WO1994014864A1

WO1994014864A1 - Aminoplast anchored antioxidants

Info

Publication number: WO1994014864A1
Application number: PCT/US1993/012622
Authority: WO
Inventors: Jeno G. Szita; Vazken A. Alexanian
Original assignee: Cytec Technology Corp; American Cyanamid Co
Current assignee: Wyeth Holdings LLC; Cytec Technology Corp
Priority date: 1992-12-29
Filing date: 1993-12-28
Publication date: 1994-07-07
Anticipated expiration: 1995-06-29
Also published as: KR960700284A; EP0677070A1; JPH08505887A

Abstract

This invention provides novel aminoplast anchored, hindered phenolic antioxidants which are useful as stabilizers for coatings and polymers such as polyethylene, polypropylene, and the like to extend their useful life. The aminoplast anchored antioxidants have reduced volatility and increased compatibility compared with their unanchored precursors, and may be prepared, for example, by the reaction of hindered phenols with alkoxymethylated aminoplasts.

Description

AMINOPLAST ANCHORED ANTIOXIDANTS

BACKGROUND OF THE INVENTION

This invention relates to the preparation and use of novel aminoplast anchored phenolic antioxidants.

Stabilization of polymers by incorporation of antioxidant stabilizers in polymer films, coatings, fibers, and molded articles to provide protection against the degrading action of light, moisture, and oxygen has been an active area of work in recent years. However, some deficiencies such as volatility and generally poor retention of existing stabilizers within a polymer matrix still remain largely unsolved. For example, attempts to reduce volatility by using higher molecular weight oligomers and polymers have generally resulted in a decreased retention of the stabilizer due to incompatibility. Extractibility and gradual migration of the stabilizer to the surface and eventual loss are still serious problems plaguing the plastics industry.

Limited attempts to increase the molecular weight of the antioxidant without introducing incompatibility by using anchor groups have been made in the past with some success. Among the anchor groups used for supporting stabilizers, triazines have received some attention. U.S. Patent No. 4,284,790 describes an antioxidant system produced by alkylation of N,N',N"- trimethylmelamine with a meta-halomethyl substituted antioxidant. However, the anchored antioxidant described therein does not contain any alkoxymethyl groups, but contains N-methyl groups. In addition, U.S. Patent No. 4,721 ,792 describes a limited number of stabilizer species utilizing acetylenecarbamide (glycoluril) as an anchor group.

It is the object of this invention to provide novel aminoplast anchored antioxidants. It is another object of this invention to provide novel, oxidation stable compositions containing the novel aminoplast anchored antioxidants of the invention. SUMMARY OF THE INVENTION

This invention provides novel aminoplast anchored, hindered phenolic antioxidants represented by the formula:

wherein R¹ is selected from the group consisting of tertiary alkyl of 1 to 20 carbon atoms and tertiary aralkyl of 9 to 20 carbon atoms; and

wherein R², R³, R⁴, and R⁵ are each independently selected from the group consisting of hydrogen, alkyl of 1 to 20 carbon atoms, aralkyl of 7 to 20 carbon atoms, and a methylene bridge attached to A, with the proviso that one of R², R³,

R⁴, or R⁵ is a methylene bridge attached to A; and

wherein A is an m functional aminoplast anchor molecule to which n phenol rings are attached through n methylene bridges; and

wherein m is at least 1 ; and

wherein n is at least 0.01; and

with the proviso that

(1) when A is attached through a methylene bridge at a point ortho- to the point of attachment of the hydroxy group, the aminoplast anchor molecule is selected from the group consisting of:

wherein R⁷ and R⁸ are independently selected from the group consisting of hydrogen, alkyl of 1 to 20 carbon atoms, aryl of 6 to 20 carbon atoms, and aralkyl of 7 to 20 carbon atoms; and

wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms; and

wherein R¹⁰ is selected from the group consisting of alkyl of 1 to 20 carbon atoms, aryl of 6 to 20 carbon atoms, and aralkyl of 7 to 20 carbon atoms; and wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms;

wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms; and provided the (c) is not N-alkyl substituted;

wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms;

wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms;

wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms;

wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms;

(h) oligomeric aminoplast anchor molecules derived from self- or cross- condensation of any of (a) through (g) and mixtures thereof; and

(i) mixtures of any of (a) through (h);

(2) when A is attached through a methylene bridge at a point meta- to the point of attachment of the hydroxy group, the aminoplast anchor molecule is selected from the group consisting of (a), (b), (c), (d), (e), (f), (g), (h) and (i); and (3) when A is attached through a methylene bridge at a point para- to the point of attachment of the hydroxy group, the aminoplast anchor molecule is selected from the group consisting of (b), (c), (d), (e), (f), (g), (h), and mixtures of any of (b) through (h).

These anchored antioxidants are useful as stabilizers for polymers such as polyethylene, polypropylene, and the like to extend their useful life. The anchored antioxidants have reduced volatility and increased compatibility compared with their unanchored precursors.

This invention is also an oxidation-stable composition containing the novel aminoplast-anchored antioxidants of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Aminoplast Anchors

The aminoplast-anchor molecules of this invention are aminoplast crosslinkers commonly used in coatings, moldings, and adhesives. The term "aminoplast" is defined herein as a class of resins prepared by the reaction of an amino group-containing compound and an aldehyde.

The reaction product of amino group-containing compounds and

aldehydes is often reacted further with an alcohol to produce partially or fully alkylated derivatives. These derivatives are included in the "aminoplast" definition given above. The term "aminoplast" as used in the context of this invention comprises monofunctional or polyfunctional amino resins, and may be monomeric or oligomeric. For example, in the preparation of aminoplasts from amino group-containing compounds and aldehydes and subsequent alkylation, dimeric and oligomeric products resulting from self-condensation reaction are often obtained. These oligomeric self-condensation products are included in the "aminoplast" definition given above.

When aminoplast anchors are described herein as being m functional, it is meant that there are m reactive groups on the aminoplast-anchor molecule, each of which can potentially react with an antioxidant stabilizer group to form the aminoplast-anchored antioxidants of this invention. By way of example, the aminoplast anchors of this invention include the groups represented by the formulae (1 )-(17):

wherein R⁷ and R⁸ are independently hydrogen, alkyl or aryl groups of 1 to 20 carbon atoms;

wherein R¹⁰ is an aliphatic or cycloaliphatic alkyl group of 1 to 20 carbon atoms, such as methyl, ethyl, butyl, cyclohexyl and the like; or

R¹⁰ is an aromatic group of 1 to 20 carbon atoms, such as phenyl, tolyl, naphthyl, and the like; or

R¹⁰ is an aralkyl group of 1 to 20 carbon atoms, such as benzyl, cumyl, and the like;

wherein R is an alkylene or an arylene of 1 to 20 carbon atoms;

(10) polyfunctional carbamates;

(11 ) polyfunctional amides;

(12) hydantoins;

(13) dialkoxyethylene ureas;

(14) dihydroxyethylene urea represented by the formula:

(15) homopolymers and copolymers containing carbamate units of the formula:

wherein R is hydrogen or alkyl, and m is at least 1 ;

(16) oligomeric derivatives thereof; and

(17) mixtures of any of (1) through (16).

The aminoplasts may have, as substituents, a hydrogen, an alkyl or an aryl group of 1 to about 20 carbon atoms, or a stabilizer reactive group such as -CH₂OH and -CH₂ OR⁹ wherein R⁹ is an alkyl group of 1 to about 20 carbon atoms or an aminoplast group-containing oligomeric group provided that the total number of stabilizer reactive groups per each aminoplast anchor is at least 1 , and preferably more than 1 , and further provided that melamine-type aminoplasts are not N-alkyl substituted.

The preferred aminoplast anchors of this invention are substantially fully etherified, substantially fully methylolated, substantially monomeric aminoplast crossiinkers commonly used in the coatings industry. They are characterized by having at least 2, and preferably more than 2 stabilizer reactive groups per anchor molecule.

The most preferred aminoplast anchors of the invention are selected from a group consisting of substantially fully etherified, substantially fully methylolated, substantially monomeric glycoluril, melamine, benzoguanamine,

cyclohexanecarboguanamine. urea, and mixtures thereof.

