CN106147163A - Micro-porous polylactic acid orientation film - Google Patents

Abstract

The invention provides a kind of micro-porous polylactic acid orientation film, there is surface holes in the range of 10-1000nm for the diameter, the circularity of this pores is less than 1.2, such hole area sum accounts for more than the 20% of described film total surface area, this film also has internal holes in the range of 10-1000nm for the diameter simultaneously, and the sphericity of such internal holes is more than 0.8.It is an advantage of the current invention that to prepare nanometer level microporous micro-porous oriented film with uniform spherical hole, this film has isotropism, and processing method is simply, at a high speed, can part even complete biodegradable.This micro-porous oriented film can be applied in the field such as hygiene care, medical treatment, building, water process, agricultural, electronic product, packaging, decoration.

Description

Micro-porous polylactic acid orientation film

Technical field

The invention belongs to polymeric material field, relate to a kind of polylactic acid film with microporous structure.

Background technology

Micro-porous membrane is as moisture permeable waterproof film, battery diaphragm, separation film, tissue engineering material, storage Energy materials etc. are many at hygiene care, medical treatment, building, water process, agricultural, electronic product, decoration etc. The field of kind is widely used.The preparation method of micro-porous membrane, mainly have foaming, particle-filled-stretching, Solvent etched, separated, self assembly etc., micro-porous membrane that various methods prepare structurally is respectively arranged with spy Point.

PLA is a kind of Biodegradable polyester, and the micro-porous membrane containing this polymer is referred, permissible The field such as hygiene care, medical treatment is applied.

CN 201310185870.6 uses the method for particle-filled-stretching, provides one raw containing PLA etc. Micro-porous oriented film of thing degradation polymer, the area of surface holes in 0.2～7 μ m for the diameter Accounting for the 0.5%-15% of total surface area, fastness to water is more than 800mm, and moisture permeability is more than 1000g/m²Day, Firm softness is less than 40mm.Health care field can be used for as moisture permeable waterproof film.

CN 201110414695.4 uses phase detachment technique, and a kind of aperture of offer can between 5-400 μm The poly-lactic acid material of control, can use as the porous support of used in tissue engineering.

CN 201080052568.8 uses size-reduced for the foaming body of PLA formation powder, described powder It is bonded with each other by melted adhesion, obtain the continuous poriferous construction between 100-2000 μm of aperture again, Can be used as absorbent material.

Empty structure deviation in most micro-porous membrane is spherical, and deviates spherical pore space structure meeting Cause the anisotropy of film, certain applications may result in the defect in some structural strengths.

The aperture of micro-porous membrane that above-mentioned each technology prepares is different, but be all difficult to prepare have nanometer, Submicron order is other, micro-porous polylactic acid film of uniform pore diameter and void shape subglobular.

Content of the invention

As the range of application of micro-porous membrane constantly expands, it has been found that in prior art, micro-porous is gathered The large scale aperture of lactic acid film, uneven pore-size distribution, void shape is irregular, mechanical property is each The defects such as anisotropy, limit it and produce at hygiene care, medical treatment, building, water process, agricultural, electronics The application of the multiple fields such as product, packaging, decoration.

In order to solve the defect of prior art, the present invention provides a kind of micro-porous polylactic acid orientation film.

So-called oriented film, is term known to those skilled in the art, refer to through curtain coating, blowing, Former film (unorientating film) prepared by the methods such as cast, mold pressing, through uniaxial or biaxial stretching, makes polymer Molecule segment, strand and/or crystallization are orientated, and prepare.The formation of orientation typically gives Film in beneficial performance and character, such as film strength, toughness, the raising of the transparency；Depending on post processing Condition, it is possible to make film have heat-shrinkable.The orientation of film can be on unidirectional, two-way stretching-machine Carry out, it is also possible to carried out by improved blow moiding methods such as double-membrane soaking methods (bubble tube method).Detection film is The method of no orientation is known technology, conventional have X-ray diffraction method, birefringence method, Raman spectroscopy, Infrared method, ultrasonic method etc..

The present invention provides a kind of micro-porous polylactic acid orientation film, and described oriented film has diameter and exists Surface holes in the range of 10-1000nm, the average circularity of described surface holes is less than 1.2.

Relative to non-oriented polylactic acid film, the polylactic acid film of orientation has more preferable intensity and storage Stability.The film less than 1.2 for the average circularity of surface holes, its surface holes trends towards circle, has The film of this kind of pore structure, its mechanical property etc. has isotropism.It is similar to, have and be close to round Hole, its draw ratio is close to 1, and film below 1.4 for the average aspect ratio belongs to the protection of the present invention Scope.

