JP2513958C - - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to impact strength, in particular, impact resistance at low temperatures, flowability, and appearance characteristics (
The present invention relates to a polyolefin composition containing a hydrogenated block copolymer having a specific structure excellent in gloss. 2. Description of the Related Art Polyolefin resins are generally used in a wide range of applications, from mechanical parts and automobile parts to household goods and various containers, because of their excellent chemical resistance and mechanical properties. However, the impact strength, particularly at low temperatures, is insufficient, and the intended use may be limited. [0003] 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. Sho 42-19935, Japanese Patent Publication No. Sho 46
JP-8585, JP-B-46-16429 and JP-B-47-26369 disclose, in a polyolefin resin, a styrene-butadiene block copolymer,
It has been shown that the addition of a thermoplastic elastomer improves the impact resistance and stress cracking resistance. However, in these methods, since ordinary block copolymers are used, improvement in impact resistance is not sufficient, and further improvement has been demanded. In addition, the adverse effect of adding a rubber component may cause a decrease in flow processability and a decrease in appearance characteristics, particularly glossiness. For the purpose of improving these points, JP-A-2-158643 using a hydrogenated diene-based random copolymer as a rubber component and JP-A-3-76744 using a block copolymer having a specific molecular weight are disclosed. Have been. However, the composition improved in this way is not sufficient in the low-temperature impact resistance actually required, and further improvement has been demanded. SUMMARY OF THE INVENTION An object of the present invention is to provide an excellent flow resistance which is excellent in impact resistance, particularly practical low-temperature impact resistance and appearance characteristics, and which is suitable for injection molding and extrusion molding. An object of the present invention is to provide an excellent polyolefin composition having processability. Means for Solving the Problems The present inventors have eagerly studied 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 of study, the purpose is achieved by mixing a hydrogenated block copolymer having a specific structure with a polyolefin-based resin in order to obtain a composition having excellent low-temperature impact strength, appearance characteristics, and flowability. This led to the completion of the present invention. That is, the present invention provides: (1) 95 to 50 parts by weight of a polypropylene resin (2) (a) a polymer block A mainly composed of 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 is hydrogenated, and the vinyl bond content before hydrogenation is 40%.
(B) a polymer block C mainly composed of at least one vinyl aromatic compound and at least one conjugate with (b) a hydrogenated block copolymer having a number average molecular weight of 41,000 to 375,000. It has a polymer block D mainly composed of a diene compound, 80% or more of its conjugated diene portion is hydrogenated, and the vinyl bond amount before hydrogenation is 40 to 6
0%, a number average molecular weight of 1,000,000 to 192,000, and a hydrogenated block polymer having a lower molecular weight than that of (a), wherein the ratio of the weight% of (a) and (b) is 40/60. The weighted average of the number average molecular weights (M _N ) of (a) and (b) is 40,000 to 200,
000 (a) molecular weight ratio is from hydrogenated block copolymer 5-50 parts by weight of 1.1 to 4.5 composition (M _N of M _N / (b) of (a)) of (b) Things . In addition, the polyolefin resin shown below means a polypropylene resin.
You. The hydrogenated block copolymer which is the component (2) of the composition of the present invention has a structure of a high molecular weight block copolymer (a) and a low molecular weight block copolymer (b), a vinyl aromatic compound amount, The microstructure such as the amount of vinyl bonds before hydrogenation may be the same or different, as long as it is within the above range. The polymer block A or C mainly composed of a vinyl aromatic compound has a weight ratio of the vinyl aromatic compound to the conjugated diene compound of 100/0 to 51/49, preferably 10/50.
A polymer block having a composition range of 0/0 to 70/30. When a vinyl aromatic compound and a conjugated diene compound are copolymerized, the distribution of the conjugated diene compound in this block is random, tapered (along the molecular chain). And the monomer component may be increased or decreased), partially blocky 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 to the conjugated diene compound is 0/100 to 49/51, preferably 0/100 to 30/70. When a conjugated diene compound and a vinyl aromatic compound are copolymerized, the distribution of the vinyl aromatic compound in this block is random, tapered (the monomer component increases along the molecular chain or Decreasing), partially blocky or any combination thereof. As the vinyl aromatic compound to be provided here, one or two of styrene, α-methylstyrene, alkylstyrene such as p-methylstyrene and p-tert-butylstyrene, paramethoxystyrene, vinylnaphthalene and the like can be used.
At least one species is selected, and among them, styrene and p-methylstyrene are particularly preferred. Examples of the conjugated diene compound include butadiene, isoprene, piperylene, methylpentadiene, phenylbutadiene, 3,4-dimethyl-1,3-hexadiene,
One or more kinds are selected from 5-diethyl-1,3-octadiene and the like, butadiene and / or isoprene are particularly preferred. [0010] The content of the vinyl aromatic compound is preferably in the range of 10 to 50% by weight,
A range of 30% by weight is more preferred. If the content of the vinyl aromatic compound exceeds 50% by weight, the impact resistance of the polyolefin composition may not be improved. If the content is less than 10% by weight, the rigidity tends to be significantly reduced. Become. In the microstructure of the conjugated diene portion, the vinyl bond content before hydrogenation needs to be 40 to 60%, and particularly preferably in the range of 45 to 55%. here,
The vinyl bond content means that 1,2-bond, 3,4-bond and 1,
Among the conjugated diene compounds incorporated in the 4-bond bond mode, the ratio is defined as the ratio of the 1,2- and 3,4-bond conjugated diene compounds. If the vinyl bond content is less than 40%, the impact strength and flow processability at low temperatures are insufficiently improved when the polyolefin composition is used, and if it exceeds 60%, the impact strength at low temperatures becomes low again. It is going down. The microstructure of the conjugated diene moiety is determined by nuclear magnetic resonance (NMR)
). The hydrogenated block copolymer of the present invention is a hydrogenated block copolymer comprising (a) and (b), wherein the component (b) has a lower molecular weight than the component (a), ) / (
It is necessary that the ratio of b) is 40/60 to 90/10 (% by weight). The weighted average of the number average molecular weights of (a) and (b) (40,000 to 200,000)
Range. Also, the ratio of the number average molecular weight of (a) and (b) (M _N / (
_MN ) in b) ranges from 1.1 to 4.5, preferably from 1.2 to 2.2. The number average molecular weight of each of (a) and (b) can be measured by a conventional method using gel permeation chromatography (GPC). The production method is, for example, separately (a
Producing a hydrogenated block copolymer of (b) and a hydrogenated block copolymer of (b),
You may blend. Further, a low molecular weight block copolymer may be subjected to a coupling reaction, the coupling ratio may be controlled within the above range, and hydrogenation may be performed thereafter to produce the copolymer. In the case of a polyolefin composition, the ratio of (a) is 40% by weight.
If it is less than the practical value, the impact resistance at low temperature , the flowability, and the appearance characteristics (gloss)
When the lance is insufficient, and when the lance is 90% by weight or more, the flow processability is reduced, and at the same time, the surface impact strength at low temperature is inferior. In addition, the average number average molecular weight is 40
If it is less than 2,000, the mechanical strength such as tensile strength, including impact resistance, will be low. If it exceeds 200,000, the flow processability will be significantly reduced and the appearance properties will be further inferior. I will. The molecular structure of the block copolymer may be linear, branched, radial, or a combination thereof. Each of the polymer block mainly composed of a vinyl aromatic compound and the block mainly composed of a conjugated diene may have the same structure, the monomer component content, their distribution in the molecular chain, the molecular weight of the block. Each structure such as a micro structure may be different. As a method for producing the block copolymer, for example, JP-B-36-19286,
The methods described in JP-B-43-14979, JP-B-49-36957 and the like can be mentioned. These use an organic lithium compound or the like as an anionic polymerization initiator in a hydrocarbon solvent, an ether compound such as diethyl ether or tetrahydrofuran as a vinylating agent, or triethylamine or N, N, N ', N'-tetramethylethylenediamine. This is a method of block copolymerizing a vinyl aromatic compound and a conjugated diene compound using a tertiary amine, an epoxidized soybean oil as a coupling agent if necessary, and a polyfunctional compound such as silicon tetrachloride. It is obtained as a block copolymer having a branched or radial structure. In the present invention, those obtained by any polymerization method can be used as long as they are those described above. A hydrogenated block copolymer can be obtained by hydrogenating the above block copolymer by a known method, for example, a method described in Japanese Patent Publication No. 42-8704. In the present invention, it is necessary to hydrogenate at least 80% of the conjugated diene portion. If the ratio of hydrogenation is low, the compatibility with the polyolefin resin is insufficient and the impact resistance is low, and the composition is susceptible to thermal deterioration during mixing and molding, which is not preferable. The hydrogenation rate can be analyzed by instrumental analysis using a nuclear magnetic resonance apparatus (NMR). [0016] The hydrogenated block copolymer used in the present invention, denatured by the addition reaction of an unsaturated carboxylic acid or a derivative thereof, can be obtained by containing a functional group.
The hydrogenated block copolymer thus modified is advantageous when painting is required. The polypropylene resin as the component (1) of the composition of the present invention mainly contains propylene.
Any resin may be used as long as it is obtained by polymerization as a body . Among them, polypropylene, an ethylene-propylene block copolymer or a mixture thereof is exemplified. In the polyolefin composition of the present invention, the composition is such that the polyolefin resin of the component (1) is 95 to 50 parts by weight, and the copolymer of the hydrogenated block of the component (2) is 5 to 50 parts by weight, preferably Is 10 to 30 parts by weight. (The component (2) is (a)
And a hydrogenated block copolymer having a lower molecular weight than (a), and the ratio is 40/60 to 90/10. ) When the proportion of the hydrogenated block copolymer is less than 5 parts by weight, the effect of improving the impact resistance, particularly at low temperatures, is not so remarkable. Becomes a low molding material and is not practical. The composition of the present invention can be prepared by an apparatus generally used for mixing high-molecular substances according to the composition ratio of each component. Examples of the mixing device include an extruder, a mixing roll, and a kneader. In the present invention, a melt mixing method using an extruder is particularly preferable. Further, a reinforcing agent or a filler such as calcium carbonate, talc, silica, carbon black, glass fiber, clay or the like can be added to the polyolefin composition of the present invention to such an extent that its properties are not impaired. Further, other additives, for example, a heat stabilizer, an antioxidant, an ultraviolet absorber, a coloring agent, a pigment, and the like may be added. Further, a foaming agent may be added to the composition of the present invention to form a foam. Is also possible. The present invention is a composition comprising a polyolefin-based resin and a hydrogenated block copolymer having a specific structure, and is excellent in impact strength, particularly in impact resistance at low temperature, fluidity, and appearance characteristics. The polyolefin composition of the present invention can be molded by various conventional molding methods, for example, injection molding, extrusion molding, etc., and has a wide range of use in various fields such as molded articles and sheets, and is useful. The composition of the present invention is inexpensive and can be obtained as a product 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 large. EXAMPLES The present invention will be described more specifically and in detail with reference to the following Examples, but the present invention is not limited to these Examples. The measurement standards and test methods of the physical properties shown in Examples and Comparative Examples are as follows. Impact resistance (low temperature) The composition is molded by injection molding to form a sheet having a thickness of 3 mm and a size of 20 cm × 20 cm.
Fix it in a holder at -30 ° C, drop a missile-type weight weighing 13.7 kg from a height of 1.5 m (5.4 m / sec), and determine whether the sheet is brittle or ductile. It was confirmed. [0022] Flowability (MFR) Measured according to JIS K7210. (230 ° C, 2.16 kg load) Surface gloss Measured according to JIS K7105. (Incident angle: 60 °) Flexural modulus Measured according to JIS K7203. (I) Preparation of hydrogenated block copolymer (1) Anionic block copolymerization of styrene and butadiene with n-butyllithium as a polymerization catalyst, tetrahydrofuran as a vinyl content regulator, and styrene and butadiene in a cyclohexane solution. Block copolymers as shown in Nos. 1 and 2 (the unit of the number average molecular weight in Tables 1 and 2 is 10,000) were synthesized. The polymer structure was controlled by charging monomers, the molecular weight was controlled by changing the amount of catalyst, and the vinyl content was controlled by changing the vinyl content regulator . Further, c-1 is diglycidylaniline as a coupling agent after polymerization, c-2 and c-5 are diethyl carbonate, c-3 and c-
In No. 4, a coupling reaction was further performed by adding silicon tetrachloride. The stellene content was measured using an ultraviolet spectrophotometer (UV), the vinyl content was measured using a nuclear magnetic resonance apparatus (NMR), and the number average molecular weight was measured using gel permeation chromatography. (2) Next, each block copolymer was hydrogenated at 5 kg / cm ² using di-p-trisbis (1-cyclopentadienyl) titanium and n-butyllithium as hydrogenation catalysts.
At a temperature of 50 ° C. for 2 hours. The hydrogenation rate (hydrogenation rate) of each sample is shown in the right column of Table 1. Over 90% of the double bonds in the butadiene block were hydrogenated, leaving the benzene ring in the styrene block barely hydrogenated.
Here, c-5 is the same polymer as c-2, in which no hydrogenation reaction was performed. [0024] The hydrogenation rate was measured using a nuclear magnetic resonance apparatus (NMR). (II) Preparation of Polypropylene Composition and Measurement of Physical Properties Commercially available polypropylene (M8619 manufactured by Asahi Kasei Corporation) <MFR = 14 (g / 1)
0))), the obtained hydrogenated block copolymer was added in the proportions shown in Tables 3, 4, 5, and 6, and the mixture was melt-kneaded at a temperature of 220 ° C. with a 30 mm twin-screw extruder, and pelletized It has become. The obtained pellets are injection-molded at 230 ° C. to prepare a sheet and a test piece (a piece of tang), and physical properties such as impact resistance at a low temperature (−30 ° C.), surface gloss, and flexural modulus are measured. did. Tables 3 and 4 show the results of Examples 1 to 9 below. Example 1 A mixture of the hydrogenated block copolymer (a-1) and the diblock-structured low molecular weight hydrogenated block copolymer (b-1) in a ratio of 50/50, 10 parts by weight and 90 parts The physical properties of the composition with parts by weight of polypropylene (M8619) were measured. The impact resistance at low temperatures was excellent, and the fluidity and appearance characteristics were also excellent. Example 2 Example 2 is an example in which a low molecular weight hydrogenated block copolymer (b-2) having a triblock structure was used instead of (b-1). Example 3 Example 1 is an example in which (a-1) is replaced with a hydrogenated block copolymer (a-2) and the blend ratio is 55/45. Embodiment 4 This is an example in which the ratio of (a) / (b) is 75/25 in Embodiment 3. Example 5 This is an example of Example 3, in which the amount of the hydrogenated block copolymer was 20 parts by weight. Sixth Embodiment In the second embodiment, (a-3) is used instead of (a-1). Example 7 Hydrogenated block copolymer (c-1) having a coupling ratio of 75% and a diblock-structured low molecular weight hydrogenated block copolymer having a coupling ratio of <25% using a bifunctional coupling agent Combined / 75% triblock hydrogenated block copolymer> 10 parts by weight and 9
It is an example in which physical properties of a composition of 0 parts by weight of polypropylene were measured. Example 8 In Example 6, a low-molecular-weight diblock structure having a coupling ratio of 72% and a hydrogenated block copolymer (c-2) <28% using a trifunctional coupling agent was used. Hydrogenated block copolymer / hydrogenated block copolymer having a branched structure of 72%>
) Was used instead. Example 9 In Example 6, a low-molecular-weight diblock structure having a coupling ratio of 65% and a hydrogenated block copolymer (c-3) <35% using a tetrafunctional coupling agent was used. Hydrogenated block copolymer / hydrogenated block copolymer having a radial structure of 65%>
Used in place of -1). These examples are all compositions included in the constitution of the present invention, and are excellent in low-temperature impact resistance, appearance properties, and flowability. The superiority of the characteristics becomes deeper by comparing with the following comparative examples. Tables 5 and 6 show the results of Comparative Examples 1 to 8 below. Comparative Example 1 This is an evaluation of polypropylene alone, and has extremely low impact resistance at low temperatures. Comparative Example 2 The physical properties of a composition comprising 10 parts by weight of ordinary hydrogenated block copolymer (a-4) having a triblock structure and 90 parts by weight of polypropylene were measured. Poor impact resistance at low temperature and low fluidity. Comparative Example 3 The hydrogenated block copolymer of Comparative Example 2 was prepared by using (a-4) / (b-3) = 75/25.
The impact resistance and the fluidity have been improved in place of those blended, but they are not satisfactory. This is considered to be due to the low vinyl content of the hydrogenated block copolymer. COMPARATIVE EXAMPLE 4 A composition of a high vinyl hydrogenated block copolymer and a polypropylene was inferior in both low-temperature impact resistance, appearance characteristics, and fluidity. Comparative Example 5 A block copolymer obtained by blending 30% by weight of the hydrogenated block copolymer of Comparative Example 4 with 70% by weight of the low molecular weight hydrogenated block copolymer used in Examples of the present invention. Although it is a composition of coalesced and polypropylene, the impact resistance at a low temperature is remarkably inferior due to a higher ratio of a low molecular weight hydrogenated block copolymer as compared with Examples 3 and 4. Comparative Example 6 A coupling-type hydrogenated block copolymer was used, but the average molecular weight was too high, so that the fluidity and appearance characteristics were reduced, or the impact resistance was also reduced. Was. Comparative Example 7 The same hydrogenated block copolymer as in Example 3 of the present invention was used. However, since the ratio of block copolymerization was large, the flexural modulus was remarkably reduced, which was not practical. Comparative Example 8 The same base polymer as in Example 7 of the present invention was used, but a block copolymer (c-5) without hydrogenation was used, but the impact resistance at low temperatures was poor. Was. [Table 1] [Table 2] [Table 3] [Table 4] [Table 5] [Table 6] The composition of the present invention is a molding material which is excellent in impact strength, particularly excellent in low-temperature impact resistance, flowability and appearance properties, and can be used for daily parts to automobile parts and the like.

Claims (1)

Claims: 1. Claims: (1) 95 to 50 parts by weight of a polypropylene resin (2) (a) at least one conjugated polymer block A containing at least two vinyl aromatic compounds It has a polymer block B mainly composed of a diene compound, 80% or more of its conjugated diene portion is hydrogenated, and the vinyl bond amount before hydrogenation is 4%.
A hydrogenated block copolymer having 0 to 60% and a number average molecular weight of 41,000 to 375,000, and (b) at least one polymer block C mainly composed of a vinyl aromatic compound and at least one polymer block C. It has a polymer block D mainly composed of a conjugated diene compound, and 80% or more of the conjugated diene portion is hydrogenated, and the vinyl bond amount before hydrogenation is 40 to 6
0%, a number average molecular weight of 1,000,000 to 192,000, and a hydrogenated block polymer having a lower molecular weight than that of (a). The weighted average of the number average molecular weights (M _N ) of (a) and (b) is 40,000 to 200,
000 (a) molecular weight ratio is from hydrogenated block copolymer 5-50 parts by weight of 1.1 to 4.5 composition (M _N of M _N / (b) of (a)) of (b) Thing .