JPH066653B2 - Polypropylene composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polypropylene composition excellent in impact resistance, transparency, slip properties, anti-blocking properties, paintability, tear resistance, low-temperature heat-sealing properties, and the like. .

[Conventional technology]

Crystalline polypropylene is excellent in rigidity, surface gloss, heat resistance, etc., but has a drawback that it is inferior in impact resistance. As a method for improving impact resistance, a method of mixing a propylene polymer with a rubber-like substance such as polyisobutylene, polybutadiene, an amorphous ethylene / propylene copolymer, or polyethylene has been widely used. On the other hand, however, these modifiers are softer than the propylene polymer and have a drawback that the inherent characteristics of the propylene polymer, such as rigidity, heat resistance and surface hardness, are significantly lowered.

On the other hand, a film made of crystalline polypropylene is excellent in food hygiene because it has mechanical properties such as tensile strength, rigidity, surface hardness, optical properties such as gloss and transparency, and is nontoxic and odorless. Widely used in the field of. However, since polypropylene film has a high heat-sealable temperature and a narrow applicable temperature range, it was attempted to add heat-sealability by adding a low-crystalline resin such as ethylene / propylene copolymer to polypropylene. Has been. However, when these low crystalline ethylene / propylene copolymers were added, the heat-sealing property was improved, but the surface slippage became worse, and the slip property and anti-blocking property were deteriorated.

[Problems to be solved by the invention]

As a means for solving such a drawback, the present applicant has added transparency to a polypropylene, a specific ethylene / 1-butene random copolymer polymerized by a vanadium catalyst, impact resistance, low temperature embrittlement We found that it could be improved, and proposed it (Japanese Patent Publication No. 58-25693 and Japanese Patent Publication No. 58-38459).

However, from the results of subsequent studies, it was found that the above-mentioned composition has excellent physical properties, but it is somewhat inferior in slip property and anti-blocking property because it has self-adhesiveness depending on the application, and a solution in this respect has been desired.

The present invention aims to solve such problems,
The transparency of the film obtained by adding an ethylene / α-olefin random copolymer having a specific composition distribution and melting characteristics in place of the ethylene / 1-butene random copolymer polymerized by a vanadium catalyst The inventors have found that surface characteristics are improved without impairing impact resistance, low temperature heat sealability, etc., and have completed the present invention.

[Means for solving problems]

That is, the present invention, (a) propylene polymer (A) 95 to 40 parts by weight, and (b) melt flow rate (ASTM D 1238, E) is 0.01 to
50g / 10min, density 0.870 to 0.905g / cm ³ , composition distribution parameter (U) 40 or less (however Copolymer of ethylene having an average chain length ratio of methylene groups of 2.0 or less and a maximum melting point of 105 to 125 ° C. by a differential scanning calorimeter and a small proportion of α-olefin having 4 to 10 carbon atoms 5
To 60 parts by weight, a polypropylene composition excellent in impact resistance, transparency, slipping property, anti-blocking property, paintability, tear resistance, low temperature heat sealability and the like is provided. .

[Action]

The propylene polymer (A) used in the present invention is a homopolymer of propylene or propylene and other α of 50 mol% or less.
-Olefins such as ethylene, 1-butene-1 hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-tetradecene and the like, usually one or more α having 2 to 20 carbon atoms. -A block copolymer with olefin or a random copolymer with propylene and 10 mol% or less of α-olefin, which is crystalline. The propylene polymer (A) used in the present invention usually has a melt flow rate (MFR (L): ASTM D 1238, L) of 0.1 to 200 g.
/ 10 min, preferably 0.3 to 100 g / 10 min. If the MFR (L) is out of the above range, the moldability tends to be poor in any case. Incidentally, the propylene / α-olefin block copolymer is an individual polymer obtained by sequentially polymerizing olefins in the presence of a stereoregulatory catalyst in one polymerization reaction system while changing the monomer composition. It also includes a so-called polymer blend type copolymer which is not necessarily subjected to block copolymerization.

