CN106065167A - A kind of micro-porous polylactic acid orientation thin film - Google Patents

Abstract

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

Description

A kind of micro-porous polylactic acid orientation thin 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 Can material etc., 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.

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

CN 201310185870.6 uses the method for particle-filled-stretching, it is provided that a kind of raw containing polylactic acid etc. Micro-porous oriented film of thing degradation polymer, the area of diameter surface holes in 0.2～7 μ m 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, Just softness is less than 40mm.Can be as moisture permeable waterproof film for health care field.

CN 201110414695.4 uses phase detachment technique, it is provided that a kind of aperture 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 polylactic acid formation powder body, described powder body It is bonded with each other by melted adhesion again, obtains the continuous poriferous structure between the 100-2000 μm of aperture, Can be used as absorbent material.

Empty structure subglobular in most micro-porous membrane, and there is spherical pore space structure meeting Cause the isotropism of thin film, certain applications may result in the limitation in certain applications.

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, uniform pore diameter and the void shape spherical micro-porous polylactic acid film of deviation.

Summary of the invention

Along with the range of application of micro-porous membrane constantly expands, it has been found that in prior art, micro-porous is gathered The defects such as the large scale aperture of lactic acid thin film, uneven pore-size distribution, mechanical property isotropism, limit Made its hygiene care, medical treatment, building, water process, agricultural, electronic product, pack, decoration etc. The application of multiple fields.

In order to solve the defect of prior art, the present invention provides a kind of micro-porous polylactic acid orientation thin 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 Thin film is in useful performance and character, such as film strength, toughness, the raising of the transparency；Depending on post processing Condition, it is possible to make thin film have heat-shrinkable.The orientation of thin film can be on unidirectional, two-way stretching-machine Carry out, it is also possible to the blow moiding method improved by double-membrane soaking method (bubble tube method) etc. is carried out.Detection thin 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 thin 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 more than 1.2.Relative to not The polylactic acid film of orientation, the polylactic acid film of orientation has more preferable intensity and storage stability.Surface The average circularity in the hole thin film more than 1.2, its surface holes deviation circle, there is the thin of this kind of pore structure Film, its mechanical property etc. has anisotropy.Being similar to, have the hole that deviation is circular, its draw ratio is big In 1, shape deviation is the biggest, and draw ratio is the biggest, the average aspect ratio of surface holes thin film more than 1.4 Belong to protection scope of the present invention.

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

The aperture of diameter nanoscale in the range of 10-1000nm and submicron order is not hindering steam On the premise of infiltration, it is possible to passing through of effective obstruction liquid water.

Further, the diameter of the present invention surface holes in the range of 10-1000nm, 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 thin film More than the 10% of total surface area, preferably more than 20%.

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

Increase the hole area sum of diameter surface holes in the range of 10-1000nm, 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 thin film total surface Long-pending more than 10%.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 20% of described thin film total surface area with On, more preferably more than 35%, the most preferably more than 45%.The area in aforementioned surfaces hole The upper limit is not particularly limited, and it such as can be below 70%.

Uniform pore diameter is conducive to improving the mechanical performance of thin film, the uniformity of water vapour permeability.In the present invention, The above-mentioned uniform pore diameter with diameter surface holes in the range of 10-1000nm, 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 such as can be more than 1.05.

Further, above-mentioned micro-porous polylactic acid film, its diameter surface in the range of 10-1000nm In hole, the circularity surface holes number more than 1.2 accounts for more than the 60% of such surface holes sum, and preferably 80% Above.The number with the circular hole of deviation accounts for the ratio of more than 60% in such surface holes, has this The film surface hole shape planting structure is consistent, it is ensured that the anisotropy of its entirety.

