JP3887354B2 - Thermoplastic polyamide resin composition and method for producing the same - Google Patents

Description

  The present invention relates to a thermoplastic polyamide resin composition and a method for producing the same.

  Specifically, the present invention relates to a thermoplastic polyamide resin composition having high heat resistance, high chemical resistance, low deformation, low shrinkage and good moldability. The resin of the present invention can be used for a cooling device such as a radiator tank cap for a cooling water circulation device, and an automobile part such as an engine cover, a timing belt cap and other engine parts. The present invention also includes a method for producing the resin of the present invention.

  In general, the polyamide resin composition should have good mechanical properties, heat resistance and chemical resistance. The resin composition can easily reinforce various inorganic materials such as glass fiber, carbon fiber, talc, kaolin, wollastonite, calcium carbonate and barium sulfate to obtain high strength, heat resistance and elasticity. Furthermore, resistance to various chemical substances can be improved by adding various types of additives to the composition. For these reasons and because they are easier to process than metals and the weight of the material made is lighter, polyamide resin compositions can be used in many industrial fields, including the automotive industry.

  Problems associated with conventional polyamide resin compositions include chlorides (sodium chloride, calcium chloride, zinc chloride, etc.) widely used as anti-icing agents in winter and components of antifreeze used in automotive engine cooling systems. Some have low resistance to aqueous ethylene glycol solutions.

  Therefore, the polyamide resin composition has many strict regulations in terms of characteristics for use as a part of an automobile engine. Its typical properties are heat resistance and resistance to ethylene glycol and chloride. In particular, since the cooling system must exhibit performance at high temperatures (eg, 120 ° C. or higher), the resin composition needs to exhibit good heat resistance in order to apply the composition to the cooling system, It must also be resistant to the erosion of ethylene glycol used as engine coolant. Furthermore, the resin composition should be capable of minimizing damage to the polymer chains by chlorides often used in winter.

  U.S. Pat. No. 4,386,197 shows an attempt to increase engine fuel resistance by using a binary copolyamide comprising a polymeric reaction product of caprolactam or ω-aminocarboxylic acid and a cycloaliphatic carboxylic acid amide. Has been. However, the cost to produce the copolyamide is expensive and the copolyamide tends to have increased heat resistance but does not have particularly improved chemical resistance.

  U.S. Pat. No. 4,582,763 discloses a method for measuring the depth and number of cracks in caps made of polyamide resin. Specifically, according to this method, the radiator tank is capped with a cap and then filled with antifreeze components, to which an aqueous solution of calcium chloride is applied at a temperature and internal pressure. Thereafter, after several cycles under specified conditions, the depth and number of cracks in the cap are measured. Although the disclosed method tests actual commercial products to measure crack properties, the test data may be affected by the design of the test product, and this measurement method is in a subjective manner. It is done.

Journal of Materials Science 22 (1987) 1715-1723 discloses the influence of halogen salts (LiCl, ZnCl ₂ , CaCl ₂ ) and NaCl on polyamide resins. In this case, the effect is measured primarily by thermal properties or chemical analysis rather than by physical properties. Accordingly, nothing has been measured as to how the halogen salt affects the physical properties of the polyamide resin.

U.S. Pat. No. 4,482,695 discloses a polyamide resin having gas barrier properties, which exhibits increased chemical resistance by preventing direct contact with chemicals. Resin resistance to chemicals is enhanced by adding bulk properties to the polyamide using aromatic components during the polymerization of the polyamide. However, this resin is used for laying and storing gas permeation, and its chemical resistance has not been measured in aqueous alkaline electrolyte solutions.
U.S. Pat. No. 4,386,197 U.S. Pat. No. 4,582,763 U.S. Pat. No. 4,482,695 Journal of Materials Science 22 (1987) 1715-1723

  An object of the present invention is to provide a polyamide resin composition having good heat resistance, high chloride resistance, high ethylene glycol resistance and good mechanical properties.

