WO2022106698A1

WO2022106698A1 - Method for additive manufacturing of intumescent products

Info

Publication number: WO2022106698A1
Application number: PCT/EP2021/082543
Authority: WO
Inventors: Michael Raab
Original assignee: Etex Building Performance Gmbh
Priority date: 2020-11-20
Filing date: 2021-11-22
Publication date: 2022-05-27
Also published as: EP4267375A1

Abstract

The invention relates to a method for additive manufacturing of three-dimensional intumescent products (IP) comprising the steps of: Step 1: providing at least one intumescent composition (C), preferably in the form of a monofilament; Step 2: melting said composition (C) and printing the composition (C) in molten form using an additive manufacturing machine or 3D printer, preferably by using a monofilament additive manufacturing technique, to form the intumescent product (IP); wherein the intumescent composition (C), relative to the total weight of the composition (C), comprises: 20-80 % by weight (wt.%) of at least one binder polymer (P); 2-80 wt.% of at least one intumescent additive (I); 0-78 wt.% of at least one filler (F); wherein the sum of the components of composition (C), excluding the at least one binder polymer (P), is equal to or less than 80 wt.%.

Description

METHOD FOR ADDITIVE MANUFACTURING OF INTUMESCENT PRODUCTS

FIELD OF INVENTION

The present invention relates to a method for additive manufacturing of a three-dimensional intumescent product. The present invention further relates to an intumescent composition for use in additive manufacturing and the use thereof.

BACKGROUND OF THE INVENTION

Additive manufacturing (AM), more commonly known as 3D printing, is radically changing the way in which products are made. This new approach is compatible with a large variety of materials, from metals to living cells, and has a wide range of potential industrial applications AM makes three-dimensional (3D) solid objects of virtually any shape from a digital model. Generally, this is achieved by creating a digital blueprint of a desired solid object with computer-aided design (CAD) modeling software and then slicing that virtual blueprint into very small digital cross-sections. These cross-sections are formed or deposited as thin layers of material one on top of another until a complete three-dimensional object is formed. AM has many advantages, including dramatically reducing the time from design to prototyping to commercial product. Running design changes are possible which also allows for the mass-customization of 3D printed objects (AM objects). Multiple parts can be built in a single assembly. No tooling is required. Minimal energy is needed to make these 3D solid objects. It also decreases the amount waste and raw materials. AM also facilitates production of extremely complex geometrical parts. AM also reduces the parts inventory for a business since parts can be quickly made on-demand and on-site.

However, there is still a need for making AM intumescent products. Intumescent products mainly find their application as fire-stop materials, for example fire penetration seals and cavity firestops. Known intumescent firestop or penetration-sealing products include sealants and mastics; intumescent pipe bands, collars and wraps; intumescent blocks, grills and strips; intumescent fire pillows; intumescent expansion joints; intumescent cavity and lap-jointing seals; intumescent paints and coatings; lightweight cavity barriers; and door strips which comprise intumescent material. These products are incorporated into buildings, automobiles, aircrafts, ships and boats at various stages and places in their construction or refitting. They all have the property of intumescing or expanding when subjected to heat, such as the heat of a fire. Thereby the intumescent products close the passageway through which the fire, flame and/or smoke would otherwise spread. Intumescent products protect the elements of a building from structural collapse and may also allow a means of escape according to prescribed requirements in the relevant country.

In most countries, intumescent products and their applications have to comply with very stringent fire protection standards and regulations. All products need to undergo extensive fire testing to obtain certifications for use of that product in certain applications. In practice, a lot of different prototypes are often required to test different compositions and different product designs to be able to find the right solution for each particular application.

Currently, intumescent products or prototypes are often produced by an injection molding process. However, every product that is produced through injection molding requires a separate mold. Tooling design is one of the most expensive and time-consuming parts of the injection molding process.

As said before, AM on the other hand is much more flexible and allows to create new designs very easily which are brought to life in a matter of hours, hence allowing very rapid and cheap prototyping. Furthermore, AM intumescent products could be mass-customized and can be quickly made on-demand and even on-site. It is therefore desirable to enable the additive manufacturing of intumescent products. However, such intumescent products are intended to expand, when temperature increases due to fire or the like, and therewith to close apertures through which a fire could be transmitted from one space to an adjacent one. It is due to this fire protection purpose, that stringent standards and regulations are applicable. Hence, the additive manufacturing process, which is usually a printing process and typically occurs at higher temperatures using a liquid carrier should not affect the intumescent properties negatively.

Accordingly, there is a further need to provide a method for additive manufacturing products or prototypes that exhibit intumescent properties while maintaining the same or a better quality compared to injection molded intumescent products. Furthermore, there is a need for a flexible, economical and practical method for the additive manufacturing of said three-dimensional intumescent products. SUMMARY OF THE INVENTION

The Applicant has now found a composition and method for additive manufacturing of a three-dimensional product having intumescent properties which fulfils the above-mentioned needs.

Thus, according to a first aspect of the present invention an intumescent composition (C) for use in additive manufacturing method is provided, comprising 20-80 % by weight (wt.%) of at least one binder polymer (P); 20-80 wt.% of intumescent additive (I), comprising expandable graphite; 0-78 wt.% of at least one filler (F); wherein the sum of the components of composition (C), excluding the at least one binder polymer (P), is equal to or less than 80 wt.%.

According to a second aspect of the invention, a method for additive manufacturing of three-dimensional intumescent products (IP) is provided, comprising:

Step 1 : providing at least one intumescent composition (C), preferably in the form of a monofilament;

Step 2: melting said composition (C) and printing the composition (C) in molten form using an additive manufacturing machine or 3D printer, preferably by using a monofilament additive manufacturing technique, to form the intumescent product (IP); wherein the intumescent composition (C), relative to the total weight of the composition (C), comprises:

20-80 % by weight (wt.%) of at least one binder polymer (P);

20-80 wt.% of intumescent additive (I) comprising expandable graphite;

0-78 wt.% of at least one filler (F);

- wherein the sum of the components of composition (C), excluding the at least one binder polymer (P), is equal to or less than 80 wt.%.

According to a third aspect, the invention relates to an additive manufactured three-dimensional intumescent product (IP) obtainable by said additive manufacturing method.

According to further aspects, an additive manufacturing machine (AMM) or 3D printer for use in said additive manufacturing method, and computer instructions which cause an additive manufacturing machine or 3D printer to manufacture said three-dimensional intumescent product (IP), are provided.

Particularly useful compositions included 20-45wt% of expandable graphite, and preferably 25-40wt% expandable graphite. It is more preferably that the composition comprises a further intumescent additive, such as a phosphate compound and/or an amino-compound, for instance an amino- or ammoniumphosphate compound. The total sum of components excluding the binder polymer is more preferably at most 70wt%, by further preference at most 60wt%. This total sum is moreover suitably at least 25wt%, more preferably at least 30wt%, at least 35wt% or even at least 40wt%. It is observed that the intumescent composition of the invention, with at least 20wt% and preferably at least 25wt% expandable graphite behaves distinct from any flame retardant use of graphite, in which the graphite is typically present in an amount of a few percent.

DETAILED DESCRIPTION OF THE INVENTION

Within the context of the present invention, the expression “at least one” is intended to denote one or more than one. Mixtures can also be used for the purpose of the invention.

In the remainder of the text, the expressions “Intumescent composition (C)” "Binder polymer (P)", “Intumescent additive (I)” and “filler (F)” are understood, for the purposes of the present invention, both in the plural and the singular form.

The term "intumescent composition", “intumescent product” or “intumescent additive”, as used herein, means a composition, product or additive that is able to expand, or swell, when exposed to heat.

The term "monofilament additive manufacturing technique" as used in the present specification and claims means that the product of manufacture can be made by any additive manufacturing technique that makes a three-dimensional solid object of any shape by laying down material in layers from a plastic monofilament from a digital model. For example, the monofilament can be made by laying down a plastic filament that is unwound from a coil or is deposited from an extrusion head. These monofilament additive manufacturing techniques include fused deposition modelling (FDM) and fused filament fabrication (FFF).

The terms "Fused Deposition Modelling (FDM)" or "Fused Filament Fabrication (FFF)" involves building a part or article layer-by-layer by heating thermoplastic material to a semi-liquid state and extruding it according to computer-controlled paths. FDM utilizes a modelling material and a support material. The modelling material comprises the finished piece, and the support material comprises scaffolding that can be mechanically removed, washed away or dissolved when the process is complete. The process involves depositing material to complete each layer before the base moves down the Z-axis and the next layer begins.

The term “expandable graphite” is known per se in the art as a flame retardant intumescent additive, and refers to a mixture of graphite and any type of acid, that is configured for expansion above a predefined temperature. The carbon content hereof is typically in the range of 85-99wt%. The material is typically obtained by treatment of graphite flakes in a bath of an acid and oxidizing agent, such as hydrogen peroxide, potassium permanganate. The acid is preferably a strong acid, such as sulphuric acid or nitric acid, or even a Lewis acid. Most preferably, an expandable graphite is chosen that has a starting temperature of its expansion above the melting temperature of the binder polymer. Such expandable graphites may for instance be so-called expandable graphite intercalation compounds, wherein the compounds comprise as intercalation components at least one Lewis acid, such as a metal halide, for instance AICI3, SbCI5, ZnCI2, YCI3, CrCI3, NiCI2 and/or FeCI3. An organic compound may additionally be intercalated into the graphite, such as known from US2003/ 157015A1, which is included herein by reference.

BINDER POLYMER (P)

Thus, in step 1 of the method of the present invention use is made of at least one intumescent composition (C) comprising from 20 to 80 wt.% of at least one binder polymer (P).

Typical binder polymers (P) suitable for use in the intumescent composition (C) in the method of the present invention may include, but are not limited to, polyolefins, such as polyethylene (PE) having a low density (LDPE) to high density (HDPE), polypropylene (PP), polyethylene-polypropylene copolymers, poly-l- butene, poly(methyl-pentene), copolymers of ethylene and octene, ethylene/propylene-diene terpolymers (EPDM); polylactic acid (PLA), polycaprolactone (PCL), acrylonitrile butadiene styrene (ABS), polyethylene terephthalate (PET), polyethylene trimethylene terephthalate (PETT), polyvinyl alchohol (PVA), polyamide (PA) or nylon, ethylene-vinyl acetate (EVA) copolymers, ethylene-butyl acrylate copolymers (EBA), polyvinyl chloride (PVC), acrylic polymers or copolymers, metallocene polymers, polyphthalamide (PPA), polystyrene (PS), high impact polystyrene (HIPS), silicone rubbers or polymers, latexes, styrene-ethylene-butylene-styrene (SEBS) or other thermoplastic elastomers (TPE), polycarbonate (PC), polyimides, polyetherimide (PEI), polyethersulfone (PES), polysulfone (PSU), polyphenylene oxide (PPO), polyphenylene ether (PPE), polyphenylene ether sulfone (PPSLI), styreneacrylonitrile (SAN), or silicone polycarbonate copolymers, or a mixture of two or more thereof.

Preferably, the binder polymer (P) may be chosen among the group of polyolefins such as low-density polyethylene (LDPE) or high-density polyethylene (HDPE), polypropylene, ethylene-vinyl acetate (EVA) copolymers, ethylene-butyl acrylate (EBA) copolymers, styrene-ethylene-butylene-styrene (SEBS) or other thermoplastic elastomers (TPE), or mixtures of two or more thereof. More preferably, the binder polymer (P) may be selected from polyethylene, in particular low-density polyethylene (LDPE), ethylene-vinyl acetate (EVA) copolymers, ethylene-butyl acrylate (EBA) copolymers or mixtures thereof. Most preferably, the binder polymer (P) is polyethylene, in particular low-density polyethylene (LDPE). A polyolefin or vinylic polymer is polymer obtained by free radical polymerisation. This type of polymers is preferred over condensation polymers, such as polyamides and polyesters, It was observed in preliminary experiments that at least some condensation polymers are sensitive to degradation after melting. The inventor believes that this is due to an interaction between the binder polymer and intumescent additive, such as any acid compound intercalated within the expandable graphite and/or any ammonium or amino compound present as further intumescent additive.

More preferably, said binder polymer is characterized by a melting temperature of below 220°C, for instance below 200°C or even below 180°C. Furthermore, it is deemed beneficial that the melting temperature is at least 100°C, such as at least 120°C. The melting point can be found in databases, such as in Crow’s polymer database. It is not excluded, while referring to a melting point, that a binder polymer of the composition may be in amorphous state or may be semicrystalline. With such a binder polymer, the composition may be sufficiently flowable for additive manufacturing without resulting in premature expansion of the expandable graphite. However, a too low melting temperature gives rise to faster softening, leading to reduced fire protection. Hence, it is deemed advantageou that the melting temperature is even above 120°C, or even 140°C or higher.

Non limitative examples of commercially available low-density polyethylene suitable for use as binder polymer (P) in the intumescent composition (C) in step 1 of the method of the present invention include: Alcudia® available from Repsol, in particular Alcudia® PE 063 (MFR 2,4 g/10 min. at 190°C/2.16 kg, ISO 1133); and LDPE LD 252 available from ExxonMobil™ (MFR 3,8 g/10 min. at 190°C/2.16 kg, ASTM D1238).

Preferably, the melt mass-flow rate (MFR) at 210°C/2.16 kg of said binder polymer (P), is equal to or less than 30 g/10 min., preferably equal to or less than 20 g/10 min., more preferably equal to or less than 15 g/10 min., even more preferably equal to or less than 10 g/10 min.. It is further understood that the lower value of the melt flow rate (MFR) of the binder polymer (P), is not particularly limited but advantageously equal to or greater than 1 g/10 min., preferably equal to or greater than 1.5 g/10 min., more preferably equal to or greater than 2 g/10 min..

The applicants prefer to use ASTM D1238 or ISO 1133 to determine the melt flow rate (MFR).

In a preferred embodiment of the method of the present invention, the weight percent of the binder polymer (P) as used in the intumescent composition (C) in step 1 , relative to the total weight of the composition (C), is advantageously equal to or greater than 22.5 wt.%, preferably equal to or greater than 25.0 wt.%, more preferably equal to or greater than 27.5 wt.% and most preferably equal to or greater than 30.0 wt.%.

It is further understood that, the weight percent of the binder polymer (P), relative to the total weight of the intumescent composition (C), is advantageously equal to or less than 75.0 wt.%, preferably equal to or less than 70.0 wt.%, more preferably equal to or less than 65.0 wt.%, even more preferably equal to or less than 60.0 wt.%, most preferably equal to or less than 55.0 wt.%.

Good results, especially regarding the mechanical stability of the composition (C), were obtained when the weight percent of the binder polymer (P), relative to the total weight of the intumescent composition (C), was between 30.0 and 55.0 wt.%. INTUMESCENT ADDITIVES (l)

In step 1 of the method of the present invention use is made of at least one intumescent composition (C) comprising 2-80 wt% of intumescent additive (I), comprising expandable graphite.

Non limitative examples of commercially available expandable graphite suitable for use as intumescent additive (I) in the intumescent composition (C) in step 1 of the method of the present invention include S7, S500, S7 100, S90 available from Grafitbergbau Kaisersberg GmbH, ES 350 F5, ES700 F5 PH, ES 250 B5, ES 250 B5E available from Kropfmuhl AG, 3772, 3721 , 3335 available from Asbury Carbons.

The inventors have found that the particle size of the intumescent additive (I) influences the distribution of the additive within the intumescent composition (C). By using an intumescent additive (I) having a finer particle size, the distribution is improved and in turn the intumescent behavior, such as the expansion, is positively influenced. Preferably, the particle size is in the range of 0.20-0.60 mm, more preferably 0.3-0.5 mm, as defined by sieving.

The composition may further contain one or more additional intumescent additives. Typical further intumescent additives (I) suitable for use in the intumescent composition (C) in the method of the present invention may include, but are not limited to, ammonium or amino compounds, such as, for example, ammonium poly-phosphate, ammonium dihydrogen phosphate, ethylene-diamine phosphate, ammonium pentaborate, melamine, dicyandiamide, full phosphoric esters with polyols, dipentaerythritol, pentaerythritol, sugar, dextran, starch, vermicular graphite, exfoliating graphite, waterglass or sodium silicates, expanded mica, vermiculite, perlite, or mixtures of two or more thereof.

Preferably, the intumescent additive (I) may be chosen among the group of ammonium polyphosphate, ethylene-diamine phosphate, melamine, dipentaerythritol, pentaerythritol, waterglass or sodium silicates, or mixtures of two or more thereof. More preferably, the intumescent additive (I) may be selected from ammonium polyphosphate, melamine, pentaerythritol, or mixtures thereof.

In a preferred embodiment of the method of the present invention, the weight percent of the intumescent additive (I) as used in the intumescent composition (C) in step 1 , relative to the total weight of the composition (C), is advantageously equal to or greater than 5 wt.%, preferably equal to or greater than 10 wt.%, more preferably equal to or greater than 15 wt.%, even more preferably equal to or greater than 20 wt.%, most preferably equal to or greater than 25 wt.%.

It is further understood that, the weight percent of the intumescent additive (I), relative to the total weight of the composition (C), is advantageously equal to or less than 70 wt.%, preferably equal to or less than 60 wt.%, more preferably equal to or less than 50 wt.%, even more preferably equal to or less than 45 wt.%, most preferably equal to or less than 40 wt.%.

Good results were obtained when the weight percent of the intumescent additive (I), relative to the total weight of the composition (C) is between 25-40 wt.%. The inventors have found that in this range, the composition (C) performs well is the fire test while maintaining a good mechanical stability.

The particle size of any further intumescent additive (I), as used in the intumescent composition (C), is advantageously equal to or less than 1.5 mm, preferably equal to or less than 1.0 mm, more preferably equal to or less than 0.75 mm, even more preferably equal to or less than 0.65 mm, most preferably equal to or less than 0.55 mm.

It is further understood that, the lower limit of the particle size of the intumescent additive (I) is not particularly limited but advantageously equal to or more than 0.05 mm, preferably equal to or more than 0.1 mm, more preferably equal to or more than 0.15 mm, even more preferably equal to or more than 0.20 mm, most preferably equal to or more than 0.25 mm.

Good results were obtained when the particle size of the intumescent additive (I) is between 0.25 - 0.55 mm.

Generally, particle sizes such as the size of the intumescent additive (I) as defined above, may be measured by known methods in the art, in particular by sieving with screens as notably described in ISO 8397:1988, the whole content of which is herein incorporated by reference.

It is understood that the particle size expressed in mm refers to the median (or geometric mean) of the particle sizes corresponding to P(X<x) = 50 wt. %, wherein X is the particle size expressed in mm, P is the percentage by weight of particles smaller than the sieve screen size x expressed in mm, relative to the total weight of the sieved sample. FILLER (F)

In step 1 of the method of the present invention use is made of at least one intumescent composition (C) comprising 0-78 wt.% of at least one filler (F).

Typical fillers (F) suitable for use in the intumescent composition (C) in the method of the present invention include, but are not limited to, natural, grounded or precipitated calcium carbonates which are optionally coated with fatty acids, calcium silicates, dolomites, molochites, apatite, talc, precipitated silica, silicic anhydride, aqueous silicic acid and carbon black, magnesium carbonate, diatomaceous earth, kaolin or china clay, calcined clay, clay, heavy spar, titanium oxide, titanium dioxide, aluminum oxide, aluminum phosphates, Mg(OH)2, chalk, aluminum hydroxide, aluminum trihydrate (ATH), flint powder, bentonite, ferric oxide, zinc oxide, zinc borate, quarts, active zinc white, glass balloon, mica, wollastonite, resin powders such as PVC or PMMA powder, hollow beads, inorganic fibers such as glass fibers or mineral fibers, or mixtures of two or more thereof.

Preferably, the filler (F) may be chosen among the group of kaolin or china clay, calcined clay, clay, heavy spar, titanium dioxide, aluminum trihydrate (ATH), bentonite, mica, wollastonite, glass fibers or mixtures of two or more thereof. More preferably, the filler (F) may be chosen among the group of kaolin or china clay, aluminum trihydrate (ATH), mica or glass fibers or mixtures of two or more thereof. Most preferably, the filler (F) is kaolin, aluminum trihydrate (ATH) or glass fibers or mixtures of two or more thereof.

When clays, kaolin or mica are used as fillers (F), it is preferable for them to be present as nanoparticles in the composition (C).

Non limitative examples of commercially available fillers (F) suitable for use in the intumescent composition (C) in the method of the present invention include: the Polwhite™ series from Imerys, in particular Polwhite™ E, SH 10 from Dadco Alumina and Chemicals Limited, KB-30 from Hubron Speciality Limited, Actilox® 200 SM and Apyral® 15 or 25 from Nabaltec AG; Ti-Pure™ R706 from DuPont and the KaMin® series from Krahn Chemie Benelux.

In a preferred embodiment of the method of the present invention, the weight percent of the filler (F) as used in the intumescent composition (C) in step 1 , relative to the total weight of the composition (C), is advantageously equal to or greater than 0.50 wt.%, preferably equal to or greater than 0.75 wt.%, more preferably equal to or greater than 1.0 wt.%, even more preferably equal to or greater than 1 .25 wt.%, most preferably equal to or greater than 1 .5 wt.%.

It is further understood that, the weight percent of the filler (F), relative to the total weight of the composition (C), is advantageously equal to or less than 70 wt.%, preferably equal to or less than 50 wt.%, more preferably equal to or less than 30 wt.%, even more preferably equal to or less than 25 wt.%, most preferably equal to or less than 20 wt.%.

Good results were obtained when the weight percent of the filler (F), relative to the total weight of the composition (C) is between 1.5-20 wt.%. The inventors have found that in this range, a more economical composition (C) can be provided which also exhibits a good stability in the extrusion process while maintaining a good mechanical stability overall.

INTUMESCENT COMPOSITION (C)

As said, the present invention provides a method for additive manufacturing of intumescent products (IP) comprising as a first step providing at least one intumescent composition (C), wherein the intumescent composition (C), relative to the total weight of the composition (C), comprises:

20-80 % by weight (wt.%) of at least one binder polymer (P);

2-80 wt.% of intumescent additive (I), comprising expandable graphite and preferably one or more further intumescent additives;

- 0-78 wt.% of a filler (F);

It has now been surprisingly found that an intumescent composition (C) having a homogeneous distribution of all components is obtained by intimate admixing of the different components in the amounts as detailed above, while still providing a material having a useful balance between processability, handling strength and intumescent properties.

In a preferred embodiment, the intumescent composition (C) for use in the method of the present invention is prepared by the intimate admixing of 20-80 wt.% of the at least one binder polymer (P), as detailed above, with 2-80 wt.% of at least one intumescent additive (I), as detailed above, and 0-78 wt.% of at least one filler (F), as detailed above. The intimate admixing may be performed by a variety of conventional mixing or compounding techniques known to those skilled in the art.

A melt compounding technique is preferred. One skilled in the art can make appropriate decisions and/or experimentally determine appropriate compounding conditions. Melt compounding may be accomplished in any suitable melt compounding equipment by any suitable method.

Melt compounding is a solvent-free process that permits direct fabrication of an intumescent composition eliminating the need for drying the material after compounding and eliminating the need for additional water-based or organic solvent-based additives.

Typically, the intimate admixing is carried out by using one or a combination of mixing and laminating devices including cone screw blenders, screw blenders, double cone blenders, vertical mixers (e.g. Haake mixer), horizontal mixers (e.g. Sigma blade or Kneader), extruders (e.g. twin screw extruders, co-rotating double screw extruders), and the like so as to obtain a physical mixture. Preferably, the intimate admixing is carried out by using an extruder.

The order of addition of each component, is not particularly limited in the respective composition (C). In general, however, the binder polymer (P) is added to the mixer or extruder first and the intumescent additive (I) and the filler (F) are added next or in case of an extruder, in a separate zone further down the extruder for example by using a side feeder. The different components may be added in powder form or in the form of granules.

The intimate admixing may be done in batches or continuously and is preferably performed at a temperature of about 190°C or less, preferably about 170°C or less, preferably about 160°C or less, more preferably about 150°C or less. The person skilled in the understand that the temperature should be sufficiently less than the activation temperature (e.g. about 170-190 °C for expandable graphite) of the intumescent additive (I) so that the intumescent composition (C) may be safely compounded without activating the intumescence.

In a particular embodiment, the intumescent composition (C) for use in the method of the present invention is prepared by using an extruder having at least two temperature zones, wherein the binder polymer (P) is added to a first zone and the intumescent additive (I) is added to a second zone, wherein the first zone has a higher temperature than the second zone.

For example, the binder polymer (P) can be introduced into the extruder in a first zone at a temperature between 135-155 °C, preferably 140-150 °C, optionally together with other components such as the filler (F), the rheology modifier (R), the processing aid (A), the flame retardant (FR) and/or the additional ingredients (Al), while the intumescent additive (I) is added to the extruder by means of a side-feeder in a second zone further down and having a temperature between 115-135°C, preferably 130-120°C, optionally together with other components such as the filler (F), the rheology modifier (R), the processing aid (A), the flame retardant (FR) and/or the additional ingredients (Al), in particular when they were not introduced to the first zone together with the binder polymer (P).

One skilled in the art can make appropriate decisions and/or experimentally determine appropriate extrusion conditions such as the used nozzle or dye, the feeding speed, optional cooling, screw rotation speed and so on, which also depend on the respective intumescent composition (C).

The intumescent composition (C), and hence the intumescent product (IP) manufactured thereof, reacts under the influence of heat to swell to many times its original thickness, producing an insulating char that protects a substrate, to which the intumescent product (IP) is applied, from the effects of fire. The ratio of the thickness in the expanded state to the thickness in the unexpanded state is called the expansion ratio. In a particular embodiment, the intumescent composition (C) as used in the method of the present invention beneficially has an expansion ratio of about 5 or greater, preferably about 10 or greater, more preferably about 15 or greater. Preferably, the expansion ratio is in a range of about 10-60, or about 15- 60, or about 10-40. More preferably, the expansion ratio is about 15-35.

According to certain embodiments, the intumescent composition (C) may further comprise at least one fire retardant (FR).

Said fire retardants (FR) are known to those skilled in the art.

Among fire retardants (FR) suitable for use in the intumescent composition (C) of the method of the present invention, mention may be notably made of: inorganic and organic flame retardants including metal hydroxides such as aluminium trihydroxide (ATH), magnesium dihydroxide (MDH) (milled, ground or precipitated), in particular without or with surface treatment, for example to improve filler dispersion mechanical properties and so on; silicates such as talc or nanoclay (e.g. magnesium aluminium silicate), silica, phyllosilicates such as montmorillonite, kaolinite, mica; carbonates such as calcium carbonate, magnesium carbonate; microgranulated nanoclay such as montmorillonite, bis(hydrogenated tallow alkyl)dimethyl salt with bentonite such as Cloisite 20 (from BYK additives); metal oxides such as magnesium oxide, zinc oxide, antimony oxide, iron oxide for example mainly in synergy with ATH or MDH; aluminium oxide hydroxide (y- AIO(OH)) mineral or boehmite (antidripping action); tin components such as zinc stannate, zinc hydroxystannate; molybdate compounds such as zinc molybdate, in particular as smoke suppressant, and more preferred zinc molybdate precipitated on an inorganic core such as zinc borate or magnesium hydroxide; phenol formaldehyde resins (PF) or phenolic resins; halogenated components such as brominated components, chlorinated paraffin and PTFE; boron containing compounds such as boric acid and zinc borate; organic or inorganic phosphorous containing flame retardants including organophosphorus, red phosphorous, phosphoric acid derivatives, (oligomeric) phosphate esters, phosphate derivatives, ammonium polyphosphate (APP), tricresyl phosphate (TCP), triphenylphosphate (TPP), 2-ethylhexyldiphenylphosphate, metal phosphinates such as aluminium diethyl phosphinate, polyhedral oligomeric silsesquioxane (POSS), diguanidine phosphate, melamine phosphate, melamine polyphosphate, and melamine homologues such as melam, melem, or melon, coated ammonium polyphosphate, ammonium polyphosphate coated with melamine formaldehyde, alkyl phosphates, haloalkyl phosphates, products of reaction of urea or guanidyl urea with phosphoric acids or product of reaction of ammonia with P2O5; melamine cyanurate, magnesium sulphate, or mixtures of two or more thereof.

Preferred fire retardants (FR) suitable for use in the intumescent composition (C) of the method of the present invention are inorganic fire retardants (FR) and may be chosen among the group of metal hydroxides such as aluminum trihydrate; melamine phosphate; ammonium polyphosphate (APP) and diguanidine phosphate.

Non limitative examples of commercially available fire retardants (FR) suitable for use in the intumescent composition (C) in the method of the present invention include: FR CROS® series, in particular S10, available from Budenheim ; Melapur® MP available from BASF; Exolit® AP series, in particular 422, 462 and 468 available from Clariant and NORD-MIN® JLS APP available from Hangzhou JLS Flame Retardants Chemicals Co. Ltd..

Typically, the amount of the fire retardant (FR), when present, is from 5 wt.% to 25 wt.%, more preferably from 7.5 wt.% to 20 wt.%, most preferably from 10 wt.% to 15 wt.%, relative to the total weight of the composition (C).

In order to facilitate melt compounding the composition (C), it may be useful to include one or more rheology additives (R) or processing aids (A). The skilled person understands that some of these rheology additives (R) or processing aids (A) may also evaporate during compounding so that they do not remain in the intumescent composition (C).

According to certain embodiments, the intumescent composition (C) may According to certain embodiments, the intumescent composition (C) may further comprise at least one rheology additive (R).

Said rheology additives (R) are known to those skilled in the art.

Among rheology additives (R) suitable for use in the intumescent composition (C) of the method of the present invention, mention may be notably made of: silanes, aminosilanes, siloxanes, polysiloxanes, ultra-high molecular weight polysiloxanes, diguanidine phosphate, phthalic acid ester compounds such as dibutyl phthalate, diisononyl phthalate (DINP), diheptyl phthalate, di(2- ethylhexyl)phthalate, diisodecyl phthalate (DIDP), and butyl benzyl phthalate; terephthalic acid ester compounds such as bis(2-ethylhexyl)-1 ,4- benzenedicarboxylate; non-phthalic ester compounds such as 1 ,2-cyclohexane dicarboxylic acid diisononyl ester, aliphatic polycarboxylic acid ester compounds such as dioctyl adipate, dioctyl sebacate, dibutyl sebacate, diisodecyl succinate, and tributyl acetylcitrate; unsaturated fatty acid ester compounds such as butyl oleate and methyl acetyl ricinoleate; alkyl sulfonic acid phenyl esters; phosphoric acid ester compounds such as tricresyl phosphate and tributyl phosphate; trimellitic acid ester compounds; chlorinated paraffin; hydrocarbon oils such as alkyl diphenyl and partially hydrogenated terphenyl; process oil; and epoxy plasticizers such as epoxidized soybean oil and benzyl epoxystearate, vinyl polymers obtained by polymerizing vinyl monomers by various methods; esters of polyalkylene glycols, such as diethylene glycol dibenzoate, triethylene glycol dibenzoate, and pentaerythritol ester; polyesters formed from dibasic acids (e.g. sebacic acid, adipic acid, azelaic acid, phthalic acid) and divalent alcohols (e.g. ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol); polyethers such as polyether polyols (e.g. polyethylene glycol, polypropylene glycol, and polytetramethylene glycol having a number average molecular weight of 500 or more, or even 1000 or more) and derivatives obtained by converting the hydroxyl groups of these polyether polyols into ester groups, ether groups, or the like; polystyrenes such as polystyrene and poly-a-methylstyrene; polybutadiene, polybutene, polyisobutylene, butadiene-acrylonitrile, and polychloroprene, or mixtures of two or more thereof.

Non limitative examples of commercially available rheology additives (R) suitable for use in the intumescent composition (C) in the method of the present invention include: Jeffamine® grades from Huntsman, the Boltorn® grades from Perstorp, the Pluriol® grades from BASF, the Pluronic® grades from BASF, the Lutensol® grades from BASF, Voranol™ grades available from The DOW® Chemical Company and Genioplast® grades available from Wacker Chemical Corporation.

Typically, the amount of the rheology additive (R), when present, is from 0.5 wt.% to 20 wt.%, more preferably from 1 wt.% to 15 wt.%, most preferably from 2 wt.% to 10 wt.%, relative to the total weight of the composition (C).

According to certain embodiments, the intumescent composition (C) may further comprise at least one processing aid (A). The inventors have found that including a processing aid, among other things, may lead to a lower machine pressure, hence easier processing of the composition (C).

Said processing aids (A) are known to those skilled in the art.

Among processing aids (A) suitable for use in the intumescent composition (C) of the method of the present invention, mention may be notably made of: functionalized or non-functionalized waxy polymers including homopolymers and copolymers of various olefins such as ethylene, propylene, butylene, pentene, hexylene, heptene and octene, of natural or synthetic origin, including vegetable waxes, animal waxes, microcrystalline waxes, mineral waxes, paraffin waxes and petrochemical waxes such as polypropylene grafted with maleic anhydride, polypropylene or polyethylene grafted with acrylic acid or maleic anhydride, copolymerized waxes include terpolymer of ethylene-acrylic ester-maleic anhydride and ethylene-acrylic ester- glycidyl methacrylate, oxidized polyethylene homopolymers including high density oxidized polyethylene homopolymers and rosin esters.

Preferred processing aids (A) suitable for use in the intumescent composition (C) of the method of the present invention may be chosen among the group of functionalized waxy homopolymers and copolymers of propylene, more preferably a maleated homopolymers and copolymers of propylene, most preferably a maleated homopolypropylene.

Non limitative examples of commercially available processing aids (A) suitable for use in the intumescent composition (C) in the method of the present invention include: the Epolene® series, in particular Epolene® E such as Epolene® E43, available from Westlake Chemical Corporation, PolyBond™ from Chemtura Corp, Exxelor™ from ExxonMobil Chemical, Fusabond™ from The DOW® Chemical company.

Typically, the amount of the processing aid (A), when present, is from 0.05 wt.% to 10.0 wt.%, more preferably from 0.1 wt.% to 7.5 wt.%, most preferably from 0.2 wt.% to 5.0 wt.%, relative to the total weight of the composition (C).

According to certain embodiments, the intumescent composition (C) may further comprise other common additional ingredients (Al) to enhance the appearance, storage, transport, handling and/or performance of the product. Said ingredients (Al) are known to those skilled in the art of intumescent compositions. Typical ingredients (Al) may include, but are not limited to, charring catalyst (acid donor); charring agent; blowing agent; stabilizers to protect from light, heat and/or UV-radiation; dispersants, such as, for example, zinc stearate or calcium stearate, glyceryl stearate, pentaerythrityl tetrastearate, cetyl palmitate, ethylenedistearoyldiamide, C14-C18 fatty alcohols, dicarboxylic esters, fatty amines, paraffins; solvents; pigments; curability modifiers; radical inhibitors; metal deactivators; antiozonants; phosphorus peroxide decomposers; lubricants; adhesion promoters and crosslinkers such as epoxysilanes, (meth)acrylsilanes, anhydrosilanes or hydroxyl functional silanes; moisture scavengers such as vinyltrimethoxysilane, a-functional silanes, ortho formic acid esters, calcium oxide or molecular sieves; surface-active substances such as wetting agents, leveling agents, air release agents or defoamers; biocides such as algicides, fungicides or fungal growth inhibitors; and other substances typically used in intumescent compositions. Typically, the amount of the ingredient (Al), when present, is from 0.05 wt.% to 20 wt.%, more preferably from 0.1 wt.% to 10 wt.%, most preferably from 0.1 wt.% to 5 wt.%, relative to the total weight of the composition (C).

As said, the sum of all the components of composition (C), excluding the at least one binder polymer (P), is equal to or less than 80 wt.%.

In a preferred embodiment of the method of the present invention, the sum of all the components of composition (C), excluding the at least one binder polymer (P), relative to the total weight of the composition (C), is advantageously equal to or less than 75 wt.%, preferably equal to or less than 70 wt.%.

It is further understood that, the lower limit of the sum of all the components of composition (C), excluding the at least one binder polymer (P), relative to the total weight of the composition (C), is not particularly limited but advantageously equal to or greater than 20 wt.%, preferably equal to or greater than 25 wt.%, more preferably equal to or greater than 30 wt.%, even more preferably equal to or greater than 35 wt.%, yet even more preferably equal to or greater than 40 wt.%, most preferably equal to or greater than 45 wt.%.

The inventors have found that the total filling grade of the composition (C) should not be greater than 80 wt.%, preferably not greater than 70 wt.% in order to maintain a composition (C) with an acceptable mechanical stability.

The “total filling grade” refers to the sum or the total weight percent of all the possible components of the composition (C), such as the intumescent additive (I), the filler (F), the rheology additive (R), the processing aid (A), the fire retardants (FR) and/or the additional ingredients (Al), but excluding the weight percent of the binder polymer (P).

ADDITIVE MANUFACTURING MACHINE

Thus, in step 2 of the method according to the present invention, use is made of an additive manufacturing machine (AMM) or 3D printer, preferably using a monofilament additive manufacturing technique, to form a three- dimensional intumescent product (IP).

It is further understood that all definitions and preferences as described above for composition (C) as provided in step 1 of the method according to the present invention, equally apply for this embodiment and all further embodiments, as described below. In the present description “monofilament” or “filament” designates an additive manufacturing machine (AMM) or 3D printer feeding form or feedstock composition that has the shape of a fine wire. Equivalent and interchangeable feeding forms may be selected from at least one bullion, at least one rod or stick, at least one pellet or granule, a powder. A person skilled in the art can easily determine the feeding form of the material, depending on the type of the additive manufacturing machine (AMM) or 3D printer used and can easily adapt the composition (C) to the feeding form if needed, for example to feeding forms for SLA/DLP and Multi Jet Fusion (MJF) printing technologies.

In a particular embodiment of the method according to the present invention, the composition (C) is in the form of granules or pellets.

Some AMM or 3D printers can use pellets or granules as input materials including, but not limited to, the commercially available Freeformer from Arburg, Lossburg, Germany, useful for carrying out a process known under the trade designation "ARBURG PLASTIC FREEFORMING (APF)", and those described in US8292610B2.

In one embodiment, the composition (C) as provided in step 1 of the method according to the present invention, is in the form of a monofilament, a powder, granules or pellets.

In a preferred embodiment, the composition (C) as provided in step 1 of the method according to the present invention, is in the form of a monofilament.

Preferably, the diameter of the monofilament is from about 1 to about 3.5 mm, more preferably from about 1.75 to about 3.25 mm, even more preferably the diameter is from 2.0 mm to 3.00 mm.

The diameter of the monofilament can be determined on the basis of the type of impression and easily determined by a person skilled in the art. The diameter of the monofilament is measured by an electronic slide gauge, preferably the electronic slide gauge is the RS ProOelectronic digital caliper 150 mm/6.

In one embodiment of the method according to the present invention, the diameter of the monofilament is regular throughout its length.

In one embodiment of the method according to the present invention, the monofilament presents a length from about 1 to about 3000 m, preferably from about 40 to about 1500 m , more preferably from about 80 to about 1200 m , even more preferably from about 90 to about 1100 m.

Advantageously, the monofilament is flexible and can be coiled.

The inventors have found that a regular additive manufacturing machine or 3D printer can be used in the method according to the present invention, however, preferably some modifications are made to the machine in order to allow for a better handling of the intumescent composition (C), preferably in the form of a monofilament, as detailed above.

The inventors have found that it is advantageous to adapt the feeder of the AMM or 3D-printer by inserting a tubing which minimizes the distance wherein the monofilament is unsupported, and which allows to use more flexible monofilaments without bending or breaking of the monofilament.

In one embodiment of the method according to the present invention, the AMM or 3D-printer comprises a modified feeder system having a feeder wheel and a monofilament input opening, wherein the feeder system comprises a tubing between the feeder wheel and the monofilament input opening.

The inventors have further found that it is advantageous to use nozzles having a bigger diameter than regular nozzles to handle the intumescent composition (C).

In one embodiment of the method according to the present invention, the AMM or 3D-printer comprises a nozzle having a nozzle hole diameter between 0.9 and 1.5 mm, preferably between 0.95 and 1.25 mm, more preferably between 1.0 and 1.2 mm.

In an alternative embodiment of the method according to the present invention, the AMM or 3D-printer comprises a direct drive feeder.

The inventors have further found that it is advantageous to use a printing bed cover having a structured surface such as a structured masking tape.

In one embodiment of the method according to the present invention, the AMM or 3D-printer comprises a structured printing bed or a printing bed cover having a structured surface. It is further understood that all definitions and preferences as described above for the additive manufacturing machine (AMM) as used in step 2 of the method according to the present invention, equally apply for this embodiment and all further embodiments, as described below. A further aspect of the present invention is an additive manufacturing machine (AMM) or 3D printer, preferably using a monofilament additive manufacturing technique, as used in step 2 of the method of the present invention, as detailed above, to form a three-dimensional intumescent product (IP).

It is also a further aspect of the present invention to provide computer instructions which cause an additive manufacturing machine or 3D printer to manufacture said three-dimensional intumescent product (IP).

The computer instructions may include a CAD-file with the specifications and dimensions of the product to be printed.

In general, the model of the intumescent product (IP) is first generated/designed via a computer-aided design (CAD)-software (e.g. Solidworks 3D, AutoCAD, ...) and exported into a suitable format (e.g. .stl or .obj). Scanning methods to scan a three-dimensional object may also be employed to create the data representing the article. One exemplary technique for acquiring the data is digital scanning. Any other suitable scanning technique may be used for scanning an article, including X-ray radiography, laser scanning, computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound imaging. The initial digital data set, which may include both raw data from scanning operations and data representing articles derived from the raw data, can be processed to segment an article design from any surrounding structures (e.g., a support for the article).

The obtained CAD-file can then be read by a slicer software (Cura, OctoPrint, Simplify3D, ...) which slices the model into multiple horizontally sliced layers and generates the printer paths for each layer, also called expression rendition. These build paths are then exported to a printer readable format by the slicer software.

It is understood that these build paths can accordingly be of low resolution meaning thick layers, creating a higher surface roughness but quick to print, or of high resolution which is aesthetically pleasing but more time consuming to print. Low resolution layers will also build in more heat into the printed product which puts some very specific demands on the composition (C) to be used in order to avoid gravity induced shrinkage, also known as Z-axis shrinkage.

Movement of the extrusion head of the AMM or 3D printer with respect to the substrate onto which the substrate is extruded is performed under computer control, in accordance with build paths that represent the three-dimensional product.

In an advantageous embodiment of the method according to the present invention, the second layer or second rendition printing can advantageously be guided by a sensor. The result of the first rendition printing and/or the second rendition printing is accordingly continuously or discontinuously scanned via laser scanner or another optical device. These measurements of the partly printed product (IP) are then compared with the digital version of the design and the printing is adjusted to compensate for deviations from the digital version. Such a method of guiding the printing process can of course be completely automated through algorithms in the guiding programming of the printer. It will of course also be possible to utilize such guiding also for the printing of the first rendition.

In some embodiments, a (e.g., non-transitory) machine-readable medium is employed in the method according to the present invention. Data is typically stored on the machine-readable medium. The data may represent a three- dimensional model of an intumescent product (IP), which can be accessed by at least one computer processor interfacing with an additive manufacturing machine (AMM) (e.g. a 3D printer). The data is used to cause the additive manufacturing machine (AMM) to create the three-dimensional intumescent product (IP).

As discussed above, gravity induced, or so-called Z-axis shrinkage is a common problem in FDM technology. This Z-axis shrinkage is of course affected by the mechanical properties of the composition (C) but will of course be affected also by the design of the product to be printed. Especially top-heavy designs will suffer more from Z- axis shrinkage than bottom heavy designs.

According to one embodiment of the method of the present invention, the first rendition is being printed with a composition (C) by means of a AMM or 3D printer having a CAM (Computer Aided Manufacturing) guided heated nozzle moveable in at least 3-axis, said nozzle being used for printing the composition (C).

According to one particular embodiment of the method of the present invention the AMM or 3D printer has a CAM guided cooling nozzle. This cooling nozzle is used for rapidly cooling and setting the newly printed composition (C). An effluent selected from the group consisting of; liquid carbon dioxide, liquid water, cooled air and a combination thereof, is supplied to the cooling nozzle. Advantageously, the position of the cooling nozzle and the amount of effluent ejected from the cooling nozzle is guided through means of algorithms calculated to create an even temperature profile in newly printed composition (C) and to counteract hot-spots in the products caused by parts of the product with low surface to mass ratio. The cooling nozzle can possibly be arranged adjacent to the CAM guided heated nozzle. The cooling nozzle is then suitably guided in at least 4-axis as in relation to the printed product.

One should note that the above described forced cooling method, including the effluent selected, needs to be adapted to the composition (C) used. Some compositions (C) such as those comprising lactic acid or caprolactone based polyester thermoplastics (PLA and PCL respectively) as binder polymer (P) will not obtain their full mechanical strength if cooled too rapidly, while other compositions (C) such as those comprising a polyolefin thermoplastic as binder polymer (P) can accept more rapid cooling. It will however still be possible to utilize a balanced cooling even in more sensitive composition (C) selections to counteract hot-spots in parts of the printed product with heavier goods thickness.

It is further understood that all definitions and preferences as described above for composition (C) as provided in step 1 of the method according to the present invention, equally apply for this embodiment and all further embodiments, as described below.

Another aspect of the present invention is the intumescent composition (C) provided in the method according to the present invention.

A further aspect of the present invention is a three-dimensional intumescent product (IP) manufactured according to the method of the present invention and comprising the composition (C), as detailed above.

The intumescent product (IP) manufactured according to the method of the present invention preferably forms all or part of a passive fire protection element, such as a plug, pipe collar or sleeve, cable sleeve, brick, fire and smoke dampers, ventilation grille, closures for conveyors, seals, electrical component, for example a conduit or conduit coupling, a socket box, or a switch box.

In contrast to other forming processes such as injection molding, blow molding, and sheet extrusion, the three-dimensional intumescent product (IP) manufactured according to the method disclosed herein may have a higher surface roughness with vertical deviation of at least 0.01 millimetres (mm), particularly when a fused filament deposition method is used. However, the rough surface has very regular appearance so that the products are still useful and attractive in quite some applications, as detailed above. In any event, the products (IP) manufactured according to the method disclosed herein are very suitable for rapid prototyping. Furthermore, in situations where a smoother surface is desired, the initially formed rough grooved surface may be removed in subsequent operations, examples of which include sanding, peening, shot blasting, or laser peening.

In an advantageous embodiment, the method of the present invention further comprises the steps of: Step 3: providing at least one second material, preferably in the form of a monofilament;

Step 4: melting said second material and printing the second material in molten form using an additive manufacturing machine or 3D printer, preferably by using a monofilament additive manufacturing technique, to form a two-component intumescent product (IP) comprising the second material and the composition (C) as a first material.

The method according to the present invention allows for the manufacturing of composite or “2K” products comprising a first material, which comprises the intumescent composition (C), and a second material.

The person skilled in the art understands that the composition (C) may be printed before, simultaneous to or after the second material.

The second material in such products preferably has a reflective surface, for example in a lighting component, or has an aesthetic function to cover, at least partially, the first material comprising the composition (C).

In an advantageous embodiment, the intumescent product (IP) as manufactured by the method of the present invention may beneficially protect the substrate from fire for at least about 30 minutes, preferably at least about 60 minutes, more preferably at least 90 minutes and even more preferably at least 120 minutes in accordance with standard methods of fire endurance tests of building construction (NBN EN 1363, 1364, 1366 and 13501).

EXPERIMENTAL TEST RESULTS

The invention will be now described in more details with reference to the following examples, whose purpose is merely illustrative and not intended to limit the scope of the invention. General procedure for producing an intumescent composition (C) according to the invention.

A composition (C), according to the invention, is prepared by mixing a binder polymer (P), according to the invention, with an intumescent additive (I), according to the invention, optionally a filler (F), a rheology additive (R), a processing aid (A) and a fire retardant (FR), and/or optionally an additional ingredient (Al), according to the invention. The mixing was performed by using a lab scale co-rotating double screw extruder (Leistritz) using a dye with three holes of a diameter of 2.85 mm, a screw rotation speed of 51 rotations/minute and a feeding rate of 10 kg/h. The binder polymer (P) was fed into the first zone of the extruder while the other components were fed through a side feeder in a fifth zone of the extruder. Each extruder zone having a predetermined temperature:

The extruded composition (C) was cooled with water. The list of used materials according to the invention can be found in Table 1.

TABLE 1 : LIST OF PRODUCTS AND DESCRIPTION

Extrusion tests

Examples 1 to 14 according to the invention

Examples 1 to 14, as detailed in Tables 2, 3 and 4 below, show different compositions (C) that can be prepared according to the general procedure detailed above.

TABLE 4: COMPOSITION (C) WITH PLA BINDER POLYMER (P)

In Table 2, all compositions (C) have different binder polymers (P). Diguanidine phosphate was used as a rheology additive (R) as well as a flame retardant (FR).

In Table 3, all compositions (C) have the same binder polymer (P). However, to reduce the amount of diguanidine phosphate used, the flame retardant (FR) was replaced. Furthermore, in Examples 5-8, the amount of binder polymer (P) and processing aid (A) was increased while the amount of the other components was decreased.

In Examples 9-12, the graphite was sieved by using a lab size sieving machine with mesh sieves having a mesh width of 0.5 mm to retain a particle size of 0.5 mm prior to adding to the extruder.

In Example 11 , the flame retardant (FR) MP was replaced with APP. In Example 12, the flame retardant (FR) MP was replaced with APP and the diguanidine phosphate rheology additive (R) was replaced with PEG to provide a diguanidine phosphate free variety.

In Table 4, the binder polymer (P) is PLA. In Example 14, the diguanidine phosphate rheology additive (R) was replaced with polydimethylsiloxane to provide a diguanidine phosphate free variety.

All compositions generate an extruded monofilament suitable for use in the AM method according to the present invention.

3D printing tests

Examples 15 to 17 according to the invention

The monofilaments produced in Examples 10 to 12 were used in an additive manufacturing method according to the present invention. The filaments were fed to a lab scale 3D-printer using a FDM printing technique (CREATBOT DX-Plus) which was adapted by introducing a tubing between the feeding wheel of the printer and the filament input and by using a 1mm nozzle. The printing bed was covered with a structured tape. The 3D printer was instructed to print three-dimensional intumescent products (IP) with the same shape as the injection molded products Promastop(B^IM Grille, a ventilation grille with dimensions (HxWxD) 100x100x80mm, and Promastop(B^IM CJ21 , a cable sleeve with dimensions 40 mm (height) x 26 mm (outer diameter) and a wall thickness of 1.5 mm.

TABLE 5 : NOTES ON 3D PRINTING FOR EXAMPLES 15 TO 17

Fire tests

The three-dimensional intumescent products (IP) according to the invention produced in Examples 15 and 16, products E15 and E16 respectively, were subjected to fire testing and the results are compared to their injection molded counterparts as a comparative example 18 and 19 or products CE18 and CE19. The test wall was constructed out of one porous concrete block (size 1000x500x100mm), cut-outs (-100x100mm) and holes 40mm for the test specimens were cut into the block: a 15 cm strip was cut off on top, the block was ll-cut with a saw and the strip was put on top again and fixed with screws. The specimens were placed in the cut-outs and any gaps between the wall and the ventilation grilles were sealed with PROMASEAL®-A.

The cable sleeves were installed on the fire and the cold side.

In the first fire test for E15 and CE18, the temperature curve was an ISO curve according to ONORM EN 1363-1 , Pkt. 5.1.1 and the oven pressure was 20 Pa. Plate thermocouples were used to control the furnace temperature and the ambient temperature and relative humidity at the start of the test was 11 ,0°C and 43%. The test was stopped after 132 minutes. TABLE 6 : RESULTS FIRE TEST E15 AND CE18

From the results of the first fire test as shown in Table 6 above, it is clear that the bigger fire stopping components, the ventilation grilles, easily reach a fire resistance of more than one hour. The smaller components, the cable sleeves, easily reach a fire resistance of more than two hours. The test was stopped after 132 minutes but the cable sleeves, both the 3D printed one as well as the injection molded one, were still structurally intact. In the second fire test, for E16 and CE19, the furnace was controlled using furnace thermocouple locations in accordance with EN 1363-1. The fire test curve was an ISO curve. Plate thermocouples were used to control the furnace temperature and the ambient temperature and relative humidity at the start of the test was 19.0°C and 41.0% respectively. The test was stopped after 206 minutes.

