JPH07148875A - Plate-like laminated thermoplastic resin molded body - Google Patents

Abstract

PURPOSE:To prevent warp of a laminated molded body and improve dimensional precision by making a plate-like laminated thermoplastic resin molded body of two kinds of thermoplastic resins having different flexural moduli and setting a sectional area occupied by the resins in a cross section cut by a plane parallel in the direction of plate thickness to a value within a specified range. CONSTITUTION:A plate-like molded body is formed by layering two kinds of thermoplastic resins having a flexural modulus of 0.5 or less. A boundary of the two kinds of the thermoplastic resins in a cross section cut by a plane parallel in the direction of plate thickness forms an irregularity, and satisfies expressions I and II simultaneously in the cross section. In the expressions, A represents a sectional area occupied by a thermoplastic resin having high flexural modulus, B represents a sectional area occupied by a thermoplastic resin having low flexural modulus, C represents a total sectional area of a plate-like laminated thermoplastic resin molded body, and I represents a second moment at area at the thermoplastic resin having high flexural modulus relating to an axis which passes the center of figure of the thermoplastic resin having high flexural modulus and is vertical to the direction of plate thickness being in the cross section.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate-shaped laminated thermoplastic resin molding having less warpage.

[0002]

2. Description of the Related Art Thermoplastic resins are processed into various molded articles and used in a wide range of fields. A plate-shaped thermoplastic molded body is generally manufactured by injection molding. For example, a plate-shaped thermoplastic resin molded body having different material properties on the front surface and the back surface is first positioned on one side. It is manufactured by molding a thermoplastic resin and then molding the other thermoplastic resin.

[0003]

However, in this method, the thermoplastic resin on one side previously molded has already been molded and solidified so that it has already shrunk to some extent, and the thermoplastic resin on the other side to be molded later does not Since the thermoplastic resin previously molded shrinks to some extent, it is molded, so that there is a large difference in the shrinkage rate between the two. Therefore, when the shape of the thermoplastic resin molded body is a plate-shaped body, the molded body has a large defect that a large warp occurs after a certain period of time and the dimensional accuracy with time is extremely deteriorated. Therefore, it has been a major problem to prevent warpage of the plate-shaped laminated thermoplastic resin molded article and obtain a molded article with good dimensional accuracy.

[0004]

Means for Solving the Problems As a result of earnest research in view of the above-mentioned problems, the present inventor has used thermoplastic resins having different flexural moduli as the thermoplastic resin constituting the laminated thermoplastic resin sheet and The inventors have found that the above problems can be solved by setting the cross-sectional area of each resin in a cross section cut along a plane parallel to the thickness direction to a value within a specific range, and have proposed the present invention.

That is, the present invention is a plate-shaped molded product in which two kinds of thermoplastic resins having different bending elastic moduli and having a bending elastic modulus ratio of 0.5 or less are laminated, and in which the plate thickness direction is 2 in at least one section cut in a plane parallel to
The boundary of the thermoplastic resin of the kind forms irregularities, and in the cross section, the following formulas (1) and (2) are simultaneously satisfied, and the plate-shaped laminated thermoplastic resin molded product is characterized.

0.2 <B / A ≦ 1.6 (1) 0.5 ≦ (C × I) / (A × I ′) <1 (2) (In the above formula, , A: A cross-sectional area occupied by a thermoplastic resin having a high flexural modulus.

B: A sectional area occupied by a thermoplastic resin having a low flexural modulus.

C: Total cross-sectional area of the plate-shaped laminated thermoplastic resin molding.

I: Second moment of area of the thermoplastic resin having a high flexural modulus with respect to an axis passing through the centroid of the thermoplastic resin having a high flexural modulus and perpendicular to the plate thickness direction and existing in the cross section.

I ': Second moment of area of the laminated thermoplastic resin sheet with respect to an axis passing through the center of the laminated thermoplastic resin sheet and perpendicular to the thickness direction and existing in the cross section. ) The thermoplastic resins constituting the plate-shaped laminated thermoplastic resin molded article of the present invention have different bending elastic moduli, and the ratio of the bending elastic moduli of these thermoplastic resins is 0.5 or less. . That is, one surface of the plate-shaped laminated thermoplastic resin molding is a thermoplastic resin having a high flexural modulus (hereinafter also referred to as a high-rigidity thermoplastic resin), and the other surface is a thermoplastic resin having a low flexural modulus. It is a resin (hereinafter, also referred to as a low-rigidity thermoplastic resin). The ratio of the flexural modulus of each of the low-rigidity thermoplastic resin and the high-rigidity thermoplastic resin (low-rigidity thermoplastic resin / high-rigidity thermoplastic resin) must be 0.5 or less, and 0.3 or less. Preferably there is. When the flexural modulus ratio exceeds 0.5, the residual stress due to the difference in shrinkage between the high-rigidity thermoplastic resin and the low-rigidity thermoplastic resin cannot be relieved by the low-rigidity thermoplastic resin, and the molded article is You cannot prevent sledging.

In the present invention, the thermoplastic resins to be laminated are preferably resins of the same kind, such as polyolefins and polyamides, in order to improve the adhesiveness between them. Further, as the high-rigidity thermoplastic resin, the bending elastic modulus is 10,000 to 100,000 kg /
Since the warp of the molded body tends to be particularly large when the one having a range of cm ² is used, the effect of the present invention becomes remarkable when such a thermoplastic resin is used. Also,
When the above-mentioned high-rigidity thermoplastic resin is used, as the low-rigidity thermoplastic resin that reduces warpage, the flexural modulus of 40
It is preferable to use one having a range of 0 to 15,000 kg / cm ² .

The thermoplastic resin used in the present invention is not particularly limited, and known thermoplastic resins can be used. For example, polyolefins such as polyethylene, polypropylene and polybutene; polystyrene, AS resin (acrylonitrile-styrene copolymer), ABS resin (acrylonitrile-butadiene-styrene copolymer).
Styrenic polymers such as: nylon 6, nylon 66
And the like; halogen-containing polymers such as polyvinyl chloride and polyvinylidene chloride.
These thermoplastic resins can be used alone or as a mixture. In the present invention, a crystalline resin such as polyamide or polyolefin is particularly preferable,
In particular, the use of polypropylene is suitable because it has a great effect of reducing warpage.

The plate-shaped laminated thermoplastic resin molding of the present invention comprises
In at least one cross section cut along a plane parallel to the plate thickness direction, the boundary between the high-rigidity thermoplastic resin and the low-rigidity thermoplastic resin described above forms unevenness. The cross section of the plate-shaped laminated thermoplastic resin molded product of the present invention taken along a plane parallel to the plate thickness direction has a number of cross sections corresponding to the number of the planes. In the present invention, if at least one of the cross-sections satisfies the requirements described below, the other cross-sections do not necessarily have to satisfy the requirements.

The shape of the boundary irregularities in the above-mentioned cross section is not particularly limited, and may be a combination of straight lines or a combination of curved lines, and may be left-right symmetrical or non-symmetrical. Specifically, FIGS.
Examples of the uneven shape include a comb shape, a wavy shape, and a combination thereof as shown in FIG. When the boundary in the cross section is not uneven and is straight as shown in FIG. 10, the residual stress due to the difference in shrinkage between the high-rigidity thermoplastic resin and the low-rigidity thermoplastic resin cannot be alleviated by the low-rigidity thermoplastic resin, It is not possible to prevent warping of the molded body.

Further, in the present invention, it is required that the following expressions (1) and (2) are simultaneously satisfied in the cross section.

0.2 <B / A ≦ 1.6 (1) 0.5 ≦ (C × I) / (A × I ′) <1 (2) (In the above formula, , A: A cross-sectional area occupied by a thermoplastic resin having a high flexural modulus.

B: Cross-sectional area occupied by a thermoplastic resin having a low flexural modulus.

C: Total cross-sectional area of the plate-shaped laminated thermoplastic resin molding.

I: Second moment of area of the thermoplastic resin having a high flexural modulus with respect to an axis passing through the centroid of the thermoplastic resin having a high flexural modulus and perpendicular to the plate thickness direction and existing in the cross section.

I ': second moment of area of the laminated thermoplastic resin sheet with respect to an axis passing through the centroid of the laminated thermoplastic resin sheet and perpendicular to the plate thickness direction and present in the cross section. ) The centroid in the above formula represents the center of gravity in the cross-sectional shape, and the second moment of area is defined in the mechanical engineering handbook (May 15, 1988, published by the Japan Society of Mechanical Engineers), A4, page 24. Which is one of the indicators of flexural rigidity.
Is one. In the present invention, the second moment of area is the commercially available software, for example, "I-DE" manufactured by SDRC.
AS VI. It can be easily calculated using "i". Further, a relatively simple shape can be calculated using the calculation formulas for various sectional shapes listed in Table 6 on pages 25 to 26 of the above-mentioned Mechanical Engineering Handbook A4.

In the above equation, the equation (1) represents the cross-sectional area ratio of the low-rigidity thermoplastic resin to the high-rigidity thermoplastic resin.
When this value becomes small, the high-rigidity thermoplastic resin suppresses the shrinkage of the low-rigidity thermoplastic resin that is molded later, and thus the effect of suppressing warpage of the plate-shaped laminated thermoplastic resin molded body is large. The equation (2) is obtained by dividing the second moment of area per unit cross-sectional area of the high-rigidity thermoplastic resin by the second moment of area per unit cross-sectional area of the plate-shaped laminated thermoplastic resin molded body. That is, when the value calculated by the equation (2) becomes large, the flexural rigidity strength per unit cross-sectional area increases, and the effect of suppressing warpage of the plate-shaped laminated thermoplastic resin molded article is great.

In the present invention, as shown by the above formula (1), B / A must be more than 0.2 and 1.6 or less, preferably 1 or less. When B / A exceeds 1.6, the effect of the high-rigidity thermoplastic resin to suppress the residual stress due to the difference in shrinkage between the high-rigidity thermoplastic resin and the low-rigidity thermoplastic resin decreases, so that the plate-shaped lamination heat It is not possible to prevent warping of the plastic resin molding. B / A is 0.2
In the following cases, warpage hardly occurs, so it is not necessary to follow the present invention.

Further, in the present invention, the above formula (2)
(C × I) / (A × I ′) must be 0.5 or more and less than 1, and as close as possible to 1 is preferable, but the effect of the present invention is 0.7 or more. It is remarkable.
Further, when the value of the above formula (2) is less than 0.5, the high-rigidity thermoplastic resin and the low-rigidity thermoplastic resin cannot sufficiently obtain the effect of suppressing the warpage of each other, and thus the laminated molded article You cannot prevent sledging. Further, if the value of the above formula (2) is 1 or more, it is not preferable because it is difficult to shape the laminated molded body in terms of shape. Further, when the above equation (2) has the same value, it is preferable that the boundary line in the cross section is long.

The thermoplastic resin used in the present invention includes conventionally known additives such as heat stabilizers, weathering agents, colorants, antistatic agents, lubricants, nucleating agents, antiblooming agents; talc,
Calcium carbonate, mica, barium sulfate, glass fiber,
Inorganic fillers such as glass beads, glass balloons, carbon fibers; organic fillers such as wood flour, chaff, powder, pulp; polybromodiphenyl ethers such as decabromodiphenyl ether, TBA derivatives, TBS derivatives, bromine-containing isocyanuric acid derivatives, etc. Brominated organic flame retardants; various phosphoric acid flame retardants; inorganic flame retardants such as antimony trioxide, magnesium hydroxide, aluminum hydroxide and red phosphorus.

