Cushion or trackbed material for use in riding-ground

A cushion or trackbed material for use in a riding-ground is obtained by coating sand with a carboxyl-containing olefin polymer and an oxygen-containing wax.

The present invention relates to a cushion or trackbed material for use in 
a (horse) riding-ground and more particularly to a cushion or trackbed 
material suitable for sports facilities for race horse such as race dirt 
course. 
Heretofore, in various riding-grounds such as race dirt courses, a trackbed 
(or loadbed) material and a cushion material are laid thereon uniformly 
using natural sand, etc. 
In a riding-ground such as horse race track using natural sand, if the sand 
is used as a trackbed material there is obtained an appropriate supporting 
force, while if it is a cushion sand, there are obtained appropriate 
cushioning property and foothold. Therefore, a riding-ground using natural 
sand is preferred as a riding-ground suitable for horse exercise and it is 
well drained if only daily maintenance and management are performed to a 
satisfactory extent. 
Usually, when a race dirt course is in a somewhat wet state, this state is 
regarded as being suitable for the exercise and running of horse. It is 
said that this state is attained at an optimum water content or 
thereabouts of natural sand used as a cushion material. 
However, in a dry season such as the summer season wherein the atmospheric 
temperature rises, the water content of the cushion material becomes 
lower, resulting in that the foothold is poor, thus impairing smooth 
running of horse; besides, dust is blown up and impedes the sight of man 
and horse, thus causing an accident. In order to avoid these 
inconveniences it is required to sprinkle water. 
Conversely, on a rainy day in the rainy season, the water content of the 
cushion material and that of trackbed material as a support layer become 
higher than necessary, with the result that in the cushion layer, muddy 
lumps are spattered with running of horse, thus impeding the sight of 
succeeding man and horse and causing an accident. 
In a cold season, since gravitational water and adsorbed water between sand 
grains are frozen, not only the exercise of horse is impeded but also 
there is a danger of a violet fall, etc. and hence it is required to stop 
the horse exercise or race. 
On the other hand, as a method for preventing dusting, freezing and mudding 
of a soil ground, there has been proposed a method wherein an asphalt 
emulsion or an oil such as a heavy oil is scattered or mixed into the 
soil. However, since this method is for a compacted soil, if it is applied 
to a cushion material and a trackbed material, using natural sand, there 
will arise such problems as deteriorated draining property, flowing-out of 
oil, emission of offensive smell, and concretion of sand in the cushion 
material. Thus, it is difficult to prevent dusting, freezing and mudding 
while maintaining the excellent characteristics of natural sand such as 
excellent cushioning and draining properties. Further, outflow or 
volatilization of oil due to rainfall not only reduces the dusting and 
freezing preventing effect but also causes oil to adhere to man and horse, 
buildings, etc. Thus, such conventional method is inferior in 
utilizability. 
The object of the present invention resides in overcoming the 
above-mentioned drawbacks of the conventional riding-ground cushion and 
trackbed materials, particularly resides in providing all-weather type 
riding-ground cushion and trackbed materials which are not dependent on 
weather conditions with respect to their utilizability. 
SUMMARY OF THE INVENTION 
The present invention resides in a cushion or trackbed material for use in 
a riding-ground comprising sand coated with a coating material, the 
coating material comprising an olefin polymer having a carboxyl group or 
an anhydride group thereof and/or an oxygen-containing wax. 
DETAILED DESCRIPTION OF THE INVENTION 
The olefin polymer having a carboxyl group or an anhydride group thereof 
used in the present invention is not substantially limited if only it is a 
homopolymer or copolymer of olefin(s) having a carboxylic acid group or a 
carboxylic acid anhydride group. Preferred olefins are mono- or diolefins 
having 2 to 8 carbon atoms. For example, there may be used copolymers of 
one or more of olefins such as monoolefins, e.g. ethylene, propylene, 
butene, isobutene, hexene and cyclohexene, and diolefins, e.g. butadiene 
and isoprene, with unsaturated carboxylic acids or derivatives thereof. 
Examples of such copolymers also include graft polymers obtained by 
graft-polymerizing unsaturated carboxylic acids or derivatives thereof 
with olefin polymers. As examples of such graft polymers there are 
mentioned modified polyolefins obtained by graft-modifying polyolefins 
resulting from homo- or copolymerization of olefins such as monoolefins, 
e.g. ethylene, propylene, butene, isobutene, hexene and cyclohexene, or 
diolefins, e.g. butadiene and isoprene, with unsaturated carboxylic acids 
or derivatives thereof. 
