WO2014164619A1

WO2014164619A1 - Method of making a metallosiloxane, borosiloxane, or borometalosiloxane resin and use thereof

Info

Publication number: WO2014164619A1
Application number: PCT/US2014/023020
Authority: WO
Inventors: Leon Cook; Michael DEPIERRO; Jake GILLILAN
Original assignee: Dow Corning Corporation
Priority date: 2013-03-13
Filing date: 2014-03-11
Publication date: 2014-10-09

Abstract

A method of making a metallosiloxane, borosiloxane, or borometalosiloxane resin, optionally phosphorylated and formed into a powder or flakes is described along with a use thereof as a halogen-free, flame retardant for a plastic or polymer composite. This method comprises the steps of: providing a first mixture comprising an alkoxysilane intermediate, optionally a solvent, and optionally a metal-containing material, wherein the alkoxysilane intermediate is capable of forming at least one Si-O-Metal or Si-O-B bond. Adding an alkyl- or aryl-alkoxysilane, and optionally a boron-containing material, and optionally a catalyst, to the first mixture to form a second mixture; allowing the second mixture to react under agitation at a predetermined temperature to form a third mixture comprised of a metallosiloxane, borosiloxane, or borometalosiloxane resin, an alkyl alcohol, and optionally the aromatic solvent; and removing the alkyl alcohol from the third mixture as it is formed during the reaction of the second mixture. At least one of the first and second mixtures includes a metal-containing material or a boron-containing material. Optionally, the aromatic solvent is stripped away from the resin; and optionally a powder or flakes is formed out of the resin.

Description

METHOD OF MAKING A METALLOSILOXANE, BOROSILOXANE, OR

BOROMETALOSILOXANE RESIN AND USE THEREOF

[0001] This disclosure relates generally to a method of making a metallosiloxane, borosiloxane, or borometalosiloxane resin and use thereof. More specifically, this disclosure relates to the preparation of a metallosiloxane, borosiloxane, or borometalosiloxane resin for use as a halogen-free, flame retardant additive in a plastic or polymer composite. The resin being optionally phosphorylated and formed into flakes or powder.

[0002] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0003] Conventional flame retardants that are used in plastic materials, such as polycarbonate, typically contain either bromine or chlorine moieties. However, for plastic materials used in public transportation applications, recently enacted regulations, such as the European Fire and Fumes Standard (EN45545), require the incorporation of halogen free flame retardants. Unfortunately, conventional halogen free additives do not impart all of the flame retardant properties that are expected for plastic materials when they are exposed to flames. These expected flame retardant properties include not only flame inhibition, but also anti-dripping, low smoke generation, low toxicity, and low corrosiveness.

[0004] Silicon-containing materials are considered environmentally friendly and, along with phosphorylated compounds, can exhibit beneficial flame retardant properties. In fact, metallosiloxane, borosiloxane, or borometalosiloxane resins have been synthesized in small quantities that exhibit many of the necessary characteristics of a halogen free flame retardant additive that, either on their own or in conjunction with other additives, can impart the expected flame retardant properties to plastic materials. Although these resins have been synthesized in small quantities, the preparation of large scale production volumes of these resins pose multiple processing challenges.

BRIEF SUMMARY OF THE INVENTION

[0005] This invention generally provides a method of making a metallosiloxane, borosiloxane, or borometalosiloxane resin. This method comprises the steps of: providing a first mixture comprising an alkoxysilane intermediate, optionally, a solvent, and optionally a metal-containing compound; wherein the alkoxysilane intermediate is capable of forming at least one Si-O-Metal or Si-O-B bond; combining an alkyl- or aryl- trialkoxysilane, such as phenyltrialkoxysilane, and optionally a boron-containing material, such as boric acid, and optionally a catalyst, to the first mixture to form a second mixture, provided that at least one of the first and second mixtures includes a metal containing material or a boron- containing material; allowing the second mixture to react under agitation at a predetermined temperature to form a third mixture comprised of a metallosiloxane, borosiloxane, or borometalosiloxane resin, an alkyl alcohol, and optionally the solvent; removing the alkyl alcohol from the third mixture; optionally stripping the solvent away from the metallosiloxane, borosiloxane, or borometalosiloxane resin; and optionally forming a powder or flakes out of the metallosiloxane, borosiloxane, or borometalosiloxane resin. The method may be optionally performed with at least one of the steps being done under an inert atmosphere and the resin may optionally be phosphorylated.

[0006] According to one aspect of the present disclosure the step of providing an alkoxysilane intermediate may involve combining 9, 10-dihydro-9-oxa-10- phosphaphenanthrene-10-oxide (DOPO), an unsaturated alkoxysilane, and a free radical initiator in a solvent to form a first mixture. This first mixture is allowed to react at a temperature of 1 10°C or more, alternatively between 120°C and 140°C, to form a (DOPO- alkyl)trialkoxysilane intermediate. In this instance, the resin formed by the method is a phosphorous-containing borosiloxane (Si-P-B) resin; alternatively, a boro-(6H-dibenz[c,e] [1 ,2]oxaphosphorin,6-[2-(trialkoxysilyl)alkyl]-,6-oxide)-siloxane resin.

[0007] According to another aspect of the present disclosure the step of forming the first mixture is performed such that the addition rates of the reactants are controlled in a manner so that the amount of DOPO present in the first mixture is greater than the amount of unsaturated alkoxysilane. The optional solvent that is used may be either an aromatic or nonaromatic solvent. An example of an optional aromatic solvent, an unsaturated alkoxysilane, a free radical initiator, and an optional catalyst that may be used according to the teachings of the present disclosure is xylene, a vinylalkoxysilane (including but not limited to vinyltriethoxysilane, VTES), 2,5-Bis(ferf-butylperoxy)-2,5-dimethylhexane, and aqueous HCI, respectively. The (Si-P-B) resin formed may be a boro-(6H- dibenz[c,e][1 ,2]oxaphosphorin,6-[2-(triethoxysilyl)ethyl]-,6-oxide)-siloxane resin.

