JP2016166276A - Hollow molding of polyamide resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hollow molding of a polyamide resin which has sufficient mechanical properties, and is excellent in surface appearance and inside smoothness of the molding.SOLUTION: The hollow molding of a polyamide resin is provided that is a hollow molding of a polyamide resin composed of a polyamide resin composition containing: 25 mass% or more and 85 mass% or less of a polyamide resin (A); and 15 mass% or more and 75 mass% or less of a glass fiber (B). A ratio (X/Y) between a weight average fiber length X (μm) and a median D50 (Y) (μm) of the glass fiber (B) in the hollow molding of the polyamide resin is 1.6 or more.SELECTED DRAWING: None

Description

  The present invention relates to a polyamide resin hollow molded body.

  Polyamide resins are widely used in parts such as automobiles and electrical / electronic products because they are excellent in mechanical properties, thermal properties, and oil resistance. In particular, a reinforced polyamide resin in which glass fibers are blended with a polyamide resin greatly improves mechanical properties, heat resistance, chemical resistance, etc., so parts that have been conventionally made of metal from the viewpoints of weight reduction and process rationalization. Can be made of reinforced polyamide resin, and is suitably used for automobile parts and the like. These parts are desired to have a good appearance from the viewpoint of design and reliability in order to satisfy customer requirements.

  However, in glass fiber reinforced polyamide, glass fibers are likely to be exposed on the surface of the molded body, and this particularly occurs on the surface of a large part or the surface and the inner surface of a molded body having a hollow portion. For this reason, various methods have been proposed so far in order to improve the mechanical properties and the appearance of the molded body.

  For example, for the purpose of simultaneously improving the strength / rigidity and molded appearance of the molded product, polyamide resin and glass fiber are blended within a specific range, and the average length of glass fiber in the resin composition and the standard deviation of fiber length are set. A polyamide resin composition controlled to be in a specific range has been proposed (see, for example, Patent Document 1).

  In addition, for the purpose of improving the inner surface smoothness of a molded article having a hollow portion, a resin composition in which the ratio of glass fibers having a relatively long fiber length of 0.5 mm or more is proposed in the glass fiber in the resin composition is proposed. (For example, refer to Patent Document 2).

JP-A 63-156856 Japanese Patent No. 3683080

  However, in the techniques described in Patent Documents 1 and 2, a molded body that satisfies the surface appearance and the inner surface smoothness of the molded body while ensuring the mechanical strength that is highly demanded when the polyamide resin is applied to automobile parts and the like. Can't get.

  This invention is made | formed in view of the said subject, and it aims at providing the polyamide resin hollow molded object which is excellent in the surface external appearance and inner surface smoothness of a molded object while having sufficient mechanical property.

As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by using a polyamide resin composition having a specific composition, and have completed the present invention.
That is, the present invention is as follows.
[1]
25% by mass or more and 85% by mass or less (A) polyamide resin, 15% by mass or more and 75% by mass or less (B) glass fiber,
A polyamide resin hollow molded body comprising a polyamide resin composition comprising:
The ratio (X / Y) of the weight average fiber length X (μm) and the median value D50 (Y) (μm) of the (B) glass fiber in the polyamide resin hollow molded body is 1.6 or more.
Polyamide resin hollow molded body.
[2]
The component (A) is a polyamide 6, polyamide 66, polyamide 46, polyamide 11, polyamide 12, polyamide 610, polyamide 612, polyamide MXD6, polyamide 6T, polyamide 6I and a copolymer containing at least one of them as a constituent component The polyamide resin hollow molded article according to [1], which is one or more selected from the group consisting of:
[3]
The polyamide resin hollow molded body according to [1] or [2], wherein the weight average fiber length of the component (B) in the polyamide resin hollow molded body is 100 μm or more and 500 μm or less.
[4]
The ratio (Z / Y) of the number average fiber length Z (μm) of the component (B) and the median value D50 (Y) (μm) in the polyamide resin hollow molded body is 1.2 or more, [1 ] The polyamide resin hollow molded body according to any one of [3] to [3].
[5]
The component (B) is a mixture of chopped strands having a number average fiber length of 1.5 mm or more and 9 mm or less and milled fibers having a number average fiber length of 1 mm or less, according to any one of [1] to [4]. Polyamide resin hollow molded body.
[6]
The polyamide resin hollow molded body according to [5], wherein a ratio of the chopped strands to 100% by mass of the component (B) exceeds 50% by mass.

