JP3568663B2 - Polyamide resin composition and sliding member - Google Patents

Description

【００３３】
【表２】

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a molded article material, in particular, an oilless bearing for an OA device, an automobile, a VTR component, or the like, a member such as a gear, which requires friction and wear resistance, and a resin composition suitable for the member. More specifically, the present invention provides a thermoplastic resin composition having improved mold deposits at the time of molding, remarkably suppressed generation of decomposition gas and the like at the time of molding, and having excellent mechanical properties and friction and wear characteristics. Sliding member.
[0002]
[Prior art]
Conventionally, resins having excellent friction and wear properties have a structure with few branches in molecular structure, that is, resins such as polyethylene, polytetrafluoroethylene, and polyacetal, and heat-resistant resins depending on the purpose of use, that is, semi-aromatic nylon and polyphenylene. Sulfides, polyetheretherketones, polyamideimides and the like have been used.
[0003]
In recent years, the technology of polymer alloys has been advanced, and the friction and wear characteristics have been improved by adding various polymers and low molecular weight compounds such as oils and metal soaps. However, polymers having good friction and wear properties exhibit excellent friction and wear behavior by themselves, but their use is limited due to problems of dimensional accuracy and rigidity with respect to precision parts such as OA equipment.
[0004]
Polyacetal and polyethylene are widely used as gears in VTRs and other precision equipment as materials with extremely excellent friction and wear properties.However, they have low heat resistance and have high precision dimensions due to the problem of dimensional accuracy. At present, the use of the required parts is also restricted.
On the other hand, in the improvement of friction and wear characteristics by addition of an oil or a low molecular weight compound, there are problems such as bleeding out to the surface of a molded article due to molding at a high temperature during injection molding, and deterioration of physical properties due to addition.
[0005]
Recently, polyethylene alloys and polytetrafluoroethylene have been added to these friction and abrasion resistant materials for the purpose of further improving the friction and abrasion properties without deteriorating the physical properties of the base polymer with excellent friction and abrasion properties by using polymer alloy technology. Further, a friction and wear resistant material to which a compatibilizer is added has been developed for the purpose of improving the interface strength between different kinds of resins, such as oil and various inorganic fillers.
[0006]
However, these resins and oils added for the purpose of improving the friction and wear characteristics are poor in heat stability in the temperature range where they are blended with a base, so-called engineering plastic and injection molded, and the polymer and additives contained in the polymer are poor. There is a problem that gas is generated by decomposition and causes a mold deposit.
[0007]
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a composition having excellent dimensional stability and friction and wear resistance, and having excellent sliding properties that do not generate mold deposit during molding.
[0008]
[Means for Solving the Problems]
By preparing a masterbatch in advance using an alkoxysilane- modified polyolefin and a base polyamide resin and / or a polyamide resin having a melting point lower than that, and adding the masterbatch to the base polyamide resin as a friction and wear property improving agent, a higher friction than before can be obtained. The present inventors have found that the generation of mold deposit can be significantly suppressed while having abrasion characteristics, and have completed the present invention.
[0009]
That is, the present invention
(A) 90 to 50% by weight of a melt-processable polyamide resin;
(B) an alkoxy silane modified polyolefin resin 10-99 wt% and above (A) masterbatch resin 10-50 wt obtained by kneading a polyamide resin 1-90 wt% with polyamide resin and / or melting point lower than that %, And
[0010]
(C) 0.001 to 5 parts by weight of a phosphite, a phosphate, a phenol-based stabilizer or a sulfur-based heat stabilizer based on 100 parts by weight of the components (A) and (B) in total. And a sliding member obtained by molding the same.
In the present invention, the sliding member means a member which is rubbed with another member such as a guide roll such as a tape or a gear.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the components constituting the composition of the present invention will be described in detail. The polyamide resin (A) used in the present invention is not particularly limited as long as it can be melt-processed, and a commercially available polyamide resin can be used. Preferably, the polyamide resin has a high molecular weight in order to improve the friction and wear resistance. Is used. In general, a polyamide having a melting point of 200 ° C. or more is preferable. In consideration of compatibility with the alkoxysilane- modified polyolefin, processing temperature, and the like, the polyamide is a crystal such as polyamide 66, polyamide 6, semi-aromatic polyamide, polyamide 46, or the like. Polyamides are preferred, and polyamides which have not been subjected to treatment such as acetylation at the polymer terminals and have polar groups such as amino groups and carboxyl groups are desirable.
