Liquid compositions including organic peroxides and method of preparing same

Abstract

A liquid organic peroxide composition including: (a) di(tert-butylperoxy)diisopropylbenzene; and (b) at least one aliphatic organic peroxide selected from the group consisting of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, di(tert-amyl) peroxide, di(tert-butyl)peroxide, and 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3. The organic peroxide composition is a homogenous liquid at ambient temperature.

Description

LIQUID COMPOSITIONS INCLUDING ORGANIC PEROXIDES AND METHOD OF PREPARING SAME

[0001] FIELD OF THE INVENTION

[0002] The present invention relates to organic peroxide compositions that are liquid at ambient temperatures and include a combination of aromatic and aliphatic organic peroxides, and methods for preparing such compositions.

[0003] BACKGROUND

[0004] Reference to or discussion of any document or item of information in this specification is not an admission that the document or item of information, or any combination thereof was at the priority date, publicly available, known to the public, part of common general knowledge, or otherwise constitutes prior art under the applicable statutory provisions.

[0005] Polyolefins are used in the industry in products such as packaging films, textiles, pipes, automotives, and the like, which may require extrusion and molding of the polyolefin into desirable shapes for various products. Extrusion and / or molding of polyolefins require cross-linking and / or modification to increase handling efficiency. One such modification process is “vis-breaking” or viscosity breaking to reduce the viscosity and molecular weight of polymers to a target value.

[0006] Organic peroxides participate in the vis-breaking process by breaking down polymer chains through free radical generation, which results in reducing the polymer’s molecular weight and viscosity. In industry, it is preferred that the organic peroxides used in commercial vis-breaking are in a stable liquid form at ambient temperature to facilitate combination of the organic peroxides with polymers and increase process efficiency.

[0007] The majority of the various commercial processes used for the controlled rheology of polypropylene (vis-breaking) requires the use of an ambient temperature liquid organic peroxide. During the vis-breaking process, the ambient liquid peroxide is sprayed into a ribbon blender containing polypropylene (PP) in the form of a granular powder. The final peroxide plus polypropylene powder composition is then conveyed using an auger feeder into the hopper of either a heated twin-screw extruder or a single screw extruder. The residence time of the polypropylene in the extruder is defined by the revolutions per minute (RPM) of the extruder and the length of the barrel. The combination of extruder residence time, extruder temperature, and barrel and die temperatures are established to ensure 100% of the organic peroxide is decomposed during this process. In summary the time-temperature profile of the extrusion process is selected to provide complete peroxide decomposition. At the exit or end of the extruder is a heated die configuration connected to an underwater pelletizer to create pellets of vis-broken PP.

[0008] Other ways to introduce the liquid organic peroxide to the polypropylene is by direct injection into the side of an extruder, while simultaneously feeding PP pellets or powder into the extruder hopper, or spraying the liquid peroxide into the hopper while simultaneously adding either powder or pellets of the polypropylene into the same hopper of the extruder. When performing the latter spray process, the goal is to ensure the ambient liquid peroxide directly contacts the PP pellets or powder being fed into the hopper and there is very minimal to no contact with the hopper’s interior metal surface. Making sure the liquid peroxide spray only contacts the PP entering the hopper is very important to prevent inconsistent PP modification during the spray process.

[0009] It is also desirable to use lesser amounts of organic peroxide in these industrial processes to reduce cost. At the same time, processes that do not generate any undesirable residue and / or have minimal to no odor are preferred to reduce manufacturing steps. A liquid form of organic peroxide that is stable at ambient temperature is particularly desired by the major polymer manufacturers who conduct controlled rheology of polymers, especially polypropylene, on an industrial scale.

[0010] One group of organic peroxides commonly used in cross-linking or vis-breaking of polymers includes aromatic dialkyl peroxides. However, aromatic dialkyl organic peroxides are generally solid at ambient temperature, and thus, need to be heat processed to be in liquid form for inclusion in the vis-breaking process. Additionally, decomposition of these aromatic organic peroxides generates solid decomposition products that result in bloom, an undesirable crystalline residue present on the surface of a cured polymer that can modify material properties of the cured polymer.

[0011] When such aromatic dialkyl peroxides are used in liquid form, the liquid compositions generally include a primary aromatic dialkyl peroxide, e.g., di(tert-butylperoxyjdiisopropylbenzene, in combination with additional aromatic organic peroxides, referred to herein as “additive aromatic peroxides”. The additive aromatic peroxides need to be incorporated in all such ambient temperature liquid peroxide compositions that include a primary aromatic dialkyl peroxide such as di(tert-butylperoxyjdiisopropylbenzene to maintain the composition in liquid form and prevent the separation of the composition into non-homogeneous liquid and solid layers during ambient temperature storage. Some examples of such additive aromatic peroxides used in industrial cross-linking and other polymer modification processes include dicumylperoxide or t-butyl cumyl peroxide, which have chemical structures (I) and (II), respectively:CH3CH3H3c-d-o- o-d— <6H36H3(II).

[0012] Unfortunately, the thermal decomposition of such additive aromatic peroxides generates acetophenone as a by-product. Acetophenone has an unpleasant and pungent odor that permeates the final modified polymer or crosslinked polymer / elastomer product made with these “additive aromatic peroxide" blends. This acetophenone odor is unacceptable for the PP vis-breaking market and is also unacceptable for certain rubber and polymer crosslinking market applications (for example, in automotive under-the-hood hose, belt and gasket parts). Furthermore acetophenone is also a mild irritant to skin and eyes.

[0013] Another drawback of these liquid aromatic peroxide compositions is that the thermal reactivity of the additive aromatic peroxides significantly differs from the thermal reactivity of the primary aromatic peroxide, e.g., di(tert-butylperoxy) diisopropylbenzene. For a more consistent and predictable reaction in in an industrial or commercial process, it is desirable for different peroxides in the liquid composition to have similar half-life decomposition characteristics; that is, it is preferable that all organic peroxides in a given composition have similar thermal decomposition properties.

[0014] Various attempts have been made to address these drawbacks of using organic peroxides in polymer processing.

[0015] US Patent No. 10,344,142 describes using crosslinking coagents like triallyl cyanurate (TAC), which contains a heterocyclic ring with three pendant groups containingreactive allyl ic (unsaturated) functionality, as a “reactive solvent” to create liquid peroxides that can be further blended with jasmine and rose oils.

[0016] US Patent No. 5,981,805 describes a blend of aromatic organic peroxide di(tert-butylperoxy)diisopropyl benzene, having a tailored meta-isomer to para-isomer ratio to maintain the organic peroxide in the form of a lower melting solid (but still solid at ambient temperatures), and a tertiary alkyl cumyl peroxide (e.g., tert-butyl peroxy isopropropyl benzene) which is also an aromatic organic peroxide, to produce a peroxide composition that is liquid at ambient temperature.

[0017] U. S. Patent No. 4,450,302 describes the preparation of novel blends of aromatic organic dialkyl peroxides that have a melting point of about 5°C, and are thus liquid at ambient temperature, where the blends include aromatic t-butyl cumyl peroxide aka (tertbutylperoxyisopropylbenzene), aromatic di(tert-butylperoxy)diisopropyl benzene and aromatic dicumyl peroxide.

[0018] US Patent No. 4,847,232 describes specific compositions of di(tert-butylperoxy)diisopropyl benzene with other aromatic peroxides such as dicumyl peroxide and t-butyl cumyl peroxide.

[0019] US Patent No. 5,719,096 describes a blend of two aromatic organic peroxides comprising aromatic di(tert-butylperoxy)diisopropyl benzene and aromatic di(t- amylperoxy)diisopropyl benzene, which is a liquid or low melting solid composition.

[0020] While the use of a blend of the aromatic peroxides, as known in the art, will result in liquid organic peroxide compositions that remain liquid at ambient temperatures, such liquid peroxide compositions have an undesirable odor because of the generation of acetophenone as a decomposition byproduct as described herein.

[0021] Thus, there is a real industrial need for an organic peroxide composition where the final peroxide composition is a liquid at ambient temperature but does not generate bloom and / or create acetophenone. It has not been possible until now to create such an ambient liquid peroxide composition that includes aromatic dialkyl organic peroxides. This invention addresses these drawbacks by creating an ambient liquid peroxide composition that combines aromatic dialkyl peroxide(s) with aliphatic dialkyl peroxide(s).

