JPH07252389A - Thermally stable polypropylene composition - Google Patents

Abstract

PURPOSE:To obtain a compsn. which gives a molded article excellent in resistance to thermal discoloration and does not allow degradation products to deposit during molding by compounding polypropylene with a specifically treated talc. CONSTITUTION:This compsn. is prepd. by compounding polypropylene with talc treated with a stearic acid deriv. and melamine. A pref. talc is the one heat-treated at 20-170 deg.C. The stearic acid deriv. and melamine are each used pref. in an amt. of 0.005-10wt.% of talc. Pref. at least one stearic acid deriv. is used which is selected from the group consisting of stearic acid, ethylenebisstearamide, and glycerol monostearate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-stable polypropylene composition used as a molded product for automobile parts and as a material for microwave oven cooking tableware.

[0002]

2. Description of the Prior Art The heat distortion temperature of polypropylene for molded products such as sheets is about 75 ° C. to 105 ° C. For example, a molded product molded using a polypropylene composition containing 30% by weight of talc as a filler. Has a heat distortion temperature of 1
It can be used up to 30 ℃, and it can be used as tableware for automobile parts and microwave oven cooking.

Talc is obtained by crushing and classifying natural talc, and the main component is generally magnesium silicate containing impurities such as salts of calcium, iron, sodium and potassium. Depending on the place of origin, nickel and manganese may be included. Of these impurities, iron, nickel, and manganese have a accelerating effect on the deterioration of polypropylene, and have a drawback that various adverse effects are exerted in the molding process depending on the content.

For example, when a sheet or the like is extrusion-molded, a composition of deteriorated polypropylene and talc, which is commonly referred to as a "eye crocodile", deposits on the lip of an extruder and adheres to the sheet formed as it grows. A series of defective products that significantly impair the appearance of In order to prevent this, physical removal of "eye stains" occurs every time, a large amount of hindered phenol, phosphorus-based antioxidant is added,
Although measures such as using a heavy metal deactivator in combination and lowering the molding temperature to slow down the molding speed have been taken, there still remains a problem that a sufficient effect is not obtained.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above problems, and provides a polypropylene composition having excellent thermochromic properties of a molded product and not causing deposition of a deterioration product during molding. The task is to do.

[0006]

In order to achieve the above-mentioned object, the heat-stable polypropylene composition of the present invention comprises polypropylene, a talc as a filler, and a treated talc treated with a stearic acid derivative and melamine. It is characterized by The talc is preferably talc heat-treated at 20 ° C to 170 ° C (claim 2). Talc is 110
It is more preferable that the talc is heat-treated at a temperature of 150 to 150 ° C (claim 3). The stearic acid derivative is preferably composed of at least one selected from stearic acid, ethylenebisstearic acid amide, and glycerin monostearate (claim 4) (claim 6).
The addition amount of the stearic acid derivative and melamine added to talc is 0.005 to 10% by weight based on talc, respectively.
Is preferred (Claim 5).

As the polypropylene, a homopolymer, a random or block copolymer containing 15% or less of ethylene and / or butene-1 and a terpolymer can be used. In addition to polypropylene, high density or low density polyethylene or acrylonitrile / butadiene / styrene polymer can be used. It can be used less than 50%.

Talc is produced in China, North Korea, India,
Although it can be produced from Australia or the like, the average particle size is preferably 3 μ to 20 μ, and the addition amount is appropriately 5% to 50%.

Examples of stearic acid derivatives include stearic acid, stearyl stearate, trimethylolpropane stearate, glycerine stearate, polyglycerin stearate, pentaerythritol stearate, sorbitan stearate, sucrose stearate. Acid esters, acidic-, neutral-, basic-stearic acid metal salts, and metals such as aluminum, calcium, magnesium and zinc. Hydrogenated soybean oil, methylenebisstearic acid amide, ethylenebisstearic acid amide, stearic acid amide,
Is mentioned.

Further, hydroxystearic acid and esters of hydroxystearic acid such as propylene glycol, trimethylolpropane, mono- and polyglycerin, pentaerythritol, sorbitan and sucrose, acidic, neutral and basic aluminum of hydroxystearic acid, Metal soap such as calcium, magnesium and zinc,
Hydrogenated castor oil, ethylene bishydroxystearic acid amide, and hydroxystearic acid amide are mentioned.

The amount of the above stearic acid derivative added is 0.005 to 10% by weight, more preferably 0.1 to 0.3% by weight, based on talc.

Melamine has a purity of 99.9% or more, an average particle size of 10 to 30 μ, and an addition amount of 0.005 to 5% by weight, more preferably 0.1 to 0.3% by weight. The heat treatment of talc is 20 ° C. to 170 ° C., more preferably the heat treatment at 110 ° C. to 150 ° C. at which water present in talc as a filler can be evaporated. The atmosphere for heat treatment may be vacuum, or the atmosphere may be replaced with nitrogen gas which is an inert gas.

A usual high-speed stirrer (for example, Henschel, super mixer) or the like is used for the stirring process of adding and mixing talc with a stearic acid derivative and melamine, but a low-speed stirrer (for example, ribbon blender) equipped with a heating device is used Various agitators can also be used.

