JP2012153834A - Rubber composition, method for manufacturing rubber composition, and rubber component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition, a method for manufacturing the rubber composition, and a rubber component, which show high damping performance and impact absorption performance even in a high temperature region.SOLUTION: The rubber composition contains 10 parts by mass or more of a coumarone resin based on 100 parts by mass of a polymer with rubber elasticity. It is desirable that a contained amount of the coumarone resin is 20 parts by mass or more. It is desirable that the polymer with rubber elasticity is natural rubber, modified natural rubber, or functionalizing natural rubber, and the epoxidized natural rubber is particularly desirable. The rubber component is obtained by using the rubber composition which contains 10 parts by mass or more of the coumarone resin based on 100 parts by mass of the polymer with rubber elasticity.

Description

  The present invention relates to a rubber composition, a method for producing the rubber composition, and a rubber part.

  Rubber parts are widely used as vibration damping members for various machines, soundproof members for buildings, shock absorbing members, and the like. The vibration damping, soundproofing, and shock absorbing performances of rubber are all exhibited by converting mechanical energy such as vibration and impact into molecular motion, that is, thermal energy by rubber-specific properties and viscosity called rubber elasticity.

  Since rubber elasticity and viscosity change according to temperature, the speed and efficiency of converting mechanical energy into heat energy also change according to temperature. For this reason, even rubber parts that exhibit excellent vibration damping performance in a certain temperature range may not exhibit sufficient vibration damping performance in other temperature ranges.

  In Patent Document 1, 0.1 to 30 parts by weight of an aliphatic polyester resin having a glass transition temperature of 0 ° C. or more and 10 to 80 parts by weight of an inorganic filler having a silanol group with respect to 100 parts by weight of a crosslinkable polymer component. A method for producing a crosslinked polymer composition is disclosed in which a polymer composition containing 0.1 to 10 parts by weight of a metal compound and a crosslinking agent is crosslinked and then subjected to a heat treatment. According to this method, it is described that a crosslinkable polymer composition having excellent vibration damping properties, sound absorbing properties and shock absorbing properties in a wide temperature range can be obtained.

JP 2010-138371 A

  The method disclosed in Patent Document 1 is said to give a crosslinkable polymer composition having excellent vibration damping properties, sound absorbing properties and shock absorbing properties over a wide temperature range. The value of the sound absorption coefficient is a measured value at 20 ° C. or room temperature, and the results of evaluating these characteristics in a wide temperature range, particularly a high temperature range of 30 ° C. or higher are not described. Further, as described in the detailed description of the invention of the same document (particularly paragraph [0017]), in the method of Patent Document 1, “Tg is 0 ° C. or higher aliphatic polyester resin, inorganic filler having silanol group, If any of the metal compound and the cross-linking agent is added and further heat-treated after the cross-linking (primary cross-linking), if any condition is missing, excellent vibration damping, sound absorption and shock absorption It cannot be secured over a wide temperature range. " For this reason, there exists a problem that the filler to be used is limited. Furthermore, since heat treatment must be performed after the primary crosslinking, there are also disadvantages in terms of productivity and cost.

  The present invention has been made in view of the above problems, and includes a rubber composition exhibiting high vibration damping performance and shock absorption performance in a higher temperature range than a conventionally known rubber composition, a method for producing the rubber composition, and a rubber part. The purpose is to provide.

  As a result of intensive studies, the present inventors generally incorporated a small amount of coumarone resin, which is generally blended as a natural rubber or synthetic rubber adhesion improver or tackifier, in excess of the amount normally used. The present invention has been completed by discovering that high vibration damping and shock absorption can be exhibited in a temperature range higher than that of the vibration rubber and that the temperature range can be arbitrarily set.

  That is, the rubber composition according to the first aspect of the present invention contains 10 parts by mass or more of coumarone resin with respect to 100 parts by mass of the polymer having rubber elasticity. More preferably, 20 parts by mass or more of coumarone resin is contained with respect to 100 parts by mass of the polymer having rubber elasticity. The polymer having rubber elasticity is preferably natural rubber, modified natural rubber or functionalized natural rubber. Of these, functionalized natural rubber is more preferable, and epoxidized natural rubber is particularly preferable.

