JP2019070079A - Thermoplastic elastomer composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoplastic elastomer composition having excellent tensile strength and elongation and excellent durability at a high temperature for a long time. A thermoplastic elastomer composition having a continuous phase and a dispersed phase dispersed therein. In the continuous phase, the thermoplastic resin component (A) having a melting point of 170 to 300 ° C. and the rubber component (B) are partially phase-dissolved. The dispersed phase consists of a rubber component. The thermoplastic elastomer composition in which the content of the dispersed phase is 5 to 20% by volume with respect to the total 100% by volume of the continuous phase and the dispersed phase [selection diagram] FIG.

Description

  The present invention relates to a thermoplastic elastomer composition having a continuous phase in which a thermoplastic resin component and a rubber component are partially compatible.

  BACKGROUND ART In recent years, thermoplastic elastomers having rubber elasticity and thermoplasticity are widely used in the fields of automobile parts, home electric appliance parts, electric wire coating, medical parts, footwear, daily goods and the like. Thermoplastic elastomers are superior in moldability to, for example, vulcanized rubber, and can be vulcanized at the time of production of the material, and thus have the advantage of not requiring a separate vulcanization step after molding of the parts. .

  In particular, thermoplastic elastomers in which a mixture of rubber and a thermoplastic resin is dynamically crosslinked in the presence of a crosslinking agent is said to be useful, particularly in the field of seal parts where vulcanized rubber was conventionally used. There is. However, thermoplastic elastomers are harder and less likely to have permanent set characteristics than vulcanized rubbers.

  In order to use thermoplastic elastomers, for example, as automobile parts, further improvement of properties such as flexibility, heat resistance, oil resistance and permanent set resistance is required. There are also several proposals aimed at improving these. For example, Patent Document 1 proposes a thermoplastic elastomer composition containing a polyamide-based polymer, a carboxyl group-containing acrylic rubber, and an epoxy group-containing polymer for the purpose of improving flexibility, heat resistance, oil resistance, etc. .

JP, 2016-121227, A

  The above-described conventional thermoplastic elastomer controls the interface between the rubber and the resin by reacting a carboxy group and an epoxy group, and has a configuration in which the boundary between the two is clear. Although the thermoplastic elastomer having such a constitution improves the tensile strength and the elongation as compared with the thermoplastic elastomer in which the interface control is not performed, the present condition is that the characteristics are still insufficient.

  Also, with conventional thermoplastic elastomers, for example, the hardness and seal characteristics have not been studied after a high temperature durability test for a long time exceeding 1000 hours. Therefore, it is a fact that the application to vehicle parts such as, for example, a car that requires high temperature and long time durability has not been realized yet.

  In addition, in the above-mentioned conventional thermoplastic elastomer, acrylic rubber is hydrolyzed by water contained in fuel and oil. Therefore, the range of use is limited, and it can not be applied to parts in contact with oil, such as around fuel, of a vehicle.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a thermoplastic elastomer composition which is excellent in tensile strength and elongation and excellent in long-term durability at high temperature.

One embodiment of the present invention is a continuous phase in which a thermoplastic resin component (A) having a melting point of 170 to 300 ° C. and a rubber component (B) are partially compatible,
A dispersed phase comprising the rubber component (B) dispersed in the continuous phase;
The thermoplastic elastomer composition according to claim 1, wherein the content of the dispersed phase is 5 to 20% by volume with respect to a total of 100% by volume of the continuous phase and the dispersed phase.

  The thermoplastic elastomer composition has a continuous phase and a dispersed phase dispersed in the continuous phase. In the continuous phase, the hard thermoplastic resin component (A) and the rubber component (B) excellent in flexibility and permanent set resistance are partially compatible, and the dispersed phase is composed of the rubber component (B). Furthermore, the content of the dispersed phase is within the above-mentioned predetermined range. As described above, the thermoplastic resin composition has a configuration in which the content of the dispersed phase is within the above-described predetermined range while having the continuous phase in which the thermoplastic resin component (A) and the rubber component (B) are partially compatible with each other. The elastomeric composition exhibits excellent flexibility in the continuous phase. Thus, the thermoplastic elastomer composition can exhibit mechanical properties such as, for example, excellent tensile strength and elongation comparable to those of vulcanized rubber. Hereinafter, the thermoplastic resin component (A) is appropriately referred to as a resin component (A).

