JPH11292931A - Production of propylenic polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a degraded propylenic polymer by heating a propylenic polymer and a specific peroxide, capable of obtaining the degraded polymer, having improved polymer flowability and having a reduced smell. SOLUTION: This method for producing a degraded propylenic polymer comprises heating a propylenic polymer (for example, isotactic propylene polymer or crystalline propylene-ethylene random copolymer) and a peroxide. Therein, di-t-hexylperoxide is used as the peroxide. The di-t-hexylperoxide is preferably used in an amount of 0.005-0.1 pt.wt. per 100 pts.wt. of the propylenic polymer. The objective polymer is preferably produced by a method using a master batch preliminarily prepared by mixing the propylenic polymer with the di-t-hexylperoxide in a high concentration. The propylenic polymer is generally mixed with the master batch, fed into an extruder, heated and kneaded. The temperature of the thermal treatment is preferably 170-270 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a degraded propylene-based polymer having a low odor while improving the flowability of the polymer.

[0002]

2. Description of the Related Art Propylene polymer is a material having excellent mechanical properties, but usually has a relatively high molecular weight at the time of its production, and therefore, when it is used as it is, it has poor fluidity and is difficult to work. Therefore, generally, a method of improving the fluidity by degrading the propylene-based polymer and appropriately reducing the molecular weight has been performed. As a degradation method, a method of heating using a kneader or the like together with a compound that generates radicals is generally used. At that time, a relatively high-temperature decomposition peroxide is used as a compound that generates a radical. For example, Japanese Patent Publication No. 44-151
No. 86 discloses a method using dicumyl peroxide. JP-A-48-79851 discloses 2,5-bis (t-butylperoxy) 2,5-dimethylhexane and 2,5-bis (t-butylperoxy).
A method using 2,5-dimethylhexine-3 is disclosed.

[0003]

Although each of the above methods is a useful method, there is a problem of odor due to a thermal decomposition product of peroxide. A peroxide having a cumyl group, such as dicumyl peroxide, produces acetophenone. 2,5-bis (t-butylperoxy) 2,5-dimethylhexane produces a furan compound and 2,5-bis (t-butylperoxy) 2,5-dimethylhexyne-3 produces an acetylene derivative Then, a odor peculiar to each is generated, which causes a problem that the working environment is deteriorated and the odor remains in the product. Therefore, there has been a demand for a peroxide having a low odor and a high efficiency of degeneration. An object of the present invention is to provide a method for producing a degraded propylene-based polymer having a low odor while improving the flowability of the polymer.

[0004]

The present inventors have studied over a long period of time a method for solving the above-mentioned problems of the conventional method, and as a result, it has been found that polypropylene degraded by heating a propylene-based polymer and a specific peroxide. The present invention was found by finding a method for producing a polymer. That is, the present invention provides a method for producing a degraded propylene-based polymer by heating a propylene-based polymer and a peroxide, wherein the di-t-hexyl peroxide is used as the peroxide. It is a manufacturing method.

[0005]

Embodiments of the present invention will be described below in more detail. The propylene-based polymer used in the present invention is a crystalline polypropylene,
Mainly propylene-only polymer and propylene,
It refers to a copolymer with another α-olefin. Specifically, for example, isotactic propylene, crystalline propylene
Examples include an ethylene random copolymer, a crystalline propylene-ethylene block copolymer, and a crystalline propylene-butene-1 random copolymer.

[0006] Di-t-hexyl peroxide used in the present invention is di (1,1-dimethylbutyl) peroxide or di (1,1,2-trimethylpropyl).
Peroxides, which are collectively referred to. These are usually used alone, but may be used as a mixture. These peroxides are used to convert the corresponding t-alcohol to -20 ° C in the presence of sulfuric acid and hydrogen peroxide.
It is obtained by reacting at 30 ° C. for 1 to 5 hours.

In the present invention, di-t-hexyl peroxide is used in an amount of usually 0.001 to 0.5 part by weight, preferably 0.1 to 0.5 part by weight, based on 100 parts by weight of the propylene polymer.
005 to 0.1 parts by weight are used. If the amount is less than 0.001 part by weight, the effect of degradation is not sufficient. If the amount is more than 0.5 part by weight, the molecular weight of the propylene-based polymer becomes too small and the mechanical properties tend to decrease.

In the present invention, an antioxidant, an ultraviolet absorber, and the like which are usually added to a propylene polymer are used.
Clarifying agent, nucleating agent, lubricant, antistatic agent, antiblocking agent, pigment, heavy metal deactivator, metal soap, antibacterial agent,
An inorganic filler or the like can be contained. As for the antioxidant, for example, 2,6-di-t-butyl-p-cresol, tetrakis (methylene-3- (3 ′, 5′-di-
hindered phenols such as t-butyl-4'-hydroxyphenyl) propionate) methane;
Phosphorus compounds such as 4-di-t-butylphenyl) phosphite and sulfur compounds such as dilauryldithiopropionate can be used. For the ultraviolet absorber, for example, 2-
Hydroxy-4-octoxybenzophenone, 2-
(2'-hydroxy-3'-t-butyl-5'-methylphenyl) -5-chlorobenzotriazole and the like.

