JP5763563B2 - Surface modification method and surface modified elastic body - Google Patents

Description

The present invention relates to a surface modification method, a gasket for a syringe having at least a part of a modified surface obtained by the modification method, and a surface modification elasticity such as a tire having at least a part of a tire groove surface. About the body.

For parts that slide while maintaining a sealed state, for example, gaskets that are integrated with the plunger of a syringe and seal the plunger and syringe, the sealing property is emphasized, and an elastic body such as rubber is used. However, there is a slight problem in slidability (see Patent Document 1). For this reason, a sliding property improving agent such as silicone oil is applied to the sliding surface, but it has been pointed out that silicone oil may adversely affect biopharmaceuticals that have recently been put on the market. On the other hand, gaskets not coated with a slidability improver are inferior in slidability, causing pulsation without smoothly pushing the plunger during administration, resulting in inaccurate injection volume, causing pain to patients, etc. Problem arises.

In order to satisfy such contradictory requirements of sealability and slidability, a technique for coating a self-lubricating PTFE film has been proposed (see Patent Document 2). The manufacturing cost increases and the application range is limited. In addition, there is a concern about reliability when a product coated with a PTFE film is applied to an application in which durability is required due to repeated sliding and the like. Furthermore, since PTFE is vulnerable to radiation, there is also a problem that sterilization by radiation cannot be performed.

In addition, application to other uses that require slidability in the presence of water is also conceivable. That is, water can be sent without loss by lowering the fluid resistance of the syringe inner surface of the prefilled syringe and the inner surface of the tube or tube for feeding water, increasing the contact angle with water, or reducing it significantly. By reducing the fluid resistance on the groove surface of the tire, increasing the contact angle with water, or reducing it significantly, water and snow on wet and snowy road surfaces will be better, resulting in improved grip and hydroplaning. And safety is improved. It can also be expected that dust and dust are less likely to adhere by reducing the sliding resistance of the tire sidewall and building walls and increasing the contact angle with water.

Furthermore, pressure loss when water or an aqueous solution is sent by a diaphragm such as a diaphragm pump or a diaphragm valve is reduced. It becomes easy to slip by improving the slidability of the sliding surface of the ski or snowboard. Signs are easier to see by improving the slidability of road signs and billboards and making the snow more slippery. By reducing the sliding resistance of the outer peripheral surface of the ship or increasing the contact angle with water, the resistance of water is reduced and bacteria are less likely to adhere to the outer peripheral surface. It is also possible to expect advantageous effects such as reducing the water resistance by improving the sliding property of the yarn surface of the swimsuit.

JP 2004-298220 A JP 2010-142537 A

The present invention solves the above-mentioned problems, provides a superior slidability and durability against repeated sliding without using an expensive self-lubricating resin, and can also maintain a sealing property. It is an object of the present invention to provide a surface modification method for rubber or thermoplastic elastomer. Another object of the present invention is to provide a surface modified elastic body such as a gasket for a syringe having at least a part of a modified surface obtained by the surface modification method, a tire having at least a part of a groove surface of a tire. To do.

The present invention is a surface modification method using a vulcanized rubber or a thermoplastic elastomer as a modification target, wherein the surface of the modification target is irradiated with 300 to 400 nm LED light, and the light enhancement on the surface is performed. Step 1 of forming a polymerization starting point from a sensitizer and starting from the polymerization starting point, radical polymerization monomer is irradiated with 300 nm to 400 nm LED light for radical polymerization, and a polymer is formed on the surface of the modification target And a step 2 of growing a chain.

In the step 2, the radical polymerization monomer to which a reducing agent or an antioxidant is added is radically polymerized by irradiating 300 to 400 nm LED light starting from the polymerization starting point, and the surface of the modification target It is preferable that the step of growing a polymer chain.

The vulcanized rubber or thermoplastic elastomer preferably has an allylic carbon atom that is a carbon atom adjacent to the double bond.

（式（１）中、Ｒ^１〜Ｒ^５及びＲ^１′〜Ｒ^５′は、同一若しくは異なって、水素原子、アルキル基、ハロゲン、水酸基、１〜３級アミノ基、メルカプト基、又は酸素原子、窒素原子若しくは硫黄原子を含んでもよい炭化水素基を表し、隣り合う任意の２つが互いに連結し、それらが結合している炭素原子と共に環構造を形成してもよい。） As the photosensitizer, a benzophenone compound represented by the following formula (1) is preferably used.

(In formula (1), R ^{1 to} R ⁵ and R ¹ ′ to R ⁵ ′ are the same or different and are a hydrogen atom, an alkyl group, a halogen, a hydroxyl group, a ^primary to tertiary amino group, a mercapto group, or an oxygen atom. Represents a hydrocarbon group which may contain a nitrogen atom or a sulfur atom, and any two adjacent groups may be connected to each other to form a ring structure together with the carbon atom to which they are bonded.)

As the reducing agent or antioxidant, it is preferable to use at least one selected from the group consisting of riboflavin, ascorbic acid, α-tocopherol, β-carotene and uric acid.

In the surface modification method, it is preferable that an inert gas is introduced into the reaction vessel and the reaction liquid at the time of irradiation of the LED light or before irradiation, and the polymerization is performed by substituting the inert gas atmosphere.

As the radical polymerizable monomer, a fluoro group-containing monomer is preferably used. Here, as the fluoro group-containing monomer, a fluoroalkyl group-containing monomer can be suitably used.

Examples of the fluoroalkyl group-containing monomer include 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,12. _{-heneicosafluorododecyl acrylate (H 2 C = CHCO} 2 CH 2 CH 2 (CF 2) 9 CF 3), 3,3,4,4,5,5,6,6,7,7,8,8,9,9 _{, 10,10,10-Heptadecafluorodecyl acrylate (H 2} C = CHCO 2 CH 2 CH 2 (CF 2) 7 CF 3), 3- (perfluorobutyl) -2-hydroxypropyl acrylate (F (CF 2) 4 CH 2 CH ( _{OH) CH 2 OCOCH = CH 2} ), 3-perfluorohexyl-2-hydroxy _{ropyl acrylate (F (CF 2)} 6 CH 2 CH (OH) CH 2 OCOCH = CH 2), 3- (perfluoro-3-methylbutyl) -2-hydroxypropyl acrylate ((CF 3) 2 CF (CF 2) 2 CH _{2 CH (OH) CH 2 OCOCH} = CH 2), and 3- (perfluoro-5-methylhexyl) -2-hydroxypropyl acrylate ((CF 3) 2 CF (CF 2) 4 CH 2 CH (OH) CH 2 OCOCH = At least one selected from the group consisting of CH ₂ ) is preferred.