Heretofore described surface holes refers to be exposed to outside, and incomplete by polymer and/or other holes The hole covered, can be observed this pores on the membrane surface by microscope.

The aperture of nanoscale in the range of 10-1000nm for the diameter and submicron order is not hindering steam On the premise of infiltration, can effectively hinder passing through of liquid water.

Further, surface holes in the range of 10-1000nm for the diameter of the present invention, such surface The pore-size distribution in hole is less than 2.0, and the area sum of such surface holes accounts for described micro-porous polylactic acid orientation film More than the 20% of total surface area.

The area in described hole refers to, during film water placing flat, and hole projected area in the horizontal plane.Institute The film total surface area stated refers to, during film water placing flat, and film projected area in the horizontal plane.

Increase the hole area sum of surface holes in the range of 10-1000nm for the diameter, be conducive to improving moisture-inhibiting Degree.In the present invention, it is preferable that such hole area sum accounts for described micro-porous polylactic acid orientation film total surface Long-pending more than 20%.In view of increasing moisture permeability further, in the present invention, above-mentioned have diameter at 10-1000 The area sum of the surface holes in the range of nm more preferably account for the 35% of described film total surface area with On, still more preferably more than 45%.The upper limit of the area in aforementioned surfaces hole is not particularly limited, its example As can be below 70%.

Uniform pore diameter is conducive to improving mechanical performance, the uniformity of water vapour permeability of film.In the present invention, The above-mentioned uniform pore diameter with surface holes in the range of 10-1000nm for the diameter, pore-size distribution is preferably smaller than 2.0, more preferably less than 1.5, it is further preferably no larger than 1.3.The lower limit of pore-size distribution is not particularly limited, They for example can be more than 1.05.

Further, above-mentioned micro-porous polylactic acid film, surface in the range of 10-1000nm for its diameter In hole, the surface holes number less than 1.2 for the circularity accounts for more than the 80% of such surface holes sum.Have close The number in circular hole accounts for the ratio of more than 80% in such surface holes, has the film table of this kind of structure Face shape is consistent, it is ensured that the isotropism of its entirety.

Further, in above-mentioned micro-porous polylactic acid orientation film, also there is diameter at 10-1000nm In the range of internal holes, the sphericity of described internal holes be more than 0.8.The existence of internal holes is beneficial to into one Step improves the rate of perviousness of film.The bulbous configuration of internal holes makes film integrally present isotropism.

Heretofore described internal holes refers to the hole completely by polymer and/or other maskaperture masks, Ke Yitong Cross microscope on the cross section of film, observe this pores.

The pore-size distribution of internal holes in the range of 10-1000nm for the described diameter is less than 2.0, in such The area of section accounting in hole, portion is more than 20%.Uniform pore diameter is conducive to improving the mechanical performance, thoroughly of film The uniformity of wet performance.Described internal holes can be weighed the amount of this pores by area of section accounting.Profit By the means such as diamond cutter or ion polishing, along longitudinal direction (MD) or horizontal (TD) direction, the system of film After going out MD-normal direction (ZD) section or TD-ZD section, with microscope (electron microscope or atom Force microscope etc.) observe this section, recycle image processing techniques, this pores can be added up at film Area sum on MD-ZD section or TD-ZD section accounts for the percentage (area of section of this cross-sectional area Accounting).After statistical computation, being 100% with cross-sectional area, in the present invention, above-mentioned diameter is at 10-1000nm In the range of the area of section accounting of internal holes be preferably more than 20%.In view of raising moisture permeability further, In the present invention, internal holes in the range of 10-1000nm for the above-mentioned diameter further preferred more than 35%, then Further preferred more than 45%.The upper limit of the area of section accounting in aforementioned inner hole is not particularly limited, its For example can be below 70%.In view of the uniformity improving film, in the present invention, above-mentioned diameter exists The uniform pore diameter of the internal holes in the range of 10-1000nm, pore-size distribution is preferably smaller than 2.0, excellent further Choosing is less than 1.5, is still further preferably less than 1.3.The lower limit of aforementioned aperture distribution is not particularly limited, its For example can be more than 1.1.

The number of the internal holes with the sphericity more than 0.8 in the range of 10-1000nm for the described diameter Mesh accounts for more than 80%.The number in the hole with subglobular accounts for the ratio of more than 80%, has this kind of structure Film surface hole shape consistent, it is ensured that the isotropism of its entirety.

