CA2035571A1 - Method of production shaped articles having excellent impact resistance - Google Patents

Abstract

PATENT APPLICATION
Country : JAPON
No. : 23020 Filed on : 1st February 1990 File : AM 0472 A B S T R A C T
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A METHOD OF PRODUCTION SHAPED ARTICLES
HAVING EXCELLENT IMPACT RESISTANCE
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Company called : ATOCHEM
4 & 8 Cours Michelet La Défense 10 Authorized agent : Pierre POISSON

Inventors : Kuniyoshi ASANO
Tomoyoshi UEMURA
Hiroshi TAKIDA
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The present invention relates a method of producing shaped articles from the composition comprising :
- 50 to 99.5 weight % of a saponified ethylene-vinyl acetate copolymer, - 0.4 to 50 weight % of an ethylene-propylene copolymer, and - 0.1 to 15 weight % of a compatibilizing agent defined in the description.

Description

7 :~

[Prior Art]
Saponitied ethylene-vinyl acetate copolymers are much superior in rigidity, hardness, wear resistance, antistatic property and other aspects to other resins for molding but has a drawback that their impact resistance is not satisfactory.
To cope with such drawback, measures have been taken which consist in incorporation into said sapo-nified copolymers synthetic resins, such as styrene-butadiene copolymer and acrylonitrile-butadiene co-polymer, polyester elastomers, thermoplastic urethane resins, and ethylene copolymers.
[Problems Which the Invention is to Solve]
However, the prior art measures are not always satisfactory from the impact resistance-improving effect viewpoint. For instance, when synthetic rubbers are used, they may undergo thermal degradation during molding or give shaped articles with insufficient weather resistance. When polyester elastomers are used, the shaped articles may encounter chemical : resistance problems.
: Furthermore, thermoplastic urethanes are disadvan-tageous in that they cause marked viscosity increases during molding. Ethylene copolymers are unsatisfactory in long-run moldability. Thus, at present, no prior , r~,~

art method can improve the impact resistance of said saponified copolymers to a satisfact3ry extent.
[Means of Solving the Problems]
As a result of their intensive nvestigations to solve such problems, the present inventors found that the objects of the invention can be accomplished when a composition derived from a saponifie~ ethylene-vinyl acetate copolymer (A) by incorporating therein an ethylene-propylene copolymer elastomer (B) and a graft polymer (C) obtained by grafting an e~hylenically unsaturated carboxylic acid or a der vative thereof to a polyolefin resin and reacting the -esulting grafting product further with a polyamide oli~omer is melt-molded. The present invention has _een completed based on this and other findings.
The saponified ethylene-vinyl --etate copolymer (A) to be employed in accordance wi.h the present invention should have an ethylene ccntent of 20 to 60 mole %, preferably 25 to 55 mole %, with a degree of saponification of its vinyl acetate -omponent being not less than 95 mole %.
With an ethylene content less ,nan 20 mole %, the water resistance is not as high as __sired, while an ethylene content in excess of 60 mole % leads to decreases in rigidity, wear resistance and other ~3~

physical properties. When the degree of saponification or hydrolysis is less than 95 mole ~, the rigidity, hardness and water resistance are sacrificed.
It should be understood that this saponified copolymer may contain small proport~ons of other comonomer ingredients including a-olefins such as propylene, isobutene, a-octene, a-dodecene, a-octa-decene, etc., unsaturated carboxylic acids or salts thereof, partial alkyl esters, complete alkyl esters, nitriles, amides and anhydrides of such acids, and unsaturated sulfonic acids or salts thereof.
The ethylene-propylene copolymer elastomer ~B) is a copolymer elastomer with an ethylene content of 30 to 90 weight % and those species that have a density of about 0.85 to 0.87 g/cm3 and a glass transition point within the range of -50C to -60DC are suited for use in most cases.
It is also possible to use a terpolymer produced by copolymerization of ethylene, propylene and a diene monomer (third component).
For improving the compatibility between (A) and (B), incorporation of (C~ is essent_al in the practice of the invention.
The component (C) is a graft polymer obtainable by grafting an ethylenically unsaturated carboxylic acid 2 ~ ~ 3 or a derivative thereof to a polyolefin resin and reacting this carboxylic acid or derivative thereof with a polyamide oligomer.
This graft polymer can be produced by dissolving or suspending a polyolefin resin in an appropriate sol-vent or putting it in a molten state, activating the polyolefin resin chain with a peroxide or diazo initi-ator, grafting an ethylenically unsaturated carboxylic acid or a derivative thereof thereto to give a polymer and mixing this polymer with a polyamide oligomer in molten state.
For this reaction, Brabender machine, Buss blender, single-screw extruder, Werner and Pfleiderer twin-screw extruder or the like is employed.
The degree of polymerization of the polyolefin resin to be employed is about 350 to 45,000 and prefer-ably about 500 to 1,000. The melt flow rate (230C, load 2160 g; the same applies hereinafter) is about 0.1 to 50 g/10 minutes for all practical purposes.
The reaction ratio of the polyolefin resin to the ethylenically unsa~urated carboxylic acid or a deriva-tive thereof is 100/0.05 through 100/10 and preferably 100/0.05 through 100/3 as expressed on the weight basis.
If the ratio is 100/less than 0.05, the improving ~3~

