JP4839642B2 - Easy peelable film and lid - Google Patents

Description

  The present invention relates to an easily peelable film and a lid material.

  The lid of the packaging material container is required to be tightly sealed to the container in order to protect the contents, and at the same time be easily opened when opened. As a lid material having such a function, for example, an easily peelable film using a resin composition blended with different kinds of resins is used.

  As a film having easy peelability to a polyester resin container, a heat-sealable polyester resin layer, an olefin / maleic anhydride copolymer layer, and a polyolefin layer are laminated in order, and the heat-sealable polyester layer and the olefin are laminated. An easily peelable film is known that peels between layers with a maleic anhydride copolymer layer (see Patent Document 1). However, when the film is heat-sealed at a low temperature in order to prevent thermal deformation of the polyester resin container, there is a problem that the adhesive strength between the easily peelable film and the container is insufficient. Therefore, as a film having improved low-temperature sealability, it is an easily peelable film comprising a seal layer and a substrate, and the seal layer comprises 60 to 95 parts by weight of a crystalline polyester having a glass transition temperature of 40 ° C. or less and a glass transition temperature. Is easily peelable comprising 5 to 40 parts by weight of amorphous polyester having a temperature of 70 ° C. or less (see Patent Document 2).

Japanese Patent Laid-Open No. 4-94933 JP 2001-328221 A

By the way, as a method for producing a film, an extrusion molding method using a T-die or an inflation molding method is generally used, and the inflation molding method is preferred from the viewpoint of productivity. When a film as described in Patent Document 2 is produced by an inflation molding method, the inner surface of the tubular film extruded from the inflation die needs to be a sealing layer. This is because when the sealing layer is an outer surface, the tube-shaped film may be wrinkled or scratched when it comes into contact with an inflation device such as a safety plate or a steady-state tube before it is nipped by a nip roll. . However, when the film described in Patent Document 2 is formed so that the sealing layer is the inner surface of the tubular film, the inner surfaces of the films are attached to each other when the film is nipped for film take-off. It may be difficult to open a tubular film into a single film.

An object of the present invention is an easily peelable film and a lid material which are easy to form a film in an inflation process and have a good low temperature sealing property and an easily peelable property for use as a container lid material made of a polyester resin. Is to provide.

That is, this invention is an easily peelable film which has a sealing layer which consists of a polyester-type resin composition, Comprising: This polyester-type resin composition is 100 weight part of crystalline polyester (A), and said crystalline polyester (A). It consists of 5 to 45 parts by weight of olefin resin (B), 5 to 25 parts by weight of wax (C) made of a resin different from the crystalline polyester (A) and the olefin resin (B) with respect to 100 parts by weight. An easily peelable film and a lid material using the easily peelable film.

The easily peelable film and lid material of the present invention can be easily formed into a film by inflation, and have good low temperature sealability and easy peelability for use as a container lid material made of polyester resin. It is.

The seal layer in the easily peelable film of the present invention is a layer that is heat-sealed with the container when the easily peelable film is used as a lid for the container. The sealing layer in the easily peelable film of the present invention is a polyester containing a wax comprising a crystalline polyester (A), an olefinic resin (B), a resin different from the crystalline polyester (A) and the olefinic resin (B). It consists of a resin composition. The crystalline polyester (A) is produced by polycondensation of a dibasic acid and a polyhydric alcohol. Examples of the dibasic acid include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid, and aliphatic dicarboxylic acids such as adipic acid. Examples of the polyhydric alcohol include diols such as ethylene glycol, butanediol, 1,4-cyclohexanedimethanol, pentaethylene glycol, 2,2-dimethyltrimethylene glycol, hexamethylene glycol, and neopentyl glycol. Said dibasic acid and polyhydric alcohol are used by arbitrary combinations. Specifically, terephthalic acid / ethylene glycol copolymer, terephthalic acid / ethylene glycol / 1,4-cyclohexanedimethanol terpolymer, 2,6-naphthalenedicarboxylic acid / ethylene glycol copolymer, terphthalic acid / And isophthalic acid / butanediol terpolymer. The crystalline polyester (A) used in the present invention preferably has a melting point of 100 to 180 ° C and a glass transition temperature of 10 ° C or less from the viewpoint of inflation moldability. Examples of such a crystalline polyester include a resin marketed under the trade name “Byron” (Toyobo Co., Ltd.).

