The invention relates to a method for packaging a particulate material, paste or gel, more in particular a solid industrial chemical.

Many particulate chemical compounds, including neat solid peroxides, solid peroxide formulations, and polymer additives are packaged in a flexible package, such as a (plastic) bag, which is subsequently packaged in a more rigid package, such as a (cardboard or fibreboard) box, or a (fibre) drum. The bag is the primary package; the box or drum is the transport package.

The packaging technology in general shows a broad range of performance requirements. Depending on the goods to be packaged, the packaging must fulfil a wide variety of properties. Besides the mechanical strength of the packaging materials, the ease or strength of opening, the options for dispensing, i.e. pouring, sucking or picking out, as well as the type of labelling is under permanent technical development.

The field of retail packing, in particular food packaging has a focus on sealing goods and ease of dispensing the packaged goods. Liquids are often contained in plastic and glass jars, bottles and tubs as well as plastic and paper bags including pouches, envelopes or stick packages.

The WO 2017/135927 A1 for instance refers to a bag-in-box package with a collapsed head-space. The package is provided for liquid or flowable products contained in a thermoplastic bag which is inserted in or encased within an outer relatively rigid box or carton. The package is equipped with an access port at a top part of the box for inserting a rigid implement, such as e.g. a drinking straw, with is punctured through the thermoplastic bag for getting access to the inside good.

Completely distinguishing requirements are addressed when packaging goods, which require certifications e.g. for safety reasons, in the following designated as certified goods. These goods may require certifications e.g. for the reason that they are dangerous goods. The way of getting access to the good must be safe. The package must be provided with a labelling. This labelling is associated with strict legal requirements. The box disclosed in WO 2017/135927 A1 is not suitable for packaging certified goods, in particular if the certified goods represent particulate materials, pastes or gels. Certified goods in these forms are often poured out after removal of a sealing strap at the top of the package. In case a package was provided with an access port in accordance with this state of the art package and in case this access port is punctured, the certified goods have air and moisture contact which is detrimental to certified goods or which may even be infringing legal requirements. A package of this kind is not suitable for packaging certified goods.

The United Nations’ Globally Harmonised System of Classification and Labelling of Chemicals (GHS), implemented by the EU as the Regulation on Classification, Labelling and Packaging of substances and mixtures (CLP Regulation), requires that information concerning chemical content and safety are both on the primary package and on the outside of the transport package. The GHS and CLP also require that this information is provided in the languages of all countries where the product is sold.

Once a certain product is re-classified, or the product will be sold to a new country, or amended regulations require different or additional information, the entire stock of pre printed bags has to be replaced by new ones containing the additional or amended information.

A potential solution to this problem would be the manual labelling of bags instead of pre printing them. However, that’s an unattractive job that requires employees being able to understand the label and the link with the product.

It is therefore an object of the present invention to provide a manner of packaging certified goods that solves this problem.

The solution is provided by attaching the flexible package to the inside of the rigid package, so that the combined package is considered the primary package and only the outside of the combined package has to be labelled.

The present invention therefore relates to a method for packaging a particulate material, paste or gel, said method involving the steps of:

- providing a rigid package, having a bottom, a top, and a vertical wall, said rigid package being opened at the top and containing an adhering layer on at least part of the inside bottom or inside vertical wall,

- filling a flexible package with particulate material, paste or gel,

- contacting the filled flexible package with the adhering layer, thereby adhering the flexible package to the rigid package,

- closing the rigid package, wherein the particulate material, paste or gel is a chemical compound requiring GHS and/or CLP labelling.

It is preferred that a particulate material is packaged. Therefore, in a preferred embodiment, the present invention relates to a method for packaging a particulate material, said method involving the steps of:

- providing a rigid package, having a bottom, a top, and a vertical wall, said rigid package being opened at the top and containing an adhering layer on at least part of the inside bottom or inside vertical wall,

- filling a flexible package with particulate material,

- contacting the filled flexible package with the adhering layer, thereby adhering the flexible package to the rigid package,

- closing the rigid package, wherein the particulate material is a chemical compound requiring GHS and/or CLP labelling.

