CA1096107A - Chrome pigments - Google Patents
Chrome pigmentsInfo
- Publication number
- CA1096107A CA1096107A CA283,766A CA283766A CA1096107A CA 1096107 A CA1096107 A CA 1096107A CA 283766 A CA283766 A CA 283766A CA 1096107 A CA1096107 A CA 1096107A
- Authority
- CA
- Canada
- Prior art keywords
- pigment
- water
- cerous
- chrome
- process according
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
- C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
- C09C1/14—Compounds of lead
- C09C1/20—Lead chromate
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
- C09C3/00—Treatment in general of inorganic materials, other than fibrous fillers, to enhance their pigmenting or filling properties
- C09C3/06—Treatment with inorganic compounds
- C09C3/063—Coating
Abstract
Ds.28997 ABSTRACT OF THE DISCLOSURE
This invention relates to a process for the manufacture of an improved chrome yellow pigment which comprises the simultaneous treatment of an aqueous suspension of a chrome yellow pigment with two treating agents which are (i) metaphosphoric acid or a water-soluble salt thereof and (ii) a water-soluble cerous salt. The treated pigment has improved resistance to sulphur dioxide and is particularly useful in the manufacture of industrial paints.
This invention relates to a process for the manufacture of an improved chrome yellow pigment which comprises the simultaneous treatment of an aqueous suspension of a chrome yellow pigment with two treating agents which are (i) metaphosphoric acid or a water-soluble salt thereof and (ii) a water-soluble cerous salt. The treated pigment has improved resistance to sulphur dioxide and is particularly useful in the manufacture of industrial paints.
Description
~96~0'7 Ds 28997 This lnvention relates to chrome plement~ of improv~d ~ulphur dioxide resistAnce and hi8h glo~s a~d to a method for their manufacture.
Accordi~g to the invention there i~ provided a process ~or the manufacture of an ~mproved chrome yellow p~gment ~hich comprises the simultaneous treatmont of an aqueous suspension of a chrome yellow pigment w~th two treating a~ents which are (1) metaphosphoric acid or a water-~oluble 6alt thereof snd (ii) a water-601ub~e cerous s~lt.
As chrome yellow plgments there are meant lead chromate yellow piBments such as primrose chromes, lemon chroms~ and middle chromee.
As water-soluble cerous s~lts there may be mentioned for example cerous chloride, cerous sulphate, c~rous nitrate and cerous acetate.
As water-soluble metaphosphate~ thcre may be mentioned for example sodium and potassium metaphosphate~ and metapho~phoric acid, but other water ~oluble salt~ may b0 used if desired. It is preferred to u~e a ~alt rnther than the free acid.
The process oi thé in~ention ~may be carried out con~eniently by adding an aqueous solution of the watsr-soluble cerous salt or water-soluble metaphosphate gradually with ~tirring to a 6uspension of the pigment in an aqueous solution of the other water-soluble treatlng agent and, preferably after ~tirring for a further ~hort time, collecting the treated pigment by for example filtration, washing with watar, and drying, for example by heatin8 in air at 70C~ It iB
however, preferred to add the two treating agents gradually and 6~mu1taneou~1y, preferably at substanti~lly equivalent rate~, to a stirred aqueou~ 6uspension of the p~gment.
P~gments of particulArly good sulphur dioxide resistance are obtained if the water-~oluble cerou~ salt and the water-soluble -- 2 - i -`
1~961(~'7 Ds 28997 metaphosphate are added to a stirred aqueous suspension of chrome pigment at approximately equivalent rates. It is however sometimes advantageous to add a minor portion, such as 10% , of the water soluble metaphosphate before commencing addition of the water-soluble cerous salt since the metaphosphate may act as a dispersing agent on the pig.nent.
The addition of the water-soluble cerous salt and of the water-soluble metaphosphate should desirably be carried out over a period of at least 15 minutes. Shorter periods may give non~uniform treatment of the pigment particles. Periods longer than 30 minutes do not in general offer significant advantage.
