DE2132619A1 - Process for the treatment of silica - Google Patents

Description

DR. BERG DIPL.-ING. STAPF 2132519

PATENTANWÄLTE 8 MÜNCHEN 8O, MAUERKIRCHERSTR.

• Dr. Berg Dipl.-Ing. Stopf, 8 Munich 80, Mauerkircherstraße 45

Your reference your letter Our reference date J Q, J (Jr) J 197!

Attorney file 21 243

Be / Be

Monsanto Company Stolouis / U.SoA.

"Process for the treatment of silicon dioxide"

This invention relates to a method of improvement the matting properties of synthetic, powdery, amorphous silicon dioxides

The commercially available amorphous forms of silicon dioxide, which are used as matting agents for paints, varnishes and 3-21-3065 -2-

109882/1741 BADORLGiNAL

the like are used generally have good
Matting effects on and remain transparent if they are mixed into a film in small amounts «. Furthermore, if they form a sediment in stored, liquid coatings, they can be quickly and easily redispersed. However, extensive processes and considerable costs are generally required to produce these matting agents. On the other hand, other well-known types of amorphous synthetic powdered silica having an average particle diameter of from about 1 to about 40 µm and other properties mentioned below have not heretofore been used as matting agents for various reasons. Thus, the silicas do not sufficiently reduce the gloss and do not sufficiently form them
smooth coating. " Similarly, when stored in liquid coatings, some silicas form hard, gummy cakes that are difficult to redisperse. It would be very beneficial if these silicas could be used as matting agents because they are generally much cheaper
and require less machining for their production »

Accordingly, a process that converts or improves the matting ability of the above-mentioned types of synthetic, amorphous, powdered silicas would represent an advance on the state of the art.

109882/1741

BATH ORIGINAL

According to this invention, the Mattierungseigensoliaften a synthetic amorphous silica powder with the indicated below properties are improved in that one burns silica at a temperature of about 300 to 75O ⁰ C for a time sufficient to enhance the matting. Synthetic, powdery, amorphous silicon dioxides which have been treated according to the present invention sufficiently reduce the gloss of the materials intended for matting. They can still be easily resuspended if they form a sediment in the coating liquid.

In accordance with this invention, synthetic, powdered, amorphous silicas having the following physical properties can be converted into matting agents or agents with improved matting ability: (1) an average particle diameter of about 0.5 to about 40 y., (2) a surface area of about ^ to 600 m ² / g, (3) a bulk density of about 0.016 to about 0.48 g / com (1 to 30 pounds / cubic foot), and (4) a linseed oil absorption of about 100 to about 400 kg per 100 kg of silica . Examples of such silicas include the commercially available silica aerogels, xerogels, precipitated silicas, arc silicas, and fumed silicas. Further examples of powdered, amorphous silicon dioxides can be found at Her "Colloid Chemistry of Silica and Silicates",

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109882/1741

213261?

Cornell University Press (Hew York) 1955 "Chapter 6, extracted referred to here * It should be noted that. all, above mentioned silicon di " oxides are ground to the desired particle size beforehand by generally "known processes" before firing will. The surface area was determined by the Sears method "described in Anal. Chem., 28, 1981 (1956)"

Uach this invention, the above-mentioned synthetic fine Siliciuradioxidpulver at a temperature of about 300 to 75O ⁰ ung'efähr G, preferably sufficiently burned of approximately 450 kis about 65O ⁰ C for long Verbesstrung their matting ·

The property to a satisfactory "Improvement of matting s in a process according to this invention required firing _s depends on a number of factors, including the temperature and the particular, used in each case, powdery amorphous silica In general, the silica must in most pollen. for at least 10 seconds, or the matting properties are not improved. An upper limit for heating the silica is not set unless determined for practical and cost reasons. For example, the matting ability is improved when silica is β hours heated

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will. A preferred heating time is in the range of about 1 minute to about 60 minutes «

The pressure at which heating is carried out can be varied widely as long as that used Pressure is not so low that evaporation of the raw materials can be followed. Appropriate machining methods can be used at pressures of about 0.5 to 10 atm, the preferred pressure in the range of about 1 up to 4 atm.

Any suitable apparatus for burning the silica of this invention can be used, for example a furnace, kiln, or continuous hot fluidized bed system.

