rubber composition

Abstract

To provide a novel rubber composition that is excellent in damping performance in a wide temperature range and is also useful as a damping rubber composition.SOLUTION: There is provided, a rubber composition that contains at least a C5-dicyclopentadiene copolymer resin (B) by 20 to 105 pts.wt. and an inorganic filler by 20 to 200 pts.wt. for 100 pts.wt. of a nonpolar diene-based rubber.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a novel rubber composition containing at least a specific amount of C5-dicyclopentadiene (hereinafter sometimes referred to as DCPD) copolymer resin and a specific amount of an inorganic filler for non-polar diene rubber, and particularly relates to a novel rubber composition useful as a vibration damping rubber composition capable of exhibiting excellent vibration damping performance in a wide temperature range, and a vibration damping material made therefrom.

Background Art

[0002] Conventionally, vibration damping rubbers have been used in fields such as automobiles, railway vehicles, and housing equipment to prevent unnecessary vibrations from occurring.

[0003] In the automotive field, it is used as a mount material for suppressing vibrations from the engine. In response to the recent trend of higher efficiency, engines, exhaust pipes, etc. generate more heat, and vibration damping performance at high temperatures is also required for these.

[0004] To satisfy these requirements, there are compositions consisting of butyl rubber, a tackifier made of terpene resin and C5 fraction aliphatic petroleum resin, an adhesion-enhancing tackifier made of two polybutene resins with different molecular weights, and a fibrous component made of organic fibers and glass fibers (see, for example, Patent Document 1), as well as a vibration-damping rubber that can be used over a wide temperature range, which is made by blending at least one selected from terpene resin, C5 petroleum resin, or fully hydrogenated petroleum resin with a thermoplastic elastomer made of isobutylene-isoprene copolymer and polystyrene-vinyl polyisoprene block copolymer. Examples of proposed rubber compositions include one in which coumaron resin is blended with at least one polymer having rubber elasticity selected from natural rubber, functionalized natural rubber, or modified natural rubber (see, for example, Patent Document 2), and another in which rubber compositions exhibiting excellent vibration damping and shock absorption performance at temperatures from 10°C to 50°C are blended with butyl rubber, and another in which an aliphatic monomer polymerization resin having at least 30 wt% aromatic monomer residues, or an aromatic monomer polymerization resin having 70 wt% or more aromatic monomer residues are blended with butyl rubber, and a rubber composition exhibiting excellent vibration damping performance in high-temperature regions above 50°C is also proposed (see, for example, Patent Document 4). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 5815176 [Patent Document 2] Japanese Patent Publication No. 2010-254923 [Patent Document 3] Japanese Patent Publication No. 2012-153834 [Patent Document 4] Japanese Patent Publication No. 2021-50302 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, none of the compositions proposed in Patent Documents 1 to 4 have achieved stable vibration damping performance across a wide temperature range in increasingly demanding operating environments in recent years, and there is a particular need for a material that can exhibit vibration damping performance over a wide temperature range. Therefore, the present invention aims to solve the above problems and provide a novel rubber composition that is excellent in vibration damping performance over a wide temperature range and is also useful as a vibration-damping rubber composition. [Means for solving the problem]

[0007] In order to solve the above problems, the inventors conducted diligent research and found that by blending a non-polar diene rubber with at least a specific amount of C5-DCPD copolymer resin and a specific amount of inorganic filler, a novel rubber composition is obtained that exhibits excellent vibration damping performance over a wide temperature range and is also useful as a vibration-damping rubber composition, thus completing the present invention.

[0008] In other words, the present invention relates to a rubber composition characterized by containing at least 20 to 105 parts by weight of C5-DCPD copolymer resin and 20 to 200 parts by weight of inorganic filler per 100 parts by weight of non-polar diene rubber.

[0009] The present invention will be described in detail below.

[0010] The rubber composition of the present invention is a novel rubber composition comprising at least 20 to 105 parts by weight of C5-DCPD copolymer resin and 20 to 200 parts by weight of inorganic filler per 100 parts by weight of non-polar diene rubber, and may further contain a softening agent or the like.

