Surface-treated molded product, method for manufacturing a surface-treated molded product, and article

Abstract

The present invention provides a surface-treated molded product having a polymer layer of sufficient thickness on the surface of a resin molded product containing polyketone, an engineering plastic, which can exhibit various properties, including low friction. [Solution] A surface-treated molded article comprising a molded article made of a resin containing polyketone and a polymer layer containing a polymer provided on the surface of the molded article. The number average molecular weight of the polymer is 100,000 to 3,000,000, the polymer has constituent units derived from monomers such as aromatic vinyl monomers, one end of the polymer is bonded to the polyketone via a bond represented by the following general formula (1), the thickness of the polymer layer is 0.1 to 5 μm, and the polymer occupancy rate σ* on the surface of the molded article is 0.1 or more. TIFF2026147852000010.tif26170 (R1 and R2 represent methyl groups, etc., respectively; "PK" represents polyketone; "PO" represents polymer)

Description

Technical Field

[0001] The present invention relates to a surface-treated molded article, a method for producing a surface-treated molded article, and an article. Background Art

[0002] As a method for modifying a base material, a method is known in which a polymer having a group capable of adsorbing to or reacting with the base material at a terminal thereof is allowed to act on the base material to form a physically or chemically bonded polymer layer on the surface of the base material. A method of forming a polymer layer grafted from the base material surface by polymerizing a monomer starting from a polymerizable group imparted to the base material surface is also known.

[0003] In recent years, so-called "dense polymer brushes" that are grafted at high density onto a substrate using living radical polymerization techniques developed in the 1990s have been researched. In this dense polymer brush, polymer chains are grafted onto the substrate at a high density with an interval of 1 to 4 nm, and the surface occupancy (σ*) is 0.1 or more. Modifying the base material surface with such a dense polymer brush can impart characteristics such as low friction, protein adsorption inhibition, size exclusion properties, hydrophilicity, and water repellency (Patent Documents 1 and 2, Non-Patent Documents 1 to 3). Prior Art Documents Patent Documents

[0004] Patent Document 1 Japanese Unexamined Patent Publication No. 2008-133434 Patent Document 2 Japanese Unexamined Patent Publication No. 2010-261001 Non-Patent Documents

[0005] Non-Patent Document 1 Adv.Polym.Sci.,2006,197,1-45 Non-Patent Document 2 J.Am.Chem.Soc.,2005,127,15843-15847 [Non-Patent Document 3] Polym. Chem., 2012, 3, 148-153 [Overview of the project] [Problems that the invention aims to solve]

[0006] Concentrated polymer brushes (hereinafter also simply referred to as "brushes") possess brushing effects such as high modulus of elasticity, extremely low friction, size exclusion characteristics, and high liquid retention. By using such brushes, it is possible to obtain products with unprecedented performance. In particular, in the fields of tribology, including lubrication, friction, and wear, their extremely low friction allows for energy conservation by reducing frictional energy loss, and is expected to contribute to addressing environmental issues such as carbon dioxide reduction.

[0007] One area where the benefits of low friction are expected is in mechanical parts, and the addition of brushes to mechanical parts is being actively investigated. However, mechanical parts are mainly metal parts such as SUS and ceramic parts such as SiC. On the other hand, from the viewpoint of weight reduction, moldability, and heat resistance, there are fields in which engineering plastic parts are used as mechanical parts. In particular, there is a need to develop high-performance mechanical parts that possess properties such as low friction, sliding properties, and high sealing properties in polyketone components such as polyarylketone, which can be replaced by metal parts with good heat resistance and durability.

[0008] This invention has been made in view of the problems of the prior art, and its objective is to provide a surface-treated molded article having a polymer layer of sufficient thickness on the surface of a molded article made of a resin containing polyketone, which is an engineering plastic, capable of exhibiting various properties including low friction. Furthermore, this invention aims to provide a method for manufacturing the above-mentioned surface-treated molded article, and an article comprising the above-mentioned surface-treated molded article. [Means for solving the problem]

[0009] In other words, the present invention provides the following surface-treated molded product. [1] A surface-treated molded article comprising a molded article made of a resin containing a polyketone, and a polymer layer containing a polymer provided on the surface of the molded article, wherein the number average molecular weight of the polymer is 100,000 to 3,000,000, the polymer has constituent units derived from at least one monomer selected from the group consisting of aromatic vinyl monomers, (meth)acrylate monomers, and (meth)acrylamide monomers, one end of the polymer is bonded to the polyketone via a bond represented by the following general formula (1), the thickness of the polymer layer is 0.1 to 5 μm, and the occupancy rate σ* of the polymer on the surface of the molded article is 0.1 or more.

