Phenylphosphonate flame retardant compositions Description The present invention relates to flame retardant polymer compositions which comprise phen- ylphosphonates in combination with so-called sterically hindered nitroxyl derivatives. The compositions are especially useful for the manufacture of flame retardant compositions based on thermoplastic polymers, especially polyolefin homo- and copolymers and copolymers with vinyl monomers.

Flame retardants are added to polymeric materials (synthetic or natural) to enhance the flame retardant properties of the polymers. Depending on their composition, flame retardants may act in the solid, liquid or gas phase either chemically, e.g. as a spumescent by liberation of nitrogen, and/or physically, e.g. by producing a foam coverage. Flame retardants interfere during a particular stage of the combustion process, e.g. during heating, decomposition, igni- tion or flame spread.

There is still a need for flame retardant compositions with improved properties that can be used in different polymer substrates. Increased standards with regard to safety and environmental requirements result in stricter regulations. Particularly known halogen containing flame retardants no longer match all necessary requirements. Therefore, halogen free flame retardants are preferred, particularly in view of their better performance in terms of smoke density associated with fire. Improved thermal stability and less corrosive behaviour are further benefits of halogen free flame retardant compositions.

It has surprisingly been found that polymers with excellent flame retardant properties are prepared in the event that phenylphosphonate salts in combination with so-called sterically hindered amines are added to the polymer substrate. Moreover, flame dripping during the application of fire is significantly reduced.

Further benefits of the present invention are improved electrical properties (CTI = comparative tracking index) which cannot be achieved by using halogenated FR systems and less interactions with the polymer matrix during processing (reduced molecular weight decrease). Additionally, the flame retardants are resistant to so-called leaching. The contact with water does not diminish their flame retardant activity.

It has surprisingly been found that by use of the flame retardant compositions according to the invention halogen containing flame retardants, such as decabromodiphenyl oxide, antimony compounds, and fillers may largely be reduced or replaced. The invention relates to a composition, particularly a flame retardant composition, which comprises

a) A phenylphosphonate salt selected from the group consisting of

a') A melamine phenylphosphonate salt of the formula

b') A guanidine phenylphosphonate salt of the formula

Wherein

RrR ₅ independently of one another represent hydrogen or a substituent selected from the group consisting of CrC ₄ alkyl, hydroxy, hydroxy-CrC ₄ alkyl and

Ci-C ₄ alkoxy; and

R ₆ -Rg independently of one another represent hydrogen or a substituent selected from the group consisting of Ci-C ₄ alkyl, phenyl, phenyl-CrC ₄ alkyl, (d-C ₄ alk- yl)i _-3 phenyl and (Ci-C ₄ alkyl) _1-2 hydroxyphenyl; and

x represents a number between 1.0 and 2.0;

b) A tetraalkylpiperidine or tetralkylpiperazine derivative selected from the group that consists of 2,2,6,6-tetraalkylpiperidine-1-oxides, 1-hydroxy-2,2,6,6-tetraalkylpip- eridines, 1-alkoxy-2,2,6,6-tetraalkylpiperidines, 1-acyloxy-2,2,6,6-piperidines, 1-hy- droxy-2,2,6,6-tetraalkylpiperazines, 1 -alkoxy-2,2,6,6-tetraalkylpiperazines, and 1-acyloxy-2,2,6,6-piperazines; and

c) A polymer substrate.

The composition defined above for use as a flame retardant is another embodiment of the invention. A preferred embodiment of the invention relates to a composition, particularly a flame retar- dant composition, which comprises

a) A phenylphosphonate salt selected from the group consisting of

a') A melamine phenylphosphonate salt (I) and

b') A guanidine phenylphosphonate salt (II),

Wherein

RrR ₅ represent hydrogen; or

1-3 of RrR ₅ represent a substituent selected from the group consisting of Ci-C ₄ alkyl, hydroxy-Ci-C ₄ alkyl and Ci-C ₄ alkoxy; and the other ones repre- sent hydrogen; and

R ₆ -Rg independently of one another represent hydrogen or a substituent selected from the group consisting of CrC ₄ alkyl and phenyl; and x represents a number between 1.0 and 2.0;

b) A tetraalkylpiperidine derivative selected from the group that consists of 2,2,6,6- tetraalkylpiperidine-1 -oxides, 1-hydroxy-2,2,6,6-tetraalkylpiperidines, 1-alk- oxy-2,2,6,6-tetraalkylpiperidines and 1-acyloxy-2,2,6,6-piperidines; and c) A polymer substrate.

A more preferred embodiment of the invention relates to a composition, particularly a flame retardant composition, which comprises

a) A phenylphosphonate salt selected from the group consisting of

a') The melamine phenylphosphonate salt of the formula

Wherein x represents a number between 1.0 and 2.0; and b') The guanidine phenylphosphonate salt of the formula - A -

Wherein x represents a number between 1.0 and 2.0, and b) A tetraalkylpiperidine derivative selected from the group that consists of 2,2,6,6- tetraalkylpiperidine-1 -oxides, 1 -hydroxy-2,2,6,6-tetraalkylpiperidines, 1 - alkoxy-2,2,6,6-tetraalkylpiperidines and 1-acyloxy-2,2,6,6-piperidines; and c) A polymer substrate.

A specific embodiment of the invention relates to a composition, which comprises

a) A phenylphosphonate salt (I ¹ ) or (N');

b) A tetraalkylpiperidine derivative selected from the group consisting of 1-alk- oxy-2,2,6,6-tetraalkylpiperidines and 1-acyloxy-2,2,6,6-piperidines; and

c) A polymer substrate.

The compositions according to the invention exhibit excellent flame retardant properties. Dependent on the concentrations of components a) and b) in the polymer substrate, V-O or V-2 ratings according to UL-94 (Underwriter's Laboratories Subject 94) and other excellent rat- ings in related test methods are attained.

A particularly preferred embodiment of the invention relates to a composition, which comprises

a) A phenylphosphonate salt (I ¹ ) or (N');

b) A tetraalkylpiperidine derivative selected from the group consisting of 1-alk- oxy-2,2,6,6-tetraalkylpiperidines and 1-acyloxy-2,2,6,6-piperidines; and

c) A thermoplastic polymer.

The composition, as defined above, comprises the following components:

Component a)

In a melamine phenylphosphonate salt of the formula H ₂ N

RrR ₅ independently of one another represent hydrogen or a substituent selected from the group consisting of CrC ₄ alkyl, e.g. methyl, ethyl, n- or isopropyl, or n-, iso- or tert-butyl, hydroxy, hydroxy-Ci-C ₄ alkyl, e.g. hydroxymethyl or 1- or 2-hydroxyethyl and CrC ₄ alkoxy, e.g. methoxy or ethoxy; and x represents a number between 1.0 and 2.0.

In a guanidine phenylphosphonate salt of the formula

RrR ₅ are as defined above with regard to the phenylphosphonate salt (I);

R ₆ -Rg independently of one another represent hydrogen or a substituent selected from the group consisting of Ci-C ₄ alkyl, phenyl, phenyl-CrC ₄ alkyl, e.g. benzyl or 1-or 2-phenethyl, (Ci-C ₄ alkyl) _1-3 phenyl, e.g. tolyl or mesityl, and (Ci-C ₄ alkyl) _1-2 hydroxyphenyl, e.g. 4-hydroxy- 3,5-di-tert-butylphenyl or 3-tert-butyl-4-hydroxy-5-methylphenyl; and x represents a number between 1.0 and 2.0.

The melamine phenylphosphonate salt (I) and the guanidine phenylphosphonate salt (II), as defined above, are known compounds and are described in U.S. Pat. Spec. Nos. 4,061,605 (melamine phenylphosphonate salt (I)), and U.S. Pat. Spec. No. 4,308, 197 (guanidine phenylphosphonate salt (II).

The compositions of the invention contain the melamine phenylphosphonate salt (I) and the guanidine phenylphosphonate salt (II) as individual components or as a mixture or combina- tion of both.

These compounds are obtainable by known methods, e.g. acid-base reaction of equivalent amounts corresponding to x of phenylphosphonic acid of the formula

Wherein RrR ₅ are as defined above;

With melamine or a guanidine derivative of the formula

Or a salt thereof, e.g. the carbonate salt, wherein R ₆ -Rg are as defined above.

According to a preferred embodiment, melamine and guanidine phenylphosphonates are prepared from melamine or guanidine carbonate and phenylphosphinic acid, for example by addition of both components as hot aqueous solutions, followed by subsequent crystallization, filtration, drying, and milling.

A particularly preferred embodiment of the invention relates to compositions, particularly flame retardant compositions wherein the melamine phenylphosphonate salt of the formula

H ₂ N and the guanidine phenylphosphonate salt of the formula

are present.

In the melamine phenylphosphonate salt (I) and the guanidine phenylphosphonate salt (II) as defined above, the molar ratio of the phenylphosphonic acid and the melamine or guanidine base is between 1 :1 and 2:1 , corresponding to x being between 1 .0 and 2.0. Component a) is preferably contained in the flame retardant compositions according to the invention in an amount from 0.1 - 45.0 wt.%, preferably 0.1 - 30.0 wt.%, based on the weight of the polymer substrate component c), and component b) is preferably contained in an amount from 0.05 - 5.0 wt.%, preferably 0.1 - 2.0 wt.%. The preferred ratio of components a) : b) is in the range 50 : 1 - 1 : 5, preferably 20 : 1 - 1 : 2.

Component b)

A suitable tetraalkylpiperidine or tetralkylpiperazine derivative is selected from the group that consists of 2,2,6, 6-tetraalkylpiperidine-1 -oxides, 1-hydroxy-2,2,6,6-tetraalkylpiperidines, 1- alkoxy-2,2,6,6-tetraalkylpiperidines, 1 -acyloxy-2,2,6,6-piperidines, 1 -hydroxy-2,2,6,6-tetra- alkylpiperazines, 1-alkoxy-2,2,6,6-tetraalkylpiperazines, and 1-acyloxy-2,2,6,6-piperazines.

Such compounds can be illustrated by the partial formulae

Wherein R ₁ -R ₄ represent Ci-C ₄ alkyl, preferably methyl or ethyl. According to preferred embodiments, one of Ri and R ₂ and one of R ₃ of R ₄ represents ethyl and the other ones repre- sent methyl or all of R ₁ -R ₄ represent methyl; and

E represents hydrogen, CrC ₂ oalkyl, C ₅ -C ₆ cycloalkyl or C ₂ -C ₂ oalkyl, C ₅ -C ₆ cycloalkyl or C ₂ -C ₂₀ alkenyl with additional substituents; or represents the acyl group of a

CrC ₂₀ monocarboxylic or C ₂ -C ₂₀ dicarboxylic acid.

In the compounds that correspond to the partial formula a, one of the dotted lines in 4-posi- tion of the piperidine represents a bond to hydrogen or an N-substituent and the other one represents represents a bond to an O-substituent or a C-substituent.

In the alternative, both dotted lines in 4-position of the piperidine represent bonds to hydrogen, O-substituents or C-substituents or represent a double bond to oxygen.

In the compounds that correspond to the partial formula b, the nitrogen in 4-position of the piperazine is bonded to hydrogen or carbon-substituents.

Representative structural formulae are given below: [T ₃ ] _k

CO

J)

and

In these compounds (A) - (S):

E represents hydrogen, Ci-C ₂ oalkyl, C ₅ -C ₆ cycloalkyl or C ₂ -C ₂ oalkyl, C ₅ -C ₆ cycloalkyl or C ₂ -C ₂ oalkenyl with additional substituents; or represents the acyl group of a Ci-C ₂₀ mono- carboxylic or C ₂ -C ₂₀ dicarboxylic acid; or, in the alternative, the group >N-O-E is replaced with the group >N-O.

Alkyl is straight or branched and is for example methyl, ethyl, n-propyl, n-butyl, sec-butyl, tert-butyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n- tetradecyl, n-hexadecyl or n-octadecyl.

Cycloalkyl groups include cyclopentyl and cyclohexyl; typical cycloalkenyl groups include cyclohexenyl; while typical aralkyl groups include benzyl, alpha-methyl-benzyl, alpha, alpha- dimethylbenzyl or phenethyl.

E defined as the acyl group of a Ci-C ₂₀ monocarboxylic acid is preferably an acyl radical selected from the group consisting of -C(=O)-H, -C(=O)-Ci-Ci ₉ alkyl, -C(=O)-C ₂ -Ci ₉ alkenyl, -C(=O)-C ₂ -C ₄ alkenyl-C ₆ -Ci ₀ aryl, -C(=O)-C ₆ -Ci ₀ aryl, -C(=O)-O-Ci-C ₆ alkyl, -C(=O)-O-C ₆ -Ci ₀ aryl, -C(=O)-NH-Ci-C ₆ alkyl, -C(=O)-NH-C ₆ -Ci ₀ aryl and

-C(=O)-N(Ci-C ₆ alkyl) ₂ .

E defined as the acyl group of a C ₂ -C ₂ odicarboxylic acid is, for example, the diacyl radical derived from a monobasic organic acid having C radicals and two acid functions, e.g. a diacyl radical derived from an aliphatic, aromatic or cycloaliphatic dicarboxylic acid.

Suitable aliphatic dicarboxylic acids have from 2 to 40 C-atoms, e.g. oxalic acid, malonic acid, dimethylmalonic acid, succinic acid, pimelic acid, adipic acid, trimethyladipic acid, se- bacic acid, azelaic acid and dimeric acid (dimerization products of unsaturated aliphatic car- boxylic acids such as oleic acid), alkylated malonic and succinic acids, e.g. octadecylsuccinic acid.

Suitable cycloaliphatic dicarboxylic acids are, for example, 1 ,3-cyclobutanedicarboxylic acid, 1 ,3-cyclopentanedicarboxylic acid, 1 ,3- and 1 ,4-cyclohexanedicarboxylic acid, 1 ,3- and 1 ,4- (dicarboxymethyl)cyclohexane or 4,4'-dicyclohexyldicarboxylic acid.

Preferred members of this group include the acyl radical of oxalic acid, adipic acid, succinic acid, suberic acid, sebacic acid, phthalic acid dibutylmalonic acid, dibenzylmalonic acid or butyl-(3,5-di-tert-butyl-4-hydropxybenzyl)-malonic acid, or bicycloheptenedicarboxylic acid, with succinates, sebacates, phthalates and isophthalates being specific examples.

If E is a divalent acyl radical of a dicarbamic acid, it is for example an acyl radical of hexa- methylenedicarbamic acid or of 2,4-toluylenedicarbamic acid;

T is a straight or branched chain alkylene of 1 to 18 C-atoms, cycloalkylene of 5 to 18

C-atoms, cycloalkenylene of 5 to 18 C-atoms, a straight or branched chain alkylene of 1 to 4 C-atoms substituted by phenyl or by phenyl substituted by one or two alkyl groups of 1 to 4 C-atoms;

b is 1 , 2 or 3 with the proviso that b does not exceed the number of C-atoms in T, and when b is 2 or 3, each hydroxyl group is attached to a different C-atoms of T;

R is hydrogen or methyl; and

m is 1 to 4.

In the compounds mentioned above when the variable m is 1 ,

R ₂ is hydrogen, Ci-Ciβalkyl or said alkyl optionally interrupted by one or more oxygen atoms, C ₂ -Ci ₂ alkenyl, C ₆ -Ci ₀ aryl, C ₇ -Ci ₈ aralkyl, glycidyl, the monovalent acyl radical of an aliphatic, cycloaliphatic or aromatic carboxylic acid, or a carbamic acid, for example an acyl radical of an aliphatic carboxylic acid having 2-18 C-atoms, of a cycloaliphatic carboxylic acid having 5-12 C-atoms or of an aromatic carboxylic acid having 7-15 C-atoms, or represents groups of the partial formulae

wherein x is 0 or 1 ,

wherein y is 2-4;

When m is 2,

R ₂ is Ci-Ci ₂ alkylene, C ₄ -Ci ₂ alkenylene, xylylene, a divalent acyl radical of an aliphatic, cyclo- aliphatic, araliphatic or aromatic dicarboxylic acid or of a dicarbamic acid, for example an acyl radical of an aliphatic dicarboxylic acid having 2-18 C-atoms, of a cycloaliphatic or aromatic dicarboxylic acid having 8-14 C-atoms, or of an aliphatic, cycloaliphatic or aromatic dicarbamic acid having 8-14 C-atoms;

Or represents groups of the partial formulae

Wherein

D ₁ and D ₂ are independently hydrogen, CrC ₈ alkyl, aryl or aralkyl including the 3,5-di-t-butyl- 4-hydroxybenzyl radical;

D ₃ is hydrogen, d-Ci ₈ alkyl or CrC ₂₀ alkenyl; and

d is 0-20; When m is 3,

R ₂ is a trivalent acyl radical of an aliphatic, unsaturated aliphatic, cycloaliphatic, or aromatic tricarboxylic acid;

When m is 4,

R ₂ is a tetravalent acyl radical of a saturated or unsaturated aliphatic or aromatic tetracarb- oxylic acid including 1 ,2,3,4-butanetetracarboxylic acid, 1 ,2,3,4-but-2-enetetracarboxylic , and 1 ,2,3,5- and 1 ,2,4,5-pentanetetracarboxylic acid;

In the compounds mentioned above when the variable p is 1 , 2 or 3,

R ₃ is hydrogen, Ci-Ci ₂ alkyl, C ₅ -C ₇ cycloalkyl, C ₇ -C ₉ aralkyl, C ₂ -Ci ₈ alkanoyl, C ₃ -C ₅ alkenoyl or benzoyl;

When p is 1 ,

R ₄ is hydrogen, CrCi ₈ alkyl, C ₅ -C ₇ cycloalkyl, C ₂ -C ₈ alkenyl, unsubstituted or substituted by cyano, carbonyl or carbamide, or is aryl, aralkyl, or glycidyl, a group of the partial formula -CH ₂ -CH(OH)-Z or of the partial formulae -CO-Z or -CONH-Z, wherein Z is hydrogen, methyl or phenyl, or represents groups of the partial formulae

where h is 0 or 1 ;

R ₃ and R ₄ together, when p is 1 , represents alkylene of 4 to 6 C-atoms, or 2-oxo-polyal- kylene, or the cyclic acyl radical of an aliphatic or aromatic 1 ,2- or 1 ,3-dicarboxylic acid;

When p is 2, R ₄ is a direct bond or is d-C^alkylene, C ₆ -Ci ₂ arylene, xylylene, a -CH ₂ CH(OH)-CH ₂ group or a group of the partial formula -CH ₂ -CH(OH)-CH ₂ -O-X-O-CH ₂ -CH(OH)-CH ₂ -, wherein X is C ₂ -Ci ₀ alkylene, C ₆ -Ci ₅ arylene or C ₆ -Ci ₂ cycloalkylene; or, provided that R ₃ is other than alk- anoyl, alkenoyl or benzoyl, R ₄ additionally represents the divalent acyl radical of an aliphatic, cycloaliphatic or aromatic dicarboxylic acid or dicarbamic acid, or represents the group -CO-; or

R ₄ represents a group of the partial formula

where T ₈ and T ₉ are independently hydrogen, CrCi ₈ alkyl, or T ₈ and T ₉ together represent C ₄ -C ₈ alkylene or 3-oxapentamethylene, for instance T ₈ and T ₉ together are 3-oxapentame- thylene;

When p is 3,

R ₄ is 2,4,6-triazinyl;

n is 1 or 2;

When n is 1 ,

R ₅ and R' ₅ are independently Ci-Ci ₂ alkyl, C ₂ -Ci ₂ alkenyl, C ₇ -Ci ₂ aralkyl, or R ₅ additionally represents hydrogen, or R ₅ and R' ₅ together are C ₂ -C ₈ alkylene or hydroxyalkylene or C ₄ - C ₂₄ acyloxyalkylene;

When n is 2,

R ₅ and R' ₅ together are a group of the partial formula (-CH ₂ ) ₂ C(CH ₂ -) ₂ ;

R ₆ is hydrogen, Ci-Ci ₂ alkyl, allyl, benzyl, glycidyl or C ₂ -C ₆ alkoxyalkyl; or

When n is 1 ,

R ₇ is hydrogen, Ci-Ci ₂ alkyl, C ₃ -C ₅ alkenyl, C ₇ -C ₉ aralkyl, C ₅ -C ₇ cycloalkyl, C ₂ -C ₄ hydroxyalkyl, C ₂ -C ₆ alkoxyalkyl, C ₆ -Ci ₀ aryl, glycidyl, a group of the partial formula -(CH ₂ ) _t -C00-Q or of the partial formula -(CH ₂ ) _t -0-C0-Q wherein t is 1 or 2, and Q is Ci-C ₄ alkyl or phenyl; or when n is 2,

R ₇ is C ₂ -Ci ₂ alkylene, C ₆ -Ci ₂ arylene, a group of the partial formula -CH ₂ CH(OH)-CH ₂ -O-X-O-CH ₂ -CH(OH)-CH ₂ -,

Wherein X is C ₂ -Ci ₀ alkylene, C ₆ -Ci ₅ arylene or C ₆ -Ci ₂ cycloalkylene, or a group of the partial formula

-CH ₂ CH(OZ')CH ₂ -(OCH ₂ -CH(OZ')CH ₂ ) ₂ -,

Wherein Z' is hydrogen, CrCi ₈ alkyl, allyl, benzyl, C ₂ -Ci ₂ alkanoyl or benzoyl;

Q ₁ is -N(R ₈ )- or -O-; E ₇ is CrC ₃ alkylene, the group -CH ₂ -CH(Rg)-O- wherein R ₉ is hydrogen, methyl or phenyl, the group -(CH ₂ ) ₃ -NH- or a direct bond;

Rio is hydrogen or Ci-Ci ₈ alkyl, R ₈ is hydrogen, Ci-Ci ₈ alkyl, C ₅ -C ₇ cycloalkyl, C ₇ -Ci ₂ aralkyl, cyanoethyl, C ₆ -C _1o aryl, the group -CH ₂ -CH(Rg)-OH wherein R ₉ has the meaning defined above; or represents groups of the partial formulae

CC - OR ₀

Wherein G ₄ is C ₂ -C ₆ alkylene or C ₆ -Ci ₂ arylene; or R ₈ is a group of the partial formula

Formula F denotes a recurring structural unit of a polymer where T ₃ is ethylene or 1 ,2-pro- pylene, is the repeating structural unit derived from an alpha-olefin copolymer with an alkyl acrylate or methacrylate; for example a copolymer of ethylene and ethyl acrylate, and where k is 2 to 100;

T ₄ has the same meaning as R ₄ when p is 1 or 2;

T ₅ is methyl;

T ₆ is methyl or ethyl, or T ₅ and T ₆ together are tetramethylene or pentamethylene, for instance T ₅ and T ₆ are each methyl;

M and Y are independently methylene or carbonyl, and T ₄ is ethylene where n is 2;

T ₇ is as defined as R ₇ , and T ₇ is for example octamethylene where n is 2;

Tio and T ₁₁ are independently alkylene of 2 to 12 C-atoms; Or T ₁₁ represents a group of the partial formula

N .\ N

N

T ₁₂ is piperazinyl, or represents groups of the partial formulae

-NR ₁₁ -(CH ₂ )^NR ₁₁ - Or _ _NR(C H ₂₎ _ _N(CH2) _ _N[(C H ₂₎ . _{N] H}

a b c f where R ₁₁ is as defined as R3 or additionally represents a group of the partial formula

a, b and c are independently 2 or 3, and f is 0 or 1 , for instance a and c are each 3, b is 2 and f is 1 ; and

e is 2, 3 or 4, for example 4;

T ₁₃ is the same as R ₂ with the proviso that T ₁₃ is other than hydrogen when n is 1 ;

0 E ₁ and E ₂ , being different, each are -CO- or -N(E ₅ )- where E ₅ is hydrogen, CrC ₁₂ alkyl or C ₄ - C ₂₄ alkoxycarbonylalkyl, for instance E ₁ is -CO- and E ₂ is -N(E ₅ )-;

E ₃ is hydrogen, CrC ₃₀ alkyl, phenyl, naphthyl, said phenyl or said naphthyl substituted by chlorine or by Ci-C ₄ alkyl, or C ₇ -C ₁₂ phenylalkyl, or said phenylalkyl substituted by CrC ₄ alkyl ;

E ₄ is hydrogen, alkyl of 1 to 30 C-atoms, phenyl, naphthyl or phenylalkyl of 7 to 12 C-atoms,5 or

E ₃ and E ₄ together are polymethylene of 4 to 17 C-atoms, or said polymethylene substituted by up to four CrC ₄ alkyl groups, for example methyl;

E ₆ is an aliphatic or aromatic tetravalent radical;

R ₂ of formula (N) is a previously defined when m is 1 ;

0 G ₁ a direct bond, C ₁ -C ₁₂ alkylene, phenylene or -NH-G'-NH wherein G' is C ₁ -C ₁₂ alkylene. Suitable tetraalkylpiperidine or tetralkylpiperazine derivatives are, for example, compounds of the formulae 1-12:

wherein

E ₁ , E ₂ , E ₃ and E ₄ are independently d-C ₄ alkyl, or E ₁ and E ₂ are independently CrC ₄ alkyl and E ₃ and E ₄ taken together are pentamethylene, or E ₁ and E ₂ ; and E ₃ and E ₄ each taken together are pentamethylene;

R ₁ is CrC ₁₈ alkyl, C ₅ -C ₁₂ cycloalkyl, a bicyclic or tricyclic hydrocarbon radical of 7 to 12 carbon atoms, C ₇ -C ₁₅ phenylalkyl, C ₆ -C ₁₀ aryl or said aryl substituted by one to three CrC ₈ alkyl;

R ₂ is hydrogen or a linear or branched chain C ₁ -C ₁₂ alkyl;

R ₃ is alkylene of 1 to 8 carbon atoms, or R ₃ is -CO-, -CO-R ₄ -, -CONR ₂ -, or -CO-NR ₂ -R ₄ -;

R ₄ is C ₁ -C ₈ alkylene;

R ₅ is hydrogen, linear or branched chain CrC ₁₂ alkyl, or represents a group of the partial formula

Or, when R ₄ is ethylene, two R ₅ methyl substituents can be linked by a direct bond with the triazine bridging group -N(R ₅ )-R ₄ -N(R ₅ )- forming a piperazin-1 ,4-diyl group;

R ₆ is C ₂ -C ₈ alkylene or represents a group of the partial formula

with the proviso that Y is other than -OH when R ₆ is the structure depicted above;

A is -O- or -NR ₇ - where R ₇ is hydrogen, straight or branched chain Ci-Ci ₂ alkyl; or R ₇ is a group of the partial formula

T is phenoxy, phenoxy substituted by one or two Ci-C ₈ alkyl or d-C ₈ alkoxy or -N(R ₂ ) ₂ with the stipulation that R ₂ is other than hydrogen; or T is a group of the partial formula

X is -NH ₂ , -NCO, -OH, -O-glycidyl, or -NHNH ₂ , and

Y is -OH, -NH ₂ , -NHR ₂ where R ₂ is other than hydrogen; or Y is -NCO, -COOH, oxiranyl, -O-glycidyl, or -Si(OR ₂ ) ₃ ;

Or the combination R ₃ -Y- is -CH ₂ CH(OH)R ₂ where R ₂ is alkyl or said alkyl interrupted by one to four oxygen atoms, or R ₃ -Y- is -CH ₂ OR ₂ ; or

Wherein the hindered amine compound is a mixture of N,N',N"'-tris{2,4-bis[(1-hydrocarb- yloxy-2,2,6,6-tetramethylpiperidin-4-yl)alkylamino]-s-triazi n-6-yl}-3,3'-ethylenediiminodipropyl- amine; N,N',N"-tris{2,4-bis[(1-hydrocarbyloxy-2,2,6,6-tetramethylpi peridin-4-yl)alkylamino]-s- triazin-6-yl}-3,3'-ethylenediiminodipropylamine, and bridged derivatives as described by formulae

R ₁ NH-CH ₂ CH ₂ CH ₂ NR ₂ CH ₂ CH ₂ NR ₃ CH ₂ CH ₂ CH ₂ NH R ₄ (13)

T-E ₁ -T ₁ (14) T-E ₁ (15)

G-E ₁ -G ₁ -E ₁ -G ₂ (16)

Where in the tetraamine (13)

R ₁ and R ₂ are the s-triazine moiety E; and one of R ₃ and R ₄ is the s-triazine moiety E with the other ones of R ₃ or R ₄ being hydrogen;

E is

R is methyl, propyl, cyclohexyl or octyl, for instance cyclohexyl;

R ₅ is CrC ₁₂ alkyl, for example n-butyl;

where in the compound of formula (14) and (15), when R is propyl, cyclohexyl or octyl,

T and T ₁ are each a tetraamine substituted by R ₁ -R ₄ as is defined for formula 13, where

(1 ) One of the s-triazine moieties E in each tetraamine is replaced by the group E ₁ which forms a bridge between two tetraamines T and T ₁ ;

E ₁ is a group of the partial formula

(2) The group E ₁ can have both termini in the same tetraamine T as in formula 15, where two of the E moieties of the tetraamine are replaced by one E ₁ group; or (3) All three s-triazine substituents of tetraamine T can be E ₁ such that one E ₁ links T and T ₁ and a second E ₁ has both termini in tetraamine T;

L is propanediyl, cyclohexanediyl or octanediyl;

Where in the compound (16)

G, G ₁ and G ₂ are each tetraamines substituted by R ₁ -R ₄ as defined for formula I, except that G and G ₂ each have one of the s-triazine moieties E replaced by E ₁ , and G ₁ has two of the triazine moieties E replaced by E ₁ , so that there is a bridge between G and G ₁ and a second bridge between G ₁ and G ₂ ;

which mixture is prepared by reacting two to four equivalents of 2,4-bis[(1 -hydrocarbyloxy- 2,2,6,6-tetramethylpiperidin-4-yl)butylamino]-6-chloro-s-tri azine with one equivalent of N, N'- bis(3-aminopropyl)ethylenediamine;

Or the hindered amine is a compound of the formula (17)

In which the index n ranges from 1 to 15;

R ₁₂ is C ₂ -C ₁₂ alkylene, C ₄ -C ₁₂ alkenylene, C ₅ -C ₇ cycloalkylene, C ₅ -C ₇ cycloalkylene-di(Cr C ₄ alkylene), CrC ₄ alkylene-di(C5-C ₇ cycloalkylene), phenylene-di(CrC ₄ alkylene) or

C ₄ -C ₁₂ alkylene interrupted by 1 ,4-piperazinediyl, -O- or ^-X ₁ with X ₁ being CrC ₁₂ acyl or

(C-i-C ₁₂ alkoxy)carbonyl or having one of the definitions of R ₁₄ given below other than hydrogen; or R ₁₂ is a group of the partial formulae:

With X ₂ being Ci-Ci ₈ alkyl, C ₅ -Ci ₂ cycloalkyl which is unsubstituted or substituted by 1 , 2 or 3 Ci-C ₄ alkyl; phenyl which is unsubstituted or substituted by 1 , 2 or 3 Ci-C ₄ alkyl or d- C ₄ alkoxy; Cr-Cgphenylalkyl which is unsubstituted or substituted on the phenyl by 1 , 2 or 3 Ci-C ₄ alkyl; and

The radicals X ₃ being independently of one another C ₂ -Ci ₂ alkylene;

Ri ₃ , Ri ₄ and Ri ₅ , which are identical or different, are hydrogen, CrCi ₈ alkyl, C ₅ -Ci ₂ cycloalkyl which is unsubstituted or substituted by 1 , 2 or 3 CrC ₄ alkyl; C ₃ -Cisalkenyl, phenyl which is unsubstituted or substituted by 1 , 2 or 3 Ci-C ₄ alkyl or Ci-C ₄ alkoxy; C ₇ -C ₉ phenylalkyl which is unsubstituted or substituted on the phenyl by 1 , 2 or 3 CrC ₄ alkyl; tetrahydrofurfuryl or

C ₂ -C ₄ alkyl which is substituted in the 2, 3 or 4 position by -OH, Ci-Csalkoxy,

di(CrC ₄ alkyl)amino or a group of the partial formula;

Y N - with Y being -O-, -CH ₂ -, -CH ₂ CH ₂ - or >N-CH ₃ , or -N(Ri ₄ )(Ri ₅ ) is additionally the group ^γ N -

The radicals A are independently of one another -ORi ₃ , -N(Ri ₄ )(Ri ₅ ) or a group of the partial formula:

H ₃ C CH ₃

Wherein

X is -O- or >N-Ri ₆ ; Ri ₆ is hydrogen, Ci-Ci ₈ alkyl, C ₃ -Ci ₈ alkenyl, C ₅ -Ci ₂ cycloalkyl which is unsubstituted or substituted by 1 , 2 or 3 CrC ₄ alkyl; Cr-Cgphenylalkyl which is unsubstituted or substituted on the phenyl by 1 , 2 or 3 Ci-C ₄ alkyl; tetrahydrofurfuryl, a group of the partial formula:

or C ₂ -C ₄ alkyl which is substituted in the 2, 3 or 4 position by -OH, d-C ₈ alkoxy, di(C _r

C ₄ alkyl)amino or the group of the partial formula CH ₃ ,

Rn has one of the definitions given for R ₁₆ ; and

the radicals B have independently of one another one of the definitions given for A.

The tetraalkylpiperidine and tetraalkylpiperazine compounds are known in the art, also known as N-alkoxy hindered amines and NOR-hindered amines or NOR-hindered amine light stabilizers or NOR-HALS, such as the ones disclosed in U.S. Pat. Spec. Nos. 5,004,770, 5,204,473, 5,096,950, 5,300,544, 5, 112,890, 5, 124,378, 5, 145,893, 5,216, 156, 5,844,026, 6, 117,995 or 6,271,377.

U.S. Pat. Spec. No. 6,271,377, and Published U.S. Application Nos. 09/505,529, filed Feb. 17, 2000, and 09/794,710, filed Feb. 27, 2001 disclose hindered hydroxyalkoxyamine stabilizers. Hindered hydroxyalkoxyamine stabilizers are also known as N-hydroxyalkoxy hindered amines, or NORoI-HALS.

Representative structures are the following:

Wherein the definitions of R and R' include N-, O- or C-substituents. When the group E is -O-C(O)-Ci-Ci ₈ alkyl, the compounds are hydroxylamine esters.

The hydroxylamines are reacted with an acid derivative to form the final hydroxylamine ester. Such esterification processes are known and described in the literature.

The preparation of particularly suitable compounds is described in the International Patent Application WO 01/90113.

According to a preferred embodiment, the tetraalkylpiperidine derivative is selected from the group of 2,2,6, 6-tetraalkylpiperidine-1 -oxides of the formula

1-hydroxy-2,2,6,6-tetraalkylpiperidines of the formula

1-alkoxy-2,2,6,6-tetraalkylpiperidines of the formula

1 -acyloxy-2,2,6,6-piperidines of the formula

Wherein

One of R ₃ and R _b represents

Hydrogen or an N-substituent and the other one represents an O-substituent or a C- substituent; or Both R _a and R _b represent hydrogen, O-substituents or C-substituents;

R represents Ci-C ₂ oalkyl, C ₅ -C ₆ cycloalkyl or C ₂ -C ₂ oalkyl, C ₅ -C ₆ cycloalkyl or C ₂ -C ₂₀ alk- enyl with additional substituents;

Ac represents the acyl group of a Ci-C ₂₀ monocarboxylic or CrC ₂₀ dicarboxylic acid; and R ₁ -R ₄ each represent d-C ₄ alkyl; and

R ₅ and Re, independently of one another, represent hydrogen or a substituent selected from the group consisting of Ci-C ₄ -alkyl, d-C ₃ alkylphenyl and phenyl; and

R ₅ and R ₆ together represent oxo.

According to a preferred embodiment, the composition comprises as Component b) at least one tetraalkylpiperidine derivative III a, III b, III c or III d,

Wherein

One of R ₃ and R _b represents

Hydrogen or an N-substituent and the other one represents an O-substituent or a C- substituent; or

Both R ₃ and Rb represent hydrogen, O-substituents or C-substituents;

R represents Ci-C ₈ alkyl, C ₅ -C ₆ cycloalkyl or C ₂ -C ₈ alkyl, C ₅ -C ₆ cycloalkyl or C ₂ -C ₈ alkenyl with additional substituents;

Ac represents the acyl group of a Ci-C ₈ carboxylic acid; and

RrR ₄ are each methyl; and

R ₅ and R ₆ each represent hydrogen.

According to a particularly preferred embodiment, the composition comprises as Component b) at least one tetraalkylpiperidine derivative III a, III b, III c or III d,

Wherein

One of R ₃ and R _b represents

Hydrogen or an N-substituent and the other one represents an O-substituent or a C- substituent; or

Both R ₃ and Rb represent O-substituents or C-substituents; R represents CrC ₈ alkyl, C ₅ -C ₆ cycloalkyl or C ₂ -C ₈ alkyl, C ₅ -C ₆ cycloalkyl or C ₂ -C ₈ alkenyl substituted by hydroxy;

Ac represents the acyl group of a Ci-C ₈ carboxylic acid; and

R ₁ -R ₄ are each methyl; and

R ₅ and R ₆ each represent hydrogen.

According to a preferred embodiment, Component b) consists of at least one tetraalkyl- piperidine derivative III c or III d selected from the group consisting of

1-Cyclohexyloxy-2,2,6,6-tetramethyl-4-octadecylaminopiperidi ne,

bis(1-Octyloxy-2,2,6,6-tetramethylpiperidin-4-yl)sebacate,

2,4-bis[(1 -Cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)butylamino] -6-(2-hydroxy- ethylamino-s-triazine,

bis(1-Cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl) adipate,

2,4-bis[(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)b utylamino]-6-chloro-s-tri- azine,

1 -(2-Hydroxy-2-methylpropoxy)-4-hydroxy-2,2,6,6-tetramethylpi peridine,

1-(2-Hydroxy-2-methylpropoxy)-4-oxo-2,2,6,6-tetramethylpiper idine,

1-(2-Hydroxy-2-methylpropoxy)-4-octadecanoyloxy-2,2,6,6-tetr amethylpiperidine, bis(1-(2-Hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperid in-4-yl) sebacate, bis(1-(2-Hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperid in-4-yl) adipate, 2,4-bis{N-[1-(2-Hydroxy-2-methylpropoxy)-2,2,6,6-tetramethyl piperidin-4-yl]-N-butyl- amino}-6-(2-hydroxyethylamino)-s-triazine,

The reaction product of 2,4-bis[(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)- butylamino]-6-chloro-s-triazine with N,N'-bis(3-aminopropyl)ethylenediamine), 2,4-bis[(1-Cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)b utylamino]-6-(2-hydroxy- ethylamino-s-triazine,

The oligomeric compound which is the condensation product of 4,4'-hexamethylene- bis(amino-2,2,6,6-tetramethylpiperidine) and 2,4-dichloro-6-[(1 -cyclohexyloxy-2,2,6,6- tetramethylpiperidin-4-yl)butylamino]-s-triazine end-capped with 2-chloro-4,6- bis(dibutylamino)-s-triazine,

The compound of the formula

And the compound of the formula

in which n is from 1 to 15.

The above mentioned compounds are partly items of commerce. Representative compounds are marketed by Ciba under the following trade names Flamestab NOR 1 16®, Tinuvin NOR 371® or lrgatec CR 76®.

Component b) is preferably contained in the flame retardant compositions according to the invention in an amount from 0.01 - 10.0 wt.-%, based on the weight of the polymer substrate Component c), more preferably in an amount from 0.1 - 9.0 wt.-% and most preferably in an amount from 0.25 - 3.0 wt.-%.

Component c)

The term polymer substrate comprises within its scope thermoplastic polymers or thermo- sets. A list of suitable thermoplastic polymers is given below:

1. Polymers of monoolefins and diolefins, for example polypropylene, polyisobutylene, poly- but-1-ene, poly-4-methylpent-1-ene, polyvinylcyclohexane, polyisoprene or polybutadi- ene, as well as polymers of cycloolefins, for instance of cyclopentene or norbornene, polyethylene (which optionally can be cross linked), for example high density polymethyl- ene (HDPE), high density and high molecular weight polyethylene (HDPE-HMW), high density and ultrahigh molecular weight polyethylene (HDPE-UHMW), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), (VLDPE) and (ULDPE).

