DE2031675A1 - Colored, finely divided resins and their use in toothpaste - Google Patents

Description

The Procter & Gamble Company Cincinnati, Ohio, V.St.A.

Colored, finely divided resins and their use in toothpaste

The invention relates to a process for the production of frozen resins using non-toxic, water-soluble resins dyes. This process produces color-fast particles made of largely water-impermeable, cross-linked ^ thermosetting Resin containing water-soluble dyes suitable for use in foods, drugs and cosmetics are approved or are considered safe for use in products that are absorbed by the human body can. The process according to the invention is characterized in that the polymerization required to obtain the resins is carried out in aqueous solution and a non-toxic, water-soluble dye dissolved in the aqueous solution dissolves before the polymerization is complete.

J) The colored narcotic particles obtained can be used for this purpose To be able to give toothpastes an attractive and eye-catching appearance and in some cases to increase the cleaning and polishing effect of the toothpaste. It has long been recognized that

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Faroe plays a major role in the assessment of a product by the consumer. In many cases, color has the task of defining certain things To distinguish products from others and to specialize in them To point out the properties of our products are usually obtained by adding the desired color to the other ingredients before mixing will. Because all the dyes currently used in toothpastes are water-soluble and large amounts of water are contained in the toothpastes, which distribute the color and colors the entire product evenly. Another option for evenly coloring a toothpaste which aucxi in the Rah-P What falls within the scope of the present invention consists in the presence of very small particles of insoluble, colored material in the pasta act as a pigment to distribute evenly, although such a material under the magnifying glass as discrete, colored ! Particles can be recognized, has the Pabta for the naked eye a uniformly colored appearance. The prerequisite is of course lich that the Parcikem, which serve as pigments, with a dye are colored that are safe for products intended for human consumption

It is true that the complete coloration of a product can be for the consumer very attractive, but will be much larger Effects achieved with speckled products in which a a lesser amount of particles so large that they are in a composition of a different color are easy to see with the naked eye. When relatively large colored particles are evenly distributed, it becomes a product preserved, the numerous discrete, well-defined centers of contrasting color randomly but evenly distributed and has a striking and highly distinguishable appearance.

Granular detergent compositions prepared by means of colored particles are speckled have been known for a long time. In many products, the desired effect is simply achieved through this

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achieved that a smaller part of the detergent granules colored will. Such colored granules cannot be used for coloring or sprinkling toothpaste for reasons that are important to note will. Colored particles of thermosetting resin for Use in coloring, thermosetting resin compositions are described in U.S. Patent 3,095,400, however, these are particles colored with water-insoluble dyes or pigments and not suitable for use in toothpastes. The usage of relatively colorless synthetic resins as grinding and polishing agents in dentifrices is also already known, z. From U.S. Patents 2,130,034 and 3,070,510. However, there has been no suggestion of colored synthetic resins for use in dentifrices, nor has a method of coloring such resins with water-soluble dyes been disclosed.

So that dye particles become uniform or, by agglomeration to visible particles, speckled coloring of a toothpaste are suitable, the particles must not lose color and spread it out, making the entire toothpaste streaky. Since the dyes approved for dentifrice are all water-soluble and toothpastes in general are significant Containing amounts of water, it was previously not possible to find suitable to produce color-fast particles for this purpose.

It has now been found that colored finely divided resins can be used can be produced from non-toxic, water-soluble dyes and these resins are excellent as creampaste pigment or, if the particles are agglomerated, suitable for sprinkling toothpaste.

In broad terms, the process of the invention is that a water-soluble monomer or resin in an aqueous Solution of a water-soluble, non-toxic dye is polymerized under conditions which result in an essentially waterproof, crosslinked, thermosetting donut, highly polymerized Lead resin of the type described below.