[0010] TIFF2026147852000001.tif26170 (In the above general formula (1), R1 represents a hydrogen atom, a methyl group, an ethyl group, a phenyl group, or an acyl group, R2 represents a methyl group, an ethyl group, or an acyl group, "PK" represents a polyketone, and "PO" represents a polymer)

[0011] [2] The surface-treated molded article according to [1], wherein the polyketone is polyetheretherketone. [3] The surface-treated molded article according to [1] or [2], wherein the polymer layer is swollen with a good solvent for the polymer, and the thickness of the swollen polymer layer is 1.1 to 3 times the thickness of the polymer layer before swelling.

[0012] Furthermore, the present invention provides a method for manufacturing a surface-treated molded product as described below. [4] A method for producing a surface-treated molded article according to any one of [1] to [3] above, comprising: reacting a reducing agent with a molded article made of a resin containing a polyketone to reduce ketone groups on the surface of the molded article to form hydroxyl groups; reacting the formed hydroxyl groups with a compound represented by the following general formula (2) to introduce polymerization initiators on the surface of the molded article; and polymerizing at least one monomer selected from the group consisting of aromatic vinyl monomers, (meth)acrylate monomers, and (meth)acrylamide monomers in the presence of the molded article on which the polymerization initiators have been introduced to its surface to form a polymer, and providing a polymer layer containing the polymer on the surface of the molded article.

[0013] TIFF2026147852000002.tif25170 (In the above general formula (2), R1 represents a hydrogen atom, a methyl group, an ethyl group, a phenyl group, or an acyl group; R2 represents a methyl group, an ethyl group, or an acyl group; X represents a chlorine atom, a bromine atom, or an iodine atom; and Y represents a chlorine atom or a bromine atom.)

[0014] [5] A method for producing a surface-treated molded article according to [4], wherein the monomer is subjected to surface-initiated living radical polymerization in the presence of the molded article on which the polymerization initiator is introduced on its surface to form the polymer. [6] A method for producing a surface-treated molded article according to [4] or [5], wherein the monomer is surface-initiated polymerized under pressure conditions of 10 to 1,000 MPa to form the polymer. [7] A method for producing a surface-treated molded product according to any one of [4] to [6], wherein the reducing agent is sodium borohydride and the compound represented by general formula (2) is 2-bromo-2-methylpropionic acid bromide.

[0015] Furthermore, the present invention provides the following articles. [8] An article comprising a surface-treated molded product as described in any of [1] to [3] above. [Effects of the Invention]

[0016] According to the present invention, there can be provided a surface-treated molded article in which a polymer layer having a sufficient thickness capable of exhibiting various properties including low friction is provided on the surface of a resin molded article containing polyketone, which is an engineering plastic. Further, according to the present invention, there can be provided a method for producing the above-mentioned surface-treated molded article, and an article including the above-mentioned surface-treated molded article.

[0017] The polymer layer of the surface-treated molded article of the present invention is expected to exhibit durability such as chemical resistance, heat resistance, and solvent resistance in addition to low friction properties. Further, since the base molded article is formed of a resin containing polyketone, which is a plastic, unlike the case of using a base material made of a material such as metal or ceramics, the molded article is lighter in weight and excellent in moldability. Therefore, the surface-treated molded article of the present invention has a high degree of design freedom and can be applied to various uses. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] [Figure 1] It is an electron micrograph showing the cross-sectional microstructure of the surface-treated molded article-1 obtained in Example 1. MODE FOR CARRYING OUT THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments. One embodiment of the surface-treated molded article of the present invention comprises a molded article made of a resin containing polyketone, and a polymer layer containing a polymer provided on the surface of this molded article. The number average molecular weight of the polymer is 100,000 to 3,000,000, and the polymer has a constitutional unit derived from at least one monomer selected from the group consisting of aromatic vinyl monomers, (meth)acrylate monomers, and (meth)acrylamide monomers. One terminal end of the polymer is bonded to the polyketone via a bond represented by the following general formula (1). The thickness of the polymer layer is 0.1 to 5 µm, and the occupancy σ* of the polymer on the surface of the molded article is 0.1 or more. Hereinafter, the surface-treated molded article of the present invention will be described in detail.

[0020] TIFF2026147852000003.tif26170 (In the above general formula (1), R1 represents a hydrogen atom, a methyl group, an ethyl group, a phenyl group, or an acyl group, R2 represents a methyl group, an ethyl group, or an acyl group, "PK" represents a polyketone, and "PO" represents a polymer)

[0021] (molded product) The molded article used as the base material is formed from a resin containing polyketone, and is preferably substantially composed of polyketone. The molded article may also have at least its surface composed of polyketone.

