Note: Descriptions are shown in the official language in which they were submitted.
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Title: DRY LARE SYSTEM
The Back round of the Invention
This invention relates to the art of color coating such
edible consumer products as pharmaceutical tablets, confectionary
pieces, and the like. More particularly, the invention is directed
to a dry pigment composition used for making a color coating
suspension. However, the invention also ha~ application to the
internal coloring of products, for example, the internal coloring of
candy.
The color coating of products can be advantageously
accomplished by applying a film forming pigment containing
su~pension, which typically includ~s the presence of a Eil~ forming
polymer. In other cases, the color coating of products is
appropriately accomplished by applying a sugar syrup suspension
containing an aqueous dispersion of pigment.
The yeneral techniques of film coating and sugar coating are
known in the prior art. For example, U.S. Patent No~ 2,954,323 to
Endicott et. al. discloses the improved efficiency of the film
coating process and the superior coating properties of the products
made thereby.
The coating suspensions used in film coating or sugar coating
are typically made from commercially available pigment suspensions,
which are conventionally concentrated non-aqueous dispersions of
lake pigments, usually including a colloid such as
polyvinylpyrollidone for maintaining the pigment in dispersion. The
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pigment dispersions are typically stirred into a larger volume of
polymer solution or sugar solution to form the color coatiny
suspensions. Examples of such pigment dispersions and their use are
described in U.S. Patent No. 3,981,984 to Signorino. The U.S.
application to Heinze et. al., filed on the same day as this
application, discloses an aqueous pigment suspension, including a
viscosity lowering agent such as sodium citrate or similar salts of
carboxylic acids.
The purpose of the present invention was to obtain a dry
composition, rather than a liquid pigment suspension, which could be
added directly to a polymer solution or sugar syrup solution to form
a color coating suspension. Dry compositions have heretofore not
been widely used because of the difficulties involved with their
application. Dry compositions have a tendency to agglomerate and
resist dispersion in solution. This can result in a poor quality
coating, since the coating, in the form of a very thin film, must be
uniform and consistent from one batch of tablets to the next. It is
desired to obtain a coating exhibiting a smooth, polished, and
elegant appearance which requires well dispersed pigment particles.
However, this has been difficult to obtain with a dry composition,
and the results have been unsatisfactory.
U.K. Patent Application GB 2065691A, by Porter et. al.,
published on July 1, l9Ul, discloses a method of making a dry film
coating composition which comprises the steps of mixing a polymer
powder, such as methylcellulose, and pigment particles in a blender,
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adding a placticizer such as polyethylene glycol to the blender
containing the polymer-pigment mix, and mixing until the combined
mix is throughly blended7 A surfactant or a flow aid is optional.
The present applicant has invented a dry composition for uSe
in film coating or su~ar coating, wh;ch comprises pigment particles
and a small quantity of what is referred to as a dispersing agent,
which has an extraordinary effect on the pigment particles. The
dispersing agent effects the pigment particles in the dry state as
well as facilitating dispersion into solution. The dry composition
forms uniform small particles that maintain a striking degree of
separation. The particles do not agglomerate, and as a result, a
more uniform coating i5 obtained. The solubility of the composition
in the film ~orming solution increases by a Eactor of five or more.
The phenomenon known as specking, caused by larger sized pigment
particles that do not disperse, is rendered insignificant or absent.
The present composition need not contain the high levels of
polymer or plasticizer required in U.K. Pa~ent Application
GB 2065671A, referred to above. The present composition is useful
in both aqueous and organic film coating and in sugar coating as
well. The composition readily disperses in liquid as a result of
the dispersing agent.
$he advantage of a dry pigment composition in comparison to a
liquid pigment suspension is great. The dry pigment composition
would have virtually unlimited stability and storage life~ There is
no danger of the pigment particles settling out and hardening, as is
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liable to occur with pigment suspensions. The necessity for
preservatives and the danger of microcontamination is reduced or
avoided. Since the composition weighs considerably less than the
liquid composition, the expense of shipment and the cost of the
product is reduced. The presence of inflammable or deleterious
organic solvents is obviatedO
A primary object of the present invention is to obtain a dry
pigment composition capable of use in a film forming solution or
sugar solution.
Another object of the present invention is to obtain a dry
pigment composition capable of use for the internal coloring of candy
such as jelly beans.
