WO1989010906A1

WO1989010906A1 - Plaster, a method of preparing said plaster and a device for the application thereof

Info

Publication number: WO1989010906A1
Application number: PCT/DK1989/000105
Authority: WO
Inventors: Ole Jensen
Original assignee: Ole Jensen
Priority date: 1988-05-04
Filing date: 1989-05-03
Publication date: 1989-11-16
Also published as: DK163886C; DK243288D0; DK163886B; DK243288A; AU3563189A

Abstract

A device for applying plaster comprising a housing having an inlet opening (23), an outlet opening (24) as well as an intermediate conduit (25) for the unhardened plaster mixture fed into the inlet opening under pressure. The inlet opening (23), the outlet opening (24) and the intermediate conduit (25) are arranged in a plurality of sets, each set having an ejecting means (26) for ejecting the plaster through the outlet opening (24). Air nozzles (31, 32) are attached to the outlet openings (24), said air nozzles adjusting the thickness of the ejected jets of plaster. The plaster is a mixture of gypsum, filler in form of granulated rockwool, and water, as well as optionally a binder.

Description

Title: Plaster, a method of preparing said plaster and a device for the application thereof.

Technical Field

The present invention relates to a plaster comprising a mixture of gypsum, filler and water, a method of preparing said plaster, whereby first the gypsum and the filler are mixed and then water is added, whereupon the plaster is applied and left to harden, as well as a device for applying said plaster.

Background Art

Different plasters are known containing sand stopping, gypsum or similar materials. These types of plaster are often difficult to apply and frequently require secondary treatment before paint or wall coverings, such as wallpaper or the like, can be applied.

Disclosure of the Invention

The plaster according to the present invention is charac¬ terised in that granulated rockwool is used as filler. The resulting plaster can be applied in a single operation regardless of the thickness of the applied layer, forming an even and smooth surface, which upon setting does not develop cracks or collapse. After an ordinary period of hardening all types of painting or wall coverings, such as wallpaper or the like, can be applied to the surface without any kind of preceding treatment. This is par¬ ticularly due to the combination of gypsum and granulated rockwool, where the tendency of the gypsum to shrink during hardening is compensated by the ability of the rockwool to expand, so that the mixture retains its volume. The granulated rockwool is a material comprising entangled rockwool fibres forming small granules. After hardening the plaster possesses an even, smooth surface although the base may be uneven due to projections and holes.

According to the invention a method of preparing the plaster comprising admixing gypsum and a filler, and sub¬ sequently adding water, whereupon the plaster is applied and left to harden, is characterised by using granulated rockwool as filler.

In a preferred embodiment of the inventions gypsum can be added to the rockwool prior to the addition of water, the weight ratio of gypsum to rockwool being approx. 4:1.

Furthermore, according to the invention, a binder can be added, such as polyvinyl alcohol, thus obtaining a hardened plaster of especially high strength. In a particularly suitable embodiment of invention the granulated rockwool can be a particularly bulky or voluminous granulated rockwool, such as of the type SPIN ROCK, FIU.

The device for applying the plaster according to the invention and comprising a housing having an Inlet opening, an outlet opening as well as an intermediate conduit for the unhardened plaster fed Into the inlet opening under pressure is characterised in. that the housing comprises a plurality of sets of inlet openings, outlet openings and intermediate conduits, said sets being adjacent each other but mutually separated, each set having an ejecting means for ejecting the plaster through the respective outlet opening, and that air nozzles are provided adjacent the outlet openings, said air nozzles adjusting the thickness of the ejected jets of plaster.

This device is particularly suitable to be used for apply- ing the plaster according to the invention in a simple and inexpensive manner, as it is much less time-consuming compared to known methods . The device allows the applica- tion of the plaster in such a way that, if desired, the surface is immediately ready for the application of paint or wall coverings.

In a preferred embodiment of the device, the ejecting means can be coaxially attached bucket wheels driven by a common motor via a common shaft.

