JP2011037466A - Packaging molded body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a packaging molded body capable of satisfying the see-through property and the blocking resistance of a resin film in applications in which a window hole is covered with the resin film from the inner side of the packaging molded body, and a heat-adhesive layer and a paper surface are heat-adhered to and joined with each other. <P>SOLUTION: In the packaging molded body having a paper-made envelope shape or a box shape having a window hole 30 with the window hole being covered with a resin film, a part of or the whole of the window hole, and its peripheral paper part are covered from the inner side of the packaging molded body with a heat-adhesive film in which a heat-adhesive layer as a surface layer and an unoriented polyolefin layer as a base layer are piled up on each other, and the heat-adhesive layer side of the heat-adhesive film is heat-adhered to the peripheral paper part. The heat-adhesive layer consists of at least one kind of copolymer to be selected from (A) ethylene-&alpha;-olefin copolymer polymerized by using a single site catalyst, (B) ethylene-vinyl acetate copolymer, and (C) ethylene-(meth) acrylic ester copolymer. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a paper envelope-shaped or box-shaped molded body having a window hole.

  2. Description of the Related Art Conventionally, a method of coating a window hole provided on a paper surface with a resin fill in a molded body for packaging such as an envelope or a tissue box.

  For example, an envelope with a window has a window on the cover, and a rectangular synthetic resin transparent sheet is attached to the window from the back side of the cover. When an envelope with a window is used, by inserting a sheet into the envelope, the window of the envelope with the window can see through the destination printed on the sheet. By using such an envelope with a window, it is possible to save the trouble of printing a destination address on the cover of the envelope.

  For coating the window holes with the resin film, a method of coating the resin film from the inside of the packaging molded body and a method of coating the resin film from the outside of the packaging molded body are used.

  In the method of coating the resin film from the inside of the packaging molded body, conventionally, the resin film is coated from the inside of the packaging molded body, part or all of the window hole, and the peripheral paper portion thereof, The peripheral part of the window hole and the resin film were adhered by an adhesive.

  However, with this method, a slight amount of solvent remains in the finished product, leaving an odor. Also, it is difficult to increase the processing speed for attaching the film due to the poor workability and operability of hot melt and solvent type adhesives. There were problems such as product defects such as adhesive sticking out and processing problems such as sticky adhesive spillage.

  In the method of coating the resin film from the outside of the packaging molded body, if only the window hole and its peripheral paper portion are coated, in addition to the above problems, a step is generated on the surface of the packaging molded body, and adhesion is also caused. Since the agent becomes visible, it is unsightly and the value as a product is low.

  Therefore, a technique has been used in which a thermal adhesive layer is formed on the resin film, the entire paper surface including the window holes is covered, and the resin film is integrated with the entire paper surface by thermal bonding.

  However, conventional materials that exhibit thermal adhesiveness to paper tend to be sticky, causing problems in workability such as problems due to blocking.

  Patent Document 1 also discloses a method of embossing a heat-adhesive layer that is heat-adhered to paper so as to make it difficult to block in order to solve the above problems. However, when embossing is performed, the light diffusibility is increased, and the transparency of the window hole is deteriorated. In order to eliminate embossing, there are cases where prescriptions such as applying heat to the resin film to flatten the embossing are incorporated into the process, but there are limits to flattening, and the number of processes is increasing. Therefore, the cost is low and the efficiency is low.

  Further, in such a method for covering the entire paper surface, the cost of the resin is high, and it is difficult to separate the resin film from the paper, so that it is difficult to separate dust.

Thus, in the past, serious problems remain in both the method of coating a resin film from the inside of a packaging molded body and the method of coating a resin film from the outside of a packaging molded body.
JP-A-6-143518

  This inventor examined the method of coat | covering a resin film from the inner side of the molded object for packaging with respect to a window hole.

  First, when a conventional resin film having a thermal adhesive layer is used for coating a window hole and its periphery from the inside of a packaging molded body, as in the case of coating from the outside described above, it is a defect due to blocking. Occurred.

  Furthermore, the present inventor has a problem peculiar when coating from the inside of the packaging molded body, that is, the thermal adhesive layer is exposed on the surface of the window hole of the packaging molded body. It has been found that the property greatly affects the transparency of the entire film.

  When the fluoroscopic object is seen through the resin film having the light scattering layer, the distance between the light scattering layer and the fluoroscopic object is important in the transparency. That is, as the distance increases, the fluoroscopic object is observed more unclearly.

  When the thermal adhesive layer of the resin film is oriented on the window hole surface side of the packaging molded body, even if the fluoroscopic object enclosed in the packaging molded body is in contact with the resin film, The distance between the thermal adhesive layer and the fluoroscopic object is ensured by the film thickness. Therefore, when the light scattering property of the heat bonding layer is high, the transparency of the entire film is remarkably lowered.

  Since such a phenomenon is remarkably exhibited as compared with the case where the molded body for packaging is coated from the outside, for example, when the embossing as in Patent Document 1 is applied to the thermal adhesive layer, the film is seen through. The properties are significantly reduced.

  If the embossing is not used or the transparency of the thermal adhesive layer is improved by reducing the embossing roughness, the blocking resistance will be further reduced, and there will be defects due to wrinkles and film cutting. appear.

  Even if embossing is not used, if the resin film having a high light scattering property of the thermal adhesive layer is used for coating from the inside of the molded article for packaging, a reduction in transparency is amplified.

  Although it is conceivable to improve the transparency by reducing the film thickness of the film, the film properties such as strength may be impaired, and it does not lead to a fundamental solution.

  Therefore, an object of the present invention is to cover the resin film with a window hole from the inside of the molded article for packaging and to thermally bond and bond the thermal adhesive layer and the paper surface. An object of the present invention is to provide a packaging molded body satisfying both properties.

  Other problems of the present invention will become apparent from the following description.

  The above problems are solved by the following inventions.

(Claim 1)
In a paper envelope-shaped or box-shaped packaging molded body having a window hole and covering the window hole with a resin film,
A part or all of the window hole and its peripheral paper part are covered from the inside of the molded article for packaging by a heat-adhesive film formed by laminating a heat-adhesive layer as a surface layer and an unstretched polyolefin layer as a base layer. And thermally bonding the thermal adhesive layer side of the thermal adhesive film to the peripheral paper part,
The molded article for packaging, wherein the thermal adhesive layer is made of at least one copolymer selected from the following (A) to (C).
(A) Ethylene / α-olefin copolymer polymerized using a single site catalyst (B) Ethylene / vinyl acetate copolymer (C) Ethylene / (meth) acrylic acid ester copolymer

(Claim 2)
The packaging material according to claim 1, further comprising an intermediate layer made of polyolefin between the thermal adhesive layer and the unstretched polyolefin layer, wherein the melting point of the unstretched polyolefin layer is higher than that of the intermediate layer. Molded body.

(Claim 3)
The molded article for packaging according to claim 1 or 2, wherein a Haze value of the thermal adhesive film is 20% or less.

(Claim 4)
The molded body for packaging according to any one of claims 1 to 3, wherein the thermal bonding portion of the peripheral paper portion is formed in a broken line shape or a dot shape.

  According to the present invention, the resin film is coated on the window hole from the inside of the packaging molded body, and the window hole is formed without using an adhesive in an application in which the thermal adhesive layer and the paper surface are bonded by thermal bonding. It is possible to obtain a molded product in which a film is pasted on paper having no odor of residual solvent, and no adhesive is used in processing the molded product, leading to an increase in processing speed. In addition, blocking resistance in thermal bonding is improved, and occurrence of troubles and defects is suppressed.

  Moreover, according to this invention, the molded object for packaging excellent in the transparency of the resin film is provided.

  Furthermore, according to the present invention, there is provided a molded body for packaging which can be easily separated from paper after use and can be neatly separated by making the thermal bonding portion linear, broken line or dot.

Sectional drawing of the principal part of the molded object for packaging which concerns on one Embodiment of this invention The figure which shows the example of formation of a heat bonding part The figure which shows an example of the molded object for packaging

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view of an essential part of a packaging molded body according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a packaging molded body, which is formed of a heat-adhesive film 2 and a paper 3 having a window hole. The thermal adhesive film 2 is formed by laminating a thermal adhesive layer 21, an intermediate layer 22, and a base layer 23. The thermal adhesive film 2 covers the window hole 30 provided in the paper 3 and the peripheral paper portion 31 thereof, and the peripheral paper portion 31 and the thermal adhesive layer 21 of the thermal adhesive film 2 are joined by thermal adhesion. ing.

  The paper 3 used in the present invention is not particularly limited, and general-purpose paper can be used. However, depending on the application, if it is too thin, the purpose is not achieved, and if it is too thick, the cost may increase. Is preferable.

Specifically, if the envelope is preferably 10 g / ^{m 2} or more in the basis weight, particularly preferably more preferably if 15 g / ^{m 2} or more, so maintained sufficient strength if 20 g / ^{m 2} or more. For tissue paper boxes, thicker paper is preferred for use as a box, and the basis weight is preferably 20 g / m ² or more, more preferably 25 g / m ² or more, and 30 g / m ² or more to maintain sufficient strength. Particularly preferred.

  The formation of the window hole 30 is not particularly limited, but the tissue paper box is formed with a window for the purpose of taking out the tissue, and for envelopes, the window has an appropriate size at an appropriate position as a window for internal visibility. It is preferable to provide it.

  Next, the thermal adhesive film used in the present invention will be described.

  The thermal adhesive film is formed by laminating at least a thermal adhesive layer as a surface layer and an unstretched polyolefin layer as a base layer, and an intermediate layer may be provided as necessary.

The material of the thermal adhesive layer is composed of at least one copolymer selected from the following (A) to (C).
(A) Ethylene / α-olefin copolymer polymerized using a single site catalyst (B) Ethylene / vinyl acetate copolymer (C) Ethylene / (meth) acrylic acid ester copolymer

  The material of the thermal adhesive layer is solid at room temperature, and functions appropriately if thermal adhesiveness to the peripheral paper portion 31 of the window hole 30 can be expressed by thermal adhesive processing below the melting point of the unstretched polyolefin layer (base layer). To express.

  Moreover, it is also preferable to increase the polarity of the surface by applying corona treatment to the surface of the thermal bonding layer 21 to improve the adhesion of the window hole 30 to the peripheral paper portion 31.

  The (A) ethylene / α-olefin copolymer constituting the heat-adhesive layer 21 of the heat-adhesive film of the present invention comprises ethylene polymerized using a single site catalyst and an α-olefin having 3 to 12 carbon atoms. A copolymer is preferred.

  The single-site catalyst refers to a catalyst constituted by substantially homogeneous polymerization active sites. Specifically, a metallocene-based transition metal compound (so-called Kaminsky catalyst) or a non-metallocene-based transition metal compound ( A polymerization catalyst comprising a Brookhart catalyst, a phenoxyimine complex, etc.) and a cocatalyst (methylaluminoxane, boron compound, etc.) can be used. As the most preferable single site catalyst, a metallocene catalyst having a metallocene-based transition metal compound as a main component can be exemplified. As the metallocene catalyst, a non-bridged metallocene catalyst such as biscyclopentadienylzirconium dichloride or a substituted product thereof can also be used.

The α-olefin of the ethylene / α-olefin copolymer used in the present invention is preferably an α-olefin having 3 to 12 carbon atoms. Specifically, propylene, 1-butene, 1
-Pentene, 1-hexene, 1-octene and the like can be mentioned. The content of α-olefin in the ethylene / α-olefin copolymer is preferably 5 to 40% by weight, more preferably 7 to 35% by weight. When the α-olefin content is low, the impact strength and low-temperature heat sealability of the film cannot be obtained, and when it is too high, the blocking resistance is impaired. The α-olefin content is measured by a ¹³ C-NMR method.

  Polymerization using a single site catalyst for obtaining an ethylene / α-olefin copolymer can be performed by the same method as described in the section of the propylene / α-olefin copolymer of the base layer 23.

  The metallocene ethylene / α-olefin copolymer may be appropriately selected from those commercially available as metallocene polyethylene. Examples of commercially available products include the product names “Kernel” and “Harmolex” manufactured by Nippon Polyethylene, and the product names “Affinity” manufactured by DuPont Dow. The ethylene / α-olefin copolymer may be used singly or as a mixture of two or more thereof, and blending with other polyethylene, particularly high-pressure low-density polyethylene is also a preferred embodiment.

  The ethylene / α-olefin copolymer used in the present invention is preferably a copolymer satisfying the following characteristics.

  A larger MFR (190 ° C., 21.18 N load) is preferable because it has the advantage of being able to get into the gap between the fibers of the paper during the thermal bonding process and obtain high adhesion, specifically 0.1 g / 10 minutes or more is preferable, 1 g / 10 minutes or more is more preferable, and 4 g / 10 minutes is particularly preferable because it sufficiently penetrates. Further, a smaller value is preferable because the film forming processability is stable. Specifically, 20 g / 10 min or less is preferable, 15 g / 10 min or less is more preferable, and 10 g / 10 min or less is workability. Is particularly preferred since it is stable. In addition, the measurement of MFR is performed based on JIS-K6921-2: 1997 appendix (190 degreeC, 21.18N load).

The density of the ethylene / α-ethylene copolymer used in the present invention is not particularly limited. However, when a molded article for packaging is produced by thermal bonding with paper, a lower temperature allows low-temperature thermal bonding or is higher. preferably since advantages such as resulting adhesion is exhibited, preferably 0.925 g / cm ³ or less and specifically more preferably if 0.915 g / cm ³ or less, if 0.905 g / cm ³ or less In particular, low temperature thermal bonding is particularly preferable because sufficient thermal bonding can be obtained. Also, better to some extent higher, preferably it is possible to suppress the processability problems due to blocking, preferably 0.870 g / cm ³ or more in particular, more preferably as long as 0.880 g / cm ³ or more, 0.885 g / cm Since it can process suitably if it is ³ or more, it is especially preferable. In addition, a density is measured based on the case of the low density polyethylene of JIS-K6922-2: 1997 appendix (23 degreeC).

  The resin component constituting the ethylene / α-olefin copolymer of the present invention can be blended with other additional optional components as long as the effects of the present invention are not significantly impaired. Examples of such optional components include antioxidants, crystal nucleating agents, clearing agents, lubricants, antiblocking agents, antistatic agents, antifogging agents, neutralizing agents, and metal inertness used in ordinary polyolefin resin materials. Agents, fluorescent whitening agents, and the like.

  The thermal adhesive layer 21 of the heat-adhesive release film 2 of the present invention can also use (B) an ethylene / vinyl acetate copolymer, and the ethylene / vinyl acetate copolymer may be based on a tubular system. An autoclave method may be used.

  The vinyl acetate content of the ethylene / vinyl acetate copolymer is preferable for thermal adhesion to paper because it has the advantage that low temperature thermal adhesion is possible and high adhesion is achieved. Specifically, it is preferably 3% by weight or more, more preferably 5% by weight or more, and particularly preferably 7% by weight or more because sufficient thermal bonding can be obtained even by low-temperature thermal bonding. Further, it is preferable that the amount is small to some extent, since workability problems due to blocking can be suppressed. Specifically, it is preferably 30% by weight or less, more preferably 25% by weight or less, and preferably 20% by weight or less. Therefore, it is particularly preferable.

  The MFR (190 ° C., 21.18N load) of the ethylene / vinyl acetate copolymer is preferable because it has a certain advantage that it can bite into the gap between the fibers of the paper at the time of heat bonding processing and obtain high adhesion. Specifically, 1 g / 10 min or more is preferable, 2 g / 10 min or more is more preferable, and 4 g / 10 min is particularly preferable because it sufficiently penetrates. Further, a smaller value is preferable because the film forming processability is stable. Specifically, 20 g / 10 min or less is preferable, 15 g / 10 min or less is more preferable, and 10 g / 10 min or less is workability. Is particularly preferred since it is stable.

  For the thermal adhesive layer 21 of the thermal adhesive release film 2 of the present invention, (C) ethylene / (meth) acrylic ester copolymer (EEA) can also be used.

  The ethylene / (meth) acrylic acid ester copolymer (EEA) is a copolymer having ethylene and acrylic acid, methacrylic acid, acrylic acid ester and / or methacrylic acid ester as a copolymerization component. As a copolymerization ratio, the (meth) acrylic acid comonomer is preferably 5% by weight to less than 50% by weight, more preferably 10 to 40% by weight, and further preferably 15 to 40% by weight. If it is less than 5%, sufficient adhesive strength cannot be obtained, and if it exceeds 50%, handling as a resin tends to be difficult.

  By applying a corona treatment to the surface of the thermal adhesive layer 21 of the present invention, the adhesive strength to paper is improved, and it can be integrated into a molded body for packaging having window holes.

  As conditions for the corona treatment, the wetting tension according to JIS K 6768 is preferably 36 mN / m or more, more preferably 38 mN / m or more, and 40 mN / m or more, so that sufficient adhesion can be easily obtained. This is particularly preferable.

  If the thermal adhesive layer is a thermal adhesive film formed from at least one copolymer selected from the above (A) to (C), the blocking resistance is improved and the adhesiveness is excellent. A good molded body for packaging can be obtained without embossing as used in Patent Document 1. Further, since the light scattering property of the surface of the thermal adhesive layer is low, the transparency is high when it is used for the window hole of the packaging molded body, and further, the effect that the surface is not sticky is exhibited.

  In this invention, an intermediate | middle layer can also be provided between a heat bonding layer and a base layer as needed, such as processing stability provision at the time of film forming.

  The intermediate layer is preferably composed mainly of polyolefin, and specifically, polypropylene, high-density polyethylene, low-density polyethylene, linear low-density polyethylene, and the like can be raised.