As preferred examples of such unsaturated carboxylic acids there are 
mentioned .alpha.,.beta.-unsaturated mono- and dicarboxylic acids having 2 
to 8 carbon atoms such as acrylic, maleic, fumaric, tetrahydrophthalic, 
itaconic, citraconic, crotonic and isocrotonic acids. Examples of their 
derivatives include acid halides, amides, imides, anhydrides, and esters. 
More concrete examples are malenyl chloride, maleimide, maleic anhydride, 
citraconic anhydride, monomethyl maleate, dimethyl maleate, and glycidyl 
maleate. 
Preferred olefin polymers having a carboxyl group or an anhydride group 
thereof are modified polyolefins obtained by graft-modifying the foregoing 
polyolefins with unsaturated carboxylic acids or derivatives thereof. 
Above all, modified polyolefins obtained using alkenyl succinic anhydride 
are preferred. 
The above modified polyolefins can be prepared by any of known methods, 
e.g. a method wherein unsaturated carboxylic acids or derivatives thereof 
are added to polyolefins and graft-copolymerized therewith. For efficient 
graft copolymerization of unsaturated carboxylic acids, it is desirable 
that the reaction be carried out in the presence of a radical initiator. 
Examples of radical initiators include organic peroxides and organic 
peresters such as benzoyl peroxide, dicumyl peroxide, di-tert-butyl 
peroxide, tert-butyl perbenzoate, cumyl perpivalate, and azo compounds, 
e.g. azobisisobutyronitrile. 
In graft-modified polyolefins it is desirable that 0.05 to 5.0 moles, 
preferably 0.1 to 4.0 moles, on the average of unsaturated carboxylic 
acids or derivatives thereof be added to 1 mole of polyolefins. 
As polyolefins employable in preparing the olefin polymer having a carboxyl 
group or an anhydride group thereof according to the present invention, 
polybutene and polyisobutylene are particularly preferred because they are 
easily available and also in view of the use and performance of the 
resulting product. The molecular weight of the starting polyolefin may be 
suitably selected according to the kind of olefin(s) used and for what 
purpose the resulting product is to be used. For example, in the case of 
polybutene, the molecular weight thereof is preferably in the range of 300 
to 3000. 
The details of how to prepare a graft-modified polyolefin are disclosed in 
Japanese Patent Laid Open No. 89316/1975, which is incorporated herein for 
reference. 
As examples of the oxygen-containing wax used in the invention there are 
mentioned natural waxes such as carnauba wax, montan wax, rice bran wax, 
bees wax and Japan tallow, synthetic waxes such as microcrystalline wax 
oxide and paraffin oxides, secondary modified products obtained by various 
reactions of those waxes, polyvalent carboxylic acid-modified waxes 
obtained by an addition reaction of hydrocarbon waxes and unsaturated 
polyvalent carboxylic acids or anhydrides thereof, and mixtures thereof. 
Preferred as the oxygen-containing wax used in the present invention is an 
oxygen-containing wax obtained by reacting 100 parts by weight of a 
hydrocarbon wax having a melting point in the range of 50.degree. to 
90.degree. C. and 3-25 parts by weight of an unsaturated polyvalent 
carboxylic acid or an anhydride thereof. The details of how to prepare it 
is disclosed in Japanese Patent Laid Open No. 96094/1974, which is 
incorporated herein for reference. Further preferred as the 
oxygen-containing wax used in the present invention is an 
oxygen-containing wax obtained by mixing 10-80, preferably 30-70, parts by 
weight of a petroleum distillate wax having a melting point in the range 
of 50.degree. to 85.degree. C. with 90-20, preferably 70-30, parts by 
weight of a polyolefinic wax (II) having a melting point of 36.degree. to 
120.degree. C., a number average molecular weight of 310 to 1,000 and 5 to 
50 double bonds per 1,000 carbon atoms, and then reacting 100 parts by 
weight of the resulting mixture with 3-25, preferably 8-18, parts by 
weight of an unsaturated polyvalent carboxylic acid or an anhydride 
thereof. More concrete contents thereof are disclosed in Japanese Patent 
Laid Open No. 81306/1979, which is incorporated herein for reference. 
As to the coating, material which constitutes the race tack cushion 
material and race trackbed material of the present invention, its optimum 
weight, etc. are determined according to purposes of use. The proportion 
of the coating material is usually in the range of 0.1 to 10 wt % based on 
a dry weight of sand. As to the composition of the coating material, the 
proportion of the olefin polymer having a carboxyl group or an anhydride 
group thereof is 100-0 wt % and that of the oxygen-containing wax is 0-100 
wt %, preferably the polymer 95-50 wt % and the oxygen-containing wax 5-50 
wt %. 
Examples of the sand used in the present invention include natural sands 
such as river sand, mountain sand and sea sand, artificial sands such as 
crushed sand, as well as silica sand and granulated slag from blast 
furnace. No special limitation is placed thereon if only the required 
conditions are satisfied. In order to ensure the coating of sand grains 
with the coating material, it is desirable to use a dehydrated dry sand. 
In the case of using sand as the cushion material of the invention, it is 
desirable that the sand pass 100% through a 2.36 mm sieve and be of a 
single grain size, while in the case of using sand as the trackbed 
material, it is desirable that the sand pass 100% through a 2.36 mm sieve 
and be of a continuous grain size. 
The cushion material and the trackbed material can each be produced easily 
by mixing sand and the coating material. As the mixing method, there may 
be adopted, for example, plant mixing or site mixing. But, plant mixing is 
preferred in order to obtain homogeneous race track cushion material and 
trackbed material. Particularly, it is desirable that the mixing 
temperature be in the range of 100.degree. to 180.degree. C. 
In the cushion material according to the present invention, the coating 
material having a specific composition exhibits a moderate viscosity and 
excellent coating forming property and water resistance, so it is possible 
to form a strong coating on each sand grain, whereby the coating material 
can be prevented from flowing out in a rainfall condition and the coated 
sand grains can be mutually bound temporarily to a moderate extent, and 
hence it is possible to suppress the formation of dust without sacrificing 
the excellent foothold and cushioning property of natural sand at an 
optimum water content thereof or thereabouts. 
The trackbed material according to the present invention, which retains the 
same properties as those of the cushion material, can ensure a required 
supporting force. 
Moreover, the cushion material and trackbed material of the present 
invention exhibits high water permeability, high draining property equal 
to or even higher than that of natural sand, and further exhibits a 
hydrophobic nature, so that gravitational water or adsorbed water is 
little retained between sand grains. Therefore, it is possible to suppress 
mudding and a freezing phenomenon of water, and coupled with the 
non-freezing property of the coating material, it is possible to prevent 
freezing of the cushion material. Further, since the trackbed material of 
the present invention has high draining property and hydrophobic nature, 
it can ensure a sufficient supporting force even in a rainfall condition. 
Besides, these effects can be ensured over a long period because the 
coating material superior in weathering resistance adheres strongly to the 
coating material, and such effects can be always exhibited constantly 
without deterioration even when the atmospheric temperature changes, 
because the coating material does not become brittle at low temperatures. 
Additionally, unlike such oils as heavy oils, the coating material is low 
in the intensity of smell and does not emit an offensive smell. Thus, a 
race dirt course or the like using the cushion material of the present 
invention can always maintain a good race track condition independently of 
weather conditions.

EXAMPLES 
Examples of the present invention and comparative examples will be 
described below, but it is to be understood that the invention is not 
limited thereby. 
EXAMPLE 1 
Table-1 below shows properties of cushion sand, trackbed sand, alkenyl 
succinic anhydride (maleinated polybutene HVM-100, a product of Nippon 
Petrochemicals Co., Ltd.) and oxygen-containing wax (POWAX H-10, a product 
of Nippon Oil Co., Ltd.) which were used for preparing specimens. Test 
items and test results are as set forth in the same table. 
TABLE 1 
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Measured Sand 
Item Value Cushion Trackbed 
HVM-100 H-10 
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2.36 mm 100 100 
Percent 
0.6 61.8 65.5 
Passing 
0.3 20.6 30.0 -- -- 
Weight 0.15 3.6 6.6 
(%) 0.075 0.1 0.6 
Specific 
Dry surface 
2.641 2.578 
Gravity 
Bulk 2.621 2.609 -- -- 
Apparent 2.674 2.662 
Water Absorption (%) 
0.75 1.22 
Acid Value (mgKOH/g) 
-- -- 47 55 
Kinematic Viscosity 
-- -- 654 -- 
(cSt @ 100.degree. C.) 
Melting Point (.degree.C.) 
-- -- -- 69 
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(1) Waterproofness Test 
(About 300 ml of distilled water or tap water is poured into a beaker, then 
the temperature is adjusted to 50.degree. C., and 20 g of each sample is 
placed therein, followed by heating for 60 seconds, thereafter whether the 
coating material is floating on the water surface is checked.) 
Compositions and test results are as shown in Table-2 below. 
TABLE 2 
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Composition 
1 2 3 
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Natural Sand 
100 100 100 
HVM-100 1.2 0.9 
H-10 1.2 0.3 
Observation 
Floating of Floating of Floating of 
the coating the coating the coating 
material is material is material is 
not observed. 
not observed. 
not observed. 
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(2) Water Permeation Test 
(Cushion sand and trackbed sand are mixed with coating materials followed 
by compacting and specimens thus obtained are subjected to a water 
permeation test according to water permeation test defined by JIS A 1200.) 
The results obtained are as shown in Table-3. 
TABLE 3 
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Permeation 
Coefficient 
Material Composition cm/sec 
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Natural sand 
100 
Cushion 
present HVM-100 0.65 1.21 .times. 10.sup.-2 
Sand invention H-10 0.25 
conventional 
Natural sand 
100 1.11 .times. 10.sup.-2 
cushion sand 
Natural sand 
100 
Trackbed 
present HVM-100 0.9 
Sand invention H-10 0.3 1.05 .times. 10.sup.-2 
conventional 
Natural sand 
100 1.05 .times. 10.sup.-2 
cushion sand 
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(3) Freezing Test 1 
(Cushion sand and trackbed sand are mixed with coating materials followed 
by compacting and specimens thus obtained are immersed in water for 24 
hours, then are allowed to drain for 1 hour, and after standing 24 hours 
at -20.degree. C. there is conducted a proctor needle test.) The results 
obtained are as shown in Table-4 below. 
TABLE 4 
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Proctor 
Material Needle Value 
Touched Condition 
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Cushion 
present 15 kg The surface is 
Sand invention loosened easily by 
hand. 
conventional 
1100 kg completely frozen 
cushion sand like ice. 
Trackbed 
present 80 kg The surface is 
Sand invention loosened easily by 
hand. 
conventional 
1250 kg completely frozen 
cushion sand like ice. 
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As is apparent from Table-4, the mixtures with the coating materials 
incorporated therein are 1.4% and 6.4% in terms of proctor needle values 
and thus are little frozen, and their hardness is an easily loosened 
hardness with a finger tip. 
(4) Freezing Test 2 
(Cushion sand and trackbed sand are mixed with coating materials followed 
by compacting, then water is sprinkled over the upper surfaces of 
specimens thus obtained and thereafter draining was made for 1 hour. Then, 
after standing 24 hours at -20.degree. C., there is conducted a needle 
test). The results obtained are as shown in Table-5 below. 
TABLE 5 
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Proctor 
Material Needle Value 
Touched Condition 
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Cushion 
present 8 kg The surface is 
Sand invention loosened easily by 
hand. 
conventional 
1200 kg completely frozen 
cushion sand like ice. 
Trackbed 
present 10 kg The surface is 
Sand invention loosened easily by 
hand. 
conventional 
1200 kg completely frozen 
cushion sand like ice. 
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As is apparent from Table-5, the mixtures with the coating materials 
incorporated therein are 0.6% and 0.8% in terms of proctor needle values 
and thus are little frozen, and their surfaces are easily loosened with a 
finger tip. 
(5) Test of Change in Water Content 
(Cushion sand is mixed with coating materials followed by compacting, then 
specimens thus obtained are immersed in water, and water contents are 
determined at various draining times.) The results obtained are as shown 
in Table-6 below. 
TABLE 6 
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Composition 1 2 3 4 
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Natural Sand 
100 100 100 100 
HVM-100 -- 0.9 0.65 -- 
H-10 0.9 -- 0.25 -- 
Change in 
0 hr 14.4 25.7 17.6 34.7 
Water 0.5 hr 12.8 25.4 15.6 34.3 
Content 1.0 hr 11.9 25.0 14.7 33.7 
(%) 2.0 hr 10.8 23.9 12.1 33.7 
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As is apparent from Table-6, the mixtures with the coating materials 
incorporated therein are better drained than natural sand alone, and the 
mixtures containing H-10 (oxygen-containing wax) are still better 
drained.) 
(6) Surface Hardness Test 
Proctor needle test was conducted with respect to samples obtained by 
mixing sands with coating materials. The results obtained are as shown in 
Table-7 below. 
TABLE 7 
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Proctor 
Material Needle Value Touched Condition 
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Cushion 
present 3.5 kg Somewhat viscous 
Sand invention and is loosened 
easily with a 
finger tip. 
conventional 
4.5 kg Somewhat compact, 
cushion sand 
(optimum water 
but is loosened 
content) easily with a 
finger tip. 
Trackbed 
present 5.5 kg Somewhat viscous 
Sand invention and is loosened 
easily with a 
finger tip. 
conventional 
7.5 kg Somewhat compact, 
cushion sand 
(optimum water 
but is loosened 
content) easily with a 
finger tip. 
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The proctor needle value of the conventional sand is 4.5 kg at an optimum 
water content, while in a dry condition it is unmeasurable. The cushion 
material of the present invention corresponds to a natural sand which is 
in a somewhat wet state, and its proctor needle is by no means inferior to 
that of the natural sand. A similar tendency is observed also with respect 
to the trackbed material. 
(7) Determination of Smell 
Smell was determined with respect to a sample obtained by mixing sand with 
a coating material. The results obtained are as shown in Table-8 below. 
TABLE 8 
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Material Smell Remarks 
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Cushion present 246 Usually, assuming that 
Sand invention the smell value of air 
is 200, that of coffee 
conventional 
200 just after milling is 
cushion sand 400 or so. 
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Although the smell value of the sample obtained according to the present 
invention is a little larger than that of the conventional cushion sand, 
it is substantially odorless, free of any offensive smell induced by oil, 
etc. 
(8) Test of Supporting Force 
A trackbed material obtained by mixing natural sand with a coating material 
according to the present invention and a conventional trackbed material of 
natural sand were tested for supporting force after sprinkling of water. 
The results obtained are as shown in Table-9 below. 
TABLE 9 
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Material Proctor Needle Value (kg) 
______________________________________ 
Present invention 
39 
Conventional 31 
Trackbed Material 
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As is apparent from Table-9, the trackbed material containing the coating 
material is little deteriorated in supporting force. 
EXAMPLE 2 
An in-situ comparison was made between a race track cushion material and a 
trackbed material both according to the present invention and conventional 
cushion sand and trackbed sand. The materials and proportions thereof used 
are the same as in Example 1 (Table-3). The cushion material and the race 
trackbed material were obtained by wet-mixing 130.degree. C. heat-dried 
sand with HVM-100 and H-10 for 50 seconds, using an asphalt plant. 
The cushion material and trackbed material thus obtained and natural sand 
in a wet condition were laid uniformly at a predetermined thickness on a 
riding-ground using an asphalt finisher. Thereafter, comparative tests 
were conducted to check the following items with respect to their 
performance in one cold season. The results obtained are as set forth in 
Table-10. 
(1) Running Performance and Dust-proofness 
Gallop of horse was performed in a race track and the running performance, 
scattering of sand grains and dusting were observed visually. Between the 
natural sand in a wet condition and the cushion material and trackbed 
material according to the present invention there was no difference in 
running performance and dust-proofness, and the rack track was held in a 
good condition. However, when the natural sand was in a dry condition, the 
foothold was a little inferior and dusting was observed. 
(2) Draining Property and Outflow of Coating Material 
Water was sprinkled over the race track at a rate of 50 mm/hr and draining 
property was tested. As a result, all of the samples proved to have a 
satisfactory draining property without causing any inconvenience such as 
the stagnation of water on the surface. From the cushion material of the 
present invention there was observed no outflow of the coating material 
base on the sprinkling of water. 
After the sprinkling of water, the water contents of the race trackbeds 
were determined, which were found to be 16.5% and 7.3% in the cases of the 
natural sand and the trackbed material of the present invention, 
respectively. The trackbed material of the present invention was smaller 
in the amount of water retained therein than in the natural sand, and 
exhibited little deterioration in its supporting force. 
(3) Non-Freezing Property 
On the day after the confirmation of draining property using sprinkled 
water, the minimum atmospheric temperature was -5.8.degree. C., and a 
non-freezing property was observed by touching. The cushion material of 
the present invention had an easily loosened hardness with a finger tip, 
and a good ground condition was maintained, while the natural sand was 
completely frozen like ice. 
TABLE 10 
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Present Conventional Cushion Sand 
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Running Good Good (in a wet state) 
Performance Bad (in a dry state) 
Dust-proofness 
No dusting No dusting (in a wet state) 
dusting (in a dry state) 
Draining Good Good 
Property 
Non-Freezing 
No freezing 
Freezes 
Property 
Outflow of None -- 
Coating Material 
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