DE102010036029A1 - Process for treating preforms for the manufacture of containers by blow molding and for printing such containers - Google Patents

Abstract

Process for the treatment of preforms made of plastic, preferably made of PET for the production of containers by blow molding.

Description

The invention relates to a method according to the preamble of claim 1 or 9.

For the purposes of the invention, "containers" are in particular cans, bottles, tubes, pouches made of metal, glass and / or plastic, but also other packaging materials which are suitable for filling liquid or viscous products for pressure filling or for pressureless filling.

For the purposes of the invention, "printing" generally means the application of one or more printed images or imprints, in particular also multicolored printed images or imprints on the respective container outer surface, regardless of special printing processes. Printing is preferably carried out using printing heads known to the person skilled in the art and working according to the inkjet method, which are also known in the art DE 10 2006 001 223 A1 are described. The printing inks or printing inks are each applied as fine droplets next to one another and also partially overlapping, so that the overall result is a multicolor print image, after drying or curing of the printing inks in the form of a color or print layer formed by the print image or print. For printing the container z. As printing inks used, which are dried or cured by energy input, ie by heat and / or UV radiation and / or microwave radiation and / or beta radiation, preferably by crosslinking.

The production of containers made of plastic, in particular PET using preforms or preforms by stretch or blow molding is known. It is also known to directly print such container of the outer surface of its container wall, even digitally with working according to the inkjet printheads.

The object of the invention is to provide a method which allows a direct printing of plastic containers produced by stretch or blow molding, in particular of PET containers in an optimal manner and with improved adhesion of the imprint or the printing inks used on the respective container. To solve this problem, a method according to claim 1 is formed. A method for printing, in particular for digital printing of plastic containers is the subject of claim 9.

In the invention, the printing takes place on an intermediate or adhesive layer which is applied to the preforms used in this case before the blow molding of the containers. As a result, on the one hand there is the possibility that the printing and in particular the digital printing of the container on the intermediate or adhesive layer can take place immediately after the blow molding of the container. Furthermore, it is advantageously possible that the preforming or heating of the preforms required for blow molding can also be used at the same time for drying and / or crosslinking and / or predrying or partial crosslinking and / or during the production of the intermediate or adhesive layer. The respective intermediate or adhesive layer forming material or the corresponding material layer is preferably applied to the preforms prior to their transfer to a preform furnace, in which then takes place with the heating or preheating of the preforms and the drying of the respective intermediate and adhesive layer , or when using a hot melt or hotmelt-like material for the intermediate or adhesive layer of this material is applied in the preform oven or at a local preheating on the preforms.

Further developments, advantages and applications of the invention will become apparent from the following description of exemplary embodiments and from the figures. In this case, all described and / or illustrated features alone or in any combination are fundamentally the subject of the invention, regardless of their summary in the claims or their dependency. Also, the content of the claims is made an integral part of the description.

The invention will be explained in more detail below with reference to the figures of exemplary embodiments. Show it:

1 in simplified schematic representation and in plan view of a plant for producing containers in the form of bottles (PET bottles) by blow molding and for subsequent printing of the bottles;

2 in detail a holding and centering element with a preform;

3 in a simplified representation, a treatment station for applying an intermediate or adhesive layer-forming material to the preforms moved past this treatment station;

4 in each case a side view of a preform and a bottle produced therefrom by stretch or blow molding;

5 a section through a container or bottle wall in the region of an imprint;

6 in a simplified representation of a further embodiment of the treatment station for applying an intermediate or adhesive layer on the moving past at this treatment station preforms.

In the figures is 1 a plant for the production of bottles 2 from plastic (PET bottles) by blow molding using preforms or preforms 3 , These are in the plant 1 over a conveyor line 4 supplied and get from this conveyor line 4 one at a time on a transport star 5 standing by holding and centering element 6 at which the preform 3 by clamping on its open downward and the later bottle opening 2.1 forming open end 3.1 clamped and centered.

With its holding and centering element 6 become the preforms 3 each at a treatment station 7 ( 3 ) led by the transport star 5 is provided and in which the preforms 3 on the outer surface of her section 3.2 , the later bottle body 2.2 forms, with an intermediate or adhesive layer 8th be provided in the 5 is shown with exaggerated layer thickness. The application of the intermediate or adhesive layer 8th forming material, which is for example a plastic material, takes place in the in the 3 illustrated embodiment of the treatment position 7 by means of a spraying device 9 with nozzles 9.1 by spraying on the area 3.2 , namely at about the longitudinal axis with the holding and centering element 6 turned preform 3 ,

The way with the intermediate or adhesive layer 8th provided preforms 3 then continue to arrive at the respective holding and centering 6 kept in a preheating section 10 in which the preforms 3 heated to a temperature required for blow molding and this at the same time also the intermediate or adhesive layer 8th or the material forming this layer is dried or crosslinked by the action of heat. The in the preheating section 10 preheated and with the intermediate or adhesive layer 8th provided preforms 3 are then together with their holding and centering 6 via another transport star 11 each to a blow mold 12 passed on the circumference of a rotatable around a vertical machine axis rotor 13 a blow molding machine 14 are provided. On the angular range of rotation of the rotor 13 between the transport star 11 and another, the outlet of the blowing machine 14 forming transport star 15 the blow molding of the bottles takes place 2 from the respective preform 3 under stretching of the section 3.2 as well as the applied intermediate and adhesive layer 8th ,

On a in transport direction to the transport star 15 subsequent and in the 1 generally with 16 designated treatment path is inter alia a printing of the respective bottle 2 on the intermediate or adhesive layer 8th so that then in the 5 schematically shows layer sequence, consisting of the wall 2.3 the respective bottle 2 , From the applied on the outer surface of this wall intermediate or adhesive layer 8th and from a printing layer formed by the respective imprint, preferably multicolored imprint 17 ,

The intermediate or adhesive layer 8th is primarily used to provide optimum adhesion to the print 17 or for the corresponding inks or printing inks to achieve and / or for printing a surface to ensure optimum wetting with the inks used. With the intermediate or adhesive layer 8th will be the adhesive strength of the imprint 17 determining surface tension of the respective bottle 2 increased in the area to be printed, for example, to a value greater than 42 mN / m.

Reachable values are from 45 mN / m to over 50 mN / m, depending on the printing ink used.

That for the intermediate or adhesive layer 8th The material used is, for example, one which dries with heat, for example, a heat-crosslinking material or a solvent-based material which, for example, uses water as a solvent and cures by evaporation of this solvent.

By appropriate choice of the material of the intermediate and adhesive layer 8th If other properties can also be achieved, it is possible, for example, for the intermediate or adhesive layer 8th be executed so that they have an additional barrier layer on the outer surface of each bottle 2 forms, namely to improve the barrier properties of the bottle 2 by at least 10%, in particular also with respect to gases, such as CO 2 and / or O 2, but also a migration of constituents of the printing inks or printing inks used in printing into the interior of the respective bottle 2 prevented.

To improve the adhesion, this can be done for the intermediate or adhesive layer 8th The material used also contains nanoparticles, such as nanofibers or nanotubes, resulting in improved adhesion of the imprint 17 a defined roughness is generated on the surface to be printed.

• – dass die Haftfestigkeit oder Haftungsraten zwischen der Zwischen- oder Haftschicht 8 und der Behälterwandung 2.3 größer ist als die Haftfestigkeit oder Haftungsraten zwischen der Zwischen- oder Haftschicht 8 und der Druckschicht 17, wobei die Haftung innerhalb der Druckschicht 17 höher ist als die Adhäsion dieser Schicht auf der Zwischen- oder Haftschicht 8, oder
• – dass die Haftfestigkeit oder Haftungsraten zwischen der Zwischen- oder Haftschicht 8 und der Druckschicht 17 größer ist als die Haftfestigkeit oder Haftungsraten zwischen der Zwischen- oder Haftschicht 8 und der Behälterwandung 2.3, wobei die Haftung zumindest innerhalb der Zwischen- oder Haftschicht 8 höher ist als die Adhäsion dieser Schicht auf der der Behälterwandung 2.3.