Especially when requiring transparency, generally the density is low polyethylene preferably, is preferably less than 0.940 g / cm ³ in particular, more preferably less than 0.935 g / cm ^3, is less than 0.930 g / cm ³ It is particularly preferable because sufficient transparency can be obtained.

  Furthermore, other thermoplastic resins can be added to the intermediate layer of the present invention.

  In the present invention, the base layer is formed from unstretched polyolefin. Specific examples include polypropylene, high density polyethylene, low density polyethylene, linear low density polyethylene, and the like, and the base layer formed by these is used in an unstretched state.

  In the conventional technical common sense including Patent Document 1, it is considered that the blocking is induced by the properties of the thermal adhesive layer, and the resin film has been improved based on this finding.

  On the other hand, the present inventor has intensively studied not only the thermal adhesive layer but also the base layer (surface layer on the side opposite to the thermal adhesive layer) as a factor causing blocking. As a result, by forming the stretched film in the base layer, the surface smoothness is improved more than necessary and blocking is induced, and the construction of a highly polar material such as polyethylene terephthalate in the base layer is blocking. The present invention was completed by finding that it was induced.

  That is, in the present invention, non-polar polyolefin is used in the base layer in an unstretched state, thereby suppressing blocking and improving blocking resistance. Therefore, it is not necessary to apply embossing with poor transparency to the thermal adhesive layer.

  In the present invention, the base layer preferably has a melting point higher than that of the thermal adhesive layer, and when the intermediate layer is provided, the base layer preferably has a melting point higher than that of the intermediate layer.

  Thus, in the process of thermally bonding the heat-adhesive film and paper, by providing this base layer, it is possible to suppress deformation due to heat, and to enable higher temperature processing and increase the adhesive strength with paper. it can.

As the structure of the base layer, when an intermediate layer is provided, the melting point is preferably higher than the components of the intermediate layer, specifically, it is preferably 10 ° C. or higher, more preferably 20 ° C. or higher. High density polyethylene and / or polypropylene can be suitably used as a component that easily satisfies these conditions. Depending on the combination of the selection of the intermediate layer is specifically as high density polyethylene, 0.920 g / cm ³ or more, more preferably as long as 0.930 g / cm ³ or more, 0.940 g / If it is cm ³ or more, it is more preferable, and 0.950 g / cm ³ or more is particularly preferable because sufficient heat resistance can be expected.

  In the case of using polypropylene, either a polypropylene based on a normal Ziegler catalyst or a propylene / α-olefin copolymer obtained using a single site catalyst can be selected.

  As the propylene / α-olefin copolymer used in the present invention, a random copolymer of propylene and an α-olefin other than propylene whose main component is a structural unit derived from propylene is used. The α-olefin used as a comonomer is preferably ethylene or an α-olefin having 4 to 18 carbon atoms. Specifically, ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-heptene, 4-methyl-pentene-1, 4-methyl-hexene-1, 4,4-dimethylpentene- 1 etc. can be mentioned.

The amount of α-olefin units in the propylene / α-olefin copolymer is usually 0.5 to 12% by weight, preferably 1 to 10% by weight. When there are many α-olefin units, the rigidity of the film is reduced and the film is easily scratched, and when it is too small, the flexibility and transparency are impaired. The propylene unit and the α-olefin unit can be measured by a ¹³ C-NMR method.

  The propylene / α-olefin copolymer used in the present invention is obtained by a single site catalyst. The single-site catalyst refers to a catalyst constituted by substantially homogeneous polymerization active sites. Specifically, a metallocene-based transition metal compound (so-called Kaminsky catalyst) or a non-metallocene-based transition metal compound ( A polymerization catalyst comprising a Brookhart catalyst, a phenoxyimine complex, etc.) and a cocatalyst (methylaluminoxane, boron compound, etc.) can be used. As the most preferable single site catalyst, a metallocene catalyst having a metallocene-based transition metal compound as a main component can be exemplified. The metallocene catalyst includes a transition metal compound of Group 4 of the periodic table containing a ligand having a cyclopentadienyl skeleton (so-called metallocene compound), a cocatalyst that can react with the metallocene compound and be activated to a stable ionic state, A catalyst comprising an organoaluminum compound added if necessary is used.

  The metallocene compound is preferably a bridged metallocene compound capable of stereoregular polymerization of propylene, and more preferably a bridged metallocene compound capable of isoregular polymerization of propylene. Specifically, alkylene biscyclopentadienyl zirconium dichloride, or a substituted product thereof such as methylene biscyclopentadienyl zirconium dichloride, ethylene bis (2-alkylindenyl) zirconium dichloride, ethylene 1,2- (4-phenyl). Indenyl) (2-methyl-4-phenyl-4Hazurenyl) zirconium dichloride, isopropylidene (cyclopentadienyl) (fluorenyl) zirconium dichloride, dimethylsilylene (2-methyl-4-t-butyl-cyclopentadienyl) (3′-t-butyl-5′-methyl-cyclopentadienyl) zirconium dichloride, dimethylsilylene (fluorenyl) t-butylamidozirconium dichloride, dimethylsilylenebis [1- (2-methyl-4 Phenyl -4H- azulenyl)] zirconium compounds such as zirconium dichloride can be exemplified. Also, compounds in which zirconium is replaced with titanium or hafnium can be used in the same manner, and chlorides are other halogen compounds, hydrocarbon groups such as methyl, isobutyl, and benzyl, amide groups such as dimethylamide and diethylamide, methoxy groups, phenoxy groups, etc. Can be replaced with an alkoxide group, a hydride group, or the like.

  Co-catalysts that can react with metallocene compounds to be activated to a stable ionic state include organoaluminum oxy compounds (eg, aluminoxane compounds), ion-exchange layered silicates, Lewis acids, boron-containing compounds, ionic compounds, fluorine-containing An organic compound etc. are mentioned.