In addition to the substantially fully etherified, substantially monomeric amine-aldehyde aminoplast anchors described above, the non-etherified or partially etherified, substantially fully methylolated or partially methylolated monomeric and oligomeric aminoplasts are also usable in the composition of this invention.

Aminoplast anchors which contain very few alkoxymethyl groups generally have low solubilities due to the high N-H levels, and therefore are less preferred.

The preferred aminoplast anchors are discussed in greater detail below.

Glycoluril Anchors

The most preferred glycoluril anchors of this invention are N-substituted glycolurils represented by the formula:

wherein at least two of the R groups are selected from the group consisting of methoxym ethyl, ethoxymethyl, propoxym ethyl, butoxymethyl, pentoxymethyl, hexoxymethyl, heptoxy methyl, octoxymethyl, nonoxymethyl, decoxymethyl and mixtures thereof, and the remaining R groups are selected from hydrogen, alkyl, hydroxymethyl, and glycoluril group-containing oligomeric moieties.

While it is preferable to have a multiplicity of alkoxymethyl groups per each glycoluril anchor molecule, under ordinary circumstances it is not necessary to obtain, for example, a pure tetra-substituted monomeric aminoplast such as N,N',N",N"'-tetraalkoxymethylglycoluril represented by formula:

wherein R is an alkyl group of 1 to about 20 carbon atoms. The glycoluril anchor may contain monomeric as well as oligomeric components.

The monomeric tetraalkoxyglycolurils themselves are not considered to be resinous materials since they are, as individual entities, non-polymeric

compounds. They are considered, however, to be potential resin-forming compounds when subjected to heat, and particularly when subjected to heat under acidic conditions. As a result of the described resin-forming ability, the substantially monomeric glycoluril aminoplasts of this invention may produce, during the course of the reaction, varying amounts of oligomeric components such as dimers, trimers, and tetramers. The presence of varying amounts of these oligomeric forms is permissible and indeed beneficial, particularly in cases where higher molecular weight and lower volatility products are desired as in the case of most applications in which the products are used as stabilizers against the degrading action of heat and UV light.

An example of a glycoluril anchor of this invention is POWDERLINK® 1174 powder aminoplast resin, a product of Cytec Industries Inc., West Paterson, N.J., and it has the following properties:

Non Volatiles, minimum : 98

(% by weight)

Appearance : White to pale yellow

granulated flakes

Melting Point (°C) : 90-110°C

Average Molecular Weight : 350

Equivalent Weight : 90-125 Another example of a glycoluril anchor usable in this invention is CYMEL®

1170 fully butylated glycoluril resin, a product of Cytec Industries Inc., West Paterson, New Jersey, having the following properties:

Non Volatiles, minimum : 95

(% by weight)

Appearance : Clear liquid

Color, Maximum (Gardner 1963) : 3

Viscosity (Gardner-Holt, 25°C) : X-Z ₂

Molecular Weight, Average : 550

Equivalent Weight : 150-230

Methylol Content : Very low

Urea Anchors

An example of a urea usable in this invention is BEETLE® 80 butylated urea-formaldehyde resin, a product of Cytec Industries Inc., West Paterson, New Jersey, having the following properties: Appearance : lear Liquid

Color, Maximum (Gardner 1963) : 1

Non-Volatiles (Weight %)* : 96 ± 2

Viscosity (Gardner-Holt, 25°C) : X-Z₃

Solvent Tolerance (ASTM D1198-55) : >500

*Foil Method (45°C/45 min.)

Meiamine Anchors

The melamine-based aminoplast anchors are well known in the art and have been used extensively as effective crossiinkers in coatings.

Unlike the tetrafunctional glycolurils, alkoxymethylmelamine functionality can be a maximum of six in a stabilizingly effective range of 1 to 6 stabilizerreactive alkoxymethyl groups per each meiamine molecule. The melaminebased aminoplast anchors of this invention are exclusive of N-alkyl substituted melamines.

Like the glycolurils, alkoxymethyl melamines can contain dimers, trimers, tetramers, and higher oligomers, each given combination of monomers and oligomers being preferred for a given application. For example, the lower viscosity monomer-rich compositions are preferred for solvent-based high solids coatings.

