JPS5846218B2 - Glass fiber reinforced thermoplastic resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to glass fiber reinforced thermoplastic resin compositions.

More specifically, glass fibers are added in an amount of 5 to 60 weight φ to a resin composition consisting of a styrene copolymer containing α, β unsaturated carboxylic acid as a copolymerization component and a polyamide resin. , relates to a glass fiber-reinforced thermoplastic resin composition that has good paintability and high heat resistance.

Traditionally, glass fiber-reinforced styrenic resins have been known for their dimensional accuracy,
It has the advantages of excellent dimensional stability and rigidity, and is also inexpensive.

However, when a molded product is painted, it has the disadvantage that a good alignment cannot be obtained, and furthermore, it has poor thermal properties.

Furthermore, although glass fiber reinforced polyamide has excellent heat resistance and the appearance of molded products is good, it has major drawbacks such as significant deterioration of physical properties and dimensional changes due to moisture absorption.

Furthermore, polyamide mixed with glass fiber has a 10 to 40
% of a thermoplastic resin to improve the dimensional change due to moisture absorption of polyamide is described in Japanese Patent Publication No. 48-13944.

However, as mentioned herein, a major drawback is that the inclusion of a thermoplastic resin of 40 or more reduces the toughness.

The present inventors investigated to obtain a glass fiber-reinforced resin that has high heat resistance, good appearance after painting, and excellent adhesion of the paint film, and found that it contains α and β unsaturated carboxylic acids as a copolymer component. It has been found that a glass fiber-reinforced resin composition made of a styrene copolymer and a polyamide gives very favorable results.

That is, the present invention provides a resin composition 40 to 80% by weight of a styrene copolymer containing α,β unsaturated carboxylic acid as a copolymerization component and a polyamide of 80 to 20% by weight.
Provided is a glass fiber reinforced thermoplastic resin composition comprising 95 weight factors and 60 to 5 weight factors of glass fibers.

The styrene copolymer used in the present invention has α as a copolymer component.
, it is essential that it contains a β-unsaturated carboxylic acid.

By containing the α,β unsaturated carboxylic acid, the appearance of the molded product of the glass fiber reinforced resin composition of the present invention is improved, and a preferable appearance can be obtained when painting is performed.

Furthermore, the glass fiber reinforcement significantly improves heat resistance and mechanical properties, and even if the content of the styrene copolymer increases, the mechanical properties do not deteriorate significantly.

On the other hand, α. When using polystyrene or styrene-methyl methacrylate copolymer that does not contain β-unsaturated carboxylic acid, peeling occurs in the molded product, making it impossible to obtain a desirable appearance and also having poor heat resistance and mechanical properties. Inferior.

It is not clear what is attributable to this, but the microscopic effects of the styrene copolymer containing α,β unsaturated carboxylic acid of the present invention or the blend resin composition of general polystyrene and polyamide at a mixing ratio of 1:1 are not clear. Comparing the structures, in the case of the former, a dispersed state of particles with a diameter of 1 to 5 μm is observed in the electron micrograph, whereas in the case of the latter, particles with a diameter of ~20 μm are observed.
A dispersion state of coarse particles on the order of μ is observed.

It is thought that this difference in microstructure appears as a difference in performance of the glass fiber reinforcement.

The styrene copolymer of the present invention has styrene monomers and α, β
It can be obtained by copolymerizing an unsaturated carboxylic acid and, if necessary, adding a monomer that can be copolymerized with both.

As the styrene monomer, styrene, α-methylstyrene, P-methylstyrene, etc. can be used alone or in combination, and as the α, β unsaturated carboxylic acid, methacrylic acid,
Monomers such as acrylic acid can be copolymerized with both, such as methacrylic ester and acrylic ester.

Preferred styrene copolymers include styrene-methacrylic acid copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid-methyl methacrylate copolymer, and styrene-acrylic acid-methyl methacrylate copolymer. Such as merging.

The composition of the styrene copolymer should contain styrene monomers of 50 weight φ or more. From this point of view, the content of α, β unsaturated carboxylic acid is preferably 2 to 15% by weight, and particularly preferably the methacrylic acid content is 2 to 15% by weight in the styrene-methacrylic acid copolymer.
~9 weight φ, styrene-acrylic acid copolymer has an acrylic acid content of 2 to 12 weight multiquantum rene-methacrylic acid-methyl methacrylate copolymer and styrene-acrylic acid-methyl methacrylate copolymer In the coalescence, the methacrylic acid or acrylic acid content is 2 to 15% by weight, and the methyl methacrylate content is 2 to 30% by weight.

If the content of α,β-unsaturated carboxylic acid is too low, it is unfavorable in terms of the appearance of the molded product, heat resistance, and mechanical strength, and if the content is too high, it is unfavorable in terms of moldability.

Furthermore, by introducing methyl methacrylate into the styrene copolymer, favorable effects can be obtained on the moldability of the obtained glass fiber reinforced resin composition and the appearance of molded products, but the inclusion of methyl methacrylate If the amount is too large, the desirable properties of polystyrene will be lost and the cost will increase, which is not preferable.

Suitable polyamides for use in the present invention include polycaprolactam (nylon-6), polyhexamethylene adipamide (nylon-6,6), polyhexamethylene adipamide (nylon-6, IO), and the like.

Also, the mixing ratio of styrene copolymer and polyamide,
Styrene copolymer 2-15% by weight and polyamide 80-2%
0 weight is preferred.

If the amount of styrene copolymer is too large, it is unfavorable in terms of the appearance and mechanical properties of the molded product after painting, and if the amount of polyamide is too large, it is unfavorable in terms of paint adhesion.

The length of the glass fiber used in the present invention is desirably as long as possible, as long as it is longer than the critical length at which the reinforcing effect appears.
0.4 considering workability during mixing, cutting during molding process, etc.
It is particularly preferable that the length of the glass fiber in the final molded product be about 0.2 to 2.0 mm.

It is not necessary to perform any particular surface treatment on the glass fibers, and commercially available products that have been subjected to various treatments can be used as they are.

Further, if the content of glass fiber exceeds 5 to 60% by weight based on the glass fiber reinforced resin composition, the molding processability decreases, and if it is less than 5% by weight, a sufficient reinforcing effect cannot be obtained.

The glass fiber reinforced resin composition of the present invention has high heat resistance,
It is a material suitable for painting, has significantly improved mechanical properties due to glass fiber reinforcement, and has good moldability, so it can be widely used as large molded products in automobile parts, home appliance parts, etc.

In carrying out the present invention, for example, pelletized polyamide, styrene copolymer, and glass fiber may be mixed in a blender and melt-mixed through an extruder, or only two polymers may be mixed in a blender first and then extruded. The mixture is melt-mixed through a machine, and the pelletized mixture is mixed with glass fibers and melt-mixed using an extruder.

Alternatively, a mixture of pelletized polyamide, styrene copolymer, and glass fiber may be directly put into the hopper of an injection molding machine to obtain a molded product at the same time as melt-mixing.

The composition of the present invention may be used with additives such as heat or light stabilizers, dyes and pigments, flame retardants, and plasticizers added thereto, if necessary.

Next, examples will be shown to explain the present invention in more detail.

Parts indicate parts by weight. Examples 1 to 3, Comparative Example 1 Well-dried nylon-6 (Amiran CM101 manufactured by Toshi)
7) Pellets and styrene-methacrylic acid copolymer (methacrylic acid content: 6.5 parts by weight) pellets [Example]
Alternatively, polystyrene (Styron 683 manufactured by Asahi Dow) pellets [Comparative Example 1] were mixed in the proportions shown in Table 1 and passed through a twin-screw extruder to obtain a pellet-shaped polymer mixture.

The pellets of the polymer mixture obtained here and the glass fibers were
The glass fiber content shown in the table was mixed at a ratio that would result in a glass fiber content of 250 to 27
A glass fiber reinforced resin composition in the form of pellets was obtained at 0°C.

A test molded article was molded from this composition using an injection molding machine.

Tensile strength,
Izot impact strength, heating deformation temperature, bending strength and bending elastic modulus were measured by the method described in ASTM test method D790.

Regarding paintability, after painting the molded product with acrylic paint, its appearance was judged with the naked eye, and the adhesion test of the paint film was conducted after a 72-hour moisture resistance test at 50°C and 98% RH or higher. This was carried out on molded products.

The obtained results are shown in Table 1 together with glass fiber reinforced polystyrene and glass fiber reinforced nylon ~6.

The glass fiber reinforced resin composition of the present invention has high heat resistance,
It can be seen that the paintability is good and the mechanical properties are also excellent.

Examples 4 and 5 Well-dried nylon-6 (Amiran CM101 manufactured by Toshi)
7) 50 parts of pellets and 50 parts of styrene-methacrylic acid copolymer (methacrylic acid content: 6.5 parts by weight) pellets
The components were mixed and passed through a twin-screw extruder to obtain a pelletized polymer mixture.

The pellets of the polymer mixture obtained here and the glass fibers were
The glass fiber content shown in the table was mixed at a ratio that would result in a glass fiber content of 250 to 27
A glass fiber reinforced resin composition in the form of pellets was obtained at 0°C.

Physical property tests were conducted in the same manner as in Example 1.

The results are shown in Table 2. As the glass fiber content increases, the physical properties significantly improve.

Example 6 A glass fiber reinforced resin composition was prepared in the same manner using a styrene-acrylic acid copolymer (acrylic acid content: 8.0 parts by weight) in place of the styrene-acrylic acid copolymer in Example 2. It was manufactured and physical property tests were conducted.

The results are shown in Table 2. Example 7 Instead of the styrene-methacrylic acid copolymer in Example 2, styrene-methacrylic acid-methyl methacrylate copolymer (methacrylic acid content: 5 parts by weight, methyl methacrylate content: 15 parts by weight) A similar test was conducted using

The results are shown in Table 2.

Example 8 Nylon-6 was used instead of nylon-6 in Example 2.
, 6 (manufactured by Asahi Kasei Ona 13008) was used to conduct a similar test.

The results are shown in Table 2. Furthermore, the paintability of the injection-molded glass fiber reinforced resin compositions obtained in Examples 4 to 8 was tested in the same manner as in Example 1, and the results showed that all the coated products had excellent appearance and adhesion of the coating film. We obtained the following results.

The composition of Example 2 of the present invention was also measured for hygroscopicity, dimensional change due to moisture absorption, molding shrinkage rate, and warpage of the molded product.

Hygroscopicity and dimensional changes due to moisture absorption were determined by measuring the weight increase and dimensional change after immersing the test piece in 60°C hot water for 72 hours.

The molding shrinkage rate and warpage of the molded product were measured using an injection molded flat plate.

The results are shown in Tables 3 and 4 in comparison with glass fiber reinforced nylon-6 (Comparative Example 3) and glass fiber reinforced polystyrene (Comparative Example 2).

Claims (1)

[Scope of Claims] 1 Copolymer consisting of a styrene compound and an α,β unsaturated carboxylic acid, or a copolymer consisting of a styrene compound, an α,β unsaturated carboxylic acid, and an α,β unsaturated carboxylic acid ester 20 -80% by weight (based on resin components) and a polyamide resin of 80 to 20% by weight (based on resin components), and 5 to 60% by weight φ (based on weight class composition) of glass fibers are added to the resin composition. Characteristic glass fiber reinforced thermoplastic resin composition. 2. A patent claim characterized in that the copolymer consisting of a styrene compound and an α,β unsaturated carboxylic acid is a styrene-methacrylic acid copolymer consisting of 91 to 98 weight φ of styrene and 9 to 2 weight of methacrylic acid. The resin composition according to item 1. 3 A copolymer consisting of a styrene compound and α, β unsaturated carboxylic acid contains 88 to 98% by weight of styrene and 1 part of acrylic acid.
2. The resin composition according to claim 1, which is a styrene-acrylic acid copolymer having a weight φ of 2 to 2. 4 A copolymer consisting of a styrene compound, α, β unsaturated carboxylic acid, and α, β unsaturated carboxylic acid ester is styrene 55 to 96 weight φ, methacrylic acid or acrylic acid 2 to 15 weight φ, and methyl methacrylate. 2-30
The resin composition according to claim 1, which is a styrene-methacrylic acid-methyl methacrylate copolymer or a styrene-acrylic acid-methyl methacrylate copolymer having a weight φ.