TABLE 7: RESULTS FIRE TEST E16 AND CE19

From the results of the second fire test as shown in Table 7 above, it is again clear that the bigger fire stopping components, the ventilation grilles, easily reach a fire resistance of more than one hour. The smaller components, the cable sleeves, easily reached a fire resistance of more than three hours. The test was stopped after 206 minutes but again the cable sleeves, both the 3D printed one as well as the injection molded one, were still structurally intact.

Claims

-34-CLAIMS

1. An intumescent composition (C) for use in an additive manufacturing method comprising:

20-80 % by weight (wt.%) of at least one binder polymer (P);

20-80 wt.% of intumescent additive (I) comprising expandable graphite;

0-78 wt.% of at least one filler (F);

2. The composition according to any of the preceding claims, wherein the expandable graphite is present in an amount of 20-45wt%, preferably 25-40wt%.

3. The composition according to any of the preceding claims, wherein the expandable graphite has a particle size in the range of 0.2-0.6 mm as defined by sieving, preferably 0.3-0.5 mm as defined by sieving.

4. The composition according to any of the preceding claims, wherein the composition (C) comprises at least one binder polymer (P) selected from the group of polyolefins, such as polyethylene (PE) having a low density (LDPE) to high density (HDPE), polypropylene (PP), polyethylene-polypropylene copolymers, poly-l-butene, poly(methyl-pentene), copolymers of ethylene and octene, ethylene/propylene-diene terpolymers (EPDM); polylactic acid (PLA), polycaprolactone (PCL), acrylonitrile butadiene styrene (ABS), polyethylene terephthalate (PET), polyethylene trimethylene terephthalate (PETT), polyvinyl alchohol (PVA), polyamide (PA) or nylon, ethylene-vinyl acetate (EVA) copolymers, ethylene-butyl acrylate copolymers (EBA), polyvinyl chloride (PVC), acrylic polymers or copolymers, metallocene polymers, polyphthalamide (PPA), polystyrene (PS), high impact polystyrene (HIPS), silicone rubbers or polymers, latexes, styrene-ethylene-butylene-styrene (SEBS) or other thermoplastic elastomers (TPE), polycarbonate (PC), polyimides, polyetherimide (PEI), polyethersulfone (PES), polysulfone (PSU), polyphenylene oxide (PPO), polyphenylene ether (PPE), polyphenylene ether sulfone (PPSLI), styreneacrylonitrile (SAN), or silicone polycarbonate copolymers, or a mixture of two or more thereof, preferably from the group of polyolefins such as low-density -35 - polyethylene (LDPE) or high-density polyethylene (HDPE), polypropylene, polylactic acid (PLA), ethylene-vinyl acetate (EVA) copolymers, ethylene-butyl acrylate (EBA) copolymers, styrene-ethylene-butylene-styrene (SEBS) or other thermoplastic elastomers (TPE), or mixtures of two or more thereof, more preferably from the group of low-density polyethylene (LDPE), polylactic acid (PLA), ethylene-vinyl acetate (EVA) copolymers, ethylene-butyl acrylate (EBA) copolymers or mixtures thereof.

5. The composition according to claim 1-4, wherein the binder polymer is a polymer obtained by radical polymerization.

6. The composition according to claim 5, wherein the binder polymer is chosen from polyolefines, polyacrylates, polymethacrylates, polymethylmethacrylates and vinylic polymers.

7. The composition according to claim 4-6, wherein the binder polymer is a polymer with a melting temperature of at most 200°C, preferably at most 180°C.

8. The composition according to claim 4-6, wherein the binder polymer is a polymer with a melting temperature of at least 100°C, preferably at least 120°C.

9. The composition according to claim 1-8, wherein the composition (C) comprises at least one further intumescent additive (I) selected from the group of ammonium or amino compounds, such as, for example, ammonium polyphosphate, ammonium dihydrogen phosphate, ethylene-diamine phosphate, ammonium pentaborate, melamine; dicyandiamide, full phosphoric esters with polyols, dipentaerythritol, pentaerythritol, sugar, dextran, starch, vermicular graphite, exfoliating graphite, waterglass or sodium silicates, expanded mica, vermiculite, perlite, or mixtures of two or more thereof, preferably the group of ammonium polyphosphate, ethylene-diamine phosphate, dipentaerythritol, pentaerythritol, waterglass or sodium silicates, or mixtures of two or more thereof, more preferably the group of ammonium polyphosphate, melamine, pentaerythritol or mixtures thereof.

10. The composition according to any one of the preceding claims, wherein the composition (C) comprises at least one filler (F) selected from the group of natural, grounded or precipitated calcium carbonates which are optionally coated with fatty acids, calcium silicates, dolomites, molochites, apatite, talc, precipitated silica, silicic anhydride, aqueous silicic acid and carbon black, magnesium carbonate, diatomaceous earth, kaolin or china clay, calcined clay, clay, heavy spar, titanium oxide, titanium dioxide, aluminum oxide, aluminum phosphates, Mg(OH)2, chalk, aluminum hydroxide, aluminum trihydrate (ATH), flint powder, bentonite, ferric oxide, zinc oxide, zinc borate, quarts, active zinc white, glass balloon, mica, wollastonite, resin powders such as PVC or PMMA powder, hollow beads, inorganic fibers such as glass fibers or mineral fibers, or mixtures of two or more thereof, preferably the group of kaolin or china clay, calcined clay, clay, heavy spar, titanium dioxide, aluminum trihydrate (ATH), bentonite, mica, wollastonite, glass fibers or mixtures of two or more thereof, more preferably the group of kaolin or china clay, aluminum trihydrate (ATH), mica or glass fibers or mixtures of two or more thereof.

11 . The composition according to any one of the preceding claims, wherein the composition (C) further comprises a fire retardant (FR).

12. The composition according to any one of the preceding claims, wherein the composition (C) further comprises a rheology additive (R).

13. The composition according to any one of the preceding claims, wherein the composition (C) further comprises a processing aid (A).

14. The composition according to any one of the preceding claims, wherein the composition (C) has an expansion ratio of about 10 or greater, preferably about 15 or greater, preferably in a range of about 10-60, or about 15-60, or about 10-40 and more preferably in a range of about 15-35.

15. A method for additive manufacturing of three-dimensional intumescent products (IP) comprising:

20-80 % by weight (wt.%) of at least one binder polymer (P); 20-80 wt.% of intumescent additive (I) comprising expandable graphite;

0-78 wt.% of at least one filler (F);

16. The method according to claims15, further comprising:

Step 3: providing at least one second material, preferably in the form of a monofilament;

Step 4: melting said second material and printing the second material in molten form using an additive manufacturing machine or 3D printer, preferably by using a monofilament additive manufacturing technique, to form a two- component intumescent product (IP) comprising the second material and the composition (C) as a first material.

17. An additive manufactured three-dimensional intumescent product (IP) obtainable by the additive manufacturing method according to claims 1-9.

18. The additive manufactured three-dimensional intumescent product (IP) according to claim 11 having a fire resistance of at least about 30 minutes, preferably at least about 60 minutes, more preferably at least 90 minutes and even more preferably at least 120 minutes in accordance with standard EN1363- 1.

19. An additive manufacturing machine (AMM) or 3D printer suitable for use in the additive manufacturing method according to claims 1-9, for producing three-dimensional intumescent products (IP) according to claims 11-12 and comprising the composition (C) according to claim 10.

20. The additive manufacturing machine (AMM) or 3D printer according to claim 19 further comprising a modified feeder system having a feeder wheel and a monofilament input opening, wherein the feeder system comprises a tubing between the feeder wheel and the monofilament input opening.

21. Computer instructions which cause an additive manufacturing machine or 3D printer to manufacture the three-dimensional intumescent product (IP) according to claims 19-20. - 38 -

22. Use of a composition (C) as defined in claim 10, in additive manufacturing or 3D printing.