[0022] Polyketones are resins that have a ketone group (-C(=O)-) in their structure. Examples of polyketones include aliphatic polyketones and aromatic polyketones. Examples of aliphatic polyketones include polycarbon ethylene, polycarbon ethylene propylene, and polycarbon propylene. Examples of aromatic polyketones include polyether ketone (PEK) obtained from dihydroxybenzophenone and dichlorobenzophenone; polyether ether ketone (PEEK) obtained from hydroquinone and difluorobenzophenone, etc.; polyether ketone ketone (PEKK) obtained from diphenyl ether and terephthalic acid chloride or isophthalic acid chloride; polyether ether ketone ketone (PEEKK); polyether ketone ether ketone ketone (PEKEKK); copolymers thereof; and polyketones in which halogen atoms, alkyl groups, and alkoxy groups are introduced on the aromatic ring in the monomer units constituting these polyketones.

[0023] The resin constituting the molded product may be a mixture of two or more polyketones, or a mixture of polyketone and engineering plastics such as polyethersulfone. Furthermore, the resin constituting the molded product may be a resin composition containing fillers such as carbon fibers, glass fibers, and carbon nanotubes, or a colored resin colored with pigments. From the viewpoint of heat resistance, mechanical properties, availability, and market versatility, the polyketone is preferably polyetheretherketone (PEEK).

[0024] The shape of the molded product is not particularly limited. Examples of molded product shapes include films, sheets, discs, lenses, tubes, pipes, sticks, fibers, nonwoven fabrics, bottles, gears, and machine parts. For example, molded products manufactured by various molding methods such as injection molding, extrusion molding, blow molding, vacuum forming, rolling molding, foam molding, casting molding, compression molding, T-bed molding, and inflation molding can be used.

[0025] (Polymer layer) The polymer layer is a layer provided on the surface of a molded article, comprising a polymer, and is preferably a layer substantially formed of polymer. The polymer has constituent units derived from at least one monomer selected from the group consisting of aromatic vinyl monomers, (meth)acrylate monomers, and (meth)acrylamide monomers. As the monomers constituting the polymer, (meth)acrylate monomers are preferred because they have a high polymerization rate and mild polymerization conditions. Among these, methacrylate monomers are preferred because they have good living properties and can form polymers with higher molecular weight.

[0026] Examples of aromatic vinyl monomers include styrene, vinyltoluene, vinylhydroxybenzene, chloromethylstyrene, vinylnaphthalene, vinylbiphenyl, vinylethylbenzene, vinyldimethylbenzene, and α-methylstyrene.

[0027] Examples of (meth)acrylate monomers include methyl(meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate, isopropyl(meth)acrylate, butyl(meth)acrylate, 2-methylpropane(meth)acrylate, t-butyl(meth)acrylate, pentyl(meth)acrylate, hexyl(meth)acrylate, octyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, nonyl(meth)acrylate, decyl(meth)acrylate, isodecyl(meth)acrylate, lauryl(meth)acrylate, tetradecyl(meth)acrylate, octadecyl(meth)acrylate, behenyl(meth)acrylate, isostearyl(meth)acrylate, and cycloacrylate. Examples of aliphatic, alicyclic, aromatic alkyl, and alkyl halide (meth)acrylates include alohexyl (meth)acrylate, t-butylcyclohexylmethyl (meth)acrylate, isobolonyl (meth)acrylate, trimethylcyclohexyl (meth)acrylate, cyclodecyl (meth)acrylate, cyclodecylmethyl (meth)acrylate, benzyl (meth)acrylate, t-butylbenzotriazolephenylethyl (meth)acrylate, phenyl (meth)acrylate, naphthyl (meth)acrylate, allyl (meth)acrylate, trifluoroethyl (meth)acrylate, perfluoropentyl (meth)acrylate, and perfluorooctyl (meth)acrylate. (Meth)acrylate monomers may contain hydroxyl groups, glycol groups, acid groups (carboxyl groups, sulfonic acid groups, phosphoric acid groups, etc.), oxygen atoms, amino groups, nitrogen atoms, silicon atoms, etc.

[0028] Examples of (meth)acrylamide monomers include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-hydroxyethyl(meth)acrylamide, and (meth)acryloylmorpholine.

[0029] By selecting and using monomers, it is possible to form polymer layers with functions corresponding to the properties of the resulting polymer. For example, by using fluorine-based monomers, it is possible to form polymer layers that repel water and oil and have low surface tension. Furthermore, by using monomers containing polyethylene glycol groups or carboxyl groups, it is possible to form hydrophilic polymer layers with properties such as anti-fogging. In addition, it is possible to form biocompatible polymer layers that are resistant to the adhesion of proteins and other substances. Moreover, by swelling with lubricating oil, a lubricating film can be formed, resulting in an extremely low-friction polymer layer.

[0030] One end of the polymer constituting the polymer layer is bonded to the polyketone constituting the molded product via a bond represented by the following general formula (1).

