KR100904959B1 - Heat-shrinkable clear label - Google Patents

Abstract

A heat-shrinkable clear label is provided to remove a label which is attached to a container by dipping in the warm water, or hot air, or hot steam for 20 seconds. A heat shrinkable clear label is formed as following. The heat shrinkable film layer and the adhesion layer in which the shrinkage ratio of the length direction or the width direction is more than 30% for 20 seconds in 80°C are included. The adhesion exfoliation drawing indicated as below equation 1 is 70 ~ 100. The adhesion(m0) of the adhesion layer at the room temperature(25°C) is 160~1080 gf/in. The rate of temperature change((m0-m1)/m0x100) of the adhesion(m0) at the room temperature and the adhesion(m1) at 60°C are 42 ~ 85. In 80°C, the time(DeltaT) in which label exfoliates from adherent is 12 ~ 52 second. In the room temperature, the residue rate(eta) of label is less than 5% after the cross cut in exfoliation.

Description

Heat shrinkable clear label {HEAT-SHRINKABLE CLEAR LABEL}

The present invention relates to a heat shrinkable label that is easy to recycle and suitable for use in containers such as glass bottles.

Adhesive label refers to an adhesive coated label that is applied by itself or applied under pressure, and is applied by moisture (paper attached by applying water to the surface where the adhesive is applied), heat (heat adhesive) or adhesive (plain paper). It is distinguished from the general label that must be applied, characterized in that the pressure-sensitive adhesive is precoated and protected by a release paper. In addition, since the release paper is peeled off and the label is applied by the adhesive-treated side, the adhesive is exerted even without applying moisture or heat. The adhesive label is a pressure-sensitive label that requires extremely low pressure to adhere. Also called.

Among adhesive labels, plastic film labels can be used in glass or plastic containers to enhance visual aesthetics, and mechanical properties such as tensile strength and friction resistance are excellent, and the demand is increasing compared to conventional paper labels. have. In addition, since most of the containers used in the beverage industry due to environmental problems are recovered and recycled after use, plastic labels are in the spotlight especially in that labels attached to such containers can be collected and recycled.

Recently used plastic labels are based on a structure having a uniaxial or biaxially stretched polymer film layer and an adhesive layer for attaching the label to a container or the like, and are generally at least one minute in hot water at 80 ° C to 100 ° C. The label is peeled off when immersed in the wash solution.

However, such a conventional plastic label, firstly, the cleaning cost of the recycling container increases as some of the adhesive remains in the container upon peeling off the label, and further cleaning is necessary, and secondly, the organic material used for the adhesive layer during the cleaning Dissolution causes contamination of the cleaning solution, which incurs additional costs for environmental pollution and cleaning of the cleaning solution, and the third container is recycled, so the label removal rate is slow.

Accordingly, an object of the present invention is to improve the recyclability of the label and the container because there is almost no residual adhesive in the container at the time of peeling the label, the label removal rate is faster than the conventional plastic label at the same temperature, the recycling time of the container It is to provide a heat shrinkable label that can shorten and reduce environmental pollution.

In order to achieve the above object, the present invention includes a heat shrinkable film layer and a pressure-sensitive adhesive layer having a shrinkage in the longitudinal direction or the transverse direction of 30% or more during heat treatment at 80 ° C. for 20 seconds, and is represented by Equation 1 below. Provided is a heat shrinkable label characterized by:

Equation 1

In the above formula, m0 'is the converted value of the adhesive force of the pressure-sensitive adhesive layer at room temperature (25 ° C), [(m0-m1) / m0 × 100]' is the converted value of the adhesive force temperature change rate, and ΔT 'is 80 ° C. It is a conversion value of the time when a label peels from an adherend, (eta) 'is a conversion value of the residual ratio of a label at the time of peeling after cross cut at normal temperature, and (alpha) is a proportionality constant.

The heat shrinkable label according to the present invention may be peeled off when the container with the label is immersed in hot water, hot air, or steam for 20 seconds, and is a water-soluble cleaning solution as well as using an adhesive that does not contain an additive that causes environmental pollution. It has an effect of preventing environmental pollution by using an adhesive which hardly dissolves in the. In addition, there is little residual of the adhesive during peeling has the effect of reducing the cost when recycling the container of the beverage.

Hereinafter, the present invention will be described in more detail.

