JP2002002777A - Adhesive wrapping film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a household wrapping film having both excellent hermetic sealability and easiness in drawing out. SOLUTION: The adhesive wrapping film includes an adhesive layer and a surface layer on which pores are provided on at least one of surfaces of the adhesive layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wrapping film used for simple wrapping of foods and the like, which is preferably used as a wrapping film, particularly for household use, and more particularly to a wrapping film containing a liquid food. The present invention relates to a wrapping film for a house hold, which has a sufficient tight-sealing property to prevent contents (liquid food) from spilling into a container and has improved drawability.

[0002]

2. Description of the Related Art Conventionally, a wrapping film for a household 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 wrapping films have not only transparency, but also a moderate elastic modulus during packaging, storage and heating, melt perforation during heating, large deformation,
It is required to have stability without fusing to the container, deformation of the container itself, etc., and proper adhesion between the wraps and the container from a low temperature to a high temperature range. Currently, as a commercially available wrapping film for household, a stretch film mainly composed of the most convenient polyvinylidene chloride-based resin, and other polyethylene-based resins which are significantly inferior in wrap suitability described later, plasticized polyvinyl chloride-based 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. Wrapping film for the past has never existed. The term "adhesive seal" as used herein refers to the adhesion between the food container and the wrap film, and the "pull-out property" refers to the wrapping between the wrapping films when the wound wrap film in the decorative box is pulled out of the box. It means peelability.

[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 wound wrapping film). While there is a demand for a high degree of close-adhesiveness so that the liquid in the contents does not spill out of the container when carrying in and out from the container, the high degree of close contact between the unwrapped wrapping films when used by consumers The drawability of the film decreases, and when the consumer who purchases the film attempts to pull out the wrapping film in a kitchen in the middle of winter (for example, at 5 ° C.), the film may break. In the present invention, it is an object of the present invention to solve such a problem and to provide a wrapping film for a house hold that has a high degree of close sealing property and is excellent in pull-out property.

[0004]

Means for Solving the Problems The inventors of the present invention have made intensive studies from the viewpoints of close contact sealability and drawability, and as a result, have provided a specific perforated surface layer on at least one surface of the pressure-sensitive adhesive layer. Wrapping film materials have been found to be the most suitable. That is, the present invention has the following features. [1] A pressure-sensitive adhesive wrapping film having a surface layer that is perforated on at least one surface of the pressure-sensitive adhesive layer. [2] The pressure-sensitive adhesive wrapping film according to [1], wherein the pressure-sensitive adhesive layer is capable of adhering to the adherend through the opening portion by a pressing force at the time of sticking the wrapping film. [3] The thickness of the surface layer is from 50% to the thickness of the pressure-sensitive adhesive layer.
The adhesive wrapping film according to [1] or [2], which is 200%. [4] The open area ratio of the opened surface layer is 10% to 60%
The adhesive wrapping film according to [1] to [3].

Hereinafter, the contents of the present invention will be described. The most different point of the present invention from the prior art is that a specific perforated surface layer is provided on at least one surface of the pressure-sensitive adhesive layer. The role of the constituent element of the present invention, which is different from the above-mentioned prior art, is the drawability (pulling force: 65) without blocking at the time of drawing in the form of a wound wrapping film.
g / 300 mm width or less), but the consumer has a high degree of close sealing property so that the liquid does not spill out of the container during use. It is to derive appropriately.

The pressure-sensitive adhesive used in the pressure-sensitive adhesive layer of the present invention generally means "adhesion to another surface with very weak pressure such as light finger pressure without the need for water, solvent or heat." Adhesives that can be easily peeled off without contaminating the adherend when they are peeled off again, such as rubber-based adhesives, acrylic-based adhesives, vinyl ether-based adhesives, and silicone-based adhesives. , And a heat-sensitive adhesive having delayed tack performance.

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.

[0008] An acrylic pressure-sensitive adhesive is a main monomer which gives tackiness typically represented by a homopolymer having a low Tg, such as an alkyl acrylate, an acrylate of a lower alkyl group, 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); 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 adhesive is a homopolymer such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether or a copolymer with an 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.

