WO2021193861A1

WO2021193861A1 - Heat-sensitive label and method for producing heat-sensitive label

Info

Publication number: WO2021193861A1
Application number: PCT/JP2021/012690
Authority: WO
Inventors: 岩瀬　祐一; 高広座間; 卓哉五十嵐
Original assignee: 株式会社ユポ・コーポレーション
Priority date: 2020-03-27
Filing date: 2021-03-25
Publication date: 2021-09-30
Also published as: JP7289011B2; JPWO2021193861A1

Abstract

The present invention provides: a heat-sensitive label which has few blisters; and a method for producing this heat-sensitive label.　A heat-sensitive label which comprises: a base material layer; and a heat seal layer that is arranged on the base material layer, while containing filler particles. The heat seal layer comprises: a first heat seal layer arranged on the base material layer; and a second heat seal layer arranged on the first heat seal layer. The filler particles are covered by the second heat seal layer; and the ten-point surface roughness Rz_JIS of the second heat seal layer is from 5 to 15 μm.

Description

Manufacturing method of thermal label and thermal label

The present invention relates to a heat-sensitive label and a method for manufacturing a heat-sensitive label.

In in-mold molding, in which resin is injected into the mold and molded, a heat-sensitive label may be inserted inside the mold and heat-sealed to the molded body by the heat of molding. In in-mold molding, if the air between the resin before molding and the label is difficult to escape, air remains between the molded body after molding and the label, and not only the adhesive strength of the label is lowered, but also the blister Appearance defects called can occur.

On the other hand, an in-mold label in which a specific uneven shape is provided by embossing on an adhesive layer to be adhered to a molded body has been proposed (see, for example, Patent Document 1). An air flow path is formed by the unevenness, and air can be discharged between the label and the molded product.

Japanese Unexamined Patent Publication No. 3-260689

The label is usually printed on the surface opposite to the surface that adheres to the molded product. If embossing is provided on the surface of the molded product as described above, the uneven shape of the embossing may be transferred to the printed surface when the labels are stacked. Therefore, a heat-sensitive label that can reduce blisters regardless of embossing has been developed.

An object of the present invention is to provide a thermal label having few blisters and a method for producing the same.

As a result of diligent studies to solve the above problems, the present inventors have found that the above problems can be solved if the heat-sealing layer on the molded body side contains filler particles and the heat-sealing layer has multiple layers. The invention was completed.
That is, the present invention is as follows.

(1) Base material layer and
It has a heat-sealing layer containing filler particles on the base material layer, and has
The heat seal layer has a first heat seal layer on the base material layer and a second heat seal layer on the first heat seal layer.
The filler particles are covered with the second heat seal layer,
_{A heat-sensitive label having a ten-point surface roughness Rz JIS of} the second heat-sealing layer of 5 to 15 μm.

(2) The second heat-sealing layer contains a heat-sealing resin, and the second heat-sealing layer contains a heat-sealing resin.
The heat-sensitive label according to (1) above, wherein the heat-sealed resin has a swell value of 0.5 to 1.6.

(3) The heat-sensitive label according to (1) or (2), wherein the content of the filler particles in the heat seal layer is 2.5 to 25% by mass.

(4) A support layer is provided between the first heat seal layer and the base material layer.
The first heat seal layer contains an ethylene resin and contains
The heat-sensitive label according to any one of (1) to (3) above, wherein the support layer contains a propylene resin.

(5) A step of forming a base material layer using the resin composition of the base material layer,
The resin compositions of the first heat seal layer and the second heat seal layer are co-extruded onto the base material layer, and the base material layer, the first heat seal layer, and the second heat seal layer are laminated in this order. Steps to obtain a laminated body
A step of stretching the laminate to obtain a heat-sensitive label containing the base material layer, the first heat-sealing layer and the second heat-sealing layer, and the like.
The resin composition of the first heat seal layer contains filler particles, and the resin composition of the second heat seal layer does not contain filler particles or contains 5% by mass or less of filler particles.
A method for producing a heat-sensitive label, wherein the ten-point surface roughness Rz _{JIS of the second heat seal layer is 5 to 15 μm.}

(6) In the step of obtaining the laminate, the resin composition of the support layer is coextruded together with the resin compositions of the first heat seal layer and the second heat seal layer, and the base material layer, the support layer, and the support layer are described. The method for producing a heat-sensitive label according to (5) above, wherein a laminate obtained by laminating the first heat-sealing layer and the second heat-sealing layer in this order is obtained.

(7) The method for producing a heat-sensitive label according to (5) or (6) above, wherein the content of the filler particles in the resin composition of the first heat seal layer is 5 to 50% by mass.

According to the present invention, it is possible to provide a thermal label having few blisters and a method for producing the same.

It is sectional drawing which shows the structure of the thermal label of one Embodiment of this invention.

Hereinafter, the thermal label of the present invention and the manufacturing method thereof will be described in detail. The following description is an example (representative example) of the present invention, and the present invention is not limited thereto.

In the following description, the description of "(meth) acrylic" indicates both acrylic and methacryl.

(Thermal label)
The heat-sensitive label of the present invention has a base material layer and a heat seal layer containing filler particles on the base material layer. The heat seal layer has a first heat seal layer and a second heat seal layer on the base material layer in this order. The filler particles are covered with a second heat-sealing layer, and the ten-point surface roughness Rz _{JIS of} the second heat-sealing layer is 5 to 15 μm. Usually, a printing layer is provided on the surface of the base material layer opposite to the heat-sealing layer.

By including the filler particles in the heat seal layer in this way, it is possible to provide fine irregularities with a _{ten-point surface roughness Rz JIS within a specific range on the surface of the heat-sensitive label.} Since the air flow path is formed even when the heat-sensitive label comes into contact with the molded body due to the unevenness, the air between the heat-sensitive label and the molded body can be discharged during in-mold molding to reduce the generation of blisters. Since the unevenness is finer and more irregular than when the unevenness is provided by embossing, even when the heat-sensitive labels are stacked, the uneven shape is not transferred to the printing layer on the opposite side of the heat seal layer, and the heat-sensitive shape is not transferred. The excellent appearance of the label is maintained.

On the other hand, when fine irregularities are provided by the filler particles, shavings are likely to occur. Mayani refers to agglomerates of particles that adhere to the lip of a molding machine over time when a heat seal layer is formed by extrusion molding. In general, eyelids due to agglutination of particles are likely to occur when forming a layer containing a large amount of filler particles. However, the resin used for the heat seal layer has a lower melt viscosity than the base material layer, and when it is melted by heating in the process of manufacturing the heat-sensitive label, the filler particles in the heat seal layer tend to move easily. Therefore, even if the content of the filler particles is small, a part of the filler particles can be aggregated and accumulated on the lip of the die, resulting in a shaving. If the Mayani falls off and remains as a foreign substance in the heat-sensitive label, it can be a factor that deteriorates the quality of the heat-sensitive label.