（Ｒ^３１は、水素、メチル基、エチル基又はプロピル基を表す。Ｒ^３２は、−Ｏ−、−ＮＨ−を表す。Ｒ^４１は、メチレン基、エチレン基又はプロピレン基を表す。Ｒ^５１は、ケトン基を表し、存在しなくてもよい。ｗ１は、１〜１００の整数を表す。ｚは、１〜６の整数を表す。）

（Ｒ^３１は、水素、メチル基、エチル基又はプロピル基を表す。ｗ２は、４〜１０の整数を表す。ｚは、１〜６の整数を表す。）

（Ｒ^３１は、水素、メチル基、エチル基又はプロピル基を表す。ｗ３及びｗ４は、各々独立に１〜６の整数を表す。ｚは、１〜６の整数を表す。）

（Ｒ^３１は、水素、メチル基、エチル基又はプロピル基を表す。ｗ３及びｗ４は、各々独立に１〜６の整数を表す。ｚは、１〜６の整数を表す。αは、０〜２の整数を表す。） As the fluoroalkyl group-containing monomer, it is also preferable to use a compound represented by the following formula (3), (4), (5) or (6).

(R ³¹ represents hydrogen, a methyl group, an ethyl group or a propyl group. R ³² represents —O— or —NH—. R ⁴¹ represents a methylene group, an ethylene group or a propylene group. R ⁵¹ represents And represents a ketone group, and may not exist. W1 represents an integer of 1 to 100. z represents an integer of 1 to 6.)

(R ³¹ represents hydrogen, a methyl group, an ethyl group, or a propyl group. W2 represents an integer of 4 to 10. z represents an integer of 1 to 6.)

(R ³¹ represents hydrogen, a methyl group, an ethyl group, or a propyl group. W3 and w4 each independently represent an integer of 1 to 6. z represents an integer of 1 to 6.)

(R ³¹ represents hydrogen, a methyl group, an ethyl group, or a propyl group. W3 and w4 each independently represent an integer of 1 to 6. z represents an integer of 1 to 6. α represents 0 to 0. Represents an integer of 2.)

Moreover, a fluoroalkylene oxide group or a fluorobenzyl group-containing monomer is also suitable as the fluoro group-containing monomer.

Examples of the fluoro group-containing monomer include [1H, 1H-perfluoro (2,5-dimethyl-3,6-dioxananoyl)] acrylate, [1H, 1H-perfluoro (2,5-dimethyl-3,6-dioxananoyl)]. Preference is given to at least one selected from the group consisting of methacrylate, pentafluorobenzoyl acrylate, pentafluorobenzoyl methacrylate, and 2,3,5,6-tetrafluoromethacrylate.

In the surface modification method, the radical polymerizable monomer (liquid) or a solution thereof contains a polymerization inhibitor, and it is preferable to perform polymerization in the presence of the polymerization inhibitor. Here, 4-methylphenol is preferable as the polymerization inhibitor.

In the surface modification method, the length of the polymer chain formed is preferably 10 to 50000 nm.

The present invention relates to a surface-modified elastic body obtained by the surface modification method.
The present invention relates to a surface-modified elastic body required to have slidability, low friction or low water resistance in the presence of water or in a dry state obtained by the surface modification method.
The present invention relates to a surface-modified elastic body obtained by modifying at least a part of a three-dimensional solid surface by the surface modification method. Here, the surface-modified elastic body is preferably a polymer brush.

The present invention further relates to a syringe gasket having at least a part of the surface modified by the surface modification method.
The present invention further relates to a tire having at least a part of the groove surface of the tire modified by the surface modification method.

According to the present invention, the surface 1 of vulcanized rubber or thermoplastic elastomer (modification target) is irradiated with LED light of 300 nm to 400 nm to form a polymerization initiation point from the photosensitizer on the surface; And surface modification including step 2 of radical polymerization by irradiating 300 to 400 nm of LED light from the polymerization starting point to grow a polymer chain on the surface of the modification object. Since it is a method, it can provide the surface of the object to be modified with excellent slidability and durability against repeated sliding, and can also provide good sealing properties. Therefore, by forming a polymer chain on the surface of an object using this method, it is possible to provide a surface-modified elastic body such as a gasket for a syringe excellent in the above performance. Further, since the modified surface-modified elastic body does not have a PTFE polymer skeleton, it can be sterilized with radiation such as γ rays. Furthermore, since those having a phospholine group in the side chain are biocompatible, adsorption and aggregation of proteins in the biopharmaceutical can be prevented. On the other hand, by forming a polymer chain on the inner surface of the groove of the tire, it is excellent in drainage and snow drainage, and can impart good wet grip performance, hydroplaning property and ice grip performance, so these tires have excellent performance Can provide.

It is an example of the side view of embodiment of the gasket for syringes. It is an example of the expanded view of the tread part of a pneumatic tire (whole figure not shown). It is an example of A1-A1 sectional drawing of FIG.

A surface modification method using a vulcanized rubber or a thermoplastic elastomer as a modification target, wherein the surface of the modification target is irradiated with 300 to 400 nm LED light and polymerized from a photosensitizer on the surface. Starting from step 1 for forming the starting point and the polymerization starting point, the radical polymerizable monomer is radically polymerized by irradiating 300 nm to 400 nm LED light to grow a polymer chain on the surface of the modification target. Step 2 is included.

In step 1, on the surface of the rubber after vulcanization molding or the thermoplastic elastomer after the molding (modification target), the photosensitizer existing on the surface is irradiated with LED light of 300 to 400 nm. As a result, a polymerization starting point derived from the photosensitizer is formed on the surface of the object to be modified.

As the vulcanized rubber and the thermoplastic elastomer, those having a carbon atom adjacent to the double bond (allylic carbon atom) are preferably used.

Examples of rubbers to be modified include diene rubbers such as styrene butadiene rubber, butadiene rubber, isoprene rubber, natural rubber, and deproteinized natural rubber, and butyl rubber and halogenated butyl rubber containing isoprene units as a degree of unsaturation. Is mentioned. In the case of butyl rubber and halogenated butyl rubber, a crosslinked rubber made of triazine is preferred because the extract from the vulcanized rubber is reduced. In this case, an acid acceptor may be included, and suitable acid acceptors include hydrotalcite and magnesium carbonate.

