JPS58134137A - Thermoplastic resin composition - Google Patents

Abstract

PURPOSE:A composition, prepared by incorporating a resin selected from an olefinic resin, styrene resin and vinyl chloride resin with an organic material, e.g. wood meal or natural fibers, and calcium oxide, and capable of giving products having beautiful surfaces and prevented the foaming phenomenon by the moisture. CONSTITUTION:A thermoplastic resin composition prepared by incorporating (A) a thermoplastic resin selected from an olefinic resin, styrene resin and vinyl chloride resin with (B) an organic substance capable of generating the moisture at 250 deg.C or below and (C) calcium oxide. The amounts of the components based on the components (A) and (B) are as follows: 10-70wt% component (B) and 0.1-20pts.wt., based on 100pts.wt. total amount of the components (A) and (B), component (C). The calcium oxide having <=65microns, preferably <=20microns, particle diameter is used as the component (C).

Description

DETAILED DESCRIPTION OF THE INVENTION Objects of the Invention The present invention relates to thermoplastic resin compositions. More specifically, (A) at least one thermoplastic resin selected from the group consisting of olefin resins, styrene resins, and vinyl chloride resins, (B) an organic substance that generates moisture at a temperature of 250° C. or lower, and ( C) relates to a thermoplastic resin composition comprising calcium oxide,
It is an object of the present invention to provide a composition for obtaining a molded article having a beautiful surface.

BACKGROUND OF THE INVENTION Thermoplastic resin compositions obtained by blending organic substances such as wood flour, natural organic fibers, and pulp with olefin resins, styrene resins, and vinyl chloride resins are widely known. These compositions can not only reduce the cost of the composition but also improve the physical properties (such as stiffness) of the thermoplastic resin by mixing the organic substance into the thermoplastic resin to increase the amount of the composition. The purpose is to improve. However, these commercially available organic materials contain a considerable amount of water, so water evaporates and scatters during heating and kneading, resulting in the generation of bubbles in the melt. Not only cannot stable granulation be performed, but also the appearance of the molded product is damaged and the physical properties are deteriorated, making it impossible to obtain a good molded product.

This is particularly noticeable when a thermoplastic resin and these organic substances are triblended and the resulting mixture is heated and O-molded.A silver streak phenomenon appears on the surface of the molded product, and moisture is present inside. Not only does it generate bubbles due to vaporization and scattering, but also the physical properties are significantly deteriorated. Furthermore, even if these organic substances have undergone common processes such as drying and pulverization,
Contains a considerable amount of water. Even if organic substances are removed through these steps, bubbles are generated as described above, which not only causes water to evaporate and escape during melt-kneading, but also spoils the appearance of the molded product. and physical properties deteriorate.

In view of the above, in order to prevent this bubble (foaming) phenomenon, for example, the organic substance is pre-dried. However, these organic substances have small bulk specific gravity and poor thermal conductivity. Therefore, this pre-drying not only requires a large amount of equipment but also a considerable amount of energy. Furthermore, even if pre-drying is performed, it is almost impossible to dry to a state where all moisture is completely removed. Furthermore, when performing kneading and granulation to remove this residual moisture, it is necessary to use a special melt-kneading extruder to form a vent, hot-cutting equipment is required because strand cutting is difficult, or sheet-forming is required. After taking it out, it is granulated into square pellets by sheet cutting. Even when granulated in this way, the molded product requires an operation and process to remove residual moisture from the composition, such as re-drying or using a vented molding machine. . Therefore, it is not only technically complicated, but also problematic in terms of economy and productivity when it is implemented industrially.

l Structure of the Invention In light of the above points, the present inventors have conducted various searches to obtain a composition in which the bubble (foaming) phenomenon is prevented. A composition comprising at least one thermoplastic resin selected from the group consisting of (B) an organic substance that generates moisture at a temperature of 250°C or less, and (C) calcium oxide, the thermoplastic resin and the organic substance The composition ratio of organic substance to the total amount of is 10 to 70% by weight, and the composition ratio of calcium oxide to 100 parts by weight of the total amount of thermoplastic resin and organic substance is o, i to 20%.
The inventors have discovered that the thermoplastic resin composition is a composition in which bubbles (foaming) phenomenon is prevented, and the present invention has been achieved.

Effects of the existing invention Since the composition obtained by the present invention is a composition in which bubbles (foaming) phenomenon is prevented, it exhibits the following effects (characteristics).

(1) Normal strand cutting is possible because foaming does not occur when kneading and granulating not only pre-dried organic substances but also untreated organic substances. It is possible to produce stable products such as

(2) By performing heat molding, a molded product with a beautiful surface without the generation of air bubbles can be obtained.

(3) Since it is unnecessary to pre-dry these organic substances, it is possible to produce compositions and molded products without the need for the above-mentioned equipment and with energy savings and cost reductions.

The composition obtained according to the present invention can exhibit the above-mentioned excellent effects without deteriorating its physical properties, and therefore can be used in a wide variety of fields. Typical examples include household electrical parts, automobile parts, and other industrial parts.

M Detailed description of the invention (A) Olefin resin The olefin resin used as the thermoplastic resin in the present invention includes an ethylene homopolymer, a propylene homopolymer, a copolymer of ethylene and propylene,
Copolymers of ethylene and/or propylene with other α-olefins having at most 12 carbon atoms (copolymerization ratio of α-olefins is at most 20% by weight), as well as ethylene and vinyl acetate, acrylic esters and a copolymer with a vinyl compound such as methacrylic acid ester (copolymerization ratio of the vinyl compound is at most 50 mol, preferably at most 40 mol). The molecular weight of these polyolefins is generally from 20,000 to 1,000,000, preferably from 1,200,000 to 500,000, and particularly preferably from 50,000 to 300,000. Also desirable are low-density and high-density ethylene homopolymers, propylene homopolymers, copolymers of ethylene and propylene, and copolymers of ethylene or propylene with other α-olefins.

These olefin resins are obtained by using a catalyst system (so-called Ziegler catalyst) obtained from a transition metal compound and an organoaluminum compound, and by supporting a chromium-containing compound (e.g., chromium oxide) on a carrier (e.g., silica). Catalytic systems (so-called Phillips catalysts) or radical initiators (e.g. organic peroxides)
It can be obtained by homopolymerizing or copolymerizing olefins using.

Furthermore, in the present invention, modified polyolefins obtained by graft polymerizing compounds having at least one double bond (for example, unsaturated carboxylic acids, -basic carboxylic acids, vinyl silane compounds) to these olefin resins are also used. included. - The manufacturing methods for these olefin resins and modified polyolefins are well known.

(B) Styrenic resin The styrene resin used in the present invention is a styrene homopolymer (generally, the molecular weight is 50,000 to 3
00000), 99.5 to 80 parts by weight in 0.5 to 20 parts by weight of a copolymer with another double bond-containing organic compound containing at least 10% by weight of styrene, and a rubbery material mainly composed of butadiene. Examples include graft polymers obtained by graft polymerizing styrene alone or styrene and an organic compound having a double bond.

Generally, these homopolymers, copolymers and graft polymers are subjected to bulk polymerization, solution polymerization,
It is produced by milk polymerization, suspension polymerization, or copolymerization of these.

Representative examples of the organic compounds having double bonds include ethylene, vinyl acetate, maleic anhydride, acrylonitrile and methyl methacrylate. Methods for producing these styrenic polymers are widely known and are used in many fields.

(C) Vinyl chloride resin Furthermore, the vinyl chloride resin used in the present invention contains a vinyl chloride homopolymer and vinyl chloride at most 5
This vinyl chloride resin is a copolymer of 0% by weight (preferably 45% by weight or less) of vinyl chloride and a compound having at least one copolymerizable double bond. and particularly preferably 400 to 1590. It has at least one double bond. Representative examples of compounds include vinylidene chloride, ethylene, propylene, vinyl acetate, acrylic and methacrylic acids and their esters, maleic acid and their esters, and acrylonitrile. These vinyl chloride resins are obtained by homopolymerizing or copolymerizing vinyl chloride alone or vinyl chloride and the above-mentioned vinyl compound in the presence of a free radical catalyst, and the manufacturing method is widely known and many methods are available. It is used in many areas.

(DJ Organic Substance) The organic substance used in the present invention is a substance that generates moisture at a temperature of 250°C or lower.

Typical examples of this organic material include wood flour, jute, rice hulls, waste paper, and pulp. Among these organic substances, from the viewpoint of mixability and moldability, those in powder form are usually preferably those with a mesh pass of 12, and those having an average particle size of 45 mesh passes or less are particularly preferred. In addition, fibrous materials generally have an average diameter in the range of 3 to 500 microns, and an average length of 0.1 microns.
~6111I+ is suitable. Note that the type of wood from which the wood powder is made is not particularly limited.

□□□) Calcium oxide Also, the calcium oxide used in the present invention includes those obtained by burning limestone, and those obtained by burning carbonates, nitrates, oxalic acid, and hydroxides. It is in the form of a fine powder, preferably having a particle size of 65 microns or less, particularly preferably 20 microns or less.

