Preparation of Heat Stabilizers for Blue Pigment Copper

and Other Metal Phthalocyanines as well as other colour

of organic Pigment (Quinacridones) for Plastic and

Rubber Colourations

Benjamin Lukas

Introduction

• There is a wide range of organic pigments to choose from when we want to

colour plastic attractively.

• For coloration of any material there are demands that have to be satisfied

such as colour intensity and brilliance.

• For plastic colouration in addition to those, there are other demands such as

the pigment must be temperature resistant to the processing temperature of

the plastic which can reach up to 350 C or otherwise it will degrade rapidly.

• Majority of organic pigments are not resistant to that temperature.

• For blue colouration on plastic, the pigment is usually blue pigment copper

phthalocyanine.

Blue Pigment Copper Phthalocyanine

Blue pigment copper phthalocyanine,

CuPc, is one of the most

stable pigments towards light,

temperature and chemicals and hence,

combined with its attractive colours,

this pigment is not surprisingly the

most produced organic pigment in the

world with total over 110,000 MT per year.

In industry, copper phthalocyanine pigment is

produced in two stages:

1st : the preparation of the Blue crude CuPc

2nd : the Pigmentation of crude CuPc ie the

reduction of particle size of crude CuPc.

1st Stage : Preparation of Crude Copper Phthalocyanine

(CuPc)

Preparation of Crude CuPc Blue

Crude CuPc is commonly prepared by reacting copper chloride, urea, phthalic anhydride, ammonium molybdate as catalyst and aromatic solvent.

• CuCl + 12 H2NCONH2 + 4 C6H4 (CO)2O CuPc + NH3 + CO2 + H2O + NH4Cl

•

• Structure of CuPc Yield 90%

1st stage : Preparation of crude copper

phthalocyanine (CuPc)

Procedure for preparation of crude copper phthalocyanine:

• Phthalic anhydride 1000 kg, urea 1350 kg, and trichlorobenzene 3000 kg are

mixed in a vessel equipped with an oil bath and stirrer: 240 kg of copper(II) chloride and 5 kg of ammonium molybdate are then added.

• The mixture are heated up slowly within 1 hour to 200 C . Gas evolution mostly CO2 and some NH3 with formation of phthalimide begins at 130 C.

• Formation of CuPc begins at 160-170 C, with simultaneous released of CO2 and NH3. After stirring at 200-205 C for several hours, formation of the pigment is complete.

1st Stage: Yield of Crude CuPc 99 % using New Method

. The Phthalocyanine is filtered off, washed with hot trichlorobenzene at 50 C,

followed with methanol and then hot water.

• The wet solid is then dried in oven for 10 hours at 100 C

• The yield of CuPc is 870 kg( 90%)

• Yield can be increased up to 99% using new method that use an additional catalyst

x fatty acid ester sodium salt as reported previously on academic.edu,

slideshare.com and researchgate.net.

The co-catalyst may not be necessarily of the above formula x fatty acid ester

sodium salt.

Manufacturer who applies this new method will get at least 9% extra profit and save

more on environment which can make this manufacturer more competitive against

the same type of manufacturers.

1st Stage: Yield of CuPc 99 % using New Method

Note:

. Trichlorobenzene is no longer used as solvent for the production of metal

phthalocyanines as it produces toxic carcinogenic pcb (polychlorobiphenyl), it

is therefore replaced by alkyl benzene solvent which has similar boiling point.

. Phthalic acid/anhydride can be replaced with phthalonitrile but because

phthalonitrile is much more expensive than phthalic anhydride and also it is

highly toxic which therefore demands special care for environmental

protection, the phthalonitrile process is then too costly for industry compared

with the phthalic acid/anhydride process.

2nd Stage: Pigmentation Process

There are 2 methods of pigmentation :

1st Method

• Dissolving in conc H2SO4 and then sprayed into aqueous solution containing

certain additives like surfactant

Pigments Produced

• Blue Pigment 15:0

• Reddish blue pigment with heat stability up to 170 C and poor solvent resistant

• Blue Pigment 15:1

• Reddish blue pigment with heat stability up to 350 C but poor solvent resistant

• Blue Pigment 15:2

• Reddish blue pigment with heat stability up to 350 C and good solvent resistant

2nd Stage: Pigmentation Process

2nd

Method

• Grinding with inorganic salts with the aids of polyol solvent in the presence of

certain additive in kneader or ball mill

Pigments Produced

• Blue Pigment 15:3

• Greenish blue pigment with tendency to agglomerate

• Blue Pigment 15-4

• Greenish blue pigment with solvent fastness

1st Method: Pigmentation by Grinding to Produce Beta Pigment

Production of Beta-CuPc Pigment from Crude CuPc:

• In a kneader , 283kg of crude CuPc is ground for 8 hours with 1131 kg of NaCl and 283 kg of diethylene glycol (DEG) at certain temperature.

• Then this paste is boiled in 6000 L of water and filtered using filter press to remove water/soluble substances.

• Washing with hot water is continued until no water soluble substances can be found.

• The press cake is then dried at 70 C – 75 C or using spin flash drier. A intensive greenish blue beta-CuPC is obtained.

• Different quality of the product is obtained depending on ratio of chemicals used, the grinding time and the grinding temperature of the process.

2nd Method: Pigmentation by Sulfuric Acid to

Produce Alpha CuPc

Production of alpha CuPc Pigment from crude CuPc

• Crude CuPc 700 kg is added quickly to conc. H2SO4 (96%) 6300 kg, and the then temp

is allowed to rise to 50 C . The suspension is stirred overnight.

• When the phthalocyanine is completely dissolved , the suspension is sprayed into 35000 L of water at 70 C, and the temp is allowed to rise to 85 C – 90 C. The precipitated pigment is filtered off in a filter press and washed until acid free.

• The press cake is then mixed with 25000 L of water, and the remaining acid is neutralized with K2CO3 and ammonia. After addition of 35 kg of surfactant the suspension is heated for 1 h until a clear filtrate is obtained.

• After filtration of the suspension, the press cake is washed with hot water and homogenized with sufficient water to give a 20% paste, which is past 3-5 times thro a disintegrator (3000 rpm).

• Different quality of the product is obtained depending on the ratio of chemicals used, reaction temperature, reaction time and the size of the nozzle of the spray used as well as the addition of certain additive at the end of the reaction.

Pigment Applications

Besides coloration on plastic copper phthalocyanine pigments are also used for

various applications

• Inks : water and solvent based

• Paints : water and solvent based

• Plastics : all types

• Rubber

• Glass

• Ceramic

• Textile

• Cement Products

• Cosmetics

• For most pigments in the market, the good

quality ocan be only for 2 or 3 application only

as most application requires pigment made in

certain way with certain additive used

Heat Stability of Copper Phthalocyanine

• For certain applications like thermoplastics and enamel coating, most copper phthalocyanine pigments used are of the alpha type and so these pigments will have to withstand high temperature up to 350 C depending on the type of plastics.

• Alpha copper phthalocyanine pigments will only be able to withstand temperature up to 170 C, above this temperature the color intensity will start to drop with the shade turns from reddish to greenish and furthermore become non-homogenous.

• Heat resistance of copper phthalocyanine can be increased by the addition of chemicals called Heat Stabilizers.

• Heat stabilizers are very expensive compared to pigment, it cost at least 3 x price of the pigment

Heat Stability of Copper Phthalocyanine

Thermoplastic resin may be rubber or any of engineering plastics such as:

High Density Polyethylene (HDPE) Polyamide (PA)

Acrylonitrile Butadiene Styrene (ABS) Polycarbonate (PC)

Polyether Ether Ketone (PEEK), Polyether Sulphone (PES)

Polyethelylene Terephthalate (PET) Ethylene Vinyl Acetate (EVA)

Polybutylene Terephthalate (PBTP) Polystyrene (PS)

Preparation of Heat Stabilizer 1

Chemicals used:

Concentrated H2SO4. 700 ml

Crude copper phthalocyanine 100 g

Paraformaldehyde x g

Mono,di orTetrachloro Phthalimide y g

Oleum z g

Procedure:

. Pour concentrated sulfuric acid into a 2 liter

beaker equipped with a Homo-mixer followed by oleum

. Add little by little crude copper phthalocyanine into the beaker while stirring at

100 -120 rpm

. Add paraformaldehyde followed by chloro phthalimide compound into the beaker

Preparation of Heat Stabilizer 1

. Heat the mixture at 80-85 C for a few hours while

continue stirring at the same speed.

. Pour the mixture slowly into a beaker

containing 10 liter of water while

maintaining the temperature at

90 - 95 C.

. Stir the mixture for 15 minutes.

. Filter with the help of vacuum and wash the

wet solid with hot water until the filtrate is

neutral.