effect on compatibility will not be sufficient. On the other hand, if the ratio is 100/more than 10, the viscosity will be too high for practical molding.
The degree of polymerization of said polyamide oligomer is 5 to 80, preferably about 15 to 55, for all practical purposes and the reaction ratio is 0.01 to 1 mole and preferably 0.5 to 0.9 mole per mole of the carboxyl group.
As examples of the polyolefin resin, there may be mentioned linear low-density, medium-density or high-density polyethylene, ionomers, ethylene-propylene copolymer, ethylene-acrylic ester copolymer, ethylene-vinyl acetate copolymer and so on. Important for practical purposes are linear low-density polyethylene, low-density polyethylene, ethylene-propylene copolymer and ethylene-vinyl acetate copolymer.
The ethylenically unsaturated carboxylic acid or derivative thereof to be grafted to such a trunk polymer includes, among others r unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid and itaconic acid, and the corresponding anhydrides or half esters.
The polyamlde oligomer can be prepared by the known methods such as addition polymerization of a lactam, polycondensation of an aminocarboxylic acid, 2~3~

polycondensation of a diamine with a dicarboxylic acid, and so on.
Examples of the starting materials for said polyamide oligomer are various lactams such as E-capro-lactam, enantholactam, caprylolactam, laurolactam, ~-pyrrolidone, ~-piperidone, etc., (~-amino acids such as 6-aminocaproic acid, 7-aminoheptanoic acid, 9-amino-nonanoic acid, 11-aminoundecanoic acid, etc., dibasic acids such as adipic acid, glutaric acid, pimellic acid, suberic acid, azelaic acid, sebacic acid, un-decadioic acid, dodecadioic acid, hexadecadioic acid, hexadecenedioic acid, eicosadioic acid, eicosadiene-dioic acid, diglycolic acid, 2,2,4-trimethyladipic acid, xylylenedicarboxylic acid, 1,4-cyclohexanedi-carboxylic acid, terephthalic acid, isophthalic acid, etc., and diamines such as hexamethylenediamine, tetramethylenediamine, nonamethylenediamine, undeca-methylenediamine, dodecamethylenediamine, 2,2,4- (or 2,4,4-)trimethylhexamethylenediamine, bis~4,4'-amino-cyclohexyl)methane, metaxylylenediamine and so on. For molecular weight control, a monoamine such as lauryl-amine or oleylamine can also be used in an appropriate amount.
In the composition of the present invention, t~e proportion of (A~ should be 50 to 99.5 weight % and 2 ~ 3 ~

preferably 60 to 95 weight %, that of (B) should be 0.4 to 50 weight % and preferably 4.5 to 35 weight %, and that of (C) should be 0.1 to 15 weight % and preferably 0.5 to 10 weight %.
hen the proportion of (A) is less than 50 weight % or that of (B~ is over 50 weight %, the rigidity, hardness and wear resistance are adversely affected.
Conversely when the proportion of (A) is over 99.5 weight % or that of (B) is less than 0.4 weight %, the impact resistance-improving effect will not be suf-ficient. When the proportion of (C) is less than 0.1 weight %, the compatibility between (A) and (B) is poor, so that the impact resistance-improving effect decreases. Conversely when the proportion of (C) exceeds 15 weight %, the long-run moldability is adversely affected.
The composition mentioned above is subjected, as such, to molding into desired shaped articles or is preliminarily pelletized and ~hen molded into desired shaped articles.
The method of melt-molding is not limited to any particular technique but may included injection mold-ing, extrusion molding, compression molding, rotary molding, blow molding, fluidized bed dipping and so forth.

2~3~

The temperature of the molten resin should recom-mendably in the range of about 170 to 260C so that the resin can retain an adequate flowability and at the same time thermal degradation can be avoided. In melt-molding, it is possible to incorporate, if neces-sary, known additives, such as a stabilizer, plasti-cizer, filler, colorant, foaming agent, builder, etc., and/or known reinforcements, such as glass fiber, carbon fiber and so on into the composition according to the invention.
The shaped articles obtained by the method men-tioned above can be used in various fields of applica-tion, for example as parts in general machines, appara-tus or appliances, parts in automobiles, ships or aircraft, parts in optical or chronographic instru-ments, parts in electric appliances and so forth.
In addition, the shaped articles according to the invention are useful as packaging materials, such as sheets, films and bottles. In such use, the oxygen barrier property of the saponified ethylene-vinyl acetate copolymer can be exhibited as a characteristic property.
In such use, the shaped articles ac-ording to the invention are used not only in the form of single layer shaped articles but also in the form of laminates in ~3~7~