[0012]
The masterbatch of (B) 10 to 99% by weight of an alkoxysilane- modified polyolefin resin used in the present invention and (A) 1 to 90% by weight of a base polyamide resin and / or a polyamide resin having a melting point lower than that of the masterbatch is defined by the present invention. And a component that suppresses the generation of mold deposits of a thermoplastic resin and acts as a friction and wear property improver.
[0013]
The polyamide resin used in the preparation of the masterbatch may be the same as the base (A) polyamide resin, but has a lower melting point than the base polyamide resin (A), preferably 5 in consideration of moldability. It is more preferable to use a polyamide having a low melting point of at least 10 ° C, more preferably at least 10 ° C, particularly preferably at least 20 ° C. For example, if the base polyamide (A) is polyamide 66, a soft polyamide such as polyamide 11 or polyamide 12 is preferred.
[0014]
The polyamide used for preparing the masterbatch of the present invention may be an amorphous polyamide whose melting point is not observable. Also, the alkoxysilane-modified polyolefin used in the present invention, low density polyethylene, high density polyethylene, polypropylene, ethylene-propylene block copolymer and the polyolefin such as ethylene-butene-1 copolymer modified with alkoxysilane down Monodea Ru.
[0015]
Modification with a modifier can be obtained by copolymerizing an olefin and a modifier, in addition to a method of adding or grafting a modifier to a polyolefin. Among them, an alkoxysilane-modified polyethylene (manufactured by Mitsubishi Chemical Corporation; trade name: Linklon), which is obtained by grafting or copolymerizing vinyltrimethoxysilane, which easily forms a gel and has high reactivity, is preferable . Particularly the gel fraction of the alkoxy silane-modified polyethylene according to the friction and wear characteristics required performance is possible by changing the master batch manufacturing conditions. Further, the modified polyolefin of maleic anhydride-modified or diene containing may be used in combination with the alkoxy silane-modified polyolefin for the purpose of further improvement of compatibility.
[0016]
In the present invention, the mechanism by which the masterbatch contributes to the suppression of the generation of deposits and the improvement of friction and wear resistance is not necessarily clear, but the modified site of the modified polyolefin reacts with a polymer terminal or a low molecular weight substance generated by hydrolysis or the like to decompose. It is presumed that by preventing the generation of gas or by adding the modified polyolefin, a gel is generated by intramolecular and / or intermolecular cross-linking, thereby suppressing the deposit generated by the gas generated during ordinary polyolefin decomposition. .
[0017]
As the heat stabilizer (C) used in the present invention, such as a phosphite or a phosphate, a commercially available heat stabilizer can be used. Further, any of phenol-based and sulfur-based heat stabilizers may be used. Taking into account the molding temperature, a material having a high decomposition temperature and high sublimation temperature is preferable, but is not particularly limited.
Specifically, for the phosphite and the phosphate, an alkyl, alkylene, aryl, alkaryl, aryl, or alicyclic compound having an OH group and an ester of phosphorous acid or phosphoric acid may be used. it can.
[0018]
Particularly, triphenyl phosphite and tetrakis (2,4-di-t-butyl-4-methylphenyl) pentaerythritol-diphosphite are preferred.
As the phenolic stabilizer, a compound having a hindered phenol structure is used, and specifically, triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3 , 5-Di-tert-butylanilino) -1,3,5-triazine, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,2-thio -Diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t-butyl- -Hydroxyphenyl) propionate, 2,2-thiobis (4-methyl-6-t-butylphenol), N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamide) , 3,5-di-t-butyl-4-hydroxy-benzylphosphonate-diethyl ester, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4 -Hydroxybenzyl) benzene, tris- (3,5-di-t-butyl-4-hydroxybenzyl) -isocyanurate, N, N'-bis [3- (3,5-di-t-butyl-4 -Hydroxyphenyl) propionyl] hydrazinedibutylhydroxytoluene, 4,4'-butylidenebis- (6-t-butyl-3-methylphenol), 2,2'-methylenebis (4-methyl-6-t-butylphenol), 1,3,5-tris (3 ', 5'-di-t-butyl-4'-hydroxybenzyl) -S-triazine-2,4,6 (1H , 3H, 5H) -Trione, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 4,4'-butylidenebis (3-methyl-6-tert-butylphenol) N-octadecyl-3- (4'-hydroxy-3 ', 5'-di-tert-butylphenyl) propionate, tetrakis [methylene-3- (3', 5'-di-tert-butyl-4-hydroxy) Phenyl) propionate] methane, 2,2-thio-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 3,9-bis [1,1-dimethyl-2} β- (3 t-butyl-4-hydroxy-5-methylphenyl) propionyloxyethyl] -2,4,8,10-tetraoxaspiro [5,5] undecane and 1,3,5-trimethyl-2,4,6 Tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene can be mentioned.
