulsion of the specific copolymer is compressed in a press filter. It is virtually colorless and limpid water that is expressed. The water thus obtained

  does not contain polymer particles of the emulsion.

  On the other hand, a similar slip is prepared by means of an aqueous emulsion of a copolymer other than the aqueous emulsion of the specific copolymer, that is to say an aqueous emulsion of a homopolymer or a copolymer which does not contain

  monomer A and / or monomer B as the single unitary unit (s)

  constituent mother (s). When the slip is compressed in the press filter, it is a cloudy and not clear water,

  containing a significant proportion of polymer particles

  re of the emulsion that is expressed. -

  As suggested by the phenomena just described, carboxyl groups and / or alkoxymethylene groups contained in polymer particles

  can be a cause of the particle adsorption phenomenon.

  the mechanism on which the interaction induced between the mineral particles of the pottery paste or the ceramic material and the

  droplets of the specific copolymer of the aqueous emulsion.

  The invention will now be described specifically with the following nonlimiting examples. It goes without saying that these examples illustrate only a small part of the present invention. In these examples, all parts

2 5 7 1 7 1 6

  and all percentages are by weight unless

contrary specification.

EXAMPLE 1.-

  To a pottery paste of low clay content (product of Marui Tohryo Kabushiki Kaisha; Paste Special Quality), as a paste for pottery, nap glass (potassium orthosilicate) n 1 is added in a proportion of 0.41% reported to the dry solids of the pulp, then water is added, mixing and stirring to obtain a slurry having a solids content of 68.4%. We add respectively to

  Portions of the slip of resin emulsions A (emulsified

  acrylic resin resin comprising a copolymer obtained from styrene and 2-ethylhexyl acrylate as the main monomer component; solids content: 43%), B (acrylic resin emulsion modified with

  carboxyl containing a copolymer obtained from styrene

  and 2-ethylhexyl acrylate as a monomeric component

  re main; solid content: 43%), C (synthetic rubber emulsion containing a copolymer obtained from

  from styrene, methyl methacrylate and butadiene

  not as main monomer component; solids content: 43%) and D (vinyl acetate resin emulsion containing polyvinyl acetate as a main constituent, solids content: 43%), as shown in Table 1. the mixtures are agitated

  resulting to obtain homogeneous slip.

  The slips are respectively poured into plaster molds 90 mm long, 20 mm wide and 5 mm thick each. After letting the slips rest

  until accumulations of ceramic particles accumulate

  On the surfaces of the corresponding molds, the products thus cast are demolded from the plaster molds. Then, they are dried at room temperature and at 110 ° C., respectively, to obtain cast products having the dry flexural strength indicated in Table 1. The cast products are then slurried (molded into paste) in order to obtain excellent ceramic products. In this connection, flexural strength is measured by means of the "Tensilon S UTM-III-500" trademark, manufactured by Toyo-Baldwin Co., Ltd.).

TABLE 1.

  Type of emulsion Proportion added (%) Flexural strength of (emulsion / poles of lasec (kgf / cm?)

  100% dry paste resin) Drying at Drying.

Temp. 1100C ambient

_ {1 22 21

A 3 42 44

- 5 55 57

B 5 50 58

C 3 35 33

D 3 18 20

No emul- 0 12 13

added ...

  In addition, a slurry casting (paste molding) is carried out on a portion of the slurry without adding a resin emulsion. The baked product obtained is baked with a biscuit at 800 ° C. The bending resistance of the product having undergone biscuit baking

is 36 kgf / cm2.

EXAMPLE 2

  To a paste containing clay (product of Marui Tohryo Kabushiki Kaisha; Paste No. 30), as a paste for pottery, is added n.1 water glass in a proportion of 0.26%, based on the dry solids of the dough. then water is added by mixing and stirring to obtain a slurry with a solids content of 69.1%. The resin emulsion A used in Example 1, as shown in Table 2, is respectively added to portions of the slurry to obtain castings in the same manner as in Example 1. They are dried

  then to obtain cast products with resistance

  dry bending strength shown in Table 2. It is possible to obtain excellent ceramic products by

baking cast products.

TABLE 2.

