JPH10298352A - Elastomer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an elastomer capable of simultaneously showing an excellent flexibility, excellent impact absorbability and excellent elastic recovery and useful for vehicle seats, handle grips, soles, etc., by adding plural kinds of plasticizers to a thermoplastic elastomer. SOLUTION: This elastomer contains (A) a thermoplastic elastomer comprising a hard segment (Hs) and a soft segment (Ss) (e.g. a polystyrene-based thermoplastic elastomer) as a main component. Therein, (B) two kinds of plasticizers are added to the component A. The elastomer is obtained e.g. by adding a plasticizer capable of plasticizing the component Hs and a plasticizer capable of plasticizing the component Ss as the component B to the component A. Thereby, the values of storage elasticity and loss tangent can suitably be adjusted to express the objective various performances.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is applicable as a cushion material used for furniture, bedding and the like, and in particular, a vehicle seat for automobiles and motorcycles, a cushion material such as a handle and a handle grip, a shoe sole and the like. More particularly, the present invention relates to an elastic body having a small storage elastic modulus and a large loss tangent (tan δ), that is, a flexible elastic body having a large shock absorbing power.

[0002]

2. Description of the Related Art Elastic bodies have been used in a wide range of fields because of their excellent properties such as vibration-proofing and heat-insulating properties. Conventionally, a crosslinked rubber has been mainly used as an elastic body, but recently, a thermoplastic elastomer has been used in addition to a thermosetting resin such as polyurethane. Thermosetting resins such as polyurethanes have the advantage of easily improving properties, but require irreversible heat-curing reactions, which limits the shortening of molding cycles and makes it difficult to stabilize quality. There is a problem that it is difficult to recycle.

[0003] On the other hand, thermoplastic elastomers exhibit rubber elasticity by physically constraining the molecular motion of soft segments by hard segments, and a wide variety of thermoplastic elastomers are commercially available. This thermoplastic elastomer has an advantage that the molding cycle is short, an injection molding method that can easily form a complicated shape can be adopted, and the quality of the obtained product is stable. Further, cross-linked rubber and thermosetting resin have an advantage that recycling is difficult, which is difficult. Therefore, demand has recently been growing.

[0004] However, various thermoplastic elastomers currently on the market are often inferior in elasticity and flexibility because of their emphasis on strength. For example, when used in cushioning materials such as vehicle seats and handle grips that make the user feel soft when in contact with the human body, they have low repulsion, have elastic recovery to absorb shocks, and have flexibility. However, it is difficult to obtain such an elastic body using only the thermoplastic elastomer. Therefore, it is conceivable to add a plasticizer. However, depending on the amount of the plasticizer, the hard segment cannot restrain the soft segment and does not exhibit elasticity. Cannot obtain the desired elastic body.

[0005]

SUMMARY OF THE INVENTION Accordingly, the object of the present invention is to provide an elastic body which is excellent in flexibility and excellent in shock absorption and elastic recovery on the premise of using a thermoplastic elastomer. Was.

[0006]

The elastic body of the present invention is an elastic body mainly composed of a thermoplastic elastomer composed of a hard segment and a soft segment, and two or more plasticizers are added to the thermoplastic elastomer. It has the greatest features where it is blended. As described above, it is difficult to obtain an elastic body having both flexibility, shock absorbing power and elastic recovery power by blending one kind of plasticizer into a thermoplastic elastomer, but two or more kinds of plasticizers are used in combination. This can solve this problem.
In particular, the first that can plasticize the hard segment
A plasticizer and a second plasticizer capable of plasticizing the soft segment are blended with the thermoplastic elastomer,
By adjusting the values of storage modulus and loss tangent to appropriate ranges,
A high-performance elastic body having both flexibility, shock absorbing power and elastic recovery power can be obtained.

The type of the thermoplastic elastomer is not particularly limited, but a polystyrene-based thermoplastic elastomer is preferably used because it is inexpensive, has good processability, and can provide an elastic body having excellent flexibility. Further, the use of the fine hollow particles has the effect of simultaneously reducing the weight and cost, and also has the effect of improving fuel efficiency by being used as seats for motorcycles and passenger cars and other shock absorbing materials.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, it is assumed that a thermoplastic elastomer is used, and in order to provide an elastic body which is excellent in flexibility and excellent in shock absorption and elastic recovery,
It has the greatest feature when more than one kind of plasticizer is used.

[0009] The thermoplastic elastomer has a hard segment and a soft segment, and exerts rubber elasticity at room temperature by locally constraining the molecular motion of the soft segment by the hard segment, and causes plastic deformation due to a rise in temperature. Therefore, processing is easy. There are various types of existence of the hard segment and the soft segment, such as those connected as one molecule like a block copolymer, those simply blended (mixed) like a polymer alloy, and those due to the difference in crystallinity. Regarding the type of restraint, there are a wide variety of thermoplastic elastomers such as a frozen phase, a hydrogen bond, a crystalline phase, an ionic crosslink, and a covalent crosslink.

As the thermoplastic elastomer preferably used in the present invention, polystyrene is a hard segment, a rubber component such as polybutadiene, polyisoprene, hydrogenated polybutadiene, hydrogenated polyisoprene, or a polyolefin such as ethylene-propylene rubber (EPM). Polystyrene-based elastomer with a soft segment as the system component; ethylene-propylene-diene copolymer (EP
DM), ethylene-propylene rubber (EPM), ethylene-butadiene rubber (EBM), butyl rubber (II
R), styrene-butadiene rubber (SBR), polyolefin elastomer having ethylene-vinyl acetate as a soft segment; crystalline polyvinyl chloride as a hard segment, and amorphous polyvinyl chloride or acrylonitrile-butadiene rubber (NBR) as a soft segment. Polyvinyl chloride-based elastomers; fluorine-based elastomers having a fluororesin as a hard segment and a fluororubber as a soft segment have excellent flexibility and can be preferably used.

A polyurethane elastomer having a urethane structure portion as a hard segment and a polyether or polyester as a soft segment; a polyester elastomer having a hard segment as a highly crystalline polyester and a soft segment as an amorphous polyether or an amorphous polyester. Elastomer; polyamide hard segment,
In the case of a polyamide-based elastomer having a soft segment of polyester or polyether, a flexible grade may be selected. Furthermore, for example, as in “Cosmogel” (Cosmo Keiki; polystyrene),
In the case of a thermoplastic elastomer emphasizing flexibility, it can be used alone or in combination with various thermoplastic elastomers exemplified above. The above thermoplastic elastomers may be used alone or as a mixture of two or more as long as they have good compatibility and do not adversely affect the elasticity or the like.

In the present invention, it is essential that two or more plasticizers are used in combination with the thermoplastic elastomer. If only one plasticizer is used for the thermoplastic elastomer,
This plasticizer selectively plasticizes the polymer with a higher affinity, either the hard segment or the soft segment, and as a result, it is not possible to obtain both flexibility and impact absorption / elastic recovery. It is.

By using two or more plasticizers, both the hard segment and the soft segment are appropriately plasticized. Many commercially available thermoplastic elastomers are designed with a polymer to increase the rebound resilience, but the properties of the thermoplastic elastomer can be easily changed by using two or more plasticizers in combination. In addition, it is possible to obtain an elastic body which is flexible and has a shock absorbing power and an appropriate elastic recovery power as the object of the present invention.
For example, if only the hard segments are plasticized, the soft segments do not exhibit the soft segment restraining effect, but are plastically deformed at room temperature and are no longer elastic. Also, when only the soft segment is plasticized, the hard segment, which is the constrained phase, is not plasticized. Thus, it is difficult to obtain an elastic body having excellent shock absorbing power and elastic recovery power. From this viewpoint, it is preferable that the plasticizer uses a first plasticizer capable of plasticizing the hard segment and a second plasticizer capable of plasticizing the soft segment. By plasticizing both the hard segment and the soft segment, it is possible to give flexibility to the entire elastomer while maintaining a good balance between the binding force of the hard segment and the rubber-like molecular motion of the soft segment. In addition, if the compatibility between the thermoplastic elastomer and the plasticizer or between the plasticizers is good, the
More than one species may be used.

The standard of the degree of plasticization is, for example, that the storage elastic modulus is 0.01 to 100 in dynamic viscoelasticity measurement at a constant temperature of 25 ° C. and a frequency of 0.1 to 100 Hz.
0.5 MPa, loss tangent (tan δ) is 0.2 to 1.0
It is preferable to perform so that By plasticizing the thermoplastic elastomer by appropriately setting the type and amount of the plasticizer so as to fall within this range, it is possible to obtain an elastic body having excellent flexibility and excellent shock absorbing power and elastic recovery power. Can be.

The types of the plasticizer include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), diheptyl phthalate (DHP), di (2-ethylhexyl) phthalate (DOP), Di (n-octyl) phthalate (N-DOP), diisodecyl phthalate (DIDP), diisononyl phthalate (DIN
P), butyl benzyl phthalate (BBP), butyl phthalyl butyl glycol (BPBG) and other phthalic acid esters; di (2-ethylhexyl) adipate (DO
A), di (2-ethylhexyl) azelate (DO
Aliphatic dibasic acid esters such as Z); tributyl phosphate (TBP), triphenyl phosphate (TPP), tricresyl phosphate (TCP), and trixylylenyl phosphate (TX)
Phosphoric esters such as P);
Ethylhexyl) (TOTM); other polyester plasticizers, epoxy plasticizers, aliphatic monobasic acid esters, dihydric alcohol esters, oxyacid esters,
General-purpose plasticizers such as chlorinated paraffins and process oils (saturated or inert petroleum unsaturated hydrocarbons) can be used.

