Technical Field

The present disclosure relates generally to a method for producing, manufacturing, or preparing a styrene acrylonitrile resin. More particularly, the present disclosure relates to a method for producing, manufacturing, or preparing a styrene acrylonitrile resin that has excellent transparency properties, enhanced clarity, reduced hue, very low haze, and/or better physical appearance as a result of a polymerization reaction that occurs in the presence of an appropriate quantity of 1,1- Di(tert-butylperoxy)cyclohexane.

Background

Styrene acrylonitrile resin, commonly known as SAN resin or SAN, is a transparent copolymer thermoplastic. SAN is widely used in the applications of food containers, kitchenware, computer products, packaging materials such as cosmetic containers, battery cases, plastic optical fibers, and electronics appliances. In addition, SAN is often used in replace of polystyrene due to its greater thermal resistance. SAN resin can be further used to produce or manufacture acrylonitrile butadiene styrene (ABS), which possesses high chemical resistance, strength, toughness, and rigidity.

SAN is produced, manufactured, or prepared by co-polymerizing styrene and acrylonitrile monomers. Presently, there are several manufacturing methods or processes for producing SAN resin in an industrial scale; for instance, an emulsion polymerization, a suspension polymerization, or a continuous bulk polymerization. The continuous bulk polymerization methods or processes are often used due to advantages in view of minimum or less impurities obtained and less energy consumption or cost. During the course of polymerization of styrene and acrylonitrile monomers, monomers are heated to reach a certain high or relatively high temperature in order to generate free radicals, thereby thermally initiating polymerization reaction. The reaction temperature must be maintained sufficiently high in order not to compromise overall production process of polymerization. However, in said process conditions or states, more particularly at a high reaction temperature required for thermal initiation of polymerization, the production or manufacturing process will give rise to undesirable, unacceptable, and/or unavoidable yellow tint or reduced transparency SAN resin products. This phenomenon is even more pronounced when manufacturing SAN resin at high acrylonitrile content to achieve SAN resin having higher or more durable mechanical properties because of the high reaction temperature required. In such circumstances, the entire SAN resin manufacturing process has to be stopped to wash out unwanted SAN resin, and restarted to produce and obtain SAN resin with acceptable transparency. Such process interruption results in undesirably decreased process efficiency, longer required production time, and increased production cost.

Accordingly, there exists a need for a method, process, or technique for preparing, producing, or manufacturing SAN resin with a better, improved, enhanced, or excellent transparency without compromising overall process efficiency. More particularly, there is an urgent need for a method, process, or technique for preparing, producing, or manufacturing SAN resin at a lower temperature to reduce unwanted yellow tint SAN resin that results from high reaction temperature. Moreover, an improved method, process or technique for preparing, producing, of manufacturing SAN resin with shorter process or production time, and/or higher process output is required. Summary

In accordance with an aspect of the disclosure, a process for producing a styrene acrylonitrile (SAN) resin having enhanced transparency includes exposing an amount (e.g., mass or weight) of styrene monomers and acrylonitrile monomers under consideration to l,l-Di(tert- butylperoxy)cyclohexane, the l,l-Di(tert-butylperoxy)cyclohexane having a concentration between approximately 5 - 500 parts per million (ppm) relative to the amount of the styrene monomers and acrylonitrile monomers under consideration; initiating polymerization reactions involving the styrene monomers and the acrylonitrile monomers exposed to the l,l-Di(tert- butylperoxy)cyclohexane; continuing, maintaining, or sustaining the polymerization reactions for a polymerization time period; stopping the polymerization reactions; and obtaining a SAN resin having a haze value significantly less than approximately 0.50. Depending upon embodiment details, the SAN resin can have a haze value that is less than or equal to approximately 0.45, 0.40, 0.35, 0.30, 0.25, 0.20, 0.15, or 0.10.

The process can additionally include exposing the styrene monomers and the acrylonitrile monomers to a solvent; exposing the styrene monomers and the acrylonitrile monomers to a chain transfer agent; and uniformly blending the styrene monomers and the acrylonitrile monomers with each of the solvent, the chain transfer agent, and the l,l-Di(tert-butylperoxy)cyclohexane. Initiating the polymerization reactions can include exposing the styrene monomers and the acrylonitrile monomers to a temperature between approximately 85 - 130 °C (e.g., approximately 90, 100, 1 10, 1 15, 120, or 125 °C) to facilitate or enable the initiation or polymerization in the presence of l,l-Di(tert-butylperoxy)cyclohexane. Continuing, maintaining, or sustaining the polymerization reactions can include exposing the styrene monomers and the acrylonitrile monomers to a temperature between approximately 85 - 130 °C for a polymerization time interval of approximately 0.5 - 3.5 hours (e.g., a time interval of approximately 1.0 - 3.0 hours) to facilitate or enable polymerization to continue in the presence of l,l-Di(tert- butylperoxy)cyclohexane.

