JPS58171426A - Polyolefin composition - Google Patents

Abstract

PURPOSE:A lightweight polyolefin composition having improved electrical conductivity, mechanical characteristics, heat resistance, etc., containing specific amounts of polyolefin modified with an unsaturated carboxylic acid or its derivative and scaly graphite. CONSTITUTION:Polyolefin (e.g., ethylene polymer, etc.) modified with an unsaturated carboxylic acid or its derivative (e.g., maleic acid, etc.) or the modified polyolefin and polyolefin (the content of the unsaturated carboxylic acid and/ or its derivative is 0.01-1.0wt%) is blended with 5-70wt% scaly graphite, and, if necessary, a stabilizer, an inhibitor for metal deterioration, a filler, etc., to give the desired polyolefin composition. EFFECT:Scarcely causing release of graphite.

Description

DETAILED DESCRIPTION OF THE INVENTION ■Object of the Invention The present invention relates to a polyolefin composition. More specifically, it relates to (2) a polyolefin modified with an unsaturated carboxylic acid or a derivative thereof, or a polyolefin composition consisting of the modified polyolefin, a polyolefin, and (1) flaky graphite, which has good electrical conductivity. Rather, it is an object of the present invention to provide a resin composition that has excellent mechanical properties and almost no flaking of graphite.

BACKGROUND OF THE INVENTION It has long been known that thermoplastic resin compositions obtained by blending carbon black with thermoplastic resins have good electrical conductivity, and have been used in a wide variety of practical applications. has been done. However, in order to obtain a composition having practically desired electrical conductivity, it is necessary to blend a considerable amount of carbon black with the thermoplastic resin. Although the composition obtained in this way has considerably improved electrical conductivity, it not only has reduced mechanical strength such as impact resistance and rigidity, but also has insufficient heat resistance and chemical resistance. In addition, the molding processability is significantly reduced, and the number of molded products is limited. Furthermore, some of the blended carbon black is liberated and peels off on the surface of the molded product, and even if the electrical conductivity is relatively good at the time of blending, the electrical conductivity decreases over time. A satisfactory molded product cannot be obtained.

Furthermore, since the surface hardness is low and the abrasion resistance is not sufficient, the composition may not be completely satisfactory when used, for example, in IC boxes, IC masks, gazettes, etc.

In addition, mechanical strength, wear characteristics, and friction characteristics are required for gears, gears, Luschig rings, packings, various casings, rollers, cams, container boxes, boxes, etc. used in the field of machinery and structural parts. There is also a demand for good heat resistance and chemical resistance.

For this gear, a composition consisting of rubber or engineering plastic mixed with a large amount of carbon black is generally used. However, the physical properties of machines and structural material articles molded using the composition are not necessarily at a level that is practically satisfactory.

0 Structure of the Invention Based on the above, the present inventors have conducted various searches to obtain a resin composition that is electrically conductive, lightweight, and has excellent mechanical properties. Polyolefin modified with its derivative (hereinafter referred to as "modified polyolefin") or the modified polyolefin and polyolefin [However, the content of the unsaturated carboxylic acid or its derivative in the circular is 0.01
A polyolefin composition which is a composition consisting of ~101 to 10% by weight and 0 flaky graphite, and in which the proportion of flaky graphite in the composition is 5 to 70% by weight, has good electrical conductivity. The present invention has been achieved based on the discovery that the filler not only has excellent properties, but also has various other excellent properties, and there is almost no peeling of the filler.

(2) Effects of the Invention The composition obtained by the present invention does not only have excellent electrical conductivity, but also exhibits the following effect (Characteristic C).

(1) It is lighter than a composition made of engineering plastic or rubber mixed with carbon black.

(2) For compositions containing carbon black,
Good heat resistance and chemical resistance.

(3) Mechanical properties such as rigidity are superior to thermoplastic resin compositions containing carbon black.

(4) Excellent molded products can be obtained without surface peeling of graphite.

The composition obtained by the present invention has the above-mentioned excellent effects (characteristics) and can be used in a wide variety of fields. Typical uses are shown below.

(1) Container box for electronic parts (2+ gears, gears, Ratschigling packing,
Parts M for machines and structural materials such as various kercings, rollers, and cams Detailed Description of the Invention 8 Modified Polyolefin The modified polyolefin used in the present invention is obtained by modifying the polyolefin described below using an unsaturated carboxylic acid or a derivative thereof. obtained by

Representative examples of unsaturated carboxylic acids or their derivatives include:
Monobasic carboxylic acids (e.g., acrylic acid, methacrylic acid) having at most 10 carbon atoms and at least one double bond; and monobasic carboxylic acids having at most 15 carbon atoms and at least one double bond. dibasic carboxylic acids (e.g., maleic acid) and anhydrides of the dibasic carboxylic acids (e.g., maleic anhydride, hymic anhydride. Among these unsaturated carboxylic acids or derivatives thereof, and 9 Particularly preferred are maleic acid and maleic anhydride.

Modified polyolefins are generally obtained by treating polyolefins with unsaturated carboxylic acids and/or derivatives thereof in the presence of organic peroxides.

In order to produce the modified polyolefin of the present invention, any of various known production methods (eg, solution method, suspension method, melt method) can be employed.

Among these production methods, when modifying a polyolefin with an unsaturated carboxylic acid or its derivative by a solution method, the polyolefin and the unsaturated carboxylic acid and/or its derivative are added to a nonpolar organic solvent, and radicals are added to ρ. A modified polyolefin can be obtained by adding an initiator and applying RF at high temperature. Inorganic organic solvents used in this case include hexane, heptane, benzene, toluene, xylene, chlorobenzene and tetrachloroethane. In addition, as a radical initiator, 2,5-dimethyl-2,5-di, (tertiary butylperoxy) total xane, 2,5-dimethyl-2,
Organic peroxides such as 5-di(tert-butylperoxy)hexyne-3 and benzoyl peroxide may be mentioned. Further, the treatment temperature is a temperature at which the polyolefin used is dissolved, and is generally 110 to 160°C, preferably 130 to 150°C.

In addition, when modifying a polyolefin with an unsaturated carboxylic acid or its derivative by a suspension method, the polyolefin and the unsaturated carboxylic acid and/or its derivative are added to a polar solvent (generally water), and then the radical initiation described above is added. It is obtained by adding an agent and processing under high pressure at a temperature of 100° C. or more.

Furthermore, when modifying a polyolefin with an unsaturated carboxylic acid or its derivative by a melting method, a melt kneading machine used in the field of general synthetic resins (for example,
It can be obtained by melt-kneading a polyolefin, an unsaturated carboxylic acid and/or its derivative, and the radical generator described above using an extruder. The kneading temperature at this time varies depending on the type of polyolefin and radical generator used, but is in the temperature range from above the melting point of the polyolefin used to below 300°C. In the case of polyethylene, generally 1
The temperature range is 20 to 270°C, and in the case of polypropylene, it is generally 160 to 270°C.

Even when using only modified polyolefin (when no polyolefin is used) or when using modified polyolefin and polyolefin together, the amount of unsaturated carboxylic acid and/or its derivative contained therein is generally 0.01 to 0.01. 1.0% by weight, especially 0.02 to 1.0% by weight.
0% by weight is preferred.

■ Polyolefin The polyolefin used in the production of the modified polyolefin or in combination with the modified polyolefin has a density of 0.9
00 to 0.980 ethylene homopolymer or random or block copolymer of ethylene and α-olefin having 3 to 12 carbon atoms (copolymerization ratio is at most 20% by weight), and propylene homopolymer or propylene and ethylene or α-olefin having 4 to 7 carbon atoms (
A random or block copolymer with a copolymerization ratio of at most 20% by weight). In carrying out the present invention, these polyolefins may be used alone or in combination of two or more. The molecular weight of the polyolefin is usually 20,000 to 1,000,000, preferably 20,000 to 500,000, and preferably 30,000 to 400,000.