  Further, in the thermoplastic elastomer composition, the resin component (A) having excellent oxygen barrier properties forms a continuous phase. Therefore, the oxidative degradation of the rubber component (B) compatible with the resin component (A) and the rubber component (B) forming the dispersed phase dispersed in the continuous phase is suppressed. Therefore, the thermoplastic elastomer composition exhibits a small change in properties even when exposed to high temperatures for a long time, and can suppress, for example, hardening due to oxidative degradation and generation of a permanent set due to an increase in compression set. That is, it is excellent in high temperature durability.

  In addition, the thermoplastic elastomer composition is less deteriorated by hydrolysis and the like even in an oil environment. Therefore, the thermoplastic elastomer composition is suitable, for example, as a seal component used around a fuel tank of a vehicle, around an engine, around an exhaust pipe and the like.

  As mentioned above, according to the above-mentioned mode, it is possible to provide a thermoplastic elastomer composition which is excellent in tensile strength and elongation and also excellent in long-term durability at high temperature. The reference numerals in parentheses described in the claims and the means for solving the problems indicate the correspondence with the specific means described in the embodiments described later, and the technical scope of the present invention is limited. It is not a thing.

The graph which shows the increase rate of the hardness of each Example and each comparative example. The graph which shows the increase rate of the compression set of each Example and each comparative example.

  A preferred embodiment of the thermoplastic elastomer composition will be described. The thermoplastic elastomer composition has a continuous phase and a dispersed phase, and has a phase structure in which a plurality of dispersed phases are dispersed in the continuous phase. Usually, a phase structure in which a large number of dispersed phases are dispersed in a continuous phase is obtained. The morphology of such a phase separation structure consisting of a continuous phase and a dispersed phase is sometimes referred to as a sea-island structure.

[Continuous phase]
The continuous phase is an amorphous and continuous phase in observation of the phase separation structure in the thermoplastic elastomer composition. The continuous phase is sometimes called the sea phase. The continuous phase contains the resin component (A) and the rubber component (B), and both are partially compatible. Here, partial compatibility refers to the state in which the molecular chain of the resin component (A) enters the polymer constituting the rubber component (B), or conversely, the rubber component (A) of the resin component (A) The state in which the molecular chain of B) has entered.

  The presence or absence of partial compatibility is determined as follows. First, the thermoplastic elastomer composition is subjected to a dyeing process with a dyeing agent capable of dyeing the resin component (A) and the rubber component (B). The staining process can be performed by a known staining technique. The thermoplastic elastomer composition treated with each staining agent is observed with an electron microscope, the observation result is image-analyzed, the volume ratio is calculated, and the determination can be made by comparing the results. Specifically, as a result of comparing the volume ratio of each dyed area between the composition obtained by dyeing the resin component and the composition obtained by dyeing the rubber component, when there is a difference of 10% by volume or more in the volume ratio of both, It is determined that a compatible continuous phase is present. This is because there is an overlapping area in the staining area with each staining agent in the compatible part. On the other hand, when the difference in volume ratio between the two is less than 10% by volume (including 0), it is determined that there is no partially compatible continuous phase. Each staining is performed on three samples, and the determination of the presence or absence of partial compatibility is performed based on the arithmetic mean of these volume ratios. In addition, the dispersed phase which consists of a rubber component observes the thermoplastic elastomer composition which dye | stained the resin component, and says the thing of the part which was not dyed.

  As a staining agent, phosphotungstic acid, osmium tetraoxide, ruthenium tetraoxide or the like can be used. For example, phosphotungstic acid stains amide bonds in polyamide resins. For example, osmium tetroxide is commonly used to stain rubber components, which are stained selectively in response to double bonds. For example, ruthenium tetraoxide is dyed by introducing a heavy metal by the oxidation reaction and the crosslinking reaction of the noncrystalline part, so that dyeing of polyolefin resin or polyester resin is possible. The type of staining agent can be selected according to the type of resin component (A) and the type of rubber component (B).