Furthermore, it can be achieved that during a recycling process of the bottles 2 of the respective imprint 17 or the pressure layer formed by this as easily as possible on the respective bottle 2 remaining and in this case preferably transparent intermediate or adhesive layer 8th or the intermediate or adhesive layer 8th together with the imprint 17 from the respective bottle 2 can be easily replaced. For this purpose, the respective imprint or the print layer 17 and the intermediate or adhesive layer 8th set by choice of material and / or by the type of drying and / or crosslinking, for example,

• - That the adhesion or adhesion rates between the intermediate or adhesive layer 8th and the container wall 2.3 greater than the adhesion or adhesion rates between the intermediate or adhesive layer 8th and the print layer 17 , wherein the adhesion within the printing layer 17 is higher than the adhesion of this layer to the intermediate or adhesive layer 8th , or
• - That the adhesion or adhesion rates between the intermediate or adhesive layer 8th and the print layer 17 greater than the adhesion or adhesion rates between the intermediate or adhesive layer 8th and the container wall 2.3 wherein the adhesion is at least within the intermediate or adhesive layer 8th is higher than the adhesion of this layer on the container wall 2.3 ,

In any case, the material is for the intermediate or adhesive layer 8th but chosen so that these are before the blow molding of the bottles 2 on the preforms 3 applied and dried or cured intermediate or adhesive layer 8th with the respective section 3.2 can be stretched during blow molding without causing cracks in the intermediate or adhesive layer 8th or to a detachment of this layer from the bottle wall 2.3 comes.

By the described training of the treatment station 7 is the coating of the preforms 3 with the intermediate or adhesive layer 8th forming material format-independent, ie without a conversion can preforms 3 different size, ie different length and / or thickness for the production of bottles 2 or other containers of different size and / or shape coated or with the intermediate or adhesive layer 8th can be provided.

The 6 shows as a further embodiment, a treatment station 7a extending from the treatment station 7 characterized in that the application of the intermediate or adhesive layer 8th or the material forming this layer, not by means of a spraying device, but by using a roller 18 takes place, via an applicator, not shown on its roll surface with the intermediate or adhesive layer 8th forming material is provided and at which the respective preform 3 with the circular cylindrical or substantially circular cylindrical outer or outer surface of its section 3.2 rolls.

Above, it was assumed that the intermediate or adhesive layer 8th before the transfer of the preforms 3 to the blowing machine 14 or to the local blow molds 12 cured or substantially cured, ie in particular dried and / or crosslinked, for example by the action of heat on the preheating 10 (Preform furnace). By drying or crosslinking the intermediate or adhesive layer 8th within the heating or preheating section 10 (Preform oven) is basically no additional drying module needed.

There is also the possibility of the intermediate or adhesive layer 8th on the preheating line 10 merely pre-drying or partially crosslinking and providing a further treatment station in which a final curing or crosslinking of the intermediate or adhesive layer by heat or energy input, for example by thermal energy, UV radiation, microwave radiation, electron radiation and / or beta radiation 8th takes place, before or after blow molding.

Furthermore, there is also the possibility for the intermediate or adhesive layer 8th to use a hotmelt or a hot melt or hot melt adhesive-like material, which then for example in the preheating 10 on the preforms 3 , is preferably applied by spraying and which cools after blow molding. Dry or predry the intermediate or adhesive layer 8th before the transfer of the preforms 3 to the blow molding machine 14 but has the advantage that surfaces of the blow molds 12 by the for the intermediate or adhesive layer 8th used material should not be contaminated.

After treatment, the bottles 2 from their respective holding and centering element 6 separated and over a transport star 19 forwarded to an external carrier. The respective holding and centering element 6 is sent to the transport star via an internal transport route 5 for receiving another preform 3 recycled.

The invention has been described above by means of an embodiment. It is understood that numerous changes and modifications are possible without thereby departing from the inventive concept underlying the invention. So it is of course also possible, the transport system for the preforms and bottles 2 also different, as described above, form.

LIST OF REFERENCE NUMBERS

1

investment

2

bottle

2.1

bottle opening

2.2

bottle body

2.3

bottle wall

3

preform

3.1

open end of the preform

3.2

Section of the preform

4

Feed dog or preform feeder

5

transport star

6

Holding and centering element

7, 7a

treatment station

8th

Intermediate or adhesive layer

9

sprayer

9.1

jet

10

preheating

11

transport star

12

blow

13

rotor

14

blow molding machine

15

transport star

16

treatment section

17

Imprint or printing or decorative layer

18

applicator roll

19

transport star

20

external transporter

21

internal transport route

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102006001223 A1 [0003]

Claims (15)

