JPH11240999A - Elastomer composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition varied in temperature dependence of viscoelastic characteristics by blending a specific block copolymer with a specified polymer and at least partially cross-linking the resultant blend. SOLUTION: This elastomer composition is obtained by blending (a) a block copolymer having two or more mutually incompatible and two kinds of blocks A and B having different compositions with (b) a polymer compatible with only either one of the two kinds of blocks of the component (a) and at least partially cross-linking the resultant blend. The ratio (k) of the weight-average molecular weight of the component (b) to the weight-average molecular weight of the block compatible with the component (b) in the component (a) is preferably <=1.5 and more preferably 0.05-1.0. The value of the (k) can be varied between 0.05<=(k)<=2.5 to thereby provide a cross-linked elastomer having a different temperature dependence of the viscoelasticity in spite of the polymer composition of the same composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel crosslinked elastomer composition which can arbitrarily change the temperature dependence of viscoelastic properties by blending specific polymers. The present invention also relates to a novel continuous structure elastomer composition which can impart anisotropy to physical properties by changing the molecular weight ratio of each polymer in a blend of specific polymers. Therefore, the crosslinked elastomer composition and the continuous structure elastomer composition according to the present invention are:
It can be effectively used for tires, seismic isolation rubber, vibration damping rubber, various sealing materials and industrial rolls.

[0002]

2. Description of the Related Art Conventionally, technologies relating to engineering resins, such as improving desired properties, adding new functions, or balancing various properties of materials, by blending two or more existing polymers. As a specific means in such a direction, attempts have been made to control the temperature dependence of the viscoelastic properties of the system by blending two or more rubber materials. However, there is no known example of changing the temperature dependence of the viscoelastic properties of an elastomer component having the same composition by changing only the molecular weight.
Further, there is no known example of giving anisotropy to physical properties by the same method.

[0003]

According to the present invention, there is provided a crosslinked elastomer composition in which the temperature dependence of viscoelastic properties is changed by blending, as rubber materials, elastomer components having the same composition but different only in molecular weight. The purpose is to: The present invention also blends a polymer having a specific molecular weight compatible with only one of the block polymers having two (2 or more) blocks that are incompatible with each other and having two different compositions. Accordingly, an object of the present invention is to provide a continuous structure elastomer composition capable of giving anisotropy to physical properties.

[0004]

According to the present invention, (a)
A and B are blended with a block polymer having two or more mutually incompatible blocks of two different compositions and (b) a polymer compatible only with a block of one composition, and at least partially crosslinked. An elastomer composition is provided.

According to the present invention, the ratio k between the weight average molecular weight of the polymer (b) and the weight average molecular weight of the block compatible with the polymer (b) in the block polymer (a) is 1.5 or less. The crosslinked elastomer composition is provided.

According to the present invention, k is set to 0.0.
The crosslinked elastomer composition is provided in which the temperature dependence of viscoelasticity is controlled by changing the value between 5 ≦ k ≦ 2.5.

Further, according to the present invention, (a) a block polymer having two or more mutually incompatible blocks of two different compositions, A and B, and (b) a block polymer having only one composition An elastomer composition is provided wherein the soluble polymer is blended and forms an entirely continuous structure.

According to the present invention, the ratio k between the weight average molecular weight of the polymer (b) and the weight average molecular weight of the block compatible with the polymer (b) in the block polymer (a) is 0.05 ≦. A continuous structure elastomer composition is provided wherein k ≦ 0.35.

According to the present invention, (a) the block polymer is a thermoplastic elastomer, or (a) the block polymer and / or (b) the polymer is a crosslinkable elastomer. A continuous elastomer composition is provided.

Further, according to the present invention, there is provided a continuous structure elastomer composition characterized in that at least a part of either the (a) block polymer or the (b) polymer is crosslinked.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration, operation and effect of the present invention will be described below. In the present invention, a polymer having compatibility with either the polymer chains A or B of the block polymer is used for a block polymer composed of two types of mutually incompatible polymer chains A and B. Or a copolymer) to locally compatibilize the compatible polymer with the polymer chains of the compatible component in the block polymer, thereby causing the block polymer to undergo microphase separation. By utilizing the fact that the morphology of the microdomain changes due to swelling, a novel elastomer composition capable of freely controlling desired physical properties is obtained as a result. Therefore, according to the present invention, a raw material polymer obtained by combining a block polymer composed of the polymer chains A and B and a plurality of compatible polymers different only in the molecular weight compatible with the compatible polymer chain portion is appropriately selected. By blending them at a specific compounding ratio, a crosslinked elastomer composition having a temperature dependency of different viscoelasticity (tan δ) while having a polymer composition of the same composition, A continuous structure elastomer composition having anisotropy in physical properties while being a polymer composition having a composition can be easily obtained.