  The rubber component according to the second aspect of the present invention is obtained using the rubber composition according to the first aspect of the present invention.

The method for producing a rubber composition according to the third aspect of the present invention is as follows. In the production of a rubber composition used at a predetermined temperature, 100 parts by mass of natural rubber, modified natural rubber, or functionalized natural rubber is described below. Blending the amount of coumarone resin determined by the formula.
Blending amount of coumarone resin (parts by mass) = (predetermined temperature (° C.) − 1.91) /0.356

  The rubber component according to the fourth aspect of the present invention is obtained using the rubber composition manufactured by the method according to the third aspect of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the rubber composition which shows high damping performance and shock absorption performance in a temperature range higher than a conventionally known rubber composition, the manufacturing method of a rubber composition, and a rubber component can be provided.

It is the figure which showed the temperature dependence of the hardness of the rubber composition which concerns on this invention as a graph. It is the figure which showed the measurement result of the loss tangent of the rubber composition which concerns on this invention as a graph. It is the figure which showed the temperature dependence of the impact resilience of the rubber composition which concerns on this invention as a graph. It is the figure which showed the temperature dependence of the impact absorption rate of the rubber composition which concerns on this invention as a graph. It is the figure which showed the relationship between the compounding quantity of a coumarone resin in the rubber composition which concerns on this invention, and the point where an impact absorption rate becomes the maximum as a graph.

  Hereinafter, embodiments of the present invention will be described. The rubber composition according to the embodiment of the present invention is obtained by blending a coumarone resin with 100 parts by mass of the base rubber.

  The base rubber is not particularly limited as long as it is a polymer having rubber elasticity, but a polymer that is partially or completely compatible with the coumarone resin is preferable. Natural rubber is preferable, functionalized natural rubber is more preferable, and epoxidized natural rubber is particularly preferable.

  The coumarone resin refers to a resin obtained by copolymerizing coumarone and other aromatic hydrocarbons such as indene and styrene. Commercially available are, for example, Knit Resin (registered trademark) Coumarone manufactured by Nikkiso Chemical Co., Ltd.

  In the composition according to the embodiment of the present invention, the coumarone resin is blended in an amount of 10 parts by mass or more based on 100 parts by mass of the base rubber. Preferably it is 10-200 mass parts, More preferably, it is 20-100 mass parts. When the blending amount of the coumarone resin is less than 10 parts by mass, the temperature range showing low resilience is lower than the temperature normally used as a shock absorbing material or a vibration damping material, and sufficient performance cannot be obtained. On the other hand, when the amount of the coumarone resin is larger than this, there is no effect on the impact absorbability, but the workability may be lowered because the adhesiveness of the composition is increased.

  In a conventionally known configuration, the coumarone resin is usually blended in an amount of 1 to 5 parts by mass with respect to 100 parts by mass of the base rubber as an adhesion improver or tackifier for rubber. On the other hand, the present inventors greatly improve vibration damping and shock absorption in a high temperature range by blending the coumarone resin at a high ratio of 10 parts by mass or more with respect to 100 parts by mass of the base rubber, By appropriately setting the blending ratio of base rubber and coumarone resin, it is possible to exhibit high vibration damping and shock absorption even at a higher temperature range than conventional vibration-damping rubber. And found that it can be set arbitrarily.

  The rubber composition according to the present invention can contain other auxiliary materials, additives, and the like that are usually used in the rubber composition within a range not departing from the object of the invention. For example, a filler, a reinforcing material, a crosslinking agent, a crosslinking aid, an antioxidant, an anti-aging agent, a processing aid and the like can be included.

  Examples of the filler or reinforcing material include silica, silica, diatomaceous earth and the like, oxides such as alumina, titanium oxide, calcium oxide, magnesium oxide, zinc oxide, iron oxide, and beryllium oxide, aluminum hydroxide, hydroxide Magnesium, calcium hydroxide, aluminate hydrate hydroxides, clay, talc, mica, asbestos, bentonite, zeolite, calcium silicate, montmorillonite and other silicates, calcium carbonate, magnesium carbonate, hydrotalcite Carbonate, sulfate sulfate, calcium sulfite, sulfate, barium sulfate, calcium sulfite, etc., molybdenum disulfide, potassium titanate, silicon carbide, linter, linen, sisal wood flour, silk, leather powder, collagen Examples thereof include fiber, viscose, and acetate.