Among the propylene polymers, in order to obtain a composition having excellent transparency, it is necessary to select a propylene homopolymer or a random copolymer, while obtaining a composition having excellent impact resistance. It is preferable to select a block copolymer or a random copolymer.

Ethylene / α-olefin copolymer used in the present invention (B)
Is defined by the following (a) to (f).

(A) Melt flow rate (MFR: ASTM D 1238, E) is 0.
It is in the range of 01 to 50 g / 10 min, preferably 0.1 to 20 g / 10 min. When the MFR is out of the above range, the melt viscosity is too low or too high, and the moldability is deteriorated in any case.

(B) Density is 0.870 to 0.905 g / cm ³ , preferably 0.880
To 0.900 g / cm ³ . If the density is less than 0.870 g / cm ³ , the anti-blocking property and slip property are poor, and 0.905 g
If it exceeds / cm ³ , the effect of improving impact resistance, transparency, paintability, low temperature heat sealability, etc. is poor. The density in the present invention is a value measured by ASTM D 1505.

(C) The composition distribution is 40 or less, preferably 30 or less in the composition distribution parameter (U) represented by the following formula (1).

U = 100 × (Cw / Cn-1) (1) where Cw represents the weight average branching degree and Cn represents the number average branching degree.

When U exceeds 40, the composition distribution is wide and the improvement effect of transparency, tear resistance, impact resistance and the like is poor. Cw and Cn in the present invention are values measured by the following method. That is, in order to separate the composition of the ethylene / α-olefin copolymer (B), the copolymer (B) is dissolved in a mixed solvent of p-xylene and butyl cellosolve (volume ratio: 80/20), and then diatomaceous earth ( Product name: Celite # 560 John Manville Co. (US) coating is packed in a cylindrical column, and while the solvent having the same composition as the mixed solvent is transferred into and out of the column, the temperature inside the column is set to 30. The ethylene copolymer coated by gradually increasing the temperature from 5 ° C. to 5 ° C. to 120 ° C. was fractionated, reprecipitated in methanol, and then filtered and dried to obtain a fraction.
Then, the number of branches C per 1000 carbon atoms of each fraction is ¹³ C-NM
By the R method, the number of branches C and the cumulative weight fraction I (w) of each classification section are assumed to follow the following logarithmic normal distribution (equation (2)), and Cw and Cn are obtained by the least squares method.

I (w) = However, in the equation β ² is represented by β ² = 21n (Cw / Cn) (3), and Co ² is represented by Co ² = Cw · Cn (4).

The number of branches C by ¹³ C-NMR method is GJRay, PE Johnson
According to the method disclosed in and JRKnox, Macromolecules, 10 , 773 (1977), the signal of methylene carbon observed in the ¹³ C-NMR spectrum was used to obtain the area intensity.

(D) The average chain length ratio of the methylene groups is 2.0 or less, preferably 1.7 or less.

The average chain length ratio is a parameter indicating the random structure of ethylene and α-olefin in the molecular chain of the ethylene / α-olefin copolymer (B) used in the present invention, and the composition distribution parameter ((a)) ( U) with copolymer
This is one of the important properties that identifies the structure of (B). A copolymer having an average chain length ratio of the methylene groups exceeding 2.0 and being too large has no effect of improving antiblocking property, low temperature heat seal property, impact resistance, flex resistance, transparency and the like.

In the present invention, the average chain length ratio of methylene groups is ¹³ C-
Average chain length of methylene calculated from the degree of branching measured using NMR, and average chain length of block methylene calculated excluding the case where the number of methylene between branches (between two adjacent branches) is 6 or less. Of the block methylene average chain length / methylene average chain length.

(E) The ethylene / α-olefin copolymer (B) used in the present invention has one melting point, preferably a plurality of melting points as measured by DSC. It is in the range of 125 ° C, preferably 110 to 120 ° C. Those with a maximum melting point of less than 105 ° C have poor anti-blocking properties and slip properties.

