JP7275524B2 - Surface modification method and surface modified elastic body - Google Patents

Description

TECHNICAL FIELD The present invention relates to a surface modification method, and a surface-modified elastic body such as a syringe gasket having at least a portion of the surface modified by the modification method.

For parts that slide while maintaining a sealed state, such as gaskets that are integrated into the plunger of a syringe and seal the plunger and syringe, emphasis is placed on sealing performance (liquid leakage resistance), and an elastic material such as rubber is used. Although a body is used, there is a slight problem in slidability (see Patent Document 1). Therefore, the sliding surface is coated with a slidability improver such as silicone oil, but it has been pointed out that silicone oil may have an adverse effect on recently marketed biologics. On the other hand, gaskets that are not coated with a slidability improver have poor slidability, so the plunger cannot be pushed smoothly during administration, resulting in pulsation, inaccurate injection volume, and patient pain. problem arises.

In order to satisfy such contradictory requirements for sealing property and sliding property, a technique of coating a PTFE film having self-lubricating properties has been proposed (see Patent Document 2). The manufacturing cost increases and the application range is limited. In addition, there is concern about the reliability of applying products covered with PTFE films to applications requiring durability against repeated sliding. Furthermore, since PTFE is vulnerable to radiation, there is also the problem that it cannot be sterilized by radiation.

Application to other uses requiring slidability in the presence of water is also conceivable. That is, by lowering the fluid resistance of the inner surface of the prefilled syringe or the inner surface of the pipe or tube for sending water, or by raising or significantly lowering the contact angle with water, water can be sent without loss. By lowering the surface resistance of the inner and outer surfaces of the catheter tube, it is possible to facilitate insertion into the body and facilitate passage of the guide wire through the catheter. By increasing the contact angle with water on the surface of a medical device, the adhesion of specific cells (blood cells) and proteins in blood and body fluids can be suppressed. By lowering the fluid resistance of the groove surface of the tire and raising or significantly lowering the contact angle with water, the drainage of water and snow on wet and snowy roads is improved, resulting in improved grip and hydroplaning. and improve safety. It is also expected to reduce the sliding resistance of tire sidewall surfaces and building walls, and to increase the contact angle with water to make it difficult for dirt and dust to adhere.

Furthermore, pressure loss is reduced when water or an aqueous solution is sent by a diaphragm such as a diaphragm pump or a diaphragm valve. It becomes easier to slide by increasing the slidability of the running surface of skis and snowboards. By increasing the slidability of road signs and signboards to make snow slippery, the signs become easier to see. By reducing the sliding resistance of the outer peripheral surface of the ship and increasing the contact angle with water, the water resistance is reduced and bacteria are less likely to adhere to the outer peripheral surface. By improving the slidability of the yarn surface of the swimsuit, we can also expect advantageous effects such as reduced water resistance.

JP-A-2004-298220 JP 2010-142573 A

The present invention solves the above problems and provides a method for modifying the surface of vulcanized rubber that can economically and advantageously impart various functionalities such as slidability, liquid leakage resistance, and protein adsorption inhibition, and surface modification. The object is to provide an elastic body.

The present invention is a surface modification method using a vulcanized rubber as a modification target, comprising a step 1 of forming a polymerization initiation point A on the surface of the modification target, and starting from the polymerization initiation point A A step 2 of radically polymerizing a monomer to grow a polymer chain, and a step 3 of adding a silane compound to the surface of the polymer chain and further reacting it with at least a silane compound containing a fluoroalkyl group to form a modified polymer chain. It relates to a surface modification method including.

Preferably, in step 3, a silane compound is added to the surface of the polymer chain, and at least a silane compound containing a fluoroalkyl group and a silane compound containing a perfluoroether group are reacted to form a modified polymer chain.

The present invention is a surface modification method using a vulcanized rubber as an object to be modified, wherein a monomer is radically polymerized on the surface of the object to be modified in the presence of a photopolymerization initiator A to grow a polymer chain. The present invention relates to a surface modification method comprising step I and step II of adding a silane compound to the surface of the polymer chain and further reacting with at least a fluoroalkyl group-containing silane compound to form a modified polymer chain.

Preferably, in step II, a silane compound is added to the surface of the polymer chain, and at least a silane compound containing a fluoroalkyl group and a silane compound containing a perfluoroether group are reacted to form a modified polymer chain.

前記加硫ゴムは、ショアＡ硬度が５０～７０であることが好ましく、５３～６５であることがより好ましい。 The mixing ratio of the fluoroalkyl group-containing silane compound and the perfluoroether group-containing silane compound is preferably 50:50 to 100:0.
The fluoroalkyl group is preferably a group represented by the following formula.

The vulcanized rubber preferably has a Shore A hardness of 50-70, more preferably 53-65.

The monomers include acrylic acid, acrylic acid esters, alkali metal acrylic acid salts, amine acrylic acid salts, acrylamide, dimethylacrylamide, diethylacrylamide, isopropylacrylamide, hydroxyethylacrylamide, acryloylmorpholine, methoxymethyl acrylate, hydroxyethyl acrylate, methacrylic acid. , methacrylic acid esters, alkali metal methacrylic acid salts, amine methacrylic acid salts, methacrylamide, dimethyl methacrylamide, diethyl methacrylamide, isopropyl methacrylamide, hydroxyethyl methacrylamide, methacryloylmorpholine, methoxymethyl methacrylate, hydroxyethyl methacrylate, and acrylonitrile It is preferably at least one selected from the group consisting of:

The fluoroalkyl group-containing silane compound is preferably a compound represented by the following formula (1).

（式（２）中、Ｒｆ^１は、パーフルオロアルキル基を表す。Ｚは、フッ素又はトリフルオロメチル基を表す。ａ、ｂ、ｃ、ｄ、ｅは、同一若しくは異なって、０又は１以上の整数を表し、ａ＋ｂ＋ｃ＋ｄ＋ｅは、１以上であり、ａ、ｂ、ｃ、ｄ、ｅで括られた各繰り返し単位の存在順序は、式中で限定されない。Ｙは、水素又は炭素数１～４のアルキル基を表す。Ｘ^１は、水素、臭素又はヨウ素を表す。Ｒ^１は、水酸基又は加水分解可能な置換基を表す。Ｒ^２は、水素又は１価の炭化水素基を表す。ｌは、０、１又は２を表す。ｍは１、２又は３を表す。ｎは、１以上の整数を表す。なお、２つの＊は、当該箇所同士で直接結合していることを表している。）

（式（３）中、Ｒｆ^２は、－（Ｃ_ｋＦ_２ｋ）Ｏ－（ｋは１～６の整数）で表される単位を含み、分岐を有しない直鎖状のパーフルオロポリアルキレンエーテル構造を有する２価の基を表す。Ｒ^３は、同一若しくは異なって炭素原子数１～８の１価炭化水素基を表す。Ｘ^２は、同一若しくは異なって加水分解性基又はハロゲン原子を表す。ｓは、同一若しくは異なって０～２の整数を表す。ｔは、同一若しくは異なって１～５の整数を表す。ｈ、ｉは、同一若しくは異なって１、２又は３を表す。） The perfluoroether group-containing silane compound is preferably a compound represented by the following formula (2) or (3).

(In formula (2), Rf ¹ represents a perfluoroalkyl group. Z represents a fluorine or trifluoromethyl group. a, b, c, d, and e are the same or different, and are 0 or 1 or more. represents an integer, a + b + c + d + e is 1 or more, and the order of existence of each repeating unit enclosed by a, b, c, d, and e is not limited in the formula Y is hydrogen or has 1 to 4 carbon atoms represents an alkyl group of X ¹ represents hydrogen, bromine or iodine, R ¹ represents a hydroxyl group or a hydrolyzable substituent, R ² represents hydrogen or a monovalent hydrocarbon group, l represents , 0, 1, or 2. m represents 1, 2, or 3. n represents an integer of 1 or more, and two asterisks (*) indicate that the sites are directly bonded to each other. .)

(In the formula (3), Rf ² is an unbranched linear perfluoropolyalkylene ether containing a unit represented by —(C _k F _2k )O— (k is an integer of 1 to 6). represents a divalent group having a structure, R ³ is the same or different and represents a monovalent hydrocarbon group having 1 to 8 carbon atoms, and X ² is the same or different and represents a hydrolyzable group or a halogen atom s is the same or different and represents an integer of 0 to 2. t is the same or different and represents an integer of 1 to 5. h and i are the same or different and represent 1, 2 or 3.)

In the surface modification method, the length of the modified polymer chain formed is preferably 200-7000 nm.

The present invention relates to a surface-modified elastic body in which at least a portion of a three-dimensional solid surface is modified by the surface modification method.
The present invention relates to a syringe gasket having at least a portion of its surface modified by the surface modification method.

The syringe gasket has the polymer chain immobilized on at least a part of the surface of the base gasket, and has a plurality of annular protrusions on the sliding surface, wherein the annular protrusions include The surface roughness Ra of the first protrusion closest to the surface is preferably 1.0 or less.

The surface roughness Ra is preferably 0.8 or less, more preferably 0.6 or less.
The surface roughness Ra of the base gasket is preferably 1.0 or less, more preferably 0.8 or less, and even more preferably 0.6 or less.

The syringe gasket has the polymer chain immobilized on at least a part of the surface of the base gasket, and has a plurality of annular protrusions on the sliding surface, wherein the annular protrusions include It is preferable that the surface roughness Rz of the first protrusion closest to the surface is 25.0 or less.

The syringe gasket has the polymer chain immobilized on at least a part of the surface of the base gasket, and has a plurality of annular protrusions on the sliding surface, wherein the annular protrusions include It is preferable that the surface roughness Rv of the first protrusion closest to the surface is 21.0 or less.

According to the present invention, since the surface modification method includes steps 1 to 3 or steps I to II, various functionalities such as slidability, liquid leakage resistance, and protein adsorption suppression can be economically achieved. can be given to advantage.

1 is an example of a vertical cross-sectional view showing a base gasket that immobilizes modified polymer chains. FIG. 1 is an example of a vertical cross-sectional view showing a syringe gasket in which modified polymer chains are immobilized on the surface of a base gasket; FIG. FIG. 3 is an example of a partially enlarged view of a first projecting portion of the syringe gasket of FIG. 2;

A first aspect of the present invention is a surface modification method using vulcanized rubber as an object to be modified, comprising a step 1 of forming a polymerization initiation point A on the surface of the object to be modified, and forming the polymerization initiation point A Step 2 of growing a polymer chain by radically polymerizing a monomer using it as a starting point, adding a silane compound to the surface of the polymer chain, and further reacting with at least a silane compound containing a fluoroalkyl group to form a modified polymer chain. and step 3.

In general, in order to form a polymer chain on the surface of vulcanized rubber with large unevenness and provide functionality, a polymer chain having a certain height (length) from the surface is formed, and the functional polymer chain is placed on the surface. However, since functional monomers are usually very expensive, it will be economically disadvantageous unless the amount of polymer chains resulting therefrom is kept to the minimum required for the functionality to be exhibited. In contrast to this, the present invention first forms a polymer chain from a relatively inexpensive monomer on the surface of the object to be modified to build a certain degree of scaffolding, adds a silane compound thereon, and then adds at least This is a surface modification method in which a fluoroalkyl group-containing functional silane compound is formed on the outermost surface by further reacting (addition, etc.) a fluoroalkyl group-containing silane compound to form a modified polymer chain. Therefore, desired functionality can be imparted very economically. Desired performance such as sufficient slidability cannot be obtained only by forming a fluoroalkyl group-containing functional silane compound without forming a relatively inexpensive polymer chain.

Furthermore, by using a modified polymer chain on which a fluoroalkyl group-containing silane compound with low surface free energy is formed on the outermost surface, the object to be modified has excellent slidability, liquid leakage resistance, biocompatibility, Performance such as protein adsorption suppression can be imparted. Although the perfluoroether group also has a low surface free energy, ether oxygen is present, whereas in the present invention, by predominantly imparting oxygen-free fluoroalkyl groups to the surface, more excellent resistance is obtained. It is possible to impart properties such as liquid leakage, biocompatibility, and protein adsorption suppression.

In step 1, a polymerization initiation point A is formed on the surface of vulcanized rubber (object to be modified). As the vulcanized rubber, one having a carbon atom adjacent to a double bond (a carbon atom at the allylic position) is preferably used.

Rubbers to be modified include diene rubbers such as styrene-butadiene rubber, butadiene rubber, isoprene rubber, natural rubber, deproteinized natural rubber, butyl rubber containing several percent of isoprene unit as unsaturation, and halogenated butyl rubber. is mentioned. In the case of butyl rubber and halogenated butyl rubber, triazine-based crosslinked rubber is preferable because it reduces the amount of extractables from the vulcanized rubber. In this case, an acid acceptor may be included, and suitable acid acceptors include hydrotalcite and magnesium carbonate.

For other rubbers, sulfur vulcanization is preferred. In that case, compounding agents such as vulcanization accelerators, zinc oxide, fillers, and silane coupling agents generally used in sulfur vulcanization may be added. Carbon black, silica, clay, talc, calcium carbonate and the like can be suitably used as fillers.

The rubber vulcanization conditions may be appropriately set, 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.

The Shore A hardness of the vulcanized rubber is preferably 50 to 70, more preferably 53 to 65, from the viewpoints of slidability, liquid leakage resistance, protein adsorption inhibition, and the like.
The hardness of the vulcanized rubber is a value measured according to JIS K 6253 with a type A durometer (Shore A) at a temperature of 23°C.

The polymerization initiation point A is formed, for example, by adsorbing the photopolymerization initiator A on the surface of the object to be modified. Examples of the photopolymerization initiator A include carbonyl compounds, organic sulfur compounds such as tetraethylthiuram disulfide, persulfides, redox compounds, azo compounds, diazo compounds, halogen compounds, and photoreducible dyes. , carbonyl compounds are preferred.

As the carbonyl compound as the photopolymerization initiator A, benzophenone and its derivatives (benzophenone-based compounds) are preferred. As the photopolymerization initiator A, a thioxanthone-based compound can also be suitably used because it has a high polymerization rate and easily adsorbs and/or reacts with rubber or the like. Among them, it is preferable to use at least one benzophenone compound. Incidentally, examples of benzophenone-based and thioxanthone-based compounds include compounds described in International Publication No. 2016/042912.

As a method for adsorbing the photopolymerization initiator A such as a benzophenone-based compound and a thioxanthone-based compound to the surface of the object to be modified, the method described in International Publication No. 2016/042912 can be used.

Among them, by treating the surface of the object to be modified with a photopolymerization initiator A, the photopolymerization initiator A is adsorbed on the surface, or by irradiating the treated surface with LED light of 300 to 400 nm. , the polymerization initiation point A can also be formed. In particular, surface treatment with a benzophenone-based compound solution or a thioxanthone-based compound solution is applied to the surface of the object to be modified to adsorb the photopolymerization initiator A, or the surface after further treatment is irradiated with LED light of 300 to 400 nm. , the adsorbed photopolymerization initiator A can be chemically bonded to the surface. If the wavelength is less than 300 nm, the molecules of the object to be modified may be cut and damaged, so light of 300 nm or more is preferable. Light is more preferred. On the other hand, with light exceeding 400 nm, the polymerization initiator is less likely to be activated and the polymerization reaction is less likely to proceed, so light of 400 nm or less is preferable. A wavelength of 355 to 390 nm is particularly suitable for the LED light. In addition, LED light has a narrow wavelength and is suitable in that it does not emit wavelengths other than the center wavelength, but if a mercury lamp or the like is used with a filter to cut light of less than 300 nm, the same effect as LED light can be obtained. is also possible.

In step 2, a monomer is radically polymerized starting from the polymerization initiation point A to grow a polymer chain.

The monomer in step 2 is a monomer that forms a polymer chain that does not have a function that is appropriately set depending on the application. For example, when imparting functions such as slidability, biocompatibility, and antibacterial properties to the object to be modified, monomers that do not impart these functions are suitable, and may be appropriately selected from the viewpoint of economic efficiency.

Monomers may be appropriately selected from the above viewpoints, and examples include acrylic acid, acrylic acid esters (methyl acrylate, ethyl acrylate, etc.), alkali metal acrylate salts (sodium acrylate, potassium acrylate, etc.), acrylic acid Amine salts, acrylamide, dimethylacrylamide, diethylacrylamide, isopropylacrylamide, hydroxyethylacrylamide, acryloylmorpholine, methoxymethyl acrylate, hydroxyethyl acrylate, methacrylic acid, methacrylic acid esters (methyl methacrylate, ethyl methacrylate, etc.), alkali metal methacrylates Salt (sodium methacrylate, potassium methacrylate, etc.), methacrylic acid amine salt, methacrylamide, dimethylmethacrylamide, diethylmethacrylamide, isopropylmethacrylamide, hydroxyethylmethacrylamide, methacryloylmorpholine, methoxymethylmethacrylate, hydroxyethylmethacrylate, acrylonitrile, etc. can be used. These may be used alone or in combination of two or more. Among them, (meth)acrylic acid and (meth)acrylamide are preferable, and it is more preferable to use (meth)acrylic acid and (meth)acrylamide together.

The method of radical polymerization of the monomer in step 2, the amount of monomer used, the coating (spraying) solvent, the coating (spraying) method, the immersion method, the irradiation conditions, etc. are the methods described in International Publication No. 2016/042912. can be used. A monomer (liquid) and its solution containing a known polymerization inhibitor such as 4-methylphenol can also be used.

In the present invention, radical polymerization of the monomer proceeds by applying the monomer (liquid) or its solution, or after immersion in the monomer or its solution, pulling it up as necessary, drying it, and irradiating it with light. UV irradiation light sources such as high-pressure mercury lamps, metal halide lamps, and LED lamps having an emission wavelength in ultraviolet light can be preferably used. The amount of irradiation light may be appropriately set in consideration of the polymerization time and the uniformity of progress of the reaction. Moreover, in order to prevent polymerization inhibition by an active gas such as oxygen in the reaction vessel, oxygen is preferably removed from the reaction vessel or the reaction solution during or before the light irradiation. Therefore, an inert gas such as nitrogen gas or argon gas is introduced into the reaction vessel or the reaction solution, the active gas such as oxygen is discharged out of the reaction system, and the inside of the reaction system is replaced with an inert gas atmosphere. Evacuating the inside of the reaction vessel to deaerate oxygen is performed as appropriate. Furthermore, in order to prevent oxygen from inhibiting the reaction, the UV irradiation light source is installed at a position where an air layer (oxygen content of 15% or more) does not enter between the reaction container made of glass or plastic, the reaction solution, or the object to be modified. Such measures are also taken as appropriate.

When irradiating ultraviolet rays, the wavelength is preferably 300 to 400 nm. Thereby, a polymer chain can be favorably formed on the surface of the object to be modified. A high-pressure mercury lamp, an LED with a central wavelength of 365 nm, an LED with a central wavelength of 375 nm, or the like can be used as the light source. Among them, it is preferable to irradiate with LED light of 355 to 390 nm. In particular, an LED having a center wavelength of 365 nm, which is close to the excitation wavelength of 366 nm of benzophenone, is preferable in terms of efficiency.

In step 3, a modified polymer chain is formed (prepared) by adding a silane compound to the surface of the polymer chain and reacting it with a silane compound containing a fluoroalkyl group. As a result, a modified polymer chain is formed in which the fluoroalkyl group-containing functional silane compound is added to the surface of the polymer chain, and the desired performance is imparted.

Although the silane compound is not particularly limited, a silane compound having no fluoroalkyl group or the like can be used. Among them, alkoxysilanes and modified alkoxysilanes are preferred, and alkoxysilanes are more preferred, from the viewpoint that the effects of the present invention can be obtained more favorably. The silane compounds may be used alone or in combination of two or more.

Alkoxysilanes include monoalkoxysilanes such as trimethylmethoxysilane, triethylethoxysilane, tripropylpropoxysilane and tributylbutoxysilane; dialkoxysilanes such as dimethyldimethoxysilane, diethyldiethoxysilane, dipropyldipropoxysilane and dibutyldibutoxysilane; Silane; trialkoxysilane such as methyltrimethoxysilane, ethyltriethoxysilane, propyltripropoxysilane, butyltributoxysilane; tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, dibutoxydiethoxysilane, butoxysilane Examples include tetraalkoxysilanes such as triethoxysilane and ethoxytriethoxysilane. These may be used alone or in combination of two or more. Among these, tetraalkoxysilanes are preferable because the effects of the present invention can be obtained more favorably, and tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, dibutoxydiethoxysilane, butoxytriethoxysilane, and ethoxytributoxysilane. is more preferred.

The modified alkoxysilane is an alkoxysilane having a substituent such as an amino group, a carboxyl group, a hydroxyl group, an epoxy group, and at least one selected from the group consisting of an alkyl group, an amino group, a carboxyl group, a hydroxyl group and an epoxy group. It is preferable to have

Alkoxysilanes and modified alkoxysilanes preferably have 4 to 22 carbon atoms, more preferably 4 to 16 carbon atoms, from the viewpoint that the effects of the present invention can be obtained more satisfactorily.

Tetraalkoxysilanes and modified alkoxysilanes preferably have at least one selected from the group consisting of a methoxy group, an ethoxy group, a propoxy group and a butoxy group, from the viewpoint that the effects of the present invention can be obtained more favorably. It is more preferable to have an ethoxy group and/or a butoxy group, and it is still more preferable to have an ethoxy group and a butoxy group.

（式中、平均値として、ｍ＋ｎ＝４、ｎ＞ｍ＞０である。） Commercially available silane compounds include Primercoat PC-3B (manufactured by Fluoro Technology Co., Ltd., butoxy/ethoxy tetraalkoxysilane represented by the following formula).

(In the formula, m+n=4 and n>m>0 as average values.)

In step 3, the method of adding the silane compound to the surface of the polymer chain is not particularly limited, and for example, a conventionally known method such as a method of contacting an object to be modified on which the polymer chain is formed is brought into contact with the silane compound. Any method can be adopted as appropriate.

In step 3, after adding the silane compound to the surface of the polymer chain, at least the fluoroalkyl group-containing silane compound is reacted to form a modified polymer chain.

Examples of the fluoroalkyl group in the fluoroalkyl group-containing silane compound include groups represented by the following formulae.

In the above formula, n is preferably 1-5, more preferably 3-5. m is preferably 1 to 6, more preferably 2 to 6. Also, 0≦m+n≦10 is preferable, and 0≦m+n≦7 is more preferable.

Specific fluoroalkyl groups include 3,3,3-trifluoropropyl group, 3,3,4,4,4-pentafluorobutyl group, 3,3,4,4,5,5,6,6 ,6-nonafluorohexyl group, 3,3,4,4,5,5,6,6,7,7,7-undecafluoroheptyl group, 3,3,4,4,5,5,6, 6,7,7,8,8,8-tridecafluorooctyl group and the like.

The fluoroalkyl group-containing silane compound is not particularly limited, but from the viewpoint of economically imparting various functions such as slidability, liquid leakage resistance, and protein adsorption inhibition, compounds represented by the following formula (1) can be preferably used.

In formula (1), n is preferably 1-5, more preferably 3-5. m is preferably 1 to 6, more preferably 2 to 6. Also, 0≦m+n≦10 is preferable, and 0≦m+n≦7 is more preferable. R ¹ (alkyl group) may be linear, branched, cyclic, or a combination of two or more of these structures. The number of carbon atoms in R ¹ is preferably 1-10, preferably 1-5, more preferably 1-3. Examples of alkyl groups for R ¹ include methyl, ethyl, and propyl groups.

Specific examples of the fluoroalkyl group-containing silane compound represented by the formula (1) include 3,3,3-trifluoropropyltrimethoxysilane, 3,3,3-trifluoropropyltriethoxysilane, 3,3 , 4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyltrimethoxysilane and the like. These can be used singly or in combination of two or more.

In step 3, the method of reacting (adding) the polymer chain to which the silane compound is added and the fluoroalkyl group-containing silane compound is not particularly limited. A conventionally known method such as a method of contacting an object to be modified to which a silane compound has been added can be appropriately employed. The solution of the fluoroalkyl group-containing silane compound is prepared by using a known solvent capable of dissolving the compound, such as water, perfluorohexane, acidic water, methanol, ethanol, or a mixture of water and methanol or ethanol, and adjusting the concentration appropriately. Can be adjusted and made. Any contact method such as coating, spraying (spraying), or immersion can be employed as the contact method.

The reaction between the silane compound-added polymer chain and the fluoroalkyl group-containing silane compound is preferably maintained at a humidity of 50% or more after contact such as immersion as described above. Thereby, the reaction proceeds more and the effects of the present invention can be obtained favorably. The humidity is more preferably 60% or higher, and even more preferably 80% or higher. Although the upper limit is not particularly limited, for example, 100% or less is preferable. Moreover, the holding time and temperature may be appropriately set, and for example, 0.5 to 60 hours and 20 to 120° C. are preferable.

In step 3, after the silane compound is added to the surface of the polymer chain, the perfluoroether group-containing silane compound is further added in addition to the fluoroalkyl group-containing silane compound, since the effect of the present invention can be favorably obtained. are also reacted (added) to form modified polymer chains.

The perfluoroether group-containing silane compound is not particularly limited as long as it is a silane compound having a perfluoroether group. For example, a compound represented by the following formula (2) or (3) can be preferably used.

（式（２）中、Ｒｆ^１は、パーフルオロアルキル基を表す。Ｚは、フッ素又はトリフルオロメチル基を表す。ａ、ｂ、ｃ、ｄ、ｅは、同一若しくは異なって、０又は１以上の整数を表し、ａ＋ｂ＋ｃ＋ｄ＋ｅは、１以上であり、ａ、ｂ、ｃ、ｄ、ｅで括られた各繰り返し単位の存在順序は、式中で限定されない。Ｙは、水素又は炭素数１～４のアルキル基を表す。Ｘ^１は、水素、臭素又はヨウ素を表す。Ｒ^１は、水酸基又は炭素数１～４のアルコキシ基等の加水分解可能な置換基を表す。Ｒ^２は、水素又は１価の炭化水素基を表す。ｌは、０、１又は２を表す。ｍは１、２又は３を表す。ｎは、１以上の整数を表す。なお、２つの＊は、当該箇所同士で直接結合していることを表している。）

(In formula (2), Rf ¹ represents a perfluoroalkyl group. Z represents a fluorine or trifluoromethyl group. a, b, c, d, and e are the same or different, and are 0 or 1 or more. represents an integer, a + b + c + d + e is 1 or more, and the order of existence of each repeating unit enclosed by a, b, c, d, and e is not limited in the formula Y is hydrogen or has 1 to 4 carbon atoms X ¹ represents hydrogen, bromine or iodine, R ¹ represents a hydrolyzable substituent such as a hydroxyl group or an alkoxy group having 1 to 4 carbon atoms, R ² represents hydrogen or 1 represents a valent hydrocarbon group, l represents 0, 1 or 2, m represents 1, 2 or 3, n represents an integer of 1 or more, and two * represent It indicates a direct connection.)

（式（３）中、Ｒｆ^２は、－（Ｃ_ｋＦ_２ｋ）Ｏ－（ｋは１～６の整数）で表される単位を含み、分岐を有しない直鎖状のパーフルオロポリアルキレンエーテル構造を有する２価の基を表す。Ｒ^３は、同一若しくは異なって炭素原子数１～８の１価炭化水素基を表す。Ｘ^２は、同一若しくは異なって炭素数１～４のアルコキシ基等の加水分解性基又はハロゲン原子を表す。ｓは、同一若しくは異なって０～２の整数を表す。ｔは、同一若しくは異なって１～５の整数を表す。ｈ、ｉは、同一若しくは異なって１、２又は３を表す。）

(In the formula (3), Rf ² is an unbranched linear perfluoropolyalkylene ether containing a unit represented by —(C _k F _2k )O— (k is an integer of 1 to 6). represents a divalent group having a structure, wherein R ³ is the same or different and represents a monovalent hydrocarbon group having 1 to 8 carbon atoms, X ² is the same or different and represents an alkoxy group having 1 to 4 carbon atoms, etc. represents a hydrolyzable group or a halogen atom, s is the same or different and represents an integer of 0 to 2, t is the same or different and represents an integer of 1 to 5, h and i are the same or different, represents 1, 2 or 3.)

Here, Rf ¹ in formula (2) is not particularly limited as long as it is a perfluoroalkyl group constituting a general organic-containing fluoropolymer. things are mentioned. Among them, CF ₃ -, C ₂ F ₅ - and C ₃ F ₇ - are preferred.

a, b, c, d, and e in formula (2) represent the number of repeating units of the perfluoropolyether chain that constitutes the main skeleton of the fluorine-containing silane compound, and are each independently preferably 0 to 200, and 0 ~50 is more preferred. Further, a+b+c+d+e (the sum of a to e) is preferably 1-100. The order of existence of the repeating units enclosed by a, b, c, d, and e is described in this order in formula (2), but the order of bonding of these repeating units is in this order. There is no limitation, and any order may be used.

Examples of the alkyl group having 1 to 4 carbon atoms represented by Y in formula (2) include methyl group, ethyl group, propyl group and butyl group, and may be linear or branched. When ^X1 is bromine or iodine, the fluorine-containing silane compound is likely to form a chemical bond.

The hydrolyzable substituent represented by R ¹ in formula (2) is not particularly limited, but is halogen, —OR ⁴ , —OCOR ⁴ , —OC(R ⁴ )=C(R ⁵ ) ₂ , —ON=C (R ⁴ ) ₂ , -ON=CR ⁶ and the like are preferred. Here, R ⁴ is an aliphatic hydrocarbon group or an aromatic hydrocarbon group, R ⁵ is hydrogen or an aliphatic hydrocarbon group having 1 to 4 carbon atoms, and R ⁶ is a divalent aliphatic hydrocarbon group having 3 to 6 carbon atoms. represents a hydrogen group. More preferred are chlorine, —OCH ₃ and —OC ₂ H ₅ . Also, the monovalent hydrocarbon group represented by R ² is not particularly limited, but is preferably a methyl group, an ethyl group, a propyl group, a butyl group, or the like, and may be linear or branched.

l in formula (2) represents the number of carbon atoms in the alkylene group present between the carbon atoms constituting the perfluoropolyether chain and the silicon atoms bonded thereto, and is preferably zero. m represents the number of bonds of the substituent ^R1 bonded to silicon, and ^R2 bonds to the silicon in the portion to which the ^R1 is not bonded. Although the upper limit of n is not particularly limited, it is preferably an integer of 1-10.