The crystalline polyester in the present invention is a resin in which a crystallization peak and / or a melting peak is observed by the following method.
Using a differential scanning calorimeter (DSC220C manufactured by Seiko Denshi Kogyo Co., Ltd.), the melting behavior of the resin is measured under the following conditions. In each step, time is plotted on the horizontal axis, and the heat of fusion is plotted on the vertical axis to obtain a melting curve. The peak observed in the step (ii) is the crystallization peak, and the peak observed in the step (iii) is the melting peak. And
(I) About 5 mg of a sample is heated from room temperature to 200 ° C. at a rate of 30 ° C./minute, and is held for 5 minutes after the temperature increase is completed.
(Ii) Next, the temperature is decreased from 200 ° C. to −100 ° C. at a rate of 10 ° C./min, and held for 5 minutes after the completion of the temperature decrease.
(Iii) Next, the temperature is raised from −100 ° C. to 200 ° C. at a rate of 10 ° C./min.

Examples of the olefin resin (B) include propylene resins such as propylene homopolymer, propylene / α-olefin block copolymer, propylene / α-olefin random copolymer, and polyethylene such as low density polyethylene and high density polyethylene. , Ethylene / α-olefin copolymers such as ethylene / butene-1 copolymer and ethylene / hexene-1 copolymer, ethylene / propylene copolymer, ethylene / methyl methacrylate copolymer and ethylene / vinyl acetate copolymer Examples thereof include ethylene-based resins such as ethylene copolymers composed of a structural unit derived from one or more vinyl monomers such as a coalescence and a structural unit derived from ethylene.
As the olefin resin (B), two or more kinds of resins may be used. In that case, it is preferable to select two or more kinds from the same kind of resin, for example, a propylene resin. Examples of the α-olefin in the present invention include α-olefins having 4 to 10 carbon atoms such as butene-1 and octene-1. As the olefin resin (B), a propylene resin is preferably used. From the viewpoint of peelability and heat resistance, a propylene homopolymer or a propylene / α-olefin random copolymer having an α-olefin unit content of 50% by weight or less. It is preferable to use coalescence.

Examples of the vinyl monomer include unsaturated carboxylic acids such as acrylic acid and methacrylic acid, unsaturated carboxylic acid esters such as ethyl acrylate, methyl acrylate and ethyl methacrylate, and unsaturated carboxylic acid anhydrides such as maleic anhydride. Can be mentioned. When an ethylene copolymer comprising a structural unit derived from one or more vinyl monomers and a structural unit derived from ethylene is used as the olefin resin (B) constituting the seal layer, the configuration derived from ethylene in the ethylene copolymer The content of the component is preferably 80 to 95% by weight.

The wax (C) in the present invention is made of a resin different from the crystalline polyester (A) and the olefin resin (B). Examples of the wax (C) include synthetic waxes such as ethylene resin wax, propylene resin wax and Fischer-Tropsch wax, petroleum waxes such as paraffin wax and micro wax, natural waxes such as wood wax, carnapa wax and beeswax. Can be mentioned. The wax (C) preferably has a weight average molecular weight of 500 to 5000 determined by the GPC method from the viewpoint of film processability and peelability of the obtained film, and is a polyethylene having a weight average molecular weight of 500 to 5000. More preferred. More preferably, the olefin resin (B) contained in the polyester resin composition is a propylene resin, and the wax (C) is polyethylene having a weight average molecular weight of 500 to 5,000.

The polyester-based resin composition constituting the sealing layer is composed of 100 parts by weight of crystalline polyester (A) and 5 to 45 parts by weight of olefin resin (B) with respect to 100 parts by weight of crystalline polyester (A), wax ( C) It preferably consists of 5 to 25 parts by weight. When the ratio of the olefin resin (B) in the polyester resin composition is out of the above range, the easy peelability is inferior when the easily peelable film is used as a lid for a container made of a polyester resin. . On the other hand, if the proportion of the wax (C) in the polyester resin composition is less than 5 parts by weight, the film surface becomes very sticky, and it is particularly difficult to form a film by inflation molding. The proportion of the total weight of the crystalline polyester (A), the olefin resin (B) and the wax (C) in the polyester resin composition is usually 90% by weight or more. The polyester-based resin composition is a resin other than the above (A), (B), and (C), a compatibilizer, a lubricant, an antistatic agent, an antioxidant, and a heat stabilizer, as long as the effects of the present invention are not impaired. , UV absorbers, antibacterial agents, antifogging agents and the like may be included.

The easily peelable film having a sealing layer made of a polyester-based composition may be a single-layer film made only of the sealing layer, but is preferably a laminated film from the viewpoint of film processing stability. In the case of a laminated film, the adjacent layer adjacent to the seal layer is preferably composed of one or more olefin-based resins. As the olefin resin, the resin exemplified as the olefin resin (B) in the seal layer can be used. As the resin constituting the adjacent layer, it is more preferable to use an ethylene-based resin. However, when an ethylene copolymer composed of one or more vinyl monomer-derived structural units and ethylene-derived structural units is used in the adjacent layer, the content of ethylene-derived structural components in the ethylene copolymer is from 60 to It is preferably 95% by weight.

When the easily peelable film of the present invention is a laminated film, the thickness of the seal layer in the total thickness of the easily peelable film is preferably 3 to 70%, more preferably 5 to 50%. . If the thickness of the sealing layer is too thin, there is a tendency that the sealing strength with the container tends to be insufficient when the easily peelable film is used as a container covering material. In some cases, the resin constituting the resin is stretched and the appearance after peeling is impaired.

  The adjacent layer in the present invention may contain a polystyrene resin, a polyamide resin, a polyester resin, or the like. Further, a compatibilizer, an antioxidant, a heat stabilizer, an ultraviolet absorber, an antibacterial agent, an antifogging agent and the like may be contained.

The easily peelable film of the present invention can be produced by a known method. For example, in the case of a single-layer film consisting only of a seal layer, it can be produced by an inflation molding method, a T-die cast molding method or the like, and in the case of a laminated film, a co-extrusion inflation molding method, a co-extrusion method, or the like. It can be produced by a T-die cast molding method, a coextrusion laminate molding method, or the like. From the viewpoint of productivity, it is preferable to produce by an inflation molding method or a coextrusion inflation molding method. Although the thickness of an easily peelable film is not specifically limited, Usually, in the case of a single layer, it is 10-100 micrometers, and in the case of a laminated film, a seal layer is 3-80 micrometers.

The easily peelable film of this invention may have one or more base material layers in the surface which is not adjacent to the sealing layer of an adjacent layer. Examples of the material constituting the base material layer include thermoplastic resin, aluminum foil, and paper.

Examples of the thermoplastic resin constituting the base material layer include olefin resins, polyester resins, polyamide resins, and the like used in the seal layer. As the olefin resin, the resin exemplified as the olefin resin (B) in the seal layer can be used. However, when an ethylene copolymer composed of one or more vinyl monomer-derived constitutional units and ethylene-derived constitutional units is used as the resin constituting the base material layer, the inclusion of ethylene-derived constitutional components in the ethylene copolymer The amount is preferably 80 to 95% by weight. Such an easily peelable film having a base material layer composed of an ethylene copolymer composed of one or more vinyl monomer-derived constitutional units and ethylene-derived constitutional units has excellent adhesion between the base material layer and the adjacent layer. The appearance after peeling the easily peelable film from the container can be made better.

  The base material layer may be provided by coextrusion together with the seal layer and the adjacent layer, or may be laminated on the adjacent layer by an extrusion laminate molding method, and a pre-formed film is adjacent by a method such as a dry laminate molding method. You may laminate | stack on a layer. Examples of the preformed film that can be used as the base layer include thermoplastic resins such as biaxially stretched polyester film, biaxially stretched polyamide film, biaxially stretched polypropylene film, and biaxially stretched ethylene-vinyl alcohol copolymer film. Film, a film made of thermoplastic resin, a film provided with a printing layer, a coating layer, and a vapor deposition layer, aluminum foil, paper, and the like. For example, when an aluminum foil is laminated on an adjacent layer, a surface treatment such as corona treatment is applied to the adjacent layer surface of the laminated film in which the adjacent layer and the seal layer are laminated, and an adhesive is applied to one surface of the aluminum foil. Apply. Then, after the corona-treated surface of the laminated film and the adhesive surface of the aluminum foil are pressure-bonded with a dry laminator, aging is performed to obtain an easily peelable film in which the base material layer, the adjacent layer, and the seal layer are sequentially laminated. be able to.

