JP2703335B2 - Polymer and composition having excellent vibration damping properties - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a novel block copolymer excellent in vibration damping performance, heat resistance and weather resistance, and a composition using the same.

[Prior Art] In recent years, with the development of transportation such as automobiles, noise and vibration resulting therefrom have become a serious social problem. In addition, high demands for low vibration and low noise have been demanded inside the automobile. In addition, office equipment such as copiers and printers are also widely used in ordinary households, and reduction of noise and vibration generated by these equipment has become an important issue. Furthermore, household appliances are becoming larger due to changes in lifestyles, and low vibration and low noise of appliances with vibration, such as refrigerators, washing machines, and vacuum cleaners, are also important in terms of quiet performance as a product. It is one.

Conventionally, various springs, vibration-proof rubbers, and the like have been used to reduce the vibration and noise, but cannot meet the various requirements described above. This method is to reduce the generation of vibration and noise by interrupting the transmission of vibration. In addition to this, a method called vibration suppression, which suppresses vibration itself, has become widespread.
This is a method of sticking or sandwiching various viscoelastic bodies to a vibrating object to suppress the occurrence of vibration. As vibration damping materials used for this purpose, polyester-based (JP-A-62-295949), polyamide-based (JP-A-56-159160) and epoxy resin-based (JP-B-58-23426) have been used. Gazettes) have been proposed.

However, these require complicated operations during molding and construction, such as using a solution of an organic solvent, molding a fluid compound by casting, and bonding a molded product using an adhesive. However, there were cases where safety and health issues became a problem. Also, the obtained vibration damping material must have good adhesiveness with the target equipment when used, and have sufficient moldability when molded after bonding. Must also exhibit sufficient elasticity. At present, there is no material that has sufficient vibration damping performance and satisfies all of the workability during construction and the moldability after bonding.

[Problems to be Solved by the Invention] The present inventors have conducted intensive studies on materials satisfying the above-mentioned requirements, and have found that a block composed of a diene-based monomer having a certain microstructure and a block composed of an aromatic vinyl-based monomer. Has been found to be an excellent material for vibration damping materials having the above properties (Japanese Patent Application No. 63-254657).

However, since such a block copolymer has a carbon-carbon double bond in its molecular chain, it has been found that there may be a problem in heat resistance and weather resistance. Have led to the present invention.

[Means for Solving the Problems] According to the present invention, the above-mentioned problems are caused when the number average molecular weight is 2500 to 40.
Block consisting of 000 vinyl aromatic monomers (A)
And isoprene or an isoprene-butadiene mixture, having a number average molecular weight of 10,000 to 200,000, 3.4 bonds and
1.2 having a main dispersion peak of tan δ at 0 ° C. or higher at a bond content of 40% or higher and comprising a block (B) in which at least a part of the carbon-carbon double bond in the chain is hydrogenated; The form of the connection of the blocks is A- (BA) n, or (A-
B) A molecular weight represented by n (n is an integer of 1 or more) having a molecular weight of 3000
The problem is solved by a block copolymer of from 0 to 300,000 and by a composition comprising said block copolymer.

This block copolymer shows sufficient strength properties without cross-linking reaction because the vinyl aromatic block (A) forms a pseudo cross-linking point, and at least a part of the carbon-carbon double bond is hydrogenated. (B), which is made of isoprene or an isoprene-butadiene mixture, has excellent elasticity and therefore has sufficient moldability even when molded after lamination. The block copolymer has thermoplasticity and can be molded by hot melt, and is extremely easy to mold.

 Hereinafter, the present invention will be described in more detail.

As the first component of the block copolymer used in the present invention, an aromatic vinyl monomer, for example, styrene,
α-methylstyrene, 1-vinylnaphthalene, 2-vinylnaphthalene, 3-methylstyrene, 4-propylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2-ethyl-4-benzylstyrene, 4- (phenylbutyl) There are styrene and the like, and most preferred is styrene.

