AMANTECH

(C.I. PIGMENT WHITE 24)

ALUMINA HYDRATE -1512

C.I. Constitution Number: 77002

MAIN END USE APPLICATION(S):

• PRINTING INKS
• PAPER

OTHER APPLICATIONS:

As an Extender & Filler Pigment in:

• Leather Cloth
• Cosmetics
• Crayons
• Matches Chemicals
• Polishing Agent
• Ceramics and Refractory
• Ceramic Colors
• Adhesives
• Rubber
• Paints

MANUFACTURE AND PROPERTIES:

• Alumina Hydrate is generally prepared from Aluminium Sulfate (iron free) and Sodium Carbonate. After washing, the resultant product can be dried by the aid of hot air currents. It is then pulverized. The white powder consists of anglomerates of a pigment made up of very small particles. The chemical make-up of this hydrate can be represented by:

(Al₂ [OH]₆) x (Al₂ [SO₄]₃) y

• The values for x and y depend upon the conditions during the manufacture. However, the value for x is considerably greater than the value for y. The specific gravity of the dried hydrate is 2.43 and the refractive index is 1.535. The pH value is 6.3 to 6.7 and that signfies that the product is acidic in chemical behavior and has livering tendency. To overcome this problem, we developed a special quality which is less prone to liver than the preceding grade. The pH value of this quality is 6.8 to 7.4 and has completely replaced the preceding grade among printing ink manufacturers.

TECHNICAL SPECIFICATIONS:

Specific Gravity : 2.43

Bulk Density : 0.32

Oil Absorption : 65 ± 5 per 100 gms.

pH : 6.8 to 9

Moisture : 22 to 26 %

Residue on Sieve of 240 Mesh : Max. 1 %

Livering : As per standard sample

Transparency : As per standard sample

Whitishness : As per standard sample

Refractive Index : 1.535

PARTICLE SIZE:

4 Microns : 93.8 %

2 Microns : 84.4 %

1 Micron : 53.1 %

0.5 Micron : 39.0 %

0.2 Micron : 35.9 %

0.1 Micron : 32.8 %

FINISH AND GLOSS:

• It has been observed that Alumina Hydrate improves the finish of dried ink films. If gloss varnish can be used, the addition of same increases the finish still further. However, the use of an excess of gloss varnish makes the print appear "varnishy" and yields relatively poor trapping in the case of multicolour printing. "Hydrate" is superior to Magnesium Carbonate, Calcium Carbonate, Blanc Fixe and Clays when it comes to a moderate finish or a high gloss. A combination of hydrate and gloss varnish is frequently used.

LITHOGRAPHIC INK EXTENDER:

• Because the Alumina Hydrate has acidic properties, it does not change appreciably the acidity of the lithographic fountain solution during the printing operation. This is not the case with alkaline extenders, such as Magnesia (Basic Magnesium Carbonate) and Calcium Carbonate. These tend to neutralize the acid in the fountain solution, for they can shift it to weakly acidic or even to the alkaline state. "Greasing" is the general failure when this happens. The hydrate is therefore a useful ingredient in lithographic inks.

TRANSPARENCY & PRINTING QUALITIES:

• In multicolour printing where inks trap over each other, it is obviously an advantage to have transparent inks after the first one. Alumina Hydrate qualifies very well as a transparent extender when an ink needs to be reduced in colour strength for multicolour printing.
• Because the particles of Alumina Hydrate are very small, it possesses suitable printing qualities. It is frequently used to improve the printing qualities of high specific gravity pigments, such as Chrome Yellows, Orange Mineral and Molybdated Chrome Orange.

USE IN MOISTURE - SET INKS:

• The majority of the moisture-set inks (often called steam-set inks) contain a resin that is very acidic in nature. This resin is a fumarated resin and has an acid value that is over 300. When carbonate extenders are present in moisture set inks, extreme foaming occurs due to the formation of copious bubbles of carbon-dioxide gas as the result of a chemical reaction involving the acidic resin.
• The selection of clays or of blanc fixe as extenders in these inks is not entirely satisfactory because of their relatively poor printing qualities. In a number of inks, a blend of clay and Alumina Hydrate can be used as the extender to arrive at a low cost and acceptable printing qualities. However, if the printing run be a long one, it is safer to select a good printing extender to prevent piling on the rollers and on the printing plates.
• Strangely enough, Alumina Hydrate does not seem to body up more than a trace when the fumarated rosin vehicle is used. Zinc Oxide and Orange Mineral liver readily with this vehicle.

PREVENTION OF FADING BY ALKALIES:

• More present day pigments are faded or changed in hue by alkaline substances than by acidic ones. The majority of the Triphenylmethane and Diphenylmethane pigments, such as Methyl Violet and Alkali Blue, shift their chemical structures to the colourless state when alkali is present. The popular Iron Ferrocyanide Blues readily fade with alkalies.
• If Calcium Carbonate or Magnesium Carbonate (Magnesia) are selected in the ink as the extender, together with moderate or low concentrations of the above pigments, fading can occur in the presence of considerable moisture.
• As an example of this, an alkali blue tint faded inside a humidified cigar box, but not on the outside label. In this case the 100 % relative humidity activated the Magnesium Carbonate-Alkali Blue reaction, yielding a fading. However, at 40 - 50 % relative humidity the reaction did not occur.
• The use of Alumina Hydrate as the extender solved the problem by preserving the blue colour at both relative humidities.
• Another example of fading occured when a parchment iron blue ink film was boiled during fifteen minutes with hot water, the iron blue faded to a weak tan colour of iron oxide. However, the change of the extender to Alumina Hydrate, which is mildly acidic, preserved the blue colour.
• Thus, the use of Alumina Hydrate, is a safeguard in cases where alkaline materials can be activated by the presence of sufficient moisture that can yield fading of sensitive pigments.

LIVERING:

• There is a possibility of livering when a pigment is able to react with a vehicle or its component, yielding a metallic soap.
• If the product has approximately the same viscosity as the component, then only a trace or no bodying action is obtained. If the quantity of the reactive vehicle such as a resin or a heat polymerized drying oil be small, then the livered state will not be reached. And if the reactivity of either the pigment or the vehicle be low, the amount of body change will be small. Only when the pigment and the vehicle are both in high concentrations and very active will livering occur, provided, of course, that the product is highly viscous.

1512 ALUMINA HYDRATE

• has a reduced reactivity. An accelerated test can be conducted of the ink at 160 o F during three days to examine the possibility of livering, either on storage or during hot milling.
• Many of the resins that formerly livered with Alumina Hydrate have in the recent years been improved so that livering has been eliminated. Therefore, the selection of Hydrate can be made in many resinsolvent in inks that formerly could not tolerate this extender.

DRIER DISSIPATION:

• It has been observed that Alumina Hydrate yields drier dissipation in drying oil inks. This means that the potency of the drier in the ink loses its catalytic power either upon aging or upon hot milling.
• Evidently, this is a chemical action between the Alumina Hydrate and the metallic drying catalyst. It happens more with cobalt than with Lead and Manganese.

The following remedies are available to nullify the drier dissipation effect :

1. Because this is a time reaction, addition of the drier just prior to printing reduces the delayed drying and prevents a failure to dry.
2. The use of feeder driers helps to prevent a complete failure to dry. A combination of Lead Acetate and Manganese Borate is a feeder drier. Cobalt Borate can also be used.

• When the percentage of Alumina Hydrate in the drying oil ink is moderate, or in small amounts, the factor of drier dissipation is greatly reduced. In other inks, where driers are not needed, there is no influence upon the rate of drying.
• Aged drying oil inks should be checked by the printer prior to usage, in order to ascertain if the ink has lost its catalytic drying power. There are other pigments that cause drier dissipation, such as Iron Blue and Iron Oxides.

CRACKING OF COMPOSITION ROLLERS:

• Some composition rollers are made from a high grade glue and glyceral (Glycerine). It is possible for certain pigments to damage these rollers. Among them are Lead pigments that glaze the surface of these rollers, making them non-receptive to ink.
• Other pigments, such as Iron Blue and Alumina Hydrate tend to react with the glue, hardening same by a tanning action. The increase in brittleness yields longitudinal cracks in the roller surfaces. However, when the percentage of Alumina Hydrate is moderate or low in the ink, this becomes relatively unimportant.
• The cracking of the roller material is limited to composition rollers and to rollers that have a coating of composition over the rubber center. Rubber rollers and polyurethane rollers are unaffected by the action of Iron Blue and Alumina Hydrate pigments.

IMPORTANT NOTES:

• The tests and results shown were conducted in our laboratories. They do not constitute a guarantee and it is suggested that you carry out your own evaluations prior to the adoption of these products.
• The products are offered without patent protection. For this reason and before submitting orders, it is purchaser responsibility to ensure that products requested are not covered by any patent in his country.

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