CN115637034A - Flame-retardant modified polylactic acid compound and preparation method thereof - Google Patents
Flame-retardant modified polylactic acid compound and preparation method thereof Download PDFInfo
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Abstract
The invention provides a flame-retardant modified polylactic acid compound and a preparation method thereof, the flame-retardant modified polylactic acid compound is obtained by modifying polylactic acid with a flame retardant, the limiting oxygen index, the vertical combustion performance and the anti-dripping property of the phosphorus-containing flame retardant are greatly improved under the condition of adding a small amount of the phosphorus-containing flame retardant, the ignition time is prolonged, the flame retardant property of the polylactic acid is greatly improved, the scale and the loss of fire are reduced, meanwhile, the thermal property and the mechanical property of the modified polylactic acid compound are not influenced by the addition of the phosphorus-containing flame retardant, and the flame-retardant modified polylactic acid compound still has good crystallinity, spinnability and post-processing property and has good application prospect.
Description
Technical Field
The invention relates to the field of polymer flame retardance, in particular to a flame-retardant modified polylactic acid compound and a preparation method thereof.
Background
The application field of the l-polylactic acid is as wide as other melt-processed polymers and is a biodegradable polymer, and therefore, from the beginning of the discovery, the application thereof is mainly focused on the biodegradable field such as disposable medical supplies, disposable tableware, agricultural films, packaging materials, and the like. With the technological advances and cost reductions, it is expected that the amount of applications in the fields of disposables, apparel, household and public textiles, etc. will increase.
Since PLLA has a limited oxygen index almost the same as that of PET and PA6, and its flammability also affects the safety of living and working places, especially, in a large number of textiles such as clothes, curtains, carpets, sofas and ornaments in living rooms and public places, it is important to improve the flame retardancy of PLLA to improve the safety of people's lives and properties.
In recent years, researchers at home and abroad have tried to use nano inorganic flame retardant, phosphorus/nitrogen flame retardant, intumescent flame retardant, boron flame retardant, metal catalyst and the like for flame retardant modification research of PLLA, and some new composite flame retardant systems are developed. Xuanheroic et al added 20% pentaerythritol phosphate (PEPA) to PLLA to increase the limiting oxygen index of PLLA to 26% and the UL94 test passed V-2. Lei Song et al found that 25wt% intumescent flame retardants (PEPA and melamine phosphate) only achieved PLLA to a V-1 rating, while PLLA vertical burn tests of 20wt% intumescent flame retardants plus 5wt% polyhedral oligomeric silsesquioxane passed UL94V-0 rating. Wang Deyi et al synthesized flame-retardant PPLA by chain extension of a dihydroxy-terminated prepolymer (lactic acid) using ethyl dichlorophosphate as a chain extender, and adding 5wt% of PPLA gave PLLA an LOI value of 25% and a UL94V-0 rating. Jeng Jian et al react diphenolic acid with PEPA and then polycondensed with phenyl phosphine dichloride to obtain BPPT; the limited oxygen index of PLLA reached 33.7% with the addition of 4% BPPT, and the vertical burn passed UL94V-0 rating, but the mechanical properties decreased by about 24%.
The research improves the flame retardant property of PLLA, but the addition of a large amount of flame retardant reduces the mechanical property and the processing property, particularly the spinnability, of the polymer. The Naphn, liu Ting and the like use PEPA to improve the flame retardant property of PA6, and have good spinnability and mechanical property. And the like, adding 9wt% of [ (6-oxo-6H-dibenzo [ c, e ] [1,2] oxaphosphorin-6-yl) methyl ] succinic acid into PLLA (Poly lactic acid), wherein the LOI value can reach 29%, the vertical burning test passes UL94V-0 grade, and the fiber has better spinnability, but the crystallization property and the melting point of the fiber are reduced.
Compared with the Nature Works injection molding grade PLLA, the modified spinning grade PLLA has good spinnability, and the flame retardant property is improved to a certain extent, but the LOI is still lower (21%), the vertical combustion test can only pass UL 94V-2 grade, and the flame retardant property needs to be further improved.
