JP2010106143A - Easily-peelable heat-sensitive varnish and easily-peelable heat-sensitive label - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an easily-peelable heat-sensitive varnish and an easily-peelable heat-sensitive label through a stable, inexpensive method, provided that the varnish and the label show no tackiness at ordinary temperatures but exert tackiness particularly when heated so as to enable their adhesion to a glass bottle and that the label does not leave any marks after peeled off. <P>SOLUTION: The easily-peelable heat-sensitive varnish is obtained by mixing 83-92 mass% acrylic resin adhesive and 8-17 mass% acrylic resin and adding a powdery polyethylene wax in a mass ratio of 1-4% based on the total mass of the acrylic resin adhesive and the acrylic resin. The easily-peelable heat-sensitive label is obtained using the same. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a heat-sensitive adhesive label that is applied to the surface of a glass bottle. It is not sticky at room temperature, is sticky when heated and can be adhered to a glass bottle, and after peeling off the label, it is easy to leave no peeling marks. The present invention relates to a peelable thermosensitive label and an easily peelable thermosensitive varnish used therefor.

  The thermal labels for glass bottles currently on the market have strong cohesive strength of the thermal agent, so once affixed to the surface of the glass bottle, when picking to peel off, the paper substrate layer breaks between layers, causing paper to break. The paper peeling phenomenon in which only the upper layer portion of the substrate is peeled off easily occurs. Furthermore, even if it is soaked and peeled off, the adhesive layer is firmly adhered to the surface of the glass bottle, so that paper remains. In recent movements to recycle used glass bottles, they cannot be peeled off during distribution or use, and can be easily peeled off by hand from the surface after use. A label is required. It is also important that no varnish remains on the surface of the bottle after peeling.

  Many conventional thermal labels are called delayed tack. For example, a typical example is one in which a water-insoluble polymer material, a tackifier, or a chemical agent in which a solid plasticizer is dispersed or emulsified in water or the like is applied to one surface of a substrate as a sticking surface (Patent Document) 1).

The water-insoluble polymer material described above includes an ethylene-vinyl acetate copolymer (EVA).
A combination of at least one or more water-insoluble polymer compounds such as polyvinyl acetate (PVA), natural rubber, synthetic rubber, vinyl acetate-acrylate copolymer, polyester, polyurethane, etc. is used. Yes.

  The tackifier is a component for enhancing the adhesive when activated by heating. For example, a resin such as a rosin derivative, a terpene resin, a petroleum resin, a phenol resin, or a xylene resin is used. It has been.

  Furthermore, the solid plasticizer is solid at normal temperature and melts when heated above its melting point, and swells and dissolves the above water-insoluble polymer materials and tackifiers to express tackiness and adhesiveness. Let Since it does not crystallize once it has been dissolved, it can take a long time to maintain the adhesion after activation. For example, dicyclohexyl phthalate (DCHP), diphenyl phthalate, dihexyl phthalate, dihydroavilate phthalate Ethyl, dimethyl isophthalate, sucrose benzoate, ethylene glycol dibenzoate, trimethylol ethane tribenzoate, glyceride tribenzoate, pentyl tetrabenzoate, sucrose octaacetate, tricyclohexyl citrate N-cyclohexyl-P-toluenesulfone Organic compounds that are solid at room temperature, such as amides, are used.

  However, these delayed tacks partially start to be activated at a temperature of about 60 ° C. Therefore, problems such as blocking during transportation during summer days and temperature management in warehouses such as storage are necessary conditions. It was. In addition, since the adhesiveness is maintained to some extent, it is difficult to control the degree of peeling, and there is a problem that even if peeling can be done, a peeling mark remains in the container. Furthermore, the phthalic acid ester used as a solid plasticizer has become an environmental hormone-like substance, and there is also a problem that there is a concern about the influence on organisms.