_.

  ype of emul- Proportion added (%) Resistance to the flexion of (emulsion / weight of dry pulp (kf / cm2) resins absolutely dry) Drying on Drying at temp. 110 ° C ambient

1 25 24

A 3 46 45

54 56

No emul- 0 17 17

Lisln aj4outéE .....

  In addition, a portion of the slurry is slurried without adding a resin emulsion. The resulting cast product is baked with a biscuit at 800 ° C. The flexural strength of the biscuit baked product is

41 kgf / cm2.

EXAMPLE 3

  Five kilograms of powdered alumina ("A-16 SG", trademark of Aluminum Company of America) and 5 kg of powdered alumina ("A32", registered trademark of Nippon Light Metal Co.) were weighed. , Ltd), to obtain 10 kg of alumina powder mixture. We add to

  mixture of alumina powders 60 g of a deflocculating agent

  ("Seruna D-305", trademark of Chukyo Yushi Kabushiki Kaisha) and water. The resulting mixture is then stirred to obtain a slurry having a

  solids content of 81.4%.

  At portions of the slurry,

  resin emulsions A, B, C and D, used in Example 1, and an emulsion of resin E (acrylic resin emulsion containing a polymer obtained from n-butyl methacrylate, as main monomer component; solids: 43%), as shown in Table 3. Following the procedures of Example 1, cast products were obtained and then dried to obtain cast products having the dry flexural strength indicated on Table 3. Excellent ceramic products can be obtained by cooking the products

cast above.-

TABLE 3.

  Type of emulsion - Proportion added (%) Resistance to flexion at the rate of (emulsion / dry weight (kgf / cm2) resin absolutely dry) Drying at 110 ° C

A 3 39

1 31

B 3 58

84

C 3 41

D 3 45

B 3 86

No fmul- 1

lion adds! -

EXAMPLE 4.-

  To silica (siliceous stone imported from the Republic of China), a deflocculation agent ("Seruna D-305", registered trademark, product of Chukyo Yushi Kabushiki Kaisha) is added, in a proportion of 0.6% reported

1 7 16

  to dry solids of the ceramic material. We add

  The mixture is then added to the resulting mixture of water and then stirred to obtain a slurry having a solids content of 68.9%. Slab emulsions B, C and D, used in Example 1, respectively, are added to portions of the slurry as shown in Table 4.

  the procedures of Example 1, we obtain cast products.

  They are then dried to obtain cast products with

  both the flexural strength to dry indicated on the

table 4.

TABLE IV

  Type of 4mu] Proportion added (%) Resistance & flexion of (emulsion / dry pulp weight (kgf / cm2) strongly dry resin) ___ _ _ Drying at 1000C '

15. _

B 3 47

C 3 29

D 3 21

  No added dose J 08

EXAMPLE 5

  To 10 kg of zirconia ("TZ-EY", registered trademark of Toyo Soda Mfg. Co., Ltd.) was added 200 g of a deflocculating agent ("Seruna D-305", registered trademark produced by Yushi Kabushiki Kaisha) and water, to obtain a slurry having a solids content of 71.4%. The resin emulsions A and D, used in Example 1, are respectively added to portions of the slurry as shown in Table 5. Following the

  procedures of Example 1, we obtain cast products.

  They are then dried to obtain cast products with

  both the dry flexural strength shown in Table 5. Excellent ceramic products can be obtained

by cooking the cast products.

TABLE 5.

  Type of emulsion Proportion added (%) Resistance to flexion-sion (emulsion / weight of dry r (kgf / cm2) resin paste absolutely dry) Drying at 110 ° C

A 3 44

D 3 42

No added Sion 22

EXAMPLE 6

  To 1000 g of silicon carbide powder in the form ("Betarundum Ultrafine", registered trademark of Ibiden Co., Ltd.), 3 g of boron (product of Mitsuwa Kagaku Kabushiki Kaisha), 3 g of a deflocculation agent ("SMA 1440H", trade name of ARCO Chemical Company, ammonium salt of a styrenic monoester of maleic acid copolymer), 10 g of a 70% aqueous solution of monoethylamine (product of Kishida Chemical Co., Ltd.) and water, to obtain a slip having a content

in solids of 65%.

  The resin emulsion A is added to the slip,

  used in Example 1, as shown in Table 6.

  By following the procedures of Example 1, a cast product is obtained. It is dried to obtain a cast product having the flexural strength indicated on the

table 6.

f 71 7 1

TABLE 6.

