JP3294708B2 - High damping chloroprene rubber composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high damping chloroprene rubber composition capable of efficiently absorbing vibrational energy.

[0002]

2. Description of the Related Art In recent years, devices for absorbing vibration energy, that is, vibration isolation, vibration isolation, seismic isolation devices, and the like have been rapidly spreading. For example, seismic isolation construction methods for protecting buildings from earthquakes use seismic isolation rubber laminates. That is, the rubber layer and the iron plate are alternately combined to absorb vibration energy due to the earthquake between the ground and the building.

[0003] However, the conventionally used seismic isolation rubber laminate has insufficient damping performance of the rubber composition itself used and has a small effect of absorbing vibration energy. I was Therefore, there have been problems such as a complicated structure and high cost.

In general, as a method for evaluating the damping performance of a rubber composition, a loss coefficient (tan δ = loss elastic modulus / storage elastic modulus) obtained by measuring the viscoelasticity of a material is used. The higher the attenuation, the higher the attenuation. As the rubber having a high damping property, butyl rubber is best known, but it has problems such as large compression set, easy settling, poor workability, and low vulcanization rate, and its use field has been limited.

On the other hand, chloroprene rubber is known as a rubber material suitable for seismic isolation rubber laminates and the like because of its excellent balance of physical properties such as general rubber properties, weather resistance, heat resistance and cold resistance. Chloroprene rubber laminates are used for bearings on road bridges. However, since chloroprene rubber does not have sufficient damping performance, its improvement has been demanded.

As means for improving the damping performance of chloroprene rubber, JP-A-63-245449 discloses a chloroprene polymer having a number average molecular weight of 500 to 20,000 polymerized in the presence of a xanthogen disulfide compound.
A chloroprene rubber composition for vibration damping rubber containing the liquid chloroprene polymer is disclosed.

[0007] However, in the above invention, there was a problem that the elastic modulus was lowered by blending the liquid chloroprene polymer.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a chloroprene rubber having a better elastic modulus than conventional chloroprene rubber while maintaining the balance of general rubber properties, weather resistance, heat resistance, cold resistance and the like. An object of the present invention is to provide a rubber composition.

[0009]

Means for Solving the Problems In order to solve the above problems, the present inventors have made intensive studies and as a result, have found that a solid chloroprene polymer and a low molecular weight chloroprene polymer having a specific number average molecular weight are used. The present inventors have found that the chloroprene rubber composition contained therein is superior in elastic modulus to a chloroprene rubber composition containing a liquid chloroprene rubber polymer of the prior art, and the present invention has been accomplished.

That is, the present invention provides a GPC (gel permeation)
Chromatography) Measured in styrene conversion
A solid chloroprene polymer having an obtained number average molecular weight of 100,000 or more (provided that an acrylonitrile component is contained.
And except for the stuff), GPC (gel permeation chroma
Preparative chromatography) low molecular weight chloroprene polymer having a number average molecular weight determined in terms of styrene is 50,000 exceed 20,000 by measurement (however, unsaturated binding in one molecule
Acrylate containing at least two or more compounds
And / or contains a component consisting of polyfunctional methacrylate
About highly attenuating chloroprene rubber composition characterized by containing by excluding are).

The chloroprene polymer in the present invention is:
Both the solid chloroprene polymer and the low molecular weight chloroprene polymer refer to a homopolymer of 2-chloro-1,3-butadiene or a copolymer of 2-chloro-1,3-butadiene and other monomers. Here, as the other monomer, For example <br/> example, styrene emission, 2, 3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, acrylic acid, acrylic acid esters, Examples include methacrylic acid, methacrylic acid esters, isoprene, 1,3-butadiene and the like.

As the solid chloroprene polymer in the present invention, a solid chloroprene polymer which is solid at room temperature and can be used for general vulcanized rubber can be used, but it requires high general rubber physical properties and compression set properties. In this case, those having a high molecular weight are preferred, and those having a number average molecular weight of 100,000 or more, more preferably 150,000 or more.

The low molecular weight chloroprene polymer of the present invention has a number average molecular weight of more than 20,000 and 50,000.
It is as follows. The use of this polymer makes it possible to improve the elastic modulus, which has been a problem in the prior art. When the number average molecular weight is 20,000 or less, the effect of improving the damping property is recognized, but the elastic modulus cannot be improved. On the other hand, if the number average molecular weight exceeds 50,000, the effect of improving the damping property is greatly reduced, which is not preferable. However, as the number average molecular weight is larger, the elastic modulus is improved, so that a low molecular weight chloroprene polymer having a large number average molecular weight is used as much as possible within a range where the effect of improving the damping property does not decrease. It can be improved.

In the chloroprene rubber composition of the present invention, the higher the content of the low-molecular-weight chloroprene polymer in the chloroprene rubber composition, the more the effect of improving the damping property becomes remarkable, but the tensile strength and elastic modulus gradually increase. To reduce the content, it is preferable to adjust the content according to the required characteristics of the field of use. Particularly when high tensile properties, elastic modulus, and damping property are required, solid chloroprene polymer:
The low-molecular-weight chloroprene polymer has a weight ratio of 50:50 to
A range of 90:10 is preferred, and 60:40 to 80:20.
Is more preferable.

The method of polymerizing chloroprene can be any of emulsion polymerization, solution polymerization, and the like. The method of mixing a solid chloroprene polymer and a low-molecular-weight chloroprene polymer is a state of latex obtained by emulsion polymerization. , A method of mixing as a solution such as toluene, a roll, a method of mixing with a Banbury mixer, and the like.In the present invention, both the solid chloroprene polymer and the low molecular weight chloroprene polymer are produced by emulsion polymerization. It is preferable to mix in the state of the obtained latex.

