DE2403899B2 - PROCESS FOR COATING FINE PARTICULAR INORGANIC MATERIAL WITH A POLYMER - Google Patents

Description

A process for coating solid particles with polymers, in which solid particles are placed in water or dispersed in an organic solvent, adding a vinyl monomer and the polymerization of the Monomers in the presence of a water-soluble or oil-soluble polymerization initiator for formation of a polymer on the surface of the solid particles is already known. However, the The surface of glass has a poor affinity for polymers and does not show sufficient affinity Binding effect on polymers. Accordingly, it is extremely difficult to produce glass products with a produce uniform and satisfactorily thick polymer coating by this known method.

Further, as a way of making artificial abrasives, there is a method in which abrasive particles mixed with methyl methacrylate and a polymer thereof and heated the mixture and is compressed in the presence of a peroxide (JA-AS 1667 / Sho. 24), a process in which Abrasive particles and plastic powder together with an unvulked rubber composition are kneaded, after which the kneaded mixture is brought into the desired shape and heated is cured (JA-AS 1897 / Sho. 29), and a method is known in which a mixture of abrasive particles and polymer powders are provided with a monomer which dissolves or swells the polymer can, after which the mixture is heated and pressed (JA-AS 9547 / Sho. 35). These known methods generally take advantage of the adhesion of polymers to bond abrasive particles. However wise these methods have some disadvantages; so is the bond strength between the abrasive particles and the polymers are low, the strength of the abrasive is low and there is a tendency to local agglomeration of abrasive particles in the polymer so that products of the desired uniform quality are not can be obtained.

As gravel sand, casting sand or molding sand, for example, sand particles are those with a partial reaction product are covered by phenolic resin and hexamethylenetetramine and sand particles are known to stand on their Surface have a coating layer of a resin, which by temporarily melting a resin powder was formed on the surface of the sand particles. With these sand particles that come with a When polymers are coated, the coating of the polymer adheres to the surface of the sand particles only through physical binding forces. Accordingly, such coatings tend to peel off during transport or storage. Furthermore, the production of the coated sand particles requires heating and cooling measures, so that the cost of the devices and the processes are higher become complicated and disadvantageous. On the other hand, the use is a relatively large amount

ίο of the polymer for the complete binding of the individual Sand particles required. However, molds made by pouring sand with such a large size develop Amount of polymer produced, inevitably gases and lead to deformation or destruction,

is when, for example, a molten metal enters the Mold is poured.

From US-PS 34 48 073 a process is known in which vinyl monomers in the presence of free Free radical generating compounds such as peroxides, persulfate, perborates and percarbonates, etc., and one Accelerator to be polymerized. These accelerators can be materials which sulfur dioxide is adsorbed on adsorbents, for example on zeolites. So it has to be a free one Free radical-forming catalyst and an accelerator are worked. In doing so, however, unsatisfactorily, not all of the polymer on solid particles present in the polymerization system as a cover.

GB-PS 10 25 694 discloses a method for coating a finely divided inorganic material known in which, for example, acrylates as vinyl monomers in the presence of the inorganic material are polymerized. However, this known method cannot be used with a low-viscosity monomer carry out.

From US-PS 20 97 263 it is known vinyl monomers such. B. methyl methacrylate in the presence of Polymerize sulfite ions. However, no suggestions are made how to deal with the polymer coated discrete particles. This also applies to FR-PS 12 73 817, in the vinyl polymers with Sand or glass particles can be described as fillers.

In the invention underlying investigations has been found that when a transition metal or a transition metal compound with a Vinyl monomers in the presence of bisulfite ions is brought into contact, the combination of the

Transition metal or the transition metal compound and the bisulfite ions as a polymerization initiator system acts and a polymer preferably on the surface of the particles of the transition metal or the Transition metal compound is formed, whereby the particles are evenly coated with the polymer will. Furthermore, it was found in the context of the present invention that correspondingly good results can also be obtained using glass particles, abrasive particles and sand particles in place of those Transition metal particles can be used.