The rigid package

The rigid package should be sufficiently rigid to keep its shape during transport, storage, and handling.

It preferably has a cylindrical, cubical, or cuboid shape.

The rigid package is preferably a box, drum, crate, or pail.

It is preferably made from (corrugated) cardboard, fibreboard, or plastic material.

The rigid package has a bottom, a top, and a vertical wall. The vertical wall of packages with cubical or cuboid shape consist of the four side walls. The vertical wall of packages with a cylindrical shape is the cylinder wall.

The inside bottom is the side of the bottom that faces the inside of the package. The inside vertical wall is the side of the wall that faces the inside of the package.

The method of the invention starts with a rigid package, opened at the top.

At the end of the method, the rigid package is closed, e.g. by folding and fastening (e.g. by gluing or taping) the closing flaps of the box or by placing a lid or cover. The particulate material, paste or gel is an industrial chemical compound. According to the invention, the particulate material, paste or gel is a chemical compound requiring GHS and/or CLP labelling.

The flexible package

The flexible package is the package that is filled with the particulate material, paste or gel. It preferably has the form of a bag, more preferably a plastic bag.

The plastic bag can be made from any plastic material suitable for making bags. A preferred material is polyethylene.

The plastic bag can have any suitable form. For instance, it may be a block bottom or round-liner bag or a sleeve-like bag with a bottom seem.

The outside bottom of the filled flexible package is defined as the part of the bag that will, once placed inside the rigid package, contact the inside bottom of the rigid package.

One-component adhesive

The adhering layer that is present on the inside bottom or vertical wall of the rigid package can be a one-component adhesive.

This one-component adhesive preferably is a pressure sensitive adhesive (PSA), i.e. an adhesive that forms a bond by bringing the adhesive film in contact with the substrate (i.e. the filled flexible package) and applying pressure. Pressure sensitive adhesives do not solidify to form a solid material, but remain viscous. As a result, they remain permanently tacky.

Pressure sensitive adhesives are typically formulated from elastomers (e.g. natural rubber, vinyl ethers, acrylics, butyl rubber, styrene block copolymers, silicones, nitriles, or chemical modified forms thereof), optionally including a tackifier (e.g. terpenes, aromatic resins, hydrogenated hydrocarbon resins, or terpene-phenol resins).

In a preferred embodiment, the adhesive is a removable or fugitive adhesive, i.e. a pressure sensitive adhesive that forms a temporary bond which can be removed after relatively long periods of time without leaving a residue on the adherent.

The pressure sensitive adhesive is applied on at least part of the inside bottom or inside vertical wall. In a preferred embodiment, it is applied on at least part of the inside bottom. In this embodiment, it may additionally be applied on at least part of the inside vertical wall, it so desired.

The adhesive is applied in a liquid form, e.g. as solution in organic solvent, as aqueous dispersion, or as a hot melt. The liquefied adhesive can be sprayed, roll coated, swirled, painted, or applied with a glue-gun.

In a preferred embodiment, the one-component adhesive is a hot melt PSA. Hot melt PSAs are typically based on styrene block copolymers or (chemically modified) ethylene co- or homopolymers, optionally formulated with oils, plastizers, and tackifiers. Even more preferably, the one-component adhesive is a removable hot melt pressure sensitive adhesive (HMPSA), as these adhesives can be easily peeled off without leaving residues.

The adhesive may also have the form of double-sided tape, although this is less preferred as it may be difficult to remove without leaving an adhesive layer on the rigid package after use.

The one-component adhesive is preferably applied on the inside bottom or vertical wall after assembling or opening the rigid package. The adhesive may be applied in various patterns, preferably such that a large contact area is obtained.

In a preferred embodiment, the flexible and rigid package can be detached after use by applying only little tear-force, so that they can be separately disposed of. This can be achieved by applying the adhesive in a spiral or swirl pattern. Provided that it is not chemically contaminated, the rigid package can be re-used, recycled or disposed as (paper or plastic) waste. The flexible package may be considered chemical waste and might require a different handling.