In order to control the molecular weight of the solid chloroprene polymer and the low molecular weight chloroprene polymer in the present invention, a known molecular weight regulator may be used. As the molecular weight regulator, compounds containing at least one mercapto group in the molecule, for example, alkyl mercaptans such as methyl mercaptan, ethyl mercaptan, n-butyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, Compounds 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-mercapto-cyclo f <br/> key hexanol, mercapto alcohols such as 3-mercapto-1,2-propanediol, xanthogen disulfide, halogenated hydrocarbons such as carbon tetrachloride However, the present invention is not limited to these, and an appropriate one can be selected and used depending on the purpose.

The chloroprene rubber composition of the present invention is used after adding a vulcanizing agent and vulcanizing. Carbon black,
Fillers such as silica and clay, as well as process oils, plasticizers, antioxidants, lubricants and the like may be added. If necessary, other resins and rubbers can be blended as long as the physical properties are not impaired. There is no limitation on the compounding method and vulcanization method, and general operations on rubber can be performed.

The chloroprene rubber composition obtained according to the present invention has the general rubber properties characteristic of chloroprene rubber,
Excellent damping properties are obtained without impairing the balance of physical properties such as weather resistance, heat resistance, and cold resistance.It is suitable for seismic isolation rubber, such as foundation bearings for buildings and road bridges. It is suitable as a member for the purpose of absorbing vibration energy in the automobile field and the like.

[0019]

The present invention will be described below in detail with reference to examples.

Production Example (1) Production of chloroprene polymer Emulsion polymerization was carried out using a 5 l four-necked flask as a reactor under the polymerization recipe shown in Table 1 while continuously dropping potassium persulfate under a nitrogen atmosphere. went. The molecular weight of the high-molecular-weight chloroprene polymer and the low-molecular-weight chloroprene polymer was adjusted by adjusting the amount of n-dodecylmercaptan. As soon as the polymerization rate reached 65%, 100p of diethylhydroxylamine was added to all charged monomers.
pm was added to stop the polymerization reaction. Unreacted monomers were removed using a steam stripping method.

Method for Measuring Molecular Weight of Chloroprene Polymer The number average molecular weight of the chloroprene polymer obtained in (1) was determined in terms of styrene by GPC (gel permeation chromatography) measurement.

Example 1 and Comparative Examples 1-3 Chloroprene polymers polymerized in (1) were mixed in an emulsified state as shown in Table 2. The mixing ratio was shown by the weight ratio of the polymer. The rubber thus obtained was kneaded with an open roll kneader according to the compounding recipe shown in Table 3, and then kneaded.
Press vulcanization was performed at 0 ° C. for 20 minutes to obtain a vulcanized sheet having a thickness of 2 mm.

Method for measuring physical properties of vulcanized rubber Static shear modulus (GS) [kgf / cm2] is measured according to JIS K
According to the low elongation stress test of No. 6301, the stress at 25% elongation was determined and calculated according to the following equation. Static shear modulus (GS) = stress at 25% elongation × 1.
639 The loss factor (tan δ) is 38 m longer than the vulcanized sheet.
m, a width of 4 mm, and a thickness of 2 mm were punched out and a room temperature (23 ° C.), amplitude ± 1%, using a rheovibron DDV-25F (manufactured by Orientec) as a viscoelasticity measuring device.
The measurement was performed at a preload of 30 g and frequencies of 0.5 Hz and 15 Hz.

Table 4 shows the results of the above physical property measurements. From this result, by using a low molecular weight chloroprene polymer, tan δ is increased, and an effect of improving the damping property is recognized. However, when the number average molecular weight of the low molecular weight chloroprene polymer exceeds 50,000, the effect of improving the damping property is remarkably reduced, and when the number average molecular weight is less than 20,000, the elastic modulus is apparently reduced. That is, within the scope of the present invention, both effects of high elastic modulus and high damping can be achieved in a well-balanced manner.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

[Table 3]

[0028]

[Table 4]

[0029]

As described above, the chloroprene rubber composition produced according to the present invention has excellent physical properties such as damping property, elastic modulus and general rubber physical properties. Therefore,
The chloroprene rubber composition produced according to the present invention is required for the seismic isolation rubber laminate, general rubber properties, weather resistance,
Since it satisfies heat resistance, cold resistance, etc. and has excellent damping properties, it is not necessary to use a conventionally required viscous damper, so it is optimal as a seismic isolation rubber laminate. In addition,
Compared with a conventional chloroprene rubber composition containing a liquid chloroprene polymer having a number average molecular weight of 500 to 20,000 polymerized in the presence of a conventional xanthogen disulfide compound,
The chloroprene rubber composition of the present invention is superior in elastic modulus.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-245549 (JP, A) JP-A-51-124145 (JP, A) JP-A-55-3425 (JP, A) JP-A-7-245 292164 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 11/00

Claims (1)

(57) [Claims] 1. GPC (gel permeation chromatography)
Graphy) Number average of styrene conversion
Solid chloroprene polymer with a molecular weight of 100,000 or more
(However, excluding those containing acrylonitrile component)
And GPC (gel permeation chromatography)
-) The number average molecular weight obtained by measurement in terms of styrene is 2
A low-molecular-weight chloroprene polymer having a molecular weight of more than 000 and less than 50,000 (however, the unsaturated bond in one molecule is small.
And / or a multifunctional acrylate containing at least two
Contains components consisting of multifunctional methacrylate
A high-damping chloroprene rubber composition comprising: