GB1567381A

GB1567381A - Impact of rubber-modified nitrile resins

Info

Publication number: GB1567381A
Application number: GB1477/77A
Authority: GB
Original assignee: Standard Oil Co
Current assignee: Standard Oil Co
Priority date: 1976-01-15
Filing date: 1977-01-14
Publication date: 1980-05-14
Also published as: JPS5287450A; AU503512B2; DE2659467A1; DK15877A; NL7700273A; CA1073143A; FR2338302A1; SE7700395L; AU2100176A; IT1067023B

Description

(54) IMPACT IMPROVEMENT OF RUBBER-MODIFIED NITRILE RESINS (71) We,THE STANDARD OIL COMPANY, a corporation organised under the laws of the State of Ohio, United States of America, of Midland Building, Cleveland, Ohio 44115, United States of America, do hereby declare the invention, for which I/we pray that a patent may be granted to me/us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to rubber-modified nitrile resins having improved impact resistance.

According to the invention there is provided an impact-resistant resin composition comprising an intimate mixture of 100 parts by weight of a resin and from 1 to 30 parts by weight of an impact improver which is an oil said weight being based on the total weight of said resin and said oil and said resin resulting from the polymerization of 100 parts by weight of (a) at least 50% by weight of at least one nitrile having the structure

wherein R is hydrogen, a lower alkyl group having from 1 to 4 carbon atoms, or a halogen and (b) up to 50two by weight based on the combined weights of (a) and (b) of an ester having the structure

wherein R1 is hydrogen, an alkyl group having from 1 to 4 carbon atoms, or a halogen, and R2 is an alkyl group having from 1 to 6 carbon atoms, in the presence of from 1 to 40 parts by weight of (c) a rubbery polymer of a conjugated diene monomer which is butadiene and/or isoprene and optionally a comonomer which is selected from styrene, a nitrile monomer having the structure

wherein R has the foregoing designation, and a monomer having the structure

wherein Rl and R2 have the foregoing respective designations, said rubbery polymer containing from 50 to 100% by weight of polymerized conjugated diene and from 0 to 50% of comonomer.

The preferred impact resistance improvers are those oils which are commonly called essential oils. Some derivatives of the essential oils are also useful in the present invention. A more complete description of the essential oils and their derivatives appears on the Kirk Othmer Encyclopedia of Chemical Technology, second Edition, Volume 14, pages 178-216.

Preferred essential oils of use according to the present invention are clove oil, citral, eugenol, veratrole, citronellal, iso-safrol, cinnamyl alcohol, safrole, cineole, and anisole. It is also within the scope of the invention to use synthetic oils such as 2ethyl hexanoic acid, tributyl phosphate, 2,6-di-t-butyl4-methyl phenol, triethyl phosphate, trimethyl phosphate, p-nonyl phenol and 4-hexyl resorcinol, pbutoxy phenol, epoxidised soya bean oil, benzaldehyde, benzil, benzyl alcohol, 2,4,6tri(t-butyl) phenol and the like. As indicated the oils are used in an amount within the range of 1% to 30% by weight based on the total field of the oil and the rubber-modified highnitrile resin.

The resins, the impact resistance of which is improved according to the invention are made from a number of specified components as indicated above. The monovinyl component is an easter of an olefinically unsaturated car boxylic acid having the structure

wherein R1 is hydrogen, an alkyl group having from 1 to 4 carbon atoms, or a halogen, and R2 is an alkyl group having from 1 to 6 carbon atoms. Compounds of this type include methyl acrylate, ethyl acrylate, the propyl acrylates, the amyl acrylates, and the hexyl acrylates; methyl methacrylate, ethyl methacrylate, the propyl methacrylates, the butyl methacrylates, the amyl methacrylates, and the hexyl methacrylates; methyl alphachloroacrylate and ethyl alpha-chloroacrylate.

Most preferred for use in the present invention are methyl acrylate, ethyl acrylate, methyl methacrylate, and ethyl methacrylate.

The conjugated diene monomers used in the production of the polymer include butadiene- 1,3, isoprene, chloroprene, bromoprene, cyanoprene, 2,3-dimethyl-butadiene-1 ,3, 2ethyl-butadiene-1,3 and 2,3-diethyl-butadiene1,3. Most preferred for the purpose of this invention are butadiene-1,3 and isoprene because of their ready availability and their excellent copolymerization properties.