Disclosure of Invention
Based on the above technical background, the present inventors have made a keen search and, as a result, have found that: the phosphorus-containing flame retardant is adopted to carry out flame-retardant modification on the polylactic acid in a melt blending mode, the limiting oxygen index, the anti-dripping property and the vertical combustion property of the polylactic acid compound are greatly improved under the condition of adding a small amount of phosphorus-containing flame retardant, the ignition time is prolonged, and the polylactic acid compound is endowed with self-extinguishing property.
The first aspect of the invention provides a flame-retardant modified polylactic acid compound, which is obtained by modifying polylactic acid with a phosphate flame retardant;
the phosphate flame retardant is selected from one or more of pentaerythritol phosphate, triethyl phosphate, tributyl phosphate, triphenyl phosphate and triphenyl phosphite.
The second aspect of the invention is to provide a preparation method of the flame-retardant modified polylactic acid compound of the first aspect of the invention, which takes polylactic acid and phosphate ester flame retardant as raw materials to carry out melt blending.
Drawings
FIG. 1 shows DSC curves of the products obtained in examples 2 to 6 and comparative example 1 and PEPA;
FIG. 2 shows TGA curves of the products prepared in example 3 and comparative example 1, as well as PEPA;
FIG. 3 shows DTA curves for the products obtained in example 3 and comparative example 1 and PEPA;
FIG. 4a shows test curves for the heat release rates of the products prepared in examples 1-3 and comparative example 1;
FIG. 4b shows test curves for the heat release rates of the products prepared in examples 4-6 and comparative example 1;
FIG. 5 shows test curves of total heat release of products prepared in examples 1,2, 6 and comparative example 1;
FIG. 6 shows test curves for the total smoke emissions of the products prepared in examples 3-6 and comparative example 1;
FIG. 7 shows mass loss rate curves upon combustion for examples 4-6 and comparative example 1;
fig. 8 shows scanning electron micrographs of the residue after cone calorimetry tests for example 2, example 4 and example 6.
Detailed Description
The present invention will be described in detail below, and features and advantages of the present invention will become more apparent and apparent with reference to the following description.
The invention provides a flame-retardant modified polylactic acid compound, which is obtained by modifying polylactic acid with a phosphate flame retardant.
The polylactic acid is selected from one or two of levorotatory polylactic acid and dextrorotatory polylactic acid, and preferably levorotatory polylactic acid (namely PLLA).
The phosphate flame retardant is selected from one or more of pentaerythritol phosphate (PEPA), triethyl phosphate, tributyl phosphate, triphenyl phosphate and triphenyl phosphite, preferably selected from one or more of pentaerythritol phosphate and triphenyl phosphite, and more preferably pentaerythritol phosphate. The phosphorus content of the phosphate ester flame retardant is 15-20%.
The inventor finds that the flame retardant has the function of promoting carbon formation on polylactic acid, can effectively improve the performances of the polylactic acid such as limited oxygen index, anti-dripping property, vertical combustibility and the like, increases the ignition difficulty and self-extinguishing property of the polylactic acid in the air, reduces the scale and loss of fire, and also finds that the addition of the flame retardant does not influence the glass transition temperature, the melt crystallization temperature, the melt enthalpy, the thermal decomposition temperature, the mechanical property, the spinning property and the post-processing property of the polylactic acid, and simultaneously improves the crystallization property. Compared with the unmodified polylactic acid fiber, the elongation at break and the breaking strength of the polylactic acid fiber prepared by the polylactic acid fiber are not obviously changed, and the breaking strength still meets the textile requirement.
The phosphorus content in the flame-retardant modified polylactic acid compound is 1000-22000 ppm, preferably 1500-21000 ppm, more preferably 1700-21000 ppm.
The phosphorus content is too low, the flame retardant property of the polylactic acid is not obviously improved, the flame retardant property improving effect of the polylactic acid is gradually improved along with the increase of the phosphorus content, but the other properties of the polylactic acid are influenced when the phosphorus content is too high.
The phosphate ester flame retardant accounts for 0.5-20% of the flame-retardant modified polylactic acid compound, preferably 0.7-15% of the flame-retardant modified polylactic acid compound, and more preferably 1-12% of the flame-retardant modified polylactic acid compound.
