JP3288530B2 - Thermoplastic elastomer composition and use thereof - 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 obtained by dynamically vulcanizing a specific thermoplastic polystyrene-based elastomer and rubber, and its use, and in particular, to a low resilience having high energy absorption performance. The present invention relates to a thermoplastic elastomer composition which has a low compression set and is excellent in moldability.

[0002]

2. Description of the Related Art For example, an acoustic device such as a CD player is provided with a vibration damping material in order to prevent external vibrations from being transmitted to the main body of the device.
This vibration isolator is required to have high energy absorption performance, that is, low rebound resilience. In order to satisfy this demand, conventionally, a rubber composition using a rubber composition containing polynorbornene or butyl rubber as a main component, an ultra-hard composition containing urethane or butyl rubber as a main component, and a PVC containing a main component Elastomer compositions have been used as materials for vibration damping rubber.

However, when the above materials are used as the vibration damping material, a vulcanization step is indispensable in order to improve the physical properties of the material. Since the vulcanized rubber molded product has burrs in the molding process, a deburring process is required, and there is a problem that productivity is poor. On the other hand, since the material is thermoplastic, injection molding is possible, and since there is no burr in the molded product, there is an advantage that a deburring step is unnecessary, but since it does not have a crosslinked structure, particularly, There is a problem that the compression set at a high temperature (for example, 70 ° C.) becomes large.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a thermoplastic elastomer composition having high energy absorption performance, a low compression set, and excellent moldability, and its use. is there.

[0005]

Means for Solving the Problems The present invention has been proposed to achieve the above-mentioned object, and has the following constitution. The thermoplastic elastomer composition according to claim 1, wherein polyisoprene having a polystyrene in a hard segment and a vinyl structure in a soft segment is water-containing.
It is characterized by dynamically cross-linking 20 to 80% by weight of a triblock copolymer having an additive and 80 to 20% by weight of a rubber.

Further, in the thermoplastic elastomer composition according to the present invention, a part of the triblock copolymer is a hydrogenated product of styrene-isoprene-styrene, styrene-butadiene-styrene, styrene-isoprene-styrene, and styrene-isobutylene. It is characterized by being substituted by at least one elastomer selected from the group consisting of hydrogenated butadiene-styrene.

According to a third aspect of the present invention, there is provided a vibration isolator for a weak electric device, comprising the thermoplastic elastomer composition according to the first or second aspect. . The stopper for an opening / closing member according to claim 4, wherein the opening / closing member is provided so as to reciprocate between an opening position for opening a predetermined space and a closing position for closing the space. 2. A stopper for an opening / closing member interposed between a wall portion located near a position and a shock between the opening / closing member moving from the closed position to the open position and the wall portion, the stopper being provided between the wall portion and the opening / closing member. Or the thermoplastic elastomer composition described in 2 above.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The most important technical features of the present invention are:
The object is to dynamically crosslink a rubber by melt-kneading a specific thermoplastic elastomer and a rubber. Thereby, the obtained thermoplastic elastomer is not crosslinked,
Only the rubber is in a crosslinked state, and the rubber particles are finely dispersed in the composition. As a result, the molecular rotation hindrance of the soft segment constituting the thermoplastic elastomer increases, and the loss coefficient increases. That is, it has the characteristic that the rebound resilience is low.

Further, as described above, since the dynamically crosslinked rubber is finely dispersed in the composition, the compression set can be suppressed to a small value and the solvent resistance and the solvent resistance can be reduced as compared with the case where the thermoplastic elastomer is used alone. The heat softening temperature can also be improved. Further, the obtained composition shows thermoplasticity because the thermoplastic elastomer is not crosslinked. Therefore, molding can be performed by ordinary resin injection or the like, and burrs are not generated on the molded product, so that secondary processing such as deburring becomes unnecessary.

