WO2020095837A1 - Modified zirconium phosphate tungstate, negative thermal expansion filler and polymer composition - Google Patents

Abstract

The purpose of the present invention is to provide a modified zirconium phosphate tungstate which is suppressed in dissolution of ions from particles and exhibits excellent performance as a negative thermal expansion material, and which is capable of producing a low thermal expansion material. A modified zirconium phosphate tungstate according to the present invention is obtained by covering the surfaces of zirconium phosphate tungstate particles with a fatty acid or a derivative thereof. It is preferable that the zirconium phosphate tungstate is covered with a silane compound. The present invention also provides a negative thermal expansion filler which is composed of this modified zirconium phosphate tungstate. The present invention also provides a polymer composition which contains this negative thermal expansion filler and a polymer compound.

Description

Modified zirconium tungstate phosphate, negative thermal expansion filler and polymer composition

The present invention relates to a modified zirconium tungstate phosphate, a negative thermal expansion filler using the same, and a polymer composition.

-In general, substances have the property of increasing in length and volume due to thermal expansion when the temperature rises. On the other hand, a material exhibiting a negative thermal expansion, which has a property that the volume is reduced by the application of heat, is known (hereinafter, also referred to as “negative thermal expansion material”). The material exhibiting negative thermal expansion is used, for example, together with other materials to suppress the volume change due to the thermal expansion of the material due to the temperature change.

Examples of materials exhibiting negative thermal expansion include β-eucryptite, zirconium tungstate (ZrW ₂ O ₈ ), zirconium tungstate phosphate (Zr ₂ WO ₄ (PO ₄ ) ₂ ), Zn _x Cd _{1- x} (CN) ₂ , manganese nitride, bismuth / nickel / iron oxide and the like are known.

The linear expansion coefficient of zirconium phosphate tungstate particles is −3.4 to −3.0 ppm / ° C. in the temperature range of 0 to 400 ° C., and it is known that the negative thermal expansion property is large. A material having low thermal expansion can be produced by using the zirconium tungstate phosphate particles and a material exhibiting positive thermal expansion (hereinafter also referred to as “positive thermal expansion material”) in combination (Patent Document (See 1-3). Further, it has been proposed to use a polymer compound such as a resin, which is a positive thermal expansion material, in combination with a negative thermal expansion material (Patent Documents 4 to 5).

JP, 2005-35840, A Japanese Patent Laid-Open No. 2015-10006 International Publication No. 2017/61403 Pamphlet JP, 2015-38197, A JP, 2016-113608, A

However, when zirconium phosphate tungstate is brought into contact with water, zirconium, tungsten and phosphorus in the structure are eluted as ions, which results in a decrease in performance as a negative thermal expansion material, resin There is a problem that the performance of the molded product deteriorates when mixed with the material.

Further, in addition to the above problems, zirconium phosphate tungstate has a low affinity with a hydrophobic polymer compound such as a resin, so that it is difficult to uniformly disperse it in the polymer compound, and as a result, It was difficult to obtain the desired low thermal expansion material.

Therefore, the object of the present invention is to suppress the elution of zirconium ions in zirconium phosphate tungstate, tungsten ions and phosphorus ions into water, and can be preferably used as a negative thermal expansion filler contained in a polymer compound. It is intended to provide a modified zirconium tungstate phosphate, a negative thermal expansion filler using the same, and a polymer composition.

The inventors of the present invention have conducted extensive studies in view of the above problems, and the surface of zirconium tungstate phosphate particles is coated with a fatty acid or a derivative thereof to modify the surface of the particles. It was found that the elution of ions, tungsten ions and phosphorus ions can be effectively suppressed. Further, the inventors have found that the modified zirconium tungstate phosphate can be uniformly dispersed in a polymer compound such as a resin to produce a low thermal expansion material containing a negative thermal expansion filler, and have completed the present invention. ..

That is, the first invention provided by the present invention is a modified zirconium tungstate phosphate in which the particle surface of zirconium tungstate phosphate particles is coated with a fatty acid or a derivative thereof.

The second invention provided by the present invention is a negative thermal expansion filler comprising the modified zirconium tungstate phosphate of the first invention.

A third invention provided by the present invention is a polymer composition comprising the negative thermal expansion filler of the second invention and a polymer compound.

According to the modified zirconium tungstate phosphate of the present invention, even when it comes into contact with water, the elution of zirconium ions, tungsten ions and phosphorus ions is effectively suppressed, and excellent performance as a negative thermal expansion material is expressed. be able to. Further, the modified zirconium tungstate phosphate of the present invention can be uniformly dispersed in a polymer compound such as a resin, and a low thermal expansion material containing a negative thermal expansion filler can be successfully produced.

FIG. 1 is a scanning electron microscope photograph showing the shape of zirconium phosphate tungstate particle sample 1. FIG. 2 is a scanning electron microscope photograph showing the shape of the zirconium phosphate tungstate particle sample 2.

Hereinafter, the present invention will be described based on preferred embodiments. In the modified zirconium tungstate phosphate (hereinafter, also referred to as “modified ZWP”) of the present invention, the surface of zirconium tungstate phosphate particles (hereinafter, also referred to as “ZWP particles”) is a fatty acid. Alternatively, it is coated with a derivative thereof. That is, the modified zirconium tungstate phosphate of the present invention comprises particles having a zirconium tungstate phosphate particle as a core material and a layer of a fatty acid or a derivative thereof formed on the surface of the particle. In the following description, “L to M” (where L and M are arbitrary numbers) means “L or more and M or less” unless otherwise specified.

