KR20160146063A - Polyamide resin composition with high fluidity - Google Patents

Abstract

The present invention relates to a polyamide resin composition which comprises 0.1 to 0.5 parts by weight of an antioxidant, with respect to 100 parts by weight of a polyamide resin mixed with a first polyamide and a second polyamide modified with an aromatic reactive compound, in a weight ratio of 9 : 1 to 5 : 5 and has a melting flow index of 10 g/min or more. The polyamide resin produced by using the polyamide resin composition according to the present invention can preserve the impregnating rate and the length of a glass fiber due to high flowability, and can increase mechanical properties including the impact strength, tensile strength, flexural strength, and flexural elastic modulus of a composite material.

Description

[0001] The present invention relates to a polyamide resin composition having high fluidity,

TECHNICAL FIELD The present invention relates to a polyamide resin composition, and more particularly, to a polyamide resin composition capable of increasing the rate of infiltration of glass fibers because of its excellent flowability.

GHG emission regulations and fuel efficiency regulations are being strengthened around the world. In order to improve the fuel efficiency of transport equipment, there is a need for lightweight materials through the development of metal replacement parts. Existing automobile parts are made of steel and have good strength but they are heavy. Magnesium and aluminum, which are alternative materials, are good in light weight, but lack competitiveness in price.

Advanced companies in Korea and abroad are working on various materials with thermoplastic resin in order to obtain high light weighting and price competitiveness and to compensate the shortcomings of the process. Automotive parts are required to have high rigidity and durability. However, in the case of composite materials using thermoplastic resin, durability test is required because they do not have rigidity as much as steel.

The thermoplastic resin has been improved in mechanical stiffness and heat resistance by adding an inorganic reinforcing agent such as glass fiber, and it has been commercialized in structural materials and automobile interior-exterior materials. However, in some parts such as vehicle engines, there are limitations in application due to problems of physical properties and heat resistance. Examples of the thermoplastic resin used in the vehicle include polyamide, polyethylene terephthalate, polybutylene terephthalate, and polyoxymethylene. Of these, polyamide has the lowest specific gravity, which is advantageous for light weight, excellent in physical properties, There are advantages.

The polyamide has good formability and can be improved in physical properties by using glass fiber, but it does not exhibit sufficient strength to replace conventional steel. In order to maximize the physical properties of the composite material, the properties of the polyamide and the glass fiber should be improved. As a method applicable to this method, a method of maximizing the polyamide impregnation rate in the glass fiber, a method of preserving the length of the glass fiber , There is a method of maximizing the physical properties of the polyamide itself.

Korean Patent No. 10-0977178 discloses a flame-retardant polyamide resin composition comprising a polyamide resin, a rubber-modified aromatic vinyl resin, a brominated diphenylethane mixture, and antimony oxide. However, There is a problem that the physical properties are deteriorated.

Korean Patent Registration No. 10-0977178

An object of the present invention is to provide a polyamide resin composition which can increase the rate of infiltration of glass fiber while maintaining strength. Specifically, it is an object of the present invention to improve the physical properties of a composite material while maintaining the length of the glass fiber by increasing the infiltration rate of the glass fiber by modifying the polyamide to a low viscosity.

In order to achieve the above object, the present invention provides a polyamide resin composition comprising 100 parts by weight of a polyamide resin having a weight ratio of a first polyamide and an aromatic reactive compound modified to 9: 1 to 5: 5 by weight, 0.5 parts by weight, and a melt flow index of 10 g / min or more.

The first polyamide of the present invention may have a sulfuric acid relative viscosity of 2.5 to 3.0 and the second polyamide may have a sulfuric acid relative viscosity of 1.8 to 2.0.