In view of the poisture-penetrability improving film further, in the present invention, above-mentioned micro-porous polylactic acid orientation is thin In film, can also have diameter and be more than 1 μm, and less than the internal holes in 100 μ m.Can be above Described in method add up.It after statistical computation, is 100% with cross-sectional area, above-mentioned in the present invention There is diameter and be more than 1 μm, be preferably 10% less than the area of section accounting of the internal holes in 100 μ m Above.The lower limit of above-mentioned area of section accounting is not particularly limited, and it can be for example less than 30%.

Described micro-porous polylactic acid orientation film, the component containing following parts by weight: polylactic resin A:40-99 weight portion, hydrophilic organic compound B:0.1-60 weight portion；Described hydrophily is organic Compound B is selected from water soluble or can one or more in organic compound swelling in water.

From structure, described polylactic resin A can be any polylactic resin, further, Can be that PLA (polylactide) or lactic acid are with one or more in the copolymer of other chemical constitutions.

The molecular structure of preferred PLA is, by the 80-100mol% of L lactic acid or D lactic acid and each Enantiomer 0-20mol% constitute molecular structure.Above-mentioned polylactic resin can be from L lactic acid or D breast One or both in Suan are as raw material, and obtained by dehydrating polycondensation.Preferably, can be from work For the lactide of the cyclic dimer of lactic acid, obtained by ring-opening polymerisation.Lactide has L lactic acid Cyclic dimer i.e. L lactide, the cyclic dimer i.e. D lactide of D lactic acid, D lactic acid and L lactic acid Carry out the racemic of Study of Meso-Lactide and D lactide and L lactide obtained from cyclic dimer Mixture i.e. DL lactide.The present invention can use any lactide.But, main material is excellent Select D lactide or L lactide.

Described lactic acid, with the copolymer of other chemical constitutions, refers to lactic acid with any chemical structural units shape One or more in the random copolymer, block copolymer or the graft copolymer that become.Wherein, lactic acid list There is no particular limitation for the chain length of unit, but examines from the angle of the mechanical property improving micro-porous membrane Considering, preferably lactic acid chain length is 1-20 ten thousand weight average molecular weight.Described lactic acid is with other chemical constitutions Copolymer, considers from the angle improving biological degradability and environment friendly, preferably lactic acid is with hydroxyl carboxylic Acids, binary or polyalcohols or the copolymer of binary or polybasic carboxylic acid class.

From crystal property, described polylactic resin A can be crystalline polylactic acid resin, it is possible to To be amorphism polylactic resin, can be or crystalline polylactic acid resin and amorphism polylactic resin Mixture.Consider from improving processability, preferably amorphism polylactic resin or crystalline polylactic acid Resin and the mixture of amorphism polylactic resin.Crystalline polylactic acid resin and amorphism are gathered The mixture of lactic acid resin, considers from improving processability, preferably amorphism polylactic resin accounts for mixing More than the 30% of thing gross weight, further preferred more than 50%.

Multiple method is had to can be determined that crystalline polylactic acid resin and amorphism polylactic resin in film Ratio.One of method is, by differential scanning calorimetric analysis (DSC).Carry out component to film sample to divide From, after isolating PLA component, carry out DSC test, by calculate melting enthalpy size can be determined that Crystalline polylactic acid resin and the ratio of amorphism polylactic resin.

With regard to the molecular weight of polylactic resin A, there is no particular limitation, but from improve molding processibility and Consider in the angle of mechanical property, preferable weight-average molecular weight 50,000～500,000, further preferred 80,000-30 ten thousand.

The above water-soluble organic compound refers to: when a certain temperature of 4-100 DEG C, This organic compound can dissolve more than 1g in 100g water.

Organic compound that can be swelling in water refers to: when a certain temperature of 4-100 DEG C, and this is organic for 1g There is the volumetric expansion of more than 10% in compound in 100g water.

Described hydrophilic organic compound B can be small molecular organic compounds, it is also possible to be big molecule Organic compound and/or polymer.

Specifically, described hydrophilic organic compound B can be selected from ethylene glycol, a contracting diethyl two The carboxylic acid micromoleculars such as alcohols micromolecular compound, succinic acid or lactic acid such as alcohol, glycerine or propane diols The esters such as compound, lactide, caprolactone, lactate, citrate, glyceride or Coronex Micromolecular compound, polyethylene glycol, polyethylene glycol oxide, polypropylene glycol, polyethylene glycol propane diols are altogether The polyether-based polymers such as polymers or polyethers-polyolefin copolymer, polyether-polyester copolymer, polyether-type gather Urethane, polyvinyl alcohol, ethylene imine, polyvinylpyrrolidone, polyacrylamide, poly, Diallyl quaternary ammonium polymer, poly-aspartate, poly-epoxy succinic acid, Carboxymethylinulin, starch or One or more in its derivative, cellulose ether, chitin, xanthans or natural plant gum.