The plate shape in the plate-shaped laminated thermoplastic resin molded article of the present invention means that the length in the thickness direction is relatively shorter than the length and width, and the direction parallel to the plate thickness direction. The shape viewed from is not limited to square, rectangular, polygonal such as triangle, quadrangle, pentagon, etc., circle, hollow circle (donut type), semicircle, hollow semicircle, arc shape, hollow circle. It may be arcuate, horseshoe-shaped, crescent-shaped and the like. Also, the shape of the cross section in the plate thickness direction is an arbitrary shape, for example, in addition to a rectangle,
Triangle, quadrangle, polygon such as pentagon, oblong, bow,
It may be a crescent moon type or the like. Further, the surface may be subjected to a special concave-convex processing, as long as it retains the shape of a plate-like body.

The method for producing the plate-shaped laminated thermoplastic resin molding of the present invention is not particularly limited, and known injection molding, press molding, extrusion molding, stampable molding and the like can be adopted. In particular, in the case of the core back method or the two-color molding method in the injection molding, after filling the one side of the mold with the high-rigidity thermoplastic resin, the mold core is retracted or the mold is inverted, A method of filling the other side with a low-rigidity thermoplastic resin can be adopted.

Further, there is also adopted a method in which a high-rigidity thermoplastic resin is preliminarily molded in one mold, the molded product is taken out, and then the other mold is attached and the low-rigidity thermoplastic resin is filled. it can. When this method is adopted, there is a large difference between the effects according to the present invention and the effects according to the present invention, and the effects of the present invention are great.

[0028]

The plate-shaped laminated thermoplastic resin molded product of the present invention is a molded product which is not deformed by warping and has good dimensional stability. The reason why such an effect is obtained is that the ratio of the bending elastic moduli of the high-rigidity thermoplastic resin and the low-rigidity thermoplastic resin forming the plate-shaped laminated thermoplastic resin molded article is a specific value, and
Since the boundaries of these thermoplastic resins in the cross section are uneven and further satisfy the specific formula in the cross section, the high rigidity thermoplastic resin molded previously has a low rigidity formed later. It is presumed that this is because the deformation of the thermoplastic resin molded body due to shrinkage is suppressed.

Therefore, the plate-shaped laminated thermoplastic resin molded product of the present invention is useful as various members required to have dimensional stability. For example, automobile parts such as bumpers, instrument panels, door trims; housings for word processors, personal computers, keyboards, copiers, and other office automation equipment; residential building materials such as door panels, sashes, and wall boards; toilet seats,
It can be preferably used for sanitary parts such as toilet lids.

[0030]

EXAMPLES In order to describe the present invention more specifically, examples and comparative examples will be described below, but the present invention is not limited to these examples.

The thermoplastic resins shown in Examples and Comparative Examples and those other than those already described with the symbols in the table are as follows.

Thermoplastic resin: symbol material flexural modulus (kg / cm ² ) a: propylene homopolymer 20,000 b: ethylene propylene block copolymer 15,000 c: ethylene propylene random copolymer 10,000 d: ethylene propylene block copolymer Polymer 5,000 E: Ethylene propylene block copolymer 3,000 Symbols in the table: L: Boundary length in cross section.

L ': (a) boundary line length of the test piece in FIG.

Examples and Comparative Examples Molding of the plate-shaped laminated thermoplastic resin molding and measurement of warpage were performed as follows. A molded body was obtained based on the following molding method and warpage was measured. The results are shown in Table 1. In addition, the second moment of area is "I-DEAS V" manufactured by SDRC.
I. i ”was used for the calculation.

(A) Molding method An injection molding machine with a 150T vent manufactured by Japan Steel Works, Ltd. using a high-rigidity thermoplastic resin under the following conditions: width 60 mm × length 260
mm test pieces were obtained.

Injection molding temperature (cylinder temperature setting) 230 ° C. Mold temperature (cooling water temperature setting) 40 ° C. The cross-sectional shape of each of these test pieces taken along a plane parallel to the plate thickness direction and the width direction is as shown in FIG. 1 to 9 (a), (b), (c), (d), (e), (f),
There were 9 types, (g), (h) and (i). The cross-sectional dimensions are indicated by numbers in each figure.