The olefinically unsaturated nitriles used in the production of the polymers include alpha, neta-olefinicallv unsaturated mononitriles having the structure

wherein R is hydrogen, a lower alkyl group having from 1 to 4 carbon atoms, or a halogen. Such compounds include acrylonitrile, alpha-chloroacrylonitrile, alphafluoro-acrylonitrile, methacrylonitrile and ethacrylonitrile. The most preferred olefinically unsaturated nitriles in the present invention are acrylonitrile and methacrylonitrile and mixtures thereof.

The other monovinyl component copolymerizable with the olefinically unsaturated nitriles includes one or more of the esters of olefinically unsaturated carboxylic acids.

Polymerisates of particular utility in this invention and details of their method of preparation are described in U.S. Patents Nos.

3,426,102 and 3,586,737, these references being incorporated herein in their entirety.

In the production of the resins component (A) are preferably present in an amount from 60 to 90% by weight based on the combined weights of (A),and (B) and the rubbery polymer (C) preferably contain more than 50% by weight of conjugated diene and advantageously from 60 to 90% by weight of the conjugated diene.

The polymerisates used in the process of this invention can contain compounding ingredients and additives, pigments, colourants and stabilizers, as is known in the art, provided that the balance between impact strength, flexural strength, tensile strength, processability, heat disortion temperature and other properties is not affected to such a degree that the article is not longer useful for its intended purpose.

The polymers used in the process of this invention are thermoplastic materials which are easily processed and can be thermoformed into a wide variety of useful articles in any of the conventional ways employed with well known thermoplastic polymeric materials such as by extrusion, milling, molding, drawing and blowing. The polymers resulting from the process of this invention have excellent solvent resistance, including water-frost resistance, and their impact strength and low permeability to gases and vapors make them very useful in the packing industry, and they are particularly useful in the manufacture of bottles, films, envelopes, boxes, and other types of containers for liquids and solids.

In the following examples, which will further illustrate this invention, the amounts of the various ingredients are given in parts by weight unless otherwise specified. The amount of oil added as impact improves is based on the total weight of the oil and the resin.

Example 1 A. A rubber latex was prepared by polymerizing with continuous agitation at 45"C in the substantial absence of oxygen a mixture of the following ingredients: Ingredient Parts acrylonitrile 30 butadiene-1,3 60 emulsifier (Gafac Registered 2.4 Trade Mark) RE-610)* azobisisobutyronitrile 0.3 t-dodecyl mercaptan 0.5 water 200 *A mixture of R-O-(CH2 CH2 O-)nP03 M2 and [R-O4CH2CH2O-)n] 2PO2M wherein n is a number from 1 to 40, R is an alkyl or alkaryl group and preferably a nonyl phenyl group, and M is hydrogen, ammonia or an alkali metal, which composition is sold by GAF corporation.

Before reaction was started, the pH of the mixture was adjusted to about 8 with KOH. The polymerization was carried out for 2216 hours to a conversion of 92% and a total solids of 33.1%.

B. An impact-resistant, gas barrier resin was prepared by polymerization of a mixture of the following ingredients: Ingredient Parts acrylonitrile 75 methyl acrylate 25 rubber solids in the form 9 of latex A (above) potassium persulfate 0.06 emulsifier (Gafrac RE-610) 3 Ingredient Parts modifier (n-dodecyl 1 mercaptan) ethylene diamine tetra 0.05 acetic acid water 200 The pH was adjusted to 7 with NH4 OH.

The polymerization was carried out in the substantial absence of oxygen at 600C for 5 hours so as to produce a conversion of 91% of a latex.

The latex obtained from the polymerization was then coagulated and the resin was dried and compression molded into a bar at 1 500C The molded bar was transparent and found to have a notched Izod impact strength of 1.2 foot pounds per inch of notch and ASTM heat-distortion temperature of 69"C at 264 psi and 75"C at 66 psi by ASTM test D;648-56. The polymer was easily blended in a Brabender plasticorder and at the end of 10 minutes in the plasticorder at 2300C and 35 rpm, a torque reading of 1150 meter grams was obtained for the polymer. A sample of this polymer was compression molded into a sheet and this sheet was found to have a water vapor transmission of 4.51 grams/mil/100 inches2 /24 hours at 90% relative humidity and 100 F by ASTM procedure E-96. The sheet was found to have an oxygen transmission of 0.6 cc/mil/ 100 inches /24 hours/atmosphere by ASTM procedure D1434. The sheet was also found to have a frosting index of 6.4 haze units. Frosting index was obtained by measuring the haze or refracted light off the piece of the sheet. The sheet was then subjected to a temperature of 50"C and 100% relative humidity for 16 hours at which time the haze was redetermined. The difference in the haze readings is the frost index. The haze readings were done on a Hunter Laboratories color difference meter model D-25-P.

Example 2 Samples of the resin described in Example 1 were blended with various amounts of clove oil in an efficient mixer such as a rubber mill, Banbury, extruder or ko-kneader.

The blends were compression molded into test bars and the notched Izod impact values were determined on the bars including a control bar containing no clove oil. The following results were obtained: Clove Oil, % Notched Izod Impact Strength 0 1.2 foot pounds per inch of notch 5 2.2 foot pounds per inch of notch 10 3.6 foot pounds per inch of notch 20 2.8 foot pounds per inch of notch Example 3 The procedure of Example 2 was repeated using 10% of clove oil with the following results: Eugenol, % Notched Izod Impact Strength 0 1.2 foot pounds per inch of notch 10 3.4 foot pounds per inch of notch Example 4 The procedure of Example 3 was repeated using citral in place of eugenol. The notched Izod impact for the citral-containing resin was 5.1 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control.

Example 5 The procedure of Example 4 was repeated using veratrole in place of citral. The notched Izod impact strength for the veratrole-containing resin was 2.1 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control.

Example 6 The procedure of Example 5 was repeated using citronellal in place of veratrole. The notched Izod impact strength for the cittronellal-containing resin was 2.8 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control.

Example 7 The procedure of Example 6 was repeated using cinnamyl alcohol: in place of citronellal.

The notched Izod impact strength for the cinnamyl alcohol-containing resin was 2.1 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control.

Example 8 The procedure of Example 7 was repeated using isosafrol instead of cinnamyl alcohol.

The notched Izod impact strength for the iso-safrol-containing resin was 1.9 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control.

Example 9 The procedure of Example 8 was repeated using iso-eugenol instead of iso-safrol. The notched Izod impact strength for the isoeugenol-containing resin was 2.1 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control.

Example 10 The procedure of Example 9 was repeated using trans cinnamaldehyde instead of isoeugenol. The notched Izod impact strength for the trans cinnamaldehyde-containing resin was 1.6 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control.

Example 11 The procedure of Example 10 was repeated using safrole instead of trans cinnamaldehyde.

The notched Izod impact strength for the safrole-containing resin was 1.6 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control.

Example 12 The procedure of Example 11 was repeated using 4 parts of cineole instead of 10 parts of safrole. The notched Izod impact strength for the cineole-containing resin was 2.3 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control.

Example 13 The procedure of Example 11 was repeated using 8 parts of anisole instead of 10 parts of safrole. The notched Izod impact strength of the anisole-containing resin was 2.9 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control.

Example 14 A. A rubber latex was prepared by polymerizing with continuous agitation at 450C in the substantial absence of oxygen a mixture of the following ingredients: Ingredient Parts acrylonitrile 30 Butadiene-1,3 60 emulsifier (Gafac RE-610)* 2.4 azobisisobutyronitrile 0.3 t-dodecyl mercaptan 0.5 water 200 *A mixture of R-Q+cH2cH2o-)npO3M2 and [R-O < CH2 CH2 O-)n] 2 PO2 M wherein n is a number from 1 to 40, R is an alkyl or alkaryl group and preferably a nonyl phenyl group, and M is hydrogen, ammonia or an alkali metal, which composition is sold by GAF Corporation.

Before reaction was started, the pH of the mixture was adjusted to about 8 with KOH. The polymerization was carried out for 22 and 1/2 hours to a conversion of about 92% and a total solids of about 33.1%.

B. An impact-resistant, gas barrier resin was prepared by polymerization of a mixture of the following ingredients: Ingredient Parts acrylonitrile 75 methyl acrylate 25 rubber solids in the 9 form of latex A (above) potassium persulphate 0.06 emulsifier (Gafac RE-610) 3 modififer (n-dodecyl mercaptan) ethylene diamine 0.05 tetra acetic acid water 200 The PH was adjusted to 7 with NH4 OH.

The latex obtained from the polymerization was then coagulated and the resin was dried and compression molded into a bar at 1 500C.

The molded bar was transparent and found to have a notched Izod impact strength of 1.2 foot pounds per inch of notch and ASTM heat-distortion temperatures of 69"C at 264 psi and 75"C at 66 psi at ASTM test D-648-56.

The polymer was easily blended in a Brabender plasticorder and at the end of 10 minutes in the plasticorder at 2300C and 35 rpm, a torque reading of 1150 meter grams was obtained for the polymer. A sample of this polymer was compression molded into a sheet and this sheet was found to have a water vapor transmission of 4.51 grams/mil/100 inches2 /24 hours at 90So relative humidity and 100 F by ASTM procedure E-96. The sheet was found to have an oxygen transmission of 0.6 cc/mil/100 inches 2/24 hours/atmosphere by ASTM procedure D-1434. The sheet was also found to have a frosting index of 6.4 haze units. Frosting index was obtained by measuring the haze or refracted light off the piece of the sheet. The sheet was then subjected to a temperature of 50"C and 100% relative humidity for 16 hours at which time the haze was redetermined. The difference in the haze readings is the frost index.

The haze readings were done in a Hunter Laboratories color difference meter model D-25-P.

Example 15 Samples of the resin described in Example 14 were blended with various amounts of triethvl phosphate in an efficient mixer such as a rubber mill, banbury, extruder or ko-kneader. The blends were compression molded into test bars and the notched Izod impact values were determined on the bars including a control bar containing no oil. The following results were obtained: Triethyl Phosphate,% Notched Izod Impact Strength 0 1.2 foot pounds per inch of notch 8 3.2 foot pounds per inch of notch 10 5.3 foot pounds per inch of notch 15 7.8 foot pounds per inch of notch Example 16 The procedure of Example 15 was repeated using 10% of 2ethyl hexanoic acid in place of 10% of triethyl phosphate with the following results: 2-Ethyl Hexanoic Acid, % Notched Izod Impact Strength 0 1.2 foot pounds per inch of notch 10 3.1 foot pounds per inch of notch Example 17 The procedure of Example 16 was repeated using 2,4-di-t-butyl phenol in place of 2-ethyl hexanoic acid. The notched Izod impact strength for the 2,4-di-t-butyl phenol-containing resin was 1.5 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control.

Example 18 The procedure of Example 17 was repeated using trimethyl phosphate in place of 2,4di-t-butyl phenol. The notched Izod impact strength for the trimethyl phosphate-containnig resin was 2.1 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control.

Example 19 The procedure of Example 18 was repeated using tributyl phosphate in place of trimethyl phosphate. The notched Izod impact strength for the tributyl phosphate containing resin was 2.3 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control.

Example 20 The procedure of Example 19 was repeated using 2,6-di-t-butyl4-methyl phenol in place of tributyl phosphate. The notched Izod impact strength for the 2,6-di-t-butyl4-methyl phenolcontaining resin was 2.9 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control.

Example 21 The procedure of Example 20 was repeated using p-nonyl phenol instead of 2,6-di-t-butyl4-methylphenol. The notched Izod impact strength for the p-nonyl phenol-containing resin was 3.1 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control.

Example 22 The procedure of Example 21 was repeated using 4-hexyl resorcinol instead of p-nonyl phenol. The notched Izod impact strength for the 4-hexyl resorcinol-containing resin was 2.1 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control.

Example 23 The procedure of Example 22 was repeated using p-butoxy phenol instead of 4-hexyl resorcinol. The notched Izod impact strength for the p-butoxy phenol-containing resin was 2.1 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control.

Example 24 The procedure of Example 23 was repeated using an epoxidized soybean oil instead of pbutoxy phenol. The notched Izod impact strength for the epoxidized soybean oil-containing resin was 7.9 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control.

Example 25 The procedure of Example 24 was repeated using benzaldehyde instead of epoxidized soybean oil. The notched Izod impact strength of the benzaldehyde-containing resin was 2.0 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control.

Example 26 The procedure of Example 25 was repeated using benzil instead of benzaldehyde. The notched Izod impact strength for the benzilcontaining resin was 1.7 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control.

Example 27 The procedure of Example 26 was repeated using benzyl alcohol instead of benzil. The notched Izod impact strength for the benzyl alcohol-containing resin was 2.0 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control.

Example 28 The procedure of Example 27 was repeated using benzyl ether instead of benzyl alcohol.

The notched Izod impact strength for the benzyl ether-containing resin was 2.8 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control.

Example 29 The procedure of Example 28 was repeated using 5% of 2,4,6-tri(t-butyl) phenol instead of 10% of benzyl ether. The notched Izod impact strength for the 2,4,6-tri(t-butyl) phenol-containing resin was 2.9 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control.

WHAT WE CLAIM IS: 1. An impact-resistant resin composition comprising an intimate mixture of 100 parts by weight of a resin and from 1 to 30 parts by weight of an impact improver which is an oil said weight being based on the total weight of said resin and said oil and said resin resulting from the polymerization of 100 parts by weight of (A) at least 50% by weight of at least one nitrile having the structure

wherein R is hydrogen, a lower alkyl group having from 1.

to 4 carbon atoms, or a halogen and (B) up to 50% by weight based on the combined weights of (A) and (B) of an ester having the structure

wherein Rl is hydrogen, an alkyl group having from 1 to 4 carbon atoms, or a halogen, and R2 is an alkyl group having from 1 to 6 carbon atoms in the presence of from 1 to 40 parts by weight of (C) a rubbery polymer of a conjugated diene monomer which is butadiene and/or isoprene and optionally a comonomer which is selected from styrene, a nitrile monomer having the structure

wherein R has the foregoing designation, and a monomer having the structure

wherein Rl and

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. using 2,4-di-t-butyl phenol in place of 2-ethyl hexanoic acid. The notched Izod impact strength for the 2,4-di-t-butyl phenol-containing resin was 1.5 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control. Example 18 The procedure of Example 17 was repeated using trimethyl phosphate in place of 2,4di-t-butyl phenol. The notched Izod impact strength for the trimethyl phosphate-containnig resin was 2.1 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control. Example 19 The procedure of Example 18 was repeated using tributyl phosphate in place of trimethyl phosphate. The notched Izod impact strength for the tributyl phosphate containing resin was 2.3 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control. Example 20 The procedure of Example 19 was repeated using 2,6-di-t-butyl4-methyl phenol in place of tributyl phosphate. The notched Izod impact strength for the 2,6-di-t-butyl4-methyl phenolcontaining resin was 2.9 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control. Example 21 The procedure of Example 20 was repeated using p-nonyl phenol instead of 2,6-di-t-butyl4-methylphenol. The notched Izod impact strength for the p-nonyl phenol-containing resin was 3.1 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control. Example 22 The procedure of Example 21 was repeated using 4-hexyl resorcinol instead of p-nonyl phenol. The notched Izod impact strength for the 4-hexyl resorcinol-containing resin was 2.1 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control. Example 23 The procedure of Example 22 was repeated using p-butoxy phenol instead of 4-hexyl resorcinol. The notched Izod impact strength for the p-butoxy phenol-containing resin was 2.1 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control. Example 24 The procedure of Example 23 was repeated using an epoxidized soybean oil instead of pbutoxy phenol. The notched Izod impact strength for the epoxidized soybean oil-containing resin was 7.9 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control. Example 25 The procedure of Example 24 was repeated using benzaldehyde instead of epoxidized soybean oil. The notched Izod impact strength of the benzaldehyde-containing resin was 2.0 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control. Example 26 The procedure of Example 25 was repeated using benzil instead of benzaldehyde. The notched Izod impact strength for the benzilcontaining resin was 1.7 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control. Example 27 The procedure of Example 26 was repeated using benzyl alcohol instead of benzil. The notched Izod impact strength for the benzyl alcohol-containing resin was 2.0 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control. Example 28 The procedure of Example 27 was repeated using benzyl ether instead of benzyl alcohol. The notched Izod impact strength for the benzyl ether-containing resin was 2.8 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control. Example 29 The procedure of Example 28 was repeated using 5% of 2,4,6-tri(t-butyl) phenol instead of 10% of benzyl ether. The notched Izod impact strength for the 2,4,6-tri(t-butyl) phenol-containing resin was 2.9 foot pounds per inch of notch compared to 1.2 foot pounds per inch of notch for the control. WHAT WE CLAIM IS:

1. An impact-resistant resin composition comprising an intimate mixture of 100 parts by weight of a resin and from 1 to 30 parts by weight of an impact improver which is an oil said weight being based on the total weight of said resin and said oil and said resin resulting from the polymerization of 100 parts by weight of (A) at least 50% by weight of at least one nitrile having the structure

wherein R is hydrogen, a lower alkyl group having from 1.

wherein R has the foregoing designation, and a monomer having the structure

wherein Rl and

R2 have the foregoing respective designations, said rubbery polymer containing from 50 to 100% by weight of polymerized conjugated diene and from 0 to 50% of comonomer.

2. An impact-resistant composition comprising an intimate mixture of 100 parts by weight of a resin and from 1 to 30 parts by weight of an impact improver which is a synthetic oil said weight being based on the total weight of said resin and said oil, said oil being selected from 2-ethyl hexanoic acid, tributyl phosphate, 2 ,6-di-t-butyl-4,methyl phenol, triethyl phosphate, trimethyl phosphate, pnonyl phenol, 4-hexyl resorcinol, p-butoxyphenol, epoxidised soya bean oil, benzaldehyde, benzil, benzyl alcohol, 2,4,6-tri(t-butyl) phenol or a similar oil and said resin resulting from the polymerization of 100 parts by weight of (A) at least 50% by weight of least one nitril6 having the structure

wherein R is hydrogen, a lower alkyl group having from 1 to 4 carbon atoms, or a halogen and (B) up to 50% by weight based on the combined weights of (A) and (B) of an ester having the structure

wherein Rl is hydrogen an alkyl group having from 1 to 4 carbon atoms, or a halogen, and R2 is an alkyl group having from 1 to 6 carbon atoms, in the presence of from 1 to 40 parts by weight of (C) a rubbery polymer of a conjugated diene monomer which is butadiene and/or isoprene and optionally a comonomer which is selected from styrene, a nitrile monomer having the structure

wherein R has the foregoing designation and a monomer having the structure

3. An impact-resistant resin composition comprising an intimate mixture of 100 parts by weight of a resin and from 1 to 30 parts by weight of an impact improver which is an essential oil said weight being based or. the total weight of said resin and said oil said resin resulting from the polymerization of 100 parts by weight of (A) at least 50% by weight of at least one nitrile having the structure

wherein R1 is hydrogen, an alkyl group having from 1 to 4 carbon atoms, or a halogen, and R2 is an alkyl group having from 1 to 6 carbon atoms in the presence of from 1 to 40 parts by weight of (C) a rubbery polymer of a conjugated diene monomer which is butadiene and/or isoprene and optionally a comonomer which is selected from styrene, a nitrile monomer having the structure

where in R has the foregoing designation, and a monomer having the structure

wherein R1 and R2 have the foregoing respective designations, said rubbery polymer containing from 50 to 100% by weight of polymerized conjugated diene and from 0 to 50% of comonomer.

4. A composition as claimed in claim 3 in which the essential oil is selected from clove oil, eugenol, citral, veratrole, citronellal, cinnamyl alcohol, iso safrol, cineole, safrole and anisole.

5. A composition as claimed in any of claims 1 to 4 wherein (A) is acrylonitrile.

6. A composition as claimed in claim 2 substantially as herein described with reference to any one of Examples 15 to 28.

7. A composition as claimed in claim 3 substantially as herein described with reference to any one of Examples 2 to 13.

8. A method of making a rubber-modified nitrile resin of improved resistance which comprises incorporating in such resin an impact improver which is an oil in an amount of 1% to 30% by weight based on the total weight of the resin and the impact improver said resin being one resulting from the polymerization of the resin being one resulting from the polymerization of the resin components as defined in claim 1.

9. A method of making a rubber-modified nitrile resin of improved impact resistance which comprises incorporating in such resin an oil as defined in claim 2 in an amount of 1 to 30% by weight based on the total weight of the resin and the oil said resin being one resulting from the polymerization of the resin components as defined in claim 2.

10. A method of making a rubber-modified nitrile resin of improved impact resistance which comprises incorporating in such resin an oil as defined in claims 3 and 4 in an amount of 1 to 30% by weight based on the total weight of the resin and of the oil, said resin being one resulting from the polymerization of the resin components defined in claim 3.

11. A method as claimed in claim 9 substantially as herein described with reference to any one of Examples 15 to 28.

12. A method as claimed in claim 10 substantially as herein described with reference to any one of Examples 2 to 13.

13. A resin of improved impact resistance when made by a method as claimed in either of claims 9 or 11.

14. A resin of improved impact resistance when made by a method as claimed in either ofclaims 10 or 12.