An example of the substantially fully etherified, substantially fully methylated, substantially monomeric melamines usable in this invention is CYMEL® 303 meiamine crosslinking agent, a product of Cytec Industries Inc., West Paterson, New Jersey, and has the following properties:

Non-Volatiles (% by weight)* : 98

Color, Maximum (Gardner 1963) : 1

Viscosity (Gardner-Holt, at 25°C) : X-Z₂

Free Formaldehyde, maximum (Weight : 0.5

%)

Degree of Polymerization (Average) : 1.75

*Foil Method (45°C/45 min.)

Another example is CYMEL® 300 crosslinker, also a product of Cytec Industries Inc, West Paterson, New Jersey, which is the solid version of

CYMEL® 303, with an average degree of polymerization of 1.35.

Another example of a substantially fully etherified, substantially fully methylolated, substantially monomeric meiamine is CYMEL® 1168 aminoplast resin, a product of Cytec Industries Inc., West Paterson, New Jersey. The alkyl group in CYMEL® 1168 consists essentially of a mixture of methyl and isobutyl groups. It has the following properties:

wherein R is methyl or isobutyl.

Non-Volatiles (% by Weight)* : 98

Color, maximum (Gardner 1963) : 1

Free Formaldehyde, maximum (weight : 0.5

%)

Viscosity (Gardner-Holt, at 25°C) : X-Z₂

Equivalent weight : 150-230

*Foil Method (45°C/45 min.) An example of a substantially methylolated, partially etherified,

substantially oligomeric meiamine is CYMEL® 370 crosslinking agent, a product of Cytec Industries Inc., West Paterson, New Jersey. It has the following properties:

Non-Volatiles (% by weight)* : 88 ± 2

Solvent : Isobutanol

Viscosity (Gardner-Holt, at 25°C) : Z₂-Z₄

Color, maximum (Gardner 1963) : 1

Equivalent weight : 225-325

*Foil Method (45°C/45 min.)

Guanamine Anchors

As in melamines, the partially or fully methylolated or etherified alkyl and aryl guanamine aminoplasts, both in their monomeric and oligomeric forms, are usable as anchors in this invention, with the selection depending on the particular application or the properties desired in the product.

Benzoguanamine, cyclohexylcarboguanamine and acetoguanamine aminoplasts are especially preferred as crossiinkers in this invention. The benzoguanamine crossiinkers are represented by the formula:

wherein R is an alkyl group of 1 to about 20 carbon atoms, or a mixture thereof. An example of a benzoguanamine-based crosslinking agent is CYMEL® 1123 resin as described above, wherein R is a mixture of methyl and ethyl groups. The acetoguanamine-based crosslinkers are represented by the formula:

wherein R is an alkyl group of 1 to about 20 carbon atoms, or a mixture thereof.

The cyclohexylcarboguanamine-based crossiinkers are represented by the formula:

It is evident from the above that a person skilled in the art in selecting suitable crossiinkers for a particular application may choose a mixture thereof which imparts a balance of properties desired for that particular application.

Hindered Phenols

The hindered phenol-type antioxidants suitable for use as starting material in the preparation of the aminoplast anchored antioxidants of the invention are represented by the formula:

wherein R¹ is selected from the group consisting of tertiary alkyl of 1 to 20 carbon atoms and tertiary aralkyl of 9 to 20 carbon atoms; and R², R³, R⁴, and R⁵ are each independently selected from the group consisting of hydrogen, alkyl of 1 to 20 carbon atoms, and aralkyl of 7 to 20 carbon atoms.

The preferred hindered phenols are represented by the formulae:

wherein R is an alkyl of 1 to 20 carbon atoms;