In the present invention, in order to obtain a crosslinked or continuous structure elastomer composition having desired properties, the molecular weight (weight average molecular weight Mw ₁ ) of the compatible polymer chain portion in the polymer chain A or B of the block polymer is required. An important factor is the ratio k of the molecular weight (weight average molecular weight Mw ₂ ) of the compatible polymer to k, that is, k = Mw ₂ / Mw ₁ . As this ratio k is less smaller than 1, i.e. miscibility weight average molecular weight Mw ₂ is compatible polymer chain weight average molecular weight Mw ₁ if smaller small that its compatibility polymer chains compatible than the block polymer in the polymer Although the polymer is well swollen and the apparent molecular volume increases, when k is close to 1, the compatible polymer chains hardly swell, the compatible polymer becomes localized at the center of the microphase, and k becomes If it is extremely larger than 1, the block polymer and the compatible polymer will macroscopically phase separate. Therefore, in order to obtain the crosslinked elastomer composition of the present invention, it is necessary to select the value of k to 1.5 or less, more preferably 0.05 to 1.0. If the value of k is less than 0.05, the compatibilized polymer may not only be compatible with the block portion of the block polymer but also with the incompatible block portion (plasticizer). ), Temperature control becomes impossible. On the other hand, if the value of k is 2.5
In the above case, the molecular weight of the compatibilized polymer increases,
Workability may be difficult. Therefore, this k is set to 0.
It is necessary to select such that 05 ≦ k ≦ 2.5, and by changing k in this range, it is possible to obtain a crosslinked elastomer having the same viscoelasticity but different temperature dependence even though the polymer composition has the same composition. Can be.

In order to obtain a continuous structure elastomer according to the present invention, it is necessary to select the value of k from 0.05 ≦ k ≦ 0.35, more preferably from 0.05 to 0.2. . If the value of k is less than 0.05, the compatibilized polymer may not only be compatible with the compatible block portion of the block polymer but also with the incompatible block portion. (Cylinder structure or lamella structure) does not result in an elastomer composition and does not exhibit desired anisotropy. On the other hand, when the value of k exceeds 0.35, the desired anisotropy is not exhibited because a continuous structure is not formed. Furthermore, the modulus at 100% elongation of the compatibilized polymer must be at least 5 times that of the block polymer. When the modulus at 100% elongation is 5 times or less, the morphology of the elastomer composition shows a continuous structure, but does not show anisotropy due to a small difference in modulus between the block polymer and the compatibilized polymer. Therefore, in order to obtain a continuous structure elastomer composition having the desired anisotropic properties,
When ≤k≤0.35, the modulus of the compatibilized polymer at 100% elongation must be selected to be at least 5 times that of the block polymer. Also, by changing k in this range, it is possible to change the degree of anisotropic characteristics.

The block polymer composed of two types of incompatible polymer chains A and B used in the present invention includes AB type diblock polymer or ABA type triblock polymer, The types of the polymer chains A and B and the compatible polymer are not particularly limited. The polymer chain A or B is, for example, polystyrene, poly-α-methylstyrene, polymethacrylate, poly-2.
-Vinyl pyridine, polyisoprene, polyisobutylene, polybutadiene, styrene-butadiene copolymer,
It is formed from mutually incompatible components selected from styrene-isobutylene copolymer, styrene-isoprene-butadiene copolymer, polyethylene propylene, polyethylene butene, polydimethylsiloxane, polyethylene oxide and the like.

As the compatible polymer used in the present invention, a plurality of compatible polymers can be used as long as the polymer is compatible with the polymer chain A or B of the block polymer. It is also possible to add other optional third polymer components.

The crosslinked elastomer composition and the continuous structure elastomer composition of the present invention are prepared by adding a predetermined amount of a predetermined compatible polymer to the predetermined block polymer, melt-kneading the same, and further using a cross-linking agent and a cross-linking auxiliary agent. It can be produced by adding various additives and vulcanizing. In addition, the crosslinked elastomer composition contains a reinforcing agent, a filler, a softener, a plasticizer, an antioxidant, a processing aid, which are generally blended with the elastomer to improve the dispersibility and heat resistance of the elastomer. A compounding agent such as a coloring agent and a coloring material can be arbitrarily added in a necessary amount.