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

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

The pore-size distribution of described diameter internal holes in the range of 10-1000nm is less than 2.0, in such The area of section accounting in hole, portion is more than 10%.Uniform pore diameter is conducive to improving the mechanical performance, thoroughly of thin film The uniformity of wet performance.Described internal holes can weigh 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 thin film After going out MD-normal direction (ZD) section or TD-ZD section, with microscope (ultramicroscope or atom Force microscope etc.) observe this section, recycle image processing techniques, this pores can be added up at thin film Area sum on MD-ZD section or TD-ZD section accounts for the percentage ratio (area of section of this cross-sectional area Accounting).After statistical computation, with cross-sectional area for 100%, 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 10%.In view of improving moisture permeability further, In the present invention, above-mentioned diameter internal holes in the range of 10-1000nm further preferred more than 20%, then More preferably more than 35%, the most preferably more than 45%.The area of section in aforementioned inner hole accounts for The upper limit of ratio is not particularly limited, and it such as can be below 70%.In view of the uniformity of raising thin film, In the present invention, the uniform pore diameter of above-mentioned diameter internal holes in the range of 10-1000nm, pore-size distribution is excellent Choosing, less than 2.0, is further preferably no larger than 1.5, and the most preferably smaller than 1.3.Under aforementioned aperture distribution Limit is not particularly limited, and they such as can be more than 1.1.

The number of the described diameter internal holes with the sphericity less than 0.8 in the range of 10-1000nm Mesh accounts for more than 60%, and preferably more than 80%.The number in the hole with subglobular accounts for the ratio of more than 60% Example, the film surface hole shape with this kind of structure differs, it is ensured that the anisotropy of its entirety.

In view of the poisture-penetrability of raising thin film further, in the present invention, above-mentioned micro-porous polylactic acid orientation is thin In film, it is also possible to there is diameter more than 1 μm, and less than the internal holes in 100 μ m.Can be above Described in method add up.After statistical computation, with cross-sectional area for 100%, above-mentioned in the present invention There is diameter 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 such as less than 30%.

Described micro-porous polylactic acid orientation thin film, containing the component of following parts by weight: polylactic resin A:40-99 weight portion, hydrophilic organic compound B:0.1-60 weight portion；Described hydrophilic 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 polylactic acid (polylactide) or lactic acid are with one or more in the copolymer of other chemical constitutions.

The preferably molecular structure of polylactic acid is, by the 80-100mol% of L lactic acid or D lactic acid with respective Enantiomer 0-20mol% constitute molecular structure.Above-mentioned polylactic resin can be from L lactic acid or D breast One or both in acid 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 The Study of Meso-Lactide carrying out cyclic dimer and obtain and D lactide and the raceme of L lactide 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 that lactic acid is 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 binary or the copolymer of 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 maybe 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 thin film Ratio.One of method is, by differential scanning calorimetric analysis (DSC).Film sample is carried out component divide From, after isolating polylactic acid component, carry out DSC test, be can be determined that by the size calculating melting enthalpy Crystalline polylactic acid resin and the ratio of amorphism polylactic resin.

About 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 The volumetric expansion of more than 10% is there is in compound in 100g water.

Described hydrophilic organic compound B can be small molecular organic compounds, it is also possible to be macromole 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, glycerol or propylene glycol The esters such as compound, lactide, caprolactone, lactate, citrate, glyceride or Coronex Micromolecular compound, Polyethylene Glycol, polyethylene glycol oxide, polypropylene glycol, polyethylene glycol propylene glycol are altogether The polyether-based polymers such as polymers or polyethers-polyolefin copolymer, polyether-polyester copolymer, polyether-type gather Urethane, polyvinyl alcohol, polymine, polyvinylpyrrolidone, polyacrylamide, poly, Diallyl quaternary ammonium polymer, poly-aspartate, poly-epoxy succinic acid, Carboxymethylinulin, starch or One or more in its derivant, cellulose ether, chitin, xanthan gum or plant gum.

From the ready availability consideration of raw material, described hydrophilic organic compound B be preferably ethylene glycol, glycerol, Succinic acid, lactic acid, lactide, lactate, tributyl citrate, triethyl citrate, acetyl Fructus Citri Limoniae 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 propylene glycol-copolymer of poly lactic acid, polyvinyl alcohol, poly- One or several in aziridine, polyvinylpyrrolidone, starch, poly or poly-aspartate Kind.

Diameter surface holes in the range of 10-1000nm described in improve and/or the amount of internal holes and hole Footpath uniformity is set out, and further preferably has the hydrophilic of the preferable compatibility with polylactic resin A and organises Compound B.Specifically, can be ethylene glycol, glycerol, succinic acid, lactic acid, lactide, lactate, Tributyl citrate, triethyl citrate, acetyl triethyl citrate, 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, particularly requirement, but From the mechanical property of thin 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 thin film also has diameter more than 1 μm, and when being less than the internal holes in 100 μ m, energy Improve the poisture-penetrability of thin film further.Inventor finds, described micro-porous polylactic acid orientation thin film, with Polylactic resin A and hydrophilic organic compound B is 100 weight portion meters, it is also possible to containing 400 weight During incompatible component C of hydrophobicity within number, thin film can form described diameter 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 polylactic acid formed heterogeneous structure material in One or more.Described when 40-100 DEG C can with polylactic acid formed heterogeneous structure, refer at 40-100 DEG C Within the temperature range of arbitrary temperature time, can with polylactic acid formed heterogeneous structure.