  According to the present invention, a polyamide resin hollow molded body having sufficient mechanical properties and excellent in the surface appearance and inner surface smoothness of the molded body can be obtained.

  Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail. The following embodiment is an exemplification of the present invention, and the present invention is not limited to the following contents. And this invention can be deform | transformed suitably and implemented within the range of the summary.

  The polyamide resin hollow molded body of the present embodiment is from a polyamide resin composition containing (A) a polyamide resin of 25% by mass or more and 85% by mass or less and (B) a glass fiber of 15% by mass or more and 75% by mass or less. This is a polyamide resin hollow molded body. Furthermore, the ratio (X / Y) of the weight average fiber length X (μm) of the (B) glass fiber and the median value D50 (Y) (μm) in the polyamide resin hollow molded body of the present embodiment is 1.6 or more. It is. Since it has such a configuration, the polyamide resin hollow molded body of the present embodiment has sufficient mechanical properties and is excellent in the surface appearance and inner surface smoothness of the molded body.

[Polyamide resin composition]
The polyamide resin composition in this embodiment contains (A) polyamide resin of 25 mass% or more and 85 mass% or less, and (B) glass fiber of 15 mass% or more and 75 mass% or less. Furthermore, in the polyamide resin composition of the present embodiment, the ratio (X / Y) of the weight average fiber length X (μm) and the median value D ₅₀ (Y) (μm) of the glass fiber in the polyamide resin composition is 1. .6 or more. Since it is configured in this manner, the polyamide resin composition in the present embodiment not only exhibits sufficient mechanical properties, but also has an excellent appearance of the molded body, and smoothness of the inner surface when a hollow part molded body is obtained. Even better.

  In addition, the compounding quantity of (A) polyamide resin in the polyamide resin composition in this embodiment is 25 mass% or more from a viewpoint of an external appearance, and is 85 mass% or less from a viewpoint of intensity | strength and rigidity. From the above viewpoints, 40 mass% or more and 75 mass% or less are preferable, More preferably, it is 60 mass% or more and 75% or less.

  In addition, the blending amount of the (B) glass fiber in the polyamide resin composition in the present embodiment is 15% by mass or more from the viewpoint of ensuring excellent strength and rigidity, and the fluidity and the surface of the molded body at the time of injection molding. From the viewpoint of appearance, it is 75% by mass or less. From the above viewpoints, 25 mass% or more and 60 mass% or less are preferable, More preferably, they are 25 mass% or more and 40% or less.

<(A) component>
The (A) polyamide resin in the present embodiment is not particularly limited as long as it has an amide bond {—NH—C (═O) —} in the repeating structure of the polymer.

  The component (A) is not particularly limited as described above. For example, polyamide obtained by ring-opening polymerization of lactams, polyamide obtained by condensing diamine and dicarboxylic acid, aminocarboxylic acid And polyamides obtained by self-condensation. The polymerization method of the polyamide resin is not particularly limited, and for example, melt polymerization, interfacial polymerization, solution polymerization, bulk polymerization, solid phase polymerization, a combination of these, and the like can be used. Moreover, what polymerized the said compound which can be used for a polycondensation to the stage of a low molecular weight oligomer in a polymerization reactor, and made high molecular weight with an extruder etc. can also be used.

  In the present embodiment, the lactams are not particularly limited, and examples thereof include ε-caprolactam, enantolactam, and ω-laurolactam.

  In the present embodiment, the diamine is not particularly limited. For example, aliphatic diamine, alicyclic diamine, and aromatic diamine can be applied. More specifically, for example, tetramethylene diamine, hexamethylene diamine, undecamethylene diamine, dodecamethylene diamine, tridecamethylene diamine, 1,9-nonamethylene diamine, 2-methyl-1,8-octamethylene diamine, 2 2,4-trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, 5-methylnonamethylenediamine, 1,3-bisaminomethylcyclohexane, 1,4-bisaminomethylcyclohexane, m-phenylenediamine , P-phenylenediamine, m-xylylenediamine, p-xylylenediamine and the like.

  In the present embodiment, the dicarboxylic acid is not particularly limited. For example, aliphatic dicarboxylic acid, alicyclic dicarboxylic acid, and aromatic dicarboxylic acid can be applied. More specifically, for example, adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, 1,1,3-tridecanedioic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, terephthalate Acid, isophthalic acid, naphthalenedicarboxylic acid, dimer acid and the like can be mentioned.

