JPH0525328A - Composition for vibration-damping sheet - Google Patents

Abstract

PURPOSE:To obtain the subject composition applicable without necessitating the odor-elimination treatment in the formation of a vibration-damping sheet by compounding specific amounts of a polymer component vulcanizable with sulfur, a bituminous component and an inorganic filler and adding a vulcanization agent, etc., to the mixture. CONSTITUTION:The objective composition is produced by compounding (A) 100 pts.wt. of a polymer component vulcanizable with sulfur (in an amount to form an ebonite-like material), (B) 10-100 pts.wt. of a bituminous component, (C) 100-500 pts.wt. of an inorganic filler, (D) a vulcanization agent consisting of (i) a sulfur-based vulcanization agent, (ii) a thiuram-type vulcanization accelerator and (iii) zinc oxide as a vulcanization accelerating assistant, (E) 2.5-12.5mol of an odor-suppressing agent consisting of univalent or bivalent metal oxide based on 1 mol of the component (ii) and (F) other subsidiary materials such as foaming agent and plasticizer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration-damping sheet for damping vibration by adhering it onto a metallic substrate such as a floor of a vehicle, which is vibrated. The present invention relates to a composition for a vibration damping sheet used for producing a vibration damping sheet of a type. Particularly, the present invention relates to a composition for a vibration damping sheet, which facilitates maintenance of a work environment when the vibration damping sheet is installed on a vehicle floor or the like.

[0002] In the following description, "part" and "%" indicating a blending unit mean a weight unit unless otherwise specified.

[0003]

2. Description of the Related Art Conventionally, for damping the floor surface of a vehicle, a bituminous component (such as asphalt) is kneaded with an inorganic filler, butyl rubber, etc. and extruded to form a damping sheet. The damping sheet is set on the vehicle floor. After that, it was heated and softened so as to be along the floor surface and fused (see Japanese Patent Publication No. 56-52943).

However, in the above-mentioned bituminous damping sheet, it is necessary to make it thick in order to obtain a predetermined damping performance, which leads to an increase in weight, and in particular for automobiles where there is a strong demand for weight reduction. It was not desirable as a sheet.

Therefore, the same applicant as the present applicant has proposed a vibration damping sheet having the following structure (Japanese Patent Application No. 3-73).
No. 99: not yet published at the time of filing this application).

"10-100 parts of viscoelastic material, 100-500 of oriented inorganic filler per 100 parts of polymer component.
A vibration-damping sheet formed by molding a composition in which parts are blended, and further, a cross-linking agent and a foaming agent are blended, wherein the polymer component is a cross-linkable resin of 50 to 90%, and a rubber component 10. .About.50%, the vulcanizing agent is an amount capable of converting the polymer component into an ebonite state, and the addition amount of the foaming agent is an amount such that the expansion ratio is 1.5 to 5 times. "

[0007]

However, it has been found that a bad odor is generated when the damping sheet having the above-mentioned structure is installed on the floor surface of the vehicle body or the like. Therefore, from the standpoint of work environment conservation, it has become necessary to take special consideration into odor treatment.

In view of the above, it is an object of the present invention to provide a composition for a vibration damping sheet which does not require special consideration of the malodor treatment when constructing the vibration damping sheet.

[0009]

The vibration damping sheet of the present invention comprises:
The above problems are solved by the following configurations.

10 parts by weight of a bituminous component and 100 parts by 500 parts of an oriented inorganic filler are mixed with 100 parts of a sulfur vulcanizable polymer component, and further, a vulcanizing agent and a foaming agent are added. A rubber composition having a foaming formulation that is compounded with an auxiliary material, wherein the vulcanizing agent is a sulfur vulcanizing system containing a thiuram vulcanization accelerator and zinc oxide as a vulcanization accelerator aid. Further, in the composition for a vibration damping sheet having a composition in which the polymer component is blended in an amount capable of forming an ebonite, a monovalent or divalent metal oxide is contained with respect to 1 mol of the thiuram-based vulcanization accelerator. , 2.5-12.
It is characterized by being blended in an amount of 5 mol as an odor generation inhibitor.

[0011]

The function of the present invention is as follows:
As described above, a large amount of a thiuram vulcanization accelerator and a sulfur vulcanization agent containing zinc oxide as a vulcanization accelerator auxiliary are blended in order to enhance the vibration damping effect (proportional to rigidity). In 1 mol of the thiuram-based vulcanization accelerator, the monovalent or divalent metal oxide is 2.5 to 12.5.
The odor concentration is significantly reduced as shown in the test example described later, due to the constitution in which the odor generation inhibitor is mixed with each other. Therefore, in the composition for a vibration damping sheet of the present invention, it is not necessary to specially consider the malodor treatment.

The reason is presumed to be as follows.

