Method for producing a laminate, laminate for a piece of furniture, and use of a polyhydroxyalkanoate in the production of a laminate

Abstract

The invention relates to a method for producing a laminate for a piece of furniture, said method comprising the following steps: First, a decorative material is placed on a carrier panel. A composition is applied to the decorative material and / or the carrier panel, wherein the composition comprises a polyhydroxyalkanoate. The composition, the decorative material and the carrier panel are then pressed together to obtain the laminate at a pressing temperature at which the polyhydroxyalkanoate melts at least partially. The invention further relates to a laminate and to the use of a polyhydroxyalkanoate.

Description

[0001] 72P71PCT

[0002] Method for manufacturing a laminate, laminate for a piece of furniture, and the use of a polyhydroxyalkanoate in the manufacture of a laminate.

[0003] The invention relates to a method for producing a laminate for a piece of furniture, a laminate for a piece of furniture obtainable by such a method, and the use of a polyhydroxyalkanoate in the production of a laminate for a piece of furniture.

[0004] Typically, melamine-coated panels are used as a structural material in furniture, for example, furniture for use in offices. These panels consist of a core board pressed with a melamine-impregnated coating paper to form a laminate, increasing the durability and resistance of the core board.

[0005] However, the use of melamine resins has its drawbacks. Melamine resins are produced by the polymerization of melamine with formaldehyde, so if the polymerization is incomplete during the curing process or if the melamine resin degrades later, formaldehyde can be released into the environment. Furthermore, the large-scale production of melamine resins relies on fossil fuels such as natural gas, thus increasing the carbon footprint of the furniture. Additionally, melamine resin does not degrade to a significant extent under either aerobic or anaerobic environmental conditions, which is a disadvantage if melamine-containing furniture is disposed of improperly. Moreover, surfaces made with melamine resins cannot be removed from or repaired without damaging the underlying substrate.

[0006] The object of the invention is to provide a surface for furniture that avoids the disadvantages of melamine resins and, in particular, can be obtained from sustainable raw material sources and is biodegradable.

[0007] The object of the invention is achieved by a method for producing a laminate for a piece of furniture, the method comprising the following steps: First, a decorative material is placed on a substrate. A composition, comprising a polyhydroxyalkanoate, is applied to the decorative material and / or the substrate. Subsequently, the composition, the decorative material, and the substrate are pressed together at a pressing temperature at which the polyhydroxyalkanoate at least partially melts, thus obtaining the laminate.

[0008] The invention is based on the fundamental idea of ​​using a polyhydroxyalkanoate as a resin-forming component to bond the decorative material and the substrate, thereby avoiding or at least reducing the use of melamine resins in furniture production. It has been found that polyhydroxyalkanoates are suitable as adhesives in laminates, and analogous processes known from the production of melamine resin-based laminates can still be used. Because the polyhydroxyalkanoate melts at least partially, preferably completely, at the pressing temperature, the decorative material and the substrate are impregnated with the polyhydroxyalkanoate during pressing. Upon cooling of the laminate after pressing, a resin based on the polyhydroxyalkanoate forms, reliably bonding the laminate components together.

[0009] Polyhydroxyalkanoates (also abbreviated as "PHAs") are naturally occurring, water-insoluble, linear biopolymers that are biodegradable and can be produced biotechnologically, for example, using microorganisms such as bacteria. A particular advantage is that biotechnological production can utilize nutrients for the microorganisms as feedstocks for the production of polyhydroxyalkanoates, which are derived from renewable resources. For example, plant and / or animal sugars, short-chain acids and / or alcohols, as well as oils and / or fats are used as feedstock(s). Thus, the use of polyhydroxyalkanoates in laminate production reduces the CO₂ footprint compared to melamine resin-based laminates. Furthermore, because polyhydroxyalkanoates are biodegradable, reliable degradation is possible even in the event of improper disposal at the end of the laminate's service life.

[0010] Furthermore, it was found that the decorative material and the carrier material can be separated again, since the polyhydroxyalkanoate-based resin can be removed by heating it to a detachment temperature without damaging the carrier material.

[0011] The composition is in powder form. This allows for particularly easy application of the composition to the decorative material and / or the substrate, for example, by spreading the powdered composition using a spreading device such as a sieve. The polyhydroxyalkanoate can be a homopolymer or a copolymer comprising repeating units of the formula [-O-CHR-CH2-CO-], where R is H or a carbon residue with one to 13 carbon atoms, or a mixture of such homopolymers or copolymers. The choice of the R residue makes it possible to precisely control the melting temperature of the polyhydroxyalkanoate, with higher melting temperatures generally resulting from the use of R residues with more carbon atoms in the side chain.

[0012] Preferably, R is equal to H or a carbon residue with one to 6 carbon atoms, particularly preferably equal to H or a carbon residue with one to 3 carbon atoms.

[0013] For example, the polyhydroxyalkanoate is selected from the group consisting of poly(3-hydroxypropionate), poly(3-hydroxybutyrate), poly(3-hydroxyvalerate), poly(3-hydroxyhexanoate), mixtures and copolymers thereof.

[0014] The polyhydroxyalkanoate is particularly preferred as a poly(3-hydroxybutyrate) homo- or copolymer.

[0015] A particularly preferred copolymer, which according to the invention is used as a polyhydroxyalkanoate in the composition, is poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), which is also known as PHB-H.

[0016] The polyhydroxyalkanoate can consist of a single one of the previously mentioned polyhydroxyalkanoates.

[0017] In particular, the polyhydroxyalkanoate is a semi-crystalline polyhydroxyalkanoate. Using a semi-crystalline polyhydroxyalkanoate allows for the particularly reliable production of laminates in which the polyhydroxyalkanoate retains its transparent character, resulting in no or only negligible color changes to the decorative material.

[0018] The polyhydroxyalkanoate can have a melt flow rate (MFR) of 10 g / 10 min or less (165 °C / 2.16 kg), particularly a melt flow rate in the range of 2 to 10 g / 10 min. At higher melt flow rates, excessive flow of the polyhydroxyalkanoate may occur during melting, making process control more difficult. Furthermore, the melt flow rate is dependent on the molecular weight of the polyhydroxyalkanoate, with a lower melt flow rate generally associated with a lower molecular weight.

[0019] The melt flow index can be determined according to DIN EN ISO 1133.

[0020] The basic composition can consist of polyhydroxyalkanoate.

[0021] It is also possible that the composition contains additives with which the properties of the composition and the manufactured laminate can be specifically adjusted.

[0022] In one variant, the composition contains a plasticizer, specifically selected from the group of citric acid residues, in particular triethyl citrate, tributyl O-acetylcitric acid, or a combination thereof. Citric acid esters can be produced from renewable raw materials and are biodegradable. Furthermore, it has been found that such plasticizers also contribute to a lower flammability of the laminate.

[0023] When a combination of several compounds is used as plasticizers, these can be sprayed on sequentially or first compounded into a plasticizer and applied simultaneously. The composition can contain 10 to 35 wt% of the plasticizer, based on the total weight of the composition. A plasticizer content exceeding 35 wt% in the composition has an increasingly detrimental effect on the mechanical properties of the laminate.

[0024] The pressing temperature is particularly in the range of 120 to 185 °C, preferably in the range of 150 to 175 °C. This ensures, on the one hand, that a particularly high proportion of the polyhydroxyalkanoate melts, thereby ensuring particularly good wetting of the decorative material and / or the substrate, and on the other hand, prevents the polyhydroxyalkanoate from beginning to decompose during the pressing process.

[0025] The pressing time depends in particular on how the pressing temperature is achieved when pressing the composition, decorative material, and substrate. For example, a laminate precursor consisting of the composition, decorative material, and substrate can be placed on a heated press plate, especially a preheated one, and pressed on the press plate while maintaining the laminate structure. It is understood that a counter-pressure press plate, which is also preferably heated, can be used for pressing.

