DE2031675B2 - Process for producing colored synthetic resin particles - Google Patents

Description

The invention relates to a method for producing colored synthetic resin particles using of non-toxic, water-soluble dyes. In this process, permanently colored, essentially water-impermeable, cross-linked, high-polymer synthetic resin particles through polycondensation in aqueous Solution with dyes can be obtained for use in food, pharmaceuticals «Nd cosmetics are approved or considered safe for use in products dated human body can be absorbed. The method according to the invention is characterized in that that before completion of the polycondensation in the aqueous solution a non-toxic, water-soluble Dissolves dye.

From the Swiss patent specification 402 416 was a process for the production of colored aldehyde condensation products nitrogen-containing compounds with water-soluble dyes that form the grouping

halogen

must possess (i.e. have a cyanuric halide residue) is known. The water soluble dye will added to the monomer before the polymerization.

jo Hie end products are used to manufacture molded Formed or suitable as color pigments for technical applications

British patent specification 1057 400 relates to the Manufacture of colorless melamine phenolic resins by

Control of the reaction pH by means of colorless metal compounds. Since, in contrast to conventional melamine resins, they do not have a color of their own, these resins can, if desired, be colored precisely by adding pigments at any stage of the process .

Colored thermosetting resin particles for use in coloring thermosetting resin compositions are described in U.S. Patent 3,095,400, but these particles are included water-insoluble dyes or pigments and not suitable for use in toothpastes. The use of relatively colorless synthetic resins as grinding, polishing and cleaning agents in Dentifrices are also already known, 7. B from USA patents 2 130 034 and 3 070 510. 3 251 800 and 3 357 95G.

The invention consists over the known in that one in the production of a water-impermeable thermosetting resin of the aqueous monomer solution a dye of any structure or added with any functional groups. the only requirement missing toxicity (and of course the resistance required for the process). Surprising comes In this way, color-fast, non-bleeding particles are obtained, albeit according to the Swiss one Patent specification 402 416 only reactive dyes seemed to come into question, but the requirement do not correspond to a lack of toxicity.

The colored resin particles obtained in the present invention can be used for this. To give toothpastes an attractive and eye-catching appearance and in some cases to increase the cleaning and polishing effect of the toothpaste. One already has It has long been recognized that color plays a major role in the consumer's judgment of a product. In many cases, the role of color is to distinguish certain products from others and to point out certain ones The properties of these products.

Colored products are usually obtained by adding the desired dye to the other ingredients is mixed in before the Gan / c is mixed. As those currently used in toothpastes Colorants are all water-soluble and the toothpastes contain varying amounts of water the color is distributed and colors the entire product evenly. Another possibility To evenly color a toothpaste, very small particles of insoluble cm, colored material, e.g. B. the particles obtained according to the invention, which act as pigment, evenly to distribute. Although such a material under the magnifying glass as discrete, colored

pichen existing can be recognized, has for the 'pße eye (tie pasta an evenly colored off-jwn. The prerequisite is of course that the particles. Each serve as a pigment, colored with a dye and used for products for human consumption Is questionable.

i Although the complete coloration of a product can be very attractive to the consumer, it does yercün achieved far greater effects with sprinkled products in which a smaller amount of articles has been incorporated. which are so great that they are composed of a different color (ut are easy to see with the naked eye. If relatively large colored particles are evenly distributed earth, a product is obtained that has numerous uiscrete, well-defined centers of contrasting Color, arbitrarily but evenly distributed, contains something striking and highly distinguishable Has appearance.

Granular detergent compositions. the means colored particles have been mottled for a long time Known time. In such products, the desired effect is achieved simply by adding a minor Part of the detergent granulate is colored. Such colored granules can be obtained from obvious Reasons for staining or sprinkling a toothpaste should not be used.

So that dye particles become uniform or, through agglomeration into visible particles, speckled Coloring a toothpaste are suitable, the particles must not lose color and ausoluten and thereby making the entire toothpaste streaky. Since d · all dyes approved for toothbrushes are water soluble and toothpastes generally contain significant amounts of water not possible to produce suitable color-fast particles for this purpose.

It has been found that the use of non-toxic, water-soluble dyes according to the invention manufactured synthetic resin / particles excellent as a toothpaste pigment or if the particles are agglomerated, are suitable for sprinkling toothpaste.

In carrying out the process of the present invention, a water-soluble monomer or resin is used polycondensed in an aqueous solution of a water-soluble, non-toxic dye under conditions, which are substantially water impermeable, crosslinked, thermosetting, highly polymerized Resin of the type further described below, the resin particles thus obtained for use as a toothpaste pigment or, in agglomerated form, for use in speckled Toothpastes are suitable.

