JP2023003058A - Plate-like molded body - Google Patents

Abstract

To provide a plate-like molded body in which warpage is suppressed.SOLUTION: There is provided a plate-like molded body that is made of a liquid crystal polyester, and that comprises a plate-like base, a plurality of front ribs and a plurality of back ribs, and that satisfies a formula (1) below. The molded body is configured in that: the base is belt-shaped extending in one direction; the plurality of front ribs includes a first rib projecting from a front surface and a pair of ribs sandwiching the first rib; the plurality of back ribs includes a second rib protruding from a back surface; the second rib is located in a range from a center of the first rib and one of the pair of ribs to the center of the first rib and the other of the pair of ribs in a plan view, and is not parallel to the first rib; a volume of the first rib is 70% or more and 130% or less of a volume of the second rib; and the plurality of front ribs and back ribs intersect an extending direction of the base. Formula (1): |(sinA1+sinA2+...+sinAx)-(sinB1+sinB2+...+sinBy)|≤1, where x is the number of front ribs, y is the number of back ribs, Ax is an angle between the front rib and an imaginary line perpendicular to the extending direction in a plan view, and By is an angle between the imaginary line and the back rib.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a plate-shaped compact.

A molded article using a liquid crystal polymer as a forming material has high strength, high heat resistance, and high dimensional accuracy. Therefore, liquid crystal polymers are used as materials for forming relatively small electronic parts such as connectors and relay parts (see, for example, Patent Document 1).

JP-A-07-126383

In recent years, taking advantage of the features described above, liquid crystal polymers have been used as materials for plate-shaped moldings in addition to the materials for small electronic components as described above. In the following description, a “plate-like” molded body refers to a molded body whose height in front view is lower than in plan view. For example, in a compact that is inscribed in a rectangular parallelepiped (a<b<c) having three sides of a (height), b (vertical), and c (horizontal), b is 10 times or more of a. The molded product corresponds to the “plate-shaped molded product” in the above definition.

Liquid crystal polymers are known to be easily oriented in the direction of flow when melted. A molded body made of a liquid crystal polymer has a different amount of curing shrinkage due to the orientation of the resin, and may warp. Therefore, in the plate-like molding made of liquid crystal polymer, it is necessary to devise ways to suppress warping.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a plate-like formed article in which warpage is suppressed.

A plate-like molded body is sometimes thinned for weight reduction. On the other hand, when the thickness of the plate-like molded body is reduced, the rigidity and strength tend to decrease. Therefore, in order to supplement the strength of the plate-like molded body, a "rib" is sometimes provided on the plate-shaped molded body. For example, a plurality of such ribs may be arranged in one direction on one surface of the plate-like compact.

As a result of investigations by the inventors, it was found that when ribs are provided in a plate-like molding made of a liquid crystal polymer, warpage is likely to occur, and that countermeasures are necessary. In addition, the inventors' studies have revealed that such warpage is significantly greater than in the case of forming a plate-like molding using other thermoplastic resins. From these, the warpage of the molded article is considered to be a problem specific to the liquid crystal polymer material.
As a result of intensive studies by the inventor, the following invention was completed in consideration of the properties of the liquid crystal polymer.

In order to solve the above problems, one aspect of the present invention includes the following aspect.

[1] Made of liquid crystal polyester, comprising a plate-shaped base, a plurality of front ribs provided on the front surface of the base, and a plurality of back ribs provided on the back of the base, The base portion has a strip shape extending in one direction, and the plurality of front ribs include a first rib projecting from the front surface and a pair of ribs projecting from the front surface at positions sandwiching the first rib. and, wherein the plurality of back ribs includes a second rib projecting from the back surface, and the second rib extends from the center of the first rib and one of the pair of ribs in plan view. The first rib is positioned between the first rib and the center of the other of the pair of ribs, is not parallel to the first rib, and the volume of the first rib is 70% or more and 130% or less of the volume of the second rib. wherein the plurality of front ribs and the plurality of back ribs intersect the direction in which the base extends, and satisfy the following formula (1).
|(sinA ₁ +sinA ₂ +...+sinA _x )-(sinB ₁ +sinB ₂ +...+sinB _y )|≤1...(1) (where x is the number of front ribs, y is the number of back ribs, A _x is the angle between the front rib and an imaginary line orthogonal to the extending direction in plan view, and B _y is the angle between the imaginary line and the back rib).

[2] The plate-shaped compact according to [1], wherein the angle formed by the first rib and the second rib is more than 0° and 4° or less in plan view.

[3] Made of liquid crystal polyester, comprising a plate-shaped base, a plurality of front ribs provided on the front surface of the base, and a plurality of back ribs provided on the back of the base, The plurality of front ribs includes a first rib projecting from the front surface and a pair of ribs projecting from the front surface at positions sandwiching the first rib, and the plurality of back ribs are A second rib protruding from the back surface is included, and the second rib extends from the center of the first rib and one of the pair of ribs to the other of the pair of ribs in plan view. The volume of the first rib is 70% or more and 130% or less of the volume of the second rib, and the angle formed by the first rib and the second rib in plan view is , 0° or more and 4° or less.

[4] The plate-shaped molding according to [3], wherein the base is a strip extending in one direction, and the plurality of front ribs and the plurality of back ribs are provided to intersect the direction in which the base extends. body.

[5] The plate-like compact according to [4], which satisfies the following formula (1).
|( _sinA1 +sinA2 ₊ ...+ _sinAx )-( _sinB1 +sinB2 ₊ ...+ _sinBy )|≤1...(1)
(Wherein, x is the number of the front ribs, y is the number of the back ribs, A _x is the angle between the front ribs and an imaginary line perpendicular to the extending direction in plan view, B _y is the imaginary line and the showing the angle with the back rib)

[6] The plate-shaped compact according to any one of [3] to [5], wherein the first rib and the second rib are parallel in plan view.