. Analyze the solid content of the wet solid

of Heat Stabilizer 1

Chemical Reactions

CH2O + C8Cl4O2N HOCH2-N(CO)2 C6Cl4

Paraformaldehyde tetrachlorophthalimide

CuPc + CH2O + C8Cl4O2N + H2SO4 (SO3H)xCuPc-[CH2-N(CO)2C6Cl4]n

Heat Stabilizer 1

Preparation of Heat Stabilizer 2

Chemicals used:

Concentrated sulphuric acid / oleum 700 ml

Crude copper phthalocyanine 100 g

Paraformaldehyde a g

Phthalimide b g

Procedure:

The same as Heat Stabilizer 1

Heat Stabilizer 2

(SO3H)x

Crucial Factors for the Process

To obtain good heat stabilizers the processes must find out the

following parameters such as:

• The concentration of acid

• The ratio of chemicals used

• The reaction time

• The reaction temperature

For example if the reaction time is

exceeded than it should be then we

would obtain not a pigment but a dye

which is soluble in water and therefore it presents a problem.

Differences btw Heat Stabilizers

Many blue pigments in the market though they are labelled

as heat resistant blue 15:1, they are in fact not good heat

resistant as they offer heat resistency less than 250 C.

This is because that some of these a do not include

phthalimide and paraformaldehyde in their reactions, so it

is just a sulfonated product produced while others do not

get the above four factors correctly.

The difference between the two heat stabilizers 1 & 2 :

-Heat stablizer 1 has greener shade

-Heat stabilizer 1 can prevent warping on final product of

the plastic

Incorporation of Heat Additive into Pigment

There are several blending methods for making heat stabilized

copper phthalocyanine, but the best one is as follows:

• The pigment wet cake together with the heat stabilizer additive wet cake with the ratio 90:10 are mixed with enough water in a blender with high speed for 3 minutes.

• The slurry is then poured into a beaker. The slurry is

then stirred at low speed and heated at 100 C for

30 mins.

• The slurry is then filtered and dried in oven for 10

hours at 80 C.

• The solid is then ground and then sieved into

uniform size powder and ready for analysis.

Procedure for Heat Stability Test

The heat stability of the pigment is determined using DIN EN 12877-1 on white

reduction using TiO2.

Materials used:

High density polyethylene (HDPE) 99.0 g

Titanium dioxide 0.9 g

Alpha copper phthalocyanine plus the heat stabilizer 0.1 g

Procedure:

• The alpha copper phthalocyanine pigment is milled and sieved through a 150

micron screen.

Procedure for Heat Stability Test

• Into a two-roll mill, with the rollers set at 150C and the gap

between the rolls at 0.3 mm, the mixture of HDPE with TiO2 and

the pigment sample prepared previously is introduced .

• After milling, cutting, folding and reworking for 8 minutes, the gap

is adjusted to 1.5 mm, and the compound obtained as thin

homogenous sheet is allowed to cool to room temperature and

then it is chipped.

Two Roll Mill & Gap

Plastic Injection Moulding Machine

• The chipped material is fed to an injection moulding machine

with the barrel set at 180 C.

• Once the feed is running uniformly through the machine, HDPE

moulding is obtained which has a strong blue shade.

Procedure for Heat Stability Test

• The procedure is repeated several times with the barrel temperature being

increased to 350 C in 20 C steps, with a 5 minute dwell time at each

temperature.

• The heat stability denotes the highest temperature at which there is no

noticeable change in color shade

• To increase or lower the heat stability of the sample as required is just by

increasing or lowering the amount of the heat stabilizer added.

• 15 % addition of this heat stabilizer to CuPc pigment would stabilize that

pigment up to 350 C

Finally

The heat stabilizers reported here can be used to increase the heat

resistance of copper phthalocyanine and also of any blue pigment of any

metal phthalocyanines such iron, cobalt, nickel, zinc and

tin phthalocyanine in coloring plastic materials or even

better if the heat stabilizer additive is made using

those metal phthalocyanines as the reagents

using the same method presented here.

MPc + CH2O + C8H4O2N + H2SO4

(SO3H)x MPc-[CH2-N(CO)2C6H4]y

Finally

The question now what are the heat stabilizers used for other pigment classes eg

Quinacridones and azo pigments used for plastic application?

Quinacridones are class of pigments which have brilliant color range from

yellow, orange, red, magenta to violet. When we replace metal phthalocyanine

molecule with quinacridone molecule in the reaction then we will have good

heat stabilizer for quinacridones if we apply the correct parameters for the four

crucial factors as for the heat stabilizer for copper phthalocyanine.

Quinacridones + CH2O + C8H4O3 + H2SO4

(SO3H)x Quinacridone-[CH2-N(CO)2C6H4]y

Thank you………………

For consultation of this project and others previously

reported please contact :

benjaminlukas@yahoo.com