JPS5835535B2 - Gypsum reinforced styrenic resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to styrenic resin compositions reinforced with acicular anhydrite.

Styrenic resins such as general purpose polystyrene and rubber-reinforced polystyrene are considered to be one of the general-purpose resins because they have advantages such as good moldability and light weight.

However, depending on the application, it may be necessary to modify mechanical strength, thermal expansion, permanent strain, etc.

In order to achieve such modification, a method has been proposed in which fibrous fillers such as glass fiber, asbestos, and carbon fibers, and amorphous fillers such as lucium carbonate and talc are added to styrenic resins.

The types of these fillers depend on the purpose of use of the material.
Amount is selected.

However, when amorphous fillers are blended with styrenic resins, the mechanical strength is not improved as much as expected, and when fibrous fillers are blended, the improvement due to the blending of fibrous fillers. Although it is as effective as a dog, it has the disadvantage of being expensive.

In view of this situation, the present inventor has completed the present invention as a result of intensive studies aimed at providing a styrene resin-inorganic filler composition that is low cost and has a high modification effect. .

That is, the gist of the present invention is to subject an aqueous slurry of gypsum trihydrate to pressure and heat treatment in the presence of a crystallizing agent, and then to
α-type acicular anhydrous gypsum obtained by heating and dehydrating acicular hemihydrate gypsum at a temperature of 200 to 800°C is mixed with styrene resin 1
00 parts by weight of the gypsum-reinforced styrenic resin composition.

The composition according to the present invention will be described in detail below. The styrenic resin used in the present invention includes general purpose polystyrene, rubber-reinforced high-impact polystyrene, styrene-acrylonitrile copolymer (As resin), styrene-butadiene-acrylonitrile copolymer, etc. Polymer (ABS resin), styrene-butadiene-acrylic acid ester copolymer (MBS resin)
Examples include graft polymers in which styrene alone or two types of monomers, styrene and acrylonitrile, are grafted onto EPR or EPDM as a base rubber.

As the gypsum used in the present invention, for example, an aqueous slurry of trihydrate gypsum such as phosphoric acid-side raw gypsum, flue gas desulfurized gypsum, or natural gypsum is subjected to pressure heat treatment in the presence of a crystallizing agent, and then the obtained gypsum is obtained. α-type acicular anhydrous gypsum obtained by heating and dehydrating α-type acicular hemihydrate gypsum is applied.

Preferred manufacturing conditions for such anhydrous gypsum include, for example, mixing trihydrate gypsum powder with water to prepare a slurry with a slurry concentration of 100 parts by weight, preferably 1 to 10 parts by weight, and then pH 2-6, preferably 2-3.5
After adjusting to
5 to 150℃ and pressure 1 to 8 kg/crlLG
α-type acicular hemihydrate gypsum is produced by reacting for 180 minutes.

Next, after separating this hemihydrate gypsum, 200~80%
α-type acicular anhydrous gypsum can be obtained by heating and dehydrating at a temperature of 0°C.

The modifier used when producing α-type acicular hemihydrate gypsum is usually a type of compound selected from inorganic acid salts of trivalent iron, aluminum, divalent nickel, and manganese. Used alone as an agent compound, or used in combination with one of the sodium salts of citric acid, tartaric acid, or fumaric acid and one of the sulfates of aluminum, iron, or nickel (however, the combination of sodium citrate and nickel sulfate) ) is preferred.

The amount of these crystal modifiers added (relative to trihydrate gypsum) is 0.001 to 0.0 by weight when the modifier is used alone, and 0.1 to 5.0 by weight when the modifier is used in combination. It is preferable to set the weight to 0.

It is preferable to heat and dehydrate the anhydrous gypsum from the hemihydrate gypsum rapidly, but it is necessary to be careful of cracks caused by dehydration and dislocation and accompanying crystal collapse, and to heat without damaging the acicular crystals.

The anhydrous gypsum obtained as described above is usually a high quality α-type acicular anhydrous gypsum having an average diameter to length (d/V) of 1:10 to 1:500.

The mixing ratio of the styrene resin and α-type acicular anhydrous gypsum is 100 parts by weight of the former and 5 to 100 parts by weight of the latter.

If the latter is less than 5 parts by weight, the resulting final composition will not be sufficiently modified, and if the latter exceeds 100 parts by weight,
This is not preferred because the fluidity of the final composition obtained becomes extremely poor.

To mix the above-mentioned components, the ingredients are mixed in advance using a conventional mixer, such as a tumbler, kneader, Henschel mixer, etc., and then melt-kneaded on a Banbury Mixer 1 heating roll or kneaded using an extruder. can get things.

At this time, if necessary, dyes, pigments, lubricants, plasticizers, blowing agents, and other additives may be added in types and amounts that do not have a harmful effect on the fine product of the present invention.

Since the composition of the present invention contains α-type acicular anhydrite,
The modification effect is much improved compared to the case where conventional amorphous gypsum is blended, and it is suitably used as a material for molding various industrial parts, and its industrial value is extremely high.

Next, the present invention will be explained by examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

In addition, in the following examples, physical property values were determined according to the following method.

Flexural modulus: ASTM D-790 Izot impact strength: ASTM I)-256 Heat deformation temperature: ASTM D-648 Examples 1 to 6 Composition raw materials were blended in the proportions shown in Table 2 and tumbled.
The mixture was kneaded using an extruder to form pellets.

Test pieces for measuring physical properties were prepared from the obtained pellets by injection molding, and various physical properties were measured.

The measurement results are shown in Table 2. In addition, α used in each example
An example of manufacturing acicular anhydrous gypsum is shown below.

Production example of α-type acicular anhydrous gypsum Mix phosphorus-spread gypsum and water to prepare a slurry.
Under the conditions shown in Table 1, pressure and heat treatment was performed in a pressure container.

After separating α-type acicular hemihydrate gypsum, it was dried with hot air at 90°C, and then fired at 600°C for 2 hours to obtain α-type acicular anhydrous gypsum.

This anhydrous gypsum has a diameter of 2~5 (, J, length of 100~
600 (lIJ).

The following is clear from Table 2.

It can be said that the composition of the present invention has superior physical properties and high modification efficiency compared to conventional resin compositions containing amorphous gypsum.

Claims (1)

[Claims] 1. A water slurry of dihydrate gypsum is subjected to pressure heat treatment in the presence of a crystallizing agent, and then the obtained α-type acicular hemihydrate gypsum is
α-type acicular anhydrous gypsum obtained by heating and dehydration at a temperature of 0 to 800°C is added in an amount of 5 to 1 part by weight per 100 parts by weight of styrene resin.
A gypsum-reinforced styrene resin composition containing 00 parts by weight.