JPH09230791A - Method for producing heat-activated label and molded article with label - Google Patents

Abstract

(57) [PROBLEMS] To provide a heat-activated label excellent in low-temperature adhesiveness and free from blocking, and a method for producing the label. In a heat-activatable label including a substrate and an adhesive layer provided on the back surface side of the substrate, the adhesive used in the adhesive layer uses a catalyst system containing a metallocene compound. A heat-activatable label which is a polymerized ethylene-α-olefin copolymer, and a heat-activatable label are preheated, and then the heated heat-activatable label is attached to the surface of a molded product which has been molded in advance. In the method for producing a labeled molded article for producing a labeled molded article, the method for producing a labeled molded article in which the heat-activatable label is the heat-activatable label, and a mold in which a heat-activatable label is preliminarily loaded. A method for producing a labeled molded article, comprising molding a labeled molded article using the method, wherein the heat activated label is the heat activated label.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-activatable label having a high adhesive force, and a method for producing a labeled molding capable of producing a labeled molding with high productivity.

[0002]

2. Description of the Related Art Conventionally, a heat-activatable label having an adhesive layer mainly composed of an ethylene copolymer has been generally used. In such a heat-activatable label, the melting point has been lowered by increasing the amount of the copolymerization component in the ethylene-based copolymer in order to lower the adherable temperature. The copolymerization component used at this time is generally vinyl acetate,
Ethyl acrylate, acrylic acid, methacrylic acid and the like are used (for example, JP-A-2-258556), and in this case, the melting point can be sufficiently lowered and the low temperature adhesiveness can be improved. did it.

However, when the adherend is a molded product made of an olefinic resin, the more the copolymerization component is increased (the lower the melting point is), the poorer the compatibility with the molded product is, and the adhesive force is lowered. There was a problem of being lost. Therefore, in order to improve familiarity with olefin resins, α-olefin is selected as a copolymerization component, and an ethylene-α-olefin polymer polymerized using a conventional general Ziegler-Natta catalyst is used as an adhesive component. Although it has been proposed to use it, ethylene-α-olefins produced by using a Ziegler-Natta catalyst cannot sufficiently lower the melting point and cannot be bonded at low temperatures (for example, 100 ° C. or lower). That is, there is a problem that the low temperature adhesiveness is poor.

In addition, as a method of producing a molded article with a label, in-mold molding is carried out in which molding is carried out in a mold in which a label is loaded in advance. However, in the in-mold molding, since the thickness of the label is further added to the thickness of the molded body, the cooling efficiency of the molded body is poor, and the temperature at which the molded body container is taken out from the mold is high is called a blister. Since the label floats from the molded body, it is necessary to secure a sufficiently long cooling time in the mold. Therefore, the molding cycle in the in-mold molding is generally long, and there is a problem in the productivity of the labeled molded body in the in-mold molding.

Therefore, in order to improve the productivity in in-mold molding, the molding temperature (resin temperature) is set low to lower the heat quantity of the molded body in the mold, and the cooling time is shortened to a relatively high temperature. Generally, a method of taking out the molded body in the above state from the mold is performed. However, in the case of a heat-activated label using a conventional general adhesive as described above, when an adhesive with a low melting point is used to obtain sufficient adhesive strength at a low molding temperature, the cooling time is short, so it is difficult to remove it. When the temperature is high and the adhesive remelts to cause blisters, on the other hand, when an adhesive with a high melting point is used so that blisters do not occur when taking out at a high temperature, there is a problem that the adhesive strength at low molding temperature decreases. .

Therefore, various in-mold molding labels and molding methods have been proposed for the purpose of suppressing the formation of blisters even when molding is performed in a short cycle. For example, Japanese Patent Laid-Open No. 5-2829 proposes a method for producing a labeled hollow container, characterized in that the adhesive layer of the label comprises a mixture of two or more kinds of resins having different melting points satisfying specific conditions. According to this proposal, a resin having a melting point on the high temperature side has a melting point on the low temperature side while suppressing the occurrence of blisters even when the container is taken out from the mold at a high temperature because sticking occurs at a high temperature. Since the resin melts at a low temperature, it plays a role of maintaining the adhesive force at a low molding temperature. However, even if such an adhesive is used, the high-melting-point component still hinders the adhesion of the label to the molded body in low-temperature molding, and the low-melting-point component causes blister generation in high-temperature extraction, so that sufficient productivity is obtained. Improvement was not achieved.

Further, in Japanese Patent Laid-Open No. 5-24048,
A method of manufacturing a labeled container characterized by rapidly cooling a labeled container molded in a short cooling time to a temperature below the crystallization or softening temperature of the adhesive has been proposed. And as a method of this quenching,
It has been proposed to spray water or cooling air, or to cool with a mold prepared for additional cooling. In this proposal, although the occurrence of blisters can be suppressed, it is necessary to introduce a cooling device into a general molding machine, which makes the manufacturing equipment large and complicated, which rather reduces the productivity. Therefore, there is also a problem that the cost is increased.

In addition to these, a proposal for the purpose of improving the adhesive force and preventing the formation of blisters (for example, Japanese Patent Laid-Open No. 4-4
121, JP-A-4-4130, and JP-A-4-4130.
No. 29184, Japanese Patent Laid-Open No. 4-359284, and Japanese Patent Publication No. 6-70736), but these proposals have not achieved sufficient improvement of adhesive strength or sufficient shortening of molding cycle. Is the current situation.

Further, as a method for producing a labeled molded article, a heat-activatable label is heated and activated by using a labeler equipped with a heating device, and the adhesive layer of the heated heat-activatable label is tacky. A so-called labeler bonding method is used in which the heat-activatable label is attached to the surface of a molded body that has been molded in advance while keeping (activity). Then, in such a labeler bonding method, as the adhesive used for the heat-activated label, it is necessary to use one having a low melting point in order to be activated at a temperature as low as possible. When the melting point is lowered by using a copolymerization component such as, ethyl acrylate, (meth) acrylic acid, the melting point range becomes wider and the polarity becomes higher. As a result, blocking already occurs before the label is activated. However, there is a problem in that it is difficult to take out the labels one by one because the stacked labels are stuck to each other. In addition, even after the label is attached to the molded body, the adhesive strength is weak, it takes time for the adhesive to solidify, and when the application speed is fast and cooling is insufficient, the label end surface may float from the adherend. There was also a problem.