Therefore, if the heat seal layer contains filler particles, it is necessary to control the manufacturing process such as removing the meshi on a regular basis. However, the heat-sensitive label heat-sealing layer of the present invention has a first heat-sealing layer and a second heat-sealing layer, and is multi-layered. If the filler particles are mixed in the first heat-sealing layer, even if the filler particles move to the surface of the first heat-sealing layer, they are covered by the second heat-sealing layer. It is possible to prevent the dropout. Therefore, it is possible to continuously produce heat-sensitive labels with few blisters while suppressing the generation of eyebrows.

The heat-sensitive label of the present invention preferably has a support layer between the first heat seal layer and the base material layer.

FIG. 1 shows the configuration of the thermal label 10 as an embodiment of the present invention.
The heat-sensitive label 10 illustrated in FIG. 1 has a base material layer 1, a heat seal layer 2, and a support layer 3. The support layer 3 is arranged between the base material layer 1 and the heat seal layer 2. The heat seal layer 2 has a first heat seal layer 21 and a second heat seal layer 22 on the support layer 3 in this order. Further, the heat seal layer 2 contains the filler particles 4 covered with the second heat seal layer 22. A print layer 5 may be formed by printing on the surface of the base material layer 1 opposite to the heat seal layer 2.

Hereinafter, the configuration of the thermal label will be described.
<Base layer>
The substrate layer can impart mechanical strength to the thermal label. As a result, sufficient elasticity can be obtained when printing on the heat-sensitive label or when inserting the label into the mold, and excellent handleability can be obtained.

<< Thermoplastic resin >>
The base material layer contains a thermoplastic resin.
Examples of the thermoplastic resin include olefin resins, ester resins, amide resins, polyvinyl chloride resins, polystyrene resins, polycarbonate resins and the like. From the viewpoint of mechanical strength, the base material layer preferably contains an olefin resin or an ester resin as the thermoplastic resin, and more preferably contains an olefin resin. Of these, one type or a combination of two or more types can be used.

Examples of the olefin resin include propylene resin and ethylene resin. From the viewpoint of moldability and mechanical strength, a propylene resin is preferable.

The propylene-based resin is not particularly limited as long as propylene is used as the main monomer. For example, an isotactic polymer obtained by homopolymerizing propylene, a syndiotactic polymer, and the like can be mentioned. Further, it is a copolymer of propylene as a main component and an α-olefin such as ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-hexene, or 1-octene. Some propylene-α-olefin copolymers and the like can also be used. The copolymer may be a binary system in which the monomer component is a binary system or a plural system in which the monomer component is a ternary system or more, and may be a random copolymer or a block copolymer. Further, the propylene homopolymer and the propylene copolymer may be used in combination. Among these, the propylene homopolymer is preferable because it is easy to handle as the main raw material of the base material layer.

As the ethylene-based resin, for example high density polyethylene having a density of 0.940 ~ 0.965g / cm ^3, medium density polyethylene having a density of 0.920 ~ 0.935g / cm ^3, density of 0.900 ~ 0.920 g / to cm ³ straight chain linear low density polyethylene, ethylene or the like as a main component, propylene, butene, hexene, heptene, octene, 4-methylpentene copolymers α- olefin is copolymerized, such as -1, maleated Ethylene-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid alkyl ester copolymer, ethylene-methacrylic acid alkyl ester copolymer, ethylene-methacrylic acid copolymer Examples thereof include coalesced metal salts (metals are zinc, aluminum, lithium, sodium, potassium, etc.), ethylene-cyclic olefin copolymers, maleic acid-modified polyethylene, and the like.

Examples of the ester-based resin include polyethylene terephthalate resin, polybutylene terephthalate resin, and polyethylene naphthalate.
Examples of the amide resin include nylon-6, nylon-6,6, nylon-6,10, nylon-6,12 and the like.

The content of the thermoplastic resin in the base material layer is preferably 50% by mass or more, more preferably 70% by mass or more. When the content is 50% by mass or more, the mechanical strength of the base material layer is likely to be improved. On the other hand, there is no particular upper limit on the content of the thermoplastic resin, which may be 100% by mass, or less than 100% by mass with the addition of fillers and additives described below within a range that does not affect the strength or moldability. May be.

<< Filler >>
The base material layer can contain a filler. Due to the inclusion of the filler, pores are likely to be formed inside the base material layer during stretching, and the whiteness or opacity can be enhanced. In this case, the base material layer is a porous stretched layer.
Examples of the filler that can be used for the base material layer include an inorganic filler and an organic filler.

Examples of the inorganic filler include heavy calcium carbonate, light calcium carbonate, calcined clay, silica, diatomaceous earth, white clay, talc, titanium oxide such as rutile type titanium dioxide, barium sulfate, aluminum sulfate, zinc oxide, magnesium oxide, mica, and seri. Inorganic particles such as sight, bentonite, sepiolite, vermiculite, dolomite, wallastonite, and glass fiber can be mentioned. Among them, heavy calcium carbonate, clay or diatomaceous earth is preferable because the pores have good moldability and are inexpensive. The surface of the inorganic filler may be surface-treated with a surface treatment agent such as fatty acid for the purpose of improving dispersibility.

Organic fillers include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyamide, polycarbonate, polystyrene, cyclic olefin homopolymer, ethylene-cyclic olefin copolymer, polyethylene sulfide, polyimide, and poly, which are incompatible with olefin resins. Examples thereof include organic particles such as methacrylate, polyetheretherketone, polyphenylene sulfide, and melamine resin.
One of the above-mentioned inorganic fillers or organic fillers can be used alone or in combination of two or more.

From the viewpoint of increasing the whiteness or opacity of the base material layer, the content of the filler in the base material layer is preferably 10% by mass or more, more preferably 15% by mass or more. Further, from the viewpoint of enhancing the uniformity of molding of the base material layer, the content of the filler in the base material layer is preferably 70% by mass or less, more preferably 60% by mass or less, and 50% by mass or less. More preferred.

The average particle size of the inorganic filler or the organic filler is preferably 0.01 μm or more, more preferably 0.05 μm or more, still more preferably 0.1 μm or more, from the viewpoint of easiness of forming pores. From the viewpoint of imparting mechanical strength such as tear resistance, the average particle size of the inorganic filler or the organic filler is preferably 15 μm or less, more preferably 5 μm or less, still more preferably 2 μm or less.

The average particle size of the inorganic filler is 50% of the cumulative volume measured by a particle measuring device, for example, a laser diffraction type particle size distribution measuring device (Microtrac, manufactured by Nikkiso Co., Ltd.) (cumulative 50% particle size). It is D50. The average particle size of the organic filler is the average dispersed particle size when dispersed in the thermoplastic resin by melt-kneading and dispersion. The average dispersed particle size can be determined as an average value by observing the cut surface of the thermoplastic resin film containing the organic filler with an electron microscope and measuring the maximum size of at least 10 particles.

A known additive can be arbitrarily added to the base material layer, if necessary. Examples of the additive include antioxidants, light stabilizers, ultraviolet absorbers, dispersants of inorganic fine powders, lubricants such as higher fatty acid metal salts, anti-blocking agents such as higher fatty acid amides, dyes, pigments, plasticizers, and crystals. Examples include nuclear agents, mold release agents, and flame retardant agents.

