JP2970464B2 - Method for producing thermoplastic elastomer composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a low-hardness thermoplastic elastomer composition having excellent creep properties (compression set) and low-temperature characteristics without vulcanization or crosslinking.

[0002]

2. Description of the Related Art In recent years, thermoplastic elastomer materials have been used in various fields such as building materials, automobile interior materials, exterior materials, and the like. I have. The present applicant has previously disclosed Japanese Patent Application Laid-Open No. 4-335 for the purpose of improving creep characteristics and low-temperature characteristics.
047, JP-A-5-1187, JP-A-5-247290
And the like have proposed an elastomer composition comprising a specific chlorinated polyethylene and a plasticizer.

However, the elastomer composition of the present invention is difficult to knead when a large amount of a plasticizer is added to chlorinated polyethylene during its production, and the JIS A hardness is lower than 60 because the amount of the plasticizer added is limited. It was difficult to produce an elastomer composition having a hardness. When a large amount of a plasticizer is added, it is kneaded with other additives such as an inorganic filler which can easily absorb the plasticizer. However, problems such as agglomeration or stickiness occur, and commercial production has been extremely difficult.

[0004]

SUMMARY OF THE INVENTION The present inventors have realized that it is necessary to develop an elastomer composition having a low hardness in order to expand the field of use of an elastomer composition comprising chlorinated polyethylene and a plasticizer. However, as a result of diligent studies to develop the composition, the chlorinated polyethylene is divided into two or more times and mixed or kneaded, so that problems of aggregation and sticking do not occur, and low hardness can be easily obtained. It has been found that an elastomer composition can be obtained, and the present invention has been completed. An object of the present invention is to provide a method for producing a low-hardness thermoplastic elastomer composition having excellent creep properties, low-temperature properties, and processability.

[0005]

The gist of the present invention is to provide a method for producing a thermoplastic elastomer composition comprising 100 parts by weight of crystalline chlorinated polyethylene and 60 to 200 parts by weight of a plasticizer as essential components. A method for producing a thermoplastic elastomer composition, characterized in that a plasticizer is continuously or intermittently added to the crystalline chlorinated polyethylene and mixed.

The present invention will be described in detail. The crystalline chlorinated polyethylene used in the method of the present invention has a chlorination degree of 20 to 45.
% By weight and the heat of fusion of the crystal by the DSC method is preferably in the range of 5 to 35 cal / g. The DSC method crystal heat of fusion is a value calculated from the crystal peak area of the DSC chart measured at a heating rate of 10 ° C./min using a differential calorimeter.
Less than 1 / g indicates that there is substantially no residual crystal. In addition, the DSC crystal melting point described later is a temperature at which the highest peak among all crystal peaks at the time of DSC crystal melting heat measurement is obtained. The crystalline melting point of the chlorinated polyethylene used in the present invention is in the range of 110 to 140 ° C.

If the degree of chlorination of the chlorinated polyethylene is less than 20%, the compatibility with the plasticizer is inferior, and rubber elasticity is hardly obtained. On the other hand, if it exceeds 45%, the rubber elasticity decreases and the desired good creep properties ( C.S.) is difficult to obtain. Also,
If the heat of crystal fusion is less than 5 cal / g, the effect of improving the creep properties tends to be lost, while if it exceeds 35 cal / g, it becomes difficult to lower the hardness, and the amount of plasticizer absorbed during mixing and kneading decreases, resulting in kneading. Processing is difficult, the compatibility with the plasticizer at normal temperature is poor, and the bleeding phenomenon is likely to occur.

The chlorinated polyethylene used in the method for producing the thermoplastic elastomer composition of the present invention preferably has a weight average molecular weight of 100,000 to 750,000 before chlorination. As polyethylene has a higher molecular weight, not only physical properties such as tensile strength and compression set are improved, but also the ability to include a plasticizer is increased, so that a large amount of plasticizer can be added, and as a result, low hardness is obtained. Easy to obtain composition. On the other hand, a composition having a small molecular weight of 100,000 or less has a low plasticizer absorption ability, so that it is difficult to obtain a composition having low hardness. The molecular weight of polyethylene indicates the value of the weight average molecular weight measured by GPC (gel permeation chromatography).

