JP2016204507A - Clay composition and production method of clay composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve property of a clay composition.SOLUTION: In a first embodiment, a clay composition is provided which has transparency after being dried, and is produced by: forming a silica dispersion by mixing a non-ionic surfactant, a high-boiling point nonvolatile liquid insoluble to water, and silica; then, mixing the silica dispersion and a polyvinyl acetate emulsion. In a second embodiment, a clay composition is provided which is identical to the clay composition in the first embodiment except that after forming the silica dispersion by mixing an anionic surfactant, water, and silica, the silica dispersion and the polyvinyl acetate emulsion are mixed for producing the clay composition. Since the polyvinyl acetate emulsion is used, adhesion of the clay composition can be enhanced. In addition, the silica is mixed with a dispersant in advance, so that dispersion property of the silica to the clay composition becomes preferable, and the occurrence of aggregate of the silica can be suppressed. Transparency is therefore improved by prevention of white spots, and crack can be prevented.SELECTED DRAWING: None

Description

  The present invention relates to a clay composition and a method for producing the clay composition, and more particularly to a clay composition having transparency after drying and a method for producing the same.

  Conventionally, synthetic clays used for handicrafts, school materials, toys, etc. are synthesized by combining natural clays, chemically synthesized glues, and various inorganic and organic fillers. Clay is used. Some of these clay compositions are slightly opaque but are basically opaque.

  In recent years, clay compositions having transparency have been developed. For example, products that mix a curing agent (catalyst) component with a transparent silicone resin material to form a crosslinked (three-dimensional) structure are now on the market. There are inconveniences that cannot be visually confirmed and that the silicone material itself is hard and difficult to form. Further, Patent Document 1 (Japanese Patent Laid-Open No. 2005-281634) and Patent Document 2 (Japanese Patent Laid-Open No. 2006-330412) disclose clay having transparency. Specifically, Patent Document 1 discloses a clay obtained by adding silica, cellulose ether, and polyvinylpyrrolidone to an ethylene-vinyl acetate copolymer. Patent Document 2 discloses a clay obtained by adding an ethylene-vinyl acetate copolymer to silica, cellulose ether, and polyethylene oxide or polyvinyl ether.

  Patent Document 3 (Japanese Patent Laid-Open No. 59-69466) discloses a technique for increasing the hardness after drying by adding a polyacrylate emulsion to natural clay.

Japanese Patent Laid-Open No. 2005-281743 Japanese Patent Laid-Open No. 2006-330412 JP 59-69466 A

  The inventor has conducted research and development on clay compositions. As will be described in detail later, the technology described in Patent Literature 1 and Patent Literature 2 and the technology in which the technology described in Patent Literature 3 is applied to the technology described in these technologies have been studied. Adhesion, transparency after drying An excellent clay composition could not be obtained in terms of deterioration of white (generation of white spots) and generation of cracks.

  Therefore, it is desired to develop a clay composition that has good adhesion and transparency and has a low incidence of cracking after drying.

  The present invention provides a clay composition having good adhesion in a clay composition, good transparency in the dried product, and having a low cracking rate, and a method for producing the same.

  The clay composition of the present invention has transparency after drying, and forms a silica dispersion by mixing a nonionic surfactant, a high-boiling non-volatile liquid insoluble in water, and silica. Then, it is manufactured by mixing the polyvinyl acetate emulsion and the silica dispersion. In addition, a silica dispersion is formed by mixing an anionic surfactant, water, and silica, and then a polyvinyl acetate emulsion and the silica dispersion are mixed. Thus, the adhesiveness of a clay composition can be improved by using a polyvinyl acetate emulsion. Further, by mixing silica with a dispersion medium in advance, the dispersibility of silica in the clay composition is improved, and the generation of silica aggregates can be suppressed. Thereby, transparency improves by prevention of a white spot and it can prevent a crack.

  According to the clay composition of the present invention, the properties of the clay composition can be improved. For example, the adhesiveness of the clay composition can be improved. Moreover, according to the manufacturing method of the clay composition of this invention, a clay composition with a favorable characteristic can be manufactured. For example, it is possible to provide a method for producing a clay composition having high transparency and less white spots and cracks in a dried clay composition.

(Consideration)
First, the matters studied by the present inventor will be described before the embodiments are described.

  In order to give transparency to the ethylene-vinyl acetate copolymer by adding silica, and to prevent deterioration of the properties of the clay due to the addition of silica, a clay composition in which polyvinyl pyrrolidone, polyvinyl alcohol and cellulose ether were added was studied ( Study technology 1). The clay composition obtained by this examination technique 1 had insufficient adhesiveness. Innumerable white spots (white spots) were confirmed after drying. Further, when the wall thickness was increased, cracks occurred after drying.

  Further, a case where a polyacrylic ester emulsion or a polyvinyl acetate emulsion was used instead of the ethylene-vinyl acetate copolymer was examined (Study Technique 2). In this case, transparency after drying could not be obtained due to high hermeticity and crystallinity of the resin and poor dispersibility of the powder component.

  The innumerable white spots and cracks are considered to be defects caused by poor dispersibility of the silica powder. For example, when silica powder is added at the final stage of mixing of the clay composition, the viscosity of the clay composition is too high, so that the dispersibility of the silica powder is lowered. Moreover, the heterogeneity of components occurs in the clay composition, and cracks are likely to occur after drying, for example, at locations where there are many volatile components.