[7] The plate-like compact according to any one of [1] to [6], wherein the first rib and the second rib overlap in plan view.

ADVANTAGE OF THE INVENTION According to this invention, the plate-shaped molded object with which curvature was suppressed can be provided.

FIG. 1 is a schematic perspective view of a plate-shaped compact 1. FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1. FIG. 3A and 3B are explanatory diagrams for explaining problems in forming a plate-like molded body having ribs on the surface thereof, using liquid crystal polyester as a material. FIG. 4 is an explanatory diagram for explaining equation (1). FIG. 5 is a diagram showing a flow analysis model used in the simulation of the example. FIG. FIG. 11 is a scatter diagram showing the correspondence between |xsinA−ysinB| and flatness for 11 to 18 samples.

The plate-shaped molding of this embodiment is made of liquid crystal polyester and has the following characteristics.
(i) A plate-like base, a plurality of front ribs provided on the front surface of the base, and a plurality of back ribs provided on the back surface of the base.
(ii) The plurality of front ribs includes a first rib projecting from the front surface and a pair of ribs projecting from the front surface at positions sandwiching the first rib.
(iii) The plurality of back ribs includes second ribs protruding from the back surface.
(iv) The second rib is located in a range from the center of the first rib and one of the pair of ribs to the center of the first rib and the other of the pair of ribs in plan view.

Furthermore, in addition to the above (i) to (iv), the plate-shaped compact of the present embodiment has the following features (v) or (vi).
(v) The base is strip-shaped and extends in one direction, and the plurality of front ribs and the plurality of back ribs are provided to intersect the direction in which the base extends, satisfying the following formula (1).
|( _sinA1 +sinA2 ₊ ...+ _sinAx )-( _sinB1 +sinB2 ₊ ...+ _sinBy )|≤1...(1)
(Wherein, x is the number of the front ribs, y is the number of the back ribs, A _x is the angle between the front ribs and an imaginary line perpendicular to the extending direction in plan view, B _y is the imaginary line and the showing the angle with the back rib)
(vi) In plan view, the angle formed by the first rib and the second rib is 0° or more and 4° or less.
They will be explained in order below.

A plate-shaped compact according to an embodiment of the present invention will be described below with reference to FIGS. 1 to 4. FIG. In addition, in all the drawings below, the dimensions and ratios of the constituent elements are appropriately changed in order to make the drawings easier to see.

1 and 2 are explanatory diagrams showing the plate-shaped molded body of this embodiment. FIG. 1 is a schematic perspective view of the plate-shaped molded body 1, and FIG. It is a cross-sectional view.

As shown in FIGS. 1 and 2 , the plate-like molded body 1 includes a belt-like base portion 10 , a plurality of front ribs 20 and a plurality of back ribs 30 .

In the following description, an xyz orthogonal coordinate system is set, and the positional relationship of each member will be described with reference to this xyz orthogonal coordinate system. Here, the direction in which the base 10 extends in the horizontal plane is the x-axis direction, the direction perpendicular to the x-axis direction in the horizontal plane is the y-axis direction, and the direction perpendicular to each of the x-axis direction and the y-axis direction (that is, the vertical direction) is Let it be in the z-axis direction.

A plate-like molded body 1 shown in FIG. 1 has a simplified shape for easy explanation of the present invention.

The plate-like molded body 1 is an injection molded body made of liquid crystal polyester. The plate-like molded body 1 has a gate mark G at the one end 10c in the longitudinal direction of the base 10 at the time of injection molding.

A specific member to which the plate-like formed body 1 is applied is, for example, a known guide plate for a laser printer. The surface of the guide plate has a plurality of ribs along the paper feed direction for reducing the contact area with the print paper.

(liquid crystal polyester)
The liquid crystalline polyester used in this embodiment is one of thermotropic liquid crystalline polymers, and can form a melt exhibiting optical anisotropy at a temperature of 450° C. or less.

The liquid crystal polyester preferably has a repeating unit represented by the following general formula (1) (hereinafter sometimes referred to as "repeating unit (1)"), and the repeating unit (1) and the following general formula (2 ) (hereinafter sometimes referred to as “repeating unit (2)”) and a repeating unit represented by the following general formula (3) (hereinafter referred to as “repeating unit (3)”) It is more preferable to have

(1) —O—Ar ¹ —CO—
(2) -CO-Ar2 ^- CO-
(3) -X-Ar ³ -Y-
(wherein Ar ¹ represents a phenylene group, a naphthylene group or a biphenylylene group; Ar ² and Ar ³ each independently represent a phenylene group, a naphthylene group, a biphenylylene group or a group represented by the following general formula (4); X and Y each independently represent an oxygen atom or an imino group (—NH—) One or more hydrogen atoms in the groups represented by Ar ¹ , Ar ² or Ar ³ each represent may be independently substituted with a halogen atom, an alkyl group, or an aryl group.)

(4) —Ar ⁴ —Z—Ar ⁵ —
(In the formula, Ar ⁴ and Ar ⁵ each independently represent a phenylene group or a naphthylene group.
Z represents an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group or an alkylidene group. )

Specifically, the liquid crystalline polyester used in this embodiment includes:
(1) those obtained by polymerizing a combination of an aromatic hydroxycarboxylic acid, an aromatic dicarboxylic acid, and an aromatic diol;
(2) those obtained by polymerizing multiple types of aromatic hydroxycarboxylic acids;
(3) obtained by polymerizing a combination of an aromatic dicarboxylic acid and an aromatic diol;
(4) those obtained by reacting a crystalline polyester such as polyethylene terephthalate with an aromatic hydroxycarboxylic acid;

Part or all of the aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid and aromatic diol used as raw material monomers in the production of the liquid crystalline polyester may be preliminarily converted into ester-forming derivatives and subjected to polymerization. By using such an ester-forming derivative, there is an advantage that the liquid crystalline polyester can be produced more easily.

Examples of ester-forming derivatives are as follows.

