KR101970847B1 - Biodegradable film - Google Patents

Abstract

Disclosed is a biodegradable film containing a lactic acid resin (A) and a biodegradable resin (B) other than the lactic acid resin (A), wherein the biodegradable resin (B) (A) is dispersed in a long oval phase in the longitudinal direction of the film or in a long layer in the longitudinal direction of the film in a continuous phase containing the lactic acid resin (A) and the lactic acid resin in total 100% by mass of the biodegradable resin (B), the lactic acid resin (a) content (mass%) of P _a, the biodegradable resin (B) content of the (% by mass) P _B, the thickness of the dispersed phase of the (nm) is W _A , and the thickness (nm) of the continuous film is W _B , the biodegradable film satisfies the following formula.
W _A / W _B? 2.0P _A / P _B
The present invention provides a biodegradable film having excellent flexibility, endurance and transparency, excellent biomass property, and particularly exhibiting good effects in an inflation film forming method.

Description

Biodegradable film {BIODEGRADABLE FILM}

The present invention relates to a biodegradable film which is excellent in flexibility, endurance and transparency, is excellent in biomass property, and particularly exhibits a good effect in an inflation film forming method.

In recent years, the problem of global warming caused by the increase of carbon dioxide due to incineration has been attracting attention. As countermeasures against the former, various biodegradable resins, as a countermeasure against the latter, resins containing biomass (plant-derived raw material) which do not give new carbon dioxide load to the atmosphere even when incinerated are actively researched and developed. Polylactic acid which satisfies both of them and is comparatively advantageous in terms of cost has attracted attention. Attempts to apply polylactic acid to soft film applications typified by polyolefins such as polyethylene have been lacking in flexibility and impact resistance, and therefore various attempts have been made to improve these properties and put them to practical use.

[Patent Literature]

For example, Patent Document 1 discloses a film comprising a polylactic acid, a copolymer of a biodegradable aliphatic polyester having a glass transition temperature of 0 DEG C or lower and an aromatic copolymer polyester, a plasticizer, and a resin composition comprising an inorganic filler as constituent components . Patent Document 2 discloses a film including a composition containing a polylactic acid resin and a plasticizer, and defining elongation, thickness, and heat shrinkage ratio. Patent Document 3 discloses a biodegradable resin composition and film in which a diisocyanate is added to a mixture of polyester containing adipic acid, terephthalic acid, butanediol, and polylactic acid.

(Patent Document 1) Japanese Patent Laid-Open No. 2002-327107

(Patent Document 2) JP-A-2009-138085

(Patent Document 3) Japanese Patent No. 3411289

The above-mentioned Patent Document 1 discloses improvement of the flexibility and impact resistance of the film, but does not disclose any technique for improving the resistance to tearing and transparency at all. In fact, the tear resistance and transparency of the film are insufficient.

In addition, although Patent Document 2 mentioned above discloses improvement of the flexibility and impact resistance of the film, no technology for improving the thermostability has been disclosed at all, and the thermostability of the film is actually insufficient.

Further, in the above-described Patent Document 3, it is described that both of the biodegradability and the mechanical property can be optimized according to the application, but the disclosed technology is insufficient in transparency and endurance.

As described above, various studies have been made on a technique relating to a biodegradable film having excellent flexibility, excellent thermostability and transparency, excellent biomass property, and particularly exhibiting a good effect by an inflation film forming method, I did.

DISCLOSURE OF THE INVENTION It is therefore an object of the present invention to provide a biodegradable film which is excellent in flexibility, resistance to heat and transparency, excellent in biomass, and particularly exhibits good effects in an inflation film forming method in view of the background of the prior art do.

In order to solve the above problems, the biodegradable film of the present invention has the following constitution. In other words,

Is a biodegradable film containing a lactic acid resin (A) and a biodegradable resin (B) other than the lactic acid resin (A) (hereinafter simply referred to as "biodegradable resin (B)") A dispersed phase containing the lactic acid resin (A) is dispersed in a long oval phase in the longitudinal direction of the film or in a long layer in the longitudinal direction of the film in a continuous phase containing the biodegradable resin (B) It has a structure, in the total 100 mass% of the lactic acid resin (a) and a biodegradable resin (B), the content of the lactic acid resin (a) content of the (% by mass) P _a, the biodegradable resin (B) of (Mass%) is P _B , the thickness (nm) of the dispersed phase is W _A , and the thickness (nm) of the continuous phase is W _B.

W _A / W _B &_amp;le; 2.0 x P _A / P _B

In the biodegradable film of the present invention, it is preferable that the thickness W _A of the dispersed phase is 5 to 100 nm.

The biodegradable film of the present invention preferably has a tear strength of 5 N / mm or more in the longitudinal direction and in the width direction by the thermal method which is the Trouser method defined in JIS K7128-1 (1998).

The biodegradable film of the present invention preferably has a ratio of P _A : P _B = 5: 95 to 60:40.

The biodegradable films of the present invention 200 ℃ temperature, shear rate of 100sec ^-1 biodegradable resin (B) in the melt viscosity of the lactic acid resin (A) in the η _A, 200 ℃ temperature, shear rate of 100sec ^-1 And the melt viscosity of the polymer is? _B , the following formula is preferably satisfied.

0.3?? _A /? _B ?

The biodegradable film of the present invention preferably contains a compatibilizing agent.

The biodegradable film of the present invention is characterized in that the lactic acid resin (A) is at least one selected from the group consisting of a block copolymer having a polyether segment and a polylactic acid segment and a block copolymer having a polyester segment and a polylactic acid segment It is preferable to include homopolylactic acid.

In the biodegradable film of the present invention, the biodegradable resin (B) is preferably at least one selected from the group consisting of polybutylene succinate, polybutylene succinate adipate, and polybutylene adipate / terephthalate .

INDUSTRIAL APPLICABILITY According to the present invention, a biodegradable film excellent in flexibility, resistance to heat and transparency, excellent in biomass property, and particularly exhibiting a favorable effect in the inflation film-forming method is provided. The biodegradable film of the present invention is useful for agriculture and forestry applications such as agricultural multi-film, pine mushroom fumigation sheet and compost pouch, which are required to have flexibility, endurance and transparency in addition to biodegradability and biomassability, A medical bag, a medical bag, a shopping bag, a garbage bag, or a bag for various industrial products.

1 is an example of a cross-sectional photograph (magnification: 50,000 times) of the biodegradable film of the present invention.

DISCLOSURE OF THE INVENTION The present invention has been extensively studied on biodegradable films excellent in flexibility, endurance and transparency, excellent in biomass property, and especially exhibiting good effects in an inflation film forming method. As a result, it has been found that a lactic acid resin, And the biodegradable resin other than the resin, and the relationship between the content ratio of these resins and the dispersed state is included in a predetermined condition. That is, the present invention relates to a biodegradable film containing a lactic acid resin (A) and a biodegradable resin (B), which comprises a continuous phase containing a biodegradable resin (B) (A) and the biodegradable resin (B) are dispersed in a long oval phase in the longitudinal direction of the film or in a long layer in the longitudinal direction of the film, and the total amount of the lactic acid resin (A) (Mass%) of the lactic acid resin (A) is P _A , the content (mass%) of the biodegradable resin (B) is P _B , the thickness (nm) of the dispersed phase is W _A , Is a biodegradable film satisfying the following formula when the thickness (nm) of the image is W _B.

W _A / W _B &_amp;le; 2.0 x P _A / P _B

Hereinafter, the biodegradable film of the present invention will be described.

(Lactic acid resin (A))

It is important that the biodegradable film of the present invention contains a lactic acid resin (A). The lactic acid resin (A) referred to in the present invention means that the constituent component containing the lactic acid unit is 5 to 100% by mass based on 100% by mass of the entire polymer. Wherein the component comprising the lactic acid unit is a biomass (plant-derived raw material).

The lactic acid resin (A) used in the present invention is a mixture of a polylactic acid resin having a constituent component containing a lactic acid unit in an amount of 60% by mass or more and 100% by mass or less and a polylactic acid resin containing a lactic acid unit in an amount of 5% (Hereinafter referred to simply as " another lactic acid resin ") of a lactic acid resin (a polymer having a lactic acid unit-containing constituent component in a lactic acid resin (A) of 5 mass% or more and less than 60 mass%). The film of the present invention is not particularly limited as long as it contains a lactic acid resin (A) and may be any of polylactic acid resin and other lactic acid resin. As described later, the film of the present invention is a lactic acid resin It is preferable that the resin (A) contains both a polylactic acid resin and another lactic acid resin.

Hereinafter, the polylactic acid resin having a constituent component containing a lactic acid unit in an amount of 60% by mass or more and 100% by mass or less will be described.

The term poly L-lactic acid in the present invention means that the content ratio of L-lactic acid unit in 100 mol% of all lactic acid units in the lactic acid resin (A) is more than 50 mol% and not more than 100 mol%. On the other hand, the poly D-lactic acid in the present invention means that the content ratio of D-lactic acid unit in 100 mol% of all lactic acid units in the lactic acid resin (A) is more than 50 mol% and not more than 100 mol%.

In the poly-L-lactic acid, the crystallinity of the resin itself changes depending on the content of the D-lactic acid unit. That is, when the content ratio of the D-lactic acid unit in the poly L-lactic acid is increased, the crystallinity of the poly L-lactic acid is lowered to approach the amorphous state. On the contrary, if the content ratio of the D- - The crystallinity of lactic acid increases. Similarly, the crystallinity of the resin itself varies depending on the content of the L-lactic acid unit in the poly-D-lactic acid. That is, when the content ratio of the L-lactic acid unit in the poly-D-lactic acid is increased, the crystallinity of the poly-D-lactic acid becomes lower and approaches the amorphous state. On the contrary, if the content of the L- - The crystallinity of lactic acid is high.

The content ratio of the L-lactic acid unit in the poly-L-lactic acid used in the present invention or the content ratio of the D-lactic acid unit in the poly-D-lactic acid used in the present invention, Is preferably 80 to 100 mol%, and more preferably 85 to 100 mol%, based on 100 mol%

The crystalline polylactic acid resin referred to in the present invention refers to a crystalline polylactic acid resin in which when the polylactic acid resin is sufficiently crystallized under heating and then measured by a differential scanning calorimeter (DSC) in an appropriate temperature range, Refers to a polylactic acid resin to be observed.

On the other hand, the amorphous polylactic acid resin referred to in the present invention refers to a polylactic acid resin that does not exhibit a definite melting point when measured similarly.

When the main component of the lactic acid resin (A) used in the present invention is poly-L-lactic acid, poly D-lactic acid is used. When the main component of the lactic acid resin (A) is poly D- In a small amount. This is because a stereo complex crystal formed by poly-L-lactic acid and poly-D-lactic acid has a higher melting point than ordinary crystals and has improved heat resistance. Here, the mass average molecular weight Mw of the polylactic acid to be mixed in a small amount is preferably smaller than the mass average molecular weight Mw of the polylactic acid as the main component from the viewpoint that the mechanical strength of the film can be maintained, and the stereo complex crystal can be efficiently formed . The mass average molecular weight Mw of the polylactic acid mixed in a small amount is preferably 0.5 to 50%, more preferably 1 to 40%, and even more preferably 2 to 30% of the mass average molecular weight Mw of the polylactic acid as the main component.

Further, the lactic acid resin (A) used in the present invention is preferably a polylactic acid block copolymer composed of a segment containing an L-lactic acid unit and a segment containing a D-lactic acid unit, from the viewpoint of improving heat resistance. In this case, since the polylactic acid block copolymer forms a stereo complex crystal in the molecule, the melting point of the polylactic acid block copolymer is higher than that of ordinary crystals. In order to form an efficient stereo complex crystal, it is preferable that the segment length satisfies Mw _Y < Mw _X / 2 with respect to the mass average molecular weight Mw _X of the polylactic acid block copolymer and the maximum mass average molecular weight Mw _Y of one segment.

The polylactic acid resin used in the present invention may be any of polylactic acid resins obtained by copolymerizing homopolylactic acid consisting solely of a lactic acid unit and monomer units other than lactic acid. Other monomers include ethylene glycol, propylene glycol, butanediol, heptanediol, hexanediol, octanediol, nonanediol, decanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, glycerin, pentaerythritol, bisphenol A, polyethylene glycol , Glycol compounds such as polypropylene glycol and polytetramethylene glycol, organic acids such as oxalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, malonic acid, glutaric acid, cyclohexanedicarboxylic acid, terephthalic acid, , Phthalic acid, naphthalene dicarboxylic acid, bis (p-carboxyphenyl) methane, anthracene dicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, 5-sodium sulfoisophthalic acid, Hydroxycarboxylic acids such as hydroxycarboxylic acid, hydroxycarboxylic acid and hydroxycarboxylic acid, hydroxycarboxylic acids such as hydroxycarboxylic acid, hydroxycarboxylic acid and hydroxycarboxylic acid, Pro lactone, valerolactone, it may be mentioned lactones, such as propiolactone, undecalactone, 1,5-octanoic sepan-2-one. The copolymerization amount of the above other monomer units is preferably 0 to 30 mol%, more preferably 0 to 10 mol%, based on 100 mol% of all the monomer units in the polymer of the polylactic acid resin. Among the above-mentioned monomer units, it is preferable to select a component having biodegradability depending on the application.

The mass average molecular weight Mw of the polylactic acid resin used in the present invention is preferably from 50,000 to 500,000, more preferably from 80,000 to 400,000, and more preferably from 100,000 to 300,000, in order to satisfy practical mechanical properties desirable.

Next, another lactic acid resin having a constituent component containing a lactic acid unit in an amount of 5 mass% or more and less than 60 mass% will be described.

It is preferable that the biodegradable film of the present invention uses a polylactic acid resin and another lactic acid resin simultaneously as the lactic acid resin (A) in order to exhibit flexibility, resistance to heat and transparency. Here, homopolylactic acid is more preferably used as the polylactic acid resin. It is particularly preferable that the other lactic acid resin is a block copolymer having a polyether segment and a polylactic acid segment and / or a block copolymer having a polyester segment and a polylactic acid segment (these block copolymers are referred to as &quot; Block copolymer plasticizer &quot;). Here, the plasticizing component is a polyether-based segment or a polyester-based segment. That is, the lactic acid resin (A) is more preferably a homopolylactic acid and a block copolymer plasticizer. Hereinafter, the &quot; block copolymer plasticizer &quot;

The block copolymer plasticizer exhibits flexibility by plasticizing the polylactic acid resin and functions as a compatibilizing agent for the polylactic acid resin and the biodegradable resin (B), and a dispersion structure (to be described later) by adjusting the melt viscosity of the polylactic acid resin Thereby exhibiting resistance to heat and transparency.

The mass ratio of the polylactic acid segment in the block copolymer plasticizer is preferably 50% by mass or less based on the total mass of the block copolymer plasticizer because a smaller amount of the polylactic acid segment can give the desired flexibility, and the mass ratio of 5% . The number average molecular weight Mn of the polylactic acid segment in one molecule of the block copolymer plasticizer is preferably 1,200 to 10,000. When the number average molecular weight Mn of the polylactic acid segment in the block copolymer plasticizer is 1,200 or more, sufficient affinity is generated between the block copolymer plasticizer and the polylactic acid resin, and a part of the segment is contained in the crystal formed of the polylactic acid resin So that a so-called eutectic is formed, so that an action of connecting and fixing the block copolymer plasticizer to the polylactic acid resin is produced, thereby exhibiting a great effect in suppressing the bleeding out of the block copolymer plasticizer. The number average molecular weight Mn of the polylactic acid segment in the block copolymer plasticizer is more preferably 1,500 to 6,000, and still more preferably 2,000 to 5,000. The polylactic acid segment in the block copolymer plasticizer is preferably 95 to 100% by mass of L-lactic acid or 95 to 100% by mass of D-lactic acid because the bleeding out is particularly suppressed.

The block copolymer plasticizer has at least one selected from the group consisting of a polyether segment and a polyester segment, but a block copolymer of a polyether segment and a polylactic acid segment is preferred to have a desired flexibility It is preferable from the viewpoint that it can be given. In the block copolymer of the polyether segment and the polylactic acid segment, the polyether segment is more preferably a segment containing a polyalkylene ether from the viewpoint of giving a desired flexibility by adding a smaller amount . Specific examples of the polyether-based segment include segments containing polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyethylene glycol-polypropylene glycol copolymer, etc. Particularly, the segments containing polyethylene glycol are polylactic acid- Since the affinity with the resin is high, the reforming efficiency is excellent. Particularly, the addition of a small amount is preferable because the desired flexibility can be imparted.

In addition, when the block copolymer plasticizer has a segment containing a polyalkylene ether, the polyalkylene ether segment tends to be easily oxidized and thermally decomposed when heated at the time of molding or the like. Therefore, the hindered phenol- , A hindered amine-based antioxidant or a thermal stabilizer such as phosphorus is preferably used in combination.

In the case where the block copolymer plasticizer has a polyester segment, it is preferable that the poly (glycolic acid), poly (3-hydroxybutyrate), poly (3-hydroxybutyrate. 3-hydroxyvalerate), polycaprolactone, , Propanediol, and butanediol, and polyesters containing an aliphatic dicarboxylic acid such as succinic acid, sebacic acid, and adipic acid are preferably used as polyester segments.

In addition, the block copolymer plasticizer may contain either of the components of the polyether-based segment and the polyester-based segment in one molecule thereof, or may be either one of the components. From the viewpoint of the productivity and cost of the plasticizer, it is preferable to use a polyether-based segment from the viewpoint of imparting desired flexibility by adding a smaller amount of a plasticizer when the plasticizer is one of the components. A preferred embodiment of the block copolymer plasticizer is a block copolymer of a polyether segment and a polylactic acid segment.

The number average molecular weight Mn of the polyether segment or the polyester segment in one molecule of the block copolymer plasticizer is preferably 7,000 to 20,000. When the composition is in the above-described range, when the composition constituting the biodegradable film of the present invention is made sufficiently flexible and a composition containing the lactic acid resin (A) and the biodegradable resin (B) is used, , The inflation film forming method and the like can be stabilized.

There is no particular limitation on the order constitution of each of the segment blocks of the polylactic acid segment and at least one selected from the group consisting of the polyether segment and the polyester segment, but from the viewpoint of suppressing the bleeding out more effectively, It is preferred that the polylactic acid segment is at the end of the block copolymer plasticizer molecule.

Next, the case where polyethylene glycol (hereinafter referred to as PEG) having a hydroxyl group terminal at both ends is employed as the polyether-based segment will be described in detail.

The number average molecular weight (hereinafter referred to as PEG number average molecular weight, Mn _PEG ) of _PEG having hydroxyl ends at both terminals is calculated from the hydroxyl value obtained by a neutralization method or the like in the case of commercially available products. In the system was added portion-lactide w _L by mass relative to the PEG in w _E parts by weight having a hydroxyl group terminal at both ends, if enough reaction to ring-opening addition polymerization of a lactide in the amount of hydroxyl end of the PEG, substantially PLA-PEG-PLA (Wherein PLA represents polylactic acid). &Lt; tb &gt;&lt; TABLE &gt; This reaction is carried out optionally in the presence of a catalyst such as tin octylate. The number average molecular weight Mn of one polylactic acid segment of the block copolymer plasticizer can be obtained by (1/2) x (w _L / w _E ) x Mn _PEG . Further, the mass ratio of the polylactic acid segment component to the entire block copolymer plasticizer can be determined by 100 x w _L / (w _L + w _E ). Further, the mass ratio of the plasticizer component excluding the polylactic acid segment component to the whole block copolymer plasticizer can be determined by 100 x w _E / (w _L + w _E ).

As a method for separating the block copolymer plasticizer from the biodegradable film of the present invention in order to evaluate the number average molecular weight Mn of the polyether segment, the polyester segment and the polylactic acid segment in the block copolymer plasticizer, For example, the biodegradable film is uniformly dissolved in a suitable and suitable solvent such as chloroform, and then the solution is added dropwise to a suitable poor solvent such as water or a mixed solution of water and methanol. The polylactic acid resin and the biodegradable resin (B) And a reprecipitation method in which the precipitate contained is removed and the solvent of the filtrate is volatilized to obtain a block copolymer plasticizer. The number average molecular weight Mn of the thus-obtained block copolymer plasticizer was measured by gel permeation chromatography (GPC), and it was found by ¹ H-NMR measurement that the polylactic acid segment, the polyether segment and / Based segment. The molecular weight of one polylactic acid segment of the block copolymer is expressed by the following formula: Mn 占 {1 / (number of polylactic acid segments)} (I _PLA 72) / {(I _PE UM _PE / N _PE ) + I _PLA x 72)}. However, I _PLA is in the signal integrated intensity in ¹ H-NMR measurement that is derived from hydrogen, I _PE is a polyether-based segment and / or ^poly-1 H-NMR measurement that is derived from a polyester-based segment of the methine group PLA backbone portion UM _PE is the molecular weight of the monomer unit of the polyether-based segment and / or the polyester-based segment, N _PE is the chemically equivalent weight of the polyether-based segment and / or the polyester- The number of protons. The number average molecular weight of the polyether segment and / or the polyester segment can be calculated by Mn- (number average molecular weight of polylactic acid segment) x (number of polylactic acid segments). Here, Mn represents the number average molecular weight of the block copolymer plasticizer measured by GPC.

The block copolymer plasticizer contained in the composition constituting the biodegradable film of the present invention is preferably 1 to 30% by mass in 100% by mass of the lactic acid resin (A). When the content is 1% by mass or more, the functions as the above-mentioned plasticizer, compatibilizer and melt viscosity adjuster can be sufficiently exhibited. When the content is 30% by mass or less, the elasticity of the film becomes strong, and handling, strength, durability, The bleeding-out property of the ink is increased. The content of the block copolymer plasticizer is preferably 5 to 25% by mass, more preferably 10 to 20% by mass, based on 100% by mass of the lactic acid resin (A).

The content of the block copolymer plasticizer in the total 100 mass% of the lactic acid resin (A) is preferably 1 to 30 mass%, and the remaining 70 to 99 mass% is preferably the polylactic acid resin.

As a method for producing the lactic acid resin (A), a known polymerization method can be used, as will be described later in detail. Examples thereof include a direct polymerization method using lactic acid and a ring-opening polymerization method using lactide.

The biodegradable film of the present invention preferably contains 5 to 60 mass% of the lactic acid resin (A) in 100 mass% of the total composition constituting the biodegradable film. When the lactic acid resin (A) is contained in an amount of not less than 5% by mass, the transparency and the biomass property are excellent, and the lactic acid resin (A) is contained in an amount of not more than 60% by mass in 100% by mass of the composition constituting the biodegradable film , Flexibility and endurance. The content of the lactic acid resin (A) is more preferably 20 to 55 mass%, and still more preferably 35 to 50 mass%, in 100 mass% of the total composition constituting the biodegradable film.

(Biodegradable resin (B))

It is important for the biodegradable film of the present invention to contain a biodegradable resin (B) other than the lactic acid resin (A) in order to exhibit flexibility and endurance. The biodegradable resin (B) also serves to adjust the biodegradation rate and to adjust the melt viscosity of the whole composition constituting the biodegradable film to form a stable bubble, particularly in the inflation film formation method.

Specific examples of the biodegradable resin (B) include polyglycolic acid, poly (3-hydroxybutyrate), poly (3-hydroxybutyrate · 3-hydroxyvalerate), polycaprolactone, polyethylene succinate, Aliphatic polyesters such as polybutylene succinate, polybutylene succinate and adipate, polyethylene succinate-terephthalate, polybutylene succinate-terephthalate, polybutylene adipate-terephthalate, and the like A resin containing an aliphatic aromatic polyester, a thermoplastic starch, a starch and an aliphatic (aromatic) polyester, and a cellulose ester are preferably used. Further, from the viewpoint of enhancing the biomass property, these resins are preferably used a plant-derived raw material in part or all of the constituent components.

Among them, the biodegradable resin (B) is preferably selected from the group consisting of polybutylene succinate, polybutylene succinate adipate and polybutylene adipate / terephthalate from the viewpoint of the effect of improving flexibility and endurance Is more preferably used. Polybutylene adipate / terephthalate is the most effective in improving the flexibility and endurance.

