阅读说明：本技术 液晶聚酯组合物和树脂成型体 (Liquid crystal polyester composition and resin molded article ) 是由 枌宏充 于 2018-11-14 设计创作，主要内容包括：一种液晶聚酯组合物,其包括液晶聚酯和纤维状填料,在该纤维状填料中,相对于该纤维状填料的根数,纤维状填料中包括的纤维长度为80μm以上的长纤维的根数为30％以下,该纤维状填料的数均纤维直径为12μm以下。(A liquid crystal polyester composition comprising a liquid crystal polyester and a fibrous filler, wherein the fibrous filler contains 30% or less of long fibers having a fiber length of 80 [ mu ] m or more, based on the number of the fibrous filler, and the number-average fiber diameter of the fibrous filler is 12 [ mu ] m or less.)

1. A liquid crystal polyester composition, wherein,

which comprises a liquid crystalline polyester and a fibrous filler,

in the fibrous filler, the number of long fibers having a fiber length of 80 μm or more contained in the fibrous filler is 30% or less relative to the number of the fibrous filler,

the fibrous filler has a number average fiber diameter of 12 μm or less.

2. A liquid crystal polyester composition, wherein,

which comprises a liquid crystalline polyester and a fibrous filler,

the number-average fiber length of the fibrous filler is 15 to 60 [ mu ] m,

the fibrous filler has a number average fiber diameter of 12 μm or less.

3. The liquid-crystalline polyester composition according to claim 1 or 2,

the fibrous filler has a number average fiber diameter of 6 μm or less.

4. A liquid-crystalline polyester composition as claimed in any one of claims 1 to 3,

the content of the fibrous filler is 10 parts by mass or more and 150 parts by mass or less with respect to 100 parts by mass of the liquid crystal polyester.

5. A resin molded body, wherein,

formed from the liquid-crystalline polyester composition according to any one of claims 1 to 4.

Technical Field

The present invention relates to a liquid crystal polyester composition and a resin molded article.

The present application is based on japanese patent application No. 2017-220365, filed in japan on 11/15/2017 and claiming priority, the contents of which are incorporated herein by reference.

Background

In general, liquid crystal polyesters are rarely used as a single substance, and are used as liquid crystal polyester compositions containing a filler in L CP (liquid crystal polyester) in order to satisfy required characteristics (for example, flexural strength) for various applications.

When a molded article such as an electric/electronic component or an optical device component is produced using the liquid crystal polyester composition, foreign matter generated from the molded article may reduce the yield in the assembly process of the electric/electronic component or the optical device component. Further, since the electric/electronic devices and optical devices using the above-described member (molded body) are used for a long period of time, foreign substances generated from the molded body may cause a failure. Therefore, studies have been made on a molded article in which the generation of foreign substances is suppressed.

For example, patent document 1 describes a liquid crystal polyester resin composition capable of preventing the generation of surface particles (foreign matter). The liquid crystal polyester resin composition described in patent document 1 contains 0.01 to 10 parts by weight of activated carbon, 5 to 50 parts by weight of glass fiber, and 1 to 50 parts by weight of flake mica, based on 100 parts by weight of liquid crystal polyester.

Disclosure of Invention

Problems to be solved by the invention

However, the liquid crystal polyester resin composition described in patent document 1 does not necessarily suppress the generation of foreign matter, and further improvement is required.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a liquid crystal polyester composition and a resin molded article in which generation of foreign substances is suppressed.

Means for solving the problems

In order to solve the above problems, one aspect of the present invention provides a liquid crystal polyester composition comprising a liquid crystal polyester and a fibrous filler, wherein the fibrous filler comprises 30% or less of long fibers having a fiber length of 80 μm or more, based on the number of the fibrous filler, and the number average fiber diameter of the fibrous filler is 12 μm or less.

One aspect of the present invention provides a liquid crystal polyester composition comprising a liquid crystal polyester and a fibrous filler, wherein the number average fiber length of the fibrous filler is 15 μm or more and 60 μm or less, and the number average fiber diameter of the fibrous filler is 12 μm or less.

In one aspect of the present invention, the fibrous filler may have a number average fiber diameter of 6 μm or less.

In one aspect of the present invention, the fibrous filler may be contained in an amount of 10 parts by mass or more and 150 parts by mass or less based on 100 parts by mass of the liquid crystal polyester.

In one aspect of the present invention, there is provided a resin molded article comprising the above-mentioned liquid crystal polyester composition as a molding material.

Namely, the present invention includes the following aspects.

