JP2000355681A - Heat seal type adhesive label - Google Patents

Abstract

(57) Abstract: A heat-sealing adhesive label that does not require release paper, and is suitable for labeling cylindrical containers of soft drinks, alcoholic beverages, pharmaceuticals, foods, etc., and deformable containers made of plastic materials. It is to provide a mold adhesive label. The present invention relates to a heat-sealable adhesive label obtained by applying a heat-sealable adhesive to the back surface of a front substrate, and to a J Tappi paper pulp test method No. 1 for the back surface of the front substrate. Smoothness according to No. 5 is 150 seconds or more, or a smoothing layer is provided on the back surface of the surface substrate, and the surface of the smoothing layer is subjected to J Tappi paper pulp test method No.
A heat-sealable adhesive label having a smoothness according to No. 5 of 150 seconds or more and obtained by applying a heat-sealable adhesive on the smoothing layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sealable adhesive label provided with a heat-sealable adhesive on one surface of a surface substrate. More specifically, the present invention relates to a heat-sealable adhesive label suitable for labeling cylindrical containers for soft drinks, alcoholic beverages, pharmaceuticals, foods, and the like and deformable containers made of plastic materials.

[0002]

2. Description of the Related Art Conventionally, label sticking to glass bottles of soft drinks, alcoholic beverages, pharmaceuticals, foods, etc. is performed by directly applying a water-soluble adhesive such as casein or starch to the back surface of a label base material.
A method of attaching using an automatic labeler or the like, or a method of attaching a general adhesive label in which a top paper, an adhesive layer, and a release sheet are sequentially laminated by an automatic labeler or the like is adopted.

However, when a water-soluble adhesive is applied to the back surface of a label substrate for labeling, the label is wrinkled or curled because the water-soluble adhesive is applied directly to the back surface of the substrate. Therefore, there was a problem that labeling was poor and the appearance was impaired. In the case of an adhesive label, an unnecessary release sheet is generated after labeling, which is not preferable from the viewpoint of resource saving. Therefore, in recent years, delayed adhesive labels and heat-seal adhesive labels that do not require a release sheet have attracted attention.

[0004]

The delayed-type adhesive label and the heat-sealable adhesive label each have a delayed-type adhesive and a heat-sealable adhesive laminated on one side of a label substrate, respectively. It expresses sex. The difference between the two is that the delayed adhesive label develops the desired adhesiveness only by heating, and the adhesiveness lasts for several hours.For example, a thermoplastic resin that develops adhesiveness by heating, a tackifying resin, and a solid A delayed-type pressure-sensitive adhesive layer containing a plasticizer as a main component is provided on one surface of the surface substrate.

On the other hand, a heat-sealable adhesive label develops adhesiveness by heating, but loses adhesiveness instantly when the label cools. For example, a thermoplastic resin which develops adhesiveness by heating, a tackifier, A heat seal adhesive layer mainly composed of resin and wax is provided on one surface of the surface substrate.

Accordingly, applicable labelers are different from each other, and a delayed adhesive label requires a heating device for heating the label and a simple sticking device for sticking the label to the container, whereas a heat seal type adhesive label is required. Adhesive labels include
As described above, in order to supplement the adhesive performance of the heat-sealable adhesive having poor adhesion, in order to physically anchor the adhesive layer to an adherend, a heating device having a pressure-bonding function simultaneously with label heating is required. Required.

For this reason, the labeler of the heat-sealable adhesive label usually has a high temperature of 100.degree.
^{About 2} high pressures are simultaneously applied to the label from the hot plate.
Therefore, usable adherends are limited in form, material, and the like, and in particular, the form is limited to a flat surface, and is a cylindrical type such as a container for soft drinks, alcoholic beverages, medicines, foods, and the like, which is a field of application of the present invention. This is not possible with containers made of plastic or plastic containers that deform under pressure.

