HK1019058B - Labelled, returnable plastic crate - Google Patents

Description

Reusable plastic packing box with label

Background

The present invention relates to a reusable plastic container with at least one ink-only label and a method of applying an ink-only label to a polymeric surface.

More particularly, the present invention relates to a technique for marking reusable plastic containers, and more particularly, for applying labels to plastic containers for decorative promotional and/or informational purposes. More specifically, the present invention relates to a method of applying a technique of applying a composite label having only a pattern ink on a polymer substrate, a method of applying a label ink to a packaging box, a method of reinforcing the label ink by post-applying a film sealing ink in a post-treatment process, and finally removing the composite ink label without damaging the packaging box, that is, without performing destructive treatment on the surface of the substrate, thereby enabling re-labeling.

Currently, plastic packaging boxes are marked using one of three different methods. The most common method is to screen print a permanent pattern that is not removable before use by the end user. Such labels enhance the consumer grade of the packaged product by a highly durable decoration of two or three colors. However, this technique is of limited variety of colors, lacks the improved graphics that other labeling means can provide, does not have the flexibility to change graphics to meet market strategies resulting in a large inventory of out-of-date products, and shows wear marks only after four passes (tries) (the life expectancy of a typical package is 60 passes), and is therefore more expensive than other labeling means.

The second method involves applying a printed paper label to the plastic packaging box during the packaging and sealing. Such tags are almost impossible. However, it is hardly able to withstand label damage from handling and exposure to moisture, nor the necessary washing steps for reusable containers, requiring re-labeling.

The third, also recently developed, package marking technology is the application of pressure sensitive thin labels. This is a widely used method, but has a limited life cycle because it is difficult and expensive to remove when it is needed.

The need for reusable packaging containers is a direct result of government legislation in industry priority and in different parts of the world regarding the replacement of disposable packaging containers by reusable (refill) containers, and a completely new market for the disposal of packaged beverage containers has emerged in this recycling atmosphere. This is currently true for refillable PET and glass bottle containers. Some countries, especially in europe, have invested large amounts of money to create distribution systems that rely primarily on the concept of reusable packaging containers.

Obviously, in this recycling market, the only products present are those that can be printed on the outside of the box. Marketing, trademark, promotional, UPC codes or other information is printed on the exterior of the package for handling, space and storage. The reason is that in most cases, the boxes are stacked in a merchant, such as a grocery store, with only the side panels and end panels exposed. As such, what is present on the panels of the package is a feature that uniquely distinguishes one product from another.

When using a reusable package, it is attractive to use a uniform package for different products or brands. However, this is only possible if there is a convenient and inexpensive way of providing a pattern or mark on the package, which can be removed when the package is returned to the bottling line for refilling.

On the other hand, the labels, designs or markings on the packaging boxes must be durable, which is very important, especially during transport and storage; more importantly, it is durable even in humid conditions.

It is therefore an object of the present invention to provide a reusable plastic packaging container having on at least one surface thereof an ink only label which is durable, scratch resistant, abrasion resistant, weather resistant, moisture resistant when in use, but which is easily removed upon cleaning of the packaging container once returned to the factory.

It is another object of the present invention to provide a method of overprinting ink-only labels on polymeric surfaces such as plastic packaging boxes. The method is simple and cheap.

Summary of The Invention

These and other objects are achieved in accordance with the reusable plastic container package according to the invention.

That is to say, in one aspect, the present invention provides a reusable plastic packaging case provided on at least one surface thereof with an ink only label consisting of at least one ink only layer and an activatable adhesive layer, the label being removable from the surface without destructive treatment of said surface, said label being adhered to said at least one surface by activation of said activatable adhesive layer.

The term "ink only label" is used herein to define a graphic layer that does not have a paper or plastic support film, but that contains a layer of ink directly applied to a surface. The surface can also be seen at least partially, often through a patterned layer. By transferring the pattern with a reverse printed label, the label can be easily overprinted onto the surface with ink only.

The label used according to the invention must be based on an ink pattern without a support material. The ink pattern is adhered to the surface of the packing case by adhesive, and the surface of the pattern can be protected by a protective layer.

The present invention significantly improves upon prior art systems based on paper or plastic labels. To remove those labels, expensive high-pressure equipment must be used, especially in cases where labels are required on both adjacent sides of the package. It is simply not possible to remove the label by simple soaking, as in the present invention. Moreover, label residues tend to block packaging box cleaning equipment.