[1] A liquid crystal polyester composition comprising a liquid crystal polyester and a fibrous filler, wherein the number of long fibers having a fiber length of 80 [ mu ] m or more contained in the fibrous filler is 30% or less relative to the number of the fibrous filler, and the number-average fiber diameter of the fibrous filler is 12 [ mu ] m or less.

[2] A liquid crystal polyester composition comprising a liquid crystal polyester and a fibrous filler, wherein the fibrous filler has a number average fiber length of 15 μm or more and 60 μm or less and a number average fiber diameter of 12 μm or less.

[3] The liquid-crystalline polyester composition according to [1] or [2], wherein the fibrous filler has a number-average fiber diameter of 6 μm or less.

[4] The liquid-crystalline polyester composition according to any one of [1] to [3], wherein the fibrous filler is contained in an amount of 10 to 150 parts by mass based on 100 parts by mass of the liquid-crystalline polyester.

[5] A resin molded article comprising the liquid crystal polyester composition according to any one of [1] to [4 ].

ADVANTAGEOUS EFFECTS OF INVENTION

According to one aspect of the present invention, there are provided a liquid crystal polyester composition and a resin molded article in which generation of foreign substances is suppressed.

In the present specification, the "foreign matter" refers to a component derived from a liquid crystal polyester composition, which is generated at the time of assembly or use of an electric/electronic device or an optical device having a resin molded article formed from the liquid crystal polyester composition as a component. For example, it means fibrous filler, liquid crystalline polyester resin, and a mixture thereof.

Detailed Description

The liquid crystal polyester composition of the present embodiment is used as a material for forming a resin molded article described later. The liquid crystal polyester composition of the present embodiment includes a liquid crystal polyester and a fibrous filler.

In the present specification, a mixture obtained by mixing a liquid crystal polyester and a fibrous filler is referred to as a "composition". The material obtained by molding the obtained mixture into pellets is also referred to as "composition" in the same manner.

[ liquid-crystalline polyester ]

The liquid crystal polyester of the liquid crystal polyester composition of the present embodiment is a material exhibiting liquid crystallinity in a molten state. The liquid crystal polyester can be liquid crystal polyester amide, liquid crystal polyester ether, liquid crystal polyester carbonate or liquid crystal polyester imide.

The flow initiation temperature of the liquid crystal polyester of the present embodiment is preferably 330 ℃ or higher. The flow starting temperature of the liquid crystal polyester is more preferably 330 ℃ or more and 450 ℃ or less, still more preferably 330 ℃ or more and 400 ℃ or less, and particularly preferably 330 ℃ or more and 390 ℃ or less. The flow initiation temperature may be 340 ℃ or higher, 350 ℃ or higher, or 360 ℃ or higher.

In one aspect, the flow start temperature may be 340 ℃ to 450 ℃, 350 ℃ to 400 ℃, or 360 ℃ to 390 ℃.

The flow initiation temperature was measured at 9.8MPa (100 kg/cm) using a Capillary rheometer (Capillary rheometer)²) The temperature is raised at a rate of 4 ℃/min under the load of (1),meanwhile, the liquid crystal polyester was melted and extruded from a nozzle having an inner diameter of 1mm and a length of 10mm, and the temperature at which the viscosity of 4800 pas (48000 poise) was exhibited became a reference for the molecular weight of the liquid crystal polyester (see "synthesis, molding, and application of liquid crystal polymer" (liquid crystal ポリマー -synthesis, molding, and application-), CMC co., ltd. シーエムシー, 6/5/1987, p.95).

The liquid crystal polyester of the present embodiment is preferably a wholly aromatic liquid crystal polyester obtained by polymerizing only an aromatic compound as a raw material monomer.

Typical examples of the liquid crystal polyester of the present embodiment include a liquid crystal polyester obtained by polymerizing (polycondensing) at least one compound selected from the group consisting of an aromatic diol, an aromatic hydroxylamine and an aromatic diamine, an aromatic hydroxycarboxylic acid and an aromatic dicarboxylic acid; a liquid crystal polyester obtained by polymerizing a plurality of aromatic hydroxycarboxylic acids; a liquid crystal polyester obtained by polymerizing at least one compound selected from the group consisting of aromatic hydroxylamine and aromatic diamine, aromatic dicarboxylic acid, and aromatic diol; and a liquid crystal polyester obtained by polymerizing a polyester such as polyethylene terephthalate and an aromatic hydroxycarboxylic acid.

In this case, a polymerizable derivative of an aromatic hydroxycarboxylic acid, an aromatic dicarboxylic acid, an aromatic diol, an aromatic hydroxylamine, and an aromatic diamine may be used in place of a part or all of them.

Examples of polymerizable derivatives of compounds having a carboxyl group such as aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids include those obtained by converting a carboxyl group into an alkoxycarbonyl group or an aryloxycarbonyl group (i.e., esters), those obtained by converting a carboxyl group into a haloformyl group (i.e., acid halides), and those obtained by converting a carboxyl group into an acyloxycarbonyl group (i.e., acid anhydrides).

Examples of polymerizable derivatives of compounds having a hydroxyl group such as aromatic hydroxycarboxylic acids, aromatic diols, and aromatic hydroxylamines include compounds obtained by acylating a hydroxyl group and replacing the hydroxyl group with an acyloxy group (i.e., an acylate of a hydroxyl group).

Examples of polymerizable derivatives of compounds having an amino group such as aromatic hydroxylamine and aromatic diamine include compounds obtained by acylating an amino group and replacing it with an amido group (i.e., acylates of an amino group).

The liquid crystal polyester of the present embodiment preferably has a repeating unit represented by the following formula (1) (hereinafter, may be referred to as "repeating unit (1)"), more preferably has a repeating unit (1), a repeating unit represented by the following formula (2) (hereinafter, may be referred to as "repeating unit (2)"), and a repeating unit represented by the following formula (3) (hereinafter, may be referred to as "repeating unit (3)").

(1)-O-Ar¹-CO-

(2)-CO-Ar²-CO-

(3)-X-Ar³-Y-

In the above formulae (1) to (3), Ar¹Represents phenylene, naphthylene or biphenylene. Ar (Ar)²And Ar³Each independently represents a phenylene group, a naphthylene group, a biphenylene group or a group represented by the following formula (4). X and Y each independently represent an oxygen atom or an imino group (-NH-). From Ar¹、Ar²Or Ar³The hydrogen atoms in the groups represented by (a) may each be independently substituted with a halogen atom, an alkyl group or an aryl group.

(4)-Ar⁴-Z-Ar⁵-

In formula (4), Ar⁴And Ar⁵Each independently represents a phenylene group or a naphthylene group. Z represents an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group or an alkylene group.

From Ar⁴Or Ar⁵The hydrogen atoms contained in the groups represented may be substituted independently of each other by halogen atoms, alkyl groups or aryl groups.

Examples of the halogen atom which may be substituted for a hydrogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

The alkyl group which may be substituted for a hydrogen atom is preferably an alkyl group having 1 to 10 carbon atoms, and examples thereof include a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a n-hexyl group, a 2-ethylhexyl group, a n-octyl group and a n-decyl group.

As the above-mentioned aryl group which can be substituted for a hydrogen atom, at least one of the hydrogen atoms constituting the aryl group may be substituted, and an aryl group having 6 to 20 total carbon atoms containing the substituent is preferable, and examples thereof include a phenyl group, an o-tolyl group, an m-tolyl group, a p-tolyl group, a 1-naphthyl group and a 2-naphthyl group.

When is caused by Ar¹、Ar²Or Ar³When the hydrogen atom in the group represented by (A) is substituted by these groups, the number of substitution is each Ar¹、Ar²Or Ar³The above groups are each independently usually 2 or less, preferably 1.

The alkylene group is preferably an alkylene group having 1 to 10 carbon atoms, and examples thereof include a methylene group, an ethylene group, an isopropylene group, an n-butylene group and a 2-ethylhexylene group.

The repeating unit (1) is a repeating unit derived from a predetermined aromatic hydroxycarboxylic acid. As the repeating unit (1), Ar is preferred¹Repeating units that are p-phenylene (e.g., repeating units from p-hydroxybenzoic acid), and Ar¹Is a repeating unit of 2, 6-naphthylene (e.g., a repeating unit from 6-hydroxy-2-naphthoic acid).

In the present specification, "derived" means that a chemical structure is changed by polymerization of a raw material monomer, and that no other structural change is caused.

The repeating unit (2) is a repeating unit derived from a predetermined aromatic dicarboxylic acid. As the repeating unit (2), Ar is preferred²Repeating units that are p-phenylene (e.g., repeating units from terephthalic acid), Ar²Repeating units that are m-phenylene (e.g., repeating units from isophthalic acid), Ar²Repeating units that are 2, 6-naphthylene (e.g., repeating units derived from 2, 6-naphthalenedicarboxylic acid), and Ar²A repeating unit that is diphenyl ether-4, 4 '-diyl (e.g., a repeating unit derived from diphenyl ether-4, 4' -dicarboxylic acid).

The repeating unit (3) is a repeating unit derived from a predetermined aromatic diol, aromatic hydroxylamine or aromatic diamine.As the repeating unit (3), Ar is preferred³Repeating units that are p-phenylene (e.g., repeating units from hydroquinone, p-aminophenol, or p-phenylenediamine), and Ar³Is a repeating unit of 4, 4 '-biphenylene (e.g., a repeating unit derived from 4, 4' -dihydroxybiphenyl, 4-amino-4 '-hydroxybiphenyl, or 4, 4' -diaminobiphenyl).

The content of the repeating unit (1) in the liquid crystal polyester is usually 30 mol% or more, preferably 30 to 80 mol%, more preferably 40 to 70 mol%, and further preferably 45 to 65 mol% based on the total amount of all repeating units constituting the liquid crystal polyester.

The total amount of all the repeating units constituting the liquid crystal polyester is a value obtained by dividing the mass of each repeating unit constituting the liquid crystal polyester by the formula weight of each repeating unit to obtain a material mass equivalent (mol) of each repeating unit and summing them. The mass of each repeating unit constituting the liquid crystal polyester is calculated from the amount of the raw material monomer used, and is a numerical value assuming that all the raw material monomers are reacted.

Similarly, the content of the repeating unit (2) in the liquid crystal polyester is usually 35 mol% or less, preferably 10 to 35 mol%, more preferably 15 to 30 mol%, and still more preferably 17.5 to 27.5 mol% based on the total amount of all repeating units constituting the liquid crystal polyester.

The content of the repeating unit (3) in the liquid crystal polyester is usually 35 mol% or less, preferably 10 to 35 mol%, more preferably 15 to 30 mol%, and further preferably 17.5 to 27.5 mol% based on the total amount of all repeating units constituting the liquid crystal polyester.

The higher the content of the repeating unit (1), the more easily the melt flowability, heat resistance, strength and rigidity of the liquid crystal polyester are improved. However, if the content of the repeating unit (1) is more than 80 mol%, the melting temperature and the melt viscosity tend to increase, and the temperature required for molding tends to increase.

In the liquid-crystalline polyester of the present embodiment, the ratio of the content of the repeating unit (2) to the content of the repeating unit (3) is calculated from the formula represented by [ content of the repeating unit (2) ]/[ content of the repeating unit (3) ] (mol%/mol%). The ratio of the content of the repeating unit (2) to the content of the repeating unit (3) is usually 0.9 to 1.11, preferably 0.95 to 1.05, and more preferably 0.98 to 1.02.

The repeating units (1) to (3) of the liquid crystal polyester may be derived independently from one raw material monomer or may be derived from two or more raw material monomers. The liquid crystal polyester may have a repeating unit other than the repeating units (1) to (3). The content of the repeating unit other than the repeating units (1) to (3) is usually 0 mol% or more and 10 mol% or less, and preferably 0 mol% or more and 5 mol% or less, based on the total amount of all the repeating units constituting the liquid crystal polyester.

It is preferable that the liquid-crystalline polyester has the repeating unit (3) in which X and Y are each an oxygen atom. That is, since the melt viscosity tends to be low, it is preferable to have a repeating unit derived from a predetermined aromatic diol. Further, the repeating unit (3) having only X and Y each as an oxygen atom is more preferable.

The liquid crystal polyester of the method for producing a liquid crystal polyester composition of the present embodiment may be commercially available, or may be synthesized from raw material monomers corresponding to the repeating units constituting the liquid crystal polyester.

When synthesizing a liquid crystal polyester, it is preferably produced by melt-polymerizing raw material monomers and solid-phase polymerizing the resulting polymer (hereinafter, sometimes referred to as "prepolymer"). Thus, for example, a liquid crystal polyester having a high flow initiation temperature of 330 ℃ or higher can be produced with good workability.

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

The liquid crystal polyester is a liquid crystal polyester having the same repeating unit in the above-mentioned range, and liquid crystal polyesters having different repeating unit contents may be used in combination.

[ fibrous Filler ]

As a material constituting the fibrous filler of the present embodiment, an inorganic material is preferable from the viewpoint of obtaining a resin molded product with higher strength. Specific examples of the fibrous filler of the present embodiment include glass fibers, ceramic fibers, PAN-based carbon fibers, pitch-based carbon fibers, alumina fibers, silica fibers, and silica-alumina fibers. Among these, glass fibers are more preferable as the fibrous filler in terms of a small abrasion load applied to the apparatus at the time of molding and easy acquisition. The fibrous filler of the present embodiment does not include a whisker filler. In general, whiskers refer to thin, whisker-like single crystal fibers capable of crystal growth.

