EP0707680A1

EP0707680A1 - Method and materials for coating of surfaces

Info

Publication number: EP0707680A1
Application number: EP94921144A
Authority: EP
Inventors: Jarl-Erik Rollen
Original assignee: ROLLEN JARL ERIK
Current assignee: ROLLEN JARL ERIK
Priority date: 1993-07-06
Filing date: 1994-07-01
Publication date: 1996-04-24
Also published as: SE9302322L; AU7197494A; SE501492C2; SE9302322D0; WO1995002098A1

Abstract

Method and material compound for coating of surfaces with a porous material, preferably a cold-insulating and condensation-preventing and/or smell-absorbing coating, whereby the porous material/material compound is sprayed in the shape of granules/powder on said surface and mixed with a binder during the spraying. The material compound includes a porous material/material compound, which is constituted by granules and by one or more porous material, at least one of these having a bulk density of highest 150 kg/m3, a binder which can be a powder or be dispersed or dissolved in a liquid, and eventual additives. The porous material/material compound constitutes more than 15 % (percentage of weight) of the wet material compound at applying on the surface which is to be coated.

Description

METHOD AND MATERIALS FOR COATING OF SURFACES

TECHNICAL FIELD

The present invention concers a method for coa- ting of surfaces with a porous, sorbating material/com¬ pound, called "porous material" below, prefarably a ther- mically insulating and condensation-preventing coating and a material for this coating. BACKGROUND TECHNICS It is among others by the Swedish patent publi¬ cation SE-C-387 681 known to protect a surface from con¬ densation by a compound consisting of a porous material with a bulk density of maximum 150 kg/m³ kept together by a binder including different substances. In the finished product it is only the porous material which gives the compound its condensation-preventing characteristics. The binder only has the object to keep the porous material on the surface which is to be prevented from condensation. In order to give the compound the biggest possible sorba- tion capability the deal of binder in relation to the deal of the porous material must be kept low. This will give the finished compound an extremely high pigment volume concentration (PVK). A high PVK-number always will leed to a lot of problems. The rheology of the product will be difficult to control, which makes it to a product which is very difficult to handle. Especially at indust¬ rial use the consistence of the compound will be a problem.

In the patent publication SE-C-387 681 it is mentioned that the porous material can vary between 5 and 20 % in the wet compound of materials. However experien¬ ces have shown that amounts of porous material of 15 % and more will make the compound of materials so dry that it can not be applied in a normal way, e.g. sprayed on a surface. The amount of porous material in itself can be increased provided that it is stirred and disintegrated during the mixing in of the same, but this will give a coating which is considerably less porous and which by that will become deteriorated characteristics. Thus the technics described in Se-C-387 681 only are valid for amounts of porous material up to 15 %. During transportation the consistence and homo- genousity of the compound will be changed, why it need to be agitated before it will be used. Thereby the porous material partly will be disintegrated and loose a part of its condensation-preventing capability. As a rule the application is carried out by means of sprayers for com¬ pressed air or high-pressure sprayers. Because of the high PVK-number the compound is difficult to pump and it has a tendency to stick in nozzles with production dis- turbings as a consequence. The drying and hardening pro- cess also will be complicated. The main part of the li¬ quid in which the keeping binder is dispersed or dis¬ solved, is sorbated during the time of storage of the porous material. At the drying process the liquid first have to be driven out of the pores to be able to evapo- rate. This causes that the real energy consumption will be considerably higher than the theoretical. In a convec¬ tion oven it is a great risk that the heat will drive the liquid into the pore system, making a risk for appearance of skin and blisters demanding special control systems for the oven. A consequence of the risk for appearance of skin is that water-based binders demand extra dissolving agents to keep the surface open. These dissolving agents have a higher boiling point than water and consequently demand more energy to be removed. Besides they also con- stitute an undesired influence on the environment.

Also the characteristics of the product itself are deteriorated at the present manufacturing method. The only function of the binder is to bind the porous gra¬ nules to each other into a porous lattice and to bind this lattice to the surface which is to be condendation- protected. However a big part of the binder is soaked into the porous material where it has no function. In order to compensate this the finished compound must con¬ tain more binder but wat is demanded to give the conden¬ sation-protecting coating a good adherence to the treated surface. On the same time the sorbation-capability of the porous material will be reduced as the pores partly are filled with binder and eventually other additives. DESCRIPTION OF THE INVENTION

The purpose whith the present invention is to bring about a method for coating of surfaces with a po- rous material, preferably a thermically insulating and condensation-preventing coating, and a material for this coating to be used at practising of the method. The me¬ thod according to the invention is characterised in that the porous material is sprayed in the shape of granules or powder on said surface and mixed with a binder during the spraying. The compound of materials which is sprayed and which is constituting the coating in question compri¬ ses a porous material with a bulk density of highest 150 kg/m³ and a binder which can be a powder or which can be dispersed or dissolved in a liquid. The material compound according to the invention is characterised in that the porous material constitutes more than 15 % (percentage of weight) of the material compound at application on the surface which is to be coated. More details and characteristics concering the method respectively the material compound according to the invention will be clear from the description below and from the claims.