Two-component adhesive

The adhering layer that is present on the inside bottom or vertical wall of the rigid package may constitute the first component of a two-component adhesive. This component can be applied after assembling or opening the rigid package, but it may also be applied during manufacturing of the rigid package or on unfolded boxes.

The advantage of this embodiment is that the first component will only stick to the second component and not to other substrates, so that boxes containing a layer of the first component can be easily folded, unfolded, and stacked without sticking together.

The first component can be sprayed, printed, roll coated, dip-coated, swirled, painted, or applied with a glue-gun.

The first component is preferably applied to at least part of the inside bottom of the rigid package.

The second component of the adhesive is applied on the outside of the flexible package, preferably the outside bottom. It can be applied by spraying, printing, roll coating, dip coating, swirling, painting, or using a glue-gun.

This second component will only stick to the first component and not to other flexible packages, so that the flexible packages can be easily stacked without sticking together. Placing the filled flexible package onto the layer of first component in the rigid package will combine the two components, thereby adhering the packages.

This two-component adhesive is preferably a pressure sensitive adhesive, more preferably a removable pressure sensitive adhesive.

The two components should be applied to the flexible and the rigid package in a pattern that ensures a sufficiently large contact area between the two components is after insertion of the flexible package.

In a preferred embodiment, the flexible package and the rigid package can be easily detached after use so that they can be separately disposed of. Provided that it is not chemically contaminated, the rigid package can be re-used, recycled, or disposed as (paper or plastic) waste; the flexible package may be considered chemical waste and might require a different handling.

Hook-and-loop strip

In a further embodiment, the adhering layer constitutes one part of one of more hook- and-loop (e.g. Velcro) strips adhered to bottom or vertical wall of the rigid package; the opposite part of said strip(s) being adhered to the outside of the flexible package. Preferably, one part of the hook-and-loop strip(s) is/are adhered to inside bottom of the rigid package and the opposite part(s) is/are adhered to the outside bottom of the flexible package.

The strip(s) can be applied via an adhesive layer on the back of the hook-and-loop strip(s). Placing the filled flexible package into the rigid package will combine the two parts, thereby adhering the packages.

The disadvantage of this embodiment is, however, that one part of the strip(s) may stay attached to the rigid package, thereby reducing or complicating recycling possibilities.

The two parts of the hook-and-loop strip(s) should be applied to the flexible and the rigid package in such a pattern that a sufficiently large contact area between the two parts is ensured after insertion of the flexible package.

The particulate material

The particulate material preferably has the form of powder, granules, (mini)pearls, beads, flakes, or crystals, and can have any suitable shape. The particulate material is preferably free-flowing, meaning that it does not stick together to form lumps.

The paste

The paste according to the invention consists of a suspension of granular material in a fluid as the matrix to the granular material. The paste behaves as a solid until stress is applied, at which point it flows like a fluid. The paste exhibits this behaviour at room temperature.

The gel

According to the invention, the gel represents a viscoelastic fluid which does not behave as an ideal liquid. The gel exhibits this behaviour at room temperature.

Examples of compounds requiring GHS and/or CLP labelling are solid initiators and initiator formulations.

Other examples are materials that are added to polymers as antistatic, antislip, antifog, or anti-block agent. These materials are generally based on glycerol esters, ethoxylated amines, fatty amines, or fatty amides, often dispersed in a polymeric matrix.

Further examples are carbon black, flame retardants, fatty alcohol esters, and polymeric esters of long chain alcohols.

Examples of initiators are organic peroxides, azides, and C-C-initiators. Initiator formulations include initiators formulated on solid inorganic carriers and masterbatches of initiator dispersed in a polymeric matrix. Specific examples of solid initiators are dicumyl peroxide, di(tert- butylperoxyisopropyl)benzene, dicetyl peroxydicarbonate, dimyristyl peroxydicarbonate, dilauroyl peroxide, di(4-tert-butylcyclohexyl)peroxydicarbonate, didecanoyl peroxide, dibenzoyl peroxide, 2,2’-azobis(isobutyronitrile), 2,2’-azobis(2-methylbutyronitrile), 1 , 1’- azo(di(hexahydrobenzonitrile), and 2,3-dimethyl-2,3-diphenylbutane.

