EP0387916A2

EP0387916A2 - Self adhesive labels

Info

Publication number: EP0387916A2
Application number: EP90105727A
Authority: EP
Inventors: Thomas Norman Gaunt
Original assignee: John Waddington PLC
Current assignee: John Waddington PLC
Priority date: 1981-12-15
Filing date: 1982-12-07
Publication date: 1990-09-19
Also published as: ES8401404A1; AU9155882A; AU6874387A; CA1248412A; ES518164A0; ZA829173B; JPH0563798B2; EP0184610A3; AU562908B2; EP0387916A3; JPS58114083A; AU581119B2; DE3278255D1; EP0081963A3; NO824179L; ATE33075T1; EP0081963A2; DK555282A; EP0081963B1; EP0184610A2

Abstract

The invention discloses self adhesive labels in roll form which are for the high speed application to moving articles. A base web material is coated on one side with release material such as a polymerisable silicone resin, and on only a fraction of the other side with pressure sensitive adhesive, to enhance release of the web during unrolling and to prevent extrusion of the adhesive out of the end of the roll. The web has sprocket holes for controlling the feed of same through an applicator machine which preferably cuts the individual labels from the web leaving a skeletal waste.

Description

This invention relates to self adhesive labels and in particular concerns labels which are supplied in roll form. The labels will mainly be for application, using suitable machinery, to individual articles or objects.
Pressure sensitive labels find wide application in the field of produce marketing. For example, in supermarkets and other stores the products on sale are typically priced by means of small pressure sensitive labels which are applied to the product, and frequently these labels have to be changed because of price change, making consumption of such label enormous. These labels are known as "secondary" labels because they do not primarily indicate the nature of the product but rather some specific aspect of the product such as the price.
Also, huge quantities of labels known as primary labels which are applied to containers such as bottles and cans to identify the contents are used. Generally speaking, secondary labels are applied by hand or by hand held machinery at the retail outlet whereas the primary labels are applied where the product is filled into the container in which it is held.
Typically, primary pressure sensitive labels are mounted on a carrier or backing web which is normally a web of paper coated with a suitable release material such as a silicone compound. The adhesive labels are applied to this carrier or backing web for transportation, storage and utilisation, but the labels can readily be peeled from the backing web as there is a much stronger bond between the adhesive and the material of the label, than between the adhesive and the release material.
Not only is the backing web superfluous after the labels have been peeled therefrom and consumed, but the manufacture of the backing web is a specialist process, and must be performed under carefully controlled conditions. The equipment to produce the backing web is expensive, and is extremely large, so that only a very few companies are able to finance and perform the backing strip manufacture.
There have been proposals to eliminate the backing strip in adhesive labels, but such proposals have not met with any commercial success. One of these proposals is set forth in U.S. Patent No. 3,575,788 wherein a backless roll of secondary labels is produced by printing on clay coated paper on one side with a nitro cellulose base ink, and by covering the ink with a heat - cured thermosetting silicone resin release coating, the other side having a pressure sensitive adhesive applied thereto. The silicone release coating is cured at a temperature of 350^o to 500^oF.
It has been proposed as disclosed in U.S. Patent 2,845,728 to provide pressure sensitive secondary labels in the form of a strip or tape, carried by a small dispenser for hand use. The strip of labels comprise an adhesive surface on one side, and a release characteristic on the other side so that the strip can be wound without a backing sheet into roll form. The individual labels are torn from the strip manually by a severing edge on the dispenser, and the labels are applied again manually to products such as fruit and grocery produce.
U.K. Patent Application 2,013,613 also discloses that it is known to provide a roll of secondary labels, and on one side of the web is pressure sensitive adhesive whilst on the other side is a release coating to enable the web to be wound into roll form without the use of a backing strip. The roll of labels is placed in a "labelling gun" to enable the feeding of the web to unroll same, and the severing of individual labels from the roll by transverse cutting thereof. No detailed description is given of how the labelling gun operates, but such guns are probably small hand carried items as they are described as being of a type which are carried by clerks to enable the prices of goods to be marked on the goods by application of the labels thereto. This specification as the United States Patent 2,845,728 is therefore more concerned with the provision of secondary small price secondary labels as opposed to the primary labels which are applied to articles such as bottles and cans by application machinery under factory conditions.
Where primary labels are to be applied to articles such as bottles and cans, it has been traditional to use labels which carry heat or moisture activated glue, or to provide that the pressure sensitive labels are carried on a backing sheet which is release material coated.
There has been no disclosure of or attention given to the construction of a continuous web of material for the manufacture of the primary labels of a pressure sensitive nature, and which can be applied by high speed machinery under factory conditions.
The invention provides a roll of self adhesive labels for the application of the labels individually by machinery to articles which are moved one by one by machinery relative to the station at which the labels are applied.
According to the invention there is provided a roll of backingless self adhesive labels comprising a web on which the labels are printed in equally pitched arrangement, characterised by the combination of the features known per se of

