NL8000835A - FLAME RETARDANT, THERMOPLASTIC MATERIALS. - Google Patents

Description

S 2348-1008 Le / nb P & C

- *

Flame retardant, thermoplastic materials.

The invention relates to new flame-retardant thermoplastic materials. More particularly, the invention relates to materials containing high molecular weight polyesters in combination with flame retardant amounts of decabromodiphenyl ether, which materials have improved "bloom" resistance.

The use of high molecular weight polyesters in thermoplastic molding materials is known. These polyesters provide materials of excellent formability and articles formed therefrom with a smooth and glossy surface appearance, as well as high strength, rigidity, thermal resistance and other desirable properties.

A major shortcoming of these polyesters when used in molding materials is their normally highly flammable nature. The flammability of polyesters has been reduced by the use of additives containing halogen, phosphorus or nitrogen, and such compositions have been described in several patents and other publications. Flame-retardant, thermoplastic, polyester-containing materials are desired for many applications, e.g. in house construction, automobile and aircraft manufacturing, in packaging material, for electrical appliances, etc.

Particularly with regard to polyesters of the group of poly (alkylene dicarboxylates) and related copolyesters, it has been found difficult to render these materials adequately flame retardant without compromising their inherent superior toughness properties. In particular, the use of conventional flame retardant additives in conventional amounts detracts from toughness properties such as bending resistance and warping resistance, particularly in embodiments containing glass filler.

A very suitable group of flame retardants are polybrominated diphenyl ether compounds, in particular decabromodiphenyl ether.

These flame retardants are described in U.S. Pat. Nos. 3,624,024, 3,751,396, 3,873,491, 3,971,752, 4,010,219, and 4,070,332. Although it is stated in the literature (eg, U.S. Pat. No. 4,010,219) that diphenyl ethers having 2-10 bromine atoms are suitable, the analogous decabromodiphenyl ether is the commercially most important flame retardant for poly (1,4-butylene terephthalate) resins. Unfortunately, this compound has the undesirable property of migrating to the surface of articles formed from materials containing this compound. This property, known as "blooming" ("blooming" 8000835-2 - or "plate-out") is not only visually unacceptable, but also causes deterioration of the electrical properties at the surface of parts formed from materials in which decabromodiphenyl ether is the flame retardant.

It has now been found that upon addition of a minor effective amount of an olefin polymer and / or an olefin copolymer, eg, polyethylene, to flame retardant polyester containing materials using decabromodiphenyl ether, materials are obtained which have a surprisingly reduced tendency when exposed to high temperatures. to "flip out".

Furthermore, these materials are provided without compromising the other desirable properties (such as toughness) of the known polyester resin-containing molding materials.

For example, the addition of a polyolefin resin to mixtures of decabromodiphenyl ether and polyester gives materials that meet the stringent requirements of Underwriter's Laboratory for self-extinguishing materials in terms of flame retardancy, but which also do not "bloom" or "plate" out ") on the surface of molded parts when exposed to aging in an oven at 100 ° C, 140 ° C and 170 ° C for 1 hour, 24 hours and 168 hours. In contrast, aging of decabromodiphenyl ether and mixtures Polyester without polyolefin in an oven under the same conditions formed a powdery "rash" on the surface, adversely affecting electrical properties.

The advantages of the invention are apparent from the detailed description below.

The invention provides improved flame-retardant thermoplastic materials that do not exhibit "blowout", which include: (a) a normally high molecular weight combustible polyester; (b) a flame retardant amount of decabromodiphenyl ether; and (c) an effective amount of an organic or inorganic flame retardant synergistic compound; according to the improvement provided by the invention, further use is made as component (d) of an effective amount of an olefin polymer, an olefin copolymer or a mixture thereof, whereby a composition is obtained in which the decabromodiphenyl ether used as the flame retardant exhibits a reduced tendency to "settle out". after molding and thermal aging of the molded articles.

The term "normally high molecular weight flammable polyester" as used herein generally refers to linear saturated condensation products of diols and dicarboxylic acids or reactive derivatives thereof. Preferably these compounds are condensation products of aro 8000835

V

- 3 - dicarboxylic acids and aliphatic diols. It is of course also possible to use polyesters such as poly (1,4-dimethylolcyclohexane dicarboxylates), eg terephthalate *. In addition to phthalates, minor amounts of other aromatic dicarboxylic acids, such as naphthalene dicarboxylic acid, or aliphatic dicarboxylic acids, such as adipic acid, may also be present in preferred materials. Likewise, the diol can be varied by adding small amounts of cycloaliphatic diols in preferred embodiments. The preferred polyesters are known as film and fiber-forming materials, and can be obtained by methods described, inter alia, in U.S. Pat. Nos. 2,465,319 and 3,047,539. Preferred polyesters are poly (alkylene terephthalates isophthalates or mixed isophthalates terephthalates, e.g. with up to 30 mol% isophthalate), wherein the alkylene group contains 2-10 carbon atoms, e.g. poly (ethylene terephthalate) or poly (1, 4-butylene terephthalate). Because of its rapid melt crystallization, it is preferable to use poly (1,4-butylene terephthalate) as the normally flammable polyester resin in the present compositions.

The molecular weight of the polyester should be sufficiently high to provide an intrinsic viscosity of about 0.6-2.0 deciliter per gram and preferably 0.7-1.6 dl / g, e.g., determined as 1% 's solution' * in a mixture of phenol and tetrachloroethane (60:40) at 25 ° C.

In preferred embodiments, the polyester (component (a)) is straight or branched chain poly (1,4-butylene terephthalate), optionally in combination with poly (ethylene terephthalate) or in the form of a block copolyester with an aromatic-aliphatic or aliphatic-aliphatic polyester or in the form of a mixture with such a copolyester or in the form of a mixture with a resin selected from an aromatic polycarbonate, a polyacrylate, a polyacrylate modified with an aromatic vinyl compound, a copolymer of an aromatic vinyl compound and a diene, or a mixture of 2 or more of the above materials. These combinations and methods of preparing them are known.

As noted above, the flame retardant materials of the invention contain a conventional flame retardant synergistic component 35 (c), e.g., an organic or inorganic antimony compound, aluminum compound or molybdenum compound, or a mixture of two or more of these compounds. These compounds are widely available or can be prepared by known methods. In preferred embodiments, the synergist is an organic or inorganic antimony compound 8000835 → 4; the type of antimony compound used is not critical and the choice thereof is primarily based on economic considerations. Examples of inorganic antimony compounds to be used are antimony oxide (Sb ^ O ^); antimony phosphate; KSb (OH) / _; NH .SbS.; SbS_; and such. A wide variety of organic antimony compounds can also be used, eg antimony esters of organic acids; cyclic alkyl antimonites; arylantiomonic acids and the like. Examples of organic antimony compounds, including inorganic salts of these compounds, are: KSb tarrate; Sb capronate; Sb (OCH ^ CH ^) ^; Sb (OCH (CH ^) CH ^ CH ^) ^? Sb polymethylene-10 glyclolate; triphenylantimone; and such. Particular preference is given to antimony oxide.

The flame-retardant component decabromodiphenyl ether (b) can be prepared by known methods and / or is commercially available. Decabromodiphenyl ether is a white powder with a melting range of 300 ° -315 ° C, a theoretical bromine content of 83.3% and a specific gravity of 3.04 g / cm. This compound is marketed by Great Lakes Chemical Corporation under the designation "DE-83R".

The amount of decabromodiphenyl ether used as the flame retardant component (b) is not critical to the invention, provided that this compound is present in a small amount, based on the composition - large amounts are uneconomical and may impair formability, gloss and of such. However, one should use at least an amount sufficient to make the thermoplastic polyester resin flame retardant, non-flammable or self-extinguishing. Of course, the amount of component (b) varies depending on the nature of the flammable resin (s) and the relative effectiveness of the additive. In general, however, the amount of additive is 0.5-50 parts by weight. per part by weight. of the resins present as components. Preferably, the amount of component (b) is about 3-12 parts by weight. per 100 parts by weight of resin in the composition.

Likewise, the amount of the synergistic component (c) can vary within relatively wide limits, but generally about 0.5-20 parts by weight are used. preferably 1-12 parts by weight. synergistic compound per 100 parts by weight. resins in the composition.

Component (d) can vary widely in nature and type. Generally, any of the olefin polymers disclosed in U.S. Patent 3,957,757 can be used. Examples of suitable olefin polymers are polyethylene, polypropylene, polymers of butene-1 and butene-2, poly-4-methylpentene-1 and copolymers of ethylene and propylene, ethylene and butene and ethylene and 4-methylpentene-1. Also suitable are copolymers 8000835-5 - of ethylene and other unsaturated compounds such as vinyl esters of saturated carboxylic acids of 2-6 carbon atoms, acrylates and methacrylates of alcohols of 1-20 carbon atoms, acrylic acid, methacrylic acid, fumaric acid, maleic acid, and itaconic acid and esters of these carboxylic acids.

It is preferable to use polyethylene as component (d); the polyethylene can be linear or branched, and contain commonomers, e.g., vinyl acetate. The polyethylene can be selected from low density (0.910 ^ -0.925), medium density (0.926-0.940) or high density (0.941-0.965). In all cases, component (d) can be supplied in the form of a powder, granules, an emulsion or a concentrate, eg granules with weight% polyolefin or olefin copolymer in polyester resin, and the like. The polyolefins are available from a number of manufacturers.

A particularly suitable form of polyethylene is "Microthene FN-510", a product of U.S.I. Chemicals Co. Instead, one can also use Dow SI-4011769 PE 15 granules. The amount of polyolefin or olefin polymer (component (d)) can also vary within wide limits, e.g. about 0.1-25 parts by weight. and preferably about 0.5-10 parts by weight. per 100 parts by weight. of the total of components (a), (b), (c) and (d).

The invention also provides materials containing an effective amount of a conventional filler and / or reinforcing agent (e). Examples of fillers and / or reinforcing agents to be used are glass, talc, mica, clay or a mixture of two or more of these materials. Usual amounts of these materials are used, generally about 1-80 parts by weight. per 100 parts by weight. of the total composition. Glass fibers are particularly preferably used as filler and / or reinforcing component (e). Preferably about 7.5-40 parts by weight are used. glass per 100 parts by weight. of the total composition. According to the invention, the compositions may also contain other ingredients in conventional amounts for their usual purposes, such as mold release agents, pigments, stabilizers, nucleating agents and the like.

The manner of adding the flame retardant additives to the thermoplastic polyester resin is not critical; the additives can be added by known and conventional methods. Preferably, each ingredient is added as part of a "premix", and this "premix" is subjected to a mixing operation, eg by passing it through an extruder or rolling out, at a temperature that depends on the requirements of the composition in question.

The mixture can be cooled and brought into any desired shape. Representative processing and molding methods are explained below.

8000835 - 6 -

The materials of the invention can be used in many different final forms. They can be formed into 3-dimensional objects or into films or fibers by conventional methods, or extruded into rods, tubes, etc.

The preparation of certain materials according to the invention is illustrated in the following non-limiting examples.

Each tested composition was prepared in a Sterling extruder (4.45 cm) and the parts were molded in an 88.7 cm Dorn syringe molding machine at a molding temperature of about 66 ° C, a mouth-10. piece temperature of 271 ° C and a cylinder temperature of approximately 249 ° C.

Example I

A flame retardant material containing poly (1,4-butylene terephthalate), decabromodiphenyl ether, antimony oxide, stabilizer and polyolefin was prepared. A material without poly-15 olefin was prepared for comparison. The compositions and "bloom" (duplicate) weight loss are given in Table A below.

The weight loss due to "spreading" was determined with platelets of about 5.1 cm by about 7.6 cm by about 0.32 cm by the samples at 100 ° C and 170 ° C for 24 hours, 48 hours and 7 days subject to thermal aging. Decabromodiphenyl ether present on the surface was removed with chloroform and the total weight loss was determined. Each weight loss value was normalized and this assay repeated; weight loss is expressed as the percentage loss of total decabromodiphenyl ether content.

8000835% "- 7 - ΐ

Table Α Materials containing polyester, decabromodiphenyl ether, anti-moon oxide and polyolefin ._____ 1)

Example I IA

5 Composition (parts by weight)

Poly (1,4-butylene terephthalate) 83.3 84.8

Decabromodiphenyl ether 10.0 10.0 c)

Antimony oxide 5.0 5.0

Polyolefin ^ 1.5 10 Stabilizer (up to 100 parts by weight) - Properties

Decabromodiphenyl ether loss (%) at 100 ° C 24 hours 0.04 0.04 0.04 0.05 15 48 hours 0.06 0.07 0.06 0.07 7 days 0.08 0.12 0.12 0.12 at 170 ° C 24 hours 0.44 0.56 20 0.45 0.58 48 hours 0.63 0.85 0.60 0.85 7 days 1.06 1.42 1.07 1.43 25 _ 1) Control a) Valox 310, General Electric Company (b) DE-83R, Great Lakes Chemical Corporation (c) Chemetron 30 (d) Polyethylene, Microthene FN-510, ü.SI Chemicals.

The above clearly shows the significant improvement in "knockout" resistance.

Examples III-VIII

The general procedure of Example 1 was repeated, however, the type of polyolefin was varied and glass fibers were added to obtain reinforced flame-retardant materials and articles. The compositions used and the results obtained are set forth in Table B below.

