Flame retardant masterbatch composition for foam containing pH adjuster

Abstract

1. A masterbatch composition suitable for use as a flame retardant in extruded polymer foams, a process for making the same, and an extruded foam containing the same, the composition comprising: (a) 20 to 40 parts by weight of a base resin comprising a styrene homopolymer or copolymer; (b) 1 to 16 parts by weight of an acid scavenger comprising an epoxy-based compound; (c) 2 to 6 parts by weight of an antioxidant comprising an alkyl phosphite or an aryl phosphite; and (d) 45 to 60 parts by weight of a flame retardant comprising a non-hexabromocyclododecane (HBCD) brominated polymer or copolymer, the amounts of (a), (b), (c), and (d) totaling 100 parts by weight; and the composition comprising (e) 0.6 to 10 parts by weight of a pH adjuster, based on 100 parts of the (a) base resin and the (e) water-soluble pH adjuster.

Description

[Technical Field]

[0001] The present invention relates to stabilized, environmentally friendly masterbatch compositions containing brominated polymeric flame retardants, particularly masterbatch compositions suitable for use in solid foams as additive compositions. [Background technology]

[0002] Various environmentally friendly brominated organic polymeric flame retardant (FR) compounds, such as those disclosed in U.S. Patent No. 9,663,649 to Kram et al., can be used to impart flame retardancy to solid foams, and the flame retardants can be incorporated into the foam using masterbatch compositions. However, the ultimate flame retardant performance of the brominated compounds in such foams can depend on the thermal stability of the bromine-carbon bonds. That is, these bonds must be sufficiently stable to withstand the temperatures encountered during various manufacturing processes that may be used in initially formulating the masterbatch composition, combining the masterbatch composition with a separate resin or foam composition, or even actually producing an article comprising a resin or foam composition containing the masterbatch composition. It is desirable that the brominated FR additive composition is not significantly adversely affected by these manufacturing steps, which may include exposure to temperatures exceeding 200°C. This helps ensure that the brominated FR additive composition functions as intended, i.e., retains sufficient bromine that can be released as active bromine-containing species when the final article containing the masterbatch composition experiences a thermal event (e.g., temperatures above 250°C) to facilitate flame suppression under fire conditions.

[0003] Typically, the processes for manufacturing masterbatch compositions or combining masterbatch compositions into resin or foam compositions are melt processes and occur in the organic phase. If the brominated FR additive is not sufficiently thermally stable, bromine can be liberated during these processes. This bromine can form acidic hydrogen bromide (HBr), which can corrode processing equipment, further catalytically decompose the FR additive, and raise worker exposure concerns. To mitigate this acid formation, organic-soluble acid scavengers, such as epoxy-based acid scavengers, are added to the brominated FR additive masterbatch composition to manage this acid in the organic phase.

[0004] However, in many final foam formulations, including those containing styrene-acrylonitrile (SAN) copolymers, water is used as a co-blowing agent. HBr has high mobility in the aqueous phase, and HBr can drive undesirable kinetics of the dehydrohalogenation reaction, including undesirable viscosity increase due to crosslinking of the SAN copolymer, also known as SAN hydrolysis. Summary of the Invention [Problem to be solved by the invention]

[0005] What is needed are water-soluble pH adjusters that can be included in brominated FR additive masterbatch compositions, that can withstand the melt process of making the masterbatch composition and further processing the masterbatch composition into a resin or foam composition, and that can further be utilized as a pH adjuster when water is present, particularly when water is used as a co-blowing agent to make foams. In particular, what is needed are water-soluble pH adjusters that do not adversely affect the foam formation process or the appearance of the resulting foam as evidenced by yellowness index; and that further slow the induction time of the kinetics of secondary chemical reactions in the foam composition as evidenced by the onset time of foam or masterbatch decomposition by thermogravimetric analysis (TGA). [Means for solving the problem]

[0006] The present invention provides a masterbatch composition suitable for use as a flame retardant in extruded polymer foams, comprising: (a) 20 to 40 parts by weight of a base resin comprising a styrene homopolymer or copolymer; (b) 1 to 16 parts by weight of an acid scavenger comprising an epoxy-based compound; (c) 2 to 6 parts by weight of an antioxidant comprising an alkyl phosphite or an aryl phosphite; and (d) 45 to 60 parts by weight of a flame retardant comprising a non-hexabromocyclododecane (HBCD) brominated polymer or copolymer. Includes; the amounts of (a), (b), (c), and (d) total 100 parts by weight; The masterbatch composition comprises (e) a water-soluble pH adjuster, the water-soluble pH adjuster being 0.6 to 10 parts by weight based on 100 parts of the base resin plus at least one water-soluble pH adjuster; The present invention relates to a masterbatch composition further comprising:

[0007] The present invention provides an extruded polymer foam comprising a masterbatch composition, the masterbatch composition comprising: (a) 20 to 40 parts by weight of a base resin comprising a styrene homopolymer or copolymer; (b) 1 to 16 parts by weight of an acid scavenger comprising an epoxy-based compound; (c) 2 to 6 parts by weight of an antioxidant comprising an alkyl phosphite or an aryl phosphite; and (d) 45 to 60 parts by weight of a flame retardant comprising a non-hexabromocyclododecane (HBCD) brominated polymer or copolymer. Includes; the amounts of (a), (b), (c), and (d) total 100 parts by weight; The masterbatch composition comprises (e) 0.6 to 10 parts by weight of a water-soluble pH adjuster based on 100 parts of the (a) base resin plus the (e) water-soluble pH adjuster The present invention also relates to an extruded polymer foam, further comprising:

[0008] The present invention provides a process for making a masterbatch composition suitable for use as a flame retardant in extruded polymer foams, comprising: a) providing a base resin to a mixing device operating at a temperature of 150-230°C to form a molten base resin; b) mixing the molten base resin in the mixing device; i) an acid scavenger comprising one or more epoxy-based compounds; ii) antioxidants including alkyl phosphites or aryl phosphites; iii) a water-soluble pH adjuster; and iv) Flame retardants containing non-hexabromocyclododecane (HBCD) brominated polymers or copolymers to form a molten flame retardant masterbatch composition; and c) cooling the molten flame-retardant masterbatch composition to form a solid flame-retardant masterbatch composition. The present invention further relates to a process including: [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram of one possible process for producing pellets of a masterbatch composition using a twin-screw extrusion line. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention relates to a more environmentally friendly masterbatch composition suitable for use as a flame retardant in extruded polymer foams, the masterbatch composition comprising: (a) a base resin comprising a styrene homopolymer or copolymer; (b) an acid scavenger comprising an epoxy-based compound; (c) an antioxidant comprising an alkyl phosphite or aryl phosphite; (d) a non-hexabromocyclododecane (HBCD) brominated polymer or copolymer; and (e) a flame retardant comprising a water-soluble pH adjuster.

[0011] By "masterbatch composition" it is meant that the composition can be used as an additive in resins and foams.

[0012] By "flame retardant" is meant that the ingredient has the ability to increase the limiting oxygen index (LOI) value of melt-processed articles such as foams, fibers, films, etc., thereby enabling such articles to pass standard fire tests. Air contains approximately 21% oxygen, and therefore, any material with an LOI value of 21 or less can potentially burn in air. Specifically, for purposes of this specification, an ingredient is considered a flame retardant if its presence in a composition or formulation can increase the LOI of the article to 24 or greater. A limiting oxygen index of 24 or greater allows many foam articles to pass standard fire tests, such as Underwriters Laboratory (UL) 723 and European Norm (EN) Fire Test #ISO 11925-2 Class E, as well as North American Building Code standards C578 and S701.

[0013] (a) Base resin The masterbatch composition includes a base resin primarily used as a carrier resin for compounding a flame retardant with other additives. The base resin containing a styrene homopolymer or copolymer is present in an amount of 20 to 40 parts by weight based on the total amount in the masterbatch composition. The masterbatch composition includes (a) the base resin containing a styrene homopolymer or copolymer, (b) an acid scavenger containing an epoxy compound, (c) an antioxidant containing an alkyl phosphite or aryl phosphite, and (d) a flame retardant containing a non-hexabromocyclododecane (HBCD) brominated polymer or copolymer.

[0014] For purposes of this specification, it is understood that the "base resin comprising a styrene homopolymer or copolymer" described herein can be one or more resins comprising a styrene homopolymer or copolymer, and the amount of "base resin comprising a styrene homopolymer or copolymer" is considered to be the total amount of resin comprising a styrene homopolymer or copolymer in the masterbatch composition, separate from any flame retardant polymer comprising a styrene homopolymer or copolymer. Also, for purposes of this specification regarding the amounts of components in a masterbatch, the base resin comprising a styrene homopolymer or copolymer is considered to be separate from the flame retardant comprising a non-hexabromocyclododecane (HBCD) brominated polymer or copolymer.

[0015] If the base resin content in the masterbatch composition is less than 20 parts by weight, the viscosity and melting temperature of the masterbatch can increase, especially above 230°C, which may lead to increased thermal decomposition due to shear heating. The presence of the base resin also helps disperse the components in the masterbatch; if too little base resin is present, the flame retardant may not be adequately dispersed, instead forming large domains of flame retardant in the masterbatch. This can adversely affect the ability of acid scavengers, antioxidants, and pH adjusters to effectively protect the flame retardant. Having more than 40 parts by weight of base resin in the masterbatch composition is undesirable because it unnecessarily increases the cost of producing the masterbatch. In some embodiments, the base resin, including a styrene homopolymer or copolymer, is present in the masterbatch composition in an amount of 26 to 35 parts by weight, based on the total amount of the aforementioned components (a), (b), (c), and (d).

[0016] Some preferred base resins include polystyrene homopolymer and copolymers of styrene with ethylene, propylene, acrylic acid, maleic anhydride, and / or acrylonitrile. Polystyrene homopolymer is most preferred. Mixtures of any two or more of the foregoing polymers or one or more of the foregoing polymers with another resin can also be used as the base resin.

[0017] In some embodiments, styrene / butadiene copolymer base resins are particularly preferred. Some styrene / butadiene block copolymers useful as starting polymers include those available from Dexco Polymers under the trade name VECTOR™. Styrene / butadiene random copolymers can be prepared according to the process described in AF Halasa's Polymer, Volume 46, page 4166 (2005). Styrene / butadiene graft copolymers can be prepared according to the method described in AF Halasa's Journal of Polymer Science (Polymer Chemistry Edition), Volume 14, page 497 (1976). Styrene / butadiene random and graft copolymers can also be prepared according to the method described in chapter 9 of Anionic Polymerization Principles and Practical Applications by Hsieh and Quirk, Marcel Dekker, Inc., New York, 1996. The starting polymer can also contain repeating units formed by polymerizing a monomer other than butadiene with a vinyl aromatic monomer. Such other monomers include olefins such as ethylene and propylene, acrylates or acrylic monomers such as methyl methacrylate, methyl acrylate, acrylic acid, etc. These monomers can be randomly polymerized with vinyl aromatic monomers and / or butadiene to form blocks or grafted onto the starting butadiene copolymer. The most preferred type of starting butadiene polymer is a block copolymer containing one or more polystyrene blocks and one or more polybutadiene blocks. Among these, diblock and triblock copolymers are particularly preferred.

[0018] (b) Acid scavenger The acid scavenger comprising an epoxy-based compound is present in the masterbatch composition in an amount of 1 to 16 parts by weight, based on the total amount of the masterbatch composition: (a) a base resin comprising a styrene homopolymer or copolymer; (b) an acid scavenger comprising an epoxy-based compound; (c) an antioxidant comprising an alkyl phosphite or aryl phosphite; and (d) a flame retardant comprising a non-hexabromocyclododecane (HBCD) brominated polymer or copolymer.

[0019] For purposes of this specification, it is understood that the "acid scavenger comprising an epoxy-based compound" described herein may be one or more acid scavengers comprising an epoxy-based compound, and the amount of "acid scavenger comprising an epoxy-based compound" is considered to be the total amount of acid scavengers comprising an epoxy-based compound in the masterbatch composition.

[0020] Less than 1 part by weight of acid scavenger in the masterbatch composition is believed to not provide sufficient acid scavenging performance to the masterbatch, and more than 20 parts by weight of acid scavenger in the masterbatch composition is undesirable because the higher amount does not provide significant benefit justifying the increased cost, and the higher amount may cause the masterbatch pellets to stick together. In some embodiments, the acid scavenger is present in the masterbatch composition in an amount of 4 to 10 parts by weight based on the total amount of the aforementioned components (a), (b), (c), and (d).

[0021] Additionally, the acid scavenger is present in the masterbatch composition at 3 to 11 parts by weight per 100 parts by weight of the flame retardant. In some embodiments, the acid scavenger is present in the masterbatch composition at 4 to 7 parts by weight per 100 parts by weight of the flame retardant. In some embodiments, the acid scavenger is present in the masterbatch composition at 8 to 10 parts by weight per 100 parts by weight of the flame retardant.