[0022] SUMMARY

[0023] The organic peroxide containing composition of this invention addresses the above-described drawbacks in cross-linking, vis-breaking and other polymer modification processes by providing a homogenous organic peroxide composition that is liquid at ambient temperature, while providing both low odor and bloom-free performance when crosslinking or modifying polymers.

[0024] An embodiment is directed to a liquid organic peroxide composition comprising: (a) di(tert-butylperoxy)diisopropylbenzene; and (b) at least one aliphatic organic peroxide selected from the group consisting of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, di(tert-amyl) peroxide, di(tert-butyl)peroxide, and 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3.

[0025] Another embodiment is directed to a method of preparing a liquid organic peroxide composition, the method comprising: mixing di(tert-butylperoxy)diisopropylbenzene and at least one aliphatic organic peroxide selected from the group consisting of 2,5-dimethyl- 2,5-di(tert-butylperoxy)hexane, di(tert-amyl) peroxide, di(tert-butyl)peroxide, and 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3.

[0026] The embodiments described herein may further include stirring the di(tert-butylperoxy)diisopropylbenzene and the at least one aliphatic organic peroxide for 72 hours at ambient temperature.

[0027] The embodiments described herein my further include melting the di(tert-butylperoxy)diisopropylbenzene and adding molten di(tert- butylperoxy)diisopropylbenzene to at least one ambient temperature aliphatic organic peroxide with stirring to instantaneously produce a peroxide composition that remains a homogeneous liquid at ambient temperatures.

[0028] Another embodiment is directed to a method of controlling rheology of a polymer, the method including: blending a liquid organic peroxide composition with a polymer to form a homogenous mixture; and subjecting the homogenous mixture to a vis-breaking process, where the liquid organic peroxide composition comprises di(tert-butylperoxy)diisopropylbenzene, and at least one aliphatic organic peroxide selected from the group consisting of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, di(tert-amyl) peroxide, di(tert-butyl)peroxide, and 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, and the organic peroxide composition is a homogenous liquid at ambient temperature.

[0029] Another embodiment is directed to a method of cross-linking a polymer, the method including: mixing a liquid organic peroxide composition and a polymer: and curing using a time-temperature profile such that at least 95 wt% or more of the peroxide, and more preferably 100% of the peroxide is decomposed during the process; where the liquid organic peroxide composition comprises di(tert-butylperoxy)diisopropylbenzene, and at least one aliphatic organic peroxide selected from the group consisting of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, di(tert-amyl) peroxide, di(tert-butyl)peroxide, and 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3; more preferably selected from 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and di(tert-amyl) peroxide; and the organic peroxide composition is a homogenous liquid at ambient temperature.

[0030] Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

[0031] BRIEF DESCRIPTION OF DRAWINGS

[0032] Drawings are provided herewith for better understanding of the invention, and illustrate the principles and features of the invention The Drawings are not necessarily to scale and are not meant to limit the invention. In the Drawings, like numerals are used to indicate like parts throughout the various views.

[0033] FIGURE 1 is a rheograph of the Elastic Modulus (Max S’) in dN-m of an EPDM elastomer over time of Example 2, measured at 175°C, comparing the use of 3.00 phr of solid Vul-Cup® R peroxide to 3.64 phr of the liquid peroxide of this invention.

[0034] FIGURE 2A is a photograph of an EPDM disc that is cured with 3.00 phr Vul-Cup® R and stored for 1 month at ambient temperature, which formed undesirable crystals of bloom on the surface. FIGURE 2B is a photograph of an EPDM disc that is cured with 3.64 phr of the liquid peroxide composition of Example 1 and stored for 6 months at ambient temperature, showing a clean, desirable surface with no crystal formation.

[0035] FIGURE 3 is a graphical representation of measured real viscosity q’ (Pa. sec) of polypropylene at 190°C versus ω frequency (Radians / sec) for the unmodified control polypropylene (no peroxide used) compared to vis-broken polypropylene modified with600 ppm of Luperox® 101BR versus 600 ppm of the novel liquid peroxide blend of this invention, provided in Table 2, Example 1, for the controlled rheology (vis-breaking) of polypropylene of Example 3.

[0036] FIGURE 4 is a graphical representation of the G’ Elastic Modulus of polypropylene in Pascal (Pa) at 190°C versus frequency for the unmodified control polypropylene (no peroxide used) compared to vis-broken polypropylene modified with 600 ppm of Luperox® 101 BR and vis-broken polypropylene modified with 600 ppm of the novel liquid peroxide blend of this invention, provided in Table 2, Example 1, for the controlled rheology (vis-breaking) of polypropylene of Example 3.

[0037] FIGURE 5 is a graphical representation of measured real viscosity q’ (Pa. sec) at 190°C versus ω frequency (Radians / sec) for the unmodified control polypropylene (no peroxide used) compared to vis-broken polypropylene modified with 600 ppm of Luperox® DTA and vis-broken polypropylene modified with 600 ppm of the novel liquid peroxide blend of this invention provided in Table 4, Example 4, for the controlled rheology (vis-breaking) of polypropylene of Example 5.

[0038] FIGURE 6 is a graphical representation of the G’ Elastic Modulus of polypropylene in Pascal (Pa) at 190°C versus frequency for the unmodified control polypropylene (no peroxide used) compared to vis-broken polypropylene modified with 600 ppm of Luperox® DTA and vis-broken polypropylene modified with 600 ppm of the novel liquid peroxide blend of this invention provided in Table 4, Example 4, for the controlled rheology (vis-breaking) of polypropylene of Example 5.

[0039] DETAILED DESCRIPTION

[0040] Hereinafter various aspects of the present invention will be described in detail.

[0041] Any compositions described herein are intended to encompass compositions which consist of, consist essentially of, as well as comprise, the various constituents identified herein, unless explicitly indicated to the contrary.

[0042] As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Additionally, the use of “or” is intended to include “and / or”, unless the context clearly indicates otherwise.

[0043] As used herein, the recitation of a numerical range for a variable is intended to convey that the variable can be equal to any value(s) within that range, any and all sub¬ ranges encompassed by the broader range, including any integer value(s) within that range as well as the upper and lower limits unless explicitly indicated to the contrary.

[0044] As used herein, "about" is a term of approximation that would be understood by one of skill in the art, and is intended to include minor variations such as, for example, standard deviations associated with techniques commonly used to measure the amounts of the constituent elements or components of an alloy or composite material, or other properties and characteristics. All of the values characterized by the above-described modifier "about," are also intended to include the exact numerical values disclosed herein. Moreover, all ranges include the upper and lower limits.

[0045] As used herein, the term “aromatic organic peroxide” refers to a peroxide compound containing a planar unsaturated ring of atoms that is stabilized by an interaction of the bonds forming the ring. Such compounds are typified by including at least one benzene ring and / or its derivatives.

[0046] As used herein, the term “aliphatic organic peroxide” refers to a non-aromatic peroxide.

[0047] As used herein, the terms “vis-breaking” and “controlled rheology” are used interchangeably, and refers to a process of modifying the viscosity and / or molecular weight of a polypropylene homopolymer, and includes but is not limited to a vis-breaking process that includes the use of the liquid organic peroxide composition described herein. This process lowers the polypropylene molecular weight to reduce polymer viscosity (hence the term controlled rheology).

[0048] The polymer modification processes described herein can be applied to polymers other than polypropylene, for example polyethylene and polyethylene copolymers, polyamides, polylactic acid and polyhydroxyalkanoates to produce branched polymers that have higher molecular weight, higher viscosity, higher melt, strength, higher tensile strength and impact strength while remaining thermoplastic. When conducting polymer melt flow modification (other than for polypropylene), low concentrations of organic peroxide, for example, from about 10 ppm to 10,000 ppm, or from about 50 ppm to about 5000 ppm, or from about.50 ppm to 500 ppm, and the like, may be used depending upon the polymer chosen and its initial molecular weight and desired final physical properties or industrial application. The organic peroxide concentration for these applications can be equal to any ratio(s) within any of these ranges, including the end-points of these ranges.

[0049] As used herein, the term “bloom” refers to the process of forming crystalline residue of an additive material on the surface of a cured polymer as well as the crystalline residue formed on the surface of an uncured polymer.

[0050] As used herein, the term “ambient temperature” refers to the average air temperature in a given environment that, is measured with a thermometer, and ranges from 15’C to 30°C.

[0051] As used herein, the terms “liquid” and “in liquid form” mean that the corresponding material is in the form of a homogenous (no layers or solids) liquid (flowable or pourable) at the temperature recited, or in the absence of a specific recited temperature, at ambient temperature.

[0052] As used herein, the term “stable” with respect to organic peroxide formulations, compositions or blends described herein describes formulations (or compositions or blends) that do not undergo immediate decomposition at ambient temperature, i.e., they are “thermally stable” at ambient temperatures, and do not require refrigerated storage to maintain the % assay of the organic peroxide.

[0053] As used herein, “phr" denotes parts by weight of a peroxide or peroxide composition per one-hundred parts by weight, of a polymer or elastomer.

[0054] As used herein, “ppm” denotes parts by weight of a peroxide or peroxide composition per one-million parts by weight of a polymer or elastomer.

[0055] Peroxide names and physical properties for the organic peroxides described herein can be found in “Organic Peroxides” by Jose Sanchez and Terry N. Myers; Kirk-Othmer Encyclopedia of Chemical Technology, Fourth Ed., Volume 18, (1996), the disclosures of which are incorporated herein by reference.

[0056] Unless indicated otherwise, each individual feature, aspect or embodiment described herein is combinable with any other individual feature(s), aspect(s) or embodiment(s) that is / are described herein, without limitation. Such combinations arespecifically contemplated as being within the scope of the present invention, regardless of whether they are explicitly described as a combination herein.

[0057] Technical and scientific terms used herein have the meaning commonly understood by one of skill in the art to which the present description pertains, unless otherwise defined.

[0058] Polyolefins are used in the industry in products such as packaging films, fiber, non-wovens, textiles, pipes, automotives, and the like, which may require extrusion and / or molding of the polyolefin into desirable product shapes, e.g., face masks, baby diapers, food packaging, disposable syringes, containers, tubing, gaskets, hoses, etc. Extrusion and / or molding of polyolefins require cross-linking and / or modification of such polyolefins to increase handling efficiency. Such modification processes commonly used in industry include vis-breaking, cross-linking and the like.

[0059] Aromatic dialkyl peroxides are a group of organic peroxides commonly used in the vis-breaking process of polymers. Di(tert-butylperoxy)diisopropylbenzene is one such solid, aromatic functionalized dialkyl organic peroxide that is used in industrial vis¬ breaking processes. However its use in industrial processes for vis-breaking of PP is very limited as it is a solid at ambient temperature. Many commercial processes require aromatic dialkyl peroxides, such as di(tert-butylperoxy)diisopropylbenzene, to be sprayed, injected or pumped into a polymer, which, in turn, requires that the peroxide is present in its liquid form. To facilitate ease of use, solid di(tert- butylperoxyjdiisopropylbenzene peroxide (Vul-Cup® R) can be converted to the liquid form by heating to a temperature above its melting point (e.g., 55°C). The solid pure para isomer of this peroxide has a melting point of 80°C. However, significant operationalcosts are associated with keeping such organic peroxide compositions heated in liquid form over a sustained period of time, for example, by circulating hot water through the peroxide-storage containers. Such hot, molten liquid organic peroxides are then sprayed on polymer(s), e.g., in the form of polymer pellets, before being extruded for use in wire and cable manufacturing operation processes.

[0060] During spraying of the hot, molten di(tert-butylperoxy)diisopropylbenzene on polymer pellets, a portion of the peroxide migrates to the pellet surface and re-solidifies as it cools to ambient temperature. This results in an inhomogeneous blend of the polymer pellets and re-solidified pure peroxide powder on the surface of the polymer pellets. Additionally, handling of hot molten liquid peroxide and maintaining the peroxide in its liquid form during a pumping process, for example, while feeding into a spray unit or compounding equipment through tubes or pipes, also raises various safety and engineering issues and increases equipment costs.

[0061] To reduce such costs and increase safety and efficiency, several commercial ambient liquid organic peroxide blends have been developed that include aromatic organic peroxide di(tert-butylperoxy)diisopropyl benzene as a primary organic peroxide blended with other aromatic organic peroxides (“additive aromatic peroxides”). Essentially, these are blends of only aromatic organic peroxide types, using the “like dissolves like", principal. Inclusion of such additive aromatic peroxides is necessary to maintain the composition in liquid form, and prevent the formation of non-homogeneous layers of liquid during storage at ambient temperatures. However, as discussed herein, inclusion of these additive aromatic peroxides results in the generation of acetophenone as a by-product that imparts a pungent and unpleasant odor to the composition and alsoimparts inconsistencies in the reaction parameters. The invention described herein addresses these drawbacks in organic peroxide compositions that are used in industrial polymer vis-breaking processes. Moreover, the organic peroxide composition described herein can also be used for polymer cross-linking and other polymer modification processes, and reduces the complexity and cost of such processes.

[0062] The inventive liquid organic peroxide compositions are homogeneous compositions at ambient temperature and require no added heat to maintain the composition in the desirable liquid form. In one or more embodiments, a novel organic peroxide composition includes di(tert-butylperoxy)diisopropylbenzene as a primary component thereof in combination with one or more aliphatic organic peroxides.

[0063] An embodiment is directed to a liquid organic peroxide composition comprising: (a) di(tert-butylperoxy)diisopropylbenzene; and (b) at least one aliphatic organic peroxide selected from the group consisting of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, di(tert-amyl) peroxide, di(tert-butyl)peroxide, and 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3.

[0064] Another embodiment is directed to a method of preparing a liquid organic peroxide composition, the method comprising: mixing di(tert-butylperoxy)diisopropylbenzene and at least one aliphatic organic peroxide selected from the group consisting of 2,5-dimethyl- 2,5-di(tert-butyiperoxy)hexane, di(tert-amyl) peroxide, di(tert-butyl)peroxide, and 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3.

[0065] The embodiments described herein may further include stirring the di(tert-butylperoxy)diisopropylbenzene and the at least one aliphatic organic peroxide for 72 hours at ambient temperature.

[0066] The embodiments described herein my further include melting the di(tert-butylperoxy)diisopropylbenzene and adding molten di(tert-butylperoxy)diisopropylbenzene to at least one ambient temperature aliphatic organic peroxide with stirring to instantaneously produce a peroxide composition that remains a homogeneous liquid at ambient temperatures.

[0067] Another embodiment is directed to a method of controlling rheology of a polymer, the method including: blending a liquid organic peroxide composition with a polymer to form a homogenous mixture; and subjecting the homogenous mixture to a vis-breaking process, where the liquid organic peroxide composition comprises di(tert- butylperoxy)diisopropylbenzene; and at least one aliphatic organic peroxide selected from the group consisting of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, di(tert-amyl) peroxide, di(tert-butyl)peroxide, and 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, and the organic peroxide composition is a homogenous liquid at ambient temperature.

[0068] Another embodiment is directed to a method of cross-linking a polymer, the method including: mixing a liquid organic peroxide composition and a polymer; and curing using a time-temperature profile such that at least 95 wt% or more of the peroxide is decomposed during the process; where the liquid organic peroxide composition comprises di(tert-butylperoxy)diisopropylbenzene; and at least one aliphatic organic peroxide selected from the group consisting of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, di(tert-amyl) peroxide, di(tert-butyl)peroxide, and 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, and the organic peroxide composition is a homogenous liquid at ambient temperature.

[0069] In any of the embodiments described herein, the organic peroxide composition is a homogenous liquid at ambient temperature.

[0070] In any of the embodiments described herein, the at least one aliphatic organic peroxide is 2,5-dimethyl-2,5-di(t-butylperoxy)hexane.

[0071] In any of the embodiments described herein, the at least one aliphatic organic peroxide is di-t-amyl peroxide.

[0072] In any of the embodiments described herein, the at least one aliphatic organic peroxide is 2,5-dimethyl-2,5-di(t-butylperoxy)hexane and di-t-amyl peroxide.

[0073] In any of the embodiments described herein, the method may include applying heat to melt the di(tert-butylperoxy)diisopropylbenzene prior to combining the di(tert- butylperoxy)diisopropylbenzene and the at least one aliphatic organic peroxide at ambient temperature.

[0074] In any of the embodiments described herein, a weight (wt%) ratio of the di(tert-butylperoxy)-diisopropylbenzene peroxide and the at least one aliphatic organic peroxide is from 20:80 to 80:20.

[0075] In any of the embodiments described herein, a weight (wt%) ratio of the di(tert- butylperoxy)-diisopropylbenzene peroxide and the at least one aliphatic organic peroxide is 42:58.