[0008] According to another aspect of the present disclosure, the first mixture is allowed to react until the reaction is complete as defined by the absence of a P-H absorption and the presence of a P-C absorption in an infrared spectroscopic measurement or by the absence of a peak or signal associated with a vinyl group in a nuclear magnetic resonance measurement. The infrared spectroscopic or nuclear magnetic resonance measurement may be obtained using an in situ reaction monitoring technique.

[0009] The predetermined temperature at which the second mixture is allowed to react is greater than the boiling point of the alkyl alcohol and less than the boiling point of the aromatic solvent present in the slurry. Alternatively, the predetermined temperature at which the second mixture is allowed to react is between 80°C and 138°C. The second mixture is allowed to react until the reaction is complete as defined by the formation of an alkyl alcohol from the reaction of the second mixture ceasing to occur. One or more of the reactants in the first or second mixtures can be combined in a stoichiometric amount. The resin is suspended in the third mixture formed by the reaction of the second mixture through the use of continuous agitation.

[0010] According to yet another aspect of the present disclosure, the resin is formed into a powder or flakes using a process that involves spray drying, pulverizing, crushing, chopping, cutting, flattening, or peeling performed with or without chilling. Alternatively, the resin is formed into a powder or flakes using a twin screw extruder or a blade mixer. Optionally, the process through which the resin is formed into a powder or flakes is performed under vacuum.

[001 1] The present disclosure also provides a phosphorous-containing borosiloxane (Si- P-B) resin, a metallosiloxane resin, a borosiloxane resin, or a borometalosiloxane resin for use as a flame retardant additive in a plastic or polymer composite; wherein the resin is prepared according to the method described herein. The resin prepared according to the method described herein is halogen-free.

[0012] Another aspect of the present disclosure describes a use for the Si-P-B, metallosiloxane, borosiloxane, or borometalosiloxane resin prepared according to the method defined herein. The resin can be used as a halogen-free, flame retardant additive in a plastic or polymer composite. Such a plastic or polymer composite can find use in a variety of automotive, rail transport, aerospace, or electronic applications. One specific example of a plastic or polymer composite is a transparent polycarbonate composite.

[0013] 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.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

[0015] Figure 1 is a schematic of a multiple step method for forming a metallosiloxane, borosiloxane, or borometalosiloxane resin according to the teachings of the present disclosure;

[0016] Figure 2 is a schematic representation of the reaction vessel used to form a first mixture that is allowed to react in order to prepare a (DOPO-alkyl)trialkoxysilane intermediate according to the 1^st step in the method of Figure 1 ; [0017] Figure 3 is a schematic representation of the reaction vessel used to form a second mixture that is allowed to react in order to prepare a resin according to the 2^nd step in the method of Figure 1 ;

[0018] Figure 4 is a schematic representation of the equipment used to prepare flakes from the resin according to the optional 3^rd step in the method of Figure 1 ; and

[0019] Figures 5 is a schematic representation of the equipment used to prepare a powder from the resin according to the optional 3^rd step in the method of Figure 1.

DETAILED DESCRIPTION

[0020] The following description is merely exemplary in nature and is in no way intended to limit the present disclosure or its application or uses. It should be understood that throughout the description, corresponding reference numerals indicate like or corresponding parts and features.

[0021] The present disclosure generally relates to a method of making a metallosiloxane, borosiloxane, or borometalosiloxane resin, alternatively, a phosphorylated resin, such as a phosphorous-containing borosiloxane (Si-P-B) resin, and use thereof. The resin made and used according to the teachings contained herein is described throughout the present disclosure as a halogen-free flame retardant additive used in conjunction with a plastic or polymer composite in order to more fully illustrate the concept. The incorporation and use of this resin in conjunction with other types of materials is contemplated to be within the scope of the disclosure.

[0022] Referring to Figure 1 , a method 100 of making the metallosiloxane, borosiloxane, or borometalosiloxane resin, optionally phosphorylated, is disclosed that includes two general steps and optionally a third step. The first step 125 involves providing a first mixture 130 comprising an alkoxysilane intermediate, optionally a solvent, and optionally a metal-containing material; wherein the alkoxysilane intermediate is capable of forming at least one Si-O-Metal or Si-O-B bond. The solvent may be selected as being either an aromatic or nonaromatic solvent. One specific example of an alkoxysilane intermediate, among others, is a (9, 10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide, alkyl)trialkoxysilane intermediate, also known as a (DOPO-alkyl)-trialkoxysilane intermediate, such as (9, 10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide, ethyl)triethoxysilane intermediate, also known as a (DOPO-ethyl)-triethoxysilane intermediate. One skilled in the art will understand that other anologs to DOPO-alkyl functionality, such as DOPO-hydroquinone can be used without exceeding the scope of the present disclosure.

[0023] The second step 150 involves the formation of a second mixture 155 by combining an alkyl- or aryl-trialkoxysilane, such as phenyltrialkoxysilane, and optionally a boron-containing material, and optionally a catalyst with the first mixture to form a second mixture and allowing said second mixture to react to form a third mixture 160 comprising the metallosiloxane, borosiloxane, or borometalosiloxane resin, an alkyl alcohol, and optionally the solvent. At least one of the first and second mixtures includes a metal- containing material or a boron-containing material. The optional third step 175 involves optionally removing the solvent and forming a powder or flakes out of the metallosiloxane, borosiloxane, or borometalosiloxane resin.