  In order to improve the adhesion, white spot generation, and cracking of the clay composition obtained by the above examination technique 1, the causes will be examined in more detail.

  One of the causes is that an ethylene-vinyl acetate copolymer emulsion (an emulsion of ethylene-vinyl acetate copolymer) is used as a main binder in order to impart transparency, flexibility, and rubber texture. This is a cause of poor adhesion of the clay composition. Since the ethylene-vinyl acetate copolymer emulsion contains an ethylene unit on its resin structure, the adhesiveness is lower than that of a homopolymer emulsion of vinyl acetate.

  The other is that the dispersibility of the constituents of the clay composition, particularly the silica powder, is insufficient. This is a cause of white spots and cracks. In particular, ultrafine anhydrous silica powder is very likely to cause secondary aggregation due to its fineness. In particular, when ultrafine anhydrous silica powder is added at the final stage of the production of the clay composition and the hardness of the clay composition is adjusted, the ultrafine anhydrous silica component is agglomerated inside the clay composition. It is thought that there is a bias. The agglomerates that cannot be sufficiently dispersed here become white spots after drying, and the unevenness of the components causes the shrinkage of the shrinkage ratio of the clay during drying to cause cracks.

  Therefore, the present inventor first tried to improve the adhesion of the entire clay by changing the ethylene-acetic acid copolymer vinyl emulsion to a polyvinyl acetate emulsion in order to improve the adhesion. Thereby, it becomes possible to improve the adhesiveness of the clay composition which exhibits transparency. However, the viscosity of the clay composition increased with the adhesiveness, and the dispersion of the components of the clay composition (mainly ultrafine anhydrous silica powder), which was the cause of the second problem, was likely to occur. . It is extremely difficult to uniformly disperse ultrafine anhydrous silica powder having high water absorption in a highly viscous state. Therefore, before mixing the ultrafine anhydrous silica powder with polyvinyl acetate, it is preliminarily dispersed in a dispersion medium having a low viscosity (for example, water or a high boiling non-volatile liquid insoluble in water). This succeeded in improving the dispersibility of the ultrafine anhydrous silica powder contained in the clay composition and suppressing the occurrence of white spots and cracks.

  The material to be previously dispersed in the dispersion medium is not limited to ultrafine anhydrous silica powder. For example, components that are desired to be incorporated into the clay composition, such as a coloring agent, can be improved in the colorability of the clay composition by dispersing in advance in the dispersion medium.

  In carrying out this method, when kneading clay, kneading is performed under reduced pressure, thereby adjusting the hardness by evaporating moisture in the clay composition without increasing the temperature of the clay composition. succeeded in.

  Hereinafter, in the columns of “Embodiment” and “Example”, the considerations of the inventor will be described in more detail.

(Embodiment)
<Clay composition>
The clay composition of the present embodiment is composed of a mixture of a polyvinyl acetate emulsion and a silica dispersion. This silica dispersion is a mixture of a surfactant, a dispersion medium, and silica.

  More specifically, the clay composition of the present embodiment comprises (a) a binder, (b) a filler and an extender, (c) a thickener, (d) a surfactant, (e) a plasticizer, ( f) Antiseptic / antifungal agent, (g) Other additive aids, etc.

(A) Binder The binder is the main component of the clay composition. The solidification property, tackiness of the clay composition, and the mechanical strength of the dried clay composition vary greatly depending on the properties of the binder.

In the present embodiment, polyvinyl acetate is used as the binder. Polyvinyl acetate is a polymer (resin) of vinyl acetate (C ₄ H ₆ O ₂ , CH ₃ —CO—O—CH═CH ₂ , also referred to as vinyl acetate). More specifically, a polyvinyl acetate emulsion is used as the binder. The polyvinyl acetate emulsion is a mixture of a polymer of vinyl acetate and an emulsifier (for example, polyvinyl alcohol).

  As the binder, other binders may be used in combination as long as polyvinyl acetate is the main binder. For example, polyvinyl alcohol or polyvinyl pyrrolidone may be used in combination as a binder. As the polyvinyl alcohol, in addition to partially saponified polyvinyl alcohol, low saponified polyvinyl alcohol and completely saponified polyvinyl alcohol can be used regardless of the degree of saponification. A powder emulsion of polyvinyl acetate can also be used in combination. Polyvinyl acetate, polyvinyl alcohol, and polyvinyl pyrrolidone are suitable for use as a binder because of their high transparency and adhesiveness.

(B) Filler and extender The filler and extender are for bulking the clay composition and adjusting the viscosity. Moreover, when a clay composition dries, it needs to provide transparency. In the present embodiment, silica powder is used as the filler and the filler. Among silicas, it is preferable to use anhydrous silica. Moreover, as a primary particle diameter (diameter) of an anhydrous silica, it is preferable to use a 35 nm or less thing. In addition to silica powder, processed starch or the like may be used in combination as a filler and an extender.

(C) Thickener The thickener is a component that imparts viscosity to the clay composition and imparts releasability. As the thickener, for example, cellulose derivatives, acrylic derivatives, vinyl pyrrolidone derivatives and the like can be used.

  As the cellulose derivative, for example, water-soluble cellulose ether, carboxymethyl cellulose, methyl cellulose and the like can be used.

  As the acrylic acid derivative, for example, polyacrylamide, sodium polyacrylate, or the like can be used.

