Polyamide resin, polyamide resin composition containing same, preparation method therefor, and molded product including same

Abstract

The polyamide resin of the present invention is a polymer of a monomer mixture including a dicarboxylic acid and an amine-based compound, wherein the amine-based compound comprises diamine and triamine and a branching rate measured using .sup.1H-NMR is approximately 1% to approximately 8%.

Claims

1. A polyamide resin composition comprising: a polyamide resin which is a polymer of a monomer mixture comprising a dicarboxylic acid and an amine compound comprising a diamine and a triamine, wherein the polyamide resin has a branch rate of about 1% to about 8%, as measured using .sup.1H-NMR; and about 10 to about 50 parts by weight of a fiber-reinforcing agent relative to 3 parts by weight of the polyamide resin, wherein the polyamide resin composition has a notched Izod impact strength of about 8.0 kgf.Math.cm/cm to about 12 kgf.Math.cm/cm, as measured on a specimen in accordance with ASTM D256.

2. The polyamide resin composition according to claim 1, wherein the polyamide resin composition has a 1,000-hour tensile strength retention rate of about 80% or more, as measured on a specimen at 170 C. in accordance with ASTM D638.

3. The polyamide resin composition according to claim 1, further comprising: a flame retardant, a surfactant, a nucleating agent, a coupling agent, a filler, a plasticizer, an impact modifier, a lubricant, an antibiotic agent, a release agent, a heat stabilizer, an antioxidant, a photostabilizer, a compatibilizer, an inorganic additive, a colorant, a lubricating agent, an antistatic agent, a pigment, a dye, and/or a flame proofing agent.

4. The polyamide resin composition according to claim 1, wherein the triamine is represented by Formula (1): ##STR00005## wherein R.sub.1 and R.sub.2 are each independently a C.sub.1 to C.sub.15 alkylene group, a C.sub.2 to C.sub.15 branched alkylene group, or a C.sub.3 to C.sub.15 cycloalkylene group.

5. The polyamide resin composition according to claim 1, wherein the dicarboxylic acid comprises a C.sub.8 to C.sub.20 aromatic dicarboxylic acid and/or a C.sub.3 to C.sub.20 aliphatic dicarboxylic acid.

6. The polyamide resin composition according to claim 1, wherein the diamine comprises a C.sub.6 to C.sub.20 aromatic diamine and/or a C.sub.2 to C.sub.20 aliphatic diamine.

7. The polyamide resin composition according to claim 1, wherein the triamine is present in an amount of about 1 mol % to about 8 mol % based on 100 mol % of the amine compound.

8. The polyamide resin composition according to claim 1, wherein the dicarboxylic acid and the amine compound are present in a mole ratio of about 1:0.98 to about 1:1.15.

9. The polyamide resin composition according to claim 1, wherein the polyamide resin has a difference of about 50 C. or more between melting temperature (Tm) and crystallization temperature (Tc) thereof.

10. A molded product formed from a polyamide resin composition comprising: a polyamide resin which is a polymer of a monomer mixture comprising a dicarboxylic acid and an amine compound comprising a diamine and a triamine, wherein the polyamide resin has a branch rate of about 1% to about 8%, as measured using .sup.1H-NMR; and about 10 to about 50 parts by weight of a fiber-reinforcing agent relative to 3 parts by weight of the polyamide resin, wherein the polyamide resin composition has a notched Izod impact strength of about 8.0 kgf.Math.cm/cm to about 12 kgf.Math.cm/cm, as measured on a specimen in accordance with ASTM D256.

Description

EXAMPLES

(1) Preparation of Polyamide Resin

(2) (A) Dicarboxylic Acid

(3) (a1) Adipic acid: Adipic acid produced by Aldrich was used.

(4) (a2) Terephthalic acid: Terephthalic acid produced by Aldrich was used.

(5) (B) Diamine

(6) (b1) m-xylene diamine: m-xylene diamine produced by TCI Co., Ltd. was used.

(7) (b2) 1,6-hexamethylenediamine: 1,6-hexamethylenediamine produced by Aldrich was used.

(8) (C) Triamine

(9) Bis(hexamethylene)triamine (BHMT): BHMT produced by Aldrich was used.

Example 1

(10) A monomer mixture comprising 0.300 moles (43.8 g) of adipic acid as a dicarboxylic acid, 0.300 moles (40.9 g) of m-xylene diamine as a diamine and 0.003 moles (0.7 g) of bis-hexamethylene triamine (BHMT) as a triamine, 0.006 moles (0.4 g) of acetic acid as an end-capping agent, 0.1 g of sodium hypophosphate as a catalyst, and 29 ml of distilled water were placed in a 1 L autoclave, which in turn was charged with nitrogen gas. After the components were stirred at 130 C. for 60 minutes and the temperature was raised to 210 C. for 1 hour, reaction was performed for 1 hour under a maintaining pressure of 13 kgf/cm.sup.2 and the resulting material was separated into water and a prepolymer through flash(leaching). The separated polyamide prepolymer (inherent viscosity []=0.25 dL/g) was put into a tumbler-shaped reactor, followed by solid state polymerization at 190 C. for 5 hours. Thereafter, the resulting material was slowly cooled to room temperature, thereby obtaining a copolymerized polyamide resin (hereinafter, a-1 resin).

Example 2

(11) A polyamide resin (hereinafter, a-2 resin) was prepared in the same manner as in Example 1 except that 0.288 moles (39.2 g) of m-xylene diamine was used as the diamine and 0.015 moles (3.2 g) of bis-hexamethylene triamine (BHMT) was used as the triamine.

Example 3

(12) A polyamide resin (hereinafter, a-3 resin) was prepared in the same manner as in Example 1 except that 0.135 moles (19.7 g) of adipic acid and 0.165 moles (27.4 g) of terephthalic acid were used as the dicarboxylic acid and 0.300 moles (34.9 g) of 1,6-hexamethylenediamine) was used as the diamine.

Example 4

(13) A polyamide resin (hereinafter, a-4 resin) was prepared in the same manner as in Example 3 except that 0.288 moles (33.5 g) of 1,6-hexamethylenediamine was used as the diamine and 0.015 moles (3.3 g) of bis-hexamethylene triamine (BHMT) was used as the triamine.

Comparative Example 1

(14) A polyamide resin (hereinafter, b-1 resin) was prepared in the same manner as in Example 1 except that 0.303 moles (41.3 g) of m-xylene diamine was used as the diamine and the triamine was not used.

Comparative Example 2

(15) A polyamide resin (hereinafter, b-2 resin) was prepared in the same manner as in Example 1 except that 0.301 moles (41.1 g) of m-xylene diamine was used as the diamine and 0.0015 moles (0.3 g) of bis-hexamethylene triamine (BHMT) was used as the triamine.

Comparative Example 3

(16) A polyamide resin (hereinafter, b-3 resin) was prepared in the same manner as in Example 3 except that 0.303 moles (35.2 g) of 1,6-hexamethylenediamine was used as the diamine and the triamine was not used.

Comparative Example 4

(17) A polyamide resin (hereinafter, b-4 resin) was prepared in the same manner as in Example 3 except that 0.301 moles (35.0 g) of 1,6-hexamethylenediamine was used as the diamine and 0.0015 moles (0.3 g) of bis-hexamethylene triamine (BHMT) was used as the triamine.

Comparative Example 5

(18) A polyamide resin (hereinafter, b-5 resin) was prepared in the same manner as in Example 3 except that 0.273 moles (31.7 g) of 1,6-hexamethylenediamine was used as the diamine and 0.030 moles (6.5 g) of bis-hexamethylene triamine (BHMT) was used as the triamine.

(19) Mol % of each component used as the dicarboxylic acid (A) and the amine compounds ((B), (C)) in Examples 1 to 4 and Comparative Examples 1 to 5, the mole ratio of the amine compound to the dicarboxylic acid (amine compound mole)/(dicarboxylic acid mole), and the melting temperature ( C.), glass transition temperature ( C.), inherent viscosity (dL/g) and GPC PDI (gel permeation chromatography polydispersity index) of the polyamide resin are shown in Table 1.

(20) TABLE-US-00001 TABLE 1 Example Comparative Example 1 2 3 4 1 2 3 4 5 (A) (a1) 100 100 45 45 100 100 45 45 45 (a2) 55 55 55 55 55 Amine compound (B) (b1) 99 95 100 99.5 (b2) 99 95 100 99.5 90 (C) 1.0 5.0 1.0 5.0 0.5 0.5 10 Mole ratio of amine 1.01 1.01 1.01 1.01 1.01 1.01 1.01 1.01 1.01 compound to dicarboxylic acid Melting temperature ( C.) 220 210 300 298 230 225 307 302 295 Glass transition 92 95 94 95 88 90 91 92 96 temperature ( C.) Inherent viscosity (dL/g) 1.5 2.0 1.6 2.5 0.85 1.0 0.90 1.1 Gel GPC PDI (Mw/Mn) 3.5 5.0 4.8 5.5 2.2 2.5 3.0 4.5 Branch rate (%) 1.2 5.2 1.0 4.9 0.1 0.6 0.2 0.5 14

(21) Polyamide Resin Composition

Examples 5 to 8 and Comparative Examples 6 to 11

(22) Each polyamide resin composition was prepared by mixing the following first polyamide resin, the following second polyamide resin, the following heat stabilizer, the following fiber-reinforcing agent, and the following impact modifier in amounts (parts by weight) as listed in Table 2, followed by extrusion using a twin-axis extruder (L/D=37:1) at 260 C. for Examples 5 to 6, Comparative Examples 6 to 7 and Comparative Example 11, and at 310 C. for Examples 7 and 8 and Comparative Examples 8 to 10.

