JP2000043066A - Production of fiber reinforced thermoplastic resin molded object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a fiber reinforced thermoplastic resin molded object containing fibrils of a polymeric liquid crystal in a predetermined direction, not lowering mechanical strength in a desired area and excellent in moldability. SOLUTION: A molding material based on a resin compsn. wherein a liquid crystal resin (A) of a fibril state is dispersed in a thermoplastic resin (B) having melting temp. lower than the transition point of the liquid crystal resin (A) is once formed into a resin sheet shape and this resin sheetlike article is formed into a desired shape by pressure molding to produce a fiber reinforced thermoplastic resin molded object. In this production method, a pressure molding condition is set to a temp. range from the melting temp. of the thermoplastic resin (B) to the transition point of the liquid crystal resin (A) and pressure molding is performed so that the surface within a range of 0-30 deg. in the pressing direction to the resin sheetlike article becomes 50% or more of the total pressing area.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a fiber-reinforced thermoplastic resin molded article.

[0002]

2. Description of the Related Art Conventionally, fiber-reinforced thermoplastic resin molded articles have been used together with so-called "engineering plastics".
Due to its excellent heat resistance and dimensional stability, it is used for automobile parts, for example, door pads, inside panels, bumper beams and the like. Above all, a thermoplastic polyester liquid crystal polymer is a preferable material for the above-mentioned automotive parts because of its excellent heat resistance, flame retardancy, high rigidity, chemical resistance, dimensional stability, and moldability.

[0003] On the other hand, in order to impart the above excellent properties to other resins, mixing with other thermoplastic resins is also performed. At this time, it is melted and kneaded with other thermoplastic resin and extruded to form a fine fibrous substance (hereinafter "fibril").
), And a resin composition having various characteristics not found in other thermoplastic resins can be obtained.

[0004] However, a composition containing a large amount of this expensive liquid crystal polymer has an economic disadvantage.

[0005] Therefore, as long as it can be mixed with the thermoplastic resin, the fibrils which are as thin as possible and have a high aspect ratio and the thermoplastic resin which can be melt-kneaded below the melting point of the fibrils are contained at specific weight fractions. A composite material has been proposed (Japanese Unexamined Patent Publication No. Hei 7-188569).

Further, a resin composition comprising a liquid crystalline polyesteramide which forms an anisotropic molten phase and a small amount of a polyolefin having a specific molecular weight is injection-molded under specific conditions to obtain a resin molded product having a small decrease in strength at a weld portion. It is also known to obtain (Japanese Patent Application Laid-Open No. 7-233310).

[0007]

[0007] However, the above-mentioned publication 7
The composite material disclosed in Japanese Patent No. 188569 has a problem that fibrils are randomly oriented in the obtained molded article, and characteristics such as a high elastic modulus and a low shrinkage characteristic of fibrils composed of a liquid crystal polymer cannot be sufficiently exhibited. there were.

Further, the molded article described in the above-mentioned Japanese Patent Application Laid-Open No. 7-233310 cannot exhibit the flexibility and the different moldability peculiar to the polyolefin because the amount of the liquid crystalline polyesteramide is larger than the amount of the polyolefin. .

[0009] The present invention solves the above-mentioned problems, and a fibril of a polymer liquid crystal is oriented in a predetermined direction. An object of the present invention is to provide a method for producing a plastic resin molded article.

[0010]

The fiber-reinforced thermoplastic resin molded article of the present invention comprises a fibril-state liquid crystal resin (A) comprising:
A molding material containing a resin composition as a main component dispersed in a thermoplastic resin (B) having a melting temperature lower than the transition point of the liquid crystal resin is once formed into a resin sheet, and then the resin sheet is formed. Is a method for producing a fiber-reinforced thermoplastic resin molded article by press-molding into a desired shape, wherein the press-molding conditions are not lower than the melting temperature of the thermoplastic resin (B) and not higher than the transition point of the liquid crystal resin (A). The pressing is performed so that the surface at which the pressing direction with respect to the resin sheet is in the range of 0 to 30 ° is 50% or more of the total pressing area.

The liquid crystal resin (A) used in the present invention
As long as the liquid crystal transition temperature is higher than the melting temperature of the thermoplastic resin, it is not particularly limited, but a wholly aromatic polyester, a semi-aromatic polyester, a thermoplastic liquid crystal polyester amide, or the like is easily used. It is preferable because it can be fibrillated. Examples of the wholly aromatic polyester include Polyplastic Corporation, trade name "Vectra"; Sumitomo Chemical Co., Ltd., trade name "Suika Super"; Nippon Petrochemical Co., Ltd., trade name "Zyder", and the like. At least one can be used.

The semi-aromatic polyester includes, for example, "Rodrun" (trade name, manufactured by Unitika); "Novaculate" (trade name, manufactured by Eastman Kodak Co.), and at least one of these can be used.

If the average aspect ratio of the fibrils of the liquid crystal resin (A) in the fibril state in the present invention is too large, a large pressure is required at the time of press molding, and if too small, the average aspect ratio of the fibrils to the thermoplastic resin (B) due to the fibrils (A). Is preferably 50 to 5,000, and more preferably 100 to 3,000.

