JPS5853660B2 - Manufacturing method of filler - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a calcium carbonate filler that has excellent gloss, dispersibility, and affinity for various materials.

Calcium carbonate powder can be used as a fibrous agent for paper, a viscosity improver for pasty or solid substances, an extender for various materials, a gelling agent,
It is widely used as a reinforcing agent for plastics.

However, by crushing naturally occurring heavy calcium carbonate,
If it is added to an organic substance such as a resin as it is, it will result in poor dispersion due to the poor affinity between the two substances and the non-uniformity and secondary agglomeration of the powder particles of heavy calcium carbonate. There are problems such as reduced mechanical performance and limited applications.

To solve these problems, attempts have been made to improve the particle size of calcium carbonate powder, such as adjusting the particle size to make it uniform, and treating the particle surface to increase its affinity with organic substances. For example, a surfactant, metal soap, fatty acid, etc. are added to a calcium hydroxide emulsion, carbon dioxide gas is introduced to make the calcium carbonate raw, and this calcium carbonate is crushed during drying to produce surface-treated calcium carbonate powder. The manufacturing method includes adding calcium carbonate to an aqueous solution of an organic acid such as stearic acid or its salt, for example calcium stearate, mixing it, drying it and then pulverizing it.
Methods for obtaining surface-treated calcium carbonate powder have been proposed.

However, since these methods are based on treatment in an aqueous solution, they require steps such as removal of treated water and treatment residues, and re-grinding, resulting in complicated operations and low treatment efficiency. there were.

Another known method is to heat-react calcium carbonate powder and an organic carboxylic acid under anhydrous conditions to form a coating of a calcium salt of the organic carboxylic acid on the surface of the calcium carbonate powder particles. Since the surface of the calcium carbonate powder particles is directly coated with an organic carboxylic acid, the surface-treated calcium carbonate particles may become discolored, reducing their commercial value or making the particle shape non-uniform. When kneading with resin as a filler,
There were drawbacks such as decreased dispersibility and decreased surface gloss.

The present inventors have overcome these drawbacks and have efficiently and inexpensively produced particles with smooth surfaces, uniform particle sizes, and beautiful luster.
As a result of extensive research in order to produce a filler mainly composed of calcium carbonate, which has good affinity with organic substances such as resins and excellent dispersibility, we first treated calcium carbonate with an inorganic acid and then unsaturated it. It was discovered that a filler suitable for this purpose could be obtained by treatment with a carboxylic acid,
The present invention was made based on this knowledge.

That is, in the present invention, 0.2 to 5 parts by weight of an inorganic acid is added as an aqueous solution with a concentration of about 20 to 50 parts by weight to 100 parts by weight of heavy calcium carbonate powder, and then 100 parts by weight of heavy calcium carbonate powder is heated. The present invention provides a method for producing a filler, which comprises adding 0.3 to 5.0 parts by weight of an unsaturated carboxylic acid per part by weight and thoroughly mixing the mixture to form a coating on the surface of the powder particles.

In the present invention, as the heavy calcium carbonate, natural calcium carbonate is used which has been subjected to coarse crushing, medium crushing, and fine crushing processes to form a fine powder on the order of μ, or one which is in the process of being finely crushed.

In addition, as the inorganic acid added in a small amount in the present invention,
Any substance that can react with calcium carbonate may be used, and examples thereof include sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid.

These acids may be used alone or in combination of two or more.

In the present invention, the inorganic acid acts on the surface of the calcium carbonate powder particles, removes impurities present on the particle surface and causes coloration during heating, smoothes the particle surface, and makes the particles uniform and almost spherical. It is thought that it plays the role of forming a layer of calcium salt of an inorganic acid on the particle surface.

In the present invention, the inorganic acid is used as a low concentration aqueous solution of about 20 to 50% in order to fully exhibit the above effect, and the amount used depends on the type of inorganic acid and the particle size of the heavy calcium carbonate powder. , although it varies depending on the purpose of use as a filler, etc., 0.2 to 5 parts by weight per 100 parts by weight of heavy calcium carbonate (calculated as 100% inorganic acid),
It is preferably selected within the range of 0.3 to 3.0 parts by weight.

If the amount is less than this, the properties of the filler will not be sufficiently improved, and if the amount is greater than this, the properties of calcium carbonate will be impaired.

The heat treatment performed after adding the inorganic acid to heavy calcium carbonate is carried out by heating to about 80 to 110° C. while stirring well to ensure a uniform reaction.

The processing time is usually about 5 to 60 minutes.

The thus treated heavy calcium carbonate is then mixed with an unsaturated carboxylic acid to form an unsaturated fatty acid calcium salt layer on top of the inorganic acid calcium salt layer formed on the surface of the heavy calcium carbonate powder particles. A coating is formed.

As a result, the resulting filler has improved compatibility with organic substances such as resins, and has excellent affinity and dispersibility.

The unsaturated carboxylic acids used generally include a hydrocarbon moiety having one or more ethylenic double bonds and one
or an unsaturated carboxylic acid having 10 or less carbon atoms consisting of two or more carboxyl groups, such as acrylic acid,
Examples include methacrylic acid, crotonic acid, cinnamic acid, norbic acid, maleic acid, itaconic acid, glutaconic acid, and vinyl acetic acid.

