JPS61168650A - Rigid vinyl chloride resin composition - Google Patents

Abstract

PURPOSE:To provide the title compsn. which has excellent appearance and mechanical strength and little causes heat deformation and heat shrinkage, consisting of a graft polymer obtd. by polymerizing vinyl chloride and an alkyl acrylate/ethylene copolymer and electrically carbon black. CONSTITUTION:A 99-60wt% monomer mixture of 80-100wt% vinyl chloride and 20-0wt% copolymerizable monomer (e.g. vinyl acetate) is polymerized in the presence of 1-40wt% copolymer composed of 5-75wt% alkyl acrylate and 95-25wt% ethylene to obtain a graft copolymer (A) having a specific viscosity of 0.14-0.31. 15-40pts.wt. electrically conductive carbon black having oil absorption of 300-400ml/100g and a surface area of 800m<2>/g or above, not more than 5pts.wt. lubricant and not more than 10pts.wt. stabilizer are blended with 100pts.wt. component A.

Description

Detailed Description of the Invention (1) Industrial Application Field The present invention relates to a vinyl chloride resin composition comprising a specific vinyl chloride graft polymer mixed with conductive carbon black. The present invention relates to a rigid vinyl chloride resin composition that provides molded products with excellent mechanical strength, low heat deformability and heat shrinkage, and is highly conductive and has excellent processability and component dispersibility.

Conventionally, conductivity has been achieved by blending conductive substances such as conductive carbon or fine metal powder with thermoplastic polymers such as vinyl chloride polymers, polyolefins, polystyrene, and ethylene-vinyl acetate copolymers, and then heat-molding them. It is already widely practiced industrially to obtain molded products. This conductive molded product can be used, for example, as a corona discharge prevention material for high-voltage power transmission lines, or as an antistatic packaging material for IC products.

It is widely used as electrical dust collector covers, antistatic sheets, antistatic flooring materials, surface heating elements for floor heating, other electrical parts, precision equipment, etc. Among the thermoplastic polymers used in these industrial applications, vinyl chloride polymers have come to occupy an important position due to their easy processability, variety of processing methods, good physical properties, and relatively low cost. However, in soft formulations using vinyl chloride homopolymer or vinyl chloride/vinyl acetate copolymer, a large amount of plasticizer is used, so there is The heat generated by friction during cross-contact wires is alleviated and can be ignored, and the fluidity is good and there are no processing problems (and there are almost no problems with product properties such as strength. Also, in the hard field Conventionally, the conductivity required for antistatic purposes is considered to be sufficient with a volume resistivity of about 10'Ω, and therefore, only a small amount of carbon black is required, so vinyl chloride polymers are used. There were no particular problems in processability or physical properties after molding.

(2) Conventional technology and its problems However, in recent years, there has been an increasing demand for hard molded products with higher conductivity, less microscopic conductive unevenness, and less thermal deformation, mainly in the video disc field.

To reduce the amount of thermal deformation.

By making the dispersion of the conductive substance as uniform as possible and making the melt viscosity as low as possible during molding, it is possible to avoid molding distortion, and at the same time, the heat deformation resistance (T, 9) may be increased to make it difficult for the residual strain in the molded body to relax.

However, generally, vinyl chloride resins with low melt viscosity have poor mechanical strength and low heat deformation temperature, and when a large amount of carbon black is added, thermal stability during processing becomes poor. Therefore, it is extremely difficult to simultaneously satisfy fluidity, strength, heat deformation resistance, and thermal stability.

Therefore, it has been proposed to use a graft polymer obtained by graft polymerizing vinyl chloride to a copolymer of ethylene and vinyl acetate as a resin (Japanese Patent Application Laid-Open No. 1030-1982).
. However, although the composition of this proposal has generally satisfactory fluidity and strength, it cannot be said that the heat deformation resistance and thermal stability are necessarily sufficient.

(3) Means for solving the problem Therefore, the present inventor conducted repeated studies to develop a composition with a good balance of fluidity, strength, heat deformation resistance, and thermal stability, and as a result, the present invention was developed. It was completed.

That is, the present invention provides copolymers 1 to 75% by weight of alkyl acrylate and 95 to 25% by weight of ethylene.
100 weight % of a graft polymer obtained by polymerizing 99 to 60 weight % of vinyl chloride to 40 weight % of vinyl chloride or 99 to 60 weight % of a monomer mixture of 80 weight % or more of vinyl chloride and 20 weight % or less of a monomer copolymerizable therewith. The present invention provides a rigid vinyl chloride resin composition containing 40 parts by weight or less of conductive carbon black per part.

The alkyl acrylate in the copolymer of alkyl acrylate and ethylene that constitutes the graft polymer used in the present invention includes lower alkyl acrylates such as methyl, ethyl, propyl, and butyl.
A typical example is ethyl acrylate. This content is 5 to 75% by weight in the copolymer. If it exceeds 75% by weight, the compatibility with vinyl chloride will improve, but the effect of improving impact resistance will decrease, while if it is less than 5% by weight, the effect of improving impact resistance will improve, but the compatibility with vinyl chloride will improve. Solubility decreases. The amount of the copolymer of alkyl acrylate and ethylene used is 1 to 40% by weight, preferably 2 to 20% by weight based on the total amount of the copolymer with the other component to be subjected to graft polymerization.
It is. When this amount is less than 1% by weight, the effect of improving impact resistance is reduced, and when it exceeds 40% by weight, heat shrinkability and molding surface deteriorate.

When the monomer component graft-polymerized to the alkyl acrylate-ethylene copolymer in the graft polymer contains a monomer other than vinyl chloride.

Its proportion is generally 30% by weight in the mixture with vinyl chloride.
It is as follows. Monomers copolymerizable with vinyl chloride include olefins such as ethylene and propylene, vinyl esters of fatty acids such as vinyl acetate, acrylic acid, methacrylic acid, and maleic acid.

Unsaturated acids such as fumaric acid, unsaturated acid esters such as methyl acrylate, unsaturated acid anhydrides and their esters such as maleic anhydride, nitrile compounds such as acrylonitrile, alkyl vinyl ethers such as methyl vinyl ether and cetyl vinyl ether, and dichlorides. Examples include vinylidene compounds such as vinylidene.

Specific viscosity of the graft copolymer used in the present invention (
JISK-6721) is 0.14 to 0.31.

It is preferable that there be. If a graft polymer with a specific viscosity of less than 0.14 is used to form a molded product, the strength will be poor and this is not preferable.On the other hand, if a graft polymer with a specific viscosity of more than 0.31 is used, the melt viscosity will be high and moldability will be poor. In addition to this, the dispersion of carbon black becomes non-uniform, which is not preferable.

The conductive carbon black used in the present invention has an oil absorption (JISK-6221) of 300 to 400 d.
/100,9 and surface area (AsTMD3o37-37
) 800 m:/, preferably 9 or more. Oil absorption amount 30
If carbon black with a surface area of less than 0d/100.9 or a surface area of less than 5oorllI is used, it is not possible to obtain a molded product with a low specific resistance per volume, and the oil absorption amount is 400it//
If it exceeds 100.9, the melt viscosity is high (it generates a lot of heat and processing is difficult, and the carbon black tends to become non-uniform, which is undesirable.) From the viewpoint of processability and strength of the molded product, the carbon black used should be as small as possible and have a high Carbon black is preferable to give conductivity.

It is used in an amount of 40 parts by weight or less per 100 parts by weight of the graft polymer. The lower limit is determined according to the required value of volume resistivity.For example, in order to make it 50Ωα or less,
5 parts by weight or more is required. If it exceeds 40 parts by weight, the melt viscosity is high and heat generation during processing is large (not only is this a problem in processing, but the physical properties of the obtained molded product are also poor, which is not preferable).

The composition of the present invention may contain a vinyl chloride polymer compounding agent, if desired. In the case of a lubricant and a plasticizer, each can be used in an amount of 5 parts by weight or less per 100 parts by weight of the graft polymer.

If the lubricant exceeds 5 parts by weight, it is not preferable because it causes non-uniform dispersion of carbon black in the molded product.

Moreover, if the plasticizer exceeds 5 parts by weight, the softening temperature of the molded product will become low, which is not preferable. The stabilizer can be used in an amount of 10 parts by weight or less, and the silicone-based, fluorine-based, etc. lubricant can be used in an amount of 5 parts by weight or less.

Carbon black and various additives may be blended into the graft polymer during processing using a normal glue pump blender, Banbury mixer, high-speed stirrer, etc., or may be charged together with the monomer in the polymerization machine during the production of the graft polymer. Furthermore, it may be added and mixed into the slurry of the graft polymer before drying.

The composition of the present invention has extremely good fluidity.

The molded product has a low volume resistivity and a high softening temperature, so it is particularly useful for video discs, audio discs, computer discs, etc.

(4) Examples Below, a few examples will be given and explained. Note that the proportions and numbers of monomers and additives used are based on weight. Also, 4f! The sample preparation method and testing method for the example materials are as follows.

"Sample preparation method"...Add the polymer, carbon black, stabilizer, and Isohan Rubber Lubricant 4 Tokuuki to a high-speed stirrer, stir thoroughly, and set the resulting powder composition at 170°C. A portion of the pellets was extruded using an extruder equipped with a 5-m square pellet, and the pellets were used as test samples for flow rate, dynamic thermal stability, and orin bending strength. Furthermore, some of them were extruded into rod shapes with diameters of 4W and 2 (1 m), and used as samples for heating shrinkage rate, molded product surface skin observation, and volume resistivity measurement.
A press plate was obtained by pressing for 5 minutes at a pressure of 1 aokg/d in a press molding rock set at 75°C. This press plate was used to evaluate the flexibility temperature and carbon black dispersibility.

