WO2016195601A1

WO2016195601A1 - Polymer compositions and processes for producing the same

Info

Publication number: WO2016195601A1
Application number: PCT/TH2015/000033
Authority: WO
Inventors: Kwampian SUTHEP; Phonthong RONNAPA; Worawan Laptaptimthong; JAIKAEW.Charungkit; Pichapob Karoonngampan
Original assignee: Irpc Public Company Limited
Priority date: 2015-06-04
Filing date: 2015-06-04
Publication date: 2016-12-08

Abstract

Disclosed herein is a process for preparing a polymer composition comprising the steps of contacting about 40 to about 70 parts by weight of a cross-linked natural rubber with about 30 to about 60 parts by weight of styrene thereby forming a graft natural rubber; and compounding about 5 to about 70 parts by weight of the graft natural rubber with about 30 to about 95 parts by weight of a polystyrene thereby forming a polymer composition.

Description

POLYMER COMPOSITIONS AND PROCESSES FOR PRODUCING THE

SAME

TECHNICAL FIELD

Disclosed is a process for preparing polymer compositions comprising a natural rubber styrene copolymer and a polystyrene, e.g., a high impact polystyrene, and products thereof.

BACKGROUND

Polystyrene has found widespread commercial use owing to its useful physical properties and low cost. Unmodified polystyrene is a hard brittle material. As such, it is well suited to applications where its brittleness is acceptable, for instance, the production of protective packaging, containers, lids, bottles, trays, etc. However, for applications where more resilient materials are required polystyrene can be polymerized with one or more elastomeric polymers to increase the materials toughness and impact absorption. For example, polystyrene can be polymerized with an amount of a rubber to produce a stronger and more resilient copolymer. Such rubber modified polystyrene compositions are typically referred to as high impact polystyrenes (HIPS).

There exist a great variety of HIPS that vary in molecular weight, ratio of styrene to rubber, and other features, all of which can influence a HIPS composition. Furthermore, varying the type of rubber, altering amounts of rubber and polystyrene copolymers used in a HIPS composition, and adjusting amounts of other additives and reactions conditions can all influence the physical and chemical properties of HIPS. In addition, in recent years there has been an increasing demand for environmentally friendly polymers derived from natural and sustainable resources, such as natural rubber-based polymer compositions. Thus, an ongoing need exists for novel environmentally friendly HIPS compositions that possess certain physical properties tailored to meet a specific end-use. The present disclosure is directed towards a process for preparing novel HIPS compositions that address these needs and have related benefits. SUMMARY

In accordance with an aspect of the present disclosure, a process for preparing a polymer composition comprises: contacting about 40 to about 70 parts by weight of a cross-linked natural rubber with about 30 to about 60 parts by weight of styrene thereby forming a graft natural rubber; and compounding about 5 to about 70 parts by weight of the graft natural rubber with about 30 to about 95 parts by weight of a polystyrene thereby forming the polymer composition. The polystyrene can be a high impact polystyrene. The process can further comprise contacting a natural rubber with a divinyl benzene, thereby forming the cross-linked natural rubber. For instance, about 100 parts by weight of the natural rubber can be contacted with about 0.1 to about 1 parts by weight of the divinyl benzene. The cross-linked natural rubber can have a total solids content of between about 30% and about 50% by weight and a gel fraction between about 80% and about 90%. Contacting the cross-linked natural rubber and the styrene can comprise adding the styrene to the cross-linked natural rubber at a temperature of at least about 50° C. In some embodiments, the styrene is added to the cross-linked natural rubber over the course of at least about 4 hours at a temperature between about 50° C and about 70° C and then the temperature is maintained at between about 72° C and about 80° C for at least about 30 minutes.

In several embodiments, about 40 to about 60 parts by weight of the cross-linked natural rubber is contacted with about 40 to about 60 parts by weight of the high impact polystyrene.

The process can further comprise flocculating the graft natural rubber at a temperature between about 70° C and about 90° C thereby forming a powdered graft natural rubber. Floccularing the graft natural rubber can comprise contacting the graft natural rubber with magnesium sulfate. Between about 20 and about 40 parts by weight of the powdered graft natural rubber can be compounded with about 60 to about 80 parts by weight of a polystyrene. Compounding can further comprise adding between about 0.01 to about 3 parts by weight of a lubricant, for instance, calcium stearate, silicone oil, or ethylene bis(stearamide).

In accordance with an aspect of the present disclosure, a process for preparing a polymer composition comprises: contacting 100 parts by weight of a natural rubber with about 0.1 to about 1 parts by weight of a divinyl benzene thereby forming a cross-linked natural rubber, wherein the cross-linked natural rubber has a total solids content of between about 30% and about 50% by weight and a gel fraction between about 80% and about 90%; adding about 30 to about 60 parts by weight of styrene to about 40 to about 70 parts by weight of the vulcanized natural rubber at a temperature of at a temperature between about 50° C and about 70° C and then maintaining the temperature at between about 72° C and about 80° C for at least two hours thereby forming a graft natural rubber; contacting the graft natural rubber with magnesium sulfate at a temperature between about 70° C and about 90° C thereby forming a powdered graft natural rubber; and compounding between about 20 and about 40 parts by weight of the powdered graft natural rubber with about 60 to about 80 parts by weight of a high impact polystyrene thereby forming a polymer composition.

In accordance with an aspect of the present disclosure, a polymer composition comprises about 5 to about 70 parts by weight of a graft natural rubber and about 30 to about 95 parts by weight of a polystyrene, wherein the graft natural rubber comprises about 30 to about 60 parts by weight of styrene and about 40 to about 70 parts by weight of a cross-linked natural rubber. The polystyrene can be a high impact polystyrene. The cross-linked natural rubber can comprise about 100 parts by weight of a natural rubber and about 0.1 to about 1 parts by weight of a divinyl benzene. The graft natural rubber can comprise about 45 to about 55 parts by weight of styrene and about 45 to about 55 parts by weight of a cross-linked natural rubber. In a number of embodiments, the polymer composition comprises about 20 to about 40 parts by weight of a graft natural rubber and about 60 to about 80 parts by weight of a high impact polystyrene.

The polymer composition can further comprise a lubricant.

The polymer composition can exhibit an Izod notched impact of between about 25 and about 55 Kg cm/cm ; a tensile strength of between about 180 and about 200 Kg/cm²; and/o a gloss of about 70 to about 95 GU measured according to ASTM D523.

In accordance with an aspect of the present disclosure, a polymer composition comprises about 20 to about 40 parts by weight of a graft natural rubber and about 60 to about 80 parts by weight of a high impact polystyrene, wherein the graft natural rubber comprises about 50 parts by weight of styrene and about 50 parts by weight of a cross-linked natural rubber, wherein the cross-linked natural rubber comprises about 1 part by weight of divinyl benzene and 100 parts by weight of a natural rubber and the polymer composition exhibits an Izod notched impact of between about 25 and about 55 Kg cm/cm and a gloss of about 70 to about 95 GU.

DETAILED DESCRIPTION

Unless specified otherwise, the terms "comprising" and "comprise" as used herein, and grammatical variants thereof, are intended to represent "open" or "inclusive" language such that they include recited elements but also permit inclusion of additional, un-recited elements.

As used herein, the term "about", in the context of measurement values, conditions, concentrations of components, etc., means +/- 5% of the stated value, or +/- 4% of the stated value, or +/- 3% of the stated value, or +/- 2% of the stated value, or +/- 1% of the stated value, or +/- 0.5% of the stated value, or +/- 0% of the stated value. Throughout this disclosure, certain embodiments may be disclosed in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the disclosed ranges. Accordingly, the description of a range should be considered to have specifically disclosed all the possible sub-ranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range.

Throughout this disclosure, the term "exemplary" should be interpreted in the context of representative non-limiting embodiments (e.g., representative examples), which are provided herein for purpose of aiding understanding.

The present disclosure is directed towards high impact polystyrene (HIPS) compositions prepared using a natural rubber and possessing good impact absorption properties. The present disclosure is also directed toward the preparation of polymer compositions, comprising a cross-linked natural rubber copolymerized with styrene and compounded with a polystyrene, e.g., a HIPS.

The natural rubber used as a raw material for the production of the polymer compositions described herein can be any natural rubber. Suitable examples of natural rubbers include field latexes, ammonia-treated latexes, centrifuged latexes, deproteinized latexes, and latexes derived from any combination thereof.

The natural rubber can have an average molecule weight between about 500,000 amu to about 2,000,000 amu. In certain embodiments, the natural rubber can have an average molecular weight between about 500,000 amu to about 1 ,800,000 amu; about 500,000 amu to about 1,600,000 amu; about 500,000 amu to about 1,500,000 amu; about 600,000 amu to about 1,500,000 amu; about 700,000 amu to about 1,500,000 amu; about 700,000 amu to about 1,400,000 amu; about 800,000 amu to about 1,400,000 amu; or about 870,000 amu to about 1,310,000 amu.

Various well known and conventional polymerization techniques can be used to prepare the cross-linked natural rubber. For example any of the bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, radiation polymerization and photo-polymerization reactions can be employed. In certain embodiments, the cross-linked natural rubber is prepared using bulk polymerization

The natural rubber can be cross-linked prior to polymerization with styrene using one or more suitable multi-functional monomers. Suitable multi-functional monomers can contain two or more polymerizable groups, such as olefins. In certain embodiments, the multi-functional monomers contains 2, 3, 4, 5, or more olefins. Examples of suitable cross-linking agents include divinyl benzene, divinyl naphthalenes, trivinyl benzene, alkyl divinyl benzenes having from 1 to 4 alkyl groups of 1 to 2 carbon atoms substituted in the benzene nucleus, and alkyl trivinyl benzenes having 1 to 3 alkyl groups of 1 to 2 carbon atoms substituted on the benzene nucleus. In certain embodiments the crosslinking agent is a divinyl benzene such as 1 ,2-divinyl benzene, 1,3-divinyl benzene, 1,4-divinyl benzene, and combinations thereof. In certain embodiments, the divinyl benzene further comprises 1 ,2-ethylvinylbenzene, 1,3-ethylvinylbenzene, 1 ,4-ethylvinylbenzene, and combinations thereof. Depending on the extent of cross-linking desired, about 0.1 to about 5 part by weight of the cross-linking agent can be used per about 100 parts by weight of natural rubber. In certain embodiments about 0.1 to about 4.5 by parts weight; about 0.1 to about 4.0 by parts weight; about 0.1 to about 3.5 by parts weight; about 0.1 to about 3.0 by parts weight; about 0.1 to about 2.5 by parts weight; about 0.1 to about 2.0 by parts weight; about 0.1 to about 1.5 by parts weight; about 0.1 to about 1.0 by parts weight; about 0.1 to about 0.9 by parts weight; about 0.1 to about 0.8 by parts weight; about 0.1 to about 0.7 by parts weight; about 0.2 to about 0.7 by parts weight; about 0.3 to about 0.7 by parts weight; about 0.4 to about 0.7 by parts weight; or about 0.4 to about 0.6 by parts weight of cross-linking agent is used per 100 parts by weight of natural polymer. In the examples below 0.5 parts by weight of divinyl benzene is reacted with 100 parts by weight of natural rubber.

The reaction between the cross-linking agent and the natural rubber can take place in the presence of one or more radical polymerization initiators, such as chemical radical initiators, ultra-violet light, high-energy radiation, high temperature and combinations thereof.

Suitable chemical radical initiators include, but are not limited, to those based on peroxide, peroxyester and peroxycarbonate, hydroperoxide, peroxyketals, azide, azido and azo containing compounds or combinations thereof. In certain embodiments, the radical initiator is a hydroperoxide.

Exemplary chemical radical initiators include, but are not limited, to, dicumyl peroxide; n-butyl-4,4-di(t-butylperoxy)valerate; 1 , 1 -di(t-butylperoxy)3,3,5- trimethylcyclohexane; 2,5-dimethyl-2,5-di(t-butylperoxy)hexane; di-t-butyl peroxide; di-t-amyl peroxide; t-butyl peroxide; t-butyl cumyl peroxide; 2,5-dimethyl-2,5-di(t- butylperoxy)hex-3-yne; di(2-t-butyl-peroxyisopropyl)benzene; dilauroyl peroxide; dibenzoyl peroxide; t-butyl hydroperoxide; benzoyl peroxide; azobisisobutyronitrile; l,l'-azobis(cyclohexanecarbonitrile) and combinations thereof In certain embodiments, the radical initiator is t-butyl hydroperoxide.

The amount of the desired chemical radical initiator will depend upon the particular initiator chosen as well as the other reaction conditions. Generally speaking, enough of the initiator should be utilized to provide some improvement to reaction process conditions (e.g., a reduction in required temperature) or realized product yield(s). The selection of such an amount is well within the skill of a person of ordinary skill in the art. In certain embodiments, about 0.0001 to about 10 parts by weight; from about 0.001 to about 5 parts by weight; from about 0.001 to about 4 parts by weight; from about 1 to about 4 parts by weight; or from about 1 to 3 parts by weight of the chemical radical initiator can be used as the chemical radical initiator for every about 100 parts by weight of the natural rubber in the cross-linking reaction.

In the examples below 2 parts by weight of t-butyl hydroperoxide is used for each 100 parts by weight of the natural rubber as the chemical radical initiator in the cross- linking reaction.

The cross-linking reaction yield, purity, and/or ease of use can be improved by the addition of one or more reaction additives. Such reaction additives include, but are not limited, to, antioxidants, metal salts, and emulsifiers.

Exemplary antioxidants include, but are not limited, to alpha-hydroxy ketones, substituted ascorbic acids, sulfinic acids, glucose, glyceraldehyde, galactose, lactose, maltose, hydroxyacetone, 2-hydroxy-2-phenylacetophenone, ascorbyl palmitate, toluene sulfinic acid, mixtures thereof, and the like. In certain embodiments, the antioxidant is a primary antioxidant, such as one or more sterically hindered phenols and/or mixed phenol type antioxidants. In certain embodiments, the antioxidant is a secondary antioxidant, such as one or more phosphite, e.g., organo-phosphite, type antioxidants. In certain embodiments, the antioxidant is combination of a primary type and a secondary type antioxidant.

In certain embodiments, about 0.07 to about 0.42 parts by weight of the antioxidant is used per about 100 parts by weight of the natural rubber in the cross-linking reaction. In certain embodiments, about 0.10 to about 0.39 parts by weight; about 0.13 to about 0.35 parts by weight; about 0.16 to about 0.32 parts by weight; about 0.22 to about 0.32 parts by weight; or about 0.25 to about 0.32 parts by weight of the antioxidant is used per about 100 parts by weight of the natural rubber in the cross-linking reaction. In the examples below, 0.28 parts by weight of lactose is used for every 100 parts by weight of the natural rubber as the antioxidant in the cross-linking reaction.

Exemplary metal salts include, but are not limited, to salts of transition elements, including those of Groups VIb, Vllb, VIII, lb and lib of the Periodic Table of the Elements, and combinations thereof. Chloride, bromide, iodide, hydroxide, sulfate, nitrate, and cyanide salts of iron, cobalt, manganese, nickel, chromium, copper and zinc can be used. In certain embodiments, the metal salt is iron(II)sulfate, iron(II)chloride, iron(II)bromide, iron(II)iodide, iron(II)hydroxide, iron(II)cyanide, iron(II)nitrate, and combinations thereof.

In certain embodiments, about 0.001 to about 0.006 parts by weight of the metal salt is used per about 100 parts by weight of the natural rubber in the cross-linking reaction. In certain embodiments, about 0.002 to about 0.006 parts by weight; about 0.002 to about 0.005 parts by weight; or about 0.003 to about 0.005 parts by weight of the metal salt is used per about 100 parts by weight of the natural rubber in the cross- linking reaction.

In the examples below, 0.004 parts by weight of iron(II)sulfate pentahydrate is used for each 100 parts by weight of the natural rubber as the metal salt in the cross-linking reaction.

Exemplary emulsifiers include salts of fatty acids containing from 4 to 24 carbon atoms, or from 10 to 22 carbon atoms, such as ammonium, lithium, sodium, potassium, rubidium, or cesium salts of rosin acids, oleic acid, palmitic and stearic acid, lauric acid, myristic acid, arachidic acid, castor acids and the like.

In certain embodiments, about 0.5 to about 2.0 parts by weight of the emulsifier is used per about 100 parts by weight of the natural rubber in the cross-linking reaction. In certain embodiments, about 0.5 to about 1.8 parts by weight; about 0.5 to about 1.6 parts by weight; about 0.5 to about 1.4 parts by weight; about 0.6 to about 1.4 parts by weight; about 0.6 to about 1.2 parts by weight; about 0.6 to about 1.0 parts by weight; about 0.7 to about 1.0 parts by weight; or about 0.7 to about 0.9 parts by weight of the emulsifier is used per about 100 parts by weight of the natural rubber in the cross- linking reaction. In certain embodiments, the fatty acid salt can be created in situ by the addition of the fatty acid and a suitable base to the reaction mixture. Suitable bases include, but are not limited, to hydroxide salts of Group IA or Group IIA metals. In such instances, the selection and amount of the base is well within the skill of a person of ordinary skill in the art. In certain embodiments, the base is lithium hydroxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, and combinations thereof.

In instances where the fatty acid salt is created in situ, about 0.5 to about 2.0 parts by weight of the fatty acid and about 0.1 to about 0.5 parts by weight of the base are used per about 100 parts by weight of the natural rubber in the cross-linking reaction. In certain embodiments, about 0.5 to about 1.8 parts by weight; about 0.5 to about 1.6 parts by weight; about 0.5 to about 1.4 parts by weight; about 0.6 to about 1.4 parts by weight; about 0.6 to about 1.2 parts by weight; about 0.6 to about 1.0 parts by weight; about 0.7 to about 1.0 parts by weight; or about 0.7 to about 0.9 parts by weight of the fatty acid and about 0.1 to about 0.4 parts by weight; about 0.1 to about 0.3 parts by weight; or about 0.1 to about 0.4 parts by weight of base are used per about 100 parts by weight of the natural rubber in the cross-linking reaction.

In the examples below, 0.85 parts by weight of oleic acid and 0.20 parts by weight of potassium hydroxide are used for each 100 parts by weight of the natural rubber as the emulsifier in the cross-linking reaction.

The cross-linking reaction can be conducted by the addition of the natural rubber to a suitable reaction vessel. To this reaction vessel can then be added the cross-linking agent and optionally the antioxidant. The temperature in the reaction vessel can then be increased. In certain embodiments, the temperature is increased at least to 40° C; at least 50° C; at least 60° C; or at least 70° C. In certain embodiments, the temperature is increased to about 30 to about 100° C; about 40 to about 100° C; about 50 to about 100° C; about 50 to about 90° C; about 50 to about 80° C; or about 60 to about 80° C. Once the temperature in the reaction vessel has reached the desired temperature, the catalyst and optionally the emulsifier can be added. In certain embodiments, the catalyst and/or optionally the emulsifier are added in one portion. In certain embodiments, the catalyst and/or optionally the emulsifier are continuously added over a period of about 1 hour. The reaction can then be allowed to proceed at the desired temperature for between about 1 to 10 hours thereby forming the cross- linked natural rubber. In certain embodiments, the reaction can then be allowed to proceed for between about 1 to 9 hours; 2 to 9 hours; 3 to 9 hours; 4 to 9 hours; 5 to 9 hours; 6 to 9 hours; or 6 to 8 hours.

In the examples below, the natural rubber, lactose, FeS0₄-7H20, tetrasodium pyrophosphate, and divinyl benzene were added to a reaction vessel and the temperature within the reaction vessel is heated to 70° C. Once the temperature within the reaction vessel reached 70° C, the oleic acid, potassium hydroxide, and t- butyl hydroperoxide were added by slow addition over a period of one hour. The reaction was then allowed to proceed at 70° C for seven hours.

Exemplary cross-linked natural rubbers prepared according to the process described herein can have the physical properties presented in Table 1 below.

Table 1.

Properties Unit PVNR-001 PVNR-002

TSC % 41.47 41.10

SOL % 15.63 15.86

Gel % 84.37 84.14

Deg. Swelling gel - 0.13 0.13

Depending on the cross-linking reaction parameters, such as choice of reagents, reagent stoichiometry, reaction temperature, reaction time, etc., the physical properties of the cross-linked natural rubber can vary. The selection of such reaction parameters is well within the skill of a person of ordinary skill in the art.

In certain embodiments, the cross-linked natural rubber has a total solids content between about 30% and about 50%; about 32% and about 48%; about 34% and about 46%; about 36% and about 44%; about 38% and about 44%; about 40% and about 44%; or about 40% and about 42%.

In certain embodiments, the cross-linked natural rubber has a gel fraction between about 80%) and about 90%; about 81% and about 89%; about 82% and about 88%; about 83% and about 87%; or about 83% and about 85%.

The cross-linked natural rubber can then be polymerized with styrene thereby forming the graft natural rubber. Any polymerization technique known to those of skill in the art can be utilized to polymerize the cross-linked natural rubber and the styrene. Suitable polymerization techniques include, but are not limited to, bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, radiation polymerization and photo-polymerization reactions. In certain embodiments, the cross-linked natural rubber and the styrene are emulsion polymerized. Styrene is widely commercially available and as used herein the term "styrene" includes substituted styrenes (e.g., alpha-methyl styrene), ring-substituted styrenes, such as p-methylstyrene, as well as unsubstituted styrene. In certain embodiments, the styrene has the following formula:

wherein Ri and R₂ are selected from the group consisting of lower alkyl or alkenyl groups of from, for example, 1 to 6 carbon atoms and hydrogen, each R is selected from the group consisting of halogen, hydrogen and lower alkyl groups of from, for example, 1 to 6 carbon atoms, and n is an integer of from 0 to 5.

The amount of cross-linked natural rubber and styrene used in the polymerization reaction can influence the physical and chemical properties of the polymerization product. The selection of which is well within the skill of a person of skill in the art can be affected, in part, by the desired application of the polymer composition and cost considerations. In certain embodiments about 40 to about 70 parts by weight of the cross-linked natural rubber is reacted with about 30 to about 60 parts by weight of styrene. In certain embodiments about 40 to about 70 parts by weight; about 40 to about 65 parts by weight; about 40 to about 60 parts by weight; about 40 to about 55 parts by weight; about 45 to about 55 parts by weight; or about 48 to about 53 parts by weight of the cross-linked natural rubber is reacted with about 30 to about 60 parts by weight; about 35 to about 60 parts by weight; about 40 to about 60 parts by weight; about 40 to about 55 parts by weight; about 45 to about 55 parts by weight; or about 48 to about 52 parts by weight of styrene.

In the examples below, 50 parts by weight of cross-linked natural rubber is used for each 50 parts by weight of styrene in the emulsion polymerization reaction with styrene. The reaction between the cross-linked natural rubber and styrene can take place in the presence of one or more radical polymerization initiators, such as a chemical radical initiator, ultra-violet light, high-energy radiation, high temperature and combinations thereof.

Suitable chemical radical initiators include, but are not limited, to those mentioned above and persulfate salts, e.g., of ammonium persulfate, lithium persulfate, sodium persulfate, potassium persulfate, iron(II)persulfate, copper(II)persulfate and hydrates thereof.

In certain embodiments, about 0.0001 to about 10 parts by weight; from about 0.001 to about 5 parts by weight; from about 0.001 to about 4 parts by weight; from about 0.1 to about 3 parts by weight; from about 0.1 to about 2 parts by weight; from about 0.1 to about 1 parts by weight; or from about 0.1 to about 0.5 parts by weight of the chemical radical initiator can be used for every about 50 parts by weight of the cross- linked natural rubber.

In the examples below, 0.31 parts by weight of potassium persulfate is used for each 50 parts by weight of the cross-linked natural rubber in the emulsion polymerization reaction with styrene.

In certain embodiments, the polymerization of the cross-linked natural rubber and the styrene is conducted in the presence of one or more emulsifiers. Exemplary emulsifiers include, but are not limited, ionic emulsifiers, non-ionic emulsifiers, and combinations thereof. In certain embodiments, the emulsifier is selected from the group consisting of SN 100 (a mixture of oleic acid and steric acid), rosin soap, oleic acid, stearic acid soap, and combinations thereof. In certain embodiments, about 0.1 to about 2.0 parts by weight of the emulsifier is used per about 50 parts by weight of the cross-linked natural rubber in the polymerization reaction. In certain embodiments, about 0.1 to about 2.0 parts by weight; about 0.3 to about 2.0 parts by weight; about 0.5 to about 2.0 parts by weight; about 0.7 to about 2.0 parts by weight; about 0.8 to about 2.0 parts by weight; about 0.8 to about 1.8 parts by weight; about 0.8 to about 1.6 parts by weight; about 1.0 to about 1.6 parts by weight; about 1.2 to about 1.6 parts by weight; or about 1.4 to about 1.6 parts by weight of the emulsifier is used per about 50 parts by weight of the cross-linked natural rubber in the polymerization reaction.

In the examples below, 1.5 parts by weight of SN 100 (a mixture of oleic acid and steric acid) is used for each 50 parts by weight of the cross-linked natural rubber in the emulsion polymerization reaction with styrene.

In certain embodiments, the polymerization reaction between the cross-linked natural rubber and styrene takes place in the presence of a base. Suitable bases include lithium hydroxide, sodium hydroxide, potassium hydroxide, cesium hydroxide, ammonium hydroxide, and combinations thereof. In certain embodiments, the polymerization reaction between the cross-linked natural rubber and styrene takes place in the presence sodium hydroxide, potassium hydroxide, and ammonium hydroxide. In certain embodiments, about 0.01 to about 2.0 parts by weight of the base is used per about 50 parts by weight of the cross-linked natural rubber in the polymerization reaction. In certain embodiments, about 0.01 to about 1.7 parts by weight; about 0.01 to about 1.4 parts by weight; about 0.01 to about 1.3 parts by weight; about 0.01 to about 1.0 parts by weight; about 0.01 to about 0.7 parts by weight; about 0.1 to about 0.7 parts by weight; about 0.2 to about 0.7 parts by weight; about 0.2 to about 0.6 parts by weight; about 0.2 to about 0.5 parts by weight; or about 0.2 to about 0.4 parts by weight of the base is used per 50 parts by weight of the cross-linked natural rubber in the polymerization reaction. In instances where the cross-linked natural rubber and styrene are emulsion polymerized, the polymerization reaction can take place in water, e.g., deionized water. In certain embodiments, about 50 to about 200 parts by weight; about 60 to about 200 parts by weight; , about 70 to about 200 parts by weight; about 90 to about 200 parts by weight; about 100 to about 200 parts by weight; about 1 10 to about 200 parts by weight; about 1 10 to about 190 parts by weight; about 110 to about 180 parts by weight; about 120 to about 180 parts by weight; about 130 to about 180 parts by weight; about 130 to about 170 parts by weight; about 130 to about 170 parts by weight; or about 140 to about 180 parts by weight water is used for every 50 parts by weight of cross-linked natural rubber.

In the examples below, 140 parts by weight of deionized water is used for each 50 parts by weight of the cross-linked natural rubber in the emulsion polymerization reaction with styrene.

In instances in which the cross-linked natural rubber and styrene are emulsion polymerized, the emulsion polymerization can be conducted by adding the cross- linked natural rubber, base, and water to a reaction vessel. The temperature inside the reaction vessel can then be heated to at least about 50° C. In certain embodiments, the temperature inside the reaction vessel is heated to at least about 55° C; at least about 60° C; or at least about 65° C. In certain embodiments, the temperature inside the reaction vessel is heated to between about 40° C and about 80° C; about 40° C and about 75° C; about 45° C and about 75° C; about 50° C and about 75° C; about 60° C and about 75° C; or about 65° C and about 75° C; or about 65° C and about 70° C.

A portion of the styrene, e.g., 5%-20% of the total amount to be used in the emulsion polymerization reaction, and the chemical radical initiator can then be added to the reaction vessel and the resulting mixture can be allowed to stir for at least about 20 minutes. In certain embodiments the resulting mixture is allowed to stir for at least about 25 minutes or at least about 30 minutes. In certain embodiments, the reaction mixture is allowed to stir for between about 10 minutes and about 50 minutes; about 10 minutes and about 40 minutes; about 20 minutes and about 40 minutes; or about 35 minutes and about 35 minutes. Then the remaining styrene and the emulsifier can be continuously charged into the reaction vessel over a period of at least about two hours. In certain embodiments, the remaining styrene and the emulsifier are continuously charged into the reaction vessel over a period of at least about 3 hours; about 4 hours; about 5 hours; or about 6 hours. In certain embodiments, the remaining styrene and the emulsifier are continuously charged into the reaction vessel over a period between about 1 hour and about 10 hours; about 2 hours and about 10 hours; about 3 hours and about 10 hours; about 4 hours and about 10 hours; about 4 hours and about 9 hours; about 5 hours and about 9 hours; about 5 hours and about 8 hours; or about 5 hours and about 7 hours.

Upon complete addition of the remaining styrene and emulsifier the reaction mixture can be allowed to react for at least about 10 minutes after which time the reaction temperature can be increased to between about 72° C and about 80° C and allowed to react at this temperature for at least about 30 minutes.

In certain embodiments, upon complete addition of the styrene and emulsifier, the reaction mixture is allowed to react for at least about 15 minutes; about 20 minutes; about 25 minutes; or about 30 minutes. In certain embodiments, upon complete addition of the styrene and emulsifier, the reaction mixture can be allowed to react for between about 1 minute and about 50 minutes; about 10 minutes and about 50 minutes; about 10 minutes and about 40 minutes; or about 20 minutes and about 40 minutes.

In certain embodiments, upon complete addition of the styrene and emulsifier to the reaction mixture and being allowed to react for the period of time described above, the reaction temperature can be increased to between about 72° C and about 80° C; about

73° C and about 79° C; about 74° C and about 78° C; or about 74° C and about 77°

C and allowed to react at this temperature for at least about 30 minutes; about 1 hour; about 2 hours; or about 3 hours. In certain embodiments, the reaction is allowed to react within any of the aforementioned temperature ranges for about 30 minutes to about 5 hours; about 30 minutes to about 4 hours; about 1 hour to about 4 hours; or about 2 hours to about 4 hours. In the examples below, the cross-linked natural rubber and base were added to a reaction vessel and the temperature within the reaction vessel was heated to 68° C. Once the temperature within the reaction vessel reached 68° C, 20% of the styrene to be used in the polymerization and the catalyst were added to the reaction vessel and allowed to stir at 68° C for 30 minutes. The remainder of the styrene and the emulsifier were then continuously charged over a period of 6 hours. Upon completing the addition of the styrene and emulsifier, the reaction was allowed to stir at 68° C for 30 minutes. The reaction temperature was then increased to 75° C and the reaction was stirred at this temperature for a period of three hours thereby forming the graft natural rubber.

Exemplary graft natural rubber prepared according to the process described herein can have the physical properties presented in Table 2 below. Table 2.

Graft Natural Rubber Properties

Properties Unit

001 002 pH - 10.06 10.06

TSC % 42.34 42.27

TB - 7.52 7.52

Density g/cm³ 0.987 0.987

Graft ratio % 59.98 59.76

IV of free SAN - 0.08 0.07

Coagulum % 0.02 0.02

Residue Styrene monomer (R-monomer) % 0.26 0.37

Natural Rubber Content %

PVNR (% NR) 50 50

One or more flocculating agents can be added to flocculate the graft natural rubber.

Flocculation is generally defined as a process whereby colloids are formed in suspension (or as suspended in a liquid). During flocculation, fine particulates agglomerate or clump together in a floe. In other words, individual dispersed particles agglomerate or cluster together during flocculation. The floe may float up or accumulate at the top of the liquid or settle at the bottom of the liquid, and can be separated or harvested via a filtration process.

The flocculation process or reaction is performed or carried out by reacting the graft natural rubber with one or more flocculating agents and optionally one or more additives. Exemplary flocculating agents include organic salts, inorganic salts, and mineral compounds. Examples of organic salts include, but are not limited, to, compounds such as quaternary ammonium compounds, phosphonium compounds, sulfonium compounds. Other organic salts include, but are not limited, to, primary, secondary and tertiary amine salts. Inorganic salts include, but are not limited, to, any suitable Group I or Group II main group metal cation or any suitable transition metal cation that provides sufficient ionic charge to flocculate the dispersions. Any anion that provides sufficient solubility of the inorganic compound in the liquid carrier may be used. Examples of anions include, but are not limited, to, chloride, bromide, iodide, sulfate, nitrate, perchlorate, chlorate, or phosphate. Examples of inorganic salts include, but are not limited, to, calcium chloride, magnesium chloride, sodium chloride, potassium chloride, lithium chloride, calcium sulfate, magnesium sulfate, potassium sulfate, and lithium sulfate. Mineral compounds include, but are not limited, to, hydrotalcite. About 0.1 to about 10 parts by weight of the flocculating agent can be added per 100 parts by weight of the graft natural rubber in the graft natural rubber flocculation reaction. In certain embodiments, about 0.01 to about 10; about 0.01 to about 9; about 0.01 to about 8; about 0.01 to about 7.0; about 0.1 to about 7.0; about 1.0 to about 7.0; about 2.0 to about 7.0; about 3.0 to about 7.0; about 3.0 to about 6.0; about 3.5 to about 6.0; about 3.5 to about 5.5; about 4.0 to about 5.5; or about 4.3 to about 5.2 parts by weight of the flocculating agent is added per 100 parts by weight of the graft natural rubber in the graft natural rubber flocculation reaction.

In the examples below, 4.3 to 5.2 parts by weight of the magnesium sulfate heptahydrate flocculating agent is used per 100 parts by weight of the graft natural rubber in the flocculating reaction.

One or more additives can be included in the flocculating reaction to improve recovery of the powdered graft natural rubber and/or its physical chemical properties. The selection of the type and amount of the additive is well within the skill of a person of skill in the art and may depend on the desired physical chemical properties of the floe and/or its intended application. Exemplary reaction additives include, but are not limited, to, antioxidants, metal deactivators, and color stabilizers. Exemplary antioxidants include phenol-based antioxidants, such as n-octadecyl 3,5- di-tert-butyl-4-hydroxyhydrocinnamate, neopentanetetrayl tetrakis-(3,5-di-tert-butyl- 4-hydroxyl-hydrocinnamate), di-n-octadecyl 3,5-di-tert-butyl-4-hydroxybenzyl- phosphonate, l,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl-)isocyanurate,

thiodiethylene bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), 1 ,3,5-trimethyl-2,4,6- tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 3,6-di-oxaoctamethylene bis(3- methyl-5-tert-butyl-4-hydroxyhydrocinnamate), 2,6-di-tert-butyl-p-cresol, 2,2'- ethylidene-bis(4,6-di-tert-butylphenol), l,3,5-tris-(2,6-di-methyl-4-tert-butyl-3- hydroxybenzyl)isocyanurate. 1 , 1 ,3-tris-(2-methyl-4-hydroxy-5-tert- butylphenyl)butane, l,3,5-tris-[2-(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyloxy)- ethyl]-isocyanurate, 3,5-di-(3,5-di-tert-butyl-4-hydroxybenzyl)-mesitol, hexa- methylene bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), 1 -(3,5-di-tert-butyl-4- hydroxyanilino)-3,5-di(octylthio)-s-triazine, N.N'-hexamethylene-bisp^-di-tert- butyl-4-hydroxyhydro-cinnamamide), calcium bis(ethyl-3 ,5 -di-tert-butyl-4- hydroxybenzylphosphonate), ethylene bis[3,3-di(3-tert-butyl-4- hydroxyphenyl)butyrate] , octyl 3 ,5-di-tert-butyl-4-hydroxybenzylmercaptoacetate, bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyl)hydrazide, NN^,-bis-[2-(3,5-tert-butyl- 4-hydroxyhydroxocinnamoyloxy)-ethyl] 9-oxamide, neopentanetetrayl tetrakis(3,5-di- tert-butyl-4-hydroxyhydrocinnamate), n-octadecyl 3,5-di-tert-butyl-4- hydroxyhydrocinnamate, l,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxy- benzyl)benzene, 1 ,3,5-tris-(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, 2,6-di- tert-butyl-p-cresol, 2,2'-ethylidene-bis(4,6-di-tert-butylphenol),

poly(dicyclopentadiene-co-p-cresol), and Octolite 1219.

About 0.01 to about 5 parts by weight of the antioxidant can be added per 100 parts by weight of the graft natural rubber in the graft natural rubber flocculation reaction. In certain embodiments, about 0.01 to about 4; about 0.01 to about 3; about 0.01 to about 2; In certain embodiments, about 0.1 to about 2; about 0.1 to about 1.8; about 0.1 to about 1.6; about 0.1 to about 1.4; about 0.3 to about 1.4; about 0.5 to about 1.4; about 0.5 to about 1.2; about 0.7 to about 1.2; about 0.8 to about 1.2; about 0.8 to about 1.1 ; or about 0.9 to about 1.1 parts by weight of the antioxidant is added per 100 parts by weight of the graft natural rubber in the graft natural rubber flocculation reaction.

In the examples below, 1 part by weight of primary antioxidant is user per 100 parts by weight of the graft natural rubber in the flocculating reaction. Exemplary metal deactivators include, but are not limited, to alkali metal or alkaline earth metal hydroxides. In certain embodiments the metal deactivator is an alkali metal hydroxide. In certain embodiments, the alkali metal or alkaline earth metal hydroxides is lithium hydroxide, sodium hydroxide, potassium hydroxide, cesium hydroxide, rubidium hydroxide, calcium hydroxide, magnesium hydroxide, strontium hydroxide, or barium hydroxide. About 0.01 to about 2 parts by weight of the alkali metal or alkaline earth metal hydroxide can be added per 100 parts by weight of the graft natural rubber in the graft natural rubber flocculation reaction. In certain embodiments, about 0.1 to about 1.0; about 0.1 to about 0.9; about 0.1 to about 0.8; about 0.1 to about 0.7; about 0.1 to about 0.6; about 0.2 to about 0.6; about 0.3 to about 0.6; or about 0.4 to about 0.6 parts by weight of the alkali metal or alkaline earth metal hydroxide can be added per 100 parts by weight of the graft natural rubber in the graft natural rubber flocculation reaction.

In the examples below, 0.5 parts by weight of the potassium hydroxide metal hydroxide is used per 100 parts by weight of the graft natural rubber in the flocculating reaction.

Exemplary color stabilizers include, but are not limited, to, alkali metal or alkaline earth metal C₆ - C₂₄ alkyl sulfate salts, alkali metal or alkaline earth metal formaldehyde sulfoxylate salts, alkali metal or alkaline earth metal pyrophosphate salts, alkali metal or alkaline earth metal hydroxides, and combinations thereof.

In certain embodiments, the alkali metal or alkaline earth metal C₆ - C₂₄ alkyl sulfate salt is a lithium, sodium, potassium, rubidium, or cesium salt of lauryl sulfate, cetyl sulfate, octyl sulfate, dodecyl sulfate, and tridecyl sulfate.

About 0.01 to about 0.5 parts by weight of the alkali metal or alkaline earth metal C6 to C24 sulfate salt can be added per 100 parts by weight of the graft natural rubber in the graft natural rubber flocculation reaction. In certain embodiments, about 0.01 to about 0.4; about 0.01 to about 0.3; about 0.01 to about 0.2; about 0.01 to about 0.18; about 0.01 to about 0.16; about 0.01 to about 0.14; about 0.05 to about 0.14; or about 0.07 to about 0.12 parts per weight of the alkali metal or alkaline earth metal C₆ - C₂₄ alkyl sulfate salt can be added per 100 parts by weight of the graft natural rubber in the graft natural rubber flocculation reaction.

In certain embodiments, the alkali metal or alkaline earth metal formaldehyde sulfoxylate salt is a lithium, sodium, potassium, rubidium, or cesium salt of formaldehyde sulfoxylate.

About 0.01 to about 0.5 parts by weight of the alkali metal or alkaline earth metal formaldehyde sulfoxylate salt can be added per 100 parts by weight of the graft natural rubber in the graft natural rubber flocculation reaction. In certain embodiments, about 0.01 to about 0.4; about 0.01 to about 0.3; about 0.01 to about 0.2; about 0.01 to about 0.18; about 0.01 to about 0.16; about 0.01 to about 0.14; about 0.05 to about 0.14; or about 0.07 to about 0.12 parts per weight of the alkali metal or alkaline earth metal formaldehyde sulfoxylate salt can be added per 100 parts by weight of the graft natural rubber in the graft natural rubber flocculation reaction.

In certain embodiments, the alkali metal or alkaline metal earth pyrophosphate salt is a lithium, sodium, potassium, rubidium, or cesium salt of pyrophosphate. About 0.01 to about 0.5 parts by weight of the alkali metal or alkaline earth metal pyrophosphate salt can be added per 100 parts by weight of the graft natural rubber in the graft natural rubber flocculation reaction. In certain embodiments, about 0.01 to about 0.4; about 0.01 to about 0.3; about 0.01 to about 0.2; about 0.01 to about 0.18; about 0.01 to about 0.16; about 0.01 to about 0.14; about 0.05 to about 0.14; or about 0.07 to about 0.12 parts per weight of the alkali metal or alkaline earth metal pyrophosphate salt can be added per 100 parts by weight of the graft natural rubber in the graft natural rubber flocculation reaction.

In certain embodiments, the alkali metal or alkaline earth metal hydroxide is a lithium, sodium, potassium, rubidium, or cesium hydroxide. About 0.01 to about 1.0 parts by weight of the alkali metal or alkaline earth metal hydroxide can be added per 100 parts by weight of the graft natural rubber in the graft natural rubber flocculation reaction. In certain embodiments, about 0.01 to about 0.9; about 0.01 to about 0.8; about 0.01 to about 0.7; about 0.01 to about 0.6; about 0.01 to about 0.5; about 0.01 to about 0.4; about 0.01 to about 0.3; or about 0.1 to about 0.3 parts per weight of the alkali metal or alkaline earth metal hydroxide can be added per 100 parts by weight of the graft natural rubber in the graft natural rubber flocculation reaction. In certain embodiments, one, two, three, four, or more color stabilizers can be added to the flocculation reaction. In such instances, the amount of the color stabilizer can be increased according to the number of color stabilizers used. For example, if two color stabilizers are used each color stabilizer can be added in the graft natural rubber flocculation reaction according to the amounts described above.

In the examples below, 0.21 parts by weight of potassium hydroxide, 0.1 parts by weight of tetrasodium pyrophosphate, and 0.1 parts by weight of sodium dodecyl sulfate are used as color stabilizers per 100 parts by weight of the graft natural rubber in the flocculating reaction.

The process of flocculating the graft natural rubber can comprise the steps of combining the graft natural rubber, the metal deactivator, and antioxidant to produce a latex masterbatch. Water and the flocculating agent can then be added to a reaction vessel and then heated to a temperature of between about 70° C and about 90° C. The latex masterbatch can then be added to the reaction vessel and the reaction can be allowed to proceed for about 15 to 30 minutes at a temperature between about 70° C and about 90° C. The floe formed during the reaction can be collected by filtration. The collected floe can then be dried by heating at 80° C in an oven for 24 hours thereby producing the powdered graft natural rubber. In certain embodiments, the flocculation temperature is between about 75° C and about 90° C; about 80° C and about 90° C; about 82° C and about 90° C; about 82° C and about 88° C; or about 82° C and about 86° C. The polymer composition can be prepared by a variety of methods involving intimate admixing of the powdered graft natural rubber and polystyrene with any additional additives desired in the polymer composition. Suitable procedures include solution blending and melt blending. Examples of equipment used in such melt compounding methods include: co-rotating and counter-rotating extruders, single screw extruders, disc-pack processors and various other types of extrusion equipment. In some instances, the compounded material exits the extruder through small exit holes in a die and the resulting strands of molten resin are cooled by passing the strands through a water bath. The cooled strands can be chopped into pellets for packaging and further handling, including grinding. Commercial grinding equipment is known in the art and often involves revolving blades to reduce the particle size to the desired dimensions.

The process of compounding can improve the mechanical, physical, thermal, optical, and/or functional properties of the compounded polymer. In some instances the cost of the compounded polymer can be reduced per unit weight as compared with raw feed polymer(s).

The selection of the type and amount of the polystyrene to be included in the compounding step is well within the skill of a person of skill in the art and will generally depend on the desired mechanical, physical, thermal, and/or functional properties of the polymer composition. In certain embodiments, the polystyrene has an average molecular weight of about 50,000 amu to about 400,000 amu; about 50,000 amu to about 350,000 amu; about 50,000 amu to about 300,000 amu; about 50,000 amu to about 250,000 amu; about 70,000 amu to about 250,000 amu; about 90,000 amu to about 250,000 amu; about 90,000 amu to about 250,000 amu; about 90,000 amu to about 230,000 amu; about 90,000 amu to about 210,000 amu; about 1 10,000 amu to about 210,000 amu; or about 120,000 amu to about 200,000 amu. In certain embodiments, the polystyrene has an average molecular weight of about 120,000 amu to about 200,000 amu. In certain embodiments, the polystyrene is a high impact polystyrene.

The high impact polystyrene which can be included in the polymer compositions according to the present disclosure comprises a combination of a polystyrene homopolymer and/or copolymer and an impact modifier. Specifically, the polystyrene homopolymer and/or copolymer comprises polymer units derived from a styrene monomer having the following formula:

wherein Ri and R₂ are selected from the group consisting of lower alkyl or alkenyl groups of from, for example, 1 to 6 carbon atoms and hydrogen, each R is selected from the group consisting of halogen, hydrogen and lower alkyl groups of from, for example, 1 to 6 carbon atoms, and n is an integer of from 0 to 5. Throughout the specification and claims the term "polystyrene homopolymer or copolymer" includes unsubstituted polystyrene homopolymer, substituted polystyrene homopolymers and substituted and unsubstituted polystyrene copolymers. For example, suitable polystyrenes include, but are not limited to, homopolymers of polystyrene, polychlorostyrene, polymethylstyrene and the like, and styrene-containing copolymers such as styrene-acrylonitrile copolymers, copolymers of ethyl vinyl benzene and divinyl benzene, styrene-acrylonitrile-methylstyrene terpolymers and the like. The methods for preparing these polystyrenes are well known in the art. The polystyrene homopolymer or copolymer which is included in the high impact polystyrene generally has a weight average molecular weight of about 250,000 amu or less. The impact modifier included in the high impact polystyrene resins according to the present disclosure serves to improve the impact properties of the resulting blends. Impact modifiers are well known in the art and generally comprise rubber or elastomer compounds. Both natural and synthetic rubber and elastomeric compounds are suitable for use in the high impact polystyrene. In certain embodiments, the impact modifiers include homopolymers or copolymers of one or more monomers such as butadiene, isoprene and ethylene-propylene diene monomers. Suitable impact modifiers include, but are not limited to, hydroxy- and carboxy-terminated polybutadienes, poly-chlorobutadienes, copolymers of dienes such as butadiene and isoprene with various comonomers such as alkyl unsaturated esters, for example methylmethacrylate, unsaturated ketones, for example methylisopropenyl ketone, vinyl heterocyclics, for example vinyl pyridine, and the like. Other impact modifiers known in the art may also be used according to the present disclosure.

In certain embodiments, the impact modifier and the polystyrene homopolymer or copolymer which are combined to form the high impact polystyrene included in the polymer compositions described herein are combined prior to mixing with the other composition ingredients. Additionally, the polystyrene homopolymer or copolymer and the impact modifier can be combined in a ratio of at least about 1 :1 or 3: 1, by weight to form the high impact polystyrene which is then blended with the powdered graft natural rubber and any additives.

In certain embodiments, the impact modifier in the high impact polystyrene is polybutadiene and is present in amount between about 1% and about 10% w/w; about 2% and about 10% w/w; about 3% and about 10% w/w; about 4% and about 10% w/w; about 4% and about 9% w/w; or about 5% and about 8% w/w; and the polystyrene is present between about 90% and 99% (w/w); about 90% and 98% (w/w); about 90% and 97% (w/w); about 90% and 96% (w/w); about 91% and 96% (w/w); about 92% and 96% (w/w); or about 92% and 95% (w/w). In certain embodiments, the impact modifier in the high impact polystyrene is polybutadiene and is present in an amount between about 5% and 8% (w/w) and the polystyrene is present in an amount between about 92% and 95% (w/w).

Between about 5 to about 70 parts by weight of the powdered graft natural rubber can be compounded together with between about 30 to about 95 parts by weight of the polystyrene. In certain embodiments, between about 10 to about 70; about 10 to about 65; about 10 to about 60; about 10 to about 55; about 10 to about 50; about 15 to about 50; about 15 to about 45; about 20 to about 45; or about 20 to about 40; parts by weight of the powdered graft natural rubber can be compounded together with between about 30 to about 90; about 35 to about 90; about 40 to about 90; about 45 to about 90; about 50 to about 90; about 50 to about 85; about 55 to about 85; about 60 to about 85; about 60 to about 80 parts by weight of the polystyrene.

One or more additives can be included in the compounding step, which can improve the mechanical, physical, thermal, optical, and/or functional properties of the compounded polymer. Such additives can include compatibilizers, antioxidants, flame retardants, drip retardants, crystallization nucleators, dyes, pigments, colorants, reinforcing agents, fillers, stabilizers, processing aids, and antistatic agents. These additives are known in the art, as are their effective levels and methods of incorporation.

In certain embodiments, the additive is a lubricant. Exemplary lubricants include, but are not limited, to hydrocarbon waxes, petroleum oils, silicone oils, vegetable oils, metal stearates, stearates, alkyl amides, and combinations thereof.

In certain embodiments, the lubricant is calcium stearate, silicone oil, ethylene bis(stearamide), or combinations thereof.

The lubricant can be present in about 0.01 to about 5 parts by weight for each 100 parts by weight of powdered graft natural rubber and polystyrene used in the compounding step. In instances in which calcium stearate is the lubricant, about 0.01 to about 1 parts by weight of the calcium stearate per 100 parts by weight of the powdered graft natural rubber and polystyrene is used in the compounding step. In certain embodiments, about 0.01 to about 1 ; about 0.01 to about 0.9; about 0.01 to about 0.8; about 0.01 to about 0.7; about 0.01 to about 0.6; about 0.1 to about 0.6; or about 0.1 to about 0.5 parts by weight of the calcium stearate per 100 parts by weight of the powdered graft natural rubber and polystyrene is used in the compounding step. In instances in which a silicone oil is the lubricant, about 0.01 to about 0.5 parts by weight of the silicone oil per 100 parts by weight of the powdered graft natural rubber and polystyrene is used in the compounding step. In certain embodiments, about 0.01 to about 0.5; about 0.01 to about 0.4; about 0.01 to about 0.3; about 0.01 to about 0.2; or about 0.05 to about 0.2 parts by weight of the silicone oil per 100 parts by weight of the powdered graft natural rubber and polystyrene is used in the compounding step.

In instances in which ethylene bis(stearamide) is the lubricant, about 0.1 to about 5.0 parts by weight of the ethylene bis(stearamide) per 100 parts by weight of the powdered graft natural rubber and polystyrene is used in the compounding step. In certain embodiments, about 0.01 to about 4.5; about 0.01 to about 4.0; about 0.01 to about 3.5; about 0.01 to about 3.0; about 0.01 to about 2.5; about 0.1 to about 2.5; about 0.5 to about 2.5; or about 0.5 to about 2.0 parts by weight of the ethylene bis(stearamide) per 100 parts by weight of the powdered graft natural rubber and polystyrene is used in the compounding step.

In the examples below, the powdered graft natural rubber, polystyrene, and additives are compounded using a twin screw extruder according to the parameters shown in Table 3.

Table 3.

The polymer composition of Example 1 is prepared by compounding 20 parts by weight of the powdered graft natural rubber, 80 parts by weight of polystyrene, and between 0.05 and 2 parts by weight of ethylene bis(stearamide) in a twin screw extruder according to the parameters presented in Table 3.

The polymer composition of Example 2 is prepared by compounding 30 parts by weight of the powdered graft natural rubber, 70 parts by weight of polystyrene, and between 0.1 and 0.5 parts by weight of calcium stearate in a twin screw extruder according to the parameters presented in Table 3.

The polymer composition of Example 3 is prepared by compounding 40 parts by weight of the powdered graft natural rubber, 60 parts by weight of polystyrene, and between 0.05 and 0.2 parts by weight of silicone oil in a twin screw extruder according to the parameters presented in Table 3.

The physical properties of the polymer compositions prepared according to the process described herein can vary depending on the amount of each monomer component, polymer component, and additives used to prepare the polymer composition. The selection of which is well within the skill of a person of skill in the art. In certain embodiments, the polymer compositions prepared according to the process described herein have a melt flow index (MFI) of between about 1 and about 3.5 g/ 10 min; about 1.0 and about 2.0 g/10 min; or about 2.0 and about 3.0 g/10 min.

In certain embodiments, the polymer compositions prepared according to the process described herein have an Izod notched impact (NI) of between about 25 and about 55 Kg cm/cm²; about 25 and about 45 Kg cm/cm²; about 30 and about 50 Kg cm/cm²; or about 40 and about 55 Kg cm/cm².

In certain embodiments, the polymer compositions prepared according to the process described herein have a tensile strength of between about 180 and about 200 Kg/cm²; about 180 and about 190 Kg/cm²; or about 190 and about 200 Kg/cm². In certain embodiments, the polymer compositions prepared according to the process described herein have a gloss of between about 70 to about 95 GU; 80 to about 95 GU; or about 85 to about 95 GU. In certain embodiments, the polymer compositions prepared according to the process described herein have an elongation at break of between about 30% to about 50%; about 30% to about 40%; or about 40% to about 50%.

In certain embodiments, the polymer compositions prepared according to the process described herein have a flexural modulus of between about 1.2 and about 2 X10⁴Kg/cm²; about 1.4 and about 1.6 X10⁴ g/cm²; or about 1.6 and about 2.0 Kg/cm².

In certain embodiments, the polymer compositions prepared according to the process described herein have a Vicat softening temperature of about 95° C to about 100° C.

In certain embodiments, the polymer compositions prepared according to the process described herein have a heat deflection temperature of about 74° C to about 78° C. In certain embodiments, the polymer compositions prepared according to the process described herein have a yellowness index (YI) of about 20 to about 35 or about 25 to about 30.

The example provided below serves to enhance clarity and/or appreciation for particular embodiments of the present disclosure. It will be understood that the scope of the present disclosure is not limited in any way by the example described below. The example provided is solely for aiding or enabling the reader to have a better understanding and/or appreciation of particular embodiments of the present disclosure. EXAMPLES

Chemical vulcanization employing the components as shown in Table 1

Table 1.

The vulcanization of natural rubber (NR) is conducted in a 20 litre reactor. Reagent solutions used in the vulcanization reaction are first prepared, such as the catalyst solution, antioxidant solution, and emulsifier solution. Once the reagent solutions have been prepared, the natural rubber (NR), antioxidant solution, and crosslinking agent (DVB) are added into the reactor and the temperature in the reactor is increased to 70 degrees Celsius. Once the temperature is constant, the catalyst solution and emulsifier solution are added continuously (continuous charge) over a period of one hour. The reaction is then allowed to react at 70 degrees Celsius for 7 hours.

PVNR Latex Properties

Properties Unit PVNR-001 PVNR-002

TSC % 41.47 41.10

SOL (Soluble) % 15.63 15.86

Gel-(Insoluble) % 84.37 84.14

Deg. Swelling gel - 0.13 0.13 Step 2 : Graft Polymerization employing the components as shown in table 2

Table 2.

The graft polymerization is conducted in a 20 litre reactor by bringing the natural rubber (NR) that was vulcanized in the vulcanization process, having a gel content in the range of 90-95%, together with the ammonium hydroxide solution in the reactor. The temperature is then increased to 68 degrees Celsius in the reactor. Once the temperature is constant, styrene monomer (20% of the total to be used) is added into the reactor, followed by the catalyst solution, and the components are allowed to react for 30 minutes at 68 degrees Celsius. The remainder of the styrene monomer and emulsifier are continuously (continuous charge) added to the reactor over a period of 6 hours. After which, the temperature in the reactor is maintained at 68 degrees Celsius for 30 minutes. The temperature in the reactor is then increased to 75 degree Celsius and maintained at this temperature for 3 hours in order to complete the reaction.

NR-g-ST Latex Properties

Properties Unit

001 002 pH - 10.06 10.06

TSC % 42.34 42.27

TB - 7.52 7.52

Density g/cm3 0.987 0.987

Graft ratio % 59.98 59.76

IV of free PS - 0.08 0.07

Coagulum % 0.02 0.02

R-monomer % 0.26 0.37

Rubber content %

PVNR (% NR) 50 50 Step 3 : Flocculation of the Grafted Natural Rubber employing the components as shown in Table 3

Table 3.

The latex master batch is first prepared by mixing latex comprising natural rubber (NR), the metal deactivator to aid in sequestering metal from the system, the colour stabilizer, and the antioxidant. The prepared mixture is referred to as the latex master batch. The flocculation is conducted in a 15 litre flocculation tank by adding water into reactor (12 litres), and then adding the coagulant aid. The temperature is then increased in the flocculation tank to between 80-85 degrees Celsius. Once the temperature is constant, the latex master batch is slowly added into the tank. The flocculation reaction begins gradually. The temperature is maintained at 85 degree Celsius for 15-30 minutes, during which time colloids separate from the water and are collected by filtration. The wet powders (separated colloids) are then dried in an oven at a temperature of 80 degree Celsius for 24 hours (drying process). The product from this process is referred to as polymer granule NR-g-ST (Green HIPS powder), which comprises natural rubber (NR) in the composition.

Step 4 : Compounding process , which formula and composition are shown in table 4

The compounding process is presented by mixing chemicals which have the following exemplary compositions: 1. Polymer granule NR-g-ST(Green HIPS POWDER) which comprises natural rubber (NR) 20-40 part by weight, and HIPS granule 60-80 part by weight, and additive type 1 (Additive 1) 0.5-2.0 part by weight, and additive type 2 (Additive 2) 0.1-0.5 part by weight, and additive type 3 (Additive 3) 0.05-0.2 part by weight, and/or mixture thereof.

2. Mixing all chemicals by using twin screw extruder, controlling temperature and appropriate speeds and be granulated by using plastic granulator.

Green HIPS (compound Recipe) Compositions

1 2 3

Resin

Part Part Part

NR-g-ST (50%) 20 30 40

HIPS HI650 80 70 60

Additive Yes Yes Yes

% NR 10 15 20

Compounding conditions of twin screw extruder

HIPS Properties RESULT

Example 1

Properties Unit 1 2 AV.

MFI g/10 min 3.04 3.04 3.04

NI Kg.cm/cm2 27.3 29.7 28.5

Tensile strength Kg/cm2% 199 202 200.5

Elongation % 46 40 43

Flexural strength Kg/cm2 378 380 379

Flexural modulus Kg/cm2xl04 1.9 1.9 1.9 Gloss GU 90 96 93

VST Degree C 97.2 97.1 97.15

HDT(non) Degree C 76 77.4 76.7

YI - 30.5 31.2 30.85

Colour differential

L - 76.7 76.1 76.4

A - 3.1 3.4 3.25

B - 14.9 15.1 15

Example 2.

Properties Unit 1 2 AV.

MFI g/10 min 1.82 1.84 1.83

NI Kg.cm/cm2 44.6 45.5 45.05

Tensile strength Kg/cm2% 195 196 195.5

Elongation % 43 42 42.5

Flexural strength Kg/cm2 366 369 367.5

Flexural modulus Kg/cm2xl04 1.6 1.6 1.6

Gloss GU 88 88 88

VST Degree C 97.5 97.6 97.55

HDT(non) Degree C 75.8 76.2 76

YI - 24.6 27.4 26

Colour differential

L - 80.1 78.8 79.45

A - 1.5 2.4 1.95

B - 12.9 13.8 13.35

Example 3.

Properties Unit 1 2 AV.

MFI g/10 min 1.12 1.18 1.15

NI Kg.cm/cm2 51.0 53.6 52.3

Tensile strength Kg/cm2% 185 183 184

Elongation % 40 34 37

Flexural strength Kg/cm2 340 328 334

Flexural modulus Kg/cm2xl04 1.4 1.4 1.4

Gloss GU 92 74 83

VST Degree C 98.0 97.7 97.85

HDT(non) Degree C 74.7 74.6 74.65

YI - 27.1 24.5 25.8 Color differential

L - 79.0 80.2 79.6

A - 2.3 1.5 1.9

B - 13.7 12.9 13.3

Claims

1. A process for preparing a polymer composition comprising:

contacting about 40 to about 70 parts by weight of a cross-linked natural rubber with about 30 to about 60 parts by weight of styrene thereby forming a graft natural rubber; and

compounding about 5 to about 70 parts by weight of the graft natural rubber with about 30 to about 95 parts by weight of a polystyrene thereby forming the polymer composition.

2. The process of claim 1, further comprising contacting a natural rubber with a divinyl benzene thereby forming the cross-linked natural rubber.

3. The process of claim 2, wherein about 100 parts by weight of the natural rubber is contacted with about 0.1 to about 1 parts by weight of the divinyl benzene.

4. The process of claim 1, wherein the cross-linked natural rubber has a total solids content of between about 30% and about 50% by weight and a gel fraction between about 80% and about 90%.

5. The process of claim 1, wherein contacting the cross-linked natural rubber and the styrene comprises adding the styrene to the cross-linked natural rubber at a temperature of at least about 50° C.

6. The process of claim 5, wherein the styrene is added to the cross-linked natural rubber over the course of at least about 4 hours at a temperature between about 50° C and about 70° C and then maintaining the temperature at between about 72° C and about 80° C for at least about 30 minutes.

7. The process of claim 1, wherein about 40 to about 60 parts by weight of the cross-linked natural rubber is contacted with about 40 to about 60 parts by weight of the high impact polystyrene.

8. The process of claim 1, further comprising flocculating the graft natural rubber at a temperature between about 70° C and about 90° C thereby forming a powdered graft natural rubber.

9. The process of claim 8, wherein flocculating the graft natural rubber comprises contacting the graft natural rubber with magnesium sulfate.

10. The process of claim 8, wherein between about 20 and about 40 parts by weight of the powdered graft natural rubber is compounded with about 60 to about 80 parts by weight of a polystyrene.

1 1. The process of claim 10, wherein compounding further comprises between about 0.01 to about 3 parts by weight of a lubricant.

12. The process of claim 11, wherein the lubricant is calcium stearate, silicone oil, or ethylene bis(stearamide).

13. The process of any one of claims 1-12, wherein the polystyrene is a high impact polystyrene.

14. A process for preparing a polymer composition comprising:

contacting 100 parts by weight of a natural rubber with about 0.1 to about 1 parts by weight of a divinyl benzene thereby forming a cross-linked natural rubber, wherein the cross-linked natural rubber has a total solids content of between about 30% and about 50% by weight and a gel fraction between about 80% and about 90%;

adding about 30 to about 60 parts by weight of styrene to about 40 to about 70 parts by weight of the vulcanized natural rubber at a temperature of at a temperature between about 50° C and about 70° C and then maintaining the temperature at between about 72° C and about 80° C for at least two hours thereby forming a graft natural rubber;

contacting the graft natural rubber with magnesium sulfate at a temperature between about 70° C and about 90° C thereby forming a powdered graft natural rubber; and

compounding between about 20 and about 40 parts by weight of the powdered graft natural rubber with about 60 to about 80 parts by weight of a high impact polystyrene thereby forming a polymer composition.

15. A polymer composition comprising about 5 to about 70 parts by weight of a graft natural rubber and about 30 to about 95 parts by weight of a polystyrene, wherein the graft natural rubber comprises about 30 to about 60 parts by weight of styrene and about 40 to about 70 parts by weight of a cross-linked natural rubber.

16. The polymer composition of claim 15, wherein the polystyrene is a high impact polystyrene.

17. The polymer composition of claim 15, wherein the cross-linked natural rubber comprises about 100 parts by weight of a natural rubber and about 0.1 to about 1 parts by weight of a divinyl benzene.

18. The polymer composition of claim 15, wherein the graft natural rubber comprises about 45 to about 55 parts by weight of styrene and about 45 to about 55 parts by weight of a cross-linked natural rubber.

19. The polymer composition of claims 15 or 17 comprising about 20 to about 40 parts by weight of a graft natural rubber and about 60 to about 80 parts by weight of a high impact polystyrene.

20. The polymer composition of claim 15 further comprising a lubricant.

21. The polymer composition of claim 15, wherein the polymer composition exhibits an Izod notched impact of between about 25 and about 55 Kg cm/cm².

22. The polymer composition of claim 15, wherein the polymer composition exhibits a tensile strength of between about 180 and about 200 Kg/cm².

23. The polymer composition of claim 15, wherein the polymer composition exhibits a gloss of about 70 to about 95 GU measured according to ASTM D523.

24. A polymer composition comprising about 20 to about 40 parts by weight of a graft natural rubber and about 60 to about 80 parts by weight of a high impact polystyrene, wherein the graft natural rubber comprises about 50 parts by weight of styrene and about 50 parts by weight of a cross-linked natural rubber, wherein the cross-linked natural rubber comprises about 1 part by weight of divinyl benzene and 00 parts by weight of a natural rubber and the polymer composition exhibits an Izod notched impact of between about 25 and about 55 Kg cm/cm² and a gloss of about 70 to about 95 GU.