JPS643898B2 - - Google Patents

Description

[Detailed description of the invention]

[] Object of the Invention The present invention relates to a chlorinated polyethylene composition with excellent chemical resistance. More specifically, (A) the degree of chlorination obtained by chlorinating raw material polyethylene having a molecular weight of at least 150,000 is 30 to 45.
% by weight of chlorinated polyethylene, (B) at least one inorganic filler selected from the group consisting of carbon black, synthetic silicate white carbon, barium sulfate and titanium oxide, (C) lead oxide, water at least one lead-containing inorganic compound selected from the group consisting of oxides and sulfates;
(D) This relates to a chlorinated polyethylene composition comprising an organic peroxide, and the purpose is to provide a composition with excellent chemical resistance (particularly acid resistance). [] Background of the Invention For some time now, crosslinking agents, vulcanizing agents, vulcanization accelerators, and vulcanization accelerators have been used in thermoplastic resin compositions and elastomers obtained by blending lubricants, plasticizers, etc. with thermoplastic resins. Molded rubber elastomer compositions obtained by vulcanization or crosslinking by adding additives such as anti-oxidants, anti-aging agents, coloring agents, antioxidants, etc., i.e. plastic products and It is well known that rubber products are widely used in industrial sealing parts (for example, packing parts) and other industrial parts, and greatly contribute to the development of the industrial field. However, in recent industrial fields, packing parts that require chemical resistance (particularly acid resistance) have been subject to strict regulations in accordance with industry trends. Thermoplastic resin products (plastic products) used in such fields have high rigidity and therefore have drawbacks such as leakage. Furthermore, rubber products cannot always be satisfied with the most important properties such as compression set, sealing resistance, and chemical resistance. For these reasons, there is a demand for materials that have excellent properties as described above. Thermoplastic elastomers with good properties such as silicon-containing rubber (silicon rubber), epichlorohydrin-based rubber, urethane-based rubber, fluorine-containing rubber]
However, there are problems in terms of processability and cost. On the other hand, generally used thermoplastic elastomers have no problem in terms of price, but they have double bonds and therefore have poor heat resistance and weather resistance. For this purpose, anti-aging agents, antioxidants, etc. are added, but not only do the anti-aging agents and antioxidants bleed, but all of the properties have advantages and disadvantages, and cannot necessarily be said to be satisfactory. Furthermore, problems with individual thermoplastic elastomers that are commonly used will be discussed in detail. Styrene-butadiene copolymer rubber (SBR) and acrylonitrile-butadiene copolymer rubber (NBR) have excellent oil resistance, cold resistance, and bending resistance, but because they have double bonds in their structure, they are weather resistant. Even if a relatively large amount of anti-aging agents, antioxidants, etc., which have good properties and ozone resistance are added, the long-term retention is poor. Furthermore, among the most important requirements, chemical resistance, it is inferior. Furthermore, chloroprene rubber (CR) exhibits excellent oil resistance, cold resistance, and bending resistance. However, since SBR and NBR have double bonds, short-term weather resistance and ozone resistance can be improved by adding relatively large amounts of anti-aging agents. However, with long-term use, these characteristics deteriorate. Furthermore, like SBR and NBR, it has poor chemical resistance (especially acid resistance). Further, isoprene-isobutylene copolymer rubber (IIR) also has poor chemical resistance (especially acid resistance). [] Structure of the Invention Based on the above, the present inventors have developed a thermoplastic elastomer that is relatively low cost, improves the drawbacks of these commonly used thermoplastic elastomers, and has a strong acid (for example, 50% or more As a result of various searches to obtain a thermoplastic elastomer composition that can withstand nitric acid), we found that (A) the degree of chlorination obtained by chlorinating raw material polyethylene having a molecular weight of at least 150,000 is 30 to 30; 45% by weight of amorphous chlorinated polyethylene; (B) at least one inorganic filler selected from the group consisting of carbon black, synthetic white silicate carbon, barium sulfate and titanium oxide; (C) lead. (D) at least one lead-containing inorganic compound selected from the group consisting of oxides, hydroxides, and sulfates; and (D) an organic peroxide, the composition ratio being based on 100 parts by weight of the chlorinated polyethylene The inorganic filler is 20