<Thermoplastic resin>
In the present specification, the thermoplastic resin is a concept not including rubber. The melting point of the resin component (A) is 170 to 300 ° C. If the melting point is less than 170 ° C., the heat resistance may be poor, and for example, the heat resistance required for automotive applications may not be satisfied. From the viewpoint of further improving the heat resistance, the melting point of the resin component (A) is preferably 200 ° C. or more, and more preferably 230 ° C. or more. On the other hand, when the melting point exceeds 300 ° C., the rubber component (B) may be deteriorated during the kneading of the resin component (A) and the rubber component (B) at the time of production of the thermoplastic elastomer composition. From the viewpoint of further suppressing the deterioration of the rubber component (B), the melting point of the resin component (A) is preferably 290 ° C. or less, more preferably 260 ° C. or less.

  The resin component (A) is, for example, polyamide resin (that is, PA resin), polyacetal resin (that is, POM resin), modified polyphenylene ether resin (that is, m-PPE), polyvinyl alcohol resin (that is, PVA resin), polyphenylene sulfide Phenized resin (that is, PPS resin), polyvinylidene chloride resin (that is, PVDC resin), polyvinylidene fluoride resin (that is, PVDF resin), fluorine resin, polysulfone resin (that is, PSU resin), polyether sulfone resin (that is, PESU resin), polyarylate resin (that is, PAR resin), liquid crystal polymer (that is, LCP resin), polyether ketone resin (that is, PEK resin), polyether ether ketone resin (that is, PEEK resin), polyether imide resin (Tatsuma , PEI resin), polyamide imide resin (that is, PAI resin), thermoplastic polyimide (that is, TPI resin), cyclic olefin resin (that is, COP resin), polyolefin resin (PO resin), vinyl chloride resin (that is, PVC resin) And polyethylene terephthalate resin (that is, PET resin), polybutylene terephthalate (that is, PBT resin), and the like. The resin component (A) may consist of one type of resin, and may consist of two or more types of resin. Preferably, the resin component (A) is a crystalline resin.

(Polyamide resin)
The main component of the resin component (A) is preferably a polyamide resin. In this case, the oxygen barrier properties and oil resistance of the continuous phase are further improved. Thereby, the oxidative degradation of the rubber component (B) compatible with the thermoplastic resin and the rubber component (B) forming the dispersed phase dispersed in the continuous phase is suppressed. Therefore, the high temperature durability of the thermoplastic elastomer composition is further improved. In the present specification, the polyamide resin is a thermoplastic resin having an amide bond (-CONH-) in the main chain as a repeating unit.

  The main component of the resin component (A) means that it is the largest component in the thermoplastic resin, and is, for example, 50% by mass or more. The content of the polyamide resin in the resin component (A) is preferably 80% by mass or more, and more preferably 90% by mass or more. It is more preferable that the thermoplastic resin (A) substantially consists of a polyamide resin. "Consisting essentially of a polyamide resin" means that the resin component (A) is composed of a polyamide resin excluding unavoidable impurities.

  Examples of polyamide resins include poly coupleramide (polyamide 6), porundecane amide (polyamide 11), polylaurinamide (polyamide 12), polyhexamethylene adipamide (polyamide 66), polyhexamethylene sebacamide (polyamide 610), etc. Aliphatic polyamides can be used. Further, as polyamide resins, aromatic polyamides such as polyhexamethylene terephthalamide (polyamide 6T), polyhexamethylene isophthalamide (polyamide 6I), polynonamethylene terephthalamide (polyamide 9T) and the like can be used. The polyamide resin which can be used is not limited to these. The polyamide resin may be one kind or a mixture of two or more kinds of resins.

  The polyamide resin is preferably made of at least one selected from the group consisting of polyamide 6, polyamide 11, polyamide 12, and polyamide 610. In this case, the oil resistance, heat resistance, mechanical strength and flexibility of the continuous phase are further improved, and the tensile strength, elongation, durability and the like of the thermoplastic elastomer composition can be improved. It is also advantageous in terms of cost reduction.

