Encapsulation of organic peroxides with polyurea shells

Abstract

Encapsulated liquid organic peroxide particles with a polyurea shell can be used in a variety of applications. A method of encapsulating a liquid organic peroxide comprising a polymerization reaction between an aqueous mixture of amines and an organic solution comprising at least one isocyanate.

Description

Technical Field

[0001] The present invention relates to encapsulated liquid peroxide particles encapsulated with a polyurea shell, and products made using these encapsulated liquid peroxide particles. The present disclosure also relates to a method of encapsulating an organic liquid peroxide with a polyurea shell. Background Art

[0002] Organic peroxides ("OPs") are used in a variety of applications including, for example, polymer initiation, polymer modification, rubber crosslinking, and composite curing. Examples of organic peroxide applications include the production of polymers such as styrene, visbreaking of polypropylene, and crosslinking in rubbers used in automobiles, composite boat hulls, truck bodies, and pultruded articles. Free radicals are generated by the natural thermal degradation of OPs at a given temperature or by chemical promotion. The degradation of OPs to free radicals generates heat and byproducts that can be problematic if not controlled. Encapsulation offers several advantages to the use of organic peroxides.

[0003] For example, encapsulation of liquid organic peroxide can change its form into solid state, thereby improves operability and / or safety in some applications. Encapsulation of organic peroxide can protect it from the influence of other components in the formulation, thereby improves the stability of the formulation and / or provides on-demand solidification by controlling the release of the encapsulated material. This potentially allows the use of a promotion system in previously unreachable applications (such as pultrusion or polymer initiation), thereby reducing the demand for more dangerous low-temperature storage peroxides. Encapsulation can also protect organic peroxide from increasing unintentionally because of pollution.

[0004] Several techniques have been used or proposed to encapsulate peroxides, one of which is the deposition of an encapsulating film by coacervation. Other processes involve polymerizing substances contained in droplets or in a surrounding continuous liquid phase, so that the resulting polymer (from the droplets or liquid phase) is deposited on the surface of these droplets. Yet another method involves projecting droplets through a falling film of liquid capsule wall material, which then solidifies around the individual droplets.

[0005] WO0015694A2 describes the use of encapsulated organic peroxides for curing resins. Although the organic peroxides described include solid and liquid organic peroxides, the encapsulation process disclosed therein mainly focuses on adsorbing the organic peroxide onto a substrate using an almond shell encapsulation method or using ultrasonic encapsulation.

[0006] U.S. Patent 3,577,515 describes methods and techniques for preparing crosslinked microcapsule walls in which compounds such as diacyl chlorides, bischloroformates, disulfonyl chlorides, polyacyl chlorides, polychloroformates, diisocyanates, polyisocyanates, polysulfonyl chlorides, phosgene, or other organic intermediates are encapsulated by interfacial condensation. The encapsulation process is used to encapsulate liquid organic peroxides using sebacyl chloride.

[0007] US Patent No. 4,102,800 relates to alkylated phenol sulfides contained in microcapsules wherein the capsule wall is a cross-linked polyamide, polyurea or polyamide-polyurea resin.

[0008] U.S. Publication No. 2019 / 060245 describes a method for encapsulating solid organic peroxides that involves forming micelles of sodium or potassium fatty acid salts around solid peroxide particles.

[0009] Therefore, there is still a need for an effective, simple, practical, convenient and easy-to-control method for encapsulating liquid organic peroxides. Summary of the Invention

[0010]

[0014] Embodiments of the present disclosure relate to encapsulated liquid organic peroxide particles encapsulated with a polyurea shell, methods of encapsulating liquid organic peroxides with a polyurea shell, and compositions or materials made from or using these encapsulated liquid organic peroxides.

[0011] The encapsulated liquid organic peroxide particles may comprise, consist essentially of, or consist of a liquid organic peroxide encapsulated by a polyurea shell, wherein the liquid organic peroxide accounts for about 70% to about 95% by weight of the total weight of the encapsulated liquid organic peroxide (i.e., the total weight of the encapsulating shell and the liquid organic peroxide therein). The resulting encapsulated liquid organic peroxide particles may be in the form of an emulsion, or in the form of solid particles, including, for example, a free-flowing powder.

[0012] In some embodiments, the encapsulated liquid organic peroxide particles may include a desiccant, such as silicon dioxide or the like.

[0013] In some embodiments, the encapsulated liquid organic peroxide particles include one or more surfactants, such as polyvinyl pyrrolidone, polyvinyl alcohol, combinations thereof, and the like.

[0014] In some embodiments, the encapsulated liquid organic peroxide particles comprise a liquid organic peroxide encapsulated by a polyurea shell, wherein the polyurea shell is formed from polymerization between a preformed aqueous mixture of an amine and an organic solution comprising at least one isocyanate.

[0015] Encapsulated liquid peroxide particles may be prepared by polymerization, the method comprising the following steps:

[0016] - preparing an organic phase solution comprising at least one isocyanate dispersed in a liquid organic peroxide,

[0017] - preparing an aqueous phase solution comprising at least one surfactant,

[0018] - mixing the organic phase solution with the aqueous phase solution to form an emulsion,

[0019] - adding an aqueous solution comprising at least one amine, preferably in the form of a mixture of two amines, to the emulsion to initiate polymerization,

[0020] - mixing the aqueous solution and the emulsion for a period of time until a solution comprising encapsulated liquid peroxide particles is produced,

[0021] - separating, and optionally drying, the encapsulated liquid peroxide particles to form solid particles, preferably comprising less than 10% moisture and / or organic solvent, or less than 5% moisture and / or organic solvent, or less than 2% moisture and / or organic solvent, or less than 1% moisture and / or organic solvent, or less than 0.5% moisture and / or organic solvent.