The fatty acid or its derivative contained in the modified ZWP may coat the entire surface of the ZWP particles evenly or continuously, or may coat only a part of the surface of the particles. In the former case, in the modified ZWP, the entire surface of the ZWP particles is completely covered with the fatty acid or its derivative, and the surface of the particles is not exposed. In the latter case, the modified ZWP is composed of a site whose surface is made of zirconium tungstate phosphate as an underlayer and a site made of a fatty acid or its derivative. When the fatty acid or its derivative covers only a part of the surface of the ZWP particles, the coating site may be continuous, may be discontinuously coated in a sea-island shape, or a combination thereof. Good.

The raw material zirconium tungstate phosphate used in the present invention is represented by the following general formula (1).
Zr _x (WO ₄ ) _y (PO ₄ ) _z (1)
(In the formula, x is 1.7 ≦ x ≦ 2.3, preferably 1.8 ≦ x ≦ 2.2, and y is 0.85 ≦ y ≦ 1.15, preferably 0.90 ≦ y ≦ 1.10 and z is 1.7 ≦ z ≦ 2.3, preferably 1.8 ≦ z ≦ 2.2.)

The fatty acid used in the present invention is preferably a saturated or unsaturated linear or branched mono- or polycarboxylic acid, and a saturated or unsaturated linear or branched monocarboxylic acid. More preferably, it is a saturated or unsaturated linear monocarboxylic acid, and even more preferably. The fatty acid preferably has 7 or more carbon atoms. The derivative means a salt or amide of the fatty acid.

The fatty acid or derivative thereof used in the present invention preferably has 7 to 23 carbon atoms, and more preferably 10 to 20 carbon atoms. Examples of such fatty acids or derivatives thereof include saturated fatty acids such as capric acid, lauric acid, myristic acid, palmitic acid and stearic acid, unsaturated fatty acids such as oleic acid, linoleic acid, linolenic acid and arachidonic acid, or these Examples thereof include metal salts or amides. Examples of the metal salt of fatty acid include alkali metal, alkaline earth metal, transition metals such as Zr, Cr, Mn, Fe, Co, Ni, Cu and Ag, and salts of metals other than transition metals such as Al and Zn. And a polyvalent metal salt of Al, Zn, W, V or the like is preferable. The fatty acid metal salt may be a mono-form, di-form, tri-form, tetra-form or the like depending on the valence of the metal. The fatty acid metal salt may be any combination thereof. With such a configuration, it is possible to suppress the elution of ions into water and improve the performance as a negative thermal expansion material, and to facilitate uniform dispersion in a positive thermal expansion material such as resin. be able to.

In the modified ZWP of the present invention, the coating amount (abundance) of the fatty acid or its derivative is preferably 0.05% by mass to 30% by mass, more preferably 0.1% by mass to 10% by mass based on the ZWP particles. %, And more preferably 0.2% by mass to 5.0% by mass. When the coating amount is in such a range, elution of zirconium ions, tungsten ions and phosphorus ions from the modified ZWP can be effectively suppressed and the performance as a negative thermal expansion material can be enhanced. Moreover, the hydrophobicity of the modified ZWP becomes high, and when used as a negative thermal expansion filler, the dispersibility in a positive thermal expansion material such as a resin becomes good.

From the viewpoint of improving the dispersibility in the positive thermal expansion material and the filling characteristics, the ZWP particles as a raw material include elements other than P, W, Zr, and O that are elements contained in the general formula (1) (hereinafter, Is also referred to as “sub-component element”).

As the sub-component element, for example, an alkali metal element such as Li, Na and K, an alkaline earth metal element such as Mg, Ca, Sr and Ba, Ti, V, Cr, Mn, Fe, Co, Ni and Cu, Transition metal elements such as Y, Nb, Mo, Ag, Hf and Ta, rare earth elements such as La, Ce, Nd, Sm, Eu, Tb, Dy, Ho and Yb, Al, Zn, Ga, Cd, In and Sn. , Metal elements other than transition metals such as Pb and Bi, semi-metal elements such as B, Si, Ge, Sb and Te, non-metal elements such as S, halogen elements such as F, Cl, Br and I. Can be mentioned. One or two or more of these elements may be contained in the particles. Among these, from the viewpoint of further improving the dispersibility in the positive thermal expansion material and the filling characteristics, it is preferable that the particles contain at least one sub-component element of Mg, Al and V. From the viewpoint of facilitating suppression of the thermal expansion coefficient of the expansive material, it is more preferable that both Mg and Al are contained as sub-component elements.

From the viewpoint of having excellent negative thermal expansion property and excellent dispersibility in the positive thermal expansion material and filling properties, the content of the accessory component element in the ZWP particles is preferably ZWP particles, The content is 0.1% by mass to 3% by mass, and more preferably 0.2% by mass to 2% by mass. When two or more sub-component elements are contained, the content of the sub-component element is calculated based on the total mass of the sub-component elements. Further, the content of the accessory component element in the modified ZWP can be set to the same range as described above. The content of the subcomponent element can be measured by a method such as a powder pressing method or a molten glass bead method using a measuring device such as a fluorescent X-ray analyzer.