Polyolefins, i.e. the polymers of monoolefins exemplified in the preceding paragraph, preferably polyethylene and polypropylene, can be prepared by different and especially by the following methods:

a) Radical polymerisation (normally under high pressure and at elevated temperature). b) Catalytic polymerisation using a catalyst that normally contains one or more than one metal of groups IVb, Vb, VIb or VIII of the Periodic Table. These metals usually have one or more than one ligand, typically oxides, halides, alcoholates, esters, ethers, amines, alkyls, alkenyls and/or aryls that may be either π- or σ-bond coordinated. These metal complexes may be in the free form or fixed on substrates, typically on activated magnesium chloride, titanium(lll) chloride, alumina or silicon oxide. These catalysts may be soluble or insoluble in the polymerisation medium. The catalysts can be used by themselves in the polymerisation or further activators may be used, typically metal alkyls, metal hydrides, metal alkyl halides, metal alkyl oxides or metal alkyloxanes, said metals being elements of groups Ia, Na and/or Ilia of the Periodic Table. The activators may be modified conveniently with further ester, ether, and amine or silyl ether groups. These catalyst systems are usually termed Phillips, Standard Oil

Indiana, Ziegler-Natta), TNZ (DuPont), metallocene or single site catalysts (SSC).

2. Mixtures of the polymers mentioned under 1 ), for example mixtures of polypropylene with polyisobutylene, polypropylene with polyethylene (for example PP/HDPE, PP/LDPE) and mixtures of different types of polyethylene (for example LDPE/HDPE).

3. Copolymers of monoolefins and diolefins with each other or with other vinyl monomers, for example ethylene/propylene copolymers, linear low density polyethylene (LLDPE) and mixtures thereof with low density polyethylene (LDPE), propylene/but-1-ene copolymers, propylene/isobutylene copolymers, ethylene/but-1-ene copolymers, ethylene/hexene copolymers, ethylene/methylpentene copolymers, ethylene/heptene copolymers, ethyl- ene/octene copolymers, ethylene/vinylcyclohexane copolymers, ethylene/cycloolefin copolymers (e.g. ethylene/norbornene like COC), ethylene/1 -olefins copolymers, where the 1 -olefin is generated in-situ; propylene/butadiene copolymers, isobutylene/isoprene copolymers, ethylene/vinylcyclohexene copolymers, ethylene/alkyl acrylate copolymers, ethylene/alkyl methacrylate copolymers, ethylene/vinyl acetate copolymers or ethyl- ene/acrylic acid copolymers and their salts (ionomers) as well as terpolymers of ethylene with propylene and a diene such as hexadiene, dicyclopentadiene or ethylidene-no- rbornene; and mixtures of such copolymers with one another and with polymers mentioned in 1 ) above, for example polypropylene/ethylene-propylene copolymers, LDPE/- ethylene-vinyl acetate copolymers (EVA), LDPE/ethylene-acrylic acid copolymers (EAA),

LLDPE/EVA, LLDPE/EAA and alternating or random polyalkylene/carbon monoxide copolymers and mixtures thereof with other polymers, for example polyamides.

4. Hydrocarbon resins (for example C ₅ -Cg) including hydrogenated modifications thereof (e.g. tackifiers) and mixtures of polyalkylenes and starch;

The homopolymers and copolymers mentioned above may have a stereo structure including syndiotactic, isotactic, hemi-isotactic or atactic; where atactic polymers are preferred. Stereo block polymers are also included.

5. Polystyrene, poly(p-methylstyrene), poly(α-methylstyrene).

6. Aromatic homopolymers and copolymers derived from vinyl aromatic monomers including styrene, α-methylstyrene, all isomers of vinyl toluene, especially p-vinyl toluene, all isomers of ethyl styrene, propyl styrene, vinyl biphenyl, vinyl naphthalene, and vinyl anthracene, and mixtures thereof. Homopolymers and copolymers may have a stereo structure including syndiotactic, isotactic, hemi-isotactic or atactic; where atactic polymers are preferred. Stereo block polymers are also included;

a) Copolymers including aforementioned vinyl aromatic monomers and comonomers selected from ethylene, propylene, dienes, nitriles, acids, maleic anhydrides, maleimides, vinyl acetate and vinyl chloride or acrylic derivatives and mixtures thereof, for example styrene/butadiene, styrene/acrylonitrile, styrene/ethylene (interpolymers), styrene/alkyl methacrylate, styrene/butadiene/alkyl acrylate, sty- rene/butadiene/alkyl methacrylate, styrene/maleic anhydride, styrene/acryloni- trile/methyl acrylate; mixtures of high impact strength of styrene copolymers and another polymer, for example a polyacrylate, a diene polymer or an ethylene/pro- pylene/diene terpolymer; and block copolymers of styrene such as styrene/buta- diene/styrene, styrene/isoprene/styrene, styrene/ethylene/butylene/styrene or sty- rene/ethylene/propylene/styrene.

b) Hydrogenated aromatic polymers derived from hydrogenation of polymers mentioned under 6.), especially including polycyclohexylethylene (PCHE) prepared by hydrogenating atactic polystyrene, often referred to as polyvinylcyclohexane

(PVCH).

c) Hydrogenated aromatic polymers derived from hydrogenation of polymers mentioned under 6a). Homopolymers and copolymers may have a stereo structure including syndiotactic, isotactic, hemi-isotactic or atactic; where atactic polymers are preferred. Stereo block polymers are also included.

7. Graft copolymers of vinyl aromatic monomers such as styrene or α-methylstyrene, for example styrene on polybutadiene, styrene on polybutadiene-styrene or polybutadiene- acrylonitrile copolymers; styrene and acrylonitrile (or methacrylonitrile) on polybutadiene; styrene, acrylonitrile and methyl methacrylate on polybutadiene; styrene and maleic an- hydride on polybutadiene; styrene, acrylonitrile and maleic anhydride or maleimide on polybutadiene; styrene and maleimide on polybutadiene; styrene and alkyl acrylates or methacrylates on polybutadiene; styrene and acrylonitrile on ethylene/propylene/diene terpolymers; styrene and acrylonitrile on polyalkyl acrylates or polyalkyl methacrylates, styrene and acrylonitrile on acrylate/butadiene copolymers, as well as mixtures thereof with the copolymers listed under 6), for example the copolymer mixtures known as ABS,

MBS, ASA or AES polymers.

8. Halogen-containing polymers such as polychloroprene, chlorinated rubbers, chlorinated and brominated copolymer of isobutylene-isoprene (halobutyl rubber), chlorinated or sul- phochlorinated polyethylene, copolymers of ethylene and chlorinated ethylene, epichloro- hydrin homo- and copolymers, especially polymers of halogen-containing vinyl compounds, for example polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, polyvi- nylidene fluoride, as well as copolymers thereof such as vinyl chloride/vinylidene chloride, vinyl chloride/vinyl acetate or vinylidene chloride/vinyl acetate copolymers.

9. Polymers derived from α,β-unsatu rated acids and derivatives thereof such as polyacry- lates and polymethacrylates; polymethyl methacrylates, polyacrylamides and polyacry- lonitriles, impact-modified with butyl acrylate.

10. Copolymers of the monomers mentioned under 9) with each other or with other unsaturated monomers, for example acrylonitrile/ butadiene copolymers, acrylonitrile/alkyl aery- late copolymers, acrylonitrile/alkoxyalkyl acrylate or acrylonitrile/vinyl halide copolymers or acrylonitrile/ alkyl methacrylate/butadiene terpolymers.

1 1. Polymers derived from unsaturated alcohols and amines or the acyl derivatives or acetals thereof, for example polyvinyl alcohol, polyvinyl acetate, polyvinyl stearate, polyvinyl ben- zoate, polyvinyl maleate, polyvinyl butyral, polyallyl phthalate or polyallyl melamine; as well as their copolymers with olefins mentioned in 1 above.

12. Homopolymers and copolymers of cyclic ethers such as polyalkylene glycols, polyethylene oxide, polypropylene oxide or copolymers thereof with bisglycidyl ethers.

13. Polyacetals such as polyoxymethylene and those polyoxymethylenes, which contain ethylene oxide as a co-monomer; polyacetals modified with thermoplastic polyurethanes, acrylates or MBS.

14. Polyphenylene oxides and sulphides, and mixtures of polyphenylene oxides with styrene polymers or polyamides.

15. Polyurethanes derived from hydroxyl-terminated polyethers, polyesters or polybutadienes on the one hand and aliphatic or aromatic polyisocyanates on the other, as well as precursors thereof.

16. Polyamides and co-polyamides derived from diamines and dicarboxylic acids and/or from aminocarboxylic acids or the corresponding lactams, for example polyamide 4, polyam- ide 6, polyamide 6/6, 6/10, 6/9, 6/12, 4/6, 12/12, polyamide 11 , polyamide 12, aromatic polyamides starting from m-xylene diamine and adipic acid; polyamides prepared from hexamethylenediamine and isophthalic or/and terephthalic acid and with or without an elastomer as modifier, for example poly-2,4,4,-trimethylhexamethylene terephthalamide or poly-m-phenylene isophthalamide; and also block copolymers of the aforementioned polyamides with polyolefins, olefin copolymers, ionomers or chemically bonded or grafted elastomers; or with polyethers, e.g. with polyethylene glycol, polypropylene glycol or poly- tetramethylene glycol; as well as polyamides or co-polyamides modified with EPDM or ABS; and polyamides condensed during processing (RIM polyamide systems).

17. Polyureas, polyimides, polyamide imides, polyether imides, polyester imides, polyhydan- toins and polybenzimidazoles.

18. Polyesters derived from dicarboxylic acids and diols and/or from hydroxycarboxylic acids or the corresponding lactones, for example polyethylene terephthalate, polybutylene ter- ephthalate, poly-1 ,4-dimethylolcyclohexane terephthalate, polyalkylene naphthalate (PAN) and polyhydroxybenzoates, as well as block co-polyether esters derived from hydroxy l-term in ated polyethers; and also polyesters modified with polycarbonates or MBS.

