KR20050006061A - Polyacetal resin-made sliding member - Google Patents

Abstract

PURPOSE: Provided is a sliding component made of polyacetal resin useful in cars, electric/electronic products, office instruments and constructional materials, which shows significantly improved sliding characteristics while maintaining mechanical properties and moldability. CONSTITUTION: The sliding component are formed of a polyacetal resin composition which comprises (A) 100 parts by weight of polyacetal resin, (B) 0.05-20 parts by weight of lubricant oil present in the form of liquid at 200 deg.C, and (C) 1-20 parts by weight of a core/shell polymer comprising a core formed of a rubbery polymer and a glassy shell formed of a vinyl-based copolymer having an oxygen-containing polar group. The polyacetal resin composition has a gloss of 50% or less.

Description

Sliding parts made of polyacetal resin {POLYACETAL RESIN-MADE SLIDING MEMBER}

The present invention relates to a sliding part made of a polyacetal resin composition. More specifically, the present invention relates to a sliding part that maintains inherent excellent mechanical properties, moldability, and the like of the polyacetal resin, and has more excellent sliding characteristics.

Polyacetal resins are widely used as sliding parts in automobiles, electrical and electronic products, office equipment, building materials, etc. because of their balanced physical properties and excellent sliding properties as resins. However, as the use thereof expands, the demand for sliding characteristics also increases, requiring improvement of sliding characteristics and long-term durability thereof.

In order to improve the sliding property according to such a request, there have been attempts to mix various lubricating oils in polyacetal resins. For example, a method of adding a fatty acid ester to a polyacetal resin (for example, see Japanese Patent Publication No. 1978-31900), a method of adding a silicone oil and a silicone gum to a polyacetal resin (for example, Japanese Patent Publication No. 1982-10144) Publication), a method of adding a silicone oil having a viscosity of 150,00 cSt or more to a polyacetal resin (see, for example, Japanese Patent Publication No. 1988-277263), a method of adding a silicone oil and an ester lubricant to a polyacetal resin (See, for example, Japanese Patent Publication No. 1991-69378).

However, since lubricating oils, including silicone oils, are generally very poor in compatibility and affinity with polyacetal resins, it is quite difficult to formulate them, and some amount of addition is required to meet the requirements, but such compositions are prepared. Even if it is possible, the oil easily penetrates to the surface of the resin during molding, and the lubrication action causes slippage between the resins or between the resin and the screw, which causes poor insertion and plasticization of the molding machine. It becomes impossible to process. In addition, the oil easily penetrates into the surface of the molded article, and thus has a disadvantage of lowering the value of the product. Therefore, when adding lubricating oil for the purpose of sliding improvement, it is desired to reduce the addition amount ideally.

Therefore, the addition of a third substance as a retaining material together with lubricating oil for the purpose of improving the said fault is also considered variously. For example, activated carbon, graphite, etc. are mentioned as an inorganic holding material, high molecular weight polyethylene etc. are mentioned as an organic polymer type. However, activated carbon, graphite, and the like have a small ability to adsorb and hold lubricating oil, and high molecular weight polyethylene and the like have insufficient affinity with lubricating oil and have low holding power, and thus practically satisfactory effects have not been obtained. In some cases, the third component may deteriorate the sliding property.

On the other hand, many attempts to mix specific core shell polymers with polyacetal resins have also been studied. A method of adding a core shell polymer having a core of a rubbery polymer and a shell of a glassy polymer and a polyhydric alcohol fatty acid ester to a polyacetal resin (see, for example, Japanese Patent Application Laid-Open No. 1994-100758), and weathering the polyacetal resin A method of adding a core shell polymer having a glassy polymer shell composed of a photo-stabilizing agent, a core of a rubbery polymer and a vinyl copolymer having an oxygen-containing polar group, and an oxyalkylene polymer having 2 to 8 adjacent carbon chains (for example, Japanese Patent Application Laid-Open No. 1994-299047), a method of adding a core shell polymer and a lubricant having a core of a rubbery polymer and a shell of a glassy polymer to a polyacetal resin (for example, Japanese Patent Laid-Open No. 1994-100759) And a core shell polymer and a silicone oil having a core of a rubbery polymer and a shell of a glassy polymer in a high molecular weight polyacetal resin. The method of adding (for example, Unexamined-Japanese-Patent No. 2000-265036) etc. are mentioned.