  As the vinyl pyrrolidone derivative, for example, polyvinyl pyrrolidone homopolymer can be used.

  Polyethylene oxide may also be used.

  The anhydrous silica powder and processed starch used as fillers and extenders also have some thickening.

(D) Surfactant A surfactant is a component that has the effect of reducing the surface tension of a liquid and reducing the interfacial tension between liquids and between a liquid and a solid, and increases the mixing effect of each component of clay. .

  As this surfactant, a nonionic surfactant or an anionic surfactant can be used.

  As the nonionic surfactant, for example, polyoxyethylene alkyl ether, glycerin fatty acid ester and the like can be used.

  As the anionic surfactant, for example, an alkyl sulfate ester salt, an alkyl benzene sulfonate, or the like can be used.

(E) Plasticizer The plasticizer is a component that imparts softness to the clay. In addition, when a filler such as silica is dispersed in advance, it can be used as a dispersion medium. For example, polyhydric alcohols such as glycerin, ethylene glycol, propylene glycol, adipates such as diisononyl adipate, phosphates such as triphenyl phosphate, citrates such as triethyl citrate, alkyl sulfonate phenyl esters Such as sulfonic acid esters, fatty acid (dibasic acid) esters, and the like can be used. As this fatty acid (dibasic acid) ester, it is preferable to use bis (butyldiglycol) adipate or the like. Although there is a concern about endocrine disrupting substances (so-called environmental hormones), phthalates such as dibutyl phthalate described in Patent Document 1 (Japanese Patent Application Laid-Open No. 2005-281634) can also be used. However, it is better not to use ingredients that are suspected of safety as much as possible. Liquid paraffin and silicone oil can also be used.

(F) Antiseptic and antifungal agent An antiseptic and antifungal agent is a component that imparts an antiseptic and antifungal effect to clay. As this antiseptic / fungal agent, for example, a bromopol-based antiseptic / fungal agent, an isothiazoline-based antiseptic / anti-fungal agent or the like can be used. The antiseptic / antifungal agent to be added is not particularly limited as long as it has safety and can obtain a sufficient antiseptic / antifungal effect.

(G) Other additive assistants Other additive assistants are components added to strengthen and improve the properties of clay, and various additives can be added depending on the properties of the target clay. . As other additive aids, for example, starch derivatives containing processed starch such as alpha starch, cellulose derivatives such as carboxymethyl cellulose, and colorants such as pigments and dyes may be used.

  Furthermore, as long as the clay composition is formed by mixing at least (a) a binder and (b) a filler and an extender, other materials ((c) to (g)) may be used as necessary. What is necessary is just to add suitably. Moreover, you may mix | blend materials (other addition adjuvant, other components) other than (c)-(g) suitably.

  When silica powder is used as the filler for the clay composition, it is preferable to use a binder having a refractive index similar to that of silica as the main component.

<Method for producing clay composition>
The manufacturing method of the clay composition of this Embodiment is demonstrated.

  (A) Silica powder and a dispersion medium are put into a powerful kneader. As the silica powder, an ultrafine anhydrous silica powder (particle size: 35 nm or less) is used. As the dispersion medium, water or a high boiling non-volatile liquid insoluble in water can be used. The high boiling point non-volatile liquid insoluble in water can be selected from (e) components used as a plasticizer. Further, water as a dispersion medium is a component other than the above (a) to (g), and plays a role as a dispersion medium when an anionic surfactant described later is used. However, the binder (a) such as a polyvinyl acetate emulsion may contain water (water).

  Next, a surfactant is charged. As the surfactant, an appropriate surfactant is selected depending on the dispersion medium. For example, in the case of water, an anionic surfactant is used, and in the case of a high-boiling non-volatile liquid insoluble in water, a nonionic surfactant is used.

  The above silica powder, dispersion medium and surfactant are kneaded (mixed and stirred) with a kneader. Thus, by kneading and mixing the silica powder with the dispersion medium in advance, the dispersibility of the silica powder is improved in the later-described step (B), and the generation of aggregates of the silica powder can be suppressed. The kneaded mixture of silica powder, dispersion medium and surfactant may be referred to as a silica dispersion (easily dispersed processed product).

  Moreover, although there is no restriction | limiting in the kneading machine to be used, it is preferable to disperse | distribute using a 3 roll mill. This three-roll mill is a kind of disperser that uses the difference in the number of rotations of the three rollers. The material is compressed using the pressure between the rollers and sheared by the speed difference to disperse and knead. can do. By compressing such a material and dispersing the silica powder using a kneader utilizing shearing, for example, the dispersibility of the silica powder is improved compared to the case of kneading using a mortar or the like. Generation of powder agglomerates can be suppressed.

  (B) Next, in a powerful kneader capable of kneading under reduced pressure, the kneaded product obtained in the step (A), polyvinyl acetate (vinyl acetate resin, polyvinyl acetate emulsion), a thickener, and an antiseptic and fungicidal agent. Add other ingredients such as (c) thickener, (d) surfactant, (e) plasticizer, (f) antiseptic and fungicide, (g) other additive aids, etc. And stir.

  Thus, in the step (A), the silica powder is kneaded and mixed in advance with the dispersion medium, whereby the dispersibility of the silica powder is improved in this step (step (B)), and the silica powder aggregates Occurrence can be suppressed. Moreover, the uniformity of the component of a clay composition can be improved and the crack after drying by the nonuniformity of a component can be suppressed.