In short, the conventional heat-activatable label can obtain a high adhesive force to various molded products including olefin resin molded products at low temperature, and can increase the labeled molded product using a general molding machine. There is a problem that it is impossible to produce at a high production rate, and further, when the heat-activated label is used in a labeler equipped with a heating device, the adhesive strength after blocking or sticking is poor.

Therefore, it is an object of the present invention to provide a heat-activatable label which has excellent low-temperature adhesiveness and does not cause blocking. Further, another object of the present invention is to provide a method for producing a labeled molded article which can significantly reduce the molding cycle even by using an existing in-mold molding machine. Still another object of the present invention is to provide a method for producing a labeled molded article, which does not cause a problem such as label peeling even when adhered by a labeler.

[0012]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that a heat-activatable label in which an adhesive forming an adhesive layer is a specific resin achieves the above object. I found that

The present invention has been made based on the above findings, and is used for the above-mentioned adhesive layer in a heat-activatable label having a base material and an adhesive layer provided on the back surface side of the base material. The heat-activatable label is characterized in that the adhesive is an ethylene-α-olefin copolymer obtained by polymerizing using a catalyst system containing a metallocene compound.

Further, according to the present invention, the melting peak temperature of the ethylene-α-olefin copolymer is 50 to 80 ° C., and the above-mentioned heat used by pasting on a preformed molded article after preheating. An active label is provided.
Further, the present invention provides the above heat-activatable label, wherein the ethylene-α-olefin copolymer has a melting peak temperature of 70 to 100 ° C. and is used by being loaded in a mold for in-mold molding. It is a thing.

Further, according to the present invention, after the heat-activated label is preheated, the heated heat-activated label is attached to the surface of the preformed molded article to produce a labeled molded article. In the manufacturing method of the above, the above-mentioned heat-activatable label is a method for manufacturing a labeled molded article, which is the above-mentioned heat-activatable label of the present invention (hereinafter, when referred to as “first manufacturing method”, The present invention) is provided.

Further, the present invention provides a method for producing a labeled molded article, which comprises molding a labeled molded article using a mold having a heat activated label loaded therein in advance, wherein the heat activated label is the above-mentioned book. The present invention provides a method for producing a labeled molded article, which is the heat-activatable label of the invention (hereinafter, referred to as the “second production method” when referred to as the present invention). The present invention provides a method for molding a labeled molded body, which is a hollow container, wherein the labeled molded body is a molded body molded by a blow molding method, and at least a label adhered surface is made of a polyolefin resin. To do.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The heat-activated label of the present invention will be described in more detail below. The heat-activatable label of the present invention comprises a substrate and an adhesive layer provided on the back side of the substrate,
The adhesive used in the adhesive layer is a specific resin.

In the present invention, the "heat-activatable label" means that various information is preferably printed on the front surface (back surface) of the substrate, and the adhesiveness and adhesiveness can be obtained by heating the substrate at a temperature higher than room temperature. Is a label that is expressed (heat-activated), does not exhibit tackiness and adhesiveness before heat activation, that is, at room temperature, and can be stored and handled without using release paper or the like. Further, as a method for adhering the heat-activatable label, a labeler adhering method for sticking a label activated by heating to an already manufactured molding, and a thermo-activatable label inside when molding a resin molding. Molding is carried out using a mold loaded with, and the heat-activated label is activated by the heat of the resin to attach the label to the molded body.

The above-mentioned substrate used in the present invention includes paper, synthetic paper (for example, a film obtained by stretching a resin and an inorganic filler), unstretched or stretched plastic film (for example, polyethylene resin, polypropylene resin). , Polyester-based resins, polystyrene-based resins, polyamide-based resins, etc.), nonwoven fabrics, and the like. Further, in particular, when the heat-activated label of the present invention is used in an in-mold molding method (particularly when a thin molded body is molded by the in-mold molding method), deformation of the molded body is prevented. Therefore, a base material made of a material having a mechanical property (for example, a relatively small elastic modulus) that shrinks at a shrinkage rate close to the heat shrinkage rate of the molded body or can follow the shrinkage of the molded body is preferable. An unstretched plastic film of polypropylene resin or polyethylene resin is preferably used. Further, the base material may be divided into a plurality of layers in the label constitution, or may be a laminate of different materials.

When the base material is located on the outermost side of the product, it is preferable to subject the base material to an antistatic treatment. As a method of antistatic treatment, a method of coating a known antistatic agent on the surface of a substrate, a method of adding an antistatic agent to a material for forming a substrate, and the like are used. When the antistatic agent is added to the material for forming the base material, the addition amount of the antistatic agent is arbitrary, but the base material is formed by adding it in a concentration distribution that does not impair the adhesiveness with other layers. Preferably. Further, it is preferable to perform a surface treatment such as corona treatment on the surface of the base material on which printing is performed to improve printability. In addition, the heat applied to the adhesive layer during thermal activation of the label is conducted to the device (the mold for in-mold molding or the labeler drum for the post-adhesion method) that comes into contact with the label and the activation efficiency deteriorates. In order to prevent this, a heat insulating material such as foamed plastic can be used as the base material (a part of the base material).

The thickness of the substrate is preferably 40 to 200 μm, particularly preferably 60 to 150 μm. If the thickness is less than the lower limit, the label becomes stiff and it becomes difficult to attach it to the molded body or load it inside the mold, and if it is thicker than the upper limit,
In particular, when used for in-mold molding, it tends to cause blisters, which is not preferable.

As the method of printing on the above-mentioned substrate, general methods such as gravure printing, offset printing, flexographic printing and screen printing can be used without particular limitation.