The object, the features and the advantages of the invention are explained in more detail below and with the aid of examples.
The term "vinyl monomer" in the present context is intended to denote a compound which can undergo polymerization of the vinyl type in the presence of a radical polymerization initiator.
Examples of such monomers are unsaturated

Carboxylic acids such as acrylic acid and methacrylic acid, their salts and esters, unsaturated nitriles such as Acrylonitrile and methacrylonitrile, halogenated olefins such as vinyl chloride and vinylidene chloride, aliphatic Vinyl esters such as vinyl acetate and vinyl propionate, and aromatic vinyl compounds such as styrene and divinylbenzene.

The expression "substances that can provide bisulfite ion" is intended in the present context Designate substances that can deliver bisulfite ions in an aqueous or alcoholic medium.

Examples of such substances are sulfur dioxide, an aqueous solution of sulfurous acid, bisulfites, such as arrimonium bisulfite and sodium bisulfite, a combination a sulfite such as sodium sulfite or potassium sulfite with a mineral acid such as sulfuric acid.

In a preferred embodiment of the invention solid particles are selected from the group of glass particles, abrasive particles and sand particles in suspended in an aqueous or alcoholic medium, after which a vinyl monomer and a substance the bisulfite ions can provide, are added to the medium and the mixture is continuously stirred, until the polymerization of the monomer is sufficient to coat the solid particles with the resulting polymer expires In this case, there are no special restrictions on the Order of addition of the individual components. The tested particles can become a reaction medium which already contains a vinyl monomer and a substance capable of bisulfite ion can be added.

In addition to normal glass, potash glass, lead glass and other special glasses can be used as a glass component according to the Invention can be used. These glass components can be in the form of powders, granules and pearls are present. Natural abrasive particles such as corundum, emery, garnet, Triple and diamond, and artificial abrasive particles such as silicon carbide, boron carbide, tungsten carbide and artificial diamond, suitable As the sand particles, silica sand, chromite sand, zircon sand and Forsterite sand are cited. These solid particles preferably have a particle size of 10 to 300 mesh.

The vinyl monomer is used in an amount of 1 to 100 parts by weight per 100 parts by weight of the solid particles used. If the product is to be used as a material for abrasives or molding sand, the vinyl monomer is preferably used in an amount of from 1 to 10 parts by weight per 100 parts by weight of the solid Particles used. The substance that can provide bisulfite ion is used in an amount of 0.01 to 15 Parts by weight (sulfur dioxide basis) used per 100 parts by weight of the vinyl monomer

The polymerization reaction according to the invention is only initiated when glass particles, abrasive particles or sand particles coexist with sulfite ions. Omitting either of these above specified two components does not lead to initiation of the polymerization reaction. It was found that the presence of oxygen promotes the polymerization reaction

The reaction product obtained by such polymerization is subjected to filtration Separation of the solid is subjected, which is then washed with water and used to produce the final product is dried. The resulting solid substances coated with the polymer retain the polymer when with an organic solvent such as benzene for 20 hours or more is extracted. It is therefore believed that the polymer is on the surface of the solid substances s is graft-polymerized. As a result of this graft polymerization, the resulting solid substances exhibit the significant advantage that they have a strong binding force even with a low polymer content demonstrate.

ίο The abrasive particles coated with the polymer, which are obtained by the process according to the invention can be used for the manufacture of abrasives be used by placing the particles in heat and under pressure to rods, plates or other suitable shapes can be processed. In this case, the abrasive particles with a smaller content of applied polymer, e.g. B. with a polymer content of 20% by volume or less, in a state of molding in which they are in a thermoplastic or thermosetting Resin are dispersed. Since the abrasive particles coated with the polymer extremely tolerated well with the polymer compared to untreated abrasive particles, those with the Polymer-coated particles are homogeneously dispersed in the resin.

The heating temperature during molding varies depending on the type of monomer used, but is generally in the range from 100 to 250 ^° C. The pressure during molding is in the range from 150 to 450 kg / cm ² , but higher pressures can be selected if necessary .

Sand particles coated with the polymer can be used as molding sand, which has good moldability and has strong bonding ability.

The glass particles coated with the polymer obtained by the method according to the invention are suitable as the molding material and filler. In particular, those coated with the polymer Heat-compression molded glass beads to make reflectors.