a) the web is for feeding through a machine which cuts the labels from the web leaving a skeletal waste;
b) the web has no cuts or weakening lines in said web for the assistance of the cutting of the labels from the web;
c) on one side of the web is a pressure sensitive adhesive enabling the labels to be adhered to articles when the labels are cut from the web; and
d) on the other side of the web is a pressure release surface which contacts the web when in the roll form.

The web is preferably of a relatively non-extensible material so as to enable the individual labels to be cut therefrom.
The web material defining the labels may be of a thickness consistent with the thickness of the labels as conventionally used.
The release coating may be applied to the web by rollers, gravure cylinders or hot melt applicators to provide a surface having a release characteristic. The coating may for example contain non-migrant repellants, and in particular, polymerisable silicone polymers. The coating may for example be a solvent heat cured coating, an aqueous system, solvent free or UV cured, examples of the above are as follows:

Solvent Heat Cured

A) Silcolease* (TM) 425 (30%) (ICI) 100 parts by weight Catalyst 62A (ICI) 4 parts by weight Catalyst 62B (ICI) 4 parts by weight Toluene 200 parts by weight Curing Time at 120°C 10 seconds
100°C 15 seconds
90°C 20 seconds Dry off solvent prior to cure approx. 5 seconds. B) a) Syloff 7046 Basic polymer dispersion.
b) Dow Corning 7047 Curing agent for Q2-7046.
a) and b) are used in ratio of 10:1 typically.
c) Q2-7090 (Dow Corning) Premium release addi tive. Is used in varying proportions to lower release levels of basis 02-7046.
d) Q2-7089 (Dow Corning) Release modifying agent. Can be used in varying amounts to raise level of release of Q2-7046 and gives stable modified release levels.
e) Q2-7127 (Dow Corning) Accelerator for 02-7046. Is used in minute quantities to accelerate the cure rate of Q2-7046. Especially useful for low temperature curing on substrates such as polyethylene film.
f) Syloff 297 (Dow Corning) Anchorage additive. Necessary to provide abrasion resistance for off-line work (except using PEK).

In the following proportions by volume.
	1	2	3	4	5
Syloff 7046	20	20	10	16	13.4
Crosslinker 7047	2	2	1	2.2	3.2
Q2-7090	-	-	-	-	2
Q2-7089	-	-	-	2	-
Q2-7127	-	-	0.04	-	0.03
Syloff 297	-	0.2	-	0.2	-
Solvent	78	78	89	80	82

Bath 1 - Standard bath for in-line use or off-line on certain substrates such as PEK.
Bath 2 - Standard bath for off-line use, using Syloff 297 anchorage additive.
Bath 3 - Special low solids bath for coating films such as polyethylene. Solvent choice important and ethyl acetate best. Uses Q2-7127 as accelerator.
Bath 4 - Controlled release bath. Features Q2-7089 as release modifier and Syloff 297 as anchorage additive.
Bath 5 - Premium release formulation involving incorporation Q2-7090 low viscosity fluid and additional Q2-7127 to restore catalyst level.