[0022] Encapsulated liquid organic peroxide particles can be used to prepare compositions or products that can be used for rubber and / or elastomer crosslinking, polymer initiation, rheology control, scorch reduction, composites (e.g., polyester resins), and 3D printing applications. For example, encapsulated liquid organic peroxide particles can be used as crosslinking agents for silicone, EPDM, polyethylene, chlorinated polyethylene, fluoroelastomers, etc., and can improve cure retention over time compared to pure (i.e., unencapsulated) organic peroxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] This figure depicts one embodiment of the synthesis of the encapsulated liquid organic peroxides of the present invention. DETAILED DESCRIPTION

[0024] One aspect of the present disclosure relates to packaged liquid organic peroxide particles comprising a liquid peroxide encapsulated by a polyurea shell, and optionally a desiccant. In one embodiment, the liquid organic peroxide comprises from about 70 wt % to about 95 wt % of the total weight of the packaged liquid organic peroxide particles.

[0025] The encapsulated liquid organic peroxide particles may have a core-shell structure, wherein the liquid organic peroxide particles provide a core at least partially or completely surrounded by a polyurea shell.

[0026] The liquid organic peroxide encapsulated by the polyurea shell includes any liquid organic peroxide, including but not limited to, those belonging to or selected from the following groups: aliphatic and aromatic diacyl peroxides, dialkyl peroxides, peroxyketal peroxides, peroxyesters, monoperoxycarbonates, peroxydicarbonates, and hydroperoxides, and / or combinations / mixtures thereof; preferably, those that are liquid at room temperature (i.e., liquid at 25°C), including mixtures thereof. Preferred are the peroxydicarbonate, perester, dialkyl, and hydroperoxide groups, with peroxydicarbonates and peresters being more preferred. Examples of diacyl peroxides include decanoyl peroxide, myristoyl peroxide, di-(3,5,5-trimethylhexanoyl) peroxide, o-methylbenzoyl peroxide, o-methoxybenzoyl peroxide, o-ethoxybenzoyl peroxide, o-chlorobenzoyl peroxide, and 2,4-dichlorobenzoyl peroxide. Examples of dialkyl peroxides include di(tert-butyl) peroxide and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane. Examples of peroxyketals include 1,1-di(tert-amylperoxy)-cyclohexane, 1,1-di(tert-butylperoxy)-cyclohexane, and 1,1-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane. Examples of peroxyesters include tert-butyl peroxypivalate, tert-butyl peroxyneodecanoate, tert-butyl peroxy-2-ethylhexanoate, tert-amyl peroxy-2-ethylhexanoate, tert-amyl peroxypivalate, and tert-butyl peroxybenzoate. Examples of monoperoxycarbonates include: 0-0-(tert-butyl)O-(2-ethylhexyl)monoperoxycarbonate and 0-0-(tert-amyl)O-(2-ethylhexyl)monoperoxycarbonate. Examples of hydroperoxides include tert-butyl hydroperoxide, tert-amyl hydroperoxide, and cumene hydroperoxide. Examples of peroxydicarbonates include di(sec-butyl) peroxydicarbonate, di(2-ethylhexyl) peroxydicarbonate, and di(n-propyl) peroxydicarbonate.

[0027] In exemplary embodiments, the liquid organic peroxide can be combined with other organic peroxides that are solid at room temperature. In exemplary embodiments, the liquid organic peroxide particles include at least 1%, 2%, 5%, 10%, 15%, 20%, 25%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or up to 99% by weight of other organic peroxides that are solid at room temperature, and mixtures thereof.

[0028] In exemplary embodiments, the liquid organic peroxide particles include less than 50%, 40%, 30%, 20%, 10%, 5%, 2%, or 1% by weight of other organic peroxides that are solid at room temperature, and mixtures thereof.

[0029] In an exemplary embodiment, the encapsulated liquid organic peroxide particles are free of ketone peroxide, benzoyl peroxide, dodecyl peroxide, t-butylperoxymalic acid, and / or combinations thereof. In an exemplary embodiment, the liquid organic peroxide particles comprise less than 50%, 40%, 30%, 20%, 10%, 5%, 2%, or 1% by weight of ketone peroxide, benzoyl peroxide, dodecyl peroxide, t-butylperoxymalic acid, and / or combinations / mixtures thereof.

[0030] In some embodiments, the liquid organic peroxide is selected from the group consisting of tert-butyl peroxybenzoate, 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, and / or combinations / mixtures thereof, including, for example, tert-butylperoxy-3,3,5-trimethylcyclohexane available from Arkema. P. 101. 231 and / or combinations / mixtures thereof.

[0031] As used herein, "liquid" refers to a substance that flows and has a measurable volume but no shape.

[0032] As used herein, "liquid organic peroxide" refers to an organic peroxide, an organic peroxide solution, or a blend of two or more organic peroxides that is liquid within a temperature range of 20°C to 60°C.

[0033] As used herein, "polyurea" refers to a compound / moiety formed by the reaction of an isocyanate with an amine or amine-containing reactant. Preferably, the amine is a single amine or a mixture of two or more different amines or amine-containing reactants. Each amine can be unfunctionalized, monofunctionalized, difunctionalized, or multifunctionalized. In some embodiments, two amines allow for flexibility in the amount of crosslinking in the wall.

[0034] Without being bound by any theory, the polyurea shell encapsulating the liquid organic peroxide particles can be formed by interfacial polymerization between an amine and at least one isocyanate. According to a specific embodiment, this process occurs in a "single encapsulation" format, wherein the organic peroxide and other optional ingredients are contained within a single polyurea shell. Alternatively, the product can be the result of continuous encapsulation, wherein multi-layered shell particles can be formed.

[0035] Amines and ammonia-containing reactants can be aliphatic or aromatic, and have primary and / or secondary amine functional groups. Examples of suitable amines include one, two, or more of the following: diethylenetriamine (DETA), ethylenediamine (EDA), diethyltoluenediamine, dimethylthiotoluenediamine, NN'-di(sec-butyl)aminodiphenylmethane, or combinations thereof. In a preferred embodiment, the amine is a single amine or a mixture of two or more amines.

