JPH0431452A - Thermoplastic elastomer composition and its production - Google Patents

Abstract

PURPOSE:To obtain the title composition which can give a molding to which low compression set is imparted and which need not be vulcanized, is extrusion- moldable or injection-moldable and can give a noncracking molding by adding a methyl methacrylate resin to a specified thermoplastic elastomer composition. CONSTITUTION:A methyl methacrylate resin is added to an elastomer composition prepared by mixing a plasticized vinyl chloride resin with a silicone resin and an acrylonitrile/butadiene rubber. In this way, a vinyl chloride resin thermoplastic elastomer composition which can give a noncracking molding when extrusion-molded, can give a molding to which low compression set is imparted and which need not be vulcanized and is extrusion-moldable or injection- moldable can be obtained.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a molded product made of vinyl chloride resin, silicone resin, methyl methacrylate resin, and acrylonitrile rubber (hereinafter abbreviated as NBR). It provides low compression set to the body, does not require vulcanization, and can be extruded or injection molded, making it suitable for sealing materials, backing materials, and OA.
The present invention relates to a thermoplastic elastomer composition useful for equipment rolls, etc., and a method for producing the same.

[Prior art] Soft vinyl chloride resin, which is made by adding a plasticizer to vinyl chloride resin, has properties similar to so-called vulcanized rubber, and is also excellent in moldability, weather resistance, colorability, cost, etc. It is widely used as films, sheets, leather, etc. However, since the compression set is larger than that of vulcanized rubber, its use at high temperatures is limited, and it has the disadvantage that it is difficult to use for various roll materials, backing materials, sealing materials, and other applications.

To improve the compression set of vinyl chloride resin, there is a method of adding crosslinked NBR to crosslinked vinyl chloride resin (see JP-A-58-215442, JP-A-59-51933, and JP-B-63-44782). This is known, and the present applicant has filed an application for a composition that provides a low compression set by adding a silicone resin or crosslinked NBR to a vinyl chloride resin (Japanese Patent Application No. 1-254386).

(Japanese Patent Application No. 2-61106), a composition with low compression set using a crosslinked vinyl chloride resin cannot obtain a sufficiently low compression set unless the crosslinking rate is increased. The elevated composition had poor processability, making extrusion molding and injection molding difficult, and was not in a satisfactory state. Furthermore, regarding compositions in which silicone resin or partially crosslinked NBR is added to vinyl chloride resin, the lack of compatibility between vinyl chloride resin and silicone resin results in insufficient mechanical strength of both compositions. Compositions containing partially crosslinked NBR also lack mechanical strength, and therefore have the disadvantage that cracks tend to form in extruded products during extrusion molding.

[Problems to be Solved by the Present Invention] The present invention solves the above-mentioned problem of crack generation, provides a molded product with low compression set, does not require vulcanization, and can be extruded or injection molded. This was made to provide a resin-based thermoplastic elastomer composition.

[Means for Solving the Problems] The present inventor has developed a vinyl chloride resin that gives a molded article a low compression set and does not require vulcanization, based on a thermoplastic composition in which a plasticizer is added to a vinyl chloride resin. Studies have been conducted to obtain thermoplastic elastomer compositions based on the above-mentioned thermoplastic elastomer compositions. As a result, we found that a composition with the desired properties could be obtained by blending a silicone resin or a silicone resin and NBR with a vinyl chloride resin with a plasticizer added, as described above. However, it had the disadvantage that cracks were likely to form in the pressed clay molded product during extrusion molding. Therefore, we conducted extensive research to improve this drawback and confirmed that by adding methyl methacrylate resin, cracks would no longer occur and a molded product similar to general soft extrusion molding could be obtained without cracks. The present invention has been completed.

That is, the present invention uses vinyl chloride resin, plasticizer, silicone resin, methyl methacrylate resin, and NB
The gist of the present invention is a thermoplastic elastomer composition characterized by comprising R, and a method for producing the thermoplastic elastomer composition using an addition reaction type silicone resin described below.

The present invention will be explained in more detail below.

In the present invention, a known vinyl chloride polymer can be used as the vinyl chloride resin, and usually has a degree of polymerization of 3.
Polymers in the range of 00 to 10,000 are used, but it is also possible to use any polymer alone or in the range of 2 to 10,000.
More than one species can also be used together. This polymer consists of straight vinyl chloride, partially crosslinked vinyl chloride, and vinyl chloride.
Vinyl acetate copolymer, vinyl chloride-ethylene copolymer,
Copolymers mainly composed of vinyl chloride, such as vinyl chloride-ethylene-vinyl acetate copolymers, vinyl chloride-acrylic copolymers, and vinyl chloride-urethane copolymers, may also be used.

Known plasticizers can be used as the plasticizer,
This includes, for example, di-2-ethylhexyl phthalate (DO
P), dibutyl phthalate fDBP), dihebutyl phthalate (DHP), diisononyl phthalate (DINP)
Di-2-ethylhexyl adipate (DOAI) Diisononyl adipate (DINA), Diisodecyl adipate (DIDA), Trioctyl trimellitate (TOT)
M) Triisodecyl trimellitate (TITM), epoxidized soybean oil, epoxidized linseed oil, etc. can be mentioned, but 3 parts by weight per 100 parts by weight of the above vinyl chloride resin.
It may be added in an amount of 0 to 200 parts by weight, preferably 50 to 150 parts by weight.

Next, to explain the silicone resin used in the present invention, various types can be used.
Among them, 0.5% of all organic groups bonded to silicon atoms.
0.01 mole% or more of vinyl siloxane is a vinyl group and a hydrogen group has a molar ratio of 1:0.7 to 1:20 of hydrogen groups bonded to silicon atoms to the vinyl groups. Polymers are preferred. Furthermore, the following formula [1] % formula % [1] (where R is a group selected from a methyl group, an ethyl group, a vinyl group, a phenyl group, and an alkoxyl group, and a represents a number from 1 to 3. ), containing 0.01 mol% or more of vinyl siloxane units in all siloxane units, and a degree of polymerization of 300 to 8.000, preferably 1,000 to 5.0.
00 vinyl siloxane and the following formula [2] % formula % [2] (where R is a hydrogen group, a methyl group, an ethyl group, a vinyl group,
It is a group selected from a phenyl group and an alkoxyl group, and b represents a number from 1 to 3. ), and the hydrogen siloxane units are 5 to 20 mol% of the total siloxane units.
The degree of polymerization contained above is 5 to 1.000, preferably 50 to
It is more preferable to add-polymerize 500 organohydrodiene siloxane with a platinum-based catalyst, and the blending ratio of both is as described above in the molar ratio to the vinyl group bonded to the silicon atom in formula [1]. [2] The ratio of hydrogen groups bonded to silicon atoms in the formula is preferably 1:0.7 to 1:20, more preferably 1:1 to 1:15.Addition polymerization As for the platinum-based catalyst used for this purpose, platinum chloride is usually added as a 1 to 5% solution of isopropyl alcohol in an amount of 10 to 1.000 ppm, preferably 50 to 500 ppm, based on the vinyl siloxane.

In addition, two-component silicone rubber (LI
M material) and/or low temperature curing silicone rubber (abbreviated as LTV) may also be used.

Regarding the mixing ratio of silicone resin to vinyl chloride resin, if the amount of silicone resin blended is less than 1 part by weight with respect to 100 parts by weight of vinyl chloride resin, the improvement in compression set will not be expected, and if it is more than 60 parts by weight. Even if it is added, the compression set will not be improved any further (at the same time, it will become expensive, so the amount may be in the range of 1 to 60 parts by weight, but preferably in the range of 3 to 30 parts by weight).

Next, to explain the methyl methacrylate resin used in the present invention, a resin with a high degree of polymerization is suitable for this resin, and among these resins, those with a degree of polymerization of 10.000 to 300,000 are preferable.
Such methyl methacrylate resin is known as a gelling promoter for vinyl chloride and an impact resistance improver for hard vinyl chloride; They discovered that this method is effective in preventing cracks from forming during molding of thermoplastic elastomers. Commercially available products can be used in the present invention, such as Metabrane P-501, Metabrane P-550, Metabrane P-551, Metabrane P-530, Metabrane P-531, Metabrane L-1000 [all Mitsubishi Rayon ■ product name], Kane Ace PA-100, Kane Ace PA-20 [all product names manufactured by Kanekabuchi Chemical Co., Ltd.], and the like.

The amount of this methyl methacrylate resin to be blended with the vinyl chloride resin may be 0.5 to 30 parts by weight, preferably 1 to 100 parts by weight of the vinyl chloride resin.
~10 parts by weight. If it is less than 0.5 parts by weight, crack prevention will not be perfect, and if it exceeds 30 parts by weight, there will be no significant increase in effectiveness, and moreover, it will result in an increase in cost.

Next, NBR used in the present invention is preferably a cross-linked nitrile rubber containing a gel content that is insoluble in methyl ethyl ketone (hereinafter abbreviated as MEK), and in particular, the gel content is 20 to 95% by weight and the balance is MEK. A cross-linked type having a bonded acrylonitrile content of 20 to 45% by weight, consisting of a soluble component, is preferred and can be selected from commercially available products. By adding this cross-linked NBR, the compression set is significantly reduced and improved, and a synergistic effect is exhibited, compared to when a silicone resin is solely blended with a vinyl chloride resin.

