JP5446179B2 - Rubber composition for joint members - Google Patents

Description

  The present invention relates to a rubber composition, and more particularly to a chloroprene rubber composition.

  Conventionally, on road bridges and the like installed on the ground, a gap portion for absorbing the expansion and contraction of the road is formed at regular intervals, and this gap portion, that is, the joint portion of the road bridge is provided with an expansion / contraction portion. A joint member made of a rubber-like elastic body is provided.

The rubber material forming such a joint member is required to have weather resistance and wear resistance, and chloroprene-based rubber materials are widely used (for example, see Patent Document 1).
In addition, such a joint member is prepared by charging an unvulcanized rubber into a hardware (mold) having a complicated structure, pressing the rubber down to the details by pressing, and vulcanizing and bonding the steel.
Therefore, depending on the structure of the complicated mold, there is a problem that unvulcanized rubber does not flow to the end portion and adhesion failure with the steel material is likely to occur.

Japanese Patent Laid-Open No. 2004-257038

Accordingly, an object of the present invention is to provide a rubber composition for a joint member that maintains good rubber properties such as viscosity, scorch resistance, and hardness, and also has good rubber flow performance.

As a result of intensive studies to solve the above problems, the present inventor has a rubber component, silica, diethylene glycol and sulfur containing specific amounts, and a rubber composition for a joint member containing no magnesium oxide has a viscosity, scorch resistance, It was found that the rubber physical properties such as hardness could be maintained well and the rubber flow performance was good, and the present invention was completed.
That is, the present invention provides the following (1) and ( 2 ).

(1) A rubber composition for a joint member containing a rubber component, silica, diethylene glycol and sulfur, and containing no magnesium oxide,
10-50 % by mass of the rubber component is chloroprene rubber,
The content of the silica is 2 to 15 parts by mass with respect to 100 parts by mass of the rubber component,
The diethylene glycol content is 0.1 to 2.0 parts by mass with respect to 100 parts by mass of the rubber component,
The rubber composition for joint members whose content of the said sulfur is 0.1-1.5 mass parts with respect to 100 mass parts of said rubber components.

(2) The rubber composition for a joint member according to (1), further containing 0.5 to 2.0 parts by mass of dithiomorpholine with respect to 100 parts by mass of the rubber component.

As will be described below, according to the present invention, it is possible to provide a rubber composition for a joint member that maintains good rubber properties such as viscosity, scorch resistance, and hardness, and also has good rubber flow performance.
Therefore, the rubber composition for joint members of the present invention can be suitably used as an expansion joint member for roads and bridges, and is very useful.

The present invention is described in detail below.
The rubber composition for joint members according to the first aspect of the present invention (hereinafter also referred to as “the rubber composition of the present invention”) contains a rubber component, silica, diethylene glycol and sulfur, and does not contain magnesium oxide. A composition comprising:
10-50 % by mass of the rubber component is chloroprene rubber,
The content of the silica is 2 to 15 parts by mass with respect to 100 parts by mass of the rubber component,
The diethylene glycol content is 0.1 to 2.0 parts by mass with respect to 100 parts by mass of the rubber component,
In the rubber composition, the sulfur content is 0.1 to 1.5 parts by mass with respect to 100 parts by mass of the rubber component.
Next, the rubber component, silica, diethylene glycol and sulfur contained in the rubber composition of the present invention will be described.

<Rubber component>
The said rubber component contained in the rubber composition of this invention will not be specifically limited if the 10-50 mass % is chloroprene rubber.
The content of the chloroprene rubber in the rubber component is preferably 15 to 50% by mass, and more preferably 20 to 40% by mass.
Specific examples of rubber other than chloroprene rubber include other diene rubbers such as natural rubber (NR) and isoprene rubber (IR).

  In the present invention, it is preferable to use chloroprene rubber and natural rubber in combination as the rubber component. Specifically, for example, chloroprene rubber is contained in an amount of 20 to 40% by mass, and natural rubber is contained in an amount of 60 to 80% by mass. A rubber component is mentioned.

<Silica>
A conventionally well-known thing can be used for the said silica contained in the rubber composition of this invention.
Specific examples of silica include fumed silica, calcined silica, precipitated silica, pulverized silica, and fused silica.
Silica preferably has an average aggregate particle diameter of 5 to 50 μm, more preferably 5 to 30 μm.

  In this invention, content of the silica in a rubber composition is 2-15 mass parts with respect to 100 mass parts of said rubber components, It is preferable that it is 5-15 mass parts, It is 7-12 mass parts. Is more preferable.