[0019]
Examples of the sulfur-based stabilizer include didecyl 3,3'-thiobispropionate, dioctadecyl 3,3'-thiobispropionate, and bis [2-methyl-4- {3-n-alkylthiopropionyl]. Oxy {-5-t-butylphenyl] sulfide, tetrakis [methylene-3- (dodecylthio) propionate] methane, ditridecylthiodipropionate, 4,4'-thiobis- (6-t-butyl-3-methylphenol ), Dilauryl thiodipropionate, distearyl thiodipropionate and dimyristyl thiodipropionate.
[0020]
Furthermore, (D) various kinds of fibrous, powdery, and plate-like inorganic fillers can be added to the resin composition of the present invention according to the purpose of use. Examples of the fibrous filler include inorganic fibers such as glass fiber, carbon fiber, silica fiber, silica / alumina fiber, alumina fiber, asbestos fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate, and wollastonite. Substances. Examples of powdery and plate-like fillers include carbon black, graphite, silica, glass beads, milled glass fiber, calcium silicate, aluminum silicate, talc, mica, iron oxide, titanium oxide, antimony trioxide, molybdenum disulfide and the like. Can be These fillers can be used alone or in combination of two or more. Further, as the inorganic filler used in the present invention, those subjected to various surface treatments depending on desired physical properties can also be used.
[0021]
In the present invention, the composition of the resin composition is as follows. That is, (A) 90 to 50% by weight, preferably 90 to 60% by weight, more preferably 90 to 70% by weight, and (B) 10 to 99% by weight of the modified polyolefin resin which can be melt-processed, and (A) A resin component comprising 10 to 50% by weight, preferably 10 to 40% by weight, more preferably 10 to 30% by weight of a masterbatch resin of 1 to 90% by weight of a polyamide resin and / or a polyamide resin having a lower melting point. (C) 0.001 to 5 parts by weight, preferably 0.001 to 1 part by weight, more preferably 0.1 to 1 part by weight, based on 100 parts by weight, of a phosphite, a phosphate, a phenol-based or a sulfur-based heat stabilizer. 001 to 0.3 parts by weight.
[0022]
The content of the modified polyolefin in the masterbatch resin (B) is preferably 30 to 99% by weight, more preferably 50 to 99% by weight.
The masterbatch is prepared and added in order to suppress the occurrence of mold deposit and to improve the sliding properties. There is no problem if the masterbatch is within the above range, but from the viewpoint of friction and wear properties and physical properties, 10 wt% or less. In this case, the effect of improving the friction and wear characteristics is small, and if the content exceeds 50% by weight, the mechanical strength is significantly reduced.
[0023]
Further, with respect to the gel fraction of the masterbatch, if the gel fraction is lower than 10% by weight, the effect of suppressing the deposit is small, and if it is higher than 90% by weight, the dispersion in the resin becomes extremely poor and the physical properties may be deteriorated. There is. Therefore, the gel fraction must be in the range of 10 to 90% by weight, preferably 20 to 60% by weight, and more preferably 20 to 50% by weight.
[0024]
In kneading the components (A), (B) and (C), first, the modified polyolefin resin of the component (B) and the polyamide resin are kneaded to prepare the component (B), and the component (A) is kneaded.
Thus, by kneading the modified polyolefin resin with the polyamide resin in two stages, a resin composition having excellent mechanical properties can be obtained.
[0025]
The phosphite, phosphate, phenol-based stabilizer and sulfur-based stabilizer of component (C) are generally added at the time of kneading components (A) and (B) to avoid thermal decomposition. However, when a stabilizer with little decomposition is used, it may be added during preparation of the masterbatch resin.
