KR20040002055A - Thermoplastic Polyamide Resin Composition and Preparation Method Thereof - Google Patents

Abstract

PURPOSE: Provided is a thermoplastic polyamide resin composition, which has excellent heat resistance, chemical resistance and moldability and is low in deformation and shrinking to be used in a heat resistant component of a car. CONSTITUTION: The polyamide resin composition having excellent heat resistance and chemical resistance comprises about 30-80 wt% of polyamide, about 10-50 wt% of a reinforcing agent and about 0.1-20 wt% of sodium alumina silicate. In particular, the reinforcing agent is a glass fiber, an inorganic filler or a mixture thereof. The polyamide resin composition optionally further comprises about 1-30 phr of a polyolefin, about 1-30 phr of a polyphenylene sulfide or about 1-10 wt% of a polyolefin modified with maleic anhydride.

Description

Thermoplastic Polyamide Resin Composition and Preparation Method Thereof

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to thermoplastic polyamide resin compositions and methods for their preparation, and particularly to high temperature resistance, chemical resistance, low deformation, low shrinkage, and moldability for use in parts of engine parts and cooling water circulators, such as radiator tanks for automobiles. The present invention relates to a thermoplastic polyamide resin composition and a method for producing the same.

In general, the polyamide resin composition has excellent mechanical properties, heat resistance and chemical resistance. In addition, by easily reinforcing various inorganic materials such as glass fiber, carbon fiber, talc, kaolin, ulastonite, calcium carbonate, barium sulfate, very high strength, heat resistance and elastic modulus can be obtained. In addition, various kinds of additives may be added to increase resistance to various chemicals. For this reason, polyamide resin compositions, which are easier to process than metals, have advantages of light weight, and have more free design and design effects, have been widely used in many industries as well as automobiles.

However, there has been a problem of resistance to ethylene glycol, which is a component of antifreeze used in automobile engine cooler systems and chlorides (sodium chloride, calcium chloride, zinc chloride) which are frequently used as an ice making agent in winter.

Therefore, many demanding properties are required for the polyamide resin composition to be used for engine parts of automobiles. The representative ones are heat resistance, ethylene glycol resistance, and chloride resistance. Especially, in order to use the product as a cooler, the performance of the product is exhibited at a high temperature (for example, 120 ° C. or higher), so the heat resistance must be excellent, It must withstand the intrusion of ethylene glycol used. In addition, the chloride used in winter should be able to minimize the damage to the polyamide chain.

US Pat. No. 4,386,197 has attempted to increase the resistance to engine fuels by chemically using caprolactam and ω-aminocarboxylic acids and cycloaliphatic carboxylic acid amides. In this case, the process cost is expensive and the heat resistance tends to increase, but the chemical resistance does not increase particularly.

U.S. Patent No. 4,582,763 describes a method of applying a calcium chloride aqueous solution at a constant temperature and a constant internal pressure by filling a radiator tank with a cap made of polyamide resin, filling an antifreeze component therein, and then applying a depth of crack after a predetermined cycle. The method of measuring the number is disclosed, but since this method is tested with a real product, the design of the product is greatly influenced and the measurement method is very subjective.

In addition, in Journal of Materials Science 22 (1987) 1715-1723, the effects of halogen salts (LiCl, ZnCl ₂ , CaCl ₂ ) and NaCl on polyamide resins were investigated and evaluated in various ways. In this case, evaluation of the halogen salts on the physical properties of the polyamide resin was not made by evaluating the thermal properties and the chemical analysis rather than the physical properties.

U.S. Patent No. 4,482,695 describes polyamide resins that impart gas barrier properties, which are used as a method of increasing the basic chemical resistance by blocking direct contact of chemicals. In this patent, the chemical resistance can be increased by adding bulk resistance by using the aromatic component in the polymerization. However, this was used to prevent gas permeation and was not done on an aqueous alkaline electrolyte solution in water.

Accordingly, it is an object of the present invention to provide a polyamide resin composition having excellent heat resistance, chloride resistance, EG resistance and excellent mechanical properties.

1 is an FT-IR chart of a polyamide resin composition according to Example 2 of the present invention.

2 is an FT-IR chart of a polyamide resin composition according to Example 3 of the present invention.

3 is an FT-IR chart of a polyamide resin composition according to Example 4 of the present invention.

The present inventors have tried to solve the problems of the prior art, and as a result, by mixing a reinforcing agent, sodium alumina silicate, and the like in a specific polyamide resin, a poly having physical properties, heat resistance, low shrinkage, low deformation, internal solution and excellent chloride resistance It has been found that the amide resin composition can be obtained to complete the present invention.

Accordingly, the present invention comprises about 30 to 80% by weight of polyamide, about 10 to 50% by weight of reinforcing agent and about 0.1 to 20% by weight of sodium alumina silicate, physical properties, heat resistance, low shrinkage, low deformation, resistance Provided is a polyamide resin composition having excellent antifreeze resistance and chloride resistance.

The polyamide resin can be any polyamide resin known in the art.

Reinforcing agents included in the polyamide resin composition of the present invention include glass fibers, inorganic fillers or combinations thereof. The reinforcing agent may be kaolin, ulestonite, barium sulfate, calcium carbonate, or the like, but other materials known to those skilled in the art may be used.

In addition, the polyamide resin composition of the present invention has a polyolefin and / or polyphenylene of about 1 to 30 phr (phr is "part per hundred resin" means a content ratio of the other components based on the resin 100) It may further include a sulfide. The polyamide resin composition of the present invention may further comprise a polyolefin modified with about 1 to 10% by weight of maleic anhydride.

In particular, the resin composition according to the present invention can be widely used in engine parts and cooling circulation parts and parts requiring long-term heat resistance of an automobile because of its excellent heat resistance, internal liquid resistance and chloride resistance and very low deformation after injection.

Each component contained in the resin composition of this invention is demonstrated in detail below.

Representatively known polyamide resins include polyamide 6, aminocapronic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, etc., which are obtained by ring-opening polymerization of commonly known lactams such as ε-caprolactam and ω-dodecaractam. Polyamide polymers obtained from amino acids of ethylenediamine, tetramethylenediamine, hexamethylenediamine, undecamethylenediamine, dudecamethylenediamine, 2,2,4-trimethylhexamethylenediamine, 2,4,4-trimethylhexa Methylenediamine, 5-methylnonahexamethylenediamine, metaxylenediamine, paraxylenediamine, 1,3-bisaminomethylcyclohexane, 1,4-bisaminomethylcyclohexane, 1-amino-3-aminomethyl-3, 5,5-trimethylcyclohexane, bis (4-aminocyclohexane) methane, bis (4-methyl-4-aminocyclohexyl) methane, 2,2-bis (4-aminocyclohexyl) propane, bis (aminopropyl Piperadine, army Aliphatic, cycloaliphatic, aromatic diamines and adipic acids, such as ethyl piperadines, aliphatic acids such as spernic acid, sebacic acid, azeline acid, terephthalic acid, inphthalic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, and 5-methylinphthalic acid; The polyamide polymer obtained from alicyclic, aromatic dicarboxylic acid, etc., the copolymer or mixture of the said polyamide resin, etc. can be used.

Preferred examples of the polyamide resin include polyamide 6, polyamide 6,6, polyamide 6,10, polyamide 11, polyamide 12, polyamide 6,12, polyamide 6,36, polyamide copolymer, aliphatic poly Mention may be made of amides, terephthalic acid or isophthalic acid based polyamides, aromatic polyamides or combinations thereof.

Among the above polyamides, in order to improve chloride resistance, it is preferable to use a mixture or copolymer containing polyamide 6,6 alone or as a main component thereof. Most preferably, polyamide 6,6 and polyamide 6,10, polyamide 6,12 or polyamide 6,36 may be mixed in a proportion.

When polyamide 6,6 alone is used, it shows a serious decrease in physical properties after exposure experiment due to the penetration of chloride by moisture absorption, but aliphatic by using a certain amount of additive, polyolefin component, and optionally polyphenylene sulfide having ion exchange ability. The chains can have almost the same effect as the chlorides provided by the relatively long, ie low hygroscopic polyamides.

The relative viscosity of the polyamide-based resin is about 1.0-4.0, preferably 2.0 to 3.7 (dissolve 1 g of the polymer in 100 ml of 96% sulfuric acid, the temperature is 25 ℃), particularly preferably 2.0-3.0 The number average molecular weight is about 5,000 ~ 70,000 is easy to use. Typical structural formulas of the known polyamide resins are as follows.

<Polyamide 6,6>

-[-HN- (CH ₂ ) ₆ -NHCO- (CH ₂ ) ₄ -CO-]-

<Polyamide 6,6 / 6 (copolymer)>

-[-HN- (CH ₂ ) ₆ -NHCO- (CH ₂ ) ₄ -CONH- (CH ₂ ) ₅ -CO-]-

<Polyamide 6,10>

-[-HN- (CH ₂ ) ₆ -NHCO- (CH ₂ ) ₈ -CO-]-

<Polyamide 6,12>

-[-HN- (CH ₂ ) ₅ -NHCO- (CH ₂ ) ₁₀ -CO-]-

<Polyamide 6,36>

-[-HN- (CH ₂ ) ₅ -NHCO- (CH ₂ ) ₃₄ -CO-]-

The reinforcing agent can be used within the range of about 10 to 50% by weight in order to significantly improve the rigidity and heat resistance of the polyamide composition and to achieve low shrinkage and low deformation. Reinforcing agents can be used glass fibers, inorganic fillers or combinations thereof. Examples of the inorganic fillers may include kaolin, ulstonite, barium sulfate, calcium carbonate and the like.

The average particle length of the glass fiber is 3 to 3.2 µm, the diameter is about 10 µm, and a silane-based silane coupling agent is treated on the surface of the glass fiber to impart compatibility with the polyamide resin. For the most effective stiffness and heat resistance addition, it is appropriate to use 10 to 50% by weight glass fiber. The size of the inorganic filler is 0.1 to 5 mu m, and the particle diameter is 2.5 mu m or less.

By adding about 0.1-20% by weight of the sodium alumina silicate additive to the composition of the present invention, it is possible to capture metal ions through ion exchange to significantly increase chloride resistance without deteriorating heat resistance. This can significantly increase only the chloride resistance without damaging the heat resistance, rigidity and internal liquid resistance, which are basic characteristics of the initial glass fiber reinforced polyamide resin.

Dissociated metal ions that have penetrated into the polyamide chains with water in the presence of water can cause ultimate cracks by interfering with hydrogen bonds between the chains of the polyamide with continuous deposition at high temperatures. At this time, the additive itself may selectively trap only metal ions, thereby delaying the collapse of the polyamide resin due to subsequent exposure of chloride.

Wide processing range by improving the chloride resistance while increasing the water resistance of the polyamide resin composition, and improving the compatibility of general polyolefin and polyamide which can be added to improve the appearance characteristics and low shrinkage of the product. The modified polyolefin modified with polyolefin and / or maleic anhydride may be optionally included in the resin composition of the present invention to obtain a certain level of physical properties. Modified polyolefins are of copolymer type and graft type. By using about 1 to 10% by weight of polyolefin and modified polyolefin, excellent chloride resistance can be obtained, and the internal copper liquid resistance can also be significantly increased. On the other hand, using a large amount may impair excellent properties such as the rigidity of the polyamide itself.

Polyphenylene sulfide can be used in addition to a small amount of about 1 to 10% by weight to give a noticeable effect even in high mechanical properties, internal fluid and calcium chloride resistance. The structure of the polyphenylene sulfide used in the present invention is as follows.

(F) Polyolefin generally means polypropylene and polyethylene, and may be used 1 to 30% by weight.

In addition, antioxidants, heat stabilizers, ultraviolet absorbers, processing dispersants, pigments, dyes, surfactants, mold release agents, lubricants, plasticizers, brighteners, antistatic agents, and the like, which are generally used as plastic processing agents within the scope of not objecting to the present invention, Additives such as dispersants, carbon black and the like can be used to impart various effects.