When chlorinated polyethylene uses di-2-ethylhexyl phthalate (DOP) as an oil,
Those having an OP oil absorption of 25 or more are desirable. Preferably it is 50 or more. The amount of DOP oil absorption is the amount of DOP added in ml, which is obtained by adding DOP little by little to 100 g of chlorinated polyethylene powder and stirring at a temperature of 23 ° C. to form a lumped chlorinated polyethylene powder. The term “25 or more” means a powder which does not clump even when 25 ml of DOP is added and exhibits a powdery state, and which disperses with a slight force or impact even if it appears to be solidified. The measuring method conformed to JIS K5101.

The plasticizer which is an essential component of the method of the present invention is not particularly limited as long as it is used for a vinyl chloride resin. For example, di-2-ethylhexyl phthalate, di-n-octyl phthalate, diisodecyl phthalate, Phthalate ester plasticizers such as dibutyl phthalate and dihexyl phthalate; linear dibasic ester plasticizers such as dioctyl adipate and dioctyl sebacate; biphenyltetracarboxylic acid alkyl ester plasticizers such as biphenyltetracarboxylic acid tetraheptyl ester Trimellitic ester plasticizers; Polyester polymer plasticizers; Epoxy plasticizers such as epoxidized soybean oil, epoxidized linseed oil, and epoxy resin; Triphenyl phosphate, trixylyl phosphate, and tricresyl phosphate; Phosphate ester plasticizer and the like, used as a mixture of at least these one or two. The amount of the plasticizer used is appropriately determined depending on the desired hardness,
Chlorinated polyethylene 10
60 to 200 parts by weight per 0 parts by weight is necessary, and particularly preferably 75 to 160 parts by weight. If the amount of the plasticizer is too small, a material having low hardness cannot be obtained. If the amount is too large, the moldability is poor, and it is difficult to suppress the bleeding phenomenon.

It is desirable to add a thermoplastic resin or a rubber material having a good affinity for an inorganic filler, a plasticizer, for the purpose of preventing bleeding and speeding up mixing or kneading to the thermoplastic elastomer composition. These amounts are appropriately determined depending on the amount of the plasticizer used, but are usually 400 parts by weight or less, preferably 200 parts by weight, and particularly preferably 100 parts by weight or less, based on 100 parts by weight of the chlorinated polyethylene. is there. Examples of the inorganic filler include common inorganic powders such as calcium carbonate, clay, and talc.

The thermoplastic resin having an affinity for the plasticizer is selected from, for example, vinyl chloride resin, vinyl chloride-vinyl acetate copolymer, chlorinated vinyl chloride resin, vinylidene chloride resin and the like. -Butadiene rubber (NBR), acrylic rubber (AR), methyl methacrylate-butadiene-styrene copolymer (MB
S), styrene-butadiene rubber (SBR), ethylene-vinyl acetate copolymer (EVA), chloroprene rubber (CR), urethane rubber (PU), chlorosulfonated polyethylene (CSM), epichlorohydrin rubber (C
O), amorphous chlorinated polyethylene and the like.
One or more of the above-mentioned inorganic fillers, thermoplastic resins or rubber substances may be used, if necessary. further,
If necessary, various additives such as a stabilizer, a lubricant, an antioxidant, an ultraviolet absorber, a foaming agent, a flame retardant, a pigment, and an impact modifier may be added to the thermoplastic elastomer composition.

The method of the present invention consists in producing a thermoplastic elastomer composition by mixing a plasticizer with crystalline chlorinated polyethylene continuously or intermittently. The method for producing the elastomer composition is not particularly limited. For example, crystalline chlorinated polyethylene and a part of a plasticizer, preferably crystalline chlorinated polyethylene 10
A blender such as a Henschel mixer, a ribbon blender, a planetary mixer or the like, in which an amount of less than 60 parts by weight per 0 parts by weight and other additives such as an inorganic filler, a thermoplastic resin, a rubber substance, and a stabilizer are added as required. Into the chlorinated polyethylene, so that the plasticizer is sufficiently absorbed by the so-called dry blending, and then the remaining plasticizer is continuously or intermittently added to the dry blended product. Continue dry blending. The maximum amount of plasticizer that can be added during dry blending is about 120 parts by weight. In addition, additives having an affinity for a plasticizer such as an inorganic filler, a thermoplastic resin, and a rubber substance may be added from the beginning, but are preferably added after the remaining plasticizer is added to the dry blend. This is desirable because it facilitates the dry blending operation. 12 during dry blending
If 0 parts by weight or more of the plasticizer is added, the composition is likely to aggregate, and the dry blending workability is deteriorated.

In the method of the present invention, the dry blend prepared as described above may be kneaded with a so-called thermoplastic elastomer composition. For kneading, an extruder, a Banbury mixer, a kneader or the like which can be stirred under shearing force while heating is used. By the kneading operation, a larger amount of the plasticizer can be contained in the elastomer composition.
That is, the remaining plasticizer that could not be mixed by the dry blending operation can be added at once during the kneading, intermittently, or continuously.

The heating temperature during kneading is a temperature not lower than the crystal melting point of the crystalline chlorinated polyethylene and within a range where its deterioration can be ignored, specifically 210 ° C. or lower, preferably 13 ° C.
It is preferably in the range of 0 to 210 ° C, particularly 140 to 200 ° C. The kneaded elastomer composition is pelletized and used by a sheet cut method or a hot cut method. If the temperature during kneading is lower than the crystal melting point, the plasticizer penetrates only into the amorphous portion of the crystalline chlorinated polyethylene, and the crystal structure does not change much. By kneading,
The plasticizer also penetrates into the crystal part, and a new intermolecular network structure is formed during recrystallization, improving rubber elasticity such as compression set and making it easier for the plasticizer to be incorporated between molecular chains. It is assumed that the hardness becomes low because more plasticizer can be blended.

[0016]

According to the method of the present invention, a large amount of the plasticizer can be contained in the crystalline chlorinated polyethylene by continuously or intermittently blending the plasticizer. The plastic elastomer composition is excellent in compression set, low-temperature properties, and shows low hardness by undergoing a kneading step or a kneading step during molding.

Therefore, the thermoplastic elastomer composition produced by the method of the present invention has a low hardness, especially JIS
As a raw material for molded products having a hardness smaller than A hardness 60,
For example, it can be effectively used as architectural materials such as hoses, pipes, sheets, and gaskets, materials for automobile interiors and exteriors such as weather strips, side moldings, and shift lever boots, and materials for sports equipment such as grips for ski poles and rackets.

[0018]

EXAMPLES Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples unless departing from the gist thereof. In the examples, “parts” and “%” are based on weight unless otherwise specified. The quality evaluation of the thermoplastic elastomer composition was performed as follows and shown in Table 1.

[0019]

Table 1 Dry blending processability The state of heating and mixing using a Henschel mixer as a mixer was visually determined. ：: Good workability without aggregation or stickiness △: Slightly aggregated or sticky to wall ×: Aggregated or not discharged due to adhesion Hardness Based on JIS K6301. 23 ℃
The value after 10 seconds was measured using an A-type hardness tester. Tensile properties Based on JIS K6301. Using a No. 3 dumbbell, measure at a tensile speed of 200 mm / min,
The values are shown as tensile strength and elongation. Compression set Based on JIS K6301. 70 ° C
× 22 hours, measured under 25% compression conditions. Low temperature characteristics In the low temperature torsion test method based on JIS K6301, the apparent torsional modulus is 3.1.
The temperature was shown at 7 × 10 ³ kg / cm ² .

Examples 1 to 8 and Comparative Examples 1 to 4 A plasticizer was added to 100 parts of crystalline chlorinated polyethylene, as shown in Table 1.
And the barium-zinc stabilizer 2
The part was charged into a Henschel mixer and stirred to absorb the plasticizer into the crystalline chlorinated polyethylene. Next, the divided amounts of the plasticizer shown in Table 1 for the second and third batches were sequentially added to complete the dry blending. A filler or a rubber substance was further added to the dry blend, followed by stirring and mixing. The final resin temperature of the final dry-up was 100 ° C.

The powdery elastomer composition thus prepared was transferred to a Banbury mixer having a jacket temperature of 100 ° C. and kneaded. Four times of the divided charge of the plasticizer were added during kneading. The maximum resin temperature during kneading is
Although it differs according to each embodiment, in each case, the temperature is from 169 ° C to 18 ° C.
The temperature was between 6 ° C. Next, a sheet was prepared from the kneaded material using a mill roll, and the sheet was press-formed at 180 ° C. to prepare a predetermined test piece, which was subjected to each quality evaluation test. In Comparative Examples 1 to 3, the kneading operation was not performed, and in Comparative Example 4, the plasticizer was added only at the time of kneading. The raw materials used in the examples are as follows.

[0022]

[Table 2] Crystalline chlorinated polyethylene A: polyethylene molecular weight before chlorination: 350,000, (CPE) chlorination degree: 31%, heat of crystal fusion: 8.3 cal / g, crystal melting point: 118 ° C, DOP oil absorption: 50 or more B: chlorine Unmodified polyethylene molecular weight 200,000, chlorination degree 31%, heat of crystal fusion 10.9 cal / g Crystal melting point 125 ° C, DOP oil absorption 50 or more Plasticizer (DOP) Di-2-ethylhexyl phthalate Filler (CaCO ₃ ) Heavy Calcium carbonate Rubber substance (NBR) Acrylonitrile content 40%

[0023]

[Table 3]

As is clear from the results shown in Table 1, the elastomer composition obtained by the method of the present invention is excellent in compression set and low-temperature properties and has low hardness. As in Comparative Examples 1 to 3, crystalline plasticized chlorinated polyethylene to which a plasticizer was added at one time could not be discharged due to coagulation or sticking in a mixer tank during dry blending, and various physical properties were not evaluated. Further, in the case where the plasticizer was added only at the time of kneading as in Comparative Example 4, the plasticizer was not well absorbed by the chlorinated polyethylene and became uneven, making kneading difficult.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI (C08L 23/28 27:06) (72) Inventor Takashi Kawakami 2 Oike, Iwatsukacho, Nakamura-ku, Nagoya-shi, Aichi Mitsubishi Chemical MKV Corporation Nagoya office (58) Field surveyed (Int.Cl. ⁶ , DB name) C08J 3/00-3/28 C08L 23/00-23/36

Claims (7)

(57) [Claims] 1. A method for producing a thermoplastic elastomer composition comprising 100 parts by weight of a crystalline chlorinated polyethylene and 60 to 200 parts by weight of a plasticizer, wherein a plasticizer is continuously added to the crystalline chlorinated polyethylene. Alternatively, a method for producing a thermoplastic elastomer composition, which comprises mixing while adding intermittently. 2. The crystalline chlorinated polyethylene has a chlorination degree of 2.
0 to 45% by weight, DSC crystal heat of fusion 5-35 cal
The method for producing a thermoplastic elastomer composition according to claim 1, which is in the range of / g. 3. The method for producing a thermoplastic elastomer composition according to claim 1, wherein the weight average molecular weight of the crystalline chlorinated polyethylene before chlorination is 100,000 to 750,000. 4. The thermoplastic elastomer composition according to claim 1, wherein the crystalline chlorinated polyethylene has an oil absorption of 25 or more when di-2-ethylhexyl phthalate is used as the oil. Production method. 5. The method for producing a thermoplastic elastomer composition according to claim 1, further comprising an inorganic filler. 6. The method for producing a thermoplastic elastomer composition according to claim 1, further comprising a rubber substance. 7. The method for producing a thermoplastic elastomer composition according to claim 1, further comprising a vinyl chloride resin.