JPH02255764A - Method for preventing warpage of crystalline polyamide molded article - Google Patents

Abstract

PURPOSE:To prevent the warpage of a molded article composed of a crystalline polyamide and a fibrous reinforcing material, without lowering the heat- resistance, rigidity and impact strength of the molded article, by adding a specific amount of a specific amorphous copolymerized polyamide to the resin composition. CONSTITUTION:A molded article free from warpage is produced by mixing (A) a crystalline polyamide (e.g. nylon 6 or nylon 46) with (B) a fibrous reinforcing material having an aspect ratio of preferably >=5 (e.g. glass fiber) and (C) 3-40wt.% of an amorphous copolymerized polyamide derived from 50-10mol% of isophthalic acid, 0-40mol% of terephthalic acid, 45-5mol% of hexamethylenediamine and 5-45mol% of bis(4-amino-3-methylcyclohexyl)methane and preferably having a glass transition temperature of >=100 deg.C and a relative viscosity of 1.2-3, thoroughly mixing the components with a twin-screw extruder, etc., under melting and molding the obtained resin composition.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for preventing warpage of a molded article made of crystalline polyamide and fibrous reinforcement.

(Prior art) Molded products made of crystalline polyamide, typified by nylon 6 and nylon 66, and fibrous reinforcement have excellent heat resistance and rigidity, and are widely used mainly in the electrical, electronic, and automobile fields. .

However, molded products made of such crystalline polyamide and fibrous reinforcement tend to exhibit anisotropy in dimensional stability and mechanical properties, and large warps often occur in molded products formed by injection molding etc. Something happened.

The following is a method for preventing warping of such molded products.

Filled with granular inorganic fillers with a small aspect ratio (ratio of length to diameter)! There are known ways to do this. However, such a method is not only not very effective, but also has problems in that the specific gravity of the molded product increases and the Izot impact strength decreases.

(Problems to be Solved by the Invention) Therefore, one object of the present invention is to effectively prevent warping of molded products made of crystalline polyamide and fibrous reinforcement without causing a decrease in heat resistance, rigidity, or impact strength. The goal is to prevent this from happening.

(Means for Solving the Problems) As a result of extensive research in order to solve the above problems, the present inventors have found that by making a specific amount of a specific amorphous copolyamide exist, all of the objects of the present invention can be achieved. The present invention was achieved by discovering the following.

That is, the present invention uses 50% isophthalic acid when producing a molded product made of crystalline polyamide and fibrous reinforcement.
~10 mol%, terephthal SO 0~40 mol%, hexamethylenediamine 45~5 mol%, bis(4-amino-3
The subject matter is a method for preventing warping of crystalline polyamide molded products, which is characterized by the presence of 3 to 40% of an amorphous copolymerized polyamide obtained from 5 to 45 moles of methylcyclohexyl)methane. .

According to the method of the present invention, the heat resistance and rigidity of the molded product can be improved.

It is truly surprising that not only is warpage effectively prevented without a decrease in impact strength, changes in dimensions and physical properties due to water absorption are also suppressed, and the gloss of the molded product surface is greatly improved. That's true.

The crystalline polyamide in the present invention means that when the culm temperature is 1 m at 20°C/min using a commonly used DSC device,
An amorphous copolymer polyamide refers to one that exhibits a heat of fusion of 1 cal/g or more.

Specific examples of the crystalline polyamide used in the present invention include nylon 6, nylon 66, nylon 46. Nylon 11. Nylon 12. nylon 610 nylon 6
6/6I (copolymer of hexamethylene adipamide and hexamethylene isophthalamide), nylon 66/6T (
Examples include nylon 6T/61 (a copolymer of hexamethylene adipamide and hexamethylene terephthalamide) and nylon 6T/61 (a copolymer of hexamethylene terephthalamide and hexamethylene isophthalamide).

It is not limited to these. It was a cow. These polyamides may be further copolymerized with other components as long as crystallinity is not affected. These crystalline polyamides can be obtained by a combination of a known melt polymerization method or an in-phase polymerization method.

The amorphous copolyamide used in the present invention is:

Isophthalic acid 50-10 mol% and terephthalic acid 0-40
mol% and hexamethylene diamine 45-5 mol% and bis(4-amino-3-methylcyclohexyl)methane 5-5 mol%
This is what you get from 45 moles of envy.

Among these, the mol% of bis(4-amino-3-methylcyclohexyl)methane has a large influence on the glass transition temperature of the resulting copolyamide.

If the amount of bis(4-amino-3-methylcyclohexyl)methane is less than 5 mol%, the glass transition temperature will be too low, making it undesirable as a component of the resin composition of the present invention. Also, bis(4-amino-3-methylcyclohexyl)methane is
If it exceeds 5 mol%, the glass transition temperature becomes too high and
This may cause problems when producing the resin composition of the present invention.

The amorphous copolyamide used in the present invention is:

Manufactured by a known method. For example, special public relations
As in the method of Japanese Patent No. 1024, it is common to first react a diamine component and a dicarboxylic acid component in water to first generate a salt, and then perform polycondensation while condensing the salt. The salt solution is preferably first prepolymerized in a closed autoclave at a temperature ranging from 200° C. to 350° C. under reaction pressure, and then the pressure is released and the reaction is allowed to proceed under atmospheric or reduced pressure until the polycondensation reaches equilibrium. conduct.

The amorphous copolyamide used in the present invention preferably has a glass transition temperature of 100° C. or higher so that the heat resistance of the molded product obtained does not exceed tN. Glass transition temperature can be measured with a general SC device. In addition, in order to obtain good physical properties, the relative viscosity change of the amorphous copolyamide (20°C, in rn-cresol, 1t</dj
l! ) is preferably in the range of 1.2 to 3.0.

Specific examples of the fibrous reinforcement used in the present invention include glass fiber, carbon fiber, aramid fiber, silicon carbide fiber,
Potassium titanate fiber, boron nitride fiber or other organic fiber, inorganic fiber.

Examples include metal fibers. Although the aspect ratio of the fibrous reinforcement is not particularly limited, a value of 5 or more is preferably used for boat fishing because it has a large effect of improving the strong shore and elastic modulus. It is also possible to use two or more of these fibrous reinforcements in combination, and other fillers such as kaolin, talc, mica, wollastonite calcium carbonate,
Glass beads, graphite, etc. may be used in combination.

The blending ratio of the crystalline polyamide and the In-like reinforcement is arbitrary. Generally, the fibrous reinforcement is blended in a weight ratio of 1/100 to 80/100 to the crystalline polyamide, but is not particularly limited to this range.

In order to achieve the effects of the present invention, the amount of amorphous copolyamide present in the molded product consisting of crystalline polyamide and fibrous reinforcement may be within the range of 3 to 40% by weight of the total. Preferably. If the composition ratio of the amorphous copolyamide is lower than this, the warpage prevention effect of the molded product will not be significant and changes in dimensions and physical properties due to water absorption will not be effectively restricted. Also, the composition of the amorphous copolyamide If the ratio is higher than this ratio, changes in dimensions and physical properties due to warping and water absorption are effectively suppressed, but the heat resistance as indicated by thermal deformation temperature change decreases and the heat shrinkage rate also increases, which is not preferable.

In the present invention, the method for blending the amorphous copolyamide into a molded article consisting of crystalline polyamide and fibrous reinforcement is to physically mix these components and then to Although it is common practice to thoroughly mix the amorphous copolyamide with the crystalline polyamide in the molten state using a frame or other equipment, it is common to mix the amorphous copolyamide with the crystalline polyamide! Any method may be used as long as it can be effectively mixed and dispersed into the molded article comprising the igs-like reinforcement.

In the method of the present invention, depending on the purpose of the molded article, heat stabilizers, antioxidants, light stabilizers, lubricant pigments, flame retardants,
Additives such as plasticizers may also be added.

(Reference Example) Amorphous copolymer polyamide (hereinafter referred to as PA-1) 40 mol% of isophthalic acid, 10 mol% of terephthalic acid.

10 kg of these raw materials were charged into a reaction tank together with 5 kg of pure water at a ratio of 35 mol y of hexamethylene diamine and 15 mol % of bis(4-amino-3-methylcyclohexyl)methane, and the inside of the reaction tank was purged several times with nitrogen. The air was purged. After raising the temperature of the reactor to 90°C and stirring for about 5 hours, the temperature of one reaction was gradually raised to 280°C under pressure (18 bar) over 10 hours. Then, the pressure is released and the pressure is lowered to atmospheric pressure.

Further, polycondensation was carried out for 6 hours at the same temperature change. After the reaction is complete,
The amorphous copolyamide 4' was discharged from the reaction vessel and cut to obtain pellets.

Relative viscosity of the obtained pellet (same measurement method as in the previous i)
was 1.50. In addition, the glass transition change is 150°
It was C.

(Example) Examples 1 to 3. Comparative Examples 1 to 3 Nylon 6 (manufactured by Unitika, A1030 mouth R1,), nylon 66 (T (manufactured by 4-layer, Maranyl 100), nylon 46 (manufactured by Unitika, F5000), amorphous Kyoeisha polyamide PA =1 and glass fiber (manufactured by Asahi Fiber Glass Co., Ltd.).

Three-open chopped strands Nα, 429) were blended in the proportions shown in Table 1 and melt-mixed in a 22-piece extruder at the temperature shown in Table 1 to obtain pellets.

The resulting pellet was vacuum dried at 110°C for 16 hours.

After that, molding was performed under the same conditions listed in Table 1.

Various test pieces were obtained. Melting point, heat resistance, rigidity, impact resistance, and warping of these test pieces.

Dimensional changes due to water absorption, rigidity changes due to water absorption, and gloss of the molded product surface were evaluated. The results are shown in Table 2. The evaluation methods were as follows.

20°C/min using scatter point nsc! ￥ Horse Speed Boost? '
4 and determined from the endothermic peak.

Salmon performance under heavy load (IF!, 6 based on ASTM 0641)
Thermal deformation temperature was measured in Kg/i).

! sex Flexural modulus was measured based on ASTM 0790.

Izotsu impact strength with a notch was determined based on ASTM D256.

A disk with a thickness of 1.6 ua (if PiooIIIw c7) was molded, and the maximum displacement height caused by warping was determined by placing it on a horizontal table. If there is no warpage, it will be 0.

The next day, Mizutaka Keiwa Tozoku! ■ Thickness 3.2+uw, Radius 12.511Lm, Length 12
A test piece of 5 s+m was immersed in water at 50° C. for 24 hours, and the dimensional change in the length direction during that time was determined.

Tamamizu Genmotoe! Made! The flexural modulus of elasticity was measured after being immersed in 50'C water for 24 hours and expressed as a percentage decrease relative to that before treatment.

luster By visual inspection of the surface of the molded product.

○: Good 5 △: Slightly poor, ×: Poor harvest (effects of the invention) According to the method of the present invention, a molded product made of crystalline polyamide, amorphous polyamide and fibrous reinforcement has heat resistance,
It is clear that warping is effectively prevented without decreasing rigidity or impact strength, and the surface gloss and impact strength of the molded product are greatly improved.

Patent applicant Unisenriki Co., Ltd.

Claims (1)

[Claims] (1) In producing a molded article consisting of crystalline polyamide and fibrous reinforcement, 50 to 10 mol% of isophthalic acid
and 3 to 40% by weight of an amorphous copolymer polyamide obtained from 0 to 40 mol% of terephthalic acid, 45 to 5 mol% of hexamethylene diamine, and 5 to 45 mol% of bis(4-amino-3methylcyclohexyl)methane. A method for preventing warpage of crystalline polyamide molded products, which is characterized by causing warpage to occur.