WO2007065508A2

WO2007065508A2 - Multi-layer container

Info

Publication number: WO2007065508A2
Application number: PCT/EP2006/010527
Authority: WO
Inventors: Frank Zeiter
Original assignee: Kpss-Kao Professional Salon Services Gmbh
Priority date: 2005-12-07
Filing date: 2006-11-02
Publication date: 2007-06-14
Also published as: DE102005058422A1; WO2007065508A3

Abstract

A container with a body comprising at least two layers, wherein a first layer is formed as an inner layer (11) and a second layer as an outer layer (12). The outer layer of the container is transparent and comprises effect pigments (20).

Description

MuIti-layer Container

Field of the Invention

The invention relates to a container, preferably a bottle with a multi-layer construction, and in particular a

container with at least two layers, wherein the outer layer of the two layers is transparent and comprises effect

pigments . The invention further relates to a method for producing a container of this kind.

Prior art

Known from the prior art are plastic bottles, for example for cosmetics or detergents, made of different materials.

Frequently, the bottles are made of one single type of material only, wherein these bottles can comprise

monomaterial with either hiding or translucent pigments.

Also known from the prior art are multi-layer bottles. The production of these multi-layer bottles can take place in different ways. For example, the bottles with a multi-layer design may be produced by extrusion blow moulding. With this process, a molten preform is extruded into a mould and inflated with compressed air. The blow moulding can be performed with batches of different colours. The plastic bottles produced by this process are generally translucent or opaque, with more or fewer effect pigments, such as, for example, pearl effect pigments, absorption pigments or metal effect pigments.

Another process for producing multi-layer bottles is the so- called coextrusion process. With this process, identical or different plastic melts are combined before leaving the extruder's profile die. This method is used to produce plastic bottles made of multi-layer composite materials, which, for example, comprise different material combinations. Bottles made of coextruded composites, for example, are known comprising coextruded materials with hiding pigments with special barrier layers. For example, a layer made of ethylene vinyl alcohol (EVOH) can be used as a barrier layer. The EVOH layer acts as a barrier to gasses and any other kinds of penetrating substances. Also known are plastic bottles, which inside have an opaque coloured coextruded material with hiding pigments with no effect and on the outside of which is arranged either an opaque coextruded material with gloss pigments, such as, for example, mother of pearl, or a

transparent gloss layer.

The use of pigments is generally used to determine the colour direction or nuance and appearance. In principle, a

distinction is made between three types of pigments:

absorption pigments, metal effect pigments and pearl effect pigments. Figure 1 is a schematic diagram showing how the different types of pigment can influence the further

directional course of incident light rays. As Fig 1 shows, the different pigments 20 are each embedded in a layer 10. The course of the light rays is designated 30.

The absorption pigments absorb part of the incident white light while reflecting back the other part in a diffusely distributed way (see Fig Ia) . The diffusely reflected part of the incident light is perceived by the viewer as the colour in question. Metal effect pigments are generally aluminium flakes which, when embedded in transparent binders, reflect the incident light in the regular manner, i.e. the angle of incidence is equal to the angle of emergence (see Fig Ib) .

Pearl effect pigments, on the other hand, are pigment flakes made of a transparent material, such as, for example mica flakes coated with titanium oxide or iron oxide. Mica is a mineral group belonging to the sheet silicates. Due to the transparency of the pigment flakes, these provide much higher reflection of the light than the opaque aluminium flakes. As Fig Ic shows, the light rays with the pearl effect pigments are greatly scattered and reflected not only by the surface of the pigment, as is the case with the above-described metallic pigments . Parts of the incident light are reflected directly as they arrive on the coating while other parts of the incident light penetrate the pigment flakes and on emerging from the pigment flakes in question are reflected again.

Depending upon the viewing angle and determined by the interference, the pearl effect pigments bring about a change in the colour perceived by the viewer. Fig 2 shows the influence of the thickness of a layer 10, for example a titanium dioxide layer, on the resulting interference colour 50a. As Fig 2 shows, the colours of the interference pigments change from white 50a with a layer thickness of 40-60 run, through yellow 50b with layer thicknesses of 60-80 nm, red 50c with layer thicknesses of 80-100 nm, right up to bluish tones 5Od with layer thicknesses of 100-140 nm and finally green 5Oe with a layer thickness of 120-160 nm.