However, these prior documents are described for the purpose of improving impact resistance, improving fluidity, or improving weather resistance, and are not described for the purpose of improving sliding properties. As such, the conventionally known method cannot obtain a sliding part made of a polyacetal resin composition having good workability and excellent sliding characteristics in the short term or long term, so further improvement is required.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to satisfy such a requirement, the present inventors formed the sliding component from the resin composition which mix | blended the lubricating oil and a specific core shell polymer in polyacetal resin, and the molded article surface of the said sliding component became slippery and slid. The present invention has been completed by discovering that the contact area of the sea is reduced to produce excellent sliding characteristics.

That is, the present invention has (B) 0.05 to 20 parts by weight of lubricating oil having a liquid form at 200 ° C, and (C) a rubber-like polymer and an oxygen-containing polar group based on 100 parts by weight of (A) polyacetal resin. A sliding part made of a polyacetal resin composition obtained by blending 1 to 20 parts by weight of a core shell polymer having a shell of a glassy polymer made of a vinyl copolymer.

Moreover, this invention also provides the goods conveying apparatus in which the center axis | shaft is arrange | positioned in parallel using the use as a sliding part of the said polyacetal resin composition, or many said sliding parts.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the roller shaped article used for the practical characteristic test of an Example.

It is a top view which shows the structure of the test article conveying apparatus which arrange | positioned the rolled article.

3 is a schematic side view showing a situation of a practical property test using a test article transport apparatus.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated concretely. First, the polyacetal resin (A) used in the present invention is a high molecular compound having an oxymethylene group (-CH ₂ O-) as the main structural unit, and contains a small amount of other structural units in addition to the polyacetal homopolymer and the oxymethylene group. It may be any of polyacetal copolymers (including block copolymers), terpolymers, and also molecules may have linear as well as branched crosslinked structures. In addition, two or more kinds of polyacetal resins having different characteristics can be blended and used.

In the present invention, a polyacetal copolymer prepared by copolymerizing a comonomer component of 1 to 30% by weight, particularly 1 to 5% by weight, of such a polyacetal resin is preferable, and thus excellent thermal stability and moldability can be maintained. . It is known that various cyclic ether compounds or cyclic formal compounds can be used as the comonomer component used in the preparation of the polyacetal copolymer. Although not particularly limited, preferred comonomers include, for example, ethylene oxide and 1,3-dioxe. Solene, diethylene glycol formal, 1, 4- butanediol formal, 1, 3- dioxane, a propylene oxide, etc. are mentioned.

Next, the lubricant used as component (B) in the present invention has a liquid form at 200 ° C. That is, it may be in a liquid state or near thereto at about 190 to 220 ° C., which is a temperature used for forming a polyacetal.

Such lubricants used in the present invention are preferably lubricants based on one or two or more selected from the group consisting of silicone oils, polyalkylene glycols, α-olefin oligomers, paraffin oils, alkyl substituted diphenyl ethers and fatty acid esters. In particular, silicone oil-based lubricants, fatty acid ester-based lubricants and α-olefin oligomer-based lubricants are preferred.

Here, as the silicone oil, polydimethylsiloxane, polymethylphenylsiloxane, and the like represented by the structure of the following formula 1 are typically preferably used.

In the above formula, R is a methyl group, but a part thereof may be an alkyl group, a phenyl group, a halogenated alkyl group, a halogenated phenyl group, or the like.

The viscosity of the silicone oil used in the present invention is not particularly limited, but considering the sliding property and its persistence, the dispersibility of the oil in the resin, the workability during melt kneading and molding processing, etc., it is 100 to 100,000 cSt. It is preferable that it is (25 degreeC). In addition, in the present invention, two or more kinds of silicone oils having different structures or viscosities can be mixed and used, and thickeners, solvents and the like can be added to the silicone oil to adjust the viscosity and the like.