An essential feature of the process is that it is a non-toxic, water-soluble dye considerable time to complete the polycondensation is dissolved in the solution.

It has surprisingly been found that the resin particles formed by polycondensation in the presence of the dye solution take on the hue of the dye and in this way form colored resin particles which are extremely colorfast. When used for uniformly coloring a toothpaste, a sufficient amount of the pigment-like resin particles can also serve as grinding and polishing agents, as long as the particle size is within an appropriate range.

As starting materials for the invention Process one uses monomers and precursors, which are laudable in water and in aqueous Solution can be polycondensed and crosslinked. The presence of a three-dimensional, polymeric Netzwerks Ut necessary in order to achieve the desired color fastness of the procedural products.

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 should preferably be in 24 hours at 25 C, measured according to ASTM D-570-57T. 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. Casein resins are an example of thermosetting plastics which are unsuitable because of their relatively high water absorption. It is assumed that dye molecules are "trapped" within the three-dimensional networked structure of the thermosetting resin, and that as a result of the water impermeability of these resins, the enclosed molecules become largely "waterproof" and remain colorfast even in the presence of water.
Preferred types of thermosetting, crosslinked synthetic resins which can be colored according to the invention include the highly polymerized urea-formaldehyde, melamine-formaldehyde. Melamine-urea-formaldehyde and phercol-formaldehyde resins. These resins can be produced from these monomers either by polycondensation of the corresponding monomers or water-soluble, low molecular weight resins. The low molecular weight, water soluble resins that can be used to make the final insoluble resin particles are conventionally made by heat accelerated polymerization in the presence or absence of a catalyst. In the practical implementation of the polycondensation, pressure is used in addition to the heat in some cases, e.g. B. in molding processes. The finished resin is formed by an acid-catalyzed polycondensation 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 are 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 in order to achieve an even higher degree of condensation and crosslinking, either before or after the comminution to an appropriate particle size. This latter heat treatment makes the resin extremely hard and brittle, and these properties make the resin suitable for use as a cleaning and polishing component of dentifrices.

For different use cases wt it important. that the polymeric material is in particulate form. The resin may precipitate at the säurekalalysierten polymerization in finely divided form, in which case particles of the desired size, can be separated by sieving, as mentioned, and the remaining ⁶ S particles may be to the desired size by conventional milling methods, such. B. in impact, ball or Rohrmühlcn, be comminuted. If the resin fails as a block, the entire mass can

031675

ground unscreened to the desired To achieve particle size. A final heat treatment is applied to give the resin an abrasive effect To incorporate, milling to the desired particle size can be performed before or after the heat treatment, however, it is preferably done before the heat treatment because so that the time required for the heat treatment is shortened.

The exact composition of the resin has only a slight influence on its effectiveness as a coloring component for toothpastes, as long as the resin is the the above conditions are met, d. H. as long as the monomer or the low molecular weight, polymeric precursor is water-soluble and the finished resin is impermeable to water, cross-linked and thermosetting is.

Particles obtained according to the invention for use in dentifrices consist of particles which are in the essentially all have a diameter below SOO μ and. * ° if the resin is to be used as a cleaning and polishing component, preferably one Have a diameter of less than 50 μ. Larger particles cause a grainy taste in the mouth and get caught between the teeth. The mean diameter of the particles is 5 to 40 microns and preferably 5 to 20 microns for optimal abrasion. Larger particles can be used to make speckle gelomerates be used. The particle diameters listed here are microscopic determined using a calibrated eyepiece.

Any non-toxic water-soluble dye can be used for coloring resin particles according to Invention can be used. Suitable dyes are about the FD&C dyes, such as. B .:

FD&C BIau # 1: brilliant blue; Disodium salt of 4 - {[4- (N-ethyl-p-sulfobenzylamino) phenyl] (2-sulloniumphenyl) -methylene} [l- (N-ethyl-Np-sulfobenzyl) -A ² - ⁵ -cyclohexadienimin];

FD&C Blue # 2: indigotine; Disodium salt of 5,5'-Inüigotindisulfonic acid;

FD&C Green No. I: Guinea Green B; Monosodium salt of 4- [4- (N-ethyl-p-su! Fobenzylamino) -diphenylmethylene] - [1- (N-ethyl-Np-sulfoniumbenzyl) -A ^{2> 5} -cyclohexadienimine];

FD&C Red # 2: amaranth; Trisodium salt of I- (4-Salfo-1-naphthylazo) -2-naphthol-3,6-disulfonic acid;

FD&C Red # 3: erythrosine; Disodium salt of 9-o-carboxyphenyl-6-hydroxy-2,4,5,7-tetraiodo -3-isoxanthone);

FD&C Red # 4: Ponceau-SX; Disodium salt of 2- (5-sulfo-2,4-xyIylazo) -l-naphthol-4-sulfonic acid;

FD&C Yellow No. 5: tartrazine; Trisodium salt des S-carboxy-S-hydroxy-I-sulfophenyl ^ -p-sulfophenylazopyrazole;

FD&C Yellow No. 6: Sunset Yellow FCF; Dina irium salt l-p-sulfophenylazo ^ -naphthol-o-sulfonic acid;

FD&C Viülett No. I; Acid Violet 6B; Monosodium salt of 4 - ([4- (N-ethyl-p-suliobenzylamino) -phenyl] - [4 '(N-ethyl-p-sulfoniumbenzylamino) phenyl] -methylene) - (N, N-dimethyl-A ² ' ³ -cyclohexadienimine);

The amount of dye used in the process of the invention depends on that desired relative color effect and the color properties of the selected dye. In general, the

60 Concentration of the dye from 0.001% to 0.30%, based on the weight of the reaction mixture, are sufficient. The primary color characteristics are a) shade, b) luminosity or brilliance; and c) saturation, purity or depth. The hue can be chosen from the at will The entire range of non-toxic, water-soluble dyes available can be selected. According to the Munsell color system (Munsell Book of Color. Munsell Color Co., Inc., Baltimore. Maryland, 1929) preferably has the finished resin a Munsell value of around 4 to 7 and a Munsell color depth of over 4.

According to another colorimetric system * (J. Opt. Soc. Am. 1940) is the apparent reflect tion capacity of the resin preferably about 0.20 to about 0.45. and the stimulation purity, albeit from Color to color fluctuates somewhat, should be over 20%. The concentration of the dye used should preferably be so high that the specified color values are achieved.

Although numerous processes for the preparation of essentially colorless resins by Polymematiuu of monomers or water-soluble Hsr / en from aqueous solution are known, several examples are described below for the preparation of colored sharks, in which the new process step of dissolving a water-soluble dye in a : aqueous solution of the reactants is carried out before the polymerization according to the invention:

example 1

Green urea-formaldehyde resin particles were prepared according to the present invention by the following method manufactured:

56.065 parts of distilled water were added to a reaction vessel fitted with steam hot mantles. Stirrer and thermopile was equipped. The guide was hired and the water heated to 69 ° C. 13.235 parts of urea were ^: dissolved in the water, the temperature of the solution falling to 49 ° C. To the urea solution were added 0.025 part of powdered FD&C Blue No. I and 0.025 part of FD&C Yellow No. 5 and mixing continued until the dyes were completely dissolved. 30.615 parts of a 37% strength stabilized formaldehyde solution and then slowly 0.031 part of concentrated sulfuric acid were added to the colored urea solution. 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 66-71 ° C 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 solid cake formed was washed with water and put in a dryer. The solids cake was ^{dried at 104 °} C. to a moisture content of below 10%. The dry resin was pulverized in order to break up all the lumps, and the mass was sifted through a sieve with a mesh size of 420 μm. The colored resin particles were further crushed to a particle diameter of 10 microns by grinding in a ball mill. the

resulting particles were green in color.

(Munsell value 4 to 7. Munsell color depth > 4) and example 2

proved to be colourfast in the presence of water. 3000 parts of a water-soluble melamine-formaldehyde

In the process described above, hyd resin is 6 parts of FD&C Red No. 2 and 150 parts

the critical components in the reaction mixture 5 sodium chloride are dissolved in 7000 parts of water

mixing the dye of the urea, formaldehyde and heated to 60 ⁰ C. A solution of 240 parts

and the acid. To allow the reaction to proceed, add concentrated nitric acid in 6500 parts of water

all reactants in the mixture must be from 60 ⁰ C is quickly converted into the dye / resin solution

to be knowledgeable. The order in which the reactants were added. The resulting mixture is

tion participant is therefore practically irrelevant. io rotations of a spatula stirred, and the movement

Preferably, however, the dye is added to the mixture of the mixture is quickly stopped by adding in the

added before the last of the reactants. Mixture a radial arrangement of baffle plates