Examples of solid initiator formulations are formulations comprising (i) a solid or liquid organic peroxide, azide, or C-C-initiator and (ii) a solid phlegmatizer.

Examples of suitable phlegmatizers are solid inorganic carriers (e.g. calcium carbonate, silica, clay), polymer (e.g. polypropylene) matrices, and solid organic phlegmatizers (e.g. dicyclohexyl phthalate or glycerol tribenzoate).

Examples of organic peroxides that can be formulated with a solid phlegmatizers are dibenzoyl peroxide, di(4-methylbenzoyl)peroxide, 2,5-dimethyl-2,5-di(tert- butylperoxy)hexyne-3, 2,5-dimethyl-2,5-di(tert-butyl)hexane, tert-butyl cumyl peroxide, di(tert-butylperoxyisopropyl)benzene, dicumyl peroxide, butyl 4,4-di(tert- butylperoxy)valerate, 1 ,1 -di(tert-butylperoxy-3,3,5-trimethylcyclohexane, tert-butyl peroxybenzoate, di(4-tert-butylcyclohexyl)peroxydicarbonate, and 3,6,9-triethyl-3,6,9- trimethyl-1 ,4,7-triperoxanone.

The method

The flexible package is filled with particulate material, paste or gel and the filled flexible package is subsequently contacted with the adhering layer that is present on the inside of the rigid package, thereby contacting the outside - optionally containing the second component of a two-component adhesive or the opposite part of the hook-and-loop strip(s) - of the filled flexible package with the adhering layer, and thereby adhering the flexible package to the rigid package.

In a preferred embodiment, the adhering layer is present on the inside bottom of the rigid package, thereby contacting the bottom - optionally containing the second component of a two-component adhesive or the opposite part of the hook-and-loop strip(s) - of the filled flexible package with the adhering layer, and thereby adhering the bottom of the flexible package to the bottom of the rigid package. While filling, the flexible package may be outside the rigid package, or it may be (partly) inside the rigid package. If filled while being (partly) inside the rigid package, the weight increase caused by filling will cause the required pressure for adhering the flexible and the rigid package. It should, however, be ensured that the flexible and the rigid package do not adhere prior to filling.

After filling, the flexible package is closed, e.g. sealed or closed with a closing strip.

The rigid package containing the closed flexible package is closed, e.g. by folding flaps or placing a cover.

The outer wall(s) of the rigid package can be labelled with the required information concerning chemical content and safety. The label can be applied before, during, or after the method of the invention.

The following items are part of the invention:

Items:

1 . Method for packaging a particulate material, said method involving the steps of:

- providing a rigid package, having a bottom, a top, and a vertical wall, said rigid package being opened at the top and containing an adhering layer on at least part of the inside bottom or inside vertical wall,

- filling a flexible package with particulate material,

- contacting the filled flexible package with the adhering layer, thereby adhering the flexible package to the rigid package,

- closing the rigid package.

2. Method according to item 1 wherein the adhering layer is on at least part of the inside bottom of the rigid package.

3. Method according to item 1 or 2 wherein the adhering layer is a one-component adhesive.

4. Method according to item 2 wherein the adhering layer constitutes the first component of a two-component adhesive; the second component of said adhesive being present on the outside bottom of the bag. 5. Method according to item 2 wherein the adhering layer constitutes one part of at least one hook-and-loop strip adhered to the inside bottom of the box or drum; the opposite part of said at least one strip being adhered to the outside bottom of the bag.

6. Method according to any one of the preceding items wherein the rigid package is a box or drum, preferable made from cardboard or fibre board.

7. Method according to any one of the preceding items wherein the flexible package is a bag, preferably made of plastic.

8. Method according to any one of the preceding items wherein the particulate material is a chemical compound requiring GHS and/or CLP labelling.

9. Method according to item 8 wherein the chemical compound is an organic peroxide or organic peroxide formulation. 10. Method according to any one of the preceding items wherein the adhesive is a pressure sensitive adhesive (PSA).

1 1 . Method according to item 10 wherein the adhesive is a hot melt pressure sensitive adhesive (HMPSA).