Composite material and method of producing same

The composite material, which is a solid porous carrier, whose pores are filled with a polymer, a polyolefin having the molecular weight not less than 300,000, the degree of pore filling with said polymer being at least 4 percent of the total volume of the pores, in which the ratio of the carrier mass to the mass of the polymer is 50-99.5:50-0.5. The method of producing said composite material consists in precipitation, from the gas phase, of a complex organometallic catalyst consisting of a compound of a transition metal and of an organic compound of a metal in the 2nd or 3rd group of the Periodic Table, inside the pores of a solid porous carrier, and in polymerization of olefins from the gas phase on said catalyst, precipitated in the pores of the solid porous carrier, at a temperature of 50.degree.-165.degree. C. and a pressure of 1-60 atm. The composite material is characterized by high mechanical strength (compression strength reaching 100-200 kg/sq. cm) high frost resistance, and hydrophobic properties. The proposed method effectively controls the degree of filling the carrier pores with the polymer (from at least 4 percent of the total volume of the pores), and can be used to manufacture composite materials possessing a predetermined set of properties.

FIELD OF THE INVENTION 
This invention relates to composite materials and methods of producing 
them. Said composite materials are used in the industry of building 
materials as light-weight aggregates of concretes. 
BACKGROUND OF THE INVENTION 
Known in the prior art is a composite material which is a solid porous 
carrier, concrete, whose cells are filled with low-molecular weight (under 
70,000) polyethylene, the concrete cells being filled with the 
polyethylene to 0.5-1.0 percent with respect to the total volume of the 
cells. 
Known in the prior art is another method of producing said composite 
material by impregnating a solid porous carrier, concrete, with a solution 
or a melt of a polymer, a low-molecular weight polyethylene. 
The viscosity of solutions and melts is high and it is therefore difficult 
to fill the pores of the carrier to the required extent. It has been 
stated above that only about 0.5-1.0 percent of the total volume of the 
carrier cells are filled. It should be understood that the smaller the 
diameter of the pores, the lesser the filled volume of the pores. This 
disadvantage is responsible for the manufacture of composite materials 
possessing inadequate properties, namely, low resistance to frost and 
moisture. 
Known in the prior art is a composite material which is a solid porous 
carrier, for example, ceramsite, whose cells are filled with polystyrene 
or polyacrylates. The ratio of the carrier mass to the mass of the polymer 
is 97:3. 
Known in the prior art is another method of producing said composite 
material by impregnating a solid porous carrier, e.g. foamed clay, with a 
liquid monomer or a solution of the monomer, for example styrene, acrylic 
acid, or its derivatives, and also with an initiator of a radical chain 
polymerization, with subsequent thermal or radiation polymerization of the 
monomers in the carrier pores. 
This method does not provide a reliable control of the filling of pores 
with polymers either, and it is therefore difficult to obtain a composite 
material possessing the prescribed properties. 
SUMMARY OF THE INVENTION 
It is an object of this invention to provide a composite material having 
high strength, frost resistance, and hydrophobic properties. 
Another object of the invention is to provide a method of producing a 
composite material having said properties. 
In accordance with these and other objects the invention consists in that 
proposed herein is a composite material, which is a solid porous carrier, 
whose pores are filled with a polymer, in which according to the 
invention, the composite material contains a polyolefin as the polymer, 
the molecular weight of said polyolefin being not less than 300,000, the 
pores of the carrier being filled with the polymer to at least 4 percent 
of the total volume of the pores, the ratio of the carrier mass to the 
mass of the polymer being 50-99.5:50-0.5. 
The proposed composite material has a high strength (the material has a 
compression strength of 100-200 kg/sq.cm). Said material is also 
characterized by a high resistance to frost (the material withstands 540 
cycles without fracture, which corresponds to 180 days; the frost-defrost 
cycle consists of cooling the material minus 2.degree. to minus 3.degree. 
C. for 4 hours with subsequent heating to 20.degree. C. for 4 hours). 
Moreover, the proposed material is highly hydrophobic (the hydrophobic 
properties are determined by absorption of water at a temperature of 
20.degree. C.; for example, a composite material which is Ceramsite having 
the bulk weight of 600 kg/cu.m., whose pores are filled with polyethylene 
to 15 percent of their total volume, the ratio of the carrier mass to the 
mass of the polymer being 93:7, absorbs 0.1 percent by weight of water). 
The object of this invention is also to provide a method for producing said 
composite material, which according to the invention consists in 
precipitation, from the gas phase, of a complex organometallic catalyst 
consisting of a compound of a transition metal and of an organic compound 
of a metal in the 2nd or 3rd group of the Periodic Table, in the pores of 
a solid porous carrier, and in polymerization of olefins, from the gas 
phase, on said catalyst precipitated in the pores of the solid porous 
carrier, at a temperature of 50.degree.-165.degree. C., and a pressure of 
1-60 atm; said precipitation is effected in two steps, the first component 
of the catalyst, viz., the compound of a transition metal, being 
precipitated at the first stage, and the second component of the catalyst, 
viz., the organic compound of a metal standing in the 2nd or 3rd group of 
the Periodic Table, at the second stage; precipitation from the gas phase 
of the first component of the catalyst is effected at a temperature of 
20.degree.-300.degree. C. and at varying pressure which is first raised by 
at least 30 percent of the initial pressure and then lowered to at least 
the starting pressure, the latter being maintained within the range from 
0.05 to 1.2 atm; the second component of the catalyst is precipitated from 
the gas phase at a temperature of 20.degree.-165.degree. C. 
The catalyst components can be precipitated in the pores of a solid porous 
carrier in the sequence as described above, before carrying out the 
polymerization process. 
Another version is also possible by which the first component of the 
catalyst, the compound of a transition metal, is precipitated in the pores 
of a solid porous carrier before carrying out the polymerization process, 
whereas the second component of the catalyst, the organic compound of a 
metal in the 2nd or 3rd group of the Periodic Table, is precipitated 
simultaneously with the polymerization process. 
In order to improve the frost resistance, mechanical strength, and 
hydrophobic properties of the composite material, it is recommended that, 
after carrying out the polymerization process, the obtained composite 
material be treated at a temperature of from 120.degree. to 200.degree. C. 
for 10-30 minutes. 
The proposed method provides a composite material of a high quality 
possessing a set of predetermined properties. The method can be used to 
control, within wide limits, the degree of filling the carrier pores with 
a polymer (from at least 4 percent of the total volume of the pores), and 
hence the properties of the obtained composite material can be varied 
within wide limits as well. 
DETAILED DESCRIPTION OF THE INVENTION 
Polyolefins, for example, polyethylene, polypropylene, polyisobutylene, 
polymethylpentene, copolymers of various olefins, e.g., a copolymer of 
ethylene with propylene can be used as polymers in the proposed composite 
material. 
A solid porous carrier for said composite material can be selected from the 
group containing, for example, Ceramsite, fired clay, expanded perlite, 
foamed glass, tripoli gravel, porous slags. The size of pores of the 
carrier can vary within wide limits (from a micron to a few millimeters). 
The starting olefins that can be used in the proposed method of producing 
composite material, can be for example, ethylene, propylene, butene, 
methylpentene. Individual olefins and their various combinations can be 
used for the purpose. 
The proposed method of producing the composite material can be realized as 
follows. 
Whenever necessary, a solid porous carrier is dried before loading into a 
reaction vessel at a temperature of from 100.degree. to 300.degree. C. for 
1-3 hours. The carrier is then loaded into the reactor which is blown with 
an inert gas or evacuated. Vapours of a compound of a transition metal 
(the first component of a complex organometallic catalyst) are then 
delivered into the reactor, either individually or with a stream of an 
inert carrier gas. The temperature in the system is maintained, depending 
on the nature of the transition metal compound, within the range of from 
20.degree. to 300.degree. C., whereas the initial pressure of the gas in 
the system is maintained within the range of from 0.05 to 1.2 atm. The gas 
pressure in the system is then raised by at least 30 percent of the 
initial value. The gas pressure in the system is then lowered to at least 
the initial value. In the meantime, the carrier gas and the vapours of the 
transition metal compound, or the vapours of the transition of metal 
compound alone, fills the pores of the solid porous carrier and the first 
component of the catalyst is precipitated in them. 
Depending on the type of a solid porous carrier and the desired degree of 
pore filling with the polymer, the quantity of the compound of a 
transition metal precipitated in the pores ranges from 0.001 to 0.05 
percent of the mass of the porous carrier. 
One cycle of raising and lowering the pressure can be sufficient, but 
whenever the diameter of pores in the solid carrier is small, the 
procedure can be repeated once, twice, etc. 
As soon as the first component of the complex organometallic catalyst has 
been deposited in the pores of the carrier, the second component of the 
catalyst, namely an organic compound of a metal of the 2nd or 3rd group of 
the Periodic Table, is introduced into the reaction vessel. The 
temperature inside the reactor should be maintained at the level of from 
20 to 165.degree. C. Said organometallic compound is introduced into the 
reactor either in the vapour form with the flow of the inert carrier gas, 
or in the vapour form with a flow of the gaseous monomer. The second 
component of the catalyst is introduced into the reactor in a quantity at 
least equal to the quantity of the precipitated first component. The 
optimum quantity of the second component of the catalyst is 0.003 to 0.15 
percent of the carrier mass. 
If the second component of the catalyst is delivered into the reactor in 
the form of vapours alone, or in the form of vapours with a flow of an 
inert gas (carrier gas), the second component of the catalyst is 
precipitated before carrying out the polymerization process. As soon as 
the second component has been precipitated in the pores of the carrier, 
and the complex organometallic catalyst is accordingly formed, olefins are 
polymerized. To that end, olefins are delivered into the reactor and the 
polymerization is effected, from the gas phase, at a temperature of 
50.degree.-165.degree. C. and a pressure of from 1 to 60 atm. 
If the second component of the catalyst is introduced into the reactor in 
the vapour form with a flow of the monomer, said component of the catalyst 
is precipitated in the pores of the carrier simultaneously with the 
polymerization process. 
It is recommendable that the processes of precipitation of the first and 
second components of the catalyst, and of the polymerization of olefins be 
carried out with stirring the solid porous carrier. Stirring can be 
effected under the conditions of fluidized or filtering bed, mechanical 
stirring or stirring by gravity, by pneumatic or vibrational transport. 
When the required degree of pore filling with the polymer has been attained 
(from at least 4 percent of the total volume of the pores), the 
polymerization process is stopped by lowering the monomer pressure (by 
discontinuing its delivery into the reactor) or by lowering the 
temperature. The finished product (composite material) is then cooled if 
necessary, and discharged from the reactor. 
The degree of pore filling with the polymer can be varied within wide 
limits by changing the process temperature, pressure, and varying the time 
of the polymerization process. 
In order to improve the material strength, resistance to frost, and 
hydrophobic properties, the composite material can be given an additional 
thermal treatment at a temperature of from 120.degree. to 200.degree. C. 
for 10-30 minutes. During this treatment, the polymer is fused in the 
carrier pores and closes them.

For a better understanding of the invention the following examples of its 
practical embodiment will be given below by way of illustration. 
EXAMPLE 1 EXAMPLE 1 
92 kg of ceramsite gravel (granule size 15-20 mm, bulk weight 500 kg/Cu.m., 
compression strength 28 kg/sq.cm., total porosity 50 percent by volume) 
are dried at a temperature of 200.degree. C. and then placed into a 
reactor. The reactor is evacuated, and then at a temperature of 20.degree. 
C. 4.1 g of vanadium tetrachloride in the vapour form is introduced 
thereinto with a flow of nitrogen. The initial pressure of the gas in the 
reactor is 0.1 atm. The gas pressure is then raised to 0.5 atm. and then, 
in 1-2 minutes, the pressure is lowered to the initial value. Vanadium 
tetrachloride is deposited in the carrier pores as a result of this 
procedure. Then at the temperature of 20.degree. C. diethylaluminium 
chloride (12 g), in the vapour form, is introduced into the reactor with a 
flow of ethylene. The reactor is thermostatted at 50.degree. C., and the 
ethylene pressure is raised to 60 atm. Under the specified temperature and 
pressure conditions ethylene polymerization is carried out. The total 
duration of the polymerization process is 120 minutes. On completion of 
the polymerization the reactor is purged with nitrogen and the resultant 
product is discharged. 
The thus-prepared composite material contains 8.4 kg of polyethylene. The 
degree of pore filling is 18 percent of the total pore volume. The ratio 
of the mass of the porous carrier to the mass of the polymer in the 
obtained composite material is 91:9. The molecular weight of the polymer 
is 700,000. 
The compression strength of the obtained composite material is 130 
kg/sq.cm. 
To determine the frost resistance of the composite material, it is first 
cooled to minus 2.degree.-minus 3.degree. C. for 4 hours, and then heated 
to 20.degree. for 4 hours. The material remains still undestroyed after 
540 cycles of cooling and heating. 
The non-filled Ceramsite gravel is destroyed after 15 cycles. 
The composite material prepared as described in this Example absorbs 0.3 
mass percent of water. 
The starting carrier (without polyethylene) absorbs 24 mass percent of 
water. 
In order to increase the strength, frost resistance, and hydrophobic 
properties, the composite material is loaded into a reactor and heated at 
a temperature of 190.degree. C. for 10 minutes. The material is then 
cooled and unloaded from the reactor. After this thermal treatment the 
material has the following specifications: compression strength, 152 
kg/sq.cm; frost resistance, 540 cycles; absorption of moisture, 0.05 
percent by weight. 
EXAMPLE 2 
A reactor is loaded with 190 kg of tripoli gravel (granule size 10-15 mm, 
bulk weight 600 kg/cu.m., compression strength 56 kg/sq.cm, total porosity 
30 percent by volume, absorption of moisture 17 percent by weight, and 
frost resistance 20 cycles), and the material is dried at a temperature of 
200.degree. C. The reactor is cooled to 165.degree. C., evacuated, and 30 
g vanadium tetrachloride is introduced into the reactor together with a 
current of nitrogen. The initial pressure of the gas in the reactor is 0.5 
atm. The pressure inside the reactor is raised to 0.7 atm and then lowered 
to 0.3 atm. Vanadium tetrachloride is thus precipitated in the carrier 
pores. At 165.degree. C. 40 g triethylaluminium vapours is introduced into 
it with a current of nitrogen. Propylene is then delivered into the 
reactor to build up a pressure of 20 atm. Propylene is polymerized at a 
temperature of 165.degree. C. The overall time of the polymerization 
process is 90 minutes. The reactor is then cooled, blown with nitrogen to 
remove non-polymerized propylene, and the obtained composite material 
unloaded from the reactor. 
The composite material thus obtained contains 0.95 kg of polypropylene. The 
degree of pore filling is 4 percent with respect to the total pore volume. 
The ratio of the mass of the porous carrier to the mass of the polymer is 
99.3:0.7. The molecular weight of the polymer is 300,000. 
The compressive strength of the composite material is 80 kg/sq.cm. Frost 
resistance of the material is 340 cycles. Absorption of water is 0.12 
percent by weight. 
EXAMPLE 3 
A reactor is loaded with 1.3 g of expanded perlite in the form of granules 
sizing 3-10 mm (the bulk weight 270 kg/cu.m., compression strength 14.2 
kg/sq.cm, total porosity 83 percent by volume, absorption of moisture 40 
percent by weight) and the material is dried at a temperature of 
200.degree. C. The reactor is then evacuated. The temperature in the 
reactor is simultaneously lowered to 90.degree. C. When the temperature in 
the reactor has been stabilized, 1.3 g titanium tetrachloride, in the 
vapour form, is added along with a current of nitrogen. The initial 
pressure of the gas inside the reactor is 0.07 atm. The perlite charge is 
stirred inside the reactor by gravity. The gas pressure inside the reactor 
is raised to 1 atm and then lowered again to 0.7 atm. 5 g diethylzinc 
vapour is introduced into the reactor with a current of nitrogen. The 
reactor is then blown with a mixture of ethylene and alpha-butene, taken 
at the molar ratio of 4:1. The copolymerization process is carried out at 
a temperature of 90.degree. C. and a pressure of 1 atm. The time of the 
polymerization process is 15 hours. The reactor is then blown with 
nitrogen and simultaneously cooled to 20.degree. C. The obtained composite 
material is then unloaded from the reactor. 
The composite material contains 0.23 kg of copolymer of ethylene with 
alpha-butene. The degree of pore filling is 9 percent with respect to the 
total volume of the pores. The ratio of the porous carrier (expanded 
perlite) mass to the mass of the copolymer is 85:15. The molecular weight 
of the copolymer is 300,000. 
The compressive strength of the composite material is 25 kg/sq.cm. Frost 
resistance of the material is 400 cycles. Absorption of moisture is 1.0 
percent by weight. 
EXAMPLE 4 
A reactor is loaded with 72 kg of dried Ceramsite gravel (granule size 
15-20 mm, bulk weight 500 kg/cu.m., compressive strength 28 kg/sq.cm, 
total porosity 50 percent by volume, frost resistance 15 cycles) and blown 
through with nitrogen for 15 minutes. The reactor is then heated to 
70.degree. C. and 5.3 g vanadium oxytrichloride, in the vapour form, is 
introduced into it along with a current of nitrogen. The initial gas 
pressure in the reactor is 1.2 atm. The pressure of gas in the system is 
raised to 2.0 atm and then lowered again to 1.2 atm. Vanadium 
oxytrichloride is thus precipitated inside the carrier pores. 5 g 
triisobutylaluminium is introduced into the reactor, in the vapour form, 
along with a current of ethylene. The process of precipitation of 
triisobutylaluminium in the carrier pores occurs simultaneously with 
ethylene polymerization. The pressure of ethylene in the system is 5 atm. 
The polymerization process is carried out at a temperature of 70.degree. 
C. and the above-specified pressure. The overall time of the 
polymerization process is 4.5 hours. On completion of the polymerization 
process, the reactor is blown with nitrogen, cooled to 20.degree. C., and 
the resulting composite material is unloaded. 
The composite material contains 4.5 kg of the polymer. The degree of pore 
filling is 12 percent of the total volume of the pores. The ratio of the 
mass of the porous carrier to the mass of the polymer in the composite 
material is 94:6. The molecular weight of the polymer is 700,000-750,000. 
The compressive strength of the thus-prepared composite material is 70 
kg/sq.cm. Frost resistance of the material is 500 cycles. Absorption of 
moisture is 0.1 percent by weight. 
EXAMPLE 5 
A reactor is loaded with 1.2 kg of foamed glass, dried at 200.degree. C., 
in the form of granules sizing 5-10 mm (bulk weight 40 kg/cu.m., 
compressive strength 0.5 kg/sq.cm, total porosity 90 percent by volume). 
The reactor is evacuated and the temperature is then raised to 300.degree. 
C., the carrier is stirred continually, and 2 g iron trichloride is added, 
in the vapour form, together with a flow of nitrogen. The initial gas 
pressure unside the system is 0.5 atm. The pressure is then raised to 1 
atm and then lowered to 0.6 atm. Iron trichloride is thus precipitated in 
the pores of foamed glass. The reactor is then cooled to 70.degree. C. and 
2.4 g triisobutylaluminium is introduced thereinto in the vapour form. 
Ethylene is then introduced into the reactor to build up a pressure of 25 
atm. Ethylene is polymerized at a temperature of 70.degree. C. and under 
the above-specified pressure. The overall time of the polymerization 
process is 3.5 hours. On completion of the polymerization process the 
reactor is blown with nitrogen, cooled to 20.degree. C., and the composite 
material unloaded from the reactor. 
The obtained composite material contains 1200 g of polyethylene. The degree 
of pore filling is 30 percent of their total volume. The ratio of the 
porous carrier mass to the mass of the polymer is 50:50. The molecular 
weight of the polymer is 500,000. 
The compression strength of the material is 5 kg/sq.cm. Absorption of water 
is 1.0 percent by weight. 
To improve the strength, frost resistance, and hydrophobic properties of 
the obtained composite material, it is loaded into the reactor and kept 
there for 30 minutes at a temperature of 120.degree. C. The material is 
then cooled to 20.degree. C. and unloaded from the reactor. The new 
characteristics of the thus-treated composite material are as follows: 
compressive strength 10 kg/sq.cm, absorption of moisture 0.5 percent by 
weight.