<Diethylene glycol>
The diethylene glycol contained in the rubber composition of the present invention is a compound represented by a chemical formula of (CH ₂ OHCH ₂ ) ₂ O. As the diethylene glycol, a commercial product manufactured by Nippon Shokubai Co., Ltd. can be used.

  In this invention, content of the said diethylene glycol is 0.1-2.0 mass parts with respect to 100 mass parts of said rubber components, It is preferable that it is 0.5-1.5 mass parts, 0 More preferably, it is 7 to 1.2 parts by mass.

In the present invention, by using the silica and the diethylene glycol together in the above-described content, the rubber physical properties such as viscosity, scorch resistance and hardness are maintained well, and the rubber flow performance is made good. Can do.
This effect is considered to be an effect obtained by improving the dispersion of silica by blending diethylene glycol, but it is also clear from the comparison between Comparative Example 3 and Example 1 shown in [Example] described later. As described above, the rubber flow performance after being left in a 110 ° C. gear oven for 90 minutes is a remarkable effect.

  In the present invention, from the viewpoint of improving dispersibility of the silica and the diethylene glycol in the rubber composition, the silica and the diethylene glycol are in a ratio of 100 to 200 parts by mass of the diethylene glycol with respect to 100 parts by mass of the silica. It is preferable to mix | blend as a mixture mix | blended with.

<Sulfur>
As the sulfur contained in the rubber composition of the present invention, those conventionally known as vulcanizing agents can be used.
Specific examples of the sulfur include powdered sulfur, precipitated sulfur, highly dispersible sulfur, surface-treated sulfur, insoluble sulfur and the like. These may be used alone or in combination of two or more. You may use together.

  In the present invention, the sulfur content is 0.1 to 1.5 parts by weight, preferably 0.2 to 1.0 parts by weight, based on 100 parts by weight of the rubber component. More preferably, it is 2 to 0.7 parts by mass.

The rubber composition of the present invention is a rubber composition not containing magnesium oxide.
In the present invention, it is possible to improve the rubber flow performance by not blending magnesium oxide. This effect can be seen from a comparison between Comparative Example 1 and Comparative Example 2 shown in [Examples] described later. Magnesium oxide is generally blended as an acid acceptor in a chloroprene rubber composition. Considering this, it is a very surprising effect.

Moreover, it is preferable that the rubber composition of this invention uses dithiomorpholine together with the said sulfur.
By using the dithiomorpholine in combination, the rubber physical properties such as hardness become better without impairing the scorch resistance of the rubber composition of the present invention obtained.
In this invention, it is preferable that content of the said dithiomorpholine is 0.5-2.0 mass parts with respect to 100 mass parts of said rubber components, and is 0.5-1.5 mass parts. Is more preferable.

Further, the rubber composition of the present invention preferably contains an inorganic filler. Specific examples thereof include carbon black, T-clay, kaolin clay, wax stone clay, sericite clay, calcined clay, and diatomaceous earth. Heavy calcium carbonate, magnesium carbonate, aluminum hydroxide, barium sulfate, talc, aggregates of quartz and kaolinite, and the like.
Of these, carbon black is preferred because of its excellent rubber reinforcing effect and excellent rubber modulus, tensile strength, elongation at break and shear modulus after vulcanization of the rubber composition of the present invention.
In this invention, it is preferable that it is 25-45 mass parts with respect to 100 mass parts of said rubber components, and, as for content of the said carbon black, it is more preferable that it is 30-40 mass parts.

The rubber composition of the present invention can contain other additives as necessary within a range not impairing the object of the present invention.
Examples of the additive include a scorch inhibitor, a vulcanization accelerator, an anti-aging agent, a plasticizer, a softening agent, a vulcanization aid, a flame retardant, a weathering agent, and a heat resistance agent.

Specific examples of the scorch inhibitor include N- (cyclohexylthio) phthalimide.
In the present invention, the content of the scorch inhibitor is preferably 0.5 parts by mass or less with respect to 100 parts by mass of the rubber component.

Specific examples of the vulcanization accelerator include sulfenamides such as N-cyclohexyl-2-benzothiazole sulfenamide (CBS); thiazoles such as mercaptobenzothiazole; tetramethylthiuram monosulfide and the like. Thiurams; stearic acid; and the like.
Specific examples of the antiaging agent include ketone / amine condensates such as TMDQ; amines such as DNPD; monophenols such as styrenated phenol; and the like.
Specific examples of the plasticizer include phthalic acid derivatives (for example, DBP, DOP and the like), sebacic acid derivatives (for example, DBS and the like) monoesters, and the like.
Specific examples of the softening agent include paraffinic oil (process oil).

