U.S. patent application number 10/381573 was filed with the patent office on 2004-01-22 for structure that counteracts biofouling in aquatic environments.
Invention is credited to Jonsson, Per, Winberg, Ragnar.
Application Number | 20040011268 10/381573 |
Document ID | / |
Family ID | 20281506 |
Filed Date | 2004-01-22 |
United States Patent
Application |
20040011268 |
Kind Code |
A1 |
Jonsson, Per ; et
al. |
January 22, 2004 |
Structure that counteracts biofouling in aquatic environments
Abstract
The invention aims at a structure which counteract bio-fouling
in aquatic environments and is principally characterized by the
fact that the surface of an object has parallel ribs projecting
from it (4, 5), close to each other, which are narrowing outward
and whose height is less than two millimetres.
Inventors: |
Jonsson, Per; (Stromstad,
SE) ; Winberg, Ragnar; (Helsingborg, SE) |
Correspondence
Address: |
Rolf Fasth
Fasth Law Offices
629 E Boca Raton Road
Phoenix
AZ
85022
US
|
Family ID: |
20281506 |
Appl. No.: |
10/381573 |
Filed: |
March 25, 2003 |
PCT Filed: |
October 15, 2001 |
PCT NO: |
PCT/SE01/02229 |
Current U.S.
Class: |
114/222 |
Current CPC
Class: |
B63B 59/04 20130101;
B08B 17/065 20130101 |
Class at
Publication: |
114/222 |
International
Class: |
B63B 059/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 18, 2000 |
SE |
0003815.8 |
Claims
1. Structure that counteracts biofouling in aquatic environments,
characterized by the fact that the surface of an object has ribs
projecting from it, situated close to each other (4, 5), which are
narrowing outward and whose height is less than two
millimetres.
2. Structure according to Patent claim 1, characterized by the fact
that each rib has a cross-section in the main triangular with the
angles at the base larger than 70 degrees.
3. Structure according to an earlier patent claim, characterized by
the fact that the ribs are made from a foil which is meant to be
glued on the object which is to be protected.
4. Structure according to Patent claim 3, characterized by the fact
that the foil on its inside has a carrying layer of other material
than the foil and where the carrying layer is meant to be glued on
the object which is to be protected.
5. Structure according to Patent claim 1, characterized by the fact
that it is made with a cold or warm tool directly on the surface of
the object which is to be protected.
6. Structure according to Patent claim 1, characterized by the fact
that it is made by chemical etching directly on the surface which
is to be protected.
7. Structure according to Patent claim 1, characterized by the fact
that it is made by chemical etching on a foil which is glued on the
object which is to be protected.
8. Structures according to Patent claim 1, characterized by the
fact that it is made on pipes by extrusion.
Description
[0001] This invention has reference to counteracting bio-fouling on
surfaces in aquatic environments by letting the surface have a
ribbed structure.
[0002] Surfaces which are immersed into the sea will immediately be
covered by bio-fouling. First a thin layer of bio-polymers,
bacteria and unicellular algae is formed, followed by a thick layer
of invertebrates for instance acorn barnacles and mussels. Such
bio-fouling is a serious problem for shipping because the increased
water resistance has an influence on the fuel consumption. Besides
bio-fouling has negative consequences for flows through piping
systems and for exchange speeds in heat exchangers. The marine
cultivation industry is also affected negatively by bio-fouling.
Net bags, cultivation cages, rafts and ropes will often be strongly
overgrown which will cause increased mortality and high cleaning
costs. Increased weight and cleaning as a result of bio-fouling are
also problems within offshore industry.
[0003] The most frequent method to counteract bio-fouling is
applying poisonous paints to the surfaces which are to be
protected. Commercial shipping often uses TBT paints (Tributyltin)
and pleasure boats in most cases copper-based paints. Increased
environment-consciousness of the risk of spreading these very
poisonous substances in the sea has resulted in local prohibitions
against their use. Moreover a global restriction against the use of
TBT paints for commercial shipping is expected to come into force
in 2008.
