EP2662192B1

EP2662192B1 - Floor panel and method of its production

Info

Publication number: EP2662192B1
Application number: EP12167099.6A
Authority: EP
Inventors: Peter Gustafsson; Dan Sigfridsson
Original assignee: GUSTAF KAHR AB
Current assignee: GUSTAF KAHR AB
Priority date: 2012-05-08
Filing date: 2012-05-08
Publication date: 2017-07-12
Anticipated expiration: 2032-05-08
Also published as: EP2662192A1

Description

Technical field

The present disclosure relates to building panels and in particular to floor panels.

Background

It is known to provide parquet floor panels comprising a core which is formed of a plurality of low-grade wood blocks (also termed "slats" or "lamellae", which are arranged with their fiber direction perpendicular to a longitudinal direction of the floor panel. The core is sandwiched between a decorative layer, typically of an about 3 mm wood surface layer, and a balancing layer, typically of an about 2 mm wood veneer. The decorative layer and the balancing layer are glued to the core.
Floor panels as described above have been manufactured since the 1940's, and, apart from improvements in surface treatment, glue technology and the introduction of mechanical locking systems, have undergone relatively little change.
Examples of such parquet floor panels are disclosed in e.g. WO96/30177 A1 and US2005/0208255A1 . Further examples are provided in US2007/0292656A1 and US2004/0226243A1 .
It is desirable to further reduce the cost of floor panels of the above referenced type.

Summary

The present invention aims generally at overcoming or alleviating some disadvantages of prior art floor panels, with a particular focus on reduction of cost.
The invention is defined by the appended independent claims, with embodiments being set forth in the dependent claims, in the following description and in the drawings.
According to a first aspect, there is provided a floor panel, comprising a decorative layer and a core layer. The core is arranged below the decorative layer when the floor panel is substantially horizontally oriented. The core layer comprises a plurality of wood blocks arranged with their respective principal fiber directions substantially parallel with a plane defined by a major surface of the floor panel and substantially perpendicular to a principal direction of the floor panel. The core layer comprises a plurality of second material blocks, which are made from a different material than said wood blocks, and along the principal direction of the floor panel, the core layer presents alternating portions formed of said wood blocks and of said second material blocks.
A "principal fiber direction" is defined as the direction along which most of the fibers of the wood block extend. Typically, the principal fiber direction substantially coincides with a longitudinal direction of the wood block since lumber is normally sawn so as to have its fibers extend substantially longitudinally.
The "major surface" is typically the upwardly or downwardly surface of a floor panel. These surfaces are typically parallel with each other.
A "principal direction" of the floor panel may be a longitudinal direction in a case where the floor panel is elongate (i.e. substantially rectangular and non-square). As an alternative, or complement, the principal direction may be a direction which is substantially parallel with a direction along which another layer, e.g. the decorative layer and/or the balancing layer, forming part of the floor panel, presents its major bending strength and/or major tensile strength, such as a principal fiber direction of the decorative layer and/or of the balancing layer.
A "second material block" is understood as a block of material which is different from the material of the wood blocks. The second material blocks may e.g. be of generally lower quality (strength and/or stiffness) and/or cost than the wood blocks. Hence, the second material blocks mainly serve to fill the space between the wood blocks, and possibly to provide sound reduction.
A floor panel comprising a plurality of second material blocks may be produced at reduced cost compared with a floor panel comprising only wood blocks, since such second material may be less costly than even the lowest quality wood.
Moreover, the second material may reduce weight of the floor panel as compared to a floor panel comprising only wood, thus reducing cost of transportation and facilitating installation.
Along the principal direction of the floor panel, a total length of the second material blocks may be less than a total length of the wood blocks.
Along the principal direction of the floor panel, a total length of the second material blocks may be more than 5%, preferably more than 10%, 20%, 30% or 40% of the total length of the floor panel. Typically, the total length of the second material blocks is less than 50% of the total length of the floor panel.
The second material blocks have lower density than said wood blocks and/or lower tensile strength in a direction parallel to said principal fiber directions than said wood blocks.
The second material blocks may comprise expanded polymer material blocks, such as at least one of expanded polyethylene, expanded polypropylene and expanded polystyrene extruded polystyrene foam.
As an alternative or complement, the second material blocks may comprise an engineered wood product.
Non-limiting examples of engineered wood products include fiberboards, chip boards, particle boards, and reconstituted wood.
As yet another alternative or complement, the second material blocks may comprise a non-expanded polymer material comprising filler material.
The wood blocks comprise, or consist essentially of, wood blocks of a wood quality, which is lower than or equal to V according to the Swedish "Gröna boken" ("The Green book") standard of 1960, preferably lower than or equal to VI or lower than or equal to VII. As an alternative, the wood blocks may be of a wood quality which is lower than or equal to B according to the Swedish "Blåa boken" ("The Blue book") standard of 1994, preferably lower than or equal to C or lower than or equal to D. As yet another alternative, the wood blocks may comprise wood blocks of a quality which is lower than or equal to G4-2/G2-2 of the European EN 1611-1 standard of 2000, preferably lower than or equal to G4-3/G2-3 or lower than or equal to G4-4/G2-4.
The wood blocks may also, or as an alternative, comprise, or consist essentially of, wood blocks of a strength class, which is lower than or equal to C18 of the EN 338 standard, preferably lower than or equal to C16 or lower than or equal to C14.
Hence, wood blocks, which are of low or very low quality, and hence cost, may be used to a great extent.
The core layer may further comprise a reinforcing inset portion, which may be provided at a short side edge portion of the floor panel.
Typically, the core layer of the floor panel may consist of about 80-99 % by volume, possibly 90-95 % by volume, of alternating wood and second material blocks. The remainder may consist of, inter alia, inset pieces, adapted to provide specific parts of the locking system.
The second material blocks may be provided with surface coating at an edge portion where said second material blocks are exposed.
Alternatively or as a complement, the second material blocks may present a portion of increased density at an edge portion where said second material blocks are exposed.
The decorative layer may comprise, or consist essentially of, natural wood.
The floor panel comprises a balancing layer, and the core layer is sandwiched between the balancing layer and the decorative layer.
According to a second aspect, there is provided a method of making a floor panel, comprising arranging a plurality of elongate wood blocks side by side in a co-planar manner, with their respective longitudinal directions substantially parallel with each other to form a core layer. The method further comprises providing the core layer with at least a decorative layer to form a panel blank, and cutting the panel blank to form an elongate floor panel blank, such that the longitudinal directions of the wood blocks are substantially perpendicular to a principal direction of the floor panel blank. The method further comprises providing a plurality of second material blocks arranged alternatingly with the wood blocks along the principal direction of the floor panel blank. The second material blocks have lower density than said wood blocks and/or lower tensile strength in a direction parallel to said principal fiber directions than said wood blocks.
The method may further comprise forming locking means along said principal direction of the floor panel blank.

Brief Description of the Drawings

Fig. 1 is a schematic exploded view of a panel blank.
Fig. 2 is a schematic perspective view of a panel blank.
Fig. 3 is a schematic perspective view of a part of a floor panel.
Fig. 4 is a schematic top view of a floor panel.
Fig. 5 is a schematic cross sectional view of a floor panel.
Figs 6a-6c schematically illustrate a method of producing a panel blank.

Description of Embodiments

Fig. 1 is a schematic exploded view of a floor panel blank 1, comprising a decorative layer 13, a core layer 10, 11 and a balancing layer 12. Fig. 2 shows a floor panel blank 1' in an assembled state. The core layer 10, 11 is formed of wood blocks 10 and expanded polymer blocks 11, which are arranged alternatingly along a longitudinal direction L of the floor panel blank. For example, this longitudinal direction of the floor panel blank may be substantially parallel with a principal fiber direction of a wood veneer forming a visually exposed upper surface of the decorative layer 13.
The wood blocks 10 may be substantially elongate, with their respective principal fiber direction substantially coinciding with a respective longitudinal direction I of the respective block 10. A cross section of the wood blocks 10 may present a thickness Tw and a width Ww. The width Ww may be greater than the thickness Tw.
The longitudinal direction I of the wood blocks 10 may extend 90° ± 45° relative to the longitudinal direction L of the floor panel blank. Preferably, the wood blocks extend 90° ± 30°, 90° ± 15°, 90° ± 5° or 90° ± 1° relative to the longitudinal direction of the panel blank.
The wood blocks comprise blocks of any appearance, and for cost reasons, the wood blocks comprise, or consist essentially of, (e.g. consist of at least 50%, at least 70 %, at least 90% or at least 95%) a wood quality lower than or equal to V according to the Swedish "Gröna boken" ("The Green book") standard of 1960, preferably lower than or equal to VI or lower than or equal to VII; lower than or equal to B according to the Swedish "Blåa boken" ("The Blue book") standard of 1994, preferably lower than or equal to C or lower than or equal to D; or lower than or equal to G4-2/G2/2 of the European EN 1611-1 standard of 2000, preferably lower than or equal to G4-3/G2-3 or lower than or equal to G4-4/G2-4.
Preferably, the wood is of quality V or VI according to the "Gröna boken" standard, or of a corresponding quality according to any other standard.
Moreover, the wood blocks may have a strength class lower than or equal to C18 of the EN 338 standard, preferably lower than or equal to C16 or lower than or equal to C14.
The wood blocks may be formed of elongate wood beams, and/or of shorter pieces of wood which have been joined together (e.g. using finger joints, dovetail joints and/or glue).
The expanded polymer blocks 11 may be so-called "rigid polymer foams", which may be defined as foams that have a modulus of elasticity (E) of about 0.02 - 0.4 GPa, preferably of about 0.1-0.4 GPa. The density may be in the area of 20-400 kg/m³, preferably about 10-100 kg/m³, most preferably about 20-50 kg/m³.
As an alternative, the expanded polymer blocks 11 may be, or comprise, so-called "flexible polymer foams", which may be defined as foams that have a modulus of elasticity (E) of about 0.0003 - 0.0015 GPa. The density may be in the area of 5-200 kg/m³.
The expanded polymer blocks 11 may be so-called closed cell expanded polymer or open cell expanded polymer.
Examples of materials include polystyrene, polyurethane, polyolefin (e.g. polyethylene, polypropylene), thermosets (phenolic, melamine, urea or combinations thereof) and polyvinyl chloride (PVC).
The expanded polymer material blocks may comprise additives, such as wood chips, wood particles, wood dust (saw dust, wood flour) or wood fibers; mineral fillers (calcium, dolomite, etc); polymeric fillers (e.g. chunks or particles of recycled polymers, rubbers or rubber-like materials). In any event, the expanded polymer blocks may have such properties as to allow them to be formed by cutting in connection with the forming of the locking system.
The expanded polymer blocks 11 are illustrated as being substantially elongate, with their respective longitudinal direction parallel with the longitudinal directions I of the wood blocks 10. A cross section of the expanded polymer blocks 11 may present a thickness Tp and a width Wp. The width Wp may be greater than the thickness Tp.
The thickness Tw of the wood blocks may typically be on the order of about 5-50 mm, more commonly about 5-25 mm or about 7-15 mm, and most typically about 10 mm.
Typically, the thickness Tw of the wood blocks 10 may be substantially the same, or exactly the same, as the thickness Tp of the expanded polymer blocks 11.
The width Ww of the wood blocks 10 may be greater than the width Wp of the expanded polymer blocks 11. As non-limiting examples, the width Wp of the expanded polymer blocks 11 may be less than about 90%, less than about 80%, less than about 70% or less than about 60% of the width Ww of the wood blocks 10.
The floor panel 1" may thus have a core formed of alternating wood and expanded polymer blocks along substantially its entire length, optionally with the exception of one or both short side edges, which may be provided with a reinforcing inset, which may be formed of wood of a higher quality than that of the wood blocks 10, a different type of wood, and/or of wood having a different fiber direction, e.g. perpendicular to, that of the wood blocks 10. Alternatively, the insets may be formed of another material, such as MDF, HDF, polymer or polymer composite (e.g. fiber reinforced polymer). Each of the insets may extend over less than 15% of the floor panel's 1" length, preferably less than 10%, less than 5% or less than 3% of the floor panel's 1" length.
Such insets may, additionally, or as a complement, be provided for one or both long side edges, in which case the insets would extend along all or part of the long side edge(s), and perpendicular to the principal direction of the floor panel.
Referring to Figs 3 and 4, the floor panel 1" may be provided with a locking system 30, 31, 32, 33 adapted for interconnection of the floor panel 1" with similar or identical floor panels. Such a locking system may be arranged to provide mechanical or form-fit locking horizontally and/or vertically, i.e. the floor panels may be locked together wholly or partially without the use of glue.
In one embodiment, the long side locking system 30, 31 may be identical with the short side locking system 32, 33. In another embodiment, the long side locking system 30, 31 may be different from that of the short side locking system in terms of e.g. geometry and/or mechanical properties of the locking system.
A plurality of different systems for mechanical interconnection of floorboards are known as such, and so are the methods of producing them. Non-limiting examples of such systems are shown in WO94/26999A1 US4,426,820 , DE1211175 , DE19851200C1 , FR2675174 , WO99/66151 , WO97/47834 , JP3169967 , WO96/27721 , GB1430423 , WO02/55809 , US4,819,932 , EP1863984A1 and EP1802827A1 , the entire contents of which documents are hereby incorporated herein by reference.
Hence, further description of the locking system is deemed unnecessary.
Referring to Figs 6a-6c, a method of producing a floor panel 1" is disclosed.
Pre-cut blocks 10 of wood as well as pre-formed (e.g. cut or moulded) blocks 11 of expanded polymer may be arranged on a first sheet, which may be the balancing layer 12 or the decorative layer 13. The first sheet 12, 13 and/or the side of the blocks 10, 11 facing the first sheet may be provided with glue prior to the joining of the blocks 10, 11 to the first sheet 12. Moreover, a second sheet 13 is provided and its side facing the blocks 10, 11 and/or the side of the blocks 10, 11 facing the second sheet are provided with glue, after which the second sheet 13 is joined with the blocks.
The blocks 10, 11 may be arranged so as to abut each other along their longitudinal direction I. Alternatively, a small space in the longitudinal direction L of the floor panel may be provided between the members of each pair of adjacent blocks. The space may be in the order of 0.1-5 mm, preferably 1-3 mm.
After the sheets 12, 13 and blocks 10, 11 have been joined, they may be subjected to pressure, either batchwise or continuously, e.g. by rollers or a belt press. The pressure may be complemented with addition of heat or other means for activating the glue, such as ultrasound, microwaves, etc..
Typically, these steps are performed to provide a blank, which may have a size of on the order of about e.g. 1.2 m x 2.4 m. This blank may then be cut into floor panel blanks 1', i.e. blanks having the general shape of the finished floor panel 1 ", but without any locking system 30, 31, 32, 33 formed along its edges. The floor panel blanks 1' may then be subjected to milling and optionally addition of separate elements (locking tongues, locking elements, locking strips, etc.) to provide the desired locking system 30, 31, 32,33.
The decorative layer 13 may be in the form of a solid wood sheet, which typically has a thickness of about 2-5 mm, most often about 3 mm. The wood sheet may be composed of a single or few wood blocks, or of a plurality of lamellae to form a block pattern on the surface. Typically most, or at least some, of these lamellae are elongate and extend substantially parallel to the longitudinal direction L of the floor panel. Alternatively, some of the lamellae extend perpendicular to the longitudinal direction L of the floor panel, as would be the case with floor panels for providing a so-called Dutch floor pattern.
Alternatively, the decorative layer may be formed of a plurality of layers, such as e.g. a reinforcement layer combined with a thin surface layer, which is laminated or glued to the reinforcement layer. The surface layer may be formed of e.g. a thin (0.5-2 mm) wood veneer, or a laminate, i.e. an artificially patterned (e.g. printed) layer, which may be laminated to, or integrated with, a wear layer, which may comprise a polymer material with fillers and additives for providing a hard surface. The reinforcement layer may be formed of plywood, MDF, HDF or other sheet material.
A decorative layer 13 of wood or wood veneer may be natural, i.e. uncoated, or coated/treated with e.g. lacquer, wax, oil, varnish or any other type of surface finish, such as acrylic or urethane based floor finishes.
The balancing layer 12 may be formed of a thin (0.5-2 mm) sheet of wood or plywood. Alternatively, the balancing layer may be formed of a polymer film, a woven or non-woven sheet, a pulp-based material (such as paper) or other wood-polymer composite material.
The floor panel typically forms part of a set of substantially identical floor panels, which are to be joined together to provide a flooring.
The expanded polymer blocks referred to above may be replaced or complemented with blocks of another material, which may be less costly, have lower density and/or lower tensile strength in the direction which is parallel with the principal direction of the wood fibers of the wood blocks.
Hence, the second material blocks may comprise an engineered wood product.
A first example of such a material is a so-called LDF (low density fiberboard) or VLDF (very low density fiberboard), which may be a board which is formed through moulding or compression moulding of wood chips, particles and/or dust. It is possible to mould such material during wet or moist condition, in which no or very little additional binder need to be added.
For example, an LDF board may be used having a density of 160-500 kg/m³ may be used.
In the alternative, a VLDF board may be used having a density of 200-300 kg/m³. LDF and VLDF boards are known from Rowell, R. et al: "Dimensionally Stabilized Very Low Density Fiberboard", Wood and Fiber Science, 27(4). pp. 428-436 (1995), the entire content of which is hereby incorporated herein by reference.
In yet another alternative, a ULDF (ultra low density fiber) board may be used having a density of 50-200 kg/m³. Such fiber boards are known through Xie, Y. et al: "Manufacture and Properties of Ultra-Low Density foamed Fibreboard from Wood Fibre", BioResources 6(4), 4055-4066 (2011) the entire content of which is hereby incorporated herein by reference.
Hence, fiber boards having low, very low or ultra low density may be provided substantially without binder (wet/moist compression moulding), with binder and/or with additional additives.
It is also possible to replace or complement the expanded polymer material blocks with non-expanded composite polymer material blocks comprising a polymer matrix and fillers, such as e.g. wood chips, wood particles, wood dust (saw dust, wood flour) or wood fibers, mineral fillers (calcium, dolomite, etc).
Exposed portions of second material blocks of wood fiber (e.g. LDF, VLDF, ULDF) or filled polymer material may also be provided with surface treatment in order to improve e.g. strength, friction (reduce) or wear properties. Such treatment may include the application of penetrating or coating forming matter, such as lacquer and/or thermosetting polymers.

Claims

A floor panel, comprising:
a decorative layer (13), and

a core layer (10, 11) arranged below the decorative layer (13) when the floor panel is substantially horizontally oriented, and

a balancing layer, wherein the core layer is sandwiched between the balancing layer and the decorative layer,

wherein the core layer comprises a plurality of wood blocks (10) arranged with their respective principal fiber directions substantially parallel with a plane (So) defined by a major surface of the floor panel and substantially perpendicular to a principal direction (L) of the floor panel, and

a plurality of second material blocks (11), made from a different material than said wood blocks (10),

characterized in that

along the principal direction (L) of the floor panel, the core layer presents alternating portions formed of said wood blocks (10) and of said second material blocks (11),

the second material blocks (11) have lower density than said wood blocks (10) and/or lower tensile strength in a direction parallel to said principal fiber direction than said wood blocks (10),

the wood blocks (10) comprise wood blocks of a wood quality, which is:
lower than or equal to V according to the Swedish "Gröna boken" ("The Green book") standard of 1960, preferably lower than or equal to VI or lower than or equal to VII;

lower than or equal to B according to the Swedish "Blåa boken" ("The Blue book") standard of 1994, preferably lower than or equal to C or lower than or equal to D; and/or

lower than or equal to G4-2/G2-2 of the European EN 1611-1 standard of 2000, preferably lower than or equal to G4-3/G2-3 or lower than or equal to G4-4/G2-4.
The floor panel as claimed in claim 1, wherein along the principal direction (L) of the floor panel, a total length of the second material blocks (11) is less than a total length of the wood blocks (10).
The floor panel as claimed in claim 1 or 2, wherein along the principal direction (L) of the floor panel, a total length of the expanded second material blocks (11) is more than 5%, preferably more than 10%, 20%, 30% or 40% of a total length of the floor panel.
The floor panel as claimed in any one of the preceding claims, wherein the second material blocks comprises expanded polymer material blocks, such as at least one of expanded polyethylene, expanded polypropylene and expanded polystyrene extruded polystyrene foam.
The floor panel as claimed in any one of claims the preceding claims, wherein the second material blocks comprise an engineered wood product.
The floor panel as claimed in any one of the preceding claims, wherein the second material blocks comprise a non-expanded polymer material comprising filler material.
The floor panel as claimed in any one of the preceding claims, wherein the core layer further comprises a reinforcing inset portion.
The floor panel as claimed in any one of the preceding claims, wherein the second material blocks (11) are provided with surface coating at an edge portion where said second material blocks are exposed.
The floor panel as claimed in any one of the preceding claims, wherein the second material blocks (11) present a portion of increased density at an edge portion where said second material blocks are exposed.
The floor panel as claimed in any one of the preceding claims, wherein the decorative layer (13) comprises wood.
The floor panel as claimed in any one of the preceding claims, wherein a thickness (Tw) of the wood blocks (10) is substantially the same, or exactly the same, as a thickness (Tp) of the second material blocks (11)
A method of making a floor panel, comprising:
arranging a plurality of elongate wood blocks (10) side by side in a co-planar manner, with their respective longitudinal directions (I) substantially parallel with each other to form a core layer,

providing the core layer with at least a decorative layer (13) to form a panel blank,

providing the core layer with a balancing layer, such that the core layer is sandwiched between the balancing layer and the decorative layer,

cutting the panel blank to form an elongate floor panel blank, such that the longitudinal directions (I) of the wood blocks are substantially perpendicular to a principal direction (L) of the floor panel blank,

characterized by

providing a plurality of second material blocks (11) arranged alternatingly with the wood blocks (10) along the principal direction (L) of the floor panel blank,

said second material blocks having lower density than said wood blocks and/or lower tensile strength in a direction parallel to said principal fiber directions than said wood blocks (10),

the wood blocks (10) comprise wood blocks of a wood quality, which is:
lower than or equal to V according to the Swedish "Gröna boken" ("The Green book") standard of 1960, preferably lower than or equal to VI or lower than or equal to VII;

lower than or equal to B according to the Swedish "Blåa boken" ("The Blue book") standard of 1994, preferably lower than or equal to C or lower than or equal to D; and/or

lower than or equal to G4-2/G2-2 of the European EN 1611-1 standard of 2000, preferably lower than or equal to G4-3/G2-3 or lower than or equal to G4-4/G2-4.
The method as claimed in claim 12, further comprising forming locking means (30, 31) along said principal direction (L) of the floor panel blank.