When an antioxidant is added, a steric hindrance phenolic antioxidant, a phosphorus-based antioxidant, an amine-based antioxidant, or the like can usually be used within the range of 0.001 to 1% by mass. When a light stabilizer is used, a steric hindrance amine-based light stabilizer, a benzotriazole-based light stabilizer, or a benzophenone-based light stabilizer can be usually used in the range of 0.001 to 1% by mass. Dispersants or lubricants are used, for example, for the purpose of dispersing fillers. Specifically, a silane coupling agent, a higher fatty acid such as oleic acid or stearic acid, a metal soap, poly (meth) acrylic acid or a salt thereof, etc. are usually used within the range of 0.01 to 4% by mass. Can be done. These are preferably added within a range that does not impair the printability and heat sealability of the in-mold molding label made of a thermoplastic resin film.

<< Porosity >>
When the base material layer has pores inside, the porosity representing the ratio of pores in the layer is preferably 10% or more, more preferably 12% or more, from the viewpoint of obtaining opacity. It is preferably 15% or more, and more preferably 15% or more. From the viewpoint of maintaining the mechanical strength, the porosity is preferably 45% or less, more preferably 44% or less, and further preferably 42% or less. From the viewpoint of obtaining transparency, the porosity in the base material layer is preferably less than 10%, more preferably 5% or less, and further preferably 3% or less. The porosity may be 0%.
The porosity can be obtained from the ratio of the area occupied by the pores in a certain region of the cross section of the sample observed with an electron microscope.

The thickness of the base material layer is preferably 20 μm or more, more preferably 40 μm or more, from the viewpoint of layer strength. From the viewpoint of weight reduction of the thermal label, the thickness of the base material layer is preferably 200 μm or less, more preferably 150 μm or less.

The surface of the base material layer opposite to the heat seal layer may be surface-treated from the viewpoint of improving the adhesion to the printing layer. Further, a print receiving layer or the like having high adhesion to the printing layer may be provided on the surface of the base material layer opposite to the heat sealing layer.

<Heat seal layer>
The heat seal layer can enhance the adhesiveness with a molded body (adhesive body) such as a resin container. The heat seal layer is melted by heating, and the heat-sensitive label is heat-sealed on the surface of the molded product. When in-molding a molded product, a heat-sensitive label is provided inside the mold so that the molded product (container) and the heat seal layer face each other, and the heat of the parison or preform during in-mold molding is used. The heat seal layer is heat fused.

The heat seal layer has a multilayer structure, and has a first heat seal layer on the base material layer and a second heat seal layer on the first heat seal layer as described above. The heat seal layer contains filler particles, and the filler particles are covered with a second heat seal layer. The heat-sealing layer having such a multilayer structure is obtained, for example, after the resin composition for the first heat-sealing layer containing the filler particles and the resin composition for the second heat-sealing not containing the filler particles are co-extruded. Obtained by stretching.

The content of the filler particles in the heat seal layer is preferably 2.5% by mass or more, more preferably 3% by mass or more, still more preferably 5% by mass or more. , 25% by mass or less, more preferably 15% by mass or less, still more preferably 10% by mass or less. When the content is equal to or higher than the above lower limit value, blister is easily suppressed. When the content is not more than the above upper limit value, it is easy to reduce the shavings at the time of molding.

<< 1st heat seal layer >>
The first heat seal layer is formed by using a resin composition containing the first heat seal resin and filler particles. A part of the filler particles contained in the resin composition for the first heat seal layer protrudes from the first heat seal layer in the thickness direction by stretching, and contributes to the formation of the roughness of the surface of the heat seal layer.

<<< 1st heat seal resin >>>
From the viewpoint of obtaining sufficient adhesiveness even at low temperatures, the first heat-sealing resin preferably has a lower melting point than the thermoplastic resin used for the base material layer. Specifically, the melting point of the first heat-sealing resin is preferably 10 ° C. or higher, more preferably 20 ° C. or higher, and 30 ° C. or higher lower than the melting point of the thermoplastic resin used for the base material layer. Is even more preferable. As described above, since the first heat-sealing resin has a low melting point, even if the resin composition for the first heat-sealing layer contains filler particles, it does not become a porous layer by stretching like the base material layer.
The melting point can be measured by a differential scanning calorimetry (DSC).

From the viewpoint of moldability, the melting point of the first heat-sealing resin is preferably 60 ° C. or higher, more preferably 70 ° C. or higher. From the viewpoint of adhesiveness, the temperature is preferably 140 ° C. or lower, more preferably 120 ° C. or lower. When two or more kinds of first heat seal resins are used in combination, it is preferable that at least one kind has a melting point in the above range, and it is more preferable that all of them have a melting point in the above range.

Examples of the first heat-sealing resin include high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, ethylene / vinyl acetate copolymer, ethylene / (meth) acrylic acid copolymer, and ethylene / (. Metal selected from metal salts of polyethylene (meth) acrylic acid copolymer (alkyl group having 1 to 8 carbon atoms) and ethylene / (meth) acrylic acid copolymer (for example, Zn, Al, Li, K, Na). Resins such as (salt) and the like can be mentioned.

The first heat-sealing resin is a random copolymer or block of α-olefin obtained by copolymerizing at least two or more comonomer selected from α-olefin having 2 to 20 carbon atoms in the molecule. Examples include polymers.
Examples of α-olefins having 2 to 20 carbon atoms include ethylene, propylene, 1-butene, 2-methyl-1-propene, 1-pentene, 2-methyl-1-butene, 3-methyl-1-butene, and the like. 1-hexene, 2-ethyl-1-butene, 2,3-dimethyl-1-butene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 4-methyl- 1-hexene, 4,4-dimethyl-1-pentene, 3,3-dimethyl-1-butene, 1-heptene, methyl-1-hexene, dimethyl-1-pentene, ethyl-1-pentene, trimethyl-1- Butene, methylethyl-1-butene, 1-octene, 1-heptene, methyl-1-pentene, ethyl-1-hexene, dimethyl-1-hexene, propyl-1-heptene, methylethyl-1-heptene, trimethyl- Examples thereof include 1-pentene, propyl-1-pentene, diethyl-1-butene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, octadecene and the like. Among these, ethylene, propylene, 1-butene, 1-pentene, 1-hexene and 1-octene are preferable from the viewpoint of ease of copolymerization and economy.

Among these, low-density polyethylene, linear low-density polyethylene, ethylene / vinyl acetate copolymer, or metallocene catalyst was used for polymerization because it is easy to obtain a certain adhesive strength for various adherends. Polyethylene (metallocene-based polyethylene) is preferable, and low-density polyethylene or metallocene-based polyethylene is more preferable. On the other hand, the first heat-sealing resin preferably contains polyethylene and an ethylene-α-olefin copolymer from the viewpoint of obtaining excellent adhesive strength even when the adherend is polypropylene, and is a polyethylene and ethylene-propylene copolymer. It is more preferable to include. In this case, the mass ratio of the ethylene-α-olefin copolymer to polyethylene is preferably 10/90 to 50/50, more preferably 20/80 to 40/60.

<<< Filler particles >>>
As the filler particles to be blended in the resin composition of the first heat seal layer, the same material as the filler described in the base material layer can be used, and the preferred material is also the same. One of the above-mentioned inorganic filler and organic filler can be used alone or in combination of two or more.