On the other hand, the group represented by Rf ² in formula (3) is not particularly limited, but when each s is 0, the terminal of the Rf ² group bonded to the oxygen atom in formula (3) should not be an oxygen atom. preferable. Further, k in Rf ² is preferably an integer of 1 to 4. Specific examples of the group represented by Rf ² include -CF ₂ CF ₂ O(CF ₂ CF ₂ CF ₂ O) _j CF ₂ CF ₂ - (wherein j is 1 or more, preferably 1 to 50 , more preferably an integer of 10 to 40), -CF ₂ (OC ₂ F ₄ ) _p -(OCF ₂ ) _q - (wherein p and q are each 1 or more, preferably 1 to 50, More preferably an integer of 10 to 40, and the sum of p + q is an integer of 10 to 100, preferably 20 to 90, more preferably 40 to 80, and the repeating units (OC ₂ F ₄ ) and The arrangement of (OCF ₂ ) is random).

R ³ in formula (3) is preferably a monovalent hydrocarbon group having 1 to 8 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl and octyl. cycloalkyl groups such as cyclopentyl group and cyclohexyl group; aryl groups such as phenyl group, tolyl group and xylyl group; aralkyl groups such as benzyl group and phenethyl group; vinyl group, aryl group, butenyl group and pentenyl and alkenyl groups such as hexenyl group. Among them, a methyl group is preferred.

Examples of hydrolyzable groups represented by X ² in formula (3) include alkoxy groups such as methoxy, ethoxy, propoxy and butoxy; alkoxyalkoxy groups such as methoxymethoxy, methoxyethoxy and ethoxyethoxy; alkenyloxy groups such as allyloxy group and isopropenoxy group; acyloxy groups such as acetoxy group, propionyloxy group, butylcarbonyloxy group and benzoyloxy group; dimethylketoxime group, methylethylketoxime group, diethylketoxime group and cyclopennoxime group , a ketoxime group such as a cyclohexanoxime group; N-methylamino group, N-ethylamino group, N-propylamino group, N-butylamino group, N,N-dimethylamino group, N,N-diethylamino group, N -amino groups such as cyclohexylamino group; amide groups such as N-methylacetamide group, N-ethylacetamide group and N-methylbenzamide group; amino groups such as N,N-dimethylaminooxy group and N,N-diethylaminooxy group An oxy group and the like can be mentioned. Further, the halogen atom represented by ^X2 includes a chlorine atom, a bromine atom, an iodine atom and the like. Among them, a methoxy group, an ethoxy group, an isopropenoxy group and a chlorine atom are preferable.

As for s of Formula (3), 1 is preferable and as for t, 3 is preferable. h and i are preferably 3 from the viewpoint of hydrolyzability.

Examples of perfluoroether group-containing silane compounds include compounds represented by the following formula (4).

（式（４）中、Ｒｆ^３は、－（Ｃ_ｋＦ_２ｋ）Ｏ－（ｋは１～６の整数）で表される単位を含み、分岐を有しない直鎖状のパーフルオロポリアルキレンエーテル構造を有する１価の基を表す。Ｒ^３は、同一若しくは異なって炭素原子数１～８の１価炭化水素基を表す。Ｘ^２は、同一若しくは異なって炭素数１～４のアルコキシ基等の加水分解性基又はハロゲン原子を表す。ｓは、同一若しくは異なって０～２の整数を表す。ｔは、同一若しくは異なって１～５の整数を表す。ｉは、同一若しくは異なって１、２又は３を表す。）

(In formula (4), Rf ³ is an unbranched linear perfluoropolyalkylene ether containing a unit represented by —(C _k F _2k )O— (k is an integer of 1 to 6). represents a monovalent group having a structure, wherein R ³ is the same or different and represents a monovalent hydrocarbon group having 1 to 8 carbon atoms, X ² is the same or different and represents an alkoxy group having 1 to 4 carbon atoms, etc. represents a hydrolyzable group or a halogen atom, s is the same or different and represents an integer of 0 to 2, t is the same or different and represents an integer of 1 to 5, i is the same or different and 1, 2 or 3.)

The group represented by Rf ³ in formula (4) is not particularly limited, but when s is 0, the end of the Rf ³ group bonded to the oxygen atom in formula (4) is preferably not an oxygen atom. Further, k in Rf ³ is preferably an integer of 1 to 4. Specific examples of the group represented by Rf ³ include CF ₃ CF ₂ O(CF ₂ CF ₂ CF ₂ O) _j CF ₂ CF ₂ — (wherein j is 1 or more, preferably 1 to 50, more preferably an integer of 10 to 40), CF ₃ (OC ₂ F ₄ ) _p —(OCF ₂ ) _q — (wherein p and q are each 1 or more, preferably 1 to 50, more preferably is an integer of 10 to 40, and the sum of p + q is an integer of 10 to 100, preferably 20 to 90, more preferably 40 to 80, and the repeating units (OC ₂ F ₄ ) and (OCF ₂ ) The sequence is random).

Examples of R ³ in formula (4) include those similar to R ³ in formula (3). Examples of X ² in formula (4) include those similar to X ² in formula (3). As for s of Formula (4), 1 is preferable and as for t, 3 is preferable. i in formula (4) is preferably 3 from the viewpoint of hydrolyzability.

The average molecular weight of the perfluoroether group-containing silane compound is preferably in the range of 1,000 to 10,000 from the standpoint of durability of the release action. The average molecular weight can be measured by standard polystyrene conversion using gel permeation chromatography (GPC).

Commercially available perfluoroether group-containing silane compounds include OPTOOL DSX (manufactured by Daikin Industries, Ltd.), KY-108, KY-164 (manufactured by Shin-Etsu Chemical Co., Ltd.), Fluorolink S10 (Solvay Specialty Polymers Japan ( Co., Ltd.), Novec 2702, Novec 1720 (manufactured by 3M Japan Co., Ltd.), Fluorosurf series such as Fluorosurf FG-5080SH (manufactured by Fluoro Technology Co., Ltd.), SIP6720.72 (manufactured by Gelest, [Perfluoro (polypropyleneoxy)] methoxypropyltrimethox y silane _{, CF3CF2CF2O ( CF2CF2CF2O ) nCH2OCH2CH2CH2Si ( OCH3 ) 3 ) ) .}

The method for further reacting (adding) the perfluoroether group-containing silane compound in Step 3 is not particularly limited. and a solution containing a perfluoroether group-containing silane compound can be used in a similar manner.

In step 3, the mixing ratio of the fluoroalkyl group-containing silane compound and the perfluoroether group-containing silane compound (fluoroalkyl group-containing silane compound:perfluoroether group-containing silane compound (mass ratio)) is 50:50 to 100:0 is preferred, 60:40 to 90:10 is more preferred, and 65:35 to 85:15 is even more preferred, from the viewpoint of imparting various functionalities such as properties and protein adsorption inhibitory properties.

A second aspect of the present invention is a surface modification method using a vulcanized rubber as a modification target, wherein a monomer is radically polymerized on the surface of the modification target in the presence of a photopolymerization initiator A to form a polymer chain. and step II of adding a silane compound to the surface of the polymer chain and reacting it with at least a silane compound containing a fluoroalkyl group to form a modified polymer chain.

Specifically, a monomer is radically polymerized using a photopolymerization initiator A as an initiator to prepare a polymer chain, then a silane compound is added to the obtained polymer chain, and at least a fluoroalkyl compound is added to the surface of the silane compound. It is a surface modification method for forming a fluoroalkyl group-containing functional silane compound on the outermost surface by reacting (adding, etc.) a group-containing silane compound to form a modified polymer chain. Therefore, the desired functionality can be imparted very economically, and at least the fluoroalkyl group-containing functional silane compound is bonded to the outermost surface to provide excellent slidability, liquid leakage resistance, biocompatibility, and protein adsorption. Desired performance such as inhibitory properties can be imparted.