  The production (preparation) method of the rubber composition of the present invention is not particularly limited. For example, an unvulcanized rubber composition containing the above-described components can be prepared by kneading using a known method and apparatus. .

The rubber composition according to the second aspect of the present invention is a rubber composition containing a rubber component, silica, diethylene glycol and sulfur and not containing magnesium oxide,
10% by mass or more of the rubber component is chloroprene rubber,
30 g of the rubber composition was left in a gear oven at 110 ° C. for 90 minutes, and then the rubber composition was charged into a spider mold having an orifice diameter of 1.5 mm, and the surface of 0.05 MPa was applied at 120 ° C. for 10 minutes. The rubber composition has an extrusion amount of 4.0 g or more when extruded by pressure.
Here, the condition of “left in a gear oven at 110 ° C. for 90 minutes” is that the heat history during manufacture when the rubber composition according to the second aspect of the present invention is used as an expansion joint member is charged into a mold. Is assumed.
Moreover, the condition of “surface pressure of 0.05 MPa at 120 ° C. for 10 minutes” is a condition that can ensure the fluidity (extrudability) of the rubber composition charged in the mold and started vulcanization.
Further, in the present invention, the extrusion amount is a value measured using ASTM Spider Mold (orifice diameter: 1.5 mm) manufactured by DESENCO as the spider mold under the above-described conditions.
And if the said extrusion amount will be 4.0 g or more, it can be judged that the space of the complicated pattern in a metal mold | die for shaping | molding can be filled easily, and the rubber | gum flow performance of a rubber composition is sufficiently excellent. It can be said.

FIG. 1 shows a schematic perspective view of the spider mold.
In FIG. 1, the code | symbol 10 represents the whole spider mold, and comprises the cover part 11, the upper mold 13 which provided the preparation part 12 of the rubber composition, and the lower mold 14 which is a rubber receiving part. is there. Also, the orifice diameter (1.5 mm) of the spiral mold is located at the center of the bottom of the preparation part 12, and the prepared rubber composition is pushed out by the injection part 15 provided in the lid part 11 and the lower mold 14. The diameter of an orifice (hole) (not shown) that flows into

  Such a rubber composition according to the second aspect of the present invention contains the above-described rubber component, silica, diethylene glycol and sulfur, and contains magnesium oxide, similarly to the rubber composition according to the first aspect of the present invention. Although it is a rubber composition which does not, if the said extrusion amount becomes 4.0 g or more, content of a silica, diethylene glycol, and sulfur will not be specifically limited.

Next, the expansion joint member which is a suitable usage mode of the rubber composition according to the first and second modes of the present invention will be described in detail.
As described in [Background Art], the expansion joint member was charged with unvulcanized rubber in a complicated structure (mold) and pressed to push the rubber down to the details to be vulcanized and bonded to the steel material. Something is used.

FIG. 2 is a schematic cross-sectional view of a joint portion of a road bridge including an expansion joint member that is a preferred mode of use of the rubber composition according to the first and second aspects of the present invention.
In FIG. 2, the code | symbol 1 represents the whole joint part of a road bridge, the code | symbol 2 represents an anchor plate, the code | symbol 3 represents a side plate, and the code | symbol 4 represents a 1st expansion joint member. Reference numeral 5 represents a load support plate, reference numeral 6 represents a second expansion joint member, reference numeral 7 represents an anchor bar, and reference numeral 8 represents a road bridge.
Here, since it is necessary to form the first expansion joint member 4 using a hardware (mold) having a complicated structure, it is preferable to use the rubber composition according to the first and second aspects of the present invention. Can be formed.

  The rubber composition according to the first and second aspects of the present invention is also suitable as an elastic board or rubber layer of a road bridge expansion / contraction device proposed by the present applicant in Japanese Patent Application Laid-Open No. 2003-193411. Can be used for

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely according to an Example, this invention is not limited to the following Example.

(Examples 1 and 2, Comparative Examples 1 to 5)
Each compound was blended and kneaded for 5 minutes in a B-type Banbury mixer so as to have the composition shown in Table 1 below (unit: parts by mass) to prepare an unvulcanized rubber composition.
The physical properties of the obtained rubber compositions were measured according to the methods shown below. The results are shown in Table 1 below.

<Mooney viscosity>
About each obtained unvulcanized rubber composition, according to JISK6300-1-2001, Mooney viscosity was measured on condition of preheating time 1 minute and test temperature 125 degreeC using the L-shaped rotor.

<Mooney coach>
About each obtained unvulcanized rubber composition, according to JIS K6300-1-2001, the Mooney viscosity is continuously measured under the conditions of a preheating time of 1 minute and a test temperature of 125 ° C. in accordance with JIS K6300-1-2001. did. The minimum value of the Mooney viscosity was V _m. Moreover, Mooney viscosity was measured Mooney scorch time (minute) until the 5 points from V _m.
The results are shown in Table 1. The Mooney scorch time is an index of scorch (rubber burn) and is preferably longer.

<Hardness>
The obtained unvulcanized rubber compositions were vulcanized for 60 minutes under a surface pressure of 3.0 MPa using a press molding machine at 148 ° C. to prepare a vulcanized sheet having a thickness of 2 mm.
For the two vulcanized sheets stacked, the Shore A hardness was measured according to “Type A durometer hardness test” of JIS K6253-1997.

<Lambourn abrasion resistance index (wear resistance)>
The obtained unvulcanized rubber compositions were vulcanized for 60 minutes under a surface pressure of 3.0 MPa using a press molding machine at 148 ° C., according to “vulcanized rubber and heat of JIS K6264-2: 2005”. A test piece having a shape according to “9.3 Test piece” of “Plastic rubber—How to determine wear resistance” was prepared.
About the produced test piece, the test which changed the slip ratio to 50% and the load to 15N among the conditions as described in "9.4 Test method" of the same JIS was done.

<Rubber flow performance>
(initial)
When 30 g of each obtained unvulcanized rubber composition was charged into a spider mold (model: ASTM Spider Mold, orifice diameter: 1.5 mm) and extruded at 120 ° C. for 10 minutes at a surface pressure of 0.05 MPa The amount of extrusion was measured.
(After treatment)
30 g of each of the resulting unvulcanized rubber compositions was left in a gear oven at 110 ° C. for 90 minutes, and the subsequent rubber composition was charged into a spider mold (model: ASTM Spider Mold, orifice diameter: 1.5 mm). The amount of extrusion when extruded at a surface pressure of 0.05 MPa at 120 ° C. for 10 minutes was measured.

The following were used for each component in Table 1.
・ Chloroprene rubber: Shoprene GS, manufactured by Showa Denko ・ Natural rubber: STR20, manufactured by TECK BEE HANG ・ Carbon black: Diamond Black I, manufactured by Mitsubishi Chemical ・ Silica: Nip seal VN3, manufactured by Tosoh Silica ・ Diethylene glycol: Nippon Shokubai -Magnesium oxide: Kyowa Mag 150, manufactured by Kyowa Chemical Industry Co., Ltd.-Scorch inhibitor: Retarder CTP, manufactured by Ouchi Shinsei Chemical Co., Ltd.-Sulfur: powder sulfur, manufactured by Hosoi Chemical Co., Ltd. Chemical industry

  As is apparent from Table 1, the rubber compositions (Examples 1 and 2) containing specific amounts of the rubber component, silica, diethylene glycol and sulfur and not containing magnesium oxide are rubbers such as viscosity, scorch resistance and hardness. It was found that the physical properties were kept good and the rubber flow performance was good.

FIG. 1 is a schematic perspective view of a spider mold. FIG. 2 is a schematic cross-sectional view of a joint portion of a road bridge including an expansion joint member which is a preferred usage mode of the rubber composition according to the first and second aspects of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Seam part of road bridge 2 Anchor plate 3 Side plate 4 First expansion joint member 5 Load support plate 6 Second expansion joint member 7 Anchor bar 8 Road bridge 10 Spider mold 11 Lid part 12 Preparation part 13 Upper mold 14 Lower mold ( Rubber receiving part)
15 Injection part

Claims (2)

A rubber composition for a joint member containing a rubber component, silica, diethylene glycol and sulfur and not containing magnesium oxide,
10-50 % by mass of the rubber component is chloroprene rubber,
The content of the silica is 2 to 15 parts by mass with respect to 100 parts by mass of the rubber component,
The diethylene glycol content is 0.1 to 2.0 parts by mass with respect to 100 parts by mass of the rubber component,
A rubber composition for joint members , wherein the sulfur content is 0.1 to 1.5 parts by mass with respect to 100 parts by mass of the rubber component. The rubber composition for a joint member according to claim 1, further comprising 0.5 to 2.0 parts by mass of dithiomorpholine with respect to 100 parts by mass of the rubber component.

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