DK141664B - Process for preparing a graft copolymer. - Google Patents

Description

(11) FOREIGN AFFAIRS 141664 DENMARK 15.1 lnt-c'-s c 08 F 273/02 § (21) Application no. 3995/75 (22) Inteven cton 19 · Jul. 1975 (23) Disagreement 19 * Jul. 1973 (44) The application was forwarded and most frequently received on 19 May 1980

Dl THE RECTORATE FOR

PATENT AND TRADEMARKET (3 °) PHorft requested from it

27- Jul. 1972 »275682, US

(7i) the STANDARD OIL COMPANY, Midland Building, Cleveland 15, Ohio, US.

(72) Inventor: June Temple Duke, 28649 Jackson Road, Chagrin Palls, Ohio, US: Dorothy Clair Prem, 4761 Dalehridge Road * Warrensville Heights,

Ohio, US. ~ (74) Clerk during blessed treatment;

Hofman-Bang & Boutard Engineering Company.

(64) Process for preparing a graft copolymer.

The invention relates to a process for producing a graft copolymer of the kind set forth in the preamble of claim 1.

The known graft copolymers prepared using known methods of the kind set forth in the preamble of claim 1, cf. eg. the disclosure of United States Patent No. 3,426,102, suffers from the disadvantage that their core layer strength is relatively poor, rendering these copolymers unsuitable for a variety of applications.

SUMMARY OF THE INVENTION It is an object of the invention to provide a process for the preparation of a graft copolymer of the kind given in the preamble of claim 1 and 2, in which the graft copolymers formed must exhibit a greater graft impact strength than the graft copolymers prepared using the known methods. of this kind.

The method according to the invention is characterized by the method of claim 1. Surprisingly, it has been found that the presence of gel in the specified critical range causes the graft impact strength of the resulting graft copolymer to be significantly increased.

The polymeric product prepared by the process of the invention is obtained by polymerizing a larger proportion of an alkenic unsaturated nitrile such as acrylonitrile and a smaller proportion of an ester of an alkenic unsaturated carboxylic acid such as ethyl acrylate in the presence of a pre-formed, gel-containing , a gummy copolymer consisting of a greater proportion of a conjugated diene monomer, butadiene-1,3 or isoprene, and a minor proportion of an alkenically unsaturated nitrile such as acrylonitrile. The rubbery copolymer must contain from 10 to 60% by weight of gel.

The alkenically unsaturated nitriles useful in the invention are the alpha, beta-alkenically unsaturated mononitriles of the structure CH2 = C-CN,

R

wherein R is hydrogen, an alkyl group having between 1 and 4 carbon atoms or a halogen. Such compounds include acrylonitrile, alpha-chloroacrylonitrile, alpha-fluoroacrylonitrile, methacrylonitrile and ethacrylonitrile. The most preferred alkenically unsaturated nitriles are acrylonitrile and methacrylonitrile and mixtures thereof.

The esters of alkenically unsaturated carboxylic acids useful in the invention are the lower alkyl esters of alpha, beta-2-alkenically unsaturated carboxylic acids having the structure CH 2 = C-C00R wherein R1 is hydrogen, an alkyl group having from 1 to 4 carbon atoms or a halogen and wherein R is an alkyl group having from 1 to 6 carbon atoms. Compounds of this type include the methyl acrylate, the ethyl acrylate, the propyl acrylates, the butyl acrylates, the amyl acrylates and the hexyl acrylates; methyl methacrylate, ethyl methacrylate, propyl methacrylates and hexyl methacrylates; methyl-alpha-chloroacrylate and ethyl-alpha-chloroacrylate. Most preferred are methyl acrylate, ethyl acrylate and methyl methacrylate.

The important feature of the novel process of the invention is that the polymeric products are prepared by polymerizing the alkenically unsaturated nitrile and the ester of the alkenically unsaturated carboxylic acid in the presence of a gel-containing, pre-formed copolymer of the conjugating diene monomer and the alkenic unsaturated nitrile. The polymerization is carried out in an aqueous medium and preferably in the presence of an emulsifier and a free-radical polymerization initiator at a temperature of about

0 to 100 ° C, largely in the absence of molecular oxygen.

More specifically, the invention can be illustrated by the polymerization of a mixture of acrylonitrile and ethyl acrylate in the presence of a preformed copolymer of butadiene-1,3 and acrylonitrile to produce a product of excellent impact strength and exceptionally good impermeability to gases and vapors when exposed to the product. these gases and vapors in the form of a film or a thin plate.

The rubbery copolymer of butadiene-1,3 and acrylonitrile preferably contains between 60 and 80% by weight of polymerized butadiene-1,3.

When component (A) is predominantly acrylonitrile, it is preferred that the copolymer (C) contains between 30 and 60% by weight gel, and especially between 25 and 40% by weight gel. When (A) is preferably methacrylonitrile, (C) preferably contains between 15 and 50% by weight, in particular between 25 and 40% by weight gel. In these embodiments of the invention, the polymer exhibits extremely high notch impact strengths, cf. the later tables 1 and 2.

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In the above polymerization, it is preferred to use from about 100 parts of combined acrylonitrile and ethyl acrylate from about 100 parts. 1 to 20 parts of the rubbery copolymer of butadiene-1,3 and acrylonitrile.

The novel polymeric products prepared by the process of the invention are thermoplastic materials which can be thermally formed into many different usable articles in any of the conventional ways used in conjunction with known thermoplastic polymeric materials, such as by extrusion, mill treatment, molding, drawing, blowing, etc. The polymeric products produced by the process of the invention have excellent dissolution resistance and their pitting strength and low permeability to gases and vapors make them very useful in the packaging industry, and are particularly useful in the manufacture of bottles, films and other types of liquid and solid containers. substances.

In the following illustrative examples, unless otherwise indicated, the amount of constituents is expressed in parts by weight.

ΒΚ .'- ίΗΜΡΚΠ '. in A. A series of butadiene-1,3 · and acrylonitrile-based copolymers was prepared in latex form using the following general mixing regulations:

Component Parts butadiene-1.3 70 acrylonitrile azobisisobutyronitrile 0.3 - 0.5 t-dodecyl mercaptan 0.4 - 0.65 soap 1.4 "Daxad 11" (sodium salt of 0.1 naphthalene-sulfonic acid formaldehyde) condensation to) distilled water 200 x 16 Part of the acrylonitrile can be replaced by methacrylonitrile.

Alkali metal salt of a fatty acid or a resin acid.

The polymerization was carried out at between 49 and 60 ° C for a conversion of at least 90%. By varying the initiator and mercaptan in the mixing regulation, the amount of gel in each copolymer varied. The gel assay is a modification of the procedure found in "Polymer Letters", Vol. 1, pages 451-453 (1963) by Purdon and Mate.

A solution of antioxidant was added to the elastomeric latex (about 1.25%)> the rubber was coagulated using alum and washed with water and dried overnight in a vacuum oven at 50 ° C. For the purposes of gel analysis, 0.5 g of 0.01 g of dry rubber was accurately weighed into a dry 114 cm 5 flask and 100 ml of methyl ethyl ketone were added at this stage and one of two essentially equivalent methods used in the following are referred to as (a) static sample and (b) shake sample.

(a) Static sample. The sealed bottle containing the rubber and methyl ethyl ketone was kept at room temperature (20 to 24 ° C) for 72 hours.

(b) Shake test. The sealed bottle was firmly clamped in a mechanical shaker at a 45 ° angle. The bottle and its contents were shaken continuously for 3 hours.

Using Sample (a), extract a 25 ml aliquot from the clear, gel-free liquid. If sample (b) is used, the bottle and contents are centrifuged at a rate of 15,000 rpm for 30 minutes and a 25 ml aliquot is extracted from the clear, gel-free liquid.

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The aliquot of clear liquid was in each case (a) or (b) placed in a dry, clean, tared container, the solvent was removed by evaporation (70 to 77 ° C) and the amount of solid residue was determined gravimetrically, the gel content. of the rubber was calculated as follows: weight of sample - (weight of residue x_4l 100% of sample weight B. A series of graft copolymers were prepared by polymerizing acrylonitrile and methyl acrylate in the presence of some of the rubber latexes which are described under A in this example, using the following general mixing regulation:

Component Parts Acrylonitrile 75 Methyl Acrylate 25 "GAFAC RE 610" X '3 Rubber Latex (A in the pre- (based on dry) weight) "Hemp K110" 0.05 n-octyl mercaptan 1.5 potassium persulfate 0.06 Distilled Water 225 x) "GAFAC RE 610" is an emulsifier consisting of a mixture of R-O- (CH2 CH2 O2 PO3M2 and [R-O- (CH2CH2O-) n] 2PO2M where n is a number between 1 and 40, R is an alkyl or alkaryl group and preferably a nonylphenyl group, and M is hydrogen, ammonia or an alkali metal, which mixture is sold by GAF Corporation, YYj

The tetracalcium salt of ethylene-diamine-tetraacetic acid.

The polymerizations were carried out at 54 to 60 ° C for a conversion of at least 90%.

141664 7

The seed copolymers thus prepared were isolated from their latexes using known agents including coagulation, washing and drying. The graft copolymers were compression molded with sample rod melting, and for each sample, the Izod notch impact strength (kg * m per cm notch) was determined. The results of the Izod samples are given in Table 1 and are graphically depicted in FIG. 1, where the weight percent of gel in the elastomer is depicted along the abscissa, while the Izod shear impact strength (denoted as kg * m / cm notch) is plotted along the ordinate.

TABLE 1

Weight-96 gel in Pode copolymer B

Elastomer A Izod Notch Strength 25 0.087 41 0.806 43 0.686 49 0.735 62 0.337 63 0.561 65 0.201 70 0.114 70 0.212 76 0.147 79 0.071 EXAMPLE 2 A. Rubber-like copolymers of butadiene-1.3 and acrylonitrile were prepared in latex form using the following blending specifications:

Component Parts butadiene-1.3 65 acrylonitrile 35 azobisisobutyronitrile 0.5 141664 8 t-dodecyl-mercaptan 0.6 - 1.25 resin acid soap 1.5 distilled water 200

The polymerizations were carried out to a conversion of at least 84% at 50 ° C. The gel content of each copolymer then used in Part B of this example was determined by the method set forth in Example 1A.

B. Graft copolymers were prepared using rubber leaches from A in this example and methacrylonitrile and methyl methacrylate using the following blending specifications:

Ingredients Parts of methacrylonitrile 95 methyl methacrylate 5 "GAFAC RE 610" 3 rubber latex (A in the foregoing) (dry basis rubber) n-dodecyl mercaptan 0.5 t-butyl peroxy pivalant 0.5 distilled water 200 - 225

The polymerizations were carried out at 60 ° C until at least a 90% conversion was obtained. The seed copolymers were worked up as described in Example 1 and the Izod notch impact strengths were determined. The results are given in Table 2 and are graphically depicted in FIG. 2, where the weight percent of gel in the elastomer is depicted along the abscissa, while the Izod notch impact strength (denoted as kg1m / cm notch) is depicted along the ordinate.

g 141664 TABLE 2

Weight Gel 1 Podecopolymer B

elastomer A Izod notch impact 0 0.240 29 0.370 38 0.370 45 0.267 51 0.207 51 0.261 55 0.278 69 0.109 1