JPH03287652A - Vibration-damping composition - Google Patents

Abstract

PURPOSE:To prepare a thermoplastic vibration-damping compsn. which exhibits high vibration-damping properties over a wide temp. range and can be molded without the necessity for a complex vulcanizing step by compounding a specific block copolymer with an iron oxide powder. CONSTITUTION:100 pts.wt. block copolymer is compounded with 30-1000 pts.wt. iron oxide powder to give a vibration-damping compsn., which can be used as a material for damping vibration and noise and exhibits excellent vibration- damping properties over a wide temp. range from room temp. to a high temp. The block copolymer has a number-average mol.wt. of 30,000-300,000 and comprises a block consisting of a vinyl arom. monomer and having a number- average mol.wt. of 2,500-40,000 and a block consisting of isoprene or an isoprene- butadiene mixture and having a number-average mol.wt. of 10,000-200,000, a 3,4-bond content and a 1,2-bond content each of 40% or higher, and a peak of the main dispersion of tan delta at 0 deg.C or higher.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a composition with excellent vibration damping performance.

[Conventional technology]

In recent years, noise and vibration problems have become major social problems due to the development of transportation such as automobiles, and efforts are being made to reduce vibration and noise inside automobiles. In addition, in offices and households, there is a strong demand for low vibration and low noise for office equipment such as printers, and household electrical appliances such as washing machines, refrigerators, and vacuum cleaners, and low vibration and low noise are the selling points of products. It is becoming.

Conventionally, in order to reduce vibration and noise, various springs,
Anti-vibration rubber etc. have been used. The method of using springs and anti-vibration rubber reduces the generation of vibration and noise by providing anti-vibration, that is, blocking the transmission of vibration.

However, as demands regarding vibration and noise are diversifying, these methods alone can no longer meet the demands. Therefore, recently, a method called vibration damping, which suppresses the vibration itself, has become widely used.

[Problem to be solved by the invention]

In this method, a viscoelastic body is attached to or sandwiched between a vibrating body, and the viscoelastic body converts vibrational energy into thermal energy to suppress vibration.

Among such damping materials, NR, IIR, and SBR all have a narrow temperature range in which they exhibit damping performance, and their performance is particularly insufficient in high temperature ranges. Furthermore, when a rubber component is used, a vulcanization operation is required after molding, which requires a great deal of time and effort.

An object of the present invention is to provide a thermoplastic vibration damping composition that exhibits high vibration damping performance over a wide temperature range and that can be used in molding without complicated vulcanization operations.

[Means to solve the problem]

According to the present invention, the above problem is solved when the number average molecular weight is 2500 to
A block of 40,000 vinyl aromatic monomers (
A) and isoprene or isoprene-butadiene, with a number average molecular weight of 10,000 to 200,000,
3.4 bond and 1.2 bond content is 40% or more,
Consisting of block (B) having a main dispersion peak of tan δ at 0°C or higher, the number average molecular weight is 30,000 to 3
This is achieved by a composition consisting of 100 parts by weight of a block copolymer having a formula of 0.00000 and 30 to 1000 parts by weight of iron oxide powder.

The present invention will be explained in more detail below.

The number average molecular weight of the vinyl aromatic block (A) is 2500
~40,000. If the molecular weight is less than 2,500, the performance as a composition will deteriorate, and if it exceeds 40,000, the melt viscosity will become too high, and mixing with iron oxide powder will not be successful, making it impossible to obtain a composition with sufficient performance.

The proportion of the vinyl aromatic block (A) in the block copolymer is preferably 5 to 50% by weight. If this ratio is less than 5%, the mechanical properties of the block copolymer will be insufficient, and on the other hand, if it exceeds 50%, the viscosity will become extremely high, making processing such as mixing difficult, and vibration damping performance will decrease. .

Further, as the second component of the block copolymer used in the present invention, isoprene or isoprene-butadiene is preferably used in combination. When other monomers are used, for example, butadiene alone, the temperature at which vibration damping performance is exhibited is less than 0°C even if the bond content is increased, and the function at the temperature actually used is Not obtained,
It has little practical significance. In the case of isoprene, 3 of the present invention
．． By having a bond content of 4 bonds and 1.2 bonds (hereinafter these may be collectively referred to as vinyl bond content), it exhibits vibration damping performance in a practical temperature range from approximately 0°C to around 50°C. This makes it possible to handle a wide range of applications, which is extremely meaningful in practice. When using isoprene-butadiene together, the ratio of isoprene is 40
% or more, vibration damping performance is exhibited at temperatures of 0°C or higher. When isoprene-butadiene is used in combination, the form of the block (B) may be random, block, or thiobard.

The content of 3.4 bonds and 1.2 bonds in block (B) of the block copolymer of the present invention is 40% or more (100%
) is used. If the vinyl bond content is less than 40%, sufficient vibration damping performance cannot be obtained in the normal operating temperature range, which is not preferable.

In addition, t obtained by measuring the viscoelasticity of the block copolymer
It is necessary that the temperature of the peak of the main dispersion of an δ (loss tangent) is 0° C. or higher. Even if there is a peak only at a temperature lower than 0° C., sufficient vibration damping performance cannot be obtained in the normal temperature range.

Moreover, the number average molecular weight of block (B) is 10,000 to 2
A value in the range 00000 is used. If the molecular weight is smaller than the above range, the elastic properties will be impaired, which is not preferable. Moreover, if it is too large, the fluidity will deteriorate, which is not preferable.

The number average molecular weight of the obtained block copolymer is 30,000
It is necessary to be in the range of ~300,000.

If the molecular weight is less than 30,000, mechanical properties such as strength at break and elongation of the block copolymer itself will be lowered, and the strength of the composition will be lowered, which is not preferable. Also, 3
If it exceeds 00000, workability deteriorates, which is not preferable. From this point of view, the molecular weight of the block copolymer is more preferably in the range of 80,000 to 250,000.

The block morphology of the block copolymer is represented by A (BA), , (AB). Here, A represents a block consisting of an aromatic vinyl monomer, B represents a block consisting of isoprene or isoprene-butadiene, and n is an integer of 1 or more. Among these, A-B
-A form is most preferably used.

In the present invention, the block copolymer can be obtained by the following various methods.

First, the block copolymer is produced by (a) sequentially polymerizing an aromatic vinyl compound, isoprene, or isoprene-butadiene using an alkyllithium compound as an initiator, and (b) polymerizing an aromatic vinyl compound and then isoprene or isoprene-butadiene. and coupling this with a coupling agent, or (c) isoprene or isoprene-coupling using a dilithium compound as an initiator.
Examples include a method of sequentially polymerizing butadiene and then an aromatic vinyl compound.

Examples of alkyl lithium compounds include alkyl compounds in which the alkyl residue has 1 to 10 carbon atoms,
Particularly preferred are methyllithium, ethyllithium, pentyllithium, and butyllithium. As the coupling agent, dichloromethane, dibromomethane, dichloroethane, dibromoethane, dibromobenzene, etc. are used.

Examples of dilithium compounds include naphthalene dilithium,
Examples include dilithiohexylbenzene. The amount used is determined depending on the desired molecular weight, but approximately 0 parts of each initiator is used per 100 parts by weight of all monomers used in polymerization.
．． 01-0.2 parts by weight, coupling JPI O,04
It is used in a range of about 0.8 parts by weight.

The microstructure of the isoprene or isoprene-butadiene moiety has 40% or more vinyl bonds and 01 or more t.
In order to have a main dispersion peak of an δ, a Lewis base is used as a cocatalyst during the polymerization of isoprene or isoprene-butadiene. Examples of Lewis bases include ethers such as dimethyl ether, diethyl ether, and tetrahydrofuran, glycol ethers such as ethylene glycol dimethyl ether and diethylene glycol dimethyl ether, triethylamine, N, N,
N',N'-tetramethylethylenediamine (TM
EDA), amine compounds such as N-methylmorpholine, and the like. The amount of these Lewis bases used is approximately 0.1 to 1000 per mole of lithium in the polymerization catalyst.
This is twice the range.

It is preferable to use a solvent during the polymerization to facilitate control. As the solvent, an organic solvent inert to the polymerization catalyst is used. In particular, aliphatic, alicyclic, and aromatic hydrocarbons having 6 to 12 carbon atoms are preferably used. Examples include hexane, heptane, cyclohexane, methylcyclohexane, benzene, and the like.

Regardless of the polymerization method used, the polymerization is carried out at a temperature of 0 to 80°C for a period of 0.5 to 50 hours.

After the reaction, the block copolymer is produced by coagulating the reaction solution with methanol or the like and then drying it by heating or under reduced pressure.
It can be obtained by pouring the reaction solution into boiling water to azeotropically remove the solvent, followed by drying by heating or under reduced pressure.

The iron oxide powder, which is another essential component used in the present invention, includes α-FeOO)1, βFe0
OH, hydrous ferric oxide powder such as r-Fe00H and δ-Fe00H, ferric oxide powder such as α-Fe, 03, TF
ezes and Fe, 0. Magnetic iron oxide powder such as Zn.

Mn + Co + Ni + Cu + Mg +
One type of iron oxide powder selected from spinel type ferrite powder containing one or more metals selected from Li and magnetobrambite type ferrite powder containing either Ba or Sr or Ba and Sr. Two or more types can be used.

These iron oxide powders can be used in any form such as granules, spindles, needles, and plates. Furthermore, the average particle size of the iron oxide powder is approximately 0.05 to 100 μm. Considering dispersibility in resin, 0.05~
10 μm is preferred.