On the other hand, the delayed-type pressure-sensitive adhesive label has a long good adhesive duration as described above, so that the applicable labeler has a wide range, but the pressure-sensitive adhesive composition causes
There are restrictions on the shelf life of the label and the application container. That is, a solidified plasticizer such as dicyclohexyl phthalate, which is generally represented as an essential component, is pulverized to about several microns into the delayed-type pressure-sensitive adhesive. This solid plasticizer is melted by heating, plasticizes the thermoplastic resin, and develops adhesiveness, but recrystallizes (solidifies) over time. For this reason, the transparent pressure-sensitive adhesive layer becomes opaque (white solidified) with recrystallization of the solid plasticizer at the time of melting, and the tackiness is lost. Therefore, a label that requires transparency or a container such as a polyethylene container is used. In the case of a product or the like in which the contents are extruded by being deformed, if the container is deformed (squeezed), the label is peeled off, so that it is not applicable.

Although there is no problem immediately after the delayed pressure-sensitive adhesive is applied to the label substrate, when the label before use is stored for a long period of time, solid plasticizer crystals precipitate on the outermost surface of the pressure-sensitive adhesive applied surface. Although the cause is unknown, it is considered that the crystal of the solid plasticizer is larger than the particle diameter of the solid plasticizer used by pulverizing at the time of label production and the crystal grows. Thereby, at the time of printing, a stain is generated on a paper roll or the like of a printing press, or crystals of the solid plasticizer adhere to a printing surface,
Printing failure sometimes occurred.

The present invention is directed to a heat-sealable adhesive label which does not require a release paper for the above-described reasons, and is used for labeling cylindrical containers of soft drinks, alcoholic beverages, pharmaceuticals, foods, etc., and deformable containers made of plastic materials. To provide a heat-sealable adhesive label suitable for the application.

[0011]

In light of this situation, the present inventors first paid attention to the composition of the delayed adhesive.
In other words, we studied that the solid plasticizer that melted when using a delayed-type adhesive label recrystallized over time and lost its adhesiveness, and that the solid plasticizer crystal was precipitated when the label before use was stored for a long time. .

As a result, there is a difference in the compatibility with the thermoplastic resin depending on the type and particle size of the solid plasticizer to be used. Although a difference is observed in the time until the above-mentioned phenomenon occurs, as long as the solid plasticizer is used, In most cases, loss of tackiness over time or precipitation of crystals occurred, and this could not be prevented. This solid plasticizer is an essential component for plasticizing a thermoplastic resin and is indispensable. Therefore, it was judged that quality deterioration over time was inevitable in delayed adhesives.

Next, the present inventors focused on the heat-sealable adhesive and conducted intensive research. Generally, the heat-sealable adhesive label has a temperature of the heat-sealable adhesive layer of 100.
Heat to more than ℃ and paste. Usually 10kg / cm
^Since it can be pasted by applying a high pressure of about ^2, it is hardly affected by adhesiveness, but like glass bottles and deformed containers,
In the case of an adherend that cannot be applied under high pressure, it is applied at low pressure, and is thus affected by adhesiveness. Therefore, the influence of the adhesiveness when applying at low pressure was investigated in further detail.

As a result, the heat-sealable adhesive 100
It was found that the adhesiveness at ° C. largely depends on the thickness of the heat-sealable adhesive layer, which is a major factor in quality fluctuation. In particular, when a label having an uneven thickness of the heat-sealable adhesive layer is attached to a deformable container, the thin portion of the adhesive layer does not adhere to the container, and the label floats and swells, or the edge of the label is not adhered. The part peels off.

The reason for this is that, in a general adhesive label in which a top paper, an adhesive layer, and a release sheet are sequentially laminated, the attaching operation is performed at room temperature or low temperature, and the adhesive layer at that time has a high viscosity, It is also hardly affected by the thickness of the pressure-sensitive adhesive layer because of its high property. However, in the heat-sealable adhesive, the attaching operation is performed at about 100 ° C., and the heat-sealable adhesive at that time has a low viscosity, and the adhesiveness is in a state lower than the adhesiveness of a general adhesive label. It is presumed that it is very susceptible to the influence of the thickness of the heat seal type adhesive layer.

In order to overcome this phenomenon, the present inventors have conducted further intensive studies. As a result, the adhesion of the heat-sealable adhesive label was determined by the smoothness of the base paper before the heat-sealable adhesive layer was provided. It was found that sex variation could be eliminated.