As the second component of the block copolymer used in the present invention, isoprene or a combination of isoprene and butadiene is suitable. When other monomers are used, for example, in the case of butadiene alone, 1.2
0 ° C at which the vibration damping performance is exhibited even if the bond content is increased
Is less than the above, the vibration damping performance at the temperature actually used cannot be obtained, and the practical significance is small. In the case of isoprene, by setting the content of 3.4 bonds and 1.2 bonds of the present invention, it is possible to exhibit vibration damping performance in a practical temperature range from about 0 ° C. to about 50 ° C., and to support a wide range of applications. Is possible, and is extremely significant in practical use. When isoprene and butadiene are used in combination, if the proportion of isoprene is 40% or more, the damping performance is exhibited at 0 ° C or more. The form of the block (B) may be any of random, block, and tapered.

3. of the block portion of the present invention comprising the block copolymer isoprene or a mixture of isoprene and butadiene.
The content of 4 bonds and 1.2 bonds is 40% or more (may be 100%)
It is necessary to be. 3.4 bond and 1.2 bond content
If it is less than 40%, sufficient vibration damping performance cannot be obtained in a normal operating temperature range, which is not preferable.

It can also be obtained by measuring the viscoelasticity of the block copolymer.
It is necessary that the temperature of the peak of the main dispersion of tan δ (loss tangent) is 0 ° C. or higher. If there is only a peak at a temperature lower than 0 ° C., sufficient vibration damping performance cannot be obtained in a normal temperature range. When the 3.4 and 1.2 bond content of the isoprene block is 100%, the absorption temperature of tan δ is about 6
Since the temperature is 0 ° C., the possible upper limit is about 60 ° C.

The molecular weight of the vinyl aromatic block is in the range of 2500 to 40,000. If the molecular weight is smaller than 2500, the mechanical properties decrease, and if it exceeds 40,000, the melt viscosity becomes too high and the thermoplasticity is impaired.

The block composed of the isoprene or the isoprene-butadiene mixture requires that at least a part of the carbon-carbon double bond in the block be hydrogenated. The hydrogenation rate is determined according to the required heat resistance and weather resistance level, but is usually 50 mol% or more, preferably 70 mol% or more, and when higher heat resistance and weather resistance are required. Is 80
Those having a hydrogenation rate of at least mol% are used.

The proportion of the block (A) composed of vinyl aromatic in the block copolymer is in the range of 5% by weight to 50% by weight. When the proportion of the block (A) is less than 5% by weight, the mechanical properties of the block copolymer become insufficient, and when it exceeds 50% by weight, the viscosity becomes extremely high, so that processing becomes difficult, and vibration damping performance is increased. Also decrease.

The molecular weight of the obtained block copolymer is 30,000 to 300,000.
Must be in the range of If the molecular weight is less than 30,000, the mechanical properties such as strength at break and elongation of the block copolymer itself are reduced. On the other hand, if it exceeds 300,000, workability deteriorates. From this point, the molecular weight of the block copolymer is 80.
It is preferably in the range of 000 to 250,000.

The block form of the block copolymer of the present invention is A (B
A) n and (AB) n are used. Where n
Is an integer of 1 or more, and the upper limit thereof is not particularly limited, but is preferably about 20 or less.

The block copolymer of the present invention can be obtained by the following various methods.

First, the polymerization of the block copolymer is carried out by sequentially polymerizing an aromatic vinyl compound, isoprene or an isoprene-butadiene mixture using an alkyllithium compound as an initiator, or polymerizing an aromatic vinyl compound and then isoprene or an isoprene-butadiene mixture. Or a method of sequentially polymerizing isoprene or an isoprene-butadiene mixture and then an aromatic vinyl compound using a dilithium compound as an initiator. Examples of the alkyl lithium compound include an alkyl compound having 1 to 10 carbon atoms in the alkyl residue.
Ethyl lithium, pentyl lithium, and butyl lithium are preferred. As the coupling agent, dichloromethane, dibromomethane, dichloroethane, diuromoethane, dibromobenzene and the like are used. Examples of the dilithium compound include naphthalenedilithium and dilithiohexylbenzene. The amounts of these initiators and coupling agents used are determined by the molecular weight to be determined.
It is used in the range of about 4 to 0.8 parts by weight.