From the viewpoint of further improving the negative thermal expansion property, and the dispersibility in the positive thermal expansion material and the filling characteristics, when both Mg and Al are included as secondary component elements, the content of the Al element in the ZWP particles is , Preferably 100 ppm to 6000 ppm, more preferably 1000 ppm to 5000 ppm. Further, from the viewpoint of having a practical linear expansion coefficient and further being excellent in dispersibility and filling characteristics, the content of the Mg element is preferably 0.1% by mass to 3% by mass with respect to the ZWP particles. %, And more preferably 0.22% by mass to 2% by mass.

The particle shape of the modified ZWP is not particularly limited, and examples thereof include spherical, granular, plate-like, scale-like, whisker-like, rod-like, filament-like, and irregular crushed stones having one or more ridges ( Hereinafter, this may also be referred to as "crushed form") or a combination thereof.

When the modified ZWP of the present invention is mixed with a positive thermal expansion material such as a resin, the modified ZWP is further coated with a silane coupling agent described later for the purpose of improving the adhesion between the modified ZWP and the positive thermal expansion material. Preferably. That is, the modified ZWP of the present invention is preferably coated with a silane compound in addition to the fatty acid or its derivative. The silane compound is a compound of an organic silane having an alkyl group or an amino group directly bonded to the atom of Si, and includes a hydrolysis product of a silane coupling agent containing an organic silane, a dehydration condensation product, and the like. By being coated with a silane compound in addition to the fatty acid or its derivative, a denser coating layer having higher hydrophobicity can be formed on the surface of the ZWP particles. As a result, the elution of ions from the modified ZWP can be further reduced, and the modified ZWP can be effectively and uniformly dispersed in the positive thermal expansion material such as resin.

The modified ZWP is coated with a silane compound such that, for example, (a) a layer of the fatty acid or a derivative thereof on which the entire surface of the ZWP particles is evenly coated, and a layer of the silane compound that uniformly coats the entire surface of the layer is present. (C) ZWP particles in which (b) a layer of the fatty acid or a derivative thereof, which covers the entire surface of the ZWP particles evenly, and a layer of the silane compound, which covers only part of the surface of the layer, are present. (D) one of the surfaces of the ZWP particles, in which a layer of the silane compound uniformly covering the entire surface of the ZWP particles including the layer is present on the layer of the fatty acid or its derivative that covers only part of the surface of the ZWP particles. A layer of the fatty acid or its derivative coated only on the surface and a layer of the silane compound coated on only part of the surface of the particle are present on the surface of the ZWP particle. And (e) a form in which the layer made of the mixture of the fatty acid or its derivative and the silane compound uniformly covers the entire surface of the ZWP particles, or (f) a layer made of the mixture of the fatty acid or its derivative and the silane compound is ZWP particles. An example is a form in which only a part of the surface is covered.

In detail, in the cases of the above-mentioned forms (a) and (c), the modified ZWP is such that the entire surface of the ZWP particles is completely covered with the silane compound, the surface of the particles and the surface of the layer of the fatty acid or its derivative are Is not exposed. In the case of the form (b), the modified ZWP is composed of a site whose surface is made of the fatty acid or its derivative and a site made of a silane compound. In the case of the form (d), the surface of the modified ZWP is composed of the site composed of the fatty acid or its derivative and the site composed of the silane compound, and depending on the configuration mode, the underlying tungsten phosphate. There is a site consisting of zirconium acid. In the case of the form (e), in the modified ZWP, the entire surface of the ZWP particles is completely covered with the mixture of the fatty acid or its derivative and the silane compound, and the surface of the particles is not exposed. . In the case of the form (f), the modified ZWP is composed of a site whose surface is made of zirconium phosphate tungstate as an underlayer and a site made of a mixture of the fatty acid or its derivative and a silane compound. When the silane compound covers only a part of the surface of the ZWP particles or the fatty acid layer, the coating site may be continuous, may be discontinuously coated in a sea-island shape, or a combination thereof. You may.

The coating amount (abundance) of the silane compound of the modified ZWP is preferably 0.05% by mass to 30% by mass, more preferably 0.1% by mass to 10% by mass, and further preferably 0. It is 2% by mass to 5% by mass. When the coating amount is in such a range, elution of zirconium ions, tungsten ions and phosphorus ions from the modified ZWP can be further suppressed, and the performance as a negative thermal expansion material can be further enhanced. Further, since the hydrophobicity of the modified ZWP is further increased, when the modified ZWP is used as the negative thermal expansion filler, the dispersibility in the positive thermal expansion material such as resin is improved.

According to the modified zirconium phosphate tungstate of the present invention in which the surface of zirconium phosphate tungstate particles is coated with a fatty acid or a derivative thereof, zirconium or tungsten from zirconium phosphate tungstate can be obtained even when contacted with water. Also, the ion elution of phosphorus can be effectively suppressed, and excellent performance as a negative thermal expansion material can be exhibited. Further, since the modified zirconium tungstate phosphate of the present invention has a hydrophobic group derived from a fatty acid, it can be uniformly dispersed in a hydrophobic polymer compound such as resin, resulting in low thermal expansion. The sexual material can be successfully manufactured. Further, there is an advantage that it is possible to suppress the aggregation of the modified ZWP particles.

The preferred method for producing the modified ZWP of the present invention will be described below. The method for producing the modified ZWP is roughly divided into two steps: a step of reacting a zirconium source, a tungsten source and a phosphorus source to obtain ZWP particles, and a step of coating the surface of the obtained ZWP particles with a fatty acid or a derivative thereof. To be done.

