JP2002011832A - Close contact sealable lap film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lap film for a household for allowing excellent close contact sealability and drawing easiness to be compatible and further having good transparency or the like. SOLUTION: A close contact sealable lap film comprises a specific pressure sensitive adhesive layer of a marine island structure having a partly high stickiness, a specific protrusion part in which a mean height of a ruggedness and a mean interval are larger than a thickness of the adhesive layer and smaller than a thickness of a base material layer on an opposite side surface of the adhesive layer, and further the base material layer having a fine valley part of the shorter mean interval than a wavelength of a visible light on an oblique surface of the protrusion part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wrap film used for simple wrapping of foods and the like, which is preferably used as a wrap film for packaging, especially for household use, although its use is not particularly limited. More specifically, a wrap for a house hold, which has a sufficient sealing property to prevent the contents (liquid food) from spilling into a container containing the liquid food, has improved drawability, and is also excellent in transparency and the like. About the film.

[0002]

2. Description of the Related Art Conventionally, a wrap film for a house hold has been used to overlap foods placed in a container mainly for preservability of foods in a refrigerator or a freezer or for heating in a microwave oven. For this reason, household wrap film has not only transparency, but also an appropriate elastic modulus during packaging, storage and heating, and no perforation during heating, large deformation, fusion to a container, deformation of the container itself, etc. There is a demand for stability and proper adhesion between the wraps and the container from low to high temperatures. Currently, commercially available wrap films for household use include stretch films mainly composed of the most convenient polyvinylidene chloride-based resin, and other polyethylene-based resins and plasticized polyvinyl chloride-based plastics, which are significantly inferior in wrap suitability described later. Examples of the film include a resin and a film mainly containing poly-4-methylpentene-1 resin. However, the household has a high degree of close-adhesiveness that the content (liquid food) does not spill into the container containing the liquid food, and has good drawability and good transparency, which are contradictory characteristics. Wrap film has never been before. Here, the adhesive seal means the adhesiveness of the food container and the wrap film,
The pull-out property means the releasability between the wrap films when the wound wrap film in the decorative box is pulled out of the box.

[0003]

Generally, a wrap film is placed in a decorative box in a state of being wound around a paper tube (this state is called a rolled wrap film), and a container containing liquid food or the like is stored in a refrigerator or the like. While a high degree of tight sealing property is required so that the liquid of the contents does not spill out of the container when carrying in and out from the container, the tightness of the unwrapped wrap films is high when used by consumers. The drawability of the film decreases, and when the consumer who purchases the film tries to pull out the wrap film in the kitchen or the like, the film may be broken. In the present invention, it is an object of the present invention to provide a wrap film for a house hold which solves such a problem, has a high degree of close sealing property, is excellent in drawability, and further has good wrap suitability such as transparency. Aim.

[0004]

Means for Solving the Problems The inventors of the present invention have made intensive studies from the viewpoints of adhesion and sealing properties, drawability and transparency, and as a result, have found that a wrap film having a base material and an adhesive layer on the base material. In the ridge, the average height is smaller than the thickness of the pressure-sensitive adhesive layer and smaller than the thickness of the base material on the surface of the base material opposite to the pressure-sensitive adhesive layer, and further, the average distance shorter than the visible light wavelength on the ridge slope. It has been found that a wrap film characterized by having a fine valley portion and having a high-adhesion portion and a low-adhesion portion mixed on the surface of the pressure-sensitive adhesive layer is the most suitable. That is, the present invention includes the following three combinations.

[1] The wrap film material of the present invention has a laminated structure having a substrate layer and an adhesive layer on the substrate.
The height of the raised portion defined by the ten-point average roughness (R _Z ) measured at a cutoff value of 250 μm according to JIS B0601 is larger than the thickness of the pressure-sensitive adhesive layer, and A ridge smaller than the thickness, preferably
The projection has a conical mountain-shaped ridge. [2] Furthermore, JIS B0 is provided on the inclined side surface of the raised portion.
A fine valley having an average interval (S _m ) of 50 nm or more and less than 400 nm measured at a cutoff value of 4 μm in accordance with 601 is provided. [3] On the surface of the pressure-sensitive adhesive layer, the 90-degree peel strength measured according to JIS Z 0237 is 300 to 60.
0g / 25mm width high adhesion (adhesive) part and 1 to 15g / 25
It has a sea-island structure in which low-adhesion (property) portions having a width of mm are mixed, and preferably, the high-adhesion portions are connected and the low-adhesion portions are independently dispersed.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The contents of the present invention will be described below. The most different point of the present invention from the prior art is that the surface of the base material layer on the opposite surface side of the pressure-sensitive adhesive layer has a raised portion having a specific uneven height,
In addition, a specific spatial arrangement in which a high-adhesion part and a low-adhesion part are mixed on the surface of the pressure-sensitive adhesive layer is provided.