Examples of ester-forming derivatives of aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids having a carboxyl group in the molecule include haloformyl groups (acid halides) and acyloxycarbonyl groups (acid anhydrides) where the carboxyl group is Those converted to highly reactive groups, and the carboxyl groups formed esters with monohydric alcohols, polyhydric alcohols such as ethylene glycol, phenols, etc. so as to produce polyesters by transesterification. things are mentioned.

Examples of polymerizable derivatives of compounds having phenolic hydroxyl groups such as aromatic hydroxycarboxylic acids and aromatic diols include lower carboxylic acids and esters such that the phenolic hydroxyl groups produce polyesters through transesterification reactions. are formed.

Furthermore, the aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid or aromatic diol described above has a chlorine atom, a halogen atom such as a fluorine atom, a methyl group, an ethyl and an alkyl group having 1 to 10 carbon atoms such as a butyl group; and an aryl group having 6 to 20 carbon atoms such as a phenyl group as a substituent.

Examples of aromatic hydroxycarboxylic acids include p-hydroxybenzoic acid, m-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 3-hydroxy-2-naphthoic acid, 5-hydroxy-1-naphthoic acid, 4 -hydroxy-4'-carboxydiphenyl ether. In addition, some of the hydrogen atoms in the aromatic rings of these aromatic hydroxycarboxylic acids are substituted with one or more substituents selected from the group consisting of alkyl groups, aryl groups and halogen atoms. acid.

p-Hydroxybenzoic acid is an aromatic hydroxycarboxylic acid from which (A ₁ ) described below is derived.

6-Hydroxy-2-naphthoic acid is an aromatic hydroxycarboxylic acid from which (A ₂ ) described below is derived.

The aromatic hydroxycarboxylic acid may be used singly or in combination of two or more in the production of the liquid crystalline polyester.

The repeating unit (1) described above is a repeating unit derived from a predetermined aromatic hydroxycarboxylic acid. Examples of repeating units derived from aromatic hydroxycarboxylic acids include those shown below. In the repeating unit derived from an aromatic hydroxycarboxylic acid, some of the hydrogen atoms on the aromatic ring are substituted with one or more substituents selected from the group consisting of halogen atoms, alkyl groups and aryl groups. may

As used herein, the term "derived" means that the chemical structure is changed due to the polymerization of the raw material monomer, and no other structural change occurs.

Examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, biphenyl-4,4′-dicarboxylic acid, 2,6-naphthalenedicarboxylic acid, diphenyl ether-4,4′-dicarboxylic acid, and diphenylthioether-4,4′. - dicarboxylic acids. Also, aromatic dicarboxylic acids in which some of the hydrogen atoms in the aromatic rings of these aromatic dicarboxylic acids are substituted with one or more substituents selected from the group consisting of alkyl groups, aryl groups and halogen atoms. mentioned.

Terephthalic acid is an aromatic dicarboxylic acid from which (B ₁ ) described below is derived.

Isophthalic acid is an aromatic dicarboxylic acid from which (B ₂ ) described later is derived.

2,6-naphthalenedicarboxylic acid is an aromatic dicarboxylic acid from which (B ₃ ) described later is derived.

The aromatic dicarboxylic acids may be used singly or in combination of two or more in the production of the liquid crystalline polyester.

The repeating unit (2) described above is a repeating unit derived from a predetermined aromatic dicarboxylic acid. Examples of repeating units derived from aromatic dicarboxylic acids include those shown below. In the repeating unit derived from an aromatic dicarboxylic acid, some of the hydrogen atoms on the aromatic ring are substituted with one or more substituents selected from the group consisting of halogen atoms, alkyl groups and aryl groups. good too.

Examples of aromatic diols include 4,4'-dihydroxybiphenyl, hydroquinone, resorcinol, 4,4'-dihydroxydiphenyl ketone, 4,4'-dihydroxydiphenyl ether, bis(4-hydroxyphenyl)methane, 1,2- bis(4-hydroxyphenyl)ethane, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenylthioether, 2,6-dihydroxynaphthalene, 1,5-dihydroxynaphthalene. Also included are aromatic diols in which some of the hydrogen atoms in the aromatic rings of these aromatic diols are substituted with one or more substituents selected from the group consisting of alkyl groups, aryl groups and halogen atoms. .

4,4′-dihydroxybiphenyl is an aromatic diol from which (C ₁ ) described later is derived.

Hydroquinone is an aromatic diol from which (C ₂ ) described later is derived.

Resorcinol is an aromatic diol from which (C ₃ ) described below is derived.

The aromatic diols may be used singly or in combination of two or more in the production of the liquid crystalline polyester.

The repeating unit (3) described above includes repeating units derived from a predetermined aromatic diol. Examples of repeating units derived from aromatic diols include those shown below. In the repeating unit derived from an aromatic diol, some of the hydrogen atoms on the aromatic ring may be substituted with one or more substituents selected from the group consisting of halogen atoms, alkyl groups and aryl groups. good.

In the substituent that the repeating unit (a repeating unit derived from an aromatic hydroxycarboxylic acid, a repeating unit derived from an aromatic dicarboxylic acid, a repeating unit derived from an aromatic diol) may optionally have, the halogen atom Examples include fluorine atom, chlorine atom, and bromine atom. Examples of alkyl groups include lower alkyl groups having about 1 to 4 carbon atoms such as methyl group, ethyl group, and butyl group. Examples include phenyl groups.

A particularly preferred liquid crystalline polyester will be described.
The repeating unit derived from an aromatic hydroxycarboxylic acid includes a repeating unit derived from parahydroxybenzoic acid ((A ₁ )) or a repeating unit derived from 2-hydroxy-6-naphthoic acid or both ((A ₂ ) ).

Examples of repeating units derived from aromatic dicarboxylic acids include repeating units derived from terephthalic acid ((B ₁ )), repeating units derived from isophthalic acid ((B ₂ )), and 2,6-naphthalenedicarboxylic acid ((B ₃ ) It is preferable to have a repeating unit selected from the group consisting of repeating units derived from )).

The repeating unit derived from the aromatic diol has a repeating unit ((C ₂ )) derived from hydroquinone or a repeating unit ((C ₁ )) derived from 4,4'-dihydroxybiphenyl or both. and preferred.

As these combinations, those represented by the following (a) to (h) are preferable. A combination of repeating units (a) to (h) yields a liquid crystalline polyester having good electrical insulation.

(a): a combination consisting of (A ₁ ), (B ₁ ) and (C ₁ ), or a combination consisting of (A ₁ ), (B ₁ ), (B ₂ ) and (C ₁ ).
(b): a combination consisting of (A ₂ ), (B ₃ ) and (C ₂ ), or a combination consisting of (A ₂ ), (B ₁ ), (B ₃ ) and (C ₂ ).
(c): a combination consisting of (A ₁ ) and (A ₂ ).
(d): A combination of repeating units of (a) in which part or all of (A ₁ ) is replaced with (A ₂ ).
(e): A combination of repeating units of (a) in which (B ₁ ) is partially or wholly replaced with (B ₃ ).
(f): A combination of repeating units of (a) in which (C ₁ ) is partially or wholly replaced with (C ₃ ).
(g): A combination of repeating units of (b) in which (A ₂ ) is partially or wholly replaced with (A ₁ ).
(h): A combination of repeating units of (c) plus (B ₁ ) and (C ₂ ).

A particularly preferred liquid crystalline polyester has a total number of repeating units derived from an aromatic hydroxycarboxylic acid of 30 to 80% and a total of repeating units derived from an aromatic diol of 10 to 100%, based on the total number of all repeating units. 35%, and the total of repeating units derived from aromatic dicarboxylic acids is 10-35%.

As a method for producing the liquid crystalline polyester, for example, a known method such as the method described in JP-A-2002-146003 can be applied. That is, the above raw material monomers (aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid, aromatic diol, or ester-forming derivative thereof) are melt-polymerized (polycondensation) to obtain a relatively low-molecular-weight aromatic polyester (hereinafter referred to as (abbreviated as "prepolymer") is obtained, then this prepolymer is pulverized and heated to carry out solid phase polymerization. By carrying out solid phase polymerization in this manner, the polymerization proceeds further, and a liquid crystalline polyester having a higher molecular weight can be obtained.

In addition, for the method for producing a liquid crystalline polyester having a combination of repeating units (a) and (b), which are the most basic structures, see Japanese Patent Publication No. 47-47870, Japanese Patent Publication No. 63-3888, etc. Have been described.

The melt polymerization may be carried out in the presence of a catalyst, examples of which include metals such as magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, potassium acetate, antimony trioxide. and nitrogen-containing heterocyclic compounds such as 4-(dimethylamino)pyridine and 1-methylimidazole, and nitrogen-containing heterocyclic compounds are preferably used.

As the liquid crystalline polyester used for the plate-like molding, it is preferable to use a liquid crystalline polyester having a flow initiation temperature of 280° C. or higher as determined by the following method. As described above, when solid phase polymerization is used in the production of liquid crystalline polyester, it is possible to raise the flow initiation temperature of liquid crystalline polyester to 280° C. or higher in a relatively short period of time. By using a liquid crystalline polyester having such a flow initiation temperature, the obtained molded article has a high degree of heat resistance. On the other hand, from the viewpoint of molding the molded article within a practical temperature range, the flow initiation temperature of the liquid crystalline polyester used for the plate-like molded article is preferably 420° C. or lower, more preferably 390° C. or lower.

Here, the flow initiation temperature is defined by using a capillary rheometer equipped with a die having an inner diameter of 1 mm and a length of 10 mm, and applying a load of 9.8 MPa (100 kg/cm ² ) at a heating rate of 4° C./min to the liquid crystalline polyester. is the temperature at which the melt viscosity exhibits 4800 Pa·s (48000 poise) when extruded from a nozzle. The flow initiation temperature is an index representing the molecular weight of a liquid crystalline polyester well known in the art (Edited by Naoyuki Koide, "Synthesis, Molding and Application of Liquid Crystalline Polymers", pp. 95-105, CMC, June 1987. 5th issue). As an apparatus for measuring the flow initiation temperature, for example, a flow characteristic evaluation apparatus "Flow Tester CFT-500D" manufactured by Shimadzu Corporation can be used.

[Filling material]
The plate-shaped compact 1 of this embodiment may contain a filler. In this embodiment, since the plate-shaped molded body 1 contains a filler, it is possible to impart sufficient strength to the plate-shaped molded body 1 .

The filler used in this embodiment may be an inorganic filler or an organic filler. Further, it may be a fibrous filler, a plate-like filler, or a granular filler.

Examples of fibrous fillers include glass fibers; carbon fibers such as bread-based carbon fibers and pitch-based carbon fibers; ceramic fibers such as silica fibers, alumina fibers and silica-alumina fibers; and metal fibers such as stainless steel fibers. . Also included are whiskers such as potassium titanate whiskers, barium titanate whiskers, wollastonite whiskers, aluminum borate whiskers, silicon nitride whiskers, and silicon carbide whiskers.

Examples of platy fillers include talc, mica, graphite, wollastonite, barium sulfate and calcium carbonate. The mica may be muscovite, phlogopite, fluorine phlogopite, or tetrasilicon mica.

Examples of particulate fillers include silica, alumina, titanium oxide, boron nitride, silicon carbide and calcium carbonate.

A laser printer, which is one application of the plate-shaped molded body 1, electrostatically adheres powdery toner to the surface of printing paper, and then presses the toner against the paper at high temperature and high pressure to fuse it to the paper. Print. The guide plate contacts the printing paper heated to a high temperature. Therefore, liquid crystal polyester, which has high strength (high rigidity) and heat resistance, is suitable as a material for the guide plate.

