Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1994-06-01
2002-09-17
Sanders, Kriellion A. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S120000, C524S126000, C524S195000, C252S400240, C252S403000
Reexamination Certificate
active
06451888
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to solid phosphate stabilizer compositions, and more particularly relates to solid phosphite stabilizer compositions exhibiting enhanced hydrolytic stability.
2. Description of the Related Art
Hydroxyphenyl alkyleneyl isocyanurates have been utilized in conjunction with the phosphites, specifically pentaerythritol phosphites, for the stabilization of polyolefins, see Gilles, U.S. Pat. No. 4,025,486, issued May 24, 1977. The Gilles reference while teaching enhanced stability for the polyolefin materials by utilizing in combination isocyanurate compounds and phosphite compounds therein, in respective amounts of 0.01 part to 5 parts by weight of hydroxyphenylalkyleneyl isocyanurate compound per 100 parts by weight of organic material, and the pentaerythritol phosphite at 0.01 part to 5 parts by weight per 100 parts by weight of organic material. In other words, while Gilles, U.S. Pat. No. 4,025,486, addresses the stability issues associated with polyolefin compositions, Gilles neither shows nor suggests how to address the hydrolysis problems associated with the phosphite by preparing a stabilizer composition containing relatively large amounts of the phosphite and the hindered phenolic isocyanurate.
The susceptibility of organic phosphites to hydrolysis, is known. Prior attempts to enhance the hydrolysis resistance of various phosphites by utilizing a continuous phase of amorphous tetrakis-(3-(3,5-di-tert-butyl-4-hydroxyphenol)-propionyloxymethyl) methane as set out in Neri et al., U.S. Pat. No. 4,957,956, issued Sep. 18, 1990, which is incorporated herein by reference, have exhibited some enhancement in hydrolytic stability, but generally blends of such material can experience hydrolytic instability after extended exposure to humidity at ambient temperature. Additionally, there is a desire to provide hindered phenolic/phosphite blends which optionally can utilize a phosphite having a melting point either within or outside of the melting point specified in Neri et al., U.S. Pat. No. 4,957,956.
SUMMARY OF THE INVENTION
The present invention involves a solid phosphite stabilizer composition with improved hydrolytic stability, which comprises a melt blend of an organic phosphite and a hindered phenolic isocyanurate, more preferably comprises a blend of a phosphite and tris(3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate. The blends have surprisingly and unexpectedly exhibited superior hydrolytic stability compared to melt blend compositions comprising phosphite and tetrakis(3-(3,5-di-tert-butyl-4-hydroxy phenol)-propionyloxymethyl) methane. The solid stabilizer compositions are useful as additives for stabilizing polymeric compositions.
DETAILED DESCRIPTION OF THE INVENTION
The hydroxyphenylalkyleneyl isocyanurate compounds have the formula
wherein R
4
is a hydroxyphenylalkyleneyl radical of the formula
where m is 1 to 4, r
1
is an alkyl radical having 1 to 18 carbon atoms and is positioned immediately adjacent to the hydroxy group on the ring; r
2
, r
3
and r
4
are hydrogen or an alkyl radical containing 1 to 18 carbon atoms, and R
5
and R
6
are hydrogen, an alkyl radical containing 1 to 18 carbon atoms, or are the same as R
4
. A more preferred compound is when R
5
and R
6
are equal to R
4
, i.e., all the R
4
, R
5
and R
6
groups are hydroxyphenylalkyleneyl radicals, and r
1
is a t-alkyl radical containing from 4 to about 12 carbon atoms, r
2
is an alkyl radical containing 1 to about 12 carbon atoms, r
3
and r
4
are hydrogen, and m=1.
Even more preferred are the symmetrical tris(3,5-di-tert-alkyl-4-hydroxybenzyl) isocyanurates of the formula
where n is 4 to 8.