"Outflow amount"...10m using a high-speed flow tester
Using a nozzle of X1nφ, a 5m square pellet sample was heated to a temperature of i
Value when extruded under the conditions of soC and load zsokg/cd (based on JISK-7210 flow test method (reference test)). The larger this value is, the better the workability is.

"Dynamic thermal stability"---Pravender Plastograph with chamber capacity 60cc and spindle rotation speed 6Orp
m.

Rotor rotation ratio 2:3. A 5111 square beret sample of 68.9 was charged under the condition of a chamber temperature of 170°C, and rotated after preheating for 3 minutes. From this point on, the torque began to increase. ) ° It is indicated by the time it takes for the test paper to become colored due to the decomposition of hydrochloric acid gas. This time is 15
Materials with a thickness of less than 100 mm are undesirable because they may decompose depending on the molding conditions.

"Heating shrinkage rate"... A 20 wφ rod-shaped extrudate is cut to the proverbial length of 10 mm to make a tablet. Place the same tablet in the center of a 40 shoulder φ x 2 m mold at 150°C.
The mixture was pressed for 3 minutes, cooled, and then taken out to obtain a disc having a diameter of 40 m x 2. Eight gauge points are placed on this disk at equal intervals along the circumference, and the distance between the center point and the gauge points is J1~a.
Each of these is enlarged using a shadow graph and measured accurately. After heating the same sample at 70°C for 2 hours,
Each gauge distance IIJ, ~S was measured again at ℃, and the rate of change before and after heating was calculated using the following formula, and the arithmetic average of the rates of change of the eight gauge distances was taken as the heating shrinkage rate.

No. "Soft Temperature"...JIS K-674
The measurement was carried out by the method of measuring the flexibility temperature of a hard vinyl chloride resin plate according to No. 5. A material having a softness temperature of less than 55° C. is undesirable because it causes deformation due to a slight temperature change after molding.

"Carbon black dispersibility"...from the press plate.

A section with a thickness of 1 μm was prepared using a microtome, and a photograph was taken at 200x magnification using an optical microscope transmission method. The size and number of carbon black aggregates present in an area of 9200 x 300 μm were ranked from A to C below. It represents the state of dispersion.

A (excellent dispersion): 20 or less aggregates with a maximum width of 5 μm or more, and a grade of 4 with a maximum width of 20 μm or more.

B (Good dispersion): A state in which there are 20 or less aggregates with a maximum width of 5 to 30 μm and one or more aggregates with a maximum width of 20 μm or more.

C (poor dispersion): A state in which there are 20 or more aggregates with a maximum width of 5 μrlL or more.

"Volume resistivity": A rod-shaped extrudate with a diameter of 4wi is cut to a length of 7.51 mm, and the length is measured with a caliper, and the diameter is measured with a microphone and a rhometer. Thereafter, silver paint was applied to both ends of the sample to form electrodes. The resistance values at both ends were measured using a tester, and the volume resistivity was calculated using a linear equation.

"All-in bending strength"...A8TMD-747
Measurements were made using an All-in-Stiffness tester based on the following, under conditions of a weight of 5 in-jb and a span spacing of 1/41 nch. The sample was 1 ca x 3 c from a plate obtained by pressing a 5-angle beret sample using a 75-ton press machine.
A sample piece cut out from m X OoI C11l was used.

Materials with a measured value of less than 5 degrees are not preferred as hard molded products.

Example 0.2 of partially saponified polyvinyl acetate was placed in a polymerization can with a capacity of 0.2 torr.
parts, trichlorethylene 1 to 3 parts, cellulose derivative 0.1 parts
1 part and 0.4 part of dilauroyl peroxide were added, stirred at room temperature, and degassed. on the other hand.

After charging the ethylene copolymer, vinyl chloride monomer, and other desired monomers into a separate sealed container and completely dissolving them, the entire amount was transferred for each of the above polymerizations, and the temperature was raised to 1. The graft polymer shown in the table was obtained.

The polymer used in Comparative Example 1 was prepared in the same manner as the others except that the ethylene copolymer was not used. The obtained polymer was separated and dried by a conventional method to prepare a sample for evaluation.

The results of measuring the properties of the composition prepared according to the following formulation are shown in the table.

Blend Graft polymer (see table) xoo@dioctyltin maleate 2.5 dibutyltin dilaurate 0.5 epoxidized soybean oil
0.5 lubricant
0.5 Ketchen Black EC (manufactured by Lion Axie, oil absorption 355 d/100 y, Table 20 Area 1000 m'/#) As is clear from the table, the composition of the present invention has excellent overall properties.

Claims (1)

[Claims] Alkyl acrylate 5-75% by weight and ethylene 95-95%
25% by weight of a copolymer consisting of 1 to 40% by weight of vinyl chloride or 99 to 60% by weight of a monomer mixture of 70% by weight or more of vinyl chloride and 30% by weight or less of a monomer copolymerizable with it. A rigid vinyl chloride resin composition comprising 40 parts by weight or less of conductive carbon black per 100 parts by weight of a graft polymer obtained by polymerization.