The second polyamide of the present invention may be formed by reacting a third polyamide having a sulfuric acid relative viscosity of 2.0 to 2.5 with 1 to 5 parts by weight of an aromatic reactive compound and the aromatic reactive compound is selected from an aromatic carboxylic acid compound or an aromatic amine compound Lt; / RTI >

The aromatic carboxylic acid compound of the present invention may be selected from the group consisting of isophthalic acid, terephthalic acid, naphthalene dicarboxylic acid, benzoic acid, salicylic acid, trimellitic acid ), Vanillic acid, and combinations thereof. The aromatic amine compound may be at least one selected from the group consisting of 1,4-phenylenediamine, 1,3-phenylene Examples thereof include 1,3-phenylenediamine, 2,5-diaminotoluene, 4-methoxy-m-phenylenediamine, 1,3,5-benzenetriamine (1,3,5-benzenetriamine), and combinations thereof.

The antioxidant of the present invention is an antioxidant mixed with a primary antioxidant and a secondary antioxidant. The primary antioxidant is N, N'-hexane-1,6-diylbis (3- (3,5- butyl-4-hydroxyphenylpropionamide), N, N'-di-2-butyl-1,4-phenylenediamine, 2,6- 2,6-di-tert-butylphenol, 2,2'-Ethylidenebis (4,6-di-t-butylphenol), 2,2'-Methylenebis -Butylidenebis (2-t-butyl-5-methylphenol), 4,4'-Thiobis (2-t-butyl-5-methylphenol), Octadecyl 3- (3 ', 5'- -hydroxyphenyl) propionate, and combinations thereof. The secondary antioxidant may be at least one selected from the group consisting of Tris (2,4-di-tert-butylphenyl) phosphite, Triphenyl phosphite, Tris (nonylphenyl) isodecyl phosphite, diphenyl-isooctyl-phosphite, bis (2,6-di-tert-butyl-4-methyphenyl) penta erythritol-diphosphite and combinations thereof.

(A) mixing 1 to 5 parts by weight of an aromatic reactive compound with 100 parts by weight of a third polyamide to modify the second polyamide;

(b) mixing the first polyamide and the second polyamide in a weight ratio of from 9: 1 to 5: 5;

(c) mixing 0.1 to 0.5 parts by weight of an antioxidant with the polyamide resin mixed in the step (a); And

(d) mixing in a twin-screw extruder heated to 250 to 290 占 폚 at a rotating speed of 200 to 400 rpm.

The present invention provides a plastic molded article produced using the polyamide resin composition.

The polyamide resin prepared by using the polyamide resin composition according to the present invention has a high flowability and thus can preserve the infiltration rate of the glass fiber and the length of the glass fiber. At the same time, the impact strength, tensile strength, The mechanical properties including the elastic modulus can be improved.

The present invention relates to a polyamide resin composition comprising 0.1 to 0.5 parts by weight of an antioxidant, based on 100 parts by weight of a polyamide resin mixed with a first polyamide and a second polyamide modified with an aromatic reactive compound in a weight ratio of 9: 1 to 5: 5, And a melt flow index of 10 g / min or more.

 Hereinafter, the constituent components and the content of the present invention will be described in detail.

(1) Polyamide

The polyamide resin is an essential material of the present invention and has excellent mechanical properties and thermal resistance properties such as tensile strength, bending strength, impact strength, heat resistance, chemical resistance and moldability and is widely used in various fields such as automobile, .

The polyamide resin used in the present invention is not particularly limited, and aromatic polyamide, aliphatic polyamide, or aromatic and aliphatic polyamide may be used. In the present invention, an aliphatic polyamide can be preferably used.

The aliphatic polyamide having a weight average molecular weight of 10,000 to 200,000 g / mol can improve the mechanical properties and chemical stability of the polyamide resin composition within the above range. The aliphatic polyamide may be synthesized by a method well known in the art or selected commercially.

Polyamide resins are classified into low viscosity, medium viscosity and high viscosity according to molecular weight. The higher the molecular weight, the lower the viscosity and the better the physical properties. On the contrary, the lower the molecular weight, the lower the viscosity and the better the physical properties are.

(1-1) First polyamide

The first polyamide may be a polyamide having a sulfuric acid relative viscosity of 2.5 to 3.0 adjusted to the molecular weight of the polyamide. Within this range, excellent effects can be obtained in improving tensile strength, impact strength, and mechanical properties.

The relative viscosity of sulfuric acid is determined by the sulfuric acid viscosity method according to ISO 307, and is a ratio (a / b) of the solution viscosity (a) to the solvent viscosity (b) .