  Type of emul- Proportion added (%) Resistance to flexion at the die (emulsion / dry weight (kgf / cm2) resin paste absolutely dry) Drying at 110 ° C

A 3 20

No emul-

lsion added.

EXAMPLE 7

  A cast product is obtained in the same way as in Example 6 except that, during the preparation of a

  100 g of a phenol resin emulsion are added

  that (molar proportion formaldehyde - phenol: 2, solids content: 50%). Subsequently, it is sintered at 2.120 ° C. to obtain a sintered product having a specific weight.

  equivalent to 98% of its theoretical specific weight.

EXAMPLE 8

  1000 g of colcotar (or red from England) ("NSK-500", registered trademark, product of Morishita Bengara

  Kogyo Kabushiki Kaisha), 20 g of an agent of deflo-

  ("SN Dispersant 5.020", registered trademark;

  Sun Nopco Ltd) and water. The resultant mixture is then stirred

  both to obtain a slurry having a content of

70% solids.

  Portions of the slip are then added to the resin emulsions A, C and D used in Example 1, as shown in Table 7. Following the procedures of Example 1, cast products are obtained. We dry them

  then to obtain cast products with resistance

  dry bending strength shown in Table 7.

2 5 7'1 7 106

TABLE 7.

  Type of emulsion - Proportion added ') Flexural strength (dry) (emulsion / dry weight (kgf / cm2) resin paste absolutely dry) drying at 110C

A 3 65

C 3 70

D 364

  No emulsion added Following the same preparation procedure as that described in Example 3, a slip is obtained.

  having a solids content of 81.4% using

  the same raw materials as those described in

Example 3. To the slip is added an emulsion of acrylic resin F.prepared

  according to the method of preparation described below, in a proportion of 3% by weight relative to the dry ceramic material. The resulting mixture is stirred to obtain a homogeneous slip. This slip is poured into a plaster mold, then left to rest for half an hour, so that a deposit of ceramic particles is deposited on the wall of the mold. The cast product resulting from the mold is then demolded and dried at 110 ° C. for one hour, so that a green cast product is obtained for a cup section. The cast product has a resistance to the state

sufficient vintage.

  We also obtain, in the same way, a

  raw cast product for the corresponding loop section.

  Each of the cup and bail sections is wetted with water at their mutual joining surfaces. Immediately thereafter, the above slip is applied to the surfaces with a spatula. We assemble them then. Then, the product thus assembled was dried at 110 ° C. for 30 minutes and then cooked at 1700 ° C. for 4 hours. We get a cup to

7 1 7 16

  coffee based on alumina. The adhesion between the handle section and the cup section of this coffee cup is strong. She

  has an extremely high impact resistance.

  Preparation of the Acrylic Resin Emulsion F. In a 5-neck vial equipped with a vane rack, thermometer, reflux condenser, dropping funnel and supply line of nitrogen, 500 parts of water and 4 parts of anionic emulsifier are placed. The internal temperature of the system is raised to 80 ° C., to which 5 parts of potassium persulfate are added. The contents are shaken until potassium persulfate

dissolves.

  Then, a liquid mixture comprising 240 parts of methyl methacrylate, 740 parts of ethyl acrylate, 20 parts of hydroxyethyl methacrylate, 1 part of an anionic emulsifier and 500 parts of water is added dropwise thereto. 4 hours through the dropping funnel. After completion of the dropwise addition, the contents are maintained at a temperature of 80 ° C. for a further

  3 hours. It is then cooled. When the temperature

  did not go below 30WC, ammonia is added

  to adjust the pH to 9. Then add water to obtain

  the acrylic resin emulsion with a

solids of 42%.

EXAMPLE OF COMPARISON 1.

  It is desired to obtain a cup in the same manner as in Example 9, except that a slurry without deflocculation agent or organic binder is added. The cup separates at the junction of its components. We can not obtain

baked product satisfactory.

EXAMPLE 10

  By following the same preparation method as that described in Example 4, a slip having a solids content of 68.9% is obtained using the

  same raw materials as those described in Example 4.

  To the slip, an acrylic resin emulsion G prepared according to the method of preparation described below, in an amount of 3%, is added to the absolutely dry ceramic material. The resulting mixture is stirred to obtain a homogeneous slip. Then, products are poured in the same way as in Example 9. They are assembled and then cooked. A coffee cup is obtained which has a strong adhesion between its handle section and its cup section and has a shock resistance

extremely high.

  Preparation of the emulsion of acrylic resin G.

  Following the same procedures as those

  during the preparation of the acrylic resin emulsion

  Except that the composition of the 500-mer monomers is changed.

  of styrene and 500 parts of 2-ethylhexyl acrylate, the acrylic resin emulsion G is obtained.

EXAMPLE 11

  A coffee cup is obtained in the same manner as in Example 10, except that a resin-containing synthetic rubber emulsion H prepared by the preparation method described below is used as a resin emulsion. This coffee cup has a strong bond between its handle section and its cup section, as well as a

  extremely high impact resistance.

  Preparation of Emulsion H of Synthetic Rubber Containing Resin H. In a stainless steel pressure polymerization vessel equipped with a paddle stirrer and a thermometer, 1000 parts of water, 10 parts of sodium dodecylbenzenesulfonate, 7 parts of potassium persulfate, 480 parts of styrene, 200 parts of methyl methacrylate, 300 parts of butadiene and 20 parts of acrylic acid. After keeping the contents at 70 ° C. for 12 hours, it is cooled. When the internal temperature has dropped below 30 C, cootothalammonium for

7 17 I 6

  adjust the pH to 9, then add water to obtain the emulsion H of synthetic rubber containing a resin,

  having a solids content of 42%.

EXAMPLE 12

  By following the same preparation method as that described in Example 5, a slip having a solids content of 71.4% is obtained, using the same raw materials as those described.

in example 5.

  To this slurry, the acrylic resin emulsion F is added in a proportion of 3%, based on the absolutely dry ceramic material. The resulting mixture is stirred to obtain a homogeneous slip. Then we

  gets products cast in the same way as in the example

  9. They are then assembled and cooked at 1,550 C

  3 hours. A coffee cup having a strong adhesion between its handle section and its cup section is obtained, and having an extremely high impact strength.

EXAMPLE 13

  By following the same preparation method as that described in Example 6, a slip is obtained.

  with a solids content of 65% using

  the same raw materials as those described in

example 6.

  To the slip, the acrylic resin emulsion G is added in a proportion of 3% relative to the absolutely dry ceramic material and 100 g of a phenolic resin emulsion (formaldehyde-phenol molar proportion: 2 solids content: 50%). The resulting mixture is stirred to obtain a homogeneous slip: Next,

  gets products cast in the same way as in the example

  9. They are assembled and then calcined at 2,150 ° C.

  minutes. A coffee cup with an adhesive is obtained

  high frequency between its handle section and its cup section

  and having an extremely high impact resistance.

* EXAMPLE 14.-

  Following the same preparation procedure as that described in Example 1, a slurry having a solids content of 68.4% is obtained using the same raw materials as those described in Example 1. It is added respectively, to portions of the

  slip, aqueous emulsions (solids content

  43%) of copolymers which contain, as constituent units, the monomers shown in Tables 8 (1) to 8 (3) in the respective proportions also indicated therein. The resulting mixtures are stirred to obtain

homogeneous slips.

  The slips are respectively poured into plaster molds, each of which is 0.0 mm long, 20 mm wide.

  and 5 mm thick. After leaving

  ceramic particles accumulate on the walls of the molds cor-

  Corresponding, the molded products resulting from the molds corresponding to them are demolded. During the demolding of the cast products, each of the cast products is examined to see whether or not it has good demolding characteristics and whether or not the cast product thus demolded has good shape stability characteristics (that is to say, 'nicks are formed or deformed). After allowing them to rest at room temperature to dry, their strength is measured. With regard to their strength, it is their flexural strength that is measured using the Tensilon UTM-III-500 (trademark, manufactured by Toyo-Baldwin Co., Ltd.). The cast products thus obtained are then baked to obtain ceramic products in the form of ceramic products obtained respectively from cast products originating from compositions prepared by adding aqueous emulsions of copolymers in which the proportions of their respective monomers indicated on table 8 satisfy

257 17 16

  corresponding proportional intervals indicated in

  pages 20 and 21 of the present application, the ceramic products

These are all extraordinary.