The amount of NBR to be blended may be 10 to 200 parts by weight, preferably 50 to 120 parts by weight, per 100 parts by weight of the vinyl chloride resin. If 7 bars are less than 10 parts by weight, the effect of improving compression set will be small, and even if λ exceeds 200 parts by weight, no increase in the effect will be seen.

In addition to the above-mentioned essential components, non-liquid polymeric substances such as urethane, EVA, etc. are added to impart flexibility, and calcium stearate is added as a stabilizer to impart heat resistance and thermal stability. , addition of metal soaps such as magnesium stearate, zinc stearate, lead stearate, organic silicone stabilizers, ester stabilizers such as butyl stearate, foaming agents, conductivity imparting agents, surfactants, Addition of fungicides, magnetism imparting agents, organic or inorganic pigments, etc. is optional as long as it does not impair the purpose of the present invention.

The thermoplastic elastomer composition of the present invention can be granulated and molded by the same process as conventional vinyl chloride resins. That is, a plasticizer is added to and absorbed into a vinyl chloride resin using a mixer such as a super mixer, a blender, or a Henschel mixer, and then a stabilizer and the like are mixed in to obtain a powdered soft vinyl chloride resin. Next, after winding this soft vinyl chloride resin around a heated roll, a silicone resin is added, or the powdered soft vinyl chloride resin is kneaded for 1 to 5 minutes in a heated pressure kneader or Banbury mixer. After making it into a lump, silicone resin and NBR may be added to it and mixed. Alternatively, a vinyl chloride resin, a plasticizer, and a silicone rubber compound may be added and kneaded at once using a coaxial or twin-screw extruder.

A better method is to use an addition reaction type silicone resin (for example, vinyl siloxane represented by the formula [1] above and [2
[Hydrodiene siloxane combination shown by the formula or L I M material, etc.], the vinyl siloxane and platinum catalyst, which are components of this addition reaction type silicone resin, are combined with the vinyl chloride resin, a plasticizer, and methyl methacrylate. Separately, hydrogen siloxane, which is the remaining component of the addition reaction type dinocone resin, is mixed with vinyl chloride resin, plasticizer, and methyl methacrylate resin to form other components. This is a method of preparing the composition of the present invention by mixing both components and partially crosslinked NBR. This method was invented by the present inventor, and according to this method, a composition with more excellent properties can be easily obtained.

This will be further explained as follows assuming that the siloxanes represented by formulas [1] and [2] are used. First, a vinyl chloride resin, a plasticizer, a vinyl siloxane represented by the formula [1F], a platinum catalyst (50 to 1 OOOPPM per vinyl siloxane), and a methyl methacrylate resin are heated to an elevated temperature using a Henschel mixer, a super mixer, etc. While mixing, the plasticizer is absorbed into the vinyl chloride resin (a method commonly referred to as dry-up). The resulting mixture is abbreviated as a composition. On the other hand, a vinyl chloride resin, a plasticizer, a hydrogen siloxane represented by formula [2], and a methyl methacrylate resin are dried up in the same manner as described above. The resulting mixture is abbreviated as composition (2). Next, partially crosslinked NBR is added to both components of the obtained composition W and composition H, and then kneaded using a Banbury mixer 1 extruder, two heated rolls, etc., and pelletized using a pelletizer, hot cut, etc.

The obtained pellets can be easily processed by various molding methods such as extrusion molding, injection molding, press molding, etc. in the same operation as ordinary soft vinyl chloride or thermoplastic rubber, and do not crack during processing. Reuse (recycling) is also possible.

Of course, as mentioned above, it is optional to add components other than the essential components as necessary as long as it does not impair the purpose of the present invention. For example, if you want to obtain a foam, it is also possible to add a foaming agent to cause foaming. It is.

[Example] Specific aspects of the present invention will be described below with reference to Examples, but the present invention is not limited thereto. In addition, parts in the examples indicate parts by weight, and the compression set is 70
℃, measured values after 22 hours.

Example 1 130°C using a Henschel mixer with the following formulation.
Composition A was obtained.

Vinyl chloride resin (average degree of polymerization 2,500) 1
00 parts DOP (Plasticizer) 100 parts Ba-Zn stabilizer No. 6519 [Product name manufactured by Akishima Chemical Industry Co., Ltd.] 2.0 parts Ba-Zn stabilizer No. 3053 [Product name manufactured by Akishima Chemical Industry ■ Part name 10. 6 parts polymethyl methacrylate (degree of polymerization 200.ODD) 3.0 parts dimethylmethylvinyldiphenylpolysiloxane (methylvinylsiloxane unit 0.5 mol%).

