JPS6119646A - Polypropylene composition - Google Patents

Abstract

PURPOSE:A polypropylene composition which gives a molded article having excellent transparency, anti-fogging properties, and softness, and is made by the degradation of a crystalline propylene-ethylene random copolymer, followed by the incorporation of a specified additive therein. CONSTITUTION:About 0.001-0.5pt.wt. radical generator is incorporated into 100pts.wt. crystalline propylene-ethylene random copolymer (having an ethylene content of 4.5-6wt% and a melt flow rate of 0.1-3g/10min), and this mixture is kneaded at about 180-300 deg.C to undergo degradation, giving a melt flow rate of 10-100g/10min. 0.05-0.5pt.wt. compound of the formula (where R is a 1-5C alkyl, an alkoxy, a halogen or hydroxyl; m and n each are 0-3) [e.g. dibenzylidenesorbitol or 1,3,2,4-di(p-methylbenzylidene)sorbitol] as an additive is incorporated into 100pts.wt. obtained copolymer as mentioned above.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a polypropylene composition suitable for various molded articles having excellent transparency, antifogging properties, and flexibility.

(Prior art) In recent years, there has been a demand for materials that have both transparency and flexibility for various containers for industrial, household, and medical use. Polyvinyl chloride is a material that meets this demand, but it is especially There are safety issues for medical and medical purposes.

Therefore, polyolefin materials have been attracting attention from the viewpoint of safety, and recently propylene-based materials have been used from the viewpoint of high transparency and softness.
Ethylene random copolymers have received particular attention.

However, when the ethylene content is increased for softening, the amount of solvent-soluble by-products increases rapidly, resulting in a significant decrease in productivity. On the other hand, in order to eliminate this drawback, there is a method of increasing the molecular weight during polymerization and lowering the product molecular weight by adding a radical generator during granulation. There is a new drawback: inferiority.

In terms of additive formulation, it is known that transparency can be improved by incorporating dibenzylidene sorbitol, but the effect was insufficient.

(Problems to be solved by the invention) In view of this situation, the inventors of the present invention have conducted intensive research and have found that
By degrading a propylene-ethylene random copolymer with a specific ethylene content to an appropriate stage in the presence of a radical generator and further adding specific additives, the generation of solvent-soluble by-products is suppressed. At the same time, they succeeded in obtaining a polypropylene composition that has excellent transparency, antifogging properties, and flexibility, and have accomplished the present invention.

(Means for solving the problems) That is, the present invention provides [ethylene content of 4.5 to 6% by weight]
, melt flow rate) (MFR) o, 1~3f/10
of crystalline propylene-ethylene random copolymer,
Degraded in the presence of a radical generator, resulting in an MFR of 10 to 1
005'/10 minutes and the general formula (R is an alkyl group having 1 to 5 carbon atoms, an alkoxy group, a halogen atom or a hydroxyl group; m and n are integers of θ to 3; R is A polypropylene composition characterized by comprising 0.05 to 0.5 parts by weight of a compound represented by (the same compound may be used as an ingredient, and m and n may be the same in the same compound).
It is.

(Function) The propylene-ethylene random copolymer used in the present invention has an ethylene content of 4.5 to 6% by weight, preferably 5.0% by weight.
~5.8% by weight. If the ethylene content is less than 4.5% by weight, the flexibility and transparency will be insufficient, while if the ethylene content exceeds 6% by weight, the amount of solvent-soluble polymer will increase and productivity will drop significantly. Furthermore, the MFR before degradation is o, i~3r/l.

minutes (preferably 0.5 to 2.55'/10 minutes).

If the MFR before degradation is less than 0.1 f/10 minutes, the antifogging property after molding will deteriorate, while if the MFR is more than 710 minutes, the amount of solvent-soluble by-products will increase, significantly reducing productivity.

Such an ethylene-propylene random copolymer is generally produced by directly applying the production technology of ethylene-propylene random copolymerization using a Ziegler type stereospecific polymerization catalyst in the presence or absence of an inert solvent. .

As the Ziegler type stereospecific polymerization catalyst, a catalyst system containing various titanium trichloride or magnesium chloride-supported titanium-containing catalysts and an organoaluminum compound such as diethylaluminum chloride or triethylaluminum chloride as the main components can be suitably used. Molecular weight is controlled by hydrogen.

Preferred radical generators used in the present invention include, for example, hydroperoxides, alkyl peroxides, acyl peroxides, ketone peroxides, alkyl peresters, peroxydicarbonates, and silicones. Organic peroxides such as peroxides and azo compounds are suitable, and specifically, t-
Butyl hydroperoxide, dicumyl peroxide, 1゜3-bis(t-butylperoxyisopropyl)benzene, benzoyl peroxide, methyl isobutyl ketone peroxide, t-butyl perbenzoate, diisopropyl peroxydicarbonate, vinyl tris( Examples thereof include t-butylperoxy)silane, azobisisobutyronitrile, and 2,2'-azobis(2,4-dimethylvaleronitrile). The amount of these radical generators used is generally in the range of 0.001 to 0.5 parts by weight based on 100 parts by weight of the copolymer.