The invention thus relates to a method for coating the surface of solid particles with a Polymers in which solid particles are selected from the group consisting of glass particles, abrasive particles and sand particles a vinyl monomer in the presence of bisulfite ions.

The invention is explained in more detail below by means of examples.

example 1

It was fitted a 500 ml three-necked glass flask equipped with a stirrer and immersed in a constant temperature bath which was maintained at 50 ⁰ C.

380 g of water and 100.0 g of 200 mesh glass beads were placed in the flask. To this mixture were 20.0 g of methyl methacrylate and 20.0 ml of a 2 η-aqueous solution of sulphurous Acid given; the whole was left to stand with stirring for three hours. After completing the Reaction, stirring was stopped and the reaction mixture was examined. It was determined, that the polymer and the glass beads were not present separately from one another, but a common one formed a uniform slurry. This product was separated by filtration; the solid became washed with water and then under reduced pressure to produce 116.0 g of dry product

dried, which had a poly (methyl methacrylate) content of 14.0%; this resulted in a polymerization rate of 80%. Microscopic inspection of the product indicated that a uniform and thick coating of poly (methyl methacrylate) had been formed on the surface of each glass bead. This dried product gave molded articles having a flexural strength of 200 kg / cm ² when compression-molded at 180 ° C. for 15 minutes under a pressure of 250 kg / cm ² .

Comparative example

In the same device as in Example 1, 400 g of water and 100.0 g of glass beads with a grain size of 200 mesh were placed. The air in the device was displaced by nitrogen with stirring. To the mixture were added 20.0 g of methyl methacrylate, 0.10 g of potassium persulfate and 0.10 g of sodium bisulfite; the whole was reacted for three hours / ang with stirring in the nitrogen atmosphere. After the completion of the reaction, the stirring of the mixture was stopped and the reaction mixture was examined. It was found that a polymer and the glass beads were separated in an upper layer and a lower layer, respectively. Thus, the surface of the glass beads could not be coated with the polymer in the usual polymerization system using a redox catalyst.

The reaction product was separated by filtration; the solid was washed with water and then dried at 130 ° C under reduced pressure to produce 118.2 g of dry product, which had a poly (methyl methacrylate) content of 15.4%. It was a polymerization rate of 91% determined.

The dried product was mixed thoroughly in a mortar and then compression molded at 180 ⁰ C for 15 minutes under a pressure of 250 kg / cm ^2, whereby moldings having a bending strength of 95 kg / cm ² were obtained.

Example 2

Immersed in a 5-liter four-necked glass flask in a bath of constant temperature of 50 ⁰ C, 3.8 kg of water and 400 g of glass powder (chromium-treated, 50 to 100 mesh) were added. To the mixture were added 60 g of methyl methacrylate and 0.20 kg of a 2N aqueous solution of sulfurous acid, the glass powder being dispersed in the water. The mixture was reacted in air for four hours. When the reaction was complete, the slurried product was filtered off; the solid was washed with water, and then C to produce 445 g of a composition · dried at 130 ⁰ a poly (methyl methacrylate) content of 10.1% possessed; the rate of polymerization was found to be 75%. Microscopic examination of the composition showed that almost all of the glass powder was coated with poly (methyl methacrylate). This product was prepared in the same way as in

Table 1

Example 1 for the production of moldings with a flexural strength of 215 kg / cm ² compression molded.

Example 3

In a 50 ml three-necked flask equipped with a stirrer, 3.00 g of artificial diamond (about 300 mesh), 0.60 g of methyl methacrylate, 0.10 g of methyl acrylate and 20 ml of water were placed. After raising the temperature of the mixture to 6O ⁰ C was added 1.0 ml of a 1 n-wässerigcn solution of sulfurous acid to the mixture with stirring; reacted for four hours at 6O ⁰ C. The reaction product was filtered off; the solid was washed with water and then dried in vacuo at 120 ° C. to produce 3.65 g of solid. Microscopic examination of the solid product revealed that a high molecular weight substance was effectively applied to the surface of the artificial diamond . A molded article obtained by pulverizing the solid product, and compression molding at 19O ⁰ C at a pressure of 200 kg / cm ^2, contained very effectively the polymers and the abrasive particles dispersed therein. Compared to a corresponding abrasive made by polymerizing the monomer with the aid of a conventional radical polymerization initiator such as benzoyl peroxide, said molded article had a strong bonding force between the abrasive particles and the polymer, so that the abrasive particles were hardly removed from the abrasive; even if the particles were removed, a new abrasive surface formed or emerged without scratching the surface of the material being polished. The product is then suitable for perfect polishing.