In the heat-activated label of the present invention,
The specific resin used as the adhesive is an ethylene-α-olefin copolymer (hereinafter abbreviated as “MPE”) polymerized by using a catalyst system that uses a metallocene compound.

As the α-olefin used in the above MPE, for example, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-heptene, 4-
Α-C3 to C20 such as methylpentene-1,4-methylhexene-1,4-dimethylpentene-1, octadecene, isooctene, isooctadiene and decadien
Examples of the olefin include 1-hexene and 1-hexene.
Octene, 1-heptene and 4-methylpentene-1 are preferred. Further, these α-olefins can be copolymerized with ethylene in one kind or in two or more kinds.

Further, the copolymerization ratio of the above α-olefin is preferably 5 to 30 wt% in the whole copolymer. That is, it is preferable to copolymerize the blending amount of the α-olefin with 5 to 30 wt% with respect to the total amount of ethylene and the α-olefin. In particular, the copolymerization ratio is 10 to 25 wt% when the heat-activatable label is a label used in the labeler bonding method, and 5 to 20 wt% when the heat-activated label is a label used in an in-mold molding method.
It is preferred that If the copolymerization ratio is less than the above lower limit, the adhesive strength is likely to be insufficient, so activation or molding at a high temperature is required, while if it exceeds the upper limit, blocking or blister generation is likely to occur. Not preferable.

Examples of the catalyst system containing the above metallocene compound used in the present invention include a catalyst system consisting of a metallocene compound alone, or a catalyst system containing a metallocene compound as a main catalyst and further containing a cocatalyst.

Examples of the metallocene compound include metallocene compounds represented by the following formula (I). ML _X (I) wherein M is a transition metal selected from the group consisting of Zr, Ti, Hf, V, Nb, Ta and Cr, and L is
A ligand having a cyclopentadienyl skeleton, which is a ligand coordinated to the transition metal, a hydrocarbon group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, and an aryl group having 1 to 12 carbon atoms.
Roxy group, C1-C12 trialkylsilyl group, S
O ₃ R group (where R is a hydrocarbon group having 1 to 8 carbon atoms which may have a substituent such as halogen), a halogen atom or a hydrogen atom, and x is the same as the valence of the above transition metal. Is. However, when a plurality of Ls are coordinated, they may be different groups, but at least one is a group having a cyclopentadienyl skeleton. That is,
When x is 1, L is a group having a cyclopentadienyl skeleton, and when x is 2 or more, at least one of a plurality of L is a cyclopentadienyl skeleton. Is a group having ]

Examples of the group having a cyclopentadienyl skeleton include cyclopentadienyl group, methylcyclopentadienyl group, dimethylcyclopentadienyl group, trimethylcyclopentadienyl group, tetramethylcyclopentadienyl group. Enyl group, pentamethylcyclopentadienyl group, ethylcyclopentadienyl group, methylethylcyclopentadienyl group, propylcyclopentadienyl group, methylpropylcyclopentadienyl group,
Alkyl-substituted cyclopentadienyl groups such as butylcyclopentadienyl group, methylbutylcyclopentadienyl group, hexylcyclopentadienyl group; or indenyl group, 4,5,6,7-tetrahydroindenyl group, fluorenyl A group etc. can be illustrated. Further, these groups may be substituted with a halogen atom, a trialkylsilyl group or the like.

As the group having a cyclopentadienyl skeleton, an alkyl-substituted cyclopentadienyl group is particularly preferable among the above-exemplified groups.

When the metallocene compound represented by the general formula (I) contains two or more groups having a cyclopentadienyl skeleton, the two groups having a cyclopentadienyl skeleton among them are , An alkylene group such as ethylene and propylene; a substituted alkylene group such as isopropylidene and diphenylmethylene; a silylene group or a substituted silylene group such as a dimethylsilylene group, a diphenylsilylene group, and a methylphenylsilylene group may be bonded. .

Examples of the hydrocarbon group having 1 to 12 carbon atoms include an alkyl group, a cycloalkyl group, an aryl group and an aralkyl group. More specifically, the alkyl group is a methyl group, Ethyl group, propyl group,
Examples include isopropyl group and butyl group, examples of cycloalkyl group include cyclopentyl group and cyclohexyl group, examples of aryl group include phenyl group and tolyl group, and examples of aralkyl group include benzyl group and neophyll group. Examples include groups. Examples of the alkoxy group include methoxy group, ethoxy group, butoxy group, etc., examples of the aryloxy group include phenoxy group, etc., and examples of the halogen atom include fluorine, chlorine, bromine, iodine and the like.

Examples of the SO ₃ R group include p-toluenesulfonato group, methanesulfonato group, trifluoromethanesulfonato group and the like.

As the metallocene compound containing a group having such a cyclopentadienyl skeleton, for example, when the valence of the transition metal is 4, more specifically, the following formula (I
Indicated by I).

R ² _k R ³ _l R ⁴ _m R ⁵ _n M (II) [wherein, M is the above transition metal, and R ² is a group having a cyclopentadienyl skeleton (ligand ), And R ³ , R
⁴ and R ⁵ are each a group having a cyclopentadienyl skeleton, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a trialkylsilyl group, a SO ₃ R group, a halogen atom or a hydrogen atom. Where k is an integer greater than or equal to 1, and k + 1 + m
+ N = 4. ]

In the present invention, in the above formula (II), R
^A metallocene compound in which at least two of ² , R ³ , R ⁴ and R ⁵ , for example, R ² and R ³ are groups (ligands) having a cyclopentadienyl skeleton is preferably used. Groups having an enyl skeleton (eg R ² and R ³ ) may be attached as described above.

Specific examples of the metallocene compound in which M is zirconium are shown below. Bis (indenyl) zirconium dichloride, bis (indenyl) zirconium dibromide, bis (indenyl) zirconium bis (p-toluenesulfonato) bis4,
5,6,7-Tetrahydroindenyl) zirconium dichloride, bis (fluorenyl) zirconium dichloride, ethylenebis (indenyl) zirconium dichloride, ethylenebis (indenyl) zirconium dibromide, ethylenebis (indenyl) dimethylzirconium, ethylenebis (indenyl) Diphenylzirconium, ethylenebis (indenyl) methylzirconium monochloride, ethylenebis (indenyl) zirconium bis (methanesulphonate), ethylenebis (indenyl) zirconium bis (p-toluenesulphonate), ethylenebis (indenyl) zirconium bis (trifluor) Rmethanesulfonato), ethylene bis (4,5,6)
7-Tetrahydroindenyl) zirconium dichloride, isopropylidene (cyclopentadienyl-fluorenyl) zirconium dichloride, isopropylidene (cyclopentadienyl-methylcyclopentadienyl) zirconium dichloride, dimethylsilylenebis (cyclopentadienyl) zirconium dichloride , Dimethylsilylenebis (methylcyclopentadienyl) zirconium dichloride, dimethylsilylenebis (dimethylcyclopentadienyl) zirconium dichloride, dimethylsilylenebis (trimethylcyclopentadienyl) zirconium dichloride, dimethylsilylenebis (indenyl) zirconium dichloride, dimethyl Silylenebis (indenyl) zirconium bis (trifluoromethanesulfonato), dimethyl Shirirenbisu (4,
5,6,7-Tetrahydroindenyl) zirconium dichloride, dimethylsilylenebis (cyclopentadienyl-fluorenyl) zirconium dichloride, diphenylsilylenebis (indenyl) zirconium dichloride, methylphenylsilylenebis (indenyl) zirconium dichloride, bis (cyclopenta) Dienyl) zirconium dichloride, bis (cyclopentadienyl) zirconium dibromide, bis (cyclopentadienyl)
Methylzirconium monochloride, bis (cyclopentadienyl) ethylzirconium monochloride, bis (cyclopentadienyl) cyclohexylzirconium monochloride, bis (cyclopentadienyl) phenylzirconium monochloride, bis (cyclopentadienyl)
Benzyl zirconium monochloride, bis (cyclopentadienyl) zirconium monochloride, bis (cyclopentadienyl) methylzirconium monohydride, bis (cyclopentadienyl) dimethylzirconium, bis (cyclopentadienyl) diphenylzirconium, Bis (cyclopentadienyl) dibenzylzirconium, bis (cyclopentadienyl)
Zirconium methoxy chloride, bis (cyclopentadienyl) zirconium ethoxy chloride, bis (cyclopentadienyl) zirconium bis (methanesulfonato), bis (cyclopentadienyl) zirconium bis (p-toluenesulfonato), bis (cyclo Pentadienyl) zirconium bis (trifluoromethanesulfonato), bis (methylcyclopentadienyl) zirconium dichloride, bis (dimethylcyclopentadienyl)
Zirconium dichloride, bis (dimethylcyclopentadienyl) zirconium ethoxy chloride, bis (dimethylcyclopentadienyl) zirconium bis (trifluoromethanesulfonate), bis (ethylcyclopentadienyl) zirconium dichloride, bis (methylethylcyclopentadiene) (Enyl) zirconium dichloride, bis (propylcyclopentadienyl) zirconium dichloride, bis (methylpropylcyclopentadienyl)
Zirconium dichloride, bis (butylcyclopentadienyl) zirconium dichloride, bis (methylbutylcyclopentadienyl) zirconium dichloride, bis (methylbutylcyclopentadienyl) zirconium bis (methanesulfonato), bis (trimethylcyclopentadienyl) ) Zirconium dichloride, bis (tetramethylcyclopentadienyl) zirconium dichloride,
Bis (pentamethylcyclopentadienyl) zirconium dichloride, bis (hexylcyclopentadienyl)
Zirconium dichloride, bis (trimethylsilylcyclopentadienyl) zirconium dichloride.

In the above-exemplified compounds, disubstituted cyclopentadienyl rings such as dimethylcyclopentadienyl include 1,2- and 1,3-substituted compounds,
Trisubstituted compounds such as dimethylcyclopentadienyl are 1,2,2
Includes 3- and 1,2,4-substitutes. Also propyl,
Alkyl groups such as butyl are n-, i-, sec-, te
Including isomers such as rt-. Further, examples of the metallocene compound include metallocene compounds obtained by substituting zirconium with titanium, hafnium, vanadium, niobium, tantalum, or chromium in the above compound in which M is zirconium. When using the above metallocene compounds, they can be used alone or as a mixture. It may be used after being diluted with a hydrocarbon or a halogenated hydrocarbon. In the present invention, as the metallocene compound, a zirconocene compound (metallocene compound) having a central metal atom of zirconium and a group having at least two cyclopentadienyl skeletons as a ligand is preferably used.

The cocatalyst that can be used in combination with the metallocene compound includes a usual aluminoxane compound or a compound that reacts with the metatheron compound to form a stable anion.

The above ethylene / α-olefin copolymer can be easily produced by a known method using the above catalyst system. Specifically, ethylene and α-olefin are added to the above catalyst system. In the presence, in a wide temperature and pressure range, solution polymerization, liquid phase polymerization method such as slurry polymerization,
Alternatively, it can be produced by polymerizing by a gas phase polymerization method. In particular, in order to polymerize the above metallocene compound and the above aluminoxane compound in combination, the method described in JP-A-61-
No. 130314, No. 60-35006, No. 6
No. 0-35007, No. 58-19309, No. 60-35008, JP-A No. 3-1630888, and the like, and a stable anion that reacts with the metallocene compound and the metallocene compound. In order to polymerize the compound forming the compound in combination, European Patent No. 277,004, International Publication WO92 / 01
Polymerization can be carried out according to the high-pressure ionic polymerization method described in Japanese Patent No. 723, etc.