These polyolefins include catalyst systems obtained from transition metal compounds and organoaluminum compounds (so-called Ziegler catalysts), and catalyst systems obtained by supporting chromium-containing compounds (for example, chromium oxide) on carriers (for example, silica). so-called Phillips catalyst)
Alternatively, it can be obtained by homopolymerizing the olefin or copolymerizing the olefin with each other or with a vinyl compound using a radical initiator (for example, an organic peroxide).

The above-mentioned modified polyolefins and their production methods are well known.

0 Scale-like graphite Also, the scale-like graphite used in the present invention is generally naturally produced and has a black or lead-black color. This density is generally 2-2! i'/crA, and its average particle size is about 02 to 50 microns. In particular, those having a diameter of 0.5 to 20 microns are preferred in the present invention.

Moreover, the aspect ratio (diameter/thickness) is 3 to 50! Something is desirable. Furthermore, this graphite is usually 65-97%
of fixed carbon.

D Composition t'1 (blending ratio) The composition ratio of flaky graphite in the composition obtained by the present invention is 5 to 70% by weight, preferably 10 to 60% by weight, particularly 20 to 60% by weight. suitable (that is, the composition ratio of the modified polyolefin or the modified polyolefin and the polyolefin is 95 to 30% by weight,
(preferably 90-40% by weight, preferably 80-40% by weight). If the proportion of flaky graphite in the composition is less than 5% by weight, a composition with good electrical conductivity cannot be obtained. On the other hand, if it exceeds 70% by weight, the molding processability is significantly reduced, making it impossible to obtain a satisfactory molded product.

[F] Composition production, molding method, etc. In producing the composition of the present invention, stabilizers against oxygen and heat, metal deterioration inhibitors, fillers, lubricants, and flame retardants commonly used in the field of polyolefins are used. Additional agents may be added.

The composition of the present invention may also be triblended using a mixer such as a Henschel mixer commonly used in the polyolefin industry, a Banbury mixer, a kneader, a roll mill, and a screw extruder. It can be obtained by melt-kneading using a machine. 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 and then molded into a pellet-like material, which is then subjected to the molding described later.

Additionally, all composition components may be mixed simultaneously when manufacturing the present invention. Alternatively, a masterbatch may be prepared by mixing some of them in advance, and the remaining composition components may be mixed into the resulting composition (masterbatch). In short, in order to produce the composition of the present invention, the purpose can be achieved by adjusting all the components to have the above-mentioned composition ratios and uniformity.

Both the melt kneading described above and the molding described below must be carried out at a temperature equal to or higher than the softening point of the modified polyolefin and polyolefin used.
If carried out at a temperature of 0°C or higher, the modified polyolefin and a part of the polyolefin may undergo thermal deterioration, so it is a matter of course that the process must be carried out at a temperature below this temperature.

In addition, in producing this composition, the modified polyolefin, polyolefin, and flaky graphite that are the composition components, as well as the polyolefin, unsaturated carboxylic acid and/or its derivative, and organic peroxide used to produce the modified polyolefin, are each Only one type may be used, or two or more types may be used in combination.

The composition of the present invention can be molded into various shapes by molding methods commonly used in the polyolefin industry such as blow molding, extrusion molding, press molding, and injection molding. Examples of shaped objects include rod-like objects, pipe-like objects, sheet-like objects, film-like objects, box-like objects, and complex-shaped objects such as gears.

EXAMPLES] EXAMPLES AND COMPARATIVE EXAMPLES The present invention will now be explained in more detail with reference to Examples.

In addition, in the examples and comparative examples, the melt flow
The index (hereinafter referred to as "MFI") is JIS K.
-6758 at a temperature of 230°C and a load of 2
．． It was measured under the condition of 1.6 Kv. Also, the tensile strength is A
Measurements were made according to STM D-638, and flexural modulus was measured according to ASTM D-790. Furthermore, the density was measured according to JIS K6758. Moreover, heat resistance was measured according to ASTM I)-648. Furthermore, the surface resistivity is ASTM D-
257. Furthermore, surface peeling was evaluated by completely adhering commercially available cellophane tape to a flat plate obtained by injection molding, and then rapidly peeling off the cellophane tape.

