Colored wax articles

Details Colored wax articles Colored wax articles

1998-10-12

2001-07-17

Cain, Edward J. (Department: 1714)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Processes of preparing a desired or intentional composition...

C524S100000, C524S104000

Reexamination Certificate

active

06262153

ABSTRACT:

FIELD OF THE INVENTION
The field pertains to shaped wax-based articles such as crayons, paper coatings, food packaging, candles, and the like.
BACKGROUND OF THE INVENTION
The term “wax”, used herein is defined in accordance with the German Society of Fat Science as:
(1) at 20° C. it forms a solid whose consistency goes from kneadable to brittle;
(2) having a macro- to -micro-crystalline structure;
(3) melting at temperatures of 40° C. and above;
(4) a relatively low viscosity at temperatures slightly above its melting point;
(5) consistency and solubility that are strongly dependent upon temperature; and
(6) that which can be polished under slight pressure.
Among the various types of natural waxes are insect and animal waxes such as beeswax, lanolin, shellac wax, chinese insect wax, and spermaceti; vegetable waxes such as camauba, candelila, japan wax, ouricury wax, rice-bran wax, jojoba wax, castor wax, bayberry wax, sugar cane wax, and maize wax; mineral waxes such as montan wax, peat wax, petroleum waxes including petrolatum, paraffin wax, semimicrocrystalline wax, and microcrystalline wax, ozokerite and ceresin waxes; and the synthetic waxes such as polyethylene wax, Fischer-Tropsch wax, chlorinated naphthalene wax, chemically modified wax, substituted amide wax, ester waxes, hydrogenated vegetable fats and derivatives, alpha olefins and polymerized alpha olefin wax.
Waxes are used in a variety of applications including, but not limited to, polishes, candles, crayons, fertilizer coatings, rosebush coatings, plant grafting, sealants, sun-cracking protection of rubber and plastic products, paper coating, packaging food products, electrical insulation, waterproofing and cleaning compounds, carbon paper, and precision investment casting.
Some polymers of higher alpha olefins, for example C
<20
, are waxes and are sold as synthetic waxes. The polymerization process yields highly branched materials, typically with broad molecular weight distributions. Properties of the individual products are highly dependent on the alpha olefin monomers and polymerization conditions. The molecular structure of poly(&agr;-olefins) is sometimes used to modify the properties of paraffin wax, primarily for improving shape retention in unsupported, molded or dipped articles, such as candles. The products can increase the hardness and opacity of the paraffin, without increasing the cloud point or viscosity.
U.S. Pat. No. 4,060,569 relates to hydrocarbon polymers having lower penetration or greater hardness, greater viscosities, higher molecular weights, but having melting points and congealing points which are essentially no higher, but preferably lower than the original hydrocarbon. U.S. Pat. No. 4,239,546 relates to the use of hydrocarbon polymers to improve the hardness of waxes. In both patents, the hydrocarbons employed are primarily alpha olefins of the formula RCH=CH
2
, but also include alpha olefins of the vinylidene structure
or a mixture of alpha olefins, vinylidenes, internal olefins and saturates.
An application of particular commercial importance is the colored, molded wax candle. Over the years, there has been an increasing desire in the marketplace and a need by candle manufacturers for a colored candle that does not fade when exposed to fluorescent light or ultraviolet (UV) light. UV light is known to break chemical bonds in colorants and waxes, resulting in loss of original properties. Colorants, such as dyes and pigments, can fail due to strong UV light absorption resulting in rapid color fading. An organic mixture or compound, such as a colorant or wax, can also degrade through free radical attack. UV absorber can be used to dissipate the absorbed energy as heat. Commercial UV absorbers used for UV stabilization of waxes are the hydroxy substituted benzophenones and benzotriazoles. These compounds differ in cost, solubility, volatility, and their absorptivity at specific wavelengths .