  As a method of assessing the duration of use

  For each plaster mold, the duration of use is estimated by means of the 5-level rating system based on the upper limit of the number of operations.

  successful dough molding for the corresponding slip.

Excellent: 100 times and more.

Good: 70 to 99 times.

Acceptable: 40 to 69 times.

Poor: 20 to 39 times.

Unacceptable: 19 times and less.

  For each evaluation, the upper limit of the number of successful dough operations is determined

  while taking into consideration the characteristics

  demoulding products cast during mold release, the shape stability characteristics of

  products cast after demolding, and the degree of roughness

  the surface of the plaster mold after demolding.

  In this respect, the characteristics are visually determined.

  shape stability, depending on whether the cast products -

  have nicks, deformation, etc., appearing

  possibly during their demolding of the corresponding molds.

  The results of the evaluation are summarized in Tables 9 (1) to 9 (3), where A indicates examples using aqueous emulsions of specific copolymers.

  previously described, while B indicates examples

  reading aqueous emulsions of copolymers which do not correspond to the ranges of proportions of monomers described

  previously. In Table 8, the proportion of surfactant

  The active ingredient contained in each aqueous emulsion added to the alkalinity is co-expressed in terms of 100 parts by weight of the total amount of monomers used to obtain

  the corresponding copolymer. It also indicates the size

  average droplet size of each emulsion.

Table 8 (1)

B A B B A B A

  (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) )

  Methacrylic acid O 0 007 0.2 2 5 10 14 16 5 7 Acrylic acid 5 0 0.07 0r2 1 4 6 n Methacrylic acid 007 2 1 4 6

2 3

  O Acrylic Amide N-methylol-3 Acrylic Amide w Hydroxyethyl methacrylate w Acrylate 2-acrylate 50 50 50 50 50 50 50 55 55 55 55 55 55 50 50 55 4 Ethylhexyl

o N-acrylate

  butyl U Ethyl methyl methacrylate 50 49p93 4918 48.0,45.0 40.0 3610 34; 0 45 44.93 44.8 44/0 41/0 39.0 43.0 42/0 35 Styrene Butadiene Proportion of agent surfactant 04 04 4 0.4 0> 40 0.40; 4 0.3 0.3 0.33 0.3 0.3 0.3 0J4 0.3 0.4 Granulo- dimension 0.20 0/20 0.20 0/18 1 0.18 0.8 0.20 0 , 20180,20 0,20 0,20 0,20 0,20 0,220 0/20

average metric (pn) ......._.

m 0%

Table 8 (2)

A A

  (18) (19) (20) (21) (22) (23) (24) (25) (26) (27) (28)

  Methacrylic Acid Acrylic Acid 5 S 5 5 5 5 5 5 5 5 5 Methacrylic Amide2 2 2 2 2 2 2 2 2 2 2 Acrylic Amide

N-methylol

  c crylic3 4 thacrylate Q) ngthacrlate0) 1072 1 5 10 12 0 'hydroxyethyl 0> 2 1 5 10 12

a crylate of 2-

  thylhexyl 50 50 50 50 50 50 50 0 n-butyl crylate 60 u tyrene6030 utadiene 42> 9 42 # 842> 0 38] 0331031,0 40 33 60 30

33 33 33

  % of ensio-active agent 014 0.4 0O4 0> 4 0.4 014 0> 4 013 013 0; 3 0.3 imension granulom16016016 016 016 016 average r (pU16016 16 016 m), 16016 16 18 0 L_

Table 8 (3)

A A

  (29) (30) (31) (32) (33) (34) (35) (36) (37) (38) (39) (40) (41) (42) (43) (44)

  Methacrylic acid 5 5 5 5 5 5 5 5 5 Acrylic acid 5 5 5 5 5 Methacrylic amide 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 Acrylic amide o

N-methylol amide

  acrylic hydroxyethyl methacrylate

0. Aaryry of 2-

  o orylaede2- 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 P thylhexyl n-butyl acrylate UO ethyl ethacrylate Styrene 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 Styrene Butadiene Proportion of surfactant 0.6 0t6 0, 606 6 0.6 016 0 6 0; 6 0/6 0 1 0> 2 0.5 0.8 1.0 1> 2 2 0 Average particle size ( 0.02 0.05 0.08 0.15 0.20 0.30 0 050 0.80 1.60 0.20 0.20 0> 20 0.20 0.20 0.20 0; 20 medium average ( jim) rol -4 oL

Table 9 (1)

  Characteristic- Characteristic- Resistance Duration of use

  mold ticks mold release bending stability to plaster shape seec (kg'fom (1) Poor Poor 35 Poor B Fair (2) Poor Poor 37 Acoeptable (3) Good Good 43 Good

(4) Good Good 45 Exellent.