There has also been proposed an easily peelable thermosensitive label that is not sticky at room temperature, in particular, sticky when heated and can be adhered to PET bottles, glass bottles, etc., and no peeling marks remain after the label is peeled off. (Patent Document 2).

  The heat-sensitive adhesive layer is composed of a resin-based layer of ethylene-vinyl acetate copolymer, and the vinyl acetate content in the ethylene-vinyl acetate copolymer is in the range of 5% to 30%. It is possible to realize an easily peelable thermosensitive label in which no peeling trace remains. Furthermore, it is also possible to adjust the peeling force by adding a surfactant or spherical polyethylene wax (Patent Documents 3 and 4).

However, in this method, the lower limit of the coating amount is as large as about 10 g / m ² in order to develop adhesiveness, and in order to secure the coating amount in the coating process, it is necessary to repeat coating and drying twice or more. The efficiency of certain processes is low. Moreover, a large amount of heat is required for drying, and troubles such as blocking due to insufficient drying are likely to occur. Furthermore, it is also disadvantageous in terms of material costs.
JP 2002-6750 A JP 2006-106234 A JP 2006-53454 A JP 2006-243315 A

  Providing an easily peelable thermosensitive label in a stable and inexpensive manner that does not stick at room temperature, in particular, is sticky when heated and can be adhered to a glass bottle, and after the label is peeled off, no peeling marks remain. It is a problem.

  The invention of claim 1 is obtained by mixing 83 to 92% by mass of an acrylic resin-based pressure-sensitive adhesive and 8 to 17% by mass of an acrylic resin, and adding 1 to 4% of powdered polyethylene wax of the mass ratio. This is an easily peelable heat-sensitive varnish.

The invention of claim 2 has a display layer composed of a printed pattern layer, a decorative aluminum vapor deposition layer or a hologram layer on one side of the substrate, and acrylic resin adhesives 83 to 92 on the other side of the substrate. Applying 0.5 to 3.0 g / m ^{2 of} an easily peelable heat-sensitive varnish mixed with 8% to 17% by mass of acrylic resin and 8 to 17% by mass of acrylic resin, and added with powdered polyethylene wax of 1 to 4% of the mass ratio. It is an easily peelable thermosensitive label characterized by being formed.

  By using a composition in which acrylic resin and powdered polyethylene wax are added to an acrylic resin-based adhesive as the heat-sensitive varnish to be provided on the back surface of the substrate, there is no adhesive at room temperature. An easily peelable heat-sensitive label that can be bonded and does not leave a peeling mark after the label is peeled off can be produced. In particular, since a label can be prepared with a low coating amount of a heat-sensitive varnish, an easily peelable heat-sensitive label can be provided by a cheaper and more stable method than before. Specifically, the heat-sensitive varnish can express the required performance with a low coating amount, thereby shortening the coating process and reducing the load and stabilizing the drying process.

  In addition, since this label is not sticky at room temperature, it is not necessary to use release paper, so it is possible to increase the length of winding with the same diameter and reduce the amount of waste when winding the label. The effect of being able to do etc. is also mentioned.

  An example of an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional explanatory view showing a layer structure of an easily peelable thermosensitive label as an example of the present invention.

As shown in FIG. 1, the easily peelable thermosensitive label of the present invention has a display layer 2 on one side of a substrate 3 and an easily peelable thermosensitive varnish layer 9 on the other surface of the substrate. It is a label 1, Comprising: This easily peelable thermosensitive varnish layer 9 consists of a composition which added the acrylic resin and powdered polyethylene wax to the acrylic resin-type adhesive, and the application quantity is 0.5-3.0 g / m < ² >. It is an easily peelable thermosensitive label.

  An example of a typical production process of the easily peelable heat-sensitive label of the present invention is as follows. An aluminum vapor-deposited paper 7 and a PET film 4 are bonded together with a dry laminate adhesive 8, and the pattern layer 6 and The OP varnish layer 5 is printed, and the thermal varnish 9 is applied to the PET surface with a coating machine.

