DE2312372A1 - ABRASIVE AND POLISH SUSPENSIONS - Google Patents

Description

PATENT ADVOCATE DR. HANS-GUNTHER EGGERT ₁ DIPLOMA CHEMIST

5 COLOGNE 51, OBERLÄNDER UFER 90 £ · $ \ Δ3Ι £

Cologne, March 6, 1973 Eg / Ax / pz / 37

Union Carbide Corporation, 27o Park Avenue, New York, N.Y. 1OO17 (U.S.A.)

Abrasive and polishing agent suspensions

The invention relates to suspensions of abrasive and polishing agents, in particular permanent suspensions of powdery form Abrasives in a non-aqueous or partially aqueous glycol as a carrier.

Grinding and polishing agents are suspended in a wide variety of water-based solutions. These are currently available Suspensions are not persistent because the abrasive particles settle and to the bottom of the container caking. They also have water-based suspensions a high rate of evaporation, which requires the periodic addition of liquid to maintain the properties of the polishing compound on the lapping tool.

It has now been found that permanent suspensions of powdery abrasives and polishes are produced can be used if suspending agents are used which '

309838/1179

contain a non-aqueous or partially aqueous glycol.

In accordance with the invention it has been found that the glycol-based suspending agents can be treated so that they the abrasive particles remain in suspension hai - so that they do not settle or at the bottom of the container caking, as is the case with the currently available metallographic and semiconductor polishing agents of the Case is. Furthermore, the suspending agent has a tendency due to the low vapor pressure of the glycol serving as a carrier substance not to dry out. The rate of evaporation is reduced to a minimum, and the periodic addition of carrier substance to maintain the properties of the polishing agent on the lapping tool is not necessary. Another factor that contributes to the fact that the carrier substance of the suspensions according to the invention does not dry out, is the high hygroscopicity of the compounds from the glycol group. For example, loses a 5o% aqueous ethylene glycol solution at 27 C or 60% relative humidity maximum Io% of their water through evaporation.

The suspensions according to the invention have the further advantage that glycol-based suspensions are completely in the water soluble and are soluble in many organic materials that are normally insoluble in water. this is an advantage over oil-based lapping fluids. Furthermore, suspensions based on glycols have as

309838/1 179

Carriers have a much wider usable temperature range. Pure ethylene glycol as a carrier substance would be between -12 and 2oo ° C, i.e. over twice the range compared to pure water, be liquid. There are also glycols reduce the surface tension in aqueous systems, they guarantee excellent wetting properties by their presence in the polishing suspensions.

According to the invention, various glycols, e.g. ethylene glycol, diethylene glycol and triethylene glycol, however, ethylene glycol is preferably used alone or in combination with the other glycols and / or water. The as Carrier substance serving glycol is used to thicken the suspension and to form a permanent suspension of A high molecular weight carboxypolymethylene polymer is added to abrasive particles in the glycol or glycol-water mixture. Suspensions prepared according to the invention have a shelf life or useful life of more than one year without the abrasive particles settling.

Any polishing agents can be used according to the method according to FIG Invention to be suspended. Typical powders are aluminum oxide powders with a mean particle size (im non-agglomerated state) in the range from about o, o5 to l, ou (Handel name Linde type A, B or C "Manufactured by the applicant") · As further suitable Polishing agents come, for example, from silicon carbide, Sea sand etc. in question. Suspensions of these and other powders are described in the following examples which illustrate the Explain the invention further.

3098

According to the invention, the suspensions are prepared as follows: A high molecular weight carboxypolymethylene polymer such as the product of the trade name "Carbopol 941" (manufactured by B.F. Goodrich Chemical Co.) is mixed with ethylene glycol. The carboxypolymethylene "Carbopol 941" is available as a dry, flaky powder in acidic Form supplied that requires neutralization to develop optimal properties. Therefore, after mixing of the carboxyροIymethylene to the ethylene glycol an aqueous Solution of a base, e.g. ammonium hydroxide, sodium hydroxide or an organic amine, the mixture of carboxypolymethylene and glycol are added to neutralize the carboxymethylene, forming a thick slime. That Powder to be suspended is dispersed either in a glycol or in water or in mixtures of glycol and water. The dispersion is added to the glycol-based slime and mixed well therewith, the suspension according to of the invention is formed.

The suspension formed consists essentially of one Grinding and polishing powder, which is in a medium of glycol, which with a neutralized carboxypolymethylene polymer is thickened, is suspended.

The various embodiments of the invention and the Methods for preparing the stable suspensions according to the invention are illustrated in the examples below.

309838/1179

example 1

The above-mentioned carboxypolymethylene polymer "Carbopol 941" is added to 400 ml of ethylene glycol. After allowing it to soak for a few minutes, 10 ml of a 25% aqueous solution of diisopropanolamine was mixed with the carboxypolymethylene-glycol mixture, whereby the carboxypolymethylene was neutralized and a thick slime was formed. In another mixer, 150 g of powdered clay "Linde A" (0.3 u) were added as a polishing agent in a further 400 ml
Ethylene glycol dispersed. Twenty drops of a red dye were added for coloring. This alumina dispersion was quickly poured into the previously prepared carboxypolymethylene slime in the first mixer and mixed well with the slime. A stable rose-colored suspension of the clay powder "Linde A" in ethylene glycol was obtained. The suspension had the following composition:

Ethylene glycol 84.6% by weight

Powder 14.3 "

Carboxypolymethylene o, l ""

25% aqueous solution of

1 ο ""
Diisopropanolamine '

Example 2

The suspension was prepared in the manner described in Example 1, but using 150 g of clay powder
"Linde C" (l, ou) was used as a polishing powder in place of the alumina powder "Linde A" and a yellow dye was used in place of the red dye. A stable yellow suspension of the alumina powder was obtained.

309838/1179

- 6 - -

Example 3

1.0 g of carboxypolymethylene "Carbopol 941" was 400 ml Ethylene glycol mixed in. After allowing the mixture to be absorbed For a few minutes, Io ml of a 25% strength aqueous solution of diisopropanolamine was added to the mixture of carboxypolymethylene and glycol are added, which neutralizes carboxypolymethylene and forms a thick slime became. 150 g of "Linde A" clay powder were dispersed in 400 ml of water in another mixer. This dispersion 20 drops of red dye were added. That The alumina-water mixture quickly became the carboxypolymethylene mucilage added in the first mixer and mixed well with it. A persistent pink-colored suspension of carboxypolymethylene in a water-glycol mixture as a carrier was obtained. The suspension had the following Composition:

Ethylene glycol 44.1% by weight

Water 4o, o ""

Powder 14.8 ""

Carboxypolymethylene o, l "" 25% aqueous solution of

ι _o H ti

Diisopropanolamine '

Example 4

A suspension was based on that described in Example 3 Manufactured in a manner using, however, an alumina powder "Linde C" and a yellow dye instead of the alumina powder "Linde A" and the red dye were used. One

309838/11 79

Stable yellow suspension of the clay powder "Linde C" was obtained.

Example 5

The experiment described in Example 3 was repeated, but using loo g of "Linde B" clay powder (0.05 u) and one blue dye was used in place of the "Linde A" clay powder and the red dye. A constant one blue suspension of the clay powder "Linde B" was obtained.

Example 6

A suspen: ion was made from the same components and prepared in the same way as in Example 5, however, to neutralize the carboxypolymethylene 4, ο ml a 10% aqueous NaOH solution instead of diisopropanolamine was used.

Example 7

21 g of carboxypolymethylene "Carbopol 941" were in o.95 1 dispersed in deionized water. This non-neutralized slime of the carboxypolymethylene was then with a 1/15 hp mixer model "Eastern 8A" with a propeller 14 cm in diameter rotating at 725 rpm, 7.5 1 ethylene glycol mixed in a 23 1 steel container. In a separate 11.4 liter container was 2.83 grams of powdered alumina "Linde C" dispersed in 7.57 liters of deionized water using a 1/3 PS mixer model Eastern 5VA

309838/1179

_ ρ _mm

a propeller 76 mm in diameter was used. To this mixture, 15 ml of a yellow dye was added. The mixture of ethylene glycol and carboxypolymethylene in the large container was then with 2oo ml Io% aqueous Diisopropanolamine neutralized. The dispersion of the alumina powder "Linde C" was then quickly in the large Given container that contained the mucus. The total mixture was 10 to 15 minutes using the above called mixer "Eastern 8A" mixed.

A permanent yellow suspension of the clay powder "Linde C" in a glycol-water mixture as a carrier was obtained. This example illustrates that the method according to the invention is suitable for large-scale production of the suspensions.

Example 8

A suspension was prepared in the same way and with the same ingredients as in Example 3, wherein however, the abrasive powder "Corundum 160o" was used instead of the alumina powder "Linde A". "Corundum 16oo" is made by Bausch & Lombe and has a medium size Particle size of about Io u It is widely used in the manufacture of eyeglass lenses.

Example 9

A suspension was prepared in the same way and with the same ingredients as in Example 3, wherein

30 9 838/1179

however, the lubricant powder "Corundum looo" (manufacturer Bausch & Lombe) instead of "Linde A" clay powder became. This abrasive has an average particle size of about 18 microns.

Example Io

A suspension was prepared in the same way and with the same ingredients as in Example 3, wherein however, the zirconium oxide of the trade name "TAM Zirox B" as an abrasive instead of the alumina powder "Linde A" was used. This polishing and abrasive agent has a maximum particle size of 5µ and is used for precision polishing used by glasses and minerals.

Example 11

A suspension was prepared in the manner described in Example 3 from the same ingredients with the differentiated that SiC as an abrasive ("Norton No. 32o") Linde A was suspended in place of the alumina powder. This material has an average particle size of 32 µ.

Example 12

A suspension was prepared in the manner described in Example 3 from the same ingredients with the Difference, that B.C the trade name "Norbide Nr.32o" was suspended as an abrasive in place of the "Linde A" clay powder. This abrasive has a medium grade Particle size of 32 u.

Example 13

A suspension was prepared in the manner described in Example 3 from the same ingredients with the

309 838/1179

- Io -

The difference is that spherical alumina with a particle size in the range from 74 to 44 microns instead of the alumina powder "Linde A" was suspended.

Example 14

.Einj & _Su £ Ee ^ jLon_were .in the manner described in_ Example 3 from the same ingredients with the difference / that SiO ₂ ("Kona sand") with a particle size in the range from 74 to 60 and instead of alumina powder "Linde A" is suspended became.

Example 15

A suspension was prepared in the manner described in Example 3 from the same ingredients, wherein however, buffing red was used as a buffing agent instead of "Linde A" alumina powder.

Example 16

A suspension was made from the following ingredients:

1) Mixture of 8oo ml of ethylene glycol with 45o g of alumina powder "Linden C".

2) Dispersion of 2 g of carboxypolymethylene "Carbopol 941" in 250 ml of water, neutralized with a solution of 5 g of diisopropanolamine in 3o ml of water.

Manufacturing process: The ethylene glycol and the alumina powder "Linde, C" turned into a thick in a mixer

3 OS 8 31/1 1 T

Porridge mixed. In another mixer, the water and carboxypolymethylene were mixed and mixed with the diisopropanolamine solution neutralized. The two mixtures were mixed in another mixer. A very thick one, however good suspension was obtained. This suspension had the following composition:

Ethylene glycol 54.64% by weight

Powder 27.7ο ""

Water 17.23 ""

Carboxypolymethylene "Carbopol 941" ο, 12 ""

25% aqueous solution of diiso-

,. o, 3o ""

propanolaium '

This suspension was used on a lapping tool for production, to which a paste is normally applied, which is made by mixing dry alumina powder "Linde C" with about 50% water. It was found that the ethylene glycol suspension achieves an equally good or better material removal than with the standard paste, which contains 50% powder. The lapping tools appeared to stay cooler and there was no need to periodically add water to keep the powder moist.

Example 17

1.0 g of carboxypolymethylene "Carbopol 941" became 400 ml of propylene glycol mixed in. After allowing the mixture to be drawn in for a few minutes, Io ml of a 25% aqueous solution became Solution of diisopropanolamine added to the mixture of carboxypolymethylene and glycol, creating the carboxypolymethylene neutralized and a thick slime formed

3 O 9 8 3 'Λ I 1 1 Ί' "· ί

became. 150 g of "Linde C" clay powder (1, ou) were dispersed in 400 ml of water in another mixer. This 20 drops of yellow dye were added to the dispersion. The clay-water mixture quickly became the carboxypolymethylene slime added in the first mixer and mixed well with it. A persistent yellow suspension of the alumina powder "Linde C" in a carrier mixture of water and polypropylene glycol was obtained.

Example 18

A suspension was prepared in the manner described in Example 17, but using dipropylene glycol instead made from propylene glycol.

Example 19

A suspension was prepared in the manner described in Example 17, but using diethylene glycol instead made from propylene glycol. ·

Example 2o

A suspension was prepared in the manner described in Example 17, but using triethylene glycol instead made from propylene glycol.

Example 21

A suspension was prepared in the manner described in Example 17, but using tetraethylene glycol instead made from propylene glycol.

3/117 «

Example 22

A suspension was prepared in the manner described in Example 17, but using hexylene glycol instead made from propylene glycol.

Example 23

l.o g of carboxypolymethylene "Carbopol 941" became 400 ml of propylene glycol mixed in. After allowing the mixture to be drawn in for a few minutes, Io ml of a 25% aqueous solution became Solution of diisopropanolamine with the mixture of carboxypolymethylene and glycol mixed, thereby neutralizing the carboxypolymethylene and forming a thick slime became. In another mixer, 150 g of "Linde C" alumina polishing powder (l, o u) were added to a further 400 ml of propylene glycol dispersed. Twenty drops of a yellow dye were added for coloring. This alumina dispersion became quick into the carboxypolymethylene slurry previously prepared in the first mixer poured and mixed well with the slime. A persistent yellow suspension of the alumina powder "Linde C" in propylene glycol was obtained.