From the ready availability consideration of raw material, described hydrophilic organic compound B be preferably ethylene glycol, glycerine, Succinic acid, lactic acid, lactide, lactate, ATBC, triethyl citrate, acetyl lemon Triethylenetetraminehexaacetic acid ester, tributyl 2-acetylcitrate, glyceryl triacetate, Coronex, polyethylene glycol, poly- Ethylene oxide, polypropylene glycol, polyethylene glycol propylene glycol copolymers, PLGA-PEG-PLGA, Polypropylene glycol-copolymer of poly lactic acid, polyethylene glycol propane diols-copolymer of poly lactic acid, polyvinyl alcohol, poly- One or several in aziridine, polyvinylpyrrolidone, starch, poly or poly-aspartate Kind.

From the amount improving surface holes in the range of 10-1000nm for the described diameter and/or internal holes and hole Footpath uniformity is set out, and further preferably has the hydrophily of preferable compatibility with polylactic resin A and organises Compound B.Specifically, can be ethylene glycol, glycerine, succinic acid, lactic acid, lactide, lactate, ATBC, triethyl citrate, ATEC, tributyl 2-acetylcitrate, three Acetin, Coronex, polyethylene glycol, polyethylene glycol oxide, polypropylene glycol, polyethylene glycol- Polypropylene glycol copolymers, PLGA-PEG-PLGA, polypropylene glycol-copolymer of poly lactic acid or poly- One or more in ethylene glycol-polypropylene glycol-copolymer of poly lactic acid.

The present invention, for the molecular weight of described hydrophilic organic compound B, does not particularly require, but From the mechanical property of film, preferred number average molecular weight is less than 100,000, further preferred number-average molecular weight Less than 50,000.The lower limit of number-average molecular weight is not particularly limited.

If above-mentioned film also has diameter and is more than 1 μm, and when being less than the internal holes in 100 μ m, energy Improve the poisture-penetrability of film further.Inventor finds, described micro-porous polylactic acid orientation film, with Polylactic resin A and hydrophilic organic compound B is 100 weight portion meters, can also contain 400 weight During incompatible component C of hydrophobicity within number, film can form described diameter and be more than 1 μm, and Less than the internal holes in 100 μ m.Incompatible component C of described hydrophobicity is selected from except described hydrophilic Property organic compound B beyond, and when 40-100 DEG C can with PLA formed heterogeneous structure material in One or more.Described when 40-100 DEG C can with PLA formed heterogeneous structure, refer to During arbitrary temperature within the temperature range of 40-100 DEG C, heterogeneous structure can be formed with PLA.

So-called heterogeneous structure, is the term that macromolecule association area is general, refers at a certain temperature, poly- Between compound and polymer, between polymer and micromolecular compound or deposit between polymer and inorganic matter System at two-phase system or more multiphase.Heterogeneous structure can be with light microscope, electron microscope, former The microscopic methods such as sub-force microscope directly judge, it is also possible to differential scanning calorimeter, dynamic mechanical properties The indirect methods such as analyzer judge.

Incompatible component C of described hydrophobicity, can be organic matter, it is also possible to be inorganic matter, or organic matter Mixture with inorganic matter.Specifically, incompatible component C of described hydrophobicity is selected from except described parent Beyond aqueous organic compounds B, one or more in following substances: carbon number is less than 100 The micromolecular compounds such as alkane, alkene, aromatic series, polyolefin, polyurethane, gathering in addition to PLA Ester, polyamide, polyimides, Merlon, polythiaether, polyethers, fluoropolymer, unsaturated tree The polymer such as fat, epoxy resin, acrylic resin or polystyrene, wood powder, cellulose, sisal hemp are fine Dimension or the animal fiber such as vegetative fiber, wool fiber such as bamboo fibre, aramid fibre or The organic synthetic fibers such as aromatic polyester fibres, glass fibre, asbestos fibre, carbon fiber, graphite fibre, Metallic fiber, potassium titanate crystal whisker, aluminium borate whisker, magnesium system whisker, silicon system whisker, wollastonite, Hai Pao Stone, asbestos, slag fibre, eakleite, ellestadite, gypsum fiber, silicon dioxide fibre, two Silica/alumina fiber, Zirconium oxide fibre, boron nitride fiber, silicon nitride fiber or boron fibre, glass Thin slice, non-bloating tendency mica, bloating tendency mica, graphite, metal forming, ceramic beads, talcum, clay, Mica, sericite, zeolite, bentonite, vermiculite, montmorillonite, dolomite, kaolin, micro mist silicic acid, Feldspar powder, potassium titanate, fine hollow glass ball, calcium carbonate, magnesium carbonate, calcium sulfate, titanium dioxide, The inorganic matters such as boehmite alumina, silica, gypsum, novaculite, dawsonite or carclazyte.

Incompatible component C of above-mentioned hydrophobicity also can carry out any form of surface modification or Interfacial compatibilization, To strengthen it with the interfacial adhesion between polylactic resin.

From the biodegradability consideration keeping or improving material, incompatible component C of described hydrophobicity is excellent Select biological degradation polyalcohol or inorganic filler.

Described hydrophobicity incompatible component C more preferably poly butyric ester, poly butyric valeric acid Ester, poly butyric capronate, poly butylene succinate, poly-succinic tetramethylene adipate, poly- Caprolactone, poly terephthalic acid tetramethylene adipate, poly terephthalic acid adipic acid propylene glycol ester, poly- Terephthalic acid (TPA) succinic acid-butanediol ester, poly-ethylene carbonate, polypropylene carbonate, polymerized thylene carbonate hexamethylene Ester, calcium carbonate, talcum powder, mica powder, zeolite, vermiculite, titanium dioxide, silica, calcium sulfate or One or more in montmorillonite.

In micro-porous polylactic acid orientation film of the present invention, the purpose of the present invention can be realized not hindering In the range of, add plasticizer, bulking agent, end-capping reagent, fire retardant, nucleator, antioxidant, lubrication Agent, antistatic additive, antifoggant, light stabilizer, ultra-violet absorber, pigment, mould inhibitor, antiseptic, Or one or more in the additive such as foaming agent.Described hydrophilic organic compound B and hydrophobicity are not In compatible components C, part be also used as plasticizer, nucleator, filler, lubricant, pigment, Or the additive such as dyestuff uses.

Described micro-porous polylactic acid orientation film, has preferable hydrophily, impregnates in the water of 25 DEG C After 10min, the water content of this film is the 1-50% of total film mass.

In described micro-porous polylactic acid orientation film, the weight average molecular weight of polylactic resin is 5-50 ten thousand, In order to meet the mechanical property of practicality, preferably 8-40 ten thousand, more preferably 10-30 ten thousand.

The present invention utilizes the hydrophily of hydrophilic organic compound, is preferably used described in the preparation of following method Micro-porous polylactic acid orientation film.

Step one: each raw material is blended by methods such as extrusion, banburying or mills.

Step 2: the blend that will obtain with step one, by curtain coating, blowing, calendering, mold pressing, squeezes Go out, moulding by casting prepares unorientating film.

Step 3: any one in following methods is prepared oriented film:

Method one

Described oriented film, is drawn through unidirectional or two-way by unorientating film while being heated by steam Stretch and prepare.

Method two

Described oriented film by unorientating film while liquid body heats, through uniaxial or biaxial stretching Prepare；Described liquid is selected from water or is more than 10 to mix water content in terms of liquid 100 weight portion The mixing liquid of weight portion.Described mixing liquid including but not limited to: water, ethanol, ethylene glycol or The mixed liquor (water content is more than 10%) of the one or more of liquid in glycerine.From price and green ring The concept protected is set out, preferably water.Clean level for water quality or water does not has particular/special requirement, clean from product It from the point of view of Jing, is preferred with more pure water, such as running water, deionized water or distilled water.

Method three

Oriented film takes out after being soaked in a liquid by unorientating film, while heated air heats, Prepare through uniaxial or biaxial stretching；Described liquid is selected from water or to mix liquid 100 weight Part meter water content is more than the mixing liquid of 10 weight portions.Described mixing liquid including but not limited to: water, The mixed liquor (water content is more than 10%) of the one or more of liquid in ethanol, ethylene glycol or glycerine. From the concept of price and environmental protection, preferably water.Clean level for water quality or water is not special Require, from the point of view of product is clean, be preferred with more pure water.Such as running water, deionization Water or distilled water.For the time of liquid infiltration, there is no special requirement, if fluid temperature is relatively low, Longer dip time can be selected, if fluid temperature is higher, in order to prevent the hydrolysis of PLA, can To select shorter dip time, generally 4s-10h.

In above-mentioned three kinds of methods, described unorientating film is before being stretched, and its water content is not important to Ask.But experiment shows, when water content is the 0.1-30% of gross mass, be conducive to described microporous structure Uniformity.