The thermoplastic elastomer used in the present invention has polystyrene in the hard segment and hydrogenates polyisoprene having a vinyl structure in the soft segment .
Triblock copolymer having a thing (hereinafter, vinyl S
It is referred to as an IS block copolymer. ). in this case,
Polyisoprene may be cis or trans.

The vinyl SIS block copolymer has a styrene content of hardness, MFR (melt flow rate).
In view of this, the content is preferably 5 to 50% by weight, particularly 10 to 35% by weight. As such a vinyl SIS block copolymer, trade names “VS-1” and “VS-
3 "," HVS-1], "HVS-3" ( all
Kuraray) can be used. In using the vinyl SIS block copolymer, the vinyl SIS block of the present invention is used.
Hydrogenated rock copolymer soft segment
The feature is that heat resistance and weather resistance are particularly enhanced .

Incidentally, a part of the vinyl SIS block copolymer is replaced with SIS (styrene-isoprene-styrene),
SBS (styrene-butadiene-styrene), SEPS
(Hydrogenated SIS) and SEBS (hydrogenated SBS). In addition, in view of the compatibility with the soft segment, the rubber which is a part of the material forming the thermoplastic elastomer composition of the present invention has a rubber dissolution parameter value (SP value) of 7.85 to 8.13. Are preferred. Rubber having an SP value in this range is described in, for example, "Rubber Industry Handbook" published by the Japan Rubber Association and "Introduction to New Rubber Technology" published by the Association, and IIR, Although all rubbers such as hydrogenated polybutadiene and cis IR can be used, it is preferable to use IIR (SP value 7.85) in terms of loss factor.

In the composition of the present invention, the mixing ratio of the vinyl SIS block copolymer is 20 to 80% by weight,
Preferably, it is 40 to 70% by weight, and the compounding ratio of the rubber is 80 to 20% by weight, preferably 60 to 30% by weight. The reason for such a mixing ratio is that
The mixing ratio of the vinyl SIS block copolymer component is 80
If the content is more than 10% by weight, reduction of compression set of the obtained composition, imparting of flexibility to the composition, and lowering of hardness are not sufficiently recognized, and the mixing ratio of the vinyl SIS block copolymer is 20%. If the amount is less than 10% by weight, the moldability and thermoplasticity of the resulting composition will be insufficient, causing a decrease in MFR and inferior moldability by injection.
Also, dimensional stability due to increase and shrinkage of surface roughness is inferior.

In the present invention, as described above, rubber is
It is characterized by dynamically crosslinked points. In the present invention, the term “dynamic crosslinking” refers to W.C. M. Fischer and A. Y. Cor
A method developed by An et al., which refers to a process in which rubber is highly crosslinked in a thermoplastic resin matrix and the rubber is finely dispersed.

As the crosslinking agent used in the dynamic crosslinking, peroxides, resin crosslinking agents, sulfur and the like used for ordinary rubbers can be used, and specific examples thereof are a crosslinking agent handbook (published by Taiseisha). And crosslinking assistants such as metal oxides and thiuram-based crosslinking accelerators described in the above. As an example, when a sulfur-based crosslinking agent is used, based on 100 parts by weight of the rubber in the composition,
0.1 to 8 parts by weight of a crosslinking agent, 0.1 to 10 parts by weight of a crosslinking accelerator, 0.5 to 10 parts by weight of a crosslinking aid, 0.5 to 10 parts by weight of an activator, 0.1 to 10 parts by weight of a crosslinking aid 1
It can be used in the range of 0 parts by weight.

A softener may be added to the composition of the present invention for the purpose of improving flexibility (low hardness) and fluidity. As the softener, those usually used for rubbers and the like can be used, but preferably, paraffin-based,
A petroleum-based softening agent such as a naphthene-based softening agent or a mixture thereof is used.
It is determined within this range depending on the required hardness.

Further, fillers and reinforcing agents generally used for rubbers and thermoplastic elastomers, such as carbon black, silica and calcium carbonate, are added to the composition of the present invention within a range that does not affect the physical properties. It is also possible. The dynamic crosslinking in the present invention is carried out by kneading the above components using various extruders, Banbury mixers, kneaders, or a combination thereof, and in particular, a twin-screw kneading extruder Good to use. As the twin-screw kneading machine, L / D = 15 or more,
In particular, it is preferable to use 30 or more. The method of adding each component includes a method of simultaneously adding a filler, a plasticizer, and a cross-linking agent to both components of the vinyl SIS block copolymer and rubber, a method of adding both components of the vinyl SIS block copolymer and rubber, a filler, and a plasticizer. After kneading, a method of adding a crosslinking agent may be used.

The rubber of the present invention is, as described above, a vinyl SI
The rubber is preferably dispersed and mixed in the S block copolymer, and the average particle diameter of the rubber in the dispersed state is 50%.
μm or less is preferred. If the dispersed particle size of the rubber is larger than 50 μm, the elasticity and thermoplasticity are poor, and the compression set (C
This is because physical properties such as S) cannot be sufficiently obtained. Also,
A compatibilizer may be used to sufficiently disperse the rubber in the vinyl SIS block copolymer and strengthen the interface to improve physical properties and moldability. Specific examples of the compatibilizer are:
For example, it is described in “Polymer Processing”, Vol. 40, No. 4, 1991, etc., and it is roughly divided into those having no chemical reaction and those having a chemical reaction, and both can be used.

The former is usually a block copolymer or a graft copolymer and exhibits a so-called emulsifying action. The latter is a polymer having a functional group at a terminal or a side chain, a polymer macromer having a polymerizable group at a terminal of the polymer, or the like. In the present invention, a glycidyl group at the terminal, or
It is preferable to use a compatibilizer having a carboxyl group from the viewpoint of improving physical properties and moldability. Specific examples include Tuftec M1943 and M191 manufactured by Asahi Kasei Corporation.
1, M1913 (trade name) and the like. The thermoplastic elastomer composition formed as described above has high energy absorption performance and can suppress the compression set to a small level, so that it can be suitably used as a vibration damping material for absorbing vibration of a weak electric device. Here, the weak electrical device mainly means an electrical device that operates at a relatively low current, such as an audio device, an information device, a video device, and a video device, and specifically includes a CD, MO, MD, and CD. -ROM, HDD, etc. can be exemplified.

Further, the thermoplastic elastomer composition according to the present invention can be suitably used as a stopper for an opening / closing member. In the present invention, the opening / closing member is a house,
It means a member for forming a luggage compartment, which is a door for a car, a cargo in a truck, and the like. The opening and closing member is provided so as to be able to reciprocate between an open position for opening a predetermined space such as a room in a house or a luggage room of a truck and a closed position for closing the space. Further, a wall portion (wall portion forming a room of a house, a truck body, or the like) located near the open position, or a portion corresponding to the wall portion of a door for a house (a luggage room of a truck is formed). A member corresponding to the wall)
Is provided with an opening / closing stopper formed of the thermoplastic elastomer composition according to the present invention. Thereby, even when the opening / closing member is moved from the closed position to the opening position in order to make the predetermined space open, the impact between the opening / closing member and the wall is sufficiently absorbed by the opening / closing member stopper. The danger due to the rebound of the opening / closing member is prevented.

Further, the thermoplastic elastomer composition according to the present invention may be provided on an outer surface of a side wall of a ship. This allows
As the ship approaches the pier, the thermoplastic elastomer composition functions to prevent shock and breakage when the side wall of the ship collides with the quay. Further, the thermoplastic elastomer composition according to the present invention is also suitable as a stopper for preventing a train or an automobile from directly hitting the garage when the train or the automobile is put in the garage.

The use of the present invention will be described below with reference to the embodiments shown in FIGS. FIG. 1 shows a mounting structure of a CD player according to the present invention, in which a thermoplastic elastomer composition according to the present invention is used for a damper 18. That is, the CD player main body 10 is elastically supported by the upper plate 14 of the CD player case 12 by the spring 16. A damper 18 is provided between the CD player main body 10 and the CD player case 12. As described above, the main body of the damper 18 is formed of the thermoplastic elastomer composition according to the present invention, and the viscous fluid 20 is sealed in the main body. The center of the bottom of the damper 18 is a stirrer 19 protruding toward the interior of the viscous fluid 20, and a stirrer shaft 22 protruding from the CD player body 10 is inserted into a recess 19 </ b> A of the stirrer 19. The vibration is attenuated by viscous resistance when the stirring section 19 stirs the viscous fluid 20 integrally with the stirring shaft 22. In the present embodiment, as described above, the damper 18 is formed of the thermoplastic elastomer composition according to the present invention, so that the vibration absorbing performance is high and the compression set can be reduced. Can be fully demonstrated.

In the above description, the thermoplastic elastomer composition according to the present invention is used for the damper 18 for supporting the CD player main body 10. However, in the CD player, the thermoplastic elastomer composition is used for the clamper for holding the disc by the turntable. May be. Thus, the clamper can sufficiently absorb the vibration of the disk during driving of the disk.

Further, the thermoplastic elastomer composition according to the present invention can be used for a strut coil type suspension used for front and rear wheels of a passenger car. That is, this suspension is a suspension in which a spring 26 is combined with a strut assembly 24 shown in FIG. 2 in which a hydraulic shock absorber is incorporated in an outer cylinder integrated with an axle (not shown). The thermoplastic elastomer composition according to the present invention is used for the bump rubber 28, whereby the bump rubber 28 can sufficiently exhibit a function as a stopper for suppressing displacement when an excessive load is applied to the wheel. ing.

Further, the application of the thermoplastic elastomer composition according to the present invention is not limited to the suspension of the type shown in FIG. 2, but can be used for various stopper front suspensions. Can be sufficiently absorbed. The stopper is used after being formed into various shapes as shown in FIGS. 3A to 3H in consideration of a portion to be used, vibration absorption characteristics, and the like. In particular, FIG. 3G is suitably used as a door stopper.

Further, the thermoplastic elastomer composition according to the present invention can be used for a stopper / rear suspension of a passenger car, and can sufficiently exhibit a performance of absorbing vibration from a road surface. This stopper is used after being formed into various shapes shown in FIGS. 4A to 4E in consideration of a portion to be used, vibration absorbing characteristics, and the like.

FIG. 5 shows a leaf spring 30 for a truck.
Is shown, and the thermoplastic elastomer composition according to the present invention is used for the bump rubber 32. The leaf springs 30 are provided so that the steering stability can be achieved even when the load of the truck is slightly changed or the balance between the front, rear, left and right loads is changed.
5, the bump rubber 3 formed by the thermoplastic elastomer composition according to the present invention as described above.
2 are provided, and the bumper bar 32
The deflection of the leaf spring 30 is suppressed.
As described above, the thermoplastic elastomer composition according to the present invention has a high impact vibration absorbing performance, and thus exhibits a sufficient function as the bump rubber 32.

[0028]

The present invention will be specifically described below with reference to examples. < Example 1 > Of the rubber compounds shown in Table 1, those excluding sulfur and the crosslinking accelerator TT were kneaded with a roll. Thereby, the obtained compound and HVS-3 (trade name) manufactured by Kuraray Co., Ltd. as a thermoplastic elastomer were mixed at a weight ratio of 5: 5, and the mixture was rotated with a screw using a twin-screw kneading extruder. The mixture was kneaded at a number of 260 rpm and a kneading temperature of 200 ° C., and sulfur and a crosslinking accelerator TT were added from the middle of the kneading process, and kneaded to perform dynamic crosslinking. The resulting mixture was pelletized, and a test sample was formed at 210 ° C., 200 ° C., 190 ° C., and 180 ° C. with an injection molding machine at a cylinder temperature of 210 ° C., 200 ° C., 190 ° C., and 180 ° C. Table 2 shows the physical results of the test items and the test results.
It was shown to.