  Moreover, content of the volatile component of the clay composition can be adjusted by kneading and mixing while reducing the pressure. Moreover, the temperature rise of the clay composition due to frictional heat during kneading of the clay composition is suppressed under reduced pressure. For this reason, alteration by the heat | fever of a clay composition can be suppressed. In addition, when a temperature gradient is generated due to frictional heat, a component (mainly moisture) that volatilizes from the clay composition is biased, which may cause cracks after drying. In contrast, the reduced pressure kneading improves the uniformity of the components (mainly moisture) that volatilize from the clay composition by suppressing the temperature rise and reducing the temperature gradient, and cracks even after drying. It is possible to produce a difficult clay composition.

  Moreover, the hardness of a clay composition can be adjusted with a sufficient precision by improving the uniformity of the component (mainly water | moisture content) which volatilizes from a clay composition. That is, the non-uniformity of the components can be reduced, and a clay composition with high uniformity of the components can be produced.

<Utilization method of clay composition>
The clay composition produced by the above method is white. This clay composition is stored in a state in which air is removed using a packaging material having a high gas barrier property such as a polyamide film. At the time of use, the opened clay composition is used for modeling or the like. The remainder of the use is sealed by removing air as much as possible, or the clay composition is wrapped in a wrap film or the like and stored.

  The clay composition of the present embodiment is moderately flexible, plastic, and rich in moldability. Furthermore, it has high adhesiveness and can be applied to glass or metal surfaces. For this reason, it is possible to decorate glass or metal surfaces while realizing good workability and formability, and the range of use is widened.

  Moreover, after modeling, the clay composition is dried (solidified) to become a dried product. In other words, the volatile components in the clay composition are volatilized and lose plasticity. The dried product has transparency (light transmittance).

  The dried product of the clay composition of the present embodiment has high transparency and has flexible flexibility even after drying. In addition, after drying, there are few white spots due to agglomeration of the silica powder, and there are few cracks due to non-uniformity of the components (mainly moisture deviation). In particular, since the white spot becomes clear after drying that exhibits transparency, the evaluation of the shaped object is lowered. For this reason, the suppression of white spots is very effective for the user.

(Example)
Hereinafter, examples will be described in detail, but the present invention is not limited to the following examples.

A clay composition was produced using various components shown in Table 1. A numerical value shows the weight ratio of each component with respect to the weight of a polyvinyl acetate emulsion. Moreover, about the manufacturing method, the various components were knead | mixed by 2 types of methods shown in Table 2, and the clay composition was obtained.

  In Table 1, various components, (a) binder, (b) filler and filler, (c) thickener, (d) surfactant, (e) plasticizer, (f) antiseptic and fungicide, (G) Correspondence with other additive aids is indicated by symbols (a) to (g). (H) is another component.

(1) Production of Clay Composition Each component shown in Table 1 was kneaded by two methods shown in Table 2 to obtain a clay composition.

Example 1
Using the components shown in the column of Example 1 in Table 1, clay compositions (Example 1-1 and Example 1-2) were obtained by the following two production steps. The following (Step-1) is a step of “dispersing silica in advance”, and corresponds to the above “method for producing a clay composition”. Further, (Step-2) is a step of “dispersing silica lastly” (see Table 2). For (Process-2), the production methods implemented in Patent Document 1 and Patent Document 2 were cited.

(Step-1)
In the case of Example 1-1, specifically, a clay composition was produced as follows. First, 20.0 g of ultrafine anhydrous silica powder, 3.0 g of a nonionic surfactant (for example, polyoxyethylene alkyl ether), 15.0 g of liquid paraffin, 9.0 g of propylene glycol, and phenyl alkyl sulfonate 2.0 g of ester and 3.0 g of glycerin were added and mixed roughly, and then kneaded by passing 5 times through a tabletop three roll mill manufactured by Inoue Seisakusho. The first kneaded material thus obtained was transferred to a container (see the above-mentioned step (A)). Thus, by mixing and kneading the silica powder with a dispersion medium (here, liquid paraffin, propylene glycol, alkylsulfonic acid phenyl ester, glycerin), the silica powder is uniformly mixed in the first kneaded product. Can be dispersed.

  Next, 10.0 g of water-soluble cellulose ether and 3.0 g of polyethylene oxide are placed in a vertical kneader made by Dalton Co., which can be vacuum-kneaded, and mixed for 1 minute. 10. Electric Works, product name Polysol S5501 (100.0 g), the first kneaded product (ultrafine anhydrous silica powder pretreated with a high-boiling non-volatile liquid insoluble in water), partially saponified polyvinyl alcohol 15. 0 g, an antiseptic and fungicide 2.0 g, and 35.0 g of water were added and mixed for 10 minutes. Next, the material adhering to the blades and side surfaces of the machine was removed and kneaded again for 10 minutes. The kneading was carried out at normal pressure for the past 20 minutes.

  Next, the inside of the kneading tank was depressurized to about −60 to −70 cmHg, and kneaded under reduced pressure for 10 minutes to obtain a second kneaded product.