The degradation is carried out by adding a radical generator to the copolymer and kneading it at 180 to 300°C in a mixer such as an extruder. When mixing wires for deterioration, antioxidants, lubricants, mold corrosion inhibitors, ultraviolet absorbers, etc. may be added at the same time.

If the MFR of the degraded propylene-ethylene random copolymer thus obtained is less than 10 t/10 min, injection moldability will be insufficient, while if it exceeds 100 f/10 min, transparency will deteriorate and softness will occur. is inferior.

Further, dibenzylidenefulbitol or bis(substituted benzylidene)sorbitol used in the present invention has the general formula % (R is an alkyl group having 1 to 5 carbon atoms, an alkoxy group, a halogen atom, or a hydroxyl group; m and n are θ to An integer of 3: R may be in the same compound, and m and n may be the same in the same compound. Specifically, for example, dibenzylidenefulbitol, 1,3,2.
4-di(p-methylbenzylidene)sorbitol, 1.
3,2,4-di(p-chlorobensyritene)sorbitol, 1,3,2,4-di(p-methoxybenzylidene)
Examples include sorbitol.

This compound is blended in an amount of 0.05 to 0.5 parts by weight, preferably 0.1 to 0.3 parts by weight, per 100 parts by weight of the propylene-ethylene random copolymer.

If it is less than 0.05 parts by weight, there is hardly any improvement in transparency or anti-fogging properties, and if it exceeds 0.5 parts by weight, not only will there be problems with bleeding, but the economy is also unfavorable. The addition of this
It is most rational to use the degradation process using the radical generator described above.

In addition, various additives can be appropriately blended into the composition of the present invention within a range that does not impair the effects of the invention. Specifically, antioxidants, light stabilizers, ultraviolet absorbers, nucleating agents,
Examples include antistatic agents, pigments, pigment dispersants, lubricants, neutralizing agents, acid scavengers, and the like.

In particular, it is preferable to add antioxidants in order to maintain stability in granulation and molding processes, and neutralizing or hydrochloric acid scavengers such as metal soaps and hydrotalcites exhibit the effects of this patent. The above is more preferable.

(Examples) Example 1 After the interior of a stainless steel reactor with an internal volume of 200 tons equipped with a stirring blade was sufficiently replaced with propylene gas, heptane Sat was introduced as a polymerization solvent. Keep the internal temperature at 50℃,
Diethylaluminum chloride (DBAC) as a catalyst
)50? and titanium trichloride (TMB-07 manufactured by Marubeni Tsurubei Chemical Co., Ltd.) i.

Added 9. Subsequently, propylene was fed at a rate of 53 Kf/hr for 15 minutes. During this time, hydrogen was supplied so that the gas phase concentration was 3% by volume. Next, set the temperature inside the vessel to 55℃.
At the same time, the hydrogen concentration was set to 6.2% by volume, propylene was continued to be supplied at a rate of 5.83 Kg/hr, and ethylene was newly supplied at a rate of 0.37 Kg/hr, so that propylene and ethylene were each It was fed for 360 minutes. The total amount of propylene and ethylene supplied during this period was 3 seconds and 2.27 kg of oP4 oil. At this point, the internal pressure is 2.64! q/ca G, but the supply of propylene and hydrogen was stopped, and while only ethylene was supplied at a rate of 0, zao Kp/hour, the pressure inside the vessel was increased to 2. The reaction was completed by lowering the concentration to OK9/crIG. Subsequently, 1.8 g of butanol was added into the reactor, and the catalyst was decomposed at 65° C. for 3 hours, and then the catalyst was removed by washing with water. Further, a product copolymer 31.8KIi was obtained through centrifugation and drying steps. The amount of by-product amorphous copolymer solubilized in the polymerization solvent was 2.21 kg.

The ethylene content in the obtained propylene-ethylene random copolymer was 5.6% by weight, and the 1 MFR was 1.2 f/10 min.

To 100 parts by weight of this propylene-ethylene random copolymer, tetrakis[methylene (3°5-di-t-butyl-4-hydroxyhydrocinnamate)]butane (
antioxidant) 0.1 part by weight, calcium stearate (
Neutralizing agent) 0.1 parts by weight, 0.2 parts by weight of 1.3,2,4-di(paramethylbenzylidene) sorbitol, and 2.
0.055 parts by weight of 5-dimethyl-2,5-di(t-butylperoxy)hexane (peroxide) was added and mixed, followed by granulation at 250°C.

This random copolymer composition pellet was applied to an injection molding machine with a screw diameter of 40 m (cylinder temperature set at 240° C.) to prepare a sample. The Olzen flexural modulus (based on ASTM-D 747) was measured for this sample.