That is, this phenomenon naturally occurs when the adhesive layer is provided on a base paper surface having low smoothness by using a coating method for making the surface of the heat seal type adhesive layer a smooth surface. Even if the adhesive layer is provided with an adhesive layer using a coating method that does not cause unevenness in the thickness of the adhesive layer, and the application method that does not cause unevenness in the thickness of the adhesive layer, the operation of attaching the heat-sealable adhesive label is not performed. When heated to 100 ℃ to be performed, the surface of the adhesive is affected by unevenness reflecting the low smoothness of the base paper surface, the viscosity of the heat-sealable adhesive is partially reduced by heating, As a result of increasing the smoothness of the surface of the adhesive due to the leveling effect, the thickness of the adhesive layer becomes uneven.

Therefore, the present inventors have found that the thickness unevenness of the heat seal type adhesive can be prevented by setting the smoothness of the base paper before providing the heat seal type adhesive layer to 150 seconds or more. Was completed. The smoothness referred to in the present invention is defined by the JAPAN TAPPI Paper Pulp Test Method No. 5 is an Oken-type smoothness described in 5. The present invention relates to a heat-sealable adhesive label obtained by applying a heat-sealable adhesive to the back surface of a front substrate, and to a J Tappi paper pulp test method No. 1 for the back surface of the front substrate. A heat-sealable adhesive label, wherein the smoothness according to No. 5 is 150 seconds or more.

Further, a smoothing layer mainly composed of a synthetic and / or natural polymer having a film-forming property is provided on the base paper surface before the heat-sealable adhesive layer is provided, or By providing a smoothing layer having a synthetic and / or natural polymer as a main component and having a smoothness of 150 seconds or more on the surface of the smoothing layer and providing a heat-sealable adhesive layer, Unevenness could be prevented. Furthermore, it has been found that the provision of the middle smoothing layer improves the anchoring property of the heat-sealable adhesive layer, thereby obtaining a more excellent heat-sealable adhesive label. The present invention provides a smoothing layer on the back surface of a surface substrate,
Tappi paper pulp test method no. A heat-sealable adhesive label having a smoothness according to No. 5 of 150 seconds or more and obtained by applying a heat-sealable adhesive on the smoothing layer. The smoothing layer preferably contains a synthetic and / or natural polymer having film forming properties as a main component, and the smoothing layer may contain an organic or inorganic pigment.

[0020]

DETAILED DESCRIPTION OF THE INVENTION As described above, the present invention relates to the production of a heat-sealable adhesive label having a heat-sealable adhesive layer provided on one surface of a surface substrate, and to the application of the heat-sealable adhesive to the surface substrate. After the smoothness of the surface is 150 seconds or more,
To provide a heat-sealable adhesive layer, or, between the heat-sealable adhesive layer and the surface substrate, to provide a smoothing layer, and after the smoothness of the smoothing layer is 150 seconds or more, This is to provide a heat seal type adhesive layer. When the smoothness exceeds 5000 seconds, not only the desired effect is saturated, but also the curl of the manufactured heat-sealable adhesive label is deteriorated, and the attaching operation becomes difficult. A range of 150 to 5000 seconds is preferable because adverse effects such as reduction may occur.

Examples of the material of the surface substrate include papers such as printing paper (for example, art paper, coated paper, cast coated paper, finely coated paper, high quality paper, medium quality paper, recycled paper, impregnated paper, neutral paper, etc.). Paper, etc.), synthetic papers, nonwoven fabrics, woven fabrics, and sheets obtained by appropriately laminating them, and the like. When used in a hot plate heating type high-speed labeler, a substrate excellent in heat resistance is preferable. Of course, the pressure-sensitive recording layer, the thermal transfer image-receiving layer, the heat-sensitive adhesive layer,
Various recording / printing layers such as an ink jet recording layer and a pigment coating layer may be provided. When used as a label, printability and the like are required. In particular, when used as a label to be attached to a glass bottle containing a liquid such as soft drink, liquor, or a medicine bottle, it is preferable to use a substrate having excellent water resistance.