These may be used alone or in combination of two or more.

These carboxylic acids can also be used in the form of anhydrides, such as maleic anhydride.

The amount of these unsaturated carboxylic acids to be used varies depending on the particle size of the calcium carbonate particles and the purpose of use as a filler, but it is 0.3 to 5 parts by weight per 100 parts by weight of heavy calcium carbonate.
．． 0 parts by weight, preferably 0.5 to 2 parts by weight.

Treatment with unsaturated carboxylic acid is carried out with sufficient stirring to ensure uniform reaction, and the treatment temperature is usually 20 to 20°C.
The temperature is 40°C.

Processing time is approximately 5-80 degrees.

The filler obtained by the present invention exhibits no coloration at all even when kneaded with resin etc., has a beautiful luster, has excellent affinity with organic substances and has excellent dispersibility, and can be used in a wide range of applications. Furthermore, the manufacturing method is simple and inexpensive, making it suitable for industrial implementation.

Next, the present invention will be explained in more detail with reference to Examples.

Example 100 parts by weight of heavy calcium carbonate powder (average particle size 1.6μ, specific surface area approximately 12X103-〆<y) was charged into a Henschel mixer, maintained at 100°C, and a predetermined amount of an inorganic acid with a predetermined concentration was added. After stirring at this temperature for 15 minutes,
A predetermined amount of unsaturated carboxylic acid was added and stirred at 40° C. for 60 minutes to produce a filler mainly composed of calcium carbonate.

The properties of the obtained filler are shown in the table below.

These fillers and polypropylene (Idemitsu Polypro J-750H manufactured by Idemitsu Petrochemical Co., Ltd., d=0.90 g/art
, MI=8) in a Banbury mixer at a resin temperature of 2.
The mixture was kneaded at 30° C. for 5 minutes to prepare a resin composition.

The resin composition thus obtained was molded using an injection molding machine (manufactured by Niigata Tekko Shinsei, 5N-160) at a resin temperature of 210° C. and a mold temperature of 500 G to create an ASTM standard test piece.

When various physical properties of the test piece thus obtained were measured, the results shown in the following table were obtained.

Measurement of each physical property was performed by the following method.

(1) I) H: Add 100ml of water to 5g of sample, stir well with a glass rod, leave for 1 hour, and remove the supernatant liquid.
H was measured.

(2) D, 0. P dispersibility; dioctyl phthalate 1
After adding 3 g of sample to 00M and leaving it for 24 hours, the apparent volume of sedimentation was measured.

(3) Specific surface area: Measured by air permeation method (ffl/9) using a Shimadzu powder specific surface area measuring device.

(4) Oil absorption: Using linseed oil, JIS-510
Measured according to 1.

(5) Whiteness: Measured by a comparison method using a standard body (MgO) of 100% using a Keratokken photoelectric white meter C-1 model blue filter.

(6) Tensile properties; according to ASTM D-638.

(7) Bending properties: Based on ASTM D-790.

(8) Izot impact resistance: Based on As TMD-256.

(9) Surface glossiness: According to ASTM D-523.

(10) Formability: vertical 150 mm, horizontal 2001 m,
The injection moldability was observed and evaluated when a box with a depth of 40 mm and a wall thickness of 4 mm was molded.

aυ Dispersibility: A film having a thickness of approximately 50 μm was formed by pressing, and the state of light transmission was evaluated visually.

The following inorganic acids were used.

H2SO4: Industrial sulfuric acid (concentration 94-95%, specific gravity 1.
83-1.84 g/ml) diluted 2 times with water.

H3PO4: Dilute industrial phosphoric acid (concentration 80-85%) twice with water.

H2SO4+H3PO4; Mix industrial sulfuric acid and industrial phosphoric acid in the same weight ratio and dilute to 2 times with water.

From this table, it can be seen that the filler beam of the present invention, 0. P, dispersibility;
The resin composition obtained by blending the filler of the present invention, which shows good values for specific surface area, oil absorption, and whiteness,
It can be seen that it has excellent mechanical properties, high gloss, and good moldability and dispersibility.

Claims (1)

[Scope of Claims] 1. 0.2 to 5 parts by weight of an inorganic acid is added as an aqueous solution with a concentration of about 20 to 50 φ to 100 parts by weight of heavy calcium carbonate powder, and after heat treatment, 100 parts by weight of heavy calcium carbonate powder is added. A method for producing a filler with good dispersibility, which comprises adding 0.3 to 5.0 parts by weight of an unsaturated carboxylic acid per part by weight and thoroughly mixing the mixture to form a coating on the surface of the powder particles. 2. The manufacturing method according to claim 1, wherein the inorganic acid is at least one selected from sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid. 3 Unsaturated carboxylic acid is acrylic acid, methacrylic acid,
At least one selected from crotonic acid, cinnamic acid, sorbic acid, maleic acid, glutaconic acid, and vinyl acetic acid
The manufacturing method according to claim 1, which is a seed.