For example, in the case of tetramethylthiuram disulfide (hereinafter abbreviated as "TMT"), as shown below, dimethyldithiocarbamic acid generated in the course of the vulcanization accelerating reaction mechanism is thermally decomposed to form dimethylamine and diamine. Carbon sulfide is generated. The dimethylamine and carbon disulfide are
Both have a bad odor.

[0014]

[Chemical 1]

The composition of the present invention contains a large amount of a metal oxide having a high reaction rate constant with dimethyldithiocarbamic acid and which does not substantially participate in the vulcanization reaction mechanism. Then, the dimethyldithiocarbamate-forming reaction in which the metal oxide reacts with the dimethyldithiocarbamic acid is competitively superior to the dimethyldithiocarbamic acid in comparison with the thermal decomposition reaction. Therefore, the thermal decomposition reaction of dimethyldithiocarbamic acid is suppressed, and the generation of odor-causing compounds such as dimethylamine and carbon disulfide is suppressed.

[0016]

DETAILED DESCRIPTION OF THE INVENTION The structure of the present invention will be described in detail below with reference to the drawings.

A. The first requirement is that the composition for a vibration damping sheet of the present invention contains 10 to 100 parts of a bituminous component and 100 to 500 parts of an inorganic filler with respect to 100 parts of a polymer component capable of sulfur vulcanization. And .

If the bituminous component is less than 10 parts, the loss factor (η) becomes relatively small, which is not desirable. Further, when it exceeds 100 parts, the polymer component becomes relatively small, and it is difficult to obtain the effect of increasing the rigidity by the polymer component. Further, if the blending amount of the inorganic filler is less than 100 parts, the rigidity of the vibration damping sheet cannot be sufficiently increased.
If it exceeds the range, the adhesion of the steel sheet will deteriorate and the workability will also deteriorate.

(1) The polymer component is not particularly limited as long as it is capable of sulfur vulcanization, but is preferably one having the structure described in the above-mentioned prior application.

That is, it comprises 50 to 90 wt% of a crosslinkable resin and 10 to 50 wt% of a rubber component. If the amount of the crosslinkable resin is too small, the rigidity of the vibration damping sheet cannot be expected to increase due to crosslinking, and if it is too large, the rubber component becomes relatively small and the workability deteriorates.

Examples of the crosslinkable resin include 1,2-polybutadiene, ethylene-vinyl acetate copolymer (EV
A), a block copolymer of an aromatic vinyl compound and a conjugated diolefin, and the like can be mentioned.

As the rubber component, natural rubber (N
R) or IR, BR, CR, NBR, IIR, EP
Various synthetic rubbers such as DM and SBR, and recycled rubbers thereof can be used.

(2) As the bituminous component, use is made of straight asphalt, blown asphalt, or other natural asphalt, or a mixture of two or more thereof.

(3) As the above-mentioned inorganic filler, an oriented one is preferable, and examples thereof include scaly fillers such as mica, graphite and glass flake, and further inorganic fiber fillers such as glass fiber.

B. In the above formulation, the present invention comprises a vulcanizing agent and a foaming agent blended together with other auxiliary materials, and the vulcanizing agent contains a thiuram vulcanization accelerator and zinc oxide as a vulcanization accelerator aid. A second requirement is that it is a sulfur vulcanization system and that the polymer component is blended in an amount capable of forming an ebonite.

The term "ebonite-like" means hard rubber-like (JIS A75 or more) when only the polymer component is cross-linked.
Say that. Unless it is formed into a substantially ebonite state, it cannot sufficiently contribute to the increase in the rigidity of the vibration damping sheet. Further, if the expansion ratio is too small, the bulkiness is not sufficient and the contribution to weight reduction is small, and if the expansion ratio is too large, problems tend to occur in strength.

(1) The above-mentioned thiuram vulcanization accelerator is
General-purpose compounds can be used, and specific examples include tetramethylthiuram disulfide (TMTD), tetramethylthiuram monosulfide (TMTM), tetraethylthiuram disulfide (TETD), dipentamethylenethiuram tetrasulfide (DPTT), and the like. You can

These thiuram vulcanization accelerators are
2-mercaptobenzothiazole (MBT), benzothiazylzosulfide (MB
Used in combination with a thiazole-based vulcanization accelerator such as TS).

(2) The compounding amount of each agent is 20 to 50% of sulfur (vulcanizing agent) per 100 parts of the polymer component when TMTD and MBTS are used in combination as a vulcanization accelerator.
Parts, zinc oxide (vulcanization acceleration aid): 5 to 15 parts, TMT
D: 5 to 15 parts, MBTS: 1 to 4 parts.

(3) The compounding amount of the above-mentioned foaming agent is usually such that the expansion ratio is 1.5 to 5 times.