Example 1 Modified polyolefin with density of 0.900 g/cri
propylene homopolymer (MFI O, 9II/10
min.) ioo parts by weight, 0.01 parts by weight of 2.5-dimethyl-2, S-si(butylperoxy)hexane (as organic peroxide), and maleic anhydride were prepared in advance using a Henschel mixer. A minute tri-blend was performed. The resulting mixture was melt-kneaded using an extruder to form modified polypropylene [hereinafter referred to as "modified P P (1) J
was manufactured. The content of maleic anhydride in the modified PP (1) was 0.75%T by weight.

5 parts by weight of this modified PP (1), 60 parts by weight of a propylene homopolymer with an MFI of 20 g/10 minutes, and 35 parts by weight of flaky graphite (average particle size 10 microns, spectral ratio 7).
20) was mixed for 5 minutes using a Henschel mixer (tri-blend). The resulting mixture was melt-kneaded (resin temperature: 210°C) using a single-screw extruder to form pellets. The obtained pellets were injection molded using an injection molding machine (resin temperature: 210°C) to produce samples for measuring physical properties.

Example 2 A modified polypropylene [modified PP (referred to as 211) having a maleic anhydride content of 0.855% by weight or less] was produced in the same manner as in Example 1.

50 parts by weight of the propylene homopolymer used in Example 1, 10 parts by weight of modified PP (2+) and 40 parts by weight of flaky graphite used in Example 1 were triblended and melt-kneaded in the same manner as in Example 1. , pellets were produced.The pellets thus obtained were injection molded in the same manner as in Example 1 to produce samples for measuring physical properties.

Example 1 Example 3 Instead of the propylene homopolymer used in Example 2, 60 parts by weight of propylene-ethylene block copolymer (ethylene content 20% by weight) and 30 parts by weight of flaky graphite were used. Except for the change, tri-blending and melt-kneading 9 were performed under the same conditions as in Example 2 to produce pellets.

The obtained pellets were injection molded in the same manner as in Example 2 to produce samples for measuring physical properties.

Example 4 Modified polypropylene (maleic anhydride content 0.6% by weight) used in Example 2 instead of modified PP (2+)
, MFI 2 og/io min) and 40 parts by weight of the flaky graphite used in Example 2 were triblended and melt-kneaded in the same manner as in Example 2 to produce pellets. This pellet was injection molded in the same manner as in Example 2 to produce a sample for measuring physical properties.

Comparative example I MFI is 20. Tri-blending and melt-kneading were performed in the same manner as in Example 1 to produce pellets using 65 parts by weight of polypropylene and 35 parts by weight of the flaky graphite used in Example 1. was injection molded in the same manner as in Example 1 to produce samples for measuring physical properties.

Comparative Example 2 65 parts by weight of the modified polypropylene used in Example 4 and acetylene black (average particle size 42 millimicrons, surface area 70n?/g, apparent specific gravity 0.032)3
5 parts by weight were triblended and melt-kneaded under the same conditions as in Example 4 to produce pellets. The pellets thus obtained were injection molded in the same manner as in Example 4 to produce samples for measuring physical properties.

The density of each sample obtained as above,
Measurements of MFI, tensile strength, heat resistance (HDT), flexural modulus and surface resistivity as well as cellophane tape surface peeling tests were carried out. The results are shown in Table 1.

In addition, in the column of "Cellotape surface peeling" in Table 1,
◎ shows no adhesion of graphite to the cellophane tape due to peeling. ○ shows adhesion due to peeling and ■ formation. × indicates a considerable amount of adhesion.

From the results of the above Examples and Comparative Examples, the composition obtained by the present invention has no added surface peeling and has excellent mechanical properties, heat resistance, and surface resistivity. Patent applicant Showa Denko K.K. agent Patent attorney Sei Kikuchi-RQ-

Claims (1)

[Scope of Claims] A polyolefin modified with an unsaturated carboxylic acid or a derivative thereof, or the modified polyolefin and a polyolefin [provided that the content of the unsaturated carboxylic acid and/or its derivative in Q is 0.01 ~1.0% by weight] and 9. A polyolefin composition comprising scaly graphite in which the proportion of scaly graphite in the composition is 5 to 70% by weight.