[0076] In any of the embodiments described herein, a weight (wt%) ratio of the di(tert-butylperoxy)-diisopropylbenzene peroxide and the at least one aliphatic organic peroxide is 50:50.

[0077] In the embodiments described herein, the di(tert-butylperoxy)diisopropylbenzene comprises a blend of meta- and para-isomers of the di(tert-butylperoxy)-diisopropylbenzene, and wherein the meta-isomer to the para-isomer weight (wt%) ratio is from 60:40 to 90:10.

[0078] In the embodiments described herein, the meta-isomer to the para-isomer weight (wt%) ratio is 61.6:38.4.

[0079] In the embodiments described herein, the meta-isomer to the para-isomer weight (wt%) ratio is 78:22.

[0080] In other embodiments described herein, the di(tert-butylperoxy)diisopropylbenzene may comprise either 100% meta isomer or 100% para isomer.

[0081] Aliphatic dialkyl peroxides that are known to participate in the vis-breaking of polymers are contemplated as suitable for use in the liquid organic peroxide compositions described herein. Non-limiting examples of such dialkyl peroxides include 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, di(tert-amyl) peroxide, di(tert-butyl)peroxide, and 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, preferably 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and di(tert-amyl) peroxide. These peroxides can be used in one or more combinations including any two or more peroxides listed herein. Other non-limiting examples of aliphatic dialkyl type peroxides that are suitable for use in the liquid organic peroxide compositions described herein include 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxonane and 1,2,4,5,7,8-hexoxonane, 3,6,9-trimethyl-3,6,9-tris(ethyl (Et) and propyl (Pr)) derivatives which are commercially available as 40% assay dilutions using an aliphatic safety solvent. This aliphatic safety solvents prevent shock-sensitive solid crystal formation in commercially-available cyclic aliphatic organic peroxides. However, the presence of this aliphatic safety solvent in a peroxide composition may be undesirablewhen modifying PP polymers for certain food-contact applications. The novel liquid ambient temperature compositions of this invention comprising alkyl and aromatic peroxide blends, e.g. blending di(tert-butylperoxy)diisopropylbenzene and / or 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, and di-t-amyl peroxide eliminates the need of an aliphatic safety solvent when choosing to use one or more of the other non-limiting peroxides selected from 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxonane and 1,2,4,5,7,8-hexoxonane, 3,6,9-trimethyl-3,6,9-tris(ethyl (Et) and propyl (Pr)) derivatives.

[0082] The aromatic organic peroxides dicumyl peroxide and tert-butyl cumyl peroxide are excluded from the liquid organic peroxide compositions of this invention, as are peroxyesters, diperoxyketals, hydroperoxides, monoperoxycarbonates, peroxydicarbonates, hemi-peroxyketals, and simple ketone peroxides.

[0083] One or more embodiments includes a novel liquid organic peroxide composition that does not include any additional solvents, oils, monomers, crosslinking coagents (e.g., triallyl cyanurate; trimethylolpropane trimethacrylate), antioxidants and / or free-radical trapping agents.

[0084] In any of the embodiments described herein, the novel liquid organic peroxide composition is non-aqueous.

[0085] In any of the embodiments described herein, the novel liquid organic peroxide composition includes di(tert-butylperoxy)diisopropylbenzene in combination with one or more other aliphatic dialkyl type peroxides.

[0086] In any of the embodiments described herein, the novel liquid organic peroxide composition includes di(tert-butylperoxy)-diisopropylbenzene in combination with 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and / or di(tert-amyl) peroxide and di(t-butyl) peroxide.

[0087] In any of the embodiments described herein, a novel liquid organic peroxide composition includes a blend of di(tert-butylperoxy)diisopropylbenzene and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane or a blend of di(tert-butylperoxy)diisopropylbenzene and di-t-amyl peroxide.

[0088] In any of the embodiments described herein, a novel liquid organic peroxide composition includes a blend of di(tert-butylperoxy)diisopropylbenzene and 3,6,9-triethyl- 3.6.9-trimethyl-1,4,7-triperoxonane, 1,2,4,5,7,8-hexoxonane, and / or 3,6,9-trimethyl- 3.6.9-tris(Et and Pr) derivatives.

[0089] In any of the embodiments described herein, a novel liquid organic peroxide composition includes a blend of di(tert-butylperoxy)diisopropylbenzene in combination with 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and / or di(tert-amyl) peroxide, and 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxonane, 1,2,4,5,7,8-hexoxonane, and / or 3,6,9-trimethyl-3,6,9-tris(Et and Pr) derivatives.

[0090] In any of the embodiments described herein, the liquid peroxide composition can further include a food-grade mineral oil (also known as white mineral oil) to further dilute the liquid peroxide compositions. White mineral oil is a mixture of liquid hydrocarbons, essentially paraffinic and naphthenic in nature and obtained from petroleum, that is refined to meet test requirements of United State Pharmacopeia pertaining to Food for Human Consumption. Addition of the food-grade mineral oil to the peroxide composition reduces the % peroxide content of the liquid peroxide for more accurate metering or spraying in a commercial vis-breaking operation.

[0091] Any polymer or elastomer that can be crosslinked, grafted or modified by free radicals can be subjected to crosslinking in the presence of the organic peroxide compositions described herein. Such polymers will react to form a solid (thermoset) article when combined with the organic peroxide formulations described herein and heated. Non-limiting examples of such crosslinkable polymers include polyethylene such as linear low density (LLDPE), low-density polyethylenes (LDPE), high-density polyethylenes (HDPE), CPE (chlorinated polyethylene), polyamides, PLA (polylactic acid), PHA (Polyhydroxyalkanoates), polyhydroxybutyrate, ethylene-vinyl acetate polymers (EVA), ethylene-propylene rubbers such as ethylene-propylene copolymers (EPM) and terpolymers (EPDM), nitrile butadiene rubber(NBR), hydrogenated nitrile butadiene rubber (HNBR), bromobutyl rubber (BIIR), fluorocarbon-based fluoroelastomers (FKM), silicone rubbers (VMQ), and the like.

[0092] A preferred polymer is isotactic homopolypropylene that undergoes controlled degradation (vis-breaking) instead of cross-linking when modified with organic peroxides, and such controlled degradation results in a desirable increase in the polypropylene melt flow index and a decrease in its molecular weight and viscosity. Commercial PP copolymers containing ~2wt% ethylene co-monomer as an impact modifier can also be modified.

[0093] Another preferred polymer are ethylene-propylene rubbers, e.g., EPR and EPDM, that undergo cross-linking in the presence of the organic peroxides.

[0094] The concentration range of liquid peroxide required to vis-break polypropylene depends upon the final end-use application and viscosity of the starting PP polymer to be vis-broken. For example, creation of fibers for meltblown processes to make non-wovensfor fabric, industrial and residential air filtration and face masks requires a low viscosity PP with a MFI (Melt Flow Index) in the range of about 900 g / 10min to 1,600 g / 10min at 230° with a 2.16 kg load as per ASTMD1238. Thus, the amount of peroxide required can range from about 900 ppm to about 5,000 ppm, or from about 1000 ppm to about 4500 ppm, or from about 1200 ppm to about 4000 ppm, or from about 1500 ppm to about 4000 ppm, or from about 1600 ppm to about 4000 ppm, or from about 1700 ppm to about 4000 ppm, or from about 1800 ppm to about 4000 ppm, or from about 1900 ppm to about 4000 ppm, or from about 2000 ppm to about 4000 ppm, or from about 2500 ppm to about 4000 ppm, or from 3000 ppm to about 4000 ppm, and the like. The amount of peroxide can be equal to any ratio(s) within any of these ranges, including the end-points of these ranges.

[0095] For various molding applications (injection molding, compression molding, blow molding) and extrusion operations involving polypropylene twine, spunbond fiber and / or hot melt adhesives, the amount of peroxide required can range from about 5 ppm to 1,000 ppm, from about 10 ppm to 900 ppm, from about 20 ppm to 800 ppm, from about 25 ppm to 750 ppm, from about 25 ppm to 700 ppm, from about 25 ppm to 600 ppm, from about 25 ppm to 500 ppm, from about 25 ppm to about 400 ppm, from about 50 ppm to 400 ppm, from about 100 ppm to 850 ppm, from about 150 ppm to 650 ppm, and the like depending upon the starting MFI of the PP to be vis-broken. For example, a fractional MFI grade of PP (< 1 MFI) will require more peroxide, versus a 30 MFI PP grade to achieve the same melt flow index target. The amount of peroxide can be equal to any ratio(s) within any of these ranges, including the end-points of these ranges.