The particle size of the pearlescent pigments also has an influence on the colour result later perceived by the viewer, as shown in Fig 3. In particular, Fig 3a-b show several pigments 20 of different sizes, each embedded in a layer 10. The path of incident light rays 30 is indicated by arrows. As Fig 3 shows pearlescent pigments with larger particle sizes, in particular larger than 100 μm, are responsible on the one hand for a high gloss or sparkling effect. On the other hand, however, large particles have a poorer hiding power and result in a lower degree of light scattering than smaller particles. Very small particles, for example between 5 and 20 μm, give the viewer the impression of a silk finish effect, have a good hiding power, and result in extreme scattering of the incident light. Usually, particle sizes of between 40 and 60 um are used which still have a significant gloss effect but, in additional to distinct light scattering, still have a satisfactory hiding power.

In order to achieve specific optical surface effects, plastic containers are also frequently coated with banderoles. In particular, metallised foils are used to achieve special effects, such as, for example, a pronounced metallic effect. The metallic effect gives the viewer the impression of a glossy metallic surface. In addition, plastic containers are frequently painted in order to modify the optical appearance of the surface. Here, different layers and high-gloss finish paints can be used to modify the properties of the container with regard to both the appearance and the feel.

However, with the containers known to date from the prior art, it was only possible to produce either a container with a high colour brilliance or a container with a high degree of optical depth. The optical depth characterises the light transmission or the transmissivity of a layer. If a layer has poor transmission properties, the light is 'absorbed' by the layer. In order, however to satisfy the growing consumer demands with regard to optically attractive embodiments of containers, it was, therefore, desirable, to produce a container with high colour brilliance and simultaneously excellent optical depth.

Description of the Invention

The invention is therefore based on the object of providing a container, such as, for example, a bottle, with a brilliant colour and excellent optical depth.

This object is achieved by a multi-layer container with the features of the claim 1. According to the invention, a container is produced with a body comprising at least two layers, wherein a first layer is formed as an inner layer and a second layer as an outer layer. The container is characterised in that the outer layer is transparent and comprises effect pigments. The provision according to the invention of the effect pigments in the transparent outer layer creates a container, which for the viewer has both a brilliant colour and excellent optical depth .

Advantageous embodiments are characterised by the dependent claims .

Advantageously, the effect pigments are selected from the group comprising absorption pigments, metal effect pigments and pearlescent pigments. This has the advantage that, due to the different properties of the type of pigment in question, it is also possible to achieve very different optical or tactile properties of the container surface. In particular, absorption pigments are used to influence the colour

direction. Metallic pigments are used to achieve a metallic gloss and pearl effect pigments to achieve a mother-of-pearl- type effect.

According to a particularly preferred embodiment, the pearl effect pigments are micas coated with titanium (di) oxide. Preferably, natural mica is used. Due to their flake-like shape, micas have the advantage that they can be easily coated with a uniform thickness. Preferred for coating the micas are in particular titanium oxide, with a layer

thickness of approximately 80 to 100 run. This layer thickness achieves the interference colour red, whereby, due to the embedding of the micas in the transparent outer layer, a particularly intensive glossy red shade is achieved.

Normally, the coating on the micas is of approximately the same thickness on both sides. The micas as such are in turn generally of a thickness similar to the thickness of the coating on one side. Longer micas or micas with a larger diameter are used to achieve a greater sparkling effect. In addition to coating the micas with titanium oxide, coating with other materials is also considered, such as, for example iron oxide.

In a preferred embodiment, the inner layer is bonded to the outer layer by means of a bonding agent (BA) . Different bonding agents are used depending upon the material . Examples of bonding agents are OREVAC^® from ATOFINA, Puteaux, France or ADMER^® from MITSUI CHEMICALS AMERICA INC., Rye Brook, N.Y., USA. In addition, different material combinations are

considered for the inner and outer layers of the container according to the invention. It is in particular preferable for the layer construction comprising inner layer/bonding agent (BA) /outer layer is selected from the group consisting of polypropylene (PP) /BA/PETG, polypropylene

(PP) /BA/polyamide (PA), polyethylene (PE) /BA/polyamide (PA), polyethylene (PE) /BA/PETG and polyethylene

(PE) /BA/polypropylene (PP). The choice of the different plastics and their combination with each other enables containers to be endowed with different physical, chemical and mechanical properties. For example, the material

combination PP/BA/PETG is used to achieve containers with a high degree of gloss and high rigidity. The high depth penetration-gloss of this material combination is due to the low refractive index. In addition, to achieve a high gloss, the walls of the mould used to produce the container are polished. If glossy containers with a lower rigidity are required, a material combination of PE/BA/PA is used, for example. With this material combination, the resulting container has less gloss than the first-mentioned material combination, since PA is not transparent. A combination of PE/BA/PP, on the other hand, results in a relatively elastic material . Containers produced from this last-mentioned material combination are, therefore, relatively elastic, but have less gloss than containers produced from the previously- mentioned material combinations. With all these material combinations, it is possible to use the desired type of pigment, preferably pearl effect pigments, in a transparent matrix as an outer layer. This makes it possible to use different materials or material combinations, which can each be selected for the desired purpose, to produce a highly brilliant gloss container with excellent optical depth.

In a particularly preferred embodiment, both the inner layer and the outer layer are produced from PETG. The advantage of these embodiments is that no bonding agent is required to bond two layers of the same type, i.e. there is a complete bonding of the layers even without bonding agents. In the case of combinations of different materials on the other hand, it is necessary to use a bonding agent. If the bonding agent, which is intended to bond two different types of material, does not achieve this to a degree of one hundred percent, delamination could occur. In the case of

delamination, which is caused in particular by higher

temperatures, the layers previously bonded by the bonding agent separate. Normally, delamination is observed within one to seven days at a temperature of 40 ⁰C. The use of identical base materials for the different layers can prevent the problem of the occurrence of delamination.

In another preferred embodiment, in addition to the inner layer and the outer layer, another layer is provided

optionally. This third layer is provided as the outermost layer and arranged as a covering layer on the outer layer . The third layer can also be used to modify the surface properties of the container material. These modifications may relate to both the appearance and the feel. For example, the optional third layer can further improve the colour

brilliance, while the optical depth is retained virtually completely. Advantageously, all the layers, i.e. the inner layer, the outer layer and the covering layer, are made of PETG. The use of materials of the same type means that it is possible to dispense with a bonding agent and consequentially the

potential risk of the occurrence of delamination is avoided. In a particularly preferred embodiment, the inner layer is made of opaque red PETG and the outer layer is made of transparent PETG, wherein the effect pigments, particularly preferably pearl effect pigments, are embedded in this outer layer. The outer layer is also covered by a covering layer, which forms the outermost layer of this three-ply layer construction. The covering layer is advantageously made of crystal-clear PETG, i.e. without any further effect pigments. This further intensifies the optical effects, e.g. the gloss effect and the excellent optical depth, created by the other two layers .

Preferably, the concentration of the pigments used, i.e. the percentage content of the pigments based on the whole

composition of the layer in question, is approximately 4 percent by weight in the preferably opaque inner layer. The concentration of the effect pigments in the transparent outer layer is preferably 4 to 8 percent by weight. If a third layer, i.e. the covering layer, is additionally provided, in a preferred embodiment, this is colourless and consequently does not have any pigments.

The thicknesses of the individual layers, which in their entirety form the wall thickness of the container, can be different. Preferably, the thickness of the inner layer is 60 to 85%, in particular 70 to 85%, and particularly preferably 70 to 80% of the overall thickness of the container wall. The thickness of the outer layer is preferably 5 to 20%, in particular 7.5 to 15%, and particularly preferably 7.5 to 10% of the overall thickness of the container wall. The same applies to the covering layer, whose thickness is preferably 5 to 20%, in particular 7.5 to 15%, and particularly preferably 7.5 to 10% of the overall thickness of the

container wall.

In a preferred embodiment, the container according to

invention is a bottle. In particular, the use of the

container, or the bottle, to hold cosmetic products, such as, for example, hair care products, is considered.

Preferably, the above-described container is produced by a coextrusion process. The advantage of this process is that that both identical and different materials, if desired also in different colours, may be used together in a single production step for producing the container.

Brief description of the drawings

The following describes the invention purely by way of example with reference to the attached drawings, which show:

Figs la-c different types of pigments

Fig 2 the influence of the titanium dioxide layer thickness on the interference colour formed

Figs 3a-b the effect of different particle sizes on the colour result

Fig 4 a first preferred embodiment of a container according to the invention

Fig 5 a detail view of the embodiment shown in Fig 4, and

Fig 6 a second preferred embodiment of a container according to the invention.

Ways of carrying out the invention

Fig 4 shows a first preferred embodiment of the layer

construction of a container according to the invention.