The present invention is designed to give heat resistance and excellent mechanical properties among the properties of the polyamide and at the same time have internal copper liquid resistance and chloride resistance. The longer the aliphatic chain is, the longer the aliphatic chain is, the longer the aliphatic chain is, the lower the initial physical properties and the lower the number of amide functional groups per unit mass, thereby reducing the reactivity with the glass fiber treated with the coupling agent. As a result, the antifreeze is violated significantly.

The resin composition of the present invention having the above composition has better mechanical properties and internal liquid resistance than a composition composed of polyamide 6,10, polyamide 6,12 or polyamide 6,36, and the like, and has almost the same level of chloride resistance as functional. Can be given by.

Therefore, the heat resistant and chemical resistant resin composition according to the present invention can be applied to interior and exterior products requiring heat resistance and rigidity such as a radiator tank cap of a vehicle, a general boiler, and the like.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by the following Examples.

<Example>

Hereinafter, a method for producing a polyamide resin composition according to the present invention and the general properties of the polyamide resin composition according to the present invention as described below, namely, mechanical properties (tensile strength, flexural strength, flexural modulus, Izod impact strength, high-speed drop impact, and thermal deformation temperature) And the good properties of the composition of the present invention by comparing the shrinkage properties. However, this is merely illustrative and does not limit the present invention.

First, each component used in Examples and Comparative Examples of the present invention will be classified and described as follows.

1) Crystalline Polyamide Resin

A-1: Polymer obtained by polycondensation of hexamethylenediamine and adipic acid as crystalline polyamide 6,6 in equimolar ratio, having a relative viscosity (96% sulfuric acid, a solution of 1 g of polymer in 100 ml, measured at 23 ° C) of 2.6 Use a product with a melting point of 260 ° C.

A-2: Crystalline polyamide 6,10, obtained by polycondensation of hexamethylenediamine and sebacic acid in equimolar ratio, having a relative viscosity (96% sulfuric acid, a solution of 1 g of polymer in 100 ml, measured at 23 ° C) of 2.0 or more Use a product with a melting point of 210 ℃.

A-3: A crystalline polyamide 6,36, obtained by polycondensation of hexamethylenediamine and oleic acid in an equimolar ratio, having a relative viscosity (96% sulfuric acid, a solution of 1 g of polymer in 100 ml, measured at 23 ° C) of 1.5 or more. , Use product with melting point of 200 ℃.

A-4: Polymer obtained by polycondensation of hexamethylenediamine and dodecanoic acid as crystalline polyamide 6,12 in equimolar ratio, relative viscosity (96% sulfuric acid, 1 g solution of polymer in 100 ml, measured at 23 ° C) of 1.8 or more Using a product having a melting point of 185 ° C.

2) Polyolefin Modified with Maleic Anhydride

B: The modified polyolefin is a copolymer or graft copolymer of 10 to 99% by weight of a polyolefin polymer and 1 to 20% by weight of maleic anhydride monomer.

3) additive

C: Sodium Alumina Silicate

4) glass fiber

D: The average particle length is 3 to 3.2 µm, the diameter is about 10 µm and treated with a silane coupling agent of the silane system in order to give compatibility with the polyamide resin on the glass fiber surface.

5) polyphenylene sulfide

E: Resin made from p-dichlorobenzene and Na ₂ S as a raw material, and having a melting point of 278 ° C.

6) polyolefin

F: common polyethylene and polypropylene

The components selected as described above were uniformly mixed in the supermixer according to the mixing ratios of the examples and the comparative examples as shown in Tables 1 and 2 below. Both extruders having a single screw or twin screw can be used, but in this embodiment, an extruder having a twin screw (inner diameter 30 mm, L / D = 30) was used, wherein the cylinder temperature in the extruder was 260-280 ° C., the screw The rotational speed was set at 250-300 rpm, the vacuum pump (for discharging gas in the screw) was 50-70 mmHg, and the discharge amount was set at 25-30 kg / hr to melt and mix the composition of each example in the extruder cylinder. Was formed. The formed lace was cooled in a water cooling bath, and then prepared into pellets of a predetermined size using a pelletizer.

In order to remove the water contained in the thus prepared pellets was dried for 12 hours at 85 ~ 90 ℃ using a nitrogen atmosphere oven. Pellets with a water content of 0.1% or less are formed at a molding temperature of 290 ° C or 280 ° C, a mold temperature of 80 ° C, an injection pressure of 50 to 80 bar, an injection rate of 40 to 60 mm / sec, and an injection and cooling time of 3 seconds and 15 seconds, respectively. Under the conditions, 80 tons, 6.4 ounces of the injection machine (made in Germany, Engel) was processed, and the specimen for different characteristics evaluation was produced.

Various properties of the prepared ASTM specimens were evaluated by the following evaluation methods, and the components and contents used in the resin compositions of Examples and Comparative Examples and various characteristics of the compositions are shown in Tables 1 and 2, respectively.

The evaluation items and analysis methods of the specimen are as follows.

a) Tensile strength: It was analyzed by using Instron equipment according to the test method of ASTM D-638. The unit is kgf / cm ² .

b) Flexural strength and flexural modulus: analyzed using Instron equipment according to the test method of ASTM D-790. Each unit is kgf / cm ² .

c) Izod impact strength: analyzed using an Izod impact machine according to ASTM D-256. The unit is kgfcm / cm.

d) Heat Deflection Temperature: The heat deflection temperature was measured at 4.6 kgf / cm ² load by ASTM D-648.

e) Shrinkage: The shrinkage of each composition was calculated by ASTM D-955. The unit is%.

f) Internal Copper Liquid Resistance: After immersing the ASTM specimen for tensile strength evaluation in 50:50 water and ethylene glycol aqueous solution (146 ℃) for 144 hours, and in a constant temperature and humidity room (25 ℃, 50% relative humidity) for 24 hours After being left for a while, a tensile strength test (ASTM D-638) was performed.

g) Calcium chloride resistance: Tensile strength test (ASTM D-638) was immersed in a 10 wt% anhydrous chloride solution (150 ° C.) for 300 hours and then left in a constant temperature and humidity room (25 ° C., 50% relative humidity) for 24 hours. Was carried out.

Ingredient Comparative Example 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 A-1A-2A-3A-4BCDEF 70000003000 67000033000 64000333000 540003330100 541000333000 59000333005 540100333000 Tensile Strength Flexural Strength Flexural Modulus Izod Impact Strength Heat Deflection Temperature Shrinkage (Flow / Reverse Flow) Internal Fluid Resistance Calcium Chloride Resistance 1821263487410112600.4 / 0.7548498 1810265086300112600.4 / 0.7652584 1803255085000122550.4 / 0.7605651 1853261492630122650.4 / 0.7629687 1814255083050122580.4 / 0.7599635 1795255185670162500.4 / 0.7612673 1751243082309142450.4 / 0.7619623

Comparative Example 1 combines a simple polyamide 6,6 with 30% by weight of glass fiber and a heat-resistant component to induce a covalent bond between an amide functional group at the polyamide end and a glass fiber surface-treated with a silane coupling agent.

Example 1 had the function of trapping the cations penetrated into the chain by adding sodium alumina silicate to Comparative Example 1, thereby selectively increasing only the resistance of chlorides without deteriorating antifreeze properties and initial physical properties.

Example 2 is the addition of modified polyolefin to Example 1, but slightly lower initial physical properties and internal copper fluid compared to Example 1, but shows very good chloride resistance.

FIG. 1 is an FT-IR chart of a polyamide resin composition according to Example 2 of the present invention, in which characteristic peaks due to the inherent structure of the present filler only in ion exchange capacity appear at around 1750 cm ^{−1 and} around 630 cm ⁻¹ . , Around 1000 cm ^-1 , a typical Si-O ₂ peak appears.

Example 3 is the addition of polyphenylene sulfide to Example 2, showing the best properties in the initial physical properties, internal liquid resistance and chloride resistance.

FIG. 2 is an FT-IR chart of the polyamide resin composition according to Example 3 of the present invention, in which inherent peaks of polyolefins different from those in Example 2 are observed at around 580 cm ⁻¹ and 460 cm ⁻¹ .