  The display layer 2 is a layer that becomes an outer surface when a label is attached to a glass bottle, and shows a pattern layer 6 and an OP varnish layer 5 provided on the substrate 3. The pattern layer includes, in addition to the ink pattern, decoration by aluminum foil or aluminum vapor deposition, hologram processing, and the like. The OP varnish layer is a transparent layer provided as necessary for improving surface resistance and adjusting gloss.

  The substrate 3 is not particularly limited as long as the display layer 2 and the heat-sensitive varnish layer 9 can be laminated and the tensile strength is larger than the adhesive strength between the container and the label.

  Examples of the film 4 constituting the substrate 3 include polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN); polyolefin resins such as polyethylene and polypropylene; styrene-butadiene Examples thereof include polystyrene resins such as copolymers; films made of polyvinyl chloride resins, polyvinylidene chloride resins and the like, polyamide films, and the like.

  As the film 4 of the label that is attached by winding or attached by pressurization, an unstretched film or a biaxially stretched film, particularly a biaxially stretched polypropylene film (OPP) and a PET film are used.

  The thickness of the film can be appropriately selected within a range that does not impair the mechanical strength, the handleability of the label, and the like, but is preferably about 9 μm to 100 μm. When the thickness of these films is less than the above-mentioned numerical value, the tensile strength is small, and therefore, the label may be broken when the label is peeled off. On the other hand, if the thickness exceeds the above values, the film will be too stiff, making it difficult to label, and heat from the heating drum during labeling will be difficult to transfer, resulting in a decrease in labeling speed. Occur. Further, the unnecessarily large thickness is not economical from the viewpoint of material cost and heating heat quantity.

As the paper 7 constituting the substrate 3, for example, high-quality paper, craft paper, single-sided art paper, double-sided art paper, aluminum vapor-deposited paper, etc. can be used, and the paper basis weight is 50 g / m ^{2 to} 200 g / m. ² is desirable. The picture layer 6 is a layer in which a product name, an illustration, handling precautions, and the like are printed by a known method. The printing ink used for forming the pattern layer 6 is, for example, an ink mainly composed of an acrylic resin, a polyurethane resin, or a mixture thereof so as not to be damaged by heat when the adhesive layer 9 is activated. It is preferable to use an ink in consideration of the heat resistance.

In order to improve the adhesion of the pattern layer 6 to the aluminum vapor-deposited paper 7, a known primer such as an acrylic primer, a polyester primer, an isocyanate primer (two-component mixed primer, etc.) is used between the two layers. A primer coat layer may be provided.

  The paper 7 constituting the substrate 3 and the film 4 are bonded by a known bonding method, for example, a dry lamination method, a hot melt lamination method, a wet lamination method, or a non-solvent dry lamination method.

  The dry lamination method is a method in which an adhesive is applied on one base material layer and bonded to the other base material, and the three sections of the coating part, the drying device, and the nip roller part are unwound and taken up. And a tension control system.

  For the coating part, the gravure roll coating method is common because it is necessary to ensure the stability of the coating amount. When high coating amount and smoothness of the coated surface are required, the gravure reverse roll coating method is adopted. Yes.

  As the adhesive used in the dry lamination method, polyurethane, polyacrylic, polyester, epoxy, polyvinyl acetate, cellulose, and other laminating adhesives can be generally used.

  As the adhesive for lamination, a solvent type adhesive or a solventless type adhesive is used. However, when a solventless type adhesive is used, a drying device is not necessary, and it is particularly called a non-solvent dry lamination method. It is out.

  In the hot melt lamination method, a hot melt adhesive composed of a heat-melted ethylene-vinyl acetate copolymer (EVA), a wax, a tackifier, and the like is applied on one base material layer, and immediately, the other base material is applied. Is a method of pasting together.

  In the wet lamination method, a water-soluble adhesive is applied on one base material layer, and the adhesive is laminated with the other base material in a wet state. It is a method.

  These bonding adhesives and bonding methods can be appropriately selected depending on the substrates to be bonded.

  Next, as the heat-sensitive varnish 9, a composition obtained by adding an acrylic resin and powdered polyethylene wax to an acrylic resin adhesive is used.

  As the main component of the thermal varnish 9, an acrylic resin-based adhesive (for example, ARONTAC TT1214 manufactured by Toagosei Co., Ltd.) is used. However, if the varnish is used alone, the thermal varnish surface of the label is poorly slipped and the labeling suitability is deteriorated. Therefore, an acrylic resin is added, and polyethylene wax is added to improve the peelability.

  Examples of the monomer component constituting the acrylic resin include (meth) acrylic acid such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. Alkyl ester; carboxyl group-containing polymerizable unsaturated compounds such as (meth) acrylic acid, crotonic acid, itaconic acid, fumaric acid and maleic acid, or anhydrides thereof. Furthermore, if necessary, hydroxyl group-containing (meth) acrylic acid ester such as 2-hydroxymethyl (meth) acrylate, (meth) acrylic acid cycloalkyl ester, (meth) acrylic acid amide derivative, (meth) acrylic acid dialkyl Functional group-containing (meth) acrylic acid esters such as aminoalkyl esters; Styrenic compounds such as styrene, vinyltoluene and α-methylstyrene; Vinyl esters such as vinyl acetate and vinyl propionate; Halogenation such as vinyl chloride Vinyl; vinyl ethers such as methyl vinyl ether; cyano group-containing vinyl compounds such as (meth) acrylonitrile; polymerizable unsaturated compounds such as olefins and dienes such as ethylene and propylene can also be used as monomer components.

  As a preferable component composition of the heat-sensitive varnish, the ratio of the acrylic resin-based pressure-sensitive adhesive to the acrylic resin is in the range of 83/17 to 92/8 by mass ratio, and further added to the mixture of the acrylic resin-based pressure-sensitive adhesive and the acrylic resin. The ratio of the powdered polyethylene wax is preferably 1% to 4% by mass ratio.

  When the amount of the acrylic resin as a component for improving the slipping property is less than 8% of the total amount of the acrylic resin-based pressure-sensitive adhesive and the acrylic resin, the improvement of the slipping property is insufficient, and when it exceeds 17% It becomes excessive.

  When the amount of the powdered polyethylene wax as a component for improving the peelability is less than 1% with respect to the total amount of the acrylic resin-based pressure-sensitive adhesive and the acrylic resin, there is a peeling mark when peeling from the glass bottle. If the remaining amount is 4% or more, the adhesive strength to the glass bottle is weakened, and the risk of peeling or dropping during use of the label increases.

  The basic composition of the heat-sensitive varnish used in the easily peelable heat-sensitive label of the present invention is as described above, but it is also possible to use the following known additives in combination as required to improve the characteristics.

  There is a method of adding a slip agent for the purpose of preventing blocking. However, if excessively added, the adhesive strength is reduced, and therefore the addition amount is preferably about 2% or less. As the slip agent, generally known hydrocarbon lubricants, fatty acid / alcohol lubricants, fatty acid amide lubricants, metal soap lubricants and ester lubricants are used. Furthermore, a tackifier (rosin derivative, terpene resin, petroleum resin, phenol resin, xylene resin, acrylic, rubber, etc.) can be added to supplement the adhesive strength.

The coating amount of the heat-sensitive varnish necessary for the easily peelable heat-sensitive label of the present invention is in the range of 0.5 g / m ² to 3.0 g / m ² .

If the coating amount of the thermal varnish is less than 0.5 g / m ² , the adhesive strength between the label and the glass bottle is low, and adhesion unevenness is likely to occur, causing the label to turn over during use, or causing peeling or dropping in harsh environments. There is a case. On the other hand, when the coating amount is more than 3.0 g / m ^{2, a} phenomenon (peeling trace) that the thermal varnish remains in the glass bottle when the label is peeled off from the glass bottle occurs. Leaving the peel marks is inconvenient for recycling glass bottles and may cause problems during disposal. The coating amount of the heat-sensitive varnish is desirably less occurrence of unevenness and peeling trace of the adhesive in particular in the range from 1.0 g / m ² of 2.5 g / m ^2.

  As a coating method of the thermal varnish 9, known gravure coating such as natural gravure coating, reverse gravure coating, gravure offset coating, roll coating such as natural roll coating and reverse roll coating, knife coating, kiss coating, fountain coating, etc. A coating method can be used.

In the application of the thermal varnish used in the thermal label of the present invention, it is assumed that the coating amount before drying is about 10 g / m ² or less in view of the coating amount, printing of a pattern and coating of a dry laminate adhesive Gravure coating is preferred because the same printer can be used. It is also possible to perform known treatments such as corona discharge treatment, plasma treatment, flame treatment and the like for enhancing the adhesion to the substrate as necessary.

  As a drying method of the heat-sensitive varnish 9, hot air drying is fundamental, but when the heat-sensitive varnish is aqueous, combined use of auxiliary means such as far-infrared drying and near-infrared drying is also effective.

  Hereinafter, a specific embodiment will be described in detail with reference to FIG.

<Example 1>
Aluminum vapor-deposited paper 7 having a basis weight of 60 g / m ² and polyethylene terephthalate (PET) film 4 having a thickness of 12 μm were bonded together by dry lamination using urethane adhesive 8. Next, the pattern 6 and OP varnish 5 for improving abrasion resistance and blocking resistance were printed on the surface of the aluminum vapor-deposited paper 7 with a gravure printing machine.

Furthermore, after drying the thermosensitive varnish 9 prepared at a ratio of acrylic resin adhesive / acrylic resin / powdered PE wax = 92/8/1 to the PET surface with a gravure coating machine, the coating amount is 0.5 g / m. ^The coating was dried to be ² . Alontac TT1214 (trade name) manufactured by Toagosei Co., Ltd. was used as the acrylic resin adhesive. Then, it was slit to a predetermined width to obtain a thermosensitive label.

<Example 2>
A thermal label was obtained in the same manner as in Example 1 except that the coating amount after drying of the thermal varnish 9 was 1.0 g / m ² .

<Example 3>
A thermal label was obtained in the same manner as in Example 1 except that the coating amount after drying of the thermal varnish 9 was 2.0 g / m ² .

<Example 4>
A thermal label was obtained in the same manner as in Example 1 except that the coating amount after drying of the thermal varnish 9 was 2.5 g / m ² .

<Example 5>
A thermal label was obtained in the same manner as in Example 1 except that the coating amount after drying of the thermal varnish 9 was 3.0 g / m ² .

<Comparative Example 1>
A thermal label was obtained in the same manner as in Example 1 except that the coating amount after drying of the thermal varnish 9 was 0.3 g / m ² .

<Comparative example 2>
A thermal label was obtained in the same manner as in Example 1 except that the coating amount after drying of the thermal varnish 9 was 3.5 g / m ² .

<Comparative Example 3>
Except that the composition of the thermal varnish 9 is EVA resin / DCHP / surfactant / spherical polyethylene wax = 92/6/1/1 and the coating amount after drying is 9.0 g / m ² , the same as in Example 1. Thus, a thermosensitive label having almost the same performance as the conventional product was obtained.

The label shown above was labeled on a glass bottle having a diameter of 50 mm and a height of 100 mm under the following conditions, and the peelability was evaluated. There was no particular problem with labeling suitability in any of the samples. The labeling conditions are a drum temperature of 115 ° C., a hot air temperature of 350 ° C., and a labeling speed of 100 lines / minute.

  The labeled glass bottle was stored under the following conditions, and then the label was peeled by hand to evaluate the peelability. Storage conditions: 1 day later and 20 ° C 3 months, 40 ° C 75% 3 months.

  The evaluation results are as shown in Table 1.

評価結果からは、本発明の易剥離性感熱ラベルでは感熱ニスの塗布量が０．５ｇ／ｍ²から３．０ｇ／ｍ²の範囲において、良好な剥離強度と剥離痕なしの結果が得られた。とくに感熱ニスの塗布量が１．０ｇ／ｍ²から２．５ｇ／ｍ²の範囲において剥離強度が最適な範囲にあり、かつ、剥離痕がまったく残らないという理想的な結果となった。

From the evaluation results, in the easily peelable thermosensitive label of the present invention, in the range where the coating amount of the heat sensitive varnish is in the range of 0.5 g / m ² to 3.0 g / m ² , good peel strength and no peeling marks are obtained. It was. In particular, an ideal result was obtained in which the peel strength was in the optimum range when the coating amount of the heat-sensitive varnish was in the range of 1.0 g / m ² to 2.5 g / m ² , and no peeling marks remained.

In the heat-sensitive label of Comparative Example 1, which had a heat-sensitive varnish coating amount of 0.3 g / m ² , which was small compared to the examples, peeling marks were not seen, but turning-up occurred due to weak adhesion. In the heat-sensitive label of Comparative Example 2 in which the coating amount of the heat-sensitive varnish was 3.5 g / m ² , which was large compared to the examples, the peel strength was in an appropriate range, but peeling marks were observed. When compared with the conventional product of Comparative Example 3, a heat-sensitive label having a peelability equivalent to both the peel strength and the peel mark was obtained with a heat-sensitive varnish coating amount of 1/3 or less of the conventional product.

From the above results, it was confirmed that the heat-sensitive label of the present invention was superior to conventional ones in terms of materials, processes, and quality in obtaining equivalent peeling performance. That is, since the conventional product requires a coating amount of 9 g / m ² or more for the thermal varnish, the coating amount is larger than that of the thermal label of the present invention, the number of coating processes is large, and the quality variation such as the risk of blocking is large. On the other hand, the heat-sensitive label of the present invention has the effect of reducing the material cost, the number of steps, and the risk of blocking the heat-sensitive varnish by reducing the amount of heat-sensitive varnish applied.

  Moreover, according to the experiment which changed the component composition ratio of the heat sensitive varnish about the item shown in Table 1, the ratio of the following acrylic resin adhesive / acrylic resin was 92/8 to 83/17 by weight ratio. In the range of 1 to 4% by mass of powdered PE wax with respect to the range and the total of the acrylic resin-based pressure-sensitive adhesive / acrylic resin, the evaluation results for peelability were the same as in the examples.

It is sectional explanatory drawing which shows the layer structure of the easily peelable thermosensitive label of an example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Easy peelable thermal label 2 ... Display layer 3 ... Base material 4 ... Film 5 ... OP varnish layer 6 ... Pattern layer 7 ... Aluminum vapor deposition paper 8 ... Dry laminate adhesive 9 ... Easy peelable heat sensitive varnish layer

Claims (2)

  Easy peeling, characterized by mixing 83 to 92% by mass of acrylic resin adhesive and 8 to 17% by mass of acrylic resin and adding 1 to 4% of powdered polyethylene wax of the mass ratio Sexual heat sensitive varnish. It has a display layer consisting of a printed pattern layer, a decorative aluminum vapor deposition layer or a hologram layer on one side of the substrate, and acrylic resin adhesive 83-92% by mass on the other side of the substrate, acrylic resin 8-17 mass% is mixed, 0.5-3.0 g / m < ² > apply | coat the easily peelable heat-sensitive varnish which added the powdery polyethylene wax of 1-4 mass of the mass ratio, It is characterized by the above-mentioned. Easy-to-release heat-sensitive label.

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