JPWO2016158736A1 - Biodegradable white film and method for producing the same - Google Patents

Abstract

The present invention provides a biodegradable white film excellent in moisture permeability, flexibility, concealability, mechanical properties, and processability. The biodegradable white film of the present invention includes a biodegradable resin A and a filler B, and the filler B is a filler b1 which is a filler having void forming ability and a filler having a high refractive index. When the content of the filler b1 is Wb1 and the content of the filler b2 is Wb2, the Wb1 + Wb2 is 3 parts by mass or more and 25 parts by mass or less with respect to 100 parts by mass of the biodegradable resin A. Yes, Wb1 / Wb2 is 2 or more and 20 or less.

Description

  The present invention relates to a biodegradable white film excellent in moisture permeability, flexibility, concealability, mechanical properties, and processability.

  In recent years, with increasing environmental awareness, attention has been focused on soil pollution problems caused by the disposal of plastic products and global warming problems caused by increased carbon dioxide caused by incineration. As a countermeasure against the former, various biodegradable resins have been studied, and as a countermeasure against the latter, resins made of biomass (plant-derived raw materials) that do not give a new carbon dioxide load to the atmosphere even when incinerated are popular. Has been researched and developed.

  As a resin that satisfies both requirements and is relatively advantageous in terms of cost, for example, a polylactic acid resin has attracted attention. When polylactide resin is used as a substitute for flexible film applications such as polyethylene resin such as polyethylene, it lacks concealability, flexibility, and impact resistance, so these characteristics can be improved and put to practical use. Various attempts have been made.

  For example, Patent Document 1 discloses a porous sheet obtained by at least uniaxially stretching a sheet containing a polylactic acid resin, a filler, and a general polyester plasticizer, and a method for producing the same. While adding flexibility by adding a thermoplastic resin other than the base resin, a large amount of particles are added, and the mixture is stretched at a high magnification to make it porous. Patent Document 2 discloses a porous film obtained by stretching a sheet containing a polylactic acid resin, a thermoplastic resin other than the polylactic acid resin, and a filler.

  In Patent Document 3, when a resin composition containing a biodegradable polyester resin, a filler, and a plasticizer is melt-molded, a first cooling step and a second cooling step are performed, and then A method for producing a stretched porous sheet is disclosed, and a method for obtaining a film imparted with moisture permeability by adding a large amount of particles and making it porous by stretching is disclosed.

International Publication No. 2012/023465 Japanese Unexamined Patent Publication No. 2007-112867 Japanese Unexamined Patent Publication No. 2009-144105

  However, in the techniques described in Patent Documents 1 and 2 described above, although a porous film excellent in flexibility and moisture permeability can be obtained, performance such as concealment is not sufficient. Specifically, in the inventions described in Patent Documents 1 and 2, a film having sufficient flexibility and high moisture permeability can be obtained, but after adding a large amount of particles, longitudinal and transverse biaxial stretching is performed at a high magnification. Therefore, there are problems that tearing is likely to occur during film formation and that the range of film forming conditions is narrow. Also, the obtained film has poor mechanical properties, and there is a problem that the impact resistance, flexibility, and concealment properties are insufficient. As a result, it is easy to deform during continuous processing at high speed for the purpose of improving productivity, making it difficult to transport. Especially, the mechanical properties in the width direction of the film are poor, so it tears and breaks when processing such as transport and cutting. There are problems such as being easy to do.

  In the invention described in Patent Document 3, flexibility has been studied, but it has not been possible to impart a level of flexibility equivalent to that of polyolefin, which is a representative material of a practically preferable soft film.

  That is, the invention of a film having a high biomass degree that is excellent in concealability, mechanical properties, and processability in addition to sufficient moisture permeability and flexibility has not yet been achieved.

  This invention makes it the subject to provide the biodegradable white film excellent in moisture permeability, a softness | flexibility, concealability, a mechanical characteristic, and workability in view of the background of the prior art which concerns.

In order to solve the above problems, the present invention has the following configuration.
1) A biodegradable white film containing a biodegradable resin A and a filler B, wherein the filler B is a filler b1 having a void forming ability and a high refractive index filler. When the content of the filler b1 is Wb1 and the content of the filler b2 is Wb2, Wb1 + Wb2 is 3 parts by mass or more and 25 parts by mass with respect to 100 parts by mass of the biodegradable resin A. A biodegradable white film having a mass part or less and Wb1 / Wb2 of 2 or more and 20 or less.
2) The biodegradation according to 1), wherein the filler b1 is at least one of calcium carbonate and barium sulfate, and the filler b2 is at least one of titanium oxide and zinc oxide. White film.
3) When the Young's modulus (GPa) in the direction where the Young's modulus is the largest (direction a) is Ea and the Young's modulus in the direction (direction b) perpendicular to the same plane as the direction a is Eb, Ea / Eb is 1 The biodegradable white film according to 1) or 2), which has a breaking elongation in the direction b of 100% or more and 500% or less.
4) The biodegradable white film according to any one of 1) to 3), wherein the biodegradable resin A includes a polylactic acid resin.
5) When the biodegradable resin A includes a polylactic acid resin and a biodegradable resin other than the polylactic acid resin, and the biodegradable resin A is 100% by mass, the polylactic acid resin Any one of 1) to 4), wherein the content is 10% by mass to 95% by mass, and the content of the biodegradable resin other than the polylactic acid resin is 5% by mass to 90% by mass. The biodegradable white film described in 1.
6) A biodegradable resin other than the polylactic acid resin is a block copolymer having a polyether segment and a polylactic acid segment, a block copolymer having a polyester segment and a polylactic acid segment, and an aliphatic polyester resin. The biodegradable white film as described in 5) above, which is at least one resin selected from the group consisting of a resin and an aliphatic aromatic polyester resin.
7) Any one of the above 1) to 6), wherein the Young's modulus Ea in the direction where the Young's modulus is the largest (direction a) is 1.5 GPa or less, and the surface free energy of at least one side surface is 70 mN / m or less. The biodegradable white film described in 1.
8) A biodegradable white film containing a biodegradable resin A and a filler B, wherein the Young's modulus (GPa) in the direction (direction a) having the largest Young's modulus is Ea and in the same plane as direction a When the Young's modulus in the orthogonal direction (direction b) is Eb, Ea is 2 GPa or less, Ea / Eb is 1.2 or more and 2.5 or less, and the elongation at break in direction b is 100% or more. A biodegradable white film.
9) The biodegradable white film according to 8), wherein the biodegradable resin A includes a polylactic acid resin.
10) When the biodegradable resin A includes a polylactic acid resin and a biodegradable resin other than the polylactic acid resin, and the biodegradable resin A is 100% by mass, the polylactic acid resin The content of is 10% by mass or more and 95% by mass or less, and the content of biodegradable resin other than the polylactic acid resin is 5% by mass or more and 90% by mass or less. Biodegradable white film.
11) A biodegradable resin other than the polylactic acid resin is a block copolymer having a polyether segment and a polylactic acid segment, a block copolymer having a polyester segment and a polylactic acid segment, and an aliphatic polyester resin. The biodegradable white film as described in 10) above, which is at least one resin selected from the group consisting of a resin and an aliphatic aromatic polyester resin.
12) The biodegradable white film according to any one of 8) to 11), wherein the filler B is contained in an amount of 1 part by mass to 50 parts by mass with respect to 100 parts by mass of the biodegradable resin A.
13) The biodegradable white film as described in any one of 8) to 12) above, wherein the surface free energy of at least one surface is 70 mN / m or less.
14) A melt-kneading step for obtaining a resin composition by melt-kneading the biodegradable resin A and the filler B, and a melt-extruding step for obtaining an unstretched film by melting the resin composition and discharging it from a die. The biodegradation according to any one of 1) to 13) above, further comprising a stretching step for stretching the unstretched film in at least one direction to obtain a stretched film, and a heat treatment step for heating the stretched film in this order. In the stretching step, when the melting point of the biodegradable resin A is Tm (° C), in the range of Tm-160 (° C) or more and Tm-95 (° C) or less, A method for producing a biodegradable white film, which is stretched 1.5 to 4 times.

  According to the present invention, a biodegradable white film excellent in moisture permeability, flexibility, concealability, mechanical properties, and processability can be provided.

Hereinafter, the biodegradable white film of the present invention and the production method thereof will be described in detail.
In the present specification, all percentages and parts expressed by mass are the same as percentages and parts expressed by weight.

  The first biodegradable white film according to the first embodiment of the present invention is a biodegradable white film containing a biodegradable resin A and a filler B, and the filler B has a void-forming ability. When the filler b1 is a filler having a refractive index and the filler b2 is a filler having a high refractive index, the content of the filler b1 is Wb1, and the content of the filler b2 is Wb2. Wb1 + Wb2 is 3 to 25 parts by mass and Wb1 / Wb2 is 2 to 20 with respect to 100 parts by mass of the biodegradable resin A. Hereinafter, the first biodegradable white film may be referred to as the first biodegradable white film of the present invention or the first present invention.

  The second biodegradable white film according to the second embodiment of the present invention is a biodegradable white film containing the biodegradable resin A and the filler B, and has the largest Young's modulus (direction a). ) Is Ea, and Young's modulus in the direction (direction b) perpendicular to the same plane as the direction a is Eb, Ea is 2 GPa or less, and Ea / Eb is 1.2 or more and 2 0.5 or less, and the elongation at break in the direction b is 100% or more. Hereinafter, the second biodegradable white film may be referred to as the second biodegradable white film of the present invention or the second present invention.

  The first biodegradable white film of the present invention and the second biodegradable white film of the present invention are collectively referred to as the biodegradable white film of the present invention.

  Although the desirable form for implementing this invention is demonstrated below, this invention is not limited to this.

  The first biodegradable white film of the present invention includes a biodegradable resin A and a filler B, and the filler B is a filler having a void forming ability and a high refractive index filling. When the content of the filler b1 is Wb1 and the content of the filler b2 is Wb2, Wb1 + Wb2 is 3 masses with respect to 100 parts by mass of the biodegradable resin A. It is important that it is not less than 25 parts by mass and Wb1 / Wb2 is not less than 2 and not more than 20.

  In addition, the second biodegradable white film of the present invention includes the degradable resin A and the filler B, and has the same Young's modulus (GPa) in the direction (direction a) in which the Young's modulus is the largest as in Ea and direction a. Eb is 2 GPa or less, Ea / Eb is 1.2 or more and 2.5 or less, and the elongation at break in direction b is Eb when the Young's modulus in the direction perpendicular to the surface (direction b) is Eb. It is important that is 100% or more.

  In the biodegradable white film of the present invention, it is important that the haze measured based on JIS-K7136 (2000) is 70% or more. In the present invention, a film having a haze of 70% or more is referred to as a white film. By setting the haze to 70% or more, for example, when the first biodegradable white film of the present invention is used for packaging materials, sanitary materials, etc., it is possible to prevent see-through of inclusions and filth, and good appearance It can be. The upper limit of haze is not particularly limited, but is substantially 99.9% or less.

  It is important that the biodegradable white film of the present invention contains the biodegradable resin A. The biodegradable resin A is not particularly limited as long as it is a biodegradable resin. The “resin having biodegradability” in the present invention means JIS K6950 (2000 version), JIS K6951 (2000 version), JIS K6953-1 (2011 version), JIS K6953-2 (2010 version), JIS. When tested with any of K6955 (2006 edition), it means a resin that produces degradation of 60% or more within one year.

  Examples of the biodegradable resin A include aliphatic polyester resins, aliphatic aromatic polyester resins, polysaccharides, polyvinyl alcohol resins, starch-containing polymers, and block copolymers described later.

  Specific examples of the aliphatic polyester resin include polylactic acid resin, polyglycolic acid, poly (3-hydroxybutyrate), poly (3-hydroxybutyrate / 3-hydroxyhexanoate), and poly (3-hydroxy Butyrate 3-hydroxyvalerate), polycaprolactone, polybutylene succinate, poly (butylene succinate adipate) and the like.

  Specific examples of the aliphatic aromatic polyester resin include poly (ethylene succinate / terephthalate), poly (butylene succinate / terephthalate), and poly (butylene adipate / terephthalate).

  Specific examples of the polysaccharide include cellulose resins such as cellulose acetate and glucosamine resins such as chitosan.

  Specific examples of the polymer containing starch include thermoplastic starch and starch-based biodegradable resins such as Novamont's biodegradable resin “Matter-Bi” (registered trademark).

  Among these, it is preferable that the biodegradable resin A contains a polylactic acid resin from the viewpoint of biomass, cost, processability, etc., and a mixture of a crystalline polylactic acid resin and an amorphous polylactic acid resin It is more preferable to contain. As a commercial item of a polylactic acid-type resin, "Ingeo" (trademark) Biopolymer made from Nature Works is mentioned, for example. By containing the crystalline polylactic acid-based resin, the shape retention, heat resistance, and blocking resistance of the film are improved.

  The polylactic acid-based resin refers to a polymer having an L-lactic acid unit and / or a D-lactic acid unit as main constituent components. Here, the main constituent component is L-lactic acid in 100% by mass of the polymer. It means that the mass ratio of the whole lactic acid unit (hereinafter sometimes referred to as all lactic acid unit or simply lactic acid unit) including the unit and the D-lactic acid unit exceeds 50%. From the viewpoint of biomass, the mass ratio of the lactic acid unit is more preferably 70% by mass or more and 100% by mass or less when the entire polymer is 100% by mass. Of polylactic acid-based resins, when the total lactic acid unit in the polymer is 100 mol%, the L-lactic acid unit content is more than 50 mol% and not more than 100 mol% is called poly L-lactic acid. When the total lactic acid unit in the coalescence is 100 mol%, the content ratio of the D-lactic acid unit is more than 50 mol% and not more than 100 mol% is called poly D-lactic acid.

  The polylactic acid-based resin includes a block copolymer having a polyether-based segment and a polylactic acid-based segment described in Biodegradable resin (biodegradable resin a) other than the polylactic acid-based resin described later, polyester A block copolymer having a polymer segment and a polylactic acid segment is not included.

  The crystalline polylactic acid-based resin is a polylactic acid-based resin that is allowed to stand at a temperature of 100 ° C. for 24 hours, and then subjected to a differential scanning calorimeter (DSC) at a temperature rising rate of 20 ° C./min at 25 to 250 ° C. When the measurement is performed, it means a polylactic acid resin in which a crystal melting peak derived from the polylactic acid component is observed. An amorphous polylactic acid-based resin refers to a polylactic acid-based resin in which a clear melting point is not observed when measured under the same conditions.

  In poly L-lactic acid, the crystallinity of the resin itself varies depending on the content ratio of the D-lactic acid unit. Specifically, when the content ratio of the D-lactic acid unit in the poly-L-lactic acid increases, the crystallinity of the poly-L-lactic acid decreases and approaches an amorphous state. If the content ratio of the lactic acid unit is decreased, the crystallinity of poly L-lactic acid is increased. Similarly, the crystallinity of the resin itself also changes depending on the content ratio of the L-lactic acid unit. Specifically, 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 is lowered and approaches an amorphous state, and conversely, the L-lactic acid in the poly-D-lactic acid. If the content rate of a unit becomes small, the crystallinity of poly D-lactic acid will become high.

  The content ratio of the L-lactic acid unit in the poly L-lactic acid of the present invention or the content ratio of the D-lactic acid unit in the poly D-lactic acid of the present invention is from the viewpoint of maintaining the mechanical properties of the biodegradable white film. When the total lactic acid unit is 100 mol%, it is preferably 80 mol% or more and 100 mol% or less, and more preferably 85 mol% or more and 100 mol% or less.

  The polylactic acid resin may be a copolymer obtained by copolymerizing lactic acid and other monomer units other than lactic acid. Here, as other monomer units, ethylene glycol, propylene glycol, butanediol, heptanediol, hexanediol, octanediol, nonanediol, decanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, glycerin, Glycol compounds such as pentaerythritol, bisphenol A, polyethylene glycol, polypropylene glycol and polytetramethylene glycol, oxalic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, malonic acid, glutaric acid, cyclohexanedicarboxylic acid, terephthalic acid, Isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, bis (p-carboxyphenyl) methane, anthracene dicarboxylic acid, 4,4′-diphenyl ether Dicarboxylic acids such as dicarboxylic acid, 5-sodium sulfoisophthalic acid, 5-tetrabutylphosphonium isophthalic acid, glycolic acid, hydroxypropionic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxycaproic acid, hydroxybenzoic acid and other hydroxycarboxylic acids, caprolactone And lactones such as valerolactone, propiolactone, undecalactone, and 1,5-oxepan-2-one. In addition, when using the biodegradable white film of this invention for the use which needs biodegradability, it is preferable to select the component which has biodegradability among the above-mentioned monomer units.

  From the viewpoint of maintaining the mechanical properties of the biodegradable white film, the amount of copolymerization of the other monomer units is 100 mol% when the entire monomer unit in the polymer of the polylactic acid resin is 100 mol%. It is preferably 0 mol% or more and 30 mol% or less, and more preferably 0 mol% or more and 10 mol% or less.

  The polylactic acid-based resin may be a mixture of poly D-lactic acid when the main component is poly L-lactic acid, and a mixture of poly L-lactic acid when the main component is poly D-lactic acid. This is a preferred embodiment from the viewpoint of improving the heat resistance of the degradable white film. The amount of poly-D-lactic acid or poly-L-lactic acid to be mixed is preferably 20% by mass or more and less than 50% by mass, and 30% by mass when the total of the polylactic acid-based resins in the biodegradable white film is 100% by mass. % To less than 50% by mass is more preferable. When poly D-lactic acid or poly L-lactic acid is mixed in this way, a stereocomplex crystal is formed, and this stereocomplex crystal has a higher melting point than a normal polylactic acid crystal (α crystal). The heat resistance of the film is improved. The main component here means a component (poly L-lactic acid or poly D-lactic acid) exceeding 50% by mass when the total of the polylactic acid-based resins in the biodegradable white film is 100% by mass. means.