According to the invention the inlet openings can be fed via a common hopper extending in the direction of the plaster flow and being connected to a handle for manually carrying the device, the plaster being supplied to the hopper via said handle. As a result the device is par¬ ticularly simple and easy to handle manually.

An especially uniform distribution of the plaster is obtained, when, according to the invention, each set of inlet openings, outlet openings and conduits with corresponding bucket wheels is comparatively narrow seen in the axial direction of the bucket wheels, while at right angles to said direction and transverse to the flow direction of the plaster the dimension of the inlet open¬ ings is approximately of the same size as the diameter of the bucket wheel, and the corresponding dimension of the outlet openings is several times larger or approximately of the same size as the diameter of the bucket wheel .

Finally, according to the invention, an air nozzle can be provided on each side of each outlet opening seen in the direction of the largest dimension of the outlet opening, and the air nozzles on each side of the outlet openings are manually adjustable around a common axis of rotation by means provided at the side of the housing.

Brief Description of the Drawing The invention is described in greater detail below and with reference to the accompanying drawings , in which

Fig. 1 illustrates a portion of a device according to the invention with some parts not shown for the sake of clarity, the flow path of the plaster being indicated by dotted lines ,

Fig. 2 is a top view of Fig. 1,

Fig. 3 is a sectional view along the line I-I of Fig. 2 Illustrating the front portion of the device according to the invention, and

Fig. 4 is a front view on a slightly larger scale of an element corresponding to the one of Fig. 3, the front portion of the device being composed of such elements and an adjacent element indicated by dotted lines.

Best Mode for Carrying Out the Invention

The device of Figs. 1 and 2 comprises a tube-shaped handle 1 only partly shown for the sake of clarity in the Figures. The front of the handle 1 is connected to the head of the device provided with the general reference numeral 2. The head 2 comprises a hopper 3 adjacent the handle 1, the inside of said hopper having a funnel-shaped flow passage 4 the cross-sectional area of which increases symmetrically to both sides from the end closest to the handle 1, while said area decreases also substantially symmetrically in a direction at right angles thereto. At its front the hopper 3 is connected (not shown in detail) to a front ejecting means having the general reference numeral 5. The ejecting means 5 comprises a plurality of identical elements 6-20, one end of which is closed by an end cover 21. The elements 6-20 are preferably cast in form of an integral unit of a suitable plastic material. Each element has substantially the form of a plate. One side of the element is provided with a recess 22 of a substantially rectangular cross -section seen in the direction at right angles to the largest surface of said element, cf. Fig. 5 4.

When put together the recesses 22 of the elements 6-20 form an extension of the funnel-shaped flow passage 4 of the hopper 3, cf. Figs. 3 and 4 being a side and front

10 view, respectively, of one 12 of the elements. At the end adjacent the hopper 3 each recess 22 defines an inlet opening 23, and at the opposite end each recess 22 defines an outlet opening 24. A conduit 25 between the inlet and the outlet opening is provided to receive a rotating bucket

15 wheel 26. The inlet opening 23 has a cross -sectional area corresponding to the dimension of the flow passage 4 of the hopper 3, seen in the direction parallel to the largest surface of the element 12, the end surfaces of the inlet opening 23 seen in said direction flushing with adjacent

20 surfaces of the flow passage 4. The conduit 25 in each element 12 widens from the inlet opening 23 in a direction parallel to the largest surface of the element and sub¬ stantially at right angles to the direction from the inlet opening 23 to the outlet opening 24. Adjacent the inlet

25 opening 23 the conduit 25 forms a curved surface 27 at one side, i.e. the lower side in Fig. 3, said surface nearly abutting the periphery of the bucket wheel 26. The widening of the conduit 25 extends from a cross-section smaller than the radius of the bucket wheel 26 to a cross-

30 section corresponding to the diameter of the bucket wheel. The conduit 25 continues into the outlet opening 24 having the same dimension as the conduit at this point. Opposite the curved surface 27 an end surface 28 of the conduit 25 extends smoothly from the inlet opening 23 to the outlet