[0011] The nonpolar diene rubber constituting the rubber composition of the present invention is not limited as long as it belongs to the category of nonpolar diene rubber having a carbon-carbon double bond. Examples include natural rubber (sometimes denoted as NR), polyisoprene rubber (sometimes denoted as IR), polybutadiene rubber (sometimes denoted as BR), ethylene-propylene-diene rubber (sometimes denoted as EPDM), and butyl rubber (sometimes denoted as IIR). In particular, IR, BR, EPDM, and IIR are preferred because they result in a vibration-damping rubber composition with excellent vibration damping performance due to their excellent compatibility with C5-DCPD copolymer resin. These may be used individually or in combination. The molecular weight and microstructure of the nonpolar diene rubber are not particularly limited and may be end-modified with amine, amide, silyl, alkoxysilyl, carboxyl, hydroxyl groups, etc., or may be epoxidized, chlorinated, or brominated. Commercially available products can be used. In this case, if a rubber other than a non-polar diene rubber is used, the resulting composition will have problems with compatibility with the C5-DCPD copolymer resin and dispersibility of the inorganic filler, making it difficult to achieve vibration damping performance, especially vibration damping performance over a wide temperature range.

[0012] The C5-DCPD copolymer resin constituting the rubber composition of the present invention is a resin obtained by copolymerizing a C5 fraction (sometimes referred to as an aliphatic component fraction), which is a fraction with a boiling point range of 20 to 110°C obtained by the thermal decomposition of petroleum products, with DCPD, which is a dicyclopentadiene. In this case, the C5 fraction can be a fraction with a boiling point range of 20 to 110°C, and the components of the C5 fraction include, for example, C4 aliphatic compounds such as butene, butadiene, and isobutene; C5 chain aliphatic compounds such as 2-methyl-1-butene, 3-methyl-1-butene, 2-methyl-2-butene, and piperylene; and 1-hexene, 2-hexene, 3-hexene, 2-methyl-1-pentene, and 3-methyl-1-pentene. Examples include C6 chain aliphatic compounds such as 4-methyl-1-pentene, 2-methyl-2-pentene, 3-methyl-2-pentene, 4-methyl-2-pentene, 2-ethyl-1-butene, and 2,3-dimethyl-1-butene; and C7 chain aliphatic compounds such as 1-heptene, 2-heptene, 3-heptene, 2-methyl-3-hexene, 4-methyl-2-hexene, and 3,4-dimethyl-2-pentene. Furthermore, DCPD may be dicyclopentadiene alone, or a dicyclopentadiene fraction which is a pyrolysis fraction of petroleum products, and may include, for example, methyldicyclopentadiene, dimethyldicyclopentadiene, cyclopentadiene, and methylcyclopentadiene.

[0013] The C5-DCPD copolymer resin does not exclude the inclusion of C9 components in a range that does not affect the copolymerization as long as the objectives of the present invention are achieved. However, when it is intended to exhibit a modification effect on non-polar diene rubber, particularly vibration damping performance, it is preferable that it does not contain C9 fractions (sometimes referred to as aromatic component fractions) which are fractions in the decomposition fractions of petroleum products with a boiling point range of 140 to 280°C.

[0014] As a method for producing the C5-DCPD copolymer resin, any method that enables the production of the C5-DCPD copolymer resin may be used. For example, a method can be used in which a polymerization reaction is carried out using a polymerization catalyst with a C5 fraction, DCPD, and a saturated hydrocarbon of the C5 fraction such as n-pentane as a solvent. The polymerization catalyst in this case is not particularly limited, and examples include aluminum trichloride, aluminum tribromide, boron trifluoride, or complexes thereof. Among these, complexes of boron trifluoride with methanol, propanol, butanol, isobutanol, isopentanol, or other alcohols or phenols are selected due to their excellent catalytic activity. Among these, complexes with butanol, isobutanol, or isopentanol are more preferred. The complex may be used as is or prepared in-suit immediately before use from boron trifluoride and alcohols or phenols. Furthermore, as the raw material oil, it is preferable to use a mixture of 25-70% by weight of C5 fraction and 75-30% by weight of DCPD fraction, as this yields a C5-DCPD copolymer resin with particularly excellent softening point and color. Furthermore, there are no particular restrictions on the polymerization temperature, but 20-80°C is preferred, and 30-60°C is particularly preferred, as this results in high polymerization activity and excellent productivity. The amount of polymerization catalyst and polymerization time can be appropriately selected depending on the temperature and the water concentration in the raw material oil, and typically, for example, 0.1-2.0% by weight of polymerization catalyst relative to the raw material oil and a polymerization time of 0.1-10 hours are preferred. There are no particular restrictions on the reaction pressure, but atmospheric pressure to 1 MPa is preferred. There are no particular restrictions on the atmosphere, but a nitrogen atmosphere is preferred.