In the case of other rubbers, sulfur vulcanization is preferred. In that case, you may add compounding agents, such as a vulcanization accelerator generally used by sulfur vulcanization, a zinc oxide, a filler, and a silane coupling agent. As the filler, carbon black, silica, clay, talc, calcium carbonate and the like can be suitably used.

The rubber vulcanization conditions may be set as appropriate, and the rubber vulcanization temperature is preferably 150 ° C. or higher, more preferably 170 ° C. or higher, and still more preferably 175 ° C. or higher.

As the thermoplastic elastomer, for example, a polymer compound having a rubber elasticity at normal temperature (thermoplastic elastomer (TPE) such as a styrene-butadiene styrene copolymer) by a collection of plastic components (hard segments) serving as a crosslinking point Etc .; a high molecular compound having rubber elasticity in which a thermoplastic component and a rubber component are mixed and dynamically crosslinked by a crosslinking agent (including a styrene block copolymer or an olefin resin and a crosslinked rubber component) And thermoplastic elastomers (TPV) such as polymer alloys).

Other suitable thermoplastic elastomers include nylon, polyester, urethane, polypropylene, and their dynamically crosslinked thermoplastic elastomers. In the case of a dynamically crosslinked thermoplastic elastomer, a material obtained by dynamically crosslinking a halogenated butyl rubber in a thermoplastic elastomer is preferable. In this case, the thermoplastic elastomer is preferably nylon, urethane, polypropylene, SIBS (styrene-isobutylene-styrene block copolymer) or the like.

The polymerization starting point is, for example, by adsorbing the photosensitizer to the surface by treating the surface of the modification target with a photosensitizer, and then irradiating the treated surface with 300 to 400 nm LED light. Thus, a polymerization initiator can be formed.

Examples of the photosensitizer include organic sulfur compounds such as carbonyl compounds and tetraethylthiuram disulfide, persulfides, redox compounds, azo compounds, diazo compounds, halogen compounds, and photoreductive dyes. Carbonyl compounds are preferred.

As the carbonyl compound as a photosensitizer, benzophenone and its derivatives are preferable. For example, a benzophenone compound represented by the following formula (1) can be preferably used.

(In the formula (1), R ^{1 to} R ⁵ and R ¹ ′ to R ⁵ ′ are the same or different and represent a hydrogen atom, an alkyl group, a halogen (fluorine, chlorine, bromine, iodine), a hydroxyl group, or a 1-3 grade. An amino group, a mercapto group, or a hydrocarbon group that may contain an oxygen atom, a nitrogen atom, or a sulfur atom, and any two adjacent groups connected to each other to form a ring structure together with the carbon atoms to which they are bonded May be good.)

Specific examples of benzophenone compounds include benzophenone, xanthone, 9-fluorenone, 2,4-dichlorobenzophenone, methyl o-benzoylbenzoate, 4,4'-bis (dimethylamino) benzophenone, 4,4'-bis ( And diethylamino) benzophenone. Among these, benzophenone, xanthone, and 9-fluorenone are particularly preferable because a polymer brush can be obtained satisfactorily.

As the benzophenone compound, a fluorobenzophenone compound can also be suitably used, and examples thereof include 2,3,4,5,6-pentafluorobenzophenone and decafluorobenzophenone represented by the following formula.

As a method for adsorbing a photosensitizer such as a benzophenone-based compound on the surface of the object to be modified, a known method may be used. For example, for benzophenone compounds, the surface part of the object to be modified is adsorbed on the surface by treatment with a solution obtained by dissolving benzophenone compounds in an organic solvent, and the organic solvent is dried as necessary. The polymerization starting point is formed by evaporation. The surface treatment method is not particularly limited as long as the benzophenone compound solution can be brought into contact with the surface of the object to be modified. For example, the benzophenone compound solution is applied, sprayed, and immersed in the solution. Etc. are suitable. Furthermore, when the surface modification is necessary only on a part of the surface, the sensitizer may be adsorbed only on the part of the necessary surface. In this case, for example, application of the solution, spraying of the solution Etc. are suitable. As the solvent, methanol, ethanol, acetone, benzene, toluene, methyl ethyl ketone, ethyl acetate, THF, and the like can be used. Acetone is preferable because it does not swell the object to be modified, and is quick to dry and evaporate.

The surface to be modified is subjected to a surface treatment with a benzophenone-based compound solution to adsorb the photosensitizer, and then the surface after treatment is irradiated with 300 to 400 nm LED light to adsorb the photosensitizer. Is preferably chemically bonded to the surface. Thereby, the benzophenone-based compound can be immobilized on the surface. The wavelength of the LED light is more preferably 355 to 380 nm, and still more preferably an LED lamp having a wavelength of 355 nm, 360 nm, 365 nm, 370 nm, 375 nm, and 380 nm. Particularly preferred is 365 nm, which is close to the absorption wavelength of benzophenone of 366 nm. In the step 1 and the immobilization, hydrogen on the rubber surface is extracted, and a covalent bond is formed between C═O carbon of benzophenone and carbon on the rubber surface. At the same time, the extracted hydrogen is oxygen of C═O. To form C—O—H. Further, since this hydrogen abstraction reaction is selectively performed with hydrogen at the allylic position of the reforming target, it is preferable that the rubber contains butadiene and isoprene units having allyl hydrogen.

In step 2, starting from the polymerization start point formed in step 1, the radical polymerizable monomer is irradiated with 300 nm to 400 nm LED light to undergo radical polymerization, and a polymer chain is grown on the surface of the modification target.

In step 2, a fluoro group-containing monomer can be suitably used as the radical polymerizable monomer. Examples of the fluoro group-containing monomer include fluoroalkyl group-containing monomers. The fluoroalkyl group-containing monomer is not particularly limited as long as it is a compound having one radical polymerizable group such as a vinyl group and at least one fluoroalkyl group. Here, the fluoroalkyl group is a group in which at least one hydrogen atom of the alkyl group is substituted with a fluorine atom, more preferably a fluoroalkyl group having 7 to 30 carbon atoms, and a carbon having a perfluoroalkyl group at the terminal. A fluoroalkyl group of 7 to 30 is particularly preferable.

In the fluoroalkyl group-containing monomer, the proportion of the amount of fluorine atoms in the monomer is preferably 45% by mass or more, and more preferably 50% by mass or more with respect to the molecular weight of the monomer.

As the fluoroalkyl group-containing monomer, a compound represented by AB (A is a radical polymerizable group and B is a fluoroalkyl group) can be preferably used. For example, it is shown by the following formula.

(In the formula, Ra represents a hydrogen atom, a methyl group, an ethyl group or a propyl group. A represents —O— or —NH—. B represents an alkylene group or polyoxy which may have a substituent. Represents an alkylene group and may not be present, C represents a ketone group and may not be present, and Rf represents a fluoroalkyl group which may have a substituent.

The carbon number of the alkylene group represented by B is preferably 1-15, the polyoxyalkylene group is represented by (RO) _w , the carbon number of R is 1-10, and the polymerization degree w is preferably 1-150, The alkylene group and the polyoxyalkylene group may have a substituent. Furthermore, Rf is preferably a C2-C40 fluoroalkyl group having a perfluoroalkyl group at the terminal, and may have a substituent. The substituent in B and Rf is not particularly limited, and examples thereof include a hydroxyl group.

As the fluoroalkyl group-containing monomer, a compound represented by the following formula (2) is preferable because polymerization is easy.

(Wherein R ²¹ is a hydrogen atom, methyl group, ethyl group or propyl group, R ²² is an alkylene group having 1 to 4 carbon atoms, Rf is a fluoroalkyl group having 7 to 30 carbon atoms having a perfluoroalkyl group at the terminal) Is shown.)

R ²¹ is preferably a hydrogen atom or a methyl group, and R ²² is preferably an alkylene group having 1 to 3 carbon atoms. Rf is preferably a C7-20 fluoroalkyl group having a perfluoroalkyl group at the terminal.

Suitable compounds represented by the formula (2) include (meth) acrylate compounds represented by the following formulas (2-1) to (2-3).

(In the formula, R ²³ represents a hydrogen atom or a methyl group, and k represents 7, 8, 9, 10, 11 or 12.)

Specific examples of the fluoroalkyl group-containing monomer include 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12. _{, 12-heneicosafluorododecyl acrylate (H 2} C = CHCO 2 CH 2 CH 2 (CF 2) 9 CF 3), 3,3,4,4,5,5,6,6,7,7,8,8,9 _{, 9,10,10,10-Heptadecafluorodecyl acrylate (H 2} C = CHCO 2 CH 2 CH 2 (CF 2) 7 CF 3), H 2 C = CHCO 2 CH 2 (CF 2) 9 CF 3, H 2 C = CHCO ₂ CH ₂ (CF ₂ ) ₇ CF ₃ , ₃ , ₃ , 4, ₄ , 5, 5, 6, 6, _{7, 7} , 8, 8, 9, 9, 10, 10, 11, 11, 12 , 12,12- eneicosafluoridomethylacrylate, 3,3,4,4,5,5,6,7,7,8,8,9,9,10,10,10-Heptadecafluorodemethyl methacrylate, 3- (perfluoropropyl) -2-hydroxypropyl _{(F (CF 2) 4 CH} 2 CH (OH) CH 2 OCOCH = CH 2), 3-perfluorohexyl-2-hydroxypropyl acrylate (F (CF 2) 6 CH 2 CH (OH) CH 2 OCOCH = CH 2), 3- (perfluoro-3-methylbutyl) -2-hydroxypropyl acrylate ((CF 3) 2 CF (CF 2) 2 CH 2 CH (O _{H) CH 2 OCOCH = CH 2} ), 3- (perfluoro-5-methylhexyl) -2-hydroxypropyl acrylate ((CF 3) 2 CF (CF 2) 4 CH 2 CH (OH) CH 2 OCOCH = CH 2) , etc. Is mentioned. Above all, because it is highly resistant to γ-ray sterilization,
3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,12-heneicosafluorodecyl acrylate (H ₂ C = CHCO _{2 CH 2 CH 2 (CF 2} ) 9 CF 3), 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-Heptadecafluorodecyl acrylate _{(H 2 C = CHCO 2 CH} 2 CH 2 (CF 2) 7 CF 3), 3- (perfluorobutyl) -2-hydroxypropyl acrylate (F (CF 2) 4 CH 2 CH (OH) CH 2 OCOCH = CH 2) , 3-perfluorohexyl-2-hydroxypropyl acrylate (F (CF 2) _{CH 2 CH (OH) CH 2} OCOCH = CH 2), 3- (perfluoro-3-methylbutyl) -2-hydroxypropyl acrylate ((CF 3) 2 CF (CF 2) 2 CH 2 CH (OH) CH 2 OCOCH = _{CH 2), 3- (perfluoro-} 5-methylhexyl) -2-hydroxypropyl acrylate ((CF 3) 2 CF (CF 2) 4 CH 2 CH (OH) CH 2 OCOCH = CH 2) is preferred. These can be used alone or in combination of two or more.

A vinyl monomer having a fluoroalkyl group in the side chain can be used as the fluoroalkyl group-containing monomer, and among them, a monomer having a fluoroalkyl group at the end of the side chain and an oxyalkylene group at a position close to the double bond side is preferable. . Specifically, a monomer represented by the following formula (3) can be preferably used.

(In formula (3), R ³¹ represents hydrogen, a methyl group, an ethyl group or a propyl group. R ³² represents —O— or —NH—. R ⁴¹ represents a methylene group, an ethylene group or a propylene group. R ⁵¹ represents a ketone group and may not be present, w1 represents an integer of 1 to 100, and z represents an integer of 1 to 6.)

Moreover, as a fluoroalkyl group containing monomer, the monomer represented by following formula (4), (5), (6) is also suitable.

(In formula (4), R ³¹ represents hydrogen, a methyl group, an ethyl group, or a propyl group. W2 represents an integer of 4 to 10. z represents an integer of 1 to 6.)

(In the formula ^{(5), R 31} is hydrogen, the .w3 and w4 represents a methyl group, an ethyl group or a propyl group, is .z representing each independently a 1-6 integer, an integer from 1 to 6 .)

(In formula (6), R ³¹ represents hydrogen, a methyl group, an ethyl group, or a propyl group. W3 and w4 each independently represent an integer of 1 to 6. z represents an integer of 1 to 6. Α represents an integer of 0 to 2.)

A structure having high molecular mobility such as (R ⁴¹ O) _w1 and (CH ₂ ) _{w2 is formed} between CH ₂ = CR ³¹ that becomes a main chain after polymerization and a fluoroacryl group of (CF ₂ ) _z CF _3. By placing, the (CF ₂ ) _z CF ₃ group or the CF ₃ group tends to be unevenly distributed on the surface in the dry state, which is preferable in terms of improving the slidability.

