JPH09137058A - Polyamide resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the above composition, having excellent mechanical characteristics and heat resistance, excellent in friction and abrasion resistances and useful for sliding members, etc., by blending nylon 46 resin with potassium titanate whiskers and an ultrahigh-molecular weight polyethylene resin powder. SOLUTION: This polyamide resin composition is obtained by blending (A) 60-90wt.% nylon 46 resin and (B) 10-40wt.% potassium titanate whiskers with (C) an ultrahigh-molecular weight polyethylene resin powder with the proviso that the intrinsic viscosity [η] measured in a decalin solvent at 135 deg.C is >=10dl/g; the total amount substantially passes through a 100-mesh screen; at least >=20wt.% passes through a 350-mesh screen and the average particle diameter is <=80μm} in an amount of 0.1-5 pts. by wt. based on 100 pts. by wt. total amount of the components (A) and (B).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for sliding members which has excellent abrasion resistance and abrasion resistance. More specifically, the present invention relates to a polyamide resin composition for sliding members, which has a high limit PV value, a small amount of wear including a dynamic friction coefficient and a mating material, and is excellent in heat resistance and rigidity.

[0002]

2. Description of the Related Art Polyamide resins have large changes in mechanical strength and dimensional changes due to moisture absorption, but have many excellent properties required for engineering plastics, such as toughness, heat resistance and chemical resistance. Moreover, the polyamide resin is remarkably excellent in self-lubricating property as compared with other engineering plastics. Therefore, when it is used for bearing parts, gear parts, or machine parts that require wear resistance, it can be used without a lubricant and has low noise, and is useful as a substitute material for metal materials. Among them, nylon 46 resin is excellent in heat resistance and also excellent in fluidity characteristics at the time of molding.

Recently, the fields of application of plastic sliding members have been expanded, and bearings that are non-lubricated and are subject to severe wear, severe wear, bushings used under high ambient temperature conditions, and parts that are light, thin, short and small. As a result, the field of application is expanding to fields such as thin-walled sliding parts, and as the field of application expands, the performance requirements for plastic sliding members are becoming stricter.

While plastics materials are excellent in self-lubricating property, they have a drawback that they have a lower limit PV value and inferior mechanical strength such as rigidity as compared with metal materials. The limit PV
The value is generally the limit value of the load at which the material melts or seizes when the sliding member exceeds a certain speed at a certain load.

Generally, when plastic is applied to sliding parts such as bearings, in addition to the friction and wear characteristics that the dynamic friction coefficient is small, the limit PV value is large, the amount of wear is small, and the mating material is not damaged, rigidity and It is desirable to use a material that has excellent mechanical properties such as creep resistance.

[0006] Conventionally, various methods have been investigated for improving mechanical properties and heat distortion temperature while maintaining or improving the friction and wear properties of polyamide resins. For example, glass fiber and polytetrafluoroethylene (PTF
E) and a method of combining carbon fiber and molybdenum disulfide have been proposed. However, the conventional method as described above has the following drawbacks.

That is, for example, when polyamide containing glass fiber and PTFE is used as a bearing material, the glass fiber is microscopically exposed on the bearing sliding surface and wears the mating material, which is the so-called "galling". Have
There is a drawback that not only the amount of wear increases, but also the coefficient of friction increases. Further, for example, a polyamide resin composition in which carbon fiber and molybdenum disulfide are added is very expensive because both carbon fiber and molybdenum disulfide are expensive, and "galling" to the mating material is fundamentally high. There are drawbacks that have not been resolved. Further, since the glass fiber and the carbon fiber have a relatively long fiber length of about 3 mm, the anisotropy of the composition molded body using these is large, and it is difficult to design the molded body die. There is also a problem with dimensional accuracy.

In order to improve defects such as so-called "galling" of a molded article molded from a composition obtained by adding a relatively long and hard fiber such as glass fiber and carbon fiber to a polyamide resin, and anisotropy at the time of molding, Potassium titanate whiskers, which are microfibers than fibers and carbon fibers (hereinafter,
The above-mentioned drawbacks cannot be eliminated by a system in which PTW) is only added to polyamide. That is, when the polyamide resin is mixed with PTW alone, the limiting PV value and the mechanical properties are improved, but the specific wear amount is rather increased.
The fatal defect as a material for a sliding member that the wear resistance is lowered has not been solved.

[0009]

The present invention has been made in view of the above circumstances, and its purpose is nylon 4
6 It is to obtain a resin composition for a sliding member, which is excellent in abrasion resistance and abrasion resistance while maintaining excellent mechanical properties and heat resistance of 6 resin.

[0010]

As a result of intensive studies by the present inventors, a resin composition for a sliding member obtained by blending nylon 46 resin with powdered ultra high molecular weight polyethylene (hereinafter referred to as UHPE) and PTW. By using things,
Not only the mechanical properties of the sliding member are improved, but also PTW
The present invention has been completed by finding an unexpected effect that the dynamic friction coefficient and the wear amount decrease as the blending amount increases.

That is, the present invention relates to (A) nylon 46
(C) Ultra high molecular weight polyethylene resin powder per 100 parts by weight of the total amount of the (A) component and the (B) component based on 60 to 90% by weight of the resin and 10 to 40% by weight of the (B) potassium titanate whiskers. Polyamide resin composition blended in an amount of 0.1 to 5 parts by weight [however, ultrahigh molecular weight polyethylene powder refers to an intrinsic viscosity [η] measured in a decalin solvent at 135 ° C of 10 dl / g or more and 100 mesh sieve. Of a polyethylene powder having an average particle size of 80 μm or less and having passed through a 350 mesh sieve at least 20% by weight or more].

The present invention will be described in detail below.

The nylon 46 resin (A) used in the present invention is obtained by a condensation reaction using adipic acid or a functional derivative thereof as an acid component and tetramethylene diamine or a functional derivative thereof as an amine component. The polyamide is mainly used, but a polyamide in which a part of the adipic acid component or the tetramethylenediamine component is replaced by another copolymer component may be used.

Preferred embodiments of the nylon 46 resin are described in JP-A-56-149430 and JP-A-56-14943.
No. 1 publication.

The nylon 46 resin used in the present invention comprises:
It is necessary that the intrinsic viscosity when measured at 35 ° C. using m-cresol is in the range of 0.80 to 1.90,
It is preferably in the range of 0.90 to 1.50.

Nylon 46 with an intrinsic viscosity of more than 1.90
In the case where is used, the fluidity at the time of molding is poor, and not only is the gloss of the appearance of the obtained molded article lost, but also its mechanical properties and thermal properties are greatly varied, which is not preferable. On the other hand, when the intrinsic viscosity is lower than 0.80, a disadvantage occurs in that the mechanical strength of the molded product is reduced.

The component (B) used in the present invention, potassium titanate whiskers (PTW), has the general formula:

[0018]

[Image Omitted] K ₂ O · n (TiO ₂ ) or general formula:

[0019]

Embedded image A single crystal fiber represented by K ₂ O · n (TiO ₂ ) · 1 / 2H ₂ O (wherein n represents an integer of 2 to 8), and specifically, for example, 4-titanic acid. Potassium fiber,
It may be a single composition such as potassium hexatitanate fiber or potassium octatitanate fiber or a mixed composition thereof, with an average fiber diameter of 2 μm or less and an average fiber length of 5 to 100 μm.
m and the average fiber length / average fiber diameter (hereinafter, referred to as aspect ratio) is 10 or more. The average fiber diameter and the average fiber length of PTW are the average values measured by a scanning electron microscope for at least 5 fields of view and for at least 10 fibers per field of view, and the aspect ratio is It is a value calculated using the average value. When the average fiber diameter, the average fiber length and the aspect ratio of PTW are out of the above ranges, for example, when the aspect ratio is less than 10, the reinforcing effect when added to a resin or the like becomes small, which is not preferable. On the other hand, the average fiber length is 100
Fibers longer than μm are difficult to manufacture industrially and are not yet commercially available.

As the PTW used in the present invention, those commercially available under the trade names of "TISMO" (manufactured by Otsuka Chemical Co., Ltd.) and "Tybrex" (manufactured by Kawatetsu Mining Co., Ltd.) are used as they are. It can also be used, which has an average fiber diameter of 0.2 to 0.5 μm and an average fiber length of 10 to 20.
It is a high-strength single crystal whisker having a micrometer and an aspect ratio of 20 to 100.

The PT of the component (B) used in the present invention
The blending amount of W is the sum of the components (A) and (B) used in the present invention from the viewpoints of the reinforcing effect of the polyamide resin, especially the improvement of rigidity, creep resistance and heat distortion temperature, and the improvement of the critical PV value. It is preferably from 10 to 40% by weight of the amount. If the blending amount is less than 10% by weight, the mechanical strength cannot be sufficiently improved, and even if it is used in excess of 40% by weight, the effect of improving the mechanical strength with respect to the amount used is increased by 40% by weight. It is not recognized, and it becomes difficult to granulate the composition as a molding material.

The PTW may be used without surface treatment, but in order to improve the interfacial adhesion strength between the PTW and the polyamide resin, a surface treatment agent such as a silane coupling agent such as epoxysilane, aminosilane or acrylsilane, or It is preferable to use it after subjecting it to a surface treatment such as a titanate coupling agent, and such surface treatment is extremely effective for improving the physical properties of the molded article under dry or wet conditions.

The ultrahigh molecular weight polyethylene (C) used in the present invention means a homopolymer of ethylene or a small amount of other α-olefins such as propylene, 1-butene, 1-hexene, 1-octene and 4-. It is a copolymer with methyl-1-pentene or the like and has an intrinsic viscosity [η] in a decalin solvent at 135 ° C. of 10 dl / g or more, preferably in the range of 15 to 30 dl / g. When [η] is less than 10 dl / g, the molecular weight is small and the effect of improving wear resistance is small.

The ultrahigh molecular weight polyethylene powder used in the present invention has a specific particle size. That is, its particle size is such that substantially all of it passes through a 100-mesh screen and at least 20% by weight, preferably 50% by weight or more, through a 350-mesh screen, and an average particle size of 80 μm or less, preferably 3 to 60 μm, and further It is preferably in the range of 3 to 40 μm. If a powder having a large particle size that remains on the 100-mesh screen exists, even if the powder is melt-kneaded with the nylon 46 resin (A), the powder has a large particle size and a large sea-island structure, resulting in a poor dispersion state.
It is not preferable because it is inferior in impact resistance and mechanical properties.

The ultra high molecular weight polyethylene powder used in the present invention has at least 2 components that pass through a 350 mesh sieve.
Since it is 0% by weight or more and the average particle size is within the above range, a composition having good dispersibility in nylon 46 resin (A) and excellent in abrasion resistance, impact resistance and mechanical properties can be obtained. . When the average particle size exceeds 80 μm, the dispersibility is poor and the above properties are not improved. On the other hand, the lower limit of the average particle size is not particularly limited, but in the case of fine powder having a particle size of less than 3 μm,
Due to the low bulk specific gravity, it is difficult to handle the powder,
It may be difficult to uniformly mix with the nylon 46 resin (A).

The ultrahigh molecular weight polyethylene powder (C) used in the present invention preferably has a spherical shape, a flattened spherical shape, or a fan shape in which small spheres are associated.

The ultrahigh molecular weight polyethylene powder used in the present invention is modified by introducing at least one polar group consisting of acid, ester, amide, acid anhydride and epoxide groups into all or a part thereof. If you leave it, nylon 4
6 Affinity with resin (A) is improved, and mechanical properties are further improved, which is preferable. As a method for introducing a polar group, for example, a modification method in which a graft monomer having a polar group is graft-copolymerized with ultra high molecular weight polyethylene powder is adopted.

The blending amount of the ultra high molecular weight polyethylene powder used in the present invention is the total amount of the components (A) and (B) is 1
It is preferably 0.1 to 5 parts by weight per 00 parts by weight. If the blending amount is less than 0.1 parts by weight, the abrasion resistance is not sufficiently improved, and if it exceeds 5 parts by weight, the melt fluidity is deteriorated and injection molding becomes difficult, and the nylon 46 resin (A ) Greatly impairs the original characteristics.

The composition of the present invention comprising the above polyamide resin, UHPE and PTW may optionally contain PTF.
A lubricant such as E, MoS ₂ , graphite and silicone oil may be appropriately added and used.

If desired, a pigment or other compounding agent may be added to the resin composition of the present invention in an expression amount.
Examples of such a compounding agent include fillers other than PTW, for example, fibrous substances such as aramid fibers, powdery, granular or plate-like inorganic fillers such as calcium carbonate, barium sulfate and mica.

These fillers are usually blended as a reinforcing material, a surface modifier, or for the purpose of modifying electrical and thermal properties, etc. It should be blended within a range that does not lose the excellent properties inherent to the product and the advantages in molding.

Further, for the purpose of improving heat resistance, an antioxidant or a heat stabilizer such as a copper compound such as copper iodide, a hindered phenol compound, an aromatic amine compound, an organic phosphorus compound or a sulfur compound may be added. . Various epoxy compounds, oxazoline compounds and the like may be added for the purpose of improving the melt viscosity stability and hydrolysis resistance. As the epoxy compound used for such purpose,
Bisphenol-A type epoxy compound obtained by reacting bisphenol-A and epichlorohydrin, aliphatic glycidyl ether, novolac type epoxy compound, aromatic or aliphatic carboxylic acid type epoxy compound obtained by reaction of various glycols or glycerol with epichlorohydrin , Alicyclic compound type epoxy compounds and the like are preferable, and as the oxazoline compound, aromatic or aliphatic bisoxazoline, particularly 2,2′-bis (2-oxazoline), 2,2′-m-phenylenebis (2-oxazoline) Is preferred.

Other stabilizers, colorants, lubricants, ultraviolet absorbers and antistatic agents can also be added and used.

Furthermore, a small amount of other thermoplastic resin such as other polyamide resin, polyester resin, polyphenylene sulfide resin, polyphenylene ether resin, polycarbonate resin, phenoxy resin, polystyrene and its copolymers, acrylic resin and acrylic resin. You may mix | blend type | system | group copolymer, polyamide elastomer, polyester elastomer, and thermosetting resin, for example, phenol resin, melamine resin, unsaturated polyester resin, silicone resin etc.

Any compounding method can be used to obtain the resin composition of the present invention.

Usually, it is preferable to disperse these compounding components more uniformly, and a method of mixing all or part of them simultaneously or separately with a mixer such as a blender, a kneader, a roll or an extruder for homogenization, It is possible to use a method in which a part of the mixing portion is mixed simultaneously or separately with, for example, a blender, a kneader, a roll, an extruder, etc., and the remaining components are mixed with these mixers or an extruder to homogenize. Further, there is a method in which a composition dry-blended in advance is melt-kneaded by a heated extruder to homogenize it, then extruded into a wire shape, and then cut into a desired length and granulated.

The molding composition produced in this way is
Usually, it is kept in a sufficiently dried state and put into a hopper of a molding machine to be used for molding such as injection molding. Furthermore, it is also possible to dry blend the constituent materials of the composition, directly charge them into a molding machine hopper, and melt-knead them in a molding machine.

[0038]

The present invention will be described in detail with reference to the following examples.

Nylon 46 resin (STANYL, manufactured by DSM, Netherlands), potassium titanate whiskers (Tybrex HPA, manufactured by Kawatetsu Mining Co., Ltd.), ultra high molecular weight polyethylene having a number average molecular weight of about 2 million (Miperon XM-).
220, Mitsui Petrochemical Industry Co., Ltd. and glass fiber (10 μ diameter, manufactured by Nippon Electric Glass Co., Ltd.) with the composition of composition (unit: parts by weight) of the twin-screw extruder with vent (manufactured by Japan Steel Works) , TEX44) and extruded at 280 to 310 ° C. to obtain pellets. All polyamides were dried at 110 ° C. under a reduced pressure of 10 Torr for 8 hours or more prior to compounding,
The water content was 0.1% or less.

The molding conditions, the shape of the molded article, and various properties in the examples were measured according to the following methods. (1) Molding conditions Molding machine: Toshiba IS75E Cylinder temperature: 280-300 ° C Mold temperature: 120 ° C (2) Mechanical properties Tensile strength: Compliant with ASTM D638. Bending test: According to ASTM D790. Weighted deflection temperature: In accordance with ASTM D648, weighted 1
It was measured at 820 kPa. (3) Sliding test According to JIS K 7218 (a) method, the sliding condition for aluminum material (1050) specific wear amount and dynamic friction coefficient is sliding speed: 15 cm / sec, load: 40 kgf, time: 1
It was calculated as 800 seconds.

[Examples 1 and 2, Comparative Examples 1 to 3] Example 1
~ 2 is an example in which potassium titanate whiskers (PTW) and ultra-high molecular weight polyethylene (UHPE) are added to nylon 46 resin in an amount that expresses its function. While maintaining excellent strength and elastic modulus, a high weighted deflection temperature is obtained. As shown, it has very good heat resistance. Furthermore, it has extremely excellent sliding characteristics, and not only the amount of wear of the polyamide resin composition sample itself is extremely small, but also the amount of wear of aluminum, which is a mating material during sliding, is extremely small.

Comparative Examples 1 and 2 are examples in which potassium titanate whiskers (PTW) were added to nylon 46 resin,
Excellent mechanical properties and heat resistance, but poor sliding properties.

Comparative Example 3 is an example in which glass fiber is added to nylon 46 resin. In addition to the large amount of wear of the polyamide resin composition sample itself, the amount of wear of the mating material aluminum is extremely large, and the sliding characteristics Inferior to.

[0044]

[Table 1]

[0045]

EFFECTS OF THE INVENTION The polyamide resin composition of the present invention has excellent mechanical properties and heat resistance, and is extremely excellent in abrasion resistance and abrasion resistance, and is suitably used as a polyamide resin composition for sliding members. Can be done.

Claims (1)

[Claims] 1. (A) 60 to 90% by weight of nylon 46 resin and (B) 10 to 40 potassium titanate whiskers.
Polyamide resin composition obtained by blending 0.1 to 5 parts by weight of (C) ultra high molecular weight polyethylene resin powder with respect to 100% by weight of the total amount of the components (A) and (B), based on weight%. Ultra high molecular weight polyethylene powder is 135 ℃
Intrinsic viscosity [η] measured in decalin solvent of 10 dl
/ G or more, substantially 100% through a 100 mesh sieve,
And a polyethylene powder having an average particle size of 80 μm or less, which has passed through a 350-mesh sieve at least 20% by weight or more].