The system of the present invention is inexpensive and more environmentally friendly because the ink-only labels are easily removed from the soak solution and recycled.

The present invention also provides the possibility of label scanning, such as including a UPC code therein, to define the container, contents or any other useful information. The system also allows the manufacturer to reduce the inventory of packages because it is no longer necessary to stock all brands or types of packages. For the manufacturer, it is possible, according to the system of the invention, to use only one package for each raw material (e.g. bottle), regardless of the brand of the material. This makes it possible to save a lot of packing box stocks. Of course, if all industries in a country or continent decide to use the system, the savings would be even greater.

In this case, many different beverage container manufacturers (bottle manufacturers) use a common package, but still maintain the unique marketing characteristics through the present invention. At the same time, an improved user-friendly and cost-effective recycling system would be perfect. The system can be adopted by one country or even a plurality of countries.

According to a preferred embodiment, a transparent protective coating is applied over the ink only label. The coating increases the resistance of the label to environmental influences. The material of the protective coating is generally matched to the material of the ink. More preferably, all materials, adhesives, inks and protective coatings are acrylate polymers. To further increase the life of the label, it is preferred to treat the label (and coating) one or more additional times after it has been overprinted. These treatments provide coalescence (coalescence) between the layers of material, resulting in an extended service life without increasing the difficulty of cleaning.

The properties of the label, particularly with respect to the nature of the washed package, can be controlled by careful selection of the composition of the label, the use of the protective coating, and the post-treatment method. More specifically, a system can be devised that allows the label to be removed when the standard package is cleaned. This means that each time the beverage packaging plant is returned, the old label can be removed and a new, optionally different, label applied. On the other hand, the label can be made so durable that it is not removed or damaged during standard box washing unless special rigorous washing operations are employed. Thus, the label is non-permanent, but has all the advantages of permanent printing, such as screen printing, without its disadvantages, such as high investment cost, high energy requirements, poor flexibility, and few varieties of colors.

The choice of adhesive used in adhering the label design to the surface of the package will depend, at least in part, on whether the desired life of the label is one or more trips. Of course, the adhesive must be removable during cleaning of the package. The adhesive must be activated before or during the overprinting of the package. Conveniently and generally preferred, the pattern is applied by means of a heat-activatable adhesive which has been applied to the pattern by means of a reverse-printed label. Other methods include the use of adhesives that can be activated by radiation, chemical agents, electron beam, microwave, ultraviolet, and the like. The use of adhesives activated by photoinitiation of activation, wet activation, enzymatic activation, and pressure or sonication can also be used.

Preferably, an adhesive is used which can be activated by heat or pressure. The latter case also includes adhesives that are tacky when not under pressure but remain adhered when under pressure.

Preferably, the adhesive is present on the reverse side of the pattern before the pattern is applied to the surface of the package. However, it is also possible to apply adhesive to the packaging box before transferring the pattern. Another possibility is to use an ink in a pattern with an incorporated binder.

If a protective layer is used, it may be applied after the pattern has been transferred to the package, such as by a conventional roll coater. In another mode, the protective layer is a part of the material of the pattern when the pattern is transferred.

In another aspect, the present invention provides a method of printing an ink-only label on a polymeric surface, particularly a plastic container surface, said method comprising:

once the providing surface, preferably, moves at a constant speed,

an ink-only reverse printed label disposed on a substrate, the label comprising at least one ink-only layer and one activatable adhesive layer on a substrate, and being separated from the substrate and

the label ink is transferred to a polymer surface.

The label is preferably overprinted on a pre-treated and temperature stable polymer surface. Label overprinting is accomplished by transferring ink from a film substrate using a roller, rubber blade for painting, doctor blade, or air knife. Preferably, hot rolls are used under pressure. As previously described, the adhesive may be disposed on the label as well as on the polymer surface. The adhesive must be activated before or during transfer. The activation method differs depending on the kind of adhesive. The person skilled in the art knows which activation method is required. For pressure sensitive adhesives, pressure is applied during transfer. If a heat-activatable adhesive is used, the polymer surface is preferably preheated, optionally in conjunction with a thermal transfer system such as hot rolls.

In a preferred embodiment, the thermal pretreatment of the polymer surface is combined with a heat-activatable adhesive. When the heat activatable adhesive printed on the ink becomes tacky, the ink detaches from the film substrate and sticks to the plastic surface.

The label may be placed on a roll from which the pattern is transferred to the substrate, optionally in conjunction with a cutting operation. A stack of individual labels may also be prepared using suitable overlappings.

