JPH0730145B2 - Propylene block copolymer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a propylene block copolymer, and more specifically, it is remarkably excellent in mechanical properties such as impact resistance (particularly surface impact resistance) and rigidity. The present invention relates to a propylene block copolymer that can be suitably used in the fields of electric appliances, home appliances, automobile materials and the like.

[Conventional technology]

A propylene-ethylene copolymer that is commercially available as a so-called propylene block copolymer is used as a resin having excellent impact resistance, rigidity, and the like, in various industrial fields such as automobiles, home appliances, large sundries, and the like. . In recent years, as its applications have expanded and the products have become thinner, the required properties have become more sophisticated, and it is desired to have a quality that further improves impact resistance while maintaining high fluidity and high rigidity. Is becoming. With regard to impact resistance, not only Izod impact values but also those with excellent surface impact resistance are demanded.

As a method for obtaining a propylene polymer composition such as a conventional propylene block copolymer, a method of blending polyethylene with a propylene copolymer (JP-A-55-58245, JP-A-57-137341), A method of producing a propylene block copolymer by a two-stage polymerization method (Japanese Patent Laid-Open No. 56-55416) and the like have been proposed. However, the propylene polymer composition obtained by any of the methods has impact resistance, In particular, there are drawbacks that the surface impact resistance when thinning is not sufficient, and the balance of mechanical properties such as impact resistance, rigidity and fluidity, and workability is poor. In order to address these drawbacks, a propylene-ethylene block copolymer having a low melt index value is pyrolyzed in the presence of a peroxide to improve fluidity, thereby improving the balance of properties. To improve the (Japanese Patent Publication Sho 58-7665
However, there is a problem that the polymer composition obtained by this method is still insufficient in impact resistance, particularly in terms of physical property balance between surface impact resistance and rigidity. It was

[Problems to be solved by the invention]

The present invention intends to provide a propylene block copolymer which is excellent in impact resistance such as surface impact resistance and which is excellent in various properties such as rigidity and fluidity, which solves the conventional problems. .

[Means for solving problems]

As a result of various studies based on the above circumstances, the present inventors have found that a specific crystalline polypropylene part and a specific ethylene-
Propylene block copolymer containing a specific proportion of propylene copolymer, while maintaining high flow and high rigidity,
Moreover, they have found that they are remarkably excellent in impact resistance such as surface impact resistance, and have completed the present invention.

That is, the propylene block copolymer of the present invention is a propylene block copolymer containing a crystalline polypropylene part [component (a)] and an ethylene-propylene random copolymer [component (b)]. When the total amount of the component (a) and the component (b) is 100% by weight, the content of the component (a) is 55 to 95% by weight and the content of the component (b) is 5 to 45% by weight. When the intrinsic viscosities of the component (a) and the component (b) are [η] _PP and [η] _EP , respectively, the ratio ([η] _EP / [η] _PP ) is
0.5 to 2.0, and the glass transition temperature of the component (b) is −
It is characterized in that the temperature is 30 ° C or lower.

Here, a preferable range of the ratio [η] _EP / [η] _PP of the intrinsic viscosity is 0.7 to 1.7.

When any one or all of the ratio of the component (a) and the component (b), the ratio of the intrinsic viscosity, and the glass transition temperature is outside the above range, the impact resistance of the block copolymer, In particular, the surface impact resistance is not sufficient, the rigidity is lowered, and the flow characteristics are deteriorated, which is not preferable.

That is, when the content of the component (a) exceeds 95% by weight, impact resistance such as Izod impact resistance and surface impact resistance decreases, and
If it is less than wt%, the rigidity will decrease. Further, if the ratio of the intrinsic viscosity exceeds 2.0, the surface impact resistance decreases, and if it is less than 0.5, the surface impact resistance decreases and the rigidity also decreases.

Here, the component (a) means a propylene homopolymer composed of propylene units or 2 in the polymer, which can be obtained by polymerizing propylene or a propylene-containing monomer using a stereoregular catalyst or the like. It is a polymer portion derived from substantial propylene homopolymerization containing not more than wt% of ethylene units or propylene and other olefin units other than ethylene units.