The silicon dioxides obtained after the above-mentioned burning treatment can be used as matting agents in coating preparations be used. In general, the amount of finely divided silica used can be substantial vary, depending on the particular film-forming solid used, the amount of organic solvent and the desired degree of matting. Generally, however, an amount of less than about 0.25 to about 3OfS of finely divided, amorphous, fine silicon dioxide powders, based on the weight of the film-forming pesticide used in the coating preparation

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Examples of coating preparations include drying oleoresin varnishes, such as the unsaturated fatty oleoresin varnishes, including natural resin-unsaturated-fatty oil varnishes and synthetic resin-unsaturated-fatty oil or alkyd varnishes. Other preparations include coating materials of the varnish type, such as cellulose acetate acetone varnish, maleic resin varnish, nitro-cellulose varnish, polyvinyl chloride and Vinyl chloride vinyl acetate copolymer paint eo

The treated, finely divided, amorphous silica powders can be used in the coating preparations by conventional methods (that is, by grinding or simply Mixing) incorporated or dispersed.

The following examples serve to further illustrate the invention. Refer to all parts and percentages ^ refer to the weight, unless otherwise stated »

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example 1

A 10 g sample of the following commercially available silica airgel is heated in a suitable vessel at a temperature of 500 ⁰ C for 60 minutes.

Sample A

Average particle diameter 8 u surface 242 m ² / g

Bulk density 0.09612 g / ccm

(6 lbs / ouoft.)

Linseed oil absorption 2.9 kg oil / kg Sili

cium dioxide

A 1.25 g sample of this airgel is placed in a "Waring" mixer, which is a varnish of the following composition contains j (varnish 90 g)

1/2 sec. Nitrocellulose 5.74

1/4 sec. Nitrocellulose 1.05

Coconut oil modified alkyd resin

(on a dry solids basis) 12.31

Phthalate plasticizers 2.70

Ethyl alcohol 3.79

Naphtha (aliphatic) 6.06

Isopropanol (99 #) 1.60

n-butyl alcohol 6.20

n-butyl acetate 14 »42

Ethyl acetate 11.23

Toluene 34.90

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109682/1741

non-volatile constituents 21.89ε viscosity, cps, at 25 ⁰ O 85

This mixture was "dispersed at 110 volts for 1 minute at slow speed and for 1 1/2 minutes at high speed. 70 g of this dispersion and another 70 g of paint are poured into an approximately 250 g (8 oz) container so that the Mattierungslack obtained 3 wt _o $ flatting agent, based on the thus attainable dry film containing, a 0.152 11m (Ο, Οοβ inch) thick wet coating is applied to a smooth, glossy, warm glass plate. it is allowed that! evaporate the solvent and obtain a smooth, clear, however, matt coating. the sample obtained, closed is allowed to at least 40 days aging. Mach this time has settled the airgel in a bulky, soft sediment which is easily re-dispersible and an equivalent coating w tung, such as those from the freshly produced paint.

The above procedure was carried out with the silica airgel of Samples A and. two other commercially available aerogels with the following properties:

B C

DurohsohnittpartikeldurohmesBer - μ 5 2 Surface - m ² / g 161 310

Sohüttdiahte - g / ccm

Ibs / cu.ft.

Linseed oil absorption kg oil / kg silicon dioxide

1098A2 / 17A1

i \ JW SJ fj ί f I / Cf I

0, 08Dl 0 0, 0480 5 3 2, 2 3, 5 ■ 9-

- Q _

In addition were paints using unfired aerogels as a control, _O. The loss of reflectivity or matting, which is indicated in the following Table I, was prepared by reflection of light, using a "Gardner multi-angle G-loss meter", using the light reflection Photoelectrically measured, the reflection was measured at a light angle of 60 °. The fineness given in Table I was given as the "Hegman" fineness. In addition to the sediment height, the aging is also given in Table I. The paint height in the sediment test was 6.9 cm. The sediment resuspension shocks are reported in Table I as the number of end-to-end shocks (90 °).

Table I.
# Alt.test in a 225 g bottle

Sample Heat Treated Upper "Heg Height" Number of

⁰ C flä- man "60 ° of the impact to the

fine-shine Sedineut.Suspen-

m / g means days mentation

A none 242 5 23 210 9.5 mm 3 good

A 1 hour at 700 ° 289 4 1/2 16 210 9.5 mm 3 good

B none 161 7 56 210 9.5 mm 3 good

B 1 hour bo700 ° 182 6 I / 4 22 210 19 mm 2 good

C none 310 5 3/4 45 210 25 mm 2 good

0 1 hour at 700 ° 324 5 1/2 16 210 25 mm 2 good

* Determined according to the "Sears" method. It can be seen from the table that the matting properties of the heat-treated aerogels were improved.

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Example 2

Example 1 above was repeated except that a 10 g sample of commercially available precipitated Silica having the following properties was used in place of the 10 g sample of silica airgel o

Sample A

Burchschno particle diameter 9 u surface 406 m ² / g

Bulk density 0.12816 g / ccm

(8 lbs / cu.fto)

Linseed oil absorption 3.0 kg oil / kg silicone

cium dioxide

The above procedure was repeated for the precipitated silica sample A except that this sample was only Was stored for 60 days and two other commercially available precipitated silicas were mixed with the uses the following properties:

BG

Durchsohn.Particle diameter - γ. 4 7 surface area - m ² / g 269 488

Bulk density - g / cc 0.009612 0.11214

(lbs / cuofto) 6 7

Linseed oil absorption - kg oil / kg silica 2.4 2.2

Sample C was only stored for 60 days. Farther Paints made using unfired, precipitated silica served as controls. The results are given in Table II.

109882/1741

Table II Aging test in 22j5 g bottle

Sample heat treated Qber- "Heg- Lack- Sedi- number d.

Oq flä- man "- 60 height-ment joints z.er-

che pein- shine (mm) height neut.Sus-

17g hext days (mm) pending

A none 406 5 31 60 69.8 1.5 > 100 little

A 1 hour at 700 ° 376 5 1/2 26 60 69.8 6.5 3 good

B none 269 6 21 210 69.8 1.5 30 very little

B 1 hour, 700 ° 307 6 20 1/2 210 69.8 6.3 3 good

C none 488 5 1/4 27 1/2 60 76.2 1.5> 100 little

C 30 min. At 700 ° - 5 1/2 27 60 76.2 6.3 3 good

From the table above it can be seen that the matting properties of precipitated silica, especially the resuspension properties have been improved.

Example 3

The procedure of Example 1 was repeated except that a 10 gram sample of commercially available double-arc silica * was included the following properties, instead of a 10g sample of the autoclave treated Silioaerogel, was used

Durohsohn average particle diameter 7 u surface 204 m ² / g

Bulk density 0.11214 g / oom

(7 lbs./cuoft.)

Linseed oil absorption 2.5 kg oil / kg silica * Arc quartz -12-

109882/1741

The procedure given above was followed and a lacquer using unfired arc quartz produced, the results are given in Table III,

gabeile III

Aging test in 225s bottle

Sample heat treatment over- '' Heg- lacquer- Sedi- number of

Oq fläv man "- 60 height-ment shocks z" er

. before fine gloss (mm) height neut «sus-

W m / g means days (mm) pending

A. no .bo 700 ° 204 VJl 1/2 37 210 69 ,8th 4, 7th 3 Well A. 1 H 186 4th 1/2 18th 210 69 ,8th 4, 7th 3 Well

From the table above it can be seen that the matting properties can be improved with heat-treated arc quartz.

Example 4

There was repeated the procedure of Example 1 except that a 10 ^ g sample of fumed silica in place, was used by 10 g silica airgel. The fumed silica had the following properties »

average Particle diameter I5 u surface area * 201 m ² / g

Bulk density 0.08010 g / ccm

Linseed oil absorption 2.8 kg oil / kg Sili

cium dioxide

again the experience given above.

103882/1741 "" ¹³ ~

leads. Furthermore, as a control, a paint was produced using pyrogenic, unburnt silicon dioxide The results are summarized in Table IV.

Table IV Aging test in 225 g bottle

Sample heat treatment upper "Heg lacquer Sedi number of

O _n area- 60 height- joints z _o er

before pain shine (mm) height neut. Sus-

mr / g means days (mm) pension

A none 175 3 1/2 33 210 69.8 4.7 3 good A 1 hour bc700 ° - 3 1/2 19 210 69.8 4.7 3 good

It can be seen that the matting properties are improved.

Example 5

The procedure of Example 1 was repeated except that a 10 g sample of pit quartz was used with the following given properties, instead of the 10 g sample of the autoclave treated airgel was used »

average particle diameter 10y. Surface <1 m ² / g

Bulk density 0.801 g / ccm

Linseed oil absorption <0 »5 kg oil / kg Sili

cium dioxide

The procedure given above was again carried out on the G-ruben quartz sample. Another commercially available 1 09882 / mi " ^U "

Available pit quartz had the following properties:

average Particle diameter 8> u surface 2 m ² / g

Bulk density 0.64080 g / ccm

(40 lbs / cuoft.)

linseed oil absorption 0.5 kg oil / kg Sili

cium dioxide

Sample B was only stored for 60 days. It was further paints using unfired pit quartz _o prepared as a control The results are summarized in Table V below.