On the other hand, liquid crystalline polyester is known to be easily oriented in the direction of flow when melted. Molded bodies made of liquid crystalline polyester have different amounts of curing shrinkage due to the orientation of the resin. Specifically, the liquid crystalline polyester shrinks more in the direction crossing the alignment direction than in the alignment direction. Therefore, when a plate-like molded article having ribs on the surface thereof is formed using liquid crystalline polyester as a material, the following problems occur.

FIG. 3 is an explanatory diagram for explaining problems in molding a plate-shaped molded body having ribs on the surface thereof, and is a partially enlarged view showing how the plate-shaped molded body is manufactured. A plate-like molded body 1X shown in FIG. 3 has a shape obtained by removing the back rib 30 from the plate-shaped molded body 1 of FIG. The rib 29 is provided so as to protrude from the base portion 10 and extends in the width direction of the base portion 10 .

When molding such a plate-like molding 1X by injection molding, the molten resin R is injected into the cavity C1 of the mold M from a gate corresponding to one end of the base portion 10. As shown in FIG. In the mold M, the molten resin R first flows along the extending direction of the base portion 10 . In FIG. 3, the molten resin flowing in this manner is denoted by symbol R1.

Next, the molten resin R flows into the recesses C2 corresponding to the ribs 29 in the mold M. As shown in FIG. At that time, the molten resin R flows in a direction crossing the base portion 10 (a direction away from the base portion 10). In FIG. 3, the molten resin that flows in this manner is denoted by symbol R2.

The molten resin R then reaches the bottom C3 of the recess C2 corresponding to the top surface of the rib 29 . The molten resin R that has reached the bottom portion C3 flows along the bottom portion C3, that is, along the direction in which the ribs 29 extend. In FIG. 3, the molten resin that flows in this manner is denoted by symbol R3.

In the plate-shaped molded body 1X thus molded, the molten resin R1 is oriented in the x-axis direction, while the molten resin R2 is oriented in the z-axis direction. Therefore, in the x-axis direction, the shrinkage of the base portion 10 obtained by solidifying the molten resin R1 is small, whereas the shrinkage of the ribs 29 obtained by solidifying the molten resin R2 is large.

As a result, shrinkage caused by the ribs 29 is considered to occur in the plate-shaped compact 1X. Specifically, it is considered that the plate-like formed body 1X is warped in the longitudinal direction so as to be convex in the −z-axis direction.

Further, in the plate-shaped molding 1X, the molten resin R1 is oriented in the x-axis direction, while the molten resin R3 is oriented in the y-axis direction. Therefore, in the y-axis direction, the shrinkage of the tips of the ribs 29 obtained by solidifying the molten resin R3 is small, whereas the shrinkage of the bases 10 obtained by solidifying the molten resin R1 is large.

As a result, shrinkage caused by the base portion 10 is considered to occur in the plate-like molded body 1X. Specifically, it is considered that the plate-like compact 1X is warped convexly in the +z-axis direction in the lateral direction.

The above-described warp caused by the orientation of the molten resin is conspicuous particularly when a plate-like molding is formed by injection molding using a liquid crystalline polyester as a material. Therefore, when manufacturing a plate-like molding using a material that is relatively difficult to align compared to liquid crystalline polyester, even if there is no problem, by using liquid crystalline polyester as a material, it is possible to design the structure in more detail. need to do.

As a result of intensive studies, the inventors have found that warping can be reduced by using a structure like the plate-shaped molding 1 of the present embodiment.

1 and 2 includes a plate-shaped base 10, a plurality of front ribs 20 provided on the front surface 10a of the base 10, and a plurality of ribs 20 provided on the back surface 10b of the base 10. a back rib 30;

The base portion 10 occupies most of the plate-shaped compact 1 . The base 10 has a strip shape extending in one direction and presents a rectangular shape in plan view. One end 10c of the base 10 has a gate mark G. As shown in FIG. “Planar view” refers to the field of view seen from the +z-axis side.

Here, the term “belt-shaped” is an expression indicating a state of being elongated in one direction. In this sense, the planar shape of the “band-like” base 10 is not limited to a mathematical rectangle. Moreover, in plan view, the sides of the base 10 may not be linear.

The gate mark G at the position as described above means that the plate-shaped compact 1 was injection molded using a mold having a gate set at one end 10c in the longitudinal direction. By molding in this way, the molten resin of the liquid crystalline polyester is easily oriented in the longitudinal direction during injection molding, and the resulting molded product can be maintained with high dimensional accuracy in the longitudinal direction.

A mold used for injection molding of the plate-shaped molded body 1 has an internal space (cavity) that complementarily overlaps with the plate-shaped molded body 1 . The mold has a gate at a position biased toward one end in the longitudinal direction of the cavity. The gate is positioned in the longitudinal direction of the cavity so that the distance from the longitudinal end of the cavity to the gate is 10% or less of the longitudinal length L of the cavity (0.1 L or less from the end). is provided. The plate-shaped compact 1 molded using such a mold has a gate mark G at a position that is 10% or less of the length in the longitudinal direction.

The distance from the center of the gate to the longitudinal end of the cavity is preferably 8% or less, more preferably 6% or less, and preferably 4% or less of the longitudinal length of the cavity. More preferred.

Although the gate mark G is circular in FIG. 1, it is not limited to this. The shape of the gate mark G corresponds to the cross-sectional shape of the gate of the mold used, and the cross-sectional shape of the gate may be circular, semicircular, elliptical, square, rectangular (rectangular), trapezoidal, or similar. It may be a known shape such as For example, the gate may be a film gate extending along one short side of the cavity.

The thickness T of the base 10 is preferably 0.1 mm or more, more preferably 0.3 mm or more. Also, the thickness T of the base 10 is preferably 5 mm or less, more preferably 3 mm or less.
The upper limit and lower limit of the thickness T can be combined arbitrarily.

A plurality of front ribs 20 are provided to intersect the extending direction (x-axis direction) of the base portion 10 . The front rib 20 extends in the y-axis direction. Although the plurality of front ribs 20 are parallel to each other in plan view in FIG. 1 , the present invention is not limited to this.

The intervals between adjacent front ribs 20 may be equal or different. The interval between the front ribs 20 is preferably 1 mm or more, more preferably 2 mm or more. Also, the interval between the front ribs 20 is preferably 100 mm or less, more preferably 50 mm or less.
The upper limit and lower limit of the interval between the front ribs 20 can be combined arbitrarily.

The plurality of front ribs 20 includes a first rib 21 projecting from the front surface 10a and a pair of ribs (ribs 22 and 23) projecting from the front surface 10a at positions sandwiching the first rib 21. include. The first rib 21 is any one of the plurality of front ribs 20 . The pair of ribs 22 and 23 are ribs adjacent to the first rib 21 .

A plurality of back ribs 30 are provided to intersect the direction in which the base 10 extends (the x-axis direction). The back rib 30 extends in the y-axis direction. In FIG. 1, the plurality of back ribs 30 are parallel to each other in a plan view, but the invention is not limited to this.

The intervals between adjacent back ribs 30 may be equal or different. The interval between the back ribs 30 is preferably 1 mm or more, more preferably 2 mm or more. The interval between the back ribs 30 is preferably 100 mm or less, more preferably 50 mm or less.
The upper limit and lower limit of the interval between the back ribs 30 can be arbitrarily combined.

The plurality of back ribs 30 include second ribs 31 projecting from the back surface 10b. The second rib 31 is positioned in a range AR from the center position between the first ribs 21 and 22 to the center position between the first ribs 21 and 23 in plan view.

In addition, the “center position between the first rib 21 and the rib 22” means the center between the center line of the first rib 21 and the center line of the rib 22 in plan view. Further, "the center position between the first rib 21 and the rib 23" means the center between the center line of the first rib 21 and the center line of the rib 23 in plan view.

The front rib 20 may be warped or distorted due to the difference in the amount of shrinkage depending on the flow direction of the molten resin, as described with reference to FIG. On the other hand, like the front ribs 20, the back ribs 30 may also be warped or distorted due to the difference in the amount of shrinkage depending on the flow direction of the molten resin. Since the plate-like formed body 1 has the front rib 20 and the back rib 30, the strains generated in the front rib 20 and the back rib 30 cancel each other out. As a result, the plate-like molded body 1 can reduce warpage as the molded body as a whole.

More specifically, by providing the second ribs 31 (rear ribs 30) at the above-described positions, the second ribs 31 effectively cancel out the distortion caused by the first ribs 21 and reduce the warpage of the compact. be able to.

The first rib 21 and the second rib 31 shown in FIGS. 1 and 2 are provided at overlapping positions in plan view.

Moreover, the plurality of ribs included in the front rib 20 and the plurality of ribs included in the back rib 30 include the first ribs 21 and the second ribs 31 that are not parallel in plan view. It is preferable that the first rib 21 and the second rib 31 form an angle of more than 0° and 4° or less in plan view. The above-mentioned "formed angle" may be 3° or less, or may be 2° or less.

The ribs other than the first ribs 21 included in the front rib 20 and the ribs other than the second ribs 31 included in the back rib 30 may be parallel in plan view.

1 and 2, the front ribs 20 and the back ribs 30 extend in a direction (y-axis direction) perpendicular to the direction in which the base portion 10 extends (x-axis direction). there is The direction in which the front rib 20 and the back rib 30 extend with respect to the direction in which the base 10 extends is not limited to the relationship shown in the drawing. However, depending on the angles of the front ribs 20 and the back ribs 30 with respect to the base 10, the warpage of the plate-like molded body 1 may rather be increased.

As a result of examination by the inventors, it was found that in the plate-like formed body of the present embodiment, the front rib 20 and the back rib 30 can appropriately reduce warping by satisfying the following formula (1). .
|( _sinA1 +sinA2 ₊ ...+ _sinAx )-( _sinB1 +sinB2 ₊ ...+ _sinBy )|≤1...(1)
(Wherein, x is the number of front ribs, y is the number of back ribs, A _x is the angle between the front rib and an imaginary line perpendicular to the direction in which the base extends in plan view, B _y is the direction in which the base extends in plan view. shows the angle between the virtual line perpendicular to the and the back rib)

If all A _x are the same angle A and all B _y are the same angle B, the above equation (1) can be transformed as follows.
|x sin A−y sin B|≦1 (1)−1
(Wherein, x is the number of front ribs, y is the number of back ribs, A is the angle between the virtual line perpendicular to the direction in which the base extends in plan view and the front rib, and B is perpendicular to the direction in which the base extends in plan view. shows the angle between the virtual line and the back rib)

FIG. 4 is an explanatory diagram for explaining the above (1), and is a schematic plan view of the plate-like compact 1A. The plate-shaped compact 1A has a base 10, front ribs 20, and back ribs 30, and the angles of the front ribs 20 and back ribs 30 with respect to the base 10 are different from those of the plate-shaped compact 1 shown in FIGS. is.

An angle A shown in FIG. 4 is an angle formed between the front rib 20 and an imaginary line L perpendicular to the extending direction (x-axis direction) of the base portion 10 in plan view. The angle A is defined as a + (positive) angle at which the imaginary line L rotates counterclockwise (counterclockwise) about the intersection point P between the imaginary line L and one side 10x of the base 10 in plan view.

Similarly, the angle B is the angle between the back rib 30 and an imaginary line L perpendicular to the extending direction (x-axis direction) of the base 10 in plan view. The angle B is defined as a + (positive) angle at which the imaginary line L rotates counterclockwise (counterclockwise) about the intersection point P between the imaginary line L and the side 10x of the base 10 in plan view.