  In this embodiment, the aminocarboxylic acid is not particularly limited. For example, ε-aminocaproic acid, 7-aminoheptanoic acid, 8-aminooctanoic acid, 9-aminononanoic acid, 11-aminoundecanoic acid, 12-aminododecane. Examples include acid and 13-aminotridecanoic acid.

  The polyamide is not particularly limited. For example, a copolymer polyamide obtained by polycondensation of lactams, diamine, dicarboxylic acid and / or ω-aminocarboxylic acid alone or in a mixture of two or more thereof. Can also be used.

  Furthermore, as the component (A) in the present embodiment, lactams, diamines, dicarboxylic acids and / or ω-aminocarboxylic acids are polymerized to a low molecular weight oligomer stage in a polymerization reactor, and thereafter, in an extruder or the like. High molecular weight copolymerized polyamides can also be used.

  Preferable specific examples of the component (A) in the present embodiment include polyamide 6, polyamide 66, polyamide 46, polyamide 11, polyamide 12, polyamide 610, polyamide 612, polyamide MXD (m-xylylenediamine) 6, polyamide 6T. And polyamide 6I and one or more selected from the group consisting of copolymers containing at least one of these as a constituent component. These polyamides are preferable from the viewpoint of excellent mechanical strength.

  Polyamides obtained by further copolymerizing with two or more of these polyamide resins using an extruder or the like can also be used.

  Among the above, more preferable polyamide resins are polyamide 6, polyamide 66, polyamide 46, polyamide 11, polyamide 12, polyamide 610, polyamide 612, polyamide 6/66, polyamide 6/612, polyamide 66 / 6T. , Polyamide 66 / 6I, polyamide 6/12 / 6T, polyamide 66/12 / 6T, polyamide 6/12 / 6I, polyamide 66/12 / 6I, and polyamide 9T. Among these, from the viewpoint of strength, heat resistance, and durability, one or more selected from polyamide 6, polyamide 66, polyamide 610, polyamide 612, PA66 / 6T, and PA66 / 6I are more preferable.

<(B) component>
The (B) glass fibers in the present embodiment, the weight average fiber length X ([mu] m) and median D ₅₀ in the polyamide resin hollow molding body (Y) (μm) and the ratio (X / Y) is 1.6 or more If it is, it will not specifically limit, What is normally used together with a polyamide resin can be used. “In the polyamide resin hollow molded body” means that the component (A), the component (B) and other components as necessary constitute the polyamide resin composition of the present embodiment, This means that the X / Y ratio is specified for the component (B) after being processed. That is, the X / Y ratio measured for glass fibers (as raw materials) before being added to the polyamide resin composition of the present embodiment does not have to satisfy the above, and is added as a polyamide resin composition. Furthermore, the component (B) after the polyamide resin hollow molded body may satisfy the above range. By including the component (B), the polyamide resin hollow molded body of this embodiment can exhibit the desired strength and rigidity of this embodiment.

  In addition, the average fiber diameter of (B) glass fiber is not specifically limited, A public thing can be used suitably. For example, various forms of glass fibers such as chopped strands, rovings, and milled fibers having an average fiber diameter of 5 μm to 30 μm can be used.

  From the viewpoint of maintaining the balance between the strength and rigidity of the polyamide resin hollow molded body, the surface appearance, and the inner surface smoothness, the combined use of chopped strands and milled fibers is preferable. From the same viewpoint, it is more preferable that the proportion of chopped strands exceeds 50% by mass with respect to 100% by mass of the glass fiber.

The glass fiber (B) in this embodiment has a ratio (X / Y) of the weight average fiber length X (μm) to the median value D ₅₀ (Y) (μm) of 1.6 or more. The fiber length of the glass fiber was determined by observing the hollow resin molded body of the polyamide resin under an optical microscope after burning only the resin component contained in the hollow molded body of the polyamide resin in an electric furnace at 650 ° C., for example. The length of 500 glass fibers arbitrarily selected using an analyzer can be measured and specified.