The melting point of the MPE is DSC (heating rate 1
50 ° C at the melting peak temperature measured at 0 ° C / min)
It is preferably in the range of -100 ° C. That is, the melting peak temperature of the ethylene-α-olefin copolymer is
It is preferably 50 to 100 ° C. Particularly, when the heat-activatable label of the present invention is a label used for the labeler adhesion method, it is 50 ° C. to 80 ° C., and when it is a label used for the in-mold molding method, it is 70 ° C. to 100 ° C. , Respectively preferred. That is, the heat-activated label of the present invention has a melting peak temperature of the above MPE of 50 to 80 ° C., is preheated, and is then heat-activated for the labeler bonding method, which is used by being attached to a preformed molded article. It is a mold label or the melting peak temperature of the MPE is 70-100.
The heat-activatable label for in-mold molding, which is at a temperature of 0 ° C. and is used by being loaded in a mold for in-mold molding, is preferable. The number of melting peaks is arbitrary depending on the purpose, and may be one or plural.

The MPE has a density of 0.86 to
It is preferably 0.93 g / cm ² , and particularly when the heat-activatable label of the present invention is a label used in the labeler adhesion method, 0.86 to 0.90 g / cm ² in-mold molding method If the label is used for 0.
It is preferably 88 to 0.92 g / cm ² .

If the melting point or the density is less than the above lower limit, blocking during storage of the label or peeling of the label in the summer is likely to occur, and the heat-activated label of the present invention is used in the labeler bonding method. In the case of a label, the hot tack property is insufficient, and in the case of a label used in an in-mold molding method, it is likely to cause blister generation, which is not preferable. Further, if the respective upper limits are exceeded, the adhesive strength tends to be insufficient, which is not preferable.

The MPE melt index (JIS K-7210; measured at 190 ° C., 2.16 kg load) is preferably 0.1 to 50 g / 10 min, particularly preferably 0.3 to 30 g / 10 min. Is. When the melt index is out of the preferred range,
Processing such as extrusion molding for forming the adhesive layer is difficult, and at the same time, defective adhesion is likely to occur, which is not preferable.

In the present invention, the MPE is preferably formed into a film and used. Therefore, the above MPE
Requires good processability in various film molding (single-layer and multi-layer film molding such as T-die molding and inflation molding), and therefore the MPE has the following properties. Is preferred.

It has long-chain branching compared to the branching formed by α-olefins. As described above, the long-chain branching improves the melt property of the resin and improves the processability. Further, the ethylene-α-olefin copolymer having such a long-chain branch is, for example, PC
T application 093/08221 (Table 7-500622)
It can be produced by the general method described in Japanese Patent Laid-Open Publication No. 2003-331, and specifically, it can be easily produced as follows. That is, an olefin polymer having long chain branching is formed by copolymerizing a vinyl compound having a relatively long hydrocarbon chain and an olefin monomer using a metallocene catalyst to form a desired branched polymer. To manufacture.

It has two or more peaks in the molecular weight distribution, or has a relatively broad molecular weight distribution. In such a case, since the low molecular weight component is contained, the processability is improved. The ethylene-α-olefin copolymer having two or more peaks in such a molecular weight distribution and the ethylene-α-olefin copolymer having a relatively wide molecular weight distribution are disclosed in JP-A-60-35008, respectively. It can be produced by the ordinary method described in JP-A-7-500859 or the like, but specifically, "multistep polymerization method",
A “polymerization method using a mixed catalyst”, a method of melt-blending two or more kinds of resins having different peaks of different molecular weight distribution, and the like are used.

The difference in melt viscosity can be used as an index showing the improved melt property. In this case, the MPE is the logarithm with the viscosity η (10) poise at the shear rate of 10 sec ^-1 as the base, and the viscosity η (100) poise of 10 at the shear rate of 100 sec ^-1 as the base. With the logarithm Δ logη = logη (10) −logη
The value of (100) is preferably 0.2 or more,
More preferably 0.25 or more, still more preferably 0.3.
That is all. By satisfying the above range, better moldability can be obtained.

MPE has a sharper molecular weight distribution than the conventionally used low melting point resins, and the distribution of the presence of the copolymerization component in the molecular chain is uniform, so that the melting point is linear with the increase of the copolymerization component. It is characterized in that it has a significantly reduced amount of low molecular weight components that cause stickiness and blocking and has high transparency.

When used as an adhesive for labels,
It has the following excellent advantages: -The melting and crystallization behavior is sharp, and heat activation and adhesion can be completed in a short time. In particular, since the drag of the melting peak to the low temperature side is small, when used in the in-mold molding method, heat back (after taking out from the mold,
Suppress the occurrence of blisters due to remelting of the adhesive due to heat conduction inside the molded body and a rise in the surface temperature. Also, in the case of labeler adhesion, there are advantages such as quick solidification. -By adjusting the copolymerization ratio of α-olefin, the melting point can be adjusted according to the molding temperature, and the heat activation temperature can be freely set by the bonding method.・ Because the copolymerization component is α-olefin, it has high adhesion to olefin resin moldings, and is sufficiently practical even at low adhesion temperatures compared to conventional adhesives with similarly low activation temperatures. Can be secured. In the conventional adhesive polymer, when the amount of the copolymerization component was increased in order to lower the melting point, stickiness and blocking occurred due to the increase of the low molecular weight component.
Since PE has a very small amount of low molecular weight components, it is difficult to block and is not sticky. Therefore, the heat-activatable label of the present invention is excellent in processability such as printing, slitting, punching and the like, and is also excellent in handleability at the time of label attachment such as loading into a mold. In the case of a heat-activatable label that is required to have a transparent portion, the adhesive layer does not fog, so that a label with extremely high transparency can be obtained.

As the MPE, AFFINI
TY "PL1845", "PF114", "SM125"
0 "," HM1100 ";ENGAGE" KC885 "
2 ”,“ EG8200 ”[all above, trade names, manufactured by Dow Chemical Co., Ltd.], EVOLUE“ SP1540 ”[trade name, manufactured by Mitsui Petrochemical Industry Co., Ltd.], EXACT [trade name, manufactured by Exxon], etc. Goods can also be used.