In some embodiments, exposing the styrene monomers and the acrylonitrile monomers to 1,1- Di(tert-butylperoxy)cyclohexane occurs in the absence of exposure of the styrene monomers and the acrylonitrile monomers to a polymerization initiator that is other than l,l-Di(tert- butylperoxy)cyclohexane. Other embodiments include exposing the styrene monomers and the acrylonitrile monomers to a polymerization initiator that is other than l,l-Di(tert- butylperoxy)cyclohexane, wherein the concentration of l,l-Di(tert-butylperoxy)cyclohexane is at least approximately 80% greater (e.g., approximately 90%, 95%, or 98% greater) than the concentration of the polymerization initiator that is other than l,l-Di(tert- butylperoxy)cyclohexane.

Particular material or chemical properties other than transparency or haze of an enhanced transparency SAN resin produced in accordance with an embodiment of the present disclosure can be substantially identical to corresponding properties of SAN resin produced in the absence of l, l-Di(tert- butylperoxy)cyclohexane. For instance, an enhanced transparency SAN resin produced in accordance with an embodiment of the disclosure can have a melt flow index (MFI) and an internal viscosity (IV) which are substantially identical to an MFI and an IV for a low transparency SAN resin produced in the absence of l,l-Di(tert-butylperoxy)cyclohexane.

In accordance with another aspect of the disclosure, a computer based process that is executed on a computer and which is directed to producing or manufacturing a styrene acrylonitrile (SAN) resin having enhanced transparency from styrene monomers and acrylonitrile monomers includes determining a set of process parameters for producing the SAN resin by way of receiving a target haze value in response to user input directed to the computer system; determining an amount of styrene monomers and acrylonitrile monomers under consideration; and automatically determining a l,l-Di(tert-butylperoxy)cyclohexane concentration appropriate for producing a SAN resin having the target haze value with respect to the amount of styrene monomers and acrylonitrile monomers under consideration. Determining the set of process parameters can further include receiving at least one of a target polymerization reaction temperature and a target polymerization time period in response to user input directed to the computer system; and/or determining an actual or required polymerization time period that is expected to correspond to a target minimum polymer conversion percentage. The process further includes producing a SAN resin having the target haze value, where such production of the SAN resin includes combining the amount of styrene monomers and acrylonitrile monomers under consideration with the determined concentration of a l,l-Di(tert- butylperoxy)cyclohexane. The determined l,l-Di(tert-butylperoxy) cyclohexane concentration can be between approximately 5 - 500 ppm, and the target haze value is significantly less then approximately 0.5 (e.g., the target haze value can be less than or equal to approximately 0.45, 0.40, 0.35, 0.30, 0.25, 0.20, 0.15, or 0.10).

Brief Description of the Drawings

FIG. 1 is a flowchart of a process for preparing, manufacturing, or producing an enhanced or high transparency / reduced or low haze styrene acrylonitrile (SAN) resin using l,l-Di(tert- butylperoxy)cyclohexane as a sacrificial agent according to an embodiment of the disclosure.

FIG. 2A is a representative graph that illustrates a relationship between percentage conversion realized for a 2 hour polymerization time period versus ppm of l,l-Di(tert- butylperoxy)cyclohexane relative to a total weight of styrene monomers and acrylonitrile monomers mixed or blended with or exposed to l,l-Di(tert-butylperoxy)cyclohexane.

FIG. 2B is another representative graph that illustrates a relationship between percentage conversion realized for a 3 hour polymierization time period versus ppm of l,l-Di(tert- butylperoxy)cyclohexane relative to a total weight of styrene monomers and acrylonitrile monomers mixed or blended with or exposed to l,l-Di(tert-butylperoxy)cyclohexane.

FIG. 3 is a representative graph corresponding that illustrates a relationship between between measured SAN resin haze values versus ppm of Di(tert-butylperoxy)cyclohexane relative to a total weight of styrene monomers and acrylonitrile monomers that were mixed or blended with or exposed to l,l-Di(tert-butylperoxy)cyclohexane.

FIG. 4 is a flow diagram of a process for producing an enhanced or high transparency / reduced or low haze SAN resin or composition using l,l-Di(tert-butylperoxy)cyclohexane as a sacrificial agent according to another embodiment of the disclosure.

Detailed Description

Embodiments of the present disclosure are directed to aspects of processes for producing styrene acrylonitrile (SAN) resin having excellent, high, very high, or essentially maximal transparency, or equivalently, reduced, low, very low, or essentially minimal haze values. Processes in accordance with the present disclosure involve exposing styrene and acrylonitrile monomers to an appropriate assistive or sacrificial agent or quasi-catalyst that significantly reduces the temperature at which polymerization occurs, significantly increases a polymerization reaction rate, and significantly increases the extent of monomer to polymer conversion. Embodiments of the present disclosure are additionally directed to SAN resin produced by such processes, where the SAN resin is characterized by low or very low haze values, for instance, haze values less than or significantly less than approximately 0.50, for instance, haze values less than approximately 0.50 and greater than or equal to approximately 0.10 (e.g., haze values between approximately 0.18 - 0.48, or a haze value less than or equal to approximately 0.45, 0.40, 0.35, 0.30, 0.25, 0.20, 0.15, or 0.10).

In various embodiments, an assistive or sacrificial agent or quasi-catalyst includes or is a particular organic peroxide, namely, l,l-Di(tert-butylperoxy)cyclohexane, which for purpose of brevity and clarity is referred to hereafter as a sacrificial agent. The concentration of l,l-Di(tert- butylperoxy)cyclohexane can be established, varied, adjusted, or tailored to produce SAN resins having target or intended haze values, as further described in detail below.

While other organic peroxides such as Benzoyl peroxide [C6H ₅ C(0)] ₂ 0 ₂ , Di-tert-butyl perioxide (CH ₃ ) ₃ COOC(CH ₃ ) ₃ , and Tert-butylperoxy isopropyl carbonate C ₈ Hi ₆ 0 ₄ are known to increase polymerization reaction rate, such other organic peroxides fail to facilitate or effectuate the production of SAN resins having significantly enhanced, high, very high, or maximal transparency (or significantly reduced, low, very low, or minimal haze values). Such other organic peroxides can additionally fail to facilitate or effectuate the production of SAN resins having other desirable properties, such as a high intrinsic viscosity.

In the context of the present disclosure, the term "set" set is defined as a non-empty finite organization of elements that mathematically exhibits a cardinality of at least 1 (i.e., a set as defined herein can correspond to a singlet or single element set, or a multiple element set), in accordance with known mathematical definitions (for instance, in a manner corresponding to that described in An Introduction to Mathematical Reasoning: Numbers, Sets, and Functions, "Chapter 1 1 : Properties of Finite Sets" (e.g., as indicated on p. 140), by Peter J. Eccles, Cambridge University Press (1998)).

Aspects of a Representative Manufacturing Process

FIG. 1 is a flow diagram of a process 100 for producing a high transparency / low haze SAN resin or composition using l,l-Di(tert-butylperoxy)cyclohexane as a sacrificial agent according to an embodiment of the disclosure. In an embodiment, the process 100 includes a first process portion 110 involving combining (e.g., blending or mixing) given (e.g., predetermined) quantities of styrene monomer, acrylonitrile monomer, and an appropriate solvent in a polymerization reaction vessel or chamber having a volume suitable for carrying a given (e.g., predetermined) mass of chemical constituents under consideration. In a representative embodiment, the vessel can be a stainless steel reactor having an internal volume of, for instance, approximately 5 or more (e.g., approximately 10, 20, 50, 100, 1000, or 2000) liters. The vessel can be maintained under an inert (e.g., Nitrogen) atmosphere at a desired pressure (e.g., approximately 1 bar) during one or more portions of the process 100, in a manner understood by one of ordinary skill in the art. Depending upon embodiment details, the solvent can include one or more of an alcohol, a ketone, an aromatic hydrocarbon, or other solvent. For instance, the solvent can include methanol, ethanol, methyl ethyl ketone (MEK), methyl isobutyl ketone, toluene, xylene, tetrahydrofuran, dimethylformamide (DMF), and/or another substance in which styrene monomer and acrylonitrile monomer are soluble. A second process portion 120 involves introducing a given (e.g., predetermined) amount of a chain transfer and/or molecular size controlling agent such as a mercaptan into the vessel, and blending or mixing vessel contents. In a representative embodiment, the chain transfer / molecular size controlling agent can include or be tertiary dodecyl mercaptan (TDM). One of ordinary skill in the art will understand that the second process portion 120 can involve another chain transfer / molecular size controlling agent (e.g., a different mercaptan) depending upon embodiment details.

A third process portion 130 involves introducing a given (e.g., predetermined) quantity of 1,1- Di(tert-butylperoxy)cyclohexane as a sacrificial agent into the vessel, and further blending or mixing vessel contents. Depending upon embodiment details, the amount of l,l-Di(tert- butylperoxy)cyclohexane introduced into the vessel can be between approximately 5 - 500 parts per million (ppm) with respect to a total mass or weight of styrene and acrylonitrile monomers within the vessel. For instance, in multiple embodiments, the amount of l,l-Di(tert- butylperoxy)cyclohexane introduced into the vessel can be between approximately 10 - 400 ppm (e.g., approximately 50 - 300 ppm, or approximately 100 - 200 ppm). In general, the quantity of l,l-Di(tert-butylperoxy)cyclohexane under consideration can be selected or determined based upon the total mass or weight of styrene and acrylonotrile monomers under consideration, in view of one or more of a desired, intended, or target (a) polymerization time; (b) polymerization temperature or temperature range; (c) polymerization conversion degree, level, measure, ratio or efficiency; and (d) SAN resin haze value, as further described in detail below.

In multiple embodiments, a process 100 in accordance with the present disclosure involves using l,l-Di(tert-butylperoxy)cyclohexane as a sacrificial agent in the absence or to the exclusion of another chemical substance, composition, or compound that can act as a polymerization initiator, catalyst, or sacrificial agent. However, in certain embodiments, l,l-Di(tert- butylperoxy)cyclohexane can be used a sacrificial agent for producing SAN resins having reduced, low, or very low haze values in accordance with the present disclosure, and one or more other chemical substances capable of acting as a polymerization initiator, catalyst, or sacrificial agent (e.g., in a manner that reduces polymerization temperature and/or enhances polymerization conversion) can be introduced into the reaction vessel (e.g., before, during, or after the third process portion 130). However, in embodiments in which the reaction vessel includes l,l-Di(tert- butylperoxy)cyclohexane as well as one or more other chemical substances capable of acting as a polymerization initiator, catalyst, or sacrificial agent, the quantity or concentration (e.g., weight percentage) of l,l-Di(tert-butylperoxy)cyclohexane should dominate or overwhelmingly dominate the quantity or concentration of such other chemical substance(s) in order to produce a SAN resin having a significantly reduced, low, very low, or essentially minimal haze value. For instance, the quantity or concentration of l,l-Di(tert-butylperoxy)cyclohexane should be greater than or equal to approximately 80%, 90%, 95%, or 98% of the quantity or concentration of such other chemical substance(s).

A fourth process portion 140 involves heating the vessel contents to a temperature sufficient to initiate polymerization reactions. In various embodiments, the fourth process portion 140 involves heating the vessel contents to a temperature between approximately 85 - 135 °C (e.g., approximately 90 - 130 °C, or approximately 90 - 120 °C, 100 - 1 15 °C, or approximately 1 10 °C). A fifth process portion 150 involves maintaining the vessel contents at a temperature or within a temperature range sufficient to sustain polymerization reactions, such as a set of temperatures within one or more of the aforementioned temperature ranges, for a given (e.g., predetermined) time interval that can be defined as a polymerization time period. Depending upon embodiment details, the polymerization time period can be approximately 1.0 to approximately 4.0 hours, for instance, approximately 1.5 - 3.5 hours (e.g., approximately 2.0, 2.5, or 3.0 hours). A sixth process portion 160 involves reducing the internal temperature of the vessel to stop further polymerization reactions. In various embodiments, the internal vessel temperature can be cooled to below approximately 80 °C, for instance, to below approximately 50 °C. Finally, a seventh process portion 170 involves collecting or recovering enhanced, high, or very high transparency SAN resin from the vessel.

Representative Examples

The following representative examples describe experiments showing effects, functions, characteristics and/or properties of particular SAN resins prepared or manufactured in accordance with embodiments of the present disclosure. It will be understood by a person of ordinary skill in the art that the scope of the present disclosure is not limited to the following representative examples.

COMPARATIVE EXAMPLE ONE

The experiments in comparative example one were performed to evaluate and determine a conversion of polymerization reaction of styrene monomer and acrylonitrile monomers in the absence and presence of l,l-Di(tert-butylperoxy)cyclohexane as a sacrificial agent at varying concentrations.

Preparation of SAN resins and analysis of styrene acrylonitrile (co)polvmer conversion A SAN resin according to an embodiment of the present disclosure was prepared and analyzed using the following process portions or process steps.

Process Step (i): Introducing monomers and reagent

Preparation was performed in a nitrogen atmosphere. Approximately 1 125 grams of styrene monomer, approximately 375 grams of acrylonitrile monomer, and approximately 150 grams of Ethyl benzene were introduced into a 5-liter reactor or reaction chamber. The pressure within the reactor was maintained at approximately 1 bar under nitrogen atmosphere. Ethyl benzene was used as a solvent and viscosity reducing medium for the reaction system. Styrene monomer, acrylonitrile monomer, and ethyl benzene were mixed for approximately 15 minutes to ensure uniformity. Following mixing, approximately 1.5 gram of tertiary dodecyl mercaptan (TDM) was added as a molecular size controlling agent or chain transfer agent. In addition, l,l-Di(tert- butylperoxy)cyclohexane was added as a sacrificial agent in varying amounts or concentrations, as detailed hereafter.

More particularly, in separate experiments, approximately 0.015 gram (equal to 10 ppm based on total weight of styrene and acrylonitrile monomers), approximately 0.030 gram (equal to 20 ppm), approximately 0.075 gram (equal to 50 ppm), and approximately 0.150 gram (equal to 100 ppm), or 0.210 gram (equal to 140 ppm) of l,l-Di(tert-butylperoxy)cyclohexane were added into the reactor, after which reactor contents were further mixed or agitated for approximately 15 minutes.

Process Step (ii): Polymerizing styrene and acrylonitrile monomers

In order to initiate a bulk polymerization reaction, the resulting mixture present in the reactor was heated using a heating rate of approximately 2 °C per minute up to a final temperature of approximately 140 °C for the experiment in the absence of l,l-Di(tert-butylperoxy)cyclohexane, or a final temperature of approximately 110 °C for the experiments in the presence of l,l-Di(tert- butylperoxy)cyclohexane. The temperature was accordingly maintained at approximately 140 °C or approximately 110 °C as a reaction temperature for a duration or polymerization time period of approximately 1, 2, 3 or 4 hours to allow the polymerization reaction to occur. The polymerization reaction was interrupted or stopped by subjecting or exposing the reactor vessel to liquid nitrogen for approximately 3 minutes.

Process Step (Hi): Analyzing percentage conversion of styrene and acrylonitrile polymerization Five grams of SAN samples obtained from the styrene and acrylonitrile polymerization reaction were collected and completely dissolved in approximately 100 milliliters of Methyl Ethyl Ketone (MEK). Subsequent complete dissolution, SAN samples were precipitated by introducing and stirring approximately 50 milliliters of methanol (MeOH) until SAN contents were entirely precipitated. Following the precipitation, SAN contents were filtered and dried at a temperature of approximately 80 °C for approximately 5 hours. SAN contents obtained were weighed, and percentage conversion was calculated.

Table 1 : Percentage conversion of styrene and acrylonitrile monomers in the absence and presence of 1 , 1 -Di(tert-butylperoxy)cyclohexane at different concentrations

Results and Discussion

Table 1 shows a percentage conversion of styrene and acrylonitrile monomers to form styrene acrylonitrile resin (SAN) (co)polymer in the absence and presence of l,l-Di(tert- butylperoxy)cyclohexane as a sacrificial agent at different concentrations. As shown in Table 1, considering or comparing results corresponding to any individual reaction time (i.e. an identical reaction time of approxiamtely 1 hour, 2, 3, or 4 hours), a percentage conversion to SAN polymer in the presence of l,l-Di(tert-butylperoxy)cyclohexane as a sacrificial agent at a reaction temperature of 110 °C was higher or significantly higher than in the absence of l,l-Di(tert- butylperoxy)cyclohexane at a reaction temperature of 140 °C. In other words, polymerization reaction of styrene and acrylonitrile monomers to form SAN resin could occur at significantly lower temperature (i.e. approximately 110 °C versus approximately 140 °C) in the presence of 1,1- Di(tert-butylperoxy)cyclohexane as a sacrificial agent. Lower reaction temperature is desirable in order to save energy and generate lower amounts of by-products associated with the polymerization reaction(s). Moreover, a percentage conversion to SAN polymer increased with increasing amount, quantity, or concentration of l,l-Di(tert-butylperoxy)cyclohexane at an identical reaction temperature of approximately 1 10 °C. For instance, at a reaction duration of approximately 3 hours, a percentage conversion to SAN polymer increased from approximately 35.1, 41.9, 46.8, 62.8, 66.8, to 71.3 when an amount or concentration of l,l-Di(tert- butylperoxy)cyclohexane increased from approximately 0, 10, 20, 50, 100, to 140 ppm. An increase of percentage conversion from approximately 35.1 to 71.3, or an approximately 100% or two-fold increase in conversion at an identical reaction time of approximately 3 hours, at a significantly reduced temperature of 1 10 °C rather than 140 °C, due to an activity of functionality of l,l-Di(tert-butylperoxy)cyclohexane is considered significant, unexpected, and/or surprisingly better relative to conventional SAN resin polymerization processes. Additionally, the use of 1,1- Di(tert-butylperoxy)cyclohexane as a sacrificial agent can facilitate or effectuate a decrease in the reaction time required to obtain target conversion, as compared to a polymerization reaction without l,l-Di(tert-butylperoxy)cyclohexane. For example, a conversion of approximately 50% required approximately 4 hours at a reaction temperature of approximately 140 °C in the absence of l,l-Di(tert-butylperoxy)cyclohexane. Comparatively, it required approximately only 2 hours at a reaction temperature of approximately 1 10 °C in the presenece of approximately 140 ppm of 1,1- Di(tert-butylperoxy)cyclohexane to achieve approximately 50% conversion. The significant reduction in reaction time required to obtain a target conversion, at a significantly reduced temperature (e.g., reduced by approximately 21.4% from a reference temperature of approximately 140 °C), is considered significant, unexpected, and/or surprisingly better.

FIG. 2A is a representative graph corresponding to the results shown in Table 1, which illustrates a relationship between percentage conversion realized for a 2 hour polymerization time period versus ppm of l,l-Di(tert-butylperoxy)cyclohexane (relative to the total weight of styrene monomers and acrylonitrile monomers that were mixed or blended with or exposed to l,l-Di(tert- butylperoxy)cyclohexane). FIG. 2B is another representative graph corresponding to the results shown in Table 1, which illustrates a relationship between percentage conversion realized for a 3 hour polymierization time period versus ppm of l,l-Di(tert-butylperoxy)cyclohexane (relative to the total weight of styrene monomers and acrylonitrile monomers that were mixed or blended with or exposed to l,l-Di(tert-butylperoxy)cyclohexane). As indicated in Table 1 and each of FIGs. 2A and 2B, polymer conversion is significantly enhanced even when a small concentration of 1,1- Di(tert-butylperoxy)cyclohexane (e.g., approximately, 5, 10, or 20 ppm) is considered, and very significantly or dramatically enhanced as l,l-Di(tert-butylperoxy)cyclohexane concentration further increases (e.g., to or beyond approximately 30, 40, 50, 80, 100, 120, 140, or more ppm). Conclusion

Results obtained from comparative example one suggest that a method, process, or technique for preparing or producing SAN resin according to multiple embodiments of the present disclosure can give rise to a significant or substantial increase in percentage conversion of styrene and acrylonitrile monomers at a significantly reduced reaction temperature to form SAN resin due to an activity, functionality or feature of a sacrificial agent, an assistive agent, and/or a quasi-catalyst provided by the present disclosure.

COMPARATIVE EXAMPLE TWO

Preparation of styrene acrylonitrile resins

A SAN resin according to an embodiment of the present disclosure was prepared using the following process portions or process steps.

Process Step (i): Introducing monomers and reagent

Preparation was performed in a nitrogen atmosphere. Approximately 1125 grams of styrene monomer, approximately 375 grams of acrylonitrile monomer, and approximately 150 grams of Ethyl benzene were introduced into a 5-liter reactor or reaction chamber. Ethyl benzene was used as a solvent and viscosity reducing medium for the reaction system. Styrene monomer, acrylonitrile monomer, and ethyl benzene were mixed for approximately 15 minutes to ensure uniformity. Following mixing, approximately 1.5 grams of tertiary dodecyl mercaptan (TDM) as a molecular size controlling agent or chain transfer agent was added, and reactor contents were further agitated for 15 minutes.

Process Step (ii) : Polymerizing styrene and acrylonitrile monomers

In order to initiate a bulk polymerization reaction, the resulting mixture present in the reactor was heated to approximately 150 °C and maintained at approximately 150 °C as a reaction temperature for a duration of approximately 3 hours. Following polymerization, the temperature was decreased to below approximately 50 °C to stop the polymerization reaction.

Process Step (in): Obtaining styrene and acrylonitrile resin

Unreacted monomers, excess reagents and solvents in liquid form were removed from styrene and acrylonitrile resins using an evaporator under a pressure of approximately 200 mmHg. Styrene and acrylonitrile resins were furthered cured at a temperature of approximately 70 °C for a duration of approximately 5 hours. The obtained polymer was subsequently crushed and processed to obtain testing specimens or samples.

Process Step (iv) .Specimen testing

Testing specimens or samples of SAN resin were prepared for testing purposes. More particularly, SAN specimens were tested for melt flow index (MFI), intrinsic viscosity (IV), and HAZE value. Melt Flow Index, also known as Melt Flow Rate or Melt Index, is a measure of the ease of flow of the melt polymer, with units of grams of polymer in ten minutes. MFI of SAN resin according to experiments in example one was measured according to ASTM D1238: Standard Test Method for Melt Flow Rates of Thermoplastics by Extrusion Plastometer p. 273- 286. Intrinsic viscosity (IV) of SAN resin was measured in accordance with an in-house protocol. Intrinsic viscosity is a dimensionless value. HAZE value, indicative of the transparency of SAN resin, was determined according to ASTM D1003: Standard Test Method for Haze and Luminous Transmittance of Transparent Plastics p. 205-210. Briefly, HAZE value is calculated as a percentage of a diffuse transmittance relative to a total transmittance obtained from a Hazemeter. A lower HAZE value corresponds to SAN resin having a higher transparency or better appearance.

The characteristics and properties of the SAN resin specimens corresponding to comparative example two are shown in Table 2 below.

EXAMPLE ONE

In example one, SAN resin was prepared or produced using analogous process portions as in comparative example two as provided above. However, in example one, the resulting mixture present in the reactor was heated to approximately 140 °C and maintained at approximately 140 °C as a reaction temperature in the process portion (ii) Polymerizing styrene and acrylonitrile monomers.

The characteristics and properties of the SAN resin specimens of example one are shown in Table 2 below.

EXAMPLE TWO

In example two, SAN resin was prepared or produced using analogous process portions as in comparative example two as provided above. However, in example two, approximately 0.075 grams of l,l-Di(tert-butylperoxy)cyclohexane as a sacrificial agent, and approximately 1.5 grams of tertiary dodecyl mercaptan (TDM) as a molecular size controlling agent or chain transfer agent were added into the reactor in the process portion (i) Introducing monomers and reagent. In other words, approximately 50 parts per million (ppm based on total weight of styrene and acrylonitrile monomers) of l,l-Di(tert- butylperoxy)cyclohexane as a sacrificial agent was additionally introduced into the reactor. Moreover, in example two, the resulting mixture present in the reactor was heated to approximately 130 °C and maintained at approximately 130 °C as a reaction temperature in the process portion (ii) Polymerizing styrene and acrylonitrile monomers.

The characteristics and properties of the SAN resin specimens of example two are shown in Table 2 below. EXAMPLE THREE

In example three, SAN resin was prepared or produced using analogous process portions as in example two as provided above.

However, with example three, approximately 0.150 grams of l,l-Di(tert-butylperoxy)cyclohexane as a sacrificial agent was added into the reactor in process portion (i) Introducing monomers and reagent. In other words, approximately 100 parts per million (ppm based on total weight of styrene and acrylonitrile monomers) of l,l-Di(tert-butylperoxy)cyclohexane as a sacrificial agent was additionally introduced into the reactor. The characteristics and properties of the SAN resin specimens of example three are shown in Table 2 below.

EXAMPLE FOUR

In example four, SAN resin was prepared or produced using analogous process portions as in example three as provided above.

However, with example four, approximately 0.210 grams of l,l-Di(tert-butylperoxy)cyclohexane as a sacrificial agent was added into the reactor in process portion (i) Introducing monomers and reagent. In other words, approximately 140 parts per million (ppm based on total weight of styrene and acrylonitrile monomers) of l, l-Di(tert-butylperoxy)cyclohexane as a sacrificial agent was additionally introduced into the reactor.

The characteristics and properties of the SAN resin specimens of example four are shown in Table 2 below.

Table 2: Characteristics and properties of the SAN resin specimens of comparative example two and example 1-4

Results and Discussion Based Upon Results Provided Above

Table 2 shows characteristics and properties of the SAN specimens obtained by process steps as described in comparative example two and examples 1-4. In particular, melt flow index (MFI), intrinsic viscosity (IV), and HAZE value (corresponding to % haze) of SAN specimens were tested. As shown in Table 2, MFI of SAN resins or specimens produced or prepared in the absence of l,l-Di(tert-butylperoxy)cyclohexane (i.e. comparative example two and example one) were approximately or generally similar to MFI values of SAN resins or specimens produced or prepared in the presence of l,l-Di(tert-butylperoxy)cyclohexane as a sacrificial agent (i.e. examples two to four). In addition, there was no or essentially no significant difference in MFI values with respect to an increased amount, quantity, or concentration of l,l-Di(tert- butylperoxy)cyclohexane used (i.e. an increase from 50, 100, to 140 ppm in examples two, three, and four, respectively). Intrinsic Viscosity values of SAN resins or specimens produced or prepared in an absence or presence of l,l-Di(tert-butylperoxy)cyclohexane as a sacrificial agent were approximately similar or relatively identical. As demonstrated in Table 2, the HAZE value of SAN resins or specimens produced in the absence of l,l-Di(tert-butylperoxy)cyclohexane at the reaction temperature of 150 °C (i.e. comparative example two) was approximately 0.68 (i.e., approximately 68%). The HAZE value of SAN resin decreased from approximately 0.68 to approximately 0.56 when the reaction temperature was decreased from approximately 150 °C (i.e. comparative example two) to approximately 140 °C (i.e, example one). This result indicated that reducing reaction temperature could decrease HAZE value or yield more transparent resins due to a lower or reduced amount of by-products associated with or generated from a polymerization reaction. The HAZE values of SAN resins or specimens produced in the presence of 1 , 1 -Di(tert-butylperoxy)cyclohexane at a concentration of approximately 50 (i.e, example two), approximately 100 (i.e, example three), and approximately 150 ppm (i.e, example four), at a reaction temperature of approximately 130 °C were approximately 0.48, 0.28, and 0.18, respectively. The results suggested that increasing l,l-Di(tert- butylperoxy)cyclohexane concentration could noticeably, significantly, or dramatically decrease HAZE values or yield more transparent, enhanced clarity SAN resins. Such significant improvement of HAZE values due to the presence of l,l-Di(tert-butylperoxy)cyclohexane as a sacrificial agent during the course of the polymerization reaction was an unexpected or surprising result. The presence of l,l-Di(tert-butylperoxy)cyclohexane led to a lower reaction temperature required (approximately 150 or 140 versus approximately 130 °C). The lower reaction temperature was desirable due to energy saving and reduced, lesser, or lower amounts of by-products generated or derived from the polymerization reaction that could cause haze or contribute to unwanted high HAZE values.

FIG. 3 is a representative graph corresponding to the results shown in Table 2, which illustrates a relationship between between SAN resin HAZE values realized versus ppm of Di(tert- butylperoxy)cyclohexane (relative to the total weight of styrene monomers and acrylonitrile monomers that were mixed or blended with or exposed to l,l-Di(tert-butylperoxy)cyclohexane). As indicated in Table 2 and FIG. 3, HAZE values are significantly reduced (or SAN resin transparency is significantly improved, enhanced, or increased) even when a small concentration of l,l-Di(tert-butylperoxy)cyclohexane (e.g., approximately, 5, 10, or 20 ppm) is considered, and HAZE values are very significantly or dramatically reduced (or SAN resin transparency is very significantly or dramatically improved, enhanced, or increased) as l,l-Di(tert- butylperoxy)cyclohexane concentration further increases (e.g., to or beyond approximately 30, 40, 50, 80, 100, 120, 140, or more ppm). Conclusion

Results obtained from comparative example two and corresponding individual examples one to four suggest that a method, process, or technique for preparing or producing styrene acrylonitrile resin (SAN) involving l,l-Di(tert-butylperoxy)cyclohexane as a sacrificial agent in accordance with various embodiments of the present disclosure can yield or achieve improved, enhanced, or excellent transparency of SAN resins without compromising other SAN resin physical properties or characteristics.

Additional Representative Manufacturing Process Considerations

In some embodiments, (a) a set of haze values, curves, or functions; and/or (b) a set of polymer conversion percentages or polymer conversion curves or functions relative to Di(tert- butylperoxy)cyclohexane concentration and one or more temperature values or temperature ranges can be generated, stored, retrieved, or accessed to aid the determination or selection of manufacturing process parameters that can result in the production of SAN resins having target, intended, or adjusted / tailored haze values. The production of a SAN resin having a target, intended, or tailored haze value can occur within or approximately within a target or desired (e.g. minimum) polymerization time period. One or more of the aforementioned values, curves, or functions can be generated, stored, retrieved, or accessed on or using an automated system, such as a computer or electronic system that is configured to automatically or semi-automatically manage one or more aspects of an enhanced transparency SAN resin manufacturing process in accordance with an embodiment of the disclosure.

FIG. 4 is a flow diagram of a process 200 for producing an enhanced or high transparency / reduced or low haze SAN resin or composition using l,l-Di(tert-butylperoxy)cyclohexane as a sacrificial agent according to another embodiment of the disclosure. A first process portion 210 involves retrieving (e.g., from a computer readable medium such as a memory) or receiving (e.g., as a result of user input, which can be received by way of user interaction with an input device such as a touch screen display, a computer mouse, or a keyboard) a target or desired haze or transparency value; and a second process portion 220 involves retrieving or receiving at least one of a target or desired polymerization reaction temperature and a target or desired polymerization time period. A third process portion 230 involves determining a l, l-Di(tert-butylperoxy)cyclohexane concentration (e.g., relative to an amount of styrene monomers and acrylonitrile monomers under consideration, such as a total mass or weight of such monomers) that is expected to result in the production of a SAN resin having the target or desired haze or transparency value. The third process portion 230 can involve accessing stored data and/or functions that estimate or establish one or more relationships between haze or transparency values and l, l-Di(tert-butylperoxy)cyclohexane concentration with respect to polymerization reaction temperature, and the selection of a l,l-Di(tert- butylperoxy)cyclohexane concentration, possibly in view of a target or desired polymerization reaction temperature. A fourth process portion 240 can involve determining a polymerization time period that matches or is close (e.g., as close as possible) to a target or desired polymerization time period. The fourth process portion 240 can involve the identification or selection of a polymerization time period that corresponds or is expected to correspond to a target or minimum desired polymer conversion percentage, possibly with respect to a target or desired polymerization reaction temperature under consideration.

The first through fourth process portions 240 can result in the determination of a set of process parameters (e.g., l,l-Di(tert-butylperoxy)cyclohexane concentration, and one or more of polymerization reaction temperature, polymerization time period, or other parameters) for SAN resin manufacture or production. A fifth process portion 250 involves producing an enhanced or high transparency / reduced or low haze SAN resin having the target haze or transparency value using the process parameters determined in association with the first through fourth process portions 240. The fifth process portion 250 can involve one or more portions of a process in accordance with an embodiment of the present disclosure, such as the process 100 described above with respect to FIG. 1.

One or more aspects of the second process 200 described with respect to FIG. 4 can be automated or computer based, and correspondingly implemented using a computer system, control system, or state machine that is specifically programmed or designed to perform particular operations described above, for instance, by way of execution of stored program instructions.

Particular embodiments of the disclosure are described above for addressing at least one of the previously indicated problems. While features, functions, processes, process portions, advantages, and alternatives associated with certain embodiments have been described within the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages to fall within the scope of the disclosure. It will be appreciated that several of the above-disclosed features, functions, processes, process portions, advantages, and alternatives thereof, may be desirably combined into other different methods, processes, systems, or applications. The above-disclosed features, functions, processes, process portions, or alternatives thereof, as well as various presently unforeseen or unanticipated alternatives, modifications, variations or improvements thereto that may be subsequently made by one of ordinary skill in the art, are encompassed by the following claims.