First, ZWP particles are obtained by reacting a zirconium source, a tungsten source and a phosphorus source. The method for producing ZWP particles used in the present invention is not particularly limited, and for example, (i) zirconium phosphate, tungsten oxide, and a mixture obtained by mixing a reaction accelerator such as MgO in a wet ball mill can be used. Method of firing (see, for example, JP-A-2005-35840), (ii) a zirconium source such as zirconium chloride, a tungsten source such as ammonium tungstate and a phosphorus source such as ammonium phosphate are wet-mixed to obtain a mixture. (See, for example, JP-A-2015-10006), (iii) a method of firing a mixture containing zirconium oxide, tungsten oxide, and ammonium dihydrogen phosphate (for example, Materials Research Bulletin, 44 (2009), p.2045-2049), or (Iv) A method in which a mixture of a tungsten compound and an amorphous compound containing phosphorus and zirconium is used as a reaction precursor, and the reaction precursor is fired (see, for example, International Publication No. 2017/061402 pamphlet). Be done.

From the viewpoint of facilitating handling when using the modified ZWP as a filler for the positive thermal expansion material, the BET specific surface area of the ZWP particles is preferably 0.1 m ² / g to 50 m ² / g, more preferably 0. It is 1 m ² / g to 20 m ² / g. The BET specific surface area of the modified ZWP can be set in the same range as described above. The BET specific surface area can be measured by using, for example, a BET specific surface area measuring device (AUTOSORB-1 manufactured by Kantachrome Instruments Co., Ltd.).

From the same viewpoint, the ZWP particles have an average particle size of preferably 0.02 μm to 50 μm, more preferably 0.5 μm to 30 μm. The average particle diameter of the modified ZWP can be set in the same range as described above. The average particle diameter can be determined as an arithmetic average value of the maximum lengths of particles obtained by observing arbitrary 100 particles with a scanning electron microscope.

The particle shape of ZWP particles is not particularly limited, and may be, for example, spherical, granular, plate-like, scale-like, whisker-like, rod-like, filament-like, crushed, or a combination thereof.

From the viewpoint of obtaining a modified ZWP excellent in negative thermal expansion, which is easy to control various properties such as the particle diameter, the specific surface area, and the particle shape described above by an industrially advantageous method, as a method for producing ZWP particles, It is preferable to use ZWP particles produced by method (iv).

Next, the surface of the ZWP particles obtained by the above method is coated with a fatty acid or its derivative. This step can be performed by a wet method or a dry method.

When the coating treatment of the fatty acid or its derivative is performed by a wet method, for example, ZWP particles are immersed in a dispersion liquid containing the fatty acid or its derivative at a desired concentration to form a slurry, and the slurry is spray-dried, or the slurry is The target modified ZWP can be obtained by solid-liquid separation and drying the obtained solid content. The concentration of the fatty acid or its derivative in the dispersion liquid may be appropriately adjusted so that the coating amount of the fatty acid or its derivative in the modified ZWP falls within the above range.

When the coating treatment of the fatty acid or its derivative is carried out by a dry method, for example, the ZWP particles and the solid fatty acid or its derivative are mixed by using a mixing device such as a Henschel mixer, an air flow type pulverizer, or ZWP. The target modified ZWP can be obtained by mixing the particles with a diluting solution prepared by diluting the fatty acid or its derivative with a solvent, and then heating and drying the mixture if necessary. In the dry method, since a modified ZWP is produced by using a mixture of ZWP particles and the fatty acid or its derivative as it is, the charged amount of the fatty acid or its derivative and the coating amount are substantially the same.

The thus-produced modified ZWP of the present invention suppresses ion elution from the modified ZWP even in the presence of water, and is suitably used as a negative thermal expansion material. The modified ZWP of the present invention is zirconium (Zr) eluted in water when 1 g of the modified ZWP is heat-treated with 70 mL of water at 85 ° C. for 1 hour, then cooled to 25 ° C. and left standing for 24 hours. The amount of ions, as its mass, is preferably 20 μg or less, more preferably 10 μg or less, the amount of tungsten (W) ions is preferably 400 μg or less, more preferably 300 μg or less, and the amount of phosphorus (P) ions is preferably Is 100 μg or less, more preferably 50 μg or less. The amount of these ions may be any amount as long as the total amount of ions of each element of Zr, W, and P is within the above range regardless of the valence of the ions. The amount of each ion can be measured using, for example, an ICP emission spectroscope.

The various physical properties of the modified ZWP described above can be achieved, for example, by using ZWP particles having the physical properties and shapes described above and appropriately adjusting the reaction amount with the fatty acid or its derivative.

Regardless of whether the coating treatment is performed by the wet method or the dry method, it is preferable to further perform heat treatment after the coating treatment. The temperature of the heat treatment is preferably 70 ° C to 230 ° C, more preferably 100 ° C to 210 ° C, and the time of the heat treatment is preferably 30 minutes or more, more preferably 1 hour to 10 hours. The atmosphere in the heat treatment may be vacuum, an inert gas atmosphere, or an air atmosphere. By performing the heat treatment, the fatty acid or its derivative existing on the surface of the ZWP particles has a dense structure, and the elution of ions from the modified ZWP in the presence of water is further suppressed. As a result, a modified ZWP having excellent negative thermal expansion can be obtained.

When the heat treatment is performed, it is particularly preferable that the temperature of the heat treatment is equal to or higher than the melting point of the fatty acid or its derivative and lower than the decomposition point of the fatty acid or its derivative. By treating at such a heating temperature, the coating layer existing on the surface of the ZWP particles has a more dense structure, and the ion elution from the modified ZWP in the presence of water is further suppressed.

In the present invention, the modified ZWP coated with a silane compound by performing a coating treatment with a silane coupling agent (hereinafter, also referred to as “Si-treated modified ZWP”) is the following method (A) or ( B). Whichever method is used, the effects of the present invention are sufficiently exhibited.

In method (A), ZWP particles as a raw material are coated with a fatty acid or a derivative thereof and then with a silane coupling agent to obtain Si-treated modified ZWP. In the present method, the modified ZWP having any one of the forms (a) to (d) is suitably produced.

Specifically, in the method (A), the ZWP particles are coated with the fatty acid or its derivative as described above, and then the coating treatment with the silane coupling agent is performed in a wet or dry manner.

When the coating treatment of the silane coupling agent is performed by a wet method, the dispersion liquid containing the silane coupling agent described below at a desired concentration is dipped into the ZWP particles coated with the fatty acid or a derivative thereof to form a slurry, The silane coupling agent is hydrolyzed and condensed by spray-drying the slurry or by solid-liquid separating the slurry and drying the solid content. As a result, the desired Si-processed modified ZWP can be obtained. The concentration of the silane coupling agent in the dispersion liquid may be appropriately adjusted so that the coating amount of the silane compound in the modified ZWP falls within the above range.

When the coating treatment of the silane coupling agent is carried out by a dry method, for example, the ZWP particles coated with the fatty acid or its derivative and the silane coupling agent are mixed by using a mixing device such as a Henschel mixer or an air pulverizer. Mixing or mixing ZWP particles coated with the fatty acid or its derivative and a diluting solution prepared by diluting a silane coupling agent with a solvent, and then heat treating under the above-mentioned conditions, if necessary. , Silane coupling agent is hydrolyzed and condensed. As a result, the desired Si-processed modified ZWP can be obtained. In the dry method, the modified ZWP is produced by using the mixture of the ZWP particles coated with the fatty acid or its derivative and the silane coupling agent as it is. Therefore, the coating amount of the silane compound is equal to that of the silane coupling agent. It is almost the same as the value theoretically calculated from the charged amount.

In method (B), ZWP particles as a raw material are coated with a fatty acid or a derivative thereof and with a silane coupling agent to obtain Si-treated modified ZWP. That is, each coating process for ZWP particles is performed in one step. In this method, the modified ZWP having the form (e) or (f) is preferably produced.

When the treatment with the fatty acid or its derivative and the treatment with the silane coupling agent are carried out by a wet method, the ZWP particles are dipped in a dispersion liquid containing the fatty acid or its derivative and the silane coupling agent at desired concentrations. The slurry is spray-dried, or the slurry is subjected to solid-liquid separation and the solid content is dried to hydrolyze and condense the silane coupling agent. As a result, the desired Si-processed modified ZWP can be obtained. The concentrations of the fatty acid or its derivative and the silane coupling agent in the dispersion may be appropriately adjusted so that the coating amounts of the fatty acid or its derivative and the silane compound in the modified ZWP fall within the ranges described above.

When the treatment with a fatty acid or a derivative thereof and the treatment with a silane coupling agent are performed by a dry method, for example, ZWP particles, the fatty acid or a derivative thereof and the silane coupling agent are mixed in a mixing device such as a Henschel mixer or an air flow type pulverizer. Or the ZWP particles and a diluting solution obtained by diluting the fatty acid or its derivative and the silane coupling agent together with a solvent, and then drying such as heating as necessary. , Silane coupling agent is hydrolyzed and condensed. As a result, the desired Si-processed modified ZWP can be obtained. In the dry method, a modified ZWP is produced by using a mixture of ZWP particles coated with the fatty acid or its derivative and a silane coupling agent as it is. Therefore, the coating amount of the silane compound is the amount of the silane coupling agent charged. It is almost the same as the value theoretically calculated from the amount.

The Si-treated modified ZWP obtained by the method (B) is preferably further subjected to heat treatment after the coating treatment, regardless of whether the coating treatment is performed by a wet method or a dry method. The temperature of the heat treatment is preferably 70 ° C to 230 ° C, more preferably 100 ° C to 210 ° C, and the time of the heat treatment is preferably 30 minutes or more, more preferably 1 hour to 10 hours. The atmosphere in the heat treatment may be vacuum, an inert gas atmosphere, or an air atmosphere. By performing the heat treatment, the coating layer existing on the surface of the ZWP particles has a dense structure, and the ion elution from the modified ZWP in the presence of water is further suppressed. As a result, it is possible to obtain a modified ZWP having further excellent performance as a negative thermal expansion filler.

When the heat treatment is performed during the production of the Si-treated modified ZWP, the temperature of the heat treatment is particularly equal to or higher than the melting point of the fatty acid or its derivative and lower than the decomposition point of the fatty acid or its derivative. preferable. By treating at such a heating temperature, the coating layer existing on the surface of the ZWP particles has a more dense structure, and the ion elution from the modified ZWP in the presence of water is further suppressed.

The silane coupling agent is preferably a hydrophobic one, for example, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, aminosilane, γ-amino. Propyltriethoxysilane, N- (2-aminoethyl) 3-aminopropyltrimethoxysilane, N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane, hexamethyldisilazane, trimethylsilane, Trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, benzyldimethylchlorosilane, methyltrimethoxysilane, methyltriethoxysilane, isobutyltrimethoxysilane, dimethyldimethoxysilane, dimethyi Rudiethoxysilane, trimethylmethoxysilane, hydroxypropyltrimethoxysilane, phenyltrimethoxysilane, n-butyltrimethoxysilane, n-hexadecyltrimethoxysilane, n-octadecyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane , Γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-chloropropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ- Examples thereof include mercaptopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, and aminofluorinesilane.

The modified ZWP of the present invention obtained through the above steps is a negative heat for producing a low thermal expansion material in a dry state such as powder as it is or in a wet state in which the powder is dispersed in a solvent. It can be suitably used as an expansion filler.

Further, the negative thermal expansion filler of the present invention can be manufactured into a polymer composition by mixing the negative thermal expansion filler and a polymer compound. This polymer composition is a material whose coefficient of thermal expansion is suppressed due to the high negative thermal expansion of the modified ZWP.

The polymer compound used in the polymer composition of the present invention is not particularly limited, but is preferably a resin having a positive thermal expansion property. Examples of such resin include rubber, polyolefin resin, polycycloolefin resin, polystyrene resin, ABS resin, polyacrylate resin, polyphenylene sulfide resin, phenol resin, polyamide resin, polyimide resin, epoxy resin, silicone resin, polycarbonate resin. , Polyethylene resin, polypropylene resin, polyethylene terephthalate resin (PET resin), polyvinyl chloride resin and the like. These can be used alone or in combination.

The content of the negative thermal expansion filler in the polymer composition can be appropriately changed depending on the type of the polymer compound used and the use and purpose of the material to be produced, but is preferable for the polymer composition. Is 1% to 90% by volume. Similarly, the content of the polymer compound in the polymer composition is preferably 10% by volume to 99% by volume with respect to the polymer composition.

The polymer composition may further contain additives in addition to the negative thermal expansion filler and the polymer compound. As the additives, for example, antioxidants, heat stabilizers, ultraviolet absorbers, lubricants, releasing agents, dyes, colorants including pigments, flame retardants, crosslinking agents, softeners, dispersants, curing agents, polymerization initiators, Inorganic fillers and the like can be mentioned. The content of the additive is preferably 10% by volume to 90% by volume with respect to the polymer composition.

The polymer composition of the present invention can be produced by a known method. For example, when a curable resin is used as the polymer compound, a negative thermal expansion filler, a curable resin (or a prepolymer) and, if necessary, an additive are mixed at the same time to form a molded body, or a kind of resin component. In addition, there may be mentioned, for example, a method of previously mixing with a negative thermal expansion filler and, if necessary, an additive to form a mixture, and then mixing the mixture with a curable resin (or prepolymer) to form a molded body.

Further, when using a thermoplastic resin as the polymer compound, a method of melt-mixing the negative thermal expansion filler and the thermoplastic resin with an extruder to form a molded body, or the negative thermal expansion filler and the thermoplastic resin in a solid state. Examples thereof include a method of forming a mixed mixture into a molded product using an injection molding machine.

In the polymer composition of the present invention thus produced, the coefficient of thermal expansion is effectively suppressed by the high negative thermal expansion property of the modified ZWP used as the negative thermal expansion filler, and it is difficult for deformation due to heat to occur. It becomes a material. Further, since the amount of ions eluted from the modified ZWP used as the negative thermal expansion filler is small, it can be preferably used as a material for precision instruments such as a sealing material for electronic parts.

Hereinafter, the present invention will be described by way of examples, but the present invention is not limited to these examples.

<Preparation of zirconium phosphate tungstate particles (ZWP particles)>
(1. ZWP particle sample 1)
15 parts by mass of commercially available tungsten trioxide (WO ₃ ; average particle diameter 1.2 μm) was placed in a beaker, 84 parts by mass of pure water was further added, and 1 part by mass of polycarboxylic acid ammonium salt was added as a dispersant to disperse. It was a liquid. This dispersion was stirred for 120 minutes at room temperature (25 ° C.) using a three-one motor stirrer to prepare a 15 mass% slurry containing tungsten trioxide. The average particle size of the solid content in the slurry was 1.2 μm.

Then, zirconium hydroxide and an 85 mass% phosphoric acid aqueous solution were made into a slurry at room temperature (25 ° C.) so that the Zr: W: P molar ratio in the slurry became 2.00: 1.00: 2.00. The reaction solution was added. Using this reaction solution, reaction was carried out at room temperature (25 ° C.) for 2 hours with stirring. After the completion of the reaction, the total amount of the reaction liquid was dried at 200 ° C. for 24 hours in the atmosphere to obtain a reaction precursor. As a result of X-ray diffraction analysis of the obtained reaction precursor, only the diffraction peak of tungsten trioxide was observed.

Subsequently, the obtained reaction precursor was fired in the atmosphere at 950 ° C. for 2 hours to obtain white ZWP particle sample 1 as a fired product. When X-ray diffraction analysis was performed on the obtained ZWP particle sample 1, the sample 1 was single-phase Zr ₂ (WO ₄ ) (PO ₄ ) ₂ . Table 1 shows the average particle size and the BET specific surface area of ZWP particle sample 1. In addition, as a result of observation with a scanning electron microscope, the particle shape of the obtained ZWP particle sample 1 was crushed as shown in FIG.

(2. ZWP particle sample 2)
15 parts by mass of commercially available tungsten trioxide (WO ₃ ; average particle diameter 1.2 μm) was placed in a beaker, and 84 parts by mass of pure water was further added to obtain a dispersion liquid. This dispersion was stirred at room temperature (25 ° C.) for 120 minutes to prepare a 15 mass% slurry containing tungsten trioxide. The average particle size of the solid content in the slurry was 1.2 μm.

