JP2013040310A - Urethanic thermoplastic elastomer composition, and exterior part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a urethanic thermoplastic elastomer composition excellent in all of durability, vibrationproofness, shock-absobance and moldability, and exterior parts using the same.SOLUTION: The urethanic thermoplastic elastomer composition contains: a polycarbonate-based thermoplastic elastomer (A) having a tanδ peak temperature of ≥10°C and ≤50°C and a peak value thereof of 1.0; and a urethanic thermoplastic elastomer (B) which is both of or one of an adipate ester-based urethanic thermoplastic elastomer and a polycaprolactone ester-based urethanic thermoplastic elastomer having a tanδ peak temperature of ≥-40°C and <10°C and a peak value thereof of <1.0, and has a durometer hardness prescribed in JIS K6253 of ≥A70°.

Description

  The present invention relates to a urethane-based thermoplastic elastomer composition that can be used as an exterior component such as a rubber foot for fixing an electronic device product such as a personal computer, and an exterior component composed of the urethane-based thermoplastic elastomer composition.

  Polyester thermoplastic elastomers are known as materials for exterior parts of electronic equipment products such as personal computers. Polyester thermoplastic elastomers have excellent moldability under practical conditions during injection molding, such as a short cooling time during molding and are not prone to sink, and durability as an exterior member with relatively excellent wear resistance. It has advantages such as goodness.

However, in recent years, as electronic devices such as mobile terminals have become highly functional and miniaturized, requirements for protection of electronic components inside the electronic devices have increased. Specifically, in order to protect electronic components from external vibrations and shocks, higher anti-vibration performance and buffer performance are required.
From the viewpoint of vibration proofing and buffering properties, polyester-based thermoplastic elastomers have the drawback of having low vibration proofing properties although they have buffering properties according to the hardness of the material itself.
Materials other than polyester-based thermoplastic elastomers include styrene-based thermoplastic elastomers, which have been conventionally used as vibration-proof materials, but have low wear resistance and are insufficiently durable as exterior parts. There were drawbacks.
Further, the urethane-based thermoplastic elastomer is known as an adhesive member having excellent adhesiveness and deformability. For example, although there is a description in JP-A No. 2003-86961 (Patent Document 1), vibration proofing and buffering properties are known. No urethane-based thermoplastic elastomer having excellent moldability has been known.

JP 2003-86961 A

  Thus, conventional thermoplastic elastomers can be molded into a predetermined shape in a short time, with durability such as wear resistance, anti-vibration properties that attenuate external vibrations, buffering properties that mitigate external shocks, etc. A thermoplastic elastomer excellent in all moldability has not been known.

  Accordingly, the present invention has been made to solve the above-mentioned problems, and a urethane-based thermoplastic elastomer composition which is a thermoplastic elastomer excellent in all of durability, vibration proofing properties, buffer properties, and moldability, and the urethane-based composition thereof It is an object of the present invention to provide an exterior part using a thermoplastic elastomer composition.

In order to achieve the above object, the present invention is configured as follows.
That is, the peak temperature of loss tangent (hereinafter also referred to as “tan δ”) is 10 ° C. or more and 50 ° C. or less, and the urethane thermoplastic elastomer (A) whose peak value is 1.0 or more, and the peak temperature of tan δ is Urethane-based thermoplastic elastomer (B) having a peak value of less than 1.0 and a peak value of less than 1.0, and a durometer hardness according to JIS K6253 of A70 ° or more. It is an elastomer composition.

The urethane-based thermoplastic elastomer (A) having a peak temperature of tan δ of 10 ° C. or more and 50 ° C. or less and a peak value of 1.0 or more is easy to exhibit vibration proofing properties but has a small proportion of hard segments and moldability. Is inferior. Further, since the peak temperature of tan δ is high, the buffering property is inferior.
On the other hand, the urethane-based thermoplastic elastomer (B) having a peak temperature of tan δ of −40 ° C. or more and less than 10 ° C. and a peak value of less than 1.0 has moldability and buffering although it is somewhat difficult to prevent vibration. May improve the performance.
The urethane-based thermoplastic elastomer composition containing both the urethane-based thermoplastic elastomer (A) and the urethane-based thermoplastic elastomer (B) is excellent in vibration proofing, buffering properties, and moldability. Since the durometer hardness specified in K6253 is A70 ° or more, it is a urethane-based thermoplastic elastomer composition excellent in durability.