(1-2) Second polyamide

The second polyamide can be processed using a third polyamide and an aromatic reactive compound. 1 to 5 parts by weight of an aromatic reactive compound may be contained relative to 100 parts by weight of the third polyamide, and excellent workability can be maintained within the above range. The second polyamide may have a relative sulfuric acid viscosity of 1.8 to 2.

(1-3) Third polyamide

The third polyamide may use a polyamide having a relative sulfuric acid viscosity of 2.0 to 2.5. When the amount is less than the above range, the impact strength is lowered, and when it is more than the above range, the fluidity is deteriorated, which is not suitable for injection molding.

The third polyamide can be dried and used until the final moisture content in the dryer is 600 ppm or less.

(2) An aromatic reactive compound

In order to lower the viscosity of the polyamide, a long polymer chain can be made short by cracking. The transamidation reaction can be used to effectively decompose the amide bond.

In order to increase the flowability of the resin when cracked, it is advantageous to use an aromatic reactive compound having an aromatic ring which takes up a large amount of free volume so as to prevent entanglement of the polymer chain.

The aromatic reactive compound may be any one selected from an aromatic carboxylic acid compound or an aromatic amine compound. The reactive group may include 1 to 4 groups in the molecule.

 The aromatic carboxylic acid compound may be any of those known in the art but may be selected from the group consisting of isophthalic acid, terephthalic acid, naphthalene dicarboxylic acid, benzoic acid, salicylic acid, acid, trimellitic acid, vanillic acid, and combinations thereof.

The aromatic amine compound may be any of those known in the art, but 1,4-phenylenediamine, 1,3-phenylenediamine, 2,5 2-diaminotoluene, 4-methoxy-m-phenylenediamine, 1,3,5-benzenetriamine and 1,3,5-benzenetriamine. Or a combination thereof.

Among the phthalic acid series having a high affinity with the polyamide, isophthalic acid preferably has a homogeneous structure in order to increase the free volume range by chemical structure. Based on 100 parts by weight of the third polyamide, 1 to 5 parts by weight of isophthalic acid. Within the above range, the flowability is smooth, which is advantageous for extrusion processing, and high-rigidity polyamide low viscosity can be achieved.

(3) Antioxidants

In the case of polyamides modified during long-term heat drying, yellowing may occur within a few days. This is because polyamides with lower molecular weight due to low viscosity modification are oxidized as moisture evaporates. When the polyamide is oxidized, the physical properties are lowered. Therefore, an antioxidant may be used to prevent this phenomenon.

The antioxidant serves to inhibit oxidative degradation reaction during extrusion and injection molding of the composition, and it is preferable that the antioxidant is used by mixing a primary phenol antioxidant and a secondary phosphite antioxidant Do.

The primary phenolic antioxidant reacts with radicals generated in the plastic to release hydrogen in the phenolic antioxidant to stabilize the radical, and the antioxidant itself changes into radicals. And remains in a stable form.

The primary antioxidant may be any of those known in the art if it is a phenolic compound capable of mixing with polyamide to prevent oxidation, but it is preferable to use N, N'-hexane-1,6-diylbis (3- , 5-di-tert.-butyl-4-hydroxyphenylpropionamide), N, N'-di-2butyl-1,4-phenylenediamine, 2,6- butylphenol, 2,6-di-tert-butylphenol, 2,2'-Ethylidenebis (4,6-di-t-butylphenol), 2,2'-Methylenebis (6-t-butyl- ), 4,4'-Butylidenebis (2-t-butyl-5-methylphenol), 4,4'-Thiobis (2- t-butyl-4'-hydroxyphenyl) propionate, and combinations thereof, preferably N, N'-hexane-1,6-diylbis (3- (3,5- tert.-butyl-4-hydroxyphenylpropionamide)).

In addition, the secondary phosphite-based antioxidant functions to release the peroxide to prevent generation of radicals. Phosphite antioxidants can be used synergistically with phenolic antioxidants to increase the stability against UV.

