JP2884634B2 - Method for producing thermoplastic resin composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a thermoplastic resin composition containing fibrous or acicular magnesium oxysulfate.

[Prior art] A technique of blending an inorganic substance for the purpose of improving various properties such as rigidity, mechanical properties, heat resistance, molding shrinkage, and dimensional stability of a thermoplastic resin molded product is well known. For example, particulate substances such as calcium carbonate, barium sulfate and magnesium hydroxide, small plate-like or flake-like substances such as talc and mica, and fibrous substances such as glass fibers and asbestos are used.

Among these inorganic substances, particulate substances do not have a very high effect of reinforcing the thermoplastic resin, so thermoplastic resin molded products obtained by blending the particulate substances are not suitable for industrial materials that require high performance. Not generally available. On the other hand, a plate-like or flake-like substance or a fibrous substance is widely used as a reinforcing material for a thermoplastic resin because it exhibits a high two-dimensional or one-dimensional reinforcing effect. However, these highly effective reinforcing materials have various disadvantages on the one hand, and the use of the reinforcing material may be restricted depending on the purpose. For example, a thermoplastic resin containing a small plate-like or flake-like substance generally has a lower level of rigidity of a molded product when compared with a resin containing a fibrous substance such as glass fiber, and has a flow mark during molding. There is a drawback that it is easy to occur. On the other hand, when a fibrous substance is blended, the molded product has small elongation, tends to cause silver streaks, and often has poor gloss.
In particular, when glass fiber is used, there is a drawback that the molded product is vulnerable to falling ball impact.

Therefore, when using these conventional reinforcing materials, it is necessary to take into account the drawbacks of the reinforcing materials and to select them according to the use symmetry of the molded article.

It is already known to use fibrous or acicular magnesium oxysulphate as an additive for thermoplastics and thermosetting resins. That is, a crystalline polypropylene is used as the thermoplastic resin, and a polypropylene composition having improved physical properties is described in JP-B-62-9260, and rigidity is disclosed in JP-A-59-96153. An improved vinyl chloride resin composition is described. Further, JP-A-59-86654 discloses a phenolic thermosetting molding material having excellent electrical properties and heat resistance.

Japanese Patent Publication No. 62-9260 discloses that fibrous or acicular magnesium oxysulfate causes a dehydration reaction at a high temperature to release water of crystallization, and the kneading operation with polypropylene is performed at 250 ° C. or lower, preferably 190 to 240 ° C. ℃ (resin temperature)
It is shown that it is better to carry out within the range.

[Problems to be Solved by the Invention] Fibrous or acicular magnesium oxysulfate causes a dehydration reaction at 250 ° C. or higher and releases water of crystallization. Therefore, when trying to use as a reinforcing material of a thermoplastic resin having a molding temperature of 250 ° C. or more, the obtained thermoplastic resin composition contains bubbles, and a molded product obtained by molding this thermoplastic resin composition is It has problems that it contains cavities and pinholes, and that silver streaks and flow marks are generated.

An object of the present invention is to provide a fiber or needle-shaped magnesium oxysulfate that improves various properties such as rigidity, mechanical properties and heat resistance, has no voids or pinholes, and does not generate silver streaks or flow marks. An object of the present invention is to provide a method for producing a thermoplastic resin composition capable of molding a product.

[Means for Solving the Problems] An object of the present invention is to provide one or more thermoplastic resins selected from the group consisting of ABS resin, polyamide, modified polyphenylene oxide, polycarbonate, and polymethylpentene. Parts by weight, fibrous or acicular magnesium oxysulfate 5 to 100 parts by weight, at a temperature of 250 to 340 ° C., melting and kneading while degassing for 1.5 to 10 minutes while fibrous or acicular magnesium This is achieved by a method for producing a thermoplastic resin composition containing oxysulfate.

Fibrous or acicular magnesium oxysulfate is prepared by the method described in Japanese Patent Application No. 62-282122, that is, magnesium sulfate or magnesium oxide having a BET specific surface area of 20 m ² / g or less in an aqueous solution of magnesium sulfate having a concentration of 25 m ² / g or less. 100 ~ 300 ℃
Can be suitably produced by a method of performing a hydrothermal reaction at a temperature of

Further, after the method described in Japanese Patent Application No. 63-38609, that is, magnesium sulfate and magnesium hydroxide or magnesium oxide are dispersed so as to have a concentration of 25% by weight or less, 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 a method in which a surfactant is added to the hydrothermal reaction system.
The resulting fibrous or acicular magnesium oxysulfate has an X-ray powder diffraction spectrum of ASTM No. 7-4.
15 is in good agreement with that of ASTM No. 7
-415 considered can be represented by _{MgSO 4 · 5Mg (OH) 2} · 3H 2 O is a rational formula described.

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, a diameter (fiber diameter) of 0.1 to 10 μm, and an apparent specific gravity of 0.05 to 0.3. Or needle-like substance.

The amount of fibrous or acicular magnesium oxysulfate to be added to the thermoplastic resin in order to improve the rigidity, mechanical properties, heat resistance, etc. of the thermoplastic resin is 5 to 100 parts by weight based on 100 parts by weight of the thermoplastic resin. Parts are preferred. When the amount is less than 5 parts by weight, the effect of adding the fibrous or acicular magnesium oxysulfate is small, and when the amount is more than 100 parts by weight, the viscosity becomes high and molding becomes difficult.

The thermoplastic resin used in the present invention is a thermoplastic resin having a molding temperature of 240 ° C. or higher, and specific examples include ABS resin, polyamide, polybutylene terephthalate, modified polyphenylene oxide, polyethylene terephthalate, polycarbonate, and polymethylpentene. .

Known filling and / or reinforcing materials can be added to the above-mentioned composition of the present invention. As particulate matter,
Examples include calcium carbonate, barium sulfate, and magnesium hydroxide. Examples of the plate material include talc, mica, clay (such as kaolin), glass flake, graphite, and aluminum flake. As the fibrous material, glass fiber, carbon fiber, metal fiber, organic fiber (aromatic polyamide fiber, Besides polyester fiber, etc.), asbestos, wollastonite, mineral fiber, potassium titanate fiber, gypsum fiber and the like.

Fibrous or acicular magnesium oxysulfate undergoes a two-stage dehydration reaction at elevated temperatures. According to the differential thermal analysis in the air atmosphere, the first-stage dehydration reaction was 250 ° C.
And end at 290 ° C. The second stage dehydration reaction starts at 340 ° C and ends at 400 ° C. Therefore, the melting and kneading temperature of the thermoplastic resin and the fibrous or acicular magnesium oxysulfate is preferably from 250 ° C to 340 ° C.

At a temperature lower than 250 ° C., the melting temperature (molding temperature) of the thermoplastic resin may be lower than the temperature, and the first-stage dehydration reaction is not completed. May not be able to be manufactured. At a temperature exceeding 340 ° C., a second-stage dehydration reaction occurs, and the strength of fibrous or acicular magnesium oxysulfate decreases.

Melting of thermoplastic resin and fibrous or acicular magnesium oxysulfate, kneading method, before dry blending using a known mixer such as Henschel mixer, ribbon blender, V-type blender, uniaxial or biaxial A method of melting and kneading with an extruder, a Banbury mixer, a roll, etc., and a single-screw or twin-screw extruder, a Banbury mixer, a roll, etc. without dry blending a thermoplastic resin and fibrous or acicular magnesium oxysulfate And a method of melting and kneading. Performing a degassing operation (venting) during melting and kneading further improves the effects of the present invention.

As a molding method, a known molding method such as injection molding, extrusion molding, hollow molding, compression molding, vacuum molding, thick-air molding, layered molding, roll processing, stretching processing, stamping processing and the like can be used.

[Function] Fibrous or acicular magnesium oxysulfate used to improve physical properties such as rigidity, mechanical properties, heat resistance, etc. of a thermoplastic resin causes a dehydration reaction in two stages at a high temperature to release water of crystallization. I do.

In particular, the first stage dehydration reaction, the reaction start temperature is 250 ℃
Kneading with resin for near, less than 250 ℃ when molding,
Preferably, it must be performed at 240 ° C. or lower. When melting and kneading or molding the resin at a temperature above the dehydration reaction start,
Molded articles contain cavities and pinholes, and undesirably generate silver streaks and flow marks.

However, 100 parts by weight of thermoplastic resin, 5 to 100 parts by weight of fibrous or acicular magnesium oxysulfate at a temperature of 250 to 340 ° C., melting and kneading for 1.5 to 10 minutes, the obtained thermoplastic resin composition Contains no air bubbles. When molding is performed using such a thermoplastic resin composition, a favorable thermoplastic resin molded article free from voids, pinholes, silver streaks, and flow marks can be obtained even at a molding temperature of 250 ° C. or higher.

[Examples] Hereinafter, the present invention will be described with reference to examples.

Table 1 shows various measurement results of test pieces obtained by processing the compositions of the respective formulations. In the following text, “parts” means “parts by weight”. The evaluation method is as follows.

Tensile strength ASTM D-638 Flexural strength ASTM D-790 Flexural modulus ASTM D-790 Izod impact strength ASTM D-256 Silver streak Occurrence of occurrence by visual observation of molded product Judgment by visual observation of molded product with flow mark Example 1 Nylon 6 was added to a 2-axis kneader with a nozzle set temperature of 280 ° C.
80 parts of resin, 20 parts of fibrous or acicular magnesium oxysulfate are supplied and melted and kneaded, and after removing some of the crystals of fibrous or acicular magnesium oxysulfate, the mixture is cooled, and a thermoplastic resin composition is obtained. Was manufactured. 2
The melting and kneading time of the shaft kneader was 2 minutes. Also,
A deaeration operation was performed when melting and kneading. Using the obtained thermoplastic resin composition, a nozzle setting temperature of 280 ° C. and a mold temperature of 8
Injection molding was performed at 0 ° C. to prepare test pieces for measuring various physical properties. Table 1 shows the obtained results.