[0096] The polymer undergoing a vis-breaking process in the presence of the novel liquid organic peroxide compositions described herein is thermoplastic. Thermoplasticpolymers are pliable when heated, and harden when cooled. Such thermoplastic polymers can be reused by passing through heating and cooling cycles, for example, in dynamic vulcanization processes to produce Thermoplastic Vulcanizates (TPVs).

[0097] Another aspect of the invention is the suppression of undesirable bloom and odor during the creation of peroxide crosslinked polymeric articles when using the novel liquid organic peroxide compositions described herein. Non-limiting industrial processes for the production of polymeric articles include: compression molding, injection molding, transfer molding; and crosslinking polymers or elastomers using steam tubes or steam autoclave operations. When crosslinking elastomers the amount of peroxide used is generally greater than that used for polymer modification. Peroxide loadings for crosslinking can vary from about 1 phr to about 10 phr, or from about 2 phr to about 8 phr, or from about 3 phr to about 6 phr, and the like. The peroxide loading can be equal to any ratio(s) within any of these ranges, including the end-points of these ranges.

[0098] The novel liquid organic peroxide composition described herein can also be used to graft various unsaturated species with polar acidic functionality onto a polymer. Nonlimiting examples of such species suitable for grafting include anhydrides of maleic acid, itaconic acid, fumaric acid, linolenic acid, vinylsulfonic acid, 3-butenoic acid, acrylic acid, methacrylic acid, and the like.

[0099] An extruder is often used when modifying polymers, thus a liquid form of organic peroxide is highly desired for these processes. The liquid organic peroxide can be either sprayed onto the polymer beads, sprayed onto a polymer in an extruder hopper, or directly injected (using an injector and a pump) into the barrel of an extruder. The unsaturated species to be grafted onto a polymer can be fed separately into an extruder hopper alongwith the pellets of polymer, while simultaneously spraying the liquid organic peroxide into the hopper, or by pumping the liquid peroxide midway into the barrel by a direct injection process.

[0100] The aromatic organic peroxide, di(tert-butylperoxy)diisopropylbenzene, of the novel liquid organic peroxide composition described herein exists as the meta-isomer (Formula A) and para-isomer (Formula B), each of which is suitable for inclusion in the composition described herein:CH3CH3CH3CH3H3C-6-O-O-6^# V- d-o-o-d-cH36H36H36H36H3 parajSomer(Formula A)CH3CH3_H3C-6-O-O-6^#6H36H3' C^CH3H3C"° c~CH3H3C ■ |3meta isomer (Formula B).

[0101] In one or more embodiments, the organic peroxide composition includes a blend of meta- and para-isomers of the di(tert-butylperoxy)- diisopropylbenzene wherein the meta-isomer to the para-isomer weight (wt%) ratio can be in the range of from 100:0 to 0: 100, from 60:40 to 90: 10, from 60:40 to 85: 15, from 60:40 to 80:20, from 60:40 to 75:25, from 60:40 to 70:30, from 65:35 to 85:15, from 65:35 to 80:20, from 65:35 to 75:25, from 65:35 to 70:30, from 70:30 to 75:25, from 70:30 to 80:20, from 70:30 to 85:15, from 70:30 to 90:10, from 75:25 to 80:20, from 75:25 to 85:15, from 75:25 to 90:10, from 80:20 to 90:10, from 85:15 to 90:10, from 80:20 to 85: 5, 60:40, 61:39, 62:38, 63:37, 64:36, 65:35, 66:34, 67:33, 68:32, 69:31, 70:30, 71:29, 72: 28, 73:27, 74:26, 75:25, 76:24, 77:23, 78:22,79:21, 80:20, 81:19, 82:18, 83:17, 84:16, 85:15, 86:14, 87:13, 88:12, 89:11, 90:10, and the like; preferably the ratio meta-isomer to the para-isomer (wt%) ratio of the di(tert-butylperoxy)diisopropylbenzene range from 61.6:38.4 to 78:22. The meta-isomer to the para-isomer weight (wt%) ratio can be equal to any ratio(s) within any of these ranges, including the end-points of these ranges.

[0102] In another embodiment, the novel liquid organic peroxide composition comprises the meta-isomer of di(tert-butylperoxy)diisopropylbenzene.

[0103] In one embodiment, the organic peroxide composition includes < 41.7 wt% of di(tert-butylperoxy)diisopropylbenzene and > 58.3 wt% of an aliphatic dialkyl peroxide, i.e., Luperox® 101BR or Luperox® 101 E.

[0104] In one embodiment, the novel liquid organic peroxide composition includes a blend of < 25 wt% of solid, aromatic peroxide di(tert-butylperoxy)diisopropylbenzene and > 75 wt% of at least one aliphatic organic peroxide.

[0105] In one embodiment, the novel liquid organic peroxide composition includes a blend of < 50 wt% of solid, aromatic peroxide di(tert-butylperoxy)diisopropylbenzene and > 50 wt% of the aliphatic organic peroxide di(tertiary amyl)peroxide.

[0106] In one embodiment, the novel liquid organic peroxide composition includes a blend of < 42 wt% of the solid, aromatic peroxide di(tert-butylperoxy)diisopropylbenzene and > 58 wt% of at least one aliphatic organic peroxide.

[0107] In another embodiment, the novel liquid organic peroxide composition includes a blend of < 42 wt% of the solid, aromatic peroxide di(tert-butylperoxy)diisopropylbenzene and > 58 wt% of the aliphatic organic peroxide 2,5-dimethyl-2,5-di(t-butylperoxy)hexane.

[0108] In one or more embodiments, the organic peroxide composition includes a blend of di(tert-butylperoxy)-diisopropylbenzene peroxide and the aliphatic organic peroxide in a weight (wt%) ratio of from 20:80 to 80:20, from 25:75 to 75:25, from 30:70 to 70:30, from 35:65 to 65:35, from 40:60 to 60:40, from 45:55 to 55:45, 36:64, 37:63, 38:62, 39:61, 40:60, 41:59, 42:58, 43:57, 44:56, 45:55, 46:54, 47:53, 48:52, 49:51, 50:50, 51:49, 52:48, 53:47, 54:46, 55:45, 56:44, 57:43, 58:42, 59:41, 60:40, and the like; preferably the weight (wt%) ratio of the di(tert-butylperoxy)-diisopropylbenzene peroxide and the additive aliphatic organic peroxide is 42:58, 41:59, 40:60, 39:61, 38:62, 37:63, 36:64, 35:65, 34:66, 33:67, 32:68, 31:69, 30:70, and the like; more preferably the weight (wt%) ratio of the di(tert-butylperoxy)- diisopropylbenzene peroxide and the aliphatic organic peroxide is 42:58. The weight (wt%) ratio of the di(tert-butylperoxy)-diisopropylbenzene peroxide and the aliphatic organic peroxide can be equal to any ratio(s) within any of these ranges, including the end-pints of these ranges. The non-bloom, non-odor properties of the novel liquid organic peroxide composition described herein are achieved based on the ratio of the amounts of aromatic and aliphatic organic peroxides included in said composition, and is independent of the individual amounts of each peroxide.

[0109] In another embodiment, the novel liquid organic peroxide composition includes 41 wt% of the solid, aromatic peroxide di(tert-butylperoxy)diisopropylbenzene and 59 wt% of the aliphatic organic peroxide 2,5-dimethyl-2,5-di(t-butylperoxy)hexane.

[0110] The novel organic peroxide composition including di(tert-butylperoxy)diisopropylbenzene and at least one additive aliphatic peroxide surprisingly and unexpectedly formed a stable homogeneous liquid composition at ambient temperatures that contained no solid peroxide residues.

[0111] Additive aliphatic organic peroxide 2,5-dimethyl-2,5-di(tertiary butylperoxy)hexane (Luperox® 101) of the inventive composition has structure (III)):CH3CH3CH3CH3H3C-d-O-O-d-CH2CH2-d-O-O-d-CH3(5H3in3^H3^H30||)

[0112] Additive aliphatic organic peroxide d i (tertiary amyl)peroxide (Luperox® DTA) of the inventive composition has structure (IV)):CH3CH3H3C— CH2-(5-0-0-(5-CH2-CH3ui-l3uri3(IV)

[0113] EXAMPLES

[0114] The principles of the present invention, as well as certain exemplary features and embodiments thereof, will now be described by reference to the following non-limiting examples.

