JP6050443B2 - Flame retardant polylactic acid resin composition - Google Patents

Description

  The present invention relates to a flame retardant polylactic acid resin composition in which the amount of smoke generated during combustion is greatly reduced.

  Fossil fuel resources, including oil, will not only be depleted sometime, but will also generate carbon dioxide that causes global warming in the process of using it. Thus, fuel oils obtained from petroleum resources and petrochemical-based polymer materials are being replaced by biomass-based materials. Among such biomass-based materials, polylactic acid (PLA) is attracting attention because it is carbon neutral using plant starch as a raw material, and is expected as an alternative material for petroleum-derived resins. . Polylactic acid is used for disposable items because of its biodegradable properties, but it needs additional flame retardancy to be applied to the electronic equipment field and automotive parts. Smoke generation must also be considered. In fact, when a fire breaks out, it may die because the fire is not extinguished, but it is reported that smoke and toxic gases, which are by-products of combustion, have a greater impact.

  In Patent Document 1, a flame retardant aliphatic polyester resin is produced by copolymerizing a flame retardant and polyester, and then the produced flame retardant polyester resin and polylactic acid resin are mixed at a certain ratio to make it difficult to produce polylactic acid fibers. Gave flammability. However, the compatibility between the polylactic acid and the flame-retardant polyester resin may be low, and the flame-retardant evaluation is based only on LOI (Limited Oxygen Index), and the flame-retardant effect can be accurately understood. I can't.

  Patent Document 2 proposes a flame retardant polylactic acid resin composition containing a flame retardant polyester resin. Similarly, it is possible to accurately evaluate the flame retardant effect by evaluating only the LOI for the flame retardant evaluation. Can not.

  Patent Document 3 proposes a flame-retardant polylactic acid containing a phosphorus-based flame retardant and an anti-drip component, but only flame resistance UL94 was evaluated.

  Patent Document 4 proposes a polylactic acid resin composition containing a thermoplastic resin, a phosphorus-based, nitrogen-based or metal oxide-based flame retardant and a flame retardant aid in addition to polylactic acid, but the flame retardancy is only UL94. Evaluated.

Korean Registered Patent No. 10-1038466 Korean Published Patent No. 10-2011-0032183 Japanese Patent No. 5273646 Japanese Patent No. 5378904

  INDUSTRIAL APPLICABILITY The present invention is useful for manufacturing molded products such as interior / exterior materials and cases of electrical and electronic parts to which existing petrochemical-based flame retardant polyethylene terephthalate (PET) and flame retardant polybutylene terephthalate (PBT) are applied It is intended to provide an environmentally friendly flame retardant polylactic acid resin composition that is greatly reduced in the amount of smoke generated.

  In order to solve the above problems, the present invention provides (A) 85-95% by weight of polylactic acid resin, (B) 3-10% by weight of phosphorus-based flame retardant, and (C) 2-5% by weight of nitrogen-based flame retardant aid. % Flame retardant polylactic acid resin composition is provided.

The flame retardant polylactic acid resin composition according to the present invention has a feature that the amount of smoke generated is greatly reduced, and at the same time, is very excellent in flame retardancy, so it is applied to interior and exterior materials and cases of electrical and electronic parts. it can.
In terms of environmental aspects, the inclusion of polylactic acid, an environmentally friendly material, has the effect of reducing carbon dioxide when replacing petrochemical-based plastics.

The flame-retardant polylactic acid resin composition of the present invention comprises (A) 85-95% by weight of a polylactic acid resin, (B) 3-10% by weight of a phosphorus-based flame retardant, and (C) 2-5 of a nitrogen-based flame retardant aid. It is characterized by containing weight%.
Hereinafter, each component contained in the flame retardant polylactic acid resin composition according to an embodiment of the present invention will be described in more detail.

(A) Polylactic acid (PLA)
Polylactic acid is a typical aliphatic polyester-based resin, a biodegradable polymer synthesized using monomers obtained from 100% renewable resources such as corn and potato starch.

  The polylactic acid is produced by polymerization of lactic acid, which is a monomer. Lactic acid can be produced by chemical synthesis and cereal resource fermentation. Lactic acid chemically synthesized from fossil raw materials is made from a racemic mixture in which L-type and D-type lactic acid are mixed by 50% by weight, whereas in the method by starch fermentation, 99.5% by weight or more of L- Since type lactic acid is obtained, the production method by fermentation of food resources is preferred. Currently, lactic acid is the cheapest and is produced using glucose obtained from abundant corn starch.