However, the back surface of the front substrate (the surface on which the heat-sealable adhesive layer is formed) must have a smoothness of 150 seconds or more, preferably 150 to 5000 seconds. For example,
When the smoothness is less than 150 seconds, the smoothness may be increased by a smoothing device such as a machine calender, a super calender, a gloss calender, or a soft nip calender.

When a smoothing layer is formed on the back surface of the front substrate, the smoothing layer is not particularly limited as long as its surface has a smoothness of 150 seconds or more. Natural polymers are preferred materials because of their film-forming properties. Specifically, polyvinyl alcohols such as completely (partially) saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, oxidized starch, acetylated starch, phosphated starch and the like. Starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, diisobutylene-maleic anhydride copolymer salt, styrene-maleic anhydride copolymer salt, ethylene- (meth) acrylic acid copolymer salt Styrene-butadiene latex, polyester / polyurethane latex, acrylic latex, and the like.

The smoothing layer may contain a pigment. For example, known inorganic pigments and organic pigments such as kaolin, calcined kaolin, heavy calcium carbonate, light calcium carbonate, aluminum hydroxide, titanium oxide, magnesium carbonate, diatomaceous earth, amorphous silica, hollow or non-hollow plastic pigment, etc. Can be Further, in the coating liquid for the smoothing layer, auxiliaries such as a dispersant, a lubricant, an antifoaming agent, a coloring agent, a preservative, an ultraviolet absorber, and a waterproofing agent can be appropriately compounded. The coating amount of the smoothing layer is not particularly limited,
For economically poor exceeds 30 g / m ^2, preferably from 1 to 20 g / m ² approximately. The smoothing layer may be formed by a method of coating the above components with a coating liquid or a method of melting and extrusion coating. Also,
After coating the smoothing layer, the smoothness can be increased by a smoothing processing device such as a super calender or a soft nip calender.

The composition of the heat seal type adhesive used in the present invention is not particularly limited. For example, a heat seal type adhesive composed of a thermoplastic resin, a tackifier, a wax or the like can be used.

As the thermoplastic resin, for example, ethylene-
Vinyl acetate copolymer, ethylene-methyl methacrylate,
Ethylene-ethylene copolymers such as ethyl acrylate,
Styrene-butadiene-styrene copolymer, styrene-
Thermoplastic elastomers such as isoprene-styrene copolymers; olefin polymers such as polyethylene, polypropylene and amorphous polyalphaolefin; and a glass transition point of about −30 ° C. to about 50 ° C. and a molecular weight of several millions. To about several hundred million.

By the way, when the glass transition point is lower than -30 ° C., the adhesive layer becomes tacky and a release sheet is required. On the other hand, when the glass transition point exceeds 50 ° C., the adhesive layer at the time of heating is too hard, and the adhesiveness is insufficient. On the other hand, if the molecular weight is too low, the cohesive force of the adhesive layer will decrease, and the adhesiveness will be insufficient. Conversely, if the molecular weight is too high, the adhesive layer at the time of heating will be too hard, and the adhesiveness will be insufficient. These thermoplastic resins can be used alone or in combination of two or more.

Examples of the tackifying resin include rosin, polymerized rosin, disproportionated rosin and its derivatives, phenol-modified resins such as polyterpene resins, terpene phenols, rosin phenols, alkylphenol resins, cumarone-indene resins, xylene resins, and aliphatic resins. Examples include hydrocarbon resins, alicyclic hydrocarbon resins, aromatic hydrocarbon resins and hydrogenated products thereof, styrene resins, vinyl toluene-α-methylstyrene copolymers, and the softening point is about 100 ° C. to 170 ° C. Can be applied. By the way, the softening point is 1
If the temperature is lower than 00 ° C., problems such as reduced blocking of the label occur, and if it is higher than 170 ° C., the adhesiveness at the time of heating tends to decrease. These tackifying resins can be used alone or in combination of two or more.

As the wax, for example, petroleum wax such as paraffin wax and micro wax and synthetic wax such as polyethylene wax and polypropylene wax are used.

The mixing ratio of the thermoplastic resin, the tackifier and the wax is preferably about 20 to 60% by weight, about 20 to 60% by weight, and about 20 to 60% by weight, respectively. It is appropriately adjusted depending on the characteristics of each label, such as the type of the wearing body and the prevention of blocking.

