GB1574743A

GB1574743A - Pigment formulations for pigmenting wood preservative stains

Info

Publication number: GB1574743A
Application number: GB1528977A
Authority: GB
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 1976-04-14
Filing date: 1977-04-13
Publication date: 1980-09-10
Also published as: DK163877A; DE2616419A1; DE2616419B2

Description

(54) PIGMENT FORMULATIONS FOR PIGMENTING WOOD PRESERVATIVE STAINS (71) We, BASF AKTIENGESELLSHAFT, a German Joint Stock Company of 6700 Ludwigshafen, Federal Republic of Germany, do hereby declare the invention, for which we pray that a Patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following Statement: The present invention relates to pigment formulations, their manufacture and their use for pigmenting wood preservative stains.

Wood preservative stains are used to protect wood and at the same time provide it with a decorative surface. In general, such stains contain about 80% by weight of solvent, in most cases aliphatic gasoline hydrocarbons (white spirit), about 15% by weight of alkyd resins as binders and from about 2 to 3% by weight of fungicides, bactericides and insecticides.

Usually, the pigment is directly ground into the binder solution (ie. dispersed therein) on triple-roll mills or in bead mills. Organic pigments have been found to have a number of advantages over iron oxide pigments. Because of their lower density, the organic pigments sediment less during storage. As a result, in use such pigmented stains show better constancy of hue. When the stains are used for dip impregnation, the undesirable sedimentation of the pigments occurs less rapidly, if at all. This sedimentation results in a shift in hue, above all in the case of pigment mixtures. As a result of their reduced sedimentation, stains containing organic pigments are more easily applied uniformly to wood, without showing streaks or cloudy patches when sizable areas are being painted.

In addition, organic pigments, because of their greater tinctorial strength, offer the advantage that a lower pigment content of the stain suffices. In general, from 1 to 1.5 % by weight of such pigments is used.

For this reason. organic pigments are increasingly being used not only for bright special colors, eg. green or blue, but also for normal wood hues. Thus, for example, a complete range of the various brown hues is obtainable by using carbon black, an organic reddish brown pigment and a yellow pigment.

However, it is a disadvantage that organic pigments can only be dispersed very slowly, and with difficulty, in the low-viscosity systems of the stains, so that in carrying out the dispersion, a number of problems concerned with grinding have to be resolved.

According to the invention. this is achieved, both for organic pigments and for inorganic pigments. by using pigment formulations in which the pigment is finely dispersed.

The pigment formulations of the invention comprise - based on the formulation - (a) from 20 to 70%by weight of at least one finely divided organic pigment or inorganic pigment as the colorant and (b) from 80 to 30% by weight of at least one hydrocarbon resin (as hereinafter defined) as the binders and are substantially free from organic liquids, e.g. oils. Formulations which contain from 30 to 50% by weight of pigment, based on the formulation, are preferred.

The pigment formulations have the advantage that a wood stain can be pigmented by simply introducing the formulation according to the invention into the colorless material.

Suitable pigments for use in the formulations are all colorants which are insoluble in the media used. Examples of suitable organic pigments for the formulations of the invention are copper phthalocyanines, metal-free phthalocyanines, poly-chloro-copper phthalocyanines, polybromo-chloro-copper phthalocyanines, azo pigments, pigments chosen from the quinophthalones, the isoindolines. the anthraquinones, perylene-3,4,9,10-tetra-carboxylic acid and its bis-imides. and carbon black, whilst examples of suitable inorganic pigments are iron oxides. chromium oxides and the like. Pigment mixtures may also be used. Formulations which contain organic pigments or carbon black are particularly preferred.

Since wood treated with the stains is exposed to outdoor conditions, preferred compounds, from the above categories of pigments for the pigment formulations, are those which are very fast to light and weathering and have no adverse effect on the other constituents present in the stain.

Specific examples of pigments which are fast to light and to weathering are copper phthalocyanine, hexadecachloro-copper phthalocyanine, metal-free phthalocyanine, polychloro-bromo-copper phthalocyanine, Pigment Yellow 83/C.I. No.21,108, Pigment Yellow 74/Cl. No.11,741, Pigment Red 179/C.I. No. 71,130, carbon black, Pigment Red 189/C.I. No. 71,135, Pigment Red 123/C.I. No. 71,145 and Solvent Black 27/C.I.

No.12,195.

To be satisfactory as a binder in a pigment formulation for use in a wood preservative stain the binder material the invention must be compatible with the resin(s) present as preservative agent(s) in the stain which are, as a rule, alkyd resins. Furthermore, the pigment formulation binder must also have a good wetting action on pigments which are difficult to disperse. In addition, the binder should stabilize the pigment dispersion so that good and lasting fine dispersion of the pigment in the stain is achievable even in the absence of dispersing agents or wetting agents which might interfere with the stain. In addition, the binder should be soluble in the aliphatic solvents, eg. gasoline hydrocarbons, used for the manufacture of wood stains.

From the point of view of the manufacture of the formulations, it is a further advantage if the softening point of the binder is from 100 to 1300C, since pigment press cakes can then be used for the process of manufacture.

Surprisingly, we have found that it is possible to meet these various requirements by using a hydrocarbon resin (as hereinafter defined), or a mixture of such resins, which may be of aliphatic or aromatic character, as the binder. By the term "hydrocarbon resin" as used herein is meant a resin formed during steam cracking of petroleum or a resin obtained by polymerization of olefinic material arising during such a cracking operation. The olefins, usually of 5 carbon atoms, formed during such a cracking operation may be polymerized with Friedel-Crafts catalysts to give light-colored aliphatic paraffin-like resins containing methyl groups and naphthene rings. Hydrocarbon resins of aromatic character, formed during the cracking process, are to be found in the distillation residue after the cracking process. The softening points of the said resins are usually from 75 to 110"C, whilst their mean molecular weight is usually from 700 to 2,000. These hydrocarbon resins may alternatively be referred to as petroleum resins (see Kirk-Othmer-" Encylopedia of Chemical Technology", 2nd Edn., (1966), Vol. 2 pages 248-250).

Binder resins of the above type are marketed under the names ESCOREZ 1102 and 3102 and HERCUREZ AR 85 and AR 100.

The formulations according to the invention may be manufactured by working the pigments into the binder under the action of shearing forces, in batchwise kneaders or in continuous single-screw or twin-screw kneaders. In this process, the binder is first plasticized in a warm kneader. for example a Sigma kneader, and the pigment is then worked in as a powder or as the press cake. The mixture is then kneaded, whilst cooling it, until the desired fine dispersion of the pigment is achieved. In the case of kneaders, this requires from about 0.5 to 3 hours. After having been cooled to room temeprature, the kneaded material is crushed and milled to give a powder.

The formulations according to the invention contain the pigment in a very finely divided and stabilized form. The pigment is therefore also in a very finely divided form in the stains produced with the formulations according to the invention and can be readily redispersed by shaking if a sediment has formed on prolonged standing. If formulations containing organic pigments and carbon black are used. the glazes obtained are particularly stable, so that even after standing for more than 8 days there is still no pigment sediment. Any sediment which forms after standing for several weeks can be completely redispersed by shaking or stirring.

The Examples which follow illustrate the invention. In the text which follows. parts are by weight and bear the same relation to parts by volume as that of the kilogram to the liter.

EXAMPLE 1 60 parts of an alkyl-aromatic hydrocarbon resin marketed under the name HERCUREZ AR 100 are plasticized in a Sigma kneader at 1000C and 40 parts of Pigment Red 179, C.I.

No. 71.130 are then worked into the resin in the course of 30 minutes. The heating is then switched off and the mass is kneaded for a further hour. When it has cooled, the kneaded mass is crushed and the granules are milled.

If 3 parts of this formulation are stirred into 150 parts by volume of an unpigmented wood preservative stain (for example. the stain commercially available under the name t)FUN- GOL). a dispersion which contains the pigment in a very finely divided form is obtained. The only pigment particles detectable under the microscope are less than 3,um in size. After standing for 8 days. no sediment in the dispersion is noted.

On brushing the dispersion onto a planed spruce board, a transparent, uniformly colored coating forms.

EXAMPLE 2 The procedure followed is as described in Example 1, but instead of the pulverulent pigment, the identical pigment is used in the form of the press cake.

The binder used is an alkyl-aromatic hydrocarbon resin marketed under the name t8)HER- CUREZ AR 85. Water is evaporated off by kneading at above 100"C.

The formulation obtained has the same properties as that obtained according to Example 1.

EXAMPLE 3 The pigment described in Example 1, and the binder described in the same Example, are introduced, in a weight ratio of 2 : 3, into a twin-screw kneader (ZSK 83 from Werner & Pfleiderer). The kneading zones are heated at from 50 to 600 C. The resulting formulation has similar properties to the formulation obtained as described in Example 1.

EXAMPLES 4 TO 10 The procedure described in Example 1 or 3 is followed, but instead of the pigment referred to there, one of the pigments shown in the Table below is used. Formulations which have similar properties to the formulations obtained as described in Examples 1 to 3 are obtained.

Pigment content of the formulation: 40% EXAMPLE PIGMENT 4 carbon black tPRINTEX 60 (Degussa)) 5 copper phthalocyanine (pigmentary form) 6 polychloro-copper phthalocyanine (48So Cl) 7 pigment prepared as described in German Published Application DAS 1,770,960, Example 1 8 pigment prepared as described in German Laid Open Application DOS 2,041,999, Example 1 9 Pigment Green 10/C.I. No. 12,775 10 pigment obtained as described in Example 1 of German Patent 1,544,404.

EXAMPLE 11 60 parts of an alkyl-aromatic resin (HERCUREZ AR 85) are plasticized in a dispersion kneader at from 80 to 1000C and 40 parts of red iron oxide (Pigment Red 101/C.I. No.

77,491) in the form of an aqueous paste are then worked into the resin. After evaporating off the water, kneading is continued for a further hour without heating. The kneader is then cooled and the material is crushed in the kneader.

A red stain prepared using the above formulation in the manner described in Example 1, paragraph 2. is stable for from 1 to 2 days. Thereafter, the pigment begins to sediment slowly, but can readily be redispersed by shaking.

EXAMPLE 12 60 parts of an aliphatic hydrocarbon resin marketed under the name ESCOREZ 1102 B are plasticized in a heated dispersion kneader at from 80 - 1000C. 40 parts of the pigment described in German Laid-Open Application DOS 2,041,999, Example 1, are then kneaded into the mass in the course of 30 minutes. The mass is then kneaded first for 30 minutes with heating and thereafter for 2 hours with slight cooling. After it has cooled, the mass is crushed to form granules. This product is then finely milled. The formulation is introduced into the stain described in Example 1. A stable dispersion is obtained, from which the pigment only sediments on prolonged standing. A ready-to-use colored stain is again obtained by simple shaking or stirring.

EXAMPLE 13 The procedure described in Example 12 is followed except that hexadecachloro-copper phthalocyanine is used as the pigment. On introducing the pigment formulation into an unpigmented stain (for example the stain described in Example 1, 2nd paragraph) a stable green stain is obtained. in which the pigment can be redispersed by shaking or stirring.

EXAMPLE 14 A formulation of carbon black in an aromatic hydrocarbon resin ( ESCOREZ 3102) is prepared as described in Example 12. Because of the higher viscosity of the mass in the kneader, the formulation is incorporated at 130"C.

On introducing the kneaded mass into an unpigmented stain a black dispersion is obtained.

in which the pigment is in a very finely divided form. The sediment which forms a prolonged standing can be redispersed by stirring or shaking.

EXAMPLE 15 The procedure described in Example 1, paragraph 1, is followed, except that an aromaticaliphatic resin is used as the resin. The resin is obtained by cationic polymerization of hydrocarbon cuts, of 6 to 10 carbon atoms by means of Friedel-Crafts catalysts and contains from 70 to 80 Ojo of aromatic units (indene, a-methylstyrene and vinyltoluene) and from 30 to 20% of aliphatic units (monoolefins and diolefins of 6 to 9 carbon atoms).

When introduced into a colorless wood stain (Example 1, paragraph 2), the pigment formulation obtained above gives a stable, colored dispersion which has the same properties as the dispersion described in Example 1, paragraph 2.

WHAT WE CLAIM IS: 1. A pigment formulation which comprises - based on (a + b) - (a) from 20 to 70% by weight of at least one finely divided organic pigment or inorganic pigment as the colorant, and (b) from 80 to 30% by weight of at least one hydrocarbon resin (as hereinbefore defined) as the binder, and which is substantially free from organic liquids.

2. A pigment formulation as claimed in claim 1, wherein (b) is a hydrocarbon resin of aliphatic, paraffin-like character containing methyl groups and naphthene rings.

3. A pigment formulation as claimed in claim 1, wherein (b) is a hydrocarbon resin of aromatic character.

4. A pigment formulation as claimed in any of claims 1 to 3, wherein (b) is a hydrocarbon resin having a softening point of from 75 to 110 C and a mean molecular weight of from 700 to 2,000.

5. A pigment formulation as claimed in any of claims 1 to 4, which contains from 30 to 50% by weight of (a) and from 70 to 50% by weight of (b).

6. A pigment formulation as claimed in any of claims 1 to 5, wherein (a) is an organic pigment or carbon black.

7. A pigment formulation as claimed in any of claims 1 to 5, wherein (a) is a pigment chosen from copper phthalocyanines, metal-free phthalocyanine, polychloro-copper phthalocyanines, polybromo-chloro-copper phthalocyanines, azo pigments, quinacridone pigments, isoindoline pigments, anthraquinoid pigments, perylenetetracarboxylic acid and its bis-imides, and carbon black.

8. A process for the manufacture of a pigment formulation as claimed in any of claims 1 to 7 wherein one or more inorganic pigments and/or organic pigments are dispersed in a hydrocarbon resin (as hereinbefore defined) under the action of shearing forces.

9. A process as claimed in claim 8, wherein the dispersion is effected at above 100"C.

10. A process as claimed in claim 8 carried out substantially as described in any one of the foregoing Examples 1 to 15.

11. A pigment formulation as claimed in claim 1 whenever obtained by a process as claimed in any of claims 8 to 10.

12. A pigment formulation having a composition substantially as described in any one of the foregoing Examples 1 to 15.

13. A preservative stain for application to wood surfaces, which contains pigment formulations as claimed in any of claims 1 to 7, 11 or 12.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. standing can be redispersed by stirring or shaking. EXAMPLE 15 The procedure described in Example 1, paragraph 1, is followed, except that an aromaticaliphatic resin is used as the resin. The resin is obtained by cationic polymerization of hydrocarbon cuts, of 6 to 10 carbon atoms by means of Friedel-Crafts catalysts and contains from 70 to 80 Ojo of aromatic units (indene, a-methylstyrene and vinyltoluene) and from 30 to 20% of aliphatic units (monoolefins and diolefins of 6 to 9 carbon atoms). When introduced into a colorless wood stain (Example 1, paragraph 2), the pigment formulation obtained above gives a stable, colored dispersion which has the same properties as the dispersion described in Example 1, paragraph 2. WHAT WE CLAIM IS:

1. A pigment formulation which comprises - based on (a + b) - (a) from 20 to 70% by weight of at least one finely divided organic pigment or inorganic pigment as the colorant, and (b) from 80 to 30% by weight of at least one hydrocarbon resin (as hereinbefore defined) as the binder, and which is substantially free from organic liquids.