The role of the constituent element of the present invention, which is different from the above prior art, is that it has a drawability (drawing force: 80 g / 300 mm width or less) that does not block at the time of drawing in the form of a wound wrap film. Consumers have a high degree of tight sealing properties so that liquid does not spill out of the container during use, that is, properly derive both contradictory properties of tight sealing properties and drawability, and furthermore, wrap film It is also about solving transparency. The substrate used for the wrap film of the present invention is not particularly limited as long as it is used for food packaging. For example, polyethylene-based resins (HDPE, LLD)
Such as PE), polypropylene resin (PP), polybutene-1 resin (PB), polyolefin resin (PO) including poly-4-methylpentene-1 resin, or ethylene-vinyl acetate copolymer resin (EVA), ethene-methyl methacrylate copolymer resin (EMA
Etc.), ethylene-vinyl alcohol copolymer resin (E
Aromatics including modified polyolefin-based resins (VOH, etc.) (modified POs), polyethylene terephthalate-based (modified) resins (PET, etc.), and polybutylene terephthalate-based (modified) resins (PBT, etc.) Polyester resin (PEST) containing some components or aliphatic components such as polylactic acid resin and polyglycolic acid resin, polyvinylidene chloride resin (PVD)
C), chlorine resins such as polyvinyl chloride resin (PVC), α-olefin-carbon monoxide copolymer resin (including hydrogenated resin), α-olefin (ethylene, etc.)-Styrene copolymer resin (including The same hydrogenated resin), an ethylene-cyclic hydrocarbon-based compound copolymer resin (containing the same hydrogenated resin), a polyamide resin (Ny), a caprolactone-based resin, and the like. And known additives such as antioxidants, light stabilizers, antistatic agents, antifogging agents, coloring agents, lubricants and the like. Among them, polyethylene resins (HDPE, LLDPE
Etc.), a polypropylene-based resin (PP), a polyamide-based resin (Ny) and the like are preferable, and a polyester-based resin is more preferable in terms of heat resistance and transparency. In addition, the thickness (B) of the substrate is preferably about 5 to 30 μm.

The ridge structured on the surface of the base material according to the present invention refers to a portion that appears in a convex shape on the surface of the base material. The shape of the ridge may be, for example, a conical shape, a circular shape or a triangular shape. Shapes such as squares, grains, and the like, random shapes, grid shapes, line shapes, or convex portions having a combined form thereof can be given,
There is no particular limitation. Preferably, a conical grid pattern is used.

The raised portion is mechanically stamped / rolled using a female mold having a desired surface shape (roll or flat plate) with an uneven surface, or formed by injection / melt casting or the like, or The film is etched by a lithography method and is subjected to unevenness processing on the film surface. As a specific example of the processing method, for example, a Liga technology (X-ray Lithography), which is a processing method using X-rays for photolithography for producing microparts using a very small mold made of metal or ceramic developed in Germany, is used.
Galvanik (= Electroforming)
There is a method of subjecting a film surface to a desired unevenness by an embossing method or the like by using a female mold having an uneven surface manufactured by Ahformung (abbreviation of Modeling) with an accuracy of 50 to 100 nm. Also, the morphological measurement of this raised portion is performed by a surface shape observation device (SA manufactured by Meishin Koki Co., Ltd.).
S2100) or a scanning probe microscope three-dimensional surface observation device (SPM9500J manufactured by Shimadzu Corporation) or the like.
According to SB0601, the ten-point average roughness (R _Z ) of the raised portion, the average interval of unevenness (S _M ), the maximum height (R _y ), and the adhesive from the peak on the peak line of the maximum height (R _y ) volume and Sokodan area of the raised portion summit portions divided by layer thickness of (D), average irregularity interval fine valleys (S _m) the surface irregularities (surface roughness, unevenness side area, etc.), such as to measure the it can.

[0010] The wrap film of the present invention is JIS B0
The height of the raised portion defined by the evaluation length and the ten-point average roughness (R _Z ) measured at a cut-off value of 250 μm according to 601 is larger than the thickness (D) of the pressure-sensitive adhesive layer described below, and the base material thickness (B) ) Less than. Further, the average distance (S _M ) between the protrusions and depressions measured at an evaluation length and a cutoff value of 250 μm according to JIS B0601 may be about 5 to 150 μm. JIS B0601 is provided on the inclined side surface of the raised portion.
Average spacing measured at a cutoff value of 4 μm (S
_m ) preferably has a fine valley portion of 50 nm or more and less than 400 nm. In addition, the sum of the side areas of the ridge peaks calculated from the volume and the bottom cross-sectional area of the ridge peaks divided by the adhesive layer thickness (D) from the peaks on the peak line of the maximum height (R _y ) using a cone approximation The area ratio to the evaluation plane (substrate projection plane) is preferably 5% or more and 65% or less.

The pressure-sensitive adhesive layer of the present invention has a JI
The sea-island structure in which a 90-degree peeling adhesive force measured according to SZ0237 has a high-adhesion (adhesion) portion of 300 to 600 g / 25 mm width and a low-adhesion (adhesion) portion of 1 to 15 g / 25 mm width is mixed. I have. It is extruded or coated and laminated on the base material layer, and includes the following configurations (1) to (3).

(1) On the outer surface of the highly adhesive pressure-sensitive adhesive layer,
A low-viscosity through-hole substrate thinner than the pressure-sensitive adhesive layer thickness, for example,
This is a configuration in which porous layers such as nonwoven fabric, paper, woven fabric, porous plastic films, and plastic films that are perforated by light, heat, or mechanically are laminated and pressed to be integrated. In this configuration, a region (island) where the adhesive is dispersed and surfaced independently becomes a high adhesive portion due to the adhesive oozing out from the through-hole portion, and a region where the continuous non-through hole (sea) is low. It has a sea-island structure that becomes an adhesive part. (2) A structure in which a low-adhesive filler is mixed in a high-adhesive pressure-sensitive adhesive layer. This configuration has a sea-island structure in which the region of the low-adhesion portion is dispersed in the form of islands by further externalizing the filler partially from the surface of the highly-adhesive pressure-sensitive adhesive.
In addition, the filler referred to here is a solid having an arbitrary shape such as a fibrous shape or a spherical shape which is selected within a range for achieving low tackiness by partially surfaced on the surface of the pressure sensitive adhesive, for example, glass beads. , Spherical polymers, microcapsules, powders such as pigments, and short fibers such as pulp. (3) The pressure-sensitive adhesive layer has a structure in which a heat-sensitive pressure-sensitive adhesive exhibiting delayed tack performance is partially heat-activated. This configuration applies the property that the heat or light energy is partially applied to the surface of the heat-sensitive adhesive layer so that the heat-sensitive adhesive layer becomes highly tacky. This is a configuration in which the area of the adhesive portion is arbitrarily formed. Preferably, on the surface of the pressure-sensitive adhesive layer, a sea-island structure in which high pressure-sensitive portions are continuously connected (sea) and low pressure-sensitive portions are independently dispersed (islands).

The above-mentioned "sea-island structure" is not limited to a structure in which the sea (continuous layer) is completely continuous and all of the islands (discontinuous layers) are independently dispersed in the sea. It also includes a state where the island is partially interrupted and a state where some of the islands are fused with each other. The low adhesive area ratio on the surface of the pressure-sensitive adhesive layer is determined by measuring the cross-sectional area of the filler or the perforated portion on the outer surface with respect to the unit evaluation plane (projection plane of the pressure-sensitive adhesive layer) using a surface shape observation device or the like, It can be obtained from the processing area or the like in which the processing with the energy is performed.

The pressure-sensitive adhesive (p) used in the pressure-sensitive adhesive layer of the present invention
less-sensitive adhesiv
e) generally means "without the need for water, solvent, heat, etc., it can be applied to other surfaces under very weak pressure (eg, 5 g / cm ² or less) such as the weight of an adhesive as well as light finger pressure. It can be adhered, and if it is peeled off again, it can be easily peeled off without contaminating the adherend ", rubber-based adhesive, acrylic-based adhesive, vinyl ether-based adhesive, silicon-based adhesive , And a resin composition selected from at least one of heat-sensitive adhesives having delayed tack performance, etc., and known additives such as antioxidants, light stabilizers, antistatic agents, Contains fogging agents, coloring agents and the like.

The rubber-based pressure-sensitive adhesive is a natural rubber containing cis-1,4-polyisoprene as a main component, a synthetic rubber containing styrene / butadiene rubber (SBR), polyisobutylene, butyl rubber or the like as a main component, or styrene. ·butadiene·
Adhesive elastomers selected from styrene copolymer rubber (SBS) and at least one block rubber such as styrene-isoprene-styrene copolymer rubber (SIS) as a main component. About 1
Up to 10,000 amorphous oligomers (dimeric or higher molecular weight polymer) thermoplastic resins such as rosin-based resin, terpene-based resin, petroleum resin, chroman-indene resin, etc. Things.

Acrylic pressure-sensitive adhesives include a main monomer having tackiness typically represented by a homopolymer having a low Tg, such as alkyl acrylate, a lower alkyl acrylate, an alkyl methacrylate, vinyl acetate, and styrene. , Comonomers that can be copolymerized with main monomers such as acrylonitrile and give cohesiveness to increase Tg, carboxyl-containing monomers such as acrylic acid and methacrylic acid (such as acrylate), and tackiness such as hydroxyl group, epoxy group and amino group In some cases, the tackifier, softener, and the like are blended with a tacky reaction product of a functional group-containing monomer that serves as a crosslinking point.

The vinyl ether-based pressure-sensitive adhesive is a homopolymer such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether or a copolymer with acrylate (adhesive elastomer). It was done. The silicone-based pressure-sensitive adhesive is a polymer (or pressure-sensitive elastomer) having a residual silanol group (SiOH) at the terminal of a polymer chain represented by high-molecular-weight polydimethylsiloxane or polydimethyldiphenylsiloxane, and the above-mentioned tackifier and softener. Etc. are blended.

The heat-sensitive adhesive exhibiting delayed tack performance is non-adhesive (or low-adhesive) at room temperature, but develops adhesiveness by heating, and then exhibits long-term adhesiveness even after removing the heating source. It lasts, and preferably includes the following configurations (a) to (c). (A) a thermoplastic substance (adhesive elastomer) as a main component that imparts adhesive strength, and a heat-fusible substance (solid plasticizer, (A microcapsule containing a plasticizer) and a tackifier for further improving the tackiness.

For example, a thermoplastic material typified by a natural rubber obtained by graft copolymerization of a vinyl monomer with a solid plasticizer such as dicyclohexyl phthalate as a thermofusible material;
There is one containing a tackifier such as rosin ether.
(See JP-A-10-338865) (b) Prior to the heat treatment, the non-adhesive component has a sea-island (continuous layer) and the adhesive component is an island (continuous layer). The pressure-sensitive adhesive composition is a pressure-sensitive adhesive composition in which islands are reversed to change into a sea-island structure in which non-adhesive components are islands and adhesive components are seas. For example, as a non-adhesive component, a water-soluble neutralized aqueous solution of methyl methacrylate / styrene / acrylic acid copolymer, which is a substantially non-crosslinkable resin whose acid value is neutralized with a base, and Tg as an adhesive component, 20 ℃ or less (meta)
There is a mixture of a mixture of an emulsion polymer mainly composed of an acrylate ester and solid particles at room temperature. (Japanese Patent Laid-Open No. 11-
No. 228927)

(C) The entire pressure-sensitive adhesive layer is made to have low tackiness by elongating and rapidly cooling the pressure-sensitive adhesive layer (the entire base material including the pressure-sensitive adhesive layer) to induce oriented crystallization of the pressure-sensitive adhesive elastomer of the pressure-sensitive adhesive layer. . When this is heated, the crystal of the elastomer is melted and the orientation is relaxed, so that only the heated portion is made to exhibit tackiness. The thickness (D) of the pressure-sensitive adhesive layer is 0.5 to 20 μm.
It is good to be about.

