Hot melt adhesive composition containing a wax of natural origin

Abstract

The present invention relates to a hot-melt adhesive composition comprising: i) a metallocene-catalyzed copolymer; ii) 2% to 50% by weight of a natural wax having a dropping point from 65°C to 105°C, relative to the total weight of said composition; iii) a tackifying resin; said hot-melt adhesive composition having a viscosity of less than 3,000 mPa·s at 130°C. Figure: None

Description

Title of the invention: Hot-melt adhesive composition comprising a wax of natural origin Field of invention

[0001] The present invention relates to a hot melt adhesive composition comprising a wax of natural origin.

[0002] The present invention also relates to the uses of said composition. Technical background

[0003] Hot melt adhesive products are widely used in various commercial applications such as assembly or packaging, including for example the closing of boxes or cases, particularly cardboard.

[0004] Hot melt adhesives are typically applied to a substrate in a molten state. Most hot melt adhesives on the market require temperatures of 170°C or higher to fully melt the components of said adhesives and achieve a satisfactory viscosity for application. However, these high temperatures increase the risks of burns and the inhalation of residual volatile compounds for operators on production lines. In addition, the use of high temperatures requires significant energy consumption.

[0005] Hot-melt adhesives allowing application at lower temperatures (for example less than or equal to 150°C) have been developed recently. However, these hot-melt adhesives do not allow good adhesion to be combined at both low and high temperatures. However, hot-melt adhesives used for packaging such as, for example, the closure of boxes or cases, particularly cardboard, are subjected during their transport and storage to various temperature ranges depending on climatic conditions, geographical areas, etc. Similarly, hot-melt adhesives, to be useful in the field of packaging, must be capable of ensuring good bonding of substrates such as paper, solid cardboard, corrugated cardboard, coated, varnished, laminated, metallized, treated, coated, etc. This good level of bonding results in defibration over a wide temperature range.

[0006] Finally, there are currently few hot melt adhesives made from renewable raw materials. There is a growing desire to reduce the carbon footprint and produce more environmentally friendly products.

[0007] There is therefore a need for new hot-melt adhesives which can at least partially overcome at least one of the aforementioned drawbacks.

[0008] More particularly, there is a need for new hot melt adhesives applicable at low temperatures (for example less than or equal to 150°C) while exhibiting good adhesive properties over a wide temperature range, for example from -20°C to 60°C.

[0009] There is a need for novel hot melt adhesives applicable at low temperatures (e.g., less than or equal to 150°C) having good adhesive properties over a wide temperature range, e.g., from -20°C to 60°C, and good heat resistance (e.g., 50°C or more). Description of the invention

[0010] The present invention relates to a hot-melt adhesive composition comprising:

[0011] i) a copolymer polymerized by metallocene catalysis;

[0012] ii) from 2% to 50% by weight of a wax of natural origin having a dropping point ranging from 65°C to 105°C, relative to the total weight of said composition;

[0013] iii) a tackifying resin having a softening temperature less than or equal to 115°C chosen from:

[0014] a) terpene resins,

[0015] b) partially or totally hydrogenated resins chosen from:

[0016] b-1) rosins of natural origin or partially or totally modified hy drug-containing agents, such as, for example, rosin extracted from pine gum, wood rosin extracted from tree roots and their dimerized, polymerized derivatives;

[0017] b-2) partially or fully hydrogenated rosin esters such as example partially or fully hydrogenated glycerol esters of rosin, partially or fully hydrogenated pentaerythritol esters of rosin;

[0018] b-3) partially or totally hydrogenated aliphatic resins,

[0019] b-4) partially or totally hydrogenated cycloaliphatic resins;

[0020] b-5) aromatic modified aliphatic or cycloaliphatic resins, for example partially or totally hydrogenated,

[0021] c) and mixtures thereof;

[0022] said hot melt adhesive composition having a viscosity of less than 3,000 mPa.s at 130°C. Copolymer i)

[0023] For the purposes of the present invention, the term "copolymer" refers to a polymer formed by polymerization of at least two different monomers. The term "copolymer" also covers terpolymers which contain at least three different types of monomers.

[0024] The copolymer i) polymerized by metallocene catalysis may be a copolymer comprising ethylene, a copolymer comprising propylene, or their mixtures.

[0025] The copolymer i) polymerized by metallocene catalysis can be chosen from:

[0026] -copolymers comprising ethylene and at least one C3-C20-a-olefin;

[0027] - copolymers comprising propylene and at least one monomer chosen from ethylene and C4-C20-a-olefins;

[0028] - their mixtures.

[0029] The blends may be a blend of at least two different copolymers comprising ethylene and at least one C3-C20-a-olefin; a blend of at least two different copolymers comprising propylene and at least one monomer selected from ethylene and C4-C20-a-olefins; a blend of one or more copolymers comprising ethylene and at least one C3-C20-a-olefin with one or more copolymers comprising propylene and at least one monomer selected from ethylene and C4-C20-a-olefins.

[0030] The copolymers comprising ethylene and at least one C3-C20-a-olefin are preferably those comprising ethylene in a majority mass proportion. The term "in a majority mass proportion of ethylene" means that the copolymer comprises a mass content of ethylene greater than the mass content of the other C3-C20-a-olefins.

[0031] The copolymers comprising propylene and at least one monomer chosen from ethylene and C4-C20-a-olefins are preferably those comprising propylene in a majority mass proportion. The term "in a majority mass proportion of propylene" means that the copolymer comprises a mass content of propylene greater than the mass content of the other monomers chosen from ethylene and C4-C20-a-olefins.

[0032] The copolymers comprising propylene and at least one monomer chosen from ethylene and C4-C20-a-olefins are preferably propylene-ethylene copolymers.

[0033] The C3-C20-a-olefins are preferably chosen from C4-C10-a-olefins, and even more preferably chosen from C4-C8-a-olefins.

[0034] The C4-C20-a-olefins are preferably chosen from C4-C10-a-olefins, and even more preferably chosen from C4-C8-a-olefins.

[0035] Preferably, the copolymer i) is chosen from copolymers comprising ethylene and at least one C3-C20-a-olefin.

[0036] The mass content of ethylene in said copolymer i) may range from 50% to 99%, preferably from 50% to 80%, and even more preferably from 50% to 70% by weight relative to the total weight of said copolymer i).

[0037] Although a polymer is often characterized as "made of" such monomers, or "based on" such monomers or "comprising" such monomers, or the like, it goes without saying that we refer to the remainder of said monomers and not to the unpolymerized monomers.

[0038] The aforementioned copolymer i) is obtained by polymerization of monomers in the presence of a metallocene catalytic system. Metallocene catalysis is well known to those skilled in the art. Metallocene catalytic systems may in particular comprise a central transition metal and one or more ligands coordinated to the metal center. Examples of such systems are for example described in US 9,998,469.

[0039] The copolymers can be obtained from monomers that are at least partially bio-sourced or from the circular economy.

[0040] The C3-C20-a-olefins may be linear or branched. They may be selected from the group consisting of propene, butene, pentene, 3-methylbutene, hexene, 3-methylpentene, octene, norbonene, nor-bonadiene, 1-dodecene, 1-hexadodecene, 1-decene, 1-nonene, 1-methylnonene, trimethylheptene, 4-methylpentene, ethylpentene, 3-methylhexene, and mixtures thereof.

[0041] The C4-C20-a-olefins may be linear or branched. They may be selected from the group consisting of butene, pentene, 3-methylbutene, hexene, 3-methylpentene, octene, norbonene, norbonadiene, 1-dodecene, 1-hexadodecene, 1-decene, 1-nonene, 1-methylnonene, trimethylheptene, 4-methylpentene, ethylpentene, 3-methylhexene, and mixtures thereof.

[0042] Preferably, the C3-C20-a-olefins are chosen from propene, hexene, octene and mixtures thereof.

[0043] The mass content of C3-C20-a-olefins in said copolymer i) may be at least 20%, preferably may range from 20% to 49%, even more preferably from 30% to 49%, relative to the total weight of said copolymer i).

[0044] Preferably, the copolymer i) is a copolymer comprising ethylene and octene, even more preferably the copolymer i) is a copolymer comprising only ethylene and octene, and in particular a copolymer comprising only ethylene and from 20% to 49% by weight of octene relative to the total weight of said copolymer.

[0045] The copolymer i) polymerized by metallocene catalysis may or may not be functionalized.

[0046] For the purposes of the present invention, the term “functionalized polymer” means a polymer chemically modified so as to obtain pendant functional groups in the backbone of said polymer. The functional groups may be chosen from epoxies, silanes, amides, carboxylic acids, esters, anhydrides, and their mixtures.

[0047] Preferably, the copolymer i) polymerized by metallocene catalysis is not functionalized.

[0048] The copolymer i) polymerized by metallocene catalysis may have a flow index (or MFI, also called in English "melt flow index") greater than 15 g / 10 min, preferably greater than 400 g / 10 min, and even more preferably between 800 and 1500 g / 10 min.

[0049] The flow index of the copolymer i) is measured at 190°C and for a total weight of 2.16 kg, and is measured in accordance with ASTM D1238.

[0050] The copolymer may have a glass transition temperature (Tg) less than or equal to -35°C. The glass transition temperature may be measured by DSC “Differential Scanning Calorimetry”.

[0051] The copolymer i) may be a block or random copolymer.

[0052] The copolymer i) polymerized by metallocene catalysis may have a density ranging from 0.80 g / cm3 to 0.90 g / cm3, preferably from 0.85 to 0.90 g / cm3. The density of the copolymer i) may be measured according to ASTM D792.

[0053] The copolymers i) polymerized by metallocene catalysis may be commercially available. Examples include Affinity™ marketed by Dow, such as Affinity® GA 1900 (C2 / C8 copolymer) or Affinity® GA 1950 (C2 / C8 copolymer), EXACT™ marketed by ExxonMobil Chemical (C2 copolymers), or Versify™ marketed by Dow Chemicals (C3 copolymers), or Vistamaxx™ marketed by ExxonMobil Chemical (C3 copolymers).

[0054] The hot-melt adhesive composition may comprise from 20% to 60% by weight, preferably from 25% to 50% by weight, and even more preferably from 25% to 45% by total weight of copolymer(s) i), relative to the total weight of said composition. Wax of natural origin ii)

[0055] The hot-melt adhesive composition comprises from 2% to 50% by weight, relative to the total weight of said composition, of a wax of natural origin having a dropping point ranging from 65°C to 105°C.

[0056] The dropping point is known as the “drop melting point” in English.

[0057] The wax preferably has a dropping point ranging from 70°C to 105°C, more preferably temperature from 80°C to 105°C.

[0058] The dropping point of the wax can be measured by the dropping point method according to ASTM DI27.

[0059] The wax of natural origin ii) can be chosen from animal waxes and vegetable waxes, preferably from vegetable waxes.

[0060] Vegetable waxes can be chosen from the group consisting of Camauba, rice bran wax, sugarcane wax, natural hydrogenated soybean, jojoba, castor or palm oil, and mixtures thereof.

[0061] Preferably, the wax of natural origin ii) is a vegetable wax chosen from Camauba wax, rice bran wax, and mixtures thereof.

[0062] Carnauba is an extremely common palm tree in the northeast of Brazil, the wax on the surface of its palms of which has been exploited on a large scale for many years.

[0063] Carnauba wax is typically composed of 80-90% esters combining:

[0064] -aliphatic acids (C24-C28) and alcohols (C30-C34);

[0065] -to the preceding acids and alcohols, [3-hydroxy-acids (C22-C28) and diols (C24-C34);

[0066] -diols (C24-C34) and p-methoxy-cinnamic acid.

[0067] Carnauba wax can be present in several grades (Tl, T3 and T4): Tl being the purest form.

[0068] The naturally occurring wax ii) may have an acid number ranging from 0 to 30 mg KOH / g, preferably from 2 to 15 mg KOH / g. The acid number of the wax may be measured according to ASTM-1386.

[0069] The naturally occurring wax ii) may have a needle penetration value at 25°C ranging from 0 to 20 dmm, preferably from 0 to 15 dmm. The needle penetration value may be measured according to ASTM D1321.

[0070] The adhesive composition preferably comprises from 2% to 50%, preferentially from 4% to 45%, and even more preferentially from 4% to 30% by weight of wax(es) ii) relative to the total weight of said composition.

[0071] Waxes of natural origin are for example Camauba Tl wax (dropping point 82-86°C) marketed by Norevo, Camauba wax marketed by Munzig (dropping point: 81-89°C), Licocare RBW 300 wax (rice bran wax, dropping point = 91-105°C) marketed by Clariant, Deurex wax X52G (cane sugar wax, dropping point =78-82°C) marketed by Deurex. Tackifying resin iii)

[0072] The hot-melt adhesive composition comprises a tackifying resin iii) having a softening temperature of less than or equal to 115°C, said tackifying resin being chosen from the group consisting of:

[0073] a) terpene resins,

[0074] b) partially or totally hydrogenated resins chosen from:

[0075] b-1) rosins of natural origin or partially or totally modified hy drug-containing agents, such as, for example, rosin extracted from pine gum, wood rosin extracted from tree roots and their dimerized derivatives, po- lymerized;

[0076] b-2) partially or fully hydrogenated rosin esters such as example partially or fully hydrogenated glycerol esters of rosin, partially or fully hydrogenated pentaerythritol esters of rosin;

[0077] b-3) partially or totally hydrogenated aliphatic resins,

[0078] b-4) partially or totally hydrogenated cycloaliphatic resins;

[0079] b-5) aromatic modified aliphatic or cycloaliphatic resins, for example partially or totally hydrogenated,

[0080] c) and mixtures thereof.

[0081] The softening temperature (or point) is determined in accordance with the standardized ASTM E28 test, the principle of which is as follows: a brass ring with a diameter of approximately 2 cm is filled with the resin to be tested in the molten state. After cooling to room temperature, the ring and the solid resin are placed horizontally in a glycerin or other thermostatically controlled bath, the temperature of which can vary by 5°C per minute. A steel ball with a diameter of approximately 9.5 mm is centered on the solid resin disc. The softening temperature is - during the phase of heating the bath at a rate of 5°C per minute - the temperature at which the fine resin disc, 25.4 mm high, under the weight of the ball.

[0082] The tackifying resin iii) preferably has a softening temperature ranging from 60°C to 115°C, more preferably from 80°C to 110°C, and even more preferably from 90°C to 110°C.

[0083] The tackifying resin iii) may have a weight-average molar mass Mw generally between 500 Daltons and 1000 Daltons, preferably between 600 Daltons and 900 Daltons.

[0084] The weight-average molecular masses of the tackifying resins can be measured according to methods well known to those skilled in the art, for example by size exclusion chromatography using a polystyrene-type standard.

[0085] The terpene resins a) cover in particular the resins synthesized by (co)-polymerization of one or more terpene monomers such as for example α-pinene, β-pinene, D-Lhnonene; the resins synthesized by copolymerization of one or more terpene monomers with one or more non-terpene monomers, for example chosen from styrene, methylstyrene, isoprene, etc.; the terpene-phenolic resins; and their partially or totally hydrogenated derivatives.

[0086] Resins synthesized by (co)polymerization of one or more terpene monomers are known under the name polyterpenes.

[0087] Terpene-phenolic resins, (or also called terpene-phenols) are typically obtained by polymerization of terpenic hydrocarbons and phenols, in the presence of a Friedel-Crafts catalyst.

[0088] Among the terpene resins, terpene-phenolic resins are preferred.

[0089] Among the terpene resins, we can notably cite Dercolyte® M105 available from the company “Résiniques et Terpéniques or DRT” (which is a polyterpene resin having a softening temperature of 105°C), Dertophene ® T105 marketed by DRT (which is a terpene-phenolic resin having a softening temperature of 105°C), Sylvalite 1105 marketed by Kraton (which is a terpene-phenolic resin having a softening temperature of 105°C), PICCO® AR-85 available from the company EASTMAN (having a softening point of 85°C), “PICCO® AR-100” also available from the company EASTMAN (having a softening point of 100°C).

[0090] Note that these aforementioned resins b) cover all resins possibly modified by an acid or anhydride (such as for example maleic acid or maleic anhydride).

[0091] Partially or totally hydrogenated aliphatic hydrocarbon resins b3) are well known to those skilled in the art. These are resins resulting from the polymerization of mixtures of unsaturated aliphatic hydrocarbons having, for example, 5 carbon atoms (which may, for example, be derived from petroleum or other fractions), followed by a hydrogenation step (total or partial).

[0092] Partially or totally hydrogenated cycloaliphatic hydrocarbon resins b4) are well known to those skilled in the art. These are resins resulting from the polymerization of mixtures of unsaturated cycloaliphatic hydrocarbons having, for example, 10 carbon atoms (which may, for example, be derived from petroleum or other fractions), followed by a hydrogenation step (total or partial). They can in particular be obtained from dicyclopentadiene and their derivatives (methyldicyclopentadiene, dimethyldicyclopentadiene, etc.). Among the cycloaliphatic hydrocarbon resins, DCPD (dicyclopentadiene) resins are particularly preferred.

[0093] The aromatic modified aliphatic or cycloaliphatic hydrocarbon resins can be derived from the copolymerization of aliphatic (for example C5) or cycloaliphatic olefins and aromatic (for example C9) olefins, followed by a hydrogenation step (total or partial), the content of aliphatic or cycloaliphatic olefins being in the majority compared to the aromatic olefins.

[0094] The aforementioned partially or totally hydrogenated resins b) are preferably chosen from the group consisting of cycloaliphatic resins, aromatic modified aliphatic or cycloaliphatic resins, and mixtures thereof.

[0095] Among the resins b-1), we can for example cite the Forai® DX resin (fully hydrogenated rosin resin) from DRT having a higher softening point at 70°C, Forai® AX-E (fully hydrogenated rosin resin) from Eastman having a softening point of 80°C.

[0096] Among the resins b-2), we can for example cite Forai® 3085 (hydrogenated rosin glycerol ester resin) from DRT having a softening point of 80°C, Forai® 85E (hydrogenated rosin glycerol ester resin) from the company Eastman having a softening point of 85°C.

[0097] Among the resins b-3), Eastotac® H100W (hydrogenated C5 resin) from the Eastman company having a softening point of 100°C.

[0098] Among the resins b-4), we can for example cite the Escorez® 5400 resin from the company Exxon Chemicals (hydrogenated DCPD resin) having a softening point of 100°C, the Sukorez® SU 100 (hydrogenated DCPD resin) from Kolon having a softening point of 105°C.

[0099] Among the resins b-5), we can for example cite Sukorez® SU400 (hydrogenated DCPD / C9 resin) marketed by Kolon having a softening point of 100°C.

[0100] Preferably, the tackifying resin iii) is chosen from terpene-phenolic resins and their partially or totally hydrogenated derivatives, partially or totally hydrogenated cycloaliphatic resins, partially or totally hydrogenated aromatic modified aliphatic or cycloaliphatic resins, and mixtures thereof, and even more preferably from terpene-phenolic resins and their partially or totally hydrogenated derivatives, and optionally partially or totally hydrogenated aromatic modified DCPD resins.

[0101] Preferably, the tackifying resin iii) is a bio-sourced tackifying resin.

[0102] In the context of the present invention, the term “bio-tackifying resin” is understood to mean: sourced” a tackifying resin that is derived at least in part from a biomaterial.

[0103] In the context of the invention, the term “bio-carbon” or “bio-sourced carbon” means carbon of renewable origin or of natural origin derived from a biomaterial, as indicated below. The terms “bio-carbon content” and “biomaterial content” are used identically.

[0104] The carbon of biomaterials derives from the photosynthesis of plants and therefore from atmospheric CO2. The degradation (by degradation is also understood combustion / incineration at the end of their life) of these materials into CO2 therefore does not contribute to global warming since there is no increase in carbon emitted into the atmosphere. The CO2 balance of biomaterials is therefore improved and contributes to the reduction of the carbon footprint of the products obtained (only the manufacturing energy is to be taken into consideration). On the contrary, a material of fossil origin which degrades into CO2 contributes to increasing the level of CO2 and therefore to global warming.

[0105] In the context of the invention, the terms “biomaterials” and “bio-sourced materials” are used identically.

[0106] A material of renewable origin, called "biomaterial" is an organic material in which carbon is derived from CO2 recently fixed (on a human scale) by photosynthesis from the atmosphere. On land, this CO2 is captured or fixed by plants. In the ocean, CO2 is captured or fixed by bacteria or plankton carrying out photosynthesis. A biomaterial (100% carbon of natural origin) has a 14C / 12C isotope ratio greater than 10 12 typically approximately 1.2 x 10 12, while a fossil material has a ratio equal to 0. Indeed, the 14C isotope is formed in the atmosphere and then integrated by photosynthesis, over a period of at most a few decades. The half-life of 14C is 5730 years. Thus, materials resulting from photosynthesis, for example plants in general, necessarily have a maximum content in the isotope 14C.

[0107] The biomaterial content or biocarbon content is determined by the standards ASTM D 6866 (ASTM D 6866-06) and ASTM D 7026 (ASTM D 7026-04). The ASTM D 6866 standard is "Determining the biobased content of natural range materials using carbon and isotope ratio mass spectrometry analysis" while the ASTM D 7026 standard is "Sampling and reporting of results for determination of biobased content of materials via carbon isotope analysis". The second standard refers in its first paragraphs to the first standard.

[0108] The first standard describes a test for measuring the 14C / 12C ratio of a sample and comparing it with the 14C / 12C ratio of a reference sample of 100% renewable origin, to give a relative percentage of carbon of renewable origin in the sample.

[0109] Preferably, the tackifying resin iii) has a bio-carbon content greater than or equal to 70%, even more preferably greater than or equal to 80%.

[0110] The hot-melt adhesive composition may comprise from 30% to 60% by weight of tackifying resin(s) iii), preferably from 35% to 55% by weight, and even more preferably from 40% to 55% by weight relative to the total weight of said composition.

[0111] According to a preferred embodiment, the hot-melt adhesive composition does not comprise a tackifying resin chosen from partially or totally hydrogenated aromatic resins. Other waxes iv)

[0112] The hot-melt adhesive composition may further comprise one or more additional wax(es) iv) different from the above-mentioned waxes of natural origin ii).

[0113] The waxes iv) may be chosen from the group consisting of synthetic waxes such as, for example, Fischer-Tropsch waxes, petroleum waxes such as microcrystalline waxes and paraffins, and mixtures thereof.

[0114] The hot-melt adhesive composition may comprise a total content of additional wax(es) iv) ranging from 0% to 25%, preferably from 0% to 15%, relative to the total weight of said composition.

[0115] Preferably, the hot-melt adhesive composition comprises less than 5% by weight of polyethylene wax (PE wax), preferably less than 3% by weight, even more preferably less than 1% by weight, and even more advantageously less than 0.1% by weight relative to the total weight of said composition. According to an even more preferred embodiment, the composition comprises less than 0.05% by weight of polyethylene wax, and even more preferably said adhesive composition does not comprise polyethylene wax. Additional compounds

[0116] The hot-melt adhesive composition may also include one or more additives appropriately chosen so as not to deteriorate the properties of the adhesive. Examples include plasticizers, oils, antioxidants, anti-caking agents, pigments, fluorescent agents (IR or UV), IR or UV absorbers, flame retardants, dyes, fillers, and mixtures thereof. These additives may be chosen from those usually used in adhesive compositions.

[0117] The total content of additional compound(s) may range from 0% to 10%, preferably from 0% to 5% by weight relative to the total weight of said composition.

[0118] Preferably, the hot melt adhesive composition does not comprise ethyl-vinyl acetate (EVA) copolymer. Adhesive composition

[0119] The hot-melt adhesive composition has a viscosity of less than 3000 mPa.s at 130°C, preferably between 500 mPa.s and 2500 mPa.s, and even more preferably between 1000 mPa.s and 2500 mPa.s.

[0120] Viscosity is measured by Brookfield viscosity according to ASTM method D3236. This viscosity can be measured using a Brookfield Thermosel apparatus or any other suitable viscometer, and using the test techniques as described in this ASTM method.

[0121] The hot-melt adhesive composition may comprise a total biomaterial content greater than or equal to 2%, preferably greater than or equal to 9%, and even more preferably greater than or equal to 45% relative to the total weight of said composition. The biomaterial content is calculated as explained above for the tackifying resin.

[0122] The hot-melt adhesive composition according to the invention can be prepared by simple

[0123] mixture of its components at a temperature between 100°C and 250°C, of preferably from 140°C to 200°C, until a homogeneous mixture is obtained. The required mixing techniques are well known to those skilled in the art.

[0124] The hot melt adhesive composition may have a softening point ranging from 70°C to 115°C, preferably from 75°C to 105°C. The softening point is measured according to the method described for the tackifying resin previously.

[0125] The hot-melt adhesive composition advantageously has a viscosity suitable for application at low temperatures (less than or equal to 150°C, for example 130°C or 150°C).

[0126] The hot melt adhesive composition advantageously further exhibits good adhesive properties over a wide temperature range, for example from -20°C to 60°C. The adhesive properties are advantageously good at low temperatures (for example -20°C) and at high temperatures (for example at 60°C), compared to hot melt adhesive compositions on the market.

[0127] The hot-melt adhesive composition also advantageously has good heat resistance (for example at 50°C or more), namely good cohesion at these temperatures.

[0128] The hot-melt adhesive composition according to the invention is advantageously partly bio-sourced, through the use of wax of natural origin, which responds to the growing interest of the industry for this type of composition intended to reduce dependence on petroleum-based raw materials, while limiting the carbon footprint of manufacturing operations. Uses

[0129] The hot melt adhesive composition of the invention can be used for a wide variety of applications, for example: packaging, paper and cardboard converting, bookbinding, bag making and closing, nonwoven markets, and others. This type of adhesive is particularly used for the formation of boxes, crates, cartons and trays, and as a sealing adhesive, including heat sealing applications.

[0130] The present invention relates to the use of the hot-melt adhesive composition as defined above for bonding two substrates.

[0131] The present invention relates to a method of assembling two substrates by gluing, comprising:

[0132] - a first step of heating the hot-melt adhesive composition such as defined above, for example at a temperature ranging from 90°C to 160°C,

[0133] - a coating step on at least one of the two substrates to be assembled of the com position obtained in the previous step; then

[0134] - the effective contacting of the two substrates so as to prepare an adhesive joint between the two substrates.

[0135] The substrates may be of the same or different nature.

[0136] The substrates can in particular be chosen from virgin or recycled paper, virgin or recycled kraft, high or low density kraft, all types of cardboard and cellulosic substrates, composite materials, fiberboard or particleboard, nonwovens. All these substrates can be treated, coated or coated. The aforementioned composite materials can include papers, krafts or cardboards laminated to metallized or non-metallized films, such as polyethylene, polypropylene, polyethylene terephthalate, Mylar, polyvinylidene chloride, ethylene vinyl acetate and various other types of films, for example, cellulosic-based, or others.

[0137] The above-mentioned substrates are by no means an exhaustive list, as a very wide variety of substrates, including composite materials, find use in the packaging industry.

[0138] The first heating step is notably carried out for a sufficiently long time to make the hot-melt adhesive composition sufficiently liquid to be applied to a substrate.

[0139] In "on-demand" application systems, called tankless systems, hot melt adhesive compositions are fed in the solid state (e.g., as granules), into a heated tank in which the composition is melted, and rapidly applied to a substrate.

[0140] The coating step can be carried out by any methods known to those skilled in the art, such as by injection, by roller, by fiberization or spraying.

[0141] The hot melt adhesive composition may be applied to a substrate in any shape such as, for example, continuous or discontinuous beads, dots, spirals, etc.

[0142] The hot-melt adhesive composition according to the invention can be used for bonding two different or different substrates, for example for making or closing packaging, boxes, cartons, cases, bags, mounting trays or trays, articles which include accessories (for example straws attached to drinks), packaging in reams, cigarettes, filters, book binding.

[0143] All the embodiments described above may be combined with each other. In particular, the various aforementioned constituents of the composition, and in particular the preferred embodiments of the composition, may be combined with each other.

[0144] In the context of the invention, by "between x and y", or "ranging from x to y", is meant an interval in which the limits x and y are included. For example, the range "between 0% and 25%" includes in particular the values ​​0% and 25%.

[0145] The invention is now described in the following exemplary embodiments which are given for purely illustrative purposes, and cannot be interpreted to limit their scope.

[0146] Examples:

[0147] The following ingredients were used:

[0148] [Tableauxl] Raw material Nature Supplier Affinity® GA 1900 Ethylene-Octene Copolymer Dow Primeva® P28800 EVA Repsol Dertophene® T105 Phenolic Terpene Resin DRT Sukorez® SU400 DCPD Modified C9 -Hydrogenated Kolon Dertoline® PLS Rosin Ester Resin Non-Hydrogenated DRT Regalite SI 100 Hydrogenated C9 Aromatic Resin Eastman Sasolwax® H1 Fischer Tropsch Wax Sasol Shell GTL Sarawax® SX80 Fischer Tropsch Shell Wax (Distributor Evonik) Indopol H100 Polybutene Inéos Carnauba Tl Vegetable Wax Norevo Paraffin 64-70 Paraffin Baker Pertrolite Irganox 1010 Antioxidant BASF

[0149] Example 1: preparation of the compositions

[0150] Hot melt adhesive compositions are obtained by hot mixing the ingredients using a Heidolph rod stirrer and a laboratory pot heater. The melting and mixing temperature is generally between 90 and 150°C.

[0151] The compositions prepared are gathered in the following table 1. Example 2: Performance

[0152] The evaluation of the hot melt adhesive is carried out on a 200 g / m2 Kraft liner based on virgin paper fibers (Fipago), which is not treated with any type of primer or varnish.

[0153] Reference cardboard substrates are cut into 5 cm x 10 cm for PAFT (temperature resistance) test, 5 cm x 6 cm for adhesion performance. For For each product, 5 assemblies are prepared and tested.

[0154] For performance evaluation, the adhesive is applied with automatic equipment:

[0155] The adhesive is melted in a melting tank, then applied at 130°C in a bead equivalent to 2g / linear meter on the substrate with an automatic dispensing gun. The adhesive is applied across the width of the substrate in a 4 mm bead equivalent to 2g / linear meter. The second substrate is applied, opposite face, after 1 second of open time, and then pressed for 2 seconds by the machine.

[0156] The physical properties of the adhesives and their performances were measured by the following methods: Viscosity measurement method:

[0157] Viscosity is determined using a Brookfield viscometer, a Brookfield Thermosel heated sample chamber and a needle matched to the expected viscosity. Results are reported in mPa-s. Method of measuring softening point:

[0158] The softening point is determined using an RB65G analyzer according to the so-called Ring-Ball method in accordance with the standard ASTM E28 test. The ring-and-ball method consists of determining the temperature at which a disc of the material held in a ring and loaded with a ball flows over a defined distance when heated at a prescribed rate in a beaker of glycerin or the like. The results are expressed in °C.

[0159] Evaluation of heat resistance - “PAFT” test method:

[0160] The peel adhesion failure temperature (or heat resistance test) is determined as follows:

[0161] The adhesive is applied at 130°C with automatic equipment at 2g / mL on a reference substrate (cut 5 cm x 10 cm) as explained previously.

[0162] After 24 hours, all the assemblies are placed in an oven at the initial temperature of 30°C, the upper substrates of the assemblies are held by a metal structure in the oven and a hole is made on the lower substrates in order to place a weight of 100g.

[0163] The oven temperature is then increased by 5°C / 30 min until the adhesive seal breaks and the weight falls onto the detection cell. The temperature resistance value corresponds to the average value of the temperatures at which the weights fall, for all assemblies (5 assemblies tested per product).

[0164] Adhesion performance - Method for evaluating support defibration:

[0165] The percentage of defibration of the support is the percentage of fiber that covers the area of ​​the adhesive after 2 substrates, which have been previously bonded together by the adhesive, are separated by force. The percentage of fiber defibration exhibited by an adhesive composition is determined as follows:

[0166] All the bonding assemblies are prepared (with an automatic device -5cmx6cm), placed for 24 hours at room temperature, then stored for 3 days inside climatic chambers at -20°C, 5°C, 23°C, and 60°C (5 samples / temperature / adhesive).

[0167] After 3 days, the assemblies are separated from each other at the conditioning temperature by manually pulling on the 2 substrates.

[0168] The surface of the adhesive composition is observed and the percentage of the surface of the adhesive composition that is covered with fibers is determined and recorded in units of % fiber tear according to the following scale:

[0169] [Tables2] % of defibration of the support value 81-100% 5 51-80% 4 21-50% 3 1-20% 2 0% 1

[0170] Compositions having a % of defibration having a value of 5 are sought.

[0171] The results obtained according to the methods described above are presented in the table below:

[0172] Table 1: Performance of the compositions

[0173] [Tables3] comparative 1 Exl Ex 2 Ex 3 Ex 4 comparative 2 comparative 3 comparative 4 Affinity GA 1900 30 35 34 34 34 34 34 Primeva P28800 35 Dertophene T105 45 48 48 45 Sukorez SU400 44 48 Dertoline PLS 48 Regalite S1100 48 Sasolwax H1 5 Sarawax SX 80 7 7 7 7 Carnauba Tl 19 10 10 10 10 19 10 Paraffin 64-70 15 7 Elwax LP1020P Indopol H100 5 Irganox 1010 1 1 1 1 1 1 1 1 Total 100 100 100 100 100 100 100 100 Viscosity mPa 920 2020 1830 2120 1900 7500 2520 1680 @130°C .s Softening point semen t- B&A °C 90 83 81 82 79 86 85 86 Temperature resistance Adhesive applied at 130°C °C 35 55 54 58 55 52 54 Adhesion performance s Adhesive applied at 130°C Fibre loss of the substrate (%) -20° C 3 4 4 4 4 - 1 2 5°C 5 5 5 5 5 - 2 4 23° C 5 5 5 5 5 - 5 5 50° C 4 5 5 5 5 - 5 5 60° C 1 5 5 5 5 - 5 5

[0174] Comparative Example 1 is a market adhesive. The combination of the different raw materials allows application at low temperatures but does not allow a good level of performance to be achieved at very low temperatures (-20°C), and the bonding performance at high temperatures is limited by the low temperature resistance (PAFT).

[0175] The compositions of Examples 1 to 4 advantageously have a good level of heat resistance (PAFT) > 50°C while maintaining very good adhesive performance over a wide temperature range: from -20°C to 60°C (defibration between 4 and 5 according to the indicative table). The viscosity level also allows them to be applied from 130°C and above, while maintaining good wettability of the support.

[0176] Comparative example 2, which comprises a non-hydrogenated rosin ester resin, does not allow an acceptable viscosity level to be achieved for application at 130°C. It was not possible to make the bonds with this comparative composition, which is not compatible.

[0177] Comparative Example 3 uses an EVA copolymer, not a me- tallocene. This composition has poor bonding performance at low temperatures (fiber removal 1 and 2 in value according to the reference table).

[0178] Comparative Example 4 does not use a tackifying resin as defined in the invention. This example uses a hydrogenated C9 aromatic tackifying resin. This composition leads to poor performance at low temperature (defibration 2 in value according to the reference table at -20°C). At 5°C, the defibration values ​​are lower than those obtained with the compositions of Examples 1 to 4 using a composition according to the invention.

Claims

Claims

1. Hot-melt adhesive composition comprising: i) a copolymer polymerized by metallocene catalysis; ii) from 2% to 50% by weight of a wax of natural origin having a dropping point ranging from 65°C to 105°C, relative to the total weight of said composition; iii) a tackifying resin having a softening temperature less than or equal to 115°C chosen from: a) terpene resins, b) partially or totally hydrogenated resins chosen from: b-1) rosins of natural origin or partially or totally hydrogenated modified rosins, such as for example rosin extracted from pine gum, wood rosin extracted from the roots of the tree and their dimerized, polymerized derivatives; b-2) partially or fully hydrogenated rosin esters such as, for example, partially or fully hydrogenated glycerol rosin esters, partially or fully hydrogenated pentaerythritol rosin esters;b-3) partially or fully hydrogenated aliphatic resins, b-4) partially or fully hydrogenated cycloaliphatic resins; b-5) partially or fully hydrogenated aromatic modified aliphatic or cycloaliphatic resins, c) and mixtures thereof; said hot melt adhesive composition having a viscosity of less than 3,000 mPa.s at 130°C.;

2. Composition according to claim 1, characterized in that the copolymer i) polymerized by metallocene catalysis is chosen from: - copolymers comprising ethylene and at least one C3-C20-a-olefin; - copolymers comprising propylene and at least one monomer chosen from ethylene and C4-C20-a-olefins; - mixtures thereof.

3. Composition according to claim 1 or claim 2, characterized in that the copolymer i) is chosen from copolymers comprising ethylene and at least one C3-C20-a-olefin, preferably chosen from the group consisting of propene, butene, pentene, 3-methylbutene, hexene, 3-methylpentene, octene, norbonene, norbonadiene, 1-dodecene, 1-hexadodecene, 1-decene, 1-nonene, 1-methylnonene, trimethylheptene, 4-methylpentene, ethylpentene, 3-methylhexene, and mixtures thereof.

4. Composition according to any one of claims 1 to 3, characterized in that the copolymer i) is a copolymer comprising ethylene and octene, even more preferably the copolymer i) is a copolymer comprising only ethylene and octene, and in particular a copolymer comprising only ethylene and from 20% to 49% by weight of octene relative to the total weight of said copolymer.

5. Composition according to any one of claims 1 to 4, characterized in that the wax of natural origin ii) has a dropping point ranging from 70°C to 105°C, preferably from 80°C to 105°C.

6. Composition according to any one of claims 1 to 5, characterized in that the wax of natural origin ii) is chosen from vegetable waxes, and preferably from the group consisting of Camauba wax, rice bran wax, sugar cane wax, natural hydrogenated soybean, jojoba, castor or palm oil, and mixtures thereof.

7. Composition according to any one of claims 1 to 6, characterized in that it comprises from 4% to 45%, preferably from 4% to 30% by weight of wax(es) ii) relative to the total weight of said composition.

8. Composition according to any one of claims 1 to 7, characterized in that the tackifying resin iii) is chosen from terpene-phenolic resins and their partially or totally hydrogenated derivatives, partially or totally hydrogenated cycloaliphatic resins, partially or totally hydrogenated aromatic modified aliphatic or cycloaliphatic resins, and mixtures thereof, and even more preferably from terpene-phenolic resins and their partially or totally hydrogenated derivatives, optionally partially or totally hydrogenated aromatic modified DCPD resins.

9. Composition according to any one of claims 1 to 8, characterized in that it comprises from 30% to 60% by weight of tackifying resin(s) iii), preferably from 35% to 55% by weight, and even more preferably from 40% to 55% by weight relative to the total weight of said composition.

10. Composition according to any one of claims 1 to 9, characterized in that it has a viscosity of less than 3000 mPa.s at 130°C, preferably between 500 mPa.s and 2500 mPa.s, and even more preferably between 1000 mPa.s and 2500 mPa.s.

11. Composition according to any one of claims 1 to 10, characterized in that it comprises a total biomaterial content greater than or equal to 2%, preferably greater than or equal to 9%, and even more preferably greater than or equal to 45% relative to the total weight of said composition.

12. Composition according to any one of claims 1 to 11, characterized in that it comprises less than 5% by weight of polyethylene wax, preferably less than 3% by weight, more preferably less than 1% by weight, and even more advantageously less than 0.1% by weight relative to the total weight of said composition.

13. Composition according to any one of claims 1 to 12, characterized in that it does not comprise a partially or totally hydrogenated C9 aromatic tackifying resin.

14. Use of a composition according to any one of claims 1 to 13, for bonding two different or non-different substrates, for example for making or closing packaging, boxes, cartons, cases, bags, mounting trays or trays, articles which include accessories (for example straws attached to drinks), ream packaging, cigarettes, filters, book binding.