WO2023037930A1 - Negative thermal expansion material, method for producing same, and paste - Google Patents

Abstract

The purpose of the present invention is to provide a negative thermal expansion material comprising zirconium phosphotungstate, from which a paste having a suitable viscosity can be produced when propylene carbonate is used as a solvent. The present invention is a negative thermal expansion material characterized by comprising at least surface-modified zirconium phosphotungstate particles which comprise zirconium phosphotungstate particles and hydrogen peroxide present on the surfaces of the zirconium phosphotungstate particles.

Description

NEGATIVE THERMAL EXPANSION MATERIAL, MANUFACTURING METHOD AND PASTE THEREOF

The present invention relates to a negative thermal expansion material that has the property of shrinking with temperature rise, a method for producing the same, and a paste containing the negative thermal expansion material.

Many substances increase in length and volume due to thermal expansion when the temperature rises. On the other hand, there is also known a material exhibiting negative thermal expansion in which the volume decreases when heated (hereinafter sometimes referred to as "negative thermal expansion material"). It is known that materials exhibiting negative thermal expansion can be used with other materials to reduce the change in thermal expansion of the material with changes in temperature.

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 is -3.4 to -3.0 ppm/K in the temperature range of 0 to 400 ° C., and the negative thermal expansion is large, and the material exhibiting positive thermal expansion (hereinafter " By using it together with a positive thermal expansion material, it is possible to produce a low thermal expansion material (see, for example, Patent Documents 1 and 2).

The present inventors also previously proposed zirconium tungsdate phosphate useful as a negative thermal expansion material (Patent Documents 3 and 4).

A paste containing a negative thermal expansion material, a binder resin, and a flux material such as a low-melting-point glass is used, for example, for OELDs, FEDs, PDPs, FPDs such as LCDs, lighting devices using light-emitting elements such as OEL elements (OLEDs), and dye enhancement. Glass panels that make up electronic devices such as solar cells such as sensitive solar cells, packages for electronic components such as MEMS (Micro Electro Mechanical Systems) and optical devices, bulbs for lighting, glass members such as multi-layer glass, etc. It has been proposed to use it as a sealing material or sealing material.

Propylene carbonate and the like are often used as a solvent for sealing materials and sealing material pastes (see, for example, Patent Documents 5 to 7).

JP-A-2005-35840 JP-A-2015-10006 Japanese Unexamined Patent Application Publication No. 2020-2000 Japanese Patent No. 6105140 JP-A-2019-94250, paragraph 0050 JP-A-2021-35895, paragraph 0054 JP 2018-90434, paragraph 0067

However, in the preparation of a sealing material using zirconium phosphate tungstate as a negative thermal expansion material, the viscosity of the paste tends to be low when propylene carbonate is used as the solvent, and a paste with a suitable viscosity is obtained. Also, the binder resin, solvent, or positive thermal expansion material mixed with the negative thermal expansion material has various properties, and phosphoric acid having various surface characteristics suitable for the properties. There is also a demand for development of a negative thermal expansion material containing zirconium tungstate.

Accordingly, it is an object of the present invention to provide a negative thermal expansion material containing zirconium phosphate tungstate that provides a paste having an appropriate viscosity when propylene carbonate is used as a solvent.

As a result of intensive research in view of the above-mentioned circumstances, the present inventors have found that (1) zirconium phosphate tungstate particles are brought into contact with hydrogen peroxide and phosphorus oxoacid to stably peroxidize the particle surface. surface-modified zirconium tungstate phosphate particles in which hydrogen is present; (3) By dispersing surface-modified zirconium tungstate phosphate particles with low affinity for propylene carbonate in propylene carbonate, a paste with high viscosity can be obtained. , completed the present invention.

That is, the first invention provided by the present invention is a surface-modified phosphoric acid comprising at least zirconium tungstate phosphate particles and hydrogen peroxide present on the surface of the zirconium tungstate phosphate particles. A negative thermal expansion material characterized by containing zirconium tungstate particles.

The second invention to be provided by the present invention is a contacting step of contacting zirconium tungstate phosphate particles with hydrogen peroxide and phosphorus oxoacid to obtain surface-modified zirconium tungstate phosphate particles. A method for producing a negative thermal expansion material, characterized by comprising:

A third invention provided by the present invention is a paste characterized by including the negative thermal expansion material of the first invention.

According to the present invention, it is possible to provide a negative thermal expansion material containing zirconium tungstate phosphate, which gives a paste having an appropriate viscosity when propylene carbonate is used as a solvent.

The present invention will be described below based on its preferred embodiments.
The negative thermal expansion material of the present invention is a surface-modified zirconium tungstate phosphate particle comprising at least zirconium tungstate phosphate particles and hydrogen peroxide present on the surface of the zirconium tungstate phosphate particles. A negative thermal expansion material comprising: That is, the negative thermal expansion material of the present invention includes surface-modified zirconium tungstate phosphate particles, and the surface-modified zirconium tungstate phosphate particles are composed of at least zirconium tungstate phosphate particles, hydrogen peroxide, consists of

The zirconium tungstate phosphate particles according to the negative thermal expansion material of the present invention are particles whose particle surfaces are modified by the presence of hydrogen peroxide and phosphorus oxoacid on the particle surfaces.
That is, the zirconium tungstate phosphate particles of the negative thermal expansion material of the present invention are raw material particles (hereinafter also referred to as raw material ZWP particles) that are brought into contact with hydrogen peroxide and phosphorus oxoacid.

The zirconium tungstate phosphate particles (raw material ZWP particles) of the negative thermal expansion material of the present invention are granular zirconium tungstate phosphate. Zirconium tungstate phosphate is represented by the following general formula (1).
_Zrx ( _WO4 ) _y ( _PO4 ) _z (1)
(Wherein, x is 1.7 ≤ x ≤ 2.3, preferably 1.8 ≤ x ≤ 2.2, 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.)

In order to improve the dispersibility and filling characteristics, the raw material ZWP particles contain elements other than P, W, Zr and O, which are elements contained in the zirconium phosphate tungstate represented by the general formula (1) ( Hereinafter, this is also referred to as "subcomponent element".) is preferably contained.

Examples of subcomponent elements include alkali metal elements such as Li, Na and K, alkaline earth metal elements such as Mg, Ca, Sr and Ba, Ti, V, Cr, Mn, Fe, Co, Ni, 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 , other metal elements other than transition metals such as Pb and Bi, metalloid elements such as B, Si, Ge, Sb and Te, non-metal elements such as S, halogen elements such as F, Cl, Br and I, etc. mentioned. One or more of these elements may be contained in the raw material ZWP particles. In order to further improve the dispersibility and filling characteristics, the raw material ZWP particles preferably contain at least one subcomponent element of Mg, Al and V. In addition, the thermal expansion coefficient is It is more preferable that the raw material ZWP particles contain Mg and/or Al as subcomponent elements in terms of facilitating suppression.

The content of the subcomponent element in the raw material ZWP particles is preferably It is 0.1 to 3.0% by mass, more preferably 0.2 to 2.0% by mass. When two or more subcomponent elements are included, the content of the subcomponent elements is calculated based on the total mass of the subcomponent elements. The content of subcomponent elements is measured by a powder press method, a molten glass bead method, or the like, using a measuring device such as a fluorescent X-ray analyzer.

When the raw material ZWP particles contain both Mg and Al as subcomponent elements, the negative thermal expansion property and the dispersibility and filling characteristics in the positive thermal expansion material can be further improved. The content of Al element in the raw material ZWP particles is preferably 100 to 6000 ppm by mass, more preferably 1000 to 5000 ppm by mass. In addition, the content of the Mg element in the raw material ZWP particles is preferably higher than that of the raw material ZWP particles in terms of having a practical linear expansion coefficient and being able to further improve dispersibility and filling characteristics. is 0.10 to 3.0% by mass, more preferably 0.22 to 2.0% by mass.

Raw material ZWP particles are obtained by reacting a zirconium source, a tungsten source, a phosphorus source and, if necessary, a subcomponent element source. The method for producing the raw material ZWP particles is not particularly limited. For example, (i) a method of mixing a reaction accelerator such as zirconium oxoate of phosphorus, tungsten oxide and MgO in a wet ball mill and then firing the resulting mixture ( For example, see 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 oxoate of phosphorus are wet-mixed, and then the resulting mixture is A method of firing (see, for example, JP-A-2015-10006), (iii) a method of firing a mixture containing zirconium oxide, tungsten oxide, and ammonium dihydrogen oxoate of phosphorus (for example, Materials Research Bulletin, 44 (2009) , p.2045-2049), (iv) calcining a mixture of a tungsten compound, an amorphous compound containing phosphorus and zirconium, and optionally added auxiliary component element sources as a reaction precursor. (See, for example, International Publication No. 2017/061402 pamphlet).

In addition, the BET specific surface area of the raw material ZWP particles is preferably 0.1 to 50 m 2 /g, more preferably 0.1 to 50 m ² /g, in terms of ease of handling when using the negative thermal expansion material of the present invention as a filler for a positive thermal expansion material. is 0.1 to 20 m ² /g, and the average particle size of the raw material ZWP particles is preferably 0.02 to 50 μm, more preferably 0.5 to 30 μm. In addition, the average particle diameter of the raw material ZWP particles is obtained by observing any 100 raw material ZWP particles using a scanning electron microscope, measuring the maximum length of each particle, and calculating the arithmetic average value of the raw material ZWP particles. It is obtained as the average particle diameter of the particles. At this time, the maximum length means the longest length among line segments crossing the two-dimensional projection image of the particle.

The particle shape of the raw material ZWP particles is not particularly limited. Hereinafter, this is also referred to as “crushed”.), or a combination thereof, but the particle shape of the raw material ZWP particles has good fluidity and is easy to uniformly mix and disperse in the positive thermal expansion material. A spherical shape is preferable in that it becomes

The negative thermal expansion material of the present invention contains surface-modified zirconium phosphate tungstate particles. In the surface-modified zirconium tungstate phosphate particles, hydrogen peroxide is present on the surface of the zirconium tungstate phosphate particles (particles of raw material ZWP particles).

In the negative thermal expansion material of the present invention, the amount of hydrogen peroxide present is 0.01 to 1.5 parts by mass, preferably 0.03 to 1.0 parts by mass, with respect to 100.0 parts by mass of raw material ZWP. When the amount of hydrogen peroxide present in the negative thermal expansion material of the present invention is within the above range, the surface of the raw material ZWP particles is efficiently coated with hydrogen peroxide.

In the surface-modified zirconium tungstate phosphate particles of the present invention, the hydrogen peroxide present on the surface was left at room temperature (25 ° C.) in a closed container for 20 days or more, and then filtered in the water elution test described later. Hydrogen peroxide contained in the filtrate can be stably present on the particle surface by detecting hydrogen peroxide test paper (manufactured by Merck, product name Quantofix Peroxide 25). It is preferable from the viewpoint that the thermal expansion material has excellent storage stability.

In the negative thermal expansion material of the present invention, from the viewpoint of making the negative thermal expansion material excellent in storage stability, the surface-modified zirconium tungstate phosphate particles are zirconium tungstate phosphate particles (particles of raw material ZWP particles). It is preferable that the oxoacid of phosphorus is present together with hydrogen peroxide on the surface of .

A phosphorus oxoacid refers to a compound having a structure in which a hydroxyl group (--OH) and an oxy group (=O) are bonded to a phosphorus atom. Phosphorus oxoacids include phosphoric acid (H ₃ PO ₄ ), phosphonic acid (H ₃ PO ₃ ), phosphinic acid (H ₃ PO ₂ ), pyrophosphoric acid (H ₄ P ₂ O ₇ ), polyphosphoric acid, and the like. be done. Among these, phosphoric acid is preferable as the phosphorus oxoacid because it is easy to handle and available at low cost.

In the negative thermal expansion material of the present invention, the amount of phosphorus oxoacid present is 0.005 to 2.0 parts by mass, preferably 0.02 to 1.8 parts by mass, relative to 100.0 parts by mass of raw material ZWP. . When the abundance of the phosphorus oxoacid in the negative thermal expansion material of the present invention is within the above range, the surface of the raw material ZWP particles is efficiently coated with the phosphorus oxoacid.

Regarding the abundance ratio of hydrogen peroxide and phosphorus oxoacid in the negative thermal expansion material of the present invention, the phosphorus oxoacid is 10.0 to 200.0 parts by mass with respect to 100.0 parts by mass of hydrogen peroxide, It is preferably 20.0 to 180.0 parts by mass. Since the abundance ratio of hydrogen peroxide and phosphorus oxo acid is within the above range, a paste having a more preferable viscosity can be obtained when propylene carbonate is used as a solvent for a paste containing a negative thermal expansion material. preferable.

Examples of the surface-modified zirconium tungstate phosphate particles according to the negative thermal expansion material of the present invention include contact products of zirconium tungstate phosphate particles (raw material ZWP particles) with hydrogen peroxide and phosphorus oxoacid. .

The method of bringing the raw material ZWP particles into contact with hydrogen peroxide and phosphorus oxoacid is not particularly limited. For example, (a) a solution containing hydrogen peroxide and a solution containing phosphorus oxoacid are mixed. (b) a method of contacting the raw material ZWP particles with a solution containing hydrogen peroxide and phosphorus oxoacid; and the like.

The negative thermal expansion material of the present invention preferably has an Rsp value of 0.15 or less, particularly preferably 0.05 to 0.15, which is obtained from the following formula (1) using propylene carbonate as a dispersion medium. When the value of Rsp obtained from the following formula (1) is within the above range, it becomes easy to adjust the viscosity of the paste in which the negative thermal expansion material is dispersed in propylene carbonate to an appropriate viscosity.

Calculation formula (1):
Rsp = (Rav/Rb) - 1 (1)
In formula (1), Rav is the reciprocal of the NMR relaxation time when pulse NMR measurement is performed with the negative thermal expansion material dispersed in propylene carbonate. Rb is the reciprocal of the NMR relaxation time when the pulse NMR measurement is performed without dispersing the negative thermal expansion material in the propylene carbonate.

The value of Rsp is known to be an index representing the affinity and wettability to the solvent that is the dispersion medium (for example, JP 2019-67590, WO2018/116890, WO2020/091000 pamphlet etc.). A large Rsp value indicates that the solvent has a high affinity for the dispersion medium and excellent wettability.

The raw material ZWP particles have a value of Rsp greater than 0.15, which is obtained from the above formula (1) using propylene carbonate as a dispersion medium. On the other hand, since the negative thermal expansion material of the present invention has a smaller Rsp than the raw material ZWP particles, it is considered that even if propylene carbonate is used as a solvent, a paste having an appropriate viscosity can be obtained.

In the propylene carbonate dispersion viscosity test, the dispersion viscosity when the negative thermal expansion material of the present invention is mixed and dispersed in propylene carbonate is preferably 20 to 100 MPa·s, particularly preferably 20 to 80 MPa·s. When the dispersion viscosity in the propylene carbonate dispersion test is within the above range, the paste containing the negative thermal expansion material has an appropriate viscosity. In addition, in the present invention, the propylene carbonate dispersion viscosity test is performed by the following method. 20.0 g of the negative thermal expansion material of the present invention is added to 6.0 g of propylene carbonate, and mixed for 10 minutes at a rotation speed of 2000 rpm using a mixer (for example, Awatori Mixer ARV-310 manufactured by Thinky Co., Ltd.). The negative thermal expansion material of the present invention is dispersed in carbonate, and the viscosity of the resulting mixed dispersion is measured with a viscometer (for example, tuning fork viscometer SV-10 manufactured by A&D).

In the water elution test, the hydrogen peroxide elution concentration of the negative thermal expansion material of the present invention is preferably 0.5 to 10 mass ppm. When the hydrogen peroxide elution concentration in the water elution test is within the above range, the paste containing the negative thermal expansion material has an appropriate viscosity. In addition, in this invention, a water elution test is performed by the following method. First, 4.0 g of the negative thermal expansion material of the present invention is added to 10.0 mL of pure water, stirred and mixed at room temperature (25° C.) for 1 minute, and then allowed to stand at room temperature (25° C.). After 20 hours, the supernatant was filtered through a membrane filter with a diameter of 0.5 μm, and the obtained filtrate was analyzed with a hydrogen peroxide test paper (manufactured by Merck, product name: Quantofix Peroxide 25). Measure the hydrogen concentration. The hydrogen peroxide concentration of the filtrate was evaluated by comparing it with a color sample in which the hydrogen peroxide concentration was changed at intervals of 0.5 mass ppm, 2 mass ppm, 5 mass ppm, 10 mass ppm and 25 mass ppm. done.

On the surface of the surface-modified zirconium tungstate phosphate particles, in addition to hydrogen peroxide and phosphorus oxoacid, tungstic acid, phosphotungstic acid, etc. may be adsorbed for the purpose of enhancing the modification effect. good.

Since the negative thermal expansion material of the present invention is mainly composed of zirconium phosphate tungstate particles, it has negative thermal expansion properties. In the negative thermal expansion material of the present invention, hydrogen peroxide and phosphorus oxoacid are chemically adsorbed on the surface of the zirconium tungstate phosphate particles, so the particle surface state of the zirconium tungstate phosphate particles is modified, and the affinity between the solvent, especially propylene carbonate, and the particle surface of the zirconium phosphate tungstate particles is lowered. As a result, when the negative thermal expansion material of the present invention is mixed and dispersed in a solvent, particularly propylene carbonate, the resulting paste has a high viscosity. Furthermore, in the negative thermal expansion material of the present invention, the interaction of hydrogen peroxide, the oxoacid of phosphorus, and the zirconium tungstate phosphate on the surface of the zirconium tungstate phosphate particles causes hydrogen peroxide to form on the surface of the zirconium tungstate phosphate particles. can exist stably in Therefore, in the negative thermal expansion material of the present invention, the modified state of the particle surface of the zirconium tungstate phosphate particles by the hydrogen peroxide and the oxoacid of phosphorus is maintained.

Next, a method for manufacturing the negative thermal expansion material of the present invention will be described.
The method for producing a negative thermal expansion material of the present invention comprises a contacting step of contacting zirconium tungstate phosphate particles with hydrogen peroxide and phosphorus oxoacid to obtain surface-modified zirconium tungstate phosphate particles. It is a method for producing a negative thermal expansion material characterized by the following.

The contacting step in the method for producing a negative thermal expansion material of the present invention is a step of bringing zirconium phosphate tungstate particles (raw material ZWP particles) into contact with hydrogen peroxide and phosphorus oxoacid. The zirconium tungstate phosphate particles (raw material ZWP particles) and phosphorus oxoacid in the contact step are the same as the zirconium tungstate phosphate particles (raw material ZWP particles) and phosphorus oxoacid in the negative thermal expansion material of the present invention. be.

In the contacting step, the method of contacting the zirconium tungstate phosphate particles with hydrogen peroxide and phosphorus oxoacid is not particularly limited. For example, (a) hydrogen peroxide and an aqueous solution of phosphorus oxoacid and (b) a method of contacting the raw material ZWP particles with a solution containing hydrogen peroxide and phosphorus oxoacid. Among these, the method (b) is preferable because the process can be simplified.

As the method of (a), (a1) the raw material ZWP particles are first brought into contact with a solution containing hydrogen peroxide, and then the contact product of the raw material ZWP particles and hydrogen peroxide is recovered, and then the recovered raw material A method of contacting a contact product of ZWP particles and hydrogen peroxide solution with a solution containing phosphorus oxoacid, (a2) first contacting the raw material ZWP particles with a solution containing phosphorus oxoacid, and then contacting the raw material ZWP (a3) A method of collecting a contact product of the particles and the phosphorus oxoacid, and then bringing a solution containing hydrogen peroxide into contact with the collected raw ZWP particles and the phosphorus oxoacid contact product, (a3) to the raw ZWP particles; A method of first contacting a solution containing hydrogen peroxide and then contacting the contact product of the raw material ZWP particles and the hydrogen peroxide solution with a solution containing phosphorus oxo acid without recovering the contact product. , (a4) After first contacting the raw material ZWP particles with a solution containing phosphorus oxoacid, the contact material of the raw material ZWP particles and the phosphorus oxoacid is then subjected to peroxide without recovering the contact material. A method of contacting a solution containing hydrogen can be mentioned.

The hydrogen peroxide and phosphorus oxoacid used in the contacting step are not particularly limited as long as they are industrially available. Hydrogen peroxide and phosphorus oxoacids may also be used as aqueous solutions.

The solution containing hydrogen peroxide and phosphorus oxoacid according to the method (b) is an aqueous solution in which hydrogen peroxide and phosphorus oxoacid are dissolved in a water solvent. The water solvent may be water alone or a mixed solvent of water and a hydrophilic solvent.

The content of hydrogen peroxide in the solution containing hydrogen peroxide and phosphorus oxoacid according to the method (b) is preferably 10.0 to 50.0% by mass, particularly preferably 20.0 to 40.0. % by mass. When the content of hydrogen peroxide in the solution containing hydrogen peroxide and the oxoacid of phosphorus is within the above range, it is preferable in terms of good workability and efficient contact treatment.

The content of the phosphorus oxoacid in the solution containing hydrogen peroxide and the phosphorus oxoacid according to the method (b) is preferably 1.0 to 40.0% by mass, particularly preferably 5.0 to 30.0% by mass. It is 0% by mass. When the content of the phosphorus oxoacid in the solution containing hydrogen peroxide and the phosphorus oxoacid is within the above range, it is preferable in terms of good workability and efficient contact treatment.

The content ratio of hydrogen peroxide and phosphorus oxoacid in the solution containing hydrogen peroxide and phosphorus oxoacid according to the method (b) is as follows: It is preferably 70.0 to 130.0 parts by mass, particularly preferably 80.0 to 120.0 parts by mass. When the content ratio of hydrogen peroxide and phosphorus oxoacid in the solution containing hydrogen peroxide and phosphorus oxoacid is within the above range, it is preferable in terms of good workability and efficient contact treatment. .

In the method (b), the raw material ZWP particles are brought into contact with a solution containing hydrogen peroxide and phosphorus oxoacid. and a method of mixing.

In the method (b), when the raw ZWP particles are brought into contact with a solution containing hydrogen peroxide and phosphorus oxoacid, the amount ratio of the raw ZWP particles and hydrogen peroxide is Hydrogen peroxide is preferably 0.01 to 1.5 parts by mass, particularly preferably 0.03 to 1.0 parts by mass. When the amount ratio of the raw material ZWP particles and hydrogen peroxide is within the above range, the surfaces of the raw material ZWP particles are efficiently coated with hydrogen peroxide. In addition, in the amount ratio of the raw material ZWP particles and hydrogen peroxide, the amount of hydrogen peroxide does not refer to the amount of the hydrogen peroxide solution, but to the amount of hydrogen peroxide itself.

In the method (b), when the raw material ZWP particles are brought into contact with a solution containing hydrogen peroxide and phosphorus oxoacid, the amount ratio of the raw material ZWP particles and the phosphorus oxoacid is set to 100.0 parts by mass of the raw material ZWP particles. On the other hand, the phosphorus oxoacid is preferably 0.005 to 2.0 parts by weight, particularly preferably 0.02 to 1.8 parts by weight. When the amount ratio of the raw material ZWP particles and the phosphorus oxoacid is within the above range, the surfaces of the raw material ZWP particles are efficiently coated with the phosphorus oxoacid. In the quantitative ratio of the raw material ZWP particles to the hydrogen peroxide, the amount of the phosphorus oxoacid does not refer to the amount of the phosphorus oxoacid solution, but to the amount of the phosphorus oxoacid itself.

In the method (b), a solution containing hydrogen peroxide and phosphorus oxoacid is added to 100.0 parts by weight of raw material ZWP particles, preferably 0.01 to 2.5 parts by weight, particularly preferably 0.01 part by weight. By mixing up to 2.0 parts by mass, the contact treatment can be performed efficiently with good workability, and the material after the contact treatment can be used as it is as a negative thermal expansion material without the need for a particular drying treatment. It is preferable that

The solution containing hydrogen peroxide according to method (a) is an aqueous solution in which hydrogen peroxide is dissolved in an aqueous solvent, and the solution containing phosphorus oxoacid is an aqueous solution in which phosphorus oxoacid is dissolved in an aqueous solvent. is. The water solvent may be water alone or a mixed solvent of water and a hydrophilic solvent.

The content of hydrogen peroxide in the solution containing hydrogen peroxide according to method (a) is preferably 10.0 to 50.0% by mass, particularly preferably 20.0 to 40.0% by mass. When the content of hydrogen peroxide in the solution containing hydrogen peroxide is within the above range, it is preferable in terms of good workability and efficient contact treatment.

The content of the phosphorus oxoacid in the solution containing the phosphorus oxoacid according to the method (a) is preferably 1.0 to 40.0% by mass, particularly preferably 5.0 to 30.0% by mass. be. When the content of the phosphorus oxoacid in the solution containing the phosphorus oxoacid is within the above range, it is preferable in terms of good workability and efficient contact treatment.

The ratio of the hydrogen peroxide in the solution containing hydrogen peroxide and the phosphorus oxoacid in the solution containing phosphorus oxoacid according to the method (a) is, per 100.0 parts by mass of the phosphorus oxoacid, Hydrogen is preferably 70.0 to 130.0 parts by weight, particularly preferably 80.0 to 120.0 parts by weight. When the ratio of the hydrogen peroxide in the solution containing hydrogen peroxide and the oxoacid of phosphorus in the solution containing the oxoacid of phosphorus is within the above range, the contact treatment can be performed efficiently with good workability. point is preferable.

In the method (a), the raw material ZWP particles are brought into contact with a solution containing hydrogen peroxide or a solution containing phosphorus oxoacid. and a method of mixing a solution containing an acid.

In the method (a), the amount ratio of the raw material ZWP particles and hydrogen peroxide when the raw material ZWP particles are brought into contact with a solution containing hydrogen peroxide is 100.0 parts by mass of raw material ZWP particles. , preferably 0.01 to 1.5 parts by mass, particularly preferably 0.03 to 1.0 parts by mass. When the amount ratio of the raw material ZWP particles and hydrogen peroxide is within the above range, the surfaces of the raw material ZWP particles are efficiently coated with hydrogen peroxide. In addition, in the amount ratio of the raw material ZWP particles and hydrogen peroxide, the amount of hydrogen peroxide does not refer to the amount of the hydrogen peroxide solution, but to the amount of hydrogen peroxide itself.

In the method (a), the amount ratio of the raw material ZWP particles and the phosphorus oxoacid when the raw material ZWP particles are brought into contact with the solution containing the phosphorus oxoacid is The oxoacid is preferably 0.005 to 2.0 parts by weight, particularly preferably 0.02 to 1.8 parts by weight. When the amount ratio of the raw material ZWP particles and the phosphorus oxoacid is within the above range, the surfaces of the raw material ZWP particles are efficiently coated with the phosphorus oxoacid. In the quantitative ratio of the raw material ZWP particles to the hydrogen peroxide, the amount of the phosphorus oxoacid does not refer to the amount of the phosphorus oxoacid solution, but to the amount of the phosphorus oxoacid itself.

In the method (a), a solution containing hydrogen peroxide and a solution containing phosphorus oxoacid are added to 100.0 parts by weight of the raw material ZWP particles, and the total of them is preferably 0.05 to 5.0 mass. Parts, particularly preferably 0.1 to 4.5 parts by mass, are mixed, so that the contact treatment can be performed efficiently with good workability. It is preferable in that it can be used as it is as a negative thermal expansion material.

In the methods (a) and (b), the contact product of zirconium tungsdate phosphate particles with hydrogen peroxide and phosphorus oxoacid may be powder, slurry or paste depending on the amount of solution added. It can be in the form of a liquid or a solid. Therefore, as the mixing treatment for contacting the zirconium tungsdate phosphate particles with hydrogen peroxide and the oxoacid of phosphorus, a conventional wet or dry mixing treatment is appropriately selected depending on the properties of the resulting mixture. You should go.

The device used for wet mixing is not particularly limited as long as a uniform mixture (contact product) can be obtained. Equipment such as mills, sand grind mills, attritors and intensive agitators may be mentioned. The wet mixing process is not limited to the mixing process by mechanical means exemplified above.

As for the dry mixing method, it is preferable to use mechanical means because a uniform mixture can be obtained. The device used for dry mixing is not particularly limited as long as a homogeneous mixture can be obtained. Blenders, V-type mixers, conical blenders, jet mills, cosmomizers, paint shakers, bead mills, ball mills and the like can be mentioned. At the laboratory level, a home-use mixer or manual work is sufficient.

In the methods (a) and (b), the temperature at which the zirconium tungstate phosphate particles are brought into contact with hydrogen peroxide and phosphorus oxoacid is not particularly limited, but is often 10 to 50°C. It is preferably 20 to 40°C. In the case of method (a), the temperature at which the solution containing phosphorus oxoacid or the solution containing hydrogen peroxide is brought into contact with the raw material ZWP particles is shown.

In methods (a) and (b), the time at which the zirconium phosphate tungstate particles are contacted with hydrogen peroxide and the oxoacid of phosphorus is not critical in the process, often 10 minutes. Above, preferably in 15 to 60 minutes, a satisfactory negative thermal expansion material can be obtained. In the case of the method (a), the time is shown when the raw material ZWP particles are brought into contact with the solution containing phosphorus oxoacid or the solution containing hydrogen peroxide.

In the methods (a) and (b), when the zirconium tungstate phosphate particles are brought into contact with hydrogen peroxide and phosphorus oxoacid, the solution containing hydrogen peroxide and/or phosphorus oxoacid contains the necessary Depending on the requirements, tungstic acid, phosphotungstic acid, or the like may be contained for the purpose of enhancing the effect of modification.

Thus, in the contacting step, the zirconium tungstate phosphate particles are brought into contact with the oxoacid of hydrogen peroxide and phosphorus, whereby the zirconium tungstate phosphate particles are brought into contact with the oxoacid of hydrogen peroxide and phosphorus. Surface-modified zirconium tungsdate phosphate particles are obtained.

In the method for producing a negative thermal expansion material of the present invention, a suitable range of the amount of the solution containing hydrogen peroxide and phosphorus oxoacid added, or the amount of the solution containing hydrogen peroxide and the solution containing phosphorus oxoacid added In the preferred range, the amount of the solution containing hydrogen peroxide and the oxoacid of phosphorus added to the raw material ZWP particles is small, or the amount of the solution containing the solution containing hydrogen peroxide and the solution containing the oxoacid of phosphorus is small. Therefore, the properties of the contact material obtained by bringing the raw material ZWP particles into contact with the method (a) or (b) basically maintains the powder state without drying.

Therefore, in the method for producing a negative thermal expansion material of the present invention, after performing the contacting step, drying may be performed as necessary. Further, in the method for producing a negative thermal expansion material of the present invention, pulverization, crushing, classification, etc. may be further performed as necessary. Further, when the drying treatment is performed, the entire contact product of the zirconium tungstate phosphate particles, the hydrogen peroxide and the oxoacid of phosphorus may be dried as it is.

Then, in the method for producing a negative thermal expansion material of the present invention, by performing the contacting step, or after performing the contacting step, drying treatment, pulverization, crushing, classification, etc. are performed as necessary, A negative thermal expansion material is obtained.

When the raw material ZWP particles are brought into contact with only hydrogen peroxide, the surface of the ZWP particles is difficult to modify because the hydrogen peroxide on the surface of the particles decomposes over time after the contact. On the other hand, by bringing the raw material ZWP particles into contact with the phosphorus oxoacid in addition to the hydrogen peroxide, the hydrogen peroxide and the phosphorus oxoacid are present in a stable state on the ZWP particle surface, and the ZWP particles Since the surface of ZWP particles is modified by chemical adsorption on the surface, it is considered that a paste having an appropriate viscosity can be obtained even when propylene carbonate is used as a solvent.

The negative thermal expansion material of the present invention can be used in the form of powder or paste. When used as a paste, the negative thermal expansion material of the present invention can be suitably used in a paste state containing a solvent and, if necessary, a binder resin. That is, the paste of the present invention is characterized by containing the negative thermal expansion material of the present invention.

As the solvent used for the paste, one commonly used in the technical field is used. For example, N,N'-dimethylformamide, ethylene glycol, dimethyl sulfoxide, dimethyl carbonate, propylene carbonate, butyrolactone, caprolactone, N-methyl-2-pyrrolidone, butyl carbitol acetate, propylene glycol dicetate, α-terpineol, α-terpineol, γ-butyl lactone, tetralin, ethyl acetate, isoamyl acetate, diethylene glycol monoethyl ether, diethylene glycol monoethyl ether acetate, benzyl alcohol, toluene, 3-methoxy-3-methylbutanol, triethylene glycol monomethyl ether, dipropylene Glycol monomethyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monobutyl ether, etc., may be mentioned, and these may be used singly or in combination of two or more. Also, even if the negative thermal expansion material of the present invention uses propylene carbonate as a solvent, a paste having an appropriate viscosity can be obtained. Therefore, in the paste of the present invention, propylene carbonate is preferably used as a solvent.

In addition, the paste of the present invention can contain a binder resin as needed. As the binder resin, one commonly used in the technical field is used. Specific examples of the binder resin include celluloses such as nitrocellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, oxyethyl cellulose, benzyl cellulose, and propyl cellulose; polyalkylene carbonates such as polyethylene carbonate and polypropylene carbonate; methyl (meth)acrylate; Ethyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, (meth) acrylic acid resins such as 2-hydroxyethyl (meth) acrylate, polyethylene glycol derivatives, polymethyl styrene, etc. These may be used singly or in combination of two or more.

The content of the negative thermal expansion material in the paste of the present invention is not particularly limited, but in many cases it is 1 to 99% by volume, preferably 10 to 90% by volume.

A paste containing the negative thermal expansion material of the present invention and further containing a flux material is suitably used, for example, as a sealing material paste or a sealing material paste.

As the flux material to be contained in the paste of the present invention, a low-melting-point glass can be mentioned, and a general one in the technical field is used. For example, PbO—B ₂ O ₃ system, PbO—SiO ₂ —B ₂ O ₃ system, Bi ₂ O ₃ —B ₂ O ₃ system, Bi ₂ O ₃ —SiO ₂ —B ₂ O ₃ system, SiO ₂ —B _{2O3 - Al2O3 system} , _{SiO2 - B2O3 -} BaO system _{, SiO2 - B2O3} -CaO system, ZnO- _B2O3 - _Al2O3 system, ZnO- _SiO2- B ₂ O ₃ system, P ₂ O ₅ system, SnO—P ₂ O ₅ system, V ₂ O ₅ -P ₂ O ₅ system, V ₂ O ₅ -Mo ₂ O ₃ system, and V ₂ O ₅ -P ₂ O ₅ —TeO ₂ and the like are mentioned.

Although the content of the flack material in the paste of the present invention is not particularly limited, it is often 10 to 90% by volume, preferably 15 to 90% by volume.

When used as a sealing material paste, when a sealing material containing a flux material and a negative thermal expansion material is used, the flux material is 60 to 90% by volume, and the negative thermal expansion material of the present invention is 10 to 40% by volume. It is preferable to prepare the paste so that the content of the flux material and the negative thermal expansion material is 0.1 to 40% by mass of the binder resin and 5 to 40% by mass of the solvent.

Further, when used as a sealing material paste for multi-layer glass, the sealing material paste can be used by incorporating glass beads known in the relevant field.

The paste of the present invention can further contain additives such as antifoaming agents, dispersants, coloring pigments, and thixotropy-imparting agents known in the art, if necessary.

In addition, the negative thermal expansion material of the present invention uses the negative thermal expansion material as it is as a powder and incorporates it into the positive thermal expansion material to form a composite material. It can also be used as an expansion or low thermal expansion material.

Examples of the positive thermal expansion material containing the negative thermal expansion material of the present invention include various organic compounds and inorganic compounds.

Examples of the organic compound include rubber, polyolefin, polycycloolefin, polystyrene, ABS, polyacrylate, polyphenylene sulfide, phenol resin, polyamide resin, polyimide resin, epoxy resin, silicone resin, polycarbonate resin, polyethylene resin, polypropylene resin. , polyethylene terephthalate resin (PET resin) and polyvinyl chloride resin.

Examples of the inorganic compound include metals, alloys, silicon dioxide, graphite, sapphire, various glasses, concrete materials, and various ceramic materials.

Among these, the positive thermal expansion material is preferably at least one selected from metals, alloys, glasses, ceramics, rubbers and resins. In the composite material according to the present invention, the addition amount of the negative thermal expansion material of the present invention can adopt a general addition amount in the technical field.

The present invention will be described below with reference to examples, but the present invention is not limited to these.

(Preparation of raw material ZWP particles)
15 parts by mass of commercially available tungsten trioxide (WO ₃ ; average particle size: 1.2 μm) was placed in a beaker, and 84 parts by mass of pure water was further added.
A 15% by mass slurry containing tungsten trioxide was prepared by stirring at room temperature (25° C.) for 120 minutes. The average particle size of the solid content in the slurry was 1.2 µm.
Next, zirconium hydroxide, 85% by mass phosphoric acid aqueous solution and magnesium hydroxide were added to the slurry so that the molar ratio of Zr:W:P:Mg in the slurry was 2.00:1.00:2.00:0. After addition at room temperature (25° C.) so as to give 0.10, the temperature was raised to 80° C. and the reaction was carried out with stirring for 4 hours.
After completion of the reaction, 1 part by mass of polycarboxylic acid ammonium salt was charged as a dispersant, and while stirring the slurry, it was supplied to a media-stirring bead mill charged with zirconia beads with a diameter of 0.5 mm, mixed for 15 minutes, and wet pulverized. did The average particle size of the solid content in the slurry after wet pulverization was 0.3 μm.
Then, the slurry 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 of the obtained reaction precursor, only diffraction peaks of tungsten trioxide were observed. When analyzed by FT-IR, it had an infrared absorption peak at 950 to 1150 cm ^-1 and the maximum value of the infrared absorption peak during this period appeared at 1042 cm ^-1 .
Next, the obtained reaction precursor was subjected to a firing reaction in the atmosphere at 1050° C. for 2 hours to obtain a white fired product.
X-ray diffraction analysis of the fired product obtained revealed that the fired product was single-phase Zr ₂ (WO ₄ )(PO ₄ ) ₂ . These were used as raw material ZWP particles.

(Preparation of solution containing hydrogen peroxide and phosphoric acid)
A 30.0% by mass hydrogen peroxide aqueous solution and an 85.0% by mass phosphoric acid aqueous solution were mixed at a weight ratio of 10:2 to prepare a solution containing hydrogen peroxide and phosphoric acid.

(Example 1)
100.0 g of the raw material ZWP particles prepared above were placed in a zippered plastic bag. Then, 0.40 g of the solution containing hydrogen peroxide and phosphorus oxoacid prepared above was added thereto and mixed manually for 10 minutes at room temperature (25° C.) to obtain a contact product, 25° C.) and left for 20 days in an airtight container, and this was used as a negative thermal expansion material sample.

(Example 2)
100.0 g of the raw material ZWP particles prepared above were placed in a zippered plastic bag. Then, 0.60 g of the solution containing hydrogen peroxide and phosphorus oxoacid prepared above was added thereto and mixed manually for 10 minutes at room temperature (25° C.) to obtain a contact product, 25° C.) and left for 20 days in an airtight container, and this was used as a negative thermal expansion material sample.

(Example 3)
100.0 g of the raw material ZWP particles prepared above were placed in a zippered plastic bag. Then, 0.80 g of the solution containing hydrogen peroxide and phosphorus oxoacid prepared above was added thereto and mixed manually for 10 minutes at room temperature (25° C.) to obtain a contact product, 25° C.) and left for 20 days in an airtight container, and this was used as a negative thermal expansion material sample.

(Comparative example 1)
The raw material ZWP particles prepared above were used as they were, and were used as negative thermal expansion material samples.

(Comparative example 2)
100.0 g of the raw material ZWP particles prepared above were placed in a zippered plastic bag. Next, 0.33 g of ion-exchanged water was added to this, and mixed manually for 10 minutes at room temperature (25° C.) to obtain a mixture, which was used as a negative thermal expansion material sample.

(Comparative Example 3)
100.0 g of the raw material ZWP particles prepared above were placed in a zippered plastic bag. Next, 0.40 g of a 30.0% by mass aqueous hydrogen peroxide solution is added, mixed manually for 10 minutes at room temperature (25° C.) to obtain a mixture, and placed in a sealed container at room temperature (25° C.) for 20 days. This was used as a negative thermal expansion material sample.

(Measurement of linear thermal expansion coefficient)
<Preparation of ceramic molding>
0.5 g of the negative thermal expansion material samples obtained in Examples and Comparative Examples and 0.05 g of a binder (SpectroBlend 44 μm Powder) were mixed in a mortar for 5 minutes, and the entire amount was filled in a 3 mm×20 mm mold. Then, using a hand press, a powder compact was produced by compacting at a pressure of 2 tons. The resulting powder compact was fired in an electric furnace at 1100° C. for 2 hours in an air atmosphere to obtain a ceramic compact of zirconium phosphate tungstate.
<Measurement of thermal expansion coefficient>
The coefficient of linear thermal expansion of the ceramic molding was measured with a thermomechanical measuring device (TMA4000SE manufactured by NETZSCH JAPAN). The measurement conditions were a nitrogen atmosphere, a load of 10 g, and a temperature range of 50°C to 250°C.

(Measurement of Rsp Value Using Propylene Carbonate as Dispersion Medium)
1.0 g of a negative thermal expansion material sample was added to 20.0 ml of pyropyrene carbonate, and subjected to ultrasonic dispersion treatment (130 W) for 20 minutes to obtain a dispersion liquid. Then, the relaxation time at 25° C. was measured with a pulse NMR apparatus (manufactured by Nihon Luft Co., Ltd.), and the value of Rsp was obtained from the following formula (1).
Rsp = (Rav/Rb) - 1 (1)
In formula (1), Rav is the reciprocal of the NMR relaxation time when pulse NMR measurement is performed with 1.0 g of the negative thermal expansion material sample dispersed in 20.0 ml of propylene carbonate, and Rb is the propylene carbonate. It is the reciprocal of the NMR relaxation time when pulse NMR measurement is performed with a blank state in which the negative thermal expansion material is not dispersed in 20.0 ml.

(Propylene carbonate dispersion viscosity test)
20.0 g of a negative thermal expansion material sample and 6.0 g of propylene carbonate were weighed and mixed in a mixer (Awatori Mixer ARV-310, manufactured by Thinky Corporation) at a rotation speed of 2000 rpm for 10 minutes to obtain a mixed dispersion of 30 Vol%. created a paste.
The viscosity of this mixed dispersion (paste) was measured with a tuning fork viscometer SV-10 (manufactured by A&D Co., Ltd.).

(Water elution test)
4.0 g of a negative thermal expansion material sample was added to 10.0 mL of pure water, stirred and mixed at room temperature (25° C.) for 1 minute, and then allowed to stand at room temperature (25° C.). After 20 hours, the supernatant was filtered through a 0.5 μm membrane filter, and the obtained filtrate was analyzed with hydrogen peroxide test paper (manufactured by Merck Ltd., product name: Quantofix Peroxide 25) to determine the concentration of hydrogen peroxide in the filtrate. was analyzed. To determine the hydrogen peroxide concentration of the filtrate, the hydrogen peroxide concentration was changed at intervals of 0.5 mass ppm, 2 mass ppm, 5 mass ppm, 10 mass ppm and 25 mass ppm. It was done by

As is clear from Table 2, the negative thermal expansion materials obtained in the examples give moderately viscous pastes when mixed and dispersed in propylene carbonate.

Claims (11)

1. A negative heat characterized by containing surface-modified zirconium tungstate phosphate particles comprising at least zirconium tungstate phosphate particles and hydrogen peroxide present on the surface of the zirconium tungstate phosphate particles. expansion material.
2. The negative thermal expansion material according to claim 1, wherein the surface-modified zirconium tungstate phosphate particles are a contact product of zirconium tungstate phosphate particles, hydrogen peroxide and phosphorus oxoacid.
3. 2. The surface-modified zirconium tungstate phosphate particles are obtained by mixing zirconium tungstate phosphate particles with a solution of hydrogen peroxide and phosphorus oxoacid. negative thermal expansion material.
4. The negative thermal expansion material according to claim 2 or 3, wherein the phosphorus oxoacid is phosphoric acid.
5. The negative thermal expansion material according to any one of claims 1 to 4, characterized in that the zirconium tungstate phosphate further contains an accessory element.
6. The negative thermal expansion material according to claim 5, wherein the subcomponent element is one or more selected from metallic elements of Mg, V and Al.
7. 7. The negative thermal expansion material according to any one of claims 1 to 6, wherein the value of Rsp obtained from the following formula (1) using propylene carbonate as a dispersion medium is 0.15 or less.
   Rsp = (Rav/Rb) - 1 (1)
   (In formula (1), Rav is the reciprocal of the NMR relaxation time when the pulse NMR measurement is performed with the negative thermal expansion material dispersed in propylene carbonate. Rb is the negative thermal expansion material dispersed in propylene carbonate. It is the reciprocal of the NMR relaxation time when pulse NMR measurement is performed in the state without
8. A method for producing a negative thermal expansion material, comprising a contacting step of contacting zirconium tungstate phosphate particles with hydrogen peroxide and an oxoacid of phosphorus to obtain surface-modified zirconium tungstate phosphate particles.
9. 9. The production of the negative thermal expansion material according to claim 8, wherein the contacting step is performed by mixing the zirconium tungstate phosphate particles with a solution containing hydrogen peroxide and phosphorus oxoacid. Method.
10. The method for producing a negative thermal expansion material according to claim 8 or 9, characterized in that the zirconium phosphate tungstate further contains an accessory element.
11. A paste comprising the negative thermal expansion material according to any one of claims 1 to 7.