  Subsequently, the hardness of the 2nd kneaded material was confirmed, and if it seemed soft, additional reduced-pressure kneading was performed. As additional vacuum kneading, vacuum kneading at −60 to −70 cmHg was performed for 3 minutes, and the hardness was confirmed again. Confirmation of hardness and kneading under reduced pressure were repeated to obtain a third kneaded product having a desired hardness. The 3rd kneaded material which finished adjustment of this hardness was made into the clay composition (refer above-mentioned process (B)). Thus, since the silica powder kneaded with the dispersion medium in advance (silica dispersion) is mixed with the polyvinyl acetate emulsion, the dispersibility of the silica powder is improved and the generation of aggregates of the silica powder is suppressed. I was able to. In addition, by kneading while reducing pressure, the amount of volatile components in the clay composition could be adjusted, and alterations due to the temperature rise of the clay composition and non-uniformity of the components could be reduced. .

(Step-2)
In the case of Example 1-2, specifically, a clay composition was produced as follows. First, 100.0 g of a polyvinyl acetate emulsion (for example, product name Polysol S5501 manufactured by Showa Denko KK), 15.0 g of partially saponified polyvinyl alcohol, 2.0 g of alkylsulfonic acid phenyl ester, and a nonionic interface 3.0 g of an activator (for example, polyoxyethylene alkyl ether), 9.0 g of propylene glycol, 3.0 g of glycerin, 2.0 g of an antiseptic and fungicide, 15.0 g of liquid paraffin, 35.0 g of water, Were sequentially poured into a blender and stirred. A Warner kneader was used as a blender. Next, 10.0 g of water-soluble cellulose ether and 3.0 g of polyethylene oxide were sequentially added little by little and stirred. This stirring was performed for 30 minutes. In the middle of this stirring, the mixer was once stopped, the contents were taken out, the undissolved material remaining on the inner wall of the mixer was removed, and the mixer was washed with a waste cloth or a scourer. Thereafter, the contents were returned to the blender, and the stirring blade was rotated in the reverse direction and stirred for 5 minutes. Thereafter, the stirring blade was again rotated in the forward direction and stirred again for 5 minutes. The stirring for 5 minutes in the reverse rotation and the subsequent re-stirring for 5 minutes were performed for the last 10 minutes of the stirring time of 30 minutes.

  Subsequently, 20.0 g of ultrafine silica powder was added little by little and stirred. This stirring was carried out for 20 minutes. Further, the mixer was washed once in the same manner as described above, the stirring blade was rotated in the reverse direction, stirred for 5 minutes, and re-stirred for 5 minutes. And the physical properties, such as the property and hardness of the clay which rose, were confirmed. The mixture thus obtained was used as a clay composition.

(Example 2)
Using the components shown in the column of Example 2 in Table 1, clay compositions (Example 2-1 and Example 2-2) were obtained by two production steps in the same manner as in Example 1. As a component of Example 2, the surfactant was changed from a nonionic surfactant (for example, polyoxyethylene alkyl ether) to an anionic surfactant (for example, sodium alkyl sulfate ester). Different from the ingredients.

(Step-1)
In the case of Example 2-1, specifically, a clay composition was produced as follows. First, 20.0 g of ultrafine anhydrous silica powder was roughly mixed with 3.0 g of an anionic surfactant (for example, sodium alkyl sulfate ester) and 35.0 g of water, and then 5 times on a tabletop three roll mill manufactured by Inoue Seisakusho. And kneaded. The first kneaded material thus obtained was transferred to a container (see the above-mentioned step (A)). Thus, silica powder can be uniformly disperse | distributed in a 1st kneaded material by mixing a silica powder with a dispersion medium (here water) beforehand.

  Next, 10.0 g of water-soluble cellulose ether and 3.0 g of polyethylene oxide are placed in a vertical kneader made by Dalton Co., which can be vacuum-kneaded, and mixed for 1 minute. 100.0 g manufactured by Denko Co., Ltd., the first kneaded product (an ultrafine anhydrous silica powder mixed with water to which a surfactant is added), 15.0 g of partially saponified polyvinyl alcohol, and antiseptic and fungicidal agent 2 0.0 g, liquid paraffin 15.0 g, propylene glycol 9.0 g, alkylsulfonic acid phenyl ester 2.0 g and glycerin 3.0 g were added and mixed for 10 minutes. Next, the material adhering to the blades and side surfaces of the machine was removed and kneaded again for 10 minutes. The kneading was carried out at normal pressure for the past 20 minutes.

  Next, the inside of the kneading tank was depressurized to about −60 to −70 cmHg, and kneaded under reduced pressure for 10 minutes to obtain a second kneaded product.

  Subsequently, the hardness of the 2nd kneaded material was confirmed, and if it seemed soft, additional reduced-pressure kneading was performed. As additional vacuum kneading, vacuum kneading at −60 to −70 cmHg was performed for 3 minutes, and the hardness was confirmed again. Confirmation of hardness and kneading under reduced pressure were repeated to obtain a third kneaded product having a desired hardness. The 3rd kneaded material which finished adjustment of this hardness was made into the clay composition (refer above-mentioned process (B)). Thus, since the silica powder kneaded with the dispersion medium in advance (silica dispersion) is mixed with the polyvinyl acetate emulsion, the dispersibility of the silica powder is improved and the generation of aggregates of the silica powder is suppressed. I was able to. In addition, by kneading while reducing pressure, the amount of volatile components in the clay composition could be adjusted, and alterations due to the temperature rise of the clay composition and non-uniformity of the components could be reduced. .

(Step-2)
Regarding Example 2-2, a clay composition was used in the same process except that the surfactant of Example 1-2 was changed from a nonionic surfactant to an anionic surfactant (for example, sodium alkyl sulfate ester). Manufactured.