  The weight average molecular weight of the polylactic acid resin used in the biodegradable white film of the present invention is 50,000 or more and 240 from the viewpoint of satisfying the practical mechanical properties, water resistance, and degradability of the biodegradable white film. , 000 or less, more preferably 60,000 or more and 200,000 or less, and particularly preferably 70,000 or more and 160,000 or less. The mass average molecular weight as used herein refers to a molecular weight obtained by measuring by gel permeation chromatography (GPC) using a chloroform solvent and calculating by a polymethyl methacrylate conversion method.

  In the biodegradable white film of the present invention, when the total of the polylactic acid resin is 100% by mass (when the total of the crystalline polylactic acid resin and the amorphous polylactic acid resin is 100% by mass), The mass ratio of the crystalline polylactic acid-based resin is preferably 5% by mass or more and 60% by mass or less, more preferably 10% by mass or more and 50% by mass or less, and 20% by mass or more and 40% by mass or less. Is more preferable.

  The biodegradable white film of the present invention contains a polylactic acid resin and a biodegradable resin other than the polylactic acid resin (hereinafter referred to as biodegradable resin a) from the viewpoint of improving moisture permeability and degradability. Is more preferable.

  Examples of the biodegradable resin a include aliphatic polyester resins other than polylactic acid resins, aliphatic aromatic polyester resins, polysaccharides, polymers containing starch, polyvinyl alcohol resins, polyacetals, polyethylenes, polypropylenes, polyamides , Poly (meth) acrylate, polyphenylene sulfide, polyether ether ketone, polyester, polyurethane, polyisoprene, polysulfone, polyphenylene oxide, polyimide, polyetherimide, epoxy-modified polyolefin, acid-modified polyolefin, olefin-acrylic copolymer, epoxy-modified Olefin-acrylic copolymer, polyester elastomer, polyamide elastomer, polyolefin elastomer, polyether segment and poly milk Block copolymer having polyester segments, block copolymer having polyester segments and polylactic acid segments, polyester plasticizers such as polypropylene glycol sebacate, polyalkylene ether plasticizers, ether ester plasticizers and acrylates A plasticizer or the like can be used.

  As the biodegradable resin a, it is preferable to use a resin having excellent biodegradability from the viewpoint of maintaining the biodegradability of the entire biodegradable white film. Furthermore, from the viewpoint of the bleed-out resistance of the plasticizer, the heat resistance of the stretched film, and the blocking resistance, it should be solid at room temperature (20 ° C. ± 15 ° C.), that is, having a melting point exceeding 35 ° C. preferable. Moreover, from the viewpoint of adjusting the melt processing temperature with the polylactic acid resin, it is preferable to use one having a melting point of 150 ° C. or lower.

  From the above three viewpoints, the biodegradable resin a is a block copolymer having a polyether-based segment and a polylactic acid-based segment, a block copolymer having a polyester-based segment and a polylactic acid-based segment, and a polylactic acid-based resin. More preferably, it is at least one resin selected from the group consisting of an aliphatic polyester-based resin and an aliphatic aromatic polyester-based resin. The aliphatic polyester resin is particularly preferably polybutylene succinate, and the aliphatic aromatic polyester resin is particularly preferably poly (butylene adipate / terephthalate). Of these, polybutylene succinate is most preferable. The at least one resin means that these resins may be used alone or in combination.

  In addition, as a biodegradable resin (biodegradable resin a) other than the polylactic acid-based resin, a block copolymer having a polyether-based segment and a polylactic acid-based segment described later, and a block having a polyester-based segment and a polylactic acid-based segment When a copolymer is used, the crystalline polylactic acid-based resin exhibits a great effect on the bleed-out resistance by forming a eutectic with the polylactic acid-based segment of these block copolymers. On the other hand, the inclusion of an amorphous polylactic acid resin as the polylactic acid resin is suitable for improving the moisture permeability, flexibility, and bleed-out resistance of the film. The influence is that a block copolymer having a polyether-based segment and a polylactic acid-based segment, and an amorphous portion in which the block copolymer having a polyester-based segment and a polylactic acid-based segment can be dispersed are provided.

  When the biodegradable white film of the present invention includes a polylactic acid-based resin and a biodegradable resin a, from the viewpoint of biomass, when the biodegradable resin A is 100% by mass, the polylactic acid-based resin is contained. The amount is preferably 10% by mass or more and 95% by mass or less, the content of the biodegradable resin a is preferably 5% by mass or more and 90% by mass or less, and the content of the polylactic acid resin is 20% by mass or more and 70% by mass. More preferably, the content of the biodegradable resin a is 30% by mass or more and 80% by mass or less.

  The content of the biodegradable resin a here means the total amount of the plurality of biodegradable resins a when a plurality of components are contained as the biodegradable resin a. When the biodegradable resin a is an aliphatic polyester resin and / or an aliphatic aromatic polyester resin, the total amount of the aliphatic polyester resin and the aliphatic aromatic polyester resin is more preferably 10% by mass or more and 60%. It is 20 mass% or less, More preferably, it is 20 mass% or more and 50 mass% or less. Moreover, when the biodegradable resin a is a block copolymer, it is 10 to 50 mass%, More preferably, it is 15 to 40 mass%.

  It is important that the biodegradable white film of the present invention contains the filler B. Filler B refers to a substance added as a base material for improving various properties, or an inert substance added for the purpose of increasing the amount, increasing the volume, reducing the cost of the product, or the like.

  In the first biodegradable white film of the present invention, from the viewpoint of improving moisture permeability and concealing properties and maintaining mechanical properties such as strength and elongation, the filler B has a void forming ability (hereinafter referred to as a filler). The filler b1), and a high refractive index filler (hereinafter also referred to as the filler b2). Here, the filler having void forming ability refers to a filler having a ratio of the total area of voids to a cross-sectional area of the entire film measured by the following procedure of 5% or more.

  First, the biodegradable resin A used for the production of the film was formed into a sheet by containing a filler at a concentration of 20% by mass, and then the sheet was 4 at a glass transition temperature of the biodegradable resin A + 10 ° C. A uniaxially stretched film obtained by stretching the film in a uniaxial direction was cut along a plane parallel to the stretching direction and perpendicular to the film surface, and a cross-sectional photograph magnified 3000 times with a scanning microscope was taken. Subsequently, after measuring the mass (X) of the film part of the obtained cross-sectional photograph, the part which can be visually recognized as a space | gap was cut out from the cross-sectional photograph using the cutter etc., and the mass (Y) was measured. Finally, the value of Y was divided by the value of X to calculate the ratio of the total area of the voids to the cross-sectional area of the entire film. In addition, the glass transition temperature of the biodegradable resin A here refers to the highest glass transition temperature when the biodegradable resin A exhibits a plurality of glass transition temperatures. Examples of the filler b1 include calcium carbonate, barium sulfate, aluminum oxide, and silicon oxide. The filler b1 can be used alone or in combination of two or more.

  A high refractive index filler refers to a filler having a refractive index of 2.0 or more. The refractive index referred to here is the refractive index described in the Inorganic Chemistry Handbook (Gihodo 1965), and those shown in the range are the refractive index in the present application with the higher value. Specifically, as the filler b2, for example, rutile type titanium oxide (refractive index: 2.90), anatase type titanium oxide (refractive index: 2.50), zinc oxide (refractive index: 2.00), Examples include lead titanate (refractive index: 2.70), zinc sulfide (refractive index: 2.37), zirconium oxide (refractive index: 2.40), and the like. The filler b2 can be used alone or in combination of two or more. The refractive index of the filler B not described in the above inorganic chemistry handbook is the intensity distribution of diffracted / scattered light measured by a laser diffraction particle size distribution analyzer SALD-2300 (manufactured by Shimadzu Corporation). From the pattern, the refractive index value is calculated by the light intensity reproduction method using data analysis software WingSALDII (manufactured by Shimadzu Corporation).

  A material having void forming ability and a refractive index of 2.0 or more is designated as filler b1.

  By containing the filler b1, the film can be appropriately made porous so that the moisture permeability of the film can be improved. By containing the filler b2, the concealability of the film is improved, and the strength and elongation are increased. Mechanical properties such as degrees can be maintained.

  From the viewpoints of improving the moisture permeability of the film, maintaining mechanical properties such as strength and elongation, imparting whiteness, and reducing costs, the filler b1 may be at least one of calcium carbonate and barium sulfate. preferable. Further, from the viewpoint of maintaining mechanical properties such as strength and elongation, imparting whiteness, and reducing cost, the filler b2 is preferably at least one of titanium oxide and zinc oxide.

  In the first biodegradable white film of the present invention, the content of the filler b1 is Wb1 and the content of the filler b2 from the viewpoint of improving moisture permeability and concealment and maintaining mechanical properties such as strength and elongation. When the amount is Wb2, it is important that Wb1 + Wb2 is 3 to 25 parts by mass and Wb1 / Wb2 is 2 to 20 with respect to 100 parts by mass of the biodegradable resin A.

  By setting Wb1 + Wb2 to 3 parts by mass or more, it becomes possible to improve the concealability of the film, and by setting it to 25 parts by mass or less, the mechanical properties of the film can be maintained. More preferably, they are 10 mass parts or more and 20 mass parts or less, Furthermore, they are 15 mass parts or more and 20 mass parts. Further, by setting Wb1 / Wb2 to 2 or more, it is possible to increase the moisture permeability of the film, and by setting Wb1 / Wb2 to 20 or less, it is possible to maintain mechanical characteristics. More preferably, it is 5 or more and 20 or less.

  The second biodegradable white film of the present invention preferably contains 1 part by mass or more and 50 parts by mass or less of the filler B. More preferably, it is 3 parts by weight or more and 25 parts by weight or less, more preferably 10 parts by weight or more and 20 parts by weight or less, and further preferably 15 parts by weight or more and 20 parts by weight or less. It may be used, or may be a blend of two or more of the above. In particular, when the filler is combined as the filler B, a filler that imparts a necessary function to the film can be selected depending on the purpose. When the filler B is a blend of two or more kinds, the film can be appropriately made porous by including the filler b1 to improve moisture permeability, and the whiteness, concealment, and reflection can be improved by including the filler b2. Since the film has higher properties, it becomes possible to achieve both moisture permeability and mechanical properties such as strength and elongation.

  The average particle diameter of the filler B is not particularly limited as long as the effects of the present invention are not impaired, but from the viewpoint of improving the moisture permeability of the film, preferably 0.01 μm or more and 10 μm or less, more preferably 0.1 μm or more and 8 μm or less, It is more preferably 0.5 μm or more and 5 μm or less, and particularly preferably 1 μm or more and 3 μm or less. By making the average particle diameter of the filler B 0.01 μm or more, the filler can be highly filled in the film, and by making the average particle diameter of the filler B 10 μm or less, the stretchability of the film Becomes better. As a result, the film becomes porous and has excellent moisture permeability. Here, the average particle diameter is a 50% cumulative distribution average particle diameter measured by a laser diffraction scattering method.

  The filler B of the present invention has at least one functional group selected from a hydroxyl group, an amino group, an amide group, a carboxyl group, a glycidyl group, an acid anhydride group, a carbodiimide group, and an oxazoline group as necessary. It can be surface treated with a compound. By performing the surface treatment, the affinity with the biodegradable resin is improved, which is effective in suppressing the aggregation of the filler and improving the dispersibility, and can be uniformly dispersed in the resin composition.

  Moreover, in this invention, in order to improve the dispersibility of the filler B in a resin composition, it is preferable to add a dispersing agent further.

  The biodegradable white film of the present invention may contain additives other than those described above as long as the effects of the present invention are not impaired. For example, known antioxidants, crystal nucleating agents, organic lubricants, UV stabilizers, endblockers, anti-coloring agents, matting agents, antibacterial agents, deodorants, flame retardants, weathering agents, antistatic agents, Oxidizing agents, ion exchangers, tackifiers, antifoaming agents, color pigments, dyes and the like can be used.

  In addition, the biodegradable white film of the present invention may be added with a small amount of a thermoplastic elastomer C other than the biodegradable resin A. The surface free energy may be set to 70 mN / m or less to adhere closely to other materials. It is preferably performed in order to improve the property. The thermoplastic elastomer C other than the biodegradable resin A is a polymer that exhibits a thermoplastic property when heated to a melting point or higher, while exhibiting a rubber elastic property at room temperature. A resin that produces less than 60% degradation within a year. Specific examples include polyester elastomers, polystyrene elastomers, polyolefin elastomers, polyamide elastomers, and acrylic elastomers. In particular, when a polylactic acid-based resin is selected as the biodegradable resin A, an acrylic elastomer is preferable because dispersibility is good and adhesion is improved. Examples of the acrylic elastomer that can be preferably used for the biodegradable white film of the present invention include “Clarity” (registered trademark) manufactured by Kuraray Co., Ltd.

  The content of the thermoplastic elastomer C other than the biodegradable resin A is preferably 1 part by mass or more and 30 parts by mass or less, more preferably 2 parts by mass with respect to 100 parts by mass of the biodegradable resin A content. It is 25 parts by mass or less, particularly preferably 5 parts by mass or more and 20 parts by mass or less.

  Furthermore, in order to further improve biodegradability and adhesion, the biodegradable white film of the present invention does not contain a thermoplastic elastomer with respect to 100 parts by mass of the biodegradable resin A in the layer, or The layer contains more than 0 parts by weight and less than 5 parts by weight (layer 1) and 100 parts by weight of the biodegradable resin A in the layer. More than 25 parts by mass, particularly preferably 5 parts by mass or more and 20 parts by mass or less (layer 2) including a layered structure, layer 2 contains more thermoplastic elastomer than layer 1, and at least one side surface layer is a layer The aspect which is 2 is more preferable. Among these, an embodiment in which the layer 2 is on the outermost surfaces on both sides of the film is more preferable. Here, when the layer 2 contains more thermoplastic elastomer than the layer 1, the content (parts by mass) of the thermoplastic elastomer in the layer 2 when the biodegradable resin A in the layer 2 is 100 parts by mass, When the biodegradable resin A in the layer 1 is 100 parts by mass, it means that the thermoplastic elastomer content (part by mass) in the layer 1 is larger.

  The first biodegradable white film of the present invention has the same Young's modulus (GPa) in the direction (direction a) with the largest Young's modulus as Ea and the direction a from the viewpoint of suppressing deformation in continuous processing at high speed. When the Young's modulus in the direction perpendicular to the plane (direction b) is Eb, Ea / Eb is preferably 1.2 or more and 2.5 or less, more preferably 1.3 or more and 2.3 or less. Preferably, it is 1.3 or more and 2.0 or less.

  Moreover, as for the 2nd biodegradable white film, as for the biodegradable white film of this invention, it is important that Ea / Eb is 1.2-2.5. Ea / Eb is more preferably 1.3 or more and 2.0 or less. By making Ea / Eb 1.2 or more and 2.5 or less, it becomes possible to suppress the deformation | transformation in continuous processing at high speed, and a conveyance property can be provided.

  Generally, when the film is stretched, the Young's modulus in the stretched direction increases, so the direction with the largest Young's modulus is usually the direction with the highest stretch ratio. That is, the direction a is the direction with the highest draw ratio.

  The method of setting Ea / Eb to 1.2 or more and 2.5 or less is not particularly limited as long as the effect of the present invention is not impaired. For example, a method of stretching an unstretched film only in one direction, or an unstretched film orthogonal The method of extending | stretching by different magnification in two directions to perform is mentioned. Especially, the method of extending | stretching an unstretched film only to one direction is more preferable from a viewpoint of adjusting Ea / Eb easily with few processes. When the unstretched film is stretched in one direction, Ea / Eb can be increased by increasing the stretch ratio. Moreover, when extending | stretching an unstretched film to two directions orthogonal, Ea / Eb can be enlarged by enlarging the difference of a draw ratio.

It is important that the second biodegradable white film has an Ea of 2 GPa or less. Here, the direction in which the Young's modulus is the largest (direction a) is the direction in which the Young's modulus of the film is measured by changing the direction every 10 ° in the film plane, and the obtained value is maximized. .
Ea is more preferably 1.5 GPa or less, and still more preferably 1.0 GPa or less. The lower limit is not particularly limited, but is substantially 0.5 GPa or more. By setting the Young's modulus of Ea to 2 GPa or less, the sharp feeling peculiar to polylactic acid can be suppressed, and it can be suitably used for various applications.

  From the same viewpoint, the first biodegradable white film preferably has an Ea of 2 GPa or less, more preferably 1.5 GPa or less, and even more preferably 1.0 GPa or less. Although there is no restriction | limiting in particular about a minimum, it is 0.5 GPa or more substantially.

  The method for setting the Young's modulus Ea in the direction a to 2 GPa or less is not particularly limited, but the polylactic acid resin and the biodegradable resin a are used in combination as the biodegradable resin A, and the type and content thereof are described above. In the manufacturing method to be described later, the ratio in the stretching step is preferably set in a preferable range. A combination of a plurality of these methods is also preferably performed.

  The biodegradable white film of the present invention preferably has a breaking elongation in the direction b of 100% or more, more preferably 150% or more, and still more preferably from the viewpoint of suppressing tearing and breaking in high-speed continuous processing. It is 200% or more, particularly preferably 300% or more. The upper limit of the breaking elongation is not particularly limited, but is substantially about 500% due to the characteristics of the composition and the stretched film.

  The method for setting the elongation at break in direction b to 100% or more is not particularly limited as long as the effect of the present invention is not impaired, but, for example, the stretching temperature in the direction orthogonal to the direction having the highest stretching ratio and the same plane, A method for controlling the magnification is mentioned. The breaking elongation in the direction b can be increased by lowering the stretching temperature or by decreasing the stretching ratio in the direction a.

The biodegradable white film of the present invention preferably has a basis weight of 10 g / m ² or more and 50 g / m ² or less. The basis weight is more preferably 15 g / m ² or more and 40 g / m ² or less, and still more preferably 15 g / m ² or more and 30 g / m ² or less. By setting the basis weight to 10 g / m ² or more, a film having excellent film forming stability can be obtained, and by setting the basis weight to 50 g / m ² or less, a film having excellent biodegradability can be obtained.

The biodegradable white film of the present invention preferably has a moisture permeability of 400 g / (m ² · day) or more. By setting the moisture permeability to 400 g / (m ² · day) or more, problems such as insufficient moisture permeability and the occurrence of condensation on the high humidity side of the film can be suppressed. The moisture permeability is more preferably 500 g / (m ² · day) or more, and still more preferably 600 g / (m ² · day) or more. The upper limit of moisture permeability is not particularly limited, but is 10,000 g / (m ² · day) or less from the characteristics of the resin used and the uniaxially stretched product.

The method for setting the moisture permeability to 400 g / (m ² · day) or more is not particularly limited, but the filler B should have the above-described preferable content, and the biodegradable resin A can be a polylactic acid resin and biodegradable. The resin a is contained, the type and content thereof are preferably set as described above, the temperature in the heat treatment step is set in a preferable range in the manufacturing method described later, and the magnification in the stretching step is set in a preferable range. Can be mentioned. More preferred is a method of combining a plurality of these methods, and still more preferred is a method of combining all of these methods.

  The biodegradable white film of the present invention preferably has a film thickness of 5 μm or more and 50 μm or less. By setting the film thickness to 5 μm or more, the firmness of the film becomes strong and not only excellent in shape retention but also easy to handle, and roll roll shape and unwinding property are improved. By setting the film thickness to 50 μm or less, the film is excellent in flexibility and decomposability. The film thickness is more preferably 7 μm or more and 45 μm or less, and further preferably 10 μm or more and 40 μm.

  The biodegradable white film of the present invention preferably has a surface free energy of at least one side surface of 70 mN / m or less. By setting the surface free energy of at least one surface to 70 mN / m or less, it becomes possible to improve the adhesion when bonding with other materials. The surface free energy is more preferably 60 mN / m or less, and still more preferably 50 mN / m or less. The surface free energy is preferably as small as possible, and the lower limit is not particularly limited. However, from the viewpoint of improving the adhesion, about 25 mN / m is sufficient.

  The method of setting the surface free energy to 70 mN / m or less is not particularly limited as long as the effects of the present invention are not impaired. For example, a method of adding a thermoplastic elastomer C other than the biodegradable resin A as described above can be mentioned. .

  When the biodegradable white film of the present invention has a laminated structure of layer 1 and layer 2, the ratio T1 / T2 of the thickness T1 of layer 1 to the thickness T2 of layer 2 is preferably 1 or more and 20 or less, more preferably 2 or more and 10 Hereinafter, it is particularly preferably 4 or more and 8 or less. Here, when there are a plurality of layers 1 and 2, the total thickness of each layer is T1 and T2, respectively. By setting T1 / T2 to 1 or more and 20 or less or the above preferable range, it becomes possible to impart adhesion to the film while maintaining a high degree of biomass.

  When the biodegradable white film of the present invention has a laminated structure of layer 1 and layer 2, the thickness of layer 2 located on the surface layer is preferably 1 μm or more and 30 μm or less. More preferably, they are 2 micrometers or more and 20 micrometers or less, More preferably, they are 5 micrometers or more and 15 micrometers or less. By setting the thickness of the layer 2 positioned on the surface layer to 1 μm or more and 30 μm or less or the above preferable range, it is possible to impart good adhesion to the film.

  Next, the method for producing the biodegradable white film of the present invention will be specifically described using an example in which a polylactic acid resin is used as the biodegradable resin A. However, the present invention is not limited by this. Absent.

  The method for producing a biodegradable white film of the present invention includes a melt-kneading step of obtaining a resin composition by melt-kneading the biodegradable resin A and the filler B, and melting the resin composition from a die. A biodegradable white film having in this order a melt extrusion process for discharging to obtain an unstretched film, a stretching process for stretching the unstretched film in at least one direction to obtain a stretched film, and a heat treatment process for heating the stretched film. In the stretching step, when the melting point of the biodegradable resin A is Tm (° C.), the range of Tm-160 (° C.) to Tm-95 (° C.) is 1.5. Stretched by not less than 2 times and not more than 4 times.

  L-lactic acid or D-lactic acid is essential as a raw material for the polylactic acid resin that is one of the biodegradable resins A, and is a cyclic ester intermediate of a hydroxycarboxylic acid other than lactic acid, hydroxycarboxylic acid such as lactide or glycolide. Body, dicarboxylic acids, glycols and the like may be added.

  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. A polylactic acid-based resin can also be obtained by a method of ring-opening polymerization of a cyclic ester intermediate such as lactide using a catalyst such as tin octylate.

  Since the production method of the biodegradable white film of the present invention has few steps and high productivity, a melt-kneading step of obtaining a resin composition by melt-kneading biodegradable resin A and filler B is performed. Have.

  The mixer used in the melt-kneading process is not particularly limited as long as the effects of the present invention are not impaired, and a commonly used known mixer such as a kneader, roll mill, Banbury mixer, single-screw or twin-screw extruder is used. Can do. Among these, from the viewpoint of productivity, it is preferable to use a single screw or twin screw extruder.

  The temperature in the melt-kneading step depends on the type of the biodegradable resin A. For example, when a polylactic acid resin is used as the biodegradable resin, 150 ° C. or higher and 240 ° C. from the viewpoint of preventing the deterioration of the polylactic acid resin. The following range is preferable, and the range of 180 ° C. or higher and 220 ° C. or lower is more preferable.

  In the method for producing a biodegradable white film of the present invention, for example, the resin composition containing the biodegradable resin A and the filler B obtained by the melt-kneading step may be once pelletized and melt-kneaded again. At this time, from the viewpoint of suppressing hydrolysis during melt-kneading, the amount of water in the pellet is preferably 500 ppm or less, more preferably 200 ppm or less on a mass basis. Examples of the method of setting the moisture content in the pellet to 500 ppm or less on the basis of mass include a method of drying the pellet under suitable conditions. Suitable conditions when the biodegradable resin A is a polylactic acid resin are a temperature of 60 ° C. or higher and 100 ° C. or lower and a drying time of 6 hours or longer. In addition, when the biodegradable resin A is a polylactic acid-based resin, a method of vacuum drying under a high vacuum with a degree of vacuum of 10 Torr or less is preferable from the viewpoint of reducing the amount of lactic acid oligomer in the pellet.

  The method for producing a biodegradable white film of the present invention includes a melt extrusion process in which the resin composition obtained in the melt-kneading process is melted and discharged from a die to obtain an unstretched film.

  The die in the melt extrusion step is not particularly limited as long as the effect of the present invention is not impaired, and an appropriate one may be selected according to the film forming method to be employed. The production method of the biodegradable white film of the present invention is preferably an inflation method from the viewpoint of stretchability and production cost. When employing the inflation method, it is preferable to use an annular die for the die.

  In the method for producing a biodegradable white film of the present invention, when the inflation method is adopted, the resin composition obtained by the melt-kneading step is melt-extruded by an extruder, led to an annular die, and extruded from the annular die. Then, dry air is supplied from the center of the annular die to form bubbles, and air-cooled and solidified uniformly with an air ring. After being folded flat with a nip roll and taken up at a predetermined speed, both ends or one side as required Open the end of the wire and wind it up.

  At this time, the blow ratio of the bubble is preferably 1.3 or more and 3.5 or less from the viewpoint of the decomposability of the film, the width, and the stability of the bubble. By setting the bubble blow ratio to 1.3 or more, stable bubbles can be formed, and a film can be obtained with a good width. On the other hand, when the bubble blow ratio is 3.5 or less, a film having good decomposability can be obtained. Moreover, the draw ratio of the bubble is preferably 15 or more and 50 or less from the viewpoint of the decomposability and shape retention of the film.

  The method for producing a biodegradable white film of the present invention includes a stretching process in which an unstretched film obtained by a melt extrusion process is stretched in at least one direction to obtain a stretched film. Here, stretching in at least one direction means stretching in one direction or a plurality of directions.

  In the method for producing a biodegradable white film of the present invention, the unstretched film may be stretched only in one direction or in two orthogonal directions, but in a small number of steps, Ea / Eb and direction b Since the elongation at break can be in a desired range, it is preferable to stretch the unstretched film only in one direction.

  The method of setting Ea / Eb, which is the ratio of Young's modulus, to 1.2 or more and 2.5 or less is not particularly limited, but a method of stretching in at least one direction is preferably used, and a method of stretching in only one direction is particularly preferred. More preferably (hereinafter, the direction stretched at the highest magnification is referred to as the stretching direction, and the direction orthogonal to the stretching direction in the same plane is referred to as the orthogonal direction).

  By stretching the unstretched film produced by discharging from the aforementioned die in one direction, the Young's modulus (GPa) in the stretching direction can be increased, and the stretching direction becomes the direction a in which the Young's modulus is the largest. As a result, Ea / Eb can be set to 1.2 or more.