The durometer hardness defined by JIS K6253 of the urethane-based thermoplastic elastomer (B) is harder than the durometer hardness defined by JIS K6253 of the urethane-based thermoplastic elastomer (A).
Urethane thermoplastic elastomer (B) and durometer hardness specified in JIS K6253 are harder than JIS K6253 durometer hardness of urethane thermoplastic elastomer (A), so urethane thermoplastic elastomer (A) and urethane heat The proportion of the soft segment of the urethane-based thermoplastic elastomer (A) and the proportion of the hard segment of the urethane-based thermoplastic elastomer (B) are relatively increased with the plastic elastomer (B). Thus, a composition having a good balance between vibration proofing, buffering and moldability can be obtained.

  The urethane-based thermoplastic elastomer (A) is a polycarbonate-based urethane-based thermoplastic elastomer, and the urethane-based thermoplastic elastomer (B) is either or both of an adipate ester-based urethane thermoplastic elastomer and a polycaprolactone ester-based urethane-based thermoplastic elastomer. On the other hand, it can be a urethane-based thermoplastic elastomer composition.

  The urethane-based thermoplastic elastomer (A) is a polycarbonate-based urethane-based thermoplastic elastomer, and a composition excellent in vibration-proofing properties can be obtained. In addition, since the urethane-based thermoplastic elastomer (B) is one or both of an adipate ester-based urethane thermoplastic elastomer and a polycaprolactone ester-based urethane-based thermoplastic elastomer, it has excellent durability, buffering properties and moldability. A composition can be obtained. And since it is a mixed composition containing both, it can be set as the urethane type thermoplastic elastomer composition which can shape | mold the solidified material excellent in durability, vibration proof property, buffer property, and a moldability.

And it is a urethane type thermoplastic elastomer composition whose peak temperature of loss tangent is -20 degreeC-30 degreeC, and the peak value is 0.45 or more.
The loss tangent peak temperature is −20 ° C. to 30 ° C., the peak value is 0.45 or more, and the urethane-based thermoplastic elastomer composition is substantially 1.0 or less. It is a urethane-based thermoplastic elastomer composition excellent in properties, buffer properties and moldability.

As the urethane thermoplastic elastomer (A) and the urethane thermoplastic elastomer (B), urethane thermoplastic elastomers compatible with each other can be used.
Since the urethane-based thermoplastic elastomer (A) and the urethane-based thermoplastic elastomer (B) are compatible with each other, the tan δ peak temperature and peak value in the case of each urethane-based thermoplastic elastomer alone are A shifted new peak temperature and peak value can be obtained.

  And the exterior components which consist of these urethane type thermoplastic elastomer compositions are provided. Since the exterior part is made of the urethane-based thermoplastic elastomer composition, it is an exterior part that is excellent in durability, vibration proofing property, buffer property, and moldability.

  According to the urethane-based thermoplastic elastomer composition of the present invention and an exterior part using the same, it is possible to provide an exterior part that is excellent in durability, vibration proofing, buffering property, and moldability.

It is a table | surface which shows the composition of each sample, and various test results. It is a schematic sectional drawing explaining an impact buffering test apparatus. It is explanatory drawing of the aluminum plate seen from the direction shown by arrow A of the shock absorbing test apparatus shown in FIG.

The urethane-based thermoplastic elastomer composition that solves the problems of the present invention will be described in more detail based on specific embodiments.
The urethane-based thermoplastic elastomer has a peak temperature of tan δ of 10 ° C. or more and 50 ° C. or less, and a urethane-based thermoplastic elastomer (A) having a peak value of 1.0 or more, and a peak temperature of tan δ of −40 ° C. or more. It is a thermoplastic elastomer composition containing a urethane-based thermoplastic elastomer (B) having a peak value of less than 10 ° C. and a peak value of less than 1.0. Hereinafter, these components will be described.

The urethane-based thermoplastic elastomer (A) has a peak temperature of tan δ of 10 ° C. or higher and 50 ° C. or lower and a peak value of 1.0 or higher, and can impart high vibration resistance to the composition. Such urethane-based thermoplastic elastomers (A) include polycarbonate-based urethane-based thermoplastic elastomers.
The urethane-based thermoplastic elastomer (B) has a tan δ peak temperature of −40 ° C. or higher and lower than 10 ° C., a peak value of less than 1.0, a low tan δ peak temperature, and a soft segment in the molecule. Has a flexible molecular structure. Further, since the peak value of tan δ is less than 1.0, the proportion of soft segments in the molecule is small. In other words, the amount of hard segments is large and the moldability is excellent. Examples of such urethane thermoplastic elastomers (B) include adipate ester urethane thermoplastic elastomers and polycaprolactone ester urethane thermoplastic elastomers.