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The aim of this invention is therefore a process for the production of novel colored resin particles ₉ which are suitable for use as toothpaste pigment or, in agglomerated form, for use in speckled toothpastes, and which are colored with non-toxic, water-soluble dyes, but are colorfast and Do not bleed in the presence of water, as they give off their color to the environment »

The inventive method for preparing colored, largely waterproof offset ,, ,, highly polymerized synthetic Harapartikeln from aqueous solution has a key, novel feature of which consists in that a non ^ toxic, water-soluble dye considerable time before the completion of the polymerization in W the solution is dissolved.

It has been surprisingly found that _t the resin particles formed by polymerization in the presence of Färbstofflösung assume the hue of the dye, and thus form colored resin particles, which are extremely colorfast. When used for uniformly coloring a toothpaste, a sufficient amount of the resin pigment particles can additionally serve as an abrasive and polishing agent, as long as the particle size is within a certain range explained below.

The resins obtained after the treatment according to the invention for dyeing ^ of toothpaste are suitable, are essentially water-impermeable, cross-linked, heat-hardness, strongly polymerized resins, whose monomers and precursors are soluble in water and can be polymerized in aqueous solution. A thermosetting one Resin is a? Resin that solidifies when heated and cannot be melted again. This behavior is based on education of crosslinking points between the polymer chains during the chemical reaction caused by heat or with chemical Funds is funded. The resulting three-dimensional, polymeric network is the type of structure that is required to achieve the To achieve desired color fastness, which can be effected according to the invention in a dye solution.

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An "essentially water-impermeable resin" is to be understood as meaning a resin which does not absorb any appreciable amount of water even after prolonged contact with water. The water absorption in 24 hours "at 2t> C, measured according to ASTM D-57O-57T, should preferably be less than 1 #. The absorption of water leads to the swelling and softening of the resin particles and to the bleeding of the dye Thermosetting plastics which are unsuitable because of their relatively high water absorption. It is suspected that dye molecules are "trapped" within the three-dimensional cross-linked structure of the thermosetting resin, and that, due to the impermeability of these resins to water, the enclosed molecules become largely "waterproof" and even in the presence remain colourfast from water.

Preferred types of thermosetting, crosslinked, synthetic resins which can be colored in accordance with the present invention include the highly polymerized oxygen formaldehyde, melamine formaldehyde, melamine urea formaldehyde, and phenol formaldehyde. These resins can be produced from these monomers either by polymerizing the corresponding monomers or by further polymerizing water-soluble, low molecular weight resins. The low molecular weight, water-soluble resins which can be used to prepare the final insoluble resin particles are conventionally prepared by thermally accelerated polymerization in the presence or absence of a catalyst. In the practical implementation of the polymerization, pressure is used in addition to heat in some cases, ζ. B. in molding processes. The finished resin is formed by an acid-catalyzed polymerization in which the water-soluble monomer or the low-molecular resin is converted in an aqueous solution. The type of acid catalyst is not critical, but strong acids such as H ₂ SO. preferred. The polymer precipitate formed is dried and ground and / or sieved to an appropriate particle size. The precipitated resin is preferably subjected to a further heat treatment to an even higher degree

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to achieve polymerization and crosslinking, either before or after crushing to an appropriate particle size «This the latter heat treatment makes the resin extremely hard and brittle, and these properties make the resin suitable for use suitable as a cleaning and polishing component of dentifrices.

For the purposes of the invention it is important that the polymeric material be in a finely divided form. The resin may fail in the acid-catalyzed polymerization in finely divided form, in which case particles of the desired size, "can be separated by sieving, as mentioned, and the remaining particles may be to the desired size by conventional milling methods z w. B. in impact ", ball or Hohrmühlen" can be reduced. Where the resin precipitates in bulk, the entire bulk can be ground and sieved to achieve the desired particle size. If a final heat treatment is used to impart abrasive properties to the resin, grinding to the desired particle size can be done before or after the heat treatment, but it is preferably done before the heat treatment because it shortens the time required for the heat treatment®

The geeaue composition of the hard has only a slight influence on its effectiveness as Farokomponente for tooth pastes, as long as' the Hars fulfills the conditions given above, dh..hu long as the monomers or the low molecular weight polymeric precursor in water and the finished Hars impermeable to water "cross-linked and thermosetting is.