The weight average fiber length, median value D ₅₀ , and number average fiber length are determined by the following formula. In addition, i in the formula is the order when the measured lengths L of the glass fibers are arranged in ascending order, and are the 250th fiber length (L ₂₅₀ ) and the 251st fiber length (L ₂₅₁ ). .
Weight average fiber length (X) = Σ (L _i ² ) / ΣL _i
Median value D ₅₀ (Y) = (L ₂₅₀ + L ₂₅₁ ) / 2
Number average fiber length (Z) = Σ (Li) / 500

(B) The ratio “X / Y” of the weight average fiber length (X) and the median value D ₅₀ (Y) of the glass fiber is a viewpoint of maintaining a balance between the strength / rigidity, appearance and inner surface smoothness of the polyamide resin hollow molded body. Therefore, it is 1.6 or more, preferably 1.9 or more, and more preferably 1.9 or more and 2.5 or less. On the other hand, when the X / Y ratio is less than 1.6, the balance between the strength / rigidity, appearance, and inner surface smoothness of the polyamide resin hollow molded article is impaired.

  (B) The weight average fiber length (X) of the glass fiber is preferably 100 μm or more and 500 μm or less from the viewpoint of maintaining the balance of strength / rigidity and appearance of the polyamide resin hollow molded body.

(B) The ratio “Z / Y” of the number average fiber length (Z) and the median value D ₅₀ (Y) of the glass fiber is a viewpoint of maintaining a balance between the strength / rigidity, appearance and inner surface smoothness of the polyamide resin hollow molded body. Therefore, 1.2 or more is preferable, 1.3 or more is more preferable, and 1.3 or more and 1.5 or less is more preferable.

  Although it does not specifically limit as a method of controlling the fiber length and median value of glass fiber to the desired range of this embodiment as described above, for example, when kneading with an extruder, 1) chopped strands as top feed 2) A method in which the feed is divided into side feeds, 2) a method in which a polyamide resin composition once kneaded with polyamide and chopped strands is top feed, a method in which chopped strands are fed into side feeds and extrusion kneaded in two stages, and 3) chopped strands 4) Method of feeding chopped strand from side feed and milled fiber from top feed using milled fiber together 4) Method of feeding chopped strand and milled fiber from both side feeds 5) Chopped strand And milled fiber And use both a method of introducing a top feed or side feed like the. Among the above, 4) a method of using chopped strands and milled fibers in combination and introducing them from two side feeds is preferable from the viewpoint of easy control of the glass fiber length. The control of the X, Y, and Z values in the present embodiment is not particularly limited, but can be appropriately adjusted by, for example, blending B1 and B2 in Examples described later. . For example, the values of X / Y and Z / Y can be increased by making the content ratio of B1 larger than the content ratio of B2.

  (A) The glass fiber (B) as a raw material to be kneaded with the polyamide resin is chopped strand having a number average fiber length of 1.5 mm or more and 9 mm or less, and a number average fiber length from the viewpoint of achieving both excellent mechanical strength and appearance. Is preferably a mixture with milled fiber of 1 mm or less. Furthermore, the ratio of the chopped strand is preferably more than 50% by mass and more preferably more than 70% by mass with respect to 100% by mass of the glass fiber from the viewpoint of mechanical strength.

  (B) The glass fiber to which a sizing agent or a silane coupling agent is attached is preferable. The type of the sizing agent or the silane coupling agent is not limited, and known materials can be used. Thereby, it exists in the tendency which can improve the adhesive force of a polyamide resin and glass fiber more.

  The sizing agent is not particularly limited, and examples thereof include a urethane polymer, a copolymer of maleic anhydride and an unsaturated monomer, and an acrylic acid copolymer.

  The silane coupling agent is not particularly limited. For example, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β (aminoethyl) -γ-aminopropyltrimethoxysilane, vinyltri Examples thereof include ethoxysilane and γ-glycidoxypropyltrimethoxysilane.

<Other ingredients>
In the polyamide resin composition in the present embodiment, various additives can be blended if necessary within a range not impairing the object of the present embodiment. Specifically, antioxidants such as hindered phenols and hindered amines; UV absorbers such as triazoles; heat stabilizers such as copper compounds and phosphorus compounds; photodegradation inhibitors such as manganese compounds; polyesters and glycerin Plasticizers; lubricants such as higher fatty acid metal salts such as metal stearates; mold release agents such as metal salts of montanic acid; nucleating agents such as talc; flame retardants such as magnesium hydroxide and melamine polyphosphate; Coloring pigments: Coloring dyes such as copper phthalocyanine derivatives may be added, or other thermoplastic resins may be blended.

  The method of blending the additive is not particularly limited, and examples thereof include a method of adding at the time of polymerization of the polyamide resin, a method of adding to the molten polyamide resin when melt-kneading with a twin screw extruder, and the like. It is done.

  Other thermoplastic resins that can be blended are not particularly limited. For example, a thermoplastic resin that is usually blended with a polyamide resin can be used. For example, polyphenylene ether and the like can be mentioned.

[Production Method of Polyamide Resin Composition]
The polyamide resin composition in the present embodiment is a mixture of (A) a polyamide resin, (B ′) chopped strands having a number average fiber length of 1.5 mm to 9 mm, and milled fibers having a number average fiber length of 1 mm or less. It can be produced by a method including a step of melt-kneading a certain glass fiber at a ratio of 25% by mass or more and 85% by mass or less of the component (A) and 15% by mass or more and 75% by mass or less of the component (B). Further, the ratio (X / Y) of the weight average fiber length X (μm) and the median value D ₅₀ (Y) (μm) of the component (B) in the polyamide resin composition is 1.6 or more. It is preferable to adjust. According to such a production method, it is possible to obtain a polyamide resin composition that not only ensures sufficient mechanical properties, but also has an excellent surface appearance of the molded body and excellent internal surface smoothness when formed into a hollow molded body. it can.

  The polyamide resin composition in this embodiment can also be manufactured by mixing various melt | fusion additives as needed other than (A) polyamide resin and (B) glass fiber, and melt-kneading. The blending, mixing and kneading methods and their order in that case are not particularly limited, and various known techniques can be applied for production. For example, it can be produced by a commonly used mixer or kneader.

  The mixer is not particularly limited, and for example, a Henschel mixer, a tumbler, a ribbon blender, or the like can be used. As the kneader, a single-screw or twin-screw extruder can be used. If necessary, a batch-type mixer, a plurality of conveying lines, a continuous mixer such as a quantitative feeder, or the like may be used.

[Production method of polyamide resin hollow molded body]
The production method for molding the polyamide resin composition in this embodiment to form a polyamide resin hollow molded body is not particularly limited. For example, a pellet containing the polyamide resin composition is produced by an extruder and the pellet is compressed. A desired resin product can be formed by molding into an arbitrary shape by molding, injection molding, extrusion molding or the like.

  The production method of the polyamide resin hollow molded body in more detail is not particularly limited. For example, a method of injecting a solid such as a sphere to pass through the inside of the molded body, water assist molding using a liquid such as water, nitrogen or the like And gas assist injection molding using the above gas. When molding a molded body having a hollow portion by such fluid-assisted molding, the inner surface smoothness can be improved, which is particularly useful.

  As a method of injecting the solid and allowing it to pass through the inside of the molded body, for example, the following procedure can be used. First, a floating core (for example, a sphere) is set in advance at one end in the mold cavity, and the amount of molten resin (polyamide in the present embodiment) is slightly larger than the required amount of the hollow molded body in the direction in which the floating core is pressed. The melt of the resin composition) is injected by a short shot method or a full shot method. Next, while the central portion of the injected molten resin is in a molten state, the floating core is pushed by the pressurized fluid. Then, the floating core moves to the discharge port at the other end of the mold cavity while pushing out the molten resin center portion having a relatively low viscosity and pressing the molten resin against the inner surface of the mold cavity. As a result, it is possible to obtain a hollow molded body having a uniform hollow portion and a smooth inner surface.

  The shape of the floating core may be, for example, a conical shape, a cannonball shape, a hemispherical shape, etc. when a hollow having a circular cross section is formed. In forming a multidimensional shape, a sphere is preferable. Moreover, as a material of a floating core, the same thermoplastic resin etc. as a metal and a molding material can be used. In addition, as a material of a floating core, what is hard and has heat resistance is preferable, for example, copper, brass, stainless steel, iron, aluminum etc. are mentioned. Further, the same thermoplastic resin as the molding material is preferable from the viewpoint of recycling.

  Although it does not specifically limit as said pressurized fluid, It is preferable that it is a thing of clean and appropriate temperature, For example, liquids, such as gas, such as air and nitrogen gas, water, and oil, can be used.

  Although it does not specifically limit as said gas assist injection molding, For example, it can carry out by either of the following 4 methods. That is, after injecting an insufficient amount of molten resin to fill the mold cavity, (1) injecting the gas body, (2) injecting the gas body, and then injecting the molten resin, (3) melting Examples thereof include a method of injecting a gas body while injecting a resin, and (4) injecting a gas body while injecting a molten resin and then injecting a molten resin.