These are only typical baths and levels of accelerator, release modifier and premium release additive can all be varied.

Curing Conditions

Bath 1 and 2 cure in 8-12 seconds at 140^oC depending on substrate nature.
Bath 3 will cure in 15-20 seconds at 70^oC.
Bath 4 cures typically in 15 seconds at 140^oC.
Bath 5 cures in 30 seconds at 100^oC or 10 seconds at 140^oC.

Aqueous Systems

A & B SYL OFF 1171* (50%) (Dow Corning) Organopolysiloxane 14 parts by weight.
C.M.C. (Carboxy methyl cellulose) 2 parts by weight.
Catalyst 1171A (Dow Corning) Organo-tin Acylate 1.4 parts by weight.
or Catalyst 164 (Dow Corning) Organo-tin Mercaptoacetate 3.5 parts by weight.
Water To give 100 parts by weight.
Cure time 10 seconds at 120^oC

Solvent Free Silicone

A) Syloff 7044 (100%) (Dow Corning) 100 parts by weight.
Crosslinker 7048 (100%) (Dow Corning) 4 parts by weight.
B) Coating Q2-7069 (100%) (Dow Corning) 100 parts by weight.
Crosslinker 7048 (100%) (Dow Corning) 4 parts by weight.

Cure time

A) 40 seconds at 120^oC 10 seconds at 170^oC.
B) 30 seconds at 170^oC

U.V. Cured

A) Silicone Dehasiv VP 1502 (100%) (Wacker) 100 parts by weight.
Crosslinking Agent VP 1503 (100%) (Wacker) 4 parts by weight.
Catalyst OL (100%) (Wacker) 0.4 parts by weight.
B) Silicone X-62-7004 (100%) (Shin-Etsu Chemical Co. Ltd) 100 Parts by weight.
Catalyst X-92-09 5 (100%) (Shin-Etsu Chemical Co. Ltd) 10 Parts by weight.

Cure rate 0.6 seconds with high pressure mercury Vapout U. V. Lamp (160 W/cm).
The amount of release coating applied may be in the order of 0.1 to 1.5 grams/sq. metre depending upon the web. The pressure sensitive adhesive may be applied by conventional means, and typicallay may be a solvent or water based emulsion of which the solvent or water is dried from the web after application. The pressure sensitive adhesive may for example be hot melt, water based, or solvent based, examples of which are as follows:

Hot Melt

Elvax *40-P (Du Pont) (Ethylene-vinyl acetate resin) - 40 parts by weight.
Piccovar* L-60 (Hercules Inc.) (Hydrocarbon resin) - 60 parts by weight.
Irganox *1010 (Ciba Geigy) (Antioxidant) - 0.5 parts by weight.

Aqueous

Indatex SE2229S (Industrial Adhesives Ltd)

Solvent

Vinalak 5150 (Vinyl Products Ltd)
The labels may be colour printed by any suitable method such as letter press, flexographic, gravure or offset litho.
For the web material, it is preferred to use polypropylene or high density polyethylene film, including substantial proportions of particulate inorganlc material.
Typically, the inorganic material may be included in the range 20 to 50% of the web by volume, and in the preferred case the web is polypropylene ethylene sequential copolymer, as described in our British Patent No. 1,544,143 filled with 40% talc.
Embodiments of the present invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, wherein:-

Fig. 1 is a perspective view ofa roll of labels for use in the present invention; and
Fig. 2 illustrates how the labels of Fig. 1 are applied to box shaped products.

