JP2005169825A - Polyester laminate and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester laminate improved in manual cutting properties and suitably used in an easily opening packaging material, an easily thrusting packaging material, an easily cut pressure-sensitive adhesive tape or the like, and its manufacturing method. <P>SOLUTION: The polyester laminate has a layer A with a thickness of 6.5-100 μm comprising a polyester resin and is characterized in that the heating elongation of the polyester constituting the layer A at the melting point under a load of 3 g/cm is 5% or below and K represented by the formula (1):K=elongation [%] at break × load [N/10 mm width] at break is 1-3,000. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a laminated structure using a polyester such as polylactic acid, and has excellent easy-cutting properties, design properties, and processability. The present invention relates to a laminate suitable for uses such as easy-openability and easy-piercing properties such as a straw, and a laminated sheet for packaging and a hand-cut adhesive tape, and a method for producing the same.

  In recent packaging materials, various proposals have been made focusing on easy-openability.

  For example, Patent Document 1 and Patent Document 2 disclose an easy-cut polyester film obtained by laminating a high-melting polyester and a low-melting polyester in a film-forming process and heat-treating at or above the melting point of the low-melting polyester. .

  Patent Document 3 proposes an easy-cut polyester film obtained by chemically modifying an aliphatic polyester film by irradiating it with ultraviolet rays or electron beams.

Patent Documents 4 and 5 show examples of easy-cut laminates in which paper or aluminum is combined with a polyester film and an adhesive layer is further provided.
JP-A-5-104618 (Example 1) JP 2001-191407 A (Example 5) JP 2003-261696 A (Examples 1 to 5) JP 2002-87459 A (Examples 1 to 3) Japanese Unexamined Patent Publication No. 2002-104496 (Example 1)

  However, the prior art has a problem that it is extremely difficult to achieve both easy cutability and processability as described below, and improvement has been desired.

  If the film shown by patent documents 1-3 laminates an adhesion layer etc., it will become a layered product with easy cut nature, but since easy cut nature is given to the film before processing, at the time of lamination processing It is not satisfactory because it is inferior in workability, such as breakage and scratches during handling.

  Further, in the examples of Patent Documents 4 and 5, since the film thickness to be used is thin, wrinkles are likely to occur during handling and processing, which is not satisfactory. In addition, if the film thickness is thin, the design properties are inferior, and there is a disadvantage that an inexpensive impression that lacks profound feeling due to appearance and touch is obtained.

  The object of the present invention is to eliminate the above-mentioned problems of the prior art, and it is suitable as a laminate that achieves both easy-cutting and processing suitability, particularly as a packaging material for foods, pharmaceuticals, etc. that are easy to open, and as an adhesive tape. It is providing the polyester laminated body used and its manufacturing method.

  In order to solve the above problems, the present invention has the following configuration. That is, the polyester laminate of the present invention has an A layer made of a polyester resin and having a thickness of 6.5 to 100 μm or more, and the heating elongation under a load of 3 g / cm at the melting point of the polyester constituting the A layer is 5% or less. And K represented by the following (formula 1) is in the range of 1 to 3000.

K = Elongation at break [%] × Load at break [N / 10 mm width] (Formula 1)
In addition, the method for producing a polyester laminate of the present invention softens a single-layer or multi-layer polyester film having at least an end tear resistance of 18 to 500 N with the melting point (Tm ₁ ) of the polyester having the highest melting point constituting the polyester film. And a heat treatment at a temperature of (Tm ₁ -15) ° C. or higher.

  The polyester laminate of the present invention is excellent in easy cutting properties and is also excellent in processability during production. In particular, it can be suitably used as a packaging material for foods, pharmaceuticals, etc. that can be easily opened when taking out the contents, a packaging material with excellent piercing properties such as a straw, and an adhesive tape. Moreover, according to the manufacturing method of the polyester laminated body of this invention, the polyester laminated body excellent in easy cut property can be obtained.

  The polyester laminate of the present invention has at least one A layer made of polyester.

  Here, the polyester in the present invention is a general term for high molecular weight substances constituted by ester bonds, and examples thereof include polycondensation polymers of polyhydroxycarboxylic acid, dicarboxylic acid and glycol.

  Typical examples of polyhydroxycarboxylic acid include polymers obtained from lactic acid, glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 3-hydroxyvaleric acid, 4-hydroxyvaleric acid, 6-bidoxycaproic acid, and the like. It is done. These polyhydroxycarboxylic acids may be a single hydroxycarboxylic acid or a copolymer composed of a plurality of hydroxycarboxylic acids.

  The polycondensation polymer of dicarboxylic acid and glycol is a high molecular weight product obtained by polycondensation of a dicarboxylic acid component and a glycol component as exemplified below.

  Examples of dicarboxylic acid components include terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, diphenyldicarboxylic acid, diphenylsulfone dicarboxylic acid, diphenoxyethanedicarboxylic acid, 5-sodium sulfoisophthalic acid, phthalic acid and other aromatic dicarboxylic acids, Acid, succinic acid, adipic acid, sebacic acid, dimer acid, maleic acid, fumaric acid and other aliphatic dicarboxylic acids, cyclohexyne dicarboxylic acid and other alicyclic dicarboxylic acids, p-oxybenzoic acid and other oxycarboxylic acids and the like Can be mentioned. On the other hand, examples of the glycol component include aliphatic glycols such as ethylene glycol, propanediol, butanediol, pentanediol, hexanediol, and neopentylglycol, alicyclic glycols such as cyclohexanedimethanol, and aromatics such as bisphenol A and bisphenol S. Group glycol, diethylene glycol and the like. These dicarboxylic acid components and glycol components may be used in combination of two or more.

  Furthermore, as long as the effects of the present invention are not impaired, the polyester used in the present invention can be used by copolymerizing a polyfunctional compound such as trimellitic acid, trimesic acid, or trimethylolpropane. Moreover, the said polyester may be used independently and may blend and use 2 or more types.

  Furthermore, the polyester film used in the present invention may be a single layer or a laminated layer. Here, the laminated polyester film is a film obtained by laminating polyester with a plurality of extruders.

  Among these, as a preferable polyester resin used for the A layer in the present invention, a polyester resin mainly composed of an aliphatic component is preferable from the viewpoint of easy cutability, and a polylactic acid resin from the viewpoint of heat resistance and stability over time. Is particularly preferred.

  The preferred ratio of L-lactic acid: D-lactic acid in the polylactic acid resin used is in the range of 100: 0 to 60:40, more preferably in the range of 99: 1 to 75:25. Within the said range, since the heat resistance becomes high if the ratio of L lactic acid becomes high, it is preferable. Moreover, if the ratio of D lactic acid becomes high, workability will become easy. If the ratio of D lactic acid is not less than the above range, the heat resistance is remarkably lowered, which is not preferable.

  The weight average molecular weight of the polylactic acid resin is preferably in the range of 60,000 to 500,000, more preferably 70,000 to 300,000, particularly preferably 80,000 to 180,000. If the weight average molecular weight is less than the above range, it is not preferable because physical properties such as aging stability and heat resistance and processing properties such as film forming stability are inferior. On the other hand, exceeding the above-mentioned range is not preferable because it leads to deterioration of easy-cutting property, and the melt viscosity becomes high, and filtration with a filter and removal of foreign matters in the polymer become difficult, resulting in deterioration of production efficiency.

  Moreover, in this invention, it is preferable that melting | fusing point of polyester is the range of 120-300 degreeC from the surface of heat resistance and an easy cut property. More preferably, it is 130-230 degreeC, Most preferably, it is 140-180 degreeC. If it is less than the above range, the heat resistance is insufficient, which may cause problems in processing and actual use such as lamination. Also, if the above range is exceeded, when heat treatment is performed to improve easy cutting properties, the amount of heat required increases, so the productivity deteriorates, and further, other layers (other than layer A) may be damaged. It is not preferable.

  Here, the melting point of polyester is a crystal melting peak temperature measured by DSC. The polyester of layer A used in the polyester laminate of the present invention is particularly preferably a crystalline polyester in terms of heat resistance. When the polyester is amorphous, the value of the softening point temperature can be regarded as the melting point. In addition, when measuring the melting point of layer A in the laminate, it is possible to measure with DSC after separating each layer, or to cut the end face of the polyester laminate and measure with a micro thermal analyzer (μTA). It is.

  The polyester and polyester film used in the present invention are preferably in the range of 20% by weight or less, particularly preferably in the range of 5% by weight or less, plasticizer, lubricant, inorganic particles, organic particles, antioxidant, antistatic agent. In addition, various additives such as ultraviolet absorbers and anti-coloring agents and modifiers, as well as known polymers such as aliphatic polyesters, aromatic polyesters, and polyolefins can be contained.

  In order to impart easy lubricity to the film and improve handling during processing, the polyester film of the present invention preferably contains inorganic particles, organic particles, organic lubricants, and the like.

  Examples of inorganic particles include clay, mica, titanium oxide, calcium carbonate, calcium phosphate, kaolin, talc, alumina, zirconia, spinel, wet or dry silica, and organic particles include acrylic polymers and polystyrene. Organic particles as a component can be mentioned. Among these, inorganic particles such as silica and alumina can be preferably used from the viewpoint of dispersibility.

  Although the particle diameter of these inorganic particles and organic particles is not particularly limited, it is preferably 0.01 to 5 μm, more preferably 0.1 to 3 μm. Moreover, the addition amount to the film of an inorganic particle and an organic particle is the range of 0.001-30 weight%, More preferably, it is the range of 0.01-1 weight%.

  Preferred organic lubricants include oleic acid amide, stearic acid amide, erucic acid amide, behenic acid amide, N-oleyl palmitoamide, N-stearyl erucamide, ethylene bis stearic acid amide, ethylene bis oleic acid amide and the like. Amide organic lubricants, methyl laurate, methyl myristate, methyl palmitate, methyl stearate, methyl oleate, methyl erucate, methyl behenate, butyl laurate, butyl stearate, isopropyl myristate, palmitate Such as isopropyl acid, octyl palmitate, octyl palm fatty acid ester, octyl stearate, lauryl laurate, stearyl long stearate, higher alcohol ester of long chain fatty acid, behenine behenate, cetyl myristate, etc. Ester-based organic lubricants, and also fatty acid salts such as zinc stearate, calcium stearate, magnesium stearate, aluminum stearate, barium stearate, lithium stearate, lead stearate, sodium oleate, barium laurate, zinc laurate, Examples thereof include silicon compounds, carnauba wax, and candelilla wax. Of these, amide-based lubricants can be suitably used from the viewpoints of excellent slipperiness and bleed-out resistance.

  The amount of organic lubricant added to the film is preferably in the range of 0.01 to 0.5% by weight, more preferably 0.03 to 0.5% by weight, and particularly preferably 0.1 to 0.4%. It is in the range of wt%.

  The polyester film in the present invention preferably has high transparency and preferably has a haze of 10% or less. Particularly preferably, it is 3% or less. When the transparency is good, the pattern is clear when printing from the back side of the film, and it can be preferably used in applications where transparency is required for content confirmation. In order to set the haze within the above range, it is preferable to suppress the amount of additives, modifiers and incompatible different polymers added to the film having a size of 0.1 μm or larger or a dispersed diameter. Moreover, it is preferable that the addition amount shall be 1 weight% or less with respect to a polylactic acid-type resin. The lower limit is not particularly limited, but is about 0.001% by weight.

  The thickness of the A layer of the present invention needs to be 6.5 to 100 μm. Moreover, the thickness of A layer and a polyester film becomes like this. More preferably, it is 10-50 micrometers, Most preferably, it is 12-25 micrometers. If the thickness is less than the above range, wrinkles are likely to occur during processing due to the thin film, and the laminated product is inferior in beauty and design, and it is preferable because it has a cheap impression that lacks profound feeling in appearance and touch. Absent. On the other hand, if the thickness exceeds the above-mentioned range, it is inferior in terms of easy cutability, which is an object of the present invention, and further, it leads to an increase in cost of the polyester laminate of the present invention.

  It is preferable that the end tear resistance of the polyester film used when manufacturing the laminated body of this invention is 18-500N. More preferably, it is the range of 25-300N, Most preferably, it is the range of 100-200N. The end tear resistance is measured using a test fixture B with a sample width of 20 mm in accordance with JIS C2151. The breaking strength of the polyester film used in the present invention is preferably in the range of 25 to 250 MPa, particularly preferably in the range of 50 to 200 MPa. If both the end resistance and the breaking strength are less than the above ranges, the deterioration of workability is remarkable such as causing breakage during processing, and exceeding the above ranges is not preferable because it leads to a decrease in easy cutting properties. .

  The breaking elongation of the polyester film used in the present invention is preferably in the range of 50 to 300%, more preferably 80 to 200%, and particularly preferably in the range of 100 to 150%. If the elongation at break is smaller than the above range, it becomes a problem in terms of protecting the contents, especially when used as a packaging material, or when it is used as a material with a deposited layer or aluminum foil layer, it may cause a decrease in gas barrier properties. This is not preferable. Moreover, when exceeding the said range, since it may become a cause which deteriorates an easy-open characteristic, it is unpreferable.

  Here, the physical property values of the above-mentioned end tear resistance, breaking strength, and breaking elongation of the polyester film are all applied to the longitudinal direction (MD) and the width direction (TD) of the film. For a film in which MD and TD are unclear, the present invention is applied to any one direction on the film surface and two directions perpendicular thereto.

  There are no particular restrictions on the means for bringing the end tear resistance, breaking strength, and breaking elongation of the polyester film within these ranges. For example, additives such as lubricants added to polylactic acid resins, modifiers, and different polymers. The content of the glass is reduced as much as possible and extreme orientation due to stretching is suppressed. Specifically, the stretching temperature during film formation ranges from (Tg (glass transition temperature [° C.]) + 5) to (Tg + 30) ° C. In addition, the stretching magnification may be set to a range of 4 to 16 times as the surface magnification (vertical magnification × horizontal magnification).

  Moreover, it is preferable that the thermal shrinkage rate at the time of 120 degreeC x 30 minute heating of the polyester film of this invention is the range of -5 to 5% in both the longitudinal direction (MD) of a film, and the width direction (TD). Preferably it is -1 to 3% of range. If the heat shrinkage rate is large, the film is greatly shrunk during film processing, which is not preferable because it causes printing distortion and wrinkles. On the other hand, if it is smaller than this range, it means that the film is stretched at the time of heat processing, and it is easily deformed by the winding tension, making winding difficult.

  The method for setting the thermal shrinkage rate of the polyester film in the above range is not particularly limited. For example, while the film is relaxed in advance by about 0.5 to 10% in the film production process, for example, a relatively low temperature of about 120 to 160 ° C. Examples thereof include a method of heat treatment (heat setting) at a high temperature and a method of heat treatment at a temperature of about 120 to 160 ° C. while relaxing a film once wound in a heating oven.

  The polyester film used in the present invention is preferably a uniaxially oriented film or a biaxially oriented film in order to make the film thickness uniform and improve workability and impact resistance. Although the manufacturing method of these oriented films is not particularly limited, an example using a polylactic acid resin is shown below.

  Polylactic acid resin and lubricant master pellet (polylactic acid resin containing a high concentration (about 2 to 50% by weight) of a lubricant such as silicon oxide in advance using a biaxial extruder) and a lubricant addition concentration of 0.01 to It is diluted and mixed so as to be about 0.5% by weight, dried at an appropriate temperature (for example, a temperature of about 60 to 140 ° C.) and sufficiently removed moisture (moisture content of 300 ppm or less, preferably 100 ppm or less), and then extruded. The polymer is melted in a suitable condition at about 180 to 250 ° C. to form a polymer stream. The molten polymer is passed through a filter having a filtration accuracy of about 5 to 50 μm, and the polymer is filtered to remove coarse foreign matters. The polymer after filtration is extruded into a sheet form from a slit-shaped base, and is brought into close contact with a casting drum whose temperature is controlled to about 10 to 50 ° C. by a technique such as an electrostatic application method to cool and solidify to produce an unstretched film. The film is continuously heated and stretched about 2 to 5 times in the longitudinal direction, and then introduced into the tenter and heated and stretched 2 to 6 times in the lateral direction while being held by a clip. An oriented film is obtained by heat treatment at a temperature.

  In the laminate of the present invention, another layer can be provided according to the purpose. Examples thereof include an adhesive layer, a metal foil layer, a vapor deposition film layer, a printing ink layer, an easy adhesion coating layer, an antistatic coating layer, an anchor coating layer for improving adhesion between layers, and a layer made of paper.

  These layers are arranged by a method of laminating a film-like adhesive layer by dry lamination using an adhesive or the like, a method of extrusion lamination in which an adhesive resin is directly melt extruded and laminated on a sheet, and a liquid thermal adhesive coating. A method of applying (coating) an agent or a pressure-sensitive adhesive is preferred, but it is not particularly limited as long as it does not impair the object of the present invention. The vapor deposition film layer and the printing ink layer can be directly arranged using a vapor deposition machine or a printing machine.

  Moreover, in order to improve the easy-cut property which is the subject of this invention, it is effective to improve the adhesiveness of each interface of a laminated body, and when producing a laminated body for each layer by methods, such as the said laminate, The surfaces to be joined are preferably subjected to corona treatment, anchor coating, and easy adhesion coating in advance. These surface treatments can be performed in combination.

  As the adhesive layer (B layer), a heat-adhesive resin, a pressure-sensitive adhesive, or the like can be used. Examples of the heat-adhesive resin include various sealant resins such as low density polyethylene, linear low density polyethylene, metallocene polyethylene, ionomer polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid. Examples thereof include a copolymer and an ethylene-methacrylic acid copolymer. Of these, low density polyethylene that is thermally stable and has few additives, and linear low density polyethylene having flexibility can be preferably used.

  Examples of the pressure sensitive adhesive include, but are not particularly limited to, a silicon pressure sensitive adhesive, an acrylic pressure sensitive adhesive, a rubber pressure sensitive adhesive, and a vinyl chloride pressure sensitive adhesive.

  In addition, it is possible to use a biodegradable resin as the base resin in the B layer, for example, polybutylene succinate, polobutylene succinate adipate, polyhydroxybutyrate, polylactic acid, or starch-derived modification Examples thereof include polymer resins, shellac resins, and derivatives of these resins.

  In addition, the thickness of the B layer can be arbitrarily selected in consideration of easy cutability and adhesiveness required by the application, but is usually in the range of 0.001 to 50 μm.

  For example, it is preferable to dispose a metal foil layer (C layer) or a vapor deposition film layer (D layer) in applications that require high gas barrier properties. In particular, a metal foil can be preferably used when dead hold property is required. Examples of the material constituting the metal foil and / or the vapor deposition film include aluminum, copper, silver, gold, tin, cobalt, nickel, chromium, etc., and the vapor deposition film uses an oxide compound such as aluminum oxide or silicon oxide. It is also possible.

  In addition, when placing a layer (E layer) made of paper such as kraft paper, fine paper, pure white paper, paper, glassine, rayon paper, synthetic fiber paper, etc., dead hold property, light weight, etc. can be added, and hand cutting properties are also particularly good. Therefore, it can be used as an easy-open packaging material.

  A preferred configuration example is given below. A / C / B configuration, A / E / C / B configuration, A / C / E / B configuration, A / D /, which has a dead hold property in which the opening is folded in addition to gas barrier properties A configuration such as E / B and a configuration such as A / E / B having a dead hold property are preferable. Here, each layer is a layer made of A: polyester layer, B: adhesive layer, C: metal foil layer, D: vapor deposition film layer, E: paper as described above. Moreover, you may have another layer between each layer in the range which does not inhibit the effect of this invention.

  The thickness of each of the above layers can be arbitrarily selected as long as the object of the present invention is not impaired. For example, the thickness of the aluminum foil layer is about 3 to 200 μm, and the thickness of the layer made of paper is about 5 to 1000 μm.

  The polyester laminate of the present invention needs to have an elongation of 5% or less under a load of 3 g / cm (3 g per 1 cm width) at the melting point of the polyester constituting the A layer. Here, the heating elongation is a change in dimensions when a 3 g weight is hung on a film cut into a 1 cm wide strip and heated in a hot air oven heated to a predetermined temperature for about 5 to 30 minutes. . It can also be obtained from dimensional changes with respect to temperature measured in a constant load mode such as a thermomechanical analyzer (TMA). The heating elongation is more preferably 3% or less, particularly preferably 2% or less. The measurement direction is relative to the longitudinal direction (MD) of the laminate. The heating elongation is more preferably 3% or less, and particularly preferably 2% or less. The closer the heating elongation is to 0%, the better the processing stability of the laminate with respect to the heat treatment. Sometimes the laminate tends to stretch, which is not preferable.

  In the polyester laminate of the present invention, K represented by the following (Formula 1) is required to be in the range of 1 to 3000 in order to achieve easy cutting, which is the object of the present invention.

K = Elongation at break [%] × Load at break [N / 10 mm width] (Formula 1)
In terms of both easy cutting properties and processability, the range is more preferably 50 to 2500, and particularly preferably 100 to 2000.

  Here, K shown in Equation 1 is a parameter indicating easy cutability, and is a value calculated by the product of the breaking elongation measured by a tensile tester and the load at the breaking point, and is the energy required for breaking. It is a numerical value. The inventor cuts the end portion of the laminate without a notch (corresponding to the phenomenon of fracture in the tensile test), and K represented by Formula 1 and the easy-cut property in the sensory test correspond well. I found out. Here, the easy cutability in the sensory test is determined by the rate of cut (%) after testing 30 times or more whether or not it is possible to tear with a finger in a direction perpendicular to the cut side of the laminate sample. Is.

  The elongation at break and load at break are preferably 23 ° C. under the conditions of the initial length of the measurement sample (distance between chucks): 5 mm, width: 10 mm, and pulling speed: 5 to 100 mm / min in order to suppress variation in measurement. It is a numerical value measured at. The elongation at break and load at break are applied to the longitudinal direction (MD) and the width direction (TD) of the laminate. For a laminated body in which MD and TD are unclear, the present invention is applied to any one direction on the laminated body surface and two directions perpendicular thereto.

  Furthermore, the breaking elongation of the polyester laminate of the present invention is preferably 100% or less, more preferably 1 to 80%, and particularly preferably 5 to 50%. Exceeding this range is not preferable in terms of easy cutting. Moreover, if it is less than this range, the intensity | strength of a laminated body may become inadequate and is unpreferable.

There is no particular limitation on the method for setting the K and the elongation at break in the above-mentioned range, but a method of forming the A layer with a polyester film having a relatively low breaking strength and breaking elongation. Or after laminating a polyester film with mechanical properties such as mechanical properties that are easy to work with a support that does not soften at the melting point (Tm ₁ [° C]) of the polyester of the highest melting point constituting the polyester film, and further (Tm ₁ -15) technique such as heat treatment is performed at ℃ temperatures above the like. In particular, the latter method in which heat treatment is performed after lamination is preferable in terms of processability and handling.

Further, a more preferable heat treatment temperature at this time is (Tm ₁ -5) ° C. or more, particularly preferably (Tm ₁ ) ° C. or more, and (Tm ₁ +5) for improving the flatness of the processed product. ) C or higher. The upper limit of the heat treatment temperature can be arbitrarily set within a range that does not interfere with the processing stability, but the upper limit is usually about 600 ° C.

  At this time, the heat treatment method is not particularly limited, but the polyester laminated sheet is passed through a heating oven and heated with hot air or the like, while the opposite surface of the polyester layer is brought into close contact with the cooling drum and conveyed. A method of heating a layer with a radiation heater, a method of heating with a radiation heater in the middle of a transport roll, a method of heating a sheet directly with a hot plate, a method of passing through a heating bath and heating, a steam directly or indirectly The method of spraying heating etc. is mentioned. In particular, a method using a heating oven and a method using a radiation heater are preferable because relatively easy cutting properties can be expressed relatively efficiently.

  The heat treatment time at this time can be appropriately adjusted according to the thermal characteristics of the polyester used, the heating temperature, and the heat treatment method to achieve the desired easy cutting properties, but is relatively short if it is 1 minute or less. Since it is time, it is preferable from the viewpoint of production efficiency, more preferably 30 seconds or less, and particularly preferably 15 seconds or less. The lower limit is preferably a heat treatment time of 0.01 seconds or more in order to achieve sufficient easy cutting properties.

  These heat treatments are preferably carried out after laminating a polyester film and a support that does not soften at the melting point of the polyester. However, the heat treatment may be carried out in a series of steps following the lamination, and once laminated, it is once rolled. It may be wound up and then unwound again for heat treatment.

  When two or more types of layers are stacked, heat treatment may be performed after all layers are stacked, or heat treatment may be performed after stacking a layer to be a support, and another layer may be stacked. Good. Furthermore, it is also possible to heat-treat in the shape of the final processed product, such as a bag shape for packaging materials. In particular, in the case of laminating an adhesive layer or a thermally unstable layer, it is preferable to heat-treat after laminating a layer to be a support, and then laminate an adhesive layer or a thermally unstable layer.

  Examples of the support that does not soften at the melting point of polyester include metal foil, paper, and thermoplastic resin. Examples of the metal foil include those described above as the C layer, and examples of the paper include those described above as the E layer. Further, the thermoplastic resin is preferably a resin having a melting point 30 ° C. or higher than the polyester of the A layer, more preferably 40 ° C. or higher, and particularly preferably 50 ° C. or higher. The upper limit of the melting point of the thermoplastic resin is not particularly limited as long as it does not interfere with easy cutability, processability, appearance beauty, and the like, but those having a temperature of 300 ° C. or lower can be preferably used. As a specific example of the thermoplastic resin used for the support, a polyester-based resin can be preferably exemplified, and in particular, polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate, and copolymers thereof can be exemplified. Examples of the copolymer component include a dicarboxylic acid component and a glycol component used in the polyester-based resin used in the above-described A layer. Particularly, a linear aliphatic copolymer component is mainly used to improve easy cutting properties. . These thermoplastic resins are preferably aligned in advance by uniaxial stretching and biaxial stretching.

  The polyester laminate of the present invention is suitable as a packaging material for articles, foods, and pharmaceuticals such as solids, liquids, and viscous materials typified by pillows, side seals, three-way, four-way seals, and the like. Even if there is no notch), it can be easily torn by hand from any place, and thus is particularly suitable as a packaging material that can be easily opened when taking out the contents.

Hereinafter, the present invention will be further described by examples.
[Measurement method of characteristics]
(1) Melting point A 5 mg measurement sample (polyester film before processing into a laminate) was collected and measured with a differential scanning calorimeter (DSC type 2 manufactured by Perkin Elmer) at a heating rate of 10 ° C./min. The peak temperature was taken as the melting point.

(2) Breaking strength / breaking elongation A sample was cut into a width of 10 mm and a length of 150 mm, and a tensile test was conducted under the conditions of an initial length (distance between chucks) of 50 mm, a tensile speed of 300 mm / min, and 23 ° C., and a breaking strength (MPa). The elongation at break (%) was measured.

  In addition, these measured values are based on the average value performed about the longitudinal direction 5 points | pieces and the width direction 5 points | pieces of the film.

(3) End tear resistance According to JISC2151, measurement was performed under the conditions of a sample width of 20 mm, a test fitting B (V-shaped cut type), a pulling speed of 200 mm / min, and 23 ° C.

