SPACER FOR SEPARATING SURFACES OF ADJACENT ARTICLES

TECHNICAL FIELD

The present invention relates to a spacer for separating surfaces of adjacent articles according to claim 1 , to a method of producing a spacer according to claim 10, and to the use of foamed polyurethane for producing an adherent layer of a spacer according to claim 15.

PRIOR ART

When transporting fragile articles such as glass spacers are commonly arranged between adjacent articles in order to protect the articles against damage. It is normally desirable that the spacers adhere to the articles to prevent movement during transportation so as to ensure proper spacing of the articles. To this end spacers known in the prior art often comprise a polyvinyl chloride (PVC) foam being arranged on a substrate, and which PVC foam is configured to adhere to the surface of the articles. However, PVC foams are associated with several disadvantages. For instance, PVC is particularly harmful to the environment due to its chlorine compounds. Furthermore, it behaves badly in the so-called down-cycling process because it must be burned, i.e. a recycling of PVC is not or only very hardly possible. In addition, the PVC foam usually comprises many plasticizers. The plasticizers can migrate in the article to be protected and might deteriorate the surface thereof. In addition, the shelf life of spacers made out of PVC is short because plasticizers migrate out, so the spacers are not adhering anymore to the articles after about six months after their production.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a spacer that overcomes the drawbacks of the prior art. In particular, it is an object to provide a spacer that is more sustainable. This object is achieved with a spacer according to claim 1. In particular, a spacer for separating surfaces of adjacent articles is provided, wherein the spacer comprises at least one adherent layer and at least one substrate. The adherent layer is arranged on the substrate and is configured to adhere to a surface of an article. The substrate is bio-based and the adherent layer comprises or consists of foamed polyurethane.

The substrate being bio-based preferably comprises or consists of one or more renewable components. In other words, the bio-based substrate preferably comprises or consists of one or more components of biological origin. Moreover, and as compared to PVC foams, the foamed polyurethane (or Pll foam) is more environmentally friendly. As such, the spacer according to the invention is seen as being sustainable.

Hence, the spacer according to the invention is configured to be arranged between surfaces of adjacent articles, wherein the adherent layer adheres to one of the surfaces. The substrate is preferably configured non-adherent, i.e. the substrate preferably has nonclinging tendencies.

It should be noted that the spacer can comprise one or more adherent layers. Said one or more adherent layers can be arranged immediately one above another or spaced apart from one another. In the latter case, it is preferred that one or more intermediate layers are arranged between the adherent layers. Conceivable intermediate layers are for instance an adhesive layer or an adhesive tape layer. Conceivable adhesive layers are classical pressure sensitive adhesives, such as waterborne acrylates, solvent based adhesives, rubber based hotmelts or silicones. Conceivable adhesive tape layers are two adhesive layers with at least one carrier in-between, and wherein said carrier is a plastic film, paper, non-woven, scrims, or the like. It is likewise conceivable that the spacer comprises one or more substrates. For instance, two substrates and two adherent layers can be present, wherein the substrates and the adherent layers are arranged alternately. Statements regarding one adherent layer likewise apply to the presence of two or more adherent layers and vice versa. Statements regarding one substrate likewise apply to the presence of two or more substrates and vice versa.

The substrate preferably comprises or consists of cork and/or a fiber-based product such as paper, cardboard, or wood, and/or of felt and/or of bioplastics and/or of renewable plastics. That is, the substrate can comprise or consist of cork, i.e. the phellem layer of bark tissue. Preferred corks are agglomerated cork and/or recycled cork.

However, it is likewise preferred that the substrate comprises or consists of at least one fiber-based product such as a cellulose-fiber product, for instance a paper-based product or a wood-based product.

Preferred paper-based products are paper and cardboard. Various types of cardboard are conceivable such as card stock, paperboard, corrugated fibreboard, cardboard honeycomb, etc.

Preferred wood-based products are wood, preferably light weight balsa wood.

Preferred bioplastics are polysaccharide-based bioplastics such as starch-based plastics or cellulose-based plastics.

Further preferred bioplastics are aliphatic biopolyesters such as polylactic acid (PLA), poly- 3-hydroxybutyrate (PHB) or polyhydroxybutyrate-co-valerate (PHBV).

Preferred renewable plastics are bio-polyethylene or bio-polypropylene.

Furthermore, the substrate can comprise or consist of one or more of the above components. For instance, the substrate can consist of cork. Alternatively, the substrate can consist of cork and a renewable plastics such as pieces of cork being embedded in biopolyethylene, etc.

The substrate and/or the adherent layer are preferably recycled components such as recycled cork or recycled renewable plastics as the substrate and recycled polyurethane foam as the adherent layer.

Moreover, in the event that the spacer comprises two or more substrates said substrates can be the same or different from one another. For instance, two substrates being made of cork can be present. Alternatively, one substrate being made of cork and another substrate being made of bio-polyethylene can be present, etc. The foamed polyurethane preferably comprises at least one polyol component C1 , and wherein the polyol component C1 comprises at least one polyol C1-1 and/or at least one polyol C1-2 and/or at least one polyol C1-3. The polyol C1-1 is preferably a bio-based polyol and/or an ether based polyol and/or an ester-based polyol and/or an ether-ester based polyol and/or a linear polyol and/or a branched polyol and/or an oil-based polyol and/or mixtures thereof. The polyol C1-2 is preferably a bio-based polyol and/or an ether based polyol and/or an ester-based polyol and/or an ether-ester based polyol and/or a linear polyol and/or a branched polyol and/or an oil-based polyol and/or mixtures thereof. The polyol C1- 3 is preferably a polyol having a molecular weight in the range of 50 g/mol to 250 g/mol and/or an alkanediol. That is, the polyol C1-3 preferably is a low molecular weight polyol.

Hence, the adherent layer preferably comprises one or more polyols, particularly preferably one or more bio-based polyols.

A bio-based polyol preferably comprises or consists of one or more renewable components. In other words, the bio-based polyol preferably comprises or consists of one or more components of biological origin.

To this end it is particularly preferred that the bio-based polyol is based on rape oil, sunflower oil, soya bean oil, and castor oil.

It is furthermore preferred that the polyols are commercially available polyols such as Neukapol® polyols from Altropol Kunststoff GmbH, Deutschland. For instance, Neukapol® PN 1582 and/or Neukapol® 9502 and/or Neukapol® PN 9506 from Altropol Kunststoff GmbH could be used, although other such polyols are likewise conceivable. That is, the polyols can be bio-based or "green" polyols, and wherein said polyols are preferably copolymers based on naturals oils extracted from rape oil, sunflower oil, soya bean oil, and castor oil that are possibly further functionalized to achieve desired properties.

The polyol C1-1 and the polyol C1-2 can be the same or different from one another.

The polyol C1-1 preferably serves as a so-called backbone polyol. The polyol C1-2 preferably serves as a so-called crosslinker polyol. The polyol C1-3 preferably serves as a so-called chain-extender polyol. A backbone polyol is understood as comprising long chains that are essentially liner. The crosslinker polyol is understood as being capable of creating side links (also called cross-links) between the long chains of the backbone polyol. The chain-extender polyol is understood as linking two or more long chains of the backbone polyol together in order to create even longer lengths of these chains.

The polyol component C1 preferably comprises between 60 % by weight to 95 % by weight such as between 70 % by weight to 85 % by weight and most preferably about 78 % by weight of the polyol C1-1 per total weight of the polyol component C1.

The polyol component C1 preferably comprises between 5 % by weight to 30 % by weight such as between 10 % by weight to 20 % by weight and most preferably about 16 % by weight of the polyol C1-2 per total weight of the polyol component C1.

The polyol component C1 preferably comprises between 0 % by weight to 10 % by weight such as between 1 % by weight to 5 % by weight, for instance about 2 % by weight of the polyol C1-3 per total weight of the polyol component C1.

The polyol C1-1 preferably has a functionality between 2 to 4, preferably between 2 to 3. Additionally or alternatively, the polyol C1-1 preferably has a molecular weight between 500 g/mol to 10'000 g/mol, more preferably between 1'000 g/mol to 6'000 g/mol. Additionally or alternatively, the polyol C1-1 preferably has a viscosity between 20 mPa s to 10'000 mPa s, more preferably between 150 mPa s to 5'000 mPa s. Additionally or alternatively, the polyol C1-1 preferably has a hydroxyl number between 20 to 600, more preferably between 40 to 150.

The polyol C1-2 preferably has a functionality between 2 to 6, more preferably between 3 to 5. Additionally or alternatively, the polyol C1-2 preferably has a molecular weight between 100 g/mol to 1'000 g/mol, more preferably between 150 g/mol to 500 g/mol. Additionally or alternatively, the polyol C1-2 preferably has a viscosity between 20 mPa s to 10'000 mPa s, more preferably between 150 mPa s to 5'000 mPa s. Additionally or alternatively, the polyol C1-2 preferably has a hydroxyl number between 20 to 1'000, more preferably between 250 to 600.

The viscosity was determined with a Brookfield viscosimeter as it is known in the art and/or preferably according to the method of DIN EN ISO 2555.

The foamed polyurethane preferably comprises at least one isocyanate component C2. The isocyanate component C2 preferably comprises at least one aliphatic isocyanate and/or at least one aromatic isocyanate and/or at least one polyisocyanate and/or at least one prepolymer thereof and/or at least one mixture thereof.

Conceivable aliphatic isocyanates are aliphatic diisocyanates such as hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and hydrogenated MDI: 4,4'- diisocyanatodicyclohexylmethane (H12MDI).

Conceivable aromatic isocyanates are aromatic diisocyanates such as methylene diphenyl diisocyanates (MDI), toluene diisocyanates (TDI), p-phenylene diisocyanates (PDI), naphthalene-1 ,5-diisocyanates (NDI) and polymeric methylene diphenyl diisocyanate (PMDI).

Conceivable polyisocyanates are polymeric methylene diphenyl diisocyanate (pMDI), however dimers or trimers of MDI, TDI, etc. are likewise conceivable.

A variety of isocyanate prepolymers are conceivable, wherein these isocyanate prepolymers are preferably long molecules with a few isocyanate groups grafted on the backbone.

A preferred isocyanate prepolymer is prepared by adding isocyanate such as MDI, TDI or pMDI to a polyol, preferably a backbone polyol such as C1-1 , in excess such that essentially all -OH groups react with an isocyanate group. As a result, an isocyanate prepolymer comprising long molecules having between 500 g/mol equivalent weight to 20000 g/mol equivalent weight, more preferably between 2000 g/mol to 5000 g/mol equivalent weight with reactive isocyanate groups is obtained. This results in advantages in the properties of the polyurethane foam such as the polyurethane foam being more flexible and having a higher elongation at break.

The isocyanate component C2 particularly preferably comprises one or more diisocyanates, and in particular one or more aromatic diisocyanates such as MDI or TDI.

A preferred MDI is diphenylmethane-4,4'-diisocyanate, for instance diphenylmethane-4,4'- diisocyanate (32%NCO I 126 g/mol equivalent weight, 200 mPa s). However, other MDI isomers such as diphenylmethane-2,2'-diisocyanate or diphenylmethane-2,4'-diisocyanate are likewise conceivable.

A preferred TDI is a mixture of 80/20 or 65/35 of 2,4- and 2,6-toluenediisocyanates.

However, other TDI isocyanates such as 2,4-TDI only or 2,6-TDI only are likewise conceivable.

The isocyanate component C2 preferably consists of one or more isocyanates such as the aliphatic isocyanate, the aromatic isocyanate, the polyisocyanate, the prepolymer thereof, or the mixtures thereof. That is, it is preferred that one or more of these isocyanates are provided as 100 % by weight per total weight of the isocyanate component C2.

The polyol component C1 and the isocyanate component C2 are preferably provided in a ratio of C1/C2 between 2 to 10, more preferably between 3 to 7. However, it should be noted that various ratios of the polyol component C1 and the isocyanate component C2 are conceivable and depend on the specific formulation of the components C1 and C2.

Additionally or alternatively it is preferred that the polyol component C1 and the isocyanate component C2 are preferably provided in a ratio of 3:1 to 7:1 such as in a ratio of 3:1 to 5:1 .

Furthermore, a mixture of the polyol component C1 and the isocyanate component C2 preferably comprises an isocyanate index between 0.5 to 1.0, more preferably between 0.6 to 0.95 such as between 0.7 and 0.95, and particularly preferably of 0.85. The isocyanate index corresponds to the ratio between the total number of -OH groups in the polyol component C1 and the total number of isocyanate groups in the isocyanate component C2.

The polyol component C1 preferably further comprises at least one foaming agent and/or at least one gelling catalyst and/or at least one blowing catalyst and/or at least one surfactant and/or at least one UV stabilizer and/or at least one tackifier and/or at least one additive.

The foaming agent preferably corresponds to water, such as demineralized water. However, other foaming agents such as chemical foaming agents, e.g. azodicarbonamide or mixtures of sodium bicarbonate and citric acid, or physical foaming agents, e.g. 2-methylbutane, n- pentane, cyclopentane, gases such as CO2 and air, azote, methylene chloride, etc., are likewise conceivable. Besides, it is noted that CFCs and HCFCs such as trichloromonofluoromethane or trichlorotrifluoroethane could be used as well, but are however banned or phased out due to their effect on ozone layer depletion.

The polyol component C1 preferably comprises between 0 % by weight to 10 % by weight, more preferably between 0.2 % by weight to 5 % by weight and most preferred preferably about 0.4 % by weight of foaming agent per total weight of the polyol component C1 .

The gelling catalyst preferably comprises an amine-compound or a metal carboxylate- compound. Preferred amine-compounds comprise tertiary amines.

Preferred tertiary amines are bicyclic amines such as DABCO (1 ,4- diazabicyclo[2.2.2]octane), a monoamine such as dimethylcyclohexylamine, a diamine such as bis(dimethylaminoethyl)ether, polyamines such as N-methyl-N'-(2- dimethylaminoethyl)-piperizine), or amine salts such as DBU-phenate. However, other tertiary amines that are generally known in the field of polyurethane foams such as N,N,N’,N”,N”-pentamethyl-diproylene-triamine (PMDPTA) or N,N-dimethylethanolamine (DMEA), etc. are likewise conceivable.

Preferred metal carboxylates are tin catalysts such as stannous 2-ethyl hexoate, dibutyltin di(lauryl mercaptide) or dibutyltin dilaurate. Other preferred metal carboxylates are potassium carboxylates.

The polyol component C1 preferably comprises between 0 % by weight to 1 % by weight, more preferably between 0.3 % by weight to 0.8 % by weight and particularly preferably about 0.55 % by weight of gelling catalyst per total weight of the polyol component C1 .

The blowing catalyst preferably corresponds to a tertiary amine or a metal carboxylate.

Preferred tertiary amines are bicyclic amines such as DABCO (1 ,4- diazabicyclo[2.2.2]octane), a monoamine such as dimethylcyclohexylamine, a diamines such as bis(dimethylaminoethyl)ether, polyamines such as N-methyl-N'-(2- dimethylaminoethyl)-piperizine), or amine salts such as DBU-phenate. However, other tertiary amines that are generally known in the field of polyurethane foams such as N,N,N’,N”,N”-pentamethyl-diproylene-triamine (PMDPTA) or N,N-dimethylethanolamine (DMEA), etc. are likewise conceivable.

Preferred metal carboxylates are tin catalysts such as stannous 2-ethyl hexoate, dibutyltin di(lauryl mercaptide) or dibutyltin dilaurate.

The polyol component C1 preferably comprises between 0 % by weight to 0.5 % by weight, more preferably between 0.05 % by weight to 0.1 % by weight and particularly preferably about 0.08 % by weight of blowing catalyst per total weight of the polyol component C1.

The surfactant preferably corresponds to an anionic surfactant, a silicone surfactant, or a non-ionic surfactant.

Preferred anionic surfactants are calcium stearate or sulfonated castor oils.

Preferred silicone surfactants are polyalkylsiloxanepolyoxyalkylene copolymers.

A preferred non-ionic surfactant is polyethylene glycol.

The polyol component C1 preferably comprises between 0.5 % by weight to 5 % by weight, more preferably between 1 % by weight to 3 % by weight and particularly preferably about 2 % by weight of surfactant per total weight of the polyol component C1 .

Preferred UV stabilizers are a UV absorber, a radical scavenger, a peroxide decomposer, a hindered amine, or an inorganic UV absorber.

Preferred UV absorbers are benzotriazole such as Tinuvin 1130 (from BASF: a mixture of a) 50% p-[3-(2-H-Benzotriazole-2-yl)-4-hydorxy-5-tert.butylphenyl]- propionic acid- poly(ethylene glycol) 300-ester, b) 38% Bis{p-[3-(2-H-Benzotriazole-2-yl)-4- hydroxy5tert.butylphenyl]-propionic acid}-poly(ethylene glycol) 300 -ester, and c) 12% polyethylene glycol), benzophenone, pigments, oxanilides, or formamidine. Another preferred benzotriazole is Tinuvin 571 (2-(2H-Benzotriazol-2-yl)-6-dodecyl-4- methylphenol).

Preferred radical scavengers and/or peroxide decomposers are phosphites, thiodipropionate secondary antioxidants, organic nickel compounds, or carbon black.

Preferred hindered amines are tetramethyl or pentamethyl piperidines such as Tinuvin 292 (from BASF: a mixture of a) Bis (1 , 2, 2, 6, 6-pentamethyl-4-piperidyl) sebacate and b) Methyl 1 , 2, 2, 6, 6- pentamethyl-4-piperidyl sebacate). Another preferred example is Tinuvin 765 (a mixture of a) Bis(1 ,2,2,6,6-pentamethyl-4-piperidyl)sebacate and b) 1- (methyl)-8- (1 ,2,2,6,6-pentamethyl-4-piperidyl) sebacate.)

Preferred inorganic UV-absorbers are titanium dioxide or zinc oxide. To this end it is particularly preferred that the polyol component C1 comprises a combination of UV stabiliziers, particularly a combination of a UV absorber and a hindered amine.

Other preferred UV stabilizers are a combination of a UV absorber, a hindered amine and an antioxidant such as a primary phenolic antioxidant. An example of such a UV stabilizer is Tinuvin B75, a mixture of i) Irganox 1135 (Benzenepropanoic acid, 3,5-bis(1 , 1 -dimethyl— ethyl)-4-hydroxy-C7-C9 branched alkyl esters) and ii) Tinuvin 571 (2-(2H-Benzotriazol-2- yl)-6-dodecyl-4-methylphenol) and iii) Tinuvin 765 (A mixture of Bis(1 , 2,2,6, 6-pentamethyl- 4-pperidyl)sebacate and 1-(methyl)-8- (1 ,2,2,6,6-pentamethyl-4-pperidyl) sebacate).

The polyol component C1 preferably comprises between 0.5 % by weight to 6 % by weight, more preferably between 1 % by weight to 4 % by weight and particularly preferably about 3 % by weight of UV stabilizer per total weight of the polyol component C1 .

Preferred tackifiers are biobased resins such as rosin esters. For example, ROKRAPOL RK 6587 or BREMAR 9020 from Robert Kraemer GmbH & Co. KG could be used.

The polyol component C1 preferably comprises between 0 % by weight to 20 % by weight, more preferably between 5 % by weight to 15 % by weight and particularly preferably about 10 % by weight of tackifier per total weight of the polyol component C1 .

Preferred additives are an inorganic filler, an antioxidant, processing aids, a release agent, a pigment or a hydrophobic agent.

Preferred inorganic fillers are talcum, kaolin, calcium carbonate, and barium sulfate.

Preferred antioxidants are primary phenolic antioxidants.

Preferred processing aids are lubricants as they are known in the art.

Preferred release agents are mold release agents as they are known in the art.

Preferred pigments are titanium dioxide, for instance in the event that a white colour of the adherent layer is desired. That is, the pigment preferably serves the purpose of a colorant. It should be noted that various pigments or colorants such as dyes are conceivable. Preferred hydrophobic agents are silicone-containing surface additives and Fischer Tropsch wax dispersions.

The polyol component C1 preferably comprises between 0 % by weight to 30 % by weight of additives per total weight of the polyol component C1 are conceivable.

For instance, in the event of the additive being an inorganic filler it is preferred that the polyol component C1 comprises between 15 % by weight to 30 % by weight of inorganic filler per total weight of the polyol component C1.

In the event of the additive being an antioxidant it is preferred that the polyol component C1 comprises between 0 % by weight to 1 % by weight of antioxidant per total weight of the polyol component C1.

A first preferred example of a polyol component C1 comprises:

- 77.94 % by weight of Neukapol® PN 9506 (Altropol Kunststoff GmbH, Deutschland) as the polyol C1-1 , preferably as backbone polyol, per total weight of the polyol component C1 ;

- 15.59 % by weight of Neukapol® PN 1582 (Altropol Kunststoff GmbH, Deutschland) as the polyol C1-2, preferably as crosslinker polyol, per total weight of the polyol component C1 ;

- 0 % by weight of butanediol as the polyol C1-3, preferably as chain extender polyol per total weight of the polyol component C1 ;

- 0.39 % by weight of demineralized water as the foaming agent per total weight of the polyol component C1 ;

- 0.55 % by weight of DABCO 33LV (33% 1 ,4-diazabicyclo[2.2.2]octane diluted in dipropylene glycol) as the gelling catalyst per total weight of the polyol component;

- 0.08 % by weight of DABCO BL11 (70% bis(2-Dimethylaminoethyl) ether in dipolypropylene glycol) as the blowing catalyst per total weight of the polyol component C1 ;

- 2.18 % by weight of calcium stearate as the surfactant per total weight of the polyol component C1 ;

- 2.18 % by weight of hydrohyphenyl benzotriazole such as Tinuvin 1330 (from BASF: a mixture of a) 50% p-[3-(2-H-Benzotriazole-2-yl)-4-hydorxy-5-tert.butylphenyl]- propionic acid-poly(ethylene glycol) 300-ester, b) 38% Bis{p-[3-(2-H-Benzotriazole- 2-yl)-4-hydroxy5tert.butylphenyl]-propionic acid}-poly(ethylene glycol) 300 -ester, and c) 12% polyethylene glycol) as UV stabilizer per total weight of the polyol component; and

- 1.09 % by weight of hindered amine light stabilizer such as Tinuvin 292 (from BASF: a mixture of a) Bis (1 , 2, 2, 6, 6-pentamethyl-4-piperidyl) sebacate and b) Methyl 1, 2, 2, 6, 6- pentamethyl-4-piperidyl sebacate) as UV stabilizer per total weight of the polyol component.

A first preferred example of an isocyanate component C2 comprises:

- 100 % by weight of diphenylmethane-4,4-diisocyanate (MDI) (32%NCO / 126 g/mol equivalent weight) per total weight of the isocyanate component C2.

Said first preferred polyol component C1 and said first preferred isocyanate C2 component are preferably present in a ratio of C1/C2 of 3.8 : 1.

A second preferred example of a polyol component C1 comprises:

- 46.47 % by weight of Neukapol® PN 9506 (Altropol Kunststoff GmbH, Deutschland) as the polyol C1-1 , preferably as backbone polyol, per total weight of the polyol component C1 ;

- 46.47 % by weight of Neukapol® PN 9502 (Altropol Kunststoff GmbH, Deutschland) as the polyol C1-2, preferably as crosslinker polyol, per total weight of the polyol component C1 ;

- 0 % by weight of butanediol as the polyol C1-2, preferably as chain extender polyol, per total weight of the polyol component C1 ;

- 0.46 % by weight of demineralized water as the foaming agent per total weight of the polyol component C1 ;

- 0.74 % by weight of DABCO 33LV (33% 1,4-diazabicyclo[2.2.2]octane diluted in dipropylene glycol) as the gelling catalyst per total weight of the polyol component;

- 0.09 % by weight of DABCO BL11 (70% bis(2-Dimethylaminoethyl) ether in dipolypropylene glycol) as the blowing catalyst per total weight of the polyol component C1 ;

- 1.86 % by weight of calcium stearate as the surfactant per total weight of the polyol component C1 ;

- 2.60 % by weight of hydrohyphenyl benzotriazole such as Tinuvin 1330 (from BASF: a mixture of a) 50% p-[3-(2-H-Benzotriazole-2-yl)-4-hydorxy-5-tert.butylphenyl]- propionic acid-poly(ethylene glycol) 300-ester, b) 38% Bis{p-[3-(2-H-Benzotriazole- 2-yl)-4-hydroxy5tert.butylphenyl]-propionic acid}-poly(ethylene glycol) 300 -ester, and c) 12% polyethylene glycol) as UV stabilizer per total weight of the polyol component; and

- 1.30 % by weight of hindered amine light stabilizer such as Tinuvin 292 (from BASF: a mixture of a) Bis (1 , 2, 2, 6, 6-pentamethyl-4-piperidyl) sebacate and b) Methyl 1, 2, 2, 6, 6- pentamethyl-4-piperidyl sebacate) as UV stabilizer per total weight of the polyol component C1.

This second preferred example of the polyol component C1 is cured with the preferred first example of the isocyanate component C2 given above in a ratio of 3:1, resulting in an isocyanate index of 0.92.

A third preferred example of a polyol component C1 comprises:

- 79.00 % by weight of Neukapol® PN 9506 (Altropol Kunststoff GmbH, Deutschland) as the polyol C1-1 , preferably as backbone polyol, per total weight of the polyol component C1 ;

- 17.80 % by weight of Neukapol® PN 1582 (Altropol Kunststoff GmbH, Deutschland) as the polyol C1-2, preferably as crosslinker polyol, per total weight of the polyol component C1 ;

- 0.39 % by weight of demineralized water as the foaming agent per total weight of the polyol component C1 ;

- 0.47 % by weight of DABCO 33LV (33% 1,4-diazabicyclo[2.2.2]octane diluted in dipropylene glycol) as the gelling catalyst per total weight of the polyol component;

- 0.08 % by weight of DABCO BL11 (70% bis(2-Dimethylaminoethyl) ether in dipolypropylene glycol) as the blowing catalyst per total weight of the polyol component C1 ;

- 1.11 % by weight of calcium stearate as the surfactant per total weight of the polyol component C1 ; and

- 1.15 % by weight of Tinuvin B75 (a mixture of i) 20% Irganox 1135 (Benzenepropanoic acid, 3,5-bis(1 ,1-dimethyl-ethyl)-4-hydroxy-C7-C9 branched alkyl esters) and ii) 40% Tinuvin 571 (2-(2H-Benzotriazol-2-yl)-6-dodecyl-4- methylphenol) and iii) 40% Tinuvin 765 (A mixture of Bis(1 , 2,2,6, 6-pentamethyl-4- piperidyl)sebacate and 1-(methyl)-8- (1 ,2,2,6,6-pentamethyl-4-piperidyl) sebacate)) as UV stabilizer per total weight of the polyol component C1.

This third preferred example of the polyol component C1 is cured with the preferred first example of the isocyanate component C2 given above in a ratio C1/C2 of 4.6, resulting in an isocyanate index of 0.62.

A thickness of the substrate is preferably between 1 millimeter to 50 millimeters, more preferably between 2 millimeters to 15 millimeters. A thickness of the adherent layer is preferably between 0.2 millimeter and 3 millimeters, more preferably between 0.5 millimeter and 2 millimeters.

Said thicknesses are preferably determined with respect to an extension direction of the spacer running from a top side of the spacer to a bottom side of the spacer. The adherent layer and the substrate are preferably arranged above one another with respect to the extension direction. In the event of the spacer comprising one adherent layer being arranged on one substrate, a top surface of the adherent layer provides the top side of the spacer and a bottom surface of the substrate provides the bottom side of the spacer. In use, the top surface of the adherent layer adheres to a surface of a first article and the bottom surface of the substrate rests against a surface of an adjacent second article.

The adherent layer can be directly arranged on the substrate or indirectly arranged on the substrate via at least one adhesive layer. The adhesive layer preferably corresponds to pressure sensitive adhesives, such as waterborne acrylates, solvent based adhesives, rubber based hotmelts or silicones.

A density of the substrate preferably is between 100 kg/m ³ and 500 kg/m ³ , more preferably between 150 kg/m ³ to 350 kg/m ³ . A density of the adherent layer preferably is between 50 kg/m ³ and 500 kg/m ³ , more preferably between 100 kg/m ³ and 300 kg/m ³ .

The adherent layer is preferably configured to exert an adhesion strength between 1 N/25mm and 10 N/25mm, more preferably between 2 N/25mm to 5 N/25mm according to DIN EN 1939:2003.

That is, when the spacer is in use and arranged between two adjacent articles, the adherent layer adheres to the surface of one of the articles with an adhesion strength as just given.

The adherent layer preferably has a Shore Hardness 00 between 10 and 50, more preferably 20 to 40.

In another aspect, a method of producing a spacer for separating surfaces of adjacent articles is provided. The spacer preferably corresponds to a spacer as described above. The method comprises the steps of i) providing at least one adherent layer, and ii) providing at least one substrate. The adherent layer is arranged on the substrate and is configured to adhere to a surface of an article. The substrate is bio-based and the adherent layer comprises or consists of foamed polyurethane.

Any statements made herein regarding the spacer preferably likewise apply to the method of producing the spacer and vice versa.

The adherent layer is preferably manufactured from at least one polyol component C1 and at least one isocyanate component C2. The polyol component C1 and the isocyanate component C2 are preferably generated separately in a first step and are mixed preferably in a mixer in a subsequent second step.

To this end it is preferred that the polyol component C1 and the isocyanate component C2 are generated separately, in particular stocked separately in separate vessels or the like in a first step and that these components are then separately conveyed to a mixer in order to be mixed with one another.

The mixer can be provided in a dosing head that is configured to dose the mixed components.

The conveyance of the polyol and isocyanate components from the vessels to the dosing head preferably occurs within conveying tubes that connect the vessels with the dosing head. Furthermore, said conveyance can be done under pressure for instance with the help of pumps, possibly in a closed circuit with the vessels being under pressure. A preferred pressure is between 2 bar to 10 bar.

The polyol component and the isocyanate component can be mixed in a mixer such as a dynamic mixer and preferably at a high rotation speed such as between 500 rpm to 5000 rpm. However, other mixers are likewise conceivable. For instance, the polyol and isocyanate components can be mixed in a static mixer or in a counter-current injection mixer.

The polymer component C1 and the isocyanate component C2 can be applied directly on the substrate or indirectly via at least one liner. That is, once the polyol component and the isocyanate component are mixed so as to form a mixture, said mixture is preferably applied to the substrate. Said application can be a direct application, wherein the mixture is directly applied on the substrate. In this case, it is preferred that a liner is arranged on the mixture once the mixture is applied on the substrate. Alternatively, it is likewise conceivable that the mixture is applied to the liner, and wherein the substrate is then arranged on the liner comprising the mixture. The liner serves the purpose of ensuring a flat and sticky surface of the polyurethane foam after curing. The liner can be siliconized paper, siliconized thin plastic film or any reusable for instance plastic band that is easily removed after curing from the polyurethane foam surface without damaging it.

The application of the mixture can be done via a moving nozzle in order to apply the mixture homogeneously over an entire width of the substrate and/or the liner. However, it is likewise conceivable to apply the mixture with a fixed nozzle, preferably a flat wide nozzle. The application of the mixture via a nozzle can be referred to as a die application process, wherein the nozzle is called a die.

It should be noted that other types of application processes are likewise conceivable. For instance, the mixture can be sprayed onto the substrate, whereby the mixture is homogeneously distributed over the entire width of the substrate and/or the liner as well.

To this end it is preferred that the polymer component C1 and the isocyanate component C2 are applied to the substrate via a commercially available device, for instance a 2KPLI foam gasket application machine or a 2KPLI adhesive application machine.

Moreover, in order to ensure a homogeneous thickness of the adherent layer on the substrate rollers or the like can be used and between which the substrate, the mixture and possibly the liner are passed so that the mixture is evenly distributed.

The polyol component C1 and the isocyanate component C2 are preferably foamed and/or cross-linked and/or cured after being applied to the substrate and preferably through the action of at least one of a gelling catalyst or blowing catalyst and/or by heating.

It is preferred that the polyol component and the isocyanate component, i.e. the mixture, is foamed and/or cross-linked and/or cured after being applied to the substrate. It is particularly preferred that the foaming and/or cross-linking and/or curing occurs after the substrate, the mixture and possibly the liner are passed between the rolls mentioned above.

Moreover, foaming and/or cross-linking and/or curing can occur through the sole action of the gelling catalyst and/or the blowing catalyst or it can be accelerated by the application of heat and at an increased temperature. A preferred temperature is in the range of 30 °C to 80 °C. For instance, the substrate, the mixture and possibly the liner can be placed in and particularly preferably conveyed through an oven.

