DE2436204A1 - PROCESS FOR DISTORTION-FREE COLORING OF POLYOLFINS WITH ORGANIC PIGMENTS - Google Patents

Description

Process for the distortion-free coloring of polyolefins with organic pigments

When coloring polyolefins, especially polyethylene, with organic pigments, one often makes found that a number of the mechanical properties of the dyed material change over time: Es malfunctions occur, which can be summarized as delays designated. For large-volume injection molded parts, such as bottle crates, made of polyethylene higher Density, for example, one can observe deformations and shrinkages, which sometimes lead to cracking and mostly make the articles unusable. Often one occurs even after a relatively short period of use

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Embrittlement of the material. These disadvantages are related on the majority of the organic pigments, while the inorganic pigments and a minority of organic pigments behave neutrally.

The causes of the negative phenomena are still largely unknown. However, it is assumed that the typical crystallization behavior of the polyolefins is disturbed by the presence of the pigments.

It has now been found that polyolefins can also be combined with organic Pigments can be colored without distortion if you use them with a Coats of resin that is insoluble in the substrates and infusible during the respective processing. By pulling it over the organic pigments with such a resin, the direct influence of the pigments on the substrates to be colored prevented. According to the invention, a melamine-formaldehyde resin is particularly suitable, which is cured after coating. As typical examples of organic pigments, which are suitable for the method according to the invention are particularly suitable, the following may be mentioned: Perylene and perinone pigments and in particular bisazo and isoindolinone pigments.

It has proven to be advantageous when producing the pigment preparations using melamine / formaldehyde resins proved that the hardening of the coating in the presence of a protective colloid, for example the sodium salt of carboxymethyl cellulose, is performed. The use of an effective stirring and dispersing device is also advisable a stronger agglomeration of the pigment particles coated with the initially still sticky resin is largely prevented.

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It is expedient to proceed in such a way that the resin precondensate is prepared separately, which is then added to the pigment suspension. The resin precondensate is then allowed to harden ^{at temperatures of preferably 80 to 100 ° C.}

The cured pigment preparations should not have any strong mechanical effects, for example from a grinding process, otherwise the brittle coating can be damaged or rubbed off the surface of the pigments. The training the pigment preparations in polyolefin are carried out according to the customary, known processes in extruder devices Temperatures in the melting range.

The advantage of the process according to the invention is that polyolefins can be colored with high-quality organic pigments that were previously unsuitable for this purpose. Included it is surprising that the surface of the pigments with the melamine-formaldehyde resin so easily and completely cover and the coating adheres so well under normal mechanical stress from the extruder device.

The test of the influence of warpage on polyolefin by a pigment coated with a melamine-formaldehyde resin is carried out on an injection molded part, which in shape and size is designed as practical as possible. A test piece has proven to be particularly effective, which is characterized by its wheel shape with defined layer thickness differences and a has internal tension. --....

5 09807/1 U 9 originally inspected

The test specimen is clamped in a holding device on one side and pressed against it by a constant spring pressure. Then a fixed measuring pin is moved down onto the test object and the point of contact is determined. The deviation of the test object from the horizontal can be read directly on a dial gauge with an accuracy of 0.01 mm. In the examples, the delay of polyethylene HD without pigment is indicated by polyethylene with untreated pigment and such enveloped with MF resin pigment after 7 days as well as after 72 stundigen heat treatment at 100 ⁰ G,

In addition, practical tests were carried out on a large screw injection molding machine (Kraus-Maffei KM V 110) with Euro bottle crate shape carried out. The high density polyethylene was mixed with the pigment by mixing with a Nauta mixer dyed dry and processed under the usual conditions. In contrast to the bottle crates colored with untreated pigment, those with coated pigment colored boxes did not show any distortion and passed the usual tests of usability.

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example 1

With the help of a tendon-accumulating toothed disc mixer aqueous press cake of a red pigment of the formula

/ V

CONH V 7 NHOC

Contains 40.0 g pigment, dispersed in 600 ml water. Of the 1.2 g of the sodium salt of a carboxymethyl cellulose are added to the suspension, the 1% by weight aqueous solution of which is a Has a viscosity of at least 1300 cP.

The thin liquid pigment suspension is transferred into a heatable reaction vessel which is equipped with a reflux condenser, thermometer, dropping funnel, pH measuring electrode and an intensely working stirrer. The mixture is heated to 90-92 ^° C. and the pH is adjusted to 6.0 by adding dilute sulfuric acid accordingly.

