JPH02122914A - Label within synthetic die - Google Patents

Abstract

PURPOSE: To prevent wrinkling and cracking by a method wherein a label having a backing material constituted of a synthetic thermoplastic film of which the thermodynamic characteristics are substantially the same as a plastic vessel to be used with the label attached thereto is disposed in a mold for blow or injection molding before the vessel is molded. CONSTITUTION: A sheet of a porous thermoplastic film constituted of a biaxially extruded polyethylene/polystyrene copolymer and resistive to wrinkling, curling and cracking and having a surface so shaped as to enable attainment of a print of high quality is supplied. Indications are printed at least on one surface of the sheet and the sheet is cut into a plurality of individual labels so that each label has the printed indication. One of the labels is disposed in a mold, a high-density polyethylene vessel is blow-molded in the mold, the label is made to adhere to the outer surface of the blow-molded vessel and then the vessel is removed from the mold. Thereby the plastic vessel labeled in the mold is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates generally to labels, and more particularly to in-mold labeling (IM).
L) High-density polyethylene (HDPE) plastic containers molded by equipment and in-mold labeling methods and labels made from synthetic thermoplastic films for use therewith.

[Conventional technology]

Plastic containers and bottles can hold many different types of materials,
For example, light liquids (e.g. dishwashing detergent), heavy liquids (e.g.
A wide variety of shapes and sizes are used today to contain laundry detergents, motors, vegetable oils, cleaning agents, etc. Typically, these containers are manufactured from plastic, especially high density polyethylene (HDPE), by blow molding or injection molding.

HDPE containers typically have a label attached to them that displays the product's trade name and also includes other information. The label may simply be applied, such as with an adhesive, after the container is formed. However, the label can also be applied to the container during the container molding process. The technique of applying labels to containers during such molding operations is commonly referred to as in-mold labeling (IML) or decorative molding.

In-mold labeling is well known in the art.

Typically, the in-mold label is placed in a blow or injection molding machine prior to molding the container. After the label is placed, the container is formed by blowing or injecting the plastic into a mold. The label (which may also contain an adhesive) is attached or affixed to the exterior surface of the container. In some cases, the label is partially or completely embedded in the plastic surface of the HDPE container.

Although the present invention is described and illustrated with respect to HDPE containers for illustrative purposes, in-mold labeling also applies to the molding of propylene multilayer bottle and pond type plastic containers formed by blow molding, injection molding, or other molding methods. It should be understood that it can be used.

Many devices are known for in-mold labeling of containers. For example, in 1973, Langecke
U.S. Patent No. 3,759,643, issued to U.S. Pat. The apparatus includes a blow mold having a cavity for accommodating the hollow body and a member movable toward the cavity. The member includes a portion that carries a label that is applied to the hollow body during movement of the member towards the cavity. The mold is provided with an exhaust hole for exhausting air between the hollow body and the label.

Bar times in 1984
U.S. Patent Section 4,479,644 issued to
Another in-mold labeling apparatus is disclosed. The device is
It is equipped with a label applicator for applying a label to the mold cavity of the rotary mold unit. The applicator includes an extensible fluid motor that moves the suction head back and forth between a label pick-up position and a labeled tube position. A sensor provides timing between the applicator and the label application location within the mold cavity.

Other in-mold labeling devices and methods are disclosed in U.S. Pat.
No. 87, No. 3.287.188, No. 3,272.88
No. 1, No. 3.287,198, No. 3.292,209
No. 3,324,508, No. 3,657.405, No. 3,759.645, No. 3゜801.689,
No. 4.359,314, No. 4.397. H5, No. 4
．． No. 549.883 and No. 4. [Disclosed in No. i05.462.

[Problem to be solved by the invention]

Although in-mold labeling has been used for many years on a wide variety of product containers, the labeling technology itself has made little progress, and several notable issues remain unresolved in the industry. . For example, conventional in-mold labeling methods typically utilize paper-based labels with or without a suitable adhesive. Conventional paper labels of this type have been found to wrinkle, curl, and crack when exposed to the heat and moisture associated with container forming.