  Examples 3 to 5 below are for clay compositions to which colorants (pigments, dyes) are added.

Example 3
Using the components shown in the column of Example 3 in Table 1, clay compositions (Example 3-1 and Example 3-2) were obtained by two types of production steps in the same manner as in Example 1. The components of Example 3 correspond to those obtained by adding a pigment to the components of Example 1. Regarding the timing of adding the pigment, in the case of (Step-1), that is, when the silica powder is dispersed in advance in the dispersion medium, the pigment was added together with the dispersion medium. In the case of (Step-2), that is, when adding silica powder at the end, the pigment was added at the timing of adding silica powder.

Example 4
Using the components shown in the column of Example 4 in Table 1, clay compositions (Example 4-1 and Example 4-2) were obtained by two production steps in the same manner as in Example 2. The components of Example 4 correspond to those obtained by adding a dye to the components of Example 2. Regarding the timing of addition of the dye, in the case of (Step-1), that is, when the silica powder was previously dispersed in a dispersion medium (in this case, water), the dye was added together with the dispersion medium. In this case, a water-soluble dye was used. The water-soluble dye was dispersed with water. In the case of (Step-2), that is, when adding silica powder at the end, the dye was added at the timing of adding silica powder.

(Example 5)
Using the components shown in the column of Example 5 in Table 1, clay compositions (Example 5-1 and Example 5-2) were obtained in the same manner as in Example 1 by two production steps. The components of Example 5 correspond to those obtained by adding a dye to the components of Example 1. Regarding the timing of addition of the dye, in the case of (Step-1), that is, when silica powder is dispersed in advance in a dispersion medium (in this case, liquid paraffin, propylene glycol, alkylsulfonic acid phenyl ester, glycerin). Added the dye together with the dispersion medium. In this case, an oil-soluble dye was used. That is, the oil-soluble dye was dispersed with a non-volatile liquid insoluble in water. In the case of (Step-2), that is, when adding silica powder at the end, the dye was added at the timing of adding silica powder.

  Comparative Examples 1 to 3 are for clay compositions corresponding to Patent Documents 1 to 3 described above.

(Comparative Example 1)
Using the components shown in the column of Comparative Example 1 in Table 1, the clay composition (Comparative Example 1) was produced by the same production process as in (Process-2) of Example 1, that is, the process of finally adding silica powder. Obtained. This clay composition and its manufacturing process correspond to the above-mentioned Patent Document 2 (Japanese Patent Laid-Open No. 2006-330412).

(Comparative Example 2)
Using the components shown in the column of Comparative Example 2 in Table 1, the clay composition (Comparative Example 2) was prepared by the same manufacturing process as in (Process-2) of Example 1, that is, the process of finally adding silica powder. Obtained. This clay composition and its manufacturing process correspond to the above-mentioned Patent Document 1 (Japanese Patent Laid-Open No. 2005-281743).

(Comparative Example 3)
Using the components shown in the column of Comparative Example 3 in Table 1, the clay composition (Comparative Example 3) was prepared by the same production process as in (Process-2) of Example 1, that is, the process of finally adding silica powder. Obtained. In Comparative Example 3, the main binder of Comparative Example 1 is changed to a polyacrylic acid emulsion. This clay composition and the production process thereof correspond to the combination of the compositions of Patent Document 1 (Japanese Patent Laid-Open No. 2005-281463) and Patent Document 3 (Japanese Patent Laid-Open No. 59-69466).

(2) Evaluation of clay composition and dried product The clay composition and dried product thereof were evaluated using the clay compositions of Examples and Comparative Examples described in the section (1) above.

(2-a) Adhesiveness The adhesiveness was evaluated. As the evaluation method for adhesiveness, the clay compositions of Examples and Comparative Examples were formed into spherical products having a diameter of 2.5 cm. Then, it pressed and adhered to the board of paper, aluminum, iron, and PET so that 1/3 of the sphere was deformed. The plate was erected so that the bonding surface was perpendicular to the ground, and the time (bonding time, unit: second) for the clay composition to peel off from the plate was measured. The results are shown in Table 3.

  Regarding adhesiveness, any of the examples (1-1, 2-1, 3-1, 4-1, 5-1, 1-2, 2-2, 3-2, 4-2, 5-2) Also, good adhesiveness was confirmed. In addition, good adhesiveness was confirmed in any material of paper, aluminum, iron, and PET (polyethylene terephthalate). Moreover, although not shown in the table | surface, the adhesiveness of clay compositions was also favorable. In particular, it has been revealed that it has good adhesion even to a metal having a smooth surface.

  In Comparative Examples 1 to 3, adhesion to paper could be confirmed, but adhesion to other materials (aluminum, iron, PET) was low. In particular, Comparative Example 3 using a polyacrylic acid emulsion as the main binder had extremely low adhesion to materials other than paper (aluminum, iron, PET). Moreover, the adhesiveness between clay compositions was extremely low. Also in Comparative Example 1 and Comparative Example 2, the adhesion to materials other than paper (aluminum, iron, PET) was low. Moreover, the adhesiveness between clay compositions was also low.

  Thus, it was found that the clay composition using the polyvinyl acetate emulsion as the main binder has high adhesiveness. In addition, in the case of (Step-1), that is, when silica powder is dispersed in a dispersion medium in advance, and in the case of (Step-2), that is, when silica powder is added at the end, Any of these proved to be expensive.

