Process for producing acid modified polypropylene resin

Details Process for producing acid modified polypropylene resin Process for producing acid modified polypropylene resin

2002-01-14

2003-05-27

Seidleck, James J. (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Mixing of two or more solid polymers; mixing of solid...

C525S263000, C525S273000, C525S240000, C525S309000, C525S322000

Reexamination Certificate

active

06569950

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a process for producing an acid modified polypropylene resin. More specifically, the present invention relates to (i) a process for producing an acid modified polypropylene resin, according to which process (a) lowering of a molecular weight of a polypropylene resin during a production procedure can be diminished, thereby obtaining an acid modified polypropylene resin having a high molecular weight, (b) an amount of a grafted unsaturated carboxylic acid or a grafted derivative thereof in the obtained acid modified polypropylene resin can be increased, and moreover (c) the productivity of the obtained acid modified polypropylene resin can be increased, and (ii) a process for producing an acid modified polypropylene resin, according to which process (a) an amount of a grafted unsaturated carboxylic acid or a grafted derivative thereof in the obtained acid modified polypropylene resin can be increased, and moreover (b) the productivity of the obtained acid modified polypropylene resin can be increased.
BACKGROUND OF THE INVENTION
In order to make use of characteristic features of a polypropylene resin, said resin is blended or alloyed with a different kind of a polymer, or is combined with an inorganic material to obtain a composite material, or is laminated with a metal.
However, the polypropylene resin has problems that (i) its adhesive property to an inorganic material or a metal is not satisfactory, and (ii) its compatibility with a different kind of a polar group-carrying polymer such as a polyester resin, a polyamide resin, a polyphenylene sulfide resin and a polyphenylene oxide resin is low, and therefore (a) a polymer alloy obtained is insufficient in its impact resistance and mechanical strength, and moreover (b) a surface of an article molded from the alloy is peeled easily.
In order to solve such problems, a modified polypropylene resin has been used. As a process for producing such a modified polypropylene resin, there is known a process comprising the steps of (1) melt-kneading a polypropylene resin, an unsaturated carboxylic acid or a derivative thereof and an organic peroxide in an extruder, and (2) grafting the unsaturated carboxylic acid or the derivative thereof to the polypropylene resin.
However, the present inventors have found that said process has a problem that when a large amount of the organic peroxide is used to increase an amount of a grafted unsaturated carboxylic acid or a grafted derivative, a molecular weight of the polypropylene resin is remarkably lowered during the melt-kneading, and thereby a molecular weight of the grafted polypropylene resin is also remarkably lowered.
In order to diminish remarkable lowering of the molecular weight of the grafted polypropylene resin, there are known (1) a process comprising the step of melt-kneading the above-mentioned components in the presence of styrene (“Design of Practical Polymer Alloy” by Fumio Ide, page 51, edited by KOGYO CHOSAKAI PUBLISHING CO. LTD. (1996)), and (2) a process comprising the step of melt-kneading the above-mentioned components in the presence of divinylbenzene (JP-A 7-173229). However, such processes have a problem that lowering of the molecular weight cannot be sufficiently diminished.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a process for producing an acid modified polypropylene resin, according to which process (a) lowering of a molecular weight of a polypropylene resin during a production procedure can be diminished, thereby obtaining an acid modified polypropylene resin having a high molecular weight, (b) an amount of a grafted unsaturated carboxylic acid or a grafted derivative thereof in the resulting acid modified polypropylene resin can be increased, and moreover (c) the productivity of the resulting acid modified polypropylene resin can be increased.
Another object of the present invention is to provide a process for producing an acid modified polypropylene resin, according to which process (a) an amount of a grafted unsaturated carboxylic acid or a grafted derivative thereof in the resulting acid modified polypropylene resin can be increased, and moreover (b) the productivity of the resulting acid modified polypropylene resin can be increased.
The present inventors have undertaken extensive studies on a process for producing an acid modified polypropylene resin. As a result, it has been found that the above-mentioned objects can be accomplished by using a specific organic peroxide, or using a combination of two kinds of a specific organic peroxide, and thereby, the present invention has been obtained.
The present invention provides a process for producing an acid modified polypropylene resin, which comprises the step of kneading:
(1) 100 parts by weight of a polypropylene resin (A),
(2) 0.1 to 20 parts by weight of an unsaturated carboxylic acid or a derivative thereof (B), and
(3) 0.01 to 20 parts by weight of an organic peroxide (C) having a decomposition temperature of from 50 to 120° C., at which a half-life of the organic peroxide is 1 minute.
According to this process, (a) lowering of a molecular weight of the polypropylene resin during a production procedure can be diminished, thereby obtaining an acid modified polypropylene resin having a high molecular weight, (b) an amount of a grafted unsaturated carboxylic acid or a grafted derivative thereof in the resulting acid modified polypropylene resin can be increased, and moreover (c) the productivity of the resulting acid modified polypropylene resin can be increased.
The present invention also provides a process for producing an acid modified polypropylene resin, which comprises the step of kneading:
(1) 100 parts by weight of a polypropylene resin (A),
(2) 0.1 to 20 parts by weight of an unsaturated carboxylic acid or a derivative thereof (B),
(3) 0.01 to 20 parts by weight of an organic peroxide (C) having a decomposition temperature of from 50 to 120° C., at which a half-life of the organic peroxide is 1 minute, and
(4) 0.01 to 20 parts by weight of an organic peroxide (D) having a decomposition temperature of from 150 to 200° C., at which a half-life of the organic peroxide is 1 minute.
According to this process, (a) an amount of a grafted unsaturated carboxylic acid or a grafted derivative thereof in the resulting acid modified polypropylene resin can be increased, and moreover (b) the productivity of the resulting acid modified polypropylene resin can be increased.
DETAILED DESCRIPTION OF THE INVENTION
The “polypropylene resin” (component (A)) used in the present invention means a propylene homopolymer; a random copolymer of propylene and ethylene, which copolymer has 50 to 99.9% by weight of a polymerized propylene unit (said unit is hereinafter referred to as “propylene unit”); a random copolymer of propylene and an &agr;-olefin having 4 to 12 carbon atoms, which copolymer has 50 to 99.9% by weight of a propylene unit; a heterophasic copolymer of propylene and ethylene, which copolymer has 50 to 99.9% by weight of a propylene unit; a block copolymer comprising a segment of a propylene homopolymer and another segment of a propylene/ethylene random copolymer, which block copolymer has 50 to 99.9% by weight of a propylene unit; or a mixture of two or more polymers mentioned above. Of these, preferred are the propylene homopolymer and the heterophasic copolymer of propylene and ethylene.
The above-mentioned “heterophasic copolymer of propylene and ethylene” means a copolymer obtained by a process comprising the steps of (1) polymerizing propylene to obtain a propylene homopolymer, and (2) copolymerizing propylene and ethylene in the presence of the propylene homopolymer obtained in the above step. In the copolymer obtained, there is no substantial chemical bond between the propylene homopolymer and the copolymer of propylene and ethylene. The copolymer is explained in “Polypropylene Handbook”, by Edward P. Moore, Jr., pages 5 and 92, edited by HANSER Co. Incidentally, the copolymer is usually called a “block PP” or a “block

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