The secondary antioxidant may be any of those known in the art if it is a phosphite-based compound which can be mixed with polyamide to prevent oxidation, but it is preferable to use Tris (2,4-di-tert-butylphenyl) phosphite, Triphenyl phosphite Tris (nonylphenyl) phosphite, Triisodecyl phosphite, Diphenyl-isooctyl-phosphite, Bis (2,6-di-tert-butyl-4-methylphenyl) penta erythritol-diphosphite and combinations thereof. And preferably Tris (2,4-di-tert-butylphenyl) phosphite.

The amount of the primary and secondary antioxidants is preferably 0.1 to 0.5 parts by weight based on 100 parts by weight of the polyamide resin. When the amount of the antioxidant is less than 0.1 parts by weight, If the amount is more than 0.5 parts by weight, the physical properties may deteriorate and the moldability may be deteriorated.

The polyamide resin composition of the present invention can be produced by a conventional method for producing a resin composition and can be extruded using a co-rotating rotary twin-screw extruder capable of screw combination for uniform mixing. The extruder is not particularly limited as long as it can be used for ordinary resin kneading. The cylinder temperature condition of the extruder at this time is preferably 250 to 290 DEG C because the molten state of the resin is uniformly maintained. The number of revolutions of the screw is preferably 200 to 400 rpm. Within the above range, the dispersibility of the resin composition is excellent and the deterioration is small, and the polyamide resin to be produced has excellent impact resistance and processability, and has an effect of realizing an optimal morphology.

(A) mixing 1 to 5 parts by weight of an aromatic reactive compound with 100 parts by weight of a third polyamide to modify the second polyamide;

(b) mixing the first polyamide and the second polyamide in a weight ratio of from 9: 1 to 5: 5;

(c) mixing 0.1 to 0.5 parts by weight of an antioxidant with the polyamide resin mixed in the step (a); And

(d) mixing in a twin-screw extruder heated to 250 to 290 ° C at a rotation speed of 200 to 400 rpm.

The present invention can also be applied to plastic molded articles made of the above polyamide resin composition. For example, it can be applied to parts requiring high rigidity such as interior and exterior materials for automobiles, electric / electronic industrial materials, and building materials. Especially, it is required to have rigidity like automobile CCB (Cowl Cross Bar) and has excellent mechanical property and heat resistance And the like.

Hereinafter, the present invention will be described in detail with reference to examples. However, these are for the purpose of illustrating the present invention in more detail, and the scope of the present invention is not limited by the following examples.

(1) First polyamide: Polyamide 66 having a relative viscosity of 2.5 to 3 (Basf) (2) Third polyamide: Relative viscosity: 2 to 2.5 Polyamide 66 (Basf)

(3) An aromatic reactive compound: benzene-1,3-dicarboxylic acid (reagent)

(4) Primary antioxidant: N, N'-hexane-1,6-diylbis (3- (3,5-di-tert-butyl-4-hydroxyphenylpropionamide)

(5) Secondary antioxidant: Tris (2,4-ditert-butylphenyl) phosphite (Addivant)

[Preparation Example 1] Production of second polyamide

The third polyamide was dried in a dryer until the final moisture content was less than 600 ppm. 3 parts by weight of isophthalic acid was mixed with 100 parts by weight of the third polyamide in the twin-screw extruder.

The extruder was a twin-screw extruder having a diameter of 48 mm and an L / D of 40, and was used in nine heating sections of 250/290/290/290/290/290/290/290/290 ° C at a screw rotation speed of 350 rpm Respectively. After extruding into a strand, it was cooled using a cooling water bath and processed using a pelletizer at 1300 rpm. The shape of the mixture obtained by extrusion showed a pellet shape.

Polaramide resin composition ratio (unit: weight ratio) Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Comparative Example 1 Comparative Example 2 Comparative Example 3 The first polyamide 90 85 80 75 70 60 50 100 - - The second polyamide
(Third polyamide
+ Isophthalic acid) 10 15 20 25 30 40 50 - 100 - The third polyamide - - - - - - - - 100 Primary antioxidant 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Secondary antioxidant 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Relative viscosity 3.03 2.85 2.74 2.65 2.57 2.45 2.38 3.09 1.92 2.33 Melt flow index (g / 10 min) 10.4 15.7 26.7 41.5 64.7 85.5 130.1 7.7 220.35 44.27

The relative viscosity was measured by the Ubbelohde viscometer by ISO 307 sulfuric acid method and the melt flow index was measured by ASTM D 1238 at 270 ° C under a load of 1.2 kg.

[Example 1]

In a twin-screw extruder, the weight ratio of the first polyamide to the second polyamide was adjusted to 9: 1 in the composition ratio shown in Table 1, and 0.2 part by weight of the first antioxidant and 0.2 part by weight of the second antioxidant And 0.2 parts by weight of an antioxidant were mixed.

The extruder was a twin-screw extruder having a diameter of 48 mm and an L / D of 40, and was used in nine heating sections of 250/290/290/290/290/290/290/290/290 ° C at a screw rotation speed of 350 rpm Respectively. After extruding into a strand, it was cooled using a cooling water bath and processed using a pelletizer at 1300 rpm. The shape of the mixture obtained by extrusion showed a pellet shape. The relative viscosity and melt flow index of Example 1 are shown in Table 1 above.

[Examples 2 to 7]

Were prepared in the same manner as in Example 1, except that the components were mixed in the composition ratios shown in Table 1 above. The relative viscosity and melt flow index of Examples 2 to 7 are shown in Table 1 above.

[Comparative Example 1]

In a twin-screw extruder, 100 parts by weight of the first polyamide, 0.2 parts by weight of the first antioxidant and 0.2 parts by weight of the second antioxidant were mixed with 100 parts by weight of the first polyamide.

The extruder was a twin-screw extruder having a diameter of 48 mm and an L / D of 40, and was used in nine heating sections of 250/290/290/290/290/290/290/290/290 ° C at a screw rotation speed of 350 rpm Respectively. After extruding into a strand, it was cooled using a cooling water bath and processed using a pelletizer at 1300 rpm. The shape of the mixture obtained by extrusion showed a pellet shape. The relative viscosity and melt flow index of Comparative Example 1 are shown in Table 1 above.

[Comparative Example 2]

In a twin-screw extruder, 100 parts by weight of a second polyamide, 0.2 parts by weight of a first antioxidant and 0.2 parts by weight of a second antioxidant were mixed with 100 parts by weight of the second polyamide.

The manufacturing method was the same as that of Comparative Example 1 described above. The relative viscosity and melt flow index of Comparative Example 2 are shown in Table 1 above.

[Comparative Example 3]

In a twin-screw extruder, 100 parts by weight of a third polyamide, 0.2 parts by weight of a first antioxidant and 0.2 parts by weight of a second antioxidant were mixed with 100 parts by weight of the third polyamide.

The manufacturing method was the same as that of Comparative Example 1 described above. The relative viscosity and melt flow index of Comparative Example 3 are shown in Table 1 above.

[Test Example]

50% of glass fiber (CS311, CS311) was applied to the resin compositions of the examples and comparative examples. The physical properties of the prepared examples and comparative examples were measured by the following methods, and the results are shown in Table 2.

(1) Melt flow index: Measured by ASTM D 1238 at 270 캜 under a load of 5 kg.

(2) Tensile strength: Measured according to KS M ISO 527.

(3) Flexural strength: Measured according to KS M ISO 178.

(4) Flexural modulus: Measured according to KS M ISO 180.

(5) Impact strength: Measured according to ASTM D256.

(6) Length of glass fiber: 1 g or more of pellet was heated at 600 ° C for 1 hour and 30 minutes in an electric heating furnace, and the length of the remaining glass fiber was measured using an optical microscope.

