Note: Descriptions are shown in the official language in which they were submitted.
7 ~
`
This invention relates to a process ~or producing
oil-absorbing materials which are use~ul for collecting oils
flowing on the surface of water or those dispersed in water
as oil particles.
Various types of oil-absorbing materials have pre~iously
been used ~or collecting and removing various oils that have
flowed onto the water surface, for example, the ~lowing of
heavy oils on the surface of the sea. Oil-ab~orbing materials
in general use are structures composed of natural fibers or
synthetic fibers in the form of~ for example~ a ~at or a fence.
Known natural fibers used for th~s purpose include~ ~or example,
grass peat fibers, wood wool7 and straws, and polypropylene
and polyethylene fibers, for example, are known as the synthetic
~iberq .
Since these oil-absorbing materials are evaluated not only
by their ability to absorb oils, but also by their combustibility
after oil absorption, oil-absorbing materials composed of the
natural fibers are preferred to those made of the synthetic fibers.
The oil-absorbing materials of the synthetic fibers melt during
combustion, and it is difficult to burn them o~f. Furthermore;
they produce black smoke or hazardous substances during combustion,
and there~ore, a special combustion Eurnace or special equipment
for the removal of the hazardous substances are required.
On the other hand, since oil-absorbing materials made o~
natural fibers are hydrophilic, they absorb not only oils ~but
8t7'~
also water when put into a water area polluted by oils, and
consequently, their ability to absorb oils is restricted to
not a small extent.
This defect can be overcome to some extent b~ subjecting
the natural fibers to a water-repelling treatment using a
chemical consisting mainly of an emulsion-type water repellent
of, for example, the aliphatic wax or silicone type. However,
when oil-absorbing materials produced from the natural ~ibers
~o treated ~loat on the water surface for long period~ of time
while being tossed abouk in the waves o~ the sea and in contact
with oils, the water-repellent itself is dissolved and removed
out of the oil-absorbing materials so that the water-repelling
effect does not last sufficiently. In addition, the emulsifier,
heavy metal salts, etc. contained in the treating chemicals may
dissolve in the water, and cause adverse effects. Accordingly,
the use of the water-repelling chemicals cannot be an appropriate
measure.
It is an object of this invention therefore to pro~ide a
process -~or producing oil-absorbing materials which rekain the
ability to hold oils in water for long periods o~ time, have
good combustibility after oil absorption, and do not produce
hazardous substances during combuskion.
According to this invention, there is provided a proces~
for producing an oil-absorbing material which comprises mixing
vegetable ~ibers with not more than 35% by weight, based on the
~C~608~7~3
fibres, of a solid ole~in polymer, and heating the resul-
ting mixture to melt the olefin polymer, and thereby
impre~nate the vegetable ~ibres with the molten olefin
polymer.
The vegetable fibres used in this invention
are fibres separated from grass peat, fibres of coconut
shell fibres, flax fibres, straws, and grass fibres.
Examples of the solid olefin polymers used in this inven-
tion are homopolymers or copolymers preferably having a
weight average molecular weight of at least 15,000 of
ethylene, propylene, isobutylene and butene, copolymers
of ethylene with vinyl acetate, acrylic acid, acrylates,
methacrylic acid, methacrylates, and mixtures of these
polymers and copolymers. When olefin polymers having a
molecular weight of less than 15,000 are used, the dura-
bility of the water-repellency of the resulting oil-
absorbing materials is somewhat reduced. Desirably,
these olefin polymers are crystalline. The amount of
the solid olefin polymer is not more than 35% by weight,
2Q preferably 2 to 30% by weight, based on the vegetable
fibres.
Mixing of the vegetable fibres and the solid
olefin polymer is performed, for example, by using a
stirrer or card. Preferably, the solid olefin polymer
is used in -the form of a powder having a size of not
greater than 50 mesh, or fibres having a length of not
more than 10 mm. Water contained in the vegetable fibres
evaporates off during a heating operation, and therefore,
lO~
~ 4
it is not necessary to restrict the moisture content of
the vegetable fibres. The vegetable fibres well mixed
with ~e solid olefin polymer are heated preferably to a
temperature above the melting point of the solid olefin
polymer. This heating results in the melting of the
solid olefin polymer and consequently its impregnation
in the vegetable fibres.
Since the amount of the olefin polymer
impregnated in the vegetable fibres is not more than 35%
by weight, preferably 2 to 30% by weight, the porosity
and surface roughness of the vegetable fibres themselves
remain in the resulting structure. A microscopic obser-
vation of this structure shows that adhesion of fibres
to one another asribable to the impregnated olefin
polymer occurs only to a small extent, and the olefin
polymer does not cover the surface of the vegetable
fibres. Accordingly, the oil-holding ability of the
vegetable fibres themselves is not reduced, and the
olefin polymer once impregnated into the fibres is not
likely to dissolve even during its long-term residence in
water. Thus, a long-las$ing stable water-repellency is
imparted to the vegetable fibres. When the amount o
the olefin polymer exceeds 35% by weight, the wick
effect of the vegetable fibres becomes insufficient
during burning so that the fibres generate a black smoke
and the olefin polymer partly drips from the vegetable
fibres.
The oil-absorbing material obtained by the
~`
~i(38t7~
4a
process of this invention can be used as packed in a
suitable receptacle so as to collect oils dispersed as
oil d~oplets in water. Or it can be press-formed into
a mat-like structure, or further wrapped by a
~`
net to prevent the breakage of -the mat in water, and in this
form, can be used to absorb oils on the water surface. Or
the mat so obtained may be placed on the water sur~ace as an
oil fence with a suitable float so as to use it to pre~ent the
S diffusion of floating oils on the water surface.
According to the process of this invention, there ~an
easily be obtained an oil-absorbing material which has water-
repellency durable for long period~ of time in water~ good
oil~absorbing ability inherent to the vegetable fibers, and
good combustibility after oil absorption, and does not produce
a hazardous substance during combustion.
The following examples illustrate the present inventionO
Tt should be noted that the invention is not limited to these
examples alone
Example 1
Polypropylene powder (lOOg) having a size o~ not greater
than 100 mesh and an average molecular weight of 25JOOO was
added to 1.4 Kg of grass peat fibers (water content 40% by
weight~ obtained by beating grass peat in water and separating
the fibers from the humus. They were thoroughly mixed by a
card. The resulting mixture was maintained in a hot air dryer
at 180C for 15 minutes to melt the polypropylene and impregnate
it in the peat fibers. The resulting polypropylene-impregnated
peat fibers are designated as an oil-absorbing material A.
The above procedure was repeated using 42 g o~ an ethylene/
_ 5 _
~10ti,C~7~L
vinyl acetate copolymer powder (lO~o by weight of vinyl
acetate; melting point 95C) with the heat-meltingtemperature
being maintained at 105C. Thus, grass peat fibers impregnated
with the above copolymer were obtained. These fibers are
designated as an oil-absorbing material B.
When the above procedure was repeated using 42 g of an
ethylene/zinc methacrylate copolymer powder (10% of zinc
methacrylate; melting point 113C) with the heat-melting tem-
perature being maintained at 12~C, grass peat fibers impregnated
with the above copolymer were obtained. These fibers are
designated as an oil-absorbing materi~l C.
Example 2
1.2 Kg of grass peat ~ibers (water content 20% by weight)
obtained by the same method as set forth in Example 1 and
100 g of fibrillated fibers oP polypropylene having an average
molecular weight of ~0,000 with an average fiber diameter of
3 mm were thoroughly mixed in a Henschei mixer. The resulting
mixture was maintained in a hot air dryer at 180C for 15
minutes to melt the polypropyle~e fibers and impregnate them
in the peat fibers. The rssulting polypropylene-impregnated
peat ~ibers are designated as an oil-absorbing material D.
The above procedure was repeated using 48 g of fibrillated
fiber~ of polyethylene ha~ing an average molecular weight of
20~000 with an average fiber length of 2 mm with the heat-
melting temperature being maintained at 140~C. Thus, polyethylene-
a cle f~Ar k
-- 6 --
0~'7'~
impregnated grass peat fibers were obtained. These ~ibers are
designated as an oil-absorbing material E.
; Exam~,l,e 3
0.~ Kg of flax fibers twater content 40%) and 160 g o~
polybutene-l powder having an average molecular weight of
50,000 and a size of not greater than 100 mesh were mixed, and
maintained in a far-infrared furnace at 150C for 15 minute~ to
melt the polybutene-l and impregnate it into the ~lax ~ibers.
The resulting impregnated flax fibers are designated as an oil-
absorbing material F.
Comparative ,Exa,mple
A paraffin wax emulsion having the composition indicated
below was diluted with water, and the same grass peat fibers
as used in Example 1 were immersed in the diluted emulsion.
Then~ the immersed peat fibers ~re squee~ed by rolls to the
desired paraffin wax content, and heated at 100C to melt the
paraffin wax adhering to the peat ~ibers and impregnate it into
the peat fibers. In this manner, products with a paraf~in wax
content of 2% by weight and 4% by weight were obtained. These
'20 products are designated as oil-absorbing materials I and II,
respectively.
~ 7 ~
~10~37~
Formulation_of the para~in wax emulsion
Paraf-~in (m.p. 54 5~C~ 90%
Beef tallow free fatty acid 38.8%
Monoethanolamine 3.35%
Water 48.85%
Com~arative Example 2
A commercially available silicone emulsion for water-
repellent ~inishing o~ textiles (To~hiba TS~ 831) and a
~ commercially available catalyst (Toshiba CW 80~ were mixed in
a volume ratio of 1:1. The same grass peat ~ibers as used in
Example 1 were immersed in the mixture, dried at 100C for 10
minutes, and then heat-treated at 180C for 5 minutes to form
a product having a silicone pick-up o~ 3% by weight based on
the peat ~ibers. The product is designated as an oil-absorbing
materila III.
ComParative Example 3
A waxy substance having an average molecular weight of
6,ooo obtained as a by-product in the production o~ polyethy~ene
was dissolved in naphtha by heating to ~orm a 30% by weight
solution. The same grass peat fibers as used in Example 1 were
immersed in the resulting solution, squeezedg cooled, and then
crumpled to remove the excess o~ the waxy substance and thereby
to obtain a product with a waxy substance pick-up of 150%. The
product is designated as an oil-absorbing material IV.
The above procedure was repeated using a 10% by weight
~ `I rad~ ~Or~S
'7~
solution of the ~axy substance, thereby to obtain a product
having a waxy substance pick-up of 1~ which is designated
as an oil-absorbing material V.
ComParative Example 4
5 ' Atactic polypropylene having an average molecular",`weight
of 10,000 obtained as a by-product in the production of polypro-
pylene was dissolved in toluene by heating to form a 30% by
weight solution of the atactic polypropylene. The same grass
peat fibers as used in Example 1 were immersed in the solution,
and dried in air to remove the toluene and thereby to obtain
a product with an atactic polypropylene pick-up of 100%. The
product is designated as an oil-absorbing material VI.
The above procedure was repeated using a lO~o by weight
toluene solution of the atactic polypropylene thereby to form
a product having an atactic polypropylene pick-up of 10%.
The product is designated as an oil-absorbing material ~II.
ComParative Example 5
- The same procë'dure as in Example 3 was repeated except
that the amount of the polybutene-l added was changed to 220 g.
Thus, flax fibers impregnated with polybutene-l were obtained.
This product is designated as an oil-absorbing material VIII.
Test ExamPle 1 ttest ~or the durability of water rePellenc~)
128 g each of the oil-absorbing materials obtained in
Examples 1 to 3 and Comparative Examples 1 to S was wrapped in
a net made of polyethylene filaments and formed into a square
_ ~ _
0~7'~
mat measuring 40 cm i~ each side and 1 cm in thickness. The
mats obtained were each tested for the durability of water
repellency in the following manner,
The mat was allowed to stand in a water tank in which
waves with a height o~ 30 cm, a length of 200 cm and a ~eriod o~
1.2 seconds were artifieially produced, The time that elapsed
until the mat completely submerged in water was measured.
When the mat did not submerge~ the state of the mat after
per~orming the test ~or 78 hours was obser~ed.
The-same grass peat fiber~ (a) and ~lax fibers (b) as
used in Examples 1 and 3 respectiv ly were also tested in the
same way as above. The results are shown in Table 1.
Table 1
. . _ . . ~
Oil-absorbing Time that elapsed State of the mat after
material until the eomplete the end of the test
submerging of the
__ _ _ mat ~Hours ? ~
A _ Completely floating
B _ Submerged to about 1j8
C _ Submerged to about 1/8
D _ Submerged to about l~lO
E _ Submerged to about l/lO
~5 ~ _ ~ Col Ipletely Ploating
-- 10 --
~8t~
III 38
V 45 Submerged to aobut 3/4
VI _ Submerged to about 1/4
VII 68
VIII Completely ~loating
Test Exam~ple_2~ (test for the abilitY _o~absorb oils and water)
10 g each of the oil-absorbing materials ohtained in
Examples 1 to 3 and Comparative Examples 1 to 5 was wrapped
in a net made of polyethylene ~ilaments and formed into a
square mat measuring 10 cm in each side and 1 cm in thickness.
The mats obtained were each tested for the ability to absorb
oils and water in the following manner.
me mat was ~mmersed ~orcibly in water for a predetermined
period o~ time, and oscillated with an amplitude of 4 cm at
100 strokes/minute. The mat so treated was allowed to stand for
5 minutès so as to remove water, and then put into a waker`tank
in which a ~loating film o heavy oil A with a thickneæs o~
0.5 mm was formed on the water surace to cause it to absorb
the oil, The mat was pulled up from the tank, and al~owed to
stand for 5 minutes. The ~inal contents of the oil and water
in the mat were determined on the basis of the weight of the
mat.
The same grasæ peat fibers (a) and flax fibers (b) as
:`
~lJ16~8~7~
used in Examples 1 and 3 were ,tested in the same way as
above, The results obtained are shown in Table 2,
Table 2
Time for Oil-absorbing Amount of the Amount o~
immersing material oil held by water held
the mat in the mat by the mat
water __ _ _ (~-oil, ~-ma,t) l~,-wa_er/~ at)
A 9.13 0.50
B 9 .51 O .48
. C 9.5 o.55
D 9.55 o.4~
E 9.70 0.40 .
O F 9.38 0.58
(in the dry
state) a 6.58 1,27
, b 7.48 1.71
I 6.13 1.50
II 7.26 1.08
III 7.83 0.95
IV 4.58 o.55
V ~.o6 .59
VI 5,05 0.37
VII 8.59 - 0.56
VIII 8, 23 O . 45
A 9.66 0,70
5 minutes B 9.62 o~73
C 9.00 0.68
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10ti08'74
D 9 . 60 o ~ 7o
E 9.35 0 .65
F 9 .65 0 .59
a 0 .54 7 .34
5minutes b 0 . 63 7 . 2 4
I 6.27 2 .05
II 6 . 66 2 .13
III 7 . 5 0 1 . 24
IV 4.38 o.65
VI 74 5837 l 651
VII 8 . 13 1 . 2 4
VIII 8 .16 0 . 5 6
_ A 9 . 50 0 . 75
B 9 .55 0 .78
C 8.92 0.72
1day D 9.52 0.70
E 9.67 o.66
F 9 38 0.62
b O . 55 8 . 2 2
I 3 .59 5 .3
II 4 . 06 4 . 3 7
III 5 .32 3 .48
IV 4.08 1.19
,,
-13-
~ 8~7~
V 6.47 2,31
VI 4.75 0088
1 day
VII 7.,49 2.05
VIII 8.08 0.70
_ .. ..... _ . _
A 9.22 0.81
B 9.23 0.83
C 8.53 o.85
D 9.15 0.80
E 9.68 0.68
F 9.30 0,71
10 days
a 0.43 8.93
b 0,48 8.35
I 1.15 7.~8
II 1.52 7.11
III 2.19 6.65
IV 3.81 1.86
V 2.89 6.14
VI 4 .Sl 1. 25
VII 3 . 2 6 6.~7
VIII -~.01 o~7~
.. .. _ . . . _
~est_ExamPle 3 (test ~or combustibility)
Mats were produced in the same way as in Test Example
1 using the oil-absorbing màterials obtained in Examples 1
and 3. Each o~ the mats was placed on a wire gauze, and ignited.
The mats made of the o~l-absorbing materials A to F, I to
III, V and VII showed a good burning state without producing
any smoke, But the mat mad~ of the oil-absorbing material VIII
burned while generating some black smoke. The mats made of the
oil-absorbing materials IV and VI produced a large quantity of
black smoke, and a part of the polymer impregnated melted, and
dripped from the wire gauze.
ExamPle_d
2 . 5 ~Cg of the saDu~ grass peat f ibers (water content 40%
by weight3 as used in Example 1 a~d 120 g of a powder with
a size of not greater than 100 mesh of a propylene/ethy~ene
copolymer (ethylene conte~t 10%) ha~ing an average molecular
) weight of 40,000 were mixed, and maintained in a hot air oven
at 160C for 15 minutes to melt the polymer and impregnate
it into the peat f iber~ . The resulting oil-absorbing ma~eria~
was packed into a cylindrical receptacle haYing a diameter of
260 mm and a height sf 400 mmO Water having su~pended therein
40 ppm o~ a lubricating oil a~ ~ine particles was ~lowed at a
rate of 700 liters/hour through the receptacle. Even after the
pas~age of 15~ hours, the oi~d content at the exit o~ ~he
) receptacle did not exceed 5 ppm.
xam~le 5
200 g of a polyethylene powder having a size of not
greater than 100 mesh and an a~erage molecular weight of
18,000 was added to 1.4 Kg of coconut shell fibers (water
- 15 -
8'7~
content 40% by weight), and they were thoroughly mixed by
a Henschel mixer. The resulting mixture was hok-pressed a-t
125C, and maintained for 15 minutes in a compre~sed sta$e
such that lO g o~ the mixture was converted to a ~quare mat
measuring 10 cm in each side and l cm in thickness. Thus,
a mat composed of the coconut shell fibers impregnated with
the molten polyethylene (oil-absorbing material G) was
obtained. The mat was tested for its abilit~ to absorb oils
and water:~in the same way as in Test Example l using heavy
oils B and C. The results are shown in Table 3.
For comparison) a square mat measuring lO cm in each
side and 1 cm in thickness was made rom lO g of non-tr~ated
coconut shell ~ibers tc), and its ability to absorb water and
oils was test~,d in the same wayO The resul$s are also shown
in Table 3.
Table 3
Time for Oil-absorbing Type of Amount of oil Amount o~
immersing material heavy held by the water held
the mat oil mat (g-oil/ by the mat
in wate~. .- g-mat) (g-water/
_ _ ~-mat)
O G B 8.73 0,30
~in the dry
state)- C 11,53 0.28
C B 6.50 1,03
_ _ . _ C 9.85 0.97
G B 8,62 o,65
~ C 11:,08 o.56
10 days _ _
___ _ C _ ~ 2 53 7 5
- 16 -
lO~B74
The above mats were subjected to the same test for
th0 durability of water repellency as in Test Example 1.
As a result, the mat prepared from the oil-absorbing
material G submerged to a depth of only about l/lO, but the
mat prepared from the oil-absorbing material C completely
submerg0d in 12 hours.
After the test for the ability to absorb oils and
water, the mat prepared from th~.oil-absorbing material G
showed a good burning state without the generation o~ any
black smoke.
Test Exam~le A (test for the ability to absorb a fish oil~
A square mat measuring lO cm in each side and 1 cm in
thiokness was made from lO g of the oil-absorbing material B
in the same way as in Test Example 2, and tested for its ability
to absorb a sardine oil and water in the same way as in
Example 2. The results are shown in Table 4.
Table 4
. _ . _ __ . . ........... .
Time for Amount of the Amount of water
immersing sardine oil held by the mat
the mat held by the (g-water/g-mat)
in water mat ~g-oil/
_ _ ~-mat) .
in the 8.79 1.05
dry state~
_ . . _
5 minutes 8.26 1.24
. .
4 days 7.95
- 17 -