  As the polyamide resin, polyamide 12 is more preferable. In this case, the water absorption of the continuous phase is reduced, the shape stability is improved, and the cold shock resistance is improved. Therefore, it is possible to improve the moisture resistance and the low temperature durability of the thermoplastic resin elastomer composition. In addition, since the melting point is lower than that of other polyamides, the control of the viscosity ratio between the polyamide resin and the rubber at the time of melting becomes easy. As a result, it becomes easy to knead | mix a thermoplastic-elastomer composition.

<Rubber>
It is preferable to select a combination in which the solubility parameter (that is, the SP value) is close to the rubber component (B) and the resin component (A). In this case, the affinity between the two is good, and the formation of a partially compatible continuous phase is facilitated. As such a combination, for example, when the thermoplastic resin is a polyamide resin, hydrogenated nitrile rubber can be used.

  The rubber component (B) can contain, for example, hydrogenated nitrile rubber, nitrile rubber, acrylic rubber, ethylene propylene rubber, butyl rubber, silicone rubber and the like. The rubber component (B) may consist of one type of rubber, and may consist of two or more types of rubber.

  The rubber component (B) preferably contains a hydrogenated nitrile rubber, and more preferably the main component of the rubber component (B) is a hydrogenated nitrile rubber. In this case, the heat resistance and oil resistance of the thermoplastic elastomer composition are improved. The main component of the rubber component (B) means that it is the largest component in the rubber component (B) and is, for example, 50% by mass or more. The content of the hydrogenated nitrile rubber in the rubber component is preferably 80% by mass or more, more preferably 90% by mass or more. More preferably, the rubber component (B) consists essentially of hydrogenated nitrile rubber. "Consisting essentially of hydrogenated nitrile rubber" means that the rubber component (B) is made of hydrogenated nitrile rubber except for unavoidable impurities.

(Hydrogenated nitrile rubber)
A hydrogenated nitrile rubber is a rubber in which the carbon-carbon unsaturated bond of the main chain in the nitrile rubber is hydrogenated. Nitrile rubber is a rubber obtained by copolymerizing an α, β-ethylenically unsaturated nitrile monomer, a conjugated diene monomer, and other monomers copolymerizable with these, if necessary. It is The content of the component derived from each monomer constituting the rubber can be appropriately adjusted.

[Dispersed phase]
The dispersed phase is, for example, a particulate phase in observation of the phase separation structure in the thermoplastic elastomer composition. The dispersed phase is sometimes called island phase. The shape of the dispersed phase is not particularly limited.

  The dispersed phase comprises the rubber component (B). The rubber described above can be used as the rubber component (B). As described above, in the continuous phase, the resin component (A) and the rubber component (B) are partially compatible. Therefore, the dispersed phase can be regarded as a phase composed of the rubber component remaining without compatibilization with the thermoplastic resin.

  When the content of the dispersed phase in the thermoplastic elastomer composition is increased, the compression set may be increased or the flexibility may be impaired. From the viewpoint of avoiding this, the content of the dispersed phase is preferably 20% by volume or less with respect to 100% by volume in total of the continuous phase and the dispersed phase. The content of the dispersed phase is more preferably 10% by volume or less from the viewpoint of further reducing the compression set and improving the durability at high temperature. In addition, the content of the dispersed phase is preferably 5% by volume or more from the viewpoint of the difficulty of compatibilization during production. The content of the dispersed phase and the continuous phase is expressed by volume ratio.

The average volume of the dispersed phase is preferably 0.3 μm ³ or less. In this case, mechanical properties such as tensile strength and elongation can be further improved. In addition, the hardness can be reduced. From the viewpoint of further enhancing these effects, the average volume of the dispersed phase is more preferably 0.1 μm ³ or less.

[Other ingredients]
The thermoplastic elastomer composition can further contain other components as long as the desired effects of the present invention are not impaired. Examples of such components include compatibilizers, plasticizers, antioxidants, light stabilizers, weathering agents, and flame retardants. These components may be contained in the continuous phase, may be contained in the dispersed phase, or may be contained in both the continuous phase and the dispersed phase.

  The content of the plasticizer is preferably zero or less. In this case, it is possible to suppress the decrease in the gas barrier properties of the continuous phase containing the thermoplastic resin (A). On the other hand, since the flexibility is improved when the content of the plasticizer is increased, the content of the plasticizer can be appropriately adjusted according to the required level of the flexibility.

  In addition, the content of the compatibilizer can be reduced, and may be zero. Thus, even if the content of the compatibilizer is reduced or 0, the thermoplastic elastomer composition has a continuous phase which is partially compatible as described above, and therefore, the flexibility, permanent set resistance, etc. It is possible to improve mechanical characteristics. The content of the compatibilizer can be less than 10 parts by mass with respect to 100 parts by mass of the total amount of the resin component (A) and the rubber component (B). Even if the content of the compatibilizer is reduced, the content of the compatibilizer is 5 parts by mass or less in order to make the effect of improving the mechanical properties more prominent as described above. More preferably, 3 parts by mass or less is more preferable, and 0 is even more preferable.

[Production of Thermoplastic Elastomer Composition]
The thermoplastic elastomer composition is obtained by kneading a thermoplastic resin, a rubber, a crosslinking agent and the like. As a crosslinking agent, an organic peroxide, a sulfur type crosslinking agent, an amine type crosslinking agent, a phenol resin type crosslinking agent etc. can be used, for example. The type and amount of the crosslinking agent can be appropriately changed according to the type of thermoplastic resin and rubber.

  The kneading may be performed once, or, for example, the kneaded material after kneading may be further kneaded by changing the kneading temperature or the like. That is, the kneading may be performed a plurality of times. At the time of kneading, the above-mentioned other components can be further added.

By kneading at a predetermined temperature at the time of kneading, the rubber component (B) can be dynamically crosslinked. It is preferable that the kneading temperature Tk at the time of dynamic crosslinking and the melting point Tm of the thermoplastic resin satisfy the relationship of the following formula (I). In this case, a continuous phase in which the resin component (A) and the rubber component (B) are partially compatible with each other is easily formed, and an effect of improving mechanical characteristics and durability at high temperature can be obtained. The unit of kneading temperature Tk and melting point Tm is ° C.
Tm ≦ Tk ≦ Tm + 10 (I)

From the viewpoint of further promoting partial compatibility in the continuous phase, it is more preferable to satisfy the relationship of the following formula (II).
Tm ≦ Tk ≦ Tm + 5 (II)

  The thermoplastic elastomer composition can be molded by various molding methods. The molded body can be used as a fluid seal component such as an O-ring, a gasket, or a packing. Thereby, the performance of being excellent in tensile strength, elongation, and durability at high temperature can be sufficiently exhibited. Further, the molded article of the thermoplastic elastomer composition is excellent as a gas barrier property, and is less likely to be deteriorated by hydrolysis even in an oil environment such as fuel and engine oil, and thus is suitable as a sealing part for vehicles such as automobiles.

  When a polyamide resin is used as the thermoplastic resin, integral molding with a polyamide resin component used in a fuel or engine oil environment becomes possible, and a seal band can be formed. Therefore, for example, when manufacturing an assembly in which an O-ring or the like is separately assembled, the number of manufacturing steps can be reduced. As a result, it is advantageous in terms of manufacturing cost.

[Example]
Examples of the present invention will be described below, but the present invention is not limited to the following examples. In this example, the thermoplastic elastomer compositions of Examples 1 to 5 are produced, and their properties are evaluated. Moreover, four types of compositions of Comparative Examples 1 to 4 are prepared for comparison with the examples, and the characteristics are evaluated.

Examples 1-5
First, raw materials of the respective examples and comparative examples are shown in Table 1. The melting point Tm of the component A1 shown in Table 1, that is, the polyamide resin is 176 ° C.

  In the production of the thermoplastic elastomer composition of each example, first, the resin component (A) and the rubber component (B) were each weighed at a volume ratio shown in Table 2 described later, and charged into a kneader. As a kneader, a micro-kneading injection kneader manufactured by Imoto Machinery Co., Ltd., model IMC-18D7 was used.

  Next, the resin component (A) and the rubber component (B) were mixed for 30 minutes in the kneader. As mixing conditions in the kneader, the number of rotations is 100 rpm and the temperature is 180.degree.