The α-olefin oligomer is mainly an aliphatic hydrocarbon having a structure of homopolymerizing C ₆ to C ₂₀ α-olefins or copolymerizing ethylene and C ₃ to C ₂₀ α-olefins. In this invention, the ethylene-alpha-olefin oligomer whose number average molecular weights are 400-4000 is used preferably.

Fatty acid esters are esters of monohydric or polyhydric aliphatic alcohols with monovalent saturated or unsaturated fatty acids or dibasic acids, and those which are preferred for practical use are esters of saturated aliphatic alcohols having 16 or more carbon atoms and saturated fatty acids or polybasic acids having 16 or more carbon atoms. Cetyl alcohol, stearyl alcohol, isostearyl alcohol, behenyl alcohol, erucyl alcohol, hexyl decyl alcohol, octyl dodecyl alcohol, etc. are mentioned as a C16 or more saturated aliphatic alcohol. Examples of the fatty acid having 16 or more carbon atoms include straight or branched chain fatty acids such as palmitic acid, stearic acid, isostearic acid, arachidic acid, behenic acid and montanic acid. Any ester of such monovalent fatty acid and monohydric aliphatic alcohol can be preferably used. Moreover, phthalic acid, adipic acid, sebacic acid, trimellitic acid etc. are mentioned as a dibasic acid which couple | bonds with the said C16 or more aliphatic alcohol and comprises an ester. The ester consisting of such a dibasic acid and an aliphatic alcohol is preferably a full ester in order to maintain the thermal stability of the polyacetal. Among the aliphatic esters composed of such carboxylic acids and alcohols, in terms of price, availability (synthesis and purification), and frictional wear characteristics, stearyl stearate, behenyl behenate, distearyl adipate, and distearyl are particularly preferred. Phthalates and the like. In the present invention, one or two or more selected from these aliphatic esters are preferably used.

In this invention, such (B) lubricating oil is mix | blended in the ratio of 0.05-20 weight part with respect to 100 weight part of (A) polyacetal resins, and shows the effect on the improvement of the friction abrasion characteristic. If the blending amount is less than 0.05 part by weight, the friction coefficient reducing effect is not sufficiently exhibited, and if it is blended in excess of 20 parts by weight, extreme deterioration in moldability and friction characteristics is caused, which is not preferable. Especially preferably, it is 0.5-5 weight part.

Next, the core shell polymer (C) used in the present invention has a shell of a glassy polymer made of a vinyl copolymer having a core of an rubber polymer and an oxygen-containing polar group. Such core shell polymers (C) are generally obtained in a seed emulsion polymerization method by a continuous multi-stage emulsion polymerization method in which the polymer of the previous stage is sequentially covered by the polymer of the subsequent stage.

In the case where the core shell polymer has an intermediate phase as described below, the intermediate phase may be formed by a multi-layer emulsion polymerization method in which a polymer of a later stage penetrates into the polymer of a previous stage. It is preferable to start an emulsion polymerization reaction by adding a monomer, surfactant, and water to a reactor at the time of particle generation polymerization, and then adding a polymerization initiator. First stage polymerization is a reaction to form a rubbery polymer.

As a monomer which comprises the rubbery polymer which is a core of the core shell polymer (C) used by this invention, the alkyl acrylate of C2-C8 of a conjugated diene or an alkyl group, or its mixture is mentioned, for example. These monomers are polymerized to form a rubbery polymer. Examples of such conjugated dienes include butadiene, isoprene and chloroprene. Examples of the alkyl acrylate having 2 to 8 carbon atoms in the alkyl group include ethyl acrylate, propyl acrylate, butyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, and the like. Butyl acrylate is particularly preferably used as the rubbery polymer. In the first stage polymerization, copolymerizable monomers such as conjugated dienes and alkylacrylates, for example, aromatic vinyls such as styrene, vinyltoluene and α-methylstyrene, and vinyl cyanide such as aromatic vinylidene, acrylonitrile and methacrylonitrile And alkyl methacrylates such as vinylidene cyanide, methyl methacrylate and butyl methacrylate.