On the other hand, if the temperature exceeds 125 ° C, the transparency, tear resistance, impact resistance, low temperature heat sealability and paintability are not improved.
The maximum melting point in the present invention is 3 mg for a sample using DSC.
After melting at 200 ℃ for 5 minutes, the temperature was decreased to 20 ℃ at a temperature decrease rate of 10 ℃ / min, and this temperature was maintained for 1 minute.
The DSC endothermic curve was measured by raising the temperature to 150 ° C. with n, and the peak or shoulder on the highest temperature side in the DSC endothermic curve was taken as the maximum melting point. When the highest melting point appears as a peak, the peak temperature is used. When the highest melting point appears as a shoulder, the temperatures at the inflection points on the high temperature side and the inflection point on the low temperature side of the shoulder are taken as the maximum melting points.

(F) A random copolymer having a substantially linear structure in which the α-olefin copolymerized with ethylene is an α-olefin having 4 to 10 carbon atoms. The α-olefin having 4 to 10 carbon atoms is, for example, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-decene or a mixture thereof. . Ethylene / α-olefin copolymer of the present invention
The content of the α-olefin component unit constituting (B) is arbitrary within a range satisfying the density and composition distribution specified by the above (B) to (D), but usually 3 to 20.
It is in the range of mol%, preferably 5 to 20 mol%.

Ethylene / α-olefin copolymer used in the present invention (B)
Has a melting point like the characteristics of (e) above,
Although it is a polymer partially having crystallinity, its crystallinity is usually in the range of 5 to 60%, preferably 10 to 50%. The crystallinity of the ethylene / α-olefin copolymer (B) is a value determined by an X-ray diffraction method. The measurement method was performed according to the method described in the following documents, using a straight line connecting the diffraction angles of 7 ° to 31.5 ° as the background. SLAggrwal and GPTilley, J.Polym.Sci., 1
8 and 17 (1955). Ethylene / α-olefin copolymer used in the present invention (B)
Can be produced, for example, by the following method. For example, a highly active solid component (a) having a specific surface area of 50 m ² / g or more containing titanium, magnesium and halogen as essential components.
With an alcohol (b) to obtain a titanium catalyst component (A), an organoaluminum compound catalyst component (B) and a halogenated hydrocarbon such as ethyl chloride or isopropyl chloride or a halogen of (B) such as silicon tetrachloride. Using a catalyst formed from the halogen compound catalyst component (C) that can be used as an agent, ethylene and α-olefin are copolymerized so as to have a predetermined density. At this time, when a part or all of the organoaluminum compound catalyst component (B) is a halogen compound, the halogen compound catalyst component
The use of (C) can be omitted. Details of these manufacturing methods are described in Japanese Patent Application No. 58-196081.

The polypropylene composition of the present invention comprises 95 to 40 parts by weight, preferably 85 to 50 parts by weight of the propylene polymer (A) and 5 to 60 parts by weight, preferably 15 to 15 parts by weight of the ethylene / α-olefin copolymer (B). Or 50 parts by weight. The amount of ethylene / α-olefin copolymer (B) is 5
If it is less than 60 parts by weight, low-temperature heat sealability, transparency, impact resistance, paintability, etc. are not improved, while if it exceeds 60 parts by weight,
The heat resistance, rigidity, slip property, anti-blocking property, etc. are reduced.

To obtain the polypropylene composition of the present invention, the propylene polymer (A) and ethylene / α-olefin copolymer
(B) and various known methods within the above range, for example, a method of mixing with a Henschel mixer, a V-blender, a ribbon blender, a tumbler blender, or the like, or after mixing, a single-screw extruder, a twin-screw extruder, a kneader, a Banbury mixer. A method of granulating or crushing after melt-kneading with the like can be adopted.

The composition of the present invention includes a weather resistance stabilizer, a heat resistance stabilizer, an antistatic agent, an antifogging agent, an antiblocking agent, a slip agent, a lubricant,
Various well-known additives which are usually used for polyolefins, such as flow-eliminating agents, pigments, dyes, flame retardants, organic or inorganic fillers, may be blended within the range not impairing the object of the present invention.

The polypropylene composition of the present invention includes a propylene polymer
In order to improve the compatibility between (A) and the ethylene / α-olefin copolymer (B), or to improve the neck-in property when the composition is used as a laminate material, a high-pressure low-density polyethylene is used. An amount of 20 parts by weight or less, more preferably 15 parts by weight or less, may be added to (A) + (B) = 100 parts by weight. Such high pressure low density polyethylene is usually MF
R is 1 to 40g / 10min, preferably 3 to 30g / 10min
In the range of 0.913 to 0.935 g / cm ³ , preferably 0.9
It is in the range of 15 to 0.930 g / cm ³ .

〔The invention's effect〕

The polypropylene composition of the present invention is excellent in impact resistance, rigidity, heat-sealing property, slip property, anti-blocking property and coating property, and a propylene homopolymer or a propylene random copolymer is used as a propylene polymer. Since the composition is also excellent in transparency, it is suitable for packaging films, sheets and blow molding materials by taking advantage of such characteristics. The composition of the present invention is also suitable for use by being laminated with nylon or polyethylene film. Further, by utilizing the above characteristics, it can be suitably used for automobile parts such as bumpers, moldings, instrument panels, console boxes, electric washing machines, vacuum cleaners, electric appliance housings such as televisions, and the like.

〔Example〕

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples as long as the gist thereof is not exceeded.

Example 1 <Catalyst preparation> In a nitrogen atmosphere, 1 mol of commercially available anhydrous magnesium chloride was suspended in dehydrated and purified hexane 2, 6 mol of ethanol was added dropwise over 1 hour with stirring, and the mixture was reacted at room temperature for 1 hour. . To this, 2.6 mol of diethylaluminum chloride was added dropwise at room temperature, and stirring was continued for 2 hours. Next, 6 mol of titanium tetrachloride was added, the system was heated to 80 ° C., and the reaction was carried out while stirring for 3 hours. The solid portion after the reaction was separated and washed repeatedly with purified hexane. The solid (A-1)
The composition was as follows.

Next, convert to Ti of A-1 suspended in purified hexane.
To 50 mmol, 500 mmol of ethanol was added at room temperature, the temperature was raised to 80 ° C., and the reaction was carried out for 1 hour. After the reaction, the temperature was lowered to room temperature, 150 mmol of triethylaluminum was added, and the reaction was carried out with stirring for 1 hour. The solid portion after the reaction was repeatedly washed with purified hexane. The composition of the catalyst (B-1) thus obtained was as follows.

<Polymerization> Using a continuous polymerization reactor with an internal volume of 200, dehydrated and purified hexane was 100 / hr, ethylaluminum sesquichloride 15 mmol / hr, and the catalyst (B-1) obtained above was used.
It was continuously supplied at a rate of 1.0 mmol / hr in terms of Ti, and simultaneously 10 kg / hr of ethylene and 1-
Butene 33 kg / hr, hydrogen was continuously supplied at a rate of 20 / hr, polymerization temperature 150 ° C., total pressure 30 kg / cm ² , residence time 1 hour,
The copolymerization was carried out under the condition that the concentration of the copolymer in the solvent hexane was 100 g /. The catalytic activity corresponded to 13000 g-copolymer / mmol-Ti.

The physical properties of the obtained ethylene / 1-butene copolymer (EBC-1) are MFR: 2.2 g / 10 min, density 0.889 g / cm ³ , U: 23, average chain length ratio of methylene groups: 1.26, maximum melting point: 118.2 ° C
(Other peaks at 72.0 ℃ and 103.5 ℃), Crystallinity: 18.
4% and 1-butene content: 9.7 mol%.

<Film molding> EBC-1: 15 parts by weight and MFE (L): 6.2 g / 10 mi
n, ethylene content: 3.5 mol% propylene / ethylene random copolymer (PP-1): 85 parts by weight were mixed with a Henschel mixer, and then the mixed composition was 250 mm wide and thick with a T-die film molding machine. A 50 μm thick film was formed. The resin temperature after molding was 210 ° C., the extruder was 40 mmφ, the screw rotation speed was 80 rpm, the die width was 300 mm, and the chill roll temperature was 20 ° C.

The physical properties of this film were measured by the following methods.

Haze (%): ASTM D 1003 Tear strength (Elmendorf: kg / cm): JIS Z 1702 Impact strength (kgcm / cm): ASTM D 3420 Blocking degree: Cut 20 cm x 25 cm test piece from the film, 2 Overlay the films and put them under 40 kg under a load of 10 kg.
After leaving it at 24 ° C. for 24 hours, it was performed according to the method of ASTM D-1893 using an autograph manufactured by Shimadzu Corporation.

Friction coefficient: ASTM D 1894 Example 2 Instead of EBC-1 used in Example 1, MFR: 4.5 g / 10 min,
Density: 0.893 g / cm ³ , U: 25, average chain length ratio of methylene groups
1.40, Maximum melting point: 122.5 ℃ (other peaks at 111.5 ℃ and 86.5 ℃) Crystallinity 41.5% and 4-methylene-1-pentene content 6.5mol% ethylene-4-methyl-1-pentene copolymer The same procedure as in Example 1 was performed except that (EMC-1) was used. The results are shown in Table 1.

Comparative Example 1 MFR obtained by using a vanadium-based catalyst instead of EBC-1 used in Example 1: 3.9 g / 10 min, density: 0.886 g / cm ³ ,
Example 1 except that an ethylene / 1-butene random copolymer (EBC-2) having a maximum melting point of 68 ° C. (single peak), a crystallinity of 8.3% and a 1-butene content of 10.5 mol% was used. I went the same way. The results are shown in Table 1.

Example 3 EBC-1 used in Example 1: 15 parts by weight and MFR (L): 25 g
/ 10 min, after mixing 80 parts by weight of propylene / ethylene block copolymer (PP-2) with an ethylene content of 12 mol% with a Henschel mixer, melt kneading with a uniaxial extruder (set temperature 210 ° C.), Composition II was obtained. The composition II was then used to form test specimens using an injection molding machine. The physical properties of the sample were evaluated by the following methods.

Bending properties Flexural initial modulus (kg / cm ² ), yield stress (kg / cm ² ): AS
TM D 790 Izod impact strength (with notch) kg ・ cm / cm ： ASTM D 256 Paint adhesion strength: Wash the sample with 1,1,1-trichloroethane vapor and use a primer (trade name PP coating primer P-401,
After coating (10μ) with Mitsui Petrochemical Industry Co., Ltd., it is dried. After that, urethane coating (40μ) was performed and dried at 100 ° C for 30 minutes. After leaving it at room temperature for 5 minutes, cut it out to a width of 10 mm and remove the tip.
The 180 ° C peel strength (tensile speed 30 mm / min) was measured.

Comparative Example 2 Example 3 was repeated except that EBC-2 was used instead of EBC-1 used in Example 3. The results are shown in Table 2.

Claims (1)

[Claims] 1. A propylene polymer (A) 95 to 40 parts by weight, and (b) a melt flow rate (ASTM D 1238, E) of 0.01 to 0.01.
50g / 10min, density 0.870 to 0.905g / cm ³ , composition distribution parameter (U) 40 or less (however A copolymer of ethylene having an average chain length ratio of methylene groups of 2.0 or less, a maximum melting point of 105 to 125 ° C. by differential scanning calorimeter (DSC), and a small proportion of an α-olefin having 4 to 10 carbon atoms 5 to 60 And a polypropylene composition.