Another object of the present lnvention ig to obtain a dry
pigment composition which readily disperses in solution.
A further object of the present invention is to obtain a dry
pigment composition which does not agglomerate or form clumps or
specks in solution.
A further object of the present invention is to obtain a dry
pigment composition which exhibits relatively small and uniform
particles.
A further object of the present invention is to obtain a dry
pigment composition which forms a coating which is smooth and elegant
in appearance.
A further object of the present invention is to obtain a dry
pigment composition which has high stability and long storage life.
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The above and other objects of the present invention will
become apparent from a reading of the following detailed description
of the invention and the preferred embodiments thereof.
Detailed Description of the Invent~on
The pigment suspension of the present invention compr ises a
mixture of a pigment and a dispersing agent.
The pigments suitable for use in the context of the present
invention include pigment hydroxide lakes, which are dyes combi~ed
with a metal hydrate substratum. A var iety of lakes, including
lakes incorporating a~o, triphenylmethane, fluorescein, and
sulonated indigo dyes, are suitable in the present invention.
Natural lakes ~uch as carm~ne are sultable. FD6C lakes a~e suitable
for application in food, drug, and cosmetic products. D&C lakes
such as D&C Red 27 are suitable for pharmaceutical and cosmetic
application.
Lakes have been developed with a wide range of strengths.
Yor food and confectionary applications, the mid-range dye content
lakes are the most useful. These lakes are manufactured by Crompton
& Xnowles Corporation of Fairlawn, New 3ersey (hereinafter referred
to as `'C&Kn), and Warner-Jenkinson Manufacturing Company of Saint
Louis, Missouri (hereinafter referred to as "W-J"). For example,
the followinq pigments are commercially available from C&K or W-J:
Yellow # 6/40%
Yellow $ 5/36%
Blue ~ 1/11%
Blue ~ 2/39%
Red ~40/40%
Red #27/36%
Red # 3/40%
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~ 50/50 combination of C&K and W-J lakes may bs preferrable.
In general, it has been found that W-J lakes tend to have a higher
tint, but may cause thickening. ~y using a mixture of W-J and C&K
lakeg t both a high tint and non~thickening is more readily obtained.
Of course, developments and changes in the lakes by their
manufacturers may require a reassessment, as would be understood by
those skilled in the art, of the properties of a particular brand in
regard to use in the present invention.
The dispersing agent is most effectively a salt of an organic,
carboxyl containing compound and mixtures thereof with the acid form.
Preferred dispersing agents include salts of compound~ having one to
four aarboxylic group~. Disp~r~ing agents include, but are not
limited to salts of adipic acid, benzoic acid, citric acid, fumaric
acid, succinic acid, maleic acid, lactic acid, tartaric acid,
ascorbic acid, and propionic acid and mixtures with the acid thereof.
Trisodium phosphate has been found to work in some cases as a
dispersing agen , but in general not as well as the above mentioned
organic, carboxylic containing compounds.
In general, the dispersing agents must, at least partly, be
in the salt form. A 50/50 combination of the salt and acid is
suitable. ~or example, sodium citrate, by itsel~, or a mixture of
sodium citrate and citric acid, produces excellent results. It is
surmised that the dispersing agent complexes or is absorbed by the
lake pigment particles. Due to the wide variety of dyes presen~ in
lake piqments, it is further surmised that the metal hydroxide
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substrate of the FD~C lakes may function in the somplexing of the
dispersing agent. The resulting complex is believed to have
electronic properties such that they repell another such complex,
thereby resulting in readily and uniformly dispersed pigment
particles.
The presence of one of the dispersing agents results in a
dramatic change in the properties exhibited by the pigment
composition~ both in the dry form and in solution. The composition
readily disperses in solution and neither agglomerates nor clumps.
The dispersing agent is preferably present in an amount of 0.005 to
5 percent by weight in the mixture. The agent is more preferably
present in an amount of 0.02 to 3.0 percent and most preerably, in
an amount of 0.1 to 1.5 percent. ~n many ca5e5, even a relatively
very small amount of dispersing agent can drastically and favorably
effect the properties of the composition.
The following ~xamples are intended to illustrate the
invention.
Example l
In a blender, the following c~mponents were weiqhed out and
mixed:
Component Wei~ht
Titanium dioxide 3328 49.99 g
Red 40/40 24.99 9
Yellow 6/40 24.99 g
Sodium Citrate 1.50 g
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This composition readily dispersed in a sugar solution
composed of a mixture of water and sucrose in a ratio of 3 to 7.
This dispersion exhibited excellent coating properties.
Example 2
A drawdown is a test used to simulate the coating process. A
few drops of the suspension to be tested are placed in a line across
a glass plate. Then a metal arm which is spaced a fraction of a
millimeter from the glass plate is used to draw the suspension
across the plate so as to produce a thin film. By examining this
thin film, non-uni~ormity or other possible defects in the
suspension can be observed. If the drawdown is clear and uniform,
it i8 expected that the suspension will produce a goocl coating.
In a blender, the following component~ w~re welghed out and
mixed:
Component Weight
Blue 2/39 50 9
Titanium dioxide 3328 50 g
Sodium Citrate 0.5 g
This composition was dispersed in a sugar syrup solution~o
Drawdowns of the dispersion were made to determine the degree of
dispersion and the unformity of the dispersion. The results were
excellent~
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Comparative Example 3
The composition of Example 1 was repeated, except that sodium
citrate was not included. The composition was as follows:
~omponent Weight
Titanium dioxide 3328 50 9
Red 40/40 ~5 g
Yellow 6/40 25 g
The composition of Example 3 was compared to the composition
of Example 1. ~t is noted that the lake5 of Examples 1 and 3 were
obtained from the same lot 90 that the effect of the presence of the
dispersing agent could be more accurately evaluated. The comparison
involved side-by-side drawdowns and microscopic comparison of the
solutions. The composition of Example 1 was found to be
significantly superior to the composition of Example 3 in every
respect. The dry blend with sodium citrate exhibitea uniformly
small particles, whereas the dry blend without sodium citrate
exhibited agglomerates. Moreover, the particles present in the
composition o comparative example were clearly not as uniform and
relatively larger in average diameter.
With respect to dispersing, the effect of the addition of
sodium citrate was also noticeable. The dry blend with sodium
citrate readily dispersed in about 1 to 2 minutes. In contrast7 the
dry blend without sodium citrate required at least ten minutes to
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mix into the solution.
Example 4
The following components were weighed out and blended:
W~i~ht
Titanium dioxide 3328 2() g
YelloW 6/39 20 9
Sodium Citrate 2 g
This composition of the present invention was compared to the
composition of comparative Example 5 below.
Comparative Examp~e 5
The dry blend of the present invention as illustrated by
Example 4 was compared to the use of a dry blend not containing
sodium citrate. The lakes in both examples were taken from the same
~ lot. This comparative example consisted of the ~ollowing:
; Component Wei~ht
Titanium dioxide 20 g
Yellow 6/39 20 g
~ he compositions of Example 4 and Comparative Example 5,
respectively, were added to a 70/30 sugar syrup solution at a weight
concentration of 1.50 percent. Drawdowns and visual microscopic
observation were made of the respeztive dispersions~
It was found that the dispersion made with the composition of
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Example 4 exhibited dispersed particles that were significantly
smaller and finer in size. ~he dry blend without sodium citrate
re~uired at least five times as long to disperse in the sugar syrup
solution.
~omparative Example 6
The followiny components were weighed out and mixed:
~omponent Weight
Titanium dioxide 3328 lS.00 9
Yellow 6/39 15.00 9
Polyvinylpyrollidone l.00 g
Sugar 41.40 9
Distilled water 27.60 g
A quantity of this mixture was added to a 70/30 sugar water
solution. The suspension was mi~ed well for one halE hour using a
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magnetic ~tirrer and heating to 80 C. Drawdown~ and m~e~epop~
observations were made of the mixture.
This dispersion was found to be inferior to the composition
of the present invention exemplified by Example 4 above. In
comparison, the dispersion of Example 4 showed particles of
significantly smaller and finer size.
The composition of the present invention may contain
additional additivesO For example, in order to make the composition
dustless, a non dusting additive such as propylene glycol, glycerine,
or dioctyl sodium sulfosuccinate ~DSS) may be included in an
effective amount of about five percent.
It is to be understood that the foregoing detailed description
and preferred embodiments are merely given by way of illustration,
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and that modifications may be made, within the skill of the art,
without departing from the scope and spirit of the invenl:ion.
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