The shell phase is formed of a glassy polymer made of a vinyl copolymer having an oxygen-containing polar group. Examples of the oxygen-containing polar group include a hydroxyl group, a group having an ether bond (for example, a glycidyl group), an amide group (-CONH-), a nitro group (NO ₂ ), and the like, but particularly a group having a hydroxyl group and an ether bond. desirable. The core shell polymer having no oxygen-containing polar group on the shell has almost no effect of removing gloss, and the sliding property improvement effect of the sliding part made of the polyacetal resin composition, which is the object of the present invention, does not occur.

As a monomer which comprises the vinyl copolymer which has the said oxygen containing polar group, the (meth) acrylate of the alcohol which has two or more oxygen containing polar groups in a molecule | numerator is used, for example. Herein, the alcohol having two or more oxygen-containing polar groups in a molecule refers to an alcohol having one or more oxygen-containing polar groups in addition to the hydroxyl group of the alcohol portion. As the (meth) acrylate of the alcohol having an oxygen-containing polar group, for example, (meth) acrylate of the alcohol having a hydroxyl group and / or a glycidyl group is used. As (meth) acrylate of the alcohol which has a hydroxyl group, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, etc. are mentioned, for example, Preferably, hydroxyethyl (meth) acrylate is used. . As (meth) acrylate of the alcohol which has glycidyl group, glycidyl (meth) acrylate etc. are mentioned, for example, Preferably glycidyl methacrylate is used. In addition, vinyl monomers having an oxygen-containing polar group such as yloxyethanol, allyl glycidyl ether, and the like other than the above-mentioned (meth) acrylate can also be used as constituents of the vinyl copolymer having an oxygen-containing polar group. As a monomer which comprises glassy polymers other than the said monomer which has an oxygen containing polar group, For example, alkyl (meth) acrylates, such as methyl (meth) acrylate, ethyl (meth) acrylate, and butyl (meth) acrylate, styrene, Although vinyl cyanide, such as aromatic vinyls, such as vinyltoluene and (alpha) -methylstyrene, vinyl cyanide, such as aromatic vinylidene, acrylonitrile, and methacrylonitrile, and vinylidene cyanide, is mentioned, Especially preferably, methyl meta Acrylate, styrene, acrylonitrile and the like are used. The shell phase is preferably in the range of 10 to 50% by weight of the entire core shell polymer.

In addition, an intermediate phase may exist between the first stage and the final polymerized phase. For example, a rubbery polymer such as polymerized monomer having a functional group such as glycidyl methacrylate, methacrylic acid, hydroxyethyl methacrylate, polymerized monomer forming a glassy polymer such as methyl methacrylate, butyl acrylate, etc. Seed emulsion polymerization and the like of the polymerization monomer to be formed to form an intermediate phase. These intermediate phases can be selected in various ways depending on the properties of the coreshell polymer required. The structure of the core shell polymer having such an intermediate phase has, for example, a multi-layer structure in which another layer is present between the core and the shell, and a salami structure in which the intermediate layer is dispersed in fine particles in the core. It can be mentioned.

In the present invention, such a (C) core shell polymer is blended in an amount of 1 to 20 parts by weight based on 100 parts by weight of the (A) polyacetal resin, thereby exhibiting an effect on improving the friction wear characteristics by making the surface of the molded article glossless. If it is less than 1 part by weight, the friction coefficient reduction effect is not sufficiently exhibited, and if it is blended over 20 parts by weight, extreme deterioration in moldability and friction characteristics is caused, which is undesirable. Especially preferably, it is 2-10 weight part.

In the present invention, in forming a sliding part from the polyacetal resin composition containing the above constituent components, the polyacetal resin composition preferably has a glossiness of 50% or less, and particularly preferably 30% or less. It has a gloss of, and thus a particularly good sliding effect occurs in the sliding part of the present invention. Such glossiness can be adjusted mainly by the use of the selected core shell polymer as described above and in particular by the addition amount thereof, and is adjusted while taking into account the formulation of the lubricant (B) and the optional components. In addition, glossiness here means what is measured by the measuring method mentioned later.

The polyacetal resin used in the present invention can also be blended with various known additives. For example, various coloring agents, mold release agents, nucleating agents, antistatic agents, other surfactants, various polymers, and the like can be given. In addition, as long as the performance of the molded article aimed at the present invention is not significantly reduced, one or two or more kinds of fillers such as fibrous, plate, and granular powders such as known inorganic, organic, and metals may be mixed and blended. can do. Examples of such fillers include, but are not limited to, glass fibers, glass beads, talc, mica, austenite, carbon fibers, and the like.

The preparation method of the composition of this invention is not specifically limited, It is easily prepared by the well-known equipment and method generally used as a conventional resin composition preparation method. For example, i) a method of mixing each component, followed by extrusion extrusion by means of an extruder to prepare pellets, and ii) preparing pellets having different compositions once, mixing the pellets in a predetermined amount, and forming the pellets. Any method, such as a method of obtaining the molded article of the composition mentioned above, and iii) the method of directly inject | pouring 1 or 2 or more types of each component into a molding machine can be used. In addition, adding a part of the resin component by mixing with other components as a fine particle body is a preferable method in carrying out the uniform compounding of these components.

In addition, the resin composition concerning this invention can be shape | molded by any of extrusion molding, injection molding, compression molding, vacuum molding, blow molding, and foam molding.

The sliding part of the present invention has a cylindrical or cylindrical shape, such as a roller, and has a structure in which the central axis is rotated while being supported in the horizontal direction, and in particular, the article moves on the upper part of the circumferential surface while sliding. In particular, a noticeable effect occurs. Therefore, it is particularly effective to use a plurality of such sliding parts and to arrange their central axes in parallel so as to transfer the article.

Example

Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these.

In addition, in an Example and a comparative example, all "part" shows a weight part. In addition, the method used for evaluation of surface gloss and a friction coefficient in an Example and a comparative example is as follows.

(1) surface glossiness

Gloss in 45 ° -45 ° reflection with digital variable angle glossmeter (SUGA Tester Co., Ltd. UGV-40) in accordance with the glossiness measurement of JIS K7105 using a test piece (70mm × 40mm × 3mm thickness) molded under the following conditions Degrees were measured.

Molding machine; Toshiba Corporation product IS80

(Molding conditions)

Injection pressure: 65MPa

Injection speed: 1m / min

Mold temperature: 85 ℃

(2) friction coefficient

Using the said test piece, it evaluated based on ASTMD-1894. In addition, as a counterpart material, Juracon M90-44 made from Polyplastics Co., Ltd. was used.

(3) practical characteristics

First, a plurality of rolled articles (shaped cylinder body diameter 0.5cm, length 5cm, support portion 0.15cm in diameter and 0.15cm in length) formed in the sock end were molded in the shape shown in FIG.

Next, two plates made of polystyrene having a plurality of support holes having a diameter of 0.20 cm are prepared on the side surfaces, and the support parts of the roller shaped articles are inserted in the support holes, and a plurality of roller shaped articles are arranged in the state of FIG. 2. A test article conveying device was formed. On the other hand, the position of the support hole is adjusted so that the surface of the rolled molded article placed may be above the surface of the plate made of polystyrene.

The conveying apparatus was inclined at an angle of 3 ° as shown in FIG. 3, and the time for which the PET bottle (245 ml: Itoen Oi Ocha) slipped down by a predetermined distance (30 cm) was measured on the main body of the rolled article.

In addition, the abbreviation used by the Example and a comparative example is as follows.

Ethyl acrylate; EA

Methyl methacrylate; MMA

Butyl acrylate; BA

Butadiene; BD

2-ethylhexyl acrylate; EHA

2-hydroxyethyl methacrylate; HEMA

Examples 1 to 13 and Comparative Examples 1 to 13

As shown in Table 1, (A) polyacetal resin (Polyplastics Co., Ltd. product, Juracon M270), (B) various lubricants, (C) rubber-based polymer core and vinyl-based copolymer having an oxygen-containing polar group The core shell polymer (Gantsu Chemical Co., Ltd., P0-0935, core; BA / MMA copolymer, shell; HEMA / MMA) having a shell of glassy polymer was mixed in the ratio shown in Table 1, and then, the Melt kneading to prepare a pellet-like composition. Then, the test piece was produced by injection molding using this pellet, and each evaluation was performed. The results are shown in Table 1.