  Examples of the method for stretching the unstretched film include roll stretching using a difference in peripheral speed of the roll, and tenter stretching in which both ends in the width direction are gripped with a clip and run on a rail along a stretched pattern. In the method for producing a biodegradable white film of the present invention, any method can be used for stretching the film in one direction, but roll stretching is used from the viewpoint of productivity and simplicity of the apparatus configuration. preferable. The width direction refers to a direction that is parallel to the film transport surface and orthogonal to the direction in which the film travels during film production (sometimes referred to as the longitudinal direction).

  When roll-stretching an unstretched film, normally, after heating up an unstretched film to the temperature which stretches with a heating roll, it extends | stretches in a longitudinal direction with several stretching rolls from which a circumferential speed difference differs. An auxiliary heating means such as an infrared heater can be used in combination for raising the temperature. The stretching may be performed in one stage using two rolls having different circumferential speed differences, or may be performed in multiple stages using three or more rolls having different circumferential speed differences.

  In the stretching step of the method for producing a biodegradable white film of the present invention, from the viewpoint of film-forming stability, when the melting point of the biodegradable resin A is Tm (° C.), Tm-160 (° C.) or more and Tm— Stretching within a range of 95 (° C.) or less. Furthermore, in consideration of improving moisture permeability, concealability, and mechanical properties, it is preferable to stretch in the range of Tm-130 (° C.) to Tm-80 (° C.), and Tm-100 (° C.) to Tm. It is particularly preferable to stretch in the range of −75 (° C.) or less.

  Here, the melting point Tm (° C.) of the biodegradable resin A means that the biodegradable resin A is heated in a hot air oven at 100 ° C. for 24 hours, and then heated at a rate of temperature increase of 20 ° C./RDC220. The peak temperature of the crystal melting peak when the temperature is raised from 25 ° C. to 250 ° C. in minutes. In addition, since a plurality of components are contained in the biodegradable resin A, when a plurality of crystal melting peaks are confirmed, the temperature of the peak having the highest temperature is set as the melting point Tm (° C.) of the biodegradable resin A.

  Moreover, extending | stretching in the range of Tm-160 (degreeC) or more and Tm-95 (degreeC) is extending | stretching as extending | stretching roll temperature as the range of Tm-160 (degreeC) or more and Tm-95 (degreeC), A detailed method for measuring the drawing roll temperature will be described later.

  In the stretching process of the method for producing a biodegradable white film of the present invention, the heated unstretched film is stretched 1.5 times or more and 4 times or less from the viewpoint of setting the breaking elongation in the direction b to an appropriate range. And it is preferable to stretch 1.5 times or more and 2.5 times or less. If the draw ratio is higher than 4, the breaking elongation in the direction b may be reduced more than necessary. In addition, when extending | stretching in multiple steps, a draw ratio means the product of the draw ratio of each step.

  In the stretching process of the production method of the biodegradable white film of the present invention, it is preferable to stretch the unstretched film only in one direction, but if the stretching ratio in one direction is 1.5 times or more and 4 times or less, You may extend | stretch in two directions as needed.

  When the unstretched film is stretched in two directions, the stretch ratio in the direction where the stretch ratio is not 1.5 times or more and 4 times or less is a viewpoint that makes the film exhibit anisotropy of Young's modulus and film formation stability. Therefore, it is preferable to be greater than 1.0 times and less than 1.5 times.

  It is important for the manufacturing method of the biodegradable white film of this invention to have the heat processing process which heats a stretched film. Dimensional stability can be imparted to the stretched film by heat-treating the stretched film under tension in which the length in the stretched direction is fixed or while relaxing in the stretched direction. A preferable heat treatment temperature in this heat treatment step depends on the type of the biodegradable resin A, but is 50 ° C. or higher and 110 ° C. or lower when the biodegradable resin A is a polylactic acid resin.

  Although the heat treatment conditions in the method for producing a biodegradable white film of the present invention depend on the type of biodegradable resin A, when the biodegradable resin A is a polylactic acid resin, dimensional stability is imparted to the film. From the viewpoint, the heat treatment temperature is preferably 50 ° C. or higher and 110 ° C. or lower, and the heat treatment time is preferably 0.2 seconds or longer and 30 seconds or shorter. Moreover, when heat-treating while relaxing in the stretched direction, the relaxation rate is preferably 1% or more and 10% or less, preferably 3% or more and 5% or less, from the viewpoint of imparting dimensional stability to the film. More preferred.

  The biodegradable white film of the present invention is suitable for applications requiring concealability, flexibility, moisture permeability, mechanical properties, and processability, and for applications requiring shape retention and biodegradability. Is also suitable. Specifically, agricultural materials such as various labels, cards, labels, adhesive tapes, and multi-films, forestry materials such as fumigation sheets, bed sheets, pillow covers, sanitary materials such as sanitary napkins and paper diapers, and for rainy weather It can be preferably used for clothing materials such as clothing and gloves, garbage bags and compost bags, food bags such as vegetables and fruits, and various packaging materials for industrial products.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited thereto.

[Measurement and evaluation method]
Measurements and evaluations shown in the examples were performed under the following conditions.

(1) Filler content of film (Wb1, Wb2)
A solution obtained by dissolving 1.0 g of a film in 100 ml of tetrahydrofuran at 25 ° C. is centrifuged for 30 minutes at 5 ° C. and 10000 rpm in a centrifuge (manufactured by Kubota Corporation, product name: high-speed cooling centrifuge, model number: 6000). The insoluble components were extracted and collected. After drying insoluble components on a hot plate heated to 50 ° C., 0.1 g is weighed, and sulfuric acid, nitric acid, and perchloric acid are sequentially added thereto to thermally decompose the insoluble components to remove organic substances. The solution was concentrated until white smoke was produced. Hydrofluoric acid was added to the sample after concentration, and the mixture was further heated at 200 ° C. to dissolve inorganic substances, heated and dissolved with dilute nitric acid, and allowed to cool. The sample after standing to cool was diluted to 20 ml with dilute nitric acid. After diluting the obtained solution, Ca and Ti are quantified by performing ICP emission spectroscopic analysis under the following measurement conditions using a sequential type ICP emission spectroscopic analyzer SPS4000 manufactured by SII / Nanotechnology. The molar ratio of was determined.
<Measurement conditions>
Measurement wavelength Ca: 393.37 nm, Ti: 334.941 nm
High frequency output 1.3kW
Plasma gas flow rate 16L / min
Auxiliary gas flow rate 0.5L / min
Carrier gas flow rate 1.0L / min
Metering height 15mm

Using the molar ratio of Ca and Ti obtained by ICP emission spectroscopic analysis, the amount of calcium carbonate (Wb1) and the amount of titanium oxide (Wb2) were determined from the following formulas (a) and (b).
Formula (a) Calcium carbonate amount (Wb1) = Ca amount (molar ratio) × 100/40
Formula (b) Titanium oxide amount (Wb2) = Ti amount (molar ratio) × 80/48
(Calculated as Ca = 40 g / mol, CaCO ₃ = 100 g / mol, Ti = 48 g / mol, TiO ₂ = 80 g / mol)

Wb1 + Wb2 and Wb1 / Wb2 were calculated from Wb1 and Wb2 obtained by the equations (a) and (b).
The method described here is for the case where the filler b1 is calcium carbonate and the filler b2 is titanium oxide. When other fillers are used, the target and calculation formula to be quantified by ICP emission spectroscopic analysis are different. . Moreover, about the example (Comparative Example 1 mentioned later) which does not contain a filler, Wb1 + Wb2 shall be 0 mass part and Wb1 / Wb2 cannot be calculated.

(2) Mechanical properties of the film (Young's modulus Ea in direction a, Young's modulus Eb in direction b, elongation at break in direction b)
First, a rectangular sample having a length of 150 mm and a width of 10 mm was cut out arbitrarily from the film surface. Next, samples of the same size and shape were cut out from the film surface so that the angle formed by the length direction and the length direction of the sample cut out immediately before was 10 °. This was repeated until the number of samples reached 19, that is, until the angle formed by the length direction of the first sample and the length direction of the last sample reached 180 degrees. The Young's modulus of the sample thus obtained was measured at 23 ° C., relative humidity 65%, initial tensile chuck distance 50 mm, and tensile speed 200 mm / min using “TENSILON” (registered trademark) UCT-100 manufactured by Orientec. , And measured according to the method defined in JIS K-7127 (1999 edition). This measurement was performed 5 times, and the direction in which the average value of Young's modulus was the largest was defined as direction a, and the direction perpendicular to the same plane was defined as direction b.
Then, a rectangular sample having a length of 150 mm and a width of 10 mm with the determined direction a and direction b as the length direction is cut out from the film surface, and the Young's modulus in each direction and the breaking elongation in direction b are manufactured by Orientec. Measured using a TENSILON (registered trademark) UCT-100 at a room temperature of 23 ° C., a relative humidity of 65%, a distance between initial tensile chucks of 50 mm, and a tensile speed of 200 mm / min, according to the method defined in JIS K-7127 (1999 edition) did. The measurement was carried out 10 times in each direction, and the average value of each measurement value obtained was determined by using the Young's modulus in the direction a (Ea GPa), the Young's modulus in the direction b (Eb GPa), and the breaking elongation in the direction b. (%). Furthermore, Ea / Eb was calculated from the Young's modulus in the direction a and the direction b measured by the above method. The values of Ea, Eb, and Ea / Eb were calculated as values up to the first decimal place by rounding off the second decimal place. The breaking elongation in the direction b was a value rounded off to one decimal place.