Aminoplast Anchored Antioxidants

Broadly, the hindered phenol-type aminoplast anchored antioxidants are represented by the formula:

wherein A is an m functional aminoplast anchor molecule to which n phenol rings are attached through n methylene bridges, said bridges replacing R³, R⁴, or R⁵ groups on said phenol rings, which aminoplast anchor molecule is selected from the group consisting of:

wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms;

wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms; and provided that (c) is not N-alkyl substituted;

wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms;

wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms;

wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms;

wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms; (h) oligomeric aminoplast anchor molecules derived from self- or cross- condensation of any of (a) through (g) and mixtures thereof; and (i) mixtures of any of (a) through (h);

wherein m is at least 1; and

wherein n is at least 0.01; and

wherein R², R³, R⁴, and R⁵ are each independently selected from the group consisting of hydrogen, alkyl of 1 to 20 carbon atoms, and aralkyl of 7 to 20 carbon atoms. The aminoplast anchored antioxidants of the invention are prepared by contacting a hindered phenol with an alkoxymethylated or hydroxymethylated amino resin such as those referred to herein as aminoplasts. The contacting is carried out in the presence of an acid catalyst to accelerate the formation of the anchored antioxidants. The acid catalyst is typically a sulfonic acid, however any acid known to catalyze the reactions of aminoplasts may be used.

Para Bridged Antioxidants

The hindered phenol-type aminoplast anchored antioxidants wherein the methylene bridges are attached at a point para- to the point to attachment of the hydroxy group may be represented by the formula:

wherein R²⁷ and R²⁸ are the same or different and are independently selected from the group consisting of methyl, ethyl, 1-propyl, 2-propyl, 1 -butyl, 2-butyl, 1-pentyl, 2-pentyl, 3-pentyl, and neopentyl groups; and

wherein A is an m functional aminoplast anchor molecule-to which n phenol rings are attached through n methylene bridges, which aminoplast anchor molecule is selected from the group consisting of:

wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms;

wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms;

wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms;

wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms;

wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms;

(i) mixtures of any of (a) through (h);

wherein m is at least 1 ; and wherein n is at least 0.01.

The preferred para- bridged hindered phenol-type antioxidants are those represented by the formula:

wherein A is an m functional aminoplast anchor molecule to which n phenol rings are attached through n methylene bridges at a point of attachment para- to the point of attachment of the hydroxy group, which aminoplast anchor molecule is selected from the group consisting of:

wherein R⁹ is selected from the group consisting of methyl, ethyl, 1-propyl, 2-propyl, 1 -butyl, 2-butyl, and mixtures thereof;

wherein R⁹ is selected from the group consisting of methyl, ethyl, 1-propyl, 2-propyl, 1 -butyl, 2-butyl, and mixtures thereof; and provided that (b) is not N-alkyl substituted;

wherein R⁹ is selected from the group consisting of methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl, and mixtures thereof;

(d) oligomeric aminoplast anchor molecules derived from self- or cross- condensation of (a), (b), (c), or mixtures thereof; and

(e) mixtures of any of (a) through (d);

wherein m is at least 1 ; and where n is at least 0.01.

The preferred aminoplast anchor molecules are selected from the group consisting of:

(e) mixtures of any of (a) through (d);

provided (b) is not N-alkyl substituted.

An example of a preferred embodiment of the hindered phenol-type aminoplast anchored stabilizers wherein the methylene bridges are attached at a point para- to the point of attachment of the hydroxy group is represented by the formula:

wherein A is a glycoluril anchor, and

wherein m is 2 to 14, and

wherein n is in the range of 1 to about 14, and

wherein the ratio of the hindered phenol to glycoluril is from about 1 :1 to about

4:1 , and

wherein the glycoluril is a mixture of monomeric, dimeric, trimeric, tetrameric, and higher oligomeric units.

Meta Bridged Antioxidants

The hindered phenol-type aminoplast anchored antioxidants wherein the methylene bridges are attached at a point meta- to the point of attachment of the hydroxy group and ortho- to R²⁹ may be represented by the formula:

wherein A is an m functional aminoplast anchor molecule to which n phenol rings are attached through n methylene bridges at a point of attachment meta- to the point of attachment of the hydroxy group, which aminoplast is selected from the group consisting of:

wherein R⁷ and R⁸ are independently selected from the group consisting of hydrogen, alkyl of 1 to 20 carbon atoms, aryl of 6 to 20 carbon atoms, and aralkyl of 7 to 20 carbon atoms; and wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms;

wherein R⁹ is selected from the group consisting of alkyl of 1 to 20 carbon atoms, aryl of 6 to 20 carbon atoms, and aralkyl of 7 to 20 carbon atoms; and wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms;

wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms;

wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms;

wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms;

wherein m is at least 1 ; and wherein n is at least 0.5; and

wherein R²⁷ is selected from the group consisting of methyl, ethyl, 1 -propyl, 2- propyl, 1 -butyl, 2-butyl, 1-pentyl, 2-pentyl, 3-pentyl, and neopentyl groups; and wherein R²⁹ is an alkyl of 1 to 20 carbon atoms.

The preferred hindered phenol-type antioxidants bridged meta- to the hydroxy group are represented by the formula:

wherein A is an m functional aminoplast anchor molecule to which n phenol rings are attached through n methylene bridges at a point of attachment meta- to the point of attachment of the hydroxy group, which aminoplast anchor molecule is selected from the group consisting of:

(e) mixtures of any of (a) through (d);

wherein m is at least 1; and wherein n is at least 0.01.

(e) mixtures of any of (a) through (d);

provided (b) is not N-alkyl substituted.

An example of a preferred embodiment of the hindered phenol-type aminoplast anchored antioxidants wherein the methylene bridges are attached at a point meta- to the point of attachment of the hydroxy group is represented by the formula:

wherein A is a glycoluril anchor; and

wherein m is 2 to 14; and

wherein n is in the range of 1 to about 14; and

4:1; and

Ortho Bridged Hindered Phenol Stabilizers

The hindered phenol-type aminoplast anchored antioxidant wherein the methylene bridges are attached at a point ortho- to the point of attachment of the hydroxy group may be represented by the formula:

wherein A is an m functional aminoplast anchor molecule to which n phenol rings are attached through n methylene bridges at a point of attachment ortho- to the point of attachment of the hydroxy group, which aminoplast is selected from the group consisting of:

wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms;

wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms;

wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms;

wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms;

wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms;

(i) mixtures of any of (a) through (h);

wherein m is at least 1 ; and

wherein n is at least 0.5; and

wherein R²⁷ is selected from the group consisting of methyl, ethyl, 1-propyl, 2- propyl, 1 -butyl, 2-butyl, 1-pentyl, 2-pentyl, 3-pentyl, and neopentyl groups; and wherein R²⁹ is an alkyl of 1 to 20 carbon atoms.

An example of the ortho-bridged anchored antioxidants is represented by the formula:

wherein A is an m functional aminoplast anchor molecule to which n phenol rings are attached through n methylene bridges at a point of attachment ortho- to the point of attachment of the hydroxy group, which aminoplast anchor molecule is selected from the group consisting of:

(e) mixture of any of (a) through (d);

wherein m is at least 1; and wherein n is at least 0.01.

Another example of the ortho- bridged hindered phenol-type aminoplast anchored antioxidants is represented by formula:

wherein A is a glycoluril anchor; and

wherein m is in the range of from 2 to 14; and

wherein n is in the range of from about 1 to 14; and

wherein the ratio of hindered phenol to glycoluril is 3.7:1; and

wherein the glycoluril anchor is a mixture of monomeric, dimeric, trimeric, tetrameric, and higher oligomeric units having an average methoxymethyl to glycoluril ratio of 0.1:1.

Utility of Aminoplast Anchored Antioxidants

The anchored antioxidants of the invention are used as additives to stabilize thermoset or thermoplastic polymers against the degrading action of oxygen, heat, and light. They may be chemically bound to the polymer (reactive antioxidants) or they may be used as an additive to the polymer (non-reactive antioxidant).

The aminoplast-anchored antioxidants of the invention may participate in the crosslinking process as crosslinking agents if they possess at least two alkoxymethyl groups. If the antioxidant has only one alkoxymethyl group present, it may still react non-crosslinkingly with an alkoxym ethyl-reactive group present in a curable composition and thereby become part of the cured or crosslinked polymer.

In both of the above situations, the aminoplast-anchored antioxidants of the invention function as "reactive" antioxidants.

In situations wherein the antioxidant contains little or no alkoxymethyl groups, the antioxidant cannot participate in the reaction which could bind the antioxidant to the polymer. In this case, it is merely an additive to the polymeric material and functions as a "non-reactive" antioxidant. Oxidation-Stable Compositions

This invention is also an oxidation-stable composition comprising:

(i) a polymeric material, and

(ii) an aminoplast-anchored antioxidant.

The aminoplast-anchored antioxidants (ii) usable in the oxidation stable compositions are the novel aminoplast-anchored antioxidants of the invention described hereinabove in the section entitled "AMINOPLAST ANCHORED ANTIOXIDANTS."

The polymeric materials usable in the oxidation-stable composition are the polymers generally referred to as thermoset or thermoplastic polymers.

A. Thermoset Systems

The thermoset systems include amino resins, urethanes, epoxies, phenolplasts, and any reactive, curable system capable of forming a polymeric crosslinked material upon curing. In this case, the anchored antioxidant (ii) is typically added to the curable composition prior to curing the thermoset systems to ensure uniform distribution of the additive in the crosslinked polymer.

B. Thermoplastic Systems

The thermoplastic systems include polyolefins such as polyethylene, polypropylene, polystyrene, polyacrylates, polyvinyl chloride, polyvinyl acetate or condensation polymers such as polycarbonates, polyesters, polyamides, polysulfones and the like. The thermoplastic polymeric material (i) may be a mixture of at least two polymers or it may be a polymer derived from the copolymerization of at least two monomers.

The polypropylene resins may be any of the commercially produced polypropylenes, inducing impact-improved polypropylene polymers, polypropylene blends, and ethylene-containing polypropylene copolymers. They may be produced by polymerization of propylene or propylene-ethylene mixtures by contacting the monomers with Ziegler-Natta coordination catalysts, specifically those in which the transition metal is titanium, according to well known and widely practiced methods. In the case of thermoplastic systems, the anchored antioxidant (ii) is typically blended with solid polymeric material with or without other stabilizers, and the admixture thereafter is melted to obtain uniform oxidation-stable compositions. The optional stabilizers include UV absorbers, hindered amine light stabilizers, phosphites, sulfides and the like.

The concentration of the anchored antioxidant in the oxidation-stable compositions is in the range of from about 0.01 weight percent to about 5 weight percent, with 0.1 to 1.2 weight percent range being preferred. Example 1

A mixture of POWDERLINK® 1174 resin (31.8g) and 2,6-di-tertiarybutyl phenol (82.4g) was melted at about 60°C. Para-toluenesulfonic acid

monohydrate (1.0g) was added to the melt at 60°C and the temperature of the reaction mixture was raised to 110°C (10 min) and the methanol formed was removed by distillation. The temperature of the mixture gradually rose to 120°C (90 min). The bottoms product was then poured on an aluminum tray and heated at about 100°C under reduced pressure in a vacuum oven for an additional 30 min. On cooling, an amber colored, brittle solid was obtained which was soluble in tetrahydrofuran, acetone, lower alcohols, and chloroform, but was insoluble in water or aliphatic hydrocarbons such as heptane.

The product was purified by dissolving in acetone and pouring the acetone solution into heptane. The product was the para- bridged adduct of 2,6-di- tertiarybutyl phenol with POWDERLINK® 1 174 resin. ¹H Nuclear Magnetic Resonance Spectroscopy (NMR) indicated replacement of the methoxy groups of the POWDERLINK® 1174 by the 2,6-di-tert-butyl phenol at the para- position forming a methylene bridge. ¹³C NMR indicated a phenol to glycoluril molar ratio of 1.5:1. Example 2

The procedure of Example 1 was repeated using 2-tertiary-butyl-4-methyl phenol instead of the 2,6-di-tertiary-butyl phenol. The product was the ortho- bridged adduct having a hindered phenol to glycoluril ratio of 3.7:1 and methoxymethyl to glycoluril ratio of 0.1 :1. The Number Average Molecular Weight (Mn) of the product was about 2,300. Example 3

The following formulations were prepared:

(A) Formulation A (Control):

Three polypropylene films were prepared as follows:

PROFAX® 6501 Polypropylene Resin was milled at 165-175°C and then it was compression molded into an 18-20 mil (0.46-0.51 mm) film at 210°C to give the Control Film.

(B) Formulation B:

A set of three additional films were prepared as follows:

The procedure in (A) was repeated with a 0.2 weight percent of the anchored antioxidant of Example 1 being added to the polypropylene in the milling step to give Stabilized Film (1 ).

(C) Formulation C:

Procedure in (B) was repeated with 0.2 weight percent of the anchored antioxidant of Example 2.

Formulations A, B, and C were tested by exposing three films of each formulation to air at 140°C in a Forced Air Oven until degradation occurred. Formulation A, with no antioxidant additive, served as the control. The test results are summarized in Table 1.

It is concluded from the results in Table 1 that films containing the anchored antioxidants of the invention (Formulations B and C) are effective antioxidants for polypropylene, with the antioxidant having the higher hindered phenol content being the more active. TABLE 1

ANTIOXIDANT ACTIVITY OF

POWDERLINK® 1174 RESIN-ANCHORED HINDERED

PHENOL ANTIOXIDANTS IN POLYPROPYLENE

* Exposure to air at 140°C in a Forced Air Oven.

** 2,4-di-tert-Butylphenol/POWDERLINK® 1174 (1.5:1 Ratio).

*** 2-tert-Butyl-4-methylphenol/POWDERLINK® 1174 (3.7:1 Ratio).

One possible method of producing meta-bridged hindered phenol stabilizers would be to use an ortho-, para-blocked hindered phenol, such as 2,6 d.-tertiary-butyl-4-methyl phenol, as the hindered phenolic starting material in the above-described examples. It is well known to those skilled in the art that phenolic electrophilic substitution is favored on the aromatic ring at those positions ortho and para to the hydroxy group. By blocking the favored ortho and para positions, it should be possible to produce the meta-bridged hindered phenol stabilizers of this invention. It is expected that the meta-bridged stabilizers would be at least as effective as the ortho- and para- bridged stabilizers as anchored antioxidants.

Although the present invention has been described with reference to certain preferred embodiments, it is apparent that modifications and variations thereof may be made by those skilled in the art without departing from the scope of the invention as defined by the appended claims.

Claims

WHAT IS CLAIMED:

1. A composition of matter represented by the formula:

R⁴, or R⁵ is a methylene bridge attached to A; and

wherein m is at least 1 ; and

wherein n is at least 0.01 ;

with the proviso that

(1 ) when A is attached through a methylene bridge at a point ortho- to the point of attachment of the hydroxy group, the aminoplast anchor molecule is selected from the group consisting of:

wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms; and

wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms;

wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms;

wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms;

wherein R⁹ is a linear or branched alkyl group of 1 to 20 carbon atoms;

(i) mixtures of any of (a) through (h);

2. The composition of matter of claim 1 , wherein A is attached through a methylene bridge at a point ortho- to the point of attachment of the hydroxy group.

3. The composition of matter of claim 1 , wherein A is attached through a methylene bridge at a point meta- to the point of attachment of the hydroxy group.

4. The composition of matter of claim 1 , wherein A is attached through a methylene bridge at a point para- to the point of attachment of the hydroxy group.

5. The composition of matter of claim 2 represented by the formula:

6. The composition of matter of claim 3 represented by the formula:

7. The composition of matter of claim 4 represented by the formula:

wherein R²⁷ and R²⁸ are the same or different and are independently selected from the group consisting of methyl, ethyl, 1-propyl, 2-propyl, 1 -butyl, 2-butyl, 1- pentyl, 2-pentyl, 3-pentyl, and neopentyl groups.

8. An oxidation-stable composition comprising:

(i) a polymeric material, and

(ii) an aminoplast-anchored antioxidant as recited in any one of claims 1-7.

9. The oxidation-stable composition of claim 8 wherein the polymeric material (i) is a thermoset resin selected from the group consisting of aminoresins, urethanes, epoxies, phenolplasts, and mixtures thereof.

10. The oxidation-stable composition of claim 8 wherein the polymeric material (i) is a thermoplastic resin selected from the group consisting of polyethylene, polypropylene, polystyrene, polyacrylates, polyvinyl chloride, polyvinyl acetate, polycarbonate, polysulfone, and mixtures thereof.

11. The oxidation-stable composition of claim 10 wherein the polymeric material (i) is polypropylene.

12. The oxidation-stable composition of claim 8 wherein the concentration of the aminoplast-anchored antioxidant in said composition is from 0.01 to 5 weight percent.