A (5) Good Good 47 Excellent

(6) Good Good 44 Excellent -

  (7) Good Good 45 Fair B (8) Bad Poor 43 Unreasonable (9) Poor Mediocre 38 Poor B Fair (10) Poor Mediocrities 41. Fair (11) Good Good 43 Good A (12) Good Good 45Excellent (13) Good Good 47 Excellent, B (14) Poor Poor 37 Unacceptable

, -

  (15) Good Good 47 Excellent A (16) Good Good 45 Excellent (17) Good Good 46 Excellent

Table 9 '(2)

  Characteris- Characteristics- Resistance Duration of use

  ticking of ticks from the mold. mold release molding mold stiffness stability (kgf / cm2) plaster (18) Good Good 42 Excellent (19) Good Good 45 Excellent (20) Good Good 46 Excellent A (21) Good Good 44 Excellent (22) Good Good 43 Excellent (23) Poor relativemen 41 Poor good A (24) Good Good 47 Excellent (25) Good 43 Excellent (26) Good 40 Excellent '(27) Good 41 Exceliente: (27) Good Good 41 Excellent (28) Good Good 45 Excellent

Table 9.X 3)

  Characteris- Characteristics- Resistance Duration of use

  mold tick ticks demolding bending stability dry plaster shape (kgf / cm2) (29) Poor Good 49 Poor (30) Good Good 46 Acceptable (31) Good Good 44 Good (32) Good Good 43 excellent A (33) Good Good 44 excellent (34) Good Good 42 excellent (35) Good Good 40 good enough relatively 39 Fair (36) poor good 39 (37) Poor Mediocre 37 Poor (38) Good Good 43 excellent (39) Good Good 47 Excellent (40) Good Good 45 Excellent A (41) Good Good 43 Excellent (42) Good Good 41 Good (43) Fairly Relative 38 Fair (43) Meticulous ons38 Acceptable Poor Good <44) Poor Mediocre 35 Poor In the examples above, the aqueous emulsions described in Table 8 (3) are prepared by carrying out an emulsion polymerization on the reaction mixtures prepared using anionic surfactants in a reaction mixture. standard for emulsion polymerization. The size of the droplets of each emulsion is adjusted in the usual way, that is to say by adjusting the concentration of the surfactant corresponding to the beginning of the reaction.

of polymerization.

EXAMPLE 15

  Using "N 22 Paste" and "N 30 Paste" (both Marui Tohryo Kabushiki Kaisha products) and New Bone N 57 Paste and New 60 N Paste N 60 "(trademarks, both products of Yamaka Tohryo Kabushiki Kaisha" as pasta for

  pottery, "soluble glass N 1" is added in a proportion

  0.26% in relation to the dry solids of the

  pasta, then add more water. We shake

  The resultant mixtures were obtained to obtain slurries having a solids content of 69.1%. To each of the slips, the aqueous emulsion (solid content: 43%) having the composition given in (5) of Table 8 (1) of Example 14, is added in a proportion

  3%, based on the weight of the absolutely dry paste.

  Following the procedure of Example 14, cast products are obtained. They are evaluated in the same way as in

  Example 14. The results are shown in Table 10.

TABLE 10.

AT

(1) (2) (3) (4)

  Characteristics of uCharacteristics of Good Good Good demolding Characteristics-of Characteristics of Good Good Good Goodness of form Resistance to dry bending 4C 46 45 43 (kgf / cm2) Duration of use Duration of use excellent excellent excellent excellent of the mold plaster

  Notes: (1) "Paste No. 22" from Marui Tohryo K.K.

  (2) "Paste No. 30" by Marui Tohryo K.K.

