DE1924357A1 - Process for the production of a thixotropic, resinous mass and a suitable thickener - Google Patents

Description

There is currently a great need for substances that increase the viscosity of paints, emulsions, molding compounds and other resinous products. Next to the thixotropic product obtained must possess several other properties, in particular in order to achieve the desired thickening good flowability, good spreadability, low tendency to drip or flow, good transparency, low tendency to dry out and good wetting ability.

Both chrysotile asbestos and finely divided silica are each known on their own as thixotropic thickeners. The manufacture of a thickener from these two substances, however, would require considerable effort. Some types of asbestos that can cause thickening Resin-containing masses are very suitable, lead to the formation of agglomerates When using the most effective Asbestetoff® form in the uncured resin

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large lumps with diameters of 1 one and more. It it goes without saying that a product with such undesirable properties is economically unusable is.

It has now surprisingly been found that a thixotropic thickener containing chrysotile asbestos can be obtained if the ratio of asbestos to finely divided silica is set precisely. The selection of a certain Aebest fiber length for the production of the thickener is also beneficial. In addition, under certain circumstances the use of a dispersing device, for example an ultrasonic agitator instead of a conventional agitator, helps to overcome the problems associated with the tendency to agglomerate.

The subject of the invention is a process for the extraction of a thixotropic resinous mass-3, which is characterized in that a thickener is added to the hardy mass, which contains an intimate mixture of finely divided chrysotile asbestos fibers and silica with an average particle size of 2 to 10% ₅ where the ki es el acid level is 5 to 95% by weight of the mixture.

Although the best thickening is achieved when the mixture contains around 75 % asbestos (see Table 2 below), the best results overall are obtained when the asbestos content is 15 to 25 % (see Tables 4 and 5 below ).

The preferred method of making the finely divided Chrysotile asbestos fibers and the intimate mixture of finely divided Chrysotile asbestos and finely divided silica

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BAb ORIGINAL

is that you have an asbestos / silicic acid emisehung Milled in a jet mill · This process excels is characterized by the fact that you have a moving mass of finely divided Asbestos and silica suspended in a gaseous medium at superatmospheric pressure and at temperatures between room temperature and 1093 ° C. it is continuously within the specified range Temperature range further fluid in one A plurality of streams of high viscosity is introduced which are directed into the interior of the mass, so that in the same an extremely high turbulence occurs, through which the suspended particles are ground and broken, at the same time, the shredded asbestos fibers and silica particles continuously come together from the mass be discharged with the gaseous medium, whereupon the finely divided asbestos fibers and the silica from the suspending gas are separated. The preferred oases for suspending the particles are air and Steam. The most suitable devices for the crushing of the asbestos and the silica are thus Jet mills. These mills have been known per se for a long time and are known under the names Micronizer, Micronmaster, MaJac, Qetomizer etc. on the market.

The preferred jet mill is the "Micronizer" in which relatively coarse particles are suspended in a gaseous medium and in a closed space be whirled up, further gas is introduced into the vortex mass so that in the mass the required Turbulence for crushing and breaking up the particles is created.

The length of the asbestos fibers is determined by the jet mill treatment of chrysotile asbestos. In this way the short pas are obtained, which for the invention

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straight procedures are most beneficial. The biggest Part of the fibers is 5 to 10 mm long.

The first step in the production of the thickener according to the invention is the selection of the raw materials. It has been found that chrysotile asbestos fibers are particularly suitable for this purpose. This material is commercially available (Plastibest 20 from Pa. John Mansville Corporation). Chrysotile asbestos is a water-containing magnesium silicate, the chemical composition of which can be represented _{by the formula 2MgO.2SiOg.2H 2 O.} The approximate chemical analysis of this material is given in the table below.

Table I. NOK oo. ? % MgO 40-42 % K ₂ O 0-0.2 % SiO ₂ 38-42 % Na ₂ O 0-0.2 % H ₂ O 12-15 % P ₂ O ₅ 0-0.1 % FeO Trace-6 % Cr ₂ O, 0-0.1 % Al ₂ O, 0-0.3 %

The material has a specific gravity of 2.5 to 2.6.

The other raw material is finely divided silica, which is commercially available under various brands
(e.g. Cab-o-sll, Syloid and Hisil). The commercial product referred to as "HisII 223" gives particularly satisfactory results. This is a precipitated one

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water-containing silica with a very small particle size. The main features of this product are summarized in Table II.