In the heat-activatable label of the present invention, the above-mentioned MPE may be used alone as the above-mentioned adhesive used in the above-mentioned adhesive layer, but it may also be used as a mixture with other substances if necessary. it can. Examples of the other substances mentioned above include general polyethylene resins (low density polyethylene, linear low density polyethylene, high density polyethylene,
Or copolymers of ethylene with 4-methylpentene-1, vinyl acetate, ethyl acrylate, acrylic acid, methacrylic acid, etc.), polypropylene, polystyrene resins, polyester resins, polyamide resins, petroleum resins, etc. Can be mentioned. When the above-mentioned other substance is used, the amount of the other substance used is preferably 50 with respect to the whole adhesive.
wt% or less, more preferably 30 wt% or less, MP
It is preferred that the range of E is not impaired.

The adhesive layer may be formed by only the adhesive, but in addition to the adhesive, a plasticizer such as liquid paraffin, a wax such as paraffin wax and polyethylene wax, a fatty acid amide and a fatty acid. A slip agent such as a metal salt, an anti-blocking agent such as an inorganic or organic filler, and the like can be added to the extent that the desired effects of the present invention are not impaired.

The thickness of the adhesive layer is 0.5-5.
0 μm is preferable, and 1 to 20 μm is particularly preferable.

The heat-activatable label of the present invention has a multi-layered structure comprising the above-mentioned base material and the above-mentioned adhesive layer, and is usually further subjected to printing as described above to provide a printing layer. In addition, a publicly known metal vapor deposition (or metal foil) layer, a publicly known adhesive layer for adhering each layer, a publicly known anchor coat layer, and the like are appropriately provided as necessary. Further, the base material may be provided not only in one layer but in two or more layers. Specific examples of the constitution of the heat-activatable label of the present invention include, from the front side of the label, base material / printing layer / metal vapor deposition layer / adhesive layer, metal vapor deposition layer / printing layer / base material / adhesive layer, first A base material / printing layer / metal vapor deposition layer / second base material / adhesive layer is generally used (an adhesive layer or an anchor coat layer is provided between the layers as necessary). Further, the thickness of the heat-activated label of the present invention is preferably 30 to 300 μm. If the thickness is less than the above lower limit, the label becomes stiff and it becomes difficult to attach it to a molded article or load it inside the mold, and if it exceeds the above upper limit, the blister of the blister is particularly used in the in-mold molding method. This is not preferable because it easily causes the problem.

The heat-activatable label of the present invention can be easily manufactured as follows. That is, a co-extrusion method in which a base material and an adhesive are extruded in multiple layers, an extrusion laminating method in which an adhesive is melt-extruded to a base material subjected to a necessary treatment, a T-die molding or an inflation molding in advance. The base material and the adhesive layer are laminated by a dry lamination method or the like in which the formed adhesive film is attached to the base material using another adhesive, and then another layer (metal vapor deposition layer or printed layer)
Can be easily obtained by a known method, or by forming the above-mentioned other layer on the above-mentioned base material in advance before laminating. When the dry laminating method is adopted, the base material (first base material) to be bonded
A method of dry laminating a laminated film obtained by co-extruding a resin layer (second base material) having mechanical properties close to that of the above with an adhesive and further laminating it with the base material (first base material). It is preferable to use it in order to obtain a curl-free label.

In forming the adhesive layer, a concave-convex pattern is formed so that air is not entrapped between the adhesive layer and the molded body that is the adherend when the label is adhered. It is preferable. In particular, it is effective to form a concavo-convex pattern on the heat-activated label used in the in-mold molding method. When the concavo-convex pattern is formed, the concavo-convex pattern has a slit shape, an irregular shape or the like, and the size of the convex portion (concave portion) is also irregular. Further, the height of the convex portion in the concavo-convex pattern is preferably 0.3 to 20 μm, and the ratio of the convex portion to the total area is 30 to 9 μm.
It is preferably 0%. As a method of forming the uneven pattern, a method of extruding a film on a roll having an uneven pattern, a method of embossing the molded adhesive film with an embossing roll, another heat-adhesive resin soluble in a solvent (for example, Examples include a method of forming a dot pattern or the like made of ethylene-vinyl acetate copolymer) on the adhesive layer by gravure printing, a method of adding a filler having a relatively large particle size to the adhesive layer, and the like. To be

Next, the method for producing the labeled molded article of the present invention will be described in detail. The first manufacturing method of the present invention is a method for manufacturing a labeled molded article by preheating a heat-activatable label and then applying the heated heat-activatable label to the surface of a molded article that has been previously molded, That is, the labeler bonding method. The heat-activated label is the heat-activated label of the present invention.

Here, as the material for forming the molded body,
Polyolefin resin such as ethylene resin and propylene resin, polystyrene resin, polyester resin,
Polyamide-based resins, poly (meth) acrylic-based resins and the like are mentioned, and among them, polyolefin-based resins are preferably used. Examples of the molded body include moldable materials such as bottles, caps, sheets, films, tubes, and pipes made of the above-mentioned forming materials. Specifically, the above-mentioned first manufacturing method comprises heating the heat-activatable label with a heater or the like to heat-activate the heat-activatable label, and then molding the heat-activatable label while the adhesive layer is activated. The heat-activatable label 1 is fixed to the heated support 12 so that the adhesive layer is on the outer side, and the label 1 activated by the heat of the support 12 is attached to the label 12, as shown in FIG. The method of bringing the label 1 together with the support 12 into contact with the bottle 11 as a molded body, transferring the label 1 to the bottle 11 and adhering the label 1 and the like can be mentioned. Here, as the support 12, a roll or the like can be preferably used. In addition, it is preferable that the temperature at which the heat-activatable label is adhered is set to a high temperature within a range in which the molded body does not undergo thermal deformation in order to obtain high adhesive force and shorten the adhering time.

