JP3669874B2 - Anti-vibration rubber composition and anti-vibration member for automobile - Google Patents

Description

【００３７】
次に、鉄板をサンドブラスト処理をし、十分に脱脂処理後、市販の加硫接着剤でプライマー処理を施してから、実施例１〜３で調製された未加硫ゴム組成物の混練物を配置し、油圧プレスにて１７０℃×２０分間熱処理を行ったところ、いずれも剥離強度の高い加硫接着体となった。
【００３８】
【発明の効果】
本発明によれば、損失正接（ｔａｎδ）が０．３以上（自動車の乗り心地が良好）で、動倍率２．５以下（車内騒音が少ない）の防振特性を有し、耐熱性に著しく優れ、しかも成形加工性を損なわせない自動車用防振ゴム組成物が提供される。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an automotive anti-vibration rubber composition and an anti-vibration member having improved heat resistance.
[0002]
[Prior art]
Conventionally, an anti-vibration rubber is used in an engine mount or the like of an automobile in order to absorb engine vibration. The properties required for this anti-vibration rubber are anti-vibration properties that have a high elastic modulus and low dynamic magnification (dynamic shear modulus / static shear modulus), and an engine associated with higher output and higher speed of automobiles. Heat resistance against room temperature rise. The anti-vibration characteristics are characteristics related to the ride comfort of the automobile and the noise in the vehicle. The loss tangent (tan δ) at a frequency of 15 Hz (amplitude ± 1%) is about 0.3 or more, and the frequency is 100 Hz (amplitude ± 0.5%). ) Is preferably about 2.5 or less. On the other hand, the higher the heat resistance, the better.
[0003]
[Problems to be solved by the invention]
However, the anti-vibration rubbers which are composed of natural rubber and / or synthetic rubber, sulfur and other vulcanizing agents and carbon black have the anti-vibration characteristics satisfying the above-mentioned characteristics by various improvement proposals. With respect to heat resistance, the recent engine room temperature is 120 ° C. or higher, sometimes not enough for an increase of about 150 ° C., and often cracks and breaks at a temperature of about 120 ° C. Therefore, the advent of anti-vibration rubber having high heat resistance while maintaining the vibration characteristics is awaited.
[0004]
The present invention has been made in view of the above, and its purpose is that the loss tangent (tan δ) at a frequency of 15 Hz (amplitude ± 1%) is about 0.3 or more and the frequency is 100 Hz (amplitude ± 0.1%). An uncured anti-vibration rubber composition for automobiles capable of obtaining anti-vibration rubber having an anti-vibration characteristic of 2.5 or less and a sufficiently high heat resistance even when exposed to an environment of about 150 ° C. Is to provide.
[0005]
[Means for Solving the Problems]
That is, the present invention comprises an unvulcanized rubber composition comprising chloroprene rubber, a vulcanizing agent comprising a metal oxide and acetylene black, and the vibration characteristics of the vulcanized sheet have a loss tangent of 15 Hz in frequency ( tan δ) is 0.3 or more, the dynamic magnification of the frequency 100 Hz (amplitude ± 0.1%) is 2.5 or less, and the acetylene black has an average crystal layer thickness (Lc) of 25 A or more, ash content A rubber composition for automobile vibration damping, which is 0.02% by weight or less and an iodine adsorption amount is 80 mg / g or more. In this case, the vulcanizing agent is preferably one or more selected from zinc oxide, magnesium oxide, lead oxide, trilead tetraoxide, iron trioxide, titanium dioxide, and calcium oxide. Furthermore, the present invention provides a vibration isolating member for automobiles comprising the vulcanized adhesive body of the rubber composition and metal.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail.
[0007]
The rubber used in the present invention is preferably a chloroprene rubber from the viewpoint of a balance of heat resistance, oil resistance, weather resistance, and cold resistance.
[0008]
The chloroprene rubber referred to in the present invention is a solid chloroprene polymer or a low molecular weight chloroprene polymer, both of which are 2-chloro-1,3-butadiene homopolymer or 2-chloro-1,3-butadiene and others. It means a copolymer with the monomer. Here, the other monomer is not particularly limited as long as it is copolymerizable with 2-chloro-1,3-butadiene. For example, styrene, acrylonitrile, 2,3-dichloro-1,3-butadiene, -Chloro-1,3-butadiene, acrylic acid, acrylic ester, methacrylic acid, methacrylic ester, isoprene, 1,3-butadiene and the like.
[0009]
The solid chloroprene polymer is solid at ordinary temperature and is a general rubber for vulcanized rubber. However, when compression set characteristics are required, the number average molecular weight is 100,000 or more, particularly 150. 1,000 or more. The upper limit is about 600,000.
[0010]
The low molecular weight chloroprene polymer is a polymer having a number average molecular weight of about 500 to 50,000 obtained by polymerization in the presence of an alkyl mercaptan and / or mercapto alcohol, and has particularly good damping properties. Examples of the alkyl mercaptan include compounds containing at least one mercapto group in the molecule, such as methyl mercaptan, ethyl mercaptan, n-butyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, and the like. On the other hand, as the mercapto alcohol, a compound containing at least one mercapto group and at least one hydroxyl group in the molecule, for example, 2-mercapto-1-ethanol, 3-mercapto-1-propanol, 4-mercapto-1- Butanol, 2-mercaptocyclohexinol, 3-mercapto-1,2-propanediol and the like are used.
[0011]
In order to obtain a vibration-proof rubber having a small dynamic magnification, particularly a dynamic magnification of about 1.5 or less, a copolymer of a chloroprene monomer and a carboxyl group-containing vinyl monomer is used as the chloroprene rubber, and the solid chloroprene polymer and / or Alternatively, it is preferable to use a low molecular weight chloroprene polymer containing 30% by weight or more. Here, examples of the carboxyl group-containing vinyl monomer include acrylic acid, methacrylic acid, maleic acid, fumaric acid and the like, and the copolymer contains about 0.1 to 5 mol% of those components. Copolymerize.
[0014]
The vulcanizing agent for the chloroprene rubber is preferably a metal oxide, specifically zinc oxide, magnesium oxide, lead oxide, trilead tetroxide, iron trioxide, titanium dioxide, calcium oxide or the like. These are used singly or in combination of about 2 to 15 parts by weight per 100 parts by weight of chloroprene rubber.
[0016]
Examples of vulcanization accelerators for chloroprene rubber include thiourea, guanidine, thiuram, and thiazole, with thiourea being preferred. Examples of the thiourea vulcanization accelerator include ethylene thiourea, diethyl thiourea, trimethyl thiourea, triethyl thiourea, N, N′-diphenyl thiourea, and trimeryl thiourea is particularly preferable. The amount of the vulcanization accelerator used is preferably about 0.5 to 5 parts by weight per 100 parts by weight of chloroprene rubber.
[0017]
The acetylene black used in the present invention has an average crystal layer thickness (Lc) of 25 A or more, an ash content of 0.02 wt% or less, an iodine adsorption amount of 80 mg / g or more, and preferably a DBP oil absorption amount of 150 to 180 ml / 100 g. Acetylene black. Other acetylene blacks may not sufficiently improve the above vibration-proof characteristics and heat resistance, and may deteriorate the general characteristics of natural rubber and / or synthetic rubber and adhesion to metals. It is inappropriate as an anti-vibration rubber.
[0018]
That is, when the average thickness (Lc) of the crystal layer is less than 25 A, the thermal conductivity is lowered and the heat resistance is insufficient. If the ash content exceeds 0.02% by weight, the vulcanization of natural rubber and / or synthetic rubber will be adversely affected, and the molding processability will change significantly, making it difficult to adjust the molding process. In addition, the adhesiveness with the metal becomes poor. When the iodine adsorption amount is less than 80 mg / g, general characteristics such as the elongation and tensile strength of the rubber are deteriorated, and the vibration characteristics are not sufficiently improved. The upper limit of the iodine adsorption amount is not particularly limited, and may be about 120 mg / g, which is the intrinsic value of acetylene black.
[0019]
The proportion of acetylene black is preferably 20 to 120 parts by weight, particularly 40 to 80 parts by weight, per 100 parts by weight of chloroprene rubber . If the amount is less than 20 parts by weight, the vibration-proofing properties and heat resistance of the vibration-proof rubber are insufficiently improved. If the amount exceeds 120 parts by weight, the general properties of the rubber are impaired and the moldability is also lowered.
[0020]
In order to further reduce the dynamic magnification of the vibration-proof rubber composition of the present invention, it is preferable that a coupling agent of 10 parts by weight or less per 100 parts by weight of chloroprene rubber is blended.
[0021]
As the coupling agent, a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, a zircoaluminate coupling agent, or the like can be used, and among them, a silane coupling agent is preferable. Examples of silane coupling agents include aminosilanes such as propyltrimethoxysilane, mercaptosilanes such as mercaptopropyltrimethoxysilane, vinylsilanes such as vinyltriethoxysilane, methacrylsilanes such as methacryloxypropyltrimethoxysilane, and glycidides. Glycidoxy silane such as xylpropyltrimethoxysilane.
[0022]
Furthermore, the anti-vibration rubber composition of the present invention is blended with conventionally used lubricants, softeners, anti-aging agents, antioxidants, ultraviolet absorbers, ozone degradation inhibitors, tackifiers and the like. You can also. Examples of the lubricant include stearic acid, examples of the softener include paraffin, petrolatum, linseed oil, and asphalt, and examples of the antiaging agent include an amine compound and a phosphorus compound.
[0023]
The anti-vibration rubber composition of the present invention is a loss tangent (tan δ) having a frequency of 15 Hz when a sheet having a thickness of 2 mm obtained by press vulcanization at 150 ° C. for 20 minutes is molded and its anti-vibration characteristics are measured. Is 0.3 or more and the dynamic magnification of the frequency 100 Hz (amplitude ± 0.1%) is 2.5 or less. Such anti-vibration characteristics can be realized by selecting the types and proportions of the components of the anti-vibration rubber of the present invention.
[0024]
Here, a loss factor (tan δ) at a frequency of 15 Hz is obtained by cutting a test piece of 38 mm, width 4 mm, and thickness 2 mm from the vulcanized sheet, and at a temperature of 25 ° C., an amplitude ± 1%, a preload 30 g, and a frequency 15 Hz Measured under conditions. As the measuring device, a commercially available viscoelasticity measuring device (for example, “Leovibron DDV-25F” manufactured by Orientec Co., Ltd.) is used.
[0025]
The dynamic magnification was determined by measuring the stress at 25% elongation according to the low elongation stress test of JIS K 6301, and using the formula, static shear modulus Gs = stress at 25% elongation × 1.639. On the other hand, a commercially available viscoelasticity measuring device (for example, “Spectrometer VES-F” manufactured by Iwamoto Seisakusho Co., Ltd.) is used to determine the shear modulus Gs (kg / cm ² ). The storage elastic modulus E is measured under the condition of 1%), and is calculated from the formula, dynamic magnification = E / 3Gs.
[0026]
The vibration-proof member for automobiles of the present invention is composed of a vulcanized adhesive body of the above-mentioned vibration-proof rubber composition for automobiles and metal. There is no restriction | limiting in particular in the kind of metal used here. Generally, it is steel, but stainless steel, zinc, copper, brass, aluminum, etc., and alloys thereof are also used.
[0027]
In order to obtain a vulcanized adhesive body of a metal and the above-mentioned automotive anti-vibration rubber composition, it is desirable that the metal is sufficiently degreased in advance and subjected to primer treatment with a commercially available vulcanized adhesive. For example, a commercial product of the chloroprene rubber plummer is a combination of “Chemlock 205 (single layer coating)” and “Chemlock 220 (two layer coating)” manufactured by LOAD, “Metal Rock GS” manufactured by Toyo Chemical Laboratory, “ Metalock P "and the like.
[0028]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples, Comparative Examples, and Reference Examples.
[0029]
(1) To a solid chloroprene polymer four-necked flask, 95 parts of 2-chloro-1,3-butadiene (parts are parts by weight; the same applies hereinafter), 5 parts of 2,3-dichloro-1,3-butadiene, pure water 120 parts, 4 parts of disproportionated potassium rosin acid salt, 0.6 parts of β-naphthalenesulfonic acid formalin condensate Na salt and 0.14 parts of n-dodecyl mercaptan were charged, and potassium persulfate was continuously added in a nitrogen atmosphere. Emulsion polymerization was carried out at a polymerization temperature of 40 ° C. while dropping. When the polymerization rate reached 65%, 100 ppm of diethylhydroxylamine was immediately added to the charged monomers to stop the polymerization reaction. The number average molecular weight of the obtained solid chloroprene polymer was about 270,000.
[0030]
(2) Low molecular weight chloroprene polymer 4-necked flask, 900 parts 2-chloro-1,3-butadiene, 10 parts 2,3-dichloro-1,3-butadiene, 25 parts toluene, n-dodecyl as alkyl mercaptan A solution containing 12 parts of mercaptan was charged, the temperature was raised to 55 ° C., and then 1.5 parts of a toluene solution containing 0.5% by weight of α, α′-azobis-2,4-dimethylvaleronitrile as a polymerization initiator was used. The reaction was started by addition. Polymerization was continued at 55 ° C., and after 15 hours, 1 part of a toluene solution containing 0.02% by weight of p-tert-butylcatechol was added to terminate the polymerization. The polymerization rate of 2-chloro-1,3-butadiene was 72%. Next, a large excess of methanol was added to isolate the polymer, and then the benzene dissolution-methanol coagulation purification operation was repeated three times, and then the residual solvent was used at 110 ° C. and 1-2 mmHgabs using a thin film evaporator. The polymer was isolated by evaporation and a low molecular weight chloroprene polymer was produced and used.
[0031]
(3) Acetylene black Acetylene black having an average thickness (Lc), ash content, iodine adsorption amount and DBP oil absorption amount of various crystal layers shown in Table 1 was used.
[0032]
Examples 1-3 Comparative Examples 1-2
Solid chloroprene polymer 70 parts, low molecular weight chloroprene polymer 30 parts, acetylene black 40 parts, stearic acid 0.5 parts, MgO 4 parts, silica powder 8 parts, process oil 8 parts, lubricant 4 parts, ZnO 5 parts and vulcanization acceleration After mixing 1.2 parts of an agent (2-mercaptoimidazoline series) and kneading with an open roll, press vulcanization was performed at a temperature of 150 ° C. for 20 minutes to form a vulcanized sheet having a thickness of 2 mm.
[0033]
The obtained vulcanized sheet was measured for a loss factor (tan δ) at a frequency of 15 Hz, dynamic magnification, heat resistance, and normal properties (breaking strength, breaking elongation, hardness (JIS-A)) according to JIS K 6301. The results are shown in Table 1. The loss factor (tan δ) and dynamic magnification were measured according to the above, and the heat resistance was measured as follows.
[0034]
Heat resistance test:
A JISK6301 dumbbell type 1 tensile test piece was punched from the longitudinal direction of the sheet, left at 150 ° C. for 70 hours, returned to room temperature, and subjected to a tensile test at a rate of 200 mm / min. Measure. This measurement was performed in the same manner on the sheet before the test, and the residual ratio after the test (after the test / before the test) with respect to the stress at the break and the elongation at break was calculated.
[0035]
Reference example 1
A vulcanized sheet was molded and evaluated in the same manner as in Example 1 except that commercially available furnace black was used instead of acetylene black. The results are shown in Table 1.
[0036]
[Table 1]

[0037]
Next, the steel plate is sandblasted, fully degreased, and then subjected to primer treatment with a commercially available vulcanized adhesive, and then the kneaded product of the unvulcanized rubber composition prepared in Examples 1 to 3 is placed. Then, when heat treatment was performed at 170 ° C. for 20 minutes with a hydraulic press, all became vulcanized adhesives having high peel strength.
[0038]
【The invention's effect】
According to the present invention, the loss tangent (tan δ) is 0.3 or more (good driving comfort of an automobile), the dynamic magnification is 2.5 or less (in-vehicle noise is low), and the heat resistance is remarkably high. An anti-vibration rubber composition for automobiles that is excellent and that does not impair molding processability is provided.

Claims (3)

It consists of an unvulcanized rubber composition containing chloroprene-based rubber, a vulcanizing agent composed of a metal oxide and acetylene black. The vibration characteristics of the vulcanized sheet have a loss tangent (tan δ) of 0.3 Hz at a frequency of 15 Hz. As described above, the dynamic magnification at a frequency of 100 Hz (amplitude ± 0.1%) indicates 2.5 or less, and the acetylene black has an average thickness (Lc) of the crystal layer of 25 A or more and an ash content of 0.02 wt% or less. A rubber composition for automobile vibration damping, wherein the iodine adsorption amount is 80 mg / g or more. The automobile according to claim 1, wherein the vulcanizing agent is one or more selected from zinc oxide, magnesium oxide, lead oxide, trilead tetraoxide, iron trioxide, titanium dioxide, and calcium oxide. Anti-vibration rubber composition.   An anti-vibration member for automobiles comprising a vulcanized adhesive body of the rubber composition according to claim 1 or 2 and a metal.