  Specifically, the polyamide resin composition according to the present invention comprises about 30-80% by weight polyamide, about 10-50% by weight reinforcing agent and about 0.1-20% by weight sodium aluminate silicate.

  The present invention is based on research to achieve the above object, and by mixing a specific polyamide resin with a reinforcing agent and sodium alumina silicate, good physical properties, high heat resistance, low shrinkage, low It includes the discovery that a polyamide resin composition having deformation, high chloride resistance and high antifreeze resistance can be obtained.

  Thus, the present invention comprises about 30-80% by weight polyamide, about 10-50% by weight reinforcing agent and about 0.1-20% by weight sodium aluminate silicate, with good physical properties, high heat resistance, low shrinkage, Provided is a polyamide resin composition having low deformation, high chloride resistance and high antifreeze resistance.

  Any polyamide resin known in the art can be used in the polyamide resin composition according to the present invention.

  Reinforcing agents included in the polyamide resin composition of the present invention can include glass fibers, inorganic fillers, and combinations thereof. Possible reinforcing agents include, for example, kaolin, wollastonite, calcium carbonate and barium sulfate, although other sub-amounts well known in the art can be used.

  The polyamide resin composition of the present invention may further contain about 1 to 30 parts of polyolefin and / or polyphenylene sulfide as the number of parts per 100 parts of resin (p time). The composition may further contain about 1 to 10% by weight of a polyolefin modified with maleic anhydride.

  The polyamide resin composition of the present invention has particularly excellent heat resistance, antifreeze resistance and chloride resistance, and exhibits low deformation after injection molding, thus requiring parts for automobile engines and cooling devices and long-term heat resistance. As a part to be used, it can be widely used.

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

  Polyamide resins that can be used in accordance with the present invention are well known in the relevant art. Representative examples of this polyamide resin include polyamide 6, aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid obtained by ring-opening polymerization of a lactam such as ε-caprolactam and ω-dodecalactam. Polyamide, ethylenediamine, tetramethylenediamine, hexamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4-trimethylhexamethylenediamine, 2,4,4- Trimethylhexamethylenediamine, 5-methylnonahexamethylenediamine, m-xylenediamine, p-xylenediamine, 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 1-amino-3 -Amino-me Til-3,5,5-trimethylcyclohexane, bis (4-aminocyclohexyl) methane, bis (4-methyl-4-aminocyclohexyl) methane, 2,2-bis (4-aminocyclohexyl) propane, bis (aminopropyl) ) -Aliphatic, cycloaliphatic or aromatic diamines such as piperazine, aminoethylpiperazine and the like and adipic acid, suberic acid, sebacic acid, azelaic acid, terephthalic acid, isophthalic acid, 2-chloroterephthalic acid, 2-methyl- Included are polyamides obtained by polymerization with aliphatic, cycloaliphatic or aromatic dicarboxylic acids such as terephthalic acid, 5-methylisophthalic acid and the like, as well as mixtures thereof.

  Examples of preferred polyamide resins include polyamide 6, polyamide 6,6, polyamide 6,10, polyamide 11, polyamide 12, polyamide 6,12, polyamide 6,36, polyamide copolymer, aliphatic polyamide, polyamide (terephthalic acid or isophthalic acid). Acid)), aromatic polyamides or mixtures thereof.

  Among these polyamides, in order to improve chloride resistance, it is preferable to use a single polyamide 6,6 or a mixture or copolymer of polyamide 6,6 as a main component and another polyamide. Particularly preferably, a mixture having a specific mixing ratio of polyamide 6,6 and polyamide 6,10, polyamide 6,12 or polyamide 6,36 can be used.

  When polyamide 6,6 is used alone, this polyamide resin composition exhibits severe physical property degradation due to chloride penetration into the polyamide chain due to moisture absorption after exposure. However, this composition provides a low-absorbency polyamide having a relatively long aliphatic chain by adding a predetermined amount of an additive having an ion exchange capacity, a polyamide component, and an optional polyphenylene sulfide. Can exhibit almost the same level of chloride resistance.