[0017]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but it goes without saying that the present invention is not limited to the following Examples.

Example 1 The following (a) block polymer (IR- (b) -SBR)
And (b) three types of compatible polymers (B
R: butadiene rubber) (where (a) the polymer chain SBR of the block copolymer and the BR of (b) are compatible) to prepare a test sample of the present invention by the following method. Polymer used in Example 1 (a) Block polymer: IR- (b) -SBR isoprene part 1,4 bond = 93% by weight 5: 5 SBR part ST / VN = 20% by weight / 53 mol% Mw = 5. 7 × 10 ⁵ Mn = 4.6 × 10 ⁵

[Table 1]

Preparation of Test Sample The block polymer, the compatible polymer, or the block polymer and the compatible polymer were kneaded with an 8-inch open roll for 3 to 5 minutes. Thereafter, 1.5 phr of sulfur, 3 phr of zinc stearate, and 0.7 phr of a vulcanization accelerator NS (Nt-butyl-2-benzothiazylsulfenamide) were added to the polymer and kneaded for 2 minutes. Next, this composition was press-vulcanized at 160 ° C. for 20 minutes in a mold of 15 × 15 × 0.2 cm to obtain samples for microscope and viscoelasticity test as shown in Table 2.

[0020]

[Table 2]

Using test samples a and C, electron micrographs were obtained in the following manner. The results are shown in FIGS. The results of tan δ for each sample are shown in FIG.
It is shown in FIG. Preparation of Electron Microscope Photographs The test sample obtained as described above was formed into an ultra-thin section of about 50 nm by a cryo-method using liquid nitrogen and stained with osmium tetroxide to obtain a sample for an electron microscope. Using a tan δ test viscoelastic spectrometer (manufactured by Toyo Seiki Seisaku-sho, Ltd.) at a predetermined temperature of −130 ° C. to 100 ° C. under the conditions of amplitude ± 2%, frequency 20 Hz, and static strain 10% using a 5 mm wide sample. tan δ was measured.

When FIGS. 1 and 2 (electron micrographs) are compared, the following is observed. FIG. 1 shows a striped structure derived from a block polymer. FIG. 2 in which a compatible polymer is added thereto shows a striped structure, but shows a structure in which the interval between the stripes is widened. This is because the compatible polymer was microscopically compatible with the compatible block portion of the block polymer, and caused the block polymer to swell.

FIGS. 3 and 4 show the experimental results of tan δ.
According to this, the following is understood. In FIG. 3, butadiene rubbers having different molecular weights show a tan δ peak at almost the same temperature. When these butadiene rubbers are added to the block polymer, as shown in FIG. 4, the butadiene rubber has different compatibility with the SBR portion in the block polymer due to the difference in molecular weight, and as a result, shows various tan δ curves, Dependencies can be changed.

Examples 2 and 3 and Comparative Examples The following (a) block polymer SI (styrene-isoprene block polymer) and (b) two compatible polymers PS-L and PS-M (PS: polystyrene) having different molecular weights ) (Where (a) the polymer chain S of the block polymer: styrene and PS of (b) are compatible) to prepare a test sample of the present invention by the following method. Raw materials used (a) Block polymer: SI (styrene-isoprene block polymer) Styrene content; 15% by weight Molecular weight of styrene part; 2.2 × 10 ⁴ (b) Compatible polymer: PS-L (low molecular weight polystyrene) molecular weight; 3.1 × 10 ³ : PS-M (medium molecular weight polystyrene) Molecular weight: 8.7 × 10 ³ Zinc stearate: zinc stearate (manufactured by Seido Chemical Co., Ltd.) Sulfur: oil-treated sulfur (Karuizawa Smelting Co., Ltd. Vulcanization accelerator: Noxeller NS (Nt-butyl-2-benzothiazolyl-sulfenamide (Ouchi Shinko Chemical Co., Ltd.))

Preparation of Test Samples The block polymer and the compatible polymer were kneaded in a pressure kneader (500 cc) for 3 to 5 minutes. Thereafter, zinc stearate, sulfur and a vulcanization accelerator were added and kneaded for 2 minutes. Further, the sheet was discharged from a pressure kneader and rolled into a sheet by a 6-inch roll. Next, this composition was added to 15 × 1
Press vulcanization was performed in a 5 × 0.2 cm mold at 160 ° C. for 20 minutes to obtain samples for a tensile test and a viscoelasticity test.