The resin precondensate is now produced in a separate operation. A mixture of 10.9 g of a 30% strength by weight aqueous formaldehyde solution and 0.11 g of a 50% strength by weight aqueous solution of monoethanolamine phosphate is prepared and this is adjusted to pH 6.0 by adding 2N sodium hydroxide solution . With stirring is added 3.45 g of melamine to, heated to 60 ⁰ C and condensed after everything has dissolved melamine, for 30 minutes at this temperature.

Direct; then you dilute the resulting water-clear Precondensate with 20 ml of water and, while stirring vigorously, allows it to enter the pigment composition within 5 minutes.

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drop in pension. The pH is maintained at 6.0, the temperature should not drop below 90 ^0C. The reaction is allowed to continue for 16 hours at 90-92 ° C. and pH 6.0. The pH of the reaction mixture is then increased to about 9.5 and 290 ml of a 0.1 η aqueous solution of the sodium salt of a resin acid (for example abietic acid) are added. After about 15 minutes, the pH is adjusted to 4.0 by the dropwise addition of dilute sulfuric acid and the free resin acid is thus precipitated. Finally, it is suctioned off, washed acid-free with water and ^{dried at 75-80 °} C. to constant weight.

52 g of a powder are obtained, 75% by weight of pigment, 8.25% by weight of MF resin and 16.75% by weight of rosin acid, (e.g. abietic acid) and that for coloring large-volume Injection molded parts made of polyolefins is well suited.

The following default values are measured:

material after Default
7 days [mm]
after 72 h at 100 ^° C Stamylan 9400 colorless
(HD polyethylene of the
Staatsmijnen Holland) 10. 61 16 .23 Stamylan 9400 colored
with 0.2% untreated
Starting pigment 17th 51 27 .81 Stamylan 9400 colored
with 0.267% MF resin
coated pigment ' 8th. 32 13th .88

BATH ORIGINAL

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Example 2

In a heatable reaction vessel, which is equipped with a reflux condenser, Thermometer, dropping funnel, pH measuring electrode and an intensely working stirrer are filled in one after the other: 20 g of a red pigment of the formula

as an aqueous press cake, 0.6 g of the sodium salt of a carboxymethyl cellulose, which is in 1% aqueous solution has a viscosity of at least 1300 cP and 650 ml of water. With the stirrer switched on, the temperature is then increased to 90-92 ° C warmed up.

The resin precondensate is now produced in a separate operation. For this purpose, a mixture of 12 g of a 30% aqueous formaldehyde solution and 0.12 g of a 50% by weight aqueous solution of monoethanolamine phosphate is prepared and this is adjusted to pH 6.0 by adding 2N sodium hydroxide solution. 3.75 g of melamine are added with stirring, the mixture is heated to 60 ^° C. and, after all of the melamine has dissolved, the mixture is condensed for 30 minutes at this temperature. ■. ...

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Immediately afterwards, the resulting water-clear precondensate is diluted with 25 ml of water and allowed to drip into the vigorously stirred pigment suspension within 10 minutes. The pH is kept at 6.0, the temperature should not drop below 90 °. It is allowed for 16 hours at 90-95 ⁰ C and react at pH 6.0. After cooling to room temperature is filtered off, washed with water and at 75 - 8O ⁰ C until constant weight.

22 g of a powder containing 80% by weight of pigment are obtained, which is used for coloring large-volume injection-molded parts Polyolefins is well suited.

The following distortion values are measured: after Default
7 days [mm]
after 72h at 100 ^° C material 9. 77 14th .97 Vestolen A 6016 colorless
(HD polyethylene of the
Chemical Works Hüls) 17th 56 28 .73 Vestolen A 6016 colored
with 0.2% untreated
Starting pigment 11 .87 18th .84 Vestolen A 6016 colored
with 0.25% MF resin
dark pigment

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Example 3

In a laboratory sand mill, 20 g of the yellow pigment JBi

with the addition of 175 ml of water and 0.6 g of the sodium salt of a Carboxymethyl cellulose, which in a 1% by weight aqueous solution has a viscosity of at least 1300 cP, deagglomerates. The resulting pigment suspension is quantitatively separated from the sand (washed with a total of approx. 300 ml of water) and transferred to a heatable reaction vessel, which is equipped with a reflux condenser, thermometer, dropping funnel, pH measuring electrode and is equipped with an intensive stirrer. The mixture is heated to 90-92 ° C. and the pH is adjusted to 6.0 appropriate addition of dilute sulfuric acid.