[0115] RHEOLOGY MEASUREMENTS FOR CROSSLINKING EPDM

[0116] Rheometer measurements, to follow the crosslinking of the EPDM elastomer, test method ASTM D5289-12 “Standard Test Method for Rubber Property — Vulcanization Using Rotorless Cure Meters” was used on an Alpha Technologies RPA® 2000 rheometer. Approximately 4.5 grams of an EPDM elastomer composition with a 1.1 g / ml density was used to completely fill the upper and lower dies of the rheometer. The uncured rubber was cut from a pressed sheet formed by placing the compounded rubber extracted from our 50 ml brabender mixer and placing the rubber between two sheets of aluminum and pressing the rubber to a thickness of approximately 1 / 8thof an inch using a carver press set to a temperature of 65°C to provide improved rubber flow, but not high enough to cause a crosslinking reaction. Then, using a metal hand held punch, smallround discs about 1.25 inch diameter were created from this sheet. Enough rubber disks were gathered together to obtain a 4.5 gram sample for testing. The final 4.5 gram sample of uncured rubber was placed between two Dartek® sheets. This sandwich of the rubber disk between Dartek® sheets was then placed in the RPA® 2000 rheometer for testing following ASTM D5289-12 testing protocol using a 1°arc (equivalent to a 14% strain), 100 cpm frequency and at 175°C for an isothermal cure temperature.

[0117] DYNAMIC TESTING OF POLYPROPYLENEPolypropylene was both reacted and tested using the Alpha Technologies RPA® 2000 rheometer following a modified version of ASTM D6204 Part A test method, (Standard Test Method for Rubber— Measurement of Unvulcanized Rheological Properties Using Rotorless Shear Rheometers) wherein samples of polypropylene containing organic peroxide were first subjected to a five minute reaction time at 190°C to fully decompose the organic peroxide composition. After the five minute hold time (reaction time with no applied strain or frequency) at 190°C, the rheometer began a frequency sweep from 1 to 227 radians / sec using an applied strain of 20% or 0.0249 Radians. NOTE: The ASTM D6204 Part A method teaches to use a 7% applied strain; however to increase the sensitivity of this test, a 20% applied strain was used when testing polypropylene. The control sample of the virgin Profax® 6301 polypropylene powder with no peroxide was also run on the Alpha Technologies RPA® 2000 rheometer for comparison purposes using the exact same conditions.

[0118] MATERIALS USED IN EXAMPLES

[0119] Aromatic organic peroxide -Vul-Cup® R (di(tert-butylperoxy)diisopropylbenzene)

[0120] Aliphatic organic peroxides - Luperox® 101 BR (2,5-dimethyl-2,5-di(t- butylperoxy)hexane and Luperox® DTA (di-tert-amyl peroxide)

[0121] Elastomer - Vistalon® 2504 EPDM (ethylene propylene diene terpolymer)

[0122] Primol® 352 process oil (white mineral oil (petroleum) viscosity > 20.5 CST)

[0123] VW WEPDM Masterbatch was prepared from the components listed in Table 1:

[0124] TABLE 1VW EPDM MasterbatchIngredient Parts by weight Vistalon® 2504 EPDM 100.00N550 Carbon Black 100.00Primol® 352 process oil 40.00PEG (polyethylene glycol) 3.00TMQ (1,2-dihydro-2,2,4-trimethylquinoline) 1.00Total parts of EPDM Masterbatch 244.00

[0125] EXAMPLE 1 - FIRST NOVEL LIQUID PEROXIDE COMPOSITION

[0126] A first novel liquid organic peroxide composition according to an embodiment of this application was prepared from the components listed in Table 2:

[0127] TABLE 2Organic Peroxide Amount wt%Blend (grams)Vul-Cup® R 208.33 41.67%Luperox® 101 BR 291.67 58.33%Total organic 500.00peroxide

[0128] Specifically, 208.33 grams of solid pieces of the aromatic peroxide di(tert-butylperoxy)diisopropylbenzene (Vui-Cup® R) were added to a clear glass bottle containing a magnetic stirrer and 291.7 grams of liquid, aliphatic peroxide 2,5-dimethyl-2,5-di(t-butylperoxy)hexane (Luperox® 101BR). The clear glass bottle was then placed on a magnetic stir plate with no applied heat and the mixture of the aromatic and aliphatic organic peroxides was stirred for four hours at ambient temperature. At the end of this stirring period, both solid particles of the aromatic peroxide di(tert-butylperoxy)diisopropylbenzene and liquid, non-aromatic aliphatic peroxide 2,5-dimethyl-2,5-di(t-butylperoxy)hexane were visually observed. That is, a homogenous composition was not observed at the end of the stirring period. The stirring was stopped, and the clear glass bottle was allowed to stand, unstirred and at ambient temperature for at least 72 hours. At the end of the at least 72 hour period, a homogeneous, clear liquid peroxide composition was visually observed inside the clear glass bottle. This homogenous liquid peroxide composition was then stored in the same clear glass bottle for six months at ambient temperature. No solid crystals were observed inside the glass bottle after six months, and the composition remained as a homogeneous, clear liquid. This observation confirmed, unexpectedly, the presence of a stable, homogeneous blend of an aromatic peroxide and an aliphatic peroxide. This observation was highly unexpected as it is not expected that a solid aromatic dialkyl organic peroxide would be soluble in an aliphatic dialkyl organic peroxide. Without being constrained by a specific theory, the inventorsbelieve that these unexpected observations are achieved by combining the aromatic and aliphatic organic peroxides in the ratios described herein.

[0129] EXAMPLE 2 - CROSSLINKING EDPM MASTERBATCH WITH NOVEL ORGANIC LIQUID PEROXIDE COMPOSITION OF EXAMPLE 1

[0130] A first sample of the EPDM masterbatch of Table 1 was crosslinked using the novel liquid peroxide composition of Example 1 and a second sample of the EPDM masterbatch was crosslinked using the aromatic organic peroxide (Vul-Cup® R) as the respective curing agents. The amounts of each curing agent was adjusted in the EPDM masterbatch to achieve equal amounts of crosslinking in the first and second samples. Curing was performed at 175°C for 30 minutes.

[0131] Rheology measurements and dynamic testing, as described herein, were performed on the EPDM samples.

[0132] The curing properties of the novel liquid peroxide composition of Example 1 (combination of di(tert-butylperoxy)diisopropylbenzene and 2,5-dimethyl-2,5-di(t-butylperoxy)hexane) and di(tert-butylperoxy)diisopropylbenzene (Vul-Cup® R) alone were compared by measuring the relative degree of cross-linking (Max S' - Min S'), scorch time and cure time, as shown in Table 3:

[0133] TABLE 33.0 phr Vul-Cup® R 3.64 phr Liquid Peroxide Composition of Example 1 Max S’ (MH) (dNm) 31.418 31.644Min S' (ML) (dNm) 1.429 1.522Max S' - Min S' (dNm) 29.989 30.122Scorch Time (min) at 1 dNm 0.51 0.53Time (min) to 90% cure 9.35 10.35

[0134] FIGURE 1 is a rheograph of the Elastic Modulus (Max S’) in dNm versus time at 175°C. As shown in FIG. 1, the elastic properties of a polymer cured with the novel organic peroxide composition described herein is similar to the elastic properties of rubber cured with an aromatic organic peroxide alone without significantly increasing the total amount of the peroxides.

[0135] The cured EPDM elastomer samples were stored at room temperature. After as little as one month, crystals began to appear on the surface of the EPDM rubber sample cured with Vul-Cup® R, as shown in FIGURE 2A. However, no crystals were observed on the surface of the EPDM rubber cured with the novel liquid peroxide composition of Example 1 after one month and six months of storage at ambient temperature. As shown in FIGURE 2B, the surface of the EPDM rubber cured with the novel liquid peroxide composition of Example 1 remained black, clean and shiny after 6 months of storage at ambient temperature.

[0136] EXAMPLE 3A - CONTROLLED RHEOLOGY (VIS-BREAKING) OF POLYPROPYLENE USING NOVEL LIQUID ORGANIC PEROXIDE COMPOSITION OF EXAMPLE 1

[0137] Vis-breaking of polypropylene was carried out using the novel liquid peroxide composition of Example 1. Specifically, 0.0300g of the liquid peroxide composition of Example 1 was added to 50.000g Profax® 6301 polypropylene granular powdered polymer. The liquid peroxide was uniformly dispersed on the PP powder using a high speed bullet blender. This sample of powdered polypropylene contained the liquid peroxide composition of Example 1 at a concentration of 600 ppm (parts per million).