[0036] In some embodiments, the amine is diethylenetriamine (DETA) or ethylenediamine (EDA) or a mixture of DETA and EDA.

[0037] The mixture of amines may comprise at least two different amines in a molar ratio of 50 / 50, 40 / 60, 30 / 70, 20 / 80, 10 / 90, 60 / 40, 70 / 30, 80 / 20, 90 / 10, or any molar ratio between 10 / 90 and 90 / 10.

[0038] In some embodiments, the amine comprises a mixture of DETA and EDA in a molar ratio of 50 / 50, 40 / 60, 30 / 70, 20 / 80, 10 / 90, 60 / 40, 70 / 30, 80 / 20, 90 / 10, or any molar ratio between 10 / 90 and 90 / 10. Increasing the amount of amine, such as DETA, can increase the amount of crosslinking. By fine-tuning the level of crosslinking, the mechanical properties of the shell can be optimized, including, for example, controlling the release characteristics of the encapsulated liquid organic peroxide.

[0039] Based on the solubility in the organic phase, isocyanate can be selected from aliphatic, cyclic and / or aromatic classes and combinations / mixtures thereof. Preferably, isocyanate is compatible / suitable in the liquid phase. Suitable isocyanates include hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), methylene dicyclohexyl diisocyanate, hydrogenated MDI and / or its combination. In some embodiments, the polyurea shell can be formed by at least one isocyanate selected from methylene diphenyl diisocyanate (MDI), poly (hexamethylene diisocyanate) (HMDI), isophorone diisocyanate (IPDI)) and / or its combination. Suitable isocyanate can also be bio-based isocyanate and / or isocyanate with high renewable content, including, for example, L-lysine diisocyanate ethyl ester (LLDI) and L-lysine triisocyanate ethyl ester (LLTI) etc.

[0040] In some embodiments, at least one isocyanate is dispersed in an organic phase solution comprising a liquid organic peroxide. Preferably, the solubility of the isocyanate is such that the isocyanate is substantially or completely dissolved in the organic peroxide prior to the encapsulation process. In some embodiments, the solubility of the at least one isocyanate in the liquid organic peroxide phase solution is from about 0.08 wt % to about 100 wt %.

[0041] %, or preferably about 20 wt % to 100 wt %, or more preferably about 50 wt % to about 100 wt %.

[0042] %, or from about 60 weight % to about 100 weight %, or from about 70 weight % to about 100 weight %.

[0043] In some embodiments, the encapsulated liquid organic peroxide particles have a wall thickness of about 0.1 to about 50%, about 1 to about 20%, about 2 to about 10%, based on the amount of amine and isocyanate relative to the organic peroxide loading. In other embodiments, the encapsulated liquid organic peroxide particles have a wall thickness greater than about 50%, based on the amount of amine and isocyanate relative to the organic peroxide loading. The wall thickness is related to the ratio of the weight of amine and isocyanate to the total weight of amine, isocyanate and peroxide, and the calculation assumes that the crosslinking rate of the isocyanate is 100%. Table 1 provides the wall thickness for preparing a 5% wall thickness encapsulated liquid organic peroxide particle. Exemplary formulations of P.

[0044] Table 1: Preparation of packaging Exemplary formulation of P (5% wall thickness)

[0045]

[0046] The following describes the formula used to calculate the wall thickness for the formulations listed in Table 1:

[0047]

[0048] Compared to the theoretical ratio of amine and isocyanate, an excess of amine, for example 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, up to 100% by weight, can be added to the amine mixture to increase the reaction rate and encapsulation formation.

[0049] The average particle size of the encapsulated liquid organic peroxide particles in the emulsion is from about 1 to about 150 μm, or from about 5 to about 100 μm, or from about 10 to about 50 μm, as measured using a Malvern Mastersizer 3000E particle size analyzer (laser light scattering).

[0050] In some embodiments, the encapsulated liquid organic peroxide particles comprise from about 60 wt % to about 95 wt %, preferably from about 70 wt % to about 95 wt %, more preferably from about 80 wt % to about 95 wt %.

[0051] %, or most preferably from about 90 wt % to about 95 wt %, or more wt % of the liquid organic peroxide.

[0052] In some embodiments, the encapsulated liquid organic peroxide particles are in an emulsion. In some embodiments, the encapsulated liquid organic peroxide particles are solid, preferably powder, and optionally contain at least one or more desiccant. Examples of desiccant include silicon dioxide, calcium chloride (CaCl ), sodium sulfate (Na 2 SO 4 ), calcium sulfate [CaSO 4 , also known as Drierite] and / or magnesium sulfate (MgSO 4 ), wherein silicon dioxide is preferred. In some embodiments, the encapsulated liquid organic peroxide particles comprise one or more additives selected from the group consisting of desiccant, silicon dioxide, xanthan gum, biocide, preservative, process oil, processing aid, pigment, dye, tackifier, wax, reinforcing aid, UV stabilizer, stabilizer, foaming agent, scorch retardant, activator, antiozonant and auxiliary agent.

[0053] Another aspect of the present disclosure relates to a method for producing encapsulated liquid peroxide particles by polymerization, comprising the steps of:

[0054] - preparing an organic phase solution comprising at least one isocyanate dispersed in a liquid organic peroxide,

[0055] - preparing an aqueous phase solution comprising at least one surfactant,

[0056] - mixing the organic phase solution with the aqueous phase solution to form an emulsion,

[0057] - adding an aqueous solution comprising at least one amine to the emulsion,

[0058] - mixing the aqueous solution and the emulsion for a period of time until a solution comprising encapsulated liquid peroxide particles is produced,

[0059] - Separating and optionally drying the encapsulated liquid peroxide particles to form solid particles. One embodiment of the process is depicted in the figure.