[0031] TIFF2026147852000004.tif26170 (In the above general formula (1), R1 represents a hydrogen atom, a methyl group, an ethyl group, a phenyl group, or an acyl group, R2 represents a methyl group, an ethyl group, or an acyl group, "PK" represents a polyketone, and "PO" represents a polymer)

[0032] Examples of structures represented by general formula (1) (excluding the "PK" and "PO" parts) include ethylene carbonyloxy group, 1-propylene carbonyloxy group, acetylmethylene carbonyloxy group, 2-propylene carbonyloxy group, 2-butylene carbonyloxy group, 1-phenyl-1-ethylene carbonyloxy group, and 1-phenyl-1-propylene carbonyloxy group. Among these, the 2-propylene carbonyloxy group derived from 2-bromoisobutyrate bromide is preferred, as it is a compound that can introduce polymerization initiators with mild living radical polymerization conditions and good initiation efficiency.

[0033] The number-average molecular weight (Mn) of the polymer is 100,000 to 3,000,000, preferably 200,000 to 2,000,000. If the Mn of the polymer is less than 100,000, the thickness of the polymer layer will be insufficient, and even if it swells in a liquid medium, the brush effect may not be achieved. On the other hand, polymerizing polymers with an Mn greater than 3,000,000 is difficult, and the molecular weight distribution (PDI) may become excessively large. In this specification, the Mn and Mw of the polymer are values ​​converted to polymethyl methacrylate as measured by gel permeation chromatography (GC).

[0034] The thickness of the polymer layer is 0.1 to 5 μm, preferably 0.3 to 3 μm, and more preferably 0.5 to 1.5 μm. By setting the polymer thickness within the above range (i.e., high film thickness), durability such as abrasion resistance can be improved. If the polymer layer thickness is less than 0.1 μm, abrasion resistance will be insufficient. On the other hand, if the polymer layer thickness exceeds 5 μm, the polymerization time of the polymer becomes excessively long, and it becomes substantially difficult to produce a polymer with a high molecular weight to achieve that thickness.

[0035] The polymer occupancy rate (surface occupancy rate σ*) on the surface of the molded product is 0.1 or higher, preferably 0.1 to 1.0, more preferably 0.15 to 0.8, and particularly preferably 0.2 to 0.7. By keeping the polymer surface occupancy rate σ* within the above range, the properties of a dense polymer brush can be achieved. In other words, by forming a polymer layer with a dense polymer brush polymer, an effective brushing effect is achieved, making it usable in a variety of applications. Furthermore, by reducing frictional energy loss due to extremely low friction and preventing wear, the molded product can be given effects such as extended lifespan, antibacterial and antiviral properties due to size exclusion characteristics, stain resistance, and protein adhesion prevention, as well as high lubricity and high slipperiness due to liquid retention.

[0036] The surface occupancy rate σ* is calculated using the following formula (A): "graft density σ (number of grafts / nm)" 2Using ), it can be calculated according to the following formula (B). σ = dLNAMn ···(A) d: Polymer density L: Polymer layer thickness NA: Avogadro's number Mela: Number average molecular weight of polymers σ*=a 2 σ ···(B) a 2 Monomer cross-sectional area

[0037] The thickness of the polymer layer can be measured using conventionally known methods, such as an ellipsometer, electron microscope, or atomic force microscope. The polymer density can be measured using values ​​described in conventionally known literature or values ​​measured according to methods described in JIS K 7112:1999, etc.

[0038] The variation in polymer layer thickness is preferably within ±20%, and more preferably within ±10%, relative to the average thickness of the polymer layer. The average thickness of the polymer layer is the average value of the polymer layer thickness measured at any 10 locations. If the variation in polymer layer thickness exceeds ±20%, the smoothness of the polymer layer may decrease slightly, resulting in insufficient brushing effect.

[0039] The polymer layer is swollen with a good polymer solvent, and it is preferable that the thickness of the swollen polymer layer be 1.1 to 3 times the thickness of the polymer layer before swelling, in order to exhibit a more effective brushing effect. When the polymer layer is swollen with a good polymer solvent, the polymer chains extend perpendicularly from the surface of the molded product, resulting in a more effective brushing effect. In addition, the good solvent is retained due to the high osmotic pressure, resulting in high liquid retention.

[0040] Suitable solvents (liquid media) for swelling the polymer layer include water-based lubricants and lubricating oils. Examples of water-based lubricants include water, glycerin, polyethylene glycol, and polypropylene glycol. Examples of lubricating oils include hydrocarbon-based lubricants, ester-based lubricants, silicone oils, and ionic liquids. By swelling the polymer layer with these liquid media, brush effects such as extremely low friction, size exclusion characteristics, and high liquid retention can be effectively achieved. This makes it possible to provide various articles with characteristics such as energy saving, long lifespan, and high performance.