As a result, the label may not adhere completely to the outer surface of the container. Additionally, wrinkles, curls, or cracks in the label detract from its appearance and make the container unpopular in the marketplace. Additionally, labels applied to certain types of containers (eg, shampoo) that are exposed to extremely humid environments (eg, showers) may eventually tear and peel away from the container. Additionally, some types of paper labels are not resistant to abrasion and scuffing, resulting in portions of the label being worn away during shipping, resulting in an unsightly appearance of the container and label.

Additional problems may arise during container molding due to differences in thermodynamic properties between HDPE plastic containers and paper labels. At the relatively high temperatures associated with the molding process, this difference in thermodynamic properties can create stresses on the container surface that can result in undesirable bulges or depressions in the area of the container that will underlie the label. Such bulges or depressions can cause changes in the volume of the container, resulting in overflowing or filling.

Finally, defective containers may be produced during the molding process. To reclaim valuable raw materials, it is often desirable to recirculate defective containers. Removal of in-mold labels from such defective containers can be time consuming and expensive.

For example, one method of recycling defective containers involves grinding the containers along with the labels into a relatively coarse powder.

The paper label material must then be separated from the plastic material in some way.

For example, in 1983, Nowicki
U.S. Pat.

This patent teaches that labels can be made from paper and metal foil and can contain wax-containing adhesives.

Similarly, in 1986, Matuszak
), U.S. Patent Section 4,599,131 issued to
A machine for removing labels from plastic containers is disclosed that includes the step of removing a label affixed to the container during processing within a mold. Although such methods have been devised, these methods require additional equipment and time, thereby increasing the cost of manufacturing HDPE and other blow molded containers.

Although these problems have existed for many years, IM
The L technology does not strive to improve the labels themselves as a possible improvement method, but tends to use IML labels, which could traditionally be done manually.

For example, in 1986, Nowicki
U.S. Patent Section 4.595,449, issued in

The No. 1, No. 1, No. 1, No. 1, No. 1, No. 1, No. 1, No. 1, 2002, describes a label preferably made of extensible paper, such as porous kraft paper, coated with an adhesive, such as a gel lacquer, which becomes soft and tacky between 170 and 180'.

U.S. Patent No. 4,418,033, issued to Hatakeyama in 1983, describes a transfer foil formed by laminating a base film, a release agent layer, a printing layer, and an adhesive layer. has been done.

U.S. Pat. There is. This patent relates to bubble-free application of labels.

US Pat. No. 3,324,508, issued to Dickinson in 1967, discloses a label secured by an electrostatic charge. The label itself is in the form of a thin flexible extensible film capable of retaining an electrostatic charge and is fused to the plastic of the container.

As specific materials, reference is made to olefinically unsaturated hydrocarbons, ie homopolymers and copolymers of ethylene, propylene, styrene, and cellulosic polymers. Low-density polyethylene film is also mentioned.

Borkman in 1966
U.S. Pat. No. 3,292,209, issued in 1997, describes labels made of olefin polymers or copolymers that are characterized by low softening points.

U.S. Pat. No. 3,227,787, issued to Battenfield in 1966, discloses a plastic or paper label having a layer of weldable plastic material or bondable material depending on the material to which the label is attached. Are listed.

U.S. Pat. No. 3,550,197, issued to Szajna et al. in 1970, describes the use of a tinting agent that increases the ability to withstand heat during the molding process but is easily removable with a solvent. taught.

The adhesive is used with Mylar inserts in the mold section.

US Pat. No. 3,151,193, issued to Thornton in 1964, discloses the use of printed polyethylene films as labels in an in-mold labeling apparatus.

US Pat. No. 3,108,850, issued to Brandt in 1963, discloses the use of conventional polyolefin sheets that can be adhered to containers.

One type of label is made from branched polyethylene that has been pretreated with a fire treatment or a corona discharge treatment. The label may have an adjacent plastic material, such as a self-supporting film.

U.S. Pat. No. 4,323,411, issued in 1982 to Uhlig, discloses the use of a laminated foil with a print sandwiched between two layers of the same thermoplastic material from which the container was molded. A shaped label is disclosed.

US Pat. No. 4,289,817, issued to Valyi in 1981, describes liners for use in blow molding made from a single plastic or from several different plastics. Typical liner materials include acetal polymers, polyolefins, ionomer resins, polyaromatic copolymers, polystyrene, polyvinylidene chloride, polyvinyl chloride, polycarbonate, and polyacrylonitrile.

US Pat. No. 4,282.058, issued to SaunderS in 1981, discloses curl-resistant paper labels with increased water retention that can be used in blow molding processes.

Labels use conventional metal-paper laminates, metallized papers, or varnished papers as substrates with certain coating materials.

Although the above developments are generally known, any of them can be constructed from economical commercially available materials that can withstand the stresses of container forming and resist curling, wrinkling and cracking. The aforementioned challenges in producing in-mold labels that exhibit compatibility with thermodynamic and chemical properties, yet can provide a high quality, abrasion-resistant and scratch-resistant printed surface It is not something that can be solved.

Therefore, an object of the present invention is to solve the problems of the prior art as described above, and to provide an in-mold label having the above-mentioned excellent characteristics and advantages, a plastic container with an in-mold label attached, and a method for manufacturing the same. Our goal is to provide the following.

[Means to solve the problem]

According to the invention, a porous thermoplastic is constructed from a twin-extruded polyethylene/polystyrene copolymer and has a shaped surface that is resistant to wrinkling, curling and cracking and allows for high quality printing. providing a sheet of film, printing an indicia on at least one side of the sheet, cutting the sheet into a plurality of individual labels, each label having a printed indicia, and molding one of the labels; placing a high-density polyethylene container in the mold, applying the label to the outer surface of the blow-molded container, and removing the container from the mold. A method of manufacturing a plastic container is provided. Furthermore, such a method also provides for plastic containers of the type produced by blow molding, preferably high-density polyethylene containers, characterized in that an in-mold label of porous thermoplastic film is adhered to the outer surface. provided.

[Operation and mode of the invention]

The present invention provides an excellent IML configuration that avoids the drawbacks of known in-mold labels used for HDPE containers and the like formed by in-mold labeling devices and labeling methods.

The label is constructed from a material that can withstand the stresses of container molding and can be recycled with the container. This label has print quality comparable to currently used paper labels and can be used with existing in-mold labeling equipment.

In a preferred embodiment, the invention encompasses a label having a backing material comprised of a synthetic thermoplastic film having thermodynamic properties substantially similar to the plastic container to which the label is attached.

A heat activated adhesive (or heat sensitive adhesive) is applied to the container contacting surface of the backing material. Print the selected imprint on the opposite surface of the backing material. The label is placed in a blow or injection mold prior to container molding. At the same time as the container is being formed, the adhesive is activated and adhered to the label or exterior surface of the bottle.

A preferred embodiment of the I M L label of the present invention is made from a monolayer film of twin-extruded polyethylene/polystyrene copolymer, which may also be provided with a print-enhancing coating. The film is manufactured as a sheet that can be punched and printed with suitable labeling. Most importantly, labels constructed from the polyethylene/polystyrene films of the present invention can be printed on conventional IML labeling equipment and can be printed on conventional IML labeling equipment on HDPE containers.
It can be attached using molding equipment.

Good label plastic compositions can withstand the stresses of container molding and also resist curling, especially in humid environments.
It is resistant to wrinkles and cracks.

Additionally, a good I M L label composition is fully compatible with the thermodynamic and chemical properties of the container, thereby preventing container blistering or warping and allowing recirculation of container raw materials.

Further features of the invention will become apparent from the detailed description below.