Then, the flat surface of the test piece was brought into close contact with the mold, and a space of 60 mm in width × 260 mm in length × 6 mm in thickness was filled so that the low-rigidity thermoplastic resin was newly filled in the space of the uneven surface on the opposite side. I attached it to the mold. Then, a low-rigidity thermoplastic resin is filled under the same conditions with the same injection molding machine as described above, and (a '), (b'), (c '), (d') shown in FIGS.
A laminated molded body of (e ′), (f ′), (g ′), (h ′) and (i ′) having a width of 60 mm × a length of 260 mm × a thickness of 6 mm was obtained. 10 to 18, the black portion is a high-rigidity thermoplastic resin and the white portion is a low-rigidity thermoplastic resin.

(B) Method for Observing Warpage of Molded Product The laminated molded product obtained as described above is placed on a horizontal plate 48 hours after the molding, and placed on a horizontal plane so that one surface of the lower face of the laminated molded product is examined. The distance apart was measured.

[0039]

[Table 1]

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a high-rigidity thermoplastic resin molded body of a comparative example.

FIG. 2 is a cross-sectional view of a high-rigidity thermoplastic resin molded body of an example.

FIG. 3 is a cross-sectional view of a high-rigidity thermoplastic resin molded body of a comparative example.

FIG. 4 is a cross-sectional view of a high-rigidity thermoplastic resin molded body of an example.

FIG. 5 is a cross-sectional view of a high-rigidity thermoplastic resin molded body of an example.

FIG. 6 is a cross-sectional view of a high-rigidity thermoplastic resin molded body of an example.

FIG. 7 is a cross-sectional view of a high-rigidity thermoplastic resin molded body of an example.

FIG. 8 is a cross-sectional view of a high-rigidity thermoplastic resin molded body of an example.

FIG. 9 is a cross-sectional view of a high-rigidity thermoplastic resin molded body of an example.

FIG. 10 is a cross-sectional view of a plate-shaped laminated thermoplastic resin molded body of a comparative example.

FIG. 11 is a cross-sectional view of a plate-shaped laminated thermoplastic resin molding of the example.

FIG. 12 is a cross-sectional view of a plate-shaped laminated thermoplastic resin molded body of a comparative example.

FIG. 13 is a cross-sectional view of a plate-shaped laminated thermoplastic resin molding of the example.

FIG. 14 is a cross-sectional view of a plate-shaped laminated thermoplastic resin molding of the example.

FIG. 15 is a cross-sectional view of a plate-shaped laminated thermoplastic resin molded body of the example.

FIG. 16 is a cross-sectional view of a plate-shaped laminated thermoplastic resin molded body of the example.

FIG. 17 is a cross-sectional view of a plate-shaped laminated thermoplastic resin molding of the example.

FIG. 18 is a cross-sectional view of a plate-shaped laminated thermoplastic resin molded body of the example.

Claims (1)

[Claims] 1. A plate-shaped molded body, in which two kinds of thermoplastic resins having different bending elastic moduli and a bending elastic modulus ratio of 0.5 or less are laminated, and which is parallel to the plate thickness direction. The boundary between two types of thermoplastic resin in at least one cross section cut in step 3 has unevenness, and the cross sections satisfy the following expressions (1) and (2) at the same time. Plastic resin molding. 0.2 <B / A ≦ 1.6 (1) 0.5 ≦ (C × I) / (A × I ′) <1 (2) (In the above formula, A: Cross-sectional area occupied by a thermoplastic resin having a high flexural modulus B: Cross-sectional area occupied by a thermoplastic resin having a low flexural modulus C: Total cross-sectional area of a plate-shaped laminated thermoplastic resin molding I: High flexural modulus The second moment of area of the thermoplastic resin having a high flexural modulus with respect to an axis passing through the center of the thermoplastic resin and perpendicular to the plate thickness direction and existing in the cross section I ': Diagram of the laminated thermoplastic resin sheet The second moment of area of the plate-shaped laminated thermoplastic resin molding with respect to an axis passing through the center and perpendicular to the plate thickness direction and existing in the cross section.)