[0041] <Method for manufacturing surface-treated molded products> The surface-treated molded product of this embodiment can be manufactured by the method shown below. That is, one embodiment of the method for manufacturing the surface-treated molded product of the present invention is the method for manufacturing the aforementioned surface-treated molded product, and comprises the following steps (1) to (3). Step (1): A step in which a reducing agent is reacted with a molded product made of a resin containing polyketone to reduce the ketone groups on the surface of the molded product and form hydroxyl groups. Step (2): A step in which a compound represented by the following general formula (2) is reacted with the formed hydroxyl group to introduce polymerization initiators to the surface of the molded product. Step (3): In the presence of a molded article on which polymerization initiators have been introduced to its surface, at least one monomer selected from the group consisting of aromatic vinyl monomers, (meth)acrylate monomers, and (meth)acrylamide monomers is polymerized to form a polymer, and a polymer layer containing the polymer is provided on the surface of the molded article.

[0042] TIFF2026147852000005.tif25170 (In the above general formula (2), R1 represents a hydrogen atom, a methyl group, an ethyl group, a phenyl group, or an acyl group; R2 represents a methyl group, an ethyl group, or an acyl group; X represents a chlorine atom, a bromine atom, or an iodine atom; and Y represents a chlorine atom or a bromine atom.)

[0043] (Process (1)) It is known that hydroxyl groups are formed when ketone groups are reduced. Known methods for reducing ketone groups include hydride reduction using lithium aluminum hydride or sodium borohydride; silane reduction using silicon hydride; reduction using tributyltin; catalytic reduction with hydrogen using palladium / carbon; Meerwein-Pondorf-Varley reduction using aluminum alkoxide; and enzymatic reduction. In step (1), a reducing agent is reacted with a molded product made of a resin containing polyketone to reduce the ketone groups on the surface of the molded product and form hydroxyl groups. For example, ketone groups can be easily reduced (hydride reduction) under mild conditions using a reducing agent in an organic solvent. Examples of reducing agents include lithium aluminum hydride, lithium borohydride, sodium borohydride, and borane. Among these, sodium borohydride is preferred as the reducing agent because the reaction is mild and highly safe.

[0044] After dissolving, dispersing, or suspending a reducing agent in an organic solvent, a molded resin product containing polyketone, which is the base material, is immersed in the solvent to reduce the ketone groups on the surface of the molded product and generate hydroxyl groups. As the organic solvent, aprotic polar solvents such as dimethyl sulfoxide (DMSO), tetrahydrofuran (THF), and dimethylformamide (DMF) can be used; or protic polar solvents such as water, methanol, ethanol, and propanol can be used. Preferably, the ketone groups are reduced by heating to 40°C or higher. The generation of hydroxyl groups can be confirmed by analysis such as infrared spectrophotometer or XPS.

[0045] (Process (2)) In step (2), the hydroxyl group formed in step (1) is reacted with a compound represented by the following general formula (2) to introduce polymerization initiators to the surface of the molded product.

[0046] TIFF2026147852000006.tif25170 (In the above general formula (2), R1 represents a hydrogen atom, a methyl group, an ethyl group, a phenyl group, or an acyl group; R2 represents a methyl group, an ethyl group, or an acyl group; X represents a chlorine atom, a bromine atom, or an iodine atom; and Y represents a chlorine atom or a bromine atom.)

[0047] Examples of compounds represented by general formula (2) include acid halogenides such as 2-chloropropionic acid chloride, 2-bromopropionic acid chloride, 2-bromopropionic acid bromide, 2-iodopropionic acid chloride, 2-chloro-2-methylpropionic acid chloride, 2-bromo-2-methylpropionic acid bromide, 2-iodo-2-methylpropionic acid bromide, 3-chloro-3-methylbutanoic acid chloride, 3-bromo-3-methylbutanoic acid bromide, 2-bromo-2-phenylpropionic acid bromide, and 2-acetyl-2-bromopropionic acid bromide. Among these, it is preferable that the compound represented by general formula (2) is 2-bromo-2-methylpropionic acid bromide. 2-Bromo-2-methylpropionic acid bromide is readily available commercially, its bromine atom is easily removed, and the resulting radical is relatively stable because it is a radical on a quaternary carbon, thus suppressing side reactions. Furthermore, it is preferable because the reaction proceeds rapidly at low temperatures.

[0048] A molded product having hydroxyl groups formed on its surface can be brought into contact with and reacted with a compound represented by general formula (2), or a solution obtained by dissolving the compound represented by general formula (2) in an organic solvent, thereby esterifying the hydroxyl groups and introducing polymerization initiators. This reaction is preferably carried out in the presence of a base such as an amine.

[0049] (Step (3)) In step (3), at least one monomer selected from the group consisting of aromatic vinyl monomers, (meth)acrylate monomers, and (meth)acrylamide monomers is polymerized in the presence of the molded article obtained in step (2), which has polymerization initiator groups introduced on its surface, to form a polymer. This provides a polymer layer containing the polymer on the surface of the molded article, thereby obtaining the desired surface-treated molded article.

[0050] Polymerization methods include radical polymerization methods using azo initiators and radical generators such as peroxides. Among these, living radical polymerization is preferred, and surface-initiated living radical polymerization, in which polymerization starts and progresses from the surface, is even more preferred. In general formula (2), halogen atoms such as the chlorine atom represented by X are eliminated as halogen radicals by the action of light, heat, and radicals, generating tertiary or quaternary carbon radicals. The generated tertiary or quaternary carbon radicals attack monomers having groups capable of radical polymerization, reacting and causing the polymer to elongate.

[0051] Examples of living radical polymerization include atom transfer radical polymerization (ATRP), iodine transfer radical polymerization (ITP), reversible transfer catalytic polymerization (RTCP), and reversible coordination-mediated polymerization (RCMP). Among these, ATRP is preferred. ATRP is a living radical polymerization method that utilizes oxidation-reduction catalyzed by a metal complex. Examples of metal catalysts include complexes of copper chloride or copper bromide with polyamines such as dinonyl bipyridine, tridimethylaminoethylamine, and pentamethyldiethylenetriamine; and dichlorotris(triphenylphosphine)ruthenium. ATRP may be bulk polymerization or solution polymerization using organic solvents. Examples of organic solvents include hydrocarbon solvents, ester solvents, glycol solvents, ether solvents, amide solvents, alcohol solvents, sulfoxide solvents, urea solvents, and ionic liquids. In the ATRP method, reducing agents such as tin dilaurate may be used to enhance the reducing properties of the oxidation-reduction reaction, or azo polymerization initiators may be used.

[0052] To stably form high molecular weight polymers with a number-average molecular weight (Mn) of 100,000 to 3,000,000, it is preferable to extend the polymerization time while suppressing termination reactions originating from radical polymerization. Therefore, polymers are formed by polymerizing monomers under pressure (external pressure) conditions of 10 to 1,000 MPa, preferably 100 to 400 MPa. By applying high pressure to the substrate (molded product) and the container holding the monomer during polymerization, the growth rate can be increased while simultaneously reducing the termination reaction rate. This makes it possible to form a polymer of the desired Mn in a shorter time, and to provide a polymer layer of the desired thickness on the surface of the molded product. Note that applying pressures exceeding 1,000 MPa requires special equipment and reaction baths.

[0053] As a polymerization container, it is preferable to use a container that is airtight and can withstand high pressure. Furthermore, since pressure needs to be transmitted inside the container, it is preferable to use a container that has parts that deform under pressure, such as soft or expandable parts made of plastic. Specifically, various containers such as polyethylene bottles, PET bottles, retort pouches, and blister containers can be used. In addition, it is preferable to use a container made of a heat-resistant material that does not easily deform at the polymerization temperature. Furthermore, it is preferable to use a container made of a material that has properties such as chemical resistance and solvent resistance, which makes it resistant to corrosion by polymerization solvents, etc. Examples of materials that make up the polymerization container include polyolefin resins, fluororesins, polyester resins, polyamide resins, and engineering plastics. In addition, it is preferable to prevent gas from entering the polymerization container as much as possible during polymerization. For example, it is preferable to fill the polymerization container with polymerization solution to 90% or more of its capacity.

[0054] It is not easy to verify the molecular weight of the polymers constituting the formed polymer layer. Therefore, it is preferable to perform surface-initiated radical polymerization or surface-initiated living radical polymerization in the presence of an initiator monomer having the same initiator as the polymerization initiator. This forms free polymers that are not included in the polymer layer. Then, by measuring the molecular weight of the formed free polymers according to a standard method, the molecular weight of the polymers constituting the polymer layer can be estimated. As the initiator monomer, for example, compounds such as ethyl 2-bromo-2-methylpropionate can be used. The number-average molecular weight (Mn) of the formed free polymers, measured by GPC in terms of polymethyl methacrylate, is 100,000 to 3,000,000.

[0055] <Goods> One embodiment of the article of the present invention comprises the surface-treated molded article described above. As described above, the surface-treated molded article comprises a polymer layer which is a dense polymer brush of sufficient thickness capable of exhibiting various properties, including low friction. For this reason, the article of this embodiment, which comprises the surface-treated molded article, is suitable for use in, for example, medical equipment, robots, manufacturing equipment, structures, home appliances, vehicles, aircraft, space-related applications, containers, packages, electronic devices, battery materials, display materials, and the like. [Examples]

[0056] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. In the examples and comparative examples, "parts" and "%" are based on mass unless otherwise specified.

[0057] <Manufacturing of surface-treated molded products> (Example 1) A 3cm x 3cm, 1mm thick PEEK plate was prepared as the base material. This base material was immersed in methyl ethyl ketone (MEK), ultrasonically cleaned, and then blow-dried. Next, the base material was placed in a container containing 99.8 parts of dimethyl sulfoxide (DMSO) and 0.2 parts of sodium borohydride, heated at 120°C for 3 hours, then thoroughly washed with methanol, water, dilute hydrochloric acid, and water in that order, rinsed with MEK, and blow-dried. After that, it was dried in a vacuum dryer at 60°C for 3 hours to obtain reduced base material-1.

[0058] A solution was prepared by placing 85.5 parts of toluene, 4.5 parts of pyridine, and 10.0 parts of 2-bromo-2-methylpropionic acid bromide (BBiB) in a glass beaker. Reducing substrate-1 was placed in the beaker and immersed in the solution. It was left at room temperature for 1 hour to introduce the polymerization initiator group, the 2-bromo-2-methylpropyrloyloxy group, onto the surface of the substrate. After thorough washing with toluene and methanol, the substrate was dried to obtain initiator-granting substrate-1.

[0059] Under an argon atmosphere, 0.0005 parts of ethyl 2-bromo-2-methylpropionate (EBiB), 0.043 parts of copper(II) bromide (CuBr2), 0.2610 parts of copper(I) bromide (CuBr), 1.7478 parts of 4,4'-dinonyl-2,2'-bipyridyl (dNbpy), 54.06 parts of methyl methacrylate (MMA), and 56.11 parts of anisole were placed in a glass screw-top tube and stirred to prepare a polymerization solution. The initiator-granting substrate-1 and the polymerization solution were placed in an aluminum laminate bag and heat-sealed while removing the gas. The aluminum laminate bag was placed in a high-pressure apparatus (product name "PV-400", manufactured by Shin Corporation) containing water as the pressurizing medium, and polymerization was carried out at 60°C and 400 MPa for 4 hours. After polymerization, a highly viscous solution containing the formed polymer was generated in the high-pressure apparatus. A portion of the solution was sampled, and the number-average molecular weight (Mn) in terms of polymethyl methacrylate was measured by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as the developing solvent, and the molecular weight distribution (PDI = Mw / Mn) was calculated. The Mn of the formed polymer was 1.89 million, and the PDI was 1.26. The contents removed from the container were thoroughly washed with THF to obtain surface-treated molded product-1, in which a polymer layer was formed on the surface of a substrate (PEEK plate). The thickness of the polymer layer, measured by spectroscopic ellipsometry, was 700 nm. The graft density σ calculated from the above formula (A) was 0.27 strands / nm. 2 The surface occupancy rate σ* calculated from the aforementioned formula (B) was 0.15. Figure 1 shows an electron microscope image of the cross-section of surface-treated molded product-1. As shown in Figure 1, it can be seen that a polymer layer with a thickness of approximately 700 nm is arranged on the surface of the PEEK plate.

[0060] (Examples 2 and 3) Surface-treated molded articles 2 and 3 were obtained in the same manner as in Example 1 described above, except that the types of monomers shown in Table 1 were used. The Mn, PDI, graft density σ, and surface occupancy σ* of the formed polymer, as well as the thickness of the polymer layer, are shown in Table 1. The meaning of the abbreviations in Table 1 is shown below. • PMMA: Polymethyl methacrylate LMA: Lauryl methacrylate PEGMA: Polyethylene glycol monomethyl methacrylate, trade name "Bremmer PME-400", manufactured by NOF Corporation, molecular weight 496) • PLMA: Polylauryl methacrylate PPEGMA: Polyethylene glycol monomethyl ether methacrylate

[0061] (Comparative Example 1) Comparative molded product-1 was obtained in the same manner as in Example 1 described above, except that polymerization was carried out under normal pressure conditions without applying pressure. The Mn, PDI, graft density σ, and surface occupancy σ* of the formed polymer, as well as the thickness of the polymer layer, are shown in Table 1.

[0062] (Comparative Example 2) The substrate (PEEK plate) used in Example 1 was immersed in MEK and ultrasonically cleaned, then blow-dried. A solution was prepared in a glass beaker by adding 85.5 parts toluene, 4.5 parts pyridine, and 10.0 parts BBiB. The substrate was placed in the beaker and immersed in the solution, and left at room temperature for 1 hour to react. After thoroughly washing with toluene and methanol, it was dried. Then, polymerization was carried out in the same manner as in Example 1 to obtain comparative molded product-2. The formed polymer had a Mn of 1.89 million and a PDI of 1.26. Attempts were made to measure the thickness of the polymer layer by spectroscopic ellipsometry, but the presence of the polymer layer could not be confirmed.

