WO2004022632A1

WO2004022632A1 - Method for producing polyamide resin composition excellent in durability at high temperature

Info

Publication number: WO2004022632A1
Application number: PCT/JP2003/011159
Authority: WO
Inventors: Nori Yoshihara; Hideki Eguchi
Original assignee: Toyo Boseki Kabushiki Kaisha
Priority date: 2002-09-02
Filing date: 2003-09-01
Publication date: 2004-03-18
Also published as: JP4235878B2; JP2004091707A; AU2003261873A1

Abstract

A method for producing a heat-resistant polyamide resin composition, which comprises dissolving a copper compound, as a thermal stability, in caprolactam and then incorporating the resultant solution into a polyamide resin, or comprises dissolving a copper compound in caprolactam, adding water to the resultant solution, to prepare an aqueous solution, and then incorporating the aqueous solution into a polyamide resin. The method allows the dispersion of the copper compound into the polyamide resin at the level of a molecule, which leads to the prevention of variation in durability performance capability among respective formed products or among respective portions of a formed product.

Description

Specification

Method for producing polyamide resin composition having excellent high-temperature durability

Technical field

The present invention relates to a method for producing a heat-resistant polyamide resin used for automobiles, electric appliances, and office equipment. The polyamide resin composition produced according to the present invention has a small variation in quality durability, and a highly reliable molded product can be obtained.

Background art

Conventionally, amines, phenols and copper compounds have been published as heat resistance improvers for polyamide shelf. Among them, copper compounds are effective as a thermo-oxidative degradation inhibitor and a photo-oxidative degradation agent for polyamide resins, and are known to be particularly effective at a high temperature of 150 ° C. or higher. (For example, JP-A-6-263988) In order for a copper compound to effectively act as a heat resistance improver, the copper compound must be highly dispersed in the polyamide and coordinated to an amide group. It is considered necessary. However, since copper compounds are generally solid, it is extremely difficult to uniformly disperse a small amount of copper compounds in a polyamide resin as a heat resistance improver in the compounding process, and copper compounds are highly dispersed in polyamide. Because of this, durability characteristics such as strength vary depending on the molded product or the parts of the molded product.Particularly, molded products with thin parts of 1 mm or less, very small parts of several g or less, and surface There is a problem that the reliability of the heat resistance improving effect of appearance parts that require resin properties is low. In order to solve this problem, there have been taken a method of adding the copper compound after finely pulverizing it, and a method of adding the copper compound in a larger amount than necessary. (For example, Japanese Patent Application Laid-Open No. Hei 6-263988) However, the method of pulverizing or blending in a large amount was a problematic method because the copper conjugate was harmful. On the other hand, in recent years, parts have become lighter and thinner, and there has been a demand for a material having high reliability in terms of the durability performance of fine parts and molded products, and a polyamide composition with small variations in quality and durability has been demanded. For this reason, there has been proposed a method and a polya method in which an aqueous solution of a copper compound and an aqueous solution of an inorganic octogenate are mixed and added to generate copper octogenide on the surface of a polyamide resin and then to perform a drying treatment. In addition, it is preferable to perform aging before permeating the aqueous solution into the polyamide resin before drying. A law has been proposed. (Japanese Unexamined Patent Publication No. Hei 6-2566449, Japanese Patent No. 3926140)

In the method of mixing and adding the aqueous solution of the copper conjugate and the aqueous solution of the inorganic halogen compound and attaching them to the surface of the polyamide shelf and drying or aging before drying, the dispersibility is slightly improved. . However, it is concentrated on the surface as it dries and becomes difficult to diffuse. In addition, after being diffused inside, it is predominantly pre-coated on the surface of the polyamide resin together with moisture by drying or aging, and is precipitated only on the surface of the polyamide resin. Sufficient uniform dispersion cannot be obtained. Even in this method, in the case of molded products that become precision parts or appearance parts where the resin properties of the surface layer are important, variations in durability performance at high temperatures for each molded product or each part of the molded product may be a problem was there.

DISCLOSURE OF THE INVENTION '' The present invention is to produce a polyamide resin composition in which a copper compound is uniformly dispersed in a polyamide resin in a compounding step or a molding step, and a highly reliable molded article with a small variation in durability at high temperatures is obtained. That is the task.

The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention. That is, the present invention is a method for producing a heat-resistant polyamide resin composition, which comprises dissolving a copper compound in force prolactam in advance and blending the solution with a polyamide shelf. Further, there is provided a method for producing a heat-resistant polyamide resin, which comprises dissolving a copper compound in force prolactam in advance, adding water to the solution to form an aqueous solution, and blending the aqueous solution with the polyamide resin.

Hereinafter, the present invention will be described specifically.

The polyamide resin in the present invention has an acid amide bond (one C ONH—) in the molecule. Specifically, ε-force prolactam, 6-aminocaproic acid, ω-enantholactam, 7- Polymers or copolymers obtained from aminoaminohepnoic acid, 11-aminoundecanoic acid, 9-aminononanoic acid, α-pyrrolidone, piperidone, etc .: hexamethylenediamine, nonamethylenediamine, pendecamethylenediamine , Dodecamethylenediamine, metaxylylenediamine, etc. Or a polymer or a blend thereof obtained by polycondensing a dicarboxylic acid with a dicarboxylic acid such as terephthalic acid, isophthalic acid, adipic acid, sebacic acid, or the like, but is not limited thereto. Not something.

Among the above polyamide resins, those having an average molecular weight of 900 to 300,000 are preferred. In addition, the amount of amino terminal groups and the number of terminal groups of polyamide resin are large because they react with and bind to the coupling agent of the reinforcing agent and the polymer having a reactive group other than the polyamide resin. Is more preferred. The balance of the amounts of both terminal groups may be changed depending on the type and amount of the coupling agent used and the type and amount of the reactive group of the polymer having a reactive group other than the polyamide resin.

The copper compound used in the present invention includes copper chloride, copper bromide, copper iodide, copper acetate, copper acetyl acetate, copper carbonate, copper borofluoride, copper citrate, copper hydroxide, copper nitrate, Examples thereof include copper sulfate and copper oxalate. In particular, copper chloride, copper bromide, copper iodide, copper acetate, and hydrates thereof having a high decomposition temperature are preferable. The concentration of addition to the polyamide resin depends on the type of the copper compound, but is preferably 0.01 to 0.1 part by weight as a copper atom per 100 parts by weight of the polyamide resin.

The form of the copper compound to be dissolved in advance with force prolactam is preferably in the form of a fine powder, but in the present invention, it is not always necessary to make the powder into a fine powder because it is added after being dissolved in force prolactam in advance. Is also good. This is one of the advantages of the present invention. On the other hand, when a conventional copper compound in a solid state is directly added to a polyamide resin, it must be processed into a fine powder of 5 m or less in order to uniformly disperse the polyamide resin, which poses problems in terms of cost and handling. is there.

The force prolactam used in the present invention is not particularly limited, and industrially produced one can be used.

The water used in the present invention is preferably pure water or distilled water, but is not limited thereto, and general industrial water can also be used.

As a method of dissolving a copper compound into a lactam, a method in which a predetermined amount of a copper compound is added to a molten lactam and mixed and dissolved. The concentration of addition to force prolactam depends on the type of copper compound, but it is 0.1 to 100 parts by weight of force prolactam. ~ 50 parts by weight is preferred. At this time, other stabilizers can be mixed at the same time. As a method of blending a copper compound with a pro-prolactam solution or an aqueous solution of a pro-prolactam in a polyamide resin, a copper-compound-dissolved pro-prolactam solution is maintained in a molten state of 70 or more while preparing a polyamide resin compound. There is a method of adding during molding. After cooling the prolactam solution to 70 ° C or less, it can be pulverized in a solid state and blended when preparing a compound of a polyad resin or at the time of molding.

Hot water of 20 ° C or more can be added to the copper-containing prolactam to form a stable aqueous solution. The melting point of this aqueous solution can be adjusted by the concentration. It is preferable to adjust the melting point to a room temperature or less and to mix it in a liquid state, since it can be uniformly dispersed on the polyamide resin surface. The concentration of the solution is not particularly limited, but is preferably from 10 to 99%, more preferably from 30 to 85%.

When the melting point of the aqueous solution is equal to or higher than room temperature, the object of the present invention can be similarly effectively achieved by heating to a temperature equal to or higher than the melting point and using it for premixing at the time of compounding.

The reason why the present invention can be achieved by dissolving in force prolactam, or by dissolving in force prolactam and water, is not clear, but the fact that the copper conjugate is easily coordinated with force prolactam and molecularly dispersed, It is considered that force prolactam and water are likely to be molecularly dispersed in the polyamide resin, and as a result, the copper compound is likely to be molecularly coordinated with the polyamide resin. The heat-resistant polyamide resin composition produced according to the present invention further includes glass fiber, carbon fiber, whiskers, fibrous reinforcing materials such as aramide fiber and polyphenylene sulfide fiber, talc, clay, silica, wollastonite, Mineral fillers such as calcium carbonate, polyester resins, polyolefins, polyphenylene ether resins, polymers such as ABS transcripts, release agents such as higher fatty acid salts, higher fatty acids, higher fatty acid esters, low molecular weight polyolefins, hindered phenols And heat stabilizers such as thioethers and phosphites, and light stabilizers such as benzophenones, triazoles and hinderedamines. Further, a carbon black pigment or the like can be blended.

The heat-resistant polyamide resin according to the present invention comprises a single-screw extruder, a twin-screw extruder, It is used by melt-kneading using a device such as a kneader, or by spraying on the pellet surface during molding. There are no particular restrictions on the equipment used and kneading conditions. The molding method is not particularly limited, but is generally injection molding or extrusion molding.