  In the present invention, poly-L-lactic acid, poly-D-lactic acid, poly- (D, L) -lactic acid, or a combination thereof can be used as the polylactic acid resin. The polylactic acid is preferably one having a high optical purity of lactic acid. Since the higher the optical purity, the higher the heat resistance and the crystallization speed, polylactic acid having an optical purity of 95% or more is preferable.

  The molecular weight of the polylactic acid used in the present invention is not particularly limited in terms of molecular weight and molecular weight distribution as long as injection molding is possible, but the weight average molecular weight is preferably 50,000 to 400,000 g / mol, and the machine of the molded product In order to further increase the mechanical strength, 100,000 to 400,000 g / mol is more preferable.

  In the flame-retardant polylactic acid resin composition of the present invention, the content of the polylactic acid is preferably 85 to 95% by weight based on the weight of the entire resin composition. When the polylactic acid resin is included in the above range, a polylactic acid resin composition having an excellent balance between workability and mechanical properties can be ensured.

(B) Phosphorus flame retardant In general, phosphorus flame retardants produce phosphoric acid, metaphosphoric acid, and polymetaphosphoric acid by thermal decomposition, and the char ( It exhibits flame retardancy due to the blocking effect of char).

  Flame retardants can be classified into additive and reactive flame retardants according to the method of imparting flame retardancy. The additive type flame retardant is added as an additive during the compounding process and simply mixed, and the reactive type flame retardant is introduced by introducing a monomer capable of imparting flame retardancy to the main chain of the polymer compound. A flame retardant substance is produced by chemically bonding a flame retardant substance to the terminal or side chain of the polymer compound by introducing a reactive biogroup into the polymer compound. .

In the present invention, both the additive type and the reactive type can be used as the phosphorus-based flame retardant. Examples of the additive-type phosphorus-based flame retardant include phosphate ester or phosphate, and a representative example thereof is resorcinol bis (diphenyl) phosphate (resorcinol bis (diphenyl phosphate), RDP). As the reactive phosphorus flame retardant, a compound represented by the following chemical formula 1 can be used. In the following chemical formula 1, R ₁ is an allyl group such as phenyl, benzyl, tolyl, xylyl, and R ₂ is an alkyl group having 1 to 10 carbon atoms. is there. A typical reactive phosphorus flame retardant is 3- (hydroxyphenylphosphinyl) propanoic acid.

  In the flame retardant polylactic acid resin composition of the present invention, the content of the phosphorus flame retardant is preferably 3 to 10% by weight based on the weight of the entire resin composition. If the content of the phosphorus flame retardant is less than 3% by weight, the effect of the flame retardant is inferior, and if it exceeds 10% by weight, it is effective in terms of flame retardancy, but rather the amount of smoke generated is too low. Therefore, the mechanical properties are deteriorated, which is not preferable in terms of economy.

(C) Nitrogen-based flame retardant aids Generally, flame retardant aids are used to maximize flame retardancy while reducing the content of flame retardants.
The following nitrogen-based flame retardant aids are substances that cause a synergistic effect with phosphorus-based flame retardants and improve flame retardancy. The nitrogen flame retardant aid is selected from nitrogen compounds such as melamine, tris (hydroxyethyl) isocyanurate (THEIC), melamine phosphate (MP), melamine polyphosphate (MPP), melamine cyanurate (MC), etc. 1 type or more is mentioned.

  In the flame retardant polylactic acid resin composition of the present invention, the content of the nitrogen-based flame retardant aid is preferably 2 to 5% by weight based on the weight of the entire resin composition. If the content of the nitrogen-based flame retardant auxiliary is less than 2% by weight, the synergistic effect with the flame retardant is inferior, and if it exceeds 5% by weight, the mechanical properties of the polylactic acid resin composition are inferior.

  In addition, the composition of the present invention may further include an inorganic filler in order to enhance mechanical properties. A typical inorganic filler includes glass fiber, and the glass fiber is an inorganic filler added to improve mechanical properties such as heat resistance, tensile strength and flexural modulus of the polylactic acid resin composition. In particular, the glass fibers are preferably in a chopped form, and more particularly in the form of chopped strands having a diameter of 10 to 15 μm and a length of 3 to 5 mm.