In above-mentioned three kinds of methods, the temperature of described stretching is 40-100 DEG C.From the angle improving processing stability Considering on degree, preferred draft temperature is 60-97 DEG C.

Can be by the drawing process parameters such as regulation formula and stretching ratio, control surface (and internal) hole The aperture in hole, the number average in the aperture in hole in the range of 10-1000nm for the described diameter is generally 100-800nm (is accurate to 10nm).Stretching ratio is bigger, and aperture is bigger.

Based on the above method, can also be again by general filming technology systems such as additional thermal finalizations Standby described micro-porous polylactic acid orientation film.

It is an advantage of the current invention that to prepare the nanoscale of the feature possessing spherical pore hole intensive, all even Micro-porous oriented film of micropore, and processing method is simply, at a high speed, need not use poisonous and harmful solvent, Environmental protection.This micro-porous oriented film can apply hygiene care, medical treatment, building, water process, The multiple fields such as agricultural, electronic product, packaging, decoration.

Detailed description of the invention

By following example, the present invention is described in more detail, but described embodiment is not constituted to this Bright restriction.

Embodiment is as follows, for all tests, without clearly with the method for testing of use in comparative example Illustrate to test temperature, then test at 25 DEG C:

Thickness: use instrument company 7050 of Sanyo type thickness gauge to measure, take the mean value of 9 data.

Weight average molecular weight and number-average molecular weight: use gel permeation chromatography to measure, with oxolane for flowing Phase, measures 3 times, averages.

Rate of perviousness: based on JIS Z0208:1976, humidity 90%.Measure 3 times, average.

<surface topography mensuration>

Surface topography is observed and is carried out at 25 DEG C.

Aperture d: being observed film surface by SEM (SEM), random shooting is not 5, the photo that co-located enlargement ratio is 10000 times is after ticking hole profile with pen, soft with image procossing Part ImageJ 1.46r calculates area S, the girth C of each surface holes of each surface holes, then calculates by formula (1) The aperture d (diameter of a kind of equivalence, i.e. equal with hole area diameter of a circle) in each hole:

$d=2\sqrt{\frac{S}{\mathrm{\&pi;}}}---\left(1\right);$

Average pore size (nano grade pore) d_n: press hole in the range of 10-1000nm for formula (2) calculated diameter Aperture averaging value,

$d_n=\frac{\mathrm{\&Sigma;d}}{n}---\left(2\right);$

Wherein, ∑ d be the aperture d in hole in the range of 10-1000nm for the aperture add and, n for participate in calculate 10-1000nm in the range of the number in hole, the number in the hole of general statistics is about at about 3500.

Pore-size distribution (nano grade pore) SD: first calculate volumetric average pore footpath d by formula (3-1)_v, then press Formula (3-2) calculated hole diameters is distributed SD,

$d_V=\frac{{\mathrm{\&Sigma;d}}^4}{{\mathrm{\&Sigma;d}}^3}---(3-1);$

$\mathrm{SD}=\frac{d_V}{d_n}---(3-2)$

Wherein, ∑ d⁴For hole in the range of 10-1000nm for the aperture aperture d 4 powers add and； ∑d³For hole in the range of 10-1000nm for the aperture aperture d 3 powers add and.

Area ratio (nano grade pore) S%: the area of surface holes in the range of 10-1000nm for the diameter accounts for The percentage of total surface area.Calculate by formula (4):

$S\%=\frac{\mathrm{\&pi;n}{\left(\frac{d_n}{2}\right)}^2}{\mathrm{\&Sigma;}{S}_m}---\left(4\right);$

Wherein, ∑ S_mObserve area sum for above-mentioned SEM.

What average circularity e was equal to girth square is multiplied by 4 π divided by area, and circularity e is based on formula (5) Calculate:

$e=\frac{C^2}{4\mathrm{\&pi;S}}---\left(5\right);$

When e is 1, figure is circle；E is bigger, and figure is bigger with circular gap.

The average circularity e of surface holes_sCalculate by formula (6):

$e_s=\frac{\mathrm{\&Sigma;e}}{n}---\left(6\right);$

Surface circular hole number percentage n_sCircle in surface holes in the range of 10-1000nm for %: the diameter The percentage of hole below 1.2 for the degree.Add up circularity in 1.2 diameter below at 10-1000nm In the range of accounting in surface holes in the range of 10-1000nm for all diameters for the surface holes.

<internal morphology mensuration>

Surface topography is observed and is carried out at 25 DEG C.

The means such as diamond cutter or ion polishing prepare smooth MD-ZD section, with SEM to this section Observe,

Aperture d: by statistics and the computational methods in aforementioned surfaces aperture, calculate the aperture of internal holes.

Average pore size (nano grade pore) d_n: press hole in the range of 10-1000nm for formula (2) calculated diameter Aperture averaging value.Wherein, ∑ d be the aperture d in hole in the range of 10-1000nm for the aperture add and.

Pore-size distribution (nano grade pore) SD: first calculate volumetric average pore footpath d by formula (3-1)_v, then press Formula (3-2) calculated hole diameters is distributed SD.

Area ratio (nano grade pore) S%: the area of internal holes in the range of 10-1000nm for the diameter accounts for The percentage of total surface area.Calculate by formula (4).

Hole girth C: by the computational methods of aforementioned surfaces hole girth, with film at MD-ZD and TD-ZD Hole on section calculates the girth of internal holes.

Average pore size (micrometer grade hole) d '_m: represent the aperture averaging in hole in 1-100 μ m for the diameter Value, is calculated by formula (7).

${d^{\&prime;}}_m=\frac{\mathrm{\&Sigma;}{d}^{\&prime;}}{m}---\left(7\right);$

Wherein, ∑ d ' be the aperture d in hole in 1-100 μ m for the aperture add and, m for participate in meter The number in the hole in the 1-100 μ m calculated, the quantity of this pores of general statistics is at about 50.

Sphericity is the ratio of the outer surface Ss and the external surface area Sp of particle of the ball equal with particle volume, I.e. φ s=Ss/Sp.Owing to the external surface area Sp of aspherical particle is necessarily more than the outer surface of equal-volume ball Long-pending SS, therefore φ s≤1.φ s value is less, illustrates that the shape of particle and the difference of ball are bigger.Film The sphericity of inside aperture, uses following methods to calculate: respectively with internal holes MD-ZD and TD-ZD cross section On the area S and girth C of hole make ball, its surface area is respectively SS_SAnd SS_C.With two balls Surface area ratio is as the sphericity φ s of this internal holes.The sphericity of internal holes, is calculated by formula (8-1):

With scientific and technical progress, it is also possible to calculate film internal holes according to other physics, mathematical method Sphericity, the sphericity calculating in this approach there may be some hole sphericity be less than 0.8, but As long as being the film that the ensemble average sphericity of internal holes is more than 0.8, also should belong in scope of the invention.

The average spherical degree φ s ' of internal holes: represent the flat of internal holes in the range of 10-1000nm for the aperture Equal sphericity.Calculate according to formula (8-2):

Inner circular hole number percentage n_sCircle in internal holes in the range of 10-1000nm for %: the diameter The percentage of hole below 1.2 for the degree.Statistics diameter more than 0.8 for the sphericity is at 10-1000nm In the range of accounting in internal holes in the range of 10-1000nm for all diameters for the internal holes.

Embodiment is as follows with the raw material of use in comparative example:

＜ polylactic resin ＞ (A)

A-1: PLA, 4042D, Natureworks company of the U.S..Weight average molecular weight 220,000.

A-2: PLA, 4060D, Natureworks company of the U.S..Weight average molecular weight 230,000.

＜ hydrophilic organic compound ＞ (B)

B-1: polyethylene glycol, number-average molecular weight 800, traditional Chinese medicines group of China.

B-2: PLA-PEG-PLA triblock copolymer, according to CN200810018621.7 Embodiment 1 manufacture.Number-average molecular weight 20,000.

Incompatible component ＞ of ＜ hydrophobicity (C)

C-1: poly butylene succinate, Bionolle 1020, Showa macromolecule company of Japan.

C-2: poly terephthalic acid tetramethylene adipate, Ecoflex C1200, BASF Corp. of Germany.

C-3: calcium carbonate, particle diameter 2.4-5.5 μm, fine powder Co., Ltd. altogether of Japan three.

Embodiment 1～6, comparative example 1～3

Raw material is pressed certain proportioning double screw extruder extruding pelletization, extrusion temperature 175-200 DEG C. Then, it is blow molded by single screw extrusion machine, prepare the unorientating film that thickness is 100 μm.Blowing temperature Spend 180-200 DEG C.And then, in the steam of 85 DEG C, unorientating film is stretched, taken To film as embodiment 1～7.In the hot-air of 85 DEG C, unorientating film is stretched, obtain Oriented film as a comparison case 1～3.Table 1 lists this film composition.At 25 DEG C, determine each thin The performance of film, is listed in table 1.

