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Title:
COMPLETELY RECYCLABLE SANDWICH BOARDS WITH FOAMED CORE
Document Type and Number:
WIPO Patent Application WO/2024/099486
Kind Code:
A1
Abstract:
Completely recyclable sandwich boards contain in their structure lightweight core (1) with bulk density of 30 to 300 kg.m-3 and thickness of 3 to 300 mm, either of reoriented polypropylene foam in the form of sheet made of strips, profiles or strings which has direction of orientation with the best mechanical properties transformed into the thickness direction of sandwich board or from single-layer or multi-layer polypropylene foam in the form of board created from strips, profiles or strings. This lightweight core (1) is both sides (I, II) covered by reinforcing layers (2) based on polypropylene reinforcing grid, polypropylene biaxially oriented film, polypropylene fabric, polypropylene laminate or polypropylene film reinforced by short fibers. Leveling layer (3) consisting of single-layer, two-layer, three-layer or five-layer polypropylene film with thickness of 0.05 to 2.00 mm can be attached to the reinforcing layer at least on one side (I) or (II). Furthermore, adhesive layers (5, 6, 7) based on hot-melt polyolefinic adhesive with melting point of 80 to 160 °C can be inserted between lightweight core layer (1), reinforcing layers (2), leveling layers (3) or eventually covering layers (4).

Inventors:
KRATKY ONDREJ (CZ)
Application Number:
PCT/CZ2023/050076
Publication Date:
May 16, 2024
Filing Date:
November 03, 2023
Export Citation:
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Assignee:
SPUR A S (CZ)
International Classes:
B32B5/18; B32B5/24; B32B7/02; B32B27/06; B32B27/08; B32B27/12; B32B27/32
Foreign References:
DE19959652A12001-06-13
US20190291393A12019-09-26
US20050019549A12005-01-27
US20070114816A12007-05-24
Attorney, Agent or Firm:
GÖRIG, Jan (CZ)
Download PDF:
Claims:
P A T E N T C L A I M S Completely recyclable sandwich boards with foamed core characterized by the fact that their structure contains lightweight core (1) either of reoriented polypropylene foam in the form of board made of strips, profiles or strings with bulk weight of 30 to 300 kg.nT 3 and thickness of 3 to 300 mm which has the direction of orientation with the best mechanical properties transformed into the thickness direction of sandwich board or of single-layer or multi-layer polypropylene foam, in the form of board made of strips, profiles or strings with bulk weight of 30 to 300 kg.nT3 and thickness of 3 to 300 mm, while this lightweight core (1) is covered on both sides (I, II) by reinforcing layers (2) based on polypropylene reinforcing grid, polypropylene biaxially oriented foil, polypropylene fabric, polypropylene laminate or polypropylene foil reinforced by short fibers. Completely recyclable sandwich boards according to claim 1, characterized by the fact that the polypropylene foam of the lightweight core (1) contains 1 to 30 wt.% flame retardant based on magnesium hydroxide, aluminum hydroxide or compounds of halogens, phosphorus or nitrogen, especially ammonium polyphosphate. Completely recyclable sandwich boards according to claim 1, characterized by the fact that the reinforcing layer (2) based on polypropylene reinforcing grid consists of one or more grid layers of unidirectionally oriented fibers layered in two or more directions with total weight of 10 to 2000 g.n 2 possibly connected by fusible polyolefinic intermediate layer. Completely recyclable sandwich boards according to claim 1, characterized by the fact that the reinforcement layer (2) based on polypropylene biaxially oriented film is formed by one or more layers of biaxially oriented film with total weight of 10 to 4000 g.nT2, optionally connected by fusible polyolefinic intermediate layer. Completely recyclable sandwich panels according to claim 1 characterized by the fact that the reinforcing layer (2) based on polypropylene fabric consists of one or more layers of polypropylene self-reinforcing reinforcing fabric with total weight of 80 to 3000 g.m'2, optionally connected by hot melt polyolefin interlayer or one or more layers of polypropylene fabric with total weight of 80 to 4000 g.m'2 possibly connected by fusible polyolefin interlayer. Completely recyclable sandwich boards according to claim 1 characterized by the fact that the reinforcement layer (2) based on polypropylene laminate is composed of polypropylene laminate with surface weight of 100 to 3000 g.m'2 from multiple layers of self-reinforcing polypropylene reinforcing fabrics, polypropylene laminate with surface weight of 100 to 3000 g.m'2 from multiple layers of unidirectionally oriented polypropylene self-reinforced thin films rotated by 90° - with composition of 0°/90° or polypropylene laminate with surface weight of 100 to 4000 g.m'2 from multiple layers in one direction of oriented polypropylene thin films mutually rotated - with a 0°/90° composition. Completely recyclable sandwich boards according to claim 1, characterized by the fact that the reinforcing layer (2) based on polypropylene film reinforced by short or long fibers is formed by one layer of polypropylene film with surface weight of 100 to 4000 g.m'2, reinforced by short or long fibers made of glass, carbon, aramid, kevlar or basalt in proportion of 10 to 60 wt.%, possibly further reinforced by mineral filler such as talc or wollastonite in proportion of 10 to 60 wt.% or with one layer of polypropylene film from renewable sources or recycled raw materials with surface weight of 100 to 4000 g.m'2 reinforced by natural short or long fibers from abaca, hemp, flax, jute, coconut, silk, cotton, com or ramie in proportion of 10 to 40 wt.%. Completely recyclable sandwich boards according to claim 7, characterized by the fact that the polypropylene film reinforced by short or long fibers of the reinforcing layer (2) further contains 1 to 40 wt.% of flame retardant based on magnesium hydroxide, aluminum hydroxide or compounds of halogens, phosphorus or nitrogen, especially ammonium polyphosphate. Completely recyclable sandwich boards according to claims 1 to 8 characterized by the fact that to the structure containing lightweight core (1) made of polypropylene foam which is on one or both sides covered by reinforcing layers (2) can be at least on one side (I) or (II) attached leveling layer (3) consisting of single-layer polypropylene film with thickness of 0.05 to 2.00 mm, two-layer film of type A-B, three-layer film of type A-B-A or five-layer film of type A-C-B-C-A, each with thickness of 0.05 to 2 .00 mm, where layer B is made of polypropylene, layer A is an adhesive layer of polyolefin with melting point of 80 to 160°C, and layer C is an adhesive bridge between layers A and B. Completely recyclable sandwich boards according to claims 1 to 8 characterized by the fact that to the structure containing the lightweight core (1) made of polypropylene foam which is on one or both sides covered by reinforcing layers (2) can be at least on one side (I) or (II) attached covering layer (4) based on decorative and/or protective single - layer or multi-layer film, mesh, grid, mat or polypropylene fabric with thickness of 0.01 to 5.00 mm, possibly containing flame retardant or with defined coefficient of friction or with defined surface energy on the basis of fabric or knitted fabric from polypropylene fibers with surface weight of 50 to 2000 g.m'2, on the basis of woven, non-woven, knitted or combined fabric from polypropylene with surface weight of 50 to 5000 g.m'2 such as interior or exterior carpets and artificial lawns, based on nonflammable polypropylene film with thickness of 0.05-5.00 mm containing 1 to 40 wt.% of flame retardant such as magnesium hydroxide, aluminum hydroxide or compounds of halogens, phosphorus or nitrogen, especially polyphosphate ammonium or based on injected chemically or thermally reinforced non-woven fabric made of polypropylene fibers with surface weight of 50 to 2000 g.m'2. Completely recyclable sandwich boards according to claims 1 to 10 characterized by the fact that their structure can contain adhesive layers between the layers of the lightweight core (1), reinforcing layers (2), leveling layers (3), or covering layers (4) (5, 6, 7) based on hot-melt polyolefin adhesive with melting point of 80 to 160°C in the form of film, grid, web, powder or melt of surface weight 20 to 500 g.m'2, hot-melt polyurethane or moisture-crosslinkable polyolefin adhesive of surface weight 20 up to 500 g.m'2, one- or two-component polyacrylate or cyanoacrylate glue or glue based on polyether or polyurethane polymers terminated with silyl groups of surface weight 20 to 500 g.m'2.
Description:
COMPLETELY RECYCLABLE SANDWICH BOARDS WITH FOAMED CORE

Field of Invention

The technical solution is focused on fully recyclable sandwich panels with a lightweight core. Layers of these boards are primarily composed of polypropylene or polyolefin layers which offers the possibility of full recyclability after the end of the board’s life cycle, primarily by common mechanical recycling methods - crushing, grinding and regranulation into recycled polypropylene fully usable for reprocessing by common plastic technologies (extrusion, pressing, injection, etc.) for new plastic products. Obviously, homogeneity of the polymer allows thermal or chemical recycling as well.

Current State of the Art

Sandwich panels with a lightweight core based on foamed polyolefin are currently known for applications in vehicle interiors and above all for sports equipment applications.

Japanese patent application No. 2015112867 relates to a method of manufacturing ceiling panels for vehicles by vacuum forming of sandwich panels containing core of lightweight polypropylene covered on both sides by surface layers of compact polypropylene.

The subject of US patent No. 7,063,769 is a multilayer sandwich board for a water or snow surfboard. On three-layers core composed of lightweight polyethylene with closed cells, visual and protective films are laminated on one and other side, respectively. The three-layer core of the board increases impact resistance during surfing on water, snow or land sliding, while the surface films provide users better comfort and high safety due to smooth surfaces of both sides of the board.

The sports board for sledding or surfing is also subject of two other US patents No. 7,578,254 and No. 7,503,820. The multi-layered board structure with a composite core made of lightweight polyethylene with laminated polystyrene lightweight layer contains reinforcing elements for mechanical board reinforcement and other visual to functional (slides) layers, which are also polyethylene based.

US Patent No. 7,150,666 relates to a sports board composed of an elongated closed cell expanded polyolefin foam. US Patent Application 2007059515 is focused on board for sliding on water, snow and ground, which is made as a laminated board with a sandwich construction including top plastic visual film with printed graphics, reinforcing layer, at least three-layer lightweight core, a leveling layer and a sliding layer. Individual layers of the sandwich construction are bonded by thermoplastic connecting layers with excellent cohesive characteristics. The three-layer reinforced lightweight core contains: (i) thermoplastic bonding layer with a thickness of 0.02 to 0.10 mm, a stronger layer of closed-cell polypropylene foam forming the top layer of the core with thickness in the range of 1.5 to 5 mm and density in the range of 64 to 144 kg.nT 3 , (ii) again thermoplastic bonding layer having thickness of 0.02 to 0.10 mm, a core of closedcell low-density polyethylene foam having thickness ranging from 20 to 80 mm and density ranging from 24 to 64 kg.nT 3 , (iii) another thermoplastic bonding layer with a thickness of 0.02 to 0.10 mm, and again more rigid layer of closed-cell polypropylene foam forming the lower layer of the lightweight core, which has thickness in the range of 1.5 to 5 mm and density in the range of 64 to 144 kg.nT 3 equipped with a thermoplastic bonding layer with a thickness of 0.02 to 0.10 mm.

The sports board for sledding or surfing according to US patent No. 7,246,568 contains multi-layer laminated lightweight core of polyolefin low density foam, combined with reinforcing elements for mechanical stiffening of the board. Reinforcing elements in the form of strips or bars (not plates) are made of lightweight polyolefin or polystyrene with reoriented structure. The front part of the board made from the same polyolefin low density foam is attached to the foam core and ensures flexibility, shock absorption and better control of the board. The integrity of the reinforced core composite and entire board is realized by the application of the upper and lower film made of lightweight polyethylene. The upper part of the sled is finished by graphic film and the lower part is covered by slide based on a smooth polyethylene film.

US Patent Application 2006228539 relates to a water, snow and ground sliding board that has a multi-layered core of polyethylene foam material with different densities in three or more layers. Specifically, it can be a layer of polyethylene high density foam having particular density in the range of 80 to 160 kg.nT 3 and thickness of 1 to 5 mm, a layer of ethylene vinyl acetate high density foam having stiffness in the range of 26 to 65 degrees and thickness of 1 to 5 mm or layer of polypropylene high density foam that has density in the range of 48 to 160 kg.nT 3 and thickness of 1 to 5 mm. To increase adhesion between the core layers, adhesive interlayers based on thermoplastics are inserted. The sports board according to US patent No. 7,303,454 contains, similarly to the sports board according to US patent No. 7,150,666, core of oriented closed-cell polyolefin foam, an upper polyolefin film layer with thickness less than the thickness of the core and a middle metallocene polyolefin layer with a thickness less than the thickness of the core. Except the core of the final product, also lateral struts in the form of strips/bars are made of multi-layer lightweight structure. Lightweight core materials are polyethylene foam, polypropylene foam, polyethylene vinyl acetate copolymer foam, polyethylene-polypropylene copolymer foam, and polyethylene- styrene copolymer foam.

Chinese utility model 207207306 relates to a multi-layer aluminum-plastic composite board having 14mm-thick lightweight polyethylene core and an aluminum alloy top layer. On the cover layer paint or protective film slowing down the corrosion of the aluminum surface and achieve a smooth surface with an aesthetic appearance can be applied.

The lack of known sandwich boards is the fact that the necessary strength of the lightweight core is achieved by complicated and often multi-layer structure with reinforcement and adhesive interlayers often with different composition. This fact, together with the use of other layers of different composition - polymer inhomogeneity in the complete construction of the product, as in the case for example, with a number of well-known sports boards - makes recyclability after the end of the life cycle of such sandwich board very complicated.