  (3) Yamaka Tohryo K.K. "New Bone No. 57 Paste"

  (4) Yamaka Tohryo K.K. "New Bone Paste No. 60"

EXAMPLE 16.-

  By the same method of preparation as that described in Example 3, a slurry having a solids content of 81.4% is prepared, using the same raw materials as those described in Example 3. portions of the slip aqueous emulsions (solids content: 43%) of the compositions respectively indicated from (1) to (43) in Example 14, each in a proportion of 3% referred to the mixture of alumina powder absolutely dry. We perform

  on slushes the molding in paste (the casting of

  ne) in the same way as in Example 14. They are evaluated in the same way as in Example 14, except that in this example the bending resistance of

  each product cast after drying at 110 ° C, and it was indicated

  as dry bending strength. The results are shown in Tables 11 (1) to 11 (3), where A also denotes examples using aqueous emulsions of the specified copolymers described above, while B also denotes examples using aqueous emulsions of copolymers entering not in the ranges of proportions of monomers

previously described.

Table 11 (1)

  Characteris- Characteristics- Resistance Duration of use

  Tick ticks. mold release bending stability to plaster form ec (kgf / cm2) (1) Poor Poor 38 Poor B (2) Poor Poor 40 Fair (3) Good Good 48 excellent (4) Good Good 52 excellent A ( 5) Good Good 56 Excellent A (5) Good Good 56 Excellen

(6) Good Good 55 Good.

  (7) Good Good 50 Fair B (8) Poor Poor 46 Unacceptable (9) Poor Poor 36 Poor B (10) Poor Poor 38 Fair (11) Good Good 51 excellent A (12) Good Good 55 excellent (13) Good Good 57 Good B (14) Poor Poor 49 Unacceptable (15) Good Good 58 Excellent A (16) Good Good 56 Excellent (17) Good Good 57 Excellent (17 Good 57 Excellent

Table 11 (2)

  Characteristic- Characteristic- Resistance Duration of

  tick ticks of demoulding stability of Elexion dry mold shape (kgf / cm2) plaster (18) Good Good 55 excellent (19) Good Good 57 excellent (20) Good Good, 58 excellent A (21) Good Good 54 Excellent (22) Good Good 52 Good (23) Bad Poor 48 Poor A (24) Good Good 53 Excellent (25) Good. Good 56 Excellent (26) Good Good 53 Excellent A (27) Good Good 55 Excellent (28) Good Good 57 Excellent

2 '1 6

Table 11 (3)

  Characteris- Characteristics- Resistance Duration of use

  ticks ticking mold demoulding stability flexing plaster dry form _., _ __ ,, _ _ _ _ (kgf / cmi) (29) Poor Good 53 Inaccapptable (30) Good Good 54 Acceptable (31 ) Good Good 52 Good

(32) Good Good 55 excellen-

A (33) Good Good 58 excellent-

  (34) Good Good 57 Excellent (35) Good Good 52 Good (36) Good Poor 50 Poor

  (37) Mediocre Poor 47 Acceptable.

  (38) Good Good 53 excellent (39) Good Good 58 excellent (40) Good Good 56 excellent A (41) Good Good 53 excellent A (41) Good Good 53 excellent (42) enough Raativemen 51 Good mediocre good (43) Poor Poor 47 Poor (44) Poor Poor 45 Unacceptable

EXAMPLE 17

  Using silica (a siliceous stone imported from the Republic of China), zirconia ('TZ-3Y', trademark of Toyo Soda Mfg Co., Ltd.) and silicon carbide in the P form ( "Betarundum Ultrafine", registered trademark of Ibiden Co., Ltd.) as ceramic materials, slips suitable for use in dough molding are prepared as described below. aqueous emulsion (solids content: 43%) of the composition indicated in (5) of Example 14, in a

  proportion of 3%, referred to the dry ceramic material.

  The slip thus prepared is carried out in a paste molding (a slip casting) in the same way as in Example 16. The results of their evaluation, which is carried out in the same way as in Example 16, are

shown in Table 12.

  Process for the preparation of slip liquids for dough molding

  (a) Silica (siliceous stone imported from the Republic of China) To the silica (siliceous stone imported from the Republic of China is added a deflocculating agent ("Seruna D-305", registered trademark, product of Chukyo Yushi Kabushiki Kaisha), in a proportion of 0.6% relative to the dry solids of the ceramic material Water is also added The resulting mixture is stirred to obtain a slurry having a content of materials

68.9% solids.

(b) Zi rcon-.

  To 10 kg of zirconia ('TZ-3y', trademark of Toyo Soda Mfg Co., Ltd.) was added 200 g of a deflocculating agent ("Seruna D-305", registered trademark; of Yushi Kabushiki Kaisha Chukyo) and water The mixture is stirred to obtain a slurry

  having a solids content of 71.4%.

2 1 7 16

  (c) Silicon carbide in the form of 1000 g of silicon carbide in the p-form ("Betarundum Ultrafine", registered trademark of Ibiden Co., Ltd.) was added 3 g of boron (product of Mitsuwa Kagaku Kabushiki Kaisha), 5 g of a deflocculating agent ("SN Dispersant 5045", trademark of Sun Nopco Kabushiki Kaisha), 10 g of a 10% aqueous solution of monoethylamine (product of Kishida Chemical Co., Ltd.) and water. The resulting mixture is stirred to obtain a

  slip having a solids content of 65%.

TABLE 12.

AT

(a) (b) (c) -

  Characteristics of Good Good Release Molding Characteristics of Good Good Fitness of Shape 20. Resistance to bending. (kgf / cm 2): excellent excellent excellent dryness of the plaster mold As shown in Examples 14 to: -1-7, by making the paste molding (slip casting) on slip compositions added with aqueous emulsions of such specific copolymers, it is possible to obtain

  cast products with improved dry strength;

  SOE. Moreover, when demolding cast products

  molds that correspond to them, they have excellent

  slow demolding characteristics and excellent shape stability characteristics. It is thus possible to improve the production yield of cast products to a significant extent while increasing the duration

  of each plaster mold.It is therefore practically

  It is possible to produce excellent cast products with a high yield, producing them by dough molding (slip casting) according to the casting process.

(casting) according to the invention.

7O 1t 7 1

Claims (9)

  Ceramic product forming composition, characterized in that it is formed by a mixture of a resin emulsion with a slip which contains a pottery paste or a ceramic material as the main constituent. Ceramic product forming composition according to claim 1, characterized in that the emulsion   of resin is an aqueous emulsion of a copolymer comprising ing:   A) 0.1 to 15% by weight of a carbon monomer unit   xylated, and / or B) 0.1 to 5% by weight of a substituted or unsubstituted carbamoyl monomeric unit represented by the following general formula: R H2C = C R2 C-N He - .. R O 3   wherein R 1 and R 2 may be the same or different and independently represent a hydrogen atom or a methyl group, and R 3 represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a hydroxymethylene or alkoxymethylene group represented by the following general formula: CH2 OR   Wherein R4 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and C) 85 to 99.9% by weight of one or more other monomeric units copolymerizable with the specified monomer. in A) and / or B) previously.   3. Composition according to claim 2, characterized   in that at least one of the other monomers is a hydroxylated monomer.   4. Composition according to claim 2, characterized   in that the aqueous emulsion has a dimension   average droplet from 0.05 to 0.6> m.   Process for forming ceramic products, characterized in that a paste molding is carried out (one   slip casting) on the composition according to the 1.   Process for casting ceramic products, characterized in that a paste molding is carried out (a   slip casting) on the composition according to the tion 2.   7. A process for forming ceramic products, characterized in that the composition according to claim 1 is subjected to a calibration, gelling or   shaping using the potter's wheel (turning).   8. A process for forming ceramic products, characterized in that the composition according to claim 2 is subjected to a calibration, gelling or   shaping by means of the potter's wheel (turning) ..   9. A method of treating a ceramic product, cast, characterized in that it comprises the following successive stages: a) A resin emulsion is mixed with a slip which contains a ceramic material as a main constituent, so as to prepare a slip composition; b) Two or more cast products are formed with the slip composition by a paste-molding (or slip-casting) process, said cast products having the same or different configurations, so that said cast products comprise at least one set of matching surfaces to assemble; c) A bonding agent is applied which contains a ceramic material and a resin emulsion as   components of at least one of the concordance surfaces   cast products; D) The mating surfaces of the cast products are joined to join the cast products into a unit cast product; and   e) the unit cast product is cooked.