In FIG. 4, for ease of explanation, the base 10 has a rectangular shape extending in the x-axis direction, and the front ribs 20 and the back ribs 30 have parallel sides extending in the direction intersecting the x-axis in plan view. is shown as

In actual design, if the base 10 is not rectangular, a minimum rectangle that circumscribes the base 10 in plan view is assumed, and the "extending direction of the base 10" is defined as the direction in which the long sides of the rectangle extend.

When both sides of the front rib 20 are not parallel, the center line of the front rib 20 is obtained as a set of midpoints of both sides of the front rib 20, and the intersection of the center line and one side 10x of the base 10 is defined as the intersection point P. . Also, a tangent line to the central line at the point of intersection P is obtained, and the angle between the tangent line and the virtual line L is defined as an angle A.

When both sides of the back rib 30 are not parallel, the center line of the back rib 30 is obtained as a set of midpoints of both sides of the back rib 30, and the intersection point of the center line and one side 10x of the base portion 10 is defined as the intersection point P. . Also, a tangent line to the central line at the point of intersection P is obtained, and the angle between the tangent line and the virtual line L is defined as an angle B.

As described above, the warp that occurs in the plate-like molding is the result of the curing shrinkage of the base portion 10 and the curing shrinkage of the ribs (front ribs and back ribs). Therefore, the number of ribs (the number of front ribs x, the number of back ribs y) is closely related to the warpage of the plate-like compact.

In addition, as described above, the warp of the plate-like molding is caused by the flow direction of the molten resin, that is, the orientation direction of the liquid crystal polyester. Therefore, the direction in which the ribs that define the flow direction of the molten resin are closely related to the warpage of the plate-like molding.

In the present invention, the relationship between the direction in which the base 10 extends (x-axis direction) and the direction in which the ribs extend is represented by the sine of the angle between the rib and an imaginary line L orthogonal to the direction in which the base extends. A simulation, which will be described later, has revealed that the sine of the angle between the imaginary line L and the rib has a correlation with the warp of the plate-like compact.

Further, when specifying the plate-shaped molded body of the present embodiment from another point of view, in the plate-shaped molded body of the present embodiment, the angle formed by the first rib 21 and the second rib 31 in plan view is 0° or more and 4 ° or less. It was found that when the angle formed by the first rib 21 and the second rib 31 is such an angle, the warp can be appropriately reduced.

The above-mentioned "formed angle" may be 3° or less, or may be 2° or less. Also, the "formed angle" may be 0°, that is, the first rib 21 and the second rib 31 may be parallel in plan view.

The warpage of the plate-like molded body may be determined by simulation, or may be determined by the following method by actually measuring the molded body.

The plate-like molded body is placed so as to protrude downward, and the three-dimensional shape of the plate-shaped molded body is determined from above using a three-dimensional measuring machine. Using the surface on which the plate-shaped compact is placed as a reference plane, coordinates are obtained at a plurality of points on the upper surface of the plate-shaped compact. Specifically, on each of both sides in the longitudinal direction of the plate-like molded body, the height of a total of five points (two points at both ends and three points at equal intervals between both ends (a total of 10 points on both sides)) is measured. demand. Next, a least-squares plane is calculated by the least-squares method for the heights of the 10 points obtained, and the height of the obtained least-squares plane from the reference plane is used as the flatness to be obtained.

The flatness can be determined by measuring the height at least two points at both ends and a total of six points at the center on both sides of the plate-like compact in the longitudinal direction.

The number of height measurement points may be increased according to the shape of the plate-like compact to be measured. In that case, the same measurement points should be used, and the number and positions of the measurement points should not be different between the compacts to be evaluated.

Further, the volume of each of the front ribs and the back ribs is closely related to the cure shrinkage amount of the ribs. Therefore, it is preferable that the volume difference between the front rib and the back rib, more specifically, the volume difference between the first rib and the second rib is small. The volume of the first ribs 21 is preferably 70% or more and 130% or less of the volume of the second ribs 31 . The volume of the first ribs 21 is more preferably 80% or more and 120% or less of the volume of the second ribs 31 , and more preferably 90% or more and 110% or less of the volume of the second ribs 31 .

According to the plate-like molded body having the above structure, the plate-shaped molded body is suppressed in warping.

In the present embodiment, the plate-shaped molding 1 having a simplified configuration was used for the sake of ease of explanation, but the member (plate-shaped molding) to which the present invention is applied may have other shapes. can also be adopted.
For example, in the plate-shaped compact 1, the first rib 21 and the second rib 31 are provided at positions overlapping each other in plan view, but the second rib 31 overlaps the first rib 21 in plan view. It doesn't have to be.

The member (plate-shaped molded body) to which the present invention is applied has the structure of the plate-shaped molded body 1 described above as a part of the member. As a result, in the member to which the present invention is applied, strain in the portion where the front rib is formed is relieved by the back rib, and warpage of the entire member is suppressed.

Although the preferred embodiments according to the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to such examples. The various shapes, combinations, etc., of the constituent members shown in the above examples are merely examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

EXAMPLES The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples.

In the examples, the warpage of the obtained plate-shaped molding was evaluated by injection molding simulation using a flow analysis model as shown in FIG. Evaluation conditions are as follows.

(Evaluation conditions)
Analysis software: Moldflow Insight 2019 (manufactured by Autodesk)
Resin material: Sumikasuper LCP E6808LHF
Flow analysis conditions: filling + holding pressure + warpage (orientation, shrinkage)
Molding conditions: Table 1 below

(Plate shaped body)
Longitudinal dimension: 300 mm Width dimension: 50 mm (mold set value)
Front rib Height: 1.0mm Width: 1.0mm Spacing: 20mm

First, using a liquid crystal polymer as a material, a molten resin is injected from a gate provided at the end in the longitudinal direction to simulate the injection molding of such a plate-like molded body. was 298.2 mm. As a result, it was reduced by 1.8 mm from the set value of the mold, and it was confirmed that the dimensional accuracy in the longitudinal direction was high.