[0138] Using an Alpha Technologies RPA® 2000 rheometer, samples of polypropylene were subjected to a five (5) minute reaction at 190°C to fully decompose the organic peroxides. After the five-minute hold time at 190°C, the rheometer began a frequency sweep from 1 radians / sec to 227 radians / sec using an applied strain of 20% or 0.0249 Radians.

[0139] EXAMPLE 3B - CONTROLLED RHEOLOGY (VIS-BREAKING) OF POLYPROPYLENE USING ONLY ALIPHATIC ORGANIC PEROXIDE

[0140] A comparative example was carried out as described in Example 3A, except 0.0300 g of Luperox® 101BR, 600 ppm was added to 50.000 g of Profax® 6301 polypropylene reactor granular powder and blended to a homogenous composition using a bullet blender. Measurements on the resulting sample were carried out as described in Example 3A.

[0141] EXAMPLE 3C - CONDUCTING THE SAME RHEOMETER TEST ON POLYPROPYLENE WITHOUT ANY ORGANIC PEROXIDE

[0142] A control sample of virgin Profax® 6301 polypropylene powder with no added peroxide was also run on the Alpha Technologies RPA® 2000 rheometer using the same conditions as described in Example 3A.

[0143] FIGURE 3 shows the measured real viscosity q’ (Pa. sec) at 190°C versus ω frequency (Radians / sec) for all the of Examples 3A to 3C.

[0144] As shown in FIG. 3, using 600 ppm of the novel liquid peroxide composition of Example 1, the composition prepared in Example 3A unexpectedly provided a polypropylene polymer with a lower real viscosity q’ (Pa. sec) compared to polypropylene modified with 600 ppm Luperox® 101 BR, prepared in Example 3B. Comparing the resultsin Figure 3 the data indicates that it wouid be possible to use less of the peroxide composition taught in our invention provided in TABLE 2 of Example 1, ( i.e., less than 600 ppm) to achieve the same viscosity target that was obtained with 600 ppm of the commercial Luperox® 101BR product. As manufacturers of controlled rheology polypropylene desire to use less liquid organic peroxide in this process, the unexpected performance of novel liquid organic peroxide composition of Example 1 is clearly desirable as a more efficient peroxide for vis-breaking processes.

[0145] FIGURE 4 shows the elastic modulus properties of polypropylene at 190°C vis¬ broken using the organic peroxides of Examples 3A to 3B. Again Example 3C is the PP control with no peroxide. A lower elastic modulus is indicative of a lower molecular weight polymer, due to the vis-breaking process. As shown in FIG. 4, polypropylene modified with 600 ppm of the novel liquid organic composition of Example 1, unexpectedly, has a lower molecular weight (lower elastic modulus at 190°C) compared with the polypropylene modified using 600 ppm of Luperox® 101BR. The control PP with no peroxide (Example 3C) provided the highest elastic modulus at 190°C for PP. In summary, FIG. 4 confirms the unexpected desirable lower viscosity results of FIG. 3 for polypropylene modified with the novel liquid organic peroxide composition provided in Table 2 of Example 1.

[0146] EXAMPLE 4 - SECOND NOVEL LIQUID PEROXIDE COMPOSITION

[0147] A second novel liquid organic peroxide composition according to an embodiment of this application was prepared from the components listed in Table 4:

[0148] TABLE 4Organic Peroxide Amount of wt%Blend organic peroxide(grams)Vul-Cup® R 10.00 50.00%Luperox® DTA 10.00 50.00%Total organic 20.00peroxide

[0149] Specifically, 10.00 grams of solid, aromatic peroxide di(tert-butylperoxy)diisopropylbenzene (Vul-Cup® R) was added to a clear glass bottle containing 10.00 grams of aliphatic di-tert-amyl peroxide (Luperox® DTA) and a magnetic stir bar. The mixture of aromatic and aliphatic peroxides was stirred at ambient temperature for one hour by placing the clear glass bottle on a magnetic stir plate. The clear glass bottle was then stored for at least 48 hours at ambient temperatures. At the end of the storage time, a homogeneous, clear liquid peroxide composition was visually observed in the clear glass bottle. This homogenous liquid peroxide composition was kept in the same glass bottle for six months at ambient temperature and the composition in the clear glass bottle unexpectedly remained in the form of a homogeneous, clear liquid with no formation of solid crystals.

[0150] EXAMPLE 5A - CONTROLLED RHEOLOGY (VIS-BREAKING) OF POLYPROPYLENE USING NOVEL LIQUID ORGANIC COMPOSITION OF EXAMPLE4

[0151] The novel liquid organic peroxide composition of Example 4 was added to Profax® 6301 polypropylene granular powdered polymer at a concentration of 600 ppm (parts per million). Specifically, 0.0300g of the liquid peroxide composition of Example 4 was addedto 50.000g Profax®6301 polypropylene reactor granular powder and blended to a homogenous mixture using a bullet blender.

[0152] Using an Alpha Technologies RPA® 2000 rheometer, samples of polypropylene were subjected to a five (5) minute reaction at 190°C to fully decompose the organic peroxide. After the five-minute hold time at 190°C, the rheometer began a frequency sweep from 1 to 227 radians / sec using an applied strain of 20% or 0.0249 Radians.

[0153] EXAMPLE 5B - CONTROLLED RHEOLOGY (VIS-BREAKING) OF POLYPROPYLENE USING ALIPHATIC ORGANIC PEROXIDE

[0154] In this comparative example, 0.0300 g of liquid peroxide Luperox® DTA alone was added to 50.000 g of Profax® 6301 polypropylene granular powder and blended to a homogenous mixture using a bullet blender. The properties of the resulting sample were measured as described in Example 5A.

[0155] EXAMPLE 5C - CONDUCTING THE SAME RHEOMETER TEST ON POLYPROPYLENE WITHOUT ORGANIC PEROXIDE

[0156] A control sample of virgin Profax® 6301 polypropylene powder with no peroxide was also run on the Alpha Technologies RPA® 2000 rheometer using the same conditions as described in EXAMPLE 5A.

[0157] FIGURE 5 shows the measured real viscosity q’ (Pa. sec) at 190°C versus ω frequency (Radians / sec) for Examples 5A to 5C. The viscosity measurements in FIG. 5 show that 600 ppm of the novel peroxide of Example 4, unexpectedly, provided a modified polypropylene with a significantly lower viscosity than the viscosity of polypropylene modified with 600 ppm of Luperox® DTA.

[0158] FIGURE 6 shows the elastic modulus in Pascal (Pa) properties of modified polypropylene of Examples 5A to 5C at 190°C. A lower elastic modulus is indicative of a lower polymer molecular weight. Surprisingly, polypropylene modified with 600 ppm of the novel liquid peroxide composition of Example 4 resulted in a significantly lower elastic modulus, thus confirming the unexpected lower viscosity measurements shown in FIG.5, compared to the use of 600 ppm of the liquid Luperox® DTA.

[0159] As described in the embodiments and shown by the working and comparative examples described herein, an ambient liquid composition, preferably without solvents is required by the major PP producers. The novel ambient liquid homogeneous compositions of Tables 2 and 4, when used to conduct vis-breaking of PP, unexpectedly provided a lower viscosity PP polymer versus the corresponding singular use of the aliphatic dialkyl peroxide. The benefits to the PP producer is less peroxide required to produce a target viscosity or MFI while also producing less decomposition by-products due the lower peroxide concentration needed.

[0160] As shown by the working and comparative examples described herein, when used to crosslink an ethylene-propylene diene monomer (EPDM) polymer composition, the novel liquid peroxide blend described herein in Table 2, was used at a suitable concentration to provide an equivalent crosslink density to an EPDM polymer cured with only the solid di(tert-butylperoxy)diisopropylbenzene. Unexpectedly the cured EPDM elastomer article made with the novel peroxide formulation provided in Table 2, resulted in a crosslinked rubber article that exhibited no odor or bloom issues even after six months of storage at room temperature. On the other hand, the EPDM elastomer cross-linked with the singular use of the solid di(tert-butylperoxy)diisopropylbenzene exhibitedundesirable surface crystals (bloom) on the EPDM elastomer surface after one month or less.

