JP2003003064A - Polyamide resin composition and molding of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyamide resin composition durable to a high temperature for a short period of time, which, as a molding material for parts that generate frictional heat, electronic instruments parts that come into contact with a solder temporarily and the like, can replace metals and thermosetting resins and can give moldings having good surface appearance. SOLUTION: The composition incorporates 100-250 pts.wt. of aluminum borate whiskers in 100 pts.wt. of the polyamide resin obtained from a mixed xylylenediamine consisting of 15-45 mol.% of p-xylylenediamine and 85-55 mol.% of m-xylylenediamine and an α,ω-linear aliphatic dibasic acid.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polyamide resin composition. In particular, the present invention relates to a polyamide resin composition for molding, which is suitable for applications in which it is brought into contact with a high-temperature object or fluid for a short period of time, or applications requiring solder resistance.

[0002]

2. Description of the Related Art Polyamide resin has impact resistance, abrasion resistance, and
It has been widely used in the fields of automobile parts, electrical parts, OA equipment parts, etc. as engineering plastics with excellent mechanical strength such as abrasion resistance, heat resistance, oil resistance, etc. ing.

Polyamide resin includes, for example, nylon 6,
Many types such as nylon 66 are known. Among them, a polyamide resin (hereinafter referred to as MX nylon) obtained from metaxylylenediamine and α, ω-linear aliphatic dibasic acid has higher mechanical strength and elastic modulus than nylon 6 and nylon 66. It is known that it has a low water absorption rate. However, when many thermoplastic resins including MX nylon are used for screws, nut worms, etc., they are deformed or welded due to the melting of the screw tips due to frictional heat, resulting in loss or destruction of screw functions. I couldn't do it.

Further, it is necessary to use a solder heat-resistant resin for parts that come into contact with solder, such as OA equipment parts.
Resins having solder heat resistance are generally high in melting point and expensive, and few have good surface appearance. By the way, once the assembly process is completed, such parts that may accidentally come into contact with solder during assembly work do not need such heat resistance. Therefore, even a resin having no direct resistance to solder such as MX nylon can be used for such an application if it can withstand a high temperature for a short time.
If MX nylon can be used in place of the solder heat resistant resin, it becomes possible to obtain a cheaper molded product having a good surface appearance, and also improve the mass productivity during molding.

Conventionally, as a means for improving the performance of polyamide resins, it has been proposed to blend other resins and fillers. For example, JP-A-2-55761 proposes a composition in which a polyamide resin is mixed with aluminum borate whiskers, and it is described that a molded product having high strength and high elasticity can be obtained by adding a small amount thereof. In this publication, nylon 6, nylon 66, nylon 610 and the like are listed as the polyamide resin, but there is no description about MX nylon.

JP-A-3-182554 discloses that 100 parts by weight of MX nylon and aluminum borate whiskers 5 to 70 are used.
An invention relating to a molding composition containing parts by weight has been proposed. The invention is known as MX for precision machine parts.
The drawback of a composition in which potassium titanate fibers are blended with nylon resulting in a decrease in mechanical strength and elastic modulus due to moisture absorption is improved by blending aluminum borate whiskers in place of potassium titanate.

Japanese Unexamined Patent Publication (Kokai) No. 4-268373 proposes an invention relating to a polyamide resin composition in which 100 parts by weight of a polyamide resin is mixed with more than 100 parts by weight of aluminum borate whiskers and not more than 250 parts by weight. It is described that the composition of the present invention has high strength, high rigidity, good appearance, and a molded product having small deformation such as molding shrinkage and warpage. A polyamide resin to be used is selected from various diamine components. Although the resulting polyamide resin is mentioned,
Only Nylon 6 has been confirmed to have that effect.

In Japanese Patent Laid-Open No. 7-41669, a crystal nucleating agent is added to a polyamide resin obtained from a mixed xylylenediamine composed of paraxylylenediamine and metaxylylenediamine and an α, ω-straight chain aliphatic dibasic acid. An invention relating to a blended polyamide resin composition is disclosed. The composition of the present invention is said to have excellent moldability and heat resistance, and it is described that glass fibers, potassium titanate, calcium sulfate whiskers, and other fillers can be blended, but aluminum borate whiskers are described. It has not been.

[0009]

The present invention can be used for parts such as screws and nuts which are accompanied by frictional heat, and OA equipment parts which may be in contact with solder temporarily, in other words, for a short time. It is an object of the present invention to provide a polyamide resin composition which can withstand high temperatures and can give a molded product having high strength and good appearance.

[0010]

Means for Solving the Problems The present inventor has conducted extensive studies to solve the above problems, and has found that such objects can be achieved by improving the melting point, heat conduction performance and strength of the resin. The present invention has been reached by selecting the type and blending amount of the resin and inorganic filler therefor. That is, the gist of the present invention is that para-xylylenediamine 15 to 45 mol%
And 100 parts by weight of a polyamide resin obtained from a mixed xylylenediamine consisting of 85 to 55 mol% of meta-xylylenediamine and an α, ω-linear aliphatic dibasic acid,
The polyamide resin composition comprises 100 to 250 parts by weight of aluminum borate whiskers.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. The polyamide resin used in the present invention comprises a mixed xylylenediamine containing metaxylylenediamine and paraxylylenediamine in a specific ratio, and an α, ω-linear aliphatic dibasic acid having 6 to 12 carbon atoms. It is a polyamide resin obtained (hereinafter referred to as "MP nylon"). The amount of para-xylylenediamine in xylylenediamine is 15-
It is 45 mol%, preferably 25 to 40 mol%. When the amount of paraxylylenediamine is less than 15 mol%, the melting point is not sufficiently improved, and specifically, the heat distortion temperature is lowered, and when it exceeds 45 mol%, the melting point becomes too high, which may occur during polymerization and It is not preferable because it may cause inconvenience such as heat deterioration during molding. The amount of meta-xylylenediamine is 85
˜55 mol%, preferably 75 to 60 mol%. Examples of the α, ω-linear aliphatic dibasic acid having 6 to 12 carbon atoms to be reacted with these diamines include adipic acid, sebacic acid,
Examples thereof include suberic acid, dodecanedioic acid and eicodioic acid, with adipic acid being preferred.

The aluminum borate whiskers used in the composition of the present invention are typically 9Al ₂ O ₃ .2B ₂ O.
Has a composition represented by ₃ or _{2Al 2 O 3 · B 2 O} 3, an average fiber diameter of 0.05 to 5 [mu] m, and an average fiber length of white needle-like crystals having the shape of 2 to 100 m.
The shape of the aluminum borate whiskers is selected according to the shape of the desired molded product, but preferably the shape before compounding is an average fiber diameter of 0.5 to 1.5 μm and an average fiber length of 10 to 30 μm. Is. The aluminum borate whiskers are preferably surface-treated with a coupling agent to improve the wettability and bondability of the matrix with the polyamide resin.

As the coupling agent, known ones such as silicon type, titanium type, aluminum type and zirconium type can be used, and a known method can be applied to the method of surface treatment with the coupling agent. Further, aluminum borate whiskers which have been surface-treated with a coupling agent in advance may be blended with the polyamide resin, or the coupling agent may be added at the same time when the whiskers are blended with MP nylon.

The blending amount of aluminum borate whiskers is 100 to 25 with respect to 100 parts by weight of the polyamide resin.
0 parts by weight. If the amount of the aluminum borate whiskers is too large, the strength and the appearance will be deteriorated, and if it is too small, the strength and the rigidity will be insufficient.
It is from 00 to 220 parts by weight.

In addition to MP nylon and aluminum borate whiskers, the composition of the present invention preferably further contains some inorganic nucleating agent. As an inorganic nucleating agent,
Known materials can be used, and examples thereof include talc, calcium carbonate, boron nitride and the like, but the material is not particularly limited thereto. In addition to the above, the composition of the present invention may also contain a flame retardant, a colorant, a plasticizer, a stabilizer, an antioxidant, an ultraviolet absorber, an antistatic agent, etc., which are usually added to polyamide resins. .

The polyamide resin composition of the present invention thus obtained can give a molded product which is excellent in heat resistance for a short period of time and has high strength and excellent appearance. That is, the polyamide resin (MP nylon) of the present invention containing paraxylylenediamine as a structural unit has a higher melting point and is more resistant to melting by heat than MX nylon. In addition, aluminum borate whiskers have a high filling amount (50% in the composition).
Since it is contained in an amount of (% by weight or more), it has high strength, high thermal conductivity, and excellent diffusion of frictional heat. as a result,
The polyamide resin composition of the present invention greatly improves the resistance to high temperature for a short time.

Generally, the general diameter of glass fiber or carbon fiber used to reinforce the strength of resin is 6 to 13 μm.
Since the length is about m and the length is generally about 200 to 600 μm, it is impossible to effectively reinforce the roots of small gear threads and screw threads. On the other hand, the aluminum borate whiskers used in the composition of the present invention have a small fiber diameter and a short fiber diameter, so that they have a high reinforcing effect on small molded articles. In particular, a whisker having a fiber diameter of 1.5 μm or less can be filled up to a small screw having a small diameter and a small screw thread, or even the tip of a gear, so that such a molded product is effectively reinforced. When the same small-diameter gear is molded with the glass fiber reinforced material and the whisker reinforced material, even if the glass reinforced is superior in tensile strength and bending strength, the whisker reinforced gear may be superior in strength.

In applications requiring slidability, there is a limit PV value for expressing the friction coefficient, the wear rate and the height of the worst condition as sliding characteristics. The limit PV value represents the product of pressure (P) and velocity (V) applied when two materials rub, and the amount of heat finally generated by friction causes the resin to melt and become unusable. It is preferable that the number is large and represents the condition. In addition to the frictional characteristics between the material and the mating material, melting point, specific heat and thermal conductivity are related. Further, since the limit PV value changes depending on the speed and pressure, it is necessary to compare under the condition that either speed or pressure is fixed. Pressure during sliding test is kgf / cm
^{2. If} the speed is expressed in cm / s, the limit PV value is kgf / c
It is represented by m · s. The composition of the present invention has a relatively large PV value and is suitable as a sliding material.

A molded article using the composition of the present invention is considered to be used in contact with a molded article which becomes high in a relatively short time. For example, it can be applied to screw blades, brake shoes or peripheral parts, contact parts of grips of high-temperature heating elements, resin products that contact solder, etc. Around the brake, O
Parts of A product such as screws, nuts, worms, etc. that are accompanied by frictional heat,
Examples include solder contact parts.

[0020]

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples as long as the gist thereof is not exceeded. The materials, molding conditions and test methods used in the following examples are as follows.

[Materials] MP6: A polyamide resin produced by reacting mixed xylylenediamine (30 mol% para-xylylenediamine and 70 mol% meta-xylylenediamine) with adipic acid. Melting point 258 ° C, relative viscosity (96% sulfuric acid solution 1 g / 1
(00 ml) was 2.08. The method for producing the resin was in accordance with the method of Example 1 of JP-A-7-41669. MXD6: Polyamide MXD6 # 6000 (trade name, manufactured by Mitsubishi Gas Chemical Co., Inc., a polyamide resin produced from metaxylylenediamine and adipic acid). Melting point 243 ° C, relative viscosity 2.14.

PA66: Zytel 101 (trade name,
DuPont Polyamide 66) Aluminum borate whiskers: Arbolex YS3
A (trade name, manufactured by Shikoku Chemicals Co., Ltd., aminosilane-treated product). Talc: Micron White 5000A (trade name, manufactured by Hayashi Kasei). Glass fiber: CS03JAFT-2 (trade name, manufactured by Asahi Fiber Glass, φ10μ chopped strand)

[Molding conditions] 1 for each test piece and ring
Molding was performed under the following conditions using a molding machine with a 00 ton cylinder and a diameter of 36 mm. Injection molding machine set temperature: Uniformly 270 ° C, mold temperature 130
C. Injection pressure: 1200 kgf / cm ² Injection rate: It was adjusted so that the time until VP switching was about 1 second. VP switching: The ring and the tensile test piece were held about 5 mm before the final filling amount and the holding pressure was held at 600 kgf / cm ² for 12 seconds. Bolt molded product is about 10mm for final filling
The holding pressure was 800 kgf / cm ² for 20 seconds.

[Measurement conditions] Bending test: A 6.4 × 12.6 × 126 mm plate-shaped injection-molded article was used as a test piece, and the bending strength and bending elastic modulus were measured based on the test method of ASTM D790. Limit PV value: Ring for Suzuki sliding test (outer diameter 26 mm,
Inner diameter: 20 mm, thickness: 3 mm, width: 15.3 mm), and the end surface of a ring made of carbon steel S45C with the same dimensions as a mating material with a Suzuki sliding tester was rubbed with the surface treated with emery polishing # 1200. A dynamic test was conducted. Sliding speed 10 cm / s
Then, if kept for 1 minute, the surface pressure is increased, and the surface pressure immediately before the surface load at which the ring begins to melt by heat is multiplied by the speed to obtain the limit PV value. The ring attachment is not insulated with carbon steel, so the heat is dissipated.

Heat transfer test: thickness 1/8 inch, diameter 4
An inch disk is molded and conditioned in a constant temperature and humidity room of 23.5 ° C and 50% for 24 hours, then placed on a hot plate adjusted to 60 ° C and the surface temperature after 10 seconds and 20 seconds is non-contact. It measured with the infrared radiation thermometer (Tasco Japan THI500S). Since the heat radiation from the surface increases with a long time, it was ignored for a longer time.

Solder heat resistance test: Solder was dissolved in a solder bath and kept at 260 ° C. An ASTM tensile test specimen (extra-dry t = 3.2 mm) was used to submerge approximately 40 mm vertically.
After immersion for 15 seconds, the test piece was immediately pulled up and observed, and when there was no deformation or significant change in the surface due to softening, it was marked with ◯, when it was slightly modified, it was marked with Δ, and when it was significantly modified, it was marked with x. Floating refers to a phenomenon in which the softened resin is deformed on the surface and floats because the density of the solder melt is high. Good results are obtained when the heat transfer to the inside is high, but since the solder bath has a melting point or higher, any test piece melts when the heat transfer reaches the inside.

Deflection temperature under load: A test piece similar to the bending test was molded, and a load of 1 was applied according to the test method of ASTM D648.
It was measured at 8.6 MPa. Examples 1 and 2 and Comparative Examples 1 to 3 Polyamide resin, aluminum borate whiskers and talc (nucleating agent) were blended in a tumbler with the composition shown in Table 1 below, and a twin-screw extruder TEM35B manufactured by Toshiba Machine Co., Ltd.
Was added from the root and melt-extruded to produce a resin composition. When glass fibers were used, the composition was produced by melting and extruding in the same manner as above except that the glass fibers were side-fed after melting. The temperature was set to 280 ° C. up to the side feed and 260 ° C. from the side feed part. A test piece was molded using the obtained composition, and the performance was tested.
The results are shown in Table 1.

[0028]

[Table 1]

[0029]

As is clear from the examples and comparative examples, M
The polyamide resin composition of the present invention in which P nylon and aluminum borate whiskers are blended in a specific ratio has a limit PV
It can be seen that the value and the heat transfer coefficient are increasing. From this fact, even if the temperature rises rapidly, it is possible to withstand the short-term use under more severe conditions by transmitting the heat generated at that time to the outside, and by selecting the temperature and contact time It also shows resistance to. By using the composition of the present invention which can be molded with a relatively low melting point, in the field where a metal, or a thermosetting resin or a thermoplastic resin having a higher melting point is conventionally used in a portion contacting a high temperature for a short time. Therefore, it is possible to obtain a product that has good mass productivity during molding.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4F071 AA55 AB21 AB26 AB27 AD01                       AD02 AE17 AE22 AF45 AH12                       AH17 BA01 BB05 BC04 BC07                       BC17                 4J002 CL031 DE237 DJ047 DK006                       DK007 FA066 FB086 FB096                       FB166 FD016 FD207 GQ00                       GT00

Claims (7)

[Claims] 1. A polyamide resin obtained from 100% by weight of a mixed xylylenediamine consisting of 15 to 45 mol% of paraxylylenediamine and 85 to 55 mol% of metaxylylenediamine and an α, ω-linear aliphatic dibasic acid. A polyamide resin composition obtained by mixing 100 to 250 parts by weight of aluminum borate whiskers with respect to parts. 2. The polyamide resin composition according to claim 1, wherein the α, ω-linear aliphatic dibasic acid is adipic acid. 3. The polyamide resin composition according to claim 1, wherein the aluminum borate whiskers are treated with a coupling agent. 4. The aluminum borate whiskers have an average diameter of 0.5 to 1.5 μm and an average fiber length of 10 to 30.
The polyamide resin composition according to claim 1, wherein the polyamide resin composition has a thickness of μm. 5. The polyamide resin composition according to claim 1, further comprising an inorganic nucleating agent. 6. The polyamide resin composition according to claim 1, wherein the inorganic nucleating agent is talc. 7. A molded product using the polyamide resin composition according to any one of claims 1 to 6.