A protective film may be preferably used on the pattern according to pattern requirements. It can be applied as part of a countermark label when transferring a pattern. In a preferred embodiment, the protective coating is applied after the pattern has been transferred, such as by a roll coater.

In this case, the transfer surface is coated with a thin protective coating, such as acrylic wax, followed by a post-treatment, preferably one or more heat treatments. By doing so, the label material coalesces rather than adhering to the substrate, and it is believed that the permanent bond thus obtained is effected by interdiffusion of the adhesive and the plastic surface.

If a more durable pattern is desired, such as multiple passes, it may be preferable to use a more durable coating, such as polyurethane, and/or a more stringent post-treatment for a longer period of time.

Polymeric materials, particularly high density polyethylene, are known to be difficult to bond with adhesives. The invention describes a special method of surface treatment to ensure a fast and economical bonding with the adhesive.

An important discovery described herein is that the label material and surface coating coalesce by exposing the area to be marked to very high temperatures for a few seconds to increase durability and moisture resistance. This process changes the composite structure of the label from a series of adhesive layers that readily separate after immersion in water for two or more hours to a conglomerate of label adhesive, label ink and topcoat. During the heating process, the adhesive and the plastic surface diffuse into each other. In this preferred embodiment of the invention, the simultaneous internal diffusion and coalescence results in a very durable label. Its resistance to water soak ranges from hours to weeks based on different exposure times and final temperatures.

It must be noted that the water-soak resistance of the untreated label of the invention is sufficient, it never completely loses adhesion to the polymer surface. The adhesion is only weakened and the adhesion strength returns to the original value after drying.

After the desired durability of the label is achieved, it is also necessary to remove the label after the function of marking the container contents prior to consumption is completed. The empty plastic containers and beverage bottles are returned to the beverage plant for refilling. The plastic container is cleaned. Depending on the requirements (one or more roundtrips), the label must be completely removed or remain intact on the surface during the cleaning process.

In the former case, the heat-treated adhesive used to bond the ink substrate, while durable in water, is destroyed in the cleaning solution, preferably hot alkali enables complete removal of the label and adhesive. The label residue was filtered from the lye. In the latter case, the label is removed only when the washing conditions are changed to conditions for label removal, such as extended soak time and/or stronger lye, optionally together with high pressure jets (liquid or gas).

Other methods of removing the pattern without destructive treatment of the substrate (polymer) surface include chemical removal (solvent), ultrasonics, undercooling, heating, brushing, enzymatic treatment, vacuum treatment, stripping, and irradiation such as ultraviolet light. Various combinations of methods are of course also possible.

Processing equipment is required to mark the plastic containers on-line by the beverage machine during the normal procedure to match the package labels to the bottle contents.

Drawings

FIG. 1A schematic representation of a plastic container

FIG. 1B exploded view of a heat transfer label and substrate

FIG. 2A top view of a surface flame treatment and temperature stabilization process apparatus

FIG. 2B is a front view of a surface flame treatment and temperature stabilization process apparatus

FIG. 3A one embodiment of label application and ink transfer

FIG. 3B another embodiment of label application and ink transfer

FIG. 3C is a cross-sectional view of a heated blanket roll

FIG. 4A top view of a coating process

FIG. 4B overlay details of the applied coating

FIG. 5A top view of the post-flame treatment

FIG. 5B front view of post flame treatment

FIG. 6 embodiment of a Pattern transfer method

FIG. 7A shows the correlation between the moving speed of the packing container and the pressing force of the roller, wherein the temperature of the packing container is 93 deg.C, the temperature of the roller is 165 deg.C, and the hardness of the roller is 50 Shore A

FIG. 7B shows the correlation between the speed of the container moving and the temperature of the rollers, with a roller pressure of 5.5 bar, a container temperature of 93 ℃ and a roller hardness of 50 Shore A

Detailed description of the invention

Preferred embodiments of labels and coatings according to the present invention will first be described with reference to fig. 1A and 1B, which show a plastic container (1) and a label application location, respectively. The label may be applied to a film substrate (10), and the film substrate (10) may be any film, but in the case described herein is 2 mil thick polypropylene. (14) Is an acrylic coating that may or may not be coated depending on the source and type of substrate film available. (12) Is a release material covering the base film. In the case of the present invention, the silicone is applied when a film is produced. (20) Representing all overprinted ink materials. Depending on the label design and transparency requirements, the ink materials may be in up to five (5) different colors distributed in one or more layers that may be superimposed on each other. (30) And (40) represents two layers (2) of adhesive that accumulates 0.5 to 1.5 pounds per ream depending on the uniformity and rigidity of the marked surface of the container being marked.