The biodegradable resin (B) contained in the biodegradable film of the present invention is preferably 40 to 95% by mass of 100% by mass of the total composition constituting the biodegradable film. When it is 40 mass% or more, the effect of improving flexibility and endurance is easily obtained, and when it is 95 mass% or less, transparency and appropriate biodegradability can be imparted. The biodegradable resin (B) is more preferably 45 to 80% by mass, and more preferably 50 to 65% by mass in 100% by mass of the total composition constituting the biodegradable film.

(Plasticizer)

The biodegradable film of the present invention may contain a plasticizer in a range that does not disturb the biodegradability in order to impart flexibility mainly.

Examples of the plasticizer include phthalate esters such as diethyl phthalate, dioctyl phthalate and dicyclohexyl phthalate, di-1-butyl adipate, di-n-octyl adipate, di- 2-ethylhexyl, and other aliphatic dibasic acid esters, diphenyl-2-ethylhexyl phosphate and diphenyloctyl phosphate, tributyl acetylcitrate, tri-2-ethylhexyl acetylcitrate, tributyl , Polyhydric alcohol esters such as glycerin triacetate and triethylene glycol dicaprylate, epoxidized soybean oil, epoxidized flaxseed oil such as epoxidized flaxseed oil, Epoxy-based plasticizers such as maleic fatty acid butyl ester and octyl stearate epoxy, plasticizers such as polypropylene glycol sebacic acid ester, There may be mentioned polyalkylene ether type, ether ester type, such as recall, acrylate-based and the like. Of these, it is also possible to use a mixture of plural kinds or more as a plasticizer.

From the viewpoints of the anti-bleeding out property of the plasticizer and the blocking resistance of the film, for example, a polyethylene glycol having a number average molecular weight Mn of 1,000 or more and a solid phase at room temperature (20 캜 15 캜) desirable.

(A mixture of a crystalline polylactic acid resin and an amorphous polylactic acid resin)

The polylactic acid resin which is one of the lactic acid resin (A) contained in the composition constituting the biodegradable film of the present invention may be a mixture of a crystalline polylactic acid resin and an amorphous polylactic acid resin. By making the mixture, the crystallinity, the amorphous property, and the advantages of the respective polylactic acid resins can be achieved at the same time.

Further, as described above, the crystalline polylactic acid resin means a resin obtained by sufficiently crystallizing the polylactic acid resin under heating, and then, when measurement is carried out by a differential scanning calorimeter (DSC) in a suitable temperature range, the melting point derived from the polylactic acid component Refers to the observed polylactic acid resin.

On the other hand, the amorphous polylactic acid resin refers to a polylactic acid resin which does not show a definite melting point when the same measurement is carried out.

That is, the content of the crystalline polylactic acid resin is preferable for improving the film's resistance to heat, heat resistance, and blocking resistance. When the above-mentioned block copolymer plasticizer is used, the crystalline polylactic acid resin exhibits a great effect on anti-bleeding out property by forming a step with the polylactic acid segment possessed by the block copolymer plasticizer.

On the other hand, the incorporation of the amorphous polylactic acid resin is preferable for improving the flexibility and bleeding-out property of the film. This has been influenced by the fact that the plasticizer provides an amorphous portion which can be dispersed.

The crystalline polylactic acid resin used in the biodegradable film of the present invention is preferably a crystalline polylactic acid resin having a content ratio of L-lactic acid unit in the poly L-lactic acid or a content of L in the poly D-lactic acid, - the content of the lactic acid unit is preferably 94 to 100 mol%, more preferably 96 to 100 mol%, and still more preferably 98 to 100 mol% in 100 mol% of the total lactic acid unit.

When the amount of the polylactic acid resin in the composition constituting the biodegradable film of the present invention is 100 mass%, the proportion of the crystalline polylactic acid resin is preferably 5 to 80 mass%, more preferably 10 to 60 mass% , And still more preferably from 20 to 40 mass%.

(Compatibilizer)

In the biodegradable film of the present invention, it is preferable to include a compatibilizing agent of the polylactic acid resin and the biodegradable resin (B) for the purpose of improving the thermostability and transparency.

The type of the compatibilizing agent is not particularly limited, but mainly classified into the following three types. First, at least one structure selected from the structure of the polylactic acid resin itself, the structure similar to the polylactic acid resin, the structure compatible with the polylactic acid resin, the structure itself of the biodegradable resin (B) Has a structure having a structure similar to that of the biodegradable resin (B), and a structure having at least one structure selected from structures having good compatibility with the biodegradable resin (B). The second one has a functional group capable of chemically bonding to either the lactic acid resin (A) or the biodegradable resin (B) or both terminal groups (carboxyl group or hydroxyl group) by an addition reaction or a condensation reaction. The third one is to have a catalytic ability of a condensation reaction between the lactic acid resin (A) and the biodegradable resin (B) or an ester exchange reaction.

As specific examples of the first classification, polylactic acid is excellent in compatibility with an acrylic resin, and therefore, for example, a copolymer of a polyolefin and an acrylic resin, and a copolymer of a polyester and an acrylic resin can be given.

Specific examples of the second group include compounds containing at least one functional group selected from a glycidyl group, an acid anhydride group, a carbodiimide group, an isocyanate group, an oxazoline group and an amino group as a functional group.

Examples of the compound containing a glycidyl group include a glycidyl ether compound, a glycidyl ester compound, a glycidyl amine compound, a glycidyl imide compound, a glycidyl (meth) acrylate compound, and an alicyclic epoxy compound . Commercially available products include "BIOMAX" (registered trademark) Strong series of ethylene, a copolymer of acrylic ester and glycidyl (meth) acrylate, DuPont, "LOTADER" (registered trademark) series of Arkema , "JONCRYL" (registered trademark) series of BASF which is an acryl / styrene copolymer containing glycidyl groups, "LEGEDA" (registered trademark) series of TOA KOSEI CO., Which is an acrylic resin containing glycidyl groups, And " ALPHON " (registered trademark) series.

Examples of the compound containing an acid anhydride group include compounds containing succinic anhydride, maleic anhydride, phthalic anhydride and the like. Commercial "BONDINE" series of ethylene and acrylic ester, copolymer of maleic anhydride "OREVAC" (trade mark) series of maleic anhydride graft polymer, "BONDINE" series of ARKEMASA, Quot; KRATON ", which is obtained by copolymerizing maleic anhydride with styrene-ethylene-butylene-styrene copolymer (SEBS), " Bynel " series manufactured by Sanyo Chemical Industries, (Registered trademark) series, and the like.

The compound containing a carbodiimide group is a compound having a carbodiimide group represented by at least one (-N = C = N-) in the molecule, and commercially available ones include "Carbodi (Registered trademark) series of Rhein Chemie, and "STABAXOL" (registered trademark) series of Rhein Chemie.

Examples of the compound containing an isocyanate group include hexamethylene diisocyanate and the like.

Specific examples of the third class include organic metal compounds and sulfuric acid compounds. Examples of the organic metal compound include carboxylic acid metal salt compounds such as zinc stearate, zinc acetate, magnesium acetate and manganese acetate, organic titanium compounds such as titanium tetraisopropoxide, and organoaluminum compounds. Examples of the sulfuric acid compound include p-toluenesulfonic acid, dodecylbenzenesulfonic acid, sodium p-toluenesulfonate, and sodium dodecylbenzenesulfonate.

The blending amount of the compatibilizing agent in the biodegradable film of the present invention is 0.01 to 30 mass parts per 100 mass parts in total of the lactic acid resin (A) and the biodegradable resin (B) More preferably 0.05 to 20 parts by mass, still more preferably 0.1 to 10 parts by mass, particularly preferably 0.5 to 3 parts by mass. When the blending amount of the compatibilizing agent is 0.01 parts by mass or more, the effect of improving the transparency and the thermochromism is sufficiently exhibited. When the amount is 30 parts by mass or less, the fluidity can be prevented from deteriorating due to gelation or the like. The third classification is 0.01 to 3 parts by mass, more preferably 0.05 to 2 parts by mass, and most preferably 0.1 to 3 parts by mass based on 100 parts by mass of the total amount of the lactic acid resin (A) and the biodegradable resin (B) To 1 part by mass is more preferable. When the blending amount of the compatibilizing agent is 0.01 parts by mass or more, the effect of improving the transparency and the thermochromism is sufficiently exhibited, and when it is 3 parts by mass or less, the decrease of the melt viscosity can be suppressed.