(2-b) Transparency Evaluation on transparency was performed. In the evaluation method of transparency, the clay compositions of Examples and Comparative Examples were thinly extended to a thickness of 3 mm, dried for 10 days, and the transparency of the dried product (clay composition after drying) was compared. For the comparison of transparency, a line was drawn with black magic on white paper, and the line was confirmed through the dry matter. The evaluation was made in three stages. The case where the boundary line could be confirmed firmly was indicated by ◯, the case where the line itself could be confirmed but the boundary line was not clear was indicated by △, and the case where the line could not be confirmed was indicated by ×. The results are shown in Table 4.

  Regarding transparency, good transparency was confirmed in Examples (1-1, 2-1, 4-1, 5-1).

  It was Comparative Example 3 that had the lowest transparency. In Comparative Example 3, despite the long drying time of 10 days, it was not dried to the inside and remained in a white turbid state. This is considered to be caused by the fact that when the polyacrylic acid emulsion of the main binder is dried, a very dense surface film is formed to inhibit evaporation of moisture inside.

  Next, the lower transparency was in Examples (3-1, 1-2, 2-2, 3-2, 4-2, 5-2) and Comparative Examples 1 and 2, and among them, transparency Were lower in Examples 1-2 and 2-2. Regarding Example 3-1, since the used pigment was not transparent, the transparency was lower than that of Examples 1-1 and 2-1.

  Since the polyvinyl acetate emulsion has a high viscosity, in the case of (Step-2), that is, when silica powder is added at the end, the viscosity of the clay composition increases and the ultrafine anhydrous silica powder is well dispersed. It is considered that the cause was not.

  On the other hand, Comparative Examples 1 and 2 were higher in transparency as the whole dried product than Examples 1-2 and 2-2, but white spots (innumerable white spots) were confirmed in the dried product. As a result, the boundary surface could not be identified firmly.

  On the other hand, in the examples (1-1, 2-1, 4-1, 5-1), white spots were hardly confirmed, and a dried product with extremely high transparency could be obtained. This is considered to be because (dispersion-1), that is, by dispersing silica powder in a solvent in advance, the dispersibility of silica powder was improved and the generation of aggregates of silica powder could be suppressed. .

(2-c) Cracking Evaluation regarding cracking was performed. For the presence or absence of cracks, the clay compositions of Examples and Comparative Examples were formed into three spherical products having a diameter of 1.5 cm. Then, it was made to dry for 30 days, and the presence or absence of the crack (crack) of the surface of the dried material (clay composition after drying) was compared. The results are shown in Table 5.

  Regarding the presence or absence of cracks (cracks), good results were obtained in the examples (1-1, 2-1, 3-1, 4-1, 5-1).

  In Examples (1-2, 2-2, 3-2, 4-2, 5-2) and Comparative Examples 1 to 3, cracks were confirmed. Especially, about the crack, Example 1-2, 2-2 was notably seen rather than the comparative examples 1 and 2.

  As for the evaluation of the crack, as in the case of the transparency, the uniformity of the silica powder and the volatile component (mainly moisture) is obtained by dispersing the silica powder in the dispersion medium in advance (step-1). It is considered that a clay composition that can improve cracking resistance and hardly crack even after drying can be produced.

(2-d) Colorability About colorability, about Examples 3-5, it comparatively examined.

  About Example 3-1 and 3-2, coloring was able to be confirmed about both. Since the pigment used was opaque, the transparency was slightly lowered, but the pigment could be colored while maintaining appropriate transparency. In particular, Example 3-1 with higher transparency showed better color development than Example 3-2.

  About Example 4-1 and 4-2, favorable coloring was confirmed in Example 4-1. About Example 4-2, since the dye exhibits transparency, white spots considered as secondary aggregates of silica powder are conspicuous, and sufficient coloring and transparency are obtained as compared with Example 4-1. I couldn't. Usually, since water-soluble dyes develop color by reaction with water, the original color cannot be obtained after the water has evaporated. The coloring seen in Examples 4-1 and 4-2 is thought to be due to dry particles of the water-soluble dye.

  Since Example 5-1 can be sufficiently dispersed in the plasticizer, the coloring was good, and the color development after drying was also good. For 5-2, the dye was not well dispersed in the clay and was not sufficiently colored.

(Other examples)
Although not clearly shown in Table 1, the formulation in which the liquid paraffin of Example 1 was changed to silicon oil, or pregelatinized starch or powder emulsion was added (Step-1), that is, silica powder was added. The same evaluation (adhesiveness, transparency, cracking) was performed on a clay composition produced by a method of dispersing in a dispersion medium in advance. The evaluation results were the same as in Example 1.

(Other examples)
The components of the clay composition of the present invention and the blending ratio thereof are not limited to the values in the above examples, but can be appropriately changed and adjusted within the following ranges.

  For example, in the above examples, Showa Denko Co., Ltd., Polysol S-5501 was used as the polyvinyl acetate emulsion, but in addition, Showa Denko Co., Ltd. Polysol S series, Aika Industries Aika Ivon series, High Pressure Polyvinyl acetate emulsions such as Pegar series manufactured by Gas Industry Co., Ltd. can be used. Among these products, those having a viscosity of 10,000 to 100,000 mPa · s are preferably used.