The wrap film of the present invention preferably has a total thickness of about 5 to 50 μm. The relationship between the configuration and the effect of the wrap film used for the wrap film material of the present invention will be described with reference to FIGS. FIG. 1 and FIG. 2 show the characteristics of the quantitative effect of the close-adhesive sealing property and the draw-out property in the combined system of the high and low pressure-sensitive adhesive structure on the pressure-sensitive adhesive layer surface and the raised structure on the substrate layer surface in the wrap film of the present invention. FIG. 3 is an explanatory view showing the characteristics of the quantitative effect of the fine ridges on the surface of the base material layer on the transparency of the wrap film of the present invention on the transparency, and is an experimental result of Examples and Comparative Examples. It corresponds to.

First, the relationship between the tight sealing property / drawing property of the wrap film material of the present invention and the surface structures of the pressure-sensitive adhesive layer and the base material layer will be described with reference to FIGS. Figure 1
Is the drawability (peak value: unit g / 300) of the wound wrap film with respect to the pressure-sensitive adhesive layer constitution having a specific adhesive force.
mm width) and the side area ratio [%: calculated value of the evaluation plane (unit base material projection plane)] of the peak area of the ridge on the surface of the base material layer which can come into contact with the pressure-sensitive adhesive layer. It is an explanatory view, and the mark “積 層” is obtained by laminating and pressing a low-adhesion perforated plastic film (about 1 μm thick PET film) thinner than the adhesive layer thickness (about 2 μm) on the outer surface of the high-adhesion adhesive layer. Area (island) where the pressure-sensitive adhesive has been surfaced from the through-hole as a whole
In the case of a wrap film having a sea-island structure pressure-sensitive adhesive layer in which is a high-adhesion part (approximately 300 g / 25 mm width) and a non-perforated area (sea) is a low-adhesion part (approximately 2 g / 25 mm width), Is a low-adhesion part (approximately 2 g / 25 mm width) by mixing a low-adhesion filler into a high-adhesion adhesive and partially exposing the filler to the surface of the high-adhesion part (approximately 300 g / 25 mm width). ) Is a sea-island structure adhesive layer (approximately 2 μm) in which islands are scattered, the mark ○ indicates a highly adhesive part obtained by partially thermally activating a heat-sensitive adhesive exhibiting delayed tack performance as an adhesive. (Approximately 300 g / 25 mm wide sea) and a low-adhesion portion that is not heat-activated (approximately 10 g / 2
(5mm wide island) low-adhesion part that does not thermally activate 60 rounds
Adhesive layer with sea-island structure arranged in a staggered pattern (approx.
m) In the case of the constitution, the mark “◇” indicates a medium adhesiveness (about 1
In the case of a pressure-sensitive adhesive layer (approximately 2 μm) having a thickness of about 00 g / 25 mm, the adhesive strength of the layer configuration in a PET film having a thickness of about 15 μm in the substrate layer is shown. Also, in FIG. 1, when the opening of a cylindrical glass cup having a diameter of 55 mm filled with 100 g of water and tightly sealed was tilted 180 ° for 10 seconds (once) using each wrap film, , And those in which the wrap film was excessively stretched or torn when the wrap film was peeled off from the cup were indicated by blacking out the marks.

From the results shown in FIG. 1, the sea-island structure of the high-adhesion portion and the low-adhesion portion of the present invention was compared with that of the adhesive layer surface having a medium adhesiveness of about 100 g / 25 mm width. Since there is a suitable range in which water does not leak and the substrate is not broken, it can be seen that the specific structure of the surface of the pressure-sensitive adhesive layer can suitably exhibit the close-adhesive sealing property beyond the numerical value of the pressure-sensitive adhesive strength. That is, the range of the adhesive strength averaged per wrap film width is 15 g / 25 mm width or more and 250 g / 25 m or more.
In the wrap film material of the present invention having a width of not more than m, the high adhesive portion having an adhesive strength of 300 g / 25 mm or more has a thickness of 15 g / 2.
It is only when the low-adhesion portion having a width of less than 5 mm and the sea-island structure having a high-adhesion portion area ratio of 25% or more and 60% or less on the surface of the pressure-sensitive adhesive layer can exhibit the tight sealing property in which water does not leak. In particular, the sea-island structure in which the high-adhesion portions are continuously connected to form a sea, and more preferably, the low-adhesion portions are arranged in a staggered 60-degree staggered shape in a round shape, is that even if the cup is tilted 180 degrees several times, A high degree of tight sealing property without leakage can be exhibited.

FIG. 2 shows the adhesion and sealing properties of the wrap film (peak value of adhesive strength: unit g / 25 mm width) and the ratio of the area of the high adhesive portion on the surface of the adhesive layer [to the evaluation plane (unit adhesive layer projection plane): FIG. 3 is an explanatory view showing the characteristics of the quantitative effect of the present invention, and a low-adhesion perforated plastic film thinner than the adhesive layer thickness (about 2 μm) on the outer surface of the highly-adhesive adhesive layer of the present invention. (About 1 μm thick PET film) is laminated and pressed and integrated to form a sea-island structure in which the area (island) where the adhesive is surfaced from the through-hole is a high-adhesion area and the area (sea) that is not through-hole is a low-adhesion area. In the pressure-sensitive adhesive layer configuration,
The mark indicates the adhesive strength of 15 g / 25 mm width corresponding to the lower limit of the high-adhesion sealing property such that the liquid does not spill out of the container during use by the consumer. The mark indicates the wrap film base of the present invention at the time of peeling. Adhesive strength of 250g corresponding to the upper limit value of the adhesive seal so that the material layer does not stretch or break excessively
/ PE with a thickness of about 20 μm when the substrate layer is 25 mm wide
It shows the drawability of a wound wrap film having a layer configuration in a T film. Further, as the pressure-sensitive adhesive of the present invention, a high pressure-sensitive adhesive part (sea) partially heat-activated from a heat-sensitive pressure-sensitive adhesive exhibiting delayed tack performance and a low pressure-sensitive adhesive part (island) not heat-activated can be optionally selected. In the formed sea-island structure pressure-sensitive adhesive layer (approximately 2 μm), the mark ○ indicates the adhesive force corresponding to the lower limit of the high level of tight sealing property so that the liquid does not spill out of the container during use. 15g / 25
In the case of a width of mm, the square mark indicates a base value in the case of an adhesive strength of 250 g / 25 mm width, which corresponds to the upper limit value of the adhesion and sealing properties so that the wrap film base layer of the present invention does not excessively stretch or break when peeled. It shows the drawability of a wound wrap film having a layer configuration in a PET film having a thickness of about 20 μm. Of which, 80g / 300mm withdrawal force
Those having practical problems exceeding the width are indicated by blacking out the marks.

From the results shown in FIG. 2, it can be seen that the adhesive layer having a sea-island structure in which the highly adhesive portion is sea tends to have a large drawing force even when the adhesive strength is the same level. It can be seen that the sea-island structure of the adhesive portion / low adhesive portion is related to the drawability. Also, a pull-out force 80 that does not block at the time of pulling out in the form of a wound wrap film.
g / 300 mm width or less, the side area ratio of the peak portion of the ridge on the surface of the base material layer that can come into contact with the pressure-sensitive adhesive layer having a width of not more than g / 300 mm [calculated value of the evaluation plane (unit base material projection plane): unit%] The appropriate range differs depending on the sea-island structure on the surface, but it is understood that 65% or less, more preferably 10% or less is good,
Since the side area ratio of the minimum ridge top that can be actually processed is about 5%, the range of 5% to 65%, more preferably 5% to 10% is appropriate for the ridge top. It can be seen that this is the side area ratio.

Next, the relationship between the transparency of the wrap film material of the present invention and the fine valleys processed on the uneven surface of the substrate will be described with reference to FIG. In FIG. 3, as the wrap film material of the present invention, about 2 μm of a heat-sensitive adhesive exhibiting a delayed tack performance obtained by partially thermally activating the PET film in the base layer and about 2 μm (total thickness of about 20 μm) )), The ten-point average height (R _Z ) and the average spacing between irregularities (S _M ) of the outer surface of the base material layer
Wrap film material for a modification (unit: nm S _m) but protuberance sloped surface of about 3μm ten-point average depth is processed in (side) (R _z) of about 100nm average spacing of fine valleys Haze (Haz) which is a transparency index of (all layers)
e: unit%), and those having inferior transparency with a haze of 1% or more were also indicated by blacking out the marks.

From the results shown in FIG. 3, the average interval (S
Those having _m ) of not less than 50 nm and less than 400 nm have a haze of less than 1%, indicating good transparency. That is, the present invention, by selecting the surface of the pressure-sensitive adhesive layer so as to have a sea-island structure in which the high-adhesion part and the low-adhesion part are mixed so as to have a specific high-adhesion part ratio, the base material does not break without water leakage. By having a structure having a specific ridge on the surface of the base material layer on the opposite side of the pressure-sensitive adhesive layer, the opposite properties of good adhesion and excellent drawability are compatible, and It has been found that the structure having fine valleys having an average interval smaller than the wavelength of visible light (about 400 to 800 nm) on the side surface of the ridge on the surface of the base material layer improves the transparency, thereby achieving the present invention. That's what happened.

Next, the evaluation method used in the present invention will be described below. <Adhesive Sealing Property> This method evaluates the adhesion between a wrap film and glass, assuming that food is wrapped in a wrap film in a kitchen at normal temperature (23 ° C., 65% relative humidity). << Adhesive force >> The test method is based on JIS Z 0237.
25 stored at room temperature (23 ° C., relative humidity 65%) for 7 days
A sample of a wrap film sampled in mm width
The test piece was lightly stuck on a clean and smooth glass plate, pressure-bonded three times with a 2000 g pressure roller from the top of the test piece, allowed to stand for 30 minutes, peeled off at 90 degrees, and measured for adhesive strength. (Unit g / 25mm width)

<< Liquid sealability >> The test method is 200 mm
A lap film test piece sampled in a 200 mm square was placed so as to cover the opening of a cylindrical glass cup having an opening diameter of 55 mm and a height of 100 mm filled with 100 g of water. The outer surface in the vicinity of the part is pressed down by hand and brought into close contact with it, 180 ° for 10 seconds (once) so that the glass cup opening is on the lower side
After tilting, observe the condition when the glass cup is returned to the original state so that the opening is up, and when the test piece is peeled off from the glass cup by hand (at the time of peeling), observe the state of the test piece. The following (1) was evaluated as good, and (2) and (3) were evaluated as poor. (1) The test piece did not come off the glass cup and no water leaked. The wrap film does not break when peeled. (2) The test piece does not peel off from the glass cup, but a little water leaks. Or, at the time of peeling, the wrap film is excessively stretched or broken. (3) The test piece comes off the glass cup.

<Pullability> A bearing-type free roll composed of a driving part (1 in FIG. 4) having a length of about 31 cm and a diameter of about 3.6 cm and a fulcrum shaft (2 in FIG. 4) having a length of 33 cm is wound. The wound wrap film is inserted into the paper tube (3 in FIG. 4) so that the center in the width direction of the wound wrap film and the center in the length direction of the free roll drive unit are aligned to integrate them. The free roll integrated with the wound wrap film is transferred to a universal tensile and compression tester TC, manufactured by Shinko Tsushin Kogyo Co., Ltd.
Wrap film wound in the vertical direction at the center of the hanger (4 in FIG. 4), with the hanger (4 in FIG. 4) suspended on the load cell side above the M-200 and its fulcrum axis (2 in FIG. 4) in parallel The fulcrum shaft (2 in FIG. 4) is fixed to a bearing (6 in FIG. 4) installed on the pull-down movable body (5 in FIG. 4) below the tester so that the center in the width direction of the tester is located. Furthermore, a wrap film integrated with the free roll (FIG. 4)
7) is peeled off and fixed to a hanger (4 in FIG. 4) suspended on the load cell side above the tester with a double-sided tape without wrinkles. Then, in a constant temperature room at 23 ° C,
The lowering movable body (5 in FIG. 4) at the lower part of the testing machine is 1000 m
wrap film (7 in Fig. 4)
Is vertically peeled off from the paper tube (3 in FIG. 4).

In this case, the peak value of the force required to peel the wrap film (7 in FIG. 4) from the paper tube (3 in FIG. 4) is used as a measured value of the pull-out property (unit: g / 3).
0 cm width), the following (1) to (2) are good, and (3) to
(4) was evaluated as defective. (1) a peak value of 65 or less = having satisfactory drawability;
Excellent level (2) Peak value 65-80 or less = good drawability, good practical level (3) Peak value 80-100 or less = poor drawability,
There is a problem in practical use. (4) Peak value exceeding 100 = Pullability is very poor, and practical use is impossible.

<Transparency> According to ASTM-D-1003, the haze (H
aze: unit%), and averaged over 6 points (rounded)
Good film transparency (1)-(2),
(3) was evaluated as defective. (1) Haze 0.3 or less = very good transparency (2) Haze 0.4 to 0.9 = good transparency (3) 1.0 or more = poor transparency

[0033]

According to the present invention, by satisfying the above-described structure, the contents (liquid food) can be stored in a container containing the liquid food.
It is possible to obtain a wrap film for a house hold used for simple packaging of foods and the like, which sufficiently retains close-adhesive sealability with little spilling, has improved drawability, and is excellent in transparency and the like. Therefore, the present invention is extremely significant in practical use.

[Brief description of the drawings]

FIG. 1 is a first experimental diagram for explaining the technical contents (adhesion sealability) of the present invention.

FIG. 2 is a second experimental diagram for explaining the technical contents (pullability) of the present invention.

FIG. 3 is a third experimental diagram illustrating the technical content (transparency) of the present invention.

FIG. 4 is a schematic front view showing a method for measuring the pull-out property.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Free-roll drive part 2 Free-roll fulcrum shaft 3 Paper core 4 Hanger 5 Pull-down movable body 6 Bearing 7 Wrap film

Continued on the front page F-term (reference) 3E086 AA02 AB02 AD13 BA04 BA15 BA24 BA44 BB22 BB57 CA01 DA01 4F071 AA15 AA20 AA46 AA54 AF30 AF58 AH04 BC01 BC08 BC14 BC15 BC16 4F100 AK25G AK42 AR00B AT00A BA02 BA23 BA25 BA13 GB14 GB14

Claims (10)

[Claims] 1. A wrap film having a substrate having a raised portion on one side and an adhesive layer on a surface of the substrate having no raised portion, measured at a cut-off value of 250 μm according to JIS B0601. wrap film ten-point average roughness and height of the ridges defined by (R _Z) may be smaller than the larger substrate thickness than the thickness (D) of the pressure-sensitive adhesive layer (B). 2. JIS B06 on the inclined side surface of the raised portion
2. The wrap film according to claim 1, wherein the wrap film has a fine valley having an average interval ( _Sm ) of 50 nm or more and less than 400 nm measured at a cutoff value of 4 μm according to No. 01. 3. The volume and bottom of the ridge peak portion divided by the adhesive layer thickness (D) from the peak on the peak line of the maximum height (R _y ) measured at a cutoff value of 250 μm according to JIS B0601. The area ratio of the sum of the side areas of the peak portion of the raised portion calculated from the area by the conical approximation to the evaluation plane (substrate projection plane) is 5% or more and 65% or less. 3. The wrap film according to any one of items 2. 4. The pressure-sensitive adhesive layer according to claim 1, wherein a high-adhesion part and a low-adhesion part are mixed on the surface of the pressure-sensitive adhesive layer.
4. The wrap film according to any one of items 3 to 3. 5. The surface of the pressure-sensitive adhesive layer is JIS Z02.
90 degree peeling adhesive strength measured according to 37, 1 to 15 g / 25 mm width in low adhesive part, 300 to 6 in high adhesive part
00g / 25 mm width, and the area ratio of the highly adhesive portion to the evaluation plane (the adhesive layer projection plane) is 25% or more and 65% or more.
5. The wrap film according to claim 4, wherein the wrap film is in a range of not more than%. 6. A sea-island structure in which a high-adhesion portion is continuously connected to the surface of the pressure-sensitive adhesive layer, and a low-adhesion portion is independently dispersed. A wrap film according to the item. 7. The surface of the pressure-sensitive adhesive layer has a low-adhesion part in a circular shape.
7. The wrap film according to claim 6, wherein the wrap film is arranged in a staggered manner at 0 degrees. 8. The wrap film according to any one of claims 4 to 6, wherein the surface of the highly adhesive pressure-sensitive adhesive layer has a low-adhesion part in which a part of the filler is surfaced. 9. The pressure-sensitive adhesive layer according to claim 4, wherein the pressure-sensitive adhesive layer is formed by laminating a pressure-sensitive adhesive through-hole base material on the pressure-sensitive adhesive to form a surface with a higher pressure-sensitive adhesive portion than the through-hole portion. Item 14. The wrap film according to any one of the items. 10. The pressure-sensitive adhesive layer according to claim 4, wherein the surface of the pressure-sensitive adhesive layer has a high pressure-sensitive adhesive part made of a heat-sensitive pressure-sensitive adhesive having a partially thermally activated delayed tack property. The wrap film according to any one of the above.