Using these test samples, a tensile test and a viscoelasticity test were performed according to the following test methods, and the results are shown in Table 3. According to the tensile test JIS K 6301, the modulus (M100) at 100% elongation, the breaking strength, and the breaking elongation were measured. Viscoelasticity test Using a viscoelasticity spectrometer (manufactured by Toyo Seiki Seisaku-sho, Ltd.), an amplitude of ± 2%, a frequency of 20 Hz, and a sample of 5 cm width were used.
El at −20, 0, and 20 ° C. was measured under the condition of a static strain of 10%.

[0027]

[Table 3] * Molecular weight ratio k The ratio of the weight average molecular weight of the compatible polymer to the weight average molecular weight of the block compatible with the compatible polymer in the block polymer was defined as the molecular weight ratio k.

FIGS. 5 and 6 show electron micrographs of the test samples of Example 2 and Comparative Example 3. FIG.

According to the results shown in Table 3 above, in the case of the comparative example which does not satisfy the molecular weight ratio k according to the present invention, the respective physical property values in the grain direction and the anti-grain direction are substantially the same, indicating anisotropy. On the other hand, in Examples 2 and 3 satisfying the molecular weight ratio k of the present invention, each physical property value was larger than that of Comparative Example, and also larger in the grain and anti-grain directions. It can be seen that they are different and therefore exhibit anisotropy. Looking at this in terms of molecular morphology (see FIG. 5),
It can be understood that the elastomer composition of the present invention has a continuous structure (cylinder structure or lamella structure).

[0030]

As described above, according to the present invention,
As a rubber material, a cross-linked elastomer composition in which the temperature dependency of viscoelastic properties is changed can be obtained by blending kneading compatible polymer components of the same composition having different molecular weights only with the same block polymer. By selecting a combination of a block polymer and its compatible polymer such that the ratio k becomes a predetermined value and kneading the mixture, an elastomer composition having a continuous structure having anisotropy can be obtained.

[Brief description of the drawings]

FIG. 1: Block polymer IR- (b) of a control sample
-Micrographs showing the morphology of SBR (× 20,
000).

FIG. 2 shows BR to sample IR- (b) -SBR of the present invention.
It is a micrograph (x20,000) which shows the morphology of the crosslinked elastomer which made L compatible.

FIG. 3 shows IR- (b) -SBR, BR- of a control sample.
H, each of tan in BR-M and BR-L
FIG. 6 is a diagram showing the temperature dependence of δ.

FIG. 4 shows IR-SBR / BR-H and IR-SB of the present invention.
Tan of R / BR-M and IR-SBR / BR-L
FIG. 6 is a diagram showing the temperature dependence of δ.

FIG. 5: Sample SI / PS-L of the present invention = 80/20
3 is a micrograph (× 20,000) showing the morphology of the compatible crosslinked elastomer of Example 1.

FIG. 6 is a micrograph (× 20,000) showing the morphology of a compatible crosslinked elastomer of control sample SI / PS-M = 80/20.

Claims (8)

[Claims] 1. A blend of (a) a block polymer having two or more incompatible blocks of two different compositions of A and B with (b) a polymer compatible only with a block of one composition. And an at least partially crosslinked elastomer composition. 2. The ratio (k) of the weight average molecular weight of the polymer (b) to the weight average molecular weight of a block compatible with the polymer (b) in the block polymer (a) is 1.5 or less. A crosslinked elastomer composition as described in the above. 3. The crosslinked elastomer composition according to claim 1, wherein the temperature dependence of viscoelasticity is controlled by changing k in the range of 0.05 ≦ k ≦ 2.5. 4. A blend of (a) a block polymer having two or more incompatible blocks having two different compositions of A and B with (b) a polymer compatible only with a block of one composition. And an elastomer composition having a continuous structure as a whole. 5. The ratio k between the weight average molecular weight of the polymer (b) and the weight average molecular weight of a block compatible with the polymer (b) in the block polymer (a) is 0.05 ≦.
5. The continuous structure elastomer composition according to claim 4, wherein k ≦ 0.35. 6. The continuous structure elastomer composition according to claim 4, wherein the (a) block polymer is a thermoplastic elastomer. 7. The continuous structure elastomer composition according to claim 4, wherein the (a) block polymer and / or (b) polymer is a crosslinkable elastomer. 8. The continuous structure elastomer composition according to claim 4, wherein at least a part of either the (a) block polymer or the (b) polymer is crosslinked.