[0060] In some embodiments, the aqueous phase solution includes one or more surfactants. The surfactant can be any surfactant or combination of surfactants that can impart the desired stability and particle size distribution to the emulsion. Suitable surfactants include those selected from the group consisting of anionic surfactants, nonionic surfactants, amphoteric surfactants, polymeric surfactants, and combinations thereof. Examples of anionic surfactants include ammonium lauryl sulfate, sodium lauryl sarcosinate, sodium stearate, sodium lauryl sulfate, and ammonium laureth sulfate. Examples of nonionic surfactants include ethoxylated alcohols, ethoxylated fatty acids, and alkoxylated fatty acids. Examples of amphoteric surfactants include alkylamidopropylamine N-oxide, alkyldimethylamine N-oxide, alkyl betaines, and alkylamidopropyl betaines. Examples of polymeric surfactants include 2-acrylamido-2-methyl-1-propanesulfonic acid and alkyl methacrylamide, alkyl methacrylate or alkyl acrylate, polyvinyl pyrrolidone, and polyvinyl alcohol.

[0061] In some embodiments, the at least one surfactant is selected from polyvinyl pyrrolidone, polyvinyl alcohol, and combinations thereof.

[0062] In other embodiments, at least one surfactant is added to the aqueous phase. A surfactant or combination of surfactants can be added until a concentration of 1 g / L to 15 g / L, or 3 g / L to 12 g / L, or 5 g / L to 10 g / L is reached.

[0063] In some embodiments, an aqueous solution containing an amine is produced during the preparation of the organic phase solution and the aqueous phase solution. Without being bound by any particular theory, it is believed that premixing the amine in an aqueous solution before introducing it into the emulsion can remove potential exotherms that could negatively impact the encapsulation process or the thermal stability of the organic peroxide.

[0064] In some embodiments, the amine is a mixture of two or more amines. In these mixtures, the molar ratio of the two different amines can be 50 / 50, 40 / 60, 30 / 70, 20 / 80, 10 / 90, 60 / 40, 70 / 30, 80 / 20, 90 / 10, or any molar ratio between 10 / 90 and 90 / 10. In some embodiments, the two different amines are DETA and EDA.

[0065] In some embodiments, at least one isocyanate is selected from hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), methylene dicyclohexyl diisocyanate, hydrogenated MDI, and combinations thereof. The isocyanate may also be selected from bio-based isocyanates, including, for example, L-lysine ethyl diisocyanate (LLDI) and L-lysine ethyl triisocyanate (LLTI).

[0066] In other embodiments, preparing the organic phase solution further comprises mixing the at least one isocyanate with the liquid organic peroxide for 1 minute to 1 hour, or 5 minutes to 40 minutes, or for a predetermined period of time.

[0067] In some embodiments, the organic phase and the aqueous phase are mixed in an intermittent or continuous manner to form an emulsion. In some embodiments, the organic phase and the aqueous phase are mixed in a continuous or intermittent manner for 1 second to 10 minutes, preferably 5 seconds to 5 minutes, or more preferably 10 seconds to 3 minutes to form an emulsion.

[0068] In other embodiments, the aqueous solution and the emulsion are mixed for 5 minutes to 5 hours, or 10 minutes to 4.5 hours, or 30 minutes to 4 hours, or 30 minutes to 3 hours, or 1 hour to 3 hours, or a predetermined time based on pH testing to produce encapsulated liquid peroxide particles.

[0069] In some embodiments, the pH of the aqueous solution (i.e., the emulsion mixture) is monitored to determine when the reaction and mixing process should be stopped. The chemical reaction occurring in the emulsion mixture can be stopped by adding an acid (e.g., hydrochloric acid) to the mixture. The reaction will stop when the amine in the mixture is neutralized by the acid to a pH of about 7.

[0070] The encapsulated liquid organic peroxide particles can be used in various applications in the form of emulsions or solid powders. Suitable additional additives for the encapsulated liquid peroxide particles include surfactants, carriers, bleach activators, builders, abrasives, pigments, rheology control agents, gelling agents, perfumes, anti-deposition agents, enzymes, etc.

[0071] If the encapsulated liquid organic peroxide particles are used as an emulsion in subsequent applications, various additives, including but not limited to xanthan gum and biocides, can be incorporated into the resulting aqueous solution and emulsion mixtures to enhance their long-term physical stability and other properties.

[0072] If the encapsulated liquid peroxide particles are to be used as a powder, the particles are separated from the resulting aqueous solution and emulsion mixture by a phase separation process, wherein the encapsulated organic phase is recovered and the aqueous phase is removed. The encapsulated liquid organic peroxide particles may be further processed such that the encapsulated liquid peroxide particles contain less than 10% moisture and / or organic solvent, or less than 5% moisture and / or organic solvent, or less than 2% moisture and / or organic solvent, or less than 1% moisture and / or organic solvent.

[0073] To further improve the separation and drying process, additives such as silica (eg Hi-SIL233), xanthan gum and / or biocides can be incorporated into the separated encapsulated organic phase.

[0074] Encapsulated liquid organic peroxide particles can be used as curing powders, polymer modifiers, crosslinkers, composite initiators, and in 3D printing ink applications.

[0075] Other embodiments of the present invention relate to a masterbatch or ready-to-cure composition comprising at least one encapsulated organic peroxide as described herein and at least one elastomer to produce a peroxide-elastomer composition. The at least one elastomer can be selected from the group consisting of silicone, EPDM, polyethylene, chlorinated polyethylene, and fluoroelastomers. The peroxide-elastomer composition of the present invention can be prepared by mixing at least one encapsulated peroxide into at least one elastomer. The peroxide-elastomer composition of the present invention can then be cured to form articles such as hoses, gaskets, seals, wire and cable, O-rings, shock absorbers, and / or crosslinked films.