The inventors have found that a good flame retardant effect can be achieved by adding a small amount of the flame retardant to polylactic acid, and that the addition amount does not affect other properties of the polylactic acid, such as mechanical properties, spinnability, and post-processability.
The flame-retardant modified polylactic acid compound is prepared by melt blending of a phosphate flame retardant and polylactic acid, wherein the blending temperature is 150-210 ℃, preferably 160-200 ℃, and more preferably 170-190 ℃.
The modified flame-retardant modified polylactic acid compound has good spinnability, and compared with unmodified polylactic acid, the spinning temperature of the modified flame-retardant modified polylactic acid compound is not obviously changed. The spinning temperature of the flame-retardant polylactic acid compound is 160-215 ℃, the pressure of a spinning assembly is kept at 6.6MPa, the winding speed of a parallel drafting machine is 300-500 m/min, and the drafting multiple is 3-3.5 times.
The breaking strength of the flame-retardant modified polylactic acid compound is 58-74 MPa, the breaking elongation is 6.6-9.5%, and the initial modulus is 8.2-8.7 GPa.
The flame-retardant modified polylactic acid compound has the maximum limit oxygen index of 35 percent, has the melt-drip resistance, has the maximum vertical combustion grade UL-94 and V-0 grade, has the ignition time delay of about 25s, and has the minimum self-extinguishing time of 0s after being away from a fire, namely, is quenched immediately after being away from the fire.
The second aspect of the invention is to provide a method for preparing the flame-retardant modified polylactic acid compound of the first aspect of the invention, wherein the method takes polylactic acid and phosphate ester flame retardant as raw materials to carry out melt blending.
The polylactic acid is selected from one or two of levorotatory polylactic acid and dextrorotatory polylactic acid, and preferably is levorotatory polylactic acid.
The phosphate flame retardant is selected from one or more of pentaerythritol phosphate (PEPA), triethyl phosphate, tributyl phosphate, triphenyl phosphate and triphenyl phosphite, preferably selected from one or more of pentaerythritol phosphate and triphenyl phosphite, and more preferably selected from pentaerythritol phosphate.
The mass ratio of the phosphate flame retardant to the polylactic acid is (0.1-20): (80-99.9), preferably the mass ratio is (0.5-15): (85-99.5), and more preferably the mass ratio of (1-12): (88 to 99).
Preferably, before melt blending, the polylactic acid and the flame retardant are preferably subjected to vacuum drying, so that hydrolysis of the polylactic acid in a subsequent blending process is avoided or reduced, and the performance of the flame-retardant modified polylactic acid compound is improved.
The drying temperature is 50-70 ℃, preferably 60 ℃, and the drying time is 5-20 hours, preferably 10-15 hours.
The blending temperature is 150-210 ℃, preferably 160-200 ℃ and more preferably 170-190 ℃.
The blending time is 2-10 min, preferably 3-8 min, and more preferably 4-7 min.
The flame retardant and the polylactic acid in the modified polylactic acid compound obtained under the blending temperature and time conditions are uniformly mixed, the flame retardant effect on the polylactic acid is good, and meanwhile, stress concentration cannot be formed in a polylactic acid matrix to influence the mechanical property and the thermal property of the polylactic acid.
According to a preferred embodiment of the present invention, the melt blending is preferably carried out in a twin-screw extruder, the speed of which is 120 to 250r/min, preferably 150 to 220r/min, more preferably 170 to 200r/min.
In the blending process, the temperature of each area of the screw is (170-200) DEG C- (170-210) DEG C- (165-210) DEG C- (160-200) DEG C- (155-190) DEG C- (150-190) DEG C in sequence.
Preferably, the temperature of each zone of the screw is (175-195) DEG C (175-200) DEG C (170-200) DEG C (165-190) DEG C (160-185) DEG C (155-185) DEG C in sequence.
More preferably, the temperature of each zone of the screw is (180-190) DEG C (175-190) DEG C (170-185) DEG C (165-180) DEG C (165-175) DEG C in sequence.
