Background technology
The problem of non-renewable and non-degradable of petroleum based material is not present in poly-lactic acid material, is expected to take in many fields
For traditional non-renewable petroleum base high polymer material (such as polypropylene, polyamide, polyester).PLA is with natural reproducible resource
(such as corn, wheat) is raw material, it is fermented, polymerization and obtain, can be with degradable into dioxy when discarded without the use of petroleum resources
Change carbon and water, environmental pollution will not be caused.The advantages of based on more than PLA, PLA has broad application prospects.
But the relatively low softening temperature of PLA and facile hydrolysis limit its large-scale commercial application.It is such as poly-
Lactic acid, which cannot be used for preparing, the packing containers such as lunch box, the cup of heat resistant requirements, can not also be used as engineering plastics in automobile, electricity
Sub- electrical component etc. is applied.High temperature facile hydrolysis limits application of the acid fiber by polylactic in textile industry.Due to poly-
Acid fiber easily hydrolyzes, and is acutely hydrolyzed when higher temperature dyes, and fibrous mechanical property is impaired serious, so acid fiber by polylactic
Relatively low temperature can only be used to dye, cause the dye-uptake of dyestuff low, fabric can only obtain shallower color.
Ikada etc. is in document Macromolecules 1987,20:Reported first in 904-906 and pass through PLLA
(PLLA) and the blending of dextrorotation PLA (PDLA) can form the crystallization of vertical structure, and the stereoscopic composite fusing point is higher than common PLA
30~60 DEG C.Therefore Many researchers are want to improve the performance of PLA by forming polylactic acid stereoscopic crystallization.
Presently disclosed most of polylactic acid stereoscopic spinning process are, it is necessary to use nucleator.Publication number CN 101805941A
Report a kind of method that polylactic acid fiber with high melting point is prepared using PLLA and PDLA blend melt spinnings.This method adds
0.01wt%~5wt% nucleator, prepared acid fiber by polylactic fusing point are 209 DEG C;CN 102409432A disclose it is a kind of with
Alkyl fatty race salt carries out the method that PLLA, PDLA blend melt spinning prepare high heat-proof polylactic acid fiber as nucleator.Should
Fibers melt temperature has ironability more than 190 DEG C, and at 170 DEG C;CN 101528994A disclose one kind with phosphate
Metal salt carries out the method that PLLA, PDLA blend melt spinning prepare acid fiber by polylactic, the heat resistance of the fiber as nucleator
It is excellent with thermal shrinkage.It is configured to however, the addition of nucleator is stood in promotion, is often dropped while improving material thermal resistance
The mechanical property of low material.CN 1400343A report a kind of vertical structure fiber of PLLA and PDLA blending, and the fiber is below 90 DEG C
Intensity be 0.8cN/dtex.But the preparation of the fiber needs very high spinning speed, and complicated hot gas spring condition.It is above-mentioned
Complexity of the method due to technique or the high request to equipment, are all difficult to industrialization promotion.
Vertical structure rate is higher, and the heat resistance and hydrolytic resistance of polylactic acid stereoscopic composite are better.When PLLA and PDLA is mixed
Vertical structure crystallization is readily formed, while can also form homogeneous crystallization.Therefore, simple mixing is extremely difficult to 100% vertical structure
Rate.Therefore, the height for developing a kind of easy large-scale promotion of high-efficient simple founds structure rate (vertical structure rate refers to vertical structure crystallization and accounts for total crystallization
Ratio) the preparation method of polylactic acid stereoscopic composite have great importance.
The content of the invention
It is existing to overcome present invention aims at a kind of preparation method of high vertical structure rate polylactic acid stereoscopic composite of offer
The defects of technology is present, meet the needs of people.