The average particle size of the filler particles is preferably 2 μm or more, more preferably 4 μm or more, and even more preferably 6 μm or more. The average particle size is preferably 16 μm or less, more preferably 14 μm or less, and even more preferably 12 μm or less. When the average particle size is at least the above lower limit value, blister is easily suppressed, and when it is at least the above upper limit value, it is easy to suppress the dropout of filler particles and suppress the shavings.

The content of the filler particles in the resin composition of the first heat seal layer is preferably 5% by mass or more, more preferably 6% by mass or more, and further preferably 7% by mass or more. The content is preferably 50% by mass or less, more preferably 35% by mass or less, and further preferably 20% by mass or less. When the content is equal to or higher than the above lower limit value, blister is easily suppressed. When the content is not more than the above upper limit value, it is easy to reduce the shavings at the time of molding.

The average particle size of the filler particles can be selected according to the thickness of the first heat seal layer and the second heat seal layer.
Specifically, the difference (D50- (T1 + T2)) obtained by subtracting the sum of the thickness T1 of the first heat seal layer and the thickness T2 of the second heat seal layer from the average particle size D50 of the filler particles is 0.5 μm. The above is preferable, 1.0 μm or more is more preferable, and 3.0 μm or more is further preferable. The difference (D50- (T1 + T2)) is preferably 10 μm or less, more preferably 8 μm or less, and even more preferably 6 μm or less. When the difference (D50- (T1 + T2)) is equal to or greater than the above lower limit value, the ten-point average roughness Rz _JIS can be easily adjusted to the above range, and blister can be easily suppressed. Further, when the difference (D50- (T1 + T2)) is equal to or less than the above upper limit value, the filler particles are likely to be suppressed from falling off, and the occurrence of eyebrows is likely to be reduced.

Further, the difference (D80- (T1 + T2)) obtained by subtracting the total of the thickness T1 of the first heat seal layer and the thickness T2 of the second heat seal layer from the average particle size D80 of the filler particles is 2.5 μm or more. It is preferable, 4.0 μm or more is more preferable, and 5.0 μm or more is further preferable. The difference (D80- (T1 + T2)) is preferably 15 μm or less, more preferably 12 μm or less, and even more preferably 10 μm or less. When the difference (D80- (T1 + T2)) is equal to or greater than the above lower limit value, the ten-point average roughness Rz _JIS can be easily adjusted to the above range, and blister can be easily suppressed. Further, when the difference (D80- (T1 + T2)) is equal to or less than the above upper limit value, the filler particles are likely to be suppressed from falling off, and the occurrence of eyebrows is likely to be reduced.

The average particle size D80 is a volume average particle size (cumulative 80% particle size) that corresponds to 80% of the cumulative volume measured by a laser diffraction type particle size distribution measuring device (Microtrac, manufactured by Nikkiso Co., Ltd.).
Further, in the present specification, the thickness T1 of the first heat seal layer and the thickness T2 of the second heat seal layer refer to the thickness of the portion where the filler particles do not exist.

The first heat-sealing layer can optionally contain the known additives listed in the above-mentioned base material layer section, if necessary.
The blending ratio of these additives is preferably 0.05% by mass or more, preferably 0.5% by mass or more, based on the total solid content of the first heat seal layer, from the viewpoint of exhibiting the predetermined performance of the additives. The above is more preferable. On the other hand, from the viewpoint of ensuring the adhesive strength, the blending ratio of the additive is preferably 7.5% by mass or less, and more preferably 5% by mass or less, based on the total amount of solids in the heat seal layer. It is more preferably 3% by mass or less.

<< Second heat seal layer >>
The second heat seal layer is formed of a resin composition containing the second heat seal resin. The second heat seal layer covers the filler particles in the heat seal layer.

<<< Second heat seal resin >>>
As the second heat-sealing resin, the same thermoplastic resin as the first heat-sealing resin can be used. The second heat-sealing resin may be the same as or different from the first heat-sealing resin.

The second heat-sealing resin uses low-density polyethylene, linear low-density polyethylene, ethylene / vinyl acetate copolymer, or metallocene catalyst because it is easy to obtain a certain adhesive strength for various adherends. Polyethylene polymerized (metallocene-based polyethylene) is preferable, and low-density polyethylene or metallocene-based polyethylene is more preferable. On the other hand, the first heat-sealing resin preferably contains a polyethylene and an ethylene-α-olefin copolymer from the viewpoint of obtaining excellent adhesive strength even when the adherend is polypropylene, and is a polyethylene and ethylene-propylene copolymer. It is more preferable to include. In this case, the mass ratio of the ethylene-α-olefin copolymer to polyethylene is preferably 10/90 to 50/50, more preferably 20/80 to 40/60.

The swell value of the second heat-sealing resin is preferably 1.6 or less, more preferably 1.4 or less, and even more preferably 1.2 or less. When the swell value is 1.6 or less, the generation of shavings is likely to be suppressed during molding. The swell value is usually 0.5 or more, more preferably 0.7 or more, and even more preferably 0.9 or more.
The swell value is the ratio of the diameter of the melt of the resin extruded from the capillary to the diameter of the pores of the capillary, and can be measured by a capillary graph (1D, manufactured by Toyo Seiki Co., Ltd.). In the capillary graph, the hole diameter D of the capillary die is 1 mm, and the hole length L is 10 mm.

The melting point of the second heat-sealing resin is preferably lower than that of the thermoplastic resin of the base material layer, like the first heat-sealing resin. Specifically, the melting point of the second heat-sealing resin is preferably 60 ° C. or higher, more preferably 70 ° C. or higher, while it is preferably 140 ° C. or lower, more preferably 120 ° C. or lower. When two or more kinds of second heat-sealing resins are used in combination, it is preferable that at least one kind has a melting point in the above range, and it is more preferable that all of them have a melting point in the above range.

The second heat seal layer may contain the same filler particles as the first heat seal layer as long as the effects of the present invention are not impaired. From the viewpoint of suppressing the falling off of the filler particles and reducing the shavings, it is preferable that the resin composition of the second heat seal layer does not contain the filler particles. Specifically, the content of the filler particles in the resin composition of the second heat seal layer is 5% by mass or less, more preferably 3% by mass or less, further preferably 1% by mass or less, and 0% by mass. Especially preferable.

The second heat seal layer can contain an antistatic agent within a range that does not affect the heat seal performance from the viewpoint of handling such as transportability during printing. Suitable antistatic agents to be blended in the second heat seal layer include compounds having a primary to tertiary amine or quaternary ammonium salt structure, and complete fatty acids such as ethylene glycol, propylene glycol, glycerin, polyethylene glycol, and polyethylene oxide. Esters or partial fatty acid esters can be mentioned.

The content of the antistatic agent is preferably 0.01% by mass or more, preferably 0.05% by mass, with respect to the total solid content of the second heat seal layer, from the viewpoint of exhibiting the predetermined performance of the antistatic agent. % Or more is more preferable. On the other hand, from the viewpoint of ensuring the adhesive strength when the heat-sensitive label is attached to the plastic container, the content of the antistatic agent is preferably 3% by mass or less with respect to the total solid content of the heat seal layer. It is more preferably 2% by mass or less, and further preferably 1% by mass or less.

The second heat-sealing layer can optionally contain the known additives listed in the above-mentioned base material layer section, if necessary.
The content of these additives is preferably 0.05% by mass or more, preferably 0.5% by mass or more, based on the total solid content of the second heat seal layer from the viewpoint of exhibiting the predetermined performance of the additives. The above is more preferable. On the other hand, from the viewpoint of ensuring the adhesive strength, the content of the additive is preferably 7.5% by mass or less, more preferably 5% by mass or less, based on the total amount of solids in the heat seal layer. It is more preferably 3% by mass or less.

From the viewpoint of improving the adhesive strength and suppressing the peeling, the content of the second heat-sealing resin in the second heat-sealing layer is preferably 95% by mass or more, more preferably 97% by mass or more, still more preferably 99% by mass or more. ..

<< Thickness >>
The thickness (T1 + T2) of the heat seal layer including the first heat seal layer and the second heat seal layer is preferably 2 μm or more, more preferably 2.5 μm or more, still more preferably 3 μm or more. The same thickness (T1 + T2) is preferably 15 μm or less, more preferably 10 μm or less, and even more preferably 7.5 μm or less. When the thickness is at least the above lower limit value, the filler particles are suppressed from falling off and the generation of shavings is likely to be suppressed. If the thickness is equal to or less than the above upper limit, blister is likely to be suppressed.

From the viewpoint of suppressing blister, the thickness (T1) of the first heat seal layer is preferably smaller than the average particle size of the filler particles. Specifically, the thickness (T1) of the first heat seal layer is preferably 0.5 μm or more, more preferably 1.0 μm or more, and even more preferably 1.5 μm or more. The same thickness (T1) is preferably 10 μm or less, more preferably 7.5 μm or less, and even more preferably 5.0 μm or less. When the thickness (T1) is at least the above lower limit value, the thickness in the width direction (TD) is stable, and the smoothness and roughness of the surface of the heat seal layer, the adhesive strength, and the like are easily stabilized. When the thickness is not more than the above upper limit value, unevenness is likely to be formed, and blister and blocking are likely to be suppressed.

The thickness (T2) of the second heat seal layer is preferably 0.5 μm or more, more preferably 1.0 μm or more, and even more preferably 1.5 μm or more. The same thickness (T2) is preferably 10 μm or less, more preferably 7.5 μm or less, and even more preferably 5.0 μm or less. When the thickness (T2) is at least the above lower limit value, the filler particles are suppressed from falling off and the generation of shavings is likely to be suppressed. When the thickness (T2) is not more than the above upper limit value, unevenness is likely to be formed, and blister and blocking are likely to be suppressed.

<Support layer>
The support layer is coextruded onto the substrate layer together with the heat seal layer. A heat-sealing resin having a relatively low melting point is used for the heat-sealing layer, and extrusion molding may become unstable depending on the molding temperature, but stable molding is possible by co-extruding together with the support layer. .. Further, the support layer can suppress the migration of the filler particles in the resin composition of the first heat seal layer to the base material layer side, and the surface of the target ten-point surface roughness Rz _JIS is likely to be formed.

The support layer can be configured in the same manner as the base material layer. From the viewpoint of suppressing the migration of the filler particles to the base material layer side, the thermoplastic resin used for the support layer is preferably an olefin resin, and among the olefin resins, a propylene resin is preferable. The melting point of the thermoplastic resin is preferably higher than that of the first heat-sealing resin used for the first heat-sealing layer.

The thickness of the support layer is preferably 2 μm or more, more preferably 2.5 μm or more, and even more preferably 3 μm or more. The thickness is preferably 15 μm or less, more preferably 10 μm or less, and even more preferably 7.5 μm or less. When the thickness is at least the above lower limit value, the molding stability of the heat seal layer can be easily obtained.

(Manufacturing method of thermal label)
The heat-sensitive label of the present invention is produced by laminating a first heat-sealing layer and a second heat-sealing layer on a base material layer as follows, and stretching the obtained laminate.

<Step of forming the base material layer>
First, a base material layer is formed using the resin composition of the base material layer described above.
Examples of the method for forming the base material layer include extrusion molding (cast molding) with a T die, inflation molding with an O die, and calendar molding with a rolling roll.

From the viewpoint of improving the adhesion to the printing layer, the surface of the base material layer opposite to the heat-sealing layer may be surface-treated.
Examples of the surface treatment include corona discharge treatment, frame treatment, plasma treatment, glow discharge treatment, ozone treatment, and the like, and these treatments can be combined. Of these, corona discharge treatment or frame treatment is preferable, and corona treatment is more preferable.

The amount of discharge when the corona discharge treatment is carried out is preferably 600 J / m ² (10 W / min / m ² ) or more, and more preferably 1,200 J / m ² (20 W / min / m ² ) or more. On the other hand, it is preferably 12,000 J / m ² (200 W / min / m ² ) or less, and more preferably 10,800 J / m ² (180 W / min / m ² ) or less. When the frame processing is performed, the discharge amount is preferably 8,000 J / m ² or more, more preferably 20,000 J / m ² or more, and preferably 200,000 J / m ² or less, more preferably. It is preferably 100,000 J / m ² or less.

<Formation of heat seal layer>
Next, the resin compositions of the first heat seal layer and the second heat seal layer were co-extruded onto the base material layer, and the base material layer, the first heat seal layer, and the second heat seal layer were laminated in this order. To get.

As described above, the content of the filler particles in the resin composition of the first heat seal layer is preferably 5% by mass or more, more preferably 6% by mass or more, still more preferably 7% by mass or more. The content is preferably 50% by mass or less, more preferably 35% by mass or less, and further preferably 20% by mass or less. When the content is equal to or higher than the above lower limit value, blister is easily suppressed. When the content is not more than the above upper limit value, it is easy to reduce the shavings at the time of molding.
Further, as described above, it is preferable that the resin composition of the second heat seal layer does not contain filler particles, but when it is contained, the content of the filler particles in the resin composition of the second heat seal layer is 5% by mass. % Or less, and particularly preferably 0% by mass.

From the viewpoint of improving molding stability, the resin composition of the support layer can also be coextruded to obtain a laminate in which the base material layer, the support layer, the first heat seal layer and the second heat seal layer are laminated in this order. preferable.

In coextrusion molding, if the resin composition of each layer can be laminated in a film shape and extruded, cast molding, calendar molding, rolling molding, or Inflation molding or the like can be used.

Examples of the method for laminating the heat seal layer on the base material layer include an extrusion laminating method and a film bonding method.
In the extrusion laminating method, the base material layer is molded first, and the melted thermoplastic composition for the heat seal layer is coextruded and laminated, and niped with a roll while cooling. Therefore, the molding and laminating processes are separate steps. It is done in.
In the film bonding method, the base material layer and the heat seal layer are each film-molded, and the two are bonded together via a pressure-sensitive adhesive. Therefore, molding and laminating are performed in separate steps.

<Stretching step of laminated body>
The laminate is then stretched to obtain a heat sensitive label containing a substrate layer, a first heat seal layer and a second heat seal layer.
As a result of the thickness of each layer being reduced by stretching, the filler particles in the first heat seal layer protrude from the first heat seal layer, and the second heat seal layer is also pushed away to form an irregular and fine uneven shape on the surface. NS. Further, when the base material layer contains a filler, pores are likely to be formed in the base material layer by stretching.

As the stretching method, for example, a longitudinal stretching method using the peripheral speed difference of the roll group, a transverse stretching method using a tenter oven, a sequential biaxial stretching method combining these, a rolling method, and a simultaneous two stretching method using a combination of a tenter oven and a pantograph. Examples include a shaft stretching method and a simultaneous biaxial stretching method using a combination of a tenter oven and a linear motor. Further, a simultaneous biaxial stretching (inflation molding) method in which the molten resin is extruded into a tube shape using a circular die connected to a screw type extruder and then air is blown into the molten resin can also be used.

It is preferable that the base material layer, the first heat seal layer, and the second heat seal layer are stretched in at least one direction. From the viewpoint of improving the strength, the base material layer is more preferably stretched in two directions.

When the thermoplastic resin used is a non-crystalline resin, the stretching temperature at the time of performing stretching is preferably in the range of the glass transition temperature or higher of the thermoplastic resin. When the thermoplastic resin is a crystalline resin, the stretching temperature is at least the glass transition point of the non-crystalline portion of the thermoplastic resin and within the range of the melting point of the crystalline portion of the thermoplastic resin. Specifically, a temperature 2 to 60 ° C. lower than the melting point of the thermoplastic resin is preferable.

The stretching speed is not particularly limited, but is preferably in the range of 20 to 350 m / min from the viewpoint of stable stretch molding.
Further, the draw ratio can also be appropriately determined in consideration of the characteristics of the thermoplastic resin used. For example, when a thermoplastic resin film containing a homopolymer of propylene or a copolymer thereof is stretched in one direction, the draw ratio is usually 1.2 times or more, preferably 2 times or more at the lower limit. The upper limit is usually 12 times or less, preferably 10 times or less. On the other hand, in the case of biaxial stretching, the lower limit is usually 1.5 times or more, preferably 10 times or more, and the upper limit is usually 60 times or less, preferably 50 times or less. be.

When a thermoplastic resin film containing an ester resin is stretched in one direction, the upper limit of the draw ratio is usually 1.2 times or more, preferably 2 times or more, and the lower limit is usually 10 times or less. It is preferably 5 times or less. In the case of biaxial stretching, the lower limit of the area stretching ratio is usually 1.5 times or more, preferably 4 times or more, and the upper limit is usually 20 times or less, preferably 12 times or less.
Within the range of the draw ratio, the desired porosity can be obtained and the opacity can be easily improved. In addition, the thermoplastic resin film is less likely to break, and stable stretch molding tends to be possible.

(Physical characteristics of thermal label)
<< Ten-point average roughness >>
_{The ten-point average roughness Rz JIS} of the second heat seal layer of the heat-sensitive label of the present invention is 5 μm or more as described above, but is preferably 5.5 μm or more, and more preferably 6 μm or more. The 10-point average roughness is 15 μm or less, preferably 12 μm or less, and more preferably 10 μm or less. If the ten-point average roughness Rz _JIS is equal to or higher than the above lower limit, air between the molding resin and the heat-sensitive label is easily discharged when used as an in-mold label, and blister is easily suppressed and discharged. It is easy to suppress the decrease in adhesive strength due to the remaining air. When the ten-point average roughness Rz _JIS is not more than the above upper limit value, the adhesive strength with the container can be easily obtained.
The ten-point average roughness Rz _JIS is measured in accordance with JIS B0601: 2013 Annex 1.

<< Smoothness >>
The smoothness of the surface of the heat-sensitive label of the present invention on the second heat seal layer side is preferably 100 seconds or more, more preferably 200 seconds or more, preferably 1000 seconds or less, and more preferably 500 seconds or less. When the smoothness is equal to or less than the above upper limit value, air between the molding resin and the heat-sensitive label is easily discharged when used as an in-mold label, and blisters are easily suppressed. In addition, it is easy to suppress a decrease in adhesive strength due to the air remaining without being discharged. When the smoothness is equal to or higher than the above lower limit value, the adhesive strength with the container can be easily obtained.

(Print label)
<Print layer>
The printing layer is formed by printing with ink on the surface of the heat-sensitive label opposite to the heat-sealing layer.
Examples of the print information include photographic images, patterns, barcodes, manufacturers, sales company names, characters, product names, usage methods, and the like.

The printing method that can be used is not particularly limited, and examples thereof include gravure printing, offset printing, flexographic printing, letterpress printing, sticker printing, screen printing, and inkjet printing. Depending on the printing method, inks such as oil-based ink, oxidative polymerization curable ink, ultraviolet curable ink, water-based ink, and liquid toner ink can be used.

The heat-sensitive label and the printed label according to the present invention can be used as a label for in-mold molding (in-mold label).

(Labeled container)
The labeled container has a heat-sensitive label or a printed label of the present invention and a plastic container body. The heat-sensitive label or the printed label is attached to the plastic container body via the heat seal layer.

<Plastic container>
Examples of the material of the plastic container include polyester resins such as polyethylene terephthalate (PET) and its copolymers; polyolefin resins such as polypropylene (PP) and polyethylene (PE); and polycarbonate resins. Among them, since it is a resin that is easily blow-molded, it is preferable to use a polyester-based resin or a polyolefin-based resin, and it is more preferable to use a polyolefin-based resin. Further, it is preferable to use a thermoplastic resin composition containing these thermoplastic resins as a main component.

<Manufacturing method of labeled plastic container>
As for the labeled plastic container, a method of adhering the in-mold label to the container at the time of molding the plastic container can be mentioned in processes such as hollow molding, injection molding and differential pressure molding.

For example, in hollow molding, the in-mold label is arranged in the cavity of the molding die so that the surface of the label on the heat seal layer side faces the cavity side of the mold (the surface on the printing layer side is in contact with the mold). After that, it is fixed to the inner wall of the mold by suction or static electricity. Next, a resin parison or melt of preform, which is a container molding material, is guided between the molds. After molding, hollow molding is performed by a conventional method, and a labeled plastic container in which the label is integrally fused to the outer wall of the plastic container is molded.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples. In addition, the description of "part", "%", etc. in the Examples means the description of the mass standard unless otherwise specified.

Table 1 shows a list of materials used in Examples and Comparative Examples.

(Example 1)
The propylene homopolymer (PP1) shown in Table 1 (trade name: Novatec PP MA4, manufactured by Japan Polypropylene Corporation, melting point (JIS K7121): 167 ° C.) 99% by mass, inorganic filler (CA1) (heavy calcium carbonate, product). Name: Softon # 1800, manufactured by Bikita Powder Industry Co., Ltd., average particle size D50: 2.0 μm, average particle size D80: 4.4 μm) 1% by mass was mixed to prepare a resin composition (A) for the base material layer. bottom. A resin composition (B) for the support layer was prepared in the same manner as the resin composition (A). That is, the resin composition (B) of the support layer has the same material and content as the base material layer.

Metallocene polyethylene (PE1) shown in Table 1 (trade name: Engage 8411, manufactured by The Dow Company, swell value: 0.96, melting point (JIS K7121): 76 ° C.) 92% by mass, inorganic filler (CA2) ( Light calcium carbonate, trade name: CUBE-80KAS, manufactured by Maruo Calcium Co., Ltd., average particle size D50: 8.8 μm, average particle size D80: 11.0 μm) 8% by mass was mixed, and the resin composition of the first heat seal layer was mixed. (C) was prepared. Further, 100% by mass of metallocene-based polyethylene (PE1) was used as the resin composition (D) of the second heat-sealing layer.

The resin composition (A) of the base material layer was melt-kneaded by an extruder set at 250 ° C., then supplied to a T-die set at 250 ° C. and extruded into a sheet. This was cooled to about 60 ° C. with a cooling roll to obtain an unstretched sheet. The obtained unstretched sheet was reheated with a heat roll so that the temperature of the sheet surface became 140 ° C., and then stretched four times in the vertical direction by utilizing the difference in peripheral speed of the roll group. The sheet was cooled by a cooling roll until the temperature of the sheet surface reached about 60 ° C. to obtain a 4-fold stretched sheet.

Next, the resin compositions (B) to (D) were melt-kneaded by three other extruders set at 230 ° C., and then extruded into a sheet from a T-die set at 230 ° C., which was quadrupled. It was laminated on a stretched sheet. As a result, a laminated sheet having a four-layer structure in which the base material layer (A) / support layer (B) / first heat seal layer (C) / second heat seal layer (D) was laminated in this order was obtained. ..

The sheet of this laminated body was reheated using a tenter oven so that the temperature of the sheet surface became 160 ° C., then stretched 9 times in the lateral direction using a tenter, and further adjusted to 170 ° C. by a heat set zone. Annealing processing was performed. The film was cooled to about 60 ° C. with a cooling roll, and the ears were slit to obtain a biaxially stretched resin film having a four-layer structure. This was guided to a corona discharge processor with a guide roll, and the surface on the substrate layer side was subjected to a corona discharge treatment at a processing amount of ^{50 W / min / m 2.} The heat-sensitive label of Example 1 was obtained by winding with a winder.

The obtained heat-sensitive label has a total thickness of 100 μm, and has the number of stretched axes of each of the base material layer (A) / support layer (B) / first heat seal layer (C) / second heat seal layer (D). Was biaxial / uniaxial / uniaxial / uniaxial, and the thickness of each layer was 91 μm / 5 μm / 2 μm / 2 μm.

(Example 2)
In Example 1, the ethylene / propylene copolymer (PP2) shown in Table 1 in the resin composition (D) of the second heat-sealing layer (trade name: VISTAMAXX 3588FL, manufactured by ExxonMobil, swell value: 1.02). , Melting point (JIS K7121): 103 ° C.) was further added to obtain a heat-sensitive label of Example 2 in the same manner as in Example 1 except that the composition of the second heat seal layer was adjusted as shown in Table 2. ..

(Example 3)
In Example 2, except that the ethylene / propylene copolymer (PP2) was further added to the resin composition (C) of the first heat seal layer to adjust the composition of the resin composition (C) as shown in Table 2. Obtained the heat-sensitive label of Example 3 in the same manner as in Example 2.

(Example 4)
In Example 2, the inorganic filler of the resin composition (C) of the first heat seal layer was used as an organic filler (F1) (crosslinked polystyrene, trade name SSX-108, manufactured by Sekisui Plastics Co., Ltd., average particle size D50: 8. The heat-sensitive label of Example 4 was obtained in the same manner as in Example 2 except that the particle size was 8 μm and the average particle size was D80: 11.0 μm) 8% by mass.

(Comparative Example 1)
A heat-sensitive label of Comparative Example 1 was obtained in the same manner as in Example 1 except that the first heat-sealing layer having a thickness of 4 μm was formed without forming the second heat-sealing layer.

(Comparative Example 2)
In Example 2, the heat sensitivity of Comparative Example 2 was the same as in Example 2 except that the inorganic filler of the resin composition (C) of the first heat seal layer was replaced with 8% by mass of heavy calcium carbonate (CA1). Got a label.

(Comparative Example 3)
A heat-sensitive label of Comparative Example 3 was obtained in the same manner as in Example 2 except that the thicknesses of the first heat-sealing layer and the second heat-sealing layer were changed to 5 μm, respectively.

(Comparative Example 4)
In Comparative Example 2, the heat-sensitive label of Comparative Example 4 was obtained in the same manner as in Comparative Example 2 except that the thickness of the first heat-sealing layer was changed to 4 μm without forming the second heat-sealing layer.

(Comparative Example 5)
In Comparative Example 2, an inorganic filler (CA1) was added to the resin composition (D) of the second heat seal layer, and the composition of the resin composition (D) was adjusted as shown in Table 2. The heat-sensitive label of Comparative Example 5 was obtained in the same manner as in 2.

(Comparative Example 6)
In Comparative Example 1, a filler was not blended in the resin composition (C) of the first heat seal layer, and 100% by mass of metallocene-based polyethylene (PE) was used. 6 thermal labels were obtained.

(Physical characteristics of thermal label)
The thickness of the heat-sensitive label, the smoothness of the surface of the heat seal layer, and the ten-point average roughness of each Example and Comparative Example were measured as follows.

<Thickness>
The thickness (total thickness) of the heat-sensitive label was measured using a constant pressure thickness measuring device (product name: PG-01J, manufactured by Teclock Co., Ltd.) in accordance with JIS K7130: 1999. The thickness of each layer in the thermal label was determined as follows. The sample to be measured is cooled to a temperature of -60 ° C or less with liquid nitrogen, and a razor blade (product name: Proline Blade, manufactured by Schick Japan K.K.) is applied at a right angle to the sample placed on the glass plate to cut it. , A sample for cross-sectional observation was prepared. The cross section of the obtained sample was observed using a scanning electron microscope (product name: JSM-6490, manufactured by JEOL Ltd.), and the boundary line of each layer of the thermoplastic resin composition was discriminated from the appearance. The thickness ratio of each layer observed in the total thickness of the mold label was determined. This thickness ratio was multiplied by the measured total thickness to obtain the thickness of each layer.

<Smoothness>
According to JIS P 8155: 2010 "Paper and Paperboard-Smoothness Test Method-Oken Method", the surface of the heat seal layer of the heat-sensitive label is digitally Oken-type air permeability and smoothness tester (product name: EYO). -55-1M, manufactured by Asahi Seiko Co., Ltd.).

<10-point average roughness>
_{The surface roughness Rz JIS} of the surface of the heat seal layer of the heat-sensitive label was measured according to JIS B0601: 2013 Annex 1. Using a surface roughness measuring machine (product name: SURFCOM 1500DX, manufactured by Tokyo Seimitsu Co., Ltd.), the heat-sealed surface of the label cut into (50 mm × 50 mm) was measured with a measurement length of 30 mm.

(evaluation)
Using the heat-sensitive labels of each Example and Comparative Example as in-mold labels, a polypropylene resin container and a polyethylene resin container were each in-mold molded to produce a labeled container. Using these labeled containers, the heat-sensitive label blister, the adhesive strength to the molded product, and the meshi were evaluated as follows.

