JPH05247236A - Sliding material - Google Patents

Abstract

PURPOSE:To obtain a sliding material excellent in slidability and mold release by mixing a specified thermoplastic resin with a specified silane-modified PE resin in a specified ratio. CONSTITUTION:The title material is prepared by mixing 100 pts.wt. thermoplastic resin containing hydrophilic groups (e.g. polycarbonate) with 0.01-20 pts.wt. silane-modified PE resin prepared by grafting an ethylenically unsaturated silane compound (e.g. vinyltrimethoxysilane) onto a PE resin. For reference the figure shows that the sliding material of this invention can retain excellent slidability even after a long-term running.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
Sliding material for the purpose of improving shapeability during product molding, specifically, mold releasability of the product during injection molding, and preventing die head pressure rise during extrusion molding and hollow molding. It is about.

[0002]

2. Description of the Related Art Conventionally, for improving the slidability of resin molded products, there has been blending a base resin with a material having good slidability. Further, to improve the shapeability, there are a method of applying a release agent to an injection molding die, a method of adding an oil component such as silicone oil at the time of injection molding, extrusion molding, or hollow molding. However, a material blend for improving slidability may cause deterioration of the basic physical properties of the base resin, or the effect may not be produced if the amount added is too small, or conversely, interface peeling (hereinafter referred to as delamination) may occur if the amount added is too large. There is. Further, the application of the release agent or the addition of silicone oil or the like may have an adverse effect on the stickiness of the surface of the molded product or the coating or printing on the molded product. An object of the present invention is to solve the above problems and to provide a sliding member having improved slidability.

[0003]

Means for Solving the Problems As a result of intensive investigations based on these circumstances, the present inventors have found a sliding member having improved slidability without affecting the molded product. Was completed. That is, according to the present invention, 100 parts by weight of a thermoplastic resin having a hydrophilic group and 0.01 to 20 parts by weight of a silane-modified polyethylene resin obtained by graft-polymerizing an ethylenically unsaturated silane compound on polyethylene are contained. A sliding member is provided.

The thermoplastic resin having a hydrophilic group as used herein means a hydroxyl group (OH) and a carboxyl group (CO) in the molecule.
OH), amino group (NH ₂ ), ketone group (CO), sulfone group (SO ₃ H), or a resin whose main raw material is a thermoplastic resin having an atom-containing group such as oxygen, nitrogen or sulfur Is. Examples of such a resin include polyamide, polyamideimide, polyarylate, polycarbonate, polyphenylene ether, modified polyphenylene ether, polyimide, liquid crystalline polyester, polyethylene terephthalate, polysulfone, polyether sulfone, polyphenylene sulfide, polybisamide triazole, poly Butylene terephthalate, polyether imide, polyether ether ketone, etc. can be mentioned. These resins can be appropriately selected and used from resins that are usually commercially available.

As the polyethylene used in the silane-modified polyethylene obtained by graft-polymerizing an ethylenically unsaturated silane compound onto polyethylene, a homopolymer of ethylene by a high, medium or low pressure method is used. It is also possible to use a copolymer of the above or a blended mixture thereof. Silane-modified polyethylene is obtained by graft-polymerizing an ethylenically unsaturated silane compound on these polyethylenes in the presence of a radical generator.

The ethylenically unsaturated silane compound used has a general formula: RSiR ' _n Y _3-n (wherein R is an ethylenically unsaturated hydrocarbon or oxyhydrocarbon group, R'is an aliphatic saturated hydrocarbon group). , Y is a hydrolyzable organic group,
n is 0, 1 or 2). Specifically, R is vinyl, acryl, isopropenyl, butenyl, cyclohexenyl, γ- (meth) acryloyloxypropyl, etc., R ′ is methyl, ethyl, propyl, decyl, phenyl, Y is methoxy, ethoxy. , Formyloxy, acetoxy, propionyloxy, alkyl or arylamino and the like, preferably a trialkylsilane in which R is vinyl or γ- (meth) acrylooxypropyl is used.