(23) First polyamide resin: Each of the polyamide resins prepared in Examples 1 to 4 and Comparative Examples 1 to 5 was used in amounts as listed in Table 2.

(24) Second polyamide resin: The polyamide resin prepared in Comparative Example 1 was applied to Examples 5 and 6, Comparative Examples 6 and 7, and Comparative Example 11, and the polyamide resin prepared in Comparative Example 3 was applied to Examples 7 to 8 and Comparative Examples 8 to 10.

(25) (D) Heat stabilizer: Bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite produced by ASAHI DENKA was used.

(26) (E) Fiber-reinforcing agent: EC10 3MM 910 (SAINT-GOBAIN) was used.

(27) (F) Impact modifier: Maleic anhydride grafted ethylene-propylene rubber produced by EXXON was used.

(28) Impact strength (kgf.Math.cm/cm), tensile strength retention rate (%) and surface gloss (at 60) of each of the polyamide resin compositions prepared in Examples 5 to 8 and Comparative Examples 6 to 11 were measured and results are shown in Table 2.

(29) TABLE-US-00002 TABLE 2 Example Comparative Example 5 6 7 8 6 7 8 9 10 11 First a-1 3 polyamide resin a-2 3 a-3 3 a-4 3 b-1 3 b-2 3 b-3 3 b-4 3 b-5 3 Second b-1 66.7 66.7 66.7 66.7 66.7 polyamide resin b-3 66.7 66.7 66.7 66.7 66.7 (D) 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 (E) 30 30 30 30 30 30 30 30 30 30 (F) 3 Impact strength 8.0 9.0 8.2 10.2 6.8 6.9 7.5 7.8 12.9 10.1 (kgf .Math. cm/cm) Tensile strength 81 82 82 83 80 78 85 83 84 72 retention rate (%) Surface gloss (60) 45 25 22 20 58 56 45 40 25 59

(30) (In Table 2, the content is represented in parts by weight.)

(31) In Table 2, it can be seen that the polyamide resin compositions of Examples including the triamine within the range according to the present invention exhibited good properties in terms of impact strength, tensile strength retention rate and extinction effect.

(32) On the contrary, it can be seen that the polyamide resin compositions of Comparative Examples including no triamine or the triamine out of the range according to the present invention exhibited deterioration in properties in terms of impact strength, tensile strength retention rate or extinction effect. Moreover, the polyamide resin compositions of Comparative Example 11 comprising the impact modifier instead of the triamine exhibited deterioration in tensile strength retention rate and extinction effect.

(33) Evaluation of Properties

(34) (1) Melting temperature (Tm), crystallization temperature (Tc) and glass transition temperature (Tg) (unit: C.): Each temperature was measured using a different scanning calorimeter (DSC). As the DSC, a Q20 (TA instruments) was used and measurement was performed in a nitrogen atmosphere under conditions of 30 C. to 350 C. at a temperature increase temperature of 10 C./min, and a cooling speed of 10 C./min.

(35) (2) Inherent viscosity (IVO, unit: dL/g): A polyamide resin was dissolved to a concentration of 0.5 g/dL in a 98% sulfuric acid solution and inherent viscosity was measured at 25 C. using an Ubbelohde viscometer.

(36) (3) GPC polydispersity index (PDI): PDI was analyzed using hexafluoroisopropanol under conditions of 1 ml/min and 40 C. in a PMMA standard.

(37) (4) Branch rate: Branch rate was measured by 600 MHz 1H-NMR (BRUKER Inc.) after dissolving a sample to 5 w/v % using trifluoroacetic acid-d (TFA-d) as a solvent. The branch rate was quantified based on a chemical shift and a variation of height at main peak after addition of a triamine with reference to a standard sample not containing the triamine.

(38) (5) Izod impact strength (unit: kgf.Math.cm/cm): Impact strength was measured on a thick notched Izod specimen in accordance with ASTM D256.

(39) (6) Tensile strength retention rate (long-term thermal resistance stability, unit: %): Initial tensile strength (unit: kgf/cm.sup.2) was measured on a sample prepared by injection molding of each of the resin compositions of Examples 5 to 8 and Comparative Example 5 to 11 to which the glass fibers were added. Injection molding was performed at 260 C. to 330 C. depending upon melting temperature. Thereafter, each sample was left at 170 C. in a constant temperature oven for 1,000 hours and was measured as to tensile strength. Then, the tensile strength retention rate was calculated by comparing the initial tensile strength with the tensile strength after 1,000 hours. A higher retention rate indicates better long-term thermal resistance stability.

(40) (7) Surface gloss (unit: %): Surface gloss was measured at an angle of 60 using a BYK-Gardner gloss meter in accordance with ASTM D523.

(41) Although some embodiments have been described above, it should be understood that the present invention is not limited to these embodiments, and that various modifications, changes, alterations and variations can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, it should be understood that the above embodiments are provided for illustration only and are not to be construed in any way as limiting the present invention.