Surface-modified metal member, method for producing the same, and functional block copolymer

Abstract

To provide a surface-modified metal member that is given arbitrary functions such as hydrophilic properties, hydrophobic properties, etc.SOLUTION: The present invention relates to a surface-modified metal member that has a metal member and a functional block copolymer modifying at least a part of a surface of the metal member, and the functional block copolymer includes: a block (A) which includes a structural unit derived from an acrylic monomer (a) having a functional group capable of reacting with a hydroxyl group; and a block (B) which includes an acryl ester-based monomer (b) having an oxyalkylene group or alkyl group at a side chain.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a surface-modified metal member, a method for manufacturing the same, and a functional block copolymer.

Background Art

[0002] Materials such as stainless steel are excellent in corrosion resistance and are thus widely used in biomaterial applications such as stents. Depending on the application, it is required to modify the surface of materials such as stainless steel. For example, a stainless steel stent may form a thrombus on its surface, which may cause an infarction, and thus modification of its surface characteristics has been desired.

[0003] As a method for modifying a metal surface, for example, Patent Document 1 discloses a surface-modified metal characterized by having at least a part of a surface treated by polymerizing a monomer in the presence of a thermal polymerization initiator.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Materials such as stainless steel have a very stable surface structure, and thus it has not been easy to modify their surfaces. Since the method described in Patent Document 1 performs a polymerization reaction of a monomer on the surface of a metal, it is difficult to apply it to the surfaces of metals having a large area, a complex shape, a closed system, etc., and there has been room for improvement.

[0006] An object of the present invention is to provide a surface-modified metal member having an arbitrary function such as hydrophilicity or hydrophobicity, and a manufacturing method capable of easily manufacturing the surface-modified metal member. Another object of the present invention is to provide a functional block copolymer used for modifying the surface of a metal member.

Means for Solving the Problems

[0007] As a result of intensive studies to solve the above problems, the present inventor has found that the following invention meets the above object, and has reached the present invention.

[0008] That is, the present invention relates to the following inventions. <1> A surface-modified metal member having a metal member and a functional block copolymer that modifies at least a part of the surface of the metal member, wherein the functional block copolymer has a structure derived from an acrylic monomer (a) having a functional group (G) capable of reacting with a hydroxyl group. A block (A) containing a unit and a block (B) containing a structural unit derived from an acrylic ester monomer (b) having an oxyalkylene group or an alkyl group in a side chain. <2> The surface-modified metal member according to <1>, wherein the functional group (G) capable of reacting with the hydroxyl group is a carboxyl group or a glycidyl group. <3> The surface-modified metal member according to <1> or <2>, wherein the acrylic monomer (a) is acrylic acid or methacrylic acid. <4> The surface-modified metal member according to any one of <1> to <3>, wherein the acrylic ester monomer (b) has any functional group selected from the group consisting of a functional group represented by the following formula (I), an unsubstituted alkyl group, and an alkyl group at least partially substituted with fluorine. -(C p H 2p -O) q -R 1 ····(I) (In the formula (I), p is an integer of 1 to 10, q is an integer of 1 to 10, R 1represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms.) <5> The metal member is the surface-modified metal member according to any one of <1> to <4>, including stainless steel.

[0009] <6> A contact step of bringing a metal member with an activated surface into contact with a surface modifier containing a functional block copolymer and a solvent, and a solvent removal step of removing the solvent from the surface of the metal member, wherein the functional block copolymer includes a block (A) containing a structural unit derived from an acrylic monomer (a) having a functional group (G) capable of reacting with a hydroxyl group, and a block (B) containing a structural unit derived from an acrylic ester monomer (b) having an oxyalkylene group or an alkyl group in a side chain. A method for producing a surface-modified metal member. <7> In the solvent removal step, vacuum drying is performed. The method for producing a surface-modified metal member according to <6>. <8> The temperature of the vacuum drying is 100 °C or higher. The method for producing a surface-modified metal member according to <7>. <9> Before the contact step, a surface activation step of activating the surface of the metal member is performed. The method for producing a surface-modified metal member according to any one of <6> to <8>. <10> The surface activation step is a polishing step of polishing the surface of the metal member. The method for producing a surface-modified metal member according to <9>.

[0010] <11> A functional block copolymer for surface modification of a metal member, including a block (A) containing a structural unit derived from an acrylic monomer (a) having a functional group (G) capable of reacting with a hydroxyl group, and a block (B) containing a structural unit derived from an acrylic ester monomer (b) having an oxyalkylene group or an alkyl group in a side chain. <12> A functional block copolymer, including a block (A) containing a structural unit derived from an acrylic monomer (a) having a functional group (G) capable of reacting with a hydroxyl group, and a block (B) containing a structural unit derived from an acrylic ester monomer (b) having an oxyalkylene group in a side chain.

Advantages of the Invention

[0011] According to the present invention, there are provided a surface-modified metal member having an arbitrary function such as hydrophilicity or hydrophobicity, and a manufacturing method capable of easily manufacturing the surface-modified metal member. Further, according to the present invention, there is provided a functional block copolymer used for modifying the surface of a metal member.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Modes for Carrying Out the Invention

[0013] Embodiments of the present invention will be described in detail below. However, the description of the constituent elements described below is an example (representative example) of an embodiment of the present invention, and the present invention is not limited to the following content unless the gist thereof is changed. In the present specification, when the expression "~" is used, it shall be used as an expression including the numerical values or physical property values before and after it.