As the radical generator, any compound capable of generating a free radical site in the polyethylene under the graft reaction condition and having a sufficiently short half-life at the graft reaction temperature can be used. These radical generators are described, for example, in Japanese Examined Patent Publication (Kokoku) No. 48-1711, and typical radical generators include organic peroxides such as dicumyl peroxide, t-butylperoxyoctate, and benzoyl peroxide. And azo compounds such as azoisobutyronitrile and methylazoisobutyrate.

The graft reaction of the ethylenically unsaturated silane compound onto polyethylene is carried out by adding 0.01 to 15 parts by weight of the silane compound to 100 parts by weight of the polyethylene.
Preferably about 0.5 to 10 parts by weight and about 0.01 to 5 parts by weight, preferably about 0.01 to 2 parts by weight of the radical generator are added, and the temperature at which the radical generator used is decomposed, generally 150. It can be performed by kneading at a temperature of from about 200 ° C. As a kneading method, a normal kneading machine such as a single-screw extruder, a twin-screw extruder, a Banbury mixer, a roll, a Brabender plastograph, a kneader can be used. The obtained silane-modified polyethylene is
Those having a density in the range of 0.945 to 0.965 g / cm ³ are preferable. When the density is less than 0.945 g / cm ³ , the heat resistance is poor, and when it is more than 0.965 g / cm ³ , the slidability is deteriorated.

The mixing ratio of the thermoplastic resin having a hydrophilic group and the silane-modified polyethylene resin is 100% by weight of the thermoplastic resin.
The silane-modified polyethylene resin is 0.0 with respect to parts by weight.
The amount is in the range of 1 to 20 parts by weight, preferably 0.05 to 10 parts by weight, and more preferably 0.1 to 5 parts by weight. If the amount of the silane-modified polyethylene resin added is less than 0.01 part by weight, the effect of the present invention is hardly exhibited, and 2
If the amount is more than 0 parts by weight, terami may be generated and rigidity may be decreased.

The flowability of each resin is not particularly limited, but a silane-modified polyethylene resin having good flowability is preferable to a thermoplastic resin having a hydrophilic group under the same temperature condition. The larger the difference in flowability between the two resins, the more preferable. Further, the compatibility of each resin is not required. On the contrary, the case where the compatibility is poor may produce better results, probably because the silane-modified polyethylene resin is likely to appear on the product surface.

The sliding material of the present invention essentially consists of the above-mentioned thermoplastic resin and silane-modified polyethylene resin. Further, in the present invention, these two components are used within the range that the effect of the invention is not significantly impaired. In addition to the above, additional components can be added. As additional components, various fillers such as carbon black, calcium carbonate (heavy, light,
Colloid), talc, mica, silica, alumina, aluminum hydroxide, magnesium hydroxide, barium sulfate, zinc oxide, zeolite, wollastonite, diatomaceous earth, glass fiber, glass beads, bentonite, montmorillonite, asbestos, hollow glass beads , Graphite, molybdenum disulfide, titanium oxide, carbon fiber, aluminum fiber, stainless steel fiber, brass fiber, aluminum powder, wood powder, rice husk and other fillers, as well as thermoplastic resins such as polypropylene, polyethylene (high density, medium Density, low density, linear low density), propylene ethylene block or random copolymer, rubber or latex component such as ethylene / propylene copolymer rubber, styrene / butadiene rubber, styrene / butadiene / styrene block copolymer, Or so Hydrogenated derivatives, polybutadiene, polyisobutylene; thermosetting resins such as epoxy resins, melamine resins, phenol resins, unsaturated polyester resins; antioxidants (phenolic, sulfur-based, etc.), lubricants, organic / inorganic pigments , Ultraviolet absorbers, antistatic agents, dispersants, neutralizing agents, foaming agents, plasticizers, copper damage inhibitors, flame retardants, cross-linking agents, flow improvers and the like.
Among them, in particular, those in which 10 to 70 parts by weight of glass fibers are blended with 100 parts by weight of a thermoplastic resin having a hydrophilic group have a problem that mold releasability is deteriorated. Unexpectedly, releasability is remarkably improved in the composition containing the modified polyethylene resin.

[0012] The thermoplastic resin having a hydrophilic group and the silane-modified polyethylene resin may be added with an additional component, if desired, and used in a conventional single-screw extruder, twin-screw extruder, Banbury mixer, roll, Brabender plastograph, kneader or the like. A kneader can be used for uniform mixing. Normally, each component is kneaded with an extruder or the like to form a pelletized compound, which is then subjected to molding processing.In a special case, each component is directly supplied to the molding machine and kneaded with the molding machine. It is also possible to mold while molding. The sliding material of the present invention can be molded by various molding methods such as injection molding, extrusion molding and blow molding.

The silane-modified polyethylene molded into a product is water-crosslinked in the presence of a silanol condensation catalyst. As the silanol condensation catalyst used here, a compound used as a catalyst for promoting dehydration condensation between silanols of silicone is used. Such silanol condensation catalyst,
Generally, there are carboxylates of metals such as tin, zinc, iron, lead and cobalt, organic bases, inorganic acids, and organic acids. Specifically, for example, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dioctoate. , Stannous acetate,
Carboxylates such as stannous caprylate, lead naphthenate, zinc caprylate and cobalt naphthenate, organic bases such as ethylamine, dibutylamine, hexylamine and pyridine, inorganic acids such as sulfuric acid and hydrochloric acid, toluenesulfonic acid, acetic acid , Organic acids such as stearic acid and maleic acid. The amount of the silanol condensation catalyst used is in the range of about 0.001 to 10 parts by weight, preferably 0.01 to 5 parts by weight, based on 100 parts by weight of the silane-modified polyethylene.

The method for allowing the silanol condensation catalyst to exist is as follows:
For example, the following method can be used. (1) A method of forming a master batch by kneading a silanol condensation catalyst with an extruder or the like to the same polyethylene as used for silane modification, and dry-blending the master batch with silane-modified polyethylene before molding the product. .. (2) A method in which a product containing no silanol catalyst is immersed in an aqueous solution or emulsion of the silanol catalyst. A product in which a silanol condensation catalyst is introduced by these methods also undergoes water-crosslinking due to moisture in the atmosphere when left in the atmosphere, but the product is generally at room temperature to 200 ° C.
For about 10 seconds to 1 week, usually about 1 minute to 1 day, water may be contacted with water (liquid or vapor) at room temperature to about 100 ° C.

[0015]

INDUSTRIAL APPLICABILITY In the sliding material of the present invention, the polyethylene portion of the silane-modified polyethylene resin forms a skin layer at the time of molding, or partially projects on the surface, and after the molding of the product, it is water-crosslinked in the presence of a silanol condensation catalyst. This improves the slidability, and also reduces the frictional resistance with the metal surface of the mold and die during molding, which is also excellent in mold releasability. In addition, since polyethylene is silane-modified, the silane group in the molecule reacts with the hydrophilic group on the other side, and the silane groups react with each other to form a network structure (crosslinking), and the thermoplastic resin having a hydrophilic group and three-dimensional Probably because of forming the entangled structure, the above effect is maintained for a significantly long time.

[0016]

【Example】

Examples 1-6 and Comparative Examples 1-13 As described in Table-1 and Table-2, each component was supplied to the extruder at a predetermined ratio and kneaded to produce a molded product. The obtained molded products were evaluated using the following methods, and the results are shown in Table-1 and Table-2.

The materials used in the examples and comparative examples are as follows. 1. polycarbonate (Mitsubishi Gas Chemical Co., Ltd., trade name "Iupilon") 2. high density polyethylene having a density of 0.952g / cm ³ for the (Mitsubishi Petrochemical Co., Ltd. under the trade name "Mitsubishi polyethylene HD") 100 parts by weight, 1.5 parts by weight of vinyltrimethoxysilane and 0.
Blended with 03 parts by weight of dicumyl peroxide, 220 ° C
A silane-modified product grafted by kneading and extrusion at (density: 0.952 g / cm ³ , MFR: 0.2 g / 10 min). 3. A masterbatch containing 1% by weight of dibutyltin dilaurate for high density polyethylene (trade name "Mitsubishi Polyethylene HD" manufactured by Mitsubishi Petrochemical Co., Ltd.) having a density of 0.952 g / cm ³ . 4. 1.2 parts by weight of maleic anhydride and 100 parts by weight of high-density polyethylene (trade name “Mitsubishi Polyethylene HD” manufactured by Mitsubishi Oil Chemical Co., Ltd.) with a density of 0.965 g / cm ³ and lauroyl for maleic anhydride. A maleic anhydride-modified product (MFR: 2.3 g / 10 min) was prepared by mixing 0.8 mol of peroxide and graft-kneading at 200 ° C. for extrusion. 5. High density polyethylene with a density of 0.958 (trade name "Mitsubishi Polyethylene HD" manufactured by Mitsubishi Petrochemical Co., Ltd.) (MFR: 21 g /
10 min). 6. Glass fiber with an average diameter of 13 μm and an average length of 3 mm.

