DE1275921B - Process for smoothing and pore filling of wooden surfaces - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

B44d

German class: 75 c -5/02

Number: 1275 921

File number: P 12 75 921.6-45 (H 42267)

Filing date: April 11, 1961

Opening day: August 22, 1968

The invention relates to an improved method for preparing wood and synthetic wood surfaces, which protective or beautification covers should receive. Under synthetic wood is here understood a product, which consists of wood flakes, wood chips and even sawdust and as a binding a synthetic glue, for example a urea-formaldehyde condensation product, contains.

The usual method to date to prepare a wood surface for a coating has been the First sand the surface smooth with sandpaper and then the pores with a suitable filler close. When applying the filler and possibly also a final coating many of the small chips and fibers, barely noticeable to the naked eye, which one with Sandpaper characterize the processed wood surface, enlarged and particularly noticeable, so that a further sandpaper treatment was inevitable.

Furthermore, after applying the first final coating on the with filler treated and re-sanded surface found that depending on the hardness of the wood the Grain is more or less coarsened, so that additional grinding with sandpaper is necessary will.

In the Austrian patent specification 141829 is a Method described the surface of wood by abrasive while rubbing off wood dust in connection with the dissolved lacquer base to be rubbed into the pores during the operation Process pore filler. This procedure could not be put into practice, because it uses a special abrasive that is dissolved by a solvent and worked into the pores is required.

The previous sandpaper treatment of the wood surface is of course mandatory Prerequisite for achieving a satisfactory, smooth coating. Closing the surface pores is also an inevitable requirement, especially when it comes to wood or Synthetic wood with a coarse structure is involved. Therefore, if you combine these two operations and at the same time and thereby avoid a subsequent sandpaper treatment, there would be enormous cost savings in the finishing of wood and synthetic wood surfaces result.

The present invention solves this problem.

Previous Attempts at the Process of Wood Preparation Process for Screeding and Pore Filling
Wooden surfaces

Applicant:

Gilbert F. Hoffmann,

Mukwanago, Wis. (V. St. A.)

Representative:

Dipl.-Ing. H. W. Schöning, patent attorney,

2000 Hamburg 1, Mönckebergstr. 31

Named as inventor:
Gilbert F. Hoffmann,
Mukwanago, Wis. (V. St. A.)

Claimed priority:

V. St. v. America from 1 Wed 1960 (40 332)

To improve surfaces, for example the so-called »microseak process according to the USA patent specification 2 827 935, after which the surface sanded with sandpaper is treated with heat and pressure tried to do without the usual fillers. To some extent there was one here Success, but even these older methods still require two completely separate operations, namely the sanding with sandpaper and the pressure-heat treatment. In addition, is also the pressure-heat treatment to close the pores, if it is synthetic wood or if the structure of the wood is to be preserved or emphasized, in no way satisfactory.

Notwithstanding this, the invention enables it in an economical manner in a single simple one Working step to treat a wood or synthetic wood surface with sandpaper to fill its pores and to give it the desired smoothness and density.

The invention relates to a method for smoothing and pore filling of wooden surfaces by grinding in the presence of synthetic resins and solvents, which is characterized in that a high molecular weight synthetic resin is supplied in the form of a dispersion.

The high molecular weight synthetic resin does not melt or fuse. It softens those of the surface

809 597/383

particles removed by the sandpaper treatment and becomes associated with these particles in the pores pushed into the treated surface or compacted there. Since the resin does not melt, the sanding surface of the sandpaper cannot stick or become shiny, but remains in the The opposite is completely functional. Of course, the synthetic resin can be used if you have the sanding surface lets dry without prior cleaning,

out, after which a suitable high molecular weight synthetic resin can be produced.

example 1

for a suitable high molecular weight synthetic resin 90.81 water with 1.81 kg dioctyl sodium sulfosuccinate and 0.951% Dow Antifoam-A (anti-foaming agent Silicone resin) in a mixture of toluene and butyl acetate (known commercially as E-3626)

stick firmly. The temperature ^{is raised to 82 °} C. by washing out with the io. For this heated, liquid carrier, however, the active liquid solution can quickly be restored to an alkyd resin solution. (short oil, non-drying alkyd resin) with 60%

This "wet" sandpaper treatment closes and solids (product of the company Archer Daniels, not only effectively seals the surface pores, son-Midland, Aroplaz 2570) and 54.9 1 unmodified this creates a surface that is essentially 15 urea-formaldehyde resin solution (product of the is smoother and denser than the surface, which American Cyanamide Beetle 216-8) usually has with a dry sandpaper treated, premixed and heated to 69 ° C. The success is achievable. During the sandpaper treatment mixture is then through high-speed airing a large part of the emulsification used evaporates. The resulting emulsion is at Solvent, so that the working temperature between 71 and 77 ° C is already 1 hour surface is slightly dried and also moved in the »air-long. Another precondensation takes place dry «state can be left behind. For then catalytically by adding 680 g of 70% However, the manufacturing process is best when that is done with nitric acid in 3750 g of water. One leaves the approach Sandpaper treated and smoothed workpiece rest for another hour between 66 and 71 ° C, under a series of heat lamps or a 25 After adding the acid, the emulsion breaks down usual dryer runs through it. and gradually and forms a flocculation. The

If a particularly fine surface is required, separated water is drained and the precondensation is The sandpaper treatment can be thoroughly washed in two stages, first with be carried out with the second stage un- water and then with alcohol to as much as possible the first is followed by and under noticeably lent the water contained in the flocculation lower pressure is carried out. remove.

The abrasive grain size of the sandpaper is not The end product is a relatively anhydrous,

critical; for example, grits 80 to 400, highly precondensed and insoluble, granules were used. However, the best results were found in the high molecular weight synthetic resin, which is easily converted into Grain size range 220 to 320, corresponding to the 35 different solvents, for example in the Sandpaper numbers 6/0 to 9/0. previously mentioned, such as water, butyl alcohol, isopro-

Although the selection of a suitable high molecular weight synthetic resin poses no difficulties for those skilled in the art prepared, it should be mentioned that extremely suitable high molecular weight synthetic resins are obtained 4 ° the convertible precondensate resin-forming which is produced by reacting a convertible, precondensate resin suspended in an aqueous emulsion organic substance such as an alkyd resin and urea-formaldehyde condensates

or vinyl toluene by mixing the suspension straight away (Aroplaz 2570). This approach is timely moved and heated, then the reacted together with 48.5 kg of carnauba wax to 88 ° C Synthetic resin in the form of a heat-up until the wax has completely melted and flakes or a coagulate separate and that is dissolved. The mixture is in 2421 water with Remove water. After removing the water 7.26 kg of dioctyl sodium sulfosuccinate and 1.891 silicon and suitable drying, the high molecular weight 50 konharz antifoam agent E-3626 is emulsified Synthetic resin in granulated, non-sticky form before heating to 82 ° C with vigorous agitation. the and can then be in various liquid carrier emulsion for about 30 minutes near the boiling point, including water, butyl alcohol, isopro- point and then with 454 g of 70% saline alcohol, Paint solvents and actually catalyzed in pitric acid in 3170 g of water. After this almost all organic solvents, again the substances are left to rest for another half hour be dispersed. let, the flocculation is deposited, which then

Determined thoroughly with water and then Isopro in the practice of the invention the concentration in which the pyl alcohol is washed out. Here, too, is that again Solvent dispersed high molecular weight products chose a relatively dry, high molecular weight ren synthetic resin only by the desired hand- 60 and insoluble, granular or crumbly substance that lungsart. 1 kg of dry, high molecular weight synthetic resin easily dissolves in any of the liquid, previously

Pyl alcohol, paint solvent and the like, redispersible is.

Example 2 for a suitable high molecular weight synthetic resin

94.6 1 unmodified urea-formaldehyde resin solution with 60%> Solids (Beetle 216-8) is mixed with 1701 alkyd resin solution with 60% solids

dispersed in 4.171 of the solvent can be Process well if the dispersion is brushed or rolled on. When spraying the Concentration can be kept lower.

Although the manufacturing process (s) of the high molecular weight synthetic resins do not form part of this invention form, two special processes mentioned carrier substances are allowed to redisperse. Example 3

65 Here the coating applied to the panels consists of a precondensate-alkyd-urea-formaldehyde-synthetic resin mixture according to example 1 or 2, which is a polyester resin and burnt umber

is added. The synthetic resin made up 20% of the whole. Used as a dispersant VMP naphtha used.

Example 4

The devices used to carry out this example are essentially the same as in the previous examples. The machined areas are z. B. Walnut; Mahogany and Birch plywood panels, also chipboard. An alkyd-urea-formaldehyde resin precondensate is applied to the surfaces to be processed according to example 1 or 2, which is dispersed in isopropyl alcohol, rolled on. Unnecessary material is removed a doctor blade removed. The surfaces moistened in this way are processed in a grinding machine. For the walnut, mahogany and birch panels, a tape with a grain size of 0.035 mm used. The grain size used for the chipboard is 0.18 mm.

The invention is based on the finding that by sanding surfaces of a synthetic wood or any coarse-grained, natural wood in the presence of synthetic resins and solvents, a high molecular weight synthetic resin is supplied in the form of a dispersion, while the surface is still damp a completely unexpected result is achieved. Despite the high porosity of synthetic wood, for example all pores are effectively closed and at the same time the surface of the wood becomes made so completely smooth that subsequent sandpaper treatment is unnecessary. The surface also becomes so dense that it is immediately ready to receive any of the usual final covers.

It is not known exactly what happened during the described "wet" sandpaper treatment goes; but the insoluble and infusible, but smoothing high-molecular synthetic resin becomes apparent thoroughly mixed with the particles removed from the surface by the sandpaper treatment, which are then compressed into the pores of the surface. Regardless of the underlying scientific explanation it is known, however, that with this simple process even the surface of highly porous synthetic wood becomes completely ready to receive any of the known ones Coating compounds.

Synthetic woods that have been successfully treated according to this invention are, for example, timblend, a product of the Roddis Division of Weyerhaeuser Company and Novaply, a product of U.S. Plywood Company.

If desired, the high molecular weight synthetic resin can also have a coloring component in the form of a suitable dye or pigment can be added.

The high molecular weight synthetic resins produced according to Examples 1 and 2 are insoluble and infusible. For the practice of this invention, however, it is not absolutely necessary that these be high molecular weight Synthetic resins are absolutely insoluble and infusible. It is sufficient if the synthetic resins are in are insoluble in the liquid dispersant used and do not yet melt at the temperatures that arise in the process.

In addition to the high molecular weight synthetic resins according to the two manufacturing processes described above it is also possible to use plastisols and organols as a dispersion. For example, there is polyvinyl chloride plastisol with the plasticizer dioctyl phthalate or dioctyl sebacate or tricresyl phthalate, satisfactory results. The same plastisols diluted with a volatile organic liquid are examples of useful organosols.

The use of plastisols or organosols has the advantage that you get a more durable surface can be achieved by simply heating the treated surface to a temperature which is high enough to bring the dispersed resin into solid solution.

Although the inventive method is completely can be carried out manually, it is understandably preferable in production, Machines to use. The drawing in FIG. 1 is a schematic, perspective view

a grinding machine suitable for the method according to the invention and

F i g. Figure 2 is a side view of the same, somewhat modified machine on a reduced scale.