[0161] As various modifications could be made in the above methods and compositions and would be apparent to those skilled in the art without departing from the scope of the invention, the disclosures herein are intended to be interpreted as illustrative and not limiting. Any numbers expressing quantities of ingredients, constituents, reaction conditions, and so forth used in the specification are to be interpreted as encompassing the exact numerical values identified herein, as well as being modified in all instances by the term “about” used as a term of approximation, and intended to include minor variations in the literally stated values as understood in the art and subject to any standard deviations found in their respective measurement techniques. None of the features recited herein should be interpreted as invoking 35 U. S. C. § 112, paragraph 6, unless the term “means” is explicitly used in reference to a function.

Claims

CLAIMSWhat is claimed is:

1. A liquid organic peroxide composition comprising:(a) di(tert-butylperoxy)diisopropylbenzene; and(b) at least one aliphatic organic peroxide selected from the group consisting of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, di(tert-amyl) peroxide, di(tert-butyl)peroxide, and 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3.wherein the organic peroxide composition is a homogenous liquid at ambient temperature.

2. The liquid organic peroxide composition of claim 1, wherein the at least one aliphatic organic peroxide is 2,5-dimethyl-2,5-di(t-butylperoxy)hexane.

3. The liquid organic peroxide composition of claim 1, wherein the at least one aliphatic organic peroxide is di-t-amyl peroxide.

4. The liquid organic peroxide composition of claim 1, wherein the at least one aliphatic organic peroxide is 2,5-dimethyl-2,5-di(t-butylperoxy)hexane and di-t-amyl peroxide.

5. The liquid organic peroxide composition of any one of claims 1 to 4, wherein a weight (wt%) ratio of the di(tert-butylperoxy)-diisopropylbenzene peroxide and the at least one aliphatic organic peroxide is from 20:80 to 80:20.

6. The liquid organic peroxide composition of any one of claims 1 to 5, wherein a weight (wt%) ratio of the di(tert-butylperoxy)-diisopropylbenzene peroxide and the at least one aliphatic organic peroxide is 42:58.

7. The liquid organic peroxide composition of any one of claims 1 to 5, wherein a weight (wt%) ratio of the di(tert-butylperoxy)-diisopropylbenzene peroxide and the at least one aliphatic organic peroxide is 50:50.

8. The liquid organic peroxide composition of any one of claims 1 to 7, further comprising a food-grade mineral oil.

9. The liquid organic peroxide composition of any one of claims 1 to 8, wherein the di(tert-butylperoxy)- diisopropylbenzene comprises a blend of meta- and para-isomers of the di(tert-butylperoxy)- diisopropylbenzene, and wherein the meta-isomer to the para-isomer weight (wt%) ratio is from 60:40 to 90:10.

10. The liquid organic peroxide composition of claim 9, wherein the meta-isomer to the para-isomer weight (wt%) ratio is 78:22.

11. A method of preparing a liquid organic peroxide composition, the method comprising: mixing di(tert-butylperoxy)diisopropylbenzene and at least one aliphatic organic peroxide selected from the group consisting of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, di(tert-amyl) peroxide, di(tert-butyl)peroxide, and 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3.

12. The method of claim 11, further comprising stirring the di(tert-butylperoxy)diisopropylbenzene and the at least one aliphatic organic peroxide for 72 hours at ambient temperature.

13. The method of claim 11, further comprising applying heat to melt the di(tert-butylperoxy)diisopropylbenzene prior to combining with stirring the di(tert- butylperoxy)diisopropylbenzene and the at least one aliphatic organic peroxide at ambient temperature.

14. The method of any one of claims 11-13, wherein the at least one aliphatic organic peroxide is 2,5-dimethyl-2,5-di(t-butylperoxy)hexane.

15. The method of any one of claims 11-14, wherein the at least one aliphatic organic peroxide is di-t-amyl peroxide.

16. The method of any one of claims 11-15, wherein the at least one aliphatic organic peroxide is 2,5-dimethyl-2,5-di(t-butylperoxy)hexane and di-t-amyl peroxide.

17. The method of any one of claims 11-16, wherein a weight (wt%) ratio of the di(tert-butylperoxy)-diisopropylbenzene peroxide and the at least one aliphatic organic peroxide is from 20:80 to 80:20.

18. The method of any one of claims 1 to 17, wherein a weight (wt%) ratio of the di(tert-butylperoxy)-diisopropylbenzene peroxide and the at least one aliphatic organic peroxide is 42:58.

19. The method of any one of claims 1 to 17, wherein a weight (wt%) ratio of the di(tert-butylperoxy)-diisopropylbenzene peroxide and the at least one aliphatic organic peroxide is 50:50.

20. The method of any one of claims 1 to 19, further comprising adding a food-grade mineral oil to the liquid organic peroxide composition.

21. The method of claims 1 to 20, wherein the di(tert-butylperoxy)-diisopropylbenzene comprises a blend of meta- and para-isomers of the di(tert-butylperoxy)- diisopropylbenzene, and wherein the meta-isomer to the para-isomer weight (wt%) ratio is from 60:40 to 90:10.

22. The method of claim 21, wherein the meta-isomer to the para-isomer weight (wt%) ratio is 78:22.

23. The method of any of claims 1 -22, further comprising melting the di(tert-butylperoxy)diisopropylbenzene and adding molten di(tert-butylperoxy)diisopropylbenzene to at least one ambient temperature aliphatic organic peroxide with stirring to instantaneously produce a peroxide composition that remains a homogeneous liquid at ambient temperatures.

24. A method of controlling rheology of a polymer, the method comprising:blending a liquid organic peroxide composition with a polymer to form a homogenous mixture; andsubjecting the homogenous mixture to a vis-breaking process,wherein the liquid organic peroxide composition comprises di(tert-butylperoxy)diisopropylbenzene; and at least one aliphatic organic peroxide selected from the group consisting of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, di(tert-amyl) peroxide, di(tert-butyl)peroxide, and 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, and wherein the organic peroxide composition is a homogenous liquid at ambient temperature.

25. A method of cross-linking a polymer, the method comprising:mixing a liquid organic peroxide composition and a polymer; andcuring using a time-temperature profile such that at least 95 wt% or more of the peroxide is decomposed during the process;wherein the liquid organic peroxide composition comprises di(tert- butylperoxy)diisopropylbenzene; and at least one aliphatic organic peroxide selectedfrom the group consisting of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, di(tert-amyl) peroxide, di(tert-butyl)peroxide, and 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, and wherein the organic peroxide composition is a homogenous liquid at ambient temperature.

26. The method of claim 24 or 25, wherein the polymer is selected from the group consisting of polypropylene, polyethylene, polyamide, polylactic acid, polyhydroxyalkanoates, polyhydroxybutyrate, ethylene-vinyl acetate, ethylene-propylene rubbers, terpolymers nitrile butadiene rubber, hydrogenated nitrile butadiene rubber, fluorocarbon-based fluoroelastomers, and silicone rubbers.

27. The method of any one of claims 24-26, wherein the at least one aliphatic organic peroxide is 2,5-dimethyl-2,5-di(t-butylperoxy)hexane.

28. The method of any one of claims 24-27, wherein the at least one aliphatic organic peroxide is di-t-amyl peroxide.

29. The method of any one of claims 24-28, wherein the at least one aliphatic organic peroxide is 2,5-dimethyl-2,5-di(t-butylperoxy)hexane and di-t-amyl peroxide.

30. The method of any one of claims 24-29, wherein a weight (wt%) ratio of the di(tert-butylperoxy)-diisopropylbenzene peroxide and the at least one aliphatic organic peroxide is from 20:80 to 80:20.

31. The method of any one of claims 24-30, wherein a weight (wt%) ratio of the di(tert-butylperoxy)-diisopropylbenzene peroxide and the at least one aliphatic organic peroxide is 42:58.

32. The method of any one of claims 24-31, wherein a weight (wt%) ratio of the di(tert-butylperoxy)-diisopropylbenzene peroxide and the at least one aliphatic organic peroxide is 50:50.

33. The method of any one of claims 24-32, wherein the di(tert-butylperoxy)-diisopropylbenzene comprises a blend of meta- and para-isomers of the di(tert-butylperoxy)- diisopropylbenzene, and wherein the meta-isomer to the para-isomer weight (wt%) ratio is from 60:40 to 90:10.

34. The method of any one of claims 24-33, wherein the meta-isomer to the paraisomer weight (wt%) ratio is 78:22.

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