The substrate and the adherent layer can be winded-up into at least one roll after being cured and/or foamed in at least one step of winding-up. If present, the liner can be removed before or after the winding-up.

That is, once the mixture is cured and/or foamed so as to form the adherent layer it is preferred that the substrate and its adherent layer are winded-up into rolls. The liner, if present, can be removed before or after the substrate and the adherent layer are winded- up into rolls.

Hence, in the step of winding-up the finished material, i.e. the substrate comprising the adherent layer, is winded-up as a roll. In case that a stiff liner such as siliconized paper has been used said liner is preferably removed before generating the rolls since wrinkles in the paper or in the polyurethane foam or the substrate are created otherwise.

The roll can be subjected to edge-trimming and/or cutting and/or die-cutting.

The cutting is preferably carried out with a rotative tool or circular blade so as to form a plate roll. The cutting can also involve cutting spools on a spooling machine. The die-cutting preferably produces spacer pads on rolls with a rotative tool or a flat tool. The die-cutting can also produce pre-cut spacers on rolls with a rotative tool or a flat tool. It is also conceivable that two rolls are put together such that the polyurethane foam of one of the rolls rests against the polyurethane foam of the other roll, and wherein die-cutting is performed so as to cut them into loose pads. The thus produced loose pads of spacers are still arranged in a manner that the polyurethane foam of one of the spacers rests against the polyurethane foam of the other spacer. For use, the spacers can simply be separated by a user, and the separated spacers can be arranged on the articles to be separated as described earlier. That is, once the adherent layer is generated on the substrate it is preferred to produce spacers of a desired end-shape.

The formation of spacers of a desired end-shape can occur before or after removal of the liner, if present.

Spacers of said end-shape are preferably produced by means of a so-called (die-)cutting. For instance, the substrate and its adherent layer that are winded into rolls can be edgetrimmed or can be cut as a plate roll preferably using a rotative tool or a circular blade.

The expression cutting refers to rolls cutting, i.e. cutting a roll that is for instance 180 mm wide into 10 rolls with width 18mm. Other dimensions are of course likewise conceivable. The expression die-cutting refers to cutting small pieces with a tool from a roll materials.

Furthermore, the formation of the spacers of said end-shape can be done with or without a previous step of winding the finished material into rolls. For instance, if the finished material has been winded into rolls, a subsequent die-cutting can be done with the rolls as a starting material.

Furthermore, said plate rolls can be die-cut into small spacer pads on rolls via a rotative tool or a flat tool. A preferred size of said spacer pads on rolls is 18 millimeter x 18 millimeter, although other sizes are likewise conceivable.

Moreover, wider rolls can be directly die-cut with a rotative tool or a flat tool into pre-cut spacers on rolls, wherein said die-cutting can be done in the presence of absence of a liner.

In a further aspect foamed polyurethane is used for producing an adherent layer of a spacer for separating surface of adjacent articles, wherein the spacer comprises at least one substrate being bio-based.

Any statements made herein regarding the spacer or the method of producing the spacer preferably likewise apply to the use of foamed polyurethane for producing the adherent layer of the spacer and vice versa. BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described in the following with reference to the drawings, which are for the purpose of illustrating the present preferred embodiments of the invention and not for the purpose of limiting the same. In the drawings,

Fig. 1 shows a perspective view of a spacer comprising an adherent layer being arranged on a substrate according to the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

Figure 1 depicts a spacer 1 for separating surfaces of adjacent articles (not depicted) according to the invention. The spacer 1 comprises here one adherent layer 2 and one substrate 3. The adherent layer 2 is arranged directly on the substrate 3 and is configured to adhere to a surface of an article.

That is, the adherent layer 2 and the substrate 3 are arranged above one another with respect to an extension direction E of the spacer 1 running from a top side 4 of the spacer 1 to a bottom side 5 of the spacer 1. A top surface 6 of the adherent layer 2 provides the top side 4 of the spacer 1 and a bottom surface 7 of the substrate 3 provides the bottom side 5 of the spacer 1. In use, the top surface 6 of the adherent layer 2 adheres to a surface of a first article and the bottom surface 7 of the substrate 3 rests against a surface of an adjacent second article.

Various end-shapes of the spacer 1 are conceivable and are determined based on the intended end-use of the spacer. As such, the dimensions of the spacer 1 such as a thickness t, width w and height h of the spacer, in particular a thickness ts, ta, a width ws, wa and a height hs, ha of the substrate 3 and of the adherent layer 2, can vary. LIST OF REFERENCE SIGNS spacer ta thickness adherent layer adherent layer w width spacer substrate ws width substrate top side of spacer wa width adherent layer bottom side of spacer h height spacer top surface of adherent layer hs height substrate bottom surface of substrate ha height adherent layer

E extension direction thickness spacer thickness substrate