In order to make the microstructure of block (B) from isoprene or an isoprene-butadiene mixture to have 3.4 or 1.2 bonds of 40% or more and to have a main dispersion peak of tan δ at 0 ° C or more, isoprene or isoprene- A Lewis base is used as a cocatalyst during the polymerization of the butadiene mixture. 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 (TMEDA), N- Examples include amine compounds such as methylmorpholine. The amount of these Lewis bases used is generally about 0.1 to the number of moles of lithium in the polymerization catalyst.
Used in the range of ~ 1000 times.

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

The polymerization is carried out in any of the polymerization methods at a temperature in the range of 0 to 80 ° C. for 0.5 to 50 hours.

The obtained block copolymer is hydrogenated by a known method. A method in which molecular hydrogen is reacted with a known hydrogenation catalyst in a state of being dissolved in a solvent inert to the hydrogenation reaction or the hydrogenation catalyst is preferably used. As the catalyst used, Raney nickel, or a heterogeneous catalyst such as a metal such as Pt, Pd, Ru, Rh, Ni supported on a simple substance such as carbon, alumina, and diatomaceous earth, or a transition metal A Ziegler-based catalyst composed of a combination of an alkylaluminum compound, an alkyllithium compound and the like is used. The reaction is carried out at a hydrogen pressure of normal pressure to 200 kg / cm ² , a reaction temperature of normal temperature to 250 ° C., and a reaction time of 0.1 to 100 hours.

After the reaction, the block copolymer is heated or dried under reduced pressure after coagulating the reaction solution with methanol or the like,
It is obtained by pouring the reaction solution into boiling water, removing the solvent by azeotropic distillation, and then heating or drying under reduced pressure.

The block copolymer of the present invention has thermoplasticity, can be molded by hot melt, and has excellent processability. That is, a method of melt-kneading with a kneader or the like under heating and coating under melting or molding by a press or the like, a method of molding by an extruder, or the like is used. In any of these methods, a reaction such as crosslinking is not required, and a molded product exhibiting sufficient strength properties can be obtained by cooling after molding.

The block copolymer according to the present invention is used by blending various compounding agents as necessary. Examples include tackifying resins such as rosin, terpene, and petroleum resins, plasticizers such as DOP, DOA, and process oil; reinforcing agents such as carbon black, silica, calcium carbonate, and mica; fillers, and coloring agents. Can be Of these, mica is particularly preferably used because it improves vibration damping performance. The use amount of these compounding agents is preferably 10 to 300 parts by weight for the tackifier resin, 20 to 250 parts by weight for the reinforcing agent and the filler, and 20 parts by weight or more for mica.

In some cases, other polymers can be blended and used to the extent that the gist of the present invention is not impaired. In this case, styrene-ethylenebutylene-styrene block copolymer, styrene-ethylenepropylene-styrene block copolymer, styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, ethylene-vinyl acetate copolymer Polymers and the like are more preferably used. The blending ratio of these polymers is preferably used at 30% by weight or less based on the block copolymer.

The block copolymer and the composition of the present invention can be applied as they are as a molded product or to a metal or plastic plate,
It is used in the form of pinching.

The block copolymer according to the present invention can be used as a base or blended with various plastics. Examples of particularly preferred plastics include polyolefins, polyamides, styrene-based plastics, polyesters, ABS-based plastics, and polycarbonates. The blending ratio of these materials to plastics is preferably about 50% by weight or less. Blending with these plastics is performed by a usual method. By blending the block copolymer according to the present invention with various plastics, it becomes possible to impart vibration damping performance to them and it is preferably used for housings, various parts and the like.

[Examples] Hereinafter, the present invention will be described more specifically with reference to Examples.

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

 The molecular weight was determined by GPC.

The microstructure was measured by NMR spectrum, δ 4.8 ppm, δ
5.8 ppm peaks at 3,4 and 1.2 bonds and δ 5.3 ppm at 1
The content of 3,4 bonds and 1.2 bonds was calculated from the ratio of the peaks of the 4 bonds.

The hydrogenation rate was calculated from the ratio of the iodine values of the block copolymer before and after the hydrogenation reaction.

The peak temperature of tan δ was determined by measuring a viscoelastic spectrum with Leo Vibron (manufactured by Orientec).