Example 4

In a 300 ml reaction vessel equipped with a stirrer, 50.0 g of binder particles (180 to 200 mesh) of a group of different binder particles, a predetermined amount of monomer, and 200 ml of water were placed. After raising the temperature of the mixture to 6O ⁰ C for 30 minutes were introduced into the mixture with stirring, 0.60 g of gaseous sulfur dioxide; the mixture was reacted at 60 ° C. for eight hours. The reaction product was filtered off and the solid was washed with water and then ^{dried at 120 °} C. in vacuo to produce a solid product (abrasive particles coated with the polymer). Examination of the product with an electron microscope showed that the polymer coated the abrasive particles very effectively. A molded article obtained by compression molding the product at 200 ^° C. under a pressure of 250 kg / cm ² was tough and was distinguished by its abrasion resistance to commercially available abrasives. Table 1 shows the polymer content and flexural strength of the products using

do various abrasive particles.

Abrasive particles

Used Monnmercs

Polymer content
in the product
(Wt .-%)

Flexural strength
of the molding (kg / cm ² )

Alundum (refractory clay)
carborundum

MMA vinyl chloride 14.2
18.9

409

412

Si'lili-ilunlli'lu 7th 24 03 899 J
8th ltll'J_'l'lL'SllL'kl.'lt
* U "N i ι Il tllkl Hpi'IS
(ki mi) lOrtscl / unu Chromium oxide 365 hobi
No. ■ iklu-n VlTWi ¹ MlIl'U ^- S MullomiTl'S ΙΊιΐΜΐΐιτμι-liiill
1111 I'lllllllk!
((ii-w. ".,) 457 3 I AN 10
| St 10 11.2 301 4th Silica sand I MMA 12
I MA 3 20.9 5 pumice MMA 25 32.5

Remarks:

In the table above, MMA denotes methyl methyl acrylate, MA denotes methyl acrylate, AN denotes acrylonitrile, and St denotes styrene.

Example 5

Using the same apparatus as in Example 4, 50.0 g of alundum, 10.0 g of asbestos powder and 20.0 g of methyl methacrylate were suspended in 400 ml of water. 200 ml of a 1 η aqueous solution of sulfurous acid were added to the mixture; the whole was reacted at 6O ⁰ C for 6 hours with stirring. The reaction product was filtered off and the solid was dried at 120 ° C. in vacuo; 78.2 g of solid product were obtained. Examination of the product with an electron microscope showed that the abrasive particles and asbestos were effectively coated with poly (methyl methacrylate). A molded article obtained by compression molding the solid product at 200 ^° C. and a pressure of 400 kg / cm ² contained the abrasive particles and the asbestos homogeneously dispersed and was distinguished by its toughness and its abrasion resistance to abrasives obtained by conventional methods were obtained.

Example 6

Into a reactor equipped with a stirrer, 10.0 kg of silica sand (No. 6), 0.70 kg of methyl methacrylate, 0.10 kg of methyl acrylic and 40 liters of water were charged. 1.0 kg of an I n aqueous solution of sulphurous acid was added to this mixture at 55 ° C .; the mixture was reacted for 3 hours. The resulting slurry was filtered off, and the solid was washed with water and then dried at 130 "C; 10.72 kg of a solid product having a polymer content of 6.8% were obtained. When the solid product was pulverized and with an electron microscope was examined, it was found that the individual silicon dioxide sand particles were uniformly coated with a plastic malt.

The sand particles thus obtained were press-molded for 5 minutes at a pressure of 150 kg / cm ² (ke for Gießzwck ·) for the manufacture of a casting core at 200 ⁰ C, the high bending strength of 74 kg / cm ^J besiiß. The use of this casting core for casting provided products with better surface properties than the use of an oil. After casting, very good disintegration or very good detachment of the cast core was found.

In the same catfish castings were made from sound particles made that were coated with polystyrene and polyvinyl acetate; this cast iron (each with a Polymer content of 3.5% by weight were used for casting tests The casting cores were easily broken after casting, and the surface of the cast product made a good impression.

Table 2 shows the disintegration of the cast core and the surface properties of the cast products, observed when varying the content of poly (methyl methacrylate). For comparison is also the Strength of the casting cores before casting in Table 2

μ specified.

Table 2 Strength of
Gicßkcrne before
pouring
(kg / cm ') Decay
the
Glass cores surfaces
properties
the cast
Products Polymer-
salary
(0/0) 220
71
35 Well
Well
Well bad
Well
Ulli 10.2
5.1
3.0

Example 7

In a reactor equipped with a stirrer, 10.0 kg of zircon sand (100 to 150 meshes 15%, 150 to 200 meshes 61% and 200 to 300 meshes 24%), 0.60 kg of methyl methacrylate, 0.10 kg N-methylolacrylamide and 40 liters of water. After the mixture was kept at 55 ⁰ C, 500 g of an aqueous solution of 1 ti schwcfcligcr ztigegchen acid; the whole was implemented for 3 hours.

After the completion of the reaction, the resulting slurry was bottled and the solid The mass was washed with water and dried in vacuo at 80 ° C.; 10.61 kg of solid product were also obtained

5 (a polymer content of 5.8% was obtained. This solid product could be easily pulverized , liinc examination of the pulverized product with an electron microscope showed that the individual sand particles were uniformly coated with a plastic material

were coated.

The resulting zircon sandpieces, which are attached to the Methyl methacrylate-N-methylolacrylamide mixed poly mers coated were placed in a metal mold in a thickness of 3 mm below the following

do conditions melt-sprayed:

Plate injection speed 5 kg / Siundc Compressed air pressure 3 kg / cm ^J Air consumption rutc 8 mVhc Low gas consumption approx. 1.2 mVhour

When the cast product was taken out of the metal mold, pecl-baek did not occur,

1tltt RSI / SIP

The product had a flexural strength of 78 kg / cm ² . This shell mold was used for casting to produce products with good surface properties. A very good disintegration of the shell shape was found in comparison with conventional shell shapes based on phenolic resin.

Example 8

80 parts by weight of dry sand, 5 parts by weight of sodium silicate and 2 parts by weight of graphite were used mixed and kneaded well. The mixture was placed in a core mold and while a Solidified carbon dioxide stream. The mixture was then taken out of the mold and placed on top of it The casting core obtained in this way was coated with a dispersion of molding sand (polymer content 20%; production in coated in the same way as in Example 1) in an organic solvent. The composition of this The coating dispersion was as follows:

Components

Parts by weight

Molding sand
Methanol
acetone
Isopropanol

15th
50
15th
20th

The casting core was fixed at 5O ⁰ C and dried to a mold for casting. Firing and Klcbproblcmc tu were in connection with these cast products,

Table J

10

obtained using this form, im In contrast to the use of air-dried molds hardly observed on which a mold coating agent had been applied. This form adsorbs only a very small amount of moisture, if it is kept for a long time.

Comparative Example 2 2.1. Purpose of the comparative example

The following experiments were carried out in order to determine the differences between the invention and that of FIG Ub-PS 20 97 263 to illustrate known teaching.

In particular, the tests were carried out to determine whether the particulate solids that are coated according to the invention, only act as a filler or not.

2.2. Experiments 2.2.1. Test conditions

The tests were in accordance with the erfindungsffcTCon ^Bedin g ^un g ^s and implemented the terms of the US-PS 20 97 263rd

The composition of the starting materials and aie reaction conditions result from following Table 3. For comparison, a polymerization reaction using the same was also carried out Starting materials, as used according to the invention, carried out with the exception that the fine solid was omitted

Composition of the output in the Herial Monomerps Medium

finely divided solid

(G)

(B)

(β) initiator
(S)

invention

Comparison I
Comparison 2 ^J )

Conditions of sale

Reaction. · .- Roiictin temperature duration ("C)

Glass beads MMA 1O ₁ Oi) water 350 NaIISOi- ¹ ) 50.0 1.00

miss """ ""

missing MMAlO ₁ O ') water 350 NaHSO ₁ J) 50

I 00

MMA 10.01) water 175 NuHSO, *) 50 Methanol 175 1.00

(h) 2 2 2

¹ l methyl methylate.

In Example 1, sulfurous silicon is used / um Iv ^ v ₁ .η, η ν,., Ι ι ■

used in all attempts. '' ^{blSStMm Vcr} « ^{lüK: h} ^"«'« r US-PS 20 97 2b3 became judorfi Nu! ISO. in

') Based on Example 9 of US-I ¹ S 20 97 2bJ.

A 500 ml four-necked flask was used as the reaction vessel used, which was provided with a stirrer and a condenser. The reaction was carried out in the reaction vessel performed, which was immersed in a water bath in which there was a thermostat.

2.2.2, Carrying out the experiments In 5 minutes after the start of the reaction, a white cloudy precipitate in the reaction liquid formed in the experiment according to the invention, comparative experiment I and comparative experiment 2, the wellk cloudy precipitate formation of a polymer indicated

After 2 hours, a means of breaking the Reaction added to the reaction system. helmet ? "Um! ^De . ⁿ ^ ^{much wupdo ilcr fcinlcili} « ^c

Renk Si.?. ° ^{dcn the piston! I} deposited! the ifeii / KlS ^en i ^tr , ^{ennlc slch full} «'n <iig in two phases AbAf ·'J" ^{1 Ge} 8 ^hurry! »> ls you« · there was no iJ! ¹¹ U ^Re « ^k 'i ° n system of the comparison vci -

S * ^{1 Ob8l0ich the liquid kclt cloudy and}

2,2,3, results

erh _B i! «. nÄ ^dic , ^{ln d0M cit1Zältlül1} Try I Hr Jüenden S? ¹ "^ *" ^{nbnilplert and} Dried, Die Welse Α " ⁸¹⁰ " ^Su ? ^{stu "ze"} were different AUET

ÄftVÄÄS result ^{sc d} - ^{er rolgcndon}

Table 4 11th 24 03 899 12th Observations
when filtering Weight of the fine
partial solid after
the implementation
(G) Polymer yield ¹ )
( ⁰ M) Polymer content ² )
(0/0) odorless
MMA smell
MMA smell invention
Comparative experiment 1
Comparative experiment 2 58.13
0.18
2.60 81.3
1.8
26.0 14.0
(100)
(100)

') The polymer yield was calculated according to the following equation: Polymer yield (%) = (Wy-W,) - 100 / W ₀ in which W _v the weight of the finely divided solid before the reaction, VV, the weight of the solid after the reaction and Where means the weight of the methyl methacrylate used.

- ') The polymer content was calculated according to the following equation: polymer content (%) = CVVy-W,; - 100 / W,
in which W> and W have the meanings given above.

As can be seen from the table, this is the polymer yield in the experiment according to the invention unexpectedly higher than that of Comparative Tests 1 and 2. This fact clearly shows that the glass beads do not merely represent a filler material, but rather have a beneficial effect on the polymerization reaction exercise yourself.

The polymer, which was prepared according to the polymerization conditions, is in the reaction medium not in the form of discrete particles, but rather in the form of a finely divided solid when the polymerization reaction takes place is completed. If you consider that the finely divided solid according to the invention to the clear Increasing the polymer yield and that the. \> Polymers is incorporated into the finely divided solid, so you can see the differences compared to the invention the prior art of US-PS 20 97 263 clearly recognize.

Comparative example 3
3.1. Purpose of the comparative example

The example was carried out in order to determine the thermal properties of the product according to the invention and of the Product of Comparative Experiment 2 of Comparative Example 2 to be determined.

3.2. try
3.2.1. Test conditions

The thermal properties of each product! were made using a differential thermoa analysis / thermogravimetric device carried out.

The conditions for the experiments are given in Table 5 below.

Table 5

Sample amount

Sensitivity (full scale)

invention
Comparative experiment 2

78.8
60.2

DTA

(μ ν)

250
250

Temp.

(mV)

50
50

Krhilztings · On- AimosphUre

rate / calculation

("C / min) (mm / h)

IO
IO

300
300

(N; ml / niiii)

30th
30th

12.2. Results

The following can be read from the DTA curves.

The DTA curve according to the invention shows a peuk that originates from an endothermic process at around 390 ° C. In contrast, the DTA curve of comparative experiment 2 shows three endothermic peaks at around 190.30 ObAW ^ O ⁰ C. The DTAs differ on these catfish -Curves, although they are quite similar to each other,

Further ItIDt from the TC-Kurvcn seen that dus crflndungsgemüße product is subject of about 33O ⁰ C in a weight loss, while dus product of 2 Vcrglcichsvcrsuchs a weight loss of 300 to 32O ⁰ C in the subject.

Taking into account that the glass beads that come with

are coated the polymer, no thermal VcrUnderung temperature up SOO ⁰ C are in a temperature range of Ruum so may mar assume that the above-mentioned sub differences in thermal properties between derr eriindungsgemüßen product and the product de! Comparative experiment 2 resulted essentially from a ου thermal degradation of the polymer roll.

Compare example 4 4.!. Purpose of the example

The example was performed to demonstrate the coating process according to the invention with the process ren of GB-PS 10 23 694 to compare.

4.2. VeISUChC (TCiI 1)

Manufacture of polymer / sand composites

(1) Ek became a polymer / sand combination manufactured according to the process according to the invention.

A mixture of 1000.0 g of sand passed through a sieve with 150 mesh went, 150.0 g methyl methacrylate, 50.0 g of Hydroxyethyl methacrylate, 15.0 g of NaI ISOi and 4000 g of water were reacted at 50 "C for 3 hours. The resulting product was then filtered through collected and dried, leaving 1182 g of a polymer / sand composition were obtained. The polymer content of the composition was 15.4%.

(2) Another polymer / sand composition was made according to the method of GB-PS 10 25 694 manufactured.

7.5 g of methyl methacrylate, 2.5 g of hydroxyethyl methacrylate and 50.0 g of sand were added to 350 g of heptane. The mixture was kept with stirring at 65 ° C. for 5 hours, filtered off and then dried. However, only 49.9 g of solid (sand) were obtained by this method.

4.2. Trials (part 2)

Manufacture of injection molded articles and
Measurement of their mechanical strength

The polymer / sand composition obtained by the above method (1) was put in a metal mold and subjected to injection molding under the following conditions:

Temperature of the metal mold

Injection molding pressure

Injection molding time

Shape of the metal molds

150 ⁰ C

200 kg / cm ²

3 minutes

20x 130x 10 mm

(rectangular)

It was found to show the flexural strength of the molded article obtained in this way Measured using an Instron universal / ugtestgenit (model TT-CM from Instron Co., USA). the Results of the measurements are shown in Table 9 below.

Table 6

Shaped
object

Flexural strength
(kg / cm- ')

372

4.3. Results

J'polymer content

15.4

The flexural strength of the article according to the invention is remarkably resentful. In addition, it was definitely established that after the procedure of GB-PS 10 25 694 - depending on the type of monomers - not even a polymerization reaction tion takes place. In lines 9 to K) on page 2 of this patent specification it is stated that the polymerizable Liquid can be present in monomeric or partially polymeric sicrtcr viscous form. Fs is open lent that the process of this patent cannot be carried out with low-viscosity monomers which are used in accordance with the invention.

Claims (1)

Claim: Process for coating finely divided inorganic material with a polymer which one the polymer by solution, emulsion or suspension polymerization of a vinyl monomer in amounts of 1 to 100 parts by weight of the monomer per 100 parts by weight of the inorganic Material prepared in the presence of a catalyst and coated with the polymer discrete Particles obtained, characterized that one the vinyl monomer in the presence of glass particles, abrasive particles or sand particles polymerized as a finely divided inorganic material and bisulfite ion as a catalyst.