[0022] In some embodiments, the epoxy compound contains an average of at least one, preferably two or more, epoxide groups per molecule. The epoxy compound preferably has an equivalent weight per epoxide group of 2000 or less, preferably 1000 or less, and even more preferably 500 or less. The molecular weight of the epoxy compound is at least 1000 in some preferred embodiments. The epoxy compound may further be brominated. Various commercially available epoxy resins are suitable. These may be based on bisphenol compounds, such as various diglycidyl ethers of bisphenol A. They may be based on brominated bisphenol compounds. The epoxy compound may be an epoxy novolac resin or an epoxy cresol novolac resin. The epoxy compound may be a diglycidyl ether of polyether diol or a fully aliphatic material, such as epoxidized vegetable oil. Examples of commercially available epoxy compounds useful herein include F2200HM and F2001 (manufactured by ICL Industrial Products), DEN 439 (manufactured by The Dow Chemical Company), Araldite ECN-1273 and ECN-1280 (manufactured by Huntsman Advanced Materials Americas, Inc.), and Plaschek 775 (manufactured by Valtris Specialty Chemicals).

[0023] In some preferred embodiments, the acid scavenger comprises an epoxy cresol novolac resin. In some other preferred embodiments, the acid scavenger comprises an epoxidized oil. In some other preferred embodiments, both an epoxy cresol novolac resin and an epoxidized oil are present in the masterbatch composition as acid scavengers. In some other preferred embodiments, the acid scavenger in the composition comprises a majority of the epoxidized oil; i.e., greater than 50 wt. % of the epoxy compounds present in the masterbatch composition are in the form of an epoxidized oil.

[0024] (c) Antioxidants The masterbatch composition includes at least one antioxidant to stabilize radicals formed during the preparation of the masterbatch composition and subsequent incorporation of the masterbatch composition into a foam composition. These undesirable radicals can lead to undesirable color formation and crosslinking that can contaminate foam process equipment, requiring downtime for cleaning.

[0025] The antioxidant containing an alkyl phosphite or an aryl phosphite is present in a masterbatch composition of (a) a base resin containing a styrene homopolymer or copolymer, (b) an acid scavenger containing an epoxy compound; (c) an antioxidant containing an alkyl phosphite or an aryl phosphite; and (d) a flame retardant containing a non-hexabromocyclododecane (HBCD) brominated polymer or copolymer in an amount of 2 to 6 parts by weight, based on the total amount in the masterbatch composition.

[0026] For purposes of this specification, it is understood that the "antioxidant comprising an alkyl phosphite or an aryl phosphite" described herein can be one or more antioxidants comprising an alkyl phosphite or an aryl phosphite, and the amount of "antioxidant comprising an alkyl phosphite or an aryl phosphite" is considered the total amount of antioxidants comprising an alkyl phosphite or an aryl phosphite in the masterbatch composition.

[0027] Less than 2 parts by weight of antioxidant in the masterbatch composition is believed to not provide sufficient inhibition of undesired oxidation reactions, and more than 6 parts by weight of antioxidant in the masterbatch composition is believed to be undesirable due to added cost without any apparent benefit. In some embodiments, the antioxidant comprising an alkyl phosphite or aryl phosphite is present in the masterbatch composition in an amount of 3 to 4.5 parts by weight based on the total amount of the aforementioned components (a), (b), (c), and (d).

[0028] Suitable alkyl phosphites are described in U.S. Patent No. 9,663,649 to Kram et al. Specific examples of preferred alkyl phosphites include bis(2,4-dicumylphenyl)pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, and di(2,4-di-(t-butyl)phenyl)pentaerythritol diphosphite, which are commercially available as Doverphos™ S-9228 (Dover Chemical Corporation), Doverphos™ S-682 (Dover Chemical Corporation), and Irgafos™ 126 (Ciba Specialty Chemicals).

[0029] Suitable aryl phosphites are described in Huang et al., International Publication No. 2014 / 174704. Specific examples of some preferred aryl phosphites include substituted aryl phosphites. One such preferred specific aryl phosphite is tris(2,4-di-tert-butylphenyl)phosphite, commercially available under the name Irgafos™ 168. If desired, a mixture of both alkyl phosphites and aryl phosphites can be used together in the masterbatch.

[0030] Additionally, the antioxidant is present in the masterbatch composition at 3 to 11 parts by weight per 100 parts by weight of the flame retardant. In some embodiments, the antioxidant is present at 4 to 7 parts by weight per 100 parts by weight of the flame retardant. In some embodiments, the antioxidant is present at 8 to 10 parts by weight per 100 parts by weight of the flame retardant.

[0031] (d) Flame retardants The flame retardants used in the masterbatch compositions are non-hexabromocyclododecane (HBCD) brominated polymers and copolymers that are considered to be more environmentally responsible alternatives to HBCD, a flame retardant commonly used in polystyrene foam that has experienced government regulatory issues due to bioaccumulation concerns.

[0032] In some embodiments, preferred flame retardants for use in the masterbatch composition are thermally stable brominated copolymers, such as brominated styrene / butadiene block copolymers (Br-SBC), brominated random styrene / butadiene copolymers (Br-r-SB), or brominated styrene / butadiene graft copolymers (Br-g-SB), such as those described in U.S. Pat. No. 7,851,558 to King et al.

[0033] In some embodiments, a preferred non-HBCD brominated polymer or copolymer flame retardant has the following structure and is commercially available from DuPont Company, Inc. under the name BLUEDGE™ polymeric flame retardant (PFR), also available as Emerald Innovation™ 3000 and FR122P: [ka]

[0034] Some other suitable non-HBCD brominated polymer or copolymer flame retardants are disclosed in the U.S. Environmental Protection Agency's "Flame Retardant Alternatives For Hexabromocyclododecane (HBCD)—Final Report" (June 2014). One class of non-HBCD brominated flame retardants mentioned in the report were TBBPA-bis brominated ether derivatives, such as those having the chemical name (1,1'-(1-methylethylidene)bis[3,5-dibromo-4-(2,3-dibromo-2-methylpropoxy)]benzene), commercially available under the names PYROGUARD SR-130 and SR-130. Another class of non-HBCD brominated flame retardants mentioned in the report was TBBPA bis(2,3-dibromopropyl) ether, which has the chemical name (1,1'-(1-methylethylidene)bis[3,5-dibromo-4-(2,3-dibromopropoxy)]benzene), commercially available under the names PYROGUARD SR 720 and SR 720. While each of the non-HBCD brominated flame retardants can be used in the masterbatch by itself, in some instances it may be desirable to have a mixture of these non-HBCD brominated flame retardants in the masterbatch.

[0035] In some embodiments, the flame retardant used in the masterbatch composition comprises a brominated styrene / butadiene block copolymer in which less than 1% of the carbon-bromine bonds are allylic or tertiary. Furthermore, in preferred embodiments, the amount of flame retardant used in the masterbatch composition should be sufficient to provide 0.35-5 wt. % bromine in the extruded polymer foam composition to which the masterbatch is added. In some embodiments, the amount of flame retardant used in the masterbatch composition should be sufficient to provide 1.0-2.5 wt. % bromine in the extruded polymer foam composition.

[0036] Furthermore, while the total amount of masterbatch added to the foam composition can vary widely depending on the type of foam, the desired foam application, and the inclusion of other additives, it is often desirable for the masterbatch to be present in the final foam in an amount ranging from about 0.5 to about 7.6 wt.%, based on the combined weight of the foam and masterbatch. In some embodiments, the masterbatch is present in the final foam in an amount ranging from about 0.6 to 4 wt.%, based on the combined weight of the foam and masterbatch; while in other embodiments, the masterbatch is present in the final foam in an amount ranging from about 3 to 7.6 wt.%, based on the combined weight of the foam and masterbatch.

[0037] The non-HBCD brominated polymer or copolymer flame retardant is present in the masterbatch composition in an amount of 45 to 60 parts by weight, based on the total amount in the masterbatch composition of: (a) a base resin including a styrene homopolymer or copolymer; (b) an acid scavenger including an epoxy-based compound; (c) an antioxidant including an alkyl phosphite or aryl phosphite; and (d) a flame retardant including a non-hexabromocyclododecane (HBCD) brominated polymer or copolymer.

[0038] For purposes of this specification, it is understood that the "flame retardant comprising a non-hexabromocyclododecane (HBCD) brominated polymer or copolymer" described herein can be one or more flame retardants comprising a non-hexabromocyclododecane (HBCD) brominated polymer or copolymer, and the amount of "flame retardant comprising a non-hexabromocyclododecane (HBCD) brominated polymer or copolymer" is considered to be the total amount of flame retardant comprising a non-hexabromocyclododecane (HBCD) brominated polymer or copolymer in the masterbatch composition. Also, for purposes of this specification regarding the amounts of components in a masterbatch, the flame retardant comprising a non-hexabromocyclododecane (HBCD) brominated polymer or copolymer is considered to be separate from the base resin comprising a styrene homopolymer or copolymer.

[0039] Approximately 45 parts by weight of a non-HBCD brominated polymer or copolymer flame retardant in the masterbatch composition is believed to be the minimum practical amount for a desirable masterbatch composition suitable for use in many applications. Below this amount, some flame retardancy is still obtained, but not at the level required by many FR standards. This means that additional flame retardants must be added separately to the final foam composition to meet these standards, essentially defeating the purpose of having a single flame-retardant masterbatch composition. Furthermore, more than 60 parts by weight of a non-HBCD brominated polymer or copolymer flame retardant in the masterbatch composition is undesirable. Such masterbatches with high concentrations of flame retardant are not only susceptible to thermal decomposition due to shear heating, but also have higher viscosities, which make them more difficult to disperse in foam formulations. 45-60 parts by weight of a non-HBCD brominated polymer or copolymer flame retardant in the masterbatch provides a bromine loading of approximately 29-40% in the masterbatch. In some embodiments, the non-HBCD brominated polymer or copolymer flame retardant is present in the masterbatch composition in an amount of 50 to 55 parts by weight based on the total amount of components (a), (b), (c), and (d) in said masterbatch.

[0040] (e) Water-soluble pH adjuster The masterbatch composition further comprises 0.6 to 10 parts by weight of a water-soluble pH adjuster based on 100 parts of the (a) base resin and the (e) water-soluble pH adjuster. In some embodiments, the masterbatch has a minimum of 1 part by weight of a water-soluble pH adjuster and a maximum of 10 parts by weight of a water-soluble pH adjuster based on 100 parts of the (a) base resin and the (e) water-soluble pH adjuster. In some other embodiments, the masterbatch has a minimum of 1.5 parts by weight of a water-soluble pH adjuster and a maximum of 10 parts by weight of a water-soluble pH adjuster based on 100 parts of the (a) base resin and the (e) water-soluble pH adjuster.

[0041] For purposes of this specification, it is understood that the "water-soluble pH adjuster" described herein may be one or more water-soluble pH adjusters, and the amount of "water-soluble pH adjuster" is considered to be the total amount of water-soluble pH adjuster in the masterbatch composition.

[0042] Less than 0.6 parts by weight of water-soluble pH adjuster is believed to not provide sufficient stabilization performance to the masterbatch, and more than 10 parts by weight of water-soluble pH adjuster is believed to be undesirable because larger amounts may accumulate on the die and affect foam quality. In some embodiments, the masterbatch composition comprises 5 to 10 parts by weight of water-soluble pH adjuster, and in some embodiments, 6 to 10 parts by weight of water-soluble pH adjuster, based on 100 parts of (a) base resin + (e) water-soluble pH adjuster. In some other embodiments, the masterbatch composition again comprises 1.5 to 5 parts by weight of water-soluble pH adjuster, based on 100 parts of (a) base resin + (e) water-soluble pH adjuster.

[0043] By "water soluble" it is meant that the pH adjuster has a solubility in water at room temperature (20°C, 68°F) of at least 20 grams per liter. Preferably, the water soluble pH adjuster has a solubility in water at room temperature (20°C, 68°F) of at least 90 grams per liter. This level of solubility ensures that the pH adjuster is fully available upon contact with acidic species in the aqueous phase during the foam production process.

[0044] Furthermore, in some embodiments, preferred water-soluble pH adjusters are those that do not form undesirable by-products in the masterbatch or foam after reacting with free hydrogen bromide. In some most preferred embodiments, the water-soluble pH adjuster is a compound that reacts with hydrogen bromide to essentially form only a salt as a by-product. For example, sodium carbonate reacts with HBr to form sodium bromide and sodium bicarbonate. Similarly, sodium bicarbonate reacts with HBr to form sodium bromide, carbon dioxide, and water. In some other embodiments, suitable water-soluble pH adjusters are compounds that react with hydrogen bromide to essentially form only a salt or weak acid as a by-product. For example, sodium borate, such as sodium tetraborate decahydrate, forms sodium bromide and a very weak boric acid.

[0045] In some embodiments, the water-soluble pH adjuster is sodium carbonate, sodium bicarbonate, or a borate, such as sodium tetraborate decahydrate. In some preferred embodiments, the water-soluble pH adjuster is sodium carbonate, commonly known as soda ash. The use of soda ash has several unexpected advantages. First, soda ash is a weak base, but has been found to have sufficient alkalinity and reaction rate to effectively neutralize the strong acid HBr produced by the decomposition of the carbon-bromide bond from the backbone of the brominated flame retardant.

[0046] Second, soda ash can be well dispersed in polymers and does not significantly adversely affect the foaming process in which the masterbatch composition is used. No process problems such as die buildup or surface defects on the resulting foams were observed.

[0047] Third, soda ash is a mildly volatile additive in the process because it is highly soluble in water and ultimately produces the by-products H2O and CO2 common to many foaming processes as blowing agents.

[0048] Finally, it has been unexpectedly discovered that the addition of soda ash can reduce the amount of costly organic epoxide acid scavenger required in the composition, as evidenced by similar TGA decomposition onset times for masterbatches and foams when a portion of the acid scavenger is replaced with a pH adjuster.

[0049] While epoxy-based acid scavengers are organic and can manage acidic species in the organic phase, the addition of a water-soluble pH adjuster can help maintain the pH in the aqueous phase, where acidic species such as HBr have high mobility and can rapidly drive the dehydrohalogenation reaction kinetics. In particular, the use of soda ash significantly impacts the induction time of side chemical kinetics, which can lead to undesirable viscosity increases via crosslinking in formulations containing styrene-acrylonitrile (SAN) copolymers.

[0050] Furthermore, it is unexpected that suitable foams can be produced using a flame-retardant masterbatch containing 0.6 to 10 parts by weight of a water-soluble pH adjuster based on 100 parts of (a) base resin and (e) water-soluble pH adjuster, especially since the stabilizer is an inorganic material. Conventional wisdom holds that even when used in small amounts, inorganic materials can form deposits on treated surfaces, slough off, and cause defects in the masterbatch or foam. Furthermore, these undesirable deposits have a long thermal history that can reduce the thermal stability of the masterbatch and foam. Therefore, it is not expected that any of the appropriate amounts of water-soluble pH adjusters discussed herein would be able to produce completely suitable foams.

[0051] Manufacturing process of masterbatch composition The present invention provides a process for making a masterbatch composition suitable for use as a flame retardant in extruded polymer foams, comprising: a) providing a base resin to a mixing device operating at a temperature of 150-230°C to form a molten base resin; b) mixing the molten base resin in the mixing device; i) an acid scavenger comprising one or more epoxy-based compounds; ii) antioxidants including alkyl phosphites or aryl phosphites; iii) a water-soluble pH adjuster; and iv) Flame retardants containing non-hexabromocyclododecane (HBCD) brominated polymers or copolymers to form a molten flame retardant masterbatch composition; and c) cooling the molten flame-retardant masterbatch composition to form a solid flame-retardant masterbatch composition. The present invention further relates to a process including:

[0052] In some embodiments, a process for making a masterbatch composition suitable for use as a flame retardant in extruded polymer foams comprises: d) pelletizing the solid flame retardant masterbatch composition to form pellets. It may further include:

[0053] The process for producing a masterbatch composition suitable for use as a flame retardant in extruded polymer foam involves combining and mixing together a number of ingredients, including a base resin, a flame retardant, an antioxidant, an acid scavenger, and a water-soluble pH adjuster, at a temperature suitable to produce a molten mixture of the masterbatch, and then cooling the molten composition to form a solid, which is then optionally formed into pellets.

[0054] Mixing can be achieved in any device capable of providing (or maintaining) the components at a suitable elevated temperature so that the base resin and organic additives melt and all components are properly and uniformly dispersed in the molten phase. It is generally convenient to melt a certain amount of base resin as a carrier and then add the other components, either alone or in admixture. Therefore, extruders, particularly twin-screw extruders and variants using screw-type or other mixing elements, such as a Farrel continuous mixer, are typically preferred, as they allow for continuous production of masterbatches. However, mixing can be performed in batch mode using any type of mixer capable of operating at high temperatures.

[0055] In a preferred process, the base resin described herein above is provided in pellet or powder form to a mixing device, such as a twin-screw extruder operating at a temperature of about 150-230°C, which forms a molten base resin. The base resin and any of the other ingredients in pellet or powder form can be metered into the extruder using gravimetric feeders or hoppers designed to feed the extruder or other homogenous equipment, such as a feeder extruder. Components in liquid form can be fed into the extruder using metering pumps or any of a variety of pumping and metering devices.

[0056] The molten base resin in the mixing device is then contacted with at least one acid scavenger comprising one or more epoxy-based compounds, at least one antioxidant, and at least one water-soluble pH adjuster.

[0057] In some preferred processes, the acid scavenger is an epoxidized oil or an epoxy cresol novolac resin. In some particularly preferred processes, the molten base resin is contacted with both the epoxidized oil and the epoxy cresol novolac resin. This can be accomplished sequentially by separate additions, since the oil is a liquid and the resin can be in pellet or powder form. In some embodiments where epoxidized oil is used, it is preferred that it be the majority of the acid scavenger used in the process, as the oil provides some additional lubricating qualities to the extrusion process.

[0058] Antioxidants and water-soluble pH adjusters are generally added to the composition in small amounts, while flame retardants generally form the majority of the components in the masterbatch. Each of these components can be added separately to the mixing device, but it may be convenient to first mix the solid (powder and / or pellet) components together and then add this mixture to the mixing device.

[0059] The antioxidant includes an alkyl phosphite or aryl phosphite as previously described herein. The water-soluble pH adjuster is as previously described herein, preferably soda ash, and is added in an amount of 0.6 to 10 parts by weight of water-soluble pH adjuster based on 100 parts of base resin plus pH adjuster.

[0060] After proper mixing to form a uniform molten masterbatch composition, the molten flame-retardant masterbatch composition is cooled to form a solid masterbatch composition. When the mixer is an extruder, the molten masterbatch composition is typically extruded through a die to form strands of molten material, which are then cooled to form solid strands. The solid masterbatch can then optionally be formed into masterbatch pellets. One suitable method for cooling the molten flame-retardant masterbatch composition is by extruding the composition through a die, followed by quenching the strands using one or more water baths; the quenched strands can then be directed through a pelletizer, such as an underwater pelletizer, if masterbatch pellets are desired. Preferably, the pellets are sized so that there are 25 to 40 pellets per gram.

[0061] One possible manufacturing process for a flame-retardant masterbatch composition is shown in Figure 1. A twin-screw extruder 10, maintained at an elevated temperature, is fed with polystyrene pellets via Feeder 1. Because a small amount of solid epoxy cresol novolac resin is typically used, a pellet or powder mixture of polystyrene and epoxy cresol novolac resin can be formed and introduced into the extruder via Feeder 2. In this process, liquid epoxidized oil is then metered into the extruder via Injector 3. Finally, in this process, a mixture of flame retardant, antioxidant, and water-soluble pH adjuster is added via side feeder 4.

[0062] The twin-screw extruder extrudes the molten flame retardant masterbatch composition through a die into strands that are quenched in a water bath 20; the quenched strands are then directed to a pelletizer 30 to form masterbatch pellets 40.

[0063] As shown in Figure 1, in one process for making a masterbatch composition, preferably, at least one of at least one acid scavenger, at least one antioxidant, or water-soluble pH adjuster contacts the molten base resin in the mixing device before the flame retardant contacts the base resin. In a particularly preferred process for making a masterbatch composition, at least one acid scavenger contacts the molten base resin in the mixing device before the flame retardant contacts the base resin. This provides the base resin with a pre-loaded protective component that helps prevent thermal decomposition of the flame retardant during its entire time at elevated temperatures.

[0064] Further, as described above, preferably, the process for making the masterbatch composition comprises: (a) providing 20 to 40 parts by weight of at least one base resin comprising a styrene homopolymer or copolymer to a mixing device operating at a temperature of 150 to 230°C to form a molten base resin, and then contacting the base resin with: (b) 1 to 16 parts by weight of at least one acid scavenger comprising an epoxy-based compound; (c) 2 to 6 parts by weight of at least one antioxidant comprising an alkyl phosphite or aryl phosphite; and (d) a flame retardant comprising a non-hexabromocyclododecane (HBCD) brominated polymer or copolymer; the amounts of (a), (b), (c), and (d) totaling 100 parts by weight; and the masterbatch composition further comprises: (e) 0.6 to 10 parts by weight of a water-soluble pH adjuster, based on 100 parts of the (a) at least one base resin + (e) water-soluble pH adjuster.

[0065] Extruded Foam The present invention further relates to an extruded polymer foam comprising a masterbatch composition suitable for use as a flame retardant in the extruded polymer foam, the masterbatch comprising: (a) a base resin comprising a styrene homopolymer or copolymer; (b) an acid scavenger comprising an epoxy-based compound; (c) an antioxidant comprising an alkyl phosphite or an aryl phosphite; (d) a non-hexabromocyclododecane (HBCD) brominated polymer or copolymer; and (e) a water-soluble pH adjuster.

[0066] Extruded foams can be produced using many different processes, such as those disclosed in U.S. Patent No. 9,517,579 to Kram et al. The flame-retardant masterbatch composition is particularly useful in the production of foam boards, such as those produced in large quantities from styrenic polymers in a melt extrusion process. Such extrusion foaming processes are carried out by forming a pressurized melt containing the polymer to be foamed, collectively referred to herein as the bulk polymer, and the masterbatch composition blowing agent suitable for use as a flame retardant, as described herein, and other additives such as may be useful. However, one advantage of using the present masterbatch is that preferably only the bulk polymer, masterbatch, and blowing agent are required.

[0067] The bulk polymer and masterbatch are conveniently supplied to the foam processing equipment in the form of pellets or other small particulates that are melted in the foam processing equipment. The masterbatch can be premixed or added to the foam processing equipment simultaneously with the bulk polymer, in which case the bulk polymer and masterbatch are melted simultaneously in the foam processing equipment. Alternatively, the masterbatch can be added to the foam processing equipment after the bulk polymer, in which case the bulk polymer is partially or completely melted. The foam processing equipment must be of adequate capacity, and the processing speed must be adequate to uniformly and completely melt and disperse the flame retardant masterbatch in the bulk polymer.

[0068] It is generally preferred to introduce the blowing agent as a separate stream after the polymeric material has been melted. Blowing agents in extrusion foaming processes can be of the exothermic (chemical) or endothermic (physical) type. Physical blowing agents such as carbon dioxide, various hydrocarbons, hydrofluorocarbons, water, alcohols, ethers, and hydrochlorofluorocarbons are particularly suitable.

[0069] The flame retardant masterbatches of the present invention having a water-soluble pH adjuster are particularly useful when water is used as at least one of the blowing agents, although the water-soluble pH adjuster is also effective when water is not the blowing agent, since many ingredients are not completely free of water and most processing equipment is not inerted to prevent water absorption by the materials during the extrusion foaming process.

[0070] In one embodiment, the blowing agent is a mixture, which may include carbon dioxide, ethanol, and water. In another embodiment, the blowing agent may include carbon dioxide, ethanol, a C4-C5 hydrocarbon, and water. The C4-C5 hydrocarbon is preferably isobutane. Preferably, the total amount of blowing agent is 40 kg / m of the extruded foam. 3 Less than or equal to 36 kg / m 3 or less, and even more preferably 35 kg / m 3The blowing agent is used in an amount sufficient to provide the following foam densities: These densities are believed to be best achieved when the total amount of blowing agent is within the range of about 1.1 to about 1.8 moles of blowing agent per kilogram of bulk polymer. In some instances, the preferred total amount of blowing agent is 1.1 to about 1.7 moles per kilogram of bulk polymer. An even more preferred amount is 1.15 to 1.65 moles per kilogram of bulk polymer. Individually, carbon dioxide is preferably used in an amount of about 0.5 to about 1.2 moles per kilogram of bulk polymer, more preferably 0.65 to about 0.9 moles per kilogram of bulk polymer. Ethanol is preferably used in an amount of 0.15 to 0.5 moles per kilogram of bulk polymer, more preferably 0.25 to 0.45 moles per kilogram of bulk polymer. Water is preferably used in an amount of about 0.1 to about 0.4 moles per kilogram of bulk polymer, more preferably 0.1 to 0.3 moles per kilogram of bulk polymer. The C4 to C5 hydrocarbons are preferably present in an amount of up to 0.35 moles per kilogram of bulk polymer, more preferably from 0.1 to 0.3 moles per kilogram of bulk polymer.

[0071] In one embodiment, the blowing agent comprises a combination of 0.65-0.9 moles of carbon dioxide, 0.25-0.45 moles of ethanol, and 0.1-0.3 moles of water per kilogram of bulk polymer, for a total amount of blowing agent of 1.1-1.65 moles per kilogram of bulk polymer. In another embodiment, the blowing agent comprises a combination of 0.65-0.9 moles of carbon dioxide, 0.25-0.45 moles of ethanol, 0.1-0.3 moles of isobutene, and 0.1-0.3 moles of water per kilogram of bulk polymer, for a total amount of blowing agent of 1.15-1.65 moles per kilogram of bulk polymer.

[0072] The bulk polymer, masterbatch and other optional additives are mixed, the polymer is melted and further mixed with the blowing agent and the resulting gel is forced through an orifice into a low pressure area where the blowing agent expands and the polymer solidifies to form the extruded foam.

[0073] The foam thus produced preferably has a viscosity of 80 kg / m 3 up to 64 kg / m 3 up to, and even more preferably, 48 kg / m 3 The foams used as thermal insulation preferably have a density of 24 to 48 kg / m 3 The billet foam is preferably in the form of board stock having a density of 24 to 64 kg / m 3 , more preferably 28 to 48 kg / m 3 The foam preferably has an average cell size ranging from 0.1 mm to 4.0 mm, especially 0.1 mm to 0.8 mm, as determined according to ASTM D3576. The foam may be predominantly closed-cell, i.e., contain 30% or less, preferably 10% or less, and even more preferably 5% or less, open cells, as determined according to ASTM D6226-05. The present invention also allows for the production of more open-cell foams.

[0074] Boardstock foams made according to the present invention are useful as architectural foam insulation, as part of a roof or wall assembly. Other foams made according to the present invention can be used as decorative billets, pipe insulation, and in molded concrete foundation applications.

[0075] Test Method Decomposition onset time of brominated polymer concentrate by thermogravimetric analysis (TGA). TGA is a method of thermal analysis that measures changes in the physical and chemical properties of a material as a function of increasing temperature (at a constant heating rate) or as a function of time (at a constant temperature and / or constant mass loss). TGA is typically used to determine selected properties of a material that exhibit either mass loss or gain due to decomposition, oxidation, or loss of volatiles (such as moisture). After loading the sample, the flask is isothermally held at 25°C for 5 minutes under nitrogen, ramped at 25°C / min to 235°C. The flask is isothermally maintained at 235°C for 60 minutes, then cooled to 30°C. The TGA onset time is defined as the time at which significant decomposition begins (inflection point).

[0076] Yellowness Index (YI) Measurement. Yellowness Index (YI) is measured in accordance with ASTM E315-15. Samples are measured by spectrophotometer or tristimulus (filter) colorimeter. X, Y, and Z values ​​are determined for each measurement; if multiple measurements are made on a single sample and set of conditions, average values ​​for X, Y, and Z are provided. For pellets, YI must be less than 75; for plaques, YI must be less than 40.

[0077] Glass transition temperature (Tg) onset. Samples with a mass of 5-10 mg were cut from the pellet, weighed, and sealed in aluminum DSC pans for analysis. Samples were scanned using a TA Instruments Q2000 DSC (differential scanning calorimeter) with an autosampler and a nitrogen purge rate of 50 ml / min. The heating rate was 10 °C / min, and a temperature profile between 20 °C, 200 °C, and back to 20 °C was applied twice to each sample. Scans were analyzed using Universal Analysis V4.7A software. The glass transition temperature (Tg) onset was determined as the inflection point of the baseline step transition, reported in degrees Celsius.

[0078] Reference example This example illustrates some of the benefits of sodium carbonate and sodium borate as pH adjusters as additives in flame-retardant masterbatches suitable for use in foams. Various amounts of undesirable hydrogen bromide (HBr) are shown in Table 1, along with the amounts of sodium carbonate (Na2CO3), sodium bicarbonate (NaHCO3), and tetrasodium pyrophosphate (TSPP) needed to mitigate the HBr. As shown, TSPP is a less desirable adjuster because significantly more mass is required to handle the HBr than sodium carbonate (Na2CO3) or sodium bicarbonate (NaHCO3).

[0079] [Table 1]

[0080] Furthermore, as shown in Table 2, sodium carbonate and sodium borate are much more desirable modifiers in that the by-products of their reaction with HBr are less threatening than those of their reaction with TSPP. This can be seen by the pKa values ​​shown below for each, which indicate that sodium carbonate is preferred. Furthermore, although both sodium tetraborate decahydrates have similar pKa values, TSPP is less desirable because the counter acid formed upon reaction of sodium with bromide becomes successively more aggressive as each sodium ion is removed from the molecule, resulting in undesirable pyrophosphate. Sodium borate is more preferred, even though it has a lower solubility, because it forms a very mildly acidic species in comparison.

[0081] [Table 2] [Example]

[0082] Example 1 The following components were used to prepare the masterbatch composition:

[0083] The base resin is PolyOne 1.04g / cm 3 The flame retardant was a polystyrene resin in pellet form having a density of 1.9 g / cm from DuPont Co. 3 The additive was BLUEDGE™ polymeric flame retardant FR63 in powder form having a density of 1000 ppm. The acid scavengers were cresol novolac epoxy resin CNE 220 in pellet form from Chang Chun Chemical Corporation and Plas-Chek 775 epoxidized soybean oil (ESO) in liquid form from Valtris Specialty Chemicals. The antioxidants were Irgafos 168 in powder form from BASF and soda ash in powder form from Univar.

[0084] The masterbatch compositions were prepared in a 25 mm twin-screw extrusion system with a single-sided feeder as shown in Figure 1. Specifically, the extruder had nine barrels, a screw diameter of 25 mm, and a screw length-to-diameter ratio (L / D) of 36 / 1. The extruder temperature was set to 180°C, and the die temperature was set to 200°C.

[0085] A LiW brand weight-loss pellet feeder was used to feed pellets of low molecular weight polystyrene-based resin into the main feed throat, followed by a second LiW brand weight-loss pellet feeder feeding a mixture of the same low molecular weight polystyrene-based resin pellets and cresol novolac epoxy pellets. Preheated epoxidized soybean oil (ESO) was then fed and injected into the extruder using two 1000D Teledyne ISCO syringe pumps. Flame retardant, soda ash, and antioxidant were premixed and then fed into a side feeder, where the powder was slowly introduced into the extruder until the feed rate reached the target value. The blended polymer melt was then passed through a strand die and quenched in a water bath. The polymer strands were dried using an air blade and then pelletized using a pelletizer, producing pellets of the masterbatch composition.

[0086] The total feed rate was 160 g / min, and the screw speed was maintained at 170 rpm for all articles; other processing conditions are summarized in Table 3. For articles 5, 10, and 12, there were ESO leakage issues that prevented the formation of good masterbatches for testing. The masterbatch compositions made and the data obtained from testing those compositions, including the key properties of TGA onset time and yellowness index, are shown in Table 4. The data demonstrate that the addition of inexpensive soda ash can reduce the amount of much more expensive epoxy compound while still producing masterbatches with improved or equivalent properties.

[0087] [Table 3]

[0088] [Table 4]

[0089] Example 2 Example 1 is repeated except that one-quarter of the amount of BLUEDGE™ flame retardant is replaced by an equal weight of PYROGUARD SR 720 flame retardant. The results obtained are similar to those in Table 4.

[0090] Example 3 The polystyrene copolymer was fed into an extruder at a temperature of approximately 200°C and combined with the previously prepared masterbatch to form a molten polystyrene copolymer / masterbatch mixture to produce the foam. A masterbatch was prepared similarly to Example 1 by combining a polystyrene resin base resin, a solid acid scavenger, a liquid acid scavenger, an antioxidant, and 1.5 wt% soda ash with an equal amount of BLUEDGE™ polymeric flame retardant FR63 powder (53.8 wt%). The amount of masterbatch used in the polystyrene copolymer / masterbatch mixture was sufficient to achieve a bromine loading in the final foam of 0.35 wt%. Very small amounts of additives (e.g., talc, screw lubricant additives) were also added to the extruder to aid processing.

