JP2790313B2 - Polypropylene composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a polypropylene composition having excellent vibration damping performance.

[Prior Art] In recent years, the use of plastic materials as housings, interior and exterior materials for various devices including office equipment, audio equipment, and home electric appliances has become common. Among them, polypropylene is one of the most widely used materials because of its relatively low cost and excellent moldability. In applications where this is used, for example, in office equipment such as copiers and printers, reduction of noise and vibration generated from these is 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.

[Problems to be Solved by the Invention] A polymer material is originally an advantageous material from the viewpoint of suppressing the generation of vibration and noise as compared with a metal material. It was not satisfactory in terms of noise.

The present inventors have conducted intensive studies on a polypropylene-based material that satisfies the above requirements, and found that a composition comprising polypropylene and a styrene-isoprene-based block copolymer having a specific molecular structure can solve the above object. And found the present invention.

[Means for Solving the Problems] According to the present invention, the above-mentioned problems can be solved by (a) polypropylene 97
(B) a block (A) composed of a vinyl aromatic monomer having a number average molecular weight of 2500 to 40,000, and isoprene or an isoprene-butadiene mixture having a number average molecular weight of 10,000 to 200,000, 3.4 times bonding and 1.2 A block copolymer comprising a block (B) having a bond content of 40% or more and having a main dispersion peak of tan δ at 0 ° C. or more and having a number average molecular weight of 30,000 to 300,000, or a hydrogenated copolymer thereof This is achieved by a composition comprising 3 to 50 parts by weight of the product.

The present composition can be used as a material in which the generation of vibration and noise is reduced without impairing the excellent moldability of polypropylene.

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

As the polypropylene used in the present invention,
In addition to a homopolymer of propylene, a copolymer of propylene and another α-olefin such as ethylene, and a modified polypropylene having a carboxyl group or the like may be used. In this case, the form of copolymerization may be either block or random. As the polypropylene, those having a melt flow rate (MFR) in the range of approximately 0.01 to 100 are preferably used.

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

The number average molecular weight of the vinyl aromatic block (A) is 2500-
It is in the range of 40000. When the molecular weight is less than 2500, the performance as a composition is reduced, and when it exceeds 40,000, the melt viscosity becomes too high, and mixing with polypropylene does not work well, and a composition having sufficient performance cannot be obtained.

The ratio of the vinyl aromatic block (A) in the block copolymer depends on the mechanical properties of the block copolymer,
From the viewpoints of viscosity and vibration damping performance, it is preferably in the range of 5% by weight to 50% by weight.

It is preferable to use isoprene or isoprene-butadiene in combination as the second component of the block copolymer used in the present invention. When other monomers are used, for example, in the case of butadiene alone, the temperature at which the damping performance is exhibited even if the 1.2 bond content is increased is less than 0 ° C., and the damping performance at the temperature actually used is Not obtained and has little practical significance. In the case of isoprene, the 3.4 bond and 1.2 bond content of the present invention (hereinafter sometimes collectively referred to as vinyl bond content),
Vibration damping performance can be exhibited in a practical temperature range from about 0 ° C. to about 50 ° C., and it can be used in a wide range of applications, which is extremely significant in practical use. When isoprene-butadiene is used in combination, if the proportion of isoprene is 40% or more, it exhibits vibration damping performance at 0 ° C or more. Isoprene
When butadiene is used in combination, the form of the block (B) may be any of random, block or tapered.

The block copolymer (B) of the present invention has a content of 3.4 bonds and 1.2 bonds of 40% or more (or 100%). If the vinyl bond content 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 vinyl bond amount of the isoprene block is 100%, the absorption temperature of tan δ is about 60 ° C., so the possible upper limit is about 60 ° C.

The number average molecular weight of the block (B) is 10,000 to 20,000.
A range of 0 is used. When the molecular weight is smaller than the above range, it is not preferable that the elastic properties are not deteriorated. On the other hand, if it is too large, the fluidity becomes poor, which is not preferable.