(3) Flexibility of film Using the value of Young's modulus Ea obtained by the method described in (2) as an index of flexibility, the flexibility of the film was evaluated according to the following criteria. In addition, A has the most excellent flexibility of the film.
A: 1.5 GPa or less B: Greater than 1.5 GPa, 2 GPa or less C: Greater than 2 GPa

(4) Moisture permeability of film The moisture permeability (g / (m ² · day)) was measured by a constant temperature and humidity apparatus set at 25 ° C. and 90% RH according to the method defined in JIS Z0208 (1976). This measurement was performed three times, and the average value of the obtained values was regarded as the moisture permeability of the film and evaluated according to the following criteria. In addition, A is the most excellent in the water vapor transmission rate of the film.
^{A: 600g / (m 2 ·} day) or more ^{B: 500g / (m 2 ·} day) or ^{more, 600g / (m 2 · day} ) under ^{C: 400g / (m 2 ·} day) or more, 500g / ^{(m 2} · less than day) D: less than 400 g / (m ² · day)

(5) Melting point (Tm) of biodegradable resin A
The biodegradable resin A described later was individually heated in a hot air oven at 100 ° C. for 24 hours, and then, using a differential scanning calorimeter RDC220 manufactured by Seiko Instruments Inc., 5 mg of a sample was set on an aluminum pan, and from 25 ° C. The peak temperature of the crystal melting peak when the temperature was raised to 250 ° C. at a rate of temperature rise of 20 ° C./min was defined as the melting point Tm (° C.) of the biodegradable resin A. In addition, since a plurality of components are contained in the biodegradable resin A, when a plurality of crystal melting peaks are confirmed, the temperature of the peak having the highest temperature is defined as the melting point Tm (° C.) of the biodegradable resin A. Moreover, when the composition was obtained in the form of a film or the like, measurement was similarly performed using the film, and the peak temperature of the obtained crystal melting peak was defined as the melting point Tm (° C.) of the film.

(6) Haze of film (whiteness)
According to JIS-K7136 (2000), the haze was measured using the Nippon Denshoku Industries Co., Ltd. haze meter NDH2000. The average value obtained was evaluated as the haze of the film according to the following criteria. Note that A is the most excellent haze of the film.
A: 80% or more B: 70% or more, less than 80% C: less than 70%

(7) Total light transmittance of film (concealment)
The total light transmittance was measured three times by the same method as in (6). The average value of the obtained values was evaluated as the total light transmittance of the film according to the following criteria. In addition, A is the most excellent in the total light transmittance of a film.
A: 60% or less B: Greater than 60%, 70% or less C: Greater than 70%

(8) Reflectivity of the film The basic configuration using the integrating sphere attached to the spectrophotometer U-4100 (manufactured by Hitachi, Ltd.), with a wavelength of 400 nm to 800 nm based on the sub-white plate of aluminum oxide attached to the apparatus. The reflectance of the film under the conditions was measured. The reflectance was measured three times for each side of the film, the average value of the reflectance on each surface was determined, and the higher value was taken as the reflectance of the film. Using that value, practical evaluation was performed according to the following criteria. In addition, a larger value of reflectance is preferable.
A: 40% or more B: 30% or more, less than 40% C: less than 30%

(9) Stretching roll temperature The stretching roll temperature was measured with DIGITAL THERMOMETER (TX10) manufactured by Yokogawa Meter & Instruments. The measurement was performed at the center of the roll with the roll stopped.

(10) Surface free energy Measurement was performed according to the following procedures I) to VIII).
I) In order to distinguish the front and back of the film, one of the film surfaces was designated as the A surface, and the other surface was designated as the B surface. First, the contact angle of the measurement liquid on the film surface was measured using the contact angle CA-D type (manufactured by Kyowa Interface Science Co., Ltd.) at 23 ° C. and 65% RH on the A surface. The measurement was performed five times on one measurement surface, and the arithmetic average value was defined as the contact angle θ (°).
II) Next, the contact angle θ (°) of ethylene glycol on the film surface was determined under the same conditions and method as in I) except that ethylene glycol was used as the measurement liquid.
III) Next, the contact angle θ (°) of methylene iodide on the film surface was determined under the same conditions and method as in I) except that methylene iodide was used as the measurement solution.
IV) The following formula was established for each measurement solution.
(ΓSd · γLd) ^1/2 + (γSp · γLp) ^1/2 + (γSh · γLh) ^1/2 = (1 + cos θ) / 2
Here, γLd is the dispersion force of the measurement liquid, γLp is the polar force of the measurement liquid, and γLh is the hydrogen bonding force of the measurement liquid. When the measurement liquid is water, γLd = 10.8 mN / m, γLp = 22.74 mN / m, and γLh = 38.46 mN / m. When the measurement liquid is ethylene glycol, γLd = 17.5 mN / m. ΓLp = 4.69 mN / m, γLh = 25.96 mN / m, and when the measurement solution is methylene iodide, γLd = 43.7 mN / m, γLp = 1.31 mN / m, γLh = 2.65 mN. / M. Further, θ represents the contact angle of the measurement liquid on the measurement surface.
V) A ternary simultaneous equation obtained by substituting γLd, γLp, γLh, and θ into the above equation was solved for γSd, γSp, and γSh.
VI) The sum of γSd, γSp, and γSh was defined as the surface free energy (mN / m) of the measurement surface.
VII) The surface B energy of the film was also measured in the same procedure as in I) to VI), and the surface free energy was calculated.
Of the surface free energy on the surface of the film A obtained in VIII) VI) and the surface free energy on the surface of the film B obtained in VII), a lower value was adopted as the surface free energy of the film.

(11) Peel strength Two pieces of film having a width of 20 mm × 15 cm are bonded with a double-sided tape (“Nystack” (registered trademark) 20MMX10M NW-20, manufactured by Nichiban Co., Ltd.), and the peel strength is JIS K 6854-3 It was measured according to the method described in (1999 edition). The measurement was performed three times, and the average value of the obtained measurement values was defined as the peel strength (MPa), and evaluated according to the following criteria.
When peel strength is 8 MPa or more: A
When peel strength is 5 MPa or more and less than 8 MPa: B
When peel strength is less than 5 MPa: C

[Biodegradable resin A]
<Polylactic acid resin>
(A-1)
Crystalline polylactic acid resin, mass-average molecular weight = 200,000, D-form content = 1.4 mol%, melting point = 166 ° C., biodegradability = 99% (40 days, JIS K6955-2 (2010))
(A-2)
Amorphous polylactic acid resin, mass average molecular weight = 200,000, D-form content = 12.0 mol%, melting point = none, biodegradability = 99% (40 days, JIS K6953-2 (2010))
In addition, said mass mean molecular weight was measured using Japan Waters Co., Ltd. product Waters2690, polystyrene as a standard, column temperature of 40 degreeC, and the chloroform solvent. Moreover, said melting | fusing point was calculated | required according to the method as described in (4).
<Biodegradable resin other than polylactic acid resin (biodegradable resin a)>
(A-1)
Polybutylene succinate resin (trade name “GSPla” (registered trademark) AZ91T, manufactured by Mitsubishi Chemical Corporation), biodegradability = 85% (40 days, JIS K6953-2 (2010))
(A-2)
62 parts by mass of polyethylene glycol having a number average molecular weight of 8,000, 38 parts by mass of L-lactide and 0.05 parts by mass of tin octylate are mixed and polymerized in a reaction vessel equipped with a stirrer at 160 ° C. for 3 hours in a nitrogen atmosphere. Thus, a block copolymer having polylactic acid segments having a number average molecular weight of 2,500 at both ends of polyethylene glycol having a number average molecular weight of 8,000 was obtained. Biodegradation = 80% (300 days, JIS K6953-2 (2010 edition))

[Filler (B)]
(B1)
Calcium carbonate (Ajinomoto Fine Techno Co., Ltd., trade name “Top Flow” H200, average particle size: 1.7 μm, surface treatment agent: phosphate compound)
(B2)
Rutile-type titanium oxide particles with an average particle size of 200 nm

[Thermoplastic elastomer C other than biodegradable resin A]
(C-1)
Acrylic thermoplastic elastomer, trade name “Clarity” (registered trademark) LA2140

(Examples 1-18, Comparative Examples 1-4)
As biodegradable resin A, crystalline polylactic acid resin (A-1) 7.5 mass%, amorphous polylactic acid resin (A-2) 22.5 mass%, polybutylene succinate resin (a- 1) 40% by mass, using 30% by mass of a block copolymer (a-2) having a polyether-based segment and a polylactic acid-based segment, with respect to 100 parts by mass of the biodegradable resin A, calcium carbonate (b1) A mixture of the contents (Wb1, Wb2) of titanium oxide (b2) shown in Table 1 or 2 was supplied to a twin screw extruder with a vacuum diameter of 44 mm and a cylinder temperature of 190 ° C., and the vacuum vent part was deaerated. After melt-kneading, homogenizing, and pelletizing, a composition was obtained. The results of evaluating the melting point Tm of this composition are shown in Table 1 or 2.

The pellets of the composition obtained above were supplied to a twin screw extruder with a vacuum vent with a cylinder temperature of 180 ° C., and the blow ratio was 2.1 from a spiral annular die having a diameter of 50 mm, a lip clearance of 1 mm, and a temperature of 160 ° C. Then, it is extruded upward in a bubble shape, cooled by air with a cooling ring, taken up while being folded with a nip roll above the die, cut at both ends with an edge cutter, cut into two pieces, each wound with a winder, and a final thickness of 40 μm A film was obtained.
This unstretched film is led to a roll-type stretching machine, stretched at a temperature shown in Table 1 or 2 in the longitudinal direction at a temperature of 50 ° C., and once cooled on a cooling roll, heat-treated through a roll at a temperature of 50 ° C., A film was obtained. The physical properties of the obtained film are shown in Table 1 or 2.

(Examples 19 to 30)
As biodegradable resin A, crystalline polylactic acid resin (A-1) 7.5 mass%, amorphous polylactic acid resin (A-2) 22.5 mass%, polybutylene succinate resin (a- 1) 40% by mass, using 30% by mass of a block copolymer (a-2) having a polyether-based segment and a polylactic acid-based segment, with respect to 100 parts by mass of the biodegradable resin A, calcium carbonate (b1) In the same manner as in Example 1, except that the titanium oxide (b2) was used in the contents (Wb1, Wb2) shown in Table 3 and the thermoplastic elastomer (C) was used in a mixture containing the contents shown in Table 3. A film was obtained. Table 3 shows the physical properties of the obtained film.

(Examples 31-39)
As composition of layer 1, as biodegradable resin A, crystalline polylactic acid resin (A-1) 7.5% by mass, amorphous polylactic acid resin (A-2) 22.5% by mass, poly Butylene succinate resin (a-1) 40% by mass, block copolymer (a-2) 30% by mass having a polyether segment and a polylactic acid segment, and 100 parts by mass of the biodegradable resin A Then, a mixture having the contents (Wb1, Wb2) shown in Table 4 for calcium carbonate (b1) and titanium oxide (b2) was used. Further, as the composition of layer 2, as biodegradable resin A, 7.5% by mass of crystalline polylactic acid resin (A-1), 22.5% by mass of amorphous polylactic acid resin (A-2), Using 40% by mass of polybutylene succinate resin (a-1) and 30% by mass of a block copolymer (a-2) having a polyether segment and a polylactic acid segment, 100 parts by mass of the biodegradable resin A On the other hand, the contents of calcium carbonate (b1) and titanium oxide (b2) are the contents (Wb1, Wb2) shown in Table 4, and the thermoplastic elastomer (C) is the mixture of contents shown in Table 4 as in Example 1. Pelletized in the same manner. The results of evaluating the melting point Tm (° C.) of these compositions are shown in Table 4. The pellets of the composition obtained above were supplied to a twin-screw extruder with a vacuum vent with a cylinder temperature of 180 ° C. in an inflation machine having two extruders, and each had a diameter of 50 mm, a lip clearance of 1 mm, and a temperature of 160 ° C. Merged in a spiral annular die, merged to form layer 2 / layer 1 / layer 2, extruded upward in a bubble shape with a blow ratio of 2.1, air cooled with a cooling ring, and folded with a nip roll above the die Then, both ends were cut with an edge cutter and cut into two pieces, and each was wound with a winder to obtain a film having a final thickness of 40 μm.
This unstretched film was stretched at the magnification shown in Table 4 in the same manner as in Example 1, and once cooled on a cooling roll, it was heat-treated through a roll at a temperature of 50 ° C. to obtain a film. Table 4 shows the physical properties of the obtained film.

  Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on a Japanese patent application filed on March 27, 2015 (Japanese Patent Application No. 2015-066001) and a Japanese patent application filed on March 27, 2015 (Japanese Patent Application No. 2015-066002). Incorporated herein by reference.

  According to the present invention, a biodegradable white film excellent in flexibility, moisture permeability, mechanical properties, and processability is provided. The film of the present invention can be preferably used for applications mainly requiring flexibility, moisture permeability and mechanical properties. Specifically, agricultural materials such as various labels, cards, labels, adhesive tapes, multi-films, forestry materials such as fumigation sheets, bed sheets, pillow covers, sanitary materials such as sanitary napkins and paper diapers, clothing, It can be preferably used for clothing materials such as gloves, garbage bags and compost bags, food bags such as vegetables and fruits, and various packaging materials for industrial products.

Claims (14)

A biodegradable white film containing biodegradable resin A and filler B,
The filler B contains a filler b1 which is a filler having a void forming ability and a filler b2 which is a high refractive index filler, the content of the filler b1 is Wb1, and the content of the filler b2 A biodegradable white film in which Wb1 + Wb2 is 3 to 25 parts by mass and Wb1 / Wb2 is 2 to 20 with respect to 100 parts by mass of the biodegradable resin A when the amount is Wb2.   The biodegradable white according to claim 1, wherein the filler b1 is at least one of calcium carbonate and barium sulfate, and the filler b2 is at least one of titanium oxide and zinc oxide. the film.   When the Young's modulus (GPa) in the direction with the largest Young's modulus (direction a) is Ea, and the Young's modulus in the direction (direction b) perpendicular to the same plane as the direction a is Eb, Ea / Eb is 1.2. The biodegradable white film according to claim 1 or 2, wherein the biodegradable white film has a breaking elongation in the direction b of 100% to 500%.   The biodegradable white film according to any one of claims 1 to 3, wherein the biodegradable resin A includes a polylactic acid resin. The biodegradable resin A includes a polylactic acid resin and a biodegradable resin other than the polylactic acid resin,
When the biodegradable resin A is 100% by mass, the content of the polylactic acid resin is 10% by mass to 95% by mass, and the content of the biodegradable resin other than the polylactic acid resin is The biodegradable white film according to any one of claims 1 to 4, which is 5% by mass or more and 90% by mass or less.   A biodegradable resin other than the polylactic acid resin is a block copolymer having a polyether segment and a polylactic acid segment, a block copolymer having a polyester segment and a polylactic acid segment, an aliphatic polyester resin, The biodegradable white film according to claim 5, which is at least one resin selected from the group consisting of an aliphatic aromatic polyester-based resin.   The Young's modulus Ea in the direction with the largest Young's modulus (direction a) is 1.5 GPa or less, and the surface free energy of at least one surface is 70 mN / m or less. Biodegradable white film. A biodegradable white film containing biodegradable resin A and filler B,
When the Young's modulus (GPa) in the direction where the Young's modulus is the largest (direction a) is Ea, and the Young's modulus in the direction orthogonal to the direction a (direction b) is Eb, Ea is 2 GPa or less, A biodegradable white film having Ea / Eb of 1.2 or more and 2.5 or less and a breaking elongation in direction b of 100% or more.   The biodegradable white film according to claim 8, wherein the biodegradable resin A includes a polylactic acid resin. The biodegradable resin A includes a polylactic acid resin and a biodegradable resin other than the polylactic acid resin,
When the biodegradable resin A is 100% by mass, the content of the polylactic acid resin is 10% by mass to 95% by mass, and the content of the biodegradable resin other than the polylactic acid resin is The biodegradable white film of Claim 8 or 9 which is 5 mass% or more and 90 mass% or less.   A biodegradable resin other than the polylactic acid resin is a block copolymer having a polyether segment and a polylactic acid segment, a block copolymer having a polyester segment and a polylactic acid segment, an aliphatic polyester resin, The biodegradable white film according to claim 10, which is at least one resin selected from the group consisting of an aliphatic aromatic polyester-based resin.   The biodegradable white film according to any one of claims 8 to 11, comprising 1 to 50 parts by mass of the filler B with respect to 100 parts by mass of the biodegradable resin A.   The biodegradable white film according to any one of claims 8 to 12, wherein the surface free energy of at least one side surface is 70 mN / m or less. A melt-kneading step of obtaining a resin composition by melt-kneading the biodegradable resin A and the filler B;
A melt extrusion process in which the resin composition is melted and discharged from a die to obtain an unstretched film,
A stretching step of stretching the unstretched film in at least one direction to obtain a stretched film,
And it is a manufacturing method of the biodegradable white film according to any one of claims 1 to 13 which has the heat treatment process which heats the stretched film in this order,
In the stretching step, when the melting point of the biodegradable resin A is Tm (° C.), the stretching is 1.5 times or more and 4 times or less in the range of Tm-160 (° C.) to Tm-95 (° C.). A method for producing a biodegradable white film.