  After kneading, the kneaded material was once taken out of the kneader. Then, the crosslinking agent (C) was added to the kneaded material. The addition amount of the crosslinking agent (C) with respect to 100 parts by mass of the rubber component (B) is shown in Table 2. The kneaded material to which the crosslinking agent was added was again introduced into the kneader and mixed at a temperature of 100 ° C. for 15 minutes.

  The kneaded material after the second mixing was taken out of the kneader again. Next, the temperature of the kneader was set to the dynamic crosslinking kneading temperature shown in Table 1, and the kneaded material was again introduced into the kneader and mixed for 15 minutes. Thus, the thermoplastic elastomer compositions of Examples 1 to 5 were obtained.

Comparative Example 1
The rubber component (B) and the crosslinking agent (C) were weighed at the mixing ratio shown in Table 2 and charged into a kneader at a temperature of 100 ° C. Next, the rubber component (B) and the crosslinking agent (C) were mixed in a kneader for 15 minutes. Thus, the rubber composition of Comparative Example 1 was obtained.

Comparative Example 2
The mixture of a thermoplastic resin component (A), a rubber component (B), and a crosslinking agent (C) was produced by the compounding ratio shown in Table 2 similarly to Examples 1-5. However, dynamic cross-linking and kneading were not performed in this example. Thus, the composition of Comparative Example 2 was obtained.

Comparative Example 3
The same procedure as in Examples 1 to 5 is performed, except that the compatibilizer (D) is added in the amount shown in Table 2 to 100 parts by mass in total of the thermoplastic resin component (A) and the rubber component (B). The thermoplastic elastomer composition was prepared.

Comparative Example 4
The preparation of the composition was attempted in the same manner as in Examples 1 to 5 at the mixing ratio shown in Table 2. However, since the dynamic crosslinking and kneading temperature increased to 190 ° C. and the rubber component (B) was crosslinked in the continuous phase, no thermoplastic composition was obtained.

  The compositions of the respective examples and comparative examples were pressed at a temperature of 180 ° C. for 10 minutes to form a sheet having a thickness of 0.5 mm. The following tests (1) to (5) were carried out using this sheet-like test piece, and the results are shown in Table 2. In addition, about the comparative example 4, since shaping | molding was impossible, the operation after preparation of a sheet-like test piece is not performed.

(1) Formability The appearance of the sheet-like test piece was examined visually. The case where there was no defect such as air bubbles in the test piece was judged as "good", and the case where there was a defect was judged as "defect".

(2) Morphology A sheet-like test piece was cut in a state of being cooled to liquid nitrogen temperature using an ultramicrotome type UCT1.1 manufactured by Leica, and a sample having a cut surface exposed was produced. The polyamide resin component was dyed by performing a dyeing process by immersing the cut surface of this sample in phosphotungstic acid for 24 hours at normal temperature. Thereafter, using a focused ion beam scanning electron microscope, 100 pieces of SEM images of a 10 μm × 8 μm rectangular area were taken at intervals of 30 nm. Focused ion beam processing and scanning electron microscopy were performed at a temperature of -130 ° C. As the focused ion beam scanning electron microscope, Helios Nanolab 600 manufactured by FEI was used. Each SEM image was binarized by image analysis software and then three-dimensional reconstructed. As image analysis software, ImageJ manufactured by NIH was used, and three-dimensional reconstruction was performed by Avizo manufactured by Maxnet. After identifying the constituents of the continuous phase and the dispersed phase, the volume ratio of the continuous phase and the dispersed phase, and the average volume of the dispersed phase were calculated. The dispersed phase consisting of the rubber component was a portion which was not dyed by phosphotungstic acid. The constituents of the continuous phase and the dispersed phase can be identified by dyeing with a staining agent capable of dyeing the resin component (A) and the rubber component (B). Moreover, about the sample, determination of the presence or absence of partial compatibility was performed by the method as stated above.

(3) Tensile test A tensile test was performed in accordance with JIS K 6251: 2010. Specifically, after making a dumbbell-like No. 7 test piece from a sheet-like test piece by punching, a marked line with a length of 8 mm was marked, and a tensile test was performed under a condition of a tensile speed of 200 mm / min. The maximum stress in the tensile test was taken as tensile strength, and the elongation at break was taken as tensile breaking elongation.

(4) Hardness H. International rubber hardness (i.e., IRHD) was measured according to JIS K 6253: 2012 using a Burleigh's Digitest. Three sheet-like test pieces having a thickness of 0.5 mm were stacked, and the hardness after 15 seconds was measured. This was taken as the initial hardness. In addition, after treating the test piece at a temperature of 120 ° C. for 2000 hours, the hardness was similarly measured. This was taken as hardness as a durable property. In Comparative Example 3, since the hardness at the initial stage was high and the hardness characteristics were insufficient, the evaluation of the durability was omitted. Moreover, about the Examples 1-5, the comparative example 1, and the comparative example 2, the increase rate of the hardness in back and front of a durable characteristic is calculated, and it shows in FIG.

(5) Compression set The compression set was measured in accordance with JIS K 6262: 2013. For the measurement, three sheet-like test pieces having a thickness of 0.5 mm were stacked, and the sheet-like test pieces in a laminated state were used. The laminated sheet-like test piece was subjected to 25% compression deformation, and the compression set after 70 hours at a temperature of 120 ° C. was measured. This was taken as the initial compression set. Further, the laminated sheet-like test pieces were subjected to 25% compression deformation, and the compression set after 2000 hours at a temperature of 120 ° C. was measured. This was taken as the compression set as a durable characteristic. In Comparative Example 3, since the initial compression set was high and the compression set characteristics were insufficient, the evaluation of the durability was omitted. In Examples 1 to 5 and Comparative Examples 1 and 2, the rate of increase in compression set before and after the durability characteristics was calculated, and the results are shown in FIG.

  As known from Table 2, the thermoplastic elastomer compositions of Examples 1 to 5 have a continuous phase in which the resin component (A) and the rubber component (B) are partially compatible. Therefore, it is excellent in tensile strength, elongation, hardness, and compression set, and their balance is good. Furthermore, as is known from Table 2, FIG. 1, and FIG. 2, Examples 1 to 5 have very small changes in hardness and compression set even after heat treatment for a long time at high temperature, and excellent hardness and compression. It showed permanent strain characteristics.

  On the other hand, although the comparative example 1 is excellent in the initial characteristics, the composition was deteriorated by the heat treatment for a long time at a high temperature, and the durability was significantly reduced. Further, in Comparative Example 2, the rubber component was a continuous phase, and the thermoplastic resin component was a dispersed phase. Such a composition is not only thermoplastic but also has the durability characteristics significantly lowered because the rubber component of the continuous phase is deteriorated by heat treatment at high temperature for a long time. Moreover, in the comparative example 3, the resin component which is hard and which is easy to be creep-deformed is a continuous phase, and the rubber component is not compatible in the continuous phase. Therefore, although the comparative example 3 became a thermoplastic composition, the initial stage hardness and the compression set property were inadequate.

  As described above, according to this example, it can be seen that a thermoplastic elastomer composition excellent in tensile strength and elongation as in Examples 1 to 5 and excellent in long-term durability at high temperature can be obtained. The present invention is not limited to the above embodiments, and can be applied to various embodiments without departing from the scope of the invention. For example, it is also possible to use resins other than polyamide resin as a thermoplastic resin component, and to use rubbers other than hydrogenated nitrile rubber as a rubber component.

Claims (5)

A continuous phase in which the thermoplastic resin component (A) having a melting point of 170 to 300 ° C. and the rubber component (B) are partially compatible;
A dispersed phase comprising the rubber component (B) dispersed in the continuous phase;
Thermoplastic elastomer composition whose content of the said dispersed phase is 5-20 volume% with respect to a total of 100 volume% of the said continuous phase and the said dispersed phase.   The thermoplastic elastomer composition according to claim 1, wherein the content of the dispersed phase is 5 to 10% by volume with respect to a total of 100% by volume of the continuous phase and the dispersed phase. The thermoplastic elastomer composition according to claim 1, wherein an average volume of the dispersed phase is 0.3 μm ³ or less.   The thermoplastic elastomer composition according to any one of claims 1 to 3, wherein the thermoplastic resin component (A) is a polyamide resin.   The thermoplastic elastomer composition according to any one of claims 1 to 4, wherein the rubber component (B) is a hydrogenated nitrile rubber.

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