[0014] <Surface-modified metal member> The present invention relates to a surface-modified metal member having a metal member and a functional block copolymer that modifies at least a part of the surface of the metal member, wherein the functional block copolymer has a structure derived from an acrylic monomer (a) having a functional group (G) capable of reacting with a hydroxyl group. Block (A) containing a unit, and block (B) containing a structural unit derived from an acrylic ester monomer (b) having an oxyalkylene group or an alkyl group in the side chain, and a surface-modified metal member (hereinafter, sometimes referred to as "the member of the present invention").

[0015] A functional block copolymer containing block (A) containing a structural unit derived from an acrylic monomer (a) having a functional group (G) capable of reacting with a hydroxyl group and block (B) containing a structural unit derived from an acrylic ester monomer (b) having an oxyalkylene group or an alkyl group in the side chain is suitable as a surface-modifying resin for modifying the surface of a metal member. By using such a functional block copolymer, the functional block copolymer can be firmly adhered to the surface of the metal member. Further, by adopting a configuration in which the functional block copolymer is modified on the surface of the metal member, it can have excellent durability and functionality due to block (B). Such a member of the present invention can be preferably manufactured by the manufacturing method of the member of the present invention.

[0016] <Method for manufacturing a surface-modified metal member> The present invention relates to a method for producing a surface-modified metal member (hereinafter, may be referred to as "the production method of the present invention"), which has a contact step of bringing a metal member having an activated surface into contact with a surface modifier containing a functional block copolymer and a solvent, wherein the functional block copolymer is a copolymer comprising a block (A) composed of structural units derived from an acrylic monomer (a) having a functional group (G) capable of reacting with a hydroxyl group, and a block (B) composed of structural units derived from an acrylic ester monomer (b) having an oxyalkylene group or an alkyl group in a side chain.

[0017] As a result of a detailed investigation of the surface structure of stainless steel, the present inventors focused on the fact that the passive layer due to oxidation contributes to its stability, newly designed and polymerized a functional block copolymer composed of a unit derived from an acrylic monomer having reactivity with a hydroxyl group on the metal surface and a unit derived from an acrylic monomer exhibiting hydrophilicity. Then, it was found that hydrophilic modification can be achieved by polishing the surface to remove the oxide film and treating the activated stainless steel with a dilute solution of this functional block copolymer. The present invention is based on these findings.

[0018] By using a functional block copolymer comprising a block (A) containing structural units derived from an acrylic monomer (a) having a functional group (G) capable of reacting with a hydroxyl group (sometimes simply referred to as "functional group (G)") and a block (B) containing structural units derived from an acrylic ester monomer (b) having an oxyalkylene group or an alkyl group in a side chain, it is considered that the hydroxyl group (OH group) on the surface of the metal member reacts with the functional group (G) of the block (A) of the functional block copolymer, adsorbs via a chemical bond, and the surface of the metal member is covered at the site of the block (B) (see FIG. 1). Thereby, it is considered that a surface having durability and functionality contributed by the structure of the block (B) can be obtained.

[0019] In addition, it is considered that the functional block copolymer can be effectively adsorbed on the metal member by bringing a surface-activated metal member, on which many hydroxyl groups are exposed on the surface, into contact with a surface modifier containing the functional block copolymer and a solvent.

[0020] Hereinafter, based on FIG. 2, the manufacturing method of the present invention will be described in detail. FIG. 2 is a flowchart showing an example of the manufacturing method of the present invention. As shown in FIG. 2, the manufacturing method of the present invention has a contact step and a solvent removal step.

[0021] [Contact step] The contact step is a step of bringing a metal member with an activated surface into contact with a surface modifier containing a functional block copolymer and a solvent.

[0022] [Surface modifier] In the manufacturing method of the present invention, a surface modifier is used to modify the surface of the metal member. The surface modifier used in the contact step contains a functional block copolymer and a solvent. By using a liquid material containing a solvent, it is easy to arbitrarily adjust the viscosity of the surface modifier and the concentration of the functional block copolymer, and it is easy to impart a desired functionality to a desired range of the metal member.

[0023] In the present application, the surface modifier is a concept including not only a homogeneous solution in which the functional block copolymer is completely dissolved in the solvent, but also a suspension / dispersion liquid. Depending on the structure of the functional block copolymer, it may be difficult to completely dissolve the functional block copolymer in the solvent, so it may be a suspension or dispersion liquid in which the functional block copolymer is dispersed / suspended in the solvent.

[0024] (Functional block copolymer) The functional block copolymer contained in the surface modifier is a copolymer containing a block (A) including a structural unit derived from an acrylic monomer (a) having a functional group capable of reacting with a hydroxyl group, and a block (B) including a structural unit derived from an acrylic ester monomer (b) having an oxyalkylene group or an alkyl group in a side chain. Such a functional block copolymer is suitable for surface modification of a metal member.

[0025] The functional block copolymer may be composed of the block (A) and the block (B), or may further contain other blocks and polymerization sites as long as the object of the present invention is not impaired.

[0026] Here, the "acrylic monomer" means one or more monomers selected from the group consisting of acrylic acid, methacrylic acid, acrylic acid esters, and methacrylic acid esters. The "acrylic ester monomer" means an acrylic acid ester and / or a methacrylic acid ester. Various properties can be introduced into the monomers without impairing the polymerization characteristics of the acrylic monomers and acrylic ester monomers, and there are many commercially available monomer species and they are easily available. Therefore, various properties can be incorporated into the functional block copolymer.

[0027] The functional block copolymer is preferably substantially composed of the block (A) and the block (B). In the functional block copolymer, the total content of the block (A) and the block (B) can be 95% by mass or more, 98% by mass or more, etc. Further, the block copolymer may be any of a diblock copolymer, a triblock copolymer, or the like.

[0028] (Block (A)) The block (A) constituting the functional block copolymer contains a structural unit derived from an acrylic monomer (a) having a functional group (G) capable of reacting with a hydroxyl group. Examples of the functional group (G) capable of reacting with a hydroxy group include a carboxyl group, a glycidyl group, etc., and a carboxyl group is preferable.

[0029] Specific examples of the acrylic monomer (a) include acrylic acid, methacrylic acid, glycidyl acrylate, glycidyl methacrylate, and the like.

[0030] The degree of polymerization of block (A) is preferably 5 to 1,000. If the degree of polymerization of block (A) is too large, there are problems such as difficulty in dispersing and dissolving in the solvent and high viscosity. Also, if the degree of polymerization is too small, the adsorption force of the functional block copolymer to the metal member tends to decrease. The degree of polymerization of block (A) may be 10 or more, 25 or more, or 50 or more. Also, the upper limit may be 750 or less, or 500 or less.

[0031] The molecular weight corresponding to block (A) is preferably 500 to 50,000. If the molecular weight corresponding to block (A) is too large, there are problems such as difficulty in dispersing and dissolving in the solvent and high viscosity. Also, if the molecular weight corresponding to block (A) is too small, the adsorption force of the functional block copolymer to the metal member tends to decrease. The molecular weight of block (A) may be 1,000 or more, 2,000 or more, or 3,000 or more. Also, the upper limit may be 40,000 or less, 25,000 or less, or 10,000 or less.

[0032] These molecular weights are values "Mw: weight average molecular weight" that can be determined in terms of polystyrene conversion from the results obtained by GPC. Also, there may be cases where the functional block copolymer is difficult to dissolve in the solvent and it is difficult to measure the molecular weight. In such cases, the respective molecular weights can be calculated by methods such as elemental analysis, IR, and NMR.

[0033] (Block (B)) Block (B) constituting the functional block copolymer contains a structural unit derived from an acrylic ester monomer (b) having an oxyalkylene group or an alkyl group in the side chain.

[0034] "Oxyalkylene group" The oxyalkylene group is a divalent group represented by "-(C p H 2p -O)-" (where p is an integer of 1 or more). Examples of the functional group having an oxyalkylene group include a group represented by the following general formula (I).

[0035] -(C p H 2p -O) q -R 1 ····(I) (In the general formula (I), p is an integer from 1 to 10, q is an integer from 1 to 10, and R 1 represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms.)

[0036] In the general formula (I), the alkyl group represented by R 1 may be linear or branched, but is preferably linear. Also, it may be unsubstituted or may have a substituent such as a fluorine atom, but an unsubstituted alkyl group is preferred.

[0037] More preferably, in the general formula (I), p is an integer from 1 to 5, q is an integer from 2 to 10, and R 1 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. Even more preferably, p is an integer from 1 to 2, q is an integer from 2 to 10, and R 1 is a hydrogen atom or an alkyl group having 1 to 2 carbon atoms.

[0038] "Alkyl group" The alkyl group in the side chain of the acrylic ester monomer (b) may be linear or branched, but is preferably linear. Also, it may be unsubstituted or may have a substituent such as a fluorine atom.

[0039] The alkyl group in the side chain of the acrylic ester monomer (b) is preferably an unsubstituted alkyl group, or preferably an alkyl group in which at least a part is substituted with fluorine.

[0040] The number of carbon atoms of the unsubstituted alkyl group is preferably 8 or more, more preferably 10 or more, and even more preferably 12 or more. The upper limit thereof can be appropriately set within the range that can be polymerized as a copolymer. As a specific upper limit, realistically, 50 or less carbon atoms is preferable, and 40 or less is more preferable. Also, it may be 30 or less or 25 or less carbon atoms. If the number of carbon atoms of the alkyl group is too large, it may be difficult to form an appropriate three-dimensional structure as a copolymer or to set the polymerization conditions.

[0041] Specific examples of the unsubstituted alkyl group having 8 or more carbon atoms include an octyl group, 2-ethylhexyl group, decyl group, isodecyl group, dodecyl group, isododecyl group, tridecyl group, tetradecyl group, hexadecyl group, octadecyl group (stearyl group), docosyl group (behenyl group), and the like.

[0042] The number of carbon atoms of the alkyl group having at least a part substituted with fluorine is preferably 3 or more, and more preferably 7 or more. The upper limit thereof can be appropriately set within the range that can be polymerized as a copolymer. As a specific upper limit, realistically, it can be 23 or less, 20 or less, or 15 or less carbon atoms.

[0043] The number of fluorine atoms of the alkyl group having at least a part substituted with fluorine can be 3 or more, 5 or more, 10 or more, etc. Also, the upper limit thereof can be 47 or less, 30 or less, 25 or less, 20 or less, etc.

[0044] Examples of the alkyl group having at least a part substituted with fluorine include groups represented by the following general formulas (II-1) to (II-5), and the group represented by general formula (II-1) is preferable.

[0045]

Chemical formula

[0046] Here, in General Formulas (II-1) to (II-5), r is an integer of 1 or more and 14 or less, and s is an integer of 1 or more and 4 or less. Further, X is any selected from the group consisting of H, F, CH2F, CHF2, and CF3.

[0047] The acrylic ester monomer (b) is appropriately selected according to the purpose of modification, and preferably has, in the side chain, any functional group selected from the group consisting of the functional group represented by Formula (I), an unsubstituted alkyl group, and an alkyl group in which at least a part is substituted with fluorine.

[0048] More preferable acrylic ester monomers (b) include the following monomers (b1) to (b3). Monomer (b1): An acrylic ester monomer having a functional group represented by Formula (I) Monomer (b2): An acrylic ester monomer having an unsubstituted alkyl group with 8 or more carbon atoms Monomer (b3): An acrylic ester monomer having a linear alkyl group in which at least a part is substituted with fluorine

[0049] The functional block copolymer containing the block (B) composed of the structural unit derived from the monomer (b1) is a preferable block copolymer for imparting hydrophilicity. Further, the functional block copolymer containing the block (B) composed of the structural unit derived from the monomer (b2) or the monomer (b3) is a preferable block copolymer for imparting hydrophobicity.

[0050] Specific examples of the monomer (b1) include methoxy-polyethylene glycol-acrylate (CH2=CH(CO)O(CH2-CH2-O-) q CH3) (q = 2 to 10), ethoxy-polyethylene glycol-acrylate (CH2=CH(CO)O(CH2-CH2-O-) q C2H5) (q = 2 to 10), polyethylene glycol-monoacrylate (CH2=CH(CO)O(CH2-CH2-O-) qExamples of the monomer include those having an oxyalkylene group such as H)(q = 2 to 10). More specifically, di(ethylene glycol) ethyl ether acrylate (CH2=CH(CO)O(CH2-CH2-O-)2C2H5, Diethylen Glycol Monoethyl Ether Acrylate, DEEA), deca(ethylene glycol) ethyl ether acrylate (CH2=CH(CO)O(CH2-CH2-O-) 10 C2H5), etc.

[0051] Specific examples of the monomer (b2) include dodecyl acrylate (lauryl acrylate), octadecyl acrylate (stearyl acrylate), docosyl acrylate (behenyl acrylate), and the like.

[0052] Specific examples of the monomer (b3) include 1H,1H,2H,2H - heptadecafluorodecyl acrylate (1H,1H,2H,2H - Heptadecafluorodecyl acrylate, HDFA), 2,2,3,3,4,4,5,5,6,6,7,7 - dodecafluoroheptyl acrylate (2,2,3,3,4,4,5,5,6,6,7,7 - Dodecafluorohepthyl Acrylate, DDFA), and the like.

[0053] The degree of polymerization of block (B) is preferably 10 to 500. If the degree of polymerization of block (B) is too large, there are problems such as difficulty in dispersion and dissolution in the solvent and high viscosity. Also, if the degree of polymerization is too small, it is difficult to exhibit the functionality of block (B) and the modification effect tends to decrease. The degree of polymerization of block (B) may be 20 or more, or 30 or more. Also, the upper limit may be 400 or less, or 300 or less.

[0054] The molecular weight corresponding to block (B) is preferably 3,000 to 50,000. If the molecular weight corresponding to block (B) is too large, there are problems such as difficulty in dispersing and dissolving in the solvent and high viscosity. Also, if the molecular weight corresponding to block (B) is too small, there is a problem that it is difficult to exhibit the functionality of block (B) and the modification effect is reduced. The molecular weight of block (B) may be 4,000 or more, 5,000 or more, 6,000 or more. Also, the upper limit may be 40,000 or less, 25,000 or less, 10,000 or less.

[0055] Also, the polymerization ratio of block (A) and block (B) can be block (A) / block (B) = 80 / 20 to 20 / 80, 70 / 30 to 30 / 70, 60 / 40 to 40 / 60, etc.

[0056] Preferred functional block copolymers include, for example, block copolymers of the following general formula (1) and the following general formula (2).

[0057]

Chemical formula

[0058] In general formulas (1) and (2), R a1 and R b1 are each independently a hydrogen atom or a methyl group.

[0059] In general formulas (1) and (2), R b2 is a functional group or an alkyl group represented by the above formula (I). When R b2 is an alkyl group, a preferred embodiment is the same as the alkyl group in the side chain of the above acrylic ester monomer (b).

[0060] In general formulas (1) and (2), m is 5 to 1,000. The preferred range of m is the same as the degree of polymerization of block (A) above. n is 10 to 500. The preferred range of n is the same as the degree of polymerization of block (B) above.

[0061] The functional block copolymer can be obtained by polymerization using known techniques such as various living polymerization methods (radical, anionic, cationic), etc. As the living radical polymerization method, the NMP method, ATRP method, RAFT method, etc. can be used.

[0062] For example, a mixed solution preparation step is performed in which an acrylic monomer (a) is mixed with an initiator in a polymerization solvent to prepare a mixed solution of the acrylic monomer (a). Next, the mixed solution of the acrylic monomer (a) prepared in this mixed solution preparation step is appropriately stirred in a reactor at an appropriate polymerization temperature (for example, about 90 to 120 ° C) under a nitrogen atmosphere or the like, and a monomer (a) polymerization step based on the polymerization mechanism of an initiator such as living radical polymerization is performed to obtain a polymer of the acrylic monomer (a). Further, an acrylic ester monomer (b) is mixed with the solution in which the polymer of the acrylic monomer (a) is mixed, and a monomer (b) polymerization step is performed in which the acrylic ester monomer (b) is further polymerized by radicals or the like in the solution. Thereby, a functional block copolymer containing a block (A) derived from the acrylic monomer (a) and a block (B) derived from the acrylic ester monomer (b) can be obtained. The order of polymerization of the acrylic monomer (a) and the acrylic ester monomer (b) can also be changed according to the monomer species to be polymerized, the molecular weight, and the respective polymerization conditions.

[0063] When other monomers are included, the polymerized monomer may be used as a third monomer for polymerization.

[0064] (Solvent) The solvent contained in the surface modifier only needs to be able to dissolve or disperse the functional block copolymer, and can be appropriately selected according to the structure of the functional block copolymer and the like. Only one type of solvent, or two or more types of solvents can be appropriately mixed and used. Preferably, polar organic solvents such as ethanol, isopropyl alcohol, dimethyl sulfoxide, and N-methylpyrrolidone can be mentioned.

[0065] (Concentration) The concentration of the functional block copolymer in the surface modifier can be appropriately set according to the type of the functional block copolymer, the treatment temperature, the amount of adhesion and the thickness of the adhesion film of the copolymer, the purpose of modification, etc. The concentration of the functional block copolymer in the surface modifier is preferably 0.01 to 2.0% by mass. The lower limit of the concentration of the functional block copolymer is preferably 0.02% by mass or more, more preferably 0.05% by mass or more. When the concentration of the functional block copolymer is too low, the modification effect may be insufficient. The upper limit of the concentration of the block copolymer is preferably 1.5% by mass or less, more preferably 1.0% by mass or less. It can also be 0.8% by mass or less, 0.6% by mass or less, 0.5% by mass or less. Even if the concentration of the functional block copolymer is increased, the modification effect may saturate. Also, when the concentration of the functional block copolymer is too high, micellization may occur due to the self-assembly of the functional block copolymer itself, and the modification effect may not be fully exhibited.

[0066] [Metal member with activated surface] The metal member used in the contact step has an activated surface. Some metal members react with oxygen in the air and their surfaces are covered with an oxide film. In such a state where the surface is covered with an oxide film, it is difficult for the functional block copolymer to adhere, and the modification effect may not be sufficiently obtained, or it may be difficult to stably impart functionality. Therefore, in the contact step of the production method of the present invention, a metal member having an activated surface and having hydroxyl groups present on at least a part of the surface is used.

[0067] Examples of the material of the metal member include iron, iron alloy, aluminum, aluminum alloy, copper, copper alloy, nickel-titanium alloy, titanium, aluminum, tin, zinc-tungsten alloy, etc. Preferably, they are iron, iron alloy, aluminum, aluminum alloy, copper, copper alloy, and more preferably iron or iron alloy. Examples of the iron alloy include stainless steel and carbon steel. Among them, the metal member preferably contains stainless steel, and more preferably is stainless steel.

[0068] Its shape is not particularly limited and can be, for example, plate-shaped, mesh-shaped, wire-shaped, spherical, or a complex shape according to various members.

[0069] In addition, since the metal member used in the present invention only needs to have an active surface when it is brought into contact with the functional block copolymer, a surface activation step for activating the surface can be performed before the contact step, so that even a metal member with an inactive surface can be used. The surface activation step will be described later.

[0070] [Contact Method] The contact method between the metal member and the surface modifier is not particularly limited as long as the surface modifier can be brought into contact with the portion of the metal member to be modified. Examples of the contact method include dip coating, spin coating, applicator coating, slit coating, die coating, bar coating, screen printing, inkjet printing, gravure printing, spray coating, pouring, and the like. Since it is easy to control the surface modifier at a predetermined temperature, one of the preferred contact methods is to immerse the metal member in the surface modifier.

[0071] The temperature (treatment temperature) at which the functional block copolymer and the metal member are brought into contact can be appropriately determined according to the type of the solvent of the surface modifier, the shape of the metal member, the contact time, and the like. The treatment temperature is not particularly limited, and for example, it can be brought into contact at around room temperature of 15°C to 35°C.

[0072] In the contact at the above-mentioned predetermined temperature, the surface modifier may be set to the predetermined temperature in advance and then brought into contact with the metal member. Alternatively, the metal member may be brought into contact with the surface modifier at around room temperature and then heated to raise the temperature to the predetermined temperature. Further, the surface modifier may be quickly removed after the contact at the predetermined temperature, or the surface modifier and the metal member may be cooled or gradually cooled while being in contact.

[0073] The treatment time for bringing the surface modifier into contact with the metal member can be appropriately determined according to the contact method, the composition of the surface modifier, the shape of the metal member, etc. For example, when performing the process in a state where the reactivity between the functional block copolymer and the metal member is enhanced, such as by increasing the treatment temperature, the treatment time may be relatively short, such as 1 second or more, 10 seconds or more, or 30 seconds or more. Also, the treatment time may be 1 minute or more, or 5 minutes or more. The treatment time may be long, such as 60 minutes or less or 40 minutes or less. Also, since the modification effect saturates when the contact between the functional block copolymer and the metal member is for a certain period of time or more, it may be 30 minutes or less or 20 minutes or less according to conditions such as the treatment temperature.

[0074] [Solvent removal step] The solvent removal step is a step performed after the contact step and is a step of removing the solvent from the surface of the metal member. The solvent removal may be performed by a conventionally known method, and may be dried at around room temperature in a well-ventilated environment, or may be dried in a reduced-pressure or heated environment as appropriate. Among these, it is preferable to perform vacuum drying in the solvent removal step. Thereby, the equilibrium tends in the direction that the hydroxyl groups on the surface of the metal member react with the functional groups of block (A) of the functional block copolymer to form bonds, and it is considered that the adsorption becomes stronger.

[0075] Vacuum drying can be performed by a conventionally known method. Vacuum drying may be performed at room temperature or while heating, but it is preferable to perform it while heating. The temperature of vacuum drying is not particularly limited as long as it is lower than the decomposition temperature of the functional block copolymer. In order to efficiently adsorb the functional block copolymer on the surface of the metal member, the temperature of vacuum drying is preferably 40°C or higher, and more preferably higher in the order of 60°C or higher, 80°C or higher, 100°C or higher, 120°C or higher. Also, since the effect of promoting the adsorption of the functional block copolymer saturates at a certain temperature or higher, the upper limit may be set, such as 200°C or lower, 180°C or lower, 160°C or lower.

[0076] The vacuum drying time can be, for example, 10 minutes or more, 20 minutes or more, 30 minutes or more, etc. The vacuum drying time can be appropriately determined according to the temperature of vacuum drying, etc. However, if the vacuum drying time is too short, the modification effect may be insufficient. Also, the vacuum drying time can be 120 minutes or less, 60 minutes or less, etc.

[0077] Figure 3 is a flowchart showing another example of the manufacturing method of the present invention. The manufacturing method of the present invention shown in Figure 3 performs a contact step after performing a surface activation step of activating the surface of a metal member. Thereby, even a metal member with an inactive surface can be used. Also, for the purpose of improving the adhesiveness of the functional block copolymer, a surface activation step may be performed on a metal member having an active surface.

[0078] [Surface activation step] The surface activation step is a step of activating the surface of a metal member. For example, it can be a step of removing at least a part of the oxide film formed on the surface of the metal member. Thereby, a metal member having a surface where the surface is activated and at least a part of the hydroxyl groups are exposed is obtained. The surface activation of the metal member may be to activate the entire surface (remove the oxide film), or may be to activate only the surface of the part to be modified. The method of surface activation is not particularly limited. As the method of surface activation, for example, it may be a step of polishing the surface of the metal member. In polishing, it is only necessary to be able to polish the part of the metal member to be modified. The entire surface of the metal member may be polished, or only the part to be modified may be polished. As the polishing method, any method such as sandpaper, blast polishing, barrel polishing, or vibratory finishing can be used.

[0079] [Surface-modified metal member] As described above, the member of the present invention has a metal member and a functional block copolymer that modifies at least a part of the surface of the metal member. In the member of the present invention, the metal member and the functional block copolymer are bonded by a chemical bond between at least a part of the functional group (G) of the block (A) of the functional block copolymer and the surface of the metal member. The functional block copolymer constituting the member of the present invention is the same as the functional block copolymer contained in the surface modifier used in the production method of the present invention described above, except that at least a part of the functional group (G) of the block (A) forms a chemical bond with the surface of the metal member, and the preferred embodiments are also the same.

[0080] The chemical bond formed between at least a part of the functional group (G) of the block (A) of the functional block copolymer and the surface of the metal member is a bond formed by the reaction of the functional group (G) of the block (A) of the functional block copolymer and the OH group on the surface of the metal member. Depending on the structure of the functional group (G), for example, it can be bonded via an ester bond or an ether bond.

[0081] In addition, the fact that the surface of the metal member is surface-modified with the functional block copolymer can be confirmed by analyzing the infrared absorption spectrum (FTIR) and the components of the surface of the surface-modified metal member by EDX analysis or the like. For example, the surface of the surface-modified metal member of the present invention has an absorption peak derived from C=O in the range of 1600 to 1800 cm -1 and can have an absorption peak derived from OH in the range of 2500 to 3100 cm -1 .

[0082] For example, the member of the present invention can have a metal member and a functional block copolymer containing a block (A) containing a structural unit derived from acrylic acid or methacrylic acid that modifies at least a part of the surface of the metal member and a block (B). At this time, a part of the carboxyl group of the block (A) of the functional block copolymer forms an ester bond with the OH group on the surface of the metal member, whereby the functional block copolymer is fixed to the surface of the metal member.

[0083] Further, when a functional block copolymer containing block (A) and block (B) and including a structural unit derived from an acrylic monomer (a) having a glycidyl group is used to form a substrate on the surface of a metal member, a part of the glycidyl groups of block (A) of the functional block copolymer reacts with the OH groups on the surface of the metal member to form an ether bond, thereby adhering to the surface of the metal member.

[0084] The member of the present invention is a surface-modified metal member modified with a functional block copolymer containing block (B) including a structural unit derived from an acrylic ester monomer (b) having an oxyalkylene group in the side chain, so that it can have a hydrophilic surface. Specifically, the contact angle of the surface modified with the functional block copolymer can be 70 degrees or less or 60 degrees or less.

[0085] Further, by using a surface-modified metal member modified with a functional block copolymer containing block (B) including a structural unit derived from an acrylic ester monomer (b) having an oxyalkylene group in the side chain, it can be expected to impart antithrombogenicity. Therefore, it can be suitably used for biomaterial applications such as stents.

[0086] Further, by using a surface-modified metal member modified with a functional block copolymer containing block (B) including a structural unit derived from an acrylic ester monomer (b) having a linear alkyl group with 8 or more carbon atoms without substitution or a linear alkyl group having at least a part substituted with fluorine in the side chain, it can have a hydrophobic surface.

Examples

[0087] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless the gist thereof is changed.

[0088] <Synthesis of Functional Block Copolymer (FBC)> [Reagents] As the acrylic monomer (a), 2-2 (ethoxyethoxy) ethyl acrylate (DEEA) was used, and as the acrylic ester monomer (b), acrylic acid (AA) was used. Bloc Builder (registered trademark) MA (manufactured by Arkema) was used as the polymerization initiator. Butyl acetate was used as the solvent.

[0089] [Manufacturing] According to the polymerization scheme shown in Fig. 4, 2-2 (ethoxyethoxy) ethyl acrylate and acrylic acid were polymerized by living radical polymerization (NMP method) to obtain FBC(1) (AA-DEEA).

[0090] The FTIR spectrum of the obtained FBC(1) was measured. For the measurement of the IR spectrum, Spectrum Two (manufactured by PerkinElmer Japan Co., Ltd.) was used. As shown in Fig. 5, in the FTIR spectrum of FBC(1), peaks of C=O stretching vibration of ester, C=O stretching vibration of carboxylic acid, and O-H stretching vibration of carboxylic acid were observed, while the absorption peak of C=C (vinyl bond) stretching vibration was not observed. Also, since the peaks of FBC(1) and AA:DEEA = 1:1 (2500~3100 cm -1 ) are similar, the polymerization ratio (m:n) is considered to be approximately 1:1.

[0091] [Surface Modification of Stainless Steel Plate] [Comparative Example 1]: Pretreatment of Stainless Steel Plate As the metal member, a stainless steel plate (0.5×25×100 mm) manufactured by Goku Ten Co., Ltd. was used. The immersion of the stainless steel plate in toluene and wiping were repeated 3 times. Then, the stainless steel plate was immersed in acetone overnight, taken out, wiped with Kimwipe (registered trademark), and air-dried. This was used as an untreated stainless steel plate without surface activation treatment.

[0092] [Comparative Example 2]: Surface Modification of Untreated Stainless Steel Plate 1) A 0.1 wt% ethanol solution of FBC(1) was prepared and used as the modification solution (1). 2) The untreated stainless steel plate of Comparative Example 1 was immersed in the modified solution (1) at room temperature for 10 minutes. 3) The untreated stainless steel plate was taken out from the modified solution (1) and dried in a vacuum dryer at 200 °C for 30 minutes. 4) It was wiped 5 times with a Kimwipe (registered trademark) containing ethanol and air-dried for one day.

[0093] [Comparative Example 3]: Pretreatment of Stainless Steel Plate (Surface Activation Step) As the metal member, a stainless steel plate (0.5 × 25 × 100 mm) manufactured by Goku-Ten Co., Ltd. was used, and the immersion in toluene and wiping were repeated 3 times. Next, the stainless steel plate was immersed in acetone overnight, taken out, wiped with a Kimwipe (registered trademark), and air-dried. Further, in order to destabilize the passive state formed on the stainless steel plate and increase the surface area, one side was polished in a lattice pattern with waterproof paper #2000, 3 minutes each vertically and horizontally. It was washed with water and acetone and air-dried. This was used as a polished stainless steel plate subjected to surface activation treatment.

[0094] [Example 1]: Surface Modification of Polished Stainless Steel Plate Instead of the untreated stainless steel plate of Comparative Example 1, the polished stainless steel plate of Comparative Example 3 was used, and the surface-modified stainless steel plate of Example 1 was obtained in the same manner as in Comparative Example 2 except that the temperature of vacuum drying was 15 °C.

[0095] [Examples 2 to 7] Surface-modified stainless steel plates of Examples 2 to 7 were obtained in the same manner as in Example 1 except that the drying temperature of vacuum drying was the temperature shown in Table 1.

[0096]

Table 1

[0097] <Evaluation of Surface-Modified Stainless Steel Plate> [FTIR-1 of Surface-Modified Stainless Steel Plate] The FTIR spectra of Comparative Example 2 (untreated stainless steel plate, drying temperature 200°C) and Example 7 (polished stainless steel plate, drying temperature 200°C) were measured. For the measurement of the IR spectrum, Spectrum Two (manufactured by PerkinElmer Japan Co., Ltd.) was used. As shown in Fig. 6, it can be seen that FBC(1) remains well on the polished stainless steel plate.

[0098] [FTIR-2 of Surface-Modified Stainless Steel Plate] The FTIR spectra of Examples 1 to 7 (polished stainless steel plates, drying temperatures 15°C to 200°C) were measured. For the measurement of the IR spectrum, Spectrum Two (manufactured by PerkinElmer Japan Co., Ltd.) was used. As shown in Fig. 7, peaks appear strongly at 100°C or higher, and it can be seen that more FBC(1) remains on the surface.

[0099] [SEM-EDX of Surface-Modified Stainless Steel Plate] Using SEM (Microscope (registered trademark) TM4000Plus (manufactured by Hitachi High-Technologies Corporation)) and EDS (QUANTAX 75 (manufactured by Bruker)), surface observation and EDX mapping were performed on Example 4 (polished stainless steel plate, drying temperature 100°C) and the unmodified polished stainless steel plate. Fig. 8 shows the results of the SEM image, EDX mapping, and EDX spectrum of Example 4, and Fig. 9 shows the results of the SEM image, EDX mapping, and EDX spectrum of the unmodified polished stainless steel plate. Comparing the EDX mappings in Figs. 8 and 9, the area of yellow indicating carbon (C) in Example 4 shown in Fig. 8 was larger, and the areas of light blue indicating iron (Fe) and blue indicating nickel (Ni) were smaller than those of the unmodified polished stainless steel plate shown in Fig. 9. It was also confirmed from the elemental analysis by EDX that FBC(1) was present on the stainless steel plate.

[0100] [Contact Angle of Surface-Modified Stainless Steel Plate] The contact angles of the untreated and unmodified stainless steel plate of Comparative Example 1, the polished stainless steel plate of Comparative Example 3, and the surface-modified stainless steel plates of Examples 1 to 7 were measured. The results are shown in Table 2. As shown in Table 2, it can be seen that by treating with FBC(1), the contact angle decreases overall and the surface has been modified.

[0101]

Table 2

Industrial Applicability

[0102] According to the present invention, the properties of the surface of metal members used in various fields can be easily modified, leading to performance improvement and enabling utilization in new applications, thus being industrially useful.

Claims

1. A surface-modified metal member having a metal member and a functional block copolymer that modifies at least a part of the surface of the metal member, The functional block copolymer includes a block (A) composed of structural units derived from an acrylic monomer (a) having a functional group (G) capable of reacting with a hydroxyl group, and a block (B) composed of structural units derived from an acrylic ester monomer (b) having an oxyalkylene group or an alkyl group in a side chain, The acrylic ester monomer (b) has, in a side chain, any functional group selected from the group consisting of a functional group represented by the following formula (I), an unsubstituted alkyl group having 8 or more carbon atoms, and an alkyl group in which at least a part is substituted with fluorine. A surface-modified metal member. -(C p H 2p -O) q -R 1 ····(I) (In formula (I), p represents an integer of 1 to 10, q represents an integer of 1 to 10, and R 1 represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms.)

2. The surface-modified metal member according to claim 1, wherein the functional group (G) capable of reacting with the hydroxyl group is a carboxyl group or a glycidyl group.

3. The surface-modified metal member according to claim 1 or 2, wherein the acrylic monomer (a) is acrylic acid or methacrylic acid.

4. In the functional block copolymer, the total content of the block (A) and the block (B) is 95% by mass or more. The surface-modified metal member according to any one of claims 1 to 3.

5. The surface-modified metal member according to any one of claims 1 to 4, wherein the metal member contains stainless steel.

6. It includes a block (A) composed of structural units derived from an acrylic monomer (a) having a functional group (G) capable of reacting with a hydroxyl group, and a block (B) composed of structural units derived from an acrylic ester monomer (b) having an oxyalkylene group or an alkyl group in a side chain, The functional block copolymer for surface modification of a metal member, wherein the acrylic ester monomer (b) has, in a side chain, any functional group selected from the group consisting of a functional group represented by the following formula (I), an unsubstituted alkyl group having 8 or more carbon atoms, and an alkyl group in which at least a part is substituted with fluorine. -(C p H 2p -O) q -R 1 ····(I) (In the formula (I), p is an integer of 1 to 10, q is an integer of 1 to 10, and R 1 represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms.)

7. A contact step of bringing a metal member having an activated surface into contact with a surface modifier containing a functional block copolymer and a solvent, A solvent removal step of removing the solvent from the surface of the metal member, and having, The method for producing a surface-modified metal member, wherein the functional block copolymer is the functional block copolymer for surface modification of a metal member according to claim 6.

8. The method for producing a surface-modified metal member according to claim 7, wherein vacuum drying is performed in the solvent removal step.

9. The method for producing a surface-modified metal member according to claim 8, wherein the temperature of the vacuum drying is 100°C or higher.

10. Before the contact step, a surface activation step of activating the surface of the metal member is performed, and the method for producing a surface-modified metal member according to any one of claims 7 to 9.

11. The method for producing a surface-modified metal member according to claim 10, wherein the surface activation step is a polishing step of polishing the surface of the metal member.

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