[0015] Furthermore, since the C5-DCPD copolymer resin is a rubber composition that exhibits particularly excellent vibration damping over a wide temperature range, it is preferable that the double bond hydrogen area in the peak area measured by a proton nuclear magnetic resonance spectrometer is 6 to 13%, and more preferably 8 to 11%. The proton nuclear magnetic resonance spectrum in this case can be measured, for example, using a 400 MHz proton nuclear magnetic resonance spectrometer.

[0016] Furthermore, the olefinic double bond / dicyclopetanediene residue double bond (area ratio) in the proton nuclear magnetic resonance spectrum is preferably 30 / 70 to 75 / 25, and more preferably 40 / 60 to 60 / 40. The weight-average molecular weight, measured by gel permeation chromatography in accordance with JIS K-0124 (2011) using standard polystyrene as the standard substance, is preferably 1500 to 2500, and more preferably in the range of 1800 to 2100. The weight-average molecular weight / number-average molecular weight ratio is preferably 1.5 to 2.5, and more preferably 1.7 to 2.2. Furthermore, the bromine value, measured in accordance with JIS K-2605 (1996), is preferably 40 to 55 (g-Br2 / 100g), and the softening point, measured in accordance with JIS K-2207 (1996) (ring-sphere method), is preferably 80 to 125°C.

[0017] Furthermore, since it results in a rubber composition with excellent appearance, it is preferable that the hue (Gardner hue) measured in accordance with ASTM D-1544-63T for a 50% by weight toluene solution is between 4 and 9.

[0018] The rubber composition of the present invention contains 20 to 105 parts by weight of C5-DCPD copolymer resin per 100 parts by weight of non-polar diene rubber. Here, if the amount of C5-DCPD copolymer resin is less than 20 parts by weight, the resulting composition will have poor vibration damping performance at high temperatures, while if the amount of C5-DCPD copolymer resin exceeds 105 parts by weight, the resulting composition will have poor vibration damping performance at low temperatures.

[0019] Examples of the inorganic filler constituting the rubber composition of the present invention include those generally blended with rubber, such as carbon black, calcium carbonate, talc, clay, mica, alumina, aluminum hydroxide, potassium titanate, boron nitride, vermiculite, and the like. These inorganic fillers may be used alone or in combination of two or more. The rubber composition of the present invention contains 20 to 200 parts by weight of an inorganic filler based on 100 parts by weight of the non-polar diene rubber. Here, when the amount of the inorganic filler is less than 20 parts by weight, the resulting composition is inferior in vibration damping performance at high temperatures. On the other hand, when the amount of the inorganic filler exceeds 200 parts by weight, the resulting rubber composition is inferior in vibration damping performance at low temperatures.

[0020] And, particularly, since it exhibits stable vibration damping performance from a low temperature state to a high temperature state, it is preferable that the inorganic filler includes at least one selected from a layered inorganic filler, a plate-like inorganic filler, and a fibrous inorganic filler, and the amount thereof is preferably 3 to 40 parts by weight based on 100 parts by weight of the non-polar diene rubber. Examples of the layered inorganic filler include mica, boron nitride, etc., examples of the plate-like inorganic filler include clay, vermiculite, etc., and examples of the fibrous inorganic filler include alumina, potassium titanate, etc.

[0021] In the rubber composition of the present invention, further, compounding agents usually used in the rubber industry, such as crosslinking agents, crosslinking accelerators, softeners, foaming agents, scorch agents, processing aids, anti-aging agents, zinc oxide, magnesium oxide, stearic acid, etc. can be appropriately selected and used within the range of normal compounding amounts.

[0022] And, the rubber composition of the present invention can be obtained by blending the above non-polar diene rubber, C5-DCPD copolymer resin, inorganic filler, and various compounding agents appropriately selected as needed, and using a mixing method such as a Banbury mixer, a pressure kneader, an open roll. [[ID=ed=14]]

Advantages of the Invention

[0023] According to the present invention, by blending a specific amount of a C5-DCPD copolymer resin and an inorganic filler with a non-polar diene rubber, it becomes possible to provide a rubber composition that is expected to be useful as a vibration damping material exhibiting excellent vibration damping performance in a wide temperature range.