The rotating speed and the melt blending temperature of the double-screw extruder can influence the blending uniformity and further influence the modification effect of the flame retardant on the polylactic acid, the flame retardant effect on the polylactic acid can be reduced due to the nonuniform blending, and meanwhile, the mechanical property, the spinnability and the post-processing property of the modified compound are reduced due to the stress concentration and the crystallinity caused by the aggregation of the flame retardant. A large number of tests show that the mixing uniformity of the flame retardant and the polylactic acid can be effectively improved by adopting the rotating speed and the temperature for melt blending, so that the flame retardant property of the flame retardant and the polylactic acid is improved.
The invention has the following beneficial effects:
(1) After the flame retardant is added into the PLLA for modification, the crystallinity and spinnability of the finally prepared compound are not influenced, and meanwhile, the compound still has good post-processing property;
(2) The glass transition temperature, the melting point and the thermal decomposition temperature of the PLLA are not influenced by adding the flame retardant into the PLLA,
(3) The flame retardance of the compound prepared by the modified PLLA is greatly improved, the limit oxygen index can reach 35% at most, the ignition time is prolonged, and meanwhile, the flame retardant has the anti-dripping property, can not ignite absorbent cotton, and has the self-extinguishing property;
(4) Compared with unmodified polylactic acid, the mechanical properties of the flame-retardant modified compound, such as breaking strength and breaking elongation, are not obviously reduced, the addition of the modifier does not influence the initial modulus of the compound, in addition, the breaking elongation of the fiber obtained by spinning the flame-retardant modified compound is not obviously changed, and the breaking strength of the fiber still meets the textile requirements.
Examples
The invention is further illustrated by the following specific examples, which are intended to be illustrative only and not limiting to the scope of the invention.
Example 1
PLLA and PEPA were dried in vacuum at 60 ℃ for 12h in a DZF-6050 type vacuum drying oven (Shanghai tree technologies Co., ltd.) at 80 ℃.
After drying, 10g of PEPA and 990g of PLLA were placed in an HK26 twin-screw extruder (Nanjing Keya) for melt blending at a rotation speed of 180r/min, at temperatures of 185 ℃,185 ℃,185 ℃,185 ℃,170 ℃ and 5min in sequence. The resulting product (PLLA/PEPA) was designated PLLA/PEPA1, with a phosphorus content of 1721ppm.
Example 2
The preparation of PLLA/PEPA was carried out in a similar manner to example 1, except that: after drying, 20g of PEPA and 980g of PLLA were melt blended in an HK26 twin-screw extruder (Nanjing Keya) to obtain a product (PLLA/PEPA) named PLLA/PEPA2, wherein the phosphorus content was 3442ppm.
Example 3
The preparation of PLLA/PEPA was carried out in a similar manner to example 1, except that: after drying, 30g of PEPA and 970g of PLLA were melt-blended in an HK26 twin-screw extruder (Nanjing Keya) to give a product (PLLA/PEPA) designated PLLA/PEPA3 with a phosphorus content of 5163ppm.
Example 4
The preparation of PLLA/PEPA was carried out in a similar manner to example 1, except that: after drying, 40g of PEPA and 960g of PLLA were melt blended in an HK26 twin screw extruder (Nanjing Keya) to obtain a product (PLLA/PEPA) designated PLLA/PEPA4 with a phosphorus content of 6884ppm.
Example 5
The preparation of PLLA/PEPA was carried out in a similar manner to example 1, except that: after drying, 50g of PEPA and 950g of PLLA were melt-blended in an HK26 twin-screw extruder (Nanjing Keya) to obtain a product (PLLA/PEPA) named PLLA/PEPA5, wherein the phosphorus content was 8605ppm.
Example 6
The preparation of PLLA/PEPA was carried out in a similar manner to example 1, except that: after drying, 60g of PEPA and 940g of PLLA were melt-blended in an HK26 twin-screw extruder (Nanjing Keya) to give a product (PLLA/PEPA) designated PLLA/PEPA6 with a phosphorus content of 10326ppm.
Example 7
The preparation of PLLA/PEPA was carried out in a similar manner to example 1, except that: after drying, 80g of PEPA and 920g of PLLA were melt-blended in an HK26 twin-screw extruder (Nanjing Keya) to give a product (PLLA/PEPA) designated PLLA/PEPA8 with a phosphorus content of 13768ppm.