In addition to the above additives, commonly used antioxidants such as phenol-based, sulfur-containing and phosphorus-containing antioxidants, salicylates, benzophenones, cyanoacrylates, benzotriazoles and hindered amines UV stabilizers such as, pigments, antistatic agents, lubricants, fillers, flame retardants, and heavy metal deactivators can also be used.

[0015]

In the heat-stable polypropylene composition of the present invention, since talc is heat-treated as a filler for polypropylene, stearic acid derivative and melamine are added and mixed, and the mixture is stirred, the talc is added to the polypropylene. By improving the dispersibility of the composition and significantly improving the thermochromic property and processability, there is no phenomenon in which the composition of deteriorated polypropylene and talc, which is commonly referred to as "eye resin," during extrusion molding is deposited on the lip of the die. In addition, it is possible to prevent the occurrence of defective products in which the "eye stain" which is the deposit adheres to the sheet and remarkably deteriorates the appearance.

[0016]

EXAMPLES The heat-stable polypropylene composition of the present invention will be described below with reference to examples, but the present invention is not limited to the following examples. In the text, “part” means part by weight.

Examples 1-8 (Table 1) and Comparative Examples 1-6
(Table 2) 70 parts of a propylene resin (melt flow rate 0.5) was pretreated with 0.5 part of an additive containing a phenol-based antioxidant, a phosphorus-based antioxidant and a metal soap, and talc at a temperature shown in Table 1. After that, 0.1 part of melamine and the treating agent shown in Table 1 were added and mixed with a treated talc mixed for 2 minutes with a stirrer, and the mixture was stirred and mixed, and a mill test was performed with a test roll at 200 ° C. The dispersibility of talc was evaluated by measuring the time (seconds) at which the talc attached to the roll on the opposite side disappeared. The shorter the disappearance time of talc, the better the dispersibility. Then
The sheet taken out was subjected to a thermal stability test in an oven at 250 ° C., and a 10-level evaluation was performed, in which no discoloration by visual observation was 1, and dark brown was 10. The above test results are shown in Table 1. As is clear from these results, heat-treated talc with melamine and stearic acid added and dispersed has good dispersibility in polypropylene,
Moreover, there was little thermal discoloration and the thermal stability was good.

Examples 9 to 17 (Table 3) To 70 parts of a propylene resin (melt flow rate 0.5), 0.5 part of an additive containing a phenol-based, phosphorus-based antioxidant and metal soap, and 130 ° C. To 30 parts of talc that had been heat-treated for 30 minutes, 0.1 part of melamine and each part of the treatment agent shown in Table 3 were added and mixed with a stirrer for 2 minutes. The test conditions were the same as in Examples 1 to 8 above. As is clear from the results shown in Table 3, the dispersibility and the thermochromic property are improved as the compounding amount is increased.

Examples 18 to 20 and Comparative Example 7 (Table 4) 0.5 part of an additive containing 70 parts of a polypropylene block copolymer (melt flow rate: 0.5), a phenol type antioxidant, a phosphorus type antioxidant and a metal soap. Was added in advance with a high-speed stirrer at a maximum temperature of 140 ° C. and treated talc obtained by mixing and stirring the compounding agents shown in Table 4 to prepare a compounding mixture having a width of 52 mm with a 65 mm vented bi-directional extruder
A sheet was formed under the conditions of Table 4 by a coat hanger die having 0 mm and a lip clearance of 0.5 mm. Comparative Example 7
Is a polypropylene block copolymer, the above additives, melamine and talc were added and mixed and stirred under the same conditions with a high speed stirrer. As is clear from Table 4, the polypropylene composition of this example shows that it does not cause "eyes" and is excellent in processability and discoloration as compared with the composition prepared by the conventional method. There is.

[0020]

The heat-stable polypropylene composition of the present invention uses, as a filler for polypropylene, a talc filler obtained by heat-treating talc, then adding and mixing a stearic acid derivative and melamine and stirring the mixture. When performing extrusion molding, the composition of deteriorated polypropylene and talc, which is commonly referred to as "eye crocodile", does not deposit on the lip of the extruder, and the deposit adheres to the sheet and significantly deteriorates the appearance of the sheet. Occurrence can be prevented. Further, there are great advantages such as the discolorability due to heat is improved, the thermal stability is improved, and the workability in the manufacturing process of the molded product is excellent.

[Table 1]

[Table 2]

[Table 3]

[Table 4]

Claims (6)

[Claims] 1. A heat-stable polypropylene composition comprising polypropylene, and as a filler, treated talc obtained by treating talc with a stearic acid derivative and melamine. 2. The heat stable polypropylene composition according to claim 1, wherein the talc is talc heat-treated at 20 ° C. to 170 ° C. 3. The heat stable polypropylene composition according to claim 1, wherein the talc is talc heat-treated at 110 ° C. to 150 ° C. 4. The stearic acid derivative is stearic acid,
The heat-stable polypropylene composition according to claim 2, comprising at least one selected from ethylene bis-stearic acid amide and glycerin monostearate. 5. The amount of the stearic acid derivative and melamine added to talc is 0.00 relative to talc, respectively.
The heat stable polypropylene composition according to claim 2 or 3, which is 5 to 10% by weight. 6. The stearic acid derivative is stearic acid,
The heat-stable polypropylene composition according to claim 5, comprising at least one selected from ethylene bis-stearic acid amide and glycerin monostearate.