JPH0229458A - Low-warpage polyamide resin composition - Google Patents

Abstract

PURPOSE:To obtain the title composition which can give a molding improved in dimensional stability and mechanical properties without causing deformations such as warpage by adding a fibrous filler to a polyamide resin (mixture) in which a layered silicate has been homogeneously dispersed. CONSTITUTION:100pts.wt. polyamide resin (mixture) (A) comprising at least 80wt.% polyamide resin (A) of an average MW of 9,000-30,000 and at most 20wt.% another polymer (e.g., PP) is mixed with 0.05-15pts.wt. layered silicate (B) of a length of a side of 0.002-1mum and a thickness of 6-20Angstrom (e.g., montmorillonite of a cation exchange capacity of 50-320 milliequivalent/100g), and component B is dispersed in the mixture by melt kneading so that respective sheets of component B are distant form each other by at least 20Angstrom ; and 20-115 pts.wt. fibrous filler (C) of an aspect ratio of 3-70 (e.g., Si3N4 whisker of a fiber diameter of 0.1-3mum) is added to the obtained mixture.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention provides a method for obtaining a molded product that is substantially free from deformation such as warpage and has excellent mechanical properties. The present invention relates to a polyamide resin composition that can be produced.

(Prior Art) Polyamide resin is widely used as an injection molding material for parts of automobiles, electrical appliances, etc. because its molded products have excellent mechanical properties. In order to further expand the scope of use of this polyamide resin, a glass fiber reinforced material based on a polyamide resin has been proposed, which has high rigidity and can maintain high rigidity even at high temperatures (Japanese Patent Laid-Open No. 51-1979-1). Publication No. 50960, JP-A-5
Publication No. 4-18854 and Japanese Unexamined Patent Publication No. 168058/1983
(see publication).

However, when the resin composition described in the above publication is filled only with glass fibers, the molded product has large warpage when molded by injection molding, has low dimensional stability, and the resulting molded product does not meet the requirements. There is a problem in that it is not possible to obtain a device that satisfactorily performs its functions.

In addition, a material has been proposed that is based on polyamide resin and contains glass fiber and powdered inorganic material, which can reduce warping and deformation (see Japanese Patent Publication No. 58-4737 and Japanese Patent Application Laid-open No. 7056-1982). However, as can be seen from the claims, the blending ratio of glass fiber is 15 or 10% by weight or less and the amount of inorganic substances other than glass fiber is 30 or 20% by weight or more. Adding this much inorganic material to a small amount of material deteriorates the excellent properties of glass fiber and fibrous reinforcing material in terms of rigidity, strength, and impact resistance, resulting in unsatisfactory physical properties.

(Problems to be Solved by the Invention) Conventional polyamide resin compositions have low dimensional stability, as their molded products, especially molded products obtained by injection molding, undergo deformation such as warping, and cannot be shaped into desired shapes. There was a problem in that it was not possible to obtain a molded product.

Therefore, the present invention solves these problems and provides a polyamide resin composition that can obtain a molded product having a desired shape and mechanical properties without substantially causing deformation such as warpage in the molded product. The purpose is to

[Structure of the Invention] (Means and Effects for Solving the Problems) The polyamide resin composition of the present invention comprises (A) a polyamide resin or a resin mixture containing a polyamide resin, and (B) a polyamide resin that is uniformly applied to the component (A). It is characterized by consisting of dispersed layered silicate and (C) a fibrous filler.

Component (A) constituting the composition of the present invention is a polyamide resin or a resin mixture containing a polyamide resin.

Polyamide resin has acid amide bonds (-CON
H-), specifically ε-caprolactam, 6-aminocaproic acid, ω-enantholactam, 7-aminononanoic acid, 11-aminoundecanoic acid, 9
- Polymers or copolymers obtained from aminononanoic acid, α-pyrrolidone, α-piperidone, etc.; diamines such as hexamethylene diamine, nonamethylene diamine, undecamethylene diamine, dodecamethylene diamine, mexylylene diamine, and terephthalic acid; Examples include polymers or copolymers obtained by polycondensation with dicarboxylic acids such as isophthalic acid, adipic acid, and sebacic acid, or blends thereof.

The polyamide resin of component (A) has an average molecular weight of 9.00.
0 to 30,000 is preferred.

Other resins used when component (A) is a mixture of polyamide resin and other polymers include polypropylene, A
Examples include BS resin, polyphenylene oxide, polycarbonate, polyethylene terephthalate, and polybutylene terephthalate.

When component (A) is used as a mixture, it is preferable that the content of the polyamide resin is 80% by weight or more.

Component (B) is a layered silicate. This component (B) is a component that contributes to imparting excellent mechanical properties and low warpage to the molded article obtained from the polyamide resin composition.

The preferred shape is usually a thickness of 6 to 20 people and a side length of 0.002 to 1LLm.

The layered silicate is characterized in that when dispersed in component (A), each layer maintains an average interlayer distance of 20 Å or more and is uniformly dispersed. In the present invention, a layered silicate refers to a unit of material with a side of 0.002 to 1 μm and a thickness of 6 to 20 μm.

In addition, the interlayer distance refers to the distance between the centers of gravity of the flat plates of layered silicate, and the average value of the interlayer distance refers to the interlayer distance measured by measuring the interlayer distance between the nearest layer and another layer that has not yet been measured. This is the interlayer distance of the layer, and after repeatedly measuring several layers, the arithmetic mean is obtained.Furthermore, being uniformly dispersed means that each layer of layered silicate is Or, polyliths with an average overlap of 5 or less layers are arranged in parallel, randomly, or in a mixture of parallel and random layers, and 50 weights of 1% or more, preferably 70 weight% or more, form local lumps. It refers to the state of being dispersed without any

As raw materials for such layered silicates, it is preferable to use materials that have the property of swelling with water and/or organic substances.
A layered phyllosilicate mineral composed of a layer of magnesium silicate or aluminum silicate can be exemplified. Specifically, examples include smectite clay minerals such as montmorillonite, sabonite, beidellite, nontronite, hectorite, and sudibunsite, as well as vermiculite and halloysite, which may be natural or synthetic. Among these, montmorillonite is preferred, and the cation exchange capacity is 50 to 320 milliequivalents/100 g.
, and more preferably 90 to 200 milliequivalents of 7100 g.

There is no particular restriction on the method for uniformly dispersing the layered silicate of component (B) in a polyamide resin or a resin containing polyamide, but when the raw material for the layered silicate of the present invention is a multilayered clay mineral, Alternatively, it may be brought into contact with a swelling agent to spread the glabella in advance to facilitate incorporation of the monomer between the layers (and then mixed with a polyamide monomer and polymerized (see JP-A-62-74957)).

In addition, a polymer compound is used as a swelling agent, and the gap between the layers is
A method may also be used in which the particles are spread to a thickness of 0 Å or more, and then kneaded with a polyamide resin or a resin containing the same to be uniformly dispersed.

The blending ratio of component (B) is preferably 0.05 to 15 parts by weight, more preferably 0.1 to 10 parts by weight, per 100 parts by weight of component (A). (B) The blending ratio of component is 0.0
If it is less than 5 parts by weight, the effect of preventing warpage of the molded product and the improvement in rigidity and heat resistance will be reduced, which is undesirable. If it exceeds 15 parts by weight, the fluidity of the resin composition will decrease to the edge,
It is not preferred because it may not be suitable as a material for injection molding.

Component (C) is a fibrous filler. This component (C) is a component that contributes to imparting excellent mechanical properties and heat resistance to the polyamide resin molded article.

The blending ratio of component (C) is preferably 20 to 115 parts by weight, more preferably 25 to 100 parts by weight, per 100 parts by weight of component (A). If the blending ratio of component (C) is less than 20 parts by weight, the excellent mechanical properties and thermal properties provided by the fibrous filler will not be sufficient, and the impact strength will also be low, which is undesirable. Exceeding this is not preferable because the fluidity of the composition decreases, the surface of the molded product may not be finished smoothly, and a satisfactory molded product may not be obtained.

(C) Components include glass fiber and carbon fiber.

Fibrous inorganic fillers such as auralastonite, silicon nitride,
Examples include ceramic whiskers such as potassium titanate.

The shape of the fibrous filler of component (C) is not particularly limited, but for example, in the case of glass fibers and carbon fibers, it is preferable that the fiber diameter is 2 to 20 μm;
More preferably, the thickness is 4 to 15 μm. Also,
It is preferable that the aspect ratio (ratio of fiber length/11A fiber diameter) is 3 to 70 in the molded article, more preferably 5.
-50 is preferred.

If the fiber diameter is too small, it will be difficult to manufacture.
If it is too large, the mechanical properties of the molded article, especially the impact strength, will deteriorate, which is not preferable.

Further, if the aspect ratio is too small, there is no reinforcing effect, and if the aspect ratio is too large, warpage during molding becomes large, which is not preferable.

The auralastonite preferably has an aspect ratio of 3 to 70, and the silicon nitride and potassium titanate preferably have a fiber diameter of 0.1 to 3 μm.

In addition to the above-mentioned components (A) to (C), the resin composition of the present invention may also include dyes, pigments, moldability improvers,
Particulate reinforcements, plasticizers, heat resistance modifiers, foaming agents, flame retardants, etc. can be blended.

The method for producing the resin composition of the present invention is not particularly limited as long as each component can be uniformly dispersed. For example, the raw material for the silicate of component (B) is a multilayered clay mineral. In this case, the silicate mineral of component (CB) is mixed with the monomer forming component (A) by the method described in JP-A No. 62-74957, and the silicate mineral of component (CB) is polymerized, and then the monomer forming component (C) is mixed. A method of blending a fibrous filler, a method of mixing and blending component (C) into a melt-kneaded product of components (A) and (B), or a powder or pellet form consisting of components (A) and (B). A method such as blending component (C) into a molded product and then melting and kneading the mixture can be applied.

The present invention solves the disadvantages of warpage and deformation during molding, which are the disadvantages of compositions in which polyamide resin is filled with fibrous reinforcement such as glass fiber to improve mechanical strength and heat resistance, by using layered silicate. This is improved by uniformly dispersing it in the polyamide resin. The reason is not clear, but
This is thought to be because uniformly dispersing the layered silicate in the polyamide resin has some influence on the crystalline state of the polyamide resin, and has the effect of making the crystallization rate uniform during the cooling process.

(Example) Example 1 100 g of montmorillonite, in which the average thickness of one unit of layered silicate is 9.5 mm and the average length of one side is about 0.1 μm, is dispersed in 1 off of water, and 51.2 g of montmorillonite is dispersed in 1 off of water. 12-aminododecanoic acid and 24 mg of concentrated hydrochloric acid were added, stirred for 5 minutes, and then filtered. Furthermore, after thoroughly washing this, it was vacuum dried. Through this operation, a complex of ammonium 12-aminododecanoate ion and montmorillonite was prepared. The layered silicate content in the composite was 80% by weight.

Further, as measured by X-ray diffraction of this composite, the silicate glabellar distance was 18.0.

Next, 1 kg of ε-caprolactam, 1 kg of water, and 45 kg of the above-mentioned complex were placed in a reaction vessel equipped with a stirrer, and the mixture was stirred at 100° C. so that the inside of the reaction system was in a uniform state. Furthermore, the temperature was increased to 260°C, and 15kg/c
The mixture was stirred for 1 hour under a pressure of m''. Thereafter, the pressure was released, and the reaction was carried out under normal pressure for 3 hours while evaporating water from the reaction vessel.

After the reaction was completed, the reaction product taken out in the form of a strand from the lower nozzle of the reaction vessel was cooled with water and cut to obtain a pellet made of polyamide resin (average molecular weight 15.000) and montmorillonite. This pellet is immersed in hot water to extract unreacted monomer (approximately 10%),
After removal, it was dried in vacuo.

Thereafter, 43 parts by weight of glass fibers with an average fiber diameter of 10 μm were added to 100.4 parts by weight of this pellet, and the mixture was mixed using a single-screw extruder with a screw diameter of 50 mm (Ube Industries Ltd.
The resin composition of the present invention was obtained by melt-kneading the resin composition.

The obtained resin composition was injection molded under the following conditions to obtain a box-shaped test piece as shown in the figure, and the degree of warpage was measured for this test piece.

Straight bean injection molding machine: ■Japan Steel Fracture N l 40 B II
Cylinder setting temperature: C, 240°C: C2270°C:
C, 270°C: C4270°C: Nozzle heater 270
°C Injection pressure Crab - Next pressure 600kg/cm2 Mold temperature: Moving mold 80°C: Fixed mold 80°C Injection time: 13 seconds Cooling time: 20 seconds Measure the dimensions A and B in the diagram (which is a diagram for explaining the measurement method of

It was determined from the following formula using dimension B as a reference. The results are shown in the table.

Warpage (warpage of inner dowel) (%) = In addition, the obtained resin composition was injection molded under the following conditions to obtain A.
A test piece having a shape conforming to STM was obtained, and the tensile yield point strength and flexural modulus of the test piece were measured. The results are shown in the table.

Uto-shape Ezu injection molding machine: manufactured by Toshiba Machinery Co., Ltd. 15-80 cylinder - set temperature: C, 220℃: C2260℃: C, 260℃:
C4 (nozzle) 260℃ Injection pressure 650kg/cm" Injection time 114 seconds Cooling time = 30 seconds Tension Bow point Sheath and bending Tensile yield point Strength: ASTM-D-638 Flexural modulus:
ASTM-D-790 All tests were conducted at 23° C. in an absolutely dry state.

Example 2.3 and Comparative Examples 1 to 6 A resin composition was obtained in the same manner as in Example 1 using each component shown in the table (each numerical value in the table is expressed in parts by weight), and in the same manner as in Example 1. Each measurement test was conducted. The results are shown in the table.

In addition, as a result of X-ray diffraction measurement, all of the compositions in the above Examples and Comparative Examples had a distance between silicate layers of 100 Å or more.

As is clear from the table, in the comparative example, the warpage was 7%.
In contrast, in this example, it is less than 6.1%, which shows that the warpage is significantly improved.

[Effect of the Invention 1] The polyamide resin composition of the present invention significantly improves deformation such as warpage of a molded article obtained by molding, particularly injection molding, compared to conventional compositions.

[Brief explanation of the drawing]

The figure is an explanatory diagram of a method for measuring warpage.

Claims (3)

[Claims] (1) A polyamide characterized by consisting of (A) a polyamide resin or a resin mixture containing a polyamide resin, (B) a layered silicate uniformly dispersed in the component (A), and (C) a fibrous filler. Resin composition. (2) The blending ratio is (B) to 100 parts by weight of component (A).
) component 0.05-15 parts by weight and (C) component 20-1
The polyamide resin composition according to claim 1, wherein the amount is 15 parts by weight. (3) The layered silicate containing the component (B) is uniformly dispersed and has a side of 0.002 to 1 μm and a thickness of 6 to 20 Å, and each layered silicate is spaced apart by 20 Å or more on average. 2. The polyamide resin composition according to claim 1, wherein: