JP4916447B2 - Multilayer film with biodegradable sealant layer - Google Patents

Description

  The present invention relates to a multilayer film with a biodegradable sealant layer having excellent packaging machine suitability. In particular, the present invention relates to a multilayer film with a biodegradable sealant layer having excellent sliding properties and a low-temperature sealing function, and a method for producing the same. Furthermore, the present invention relates to a bag-like article and a cushioning material using the film.

  Synthetic polymer compounds have been widely used as plastics due to their excellent properties. However, the amount of waste is also increasing with the increase of the amount of use, and how to process this waste plastic becomes a big social problem. When incinerated, there is a problem that the amount of heat generated is large and the incinerator is likely to be damaged and harmful substances may be generated. There is also a problem that it remains in the environment indefinitely because it is difficult to decompose when it is landfilled. Furthermore, considering the cost of separation / collection and regeneration, it is difficult to solve the problem completely by recycling alone.

  With the growing interest in environmental issues, biodegradable plastics that decompose in the natural environment after disposal are required to reduce environmental burden and make society sustainable. It has become.

  On the other hand, one of the packaging forms of the plastic film is a bag-packed package, which includes a pillow package, an overlap package, a two-way / three-way / four-way sealed package, a liquid bag, a retort package, and the like. In recent years, the continuous packaging machines for performing such packaging have been developed at a higher speed, and accordingly, the required characteristics of the packaging film to be used have become severe.

  The main characteristics required for the film used in these continuous packaging machines are low temperature sealability and slipperiness. The low temperature sealing property is a sealing property that enables heat sealing at a lower temperature and consequently enables high speed packaging (bag making) of the film. The heat seal is to stack a plurality of films and heat and pressurize them using a heating bar, a heating plate, a heating roll, or the like to adhere the films. Therefore, a film having excellent low-temperature sealing properties can be bonded in a short time from a lower temperature to a wide temperature range, and has practically sufficient adhesive strength. Furthermore, in film applications having a sealing function for the purpose of sealing, storing and holding the contents of liquids and gases, in order to prevent leakage of the contents of liquids and gases from the sealing part In addition, sealing and airtightness of the seal part are one of the very important sealing functions.

  The slipperiness means a dynamic friction coefficient (μd) between the metal surface of the packaging machine and the film surface in the film packaging process. In particular, a film having an appropriate dynamic friction coefficient (μd) is required for use in a packaging machine having a half-fold function or a packaging machine that changes the film feeding direction. In particular, when the seal surface is in contact with the metal surface of the half-folding jig, the dynamic friction coefficient (μd) between the seal surface and the metal surface is important. In addition, higher packaging speeds have made the demands on films more stringent.

  Under such circumstances, Patent Document 1 discloses an aliphatic polyester synthesized from glycol and an aliphatic dibasic acid or an acid derivative thereof having a sealing function at a melting point of 70 ° C. to 200 ° C. Yes. Patent Document 2 discloses a biaxially stretched laminated film of substantially amorphous polylactic acid and an aliphatic polyester copolymer, and Patent Document 3 discloses a substantially amorphous polylactic acid and an aliphatic polyester copolymer. And an aliphatic-aromatic polyester copolymer composition are disclosed. These disclosed films are films having low-temperature sealing properties, but aliphatic polyesters having a low melting point such as a melting point of 70 ° C. to 120 ° C. have a problem particularly in terms of the stability of the dynamic friction coefficient (μd) over time. Had.

  In Patent Document 4, 3 to 70 parts by weight of a biodegradable aliphatic polyester having a glass transition point Tg of 0 ° C. or lower is blended with 100 parts by weight of a crystalline polylactic acid polymer, and at least uniaxially. A method is described in which the sliding property of the stretched polylactic acid film is enhanced by stretching in the direction and applying heat treatment. Patent Document 5 discloses a lactic acid polymer in which an aliphatic amide and an anti-blocking agent are added to the lactic acid polymer. Patent Document 6 discloses a polylactic acid film in which the static friction coefficient and surface roughness between one side of the film are in a specific range. Any of these disclosed polylactic acid-based films relates to the slipperiness of the film surface, but no film having both low-temperature sealing properties and slipperiness has been disclosed.

  Further, when a lubricant, particularly an organic lubricant, is used to control the slipperiness, the slipperiness depends on the amount of lubricant bleed out on the film surface. For this reason, in order to express slippery immediately after film formation, a film having a composition with a fast bleed-out speed of the lubricant has been demanded. Further, since the amount of lubricant present on the film surface is in an equilibrium state at the storage temperature, for example, when the film is stored at a high temperature, the lubricant once bleeded out is impregnated into the film again, and the slipperiness is deteriorated. Sometimes. For this reason, depending on the storage temperature and storage period, the slipping property of the film is lowered, which may cause troubles during packaging (bag making). For this reason, a film with a biodegradable sealant layer excellent in bag-making properties that can be applied to a high-speed packaging machine that always expresses a certain level of slipperiness immediately after film formation and within a period of use and has sufficient low-temperature sealing properties. Was demanded.

  As a pyro-type air cushioning material, Patent Document 7 discloses a plastic packaging cushion. The purpose of this publication is to form a low-cost cushioning material that can be obtained with a small amount of raw materials while the hollow units are connected and molded so that the units work as a unit. There is no disclosure about the slipperiness of the film that satisfies the suitability of the packaging machine (bag making machine), and nothing is disclosed about the material and the biodegradable polymer. Patent Document 8 discloses an airbag cushioning material sheet that is inflatable and includes a self-sealing valve. Nylon and polyethylene laminate films have been disclosed as heat-sealable, non-breathable, flexible and to some extent mechanical strength, but are biodegradable with specific slip properties and sealing functions An airbag cushioning material using a film is not disclosed.

Japanese Patent No. 2759596 JP 2004-306482 A JP 2004-244553 A JP 2004-10900 A JP-A-2005-146200 JP 2004-331860 A Japanese Utility Model Publication No.59-10274 JP-A-4-154570

  The present invention provides a multilayer film with a biodegradable sealant layer that expresses a specific dynamic friction coefficient (μd) immediately after film formation, has a small change in dynamic friction coefficient (μd) within the period of use, and can be sealed at low temperature. The purpose is to do. That is, an object of the present invention is to provide a multilayer film with a biodegradable sealant layer that enables smooth film feeding in a packaging (bag making) machine and has excellent suitability for a high-speed packaging machine. It is another object of the present invention to provide a biodegradable packaging film, a bag-like article, and an air cushioning material that have a sufficient sealing function and are excellent in holding contents.

As a result of intensive studies to solve the above problems, the present inventors have found that in a multilayer film with a biodegradable sealant layer, a low melting point aliphatic polyester resin (B), polylactic acid (A), and a lubricant ( By mixing D) at a specific ratio, a composition was found in which the bleedout speed of the lubricant was increased. As a result, an appropriate dynamic friction coefficient (μd) was developed immediately after film formation, enabling smooth film feeding and low temperature sealing in a packaging (bag making) machine. Furthermore, even when the film is stored at a high temperature, when the film is returned to room temperature (use environment temperature), the lubricant immediately bleeds out, and an appropriate dynamic friction coefficient (μd) can be expressed. As a result, a film having a stable dynamic friction coefficient (μd) and having high-speed packaging suitability was obtained immediately after film formation within a trial period, and the present invention was achieved. Furthermore, by using a specific seal strength and multilayer structure, a biodegradable bag-shaped article and an air cushioning material were found, and the present invention was completed.
That is, the present invention is as follows.
(1) A biodegradable multilayer film having a sealant layer on at least one surface, wherein the sealant layer has a polylactic acid resin (A) and a glass transition temperature Tg of 10 ° C. or lower and a melting point of 70 ° C. or higher and 120 ° C. It consists of the mixture of the following aliphatic polyester-type resin (B) and the lubricant (D) which is fatty acid amides, The mixing mass ratio of (A) and (B) is (A) / (B) = 55/45. 13/87, and (D) is 0.01 to 0.5 parts by mass with respect to a total amount of 100 parts by mass of (A) and (B), and the dynamic friction coefficient (μd) of the surface having the sealant layer ) Is a multilayer film with a biodegradable sealant layer of 0.15 or more and 0.5 or less.
(2) The polylactic acid resin (A) is a substantially non-crystalline polylactic acid resin having a molar ratio of L-lactic acid and D-lactic acid constituting the resin of 92/8 to 8/92. The multilayer film with a biodegradable sealant layer according to (1) above.
(3) The multilayer film with a biodegradable sealant layer according to (1) or (2) above, wherein the aliphatic polyester resin (B) has a melting point of 70 ° C. or higher and 85 ° C. or lower.
(4) The crystal nucleating agent (C) is further included, and the addition amount of the crystal nucleating agent (C) is 100 parts by mass with respect to the total amount of the polylactic acid resin (A) and the aliphatic polyester resin (B). The multilayer film with a biodegradable sealant layer according to the above (3), which is 0.5 parts by mass or more and 43 parts by mass or less.
(5) The crystal nucleating agent (C) is an aliphatic polyester (C2), and the melting point of the aliphatic polyester resin (C2) is higher than 85 ° C. and lower than 170 ° C. Multilayer film with biodegradable sealant layer.
(6) The multilayer film with a biodegradable sealant layer according to (5), wherein the aliphatic polyester resin (C2) has a molecular weight of 170,000 or less.
( 7 ) It consists of a polylactic acid resin having a molar ratio of L-lactic acid and D-lactic acid constituting the resin of 95/5 to 100/0 and a crystal nucleating agent, and has a differential scanning calorific value when the temperature is raised at 10 ° C./min. At least a heat-resistant layer having a melting point (Tm) determined by measurement of 140 ° C. to 170 ° C. and a relationship between heat of fusion (ΔHm) and crystallization heat (ΔHc) (ΔHm−ΔHc) of 15 J / g to 60 J / g The multilayer film with a biodegradable sealant layer according to any one of (1) to ( 6 ), including one layer.
( 8 ) Any of the above (1) to (7), wherein the resin constituting each layer is co-extruded and melt stretched to form a film in a molten state under the condition that the stretch ratio is 40 to 200 times in terms of area ratio. A method for producing a multilayer film with a biodegradable sealant layer according to claim 1.
( 9 ) A bag-shaped article using the biodegradable packaging film according to any one of (1) to (7).
( 10 ) An airbag cushioning material using the biodegradable packaging film according to any one of (1) to (7).

  The multilayer film with a biodegradable sealant layer of the present invention has a low-temperature sealing property and has little change with time in the dynamic friction coefficient (μd) immediately after film formation and within the period of use. Therefore, it is possible to smoothly feed a film in a packaging (bag making) machine, and there is an effect of expressing excellent suitability for a packaging (bag making) machine even in high-speed packaging. Moreover, in order to express sufficient sealing strength, there exists an effect which hold | maintains the content of a liquid or gas, without making it leak.

  The present invention will be specifically described below. The multilayer film with a sealant layer of the present invention comprises a base material layer and a sealant layer. The base material layer is a layer that imparts physical properties such as tensile properties, elastic modulus (rigidity), tear strength, puncture strength, and functional properties that are generally necessary for packaging films, and those layers. It consists of an adhesive layer for adhering the layers. Specific examples of functionality include barrier properties, heat resistance, light shielding properties, and chemical resistance.

  The sealant layer of the present invention has a mixing mass ratio of the polylactic acid resin (A) and the aliphatic polyester resin (B) having a glass transition temperature Tg of 10 ° C. or lower and a melting point of 70 ° C. or higher and 120 ° C. or lower (A ) / (B) = 55/45 to 13/87, and it is important that the mixed composition contains the lubricant (D). Although the mechanism by which the bleed-out speed of the lubricant is increased is not accurately grasped, the polylactic acid (A) that is incompatible with the aliphatic polyester resin (B) is blended inside the film. It is thought that a resin interface is formed and the bleedout speed of the lubricant is increased. For this reason, it is considered that the change with time of the dynamic friction coefficient (μd) during the period of use is also small. When the mixing mass ratio of the polylactic acid-based resin (A) is larger than (A) / (B) = 55/45, the polylactic acid-based resin forms a matrix. Proper seal strength is difficult to obtain. When the mixing mass ratio of the polylactic acid resin (A) is less than (A) / (B) = 13/87, there are few interfaces of the polylactic acid resin formed in the matrix of (B), and film formation It is difficult to develop slipperiness from the beginning. A more preferable mixing mass ratio is (A) / (B) = 55/45 to 15/85, further preferably (A) / (B) = 30/70 to 15/85, and still more preferably, (A) / (B) = 25/75 to 15/85.

  The polylactic acid resin (A) used in the present invention is an aliphatic polyester mainly composed of lactic acid, and is a lactic acid homopolymer and / or a copolymer containing 50% or more of lactic acid monomer units, It is a copolymer of lactic acid and a compound selected from the group consisting of other hydroxycarboxylic acids and / or lactones. As a monomer used as a copolymerization component with lactic acid, as hydroxycarboxylic acid, glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 3-hydroxyvaleric acid, 4-hydroxyvaleric acid, 6-hydroxycaproic acid Etc. Examples of the aliphatic cyclic ester include glycolide, lactide, β-propiolactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone, and lactones substituted with various groups such as a methyl group.

  In the present invention, it is preferable to use a substantially amorphous polylactic acid resin (A) having a molar ratio of L-lactic acid to D-lactic acid constituting the resin of 92/8 to 8/92. The substantially amorphous polylactic acid resin is a relationship between the heat of fusion (ΔHm) and the heat of crystallization (ΔHc) obtained by differential scanning calorimetry (based on JIS-K7122) at a temperature increase of 10 ° C./min ( It means a polylactic acid resin (A) having a ΔHm−ΔHc) of 3 J / g or less. When the molar ratio of L-lactic acid or D-lactic acid exceeds 92%, the polylactic acid resin (A) is easily crystallized depending on the film forming conditions. Since this crystal does not melt at the sealing temperature, it functions to reduce the sealing strength. More realistic and preferred molar ratios of L-lactic acid and D-lactic acid are 90/10 to 75/25 and 10/90 to 25/75.

  As the aliphatic polyester resin (B) having a glass transition temperature Tg of 10 ° C. or lower and a melting point of 70 ° C. or higher and 120 ° C. or lower used in the present invention, an aliphatic polyester resin produced by a microorganism, for example, Aliphatic polyesters such as poly (hydroxyalkanoic acid) biosynthesized in the microbial cells, aliphatic polyester resins by chemical synthesis, for example, aliphatic polyesters obtained by polycondensation of aliphatic dicarboxylic acid and aliphatic diol as main components, cyclic Examples thereof include aliphatic polyesters obtained by ring-opening polymerization of lactones, synthetic aliphatic polyesters, resins whose types are partially modified, and mixtures thereof. Examples of the aliphatic polyester obtained by polycondensation of an aliphatic dicarboxylic acid and an aliphatic diol as main components include succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid and the like, Examples include polycondensation selected from one or more aliphatic diols such as ethylene glycol, 1,3-propion glycol, 1,4-butanediol, and 1,4-cyclohexanedimethanol. Examples of aliphatic polyesters obtained by ring-opening polymerization of cyclic lactones include ring-opening polymers selected from one or more cyclic monomers such as ε-caprolactone, δ-valerolactone, and β-methyl-δ-valerolactone. Can be mentioned. Examples of synthetic aliphatic polyesters include copolymers of succinic anhydride, cyclic acid anhydrides such as ethylene oxide and propylene oxide, and oxans. Among the above, taking into account the crystallization speed and crystallinity, preferred examples include polybutylene succinate, poly (butylene succinate / adipate), polyethylene succinate, poly (ethylene succinate / adipate), polyhydroxyalkanoate Etc.

  If the melting point of the aliphatic polyester resin (B) is less than 70 ° C., problems such as handling during film formation and blocking during storage of the raw film are likely to occur. Since it is difficult, it is not preferable from the viewpoint of high-speed bag-making. More preferably, they are 70 degreeC or more and 90 degrees C or less, More preferably, they are 70 degreeC or more and 85 degrees C or less, Most preferably, they are 75 degreeC or more and 85 degrees C or less.

  As the lubricant (D) used in the present invention, an inorganic lubricant or an organic lubricant is used. Examples of inorganic lubricants include talc, silica, zeolite, and mica. Examples of organic lubricants include fatty acid amides, fatty acid salts, silicon compounds, and waxes. The fatty acid amides include caproic acid amide, caprylic acid amide, capric acid amide, lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, arachidic acid amide, behenic acid amide, palmitoleic acid amide, oleic acid amide, eicosene Acid amide, erucic acid amide, elaidic acid amide, trans-11-eicosenoic acid amide, trans-13-docosenic acid amide, linoleic acid amide, linolenic acid amide, ricinoleic acid amide, ethylenebisstearic acid amide, erucic acid amide, etc. is there. Examples of fatty acid salts include zinc stearate, calcium stearate, magnesium stearate, aluminum stearate, barium stearate, lithium stearate, lead stearate, sodium oleate, barium laurate, zinc laurate and the like. Also, methyl laurate, methyl myristate, methyl palmitate, methyl stearate, methyl oleate, methyl erucate, methyl behenate, butyl laurate, butyl stearate, isopropyl myristate, isopropyl palmitate, palmitic acid Examples also include monoester organic lubricants such as octyl, coconut fatty acid octyl ester, octyl stearate, lauryl laurate, stearyl long stearate, higher alcohol ester of long chain fatty acid, behenine behenate and cetyl myristate. Among these, organic lubricants are preferably used, and among these, fatty acid amides are preferable, and erucic acid amide, ethylenebisstearic acid amide, stearic acid amide, and the like are used.

  The addition amount of the lubricant (D) is 0.01 to 0.00 with respect to 100 parts by mass of the total amount of the polylactic acid resin (A) and the aliphatic polyester resin (B) having a glass transition temperature Tg of 10 ° C. or less. 5 parts by mass. If it is less than 0.01 part by mass, it is difficult to obtain the effect of reducing the dynamic friction coefficient (μd) on the surface of the packaging film, and if it exceeds 0.5 part by mass, the dynamic friction coefficient (μd) on the surface of the packaging film is excessively lowered. This will affect handling problems and reduce seal strength. A more preferable range is 0.05 to 0.3 part by mass.

  The dynamic friction coefficient (μd) is a physical property related to the slipperiness of the packaging film, and when the dynamic friction coefficient (μd) is in the range of 0.15 or more and 0.5 or less, excellent packaging machine aptitude is expressed. When it is less than 0.15, the original fabric is unwound by itself, or when the film is formed and wound, defects in the winding shape tend to occur, making it difficult to handle the original fabric. When the ratio exceeds 0.5, troubles such as film breakage due to slip failure are likely to occur in the packaging machine. In consideration of high-speed bag-making properties, a more preferable dynamic friction coefficient (μd) is 0.17 or more and 0.45 or less, and more preferably 0.2 or more and 0.4 or less.

  In the present invention, when the melting point of the aliphatic polyester resin (B) is 70 ° C. or higher and 85 ° C. or lower, the crystal nucleating agent (C) is preferably used. The aliphatic polyester resin (B) having a melting point in the range described above has a low crystallization rate and a low crystallinity, and therefore has a non-slip property when used on the film surface. Therefore, by using the crystal nucleating agent (C), the crystallization degree and the crystallization speed of the aliphatic polyester resin (B) can be improved. As a result, the bleed-out speed of the lubricant (D) is improved, and it is considered that more stable slidability can be expressed over time. As such a crystal nucleating agent (C), fatty acid salts and aliphatic polyester resins can be used in addition to inorganic fillers and layered silicates having a particle size of 10 μm or less. As the inorganic filler, talc or silica can be used, and as the layered silicates, there are montmorillonite, mica and the like. Moreover, the filler which performed the surface treatment by the silane coupling etc. can also be used for the purpose of a dispersibility improvement. Examples of fatty acid salts include zinc stearate, calcium stearate, magnesium stearate, aluminum stearate, barium stearate, lithium stearate, lead stearate, sodium oleate, barium laurate, zinc laurate and the like. From the viewpoint of sealing properties, the crystal nucleating agent (C) is preferably an aliphatic polyester resin.

  As an aliphatic polyester-type resin (C2) used as a crystal nucleating agent (C), the thing of the structure similar to the aliphatic polyester-type resin (B) mentioned above can be used. In particular, the melting point (Tmc) of the aliphatic polyester resin (C2) is preferably higher than 85 ° C. and lower than 170 ° C. When Tmc is higher than 85 ° C., the effect can be exhibited as the crystal nucleating agent (C) of the low temperature sealant layer. A Tmc of 170 ° C. or higher is not preferable because it affects the melting characteristics during extrusion. More preferable (Tmc) is 90 ° C. or higher and 120 ° C. or lower.

  The relationship between the crystallization temperature (Tcc) of the aliphatic polyester resin (C2) used as the crystal nucleating agent (C) and the crystallization temperature (Tcb) of the aliphatic polyester resin (B) is 10 ° C. ≦ (Tcc−Tcb) Those satisfying ≦ 100 ° C. are preferably used. If 10 ° C.> (Tcc−Tcb), the aliphatic polyester resin (C2) may not exhibit a sufficient effect as a crystal nucleating agent, and if (Tcc−Tcb)> 100 ° C., the crystallization temperature. May cause problems with low-temperature sealability. More preferably, 15 ° C. ≦ (Tcc−Tcb) ≦ 50 ° C.

  The aliphatic polyester resin (C2) having a weight average molecular weight (Mw) of 80,000 to 170,000 is preferably used. By setting it as such molecular weight, there exists an effect which makes the crystallization speed | rate of an aliphatic polyester-type resin (B) faster. Furthermore, since the fluidity of the resin at the time of sealing is improved, there is also an effect that enables a seal with better airtightness. When the weight average molecular weight exceeds 170,000, the effect of improving the airtightness at the time of sealing is small, and when the weight average molecular weight is less than 80,000, hydrolysis of the aliphatic polyester resin (B) is promoted and the sealing strength is lowered. Sometimes A more preferred weight average molecular weight is 100,000 or more and 150,000 or less.

  The mixture of the aliphatic polyester resin (B) and the crystal nucleating agent (C) used in the sealant layer of the present invention was determined at 10 ° C./min during temperature reduction by differential scanning calorimetry (based on JIS-K-7122). The crystallization heat quantity ΔHc is preferably 10 J / g or more and 50 J / g or less. By having such a degree of crystallinity, more stable slipperiness can be expressed. If it is less than 10 J / g, the stability of slipperiness may be a problem, and if it exceeds 50 J / g, flexibility may be a problem. More preferable ΔHc is 18 J / g or more and 40 J / g, and further preferably 20 J / g or more and 35 J / g or less.

  The content of the crystal nucleating agent (C) is preferably 0.5% by mass to 40% by mass in the sealant layer as long as the function of the sealant layer is not impaired. If it is less than 0.5% by mass, the effect as a crystal nucleating agent such as improvement in crystallization degree and crystallization speed is difficult to be expressed, and if it is more than 40% by mass, there are problems such as hindering sealability at low temperatures. It may occur. A more preferable addition amount is 1% by mass to 30% by mass, further preferably 2% by mass to 20% by mass, and most preferably 3% by mass to 15% by mass.

  The packaging film of the present invention preferably has a heat seal strength of 15 N / 15 mm or more and 40 N / 15 mm or less. When some force is applied to the packaged film when it is less than 15 N / 15 mm, the sealing surface is liable to peel off, and when it exceeds 40 N / 15 mm, it becomes easy to form a packaging film that is difficult to open. More preferable seal strength is 17 N / 15 mm or more and 35 N / 15 mm or less, and further preferably 20 N / 15 mm or more and 30 N / 15 mm or less. Moreover, it is preferable that the sealing can be performed within a sealing time of 1 second because packaging at a higher speed is possible. More preferably, it is possible to seal within a short time of 0.5 seconds or less, and even more preferably within 0.2 seconds.

  The multi-layer film with a biodegradable sealant layer of the present invention has a base material layer in addition to the sealant layer, and the layer configuration is an asymmetrical configuration such as two or two layers or three or three layers, or two or three layers or three types. It can be a symmetrical configuration such as five layers. As described above, the base material layer is composed of a layer having mechanical properties and functionality required as a packaging film, for example, a heat-resistant layer, a barrier layer, a light-shielding layer, a chemical-resistant layer, and the like. It consists of an adhesive layer for adhering the layers. Moreover, the layer which expresses two or more functions, for example, an adhesive layer having excellent mechanical properties or an adhesive layer having a light shielding function may be used. Among such combinations, a three-layer three-layer configuration or a three-layer five-layer configuration of a heat-resistant layer, an intermediate layer (a layer having excellent mechanical properties, or a layer that exhibits other functions), and a sealant layer is preferably used. The thickness of each layer is not particularly limited as long as the required function can be expressed. As a specific example, the sealant layer has a thickness of 3 μm to 50 μm, preferably 5 μm to 35 μm, and more preferably 8 μm to 20 μm. The thickness can be made as follows. If it is 3 μm or less, the sealing strength may not be sufficiently exhibited, and if it is 50 μm or more, it is not preferable from an economical viewpoint. The thickness of the heat resistant layer is preferably 3 μm or more and 40 μm or less, more preferably 5 μm or more and 20 μm or less. Since the intermediate layer differs depending on the required function, it cannot be determined unconditionally. However, the intermediate layer can have a thickness of 5% to 80% of the total film thickness.

  In the multilayer film with a biodegradable sealant layer of the present invention, a heat-resistant layer may be provided on one of the base material layers. In particular, the melting point (Tm) determined by differential scanning calorimetry (based on JIS-K-7121 and 7122) at a temperature rise of 10 ° C./min is 140 ° C. to 170 ° C., and the heat of fusion (ΔHm) and the heat of crystallization A polylactic acid resin having a (ΔHc) relationship (ΔHm−ΔHc) of 15 J / g to 60 J / g is preferably used as the main component of the heat-resistant layer. The melting point (Tm) is 140 ° C. or higher, and the relationship between the heat of fusion (ΔHm) and the heat of crystallization (ΔHc) (ΔHm−ΔHc) is 15 J / g or higher. And can provide stability of bag making. When Tm exceeds 170 ° C., it is not preferable from the viewpoint of influence on extrusion, and when (ΔHm−ΔHc) exceeds 60 J / g, it is not preferable from the viewpoint of flexibility of the film. Preferable (ΔHm−ΔHc) is 20 J / g or more, and more preferably 30 J / g or more. Moreover, preferable Tm is 150 degreeC or more, More preferably, it is 160 degreeC or more. As such a polylactic acid resin, a polylactic acid resin having a molar ratio of L-lactic acid to D-lactic acid of 100/0 to 95/5 or 5/95 to 0/100 can be used. In view of this, a polylactic acid resin of 100/0 to 95/5 is preferably used. Also, a copolymer of a polylactic acid resin in the above-described ratio and a compound selected from the group consisting of other hydroxycarboxylic acids and / or lactones can be used.

  A crystal nucleating agent or a crystallization accelerator can be added to the heat resistant layer in order to facilitate the crystallization of the polylactic acid resin. Preferred crystal nucleating agents are inorganic fillers and layered silicates having a particle size of 10 μm or less. As the inorganic filler, talc or silica can be used. As layered silicates, montmorillonite, mica and the like can be used. In addition, for the purpose of improving dispersibility, a filler obtained by subjecting the surface of the inorganic filler to a surface treatment such as silane coupling can also be used. Two or more kinds of crystal nucleating agents can be used in combination. The addition amount of the crystal nucleating agent used at this time is 0.5 to 30 parts by mass, more preferably 1 to 20 parts by mass, and further preferably 2 parts by mass with respect to 100 parts by mass of the resin of the heat-resistant layer. Part to 15 parts by mass. When the addition amount exceeds 30 parts by mass, it is not preferable from the viewpoint of transparency and flexibility of the film. In addition, as the crystallization accelerator, a plasticizer and the above-described aliphatic polyester resin and / or aromatic-aliphatic polyester resin having a Tg of 10 ° C. or less may be added simultaneously. For example, polybutylene succinate, poly (butylene succinate / adipate), polyethylene succinate, poly (ethylene succinate / adipate) and the like as aliphatic polyester resin, and poly (butylene terephthalate) as aromatic-aliphatic polyester resin. / Adipate). In addition, a copolymer of polylactic acid and an aliphatic polyester resin and / or an aromatic-aliphatic polyester resin can be used. Examples of the plasticizer include aliphatic polyvalent carboxylic acid esters, fatty acid polyhydric alcohol esters, oxyacid esters, and epoxy plasticizers. Specific examples include triacetin (TA), tributyrin (TB), butylphthalyl butyl glycolate (BPBG), acetyl tributyl citrate (ATBC), dioctyl sebacate, triethylene glycol diacetate, glycerol esters, butyl oleate (BO), adipic acid ether ester, epoxidized soybean oil (ESO), and the like.

  The addition amount of these crystallization accelerators is preferably less than 30% by mass in the heat-resistant layer mass. If it exceeds 30% by mass, the film tends to be deformed at the temperature at the time of heat sealing, and the function of the heat-resistant layer cannot be achieved. Preferably, it is 20 mass% or less.

  The multilayer film with a biodegradable sealant layer of the present invention includes an inorganic filler, an antiblocking agent, a heat stabilizer, an antioxidant, an ultraviolet absorber, an antifogging agent, an antistatic agent, an antirust agent, and an improved impact resistance. It is possible to mix | blend well-known additives, such as an agent, in the range which does not impair the characteristic of this invention.

As the antistatic agent, a surfactant, carbon, conductive polymer, or the like can be used. Various known surfactants, for example, nonionic surfactants such as partial fatty acid esters of polyhydric alcohols, anionic surfactants typified by alkyl sulfonates, and quaternary ammonium salts Cationic surfactants can be used. A surfactant-based antistatic agent is Riken Master GSR350 (trade name) manufactured by Riken Vitamin Co., Ltd., and a static master BO (trade name) manufactured by Riken Technos Co., Ltd. as an antistatic agent for conductive polymers. and so on. By adding these antistatic agents, the surface resistance value can be controlled in the range of 10 ⁹ to 10 ¹² .

  Various known pigments can be added for the purpose of blocking ultraviolet rays and visible light. As a product containing pigment and carbon, there is Early Master (product name) manufactured by Dainichi Seika Co., Ltd. In particular, 1 to 5% by mass of carbons can be added in order to develop light shielding properties.

Next, the manufacturing method of the multilayer film with a biodegradable sealant layer of this invention is demonstrated. As a film forming method of the biodegradable multilayer film of the present invention, a method of casting from a T die to a cooling roll, a conventional film forming method such as an inflation method or a tenter method, unstretched, uniaxially stretched, or simultaneously Alternatively, there is a sequential biaxial stretching method. More specifically, it can be obtained by the following method.
(1) A method in which a tube-shaped or sheet-shaped resin extruded in a molten state is melt-stretched (stretched at a temperature equal to or higher than the melting point) by an inflation method or a cast method in a molten state to form a film.
(2) After the tube-shaped or sheet-shaped resin extruded in the molten state is rapidly cooled and solidified in a state close to the amorphous state, the tube-shaped or sheet-shaped resin is subsequently brought to the glass transition temperature or higher and below the melting point. A method of forming a film by a cold drawing method in which the film is reheated and stretched by an inflation method or a roll tenter method, and, if necessary, after the melt drawing or cold drawing, the film is formed to suppress heat shrinkage of the film. A method in which a film is obtained by heat treatment in a gripped state.

As the stretching ratio of the film or sheet, regardless of the stretching method, the final stretched film or sheet has a thickness of 1/200 times to 1/40 times the extrusion die (die lip) interval. That is, it is preferable to stretch at least uniaxially so that the area of the final stretched film or sheet is 40 to 200 times the area of the film or sheet immediately after the exit of the extrusion die (die lip). (Hereinafter, the ratio of (area of the film or sheet immediately after the outlet of the extrusion die (die lip)) / (area of the final stretched film or sheet) is referred to as “area magnification”.)
Moreover, as a method of forming a multilayer film, a method of manufacturing a film by lamination (extrusion lamination or dry lamination) may be used in addition to the method of forming a multilayer film by coextrusion as described above.

  Among these methods, a method of performing stretching at an area magnification of 40 to 200 times from the die exit by melt stretching is particularly preferable. Under the present circumstances, since the surface is roughened by cooling the surface of a packaging film, it is easy to express slipperiness. More preferably, the area magnification from the die outlet at the time of melt drawing is 60 to 150 times, and more preferably 80 to 140 times.

  Furthermore, the multilayer film with a biodegradable sealant layer formed by the melt stretching method is annealed at a temperature in the vicinity of the Tg of the heat-resistant layer, more specifically in a temperature range of Tg ± 30 ° C. The crystallinity of the heat-resistant layer is further improved, and the heat resistance, that is, the adhesion preventing property to the seal bar can be exhibited. An annealing treatment at a temperature exceeding 30 ° C. above Tg causes film deformation and blocking, and an annealing treatment at a temperature below 30 ° C. below Tg cannot exhibit a sufficient effect. A more preferable annealing temperature is (Tg−20) ° C. or more and (Tg + 15) ° C. or less, and more preferably (Tg−15) ° C. or more and Tg or less.

  When the biodegradable packaging film obtained as described above is used for package packaging of pillow packaging or overlap packaging, continuous high-speed packaging can be performed more stably. In particular, it can also be used for packaging of pocket tissues, ink cartridges, toner cartridges, and the like. Furthermore, with the multilayer film of the present invention, a bag that can be stored and retained for a long period of time without the liquid or gas of the contents leaking from the seal portion can be obtained.

  In addition, when used as a pillow type air cushioning material or an air cushioning material with a reverse valve, there is little air leakage, excellent compression creep resistance and pressure strength, and practically sufficient cushioning performance can be maintained for a long time. An air cushioning material is obtained.

  The present invention will be described based on examples.

The evaluation methods used in the examples and comparative examples are described below.
(1) Measurement of coefficient of dynamic friction (μd) Measurement was performed based on ASTM D-1894, and the rider used for the measurement was made of 500 g satin metal. In addition, after film formation, what was stored at room temperature for 24 hours was measured, and the dynamic friction coefficient (μd) immediately after film formation was measured, and what was stored at room temperature for one year was measured to determine the dynamic friction coefficient (μd) after one year. did.
(2) D-, L-lactic acid composition and optical purity of polylactic acid polymer The composition ratio of L-lactic acid and / or D-lactic acid monomer units constituting the polylactic acid polymer is determined by alkalinizing the sample with 1N-NaOH. High-performance liquid chromatography (trade name, HPLC: LC-10A-) manufactured by Shimadzu Corporation equipped with an optical isomer separation column was used for the hydrolyzed sample (liquid) neutralized with 1N HCl after concentration and adjusted with distilled water. VP), the weight ratio of L-lactic acid constituting the polylactic acid polymer [L] (unit%) from the detection peak area ratio of L-lactic acid and D-lactic acid at UV UV of 254 nm (area measurement by perpendicular method) The weight ratio [D] (unit%) of D-lactic acid constituting the polylactic acid polymer was determined, and the measured value was obtained by calculating the arithmetic average (rounded off) of three points per polymer.
(3) Heat of fusion (ΔHm), heat of crystallization (ΔHc), crystallization temperature (Tc), melting point (Tm)
In accordance with JIS-K-7121 and 7122, using a differential scanning calorimeter (DSC) manufactured by Perkin-Elmer Co., at a nitrogen gas flow rate of 25 ml / min, a temperature of 10 ° C./0° C. to 200 ° C. The temperature was raised in minutes, and the heat of crystallization ΔHc, heat of fusion ΔHm, and melting point Tm at the time of temperature rise were measured.
(4) Seal strength (N / 15mm)
The seal strength of the film is measured according to JIS-Z1707, the seal pressure is 0.65 MPa, the seal time is 0.2 seconds, and the seal strength is measured every 10 ° C. in the temperature range from 80 ° C. until the film melts. The value was taken as the seal strength of the film. A seal bar having a width of 5 mm was used.
(5) Suitability for packaging machine Using an air cushion bag making machine 150 made by Tricon Corporation, bag making was carried out at 150 pieces / minute, and the following indexes were used for evaluation.
○: When the bag is made of the original fabric 1000m, the film is cut 0 times. Δ: When the original fabric is 1000m, the film is cut once or twice. ×: When the bag is made 1000m, the film is cut. (6) Air cushioning material compression creep In accordance with JIS-K-6767, one air cushioning material was subjected to a compression creep test using a weight of 2 kg. Under the present circumstances, the thickness of the air cushioning material after 1 day was made into the initial thickness, and it evaluated with the following parameters | indexes.
A: The thickness after 7 days is 80% or more of the initial thickness. B: The thickness after 7 days is 20% or more of the initial thickness. Δ: After 7 days, the air was completely removed.
X: After one day, the air was completely removed.

The biodegradable polymers used in the following examples and comparative examples are shown below. However, the composition of the resin in the present invention is not limited to this.
A1: Polylactic acid (4032D (trade name) manufactured by Cargill Dow Co., Ltd., D lactic acid content = 1.4%, molecular weight = 240,000, Tg = 58 ° C., Tm = 166 ° C.)
A2: Polylactic acid (4042D (trade name) manufactured by Cargill Dow, D lactic acid content = 4.2%, molecular weight = 230,000, Tg = 58 ° C., Tm = 158 ° C.)
A3: Polylactic acid (4060D (trade name) manufactured by Cargill Dow, D lactic acid content = 12.6%, molecular weight = 250,000, Tg = 58 ° C.)
B1: Polybutylene succinate adipate (Bionore 5001D (trade name) manufactured by Showa Polymer Co., Ltd., molecular weight = 240,000, Tg = −53 ° C., Tm = 79 ° C., Tc = 47 ° C.)
B2: Polybutylene succinate adipate (Bionor # 3001 (trade name), Showa Polymer Co., Ltd., molecular weight = 230,000, Tg = −43 ° C., Tm = 93 ° C., Tc = 66 ° C.)
B3: Polybutylene succinate adipate (Bionor # 3020 (trade name), Showa Polymer Co., Ltd., molecular weight = 140,000, Tg = -45 ° C, Tm = 92 ° C, Tc = 66 ° C)
B4: Polybutylene succinate (Bionole # 1001 (trade name) manufactured by Showa Polymer Co., Ltd., molecular weight = 250,000, Tg = −32 ° C., Tm = 113 ° C., Tc = 88 ° C.)
B5: Polybutylene succinate (Bionore # 1050 (trade name), Showa Polymer Co., Ltd., molecular weight = 110,000, Tg = −33 ° C., Tm = 112 ° C. Tc = 86 ° C.)
Talc: LMS200 (trade name) manufactured by Fuji Talc Industrial Co., Ltd.
Sliding agent: erucic acid amide [Example 1]
Using a twin screw extruder, erucic acid amide and raw material B1 were mixed so as to have the ratio shown in Table 1 to prepare a master batch. Similarly, a master batch with a raw material A1 and a talc concentration of 39% by mass was prepared, and after blending the raw materials so that the final composition became the composition shown in Table 1, it was shown in Table 1 using a single screw extruder. The extruder of each layer was controlled so that the layer structure and the thickness of each layer were obtained, and the molten resin was extruded using a three-layer die. During extrusion, the outer die lip diameter is 110 mm, the inner die lip diameter is 105 mm, and the lip clearance is 2.5 mm. The air is blown into the tube while blowing air at about 25 ° C from the cooling ring to the molten resin extruded in a tube shape. Injected to form bubbles. The obtained film was guided to a pinch roll, and the tube-shaped film was wound up with a winding roll as two flat films. Next, after the bubbles were stabilized, the resin extrusion speed, the amount of air injected into the bubbles, and the film winding speed in the pinch roll were finely adjusted to obtain a film having the final thickness shown in Table 1. The film was slit so as to have a width of 190 mm, and an air cushioning material having a length of 140 mm was prepared using an air cushioning bag making machine 150 manufactured by Tricon Sales Co., Ltd.
[Examples 2 to 4, Comparative Examples 1 to 3]
In the same manner as in Example 1, a film was produced with the composition and layer configuration shown in Table 1, and an air cushioning material was produced.

The multilayer film with a biodegradable sealant layer of the present invention can be smoothly fed in a packaging (bag making) machine, has excellent suitability for a high-speed packaging machine, and has sufficient sealing strength, so that the contents can be retained. Can be suitably used for biodegradable packaging films, bag-like articles, and air cushioning materials.

Claims (10)

A biodegradable multilayer film having a sealant layer on at least one surface, wherein the sealant layer has a polylactic acid resin (A) and a glass transition temperature Tg of 10 ° C. or lower and a melting point of 70 ° C. or higher and 120 ° C. or lower. consist of a mixture of the lubricant (D) is a family polyester resin (B) and fatty acid amides, (a) and the mixing weight ratio of (B) is (a) / (B) = 55 / 45~13 / 87 (D) is 0.01 to 0.5 parts by mass with respect to 100 parts by mass of the total amount of (A) and (B), and the dynamic friction coefficient (μd) of the surface having the sealant layer is 0. A multilayer film with a biodegradable sealant layer that is 15 or more and 0.5 or less. 2. The polylactic acid resin (A) is a substantially amorphous polylactic acid resin having a molar ratio of L-lactic acid and D-lactic acid constituting the resin of 92/8 to 8/92. A multilayer film with a biodegradable sealant layer as described in 1. The multilayer film with a biodegradable sealant layer according to claim 1 or 2, wherein the aliphatic polyester resin (B) has a melting point of 70 ° C or higher and 85 ° C or lower. Furthermore, the crystal nucleating agent (C) is contained, and the addition amount of the crystal nucleating agent (C) is 0 with respect to 100 parts by mass of the total amount of the polylactic acid resin (A) and the aliphatic polyester resin (B). The multilayer film with a biodegradable sealant layer according to claim 3, wherein the multilayer film is 5 parts by mass or more and 43 parts by mass or less. The biodegradable sealant according to claim 4, wherein the crystal nucleating agent (C) is an aliphatic polyester (C2), and the melting point of the aliphatic polyester resin (C2) is higher than 85 ° C and lower than 170 ° C. Multilayer film with layers. The multilayer film with a biodegradable sealant layer according to claim 5, wherein the molecular weight of the aliphatic polyester resin (C2) is 170,000 or less. It is composed of a polylactic acid resin having a molar ratio of L-lactic acid and D-lactic acid constituting the resin of 95/5 to 100/0 and a crystal nucleating agent, and is determined by differential scanning calorimetry at a temperature rise of 10 ° C./min. And at least one heat-resistant layer having a melting point (Tm) of 140 ° C. to 170 ° C. and a relationship of heat of fusion (ΔHm) and crystallization heat (ΔHc) (ΔHm−ΔHc) of 15 J / g to 60 J / g. Item 7. A multilayer film with a biodegradable sealant layer according to any one of Items 1 to 6 . The biodegradation according to any one of claims 1 to 7, wherein the resin constituting each layer is coextruded, and the film is melt-stretched to form a film in a molten state under a condition where the draw ratio is 40 to 200 times in terms of area magnification. For producing a multilayer film with a conductive sealant layer. A bag-shaped article using the biodegradable packaging film according to claim 1. The airbag cushioning material using the biodegradable packaging film in any one of Claims 1-7.