In the composition of the present invention, iron oxide powder is mixed in an amount of 30 to 1000 parts by weight with respect to 100 parts by weight of the block copolymer. If the proportion of the block copolymer is less than this, it will be difficult to obtain a molded product, and if it is too large, the effect of adding iron oxide powder will be lost, which is not preferable.

The composition of the present invention is used by kneading and molding a block copolymer and iron oxide powder using a kneader-1 extruder, an injection molding machine, or the like.

The composition of the present invention contains a block copolymer and iron oxide powder as essential components, but other polymers may be blended and used as long as they do not impair the spirit of the present invention. An example is NR.

IR, BR, SBR, EPDM, EPR, styrene-
Examples include conjugated diene block copolymers and hydrogenated products thereof. The blend ratio of these polymers is approximately 30f
It is preferable that i is 1 part or less.

The composition of the present invention is used after being crosslinked depending on the case. Sulfur, peroxide, etc. are used as the crosslinking agent. Crosslinking can be readily carried out using conventional methods and equipment used for crosslinking conventional rubbers. The appropriate amount of the crosslinking material to be used is 0.5 to 20 parts by weight of sulfur and 0.1 to 20 parts by weight of peroxide per 100 parts by weight of the block copolymer.

The composition of the present invention can be used as a molded product as it is, or by being sandwiched or attached to steel plates, plastics, wood, etc.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.

In addition, each measurement value in an Example was calculated|required by the following method.

Molecular weight was determined by GPC.

The microstructure was measured by NMR spectrum and was found to be 4.8 ppm.
, from the ratio of the peaks of 3.4 bonds and 1.2 bonds at 5.8 ppa and the peaks of 1.4 bonds at 5,3 ppIM, 3
．． The contents of 4 bonds and 1.2 bonds were calculated.

The tan δ was measured using a Rheopybron (manufactured by Orientik) at a frequency of 11 Hz.

Reference Example In a pressure-resistant reactor that has been dried and purged with nitrogen, polymerization is carried out by adding styrene monomer, isoprene monomer, and styrene monomer in this order, using cyclohexane as a solvent, n-butyllithium as a polymerization catalyst, and TMEDA as a vinylizing agent. Molecular weight 161000, polystyrene block molecular weight 9900, vinyl bond amount (total of 3, 4 and 1.2 bond amounts) 79.9%, tan δ absorption peak temperature 39.7
C. block copolymer (A) was obtained.

Examples 1 to 2 and Comparative Example 1 The block copolymer obtained in the reference example and the iron oxide powder manufactured by Toda Kogyo Co., Ltd. (granular magnetite powder, average particle size 0.
A composition was prepared by kneading 27μ) at 170"C using a Brabender according to the recipe shown in Table 1.The obtained composition was press-molded at 200"C to form a sheet, and the tan δ was measured. I did it.

For comparison, the block copolymer monomer obtained in Reference Example was also measured in the same manner.

Examples 3 to 5 Molding and measurement were carried out in the same manner as in Example 1, except that granular hematite powder (average particle size 0.14μ) manufactured by Toda Kogyo Co., Ltd. and granular Magneka ÷÷ were used as iron oxide powder. went.

The measurement results of Examples 1 to 5 are shown in FIG. 1 and FIG. 2, respectively. The block copolymer alone begins to flow at around 80°C and no longer exhibits practical physical properties, but when mixed with iron oxide powder, the flow is suppressed, and the tan δ curve shows a high value and almost constant value. . From the above, it can be seen that the composition of the present invention exhibits an excellent vibration damping effect in a wide range from room temperature to high temperature.

Table 1 12345 1 Block copolymer (A) 2550252525
100 iron oxide powder a 7550 b 75 c 75 d 75 a: Granular magnetite powder, average particle size 0.27μb=
Granular hematite powder, average particle size 0.14μ [Effects of the invention] The composition of the present invention, which is characterized by combining a block copolymer with a specific molecular structure and iron oxide powder, is characterized by the ability to generate vibrations and noise. It can be used as a material to reduce vibration, and has excellent vibration damping performance over a wide temperature range from room temperature to high temperature.

[Brief explanation of the drawing]

Figure 1 shows the tan δ of block copolymer (A) (see Comparative Example 1) and block copolymer (A) blended with granular magnetite powder (see Examples 1 and 2).
The absorption curve of Figure 2 shows block copolymer (A)
The granular hematite is shown in each figure.

Claims (1)

[Claims] 1) A block (A) consisting of a vinyl aromatic monomer with a number average molecular weight of 2,500 to 40,000 and isoprene or isoprene-butadiene, with a number average molecular weight of 10,000 to 200,000 and a 3, 4 bond and 1, 2 bond content is 40% or more, and is composed of a block (B) having a main dispersion peak of tan δ at 0 ° C. or higher,
100 parts by weight of a block copolymer having a number average molecular weight of 30,000 to 300,000, and 30 to 10 parts by weight of iron oxide powder
00 parts by weight of a vibration damping composition.