When calcium oxide with a particle size of 65 microns or more is used, defects occur on the surface of the molded product, making it difficult to obtain a molded product with a beautiful surface.

(F) Composition ratio (mixing ratio) In the composition of the present invention, the composition ratio of the organic substance to the total amount of the thermoplastic resin and the organic substance is 10 to 70% by weight, and 10 to 60% by weight is Preferably, especially 20
~60% by weight is preferred.

If the composition ratio of the organic substance to the total amount is 10% by weight or less, the effect of increasing the amount of the thermoplastic resin as the base resin and improving the physical properties is poor. On the other hand, if it exceeds 70% by weight, moldability and properties are poor, and even if molding is possible, defects will occur on the surface of the molded product, which is not preferable.

In addition, the composition ratio (mixing ratio) of calcium oxide to the total of 11,100 parts by weight of the thermoplastic resin and organic substance is 0.
, 1 to 20 parts by weight, preferably 02 to 20 parts by weight, and particularly preferably 0.5 to 15 parts by weight. If the composition ratio of calcium oxide to 1.0 parts by weight of the total amount of thermoplastic resin and organic substance is less than 0.1 parts by weight, the effects of the present invention cannot be fully exhibited. On the other hand, if the amount is 20 parts by weight or more, the foaming prevention effect is sufficiently observed, but the foaming prevention effect is not further improved, and the composition may become strongly alkaline, which is not preferable. For these reasons, the mixing ratio of calcium oxide to 1 mole of water generated by heating an organic substance is preferably 1 to 5 moles, particularly 1.
1 to 3.0 mol is suitable.

Although the thermoplastic resin composition of the present invention can be obtained by uniformly blending the above-mentioned substances, it is possible to obtain the thermoplastic resin composition of the present invention by uniformly blending the above substances. additives such as light (ultraviolet), heat and ozone stabilizers, flame retardants, lubricants, processability improvers, plasticizers, antistatic agents, colorants and electrical property improvers. A composition containing these components is also included in the thermoplastic resin composition of the present invention.

The compositions of the present invention may also be triblended using mixers commonly used in the thermoplastic resin industry such as Henschel mixers, Panbury Myers, Kneaders, Rows, Lumiles, and Screws. It can be obtained by melt-kneading using a mixer such as a one-piece extruder.

At this time, a homogeneous composition can be obtained by tri-blending in advance and melt-kneading the resulting composition (mixture). In this case, the mixture is generally melt-kneaded, then molded into pellets, and subjected to the molding described later.

Examples of the molding method include extrusion molding, injection molding, and press molding. Furthermore, molding methods commonly used in the field of thermoplastic resins such as stamping methods, press molding methods using extruded sheets, mackerel molding methods, etc. may also be applied.

Both the above-mentioned melt mixing and molding must be carried out at a temperature above the softening point of the respective thermoplastic resin used, but the thermoplastic resin and organic substances used may cause thermal deterioration. It goes without saying that the process must be carried out below the temperature.

As mentioned above, the composition of the present invention not only saves energy and reduces costs, but also has excellent production stability of good products, and can be molded into various shapes by the molding method described above. It can be used in many directions.

m Examples and Comparative Examples The present invention will now be explained in more detail with reference to Examples.

In the Examples and Comparative Examples, the melt flow index (hereinafter [MF
IJ) according to ASTM D-1238,
Measurements were made at a temperature of 230°C and a load of 2.16 kl. Moreover, the density was measured according to ASTM D-1505. Furthermore, the flexural modulus and flexural strength are AS
Measured according to TMD-790. Further, tensile strength and elongation at break were measured according to ASTM D-638.

Example 1 Propylene homopolymer with a density of 0.90097 an' (MFI 1.0!i/10 min) soiiz and wood flour (45 mesh pass, water content 6.5% by weight) 29
100 parts by weight of a mixture consisting of 5 parts by weight of calcium oxide (average particle size 10 microns) and 0.5 parts by weight of calcium stearate were mixed in advance for 5 minutes (tri-blend) using a Henschel mixer. The resulting mixture was transferred to a twin-screw vented extruder (diameter 3
Strad cutting was attempted by adjusting the resin temperature to 200° C. using 0 tan ), kneading, and then granulating (pelletizing) the mixture. In addition, using the obtained pellets, sheet extrusion was performed using a T die using an extruder (diameter 40 mm) (resin temperature 200 ° C.),
The condition and surface were observed. As a result,
I was able to cut the strands without any problems with or without suction (approximately 600ttm-Hg) (7). Furthermore, the surface condition of the strand was smooth. Furthermore, the sheet extrusion was normal and a beautiful product was obtained.

Comparative Example 1 Triblending, granulation, strand cutting, and sheet extrusion were carried out under exactly the same conditions as in Example 1, except that the calcium oxide used in Example 1 was not added. As a result, numerous air bubbles were generated in the strand despite vent suction. In addition, steam was violently scattered from the surface of the strand, and the strength of the strand was insufficient, resulting in strand breakage, making it impossible to perform normal cutting. When this pellet was used to extrude a sheet, silver streaks appeared on the surface and a beautiful sheet could not be obtained.

Example 2 Propylene homopolymer (MFI & 5 g/10 min) 50% by weight with a density of 0.90097 cm3 was heated with steam using a Henschel mixer to 160°C.
A mixture of 100 parts by weight of wood flour (100 mesh bath, residual moisture content 0.3% by weight) and 0.5 parts by weight of SO and 0.5 parts by weight of calcium stearate in Example 1 was mixed with 100 parts by weight of wood flour (100 mesh bath, residual water content 0.3% by weight) and 0.5 parts by weight of SO. Triblending, granulation, and granulation were performed in the same manner. As a result, as in Example 1, normal granulation was possible. Further, when this pellet was used to extrude a sheet in the same manner as in Example 1 and the surface condition was observed, the sheet surface was also uniform and beautiful.

Comparative Example 2 Triblending, granulation, strand cutting, and sheet extrusion were carried out under exactly the same conditions as in Example 2, except that the 7-hycalcium acid used in Example 2 was not added. Although it was possible to remove the strands by removing the blackness and suctioning the strands from the vent, surging occurred, which was thought to be due to the residual moisture, making it difficult to perform continuous and normal cutting. Furthermore, when sheet extrusion was performed using the obtained pellets, silver streaks were generated on the surface and a beautiful product (sheet) could not be obtained.

Example 3 Propylene-ethylene block copolymer with ethylene content of 9.1% by weight (density 0.900.9/crn
3. Mixture of MFI 30g/10min) 65% by weight and jute fiber (diameter 50-300 microns, moisture content
7.2 parts by weight) and 35 parts by weight, 10 parts by weight of calcium oxide (average particle size 10 microns) and 0.5 parts by weight of calcium stearate were triblended and mixed in the same manner as in Example 1. We practiced. As a result, pellets could be successfully produced in the same manner as in Example 1. Using this pellet, a test piece was molded using a 5-ounce injection molding machine (resin temperature
200℃). As a result, a good molded product could be obtained. The tensile strength of this test piece is 55 Q k
g/crn2, and the fracture elongation was 10 times (all measurements were taken across the Jr. K-6723). In addition, bending strength (ASTM D-7
The flexural modulus (measured according to ASTM D-79.0) was 765 kf/crn and the flexural modulus (measured according to ASTM D-79.0) was 48,500 kf/crn.

As a result, similar to the comparative example, surging occurred and it was difficult to perform normal cutting. Furthermore, when injection molding was performed using the obtained pellets in the same manner as in Example 3, silver streaks occurred and a beautiful product could not be obtained. The tensile strength of the obtained test piece was 31
The weight was 5 kg and 7 cm, and the elongation at break was 9%. In addition, the bending strength is 495 kg/an2, and the bending elastic modulus is 39,400 kf/cm''.

Example 4 - The amount of calcium oxide used in Example 3 was increased to 20
Triblending and granulation were carried out under the same conditions as in Example 3, except that the parts by weight were changed.

As a result, although it was observed that the kneading torque slightly increased, pellets could be produced as well as in Example 3. Further, when the obtained pellets were injection molded in the same manner as in Example 3, a molded product having a good surface although the fluidity was slightly inferior could be obtained.

Example 5 Mixture 10 consisting of 30 parts by weight of the propylene-ethylene block copolymer used in Example 3 and jute fibers (moisture content: 0.5 parts by weight) that were also predried.
0 parts by weight, 5 parts by weight of calcium oxide and 0.5 parts by weight.
Parts by weight of calcium stearate were triblended and granulated in the same manner as in Example 3. As a result, the kneading torque increased and the strands had low viscosity and were somewhat difficult to take off, but no bubbles' (foaming) phenomenon occurred. The obtained pellets were melted using an extruder in the same manner as in Example 3 and stamped to form a molded product (a box-shaped mold with a length of 15 crn, a width of 15 cm, a depth of 5 crn, and a wall thickness of 3 m). was produced, and the molded product had a good surface.

Comparative Example 4 Driving was carried out under the same conditions as in Example 5, except that a mixture in which the propylene-ethylene block copolymer used in Example 5 was 20% by weight and the jute fiber was 80% by weight was used. Blend and granulation were performed. As a result, the melt had no viscosity and could not be taken out in the form of a strand or even a sheet. For these reasons, industrial utilization of this composition is considered to be extremely difficult.

Example 6 Wood with 50% by weight of high-density polyethylene (density 0.94897Cm) with a melt index (measured according to JIS K6758 at a temperature of 190°C and a load of 2.16kl) of 1111/10 minutes (density 0.94897Cm) and 100 mesh pass 100 parts by weight of a mixture consisting of powder (moisture content 5.3% by weight) and 50% by weight, 10 parts by weight of calcium oxide (average particle size 5 microns) and 0.5 parts by weight of calcium stearate were tried in the same manner as in Example 1. Blending and granulation were performed. The obtained pellets have a diameter of 4011 mm.
A sheet was extruded using a T-die using an extrusion bonding machine No. 1111 (resin temperature: 180° C.), and the extrusion state and the surface of the obtained sheet were observed. As a result, strands with a beautiful surface were obtained regardless of the presence or absence of vent suction (approximately 600 ttan-H, g) during granulation, and the strands could be cut without any problems. Further, sheet extrusion was also normal, and a sheet with a beautiful surface was obtained.

Comparative Example 5 A triblend was prepared under exactly the same conditions as in Example 6, except that the calcium oxide used in Example 6 was not added.
Granulation and sheet molding were performed.

As a result, a large number of bubbles were generated in the strand despite the vent suction, and due to the lack of strength, normal cutting could not be performed. Further, this pellet was extruded into a sheet. However, a silver streak occurred and I was unable to obtain anything beautiful.

Example 7 Instead of the high density polyethylene used in Example 6, melt O flow index (JIS, Ni-6) was used.
According to 870, the temperature is 190℃ and the load is 10k.
Triblending, granulation, and sheet extrusion were carried out in the same manner as in Example 6, except that a styrene homopolymer having a styrene homopolymer having a styrene homopolymer having a styrene homopolymer (measured under the conditions of g) of 10 and li' of 710 minutes was used. As a result, as in Example 6, it was possible to not only granulate without any problems, but also to have a beautiful surface when inserting the sheet.

Comparative Example 6 Triblend, granulation, and sheet molding were performed under the same conditions as in Example 7, except that the calcium oxide used in Example 7 was not added.

However, similar to Comparative Example 6, Syaland foamed and normal cutting could not be performed.

Also, silver streaks occur when seedlings are seeded on sheets. However, I was unable to obtain a nail with a beautiful surface.

Example 8 70 weight of vinyl chloride homopolymer with a degree of polymerization of 1,100 (contains 30 parts by weight of di-octyl phthalate as a plasticizer and 5 parts by weight of a tin-based compound as a stabilizer based on 100 parts by weight of the polymer) Wood flour 3 used in Example 6
Tri-blending was performed in the same manner as in Example 1 using 100 parts by weight of a mixture consisting of 0% by weight and 10 parts by weight of calcium oxide (average particle size: 5 microns). The resulting mixture was kneaded and granulated (pelletized) using a non-vent type extruder (diameter 40, using a full-flight type screw) at 190"C. 40 ttm) was used to extrude the sheet using a T-die, and the extrusion state and the surface of the obtained sheet were observed.As a result, granulation could be carried out smoothly without any blisters due to foaming. .Furthermore, sheet extrusion did not cause any problems and a product with a very good surface could be obtained.

Comparative Example 7 Triblending, granulation, and sheet extrusion were carried out in the same manner as in Example 8, except that the calcium oxide used in Example 8 was not added. As a result, not only did the moisture in the composition cause severe foaming, but the surface of the strand became rough and extremely brittle, making it impossible to cut it properly. Furthermore, the pellets obtained in such a state had moisture attached to their surfaces, and could not be directly extruded into sheets.

Patent applicant: Showa Denko Co., Ltd. Agent: Patent attorney Sei Kikuchi

Claims (1)

[Scope of Claims] (A) at least one thermoplastic resin selected from the group consisting of olefin resins, styrene resins, and vinyl chloride resins; (B) an organic substance that generates moisture at a temperature of 250°C or lower and (Q) A composition consisting of calcium oxide, and the composition ratio of the organic substance to the total amount of the thermoplastic resin and the organic substance is 10 to 70% by weight.
A thermoplastic resin composition in which the composition ratio of calcium oxide is 0.1 to 20 parts by weight based on 100 parts by weight of the total amount of the thermoplastic resin and organic substance.