The thermoplastic resin (B) used in the present invention is not particularly limited as long as it has a melting temperature lower than the liquid crystal transition temperature of the thermoplastic resin (A). Polyethylene such as high density polyethylene, low density polyethylene, linear low density polyethylene; polypropylene such as homopolypropylene, block copolymerized polypropylene and random copolymerized polypropylene; polybutylene; ethylene-vinyl acetate copolymer; polyvinyl acetate; polystyrene; Examples thereof include vinyl chloride; polyethylene terephthalate; and polytetrafluoroethylene, and at least one of them can be used.

The thermoplastic resin (B) has a melt index (according to JIS K7210) that is too large,
Even if it is too small, the moldability is reduced.
To 20 g / 10 min, and more preferably 0.1 to
10 g / 10 min.

The above melting temperature and transition temperature are in accordance with JIS K7
The peak temperature at the time of temperature rise measured by differential thermal analysis (DTA) or differential thermal scanning calorimetry (DSC) measured in accordance with Standard No. 121, which indicates a melting peak temperature. The temperature indicates a melting point, and in the case of an amorphous resin, indicates a peak temperature closest to a temperature at which molding is possible under normal pressure.

The fibrils (A) and (B) in the present invention
When the fibril (A) is too small, the reinforcing effect of the fibril (A) is not observed, and when the fibril (A) is too large, the strength of the obtained molded body is reduced.
It is limited to 01 to 1, preferably 0.01 to 0.7, and more preferably 0.03 to 0.3.

In order to make the liquid crystal resin into a fibril state, the liquid crystal resin and the thermoplastic resin (B) are mixed, melt-kneaded at a temperature not lower than the transition point of the liquid crystal resin, and extruded while giving elongational flow. . The method of extrusion is not particularly limited, and examples thereof include a method using a twin-screw extruder and a kneader.

In the above-mentioned method, when extruding while giving an elongational flow, the elongation speed is too slow or too fast to form a fibril state.
ec is preferable, and more preferably 0.3 to 100 / s
ec.

The molding material of the present invention contains a resin composition comprising the above fibril (A) and thermoplastic resin (B) as a main component. The resin composition, if necessary, as long as the effects of the present invention are not impaired, a flame retardant, a filler, an antioxidant,
One or more of various additives such as a nucleating material and a pigment may be added.

In the present invention, the above molding material is formed into a sheet. The method of forming into a sheet is not particularly limited. For example, a method of press-forming the extruded molding material under heating, after extruding from a T-die, passing between two cooling rolls having a predetermined clearance. Sizing method.

In the present invention, the resin sheet obtained as described above is pressed at a temperature not lower than the melting temperature of the thermoplastic resin and not higher than the transition point of the liquid crystal resin. If the temperature of the press molding is lower than the melting temperature of the thermoplastic resin, shaping cannot be performed, and if the temperature is higher than the transition point of the liquid crystal resin, the liquid crystal resin once in a fibril state relaxes and becomes particulate, reinforcing effect and dimensional stability The reason for this is that a molded article having low properties is obtained.

In the present invention, the surface where the pressing direction with respect to the resin sheet is in the range of 0 to 30 ° is set to be 50% or more of the total pressing area. This is because, by setting the pressing direction of the resin sheet to 0 ° to 30 °, the fibrils dispersed in the resin sheet in this range are oriented toward the elongation direction of the molding material.

[0024]

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIGS. 1A and 1B show a pressing mold used in the present invention, wherein FIG. 1A is a top view and FIG. 1B is a sectional view taken along line AA in FIG. In FIG. 1, reference numeral 1 denotes a lower mold for press molding, and a wall 14 is provided from the parting line P toward the bottom 12 at an angle of θ with respect to the pressing direction [X in FIG. 1B]. ing. A height h ₁ from the parting line P to the bottom 12 is provided, and a recess 16 is provided at a height of h ₂ from the bottom 12.

[0026] Figure 2 is a cross-sectional view of the upper mold 2 forming the cavity corresponding to the shape of the molded body molded should when it is the lower mold 1 and closed, the intersection of the wall portion 24 from the bottom chamfer R ₁ Processing has been done. This intersection is also chamfered on the lower die with the same diameter. In addition, the inclined portion 28 up to the ridge portion 26 (corresponding to the concave portion 16 of the lower mold) is chamfered with R _{2 at} the intersection with the bottom portion 22 and with R _{3 at} the intersection with the inclined portion 28 and the ridge portion 26. Has been made to form a symmetrical type. In addition, the chamfering process is performed so as to correspond to the lower die 1 and the upper die 2.

FIG. 3 shows that a liquid crystal resin (A) in a fibril state is placed in a cavity (not shown) formed when the lower mold 1 and the upper mold 2 are closed from the transition point of the liquid crystal resin. Molded product 3 obtained by injecting a resin composition dispersed in a thermoplastic resin (B) having a low melting temperature
FIG. 3 is a schematic diagram showing the shape of the fibrils in the orientation state of FIG. In the portion 32 corresponding to the bottom 12 of the lower mold 1 and the bottom 22 of the upper mold 2, almost no orientation is observed, and in the wall 34 corresponding to the wall 14 of the lower mold 1 and the wall 24 of the upper mold 2. Fibril orientation is observed in the resin flow direction.

[0028]

EXAMPLES Next, the details of the present invention will be described in more detail with reference to examples.

Example 1 A liquid crystal resin having the composition shown in Table 1 (manufactured by Polyplastics, trade name "Vectra", product number "A950", liquid crystal transition temperature 280 ° C.), and a high-density polyethylene Product number "H" manufactured by Mitsubishi Chemical Corporation
Y540, melt index 1 g / 10 min, density 0.
961 g / cm ³ and a melting temperature of 135 ° C.) are kneaded with a twin-screw extruder (model “PCM-30”, manufactured by Ikegai Iron Works Co., Ltd.) set at 290 ° C. for both the barrel and the mold. The resin sheet was extruded from a T-die and passed between opposed metal rolls having a clearance of 3.0 mm and adjusted to a temperature of 20 ° C. to obtain a 2.8 mm thick resin sheet.

The obtained resin sheet is heated to 170 ° C.
The lower mold shown in FIG. 1 and the upper mold (r₁= 25m
m, r_Two= 50mm, r_Three= 80mm, r_Four= 140m
m, h ₁= 150mm, h_Two= 50 mm, θ = 24 °,
R₁= 7mm, R_Two= 7mm, R_Three= 7mm, mold temperature
50 ° C.) and 1 kg / cm^TwoPress with pressure
It is pressed and molded between the upper mold shown in FIG.
I got At this time, the cross-sectional area of the wall and the entire development surface of the molded body
The rate of closing the product was 68%.

(Example 2) h ₁ = 30 for the lower mold 1 and the upper mold 2
A molded product 3 was obtained in the same manner as in Example 1 except that 0 mm and θ were set to 12 °. At this time, the ratio of closing to the cross-sectional area of the wall and the entire development area of the molded body was 80%.

Example 3 A molded product 3 was obtained in the same manner as in Example 1 except that the liquid crystal resin and the high-density polyethylene had the compositions shown in Table 1.

Comparative Example Same as Example 1 except that a rectangular parallelepiped cavity was provided between the upper mold and the lower mold to obtain a 2.0 mm thick molded body having a rectangular cross section (see FIG. 4). It is. At this time, the ratio of closing to the cross-sectional area of the wall and the entire development area of the molded body was 0%.

Evaluation of molded article Tensile strength A No. 2 tensile test piece was prepared from the wall portion 34 of the obtained molded body according to JIS K7113, and the tensile strength was measured. 2. Linear expansion coefficient 200 × 10 × 2.0 m from the wall 34 of the obtained molded body
m, and the length L ₀ of the test piece at 80 ° C.
And the length L ₁ of the test piece at 0 ° C. were measured (L ₁ −
L ₀ ) / L ₀ / (80−0) was obtained and defined as a coefficient of linear expansion.

The above results are summarized in Table 1.

[0036]

[Table 1]

[0037]

According to the method for producing a fiber-reinforced thermoplastic resin molded article of the present invention, the fibril-state liquid crystal resin (A) is used in a thermoplastic resin (B) having a melting temperature lower than the transition point of the liquid crystal resin. A method for producing a fiber-reinforced thermoplastic resin molded article in which a molding material containing a resin composition dispersed as a main component is once formed into a resin sheet, and then the resin sheet is pressed into a desired shape. Wherein the pressing conditions are:
A surface having a temperature equal to or higher than the melting temperature of the thermoplastic resin (B) and equal to or lower than the transition point of the liquid crystal resin (A) and having a pressing direction of 0 to 30 ° with respect to the resin sheet is 5% of the total pressing area.
Since the pressure molding is performed so as to be 0% or more, a molded body having excellent mechanical strength such as tensile strength and a small coefficient of linear expansion can be obtained.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a lower mold for a press-forming mold used in the present invention, (a) is a top view thereof, and (b) is an A-
It is A sectional drawing.

FIG. 2 is a cross-sectional view showing an upper die of a press-molding die used in the present invention.

FIG. 3 is a schematic view of a molded article obtained according to the present invention.

FIG. 4 is a schematic view of a molded article obtained in Comparative Example 1.

[Explanation of symbols]

 Reference Signs List 1 pressing die (lower die) 2 pressing die (upper die) 3, 4 molded body 12, 22, 32 bottom 14, 24, 34 wall

Claims (1)

[Claims] 1. A molding material containing a resin composition in which a liquid crystal resin (A) in a fibril state is dispersed in a thermoplastic resin (B) having a melting temperature lower than the transition point of the liquid crystal resin as a main component. A method for producing a fiber-reinforced thermoplastic resin molded article in which a resin sheet is once formed into a desired shape, and then the resin sheet is press-molded into a desired shape. ), The surface having a temperature in the range of the transition point of the liquid crystal resin (A) and the pressing direction of the resin sheet in the range of 0 to 30 ° is 50% or more of the total pressed area. A method for producing a fiber-reinforced thermoplastic resin molded article, comprising: