JPH04370188A - Thixotropy imparter - Google Patents

Abstract

PURPOSE:To provide a thixotropy imparter composed of fibrous or needlelike magnesium oxysulfate in which defects such as bad dispersibility and unstable thixotropy are improved. CONSTITUTION:A thixotropic imparter is composed of fibrous or needlelike magnesium oxysulfate having the surface treated with a compound having at least one alcoholic hydroxyl group in the molecule, 0.5-50mum length, 0.05-1mum diameter and 10-300 aspect ratio (length/diameter).

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thixotropic agent comprising surface-treated fibrous or acicular magnesium oxysulfate.

0002

BACKGROUND OF THE INVENTION Rheology modifiers that adjust flow characteristics such as thickening and thixotropy are used in a wide range of fields such as various paints, coatings, adhesives, and sealants. Such rheology modifiers include modified castor oil derivatives that impart structural viscosity, polyolefin waxes, organic amides, urea compounds, finely divided silica, basic calcium sulfonate gels, organic microgels, nonaqueous dispersion resin particles, and amine-treated clay. etc.

[0003] Although asbestos has excellent properties of imparting thickening properties and thixotropy, it is said to be harmful to health. Further, JP-A-63-314250 discloses a thixotropy imparting agent comprising acicular calcium silicate crystals with a particle size of 10 to 150 μm.

Regarding the thickening properties of fibrous or acicular magnesium oxysulfate, gypsum and lime, No. 2
16, 337-339 (1988), it has been shown that, like asbestos, when added to water, epoxy resins, polyols that are raw materials for polyurethane resins, and asphalt, the viscosity increases. However, thixotropy is not mentioned.

Fibrous or acicular magnesium oxysulfate exhibits excellent thixotropy as described in Japanese Patent Application No. 2-123076.

[0006] Japanese Patent Application No. 2-123076 discloses that a mixture of fibrous or acicular magnesium oxysulfate and a liquid polymer exhibits thixotropy. In addition, in a mixture of fibrous or acicular magnesium oxysulfate, liquid polymer, and organic solvent, when the organic solvent is a polar solvent that is a compound having at least one alcoholic hydroxyl group or sulfur in the molecule, the thixotropy is significantly improved. However, in this case, the mixing ratio of the polar solvent and the fibrous or acicular magnesium oxysulfate is 1 to 100 parts by weight, preferably 5 parts by weight of the fibrous or acicular magnesium oxysulfate per 100 parts by weight of the polar solvent.
~50 parts by weight.

[0007]

[Problem to be solved by the invention] Patent application No. 2-12307
No. 6 states that fibrous or acicular magnesium oxysulfate has chemically active magnesium ions, alkaline hydroxyl groups, and sulfate ions, so when mixed with a liquid polymer, or with a liquid polymer, alcoholic hydroxyl groups or sulfur in the molecule. It has been shown that when mixed with a mixture of polar solvents, which is a compound having at least one compound, it imparts thixotropy to the resulting composition. However, since fibrous or acicular magnesium oxysulfate has high agglomeration and poor dispersibility, especially when mixed without using the above-mentioned polar solvent, fibrous or acicular magnesium oxysulfate may not be present in the liquid polymer. There was a problem with the presence of aggregates.

[0008] Another problem is that when the temperature of a composition of a liquid polymer or its mixture with a polar solvent and fibrous or acicular magnesium oxysulfate changes and the viscosity of the composition decreases, the thixotropy decreases. Ta.

The object of the present invention is to provide good dispersibility when fibrous or acicular magnesium oxysulfate is mixed in a liquid polymer or a liquid polymer and a polar solvent;
It is an object of the present invention to provide a thixotropy-imparting agent whose thixotropy does not decrease even when the temperature of the composition increases and the viscosity decreases.

0010

[Means for Solving the Problems] The above objects of the present invention are as follows:
Surface treated with a compound having at least one alcoholic hydroxyl group in the molecule, length 0.5 to 50 μm, diameter 0.5 μm.
05-1μm, aspect ratio (length/diameter) 10-30
This is achieved by using a thixotropic agent consisting of 0 fibrous or acicular magnesium oxysulfate.

Furthermore, the above object of the present invention is to provide a molecule having a length of 0.5 to 50 μm that has at least two alcoholic hydroxyl groups in its molecule and has been surface-treated with a compound having 2 or more carbon atoms.
, diameter 0.05-1 μm, aspect ratio (length/diameter)
This is more preferably achieved by a thixotropy imparting agent consisting of 10 to 300 fibrous or acicular magnesium oxysulfate.

Fibrous or acicular magnesium oxysulfate can be prepared by the method described in JP-A-1-126218, that is, by adding magnesium hydroxide or magnesium oxide having a BET specific surface area of 20 m2/g or less to an aqueous magnesium sulfate solution at a concentration of 25 m2/g or less. It can be suitably produced by a method of dispersing to a weight percent or less and then subjecting it to a hydrothermal reaction at a temperature of 100 to 300°C.

[0013] Furthermore, the method described in JP-A-1-41544 is used, that is, after dispersing magnesium sulfate and magnesium hydroxide or magnesium oxide so that the concentration thereof is 25% by weight or less, the dispersion is carried out at a temperature of 100 to 300°C. When producing fibrous or acicular magnesium oxysulfate by hydrothermal reaction, it can be suitably produced in the same manner as the above method by incorporating a surfactant into the hydrothermal reaction system.

The obtained fibrous or acicular magnesium oxysulfate has a powder X-ray diffraction spectrum of ASTM No. It is in good agreement with that of 7-415,
Typically, the ASTM No. It is thought that it can be expressed by the specific formula MgSO4.5Mg(OH)2.3H2O described in No. 7-415.

The general form of fibrous or acicular magnesium oxysulfate has a specific gravity of 2.0 to 2.5, a length (fiber length) of several microns to 1000 μm, and an apparent specific gravity of 0.
．． 05 to 0.3, it is an extremely bulky fibrous or needle-like substance, and its trade name is Moshyge (manufactured by Ube Industries, Ltd.).
It is distributed in the market as.

Fibrous or acicular magnesium oxysulfate has chemically active magnesium ions, alkaline hydroxyl groups, and sulfate ions, so when mixed with a liquid polymer, or with a liquid polymer, it has at least an alcoholic hydroxyl group or sulfur in the molecule. When mixed with a mixture of polar solvents, the compound imparts thixotropy to the resulting composition. However, since fibrous or acicular magnesium oxysulfate has high agglomeration and poor dispersibility, especially when mixed without using the above-mentioned polar solvent, fibrous or acicular magnesium oxysulfate may not be present in the liquid polymer. There was a problem in that the presence of aggregates led to a decrease in thixotropy.

[0017] Another problem is that when the temperature of the composition of the liquid polymer or its mixture with a polar solvent and fibrous or acicular magnesium oxysulfate changes and the viscosity of the composition decreases, the thixotropy decreases. Ta.

Therefore, even if fibrous or acicular magnesium oxysulfate is mixed with a liquid polymer or a mixture thereof with a polar solvent, the thixotropy does not decrease, and the thixotropy of the composition changes as the temperature of the composition changes. As a result of various studies on methods that would not cause the decrease, it was discovered that the above problems could be solved by treating the surface of fibrous or acicular magnesium oxysulfate with a compound having an alcoholic hydroxyl group, and the present invention was achieved.

[0019] The thixotropic effect when a liquid polymer and fibrous or acicular magnesium oxysulfate are mixed is thought to occur because the fibrous or acicular magnesium oxysulfate forms a network structure in the liquid polymer. . Compounds having alcoholic hydroxyl groups easily dissolve in liquid polymers, so treating the surface of fibrous or acicular magnesium oxysulfate with a compound having alcoholic hydroxyl groups prevents the aggregation of fibrous or acicular magnesium oxysulfate, It improves dispersion when mixed into a liquid polymer, and when a compound with an alcoholic hydroxyl group is dissolved in the liquid polymer, the surface of the fibrous or acicular magnesium oxysulfate returns to an active state, forming a network structure that exhibits thixotropy. It is thought that the formation of is facilitated and the thixotropy is increased.

Fibrous or acicular magnesium oxysulfate is usually produced by carrying out a hydrothermal reaction using magnesium hydroxide and sulfuric acid as raw materials, followed by filtration, washing and drying. The following two methods are suitable for treating the surface of oxysulfate with a compound having an alcoholic hydroxyl group. That is,

■ A method of adding water to the dehydrated cake of fibrous or acicular magnesium oxysulfate obtained after washing to form a slurry again, and adding a compound having an alcoholic hydroxyl group to this slurry;

0022
]■ This is a method in which a compound having an alcoholic hydroxyl group is added to a dehydrated cake of fibrous or acicular magnesium oxysulfate obtained after washing.

[0023] The surface of the fibrous or acicular magnesium oxysulfate is treated by such a method, and then, if necessary, it is filtered and dried to obtain the thixotropy imparting agent of the present invention.

The amount of the compound having an alcoholic hydroxyl group to be added to the fibrous or acicular magnesium oxysulfate is 0.1 to 20 parts by weight, preferably 1 to 5 parts by weight, per 100 parts by weight of the fibrous or acicular magnesium oxysulfate. Department.

Liquid polymers to which the thixotropy imparting agent of the present invention imparts thixotropy include, for example, epoxy resins, phthalate resins,
Amino alkyd resin, vinyl resin, polyurethane resin,
Unsaturated polyester resin and acrylic resin. These liquid polymers are commercially available in various organic solvents, namely methyl alcohol, ethyl alcohol, isopropyl alcohol, butyl alcohol, ethyl acetate, ethyl cellosolve, butyl cellosolve, acetone, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, petroleum ether, petroleum benzine. , gasoline, kerosene,
It is often used in combination with trichlorethylene, carbon tetrachloride, etc.

[0026] Fibrous or acicular magnesium oxysulfate suitable as a thixotropy imparting agent has a length of 0.5 to 50 mm.
μm, a diameter of 0.05 to 1 μm, and an aspect ratio (length/diameter) of 10 to 300. length is 5
If it exceeds 0 μm or the aspect ratio exceeds 300, the fibrous or acicular magnesium oxysulfate becomes entangled and does not exhibit sufficient effects.

The mixing ratio of the fibrous or acicular magnesium oxysulfate, which is the thixotropy-imparting agent of the present invention, and the liquid polymer depends on the type of the target liquid polymer, the presence or absence of an organic solvent, the type, and the desired degree of thixotropy. Although it is difficult to make a general statement because it varies depending on the type of polymer, it is usually 0.5 to 20 parts by weight, preferably 1 to 10 parts by weight, per 100 parts by weight of the liquid polymer.

Compounds having at least one alcoholic hydroxyl group in the molecule used in the present invention include ethanol, 1-propanol, 1-butanol, isobutyl alcohol, 1-pentanol, 3-pentanol, 2-
Methyl-1-butanol, 1-hexanol, 3-methyl-3-pentanol, 1-octanol, ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1, Examples include 5-pentanediol, glycerin, polyethylene glycol, and the like.

[0029]

[Examples] Table 1 shows the main properties of the liquid polymers used in the Examples and Comparative Examples of this specification.

[0030]

[Table 1]

Example 1 After adding fibrous or acicular magnesium oxysulfate seed crystals and magnesium hydroxide slurry to an aqueous magnesium sulfate solution and thoroughly dispersing them, the dispersion was placed in an autoclave at a temperature of 180°C and a pressure of 10 kg/kg. cm2・
A hydrothermal reaction was carried out at G for 2 hours.