[0091] Extruded foams were then produced from the molten polystyrene copolymer / masterbatch mixture to confirm that the composition was suitable for producing foams that met the flame retardancy and other requirements of North American Building Code standards C578 and S701, including Underwriters Laboratory (UL) 723. To confirm foam performance, the molten polystyrene copolymer / masterbatch mixture was combined with various mixtures of blowing agents (hydrofluorocarbons, CO2, and water) to form a series of foamable mixtures. Each foamable mixture was cooled and extruded through a slit die to atmospheric pressure to form a series of foam boards. The resulting foam boards had good skin quality, were free of blowholes, and had foam densities ranging from 1.5 to 2.53 pounds per cubic foot. The thickness of the foam boards varied between 1 and 2.12 inches, as shown in Table 5. Furthermore, all foams had a nominal bromine content of 0.35% by weight and an LOI greater than 24.

[0092] Table 6 further summarizes foam properties related to codes and standards, including vertical cell size (VCS), vertical compressive strength (Vc), extrusion compressive strength (Ec), horizontal compressive strength (Hc), and Vc divided by the sum of all three (Vc / Vc+Ec+Hc), indicating the balance of cell orientation. The foams further had an open cell content of less than 5% and a measured thermal insulation performance greater than R5 per inch.

[0093] Thus, the resulting foam fully met the flame retardancy and other requirements of North American building code standards C578 and S701, including Underwriters Laboratory (UL) 723.

[0094] [Table 5]

[0095] [Table 6]

Claims

1. 1. A masterbatch composition suitable for use as a flame retardant in extruded polymer foams, comprising: (a) 20 to 40 parts by weight of a base resin comprising a styrene homopolymer or copolymer; (b) 1 to 16 parts by weight of an acid scavenger comprising an epoxy-based compound; (c) 2 to 6 parts by weight of an antioxidant comprising an alkyl phosphite or an aryl phosphite; and (d) 45 to 60 parts by weight of a flame retardant comprising a non-hexabromocyclododecane (HBCD) brominated polymer or copolymer. Including; the amounts of (a), (b), (c), and (d) total 100 parts by weight; The masterbatch composition comprises: (e) a water-soluble pH adjuster, the water-soluble pH adjuster being in an amount of 0.6 to 10 parts by weight based on 100 parts of base resin plus the at least one water-soluble pH adjuster; The masterbatch composition further comprising:

2. 10. The masterbatch composition of claim 1, wherein the base resin contains 5 to 10 parts by weight of a water-soluble pH adjuster based on 100 parts of (a) base resin plus (e) water-soluble pH adjuster.

3. 3. The masterbatch composition according to claim 1, wherein the alkyl phosphite is bis(2,4-dicumylphenyl)pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, or di(2,4-di-(t-butyl)phenyl)pentaerythritol diphosphite.

4. 3. The masterbatch composition according to claim 1, wherein the aryl phosphite is tris(2,4-di-tert-butylphenyl)phosphite.

5. The masterbatch composition according to any one of claims 1 to 4, wherein the acid scavenger comprises a brominated epoxy compound.

6. The masterbatch composition according to any one of claims 1 to 5, wherein the acid scavenger comprises an epoxy cresol novolac resin.

7. The masterbatch composition of any one of claims 1 to 6, wherein the acid scavenger comprises an epoxidized oil.

8. 8. The masterbatch composition of claim 7, wherein a majority by weight of the acid scavenger is epoxidized oil.

9. 1. An extruded polymer foam comprising a masterbatch composition, the masterbatch composition comprising: (a) 20 to 40 parts by weight of a base resin comprising a styrene homopolymer or copolymer; (b) 1 to 16 parts by weight of an acid scavenger comprising an epoxy-based compound; (c) 2 to 6 parts by weight of an antioxidant comprising an alkyl phosphite or an aryl phosphite; and (d) 45 to 60 parts by weight of a flame retardant comprising a non-hexabromocyclododecane (HBCD) brominated polymer or copolymer. Including; the amounts of (a), (b), (c), and (d) total 100 parts by weight; The masterbatch composition comprises: (e) 0.6 to 10 parts by weight of a water-soluble pH adjuster based on 100 parts of the (a) base resin plus the (e) water-soluble pH adjuster 10. The extruded polymer foam of claim 1, further comprising:

10. 10. The extruded polymer foam of claim 9, wherein (e) contains 5 to 10 parts by weight of a water-soluble pH adjuster, based on 100 parts of (a) base resin plus (e) water-soluble pH adjuster.

11. 11. The extruded polymer foam of claim 9 or 10, wherein the alkyl phosphite is bis(2,4-dicumylphenyl)pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, or di(2,4-di-(t-butyl)phenyl)pentaerythritol diphosphite.

12. The extruded polymer foam of any one of claims 9 to 11, wherein the aryl phosphite is tris(2,4-di-tert-butylphenyl) phosphite.

13. The extruded polymer foam of any one of claims 9 to 12, wherein the acid scavenger comprises a brominated epoxy compound.

14. The extruded polymer foam of any one of claims 9 to 13, wherein the acid scavenger comprises an epoxy cresol novolac resin.

15. The extruded polymer foam of any one of claims 9 to 14, wherein the acid scavenger comprises an epoxidized oil.

16. 16. The extruded polymer foam of claim 15, wherein a majority by weight of the acid scavenger is epoxidized oil.

17. 1. A process for making a masterbatch composition suitable for use as a flame retardant in extruded polymer foams, comprising: a) providing a base resin to a mixing device operating at a temperature of 150-230°C to form a molten base resin; b) mixing the molten base resin in the mixing device; i) an acid scavenger containing an epoxy compound; ii) an antioxidant comprising an alkyl phosphite or an aryl phosphite; iii) a water-soluble pH adjuster; and iv) Flame retardants comprising non-hexabromocyclododecane (HBCD) polymers or copolymers to form a molten flame retardant masterbatch composition; and c) cooling the molten flame-retardant masterbatch composition to form a solid flame-retardant masterbatch composition. A process involving:

18. d) pelletizing the solid flame retardant masterbatch composition to form pellets.

20. A process for making the masterbatch composition of claim 17, further comprising:

19. 19. The process for producing a masterbatch composition according to claim 17 or 18, wherein in step b), the acid scavenger contacting the molten base resin is an epoxidized oil, an epoxy cresol novolac resin, or a brominated epoxy compound.

20. 20. The process for making a masterbatch composition according to claim 19, wherein in step b), the molten base resin is contacted sequentially with both the epoxidized oil and the epoxy cresol novolac resin by separate addition.

21. 21. The process for making a masterbatch composition according to any one of claims 17 to 20, wherein at least one of the acid scavenger, the antioxidant, or the water-soluble pH adjuster contacts the molten base resin in the mixing device before the flame retardant contacts the base resin.

22. 22. The process for making a masterbatch composition of claim 21, wherein the acid scavenger contacts the molten base resin in the mixing device before the flame retardant contacts the base resin.

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