Examples

[0024] The present invention will be described below with reference to examples, but the present invention is not limited by these examples. The analysis and test methods used in the examples and comparative examples are as follows.

[0025] The raw materials of the rubber composition are shown below.

[0026] <Non-polar diene rubber> Butyl rubber: manufactured by JSR Corporation, (trade name) BUTYL268.

[0027] <Inorganic filler> Calcium carbonate: manufactured by Maruo Calcium Co., Ltd., heavy calcium carbonate. Mica: manufactured by Yamaguchi Mica Co., Ltd., (trade name) A-21S. Carbon black: manufactured by Asahi Carbon Co., Ltd., (trade name) Asahi #70.

[0028] <Compound> Process oil: manufactured by Idemitsu Kosan Co., Ltd., (trade name) Diana Process Oil AH-16.

[0029] The analysis method of the C5-DCPD copolymer resin is shown below.

[0030] ~Proton NMR (nuclear magnetic resonance spectrum) measurement~ The C5-DCPD copolymer resin was dissolved in chloroform-d (manufactured by Wako Pure Chemical Industries, Ltd.) and measured by a normal NMR measurement method. For the obtained spectrum, the area ratio was determined based on the following calculation formula. Double bond hydrogen area (%) = (double bond hydrogen peak area) / (total of all peak areas) × 100 Olefin-type double bond (area ratio) = (Olefin-type double bond hydrogen peak area) / (Sum of double bond hydrogen peak areas of olefinic and DCPD residues) × 100 DCPD residue double bond (area ratio) = (DCPD double bond hydrogen peak area) / (sum of olefinic, DCPD residue double bond hydrogen peak areas) × 100 The peaks are as follows: Double bond hydrogen peak: 4.4~6.3 ppm. Olefin double bond peak: 4.4-5.2 ppm. DCPD residue double binding peak: 5.3–5.5 ppm.

[0031] ~Number average molecular weight (Mn), weight average molecular weight (Mw) measurement~ Polystyrene was used as the standard substance, and the measurement was performed by gel permeation chromatography in accordance with JIS K-0124 (2011).

[0032] ~Bromine value measurement~ Measured according to the method compliant with JIS K-2605 (1996). ~Softening point measurement~ Measurements were taken using a method compliant with JIS K-2207 (1996) (ring-sphere method).

[0033] ~Vibration damping~ A viscoelasticity measuring device (manufactured by UBM, product name Rheogel E-4000) was used to measure the loss tangent tanδ at a frequency of 10 Hz. The values ​​at 20°C, 40°C, 60°C, and 80°C were used as indicators of vibration damping performance. A larger value indicates better vibration damping performance, and a value of 0.18 or higher between 20°C and 80°C was considered to indicate excellent vibration damping.

[0034] ~Temperature dependence of vibration damping~ The temperature dependence of the damping performance was determined by dividing the loss tangent at the temperature with the highest loss tangent by the loss tangent at the temperature with the lowest loss tangent. A value in the range of 1.0 to 2.0 was considered to indicate excellent temperature dependence.

[0035] Synthesis Example 1 A 2-liter glass autoclave was charged with a feedstock oil consisting of 55% by weight of C5 fraction and 45% by weight of DCPD fraction, obtained by the decomposition of naphtha. Next, the autoclave was adjusted to 40°C under a nitrogen atmosphere, and 1.4 parts by weight of boron trifluoride isobutanol complex was added as a Friedel-Crafts type catalyst per 100 parts by weight of the feedstock oil, and polymerization was carried out for 2 hours. After that, the catalyst was removed with an aqueous solution of caustic soda, and the unreacted oil in the oil phase was distilled to obtain a C5-DCPD copolymer resin (sometimes referred to as resin A). The evaluation results are shown in Table 1.

[0036] Synthesis Examples 2-8 C5-DCPD copolymer resins (hereinafter sometimes referred to as resins B to H) were obtained by the same method as in Example 1, except that the weight ratio of the raw material oil, consisting of C5 fraction and DCPD fraction obtained by the decomposition of naphtha, was as shown in Tables 1 and 2. The evaluation results are shown in Tables 1 and 2.