[0076] Various aspects of the invention

[0077] Aspect 1. A packaged liquid organic peroxide particle comprising:

[0078] a liquid organic peroxide encapsulated by a polyurea shell, wherein the liquid organic peroxide comprises from about 60 weight percent to about 95 weight percent of the total weight of the encapsulated liquid organic peroxide particles;

[0079] and optionally a desiccant.

[0080] Aspect 2. The encapsulated liquid organic peroxide particles of aspect 1, wherein the liquid organic peroxide is selected from the group consisting of diacyl peroxides, dialkyl peroxides, peroxyketal peroxides, peroxydicarbonate peroxides, peroxyesters, monoperoxycarbonate peroxides, hydroperoxides, and mixtures thereof.

[0081] Aspect 3. The packaged liquid organic peroxide particles of any one of Aspects 1 or 2, wherein the liquid organic peroxide is selected from the group consisting of tert-butyl peroxybenzoate, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-di(tert-butylperoxy)cyclohexane, OO-(tert-butyl)O-(2-ethylhexyl)monoperoxycarbonate, and mixtures thereof.

[0082] Aspect 4. Encapsulated liquid organic peroxide particles according to any one of aspects 1 to 3, wherein the polyurea shell is polymerized from an amine, an amine mixture or an amine-containing reactant and a liquid organic solution comprising at least one isocyanate; preferably, the at least one isocyanate is selected from the group consisting of aliphatic isocyanates, cyclic isocyanates and / or aromatic isocyanates, and combinations thereof; more preferably, the at least one isocyanate is selected from the group consisting of hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), methylene dicyclohexyl diisocyanate, hydrogenated MDI, and combinations thereof.

[0083] Aspect 5. The packaged liquid organic peroxide particles according to aspect 4, wherein the amine mixture comprises two or more amines or amine-containing reactants, preferably diethylenetriamine (DETA) and ethylenediamine (EDA), more preferably the molar ratio of DETA to EDA is 10 / 90 to 90 / 10.

[0084] Aspect 6. The packaged liquid organic peroxide particles of Aspect 4, wherein the at least one isocyanate has a solubility in the liquid organic solution of about 0.08 wt % to 100 wt %, preferably about 20 wt % to 100 wt %, more preferably about 50 wt % to about 100 wt %.

[0085] Aspect 7. The encapsulated liquid organic peroxide particle of any one of aspects 4-6, wherein the thickness of the polyurea shell ranges from about 0.1 to 50% based on the amount of amine and isocyanate relative to the total amount of amine, isocyanate and organic liquid peroxide.

[0086] Aspect 8. The packaged liquid organic peroxide particles according to any one of aspects 1 to 7, wherein the packaged liquid organic peroxide particles have a particle size ranging from about 1 to 150 μm.

[0087] Aspect 9. The packaged liquid organic peroxide particles according to any one of aspects 1 to 8, wherein the liquid organic peroxide accounts for about 70% to about 95% by weight, preferably about 80% to about 95% by weight, and more preferably about 90% to 95% by weight of the total weight of the packaged liquid organic peroxide particles.

[0088] Aspect 10. The packaged liquid organic peroxide particles according to any one of aspects 1 to 9, wherein the packaged liquid organic peroxide particles are solid, preferably powder, and optionally contain one or more of a desiccant, preferably silica, xanthan gum, a biocide, and an additive.

[0089] Aspect 11. An encapsulated liquid organic peroxide particle comprising a liquid organic peroxide encapsulated by a polyurea shell, wherein the polyurea shell is formed by polymerization between an aqueous solution of a preformed amine and an organic solution comprising at least one isocyanate.

[0090] Aspect 12. A method for producing encapsulated liquid peroxide particles by polymerization, comprising the steps of:

[0091] - preparing an organic phase solution comprising at least one isocyanate dispersed in a liquid organic peroxide,

[0092] - preparing an aqueous phase solution comprising at least one surfactant,

[0093] - mixing the organic phase solution with the aqueous phase solution to form an emulsion,

[0094] - adding an aqueous solution comprising at least one amine to the emulsion,

[0095] - mixing the aqueous solution and the emulsion for a period of time until a solution comprising encapsulated liquid peroxide particles is produced, and

[0096] - Isolating and optionally drying the encapsulated liquid peroxide particles.

[0097] Aspect 13. The method of aspect 12, wherein the at least one surfactant is selected from the group consisting of polyvinyl pyrrolidone, polyvinyl alcohol, and combinations thereof, and the aqueous solution of amines comprises a mixture of at least two different amines.

[0098] Aspect 14. The method of aspect 12, wherein the encapsulated liquid peroxide particles are separated from a solution containing the particles by a phase separation process, wherein the phase separation process recovers an organic phase containing the encapsulated liquid peroxide particles.

[0099] Aspect 15. The method of aspect 12, wherein the liquid organic peroxide is one or more liquid organic peroxides selected from the group consisting of diacyl peroxides, dialkyl peroxides, peroxyketal peroxides, peroxydicarbonate peroxides, monoperoxycarbonate peroxides, peroxyesters, hydroperoxides, tert-butyl peroxybenzoate, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-di(tert-butylperoxy)cyclohexane, O-O-(tert-butyl)O-(2-ethylhexyl)monoperoxycarbonate, and combinations thereof.

[0100] Aspect 16. The method of aspect 12, wherein the amine is diethylenetriamine (DETA), ethylenediamine (EDA), or a combination thereof, preferably wherein the molar ratio of DETA to EDA in the mixture of amines is 10 / 90 to 90 / 10.

[0101] Aspect 17. The method of aspect 12, wherein the at least one isocyanate is selected from the group consisting of aliphatic isocyanates, cyclic isocyanates, aromatic isocyanates, methylene diphenyl diisocyanate (MDI), poly(hexamethylene diisocyanate) (HMDI), and combinations thereof.

[0102] Aspect 18. The packaged liquid organic peroxide particles according to any one of aspects 1 to 11, wherein the packaged liquid organic peroxide particles are solid, the solid containing less than 10% water and / or organic solvent, preferably less than 5% water and / or organic solvent, and more preferably less than 2% water and / or organic solvent, based on the total weight of the packaged organic peroxide particles.