[0024] In the first step 125, the alkoxysilane intermediate may include any alkoxysilane capable of forming at least one Si-O-Metal bond or Si-O-B bond. Although the following disclosure provides a specific example of the alkoxysilane intermediate as being a (DOPOalkly)trialkoxysilane intermediate in order to form a phosphorous-containing borosiloxane (Si-P-B) resin, one skilled in the art will understand that other alkoxysilane intermediates may be used in conjunction with a metal-containing material or boron- containing material in order to form the metallosiloxane, borosiloxane, or borometalosiloxane resin without exceeding the scope of the present disclosure. Such other alkoxysilane intermediates may include, but not be limited to, tetra(alkoxysilane) Si(OR)₄, trialkoxysilane R'Si(OR)₃, dialkoxysilane R'₂Si(OR)₂ or monoalkoxysilane R'₃SiOR₃, or a mixture thereof, where R is a C1 to C10 alkyl group and each R' is independently selected as an alkyl, alkenyl, aryl, or arylalkyl group or another organic functionality, such as but not limited to glycidoxy, methacryloxy, and acryloxy.

[0025] The optional metal-containing material that may be present in the first step 125, is generally defined by the formula M(Z)_m where m =1-7 depending upon the oxidation state of the metal, M. In this formula Z is selected to be either an alkoxymetal compound where Z=OR"' and R'" is an alkyl group, or a metal hydroxyl compound, where Z=OH. Metal halide compounds, where Z=CI or Br are preferably avoided in order to ensure that the product of the reaction is halogen free. For specific example, when M is aluminum, the alkoxymetal can be for example AI(OEt)₃ or AI(OPr)₃ where Et and Pr are ethyl and propyl groups, respectively.

[0026] In the 2^nd step 150 of the method 100 as shown in Figure 1 , an alkyl- or aryl- trialkoxysilane, and optionally a boron-containing material, and when desirable a catalyst are combined with the first mixture to form a second mixture. At least one of the first and second mixtures includes a metal-containing material or a boron-containing material. One specific example of an aryl-trialkoxysilane that may be used in this 2^nd step 150 is phenyltrialkoxysilane. The optional boron-containing material may be selected from (i) boric acid having the formula B(OH)₃, any of its salts or boric anhydride, (ii) boronic acid having the formula R^ivB(OH)₂, (iii) alkoxyborate having the formula B(OR^iv)₃ or R^ivB(OR^iv)₂, or a mixture thereof, where each R^IV is independently selected to be an alkyl, alkenyl, aryl or arylakyl group. Alternatively, the boron-containing compound is boric acid.

[0027] Various alkoxysilane intermediates, metal-containing compounds, and boron- containing compounds suitable for use herein are described in additional detail along with the structure and composition of the metallosiloxane resins, borosiloxane resins, or borometalosiloxane resins formed therefrom in three co-pending International Patent Applications No.'s PCT/US12/065059, PCT/US12/065010, and PCT/US 12/065024 (each filed on November 14, 2012), the entire contents of which are hereby incorporated in their entirety by reference.

[0028] In order to further describe method 100, a phosphorous-containing borosiloxane (Si-P-B) resin is prepared although one skilled in the art will understand that the method 100 may be used to form other borosiloxanes, metallosiloxanes, and borometalosiloxanes without exceeding the scope of the disclosure. In the preparation of Si-P-B resin, 9,10- dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO) is mixed 135 with an unsaturated alkoxysilane, alternatively a vinyltrialkoxysilane, alternatively, vinyltriethoxysilane (VTES), a free-radical initiator, and an aromatic solvent to form the first mixture. The addition rates of the reactants are controlled in a manner so that the amount of DOPO present in the first mixture is greater than the amount of unsaturated alkoxysilane. The first mixture is allowed to react 140 at about 1 10°C or more to form a (DOPOalkly)trialkoxysilane intermediate; alternatively, the reaction temperature is between 120°C and 140°C. The reaction time at a reaction temperature of 120°C is on the order of about 10-12 hours, while the reaction time conducted at 130°C is less than about 3 hours. The reaction time can further be reduced by increasing the reaction temperature to 140°C. This reaction is highly exothermic in that it is capable of releasing about 135 KJ of heat per mole reacted. The rate of this reaction increases rapidly at higher temperatures, and as the rate of the reaction increases, higher amounts of heat are subsequently released. This further increases the reaction temperature and corresponding reaction rate. This chain of events can quickly lead to a potentially explosive, run-away reaction. In order to prevent a run-away reaction, several process variables need to monitored and controlled when this reaction is run at production scale quantities.

[0029] Referring now to Figure 2, in forming the first mixture 135, the 9,10-dihydro-9-oxa- 10-phosphaphenanthrene 10-oxide (DOPO) reactant 136 is added first to the reaction vessel 201. The reaction vessel 201 is equipped with a mixer 202 and a condenser 203, as well as jacketed 204 in order to provide for even heat distribution 205. At least one of the steps may optionally be conducted under an inert atmosphere. In other words, the oxygen from the reaction vessel may be removed and replaced with an inert nitrogen atmosphere 141. Then an aromatic solvent 137 is fed into the reactor to form a DOPO/aromatic solvent mixture that comprises between about 30-50% DOPO by weight. The DOPO reactant 136 is introduced into the reaction vessel 201 prior to the addition of the aromatic solvent 137 in order to avoid static build up in the presence of a flammable solvent. The DOPO/aromatic solvent mixture is then heated 205 to a reaction temperature that is about 1 10°C or more, alternatively about 130°C, which causes the two phase mixture to transition to a homogenous solution. This reaction temperature also provides for a reasonably fast, yet controllable reaction with the vinyltrialkoxysilane 138.

[0030] Alternatively, one skilled in the art will understand that the order of addition of the DOPO reactant 136 and solvent 137 to the reaction vessel 201 may be different than described above without exceeding the scope of the present disclosure, For example, if specific equipment designed for the safe handling of solids or powders to flammable liquids is utilized, the DOPO reactant 136 could be added to the reaction vessel 201 after the solvent 137 is already in the vessel 201. One skilled in the art will further understand that the use of a solvent, such as an aromatic solvent, is optional when some reaction vessels, such as a tube reactor or a micro-reactor, are used.

[0031] Still referring to Figure 2, before adding the unsaturated alkoxysilane 138 to the homogeneous solution, it is first mixed with a free-radical initiator 139, so that the free- radical initiator is present in about 0.1 wt.% to about 5 wt.%; alternatively, about 0.5 wt.% to 3 wt.%; alternatively, 1 wt.% to 2 wt.%. The unsaturated alkoxysilane / free radical initiator mixture is then added to the homogenous solution to form the first mixture 135. As another part of the 1^st step 125, the first mixture is allowed to react 140 at the reaction temperature to form a (DOPOalkyl)trialkoxysilane intermediate. The concept is to add the unsaturated alkoxysilane at a slow enough rate to avoid concentrations reaching a level that could result in a runaway reaction. A secondary benefit is to avoid excess unsaturated alkoxysilane in the product which would detract from the flame retardant properties.

[0032] Still referring to Figure 2, the unsaturated alkoxysilane / free radical mixture is fed into the heated homogeneous solution while monitoring both reaction temperature and reaction progress. The progress of the reaction is monitored using an in situ infrared (IR) spectroscopic 206 or nuclear magnetic resonance (NMR) spectroscopic 207 measurement technique. This method 100 allows isolation of the reactive unsaturated groups, alternatively, vinyl groups, from heat until the moment initiation is desired, thereby, providing temporal control of reaction initiation. The first mixture is allowed to react until the reaction is complete as defined by the absence of a P-H absorption and the presence of a P-C absorption in an infrared spectroscopic measurement or by the absence of a peak or signal associated with a vinyl group in a nuclear magnetic resonance measurement. By monitoring the reaction with in situ IR or NMR spectroscopy 206, 207 it is possible to control the exothermic reaction by limiting the reactive unsaturated groups that are available by feeding the unsaturated alkoxysilane / free radical mixture into the reactor 201 at the same rate at which the vinyl groups are consumed. The hazardous build-up of vinyl groups in the presence of peroxide can thus be avoided. Thus this method 100 entails a process control strategy for reactions where accumulation of a highly reactive species needs to be carefully controlled. This strategy is applicable to improving process safety and control of other types of reactions, including hydrosilylation reactions, without exceeding the scope of this disclosure.

[0033] By conducting the reaction in a solvent 137 the magnitude of the heat given off during the exothermic reaction is minimized and easily maintained at a safe level. The solvent 137 may be either an aromatic solvent or a nonaromatic solvent. Alternatively, the solvent 137 is an aromatic solvent; alternatively, the aromatic solvent is toluene, ethyl benzene, xylene, or mixed xylenes; alternatively, the aromatic solvent 137 is xylene or mixed xylenes. The solvent 137 serves as a heat sink as well as a reaction medium. Depending upon which solvent is selected for use, the reaction vessel may be at a reduced pressure, atmospheric pressure, or an elevated pressure. With a boiling point of ~138.5°C, xylene, when used as the solvent, provides additional safety with the ability to dissipate heat through evaporative cooling. While this reaction can easily be maintained below reflux temperature (~140°C) if it is desired for product quality reasons, e.g. color, running the reaction at reflux temperature simplifies material additions and temperature control at the plant scale. This method has proven effective to produce the (DOPOalkyl)trialkoxy silane intermediate with improved safety and selectivity of desired chemical structure.

[0034] Any commercially available free radical initiator 139 known to one skilled in the art may be utilized. One example of such a free radical initiator 139 is 2,5-Bis(ferf- butylperoxy)-2,5-dimethylhexane (Luperox® 101 , Sigma-Aldrich Corp., St. Louis, MO). The use of Luperox® 101 is advantageous for its relatively high stability at lower temperatures as well as high reactivity due to high yields of free radical species at elevated temperatures. Unlike many other free radical initiators, Luperox® 101 is a liquid, which has significant advantages with regards to safe handling in production scale reactions by avoiding the need for special solids handling equipment specified for a flammable environment.

[0035] Referring once again to Figure 1 , in the second step 150 a slurry or third mixture of a metallosiloxane, borosiloxane, or borometalosiloxane resin, an alkyl alcohol, and optionally the solvent is formed 160. One specific example of a resin formed is a boro-(6H- dibenz[c,e][1 ,2] oxaphosphorin,6-[2-(trialkoxysilyl)alkyl]-,6-oxide)-siloxane (Si-P-B Resin), such as boro-(6H-dibenz[c,e][1 ,2] oxaphosphorin,6-[2-(triethoxysilyl)ethyl]-6-oxide)- siloxane, This Si-P-B resin is synthesized by mixing together the (DOPOalkyl)trialkoxysilane intermediate from the first step 125, with a boron-containing material, such as boric acid, and an alkyl- or aryl-trialkoxysilane, such as phenyltrialkoxysilane, as well as an optional catalyst to form 155 a second mixture. Alternatively, the phenyltrialkoxysilane is phenyltrimethoxysilane and the optional catalyst is aqueous HCI. The catalyst when present is added in an amount equivalent to about 0.5 wt.% to about 5 wt.%, alternatively, about 1 .5 wt.% to about 4 wt. %, alternatively, about 3 wt.% based on the weight of the second mixture. During this second step 150, the second mixture is allowed to react under agitation and at a predetermined temperature to form 160 a slurry that is comprised of the Si-P-B resin, at least one alkyl alcohol, and optionally the solvent. Examples of the alkyl alcohols include but are not limited to ethyl alcohol and methyl alcohol. To avoid the reverse reaction, and loss of molecular weight, with corresponding reduction in flame retardant performance, the alkyl alcohol(s) are removed 165 from the reaction. The boric acid is added last in forming the second mixture because a complete reaction assists in ensuring that less than 5 wt.% boric acid will remain in the final product.

[0036] The predetermined temperature at which the second mixture is allowed to react is greater than the boiling point of the alkyl alcohol and less than the boiling point of the solvent if present in the slurry. Alternatively, the predetermined temperature at which the second mixture is allowed to react is between about 80°C and about 138°C. The second mixture is allowed to react until the reaction is complete as defined by the absence of any further alkyl alcohol in the slurry being generated or arising from the reaction of the second mixture. When desirable, one or more of the reactants in the first or second mixtures are added in a stoichiometric amount; wherein a stoichiometric amount refers to all of the reagent being consumed in the reaction or no excess of the reagent remains after the reaction is complete.