[0037] [Table 1]

[0038] [Table 2]

[0039] Example 1 As a diene-based rubber, 100 parts by weight of butyl rubber was mixed with 60 parts by weight of resin A, 70 parts by weight of calcium carbonate, 20 parts by weight of mica, 10 parts by weight of carbon black, and 30 parts by weight of process oil in a Banbury mixer (manufactured by Toyo Seiki, product name BR600). The resulting mixture was sheeted using an 8-inch roll to form a rubber composition, and a viscoelasticity test (vibration damping test) was performed. The results are shown in Table 3. The obtained rubber composition showed excellent vibration damping properties and temperature dependence.

[0040] Examples 2-12 Except for the rubber composition formulation shown in Tables 3 and 4, the rubber composition was prepared and evaluated in the same manner as in Example 1. The results are shown in Tables 3 and 4.

[0041] The resulting rubber composition exhibited excellent vibration damping properties and temperature dependence.

[0042] [Table 3]

[0043] [Table 4]

[0044] Comparative Examples 1-4 The compositions were prepared and evaluated in the same manner as in Example 1, except that the compositional formulation was as shown in Table 5. The results are shown in Table 5.

[0045] Comparative Example 5 The compositions were prepared and evaluated in the same manner as in Example 1, except that a C5-based hydrocarbon resin ((product name) T-REZ RA100, manufactured by ENEOS Corporation; sometimes referred to as resin I) was used instead of resin A. The results are shown in Table 5.

[0046] [Table 5] [Industrial applicability]

[0047] The novel rubber composition of the present invention is a vibration-damping rubber composition that exhibits excellent vibration damping performance over a wide temperature range, and can be suitably used in products and components in fields where vibration damping is required.

Claims

1. A vibration damping material characterized by comprising a rubber composition containing at least 20 to 105 parts by weight of C5-dicyclopentadiene copolymer resin and 20 to 200 parts by weight of inorganic filler per 100 parts by weight of nonpolar diene rubber, wherein the C5-dicyclopentadiene copolymer is a binary copolymer of a C5 fraction and a dicyclopentadiene fraction obtained by thermal decomposition of petroleum products.

2. The vibration damping material according to claim 1, characterized in that the non-polar diene rubber is at least one selected from the group consisting of polyisoprene rubber, polybutadiene rubber, ethylene-propylene-diene rubber, and butyl rubber.

3. The vibration damping material according to claim 1 or 2, characterized in that the C5-dicyclopentadiene copolymer resin is a C5-dicyclopentadiene copolymer resin that satisfies any of the following characteristics (1) to (5). (1) The double bond hydrogen area in the peak area measured by a proton nuclear magnetic resonance spectrometer was 6-13%, and the olefinic double bond / dicyclopentadiene residue double bond (area ratio) was 30 / 70-75 / 25. (2) Standard polystyrene is used as the standard material, and the weight-average molecular weight measured by gel permeation chromatography in accordance with JIS K-0124 (2011) is 1200 to 2500, and the weight-average molecular weight / number-average molecular weight is 1.5 to 2.

5. (3) Bromine value measured in accordance with JIS K-2605 (1996) is 40 to 55 (g-Br ２ ( / 100g). (4) The softening point measured in accordance with JIS K-2207 (1996) (ring-sphere method) was 80 to 125°C. (5) As a 50 wt% toluene solution, the Gardner hue measured in accordance with ASTM D-1544-63T is 4 to 9.

4. The vibration damping material according to any one of claims 1 to 3, characterized in that the inorganic filler is at least one selected from the group consisting of carbon black, calcium carbonate, talc, clay, mica, alumina, aluminum hydroxide, vermiculite, potassium titanate, and boron nitride.

5. The vibration damping material according to any one of claims 1 to 4, characterized in that the inorganic filler comprises at least 3 to 40 parts by weight of a filler selected from layered inorganic fillers, plate-shaped inorganic fillers, and fibrous inorganic fillers per 100 parts by weight of nonpolar rubber.

6. The vibration damping material according to claim 5, characterized in that the layered inorganic filler is mica and / or boron nitride, the plate-like inorganic filler is clay and / or vermiculite, and the fibrous inorganic filler is alumina and / or potassium titanate.

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