And the durometer hardness of JIS K6253 regulation of a thermoplastic elastomer composition is A70 degrees or more. This is because if the durometer hardness specified in JIS K6253 is smaller than A70 °, the softness increases, so that wear resistance becomes a problem particularly when the exterior part is exposed on the surface.
And it is preferable that the durometer hardness of JIS K6253 regulation of urethane type thermoplastic elastomer (B) is harder than the hardness of urethane type thermoplastic elastomer (A).

  Here, when comparing the tan δ peak temperatures of the urethane-based thermoplastic elastomer (A) and the urethane-based thermoplastic elastomer (B), the tan δ of the urethane-based thermoplastic elastomer (B) has a lower peak temperature. . In general, in the same type of composition, the lower the peak temperature of tan δ, the higher the degree of freedom of movement of the molecular chain, and the more tend to be flexible. However, here, contrary to the above relationship, the hardness of the urethane-based thermoplastic elastomer (B) is set to be harder than the hardness of the urethane-based thermoplastic elastomer (A). This indicates that the proportion of the soft segment is relatively large in the urethane-based thermoplastic elastomer (A), while the proportion of the hard segment is large in the urethane-based thermoplastic elastomer (B). That is, by satisfying the above-mentioned hardness relationship, in the urethane-based thermoplastic elastomer (A), the proportion of the soft segment is increased, so that the vibration-proof property and flexibility are improved, and the urethane-based thermoplastic elastomer (B). In this case, the moldability can be improved by increasing the proportion of the hard segment to increase the crystallization speed.

  Since both the urethane-based thermoplastic elastomers (A) and (B) are urethane-based compositions, they can be easily compatible with each other, and when both are highly transparent, the mixed composition is also transparent. Can be a good composition. In particular, the polycarbonate-based urethane-based thermoplastic elastomer, the adipate ester-based urethane-based thermoplastic elastomer, and the polycaprolactone ester-based urethane-based thermoplastic elastomer have good compatibility, and as the urethane-based thermoplastic elastomers (A) and (B), These urethane-based thermoplastic elastomers are preferably used. Such a highly transparent mixed composition is preferable because it can improve the color development even when it is colored.

On the other hand, ether urethane thermoplastic elastomers are difficult to handle among urethane thermoplastic elastomers (B).
This is because the polyether-based urethane-based thermoplastic elastomer is incompatible with the polycarbonate-based urethane-based thermoplastic elastomer useful as the urethane-based thermoplastic elastomer (A). When the urethane thermoplastic elastomers (A) and (B) are incompatible, it is difficult to shift the peak temperature of tan δ to the low temperature side. Therefore, it is difficult to adjust the peak temperature of tan δ by mixing the two components, and it is difficult to increase the buffering property by shifting the peak temperature of tan δ to the low temperature side.

  Various additives can be added to the thermoplastic elastomer as long as the durability, vibration proofing property, buffering property and moldability are not impaired. For example, in order to improve flame retardancy, a flame retardant is added, or in order to increase the miscibility of urethane thermoplastic elastomer (A) and urethane thermoplastic elastomer (B), other urethane thermoplastic elastomers are added. It can also be added. In addition, various additives such as an antioxidant and an anti-aging agent can be included to improve various functions.

  The thermoplastic elastomer composition can be produced by kneading the urethane thermoplastic elastomer (A) and the urethane thermoplastic elastomer (B). The kneading can be performed, for example, by heating to about 200 ° C. using a twin screw extruder.

Preparation of Sample : As examples or comparative examples of the present invention, urethane-based thermoplastic elastomer compositions of Sample 1 to Sample 13 shown below were prepared and subjected to various evaluation tests.

  The urethane-based thermoplastic elastomer used in the thermoplastic elastomer compositions of Samples 1 to 12 is a polycarbonate-based urethane-based thermoplastic elastomer having a tan δ of 1.34 at a peak temperature of 32 ° C., and tan δ of 0.003 at a peak temperature of −37 ° C. 57 polycaprolactone ester urethane thermoplastic elastomer (A), tan δ is 0.26 at a peak temperature of −16 ° C. and 0.26 polycaprolactone ester urethane thermoplastic elastomer (A), tan δ is 0.32 at a peak temperature of 5 ° C. Adipate ester urethane thermoplastic elastomer, tan δ is an ether urethane thermoplastic elastomer (U) having a peak temperature of −2.6 ° C. of 0.31, and tan δ is an ether of 0.27 at a peak temperature of −7.7 ° C. -Based urethane-based thermoplastic elastomer (D). Among these six types of urethane-based thermoplastic elastomers, a predetermined urethane-based thermoplastic elastomer shown in FIG. 1 was kneaded at a predetermined ratio to produce Samples 1 to 12 (In FIG. The “urethane-based thermoplastic elastomer” is described as “polycarbonate-based TPE.” The term “urethane-based” is also omitted for the other urethane-based thermoplastic elastomers described above). For comparison, sample 13 was a styrene thermoplastic elastomer having a tan δ of 0.80 at a peak temperature of 23 ° C. These samples 1 to 13 were subjected to various tests on durability, vibration proofing, buffering properties and moldability. Samples 14 and 15 were used for the ether-based urethane thermoplastic elastomer (c) and the ether-based urethane thermoplastic elastomer (d), respectively.

Measurement of tan δ: tan δ was measured at a temperature of 23 ° C. and a frequency of 28 Hz using a dynamic viscoelasticity measuring device (Seiko Instruments, DMS6100) with a tensile sine wave mote. The test piece used was a 1 mm thick sheet punched out to 10 mm × 40 mm × 1 mmt.
With respect to tan δ thus measured for Sample 1 to Sample 12, the tan δ value at 23 ° C. and 28 Hz, the tan δ peak value, and the temperature at which the peak value is reached are shown in FIG.

Durability test : To test the abrasion resistance, a Taber abrasion test and a crawling test were conducted. Details of the Taber abrasion test and the crawling test are as follows.
The Taber abrasion test is performed on a test piece having a diameter of 130 mm and a thickness of 2 mm using a Taber abrasion tester (AB-101, manufactured by Tester Sangyo Co., Ltd.) under the conditions of an H-22 wear wheel, a load of 1 kgf, and a rotation speed of 60 rpm. The amount of wear (g) when rotating 500 times was measured.
Further, in the cracking test, an artificial nail made of polycarbonate was pressed against a 2 mmt test piece perpendicularly to the test piece with a load of 500 gf, and the presence or absence of scratches was observed visually when the test piece was rubbed 2 cm. Those that were not scratched were marked with “◯”, and those that were scratched were marked with “x”.

Anti-vibration test : In order to test the anti-vibration property, an excitation test and an iron ball drop test were performed. Details of the vibration test and the ball drop test are as follows.
The vibration test was performed by forming a support leg by molding the thermoplastic elastomer composition of each sample into a rectangular parallelepiped shape. A support leg made of each sample was attached to a vibration test apparatus assembled to support a supported body with four support legs, and the vibration test apparatus was fixed to a vibration table. Then, to determine the constant acceleration 2.94m ^/ s 2 (0.3G), the resonance frequency _f 0 is vibrated in the frequency range of 7Hz~200Hz in the vertical direction (Z direction) (Hz). The transmission magnification Q (dB) was obtained by measuring the acceleration a2 of the supported body with respect to the acceleration a1 of the housing at the resonance frequency f ₀ (Hz) and converting it by a relational expression of 20 Log (a2 / a1). The result of the transmission magnification Q is also shown in FIG.

  In the iron ball drop test, the maximum height when an iron ball having a diameter of 11 mm and a weight of 5.5 g is dropped freely from a height of 20 cm onto a test piece having a thickness of 2 mm in an environment of room temperature 23 ° C. and bounces back. Was measured. And when the maximum height at that time is 1 cm or less, “1”, when it exceeds 1 cm and 3 cm or less, “2”, when it exceeds 3 cm and 5 cm or less, “3”, when it exceeds 5 cm and 10 cm or less, “4”, When it exceeded 10 cm and was 15 cm or less, it was set to “5”. It can be said that the lower the maximum height, the higher the anti-vibration property and the better the anti-vibration property.

  For vibration proofing, the transmission magnification is 2 or less “◎”, 2 to 3 or less “O”, 3 to 4 or less “△”, 4 or more “X”, “◎” “ Evaluation was made in four grades: “◯”, “△”, and “×”. Looking at the result of the iron ball drop test, the result is generally in line with this evaluation, and if it is “◯” or more, it can be evaluated that the anti-vibration property is excellent.