19. Polyketones.

20. Polysulphones, polyether sulphones and polyether ketones.

21. Blends of the aforementioned polymers (polyblends), for example PP/EPDM, Polyam- ide/EPDM or ABS, PVC/EVA, PVC/ABS, PVC/MBS, PC/ABS, PBTP/ABS, PC/ASA, PC/PBT, PVC/CPE, PVC/acrylates, POM/thermoplastic PUR, PC/thermoplastic PUR, POM/acrylate, POM/MBS, PPO/HIPS, PPO/PA 6.6 and copolymers, PA/HDPE, PA/PP, PA/PPO, PBT/PC/ABS or PBT/PET/PC.

22. Polycarbonates that correspond to the general formula:

Such Polycarbonates are obtainable by interfacial processes or by melt processes (catalytic transesterification). The polycarbonate may be either branched or linear in structure and may include any functional substituents. Polycarbonate copolymers and polycarb- onate blends are also within the scope of the invention. The term polycarbonate should be interpreted as inclusive of copolymers and blends with other thermoplastics. Methods for the manufacture of polycarbonates are known, for example, from U.S. Patent Specification Nos. 3,030,331; 3, 169, 121; 4, 130,458; 4,263,201; 4,286,083; 4,552, 704;

5,210,268; and 5,606,007. A combination of two or more polycarbonates of different molecular weights may be used.

Preferred are polycarbonates obtainable by reaction of a diphenol, such as bisphenol A, with a carbonate source. Examples of suitable diphenols are:

Bisphenol A: , bisphenol AF:

bisphenol AP: . H O ^0H , bisphenol B: bisphenol C: bisphenol E: /r OH

bisphenol F: , bisphenol M:

bisphenol P:

bisphenol S: bisphenol TMC:

bisphenol Z: , 4,4'-(2-norbornylidene)bis(2,6-dichlorophe- nol); or fluorene-9-bisphenol:

The carbonate source may be a carbonyl halide, a carbonate ester or a haloformate. Suitable carbonate halides are phosgene or carbonylbromide. Suitable carbonate esters are dialkylcarbonates, such as dimethyl- or diethylcarbonate, diphenyl carbonate, phenyl- alkylphenylcarbonate, such as phenyl-tolylcarbonate, dialkylcarbonates, such as dimethyl- or diethylcarbonate, di-(halophenyl)carbonates, such as di-(chlorophenyl)carbonate, di-(bromophenyl)carbonate, di-(trichlorophenyl)carbonate or di-(trichlorophenyl)carbon- ate, di-(alkylphenyl)carbonates, such as di-tolylcarbonate, naphthylcarbonate, dichloro- naphthylcarbonate and others. The polymer substrate mentioned above, which comprises polycarbonates or polycarbonate blends is a polycarbonate-copolymer, wherein isophthalate/terephthalate-resorci- nol segments are present. Such polycarbonates are commercially available, e.g.

Lexan® SLX (General Electrics Co. USA). Other polymeric substrates of component b) may additionally contain in the form as admixtures or as copolymers a wide variety of synthetic polymers including polyolefins, polystyrenes, polyesters, polyethers, polyami- des, poly(meth)acrylates, thermoplastic polyurethanes, polysulphones, polyacetals and PVC, including suitable compatibilizing agents. For example, the polymer substrate may additionally contain thermoplastic polymers selected from the group of resins consisting of polyolefins, thermoplastic polyurethanes, styrene polymers and copolymers thereof.

Specific embodiments include polypropylene (PP), polyethylene (PE), polyamide (PA), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), glycol-modified polycyclohexylenemethylene terephthalate (PCTG), polysulphone (PSU), polymethylmethacrylate (PMMA), thermoplastic polyurethane (TPU), acrylonitrile-butadiene-styrene (ABS), acrylonitrile-styrene-acrylic ester (ASA), acrylonitrile-ethylene-propylene-styrene

(AES), styrene-maleic anhydride (SMA) or high impact polystyrene (HIPS).

23. Epoxy resins consisting of a di- or polyfunctional epoxide compound, wherein at least two epoxy groups of the partial formula

are present, which are attached directly to carbon, oxygen, nitrogen or sulphur atoms, and wherein q represents zero, Ri and R ₃ both represent hydrogen and R ₂ represents hydrogen or methyl; or wherein q represents zero or 1 , R ₁ and R ₃ together form the -CH ₂ -CH ₂ - Or -CH ₂ -CH ₂ -CH ₂ - groups and R ₂ represents hydrogen.

Suitable hardener components are, for example, amine and anhydride hardeners such as polyamines, e.g. ethylenediamine, diethylenetriamine, triethylenetriamine, hexamethyl- enediamine, methanediamine, N-aminoethyl piperazine, diaminodiphenylmethane [DDM], alkyl-substituted derivatives of DDM, isophoronediamine [IPD], diaminodiphenylsulphone [DDS], 4,4'-methylenedianiline [MDA], or m-phenylenediamine [MPDA]), polyamides, al- kyl/alkenyl imidazoles, dicyandiamide [DICY], 1 ,6-hexamethylene-bis-cyanoguanidine, or acid anhydrides, e.g. dodecenylsuccinic acid anhydride, hexahydrophthalic acid anhydride, tetrahydrophthalic acid anhydride, phthalic acid anhydride, pyromellitic acid anhydride, and derivatives thereof. A preferred embodiment of the invention relates to compositions which comprise as component c) thermoplastic polymers. Preferred thermoplastic polymers include polyolefin homo- and copolymers, copolymers of olefins vinyl monomers, styrenic homopolymers and copolymers thereof.

Advantageously, the melamine and guanidine salts (I) and (II) are ground to a fine powder with an average particle size below 100 μm prior to their application in polymer substrates as it is observed that the flame retardant properties of the inventive compositions are improved by small particle sizes.

Additional Components

The instant invention further pertains to a composition, which comprises, in addition to the components a), b) and c), as defined above, as optional components, additional flame retar- dants and further additives selected from the group consisting of so-called anti-dripping agents and polymer stabilizers.

Representative phosphorus containing flame retardants are for example:

Tetraphenyl resorcinol diphosphate (Fyrolflex ^® RDP, Akzo Nobel), resorcinol diphosphate oligomer (RDP), triphenyl phosphate, tris(2,4-di-tert-butylphenyl)phosphate, ethylenediamine diphosphate (EDAP), ammonium polyphosphate, diethyl-N,N-bis(2-hydroxyethyl)-amino- methyl phosphonate, hydroxyalkyl esters of phosphorus acids, salts of di-Ci-C ₄ alkylphos- phinic acids and of hypophosphoric acid (H ₃ PO ₂ ), particularly the Ca ²⁺ , Zn ²⁺ , Or AI ³⁺ salts, tetrakis(hydroxymethyl)phosphonium sulphide, triphenylphosphine, derivatives of 9,10-dihy- dro-9-oxa-10-phosphorylphenanthrene-10-oxide (DOPO), and phosphazene flame-retar- dants.

Nitrogen containing flame retardants are, for example, isocyanurate flame retardants, such as polyisocyanurate, esters of isocyanuric acid or isocyanurates. Representative examples are hydroxyalkyl isocyanurates, such as tris-(2-hydroxyethyl)isocyanurate, tris(hydroxy- methyl)isocyanurate, tris(3-hydroxy-n-proyl)isocyanurate or triglycidyl isocyanurate.

Nitrogen containing flame-retardants include further melamine-based flame-retardants. Representative examples are: melamine cyanurate, melamine borate, melamine phosphate, melamine pyrophosphate, melamine polyphosphate, melamine ammonium polyphosphate, melamine ammonium pyrophosphate, dimelamine phosphate and dimelamine pyrophosphate.

Further examples are: benzoguanamine, tris(hydroxyethyl) isocyanurate, allantoin, glycoluril, melamine cyanurate, melamine phosphate, dimelamine phosphate, urea cyanurate, ammo- nium polyphosphate, a condensation product of melamine from the series melem, melam, melon and/or a higher condensed compound or a reaction product of melamine with phosphoric acid or a mixture thereof.

Representative organohalogen flame retardants are, for example:

Polybrominated diphenyl oxide (DE-60F, Great Lakes Corp.), decabromodiphenyl oxide (DBDPO; Saytex ^® 102E), tris[3-bromo-2,2-bis(bromomethyl)propyl] phosphate (PB 370 ^® , FMC Corp.), tris(2,3-dibromopropyl)phosphate, tris(2,3-dichloropropyl)phosphate, chlorendic acid, tetrachlorophthalic acid, tetrabromophthalic acid, poly-β-chloroethyl triphosphonate mixture, tetrabromobisphenol A bis(2,3-dibromopropyl ether) (PE68), brominated epoxy resin, ethylene-bis(tetrabromophthalimide) (Saytex ^® BT-93), bis(hexachlorocyclopentadieno)cyclo- octane (Declorane Plus ^® ), chlorinated paraffins, octabromodiphenyl ether, hexachlorocyclo- pentadiene derivatives, 1 ,2-bis(tribromophenoxy)ethane (FF680), tetrabromo-bisphenol A (Saytex ^® RB100), ethylene bis-(dibromo-norbornanedicarboximide) (Saytex ^® BN-451 ), bis- (hexachlorocycloentadeno) cyclooctane, PTFE, tris-(2,3-dibromopropyl)-isocyanurate, and ethylene-bis-tetrabromophthalimide.

The organohalogen flame retardants mentioned above are routinely combined with an inorganic oxide synergist. Most common for this use are zinc or antimony oxides, e.g. Sb ₂ Os or Sb ₂ O ₅ . Boron compounds are suitable, too.

Representative inorganic flame retardants include, for example, aluminum trihydroxide (ATH), boehmite (AIOOH), magnesium dihydroxide (MDH), zinc borates, CaCOβ, (organically modified) layered silicates, (organically modified) layered double hydroxides, and mixtures thereof.

The above-mentioned additional flame retardant classes are advantageously contained in the composition of the invention in an amount from about 0.5% to about 60.0% by weight of the organic polymer substrate; for instance about 1.0% to about 40.0%; for example about 5.0% to about 35.0% by weight of the polymer or based on the total weight of the composition.

According to another embodiment, the invention relates to a composition which additionally comprises as additional component so-called anti-dripping agents.

