JP2012177045A - Polylactic acid-based film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biodegrable film which can be preferably used as a mulch film for agriculture or a sheet for fumigating a pine weevil, and to provide especially a polylactic acid-based film which can achieve both biodegrability and productivity.SOLUTION: The film is formed of a composition containing polylactic acid-based resin. The composition contains 30 mass% or more of polylactic acid-based resin in 100 mass% of total components of the composition. The polylactic acid-based resin has a maximum value of at least one molecular weight peak in a region having a molecular weight of 100,000 or more, and a maximum value of at least one molecular weight peak in a region having a molecular weight of less than 100,000 in its molecular weight distribution.

Description

  The present invention relates to a biodegradable film that can be preferably used for agricultural multi-film applications or pine worm fumigation sheet applications, and particularly relates to a polylactic acid-based film having both biodegradability and manufacturability.

  Currently, in the agricultural field, agricultural multi-films are widely used for the purpose of improving crop growth and yield. As a general usage method of the agricultural multi-film, a ridge having a mountain-shaped or trapezoidal cross-section and a long and straight soil is raised, covered with the ridge, and used to cover the soil surface. The crops are pierced with multi-films for planting, and seedlings are planted there. Multi-films are used for purposes such as water retention and heat retention until the seedlings are fully rooted in the soil, weed growth control until the seedlings are grown and the crops are harvested, and the shape of the straw is maintained. Has been.

  On the other hand, in the field of forestry, the damage caused by pine forests such as pine weevil, pine beetle, pine beetle and other pine beetles has been increasing, causing great damage to pine growth. Yes. In the transportation field, there are many cases where harmful pests are lurking in the wood pallets used for import and export of various large-sized products. Have moved to other countries, leading to the destruction of the country's natural environment. In order to prevent such damage of pine worms, the dead tree of pine trees damaged by pine worms is covered and enclosed with a plastic pine worm insect fumigation sheet, and methyl isopropyl, an active ingredient for fumigation, is enclosed. Treatment with a fumigant with thiocyanate (MITC) is performed. Even in the case of disinfection of wood, in many cases, the wood just after cutting is piled up outdoors, covered with plastic pine worm insect fumigation sheets, hermetically enclosed, and MITC is fumigated. Yes.

  Many of these agricultural multi-films and pine worm fumigation sheets are made of polyolefins such as polyethylene, but polyolefins do not biodegrade even if left in the natural environment, so they must be recovered after use. There is. Also, physically deteriorated and dirty multi-films and fumigation sheets after use are difficult to reuse, and in most cases, there is no other way but to dispose of them or incinerate them. There was a problem of adversely affecting.

  To solve these problems, the period of use as agricultural multi-films and pine worm fumigation sheets can be used in the same way as conventional polyolefin, and after use, soil microorganisms, moisture, UV A biodegradable agricultural multi-film and a sheet for pine worm fumigation that are completely decomposed by, for example, are being studied. For these biodegradable agricultural multifilms and pine worm fumigation sheets, films using biodegradable resins such as aliphatic polyesters and aliphatic aromatic polyesters with specific structures have been studied. Yes.

  Patent Document 1 discloses a biodegradable film useful as an agricultural multifilm, characterized by blending an aliphatic aromatic polyester resin and an aliphatic polyester resin in a specific blending amount.

  Patent Document 2 discloses a pine worm fumigation sheet characterized by blending aliphatic aromatic polyester, polyethylene succinate, and aliphatic polyester having a long chain branch in a specific blending amount.

  Thus, biodegradable agricultural multi-films and pine worm fumigation sheets have been developed around soft biodegradable resins produced from petroleum-derived raw materials, but in recent years, In the field of plastic products, plant-derived raw material plastics originally derived from carbon sources (carbon dioxide) in the atmosphere have attracted attention in the field of plastic products. ing. Among them, polylactic acid, which is excellent in transparency and relatively advantageous in terms of cost, is being studied for practical use as a biodegradable agricultural multi-film and a sheet for pine worm fumigation. When it is going to be applied to soft film applications typified by polyolefins, it is not sufficient in flexibility and impact resistance, so various attempts have been made to improve these properties and put them into practical use.

For example, Patent Document 3 discloses a film made of a composition obtained by adding polylactic acid to a polyhydric alcohol ester or hydroxy polycarboxylic acid ester plasticizer, SiO ₂ as an anti-blocking agent, and a lubricant. Patent Document 4 discloses a film made of polylactic acid, an aliphatic polyester having a glass transition point of 0 ° C. or less, and a plasticizer. Patent Document 5 discloses a film made of a lactic acid resin and a plasticizer, which is mainly intended for use in stretch packaging. Patent Document 6 discloses a film obtained by further crystallizing a film composed of a plurality of types of polylactic acid having different D-form concentrations and a plasticizer. Patent Document 7 discloses a film made of polylactic acid, an aliphatic polyester, and a specific plasticizer. Patent Document 8 discloses a multifilm composed of polylactic acid, a biodegradable aliphatic aromatic copolymer polyester having a glass transition temperature of 0 ° C. or lower, an oxyester plasticizer, and an inorganic filler.

  Patent Document 9 discloses a polylactic acid-based film excellent in flexibility, impact resistance, and bleed resistance using polylactic acid and a plasticizer that is solid at room temperature.

JP 2003-001704 A JP 2006-246786 A JP-A-8-34913 JP 2000-273207 A JP 2003-12934 A JP 2006-45290 A Japanese Patent No. 3753254 JP 2004-57016 A JP 2009-138085 A

  Since all of the techniques of Patent Documents 3 to 8 use a plasticizer that is a liquid at room temperature, there was a certain effect in terms of imparting flexibility, impact resistance, etc. to polylactic acid. Inherently easy to bleed, lack of stability over time in performance, and easy to block. In addition, the biodegradability of the biodegradable film tends to be improved by adding a liquid plasticizer. However, the amount of the liquid plasticizer added is limited to maintain the manufacturability of the film. Since the agent bleeds out over time, the biodegradability may not be sufficient when it is used as a biodegradable agricultural multi-film or a pine worm fumigation sheet. There was no effective suggestion about the technology to compensate for the drawbacks on the left.

  Although the technique described in Patent Document 9 is somewhat suppressed from bleeding out of the plasticizer compared to the techniques described in Patent Documents 3 to 8, the amount of plasticizer added is still limited and biodegradable. In some cases, the biodegradability is not sufficient when the agricultural multi-film or the pine worm fumigation sheet having the above is used. There was no effective suggestion about the technology to compensate for the drawbacks on the left.

  When biodegradability is not sufficient, agricultural multi-films can be entangled in the rotary of a tiller or agricultural tractor when sown into the soil, or film fragments in the process of scattering can be scattered over a wide area for a long time. However, there are problems such as hindering the growth of crops. Moreover, as a sheet | seat for pine worm insect fumigation, there exists a problem that the sheet piece in the middle of decomposition | disassembly is scattered over a wide range over a long period of time, and a landscape worsens.

  Further, in Patent Documents 3 to 9, when the amount of liquid plasticizer or plasticizer added is increased so as to obtain sufficient decomposability, for example, during production by the inflation method, bubbles become unstable, and the film width Stable manufacturing becomes difficult due to fluctuations in thickness and thickness.

  As described above, in order to achieve both manufacturability and biodegradability, various studies have been made on polylactic acid-based biodegradable multifilms, but they have not yet been achieved.

  Therefore, in view of the background of such prior art, the present invention relates to a biodegradable film that can be preferably used for agricultural multi-film applications or pine worm fumigation sheet applications, and in particular, achieves both biodegradability and manufacturability. An improved polylactic acid film is to be provided.

In order to solve the above problems, the present invention employs the following means. That is, the polylactic acid film of the present invention is
A film comprising a composition containing a polylactic acid-based resin,
The composition contains 30% by mass or more of a polylactic acid resin in 100% by mass of all the components of the composition,
In the molecular weight distribution, the polylactic acid-based resin has at least one maximum value of molecular weight peak in a region having a molecular weight of 100,000 or more, and has at least one maximum value of molecular weight peak in a region having a molecular weight of less than 100,000. It is a polylactic acid film characterized by being a thing.

  Moreover, the preferable aspect of the said polylactic acid-type film is (1) 30 mass% or more and 95 mass% or less of polylactic acid-type resin of molecular weight 100,000 or more in the molecular weight distribution in the said polylactic acid-type resin 100 mass%, and 5 wt% or more and 30 wt% or less of a polylactic acid resin having a molecular weight of less than 100,000 in the molecular weight distribution; (2) In 100 wt% of all the components of the composition, subcomponents are 5 wt% or more and 45 wt% or less. And the subcomponent is at least one resin selected from the group consisting of aliphatic aromatic polyesters, aliphatic polyesters, and polyolefins, and (3) the subcomponent is polybutylene succinate, polybutylene succin. At least one resin selected from the group consisting of nate adipate and polybutylene terephthalate adipate (4) In the total composition of 100% by mass of the composition, the plasticizer is contained in an amount of 5% by mass to 30% by mass, and (5) in a molecular weight distribution of less than 100,000 in the molecular weight distribution of the polylactic acid resin. The maximum value of at least one peak is derived from a recycled polylactic acid resin.

  The present invention relates to a biodegradable film that can be preferably used for agricultural multi-film use or pine worm fumigation sheet use, and in particular, provides a polylactic acid-based film having both biodegradability and manufacturability. Is done.

  The present invention relates to a biodegradable film that can be preferably used for the above-mentioned problems, that is, for agricultural multifilm use or for pine worm fumigation sheet use. As a result, by making a polylactic acid-based film comprising a composition containing 30% by mass or more of a polylactic acid-based resin having a specific molecular weight distribution, both productivity and biodegradability can be achieved. It has been found for the first time that it has been found that it can be preferably used for sheeting for insectivorous fumigation, and has solved this problem for the first time.

  Hereinafter, the polylactic acid film of the present invention will be described.

  The polylactic acid resin contained in the composition constituting the polylactic acid film of the present invention is mainly composed of L-lactic acid and / or D-lactic acid, and the lactic acid-derived component is 70% by mass or more and 100% by mass or less. Homopolylactic acid consisting essentially of L-lactic acid and / or D-lactic acid is preferably used.

  The polylactic acid-based resin contained in the composition constituting the polylactic acid-based film of the present invention has at least one maximum molecular weight peak in a region having a molecular weight of 100,000 or more in the molecular weight distribution, and has a molecular weight of 100,000. It is necessary to have a maximum value of at least one molecular weight peak in the region below. The molecular weight distribution here can be obtained by comparison with standard polystyrene using gel permeation chromatography (GPC) and chloroform as a developing solvent. The molecular weight in the present invention is the molecular weight. Refers to any numerical value (in the X axis) in the distribution.

  In addition, the upper limit is not limited for a region having a molecular weight of 100,000 or more, but it is difficult to practically indicate the maximum value of the molecular weight peak in a region having a molecular weight exceeding 500,000. The molecular weight is 500,000. The maximum value of the molecular weight peak in the region having a molecular weight of 100,000 or more is preferably such that the maximum value of at least one peak is in the range of 120,000 to 160,000.

  On the other hand, in the region having a molecular weight of less than 100,000, the peak maximum value derived from low molecular weight components such as monomers and oligomers, that is, the peak maximum value may be shown in the region having a molecular weight of 3,000 or less. When considering the molecular weight distribution and molecular weight of the polylactic acid resin in, the region having a molecular weight of 3,000 or less is excluded. That is, the polylactic acid resin in the present invention means a resin having a molecular weight of more than 3,000. Regarding the maximum value of the molecular weight peak in the region having a molecular weight of less than 100,000, the maximum value of at least one peak is preferably in the range of 50,000 to 9,9000.

  Such a polylactic acid resin having a molecular weight distribution can be obtained by blending two or more polylactic acid resins having different number average molecular weights. For example, 70% by mass of a polylactic acid resin having a number average molecular weight of 200,000 and 30% by mass of a polylactic acid resin having a number average molecular weight of 80,000 are mixed and melt-kneaded using a twin screw extruder to obtain a molecular weight of 150,000. Thus, a polylactic acid resin having a peak maximum value at a molecular weight of 50,000 can be obtained.

  The polylactic acid resin constituting the polylactic acid film of the present invention has, in its molecular weight distribution, a maximum value of at least one molecular weight peak in a region having a molecular weight of 100,000 or more and at least in a region having a molecular weight of less than 100,000. Although it is necessary to have a maximum value of one molecular weight peak, a plurality of maximum values of molecular weight peaks in each region may be included. Preferably, from the viewpoints of biodegradability and manufacturability, the maximum number of molecular weight peaks in each region is 3 or less. When the maximum value of four or more peaks is present in a region having a molecular weight of 100,000 or more, biodegradability may be deteriorated, and the maximum value of four or more peaks is determined in a region having a molecular weight of less than 100,000. When it has, manufacturability may deteriorate.

  Further, the maximum value of at least one peak in the region of molecular weight less than 100,000 in the polylactic acid resin constituting the polylactic acid film of the present invention is a maximum value derived from the recycled polylactic acid resin. It is preferable. In other words, as a polylactic acid resin to be blended in order to obtain the maximum value of at least one peak in the molecular weight distribution region of less than 100,000 in the molecular weight distribution, it is possible to use a recycled polylactic acid resin from the viewpoint of production cost. Particularly preferred.

  Here, the recycled polylactic acid-based resin includes a resin-introduced portion called a spool or a runner at the time of injection molding, or an ear that has been cut to a standard length at the time of molding processing of spinning, sheet, film, nonwoven fabric, etc. Examples of the parts at both ends called “recovered”, a recovered product of a used molded product, and the like can be given. In the case of a polylactic acid film comprising a composition containing these recycled polylactic acid resins, flakes obtained by pulverizing these recycled polylactic acid resins may be used, or melt extrusion or You may use the pellet or chip | tip obtained by granulating with a granulator.

  In addition, the polylactic acid resin contained in the composition constituting the polylactic acid film of the present invention is a polylactic acid resin having a molecular weight of 100,000 or more in the molecular weight distribution when the total components of the polylactic acid resin are 100% by mass. It is preferable that the resin contains 30% by mass or more and 95% by mass or less of a polylactic acid resin having a molecular weight of less than 100,000 in the molecular weight distribution, and preferably contains 5% by mass or more and 70% by mass or less of polylactic acid resin having a molecular weight of 100,000 or more. It is particularly preferable that the polylactic acid resin is contained in an amount of 40% by mass or more and 70% by mass or less and a molecular weight distribution of less than 100,000 in the molecular weight distribution.

  The content of the polylactic acid resin having a molecular weight of 100,000 or more and the polylactic acid resin having a molecular weight of less than 100,000 in 100% by mass of the polylactic acid resin can be obtained by calculating from the molecular weight distribution of the polylactic acid resin. it can.

  Moreover, when calculating content of polylactic acid-type resin, it calculates excluding low molecular weight components, such as a monomer and an oligomer, ie, the area | region of molecular weight 3,000 or less. That is, the polylactic acid resin in the present invention means a resin having a molecular weight of more than 3,000. When the polylactic acid resin having a molecular weight of 100,000 or more exceeds 95% by mass and / or the polylactic acid resin having a molecular weight of less than 100,000 is less than 5% by mass in 100% by mass of the polylactic acid resin, sufficient biodegradability is achieved. For example, when it is used as an agricultural multi-film, it may get entangled in the rotary of a cultivator or agricultural tractor when it is sown into the soil, This may cause problems such as scattering over a wide area and hindering the growth of crops.For example, as a sheet for fumigation of pine worms, a sheet piece in the middle of decomposition is scattered over a wide area for a long period of time, resulting in a poor landscape. Problems such as becoming may occur.

  In addition, when the polylactic acid resin having a molecular weight of 100,000 or more is less than 30% by mass and / or the polylactic acid resin having a molecular weight of less than 100,000 is more than 70% by mass in 100% by mass of the polylactic acid resin, sufficient productivity can be obtained. In some cases, for example, at the time of production by an inflation method, stable production may be difficult due to unstable bubbles and fluctuations in film width and thickness.

  The weight average molecular weight of the polylactic acid resin in the composition constituting the polylactic acid film of the present invention is preferably 50,000 or more, more preferably 80,000 to 400,000, and 100,000 to 300,000. It is particularly preferred that By setting the weight average molecular weight of the polylactic acid resin component to 50,000 or more, the polylactic acid-based mechanical properties of the present invention can be made excellent. Here, the weight average molecular weight can be obtained by comparison with standard polystyrene using gel permeation chromatography (GPC) and using chloroform as a developing solvent.

  The polylactic acid resin in the composition constituting the polylactic acid film of the present invention preferably has crystallinity. The polylactic acid resin has crystallinity when the polylactic acid resin is sufficiently crystallized under heating and then subjected to differential scanning calorimetry (DSC) measurement in an appropriate temperature range. This means that the heat of crystal melting derived from is observed. When the polylactic acid resin used in the present invention has crystallinity, it is suitable for imparting blocking resistance when a composition containing the polylactic acid resin is used as a film.

  In general, homopolylactic acid has higher melting point and crystallinity as the optical purity is higher. The melting point and crystallinity of polylactic acid are affected by the molecular weight distribution and the catalyst used during polymerization. Usually, homopolylactic acid having an optical purity of 98% or higher has a melting point of about 170 ° C. and a relatively high crystallinity. Further, as the optical purity is lowered, the melting point and crystallinity are lowered. For example, homopolylactic acid having an optical purity of 88% has a melting point of about 145 ° C., and homopolylactic acid having an optical purity of 75% has a melting point of about 120 ° C. It is. Homopolylactic acid with an optical purity lower than 70% does not show a clear melting point and is amorphous.

  The polylactic acid resin in the composition constituting the polylactic acid film of the present invention can be mixed with crystalline homopolylactic acid and amorphous homopolylactic acid for the purpose of imparting or improving necessary functions. It is. In this case, the proportion of amorphous homopolylactic acid may be determined within a range that does not impair the effects of the present invention. When a relatively high heat resistance is desired when a polylactic acid film is used, it is preferable that at least one of the polylactic acid resins used contains polylactic acid having an optical purity of 95% or more.

  In addition, the polylactic acid resin in the composition constituting the polylactic acid film of the present invention is a copolymerized polymer obtained by copolymerizing other monomer components having ester forming ability in addition to L-lactic acid and D-lactic acid. Lactic acid may be used. Examples of copolymerizable monomer components include glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid, 6-hydroxycaproic acid, and other hydroxycarboxylic acids, as well as ethylene glycol, propylene glycol, and butane. Compounds containing a plurality of hydroxyl groups in the molecule such as diol, neopentyl glycol, polyethylene glycol, glycerin, pentaerythritol or their derivatives, succinic acid, adipic acid, sebacic acid, fumaric acid, terephthalic acid, isophthalic acid, 2 , 6-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, 5-tetrabutylphosphonium sulfoisophthalic acid and the like, or compounds containing a plurality of carboxylic acid groups in the molecule. In addition, it is preferable to select the component which has biodegradability among the above-mentioned copolymerization components according to a use.

  Although the details of the method for producing the polylactic acid resin in the composition constituting the polylactic acid film of the present invention will be described later, a known polymerization method can be used, and a direct polymerization method from lactic acid, ring opening via lactide. Examples thereof include a polymerization method.

  The polylactic acid-based film of the present invention is a film comprising a composition containing a polylactic acid-based resin, and a composition containing 30% by mass or more of the above-described polylactic acid-based resin in 100% by mass of all components of the composition. Consists of. If the composition constituting the polylactic acid-based film contains less than 30% by mass of the polylactic acid-based resin, it is insufficient as a practical technology for plant-derived raw materials, which is the object of the present invention. Moreover, it is preferable that the polylactic acid-type film of this invention contains the subcomponent and organic lubricant which are mentioned later other than polylactic acid-type resin and a plasticizer so that it may mention later. From such a viewpoint, the composition constituting the polylactic acid-based film of the present invention preferably contains 30% by mass or more and 89% by mass or less of the polylactic acid-based resin described above.

  The polylactic acid-based film of the present invention can contain various resins other than the polylactic acid-based resin, but improves impact resistance and melt viscosity, and forms a stable bubble especially in the production process by the inflation method. In addition, for the purpose of improving the winding shape and the like, it is preferable that 5% by mass or more and 45% by mass or less of the subcomponents are included in 100% by mass of all the components constituting the polylactic acid film. When 100% by mass of the total component of the composition constituting the polylactic acid film contains 5% by mass or more of such subcomponents, the improvement effect is easily obtained mainly in terms of impact resistance. If it exists, moderate biodegradability can be provided.

  Here, the subcomponent means at least one resin selected from the group consisting of aliphatic aromatic polyesters, aliphatic polyesters, and polyolefins.

  Examples of the resin constituting the accessory component include polyglycolic acid, poly (3-hydroxybutyrate), poly (3-hydroxybutyrate · 3-hydroxyvalerate), polycaprolactone, ethylene glycol, 1,4- An aliphatic polyester composed of an aliphatic diol such as butanediol and an aliphatic dicarboxylic acid such as succinic acid or adipic acid, or an aliphatic polyester such as polybutylene succinate / terephthalate, polybutylene adipate / terephthalate, and an aromatic polyester. Polymers (aliphatic aromatic polyesters), low-density polyethylene, ethylene / propylene copolymers, ethylene / butene copolymers, and these are made of acrylic acid, methacrylic acid, maleic anhydride, fumaric acid and other With saturated carboxylic acid Polar group-containing polyolefin such as gender and acid-modified polyolefin resins, polyvinyl alcohol, and the like. Of these, polybutylene succinate, polybutylene succinate adipate, and polybutylene terephthalate adipate are particularly preferably used as subcomponents because they have a large improvement effect in both impact resistance and biodegradability.

  The composition constituting the polylactic acid-based film of the present invention preferably contains 5% by mass to 30% by mass of a plasticizer and 100% by mass to 25% by mass of the plasticizer in 100% by mass of the total components of the composition. More preferably, it is contained in an amount of not more than%. If the composition constituting the polylactic acid-based film contains less than 5% by mass of a plasticizer, sufficient flexibility may not be obtained when it is used as a film. In addition, when the composition constituting the polylactic acid-based film contains more than 30% by mass of a plasticizer, the film does not have sufficient stiffness and is inferior in handleability, inferior in strength and durability, and in practical use. When the plasticizer bleedout becomes large and lacks practicality, and it becomes difficult to give important shrinkage characteristics to obtain a good roll winding shape and unwinding properties described later. There is.

  As the plasticizer that can be used in the polylactic acid film of the present invention, those that are liquid at room temperature or those that are solid at room temperature can be used. For example, diethyl phthalate, dioctyl phthalate, phthalate Phthalic acid esters such as dicyclohexyl acid, aliphatic dibasic acid esters such as di-1-butyl adipate, di-n-octyl adipate, di-n-butyl sebacate, di-2-ethylhexyl azelate, Phosphoric acid esters such as diphenyl-2-ethylhexyl phosphate and diphenyloctyl phosphate, hydroxy polyvalent carboxylic acid esters such as tributyl acetylcitrate, tri-2-ethylhexyl citrate and tributyl acetylcitrate, acetylricinoleic acid Fatty acid esters such as methyl and amyl stearate; Polyhydric alcohol esters such as lysine triacetate and triethylene glycol dicaprylate, epoxy plasticizers such as epoxidized soybean oil, epoxidized linseed fatty acid butyl ester, and octyl epoxy stearate, polyesters such as polypropylene glycol sebacate A plasticizer, a polyalkylene ether type, an ether ester type, an acrylate type, etc. are mentioned, Among these, a mixture of two or more kinds of plasticizers is also included.

  Also, in agricultural applications, taking into account the possibility of residual undegraded products remaining in compost and farmland temporarily, plastics approved by the US Food Sanitation Agency (FDA), the Sanitation Council for Polyolefins (JHOSPA), etc. It is preferable that it is an agent. Examples of such plasticizers include triacetin, epoxidized soybean oil, epoxidized linseed oil, epoxidized linseed oil fatty acid butyl ester, adipic acid-based aliphatic polyester, acetyl citrate tributyl, acetyl ricinoleic acid ester, glycerin fatty acid ester, sucrose Examples thereof include fatty acid esters, sorbitan fatty acid esters, adipic acid dialkyl esters, bisalkyldiglycol adipates, and polyethylene glycols.

  Since the polylactic acid-based film of the present invention contains a polylactic acid-based resin, from the viewpoint of durability during storage before use, including suppression of bleed out of the plasticizer and blocking of the film, dimensional stability, For example, polyethylene glycol having a number average molecular weight of 1,000 or more is preferably solid at room temperature. From the same point of view, it is a block copolymer having a polyether-based segment and / or a polyester-based segment and a polylactic acid segment having a number average molecular weight of 1,200 or more and 10,000 or less in one molecule. Further preferred.

  Hereinafter, the above block copolymer (which has a polyether-based segment and / or a polyester-based segment, and has a number average molecular weight of 1,200 to 10 in one molecule, which is a preferred embodiment of the plasticizer used in the present invention. The block copolymer having a polylactic acid segment of 1,000 or less is referred to as “block copolymer plasticizer”).

  The mass ratio of the polylactic acid segment contained in the block copolymer plasticizer is preferably less than 50% by mass of the entire block copolymer plasticizer because a desired flexibility can be imparted with a smaller amount of addition. It is preferable from the viewpoint of bleed-out suppression that it is more than%. Further, the number average molecular weight of the polylactic acid segment in one molecule of the block copolymer plasticizer is preferably 1,200 or more and 10,000 or less. When the polylactic acid segment of the block copolymer plasticizer is 1,200 or more, sufficient affinity is produced between the block copolymer plasticizer and the polylactic acid resin, and a part of the segment Is incorporated into a crystal formed from a polylactic acid resin as a base material, thereby causing the plasticizer molecule to be anchored to the base material, and exerts a great effect on the bleed-out suppression of the block copolymer plasticizer. The number average molecular weight of the polylactic acid segment of the block copolymer plasticizer is preferably 2,000 or more and less than 6,000. The polylactic acid segment of the block copolymer plasticizer has an L-lactic acid-derived component of 95% by mass to 100% by mass, or a D-lactic acid-derived component of 95% by mass to 100% by mass. % Or less is preferable because bleeding out is particularly suppressed.

  The block copolymer plasticizer has a polyether-based segment and / or a polyester-based segment. When the block-copolymer plasticizer has a polyether-based segment, the polyester-based plasticizer is provided from the viewpoint of imparting desired flexibility with a smaller amount of addition. Polyether-based segments are preferred over segments. Moreover, as a polyether-type segment of a block copolymer plasticizer, it is more preferable to have the segment which consists of polyalkylene ether, and it is especially preferable to have the segment which consists of polyethyleneglycol. When the block copolymer plasticizer has a polyalkylene ether such as polyethylene glycol, polypropylene glycol, or polyethylene glycol / polypropylene glycol copolymer, particularly a polyether segment such as polyethylene glycol, it has an affinity for polylactic acid resin. Therefore, it is excellent in reforming efficiency, and is particularly preferable because a desired flexibility can be imparted by adding a small amount of a plasticizer.

  In addition, when the block copolymer plasticizer has a segment composed of a polyalkylene ether, the polyalkylene ether segment tends to be easily oxidized or thermally decomposed when heated at the time of molding or the like. It is preferable to use a hindered amine-based antioxidant or a phosphorus-based heat stabilizer in combination.

  When the block copolymer plasticizer has a polyester-based segment, polyglycolic acid, poly (3-hydroxybutyrate), poly (3-hydroxybutyrate-3hydroxyvalerate), polycaprolactone, or ethylene glycol Polyesters composed of aliphatic diols such as 1,4-butanediol and aliphatic dicarboxylic acids such as succinic acid and adipic acid are preferably used as the polyester-based segment. In addition, for reasons such as productivity and cost of the plasticizer, when it is used as either one of the polyether-based segment and the polyester-based segment, from the viewpoint that desired flexibility can be imparted by adding a smaller amount of the plasticizer. It is preferable to use a polyether-based segment.

  Furthermore, the number average molecular weight of the polyether segment and / or the polyester segment in one molecule of the block copolymer plasticizer is preferably 7,000 or more and less than 20,000. By setting the above range, the composition constituting the polylactic acid film has sufficient flexibility, and the melt viscosity of the composition is set to an appropriate level, and the film forming process such as the production process by the inflation method is performed. Sex can be stabilized.

  It is preferable that the composition which comprises the polylactic acid-type film of this invention contains 0.1 to 5 mass% of organic lubricants. In this case, blocking after winding can be favorably suppressed. In addition, problems such as a decrease in melt viscosity and deterioration of workability due to excessive addition of an organic lubricant, or poor appearance such as bleed out and haze up when formed into a film are less likely to occur.

  Examples of organic lubricants include liquid paraffins, natural paraffins, synthetic paraffins, aliphatic hydrocarbons such as polyethylene, stearic acid, lauric acid, hydroxystearic acid, fatty castors such as hard castor oil, stearic acid amide, oleic acid amide, Fatty acid amides such as erucic acid amide, lauric acid amide, ethylene bis stearic acid amide, ethylene bis oleic acid amide, ethylene bis lauric acid amide, fatty acid metal salts such as aluminum stearate, lead stearate, calcium stearate, magnesium stearate , Fatty acid (partial) esters of polyhydric alcohols such as glycerin fatty acid esters and rubitan fatty acid esters, long chain fatty acid esters such as long chain ester waxes such as butyl stearate and montan wax And the like. Among these, stearic acid amide and ethylene bis-stearic acid amide, which are easy to obtain an effect in a small amount due to appropriate compatibility with polylactic acid, are preferable.

  In the composition which comprises the polylactic acid-type film of this invention, you may contain components other than having mentioned above in the range which does not impair the effect of this invention. For example, known antioxidants, UV stabilizers, anti-coloring agents, matting agents, deodorants, flame retardants, weathering agents, antistatic agents, antioxidants, ion exchange agents, crystal nucleating agents, coloring pigments, etc. Alternatively, inorganic fine particles, organic particles, and organic lubricants may be added as necessary as a lubricant.

Examples of the antioxidant include hindered phenols and hindered amines. Color pigments include inorganic pigments such as carbon black, titanium oxide, zinc oxide, iron oxide, cyanine, styrene, phthalocyanine, anthraquinone, perinone, isoindolinone, quinophthalone, and quinocridone. Organic pigments such as thioindigo can be used.

  Moreover, when adding particles for the purpose of improving slipperiness and blocking resistance, for example, inorganic particles include silicon oxide such as silica, various carbonates such as calcium carbonate, magnesium carbonate, and barium carbonate, Various sulfates such as calcium sulfate and barium sulfate, various composite oxides such as kaolin and talc, various phosphates such as lithium phosphate, calcium phosphate and magnesium phosphate, various oxides such as aluminum oxide, titanium oxide and zirconium oxide Fine particles made of various salts such as lithium fluoride can be used.

  As the organic particles, fine particles made of calcium oxalate, terephthalate such as calcium, barium, zinc, manganese, magnesium, or the like are used. Examples of the crosslinked polymer particles include fine particles made of a vinyl monomer such as divinylbenzene, styrene, acrylic acid or methacrylic acid, or a copolymer. In addition, organic fine particles such as polytetrafluoroethylene, benzoguanamine resin, thermosetting epoxy resin, unsaturated polyester resin, thermosetting urea resin, and thermosetting phenol resin are also preferably used.

  The average particle diameter of both inorganic particles and organic particles is not particularly limited, but is preferably 0.01 to 10 μm, more preferably 0.1 to 5 μm, and particularly preferably 1 to 4 μm. The addition amount of both inorganic particles and organic particles is not particularly limited, but is preferably 0.1% by mass or more and 5% by mass or less, and 2.5% by mass or more and 5% by mass or less of the polylactic acid film of the present invention. It is particularly preferred. When the average particle size is less than 0.01 μm and / or the addition amount is less than 0.1% by mass, problems such as blocking of the film may occur, and the average particle size exceeds 10 μm, and If the added amount exceeds 5% by mass, the productivity may be deteriorated.

  The polylactic acid film of the present invention is preferably a film having a thickness of 10 μm or more and 120 μm or less. If the thickness is less than 10 μm, the film may not have sufficient stiffness and may be inferior in handleability, and it may be difficult to impart a good roll form and unwinding property. In addition, when the thickness exceeds 120 μm, sufficient flexibility cannot be obtained, such as agricultural and forestry applications such as agricultural multi-film and pine worm fumigation sheets, garbage bags, compost bags, or various packaging applications. In some cases, the handling becomes inferior. In particular, in the production process by the inflation method, the bubbles are likely to become unstable due to the weight of the bubbles, and it may be difficult to impair the flatness and give a good roll winding shape.

  Next, the method for producing the polylactic acid film of the present invention will be specifically described with respect to the case where a polylactic acid resin is used as a preferred example.

  The polylactic acid resin in the present invention can be obtained, for example, by the following method. As a raw material, a lactic acid component of L-lactic acid or D-lactic acid is mainly used, and a hydroxycarboxylic acid other than the lactic acid component described above can be used in combination. Further, a cyclic ester intermediate of hydroxycarboxylic acid, for example, lactide, glycolide, etc. can be used as a raw material. Furthermore, dicarboxylic acids and glycols can also be used.

  The polylactic acid resin can be obtained by a method of directly dehydrating and condensing the raw materials or a method of ring-opening polymerization of the cyclic ester intermediate. For example, in the case of producing by direct dehydration condensation, lactic acid or lactic acid and hydroxycarboxylic acid are preferably subjected to azeotropic dehydration condensation in the presence of an organic solvent, particularly a phenyl ether solvent, and particularly preferably a solvent distilled by azeotropic distillation. A polymer having a high molecular weight can be obtained by polymerizing by a method in which water is removed from the solvent and the solvent is brought into a substantially anhydrous state and returned to the reaction system.

  It is also known that a high molecular weight polymer can be obtained by subjecting a cyclic ester intermediate such as lactide to ring-opening polymerization under reduced pressure using a catalyst such as tin octylate. At this time, a method for adjusting the conditions for removing moisture and low molecular weight compounds during heating and refluxing in an organic solvent, a method for suppressing the depolymerization reaction by deactivating the catalyst after completion of the polymerization reaction, and a method for heat-treating the produced polymer Can be used to obtain a polymer with a small amount of lactide.

  Next, in one of the preferred embodiments of the present invention, a polylactic acid segment having a number average number molecular weight of 1,200 or more and 10,000 or less is used in one molecule, and a polyether segment and / or a polyester segment. A more specific example of the block copolymer plasticizer having the following will be described.

A polyethylene glycol having a hydroxyl group at both ends (hereinafter, polyethylene glycol is referred to as PEG) is prepared. The number average molecular weight of PEG having hydroxyl ends at both ends (hereinafter, the number average molecular weight of _PEG is referred to as _MPEG ) is usually calculated from the hydroxyl value determined by a neutralization method or the like in the case of a commercially available product. In a system in which lactide w _A parts by mass are added to w _B parts by mass of PEG having hydroxyl groups at both ends, lactide undergoes ring-opening addition polymerization at both hydroxyl groups of PEG and is sufficiently reacted. A block copolymer of type (A) -PEG (B) -PLA (A) can be obtained (PLA here indicates polylactic acid). This reaction is performed in the presence of a catalyst such as tin octylate as necessary. The number average molecular weight of one polylactic acid segment of the plasticizer made of this block copolymer can be substantially determined as (1/2) × (w _A / w _B ) × M _PEG . The mass percentage of the total block copolymer plasticizer of the polylactic acid segment component can be substantially determined as _{100 × w A / (w A} + w B)%. Furthermore, the mass ratio of the plasticizer component excluding the polylactic acid segment component to the entire block copolymer plasticizer can be determined to be substantially 100 × w _B / (w _A + w _B )%.

  Block copolymer plasticizer contains a large amount of unreacted PEG, reactants with PEG whose terminal polylactic acid segment number average molecular weight is less than 1,200, by-products such as lactide oligomers, impurities, etc. If included, it is preferable to remove them, for example, by the following purification method. The synthesized block copolymer plasticizer is uniformly dissolved in an appropriate good solvent such as chloroform, and then an appropriate poor solvent such as a water / methanol mixed solution or diethyl ether is added dropwise. Alternatively, precipitation is performed by adding a good solvent solution in a large excess of poor solvent, and the solvent is evaporated after separating the precipitate by centrifugation or filtration. After immersing the block copolymer plasticizer in water, the mixture is heated to 50 to 90 ° C. and stirred as necessary, and then the organic phase containing the block copolymer plasticizer is extracted and dried to remove water. The purification method is not limited to the above, and the above operation may be repeated a plurality of times as necessary. Removal of by-products such as lactide oligomers can prevent a decrease in viscosity when a polylactic acid resin composition is obtained, and the melt viscosity of the composition is set to an appropriate level to stabilize processing. It is also preferable because it can be performed.

When a plasticizer of a PLA (A) -PEG (B) -PLA (A) type block copolymer is prepared by the method described above, the molecular weight of one polylactic acid segment of the prepared plasticizer is as follows: It can be determined by the method. That is, based on a chart obtained by ¹ H-NMR measurement using a deuterated chloroform solution of a block copolymer plasticizer, {I _PLA × (molecular weight of polylactic acid monomer unit) / (number of polylactic acid segments) } / {I _PEG × (molecular weight of PEG monomer unit) / (number of chemically equivalent protons)} × M _PEG . That is, when a PLA (A) -PEG (B) -PLA (A) type block copolymer plasticizer is prepared, {I _PLA × 72/2} / {I _PEG × 44/4} × M _PEG . However, I _PEG is the signal integral intensity derived from the hydrogen of the methylene group of the PEG main chain part, and I _PLA is the signal integral intensity derived from the hydrogen of the methine group of the PLA main chain part. When the reaction rate of lactide during the synthesis of block copolymer plasticizer is sufficiently high and almost all lactides are synthesized under the condition of ring-opening addition to the PEG end, it is often obtained by ¹ H-NMR measurement. The molecular weight of one polylactic acid segment of the plasticizer is preferably determined by the above method based on the chart obtained.

  In the present invention, in obtaining a composition containing a polylactic acid-based resin and a plasticizer, an aliphatic aromatic polyester, or other components (composition constituting the polylactic acid-based film of the present invention), each component is a solvent. It is possible to produce a composition by removing the solvent after uniformly mixing the solution dissolved in the solution, but it is a practical production method that does not require steps such as dissolution of the raw material in the solvent, solvent removal, It is preferable to employ a melt-kneading method for producing a composition by melt-kneading each component. The melt kneading method is not particularly limited, and a commonly used known mixer such as a kneader, roll mill, Banbury mixer, single-screw or twin-screw extruder can be used. Among these, from the viewpoint of productivity, it is preferable to use a single screw or twin screw extruder.

  The mixing order is not particularly limited, for example, after dry blending a polylactic acid-based resin and a plasticizer, a method of using a melt kneader, or after preparing a master batch in which a polylactic acid-based resin and a plasticizer are previously melt-kneaded, Examples thereof include a method of melt-kneading the master batch with a polylactic acid resin and the other components described above. Further, if necessary, a method of melt-kneading other components at the same time, or preparing a master batch in which a polylactic acid-based resin and other additives are melt-kneaded in advance, the master batch, the polylactic acid-based resin, and a plasticizer component You may use the method of melt-kneading. Moreover, when adding components, such as a plasticizer liquid at normal temperature, it can also add from the raw material supply hole vent hole of an extruder using a metering pump separately from a solid component at normal temperature.

  The temperature at the time of melt kneading is preferably in the range of 150 ° C. to 240 ° C., and more preferably in the range of 200 ° C. to 220 ° C. from the viewpoint of preventing the deterioration of the polylactic acid resin.

  The polylactic acid-based film of the present invention is a method for producing an existing film such as a known inflation method, T-die casting method, or biaxial stretching method after T-die casting, using the composition obtained by the above-described method, for example. Can be obtained.

  In producing the polylactic acid-based film of the present invention, for example, when the composition obtained by the above-described method is once chipped, melt-kneaded again and extruded and formed into a film, the chip is heated at 60 to 110 ° C. It is preferable that the moisture content of the composition is 1200 ppm or less by drying for 6 hours or more. Furthermore, it is preferable to reduce the lactide content in the composition by vacuum drying under a high vacuum with a degree of vacuum of 10 Torr or less. By reducing the moisture content of the composition to 1200 ppm or less and reducing the lactide content, hydrolysis during melt-kneading can be prevented, thereby preventing molecular weight reduction, the melt viscosity is set to an appropriate level, and the film-forming process is stabilized. It is also preferable because it can be made. From the same point of view, when chipping or melt extrusion / film formation is performed once, melt extrusion is performed while removing volatiles such as moisture and low molecular weight substances using a twin-screw extruder with a vent hole. It is preferable.

  The method for producing the polylactic acid film of the present invention is preferably an inflation method. In the case of producing by an inflation method, it is easy to suppress molecular orientation, and to easily give the elongation necessary for practicality of the multifilm, so-called elongation. In addition, since it is easy to suppress oriented crystallization, it is easy to obtain a film having an appropriate potential shrinkage stress even at room temperature, which is a feature of the polylactic acid film of the present invention. When manufacturing by the inflation method, for example, the composition prepared by the method as described above is melt-extruded with a twin-screw extruder with a vent hole and led to an annular die, and extruded from the annular die and supplied with dry air inside. Then, it is formed into a balloon shape (bubble), air-cooled and solidified uniformly with an air ring, taken up at a specified take-up speed while being folded flat with a nip roll, and then cut at both ends or one end as necessary. Take it.

  In this case, depending on the discharge amount from the annular die, the take-up speed of the nip roll, and the bubble blow ratio, the thickness is usually adjusted to be 10 μm or more and 120 μm or less, but in order to increase the thickness accuracy and uniformity, The annular die is preferably a spiral type.

  Moreover, although the extrusion temperature of the composition containing polylactic acid-type resin etc. is the range of 150-240 degreeC normally, thickness accuracy and a uniformity are improved and also a favorable roll winding form and unwinding property are provided. For this purpose, the temperature of the annular die is important, and the temperature of the annular die is in the range of 150 to 190 ° C, preferably 150 to 170 ° C. If the temperature of the annular die is less than 150 ° C., the temperature at which the composition is extruded is too low, the molding behavior at the time of blow-up immediately after discharge becomes uneven, the thickness accuracy deteriorates, and the winding shape becomes poor. When a film is formed because the stress at the time of up is too high, the heat shrinkage rate is high, and the winding shape is further deteriorated by so-called winding tightening over time. On the other hand, when the temperature of the annular die exceeds 190 ° C., the viscosity of the composition is too low, the thickness accuracy is deteriorated and the winding shape is poor, and the bubble formation itself tends to be unstable. From the same viewpoint, the temperature of the annular die is more preferably 160 to 170 ° C.

  The bubble blow ratio depends on the relationship between the discharge rate and the take-up speed of the nip roll, but the film may be too anisotropic if it is too low or too high. Tends to be unstable, and it is usually preferred to be in the range of 2.0 to 4.0.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by a following example.
[Measurement and evaluation method]
(1) Maximum value of molecular weight peak in molecular weight distribution of polylactic acid based resin WATERS differential refractometer WATERS410 is used as a detector, MODEL510 high performance liquid chromatography is used as a pump, ShodexGPC HFIP-806M and Shodex GPC HFIP-LG are used as columns. GPC measurement was carried out using those connected in series, and the maximum value of the molecular weight peak was obtained from the molecular weight distribution obtained by standard polystyrene conversion. The measurement conditions were a flow rate of 0.5 mL / min, a solution obtained by dissolving a film in chloroform as a solvent and removing insolubles was used as a solution, and 0.1 mL of a solution having a sample concentration of 1 mg / mL was injected.
(2) Amount of component (mass%) of polylactic acid resin having a molecular weight of 100,000 or more
A region having a molecular weight of 3,000 or less is excluded from the molecular weight distribution obtained by the same method as the method for obtaining the maximum value of the molecular weight peak, and the molecular weight is 100,000 or more in the chart area of the region having a molecular weight exceeding 3,000. The ratio of the chart area was calculated as the component amount (% by mass) of the polylactic acid resin having a molecular weight of 100,000 or more.
(3) Component amount (mass%) of polylactic acid resin having a molecular weight of less than 100,000
From the molecular weight distribution obtained by the same method as the method for obtaining the maximum value of the molecular weight peak, the region having a molecular weight of 3,000 or less is excluded, and the molecular weight of the region exceeding the molecular weight of 3,000 is less than 100,000. The ratio of the chart area was calculated as the component amount (% by mass) of the polylactic acid resin having a molecular weight of less than 100,000.
(4) Film thickness (μm)
In accordance with JIS B7503, the thickness of 10 points was measured using a dial gauge, and the average thickness was defined as the film thickness.
(5) Expandability When confirming the expandability as an agricultural multi-film application, use a tactor with a maltator in a field in Nagano Prefecture (soil type: surface corrosive black soil, temperature: 10 ° C). Stretching was performed simultaneously with the standing, and the shape of the ridge was a fold having a ridge width of 60 cm and a ridge height of 35 cm having a semicircular cross section. A 50-m stretch was performed, and the stretchability was determined according to the following criteria. The field where the extension test was performed was slightly clayey and contained many relatively hard soil blocks with a diameter of 3 cm or more.

Also, when confirming spreadability as a sheet for fumigation of pine worms, 30 timbers trimmed to a length of 1 m are stacked up to a height of 1 m and a width of 3 m at a pine cutting site in Fukushima Prefecture. This was coated in an atmosphere at a temperature of 5 ° C., and the stretchability was determined according to the following criteria.
○: When expanding, it can be expanded without any problem.
Δ: Partially broken at a frequency of not more than twice during stretching, but no problem in practical use.
×: Not applicable to ○ or △.
(6) Biodegradability The same stretch as the above confirmation of the stretchability was performed, and the biodegradability was determined according to the following criteria.
○: After spreading, the film form is maintained for 3 months for agricultural multi-film use and for 2 weeks for pine worm fumigation sheet use. The film is sufficiently decomposed to expose field soil (for agricultural multi-film use) or wood (for pine worm fumigation sheet use).
Δ: After stretching, perforation occurs in 3 or less places for agricultural multi-film use for 3 months and for pine worm fumigation sheet use for 2 weeks, but there is no problem in practical use. Or, when one year has passed since the spreading, pieces of film that have not been completely decomposed (both less than 20 cm ² ) are scattered around, but field soil (for multi-film use for agriculture) or wood (pine worms) Fumigation sheet use) is sufficiently exposed, and there is no problem in practical use.
X: After spreading, the film shape cannot be maintained due to the film breaking or the like in 3 months for agricultural multi-film use and for 2 weeks for pine worm fumigation sheet use, or at 4 or more places Holes are generated in places, which is not practical for the application. Or, when 1 year has passed since the expansion, undecomposed film pieces (20 cm ² or more) are scattered around and the landscape is poor, or field soil (for agricultural multi-film use) / wood (pine worms) Fumigation sheet use) is not sufficiently exposed and is not practical as such use.
(7) Manufacturability The following criteria were used to determine manufacturability when manufacturing films.
○: Bubbles do not become unstable and stable production is possible.
Δ: Film width variation of 1 cm or less is confirmed, but stable production is possible.
X: The film width fluctuates due to unstable bubbles, and stable production cannot be performed.
(8) Comprehensive evaluation Judgment was made on the basis of the following criteria from the results of determination of stretchability, biodegradability and manufacturability.
◯: All items are judged as “◯”, and can be preferably used as an agricultural multi-film application or a pine worm fumigation sheet application.
△: The item is judged as “△” in one item or two items, but the decision in other items is “◯”, and it is practically used as an agricultural multi-film use or a pine worm fumigation sheet use. no problem.
×: “△” is determined for all items, or “×” is determined for one or more items, and it is difficult to use as an agricultural multi-film use or a pine worm fumigation sheet use. is there.
[Polylactic acid resin used]
(1) PL1
Polylactic acid (trade name “NatureWorks 4060D” (manufactured by NatureWorks) (weight average molecular weight: 180,000, L-form / D-form: 88/12))
(2) PL2
Polylactic acid (manufactured by NatureWorks, trade name “NatureWorks4042D” (weight average molecular weight: 180,000, L-form / D-form: 96/4))
(3) PL3
A polylactic acid-based sheet (trade name “Ecodia # 1000 1F01CA” (manufactured by Toray Industries, Inc.) (polylactic acid content: ≧ 98%) is made into a sheet pulverizer (trade name “SW Series pulverizer SW-450, manufactured by Otada Seisakusho Co., Ltd.). )) To obtain a polylactic acid resin PL3 (weight average molecular weight: 130,000).
(4) PL4
The above PL3 was melt extruded using a single screw extruder with a vent hole (Toshiba Machine Co., Ltd., trade name “SE-50CV”, processing conditions: 200 ° C.), and the strand extruded from the die head was put into a water tank (20 ° C.). Then, it was cooled and solidified, and cut into a length of 2 mm to obtain a polylactic acid resin PL4. (Weight average molecular weight: 90,000)
(5) PL5
The above PL3 is granulated with a granulator (Fuji Steel Co., Ltd., trade name “Fuji Curl Pelletizer 33-390”, processing conditions: die temperature 90 ° C., pellet temperature 70 ° C.), and polylactic acid resin PL5 Got. (Weight average molecular weight: 110,000)
(6) PL6
Polylactic acid (manufactured by NatureWorks, trade name “NatureWorks4032D” (weight average molecular weight: 180,000, L-form / D-form: 99/1))
[Subcomponents used]
(1) PBAT
Polybutylene terephthalate adipate (BASF, trade name “ECOFLEX”)
(2) PBSA
Polybutylene succinate adipate (made by Showa Polymer Co., Ltd., trade name “Bionore # 3001”)
(3) PBS
Polybutylene succinate (trade name “GS-Pla AZ91TN” manufactured by Mitsubishi Chemical Corporation)
(4) DO
Modified polyolefin (trade name “Admer SF731” manufactured by Mitsui Chemicals, Inc.)
[Plasticizer used]
(1) PS1
By mixing 62 parts by mass of polyethylene glycol having a number average molecular weight of 8,000, 38 parts by mass of L-lactide and 0.1 part by mass of tin octylate and polymerizing at 160 ° C. for 3 hours in a nitrogen atmosphere, both ends of polyethylene glycol are obtained. A plasticizer PS1 having a polylactic acid segment having a number average molecular weight of 2,500 was obtained.
(2) PS2
By mixing 31 parts by mass of polyethylene glycol having a number average molecular weight of 4,000, 69 parts by mass of L-lactide and 0.1 part by mass of tin octylate and polymerizing at 160 ° C. for 3 hours in a nitrogen atmosphere, both ends of polyethylene glycol are obtained. A plasticizer PS2 having a polylactic acid segment having a number average molecular weight of 5,000 was obtained.
(3) PS3
Acetyltributyl citrate (Morimura Corporation, trade name “Citroflex A-4”)
(4) PS4
Polyethylene glycol (trade name “PEG-10000”, manufactured by Sanyo Chemical Industries)
[Additives used]
(1) SL
Stearic acid amide (manufactured by NOF Corporation, trade name “Alflow S-10”)
(2) PT1
Calcium carbonate (manufactured by Maruo Calcium Co., Ltd., trade name "Caltex R")
(3) PT2
Talc (Nippon Talc Co., Ltd., trade name "SG-95")
(4) CB
Carbon black (Mitsubishi Chemical Corporation, trade name “Mitsubishi Carbon Black # 30”)
(5) IO
Ferric oxide (trade name “Bayferox 686G” manufactured by Ozekisha)
[Creation of polylactic acid film]
Example 1
Polylactic acid PL1 28.6% by mass, polylactic acid PL2 7.1% by mass, polylactic acid resin PL3 35.7% by mass, plasticizer PS1 24.3% by mass, additive SL 1.4% by mass %, Additive PT1 2.9% by weight of the mixture was fed to a twin screw extruder with a cylinder diameter of 190 ° C. and a screw diameter of 44 mm with a vacuum vent. A composition 1 was obtained.

  The composition 1 was dried with dehumidified hot air at a temperature of 100 ° C. and a dew point of −25 ° C. for 10 hours, and finally the composition shown in Table 1 as a mixture of 70% by mass of composition 1 and 30% by mass of the accessory component PBAT. The product is supplied to a single screw extruder with a screw diameter of 65 mm at an extruder cylinder temperature of 190 ° C. and is blown from a spiral annular die with a diameter of 250 mm, a lip clearance of 1.3 mm and a temperature of 165 ° C. at a blow ratio of 3.4. , Rolled up with a nip roll above the die, pulled up at 30 m / min, cut at both ends with an edge cutter, and cut into two pieces, each wound with a 1350 mm wide film with a winder I took it. A final thickness of 20 μm was obtained by adjusting the discharge amount, and the evaluation results of the obtained film are shown in Table 1.

The obtained polylactic acid-based film of the present invention is capable of stable production, and exhibits excellent properties in terms of stretchability and biodegradability when used as an agricultural multi-film application. It was a film which can be preferably used as a multi-film.
(Example 2)
Polylactic acid PL1 is 41.7% by mass, polylactic acid resin PL3 is 50% by mass, additive SL is 1.7% by mass, additive PT2 is 3.3% by mass, and additive CB is 3.3% by mass. The mixture was chipped by the same method as in Example 1 to obtain a composition 2. This composition 2 was dried by the same method as in Example 1, and finally the composition shown in Table 1 was obtained as a mixture of 60% by mass of Composition 2 and 40% by mass of the accessory component PBSA. Table 1 shows the evaluation results of the film obtained by the above method to obtain a film having a final thickness of 25 μm.

The obtained polylactic acid-based film of the present invention can be stably produced, and exhibits excellent properties in terms of stretchability when used as an agricultural multi-film application. Although the decomposition was delayed in terms of biodegradability, there was no problem in practical use, and the film could be sufficiently used as an agricultural multi-film.
(Example 3)
Polylactic acid PL1 61.4% by mass, polylactic acid resin PL4 9.8% by mass, plasticizer PS1 24.3% by mass, additive PT1 4.3% by mass, additive IO 0.2% by mass % Of the mixture was chipped in the same manner as in Example 1 to obtain Composition 3. This composition 3 was dried by the same method as in Example 1, and finally the composition shown in Table 1 was prepared as a mixture of 70% by mass of composition 3 and 30% by mass of the accessory component PBS. From a spiral annular die of 1.5 mm and temperature of 165 ° C., extruded upward in a bubble shape at a blow ratio of 4.25, air-cooled with a cooling ring, taken up at 7 m / min while folding with a nip roll above the die, one side A film having a final thickness of 120 μm was obtained in the same manner as in Example 1 except that the edge of the film was cut with an edge cutter and the film having a width of 4000 mm was wound with a winder in a state of being folded to a width of 2000 mm. . The evaluation results of the obtained film are shown in Table 1.

The obtained polylactic acid-based film of the present invention can be stably produced, and exhibits excellent properties in terms of stretchability when used as a pine worm fumigation sheet. Although the degradation was delayed in terms of biodegradability, there was no problem in practical use, and the film could be used satisfactorily as a pine worm fumigation sheet.
Example 4
Example of a mixture of 20% by mass of polylactic acid PL1, 69.8% by mass of polylactic acid resin PL5, 5% by mass of plasticizer PS1, 5% by mass of additive PT2, and 0.2% by mass of additive IO A chip was obtained in the same manner as in Example 1 to obtain Composition 4. This composition 4 was dried by the same method as in Example 1, and finally the composition shown in Table 1 as a mixture of 60% by mass of Composition 3 and 40% by mass of the accessory component PBAT was obtained. By this method, a film having a final thickness of 100 μm was obtained. The evaluation results of the obtained film are shown in Table 1.

The obtained polylactic acid-based film of the present invention can be stably produced, and exhibits excellent properties in terms of stretchability and biodegradability when used as a pine worm fumigation sheet. The film can be preferably used as a pine worm fumigation sheet.
(Example 5)
A film having a final thickness of 20 μm was obtained in the same manner as in Example 1 except that the mixture having the composition shown in Table 1 was directly supplied to a twin-screw extruder with a vent hole having a screw diameter of 65 mm and an extruder cylinder temperature of 190 ° C. It was. The evaluation results of the obtained film are shown in Table 1.

The obtained polylactic acid-based film of the present invention has a film width fluctuation of 1 cm or less during production, but it can be manufactured in a substantially stable manner and is biodegradable when used as an agricultural multi-film application. The characteristic which was excellent in the property side was shown. In terms of stretchability, the film may be partially broken at a frequency of 2 times or less during 50 m stretch, but it is a level that is not a problem in practical use and was a film that can be sufficiently used as an agricultural multi-film. .
(Example 6)
A film having a final thickness of 15 μm was obtained in the same manner as in Example 5 except that the mixture having the composition shown in Table 1 was used. The evaluation results of the obtained film are shown in Table 1.

The obtained polylactic acid-based film of the present invention can be stably produced, and when used as an agricultural multi-film, exhibits excellent characteristics in terms of biodegradability. In terms of stretchability, the film may be partially broken at a frequency of 2 times or less during 50 m stretch, but it is a level that is not a problem in practical use and was a film that can be sufficiently used as an agricultural multi-film. .
(Example 7)
A film having a final thickness of 100 μm was obtained in the same manner as in Example 3 except that the mixture having the composition shown in Table 1 was directly supplied to a twin-screw extruder with a vent hole having a screw diameter of 65 mm and an extruder cylinder temperature of 190 ° C. It was. The evaluation results of the obtained film are shown in Table 1.

The obtained polylactic acid-based film of the present invention can be stably produced, and when used as a pine worm fumigation sheet, 30 pieces of wood trimmed to a length of 1 m in terms of stretchability. May be partially broken twice or less when covering the timber piled up to a height of 1 m and a width of 3 m, but there is no problem in terms of practical use. When a year has passed, pieces of film that are not completely decomposed (both less than 20 cm ² ) are scattered around, but the wood is sufficiently exposed and is a level that is not a problem in practical use. It was a film that could be used satisfactorily as an insect fumigation sheet.
(Example 8)
A film having a final thickness of 100 μm was obtained in the same manner as in Example 7 except that the mixture having the composition shown in Table 1 was used. The evaluation results of the obtained film are shown in Table 1.

The obtained polylactic acid-based film of the present invention can be stably produced, and exhibits excellent properties in terms of stretchability and biodegradability when used as a pine worm fumigation sheet. The film can be preferably used as a pine worm fumigation sheet.
(Comparative Example 1)
A film having a final thickness of 20 μm was obtained in the same manner as in Example 1 using polylactic acid PL1 (100 mass%). The evaluation results of the obtained film are shown in Table 2.

When the obtained polylactic acid-based film is used for agricultural multi-film applications, it cannot be used as agricultural multi-films because it does not decompose even after 1 year from spreading and the field soil is not exposed. It was.
(Comparative Example 2)
A film having a final thickness of 20 μm was obtained in the same manner as in Example 5 except that the mixture having the composition shown in Table 2 was used. The evaluation results of the obtained film are shown in Table 2.

When the obtained polylactic acid-based film is used as an agricultural multi-film application, when 1 year has passed since stretching, undecomposed film pieces (both 20 cm ² or more) are scattered around and the landscape is bad, Moreover, since the field soil was not sufficiently exposed, it could not be used as an agricultural multi-film.
(Comparative Example 3)
A film having a final thickness of 100 μm was obtained in the same manner as in Example 7 except that the mixture having the composition shown in Table 2 was used. The evaluation results of the obtained film are shown in Table 2.

When the obtained polylactic acid-based film is used as a pine worm fumigation sheet, it was not decomposed even after 1 year from the expansion and the wood was not exposed. I couldn't.
(Comparative Example 4)
A film having a final thickness of 20 μm was obtained in the same manner as in Example 5 except that the mixture having the composition shown in Table 2 was used. The evaluation results of the obtained film are shown in Table 2.
The resulting polylactic acid-based film has a film width variation of 1 cm or less during production, and when the obtained polylactic acid-based film is used as an agricultural multi-film, the stretchability is 50 m. In this case, some breakage may occur at a frequency of 2 times or less, and in terms of biodegradability, holes were generated at 3 positions within 3 months after the expansion. From these practicality evaluations, the obtained polylactic acid film could not be used practically for agricultural multi-film applications.
(Comparative Example 5)
Except for using the mixture having the composition shown in Table 2, an attempt was made to obtain a film having a final thickness of 20 μm by the same method as in Example 5, but the film width fluctuated, for example, the bubbles became unstable. Stable production was not possible.
(Comparative Example 6)
Except for using a mixture having the composition shown in Table 2, an attempt was made to obtain a film having a final thickness of 20 μm by the same method as in Example 7, but the film width fluctuated, for example, the bubbles became unstable. Stable production was not possible.

Claims (8)

A film comprising a composition containing a polylactic acid-based resin,
The composition contains 30% by mass or more of a polylactic acid resin in 100% by mass of all the components of the composition,
In the molecular weight distribution, the polylactic acid-based resin has at least one maximum value of molecular weight peak in a region having a molecular weight of 100,000 or more, and has at least one maximum value of molecular weight peak in a region having a molecular weight of less than 100,000. A polylactic acid film characterized by being a thing.   In 100% by mass of the polylactic acid-based resin, 5 polylactic acid-based resins having 30 to 95% by mass of a polylactic acid resin having a molecular weight of 100,000 or more in the molecular weight distribution and having a molecular weight of less than 100,000 in the molecular weight distribution are 5 The polylactic acid-based film according to claim 1, wherein the polylactic acid film is contained in an amount of not less than 70% by mass and not more than 70% by mass. In 100% by mass of all the components of the composition, 5% by mass or more and 45% by mass or less of subcomponents are included,
The polylactic acid film according to claim 1 or 2, wherein the subcomponent is at least one resin selected from the group consisting of aliphatic aromatic polyesters, aliphatic polyesters, and polyolefins.   The polylactic acid according to claim 3, wherein the subcomponent is at least one resin selected from the group consisting of polybutylene succinate, polybutylene succinate adipate, and polybutylene terephthalate adipate. Film.   5. The polylactic acid-based film according to claim 1, wherein a plasticizer is contained in an amount of 5% by mass to 30% by mass in 100% by mass of all components of the composition.   6. The maximum value of at least one peak in a molecular weight distribution of less than 100,000 in the molecular weight distribution of the polylactic acid resin is derived from recycled polylactic acid resin. The polylactic acid film described in 1.   An agricultural multi-film comprising the film according to claim 1.   A sheet for fumigation of pine worms comprising the film according to claim 1.