(Distributed structure)

The biodegradable film of the present invention is characterized in that a dispersed phase containing a lactic acid resin (A) is dispersed in a continuous phase containing a biodegradable resin (B) other than the lactic acid resin in the cross section in the longitudinal direction and the thickness direction of the film, (A) in a total amount of 100% by mass of the lactic acid resin (A) and the biodegradable resin (B), wherein the lactic acid resin is dispersed in a long oval phase in the longitudinal direction of the film or in a long layer in the longitudinal direction of the film. when the content (mass%) of P _a, the biodegradable resin (B) content (mass%) of P _B, the thickness (nm) thickness (nm) W _a, the continuous phase of the dispersion phase of a W _B, It is important to satisfy the following equation.

W _A / W _B &_amp;le; 2.0 x P _A / P _B

Here, the continuous phase and the dispersed phase means a solution of a so-called sea-island structure in a continuous phase and a dispersed phase.

In the case of the biodegradable film of the present invention, since the dispersed phase is long in the longitudinal direction of the film, it may be difficult to judge whether it is a continuous phase or a dispersed phase. In this case, when confirming the dispersion structure in a transmission electron microscope (TEM) to be described later, it is judged that the observation range in the longitudinal direction of the film is not overlapped, and the one in which the tip of the structure exists is a dispersed phase.

The inventors have found that the lactic acid resin (A) and the biodegradable resin (B) constituting the biodegradable film have a dispersion structure as described above, thereby imparting flexibility, endurance, transparency and biomassability to the biodegradable film . Namely, the polylactic acid resin is a resin which is compatible with biomass and biodegradability. Since the thermoresponsiveness of the biodegradable resin is low, it is possible to solve the problem by adjusting the following three factors (i) to (iii) Respectively.

(i) Since the lactic acid resin (A) is a dispersed phase and the biodegradable resin (B) is a continuous phase, flexibility and endurance of the film can be improved. The method for achieving such a phase structure is as follows: (a) the ratio of P _A to P _B is set within a preferable range described below; (b) the melt viscosity of the lactic acid resin (A) and the biodegradable resin It may be set to a preferable range described later.

Here, the dispersed phase of the lactic acid resin (A) means that the lactic acid resin (A) is the largest component in all components in the dispersed phase. Therefore, the dispersed phase containing the lactic acid resin (A) may contain components other than the lactic acid resin (A) such as various additives, organic lubricants, particles, and other components other than the lactic acid resin (A) have.

Likewise, the continuous phase of the biodegradable resin (B) means that the biodegradable resin (B) is the largest component in terms of mass in all the components in the continuous phase. Therefore, a component other than the biodegradable resin (B) may be contained in the dispersed phase containing the biodegradable resin (B).

(ii) a structure in which the dispersed phase containing the lactic acid resin (A) is dispersed in a long oval phase in the longitudinal direction of the film or in a long layer in the longitudinal direction of the film in a cross section in the longitudinal direction and the thickness direction of the film, It is possible to reduce the influence of the film of the lactic acid resin (A) on the thermostability of the film, and as a result, it is possible to improve the thermostability of the film and further improve the transparency. Here, the terms &quot; oval phase &quot; and &quot; layer phase &quot; means a case in which both ends in the longitudinal direction are observed when observed at a magnification in which the entire thickness direction of the film is observed at the time of observation under a transmission electron microscope , And a case where at least one end in the longitudinal direction is not observed is referred to as &quot; layered &quot;. The method for achieving such a dispersed structure includes the method (b) described above, and (c) the blowing ratio and the draw ratio when the film is formed by inflation into a preferable range described later.

(iii) By satisfying W _A / W _B ≤ 2.0 × P _A / P _B , the influence of the film of the lactic acid resin (A) on the thermostability of the film can be reduced, and as a result, Do. This condition indicates that the ratio (WA / WB) of the dispersed phase to the thickness of the continuous phase in a film produced at a specific compounding ratio (PA / PB) is not more than a predetermined value. ) Or the method (c) above. This condition _{W A / W B ≤1.5P A /} P B is preferably, W _A / W _B more preferably ≤1.2P _A / P _B.

The biodegradable film of the present invention preferably has a thickness W _A of 5 to 100 nm in order to exhibit high transparency and high thermostability. More preferably from 10 to 60 nm, still more preferably from 20 to 50 nm, particularly preferably from 20 to 40 nm. For the same purpose, it is preferable that the thickness W _B of the dispersed phase is 10 to 100 nm. More preferably from 30 to 80 nm, still more preferably from 30 to 70 nm, particularly preferably from 30 to 60 nm. The method (b) or the method (c) can be used to adjust the thickness W _A of the dispersed phase to 5 to 100 nm.

This results in that the lactic acid resin (A) and the biodegradable resin (B) both exhibit endurance of the film as a whole by precisely dispersing the lactic acid resin (A) Is made smaller than the wavelength of the visible light, thereby exhibiting transparency.

(The content P _A of the lactic acid resin (A) and the content P _B of the biodegradable resin ( _B )

The biodegradable film of the present invention preferably has a dispersed structure as described above and has P _A : P _B = 5: 95 to 60:40 in order to exhibit high biomass property in addition to high flexibility, transparency and endurance . More preferably, P _A : P _B = 20:80 to 55:45, and more preferably P _A : P _B = 35:65 to 50:50. Here, the units of P _A and P _B are mass%.

(The relationship between the melt viscosity of the lactic acid resin (A) and the biodegradable resin (B)

In the biodegradable film of the present invention, the melt viscosity of the lactic acid resin (A) at a temperature of 200 캜 and a shear rate of 100 sec ^-1 is η _A , a temperature is 200 캜, a shear rate is 100 sec when the melt viscosity of the biodegradable resin (B) in the ^-1 to η _B, it is preferable to satisfy the 0.3≤η _a / η _B ≤1.1. More preferably 0.5?? _A /? _B ? 0.9 and still more preferably 0.5?? _A /? _B ? 0.6.

Here, the melt viscosity? _A of the lactic acid resin (A) is measured as a resin obtained by melt-kneading the lactic acid resin (A) when the lactic acid resin (A) contains a polylactic acid resin and another lactic acid resin.

The preferable range of melt viscosity? _A of the lactic acid resin (A) is 400 to 1,300 Pa · s, more preferably 400 to 1,000 Pa · s, and still more preferably 700 to 1,000 Pa · s.

The preferable range of the melt viscosity? _B of the biodegradable resin (B) is 700 to 1,300 Pa · s, more preferably 1,100 to 1,300 Pa · s, further preferably 1,100 to 1,250 Pa · s, particularly preferably 1,200 To 1,250 Pa · s.

(Tear strength)

The biodegradable film of the present invention preferably has a tear strength in both the longitudinal direction and the transverse direction of the film of 5 N / mm or more by the tracer thermal method defined in JIS K7128-1 (1998). More preferably 11 N / mm or more, further preferably 19 N / mm or more. In addition, although a larger tear strength is preferable, it is considered that the upper limit is about 200 N / mm, which is a realizable value. If the tear strength in the longitudinal direction and the width direction of the film is 5 N / mm or more, the film can be used for agriculture, such as agricultural multi-film, pine mushroom sheet, compost bag, food packaging for vegetables and fruits, , Garbage bags, and the like, or a bag of various industrial products, sufficient tear resistance is obtained, and tearing is difficult and practicality is improved.

The method (a), the method (b), and the method (c) can be mentioned as the method for making the tear strength in the longitudinal direction and the width direction of the film 5 N / mm or more.

(Shinto)

The stretchability of the biodegradable film of the present invention in both the longitudinal direction and the width direction (direction perpendicular to the longitudinal direction) is preferably 200% or more and 700% or less. When the elongation is 200% or more, the heat resistance is increased, and furthermore, it is difficult to tear when used for agricultural and forestry applications, food packaging applications, medical individual packaging, shopping bags, garbage bags, and various industrial products Practicality is improved. When the elongation is 700% or less, loosening or wrinkling at the time of traveling between rolls or winding at the time of film formation is unlikely to occur, and the winding state and releasability of the roll become good. The elongation in the longitudinal direction and the width direction is more preferably 250% or more and 600% or less, and still more preferably 300% or more and 500% or less.

As a method for setting both the elongation in the longitudinal direction and the width direction to 200 to 700%, there may be mentioned a method in which the blending amounts of the lactic acid resin (A) and the biodegradable resin (B) are respectively set within the preferable ranges described above.

(Tensile modulus)

In order to impart sufficient flexibility to the biodegradable film of the present invention, the tensile elastic modulus of each of the longitudinal direction and the width direction is preferably 100 to 1,500 MPa. The tensile modulus is more preferably 200 to 1,200 MPa, and still more preferably 300 to 1,000 MPa.

As a method for setting the tensile elastic modulus in each of the longitudinal direction and the width direction to 100 to 1,500 MPa, the blending amount of the lactic acid resin (A) and the biodegradable resin (B) may be respectively set within the above preferable range.

(thickness)

The biodegradable film of the present invention preferably has a film thickness of 5 to 200 mu m. By setting the film thickness to 5 占 퐉 or more, the elasticity in the form of a film becomes strong, handling property is excellent, and the wound state and releaseability of the roll become good. When the film thickness is 200 탆 or less, the flexibility is improved and the handling property is improved when the film is used for agricultural and forestry applications, food packaging applications, individual medical packaging, shopping bags, garbage bags, And particularly in the inflation film-forming method, the bubble is not destabilized by its own weight. The film thickness is more preferably 7 to 150 mu m, further preferably 10 to 100 mu m, and particularly preferably 12 to 50 mu m.

(Organic lubricant)

The composition constituting the biodegradable film of the present invention preferably contains 0.1 to 5% by mass of an organic lubricant in 100% by mass of the whole composition. In this case, blocking after winding can be suppressed well. In addition, problems such as deterioration of melt viscosity or workability due to excessive addition of organic lubricant, and appearance defects such as bleeding out or increase in haze in the case of film are also unlikely to occur.

The organic lubricant is not particularly limited, and various materials can be used. For example, a fatty acid amide-based organic lubricant can be used. Among them, from the viewpoint of exhibiting better blocking resistance, an organic lubricant having a relatively high melting point such as ethylenebisstearic acid amide, ethylenebisoleic acid amide, and ethylenebislauric acid amide is preferable.

(Hayes)

The biodegradable film of the present invention preferably has a haze of 50% or less, more preferably 40% or less, more preferably 30% or less, and particularly preferably 20% or less. When the haze is 50% or less, it is possible to easily confirm the contents when molded in various applications such as food packaging use, individual medical packaging, shopping bags, garbage bags, and various industrial products, And it is often desirable due to high designability such as aesthetics as a product. From the general characteristics of the lactic acid resin (A) and the biodegradable resin (B), it is difficult to make the haze of the biodegradable film less than 1%, and therefore the lower limit is about 1%.

(additive)

The composition constituting the biodegradable film of the present invention may contain additives other than those described above within a range not to impair the effect of the present invention. For example, it is possible to use a known crystal nucleating agent, an antioxidant, an ultraviolet stabilizer, a coloring inhibitor, a matting agent, a deodorant, a flame retardant, a lubricant, an antistatic agent, an antioxidant, an ion exchanger, a tackifier, a defoaming agent, An end blocker, and the like.

Examples of the crystal nucleating agent include organic compounds such as melamine compounds, phenylphosphonic acid metal salts, benzenecarbamide derivatives, aliphatic carboxylic acid hydrazides, aromatic carboxylic acid hydrazides, sorbitol compounds, amino acids, polypeptides, metal phthalocyanines Can be used. As inorganic crystal nucleating agents, silicate minerals such as talc, clay, mica, and kaolinite, and carbon black can be preferably used.

As the antioxidant, a hindered phenol-based, hindered amine-based, or the like can be preferably used.

Examples of the coloring pigments include inorganic pigments such as carbon black, titanium oxide, zinc oxide and iron oxide, as well as inorganic pigments such as cyanine, styrene, phthalocyanine, anthraquinone, perinone, isoindolinone, quinophthalone, , And an organic pigment such as a thioindigo system can be preferably used.

Examples of the terminal blocking agent include an addition reaction type compound such as a carbodiimide compound, an epoxy compound, and an oxazoline compound. End blocking of the lactic acid resin (A) or the biodegradable resin (B) is preferable from the viewpoint of suppressing the strength decrease due to hydrolysis and giving good durability by lowering the carboxyl terminal end concentration.

(particle)

Particles may be added to the composition constituting the biodegradable film of the present invention for the purpose of improving lubricity and blocking resistance of the processed product.

These particles may be inorganic particles or organic particles without any particular limitation, and examples thereof include silicon oxide such as silica, various carbonates such as calcium carbonate, magnesium carbonate and barium carbonate, various sulphates such as calcium sulfate and barium sulfate, wollastonite, potassium titanate , Various complex oxides such as aluminum boride and sepiolite, various phosphates such as lithium phosphate, calcium phosphate and magnesium phosphate, various oxides such as aluminum oxide, titanium oxide, zirconium oxide and zinc oxide, hydroxides such as aluminum hydroxide and magnesium hydroxide , Lithium fluoride, and the like can be used.

(Manufacturing method)

Next, the method for producing the biodegradable film of the present invention is specifically described, but the present invention is not limited thereto.

The polylactic acid resin in the present invention can be obtained, for example, by the following method. As the raw material, a hydroxycarboxylic acid other than the above-mentioned lactic acid component may be used in combination with the lactic acid component of L-lactic acid or D-lactic acid as a main component. In addition, cyclic ester intermediates of hydroxycarboxylic acids such as lactide, glycolide and the like may be used as raw materials. Further, 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 material, or a method of ring-opening polymerization of the cyclic ester intermediate. For example, in the case of direct dehydration condensation, lactic acids or lactic acids and hydroxycarboxylic acids are preferably azeotropically dehydrated and condensed in the presence of an organic solvent, particularly a phenyl ether solvent, particularly preferably by azeotropic distillation The solvent is removed from the solvent, and the solvent is brought into a substantially anhydrous state, and then the solvent is returned to the reaction system. Thus, a high molecular weight polymer is obtained.

It is also known that a polymer having a high molecular weight can be obtained by ring-opening polymerization under reduced pressure using a catalyst such as tin octylate, for example, a cyclic ester intermediate such as lactide. At this time, a method of adjusting the removal conditions of water and a low molecular weight compound in heating and refluxing in an organic solvent, a method of deactivating the catalyst by deactivating the catalyst after completion of the polymerization reaction, a method of heat- , A polymer having a small lactide amount can be obtained.

In order to obtain a composition constituting the biodegradable film of the present invention, that is, a composition containing a lactic acid resin (A), a biodegradable resin (B), or other components, a solution obtained by dissolving each component in a solvent is uniformly mixed It is also possible to prepare the composition by removing the solvent therefrom. However, the melt-kneading method for producing the composition by melt-kneading the respective components, which is a practical production method in which a step of dissolving the starting material and removing the solvent is not required in the solvent desirable. The melt-kneading method thereof is not particularly limited, and a commonly known mixer such as a kneader, a roll mill, a Benbury mixer, a single screw or a twin screw extruder may be used. Among them, from the viewpoint of productivity, the use of a single-screw or twin-screw extruder is preferable.

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 180 ° C to 210 ° C, in order to prevent deterioration of the lactic acid resin (A).

The biodegradable film of the present invention can be obtained by a conventional film production method such as a known inflation method, tubular method, T-die casting method, or the like using the composition obtained by the above-described method, The inflation method is preferable in order to obtain the dispersion structure of the biodegradable film.

In the production of the biodegradable film of the present invention, for example, when the composition obtained by the above-described method is temporarily pelletized and again melted and kneaded and extruded and formed, the pellet is dried at 60 to 100 ° C for 6 hours or more A polylactic acid resin having a water content of not more than 1,200 ppm, preferably not more than 500 ppm, more preferably not more than 200 ppm, is preferably used. Further, it is preferable to reduce the lactide content in the composition containing the polylactic acid resin or the like by vacuum drying under a high vacuum of 10 Torr or less. It is possible to prevent the hydrolysis during melt-kneading, thereby preventing the molecular weight from lowering, by decreasing the water content of the composition containing polylactic acid resin or the like to 1,200 ppm or less and decreasing the lactide content, , It is preferable that the melt viscosity is set at an appropriate level and the film-forming step can be stabilized. Further, from the same viewpoint, when pelletization or melt extrusion / film formation is once carried out, it is preferable to perform melt extrusion while removing volatiles such as water and low molecular weight water using a twin screw extruder equipped with a vent hole.