(4) Heat elongation rate Five samples were prepared by cutting the laminate into a strip shape having a width of 20 cm in the longitudinal direction and a width of 1 cm in the width direction, and a reference line having an interval of 10 cm was drawn in the central portion. A weight was applied by attaching a 3 g weight to the bottom of the cut sample with double-sided tape. The sample was heat-treated for 10 minutes in a hot air oven heated to the melting point of the polyester constituting the A layer, the dimensional change of the reference line interval before and after that was measured, and the heating elongation (% ).

(5) K value (easy-cutting parameter), laminate elongation 10 mm wide, 150 mm long laminate sample cut out, tensioned at initial length (chuck distance) 5 mm, tensile speed 50 mm / min, 23 ° C. Tests were performed and the elongation at break (%) and load at break (N) were recorded. In addition, a measured value is each average value of 10 points | pieces of the longitudinal direction (MD) and width direction (MD) of a laminated body. Further, the K value was calculated by the following (formula 1).

K = Elongation at break [%] × Load at break [N / 10 mm width] (Formula 1)
Further, the elongation at break obtained by the above measurement was defined as the elongation (%) of the laminate.

(6) Processing suitability The state of tearing and wrinkling in the processing step of the laminate was monitored, and the determination was made according to the following criteria according to the state.

  ○: No tearing or wrinkle is generated, and the processing state is good (pass).

  Δ: Breaking and wrinkling are observed, but processing is possible (pass).

  X: Processing is very difficult (failed).

(7) Easy cutability The MD sample (FIG. 1) which cut out the laminated body into the size of longitudinal direction (MD): 5cm x width direction (TD): 30cm, and the size of a laminated body with TD: 5cmxMD: 30cm Five TD samples (FIG. 2) cut out in advance were prepared. About each, it cut | disconnected with the finger | toe vertically from the edge of the long side. At the time of cutting, the sample was held with the first and second fingers of both hands, and was torn off at a substantially right angle with respect to the thickness direction at the position where the fingers of both hands were in contact. While maintaining the cutting start point at an interval of 1 cm or more, it was tested whether or not cutting was possible 20 times / sheet × 5 sheets: 100 times in total. The percentage (%) that can be cut with respect to the MD sample and the TD sample was recorded, and further judged according to the following criteria.

  ○: 90% or more (pass).

  (Triangle | delta): 60-90% (pass).

  X: Less than 60% (failed).

  In addition, the easy-cut property of the structure of cellophane / polyethylene / aluminum / polyethylene shown in the reference example is a determination of MD: Δ (76%) and TD: Δ (74%).

[Creation of polyester film used for layer A]
(Film name: PLA-A, thickness: 15 μm) Polylactic acid A (weight average molecular weight of about 150,000, L-lactic acid component amount 98.5%, D-lactic acid component amount 1.5%, melting point 169 ° C.), and poly Lactic acid B (silica particles having an average particle diameter of 1.6 μm with respect to polylactic acid A (Mizukasil P-527 manufactured by Mizusawa Chemical Industry Co., Ltd.) at 210 ° C. using a twin screw extruder at a silica concentration of 5% by weight) Were mixed at a weight ratio of polylactic acid A: polylactic acid B = 99: 1, and dried under vacuum conditions of 120 ° C. and 2 KPa or less for 5 hours.

  The dried resin was supplied to a single screw extruder having a screw diameter of 50 mm and melted at an extruder cylinder temperature of 230 ° C. The molten polymer was passed through a sintered disk filter having a filtration accuracy of 20 μm, subsequently extruded into a film at a base temperature of 220 ° C., and casted electrostatically onto a mirror drum cooled to 30 ° C. to produce an unstretched film. Continuously stretched 3 times in the longitudinal direction between heating rolls at 85 ° C, and then the film edge was held by a clip and guided into the tenter, and stretched 3.3 times in the lateral direction while heating at a temperature of 75 ° C. Then, heat treatment was performed at 140 ° C. for 12 seconds while relaxing 2% in the width direction to obtain a polylactic acid film having a thickness of 15 μm. The obtained polylactic acid film was subjected to corona treatment on one side. Table 1 shows the characteristics of the obtained film. It is a film that is sufficiently high in strength, elongation, and end tear resistance, and excellent in handleability.

  (Film name: PLA-B, thickness: 25 μm) A polylactic acid film having a thickness of 25 μm was obtained in the same manner as in Example 1. As in Example 1, the obtained film was sufficiently high in strength, elongation, and end tear resistance, and excellent in handleability.

  (Film name: PLA-C, thickness: 10 μm) A polylactic acid film having a thickness of 10 μm was obtained in the same manner as in Example 1. Although the obtained film is slightly inferior to end tear resistance as compared with Example 1, it is a film having high strength and elongation and good handleability.

  (Film name: PLA-D, thickness: 5.5 μm) A polylactic acid film having a thickness of 5.5 μm was obtained in the same manner as in Example 1. The obtained film is a film having low end resistance.

  (Film name: PLA-Z, thickness: 25 μm) Coextrusion polylactic acid based on two types and three layers of high melting point layer / low melting point layer / high melting point layer (lamination ratio: 1: 4: 1) by the following procedure A film (PLA-Z) was produced.

  First, as a polylactic acid resin constituting the high melting point layer, the polylactic acid A: polylactic acid B used in Example 1 was mixed at a weight ratio of 99: 1, and the mixture was mixed under a vacuum condition of 120 ° C. and 2 KPa or less for 5 hours. Dried. In addition, polylactic acid C (weight average molecular weight: about 150,000, L-lactic acid component amount: 85%, D-lactic acid component amount: 15%), melting point: 149 ° C.) and polylactic acid D as the polylactic acid resin constituting the low melting point layer (Polylactic acid C mixed with silica particles having an average particle diameter of 1.6 μm <Mizusaka Chemical Co., Ltd. Mizukasil P-527> mixed at 210 ° C. using a twin screw extruder at a silica concentration of 5% by weight) The mixture was mixed at a weight ratio of lactic acid C: polylactic acid D = 99: 1 and dried under vacuum conditions of 100 ° C. and 2 KPa or less for 7 hours.

  The resin constituting the low melting point layer after drying was supplied to a single screw extruder having a screw diameter of 40 mm and melted at an extruder cylinder temperature of 200 ° C. Further, the resin constituting the high melting point layer was separately supplied to a single screw extruder having a screw system of 50 mm and melted at an extruder cylinder temperature of 230 ° C.

  The molten polymer is passed through sintered disk filters each having a filtration accuracy of 20 μm, and subsequently, the resin constituting the high melting point layer is formed from the three-layer multi-manifold base at 210 ° C. with the first and third layers (front and back layers). ), The resin constituting the low melting point layer is merged as the second layer (intermediate layer), extruded into a film shape at a base temperature of 210 ° C., and electrostatically cast on a drum cooled to 30 ° C. A stretched film was prepared. Subsequently, the film was continuously stretched 2.6 times in the longitudinal direction between heating rolls at 75 ° C., and then the film end was held by a clip and guided into the tenter, and 3.6 ° in the lateral direction while being heated at a temperature of 73 ° C. Double-stretched, heat-treated in a tenter at 150 ° C. for 12 seconds, and co-extruded poly (two types and three layers) of thickness 25 μm, high melting point layer / low melting point layer / high melting point layer (lamination ratio: 1: 4: 1) A lactic acid film was obtained. The obtained polylactic acid film was subjected to corona treatment on one side. The obtained film has a melting point of each layer, and in particular, the average value of the elongation at break is 79%, which is lower than the films of PLA-A to D.

  (Film name: PLA-UV, thickness: 25 μm) About PLA-B prepared by the above method, ultraviolet irradiation with a germicidal lamp (Toshiba germicidal lamp GL20-A) attached to an exposure device (JEA2SS: manufactured by JEOL Ltd.) The treatment device was subjected to ultraviolet irradiation treatment for 3 minutes. The properties of the film after the ultraviolet treatment are films having particularly low end resistance, low breaking strength, and low elongation at break.

  (Film name: PET, thickness 7.5 μm) In the polycondensation reaction of ethylene glycol and terephthalic acid, wet silica (0.08 wt%) was added to add polyethylene terephthalate (intrinsic viscosity 0.65 dl / g, melting point 256 ° C. ) Polymerized. The obtained polyester was vacuum dried at 180 ° C. under a vacuum of 2 KPa or less for 4 hours, then supplied to a melt extruder, extruded into a sheet form from a slit-shaped die, and adhered to a mirror drum at 25 ° C. by electrostatic application. Cooled and solidified to produce an unstretched sheet. The unstretched sheet was first stretched 3.6 times in the longitudinal direction with a roll heated to a temperature of 120 ° C., further stretched 3.5 times in the width direction at a stretching temperature of 127 ° C., and then at 220 ° C. A biaxially stretched polyester film having a thickness of 7.5 μm was obtained by 5% relaxation in the direction and heat treatment for 8 seconds. One side of the obtained film was subjected to corona discharge treatment. The resulting film has a very high breaking strength.

  Table 1 shows the characteristics of the polyester film used in the examples.

[Creation of polyester laminate]
(Example 1)
A polyethyleneimine anchor coat (Epomin P-1000 manufactured by Nippon Shokubai Co., Ltd.) is applied to the corona-treated surface of a polylactic acid film (PLA-A, 15 μm), and low-density polyethylene (Tosoh Corporation, Petrocene 213, melting point 105). ° C) was melt extruded and extruded and laminated in a PLA-A / polyethylene / aluminum configuration. Subsequently, low-density polyethylene (Tosoh Corp., Petrocene 213, melting point 105 ° C.) was extruded and laminated on the aluminum side to prepare a PLA-A / polyethylene / aluminum / polyethylene polyester laminate shown in Table 2. Furthermore, the obtained polyester laminated body was passed through a hot-air oven heated to 180 ° C. for 10 seconds and subjected to heat treatment. There were no wrinkles or breakage during processing, and the processing ability was excellent. The composition of the obtained polyester laminate is shown in Table 2, and the characteristics are shown in Table 3. It was excellent in easy-cut property and was particularly good as the polyester laminate of the present invention.

(Example 2)
Except for using a polylactic acid film (PLA-B, 25 μm) instead of PLA-A, the laminate was extruded and laminated in the same manner as in Example 1 except that it was composed of PLA-B / polyethylene / aluminum / polyethylene. A polyester laminate subjected to heat treatment at 180 ° C. for 10 seconds was prepared in the same manner. There were no wrinkles or breakage during processing, and the processing ability was excellent. Moreover, it was excellent also in easy-cut property.

(Example 3)
An adhesive (Dainippon Ink & Chemicals, Dick Dry LX-75A / KW-40) is applied to the corona-treated surface of a polylactic acid film (PLA-A, 15 μm), and 50 μm paper and dry laminate are applied. Then, a PLA-A / paper laminate was prepared. Subsequently, heat treatment was performed at 180 ° C. for 10 seconds in the same manner as in Example 1. Furthermore, an adhesive ((Dai Nippon Ink Chemical Co., Ltd., Dick Dry LX-75A / KW-40) is applied to the corona-treated surface side of the linear low density polyethylene film (Toray Synthetic Film, Type 4801, 30 μm). Then, the laminate was dry laminated with the paper side of the PLA-A / paper laminate to obtain a polyester laminate laminated in the configuration of PLA-A / paper / polyethylene. It was a particularly good polyester laminate.