  Examples of the crosslinking agent include sulfur-based crosslinking agents such as sulfur, sulfur dichloride and morpholine disulfide, and non-sulfur-based crosslinking agents such as organic peroxides and metal oxides.

  Examples of the crosslinking aid include thiuram compounds, thiazole compounds, sulfenamide compounds, sulfide compounds, thiourea compounds, and the like.

  Examples of the antioxidant include diphenylamine-based antioxidants such as dioctylated diphenylamine, and p-phenylenediamine-based antioxidants such as N, N′-diphenyl-p-phenylenediamine.

  Examples of the antioxidant include N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine (6PPD), N, N′-dinaphthyl-p-phenylenediamine (DNPD), and N-isopropyl. -N'-phenyl-p-phenylenediamine (IPPD), styrenated phenol (SP) and the like.

  Processing aids include, for example, plasticizers such as phthalate esters, diallyl phthalates, adipic acid esters, fatty acid esters, trimellitic acid esters, softeners such as fatty acids and tall oil, rosin, terpene resins, alkylphenol aldehyde condensation Examples include tackifiers such as body.

(Example)
EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated further in detail, this invention is not limited by a following example.

Example 1
(Preparation of rubber composition)
1,000 g of epoxidized natural rubber (epoxidation rate of about 50%) was put into a pressure kneader (DS3-7.5MWH-S type manufactured by Moriyama Co., Ltd.), and kneaded until the resin temperature reached 60 ° C. Here, 50 g of zinc oxide (manufactured by Inoue Lime Industry Co., Ltd., Meta Z L-40), 10 g of stearic acid, 40 g of calcium stearate, 10 g of anti-aging agent (manufactured by Ouchi Shinsei Chemical Co., Ltd., Sannock), polyethylene glycol 1 0.0 g was added and kneaded for about 2 minutes until the whole became uniform. Subsequently, 400 g of clay (aluminum silicate, Burgess Pigment Co., Burgess # 30), 300 g of polyvinyl chloride (ZEST P-21, Shin-Daiichi Vinyl Co., Ltd.), Coumarone resin (Nikko Chemical Co., Ltd., knit resin) 200 g of Coumarone G-90) and 150 g of DOP (bis- (2-ethylhexyl) phthalate) were added and kneaded for about 5 minutes until the whole became uniform. The resin temperature at the end of kneading was about 100 ° C. After completion of the kneading, the mixture was left until the resin temperature became 80 ° C. or lower. After the resin temperature becomes 80 ° C. or less, 5 g of sulfur (powder sulfur 200 mesh manufactured by Hosoi Chemical Co., Ltd.), 10 g of vulcanization accelerator CBS (Noxeller CZ manufactured by Ouchi Shinsei Chemical Co., Ltd.), vulcanization acceleration 10 g of the agent TMTD (Nouchira TT manufactured by Ouchi Shinsei Chemical Co., Ltd.), 3 g of silicone oil (SH-200 manufactured by Toray Industries, Inc.) and 10 g of chromium oxide (Green F3 manufactured by Nippon Kagaku Kogyo Co., Ltd.) are homogeneous throughout. It kneaded for about 2 minutes until it became. The obtained rubber composition was taken out and formed into a sheet shape with a roll (14-inch roll manufactured by Yamazaki Seisakusho Co., Ltd.). The formulation is shown in Table 1.

(Formation of sample for evaluation)
The obtained rubber composition sheet was cut into an appropriate size and set in a mold (external dimensions 240 × 160 × 30 mm, product dimensions 200 × 120 × 2 mm). The mold was set in a hydraulic molding machine (manufactured by Shoji Co., Ltd., output 70 t) set in advance at 150 ° C., and subjected to crosslinking molding by pressing for 10 minutes to obtain a rubber sheet for evaluation. Separately from this, a rubber ball for evaluation was produced using a spherical mold having a diameter of 30 mm.

