Block polymer and antistatic agent comprising the same

Details Block polymer and antistatic agent comprising the same Block polymer and antistatic agent comprising the same

2001-12-12

2003-04-22

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...

C525S192000, C525S193000, C525S194000, C525S195000, C525S078000, C525S079000, C525S296000, C525S298000

Reexamination Certificate

active

06552131

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a block polymer and an antistatic agent comprising the same.
More particularly, it relates to a block polymer for use as an antistatic agent suited for use in coated or printed moldings and an antistatic agent comprising the same.
BACKGROUND ART
Any block polymer having a structure comprising repetitions of a polyolefin block and a hydrophilic polymer block is not known in the art.
On the other hand, the method generally employed for providing a thermoplastic resin such as a polyolefin with permanent antistatic properties comprises incorporating an antistatic agent such as a polyetheresteramide in the resin and a method for improving the compatibility between a polyolefin and a polyetheresteramide which comprises using an acid-modified high-molecular-weight polyolefin in combination is known (e.g. Japanese Kokai Publication Hei-01-16234, Japanese Kokai Publication Hei-03-290464, etc.).
However, this method is disadvantageous in that the polyetheresteramide is hardly oriented on the surface of moldings of a crystalline polyolefin and, in extrusion molding or compression molding in which no shearing action is produced, it is necessary to add a large amount of the antistatic agent, such as a polyetheresteramide.
Furthermore, the compatibility is insufficient, which raises the problem of mold contamination and/or roll contamination in the step of molding.
In addition, since a compatibilizer is required in large amounts to raise the compatibility with the resin, the mechanical strength and moldability of the resin decrease, and this problem has not been solved as yet.
Consequently, an antistatic agent which might give polyolefin resin compositions excellent in permanent antistatic properties and mechanical strength at low addition levels irrespective of molding method has been earnestly demanded.
SUMMARY OF THE INVENTION
As a result of intensive investigations made by them to solve the above problems, the present inventors found that a block polymer comprising a polyolefin and a hydrophilic polymer is finely dispersed in resins, in particular polyolefins, without requiring any compatibilizer, giving thermoplastic resin compositions which gives moldings having permanent antistatic properties at low block polymer addition levels even when they are produced by a method involving no shearing and which are also excellent in mechanical strength, and that the block polymer has good compatibility, hence causes no mold contamination or roll contamination. These findings have led to completion of the present invention.
Thus, the present invention provides a block polymer (A)
which has a structure such that blocks of a polyolefin (a) and blocks of a hydrophilic polymer (b) having a volume resistivity of 10
5
to 10
11
&OHgr;·cm are bonded together alternately and repeatedly;
an antistatic agent comprising said block, polymer (A);
a resin composition comprising said polymer (A) and a thermoplastic resin (B); and
a molded product obtainable by coating or printing a molding comprised of a resin composition containing said block polymer (A).
DETAILED DISCLOSURE OF THE INVENTION
The block polymer (A) of the invention has a structure such that blocks of (a) and blocks of (b) are bonded together alternately and repeatedly via at least one bonding mode selected from the group consisting of ester bonding, amide bonding, ether bonding, urethane bonding and imide bonding.
Usable as the blocks of polyolefin (a) constituting the block polymer (A) are a polyolefin (a1) having carbonyl groups (preferably a carboxyl group; hereinafter the same shall apply) at both polymer termini, a polyolefin (a2) having hydroxyls at both polymer termini and a polyolefin (a3) having amino groups at both polymer termini.
Further, a polyolefin (a4) having a carbonyl group at one polymer terminus, a polyolefin (a5) having a hydroxyl at one polymer terminus and a polyolefin (a6) having an amino group at one polymer terminus can be used.
Among them, the carbonyl-containing polyolefins (a1) and (a4) are preferred in view of their easy modifiability.
Usable as (a1) are those derived from a polyolefin (a0) comprising a polyolefin modifiable at both termini as a main constituent (content not less than 50%, preferably not less than 75%) by carbonyl group introduction at both termini.
Usable as (a2) are those derived from (a0) by hydroxyl group introduction at both termini.
Usable as (a3) are those derived from (a0) by amino group introduction at both termini.
As (a0), there may be mentioned polyolefins obtainable by polymerization of one or a mixture of two or more of olefins containing 2 to 30 carbon atoms (preferably olefins containing 2 to 12 carbon atoms, in particular preferably propylene and/or ethylene) and low-molecular-weight polyolefins obtainable by thermal degradation of high-molecular-weight polyolefins (polyolefins obtainable by polymerization of olefins containing 2 to 30 carbon atoms, preferably 2 to 12 carbon atoms, in particular preferably polypropylene and/or polyethylene).
The number average molecular weight (hereinafter referred to as Mn for short) of (a0) as determined by gel permeation chromatography is generally 800 to 20,000, preferably 1,000 to 10,000, in particular preferably 1,200 to 6,000.
The measurement conditions for Mn are as follows (hereinafter, all Mn data are those determined under the same conditions).
Apparatus: High temperature gel permeation chromatograph (GPC)
Solvent: Orthodichlorobenzene
Reference material: Polystyrene
Sample concentration: 3 mg/ml
Column temperature: 135° C.
(a0) contains 1 to 40, preferably 1 to 30, in particular preferably 4 to 20, double bonds per 1,000 carbon atoms.
Preferred from the easy modifiability viewpoint are low-molecular-weight polyolefins obtainable by thermal degradation (in particular polyethylene and polypropylene with an Mn of 1,200 to 6,000).
Low-molecular-weight polyolefins obtainable by thermal degradation have an Mn in the range of 800 to 6,000 and contain, on an average, 1.5 to 2 terminal double bonds per molecule [Katsuhide Murata and Tadahiko Makino, Journal of the Chemical Society of Japan, page 192 (1975)].
Such low-molecular-weight polyolefins obtainable by thermal degradation can be obtained, for example, by the method described in Japanese Kokai Publication Hei-03-62804.
Usable as (a4) are those derived from a polyolefin (a00) comprising a polyolefin modifiable at one terminus as a main constituent (content not less than 50%, preferably not less than 75%) by carbonyl group introduction at one terminus.
Usable as (a5) are those derived from (a00) by hydroxyl group introduction at one terminus.
Usable as (a6) are those derived from (a00) by amino group introduction at one terminus.
The (a00) can be obtained in the same manner as (a0) and the Mn of (a00) is generally 2,000 to 50,000, preferably 2,500 to 30,000, in particular preferably 3,000 to 20,000.
The (a00) contains 0.3 to 20, preferably 0.5 to 15, in particular preferably 0.7 to 10, double bonds per 1,000 carbon atoms.
Preferred from the easy modifiability viewpoint are low-molecular-weight polyolefins obtainable by thermal degradation (in particular polyethylene and polypropylene with an Mn of 2,000 to 20,000).
Low-molecular-weight polyolefins obtained by thermal degradation have an Mn in the range of 5,000 to 30,000 and contain, on an average, 1 to 1.5 terminal double bonds per molecule.
The (a0) and the (a00) are generally obtained as a mixture thereof. The mixture of these may be used as such or each may be used after separation and purification. From the production cost viewpoint, however, the mixture is preferably used.
Usable as (a1) are carbonyl-containing polyolefins (a1-1) derived from (a0) by modifying both termini with an &agr;,&bgr;-unsaturated carboxylic acid (anhydride), carbonyl-containing polyolefins (a1-2) derived from (a1-1) by secondary modification with a lactam or amino carboxylic acid, carbonyl-containing polyolefins (a1-3) derived from (a0) by modification by oxidation with oxygen and/or ozone or by oxo pr

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