During coating, all of the coating material is transferred from the silicone release coated substrate film. The body of the marking ink material is vinyl or acrylic based and is pigmented with a temperature and uv stable pigment. For white inks, titanium dioxide was chosen as the pigment. The pigment particle size is from 3 to 5 microns. The marking adhesive is a polyurethane modified polyacrylic acid with an initial tack temperature of 175F (80 c), which determines the temperature required on the plastic surface during transfer and is important to the plastic marking process. For certain labeled plastic containers, the inner surface is free of support and therefore, it is desirable to maintain the plastic below 200 ° F (93 ℃) to avoid distortion of the surface by reaching its point of deformation during label transfer.

The label imprinting method is described in process order. Fig. 2A and 2B show surface treatment and temperature stabilization techniques. Bonding two polymeric materials must take into account many factors such as cleanliness, pressure, temperature, contact time, surface roughness, movement during bonding, and adhesive film thickness. Another important factor is the critical surface tension. The common practice for measuring critical surface tension is to use the well-known Dyne solution (Dyne solution). For most adhesive applications, the critical surface tension of polyethylene is 31 dynes/cm. A series of tests have shown that treatment levels of 60 to 70 dynes per centimeter are necessary to take into account the strongest adhesion of the aforementioned adhesives to polyethylene surfaces. Further testing of commercially available equipment has shown that the flame treatment process optimizes the capital costs, operating costs and time required to achieve the required critical surfaces.

For adhesives that are quickly tacky and remain tacky, the polyethylene container must be heated before the label adhesive comes into contact with the polyethylene container. To avoid deformation of the container, it is desirable that the surface be heated to no more than 200 ° F (93 ℃). Since the surface temperature left for flame treatment is about 125F (52 c), the surface must also be heated to about 75F (24 c). There are still many heating methods available. Hot air, additional fired heaters, gas fired infrared panels and electric ceramic panels were tested and found to either heat too slowly or be difficult to control. It has also been found that a quartz melt-spun disk with an area control heater for positioning the label transfer machine provides free air conduction of the infrared energy maximum without affecting the surrounding environment. The most effective wavelength (2.5 to 3.2 microns) for peak absorption of infrared energy is emitted with polyethylene having an emissivity of 0.9 at temperatures between 1650 ° F (900 ℃) and 1725F (940 ℃). The test unit was rated at 60 watts per flat inch. For the desired 75 ° F (24 ℃), the time to heat the polyethylene surface from a position 2.5 cm from the emitting dish was 4.5 seconds.

Fig. 3A and 3B illustrate a label coating process by which a printed ink material is transferred from a polypropylene film substrate to a polyethylene surface using the tactile properties of a heat-activatable adhesive to overcome the adhesion of the ink layer 14 to the corona treated silicone coating 12. Factors that affect transfer are contact time, temperature at contact and film tension at contact, especially tension on the film after ink detachment. The diameter of the pressure roller is also a factor but not a variable. For the method of the present application, the diameter of the roller is 38 mm. The roller is made of silicone rubber with a steel core in the middle and a rubber hardness ranging from shore a50 to 80. It should be noted that at higher hardness, the rubber roller is deformed (flattened) less, so that the contact area can be smaller and the transfer pressure greater. This is important when the line speed is high and the contact time is low. Thus, when a package is passed at a rate of 18.3 meters per minute (60 feet per minute) over a 38 millimeter diameter roller, the roller is not deformed for a contact time of 1 millisecond per 1℃ roll.

The roller pressure is provided by a cylinder activated by a conventional solenoid valve, which is controlled in turn by two adjacent switches, one to advance the roller and the other to retract it. Other methods, such as mechanical attachment, are apparent and are not described in detail herein. The pressure is distributed over the entire cylinder length, from 12 kg to 17 kg being transferred per cm of roller length for this particular ink. See fig. 7A.

Thus, the present invention relies on the heat activatable adhesive adhering to the surface of the high energy package to advance the film at precisely the same rate as the package passes through the roller. The freely rotatable pressure roller maintains the same tangential velocity as the film and package. So that the ink is completely transferred without deformation.