The resinous materials of the present invention consist of particles which essentially all have a diameter of less than 500 m. And, if the Hars is to be used as a cleaning and polishing component, preferably a diameter of less than bO / U. ha03B. ο Larger particles cause a grainy Gssetonsek in the mouth and remain visible ο teeth ¹ MaHgSM ₀ The mean diameter of the particles is for optimal abrasion effect "around

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5 to about 40 / rev and preferably at t? up to 20 / rev. Larger particles can be used to produce speckled agglomerates, which will be described in more detail below. The hler listed particle diameters are microscopically using of a calibrated eyepiece.

Any water soluble dye can be used for coloring resin particles can be used according to the invention. However, since the particles are intended to be incorporated into a product that enters the mouth, Such water-soluble dyes are preferably used. det, die-'i'Ur use in products for the human Bodies are allowed. To this end, the

FDAC materials, such as B- .:

ü'D & Q-.alau No. 1 : Brillant-ülauj disodium salt of 4- £ Q- (N-Ethyl-p-eulfobenzyxamlno) phenyx] (2-sulioniumphenyx) niethylen Γ1- (N-ethyl-Np-sulfobenzyx) - ^ 2 _> 5-cyclohexadienimine ^ ;

FD & Q blue no. Ι Indigotine disodium salt from «Sr ^ '- ^ digotine disulionic acid

FD&Q Green No. 1 : Guinea Green B monosodium salt of 4- ζ4- (N-ethyl-p-sulfobfcinzylamino) diphenyxmethyxeii3 - £ i- \ N-ethyx-Np-sulionium benzyx) - ^ ¹ ^ -cyclohexadienimine};

FD&C itot No. Z x Amaranth iTinairium Salt of 1- ^ 4-Sulio-1-napthylazo) -ii-naphtol-3, Fe-ulionic acid;

FD & O-Rot Mr. D i Erythrosine Disodium SeLz of. 9-o-carboxy-phenyl "6-hydroxy-2,4" 3,7-tetrajoa-3-isoxanthoid) j ^V

FPabO-itot "jir. 4 : Ponceau; Sjt-disodium saxz of. 2- (5-Bulio- 2 , 4-xylylazo) -l-naphthol-4-auifonsjfäure;

No. 5 i Tartrazinj i'rin Sodium Salt of i-Carboxy-S-

i2ydroxy-i-sulfophenyl-4-p-sulfopnenylazopyrazol®;

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FD&C Yellow No. b t Dusk Yellow; Disodium salt of 1-p-sulfophenyxazo - <; - naphto.i-6-sulfonic acid; ⁽

FD & C-vioiett är. 1 s Acid Violet j 6B ™ monosodium salt of

4- (£ 4- (N-ethyl-p-sulfobenzylamino) phenyl [- | j- (N-ethyl-p-sulfoniumbenzylamino) phenyl] methylene) - (N, N-dimethyl- ^ ⁹ ^ -cyclohexadieneimine) $

The amount of dye used in the method of the invention depends on the relative color effect desired and the color properties of the selected dye. In general P can be the concentration of the dye from about 0.001 # to about 0.30 # based on the weight of the reaction mixture will suffice. -The primary color characteristics are a) hue, b) luminosity or value, and c) saturation, purity or depth. The hue can can be selected at will from the full range of non-toxic, water-soluble dyes available. According to the Munsell color system (Munsell Bock of Color, Munsell Color Co., Inc., Baltimore, Maryland, 1929) the finished resin preferably has a Munsell value of about 4 to 7 and a Munsell color depth of over 4.

According to another colorimetric system (J.Opt.Soc.Am., ^ 1940) the apparent reflectivity of the resin is preferably about 0.20 to about 0.45 »and the excitation purity, though slightly fluctuating from color to color, should be over 2OfS lie. The concentration of the dye used should be preferable be so high that the specified color values are achieved.