Experiments and evaluation methods in Examples and Comparative Examples are as follows. 1. Test piece manufacturing method Mold clamping force: 120ton type, clamping method: toggle type, injection capacity (PS): 273g Injection rate: 450cc / sec, maximum injection pressure: 1820kg /
cm ² Using a molding machine having the above specifications, a 100 × 100 × 2 mm sheet and an ASTM bending measurement test piece are molded, and then crosslinked. 2. Cross-linking method The test piece is cross-linked in hot water at 90 ° C for 3 hours. 3. Friction coefficient Ito-type instrumented wear tester manufactured by Tokyo Test Machine Co., Ltd.
Surface pressure P (1.5 kg / cm ² ) × peripheral speed V (18 m / min) = 27 (kg
/ Cm ² · m / min), using chromium-plated steel as the mating material, and measuring at a temperature of 23 ° C and a humidity of 50% 6
The friction coefficient (μ) at the time of running for 0 min (18 m / min × 60 min = 1080 m) was obtained. 4. Flexural modulus According to ASTM D790.

5. Cross-cut peeling test Using a single-edged razor, 11 parallel and 11 vertical and horizontal lines perpendicular to the sheet surface of 100 × 100 × 2 mmt are drawn at 2 mm intervals to make 100 cross-cuts. A cellophane adhesive tape (JISZ1522) was sufficiently pressure-bonded on it, and the surface was kept at about 45 degrees and peeled off at once in front, and the state of the part surrounded by the grids was observed, and the number of peeled grids was recorded. 6. Extrudability 1) Molding machine specifications Screw diameter: φ40, screw shape: full flight screw, L / D: 25, die: See Fig. 1 2) Molding conditions Molding temperature: 270 ° C, die tip temperature: 100 ° C , Screw rotation speed: 30 rpm. Attach the die under the above machine specifications and conditions, and measure the resin pressure at the tip when extruding. 7. Mold release test 1) Molding machine specifications Mold clamping force: 150ton, Mold clamping method: Toggle type, Injection capacity (PS): 273g, Injection rate: 450cc / sec, Maximum injection pressure: 1820kg / cm
² 2) Molding conditions Molding temperature: 300 ℃, Mold temperature: 90 ℃, Injection rate: 15
0cc / sec Increase the injection pressure of the cup-shaped product (6-point pinpoint gate) shown in Fig. 2 and measure the product ejection resistance at that time.

With respect to the samples of Example 5 and Comparative Examples 11 and 12, the continuous test was continued under the same conditions as described above, and the change in the friction coefficient until the running distance of 11 km was obtained. As a result, it was confirmed that the sample of Example 5 retains a remarkably excellent slip property even during long-term running (see FIG. 3).

[0021]

[Table 1]

[0022]

[Table 2]

[Brief description of drawings]

FIG. 1 is an explanatory view showing the shape of a die of an extrusion molding machine used for molding a sliding material of the present invention.

FIG. 2 is an explanatory view showing the shape of a cup-shaped product used in a mold release test in molding a sliding material of the present invention.

FIG. 3 is a graph showing changes in friction coefficient for sliding materials of Example 5 and Comparative Examples 11 and 12.

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display area C10M 107: 32 155: 02) C08L 23:26 C10N 30:06 40:02

Claims (1)

[Claims] 1. A silane-modified polyethylene resin 0.0, wherein 100 parts by weight of a thermoplastic resin having a hydrophilic group and polyethylene are graft-polymerized with an ethylenically unsaturated silane compound.
A sliding member containing 1 to 20 parts by weight.