After the reaction, the product was filtered and washed with water to obtain a dehydrated cake of fibrous or acicular magnesium oxysulfate having a water content of 77.6%. This dehydrated cake 112
Put g and 1500 g of water into a 3000 ml beaker, and use a homomixer (4C type manufactured by Tokushu Kika Kogyo Co., Ltd., the same applies hereinafter).
Dispersion treatment was carried out for 5 minutes. Next, an ethylene glycol aqueous solution prepared by adding 12 g of ethylene glycol to 500 g of water was added, and the surface was treated with a homomixer for 5 minutes. Furthermore, the dehydrated cake obtained by filtration and having a water content of 77.7% was dried at a temperature of 125° C. for 5 hours. This dried material was easily loosened and sieved through a 1.5 mm sieve.1.
Those that passed through a 5 mm sieve were used for the test. The fibrous or acicular magnesium oxysulfate thus obtained has a length of 5 to 20 μm and a diameter of 0.3 to 20 μm.
It was 0.7 μm.

Next, 15 g of the fibrous or acicular magnesium oxysulfate obtained in this way and 500 g of epoxy resin were placed in a tabletop kneader (Model PNV-1 manufactured by Irie Shokai Co., Ltd., hereinafter the same) and heated for 25 minutes. A mixture was prepared by heating to 0.degree. C. and mixing under reduced pressure for 1 hour. This mixture was taken out into a 500 ml beaker that had been preheated to 25°C, and the mixture was placed in a vacuum device heated to 25°C to reduce the pressure and remove air bubbles, and then the viscosity was measured using a B-type viscometer while heating at 25°C. . The results are shown in Table 2.

Examples 2 to 4 Fibers subjected to surface treatment by replacing ethylene glycol with 1,5-pentanediol (Example 2), glycerin (Example 3), or polyethylene glycol with an average molecular weight of 200 (Example 4) A mixture of fibrous or acicular magnesium oxysulfate and epoxy resin (2) was prepared in the same manner as in Example 1, except that acicular or acicular magnesium oxysulfate was used, and the viscosity was measured in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 1 After adding fibrous or acicular magnesium oxysulfate seed crystals and magnesium hydroxide slurry to an aqueous magnesium sulfate solution and thoroughly dispersing them, the dispersion was placed in an autoclave at a temperature of 180°C and a pressure of 10 kg/kg. cm2・
A hydrothermal reaction was carried out at G for 2 hours.

After the reaction, the product was filtered and washed with water to obtain a dehydrated cake of fibrous or acicular magnesium oxysulfate having a water content of 77.6%. This dehydrated cake 112
g and 1,500 g of water were placed in a 3,000 ml beaker, and dispersed for 5 minutes using a homomixer. Next, 500 g of water was added and the mixture was further dispersed for 5 minutes using a homomixer. Furthermore, the dehydrated cake obtained by filtration and having a water content of 77.6% was dried at a temperature of 125° C. for 5 hours. This dried material is easily loosened and sieved through a 1.5 mm sieve.
Those that passed through the sieve were used for the test. The shape of the obtained fibrous or acicular magnesium oxysulfate was 5 to 20 μm in length and 0.3 to 0.7 μm in diameter.

Next, 15 g of the fibrous or acicular magnesium oxysulfate thus obtained and 500 g of epoxy resin were placed in a tabletop kneader, heated to 25° C., and mixed for 1 hour under reduced pressure to form a mixture. Manufactured. This mixture was taken out into a 500 ml beaker that had been preheated to 25°C, and the mixture was placed in a vacuum device heated to 25°C to reduce the pressure and remove air bubbles, and then the viscosity was measured using a B-type viscometer while heating at 25°C. . The results are shown in Table 2.