The liquid crystal polyester composition of the present embodiment has a number average fiber diameter of the fibrous filler of 12 μm or less and a number average fiber length of the fibrous filler of 15 μm to 60 μm. By satisfying these conditions, the resin molded article molded from the liquid crystal polyester composition of the present embodiment can suppress the generation of foreign substances at the time of assembly or use.

In one aspect, the fibrous filler may have a number average fiber length of 26 μm or more and 59 μm or less.

In addition, in order to further suppress the generation of foreign matter at the time of assembly or use, the number average fiber diameter of the fibrous filler is preferably 11 μm or less. The number average fiber diameter of the fibrous filler is more preferably 6 μm or less, and still more preferably 5 μm or less. If the number average fiber diameter of the fibrous filler is 5 μm or less, the strength of the resin molded article is improved, although the reason is not clear. The lower limit of the number average fiber diameter of the fibrous filler is not limited, and is 2 μm or more in actual practice for the convenience of melt kneading in the production of the liquid crystal polyester composition.

In one aspect, the fibrous filler has a number average fiber diameter of 2 to 12 μm, preferably 2 to 11 μm, more preferably 2 to 6 μm, and still more preferably 2 to 5 μm.

In the liquid crystal polyester composition of the present embodiment, the fibrous filler contains long fibers having a fiber length of 80 μm or more in an amount of 0% to 30% relative to the number of fibrous fillers. If the content of the long fibers in the liquid crystal polyester composition of the present embodiment is 0% or more and 30% or less, a resin molded article in which generation of foreign matter is suppressed can be molded.

In order to obtain a resin molded article in which the generation of foreign matter is further suppressed during assembly or use, the content of the long fibers is preferably 0% to 25% relative to the number of fibrous fillers. On the other hand, the content of the long fibers may be 0% to 22%, or 1% to 11%, relative to the number of fibrous fillers.

In the present specification, the number average fiber diameter and the number average fiber length of the fibrous filler in the liquid crystal polyester composition and the ratio (content ratio) of the long fiber to the number of the fibrous filler can be determined from a photomicrograph of the fibrous filler contained in the liquid crystal polyester composition.

Specifically, these measurement methods will be explained. In the following measurement method, the number of observation pieces (the number of fibrous fillers) in a photomicrograph is 400.

First, the liquid crystal polyester composition is ashed under a condition of 600 ℃ or higher. Then, the obtained residue was dispersed in methanol, and a photomicrograph was taken at a magnification of 100 times in a state of being spread on a glass slide. Then, the length (fiber length) of the fibrous filler is read from the obtained photograph, and the number-average fiber length of the fibrous filler can be determined by calculating the average value of the number (400) of the fibrous fillers.

The number-average fiber diameter of the fibrous filler can be determined by taking a photomicrograph at a magnification of 500 times, reading the fiber diameter of the fibrous filler from the obtained photomicrograph, and calculating the average value of the number (400) of the fibrous filler.

The content of the long fibers having a fiber length of 80 μm or more can be calculated by dividing the number of the long fibers having a fiber length of 80 μm or more by the number of the fibrous fillers (400), using the measured value of the fiber length obtained by the above measurement.

The term "fiber length" means the maximum length of the fibrous filler.

The "fiber diameter" means, for example, the maximum diameter (length) in the direction orthogonal to the longitudinal direction of the fibrous filler.

The upper limit of the length of the long fibers contained in the fibrous filler is usually 1000 μm or less.

Further, the fibrous filler of the present embodiment is preferably not subjected to surface coating treatment. This prevents the generation of gas from the surface coating agent adhering to the fibrous filler of the obtained resin molded article, and thus can improve the chemical stability of the resin molded article. Further, when the resin molded body is assembled, it is difficult for the peripheral members to be contaminated with the generated gas from the resin molded body. In the present embodiment, examples of the surface coating treatment include a surface coating treatment using a coupling agent such as a silane coupling agent or a titanium coupling agent, and a surface coating treatment using a thermoplastic resin or a thermosetting resin other than a liquid crystal polyester.

Preferably, the liquid crystal polyester composition of the present embodiment includes 10 parts by mass or more and 150 parts by mass or less of the fibrous filler with respect to 100 parts by mass of the liquid crystal polyester. If the fibrous filler is more than 150 parts by mass, foreign matter tends to be easily generated in the resin molded article obtained at the time of assembly or use. On the other hand, if the fibrous filler is less than 10 parts by mass, the dimensional stability of the obtained resin molded article tends to be lowered, and it tends to be difficult to obtain a resin molded article of a desired size. If the fibrous filler is less than 10 parts by mass, the anisotropy of the liquid crystal polyester is strongly developed, and the resin molded article may be warped. Further, if the fibrous filler is small, the effect of improving the mechanical strength may be reduced.

In consideration of the balance among the properties such as generation of foreign matter, dimensional stability, warpage, and mechanical strength of the resin molded article, the content of the fibrous filler in the liquid crystal polyester composition of the present embodiment is more preferably 15 parts by mass or more, still more preferably 20 parts by mass or more, particularly preferably 25 parts by mass or more, and particularly preferably 30 parts by mass or more, per 100 parts by mass of the liquid crystal polyester. The content of the fibrous filler in the liquid crystal polyester composition of the present embodiment is more preferably 140 parts by mass or less, and still more preferably 70 parts by mass or less, based on 100 parts by mass of the liquid crystal polyester.

In one aspect, the content of the fibrous filler in the liquid crystal polyester composition of the present embodiment is more preferably 15 parts by mass or more and 140 parts by mass or less, still more preferably 20 parts by mass or more and 70 parts by mass or less, particularly preferably 25 parts by mass or more and 70 parts by mass or less, and particularly preferably 30 parts by mass or more and 70 parts by mass or less, with respect to 100 parts by mass of the liquid crystal polyester.

In one aspect, the content of the liquid crystal polyester in the liquid crystal polyester composition of the present embodiment is preferably 42 to 87% by mass based on the total mass of the liquid crystal polyester composition.

In one aspect, the content of the fibrous filler in the liquid crystal polyester composition of the present embodiment is preferably 13 to 58% by mass based on the total mass of the liquid crystal polyester composition.

Other components (additives and the like) may be included in the liquid crystal polyester composition of the present embodiment within a range not to impair the effects of the present invention. Examples of such additives include plate-like fillers, coloring components, lubricants, and stabilizers.

In one aspect, the content of the other component is preferably 0.0001 to 5 parts by mass with respect to 100 parts by mass of the liquid crystal polyester.

In another aspect, the content of other components in the liquid crystal polyester composition of the present embodiment is preferably 0.01 to 5% by mass based on the total mass of the liquid crystal polyester composition.

< method for producing liquid-crystalline polyester composition >

In order to obtain the resin molded article of the present embodiment, it is preferable to produce a liquid crystal polyester composition in the form of pellets (hereinafter, sometimes referred to as "composition") by previously melt-kneading a liquid crystal polyester and a fibrous filler. When additives other than the liquid crystal polyester and the fibrous filler are used, the liquid crystal polyester and the fibrous filler may be melt-kneaded together with the additives to form a composition.

< resin molded article >

The resin molded article of the present embodiment uses the liquid crystal polyester composition as a material for forming the resin molded article. According to the resin molded body of the present embodiment, generation of foreign matter can be suppressed when the resin molded body is assembled or used (that is, when an electric/electronic apparatus or an optical apparatus having the resin molded body as a component is assembled or used). The effect of suppressing the generation of such foreign matter can be confirmed by the following test.

First, after the composition was dried, injection molding was performed using an injection molding machine (PS 40E-5ASE model manufactured by Nichisu resin industries Co., Ltd.) under molding conditions of a cylinder temperature of 350 ℃, a mold temperature of 130 ℃ and an injection speed of 60% to obtain a test piece (resin molded article) having a length of 64mm, a width of 64mm and a thickness of 1mm, and a film gate of 64mm × 1mm was provided at an end edge of a cavity of the mold for injection molding.

On the upper surface portion of the test piece, an adhesive tape (Sellotap (registered trademark) No. 405, manufactured by Mitsubishi corporation, Inc. (ニチバン Co., Ltd.) was applied over the entire length of the test piece along the flow direction of the liquid crystal polyester in the test piece, and the peeling operation was rapidly performed from one end side to the other end side of the adhesive tape along the flow direction. This operation was repeated a total of 20 times as one operation, and a tape peeling test was performed.

Then, the surface roughness Sa of the test piece was measured at the site where the test was performed using a 3D shape measuring instrument ("VR 3000") manufactured by keyence corporation (キーエンス).

The surface roughness Sa of the resin molded body of the present embodiment is preferably 0 μm or more and 0.55 μm or less, and more preferably 0.50 μm or less. If the surface roughness Sa of the resin molded article of the present embodiment is 0.55 μm or less, the generation of foreign matter can be suppressed during assembly or production of the resin molded article.

In the above test, the removal of the fibrous filler was promoted by repeating tape peeling of the resin molded body to roughen the surface of the resin molded body. That is, the tape peeling test can be considered as an accelerated test of the generation of foreign matter from the resin molded body.

In particular, when the number average fiber diameter of the fibrous filler of the present embodiment is 2 μm or more and 6 μm or less, the izod impact strength of the resin molded product can be improved.

