US3535839A - Pretreated sealed parquet plate - Google Patents

Description

Gct. 27, 1.970 J. STRBING v3,=,35,839

PRETREATED SEALED PARQUET PLATE Filed May 29, 1968 s sheets-sheet 1 V-m Fig1 F192 Oct. 27, 1970 J. s-rRUBlNG 3,535,839

y PRETREATED SEALED PARQUET PLATE Filed May 29, 1968 3 Sheets-Sheet 2 INVENTOR, Jaarw/M freue/m6 Oct. 27, 1970 J. sTRUBlNG 3,535,839

PRETREATED SEALED PARQUET PLATE Filed May 29,1968 3 Sheets-Sheet 3 Y Fig. 11 Fig. 12

United States Patent U.S. Cl. 52-99 1 Claim ABSTRACT 0F THE DISCLOSURE A parquet flooring plate or unit is composed of elementary elongate Wooden strips arranged in square-shaped groups, and a plurality of such groups are joined to form a rectangular parquet unit in which the individual strips and the different square-shaped groups are held together prior to laying the floor by elastically extensible tapes glued to the underside of the assembled unit. The units have their top face ground and sealed in the factory prior to laying the oor. After sealing, the continuous sealing agent layer on the top face of the unit is broken across all joints between adjacent elementary strips in the unit by bending the strips relatively to each other to subject the sealing agent layer above said joints to tensile stress, while said extensible tapes on the underside are yielding and remain intact.

The invention relates to sealed parquet plates, ready to be laid on a floor and composed of individual small wooden blocks or strips joined together to form a parquet panel.

lParquet plates which are composed of such strips, particularly so-called mosaic parquet panels in which the strips are joined checkerboardlike with crossed direction of grain are provided on the underside with a bond consisting of narrow paper or fabric strips in order to maintain the individual wooden Iblocks or strips in assembled condition. These bonding strips are applied flat to the underside of the panels or are sunk for about one half millimetre into the bottom face of the panel, whereby the thickness olf the wooden blocks or strips is substantially conserved as useful thickness. The plates or panels are laid on a subiioor by the aid of normal aqueous dispersion adhesives, usually PVA adhesive. For sealing the parquet flooring, normal varnish is used.

It is no difficult problem, to lay mosaic parquet plates with hydrous adhesive. The individual blocks or strips slightly swell at the underside when the panels are laid into the adhesive layer. The deformations, however, are small and are removed when the flooring subsequently is ground, if they did not disappear already by compensation of the moisture content. Also subsequent sealing of the laid flooring does not offer any difficulties. The stresses exerted by the drying and setting sealing layer are insignicant as compared with the stresses which can be absorbed by the adhesive.

Difficulties, however, will be experienced when the parquet panels are ground and sealed in the parquet manufacturing plant, thus prior to being laid to a floor. When already sealed parquet panels are laid, these panels are no longer loose articulated units of individual parquet blocks or strips, but stiff and rigid wooden plates have to be laid, since obviously all individual wooden blocks or strips of the sealed plates are rigidly connected to each other by the sealing varnish transversely to the direction of grain. This rigid bonding of the individual wooden strips is not desired, however, it cannot be avoided, since the sealing layer forms a iilm which bridges the joints between the i ce strips and also penetrates into the joints and causes the adjacent blocks or strips to become glued to each other.

When such a rigid parquet panel of a width which is many times larger than the width of an individual block or strip, is moistened on its underside upon being laid into the layer of adhesive, the swelling and deformation have a very much increased effect, since as is well known, the height of arc or deflection of a segment of a circle increases with the square of its length. Flooring surfaces having such concave, deformed parquet plates have not only a poor appearance but are technically inadequate, since the deformed plates are only bonded here and there at certain points to the subfloor.

Different means have already been used to eliminate these undesired effects, which until now prevented an efficient use of parquet panels sealed in the factory prior to laying on the floor. It is possible to use dehydrated adhesives for laying a lioor. Such adhesives, however, have technical disadvantages; they often are harmful to health and inammable and have the tendency of aging and becoming brittle.

Another possibility of avoiding the deformation of parquet panels sealed prior to laying is the covering of the underside of the panels, i.e., to protect the panels against the water in the adhesive. For example, bituminated paper can be glued to the underside of the panels. Such an intermediate layer, however, can impair the bonding of the parquet panels with the subfloor and render the lloor inapt for use. Continuous carrier layers or protecting layers having improved stability properties have also been used, but such additional layers are expensive and result in other drawbacks.

It is also possible to modify the composition of the sealing agents in order to avoid the sticking together of the joints between the elementary parquet strips or blocks, which is principally responsible for all difficulties encountered. When a sealing varnish is used having a very low content of solid bodies, and moreover the varnish is applied in a quite thin layer, the parquet strips or blocks treated with such a varnish stick only slightly together when the correct application procedure is used, so that the feared deformation of the panels does not occur. The sealing quality obtained by such agents, however, is deficient and poorly sealed parquet plates are unfit for use.

Also, the individual elementary parquet blocks or strips could be sealed rst and then assembled to form panels. This procedure, however, is not suitable, since practically it is not possible to align the parquet blocks or strips without formation of disturbing lippings between adjacent strips, apart from a higher consumption of sealing agent.

It is an object of the present invention to provide a parquet plate which avoids the above mentioned drawbacks.

According to the invention bonding means of extensible and iiexible material are applied to the underside of the joined elementary parquet blocks or strips to hold them together prior to laying of the plates, the extensibility of said bonding means being at least twice as high as the extensibility of the sealing agent layer on the top side of the joined elementary blocks or strips, and the sealing agent layer being broken across all joints between adjacent elementary blocks or strips of the plate.

In mosaic parquet plates, in which the individual parquet blocks or strips are joined to form square elements and these latter are in turn joined checkerboardlike with crossed direction of grain to form a plate, the bonding means for the blocks or strips applied to the underside of the parquet plate conveniently consist of extensible tapes which extend across the joints -between the blocks or strips and along the marginal portions of said square elements.

The bonding means on the undersides of the plates can be formed also by adhesive coated threads or strings placed into grooves provided on the underside at the front ends of the blocks or strips and along the joints of adjacent square elements.

Preferably, the bonding means at the underside of the plates are glued by application of heat.

The invention also relates to a method for producing such sealed parquet plates ready for laying. This method comprises joining a number of elongated parquet blocks or strips, applying bonding means of extensible and flexible material to one side of said blocks or strips across the joints thereof for holding the blocks or strips in assembled relation, grinding and sealing the other side of the assembled blocks and strips, so as to form on said other side a layer of sealing agent continuously extending over the entire surface area of the assembled blocks or strips, and then breaking said sealing agent layer at the joints between said elementary blocks or strips by bending the blocks or strips relative to each other.

The invention will now be described with reference t the accompanying drawings in which,

FIG. l is a plan view on the underside of a parquet plate according to the invention,

FIG. la is an end view of the parquet plate of FIG. 1, viewed in the direction of arrows 1a in FIG. l;

FIGS. 2 to 10 serve to explain the method of production of a parquet plate ready for laying,

FIGS. l1 and 12 are top plan views of parquet plates according to the invention having a modified arrangement of the elementary blocks or strips.

FIG. 1 is a view of the underside of a parquet plate 1 assembled from a plurality of similar elementary wooden strips 2. A number of five strips 2, in the represented example, form rectangular or square groups, which are assembled checkerboardlike with crossed grain to form a plate. In order to hold the strips 2 in assembled relation prior to laying the plates to a floor, tapes 3 of an extensible and flexible material such as paper or plastic, coated or reinforced paper, are glued to the strips 2 at the underside of the plate, preferably by means of an elastic or extensible adhesive or by means of an adhesive which has been treated, for example heated to be temporarily elastic. Such a tape 3 extends along each of the four marginal portions of the plate transversely across the strips 2 of one group and along the outer strip 2 of the adjacent group of strips, and two further strips 2 extend along the two median lines of the plate to connect the ends of the strips 2 of one group with the longitudinal edge of the first strip of the adjacent group. The surface of the parquet plate may be grooved, as shown in FIG. la, to receive the tapes 3 at the locations described just above. This narrow connecting tape 3 suffices to hold the strips 2 together prior to laying the plates on a floor. The comparatively large Wood surface of a plate permits an effective bonding of the plate with the subfloor, so that the strength of interconnection of the individual strips by means of the tapes 3 is of secondary importance and uneveness between adjacent plates or formation of so-called lippings is not to be feared.

A plate composed in this manner of strips 2 in the factory is then ground and sealed also in the factory by the use of normal or conventional sealing varnish.

The parquet plate represented in FIG. 1 also can be produced in another manner. As represented in FIG. 2, a. plurality of parallel strips 2a can be joined to form a long band 4 and the individualwooden strips 2a are maintained together by tapes 3a which are glued to the underside of the assembled strips 3a. These tapes consist of the same material as the tapes 3 in FIG. l, i.e., of paper, plastic, or reinforced paper. Such a band 4 is then cut into portions of desired length which are ground and sealed in conventional manner by the use of normal sea1- ing varnish.

The sealing of the parquet bands formed by a certain number of strips 2a results in the undesired effect that the sealing agent penetrates into the joints between the adjacent individual strips 2a and causes them to stick together. This bonding together of the strips at the joints subsequently must be broken up, prior to assembling the sealed lengths of parquet bands to a parquet plate and before the plate can be laid to form a parquet flooring. This can be effected in simple manner by passing the band about a convex surface or guide roller 5 as shown in FIG. 3. The sealing agent layer 6 of the -band 4 shall be situated in the tension zone, thus on the outer or convex side of the band. When passing the band 4 over the surface 5, the strips 2a of the band are bent, the layer of sealing agent 6 at the joints and the varnish Which had penetrated at the joints along the longitudinal sides of the strips 2a is subjected to tensile stress and is broken, while the tapes 3a which hold the strips 2a together is not stressed and the band formation of the strips remains intact. From the band of strips 2a in which the strips still are interconnected by the tapes 3a but no longer stick together at the sealed face of the band, square groups of strips 2a are severed and assembled to form plates according to FIG. 1. For maintaining these groups of strips together, additional tapes 3 are glued across the joints between the groups. It is also possible to provide laterally projecting connecting tapes when producing the bands 4, which tapes would serve for later connecting the severed groups of strips 2a to form a plate.

When the parquet plate has been assembled as described with reference to FIG. 1, i.e., when for example four or sixteen squares formed of strips 2 are assembled to form a plate and are held together by means of tapes 3 on the underside, and only afterwards the plate as a whole is ground and sealed, it will be obvious that a device according to FIG. 3 can no longer be used for breaking up of the individual strips stuck together by the sealing agent, since each square group of strips is connected along at least one end side of the strips with a transversely directed strip of the adjacent square group. In order to subject the sealing agent layer to tensile strength and break it up by a slight total deformation, it is possible to proceed step by step as is shown diagrammatically in FIG. 4. Since the sealing agent layer is brittle, but the connection on the underside of the plates is elastically extensible as already mentioned, such deformations are effective in the desired manner, i.e., the sealing agent layer breaks up, while the connection of the underside remains intact. When, as shown in FIG. 4, breaking up is effected in two successive steps, the underside moreover is less stressed than the upper side provided with the sealing agent layer 6, since the angles o between adjacent inclined strips 2 on the underside measure only one-half of the angles p at the upper side of two inclined strips 2. When the tape connections at the underside of the plate are sufficiently extensible, it is possible to effect breaking-up in two steps as shown in FIG. 5.

FIGS. 6, 7 and 8 diagrammatically represent a device for breaking up of a parquet plate according to the method corresponding to the representation of FIG. 5, thus in two steps. Obviously, the device would differ in details but not in principle, when breaking up would be effected in three steps according to FIG. 4.

FIG. 6 illustrates a portion of a parquet plate. The five parquet strips 2 visible with their ends and forming a square group of strips, in FIG. 1, are designated by a, b, c, d and e. 3 designates the tape connection in the underside of the strips, 6 is the sealing agent layer, 7 represents a base plate, 8 are fixed ledges of a thickness of about 0.5 millimetres and slightly shorter than the parquet strips, i.e., they do not project beyond the edges of the square formed by the parquet strips. A rubber block 9 is disposed above the square group of strips a, b, c, d and e and can be pressed from above against the strips by means of a power press.

The ledges 8 are situated beneath the joints between the strips a and b, c and d and beneath the outer edge of the strip e when the parquet plate is placed into operating position in the device. For breaking up the sealing, the resilient rubber block 9 is lowered and pressed against the strips. Thereby the square of strips is deformed according to FIG. 7, i.e., it collapses in the spaces between the ledges 8 which act as support underneath alternate joints. In the joints supported by the ledges tensile stress is produced and the sealing agent layer is broken.

In order to breakup the remaining joints which had not been separated because they were not subjected to tensile stress, namely the joints between the strips b and c, d and e,the rubber plate 9 is lifted off and the parquet plate removed and brought into the device according to FIG. 8 and there again the parquet plate is compressed by a rubber block 9. The ledges 8 in this device are displaced for the width of one strip with respect to the arrangement of FIG. 7.

The described base plate 7 with ledges 8 suices to breakup one square group of strips 2 of a plate 1 according to FIG. 1. As already mentioned, the parquet plates to be treated consist of several square groups of strips 2, for example of four or sixteen squares. The complete apparatus for breaking up such a plate is designed correspondingly, and comprises also four or sixteen base plates 7 having ledges 8 and one or more rubber blocks 9.

A characteristic feature of the method is the limited bending of the strips as diagrammatically represented in FIGS. 4 and 5. The device according to FIGS. 6, 7 and 8 is only one of many possible forms of apparatus for effecting the breaking of the sealing agent layer. Instead of using a rubber block 9, for example a rigid pressing plate could be used which would be provided with ledges such as the ledges 8 of the lower base plate, but which would be displaced for the width of one strip 2 with respect to the ledges 8, in order to obtain an alternate bending of the strips.

It is also possible to provide the upper plate 10 with ledges 11, as represented in FIG. 9. FIG. l illustrates the manner of operation of this breaking-up device.

It is possible, instead of the xed supporting ledges 8, to use vertically movable ledges which can be sunk into the base plate, and which would be arranged opposite the joints between the strips a and b, b and c, c and d, d and e, and at the end of the strip e and to alternately cause those ledges to project out of the base plate, which will be used for effecting the deformation and breaking up of the group of strips. In this manner the transfer of the parquet plate from one device to a second device for breaking up all joints could be avoided. The counter pressure plate can consist of rubber or can also be formed by a rigid plate with controllable ledges-which can be sunk into the plate.

The method described with reference to FIGS. 6 to 10 for producing sealed mosaic pattern parquet plates which are ready for being laid is more advantageous than the method explained with reference to FIGS. 2 and 3, according to which the individual parquet strips arranged to form a continuous band are ground and sealed, and then the sealing layer is broken and only afterwards the strips are assembled to a nished parquet plate. By means of the first mentioned method according to which the strips are rst assembled to a mosaiclike arrangement and the assembled plate is ground and sealed and the strips are subsequently broken up, it is possible to produce parquet oorings in which any unevenness at the joints between the individual elementary strips and between the squares formed by groups of strips is avoided.

It is advantageous, for effecting breaking up of the sealing agent layer, as described with reference to FIGS. 6 to 10, to heat the underside of the parquet plate, so that when a thermoplastic adhesive or thermoplastic bonding material is used, the bonding tapes slightly soften 6 and the required extension of the tapes upon relative bending of the adjacent strips is facilitated.

Instead of using conecting tapes 3 for holding the strips 2 and the square groups of strips together, the connection of the assembled strips and groups of strips could also be made in such manner that a groove is cut into the wood at the underside of the plate along the ends of the strips at the edges of the plate and along the joints between the adjacent square portions, and an extensible string coated with adhesive is placed into the grooves. By means of such strings, the strips and the square groups of strips are maintained in assembled relation in the same manner as by means of the extensible tapes.

Obviously it is likewise possible to breakup the sealing layer when, instead of the tapes 3` a bonding means covering the entire area of the underside of the plate is used, for example a thin sheet of flexible, extensible material extending over the entire surface of the underside of the plate.

Besides the simple arrangement of strips according to FIG. l, also other arrangements of elementary blocks or strips are possible, for example as shown in FIGS. 1l and l2. For the stability of the plates, particular advantages can result by providing parquet strips or ledges 12 or 13 forming a frame along the outside of the square or reactangular assembly of elementary strips.

What is claimed is:

1. A sealed parquet plate ready for laying, composed of individual, elementary elongated parquet strips arranged in edge-to-edge, generally paralled relation, a continuous sealing agent layer applied on the top wear side of the strips, said layer penetrating said plate and together adjacent elongated strips whereby rigid bonding of said individual strips results due to the formation of the layer which bridges the joints between adjacent strips, and bonding means of extensible and flexible material applied to the underside of the elementary parquet strips, said agent layer and said bonding means holding said strips together in generally planar relation prior to the laying of the plates, the extensibility of said bonding means being at least twice as great as the extensibility of said sealing agent layer on the top side of said elementary strips, whereby breaking of said layer at the joints and the reestablishment of the independence of each of said elementary strips at the-wear surface while maintaining the integrity of the bonding means is facilitated to permit the use of hydrous adhesives in securing said parque plate to a iloor, subfloor and the like.

References Cited UNITED STATES PATENTS 1,43 3,077 10/1922 Hansen 161-113 1,778,250 10/ 1930 Elmendorf 144--281 1,819,775 8/1931 Elmendorf 137-505.24 2,118,841 5/ 1938 Elmendorf 52--313 2,835,936 5/ 1958 Elmendorf 161-38 3,282,010 11/1966 King 52-313 3,279,138 10/ 1966 Dittmar 52-390 FOREIGN PATENTS 1,069,350 1954 France.

291,256 1928 Great Britain.

704,707 1954 Great Britain.

965,595 1964 Great Britain. 1,021,062 1966 Great Britain.

HENRY C. SUTHERLAND, Primary Examiner U.S. Cl. X.R.

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