In addition, the core shell polymer using the composition which does not mix | blend the core shell polymer of (C) component, and the glassy polymer which consists of a vinyl-type copolymer which does not have an oxygen-containing polar group in a shell part as shown in Table 2 (Ganth Chemicals | The composition which mix | blended Note) product, P0-0198, a core, BD / EHA / MMA terpolymer, and a shell; MMA / EA copolymer) was similarly evaluated. The results are shown in Table 2.

B-1; Polydimethylsiloxane (60,000 cSt, manufactured by Tore Dow Corning Silicone, SH-200)

B-2; Polypropylene glycol (580cSt, Sanyo Chemical Co., Ltd., PP3000)

B-3; Poly (ethylene glycol propylene glycol copolymer) (1700cSt, product of Sanyo Chemical Co., Ltd., 50HB-5100)

B-4; α-olefin oligomer (900cSt, product of Mitsui Petrochemical Industries, Lukant HC40)

B-5; α-olefin oligomer (28000cSt, product of Mitsui Petrochemical Industries, Lukant HC600)

B-6; Paraffin Oil (1000cSt, Idemitsu Co., Ltd., Process Oil)

B-7; Alkyl-substituted diphenyl ether (200cSt, Matsumura Petrochemical Research Institute, Moresko High Loop)

B-8; Stearyl stearate

B-9; Distearyl adipate

C-1; Core Shell Polymers (manufactured by Kantsu Chemical Co., Ltd., P0-0935, Core; BA / MMA Copolymer, Shell; HEMA / MMA)

C-2; Core shell polymer (manufactured by Gansu Chemical Co., Ltd., P0-0198, core; BD / EMA / MMA terpolymer, shell; MMA / EA copolymer)

According to the present invention, by blending and molding a polyacetal resin with a lubricating oil and a specific core shell polymer as described above, the molded article surface of the sliding part becomes matt and the contact area during sliding is reduced to obtain excellent sliding characteristics. .

Claims (10)

(A) with respect to 100 parts by weight of a polyacetal resin, (B) 0.05 to 20 parts by weight of a lubricating oil having a liquid form at 200 ° C., and (C) a vinyl copolymer having a core and an oxygen-containing polar group of a rubbery polymer. A sliding component comprising a polyacetal resin composition comprising 1 to 20 parts by weight of a core shell polymer having a shell of a glassy polymer. The method of claim 1, And the polyacetal resin composition has a glossiness of 50% or less. The method of claim 1, And the polyacetal resin composition has a glossiness of 30% or less. The method according to any one of claims 1 to 3, The sliding part of the said lubricating oil (B) is 1 type (s) or 2 or more types chosen from the group which consists of a silicone oil type lubricating oil, a fatty acid ester type lubricating oil, and an alpha-olefin oligomer type lubricating oil. The method according to any one of claims 1 to 3, The sliding part of which the oxygen-containing polar group of the vinyl-type copolymer which comprises the shell of the said core shell polymer (C) is a hydroxyl group and / or a glycidyl group. The method of claim 1, The vinyl copolymer having an oxygen-containing polar group constituting the shell of the core shell polymer (C) is formed by copolymerizing (meth) acrylate of an alcohol having two or more oxygen-containing polar groups as one of the monomer components. Sliding parts. The method of claim 6, The (meth) acrylate of the alcohol which has two or more oxygen containing polar groups in the said molecule | numerator is a hydroxyethyl methacrylate or glycidyl methacrylate. The method of claim 1, A sliding part having a cylindrical or cylindrical shape and having a central axis supported and rotating. An article transport apparatus comprising a plurality of sliding parts according to claim 8, the center axes of which are arranged in parallel. Use as a sliding part of the polyacetal resin composition of any one of Claims 1-3.