Although there are numerous processes for the preparation of essentially colorless resins by polymerizing the monomers or water-soluble ones Resins from aqueous solution are known below several examples of the production of colored resins are described in which the new process step of dissolving a water-soluble dye in an aqueous solution of the reactants before the polymerization according to the

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lying invention is carried out ι
example 1

Green urea-formaldehyde resin particles were produced by the following method in accordance with the present invention

56,065 (parts of distilled water were placed in a reaction vessel equipped with a steam heating mantle, stirrer and thermopile. The stirrer was turned on and the water was heated to 69 °. 13.235 parts of urea were dissolved in the water, the temperature of the solution increasing 49 ⁰ O. To the urea solution, 0.025 parts of powdered FIMbC Blue No. 1 and 0.025 parts of FMC Yellow Hr. 5 were added and mixing was continued until the dyes had completely dissolved, to the colored urea solution was added 30.615 parts A 37% stabilized formaldehyde solution and then slowly 0.031 part concentrated sulfuric acid were added. The reaction mixture was then heated to 49 ° C. and the reaction began, as indicated by a sudden lightening of the color of the reaction mixture. As the reaction proceeded, the temperature of the mixture rose to 66 ° -710 during the first 10 minutes.

After the reaction temperature had reached a constant value, the mixture was cooled to 49 ° C. and allowed to react at this temperature for 2 hours with constant stirring. The mixture was then placed in a filter centrifuge, the resulting cake of solids was washed with water and placed in a dryer. The solid cake was dried at 104 ⁰ C to a moisture content of less than $ 10. The dry resin was pulverized to break up any lumps and the mass was sieved through a USBS No. 40 test sieve (420 / u). The colored resin particles were further crushed to a particle diameter of 10 microns by grinding in a ball mill. The resulting portion possessed a green color (Munsell-Werfc '4-7. Muri3ell color depth ^ 4) and proved to be faroechfe in the presence of Was-aer.

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In the process described above, the critical ones Components in the reaction mixture are the dye, the urea, the formaldehyde and the acid. So that the reaction take place Then all reactants must be present in the mixture be. The order in which the respondents are added is the order of the day therefore practically irrelevant. Preferably, however, the dye is added to the mixture before the last of the reactants.

In this example, the dye was added in powder form, but it can also be added to the reaction agent in water dissolved and added as a concentrated aqueous solution. The total amount of water used in the reaction mixture P should · if the dye is added to this orphan that Take into account the amount of water in the dye solution. The dyes used in this example can be replaced by any or more of the above-listed dyes are replaced, with color-fast resin particles are obtained, which with those of the above are identical except for the color.

The 37% formaldehyde solution used in this example was stabilized with 6-896 methanol. Formaldehyde is commercially available in the form of methanol-stabilized aqueous solutions (1-12 $ methanol) with concentrations from 37 to t> 0 $, and available in the form of a white, crystalline powder (paraformaldehyde). Any of these forms can be used in the present invention, but if paraformaldehyo. is used, it must be dissolved in water with the help of a strong base, and then larger concentrations of H ₂ SO. required to catalyze the polymerization of urea and formaldehyde.

The catalytic effect of the acid depends on the hydrogen ion concentration in the iteration mix and this in turn by the degree of dissociation of the acid and its concentration in the reaction mixture away. Thus, any other acid can be used instead of Η ,, ΒΟ. Larger amounts · are used in this procedure but required if weaker acids, ie acetic acid,

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be used. The strong mineral acids are preferred used.

In the example, the water was ^{heated to 69 °} C. before the urea was added, but this is not critical. Without preheating, when urea is added, the water temperature falls below 49 ° C., the preferred temperature for initiating the reaction. However, the temperature of the mixture with the progress of reaction increases to 66-71 ⁰ C.

The reaction time can be varied within a wide range. It should be long enough to produce a sufficient yield to ensure z. B. at least about 30 minutes, but reaction times of more than 3 hours only increase the yields insignificant and the implementation should be canceled within this time.

Colored melamine-formaldehyde resin can according to the invention Process can be prepared by modifying the process described in US Pat. No. 3,251,800 to such an extent that a dye is dissolved in the first reaction stage. Colored resins of this type are obtained by following the procedure of the following example.

Example 2

3000 parts of a water-soluble melamine-Fonnaldehyd resin (Resimene 817 of Monsanto Chemical Co.), 6 parts of FDftC Red Ht, 2 and 150 parts of sodium chloride are dissolved in 7000 parts of water and heated to 60 ⁰ C. A solution of 240 parts of concentrated nitric acid in 6500 parts of water at 60 ⁰ C is quickly poured into the Färbstoff / resin solution. The resulting mixture is stirred by two turns of a spatula and the movement of the mixture is quickly stopped by lowering a jet array of baffles into the mixture. After 10 minutes, the resulting resin gel is cut into sectors and removed from the reaction vessel. Water becomes out of the gel

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pressed out, after which the gel is spread in a thin layer and dried in an oven at 100 ° C; the dried resin is then cured for 16 hours at 110 ⁰ O. The hardened resin, which consists of agglomerates of small, red particles, is placed in a ball mill and ground to a particle size of 5 to 15 microns mean diameter. The resulting, highly crosslinked, water-impermeable, thermosetting red resin particles are color-fast and do not lose any color when they are placed in water. This resin has a Munsell value of 4-7 and a Munsell depth of color greater than 4. Similar results are obtained when the FD&C Red # 2 is replaced with an equivalent amount of any of the above-listed dyes.

Colored melamine-formaldehyde-urea resins can also be inventively. can be manufactured as follows?

Example 3

100 parts of a commercially available, water-soluble melamine-urea-formaldehyde resin (TS 5913 from Monsanto Chemical Co.), with a melamine! Urea: formaldehyde ratio of 1: 1: 4 »5, and 2.5 parts FDAC violet no. 1 weraen in 250 parts of water dissolved at 60 ⁰ C. 20 parts concentrated hydrochloric acid (38 Ji)

are poured in and mixed with the dye / resin solution.

The movement of the mixture is interrupted and it solidifies into a gel. After the gel has been read (generally after a few minutes), it is removed from the reaction vessel and heat set at 150 ° for 16 hours. The hardened resin is placed in a ball mill and used to .Particles with a medium Crushed about 10 microns in diameter. The resulting waterproof, highly cross-linked, thermosetting resin particles have a purple Faroe, and uieBe Faroe doesn't bleed, when the particles are put into water. This resin has tinen liunseli value of 4-7 and a Munsell color depth of over 4.

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Similar results are obtained when the violet dye of this example is anced with an equivalent amount of wira replaces non-toxic, water-soluble dye.

Colored particles from a phenol-normaldenyd resin are produced, adding a water-soluble dye in the aqueous Solution of formaldehyde is dissolved before the formaldehyde is reacted with phenol. The manufacture of essentially- colorless war ζ en by reacting formaldehyde with phenol is im USA Latent 3,357,950. The example below explains the production of colored resins by modifying this patented process in the sense of the present Invention.

Example 4

400 parts of formaldehyde (37 # strength, aqueous solution stabilized with 11 # methanol) are placed in a reaction vessel. 4 parts of FD & C_.ölau No. 1 are dissolved in the formaldehyde solution. 2u0 parts of phenol and 20 parts of sodium hydroxide are added to this solution,
heated.

given. The solution is mixed and heated to 94-97 C for 45 minutes

5 parts Maleinanhyarid, 63 parts of citric acid and 100 parts of deionized water are slowly added to the iteaktionsgemisch while the temperature is maintained at about 95 ⁰ C. Heat is then applied to dehydrate the mixture at 105 ° 0 40 minutes. The solid residue is removed from the reaction vessel and placed in boiling water for 2 hours. After this biedehärtung the solids in 10,000 T _e is done ile water at 25 ⁰ O ,, which όθ parts of sulfuric acid were added. The water is then removed and the solid is dried and ^{hardened at 85 °} C. in an air circulation oven for 16 hours.

The blue phenol-formaldehyde resin formed is put in a ball mill crushed to a particle size of 5 to 40 microns,

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and these particles are placed in boiling water for 1 hour and then air-dried at room temperature. The end product is a color-fast, blue, highly polymerized, cross-linked, thermosetting, finely divided phenol-formaldehyde resin. Of the Munsell value of this resin is 4-7 »and the Munsell color depth is above 4.

Toothpastes generally contain a cleaning and polishing agent, a foaming agent, a humectant Thickeners or binders, flavorings and sweeteners and water. In the absence of a dye or other coloring substance these components result in a product that is generally a

P is white in color. Most of the toothpastes available on the market are in fact white. Toothpastes of other colors are also available, and these are made by dissolving a dye in the water component of the paste during the mixing process When the colored resin particles of the above examples are used as cleaning and polishing agents, will act the colored particles as a pigment which evenly colors the toothpaste in the desired shade. You total of resin particles in toothpastes for cleaning and polishing purposes is about 10 to about 90 ° C., and preferably about 20 to about 60 wt. #. The depth of color achieved depends on the depth of color of the particles themselves and their concentration in the finished paste

^ from.

Example 5

A toothpaste containing a representative colored resin that acts as both a pigment and a cleaning and polishing agent is used, is prepared according to the following recipe:

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Weight ^

Green urea formaldehyde resin 25.0 (Example 1)

Glycerin 30.0

Hydroxyethyl cellulose 1.5

Sodium Lauryl Sulphate 1 »5

Flavors 0.9

Saccharin 0.2

Tin (II) fluoride 0.4

Water rest.

This toothpaste is an even green color and is free of color strips. It is an effective way of cleaning teeth with a minimum of abrasion.

If the resin used in this toothpaste is replaced by the Resins prepared in Example 2, 3 and 4 are then replaced Obtain uniformly colored products.

Agglomerates of the resins of these examples can be prepared and these are used to make speckled toothpastes will.

The information about percentages and parts relate to the weight, unless otherwise stated.

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Claims (8)

Claims ■ n _y . Process for making colored, essentially
waterproof, crosslinked, highly polymerized
Synthetic resin particles by polymerization in aqueous solu- h solution, characterized in that it is not a toxic completed before polymerization in the aqueous solution dissolving water soluble dye. 2. The method according to claim 1, characterized in that the Resin is a mixed polymer of melamine and formaldehyde. 3. The method according to claim 1, characterized in that the resin is a mixed polymer of melamine, urea and formaldehyde is. 4. The method according to claim 1, characterized in that the Resin is a mixed polymer of urea and formaldehyde. 5. The method according to claim 1, characterized in that the resin is a mixed polymer of phenol and formaldehyde. 6. The method according to claim 1, characterized in that an aqueous solution of the dye and a water-soluble reaction product of melamine and formaldehyde, the formaldehyde / melamine molar ratio between about 2s1 and
about 4: 1 and whose weight ratio to water is between about 1 * 2.3 and about 1: 3.5, and the resulting solution is ^{acidified at 50 to 85 0} O while stirring with as much acid solution as is just necessary to an even one
Achieve mixture and cause polymerization. 009882/2138 7. The method according to claim 6, characterized in that one uses melamine instead of urea in an amount up to 80 wt.%. 8. The method according to claim 1, characterized in that one an aqueous solution of the dye, urea and formaldehyde forms, this solution is acidified with so much strong mineral acid to catalyze the polymerization, the precipitated resin wins and dries, and the dried resin mills to a particle size below about 500 microns. For The Procter & Gamble Company Cincinnati, Ohio, V.Bt.A. Lawyer 009 882/21 38 BATH