The loss coefficient (η) indicating the vibration damping performance was determined by a resonance method in which a specimen obtained by applying a compound to a steel sheet having a thickness of 1 mm was vibrated by a vibrator to measure the degree of resonance of the specimen. The measurement was performed at a measurement frequency of 500 Hz and a measurement temperature of 25 ° C.

Example 1 600 ml of cyclohexane as a solvent and 0.2 ml of n-BuLi as a polymerization catalyst were placed in a pressure-resistant reactor which had been dried and replaced with nitrogen.
After adding 0.2 ml of TMEDA to the vinylating agent and raising the temperature to 50 ° C,
A styrene monomer (5 ml), an isoprene monomer (120 ml), and a styrene monomer (5 ml) were added in this order and polymerized. The copolymer was recovered by treating the polymerization solution with methanol, and the copolymer was dissolved in 500 ml of cyclohexane.
C (5% Pd) was added at 5%, and a hydrogenation reaction was performed at 150 ° C. under a hydrogen pressure of 20 kg / cm ² . After the reaction, the catalyst was removed by filtration, followed by vacuum drying to obtain a block copolymer (I).

The molecular weight of the obtained polymer was 175,000, the molecular weight of the polystyrene block was 10,000, the molecular weight of the polyisoprene block was 150,000, the total amount of 3.4 and 1.2 bonds was 79.8%, and the hydrogenation ratio was 91.5%.

 The peak temperature of tan δ was 39.8 ° C.

Example 2 A block copolymer (II) was obtained by polymerizing and hydrogenating 7 ml of a styrene monomer, 150 ml of an isoprene monomer and 7 ml of a styrene monomer in this order in the same manner as in Example 1.
I got Its molecular weight was 120,000, the molecular weight of the polystyrene block was 8,000, the molecular weight of the polyisoprene block was 100,000, the total amount of 3.4 and 1.2 bonds was 73.4%, and the hydrogenation ratio was 78.2%. The peak temperature of tan δ was 36.8 ° C.

Example 3 0.5 ml of n-BuLi and 0.25 ml of TMEDA as a vinylating agent
The polymerization and hydrogenation were carried out in the same manner as in Example 1 except that the block copolymer (II) was obtained. It has a molecular weight of 86,000 and a polystyrene block of 500.
The molecular weight of the polyisoprene block was 75,000, the total amount of 3.4 bonds and 1.2 bonds was 59.6%, and the hydrogenation rate was 63.1%. t
The peak temperature of anδ was 25.7 ° C.

Example 4 The block copolymer (I) obtained in Examples 1 to 3,
Using (II) and (III), a resin composition was prepared according to the formulation shown in Table 1, and a loss coefficient at ordinary temperature was measured in order to evaluate the damping performance of the obtained composition.

 The results are shown in Table 1.

As is clear from this, it is found that the block copolymer and the composition thereof according to the present invention have excellent vibration damping performance at 25 ° C.

Comparative Example 1 A block copolymer (IV) polymerized in the same manner as in Example 1 and obtained without hydrogenation [molecular weight 176,000, molecular weight of polystyrene block 10,000, molecular weight of polyisoprene block
151000, vinyl bond amount 79.9%], prepare a 2 mm thick sheet, heat it in an oven at 200 ° C for 30 minutes, measure the strong elongation before and after heating, and evaluate the heat degradation behavior. Was evaluated. Table 2 shows the results. Table 2 also shows the results of the same evaluation of the heat deterioration resistance of the block copolymer (I) obtained in Example 1.

From the results shown in Table 2, the physical properties of the non-hydrogenated block copolymer (IV) are largely reduced, whereas the physical properties of the block copolymer (I) of the present invention are almost changed. It can be seen that it is excellent in heat deterioration resistance.

Claims (2)

(57) [Claims] 1. A block (A) comprising a vinyl aromatic monomer having a number average molecular weight of 2,500 to 40,000 and isoprene or an isoprene-butadiene mixture having 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, has a main dispersion peak of tan δ at 0 ° C. or more, and is constituted by a block (B) in which at least a part of carbon-carbon double bonds in the chain is hydrogenated. A block copolymer having a molecular weight of 30,000 to 300,000, whose form is represented by A- (BA) n or (AB) n (n is an integer of 1 or more). 2. A composition comprising the block copolymer according to claim 1.