The seal layer in the easily peelable film of the present invention is excellent in transparency. Therefore, an easily peelable film having excellent transparency can be obtained by selecting a resin having excellent transparency as the resin constituting the adjacent layer and the base material layer. From the viewpoint of transparency of the easily peelable film, the resin constituting the adjacent layer is preferably an ethylene copolymer having an ethylene-derived constituent content of 60 to 95% by weight, and constitutes a base material layer. The resin to be used is the same type of resin as that of the adjacent layer. For example, if the adjacent layer is an ethylene-based resin, the base layer is preferably an ethylene-based resin.

  The easily peelable film of the present invention is suitably used as a lid for containers, particularly containers made of polyester resins. Moreover, the sealing layer in the easily peelable film of this invention is excellent in transparency. Therefore, when the easily peelable film of the present invention is a single layer or a laminated film obtained by selecting a resin having excellent transparency as the resin constituting the adjacent layer and the base material layer, It is an excellent easily peelable film and can be suitably used as a lid for containers that require transparency, such as a lid for a jelly container or a lid for a frozen confectionery container.

  EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to these Examples at all.

[Example 1]
First, 100 parts by weight of polypropylene (trade name “Noblen FL6412” (manufactured by Sumitomo Chemical Co., Ltd., MI = 6 g / 10 min)) as the olefin resin (B) and 100 parts by weight of the polypropylene as wax (C) A 45 mmΦ twin-screw extruder with the same direction, 67 parts by weight of polyethylene wax (trade name “Neowax L” (Yasuhara Chemical Co., Ltd., weight average molecular weight 750, melting point 110 ° C.)) set to a cylinder temperature and a die temperature of 190 ° C. The resulting mixture was melt mixed to obtain pellets of the resin composition (1). As the crystalline polyester (A), 100 parts by weight of the trade name “Byron GM913” (Toyobo Co., Ltd., melting point 126 ° C., glass transition temperature −70 ° C.) and 100 parts by weight of the crystalline polyester, the resin composition A polyester resin composition for forming a seal layer was obtained by pellet blending 43 parts by weight of the pellet of (1). The composition of the polyester resin composition is 100 parts by weight of crystalline polyester, 26 parts by weight of olefin resin (B) and 17 parts by weight of wax (C) with respect to 100 parts by weight of crystalline polyester (A). there were. In addition, a trade name “ACRlift CG4002” (manufactured by Sumitomo Chemical Co., Ltd., ethylene / methyl acrylate copolymer, content of ethylene-derived constitutional unit 69% by weight) was used for the adjacent layer. Furthermore, linear low density polyethylene (trade name “Evolue FV202” (manufactured by Sumitomo Chemical Co., Ltd., d = 0.925)) was used for the base material layer. Using the above materials, 3 types, 3 layers co-extrusion inflation machine (Extruder A: 50 mmφ, Extruder B: 50 mmφ, Extruder C: 50 mmφ, Layer structure: Tubular film outer surface / middle surface / inner surface = Extruder A / extruder B / extruder C), base layer resin in extruder A, adjacent layer resin in extruder B, and polyester-based resin composition for seal layer in extruder C, extrusion temperature Molded at 180 ° C. to produce a laminated film in which a base material layer, an adjacent layer, and a seal layer were laminated in this order. Further, a corona discharge treatment was performed on the base material layer side of the laminated film so that the wetting tension was 45 dyn / cm. The resulting laminated film had a seal layer thickness of 5 μm, an adjacent layer thickness of 15 μm, a base material layer thickness of 15 μm, and an overall thickness of 35 μm.

[Comparative Example 1]
Three types and three layers are laminated in the same manner as in Example 1 except that a mixture of 100 parts by weight of the crystalline polyester used in Example 1 and 43 parts by weight of polypropylene is used as the polyester resin composition constituting the sealing layer. A film was obtained.
[Comparative Example 2]
As a polyester resin composition constituting the seal layer, 100 parts by weight of the crystalline polyester used in Example 1 and linear low density polyethylene (trade name “Evolu FV403” (manufactured by Sumitomo Chemical Co., Ltd., d = 0. No. 919) 43 parts by weight) was used in the same manner as in Example 1 to obtain a laminated film of 3 types and 3 layers.
[Comparative Example 3]
As the polyester resin composition constituting the sealing layer, a mixture of 100 parts by weight of the crystalline polyester used in Example 1 and 17 parts by weight of wax and 26 parts by weight of the linear low density polyethylene used in Comparative Example 2 was used. Except for the above, a three-layer / three-layer laminated film was obtained in the same manner as in Example 1.
[Comparative Example 4]
As a polyester-based resin composition constituting the sealing layer, 100 parts by weight of the crystalline polyester used in Example 1, 17 parts by weight of the linear low density polyethylene used in Comparative Example 2, and a trade name “PETG6763 which is an amorphous polyester” A three-layer, three-layer film was obtained in the same manner as in Example 1 except that a mixture of 50 parts by weight (manufactured by Eastman Chemical, glass transition temperature 81 ° C.) was used.
[Comparative Example 5]
A three-layer, three-layer laminated film was obtained in the same manner as in Example 1 except that 100 parts by weight of the amorphous polyester used in Comparative Example 4 was used as the resin constituting the sealing layer.