(Evaluation of the physical properties)
Various physical properties of the obtained sample for evaluation were evaluated by the following methods.
(Tensile strength / elongation)
It measured according to JIS K6251. For the measurement, a desktop material testing machine STA-1225 manufactured by Orientec Co., Ltd. was used.
(Tear strength)
It measured according to JIS K6252. For the measurement, a desktop material testing machine STA-1225 manufactured by Orientec Co., Ltd. was used.
(hardness)
It measured according to JIS K6253. For the measurement, a rubber / plastic hardness meter KR-14 manufactured by Furusato Seiki Co., Ltd. was used.
(Loss tangent)
The measurement was performed using EXTAR DMS6100 manufactured by SII Nano Technology. The measurement was performed in a tensile mode, the frequency was 100 Hz, and the strain rate was 0.1%.
(Rebound resilience)
A rubber ball for evaluation was dropped from a height of 100 cm (reference height) onto an iron plate (150 × 150 × 20 mm), and the rebound height was measured. Bounce height / reference height × 100 = rebound resilience.
(Shock absorption rate)
An iron plate (150 × 150 × 20 mm) was fixed to a flat surface, and an evaluation rubber sheet was placed thereon. An iron ball (diameter 11 mm, weight 5.4 g) was dropped onto a rubber sheet for evaluation from a height of 100 cm (reference height), and the rebound height was measured. 100− (bounce height / reference height × 100) = shock absorption rate.
Table 2 shows the tensile strength, elongation, and tear strength, and Table 2 and Fig. 1 show the hardness. The loss tangent is shown in FIG. 2, the rebound resilience is shown in FIG. 3, and the shock absorption rate is shown in FIG.

(Examples 2 to 4)
Samples for evaluation were prepared by the same procedure as in Example 1 except that the types and mixing ratios of the raw materials were changed as shown in Table 1, and various physical properties were measured. Table 2 shows the tensile strength, elongation, and tear strength, and Table 2 and Fig. 1 show the hardness. The loss tangent is shown in FIG. 2, the rebound resilience is shown in FIG. 3, and the shock absorption rate is shown in FIG.

(Comparative example)
Samples for evaluation were prepared by the same procedure as in Example 1 except that the types and mixing ratios of the raw materials were changed as shown in Table 1, and various physical properties were measured. Table 2 shows the tensile strength, elongation, and tear strength, and Table 2 and Fig. 1 show the hardness. The loss tangent is shown in FIG. 2, the rebound resilience is shown in FIG. 3, and the shock absorption rate is shown in FIG.

  As shown in FIG. 1, the hardness of the rubber composition according to Examples 1 to 4 decreases as the temperature increases. When the blending ratio of coumarone resin increases, the ratio of hardness decrease due to temperature rise tends to increase, but the changes are all continuous and monotonous, and abrupt changes in hardness are observed in a specific temperature range. Absent. From this data, it is only expected that the hardness of the rubber composition decreases in a temperature range of about 30 ° C. or higher as the blending ratio of the coumarone resin increases, and the composition according to each example is specified. The fact that it exhibits particularly excellent shock absorption and vibration damping properties in the temperature range cannot be read.

  However, when FIG. 2 is referred, it turns out that the loss tangent of each rubber composition has a peak in a different temperature range by a comparative example and Examples 1-4, respectively. This means that the temperature range where the impact absorption performance is maximized changes depending on the blending amount of coumarone resin. That is, coumarone resin does not simply reduce the hardness of the rubber composition at high temperatures, but can impart high shock absorption and vibration damping properties at high temperatures by changing the viscoelastic properties of the rubber composition. It became clear.

  3 and 4 show the results of actual evaluation of the temperature dependence of the impact resilience and impact absorbability of the rubber compositions obtained in each example. Also from these results, it can be seen that the temperature at which the rebound rate is minimized varies depending on the blending amount of coumarone resin. When FIG. 4 is seen, while the comparative example shows a repulsion rate of about 22% regardless of the temperature, each of Examples 1 to 4 shows an extremely small value of 0 to 2%. Yes. This result shows that the temperature range where the rebound rate is minimized can be changed by adjusting the blending amount of coumarone resin, and at the same time, the decrease in the rebound rate is not simply due to the softening of the rubber composition. This is to prove that there is nothing.