[0103] Aspect 19. An emulsion comprising the encapsulated liquid organic peroxide particles of any of aspects 1-11.

[0104] Aspect 20. A masterbatch or ready-to-cure composition comprising at least one encapsulated organic peroxide according to any of aspects 1-11 and at least one elastomer.

[0105] Aspect 21. The masterbatch or ready-to-cure composition of Aspect 20, wherein the at least one elastomer is at least one of silicone, EPDM, polyethylene, chlorinated polyethylene, and a fluoroelastomer.

[0106] Aspect 22. A composition comprising at least one encapsulated organic peroxide according to any one of aspects 1 to 11, at least one liquid polyester resin, and optionally fillers and / or fiber reinforcements.

[0107] Aspect 23. The composition of Aspect 22, which is cured using pultrusion, compression molding, mass molding, and / or potting to form a cross-linked composite.

[0108] Example

[0109] Example 1: Microencapsulation of P

[0110] 100g P and 4.24g Rubinate M isocyanate was mixed. The mixture of organic peroxide and isocyanate was then added to 386 g of a 4 g / L aqueous solution of polyvinyl alcohol (PVA). The combined solution was emulsified using a rotor-stator apparatus. 3.23 g of diethylenetriamine (DETA) and 1.91 g of ethylenediamine (EDA) were diluted in 34.7 g of water. Once a stable emulsion was obtained, the amine diluted in water was added to the emulsion and stirred at room temperature for 1 hour. The final solution was phase separated and the organic phase was separated, dried at room temperature and sieved with Hi-SIL 233 silica to obtain a cross-linked polyurea shell encapsulated in the shell. Yellow powder. The particle size range is 10 to 30 microns.

[0111] Example 2: Microencapsulation of 101

[0112] 100g 101 was mixed with 4.84 g of poly(hexamethylene diisocyanate). The mixture of organic peroxide and isocyanate was then added to 470 g of a 4 g / L aqueous solution of PVA. The combined solution was emulsified using a rotor-stator apparatus. 2.52 g of diethylenetriamine (DETA) and 1.47 g of ethylenediamine (EDA) were placed in 26.6 g of water. Once a stable emulsion was obtained, the amine diluted in water was added to the emulsion and stirred at room temperature for 3 hours. The final solution was phase separated and the encapsulated organic phase was separated, dried at room temperature, and sieved with Hi-SIL 233 silica to obtain a cross-linked polyurea wall encapsulated in the polyurea. 101 Yellow powder. Particle size range is 10 to 50 microns.

[0113] Example 3: Microencapsulation of 231

[0114] 150g 101 was mixed with 3.78 g of poly(hexamethylene diisocyanate). The mixture of organic peroxide and isocyanate was then added to 428 g of a 4 g / L aqueous solution of PVA. The combined solution was emulsified using a rotor-stator apparatus. 3.78 g of diethylenetriamine (DETA) and 2.2 g of ethylenediamine (EDA) were placed in 40 g of water. Once a stable emulsion was obtained, the amine diluted in water was added to the emulsion and stirred at room temperature for 3 hours. The final solution was phase separated and the encapsulated organic phase was separated, dried at room temperature, and sieved with Hi-SIL 233 silica to obtain a cross-linked polyurea wall encapsulated in the polyurea. 231 Yellow powder. Particle size range is 30 to 100 microns.

[0115] Example 4: Determination of the amount of encapsulated liquid organic peroxide by solvent extraction

[0116] About 100mg contains Encapsulated powders with a wall thickness of 5% or 20% P were placed in a 25 mL volumetric flask and an extraction solvent (methanol, isopropanol, or acetonitrile) was added. The samples were saturated in the extraction solvent for one hour and then aliquots were analyzed by HPLC. The role of the solvent is to penetrate / swell the polymer shell of the encapsulated powder, thereby P penetrates into the solvent. To test the extraction efficiency of different solvents, three analyses were performed using three solvents with different dielectric constants. The extraction results are summarized in Table 2 below.

[0117] Table 2: Packages with 5% and 20% wall thickness HPLC analysis of P samples

[0118]

[0119] It appears that isopropyl alcohol (IPA) is less capable of extraction than methanol or acetonitrile.These extraction results demonstrate that the interfacial polymerization method used to make the encapsulated powder is capable of successfully encapsulating large amounts of liquid peroxide (up to 93 wt%).

[0120] Example 5: Use PXL50 and packaged P-cured Dow Silastic TM TR-55 Silicon rubber

[0121] Material: P is tert-butyl perbenzoate, an organic peroxide produced by Arkema Co., Ltd. Dow Silastic TM TR-55 silicone rubber is a VMQ type silicone rubber. VMQ is the ASTM designation for peroxide-cured vinyl methyl silicone rubber.

[0122] Unencapsulated powder forms can be prepared from liquid peroxides by adding or absorbing the peroxide onto silica fillers. P XL50 sample:

[0123] 5.00g P (purity 99%) liquid peroxide

[0124] 4.90g Hi-Sil 233 silica from PPG

[0125] 9.90 g of P XL50 (50% purity) free-flowing powdered peroxide

[0126] Use Brabender (CW Brabender) mixer equipped with the Sigma-type blade that does not heat (room temperature mixing), 50g silicone rubber is added to the mixing chamber, mixing speed is 25rpm, then add the solid form of various organic peroxides weighed through Mettler (Mettler) analytical balance. Rubber is mixed for three minutes, taken out from bowl, and mixed for three more minutes. Then, without using any heating, uncured rubber is carefully cold-pressed into sheet material, to about 3 / 16 inch (4.8mm) thick. Then uncured silicone rubber sheet is placed on aluminum foil (not covered) and stored on laboratory table. The sample of this rubber sheet is used for curing research, and is compared with the aging days of uncured rubber sheet on workbench. The loss of solidification corresponds to the loss caused by peroxide because of evaporation.