〔Example〕

A preferred construction of the superior IML label of the present invention uses a porous thermoplastic film comprised of a twin-extruded single layer polyethylene/polystyrene copolymer. An example of this type of film is the Process for Making Porous Articles from Blends of Crystalline Polyolefins and Resin Acid Metal Salts.
sforProducing Multicel
lular Articles froma B
lend of a Crystalline
Polyolefin and aMetal
About Re5inate) J Jack (J, Jac
U.S. Patent No. 4 issued March 4, 1980 to k) et al.
．． No. 191,719, the disclosure of which is incorporated herein by reference. These films are manufactured by BXL Plastics under the name POLYART2.
SLtd, ) and Arjobex
) is sold from. To improve the printing quality of thermoplastic films, calcium carbonate and/or
Or you can apply white clay paint. Such a thermoplastic film having an acrylic bonded clay calcium carbonate coloring coating for printing promotion is manufactured by POLYART2 Plus Rigid.
) under the name BXL Plas.
tics, Ltd.) and Arjopex (Arj
obex), and the excellent IML of the present invention
Can be used when manufacturing labels. This coating ensures a high-quality print that will not smudge or peel off the film surface. The coating also makes it possible to improve the abrasion and scratch resistance of the finished IML label.

The physical properties of the thermoplastic film described above are as follows.

First surface density 0.77y/cm3 Tensile strength 36.000K N / is elongation at break 80% Initial tear resistance 5ONmm Sca
nt) Modulus Folding Strength 105 The films described above are printed with suitable labeling in a conventional manner. It was found that the printing quality of the thermoplastic film ML label of the present invention was equivalent to that of conventional paper labels. If the label is used as a peel label, the selected label indicia can also be provided on the inside surface of the backing material. In either case, a heat activated adhesive or other adhesive may also be applied to the label sheet. 0M labels can then be punched out in the usual manner.

〔Effect of the invention〕

The IML labels of the present invention can be used in conventional in-mold labeling equipment in the same way as conventional paper labels;
The plastic nature of the label prevents it from wrinkling and cracking when exposed to heat and moisture during container molding. Additionally, the heating and cooling properties of the thermoplastic film are substantially similar to the attached HDPE plastic container, thereby preventing container deformation, blistering and warping.

The I M L labels of the present invention were also found to have higher moisture and solvent resistance than conventional paper labels. These properties reduce the possibility of the edges of the label flipping over and extend the shelf life of the label's appearance, especially when the label is attached to a plastic container. Additionally, IML labels made from thermoplastic film have increased tear and burst strength over traditional paper, allowing the use of thinner labels than are available with corresponding paper labels.

Although the invention has been described with reference to preferred embodiments,
Those skilled in the art will appreciate that various changes may be made in the form and details of the invention without departing from the spirit and scope of the invention.

Applicant: Multi-Color, Corporation Agent: Patent attorney Masaaki Yonehara

Claims (8)

[Claims] (1) A sheet of porous thermoplastic film constructed from twin-extruded polyethylene/polystyrene copolymer and having a shaped surface that is resistant to wrinkling, curling, and cracking and capable of high-quality printing. printing an indicia on at least one side of said sheet, cutting said sheet into a plurality of individual labels, each label having a printed indicia, and placing one of said labels in a mold. a plastic with an in-mold label, comprising the steps of blow-molding a high-density polyethylene container in the mold, adhering the label to the outer surface of the blow-molded container, and removing the container from the mold. Method of manufacturing containers. 2. The method of claim 1, including the step of: (2) applying to said film an acrylic-bonded clay calcium carbonate colored paint to improve the printing properties of the sheet. 3. The method of claim 2, including the step of: (3) applying a heat activated adhesive to one side of the sheet to improve the adhesion of the label to the container. (4) A high-density polyethylene container of the type manufactured by blow molding, characterized in that an in-mold label made of porous thermoplastic film is adhered to the outer surface. 5. The container of claim 4, wherein said thermoplastic film comprises a thin twin-extruded polyethylene/polystyrene copolymer sheet. 6. The container of claim 5, wherein said sheet includes an acrylic bonded clay calcium carbonate coloring paint to improve the printing properties of the label. (7) The density of the above film is approximately 0.77 g/cm^2,
Claim 5: The tensile strength is about 36,000 KN/m^2.
Container as described. 8. The container of claim 6 including a heat activated adhesive applied to the label to adhere the label to the container.