On the other hand, the component (b) is an ethylene-containing ethylene unit and a propylene unit, which can be obtained by polymerizing ethylene and propylene or an appropriate amount of another olefin with a stereoregular catalyst or the like. Propylene random copolymer and ethylene homopolymer formed during copolymerization, or derived from so-called substantial ethylene-propylene random copolymerization in which the polymer contains a small amount of ethylene units and other olefin units other than propylene units. It is a random copolymer portion and may contain an ethylene homopolymer formed during copolymerization. Further, in this copolymer, the propylene homopolymer or the substantially propylene homopolymer which is separable, that is, (a)
When a component is contained, it is the remaining part excluding this.

Examples of the olefin other than propylene and ethylene include linear α-monoolefins such as 1-butene, 1-pentene, 1-hexene and 1-heptene; isobutene, 4-methyl-1-pentene, neohexene and the like. Branched α-monoolefins; butadiene, isoprene, 1,3
Examples include α-dienes such as pentadiene.

That is, the propylene block copolymer of the present invention may contain an appropriate amount of the olefin unit other than the above-mentioned propylene and ethylene in the component (a) and / or the component (b). In addition, the content of the other olefin can be selected within a range such that it is usually contained in a known polypropylene or propylene-ethylene copolymer.

The value of the intrinsic viscosity is measured in decalin at 135 ° C. Here, the concept of the intrinsic viscosity of the copolymer will be explained. This is not a value actually measured by cutting only the copolymerization portion, but a convenient concept calculated by the following calculation. First, the intrinsic viscosity [η] _PP of the crystalline polypropylene part polymerized in advance in the process of producing the block copolymer is measured. Then, the intrinsic viscosity [η] _C of the final copolymer obtained by polymerizing the block copolymerized portion is measured. At this time, when the polymerization ratio of the copolymerized portion of the block copolymer is a, the relationship of the following formula (1) is established between the intrinsic viscosity [η] _EP and [η] _C , [η] _PP of the copolymerized portion. Therefore, the intrinsic viscosity [η] _EP of the copolymerization part is calculated by the equation (2).

[Η] _C = a [η] _EP + (1-a) [η] _PP (1) [η] _EP = 1 / a [η] _C- (1 / a-1) [η] _PP (2) The propylene block copolymer of the present invention has an isotactic pentad fraction [I] of [1] ≧ −1.02 [η] _PP + 96.0 (where [η] from the viewpoint of further improving the rigidity thereof. It is more preferable that _PP has the same meaning as described above.).

Here, the isotactic pentad fraction is A. Zambelli.
In the method disclosed in Macromolecules 6 , 925 (1973), that is, the method using ¹³ C-NMR, the isotactic fraction in pentad units in the polypropylene molecular chain [component (a)]. is there. In other words, the isotactic pentad fraction is the fraction of propylene monomer units at the center of a chain in which five propylene monomer units are continuously meso-bonded. However, the attribution of peaks was carried out based on the corrected version of the above-mentioned document described in Macromolecules, 8 , 687 (1975). Specifically, ¹³
M in the total absorption peak in the methyl carbon region of the C-NMR spectrum
Isotactic pentad units are measured as the intensity fraction of mmm peaks.

The isotactic pentad fraction value in the present invention is the value of the obtained crystalline polypropylene polymer as it is, and is not the value of the polymer after extraction, fractionation and the like.

Next, an example of the method for producing the propylene block copolymer of the present invention will be described.

The propylene block copolymer of the present invention contains the component (a) and the component (b) in a predetermined ratio,
With this block copolymer, propylene, ethylene, using a stereoregular catalyst using the additive olefin as a raw material monomer, obtained by producing each block by a two-stage polymerization method, a multi-stage polymerization method, Means something.

The propylene block copolymer of the present invention is usually used as a raw material monomer such as propylene used for stereoregular polymerization, ethylene, a mixture of propylene and ethylene, or a mixture containing an appropriate amount of the above propylene and an olefin other than ethylene. It can be used to produce by stereoregular polymerization.

The two-stage polymerization method preferably used in the method of the present invention will be described below.

The stereoregular catalyst used for polymerization is a catalyst generally used for stereoregular polymerization reaction of ethylene, propylene, etc., and is usually a catalyst prepared from at least a transition metal halide and an organoaluminum compound. .
Here, as the transition metal halide, a titanium halide is preferable, and examples thereof include titanium tetrachloride and titanium trichloride. And titanium trichloride is especially suitable. Titanium trichloride is obtained by reducing titanium tetrachloride by various methods; further activated by treatment such as ball mill treatment and / or solvent washing; titanium trichloride or titanium dichloride eutectic (for example, ,
TiCl ₃ + 1 / 3AlCl ₃ ) further co-ground with amines, ethers, esters, sulfur, halogen derivatives, organic or inorganic nitrogen compounds or phosphorus compounds; trichloride liquefied in the presence of ether compounds Those obtained by precipitating from titanium: those obtained by the method described in JP-B-53-3356; and the like. Alternatively, a titanium halide supported on a magnesium compound may be used.

Examples of the organoaluminum compound include the following formula AlR _m X _3-m (wherein R represents an alkyl group, an alkoxy group or an aryl group having 1 to 10 carbon atoms, X represents a halogen atom, and n represents 0 < A compound represented by m.ltoreq.3 is preferable.

Specifically, for example, triethyl aluminum, triisobutyl aluminum, tri-n-propyl aluminum, diethyl aluminum monochloride, diethyl aluminum monobromide, diethyl aluminum monoiodide, diethyl aluminum monoethoxide, diisobutyl aluminum monoisobutoxide. ,
Examples thereof include diisobutylaluminum monohalide, diisobutylaluminum monohydride, ethylaluminum sesquichloride and ethylaluminum dichloride, and one or more of these can be used.

The stereoregular catalyst can be obtained by blending or mixing these catalyst components in a predetermined ratio. The mixing ratio or mixing ratio of each catalyst component can be set in the range of 0.1 to 1000 in terms of atomic ratio Al / M (where M is a transition metal atom such as Ti), but usually about 1 to 100. Good. Further, as the third component, for example, an electron donating compound such as alcohol, aldehyde, ether, ester, lactone, ketone, amine, amide, organophosphorus compound, organosilicon compound, thiol, thioether, thioester can be used. .

Such a stereoregular catalyst is used at each stage of the polymerization reaction in the amount and the combination of each component that are usually used.

The polymerization conditions for each stage are such that the temperature is usually 0 to 100 ° C., preferably 30.
~ 90 ℃, pressure usually 0.01 ~ 45kg / cm ² preferably 0.05 ~ 40
It should be about kg / cm ² . As the polymerization method, a known method can be applied, and examples thereof include slurry polymerization, solution polymerization, gas phase polymerization, and liquid phase polymerization using an olefin monomer as a medium.

When a solvent is used in the polymerization, as the solvent, usually, an aliphatic, alicyclic, or aromatic inert hydrocarbon can be preferably used, and specifically, for example, pentane, hexane, heptane, cyclohexane. , Benzene, toluene and the like.

The intrinsic viscosity and the ratio thereof between the component (a) and the component (b), and the glass transition temperature are controlled by the type of catalyst, the polymerization conditions such as the polymerization temperature in each stage, and the molecular weight of the hydrogen gas used during the polymerization. It can be adjusted by adjusting / selecting the amount of the agent used. On the other hand, the isotactic pentad fraction [I] can be adjusted by selecting / selecting the polymerization conditions such as the type of the polymerization catalyst and the polymerization temperature. It can be adjusted within the above range of values.

The two-step polymerization method can be carried out, for example, by the following method by selecting and adjusting the above-mentioned raw material monomer, the catalyst, the solvent, the polymerization conditions and the like.

That is, as the propylene block copolymer of the present invention, for example, in the case of producing a propylene polymer composition in which ethylene is selected as an α-olefin other than propylene by a two-stage polymerization method, in the first stage, ethylene in the polymer is The propylene homopolymer and / or propylene-ethylene copolymer having a unit content of 2% by weight or less is controlled so as to form 55 to 95% by weight of the total polymer. This can be easily achieved by adjusting the raw material composition of propylene and ethylene.

The use of a propylene-ethylene copolymer having an ethylene unit content of more than 2% by weight in the first stage is not suitable because the rigidity of the resulting composition is significantly reduced.

In the second stage, ethylene is newly fed into the reactor in which the propylene homopolymer and / or propylene-ethylene copolymer obtained in the first stage polymerization reaction is present, or ethylene and propylene are newly supplied, By setting the inside of the reactor to a predetermined polymerization condition, the second-stage polymerization reaction is caused to occur, and the propylene-ethylene copolymer is added to 5 to 5% of all the polymers.
Control to generate 45% by weight. In this way
The block copolymer in this invention can be obtained.

The propylene block copolymer thus obtained is subjected to post-treatments such as separation / recovery, washing, and drying by a known method to produce various shaped products or various molded products such as home electric appliances and automobile parts. It can be suitably used as a material for various industrial fields.

Incidentally, when producing a molded product using the powder of the propylene block copolymer obtained as described above, an appropriate amount of a heat stabilizer, an antioxidant, an ultraviolet absorber, an antiblocking agent, if necessary, Antistatic agents, neutralizing agents, lubricants, nucleating agents, colorants, pigments and other additives, inorganic fillers and the like can be added. Further, ethylene propylene rubber, polyethylene, or ethylene-propylene copolymer may be blended for the purpose of improving impact resistance.

The propylene block copolymer of the present invention thus obtained and the product thereof have excellent impact resistance, particularly excellent surface impact resistance, as well as excellent rigidity and high fluidity, and are suitable for molding. Is also an excellent polypropylene block copolymer.

〔Example〕

Examples 1 to 5 5 liters of dehydrated n-hexane were put into an autoclave with an internal volume of 10 liters equipped with a stirrer, and 1.0 g of diethylaluminum chloride and 0.3 g of titanium trichloride were added.

In the first stage polymerization reaction, liquid phase temperature was maintained at 65 ° C, hydrogen was metered so that the produced polypropylene had a predetermined intrinsic viscosity, and propylene was continuously fed so that the reaction pressure was 9 kg / cm ^2. And was stirred for 90 minutes to carry out polymerization. Then, unreacted propylene was removed and the liquidus temperature was lowered to 57 ° C. Table 1 shows [I] of the obtained polymer.

Next, in the second-stage polymerization reaction, while maintaining the temperature at 57 ° C., a propylene-ethylene mixture and measured hydrogen were supplied so as to obtain a predetermined Tg and [η] _EP / [η] _PP , Polymerization was carried out for a minute. Then, the unreacted gas was removed, 50 ml of n-butanol was added to the polymerization product, and the mixture was stirred at 65 ° C. for 1 hour for catalytic decomposition. Then, a white powdery polymer was obtained through a separation step, a washing step and a drying step. Table 1 shows the measured physical properties of the obtained polymer.

Comparative Examples 1 to 5 The same operations as those in Examples were performed except that the intrinsic viscosity of the produced polymer and the ethylene / propylene ratio at each stage were changed. The results are shown in Table 1.

[Advantages of the Invention] The propylene block copolymer of the present invention has excellent impact resistance, particularly excellent surface impact resistance, and is also excellent in rigidity, and extrusion, injection in the fields of automobiles and home appliances, injection, It is useful as a hollow molding material, and its industrial value is extremely large.

Claims (1)

[Claims] 1. A propylene block copolymer containing a crystalline polypropylene part [component (a)] and an ethylene propylene random copolymer part [(b) component], which comprises the component (a) and the component (b). When the total amount of the components is 100% by weight, the content of the component (a) is 55 to 95% by weight,
When the content of the component (b) is 5 to 45% by weight and the intrinsic viscosities of the component (a) and the component (b) are [η] _PP and [η] _EP , respectively, the ratio ([η ] _EP
/ [Η] _PP ) is 0.5 to 2.0, and the glass transition temperature of the component (b) is −30 ° C. or lower, which is a propylene block copolymer.