The second manufacturing method of the present invention is a manufacturing method for molding a labeled molded article by using a mold in which a heat-activatable label is loaded in advance, that is, an in-mold molding method. The heat-activated label is the heat-activated label of the present invention.

Further, it is preferable that the above-mentioned molded product is a molded product molded by a blow molding method, and that it is a hollow container in which at least the label adhered surface is made of a polyolefin resin. Specifically, as the hollow container as the molded body, for example, the outermost layer is made of an ethylene-based resin, and a multilayer resin laminate having a gas barrier layer made of an ethylene-vinyl alcohol copolymer on the inner surface side thereof. Examples include bottles made from the body.

As the above-mentioned mold, any one can be used without particular limitation as long as it is usually used for producing a molded body. Further, the in-mold molding method may be any method as long as it is a method of previously loading a label in a mold and molding a molded body therein, for example, extrusion blow molding or injection blow molding. Blow molding method, compression molding, pressure molding, vacuum molding, injection molding.

As a means for loading the above-mentioned heat-activatable label into a mold, a general method of fixing by vacuum or static electricity can be used.

The resin temperature of the molded body during the in-mold molding is, for example, 160 in extrusion blow molding when the material forming the molded body is polyethylene.
C to 240 C, 180 to 260 C in injection molding,
It is 160 to 240 ° C. in the pressure forming and the vacuum forming, but it is preferable to select a lower temperature in the above range in order to shorten the forming cycle. The pressure is 1.5 to 15 kgf / cm ^{2 for} extrusion blow molding and pressure molding, 20 to 200 kgf / cm ² for injection molding, and ² to 600 mm for vacuum molding.
Although it is HG, it is preferable to increase the pressure with which the resin is pressed against the mold in consideration of the cooling efficiency of the molded body.

The extrusion blow molding method as one mode of the second manufacturing method will be described in detail with reference to the drawings. First, as shown in FIG. 2 (a), resin is first pushed out from the die 21. , Create the parison 22. At this time, the heat-activatable label 1 is attached in the mold 23. Next, as shown in FIG. 2B, the mold 23 is closed, air is blown into the parison 22 at the above pressure, and the parison 22 is blown to mold the container 24. Glue to the outer surface of.

[0065]

The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited thereto. The adhesive resins used in Examples and Comparative Examples are shown in [Table 1]. [Table 1] also describes Δ log η, which is an index of moldability, for the ethylene-α-olefin copolymers used in the examples.

[0066]

[Table 1]

Example 1 (Example of Labeler Adhesion Method) A heat-activatable label was manufactured as follows. Homopolypropylene (PP) [Mitsui Petrochemical Co., Ltd., trade name "B200"] and the adhesive shown in [Table 2] are co-extruded with a T-die to form a two-layer laminated film, A label laminate having a base material and an adhesive layer respectively was obtained. Further, at the time of cooling, a cooling roll having irregularities was used on the adhesive layer side to form a fine irregular pattern (height of convex portions 3 μm, ratio of total area of convex portions 70%) on the adhesive layer. . The thickness of the base material was 100 μm, and the thickness of the adhesive layer was 10 μm. Then, after printing on the surface of the base material of this label laminate, it is punched into a size of 120 mm in length and 60 mm in width,
A heat activated label of the present invention was obtained.

Next, as a molded body as an adherend, a hollow container made of a high density polyethylene (HDPE) molded by a general extrusion blow molding machine (height: about 200 mm, container cross section is substantially elliptical, The major axis is about 90 mm and the minor axis is 75
mm) was prepared. Then, the heat-activated label is fixed to a roll heated to 80 ° C. so that the adhesive layer is on the outer side, and the label activated by the heat of the support is transferred from the support to the molded product, and the molded product A heat-activatable label was adhered to. The same operation was performed at a roll temperature of 100 ° C. If the adhesion temperature exceeds 110 ° C, the container may be thermally deformed, so 100 ° C was set as the limit.

The adhesive strength of the obtained labeled molded article was measured as follows. The results are shown in [Table 2]. Adhesive strength: When the label-bonded portion of the labeled molded article is cut into a 15 mm strip, and a tensile test is performed with a Tensilon tensile tester at a speed of 300 mm / min in an environment of 23 ° C., when the label is peeled from the container. Was measured and used as the adhesive strength. The practical adhesive strength varies depending on the purpose, but it is 300 gf / 15 mm or more when there is no need to peel it off at a later time, and 100 gf / 15 mm or more when it is necessary to peel easily.

[Examples 2 to 4 and Comparative Examples 1 to 4] Production of a heat-activatable label was carried out in the same manner as in Example 1 except that the adhesive resins used were the resins shown in [Table 2]. A labeled molded article was manufactured and an adhesive strength test was performed. The results are shown in [Table 2].

[0071]

[Table 2]

As is clear from the results shown in [Table 2],
It can be seen that the heat-activatable label of the present invention is firmly adhered to the molded body under any condition and has higher adhesiveness than the comparative example. In the case of the comparative example, 8
At the bonding temperature of 0 ° C., the bonding was insufficient in all cases, and a large float was observed at the edge of the label, and the bonding strength was also very small.
Among them, EMAA obtained by copolymerizing methacrylic acid, which has the highest polarity, with ethylene had large floating at any bonding temperature, and was not in a state of bonding.

Example 5 (Example of In-Mold Molding Method) A heat-activatable label was manufactured as follows. A 50 μm homo PP film [TOSERO CORPORATION, trade name “SI-60”] is printed on one side by a gravure printing method to form a printing layer, and a laminate (hereinafter, referred to as a laminate A, (This stack is called)
I got Separately from this, homo-PP [trade name "B200" manufactured by Mitsui Petrochemical Co., Ltd.] and the adhesive shown in [Table 3] are co-extruded with a T-die to form a base material made of PP. A two-layer laminated film having a thickness of 50 μm and an adhesive layer of 10 μm (hereinafter, referred to as a laminated body B means this laminated body) was obtained. Further, at the time of cooling, a cooling roll having irregularities is used on the adhesive layer side, and the adhesive layer is provided with a fine irregular pattern (height of convex portions is 3 μm, proportion of the total area of convex portions is 70%).

Then, the laminate A and the laminate B, the adhesive layer of the laminate A and the base material of the laminate B are dry-laminated by a urethane-based adhesive for dry lamination. To obtain one laminated film. Furthermore, this laminated film is 120 mm long and 60 m wide.
The heat-activated label of the present invention was obtained by punching to a size of m.

Next, using the obtained heat-activated label,
A hollow container as a labeled molded product was molded by extrusion blow molding as follows. That is, a high-density polyethylene [Showa Denko KK, trade name "5
503D ”] to extrude a molten resin parison at 180 ° C., and then blow compressed air of 5 kgf / cm ² into the parison in a mold loaded with a label inside to form a labeled hollow container. did. The cooling time of the molded body in the mold was 10 seconds.

Further, the same operation was performed except that the cooling time was set to 8 seconds and 6 seconds, and a labeled molded article was further manufactured.

The obtained labeled molded article was evaluated for adhesive strength and blister as follows.
The results are shown in [Table 3]. Adhesive strength: The same as in Example 1. Evaluation of blister: Approximately 24 hours after molding, the blister was visually observed and evaluated according to the following criteria. ◯: Labels are not lifted at all Δ: Labels are lifted to the extent that they cannot be recognized at first glance. X: There is a floating label that can be recognized at a glance.

[Examples 6 to 9 and Comparative Examples 5 to 8] Production of heat-activatable labels was carried out in the same manner as in Example 5 except that the adhesive resins used were the resins shown in [Table 3]. A labeled molded article was manufactured and an adhesive strength test was performed. The results are shown in [Table 3].

[0079]

[Table 3] Examples 5 and 6 are the results of using metallocene LLDPE having a high melting point of about 100 ° C. as an adhesive. The adhesive strength is higher than that of Comparative Examples 5 and 6 using EVA having a melting point lower than that, and has practical strength. Although blister was also generated by cooling for 6 seconds, it did not occur until 8 seconds, which was sufficient for practical use. Did not. In Examples 7 and 8, metallocene LLDPE having a lower melting point than Examples 5 and 6 was used as the adhesive.
In the measurement of the adhesive strength, interfacial peeling between the adhesive and the base material or the base material is broken, and the adhesive strength between the adhesive and the container is 4000.
It was an extremely high value exceeding gf / 15 mm. Blister also did not occur at all cooling times. Comparative Example 5
The results of using EVA having different melting points for the adhesives are as follows. The adhesive strength is smaller than that of metallocene LLDPE having a similar melting point, and the blister also shows the case of performing sufficient cooling of Comparative Example 7. Occurred except. In Comparative Example 8, EMAA, which has the highest polarity in Examples, was used as the adhesive, but the adhesive strength was extremely low, and at the same time, the label was largely lifted at any cooling time.

[0080]

The heat-activatable label of the present invention has excellent low-temperature adhesiveness and does not cause blocking. Also,
According to the method for producing a labeled molded article of the present invention, it is possible to significantly reduce the molding cycle even by using an existing in-mold molding machine, and there is a problem such as peeling of the label even when adhered by a labeler. Absent.

[Brief description of drawings]

FIG. 1 is a schematic view showing one embodiment of a method for producing a labeled molded article (first production method) of the present invention.

FIG. 2 is a schematic view showing one embodiment of a method for producing a labeled molded article (first production method) of the present invention, (a) showing a state before blowing. And (b)
[Fig. 6] is a diagram showing a state after blowing.

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[Procedure amendment]

[Submission date] November 5, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction contents]

Therefore, various in-mold molding labels and molding methods have been proposed for the purpose of suppressing the formation of blisters even when molding is performed in a short cycle. For example, Japanese Patent Laid- Open No. 5-8289 proposes a method for producing a labeled hollow container, characterized in that the adhesive layer of the label is composed of a mixture of two or more kinds of resins having different melting points satisfying specific conditions. According to this proposal, a resin having a melting point on the high temperature side has a melting point on the low temperature side while suppressing the occurrence of blisters even when the container is taken out from the mold at a high temperature because sticking occurs at a high temperature. Since the resin melts at a low temperature, it plays a role of maintaining the adhesive force at a low molding temperature. However, even if such an adhesive is used, the high-melting-point component still hinders the adhesion of the label to the molded body in low-temperature molding, and the low-melting-point component causes blister generation in high-temperature extraction, so that sufficient productivity is obtained. Improvement was not achieved.

Claims (6)

[Claims] 1. A heat-activatable label comprising a substrate and an adhesive layer provided on the back side of the substrate, wherein the adhesive used in the adhesive layer is a catalyst system containing a metallocene compound. A heat-activatable label, which is an ethylene-α-olefin copolymer obtained by polymerization. 2. The melting peak temperature of the ethylene-α-olefin copolymer is 50 to 80 ° C., and the ethylene-α-olefin copolymer is used by pasting it on a preformed molded article after preheating. Item 2. A heat-activated label according to item 1. 3. The melting peak temperature of the ethylene-α-olefin copolymer is 70 to 100 ° C., and the ethylene-α-olefin copolymer is used by being loaded in a mold for in-mold molding. Heat activated label. 4. A method for producing a labeled molded article, which comprises preheating a thermally activated label and then applying the heated thermally activated label to the surface of a previously molded article to produce a labeled molded article. The method for producing a labeled molded article, wherein the heat-activated label is the heat-activated label according to claim 1 or 2. 5. A method for producing a labeled molded article, which comprises molding a labeled molded article using a mold in which a heat activated label is preliminarily loaded, wherein the thermally activated label is according to claim 1 or 3. A method for producing a labeled molded article, which is a heat-activated label. 6. The labeled molded article is a molded article molded by a blow molding method, and is a hollow container in which at least a label adhered surface is made of a polyolefin resin. A method for molding the labeled molded article described.