  As described above, since the rubber composition according to the present invention has high impact absorbing performance and vibration damping performance, it is suitable for various rubber parts such as shock absorbers, vibration damping materials, and soundproofing materials. Here, the rubber part is not limited to one molded for a specific application. Basic rubber materials, such as sheets, spheres, cylinders, prisms, etc. that are cut and ground according to the application, are also included in the rubber parts here. Furthermore, a rubber part or a rubber material imparted with structural characteristics by a known method such as foamed rubber is also included in the rubber part referred to in the present invention.

The rubber composition according to the present invention can also be expressed as follows.
(Appendix 1)
A rubber composition containing 10 parts by mass or more of coumarone resin with respect to 100 parts by mass of a polymer having rubber elasticity.
(Appendix 2)
The rubber composition according to supplementary note 1, wherein the content of the coumarone resin is 20 parts by mass or more.
(Appendix 3)
The rubber composition according to appendix 1 or 2, wherein the polymer having rubber elasticity is natural rubber, modified natural rubber, or functionalized natural rubber.
(Appendix 4)
The rubber composition according to appendix 3, wherein the polymer having rubber elasticity is a functionalized natural rubber (appendix 5)
The rubber composition according to appendix 4, wherein the functionalized natural rubber is an epoxidized natural rubber.
(Appendix 6)
A rubber part obtained by using the rubber composition according to any one of appendices 1 to 5.
(Appendix 7)
A method for producing a rubber composition used at a predetermined temperature, comprising a step of blending an amount of coumarone resin determined by the following formula with 100 parts by mass of natural rubber, modified natural rubber or functionalized natural rubber.
Blending amount of coumarone resin (parts by mass) = (predetermined temperature (° C.) − 1.91) /0.356
(Appendix 8)
The method for producing a rubber composition according to appendix 7, wherein the functionalized natural rubber is an epoxidized natural rubber.
(Appendix 9)
A rubber part obtained by using the rubber composition produced by the method according to appendix 7 or 8.
(Appendix 10)
A rubber composition used in a predetermined temperature range obtained by blending 10 parts by mass or more of a coumarone resin with 100 parts by mass of a polymer having rubber elasticity, wherein the restitution rate measured in the predetermined temperature range is The rubber composition which is 1/5 or less of the polymer which has the rubber elasticity which does not contain.
(Appendix 11)
The rubber composition according to appendix 10, wherein the restitution rate is 1/10 or less of the rubber-elastic polymer not containing coumarone resin.
(Appendix 12)
A rubber composition comprising a polymer having rubber elasticity and a coumarone resin, wherein a temperature at which the impact absorption rate is minimum in a temperature range exhibiting rubber elasticity is higher than 20 ° C. object.
(Appendix 13)
The rubber composition according to appendix 12, wherein the amount of the coumarone resin is 10 parts by mass or more with respect to 100 parts by mass of the polymer having rubber elasticity.

Claims (9)

  A rubber composition containing 10 parts by mass or more of coumarone resin with respect to 100 parts by mass of a polymer having rubber elasticity.   The rubber composition according to claim 1, wherein the content of the coumarone resin is 20 parts by mass or more.   The rubber composition according to claim 1 or 2, wherein the polymer having rubber elasticity is natural rubber, modified natural rubber, or functionalized natural rubber.   The rubber composition according to claim 3, wherein the polymer having rubber elasticity is a functionalized natural rubber.   The rubber composition according to claim 4, wherein the functionalized natural rubber is an epoxidized natural rubber.   A rubber part obtained by using the rubber composition according to any one of claims 1 to 5. A method for producing a rubber composition used at a predetermined temperature, comprising a step of blending an amount of coumarone resin determined by the following formula with 100 parts by mass of natural rubber, modified natural rubber or functionalized natural rubber.
Blending amount of coumarone resin (parts by mass) = (predetermined temperature (° C.) − 1.91) /0.356   The method for producing a rubber composition according to claim 7, wherein the functionalized natural rubber is an epoxidized natural rubber.   A rubber part obtained by using the rubber composition produced by the method according to claim 7 or 8.

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