A 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 the heating source is removed. It lasts, and preferably includes the following configurations (a) to (c). (A) a thermoplastic substance (adhesive elastomer), which is a main component that imparts adhesive strength, a heat-fusible substance (solid plasticizer) that has an action of melting by heating to exhibit adhesiveness to the adhesive elastomer, and And a tackifier for further improving the tackiness. For example, there is a thermoplastic compound represented by a natural rubber obtained by graft copolymerization of a vinyl monomer with a solid plasticizer such as dicyclohexyl phthalate and a tackifier such as rosin ether as a heat-fusible substance. (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). This is a pressure-sensitive adhesive composition in which islands are reversed to change into a sea-island structure in which the non-adhesive component is an island and the adhesive component is the sea.

For example, as a non-adhesive component, a water-soluble methyl methacrylate / styrene / acrylic acid copolymer ammonia water neutralized product, which is a substantially non-crosslinkable resin whose acid value is neutralized with a base, There is a mixture of a mixture of an emulsion polymer mainly composed of (meth) acrylate having a Tg of -20 ° C or lower and solid fine particles at ordinary temperature. (See Japanese Patent Application Laid-Open No. 11-228927) (c) The pressure-sensitive adhesive layer is stretched (and the entire substrate is included) and rapidly cooled to induce the oriented crystallization of the adhesive elastomer of the pressure-sensitive adhesive layer, whereby the pressure-sensitive adhesive is adhered. Make the entire agent layer low tack. 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. (See JP-T-2000-502379)

The perforated surface layer of the present invention is provided on at least one surface of the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive force at the time of adhesion of the wrapping film allows the adhesive portion and the non-adhesive portion to exist on the film surface in a specific ratio. As a result, it has a function of exhibiting a specific adhesive strength as an adhesive wrapping film.
Here, the pressing force at the time of adhesion is a pressing force applied in a direction substantially perpendicular to the film to adhere the wrapping film of the present invention, and is 10 g / square centimeter to 1000 g for a normal household wrapping film. / Square centimeter. The preferred range is 10-500 g / cm 2.

The perforated surface layer of the present invention has a small adhesive strength when the pressing force is less than 10 g / cm 2,
When the wound film is pulled out, it can be easily pulled out. The composition of the perforated surface layer is not particularly limited, and is not particularly limited as long as it is used for food packaging. For example, a polyethylene resin, a polypropylene resin, a polybutene-1 resin, Poly-4
-Polyolefin resin (PO) including -methylpentene-1 resin or ethylene-vinyl acetate copolymer resin, ethylene-methyl methacrylate copolymer resin, ethylene-vinyl alcohol copolymer resin (EV
OH) and other modified polyolefin resin (P
O-modified), polyethylene terephthalate (including modified)
Resin, partially containing an aromatic component such as polybutylene terephthalate (modified) resin, or a polyester resin (PEST) of an aliphatic component such as a polylactic acid resin or a polyglycolic acid resin; Chlorine resins such as vinylidene chloride resin and polyvinyl chloride resin, α-olefin-carbon monoxide copolymer resin (including hydrogenated resin), α-olefin (ethylene and others) -styrene copolymer resin (including Hydrogenated resin), ethylene-cyclic hydrocarbon compound copolymer resin (containing hydrogenated resin), polyamide resin,
It is made of a resin composition selected from at least one of caprolactone resins and the like, and contains known additives such as antioxidants, light stabilizers, antistatic agents, antifogging agents, coloring agents, lubricants and the like. The perforated surface layer is a layer that affects the usability of the film when using the adhesive wrapping film of the present invention.For example, when providing a stiff film, a resin having a high elastic modulus is used. When providing a flexible film, a resin having a low elastic modulus may be selected. When the resin is used for heating in a microwave oven or the like, a resin having a high heat-resistant temperature is selected. If these required characteristics cannot be achieved with a single surface layer having a hole, the surface layer may be formed of two or three or more layers.

The composition of the perforated surface layer may be appropriately selected from the above resins and used, but it is necessary that the pressure-sensitive adhesive force at the time of adhesion allows the adhesive to adhere to the adherend through the perforated portion. There is. Here, in order for the pressure-sensitive adhesive to adhere to the adherend through the opening, the surface layer moves below the surface of the pressure-sensitive adhesive layer, that is, a part or all of the surface layer is buried in the pressure-sensitive adhesive layer. . If the amount of burial of the perforated surface layer into the pressure-sensitive adhesive layer is small, the adhesive strength as a wrapping film tends to be small. Conversely, if the amount of burial of the perforated surface layer is large, lapping is performed with a small pressing force. Adhesive strength as a film is developed, and the wound film cannot be easily pulled out. Therefore, the amount of movement (burial) of the perforated surface layer into the pressure-sensitive adhesive layer is from 20% to less than the thickness of the perforated surface layer.
90% is a preferable value, and more preferably 20% to 8%.
0%, more preferably 30% to 80%. If the amount of movement is less than 20%, a predetermined adhesive force cannot be exhibited, and if it is used for a container containing a liquid, water leakage may occur. On the other hand, if the moving amount is larger than 90%, the adhesive strength between the wound films becomes too large, and it may be difficult to pull out the film. The amount of movement of the perforated surface layer below the surface of the pressure-sensitive adhesive layer is also affected by the viscoelastic properties of the pressure-sensitive adhesive layer.
The pressure-sensitive adhesive layer has a viscoelastic property of preferably 0.5 MPa to 3 MPa, more preferably 1 MPa to 3 MPa, still more preferably 1 MPa to 2 MPa as a shear storage modulus at room temperature (23 ° C.). If the shear storage modulus value is less than 0.5 MPa, the pressure-sensitive adhesive layer may be too easy to flow at room temperature, and the pressure-sensitive adhesive flows from the opening of the surface layer to the wrapping film surface at the winding tension during winding. As a result, the film is blocked and drawing out becomes difficult. On the other hand, if the shear storage modulus is more than 3 MPa, the surface layer that has been opened cannot move below the surface of the pressure-sensitive adhesive layer due to the pressing force at the time of adhesion, so that a predetermined pressure-sensitive adhesive force may not be exhibited.

The thickness of the perforated surface layer of the present invention is preferably 50% to 200%, more preferably 50% to 150%, and still more preferably 50% with respect to the thickness of the pressure-sensitive adhesive layer. １００100%. If it is less than 50%, the adhesive force tends to fluctuate due to a slight change in the amount of movement of the perforated surface layer below the surface of the adhesive layer, and a large adhesive force is generated between the films due to the winding tension during winding. Withdrawals can be difficult. On the other hand, if it is larger than 200%, the amount of movement of the perforated surface layer beneath the surface of the pressure-sensitive adhesive layer becomes small, and a predetermined adhesive force may not be exhibited.

The hole area ratio of the hole surface layer of the present invention is preferably 10% to 60%, more preferably 1% to 60%.
It is 5% to 60%, more preferably 20% to 50%.
Here, the perforation means that a circular, square, irregular, or a mixture of these exists in the surface layer, and the perforation method is a physical perforation by a heated needle roll. Drilling with energy rays such as lasers and electron beams can be used. In addition, the surface layer having holes may be formed on a film made of a fibrous material such as a non-woven fabric, in addition to the film obtained by performing the perforating process on the film as described above. If the open area ratio is less than 10%, it becomes difficult to develop a predetermined adhesive force due to the pressure contact force at the time of adhesion. On the other hand, if it is larger than 60%, the films may be blocked by each other due to the winding tension at the time of winding, and the drawing may be difficult.

The pressure-sensitive adhesive wrapping film of the present invention has a preferable pressure-sensitive adhesive force generated by pressing force at the time of adhesion in a range of 15 g / 25 mm width to 250 g / 25 mm width, more preferably 30 g / 25 mm width to 200 g / 2.
5 mm width, more preferably 50 g / 25 mm width to 150
g / 25 mm width. If the adhesive strength is less than 15 g / 25 mm width, the sealing property is poor, and there is a risk of liquid leakage when wrapping a container or the like containing liquid contents. On the other hand, if the adhesive strength is more than 250 g / 25 mm width, the films may be blocked by each other due to the winding tension at the time of winding the film, and it may be difficult to draw out the film.