In the present specification, the izod impact strength of the resin molded product was measured as follows. First, the composition was dried and then injection-molded using an injection molding machine (PS 40E-5ASE model manufactured by Nichisu resin industries Co., Ltd.) under molding conditions of a cylinder temperature of 350 ℃, a mold temperature of 130 ℃ and an injection speed of 60%, to obtain a test piece having a length of 64mm, a width of 12.7mm and a thickness of 6.4 mm.

Then, the resulting test piece was measured for the Izod impact strength according to ASTM D256.

< method for producing resin molded article >

The composition obtained by the above method is injection molded to obtain a resin molded article.

First, the flow initiation temperature FT (. degree. C.) of the composition used was determined. In order to suppress the generation of foreign matter in the resin molded article, a preferable injection molding method includes a method of melting the composition under a temperature condition of [ FT +30] deg.c or more and [ FT +80] deg.c or less with respect to a flow start temperature FT (° c) of the composition, and performing injection molding in a mold set to a temperature of 80 ℃ or more. It is preferable that the composition is dried in advance before injection molding.

When the composition is injection-molded under a temperature condition that the resin melting temperature is [ FT +30 ]. degree.C. or higher, the surface strength of the obtained resin molded article tends to be improved, and the generation of foreign matter tends to be suppressed. Further, if the above composition is injection molded under a temperature condition that the resin melting temperature is [ FT +30 ]. degree.C. or higher, the fluidity of the resin is improved when the composition is molded.

On the other hand, if injection molding is performed under a temperature condition where the resin melting temperature is [ FT +80 ]. degree.C.or lower, the liquid crystal polyester remaining inside the molding machine is less likely to be decomposed. As a result, the obtained resin molded article is less likely to generate gas and the like, and can be applied to applications such as electric/electronic components and optical components. Further, if injection molding is performed under a temperature condition where the resin melting temperature is [ FT +80] ° c or lower, the molten resin is less likely to flow out from the nozzle when the mold is opened to take out the resin molded article after injection molding. As a result, there is no need to cope with the outflow of the molten resin, and the productivity of the resin molded article is improved.

Since the resin molded body can be molded stably, injection molding is more preferably performed under a temperature condition in which the resin melting temperature is [ FT +30] DEG C or higher and [ FT +60] DEG C or lower.

On the other hand, the mold temperature used is preferably 80 ℃ or higher. When the mold temperature is 80 ℃ or higher, the surface of the obtained resin molded article becomes smooth, and the amount of foreign matter generated tends to be suppressed.

In addition, from the viewpoint of reducing the amount of foreign matter generated, it is advantageous to use a mold having a higher temperature, but if it is too high, the cooling effect is reduced and the time required for the cooling step is prolonged. As a result, there may be a problem that productivity of the resin molded article is lowered, or it is difficult to release the resin molded article after molding, and the resin molded article is deformed. Further, if the temperature of the mold used is too high, the engagement between the molds is deteriorated, and the resin molded body may be damaged when the mold is opened or closed.

Therefore, it is preferable to appropriately optimize the upper limit of the mold temperature to be used, depending on the kind of the composition to be used. This can suppress decomposition of the liquid crystal polyester contained in the composition.

As described above, when the liquid crystal polyester used in the production method of the present embodiment is a particularly preferable wholly aromatic liquid crystal polyester as the liquid crystal polyester, the mold temperature to be used is preferably 100 ℃ or higher and 220 ℃ or lower, and more preferably 130 ℃ or higher and 200 ℃ or lower.

In order to determine more practical injection molding conditions of the above composition, various preliminary experiments are preferably performed while changing the molding conditions. Specifically, a preliminary experiment of the following series of operations was performed: the test piece used in the tape peeling test was used as a standard molded body, a tape peeling test was performed, the surface roughness Sa of the standard molded body after the test was obtained, and the injection molding conditions were optimized as follows.

For example, first, the composition is melted and injection-molded in a mold set at 80 ℃ to prepare a standard molded body. In this case, the resin melting temperature is set to a range of [ FT +40] to [ FT +50] DEG C, which is a substantially central value of the resin melting temperature preferably relative to a flow start temperature FT (. degree.C.) determined in advance. Then, the obtained standard molded body was subjected to a tape peeling test to determine the surface roughness Sa of the standard molded body after the test. Then, the mold temperature was gradually increased to mold each standard molded body, and the surface roughness Sa of the standard molded body after the test was similarly determined. Further, if the surface roughness Sa of the standard molded body after the test is similarly determined by sequentially lowering the resin melting temperature, the mold temperature and the resin melting temperature can be optimized separately.