The model shown in FIG. 5 includes the aforementioned base, a plurality of front ribs provided on the front surface of the base, and a plurality of rear ribs provided on the back of the base. The plurality of front ribs includes ribs corresponding to the first rib and the pair of ribs described above, and the plurality of back ribs includes the second rib described above. The second rib overlaps the first rib in plan view.

(Sample No. 1 to 20)
Simulations were performed by changing the conditions of the ribs of the plate-like moldings to be molded as shown in Tables 2 and 3 below.

In Tables 2 and 3, "-" indicates no data.

In Table 2, "equally spaced and alternately arranged" means that the front ribs and the back ribs are alternately arranged at equal intervals in plan view.
No. Sample No. 19 is arranged with back ribs, front ribs, .
No. Sample No. 20 is arranged in order from the back rib on one end side in the longitudinal direction of the base, with front ribs, back ribs, . Therefore, No. In sample No. 20, the back rib is one more than the front rib.

In Table 3, |AB| corresponds to the angle formed by the first rib and the second rib.

The flatness of each sample was calculated and evaluated as follows.

(Calculation of flatness)
The flatness (unit: mm) was calculated using the height from the reference surface when the plate-shaped molded body was placed on the reference surface on one side of the obtained plate-shaped molded body.

First, on each of both sides of the plate-like compact in the longitudinal direction, the height was determined at a total of 5 points (a total of 10 points on both sides) of 2 points at both ends and 3 points equidistantly between both ends. Next, a least-squares plane was calculated by the least-squares method for the obtained 10 heights, and the height of the obtained least-squares plane from the reference plane was used as the flatness.

It can be judged that deformation (warpage) is small in a plate-shaped compact with small flatness. Table 4 shows the results of the calculated flatness. No. which does not have a back rib. No. 1 sample was used as a reference (reference example). A sample having a flatness smaller than that of sample No. 1 (7.03 mm) was used as Example No. 1 sample. A sample having a flatness greater than that of the sample No. 1 was used as a comparative example. No. Samples 12, 15 and 16 are comparative examples.

No. In samples 2 and 11, the deformation was completely canceled, and neither the front side nor the back side was convex.

No. For samples 2 to 11, 13, 14, and 17 to 20, |xsinA-ysinB| °Meet the following. It was found that warpage was suppressed for these samples.

FIG. FIG. 11 is a scatter diagram showing the correspondence between |xsinA−ysinB| and flatness for 11 to 18 samples. In FIG. 6, the horizontal axis indicates flatness, and the vertical axis indicates |xsinA-ysinB|.

As shown in FIG. 6, it was found that the greater the |xsinA−ysinB|, the greater the flatness and the greater the warp.

From these, it was confirmed that the present invention is useful.

DESCRIPTION OF SYMBOLS 1, 1A, 1X... Plate-shaped compact, 10... Base, 10a... Front surface, 10b... Back surface, 20... Front rib, 21... First rib, 22, 23... Rib (a pair of ribs), 30... Back rib 31...Second rib AR...Range L...Virtual line

Claims (7)

Made of liquid crystal polyester,
a plate-like base;
a plurality of front ribs provided on the front surface of the base;
a plurality of back ribs provided on the back surface of the base,
The base is strip-shaped extending in one direction,
The plurality of front ribs includes a first rib projecting from the front surface and a pair of ribs projecting from the front surface at positions sandwiching the first rib,
The plurality of back ribs includes second ribs protruding from the back surface,
The second rib is located in a range from the center of the first rib and one of the pair of ribs to the center of the first rib and the other of the pair of ribs in plan view, not parallel to the ribs,
The volume of the first rib is 70% or more and 130% or less of the volume of the second rib,
The plurality of front ribs and the plurality of back ribs intersect the direction in which the base extends, and satisfy the following formula (1).
|( _sinA1 +sinA2 ₊ ...+ _sinAx )-( _sinB1 +sinB2 ₊ ...+ _sinBy )|≤1...(1)
(Wherein, x is the number of the front ribs, y is the number of the back ribs, A _x is the angle between the front ribs and an imaginary line perpendicular to the extending direction in plan view, B _y is the imaginary line and the showing the angle with the back rib) 2. The molded plate according to claim 1, wherein an angle formed by said first rib and said second rib is more than 0[deg.] and 4[deg.] or less in plan view. Made of liquid crystal polyester,
a plate-like base;
a plurality of front ribs provided on the front surface of the base;
a plurality of back ribs provided on the back surface of the base,
The plurality of front ribs includes a first rib projecting from the front surface and a pair of ribs projecting from the front surface at positions sandwiching the first rib,
The plurality of back ribs includes second ribs protruding from the back surface,
The second rib is located in a range from the center of the first rib and one of the pair of ribs to the center of the first rib and the other of the pair of ribs in plan view,
The volume of the first rib is 70% or more and 130% or less of the volume of the second rib,
A plate-like formed body, wherein an angle formed by the first rib and the second rib is 0° or more and 4° or less in a plan view. The base is strip-shaped extending in one direction,
4. The molded plate according to claim 3, wherein the plurality of front ribs and the plurality of back ribs are provided so as to cross the extending direction of the base. The plate-shaped compact according to claim 4, which satisfies the following formula (1).
|( _sinA1 +sinA2 ₊ ...+ _sinAx )-( _sinB1 +sinB2 ₊ ...+ _sinBy )|≤1...(1)
(Wherein, x is the number of the front ribs, y is the number of the back ribs, A _x is the angle between the front ribs and an imaginary line perpendicular to the extending direction in plan view, B _y is the imaginary line and the showing the angle with the back rib) 6. The molded plate according to claim 3, wherein said first rib and said second rib are parallel in plan view. The plate-like formed article according to any one of claims 1 to 6, wherein the first rib and the second rib overlap in plan view.

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