As the fluoro group-containing monomer, a fluoroalkylene oxide group or fluorobenzyl group-containing monomer can also be suitably used. Since the fluoroalkyl oxide group is —CF ₂ — or —CF ₃ , the surface free energy is lowered and the slidability is not only high, but also there is an oxide that is easy to rotate. It is preferable in terms of improving the properties. In addition, the fluorobenzyl group is preferable from the viewpoint of increasing antibacterial properties.

Other specific examples of the fluoro group-containing monomer include [1H, 1H-perfluoro (2,5-dimethyl-3,6-dioxananoyl)] acrylate, [1H, 1H-perfluoro (2,5-dimethyl) represented by the following formula. −3,6-dioxanoanoyl)] methacrylate, pentafluorobenzoyl acrylate, pentafluorobenzoyl methacrylate, 2,3,5,6-tetrafluorophenyl methacrylate are also preferred.

As a method of radical polymerization of the radical polymerizable monomer in Step 2, a radical polymerizable monomer (liquid) or a solution thereof is applied (sprayed) to the surface of the modification target to which a benzophenone compound or the like is adsorbed or covalently bonded. Alternatively, the object to be modified is immersed in a radical polymerizable monomer (liquid) or a solution thereof and irradiated with LED light of 300 nm to 400 nm, radical polymerization (photo radical polymerization) proceeds, and the surface of the object to be modified The polymer chain grows. Further, after the coating, the surface is covered with transparent glass, PET, polycarbonate or the like, and radical polymerization (photo radical polymerization) proceeds by irradiating LED light of 300 nm to 400 nm from the surface, and the surface of the object to be modified It is also possible to grow polymer chains.

In step 2, radical polymerization (photo radical polymerization) is preferably progressed by irradiating a 300-400 nm LED light to a radical polymerizable monomer to which a reducing agent or an antioxidant is added. In this case, a reducing agent or antioxidant is desirable because it supplements oxygen in the system. The radically polymerizable monomer to which the reducing agent or antioxidant is added may be a mixture of the respective components or a separated one. In addition, after the radically polymerizable monomer is first brought into contact with the modification target obtained in step 1, the components are first mixed and the mixed material is mixed even if a reducing agent and an antioxidant are further added thereto. You may make it contact with a modification target.

Specifically, the modification target in which the polymerization initiation point by the photosensitizer obtained in Step 1 is formed on the surface, a radical polymerizable monomer (liquid) or a solution thereof in a reducing agent or an antioxidant substance After contact with a substance to which is added (dipping, coating, etc.), or the modification object is brought into contact with a radical polymerizable monomer (liquid) or a solution thereof, and a reducing agent or antioxidant is further formed thereon. After placing the substance solution, radical polymerization can be performed by a method of irradiating the LED light.

For example, since the fluoroalkyl group-containing monomer has a specific gravity greater than 1 and does not mix with water, the reducing agent or antioxidant solution is separated and rides on the radical polymerizable monomer (liquid) or its solution. .

The reducing agent and the antioxidant are not particularly limited, and a compound having such an action can be used as appropriate. For example, retinol, dehydroretinol, retinol acetate, retinol palmitate, retinal, retinoic acid, vitamin A oils such as vitamin A oil, derivatives and salts thereof; α-carotene, β-carotene, γ-carotene, cryptoxanthine , Carotenoids such as astaxanthin and fucoxanthin and derivatives thereof; pyridoxine, pyridoxal, pyridoxal-5-phosphate, vitamin Bs such as pyridoxamine, derivatives and salts thereof; ascorbic acid, sodium ascorbate, ascorbyl stearate Vitamin Cs such as ascorbyl palmitate, ascorbyl dipalmitate, magnesium ascorbate, derivatives thereof and salts thereof;
Vitamin Ds such as ergocalciferol, cholecalciferol, 1,2,5-dihydroxy-cholecalciferol, derivatives and salts thereof; α-tocopherol, β-tocopherol, γ-tocopherol, δ-tocopherol, α Vitamin Es such as tocotrienol, β-tocotrienol, γ-tocotrienol, δ-tocotrienol, tocopherol acetate, tocopherol nicotinate, their derivatives and their salts; Trolox, their derivatives and their salts; dihydroxytoluene, butylhydroxy Toluene, butylhydroxyanisole, dibutylhydroxytoluene, α-lipoic acid, dehydrolipoic acid, glutathione, derivatives thereof and salts thereof; erythrates such as uric acid, erythorbic acid, sodium erythorbate Ruvic acid, derivatives thereof and salts thereof; gallic acid such as gallic acid and propyl gallate, derivatives thereof and salts thereof; rutin such as rutin and α-glycosyl-rutin, derivatives thereof and salts thereof; tryptophan, derivatives thereof Histidine, its derivatives and their salts; cysteine derivatives such as N-acetylcysteine, N-acetylhomocysteine, N-octanoylcysteine, N-acetylcysteine methyl ester and their salts; N, N ′ Cystine derivatives such as diacetylcystine dimethyl ester, N, N′-dioctanoyl cystine dimethyl ester, N, N′-dioctanoyl homocystine dimethyl ester and salts thereof; carnosine, derivatives thereof and salts thereof; homocarnosine, Derivatives and salts thereof Anserine, derivatives thereof and salts thereof; calcinin, derivatives thereof and salts thereof; dipeptides or tripeptide derivatives containing histidine and / or tryptophan and / or histamine and salts thereof; flavanones, flavones, anthocyanins, anthocyanidins, flavonols; Flavonoids such as quercetin, quercitrin, myricetin, fisetin, hamelitannin, catechin, epicatechin, gallocatechin, epigallocatechin, epicatechin gallate, epigallocatechin gallate; tannic acid, caffeic acid, ferulic acid, protocatechuic acid, chalcone, Oryzanol, carnosol, sesamol, sesamin, sesamorin, zingerone, curcumin, tetrahydrocurcumin, clobamide, deoxyclobamide, ginger , Capsaicin, vanillyl amide, ellagic acid, bromophenol, flavoglasin, melanoidin, riboflavin, riboflavin butyrate, flavin mononucleotide, flavin adenine nucleotide, ubiquinone, ubiquinol, mannitol, bilirubin, cholesterol, ebselen, selenomethionine, ceruloplasmin, transferrin, Examples include lactoferrin, albumin, superoxide dismutase, catalase, glutathione peroxidase, metallothionein, and O-phosphono-pyridoxylidene rhodamine. You may use these individually or in combination of 2 or more types.

Among these, riboflavin, ascorbic acid, α-tocopherol, β-carotene, and uric acid are preferable because of high oxygen scavenging ability, and riboflavin and ascorbic acid are particularly preferable.

When using the solution of a reducing agent and an antioxidant substance, the concentration of the reducing agent and the antioxidant substance is preferably 10 ⁻⁴ to 1% by mass, and more preferably 10 ^{−3 to} 0.1% by mass.
Further, the amount of the radical polymerizable monomer used may be appropriately set depending on the length of the polymer chain to be formed, the performance exhibited by the chain, and the like. Furthermore, the amount of reducing agent and antioxidant used may be set appropriately from the viewpoint of supplementing oxygen in the system.

Conventionally known materials and methods can be applied to the coating (spraying) solvent, the coating (spraying) method, the dipping method, the irradiation conditions, and the like. In addition, as a solution of a radically polymerizable monomer, a solution in which an aqueous solution or a photosensitizer to be used (such as a benzophenone compound) is dissolved in an organic solvent is used. Moreover, what contains well-known polymerization inhibitors, such as 4-methylphenol, can also be used as a radically polymerizable monomer (liquid) and its solution.

In the present invention, radical polymerization proceeds by irradiating LED light after application of the monomer (liquid) or a solution thereof or immersion in the monomer or the solution thereof. The amount of irradiation light may be appropriately set in consideration of the polymerization time and the uniformity of the progress of the reaction. In order to prevent polymerization inhibition due to active gas such as oxygen in the reaction vessel, it is preferable to remove oxygen in the reaction vessel or in the reaction solution at the time of light irradiation or before light irradiation. Therefore, introducing an inert gas such as nitrogen gas or argon gas into the reaction vessel or in the reaction liquid and discharging the active gas such as oxygen out of the reaction system, and replacing the inside of the reaction system with an inert gas atmosphere, Etc. are performed as appropriate. Furthermore, in order to prevent reaction inhibition such as oxygen, the LED irradiation light source is installed at a position where an air layer (oxygen content of 15% or more) does not enter between the reaction vessel such as glass or plastic and the reaction solution or the modification target. A device such as the above is also appropriately performed.

When irradiating LED light, the wavelength is 300 to 400 nm, preferably 355 to 380 nm. Thereby, a polymer chain can be favorably formed on the surface of the object to be modified. As the light source, an LED having a central wavelength of 365 nm, an LED having a central wavelength of 375 nm, or the like can be used. Among them, an LED having a central wavelength of 365 nm close to the excitation wavelength of benzophenone of 366 nm is preferable from the viewpoint of efficiency.

Moreover, as a polymer chain formed at the process 2, what is formed by superposition | polymerization of the fluoroalkyl group containing monomer represented by the said Formula (2) is preferable. Thereby, excellent slidability and durability can be obtained, and good sealing performance can be maintained. The degree of polymerization of the formed polymer chain is preferably 20 to 200000, more preferably 350 to 50000.

The length of the polymer chain formed in step 2 is preferably 10 to 50000 nm, more preferably 100 to 50000 nm. If it is less than 10 nm, there is a tendency that good slidability cannot be obtained. If it exceeds 50000 nm, further improvement in slidability cannot be expected, and the cost of raw materials tends to increase due to the use of expensive monomers, and the surface pattern by surface treatment becomes visible to the naked eye. There is a tendency to deteriorate the sealing performance.

In the above step 2, two or more monomers may be radically polymerized starting from the polymerization start point, and a plurality of polymer chains may be grown on the surface of the modification target. The surface modification method of the present invention may crosslink between polymer chains. In this case, ionic crosslinking, crosslinking with a hydrophilic group having an oxygen atom, or crosslinking with a compound having a halogen group such as iodine may be formed between the polymer chains.

By applying the surface modification method to vulcanized rubber or thermoplastic elastomer, a surface modified elastic body can be obtained. The obtained surface-modified elastic body is excellent in slidability in the presence of water or in a dry state. Low friction and excellent water resistance. Further, by applying the method to at least a part of a three-dimensional solid (such as an elastic body), a modified surface-modified elastic body can be obtained. Furthermore, a polymer brush (polymer brush) is mentioned as a preferable example of the surface modified elastic body. Here, the polymer brush means a grafting graft polymer by surface-initiated living radical polymerization. In addition, the graft chain is preferably oriented in the substantially vertical direction from the surface of the modification target because the entropy is reduced and the molecular motion of the graft chain is lowered, so that the slidability is obtained. Furthermore, as the brush density, a quasi-density and a density brush that are 0.01 chains / nm ² or more are preferable.

Further, by applying the surface modification method to vulcanized rubber or thermoplastic elastomer, a syringe gasket having at least a part of the modified surface can be produced. The modification is preferably performed at least on the sliding portion of the gasket surface, and may be performed on the entire surface.

FIG. 1 is an example of a side view of an embodiment of a syringe gasket. The gasket 1 shown in FIG. 1 has three annular protrusions 11a, 11b, and 11c that continuously protrude in the circumferential direction on the outer peripheral surface that contacts the inner peripheral surface of the syringe barrel of the syringe. In the gasket 1, the surface modification is applied to (1) the surface of the protruding portion in contact with the syringe such as the annular protruding portions 11 a, 11 b, 11 c, and (2) the side surface including the annular protruding portions 11 a, 11 b, 11 c. The entire surface includes (3) the entire surface of the side surface and the surface 13 of the bottom surface portion.

Furthermore, by applying the surface modification method to a groove formed in a tread of a tire used in a vehicle such as a passenger car and generating a polymer brush in the groove, the fluid resistance of the groove surface on a wet or snowy road surface is reduced. Or the contact angle with water is increased, water and snow can be eliminated and brushed, and the grip can be improved.

FIG. 2 shows an example of a development view of the tread portion 2 of the pneumatic tire (not shown), and FIG. 3 shows an example of the A1-A1 cross-sectional view of FIG.
2 to 3, the central vertical groove 3 a (groove depth D <b> 1) and the shoulder vertical groove 3 b (groove depth D <b> 2) are constituted by straight grooves extending linearly in the tire circumferential direction. Such straight grooves can reduce drainage resistance and exhibit high drainage performance when traveling straight ahead.

The pneumatic tire has a narrow groove 5 (groove depth D3) extending in the tire circumferential direction on the shoulder longitudinal groove 3b side, and an intermediate inclined groove 6 (groove) extending from the narrow groove 5 toward the central longitudinal groove 3a. Depth D4), joint groove 7 (groove depth D5) that is located on the inner side in the tire axial direction than the narrow groove 5 and that connects between the intermediate inclined grooves 6 and 6 adjacent in the tire circumferential direction, and from the shoulder vertical groove 3b to the tire Shoulder lateral grooves 8, 8 a, 8 b (groove depth D 6) and the like that extend to the outside are arranged, and drainage performance can be exhibited even with such grooves. And the above-mentioned effect is exhibited by applying the method to these grooves.

EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited only to these.

Example 1
A vulcanized rubber (vulcanized at 180 ° C. for 10 minutes) obtained by crosslinking chlorobutyl rubber containing an isoprene unit (unsaturation: 1 to 2%) with triazine is immersed in a 3 wt% acetone solution of benzophenone, and is then applied to the surface of the vulcanized rubber. Benzophenone was adsorbed. The LED light having a wavelength of 365 nm was irradiated for 10 minutes to fix the benzophenone. Thereafter, the vulcanized rubber was taken out and dried.
3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-Heptadecafluordecylate (manufactured by Sigma Aldrich) on the surface of the dried vulcanized rubber The liquid was applied, and the surface was covered with a glass plate. Radiation polymerization was performed by irradiating an LED light having a wavelength of 365 nm from above the glass plate for 2 hours to grow a polymer chain on the rubber surface to obtain a surface-modified elastic body (polymer brush).

(Example 2)
Surface-modified elastic body in the same manner as in Example 1 except that 3-perfluorohexyl-2-hydroxypropyl acrylate (F (CF ₂ ) ₆ CH ₂ CH (OH) CH ₂ OCOCH═CH ₂ : R1633 manufactured by Daikin Industries, Ltd.) was used. (Polymer brush) was produced.

(Example 3)
Example except that 3- (perfluoro-3-methylbutyl) -2-hydroxypropyl acrylate ((CF ₃ ) ₂ CF (CF ₂ ) ₂ CH ₂ CH (OH) CH ₂ OCOCH = CH ₂ : manufactured by FluoroChem) was used In the same manner as in Example 1, a surface-modified elastic body (polymer brush) was produced.

Example 4
Example except that 3- (perfluoro-5-methylhexyl) -2-hydroxypropyl acrylate ((CF ₃ ) ₂ CF (CF ₂ ) ₄ CH ₂ CH (OH) CH ₂ OCOCH = CH ₂ : manufactured by FluoroChem) In the same manner as in Example 1, a surface-modified elastic body (polymer brush) was produced.

(Example 5)
A vulcanized rubber (vulcanized at 180 ° C. for 10 minutes) obtained by crosslinking chlorobutyl rubber containing an isoprene unit (unsaturation: 1 to 2%) with triazine is immersed in a 3 wt% acetone solution of benzophenone, and is then applied to the surface of the vulcanized rubber. Benzophenone was adsorbed. The LED light having a wavelength of 365 nm was irradiated for 10 minutes to fix the benzophenone. Thereafter, the vulcanized rubber was taken out and dried.
3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-Heptadecafluordecylate (manufactured by Sigma Aldrich) on the surface of the dried vulcanized rubber A riboflavin aqueous solution (concentration 0.0093 mmol / L) was placed on the solution. The aqueous solution was not mixed with the monomer solution, and the aqueous solution was separated into the upper layer because the specific gravity of the monomer solution was lighter. Then, LED light having a wavelength of 365 nm from the top was irradiated for 2 hours to perform radical polymerization to grow a polymer chain on the rubber surface to obtain a surface-modified elastic body (polymer brush).

(Comparative Example 1)
A vulcanized rubber (vulcanized at 180 ° C. for 10 minutes) itself obtained by crosslinking chlorobutyl rubber containing an isoprene unit (unsaturation degree: 1 to 2%) with triazine was used.

The surface-modified elastic bodies produced in Examples and Comparative Examples were evaluated by the following methods.
(Polymer chain length)
The length of the polymer chain formed on the surface of the vulcanized rubber was measured using an SEM at an acceleration voltage of 15 kV and 1000 times the cross section of the modified rubber on which the polymer chain was formed. The film thickness of the polymer layer was taken as the length of the polymer chain.

(Static friction coefficient and dynamic friction coefficient)
The static friction coefficient and dynamic friction coefficient of the surface of the surface-modified elastic body, and the static friction coefficient and dynamic friction coefficient of the sample surface where 200 μL of water was dropped on each surface were measured in accordance with the method specified in ASTM D1894. Moreover, the sample was made to contact with borosilicate glass, and the frictional force between borosilicate glass was measured. The load for measuring the friction coefficient was 200 g, the tensile speed was 600 mm / min, and the load distance was 10 cm. The apparatus used was Haydon type 14 (manufactured by Shinto Kagaku Co., Ltd.).

From Table 1, the surface-modified elastic body surface produced in the example is compared with the non-modified vulcanized rubber of Comparative Example 1,
It was revealed that the coefficient of static friction and the coefficient of dynamic friction were greatly reduced, and good slidability was obtained. Moreover, since only the surface was modified, the sealing performance was equivalent to that of Comparative Example 1.

Therefore, when it is used as a gasket for a plunger of a syringe, the frictional force of the plunger against the syringe is reduced with a sufficient sealing property, and the treatment with the syringe can be performed easily and accurately. Further, since the difference between the static friction coefficient and the dynamic friction coefficient is small, the start of pushing the plunger and the subsequent plunger approaching operation can be performed smoothly without pulsating. Further, when a syringe syringe is made of a thermoplastic elastomer and a polymer chain is formed on the inner surface thereof, prescription by a syringe can be easily performed as described above.

In addition, by forming polymer chains on the surface of grooves, sidewalls, diaphragms, skis and snowboard boards, swimming swimsuits, road signs, signboards, etc. formed on the tread of tires used in passenger cars etc. Can also be expected.