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Comparative Example 1 Comparative Example 2 Comparative Example 3 Melt flow index (g / 10 min) 18.84 30.15 35.26 40.48 64.05 83.72 88.03 9.53 105.4 8.9 Tensile Strength (Mpa) 227 254 264 247 228 218 209 201 207 179 Flexural Strength (Mpa) 336 360 375 358 350 339 330 313 304 328 Flexural modulus (Gpa) 15.25 15.84 16.27 16.1 14.55 14.11 13.83 13.5 11.2 11.9 Impact strength (kg / cm²) 18.2 17.2 16.4 16.4 15.9 14.3 13.2 20.1 9.6 10.5 Glass fiber length (μm) 559.4 562.2 582.8 612.2 633.6 653.5 807.9 513.2 911.4 551.1

As can be seen from the above Table 2, it can be seen that the glass fiber length increases as the melt flow index increases. This is because the shear force is less applied to the glass fiber due to the low viscosity polyamide.

  As a result of the experiment of the examples, it can be seen that as the length of the glass fiber increases, the physical properties are improved and the physical properties are degraded again from Example 4. [ Thus, even if the length of the glass fiber is kept and the infiltration rate is increased due to the low viscosity, there is a critical point at which the physical properties of the polyamide itself deteriorate and the overall physical properties deteriorate.

As a result, the tensile strength, the flexural strength, the flexural modulus and the impact strength were improved as shown in Example 3 in which the modified polyamide of the present invention was applied while lowering the viscosity of the polyamide, thereby showing excellent mechanical properties.

Claims (11)

0.1 to 0.5 parts by weight of an antioxidant per 100 parts by weight of a polyamide resin in which the weight ratio of the first polyamide and the second polyamide modified with the aromatic reactive compound is 9: 1 to 5: 5, Is 10 g / min or more. The method according to claim 1,
Wherein the first polyamide has a sulfuric acid relative viscosity of 2.5 to 3.0. The method according to claim 1,
Wherein the second polyamide has a sulfuric acid relative viscosity of 1.8 to 2.0. The method according to claim 1,
Wherein the second polyamide is formed by reacting 1 to 5 parts by weight of an aromatic reactive compound with a third polyamide having a sulfuric acid relative viscosity of 2.0 to 2.5. 5. The method of claim 4,
Wherein the aromatic reactive compound is any one selected from an aromatic carboxylic acid compound and an aromatic amine compound. 6. The method of claim 5,
The aromatic carboxylic acid compound may be selected from the group consisting of isophthalic acid, terephthalic acid, naphthalene dicarboxylic acid, benzoic acid, salicylic acid, trimellitic acid, Vanillic acid, and combinations thereof. ≪ RTI ID = 0.0 > 11. < / RTI > 6. The method of claim 5,
The aromatic amine compound may be at least one selected from the group consisting of 1,4-phenylenediamine, 1,3-phenylenediamine, 2,5-diaminotoluene, Wherein the polyamide resin is at least one selected from the group consisting of 4-methoxy-m-phenylenediamine, 1,3,5-benzenetriamine, and combinations thereof. Composition. The method according to claim 1,
Wherein the antioxidant is an antioxidant mixed with a primary antioxidant and a secondary antioxidant. 9. The method of claim 8,
The primary antioxidant is N, N'-di-2-buty-1,4 (4-hydroxyphenylpropionamide) phenylenediamine, 2,6-di-tertbutyl-4-methylphenol, 2,4-dimethyl-6-tert-butylphenol, 2,6- butylphenol), 2,2'-Methylenebis (6-t-butyl-4methylphenol), 4,4'-Butylidenebis (2-t-butyl-5methylphenol), 4,4'- Thiobis -t-butyl-5-methyl phenol, Octadecyl 3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate and combinations thereof. 9. The method of claim 8,
Secondary antioxidants include bis (2,4-di-tert-butylphenyl) phosphite, Triphenyl phosphite, Tris (nonylphenyl) phosphite, Triisodecyl phosphite, Diphenyl- 4-methyphenyl) penta erythritol-diphosphite, and combinations thereof. (a) mixing 1 to 5 parts by weight of an aromatic reactive compound with 100 parts by weight of a third polyamide to modify the second polyamide;
(b) mixing the first polyamide and the second polyamide in a weight ratio of from 9: 1 to 5: 5;
(c) mixing 0.1 to 0.5 parts by weight of an antioxidant with the polyamide resin mixed in the step (a); And
(d) mixing in a twin-screw extruder heated at 250 to 290 占 폚 at a rotation speed of 200 to 400 rpm.