Example 2 To a biaxial kneader having a nozzle setting temperature of 275 ° C., 24 parts of a graft copolymer and 56 parts of a hard copolymer, 20 parts of fibrous or acicular magnesium oxysulfate were supplied as ABS resin components and melted. After kneading, a part of the crystal of fibrous or acicular magnesium oxysulfate was removed, and the mixture was cooled to produce a thermoplastic resin composition. The melting and kneading time of the biaxial kneader was 2 minutes. In addition, a deaeration operation was performed during melting and kneading. Using the obtained thermoplastic resin composition, injection molding was performed at a nozzle set temperature of 275 ° C. and a mold temperature of 80 ° C. to prepare test pieces for measuring various physical properties. Table 1 shows the obtained results.

Reference Example 1 Nylon 6 resin with nozzle setting temperature 260 ° C, mold temperature 80
Injection molding was performed at ℃ to prepare test pieces for measuring various physical properties.
Table 1 shows the obtained results.

Reference Example 2 An ABS resin (graft copolymer / hard copolymer = 3/7) was injection molded at a nozzle setting temperature of 230 ° C. and a mold temperature of 80 ° C. to prepare test pieces for measuring various physical properties. The obtained result is
It is shown in the table.

Comparative Example 1 A thermoplastic resin composition was produced in the same manner as in Example 1 except that the melting and kneading time of the biaxial kneader were changed to 1 minute. A test piece for measuring physical properties was prepared in the same manner as in Example 1 using the obtained thermoplastic resin composition.

 Silver streaks were observed in the test pieces.

Comparative Example 2 A thermoplastic resin composition was produced in the same manner as in Example 2, except that the melting and kneading times of the biaxial kneader were changed to 1 minute. A test piece for measuring physical properties was prepared in the same manner as in Example 2 using the obtained thermoplastic resin composition.

 Silver streaks were observed in the test pieces.

Example 3 Nylon 6 was added to a 2-axis kneader with a nozzle set temperature of 280 ° C.
60 parts of resin, 40 parts of fibrous or acicular magnesium oxysulfate are supplied, melted and kneaded, a part of water of crystallization of fibrous or acicular magnesium oxysulfate is desorbed, and then cooled to obtain a thermoplastic resin composition. Was manufactured.
The melting and kneading time of the biaxial kneader was 2 minutes. In addition, a deaeration operation was performed during melting and kneading. The obtained thermoplastic resin composition (60 parts) and polypropylene (40 parts) were supplied to a biaxial kneader having a nozzle set temperature of 260 ° C., melted and kneaded, and then cooled to produce a thermoplastic resin composition. The three-component thermoplastic resin composition was injection molded at a nozzle setting temperature of 260 ° C. and a mold temperature of 80 ° C. to prepare test pieces for measuring various physical properties. Table 1 shows the obtained results.

Reference Example 3 60 parts of nylon 6 resin and 40 parts of polypropylene were supplied to a biaxial kneader having a nozzle set temperature of 260 ° C., melted and kneaded, and then cooled to produce a thermoplastic resin composition. The obtained thermoplastic resin composition was heated at a nozzle setting temperature of 260 ° C. and a mold temperature of 80.
Injection molding was performed at ℃ to prepare test pieces for measuring various physical properties.
Table 1 shows the obtained results.

Comparative Example 3 24 parts of a graft copolymer and 56 parts of a hard copolymer and 20 parts of a fibrous or acicular magnesium oxysulfate were supplied as ABS resin components to a biaxial kneader having a nozzle set temperature of 230 ° C. and melted. The mixture was kneaded to produce a thermoplastic resin composition. The melting and kneading time of the biaxial kneader was 2 minutes.
Using the obtained thermoplastic resin composition, the nozzle set temperature 27
Injection molding was performed at 5 ° C. and a mold temperature of 80 ° C. to prepare test pieces for measuring animal characteristics. Silver streaks were observed in the test pieces, and good samples could not be obtained.

[Effect of the Invention] When it is attempted to use fibrous or acicular magnesium oxysulfate as a reinforcing material for a thermoplastic resin having a molding temperature of 250 ° C. or higher, the molded article contains cavities and pinholes, and has silver streaks and flow marks. Occurred and a good molded product could not be obtained. The present invention is a method for producing a thermoplastic resin composition in which the mixing ratio of the thermoplastic resin and the fibrous or acicular magnesium oxysulfate, and the melting and kneading temperature and time are specified. When the thermoplastic resin composition is used, a molded article without voids, pinholes, silver streaks or flow marks can be obtained.

────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code FI C08L 77/00 C08L 77/00 (56) References JP-A-1-240567 (JP, A) JP-A-61-285250 (JP) JP-A-1-230670 (JP, A) JP-A-59-172533 (JP, A) JP-A-3-747 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB Name) C08L 1/00-101/14

Claims (1)

(57) [Claims] 1. 100 parts by weight of one or more thermoplastic resins selected from the group consisting of ABS resin, polyamide, modified polyphenylene oxide, polycarbonate and polymethylpentene, and fibrous or acicular magnesium oxysulfate 5 Melting and kneading while degassing 1.5 to 10 minutes at a temperature of 250 to 340 ° C. with a temperature of 250 to 340 ° C., the method for producing a thermoplastic resin composition containing fibrous or acicular magnesium oxysulfate, .