<Manufacturing of labeled molded parts (PP containers)>
The heat-sensitive label was punched into a rectangle having a width of 60 mm and a length of 120 mm. The heat-sensitive label after processing was placed on one of the blow molding dies capable of molding a bottle having a capacity of 0.4 L so that the heat seal layer faced the cavity side, and fixed on the dies using suction. ..

Propropylene homopolymer between molds (trade name: Novatec HD EG8B, manufactured by Japan Polypropylene Corporation, MFR (JIS K7210: 1999): 0.8 g / 10 minutes, density (JIS K7112: 1999): 0.90 g / cm ³ ) Was melted at 180 ° C. and extruded into a parison shape. The parison of the part to which the label is attached was set to 180 ° C. After the mold was molded, 4.2 kg / cm ² of compressed air was supplied into the parison, and the parison was expanded for 20 seconds to be brought into close contact with the mold to form a container and fused with the label. The molded product was then cooled in the mold and opened to obtain a labeled container. At this time, the mold cooling temperature was set to 20 ° C., and the shot cycle time was set to 31 seconds / time.

<Manufacturing of labeled molded parts (PE containers)>
The heat-sensitive label was punched into a rectangle having a width of 60 mm and a length of 120 mm. The heat-sensitive label after processing was placed on one of the blow molding dies capable of molding a bottle having a capacity of 0.4 L so that the heat seal layer faced the cavity side, and fixed on the dies using suction. ..

High-density polyethylene between molds (trade name: Novatec HD HB420R, manufactured by Japan Polyethylene Corporation, MFR (JIS K7210: 1999): 0.2 g / 10 minutes, density (JIS K7112: 1999): 0.956 g / cm ³ ) Was melted at 180 ° C. and extruded into a parison shape. The parison of the part to which the label is attached was set to 180 ° C. After the mold was molded, 4.2 kg / cm ² of compressed air was supplied into the parison, and the parison was expanded for 20 seconds to be brought into close contact with the mold to form a container and fused with the label. The molded product was then cooled in the mold and opened to obtain a labeled container. At this time, the mold cooling temperature was set to 20 ° C., and the shot cycle time was set to 31 seconds / time.

<Blister>
The appearance of the labeled PE container was visually observed, and the blisters due to insufficient adhesion and the blisters due to insufficient air bleeding were evaluated as follows.

<< Blister due to insufficient adhesion >>
〇: Blister due to insufficient adhesion is not recognized ×: Blister due to insufficient adhesion is recognized << Blister due to insufficient air release >>
〇: Blister due to insufficient air bleeding is not recognized ×: Blister due to insufficient air bleeding is recognized

<Adhesive strength>
The labeled container was stored for 1 week in an environment of 23 ° C. and 50% relative humidity. Then, according to JIS K 6854-3: 1999, the labeled portion of the labeled container was cut into strips having a width of 15 mm to prepare a sample. The sample is set in a tensile tester (Autograph AGS-D type, manufactured by Shimadzu Corporation), and the label is peeled off by pulling the label in a T shape at a tensile speed of 300 mm / min with the tensile tester to separate the label from the container. The adhesive strength between them was determined.

<Meyani>
The heat-sensitive label was continuously produced for 12 hours, and the surface of the obtained heat-sensitive label on the heat seal layer side was visually observed. When the shavings are generated on the lip of the die of the extrusion molding machine, the streaks associated with the shavings are generated on the surface of the heat-sensitive label. Therefore, the presence or absence of the shavings on the heat-sensitive label was observed and the occurrence of the shavings was evaluated as follows.
〇: No streaks are found on the heat-sensitive label after 12 hours, and there is no shavings, or even if shavings are occurring, it is a practical level. level

Table 2 shows the composition of each Example and Comparative Example. Table 3 shows the evaluation results.

According to Examples 1 to 4, no blisters were observed in any of the containers, and sufficient adhesive strength was obtained for both the PE container and the PP container. In addition, no shavings were generated even after continuous production for 12 hours.

On the other hand, in Comparative Example 1 in which the ten-point average roughness Rz _JIS is in a specific range, blister is not generated, but in Comparative Examples 2 to 4 outside the specific range, blister is generated and air is not sufficiently released. It turns out that there is. Further, in Comparative Examples 1, 4 and 5, eyebrows are generated. It is presumed that this is because there is no second heat seal layer covering the filler particles in the first heat seal layer, or the filler particles blended in the second heat seal layer have fallen off. In Comparative Example 6 in which the filler is not contained in the heat seal layer, no mayani is generated, but blister is also generated and air is not sufficiently released.

This application claims priority based on Japanese Patent Application No. 2020-058967, which is a Japanese patent application filed on March 27, 2020, and incorporates all the contents of the Japanese patent application.

10 ... Thermal label, 1 ... Base material layer, 2 ... Heat seal layer, 21 ... 1st heat seal layer, 22 ... 2nd heat seal layer, 3 ... Support layer, 4 ... Filler particles, 5 ... Printing layer

Claims

Base layer and
It has a heat-sealing layer containing filler particles on the base material layer, and has
The heat seal layer has a first heat seal layer on the base material layer and a second heat seal layer on the first heat seal layer.
The filler particles are covered with the second heat seal layer,
A heat-sensitive label having a ten-point surface roughness Rz JIS of the second heat-sealing layer of 5 to 15 μm.
The second heat-sealing layer contains a heat-sealing resin and contains
The heat-sensitive label according to claim 1, wherein the heat-sealed resin has a swell value of 0.5 to 1.6.
The heat-sensitive label according to claim 1 or 2, wherein the content of the filler particles in the heat seal layer is 2.5 to 25% by mass.
A support layer is provided between the first heat seal layer and the base material layer.
The first heat seal layer contains an ethylene resin and contains
The heat-sensitive label according to any one of claims 1 to 3, wherein the support layer contains a propylene-based resin.
The step of forming the base material layer using the resin composition of the base material layer,
The resin compositions of the first heat seal layer and the second heat seal layer were co-extruded onto the base material layer, and the base material layer, the first heat seal layer, and the second heat seal layer were laminated in this order. Steps to obtain a laminate and
A step of stretching the laminate to obtain a heat-sensitive label containing the base material layer, the first heat-sealing layer and the second heat-sealing layer, and the like.
The resin composition of the first heat seal layer contains filler particles, and the resin composition of the second heat seal layer does not contain filler particles or contains 5% by mass or less of filler particles.
A method for producing a heat-sensitive label, wherein the ten-point surface roughness Rz JIS of the second heat seal layer is 5 to 15 μm.
In the step of obtaining the laminate, the resin composition of the support layer is coextruded together with the resin composition of the first heat seal layer and the second heat seal layer, and the base material layer, the support layer, and the first heat seal are obtained. The method for manufacturing a heat-sensitive label according to claim 5, wherein a laminate obtained by laminating the layers and the second heat-sealing layer in this order is obtained.
The method for producing a heat-sensitive label according to claim 5 or 6, wherein the content of the filler particles in the resin composition of the first heat seal layer is 5 to 50% by mass.