  As a preferable specific example of the fluid-assisted molding, a method performed by the following procedure can be exemplified. First, a molten polyamide resin composition is injection-molded into a mold having a three-dimensional cavity having a minimum wall thickness of 5 mm or more, and after a predetermined time, the injection operation of the molten resin is stopped to solidify the mold surface. Next, water or compressed nitrogen gas or the like as a pressurized fluid is injected from the pressurized fluid injection part after a certain time into the molten resin in the cavity, a hollow part is formed inside the resin, and the pressure of the pressurized fluid is maintained. The resin in the cavity is cooled and solidified. Thereafter, the pressurized fluid in the hollow portion is opened to the atmosphere, the mold is opened, and the hollow molded body is taken out from the mold.

[Uses of polyamide resin hollow moldings]
The polyamide resin hollow molded body of this embodiment can be used in a wide range of fields and applications, and is suitable for automotive parts and furniture parts that require high appearance in addition to strength and rigidity. Among the above-mentioned, in the case of a molded body having a hollow portion, it is particularly suitable for automobile parts and the like whose inner surface smoothness is required. The molded body of this embodiment is not particularly limited.For example, an outer handle, an outer door handle, a wheel cap, a roof rail, a door mirror base, a rear mirror arm, a sunroof deflector, a radiator fan, a radiator grill, a bearing retainer, a console box, Sun visor arm, spoiler, sliding door rail cover, pipes such as cooling pipes, pedals such as accelerator pedals, legs of desks and chairs, seat rests, armrests, wheelchair parts, door handles, handrails, grip bars for bathrooms, It can be preferably used as an industrial molded body such as a window knob, a grating material, and the like, and a molded article for general goods.

  The shape of the polyamide resin hollow molded body of the present embodiment is not particularly limited as long as it has a hollow structure having at least an inlet portion and an outlet portion connected to the inlet portion, and can be molded into various forms.

  In the present embodiment, the polyamide resin hollow molded body is a hollow three-dimensional molded body, and the area ratio of the resin part / hollow part of the cross section is preferably 1/3 to 1/30, more preferably 1/5 to 1/30. When it has such an area ratio, it exists in the tendency which can reduce effectively the pressure loss of the entrance part of a polyamide resin hollow molded object, and an exit part. In addition, said "cross section" means the cross section when it cut | disconnects in the surface substantially perpendicular | vertical with respect to the length direction of a polyamide resin hollow molded object.

  Further, in this embodiment, when the polyamide resin hollow molded body is a hollow three-dimensional molded body and is molded by the above-described water assist method, the center line average of the hollow portion inner surface through which water has passed The roughness Ra is preferably 35 microns or more. The maximum height Rmax of the inner surface of the hollow part is preferably 250 microns or more. In addition, about said centerline average roughness Ra and maximum height Rmax, it cut | disconnects into two with a saw etc. along the axis line of a polyamide resin hollow molded object, and a surface roughness meter (For example, Mitutoyo Co., Ltd. product) , Surf test type SJ-400, etc.), with a measurement length of 1 cm and measuring five different points, the maximum surface roughness (Rmax) and the center line average roughness Ra can be measured.

The present embodiment will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples. The raw materials, measurement methods, and production methods used in Examples and Comparative Examples are shown below.

<Raw materials>
(A) Polyamide resin A1: Polyamide 66
Polyamide 66 used in Examples and Comparative Examples was polymerized by the following method. Add the equimolar salt of hexamethylenediamine and adipic acid, add the same amount of pure water as the total amount added, replace the inside of the polymerization can with N ₂ , start heating with stirring and maximize the pressure in the can. The final reaction temperature was adjusted to 300 ° C. while adjusting to 20 kg / cm ² . The polymer discharged into the water bath was pelletized with a strand cutter. The 98% sulfuric acid relative viscosity of the obtained polyamide 66 was 2.7 as a result of measurement according to JIS-K6920.

A2: Polyamide 610
The polyamide 610 resin used in the examples was polymerized by the following method. Add the equimolar salt of hexamethylenediamine and sebacic acid, add the same amount of pure water as the total amount added, replace the inside of the polymerization canister with N ₂ , start heating with stirring, and maximize the can internal pressure. The final reaction temperature was adjusted to 280 ° C. while reacting to 20 kg / cm ² . The polymer discharged into the water bath was pelletized with a strand cutter. The relative viscosity of the obtained polyamide 610 was 2.5 as a result of measurement according to JIS-K6920.

(B) Glass fiber B1: The chopped strand of the brand name "CS3J-454" by Nitto Boseki Co., Ltd. was used. The number average fiber length was 3 mm, and the average fiber diameter was 11 μm.
B2: A milled fiber having a cut length of 0.1 mm and an average fiber diameter of 11 μm and subjected to aminosilane treatment was used.
B3: A milled fiber having a cut length of 0.3 mm and an average fiber diameter of 11 μm and subjected to aminosilane treatment was used.

(C) Colorant The following were used.
C1: Nigrosine Product name “Nubiane Black (registered trademark) PA-9801 (manufactured by Orient Chemical Co., Ltd.)”
C2: Carbon black Trade name “Mitsubishi (registered trademark) carbon black # 960 (manufactured by Mitsubishi Chemical Corporation)”

<Measurement of average fiber length of glass fibers in polyamide resin hollow molded article>
A polyamide resin hollow molded body containing the components A to C was prepared, and only the resin component contained in the polyamide resin hollow molded body was burned in an electric furnace at 650 ° C., and then under an optical microscope (magnification: objective lens). The length of 500 glass fibers arbitrarily selected using an image analysis apparatus was measured.

The weight average fiber length, median value D ₅₀ , number average fiber length, and standard deviation were determined by the following formula. When the measured lengths of the glass fibers are arranged in ascending order, they are the 250th fiber length (L ₂₅₀ ) and the 251st fiber length (L ₂₅₁ ). The results are shown in Table 1.
Weight average fiber length (X) = Σ (Li ² ) / ΣLi
Median value D ₅₀ (Y) = (L ₂₅₀ + L ₂₅₁ ) / 2
Number average fiber length (Z) = Σ (Li) / 500

<Evaluation of mechanical properties: measurement of flexural modulus and flexural strength>
Using an injection molding machine (screw diameter 40 mm, manufactured by Nissei Plastic Industry Co., Ltd., FN-3000), cylinder temperature 290 ° C., mold temperature 80 ° C., injection pressure 65 MPa, injection time 25 seconds, cooling time 15 seconds, screw rotation speed A multi-purpose test piece A type conforming to ISO 3167 was molded under the molding condition of 200 rpm, and the test specimen for bending test was cut. The obtained specimen is an autograph (manufactured by Shimadzu Corp., AG-5000D type) according to ISO 178, and has a flexural modulus and a bending strength under conditions of a crosshead speed of 2 mm / min and an ambient temperature of 23 ° C. Measurements were made. The results are shown in Table 1.

<Evaluation of appearance of molded body>
Using an injection molding machine (screw diameter 40 mm, manufactured by Nissei Plastic Industry Co., Ltd., FN-3000), cylinder temperature 290 ° C., mold temperature 80 ° C., injection pressure 65 MPa, injection time 25 seconds, cooling time 15 seconds, screw rotation speed A flat plate (60 × 90 × 3 mm) was obtained under molding conditions of 200 rpm. The appearance of the obtained flat plate was evaluated according to the following criteria. The results are shown in Table 1.
◎: There is no float of glass, etc., and the surface is glossy ○: There is no surface gloss, but there is no float of glass, etc. △: There is a slight float of glass, etc. ×: The glass is severely floated

<Evaluation of pressure loss of hollow molded body>
The shape of the cavity provided in the mold for molding the injection molded body was a cylindrical shape having a diameter of 21 mm and a length of 500 mm. It put into the hopper equipped with the heating cylinder. The molding conditions were as follows.
Injection molding machine set temperature: 290 ° C, mold temperature: 80 ° C
Injection pressure: 1200 kgf / cm ²
Injection rate: 70cc / sec

After 1.4 seconds from the start of injection, the injection operation of the molten resin is stopped, and then 0.6 seconds later, compressed nitrogen gas having an initial pressure of 7 kgf / cm ² is injected as a pressurized fluid from the pressurized fluid injection portion, and further injected. 0.9 seconds after the start, water having an initial pressure of 200 kgf / cm ² was injected into the molten resin in the cavity as a pressurized fluid from the pressurized fluid injection part to form a hollow part inside the resin. The pressure of the pressurized fluid was maintained for 35 seconds, and the resin in the cavity was cooled and solidified. Thereafter, the pressurized fluid in the hollow portion was released, the mold was opened, and the hollow molded body was taken out from the mold.

  After sufficiently cooling the hollow molded body, the end of the hollow molded body is cut along the cross section of the cylindrical injection molded body with a saw so that the total length is 500 mm, and the inlet side and the outlet side of the ends The pressure loss was evaluated when 10 cc / sec water flowed through the hollow molded body. The pressure loss was evaluated by measuring the difference in gauge pressure between the pressure gauges on the inlet side and the outlet side. In the above measurement, five compacts having the same composition were prepared, their pressure loss was measured, and the maximum value among the five values obtained was the pressure loss of the example (or comparative example). It was. The results are shown in Table 1.

[Examples 1-9, Comparative Examples 1-6]
L / D (having an upstream supply port in the first barrel from the upstream side of the extruder, further having a downstream first supply port in the sixth barrel and a downstream second supply port in the ninth barrel, A twin screw extruder [ZSK-26MC: manufactured by Coperion (Germany)] with a cylinder length of the extruder / cylinder diameter of the extruder = 48 (the number of barrels: 12) was used. In the twin-screw extruder, the temperature from the upstream side supply port to the die was set at 290 ° C., the discharge amount was 25 kg / hour, and the screw rotation number was set to the numerical values shown in Table 1 below. Under such conditions, the above polyamide resin (PA), CuI and KI are respectively supplied from the upstream supply port so as to have the ratio described in the upper part of Table 1 below, and from the downstream first supply port (B2 ) Was supplied from the downstream second supply port. And the pellet of the resin composition was manufactured by melt-kneading these. After drying so that the moisture of the pellet of the obtained resin composition might be 800 ppm or less, the above-mentioned various moldings and evaluations were performed. These evaluation (counting) results are shown in Table 1. In addition, A component and B component in Table 1 are shown by the content rate (mass%) with respect to the total mass of A component and B component. Moreover, C component in Table 1 has shown by the mass part when the sum total mass of A component and B component is set to 100.

  In Examples 1 to 9 where X / Y of the polyamide resin hollow molded body is 1.6 or more, it is recognized that the bending elastic modulus / bending strength, the surface appearance, and the pressure loss of the hollow molded body are all excellent in balance. It was. As described above, it was confirmed that the polyamide resin hollow molded body of this example was excellent not only in mechanical properties but also in the surface appearance of the molded body and the inner surface smoothness of the hollow portion. On the other hand, all of Comparative Examples 1 to 6 were evaluated as having a poor balance of flexural modulus / bending strength, surface appearance, and inner surface smoothness of the hollow molded body.

  The polyamide resin hollow molded body according to the present invention is excellent in mechanical properties and appearance of the molded body, and can reduce the roughness of the inner surface of the hollow portion. Therefore, the polyamide resin hollow molded body has a wide range including various automobile parts and furniture parts. It can be used in fields and applications and is very useful in industry.

Claims (6)

25% by mass or more and 85% by mass or less (A) polyamide resin, 15% by mass or more and 75% by mass or less (B) glass fiber,
A polyamide resin hollow molded body comprising a polyamide resin composition comprising:
The ratio (X / Y) of the weight average fiber length X (μm) and the median value D50 (Y) (μm) of the (B) glass fiber in the polyamide resin hollow molded body is 1.6 or more.
Polyamide resin hollow molded body.   The component (A) is a polyamide 6, polyamide 66, polyamide 46, polyamide 11, polyamide 12, polyamide 610, polyamide 612, polyamide MXD6, polyamide 6T and polyamide 6I and a copolymer containing at least one of these as a constituent component The polyamide resin hollow molded article according to claim 1, which is at least one selected from the group consisting of:   The polyamide resin hollow molded body according to claim 1 or 2, wherein a weight average fiber length of the component (B) in the polyamide resin hollow molded body is 100 µm or more and 500 µm or less.   The ratio (Z / Y) of the number average fiber length Z (μm) of the component (B) and the median value D50 (Y) (μm) in the polyamide resin hollow molded body is 1.2 or more. The polyamide resin hollow molded body according to any one of 1 to 3.   5. The component (B) is a mixture of chopped strands having a number average fiber length of 1.5 mm or more and 9 mm or less and milled fibers having a number average fiber length of 1 mm or less. Polyamide resin hollow molded body.   The polyamide resin hollow molded body according to claim 5, wherein a ratio of the chopped strands to 100% by mass of the component (B) exceeds 50% by mass.