Haze (according to JIS-6714) and DuPont impact strength were measured on a 100X100XI gourd thickness specimen. The degree of cloudiness is determined by using a test piece for haze measurement.
The haze after being kept in an oven at 0° C. for 48 hours was measured and evaluated based on the difference from the haze before the open treatment. Generally, the haze difference needs to be within 6%. MFH was measured in accordance with JIs-7210. The results are shown in Table 1.

Example 2 A random copolymer was produced in the same manner as in Example 1, except that the hydrogen concentration in the gas phase was adjusted to 1.6% by volume after the temperature in the polymerization vessel reached 55°C.

The random copolymer still obtained was treated with radical generator 2,
Each sheet was formed in the same manner as in Example 1, except that 0.075 parts by weight of 5-dimethyl-2,5-di(t-butylperoxy)hexane (peroxide) was added, and the physical properties were evaluated. . The results are shown in Table 1.

Example 3 A random copolymer was produced in the same manner as in Example 1, except that the hydrogen concentration in the gas phase was adjusted to 10% by volume after the temperature in the polymerization vessel reached 55°C.

The obtained random copolymer also contains radical generator 2,
Each sheet was formed in the same manner as in Example 1 except that 0.040 parts by weight of 5-dimethyl-2,5-di(t-butylperoxy)hexane (peroxide) was added, and the physical properties were evaluated. . The results are shown in Table 1.

Comparative Example 1 Using the same random copolymer as in Example 1, 1.3
, 2.4-di(paramethylbenzylidene)ne Rubitol was formed into a sheet under the same conditions as in Example 1 except that rubitol was not added, and the physical properties thereof were evaluated. The results are shown in Table 1.

Comparative Example 2 A random copolymer was produced in the same manner as in Example 1, except that the hydrogen concentration in the gas phase was set to 0.4% by volume after the temperature in the polymerization vessel reached 55°C.

In addition, the obtained random copolymer has a radical generator 2
,5-dimethyl-2,5-di(t-butylperoxy)
Each sheet was formed in the same manner as in Example 1 except that 0.100 parts by weight of hexane (peroxide) was added, and the physical properties were evaluated. The results are shown in Table 1.

Comparative Example 3 Same polymer structure as used in Example 1 (propylene-
A random copolymer having a random copolymer composition (ethylene random copolymer composition) whose MFR alone is equal to the value after treatment with the radical generator 2.5-dimethyl-2゜5-di(t-butylperoxy)hexane was copolymerized. A random copolymer was produced under the same conditions as in Example 1, except that the hydrogen concentration was set at 28% by volume when the temperature in the polymerization vessel reached 60°C. The obtained copolymers were formed into sheets in the same manner as in Example 1 except that 2,5-dimethyl-2,5-di(t-butylperoxy)hexane was not added, and the physical properties were evaluated. . The results are shown in Table 1.

Comparative Example 4 After the temperature inside the polymerization vessel reached 55°C, the hydrogen concentration in the gas phase was set to 4.7% by volume, and the ethylene supply rate was set to 0.260%.
Kf/hour (therefore, the total ethylene supply amount during this period was 1.56 Kg), and the ethylene supply rate, supply time, and total supply amount after stopping the propylene supply were each 0.16 Kg. o6/hour, 33 minutes and 0
．． A random copolymer was produced in the same manner as in Example 1 except that 088 Kf was used. The results are shown in Table 1.

Comparative Example 5 After the temperature inside the polymerization vessel reached 55°C, the hydrogen concentration in the gas phase was set to 8.2% by volume, and the ethylene supply rate was set to 0.455%.
Kq/hour (therefore, the total amount of ethylene supplied during this period was set to 2.731'g), and the feed rate, time, and total amount of ethylene after stopping the propylene supply were changed to 0. A random copolymer was produced in the same manner as in Example 1, except that the reaction time was 0.270 Kg/hour for 16 minutes and the ratio was 0.072 to 9. The results are shown in Table 1.

(The following is a blank space) (Effects of the Invention) The present invention provides a composition that suppresses the generation of solvent-soluble by-product polymers and has excellent transparency, antifogging properties, and flexibility in the above-mentioned process and polymerization. , the degree of effect is remarkable.

Claims (1)

[Claims] Ethylene content: 4.5 to 6% by weight, melt flow rate: 0
．． A crystalline propylene-ethylene random copolymer of 1 to 3 g/10 min is degraded in the presence of a radical generator,
100 parts by weight of the copolymer with a melt flow rate of 10 to 100 g/10 minutes, and the general formula ▲ Numerical formula, chemical formula, table, etc. ▼ (R is an alkyl group having 1 to 5 carbon atoms, an alkoxy group, a halogen atom, or From 0.05 to 0.5 parts by weight of a compound represented by a hydroxyl group; m and n are integers of 0 to 3; R may be different in the same compound, and m and n may be the same in the same compound. A polypropylene composition characterized by: