Continuous production of aqueous emulsions of organic peroxides

Abstract

The present disclosure relates to a continuous process for producing aqueous emulsions of organic peroxides comprising organic peroxides having a low self-accelerated decomposition temperature, and a system for performing the continuous process.

Description

Technical Field

[0001] The present disclosure relates to a continuous process for producing an aqueous organic peroxide emulsion comprising an organic peroxide having a low self-accelerating decomposition temperature, and a system for performing the continuous process. Background Art

[0002] There are many conventional methods for producing aqueous organic peroxide emulsions in the art. For example, WO 99 / 31194 explains that the emulsification step can be carried out by using any conventional dispersing equipment, for example by means of a paddle, propeller or turbine mechanical rotating agitator, a colloid mill, a homogenizer (such as an ultrasonic homogenizer), a high-speed shearing device and an inline mixer.

[0003] While these conventional options can be used to prepare aqueous emulsions of various temperature-stable organic peroxides, the methods currently available for organic peroxides with poor thermal stability are very limited. In this regard, for organic peroxides with low self-accelerating decomposition temperatures ("SADT"; e.g., about 25°C or less), the emulsification processes used to date have been batch processes. This is because the organic peroxide mixture must be maintained at a low temperature (usually around or below 0°C) to prevent the organic peroxide from rapidly decomposing during the emulsification process, which can be extremely dangerous (e.g., can result in an explosion). Therefore, it is considered too dangerous to attempt to produce aqueous emulsions of these peroxides in a continuous manner on an industrial scale.

[0004] US 6350835 discloses an aqueous peroxyester emulsion that is liquid at -20° C. US 6350835 explains that the emulsification process is preferably carried out at a temperature below the SADT of the peroxyester, but fails to explain how the emulsification process is carried out in a safe and continuous manner; the working examples of US 6350835 only provide a conventional batch method for producing such an aqueous peroxyester emulsion.

[0005] US 4734135 discloses an aqueous emulsion of peroxydicarbonate and diacyl peroxide. Like US 6350835, the working example of US 4734135 only provides a conventional batch method for producing an aqueous emulsion of this type of peroxide. Although US4734135 infers that the emulsifying step "can be carried out continuously by an emulsifying device (such as an in-line mixer) with a cooling device" (i.e. an in-line mixer with a jacket (cooling jacket)), this is neither illustrated in US 4734135, nor described to enable those skilled in the art to simplify it in a straightforward manner to be applied to any further technical details of any peroxide (certainly not those peroxides with low SADT).

[0006] It is well known that continuous processes have many advantages over batch processes. For example, continuous processes have increased productivity and generally require a smaller equipment footprint. However, to the best of the inventors' knowledge, a successful, commercial-scale continuous process for producing aqueous emulsions of organic peroxides having low SADT has not yet been developed. Summary of the invention

[0007] Therefore, one object of the present disclosure is to develop a continuous process for producing aqueous emulsions of organic peroxides with low SADT. Another object is to achieve this goal without developing new dedicated equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a schematic diagram of a system according to the present invention. DETAILED DESCRIPTION

[0009] The present inventors have discovered that these objectives can be achieved using readily available equipment. In this regard, by cooling a pre-emulsified mixture containing an organic peroxide prior to feeding it to an in-line emulsifier, followed by cooling the organic peroxide emulsion using a downstream heat exchanger, the present inventors have developed a significantly simpler yet highly effective process and apparatus arrangement that addresses a long felt need for a continuous process for producing an aqueous emulsion of an organic peroxide having a low SADT.

[0010] Therefore, in a first aspect, the present invention relates to a continuous process for producing an organic peroxide emulsion, the process comprising:

[0011] a) feeding a pre-emulsified mixture to an inlet of an in-line emulsifier, wherein the pre-emulsified mixture comprises at least one organic peroxide having a self-accelerating decomposition temperature (SADT) of 25°C or less, at least one protective colloid, at least one antifreeze agent, water and optionally at least one emulsifier, and wherein the pre-emulsified mixture is fed to the inlet at a temperature of at least 12°C below the SADT of the organic peroxide, preferably at least 14°C below the SADT of the organic peroxide, more preferably about 15°C to about 35°C below the SADT of the organic peroxide, and most preferably about 15°C to about 25°C below the SADT of the organic peroxide, such as about 15°C to about 20°C below the SADT of the organic peroxide; and

[0012] b) transferring the aqueous organic peroxide emulsion from the outlet of the in-line emulsifier to a heat exchanger located downstream of the outlet of the in-line emulsifier, wherein the heat exchanger reduces the temperature of the aqueous organic peroxide emulsion to a temperature that is at least 12°C lower than the SADT of the organic peroxide, preferably at least 14°C lower than the SADT of the organic peroxide, more preferably about 15°C to about 35°C lower than the SADT of the organic peroxide, and most preferably about 15°C to about 25°C lower than the SADT of the organic peroxide, such as about 15°C to about 20°C lower than the SADT of the organic peroxide.

[0013] In a second aspect, the present invention relates to a system for continuously producing an organic peroxide emulsion, the system comprising:

[0014] at least one container for preparing and / or receiving a pre-emulsified mixture comprising at least one organic peroxide having a self-accelerating decomposition temperature (SADT) of 25°C or less, at least one protective colloid, at least one antifreeze agent, water and optionally at least one emulsifier, wherein the at least one container comprises means for cooling the pre-emulsified mixture and / or maintaining the pre-emulsified mixture at a temperature of at least 12°C below the SADT of the organic peroxide, preferably at least 14°C below the SADT of the organic peroxide, more preferably about 15°C to about 35°C below the SADT of the organic peroxide and most preferably about 15°C to about 25°C below the SADT of the organic peroxide, such as about 15°C to about 20°C below the SADT of the organic peroxide;

[0015] an in-line emulsifier comprising at least one inlet and at least one outlet, wherein the in-line emulsifier is in fluid communication with the at least one vessel and is located downstream of the at least one vessel and is configured to receive the pre-emulsified mixture at the at least one inlet at a temperature of at least 12°C below the SADT of the organic peroxide, preferably at least 14°C below the SADT of the organic peroxide, more preferably about 15°C to about 35°C below the SADT of the organic peroxide, and most preferably about 15°C to about 25°C below the SADT of the organic peroxide, such as about 15°C to about 20°C below the SADT of the organic peroxide;

[0016] a heat exchanger in fluid communication with the in-line emulsifier and located downstream of the in-line emulsifier, wherein the heat exchanger is configured to reduce the temperature of the aqueous organic peroxide emulsion obtained from the at least one outlet of the in-line emulsifier to a temperature that is at least 12°C lower than the SADT of the organic peroxide, preferably at least 14°C lower than the SADT of the organic peroxide, more preferably about 15°C to about 35°C lower than the SADT of the organic peroxide, and most preferably about 15°C to about 25°C lower than the SADT of the organic peroxide, such as, for example, about 15°C to about 20°C lower than the SADT of the organic peroxide; and

[0017] - An optional pack-out unit in fluid communication with and downstream of the heat exchanger.

[0018] By using a specific feed temperature combined with the introduction of a heat exchanger downstream of the in-line emulsifier outlet, the safety of the emulsification process has been greatly improved to the point where it can now be safely performed in a continuous and highly scalable manner (ie continuously on an industrial scale).

[0019] For the avoidance of any doubt, a "pre-emulsified mixture" is a mixture of components that has not yet been subjected to emulsification conditions (and therefore is not yet in the form of a stable emulsion).

[0020] The cooled organic peroxide aqueous emulsion obtained in step b) can be used directly (i.e., produced and used on site), or can be transferred to a packaging discharging unit (to be packaged and transported) located downstream of the heat exchanger. In this regard, the invention provides a system for continuous on-site production of organic peroxide aqueous emulsions, with a small footprint and easy installation, wherein the organic peroxide has a low SADT. This is significantly improved in terms of ease of production, cost, safety and environmental impact (less raw material quantity to be transported).

[0021] SADT is the lowest ambient temperature at which self-accelerating decomposition of a product occurs in a package intended for transport. The method for determining the SADT of an organic peroxide is described in detail in the United Nations Manual of Tests and Criteria, Seventh Revised Edition (2019), Test Series H.4: Heat accumulation storage test, which is incorporated herein by reference. The method determines the lowest constant ambient air temperature at which an exothermic decomposition of a thermally unstable substance occurs under conditions representative of the substance when packaged. The method is based on the Semenov theory of thermal explosion, i.e., the assumption that the main resistance to heat flow is at the container wall. The method can be used to determine the SADT of a substance in its packaging (including IBCs (Intermediate Bulk Containers) and small tanks (up to 2 m 3 For the avoidance of doubt, the SADT values ​​referred to herein are determined according to the method specified in the above-mentioned United Nations Manual (Test Series H.4: Heat Accumulation Storage Test) for organic peroxides in high density polyethylene (HDPE) packaging with a volume of 20 to 30 liters.

[0022] The emulsion contains at least one organic peroxide having a self-accelerating decomposition temperature (SADT) of 25°C or less, preferably 20°C or less, preferably 15°C or less, preferably 10°C or less, preferably 5°C or less, and the SADT may be about 0°C or less. Preferred organic peroxides include peroxyesters, peroxydicarbonates and diacyl peroxides. Peroxyesters and diacyl peroxides are preferred. Examples of preferred organic peroxides for use according to the invention are diisobutyryl peroxide (SADT 0°C), di-n-propyl peroxydicarbonate (SADT 0°C), diisopropyl peroxydicarbonate (SADT 5°C), di-n-butyl peroxydicarbonate (SADT 0°C), di-sec-butyl peroxydicarbonate (SADT 0°C), di(2-ethoxyethyl) peroxydicarbonate (SADT 10°C), di(2-ethylhexyl) peroxydicarbonate (SADT 5°C), 1,3-di(propane-2,2-diyl)benzenebis(neodecanoyl)peroxide (SADT 10°C), 1,1,3,3-tetramethylbutyl peroxyneodecanoate (SADT 15°C), 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate (SADT 10°C); tert-amyl peroxyneodecanoate (SADT 20°C); isopropyl peroxyneodecanoate (SADT 5°C). 10℃); di-n-butyryl peroxide (SADT 25℃); tert-butyl peroxyneodecanoate (SADT 20℃); 1,1,3,3-tetramethylbutyl peroxypivalate (SADT 20℃); tert-amyl peroxypivalate (SADT 25℃); tert-butyl peroxypivalate (SADT 25℃); di(3,5,5-trimethylhexanoyl) peroxide (SADT 25℃) or a mixture thereof.

[0023] The organic peroxide emulsion typically contains 25-70 wt % of the organic peroxide, based on the total weight of the emulsion. Preferably, the amount of organic peroxide in the emulsion is 30-65 wt %, more preferably 35-60 wt %, and most preferably 40-60 wt %. The organic peroxide can be introduced into the emulsification method disclosed herein in the form of a sensitized organic peroxide. In this regard, any suitable sensitizer can be used to dilute and / or dissolve the peroxide, such as an inert sensitizing solvent. Such inert sensitizing solvents are well known in the art and include, for example, isododecane and mineral oil. For example, 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate (SADT 10°C) is prepared as a 75% solution in odorless mineral spirits (" 193-CH75") in desensitized form from Commercially available.

[0024] The amount of water in the emulsion is generally 20-70 wt%, more preferably 25-50 wt% and most preferably 25-40 wt%, based on the total weight of the emulsion.

[0025] The emulsion contains at least one antifreeze agent and can comprise the combination of two or more antifreeze agents. Any conventional antifreeze agent can be used. Preferably, methanol, ethanol, isopropanol, (second) glycol, propylene glycol, glycerine and mixtures thereof are used, more preferably, methanol, ethanol, propylene glycol and mixtures thereof are used. Known antifreeze agents have almost no effect on the polymerization process. The technician has no difficulty in balancing the ratio of water and antifreeze agent. Usually, the amount of the antifreeze agent used in the emulsion according to the present invention will be lower than the amount of water.

[0026] The emulsion also contains at least one protective colloid. Any conventional protective colloid can be used. Suitable protective colloids include partially hydrolyzed (or saponified) polyvinyl acetate, polyvinyl pyrrolidone, polyacrylate, cellulose, cellulose derivatives, starch and starch derivatives. Particularly useful are partially hydrolyzed / saponified polyvinyl acetate, cellulose, cellulose derivatives, starch and starch derivatives. Typically, polyvinyl acetate (PVA) is used, preferably a PVA with a degree of hydrolysis of 50-90 mol %, more preferably 55-80 mol %, more preferably 60-70 mol %. The amount of the protective colloid used in the emulsion according to the present invention will depend on the type and amount of the organic peroxide and the desired viscosity of the final emulsion, but is typically used in an amount of about 0.1 to about 5 wt % based on the total weight of the emulsion.

[0027] Emulsions according to the present invention may contain at least one conventional emulsifier. Suitable emulsifiers are known to those skilled in the art, and they include nonionic, anionic, cationic and amphoteric surfactants and mixtures thereof. These emulsifiers can be added in their usual amount, such as about 0.05 to about 4 weight percent based on the total weight of the emulsion. Preferably, nonionic surfactants are used, more preferably HLB (hydrophile-lipophile balance) values ​​are 7 or higher, even more preferably 16 or higher. Alternatively, emulsions according to the present invention may contain a very small amount of emulsifier, or may not contain an emulsifier at all. It has been found that substantially or completely removing emulsifiers (most notably emulsifiers in the form of nonionic, anionic, cationic and amphoteric surfactants) from peroxide emulsions is very beneficial to the production of polyvinyl chloride (PVC). In this regard, it has been found that such "emulsifier-free" emulsions of peroxides with low SADT (particularly diisobutyryl peroxide, SADT 0°C) produce high-quality PVC from vinyl chloride monomer (VCM) and unexpectedly improve the drying properties of the polymer (the drying rate of the resulting PVC polymer is significantly increased, thereby shortening the drying time of the polymer, which is very important for industrial-scale PVC production). Therefore, in a preferred embodiment, the emulsion according to the present invention may contain a total amount of 0% to 0.17% by weight of emulsifiers, based on the total weight of the emulsion. Also preferably, the emulsion according to the present invention may contain 0% to 0.17% by weight, more preferably 0% by weight, of (non-ionic) surfactants having an HLB (hydrophile-lipophile balance) value of 7 or more (weight % based on the total weight of the emulsion). Therefore, the emulsion according to the present invention may contain a total amount of 0% to about 4% by weight of emulsifiers, based on the total weight of the emulsion.

[0028] The organic peroxide aqueous emulsion of the present invention may also optionally contain other additives, including pH regulators (such as phosphate and citrate buffers), chelating agents, biocides (e.g., fungicides), antiozonants, antioxidants, antidegradants, ultraviolet stabilizers, coagents, comonomers, antistatic agents, foaming agents, release agents, and processing oils. These additives may be added in their usual amounts.

[0029] The methods and systems of the present disclosure require an online emulsifier. Online emulsifiers suitable for use in the present method are well known in the art, such as (but not limited to) those discussed in WO 99 / 31194 and described in US 2004 / 223407, and suitable online emulsifiers are widely available, such as (but not limited to) Process Pilot 2000, DRS2000 and available from GmbH & Co. KG. and their scaled-up equivalents. These well-known in-line emulsifiers are not typically used at low operating temperatures (e.g., below zero degrees), but it is straightforward to make routine modifications to these emulsifiers to accommodate low temperatures (e.g., by changing the material of replaceable components (such as O-rings) to materials known to be mechanically stable at very low temperatures). Such routine modifications are well within the routine capabilities of those skilled in the art.

[0030] Preferably, the residence time of the organic peroxide mixture in the in-line emulsifier is between about 1 and about 10 seconds, preferably between about 2 and about 8 seconds and more preferably between about 3 and about 6 seconds, such as about 3.8 to about 5.5 seconds.

[0031] The online emulsifier preferably includes at least one grinding head, preferably at least two grinding heads, and may include at least three grinding heads. The online emulsifier may include grinding heads in a rotor-stator arrangement, and may be configured as a single-stage rotor-stator system, or may be configured as a multi-stage (e.g., two-stage or three-stage) rotor-stator system. The grinding head may be coarse, medium, fine, or a combination thereof. In a preferred embodiment, the tip speed of the grinding head or each grinding head is from about 15 meters per second (m / s) to about 50 m / s, preferably from about 20 m / s to about 45 m / s, and more preferably from about 25 m / s to about 40 m / s.

[0032] It is well within the routine capabilities of those skilled in the art to configure in-line emulsifiers known in the art to operate within these operating parameters.

[0033] Therefore, in a preferred embodiment, the continuous process for producing an organic peroxide emulsion comprises:

[0034] a) feeding a pre-emulsified mixture to an inlet of an in-line emulsifier, wherein the in-line emulsifier comprises at least one milling head, preferably at least two milling heads, wherein the or each milling head has a tip speed of from 15 m / s to 50 m / s, preferably from about 20 m / s to about 45 m / s and more preferably from about 25 m / s to about 40 m / s, wherein the pre-emulsified mixture comprises at least one organic peroxide having a self-accelerating decomposition temperature (SADT) of 25°C or less, at least one protective colloid, at least one antifreeze agent, water and optionally at least one emulsifier, and wherein the pre-emulsified mixture is fed to the inlet at a temperature of at least 12°C below the SADT of the organic peroxide, preferably at least 14°C below the SADT of the organic peroxide, more preferably from about 15°C to about 35°C below the SADT of the organic peroxide and most preferably from about 15°C to about 25°C below the SADT of the organic peroxide, such as from about 15°C to about 20°C below the SADT of the organic peroxide;

[0035] b) transferring the aqueous organic peroxide emulsion from the outlet of the in-line emulsifier to a heat exchanger located downstream of the outlet of the in-line emulsifier, wherein the heat exchanger reduces the temperature of the aqueous organic peroxide emulsion to a temperature at least 12°C below the SADT of the organic peroxide, preferably at least 14°C below the SADT of the organic peroxide, more preferably about 15°C to about 35°C below the SADT of the organic peroxide, and most preferably about 15°C to about 25°C below the SADT of the organic peroxide, such as about 15°C to about 20°C below the SADT of the organic peroxide,

[0036] The residence time of the pre-emulsified mixture in the in-line emulsifier is between about 1 and about 10 seconds, preferably between about 2 and about 8 seconds, and more preferably between about 3 and about 6 seconds, such as about 3.8 to about 5.5 seconds.

[0037] In a preferred embodiment, the system for continuously producing an organic peroxide emulsion comprises:

[0038] at least one vessel (e.g. at least one (continuous) stirred tank reactor) for preparing and / or receiving a pre-emulsified mixture comprising at least one organic peroxide having a self-accelerating decomposition temperature (SADT) of 25°C or less, at least one protective colloid, at least one antifreeze agent, water and optionally at least one emulsifier, wherein the at least one vessel comprises means (e.g. internal and / or external cooling coils, external cooling jacket, etc.) for cooling the pre-emulsified mixture and / or maintaining the pre-emulsified mixture at a temperature of at least 12°C below the SADT of the organic peroxide, preferably at least 14°C below the SADT of the organic peroxide, more preferably about 15°C to about 35°C below the SADT of the organic peroxide and most preferably about 15°C to about 25°C below the SADT of the organic peroxide, such as about 15°C to about 20°C below the SADT of the organic peroxide;

[0039] an in-line emulsifier comprising at least one inlet and at least one outlet, wherein the in-line emulsifier comprises at least one milling head, preferably at least two milling heads, wherein the milling head or each milling head is configured to have a tip speed of 15 to 50 m / s, preferably about 20 to about 45 m / s and more preferably about 25 to about 40 m / s, wherein the in-line emulsifier is in fluid communication with the at least one vessel and is located downstream of the at least one vessel and is configured to receive the pre-emulsified mixture at the at least one inlet at a temperature of at least 12°C below the SADT of the organic peroxide, preferably at least 14°C below the SADT of the organic peroxide, more preferably about 15 to about 35°C below the SADT of the organic peroxide and most preferably about 15 to about 25°C below the SADT of the organic peroxide, such as about 15 to about 20°C below the SADT of the organic peroxide;

[0040] a heat exchanger in fluid communication with the in-line emulsifier and located downstream of the in-line emulsifier, wherein the heat exchanger is configured to reduce the temperature of the aqueous organic peroxide emulsion obtained from the at least one outlet of the in-line emulsifier to a temperature that is at least 12°C lower than the SADT of the organic peroxide, preferably at least 14°C lower than the SADT of the organic peroxide, more preferably about 15°C to about 35°C lower than the SADT of the organic peroxide, and most preferably about 15°C to about 25°C lower than the SADT of the organic peroxide, such as, for example, about 15°C to about 20°C lower than the SADT of the organic peroxide; and

[0041] An optional package discharge unit located downstream of the heat exchanger;

[0042] The system is configured such that the residence time of the pre-emulsified mixture in the in-line emulsifier is between about 1 and about 10 seconds, preferably between about 2 and about 8 seconds, and more preferably between about 3 and about 6 seconds, such as about 3.8 to about 5.5 seconds.

[0043] In a preferred embodiment, the system further comprises at least one mixing device that is fluidly connected to and upstream of at least one container for preparing and / or receiving the pre-emulsified mixture. In the embodiment, the at least one mixing device prepares a mixture comprising a protective colloid, an antifreeze agent, water, and an optional emulsifier. The mixture is then transferred to the at least one container, where it is mixed with the at least one organic peroxide having a SADT of 25° C. or less to form a pre-emulsified mixture. In one embodiment, the mixing device can be a continuously stirred tank reactor (CSTR). In another embodiment, the mixing device can be an in-line static mixer comprising one or more static mixer elements. Such mixers are well known to those skilled in the art.

[0044] Therefore, in a preferred embodiment, the present invention relates to a system for continuously producing an organic peroxide emulsion, the system comprising:

[0045] at least one mixing device for preparing a mixture comprising at least one protective colloid, at least one antifreeze agent, water and optionally at least one emulsifier;

[0046] at least one container in fluid communication with the at least one mixing device and located downstream of the at least one mixing device and configured to receive the mixture comprising at least one protective colloid, at least one antifreeze agent, water and optionally at least one emulsifier, the at least one container being further configured to separately receive at least one organic peroxide having a self-accelerating decomposition temperature (SADT) of 25°C or less and prepare a pre-emulsified mixture comprising the at least one organic peroxide having a self-accelerating decomposition temperature (SADT) of 25°C or less, at least one protective colloid, at least one antifreeze agent, water and optionally at least one emulsifier, wherein the at least one container comprises means for cooling the pre-emulsified mixture and / or maintaining the pre-emulsified mixture at a temperature of at least 12°C below the SADT of the organic peroxide, preferably at least 14°C below the SADT of the organic peroxide, more preferably about 15°C to about 35°C below the SADT of the organic peroxide, and most preferably about 15°C to about 25°C below the SADT of the organic peroxide, such as about 15°C to about 20°C below the SADT of the organic peroxide;

[0047] an in-line emulsifier comprising at least one inlet and at least one outlet, wherein the in-line emulsifier is in fluid communication with the at least one vessel and is located downstream of the at least one vessel and is configured to receive the pre-emulsified mixture at the at least one inlet at a temperature of at least 12°C below the SADT of the organic peroxide, preferably at least 14°C below the SADT of the organic peroxide, more preferably about 15°C to about 35°C below the SADT of the organic peroxide, and most preferably about 15°C to about 25°C below the SADT of the organic peroxide, such as about 15°C to about 20°C below the SADT of the organic peroxide;

[0048] a heat exchanger in fluid communication with the in-line emulsifier and located downstream of the in-line emulsifier, wherein the heat exchanger is configured to reduce the temperature of the aqueous organic peroxide emulsion obtained from the at least one outlet of the in-line emulsifier to a temperature that is at least 12°C lower than the SADT of the organic peroxide, preferably at least 14°C lower than the SADT of the organic peroxide, more preferably about 15°C to about 35°C lower than the SADT of the organic peroxide, and most preferably about 15°C to about 25°C lower than the SADT of the organic peroxide, such as about 15°C to about 20°C lower than the SADT of the organic peroxide; and

[0049] - An optional package outfeed unit in fluid communication with and downstream of the heat exchanger.

[0050] It is noted that the various elements of the present invention (including but not limited to the preferred ranges of various parameters) can be combined unless the elements are mutually exclusive.

[0051] The present invention will be described by the following embodiments in conjunction with the accompanying drawings, but the present invention is not limited thereto.

[0052] Working Example

[0053] refer to Figure 1 , developed a continuous process for the production of aqueous emulsions of diisobutyryl peroxide (SADT 0°C).

[0054] In container 1 A pre-emulsified mixture comprising methanol (15 wt%), polyvinyl acetate having a degree of hydrolysis of 50-75 mol % (1.5 wt%), a nonionic surfactant (1 wt%), diisobutyryl peroxide (40 wt%) and water was cooled to -15°C under stirring.

[0055] The cooled pre-emulsified mixture was taken out of the container at -15°C. 1 Continuous feed to inline emulsifier 2 The inline emulsifier delivers shear force to the pre-emulsified mixture to form a stable diisobutyryl peroxide emulsion. The emulsified product is discharged from the outlet of the inline emulsifier and transferred to the heat exchanger. 3 , where the emulsified product is cooled to -15°C. Subsequently, the product is fed to the packaging buffer tank 4 And the material is packaged and discharged from the downstream packaging line.

[0056] No safety issues were found at any point during the continuous emulsification process.

[0057] Instrument characteristics description:

[0058] 1. A vessel equipped with an agitator and an external cooling coil configured to cool the pre-emulsified mixture contained therein to -15°C

[0059] 2. DRS 2000 / 10 equipment equipped with at least 2 grinding heads, each with a tip speed of about 40 m / s and a peroxide residence time of 3.8 to 5.5 seconds.

[0060] 3. A heat exchanger configured to reduce the temperature of the organic peroxide emulsion to -15°C

[0061] 4. Packaging outfeed unit (buffer tank and downstream packaging container)

[0062] In this specification, unless expressly stated otherwise, the word "or" is used to refer to an operator that returns a true value when one or both of the stated conditions are met, which is different from "exclusive or", which requires that only one condition is met. The word "comprises" is used to mean "comprising" rather than "consisting of". All prior teachings acknowledged above are incorporated herein by reference. The acknowledgement of any previously published document herein is not to be taken as an acknowledgment or representation that its teachings were common general knowledge in Europe or elsewhere at the date of publication of this document.

Claims

1. A continuous method for producing an organic peroxide emulsion, the method comprising: a) feeding a pre-emulsified mixture to an inlet of an in-line emulsifier, wherein the pre-emulsified mixture comprises at least one organic peroxide having a self-accelerating decomposition temperature (SADT) of 25° C. or less, at least one protective colloid, at least one antifreeze agent, water and optionally at least one emulsifier, and wherein the pre-emulsified mixture is fed to the inlet at a temperature at least 12° C. lower than the SADT of the organic peroxide; b) transferring the aqueous organic peroxide emulsion from the outlet of the in-line emulsifier to a heat exchanger located downstream of the outlet of the in-line emulsifier, wherein the heat exchanger reduces the temperature of the aqueous organic peroxide emulsion to a temperature at least 12° C. lower than the SADT of the organic peroxide.

2. The process according to claim 1, wherein the pre-emulsified mixture of step a) is fed to the inlet at a temperature of at least 14°C below the SADT of the organic peroxide, preferably about 15°C to about 35°C below the SADT of the organic peroxide, and most preferably about 15°C to about 25°C below the SADT of the organic peroxide, such as about 15°C to about 20°C below the SADT of the organic peroxide.

3. The process according to any one of the preceding claims, wherein in step b) the heat exchanger reduces the temperature of the organic peroxide emulsion to a temperature at least 14°C below the SADT of the organic peroxide, preferably about 15°C to about 35°C below the SADT of the organic peroxide and most preferably about 15°C to about 25°C below the SADT of the organic peroxide, such as about 15°C to about 20°C below the SADT of the organic peroxide.

4. The method according to any one of the preceding claims, further comprising c) transferring the cooled aqueous organic peroxide emulsion of step b) to a packaging discharge unit located downstream of the heat exchanger.

5. The method according to any one of the preceding claims, wherein the organic peroxide has a self-accelerating decomposition temperature (SADT) of 20°C or less, preferably 15°C or less, preferably 10°C or less, preferably 5°C or less.

6. The method according to any one of the preceding claims, wherein the organic peroxide is selected from peroxyesters, peroxydicarbonates, diacyl peroxides or mixtures thereof.

7. The method according to any one of the preceding claims, wherein the organic peroxide is selected from diisobutyryl peroxide (SADT 0°C), di-n-propyl peroxydicarbonate (SADT 0°C), diisopropyl peroxydicarbonate (SADT 5°C), di-n-butyl peroxydicarbonate (SADT 0°C), di-sec-butyl peroxydicarbonate (SADT 0°C), di(2-ethoxyethyl) peroxydicarbonate (SADT 10°C), di(2-ethylhexyl) peroxydicarbonate (SADT 5°C), 1,3-di(propane-2,2-diyl)benzenebis(neodecanoyl) peroxide (SADT 10°C), 1,1,3,3-tetramethylbutyl peroxyneodecanoate (SADT 15°C), 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate (SADT 10°C); tert-amyl peroxyneodecanoate (SADT 20°C); isophenylpropyl peroxyneodecanoate (SADT 10°C); di-n-butyryl peroxide (SADT 25°C); tert-butyl peroxyneodecanoate (SADT 20°C); 1,1,3,3-tetramethylbutyl peroxypivalate (SADT 20°C); tert-amyl peroxypivalate (SADT25°C); tert-butyl peroxypivalate (SADT 25°C); di(3,5,5-trimethylhexanoyl) peroxide (SADT 25°C), or a mixture thereof.

8. The method according to any one of the preceding claims, wherein the pre-emulsified mixture comprises 25-70 wt% of the organic peroxide, based on the total weight of the pre-emulsified mixture.

9. The method according to any one of the preceding claims, wherein the at least one protective colloid is selected from partially hydrolyzed (or saponified) polyvinyl acetate, polyvinyl pyrrolidone, polyacrylates, cellulose, cellulose derivatives, starch and starch derivatives, preferably partially hydrolyzed (or saponified) polyvinyl acetate.

10. The method according to any one of the preceding claims, wherein the at least one emulsifier is omitted from the pre-emulsified mixture or is selected from nonionic, anionic, cationic and amphoteric surfactants and mixtures thereof, preferably nonionic surfactants.

11. The method according to any one of the preceding claims, wherein the at least one antifreeze agent is selected from methanol, ethanol, isopropanol, (ethylene) glycol, propylene glycol, glycerol and mixtures thereof.

12. A method according to any one of the preceding claims, wherein the in-line emulsifier comprises at least one grinding head, preferably at least two grinding heads, and wherein the tip speed of the or each grinding head is from about 15 meters / second (m / s) to about 50 m / s, preferably from about 20 m / s to about 45 m / s and more preferably from about 25 m / s to about 40 m / s.

13. The method according to any one of the preceding claims, wherein the residence time of the pre-emulsified mixture in the in-line emulsifier is from about 1 to about 10 seconds, preferably from about 2 to about 8 seconds and more preferably from about 3 to about 6 seconds, for example from about 3.8 to about 5.5 seconds.

14. A system for continuously producing an organic peroxide emulsion, the system comprising: at least one container for preparing and / or receiving a pre-emulsified mixture comprising at least one organic peroxide having a self-accelerating decomposition temperature (SADT) of 25°C or less, at least one protective colloid, at least one antifreeze agent, water and optionally at least one emulsifier, wherein the at least one container comprises means for cooling the pre-emulsified mixture and / or maintaining the pre-emulsified mixture at a temperature at least 12°C below the SADT of the organic peroxide; an in-line emulsifier comprising at least one inlet and at least one outlet, wherein the in-line emulsifier is in fluid communication with the at least one vessel and is located downstream of the at least one vessel and is configured to receive the pre-emulsified mixture at the at least one inlet at a temperature at least 12°C lower than the SADT of the organic peroxide; and a heat exchanger in fluid communication with the in-line emulsifier and located downstream of the in-line emulsifier, wherein the heat exchanger is configured to reduce the temperature of the aqueous organic peroxide emulsion obtained from the at least one outlet of the in-line emulsifier to a temperature at least 12° C. lower than the SADT of the organic peroxide.

15. The system of claim 14, further comprising a package outfeed unit located downstream of the heat exchanger.

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