Described height founds the preparation method of structure rate polylactic acid stereoscopic composite, comprises the following steps:
(1) pre- vertical structure:Described PLLA (PLLA) and dextrorotation PLA (PDLA) are dissolved in a solvent respectively,
Then two kinds of solution are mixed, the pre- vertical structure thing of PLA of solvent acquisition solid-state is removed in then volatilization;Or will be described left-handed poly-
In a solvent, solvent is removed in then volatilization for lactic acid (PLLA) and dextrorotation PLA (PDLA) co-dissolve, obtains PLLA/PDLA mixing
Material, the pre- vertical structure thing of PLA of as solid-state, the pre- vertical structure thing of PLA of the solid-state can be plastics, film, fiber or
Using PLA as matrix or the composite of reinforcement;
Preferably, the weight ratio of described PLLA (PLLA) and dextrorotation PLA (PDLA) is 10:90~90:
10;
Preferably, the weight average molecular weight of described PLLA (PLLA) and dextrorotation PLA (PDLA) is 50,000~35
Ten thousand;
Preferably, the weight average molecular weight ratio of described PLLA (PLLA) and dextrorotation PLA (PDLA) is 1:6 arrive
6:1;
Term " the ratio between weight average molecular weight " refers to the ratio between PLLA and PDLA molecular size range, if PLLA is that 300,000, PDLA is
100000, the ratio between weight average molecular weight is 3:1;
Described solvent in the organic solvents such as chloroform, tetrahydrofuran, dioxane, hexafluoroisopropanol it is a kind of with
On;
(2) structure is found entirely:By temperature of the pre- vertical structure thing of PLA of the solid-state of step (1) acquisition at 170~230 DEG C, tension force
For the vertical 0~120min of structure of heat under 0.3~0.6cN/dtex, room temperature is finally cooled to, rate of temperature fall is 1~20 DEG C/min, the mistake
Cheng Zhong, pre- vertical structure thing keep solid forms, obtain described height and found structure rate polylactic acid stereoscopic composite;
Further, preparation method of the invention, comprises the following steps:
(1) PLLA (PLLA) and dextrorotation PLA (PDLA) are dissolved in solvent respectively, it is then molten by two kinds again
Liquid mixes, and is paved into film, and volatilization removes solvent, obtains PLLA/PDLA compounds, then injects described PLLA/PDLA compounds
Melting extrusion in extruder, collection obtain as-spun fibre, 2.5~3.5 times of the drawing-off at 100 DEG C~120 DEG C by as-spun fibre, so
Afterwards by the product after drawing-off, 20~120 DEG C, preferably 20~30 DEG C are cooled to, rate of temperature fall is 1~20 DEG C/min, obtains drawing-off
The acid fiber by polylactic of cooling afterwards, it is the pre- vertical structure thing of PLA of solid-state;
Wherein:Screw rod area temperature is 175~240 DEG C, and spinneret temperature is 230 DEG C~235 DEG C, spinning speed 800m/
min;
Preferably, the weight ratio of described PLLA (PLLA) and dextrorotation PLA (PDLA) is 10:90~90:
10;
Preferably, the weight average molecular weight of described PLLA (PLLA) and dextrorotation PLA (PDLA) is 50,000~35
Ten thousand;
Preferably, the weight average molecular weight ratio of described PLLA (PLLA) and dextrorotation PLA (PDLA) is 1:6 arrive
6:1;
Term " the ratio between weight average molecular weight " refers to the ratio between PLLA and PDLA molecular size range, if PLLA is that 300,000, PDLA is
100000, the ratio between weight average molecular weight is 3:1;
Described solvent in the organic solvents such as chloroform, tetrahydrofuran, dioxane, hexafluoroisopropanol it is a kind of with
On;
(2) by the acid fiber by polylactic after drawing-off at 170~230 DEG C, preferably 190~205 DEG C, tension force is 0.3~0.6cN/
0~120min, preferably 40~60min are kept under dtex, carries out secondary vertical structure, described height is obtained and founds structure rate polylactic acid stereoscopic
Compound, for a kind of high vertical structure rate polylactic acid stereoscopic fiber;
Term " tension force " is defined as follows:When object under tension acts on, it is present in inside it and perpendicular to two adjacent parts
Mutual tractive force on contact surface;
Described height founds structure rate polylactic acid stereoscopic composite, when being measured with differential scanning calorimeter, has single
Melting peak, and the melting peak temperature be more than 200 DEG C, it is preferred that when being measured with differential scanning calorimeter, have it is single
Melting peak, and the melting peak temperature be 218~228 DEG C;With XRD determining only have diffraction maximum that vertical structure crystallizes (2 θ=12 °,
21 °, 24 °), without the diffraction maximum (2 θ=16 °) homogeneously crystallized;Crystallinity is 30~60%, and preferably crystallinity is 48~53%;
Softening temperature is 125~165 DEG C, preferably 149~153 DEG C;Fusing point be 200~240 DEG C, preferably 218~224
℃;
After hydrolyzing 1h in 130 DEG C, pH 5 solution, stretching strength retentivity is 65%~95%, preferably 87%
~92%;
By described height stand structure rate polylactic acid stereoscopic fiber using method well known in the art carry out woven, knitting or
It is non-woven, you can the height for obtaining other forms founds structure rate polylactic acid stereoscopic composite, available for clothes, home textile product, women and children
Amenities and industrial nonwoven cloth etc.;
For the present invention without using any nucleator and other additives, products obtained therefrom is 100% polylactic acid article, and technique is simple
It is single, it is adapted to large-scale production.The vertical structure rate that described height founds structure rate polylactic acid stereoscopic composite is 100%, and heat resistance is excellent
It is good.In addition, it is 65%~95% that the product hydrolyzes 1h post-tensioning strength retention in 130 DEG C, pH 5 solution, hydrolytic resistance
It is excellent.
The polylactic acid stereoscopic composite of vertical structure rate 100% prepared by the inventive method has single melting peak, and molten
Melt temperature more than 200 DEG C.Its softening temperature is 125~165 DEG C, far above common PLA fibers (60~120 DEG C).The poly- breast
It is 65%~95% that sour stereoscopic composite hydrolyzes 1h post-tensioning strength retention in 130 DEG C, pH 5 solution, far above common
PLA products.