The treatment may be carried out on the slurry of the pigment obtained directly from, for example, a solution of sodium dichrom~te, sodium sulphate and sodium hydroxide and a lead nitrate solution, but a slightly superior product is obtained if the untreated piement is isolated, washed with water and then reslurried for treatment.
The treatment is preferably carried out at a temperature between 60 and ~0C but other temperatures outside this range may be used if desired.
The amount of water-soluble cerous salt and of water-soluble metapllosphate ar~ proferably chosen to be roughly equivalent although a moderate excess of either will not nor~ally be deleterious, and to be sufficient tG provide cerous metaphosphate ~096~0 7 Ds 28997 in amount between O.S and 20%, and more preferably between 3 and 12%
of the weight of untreated pigment.
The product of the process of invention is a chrome pigment each particle of which is coated with insoluble cerous metaphosphate which affords protection to the pigment against attack by atmospheric sulphur dioxide. This coated pi6ment is also a feature o the invention.
It is desirable to maintain the pl~ of the suspension at a suitable value, not only because of the well-known instability o~ chrome pigments in solutions of very low or very high pH, but because unsatisfactory coatings may be obtained at unsuitable pH
values. At low pH precipitation may be incomplete and at high pU
the cerium may be precipitated as hydrated oxide instead of as meta-phosphate. The preferred pH range is 6-8,5. The pH may~be ad~usted to this range by the addition as necessary of dilute acid or dilute alkali or of acidic or alkaline salts.
The process of the invention may be used in conjunction with other known methods for improving the properties of chrome pigments, It may, for example, precede, or preferably, follow .
t~eatment of the pigment to deposit coatings of oxides of metals such as aluminium, cerium, titanium, tin, antimony, manganese or silicon on the pigment.
The pigments so treated may be isolated and dried by conventional means, including for example drying in vacuo.
109610 7 Ds 28997 By th~ procees of the inYentlon pigmenta are obtained which are o~ impro~ed sulphur dioxide resistance ~hen incorporated into paint media, for example alkyd based and acrylic based paints. Thoy also show An adva~tage in superior gloss o~er other treatments which provide 8 comparable ~mpro~enent in sulphur dioxide re~istance.
Tho ~ollowing description ProYides two examples of the present invention and comparisons Or these with five pigments that are either uncoated or are coated with salts that ar~ closely related to cerous metaphosphate. In the description all tha parts and percentageo are by weight. All the examples and pigments are prepared from the same pigment suspension.
Pi~ment Suspension An untreated lemon yellow shade chrome pigment is prepared by the ~ollowing procedure.
A solution Or 219 parts Or sodium dichromate dihydrate, 93.75 parts of anhydrous sodium sulphate, 18~.75 parts of sodium chloride and 210 parts of aqueous sodium hydroxide (6peciric gravity 1.35) in 2700 part8 of water i8 added over about 30 ~inute~ with stirrin6 to 6000 parts of 0.4 mol~r lead nitrate solution at pH 4 and 20C until tho soluble lead is reduced to 0.014 molar and the pH
ra~sed to 5.2 - 5.4. Iho p~ is then raised to 5.8 by add~tion o~
aqueous sodium carbonate and the slurry heated at 70C for one hour, diluted with water to 18,0Q0 parts and allowed to settle for 18 hours.
The supernatant liquid is re~oved by decantation and the residual durry diluted to 10,000 parts and heated to 70C. 10~ Sulphuric acld i8 added to bring the p~ to 2.6 followed by a solution of 21 parts Or sodium sulphate in 100 parts of water and 20% aqueous .
.
i 1096~ D~3 28997 sodium carbonate to bring the pH to 5.5. lOt> Parts of aqueous so~um silicate (containing 24.8% silicon as SiO2 and 9.296 sodium as Na20) diluted to 250 parts is added over 15-20 minutes followed by a solution of 105 part~ of ammonium sulphate in 500 parts of water over 30 minutes. A m~xture Or 21 parts of antimonous oxide, 21 parts of citric acid and 60 parts of concentrated hydrochlor$c acid ~ then added over 10 minutes followed by 20% aqueous 60dium carbonate to bring the pH to 7Ø I~e suspension, which conta~ns about 750 parts of pigment, is stirred for 10 minutes. Thi6 suspen~ion iB used for providing treated and untreated pigments as described below.
Pi~ment 1, untreated p$gment ~or comparison purpo~es, iB obtained by filtration and washing with water of a portion of the Pigment Suspension which iB then dried at 70-90 C.
Pigments 2 to 5 and Examples 1 and 2 are obtained by adding solution~ ~
f cerium 6alts and phosphates as described below at approximately ¦ --equivalent rates over about 15 minutes to stirred portions of the Pigment SuspenRion, prepared as described above, each portion containing about 190 parts Or pigme~t at p~l 7.0 and about 70C. l~ne treated pigment~ are isolated by filtration, washing w~th water, and drying at 70-90C.
PiRment 2 32.3 Parts of 20% ceric sulphate liquor and 8.2 parts of ~odium orthophosphate, each in 250 p~rts of water.
Pif~ment 3 18.5 Parts of cerous nitrate hexahydPate and 7 parts of 60dium orthophosphate, each in 250 parts of water.
-~, ..... .. . . .
Ds 28997 Pi ment 4. 37.6 Part~ of 20% ceric ~ulphate liquor and 9.0 parts of 60dium metaphosphate, each in 250 partG of water.
PiRment 5 14.8 Part~ of calcium chloride and 10.4 parts of sodium metaphosphate, each in 250 parts of water.
Exam~le 1 11.6 Parts of cerou~ nitrate hexahydrate and 8.2 parts of sodium Rletaphosphate each in 250 part8 of water.
l~cample 2 23.2 Parts of cerous nitrate hexahydrate an* 16.4 parts of aodium metaphosphate, each in 250 part~ of ~ater.
l~cample 1 and Pigments 2-5 illustrate pigments having a coating of about 5% by weight of phosphate, and Example 2 illustrates a pigment having a coating of about 10~ by weight of phosphate. Pigoent 1 illustrates a pigment ~/hich has not been coated with either cerium or phosphate. Only Examples 1 1~ and 2 illustrate treated pigment of the ~nvention, Pigents 1-5 being described for the purposes of the following comparisons. ;
Com~arison 1 Treated pigments prepared as described in Examples 1 and 2 and Pigment~ 2-5 and untreated pigment (Pigment 1) are each incorporated into a pa~nt by the following ~rocedure.
28 g. of pigment, 23.4 g. of a 20X Rolution of an alkyd re6in in xylene and 125 g. of 3 mm. Ballotini beads are placed in a 4 oz. glAss bottle and shaken for 30 minutes. After separation from the beads the mixture i8 blended with 70.8 g. of a 50% eolution of allcyd resin in xylene and 18.8 of a butylated melamine ~ormaldehyde re6in. The blend ~8 applied in a coating o~ thickness 0.01 inch ontO a primed metal panel and the coating dried in alr for 30 mlnutes and then heated in an oven at 120C for 30 minutes.
The coating6 of the paints are te~ted for sulphur dioxide resistance in a Kesternich apparatus by the procedure of the Glerman standard method for 1096~ 7 paint panels (DIN 50018). D~ 111./73 The following results are obtained:-Pigment SamDle 3 Cycles 5 Cycles Pigment 1 (Control) 2 1-2 5Example 1 4 4 Example 2 4-5 4-5 P$gment 2 2 1-2 3 4~5 1-2 ~ 4 1-2 1 10 " 5 4_5 4_5 The resistance is expressed on a scale of 1 to 5, 1 representing complete destruction of colour and S no change. Only Examples 1 and 5 afford a considerable measure of protection against sulphur dioxide.
Compari~on 2 Paint coatings prepared as described in Compari~on 1 are J
tested for gloss by the method of ASTM Spec. D523 using a specular ~i gloss meter at an angle of 20 with a setting for black glass of 88% reflectance. , The difference in reflectance between the samples of paints from treated pigments and from untreated, pigment (Pigment 1), expressed 20 as percentage ren ectance are as follows:-Example 1 ~ 12
Accordi~g to the invention there i~ provided a process ~or the manufacture of an ~mproved chrome yellow p~gment ~hich comprises the simultaneous treatmont of an aqueous suspension of a chrome yellow pigment w~th two treating a~ents which are (1) metaphosphoric acid or a water-~oluble 6alt thereof snd (ii) a water-601ub~e cerous s~lt.
As chrome yellow plgments there are meant lead chromate yellow piBments such as primrose chromes, lemon chroms~ and middle chromee.
As water-soluble cerous s~lts there may be mentioned for example cerous chloride, cerous sulphate, c~rous nitrate and cerous acetate.
As water-soluble metaphosphate~ thcre may be mentioned for example sodium and potassium metaphosphate~ and metapho~phoric acid, but other water ~oluble salt~ may b0 used if desired. It is preferred to u~e a ~alt rnther than the free acid.
The process oi thé in~ention ~may be carried out con~eniently by adding an aqueous solution of the watsr-soluble cerous salt or water-soluble metaphosphate gradually with ~tirring to a 6uspension of the pigment in an aqueous solution of the other water-soluble treatlng agent and, preferably after ~tirring for a further ~hort time, collecting the treated pigment by for example filtration, washing with watar, and drying, for example by heatin8 in air at 70C~ It iB
however, preferred to add the two treating agents gradually and 6~mu1taneou~1y, preferably at substanti~lly equivalent rate~, to a stirred aqueou~ 6uspension of the p~gment.
P~gments of particulArly good sulphur dioxide resistance are obtained if the water-~oluble cerou~ salt and the water-soluble -- 2 - i -`
1~961(~'7 Ds 28997 metaphosphate are added to a stirred aqueous suspension of chrome pigment at approximately equivalent rates. It is however sometimes advantageous to add a minor portion, such as 10% , of the water soluble metaphosphate before commencing addition of the water-soluble cerous salt since the metaphosphate may act as a dispersing agent on the pig.nent.
The addition of the water-soluble cerous salt and of the water-soluble metaphosphate should desirably be carried out over a period of at least 15 minutes. Shorter periods may give non~uniform treatment of the pigment particles. Periods longer than 30 minutes do not in general offer significant advantage.
The treatment may be carried out on the slurry of the pigment obtained directly from, for example, a solution of sodium dichrom~te, sodium sulphate and sodium hydroxide and a lead nitrate solution, but a slightly superior product is obtained if the untreated piement is isolated, washed with water and then reslurried for treatment.
The treatment is preferably carried out at a temperature between 60 and ~0C but other temperatures outside this range may be used if desired.
The amount of water-soluble cerous salt and of water-soluble metapllosphate ar~ proferably chosen to be roughly equivalent although a moderate excess of either will not nor~ally be deleterious, and to be sufficient tG provide cerous metaphosphate ~096~0 7 Ds 28997 in amount between O.S and 20%, and more preferably between 3 and 12%
of the weight of untreated pigment.
The product of the process of invention is a chrome pigment each particle of which is coated with insoluble cerous metaphosphate which affords protection to the pigment against attack by atmospheric sulphur dioxide. This coated pi6ment is also a feature o the invention.