5 mol% diphenylsiloxane units.

Viscosity at 25°C: 5.000 Bois) 20 parts 2% isopropanol solution of chloroplatinic acid 01 parts Apart from the above,
130℃ using a Henschel mixer with the following formulation.
Composition B was obtained.

Vinyl chloride resin (average degree of polymerization 2,500) 1
00 parts DOP (plasticizer) 100 parts Ba-Zn stabilizer No. 6519 (mentioned above) 2,
0 parts Ba-Zn stabilizer No. 3053 (mentioned above)
0.6 parts polymethyl methacrylate (degree of polymerization 200,000) 3.0 parts dimethylmethylhydrodiene diphenylpolysiloxane (5 mol% methylhydrodiene siloxane units, 5 mol% diphenylsiloxane units, viscosity at 25°C 300 centistokes) 30 parts Next, composition A
225.7 parts, 8208.6 parts of the composition, and partially crosslinked NBR as PNC38 [product name manufactured by Nippon Synthetic Rubber ■] 2
Composition C was obtained by uniformly mixing and dispersing the mixture at room temperature for 10 minutes using a Henschel mixer.

The obtained composition C was extruded using a twin-screw extruder with a diameter of 50 mm at a die temperature of 150° C., and a pellet was obtained by hot cutting.

From the obtained pellet, L/D with a screw diameter of 30 mm
Using an extruder with = 22 and compression ratio = 3.5, a square string with a thickness of 1 mm and a width of 30 mm was extrusion molded under the conditions of a screw rotation speed of 30 rpLo and a die temperature of 170°C. Extrusion molding was easy, no cracks occurred, and continuous molding was possible. The obtained molded article showed no difference in appearance or other aspects from ordinary soft vinyl chloride molded articles, and could be fully used as a product.

Comparative Example 1 Compositions A and B of Example 1 were the same as Example 1 except that the methyl methacrylate resin was removed from each formulation.
Composition A' and Composition B' were prepared in the same manner as above. Then, 222.7 parts of composition A', 205 parts of composition B'
．． 6 parts and 200 parts of PNC3B (above) as partially crosslinked NBR were uniformly mixed and dispersed for 10 minutes at room temperature using a Henschel mixer to obtain composition C'. The resulting composition C' was pelletized using the same extruder as in Example 1, and the pellets were extruded using the same extruder as in Example 1 under the same conditions, but cracks occurred in the molded product during extrusion. , commercialization was difficult and impractical.

Example 2 The pellet of composition C obtained in the example process was heated to 160 to 165°C.
After preforming by sheeting with two 6-inch rolls, a sheet was obtained by press molding at 170° C. for 5 minutes. A test piece was prepared from this sheet, compressed by 25% of the thickness in accordance with JIS K 6301, and left at 70°C for 22 hours, after which the compression set was measured. The results showed a value of 36%.

Comparative Example 2 Composition A'' and Composition B' were prepared in the same manner as in Example 1, except that the silicone resin was removed from each formulation of Compositions A and B of Example 1. 205.7 parts of Composition A, 6 parts of Composition B, and 100 parts of PNC38 (mentioned above) as a partially crosslinked NBR per 1 part of vinyl chloride resin were similarly blended to form Composition C. This was pelletized in the same manner as in Example 2, and a sheet was made in the same manner as in Example 2. The compression set was measured and found to be 45%.

[Effect of the invention] A thermoplastic elastomer composition composed of a vinyl chloride resin, a plasticizer, a silicone resin, and acrylonitrile-butadiene rubber (NBR) has a characteristic of having a small compression set. The disadvantage is that molded products are prone to cracking.

The present inventor has discovered that the above-mentioned drawbacks can be improved by adding methyl methacrylate resin to this thermoplastic elastomer composition, and as a result, a vinyl chloride thermoplastic elastomer with low compression set can be produced. Therefore, the effects of the present invention are extremely large.

Claims (1)

[Scope of Claims] 1. A thermoplastic elastomer composition comprising a vinyl chloride resin, a plasticizer, a silicone resin, a methyl methacrylate resin, and an acrylonitrile-butadiene rubber. 2. When producing a thermoplastic elastomer composition characterized by comprising a vinyl chloride resin, a plasticizer, a silicone resin, a methyl methacrylate resin, and an acrylonitrile-butadiene rubber, a vinyl siloxane and a platinum addition catalyst are used. It is mixed with vinyl chloride resin, plasticizer, and methyl methacrylate resin to form one component, and separately, hydrogen siloxane is mixed with vinyl chloride resin, plasticizer, and methyl methacrylate resin to form another component, and then A method for producing the thermoplastic elastomer composition, which comprises mixing both of the above components and an acrylonitrile-butadiene rubber.