These anti-dripping agents reduce the melt flow of the thermoplastic polymer and inhibit the formation of drops at high temperatures. Various references, such as U.S. Patent Specification No. 4,263,201, describe the addition of anti-dripping agents to flame retardant compositions. Suitable additives that inhibit the formation of drops at high temperatures include glass fibers, polytetrafluoroethylene (PTFE), high temperature elastomers, carbon fibers, glass spheres and the like.

The addition of polysiloxanes of different structures has been proposed in various refer- ences; cf . U. S. Pat. Spec. Nos. 6, 660, 787, 6, 727, 302 or 6, 730, 720.

Stabilizers are preferably halogen-free and selected from the group consisting of nitroxyl stabilizers, nitrone stabilizers, amine oxide stabilizers, benzofuranone stabilizers, phosphite and phosphonite stabilizers, quinone methide stabilizers and monoacrylate esters of 2,2'-alky- lidenebisphenol stabilizers.

As mentioned above, the composition according to the invention may additionally contain one or more conventional additives, for example selected from pigments, dyes, plasticizers, antioxidants, thixotropic agents, levelling assistants, basic co-stabilizers, metal passivators, metal oxides, organophosphorus compounds, further light stabilizers and mixtures thereof, especially pigments, phenolic antioxidants, calcium stearate, zinc stearate, UV absorbers of the 2-hydroxy-benzophenone, 2-(2'-hydroxyphenyl)benzotriazole and/or 2-(2-hydroxyphenyl)- 1 ,3,5-triazine groups.

Preferred additional additives for the compositions as defined above are processing stabilizers, such as the above-mentioned phosphites and phenolic antioxidants, and light stabilizers, such as benzotriazoles. Preferred specific antioxidants include octadecyl 3-(3,5-di-tert-butyl- 4-hydroxyphenyl) propionate (IRGANOX 1076), pentaerythritol-tetrakis[3-(3,5-di-tert-butyl-4- hydroxyphenyl)propionate] (IRGANOX 1010), tris(3,5-di-tert-butyl-4-hydroxyphenyl)iso- cyanurate (IRGANOX 31 14), 1 ,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl) ben- zene (IRGANOX 1330), triethyleneglycol-bis[3-(3- tert-butyl-4-hydroxy-5-methylphenyl)propi- onate] (IRGANOX 245), and N,N'-hexane-1 ,6-diyl-bis[3-(3,5-di-tert-butyl-4-hydroxyphen- yl)propionamide] (IRGANOX 1098). Specific processing stabilizers include tris(2 ,4-d i-tert- butylphenyl)phosphite (IRGAFOS 168), 3,9-bis(2,4-di-tert-butylphenoxy)-2,4,8,10-tetraoxa- 3,9-diphosphaspiro[5.5]undecane (IRGAFOS 126), 2,2',2"-nitrilo[triethyl-tris(3,3',5,5'-tetra- tert-butyl-1 ,1 '-biphenyl-2,2'-diyl)]phosphite (IRGAFOS 12), and tetrakis(2,4-di-tert-butylphen- yl)[1 ,1-biphenyl]-4,4'-diylbisphosphonite (IRGAFOS P-EPQ). Specific light stabilizers include 2-(2H-benzotriazole-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phe nol (TINUVIN 234), 2-(5-chloro- (2H)-benzotriazole-2-yl)-4-(methyl)-6-(tert-butyl)phenol (TINUVIN 326), 2-(2H-benzotriazole- 2-yl)-4-(1 ,1 ,3,3-tetramethylbutyl)phenol (TINUVIN 329), 2-(2H-benzotriazole-2-yl)-4-(tert-but- yl)-6-(sec-butyl)phenol (TINUVIN 350), 2,2'-methylenebis(6-(2H-benzotriazol-2-yl)-4-(1 , 1 ,3,3- tetramethylbutyl)phenol) (TINUVIN 360), and 2-(4,6-diphenyl-1 ,3,5-triazin-2-yl)-5-[(hexyl)- oxy]-phenol (TINUVIN 1577), 2-(2'-hydroxy-5'-methylphenyl)benzotriazole (TINUVIN P), 2- hydroxy-4-(octyloxy)benzophenone (CHIMASSORB 81 ), 1 ,3-bis-[(2'-cyano-3',3'-diphenyl- acryloyl)oxy]-2,2-bis-{[(2'-cyano- 3',3'-diphenylacryloyl)oxy]methyl}-propane (UVINUL 3030, BASF), ethyl-2-cyano-3,3-diphenylacrylate (UVINUL 3035, BASF), and (2-ethylhexyl)-2- cyano-3,3-diphenylacrylate (UVINUL 3039, BASF).

The additives mentioned above are preferably contained in an amount of 0.01 to 10.0%, especially 0.05 to 5.0%, relative to the weight of the polymer substrate of Component c).

The incorporation of the components defined above into the polymer component is carried out by known methods such as dry blending in the form of a powder, or wet mixing in the form of solutions, dispersions or suspensions for example in an inert solvent, water or oil. The addi- tive components a) and b) and optional further additives may be incorporated, for example, before or after molding or also by applying the dissolved or dispersed additive or additive mixture to the polymer material, with or without subsequent evaporation of the solvent or the suspension/dispersion agent. They may be added directly into the processing apparatus (e.g. extruders, internal mixers, etc.), e.g. as a dry mixture or powder, or as a solution or dispersion or suspension or melt.

The addition of the additive components to the polymer substrate can be carried out in customary mixing machines in which the polymer is melted and mixed with the additives. Suitable machines are known to those skilled in the art. They are predominantly mixers, kneaders and extruders.

The process is preferably carried out in an extruder by introducing the additive during processing.

Particularly preferred processing machines are single-screw extruders, contra-rotating and co-rotating twin-screw extruders, planetary-gear extruders, ring extruders or co-kneaders. Processing machines provided with at least one gas removal compartment can be used to which a vacuum can be applied.

Suitable extruders and kneaders are described, for example, in Handbuch der Kunststoffex- trusion, Vol. 1 Grundlagen, Editors F. Hensen, W. Knappe, H. Potente, 1989, pp. 3-7, ISBN:3-446-14339-4 (Vol. 2 Extrusionsanlagen 1986, ISBN 3-446-14329-7).

For example, the screw length is 1 - 60 screw diameters, preferably 35-48 screw diameters. The rotational speed of the screw is preferably 10 - 600 rotations per minute (rpm), preferably 25 - 300 rpm.

The maximum throughput is dependent on the screw diameter, the rotational speed and the driving force. The process of the present invention can also be carried out at a level lower than maximum throughput by varying the parameters mentioned or employing weighing machines delivering dosage amounts.

If a plurality of components is added, these can be premixed or added individually.

The additive components a) and optional further additives can also be sprayed onto the poly- mer substrate b). The additive mixture dilutes other additives, for example the conventional additives indicated above, or their melts so that they can be sprayed also together with these additives onto the polymer substrate. Addition by spraying during the deactivation of the polymerisation catalysts is particularly advantageous; in this case, the steam evolved may be used for deactivation of the catalyst. In the case of spherically polymerised polyolefins it may, for example, be advantageous to apply the additives of the invention, optionally together with other additives, by spraying.

The additive components a) and b) optional further additives can also be added to the polymer in the form of a master batch ("concentrate") which contains the components in a concentration of, for example, about 1.0% to about 40.0% and preferably 2.0% to about 20.0% by weight incorporated in a polymer. The polymer is not necessarily of identical structure than the polymer where the additives are added finally. In such operations, the polymer can be used in the form of powder, granules, solutions, and suspensions or in the form of lattices.

Incorporation can take place prior to or during the shaping operation. The materials containing the additives of the invention described herein preferably are used for the production of molded articles, for example roto-molded articles, injection molded articles, profiles and the like, and especially a fibre, spun melt non-woven, film or foam.

A particularly preferred embodiment of the invention relates to a composition, which comprises

a) The phenylphosphonate salt (I ¹ ) or (M');

b) At least one tetraalkylpiperidine derivative III c or III d selected from the group consisting of

1-Cyclohexyloxy-2,2,6,6-tetramethyl-4-octadecylaminopiperidi ne,

bis(1 -Octyloxy-2,2,6,6-tetramethylpiperidin-4-yl) sebacate,

2,4-bis[(1-Cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)b utylamino]-6-(2-hy- droxyethylamino-s-triazine,

bis(1-Cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl) adipate,

2,4-bis[(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)b utylamino]-6-chloro-s- triazine, 1-(2-Hydroxy-2-methylpropoxy)-4-hydroxy-2,2,6,6-tetramethylp iperidine,

1-(2-Hydroxy-2-methylpropoxy)-4-oxo-2,2,6,6-tetramethylpi peridine,

1-(2-Hydroxy-2-methylpropoxy)-4-octadecanoyloxy-2,2,6,6-t etramethylpiperidine, bis(1-(2-Hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperid in-4-yl) sebacate, bis(1 -(2-Hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperidin-4- yl) adipate,

2,4-bis{N-[1-(2-Hydroxy-2-methylpropoxy)-2,2,6,6-tetramet hylpiperidin-4-yl]-N-bu- tylamino}-6-(2-hydroxyethylamino)-s-triazine,

The reaction product of 2,4-bis[(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)- butylamino]-6-chloro-s-triazine with N,N'-bis(3-aminopropyl)ethylenediamine), 2,4-bis[(1 -Cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)butylamino] -6-(2-hy- droxyethylamino-s-triazine,

The oligomeric compound which is the condensation product of 4,4'-hexamethyle- nebis(amino-2,2,6,6-tetramethylpiperidine) and 2,4-dichloro-6-[(1 -cyclohexyloxy- 2,2,6,6-tetramethylpiperidin-4-yl)butylamino]-s-triazine end-capped with 2-chloro- 4,6-bis(dibutylamino)-s-triazine,

The compound of the formula

And the compound of the formula

in which n is from 1 to 15.; and

c) A polymer substrate selected from the group consisting of polyfunctional epoxide compounds, hardener compounds and thermoplastic polymers.