Generally, the container or the container wall comprises two layers 11, 12, bonded by means of a bonding agent 15. As Fig 4 shows, the outer layer 12 is thinner than the inner layer 11. In a particularly preferred embodiment, the overall thickness of the container wall is 0.8 mm, wherein the inner layer 11 is 0.48 mm thick, the bonding agent 15 is 0.12 mm thick and the outer layer 12 is 0.2 mm thick. In this

preferred embodiment, the thickness ratio inner layer/bonding agent/outer layer is 60%/15%/25%. Generally, the thickness of the inner layer can be between 60 to 85%, and the thickness of the outer layer between 5 and 20% of the overall thickness of the container wall. The thickness of the bonding agent 15 is normally between 5 and 20 % of the overall thickness of the container wall.

In the preferred embodiment of the container according to the invention shown in Fig 4, the inner layer 11 is made of PP, and the outer layer 12 of PETG. The bonding agent 15 used can be for example ADMER® from MITSUI CHEMICALS AMERICA INC., Rye Brook, N.Y. , USA. A detail view of the embodiment shown in Fig 4 is shown in Fig 5. In particular, this shows the detailed structure of the outer layer 12, wherein effect pigments 20 are embedded in the outer layer 12. With this particularly preferred embodiment, micas coated with titanium oxide are embedded as effect pigments 20 in a transparent PETG outer layer 12. Preferably, the micas have an 80-100 nm thick titanium oxide layer which causes the incident light to be reflected with a red glimmer. The path of the incident light rays is designated 30. As Fig 5 shows, parts of the incident light are reflected when they fall upon the micas, while other parts of the light first penetrate the micas and are reflected again when they emerge. Depending upon the viewing angle and determined by interference, the effect pigments result in a changing, pearl-of-mother-like, colour result. A container with the structure described above has high-brilliance gloss with an excellent optical depth.

Fig 6 shows a second preferred embodiment of the container according to the invention. In this embodiment, the container wall is constructed of three layers, the inner layer 11, the outer layer 12 and a covering layer 13. In the embodiment shown in Fig 6, the outer layer 12 and the covering layer 13 have approximately the same thickness, while the inner layer 11 is thicker than the other two layers. However, it is also possible for the outer layer 12 and the covering layer 13 to have different layer thicknesses. In a preferred embodiment, the covering layer 13 is thicker than the outer layer 12. In general, the inner layer 11 can be between 60 and 85%, the outer layer 12 between 5 and 200, and the covering layer 13 between 5 and 20% of the overall thickness of the container wall .

In a particularly preferred embodiment, the inner layer 11 is made of opaque red PETG, the outer layer 12 of PETG with pearlescent pigments and the covering layer 13 of transparent PETG. If the same materials are used for all three layers 11, 12, 13, it is possible to dispense with the use of a bonding agent. It is also possible to exclude delamination since the complete bonding of the layers 11, 12, 13 is guaranteed, even without bonding agents, due to the use of the same materials. A container with the above-described layer construction has a high-brilliance gloss and simultaneously has excellent optical depth.

Claims

1. Container with a body comprising at least two layers, wherein a first layer is formed as an inner layer (11) and a second layer as an outer layer (12);

characterised in that

the outer layer is transparent and comprises effect pigments (20) .

2. Container according to claim 1, wherein the effect

pigments (20) are selected from the group consisting of absorption pigments, metallic effect pigments, and pearl effect pigments.

3. Container according to claim 2, wherein the pearl effect pigments are micas coated with titanium dioxide.

4. Container according to any one of the preceding claims, wherein the inner layer (11) is bonded to the outer layer (12) by means of a bonding agent (15) .

5. Container according to claim 4, wherein the layer

construction of inner layer/BA/outer layer is selected from the group consisting of PP/BA/PETG, PP/BA/PA, PE/BA/PA, PE/BA/PETG and PE/BA/PP.

6. Container according to any one of claims 1 to 3 , wherein the inner layer (11) and the outer layer (12) are made of PETG.

7. Container according to any one of claims 1 to 3 , wherein the inner layer (11) and the outer layer (12) are made of PP.

8. Container according to any one of the preceding claims, comprising a third layer, wherein the third layer is arranged as a covering layer (13) on the outer layer (12) .

9. Container according to claim 8, wherein the inner layer (11), the outer layer (12) and the covering layer (13) are made of PETG.

10. Container according to any one of the preceding claims, characterised in that the container is a bottle.

11. Use of a container according to any one of claims 1 to 10, for containing cosmetic products.

12. Method for producing a container according to any one of claims 1 to 10, characterised in that the process is a coextrusion process.