[0063] (Comparative Example 3) The substrate (PEEK plate) used in Example 1 was immersed in MEK and ultrasonically cleaned, then blow-dried. Next, the substrate was placed in a container containing 99.8 parts DMSO and 0.2 parts sodium borohydride, heated at 120°C for 3 hours, then thoroughly washed with methanol, water, dilute hydrochloric acid, and water in that order, rinsed with MEK, and blow-dried. After that, it was dried in a vacuum dryer at 60°C for 3 hours to obtain reduced substrate-1. Subsequently, polymerization was carried out in the same manner as in Example 1 to obtain comparative molded product-3. The Mn of the formed polymer was 1.89 million, and the PDI was 1.26. Attempts were made to measure the thickness of the polymer layer by spectroscopic ellipsometry, but the presence of the polymer layer could not be confirmed.

[0064] <Rating> (Measurement of swelling and friction coefficient of polymer layer) Surface-treated molded products-1 to 3 and comparative molded product-1 were each immersed overnight in the types of swelling solvents shown in Table 1 to swell the polymer layers. Subsequently, a ball-on-disk friction and sliding test was performed for 50 cycles using a friction and sliding test machine (product name "TRB3", manufactured by Anton Paar) under conditions of a load of 1N, a sliding radius of 3mm, a sliding speed of 5cm / s, and room temperature, with a 10mm diameter SUJ2 ball as the counter material. The friction coefficients (initial) obtained from data analysis are shown in Table 1. The initial friction coefficient of the polymer layer of surface-treated molded product-1 was 0.013. Thereafter, the friction coefficient gradually increased, finally reaching 0.18.

[0065] (Evaluation of low friction) The low friction properties of the polymer layer were evaluated according to the evaluation criteria shown below. The results are shown in Table 1. ○: The friction coefficient of the polymer layer is 10 -2 That was the order. ×: The friction coefficient of the polymer layer is 10 -1 That was the order.

[0066] TIFF2026147852000007.tif121170 [Industrial applicability]

[0067] The surface-treated molded articles of the present invention are useful as materials applied to the sliding surfaces of sliding members that constitute various devices belonging to, for example, automobiles, medical devices, robots, aerospace, energy, battery components, precision instruments, and the like.

Claims

1. A surface-treated molded article comprising a molded article made of a resin containing polyketone, and a polymer layer containing a polymer provided on the surface of the molded article, The number-average molecular weight of the polymer is 100,000 to 3,000,000. The polymer has constituent units derived from at least one monomer selected from the group consisting of aromatic vinyl monomers, (meth)acrylate monomers, and (meth)acrylamide monomers. One end of the polymer is bonded to the polyketone via a bond represented by the following general formula (1), The thickness of the polymer layer is 0.1 to 5 μm. A surface-treated molded article in which the occupancy rate σ* of the polymer on the surface of the molded article is 0.1 or more. (In the above general formula (1), R １ R represents a hydrogen atom, a methyl group, an ethyl group, a phenyl group, or an acyl group. ２ (wherein indicates a methyl group, ethyl group, or acyl group; "PK" indicates a polyketone; and "PO" indicates a polymer.)

2. The surface-treated molded article according to claim 1, wherein the polyketone is polyetheretherketone.

3. The polymer layer is swollen with a good solvent for the polymer, The surface-treated molded product according to claim 1, wherein the thickness of the swollen polymer layer is 1.1 to 3 times the thickness of the polymer layer before swelling.

4. A method for manufacturing a surface-treated molded product according to any one of claims 1 to 3, A step of reacting a molded product made of a resin containing polyketone with a reducing agent to reduce the ketone groups on the surface of the molded product and form hydroxyl groups, A step of introducing polymerization initiators to the surface of the molded product by reacting the formed hydroxyl group with a compound represented by the following general formula (2), A method for producing a surface-treated molded article, comprising the steps of: polymerizing at least one monomer selected from the group consisting of aromatic vinyl monomers, (meth)acrylate monomers, and (meth)acrylamide monomers in the presence of the molded article on which the polymerization initiator is introduced on its surface to form a polymer; and providing a polymer layer containing the polymer on the surface of the molded article. (In the above general formula (2), R １ R represents a hydrogen atom, a methyl group, an ethyl group, a phenyl group, or an acyl group. ２ (where X represents a methyl group, an ethyl group, or an acyl group; where X represents a chlorine atom, a bromine atom, or an iodine atom; and where Y represents a chlorine atom or a bromine atom.)

5. A method for producing a surface-treated molded article according to claim 4, wherein the monomer is subjected to surface-initiated living radical polymerization in the presence of the molded article on which the polymerization initiator is introduced on its surface to form the polymer.

6. A method for producing a surface-treated molded product according to claim 4, wherein the monomer is surface-initiated polymerized under a pressure of 10 to 1,000 MPa to form the polymer.

7. The reducing agent is sodium borohydride. The method for producing a surface-treated molded article according to claim 4, wherein the compound represented by the general formula (2) is 2-bromo-2-methylpropionic acid bromide.

8. An article comprising a surface-treated molded product according to any one of claims 1 to 3.

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