JP5458991B2 - Matte laminated film and packaging material comprising the film - Google Patents

Description

  The present invention relates to a packaging material for packaging foods, miscellaneous goods, magazines, etc., and can be used as a mat without being printed in detail on the surface or laminating Japanese paper or the like. The present invention relates to a (matte) laminated film and a packaging material comprising the film.

  In recent years, with the diversification of designs required for packaging materials, there is an increasing need for matte film having a matte surface on the packaging of bread and other foods. The matte tone film has a texture close to that of Japanese paper compared to a general transparent film, and thus brings out a high-class feeling of the contents. Recently, matte film is also commonly used as a packaging material other than food, so packaging manufacturers can apply matte printing with higher haze to transparent films or laminate Japanese paper. Have been selling differentiated products. However, from the viewpoint of environmental protection and productivity improvement, it is an urgent issue to reduce the weight and thickness of the packaging material, and it does not impair the characteristics of the conventional packaging material, and the film has a higher matte tone as a single unit. Is required.

  In order to respond to such diversification of needs, the present inventors have already provided a matte film having a high haze and good surface slipperiness by a multilayer film (for example, Patent Document 1). reference.). In Patent Document 1, a plurality of different propylene resins are mixed in the surface resin layer to improve the haze as a matte tone, and a slip agent is blended to ensure surface slipperiness. However, the haze is about 70%, a higher matte feeling cannot be obtained, and productivity (cost, complexity of raw material procurement, uniformity of the obtained film, etc.) from the point of using a slip agent together. Therefore, a further improvement method is demanded.

JP 2004-58503 A

  An object of the present invention has been made in view of the above-described problems, and printing and other bases are performed without impairing the packaging suitability, mechanical strength, and surface slippery performance required for conventional packaging materials. An object of the present invention is to provide a laminated film and a packaging material made of the film, which can provide a sufficient matte feeling without lamination of materials and without using additives.

  As a result of intensive studies to solve the above problems, the present inventors have found that a resin layer containing a mixture of a propylene resin and high density polyethylene mixed at a specific ratio, and a resin layer containing a propylene resin. The present inventors have found that a film formed by laminating at least two layers expresses a more excellent mat feeling without impairing the performance required for a conventional packaging material.

That is, the present invention contains a propylene resin (a1) and a high density polyethylene (a2) having a melt flow rate of 1 g / 10 min or less, and the propylene resin (a1) and the high density polyethylene (a2). A surface resin layer (A) in which the ratio of use (mass ratio) (a1) / (a2) is in the range of 20/80 to 70/30;
A matt-like laminated film in which a single-layer or multilayer base resin layer (B) containing a propylene-based resin (b1) is laminated, and the JIS of the surface resin layer (A) of the laminated film The present invention provides a mat-like laminated film characterized in that the surface roughness (Ra) based on B-0601 is 0.5 to 2.0, and a packaging material comprising the film.

  The laminated film of the present invention has high rigidity and mechanical strength, can be used alone, and exhibits an unprecedented mat feeling. Furthermore, it can be fused to the base resin layers or the same kind of resin container, and is excellent in surface slipperiness, so that it is excellent in suitability as a packaging material. Therefore, it can be suitably used as a packaging bag for breads that are stored and transported at room temperature, especially for foods used to bring out a sense of quality.

  The surface resin layer (A) in the laminated film of the present invention contains a propylene-based resin (a1) and a high-density polyethylene (a2) having a melt flow rate of 1 g / 10 min or less. As a ratio of use thereof, a mass ratio (a1) between the propylene resin (a1) and the high-density polyethylene (a2) in order to develop a sufficient matte feeling (high haze and low glossiness) in the obtained film. / (A2) is required to be in the range of 20/80 to 70/30. When the use ratio of the high-density polyethylene (a2) is lower than this, it is difficult to obtain the target mat feeling, while when the use ratio is higher than this, the mechanical strength of the obtained film, In particular, the impact strength is insufficient and it is difficult to obtain a packaging bag at a practical level.

  Examples of the propylene resin (a1) include propylene homopolymers, propylene-α-olefin copolymers such as propylene-ethylene copolymers, propylene-butene-1 copolymers, and propylene-ethylene-butene-1. A copolymer, a metallocene catalyst type | system | group polypropylene, etc. are mentioned. These may be used alone or in combination. From the viewpoint of easy matte feeling and surface roughness adjustment in the resulting laminated film, it is preferable to use a propylene homopolymer or a propylene-ethylene block copolymer, and it is particularly preferable to use a mixture of these.

  These propylene resins (a1) preferably have an MFR (230 ° C.) of 0.5 to 30.0 g / 10 minutes and a melting point of 120 to 165 ° C., more preferably MFR (230 ° C. ) Is 2.0 to 15.0 g / 10 min and the melting point is 125 to 162 ° C. If MFR and melting | fusing point are this range, there will be little shrinkage | contraction of the film at the time of bag making, and also the film-forming property of a film will improve.

  The high-density polyethylene (a2) must have a melt flow rate (190 ° C., 21.18 N) of 1 g / 10 min or less. When the melt flow rate exceeds 1 g / 10 min, the film formability is inferior and it is difficult to obtain a uniform film. A particularly preferred melt flow rate is in the range of 0.05 to 0.8 g / 10 min.

Further, the density of the high-density polyethylene (a2) is in the range of 0.935 to 0.970 g / cm ² , from the viewpoint of mat feeling, mechanical strength, film uniformity, and the like of the obtained laminated film. A range of 0.940 to 0.965 g / cm ² is more preferable.

  In the laminated film of the present invention, it is essential that the surface roughness (Ra) of the surface resin layer (A) based on JIS B-0601 is 0.5 to 2.0. By having a surface roughness within this range, a film excellent in surface slipperiness can be obtained without using other components (additives such as a slip agent) in combination. Workability at the time of packing by an automatic packing machine after filling is improved.

  In order to make the range of the surface roughness (Ra), the propylene-based resin (a1) and the high-density polyethylene (a2) may be used in the above-described ratio as described above, and adjustment is particularly necessary. However, it is preferable to use a propylene homopolymer and a propylene-ethylene block copolymer in combination in order to achieve a desired surface roughness more easily.

  The laminated film of the present invention is obtained by laminating the specific surface resin layer (A) described above on a single-layer or multilayer base resin layer (B) containing the propylene-based resin (b1). . By using a film having such a multilayer structure, a matte feeling can be obtained even when used alone, and strength and the like for packaging bag applications can be expressed.

  As the propylene-based resin (b1), any of those exemplified as the propylene-based resin (a1) can be used, and the same or different ones can be used in combination. Thus, the interlayer strength of the laminated film can be increased by using the same resin for the surface resin layer (A) and the base resin layer (B). A propylene-ethylene copolymer can be particularly preferably used. In addition, other olefin-based resins, for example, polyethylene resins such as very low density polyethylene (VLDPE), linear low density polyethylene (LLDPE), and low density polyethylene (LDPE), ethylene, and the like within the range not impairing the effects of the present invention -Vinyl acetate copolymer (EVA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate (EMA) copolymer, ethylene-ethyl acrylate-anhydrous Ethylene copolymers such as maleic acid copolymer (E-EA-MAH), ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA); and ethylene-acrylic acid copolymer Combined ionomer, ethylene-methacrylic acid copolymer ionomer Or the like may be used in combination.

  In particular, when used as a packaging bag, the base resin layer (B) preferably has a multi-layer structure from the viewpoint of excellent balance between mechanical strength and heat sealability, so-called intermediate layer (i) and seal layer. It is preferable that it has the structure which consists of (ii).

  The intermediate layer (i) is an intermediate layer between the sealing layer (ii) and the surface resin layer (A), and increases the strength and rigidity of the resulting laminated film, and the matte feeling of the surface resin layer (A). It is preferable to use a mixture of a propylene-ethylene block copolymer and a linear low density polyethylene from the point that can be more emphasized. The use ratio at this time is more preferably in the range of propylene-ethylene block copolymer / linear low density polyethylene = 95/5 to 70/30.

  The said sealing layer (ii) is designed so that sealing strength can be easily obtained at the time of heat-sealing between sealing layers (ii) of laminated films or containers made of other materials. Depending on the application, the resin type can be selected. In particular, when used as a packaging bag and heat-sealing the sealing layers (ii), it is preferable to contain a propylene-ethylene random copolymer from the viewpoint of obtaining appropriate sealing strength. Furthermore, in order to adjust the seal strength, an ethylene-α-olefin copolymer can be used in combination.

  Since the laminated film of the present invention has sufficient strength as a single film, the total thickness is preferably in the range of 20 to 50 μm, and is used particularly for packaging of relatively light contents such as bread. When doing so, it is preferable that it is 25-40 micrometers.

  Furthermore, in order to give a sufficient matte feeling (high haze and low glossiness) to the laminated film, it is preferable that the surface resin layer (A) is 10 to 30% of the total thickness.

  For each of the resin layers (A) or (B), if necessary, an antifogging agent, an antistatic agent, a thermal stabilizer, a nucleating agent, an antioxidant, a lubricant, an antiblocking agent, a release agent, Components such as an ultraviolet absorber and a colorant can be added as long as the object of the present invention is not impaired.

  Although it does not specifically limit as a manufacturing method of the laminated | multilayer film of this invention, For example, each resin or resin mixture used for a resin layer (A) and a resin layer (B) is heat-melted with a respectively separate extruder, and is co-extrusion. Examples include a co-extrusion method in which the layers are laminated in the order of (A) / (B) in a molten state by a method such as a multilayer die method or a feed block method, and then formed into a film shape by inflation, a T-die chill roll method or the like. This coextrusion method is preferable because the thickness ratio of each layer can be adjusted relatively freely, and a multilayer film excellent in hygiene and cost performance can be obtained. Furthermore, since the difference in melting point between the propylene resin (a1) and the high density polyethylene (a2) used in the present invention is large, the film appearance may deteriorate during coextrusion. In order to suppress such deterioration, a T-die / chill roll method that can perform melt extrusion at a relatively high temperature is preferable.

  Since the laminated film of the present invention is obtained as a substantially unstretched multilayer film by the above production method, secondary molding such as deep drawing by vacuum molding is also possible.

  Further, when printing or the like is performed on the surface resin layer (A), it is preferable to perform a surface treatment on the resin layer (A) in order to improve adhesion with printing ink. Examples of such surface treatment include corona treatment, plasma treatment, chromic acid treatment, flame treatment, hot air treatment, surface oxidation treatment such as ozone / ultraviolet treatment, and surface unevenness treatment such as sandblasting. Corona treatment is preferable.

  Examples of the packaging material comprising the laminated film of the present invention include packaging bags, containers, container lids and the like used for foods, medicines, industrial parts, miscellaneous goods, magazines and the like. In particular, since a mat feeling is unprecedented, a packaging material similar to Japanese paper or the like can be provided, and it can be suitably used for foods used to bring out a high-class feeling.

  The packaging bag uses the base resin layer (B) of the laminated film of the present invention as a heat seal layer, and heat seals the resin layers (B) together, or the resin layer (A) and the resin layer (B). It is preferably a packaging bag formed with the heat-sealing resin layer (B) on the inside by overlapping and heat-sealing. For example, after cutting the two laminated films into the desired size of the packaging bag, overlapping them and heat-sealing the three sides to form a bag, filling the contents from one side that is not heat-sealed It can be used as a packaging bag by heat sealing. Furthermore, it is also possible to form a packaging bag by sealing the top and bottom after sealing the end of a roll film into a cylindrical shape by an automatic packaging machine.

  Moreover, it is also possible to form a packaging bag, a container, and a container lid by heat-sealing a resin layer (B) and another heat-sealable film. In this case, as another film to be used, a film such as LDPE, EVA, or polypropylene having relatively low mechanical strength can be used. Also, a laminate film in which a film of LDPE, EVA, polypropylene, etc., and a stretched film having relatively good tearability, for example, a biaxially stretched polyethylene terephthalate film (OPET), a biaxially stretched polypropylene film (OPP), etc. are bonded together. Can be used.

  Next, the present invention will be described in more detail with reference to examples and comparative examples. Hereinafter, unless otherwise specified, “part” is based on mass.

Example 1
As the surface resin layer (A), 40 parts of a propylene homopolymer (density: 0.90 g / cm ³ , MFR: 9 g / 10 minutes) and high-density polyethylene (density: 0.955 g / cm ³ , MFR: 0.35 g) For 10 minutes) and 20 parts of a propylene-ethylene block copolymer (density: 0.91 g / cm ³ , MFR: 7 g / 10 minutes). Further, as the intermediate layer (i), 90 parts of a propylene-ethylene block copolymer (density: 0.91 g / cm ³ , MFR: 7 g / 10 minutes) and linear low density polyethylene [density: 0.905 g / cm ³ , MFR: 4 g / 10 min] was used. Furthermore, 75 parts of propylene-ethylene copolymer (ethylene-derived component content: 5.8%, density: 0.90 g / cm ³ , MFR: 6 g / 10 min) as a sealing layer (ii) and crystalline ethylene-1- A mixture composed of 25 parts of an octene copolymer (density: 0.88 g / cm ³ , MFR: 3 g / 10 min) was used. These are each supplied to three extruders, and coextruded so that the ratio of the average thickness of the surface resin layer (A), the intermediate layer (i) and the seal layer (ii) is 3: 5: 2, A three-layer film having a thickness of 30 μm was formed. Next, the surface resin layer (A) of the obtained three-layer film was subjected to corona discharge treatment so that the surface energy was 36 mN / m, to obtain a laminated film.

Example 2
As the surface resin layer (A) of Example 1, a co-extruded multilayer film consisting of 3 layers having a thickness of 30 μm was carried out in the same manner as in Example 1 except that 50 parts of propylene homopolymer / 50 parts of high-density polyethylene were used. Obtained. Subsequently, the surface of the surface resin layer (A) of the obtained film was subjected to a corona discharge treatment in the same manner as in Example 1 so that the surface energy was 36 mN / m.

Example 3
The surface resin layer (A) of Example 1 was replaced with 30 parts of propylene homopolymer, 30 parts of high-density polyethylene, and 40 parts of propylene-ethylene block copolymer, and was carried out in the same manner as in Example 1, with a thickness of 30 μm. A laminated film consisting of three layers was obtained. Subsequently, the surface of the surface resin layer (A) of the obtained film was subjected to a corona discharge treatment in the same manner as in Example 1 so that the surface energy was 36 mN / m.

Comparative Example 1
As the surface resin layer (A), a propylene-ethylene block copolymer (density: 0.91 g / cm ³ , MFR: 7 g / 10 minutes) was used, and as the intermediate layer (i), a propylene-ethylene block copolymer ( Density: 0.91 g / cm ³ , MFR: 7 g / 10 min), and propylene-ethylene copolymer (ethylene-derived component content: 5.8%, density: 0.90 g / min) as the sealing layer (ii) A mixture comprising 75 parts of cm ³ , MFR: 6 g / 10 minutes) and 25 parts of a crystalline ethylene-1-octene copolymer (density: 0.88 g / cm ³ , MFR: 3 g / 10 minutes) was used. These are each supplied to three extruders, and coextruded so that the ratio of the average thickness of the surface resin layer (A), the intermediate layer (i) and the seal layer (ii) is 3: 5: 2, A three-layer film having a thickness of 30 μm was formed. Next, the surface resin layer (A) of the obtained three-layer film was subjected to corona discharge treatment so that the surface energy was 36 mN / m, to obtain a laminated film.

Comparative Example 2
The surface resin layer (A) of Comparative Example 1 was prepared in the same manner as in Comparative Example 1 except that 15 parts of propylene homopolymer, 15 parts of high density polyethylene, and 60 parts of propylene-ethylene block copolymer were used. A coextruded multilayer film consisting of 3 layers was obtained. Subsequently, the surface of the surface resin layer (A) of the obtained laminated film was subjected to corona discharge treatment in the same manner as in Example 1 so that the surface energy was 36 mN / m.

  Using the laminated films obtained in Examples 1 to 3 and Comparative Examples 1 and 2, the following tests and evaluations were performed.

Measurement of haze Using the obtained film, haze (unit:%) was measured for one film using a haze meter (manufactured by Nippon Denshoku Kogyo Co., Ltd.) based on JIS K7105.

Measurement of Glossiness Using the obtained film, the glossiness (unit:%) was measured for one sheet using a gloss meter (manufactured by Suga Test Instruments Co., Ltd.) based on JIS K7105.

Measurement of surface roughness (Ra) Using the obtained film, surface roughness (Ra) was measured using SURFCOM 480A manufactured by Tokyo Seimitsu Co., Ltd. based on JIS B-0601.

Measurement of rigidity Using the obtained film, based on ASTM D-882, a 1% tangential modulus (unit: MPa) at 23 ° C. was measured in terms of the extrusion direction (hereinafter referred to as “MD”) during film production. It measured using the testing machine [made by A & D Co., Ltd.].

Measurement of impact strength Using the obtained film, the sample was held for 6 hours in a temperature-controlled room adjusted to 23 ° C., and then measured by a film impact method using a spherical impact head having a diameter of 25.4 mm.

Measurement of Friction Coefficient Value Using the obtained film, the static friction coefficient value and the dynamic friction coefficient value of the side surfaces of the surface layers were measured at 23 ° C. based on ASTM D-1894.

Packaging suitability evaluation Using the obtained film, set in a horizontal pillow packaging machine (“FW-3400 / B αV” manufactured by Fujikikai Co., Ltd.) with the seal layer on the inside, and the upper seal bar temperature at the bottom is 130 ° C. Pillow packaging bags (180 mm long and 150 mm wide) were produced under the conditions of a lower seal bar temperature of 130 ° C., a center (back adhesive part) seal temperature of 140 ° C., and a bag making speed of 60 pieces / min. When packaging the film with a horizontal pillow packaging machine ("FW-3400 / B αV" manufactured by Fujikikai Co., Ltd.), when the film is sent with the horizontal pillow packaging machine, the film does not have a certain degree of rigidity. Due to the center seal misalignment and wrinkles, packaging defects are likely to occur. Also, if the film does not have a certain level of heat resistance, when the film is sealed, the film is fused to the seal bar and cannot be packaged. Therefore, packaging suitability was evaluated according to the following criteria.
○: The rigidity is 600 MPa or more, the friction coefficient value is 0.3 or less, the film is sent without any problem, and the film is not fused to the seal bar.
X: Deviation and wrinkle occur when the film is fed, and there is further fusion to the seal bar.

  The results obtained above are shown in Table 1.

  The laminated film of the present invention exhibits a high matte feeling. It also has excellent packaging suitability, surface slipperiness and mechanical strength. Therefore, the laminated film of the present invention is suitable for food applications that impart design properties and other packaging materials for packaging other chemicals, industrial parts, sundries, magazines, and the like.

Claims (10)

It contains a propylene-based resin (a1) and a high-density polyethylene (a2) having a melt flow rate of 1 g / 10 min or less, and a use ratio (mass) of the propylene-based resin (a1) and the high-density polyethylene (a2). Surface resin layer (A) in which (ratio) (a1) / (a2) is in the range of 20/80 to 70/30;
The intermediate layer (i) containing the propylene resin (b1) and the seal layer (ii),
The intermediate layer (i) comprises a propylene-ethylene block copolymer and a linear low density polyethylene in a range of propylene-ethylene block copolymer / linear low density polyethylene = 95/5 to 70/30. A base-like resin layer (B) that is a mixture, and a mat-like laminated film that is laminated,
The surface resin layer of the laminated film (A), JIS B-0601 in based surface roughness (Ra) Ri is 0.5 to 2.0 der, haze 75% or more, and glossiness is 5% or less matte laminated film characterized Rukoto Oh. The mat-like laminated film according to claim 1, wherein the propylene-based resin (a1) is a mixture of a propylene homopolymer and a propylene-ethylene block copolymer. The mat-like laminated film according to claim 1 or 2, wherein the propylene-based resin (b1) is a propylene-ethylene copolymer. The mat-like laminated film according to any one of claims 1 to 3, wherein the total thickness is in a range of 20 to 50 µm and the single thickness is used alone. The matte laminated film according to any one of claims 1 to 4, wherein the surface resin layer (A) is 10 to 30% of the total thickness. A packaging material comprising the matte laminated film according to any one of claims 1 to 5. The packaging material according to claim 6, which is a packaging bag for food. The packaging material according to claim 7, which is a bread packaging bag having a total thickness of 25 to 40 µm. After stacking two mat-like laminated films according to any one of claims 1 to 5 and heat-sealing three sides to form a bag, the contents are filled from one side that is not heat-sealed and heat-sealed. A method for producing a packaging bag, characterized by being sealed. A method for producing a packaging bag, comprising sealing the end of the matte laminated film according to any one of claims 1 to 5 to form a cylindrical system, and then sealing the top and bottom.