Example 8
The preparation of PLLA/PEPA was carried out in a similar manner to example 1, except that: after drying, 100g of PEPA and 900g of PLLA were melt-blended in an HK26 twin-screw extruder (Nanjing Keya) to give a product (PLLA/PEPA) designated PLLA/PEPA10, which had a phosphorus content of 17210ppm.
Example 9
The preparation of PLLA/PEPA was carried out in a similar manner to example 1, except that: after drying, 120g of PEPA and 880g of PLLA were melt-blended in an HK26 twin-screw extruder (Nanjing Keya) to give a product (PLLA/PEPA) designated PLLA/PEPA12 with a phosphorus content of 20652ppm.
Examples 10 to 11
The product PLLA/PEPA3 obtained in example 3 and the product PLLA/PEPA5 obtained in example 5 were spun and drawn separately,
the spinning is carried out by adopting a single screw spinning machine (Dalianhuanlun chemical fiber equipment, inc.), the drafting is carried out by adopting a parallel drafting machine (Shanxi Tongfeng fiber machinery, inc.),
the spinning and drawing process parameters are shown in tables 1 and 2, respectively:
TABLE 1
TABLE 2
Comparative example
Comparative example 1
The preparation was carried out in a similar manner to example 1, with the only difference that PEPA was not added.
Comparative example 2
The Product (PLLA) obtained in comparative example 1 was spun and drawn, the spinning and drawing machines being the same as those used in example 10. The spinning and drawing process parameters are shown in tables 3 and 4, respectively:
TABLE 3
TABLE 4
Comparing the spinning parameters in tables 1 and 3 and the drafting parameters in tables 2 and 4, it can be found that the spinning parameters and the drafting parameters in examples 10 to 11 are the same as those in comparative example 2, which indicates that the addition of PEPA does not affect the spinnability of PLLA, and the flame retardant modified polylactic acid compound obtained after adding PEPA still has good spinnability.
Examples of the experiments
Experimental example 1 thermal Property test
DSC tests were carried out on the products obtained in examples 2 to 6 and comparative example 1 and PEPA by using a Q2000 differential scanning calorimeter of the American TA company, and the DSC test was carried out by using Q2000 of the American TA company, the temperature range was 0 to 200 ℃, the temperature rise rate was 20 ℃/min, and the atmosphere was nitrogen. The DSC curve is shown in FIG. 1.
The products prepared in example 3 and comparative example 1 and PEPA were subjected to a thermogravimetric test using german Netzsch TG 209F1, the specific procedure being: the testing temperature range is room temperature-600 ℃ under the nitrogen atmosphere, and the heating rate is 10 ℃/min. The TGA and DTA curves are shown in FIG. 2 and FIG. 3, respectively.
As can be seen from FIG. 1, the melting point of PEPA is about 210 ℃, the addition of PEPA has little effect on the glass transition temperature of the PLLA/PEPA complex, and the cold crystallization temperature is slightly reduced, which is shown to be easy to crystallize. Meanwhile, PLLA has two almost coincident melting peaks, and after PEPA is added, the compound has two relatively obvious melting peaks, the melting point of the compound is slightly reduced and the melting enthalpy is slightly increased with the increase of the addition amount of PEPA, as shown in Table 5, which indicates that the thermal property and crystallization property of PLLA are not greatly influenced by the addition of PEPA.
TABLE 5
As can be seen from fig. 2, the thermal decomposition temperatures of PEPA and PLLA at 0.5% weight loss were 260 ℃ and 310 ℃, respectively, and the thermal decomposition residue rates at 600 ℃ were 45.3% and 0%, respectively, and the thermal decomposition curve and thermal decomposition temperature of the complex were approximately the same as those of PLLA, and the thermal decomposition residue rate at 600 ℃ was 0.25%. As can be seen from fig. 3, the thermal decomposition reaction of PEPA is an exothermic reaction, and the enthalpy of the exotherm is relatively small, so that the amount of the additive is relatively small, and the change of the enthalpy of the complex is not affected; the thermal decomposition reaction of PLLA and the complex is endothermic reaction, and the peak area of the DTA curve of the complex per unit mass and the baseline is smaller than that of the PLLA, which indicates that PEPA reduces the endothermic quantity of the thermal decomposition reaction of the complex, because PEPA has the function of promoting the polymer to form carbon, and the thermal decomposition reaction is reduced.