Embodiment 8～15, comparative example the 4th, 5

Raw material is pressed certain proportioning double screw extruder extruding pelletization, extrusion temperature 175-200 DEG C. Then, being cast by single screw extrusion machine, casting temperature 180-200 DEG C, preparing thickness is 120 μm Unorientating film.And then, in the water of 80 DEG C, the drawing process as listed by table 2 is to unorientating film Stretch, obtain oriented film.Table 2 lists this film composition.At 25 DEG C, determine each thin The performance of film, is listed in table 2.

Embodiment 16～21

Raw material is pressed certain proportioning double screw extruder extruding pelletization, extrusion temperature 175-200 DEG C. Then, being cast by single screw extrusion machine, casting temperature 180-200 DEG C, preparing thickness is 100 μm Unorientating film.And then, in the water of 80 DEG C, soak 30min.Again in the air of 90 DEG C, Unorientating film is stretched by the drawing process as listed by table 3, obtains oriented film.Table 3 lists This film forms.At 25 DEG C, determine the performance of each film, be listed in table 3.

Table 1

Table 1 (Continued)

Table 2

Table 2 (Continued)

Remarks: gradually two-way is the stretching of first MD direction, then the stretching of TD direction.

Table 3

All patent documents, the non-patent literature mentioned in this specification are incorporated to this all by way of reference Literary composition." multiple " mentioning in this specification comprise more than a kind of all situations, i.e. " one or more " Including one, two kinds, three kinds ... etc..This specification is recorded respectively for certain number range Limit and during lower limit, or when recording certain number range in the way of the upper limit and lower values, described in it Each upper limit and each lower limit can be combined as new number range, and this combines with being directly expressly recited The record form of number range should be considered to be identical.In the case without departing from the gist of the present invention, originally The present invention can be changed and improve by skilled person, and these are intended to be included within the scope of the present invention.

Claims (9)

1. a micro-porous polylactic acid orientation film, it is characterised in that: described oriented film has diameter and exists Surface holes in the range of 10-1000nm, the average circularity of described surface holes is less than 1.2.

2. micro-porous polylactic acid orientation film according to claim 1, it is characterised in that: described is straight Surface holes in the range of 10-1000nm for the footpath, the pore-size distribution of such surface holes is less than 2.0, such table The area sum of face accounts for more than the 20% of described micro-porous polylactic acid orientation film total surface area.

3. micro-porous polylactic acid orientation film according to claim 1, it is characterised in that: described is straight In surface holes in the range of 10-1000nm for the footpath, the surface holes number less than 1.2 for the circularity accounts for such surface More than the 80% of hole sum.

4. micro-porous polylactic acid orientation film according to claim 1, it is characterised in that: described orientation Film also has internal holes in the range of 10-1000nm for the diameter, and the sphericity of described internal holes is more than 0.8。

5. micro-porous polylactic acid orientation film according to claim 4, it is characterised in that: described is straight The pore-size distribution of internal holes in the range of 10-1000nm for the footpath is less than 2.0, the cross section face of such internal holes Long-pending accounting is more than 20%.

6. micro-porous polylactic acid orientation film according to claim 4, it is characterised in that: described inside The number of the internal holes in hole with the sphericity more than 0.8 accounts for more than 80%.

7. micro-porous polylactic acid orientation film according to claim 1, it is characterised in that: described micro-many Component containing following parts by weight in the polylactic acid orientation film of hole: polylactic resin A:40-99.9 weight Part, hydrophilic organic compound B:0.1-60 weight portion；Described hydrophilic organic compound B is selected from In water soluble or can one or more in organic compound swelling in water.

8. micro-porous polylactic acid orientation film according to claim 7, it is characterised in that: described is poly- Lactic acid Resin A is amorphism polylactic resin or crystalline polylactic acid resin and amorphism polylactic resin Mixture.

9. micro-porous polylactic acid orientation film according to claim 7, it is characterised in that: described parent Aqueous organic compounds B selected from ethylene glycol, glycerine, succinic acid, lactic acid, lactide, lactate, ATBC, triethyl citrate, ATEC, tributyl 2-acetylcitrate, three Acetin, Coronex, polyethylene glycol, polyethylene glycol oxide, polypropylene glycol, polyethylene glycol- Polypropylene glycol copolymers, PLGA-PEG-PLGA, polypropylene glycol-copolymer of poly lactic acid, poly-second Glycol-polypropylene glycol-copolymer of poly lactic acid, polyvinyl alcohol, ethylene imine, polyvinylpyrrolidone, One or more in starch, poly or poly-aspartate.