Referring firstly to Figs. 1 and 2 of the drawings, in Fig. 1 there is shown a web 10 having labels 14, each provided with printing 16.
The web 10 is made up of a central substrate web which is of a non-fibrous and substantially inextensible material and on one side of which is applied a pressure sensitive adhesive coating and on the other side is applied a release coating. The substrate, adhesive coating and release coating are of a nature as described herein, and the web is wound so that the adhesive coating is to the inner side of each coil and contacts directly on the release coating of the adjacent inner coil. This arrangement enables the web to be easily unrolled. The web may be wound on a suitable core.
In producing the web 10 as illustrated in Fig. 1, the printing 16 (single or multi coloured and of any desired pattern and/or content) is applied to the substrate prior to the application of the release coating.
Although not shown in Fig. 1, the web 10 has sprocket holes at each side thereof which will be arranged by suitable sprocket wheels or rollers and the web will be indexed forwards towards the product to be labelled.
The web 10 carries printing 16 which repeats at pitch length P, but the web has no perforations or lines of weakening. The web defines labels which have to be cut from the web by suitable cutting equipment located in the region of an application head as explained in relation to Fig. 2 so that individual labels are cut from the web immediately prior to or during application of the label to the article to which the label is being applied.
In all embodiments the adhesive covers only a fraction of the web surface at one side, to increase the ease with which the labels can be applied to the products and to limit extrusion of the adhesive out of the side of the roll of labels.
Fig. 2 shows in somewhat greater detail, how labels in roll form as shown in Fig. 1 may be applied to box shaped products 40. The roll of labels is indicated by numeral 42 and is unwound from this roll by a tractor unit 44 having a suitable sprocket feed device which engages the holes in the margins of the web 10 (the said holes are not shown in the drawings) and is fed through a removal and application station 46. The skeletal residue of the web 10 is wound into roll form as shown by numeral 48.
The adhesive side of the web 10 is the upper side and all surfaces which contact this adhesive side are required to be of a nature so as not to adhere to the adhesive. Such surfaces may be defined by silicone release material.
The removal and application station 46 comprises an upper pressure nip roller 50 (silicone coated) and a lower vacuum cylinder 52 around which the web 10 laps slightly as shown in Fig. 2, and which has a plurality of circumferentially spaced ports 54 which connect with axially extending passages 55, which are selectively connectable to a source of vacuum or, when at detachment position 56, with a blast of air under pressure. A valve plate 58 at one end of the cylinder controls the connection of the passage 55 to the source of vacuum and the blast of air in that said plate 58 has an arcuate port 60 coupled to the source of vacuum and a port hole at position 56 connected to the air under pressure. In use, the cylinder 52 rotates in the direction of arrow 62 whilst the plate 58 remains stationary and each passage 55 which registers with port 60 is connected to the source of vacuum. Each passage 55 which leaves register with port 60 arrives first at the position 56 where it receives a blast of air under pressure, and then the passage is blanked off until it once more reaches the port 60.
Operation of the unit 46 will be understood from the above. The individual labels 14 are detached by the vacuum at the nip between roller 50 and cylinder 52, and travel round with the cylinder 52 until they reach station 56 at which they are progressively applied to the products 40 which are moving as indicated by arrow 63, in synchronsim with the feed of the labels. The labels and products are fed on a continuous basis, and at high speeds.
It is estimated that the apparatus shown in Fig. 2 will be capable of applying labels at the rate of approximately 200/min in part because the label roll has no backing strip.
This application is divided out of European Patent Application No. 85110025.5 which in turn is divided out of European Patent Application No. 82306505.7.

Claims

1. A roll of backingless self adhesive labels comprising a web on which the labels are printed in equally pitched arrangement, characterised by the combination of the features known per se of

a) the web is for feeding through a machine which cuts the labels from the web leaving a skeletal waste;

b) the web has no cuts or weakening lines in said web for the assistance of the cutting of the labels from the web;

c) on one side of the web is a pressure sensitive adhesive enabling the labels to be adhered to articles when the labels are cut from the web; and

d) on the other side of the web is a pressure release surface which contacts the web when in the roll form.

2. A roll of self adhesive labels as claimed in Claim 1, characterised in that the web has sprocket holes at the edges thereof for the registration of the web as it passes through an applicator machine and the labels are printed on said web so that the labels are in pitch register with said sprocket holes.

3. A roll of self adhesive labels characterised in that adhesive covers only a fraction of the web surface to limit the extrusion of the adhesive and the side of the roll of labels.