The first plasticizer capable of plasticizing the hard segment and the second plasticizer capable of plasticizing the soft segment are selected from the group consisting of a hard segment and a soft segment in the thermoplastic elastomer. It is selected in consideration of solubility, plasticization efficiency, and the like. That is, the plasticizer exemplified above can be used as a first plasticizer for plasticizing a hard segment in a certain thermoplastic elastomer, while a second plasticizer for plasticizing a soft segment in another thermoplastic elastomer.
It can be used as a plasticizer and can be appropriately combined depending on the thermoplastic elastomer.

The object of the present invention is to provide an elastic body having both shock absorption and elastic recovery power and flexibility which can be used for cushioning materials and shoe soles. But polystyrene is hard segment, polybutadiene, polyisoprene,
Rubber components such as hydrogenated polybutadiene and hydrogenated polyisoprene, or ethylene propylene rubber (EPM)
A polystyrene-based thermoplastic elastomer having a polyolefin-based component such as a soft segment as a soft segment is preferable. Commercially available polystyrene-based thermoplastic elastomers include:
There are "Septon", "Hibler" (manufactured by Kuraray) and "Actimer" (manufactured by Riken Vinyl Industry).

The polystyrene-based thermoplastic elastomer has DOP as a first plasticizer for a hard segment.
And phthalic acid esters such as "Diana Process Oil" PW-90 "," P
W-300 ”) can provide a high-performance elastic body having shock absorption and flexibility. The phthalic acid ester is 5 to 500 parts by weight, and the process oil is 100 to 100 parts by weight of the polystyrene-based thermoplastic elastomer.
It is preferable to use it in the range of 1500 parts by weight. Further, since the phosphate plasticizer is effective for imparting flame retardancy, it may be used as the first plasticizer in addition to the phthalate.

In addition to the above-mentioned thermoplastic elastomer and two or more plasticizers, fine hollow particles may be added to the elastic body of the present invention for the purpose of weight reduction and cost reduction. Examples of the fine hollow particles include a glass balloon (for example, “CEL-STAR Z” series: manufactured by Asahi Glass Co., Ltd.) and a shirasu balloon (for example, “Gallolite”: manufactured by Shiraishi Industry Co., Ltd.
"Philite": made in the United Kingdom, provided by Japan Philite, "Terraballoon" and "Terafine": made by Calsheet Co., Ltd., porous calcium carbonate (for example, "Callite-K")
T "Shiroishi Central Research Laboratory) Inorganic materials such as silica balloon, fly ash balloon, alumina, zirconia, and pitch, and polymers such as phenol, polyvinyl alcohol, polyvinylidene chloride, epoxy resin, and urea resin Materials can be used.

Among them, the particles made of a polymer material are not only effective in reducing the weight but also can be deformed by an external force, so that they are effective in improving the shock absorbing power and can be preferably used. In particular, a polyvinylidene chloride-based compound obtained by slightly copolymerizing acrylonitrile with vinylidene chloride is preferable because of its excellent deformability. Specifically, “Expancel DE” (manufactured by Swance Expancel, average particle size of 40 to 60 μm) in which butene gas is filled in the outer shell of polyvinylidene chloride, or Micros by Matsumoto Yushi There are fair series. These fine hollow particles are preferably used in a range of 1 to 10% by weight in the elastic body. If it is less than 1% by weight, the effect of weight reduction is not exhibited, and
If it exceeds 0% by weight, it is difficult to mix with the raw materials during production. The size of the fine hollow particles is not particularly limited, and may be several μm to several hundred μm.
m are available. The use of these fine hollow particles has the effect of reducing weight and reducing costs at the same time, and also has the effect of improving fuel efficiency by being used as seats for motorcycles and passenger cars and other shock absorbing materials.

The method for producing the elastic body of the present invention is not particularly limited. For example, the plasticizer is dropped and mixed from the middle of the extruder while heating according to the softening temperature of the thermoplastic elastomer using a twin-screw extruder or the like. Alternatively, a molding method used for thermoplastic elastomers, such as kneading a thermoplastic elastomer and a plasticizer and other materials in a separate batch, and extruding and molding with an extruder, may be used.