An example of the method for producing the adhesive wrapping film of the present invention will be described below. The pressure-sensitive adhesive wrapping film of the present invention can be produced by using a usual method for producing a pressure-sensitive adhesive tape. First, the pressure-sensitive adhesive layer composition of the present invention is formed by coating the pressure-sensitive adhesive layer of the present invention on a suitable base film having low tackiness (which is used as a release layer or a release tape in the production of a pressure-sensitive adhesive tape) and then opening the film. The perforated surface layer is stuck on the adhesive. When the perforated surface layer is provided on both sides of the pressure-sensitive adhesive layer, one perforated surface layer is laminated on one side, and then the base material film is peeled off.
The second perforated surface layer is laminated. The coating of the pressure-sensitive adhesive layer depends on the composition used for the pressure-sensitive adhesive layer.However, in the case of a general rubber-based pressure-sensitive adhesive, tackifier, and softener mixture composition, either solution-type coating or emulsion-type coating is used. However, reverse roll coating or doctor blade coating is used. The perforated surface layer film is bonded after the coating of the pressure-sensitive adhesive layer is completed, but the perforation may be performed in-line or a film opened off-line may be used. The hole opening method is generally a method using a heating needle, but may be a hole opened by a laser or an electron beam. The film composed of the pressure-sensitive adhesive layer and the perforated surface layer is once wound into a long length, cut into a predetermined width and length, and then packaged in a dispenser equipped with a cutting device to become a product.

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 adhered to a clean and smooth glass plate, and was pressed from the top of the test piece using a 2000 g pressure roller in three reciprocations, and then peeled off at 90 degrees to measure the adhesive strength. (Unit: g
/ 25mm width)

<< Liquid sealability >> The test method is 200 mm
A wrap 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 70 mm and a height of 150 mm filled with 200 g of water. After holding down the outer surface near the part by hand and sticking it, tilt it 180 degrees for 10 seconds so that the glass cup opening is on the lower side, and then return to the original state with the glass cup opening on top The state when the test piece was peeled off from the glass cup by hand and the state of the test piece when the test piece was peeled off (at the time of peeling) were observed, and evaluated as follows. Evaluation symbol Judgment ◎ The test piece did not come off the glass cup and no water leaked. The wrap film does not break when peeled. ○ The test piece did not peel off from the glass cup, but a little water leaked. Also, the wrap film does not break when peeled. △ The test piece did not peel off from the glass cup, but a little water leaked. Also, the wrap film breaks when peeled. C: The test piece was peeled off from the glass cup.

<Pullability> A bearing-type free roll composed of a driving part (1 in FIG. 1) having a length of about 31 cm and a diameter of about 3.6 cm and a fulcrum shaft (2 in FIG. 1) having a length of 33 cm is wound. The wound wrap film is inserted into the paper tube (3 in FIG. 1) 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. 1), with the hanger (4 in FIG. 1) suspended on the load cell side above the M-200 and its fulcrum axis (2 in FIG. 1) parallel The fulcrum shaft (2 in FIG. 1) is fixed to a bearing (6 in FIG. 1) installed on the pull-down movable body (5 in FIG. 1) below the tester so that the center in the width direction is located, Furthermore, a wrap film integrated with the free roll (Fig. 1
7) is peeled off and fixed to a hanger (4 in FIG. 1) suspended on the load cell side above the tester with a double-sided tape without wrinkles. Then, in a constant temperature room at 5 ° C., the pull-down movable body (5 in FIG.
1 / min and peel off the wrap film (7 in FIG. 1) vertically from the paper tube (3 in FIG. 1). In this case, the peak value of the force required to peel the wrap film (7 in FIG. 1) from the paper tube (3 in FIG. 1) is used as a measured value of the pull-out property (unit: g / 30 cm width) as follows. Was evaluated. Evaluation symbol Peak value Judgment ◎ 65 or less Satisfactory withdrawability, excellent level ○ 65, 80 or less Good withdrawability, practical level △ 80, 100 or less Poor drawability, practical There is an upper problem × 100

<Shear Storage Modulus> As a measuring device, a viscoelasticity measuring device “DSR” manufactured by Rheometric Scientific F.E. was used. The measurement was performed at a temperature of 20 ° C. to 100 ° C., parallel plate shearing (plate interval 1.5 mm), and a frequency of 10 Hz, and the value at 23 ° C. was read from the obtained shear storage modulus curve.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments.