It is per se known to bring about a coating on a surface by spraying powder on the surface, but this as a rule concerns materials which are easy to transport in closed conduits, e.g. powder dye stuff. A porous material with the low bulk density which is demanded in the pre¬ sent case is very difficult to transport in closed con- duits. Because of its surface structure the material tends to stick at the smallest restriction in the trans¬ port system. These materials also have a strong tendency to raise dust which makes it impossible to spray this material only from a nozzle. However it has surprisingly been proved that a very small fluidizing of the material in a section where it has a tendency to stick is suffi- cient in order to get a steady flow in the entire, closed transport system also by use of conventional pumps such as diaphragm and hose pumps. The fluidizing gas also can be given such a pressure that it also can be utilized for the transportation of the porous material. However the main problem is to get the very light material to fall down fast enough on the surface which is to be coated. Another problem has been to get a sufficiently good mix¬ ture between the porous material and the binder which shall keep the porous material in a lattice and attend to the adhesion to the base surface.

However experiments have shown that the porous material can be forced out from the nozzle in a helical movement in the air in front of each nozzle by means of a sprayer and the very pressure which is demanded for the fluidizing/transport and/or by means of more air. These nozzles are mentioned "powder nozzles" below and are mainly centrally located in the nozzle device.

At each powder nozzle one or more outer liquid nozzles are arranged, from which binder is sprayed by means of air or high pressure. These outer nozzles are placed in that way that they mainly surround the powder nozzles and showing a tangential spraying direction rela¬ tive to the main spraying direction of the device, which causes that the binder, atomized by the pressure, will surround the porous material in a helical movement making the porous material and the binder to mix effectively in the air before reaching the surface which shall be coa¬ ted. On the same time a control of the light porous mate¬ rial is achieved contributing to a completely even coa- ting on the surface.

By means of a flow meter the proportions between the porous material and the binder can be variably varied. It has surprisingly been prooved that the mixing proportion between the porous material and the binder can vary between 1,5:1 and 9:1 giving sufficient properties regarding condensation protection and durability. The mixing proportion 1,5:1 gives a higher durability but lower condensation preventing proporties, whilst the mix¬ ing proportion 9:1 gives very good condensation preven¬ ting proporties but a lower durability.

Further an advantage with the method according to the invention is its flexibility. It is e.g. simple to vary the binder in that way that it fits for the base surface which is to be coated. By not mixing the porous material whith the binder until after the spray nozzles or in any of those one will be independent of the choice of binder. By e.g. using more transport hoses for the binder it is possible to use binders which are constitu¬ ted by two or more components in order to thereby lower the hardening time for the coating. The production method gives the same flexibility regaring the choice of harde- ning method. Each user therefore can choice if he likes to have physical or a chemical hardening, convection oven, IR-oven, frequency oven, microwave oven etc. By adding different additives as well as by mixing different porous material a product will be achieved which also is fire-protecting, mould-retarding, bacteria-retarding and smell-removing and which also by means of a suitable pig¬ ment can be given a desired colour. The porous, sorbating material also can be pre-treated with a wetting agent, which increases the sorbating capability of the finished coating.

To sum up the method and the belonging material mixture according to the characteristics, mentioned in the claims, mean that the former drawbacks at the coating of surfaces according to the method and the material com- pound which is described in the Swedish patent publica¬ tion SE-C-387 681 have been set aside. As the technics according to the present invention also gives a considerably better utilization of material the present coating of surfaces can be achieved at a considerably lower cost.

Claims

1. Method for coating of surfaces with a porous material, preferably a cold-insulating and condensation- preventing and/or smell-sorbating coating, c h a r a c - t e r i z e d in that the porous material/material com¬ pound is sprayed in the shape of granules or powder on said surface and mixed with a binder during the spraying.

2. Method according to claim 1, c h a r a c ¬ t e r i z e d in that the porous material/material com- pound respectively the binder is caused to escape from one or more nozzles and after that to mix before the ma¬ terial compound reaches the surface which will be coated.

3. Method according to claim 1, c h a r a c ¬ t e r i z e d in that the porous material/material com- pound respectively the binder is caused to mix next be¬ fore the material compound is caused to escape from a common spraying nozzle.

4. Method according to claim 1 or 2, c h a ¬ r a c t e r i z e d in that the binder is given a heli- cal movement, surrounding the porous material/material compound as these materials leave a spray nozzle (-nozz¬ les), that eventually also the porous material/material compound per se is given a helical movement, and that the binder thereby is mixed with the porous material/material compound.

5. Method according to any of the claims 1-4, c h a r a c t e r i z e d in that the porous material/ material compound is transported to the spray nozzle (-nozzles) in a fluidized shape.

6. Material compound for making a coating by using the method according to any of the preceding claims, including a porous material/material compound constituted by granules and by one or more porous mate¬ rial, at least one of these having a bulk density of highest 150 kg/m³, a binder which can be a powder or be dispersed or dissolved in a liquid, and eventual additi¬ ves, c h a r a c t e r i z e d in that the porous material/material compound constitutes more than 15 % (percentage of weight) of the total material compound at applying on the surface which shall be coated.

7. Material compound according to claim 6, c h a r a c t e r i z e d in that the porous material/ material compound constitutes maximum 80 % (percentage of weight), preferably 15 - 50 % (percentage of weight), and especially 15 - 25 % (percentage of weight) of the total material compound.

8. Material compound according to claim 6 or 7, c h a r a c t e r i z e d in that the mix proportion between the porous material/material compound and the binder varies between 1,5:1 and 9:1, preferably between 1,5:1 and 5,6:1 and especially between 1,5:1 and 2,8:1.