[0022]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which do not limit the present invention.
Modifications and alterations that do not depart from the spirit described below are all included in the technical scope of the present invention. In the following examples, “parts” means “parts by weight”. The characteristic evaluation methods used in the following examples and comparative examples are as follows.

[Storage elastic modulus and tan δ] The dynamic viscoelasticity frequency dispersion at a temperature of 25 ° C. was measured based on JIS K7198 using a dynamic viscoelasticity measuring apparatus “DVA-200” manufactured by IT Measurement Control Co., Ltd. . Table 1 shows values at frequencies of 100 Hz, 10 Hz, 1 Hz, and 0.1 Hz. The chuck span was 10 mm. Note that MPa
(Megapascal) is a value equal to 0.101972 kgf / mm ² .

Example 1 A thermoplastic elastomer ("Septon 405" manufactured by Kuraray Co., Ltd.)
5 "; the hard segment is polystyrene, the soft segment is polyethylene and polypropylene, and the weight of the polystyrene portion is 30% by weight) In the ☆☆ part, DOP (di (2-ethylhexyl) phthalate; large) is used as a plasticizer for the hard segment. 35 parts, and 175 parts of process oil ("Diana Process Oil" PW-90 ", manufactured by Idemitsu Oil Co., Ltd.) as a plasticizer for the soft segment, kneaded while heating, and extruding from an extruder. Thus, an elastic body was produced. Table 1 shows tan δ and storage modulus of this elastic body.

Comparative Examples 1 to 3 Only the thermoplastic elastomer used in Example 1 (Comparative Example 1), a thermoplastic elastomer obtained by adding 500 parts of process oil “PX-90” to ☆ parts (Comparative Example 2), Only the commercially available flexible thermoplastic elastomer (“Cosmogel” manufactured by Cosmo Keiki Co., Ltd .; a thermoplastic elastomer to which a plasticizer for a soft segment is added) (Comparative Example 3) was used to prepare an elastic body in the same manner as in Example 1. Produced. Table 1 also shows tan δ and storage elastic modulus of these elastic bodies.

[0026]

[Table 1]

As is clear from Table 1, in the examples of the present invention, the storage elastic modulus is lower by 2 orders and the tan δ is higher by 1 order compared to Comparative Example 1 using only the thermoplastic elastomer. It can be seen that the plasticizing effect of the plasticizer is suitably exhibited. Further, the elastic body of the embodiment of the present invention has a storage elastic modulus of 0.014 to 0.17 MPa,
Loss tangent (tan δ) is in the range of 0.3 to 1.0,
It was confirmed that it had a moderate elastic recovery force that was flexible and excellent in shock absorption.

Further, in Comparative Example 2 in which only the plasticizer for the soft segment was added to the same thermoplastic elastomer as in Example 1, the storage elastic modulus was at the same level, but tan δ
Is smaller than that of Example 1, indicating that the shock absorption is inferior. On the other hand, in Comparative Example 3 using a fairly flexible thermoplastic elastomer, tan δ and storage modulus were smaller than those in Example 1.

[0029]

According to the present invention, even when the thermoplastic elastomer alone has high rebound resilience and is inferior in flexibility, the characteristics of the thermoplastic elastomer can be improved by using a plasticizer for the hard segment and a plasticizer for the soft segment in combination. Can be easily changed. Therefore, by using a thermoplastic elastomer and two or more plasticizers, it was possible to easily obtain an elastic body which is the object of the present invention and is flexible and has an appropriate elastic recovery force.

The elastic body of the present invention can be used as a seat for automobiles, motorcycles and other vehicles, or as a cushion material for handles, handle grips, steps, headrests, etc., and absorbs vibration to reduce pain and fatigue. It has. It is also suitable as a cushioning material for bedding, a cushioning material for sports shoes or shoe soles, etc., and has an effect of suppressing bedsore and reducing the impact of ground contact during exercise. The elastic body of the present invention can be applied to a wide range of fields as various members such as ceiling materials, door trim materials, pad materials and the like, heat insulating materials, sound absorbing materials, cushioning materials and the like, in addition to the above uses. Furthermore, if minute hollow particles are blended into the elastic body and used, the weight can be reduced in each application, which is effective in improving the commercial value.

Claims (3)

[Claims] 1. An elastic body mainly composed of a thermoplastic elastomer composed of a hard segment and a soft segment, wherein at least two types of plasticizers are compounded in the thermoplastic elastomer. Elastic body. 2. The method according to claim 1, wherein at least a first plasticizer capable of plasticizing the hard segment and a second plasticizer capable of plasticizing the soft segment are blended. Elastic body. 3. The elastic body according to claim 1, wherein the thermoplastic elastomer is a polystyrene-based thermoplastic elastomer.