In both cases it is a more or less common belt grinder that one also referred to as a high-speed sanding machine and consists of a sanding or emery belt 5, which preferably runs over a driven cylinder 6 and a guide roller 7. Both the cylinder 6 and the roller 7 run in suitable bearings (not shown). The cylinder 6 is in any Way, for example driven by a (not shown) electric motor at high speed. The surface of the cylinder 6 is covered with a layer 8 of rubber or the like Part of the sanding belt on which the cylinder strikes the workpiece, a flexible surface to build. Because the sanding belt runs in the same direction as the workpiece is through the machine moves, special means must be provided to control the feed of the workpiece and to hold the workpiece accordingly. This is done with rubber rollers 9 with friction on the underside attack the workpiece and driven at low speed in the feed direction of the workpiece will. The feed rate of the workpiece should be in the order of magnitude of 10 to 60 m / min if the speed of the sanding belt is around 760 m / min.

Understandably, the distance between the cylinder 6 and the feed rollers 9 must be adjustable in order to be able to take sheets or workpieces of different thicknesses into account.

As shown, the guide roller 7 is arranged "behind" the cylinder 6 in such a way that even without special Hold-down no part of the lower run of the sanding belt touches the workpiece. if it however, if desired, a pressure shoe 11 can be provided around the lower run of the sanding belt to press slightly against the workpiece surface and in this way a secondary sandpaper treatment to be carried out with less pressure. Secondary grinding takes care of this working method for a very fine workpiece surface.

The high molecular weight synthetic resin dispersed in the solvent can be applied to the upper side of the workpiece surface can be applied before it touches the sanding belt, for example by using a roller

12 provides with which the liquid synthetic resin dispersion is transferred from a trough 13.

The way in which the high molecular weight synthetic resin is applied to the workpiece as a dispersion is understandably can be modified in various ways. So can in place of an application application with brushes can also be provided with rollers, or it can also be as in Fig. 2, a row of nozzles 14 distributed across the width of the machine for spraying be used. These nozzles, only one of which is shown, can be arranged in such a way that that they spray directly in front of the grinding point on the workpiece surface or they can also, as in FIG. 2, be arranged so that they spray their jets onto the surface of the Align the sanding belt when it runs around the cylinder 6. In this case, a Squeegee 15 is provided to distribute the dispersion evenly over the surface of the sanding belt. The doctor blade must understandably consist of a material which by firm contact with the The surface of the sanding belt is not affected too much. For example, more natural is suitable or synthetic rubber of medium hardness.

The spraying of the dispersion onto the surface of the abrasive belt according to FIG. 2 has the advantage that the surface is kept cleaner and no clumping or sticking is easy of the operation can occur.

Another way to practice the invention is to insert the abrasive particles into the bring in liquid dispersion fed in. You can then use a regular Abrasive belt can be dispensed with, since then a belt or some other fast moving smooth contact surface is used. Obviously occurs in such a modified embodiment of the Invention does not solve the problem of keeping the belt or its equivalent pure and functional on.

The arrangement for this modified method according to the invention can be designed in exactly the same way as according to FIG. 1 or 2 with the exception that the belt S is formed with a smooth surface and can be made of any suitable material. From the above description follows in conjunction with the drawings to those skilled in the art that this invention in processing of wood or synthetic wood surfaces for the application of a final coating to a significant cost savings. Although the invention is particularly useful for natural Wood or synthetic wood, other materials, for example fiber boards or so-called Hardboard, can be treated in a favorable manner according to this method. Such modifications The invention described above are intended to be within the scope of the following claims lie.

Claims (4)

Patent claims: 1. Process for smoothing and pore filling of wooden surfaces by sanding in the presence of synthetic resins and solvents, characterized in that a high molecular weight Synthetic resin is supplied in the form of a dispersion. 2. The method according to claim 1, characterized in that the grinding process with a Belt sander running and the dispersion on the wood surface immediately before whose contact with the sanding belt is applied. 3. The method according to claim 1 or 2, characterized in that a plastisol is used as the dispersion or Organosol is used. 4. The method according to claim 2 or 3, characterized in that instead of the grinding belt a fast moving, smooth pressure surface is used and loose abrasive particles in the supplied dispersion can be introduced. Considered publications:
Austrian patent specification No. 141 829. When the application was announced, six models were laid out. 1 sheet of drawings 809 597/383 8. 68 © Bundesdruckerei Berlin