  Examples of the organoaluminum compound include trialkylaluminum such as triethylaluminum, triisopropylaluminum, and triisobutylaluminum, dialkylaluminum halide, alkylaluminum sesquihalide, alkylaluminum dihalide, alkylaluminum hydride, and organoaluminum alkoxide.

  Examples of the polymerization method include a slurry method using an inert solvent in the presence of the catalyst, a solution method, a gas phase method substantially using no solvent, or a bulk polymerization method using a polymerization monomer as a solvent. It is done.

  As the propylene / α-olefin copolymer obtained by the single site catalyst, a commercially available one can be used. For example, a propylene-ethylene random copolymer manufactured by Nippon Polypro Co., Ltd., trade name “Wintech” ( Wintech is a registered trademark of Nippon Polypro Co., Ltd.).

The propylene / α-olefin copolymer used in the present invention preferably has the following characteristics.
The MFR (230 ° C., 21.18 N load) of the propylene / α-olefin copolymer is 1 to 20 g / 10 minutes, preferably 2 to 20 g / 10 minutes. The measurement of MFR is performed according to JIS-K6921-2: 1997 appendix (230 degreeC, 21.18N load).

  The propylene / α-olefin copolymer used in the present invention has a melting peak temperature (Tm) measured by a differential scanning calorimeter (DSC) of 120 to 165 ° C, preferably 130 to 150 ° C. When Tm is less than the above range, the rigidity tends to be lowered, and it is difficult to obtain suitable blocking resistance, and when it exceeds the above range, flexibility tends to be impaired.

  The ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the propylene / α-olefin copolymer used in the present invention is 1.5 to 3.5, more preferably 1.8. ~ 3.3. Mw / Mn can be measured by gel permeation chromatography (GPC).

  In the propylene / α-olefin copolymer, it is preferable to add a nucleating agent such as a dibenzylidene sorbitol derivative, an organic phosphoric acid metal salt, an organic carboxylic acid metal salt, or a high-density polyethylene to the above-mentioned components. Transparency can be improved. The addition amount is 0.001 to 5% by weight, preferably about 0.01 to 3% by weight. High density polyethylene can simultaneously improve processing stability by addition.

  Conventionally, when a polypropylene is formed by a biaxial stretching film forming method, a technique for improving gloss by adding a nucleating agent is generally used, but originally, gloss is expressed in the biaxial stretching film forming process. Therefore, even if the nucleating agent was further added, the glossiness beyond that was only slight. On the other hand, glossiness can be remarkably improved by adding a nucleating agent to the propylene / α-olefin copolymer obtained by a single site catalyst. This is a molding method in which inflation molding is slow cooling due to cooling and solidification with air, and spherulites may grow and hinder the appearance of gloss. This is considered to be more remarkable with a propylene / α-olefin copolymer using a single site catalyst.

  The propylene / α-olefin copolymer of the present invention can be blended with other additional optional components as long as the effects of the present invention are not significantly impaired. Examples of such optional components include antioxidants, clarifying agents, lubricants, antiblocking agents, antistatic agents, antifogging agents, neutralizing agents, metal deactivators, and colorants used in ordinary polyolefin resin materials. And a fluorescent brightening agent.

  The additive is blended as needed at any stage of preparing the resin composition. For melt kneading, for example, each component in the form of powder, pellets, etc. is mixed with a uniaxial or biaxial extruder, Banbury mixer, kneader blender, Brabender plastograph, small batch mixer, continuous mixer, mixing roll, etc. Done using. The kneading temperature is generally 180 to 270 ° C.

  The method for producing the heat-adhesive film of the present invention is not particularly limited, but the heat-adhesive layer, the intermediate layer, and the base layer can be co-formed by inflation molding or T-die molding using a plurality of extruders and a co-extrusion multilayer die. A manufacturing method for forming a film with an extruded film is preferred.

As the inflation molding method in the present invention, a thermal adhesive layer, an intermediate layer, and a base layer are melted by a plurality of extruders with a co-extrusion multilayer annular die and extruded into a tube shape, and air supplied from a blower or the like is air-cooled ring After being cooled and solidified by spraying from a molten tube, it can be obtained by a method of folding with a pinch roll through a guide plate and taking it out with a take-up machine.

  Further, the thickness ratio is not particularly limited, but the thermal adhesive layer can be appropriately expressed as the thermal adhesive layer is thick to some extent, and the thicker base layer can fully express the function as a film. About 50/50 to 99/1 is preferable, about 60/40 to 97/3 is more preferable, and the balance of physical properties is particularly preferable if it is 70/30 to 95/5.

  In the case of providing an intermediate layer, a certain thickness is required to provide a function, and the layer ratio is preferably 5% or more, more preferably 10% or more, and more preferably 20% or more with respect to all layers. Is particularly preferred.

  As a molding machine, a cooling ring, a blower, a guide plate, a pinch roll, and a film take-up machine that can be used in this molding method, those generally used can be used.

  The conditions for molding the heat-adhesive film in the present invention are not particularly limited as long as the characteristics specified in the present invention are obtained, but the molding temperature is 170 to 250 ° C., preferably 170 to 200 ° C., and the molding speed is 10 to 300 m. / Min, preferably 50 to 200 m / min.

  Corona treatment can also be applied to the surface of the thermal adhesive layer to enhance the thermal adhesive function.

  As conditions for the corona treatment, the wetting tension according to JIS K 6768 is preferably 36 mN / m or more, more preferably 38 mN / m or more, and further preferably 40 mN / m or more.

  The heat-adhesive film of the present invention covers a part or all of the window hole of a paper packaging molded body and its peripheral paper portion from the inside of the packaging molded body, and also thermally bonds the thermal adhesive film. The layer side is used by being thermally bonded to the peripheral paper portion. There is no restriction | limiting in particular in the method of heat-bonding, A well-known method can be used.

  In terms of resource recycling, it is preferable that the heat-adhesive film and the paper can be easily separated after use of the packaging molded body.