Further, if the tape peeling test and the measurement of mechanical strength such as weld strength are performed on the obtained standard molded article, more preferable injection molding conditions of the composition can be obtained.

The injection rate of the composition may be set to each of the preferable ranges by the molding machine used, and is preferably 50 mm/sec or more. Since the productivity of the resin molded article can be improved, the injection speed of the composition is preferably higher, more preferably 100 mm/sec or more, and still more preferably 200 mm/sec or more.

As described above, the composition is molded by optimizing the injection molding conditions through preliminary experiments for molding the standard molded body, and changing the mold capable of obtaining the standard molded body to the mold capable of obtaining the target resin molded body. By doing so, a resin molded body capable of further suppressing the generation of foreign matter can be obtained.

The resin molded article of the present embodiment can be preferably used for, for example, components for electric/electronic devices or optical devices.

In the injection molding, an example of performing a preliminary experiment using a standard molded body is described, and it is needless to say that the molding conditions can be optimized by a means of performing a tape peeling test on a resin molded body of a target shape and obtaining the surface roughness Sa of the resin molded body after the test.

< use of resin molded article >

Specific examples of the member to which the resin molded body of the present embodiment can be preferably applied include electrical/electronic components such as a connector, a socket, a relay component, a bobbin, an optical pickup, a vibrator, a printed wiring board, a circuit board, a semiconductor package, and a computer-related component; semiconductor manufacturing process-related components such as IC trays and wafer carriers; VTRs, televisions, irons, air conditioners, stereos, dust collectors, refrigerators, electric cookers, lighting fixtures, and other household electronic product components; lighting fixture parts such as lamp reflectors and lamp sockets; audio product parts such as an optical disk, a laser disk (registered trademark), or a speaker; optical cable ferrules, telephone parts, facsimile parts, modems and other communication equipment parts; copier/printer related parts such as a separation claw and a heater base; mechanical parts such as an impeller, a fan gear, a bearing, a motor part, and a housing; automobile parts such as automobile mechanism parts, engine room interior parts, electric power parts, and interior parts; cooking devices such as a microwave cooking pot and a heat-resistant cooker; materials for heat and sound insulation such as floor materials and wall materials; building materials such as support materials (beams, columns, etc.) or roofing materials; radiation facility members such as airplanes, spacecraft, parts for space equipment, and atomic furnaces; a marine facility component; a jig for washing; an optical device component; valves; a tube; nozzles; a filter class; a medical device member; a medical material; a sensor-like component; a sanitary device; sporting goods; a leisure article.

As described above, the resin molded body of the present embodiment can be used for various applications, and the amount of foreign matter generated during assembly or use of the resin molded body of the present embodiment is extremely small, and therefore, when the resin molded body of the present embodiment is used for these applications, the reliability of the resin molded body is improved, and specifically, the resin molded body of the present embodiment is useful for various sensors such as switches, relays, and image sensors, a light emitting diode (also referred to as L ED), and an optical mechanism system.

In one aspect, the liquid crystal polyester composition of the present embodiment includes a liquid crystal polyester and a fibrous filler.

The liquid crystal polyester is a liquid crystal polyester having a repeating unit derived from p-hydroxybenzoic acid, a repeating unit derived from terephthalic acid and a repeating unit derived from isophthalic acid, or a liquid crystal polyester having a repeating unit derived from 6-hydroxy-2-naphthoic acid, a repeating unit derived from 2, 6-naphthalenedicarboxylic acid, a repeating unit derived from terephthalic acid and a repeating unit derived from hydroquinone.

The fibrous filler is at least one selected from the group consisting of ceramic fibers and glass fibers, and the ceramic fibers are preferably alkaline earth silicate fibers.

The fibrous filler has a number average fiber length of 15 to 60 μm, preferably 26 to 59 μm.

The fibrous filler has a number average fiber diameter of 2 to 12 μm, preferably 2 to 11 μm, more preferably 2 to 6 μm, and particularly preferably 2 to 5 μm.

The content of the long fibers having a fiber length of 80 μm or more is 0% to 30%, preferably 0% to 25%, more preferably 0% to 22%, and still more preferably 1% to 11% with respect to the number of the fibrous fillers.

Further, when a test piece is prepared from the liquid crystal polyester composition under the conditions described in the examples below and the Izod impact strength is measured, the Izod impact strength of the test piece is 250J/m or more and 1030J/m or less, preferably 700J/m or more and 1030J/m or less.

When a test piece is prepared under the conditions described in the examples below and the surface roughness Sa after the tape peeling test is measured, the surface roughness Sa of the test piece is 0.55 μm or less, preferably 0.50 μm or less.