For rapid and thorough bonding, the pressure roller is moulded onto a hollow core, between which a heating resistor operated by a controller is suspended. A 500 watt heating element to maintain the roll surface at any predetermined temperature. For purposes of the present invention, the roll surface temperature is between 250 ° F and 370 ° F (120 ℃ and 190 ℃). See fig. 7B.

Many silicone coated polymer films are useful as printing substrates. High temperature films such as polyester may be in continuous contact with the hot rolls. Low temperature films, such as polypropylene, must be prevented from contacting the hot rolls during the marking operation. For this reason, a film guide is used to support the film as the roller is retracted. The guide was mounted, maintaining approximately 13mm between the guide and the marking surface. At the same time, the roller is set back by about 13mm behind the film. By maintaining this gap, e.g. pulling and twisting of the polypropylene film is avoided. The high temperature film does not require a guide.

It has been found that film tension, particularly the end of the film that exits the roller, is critical to completing the ink transfer. Through experimentation, a sustained tension of about 2.5 kilograms was found to be very useful. This can be achieved by spring loaded tension auto-adjustment (spring loaded dancer arm) and rollers.

Conventional nip rollers and stepper motors are used to advance the film to the next label and to be accurately positioned by initiating an optical scanning device with the printed indicia.

This is also achieved by applying an aqueous emulsion of an acrylic-based wax, as shown in FIGS. 4A and 4B, for the purpose of protecting the ink from inadvertent scratching during handling, and for the purpose of increasing the resistance to weathering during outdoor storage. This can be applied by a roll coater equipped with a wet roll with a controlled amount of coating. Can be controlled by the doctor blade. The coating spreads well, over the edges of the ink pattern and seals against moisture ingress.

The final processing step is to coalesce the coating film, label ink and adhesive together and to interdiffuse the adhesive layer and polyethylene matrix as shown in fig. 5A and 5B. This was found by extensive testing of a variety of heating systems. Since flame treatment was found to be the best technique for providing the surface energy required for label adhesion, flame treatment of labels and composite films was found to be the best technique for extending the required water soak durability without sacrificing the mechanical properties of the overlaminate or changing its appearance characteristics, or distorting the polypropylene package.

The best mode for overprinting of the present invention currently under development is shown in FIG. 6.

It is to be understood that further modifications can be made to the above disclosed embodiments while still obtaining many advantages without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims (17)

1. A reusable plastic packaging case provided on at least one surface thereof with an ink only label consisting of at least one ink only layer and an activatable adhesive layer, the label being removable from the surface without destructive treatment of said surface, said label being adhered to said at least one surface by activation of said activatable adhesive layer.

2. The package of claim 1 wherein a transparent protective coating is applied over said ink layer.

3. A packaging case according to claim 1 or 2 wherein the adhesive layer is heat activatable.

4. A packaging case according to claim 1 or 2, wherein the adhesive layer loses adhesion when treated with an aqueous alkali solution.

5. A container as claimed in claim 1 or claim 2, wherein at least a portion of the surface is formed of polyethylene.

6. A package according to claim 1 or 2, wherein the ink only label comprises a layer of coalesced adhesive and a layer of ink only graphics and optionally a protective layer.

7. A package according to claim 1 or 2, wherein the ink is a polymer ink, preferably an ethylene or acrylic based ink.

8. A packaging case according to claim 1 or 2 wherein the adhesive is a heat activatable adhesive having an initial tack temperature of up to 90 ℃.

9. The package of claim 8, wherein the adhesive is a polyurethane-acrylic adhesive.

10. A package according to claim 1 or 2, wherein the protective coating is based on an acrylic wax.

11. A method of applying an ink-only label to a polymeric surface, said method comprising:

-providing a surface, preferably moving at a constant speed,

-applying to the substrate a reverse printed ink-only label consisting of at least one ink-only layer and one activatable adhesive layer on a substrate, separate from the substrate, and

-transferring the label ink to a polymer surface.

12. The method of claim 11, wherein the surface of the polymer has been activated prior to placing the reverse printed label.

13. The method of claim 12, wherein the activation is a flame treatment.

14. A method according to any one of claims 11 to 13 wherein the adhesive is heat activatable and the surface is heated prior to application of the reverse printed label.

15. A method according to any one of claims 11 to 13, wherein the transferred label is covered by a transparent, protective coating.

16. A method according to any one of claims 11 to 13, wherein the surface, optionally together with the protective coating, has been subjected to one or more heat treatments to coalesce the applied material.

17. A method according to any one of claims 11 to 13 for manufacturing a package according to any one of claims 1 to 10.