  Conventionally, a method of cutting a cut portion including a resin film from an envelope body along a perforation provided in a paper portion has also been proposed (for example, Japanese Patent Application Laid-Open No. 2006-103797 and Japanese Patent Application Laid-Open No. 2008-56320). ). However, even if the paper is cut from the cut line as described above, the paper and the resin film remain bonded, and the paper and the resin film are not separated from each other, which is an insufficient method for completing resource recycling.

  The inventor has intensively studied a thermal adhesive film, paper, and thermal adhesive that have a certain strength and can be easily peeled off. And, if the components of the thermal adhesive layer are the above-mentioned (A) to (C), by applying the following device to the shape of the thermal adhesive part, it has a certain strength and can be easily peeled off. Found that it would be possible.

In FIG. 2, the example of formation of the heat bonding site | part was shown. In this way, it is preferable to form the thermal bonding portion A partially in a linear shape as shown in FIG. 2A, rather than thermally bonding the entire surface of the joint with paper. Furthermore, it is more preferable to form the thermal bonding portion B in a broken line shape as shown in FIG. 2B than the above linear shape because it can be easily separated at the time of separation after obtaining the adhesive strength between the paper and the film. . Furthermore, as shown in FIG. 2 (c), a method of forming the thermal bonding portion C in a dot shape is more preferable because it can be easily peeled off after obtaining a certain strength over a wide area.

  By forming the heat-bonded part as described above, a packaging molded body that can be easily separated from the paper after use and can be cleanly separated is provided.

  In such thermal bonding, heat sealing is performed using a surface-shaped seal bar having linear, broken line, or dot-like protrusions on the surface, and similarly, linear, broken line, or dot-like protrusions are provided on the surface. It can be performed by selecting a method of niping with a rubber roll facing each other using a hot roll.

  The temperature of the planar seal bar and the heat roll is not particularly limited as long as thermal adhesion is expressed, but if it is too low, thermal adhesion is not expressed, so 80 ° C. or higher is preferable, and more than 90 ° C. A temperature of 100 ° C. or higher is particularly preferable because sufficient adhesion can be expected. Moreover, since the film may be deformed or damaged when the temperature is too high, it is preferably 150 ° C. or lower, more preferably 140 ° C. or lower, and particularly preferably 130 ° C. or lower.

  Moreover, in the molded article for packaging, the Haze value (based on a general measurement in accordance with JIS K 7136) of the thermal adhesive film is preferably 20% or less, and more preferably 15% or less. . By satisfying this condition, most people can strongly feel the transparency with respect to the thermal adhesive film.

  As a use of the molded article for packaging of the present invention, a tissue box can be preferably exemplified in addition to an envelope with a window. In the conventional tissue box, since the film is adhered with an adhesive, the adhesive protrudes from the end of the film, and the protruded adhesive damages the tissue. In order to avoid this, a method is used in which the adhesive part is not formed to the end of the film. In this case, the film end is lifted from the inner surface of the box when the tissue is taken out, and the film is raised. The edge causes the problem of tissue damage. In order to alleviate this problem, a method of forming the film with a flexible material is used. However, the flexibility of the film leads to an increase in cost, and the shape of the flexible film is unstable. In addition, the tissue box is difficult to handle at the time of molding, resulting in a high rate of defective products. On the other hand, if the heat-adhesive film of the present invention is used, even if bonding is performed up to the end of the film, the solvent does not protrude from the end, so that the tissue is not damaged. The effect of adhering to the end of the film is also obtained in the case of an envelope with a window. That is, when the inclusion is taken in and out of the envelope, an effect of preventing the inclusion from being caught on the end of the film can be obtained.

  In the present invention, the coating of the window hole with the heat-adhesive film may cover a part of the window hole and its peripheral paper portion. An example of a molded article for packaging obtained by such coating is shown in FIG. It was shown in 3.

  In FIG. 3, two heat-adhesive films 2 and 2 cover the part of the window hole 30 and its peripheral paper portion, respectively, to form the packaging molded body 1.

The configuration as described above is particularly effective when, for example, the packaging molded body 1 is a tissue box. That is, in the conventional tissue box, the film covering the window hole is provided with a cut line, and the tissue is taken out through a gap generated by the cut line. There have been problems such as an increase in the number and generation of defective products due to positional deviation between the broken line portion and the window hole. On the other hand, with the configuration as described above, the tissue can be taken out through the gap formed between the two heat-adhesive films 2 and 2, so that the step of forming the cut line is unnecessary. In addition, productivity can be improved and a stable effect can be obtained.

  Moreover, when it is going to form the above structures by adhesion | attachment using the conventional adhesive agent, an adhesive agent protrudes between the two heat adhesive films 2 and 2, and the adhesive agent which protruded damages a tissue etc. However, as described above, if the heat-adhesive film of the present invention is used, even if the film is bonded to the end, the solvent does not protrude from the end. Yes, the adhesive sticks out between the two heat-adhesive films 2 and 2 and does not damage the tissue.

  EXAMPLES Hereinafter, the present invention will be specifically described according to examples, but the present invention is not limited to these examples. The resins and molding machines used in the examples are as follows.

<Used resin and molding machine>
(1) Resin base layer:
WFX6: propylene / α-olefin copolymer (unstretched) by a single site catalyst manufactured by Nippon Polypropylene, MFR = 2 g / 10 min, melting point = 125 ° C.
HE30: manufactured by Nippon Polyethylene Co., Ltd., MFR = 0.3 g / 10 min, density = 0.92 g / cm ³
-PB260: Polypropylene film (thickness 20 μm, width 840 mm) manufactured by Nimura Chemical Industry Co., Ltd. and biaxially stretched
-Teflex FT: manufactured by Teijin DuPont Films, Inc. Biaxially stretched polyethylene terephthalate (thickness 20 μm, width 840 mm)
Middle layer:
HE30: Use the same as shown in the above base layer.
Thermal adhesive layer:
KF260T: manufactured by Nippon Polyethylene Co., Ltd., ethylene / α-olefin copolymer polymerized using a single site catalyst, MFR = 2 g / 10 min, density = 0.903 g / cm ³
Novatec LV570: Ethylene / vinyl acetate copolymer (EVA) manufactured by Nippon Polyethylene Co., Ltd., MFR: 15 g / 10 min, vinyl acetate (VA) content: 20% by weight
NUC-6225: Nippon Unicar Co., Ltd. ethylene ethyl acrylate copolymer (EEA) MFR 5 g / 10 min, ethyl acrylate (EA) content: 13% by weight
-XM138: manufactured by Nippon Polyethylene Co., Ltd., linear low density ethylene