It is desirable to maintain the pl~ of the suspension at a suitable value, not only because of the well-known instability o~ chrome pigments in solutions of very low or very high pH, but because unsatisfactory coatings may be obtained at unsuitable pH
values. At low pH precipitation may be incomplete and at high pU
the cerium may be precipitated as hydrated oxide instead of as meta-phosphate. The preferred pH range is 6-8,5. The pH may~be ad~usted to this range by the addition as necessary of dilute acid or dilute alkali or of acidic or alkaline salts.
The process of the invention may be used in conjunction with other known methods for improving the properties of chrome pigments, It may, for example, precede, or preferably, follow .
t~eatment of the pigment to deposit coatings of oxides of metals such as aluminium, cerium, titanium, tin, antimony, manganese or silicon on the pigment.
The pigments so treated may be isolated and dried by conventional means, including for example drying in vacuo.
109610 7 Ds 28997 By th~ procees of the inYentlon pigmenta are obtained which are o~ impro~ed sulphur dioxide resistance ~hen incorporated into paint media, for example alkyd based and acrylic based paints. Thoy also show An adva~tage in superior gloss o~er other treatments which provide 8 comparable ~mpro~enent in sulphur dioxide re~istance.
Tho ~ollowing description ProYides two examples of the present invention and comparisons Or these with five pigments that are either uncoated or are coated with salts that ar~ closely related to cerous metaphosphate. In the description all tha parts and percentageo are by weight. All the examples and pigments are prepared from the same pigment suspension.
Pi~ment Suspension An untreated lemon yellow shade chrome pigment is prepared by the ~ollowing procedure.
A solution Or 219 parts Or sodium dichromate dihydrate, 93.75 parts of anhydrous sodium sulphate, 18~.75 parts of sodium chloride and 210 parts of aqueous sodium hydroxide (6peciric gravity 1.35) in 2700 part8 of water i8 added over about 30 ~inute~ with stirrin6 to 6000 parts of 0.4 mol~r lead nitrate solution at pH 4 and 20C until tho soluble lead is reduced to 0.014 molar and the pH
ra~sed to 5.2 - 5.4. Iho p~ is then raised to 5.8 by add~tion o~
aqueous sodium carbonate and the slurry heated at 70C for one hour, diluted with water to 18,0Q0 parts and allowed to settle for 18 hours.
The supernatant liquid is re~oved by decantation and the residual durry diluted to 10,000 parts and heated to 70C. 10~ Sulphuric acld i8 added to bring the p~ to 2.6 followed by a solution of 21 parts Or sodium sulphate in 100 parts of water and 20% aqueous .
.
i 1096~ D~3 28997 sodium carbonate to bring the pH to 5.5. lOt> Parts of aqueous so~um silicate (containing 24.8% silicon as SiO2 and 9.296 sodium as Na20) diluted to 250 parts is added over 15-20 minutes followed by a solution of 105 part~ of ammonium sulphate in 500 parts of water over 30 minutes. A m~xture Or 21 parts of antimonous oxide, 21 parts of citric acid and 60 parts of concentrated hydrochlor$c acid ~ then added over 10 minutes followed by 20% aqueous 60dium carbonate to bring the pH to 7Ø I~e suspension, which conta~ns about 750 parts of pigment, is stirred for 10 minutes. Thi6 suspen~ion iB used for providing treated and untreated pigments as described below.
Pi~ment 1, untreated p$gment ~or comparison purpo~es, iB obtained by filtration and washing with water of a portion of the Pigment Suspension which iB then dried at 70-90 C.
Pigments 2 to 5 and Examples 1 and 2 are obtained by adding solution~ ~
f cerium 6alts and phosphates as described below at approximately ¦ --equivalent rates over about 15 minutes to stirred portions of the Pigment SuspenRion, prepared as described above, each portion containing about 190 parts Or pigme~t at p~l 7.0 and about 70C. l~ne treated pigment~ are isolated by filtration, washing w~th water, and drying at 70-90C.
PiRment 2 32.3 Parts of 20% ceric sulphate liquor and 8.2 parts of ~odium orthophosphate, each in 250 p~rts of water.
Pif~ment 3 18.5 Parts of cerous nitrate hexahydPate and 7 parts of 60dium orthophosphate, each in 250 parts of water.
-~, ..... .. . . .
Ds 28997 Pi ment 4. 37.6 Part~ of 20% ceric ~ulphate liquor and 9.0 parts of 60dium metaphosphate, each in 250 partG of water.
PiRment 5 14.8 Part~ of calcium chloride and 10.4 parts of sodium metaphosphate, each in 250 parts of water.
Exam~le 1 11.6 Parts of cerou~ nitrate hexahydrate and 8.2 parts of sodium Rletaphosphate each in 250 part8 of water.
l~cample 2 23.2 Parts of cerous nitrate hexahydrate an* 16.4 parts of aodium metaphosphate, each in 250 part~ of ~ater.
l~cample 1 and Pigments 2-5 illustrate pigments having a coating of about 5% by weight of phosphate, and Example 2 illustrates a pigment having a coating of about 10~ by weight of phosphate. Pigoent 1 illustrates a pigment ~/hich has not been coated with either cerium or phosphate. Only Examples 1 1~ and 2 illustrate treated pigment of the ~nvention, Pigents 1-5 being described for the purposes of the following comparisons. ;
Com~arison 1 Treated pigments prepared as described in Examples 1 and 2 and Pigment~ 2-5 and untreated pigment (Pigment 1) are each incorporated into a pa~nt by the following ~rocedure.
28 g. of pigment, 23.4 g. of a 20X Rolution of an alkyd re6in in xylene and 125 g. of 3 mm. Ballotini beads are placed in a 4 oz. glAss bottle and shaken for 30 minutes. After separation from the beads the mixture i8 blended with 70.8 g. of a 50% eolution of allcyd resin in xylene and 18.8 of a butylated melamine ~ormaldehyde re6in. The blend ~8 applied in a coating o~ thickness 0.01 inch ontO a primed metal panel and the coating dried in alr for 30 mlnutes and then heated in an oven at 120C for 30 minutes.
The coating6 of the paints are te~ted for sulphur dioxide resistance in a Kesternich apparatus by the procedure of the Glerman standard method for 1096~ 7 paint panels (DIN 50018). D~ 111./73 The following results are obtained:-Pigment SamDle 3 Cycles 5 Cycles Pigment 1 (Control) 2 1-2 5Example 1 4 4 Example 2 4-5 4-5 P$gment 2 2 1-2 3 4~5 1-2 ~ 4 1-2 1 10 " 5 4_5 4_5 The resistance is expressed on a scale of 1 to 5, 1 representing complete destruction of colour and S no change. Only Examples 1 and 5 afford a considerable measure of protection against sulphur dioxide.
Compari~on 2 Paint coatings prepared as described in Compari~on 1 are J
tested for gloss by the method of ASTM Spec. D523 using a specular ~i gloss meter at an angle of 20 with a setting for black glass of 88% reflectance. , The difference in reflectance between the samples of paints from treated pigments and from untreated, pigment (Pigment 1), expressed 20 as percentage ren ectance are as follows:-Example 1 ~ 12
2 ~ 10 Pigment 2 ~ 18 Pigment ~ + 18 Pie~ent 4 +
Plgment 5 + 3 Thu8 although calciu~metaphosphate prov$des a similar impro~ement to cerous meta-pho~phate in sulphur dioxlde and-both cerou8 and ceric metaphosphate~ pro~ide~
improved eloss only cerous ~etaphosphate pro~ides a reasonable measure of impro~ement ~n both glosg and sulphur dioxide resiRtance.
Plgment 5 + 3 Thu8 although calciu~metaphosphate prov$des a similar impro~ement to cerous meta-pho~phate in sulphur dioxlde and-both cerou8 and ceric metaphosphate~ pro~ide~
improved eloss only cerous ~etaphosphate pro~ides a reasonable measure of impro~ement ~n both glosg and sulphur dioxide resiRtance.
Claims (9)
1. A process for the manufacture of an improved chrome pigment which comprises the simultaneous treatment of an aqueous suspension of a chrome pigment at a pH of from 6 to 8.5 with two treating agents which are (i) metaphosphoric acid or a water-soluble salt thereof and (ii) a water-soluble cerous salt, the quantities of the two treating agents being sufficient to provide from 0.5% to 20% by weight, of cerous metaphosphate based on the weight of the untreated pigment.
2. A process according to claim 1 wherein aqueous solutions of the two treating agents are mixed together in the presence of the aqueous suspension of the chrome pigment.
3. A process according to claim 2 wherein the aqueous solutions of the two treating agents are added gradu-ally and simultaneously to the aqueous suspension of the chrome pigment.
4. A process according to claim 3 wherein the two solutions are added at equivalent rates.
5. A process according to Claim 1 wherein up to 10% of the metaphosphate is added to the aqueous suspension of the chrom pigment before commencing addition of the water-soluble cerous salt.
6. A process according to Claim 1 wherein the quantities of treating agents used are sufficient to provide the cerous metaphosphate in an amount between 0.5% and 20%
of the weight of untreated pigment.
of the weight of untreated pigment.
7. A process according to Claim 1 wherein the untreated pigment has been isolated and washed with water.
8. A process according to Claim 1 wherein the pigment has been previously treated with other agents conventionally used to improve the properties of chrome pigments.
9. A chrome pigment having a superficial coating of cerous metaphosphate in an amount of from 5% to 20%, by weight, based on the weight of the uncoated pigment.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB3304676A GB1568710A (en) | 1976-08-09 | 1976-08-09 | Chrome pigments |
| GB33046/76 | 1976-08-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1096107A true CA1096107A (en) | 1981-02-24 |
Family
ID=10347814
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA283,766A Expired CA1096107A (en) | 1976-08-09 | 1977-07-29 | Chrome pigments |
Country Status (7)
| Country | Link |
|---|---|
| BE (1) | BE857366A (en) |
| CA (1) | CA1096107A (en) |
| DE (1) | DE2735867A1 (en) |
| FR (1) | FR2361448A1 (en) |
| GB (1) | GB1568710A (en) |
| IT (1) | IT1084397B (en) |
| NL (1) | NL7707906A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH643885A5 (en) * | 1980-05-14 | 1984-06-29 | Alusuisse | ELECTRODE ARRANGEMENT OF A MELTFLOW ELECTROLYSIS CELL FOR PRODUCING ALUMINUM. |
| US20080087189A1 (en) * | 2005-10-03 | 2008-04-17 | Sun Chemical Corporation | Security pigments and the process of making thereof |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1397442A (en) * | 1971-06-02 | 1975-06-11 | Hoechst Ag | Stabilization of lead chromate pigments |
-
1976
- 1976-08-09 GB GB3304676A patent/GB1568710A/en not_active Expired
-
1977
- 1977-07-15 NL NL7707906A patent/NL7707906A/en not_active Application Discontinuation
- 1977-07-18 IT IT2583177A patent/IT1084397B/en active
- 1977-07-29 CA CA283,766A patent/CA1096107A/en not_active Expired
- 1977-08-01 BE BE179814A patent/BE857366A/en not_active IP Right Cessation
- 1977-08-08 FR FR7724368A patent/FR2361448A1/en active Granted
- 1977-08-09 DE DE19772735867 patent/DE2735867A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| BE857366A (en) | 1978-02-01 |
| FR2361448B1 (en) | 1983-01-14 |
| DE2735867A1 (en) | 1978-02-16 |
| FR2361448A1 (en) | 1978-03-10 |
| NL7707906A (en) | 1978-02-13 |
| GB1568710A (en) | 1980-06-04 |
| IT1084397B (en) | 1985-05-25 |
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