[0127] The following quantities of rubber and peroxide were weighed to prepare silicone rubber samples containing various peroxides for use in Alpha Technologies Ltd. The test was carried out on a 2000 rheometer.

[0128] Preparation containing unencapsulated PXL50 silicone rubber sample:

[0129] 50.00g Silastic TM TR-55

[0130] 0.2500g P XL50

[0131] Preparation of encapsulated Silicone rubber sample of P (20% wall thickness):

[0132] 50.00g Silastic TM TR-55

[0133] 0.5000g 20% ​​wall thickness (packaging P)

[0134] Preparation of encapsulated Silicone rubber sample with P (5% wall thickness):

[0135] 50.00g Silastic TM TR-55

[0136] 0.5000g 5% wall thickness (package P)

[0137] Over time, 5 g of uncured rubber sheet samples were taken and The test was carried out on a 2000 rheometer. The rubber was placed on two The relative extent of cross-linking was investigated between films (provided by Alpha Technologies Co., Ltd.). The test conditions used in 2000 were: upper and lower die temperatures of 170°C, a frequency of 100 cpm, an applied strain of 1° arc, and a test time of 15 minutes.

[0138] MH = Maximum torque (dN-m)

[0139] ML=Minimum torque (dN-m)

[0140] MH-ML is the delta torque in dN-m and is defined as the relative degree of crosslinking.

[0141] MH-ML (dN-m) is manufactured by Alpha Technology Co., Ltd. The delta torque values ​​obtained by the 2000 Rheometer provide information about the relative degree of crosslinking. The higher the MH-ML delta torque value (dN-m), the higher the relative degree of crosslinking.

[0142] The relative degree of crosslinking (dN-m torque) of uncured rubber sheets stored on a benchtop was studied over time. The degree of crosslinking can be used to determine the percentage change in the degree of cure over time (cure loss). The cure results are reported in Table 3 below.

[0143] Table 3: P XL50 and packaged P-cured Dow Silastic TM TR-55 silicone rubber

[0144]

[0145] In summary, the 5% wall thickness package When peroxide was incorporated into silicone rubber and aged uncovered on a benchtop for 24 days, an unexpectedly excellent relative crosslinking degree of 19.7 dNm (at 170°C) was achieved, representing only a minor change of 3.57% from the 0 (zero) day crosslinking value of 20.43 dNm. There was essentially no loss of crosslinking after aging the rubber compound uncovered on a benchtop for 24 days at room temperature. Thus, this novel peroxide encapsulation method unexpectedly prevents the undesirable evaporation (loss) of peroxide from the silicone elastomer compound over time.

[0146] In comparison, standard unencapsulated The P XL50 peroxide showed a significant loss of 27.8% in cure after 24 days, with the relative degree of crosslinking decreasing from 19.93 dNm to 14.39 dNm.

[0147] Thus, the 5% wall thickness encapsulated peroxide provided an unexpected degree of crosslink retention over time that was superior to the other peroxide samples tested. The 20% wall thickness encapsulated peroxide produced a visually darker cured silicone rubber RPA disk. The cured silicone rubber discs formed by P look similar to those formed using standard unencapsulated The cured product obtained with PXL50 peroxide is similar. The silicone rubber is translucent and unfilled. However, when using mineral-filled or carbon black-filled elastomers, the color caused by using thicker encapsulation is not a problem. When using encapsulated peroxide at 20% wall thickness, the color is not as bad as that of the unencapsulated standard. Compared to PXL50 peroxide, it still surprisingly provided better results.

[0148] Although the embodiments have been described with reference to specific exemplary embodiments and examples, the embodiments disclosed herein are for illustrative purposes only, and various modifications and variations may be made by those skilled in the art without departing from the spirit and scope of the invention as described in the appended claims.

[0149] Prophetic Embodiments

[0150] Prophetic Example 6: Using Unpackaged Standard Liquid P and package 5% wall P's new Solid powder form curing polyester resin

[0151] P is tert-butyl peroxybenzoate, a standard unpackaged liquid organic peroxide produced by Arkema Ltd. Using the teachings of the present invention to package liquid peroxides, and using the following formula to calculate the % wall thickness, in the present invention, the standard liquid P peroxide preparation of new 5% wall thickness package P solid powder sample.

[0152]

[0153] The liquid P (purity 98%) solid powder encapsulation with 5% wall thickness P (purity 25%) is used to cure polyester resin. The amount of the two peroxides added is based on the purity % in the polyester resin to provide an equivalent amount of peroxide. Therefore, in the standard polyester resin, 2phr of liquid Solid encapsulation of P (98% purity) with 7.84phr5% wall P (purity 25%) was used for comparison and then cured at 80°C using the standard composite gel test procedure (ASTM D2471). Table 4 shows the results of the tests with pure and unencapsulated P and solid packaging Peak exotherm time of polyester resin prepared by P. Surprisingly, solid encapsulation P than liquid unencapsulated The P peroxide cured the polyester resin earlier. This demonstrates that the novel polyurea encapsulation not only protects the organic peroxide at standard storage and handling temperatures but also unexpectedly accelerates the cure of the polyester resin at elevated cure temperatures. A shorter time to peak exotherm indicates a faster cure rate.

[0154] Table 4: Encapsulation with new 5% wall P-cured polyester resin with standard liquid Comparison of P-cured polyester resins

[0155]

Claims

1. A packaged liquid organic peroxide particle comprising: a liquid organic peroxide encapsulated by a polyurea shell, wherein the liquid organic peroxide comprises from about 60% to about 95% by weight of the total weight of the encapsulated liquid organic peroxide particles; and optionally a desiccant.

2. The packaged liquid organic peroxide particles of claim 1, wherein the liquid organic peroxide is selected from the group consisting of diacyl peroxides, dialkyl peroxides, peroxyketal peroxides, peroxydicarbonate peroxides, peroxyesters, monoperoxycarbonate peroxides, hydroperoxides, and mixtures thereof.