In addition to these, various auxiliaries such as an antioxidant and a filler can be used in combination. As an antioxidant, phenol-based, thioether-based, and phosphite-based are used alone or in combination, and as a filler, calcium carbonate, clay, talc, barium sulfate,
Zinc oxide, magnesium oxide, hydrous silicic acid, silicic anhydride and the like can be mentioned.

The amount of the heat-sealable adhesive applied is preferably 5 to 30 g / m ² in terms of dry weight. More preferably, it is 8 to 15 g / m ² . By the way, the application amount is 5 g /
If it is less than m ² , sufficient adhesiveness cannot be obtained when used as a label. On the other hand, if it exceeds 30 g / m ² , the adhesiveness obtained will be saturated, which is not economically preferable.

As a method of applying the heat seal type adhesive on the substrate or the smoothing layer, a general coater equipped with a heating and heat retaining device can be applied, and a reverse roll coater, a gravure roll can be used as a coater head. Coater,
And the like, and various coating devices such as a resin extrusion type die coater and a lip coater.

The heat-sealable adhesive label is used by performing printing or the like on the surface of a base material and continuously affixing it by a labeler or the like provided with a heating device. Even if pasted and used in cylindrical containers such as glass bottles, which had problems so far, and squeeze bottles made of polyethylene and other materials such as ketchup and eye drops,
Applicable enough.

[0035]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but it is needless to say that the present invention is not limited to these examples. In the examples, parts and% indicate "parts by weight" and "% by weight" unless otherwise specified.

Example 1 A single-sided art paper (trade name: Kanto single-sided, manufactured by Oji Paper Co., Ltd.) having a surface area of 84.9 g / m ² was subjected to a supercalender treatment, and the smoothness of the base paper was adjusted to 250 seconds. Then, a heat-sealable adhesive (trade name: Toyomelt BL-8001, manufactured by Toyo Petrolite Co., Ltd.) was applied to the base paper surface of the art paper by a dry weight of 20 using a pan-feed type roll coater.
g / m ² to obtain a heat-sealable adhesive label.

Example 2 A cast calendered paper (trade name: Mirror Cast Gold, manufactured by Oji Paper Co., Ltd.) having a surface area of 84.9 g / m ² was subjected to a super calender treatment, and the smoothness of the base paper surface was set to 180 seconds. Then, a heat-sealable adhesive label was produced in the same manner as in Example 1.

Example 3 As a pigment, 100 parts of kaolin (trade name: HT clay, manufactured by Engelhard) and an acrylic dispersion (Poise 520,
2.5 parts of Kao (made by Kao) and 100 parts of water were mixed and dispersed with a Coreless disperser. In the dispersion, oxidized starch (trade name: Oji Ace A, manufactured by Oji Cornstarch) was converted to a solid content by 5% per dry weight of the absolutely dry pigment, and styrene-butadiene latex (trade name: JSR-0692, Japan Synthetic Rubber) 10% by dry weight of absolutely dry pigment in terms of solid content
Was mixed to obtain a coating liquid for a smoothing layer. Then, rice tsubo 84.
9 g / m ² single-sided art paper (trade name: Kanto single-sided, manufactured by Oji Paper Co., Ltd.) was coated with 5 g /
After coating and drying using a blade coater so as to obtain m ² , a super calender treatment was performed to form a smoothing layer. The smoothness of the smoothing layer was 750 seconds. Then, a heat-sealable adhesive layer was provided on the smoothing layer of the art paper in the same manner as in Example 1 to produce a heat-sealable adhesive label.

Example 4 A 10% solution of polyvinyl alcohol (PVA-117, manufactured by Kuraray Co., Ltd.) was used as a coating solution for a smoothing layer.
/ M ² single-sided art paper (trade name: Kanto single-sided, manufactured by Oji Paper Co., Ltd.) was coated on the base paper surface using a bar coater, and the coating solution for the smoothing layer was applied to 3 g / m ² and dried. Super calendering was performed to form a smoothing layer. The smoothness of the smoothing layer was 350 seconds. Then, in the same manner as in Example 1, a heat-sealable adhesive layer was provided on the smoothing layer of the art paper to produce a heat-sealable adhesive label.

Comparative Example 1 A heat-sealable adhesive (trade name: Toyomelt BL-8001) was applied to the base paper of single-sided art paper (trade name: Kanto single side, manufactured by Oji Paper Co., Ltd.) of 84.9 g / m ² in U.S.P. (Toyo Petrolite) was applied using a pan-feed type roll coater to a dry weight of 20 g / m ² to obtain a heat-sealable adhesive label. The smoothness of the base paper side of the single-sided art paper was 135 seconds.

Comparative Example 2 A heat-sealable adhesive label was prepared in the same manner as in Comparative Example 1, except that cast coated paper (trade name: Mirror Cast Gold, manufactured by Oji Paper Co., Ltd.) having a size of 84.9 g / m ² was used. Manufactured. In addition, the smoothness of the base paper surface of the cast coated paper was 24 seconds.

[Evaluation] The obtained heat-sealable adhesive label was placed on a delayed-type pressure-sensitive adhesive labeling device (“Thermolabeler AL type”, manufactured by Takara) at a set hot air temperature of 500 ° C. and a labeling speed of 40 m / min. Labeling was performed on a cylindrical container of a glass bottle and a deformed container of plastic, and the following items were evaluated. The results are shown in Table 1.

[Label sticking property] A cylindrical container of a glass bottle of a heat seal type adhesive label and a plastic (PET)
Was evaluated according to the following criteria. ：: There is no sticking defect and the labeling suitability is good. Δ: Some adhesion failure (unbonded portion) occurred, the appearance was poor, and there was a practical problem. ×: No sticking, many sticking defects, not practical.

[Label Adhesion] The adhered label was peeled off by hand, and from the adhesive strength, whether or not the heat-sealable adhesive label was sufficiently adhered was evaluated according to the following criteria. A: The bonding strength is very strong, and the adhesive is completely stuck. ：: The adhesive strength is very strong, and there is no peeling except for peeling by hand, but the adhesive remains in the container when forcibly peeled off. Δ: The adhesive strength is slightly weak, and the adhesive remains in the container when peeled off by hand. X: The adhesive strength is weak, and the label can be easily peeled off by hand.

[0045]

[Table 1]

As is evident from the results in Table 1, the heat-sealable adhesive label of the present invention does not cause any defective sticking even in glass bottles and plastic deformed containers, and is excellent.

For reference, the six types of heat-sealable adhesive labels used in the above-described Examples and Comparative Examples are as follows.
The following confirmations were made. First, the adhesive layer was dissolved or swelled by immersing the heat-sealable adhesive label in toluene for 3 minutes. Next, the label was lifted from toluene, and the swollen adhesive was scraped off with a rubber spatula, taking care not to damage the surface substrate. Next, the surface base material from which the adhesive layer was scraped off was removed using a hot air drier for 5 minutes.
After drying at 0 ° C., the surface of the base paper was measured for Oken-type smoothness.
The results are shown in Table 2. As is clear from Table 2,
In the present invention, the smoothness of the base paper before the formation of the adhesive layer is specified.

[0048]

[Table 2]

[0049]

As described above, the heat-sealable adhesive label of the present invention is excellent in that no defective sticking occurs even in a glass bottle or a plastic deformed container. In addition, since the labeling device can also be applied to a delayed-type pressure-sensitive adhesive labeling device, the label can be applied to an adherend that is vulnerable to heat.

Claims (3)

[Claims] 1. A heat-sealable adhesive label obtained by applying a heat-sealable adhesive on the back surface of a front substrate,
J Tappi paper pulp test method No. 5. A heat-sealable adhesive label, wherein the smoothness according to No. 5 is 150 seconds or more. 2. A smoothing layer is provided on the back surface of the surface substrate, and the surface of the smoothing layer is subjected to J Tappi paper pulp test method No. 1.
A heat-sealable adhesive label, wherein the heat-sealable adhesive label is obtained by applying a heat-sealable adhesive on the smoothed layer, the smoothness according to No. 5 being 150 seconds or more. 3. The heat-sealable adhesive label according to claim 2, wherein the smoothing layer mainly comprises a synthetic and / or natural polymer having a film-forming property.