~100 parts by weight and 25-30 parts by weight of lead-containing inorganic compounds
parts by weight, but the total amount of inorganic filler and lead-containing inorganic compound is at most 180 parts by weight, and the chlorinated polyethylene composition in which the organic peroxide is 0.01 to 20.0 parts by weight is relatively low cost. The present invention has been achieved based on the discovery that the composition has excellent chemical resistance. [] Effects of the Invention The chlorinated polyethylene composition obtained by the present invention not only can be produced at low cost, but also exhibits the following effects (characteristics). (1) Excellent weather resistance. (2) Good wear resistance. (3) Excellent flexibility. (4) Good oil resistance (aromatic oil, aromatic oil). (5) Excellent flexibility and cold resistance. (6) Good dimensional accuracy. (7) Not only does it have good molding processability, but it also has a low shrinkage rate during molding. (8) Low compression set. (9) Excellent chemical resistance (especially acidic), which is the most characteristic feature of the present invention. For example, it can withstand nitric acid concentrations of 50% or more. The chlorinated polyethylene composition obtained by the present invention not only has good chemical resistance, but also can be used in a wide variety of fields because it exhibits the excellent effects mentioned above. Typical uses are shown below. (1) Strong acids (e.g. nitric acid, sulfuric acid, hydrochloric acid, acetic acid)
(2) Packing materials and sealing materials used for printed piping in the chemical industry, etc. (3) Cans, etc. for transporting solutions containing halogens such as sodium hypochlorite. Packing material, sealing material. [] Detailed description of the invention (A) Chlorinated polyethylene The chlorinated polyethylene used in the present invention can be obtained by chlorinating polyethylene powder or particles in an aqueous suspension, or by chlorinating polyethylene dissolved in an organic solvent. (preferably by chlorination in an aqueous suspension). Generally, amorphous chlorinated polyethylene with a chlorine content of 30 to 45% by weight is used, and amorphous chlorinated polyethylene with a chlorine content of 32 to 45% by weight is particularly preferred. Said polyethylene is obtained by homopolymerizing ethylene or copolymerizing ethylene with at most 20% by weight of α-olefin (generally having at most 12 carbon atoms). Its density is generally between 0.910 and 0.970 g/cc. Moreover, its molecular weight is at least 150,000, and 180,000 to 700,000 is especially suitable. (B) Inorganic filler The inorganic filler used in the present invention is carbon black, synthetic silicate white carbon, barium sulfate, and titanium oxide. Carbon black generally has a specific surface area of 20 to 1800 m 2 /g measured by low-temperature nitrogen adsorption method and BET method, and a pore volume of 20 to 1800 m ² /g and a pore volume of
It is 1.5 to 4.0 cc/g measured by mercury intrusion method in the range of 30 to 7500 Å, and in particular, the specific surface area is 600 Å.
~1200 m ² /g are advantageous. Examples of the carbon black include channel black, thermal black, acetylene black, and carbon black produced by the furnace black method. Regarding these carbon blacks, please refer to "Carbon Black Handbook" (edited by Carbon Black Association, published by Tosho Publishing Co., Ltd. in 1972) and "Handbook of Rubber/Plastic Compounded Chemicals" (edited by Rubber Digest Co., Ltd., published in 1971), edited by Rubber Digest Co., Ltd. Their manufacturing methods and physical properties are well known, as described in the above-mentioned "Synthetic Rubber Handbook" published by J.D. Furthermore, as the synthetic silicate white carbon, those having an average particle size of 18 millimicrons to 0.5 microns are generally preferred. Furthermore, it is desirable that the specific surface area is 30 to 100 m ² /g,
Particularly suitable is one having an area of 30 to 80 cm ² /g. Further, the density is usually 2.0 to 2.5 g/cm ³ . Among the synthetic silicic acid white carbons, calcium salts of silicic acid (including those containing water of crystallization) are preferably used. Furthermore, barium sulfate generally includes barite powder obtained by crushing naturally produced barite and sedimentary barium sulfate, and those with an average particle size of 0.2 to 5 microns are preferred, and those with an average particle size of 0.5 to 3 microns are particularly preferred. is suitable. Also, the density is generally 4.3
~4.5g/ ^cm3 . Furthermore, titanium oxide usually has rutile and anatase forms, and those with an average particle size of 0.2 to 0.5 microns are desirable, especially 0.3 to 0.45 microns.
Micron ones are preferred. Furthermore, the density is generally between 3.9 and 4.3 g/ ^cm3 . The physical properties of these inorganic fillers are described in detail in Rubber Digest Co., Ltd., "Handbook, Rubber/Plastic Compounding Chemicals" (Rubber Digest Co., Ltd., published in 1972), pages 213 to 256 and 378. The product name etc. are listed. (C) Lead-containing inorganic compound Furthermore, the lead-containing inorganic compound used in the present invention is selected from lead oxides, hydroxides, sulfates, and double salts thereof. The lead oxide preferably has an average particle size of 0.3 to 3.0 microns, particularly preferably 0.5 to 2.0 microns. Also, the density is generally 8.3 to 9.5
g/ ^cm3 . Representative examples of this lead oxide include lead monoxide (PbO) and trilead tetraoxide (Pb ₃ O ₄ ). The lead hydroxide preferably has an average particle size of 0.5 to 5.0 microns, particularly preferably 0.9 to 2.5 microns. A typical example is lead white [2PbCO ₃ Pb(OH) ₂ ]. Furthermore, as a lead sulfate, the average particle size is 0.5~
A thickness of 5.0 microns is preferred, and a diameter of 0.5 to 2.5 microns is particularly preferred. A typical example is tribasic lead sulfate (3PbO・PbSO ₄・H ₂ O)
and basic lead sulfite (nPbO・PbSO ₃ ). Regarding these lead-containing inorganic compounds, please refer to pages 266 to 270 of the above-mentioned "Handbook, Compounded Rubber and Plastic Chemicals" and "Practical Handbook of Additives for Plastics and Rubber" edited by Kagaku Kogyosha (Kagaku Kogyosha, published in 1968). ) Physical properties etc. are described on pages 146 to 279. (D) Organic peroxide The organic peroxide used in the present invention is not particularly limited, but it is particularly desirable to have a decomposition temperature (temperature at which the half-life is 1 minute) of 120°C or higher, particularly 140°C. ℃ or higher is preferable. Representative examples of suitable organic peroxides include:
1,1-bis-tertiary-butylperoxy-
Ketone peroxides such as 3,3,5-trimethylcyclohexane, hydroperoxides such as 2,5-dimethylhexane-2;5-dihydroperoxide, 2,5-dimethyl-
Mention may be made of peroxy esters such as 2,5-di-tertiary-butylperoxyhexane, diacyl peroxides such as benzoyl peroxide, and dialkyl peroxides such as dicumyl peroxide. (E) Composition ratio The composition ratio of the inorganic filler to 100 parts by weight of the chlorinated polyethylene is 20 to 100 parts by weight, preferably 30 to 100 parts by weight, and particularly preferably 35 to 100 parts by weight. If the composition ratio of the inorganic filler to 100 parts by weight of chlorinated polyethylene is less than 20 parts by weight, a composition with excellent wear resistance and oil resistance cannot be obtained. On the other hand, if the amount exceeds 100 parts by weight, the moldability will be poor and even if a molded product is obtained, the flexibility will be poor, which is not preferable. In addition, the composition ratio of lead-containing inorganic compounds to 100 parts by weight of chlorinated polyethylene is
It is 25-30 parts by weight. If the composition ratio of the lead-containing inorganic compound to 100 parts by weight of chlorinated polyethylene is less than 25 parts by weight, a composition with good chemical resistance cannot be obtained. On the other hand, if it exceeds 30 parts by weight,
Although the resulting composition has excellent chemical resistance,
The moldability is poor and it is difficult to obtain a molded product with a uniform composition, and even if a molded product is obtained, it will not have good flexibility. (F) Mixing method, molding method, etc. Although the composition of the present invention can be obtained by uniformly blending the above substances,
Additionally, additives commonly used in the rubber and resin industries, such as fillers, plasticizers, oxygen, ozone, heat and light (ultraviolet) fixatives, lubricants, and colorants, may be added depending on the intended use of the composition. May be added. When producing the composition of the present invention, the blending (mixing) method may be to use a mixer commonly used in the art, such as an open roll, dry blender, Banbury mixer, or kneader. Among these mixing methods, in order to obtain a more uniform composition, two or more of these mixing methods may be applied (for example, after mixing in advance with a dry blender, the mixture may be mixed using an open roll). how to). The composition of the present invention may be molded into a dust seal using molding machines commonly used in the rubber industry, such as extrusion molding machines, injection molding machines, compression molding machines, and calender molding machines. In addition, a method of manufacturing a molded product while vulcanizing (crosslinking) it by adding chlorinated polyethylene or the above-mentioned composition and vulcanizing (crosslinking) it in the rubber technology field, that is, a method of simultaneously proceeding vulcanization and molding, is applied. It may be molded into a desired shape using a molding machine such as an extrusion molding machine, an injection molding machine, a compression molding machine, or a calendar molding machine that is used for molding into a desired shape. In addition, a method of manufacturing a molded product while vulcanizing (crosslinking) it by adding chlorinated polyethylene or the above-mentioned composition and vulcanizing (crosslinking) it in the rubber technology field, that is, a method of simultaneously proceeding vulcanization and molding, is applied. It may be formed into a desired shape. [] Examples and Comparative Examples The present invention will be explained in more detail below using Examples. In addition, in the Examples and Comparative Examples, the chemical resistance test was conducted using a test tube aging tester set at a temperature of 25°C, using 70% nitric acid as a liquid, and forming a JIS No. 3 dumbbell in it. The specimens were immersed and left for 7 and 14 days, respectively, and then measured using a Schover tester to measure the tensile strength (hereinafter referred to as "T _B "), elongation rate (hereinafter referred to as "E _B "), and hardness ( (hereinafter referred to as " _HS "), and the rate of change in T _B and E _B and the change in H _S were determined. Also,
Samples for volume change rate and weight change rate measurements were immersed under the same conditions as above, left for 7 days and 14 days, respectively. ”)
was measured. Note that ΔV and ΔW were measured using the Archimedes method. Furthermore, for the dimensional change test, each specimen was immersed under the same conditions as above, and each
After being left for 14 days, the dimensional change rate was measured using a low pressure caliper (pressure load: 80 g). The types and physical properties of each of the chlorinated polyethylene, inorganic filler, lead-containing inorganic compound, organic peroxide, crosslinking aid, and plasticizer used in Examples and Comparative Examples are shown below. [(A) Chlorinated polyethylene] As chlorinated polyethylene, the density is 0.941
g/ ^cm3 of ethylene polymer (average molecular weight approx. 25
Chlorinated polyethylene (chlorine content 40.2
Weight %, amorphous (hereinafter referred to as "CPE") was used. [(B) Inorganic filler] In addition, as an inorganic filler, Furnace Black (manufactured by Asahi Carbon Co., Ltd., trade name Asahi #50, average particle size
96 millimicrons, specific surface area 28 m ² /g, hereinafter referred to as "CB-1"), thermal black (manufactured by Asahi Carbon Co., Ltd., product name Asahi Thermal FT, average particle size
90 millimicrons, specific surface area 19 m ² /g, hereinafter referred to as "CB-2"), barium sulfate (density 4.5
g/cm ³ , average particle size 3.0 microns, hereinafter referred to as "BaSO ₄ "
), titanium oxide (density 4.0g/cm ³ , average particle size 0.3 microns, hereinafter referred to as "TiO ₂ "), and white carbon (density 2.0g/cm ³ , average particle size
0.5 micron) was used. For comparison, hydrated aluminum silicate (clay, density 2.6 g/cm ³ ,
Average particle size 0.3 μm, surface area approximately 20 m ² /g, pH 4.5 ~
5.5, hereinafter referred to as "Klee"). [(C) Lead-containing inorganic compound] Furthermore, as a lead-containing inorganic compound, lead oxide (manufactured by Shinagawa Kako Co., Ltd., density 9.4 g/cm ³ , average particle size 0.5
micron (hereinafter referred to as "PbO"), tribasic sulfate (manufactured by Koseisha, trade name TL4000, density approximately 7.0
g/cm ³ , average particle size 2.0 microns, hereinafter referred to as "tribase") and lead white (manufactured by Shinko Kagaku Co., Ltd., trade name lead white, density 6.8 g/cm ³ , average particle size 2.5 microns) were used. [(D) Organic peroxide] Dicumyl peroxide (hereinafter referred to as "DCP") was also used as an organic peroxide. [(E) Crosslinking aid] Triallylisocyanate (hereinafter referred to as "TAIC") was used as a crosslinking aid. [(F) Plasticizer] Furthermore, as a plasticizer, chlorinated paraffin (manufactured by Ajinomoto Co., trade name Shiopara K-45, chlorine content 45% by weight, density 1.17g/cm ³ , viscosity (25°C) 2
Poise (hereinafter referred to as "Salt Para") was used. Examples 1 to 10, Comparative Examples 1 to 7 100 parts by weight of chlorinated polyethylene, 15 parts by weight of salt para (plasticizer), 3 parts by weight of petroleum-based wax (manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd., trade name: Sannotsu, freezing point 65°C, as a lubricant), 5 parts by weight of DCP (organic peroxide) and 3 parts by weight of TAIC (crosslinking agent), as well as inorganic fillers and lead-containing inorganics whose types and amounts are shown in Table 1. A sheet was formed while kneading the compound for 20 minutes using an open roll whose surface temperature was preset at 50°C (in Comparative Examples 6 and 7, no lead-containing inorganic compound was blended). Each mixture thus obtained is heated to a temperature of 180°C.
A sheet was prepared by hot pressing for 15 minutes at a temperature of 200 kg/cm ² at a pressure of 200 kg/cm 2 . Chemical resistance tests, volume change rate and weight change rate tests, and dimensional change tests were conducted on each of the obtained sheets. The results are shown in Table 2. In this table, T _B and E _B are shown as change rates (unit: %), and H _S is shown as change (unit: points).

【table】

【table】

【table】

[Table] Note that in Comparative Examples 7 and 8, dehydrochlorination occurred during sheet manufacturing, and the sheet could not be manufactured. Comparative Examples 8 to 11 The types and amounts of the inorganic filler and lead-containing inorganic compound were changed as shown in Table 3.
A sheet was molded using an open roll in the same manner as in Example 1. Each mixture thus obtained was hot pressed in the same manner as in Example 1 to create a sheet. Chemical resistance tests, volume change rate and weight change rate tests, and dimensional change tests were conducted on each of the obtained sheets. those results in the fourth
Shown in the table.

【table】

[Table] From the results of the above examples and comparative examples, the chlorinated polyethylene composition obtained by the present invention is
It is clear that it has excellent chemical resistance (especially acid resistance) and dimensional stability, and is promising for the above-mentioned applications such as sealing materials and packing materials that require acid resistance.

Claims (1)

[Scope of Claims] 1 (A) Amorphous chlorinated polyethylene having a degree of chlorination of 30 to 45% by weight, obtained by chlorinating raw material polyethylene having a molecular weight of at least 150,000; (B) at least one inorganic filler selected from the group consisting of carbon black, synthetic white silicate carbon, barium sulfate, and titanium oxide; (C) consisting of lead oxides, hydroxides, and sulfates; It is a composition consisting of at least one lead-containing inorganic compound selected from the group consisting of at least one lead-containing inorganic compound and (D) an organic peroxide, and the composition ratio of the inorganic filler to 100 parts by weight of chlorinated polyethylene is 20 to 20 parts by weight.
100 parts by weight, and 25 to 30 parts by weight of lead-containing inorganic compounds, while the total amount of inorganic fillers and lead-containing inorganic compounds is at most 180 parts by weight, and organic peroxides 0.01 to 20.0 parts by weight. Chlorinated polyethylene.