Then, zirconium hydroxide, 85 mass% phosphoric acid aqueous solution, and water so that the molar ratio of Zr: W: P: Mg in the slurry is 2.00: 1.00: 2.00: 0.1. Magnesium oxide and room temperature (25 ° C.) were added to the slurry to prepare a reaction solution. The reaction solution was heated to 80 ° C. and reacted for 4 hours with stirring. Thereafter, 1 part by mass of polycarboxylic acid ammonium salt was added as a dispersant to the reaction solution after the reaction was completed, and zirconia beads having a diameter of 0.5 mm were stirred with a media stirring type bead mill (manufactured by Ashizawa Finetech Co., Ltd., LMZ2) and wet-milled at 2000 rpm for 15 minutes. The average particle size of the solid content in the reaction liquid after the wet pulverization was 0.3 μm.

Next, the reaction liquid after wet pulverization was supplied to a spray dryer set at 220 ° C. at a supply rate of 2.4 L / h to obtain a reaction precursor. As a result of X-ray diffraction analysis of the obtained reaction precursor, only the diffraction peak of tungsten trioxide was observed.

Finally, the obtained reaction precursor was fired in the air at 960 ° C. for 2 hours to obtain white ZWP particle sample 2 as a fired product. When the obtained ZWP particle sample 2 was subjected to X-ray diffraction analysis, the sample 2 was single-phase Zr ₂ (WO ₄ ) (PO ₄ ) ₂ . Table 1 shows the average particle size and BET specific surface area of ZWP particle sample 2. As a result of observation with a scanning electron microscope, the particle shape of the obtained ZWP particle sample 2 was spherical as shown in FIG.

(Example 1)
50 g of ZWP particle sample 1 and 0.25 g (0.5% by mass) of stearic acid (melting point: 62 ° C. to 72 ° C.) were pulverized by an air flow type pulverizer (Sein Enterprise Co., AO jet mill). The mixture was mixed into a powder mixture, and the mixture was heat-treated at 100 ° C. for 30 minutes to obtain a modified ZWP in which the surface of ZWP particles was coated with a fatty acid. The modified ZWP was crushed particles. The conditions of the air flow type pulverizer were as follows: powder feed rate: 3 g / min, pusher pressure: 0.6 MPa, jet pressure: 0.6 MPa.

(Example 2)
A modified ZWP in which the surface of ZWP particles was coated with fatty acid was obtained by the same method as in Example 1 except that the powder mixture of ZWP particle sample 1 and stearic acid was heated at 200 ° C. for 30 minutes. The modified ZWP was crushed particles.

(Example 3)
50 g of ZWP particle sample 1, 0.25 g (0.5% by mass) of stearic acid (melting point: 62 ° C. to 72 ° C.), and 0.25 g (0.5% by mass) of silane coupling agent (γ- (Glycidoxypropyltrimethoxysilane) is pulverized and mixed by an air flow type pulverizer (AO jet mill manufactured by Seishin Enterprise Co., Ltd.) into a powder mixture, and the mixture is heat-treated at 200 ° C. for 30 minutes to prepare ZWP particles. A modified ZWP having the surface thereof coated with a fatty acid and a silane compound was obtained. The conditions of the airflow type pulverizer were the same as in Example 1. The modified ZWP was crushed particles.

(Example 4)
50 g of ZWP particle sample 2, 0.25 g (0.5% by mass) of stearic acid (melting point: 62 ° C. to 72 ° C.), and 0.25 g (0.5% by mass) of silane coupling agent (γ- Glycidoxypropyltrimethoxysilane) was added and mixed at 20000 rpm for 1 minute with a mixer (lab mixer: Labo Milser) to obtain a powder mixture, and the mixture was heat-treated at 200 ° C. for 30 minutes to obtain ZWP. A modified ZWP in which the surface of the particles was coated with a fatty acid and a silane compound was obtained. The modified ZWP was spherical particles.

(Example 5)
50 g of ZWP particle sample 1 and 0.25 g (0.5% by mass) of zinc stearate (melting point: 128 ° C. to 140 ° C.) were pulverized and mixed by the airflow type pulverizer to obtain a powder mixture, and the mixture was prepared. Heat treatment was performed at 200 ° C. for 30 minutes to obtain a modified ZWP in which the surface of ZWP particles was coated with a fatty acid derivative. The conditions of the airflow type pulverizer were the same as in Example 1. The modified ZWP was crushed particles.

(Comparative Examples 1 and 2)
Only ZWP particle sample 1 was used as Comparative Example 1, and only ZWP particle sample 2 was used as Comparative Example 2. That is, each comparative example uses only ZWP particles, and the surface of the particles is not coated with a fatty acid, its derivative or a silane compound.

(Comparative example 3)
Example 3 except that 50 g of ZWP particle sample 1 and 0.25 g (0.5% by mass) of silane coupling agent (γ-glycidoxypropyltrimethoxysilane) were used and no heat treatment was performed. A modified ZWP was obtained in the same manner as in. In this comparative example, the fatty acid or its derivative is not used, and the surface of the ZWP particles is coated with only the silane compound. The modified ZWP was crushed particles.

<Evaluation of physical properties>
(Evaluation of thermal expansion coefficient of powder)
The particles obtained in Examples and Comparative Examples were heated with an XRD device (Ultima IV manufactured by Rigaku Corporation) having a temperature raising function at a temperature raising rate of 20 ° C./min from 25 ° C. to a target temperature of 100 ° C. Ten minutes after reaching the target temperature, the lattice constants of the sample with respect to the a-axis, the b-axis, and the c-axis were measured. Then, the target temperatures were sequentially raised to 200 ° C., 300 ° C., and 400 ° C., and the lattice constants for the a-axis, b-axis, and c-axis of the sample at each temperature were measured in the same manner as in the above method. The obtained lattice volume change (rectangular solid) was linearly converted to obtain the thermal expansion coefficient (ppm / ° C.) (see J. Mat. Sci., (2000) 35, pp. 2451-2454). The results are shown in Table 2.

(Evaluation of the amount of eluted ions)
1 g of the particles obtained in Examples and Comparative Examples was added to 70 mL of pure water to prepare a test solution. The test solution was heated at 85 ° C. for 1 hour, cooled to room temperature (25 ° C.), and tested with pure water. The liquid was adjusted to 100 mL. After this test solution was allowed to stand for 24 hours, the test solution was subjected to solid-liquid separation by filtration, and the total Zr ion amount, the total W ion amount, and the total P ion amount per 100 mL of the filtrate were measured by an ICP emission spectrometer. The results are shown in Table 2.

As shown in Table 2, the modified ZWP of each example has the same level of negative thermal expansion coefficient as the particles of the comparative example, while suppressing the elution of ions from the particles. I understand. It can also be seen that particularly in Examples 2 and 5 in which the temperature of the heat treatment is high and in Examples 3 and 4 in which the silane compound is further coated, the elution of ions from the particles is significantly suppressed.

(Examples 6 to 10)
The modified ZWPs obtained in Examples 1 to 5 were used as negative thermal expansion fillers to produce polymer compositions. Specifically, 5.8 g of a negative thermal expansion filler and 4.2 g of an epoxy resin (Mitsubishi Chemical jER807, epoxy equivalent 160 to 175) as a polymer compound were mixed with a vacuum mixer (Awatori Kentaro ARV-310 manufactured by Shinky Co., Ltd.). ) Was mixed at a rotation speed of 2000 rpm to prepare a 30% by volume paste.

Next, 100 μL of a curing agent (CUREZOL manufactured by Shikoku Kasei) was added to the paste, and the mixture was mixed at a rotation speed of 1500 rpm using the vacuum mixer and cured at 150 ° C. for 1 hour to obtain a desired polymer composition. Got When a cross section of the obtained polymer composition was observed by a scanning electron microscope image, it was found that the modified ZWP, which is a negative thermal expansion filler, was uniformly dispersed in the polymer composition in all Examples. It could be confirmed.

(Reference example 1)
In place of the modified ZWP, 3.3 g of spherical fused silica (average particle size 10 μm, linear expansion coefficient 5 × 10 ⁻⁷ / ° C.) was used as a negative thermal expansion filler to prepare a 30% by volume paste. The target polymer composition was obtained in the same manner as in Example 6. When the cross section of the obtained polymer composition was observed by a scanning electron microscope image, it was confirmed that the spherical fused silica particles were uniformly dispersed in the polymer composition.

<Evaluation of thermal expansion coefficient of composition>
The polymer compositions obtained in the examples and reference examples were cut into a rectangular parallelepiped of 5 mm × 5 mm × 10 mm to obtain a measurement sample. The coefficient of linear expansion of this measurement sample was measured at 30 ° C. to 120 ° C. at a temperature rising rate of 1 ° C./min using a thermomechanical analyzer (TMA; 4000SE manufactured by NETZSCH). The results are shown in Table 3.

As shown in Table 3, it is understood that the polymer composition of each example using the modified ZWP of the present invention as the negative thermal expansion filler has a low linear expansion coefficient and is hardly deformed by heat.

Claims (10)

1. Modified zirconium tungstate phosphate in which the surface of zirconium tungstate phosphate particles is coated with fatty acid or its derivative.
2. The modified zirconium phosphate tungstate according to claim 1, wherein the BET specific surface area of the particles is 0.1 m ² / g to 50 m ² / g.
3. The modified zirconium tungstate phosphate according to claim 1 or 2, wherein the particles have an average particle size of 0.02 µm to 50 µm.
4. The modified zirconium phosphate tungstate according to any one of claims 1 to 3, wherein the particles further contain a sub-component element.
5. The modified zirconium phosphate tungstate according to any one of claims 1 to 4, wherein a coating amount of the fatty acid or its derivative is 0.05% by mass to 30% by mass with respect to the particles.
6. When 1 g of modified zirconium tungstate phosphate was heat treated with 70 mL of water at 85 ° C. for 1 hour, then cooled to 25 ° C. and allowed to stand for 24 hours, the amount of zirconium ions in the water was 20 μg or less, and tungsten was used. The modified zirconium tungstate phosphate according to any one of claims 1 to 5, which has an ion amount of 400 µg or less and a phosphorus ion amount of 100 µg or less.
7. The modified zirconium phosphate tungstate according to any one of claims 1 to 6, wherein the fatty acid or its derivative is a fatty acid having 7 or more carbon atoms or its derivative.
8. The modified zirconium phosphate tungstate according to any one of claims 1 to 7, which is coated with a silane compound.
9. A negative thermal expansion filler comprising the modified zirconium tungstate phosphate according to any one of claims 1 to 8.
10. A polymer composition containing the negative thermal expansion filler according to claim 9 and a polymer compound.

Images