[0026] If the laminate precursor is brought to pressing temperature using a heated press plate, the substrate is dried, particularly before producing the laminate precursor, to prevent the formation of waves or bubbles in the laminate during pressing, or the partial degradation of the polyhydroxyalkanoate or the resin formed from the polyhydroxyalkanoate through hydrolysis. Drying takes place at a drying temperature in the range of 180 to 220 °C and / or for a drying time of 5 to 15 minutes. Pressing the laminate precursor into the laminate using a heated press plate is characterized by a short pressing time. For example, the composition, the decorative material, and the substrate—i.e., the laminate precursor—are pressed together on the press plate for a pressing time of 30 seconds to 5 minutes, particularly in the range of 1 to 3 minutes.The pressing time may include the time to heat a structural sheet, which is used to bring the press plate to the desired temperature.

[0027] Alternatively, the laminate precursor can be heated in an oven and then pressed. Heating the laminate precursor in an oven generally requires a longer process time than pressing with a heated press plate, but allows for gentle heating of the laminate precursor to achieve particularly good wetting of the decorative material and / or substrate.

[0028] It is understood that before the period during which the composition, decorative material and substrate are kept at the pressing temperature, a heating phase must be carried out in order to warm the composition, decorative material and substrate to the pressing temperature.

[0029] When an oven is used to heat the composition, decorative material, and substrate to the pressing temperature, the composition, decorative material, and substrate are heated at a rate of 1 to 10 K / min. This allows the components, especially the substrate, to dehydrate due to the slowly rising temperature during the heating phase, preventing the decorative material from forming waves or bubbles on the substrate. A prior drying step for the substrate is unnecessary in this method. The heating phase can last from 10 to 30 minutes when using an oven, with the duration depending primarily on the required pressing temperature and the desired heating rate.

[0030] If the laminate precursor is brought to the pressing temperature using a heated press plate, the heating rate at which the laminate precursor is brought to the pressing temperature is higher than when using an oven, so that the heating phase in this variant can be a few seconds, for example in the range of 5 to 30 seconds.

[0031] The substrate can be a wood-based panel, in particular particleboard or MDF. The type of substrate is primarily determined by the type of furniture in which the laminate is intended to be used. Polyhydroxyalkanoates have proven to be chemically compatible with wood-based panels and can be removed from such panels without damage by targeted heating.

[0032] The decorative material can be a decorative foil or decorative paper. Decorative paper, in particular, has a basis weight of 20 to 100 g / m². 2Decorative films and papers of this type are commercially available in both printed and unprinted forms, resulting in a high degree of variability in the selection of decorative material and thus in the appearance of the finished laminate. Polyhydroxyalkanoates exhibit high compatibility and wettability with corresponding decorative materials.

[0033] The decorative material can have several layers, for example, consisting of a sequence of several decorative papers and / or papers, wherein at least two decorative papers or papers within the sequence have different basis weights. In this context, "paper" refers to paper that is not printed with a pattern. To further protect the laminate from mechanical stress and environmental influences, it can be coated with a clear varnish.

[0034] The object of the invention is further achieved by a laminate for a piece of furniture, obtainable by a method as described above, comprising a carrier board and a decorative material connected to the carrier board, wherein the carrier board and the decorative material are connected to each other by means of a resin based on a polyhydroxyalkanoate.

[0035] The advantages, features, and properties of the previously described method according to the invention apply analogously to the laminate according to the invention, and vice versa, and reference is made to the preceding explanations. In particular, the same materials can be used in the laminate that were previously described in connection with the method according to the invention.

[0036] In particular, the laminate is preserved using the method described above.

[0037] The laminate according to the invention is characterized by its lower CO2 footprint compared to melamine resin-based laminates, as well as its biodegradability.

[0038] Furthermore, it is possible to remove the decorative material from the substrate without damage by heating the laminate to a release temperature at which the polyhydroxyalkanoate-based resin at least partially remelts. In this way, the decorative material can be replaced without having to replace the entire laminate or the piece of furniture in which it is used. The release temperature is particularly high than the pressing temperature used during the laminate's production and can be a temperature at which the resin has already partially decomposed.

[0039] For example, the release temperature is 185 °C or higher, particularly 190 °C or higher. It is understood that the release temperature is chosen such that the substrate material is not damaged at that temperature.

[0040] Furthermore, the object of the invention is solved by the use of a polyhydroxyalkanoate in the production of a laminate for a piece of furniture.

[0041] In particular, the polyhydroxyalkanoate is used to produce a resin based on the polyhydroxyalkanoate for bonding decorative material and the substrate of the laminate.

[0042] The laminate in question is specifically a laminate as described above.

[0043] The advantages, features, and properties of the previously described method and laminate according to the invention apply analogously to the use according to the invention and vice versa, and reference is made to the preceding explanations. In particular, the same materials can be used in the laminate that were previously described in connection with the method and laminate according to the invention.

[0044] Further features and characteristics of the invention will become clear from the following description of exemplary embodiments and experimental examples, which should not be understood in a restrictive sense.

[0045] Manufacturing examples: For the manufacturing examples, a raw chipboard of emission type El with a thickness of 16 mm and a weight of 640 kg / m² was used in each case. 3A substrate was provided. A decorative material was then applied to the particleboard. This decorative material was subsequently sprinkled with a composition containing a polyhydroxyalkanoate.

[0046] The laminate precursor produced in this way was placed in a Bürkle press, which had a heated press plate for heating the precursor. The precursor was heated to a pressing temperature, pressed into a laminate at this temperature for a defined period, and then cooled to room temperature in the press.

[0047] Table 1 lists the materials used and the process parameters, whereby, in the case that a sequence of several decorative papers was used in the decorative material, the sequence is given starting from the substrate material.

[0048] The press plate temperature, i.e., the temperature to which the heated press plate was heated, is always higher than the actual pressing temperature at which the laminate precursor was pressed into laminate.

[0049] Table 1: Structure and manufacturing conditions of laminates according to the invention.

[0050] Bluepha® PHA BP330-05 (available from Bluepha, China) is a formulation that uses poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) as a polyhydroxyalkanoate. Citrofol® AI Extra (available from Jungbunzlauer, Switzerland) is triethyl citrate.

[0051] Helian BP are decorative papers and are available from Schattdecor.

[0052] the pressing times

[0053] In examples 1 to 3, the same structure of carrier material and decorative material was used in combination with a composition based on the same polyhydroxyalkanoate, which were joined together for different pressing durations.

[0054] In all examples 1 to 3, a stable laminate was obtained. a plasticizer

[0055] In Example 1, a plasticizer was added in addition to the polyhydroxyalkanoate, with the composition containing 15 wt% of the plasticizer, based on the total weight of the composition.

[0056] In this case too, a stable laminate with a transparent paper layer was obtained. Neither waves nor bubbles appeared in the decorative material.

[0057] Preliminary tests on resistance and removability

[0058] To investigate the properties of the laminate produced according to the invention, preliminary tests were carried out with laminates that were not heated using a heated press plate and pressed into laminate in the previously described press system, but were heated and pressed in a laboratory setup in an oven. In all preliminary tests, a raw particleboard of emission type El with a thickness of 16 mm and a weight of 640 kg / m² was also used. 3 It is used as a carrier board onto which the respective decorative materials are applied.

[0059] Removability of the decorative material

[0060] In a preliminary test, a decorative material consisting of a sequence of Helian BP 330 (476 g / m²) was used. 2 ), paper (80 g / m²) 2 ) and Helian BP 330 (476 g / m²) 2) sprinkled with a composition consisting of Bluepha ® PHA BP330-05, heated in an oven for a period of 60 minutes using a maximum oven temperature of 190 °C, and pressed.

[0061] After cooling, the laminate produced in this way was heated again to a peeling temperature of 185 °C until liquid resin became visible on the laminate and the decorative material was then removed from the substrate using a scraper.

[0062] The decorative material could be completely removed from the backing board without damaging the backing board. the laminate

[0063] In a second preliminary test, a decorative material consisting of a sequence of Helian BP 330 (313 g / m²) was used. 2 ) and paper (80 g / m²) 2) sprinkled with a composition consisting of Bluepha ® PHA BP330-05, heated in an oven for a period of 60 minutes using a maximum oven temperature of 190 °C, and pressed.

[0064] Several laminates were produced according to this variant in order to test their resistance to mechanical and chemical stresses.

[0065] One of the produced laminates was tested for its peel strength from the substrate in accordance with EN 311:2002, whereby a circularly milled surface is covered with steel stamps and these are loaded on a universal tensile-pressure machine until breakage, and the maximum force achieved and the fracture pattern are assessed.

[0066] Another of the produced laminates was tested for abrasion resistance using a TABER® Abraser in accordance with EN 14322:2017 and EN 14323:2017. The test was conducted according to the criteria of DGUV 315-410, Class 3 A. In this test, the sample rotates under two grinding drums in contact with sandpaper, and the abrasion pattern is assessed according to the specifications of EN 14323:2017.

[0067] Stain resistance to liquid media in accordance with EN 14322:2017 was tested by application, dwell time and subsequent

[0068] The removal of defined test media (coffee and acetone) from different sections of the laminate surface was tested. The remaining residues were assessed according to EN 14323:2017.

[0069] It turns out that the laminates according to the invention have excellent properties with regard to removability as well as mechanical and chemical stresses.

Claims

Patent claims 1. Method for manufacturing a laminate for a piece of furniture, comprising the following steps: - Placing a decorative material on a backing board; - Applying a composition to the decorative material and / or the substrate, wherein the composition comprises a polyhydroxyalkanoate; and - Pressing of composition, decorative material and substrate while maintaining the laminate at a pressing temperature at which the polyhydroxyalkanoate at least partially melts.

2. The method of claim 1, wherein the composition is in powder form.

3. A method according to claim 1 or 2, wherein the polyhydroxyalkanoate is a homopolymer or a copolymer comprising repeating units of the formula [-0- CHR-CH2-CO-], wherein R is equal to H or a carbon residue with one to 13 carbon atoms, or a mixture of such homopolymers or copolymers.

4. A method according to any of the preceding claims, wherein the polyhydroxyalkanoate has a melt flow index MFR (165 °C / 2.16 kg) of 10 g / 10 min or less.

5. A method according to any of the preceding claims, wherein the composition contains a plasticizer, wherein the plasticizer is selected in particular from the group of citric acid esters, in particular triethyl citrate, tributyl o-acetylcitric acid or a combination thereof.

6. The method of claim 5, wherein the composition contains 10 to 35 wt.% of the plasticizer, based on the total weight of the composition.

7. Method according to one of the preceding claims, wherein the pressing temperature is in the range of 120 to 185 °C, preferably in the range of 150 to 175 °C.

8. Method according to one of the preceding claims, wherein a laminate precursor consisting of the composition, the decorative material and the carrier board is placed on a heated press plate and pressed on the press plate to obtain the laminate.

9. Method according to claim 8, wherein the laminate precursor is pressed onto the press plate for a pressing time in the range of 30 seconds to 5 minutes.

10. Method according to claim 8 or 9, wherein the carrier board is dried before producing the laminate precursor.

11. Method according to one of the preceding claims, wherein the support board is a wood-based panel, in particular a particleboard or an MDF panel.

12. Method according to any of the preceding claims, wherein the decorative material is a decorative film or a decorative paper, in particular wherein the decorative paper has a basis weight in the range of 20 to 100 g / m² 2 has.

13. Method according to one of the preceding claims, wherein the laminate is provided with a clear varnish.

14. Laminate for a piece of furniture, obtainable by a method according to one of the preceding claims, comprising a carrier board and a decorative material bonded to the carrier board, wherein the carrier board and the decorative material are bonded together by means of a resin based on a polyhydroxyalkanoate.

15. Use of a polyhydroxyalkanoate in the manufacture of a laminate for a piece of furniture.

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