Table II

SiO CaO

NaCl

Weight loss at 105 ^° C. OlUhverlust at 1200 ⁰ C

pH of a 5 aqueous solution

specific oewioht in rubber

Particle size limit

colour

Refractive index

oil absorption (Gardner-Sward)

surface

89.2 % 0.6 % 0.7 % 1-5 ^

5.2 $

9.3 * 6.5-7.3

2.0

0.022 αϊ white 1.46 125-165 g oil / l00 g

140-160 m ² / g

Although the intimate mixture of asbestos and silica for some Anwendungszweoke 95 to 5 wt.% Asbestos and, correspondingly, 5 finely divided to 95 £ silica may contain, was found "that from the standpoint of storage stability, flow properties and abglichst low tendency to Eintrooknen the best can be obtained

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can if the asbestos content is around 15 to 25 % . When working in this area, the above-mentioned tendency to agglomeration is practically completely suppressed.

Either air or steam can be used as the gaseous medium when grinding in the jet mill, but grinding with steam is preferred. The mill is operated at a temperature below 1O9J5 ° C, preferably at a temperature of 260-982 ⁰ C.

The thickener is the resinous mass Im generally in amounts of about 0.5 to 2 parts of thickener per 100 parts of resin, preferably of about 0.6 to 0.8 parts of thickener added per 100 parts of resin.

The invention thus further provides a thickener for resinous compositions, consisting of an intimate mixture of finely divided chrysotile asbestos fibers with a length in the range from 5 to 10 mm and silica with a particle size of 2 to 10 / U, the silica content of the thickener being 75 to 85 $> and the asbestos fibers make up 100% of the rest.

The thickener according to the invention can be used for thixotropic thickening of plastisols, organosols, synthetic and natural resins, latices, paints, liquid polyesters, liquid polyepoxides and other substances are used.

The following are intended to explain the invention in more detail Examples serve.

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example 1

A number of attempts have been made in order to show what different results are obtained when using different types of silica as raw material.

Asbestos ("Plastibest 20") was subjected to a jet mill treatment in steam together with amorphous silica from five different sources at three different mixing ratios of asbestos to silica. Grinding was carried out at a Dampfeiniaßtemperatur 399-454 ⁰ C and at a pressure of J>, 52 to 10.5 ATU. The product properties were determined on the basis of its use as a thixotropic agent for an epoxy resin system. The viscosity measurements were carried out using a commercially available epoxy resin using a Brookfield LVT viscometer at 6 revolutions per minute with a No. 4 rotary spindle. The content of the thixotropic thickener was 1 part per 100 parts. The results obtained are summarized in the table below.

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Table III Viscosity in oP

Type of SlO ₀ 250 Asbestos 5 <# Asbestos Kiesel- Oehllt 75 # Kiesel- 50 * Silicic acid in % acid

asbestos

Pebble-

acid

Pebble-

acid hydro

gel 30> 000

Silicic acid

dry gel 70 2 000

spray-dried silica gel 90 11 800

fine-grained

Silica 95 8 400

fine-grained

Silica 96 8 000

14th 000 21 600 12th 400 27 200 16 000 25th 400 16 800 25th 400 14th 800 23 200

When the asbestos was used in the absence of silica, the product had a viscosity of 20,800 cF. It is clear from the results that the best results are achieved when the thickener contains 75 % asbestos and 25% finely divided silica.

Example 2 Another important property of the claimed

is the shelf life of the thickened products. tuck determined in a series of experiments in which the Viskositl

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and the Oellerzeit were determined immediately after the addition of the thixotropic agent, and again after one week of aging of the product at 37.8 ⁰ C. The resin alone was used as a comparison for determining the effectiveness of the various additives. For example, it is clear that the oiling time of the product must largely correspond to the oiling time of the resin itself if the product used is to have any value as a thickening agent.

In this series of tests, the thickener was fed to the mill at a rate of 100 to 300 g per minute. The mill was operated atmospheres with an inlet temperature of 438-495 ° C, an outlet temperature 210-349 ⁰ C and at a Druok of 3 * 52nd The viscosities were determined in the same manner as in Example 1. The gelation tent was determined by observing the time required for the samples to gel when exposed to air. The results obtained in this series of tests are summarized in Table IV.

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Table IV

Try to collect no. settlement

Properties at the beginning of the experiment

Viscosity in oP

at 6 rpm 60 rpm oil

time in minutes after aging for one week at 37.8 ⁰

viscosity

in cP

at 6 rpm

Thickener · Gel ler concentrate tent in parts each Minutes 100 parts

O O 9 ί 1 5OJi asbestos 1 800 uv
co
NJ 50Jt pebbles
acid ehydrogel CO 2 5QJi asbestos 2 000 O
tr « 5056 pebble
acid hydrogel 3 2556 asbestos 2 400 75 / S single-part
Silica 4th 25Ji asbestos 2 400 75 individual parts
Silica 5 Resin alone 600 6th part-part
Silica
alone 2 000

820

800

940

940

320

I 600

1,800

2,800
2,700

200

2,300

180+

157

X08

75

83 91

1.1

0.6

0.75

O.65

CD NJ ■ P- » GJ

It is clear from the results that the best results are obtained by using a mixture of 25 % asbestos and 75 % fine silica. A considerable improvement in the viscosity and shelf life of the product is achieved. The use of a mixture of 50 % asbestos and 50 % silicic acid hydrogel leads to a product whose gel time is increased almost by a factor of 2 at a concentration of 0.6 parts per 100 parts.