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>> ωΛΡ (3 &) Ρ <& ιΛϋΜΗ> Λ m 8000835 - 10 - a) Valox 300, General Electric b), c), d (i); see footnotes to Table A d (ii) Dow SI 4001178 polyethylene granules d (iii) Dow SI 4011769 polyethylene granules 5 d (iv) 20% Microthene FN-510 in polybutylene terephthalate 1) Control

From the above, it appears that the addition of powdered "Microthene" in an amount of 1.5 parts by weight. gives an excellent reduction in the "result" (compare examples III and IV with examples UIA and IVA). "Microthene" in an amount of 0.1 parts by weight. gives only a marginal reduction of the "result" (V). Materials containing polyethylene grains (VII and VIII) and materials containing a 20% concentrate of "Microthene" (VI) give a "loss" reduction similar to that provided by polyethylene powder. These data might indicate that polyolefin itself and not its physical state (granules versus powder) is the determining factor in the reduction of the "efflorescence". This phenomenon may result from the polyolefin-rich surface of the formed workpieces which act as a barrier and reduce the loss of decabromodiphenyl ether. An interesting further observation was that samples exposed to a temperature of 170 ° C for a long time did not show "spread" continued. After a loss of approximately 1.6%, the samples showed no further signs of "knockout". This could indicate that "blowout" is a finite phenomenon and that the samples are not depleted of flame retardant from prolonged aging when using the invention.

Numerous variations are of course possible within the scope of the invention. For example, all of the poly (1,4-butylene terephthalate) or part of it can be replaced by a modification thereof branched with a small amount of pentaerythritol or forming a copolyester with a poly (hexylene adipienate co-iso-talate) .. Part or most of the resin can be replaced by poly (ethylene terephthalate) or poly (bisphenol-A carbonate). An additive to improve impact strength, e.g., poly (butyl acrylate), methyl methacrylate grafted butadiene-styrene, or a block copolymer of styrene and butadiene, optionally in combination with polycarbonate, may be used. Instead of polyethylene can be included in the composition polypropylene or an olefin copolymer, such as a copolymer of ethylene and vinyl acetate. It is also possible to use a segmented copolyester. of the type marketed by · Dupont under the name "Hydrel" resin.

40 The glass may be replaced in whole or in part by talc, mica, clay or a mixture of two or more of these materials.

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Claims (11)

A flame retardant thermoplastic material, containing (a) a normally flammable high molecular weight polyester; (b) a flame retardant amount of decabromodiphenyl ether; and (c) an effective amount of an organic or inorganic flame retardant synergistic compound, characterized by (d) an effective amount of an olefin polymer, an olefin copolymer or a mixture of 2 or more of these materials, wherein the composition after molding operations and thermal aging of the molded articles shows a reduced tendency of the flame retardant decabromodiphenyl ether to migrate to the surface ("blooming" or "plate-out"). 2. Material according to claim 1, characterized in that component (d) is polyethylene. Material according to claim 1 or 2, characterized in that the amount of component (b) is 3-12 parts by weight, the amount of component (c) is 1-12 parts by weight. and the amount of component (d) 0.5-10 parts by weight. per 100 parts by weight. of the composition. 4. Material according to claims 1-3, characterized in that the polyester (component (a)) is straight or branched chain poly (1,4-butylene terephthalate), which polyester may or may not be in combination with poly (ethylene terephthalate) ) or is present in the form of a block copolyester with an aromatic-aliphatic or aliphatic-aliphatic polyester or in the form of a mixture with such a copolyester or in the form of a mixture with an aromatic polycarbonate, a polyacrylate, a an aromatic vinyl compound modified polyacrylate, a copolymer of an aromatic vinyl compound and a diene, or a mixture of 2 or more of the above materials. Material according to claims 1-4, characterized in that component (c) is an organic or inorganic antimony, aluminum or molybdenum compound. Material according to claim 5, characterized in that component (c) is an organic or inorganic antimony-containing compound. Material according to claims 1-6, characterized in that component (d) is added in the form of a powder, granules or a pre-extruded concentrate. Material according to claims 1-7, characterized in that (e) an effective amount of a filler and / or reinforcing agent is also present. Material according to claim 8, characterized in that component 8000835 * - 12 - (e) is glass, talc, mica, clay or a mixture of 2 or more of these materials. Material according to claim 9, characterized in that component (e) is formed by glass fibers. Material according to claim 10, characterized in that the amount of glass fibers is about 7.5-40 parts by weight. per 100 parts by weight. of the material. o 3000835