Shock buffer test : The shock buffer test was performed by manufacturing the shock buffer test apparatus 11 shown in FIG. A test piece (sample) 13 having a diameter of 20 mm and a thickness of 2 mm is attached to two ends of an aluminum plate 12 having a thickness of 200 mm and a thickness of 4 mm, and the other side of the aluminum plate 12 is fixed by a hinge 14 and inclined at 45 degrees. The maximum acceleration (G) at the time of dropping was measured. The result is shown in FIG.
The maximum acceleration of less than 2100 was evaluated as “◎”, 2100 or more and less than 2500 as “◯”, 2500 or more and less than 3000 as “Δ”, and 3000 or more as “x”.
From the results of the shock buffering test, samples 3, 4 and 7 whose maximum acceleration was less than 2100 were particularly excellent in buffering properties, and samples 1, 2, 5, 8 and 9 whose maximum acceleration was less than 2500 It was found that the buffering property was excellent.

Formability test : Details of the formability test are as follows.
The moldability was evaluated by injecting the composition of each sample into a 30 ° C. mold as an injection molding condition, opening the mold after a solidification time of 30 seconds, and taking out the molded product. In the case of solidification, the surface of the molded body was observed to evaluate whether there was a sink. “X” when not solidified, “Δ” when solidified but there was a sink, and “◯” when there was no sink. Further, under the above conditions, “◎” indicates that no sink marks were observed even when the solidification time was reduced to 15 seconds.

Compatibility : Samples 1 to 5 and Samples 10 to 12 were also evaluated for compatibility. When the raw materials were mixed and transparent and compatible with each other, “◯” was given. When mixed and white turbidity was not found, “X” was given.
Samples 10 to 12 using the ether urethane thermoplastic elastomer were not compatible with the polycarbonate urethane thermoplastic elastomer and had poor buffering properties.

  Based on the above results, urethane thermoplastic elastomers in which polycarbonate urethane thermoplastic elastomers are mixed with polycaprolactone ester urethane thermoplastic elastomers or adipate ester urethane thermoplastic elastomers are durable, vibration proof, and buffered. It can be seen that all of the properties and formability are excellent.

  Further, from the value of tan δ of the above sample, the urethane-based thermoplastic elastomer (A) having a peak temperature of tan δ of 10 ° C. or more and 50 ° C. or less and a peak value of 1.0 or more, and the peak temperature of tan δ is − 40 degreeC or more and less than 10 degreeC, The peak value of the urethane type thermoplastic elastomer (B) whose peak value is less than 1.0 are mixed, The peak temperature of tan-delta is -20 degreeC-30 degreeC, The peak value is A urethane-based thermoplastic elastomer composition having a durometer hardness of 70 ° or more as defined in JIS K6253 is a durable, anti-vibration, shock-absorbing, molded, urethane composition that is 0.45 or more. It turns out that it is excellent in all of sex.

  In addition, the said embodiment is an example of this invention and is not limited to such a form, The arbitrary modification which does not contradict the meaning of this invention is included.

DESCRIPTION OF SYMBOLS 11 Shock absorbing test apparatus 12 Aluminum plate 13 Test piece 14 Hinge

Claims (6)

  Loss tangent (tan δ) peak temperature is 10 ° C. or more and 50 ° C. or less, urethane-based thermoplastic elastomer (A) whose peak value is 1.0 or more, and loss tangent peak temperature is −40 ° C. or more and 10 ° C. And a urethane-based thermoplastic elastomer composition (B) having a peak value of less than 1.0, and a durometer hardness defined in JIS K6253 of A70 ° or more.   The urethane-based thermoplastic elastomer composition according to claim 1, wherein the durometer hardness defined in JIS K6253 of the urethane-based thermoplastic elastomer (B) is harder than the durometer hardness defined in JIS K6253 of the urethane-based thermoplastic elastomer (A).   The urethane-based thermoplastic elastomer (A) is a polycarbonate-based urethane-based thermoplastic elastomer, and the urethane-based thermoplastic elastomer (B) is either or both of an adipate ester-based urethane thermoplastic elastomer and a polycaprolactone ester-based urethane-based thermoplastic elastomer. The urethane-based thermoplastic elastomer composition according to claim 1, which is either one.   The urethane-based thermoplastic elastomer composition according to any one of claims 1 to 3, wherein a peak temperature of loss tangent is -20 ° C to 30 ° C, and a peak value thereof is 0.45 or more.   The urethane-based thermoplastic elastomer composition according to any one of claims 1 to 4, wherein the urethane-based thermoplastic elastomer (A) and the urethane-based thermoplastic elastomer (B) are mutually compatible urethane-based thermoplastic elastomers.   An exterior part comprising the urethane-based thermoplastic elastomer composition according to any one of claims 1 to 5.

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