Summary of the Invention

Fully recyclable sandwich panels with a lightweight core according to the presented technical solution make a significant contribution to eliminating the above-mentioned lacks. Its principle is based on the fact that structure of the boards contains lightweight core of reoriented polypropylene foam in the form of a board made of strips, profiles or strings with a bulk weight of 30 to 300 kg.nT 3 and thickness of 3 to 300 mm, which has the direction of orientation with the best mechanical properties transformed into the thickness direction of a sandwich board or from single-layer or multi-layer polypropylene foam, in the form of a board made of strips, profiles or strings, with a bulk weight of 30 to 300 kg.nT 3 , and a thickness of 3 to 300 mm. This lightweight core is then both sides covered by reinforcing layers based on a polypropylene reinforcing grid, polypropylene biaxially oriented film, polypropylene fabric, polypropylene laminate or polypropylene film reinforced with short fibers. Polypropylene foam of lightweight core can optionally contain 1 to 30 wt.% flame retardant based on magnesium hydroxide, aluminum hydroxide or compounds of halogens, phosphorus or nitrogen, especially ammonium polyphosphate. A reinforcing layer based on a polypropylene reinforcing grid is preferably formed by one or more grid layers of unidirectionally oriented fibers placed in two or more directions with total surface weight of 10 to 2000 g.m' 2 , possibly connected by a fusible polyolefin interlayer.

The reinforcement layer based on biaxially oriented polypropylene film is one or more layers of biaxially oriented film with total surface weight of 10 to 4000 g.m' 2 , which can be optionally connected by a fusible polyolefinic intermediate layer.

The reinforcing layer based on polypropylene fabric is preferably formed by one or more layers of self-reinforcing polypropylene (srPP) reinforcing fabric with total surface weight of 80 to 3000 g.m' 2 , optionally connected by fusible polyolefinic interlayer or one or more layers of polypropylene fabric with total surface weight of 80 up to 4000 g.m' 2 , possibly connected by fusible polyolefin interlayer.

The reinforcement layer based on polypropylene laminate can be made of polypropylene laminate with surface weight of 100 to 3000 g.m' 2 composed of multiple layers of selfreinforcing polypropylene (srPP) reinforcing fabrics. Another variant is reinforcing layer made of polypropylene laminate with surface weight of 100 to 3000 g.m' 2 composed of multiple layers of unidirectionally oriented polypropylene self-reinforced (srPP) thin films rotated by 90° to each other - with composition of 0790° or polypropylene laminate with surface weight of 100 to 4000 g.m' 2 composed of multiple layers of unidirectionally oriented polypropylene (MOPP) thin films mutually rotated - with a composition of 0790°.

The reinforcing layer based on polypropylene film reinforced by short or long fibers can be formed by one layer of extruded polypropylene film with surface weight of 100 to 4000 g.m' 2 , reinforced by short or long fibers of glass, carbon, aramid, kevlar, basalt in ratio of 10 to 60 % wt., possibly further reinforced by a mineral filler such as talc or wollastonite in the proportion of 10 to 60 % wt. Another variant is reinforcing layer consisted of one layer of extruded polypropylene film from renewable sources or recycled raw materials with surface weight of 100 to 4000 g.m' 2 , reinforced by abaca, hemp, flax, jute, coconut, silk, cotton, com or ramie natural short or long fibers in proportion of 10 to 40 wt.% A polypropylene film reinforced by short or long fibers can further contain 1 to 40 wt.% flame retardant based on magnesium hydroxide, aluminum hydroxide or compounds of halogens, phosphorus or nitrogen, especially ammonium polyphosphate.

To the structure containing lightweight core made of polypropylene foam, which is on one or both sides covered by reinforcing layers, leveling layer consisted of single-layer polypropylene film with a thickness of 0.05 to 2.00 mm, a two-layer film of type A-B, a three- layer A-B-A type film or a five-layer A-C-B-C-A type film, each with thickness of 0.05 to 2.00 mm, where layer B is made of polypropylene, A is an adhesive layer of polyolefin with melting temperature of 80 to 160°C, and layer C is an adhesive bridge between the layers A and B can be placed.

Furthermore, cover layer based on decorative and/or protective single-layer or multilayer film, mesh, grid, mat or fabric can be attached to the structure containing lightweight polypropylene foam core, which is one or both sides covered by reinforcing layers, at least on one side covering layer based on a decorative and/or protective single-layer or multi-layer film, mesh, grid, mat or polypropylene fabric with a thickness of 0.01 to 5.00 mm, possibly containing a flame retardant, possibly with a defined coefficient of friction or with a defined surface energy, on the basis of fabric or knitted fabric from polypropylene fibers with surface weight of 50 to 2000 g.m' 2 , on the basis of woven, non-woven, knitted or combined polypropylene textiles with surface weight of 50 to 5000 g.m' 2 , such as interior or exterior carpets and artificial lawns, based on non-flammable polypropylene film with a thickness of 0.05-5.00 mm containing 1 to 40 wt.% of flame retardant such as magnesium hydroxide, aluminum hydroxide or compounds of halogens, phosphorus or nitrogen, especially ammonium polyphosphate or on the basis of injected chemically or thermally reinforced non-woven fabric made of polypropylene fibers with surface weight of 50 to 2000 g.m' 2 is attached.

Fully recyclable sandwich boards can in the structure between lightweight core layers, reinforcing layers, leveling layers, or cover layers contain adhesion layers based on a hot-melt polyolefinic adhesive with a melting point of 80 to 160°C in the form of film, grid, web, powder or melt with surface weight 20 to 500 g.m' 2 , hot-melt polyurethane or polyolefin adhesive postprocess crosslinkable by moisture with surface weight 20 to 500 g.m' 2 , one- or two-component polyacrylate or cyanoacrylate adhesive or adhesive based on polyether or polyurethane polymers terminated by silyl groups in the form of a liquid substance in the viscosity range 15 to 300,000 mPa.s (at temperature of 25°C), applied in one layer of 20 to 500 g.m' 2 .

As already mentioned, the main benefit of the technical solution is the fact that the composition of the sandwich boards is designed as fully recyclable after the end of the board’s life cycle. This may primarily concern recyclability by conventional mechanical recycling methods - i.e. by crushing, grinding and regranulation into polypropylene recyclate which is fully usable for reprocessing by common plastic technologies into plastic products by extrusion, pressing, injection molding, etc. However, polymer homogeneity enables also thermal or chemical recycling. In addition to recyclability, other advantages of sandwich boards according to the presented technical solution include their very low weight, wide temperature range of use, resistance to weather, resistance to chemical influences, thermal insulation properties, excellent mechanical properties and low toxicity of flue gases during combustion.

Sandwich boards according to the technical solution can be used in furniture industry for indoor and outdoor furniture, in the construction industry for the construction of walls, ceilings and floors, in freight transport for cabinet superstructures and floors, for the construction of interiors and exteriors of buses, trains, ships, airplanes, vans cars, camper vans etc. The boards can be bent under heat, they have excellent strength during mechanical joining (retaining the screw) and their edges can be laminated with plastic furniture edges. The density of the boards ranges from 32 kg.nT 3 to 600 kg.nT 3 . The plates are produced in rectangular formats in the form of flat or curved surfaces. The boards have length of up to 20000 mm, width of up to 3000 mm and thickness of 3 to 320 mm.

Brief Description of Drawings

Depper explanation of the technical solution principle is explain on the attached drawing where Fig. 1 represents the composition of the layers of the sandwich board according to the technical solution.

Examples of Invention Realization

Example 1

The sandwich board in the exemplary embodiment has the following composition of layers (see Fig. 1):

Example 2

The sandwich board in the exemplary embodiment has the following composition of layers (see Fig. 1):

Example 3

The sandwich board in the exemplary embodiment has the following composition of layers (see Fig. 1):

Example 4

The sandwich board in the exemplary embodiment has the following composition of layers (see Fig. 1):

Example 5

The sandwich board in the exemplary embodiment has the following composition of layers (see Fig. 1):

Example 6

The sandwich board in the exemplary embodiment has the following composition of layers (see Fig. 1):

Example 7

The sandwich board in the exemplary embodiment has the following composition of layers (see Fig. 1):

Example 8

The sandwich board in the exemplary embodiment has the following composition of layers (see Fig. 1):

Example 9

The sandwich board in the exemplary embodiment has the following composition of layers (see Fig. 1):

Industrial Applicability

Sandwich boards according to the technical solution can be used in the furniture industry for indoor and outdoor furniture, in the construction industry for the construction of walls, ceilings and floors, in freight transport for cabinet superstructures and floors, for the construction of interiors and exteriors of buses, trains, ships, airplanes, vans cars, camper vans etc. The composition of sandwich boards is designed with regard to its full recyclability after the end of the life cycle of the board.