DESCRIPTION OF SYMBOLS 1 Gasket 11a, 11b, 11c Annular projection part 13 Surface 2 of a bottom part 2 Tread part 3a Center vertical groove 3b Shoulder vertical groove 5 Narrow groove 6 Intermediate inclination groove 7 Joint groove 8, 8a, 8b Shoulder horizontal groove

Claims (16)

A surface modification method using a vulcanized rubber or a thermoplastic elastomer as a modification object,
Irradiating the surface of the modification target with 300 to 400 nm LED light, and forming a polymerization initiation point from the photosensitizer on the surface; and
The polymerization initiation points in the starting point, the radical polymerizable monomer by irradiating LED light 300nm~400nm by radical polymerization, seen including a step 2 of growing polymer chains to the surface of the object to be modified,
A surface modification method in which the radical polymerizable monomer is a fluoro group-containing monomer . In the step 2, starting from the polymerization starting point, a radical polymerizable monomer to which a reducing agent or an antioxidant is added is subjected to radical polymerization by irradiating 300 to 400 nm LED light, and the surface of the modification target 2. The surface modification method according to claim 1, wherein polymer chains are grown on the surface. The surface modification method according to claim 1 or 2, wherein the vulcanized rubber or the thermoplastic elastomer has an allylic carbon atom which is a carbon atom adjacent to a double bond. The surface modification method according to claim 1, wherein the photosensitizer is a benzophenone compound represented by the following formula (1).

(In formula (1), R ^{1 to} R ⁵ and R ¹ ′ to R ⁵ ′ are the same or different and are a hydrogen atom, an alkyl group, a halogen, a hydroxyl group, a ^primary to tertiary amino group, a mercapto group, or an oxygen atom. Represents a hydrocarbon group which may contain a nitrogen atom or a sulfur atom, and any two adjacent groups may be connected to each other to form a ring structure together with the carbon atom to which they are bonded.) The surface modification method according to claim 1, wherein the reducing agent or antioxidant is at least one selected from the group consisting of riboflavin, ascorbic acid, α-tocopherol, β-carotene, and uric acid. . The surface modification method according to any one of claims 1 to 5, wherein an inert gas is introduced into a reaction vessel and a reaction solution at the time of irradiation of the LED light or before irradiation, and the polymerization is performed by replacing the inert gas atmosphere. The surface modification method according to claim 1, wherein the fluoro group-containing monomer is a fluoroalkyl group-containing monomer. The fluoroalkyl group-containing monomer is 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,12- heneicosafluorododecyl acrylate ( 3,3,4,4,5,5,6,7,7,8,8,9,9,10,10,11,11,12,12,12-heneicosafluorododecyl Acrylate, H ₂ C═CHCO ₂ CH ₂ CH ₂ (CF ₂ ) ₉ CF ₃ ), 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10 , 10,10-Heptadecafluorodecyl acrylate ( 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl acrylate, H ₂ C = CHCO _{2 CH 2 CH 2 (CF 2)} 7 CF 3), 3- (perfluorobutyl) -2-hydroxypropyl acrylate (3- ( perfluorobutyl) -2-hydroxypropyl _{acrylate, F (CF 2) 4 CH} 2 CH (OH) CH ₂ OCOCH═CH ₂ ), 3-perfluorohexyl-2-hydroxypropyl acrylate ( 3 -perfluorohexyl-2-hydroxypropyl acrylate , F (CF ₂ ) ₆ CH ₂ CH (OH) CH ₂ OCOCH═CH ₂ ), 3 - (perfluoro-3-methylbutyl) -2-hydroxypropyl acrylate (3- ( perfluoro-3-methylbutyl) -2-hydroxypropyl acrylate, (CF _{3 2 CF (CF 2) 2 CH} 2 CH (OH) CH 2 OCOCH = CH 2), and 3- (perfluoro-5-methylhexyl) -2-hydroxypropyl acrylate (3- ( perfluoro-5-methylhexyl) -2 The surface modification method according to claim 7, which is at least one selected from the group consisting of -hydroxypropyl acrylate, (CF ₃ ) ₂ CF (CF ₂ ) ₄ CH ₂ CH (OH) CH ₂ OCOCH═CH ₂ ). . The surface modification method according to claim 7, wherein the fluoroalkyl group-containing monomer is a compound represented by the following formula (3), (4), (5) or (6).

(R ³¹ represents hydrogen, a methyl group, an ethyl group or a propyl group. R ³² represents —O— or —NH—. R ⁴¹ represents a methylene group, an ethylene group or a propylene group. R ⁵¹ represents And represents a ketone group, and may not exist. W1 represents an integer of 1 to 100. z represents an integer of 1 to 6.)

(R ³¹ represents hydrogen, a methyl group, an ethyl group, or a propyl group. W2 represents an integer of 4 to 10. z represents an integer of 1 to 6.)

(R ³¹ represents hydrogen, a methyl group, an ethyl group, or a propyl group. W3 and w4 each independently represent an integer of 1 to 6. z represents an integer of 1 to 6.)

(R ³¹ represents hydrogen, a methyl group, an ethyl group, or a propyl group. W3 and w4 each independently represent an integer of 1 to 6. z represents an integer of 1 to 6. α represents 0 to 0. Represents an integer of 2.) The surface modification method according to claim 1, wherein the fluoro group-containing monomer is a fluoroalkylene oxide group or a fluorobenzyl group-containing monomer. The fluoro group-containing monomer may be [1H, 1H-perfluoro (2,5-dimethyl-3,6-dioxananoyl)] acrylate ([1H, 1H -perfluoro (2,5-dimethyl-3,6-dioxanonano). Yl)] acrylate) , [1H, 1H-perfluoro (2,5-dimethyl-3,6-dioxananoyl)] methacrylate ([1H, 1H -perfluoro (2,5-dimethyl-3,6-dioxanonanoyl) )] methacrylate), pentafluorobenzyl acrylate (pentafluorobenzyl acrylate), pentafluorobenzyl methacrylate (pentafluorobenzyl methacrylate), and 2,3, , 6-tetrafluorophenyl methacrylate surface modification method according to claim 1 is at least one selected from the group consisting of (2,3,5,6-tetrafluoro phenyl methacrylate). The radical polymerizable monomer (liquid) or a solution thereof is intended to include a polymerization inhibitor, a surface modification method according to any one of claims 1 to 11, are polymerized in the presence of a polymerization inhibitor. The surface modification method according to claim 12 , wherein the polymerization inhibitor is 4-methylphenol. The length of the polymer chains, the surface modification method according to any one of claims 1 to 13, which is a 10～50000Nm. A gasket for a syringe having at least a part of a surface modified by the surface modification method according to claim 1. A tire having at least a part of a groove surface of a tire modified by the surface modification method according to claim 1.

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