The relative viscosity of the polyamide resin (measured as a solution of 1 g of polymer in 100 ml of 96% sulfuric acid at 23 ° C.) is preferably in the range of about 1.0 to 4.0, 2.0 to 3. It is preferably in the range of 7%, more preferably in the range of 2.0-3.0%, and the average molecular weight useful for use in the present invention is in the range of about 5000-70000. Representative polyamides well known in the art can be represented by the general formula:
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-]-
Polyamide 12:
-[-NHC- (CH ₂ ) ₁₀ -CO-]-

  By using the reinforcing agent in an amount of about 10 to 50% by weight, the rigidity can be remarkably improved, and low shrinkage and low deformation of the polyamide resin composition can be secured. Examples of reinforcing agents include glass fibers, inorganic fillers, and combinations thereof. Examples of inorganic fillers include kaolin, wollastonite, barium sulfate and calcium carbonate.

  The glass fiber has an average particle length of 3 to 3.2 μm and a diameter of about 10 μm, and its surface is treated with a silane type silane coupling agent to make it compatible with the polyamide resin. In order to provide rigidity and heat resistance particularly effectively, the glass fiber is preferably used in an amount of 10 to 50% by weight. The inorganic filler has a length of 0.1 to 5 μm and a particle size of 2.5 μm or less.

  When the sodium aluminate silicate additive is added to the composition according to the present invention in an amount of about 0.1 to 20% by weight, the composition is supplemented with metal ions by ion exchange, so that the heat resistance is not deteriorated. The chloride resistance of can be specifically increased. Therefore, the chloride resistance can be improved specifically and significantly without deteriorating the initial basic characteristics of the polyamide resin reinforced with glass fibers such as heat resistance, rigidity and antifreeze resistance.

  The separated metal ions penetrate into the polyamide chain together with water in the presence of moisture, and adhere continuously at high temperatures, thereby eventually forming cracks in the polyamide resin. This erodes the formation of hydrogen bonds between the polyamide chains. However, by selectively trapping metal ions with the additive, the decay of the polyamide resin caused by continuous exposure to chloride can be delayed.

  The polyamide resin composition according to the present invention comprises a modified polyolefin optionally modified with polyolefin and / or maleic anhydride, so that the polyamide resin composition has improved resistance to moisture and chloride and a polyamide for general polyolefins. Which are added to improve the appearance of the product and for low shrinkage, to maintain a certain level of physical properties in a wide range of processing Can be improved. The modified polyolefin may be of a copolymer type or a graft polymer type. When the polyolefin and / or modified polyolefin is used in an amount of 1 to 10% by weight, excellent chloride resistance can be obtained, and antifreeze resistance can be remarkably enhanced. If the amount of polyolefin used exceeds 10% by weight, the excellent properties of the polyamide itself such as rigidity may be impaired.

In addition, the use of polyphenylene sulfide in a small amount of about 1 to 10% by weight can enhance the mechanical and physical properties of the resin composition and has a significantly improved effect on resistance to antifreeze and calcium chloride. Can be achieved. Polyphenylene sulfide has the general structure shown below.

  As used herein, the term “polyolefin” generally refers to polypropylene and polyethylene, which can be used in amounts of 1 to 30% by weight.

  In addition to the above components, as long as it is within the scope of the present invention, various additives such as antioxidants, heat stabilizers, UV absorbers, processing dispersants, pigments, dyes, surfactants Various additives such as an agent, a release agent, a lubricant, a plasticizer, an antistatic agent, a dispersant, and carbon black can be added to the polyamide resin composition.

  In view of the general characteristics of polyamide, when the length of the aliphatic chain increases, the water absorption, which is the initial physical property of the polyamide, decreases, and the number of amide functional groups per unit weight of the polyamide decreases. As a result, the reactivity with the glass fiber treated with the coupling agent is lowered, and is considerably damaged by the penetration of the antifreeze. This polyamide resin composition is designed to have heat resistance, excellent mechanical and physical properties, and resistance to antifreeze and chloride.

  The resin composition according to the present invention having the above composition has better mechanical and physical properties and antifreeze resistance than conventional compositions made of polyamide 6,10, polyamide 6,12, polyamide 6,36, It also provides functional resistance to chloride.

  Thus, the heat-stable and chemical-resistant resin composition according to the present invention is suitable for internal and external parts requiring heat resistance and rigidity, such as boilers, automobile radiator tank caps, engine covers and timing belt caps. Etc. can be used.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail with reference to an Example, these Examples do not limit the scope of the present invention.

  Examples 1-13 below describe the preparation of polyamide resin compositions according to the present invention and show various properties of each composition, such as mechanical and physical properties ( For example, tensile strength, bending strength, flexural modulus, Izod impact strength, thermal deformation temperature) and shrinkage characteristics are compared with each other. However, it should be understood that the following examples are included for illustrative purposes only and are not intended to limit the scope of the invention.

  First, each composition used in the examples and comparative examples will be described below.

(1) Crystalline polyamide resin A-1: 2.6 relative viscosity prepared by condensation polymerization of hexamethylenediamine and adipic acid in equimolar ratio (solution of 1 g of polymer in 100 ml of 96% sulfuric acid) As measured at 23 ° C) and a commercially available crystalline polyamide 6,6 having a melting point of 260 ° C.

A-2: A relative viscosity of at least 2.0, prepared by condensation polymerization of hexamethylenediamine and sebacic acid in an equimolar ratio (measured as a solution of 1 g of polymer in 100 ml of 96% sulfuric acid at 23 ° C.) And commercially available crystalline polyamide 6,10 having a melting point of 210 ° C.

A-3: A relative viscosity of at least 1.5, prepared by condensation polymerization of hexamethylenediamine and oleic acid in equimolar ratio (measured as a solution of 1 g of polymer in 100 ml of 96% sulfuric acid at 23 ° C.) And commercially available crystalline polyamide 6,36 having a melting point of 200 ° C.

A-4: A relative viscosity of at least 1.8, prepared by condensation polymerization of hexamethylenediamine and dodecanoic acid in an equimolar ratio (measured as a solution of 1 g of polymer in 100 ml of 96% sulfuric acid at 23 ° C.) And commercially available crystalline polyamide 6,12 having a melting point of 185 ° C.

A-5: commercial product prepared by condensation polymerization of ω-aminodecanoic acid, having a relative viscosity of at least 2 (measured at 23 ° C. as a solution of 1 g of polymer in 100 ml of 96% sulfuric acid) and a melting point of 180 ° C. Crystalline polyamide 12 available as

(2) Maleic anhydride modified polyolefin B: This modified polyolefin is a copolymer or graft copolymer comprising 10 to 99% by weight of polyolefin and 1 to 20% by weight of maleic anhydride monomer.

(3) Additive C: Sodium alumina silicate

(4) Glass fiber D: Glass fiber having a diameter of about 10 μm and an average particle length of 3 to 3.2 μm and treated with a silane type silane coupling agent to make it compatible with the polyamide resin.

(5) Polyphenylene sulfide E: a resin having a melting point of 278 ° C. prepared using p-dichlorobenzene and Na ₂ S as raw materials.

(6) Polyolefin F: General polyethylene and polypropylene.

  In the Super mixer, the above components were homogeneously mixed at the mixing ratios of Examples and Comparative Examples as shown in Tables 1 and 2. Both single screw and twin screw extruders can be used, but the extruder used in these examples is a twin screw extruder (inner diameter 30 mm, L / D = 30) and its cylinder temperature is The rotation speed of the screw was 250 to 300 rpm, the pressure of the vacuum pump (for discharging the gas in the screw) was 50 to 70 mmHg, and this discharge was set to 25 to 30 kg / hour. The compositions of each example were then fully melted and mixed in an extruder cylinder to form a race. The formed lace was cooled in a water bath and then formed into pellets of a predetermined size with a pelletizer.