Process for the treatment of preforms ( 3 ) made of plastic, preferably made of PET, PE, HDPE or PP for the production of containers by blow molding, characterized in that the preforms ( 3 ) before blow molding the containers ( 2 ) with an intermediate or adhesive layer ( 8th ) which is stretched during the blow molding process together with the material of the respective preform. A method according to claim 1, characterized in that the intermediate or adhesive layer ( 8th ) or the material forming this layer prior to the transfer of the preforms to the blow molding machine ( 14 ) or to local blow molds ( 12 ) is at least predried and / or partially crosslinked, preferably by the action of heat during a preheating of the preforms required for blow molding ( 3 ). A method according to claim 2, characterized in that before and / or after the blow molding drying or crosslinking of the predried and / or partially crosslinked intermediate or adhesive layer ( 8th ) he follows. Method according to one of the preceding claims, characterized in that the intermediate or adhesive layer ( 8th ) or the material forming this layer before transferring the preforms to the preheating section ( 10 ) or during the residence time in the preheating section ( 10 ) with an intermediate or adhesive layer ( 8th ). Method according to one of the preceding claims, characterized in that the material for the at least one intermediate or adhesive layer ( 8th ) is selected so that this layer has an optimum adhesive strength for the blow molding on the respective container ( 2 ) to be applied ( 17 ) and / or ensures optimum wetting of the surface to be printed with at least one printing ink. Method according to one of the preceding claims, characterized in that for the intermediate or adhesive layer ( 8th ) a material is used which has the barrier properties of the respective blow-molded container ( 2 ) is improved by at least 10% and / or the surface tension of the container is increased to a value greater than 45 mN / m, in particular greater than 50 mN / m. Method according to one of the preceding claims, characterized in that for the intermediate or adhesive layer ( 8th ) a nanoparticle, for example, nanofibers and / or nanotubes contained material is used. Method according to one of the preceding claims, characterized in that the respective imprint or the printing layer formed thereby ( 17 ) and the intermediate or adhesive layer ( 8th ) can be adjusted by the choice of material and / or by the type of drying and / or crosslinking such that the adhesive strength or adhesion rates between the intermediate or adhesive layer ( 8th ) and the container wall ( 2.3 ) is greater than the adhesive strength or adhesion rates between the intermediate or adhesive layer ( 8th ) and the print layer ( 17 ), whereby the adhesion within the printing layer ( 17 ) is higher than the adhesion of this layer to the intermediate or adhesive layer ( 8th ) or that the adhesion or adhesion rates between the intermediate or adhesive layer ( 8th ) and the print layer ( 17 ) is greater than the adhesive strength or adhesion rates between the intermediate or adhesive layer ( 8th ) and the container wall ( 2.3 ), wherein the adhesion at least within the intermediate or adhesive layer ( 8th ) is higher than the adhesion of this layer to the container wall ( 2.3 ). Method according to one of the preceding claims, characterized in that the intermediate or adhesive layer ( 8th ) by spraying and / or rolling on the preforms ( 3 ) is applied. Method according to one of the preceding claims, characterized in that for the intermediate or adhesive layer ( 8th ) a hotmelt is used, which preferably during the preheating or heating of the preforms ( 3 ) is applied to this. Method for printing, preferably for digital printing on containers made of plastic, preferably made of PET, PP, HDPE or PE, using preforms ( 3 ) are produced by blow molding or stretch blow molding, characterized in that the preforms ( 3 ) before blow molding the containers ( 2 ) according to one of the preceding claims with at least one intermediate or adhesive layer ( 8th ). Device for producing containers ( 3 ) made of plastic, preferably of PET, PE, HDPE or PP from preforms ( 3 ) by blow molding, comprising at least one transport star ( 5 ), a preheating line ( 10 ) and a blow molding machine ( 14 ), characterized in that this device comprises at least one spraying device ( 9 ) for applying an intermediate and adhesive layer ( 8th ) on the preforms ( 3 ). Apparatus according to claim 12, characterized in that the spraying device between the preheating ( 10 ) and the blow molding machine ( 14 ) or on the blow molding machine ( 14 ) is arranged. Apparatus according to claim 12, characterized in that the spray device before or along the preheating ( 10 ) is arranged. Apparatus according to claim 14, characterized in that the spraying device at a transport path along the preheating ( 10 ), wherein the transport path relative to the preheating ( 10 ) comprises at least one down and one lead.

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