The films obtained in Example 1 and Comparative Examples 1 to 5 were evaluated by the following methods. The results are shown in Table 1.
(1) Easily peelable Using a coater manufactured by Yasui Seiki Co., Ltd., aliphatic ester coating agent (main agent = Takelac XA-525, Mitsui Takeda Chemical Co., Ltd., curing agent = Takenate Mitsui Chemical Co., Ltd., Takenate XA-52 "and ethyl acetate blended at a weight ratio of 10: 1 to 15 respectively and mixed thoroughly) to a polyester film (Unitika Ltd., trade name" PTMX ", thickness 25 μm, width 330 mm) After apply | coating and making it press-fit with the corona treatment surface of each laminated film obtained by the said Example and comparative example, it heated in 40 degreeC oven for 24 hours, and obtained the easily peelable film. As an adherend, a non-crystalline polyester sheet (Toyobo Co., Ltd .: A560GE0R, thickness = 300 μm) cut into 70 × 90 mm was used, and the adherend and the resulting easily peelable film seal layer were used. And was heat-sealed in a strip shape having a width of 20 mm (in a direction parallel to the length of 90 mm of the adherend) at a pressure of 3 kg / cm ² , a time of 1 second and each temperature condition shown in Table 1. A test piece of 15 mm × 70 mm was cut out at a 15 mm width interval so as to include the seal portion perpendicular to the strip-shaped seal portion. Using a Toyo Seiki Co., Ltd. Autograph AGS500D type tensile tester, the peel strength when peeled 180 ° at a tensile rate of 300 mm / min in an atmosphere at 23 ° C. was measured. If peel strength is 5-15N / 15mm width, it can be said that it is excellent in the balance of the sealing strength with a container, and the easy peelability at the time of peeling.

(2) Opening property of tube-like film The opening property of tube-like film is obtained by cutting a test piece from a tube-like film obtained by inflation processing, that is, a tube-like film in a state where seal layers are in contact with each other. It was evaluated whether the inner surfaces (seal layers) of each other could be opened with bare hands or adhesive tape. The case where the seal layers could be easily peeled off was indicated as “◯”, and the case where the seal layers could not be peeled off was indicated as “x”.
(3) Transparency
In accordance with JIS K7105, the total light transmittance and diffuse light transmittance of each easily peelable film prepared in the above (1) easy peel test were measured, and the HAZE value (= (diffuse light transmittance / total light transmittance) was measured. Rate) × 100). The case where the HAZE value was 20 or less was marked with ◯, and the case where it exceeded 20 was marked with ×.

Claims (6)

An easily peelable film having a sealing layer made of a polyester resin composition, wherein the polyester resin composition is 100 parts by weight of crystalline polyester (A) and 100 parts by weight of crystalline polyester (A). propylene-based resin (B) 5 to 45 parts by weight, the crystalline polyester (a) and the easily peelable film comprising a wax (C) 5 to 25 parts by weight of a resin different from that of the propylene-based resin (B).   The easily peelable film according to claim 1, wherein the crystalline polyester (A) contained in the polyester-based resin composition has a melting point of 100 to 180 ° C and a glass transition temperature of 10 ° C or lower.   The easily peelable film according to claim 1 or 2, wherein the wax (C) contained in the polyester resin composition is polyethylene having a weight average molecular weight of 500 to 5,000. The easily peelable film as described in any one of Claims 1-3 which has the sealing layer which consists of a polyester-type resin composition, and the adjacent layer which consists of an olefin resin adjacent to this sealing layer. The easily peelable film according to claim 4 , wherein the thickness of the seal layer in the total thickness of the easily peelable film is 3 to 70%. The lid | cover material using the easily peelable film as described in any one of Claims 1-5 .