JP2558034B2 - 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 thermoplastic elastomer composition having good compression set, low temperature characteristics, blocking resistance and excellent moldability.

[0002]

2. Description of the Related Art The demand for improved performance of elastomer materials is increasing year by year, and particularly in the automobile field, excellent compression set is required as a material for glass run channels, drainers, flush mount moldings and the like.
Conventionally, as these materials, soft vinyl chloride resin has a soft rubber-like feel, moldability, weatherability,
It has excellent colorability and the like, and has been widely used in terms of cost. However, compression set is inferior to vulcanized rubber, and the softening temperature is low, so that use at high temperatures is restricted. Therefore, attempts have been made to improve the vinyl chloride resin to have a high degree of polymerization, but no satisfactory one has been obtained.

There have been proposed various techniques for improving the compression set by adding a nitrile rubber having a crosslinked structure to a vinyl chloride resin. However, these compositions are inferior in processability, and have poor compression set and weather resistance. It was difficult to satisfy the properties at the same time. Further, an attempt to improve compression set by using chlorinated polyethylene and vinyl chloride resin as resin components is disclosed in JP-A-62-220547. It is essential to use a vinyl chloride resin and to crosslink the vinyl chloride resin, and if it is not crosslinked, sufficient compression set cannot be obtained. The technical idea of improving the compression set with a composition comprising a resin and a plasticizer is not disclosed. Further, this publication does not describe effects such as low temperature characteristics, blocking resistance, scratch resistance, and ease of molding.

The present inventors have previously found that a compounded composition with a specific chlorinated polyethylene and a plasticizer can improve physical properties such as compression set and weather resistance, and Japanese Patent Application No. 3-105.
No. 959 and Japanese Patent Application No. 3-151870,
Although these compositions are excellent in processability during kneading, since polyethylene with a relatively low molecular weight used for chlorination is selected, there is a problem of blocking due to oozing out of the plasticizer and low temperature characteristics. Etc., there are drawbacks to be further improved,
Depending on the application, it was not always satisfactory for practical use.

[0005]

DISCLOSURE OF THE INVENTION As a result of further intensive studies by the present inventors to improve compression set, low temperature characteristics, blocking resistance, and moldability, crystalline chlorinated polyethylene having a large DOP oil absorption amount. It has been found that a thermoplastic elastomer composition using as a resin component improves the above-mentioned various physical properties, and has completed the present invention. That is, an object of the present invention is to provide a thermoplastic elastomer composition having excellent compression set, low temperature characteristics, blocking resistance and moldability.

[0006]

The gist of the present invention is that the chlorination degree is 20 to 45%, the DSC method heat of fusion of crystals is 5
~ 35 cal / g, di-2-ethylhexyl phthalate (D
OP) as an oil component, 100 parts by weight of crystalline chlorinated polyethylene having a DOP oil absorption of 25 or more and a plasticizer 10 to 7
The thermoplastic elastomer composition contains 5 parts by weight as a main component.

The present invention will be described in detail. The crystalline chlorinated polyethylene used in the present invention has a chlorination degree of 20 to 45% and a DSC crystal fusion heat amount of 5 to 35 cal / g, preferably 5
It is necessary to be in the range of ˜25 cal / g, and this heat of fusion of crystal is in the range of 10 to 75%, preferably 10 to 50%, of the crystal residue of polyethylene, so-called crystallinity. DSC (Differential Scanning Calorimetry) What is the heat of crystal fusion? D measured using a differential calorimeter at a heating rate of 10 ° C / min.
It is a value calculated from the total crystal peak area of the SC chart, and if it is less than 5 cal / g, it indicates that there is substantially no residual crystal.

The DSC crystal melting point described later means DS
It is the temperature showing the highest peak of all the crystal peaks when measuring the heat of fusion of the C method crystal. 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, the hardness cannot be lowered, and the weather resistance is poor. On the other hand, if it exceeds 45%, the rubber elasticity decreases and the desired compression is achieved. Permanent strain and low temperature characteristics cannot be obtained. If the heat of fusion of crystal is less than 5 cal / g, the effect of improving compression set is lost, while if it exceeds 35 cal / g, the hardness cannot be lowered and the workability is remarkably poor.

The chlorinated polyethylene used in the present invention must have a DOP oil absorption of 25 or more. DO
The oil absorption amount of P means that the DOP is added little by little to 100 g of chlorinated polyethylene powder under the temperature condition of 23 ° C., and the mixture is stirred.
The added capacity of DOP which becomes lump-like mass of chlorinated polyethylene powder is expressed in ml. DOP oil absorption of 25 or more means D
It means that even if 25 ml of OP is added, it does not become a lump and is in the form of powder, or that it appears to be hardened and is dispersed by a slight force or impact. The measuring method is JIS
It carried out according to K5101. The chlorinated polyethylene currently on the market becomes a lump by the addition of 25 ml of DOP, and the DOP oil absorption is less than 25.

By using chlorinated polyethylene having a DOP oil absorption of 25 or more, the low temperature properties, blocking resistance and extrusion moldability of the resulting thermoplastic elastomer composition can be improved. The reason for this is not clear, but it is presumed that there are few low molecular weight substances or sticky substances in the crystalline chlorinated polyethylene, and therefore there is no phenomenon such as bleeding, and the adverse effects of bleeding of low molecular weight substances are small.

The plasticizer used in the present invention is not particularly limited as long as it is used for vinyl chloride resins.
For example, phthalate ester plasticizers such as di-2-ethylhexyl phthalate, di-n-octyl phthalate, diisodecyl phthalate, dibutyl phthalate, dihexyl phthalate; linear dibasic ester ester plasticizers such as dioctyl adipate and dioctyl sebacate; Trimellitic acid ester plasticizers; polyester polymer plasticizers; epoxy plasticizers such as epoxidized soybean oil, epoxidized linseed oil and epoxy resins; phosphoric acid such as triphenyl phosphate, trixylyl phosphate, tricresyl phosphate Ester-based plasticizers may be used, and one or more of these may be mixed and used.

The amount of the plasticizer used is appropriately determined depending on the additives used in combination or the hardness of the intended product.
It is selected from the range of 10 to 75 parts by weight, particularly 15 to 70 parts by weight, relative to 100 parts by weight of chlorinated polyethylene. When the amount of the plasticizer is in this range, the plasticizer is usually absorbed by the chlorinated polyethylene and is in a powder form, so that there is no obstacle to the kneading due to the blowing out of the plasticizer, and the kneading can be carried out extremely easily and uniformly.

The elastomer composition of the present invention may optionally contain a vinyl chloride resin. The vinyl chloride resin is a vinyl chloride homopolymer, a vinyl chloride-vinyl acetate copolymer, a vinyl chloride-ethylene copolymer, a vinyl chloride-ethylene-vinyl acetate copolymer or an ethylene-propylene copolymer, and vinyl chloride. Examples thereof include vinyl chloride-based graft copolymers obtained by graft polymerization, and commercially available products can be usually used. And the average degree of polymerization is J
The value measured based on IS K6721 is 400 to 400.
0, preferably 1000-3000, especially 1200-2
Those in the range of 500 are preferred. By adding a vinyl chloride resin to chlorinated polyethylene, the moldability is improved in combination with the action of the plasticizer, the low temperature characteristics are improved, and the bleeding phenomenon of the plasticizer is prevented.

The blending amount of the vinyl chloride resin is preferably smaller than that of chlorinated polyethylene, and it is desirable to keep it in the range of up to 80 parts by weight with respect to 100 parts by weight of chlorinated polyethylene. An inorganic filler can be added to the composition of the present invention within a range that does not impair the compression set. Examples of the filler include calcium carbonate and talc, which are used in an amount of 100 parts by weight or less, preferably 10 to 60 parts by weight, based on 100 parts by weight of chlorinated polyethylene. The inorganic filler has a function of absorbing an excessive amount of plasticizer and facilitating kneading.

The composition of the present invention preferably also contains a silicone compound. Silicone compounds reduce the drawback of chlorinated polyethylene, which is easily scratched,
The scratch resistance of the elastomer composition can be improved. As the silicone compound, polydimethylsiloxane, polymethylphenylsiloxane, polydiphenylsiloxane, polydimethylmethylphenylsiloxane,
Examples thereof include polydimethyl diphenyl siloxane and polymethyl hydrogen siloxane. The amount of the silicone compound added is 0.1 to 100 parts by weight of the resin component.
A range of 10 parts by weight is suitable. The thermoplastic elastomer composition of the present invention may optionally contain various additives such as stabilizers, lubricants, antioxidants, ultraviolet absorbers, foaming agents, flame retardants, pigments, impact modifiers, and the like. .

To produce the thermoplastic elastomer composition of the present invention, the crystalline chlorinated polyethylene and the plasticizer and, if necessary, the above-mentioned various additives are heated to a temperature above the crystalline melting point of the crystalline chlorinated polyethylene. However, it is desirable to knead under shearing force. By kneading under these conditions, an elastomer composition having excellent compression set and low temperature characteristics can be obtained. At temperatures below the crystalline melting point, the plasticizer penetrates only into the amorphous portion of the crystalline chlorinated polyethylene and the crystal structure after kneading does not change much, but it is heated to a temperature above the crystalline melting point and kneaded under shearing force. It is presumed that the plasticizer penetrates into the crystal part as well, and when the chlorinated polyethylene is recrystallized, a new network structure between the molecular chains is generated and the rubber elasticity such as compression set is improved. Is done. Further, when the molecular weight of the crystalline chlorinated polyethylene becomes large, it is presumed that a large amount of plasticizer can be included in the molecular chain, so that the blocking resistance is improved and the low temperature characteristics are also improved.

The equipment used to mix the above-described ingredients may be any equipment that allows for substantially uniform mixing, such as a Henschel mixer, ribbon blender,
A planetary mixer or the like can be used. To knead the mixture, for example, an extruder, roll, Banbury mixer, kneader, or other device capable of kneading under heating while being heated is used. As a kneading method, it is also possible to adopt a method in which a chlorinated polyethylene and various additives are charged in the former stage and an plasticizer is injected in the latter stage using an extruder having multi-stage addition ports. The upper limit of the heating temperature is preferably within a range where thermal deterioration of the chlorinated polyethylene can be ignored, specifically, 210 ° C. or less. The kneading temperature is in the range of 130 to 210 ° C, preferably 150 to 200 ° C.

[0018]

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 of the present invention. In addition, "part" and "%" in the examples
Is by weight unless otherwise noted. Further, the quality evaluation of the thermoplastic elastomer composition was performed as follows, and is shown in Table 3.

Hardness: A test piece similar to that used for measuring compression set was measured according to JIS K6301 [JIS A hardness]. Measurement of compression set: 70 based on JIS K6301
Measured at 25 ° C for 22 hours at 25 ° C. Low temperature characteristics: In a low temperature torsion test method based on JIS K6301, the apparent torsional modulus is 1.0 × 10 ^3.
kg / cm ² .

Blocking resistance: 1 mm thick sheet (20 mm
X 100 mm) were stacked and heat-treated at 40 ° C for 2 hours, and then left at 20 ° C for 30 minutes. The degree of peeling of the two-ply sheet was evaluated by the following three grades by touch. ◯: Peeling is good Δ: Peeling is difficult or difficult X: Adhesion does not occur and peeling does not occur. Formability: An L-shaped die was attached to a 40 mm extruder (L / D = 24), and profile extrusion was performed at a die temperature of 180 ° C. The surface condition or edge breakage of the molded product was visually evaluated. ：: Good surface condition and no edge cut △: Poor surface condition or edge cut ×: Bad surface condition and remarkable edge cut

Strain recovery: Autograph (DCS-200
Type 0, manufactured by Shimadzu Corporation) is used. 1mm thickness, 5mm width, 100
Attach a 50 mm mark to a mm-long sheet piece, and perform 10 at 23 ° C.
200% elongation at a speed of 00 mm / min.
Hold for 0 minutes. Thereafter, the sheet piece was removed from the chuck, and after 30 seconds, the dimension between the marked lines was measured, and the recovery rate was calculated from the value by the following equation. [1- (L-L ₀ ) / L ₀ ] × 100 (%) L ₀ : initial length (50 mm), L: length after test

Examples 1 to 7 and Comparative Examples 1 to 4 Chlorinated polyethylene (CPE) of the types and addition amounts (parts by weight) shown in Table 1, plasticizer, vinyl chloride resin (PV
C), an inorganic filler (filler), a silicone compound, and 2 parts of a lead-based powder stabilizer are mixed in a Henschel mixer at room temperature for 3 minutes, and the mixture is kneaded at 85 rpm in a Banbury mixer at a jacket temperature of 160 ° C. for 3 minutes. Then, the mixture was kneaded with a mill roll having a surface temperature of 150 ° C. for 3 minutes to obtain a 2 mm thick sheet. This sheet was further pressed at 180 ° C. for 5 minutes to prepare a test piece having a predetermined thickness. The quality evaluation described above was performed on this test piece. In order to evaluate the moldability, 2
The sheet having a thickness of mm was formed into pellets by a sheet cutting method and then subjected to extrusion molding. The raw materials used in the examples are shown in Table 2.
Are summarized in. CPE is provided by Showa Denko KK
Was offered.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

[Table 3]

In addition to the above evaluation results, Examples 3 and 7 in which PVC was mixed exhibited good scratch resistance, and Example 5 containing a silicone compound also showed an effect of improving scratch resistance.

[0027]

INDUSTRIAL APPLICABILITY In the thermoplastic elastomer composition of the present invention, by adding a plasticizer to crystalline chlorinated polyethylene having specific plasticizer absorption characteristics, compression set and low temperature characteristics are improved, and blocking resistance is further improved. The workability is also good, and the processability is improved by the combined use of the inorganic filler. Further, the composition of the present invention, by kneading under shearing force at a temperature equal to or higher than the crystalline melting point of chlorinated polyethylene, dramatically improves compression set without adding a vulcanizing agent or a crosslinking agent. And the low temperature characteristics can be improved at the same time. The composition of the present invention is extremely useful as a raw material for wind moldings, glass run channels, drainers, boots, etc., which are mounted on automobiles, and in fields requiring rubber elasticity such as packing.

Claims (4)

(57) [Claims] 1. A crystalline chlorinated polyethylene 100 having a chlorination degree of 20 to 45%, a DSC heat of fusion of crystals of 5 to 35 cal / g, and a DOP oil absorption of 25 or more using di-2-ethylhexyl phthalate (DOP) as an oil component. A thermoplastic elastomer composition containing, as main components, 10 parts by weight and 10 to 75 parts by weight of a plasticizer. 2. The thermoplastic elastomer composition according to claim 1, which contains a vinyl chloride resin. 3. The thermoplastic elastomer composition according to claim 1, which contains an inorganic filler. 4. The method according to claim 1, which contains a silicone compound.
The thermoplastic elastomer composition according to claim 2 or 3.