Method and device for preventing gas uptake in a resin in a storage tank

Abstract

 A method for preventing gas uptake in a resin (5) in a storage tank (1) is described. It comprises the step of inserting a displacement system (10, 20) in the tank (1) for avoiding that the surface (6) of the resin (5) in the tank (1) comes in contact with the gas (7). Moreover, a device for preventing gas uptake in a resin (5) in a storage tank (1) is disclosed, which comprises a displacement system (10, 20) for inserting the displacement system (10, 20) in the tank (1) for avoiding that the surface (6) of the resin (5) in the tank (1) comes in contact with the gas (7).

Description

Field of the Invention

[0001] The present invention relates to a method and a device for preventing gas uptake, especially air uptake, in a resin in a storage tank. It further relates to a resin storage tank.

Background of the Invention

[0002] Fibre reinforced plastic composites are used in a variety of technical products such as cars, wind turbine blades, storage tanks etc. The composite material consists of a plastic matrix and a plurality of reinforcing fibres. Often the so-called vacuum-assisted resin transfer method, named VARTM, is used to infuse the liquid resin material that forms the matrix material when cured. As vacuum is applied to the resin and fibres in the mould cavity, even very low contents of mixed-in air or gas will expand greatly and form air voids, which may impair the quality of the final product.

[0003] The transportation of the liquid resin often takes place in standard pallet storage tanks, called IBC's, or it may be transported in road tankers. During transport from the resin manufacturer to the end user, the resin is exposed to excessive movements that can make waves on the surface of the resin. These movements can increase the uptake and dissolving of air into the resin in the tank. Often transportation takes place at temperatures below 20°C at which temperature the viscosity of the resin is higher, and the ability to mix-in and include air bubbles is higher, due to the higher viscosity of the fluid.

[0004] In order to reduce the air content of resins, a degassing facility of considerable costs in purchase and operation is often used. To reduce the air content, the degassing units normally heat up the resin and apply high vacuum. A considerable amount of energy is thus used for the degassing operation.

Description of the Invention

[0005] It is therefore an objective of the present invention to provide an advantageous method and a device for preventing gas uptake in a resin in a storage tank.

[0006] This objective is solved by a method for preventing gas uptake in a resin in a storage tank, as claimed in claim 1, a device for preventing gas uptake in a resin in a storage tank, as claimed in claim 9 and by a resin storage tank, as claimed in claim 14. The dependent claims define further developments of the present invention.

[0007] The inventive method for preventing gas uptake , especially an air uptake, in a resin in a storage tank comprises a step of inserting a displacement system in the tank. The displacement system acts as means for avoiding that the surface of the resin in the tank comes in contact with the gas, especially with the air. The inventive method may further comprise the step of filling the tank with resin, which can be done before or after inserting the displacement system in the tank.

[0008] The inventive method has the advantage, that by inserting the displacement system in the tank a contact between the resin surface and the air is avoided, which reduces the possibility of the occurrence of air or gas bubbles in the resin during transportation. Consequently, the gas or air content in the resin after transportation is reduced or avoided.

[0009] A simple total filling of the tank volume is not possible, as the thermal expansion of the resin could expose the closed tank system to excess loads. By inserting the displacement system in the tank, according to the present invention, a total filling of the tank volume is possible, since the displacement system may be compressible and hence avoid excess loads within the closed tank system.

[0010] Generally, a pallet storage tank, an IBC tank, or a road tanker can be used. Moreover, a displacement system may be used, which is part of a tank lid or tank cap. Additionally or alternatively a displacement system may be used, which is part of a means for filling resin into the tank. For example, the displacement system can be part of a standard IBC tank lid or cap, through which the tank can be filled safely.

[0011] A displacement system may be inserted, which comprises an expandable or expanding and/or pressurisable or pressurized displacement body. The expandable or pressurisable displacement body can prevent the resin from coming in contact with the gas, for example with the air, when stored in the tank.

[0012] Furthermore, a displacement system may be inserted, which comprises a balloon or bladder. Such displacement system can be inserted into the resin and the balloon or bladder can be filled with gas, for example with air. The balloon or bladder can be immersed in the resin. For instance, the balloon or bladder can be filled with a gas, for example air, until the surrounding resin fills up the tank to the top. As a result no air is left over the resin surface in the tank.

[0013] A cap or lid comprising the displacement system can be placed on top of the tank after filling the tank with resin. A combination of a tank cap or lid with the displacement system has the advantage, that a compact, simple and cheap device for performing the inventive method is provided.

[0014] Furthermore, a displacement system can be used, which comprises a cylinder with a closed bottom end. The cylinder can be immersed in the resin through a hole in a cap of the tank. The resin can be replaced by pressing the cylinder into the resin, for example by pressing the cylinder downwards, until the resin replaces the air or other gas above the resin surface. Advantageously, the cylinder can be forced into the resin or forced downwards by a spring, for example a compression spring, especially a coil spring.

[0015] In a further variant, a displacement system can be used, which comprises a spring loaded cylinder. The spring loaded cylinder may comprise a one way valve at the bottom end of the cylinder. The one way valve may for example be a spring loaded ball one way valve. The resin can be filled into the tank using the spring loaded cylinder as filling tube.

[0016] Moreover, a tank cap or tank lid may be used, which comprises a one way valve. The one way valve may allow the escape of gas or air from the tank, but does not allow resin to pass the valve.

[0017] The inventive device for preventing gas uptake in a resin in a storage tank comprises a displacement system for inserting the displacement system in the tank. The displacement system may be insertable into the tank for avoiding that the surface of the resin in the tank comes in contact with the gas, for example with the surrounding air. The inventive device has generally the same advantages as the previously described inventive method.

[0018] Advantageously, the inventive device may additionally comprise a means for filling the tank with resin. Preferably, the means for filling the tank with resin may be incorporated into the displacement system.

[0019] The storage tank may be a pallet storage tank, for example an IBC tank, or a road tanker.

[0020] The displacement system may be part of a tank lid or a tank cap. Moreover, the displacement system may be part of a means for filling resin into the tank. Preferably, the displacement system may comprise an expandable and/or pressurisable displacement body, for example for preventing the resin from coming in contact with the gas or air.

[0021] The displacement system may comprise a balloon or bladder. Moreover, the displacement system may comprise a cylinder, for instance with a closed bottom end. For example, the cylinder can be immersed in the resin through a hole in a cap of the tank and the resin can be replaced by pressing the cylinder into the resin until the resin replaces the air above the resin surface. Advantageously, the displacement system comprises a means for forcing the cylinder into the resin. The means for forcing the cylinder into the resin may be a spring, for example a compression spring, especially a coil spring.

[0022] The displacement system may comprise a spring loaded cylinder, which comprises a one way valve at the bottom end of the cylinder. The one way valve may be a spring loaded ball one way valve. Advantageously, the spring loaded cylinder comprises a filling tube or acts as filling tube for inserting resin into the tank.

[0023] The inventive resin storage tank comprises a device for preventing gas uptake in a resin in the storage tank as previously described. Generally, the inventive resin storage tank has the same advantages and properties as the previously described method and device for preventing gas uptake in a resin in the storage tank.

[0024] The inventive storage tank may comprise a tank cap or tank lid. The tank cap or tank lid may comprise a one way valve, which allows the escape of gas, for example of air, from the tank, but does not allow resin to pass the valve. This valve can consist of a ball, which is made of a material having a density that is higher than air, but lower than the density of the resin. When the resin surface comes to the top, the ball will be lifted by the resin, and thus block the hole over the ball.

[0025] The present invention has the advantages, that mixing-in of air is avoided throughout transportation of the resin. A costly degassing of the resin is not necessary. The quality of the end product is improved and the cost of the end product is reduced.