Example 5 After adding fibrous or acicular magnesium oxysulfate seed crystals and magnesium hydroxide slurry to an aqueous magnesium sulfate solution and thoroughly dispersing them, the dispersion was placed in an autoclave at a temperature of 180°C and a pressure of 10 kg/kg. cm2・
A hydrothermal reaction was carried out at G for 2 hours.

After the reaction, the product was filtered and washed with water to obtain a dehydrated cake of fibrous or acicular magnesium oxysulfate having a water content of 77.6%. This dehydrated cake 112
g and 1,500 g of water were placed in a 3,000 ml beaker, and dispersed for 5 minutes using a homomixer. Next, add 12% of polyethylene glycol with an average molecular weight of 200 to 500g of water.
A polyethylene glycol aqueous solution prepared by adding g was added thereto, and the surface was treated with a homomixer for 5 minutes. Furthermore,
Filter the resulting dehydrated cake with a moisture content of 77.7% at a temperature of 1
It was dried at 25°C for 5 hours. Easily loosen this dried material,
The material was sieved using a 1.5 mm sieve, and the material that passed through the 1.5 mm sieve was used for the test. The fibrous or acicular magnesium oxysulfate thus obtained had a length of 5 to 20 μm and a diameter of 0.3 to 0.7 μm.

Next, 15 g of the fibrous or acicular magnesium oxysulfate thus obtained was placed in a tabletop kneader together with a mixed solution prepared by mixing 500 g of epoxy resin (1) and 100 g of ethyl alcohol. , heated to 25° C. and mixed under reduced pressure for 1 hour to prepare a mixture. This mixture was taken out into a 500 ml beaker that had been preheated to 25°C, and the mixture was placed in a vacuum device heated to 25°C to reduce the pressure and remove air bubbles, and then the viscosity was measured using a B-type viscometer while heating at 25°C. . Table 2 shows the results.
Shown below.

Comparative Example 2 After adding fibrous or acicular magnesium oxysulfate seed crystals and magnesium hydroxide slurry to an aqueous magnesium sulfate solution and thoroughly dispersing them, the dispersion was placed in an autoclave at a temperature of 180°C and a pressure of 10 kg/kg. cm2・
A hydrothermal reaction was carried out at G for 2 hours.

After the reaction, the product was filtered and washed with water to obtain a dehydrated cake of fibrous or acicular magnesium oxysulfate having a water content of 77.6%. This dehydrated cake 112
g and 1,500 g of water were placed in a 3,000 ml beaker, and dispersed for 5 minutes using a homomixer. Next, 500 g of water was added and the mixture was further dispersed for 5 minutes using a homomixer. Furthermore, the dehydrated cake obtained by filtration and having a water content of 77.6% was dried at a temperature of 125° C. for 5 hours. This dried material is easily loosened and sieved through a 1.5 mm sieve.
Those that passed through the sieve were used for the test. The shape of the obtained fibrous or acicular magnesium oxysulfate was 5 to 20 μm in length and 0.3 to 0.7 μm in diameter.

Next, 15 g of the fibrous or acicular magnesium oxysulfate thus obtained was placed in a tabletop kneader together with a mixed solution prepared by mixing 500 g of epoxy resin (1) and 100 g of ethyl alcohol. , heated to 25° C. and mixed under reduced pressure for 1 hour to prepare a mixture. This mixture was taken out into a 500 ml beaker that had been preheated to 25°C, and the mixture was placed in a vacuum device heated to 25°C to reduce the pressure and remove air bubbles, and then the viscosity was measured using a B-type viscometer while heating at 25°C. . Table 2 shows the results.
Shown below.

[0044]

[Table 2]

Examples 6 and 7 A mixture was produced in the same manner as in Example 4, except that epoxy resin ■ was replaced with epoxy resin ■ (Example 6) and epoxy resin ■ (Example 7). The viscosity was measured. The results are shown in Table 3.

Comparative Example 3 After adding fibrous or acicular magnesium oxysulfate seed crystals and magnesium hydroxide slurry to an aqueous magnesium sulfate solution and thoroughly dispersing them, the dispersion was placed in an autoclave at a temperature of 180°C and a pressure of 10 kg/kg. cm2・
A hydrothermal reaction was carried out at G for 2 hours.

After the reaction, the product was filtered and washed with water to obtain a dehydrated cake of fibrous or acicular magnesium oxysulfate having a water content of 77.6%. This dehydrated cake 112
g and 1,500 g of water were placed in a 3,000 ml beaker, and dispersed for 5 minutes using a homomixer. Next, 500 g of water was added and the mixture was further dispersed for 5 minutes using a homomixer. Furthermore, the dehydrated cake obtained by filtration and having a water content of 77.6% was dried at a temperature of 125° C. for 5 hours. This dried material is easily loosened and sieved through a 1.5 mm sieve.
Those that passed through the sieve were used for the test. The shape of the obtained fibrous or acicular magnesium oxysulfate was 5 to 20 μm in length and 0.3 to 0.7 μm in diameter.

Next, 15 g of the fibrous or acicular magnesium oxysulfate thus obtained and 500 g of epoxy resin were placed in a tabletop kneader, heated to 25° C., and mixed for 1 hour under reduced pressure to form a mixture. Manufactured. This mixture was taken out into a 500 ml beaker that had been preheated to 25°C, and the mixture was placed in a vacuum device heated to 25°C to reduce the pressure and remove air bubbles, and then the viscosity was measured using a B-type viscometer while heating at 25°C. . The results are shown in Table 3.

Comparative Example 4 After adding fibrous or acicular magnesium oxysulfate seed crystals and magnesium hydroxide slurry to an aqueous magnesium sulfate solution and thoroughly dispersing them, the dispersion was placed in an autoclave at a temperature of 180°C and a pressure of 10 kg/kg. cm2・
A hydrothermal reaction was carried out at G for 2 hours.

After the reaction, the product was filtered and washed with water to obtain a dehydrated cake of fibrous or acicular magnesium oxysulfate having a water content of 77.6%. This dehydrated cake 112
g and 1,500 g of water were placed in a 3,000 ml beaker, and dispersed for 5 minutes using a homomixer. Next, 500 g of water was added and the mixture was further dispersed for 5 minutes using a homomixer. Furthermore, the dehydrated cake obtained by filtration and having a water content of 77.6% was dried at a temperature of 125° C. for 5 hours. This dried material is easily loosened and sieved through a 1.5 mm sieve.
Those that passed through the sieve were used for the test. The shape of the obtained fibrous or acicular magnesium oxysulfate was 5 to 20 μm in length and 0.3 to 0.7 μm in diameter.

Next, 15 g of the fibrous or acicular magnesium oxysulfate thus obtained and 500 g of epoxy resin were placed in a tabletop kneader, heated to 25° C., and mixed for 1 hour under reduced pressure to form a mixture. Manufactured. This mixture was taken out into a 500 ml beaker that had been preheated to 25°C, and the mixture was placed in a vacuum device heated to 25°C to reduce the pressure and remove air bubbles, and then the viscosity was measured using a B-type viscometer while heating at 25°C. . The results are shown in Table 3.

Examples 8 and 9 After adding fibrous or acicular magnesium oxysulfate seed crystals and magnesium hydroxide slurry to an aqueous magnesium sulfate solution and thoroughly dispersing them, the dispersion was placed in an autoclave and heated at a temperature of 180°C and a pressure. 10kg/cm2・
A hydrothermal reaction was carried out at G for 2 hours.