In Example 4, polyamide 6,10 was added to Example 2, but the initial physical properties and LLC properties were slightly lower, but showed excellent properties in chloride resistance.

3 is an FT-IR chart of the polyamide resin composition according to Example 4 of the present invention, wherein peaks of polyphenylene sulfide are observed at around 810 cm ^{−1 and} around 1200 cm ⁻¹ .

Example 5 is a case in which the polyolefin is further added to Example 2, the internal copper liquid resistance is not very high, but the chloride resistance is remarkably high.

In Example 6, polyamide 6,36 was added to Example 2, and the internal copper liquid resistance was relatively low, but the chloride resistance was excellent.

Ingredient Example 7 Example 8 Example 9 Example 10 Example 11 Example 12 A-1A-2A-3A-4BCDEF 540010333000 440020333000 440200333000 442000333000 600000103000 440003330200 Tensile Strength Flexural Strength Flexural Modulus Izod Impact Strength Heat Deflection Temperature Shrinkage (Flow / Reverse Flow) Internal Fluid Resistance Calcium Chloride Resistance 1800250082500132530.4 / 0.7615695 1750245081000152480.4 / 0.7603685 1700240080500152400.4 / 0.7605657 1795249582555132550.4 / 0.7598654 1895269487554102630.4 / 0.7655603 1950283598570112680.4 / 0.7653702

Example 7 shows that the addition of 10% by weight of polyamide 6,12 to Example 2 results in superior initial physical properties and internal copper liquid properties, but excellent chloride resistance.

In Example 8, by adding 10% by weight of polyamide 6,12 to Example 7, initial physical properties and internal copper liquid properties were slightly lower, but showed better properties in chloride resistance.

Example 9 is a case in which 10 wt% of polyamide 6,36 is further added to Example 6, and the internal copper solution property is relatively lower than that of Example 6, and the chloride resistance is excellent.

In Example 10, 10 wt% of polyamide 6,10 was added to Example 4, and the initial physical properties and internal copper liquid properties were slightly lower, but showed excellent properties in chloride resistance.

Example 11 had the function of trapping the cation penetrated into the chain by adding sodium alumina silicate to Comparative Example 1, so that the antifreeze and initial physical properties were increased, and only the resistance of chloride could be selectively increased.

In Example 12, 10 wt% of polyphenylene sulfide was added to Example 3, which shows more excellent properties in initial physical properties, internal copper liquid resistance, and chloride resistance.

As described above, the polyamide resin composition according to the present invention has superior mechanical properties and internal liquid resistance than conventional resin compositions, and has almost the same level of chloride resistance. Therefore, the composition according to the present invention can be applied to various interior and exterior products requiring heat resistance and rigidity, such as a radiator tank cap of a motor vehicle, a general boiler, and the like.

Claims (7)

A polyamide resin composition having excellent heat resistance and chemical resistance, comprising about 30 to 80 weight percent polyamide, about 10 to 50 weight percent reinforcement, and about 0.1 to 20 weight percent sodium alumina silicate. The polyamide of claim 1, wherein the polyamide is polyamide 6, polyamide 6,6, polyamide 6,10, polyamide 11, polyamide 12, polyamide 6,12, polyamide 6,36, polyamide copolymer, A polyamide resin composition selected from the group consisting of aliphatic polyamide, terephthalic acid or isophthalic acid polyamide, and aromatic polyamide polyamide. The polyamide resin composition according to claim 1, wherein the reinforcing agent is glass fiber, an inorganic filler or a combination thereof. The polyamide resin composition according to claim 1 or 2, further comprising about 1 to 30 phr of polyolefin. The polyamide resin composition of claim 1 or 2, further comprising about 1 to 30 phr of polyphenylene sulfide. The polyamide resin composition according to claim 1 or 2, further comprising about 1 to 10% by weight of polyolefin modified with maleic anhydride. The polyamide composition according to claim 1 or 2, which is used for radiator tank caps, engine covers, timing belt caps, and parts of engine and cooler systems of automobiles.