The heat shrinkable film layer of the present invention is polyester, polypropylene, and polycarbonate having a longitudinal or transverse shrinkage of 30% or more, preferably at least 50% of shrinkage in at least one direction upon heat treatment at 80 ° C. for 20 seconds in hot water, hot air, or steam. It may include one or more resins selected from the group consisting of.

In particular, the polyester resin is an acid component such as terephthalic acid, isophthalic acid and naphthalenedicarboxylic acid, and ethylenediol, propanediol, butanediol, hexanediol, ethylene glycol, neopentyl glycol and 1,4-cyclohexanedimethanol It may be polyester obtained by reacting the diol component of, Preferably it is ethylene terephthalate. As a diol component, it is preferable to contain 1 or more types of diols, such as a C3-C6 propanediol, butanediol, hexanediol, and neopentylglycol, and it is especially preferable to contain neopentylglycol as 1 type of diol component. Do. Moreover, it is preferable that it is polyester which adjusted glass transition temperature (T _g ) to 55-80 degreeC.

Polyester used for the heat-shrinkable film of this invention may be used individually by 1 type, and may mix and use 2 or more types. In addition, in this invention, when polyester contains 2 or more types of acid component and / or diol component, the content rate of said acid component or diol component is poly whether or not transesterification is performed after mixing. The content rate of the acid component and diol component in the ester as a whole is shown. The same applies to the case of using two or more polyesters.

The heat-shrinkable film of the present invention can be produced as uniaxial and / or biaxial stretching, and the stretching ratio in at least one of the longitudinal and transverse directions is preferably 2 to 5 times, more preferably in the stretching ratio in at least one direction. Is preferably 3 to 4.5 times.

The heat-shrinkable film of the present invention may further include additives such as inorganic lubricants, organic lubricants, colorants, antioxidants, compatibilizers, antistatic agents, and ultraviolet absorbers for improving the activity, within the range of not impairing the action of the present invention. It may contain.

Although the thickness of the heat shrinkable film of this invention is not specifically limited, When using as a shrink film for labels, it is preferable that it is 10-200 micrometers, More preferably, it is 30-100 micrometers.

The surface of the heat-shrinkable film of the present invention may be subjected to various treatments such as corona discharge, primer treatment, plasma treatment or chemical etching in order to improve the fixing strength of the adhesive layer.

The label of the present invention includes an acrylic adhesive, a natural rubber or a synthetic rubber, or a silicone adhesive as the adhesive layer, and in particular, the peeling degree represented by the following Equation 1 is 70 to 100.

Equation 1

.
In the above formula, m0 'is the converted value of the adhesive force of the pressure-sensitive adhesive layer at room temperature (25 ℃) according to the following conversion table, [(m0-m1) / m0 × 100]' is the conversion value of the adhesive force temperature change rate according to the following conversion table , ΔT 'is the converted value of the time when the label is peeled from the adherend at 80 ℃ according to the following conversion table, η' is the conversion value of the residual ratio of the label at the time of peeling after cross-cutting at room temperature according to the following conversion table, α is Although it is a proportional constant, it is a constant which expresses the data measured by the conditions on the specific description in conversion, and has a range of 2-3. Α is 2.5 when the adherend is a glass substrate:

.

The pressure-sensitive adhesive layer used for the label of the present invention is preferably a water-insoluble acrylic pressure-sensitive adhesive, main monomers such as ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, vinyl acetate, acrylonitrile, styrene, methyl methacryl Copolymers of co-monomers such as acrylate, ethyl methacrylate, butyl methacrylate, methyl acrylate, methacrylic acid, acrylic acid, itaconic acid, hydroxy propyl methacrylate, glycidyl methacrylate, maleic anhydride Can be used.

The adhesive layer used for the label of the present invention is an additive such as an inorganic lubricant, an organic lubricant, a colorant, an antioxidant, a commercially available agent, an antistatic agent, and an ultraviolet absorber to improve the activity within a range that does not impair the action of the present invention. It may further contain, but preferably does not contain any of the additives.

Such a pressure-sensitive adhesive layer may be used in a thickness of 5 to 100㎛, preferably 10 to 40㎛, if the thickness is less than 5㎛ the adhesive force of the adhesive becomes uneven, if the thickness exceeds 100㎛ fear of adhesive layer delamination may occur The change in physical properties is severe due to the degree of curing of the pressure-sensitive adhesive, which may cause desorption of the ends, which is not preferable.

The room temperature (25 ° C.) adhesion force on the glass adherend of the adhesive layer used in the label of the present invention is 300 to 2000 gf / in according to the KS A 1107-8 test method, preferably 500 to 1200 gf / in.

The label according to the present invention may include a release layer for protecting the pressure-sensitive adhesive layer, and basically requires release property, adhesion, surface smoothness and dimensional stability, and needs to be peeled off well in the pressure-sensitive adhesive layer, so that low peeling force is required. Therefore, any material satisfying the above properties can be used without any limitation.

The label according to the present invention can be produced by printing a label directly on the heat-shrink film, but may include a print layer separately without printing directly on the heat-shrink film (see FIG. 5). The printing layer may be located between 0.5 and 15 μm thick, preferably between 1 and 8 μm thick, between the adhesive layer and the heat shrinkable film or between the heat shrinkable film and the protective layer, and may be acrylic, urethane or vinyl. Ink binders that contain shrinkage and flexibility are also available.

In addition, the label according to the present invention may further include a protective layer to protect the heat shrink film. Such a protective layer can be implemented by an overprinting method or a lamination method. The protective layer may be used in a thickness of 0.1 to 100㎛. When implemented by the over-printing method it may be preferably used in a thickness of 1 to 5㎛, acrylic, urethane, vinyl or modified resin including the same may be used (see Figure 6). In addition, when the plastic film is implemented by the laminating method, it may be preferably used in a thickness of 5 to 30 μm, and may be used as long as it is a plastic film capable of adhesion / adhesion (see FIG. 7).

Hereinafter, the present invention will be described in more detail based on the following examples. However, the following examples are only for illustrating the present invention, and the scope of the present invention is not limited thereto.

Example 1

After printing using a gravure method on the heat-shrink film (SKC SP19H 45㎛) (printing ink is acrylic solvent evaporation ink), and then bound to the laminator No. 2 unwinder, release film (SKC SG31 23㎛ The release film is bound to the first unwinder, and a re-peelable pressure-sensitive adhesive having the properties shown in Table 1 is applied to a thickness of 20 μm, and then the printing surface of the heat-shrink film bound to the second unwinder is In order to form a pressure-sensitive adhesive film to form a completed adhesive film and to obtain a label having a shape suitable for a use, the finished label was manufactured in a sheet or roll shape by Thomson's process and bonded and fixed to a glass bottle.

Example 2

It was prepared in the same manner as in Example 1 except that an adhesive of another component having physical properties as shown in Table 1 was used.

Example 3

It was prepared in the same manner as in Example 1 except that an adhesive of another component having physical properties as shown in Table 1 was used.

Comparative Example 1

As shown in Table 1, was prepared in the same manner as in Examples 1 to 3 except that the pressure-sensitive adhesive of the component having a pressure-sensitive peeling of 50 to 60 was used as the pressure-sensitive adhesive layer.

Comparative Example 2

As shown in Table 1, was prepared in the same manner as in Examples 1 to 3 except that the pressure-sensitive adhesive of the component having a pressure-sensitive peeling of 40 to 50 was used as the pressure-sensitive adhesive layer.

The physical properties and the degree of peeling of the adhesive layers used in Examples 1 to 3 and Comparative Examples 1 and 2 are summarized as follows. Each physical property measurement method is as shown in Table 2.

In particular, in order to measure the residual ratio shown in Table 2 below, after attaching a heat shrinkable clear label having a 25 mm x 100 mm area to a glass substrate, the 10 mm x 10 mm area was cut into 100 cells at 1 mm x 1 mm using a cross cutter, After attaching a tape (No. 396) manufactured by 3M Co., Ltd. on the top of the label, it was maintained for 72 hours. Then, the area of the cells which were not peeled by forcible peeling within 1 second with a force of about 6 kgf / in was obtained, divided by the total area (10 mm × 10 mm), and then expressed as a percentile value. This was carried out a total of five times to obtain the average value is shown in Table 2.

Evaluation of Heat Shrinkable Labels

(1) peelability

The labeled glass bottles of Examples 1 and 2 and Comparative Examples 1 and 2 were immersed in warm water (80 ° C.) for 20 seconds, and then the number of samples from which labels were removed was measured. Each sample was measured 20 times and the results are shown in Table 3 below.

(2) Whether the adhesive remains after peeling off the label

In the peelability test, the glass bottle from which the label was removed was collected and the removed surface was visually inspected to determine the amount of residue. Each sample was measured 20 times and rated 0-5 according to the following criteria.

Rating

0 no residue visible

1 slight residue at the end of the label

2 Residues occupying approximately 1-5% of label area

3 Residues occupying approximately 6-10% of label area

4 Residues occupy approximately 11-15% of label area

5 Residues occupy approximately 15-20% of label area

(3) Whether the adhesive component is dissolved during the washing process

The total mass of the label used in the peelability test was measured in advance, the peeled label was collected to remove moisture, the mass was measured, and then the adhesive remaining in the glass bottle was extracted with an organic solvent (MEK) to form an organic solvent ( MEK) is evaporated to determine the weight of the remaining adhesive. The remaining mass except for the sum of the mass of the peeled label and the mass of the remaining pressure-sensitive adhesive in the total mass is obtained, and then converted into mg / L based on the total amount of hot water used. Each sample was measured in total of 20 times and the results are shown in Table 3 below.

As can be seen from Tables 1 and 3, the film of Examples 1 to 3 of the present invention satisfies the adhesive peeling degree of 70 to 100, the same temperature (80 ℃) when compared with Comparative Examples 1 and 2 Has a very good peeling rate, but shows very good properties with little residual adhesive during peeling. In addition, since the pressure-sensitive adhesive and the printing layer are almost attached to the surface of the shrinked film, it has a property of preventing secondary water contamination that may occur when detached.

1 is a schematic diagram of a gravure printing press.

2 is a schematic diagram of a microgravure coater.

3 is a schematic view showing a Thompson machining process.

4 is a schematic view showing a labeling process.

5 to 7 are schematic views showing the structure of a label according to the present invention.

Claims (12)

A heat shrinkable film layer and a pressure-sensitive adhesive layer having a shrinkage in the longitudinal or transverse direction of 30% or more upon heat treatment at 80 ° C. for 20 seconds, and the adhesion peeling degree represented by Equation 1 below is 70 to 100, at room temperature (25 ° C.). The adhesive force (m0) of the pressure-sensitive adhesive layer is 160 to 1080 gf / in, and the temperature change rate [(m0-m1) / m0 × 100] of the adhesive force (m0) at room temperature and the adhesive force (m1) at 60 ° C is 42 to A heat shrinkable label, characterized in that the time at which the label is peeled off from the adherend at 80 ° C. (ΔT) is 12 to 52 seconds, and the residual ratio (η) of the label upon peeling after cross-cutting at room temperature is less than 5%: Equation 1

Where m0 'is a conversion value of the adhesive force of the adhesion layer at normal temperature (25 degreeC) according to the following conversion table, [(m0-m1) / m0 × 100] 'is a converted value of the adhesive force temperature change rate according to the following conversion table, ΔT 'is a conversion value of the time when the label is peeled from the adherend at 80 ° C according to the following conversion table, η 'is the converted value of the residual ratio of the label upon peeling after cross-cutting at room temperature according to the following conversion table. α is the proportional constant:

The method of claim 1, At least one main monomer selected from the group consisting of ethyl acrylate, butyl acrylate and 2-ethylhexyl acrylate, vinyl acetate, acrylonitrile, styrene, methyl methacrylate, ethyl methacrylate, At least one monomer selected from the group consisting of butyl methacrylate, methyl acrylate, methacrylic acid, acrylic acid, itaconic acid, hydroxy propyl methacrylate, glycidyl methacrylate and maleic anhydride. Heat shrinkable label. The method according to claim 1 or 2, A heat shrinkable label having a tack of 75 to 90. The method according to claim 1 or 2, Heat-shrinkable label, characterized in that the thickness of the adhesive layer is in the range of 5 to 100㎛. delete The method according to claim 1 or 2, Heat-shrinkable label, characterized in that the adhesive layer is water-insoluble. The method of claim 1, A heat shrinkable label further comprising a printing layer between the adhesive layer and the heat shrinkable film layer. The method of claim 7, wherein The label includes a release layer, heat-shrinkable label, characterized in that laminated in the order of the release layer, the adhesive layer, the printing layer and the heat shrink film layer. The method of claim 8, A heat shrinkable label further comprising a protective layer. The method of claim 9, A heat shrinkable label, which is laminated in the order of a release layer, an adhesive layer, a printing layer, a heat shrink film layer, and a protective layer. The method of claim 9, A heat shrinkable label, which is laminated in the order of a release layer, an adhesive layer, a heat shrink film layer, a print layer, and a protective layer. The method of claim 10 or 11, And the protective layer is formed by an overprinting method or a lamination method.

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