  The produced pellets were dried in an oven at 85 to 90 ° C. under a nitrogen atmosphere to remove moisture contained in the pellets. Pellets having a moisture content of 0.1% or less are molded in an extruder (ANGEL, DE) having a capacity of 80 tons, 6.4 oz. Samples for measuring various properties were prepared by processing under molding conditions such as an injection pressure of -80 bar, an injection speed of 40-60 mm / sec, an injection time of 3 sec, and a cooling temperature of 15 sec.

  Various properties were measured on the prepared ASTM sample according to the following analysis method. Tables 1 and 2 show the contents of the components used in the resin compositions of Examples and Comparative Examples, and measurements on various characteristics of the samples.

  The parameters and analysis methods for sample evaluation are as follows.

(A) Tensile strength: Measured using an Instron device according to ASTM method D-638. This is expressed in kgf / cm ² .

(B) Flexural strength and flexural modulus: These were measured using an Instron device according to ASTM method D-790. These are expressed in kgf / cm ² .

(C) Izod impact strength: Measured using an Izod impact tester according to ASTM method D-256. This is expressed in kgf · cm / cm.

(D): Thermal deformation temperature: Measured under a load of 4.6 kgf / cm ² according to ASTM method D-648.

(E) Shrinkage: The shrinkage of each sample was calculated according to ASTM method D-955. It is expressed in%.

(F) Antifreeze resistance: ASTM samples for measuring tensile strength were immersed in an aqueous solution consisting of water and ethylene glycol (50:50) at 146 ° C. for 144 hours and then a constant temperature / humidity chamber (25 C. and 50% relative humidity) for 24 hours. A tensile test was then performed according to ASTM method D-638.

(G) Calcium chloride resistance: The sample was immersed in an aqueous 10% by weight anhydrous calcium chloride solution at 150 ° C. for 300 hours and then placed in a constant temperature / humidity chamber (25 ° C., 50% relative humidity) for 24 hours. . A tensile test was then performed according to ASTM method D-638.

  The polyamide resin composition of Comparative Example 1 was prepared by combining conventional polyamide 6,6 with 30 wt% glass fiber and a heat resistant material. There was a covalent bond between the amide functionality present at the end of the polyamide and the glass fiber whose surface was treated with a silane coupling agent.

  The polyamide resin composition of Example 1 was prepared by adding sodium aluminate silicate to the composition of Comparative Example 1, and thus has the function of trapping cationic ions that have penetrated into the chain, and is resistant to antifreeze and initial. Only chloride resistance can be selectively improved without degrading physical properties.

  The polyamide resin composition of Example 2 was prepared by adding a modified polyolefin to the composition of Example 1, with slightly lower initial physical properties and antifreeze solution than that of the composition of Example 1. However, it showed much better chloride resistance.

Figure 1 is a FT-IR chart of the polyamide resin composition according to Example 2 of the present invention, the characteristic peaks due to intrinsic structure of the silicate capable of ion exchange in the vicinity of 1750 cm ^-1 and 630 cm ^-1, and typically A simple Si—O ₂ peak is shown around 1000 cm ⁻¹ .

  The polyamide resin composition of Example 3 was prepared by adding polyphenylene sulfide to the composition of Example 2 and exhibited the best initial physical properties, antifreeze resistance and chloride resistance.

Figure 2 is a FT-IR chart of the polyamide resin composition prepared according to Example 3 of the present invention, from those of Example 2 the intrinsic peak of contrast polyolefin around 580 cm ^-1 and 460 cm ^-1 Indicated.

  The polyamide resin composition of Example 4 is prepared by adding polyamide 6,10 to the composition of Example 2, and has relatively lower initial physical properties and antifreeze resistance than that of the composition of Example 2. However, it showed better chloride resistance.

Figure 3 is a FT-IR chart of the polyamide resin composition according to Example 4 of the present invention, showing the peak of the polyphenylene sulfide around 810 cm ^-1 and 1200 cm ^-1.

  The polyamide resin composition of Example 5 was prepared by adding polyolefin to the composition of Example 2. This sample did not show very high antifreeze resistance, but showed significantly higher chloride resistance compared to that of Example 2.

  The polyamide resin composition of Example 6 is prepared by adding polyamide 6,36 to the composition of Example 2 and has a relatively lower antifreeze resistance than that of the composition of Example 2, but Better chloride resistance was exhibited.

  The polyamide resin composition of Example 7 was prepared by adding 10% by weight of polyamide 6,12 to the composition of Example 2 and had slightly lower initial physical properties and resistance than that of the composition of Example 2. Although it has antifreeze properties, it showed better chloride resistance.

  The polyamide resin composition of Example 8 was prepared by adding 10% by weight of polyamide 6,12 to the composition of Example 7, and had slightly lower initial physical properties and antifreeze resistance than the composition of Example 7. However, it showed better chloride resistance.

  The polyamide resin composition of Example 9 is prepared by adding 10% by weight of polyamide 6,36 to the composition of Example 6 and has a relatively lower antifreeze resistance than the composition of Example 6, However, it showed better chloride resistance.

  The polyamide resin composition of Example 10 was prepared by adding 10% by weight of polyamide 6,10 to the composition of Example 4, slightly lower initial physical properties and antifreeze resistance than the composition of Example 4. However, it showed better chloride resistance.

  The polyamide resin composition of Example 11 was prepared by adding 10% by weight of sodium aluminate silicate to the composition of Comparative Example 1, and thus has the function of trapping cationic ions that have penetrated into the chain, Including the improvement of antifreeze and initial physical properties, only chloride resistance can be selectively improved.

  The polyamide resin composition of Example 12 was prepared by adding 10% by weight of polyphenylene sulfide to the composition of Example 3 and had better initial physical properties, antifreeze resistance and chlorination resistance than the composition of Example 3. The physical properties were shown.

  As explained above, the polyamide resin composition according to the present invention has much better mechanical and physical properties and antifreeze resistance than those of the conventional polyamide resin composition, and almost the same as the conventional polyamide resin composition. Has equivalent chloride resistance. Therefore, the composition according to the present invention can be applied to various internal and external parts such as boilers and automobile radiator tank caps which generally require heat resistance and rigidity.

It is a FT-IR chart of the polyamide resin composition according to Example 2 of the present invention. It is a FT-IR chart of the polyamide resin composition according to Example 3 of the present invention. It is a FT-IR chart of the polyamide resin composition according to Example 4 of the present invention.

Claims (8)

  A polyamide resin composition having good heat resistance and high chemical resistance, comprising 30 to 80% by weight of polyamide, 10 to 50% by weight of reinforcing agent and 0.1 to 20% by weight of sodium aluminate silicate.   A polyamide produced from polyamide 6, polyamide 6,6, polyamide 6,10, polyamide 11, polyamide 12, polyamide 6,12, polyamide 6,36, polyamide copolymer, aliphatic polyamide, terephthalic acid or isophthalic acid, The composition of claim 1 selected from the group consisting of aromatic polyamides and combinations thereof.   The composition of claim 1, wherein the reinforcing agent is selected from the group consisting of glass fibers, inorganic fillers, and combinations thereof.   Furthermore, the composition of Claim 1 or 2 which contains 1-30 parts (phr) of polyolefin per 100 parts of resin.   Furthermore, the composition of Claim 1 or 2 which contains 1-30 parts (phr) of polyphenylene sulfide per 100 parts of resin.   The composition according to claim 1 or 2, further comprising 1 to 10% by weight of a polyolefin modified with maleic anhydride. Used in the manufacture of components of the cooling system for the cooling water circulation composition according to claim 1 or 2. Used in the manufacture of parts of vehicles, composition according to claim 1 or 2.