As the above-mentioned foaming agent, those for usual rubber compounding, for example, dinitrosopentamethylenetetramine (DPT), azodicarbonamide (ADCA), p-
Toluenesulfonyl hydrazide (TSH), 4,4 '
-Oxybisbenzenesulfonyl hydrazide (OBS
H) and the like can be used. For example, in the case of DPT, it is 1 to 5 parts per 100 parts of the polymer component. And DPT
When using as a foaming agent, urea and its derivatives are used as an auxiliary agent.

(4) Examples of the other auxiliary materials include auxiliary materials used in rubber compounds such as process oil, plasticizer, lubricant, tackifier and the like.

C. In the composition of the present invention, a monovalent or divalent metal oxide is blended in an amount of 2.5 to 12.5 mol as an odor generation inhibitor with respect to 1 mol of the thiuram-based vulcanization accelerator. The composition is the third requirement.

If the compounding amount of the metal oxide as the odor generation inhibitor is less than 2.5 mol, the effect of the present invention (inhibition of generation of odor-causing compound) is difficult to be exerted, and even if it exceeds 12.5 mol, the odor is suppressed. The effect of suppressing the generation of the causative compound has reached saturation,
Useless.

The monovalent or divalent metal oxide is not particularly limited as long as it reacts with dimethyldithiocarbamic acid to produce dimethyldithiocarbamate, and zinc, iron, cadmium, magnesium, copper,
Mention may be made of metal oxides such as selenium, tellurium, sodium and potassium.

D. Manufacture and construction of damping sheet The above composition is usually kneaded with a kneader, bumper mixer, etc., then roll-rolled or extruded to form a sheet, and the sheet-shaped body is cut into a predetermined size to produce a sheet. To do.

The vibration damping sheet thus produced is set on the floor of the vehicle and placed in a drying oven (heating temperature: 140 to 160 ° C.).
Pass through. Then, the vibration damping sheet is softened by heating and conforms to the vehicle floor surface, and is vulcanized and foamed to form a vibration damping layer. At this time, dialkylamine and carbon disulfide, which are compounds causing an offensive odor, are hardly generated in the vulcanization reaction.

[0038]

[Test Example] In the following basic formulation, in addition to 10 parts of zinc oxide as a vulcanization accelerator, zinc oxide as an odor generation inhibitor was added in a variable amount of 0, 10, 20 and 30 parts. The composition was kneaded with a kneader and then extruded into a sheet having a thickness of 2 mm to prepare each damping sheet.

Basic compounding formulation Polymer component (1,2-polybutadiene) 70 parts Polymer component (NR) 30 parts Bituminous component (asphalt) 50 parts Process oil 40 parts Vulcanization accelerator (zinc oxide) 10 parts Odor control Agent (zinc oxide) Variable amount Stearic acid 2 parts Tackifier 20 parts Inorganic filler (mica) 300 parts Vulcanizing agent (sulfur) 30 parts Vulcanization accelerator (MBTS) 1.5 parts Vulcanization accelerator (TMTD) 10 parts Foaming agent (DPT) 5 parts Foaming auxiliary agent (urea-based auxiliary agent) 5 parts Foaming unvulcanized sheet 1g was put in a 300cc Erlenmeyer flask and heat-treated in a constant temperature bath at 140 ° C for 30 minutes,
The mixture was allowed to cool to room temperature, and the odor concentration was measured with a Gastec gas detector tube.

The following can be found from the results shown in FIG.

The content of zinc oxide as an odor generation inhibitor is 8 parts or more per 10 parts of TMTD (TM in terms of mol).
It can be seen that the odor is significantly reduced in the case of 2.5 mol or more per 1 mol of TD). Further, the compounding amount of zinc oxide as an odor generation inhibitor is 40 with respect to 10 parts of TMTD.
Even if it exceeds the part (1 mol per 1 mol of TMTD in terms of mol)
It can be seen that the odor concentration does not drop significantly further (even above 2.5 molar).

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the blending amount of zinc oxide and the odor concentration.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location F16F 15/02 Q 9138-3J // B32B 5/18 C08L 21:00

Claims (1)

Claim: What is claimed is: 1. 100 parts by weight of a sulfur-vulcanizable polymer component, 10 to 100 parts by weight of a bituminous component, and 100 to 500 parts by weight of an inorganic filler.
A rubber composition having a foaming formulation in which a vulcanizing agent and a foaming agent are blended together with other auxiliary materials, wherein the vulcanizing agent is a thiuram-based vulcanization accelerator, and a vulcanization accelerator auxiliary agent. A composition for a vibration-damping sheet, which is a sulfur vulcanization system containing zinc oxide, and in which the polymer component is blended in an amount capable of forming an ebonite state, wherein 1 mol of the thiuram-based vulcanization accelerator is used, A composition for a vibration damping sheet, comprising a monovalent or divalent metal oxide mixed in an amount of 2.5 to 12.5 mol as an odor generation inhibitor.