JPH08269273A - Production of thermoplastic elastomer composition - Google Patents

Abstract

PURPOSE: To obtain a thermoplastic elastomer compsn. excellent in creep characteristics by mixing a crystalline chlorinated polyethylene with a specific plasticizer while adding the plasticizer continuously or intermittently to the resin. CONSTITUTION: PE having a wt. average mol.wt. of 100,000-750,000 is chlorinated to give a crystalline chlorinated polyethylene having a degree of chlorination of 20-45wt.% a heat of crystal fusion by DSC of 5-35cal/g, and a di-2-ethylhexyl phthalate absorption (according to JIS 5101) of 25 or higher. 100 pts.wt. chlorinated polyethylene is dry blended with 400 pts.wt. or lower, pref. 200 pts.wt. or lower, thermoplastic resin (e.g. a vinyl chloride resin) by a Henschel mixer, etc., to give a dry blend. Then, 60-200 pts.wt. plasticizer (e.g. di-2-ethylhexyl phthalate) is added continuously or intermittently to the dry blend, if necessary together with other additives, and the blend is then kneaded at about 130-210 deg.C by a Banbury mixer, etc., and extruded with a twin-screw extruder to be palletized, giving a thermoplastic elastomer compsn.

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 which is excellent in creep properties (compression set) and low temperature specification 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, etc., but as the years progress, thermoplastic elastomer materials with improved performance have been developed. There is. The applicant of the present invention first disclosed in Japanese Patent Laid-Open No. 4-335 for the purpose of improving creep characteristics and low temperature characteristics.
047, JP-A-5-1187, and JP-A-5-247290.
Have proposed an elastomer composition comprising a specific chlorinated polyethylene and a plasticizer.

However, the elastomer composition of the invention described above has a JIS A hardness of less than 60 because it is difficult to knead it when a large amount of a plasticizer is added to chlorinated polyethylene during its production and the amount of the plasticizer added is limited. It was difficult to produce a hard elastomer composition. When a large amount of a plasticizer is added, it is kneaded with other additives such as an inorganic filler that easily absorbs the plasticizer, but problems such as aggregation or sticking occur and commercial production is extremely difficult.

[0004]

DISCLOSURE 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 application of the elastomer composition comprising chlorinated polyethylene and a plasticizer. However, as a result of earnest studies to develop the composition, by mixing or kneading the plasticizer into the chlorinated polyethylene in two or more times, mixing or kneading does not cause problems such as agglomeration and tackiness, and easily achieves low hardness. The inventors have found that an elastomer composition can be obtained and completed the present invention. 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 is characterized in that the crystalline chlorinated polyethylene is mixed while continuously or intermittently adding a plasticizer.

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.
It is desirable to be in the range of wt% and heat of fusion of DSC method crystals of 5 to 35 cal / g. The DSC method crystal fusion heat is a value calculated from the crystal peak area of a DSC chart measured at a temperature rising rate of 10 ° C./min using a differential calorimeter, and 5 ca
If it is less than 1 / g, there is substantially no residual crystal. Further, the DSC method crystal melting point described later is the temperature at which the highest peak among all the crystal peaks at the time of DSC method crystal fusion heat measurement is shown. 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 chlorinated polyethylene is less than 20%, the compatibility with the plasticizer is poor and it is difficult to obtain rubber elasticity. 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,
When the heat of crystal fusion is less than 5 cal / g, the effect of improving the creep characteristics is apt to be lost, while when it exceeds 35 cal / g, it becomes difficult to lower the hardness, and the absorption amount of the plasticizer during mixing and kneading becomes small, and kneading is carried out. Processing is difficult, the compatibility with the plasticizer at room temperature is poor, and the bleeding phenomenon easily occurs.

The chlorinated polyethylene used in the method for producing the thermoplastic elastomer composition of the present invention preferably has a weight average molecular weight in the range of 10 to 750,000 before chlorination. As the polyethylene has a higher molecular weight, not only the physical properties such as tensile strength and compression set are improved, but also the ability to include the plasticizer is increased, so that a large amount of the plasticizer can be added, which leads to a low hardness. Easy to obtain composition. On the other hand, if the molecular weight is 100,000 or less, the plasticizer absorbability is small, and it is difficult to obtain a composition having a low hardness. The molecular weight of polyethylene shows the value of the weight average molecular weight measured by GPC (gel permeation chromatography).