Description of Embodiments

[0026] Further features, properties and advantages of the present invention will become clear from the following description of embodiments in conjunction with the accompanying drawings. The embodiments do not limit the scope of the present invention which is determined by the appended claims. All described features are advantageous as separate features or in any combination with each other.

Figure 1

schematically shows an IBC pallet tank with resin in a sectional view.

Figure 2

schematically shows an inventive resin storage tank in a sectional view.

Figure 3

schematically shows an inventive resin storage tank in a sectional view.

Figure 4

schematically shows a cap with a cylinder usable for filling an IBC tank in a sectional view.

Figure 5

schematically shows a cap with an air exhaust facility in a sectional view.

[0027] Figure 1 schematically shows an IBC pallet tank with resin in a sectional view. The IBC tank 1 is filled with resin 5. The tank 1 is closed with a cap 2. At the upper surface 6 of the resin 5 ripples or waves 3 occur during transportation of the tank 1. Caused by the ripples or waves 3 and the existence of air 7 above the resin 5 in the tank 1, air bubbles 4 occur within the resin 5.

[0028] Figure 2 schematically shows an inventive resin storage tank 1 in a sectional view. The storage tank 1 is filled with resin 5 and comprises a device for preventing gas uptake in a resin 5 in the tank 1. The displacement system 10 as shown in Figure 2 is a bladder system. It comprises a bladder 11 and a tube 12 for filling the bladder 11. The volume of the bladder 11 depends on the pressure of the gas or liquid which is filled into the bladder 11. Preferably, the bladder 11 can be filled with air via the filling tube 12. By filling the bladder the resin 5 in the tank 1 is displaced such that air at the upper surface of the resin 5 is pressed out of the tank 1. Thus, a complete filling of the tank with resin is achieved.

[0029] Figure 3 schematically shows an inventive resin storage tank in a sectional view. The storage tank 1 is filled with resin and comprises a displacement system 20. The displacement system 20 consists of a cylinder 8. The cylinder 8 is inserted into the resin filled tank 1 to press air or gas in the tank 1 out of it. The cylinder 8 comprises a closed bottom end 9.

[0030] The displacement systems 10 and 20 shown in Figure 2 and Figure 3 are part of the tank cap 2. Generally, the displacement system can be inserted into the resin 5 before or preferably after filling the tank 1 with resin 5.

[0031] Figure 4 schematically shows a cap 2 with a cylinder 8 usable for filling an IBC tank 1 in a sectional view. The cap 2 comprises a hole 13, which is preferably concentrically located in the cap 2. The cylinder 8 is placed within the hole 13. The cylinder 8 may be movable along the centre line 14 of the cap 2 and/or the cylinder 8.

[0032] A compression spring, for example a coil spring 15, is located between the lower surface 23 of the cap 2 and a protrusion 21 at the outer surface 22 of the cylinder 8. The compression spring 21 forces the cylinder 8 into the resin and avoids the cylinder 8 from escaping from the hole 13.

[0033] The cylinder 8 comprises an inner surface 24 and an outer surface 22. At the inner surface 24 a seat 16 for a valve ball 17 is located. A compression spring, for example a coil spring 18 presses the valve ball 17 at the seat 16.

[0034] In the example shown in Figure 4 the resin 4 can be filled into the tank 1 via the tube 19 within the cylinder 8. The pressure of the resin during the filling process presses the valve ball 17 downwards and allows the resin to pass the valve. The air in the tank can escape through the valve ball 17. When the tank 1 is completely filled with resin, the valve ball 17 is pressed against the seat 16 and blocks the hole 19 over the ball 17 so that the resin cannot flow out of the tank 1.

[0035] Figure 5 schematically shows a cap 2 with an air exhaust facility in a sectional view. The cap 2 comprises a hole 25 which also acts as top seat for a floating valve ball 26. The schematically shown cylinder 8 can be a cylinder as shown in Figure 3 or a cylinder as shown in Figure 4. When pressing the cylinder 8 into the resin 5 and/or when filling the tank 1 with resin 5 the air 7 in the tank 1 can escape from the tank 1 through the hole 25 as schematically indicated by an arrow 27. When the tank 1 is completely filled with resin 5, then the ball 26 is pressed against the top seat and hole 25 and prevents the resin 5 from flowing out of the tank 1.

[0036] Generally, the IBC tank or road tank 1 can be filled to the top, and an air filled expansion bladder 11 can be integrated in the cap 2, to allow for thermal expansion of the resin 5 without damage to the tank. The IBC tank or road tank can be filled to the top, and a spring loaded cylinder, placed in the cap, can move outward from the cap, to allow for thermal expansion of the resin or other liquid in the tank.

Claims

1. A method for preventing gas uptake in a resin (5) in a storage tank (1),
characterised in
inserting a displacement system (10, 20) in the tank (1) for avoiding that the surface (6) of the resin (5) in the tank (1) comes in contact with the gas (7).

2. The method as claimed in claim 1,
characterised in
using a displacement system (10, 20) which is part of a tank lid or tank cap (2) and/or part of a means for filling resin into the tank (1).

3. The method as claimed in claim 1 or claim 2,
characterised in
inserting a displacement system (10, 20) which comprises an expandable and/or pressurisable displacement body (11).

4. The method as claimed in any of the claims 1 to 3,
characterised in
inserting a displacement system (10, 20), which comprises a balloon or bladder (11), into the resin (5) and filling the balloon or bladder (11) with gas.

5. The method as claimed in claim 4,
characterised in
immersing the balloon or bladder (11) in the resin (5) and filling the balloon or bladder (11) with a gas until the surrounding resin (5) fills up the tank (1) to the top.

6. The method as claimed in any of the claims 1 to 5,
characterised in
placing a cap (2) or lid comprising the displacement system (10, 20) on top of the tank (1) after filling the tank (1) with resin (5).

7. The method as claimed in any of the claims 1 to 6,
characterised in
using a displacement system (10, 20) which comprises a cylinder (8) with a closed bottom end (9), immersing the cylinder (8) in the resin (5) through a hole (13) in a cap (2) of the tank (1) and replacing the resin (5) by pressing the cylinder (8) into the resin (5) until the resin (5) replaces the air (7) above the resin surface (6).

8. The method as claimed in any of the claims 1 to 7,
characterised in
using a displacement system (10, 20) which comprises a spring loaded cylinder (8), which comprises a one way valve (17) at the bottom end (9) of the cylinder (8), and filling the resin (5) into the tank (1) using the spring loaded cylinder as filling tube (19).

9. A device for preventing gas uptake in a resin (5) in a storage tank (1),
characterised in that
it comprises a displacement system (10, 20) for inserting the displacement system (10, 20) in the tank (1) for avoiding that the surface (6) of the resin (5) in the tank (1) comes in contact with the gas (7).

10. The device as claimed in claim 9,
characterised in that
the displacement system (10, 20) is part of a tank lid or tank cap (2) and/or part of a means for filling resin into the tank (1).

11. The device as claimed in claim 9 or claim 10,
characterised in that
the displacement system (10, 20) comprises an expandable and/or pressurisable displacement body.

12. The device as claimed in any of the claims 9 to 11,
characterised in that
the displacement system (10, 20) comprises a balloon or bladder (11) and/or a cylinder (8).

13. The device as claimed in any of the claims 9 to 12,
characterised in that
the displacement system (10, 20) comprises a spring loaded cylinder (8), which comprises a one way valve (17) at the bottom end (9) of the cylinder (8).

14. A resin storage tank (1) comprising a device for preventing gas uptake in a resin (5) in the storage tank (1) as claimed in any of the claims 9 to 13.

15. The resin storage tank (1) as claimed in claim 14,
characterised in that
the storage tank (1) comprises a tank cap (2) or lid comprising a one way valve (26), which allows the escape of gas (7) from the tank (1), but does not allow resin (5) to pass the valve (26).

Drawing