35 24 and almost tangentially to the periphery of the bucket wheel 26 so that said bucket wheel 26 is also nearly abutting the surface 28. The bucket wheel 26 is fastened to a shaft 29 extending through all the elements 6-20 and common to all bucket wheels 26 provided in the recesses 22 between the elements 6-20. The shaft 29 extends through the end cover 21 abutting the element 20 and is connected to a motor 57 only indicated in Figs. 1 and 2. The motor 57 ^'is provided to drive the shaft 29 and thus all bucket wheels 26 in such a direction that the individual buckets after having passed the curved surface 27 in each conduit 25 pass across the inlet opening 23 and further to the direct vicinity of the almost tangential end surface 28. The bucket wheels thus rotate in the direction indicated by the arrow 30 of Fig. 3.

The front of the ejecting means, i.e. the side opposite the hopper 3, is provided with a row of air nozzles on each side of the row of outlet openings 24, said air nozzles running parallel to the shaft 29 of the bucket wheels 26. Air nozzles 31, 32 are situated on each side of the recess 22, cf . Figs. 3 and 4, and comprise rotatable bodies, 33, 34, each having an oblong, radial through passage 35, 36. The rotatable bodies 33, 34 are received in corresponding recesses 38, 39 arranged on the same side of the element 12 as the recess 22 and ending at the front of the element 12 at the same side as the outlet opening 24. Each end of the rotatable bodies 33 and 34 is provided with an axial pin 39, 40, cf. Fig. 3. One of the axial pins is received In a coaxially arranged bore 41, 42 in the same element 12, while the opposite pin is received in a corresponding bore in the adjacent element 13, cf. Fig. 4. The rotatable bodies 33, 34 in each of the elements 6-20 are interconnected by their axial pins. The axial pins are provided with engaging means (not shown) allowing a simultaneous rotation of the interconnected bodies by activating a button 43, 44, cf. Figs. 1 and 2, at the end of the ejecting means 5. Each button is In engagement with the adjacent nozzle via the end cover 21. Further backward on the element 12, seen in the direc¬ tion of the inlet opening 23, an air conduit 45, 46 is provided. One end of the air conduit passes into the recesses 37, 38 of the rotatable bodies 33, 34, while the other end communicates with an air passage 47, 48 passing through all the elements, cf. Fig. 3. Each air passage communicates with a connecting sleeve 49, 50 for a pressurized air hose through the end cover 21, cf. Figs. 1 and 2.

The main portions of the device, such as the handle 1, the hopper 3 and the ejecting means 5 as well as their in¬ dividual parts are fastened to each other by suitable means not shown in detail. The joints are provided with suitable sealings so that the individual parts are sealingly connected.

When using the device according to the invention the end of the handle 1 opposite the head 2 is connected to a source of plaster, said plaster being pressure-fed through the handle 1 to the head 2 by means of a suitable pump. The plaster flows through the flow passage 4 and is dis¬ tributed to the inlet openings 23 as indicated by the arrows of Fig. 2. From there the plaster flows to the bucket wheels 26 rotated by means of the motor 57, said bucket wheels accelerating the plaster to a velocity where it is ejected through the outlet openings 24 onto the wall to be treated. The jets of plaster leaving the outlet openings 24 tend to spread to both sides in a direction at right angles to the common shaft 29 of the bucket wheels 26. The spreading can be avoided by means of the adjustable air nozzles 31, 32 to be adjusted to the desired strength and, to a lesser degree, in a desired direction by the buttons 43, 44. The thickness of the layer of plaster is also adjusted by the air nozzles 31, 32. The thinner the jet of plaster the thinner the layer of plaster on the wall ,

The device is described with reference to a preferred embodiment. Many alterations can, however, be made without thereby deviating from the scope of the invention. The bucket wheel 26 can, for instance, have another shape as the one shown, since it only accelerates the pressure- fed plaster to the ejecting velocity. The number of elements cooperating to define the flow passages may vary. The same applies to the dimensions of the elements. As suggested the elements are advantageously manufactured of suitable plastics, which should be such that the device is easily handled and operated by a user holding the handle in his or her hands .