BEST MODE FOR CARRYING OUT THE INVENTION

Example

Hereinafter, the present invention will be described specifically with reference to Examples. The evaluation in the specification was measured by the following method.

(1) Flexural strength and fracture strain after heat aging

Using an injection molding machine set at 260 ° C and a TYPE B mold specified in IS〇294-1 whose surface temperature is controlled at 80 ° C, a test piece of 8 OmmX 10 mm x 4 mm Was molded. Twenty of each molded product were randomly picked and aged at 165 ° C for 3000 hours. The treated sample was stored and conditioned in a laboratory desiccator temperature controlled at 23 ° C for 24 hours. Using an all-purpose tensile tester, a bending test was performed in accordance with ISO 178, and the bending strength and the breaking strain were measured. The average value and the standard deviation at 20 points were obtained and compared. The reliability regarding the variation in durability performance was evaluated based on the standard deviation.

(Example 8, Comparative Example:! ~ 5)

A prescribed amount of various copper compounds (Nacalai Tesque Co., Ltd., Reagent Class 1) is added to the stabilizing composition shown in Table 1 in force prolactam temperature-controlled to 80 ° C and melt-mixed with a stirrer. A force prolactam solution of the copper compound was prepared and stored at 80 ° C. Alternatively, 30 parts by weight of hot water at 80 ° C was added to 100 parts by weight of the molten mixture, mixed with a stirrer, and stored in a laboratory at about 25 ° C as an aqueous solution. The above operation was performed in a plastic tank.

65 parts by weight of polyamide 6 resin whose relative viscosity (solvent: 96% sulfuric acid, polymer concentration: 1 g / d 1) measured in a thermostat at 20 ° C is 3.1 or polyamide 66 whose relative viscosity is 3.2 65 parts by weight of resin, 35 parts by weight of talc having an average particle diameter of 4 m, 0.2 parts by weight of lithium iodide, and 0.2 parts by weight of the above copper compound. And pre-mix to about 0.010% by weight. Thereafter, the mixture was put into a hopper of a twin screw extruder of 3 3πιιηφ whose temperature was adjusted to 260, melt-kneaded and extruded to obtain a pellet-like polyamide resin compound.

As a comparative example, an example in which a copper compound was not blended as shown in Table 2 and a copper shelf compound were obtained by directly premixing a copper compound in a powder state without melt-mixing the copper compound with force prolactam.

In Table 1, injection molded articles were obtained from the polyamide resin compound pellets obtained in Examples and Comparative Examples, and the bending strength and rupture strain after the above-mentioned heat aging were measured. The results are shown in Tables 1 and 2. It was shown to.

As is clear from Tables 1 and 2, the variation in flexural strength and breaking strain after heat aging of the molded body of the polyamide resin composition obtained by the method of the present invention in Examples is shown in Comparative Examples 3 to 5. It is extremely small compared to the variation in bending strength and rupture strain after heat aging.

Industrial applicability

ADVANTAGE OF THE INVENTION According to this invention, the copper compound which is a heat stabilizer can be uniformly disperse | distributed to a polyamide resin in a compounding process and a molding process, and the dispersion | variation in the durability performance at high temperature is small, and a highly reliable polyamide resin composition. Can be manufactured. Therefore, it can be suitably used in fields where high reliability is required for durability performance of thin-walled parts such as electronic parts and very small mechanical parts.

Table 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 ε-force prolactam 90 95 90 85 90 90 90 90 Copper chloride (Π) dihydrate 10 5 10 15 10 Stabilizer compound Copper bromide 10

Copper iodide (I) 10

Copper acetate (Π) hydrate 10

Water 30 30 30 30 30 30 30

ΡΑ6 65 65 65 65 65 65 65

Polyamide resin composition ΡΑ66 65 Compound talc 35 35 35 35 35 35 35 35

(Parts by weight) Potassium iodide 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2

Copper compound (copper concentration) 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01

T65 ° O after 3000 hours treatment 73.8 77.3 79.1 77.7 72.2 73.5 71.9 79.1 Flexural strength (MPa) Standard deviation 2.8 2.6 2.3 2.3 2.7 2.6 2.4 2.4

Average value after processing at 165 ° Ο3000 hours 1.32 1.53 1.57 1.49 1.30 1.34 1.28 1.29 Flexural strain (%) Standard deviation 0.28 0.23 0.22 0.27 0.26 0.23 0.28 0.24

Claims

The scope of the claims

1. A method for producing a heat-resistant polyamide resin composition, comprising: dissolving a copper compound in force prolactam beforehand and combining the solution with a polyamide resin.

2. A method for producing a heat-resistant polyamide resin composition, which comprises dissolving a copper compound in force prolactam in advance, adding water to the solution to form an aqueous solution, and blending the aqueous solution with a polyamide resin.