Table Y

Aging test in 225 g bottle '

Sample heat-treated upper- '! Heg- lacquer- Sedi- number of

o _Q flä- man "- 60 high- ment impacts ζ" renew fine gloss (mm) high suspension m / g days (mm)

A none <1 6 82 210 69.8 1.5> 100 little

A 1 Stdobo700 ° < 1 6 71 210 69.8 1.5> 100 little

B none 2 6 55 60 69.8 1.5> 100 little

B 1 hour _or 700 ° 2 6 55 60 69.8 1.5> 100 little

It can be seen from Table V that the matting properties were not improved by mine quartz.

Example 6

The procedure of Example 1 was repeated except that instead of the laok used in Example 1, another

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- 15 rer with the following composition was used

1/2 sec. Dry nitrocellulose 10 Maleic rosin ester gum 4th Castor oil-modified-glycerol phthalate acid anhydride alkyd resin 6th Butylphthala t 2.5 raw castor oil 2.5 Butyl acetate 11.25 Butyl alcohol 7.5 Ethyl alcohol 11.25 Ethyl acetate 10.0 toluene 37.5 Example 7

The procedure of Example 1 was repeated except that the paint with the following properties, instead of the varnish of Example 1, was used.

Toluene 9.2

Butyl acetate 11.5

Acetone 26.4

Methyl acetate 24.0

Ethylene glycol monomethyl ether 15.6

Methyl phthalyl ethyl glycollate 9.2

Cellulose acetate 4.1

Example 8

A linseed oil modified glycerine phthalic anhydride alkyd resin varnish of medium oil length grading 38 # solids and an acid was used as a drying oil varnish, 59 parts of the above varnish, "/ thinned with

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Parts of medium cut naphthenic hydrocarbon solvent, along with 30 parts of the fumed silica airgel from Sample A, were "mixed" according to the procedure described in Example 1 in a 0.94 liter (1 qt) ball mill at 60 rpm for 14 hours to form a 100 parts of the lacquer were added to the mixture in the ball mill and the resulting mixture was ground for 1 hour at 60 rpm ₀ Another 241 parts of the lacquer were added to the ball mill and the resulting mixture was ground for 1 hour at 60 rpm, whereby a matte finish was obtained.

The silica airgel in the varnish remained fluffy, resulting in a varnish coating that retained its appearance and properties for a very long time. The airgel in the varnish is not deposited in the form of a hard cake, but instead forms voluminous, soft layers which are easy to redisperse by simple stirring _e

Example 9

A phenol type varnish was prepared as follows. 100 g of pure phenol resin, prepared by heating of tert · amylphenol with - formaldehyde refined under alkaline conditions, and 12.5 cc of alkali linseed oil (F 565 ⁰⁾ was heated for 40 minutes at a temperature of 295 ⁰ C and another 90 minutes at this Temperature held. 12.5 ecm "Tongue oil" are then added and the approach to a

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10 9 882/1741

Heated temperature of 273 ° C (525 ⁰ F) and maintained at this temperature Ms it has a viscosity of 3000 cps showed-This batch was then cooled and diluted with Laokbenzin "diluted until 50 $ solids contained. Sufficient amounts of cobalt and Bleinaphthanat were was added to give the diluted batch a content of 0.03 $ cobalt and 0.3 $ lead, based on the metal of the oil base in the batch. 258 g of the paint described above were mixed with 50 com medium-cut naphthenic hydrocarbon solvent diluted · to this mixture, 13 parts of silica airgel, sample B, were prepared as added in example. 1 The resulting mixture was abgemahlen in a 0.94 1-making ball mill, to which was 11 hours required _o in this way a matt paint was obtained after 6 months the silica airgel particles contained in the laok can easily be redispersed by simple stirring.

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Claims (1)

- 18 patent claims: 1 ο Process to improve the matting ability of synthetic, amorphous, powdered silicon dioxide with (a) an average particle diameter of about 0.5 to about 40] i, (b) a surface area of about 40 to about 600 m / g, (c) a bulk density of from about 0.016 to about O »48 g / ccm (ungo 1 to ung, 30 pounds per cubic foot) and (d) a linseed oil absorption of about 100 to about 100 kg per kg of silicon dioxide, characterized in that one burns silica at a temperature of about 300 to about 75O ⁰ C sufficiently long time to improve its matting. 2. The method according to claim 1, characterized in that the temperature is kept in the range of about 450 to about 65O ⁰ C, the silicon dioxide used is a silicon dioxide airgel, a silicon dioxide xerogel, an arc silicon dioxide or a fumed silicon dioxide and that the burning is about 1 minute to about For 60 minutes. 3 · The method according to claim 1, characterized in that the burning at a pressure of 0.5 up to 10 atm w ^ rd. 109882/17 * 41