The use of UV absorbers in cosmetic compositions for human skin and hair applications is known. U.S. Pat. No. 5,508,025 discloses UV absorbers and cosmetic compositions containing a naphthalene methylenemalonic diester.
The use of UV absorbers in plastics and coatings to enhance weather resistance is known. U.S. Pat. No. 4,301,209 discloses a radiation curable coating composition comprising a benzylidene malonic acid ester UV light absorber of the formula
wherein R
4
is independently alkyl or hydroxyalkylene.
It is known from U.S. Pat. Nos. 4,260,732 and 4,404,257 to stabilize polycarbonate resins for improved resistance to UV radiation with UV absorber (UVA) compounds including the benzophenone derivatives, benzotriazole derivatives, benzoate esters, phenyl salicylates, derivatives of crotonic acid, malonic acid esters, and cyanoacrylates. U.S. Pat. No. 5,439,958 discloses piperidine compounds which can be used as light stabilizers, heat stabilizers, and oxidation stabilizers for organic materials, in particular synthetic polymers.
Thermal degradation is a concern primarily during manufacturing processes where a wax is held for extended lengths of time at or above the melt temperature. Antioxidants are often added to the melted wax to inhibit degradation during manufacturing. The melting point of thermally degraded candle wax is lower than the original wax material. The thermally degraded material also becomes more UV light sensitive and accelerates the photodegradation of dyes.
The problem of rapid color fading is manifested in finished candles which are displayed at the point of purchase under exposure to sunlight and/or fluorescent light. Even fluorescent light (wavelength from 290 to 380 nm) causes colored candles to fade noticeably in a short period of time. Premature color fading is therefore problematic for decorative wax articles and there is a continuing need for longer shelf-life yet there is no basis for predicting improved stabilizing effects in relatively low molecular weight, nonpolar waxes based on observations of effects seen among the stabilizers used for high polymers which are polar in nature. A surprising improvement in the color retention and shelf life of wax-based articles has been observed with a particular UV absorber. The UV absorbing additives which show the improvement exhibit a UV absorptivity greater than or equal to 40 liters per gram-cm. at a wavelength of less than or equal to 400 nm, as measured in either methanol, toluene or chloroform, using a UV spectrophotometer.
SUMMARY OF THE INVENTION
It is an object of the present invention to produce an improved solid, colored, molded wax-based article having surprisingly longer color shelf-life. The invention comprises a synthetic wax, a colorant, and an effective amount of a compound of the formula (1)
wherein
R
1
is independently C
1-20
alkyl, C
1-20
alkoxyalkyl, C
1-20
hydroxyalkyl, C
1-20
alkenyl, substituted C
1-20
alkenyl groups, C
1-20
-alkoxy-C
1-20
-alkyl groups, C
1-20
-oxy-N-C
1-20
-alkyl groups, —N-cyclic-C
1-10
-alkyl groups, and cyclic-N-C
1-10
-alkyl groups;
R
11
, is hydrogen or C
1
-C
8
alkyl;
p and q are independently 0 or 1;
Ar is a substituted or unsubstituted aromatic single ring or a substituted or unsubstituted aromatic fused 2 or 3 ring group or a heteroaromatic single ring or a heteroaromatic fused 2 or 3 ring group, for example a substituted or unsubstituted phenyl or naphthyl group;
R
3
is hydrogen, C
1
-C
18
alkyl, C
5
-C
12
cycloalkyl unsubstituted or mono-, di- or tri- substituted by C
1
-C
4
alkyl, or C
7
-C
9
phenylalkyl unsubstituted or mono-, di- or tri- substituted on the phenyl by C
1
-C
4
alkyl, or preferably a hindered amino group selected from (i) to (xi):
wherein
R, R′ and R
5
are independently either hydrogen, C
1-12
alkyl, C
1-8
alkoxy, or —COR
3′
, where R
3′
is hydrogen, C
1-6
alkyl, phenyl, —COO(C
1-4
alkyl) or NR
15
R
16
, where R
15
and R
16
are independently hydrogen, C
1-12
alkyl, C
5-6
cycloalkyl, phenyl or (C
1-12
alkyl)phenyl; or R
15
and R
16
together with the N-atom to which they are attached form a five- to seven-membere

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