Experimental example 2 mechanical Property test
Comparative example 1 and examples 2 to 9 were tested for breaking strength, breaking elongation, modulus, etc. using an INSTRON 5966 universal electronic materials tester, with a nip of 25mm, a tensile rate of 100mm/min, and a test standard GB/T1040-92, the test results of which are shown in Table 6.
TABLE 6
As can be seen from table 6, as the addition amount of PEPA increases, the breaking strength and the breaking elongation of the PLLA/PEPA complex gradually decrease, and when the addition amount of PEPA is 6%, the breaking strength and the breaking elongation of the complex decrease by about 15% and 22%, respectively, and meanwhile, the addition of PEPA makes the initial modulus of the complex higher than that of PLLA, and the addition amount of PEPA has little influence on the initial modulus of the complex.
Experimental example 3 flame retardancy test
(1) Cone calorimetry test
The products obtained in examples 1 to 6 and comparative example 1 were subjected to cone calorimetry and heat transfer using an FTT Standard Corn Calorimeter in EnglandThe rate is 35kW/m 2 Sample size 100X 3mm, test standard ISO 5660-1 2016, 23 ℃, conditioned for 80h under 50% RH conditions.
Among them, the test results of the heat release rates of examples 1 to 3 and comparative example 1 are shown in fig. 4a, the test results of the heat release rates of examples 4 to 6 and comparative example 1 are shown in fig. 4b, the test results of the total heat release amounts of examples 1,2 and 6 and comparative example 1 are shown in fig. 5, the test results of the total smoke release amounts of examples 3 to 6 and comparative example 1 are shown in fig. 6, and the test results of the mass loss rates at the time of combustion of examples 4 to 6 and comparative example 1 are shown in fig. 7.
As can be seen from fig. 4a, 4b and 5, the ignition time of the composite after adding PEPA can be delayed by about 25s, and the ignition time, the peak value of the heat release rate and the total heat release amount do not change obviously with the increasing addition amount of PEPA. As can be seen in FIG. 6, the total smoke release of the complex gradually increased with increasing amounts of PEPA added. In fig. 7, the combustion residue of PLLA is almost 0, while the combustion residue of the composite gradually increases with the increase of the addition amount of PEPA, and when the addition amount is 6%, the combustion residue of the composite is about 3.5%, which is slightly higher than the decomposition residue rate of PEPA, indicating that PEPA has a certain char-promoting effect on the polymer matrix in view of the higher total smoke release amount during combustion.
(2) Limiting oxygen index test
The products obtained in examples 1 to 9 and comparative example 1 were subjected to a limiting oxygen index test and a vertical burning test under specific test conditions of Limiting Oxygen Index (LOI): dynisco oxygen index tester, USA, with a sample size of 100mm 6.5mm 4mm, the test was carried out according to GB/T2406.2-2009, conditioned for 80h at 23 ℃,50% RH.
The specific test conditions for the vertical burn test were: the sample strip size is 100mm multiplied by 13mm multiplied by 4mm by adopting a CZF-3 type horizontal vertical combustion instrument of Nanjing Jiangning analytical instrument, inc., and the test standard GB/T2408-2008 is adjusted for 80h under the condition of 23 ℃ and 50% RH.
In the vertical burning test, t 1 And t 2 The time of the composite after being ignited for 10s twice is respectively shown, and the self-extinguishing performance of the flame-retardant material after being ignited for self-extinguishing is characterized. t is t 1 And t 2 Smaller values of (a) indicate shorter burning time after leaving the fire. The test results are shown in table 7.
