JP2513962B2 - Polyolefin composition with excellent impact resistance and heat distortion resistance - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyolefin composition containing a hydrogenated block copolymer having a specific structure which is excellent in impact strength, particularly impact resistance at low temperature, heat distortion resistance and rigidity.

[0002]

2. Description of the Related Art Polyolefin resins are generally used for various purposes such as machine parts, automobile parts, household products and various containers because they are generally excellent in chemical resistance and mechanical properties.
However, the impact resistance strength, especially the impact strength at low temperature, is insufficient, and the purpose of use may be limited.

Therefore, many proposals have been made to add a rubber component to polyolefin for the purpose of improving this problem. For example, Japanese Patent Publication No. 42-19935, Japanese Patent Publication No. 46-8585, Japanese Patent Publication No. 46-16429 and Japanese Patent Publication No. 47-26369 disclose a polyolefin resin, a styrene-butadiene block copolymer,
It has been shown that the addition of thermoplastic elastomers improves impact resistance and stress cracking resistance.

However, since these methods use ordinary block copolymers, the impact resistance is not sufficiently improved. Further, JP-A-2-158643 using a hydrogenated diene random copolymer as a rubber component, and JP-A-3-76744 using a block copolymer having a specific molecular weight.
However, these compositions are not sufficient in the impact resistance at low temperatures actually required, and further improvement has been demanded.

Further, as a harmful effect of adding the rubber component, there is a tendency that the heat distortion resistance is deteriorated and the rigidity is lowered. In particular, heat denaturation is an important property for molded articles, and the birth of a polyolefin composition having both heat denaturation and impact resistance is desired.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a polyolefin composition which is excellent in impact resistance, particularly in practical use, which has a good balance of impact resistance at low temperature, thermal deformation resistance and rigidity.

[0007]

[Means for Solving the Problems] The present inventors have made earnest studies on the correlation between the polymer structure of a hydrogenated product of a vinyl aromatic compound block-conjugated diene compound block copolymer and the physical properties of a polyolefin composition. As a result, it was found that the object can be achieved by mixing a hydrogenated block copolymer having a specific structure with a polyolefin resin in order to obtain a composition excellent in low temperature impact strength and heat distortion resistance. Has been completed.

That is, the present invention provides (1) a polyolefin resin 95 to 50 parts by weight (2) (a) a polymer block A mainly containing at least two vinyl aromatic compounds and at least one conjugated diene compound. Having a polymer block B mainly composed of 80% or more of the conjugated diene portion thereof is hydrogenated, the vinyl bond amount before hydrogenation is 40 to 60%, and the number average molecular weight (hereinafter
(Hereinafter referred to as M _N ) is a hydrogenated block copolymer having a molecular weight of 30,000 to 170,000, and (b) a polymer block C containing at least two vinyl aromatic compounds as a main component and at least one conjugated diene compound as a main component. 80% or more of the conjugated diene portion thereof is hydrogenated, the vinyl bond amount before hydrogenation is 20% or more and less than 40%, and the number average molecular weight is 3
And a hydrogenated block copolymer having a weight ratio of 10,000 to 170,000, wherein the ratio by weight of (a) and (b) is 10/90 to 90/1.
0 Molecular weight ratio of (a) and (b) (M _{N of} (a) / M of (b)
_N ) 0.25 to 4 hydrogenated block copolymer
The polyolefin composition comprises 5 to 50 parts by weight.

The hydrogenated block copolymers (a) and (b) which are the component (2) of the composition of the present invention may have the same structure or the same amount of vinyl aromatic compound, or they may have different amounts. However, it does not matter if it is within the above range. The polymer block A or C mainly containing a vinyl aromatic compound has a weight ratio of the vinyl aromatic compound and the conjugated diene compound of 10 or less.
0/0 to 51/49, preferably 100/0 to 70/3
When the vinyl aromatic compound and the conjugated diene compound are copolymerized in a polymer block having a composition range of 0, the distribution of the conjugated diene compound in this block is random or tapered (the monomer component increases along the molecular chain or Decrease), partial block, or any combination thereof.

In the polymer block B or D mainly composed of a conjugated diene compound, the weight ratio of the vinyl aromatic compound and the conjugated diene compound is 0/100 to 49/51, preferably 0/100 to 30/70. When the conjugated diene compound and the vinyl aromatic compound are copolymerized, the distribution of the vinyl aromatic compound in the block is random or tapered (the monomer component increases along the molecular chain or Decrease), partial block, or any combination thereof. Examples of the vinyl aromatic compound provided here include styrene, α-methylstyrene, p-methylstyrene and p-
One or more selected from alkyl styrenes such as tertiary butyl styrene and the like, paramethoxy styrene, vinyl naphthalene and the like, among which styrene and p-methyl styrene are particularly preferable. Further, as the conjugated diene compound, butadiene, isoprene, piperylene, methylpentadiene, phenylbutadiene, 3,4-dimethyl-
One or more selected from 1,3-hexadiene, 4,5-diethyl-1,3-octadiene, etc.,
Of these, butadiene and / or isoprene are particularly preferable.

The content of vinyl aromatic compound is 10 to 5
The range of 0% by weight is preferable, and the range of 10 to 30% by weight is more preferable. When the content of the vinyl aromatic compound is more than 50% by weight, the impact resistance of the polyolefin composition may not be improved, and when it is less than 10% by weight, the heat distortion resistance and the rigidity are deteriorated. It tends to be remarkable.

The microstructure of the conjugated diene portion of the hydrogenated block copolymer (a) has a vinyl bond content of 40 before hydrogenation.
It is necessary to be up to 60%, and it is particularly preferable to be in the range of 45 to 55%. Here, the vinyl bond amount means 1,2-bond among 1,2-bond, 3,4-bond, and 1,4-bond conjugated diene compounds incorporated in the block copolymer. Percentage of those incorporated by bonds and 3,4-bonds. When the vinyl bond content is less than 40%, the improvement of impact strength at low temperature is insufficient when the composition is made into a polyolefin, and it is 60%.
If it exceeds, the impact strength at low temperature will decrease again.

The microstructure of the conjugated diene portion of the hydrogenated block copolymer (b) has a vinyl bond content of 20 before hydrogenation.
% Or more and less than 40%. Vinyl bond amount is 2
When it is less than 0%, the impact strength of the polyolefin composition is remarkably reduced, and it is 40% as in the case of (a).
When it becomes the above, improvement of heat distortion resistance tends to be insufficient as compared with that of the present invention. The preferred range is 25 to 35
%. The microstructure of the conjugated diene moiety can be analyzed by nuclear magnetic resonance (NMR).

The hydrogenated block copolymer of the present invention is
A hydrogenated block copolymer comprising (a) and (b), wherein the ratio of (a) / (b) is from 10/90 to 90/10.
(% By weight) is required. In the case of a polyolefin composition, if the proportion of (a) is less than 10% by weight, the impact resistance becomes insufficient, and if it exceeds 90% by weight, the heat distortion resistance deteriorates and the impact resistance also decreases. Come on.

The number average molecular weight (M _N ) of (a) and (b) is in the range of 30,000 to 170,000, and the ratio of the number average molecular weight (M _N / (b) of (a)). _MN ) is 0.25
It is in the range of 4, preferably 0.5 to 2. If the molecular weight ratio is outside this range, the balance between impact resistance and heat distortion resistance tends to be poor. The individual number average molecular weights of (a) and (b) can be measured by gel permeation chromatography (GPC) by a conventional method.

The production method may be, for example, to separately produce the hydrogenated block copolymers (a) and (b) and blend them. The molecular structure of the block copolymer may be linear, branched, radial, or a combination thereof, but linear is more preferable. Among the linear chains, those having a structure having at least one polymer block B or D at the end of the polymer chain are particularly preferable in terms of the balance between impact resistance and heat distortion resistance. And, each of the polymer block mainly composed of vinyl aromatic compound or the block mainly composed of conjugated diene may have the same structure, the content of the monomer component, the distribution in their molecular chains, and the molecular weight of the block. Each structure such as a micro structure may be different.

The block copolymer can be produced by, for example, JP-B-36-19286 and JP-B-43-149.
79, Japanese Patent Publication No. 49-36957 and the like. In these, an organic lithium compound or the like is used as an anionic polymerization initiator in a hydrocarbon solvent, an ether compound such as diethyl ether or tetrahydrofuran as a vinylating agent, triethylamine, N,
Tertiary amines such as N, N ', N'-tetramethylethylenediamine, epoxidized soybean oil as a coupling agent, and polyfunctional compounds such as silicon tetrachloride are used as needed, and vinyl aromatic compounds and conjugated diene compounds are used. Is a block copolymer and is obtained as a block copolymer having a linear, branched or radial structure. In the present invention, any polymerization method can be used as long as it is the one described above.

The above block copolymer is prepared by a known method,
For example, a hydrogenated block copolymer can be obtained by hydrogenating according to the method described in JP-B-42-8704. The present invention requires that 80% or more of the conjugated diene moieties be hydrogenated. When the proportion of hydrogenation is low, the compatibility with the polyolefin resin is insufficient and the impact resistance is low, and it is not preferable because it is susceptible to thermal deterioration during mixing and molding. The hydrogenation rate can be analyzed by instrumental analysis using a nuclear magnetic resonance apparatus (NMR).

The hydrogenated block copolymer used in the present invention may be modified by an addition reaction with an unsaturated carboxylic acid or a derivative thereof to contain a functional group.
Modified hydrogenated block copolymers are advantageous when painting is required. The polyolefin resin which is the component (1) of the composition of the present invention is an α-olefin, for example,
Ethylene, propylene, 1-butene, isobutylene, 4
Any resin can be used as long as it is a resin obtained by polymerizing -methyl-1-pentene and the like. Among them, polyethylene, polypropylene, polybutene, polymethylpentene, ethylene-propylene block copolymer or a mixture thereof can be mentioned. Especially preferred is polypropylene.

In the polyolefin composition of the present invention,
Its composition is 95% of the polyolefin resin of component (1).
˜50 parts by weight, 5 to 50 parts by weight, preferably 10 to 30 parts by weight of the copolymer of the hydrogenated block of the component (2). (The component (2) comprises (a) a hydrogenated block copolymer having a vinyl bond content of 40 to 60% before hydrogenation and (b) a vinyl bond content of 20% or more and less than 40% before hydrogenation. It is composed of a hydrogenated block copolymer, and the ratio is 10 / 90-
It is 90/10. ) When the proportion of the hydrogenated block copolymer is less than 5 parts by weight, the effect of improving impact resistance, particularly impact resistance at low temperature, is not so remarkable, and
If it exceeds 50 parts by weight, a molding material having low rigidity and the like becomes unpractical.

The composition of the present invention can be prepared by an apparatus which is usually used for mixing polymer substances depending on the composition ratio of each component. Examples of the mixing device include an extruder, a mixing roll, a kneader, and the like.
In the present invention, the melt mixing method using an extruder is preferable. Also,
To the polyolefin composition of the present invention, it is possible to add a reinforcing agent or a filler such as calcium carbonate, talc, silica, carbon black, glass fiber or clay to the extent that the properties are not impaired. Further, other additives such as a heat stabilizer, an antioxidant, an ultraviolet absorber, a colorant and a pigment may be added, and a foaming agent is further added to the composition of the present invention to form a foam. Is also possible.

The present invention is a composition comprising a polyolefin resin and a hydrogenated block copolymer having a specific structure,
Impact strength, especially impact resistance and heat distortion resistance at low temperature,
Excellent balance of rigidity. The polyolefin composition of the present invention has various conventional molding methods such as injection molding,
It can be molded by extrusion molding or the like, and is useful because it has a wide range of use in various fields such as molded products and sheets.

The composition of the present invention is inexpensive, and a product can be obtained by the above-mentioned ordinary molding method, and can be widely used from daily parts and packaging materials to automobile parts such as automobile interior and exterior parts. The industrial utility value is extremely high.

[0024]

EXAMPLES In order to describe the present invention more specifically and in detail, the following examples are shown, but the present invention is not limited to these examples. The measurement standards and test methods for physical properties shown in Examples and Comparative Examples are as follows. Impact resistance (low temperature) The composition is injection molded to have a thickness of 3 mm, 20 cm x 20 c.
m sheet was molded and fixed to a holder at -30 ° C, and a 13.7 kg weight of a missile type was added to the holder.
It was dropped from a height of 5 m (5.4 m / sec), and it was confirmed whether the sheet was brittle or ductile.

[0025] Heat distortion resistance (HDT) Measured according to JIS K7207. (Load: 4.6 kg
/ Cm ² ) Flexural modulus Measured according to JIS K7203. (I) Preparation of hydrogenated block copolymer (1) By using n-butyllithium as a polymerization catalyst and cyclohexane in solution, tetrahydrofuran as a vinyl content modifier and styrene and butadiene as anion block copolymers, A block copolymer as shown in 1 was synthesized. The polymer structure was controlled by changing the charged amount of the monomer, the molecular weight of the catalyst and the vinyl content of the vinyl content modifier.

The styrene content is measured by an ultraviolet spectrophotometer (U
V), vinyl content, nuclear magnetic resonance (NMR),
The number average molecular weight was measured using gel permeation chromatography. (2) Next, each block copolymer was hydrogenated for 2 hours at a hydrogen pressure of 5 kg / cm ² and a temperature of 50 ° C. using di-p-trisbis (1-cyclopentadienyl) titanium and n-ztillithium as hydrogenation catalysts. I went. The hydrogenation rate (hydrogenation rate) of each sample is shown in the right column of Table 1. 90% or more of the double bonds in the butadiene block portion were hydrogenated, and the benzene ring in the styrene block portion remained almost unhydrogenated. In addition, b-6 is the same polymer as b-2,
The hydrogenation reaction was not performed.

The hydrogenation rate is measured by a nuclear magnetic resonance apparatus (NMR).
It measured using. (II) Preparation of polypropylene composition and measurement of physical properties Commercially available polypropylene (M8619 <M manufactured by Asahi Kasei Corporation)
FR = 14 (g / 10 min)>), the hydrogenated block copolymer obtained was added at a ratio shown in Tables 2 and 3, and 30 m
Melt kneading was carried out at a temperature of 220 ° C. by a twin-screw extruder of m to pelletize.

The obtained pellets were injection-molded at 230 ° C. to prepare a sheet and a test piece (tanzaku piece), and the impact resistance at low temperature (−30 ° C.), heat distortion resistance, and flexural modulus were measured. The results of Examples 1 to 9 below are shown in Table 2.

[0029]

Examples 1 to 9 Hydrogenated block copolymers (a) and (b) were blended according to the formulations shown in Table 2, and polypropylene (M8619) was further added to prepare compositions.
These were compositions which were excellent in impact resistance at low temperatures and thermal deformation resistance, and also excellent in rigidity. The above-mentioned examples are all examples of compositions included in the constitution of the present invention, and are polyolefin compositions having excellent properties. The superiority of the properties will become more apparent by comparing with the following comparative examples (Table 3). Also, the effect of defining the structure is clear.

The results of the following Comparative Examples 1 to 9 are shown in Table 3.

[0031]

Comparative Example 1 Evaluation of polypropylene alone, which shows extremely low impact resistance at low temperatures.

[0032]

Comparative Examples 2 and 3 Single hydrogenated block copolymer (a
-1) or (b-1) The physical properties of a composition of 10 parts by weight and 90 parts by weight of polypropylene were measured. It is inferior in impact resistance at low temperatures.

[0033]

Comparative Example 4 Hydrogenated block copolymers (a) and (b)
It is an example of what the amount ratio of was outside the scope of the present invention,
Poor impact resistance at low temperature.

[0034]

[Comparative Example 5] This is an example in which the molecular weight of the hydrogenated block copolymer used was outside the range of the present invention, but the impact resistance was poor.

[0035]

Comparative Example 6 Hydrogenated block copolymers (a) and (b)
The molecular weight ratio of is outside the range of the present invention, but the impact resistance is lowered, and the heat distortion resistance and rigidity are also poor.

[0036]

Comparative Example 7 Block copolymer (b) not hydrogenated
-6) was used, but the impact resistance at low temperature is poor.

[0037]

[Comparative Example 8] This is an example in which the vinyl content of the hydrogenated block copolymer before hydrogenation was outside the range of the present invention.
It has poor impact resistance at low temperatures.

[0038]

[Comparative Example 9] The same hydrogenated block copolymer as in Example 2 of the present invention was used. However, since the ratio of the block copolymer is covered, the heat distortion resistance and the rigidity are remarkably lowered, which is not practical.

[0039]

[Table 1]

[0040]

[Table 2]

[0041]

[Table 3]

[0042]

INDUSTRIAL APPLICABILITY The present invention is a composition comprising a polyolefin resin and a hydrogenated block copolymer having a specific structure, and is excellent in impact resistance, particularly impact resistance at low temperature, heat distortion resistance, and rigidity. ing. The composition of the present invention is
It is inexpensive and can be obtained by ordinary molding methods such as injection molding and extrusion molding, and it can be widely used from daily parts and packaging materials to automobile parts such as automobile interior and exterior parts. Is extremely large.

Claims (1)

(57) [Claims] (1) Polyolefin resin 95 to 5
0 part by weight (2) (a) having at least two vinyl aromatic compound-based polymer blocks A and at least one conjugated diene compound-based polymer block B, 80% or more is hydrogenated, the vinyl bond amount before hydrogenation is 40 to 60%, the number average molecular weight (hereinafter
(Hereinafter referred to as M _N ) is a hydrogenated block copolymer having a molecular weight of 30,000 to 170,000, and (b) a polymer block C containing at least two vinyl aromatic compounds as a main component and at least one conjugated diene compound as a main component. 80% or more of the conjugated diene portion thereof is hydrogenated, the vinyl bond amount before hydrogenation is 20% or more and less than 40%, and the number average molecular weight is 3
And a hydrogenated block copolymer having a weight ratio of 10,000 to 170,000, wherein the ratio by weight of (a) and (b) is 10/90 to 90/1.
0 Molecular weight ratio of (a) and (b) (M _{N of} (a) / M of (b)
_N ) 0.25 to 4 hydrogenated block copolymer
A polyolefin composition comprising 5 to 50 parts by weight.