There are mainly two methods for producing the degraded propylene-based polymer of the present invention. One is a method of preparing a master batch in which the peroxide is mixed in advance with a propylene-based polymer, silica, clay, calcium stearate, zeolite, or the like so that the peroxide is contained at a high concentration. Generally, this masterbatch is added to a propylene-based polymer, supplied to an extruder, and heated and kneaded to produce a degraded propylene-based polymer.However, the propylene-based polymer is supplied to an extruder and heated. After kneading, a master batch may be added and reacted. Another method is to directly use a small amount of the peroxide in an amount suitable for degrading the propylene-based polymer without preparing a masterbatch. That is, generally, a peroxide in an amount suitable for degradation is added to a propylene-based polymer, supplied to an extruder, and heated and kneaded to produce a degraded propylene-based polymer. After supplying the polymer to the extruder and kneading the mixture by heating, an appropriate amount of peroxide for degradation may be added and reacted. The former method using a masterbatch is a preferable production method because the dispersion of the peroxide in the propylene-based polymer can be made more uniform.

As the kneading machine, all the usual kneading machines can be used, but in particular, a Henschel mixer, a ribbon blender, a paddle mixer, a mix master, a pony mixer, a Nauta mixer, an omni mixer, a V-type mixer,
A kneading machine such as a Banbury mixer, a kneader, and a screw mixer is preferable. As the extruder, any ordinary extruder can be used, but a single-screw extruder, a twin-screw extruder, a Brabender and the like are particularly preferable.

The heat treatment temperature in the reaction of the present invention is generally from 150 to 300 ° C, preferably from 170 to 270 ° C. If the heat treatment temperature is lower than 150 ° C., the viscosity of the propylene-based polymer becomes high, and it becomes difficult to knead with the peroxide. On the other hand, when the temperature exceeds 300 ° C., the propylene-based polymer deteriorates, which is not preferable. The degraded propylene-based polymer obtained in the present invention can be used as a material for extrusion molding and injection molding.

[0012]

The present invention will be described below in more detail with reference to examples and comparative examples. In addition, the symbol of the compound used in an Example shows the following compounds. DCP: Dicumyl peroxide (purity 100%) BuP: m-bis (α-t-butylperoxyisopropyl) benzene (purity 99%) 25B: 2,5-bis (t-butylperoxy) 2,5
-Dimethylhexane (purity 92%) 25Y: 2,5-bis (t-butylperoxy) 2.5
-Dimethylhexine-3 (purity 90%) H1D: di (1,1-dimethylbutyl) peroxide (purity 90%) H2D: di (1,1,2-trimethylpropyl) peroxide (purity 90%)

Fluidity test of polymer (melt flow rate (abbreviated as MFR in the table): JIS) using melt indexer C-5059D manufactured by Toyo Seiki Seisaku-sho, Ltd.
1. Load at 230 ° C. for 10 minutes according to K7210.
It was measured under the condition of 16 kg. Odor test: 10 g of degraded pellets were placed in a 50 ml glass container, sealed and placed in a thermostat at 40 ° C. for 1 hour. The odor was confirmed, and the odor level was determined in the following three stages. Level 1: Almost no odor. Level 2: Smell is slightly observed. Level 3: There is a pungent odor.

Example 1 A polypropylene manufactured by Sumitomo Chemical Co., Ltd. (Noblen H501)
A master batch was manufactured by mixing 50 g of H1D with 950 g of MFR 3.5). Noblen H501 10
22.5 g of the master batch (0.1 kg as peroxy bond per kg of polypropylene after mixing).
0005 mol, equivalent to 112 ppm), and a plastic extruder VSK manufactured by Nippon Placon Co., Ltd.
-50, and kneaded at 190 to 200 ° C for an average residence time of 5 minutes to produce pellets. The polymer fluidity and odor of the pellets were measured according to the methods described above. The test results are shown in Table 1.

[0015]

[Table 1]

Example 2 A masterbatch was prepared in Example 1 using H2D instead of H1D, and this masterbatch was then used as a peroxy bond per kg of polypropylene at 0.00
It carried out like Example 1 except having mixed the quantity equivalent to 05 mol. The results are shown in Table 1.

Examples 3 and 4 The masterbatch of H1D produced in Example 1 was mixed with polypropylene in an amount corresponding to the amount shown in Table 1 and supplied to the plastic extruder.
Then, it carried out according to Example 1. The results are shown in Table 1.

COMPARATIVE EXAMPLES 1-4 Master batches were prepared in Example 1 using the various peroxides shown in Table 1 in place of H1D, and these master batches were then each added in an amount of 0.0005 mol peroxy bond per kg of polypropylene. Was mixed and supplied to the plastic extruder, and then the same operation as in Example 1 was carried out. Table 1 shows the results.
It was shown to. As for the odor, a pungent odor peculiar to each peroxide decomposition product was recognized. From Table 1, it can be seen that when the propylene-based polymer is degraded using the peroxide specified in the present invention as compared with the peroxide used conventionally, the effect of improving the fluidity of the polymer is comparable and the decomposition of the peroxide is comparable. It can be seen that the odor can be significantly reduced.

[0019]

According to the process for producing a degraded propylene polymer of the present invention, a specific peroxide is used to improve the fluidity (MFR) of the polymer and efficiently produce a degraded propylene polymer having a low odor. Obtainable.

Claims (1)

[Claims] 1. A method for producing a degraded propylene-based polymer by heating a propylene-based polymer and a peroxide, characterized in that di-t-hexyl peroxide is used as the peroxide. Method.