Chlorinated polyethylene is D-2-ethylhexyl phthalate (DOP) when used as an oil.
It is desirable that the OP oil absorption is 25 or more. It is preferably 50 or more. DOP oil absorption is the amount of DOP added at 100 ml of chlorinated polyethylene powder at a temperature of 23 ° C. while adding DOP little by little and stirring to give a lump of chlorinated polyethylene powder. A value of 25 or more means that it does not become a lump even after adding 25 ml of DOP and is in the form of powder, and that it appears to be hardened and is dispersed by a slight force or impact. The measuring method was based on 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 vinyl chloride resins, and examples thereof include di-2-ethylhexyl phthalate, di-n-octyl phthalate, diisodecyl phthalate, Phthalate ester plasticizers such as dibutyl phthalate and dihexyl phthalate; Linear dibasic acid ester plasticizers such as dioctyl adipate and dioctyl sebacate; Biphenyl tetracarboxylic acid alkyl ester plasticizers such as biphenyl tetracarboxylic acid tetraheptyl ester Trimellitic acid ester plasticizers; polyester polymer plasticizers; epoxy plasticizers such as epoxidized soybean oil, epoxidized linseed oil, epoxy resin; triphenyl phosphate, trixylyl phosphate, tricresyl phosphate, etc. Phosphate ester plasticizer and the like, used as a mixture of at least these one or two. The amount of plasticizer used is appropriately determined depending on the desired hardness,
Chlorinated polyethylene 10 to obtain molded products with low hardness
60 to 200 parts by weight is necessary with respect to 0 parts by weight, and particularly preferably 75 to 160 parts by weight. If the amount of the plasticizer is too small, a low hardness cannot be obtained. On the contrary, if the amount of the plasticizer is too large, the moldability becomes poor and it is difficult to suppress the bleeding phenomenon.

It is desirable to add an inorganic filler or a thermoplastic resin or a rubber substance having a good affinity with the plasticizer to the thermoplastic elastomer composition for the purpose of preventing the bleeding phenomenon and accelerating the mixing or kneading. The amount of these used is appropriately determined depending on the amount of the plasticizer used, but is usually 400 parts by weight or less, preferably 200 parts by weight, particularly preferably 100 parts by weight or less with respect to 100 parts by weight of chlorinated polyethylene. is there. Examples of the inorganic filler include general 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 rubber substance is, for example, nitrile. -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.
The above-mentioned inorganic filler, thermoplastic resin or rubber substance may be used alone or in combination of two or more, if necessary. further,
The thermoplastic elastomer composition may optionally contain various additives such as stabilizers, lubricants, antioxidants, ultraviolet absorbers, foaming agents, flame retardants, pigments and impact modifiers.

The method of the present invention is to produce a thermoplastic elastomer composition by mixing a crystalline chlorinated polyethylene with a plasticizer continuously or intermittently. The method for producing the elastomer composition is not particularly limited, but for example, crystalline chlorinated polyethylene and a part of the plasticizer, preferably crystalline chlorinated polyethylene 10
Mixer such as Henschel mixer, ribbon blender, planetary mixer, etc. with less than 60 parts by weight relative to 0 parts by weight and, if necessary, other additives such as inorganic fillers, thermoplastic resins, rubber substances and stabilizers. Into a dry chlorinated polyethylene, the crystalline chlorinated polyethylene is sufficiently absorbed with a plasticizer, so-called dry blending is performed, and then the remaining plasticizer is continuously or intermittently added to the dry blended product to obtain a uniform mixture. Continue with the dry blend. The maximum amount of plasticizer that can be added during dry blending is about 120 parts by weight. Further, an additive having an affinity with the plasticizer such as an inorganic filler, a thermoplastic resin, or a rubber substance may be added from the beginning, but it is preferably added after the remaining plasticizer is added to the dry blend. Is preferable because it facilitates the dry blending operation. 12 during dry blending
If 0 part by weight or more of a plasticizer is added, the compound is likely to agglomerate, resulting in poor dry blending workability.

The method of the present invention may be a kneading process of the dry blend so-called thermoplastic elastomer composition prepared as described above. For kneading, an extruder, a Banbury mixer, a kneader, or other device capable of stirring under shear while heating is used. By the kneading operation, a larger amount of 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 all at once during kneading, or intermittently or continuously.

The heating temperature at the time of kneading is a temperature above the crystalline melting point of crystalline chlorinated polyethylene and within a range where its deterioration can be ignored, specifically 210 ° C. or less, preferably 13
It is preferably in the range of 0 to 210 ° C, particularly 140 to 200 ° C. The elastomer composition after kneading is pelletized by a sheet cutting method or a hot cutting method and used. When the temperature at the time of kneading is lower than the crystal melting point, the plasticizer penetrates only into the amorphous part 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 interchain network structure is generated during recrystallization, which improves rubber elasticity such as compression set and facilitates incorporation of the plasticizer between the molecular chains. It is estimated that the hardness becomes low because more plasticizer can be added.

[0016]

INDUSTRIAL APPLICABILITY According to the method of the present invention, a large amount of a plasticizer can be contained in crystalline chlorinated polyethylene by blending the plasticizer continuously or intermittently. The plastic elastomer composition exhibits excellent compression set, low temperature characteristics, and 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 with hardness less than A hardness 60,
For example, it can be effectively used for building materials such as hoses, pipes, sheets, gaskets, materials for interior and exterior of automobiles such as weather strips, side moldings, shift lever boots, and sports equipment materials such as grips for skis and grips for 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 without departing from the gist thereof. In addition, "part" and "%" in the examples 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 blend processability A Henschel mixer was used as a mixer and the state of heat mixing was visually determined. ◯: No aggregation or tackiness and good workability Δ: Slightly agglomeration or tackiness on the wall X: Aggregation or sticking prevents discharge. Hardness Based on JIS K6301. 23 ° C
The value after 10 seconds was measured using an A type hardness meter. Tensile properties Based on JIS K6301. Using No. 3 dumbbell, measured at a pulling speed of 200 mm / min,
It is shown in tensile strength and elongation. Compression set Based on JIS K6301. 70 ° C
It was measured under a condition of 25% compression for 22 hours. Low temperature characteristics In the low temperature torsion test method based on JIS K6301, the apparent torsion modulus is 3.1.
The temperature is 7 × 10 ³ kg / cm ² .

Examples 1 to 8 and Comparative Examples 1 to 4 100 parts of crystalline chlorinated polyethylene and a plasticizer are shown in Table-1.
1 divided charge and barium-zinc stabilizer 2
A part was put into a Henschel mixer and stirred to absorb the plasticizer into the crystalline chlorinated polyethylene. Next, dry blending was completed by sequentially adding the divided charge amounts of plasticizer shown in Table 1 for two and three times. A filler or a rubber substance was further added to this dry blend and mixed by stirring. The final reached resin temperature for 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 charging amount of the plasticizer were added during the kneading. The maximum resin temperature during kneading is
Although it depends on each embodiment, all are from 169 ° C. to 18
The temperature was between 6 ° C. Then, the kneaded product was formed into a sheet with a mill roll, and then this sheet was press-molded 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 during the kneading. The raw materials used in the examples are as follows.

[0022]

[Table 2] Crystalline chlorinated polyethylene A: pre-chlorination polyethylene molecular weight 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 Polyethylene molecular weight before chemical conversion 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 characteristics and has low hardness. As in Comparative Examples 1 to 3, the crystalline chlorinated polyethylene to which the plasticizer was added all at once could not be discharged due to aggregation or adhesion in the mixer tank during dry blending, and various physical properties were not evaluated. Further, in Comparative Example 4 in which the plasticizer was added only at the time of kneading, the plasticizer was not properly absorbed by the chlorinated polyethylene, resulting in non-uniformity, which made the kneading difficult.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Kawakami 2 Oike, Iwazuka-cho, Nakamura-ku, Nagoya-shi, Aichi Mitsubishi Chemical MKV Co., Ltd. Nagoya Office

Claims (7)

[Claims] 1. 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, wherein the plasticizer is continuously added to the crystalline chlorinated polyethylene. Alternatively, the method for producing a thermoplastic elastomer composition is characterized in that mixing is performed while intermittently adding. 2. The crystalline chlorinated polyethylene has a chlorination degree of 2.
0 to 45% by weight, DSC crystal heat of fusion 5 to 35 cal
The method for producing the thermoplastic elastomer composition according to claim 1, wherein the thermoplastic elastomer composition 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 10 to 750,000. 4. The thermoplastic elastomer composition according to claim 1, 2 or 3, wherein the crystalline chlorinated polyethylene has an oil absorption of 25 or more when di-2-ethylhexyl phthalate is used as an 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, which contains a rubber substance. 7. The method for producing a thermoplastic elastomer composition according to claim 1, which contains a vinyl chloride resin.