So-called heterogeneous structure, is the term that macromolecule association area is general, refers at a certain temperature, poly- Deposit between compound and polymer, between polymer and micromolecular compound or between polymer and inorganic matter System at two-phase system or more heterogeneous.Heterogeneous structure can use optical microscope, ultramicroscope, 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 analyser judge.

Incompatible component C of described hydrophobicity, can be Organic substance, it is also possible to be inorganic matter, or Organic substance 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 polylactic acid Ester, polyamide, polyimides, Merlon, polythiaether, polyethers, fluoropolymer, unsaturated tree The polymer such as fat, epoxy resin, acrylic resin or polystyrene, wood powder, cellulose, Folium Agaves Sisalanae fibre 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 Muscovitum, bloating tendency Muscovitum, graphite, metal forming, ceramic beads, Talcum, clay, Muscovitum, sericite, zeolite, bentonite, Vermiculitum, montmorillonite, dolomite, Kaolin, micropowder 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, silicon oxide, Gypsum Fibrosum, novaculite, dawsonite or hargil.

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

From keeping or the biodegradability consideration of raising 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 alkyl caproate, poly butylene succinate, poly-succinic tetramethylene adipate, poly- Caprolactone, poly terephthalic acid tetramethylene adipate, poly terephthalic acid adipic acid propylene glycol ester, poly- P-phthalic acid succinic acid-butanediol ester, poly-ethylene carbonate, polypropylene carbonate, polymerized thylene carbonate hexamethylene Ester, calcium carbonate, Pulvis Talci, mica powder, zeolite, Vermiculitum, titanium dioxide, silicon dioxide, calcium sulfate or One or more in montmorillonite.

In micro-porous polylactic acid orientation thin 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, UV absorbent, pigment, antifungus agent, antibacterial, 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 thin film, has preferable hydrophilic, impregnates in the water of 25 DEG C After 10min, the water content of this thin film is the 1-50% of total film mass.

In described micro-porous polylactic acid orientation thin 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 hydrophilic of hydrophilic organic compound, is preferably used described in the preparation of following method Micro-porous polylactic acid orientation thin 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 being cast, be blow molded, roll, molding, squeezes Go out, moulding by casting prepares unorientating film.

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

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 liquid body heat while, through uniaxial or biaxial stretching Prepare；Described liquid is more than 10 selected from water or 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 glycerol.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 From the point of view of Jing, it is preferred with the purest water, such as tap 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 glycerol. From price and the concept of environmental protection, preferably water.Clean level for water quality or water is the most special Requirement, from the point of view of product cleaning, is preferred with the purest water.Such as tap water, deionization Water or distilled water.For the time of liquid infiltration, there is no special requirement, if temperature of liquid is relatively low, Longer dip time can be selected, if temperature of liquid is higher, in order to prevent the hydrolysis of polylactic acid, 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.

Surface (and internal) hole can be controlled by the regulation drawing process parameter such as formula and stretching ratio The aperture in hole, the number average in the aperture in described diameter hole in the range of 10-1000nm is generally 100-800nm (is accurate to 10nm).Stretching ratio is the biggest, and aperture is the biggest.

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

It is an advantage of the current invention that to prepare the nanoscale of the feature possessing spherical pore hole intensive, the most 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, Agricultural, electronic product, pack, the multiple fields such as decoration.

Detailed description of the invention

By following example, the present invention is described in more detail, but described embodiment is not constituted 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 meansigma methods 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: observing film surface by scanning electron microscope (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: by formula (2) calculated diameter hole in the range of 10-1000nm 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, 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 distribution SD,

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

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

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

Area ratio (nano grade pore) S%: the area of diameter surface holes in the range of 10-1000nm accounts for The percentage ratio 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_mArea sum is observed for above-mentioned SEM.

Average circularity e square is multiplied by 4 π divided by area equal to girth, 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 the biggest, and figure is the biggest 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 percent n_sCircle in %: diameter surface holes in the range of 10-1000nm The percent of degree hole below 1.2.Add up circularity in 1.2 diameter below at 10-1000nm In the range of surface holes accounting in all diameters surface holes in the range of 10-1000nm.

<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, the properties enumerated in the present invention be to use ion polishing method prepare smooth MD-ZD section carries out test and obtains.

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: by formula (2) calculated diameter hole in the range of 10-1000nm Aperture averaging value.Wherein, ∑ d be hole in the range of 10-1000nm, the aperture aperture d 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 distribution SD.

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

Hole girth C: by the computational methods of aforementioned surfaces hole girth, with thin 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 diameter hole in 1-100 μ m 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, 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 granule 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 the least, illustrates that the shape of granule is the biggest with the difference of ball.Thin 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):

Progress along with science and technology, it is also possible to calculate thin film internal holes according to other physics, mathematical method Sphericity, the sphericity calculated in this approach there may be the sphericity of some hole less than 0.8, but As long as be internal holes ensemble average sphericity more than 0.8 thin film, also should belong in scope of the invention.

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

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

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

＜ polylactic resin ＞ (A)

A-1: polylactic acid, 3052D, Natureworks company of the U.S..Weight average molecular weight 200,000.

A-2: polylactic acid, 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 400, 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 butyric-hydroxyl valerate, ENMAT Y1000P, Ningbo Tian An biomaterial has Limit company.

C-3:5A zeolite powder, Shanghai zeolite molecular sieve company.

Embodiment 1～9, comparative example 1～3

By raw material by certain proportioning double screw extruder extruding pelletization, extrusion temperature 175-200 DEG C. Then, it is blow molded by single screw extrusion machine, prepares the unorientating film that thickness is 140 μm.Blowing temperature Spend 180-200 DEG C.And then, in the steam of 85 DEG C, unorientating film is stretched, taken To thin 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 thin film composition.At 25 DEG C, determine each thin The performance of film, is listed in table 1.

Embodiment 10～19, comparative example 4,5

By raw material by 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 thin film composition.At 25 DEG C, determine each thin The performance of film, is listed in table 2.

Embodiment 20～27

By raw material by 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 140 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 thin film forms.At 25 DEG C, determine the performance of each thin film, be listed in table 3.

Table 1

Table 1 (Continued)

Table 2

Table 2 (Continued)

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

Table 3

All patent documentations, the non-patent literature mentioned in this specification are incorporated to this most by way of reference Literary composition." multiple " mentioned in this specification comprises 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 numerical range Limit and during lower limit, or when recording certain numerical range in the way of the upper limit and lower values, described in it Each upper limit and each lower limit can combination in any be new numerical range, and this combines with being directly expressly recited The record form of numerical 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 thin 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 more than 1.2.

Micro-porous polylactic acid orientation thin film the most according to claim 1, it is characterised in that: described is straight Footpath surface holes in the range of 10-1000nm, 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 10% of described micro-porous polylactic acid orientation thin film total surface area.

Micro-porous polylactic acid orientation thin film the most according to claim 1, it is characterised in that: described is straight In the surface holes in the range of 10-1000nm of the footpath, the circularity surface holes number more than 1.2 accounts for such surface More than the 60% of hole sum.

Micro-porous polylactic acid orientation thin film the most according to claim 1, it is characterised in that: described orientation Thin film also has diameter internal holes in the range of 10-1000nm, and the sphericity of described internal holes is less than 0.8。

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

Micro-porous polylactic acid orientation thin film the most according to claim 4, it is characterised in that: described inside The number of the internal holes in hole with the sphericity less than 0.8 accounts for more than 60%.

Micro-porous polylactic acid orientation thin film the most according to claim 1, it is characterised in that: described micro-many Containing the component of following parts by weight in the polylactic acid orientation thin 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.

Micro-porous polylactic acid orientation thin film the most 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.

Micro-porous polylactic acid orientation thin film the most according to claim 7, it is characterised in that: described parent Aqueous organic compounds B selected from ethylene glycol, glycerol, succinic acid, lactic acid, lactide, lactate, Tributyl citrate, triethyl citrate, acetyl triethyl citrate, 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, polymine, polyvinylpyrrolidone, One or more in starch, poly or poly-aspartate.