[0037] When present, removing all solvent in the reactor at this stage 180, however, would yield a glassy, solid, resin that could not be easily transferred. To enable transfer of the resin for further processing in the 3^rd step 175, the resin must remain in the solvent . The Si-P-B resin is suspended or maintained in the slurry formed by the reaction of the second mixture by the use of continuous agitation until any solvent that may be present is removed or stripped 180 away from the Si-P-B resin in the 3^rd step 175 of the method 100. The Si-P-B resin is then further processed by causing the resin to take the form 185 of either a powder or flakes. [0038] Various compositions of Si-P-B resins can be formed according to the teachings of the present disclosure. Alternatively, the Si-P-B resin formed is described as boro-(6H- dibenz[c,e][1 ,2]oxaphosphorin,6-[2-(trialkoxysilyl)alkyl]-,6-oxide)-siloxane. The composition of Si-P-B resins are described and discussed in further detail in co-pending International Patent Application No. PCT/US 12/065059 (filed November 14, 2012), the entire contents of which is, hereby, incorporated by reference.

[0039] Referring to Figures 2 and 3, the Si-P-B manufacturing method 100 utilizes multiple types of reaction vessels and equipment. The first reaction vessel is an agitated 202, temperature jacketed 204 (rated for at least 140^°C) kettle 201 outfitted with both liquids and solids handling capabilities. A condenser 203 capable of refluxing the solvent, as well as conducting solvent stripping is also required. This equipment is responsible for the synthesis of the Si-P-B resin and removal of all alcohols generated from the reaction.

[0040] One skilled in the art will understand that other types of reaction vessels could be used in place of the kettle 201 described herein without exceeding the scope of the current disclosure. For example, a tube reactor, a micro-reactor, or a pressure reactor could be utilized. In the case of the tube reactor or micro-reactor, when desirable the reaction could be run without a solvent being present. In the case of the pressure reactor, a nonaromatic or aromatic solvent could be used that may be the same or different than the solvent selected for use in the reaction vessel or kettle 201 described herein.

[0041] The manufacturing method or process 100 is capable of making a range of different Si-P-B resin formulations. Typically, the ranges associated with the different constituents in the boro-DOPO-siloxane component are about 40-70 mole % boron, about 10-40 mole % Si-DOPO, and about 10-30 mole % Si-Phenyl. Aromatic on nonaromatic hydrocarbons are used as the carrier solvent because of the difference in their boiling point relative to alkyl alcohols. In addition these solvents, unlike alcohols, do not affect the Si-P- B resin stability.

[0042] Referring now to Figure 3 and Figure 1 , the 2^nd step 150 of the method 100 may utilize the same reaction vessel 201 as used in the 1 ^st step 125 or a different reaction vessel. The process 100 and the process equipment remains the same for the preparation of each of the various Si-P-B resin formulations possible. In the 2^nd step 150, an alkyl- or aryl-alkoxysilane 157, such as phenyltrialkoxysilane, alternatively, phenyltrimethoxysilane, and (DOPOalkoxy)trialkoxysilane intermediate 140, and optionally boric acid 156 and/or a catalyst 159 are loaded and agitated 202 in the kettle 201 , along with a predetermined amount of a catalyst to form 155 a second mixture 158. The second mixture 158 is then heated 205 between about 120-140^°C using the jacketed 204 reaction vessel 201 and allowed to react 160. As a result of this reaction 160, alcohols (e.g., methanol and ethanol) are formed and are continuously refluxed back into the kettle 201. The kettle 201 contents will equilibrate between about 85-1 10^°C as a result of the cooling effects of the refluxing alcohols. After the allotted reaction time, about 3-10 hours after the contents of the kettle reach a stable temperature, the alcohols can be removed 165 from the kettle 201. As the alcohols are removed, the kettle contents will rise in temperature until they reach the jacket temperature. A brief hold at this temperature will allow for any residual alcohols to be stripped or removed, which is essential to ensure the stability of the Si-P-B resin before the final processing. After this 2^nd step 150 has been completed, the resin and optional solvent mixture 159 will be transferred to the final stripping unit in the 3^rd step 175.

[0043] It is beneficial to continuously agitate 202 the vessel 201 as the resin is formed. The Si-P-B resin is only somewhat soluble in the solvent and therefore will precipitate out during the reaction. Continuous agitation helps prevent the resin from settling out and making a tacky layer on the bottom of the kettle 201. Keeping the resin and optional solvent as a slurry allows for it to be more easily transferred (i.e., drum-off or piping) to the final processing step 175.

[0044] Referring once again to Figure 1 , the optional 3^rd step 175 includes the removal or stripping 180 of any solvent from the boro-(6H-Dibenz[c,e][1 ,2]oxaphosphorin,6-[2- (trialkoxysilyl)alkyl]-,6-oxide)-siloxane (Si-P-B) resin, followed by the final step of the finishing process of forming 185 the Si-P-B resin into either a powder or flakes. The Si-P-B resin cannot be easily processed unless it is in a carrier solvent. Furthermore, the solvents used in processing are themselves flammable and should be removed in the final resin product in order to obtain an effective flame retardant product. The resin may take the form of a flake or powder. As with the 1^st step 125 and 2^nd step 150, this can be accomplished easily in small lab-scale glassware. However, processing the resin into final solid form poses many challenges for a larger production volume, including plugging of the equipment that results in a lengthy and costly clean-out procedure.

[0045] The Si-P-B resin is formed into a powder or flakes using a process that involves spray drying, pulverizing, crushing, chopping, cutting, flattening, or peeling performed with or without chilling. Optionally, the process through which the Si-P-B resin is formed into a powder or flakes is performed under vacuum. Referring now to Figure 4, one example of a process of making flakes 185a out of the Si-P-B resin involves the use of a twin screw extruder (TSE) 300, equipped with heating elements, feed pumps, and a vacuum system. The TSE 300 requires multiple vacuum ports, along with a simple screw design based on the vacuum port locations, and the ability to operate at high temperatures. Accompanying the TSE 300 is a cooled flaking unit 305 equipped with a product collector. This equipment 300 is used to strip the carrier solvent 310, cool the Si-P-B resin and produce solid flakes 185a ready for packaging.

[0046] During the operation of the twin screw extruder 300 the material transferred from the 2^nd step 150 is agitated in order to ensure that the precipitated Si-P-B resin is carried into the twin screw extruder 300. Si-P-B resin in the optional solvent is fed, via a pump (a gear pump presumably), into the extruder 300. In order to make start-up smoother, pumping a 50,000+ centistoke polymer into the extruder initially, then gradually slowing down the polymer feed rate while increasing the Si-P-B resin / optional carrier solvent feed rate will help the solvent stripping from the Si-P-B resin and solvent mixture reach a steady state quicker because the polymer initially helps create a seal, which helps draw material down the TSE 300 and aids in pulling a vacuum. The operating conditions of the heating zones 315 can range from 80-200^°C. Alternatively, the heating 315 is conducted in a gradient heating pattern. Increasing the heat 315 from 80-160^°C in 20^°C increments is one specific example of a gradient heating pattern. Multiple vacuum zones allow for a more gradual, and complete, solvent removal while allowing the resin to remain flowable. In this process, the solvent is condensed and trapped. A basic screw design, with minimal kneading and back mixing, can be used. Excess shear and heat is avoided as it will facilitate bodying of the resin and potentially cause plugging of the twin screw extruder 300. The extruded Si-P-B resin proceeds to fall into a cooled flaking unit where the Si-P-B resin is solidified and broken apart into flakes followed by collection/packaging. The amount of residual solvent present in the Si-P-B resin flakes is less than about 0.30 wt.%, alternatively, less than about 0.20 wt.%, alternatively, less than about 0.10 wt.%.

[0047] Referring now to Figure 5, one specific example of forming a powder 185b out of the Si-P-B resin involves the use of a sigma-blade mixer 400 (Baker-Perkins Ltd, United Kingdom) equipped with the heating elements, feed pumps, and a vacuum system. This mixer 400 is used to strip the carrier solvent 410 and pulverize the solid Si-P-B resin into a solvent free powder 185b ready for packaging.

[0048] The Si-P-B resin in solvent is loaded and sealed into the mixer 400. The sigma- blade mixer is heated 415 between 100-160^°C with vacuum being gradually applied. As solvent is removed 410, it is condensed and trapped. As the Si-P-B resin loses solvent it becomes very viscous and then brittle. The high torque blades 420 of the mixer 400 are designed to handle this phase and assist in continuing to facilitate the solvent strip 410. As the solvent content nears ppm levels, the solid, brittle resin is broken apart and pulverized by the mixer's blades 420. As a result of this, a solid, Si-P-B resin powder 185b is formed ready for packaging. [0049] According to another aspect of the present disclosure a phosphorous-containing borosiloxane (Si-P-B) resin prepared according to the previous described methodology is disclosed along with its use as a flame retardant additive in a plastic or polymer composite. This Si-P-B resin is used in such composites because it is halogen-free. The plastic or polymer composite comprising the Si-P-B prepared according to the method described in this disclosure can be used in a variety of automotive, rail transport, aerospace, or electronic applications.

[0050] The composition of the plastic or polymer composite may comprise polycarbonate, polyamide, polyester, epoxy, polyolefin (e.g. polypropylene or polyethylene), a bio-sourced thermoplastic matrix, such as polylactic acid (PLA) or polyhydroxybutadiene (PHB), or bio-sourced polypropylene or polyethylene. The polymer may also be a thermoplastic/rubber blend or a rubber made of a diene, alternatively natural rubber. Alternatively, the plastic or polymer composite is a transparent polycarbonate composite.

[0051] The following specific embodiments are given to illustrate the use of method 100 according to the teachings of the present disclosure and should not be construed to limit the scope of the disclosure. Those skilled-in-the-art, in light of the present disclosure, will appreciate that many changes can be made in the specific embodiments which are disclosed herein and still obtain alike or similar result without departing from or exceeding the spirit or scope of the disclosure. One skilled in the art will further understand that any properties reported herein represent properties that are routinely measured and can be obtained by multiple different methods. The methods described herein represent one such method and other methods may be utilized without exceeding the scope of the present disclosure.

[0052] Example 1 - Synthesis of (9,10-dihydro-9-oxa-10-phosphaphenanthrene 10- oxide, ethyl)triethoxysilane((DOPOethyl)triethoxysilane) intermediate

[0053] A total of 759 g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO) is added to a 5 L reaction vessel. After purging with nitrogen, 1500 g xylene solvent is fed to the reactor to form a slurry, consisting of -34 wt.% DOPO in xylene. The DOPO powder is fed prior to the xylene in order to avoid static build up in the presence of a flammable solvent. The DOPO powder may be fed into the reactor after the xylene, provided solids metering equipment designed for the safe transfer of a powder into a flammable liquid is utilized. The two-phase system is heated, transitioning to homogeneous solution when the temperature reaches 70°C. The solution is further heated to the desired reaction temperature of 130°C. [0054] Xylene solvent was selected for the reaction medium in this Example because it provides a heat sink to help control the temperature of the reaction while remaining inert to the chemistry involved. The xylene exhibits a sufficiently high boiling point to allow the reaction to be carried out at the temperature required for economical production without boiling and while operating under atmospheric conditions. Furthermore, xylene has proven to be an effective medium for downstream production steps to make the Si-P-B resin from the DOPOethoxy-xylene intermediate. These steps require a solvent exchange from ethanol and methanol, which destabilize the resin, to a solvent that is inert to the resin chemistry. Still, the solvent provides sufficient solubility to mediate the reaction.

[0055] In a separate flask 667 g vinyltriethoxysilane (VTES) is mixed with 1 1.7 g of the free-radical initiator, 2,5-Bis(ferf-butylperoxy)-2,5-dimethylhexane (Luperox 101 ). Luperox 101 is selected for use in this Example from numerous commercially available free radical initiators for its relatively high stability at lower temperatures as well as high reactivity due to high yields of free radical species at elevated temperatures. Unlike many other free radical initiators Luperox101 is a liquid, providing significant advantages such as safer handling at plant scale by avoiding the need for special solids handling equipment specified for a flammable environment.

[0056] The VTES/Luperox101 solution is fed to the heated DOPO/xylene slurry while reaction temperature and reaction progress are monitored using in situ infrared spectroscopy (IR). This method allows isolation of reactive vinyl groups from heat until the moment initiation is desired, providing temporal control of initiation. By monitoring the reaction with in situ IR it is possible to perfectly control the exotherm by limiting reactive species available and feeding at the rate consumed. IR and NMR analysis confirmed that the desired chemical structure is obtained using this process. A total of 2922 g of DOPO- silane product in xylene solution is collected and stored for later use in the DOPO resin synthesis step described in Example 3.

[0057] Example 2 - Synthesis of (9, 10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide, ethyl)triethoxysilane((DOPOethyl)triethoxysilane) intermediate at reflux temperature

[0058] The process of Example 1 is run again with the main difference being an increase in the reaction temperature used in this experimental run to be about the same as the reflux temperature for the solvent. With a boiling point of 138.5°C, xylene provides additional safety with the ability to dissipate heat through evaporative cooling. While this reaction can easily be maintained below reflux temperature (140°C), as described in Example 1 , if it is desired for product quality reasons, e.g. color, running the reaction at or near the solvent's reflux temperature simplifies material additions and temperature control at the plant scale. In situ infrared spectroscopy (IR) is utilized to verify consumption of vinyl groups to avoid the potentially hazardous build-up of energetic material. Running at the reflux temperature simplified the control strategy since the temperature cannot exceed 140°C as long as xylene is present. The ease of maintaining this reaction temperature allows the focus to shift to simply controlling the rate of addition of VTES/Luperox101 to the reaction. IR and NMR analysis confirms that the desired chemical structure is obtained using this process. The DOPO-silane product in xylene solution is collected and stored for later use.

[0059] Example 3 - Synthesis of the Si-P-B Resin

[0060] A total of 2449 grams of (DOPOethyl)triethoxysilane intermediate in xylene from Example 1 is initially added to an inert, five liter reaction vessel equipped with an agitator, condenser, Dean-Stark trap, and nitrogen purge. The agitator is initially turned on low to allow for a slow mix of the reactor contents as 538 grams of phenyltrimethoxysilane is added, followed by 335 grams of solid boric acid and 4.5 grams of 15N HCI in 55 grams of deionized water solution. This was done to ensure the boric acid remained in the slurry instead of settling out. The reactor jacket on the vessel is then set to 130°C. As the reactor temperature approached 60-70°C, the alcohols (methanol and ethanol) began to form and reflux as the reaction began. At this point, the slurry becomes more homogeneous as the boric acid is consumed by the reaction. As the reactor approaches 75-85°C, more specifically about 81 °C, a heavy reflux of the by-product alcohols is observed to occur. The reaction is allowed to proceed for about three hours. The reactor remains at the reflux temperature for the duration of the reaction due to the cooling effect of the refluxing alcohols. After the three-hour hold time, the refluxing alcohols are trapped and removed using the Dean-Stark trap. As the alcohols are removed, the temperature inside the reactor rises and approaches the jacket set point of 130°C. When the reactor contents reach the 100-120°C range, very minimal reflux is observed as the alcohol/xylene solvent exchange is nearly complete. Once the reactor temperature reaches 120-130°C, another 5-10 minutes of reflux trapping is carried out to ensure the complete removal of the alcohols. The reactor is then cooled while being agitated. Some of the Si-P-B resin precipitates from solution and is collected at the bottom of the reactor vessel. Although tacky, the precipitated resin flows with the rest of the solution. The DOPO-resin in xylene is then removed from the reactor and sent to be stripped to the final product as described in Example 4.

[0061] Example 4 - Si-P-B Resin Extrusion Through Twin Screw Extruder (TSE)

[0062] A solid, white flake/powder is the desired final product. In order to produce this form of the Si-P-B resin, a twin screw extruder (TSE) is used to strip the carrier xylene followed by a flaking unit to produce the solid Si-P-B resin. Several batches of the Si-P-B resin, such as those produced in 5 L reactors in Examples 1 and 2, are combined into an agitated 5 gallon pail. An agitated feed tank assists in keeping the precipitated Si-P-B resin in a relatively uniform slurry in order to feed the TSE.

[0063] The TSE utilized in this Example has 1 1 barrels. The Si-P-B resin slurry is fed into barrel 1 using a gear pump and stripped throughout the length of the screw. More specifically, four vacuum ports, located at barrels 2, 4, 6, and 9, remove the xylene with most of the solvent removal being done through barrel 6. The temperature profile through the TSE involves temperatures less than about 200°C. In addition, a temperature gradient is utilized to keep xylene with the resin as long as possible in order to establish seals in the vacuum ports and to decrease the shear exerted in order to prevent the Si-P-B resin from bodying (i.e., gelling, etc.) as much as possible. Excess temperature, along with the accompanying shear exerted of the screws, causes the Si-P-B resin to body, which can plug the TSE. The temperature profile utilized in the TSE of this Example is shown below in Table 1. In order to decrease the possibility of bodying the Si-P-B resin due to the exerted shear, a simple screw design is used in the TSE. With the exception of under the barrels having vacuum ports, all conveying elements in the TSE are used because a long residence time is not necessary. Kneading and back mixing elements are conservatively placed beneath each vacuum port.

[0064] Table 1 - Basic Twin Screw Extruder Set-Up and Temperature Profile

[0065] The stripped Si-P-B resin flows out of the extruder and is immediately fed into a chilled flaking unit. Large rollers in the chilled flaking unit grab, flatten, and cool the resin before breaking the pieces apart into palm-sized flakes. The solid, white Si-P-B resin flakes are then collected and packaged. Samples of the flaked resin are submitted for analysis using solid state ²⁹Si, ¹³C and ¹¹B NMR to ensure the correct formulation and to evaluate the free boric acid content, headspace gas chromatography (GC) to measure residual xylene content, and thermal gravimetric analysis (TGA) to measure various physical and chemical phenomena associated with the flaked resin.

[0066] The foregoing description of various forms of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Numerous modifications or variations are possible in light of the above teachings. The forms discussed were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various forms and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.

Claims

CLAIMS What is claimed is

1. A method of making a metallosiloxane, a borosiloxane, or a borometalosiloxane resin, the method comprising the steps of:

providing a first mixture comprising an alkoxysilane intermediate, optionally, a solvent, and optionally a metal containing material; wherein the alkoxysilane intermediate is capable of forming at least one Si-O-Metal or Si-O-B bond;

combining an alkyl- or aryl-trialkoxysilane, and optionally a boron-containing material, and optionally a catalyst, with the first mixture to form a second mixture; wherein at least one of the first and second mixtures includes a metal containing material or a boron-containing material;

allowing the second mixture to react under agitation at a predetermined temperature to form a third mixture comprised of the metallosiloxane, borosiloxane, or borometalosiloxane resin, an alkyl alcohol, and optionally the solvent;

removing the alkyl alcohol from the third mixture; and optionally

stripping the solvent away from the metallosiloxane, borosiloxane, or borometalosiloxane resin; and optionally

forming a powder or flakes out of the metallosiloxane, borosiloxane, or borometalosiloxane resin.

2. The method of Claim 1 , wherein the metallosiloxane, borosiloxane, or

borometalosiloxane resin is phosphorylated.

3. The method of Claims 1 or 2, wherein the solvent is an aromatic or nonaromatic solvent and the predetermined temperature at which the second mixture is allowed to react is greater than the boiling point of the alkyl alcohol and less than the boiling point of the solvent.

4. The method of Claim 3, wherein the alkyl alcohol is removed from the third mixture as the alkyl alcohol is formed.

5. The method of Claim 4, wherein the second mixture is allowed to react until the reaction is complete as defined by the formation of an alkyl alcohol from the reaction of the second mixture ceasing to occur.

6. The method of any of Claims 1-5, wherein the predetermined temperature at which the second mixture is allowed to react is between 80°C and 138°C.

7. The method of any of Claims 1-6, wherein the method incorporates at least one of the solvent being xylene, the boron-containing material being boric acid, the metal- containing material being a metal hydroxide or an alkoxymetal compound, the alky- or aryl-alkoxysilane being phenyltrialkoxysilane, and the optional catalyst being aqueous HCI.

8. The method of any of Claims 1-7, wherein the alkoxysilane intermediate is formed by combining 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), an unsaturated alkoxysilane, and a free radical initiator in the solvent and allowing a reaction to occur at a predetermined temperature.

9. The method of Claim 8, wherein the DOPO and unsaturated alkoxysilane are

combined in a manner such that the amount of DOPO present is greater than the amount of unsaturated alkoxysilane present.

10. The method of Claims 8 or 9, wherein the step of providing a first mixture includes one or more of the following:

the solvent is xylene;

the unsaturated alkoxysilane is a vinylalkoxysilane, alternatively

vinyltriethoxysilane (VTES);

the free radical initiator is 2,5-Bis(ferf-butylperoxy)-2,5-dimethylhexane; and the predetermined temperature is defined as being in the range of 120°C to

140°C.

1 1. The method of any of Claims 8-10, wherein the first mixture is allowed to react until the reaction is complete as defined by the absence of a P-H absorption and the presence of a P-C absorption in an infrared spectroscopic measurement or by the absence of a peak or signal associated with an unsaturated group in a nuclear magnetic resonance measurement; optionally, the infrared spectroscopic or nuclear magnetic resonance measurement is obtained using an in situ reaction monitoring technique.

12. The method of Claims 1-1 1 wherein the resin formed is a Si-P-B resin;

alternatively, a boro-(6H-dibenz[c,e][1 ,2]oxaphosphorin,6-[2-(triethoxysilyl)ethyl]-, 6- oxide) -siloxane resin.

13. The method of Claims 1-12, wherein the metallosiloxane, borosiloxane, or

borometalosiloxane resin is formed into the powder or flakes using a process that involves spray drying, pulverizing, crushing, chopping, cutting, flattening, or peeling performed with or without chilling.

14. The method of Claim 13, wherein the process through which the metallosiloxane, borosiloxane, or borometalosiloxane resin is formed into the powder or flakes uses a twin screw extruder or a blade mixer.

15. A phosphorous-containing borosiloxane (Si-P-B ) resin, a metallosiloxane resin, a borosiloxane resin, or a borometalosiloxane resin for use as a flame retardant additive in a plastic or polymer composite; the resin being prepared according to the method of any of Claims 1-14.

16. The resin of Claim 15, wherein the resin is halogen-free.

17. The use of a phosphorous-containing borosiloxane (Si-P-B) resin, a metallosiloxane resin, a borosiloxane resin, or a borometalosiloxane resin as a halogen-free, flame retardant additive in a plastic or polymer composite; the resin being prepared according to the method of any of Claims 1-14.

18. A plastic or polymer composite for use in an automotive, rail transport, aerospace, or electronic application, the plastic or polymer composite including a phosphorous- containing borosiloxane (Si-P-B ) resin, a metallosiloxane resin, a borosiloxane resin, or a borometalosiloxane resin as a flame retardant additive; the resin being prepared according to the method of any of Claims 1-14.

19. The plastic or polymer composite of Claim 18, wherein the plastic or polymer

composite is a transparent polycarbonate composite.