The described device is advantageously used together with a plaster comprising gypsum, filler and water, the filler being granulated rockwool mixed with gypsum prior to the addition of water. The gypsum and the filler are mixed at a weight ratio of advantageously 4:1, whereupon the water is added in an amount dependent on the desired consistency, binder and colourings being optionally added.

The granulated rockwool may be of several types all avail- able from Rockwool International. The following products have been found particularly suitable in the present connection: SPIN ROCK FIU and the Rockfil types RF 5308, 5708 and 5908. The products are all in form of granules of entangled rockwool fibres or mineral wool fibres.

In a test mixture 1 kg gypsum was mixed with 250 g SPIN ROCK fibres, whereupon 10 g binder comprising polyvinyl alcohol was added to approx. 1 1 water. Then the gypsum/fibre mixture was mixed with the water/binder mixture. The resulting product displayed good results with respect to useage as plaster. The plaster is advantageously used together with the described device, but can also be manually applied. In the latter case it is applied by large spatulas with subsequent smoothing.

The plaster is described in a preferred composition, which can be varied in many ways without thereby deviating from the scope of the invention. The important feature is that the tendency of the gypsum to shrink is combined with the ability of the granulated rockwool to expand so that these two properties compensate each other.

Claims

Claims :

1. A plaster comprising a mixture of gypsum, filler and water, c h a r a c t e r i s e d in that granulated rockwool is used as filler.

2. A method of preparing a plaster according to claim 1, said method comprising admixing gypsum and a filler, and subsequently adding water, whereupon the plaster is applied and left to harden; c h a r a c t e r i s e d by using granulated rockwool as filler.

3. A method as claimed in claim 2, c h a r a c t e r ¬ i s e by adding gypsum to the rockwool prior to the addition of water, the weight ratio of gypsum to rockwool being approx. 4:1.

4. A method as claimed in claim 2 or 3, c h a r a c ¬ e r i s e d by further adding a binder, such as poly- vinyl alcohol.

5. A method as claimed In claim 2, 3 or 4, c h a r a c¬ t e r i s e d by the granulated rockwool being a particularly bulky or voluminous granulated rockwool, such as of the type SEIN ROCK, FITJ.

6. A device for applying the plaster according to claims 1-5, said device comprising a housing having an inlet opening, an outlet opening as well as an intermediate conduit for the unhardened plaster fed into the inlet opening under pressure, c h a r a c t e r i s e d in that the housing comprises a plurality of sets of inlet openings (23), outlet openings (24) and intermediate conduits (25), said sets being adjacent each other but mutually separated, each set having an ejecting means (26) for ejecting the plaster through the respective outlet opening (24), and that air nozzles (31, 32) are provided adjacent the outlet openings (24), said air nozzles ad¬ justing the thickness of the ejected jets of plaster.

7. A device as claimed in claim 6, c h a r a c t e r - i s e d in that the ejecting means (26) are coaxially attached bucket wheels driven by a common motor via a common shaft (29).

8. A device as claimed in claim 6 or 7, c h a r a c - t e r i s e d in that the inlet openings (23) are fed via a common hopper (3) extending in the direction of the plaster flow and being connected to a handle (1) for manually carrying the device, the plaster being supplied to the hopper (3) via said handle.

9. A device as claimed in claim 6, 7 or 8 , c h a r a c¬ t e r i s e d in that each set of inlet openings (23) , outlet openings (24) and conduits (25) with corresponding bucket wheels (26) is comparatively narrow seen in the axial direction of the bucket wheels , while at right angles to said direction and transverse to the flow direction of the plaster the dimension of the inlet openings is approximately of the same size as the diameter of the bucket wheel, and the corresponding dimension of the outlet openings is several times larger or approximately of the same size as the diameter of the bucket wheel.

10. A device as claimed in claim 9, c h a r a c t e r ¬ i s e d in that an air nozzle (31, 32) is provided on each side of each outlet opening (24) seen in the direction of the largest dimension of the outlet opening, and that the air nozzles on each side of the outlet openings are manually adjustable around a common axis of rotation by means (43, 44) provided at the side of the housing.