Furthermore, in the resin composition of the present invention, other thermoplastic resin is added as a sliding component other than the masterbatch which is added as a friction and wear resistant component in a range not to impair the effect of the present invention. Is also good. The thermoplastic resin used in this case is not particularly limited, and examples thereof include fluororesins, elastomers such as ABS and silicone rubber, and the like. These thermoplastic resins can be used as a mixture of two or more.
[0026]
Furthermore, the resin composition of the present invention also requires known additives such as ultraviolet absorbers such as resorcinol, salicylate, benzotriazole, and benzophenone, antistatic agents, halogen-based and phosphorus-based flame retardants, other lubricants, and coloring agents. Depending on the performance, it can be appropriately added within a range that does not impair the effects of the present invention.
Hereinafter, the present invention will be described with reference to Examples, but the present invention is not limited to the following Examples.
[0027]
【Example】
A masterbatch was prepared by kneading a modified polyolefin having the composition shown in Table 1 and a polyamide having a melting point lower than that of the polyamide (A) with a usual extruder. This master batch was subjected to Soxhlet extraction with hot xylene for 12 hours, and the extraction residue was dried at 80 ° C. for 24 hours, weighed, and the gel fraction was calculated.
[0028]
Using this master batch, a JIS standard test piece was molded at a cylinder temperature of 290 ° C. with a composition as shown in Table 2, and the physical properties were evaluated.
In addition, using a mold for producing gears, continuous production was performed at a cylinder temperature of 290 ° C. and a mold temperature of 90 ° C. for 6 hours. At that time, the mold deposit adhering to the mold was visually observed. The evaluation was made on four scales: (almost no), Δ (with adhesion), and X (strong adhesion).
[0029]
For the evaluation of the sliding characteristics, a sheet of a JIS standard test piece was cut into a 3 cm square, and evaluated by a ring-on-disk type abrasion tester. The test was performed with a SUS45C two-pin ring at 750 rpm and a load of 20 kg. The amount of wear per hour was calculated from the weight loss of the sample after the test. The modified polyethylene of the present example is an alkoxysilane- modified polyethylene manufactured by Mitsubishi Chemical Corporation, trade name Linklon (grade: HF700N) and maleic anhydride-modified polyethylene, trade name MMHD (grade :) without any special treatment. Using. In particular, with respect to the moisture content of Wrinklon, the moisture content was controlled by leaving it in an atmosphere at 23 ° C. and a humidity of 50% and changing the leaving time.
[0030]
The polyamide resin (A) melt-processable polyamide resin of this example was Toray's polyamide 66 (grade: CM3001N, melting point: 265 ° C.) and used as it was.
The soft nylon used at the time of the production of the master batch was used without any treatment with Nylon 11 (trade name: Rilsan, melting point: 185 ° C.) manufactured by ATO CHEM.
The inorganic filler used in this example was manufactured by Nippon Electric Glass Co., Ltd. using an epoxy sizing agent having a diameter of 10 μm and an average fiber length of 6 mm.
The phosphite used in this example was Irgafos 168 (trade name, manufactured by Ciba Geigy).
[0031]
(Comparative example)
Except that the modified polyolefin of the masterbatch was changed to ordinary unmodified high-density polyethylene (high-density polyethylene manufactured by Mitsubishi Chemical Corporation, trade name: Mitsubishi Polyethylene (grade: JY20, MFR = 9 and HY330B, MFR = 0.6)) The same evaluation as in the example was performed.
[0032]
[Table 1]

[0033]
[Table 2]

Claims (4)

(A) 90 to 50% by weight of a melt-processable polyamide resin;
(B) an alkoxy silane modified polyolefin resin 10-99 wt% and above (A) masterbatch resin 10-50 wt obtained by kneading a polyamide resin 1-90 wt% with polyamide resin and / or melting point lower than that %, And
(C) 0.001 to 5 parts by weight of a phosphite, a phosphate, a phenol-based stabilizer or a sulfur-based heat stabilizer based on 100 parts by weight of the components (A) and (B) in total. A polyamide resin composition comprising: The polyamide resin composition according to claim 1, wherein the insoluble gel of the masterbatch resin after extraction with hot xylene for 12 hours is 10 to 90% by weight. The thermoplastic resin composition according to claim 1, wherein (D) an inorganic filler is added to the components (A), (B), and (C). A sliding member formed by molding the polyamide resin composition according to claim 1.