< Comparative Example 1 > A physical test was conducted on HVS-3 (trade name) manufactured by Kuraray Co., Ltd., which is a thermoplastic elastomer, and the test results are shown in Table 2.

[0030]

[0031]

[0032] In Table 2, E _B is the elongation (%), T
The _B Tensile strength ^{(Kgf / cm 2), T} R is the tear strength (Kgf / c
m), CS is compression set (%), H _S is JIS A, R _B is impact resilience (%), immersed rate when using tan [delta] is the loss tangent, methyl ethyl ketone Delta] m ₁₀₀ As the solvent (%) And these tests were performed in accordance with JIS K 6301. However, the measurement of tan δ is performed by a dynamic viscoelasticity measurement system using a non-resonant forced vibration method, specifically, D
Using a DV-25FP (manufactured by Orientec Co., Ltd.), both ends of the test sample in the longitudinal direction were fixed and measured. In this measurement, the test sample has a width of 5.0 m.
m, a thickness of 2.0 mm, and a length of 30.0 mm (however, this length is the length of the part excluding both ends held by the jig). 5H
z, the temperature was 0 ° C. The CS was measured at a heat treatment temperature of 25 ° C. and a treatment time of 22 hr.

[0033]

According to the present invention, a thermoplastic elastomer composition having a high energy absorption performance, a small compression set, and excellent moldability can be provided. As a suitable use thereof, it is possible to provide a molded article such as a vibration isolator for a weak electric device and a stopper for an opening / closing member.

[Brief description of the drawings]

FIG. 1 shows a thermoplastic elastomer composition according to the present invention
It is sectional drawing which shows the Example at the time of using for the damper of D player.

FIG. 2 is a schematic structural view showing an example in which the thermoplastic elastomer composition according to the present invention is applied to a strut coil type suspension used for a front wheel of a passenger car.

3 (A) to 3 (H) are perspective views showing the shapes of a stopper front suspension or a door stopper using the thermoplastic elastomer composition according to the present invention.

4 (A) to 4 (E) show stoppers, rears, and stoppers using the thermoplastic elastomer composition according to the present invention.
It is a perspective view which shows the shape of a suspension.

FIG. 5 shows a thermoplastic elastomer composition according to the present invention,
It is a figure showing the case where it is used for a bumper bar of a leaf spring for trucks.

[Explanation of symbols]

 18 Damper 28 Bumper bar 32 Bumper bar

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 53/02 C08J 3/24 CEQ C08L 21/00

Claims (4)

(57) [Claims] 1. A hard segment containing polystyrene and a soft segment containing polyisoprene having a vinyl structure.
Triblock copolymer having hydrogenated version 20
To 80% by weight and 80 to 20% of rubber by dynamic vulcanization. 2. A part of the thermoplastic elastomer composition according to claim 1, wherein the styrene-isoprene-styrene, styrene-butadiene-styrene, styrene-isoprene-
2. The thermoplastic elastomer composition according to claim 1, wherein the thermoplastic elastomer composition is substituted by at least one elastomer selected from the group consisting of hydrogenated styrene and hydrogenated styrene-butadiene-styrene. 3. A vibration damping material for a weak electric device, comprising the thermoplastic elastomer composition according to claim 1. 4. An opening / closing member provided to be able to reciprocate between an open position for opening a predetermined space and a closed position for closing the space, and a wall located near the open position. And a stopper for the opening / closing member to be brought into contact with the opening / closing member, which is interposed between and moves from the closed position to the open position, wherein the stopper is made of the thermoplastic elastomer composition according to claim 1 or 2. Features a stopper for opening and closing members.