combination with various thermoplastic resins such as polyolefins, polyesters, nylons and so on. The shaped articles may be stretched uniaxially or biaxially for practical use thereof, as necessary.
~Effects]
In accordance with the present invention, the impact resistance OI the saponified ethylene-vinyl acetate copolymer ~A) can be markedly improved by incorporation thereinto of the ethylene-propylene copolymer elastomer (B) and the specific graft polymer ~C) .
[Examples]
The following examples are further illustrative of the composition of the present invention. In the following descript-on, all parts and % are by weight unless otherwise indicated.
Preparation of samples Saponified ethvlene-vinvl acetate co~olymer Sample E-l E-2 E-3 E-4 -Ethylene content 30 34 40 45 ~mole %) Degree of saponificat_on of vinyl acetate componen~ 99.7 99.4 99. 2 ga, 7 (~ole %) -2 ~

Ethylene-propylene copolvmer elastomer Density ~lass transi-Sample (g/cm~) tion point P-1 Ethylene-propylene copolymer elastomer with ethyiene 0.86 -55 content 50~
P 2 Ethylene-propylene copolymer elastomer with ethylene 0.87 -52 content 67%

Graft polymer Sample G-l G-2 G-3 G-4 Trunk polymer (a) Linear low- Linear poly- Ethylene- Ethylene-density ethylene vinyl acetate propylene co-polyethyler.e co~olymer ~ith polymer with vinyl acetate ethylene content :2% content 12%
MFR ~g/10 min.) (12.5) (7.8) (4 5) (8.0) Unsaturated Maleic Maleic Maleic Maleic carboxylic acid (b) anhydride anhydride anhydride anhydride Polyamide oligomer ~-Caprolac~am ~-Caprolactam Hexamethyiene- ~-Caprolactam (c) oligomeroligomer diamine/-dipic oligomer (P : 25)(P : 40) acid oli~omer (P : 24) (p : 24) (a)/(b) (weight 100/2.1 100/2.5 100/;.~ 100/2.9 Compo- ratio) sition ratio (c)/(b) (mole 1/22/2.5 1.4/1.3 0.9/2.9 ratio) , . _ Examples 1 through :~ and Comparative Examples 1 and 2 The compositions of ~A), (B1 and (C~ as specified in Table 1 were eac;~ mixed well in a powder form in a Henschel mixer, then dried in a hot-air drying chamber and fed to an injection molding machine (shot weight 3.5 ounces) for injection molding under the following molding conditions: nozzle temperature 220C, front temperature 200C, rear temperature 22C, mold tempera-ture C, injection pressure 1,200 ~g/cm2 and cycle 35 seconds.
The test specimens thus obtained were measured for their physical properties. The results are set forth in Table 1.
Table 1 Blending ratio Izod imPact strenqth Example Material E/P/G Notched Unnotched ~kg cm/cm) (Note 2) 1 P-1 75/Z0/5 7.5 20/20 2 P-2 65/25/10 8.0 20/20 3 P-1 80/10/10 8.5 20/20 4 P-2 60/30/10 8.5 20/20 : E-1 P-1 80/15/5 7.5 20/20 6 P-2 90/8/2 6.4 18/20 7 P-2 45/40/15 8.5 16/20 ~3~3~

Ta~le 1 (continued) Blending ratio Izod impact strenqth Example Material E/P/G Notched Unnotched (kg~cm/cm) (Note 2) ., 8 P-1 90/2/8 6.2 18/20 G-Z
E-l 9 P-1 75/10/15 6.5 18/20 _ G-1 P-2 94.5/5/~.5 6.4 17/20 Compara-tive 1 E-l 100 3.6 1/20 Example 2 p 1 74/26 3.2 4/20 Note 1) Impact strength measurements were made after maintaining the test specimens in an absolute.dry condition at 20C
according to ASTM 0256.
Note 2) Number of survivals/number of tests.

[Effects]
Shaped articles produced from the composition comprising (A), (B~ and (C) according to the invention have markedly improved impact resistance without the moldability of the saponified ethylene-vinyi acetate copolymer or the appearance and other aspects of shaped articles being impaired to any substantial extent.

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Claims (3)

1. A method of producing shaped articles having excellent impact resistance which comprises melt-molding a composition derived from a saponified ethyl-ene-vinyl acetate copolymer (A) by incorporating therein an ethylene-propylene copolymer elastomer (B) and a graft polymer (C) obtained by grafting an ethyl-enically unsaturated carboxylic acid or a derivative thereof to a polyolefin resin and reacting the resulting grafting product further with a polyamide oligomer.

2. A method as claimed in Claim 1, wherein the proportion of the saponified ethylene-vinyl acetate copolymer (A) is 50 to 99.5 weight %, that of the elastomer (B) is 0.4 to 50 weight % and that of the graft polymer (C) is 0.1 to 15 weight %.

3. Detailed Description of the Invention The present invention relates to a method of producing shaped articles of high quality by melt-molding a composition comprising a saponified ethylene-vinyl acetate copolymer and an ethylene-propylene copolymer elastomer incorporated in said saponified copolymer.