In the meantime, the resin precondensate is produced in a separate operation manufactured. For this purpose, a mixture of 48 g of a 30% strength by weight aqueous formaldehyde solution is prepared

0.48 g of a 50% strength by weight aqueous solution of monoethanolamine phosphate and adjusts this to pH 6.0 by adding 2N sodium hydroxide solution. With stirring, 15.5 g of melamine are added, the mixture is heated to 60 ^° C. and, after all of the melamine has dissolved, condensed for 30 minutes at this temperature.

Immediately thereafter, the resulting water-clear precondensate is diluted with 85 ml of water and allowed to drip into the vigorously stirred pigment suspension within 25 minutes. The pH is maintained at 6.0, the temperature should not drop below 90 ^0C. One leaves 16 hours

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React for a long time at 90 - 95 ° C and at pH 6.0. Nachddem cooling to room temperature is filtered off with suction, washed with water and dried at 75-80 ⁰ C until constant weight.

38 g of a soft powder containing 50% by weight are obtained Pigment that is well suited for coloring large-volume injection-molded parts made of polyolefins.

The following Warpage values were measured: after 7th Default
7 days [mm]
after 72 h at 100 ^° C material 10 .18 10. 86 Vestolen A 6016 colorless
(HD polyethylene from Che
mix works Hüls) 8th .13 16. 06 Vestolen A 6016 colored
with 0.2% untreated
Starting pigment .14 12th 51 Vestoles
with 0.47o
hulltem I A 6016 colored
MF resin around
pigment

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Example 4

In a laboratory glass ball mill, 20 g of a red pigment of the formula

with the addition of 130 ml of water and 0.6 g of the sodium salt of a carboxymethyl cellulose, which in 1 wt .-% aqueous Solution has a viscosity of at least 1300 cP, deagglomerated. The resulting pigment suspension is quantitatively separated from the glass spheres (with a total of approx. 350 ml Water washed) and transferred to a heatable reaction vessel, which is equipped with a reflux condenser, thermometer, dropping funnel, pH measuring electrode and an intensive stirrer. The mixture is warmed to 90-92 ° C. and the pH is adjusted 6.0 by adding dilute sulfuric acid accordingly.

The resin precondensate is now produced in a separate operation. A mixture of 4.7 g of a 35% strength by weight aqueous formaldehyde solution and 0.054 g of a 50% strength by weight aqueous solution of monoethanolamine phosphate is prepared and this is adjusted to pH 6.0 by adding 2N sodium hydroxide solution. 1.71 g of melamine are added with stirring, the mixture is heated to 60 ^° C. and, after all of the melamine has dissolved, condensed for 30 minutes at this temperature.

Immediately afterwards, the resulting water-clear precondensate is diluted with 10 ml of water and allowed to drip into the vigorously stirred pigment suspension within 10 minutes. The pH is maintained at 6.0, the temperature should not drop below 90 ^0C. The reaction is allowed to continue for 16 hours at 90 ° -95 ° C. and at pH 6.0. Then you increase that

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pH of the reaction mixture to 9.5 and mixed with 146 ml of a 0.1 η aqueous solution of the sodium salt of a resin acid (e.g. Abietic acid). After about 15 minutes, the pH is adjusted to 4.0 by the dropwise addition of dilute sulfuric acid and so that the free resin acid is precipitated. Finally, it is suctioned off, washed acid-free with water and stored at 75-80 ° C up to Dried constant weight.

This gives 24.5 g of a powder which consists of 75% by weight of pigment and which is well suited for coloring large-volume injection molded parts made of polyolefin.

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Example 5

Instead of the red pigment in Example 4, an orange pigment of the following formula is used:

co

Otherwise, the procedure is as in Example 4 in all details and 24.5 g of a powder are obtained, 75% by weight of which is pigment and that for coloring large-volume injection-molded parts made of polyolefin is well suited.

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Claims (6)

PATENT CLAIMS IL Process for dyeing in bulk polyolefins with organic pigments, characterized in that the organic pigment is coated with a melamine-formaldehyde resin and cured. 2. The method according to claim 1, characterized in that the organic pigment with 5 to 50 wt .-% resin, based on the preparation. 3. The method according to claim 1, characterized in that the resin is cured in the presence of a protective colloid. 4. The method according to claim 3, characterized in that the resin in the presence of the sodium salt of carboxymethyl cellulose hardens. 5. The method according to claim 1, characterized in that the pigment preparation is incorporated into high-density polyethylene. 6. The method according to claim 1, characterized in that the pigment preparation is incorporated into polypropylene. 609807/1149