Example 3

Another important test is to determine the tendency of polyester resins to flow out of a laminate. For this purpose, a standard investigation method has been developed by the industry, with the help of which the leakage properties of a thickened resin can be determined. As the resin worked into the glass cloth we-r ^ Qj. emB _d k rmte this a removal effect desthixotrop® ^ d @ r Verdickungewirkung drove the additive.

The test is conducted at a temperature of 4-0 ⁰ C using 70 g of the carried out under investigation thickened resin laminate · In this test there are two layers of a mat .and a layer of fabric usage. A layer of the two mats is placed on a 23 x 23 cm glass plate, after which approximately 36 g of the thickened resin mass are worked into the mat using a spatula. The second mat is placed on top of the first mat and 19 g of the resfcli @ fe <m resin are poured over the layer and a spatula is carefully worked into the glass. AnSChIIeS ^ ¹ S the Sshiehfc will be launched from Tuen on the laminate and 5 υ ώ @ ® Her SE® be on the cloth

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poured, again using the spatula, to process the laminate.

The glass plate with the complete layer structure is inclined by 70 ° and placed over a balanced container in which all resin flowing out of the laminate is collected. The amount of resin that has leaked into the container is determined by weighing after 30 minutes and the percentage of resin that has leaked is calculated using the following formula!

Weight of resin collected
χ 100 = run-out in

Weight of resin used in the test

According to the standard values of the industry, the maximum value for the run-out that can still be accepted is 2 #. The results obtained using this test on the products of the present invention are as follows Table V compiled.

Table V

Experiment total concentration viscose outlet no. Setting in parts per act in cP in ^

100 parts at 6 rpm

5J asbestos 0.48 2 000 4.7

50 * silica hydrogel

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Port set table V

Try together no. settlement

Concentration in parts 100 parts each

Viscosity in cP at 6 rpm

Run-out in %

2 25 # asbestos 0.55 75 # silica hydrogel

25% asbestos 1.0 75% silica hydrogel

25% asbestos 0.95 75% finely divided silica

2,000

.800

2,000

4.0

1.2

0.7

The material used for Experiment 4 was of reduced effectiveness because of the shorter length of the asbestos fibers. However, the leakage properties were improved over the material of Experiment 2 , which was a more effective thickener. In experiment 3, the fiber length was reduced somewhat, as a result of which the run-out properties were improved with a simultaneous partial loss of the thickening effectiveness.

Example 4

The novel thickeners are not only useful as thickeners for resins but also have other uses. One of these uses is the thickening of epoxy adhesive for Packaging purposes · The thickener according to the invention

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was made with bentonite lind fine silicas in the Standard Penetration Test and Standard Test for Overlap Vision Strength compared. The one with this The results obtained from the test series are summarized in the following table VI.

Table VI

Try together no. settlement

Concentration Durohdrinin parts depending on supply
Parts. (ASTMD 217- 60T)

Overlap shear strength in kg / cm ²

Bentonite

25th

75 # asbestos 25jg f one-piece silica

115
118

50.6 92.3

5 # asbestos 3.25 $ 50 finely divided Silica

119

93.8

It is clear from the results that both of the compositions tested are superior to the commercial ones that contain bentonite as a thickener for the adhesive

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Claims (1)

Claims ! • / Process for producing a thixotropic resinous Mass, characterized in that one of the resinous Mass adds a thickener, which is an intimate mixture of finely divided chrysotile asbestos fibers and Contains silica with an average particle size of 2 to 10 VU, the silica content 5 to 95 percent by weight of the mixture. 2. The method according to claim 1, characterized in that a thickener is used in which the silica content is about 75 to 85 % and the The rest is 100 % «ΐώ 2hi? Yso til asbestos. j5. Method according to claim 5 or 2, characterized in that » that the thickener mixture in an amount of 0.2 to 0.8 parts by weight of thickener added per 100 parts by weight of resin. 4. The method according to claim 1, 2 or 3 »characterized in that that the mixture has previously been subjected to an ultrasound treatment or a fluid jet for dispersion suspends. 5. The method according to claim 4, characterized in that the thickener by grinding the Produces asbestos / silicic acid mixture in a jet mill. 6. The method according to claim 1 to 5 » characterized in that the pasers have a length in the range of 009832/1905 Own 5 to 10 am. Thickener for resinous masses, characterized in that it contains an intimate mixture of finely divided chrysotile asbestos fibers with a length in the range of 5 to 10 mm and silica with a particle size of 2 to 10 μ , the silica making up 75 to 85 # of the thickener and the Remainder consists of asbestos ugsiwy 0 09832/1905