(2) Extruder Extruder: Sumiju Modern Machinery Co., Ltd. 3-type 3-layer coextrusion extruder Extruder diameter: φ65mm
Die diameter: 350mm
Extruder set temperature: 180 ° C
Die set temperature: 190 ℃

Example 1
A film was formed with the composition and layer ratio shown in Table 1. At that time, the extrusion speed was adjusted to 100 kg / h and the tube width was 800 mm, the surface of the heat bonding layer was subjected to corona treatment in-line, and the ear was cut off by the in-line slit to obtain a final film product having a width of 780 mm. A two-layer film was formed using a three-kind three-layer machine. The outer layer of the bubble was formed as KF260T (thermal adhesive layer), and the remaining two layers (base layer) were formed as the same HE30 (unstretched). Thereafter, it was slit to a width of 50 mm with an outline slit.

  A cardboard with a sheet window frame was prepared, the film was applied to the window, and the linear seal bar shown in FIG. 2A was pressed and fused to obtain a molded body.

<Evaluation>
The obtained molded body was evaluated on the following items.

1. Blocking resistance The blocking resistance at the time of thermal bonding between the molded article for packaging and the thermal adhesive film was evaluated according to the following criteria.
○: No blocking occurred, △: Blocking occurred slightly, ×: Blocking occurred

2. Solvent odor Immediately after the molded body for packaging and the heat-adhesive film were thermally bonded, the odor was confirmed according to the following criteria. The results are shown in Table 1.
○: No solvent odor, △: Slight solvent odor, ×: Solvent odor

3. Haze value The haze value of the film window in the obtained packaging molded body was measured based on general measurement according to JIS K7136. The results are shown in Table 1.

4). Perspective The obtained molded product for packaging is used on a monitor, paper with characters printed on it is sealed in the molded product for packaging, and the clarity of the characters is reduced through the window hole covered with film as follows. Evaluated by criteria. In the evaluation, samples were handed to 20 monitors, and the closest item was selected as sensitivity, and the number is shown in Table 1.
○: clear, △: slightly blurred, x: unclear

5). Peelability The film part was peeled off from the cardboard by hand, and the peelability was evaluated. In the evaluation, samples were handed to 20 monitors, and the closest item was selected as sensitivity, and the number is shown in Table 1.
A: Appropriate division was possible with almost no paper peeling, B: Slight paper peeling but almost good division, B: Paper peeling but division, x: Film was partially broken

  The above evaluation results are shown in Table 1.

  As can be seen from the evaluation results of peelability, the film and the cardboard could be divided without breaking the film. This is good, unlike the case where the film was broken in the comparative example in which the film and the cardboard were bonded using the adhesive described later. When adhesives are used, the adhesive must penetrate into the cardboard and become strongly bonded to the paper, whereas in heat fusion, only the film surface and the cardboard surface form the fusion point. This is considered to be because it worked well.

  14 out of 20 people peeled off the surface of the paper when it was divided and adhered to the film, but the amount of paper peeled off by 6 people was only slightly attached to the film. Unlike the comparative examples described later, there were six cases where the paper was slightly peeled off. This is probably because the fusion was formed only on the respective surfaces of the film and the cardboard.

(Example 2)
A molded body was obtained in the same manner as in Example 1 except that Novatec LV570 was used for the thermal adhesive layer.

  The obtained molded product was evaluated for the same items as in Example 1, and the results are shown in Table 1.

  As can be seen from the evaluation results of peelability, the film and the cardboard could be divided without breaking the film. In addition, 15 out of 20 people peeled off the surface of the paper when it was divided and adhered to the film, but the amount of paper removed by 5 people was only slightly attached to the film.

(Example 3)
A molded body was obtained in the same manner as in Example 1 except that NUC-6225 was used for the thermal adhesive layer.

  The obtained molded product was evaluated for the same items as in Example 1, and the results are shown in Table 1.

  As can be seen from the evaluation results of peelability, the film and the cardboard could be divided without breaking the film. In addition, 15 out of 20 people peeled off the surface of the paper when it was divided and adhered to the film, but the amount of paper removed by 5 people was only slightly attached to the film.

Example 4
As shown in the table, a molded body was obtained in the same manner as in Example 1 except that WFX6 (unstretched) was used for the base layer, an intermediate layer composed of HE30 was provided, and the layer ratio shown in Table 1 was used.

  The obtained molded product was evaluated for the same items as in Example 1, and the results are shown in Table 1.

  As can be seen from the evaluation results of peelability, the film and cardboard could be divided without breaking the film. In addition, 12 out of 20 people peeled off the surface of the paper when it was divided and adhered to the film, but the amount of paper removed by 8 people was only slightly attached to the film.

(Example 5)
A molded body was obtained in the same manner as in Example 4 except that the shape of the seal bar was changed to the broken line shown in FIG.

  The obtained molded product was evaluated for the same items as in Example 1, and the results are shown in Table 1.

  As can be seen from the evaluation results of peelability, the film and the cardboard could be divided without breaking the film. In addition, 9 out of 20 people had very few paper marks on the film surface, and they peeled off very well without peeling off the paper. Seven people peeled off the paper slightly, but were able to divide well. The four were able to split the paper and film, although they had peeled off the paper.

(Example 6)
A molded body was obtained in the same manner as in Examples 4 and 5 except that the shape of the seal bar was changed to the dot shape shown in FIG.

  The obtained molded product was evaluated for the same items as in Example 1, and the results are shown in Table 1.

As can be seen from the evaluation results of peelability, the film and the cardboard could be divided without breaking the film. In addition, 16 out of 20 people had only a slight trace of paper on the film surface, and they were peeled off very well without peeling off the paper. Seven people peeled off the paper slightly, but were able to divide well. Although the four peeled off the paper, the paper and film could be separated.

  It is considered that the establishment of the fracture interface between the film and the cardboard at the time of peeling only occurs at the fused portion by using the fusion point of heat fusion as a point.

(Comparative Example 1)
As shown in the table, a film was obtained in the same manner as in Example 1 except that only HE30 was used. The obtained film was adhered to cardboard using a solvent-type adhesive to obtain a molded body. The application shape of the adhesive was a linear shape shown in FIG.

  The obtained molded product was evaluated for the same items as in Example 1, and the results are shown in Table 1.

  As can be seen from the evaluation results of the peelability, the film was slightly broken, and eight cases where the film and the cardboard could not be separated well were generated. In the remaining 12 cases, the film and cardboard were separated, but all of them were peeled off, and there was no example where there was no paper peeling or slight paper peeling.

  This is presumably because the adhesive penetrates into the paper, and when it is peeled off, the portion of the thick paper where the adhesive penetrated is broken and peeled off.

(Comparative Example 2)
As shown in the table, a film was obtained in the same manner as in Comparative Example 1 except that a hot melt type adhesive was used, and adhered to cardboard to obtain a molded body.

  The obtained molded product was evaluated for the same items as in Example 1, and the results are shown in Table 1.

  As can be seen from the evaluation results of the peelability, the film was broken a little, and five cases where the film and the cardboard could not be separated well were generated. In the remaining 15 cases, the separation of the film and the cardboard was realized, but all the papers were peeled off, and there was no example where there was no paper peeling or slight paper peeling.

(Comparative Example 3)
As a base material to be a base layer, a biaxially stretched polypropylene film (PB260) is used, and a thermal adhesive layer is made of linear low density ethylene (XM138). From a T die attached to an extruder, a resin temperature of 240 ° C. , Effective die width 1100 mm, cooling roll surface specification Mirror-like, wall thickness was 15 μm, and melt extruded.

  Next, the base layer is fed out from the feeding part of the base material of the extrusion laminating apparatus, an anchor coating agent is applied to one side, and after the drying, ozone treatment is performed between the coated surface and the heat-bonded layer melt-extruded from the T-die into a film Then, it was pressure-bonded and laminated with a cooling roll and a compressed rubber roll, the ear was cut off with an in-line slit to a width of 800 mm, and the surface of the resin layer of the laminated film was subjected to corona discharge treatment to obtain a laminated film.

  The winding form of the laminating machine, which has a total thickness of about 35μm, is not aligned well, and the ear height and the ear breakage during handling will occur. Thus, a laminated film having a width of 780 mm was obtained.

  After that, an attempt was made to produce a slit product having a width of 50 mm with an outline slit, but the blocking of the raw fabric was strong and tearing occurred at the feed portion of the original fabric, so that a slit product could not be obtained.

  This shows that blocking is induced by using a stretched film for the base layer.

(Comparative Example 4)
A laminated film was obtained in the same manner as in Comparative Example 3 except that the base layer was made of polyethylene terephthalate (Teflex FT) obtained by biaxial stretching.

  The winding form of the laminating machine, which has a total thickness of about 35μm, is not aligned well, and the ear height and the ear breakage during handling will occur. Thus, a laminated film having a width of 780 mm was obtained.

  After that, an attempt was made to produce a slit product having a width of 50 mm with an outline slit, but the blocking of the raw fabric was strong and tearing occurred at the feed portion of the original fabric, so that a slit product could not be obtained.

(Comparative Example 5)
A laminated film was obtained in the same manner as in Comparative Example 3 except that the cooling roll surface specification of the extrusion laminate was changed to a DUC matte tone.

  The winding form of the laminating machine, which has a total thickness of about 35μm, is not aligned well, and the ear height and the ear breakage during handling will occur. Therefore, a secondary slit is applied with a slitter to cut off the end. Thus, a laminated film product having a width of 780 mm was obtained.

  Thereafter, a slit product having a width of 50 mm was obtained with an outline slit. However, unlike Comparative Example 3, blocking was alleviated and the outline slit was successfully formed.

  A cardboard with a sheet window frame was prepared, the obtained film was applied to the window, and the linear seal bar shown in FIG. 2A was pressed and fused to obtain a molded body.

  The obtained molded product was evaluated for the same items as in Example 1, and the results are shown in Table 1.

  Blocking was alleviated by using a matte (embossed) surface, but the film had a translucent film with a Haze value of 80%.

1: Molded body for packaging 2: Thermal adhesive film 21: Thermal adhesive layer 22: Intermediate layer 23: Base layer 3: Paper 30: Window hole 31: Peripheral paper part of window hole

Claims (4)

In a paper envelope-shaped or box-shaped packaging molded body having a window hole and covering the window hole with a resin film,
A part or all of the window hole and its peripheral paper part are covered from the inside of the molded article for packaging by a heat-adhesive film formed by laminating a heat-adhesive layer as a surface layer and an unstretched polyolefin layer as a base layer. And thermally bonding the thermal adhesive layer side of the thermal adhesive film to the peripheral paper part,
The molded article for packaging, wherein the thermal adhesive layer is made of at least one copolymer selected from the following (A) to (C).
(A) Ethylene / α-olefin copolymer polymerized using a single site catalyst (B) Ethylene / vinyl acetate copolymer (C) Ethylene / (meth) acrylic acid ester copolymer   The packaging material according to claim 1, further comprising an intermediate layer made of polyolefin between the thermal adhesive layer and the unstretched polyolefin layer, wherein the melting point of the unstretched polyolefin layer is higher than that of the intermediate layer. Molded body.   The molded article for packaging according to claim 1 or 2, wherein the heat adhesive film has a Haze value of 20% or less.   The molded body for packaging according to any one of claims 1 to 3, wherein the thermal bonding portion of the peripheral paper portion is formed in a broken line shape or a dot shape.

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