A decorative thermosetting laminate for floors

(54) NAME Decorative tempering laminate with extremely increased abrasion resistance (56) PUBLICATIONS REFERRED TO: EP Al 249 583 (B32B 29/00), DE 2 362 645 (B32B 5/06),

US 3,294,622 (428-203) (57) SUMMARY:

The invention relates to a decorative thermosetting laminate with extremely increased abrasion resistance comprising a backing layer and at least two paper resin impregnated with this firmly bonded sheet. These sheets are provided with the same pattern. The paper material in these pattern sheets is transparent. The pattern sheets are placed so over one another that the pattern portions of the sheets at least substantially, but preferably completely coincide with each other, whereby the pattern upon wear of a pattern layer will be repeated in the next pattern layer.

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The present invention relates to a thermosetting laminate with extremely increased wear resistance.

Decorative thermosetting laminates are well known and are used, among other things. as cladding material on walls, cupboards and benches, on tables and other furniture and as flooring material.

Such laminates are often made up of two to seven kraft paper sheets impregnated with phenol-formaldehyde resin, a single-color or decorated pattern sheet impregnated with melamine-formaldehyde resin, and a fine so-called overlay sheet of α-cellulose impregnated with melamine-formaldehyde resin.

The overlay sheet is designed to protect the pattern sheet from abrasion. In some cases, the overlay sheet is demolished.

There are also laminates consisting of a chipboard or wood fiber board carrier provided with such a decor sheet and possibly an overlay sheet. These sheets can be laminated to the support under heat and pressure. If you use only one pattern sheet and no overlay sheet, the pattern sheet can instead be glued to the wearer.

The laminate has many good properties. However, it has been found that there is a great need to improve the abrasion resistance of the laminates subjected to extreme wear. This applies mainly to laminate flooring, but to a certain extent also laminate to countertops and tables.

Attempts have been made in the past to improve the abrasion resistance of these laminates by adding small, hard particles of, for example, alumina already in the manufacture of the overlay paper of α-cellulose.

The particles have thereby been sprayed over a layer of wet α-cellulose fibers on the wire of a paper machine. particles

467 150 then distribute more or less irregularly throughout the fiber layer. Some of the particles even pass through the wire. Thus, in the resulting overlay paper, the hard particles will disperse in an uncontrolled manner. It is impossible to obtain a uniform distribution of the hard particles on the surface of the paper with this known method, where they give the greatest effect against abrasion.

In other words, the obtained laminates containing such overlay sheets have an uneven quality in terms of abrasion resistance.

Our Swedish patent application 8800550-9 describes a decorative thermosetting laminate with a durable surface layer. That laminate comprises at least one sheet of paper or surface superficially located in the laminate which, prior to the lamination step, is impregnated with thermosetting resin, preferably melamine resin, coated with small, hard particles evenly distributed over the resin coated surface, after which the resin is dried.

The particle-coated sheet of paper is then made up of the pattern paper or the so-called overlay paper, which is usually made of α-cellulose. In some cases, both overlay paper and pattern paper that are coated in this way can be used.

In that invention, only one pattern sheet is used in the laminate in the usual way.

The laminate described has a considerably higher wear resistance than the previously known decorative laminates. Often, however, there is a need to be able to make even more durable laminates, among other things. for floors in public premises, elevators etc.

It has not previously been considered possible to satisfy this need. However, by means of a revolutionary innovation, it has now been possible to produce one according to the present invention

467 150 decorative thermosetting laminates with extremely increased abrasion resistance, including a backing layer and at least two, hardened plastic impregnated patterned sheets of paper, which are bonded to the paper, the paper material of these patterns being transparent.

The laminate is characterized in that the pattern sheets are provided with the same pattern, and that the sheets are placed so over one another that the pattern parts of the sheets at least mainly, but preferably completely coincide with each other, whereby the pattern upon wear of a pattern layer will be repeated in the next pattern layer.

The use of two or more pattern sheets in a decorative thermosetting laminate according to the invention is quite ingenious. Before, only one pattern sheet has always been used. Various attempts have been made in various ways to protect the pattern of the sheet from abrasion, but once the pattern has worn down, the laminate has been replaced.

In order for the invention to work, a new paper in the pattern sheets is required in this context. The paper must thus be transparent. Preferably it is made of α-cellulose.

When the pattern on the first transparent pattern paper in the laminate is worn out, the pattern in the next pattern paper will be visible through the transparent first pattern paper, etc. In this way, the wear will proceed through the laminate without noticing that the pattern is worn down.

The conventional pattern papers used so far in the manufacture of thermosetting laminates cannot be used in accordance with the invention. They are not transparent but are made of a simpler type of paper containing filler etc.

This plain non-transparent paper would thus hide the pattern of an underlying pattern sheet and thus destroy the continuity of the pattern through the different pattern sheets.

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To get the best aesthetic effect, the patterns in the different pattern sheets should be placed so that the pattern details on the different pattern sheets coincide completely with each other.

When using two or more pattern sheets according to the invention, the pattern can also be arranged so as to have a depth effect, a three-dimensional appearance.

In some cases, an acceptable quality of the pattern in the laminate can be obtained even if the patterns in the different pattern sheets do not exactly coincide but are slightly offset relative to each other.

The pattern sheets can also be monochromatic. Of course, the need to place the pattern sheets with coincident patterns does not go away. Of course, the very increased wear resistance is achieved even when using single-colored pattern sheets.

The transparent paper used for the pattern sheets is preferably calendered or otherwise prepared to enable printing of the pattern.

The laminate may also contain natural, thermosetting impregnated, transparent paper sheets. These can be placed between the pattern sheets. Often there is also at least one unpainted transparent sheet of paper that is called an overlay at the top of the laminate.

The patterned and un-patterned, transparent α-cellulose paper, respectively, can be treated to give the laminate extra durability. Thereby, the paper can be impregnated with a thermosetting resin, preferably melamine-formaldehyde resin, coated with small, hard particles evenly distributed over the resin-coated surface, after which the resin is dried.

The hard particles can be made up of many different materials. Especially suitable is the use of silica, alumina and / or silicon carbide. Mixture of two or more materials is

467 150 thus possible.

The size of the particles is important for the end result. If the particles are too large, the laminate surface becomes rough and uncomfortable. Too small particles, on the other hand, can cause poor abrasion resistance. Preferably, the particles have an average particle size of about 1 - 80 µm, preferably about 5 - 60 µm.

Other methods of increasing the wear resistance of the sheets of paper can also be used within the scope of the invention.

The substrate layer may consist of a chipboard or a wood fiber plate, whereby the transparent pattern layers and any unpainted transparent paper sheets are joined to the substrate layer by means of heat and pressure or by gluing. The substrate layer may also consist of one or more thermosetting impregnated sheets of paper which are joined to each other and the other sheets of paper by curing under heat and pressure. Typically, phenol-formaldehyde resin is used for impregnating the sheets of paper in the backing layer.

Of course, the invention is not limited to laminates made up of sheets of paper containing melamine-formaldehyde resin and phenol-formaldehyde resin. Other thermosets, such as polyester resin, are also conceivable.

The very bottom pattern sheet in the laminate may consist of a conventional non-transparent paper, which may be single-colored or patterned.

The invention is explained in more detail in connection with the following embodiment. Example 1 shows the preparation of a conventional decorative thermosetting laminate without special abrasion preventive additives. According to Example 2, a specially known overlay paper is used, where small, hard particles have been added to the paper fibers already during the papermaking. Example 3 illustrates a method according to an embodiment of the invention according to

467 150 the Swedish patent application 8800550-9.

Examples 4 and 5 show a variation of the method of Example 1, where a larger number of so-called α-cellulose overlays are used. Examples 1-5 thus relate to comparative experiments outside the scope of the invention. Examples 6-9 illustrate various embodiments of the laminate according to the invention.

Example 1

A roll of transparent so-called α-cellulose overlay paper with a basis weight of 40 g / m was impregnated with melamine formaldehyde resin solution to a resin content of 70% by weight based on dry impregnated paper. The impregnated paper web was then continuously fed into a heating furnace, where the solvent was evaporated while the resin partially cured to the so-called B-stage. The resulting product is normally called prepreg.

The paper web was cut into sheets of suitable length. The sheets were then automatically stacked on top of each other.

A roll of conventional non-transparent so-called pattern paper with card printing and a surface weight of 80 g / m was treated in the same way as the overlay paper. The resin content was 48% by weight based on dry impregnated paper.

A roll of kraft paper having a basis weight of 170 g / m was also treated in the same way, except that the resin was phenol-formaldehyde resin instead of melamine-formaldehyde resin. The resin content was 30% by weight based on dry impregnated paper.

Between two press plates were placed three pieces of the above phenolic resin impregnated prepreg sheets (so-called stump paper), a pattern paper and an overlay paper. These papers were pressed in a conventional multistage press at a pressure of 90 kp / cm and one

467 150 temperature of 145 ° C for 45 minutes to a homogeneous decorative laminate.

The abrasion resistance of the resulting laminate was tested according to ISO standard 4568 / 2-83 using an apparatus called Taber Abraser model 503. According to that standard, the wear of the pattern layer on the finished laminate is measured in two steps. In step 1, the so-called IP point (initial point) is measured, where initial wear and tear occurs.

In step 2, the so-called EP point (end-point) is measured, where 95% of the pattern is worn.

Furthermore, the above ISO standard stipulates that the number of turns achieved with the test machine in step 1 and step 2 is added, and then the sum obtained is divided by 2. This gives the 50 percentage point for wear, which is normally reported in norms and specific pressures.

However, in this and following examples, only the IP point is used.

When testing the above laminate, a value of 200 rpm was obtained for the IP point, which is normal for a decorative laminate without reinforcing the wear layer.

Example 2

In a paper mill, an α-cellulose overlay paper having a surface weight of 40 g / m was produced by discharging slurry α-cellulose fibers from an outlet box into the wire of a paper machine. On the top of the wet fiber layer, alumina particles were applied at an amount of 3 g / m and with an average particle size of about 50 μπι.

In the continued production of the overlay paper, the hard particles were more or less irregularly distributed throughout the paper. Some particles ended up near the surface, some near the middle and some in the bottom of the paper. Some particles passed

467 150 even all the way through the fiber layer and out through the wire. Thus, they were not left in the finished paper.

The overlay paper produced was impregnated with the same amount of melamine-formaldehyde resin and then treated otherwise in the same manner as in Example 1.

A laminate was prepared with the same number of sheets and structure as described in Example 1. The pressing was also done under the same conditions.

The abrasion resistance of the resulting laminate was tested in the same manner as in Example 1. An IP value of 600 rpm was obtained.

Example 3

The procedure of Example 1 was repeated with the difference that immediately after the impregnation of the transparent α-cellulose paper_t but prior to drying, the top of the paper alumina particles were applied at an amount of 3 g / m and with an average particle size of about 50 µm.

Thus, the hard alumina particles were applied to the melamine-formaldehyde resin not yet dried.

In the subsequent drying, the grains were enclosed in the resin layer and consequently concentrated to the surface of the prepreg prepared. The abrasion resistance of the produced laminate was tested in the same way as in Example 1. An IP value of 2000 rpm was measured.

Example 4

The procedure of Example 1 was repeated with the difference that instead of using only an α-cellulose sheet, 2 sheets, 3 sheets, and up to 10 sheets were used.

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The abrasion resistance of the obtained laminates was tested in the same manner as in Example 1.

The following values ​​were obtained:

For a sheet of α-cellulose

For two sheets of α-cellulose

For three sheets of α-cellulose

For six sheets of α-cellulose

For ten sheets of α-cellulose

IP = 200 rpm

IP = 450 rpm

IP - 900 turns

IP = 1300 rpm

IP = 5200 rpm

Wear resistance thus increases with increased number of α-cellulose sheets.

However, the pattern of the decorative decorative laminates was no longer appealing. The more α-cellulose sheets placed on each other, the more obscure and unclear the underlying pattern sheet appeared.

Therefore, the decorative laminates produced did not meet the pattern quality requirement. In addition, the abrasion resistance did not become sufficiently high to permit the use of the laminate in an extremely abrasion-sensitive environment.

Example 5

The procedure of Example 4 was repeated except that instead of using α-cellulose sheets of Example 1, α-cellulose sheets of Example 3 were used.

Decorative laminates were prepared according to Example 1, but with a sheet of α-cellulose with hard particles of Example 3, two sheets, 3 sheets, etc. up to 10 sheets.

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The abrasion resistance of the obtained laminates was tested in the same manner as in Example 1.

The following values ​​were obtained:

For one sheet of α-cellulose with For two sheets of α-cellulose with For three sheets of α-cellulose with For six sheets of α-cellulose with

<td>hard</td><td>grain</td><td>IP = 2,000 rpm</td>

<td>hard</td><td>grain</td><td>IP = 6,000 rpm</td>

<td>hard</td><td>grain</td><td>IP = 9,000 rpm</td>

<td>hard</td><td>grain</td><td>IP = 20,000 rpm</td>

IP = 40,000 rpm

For ten sheets of a-cellulose with hard grains

Thus, the abrasion resistance is increased dramatically by increasing the number of hard-grained α-cellulose sheets.

However, the more α-cellulose sheets placed on each other, the more obscure and unclear appeared in the underlying pattern sheet.

The decorative laminates produced met very stringent wear resistance requirements, but they did not meet the pattern quality requirement due to the blur.

Example 6

A roll of transparent paper of a-cellulose calendered to a Bekktal of about 100 seconds and with a surface weight of 40 g / m was provided with pattern printing using the so-called Rotary Screen method.

Another such roll of paper was provided with pattern printing by means of gravure printing.

The two pattern-printed paper rolls were impregnated with a melamine-formaldehyde resin solution to a resin content of 45% by weight based on dry impregnated paper.

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The two impregnated paper rolls were then continuously fed into a heating furnace, where the solvent was evaporated while the resin partially cured to the so-called B-stage. The resulting product is normally called prepreg.

The paper webs were cut into sheets of suitable length. The sheets were then automatically stacked on top of each other.

The obtained pattern sheets printed by the Rotary Screen method were then combined with the natural transparent α-cellulose sheets containing hard grains prepared in Example 3.

The sheets were placed on top of each other so that every other sheet was a natural α-cellulose sheet containing hard grains and every other sheet was pattern sheets.

The pattern sheets were placed so that corresponding pattern pieces in the different sheets ended up directly above each other. Thus, the same pattern was repeated exactly right through all the pattern sheets.

The following combinations were pressed in the same manner as in Example 1 together with three pieces of phenol-formaldehyde resin impregnated seam papers at the bottom:

a) 3 natural α-cellulose sheets with hard grains and 3 pattern sheets were rotated on top of each other, each of each kind and with a natural α-cellulose sheet containing hard grains at the top.

b) in the same way as a), but with 5 natural α-cellulose sheets with hard grains and 5 pattern sheets alternated, each of each kind and with a natural α-cellulose sheet containing hard grains at the top.

c) in the same way as a), but with 10 natural α-cellulose sheets with hard grains and 10 pattern sheets alternated, each of each kind and with a natural α-cellulose sheet containing hard grains at the top.

The abrasion resistance of the resulting decorative laminates was tested

467 150 in the same manner as in Example 1.

The following values ​​were obtained:

a) 3 + 3

b) 5 + 5

c) 10 + 10

IP = 8,000 rpm

IP = 20,000 rpm

IP = 40,000 rpm

In all the alternatives, significantly higher abrasion resistance was obtained than with previously known decorative thermosetting laminates. However, options b) and c) provided completely outstanding abrasion resistance.

In terms of design, a pattern that was fully approved was obtained. It had a profound effect that was completely new to this type of product.

The laminate is very suitable for floors, where the wear is extremely large. Through the above-mentioned pattern-matched acquisition of the pattern sheets, the original pattern will be maintained throughout the entire life of the floor despite the wear and tear of its surface.

Example 7

The procedure of Example 6 was repeated except that the pattern sheets printed with gravure printing were used. The same values ​​were obtained for abrasion resistance as in the example

6th The patterns were as fine as those of the laminates prepared according to Example 6.

Example 8

A roll of calendered transparent paper of α-cellulose with a surface roughness according to Bekk of about 100 sec was provided with pattern printing using the so-called Rotary Screen method.

Another similar paper roll was pattern printed using the gravure printing method.

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The two pattern-printed paper rolls were impregnated with a melamine-formaldehyde resin solution to a resin content of 45% by weight based on dry impregnated paper. Immediately after the impregnation, but before drying the melamine-formaldehyde resin, hard alumina particles having an average particle size of 45 µm were applied to the top of the paper in an amount of 3 g / m².

The two impregnated paper rolls were then continuously fed into a heating furnace, where the solvent was evaporated while the resin partially cured to the so-called B-stage. The resulting product is normally called prepreg.

The paper webs were cut into sheets of suitable length. The sheets were then automatically stacked on top of each other.

The obtained pattern sheets printed by the Rotary Screen method were then combined with a natural, transparent α-cellulose sheet containing hard particles prepared according to Example 3.

The pattern sheets and the transparent α-cellulose sheet containing hard particles were pressed in the same manner as in Example 1, along with three downstream phenol-formaldehyde resin impregnated seam papers. The following combinations were pressed:

a) on top of a natural, transparent α-cellulose sheet containing hard particles and underneath 3 pieces of pattern sheets containing hard particles. The pattern sheets were placed so that corresponding pattern pieces in the different sheets ended up directly above each other.

b) in the same way as a), but with 5 pattern sheets.

c) in the same way as a), but with 10 pattern sheets.

The abrasion resistance of the resulting decorative laminates was tested in the same manner as in Example 1. The following values ​​were obtained:

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<td>a)</td><td> 1 + 3</td><td>IP = 7,500 rpm</td>

<td>b)</td><td> 1 + 5</td><td>IP = 18,000 rpm</td>

<td>c)</td><td> 1 + 10</td><td>IP = 39,000 rpm</td>

The abrasion resistance remained largely unchanged compared to the result of the corresponding experiments according to Example 6, even though all except a natural α-cellulose sheet with hard particles were eliminated, the other results were also unchanged in comparison with Example 6.

Because so many natural cellulose sheets were demolished, the content of melamine resin in the surface of the laminate decreased to more than half compared to the procedure of Example 6. This means that the laminate does not become so brittle and the tendency of the laminate to become unclean (capped) decreases.

Example 9

The procedure of Example 6 was repeated except that the pattern sheets printed with gravure printing were used. The same results as in Example 8 were obtained in all respects.

The invention is not limited to the embodiments shown, since these can be modified in various ways within the scope of the invention.

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