A further embodiment of the invention relates to a mixture, which comprises

a) A phenylphosphonate salt selected from the group consisting of

a') A melamine phenylphosphonate salt (I) and

b') A guanidine phenylphosphonate salt (II)

Wherein

R ₁ -R5 independently of one another represent hydrogen or a substituent selected from the group consisting of CrC ₄ alkyl, hydroxy, hydroxy-CrC ₄ alkyl and Ci-C ₄ alkoxy; and

R ₆ -Rg independently of one another represent hydrogen or a substituent selected from the group consisting of Ci-C ₄ alkyl, phenyl, phenyl-CrC ₄ alkyl, (Ci-C ₄ alkyl) _1-3 phenyl and (Ci-C ₄ alkyl) _1-2 hydroxyphenyl; and x represents a number between 1.0 and 2.0; and

b) A tetraalkylpiperidine derivative selected from the group that consists of 2,2,6,6- tetraalkylpiperidine-1 -oxides, 1 -hydroxy-2,2,6,6-tetraalkylpiperidines, 1 -alk- oxy-2,2,6,6-tetraalkylpiperidines and 1 -acyloxy-2,2,6,6-piperidines. The components a) and b) are admixed to the polymer substrate c) in concentrations of 0.1 - 45.0 wt.%, preferably 0.1 - 30.0 wt.% for component a) and 0.05 - 5.0 wt.%, preferably 0.1 - 2.0 wt.% for component b).

The preferred ratio of components a) : b) is in the range 50 : 1 - 1 : 5, preferably 20 : 1 - 1 : 2.

A further embodiment of the invention relates to a process for imparting flame retardancy to a polymer substrate, which process comprises adding to a polymer substrate of component c) the above defined mixture of components a) and b).

The following examples illustrate the invention, but are not to be construed to limit the scope thereof.

Examples

Components and Reagents used

Moplen® HF500 N: Commercial polypropylene (Basell, Germany)

BB 412 E: Commercial polypropylene block copolymer (Borealis AG, Austria)

Melamine: Commercial product (DSM, Netherlands)

Guanidine carbonate: Commercial product (Merck Eurolab, Germany)

Phenylphosphonic acid: Commercial product (Aldrich, Germany)

Tinuvin® NOR 371 (NOR 1 ): Commercial product (Ciba Inc., Switzerland)

Flamestab® NOR 1 16 (NOR 2): Commercial product (Ciba Inc., Switzerland)

2,4,6-Tris(1 -methoxy-2,2,6,6-tetramethylpiperidin-4-yloxy)-1 ,3,5-triazine (NOR 3) obtainable according to U.S. Patent Specification 5,019,613

Bis(1-propoxy-2,2,6,6-tetramethylpiperidyl)-4-diazene (NOR 4) obtainable according to WO 2008/101845.

Preparation of Phenylphosphonic Acid Salts Example A: Preparation of melamine phenylphosphonate

Melamine (2.0 mol, 252.0 g) is dispersed in 2.50 1 deionized water and heated to 95°C. To this dispersion, phenylphosphonic acid (2.00 mol, 316.0 g) is added in small portions under vigorous stirring. After completing the addition, the reaction mixture is stirred for another 90 min at 95°C and then allowed to cool to 60 ⁰ C. The formed crystals are filtered off at 60 ⁰ C and dried at 130 ⁰ C in vacuum. 514.0 g (1.81 mol, 90.4%) of the product is obtained as a colorless solid with a decomposition temperature of 281 ⁰ C (onset).

Elemental analysis for C ₉ H ₁₃ N ₆ O ₃ P (284.22) P(calcd.): 10.9%; P(found): 10.7%.

Example B: Preparation of guanidine phenylphosphonate

Guanidine carbonate (1.25 mol, 225.0 g) is dispersed in 250 ml deionized water and heated to 50 ⁰ C. A saturated solution of phenylphosphonic acid (2.50 mol, 395 g) in water at 50°C is prepared and added in small portions to this dispersion under vigorous stirring. After completing the addition, the reaction mixture is stirred for another 90 min at 50 ⁰ C and then allowed to cool to room temperature. The solution is poured into 3 1 acetone, and the precipitate is filtered off and dried at 130°C in vacuum. 520.0 g (2.39 mol, 95.7%) of the product is obtained as a colorless solid having a melting point at 140 ⁰ C and a decomposition temperature of 275°C (onset).

Example C: Preparation of diguanidine phenylphosphonate

Guanidine carbonate (1.39 mol, 250.0 g) is dispersed in 250 ml deionized water and heated to 95°C. A solution of phenylphosphonic acid (1.39 mol, 220.0 g) in 100 ml water at 70°C is prepared and added in small portions under vigorous stirring. After completing the addition, the reaction mixture is stirred for another 30 min at 95°C and allowed to cool to room temperature. The formed crystals are filtered off and dried at 130 ⁰ C under vacuum. 350.0 g (1.27 mol, 91.2%) of the product is obtained as a colorless solid with a decomposition tem- perature of 259°C (onset).

Test methods to assess flame retardancy

UL 94 test for "Flammability of Plastic Materials for Parts in Devices and Appliances" , 5 ^th edition, October 29, 1996. Ratings according to the UL 94 V test are compiled in the following table (time periods are indicated for one specimen):

n.c: No classification

Preparation of Polymeric Compositions

Melamine and guanidine salts prepared according to examples A-C are ground and sieved using a 120 μm sieve. Prior to use the resultant powders are dried in a vacuum oven at 80 ⁰ C over night.

Extrusion

Referential Examples 1-5 and Inventive Examples 1-7: Polypropylene homopolymer

(MOPLEN HF 500 N) is extruded on a co-rotating twin-screw extruder ZSK25 (Coperion Werner & Pfleiderer) at a temperature of T _max : 230 ⁰ C, a throughput rate of 4 kg/h and a rotational speed of 100 rotations per minute (rpm). To MOPLEN HF 500 N are added basic-level stabilization (0.05% Ca-stearate + 0.5% IRGANOX® B225; IRGANOX® B225 is a 1 :1 mixture of I RGAFOS® 168 and IRGANOX® 1010) and the additives listed in Table 1.

Referential Examples 6-12 and Inventive Examples 8-12: Polypropylene homopolymer (MOPLEN HF 500 N) is extruded on a co-rotating twin-screw extruder ZSK18 (Coperion

Werner & Pfleiderer) at a temperature of T _max : 230°C, a throughput rate of 2 kg/h and a rotational speed of 100 rotations per minute (rpm). To MOPLEN HF 500 N are added basic-level stabilization (0.05% Ca-stearate + 0.3% IRGANOX® B225; IRGANOX® B225 is a 1 :1 mixture of IRGAFOS® 168 and IRGANOX® 1010) and the additives indicated in Tables 3 and 4. Referential Examples 13-15 and Inventive Examples 13-14: Polypropylene block copolymer (BB 412 E) is extruded on a co-rotating twin-screw extruder ZSK25 (Coperion Werner & Pfleiderer) at a temperature of T _max : 250 ⁰ C, a throughput rate of 4 kg/h and a rotational speed of 100 rotations per minute (rpm) without use of additional stabilizers and with the additives indicated in Table 5. After cooling in a water bath, the polymer strand is granulated. UL94-V test specimen (bars 125x12.5 mm, thickness = 1.6 mm) and 1.0 mm plaques according to DIN 4102-B2 are prepared by injection molding on an Arburg 370S injection molding machine at 230 ⁰ C. Films according to DIN 4102-B2 are obtained by compression molding.

Testing of Polymeric Compositions

The test samples are investigated for their flame retardant behavior in accordance with UL94-V standards after conditioning for 48 h at 23 ⁰ C and 50% relative humidity.

Additional UL94-V tests are performed after exposure of the test specimen to deionized water at 70 ⁰ C for a period of 7 days (leaching test). Subsequently, the test bars are dried in a vacuum oven at 105 °C for 24 h. Results obtained after leaching are presented in Table 2.

Table 1

UL94 V (1.6 mm) test results obtained with polypropylene homopolymer containing different flame retardant compositions

^a) Number of tests (out of five tests) in which burning drips dripping from the ignited test bar ignite cotton placed underneath the test bar according to the UL94 test norm.

It can be concluded from the results reported above that the polymer compositions according to the present invention show excellent flame retardancy with self-extinguishing properties. While none of the referential compositions comprising a single additive show significant flame retardant behavior, the inventive combinations of a phosphonate salt and a representative sterically hindered N-alkoxyamine provide very efficient flame retardancy. Further benefits of the present invention are improved mechanical properties due to low loading levels of flame retardants.

Table 2

Properties and UL94 V (1.6 mm) results of polypropylene homopolymer test bars containing inventive flame retardant compositions after leaching in deionized water at 70 ⁰ C for 7 days.

a ⁾ Number of tests (out of five tests) in which burning drips dripping from the ignited test bar ignite cotton placed underneath the test bar according to the UL94 test norm.

It can be concluded from the results presented in Table 2 that the polymer compositions according to the present invention are characterized by their excellent leaching resistance against water. Essentially no weight loss and no change of sample thickness are observed after leaching tests. Inventive Example 4 shows that UL94 V-O rating is retained during leaching tests. Table 3

Test results according to DIN 4102-B2 (flame size: 40 mm) obtained with 200 μm films of polypropylene homopolymer containing different flame retardant compositions

It can be concluded from the results reported in Table 3 that the polymer compositions according to the present invention show improved flame retardant properties compared to the referential compositions comprising a single additive at the same loading. By using the inventive compositions, both burning time and damaged length can be significantly reduced. In addition, inventive examples 9 and 10 demonstrate that burning dripping can be prevented by using the inventive flame retardant compositions. Table 4

Test results according to DIN 4102-B2 (flame size: [RXI]20 mm) obtained with 1.0 mm plaques of polypropylene homopolymer containing different flame retardant compositions

The results reported in Table 4 show that the polymer compositions according to the present invention show excellent flame retardancy according to DIN 4102-B2 (1.0 mm). While none of the referential compositions comprising a single additive show significant flame retardant behavior, the inventive combinations of a phosphonate salt and a sterically hindered

N-alkoxyamine provide very efficient flame retardancy. In addition, inventive example 12 demonstrates that burning dripping can be prevented by using a flame retardant composition according to the present invention.

Table 5

UL94 V (1.6 mm) test results from PP block copolymers containing different flame retardant compositions

a ⁾ Number of tests (out of five tests) in which burning drips dripping from the ignited test bar ignite cotton placed underneath the test bar according to the UL94 test norm.

It can be seen from the above mentioned results that the compositions according to the present invention are characterized by their excellent flame retardancy and self-extinguishing properties.