In this example the dye was lowered into powder. After 10 minutes the resulting

form, but it can also be cut into sectors before being added to the resin gel and removed from the

Reaction mixture dissolved in water and taken as a concentration vessel. Water becomes out of the gel

trated aqueous solution are added. The squeezed out in what the gel in a thin layer

Total amount of Was- used in the reaction mixture and dried in an oven at 100.degree

water should when the dye is added in this way; the dried resin is then at 16 hours

is, the amount of water in the dye solution into account- I IO "C hardened. The hardened resin, which consists of agglomerates

sight. The dye * o merates used in this example consists of small, red particles, is in

Substances can be put through any one or more of a ball mill and down to a particle size

The dyes listed above can be replaced, with an average diameter of 5 to 15 microns being grinded.

colorfast resin particles are obtained, which len with those. The resulting, highly networked, water-

of the above example, thermosetting red resin particles are identically permeable except for the color

are. ^a 5 are colourfast and do not lose color when they are in

The 37% form used in this example can be added to water. This resin has one

The aldehyde solution was stabilized with 6 to 8% methanol. Munsell value from 4 to 7 and a Munsell color depth

Formaldehyde is commercially available in the form of methanol- over 4. Similar results are obtained

stabilized, aqueous solutions (1 to 12% metha- if the FD&C red no. 2 by an equivalent

nol) with concentrations from 37 to 50%, and in 3 «> Amount of any of the dyes listed above

Form of a white, crystalline powder (Paraform- is replaced.

aldehyde). Any of these forms can be invented

used as intended. However, if Para- can also be prepared according to the invention as follows

formaldehyde is used, it must be obtained with the help of:

strong base to be dissolved in water, and then are 35.

larger concentrations of H ₄ SO ₄ required for example 3

the polymerization of urea and formaldehyde 100 parts of a commercially available, water-soluble

to catalyze. Melamine-urea-formaldehyde resin with a

The catalytic effect of the acid depends on the melamine to urea to formaldehyde ratio

Hydrogen ion concentration in the reaction mixture «° 1: 1: 4.5, as well as 2.5 parts of FD&C Violet No. 1

and this in turn depends on the degree of dissociation in 250 parts of water at 60 ° C. 20 parts concentrated

Acid and its concentration in the reaction mixture trated hydrochloric acid (38%) are poured in and

away. Thus, any other acid can be used instead of mixed with the dye / resin solution.

H ₂ SO _{1 can be used} in this process, larger The movement of the mixture is interrupted, and

However, quantities are required if the weaker 45 solidifies to form a gel. After the gel sets

How I ssigsäure used acids. Has become preferred (generally after a few minutes),

Strong mineral acids are wisely used. it is taken out of the reaction vessel and

In the example, the water was heat-hardened at 150 ° C for 16 hours before the urine. The hardened one

added substance heated to 69 ° C, but this is not the resin is put into a ball mill and parti-

critical. Without preheating, the urea 5 ° does not fall with a mean diameter of about

Addition of the water temperature below 49 ° C, which grinds before 10 microns. The resulting aquatic

added temperature for the initiation of the reaction. permeable, highly cross-linked, thermosetting resin

However, as the reaction proceeds, the temperature particles have a purple color, and this color increases

The temperature of the mixture is 66 to 71 "C. Does not bleed out when the particles are placed in water

The reaction time can be within a wide range. This resin has a Munsell value before

Range can be varied. It should be long enough, 4 to 7, and a Munsell color depth of over 4.

to ensure a sufficient yield, e.g. B. Similar results are obtained when dei

at least about 30 minutes, but increase the react- violet dye of this example by an equiva-

tion times of more than 3 hours the yields only a small amount of another, non-toxic, water-soluble

insignificant, and the implementation should be replaced within this ^{6o borrowed} dye.

Time to be canceled. Colored particles from a phenol-formaldehyde

Colored miamine-formaldehyde resin can be made by adding a water-soluble resin

prepared by the process according to the invention, dye in the aqueous solution of formaldehyde

by dissolving that in US Pat. No. 3,251,800 before the formaldehyde is reacted with phenol

The written procedure is modified to the extent that ⁶ 5 is set. The production of essentially coloring

a dye is dissolved in the first reaction stage. loose resins by reacting formaldehyde mi

Colored resins of this type are made by the Phenol is in U.S. Patent 3,357,950 be

ren of the following example. wrote.