Example 4
Except for using a polylactic acid film (PLA-C, 10 μm) instead of PLA-A, the laminate was extruded and laminated in the configuration of PLA-C / polyethylene / aluminum / polyethylene in the same manner as in Example 1 to obtain a polyester laminate. Obtained. In addition, the heat processing to the laminated body after lamination was not implemented. Although slight wrinkles were observed during extrusion laminating, there was no tear and good laminating suitability. In addition, the laminate was good in terms of easy cutability.

(Example 5)
The laminated body prepared in Example 4 was subjected to heat treatment at 180 ° C. for 10 seconds in the same manner as in Example 1. The obtained laminated body was excellent in easy-cut property as compared with the laminated body before heat treatment (Example 4).

(Example 6)
Instead of PLA-A, it was extruded and laminated in the configuration of PLA-Z / polyethylene / aluminum / polyethylene in the same manner as in Example 1 except that a polylactic acid film (PLA-Z, 25 μm) was used. Created. No heat treatment after lamination was performed. Although the occurrence of tearing was slightly observed during laminating, it was good for laminating. Moreover, the laminated body was a thing with easy cut property favorable.

(Example 7)
The laminate prepared in Example 6 was subjected to heat treatment at 180 ° C. for 10 seconds in the same manner as in Example 1. The obtained laminate was easier to cut than the laminate before heat treatment (Example 6).

(Comparative Example 1)
Extrusion lamination was carried out in the same manner as in Example 1 except that a polyethylene terephthalate film (PET, 7.5 μm) was used instead of PLA-A, in the configuration of PET / polyethylene / aluminum / polyethylene. No heat treatment after lamination was performed. Although there was no generation of wrinkles or tearing during laminating and good laminating suitability, it was inferior in easy-cut property.

(Comparative Example 2)
In the same manner as in Example 1, a laminate having a configuration of PLA-A / polyethylene / aluminum / polyethylene was prepared by extrusion lamination. The polyester laminate of Comparative Example 2 was obtained without performing the subsequent heat treatment. It was a laminate having a high breaking energy and poor cutability.

(Comparative Example 3)
Extrusion laminating was carried out in the configuration of PLA-D / polyethylene / aluminum / polyethylene in the same manner as in Example 1 except that a polylactic acid film (PLA-D, 5.5 μm) was used instead of PLA-A. However, since the process was unstable due to the breakage of the film and wrinkles were remarkable, it was not possible to collect an evaluation laminate.

(Comparative Example 4)
Extrusion laminating was performed in the same manner as in Example 1 except that a polylactic acid film (PLA-UV, 25 μm) was used instead of PLA-A, in the configuration of PLA-UV / polyethylene / aluminum / polyethylene. Since the process was very unstable due to the breakage of the film, it was not possible to collect an evaluable laminate.

(Comparative Example 5)
A polyethyleneimine anchor coat (Epomin P-1000 manufactured by Nippon Shokubai Co., Ltd.) is applied to the corona-treated surface of a polylactic acid film (PLA-A, 15 μm), and low-density polyethylene (Tosoh Corporation, Petrocene 213, melting point 105). ° C) was melt extruded and extruded and laminated with a PLA-A / polyethylene construction. When the obtained polyester laminate was passed through a hot air oven heated to 180 ° C., the film was broken and heat treatment could not be obtained. When the characteristics of the unheated polyester laminate were evaluated, they were very inferior in easy-cut property.

(Reference example)
A laminate having the structure shown in Table 2 was prepared in the same manner as in Example 4 except that the film to be used was changed from a polylactic acid film to cellophane (manufactured by Nimura Chemical Co., Ltd., Taiho ordinary cellophane, brand PL # 300). did. The laminating suitability was good, and the easy-cutting property was also good.

  Table 2 shows the configurations of the polyester laminates obtained in Examples 1 to 5 and Comparative Examples 1 to 5.

  Table 3 shows the properties of the polyester laminates obtained in Examples 1 to 5 and Comparative Examples 1 to 5.

  The polyester laminate of the present invention can be widely applied to applications requiring so-called “easy-cut” that can be easily cut by hand, such as easy-open packaging materials and adhesive tapes. .

  Moreover, according to the method for producing a polyester laminate of the present invention, it is possible to suppress the generation of tears and wrinkles during processing, and it is possible to obtain a polyester laminate having excellent easy-cut properties. .

Schematic diagram of MD sample used for easy-cutability test Schematic diagram of TD sample used for easy-cutability test

Explanation of symbols

1 Cutting direction 2 MD direction 3 TD direction

Claims (5)

It has an A layer of 6.5 to 100 μm in thickness consisting of a polyester resin, the heating elongation under a load of 3 g / cm at the melting point of the polyester constituting the A layer is 5% or less, and the following (formula 1) The polyester laminated body whose K represented by these is the range of 1-3000.
K = Elongation at break [%] × Load at break [N / 10 mm width] (Formula 1) The polyester laminate according to claim 1, wherein the elongation at break is 100% or less. The polyester laminated body according to claim 1 or 2 which has a layer which consists of metal foil or paper. The polyester laminate according to any one of claims 1 to 3, wherein the A layer comprises a polylactic acid resin. A single-layer or laminated polyester film having at least edge resistance of 18 to 500 N is laminated with a support that does not soften at the melting point (Tm ₁ [° C.) of the polyester of the highest melting point constituting the polyester film, and (Tm ₁ -15) process for producing a polyester laminate is subjected to heat treatment at ℃ or higher.

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