  The polyvinyl acetate emulsion is preferably blended in the range of 30 to 70% by weight. When the polyvinyl acetate emulsion has such a blending ratio, the effects of other blending components can be sufficiently exhibited while imparting adhesiveness to the clay composition. From such a viewpoint, the blending ratio is more preferably 40 to 60% by weight, and further preferably 45 to 55% by weight.

  The ultrafine anhydrous silica powder is preferably blended in the range of 5.0 to 10.0% by weight. When the ultrafine particle anhydrous silica powder is in such a range, transparency can be imparted to the clay, and the workability and shape retention of the clay can be made sufficient. From such a viewpoint, the blending ratio is more preferably 6.0 to 9.0% by weight, and still more preferably 7.0 to 8.0% by weight.

  The nonionic surfactant and the anionic surfactant are preferably blended in the range of 0.1 to 5.0% by weight. If the nonionic surfactant is in this range, the dispersibility of the ultrafine anhydrous silica powder in the polyvinyl acetate emulsion can be improved, resulting in improved transparency and cracking. It is possible to make a clay composition that is difficult to do. From such a viewpoint, the blending ratio is more preferably 0.5 to 3.0% by weight, and further preferably 1.0 to 1.5% by weight.

  In addition, the partially saponified polyvinyl alcohol is 5.0 to 10.0% by weight, the water-soluble cellulose ether is 2.0 to 7.0% by weight, the polyethylene oxide is 0.5 to 5.0% by weight, and the propylene glycol is 2%. 0.0 to 6.0 wt%, liquid paraffin is 3.0 to 10.0 wt%, alkylsulfonic acid phenyl ester is 0.3 to 5.0 wt%, glycerin is 0.3 to 5.0 wt%, The antiseptic and antifungal agent is preferably blended in the range of 0.3 to 5.0% by weight, water in the range of 5.0 to 40.0% by weight, and the pigment and dye in the range of 0.0 to 1.0% by weight.

  Moreover, in the said Example, although the pigment and the dye were illustrated as a coloring material, it is also possible to use resin-made beads, mineral raw materials (mica pearl, metallic flakes), etc. as a coloring material. According to such a material, it is also possible to express uneven coloring. The clay composition may be in the form of a paste or a liquid. Such adjustment can be performed, for example, by increasing or decreasing the amount of water contained in the clay composition, the amount of high-boiling non-volatile liquid insoluble in water, or the amount of silica powder. Thus, by changing the physical state, the wettability with the adherent is improved, and the adhesiveness can be further improved.

  As described above, the present invention is not limited to the above-described embodiments and examples, and various modifications can be made without departing from the scope of the invention.

  INDUSTRIAL APPLICATION This invention can be utilized as a clay composition which has transparency after drying, and its manufacturing method. In the field of handicrafts, it is possible to create a wider range of shaped objects than in the past by expanding the range of combinations of clay compositions exhibiting transparency and other shaped materials.

Claims (14)

A clay composition comprising a mixture of a polyvinyl acetate emulsion and a silica dispersion,
The silica dispersion is a clay composition, which is a mixture of a nonionic surfactant, a high-boiling non-volatile liquid insoluble in water, and silica. A clay composition comprising a mixture of a polyvinyl acetate emulsion and a silica dispersion,
The silica dispersion is a clay composition, which is a mixture of an anionic surfactant, water, and silica. The clay composition of claim 1, wherein
The clay composition, wherein the high-boiling non-volatile liquid insoluble in water is a plasticizer. The clay composition according to claim 1 or 2,
A clay composition having a colorant. The clay composition according to claim 1 or 2,
The clay composition is lightly transmissive by drying. (A) a step of forming a silica dispersion by mixing a nonionic surfactant, a high-boiling non-volatile liquid insoluble in water, and silica;
(B) mixing a polyvinyl acetate emulsion and the silica dispersion;
A method for producing a clay composition. (A) a step of forming a silica dispersion by mixing an anionic surfactant, water, and silica;
(B) mixing a polyvinyl acetate emulsion and the silica dispersion;
A method for producing a clay composition. In the manufacturing method of the clay composition of Claim 6,
The method for producing a clay composition, wherein the high-boiling non-volatile liquid insoluble in water is a plasticizer. In the manufacturing method of the clay composition of Claim 6,
(C) A method for producing a clay composition, comprising a step of adding a colorant. In the manufacturing method of the clay composition of Claim 6,
After the step (b),
(D) A method for producing a clay composition, comprising a step of adjusting the hardness of the clay composition by kneading the clay composition under reduced pressure and volatilizing some components of the clay composition. In the manufacturing method of the clay composition of Claim 7,
(C) A method for producing a clay composition, comprising a step of adding a colorant. In the manufacturing method of the clay composition of Claim 7,
After the step (b),
(D) A method for producing a clay composition, comprising a step of adjusting the hardness of the clay composition by kneading the clay composition under reduced pressure and volatilizing water of the clay composition. In the manufacturing method of the clay composition according to claim 9,
After the step (c),
(D) A method for producing a clay composition, comprising a step of adjusting the hardness of the clay composition by kneading the clay composition under reduced pressure and volatilizing some components of the clay composition. In the manufacturing method of the clay composition of Claim 11,
After the step (c),
(D) A method for producing a clay composition, comprising a step of adjusting the hardness of the clay composition by kneading the clay composition under reduced pressure and volatilizing water of the clay composition.