Examples 1 and 13 illustrate the use of two non-aqueous glycols, namely the lowest molecular weight members of two groups of glycols, the ethylene glycols and propylene glycols. Examples 19 to 21 illustrate the use of higher molecular weight ethylene glycols in a water-glycol mixture. The assumption is justified that the higher molecular weight polyethylene glycols of the formula HO-CH ₃ (CH ₂ -O-CH ₂ ) _n CH ₂ -OH

309833/1179

would form good aqueous and non-aqueous suspensions at higher values of η than those described Values have been tried. This would apply in particular for values from η to 7, i.e. for glycols that are exposed to ambient conditions are still liquid.

Examples 3 to 5 describe the preferred suspensions, according to the invention.

In all the experiments described in the preceding examples, only a small "excess of the Neutralizing agent used so that the suspensions remained in a neutral or slightly alkaline environment with a pH below Io. All neutralizing agents for carboxypolymethylene resins are bases, namely either organic such as diisopropanolamine, which in most examples was used, or inorganic ones, e.g. NaOH in Example 6. As further bases, the carboxypolymethylene resins Neutralize in the ethylene glycol-water system are suitable Ammonium hydroxide, triethanolamine, monoethanolamine, triethylamine and the product under the trade designation "Ethomeen C-25". It was found that diisopropanolamine is the most effective neutralization system in the systems of the present invention, so it is preferred as the neutralization agent. The suspensions made using this preferred organic base are prepared, have the advantage that no inorganic ions, e.g. Well, are present to some extent. Ions such as sodium are very detrimental to polished semiconductor substrates.

0 9 8 3 8/1179

For certain applications, however, a high or a low pH value or an ionic system is advantageous. the Properties of the carboxypolymethylene suspension are not impaired over a pH range of 3 to 12, however, the adjustment of the pH and the addition of inorganic additives must take place after the carboxypolymethylene has been completely neutralized with the neutralizing agent.

The carboxypolymethylene resin "Carbopol 941" is used in the invention Suspensions are preferred over the other carboxypolymethylene resins because of their relatively low viscosities able to train in ionic systems. The other carboxypolymethylene resins "Carbopol" are used to form much thicker emulsions and suspensions.

The uses of these clay suspensions are similar as versatile as the powders from which they are made. They can be used for virtually any polishing job be, in which alumina powder were previously used, but they have the new advantage that they are easier to handle than the corresponding powders. Since they are viscous, they stay up longer the lapping tools as similar aqueous slurries, and they are much less subject to drying out on the lapping tool. Since they are chemically neutral, they have an effect no corrosion of the lapping tools as is the case with some other commercial products.

3 0 9 8 i -i /

Claims (6)

Claims 1. Polishing agent, consisting essentially of a powdery Abrasive and polishing agent that is used in non-agglomerated State has a particle size of about o, ol to 75 u and is suspended in a carrier substance, which essentially consist of a glycol thickened with a neutralized carboxypolymethylene polymer consists. 2. polishing agent according to claim 1, characterized in that that the carrier substance consists essentially of ethylene glycol and up to 5o wt.% Water, which is neutralized with a Carboxypolymethylene polymer is thickened, consists. 3. polishing agent according to claim 1 and 2, characterized in that the carboxypolymethylene polymer with a inorganic or organic basic material selected from ammonium hydroxide, sodium hydroxide and organic Amines existing class is neutralized 4. Polishing agent, consisting essentially of alumina powder, which in the non-agglomerated state has a medium Particle size of o, o5 to l, o u has and is suspended in a carrier substance which consists essentially of Ethylene glycol and up to 5o wt.%, Water that with a neutralized carboxypolymethylene polymer is thickened. 3 0 9 8 3 8/1179 Strength 5. Stable polish suspension consisting essentially of about 84.6 wt.% Ethylene glycol, about 14, 3 wt.% Alumina as Polierpülver, such as o, l wt.% High molecular weight Pοlymethylenpolymerisat and about l, o wt.% Of a 25% aqueous diisopropanolamine solution. 6. Resistant polishing agent suspension, consisting essentially from about 44.1% by weight of ethylene glycol, 40% by weight of water, 14.8% by weight of alumina powder, about 0.12 % By weight of carboxypolymethylene polymer and about 12% by weight of a 25% strength aqueous diisopropanolamine solution. 309838/1179