After the reaction, the product was filtered and washed with water to obtain a dehydrated cake of fibrous or acicular magnesium oxysulfate having a water content of 77.6%. This dehydrated cake 112
g and 1,500 g of water were placed in a 3,000 ml beaker, and dispersed for 5 minutes using a homomixer. Next, a glycerin aqueous solution (Example 8) or a polyethylene glycol aqueous solution (Example 9) prepared by adding 12 g of glycerin (Example 8) or polyethylene glycol with an average molecular weight of 200 (Example 9) to 500 g of water was added. Then, surface treatment was performed for 5 minutes using a homomixer. Furthermore, the dehydrated cake with a moisture content of 77.7% obtained by filtration was heated at a temperature of 125°C for 5 minutes.
Dry for an hour. Easily loosen this dried material into 1.5mm pieces.
The material that passed through the 1.5 mm sieve was used for the test. The fibrous or acicular magnesium oxysulfate thus obtained had a length of 5 to 20 μm and a diameter of 0.3 to 0.7 μm.

Next, 15 g of the fibrous or acicular magnesium oxysulfate thus obtained and 500 g of epoxy resin were placed in a tabletop kneader, heated to 25° C., and mixed for 1 hour under reduced pressure. A mixture was prepared by heating the mixture to 0.degree. C. and mixing for 30 minutes. This mixture was taken out into a 500 ml beaker that had been previously heated to 55°C, and the mixture was placed in a vacuum device heated to 55°C to reduce the pressure and remove air bubbles, and then the viscosity was measured using a B-type viscometer while heating at 55°C. . The results are shown in Table 3.

Comparative Example 5 After adding fibrous or acicular magnesium oxysulfate seed crystals and magnesium hydroxide slurry to an aqueous magnesium sulfate solution and thoroughly dispersing them, the dispersion was placed in an autoclave at a temperature of 180°C and a pressure of 10 kg/kg. cm2・
A hydrothermal reaction was carried out at G for 2 hours.

After the reaction, the product was filtered and washed with water to obtain a dehydrated cake of fibrous or acicular magnesium oxysulfate having a water content of 77.6%. This dehydrated cake 112
g and 1,500 g of water were placed in a 3,000 ml beaker, and dispersed for 5 minutes using a homomixer. Next, 500 g of water was added and the mixture was further dispersed for 5 minutes using a homomixer. Furthermore, the dehydrated cake obtained by filtration and having a water content of 77.6% was dried at a temperature of 125° C. for 5 hours. This dried material is easily loosened and sieved through a 1.5 mm sieve.
Those that passed through the sieve were used for the test. The shape of the obtained fibrous or acicular magnesium oxysulfate was 5 to 20 μm in length and 0.3 to 0.7 μm in diameter.

Next, 15 g of the fibrous or acicular magnesium oxysulfate thus obtained and 500 g of epoxy resin were placed in a tabletop kneader, heated to 25° C., and mixed for 1 hour under reduced pressure. A mixture was prepared by heating the mixture to 0.degree. C. and mixing for 30 minutes. This mixture was taken out into a 500 ml beaker that had been previously heated to 55°C, and the mixture was placed in a vacuum device heated to 55°C to reduce the pressure and remove air bubbles, and then the viscosity was measured using a B-type viscometer while heating at 55°C. . The results are shown in Table 3.

[0058]

[Table 3]

[0059]

Effects of the Invention The present invention utilizes fibrous or acicular magnesium oxysulfate as a thixotropic composition by surface-treating it with a compound having at least one alcoholic hydroxyl group in the molecule and mixing it with a liquid polymer or the like. We have succeeded in solving the problems of poor dispersibility and unstable thixotropy when dispersing.

Claims (2)

[Claims] Claim 1: A molecule having a length of 0.5 and whose surface has been treated with a compound having at least one alcoholic hydroxyl group in the molecule.
A thixotropy imparting agent consisting of fibrous or acicular magnesium oxysulfate having a diameter of ~50 μm, a diameter of 0.05 to 1 μm, and an aspect ratio (length/diameter) of 10 to 300. 2. A thixotropic compound comprising the fibrous or acicular magnesium oxysulfate according to claim 1, which has at least two alcoholic hydroxyl groups in its molecule and has been surface-treated with a compound having two or more carbon atoms. agent.