TABLE 7
As can be seen from Table 7, when PEPA was added in an amount of 6, the LOI value of the composite increased from 26% to 33%, indicating that the addition of PEPA increased the oxygen demand of the composite during combustion, and increased the ignition difficulty and self-extinguishment of the composite in air. The UL-94 test results show that the self-extinguishing time t1 and t2 of the compound after fire is reduced along with the increase of the PEPA addition amount. When the addition amount of the PEPA is 3%, the vertical burning grade can reach V-0 grade, and molten drops occur in the ignition process, but the absorbent cotton is not ignited. When the PEPA is added in an amount of more than 4 percent, the composite is self-extinguished after being away from fire, and no molten drops exist.
Experimental example 4 scanning Electron microscopy test
The scanning electron microscope test was performed on the residues of the cone calorimetry test of example 2, example 4 and example 6, and the test results are shown as a, b and c in fig. 8, respectively.
As can be seen from fig. 8, when the PEPA addition amount is less than 4%, a mainly flaky carbon layer is formed, the addition amount is 4% as a critical point, both flaky and granulated carbons are present in the residue, and when the addition amount is more than 4%, granulated carbons are mainly formed and aggregated into larger particles during combustion.
Experimental example 5 spinning Properties
The fibers obtained in examples 10 to 11 and comparative example 2 were subjected to mechanical property tests, and the test results are shown in Table 8.
TABLE 8
As can be seen from examples 10-11 and comparative example 2, the addition of PEPA had substantially no effect on the spinning and drawing processes of PLLA, and the composites still had good spinnability and post-processing properties after the addition of PEPA.
As can be seen from Table 8, the addition of PEPA does not substantially affect the elongation at break of PLLA, and the breaking strength of the fiber gradually decreases with the increase of the addition of PEPA, and the breaking strength of the fiber prepared in example 11 is 2.51cN/dtex, and the strength of the fiber still meets the requirements of spinning.
The invention has been described in detail with reference to specific embodiments and illustrative examples, but the description is not intended to limit the invention. Those skilled in the art will appreciate that various equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its embodiments without departing from the spirit and scope of the present invention, which fall within the scope of the present invention. The scope of the invention is defined by the appended claims.
Claims (9)
1. The flame-retardant modified polylactic acid compound is characterized in that the flame-retardant modified polylactic acid compound is obtained by modifying polylactic acid with a phosphate flame retardant;
the phosphate flame retardant is selected from one or more of pentaerythritol phosphate, triethyl phosphate, triphenyl phosphate, tributyl phosphate and triphenyl phosphite.
2. The flame retardant modified polylactic acid compound according to claim 1,
the phosphorus content in the flame-retardant modified polylactic acid compound is 1000-22000 ppm.
3. The flame retardant modified polylactic acid compound according to claim 1,
the flame-retardant modified polylactic acid compound is prepared by melting and blending a phosphate flame retardant and polylactic acid.
4. The flame retardant modified polylactic acid compound according to claim 1,
the blending temperature is 150-210 ℃.
5. The preparation method of the flame-retardant modified polylactic acid compound is characterized in that polylactic acid and a phosphate ester flame retardant are used as raw materials for melt blending.
6. The method according to claim 5,
the mass ratio of the phosphate flame retardant to the polylactic acid is (0.1-20): (80-99.9).
7. The production method according to claim 5,
the blending temperature is 150-210 ℃, and the blending time is 2-10 min.
8. The method of claim 7,
the blending is preferably carried out in a double-screw extruder, and the temperature of each zone of the screw is (170-200) DEG C- (170-210) DEG C- (165-210) DEG C- (160-200) DEG C- (155-190) DEG C- (150-190) DEG C in sequence.
9. The method as claimed in claim 8, wherein the twin-screw extruder is rotated at a speed of 120 to 250r/min.
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| CN111363322A (en) * | 2018-12-26 | 2020-07-03 | 浙江海正生物材料股份有限公司 | Flame-retardant polylactic resin composition and preparation method thereof |
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| CN106147159A (en) * | 2015-04-10 | 2016-11-23 | 马德里高等材料研究院 | A kind of low addition type halogen-free flame retardant polylactic acid composite material and preparation method thereof |
| CN111363322A (en) * | 2018-12-26 | 2020-07-03 | 浙江海正生物材料股份有限公司 | Flame-retardant polylactic resin composition and preparation method thereof |
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