Examples of the 4-hydroxybenzyl isocyanurate compounds are: tris-(3-methyl-4-hydroxybenzyl)isocyanurate, tris-(3-t-butyl-4-hydroxybenzyl)isocyanurate, tris-(3-t-amyl-4-hydroxybenzyl)isocyanurate, tris-(3-cetyl-4-hydroxybenzyl)-isocyanurate, tris-(3,5-dimethyl-4-hydroxybenzyl)isocyanurate, tris-(3,diisopropyl-4-hydroxybenzyl)isocyanurate, tris-(3-methyl-5-isopropyl-4-hydroxybenzyl)isocyanurate, tris-(3-hexyl-4-hydroxybenzyl)isocyanurate, tris-(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate, tris-(3-t-butyl-5-t-amyl-4-hydroxy-benzyl)isocyanurate, tris-(3,5-di-t-amyl-4-hydroxybenzyl)-isocyanurate, tris-(3,5-di-(1-methyl-1-ethylpropyl)-4-hydroxy-benzyl)isocyanurate, tris-(3,5-di-(1,1,2,2-tetramethylpropyl)-4-hydroxybenzyl) isocyanurate, tris-(3,5-di-(1-di-methylpentyl)-4-hydroxybenzyl)-isocyanurate, bis-(3-methyl-4-hydroxybenzyl)-isocyanurate, bis-(3-t-butyl-4-hydroxybenzyl)isocyanurate, bis-(3,5-dimethyl-4-hydroxybenzyl)isocyanurate, bis-(3,5-di-t-butyl-4-hydroxybenzyl)-isocyanurate, (3-methyl-4-hydroxy-benzyl)isocyanurate (3-t-butyl-4-hydroxybenzyl)isocyanurate, (3,5-dimethyl-4-hydroxbenzyl)isocyanurate, (3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate, and the like. Reference is made to U.S. Pat. No. 3,531,483 which discloses isocyanurate compounds encompassed by this invention. The patent shows the preparation of these compounds and their utility as stabilizers, and is hereby incorporated by reference. By utilizing a high melting temperature hydroxyphenyl alkyleneyl isocyanurate, suitable solid particles may be obtained even when a viscous liquid phosphite is used as the organic phosphite of the present compositions. In other words, phosphites (such as itrisnonylphenyl phosphite) having melting temperatures below 25° may be successfully utilized in the compositions of the present invention to provide free flowing solid particles at room temperature.
Considerable phosphites include those elected from the general formula
wherein R
1
, R
2
and R
3
represent either equal or different hydrocarbyl radicals, which can be either alkyl, cycloalkyl, aryl, alkaryl or aralkyl radicals; an either amorphous or crystalline organic phosphite, in the form of particles with a particle size comprised within the range of from 30/&mgr;m to 2 mm, with said organic phosphite having a melting point higher than approximately 100° C., and being selected from those definable by the general formulae:
wherein the R
7
and R
8
radicals independently represent either alkyl, cycloalkyl, aryl, alkaryl or aralkyl radicals.
The phosphite is preferably a pentaerythritol phosphite which may be selected from the group consisting of (a) compounds of the formula
wherein R
7
is an aliphatic radical containing 1 to about 20 carbon atoms, a cycloalkyl ring of 5 to about 8 carbon atoms, or an aryl, alkaryl, or aralkyl group of 6 to about 14 carbon atoms, and (b) compounds of the formula
wherein R
7
is defined as above. Illustrative of these compounds are those where when R
7
is an aliphatic radical; R
7
can be (a) an alkyl radical such as methyl, ethyl, isopropyl, n-butyl, n-boxyl, 2-ethylhexyl, n-dodecyl, n-tetradecyl, n-octadecyl, and the like, (b) an alkoxyalkyl radical of 2 to about 20 carbon atoms such as methoxyethyl, ethoxyethyl, ethoxypropyl, and the like, and (c) alkoxy carboalkyl radicals of 2 to about 20 carbon atoms such as methoxycarboethyl, propyloxycarboethyl, decyloxycarboethyl, and the like. When R
7
is a cycloalkyl ring, illustrations of R
7
include cyclopentyl, cyclohexyl, cyclooctyl, and the like. When R
7
is an aryl group, phenyl and naphthyl are examples thereof. The aryl group can be halogenated as in a bromophenyl group. Lastly, when R
7
is alkaryl of 7 to about 14 carbon atoms; i.e., an alkyl-substituted phenyl or naphthyl group, illustrations thereof are methylphenyl, t-butyl-phenyl, nonylphenyl, and the like; and when R
7
is aralkyl of 7 to about 14 carbon atoms; i.e., an aryl-substituted alkyl group, benzyl and phenylethyl are examples thereof. The alkaryl or aralkyl group can be halogenated as in a 2-chloroethylphenyl group.
Examples of the defined pentaerythritol phosphites are dimethylpentaerythritol diphosphite, diethylpentaerythritol diphosphite, didodecylpentaerylthritol diphosphite, dioctadecylpentaerythritol diphosphite, diphenylpentaerylthritol diphosphite, ditolylpentaerythritol diphosphite, di-p-chlorophenylpentae
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