When the biodegradable film of the present invention is produced by the inflation method, for example, the composition prepared by the method as described above is melt-extruded by a twin-screw extruder equipped with a vent hole to be led to a annular die, (Bubbles) by supplying dry air to the inside, and uniformly air-cooled and solidified by air ring, folded flat with a nip roll, pulled at a predetermined take-off speed, One end can be incised and wound.

In the inflation film formation of the biodegradable film of the present invention, adjustment of the blow ratio and the draw ratio at inflation film formation is important. Here, the blow-by-turn is determined by the stretching ratio in the width direction of the film (the length in the width direction of the film when one end is cut and wound) / (the length of the circumference of the annular die). (Drawing speed) / (Discharge speed from annular die) at draw draw ratio in the longitudinal direction of the film. In practical use, the film thickness after film formation (blown film thickness) Ratio)}. In the biodegradable film of the present invention, in order to form the above-described dispersion structure, the blow ratio is preferably 1.6 to 4.0, and the draw ratio is preferably 10 to 50. The blow ratio is more preferably 2.2 to 3.4, and still more preferably 2.8 to 3.4. The draw ratio is more preferably from 15 to 45, and still more preferably from 20 to 35. [

The lip gap of the annular die can be adjusted to a desired film thickness upon film formation with the above-mentioned preferable blow ratio and draw ratio, and is usually 0.6 to 1.8, preferably 1.2 to 1.6. Further, it is preferable to use a helical die in view of the thickness precision and uniformity of the annular die, and it is preferable to use a rotary die of the annular die from the same viewpoint.

The extrusion temperature for inflation film formation of the biodegradable film of the present invention is usually in the range of 150 to 240 캜, preferably 180 to 210 캜, the temperature of the annular die is usually in the range of 150 to 190 캜, 170 deg. C is preferable.

After molding into a film, heat treatment may be performed in a heating roll or an oven in order to suppress heat shrinkage of the film. In addition, various surface treatments may be performed for the purpose of improving printability, laminating suitability, coating suitability, and the like. Examples of the surface treatment method include a corona discharge treatment, a plasma treatment, a flame treatment, and an acid treatment, and any of these methods can be used. However, since continuous treatment is possible, The corona discharge treatment can be exemplified as the most preferable one.

<Examples>

Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited thereto at all.

[Measurement and evaluation method]

Measurement and evaluation shown in the examples were carried out under the following conditions.

(1) Distributed structure

The film was dyed with ruthenic acid, embedded in an epoxy resin, and then cut in a direction perpendicular to the film surface parallel to the longitudinal direction of the film using an ultra-microtome to prepare an ultra-sliced piece. The cut surface was first observed under a condition of an acceleration voltage of 100 kV by using a transmission electron microscope (H-7100 type, manufactured by Hitachi High Technology Co., Ltd.) at a magnification in which the entire thickness direction of the film was visible, Photographs were taken at a magnification of 50,000 times with respect to the central portion in the thickness direction with respect to each of the three regions when the images were divided into three equal intervals.

The photographed pictures are cut vertically in the longitudinal direction of the film into a square of 15 cm x 15 cm and a line crossing the central portion of the longitudinal length is drawn (i.e., a line dividing the square into upper and lower areas is drawn). The phase structure at the left and right ends is omitted and the remaining all of the dispersed phase and the thickness of the continuous phase are set at a point of intersection between the line and a boundary portion of a long stratum in the longitudinal direction of the film or a long layer- 0.1 mm. Similarly, the thicknesses of the dispersed phase and the continuous phase were measured for the remaining two regions, and the total average value was calculated for each of the dispersed phase and the continuous phase, and W _A , W _B (nm) Rounded).

In addition, when it is difficult to judge whether the continuous phase or the dispersed phase is a continuous phase or a dispersed phase because the dispersed phase is long in the longitudinal direction of the film, in confirming the dispersed structure in the transmission electron microscope (TEM) , It is judged that the end where the tip of the structure is present is the dispersed phase.

Fig. 1 shows an example of a cross-sectional photograph (magnification: 50,000 times) of the film.

(2) Tensile modulus (MPa)

A sample was cut into a rectangular shape having a length of 150 mm and a width of 10 mm in the measurement direction, and stress-strain measurement was performed in an atmosphere of a temperature of 23 캜 and a humidity of 65% RH as follows. A tensile test was performed at an initial length of chuck of 50 mm and a tensile speed of 300 mm / min using Tensilon UCT-100 manufactured by ORIENTEC Co., and the first straight portion of the stress-strain curve was used, The tensile modulus was calculated by dividing the difference in stress by the difference in strain between two identical points. The measurement was carried out ten times in total, and the average value (rounded off to the first digit) was adopted. This was calculated for each of the longitudinal direction and the width direction.

(3) Tear strength (N / mm)

The tear strength measurement by the tracer thermal method was performed as follows according to JIS K 7128-1 (1998) in an atmosphere at a temperature of 23 캜 and a humidity of 65% RH. Measurement was carried out ten times in total at a test speed of 200 mm / min using Tensilon UCT-100 manufactured by ORIENTEC CORPORATION, and the average value (rounded off to the first decimal place) was adopted. This was calculated for each of the longitudinal direction and the width direction.

(4) Haze (%)

The haze value was measured according to the method defined in JIS K 7136 (2000) using a haze meter HGM-2DP manufactured by Suga Shikki Co., Ltd. The measurement was carried out five times by changing the measurement site with respect to one sample, and the average value (rounded off to the first decimal place) was adopted.

(5) Melt viscosity (Pa · s)

Co., Shimadzu Seisakusho CFT-500A flow tester manufactured by using a (die diameter of 1mm, a die length of 10mm, the plunger sectional area 1㎠), measured by the temperature 200 ℃, preheated three minutes, a shear rate of 100sec ^-1 melt viscosity of The value (Pa · s) (rounding the first digit) was adopted.

(6) Biomass ratio (%)

(% By mass) of the resin derived from biomass (rounded off to the first decimal place) when the entire resin composition constituting the film was taken as 100% by mass.

Very good: over 38%

Excellent: 25% to less than 38%

Good: Less than 5% and less than 25%

Bad: Less than 5%

(7) Weight average molecular weight Mw, number average molecular weight Mn

Is a value in terms of standard polymethylmethacrylate measured by gel permeation chromatography (GPC). GPC was measured by using Waters' differential refractometer Waters 410 as a detector, using MODEL510 high performance liquid chromatography of Waters Corporation as a pump, and connecting Shodex GPC HFIP-806M and Shodex GPC HFIP-LG in series to the column . The measurement conditions were a flow rate of 0.5 mL / min, 0.1 mL of a solution having a sample concentration of 1 mg / mL was injected using hexafluoroisopropanol as a solvent.

[Lactic acid resin (A)]

(A1)

Lactic acid, a mass average molecular weight Mw of 200,000, a D-isomer content of 1.4 mol%, a melting point of 166 캜, a temperature of 200 캜, a melt viscosity of 1,400 Pa · s at a shear rate of 100 sec ^-1 , and a biomass of 100%.

(A2)

L-lactic acid, mass average molecular weight Mw of 200,000, D-form content of 12.0 mol%, no melting point, melt temperature of 200 ° C, melt viscosity of 1,250 Pa · s at a shear rate of 100 sec ^-1 , and biomass of 100%.

(A3)

62 parts by mass of polyethylene glycol having a number average molecular weight Mn of 8,000, 38 parts by mass of L-lactide and 0.05 part by mass of tin octylate were mixed and polymerized at 160 DEG C for 3 hours in a reaction vessel equipped with a stirrer, A polylactic acid resin A3 having polylactic acid segments having a number average molecular weight Mn of 2,500 was obtained at both ends of a polyethylene glycol having a number average molecular weight Mn of 8,000. Biomass was also 39%.

(A4)

A mixture of 30 parts by mass of (A1) and 70 parts by mass of the above (A2) was supplied to a twin-screw extruder with a screw diameter of 44 mm at a cylinder temperature of 200 ° C and melted and kneaded while degassing the vacuum vent, To obtain a polylactic acid resin A4. The melt viscosity at a temperature of 200 ° C and a shear rate of 100 sec ^-1 was 1,300 Pa · s. The biomass degree was 100%.

(A5)

A mixture of 27 parts by mass of (A1), 63 parts by mass of (A2) and 10 parts by mass of (A3) was supplied to a twin-screw extruder equipped with a vacuum vent having a screw diameter of 44 mm at a cylinder temperature of 200 ° C, Kneaded, homogenized and then pelletized to obtain polylactic acid resin A5. The melt viscosity at a temperature of 200 캜 and a shear rate of 100 sec ^-1 was 1,000 Pa · s. Biomass ratio was 94%.

(A6)

A mixture of 24 parts by mass of (A1), 56 parts by mass of (A2) and 20 parts by mass of (A3) was supplied to a twin screw extruder equipped with a vacuum vent having a screw diameter of 44 mm at a cylinder temperature of 200 ° C, Kneaded, homogenized and then pelletized to obtain polylactic acid resin A6. The melt viscosity at a temperature of 200 캜 and a shear rate of 100 sec ^-1 was 700 Pa · s. Biomass was also 88%.

(A7)

A mixture of 21 parts by mass of (A1), 49 parts by mass of (A2) and 30 parts by mass of (A3) was fed to a twin screw extruder equipped with a vacuum vent having a screw diameter of 44 mm at a cylinder temperature of 200 ° C, Kneaded, homogenized and then pelletized to obtain polylactic acid resin A7. The melt viscosity at a temperature of 200 캜 and a shear rate of 100 sec ^-1 was 400 Pa · s. Biomass ratio was 82%.

(A8)

Poly-L- lactic acid, the weight average molecular weight Mw 200,000, D sieve content of 5.0mol%, melting point 150 ℃, 200 ℃ temperature, melt viscosity 1,400Pa · s, it is 100% of the biomass in the shear rate of 100sec ^-1.

[Biodegradable resin (B)]

(B1)

A polybutylene adipate terephthalate resin (trade name "ECOPLEX" FBX7011, manufactured by BASF Corporation), a melt viscosity of 1,200 Pa · s at a temperature of 200 ° C and a shear rate of 100 sec ^-1 .

(B2)

(Trade name "GS Pla" (registered trademark) AZ91T, manufactured by Mitsubishi Chemical Corporation), a melt viscosity of 1,050 Pa · s at a temperature of 200 ° C and a shear rate of 100 sec ^-1 .

(B3)

A polybutylene succinate adipate resin (trade name: Bionore 占 (registered trademark) # 3001, manufactured by Showa Kobunshi Co., Ltd.) having a melt viscosity of 1,250 Pa at a temperature of 200 캜 and a shear rate of 100 sec ^-1 · S.

(B4)

A polybutylene adipate terephthalate resin (trade name "ECOPLEX" FBX7020, manufactured by BASF), a melt viscosity of 650 Pa · s at a temperature of 200 ° C and a shear rate of 100 sec ^-1 .

[Commercialization agent (C)]

(C1)

Ethylene / acrylic ester / glycidyl acrylate copolymer ("BIOMAX" (registered trademark) Strong 120 manufactured by DuPont).

(C2)

Ethylene / acrylic acid ester / glycidyl methacrylate copolymer ("LOTADER" (registered trademark) AX8900 manufactured by ARAKEMASA).

(C3)

Epoxy group-containing styrene / acrylic acid ester copolymer ("JONCRYL" (registered trademark) ADR-4368 manufactured by BASF).

(C4)

Epoxy group-containing acrylic graft resin ("LEGEDA" (registered trademark) GP-301 manufactured by Toagosei Co., Ltd.).

(C5)

Ethylene / acrylic acid ester / maleic anhydride copolymer ("BONDINE" TX8030 manufactured by ARAKEMASA).

(C6)

Maleic anhydride-modified styrene / ethylene / butylene / styrene copolymer (KRATON (registered trademark) FG1924 manufactured by KURTON CORPORATION).

(C7)

Polycarbodiimide ("Carbodite" (registered trademark) LA-1 manufactured by Nissin Boseki Co., Ltd.).

(C8)

Magnesium acetate (anhydrous).

(C9)

Titanium tetraisopropoxide.

(C10)

p-toluenesulfonic acid.

(C11)

Hexamethylene diisocyanate.

[Production of biodegradable film]

(Comparative Example 1)

A mixture of 45 parts by mass of the polylactic acid resin (A1) and 55 parts by mass of the biodegradable resin (B1) was supplied to a twin screw extruder with a screw vent having a screw diameter of 45 mm and L / D = 32 at a cylinder temperature of 190 DEG C, The mixture was melted and kneaded while being degassed, homogenized and then pelletized to obtain a composition.

The pellets of this composition were vacuum-dried at 60 DEG C for 12 hours using a rotary drum type vacuum drier.

The pellets of this composition were fed to a uniaxial extruder having a screw diameter of 65 mm at an extruder cylinder temperature of 190 DEG C and extruded upward from a helical annular die having a diameter of 250 mm and a lip spacing of 1.4 mm and a temperature of 160 DEG C at a blow ratio of 2.8 The sheet was air-cooled by a cooling ring, pinched and rolled into a nip roll on the upper side of the die, cut at both ends with an edge cutter, and cut into two pieces. By adjusting the discharge amount and the drawing speed, a draw ratio 25 and a final thickness of 20 mu m were obtained. The physical properties of the obtained film are shown in Table 1.

In Examples 1 to 26 and Comparative Examples 2 to 5, a film having a final thickness of 20 占 퐉 was obtained in the same manner as in Comparative Example 1 except that the raw materials of the film and film forming conditions were changed as shown in Tables 1, 2 and 3 . Physical properties of the obtained film are shown in Tables 1, 2, 3 and 4.

&Lt; Industrial applicability >

The biodegradable film of the present invention is a biodegradable film which is excellent in flexibility, durability and transparency, is excellent in biomass property, and particularly exhibits a good effect in the inflation film forming method, and is a biodegradable film mainly having flexibility For agricultural use such as agricultural multi-film, pine mushroom fumigation sheet, compost bag, food packaging such as vegetable or fruit, medical packaging, shopping bag, garbage bag, It can be suitably used for a bag of various industrial products.

A: Dispersion phase
B: Continuous phase

Claims (8)

A biodegradable film comprising a lactic acid resin (A) and a biodegradable resin (B) other than the lactic acid resin (A), wherein the biodegradable resin (B) (A) is dispersed in a long oval phase in the longitudinal direction of the film or in a long layer in the longitudinal direction of the film in a continuous phase in which the lactic acid resin (A) and the biodegradable resin in total 100% by weight of (B), the lactic acid resin (a) content (mass%) of P _a, the content (mass%) of the biodegradable resin (B), P _B, the thickness (nm) of the disperse phase of Satisfies the following formula when W _A is the thickness of the continuous film and W _B is the thickness (nm) of the continuous film.
W _A / W _B &_amp;le; 2.0 x P _A / P _B The biodegradable film according to claim 1, wherein the dispersed phase has a thickness W _A of 5 to 100 nm. The biodegradable film according to claim 1 or 2, wherein the tear strength of the film by the thermal method as defined in JIS K7128-1 (1998) is not less than 5 N / mm in both longitudinal and transverse directions. The biodegradable film according to claim 1 or 2, wherein P _A : P _B = 5: 95 to 60:40. According to claim 1 or 2 wherein the temperature 200 ℃, the melt viscosity of the lactic acid resin (A) of the shear rate of 100 sec ^-1 η _A, temperature 200 ℃, biodegradation of the shear rate of 100 sec ^-1 And a melt viscosity of the resin (B) is? _B , the following formula is satisfied.
0.3?? _A /? _B ? The biodegradable film according to claim 1 or 2, wherein the biodegradable film contains a compatibilizer. The positive resist composition according to claim 1 or 2, wherein the lactic acid resin (A) is selected from the group consisting of a block copolymer having a polyether segment and a polylactic acid segment, and a block copolymer having a polyester segment and a polylactic acid segment Wherein the biodegradable film comprises at least one and homopolylactic acid. The biodegradable resin composition according to claim 1 or 2, wherein the biodegradable resin (B) is at least one selected from the group consisting of polybutylene succinate, polybutylene succinate adipate, and polybutylene adipate / terephthalate Sex Film.

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