The number average molecular weight of the obtained block copolymer is 30,000 to 3
Must be in the range of 00000. If the molecular weight is less than 30,000, the mechanical properties such as strength at break and elongation at break of the block copolymer itself are reduced, and when the composition is used as a composition, the strength is undesirably reduced. Also, if it exceeds 300,000, the processability becomes worse, mixing with polypropylene does not work well,
A composition having sufficient performance cannot be obtained. From this point, the molecular weight of the block copolymer is more preferably 80,000 to 25,000.
It should be in the range of 0.

The block form of the block copolymer used in the present invention is represented by A (BA) n, (AB) n. Here, A represents a block composed of an aromatic vinyl monomer, B represents a block composed of isoprene or isoprene-butadiene, and n
Is an integer of 1 or more. Of these, the ABA form is most preferably used.

In the isoprene or isoprene-butadiene block, part or all of the carbon-carbon double bond in the block is hydrogenated as necessary. The hydrogenation rate is determined according to the required level of heat resistance and weather resistance, but is usually 50% or more, preferably 70% or more, and 80% when higher heat resistance and weather resistance are required. % Or more are used. If the degree of hydrogenation is less than 50%, the effect of improving heat resistance and weather resistance cannot be obtained.

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

First, a block copolymer is produced by (a) a method of 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. Or (c) using a dilithium compound as an initiator to prepare isoprene or isoprene-
A method in which butadiene and then an aromatic vinyl compound are sequentially polymerized is exemplified.

Examples of the alkyl lithium compound include an alkyl compound having 1 to 10 carbon atoms in the alkyl residue,
Particularly, methyl lithium, ethyl lithium, pentyl lithium and butyl lithium are preferred. As the coupling agent, dichloromethane, dibromomethane, dichloroethane, dibromoethane, dibromobenzene and the like are used. Examples of the dilithium compound include naphthalenedilithium, dilithiohexylbenzyl and the like. The amount used is determined by the molecular weight to be determined, but generally about 0.0 parts by weight of initiator based on 100 parts by weight of all monomers used for polymerization.
It is used in the range of about 1 to 0.2 part by weight and about 0.04 to 0.8 part by weight of the coupling agent.

As a microstructure of isoprene or isoprene-butadiene part, the vinyl bond is tanned at 40% or more and at 0 ° C or more.
A Lewis base is used as a co-catalyst in the polymerization of isoprene or isoprene-butadiene to have a peak of the main dispersion of δ. Examples of Lewis bases include ethers such as diethyl ether, diethyl ether and tetrahydrofuran, glycol ethers such as ethylene glycol dimethyl ether and diethylene glycol dimethyl ether, triethylamine, N, N, N ', N'-
Examples include amine compounds such as tetramethylethylenediamine (TMEDA) and N-methylmorpholine. These Lewis bases are used in an amount of about 0.1 to 1000 times the mole number of lithium in the polymerization catalyst.

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 as necessary. A method in which molecular hydrogen is reacted with a known hydrogenation catalyst in a state of being dissolved in a solvent which is the same as or different from the solvent used during the polymerization, and which is inert to the hydrogenation reaction and the hydrogenation catalyst, is preferable. Used. The catalyst used is Raney nickel or P
From heterogeneous catalysts such as those in which metals such as t, Pd, Ru, Rh, and Ni are supported on a simple substance such as carbon, alumina, and diatomaceous earth, or from a combination of a transition metal and an alkyl aluminum compound or an alkyl lithium compound Ziegler catalysts and the like are 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.

The degree of hydrogenation is determined by the required level of the physical properties. When importance is placed on heat resistance and weather resistance, the degree of hydrogenation is preferably 50% or more, preferably 70% or more.

After the reaction, the block copolymer is heated or dried under reduced pressure after the reaction solution is coagulated 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 composition of the present invention comprises 97 to 50 parts by weight of polypropylene,
The block copolymer is contained in a range of 3 to 50 parts by weight. If the ratio of the block copolymer is less than this, the obtained composition has insufficient vibration damping performance, and if it is too large, the composition softens and loses its properties as a plastic, which is not suitable for the intended use of polypropylene. It is not desirable.

The composition according to the present invention contains polypropylene and a block copolymer as essential components, and is used by blending various additives as necessary. Examples thereof include 20 to 250 parts by weight of a reinforcing agent such as carbon black, silica, calcium carbonate, and mica, and fillers, and 0.01 to 5 parts by weight of an antioxidant and an ultraviolet absorber. Of these, mica is particularly preferably used because it improves vibration damping performance. In the case of adding mica, by using the amount of 20 parts by weight or more, more preferably 40 parts by weight or more, it becomes possible to exhibit higher vibration damping performance.

In some cases, other polymers can be blended and used to the extent that the gist of the present invention is not impaired. Examples thereof include polyethylene, polystyrene, atactic polypropylene, polybutene, EPR, styrene-conjugated diene block copolymer or hydrogenated product thereof, and ethylene-vinyl acetate copolymer. The blending ratio of these polymers is preferably about 30% by weight or less based on the block copolymer.

The composition according to the present invention is used by kneading and molding polypropylene and a block copolymer by a kneader, an extruder, an injection molding machine or the like. The resulting composition comprises office equipment,
It is suitably used for housings, inner and outer materials of automobiles, inner and outer materials for automobiles, outer materials, bumpers and the like, including audio equipment and household electric appliances.

[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.

Microstructure measured NMR spectrum, 4.8 ppm, 5.8 ppm
From the ratio of the peak of 3.4 bond and 1.2 bond to the peak of 1.4 bond of 5.3 ppm, the content of 3.4 bond and 1.2 bond was calculated.

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 value of tan δ at 25 ° C. was determined as an index of the damping performance.
A larger value indicates better damping.

Reference Example In a pressure-resistant reactor that was dried and replaced with nitrogen, cyclohexane was used as a solvent, n-butyllithium was used as a polymerization catalyst, TMEDA was used as a vinylating agent, and a styrene monomer, an isoprene monomer, and a styrene monomer were added in this order and polymerized.
The obtained ABA type copolymer in cyclohexane,
A hydrogenation reaction was carried out at a hydrogen pressure of 20 kg / cm ² using Pd—C as a hydrogenation catalyst to obtain block copolymers (I), (II) and (III) having the molecular characteristics shown in Table 1.

The block copolymers obtained in Examples 1 to 7 and Comparative Examples 1 and 2 were mixed with polypropylene by Brabender according to the formulation shown in Table 2 for 220.
A composition was prepared by kneading at ℃.

The obtained composition was press-molded at 220 ° C. to form a 2 mm sheet, and tan δ at 25 ° C. was measured.

For comparison, polypropylene alone and a styrene-isoprene-styrene block copolymer having a small amount of vinyl bond with polypropylene (SIS, TR-1107, vinyl bond amount of 12
%; Manufactured by Shell Chemical Co., Ltd.) was also measured for tan δ.

The results are shown in Table 2. From these results, it is understood that the composition of the present invention has an excellent vibration damping effect.

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C08L 23/00-23/36 C08L 53/02

Claims (1)

(57) [Claims] 1. A composition comprising (a) 97 to 50 parts by weight of polypropylene, and (b) a block (A) comprising a vinyl aromatic monomer having a number average molecular weight of 2500 to 40,000, and isoprene or an isoprene-butadiene mixture, Number average molecular weight is 10,000 to 200,000, 3.4 bond and 1.2 bond content is 4
0% or more and composed of a block (B) having a main dispersion peak of tan δ at 0 ° C. or more, having a number average molecular weight of 30
A polypropylene composition comprising a block copolymer of 000 to 300,000 or a hydrogenated product thereof in an amount of 3 to 50 parts by weight.