3. The packaged liquid organic peroxide particles of any one of claim 1 or claim 2, wherein the liquid organic peroxide is selected from the group consisting of tert-butyl peroxybenzoate, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-di(tert-butylperoxy)cyclohexane, O-O-(tert-butyl)O-(2-ethylhexyl)monoperoxycarbonate, and mixtures thereof.

4. The encapsulated liquid organic peroxide particle according to any one of claims 1 to 3, wherein the polyurea shell is polymerized from an amine, an amine mixture or an amine-containing reactant and a liquid organic solution comprising at least one isocyanate; preferably, the at least one isocyanate is selected from the group consisting of aliphatic isocyanates, cyclic isocyanates and / or aromatic isocyanates, and combinations thereof; more preferably, the at least one isocyanate is selected from the group consisting of hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), methylene dicyclohexyl diisocyanate, hydrogenated MDI, and combinations thereof.

5. The packaged liquid organic peroxide particles of claim 4, wherein the amine mixture comprises two or more amines or amine-containing reactants, preferably diethylenetriamine (DETA) and ethylenediamine (EDA), more preferably the molar ratio of DETA to EDA is 10 / 90 to 90 / 10.

6. The packaged liquid organic peroxide particles of claim 4, wherein the at least one isocyanate has a solubility in the liquid organic solution of about 0.08 wt% to 100 wt%, preferably about 20 wt% to 100 wt%, more preferably about 50 wt% to about 100 wt%.

7. The packaged liquid organic peroxide particle of any one of claims 4 to 6, wherein the thickness of the polyurea shell ranges from about 0.1 to 50% based on the amount of amine and isocyanate relative to the total amount of amine, isocyanate and organic liquid peroxide.

8. The packaged liquid organic peroxide particles of any one of claims 1 to 7, wherein the packaged liquid organic peroxide particles have a particle size range of about 1 to 150 μm.

9. The packaged liquid organic peroxide particles of any one of claims 1 to 8, wherein the liquid organic peroxide comprises from about 70 wt% to about 95 wt%, preferably from about 80 wt% to about 95 wt%, more preferably from about 90 wt% to 95 wt%, of the total weight of the packaged liquid organic peroxide particles.

10. The packaged liquid organic peroxide particles according to any one of claims 1 to 9, wherein the packaged liquid organic peroxide particles are solid, preferably powder, and optionally contain one or more of a desiccant, preferably silica, xanthan gum, a biocide and an additive.

11. Encapsulated liquid organic peroxide particles comprising a liquid organic peroxide encapsulated by a polyurea shell, wherein the polyurea shell is formed by polymerization between an aqueous solution of a preformed amine and an organic solution comprising at least one isocyanate.

12. A method for producing encapsulated liquid peroxide particles by polymerization, comprising the steps of: - preparing an organic phase solution comprising at least one isocyanate dispersed in a liquid organic peroxide, - preparing an aqueous phase solution comprising at least one surfactant, - mixing the organic phase solution with the aqueous phase solution to form an emulsion, - adding an aqueous solution comprising at least one amine to the emulsion, - mixing the aqueous solution and the emulsion for a period of time until a solution comprising encapsulated liquid peroxide particles is produced, and - Isolating and optionally drying the encapsulated liquid peroxide particles.

13. The method of claim 12, wherein the at least one surfactant is selected from the group consisting of polyvinyl pyrrolidone, polyvinyl alcohol, and combinations thereof, and the aqueous solution of amines comprises a mixture of at least two different amines.

14. The method of claim 12, wherein the encapsulated liquid peroxide particles are separated from a solution containing the particles by a phase separation process, wherein the phase separation process recovers an organic phase containing the encapsulated liquid peroxide particles.

15. The method of claim 12, wherein the liquid organic peroxide is one or more liquid organic peroxides selected from the group consisting of diacyl peroxides, dialkyl peroxides, peroxyketal peroxides, peroxydicarbonate peroxides, monoperoxycarbonate peroxides, peroxyesters, hydroperoxides, tert-butyl peroxybenzoate, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-di(tert-butylperoxy)cyclohexane, OO-(tert-butyl)O-(2-ethylhexyl)monoperoxycarbonate, and combinations thereof.

16. The method of claim 12, wherein the amine is diethylenetriamine (DETA), ethylenediamine (EDA), or a combination thereof, wherein Preferably the molar ratio of DETA to EDA in the mixture of amines is from 10 / 90 to 90 / 10.

17. The method of claim 12, wherein the at least one isocyanate is selected from the group consisting of aliphatic isocyanates, cyclic isocyanates, aromatic isocyanates, methylene diphenyl diisocyanate (MDI), poly(hexamethylene diisocyanate) (HMDI), and combinations thereof.

18. The packaged liquid organic peroxide particles according to any one of claims 1 to 11, wherein the packaged liquid organic peroxide particles are solid, the solid containing less than 10% water and / or organic solvent, preferably less than 5% water and / or organic solvent, and more preferably less than 2% water and / or organic solvent, based on the total weight of the packaged organic peroxide particles.

19. An emulsion comprising the encapsulated liquid organic peroxide particles of any one of claims 1 to 11.

20. A masterbatch or ready-to-cure composition comprising at least one encapsulated organic peroxide particle according to any one of claims 1 to 11 and at least one elastomer.

21. The masterbatch or ready-to-cure composition of claim 20, wherein the at least one elastomer is at least one of silicone, EPDM, polyethylene, chlorinated polyethylene, and a fluoroelastomer.

22. A composition comprising at least one encapsulated organic peroxide according to any one of claims 1 to 11, at least one liquid polyester resin and optionally fillers and / or fiber reinforcements.

23. The composition of claim 22, which is cured using pultrusion, compression molding, mass molding and / or potting to form a cross-linked composite.

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