[0024]

Example 1 A commercially available silicone resin-based film (thickness: 1000 μm) was used as a base film, and a film in which the following pressure-sensitive adhesive composition was applied to one surface thereof as a pressure-sensitive adhesive layer with a Meyer bar at about 40 μm was obtained. . Next, a commercially available polypropylene film (thickness 4
0 micron, pore diameter 0.2 mm, opening area ratio 10%) on a pressure-sensitive adhesive layer with a laminator, and then the base film was peeled off, and the same hole was opened on the surface of the peeled pressure-sensitive adhesive layer. The resulting films were laminated to obtain a three-layer film consisting of a perforated surface layer / adhesive layer / perforated surface layer. Adhesive composition: 100 parts of synthetic rubber elastomer, 100 parts of tackifier (hydrogenated terpene resin), 30 parts of softener (process oil)

[0025]

Example 2 A perforated film formed into a net shape (composition: polypropylene, thickness: 4) was used as a perforated surface layer.
A film was obtained in the same manner as in Example 1 except that 0 μm, a regular triangular hole shape, and a hole area ratio of 30% were used.

[0026]

Example 3 A perforated film formed into a net shape (composition: polypropylene, thickness: 4
A film was obtained in the same manner as in Example 1 except that 0 μm, a regular triangular hole shape, and a hole area ratio of 40%) were used.

[0027]

Example 4 An apertured film formed into a net shape (polypropylene, thickness 4
A film was obtained in the same manner as in Example 1 except that 0 μm, a regular triangular hole shape, and a hole area ratio of 60% were used.

[0028]

Example 5 The thickness of the perforated surface layer film was set to 20.
A film was obtained in the same manner as in Example 2 except that the film thickness was changed to microns.

[0029]

Example 6 The thickness of the perforated surface layer film was 60
A film was obtained in the same manner as in Example 2 except that the film thickness was changed to microns.

[0030]

Example 7 The thickness of the perforated surface layer film was 80
A film was obtained in the same manner as in Example 2 except that the film thickness was changed to microns.

[0031]

Comparative Example 1 A film was obtained in the same manner as in Example 1 except that the hole area ratio of the opened surface layer was 5%.

[0032]

[Comparative Example 2] The open area ratio of the opened surface layer was 70%.
A film was obtained in the same manner as in Example 2, except that

[0033]

Comparative Example 3 A film was obtained in the same manner as in Example 2, except that the thickness of the perforated surface layer was changed to 16 μm.

[0034]

Comparative Example 4 A film was obtained in the same manner as in Example 2 except that the thickness of the perforated surface layer was changed to 100 μm.
Table 1 shows the results of evaluation of the adhesive sealing properties and the pull-out properties of each of the films obtained above. From the results shown in Table 1, the pressure-sensitive adhesive wrapping films of the present invention (Examples 1 to 7) have excellent adhesive sealing properties, that is, high adhesive strength, and excellent liquid sealing properties without water leakage from the container containing the liquid substance. It can be seen that the film has excellent drawability from the wound film. On the other hand, the films of Comparative Examples 1 to 4 were films in which it was difficult to achieve both the adhesion and the sealing properties.

[0035]

[Table 1]

[0036]

The pressure-sensitive adhesive wrapping film of the present invention is a film formed from a wound film while sufficiently maintaining a tight sealing property that does not cause spillage of contents (liquid food) to a container containing liquid food or the like. This is a wrapping film having greatly improved usability and improved usability, and is useful as a wrapping film for home use.

[Brief description of the drawings]

FIG. 1 is a schematic front view showing a method of 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

Claims (4)

[Claims] 1. A pressure-sensitive adhesive wrapping film having a surface layer that is perforated on at least one side of a pressure-sensitive adhesive layer. 2. The pressure-sensitive adhesive wrapping film according to claim 1, wherein the pressure-sensitive adhesive layer is capable of adhering to the adherend through the opening portion by a pressing force at the time of sticking the wrapping film. 3. The pressure-sensitive adhesive wrapping film according to claim 1, wherein the thickness of the surface layer is 50% to 200% of the thickness of the pressure-sensitive adhesive layer. 4. An open area ratio of the opened surface layer is 10%.
The pressure-sensitive adhesive wrapping film according to any one of claims 1 to 3, which has a content of from 60 to 60%.