[0004] The need of new environment-friendly solutions to prevent
bio-fouling is obvious. On the Swedish west coast for instance the
dominating problem is acorn barnacles. One method which does not
include any chemical substances to reduce bio-fouling by acorn
barnacles is providing surfaces with microstructures. In repeated
experiments it has been observed that the larvae of acorn barnacles
avoid surfaces with structures of a certain appearance. The
mechanism is that the adhesion of the larvae is disturbed and
interrupted and that the larvae actively choose to abandon the
surface. Existing inventions which give this effect is providing
surfaces with fibres which are glued at right angles out from the
surface. Other existing methods are attaching a carrying layer of
cloth with projecting fibres from the cloth or attaching a plastic
film with thin plastic strips welded to it.
[0005] The invention has the special characteristics which are
evident from the patent claims and will be explained more closely
in the following by means of figures where examples are shown.
[0006] FIG. 1 shows a section of a foil greatly magnified.
[0007] FIG. 2 shows, greatly magnified, a ribbed structure directly
on a surface which is to be protected.
[0008] 1 indicates a carrying foil of plastic with a high
melting-point. This foil is laminated with a second foil 2 of a
more easily fusible plastic. 3 indicates a self-adhesive glue. From
the easily fusible plastic a big number of ribs 4 run out. At the
base they can be for instance 0.15 millimetres wide and one
millimetre high. They have an outward narrowing form. The ribs are
placed close to each other in parallel rows. The ribs have a
rounded transition at the base.
[0009] After manufacturing the foil can be rolled on rolls.
Protective paper which can be pulled off is not necessary since the
edges of the ribs reach the self-adhesive layer when rolled up.
[0010] Instead of a self-adhesive glue, the inside can consist of a
non-woven material which is well fastened to the carrying foil. The
non-woven material can easily be glued and in this case it is the
intention that the object which is to be protected or the foil can
be provided with glue and that after that the foil is pressed on to
the object. If the foil is to be suitable for small boats, for
instance pleasure boats of plastic where the surface of the hull is
strongly curved, the foil can be a little elastic, which many
plastics allow. In order to prevent air-bubbles between the hull
and the foil, the foil can be perforated.
[0011] The production of the foil can be made so that a laminate of
carrying foil of not thermoplastic material or of a plastic with a
high melting point is laminated with a thermoplastic with a low
melting point. The laminate is heated and pressed against a
rotating cylinder provided with many grooves in which plastic
material is pressed out and forms ribs. After the plastic has come
into the grooves the plastic is cooled and when the carrying foil
is rolled off from the cylinder the ribs leave the grooves.
[0012] It is possible to make a foil with projecting narrowing ribs
also in other ways, for instance by chemical etching.
[0013] It is evident that the foil can be given various shapes with
regard to the use of material, the distance between the ribs,
height, thickness, inclination and cross-section of the ribs.
[0014] If the foil is strong it is possible, after long use, to
pull off the foil from a hull.
[0015] Unlike attaching loose fibres to a surface where many fibres
are slanting and the distance between the fibres is not controlled,
the ribs can be made to be at right angles to the surface and with
an equal distance between them. Because the ribs are made by
pressing from a foil they are safely connected with it and cannot
come loose. Owing to the outward narrowing form they are strong and
owing to the open form the foil can be easily cleaned.
[0016] In FIG. 2 the ribs are indicated by 5, They were made
directly on a hull 6. This can be made by rolling a cylinder of
adjacent round razor blades under pressure against the surface
which has first been smeared with the material which is to form the
ribs. The rolling can be made with a cold cylinder on a polymer
which has not had time to harden or with a heated cylinder on a
hardened polymer.
[0017] On ships the ribs should be parallel with the surface of
water to make friction against the water low. This direction also
gives the best anti-fouling effect since it disturbs the wandering
of the larvae towards the light.
[0018] Experiments have been made with a rib structure where the
angles at the base were 79 degrees. This surface reduced the
fouling of acorn barnacles with 98 per cent compared with a smooth
control surface.
[0019] A great height of the ribs affects the friction against the
water negatively. For stationary objects for instance off-shore and
sea breeding the height of the ribs is of little importance.
[0020] For pipes longitudinal ribs inside and outside can be made
by extrusion.
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