9 10

The following example illustrates the manufacture are made by adding a dye in the water

of colored resins by modifying this component of the paste during the mixing process

known method within the meaning of the invention. is resolved. When the colored resin particles are the

14 above examples as cleaning and polishing example 4 _{5 m} j _tte | are used, the colored par-

400 parts of formaldehyde (37%, with 11% methanol particles as pigment, which stabilized the toothpaste in the, aqueous solution) are dyed evenly in a reac- desired shade. The total vessel given. 4 parts of FD&C Blue No. 1 are the amount of resin particles in toothpastes is for dissolved in the formaldehyde solution. To this solution cleaning and polishing purposes 10 to 90% and before being 200 parts of phenol and 20 parts of sodium, preferably 20 to 60 percent by weight. The scored hydroxide given. The solution is mixed and color depth depends on the color depth of the particles themselves Heated to 94 to 97 ° C for 45 minutes. and their concentration in the finished paste.

5 parts of maleic anhydride, 63 parts of citric acid and. .

100 parts of deionized water are slowly becoming the application example

Reaction mixture added while the temperature is 15 A toothpaste containing a representative colored

is held at about 95 ° C. Then heat is applied. Resin contains both as pigment and as

turns the mixture at 105 ° C for 40 minutes to cleaning and polishing agents, is used after

drain. The solid residue is prepared from the following recipe,

tion vessel and 2 hours in boiling weight percent

Water given ^ After this boiling hardening the * » _Green urea-formaldehyde resin .. 25.0

Solid in 10,000 parts of water at 25 ° C, which (Example I)

50 parts of sulfuric acid were added. The water glycerin 30 0

is then removed and the solid dried and hydroxyethyl cellulose 15th

Sodium lauryl sulphate .. '.'. '.'. '.'. '.'. '.'. '.'. '.'. '.' at 85 ° C in a forced air oven for 16 hours. {, 5

^ha ii ^et " u-, Λ u, ou 1 _c μ tu α u ²⁵ Flavors 0.9

The formed blue phenol-formaldehyde resin saccharin 0 2

is in a ball mill to a particle size of tin (II) FluoVid 0 4

Crushed 5 to 40 microns, and these particles become water residue

put in boiling water for 1 hour and then

air dried at room temperature. The end product 30 This toothpaste has an even green color

is a color-fast, blue, highly polymerized, and is free from color streaks. She is an effective one

Wet, thermosetting, finely divided phenolic molding agent for cleaning the teeth with a minimum

aldehyde resin. The Munsell value of this resin is based on abrasion.

carries 4 to 7, and the Munsell shade depth is above 4. Will be the resin used in this toothpaste

Toothpastes generally contain eun cleansers prepared according to Examples 2, 3 and 4

g and polish, a foaming agent, replaces resins, then become evenly colored

a humectant, thickener or binding agent, products are obtained.

Flavors and sweeteners and water. In the absence of agglomerates of the resins of these examples

means of a dye or other coloring substance and these for the production of speckled

zen these components result in a product that uses 4 ° toothpastes,

generally white in color. Most commercial- The information on percentages and parts relate

usual toothpastes are in fact white. Toothpastes are based on weight, unless otherwise stated.

of other color are also available, and this ben is.

Claims (8)

Patent claims: / I. Process for the production of colored, im essential water-impermeable, cross-linked, high-polymer synthetic resin particles through polycondensation in an aqueous solution, thereby characterized in that one iron in the aqueous solution before the polycondensation is complete dissolves non-toxic, water-soluble dye. 2. The method according to claim I, characterized in that a Pclykondensat from melamine and formaldehyde. 3. The method according to claim I, characterized in that a polycondensate of melamine, Manufactures urea and formaldehyde. 4. The method according to claim 1, characterized in that a polycondensate is produced from urea and formaldehyde. 5. The method according to claim I, characterized in that one is a polycondensate of phenol and formaldehyde. 6. The method according to claim 1, characterized in that that an aqueous solution of the dye and a water-soluble reaction product from melamine and formaldehyde, its formaldehyde / melamine molar ratio between 2: 1 and 4: I and its weight ratio too Water between I: 2.3 and I: 3.5 is formed, and the removed solution at 50 to 85 ° C below Stir acidified with as much acid solution as is just necessary to achieve an even mixture achieve and cause polycondensation. 7. The method according to claim 6, characterized in that instead of melamine urea in one Amount used up to 80 percent by weight. 8. The method according to claim I, characterized in that there is an aqueous solution from the Dye, urea and formaldehyde form this solution with so much strong mineral acid acidifies to catalyze the polycondensation, the precipitated polycondensate is recovered and dried, and grinding the dried polycondensate to a particle size below about 500 microns.