  The glass fibers can be treated with glass fiber treating agents during fiber production or in a post-treatment process. Examples of the glass fiber treating agents include lubricants and coupling agents. The lubricant is mainly used for forming good strands during glass fiber production. The coupling agent is for increasing the adhesive force between the glass fiber and the polylactic acid resin. When the coupling agent is appropriately selected in consideration of the types of the polylactic acid resin and the glass fiber, the polylactic acid is used. Excellent physical properties can be imparted to the resin composition. As the coupling agent, it is preferable to use a silane-based material having an organic functional group such as a vinyl group, an epoxy group, a mercaptan group, or an amine group.

  In addition, the composition of the present invention may further contain an additive depending on required properties. Examples of the additive include a heat stabilizer, an antioxidant, a light stabilizer, a release agent, a dye, a pigment, a colorant, a nucleating agent, a plasticizer, an impact reinforcing agent, a hydrolysis inhibitor, a stabilizer, and a lubricant. More than seeds are possible.

  The present invention can be more specifically understood by way of examples, and the following examples are merely examples for illustrating the present invention and do not limit the protection scope of the present invention.

Each component of the flame retardant polylactic acid resin composition used in Examples and Comparative Examples of the present invention is as follows.
(A) Polylactic acid 4032D manufactured by NatureWorks LLC of America was used.
(B-1) Additive Phosphorus Flame Retardant Reofos RDP (resorcinol bis (diphenyl) phosphate) manufactured by Chemtura, USA was used.
(B-2) Reactive Phosphorus Flame Retardant Hiretar 205 ((3-hydroxyphenylporphinyl) propanoic acid), which is a reactive phosphorus flame retardant manufactured by Korea Coron Life Science, was used.
(C) Nitrogen-based flame retardant auxiliary Melamine produced by Junsei in Japan was used.
(D) Polyethylene terephthalate (PET)
SKY-PET BR manufactured by SK chemicals of Korea was used.
(E) Polybutylene terephthalate (PBT)
KP211 manufactured by Korea Kolon Plastic was used.

Examples 1-2 and Comparative Examples 1-9
Each component was mixed in the content shown in Table 1 to produce a resin composition, and then the mixture was extruded in a temperature range of 160 to 230 ° C. with a biaxial extruder with L / D 40 and a diameter of 30 mm. The product was produced in pellet form. In Table 1 below, the content unit of each component is% by weight. After the pellets produced by the above method were dried at 80 ° C. for 4 hours, a flame retardant evaluation specimen was produced using an auto press. The flame retardant evaluation was measured by the following method, and the results are shown in Table 2 below.

Flame retardancy evaluation 1) Flame retardancy: Based on UL94, flame retardancy was evaluated with a specimen having a thickness of 3 mm.
2) Total heat release (THR, Total Heat Release): Based on ISO 5660, evaluation was performed using a cone calorimeter (FESTEC) equipment.
3) Total smoke production (TSP, Total Smoke Production): Based on ISO 5660, evaluation was performed using an equipment of cone calorimeter (FESTEC).

ISO 5660 (Reaction-to-fire tests: Heat release, smoke production and mass loss rate) stipulates a test method for evaluating the dynamic smoke generation rate of a flat specimen exposed to radiant heat. This test method is generally based on the fact that the intensity of light transmitted through the combustion products decreases with the exponential product with distance (Bouguer's law). The test body used for the test is burned under atmospheric conditions while receiving external radiant heat within a predetermined range of 0 to 100 kW / m ^2, and measured for light attenuation, exhaust gas flow rate, and mass reduction rate of the test body. Dimming is measured by the ratio of the intensity of light transmitted through the smoke in the exhaust duct. This ratio is used to calculate an attenuation coefficient according to Bouguer's law. The test results show the total smoke generation rate and smoke generation rate normalized from the surface area of the exposed specimen. The smoke generation rate is calculated by the product of the attenuation coefficient and the optimum flow rate of smoke in the exhaust duct. The total amount of smoke generated is obtained from the cumulative amount of time in consideration of the smoke generation rate. The total smoke generation amount and smoke generation rate can be calculated through the following equations.

S = _P cumulative amount _P of _{s s} = k × _{V s}
k = ln (l ₀ / l) / L
V _s = m _e × T _s /(12.2×10 ³ × M)

S: Total smoke generation [m ² ]
P _s : Smoke generation rate [m ² / s]
k: damping coefficient [m ⁻¹ ]
ln: Natural log l ₀ : Light intensity when there is no smoke [W / m ² ]
l: Reduced light intensity [W / m ² ]
L: Path of light passing through smoke [m]
V _s : Volume flow rate of smoke at the measurement fulcrum [m ³ / s]
m _e : Mass flow rate measured at the orifice [kg / s]
T _s : Smoke temperature at the measurement fulcrum [K]
M: Molecular weight of air flowing through the exhaust duct, 0.029 [kg / mol]

  As can be seen from the results of Examples and Comparative Examples shown in Tables 1 and 2, the flame retardant polylactic acid resin compositions of Examples 1 and 2 having the composition according to the present invention are 100% by weight of polylactic acid. It can be confirmed that not only the amount of smoke generated is greatly reduced as compared with Comparative Example 1 used, but also excellent in flame retardancy. That is, in Example 1 and Example 2, it can be seen that V-0 flame retardancy and total smoke generation can be greatly reduced by the phosphorus-based flame retardant and flame retardant aid used in the present invention.

  From the results of Comparative Example 1 using 100% by weight of polylactic acid, Comparative Example 6 using 100% by weight of polyethylene terephthalate, and Comparative Example 8 using 100% by weight of polybutylene terephthalate, it is completely burned when there is no flame retardant. It can be seen that the total heat release and smoke generation are high.

  From the results of Comparative Example 2, it can be seen that when the content of the additive-type phosphorus flame retardant is 1% by weight, it is completely burned.

  From the results of Comparative Example 3, it can be seen that when the content of the reactive phosphorus flame retardant is 2% by weight, V-2 flame retardancy appears, but the total amount of smoke generated does not decrease significantly.

  From the results of Comparative Example 4 and Comparative Example 5, when the contents of the additive-type phosphorus-based flame retardant and the reactive-type phosphorus-based flame retardant are 20% by weight, V-1 and V-0 flame retardancy are obtained. It can be seen that the total smoke generation does not decrease greatly.

  Comparative Example 7 and Comparative Example 9 are cases where flame retardant polyethylene terephthalate and flame retardant polybutylene terephthalate are used, respectively, and it can be seen that the effect of reducing the total smoke generation amount is not large.

  Overall, the flame retardant polylactic acid resin composition of the present invention has a feature that the amount of smoke generated is greatly reduced, and at the same time, the flame retardancy is very excellent. It can be usefully used for manufacturing molded articles such as interior and exterior materials and cases of electrical and electronic parts to which polyethylene terephthalate (PET) and flame-retardant polybutylene terephthalate (PBT) are applied.

Claims (9)

(A) 85-95% by weight of polylactic acid resin;
(B) 3-10 wt% phosphorus flame retardant; and
(C) 2-5% by weight of a nitrogen-based flame retardant aid;
The phosphorus-based flame retardant is a reactive phosphorus-based flame retardant represented by the following chemical formula 1, the flame retardant grade is V-0, and the total smoke generation amount is 2.0 m ² (3 mm thick specimen) Standard) The flame retardant polylactic acid resin composition is :

Where R ₁ is phenyl, benzyl, tolyl or xylyl;
R ₂ is an alkyl group having 1 to 10 carbon atoms.   The polylactic acid is poly-L-lactic acid, poly-D-lactic acid, poly- (D, L) -lactic acid, or a combination thereof, optical purity is 95% or more, and weight average molecular weight is 50,000. The flame retardant polylactic acid resin composition according to claim 1, wherein the composition is ˜400,000 g / mol. The reactive phosphorus flame retardant 3- (hydroxyphenyl phosphonyl) flame retardant polylactic acid resin composition of claim 1, wherein the propane acid.   The flame retardant according to claim 1, wherein the nitrogen-based flame retardant aid is one or more selected from melamine, tris (hydroxyethyl) isocyanurate, melamine phosphate, melamine polyphosphate and melamine cyanurate. Polylactic acid resin composition.   The flame retardant polylactic acid resin composition according to claim 1, wherein the composition further comprises glass fiber. 6. The flame retardant polylactic acid resin composition according to claim 5, wherein the glass fiber has a diameter of 10 to 15 [mu] m, a length of 3 to 5 mm, and a chopped strand form. 6. The flame retardant polylactic acid resin composition according to claim 5, wherein the glass fiber is treated with a silane-based material having an organic functional group selected from a vinyl group, an epoxy group, a mercaptan group, and an amine group. An interior / exterior material injection product of an electrical / electronic component comprising the flame retardant polylactic acid resin composition according to any one of claims 1 to 7.   A case injection product comprising the flame retardant polylactic acid resin composition according to any one of claims 1 to 7.