In step I, a monomer is radically polymerized starting from a polymerization initiation point A formed from a photopolymerization initiator A on the surface of the object to be modified to grow a polymer chain, and in step II, a silane is added to the surface of the polymer chain. It is preferable to add a compound and further react at least a fluoroalkyl group-containing silane compound to add a functional silane compound to produce a modified polymer chain. For example, in step I, a photopolymerization initiator A and a monomer are brought into contact with the surface of the object to be modified, and then LED light of 300 to 400 nm is irradiated to remove the polymerization initiation point A from the photopolymerization initiator A. In step II, a silane compound is brought into contact with the surface of the polymer chain, and at least a fluoroalkyl group is formed on the surface of the silane compound. It can be carried out by forming a fluoroalkyl group-containing functional silane compound on the outermost surface by reacting (adding, etc.) the containing silane compound.

The radical polymerization method, the coating (spraying) solvent, the coating (spraying) method, the immersion method, the irradiation conditions, etc. for each of the monomers in step I can use the methods described in WO 2016/042912. .

As the method of reaction (addition, etc.) of the silane compound and the fluoroalkyl group-containing silane compound in Step II, the same method as in Step 3 can be applied.

In Step II, since the effect of the present invention is favorably obtained, after adding the silane compound to the surface of the polymer chain, the silane compound containing the fluoroalkyl group and the silane compound containing the perfluoroether group are further added. It is preferred that the compounds also react (add) to form modified polymer chains. In addition, the method of reacting (adding) can be carried out by the same method as described above. In step I, the preferred mixing ratio of the fluoroalkyl group-containing silane compound and the perfluoroether group-containing silane compound is the same as described above.

The length of the modified polymer chain formed (total thickness (graft chain + silane compound + fluoroalkyl group-containing silane compound)) is preferably 200 to 7000 nm, more preferably 500 to 3000 nm. If it is less than 200 nm, there is a tendency that good slidability cannot be obtained. If it exceeds 7000 nm, further improvement in slidability cannot be expected, and raw material costs tend to increase due to the use of expensive monomers, and the surface pattern due to surface treatment becomes visible with the naked eye, resulting in aesthetic appearance. and the sealing property tends to deteriorate.

In steps 2 and I, two or more monomers may be radically polymerized at the same time starting from the polymerization initiation point A. In the above step 3 and step II, two or more silane compounds may be added at the same time, and two or more fluoroalkyl group-containing silane compounds and perfluoroether group-containing silane compounds are simultaneously reacted on the surface of the obtained silane compound. You may let Further, the polymer chain, the silane compound, etc. may each be laminated in two or more layers. Furthermore, multiple polymer chains may be grown on the surface of the object to be modified. The surface modification method of the present invention may crosslink between polymer chains. In this case, ionic cross-linking, cross-linking by a hydrophilic group having an oxygen atom, cross-linking by a halogen group such as iodine, cross-linking by UV, electron beam, γ-ray or the like may be formed between polymer chains.

By applying the surface modification method to vulcanized rubber, a surface-modified elastic body can be obtained. For example, a surface-modified elastic body having excellent slidability in the presence of water or in a dry state can be obtained, which is also excellent in terms of low friction and low water resistance. Further, by applying the above method to at least part of a three-dimensional solid (elastic body, etc.), a modified surface-modified elastic body can be obtained. Furthermore, preferred examples of the surface-modified elastic body include polymer brushes (polymer brushes). Here, the polymer brush means a graft polymer grafting from surface-initiated living radical polymerization. In addition, it is preferable that the grafted chains are oriented in a direction substantially perpendicular to the surface of the object to be modified, because entropy is reduced and the molecular motion of the grafted chains is reduced, thereby obtaining slidability. Furthermore, semi-density and density brushes having a brush density of 0.01 chains/nm ² or more are preferred.

In addition, by applying the surface modification method to vulcanized rubber, a syringe gasket having at least a part of the modified surface can be manufactured. The modification is preferably applied to at least the sliding portion of the gasket surface, and may be applied to the entire surface.

The syringe gasket is a syringe gasket in which the polymer chains are immobilized on at least a part of the base gasket surface and a plurality of annular protrusions on the sliding surface, wherein the annular protrusions include A syringe gasket in which the surface roughness Ra of the first protrusion closest to the surface is 1.0 or less is preferable. By fixing the modified polymer chain on the base material surface and adjusting the surface roughness Ra of at least the first protrusion closest to the top surface to 1.0 or less, the slidability and liquid leakage resistance are improved. dimensionally compatible.

FIG. 1 is an example of a longitudinal sectional view (sectional view in the sliding direction (vertical sectional view)) showing a substrate 1 (base gasket 1) on which modified polymer chains are immobilized. FIG. 2 is an example of a vertical cross-sectional view of a syringe gasket 2 in which modified polymer chains 21 are immobilized on the surface of the base gasket 1 of FIG. FIG. 3 is an example of a partially enlarged view (encircled portion) of the first projecting portion 14a of the syringe gasket 2 of FIG.

The syringe gasket 2 is used for a syringe or the like that includes a barrel for injecting a liquid, a plunger for pushing out the liquid injected into the barrel, and a gasket attached to the tip of the plunger.

The syringe gasket 2 of FIG. 2 is obtained by immobilizing a modified polymer chain on at least a part of the sliding surface of the base gasket 1 of FIG. The syringe gasket 2, which has a base gasket 1 in a straight body shape and a modified polymer chain 21 fixed thereto, has a top surface portion 12 on the liquid contact side and a bottom surface portion 13 that is joined to the tip of the plunger. It is formed integrally with a sliding portion 14 (body portion) extending in the width direction (sliding direction).

On the outer peripheral surface of the sliding portion 14 of the base gasket 1 and the syringe gasket 2, there are three annular protrusions that are in sliding contact with the inner peripheral surface of the peripheral body portion of the barrel, that is, the third annular protrusions arranged at the closest position from the top surface portion 12. 1 protruding portion 14a (first protruding portion 14a closest to the top surface), bottom-side protruding portion 14c located farthest from the top surface portion 12 (bottom-side protruding portion 14c closest to the bottom surface), between 14a and 14c is provided with an intermediate protruding portion 14b. In the base gasket of FIG. 1, the top surface portion 12 and the first projecting portion 14a are integrally formed.

Although FIGS. 1 and 2 show a form having three annular projections, the number is not particularly limited as long as the number is two or more. Also, although a mode having one intermediate protrusion 14b is shown, all the protrusions located between the first protrusion and the bottom side protrusion correspond to intermediate protrusions, and a plurality of intermediate protrusions are included. may have.

From the viewpoint of achieving both slidability and liquid leakage resistance, it is preferable that the syringe gasket 2 has three or more annular protrusions. In the base gasket 1 and the syringe gasket 2, which have a straight barrel shape, a top surface portion 12 on the liquid contact side, a bottom surface portion 13 joined to the tip portion of the plunger, a first projection portion 14a, an intermediate projection portion 14b, and a bottom surface side projection. The shape of the portion 14c and the sliding portion 14 is not particularly limited.

The syringe gasket 2 shown in FIGS. 2 and 3 (partially enlarged view of the first projecting portion 14a) has a modified polymer chain 21 immobilized on at least a part of the surface of the base gasket 1. Here, An example is shown in which the modified polymer chain 21 is fixed to the entire sliding portion 14 (trunk portion) including the top surface portion 12 and the annular projections (the first projection 14a, the intermediate projection 14b, and the bottom projection 14c). ing.

In the syringe gasket 2 (after the modified polymer chains are fixed), the surface roughness Ra of the first projecting portion 14a on which the modified polymer chains 21 are formed is 1 in order to achieve both slidability and liquid leakage resistance. 0.0 or less is preferable, 0.8 or less is more preferable, and 0.6 or less is even more preferable. The lower limit is not particularly limited, and the smaller the better.
In this specification, the surface roughness Ra is the arithmetic mean height Ra defined by JIS B 0601-2001 and ISO 4287-1997.

The surface roughness Ra of the first projections 14a in the base gasket 1 (before immobilization of the modified polymer chains) is preferably 1.0 or less, more preferably 1.0 or less, more preferably It is 0.8 or less, more preferably 0.6 or less. The lower limit is not particularly limited, and the smaller the better.

In the syringe gasket 2 (after the modified polymer chains are fixed), the surface roughness Rz of the first projecting portion 14a on which the modified polymer chains 21 are formed is 25 from the viewpoint of compatibility between slidability and liquid leakage resistance. 0.0 or less is preferable, 22.0 or less is more preferable, and 20.0 or less is even more preferable. The lower limit is not particularly limited, and the smaller the better.
In this specification, the surface roughness Rz is the maximum height Rz defined by JIS B 0601-2001 and ISO 4287-1997.

In the syringe gasket 2 (after the modified polymer chains are fixed), the surface roughness Rv of the first projecting portion 14a on which the modified polymer chains 21 are formed is 21 in order to achieve both slidability and liquid leakage resistance. .0 or less is preferable, 18.0 or less is more preferable, and 16.5 or less is even more preferable. The lower limit is not particularly limited, and the smaller the better.
In this specification, the surface roughness Rv is the maximum valley depth Rv defined by JIS B 0601-2001 and ISO 4287-1997.

The surface roughness Ra of the base gasket 1 and the syringe gasket 2 to which the modified polymer chains 21 are immobilized can be adjusted by changing the surface roughness of the molding die. Specifically, it can be adjusted by changing the particle size of the polishing agent used in the final polishing step when manufacturing the mold. Examples of abrasives include abrasive grains such as diamond, alumina, silicon carbide, cubic boron nitride, boron carbide, zirconium oxide, manganese oxide, and colloidal silica. 100 or the like can be preferably used.

As a material for the molding die, known materials can be used, such as carbon steel and precipitation stainless steel. The mold for molding can be manufactured using a cutting method such as a method of cutting a cemented carbide tool, a coated cemented carbide, a cBN sintered body, or the like, followed by grinding and polishing.

The surface roughnesses Rz and Rv of the syringe gasket 2 to which the modified polymer chains 21 are immobilized are determined by the drying method after reacting the fluoroalkyl group-containing silane compound and then washing with a solvent such as acetone. Adjustable. Specifically, if only the modified polymer chain is rapidly dried after washing, the surface tends to crack and Rz and Rv tend to increase. Rz and Rv are reduced by gradually drying using the above-described Rz and Rv.

EXAMPLES The present invention will be specifically described based on Examples, but the present invention is not limited to these.

The vulcanized rubber (base gasket: form shown in FIG. 1) used in the following examples and comparative examples was prepared by cross-linking chlorobutyl rubber (degree of unsaturation: 1 to 2%) containing isoprene units with triazine ( vulcanization at 180°C for 10 minutes). At that time, by adjusting the amount of the filler and the amount of triazine, gaskets having a shear A hardness of 47, 50.5, 54, 57, 63 and 72 were produced (hardness measurement method is as follows).
Since it was difficult to measure the hardness of vulcanized rubber (base gasket), we prepared a sheet vulcanized rubber with the same compounding and vulcanization conditions, measured its hardness, and compared it with the hardness of the base gasket. (The hardness of the base gasket can be considered to be the same).

[Hardness of vulcanized rubber (base gasket)]
The hardness (Shore A) of the vulcanized rubber (base gasket) at 23° C. was measured with a type A durometer according to JIS K6253 “Vulcanized rubber and thermoplastic rubber—Determination of hardness”.

(Example 1)
A vulcanized rubber (base gasket) was immersed in a 1 wt % acetone solution of benzophenone to adsorb benzophenone on the surface of the vulcanized rubber, followed by drying. Dried vulcanized rubber (base gasket) was placed in a glass containing a 25:75 mixed aqueous solution of acrylic acid and acrylamide (2.5 M: 4.5 g of acrylic acid and 13.4 g of acrylamide dissolved in 100 mL of water). It was immersed in a reaction vessel and irradiated with an LED-UV light having a wavelength of 365 nm for 50 minutes for radical polymerization to grow polymer chains on the rubber surface. After that, the surface was washed with water and dried.
After that, it was immersed in a 1 wt % butanol solution of a silane compound (Primer Coat PC-3B (butoxy/ethoxy tetraalkoxysilane represented by the above formula, manufactured by Fluoro Technology Co., Ltd.)) and pulled out. After that, it was allowed to react at 100° C. for 2 hours under a humidity of 90%. The surface was washed with acetone and water and dried.
Then, the dried vulcanized rubber (base gasket) was coated with a silane compound containing a fluoroalkyl group represented by the following formula (triethoxy-1H,1H,2H,2H-tridecafluoro-n-octylsilane: T1770 manufactured by Tokyo Chemical Industry Co., Ltd.; Fluoroalkyl group: CF ₃ (CF ₂ ) ₅ (CH ₂ ) ₂ —) and a perfluoroether group-containing silane compound (manufactured by Daikin Industries, Ltd., OPTOOL DSX-E, compound of formula (2) above) It was immersed in a 2% perfluorohexane solution of 75:25 (mass ratio) and pulled up. After that, it was allowed to react at 70° C. for 8 hours under a humidity of 90%. After that, it was washed with acetone and dried. A surface-modified elastic body was thus obtained.

(Examples 2 to 17 and Comparative Example 2)
Example 1 except that the hardness of the vulcanized rubber (base gasket), the mixing ratio of acrylic acid and acrylamide, and the mixing ratio of the fluoroalkyl group-containing silane compound and the perfluoroether group-containing silane compound were changed as shown in Table 1. A surface-modified elastic body was obtained in the same manner as above.

(Example 18)
A surface-modified elastic body was obtained in the same manner as in Example 15, except that the fluoroalkyl group-containing silane compound was changed to CF ₃ (CF ₂ ) ₃ CH ₂ CH ₂ Si(OCH ₂ CH ₃ ) ₃ .

(Comparative example 1)
A vulcanized rubber obtained by cross-linking chlorobutyl rubber (unsaturation: 1 to 2%) containing an isoprene unit with triazine (vulcanization at 180°C for 10 minutes (base gasket)) itself was used (Shore A hardness: 50.5 ).

In Examples 4 and 17 in Table 2, the fluoroalkyl group-containing silane compound was reacted (added), washed with acetone, and then dried naturally under normal pressure for 2 hours or more in the drying step, and then placed in an oven. After the temperature was raised to 120° C. over 2 hours or more, vacuuming was started and the film was held for 1 hour for drying.

The surface-modified elastic bodies produced in Examples and Comparative Examples were evaluated by the following methods.

[Surface roughness Ra, Rz, Rv]
Ra (arithmetic mean height), Rz (maximum height) and Rv (maximum valley depth) were measured.

[Length of modified polymer chain (total polymer chain)]
The length of the modified polymer chain formed on the surface of the vulcanized rubber was measured using an SEM on the cross section of the modified rubber on which the modified polymer chain was formed, at an accelerating voltage of 15 kV and 1000 times. The thickness of the photographed polymer layer was taken as the length of the modified polymer chain.

[Sliding property (frictional resistance)]
In order to measure the frictional resistance of the surface of the surface-modified elastic body, the vulcanized rubber (base gasket) prepared in Examples and Comparative Examples was set in a COP resin syringe of a syringe and pushed in using a tensile tester. Then, the frictional resistance was measured (indentation speed: 30 mm/min). Taking the frictional resistance index of Comparative Example 1 as 100, the following formula was used to show the frictional resistance index for each example. A smaller index indicates a lower frictional resistance and better slidability.
(Frictional resistance index) = Frictional resistance of each example/Frictional resistance of Comparative Example 1 × 100

[Leak resistance]
The vulcanized rubber gaskets prepared in Examples and Comparative Examples were set in a COP resin syringe of a syringe, an aqueous food coloring solution was added, the cap was put on, and stored at 40°C for 2 weeks, and the state of liquid leakage was visually confirmed. , was evaluated in four stages.
⊚: No food coloring red (pink) stains on the first projecting portion closest to the top surface.
◯: Slight red (pink) stains of food coloring were observed above the half of the first protrusion closest to the top surface.
Δ: Red (pink) stains of food coloring were observed to the bottom of the first projecting portion closest to the top surface.
x: A red (pink) stain of food coloring was observed beyond the first protruding portion closest to the top surface.

[Protein adsorption]
The surface of the obtained sample (surface-modified elastic body) was brought into contact with a 1 mg/ml bovine serum albumin (BSA) solution and allowed to stand at 37° C. for 3 hours. The sample surface was lightly washed with phosphate buffered saline to prepare a protein adsorption sample. Put the entire amount of the protein-adsorbed sample into a 50 ml centrifuge tube, and remove the protein adsorbed on the sample surface according to the method described in JIS T9010: 1999 "Test method for biological safety of rubber products", Section 3.6 Water-soluble protein. Extracted. 0.5 ml of a 0.1 mol/l sodium hydroxide aqueous solution was accurately added to the obtained protein to dissolve it, and a sample solution was prepared. In addition, an operation blank was obtained by performing the same operation without adding the sample.
0.2 ml of sample solution and standard solution (BSA solution (5 to 100 μg/ml)) were accurately taken, and the amount of protein was quantified by the Lowry method. A calibration curve was prepared from the BSA concentration (μg/ml) and the absorbance of the standard solution, and the protein concentration (μg/ml) per 1 ml of the sample solution was calculated using this. converted to the value of

As can be seen from Tables 1 and 2, the surfaces of the surface-modified elastic bodies of Examples had a significantly reduced frictional resistance and good slidability. In addition, good liquid wetting resistance and protein adsorption suppression were also obtained. In particular, when a silane compound containing 50% by mass or more of a fluoroalkyl group-containing silane compound was reacted (added) to the surface, extremely excellent liquid leakage resistance was obtained. With regard to the protein adsorption inhibitory property, when the protein adsorption amount exceeds 1.0 μg/cm ² , it indicates that the protein has progressed to a multi-layered state, and is considered to be in a state where adsorption is dominant. is 0.7 μg/cm ² or less, which means that the protein is in a monolayer state, adsorption and desorption occur simultaneously, and adsorption is not dominant (adsorption does not increase any more). Do you get it. In addition, in Comparative Example 2 using only the perfluoroether group-containing silane compound, the amount of protein adsorption was as high as 1.41 μg/cm ² , suggesting that adsorption was dominant.

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 as well as the sufficient liquid leakage resistance, so that the procedure with the syringe can be performed easily and accurately. In addition, protein adsorption can be sufficiently suppressed.

Furthermore, by forming modified polymer chains on surfaces such as grooves, sidewalls, diaphragms, running surfaces of skis and snowboards, swimming suits, road signs, signboards, etc. formed in the tread of tires used in passenger cars, etc. , the aforementioned effect can also be expected.

1 base gasket (before immobilization of modified polymer chains)
2 Syringe gasket (after immobilization of modified polymer chains)
12 top surface portion 13 bottom surface portion 14 sliding portion (body portion)
14a First protrusion 14b Intermediate protrusion 14c Bottom side protrusion 21 Modified polymer chain

Claims (18)

A surface modification method in which vulcanized rubber is the object to be modified,
Step 1 of forming a polymerization initiation point A on the surface of the object to be modified;
Step 2 of radically polymerizing a monomer starting from the polymerization initiation point A to grow a polymer chain;
a step 3 of adding a silane compound to the surface of the polymer chain and further reacting at least the fluoroalkyl group-containing silane compound and the perfluoroether group-containing silane compound to form a modified polymer chain;
The mixing ratio of the fluoroalkyl group-containing silane compound and the perfluoroether group-containing silane compound is 50:50 to 100:0 (excluding 100:0),
The surface modification method, wherein the fluoroalkyl group is a group represented by the following formula.
F ₃ C—(CF ₂ ) _n —(CH ₂ ) _m —
(In the formula, n is an integer of 1 to 5 and m is an integer of 1 to 8.) A surface modification method in which vulcanized rubber is the object to be modified,
Step I of radically polymerizing a monomer on the surface of the object to be modified in the presence of a photopolymerization initiator A to grow a polymer chain;
a step II of adding a silane compound to the surface of the polymer chain and further reacting at least the silane compound containing a fluoroalkyl group and the silane compound containing a perfluoroether group to form a modified polymer chain;
The mixing ratio of the fluoroalkyl group-containing silane compound and the perfluoroether group-containing silane compound is 50:50 to 100:0 (excluding 100:0),
The surface modification method, wherein the fluoroalkyl group is a group represented by the following formula.
F ₃ C—(CF ₂ ) _n —(CH ₂ ) _m —
(In the formula, n is an integer of 1 to 5 and m is an integer of 1 to 8.) 3. The surface modification method according to claim 1, wherein the vulcanized rubber has a Shore A hardness of 50 to 70 . 3. The surface modification method according to claim 1, wherein the vulcanized rubber has a Shore A hardness of 53 to 65 . The monomers include acrylic acid, acrylic acid esters, alkali metal acrylic acid salts, amine acrylic acid salts, acrylamide, dimethylacrylamide, diethylacrylamide, isopropylacrylamide, hydroxyethylacrylamide, acryloylmorpholine, methoxymethyl acrylate, hydroxyethyl acrylate, methacrylic acid. , methacrylic acid esters, alkali metal methacrylic acid salts, amine methacrylic acid salts, methacrylamide, dimethyl methacrylamide, diethyl methacrylamide, isopropyl methacrylamide, hydroxyethyl methacrylamide, methacryloylmorpholine, methoxymethyl methacrylate, hydroxyethyl methacrylate, and acrylonitrile The surface modification method according to any one of claims 1 to 4 , wherein at least one selected from the group consisting of: The surface modification method according to any one of claims 1 to 5 , wherein the fluoroalkyl group-containing silane compound is a compound represented by the following formula (1).
F ₃ C—(CF ₂ ) _n —(CH ₂ ) _m —Si(OR ¹ ) ₃ (1)
(In the formula, n is 1 to 5 and m is 1 to 8. R ¹ represents an alkyl group, which may be the same group or different groups.) The surface modification method according to any one of claims 1 to 6 , wherein the perfluoroether group-containing silane compound is a compound represented by the following formula (2) or (3).

(In formula (2), Rf ¹ represents a perfluoroalkyl group. Z represents a fluorine or trifluoromethyl group. a, b, c, d, and e are the same or different, and are 0 or 1 or more. represents an integer, a + b + c + d + e is 1 or more, and the order of existence of each repeating unit enclosed by a, b, c, d, and e is not limited in the formula Y is hydrogen or has 1 to 4 carbon atoms represents an alkyl group of X ¹ represents hydrogen, bromine or iodine, R ¹ represents a hydroxyl group or a hydrolyzable substituent, R ² represents hydrogen or a monovalent hydrocarbon group, l represents , 0, 1, or 2. m represents 1, 2, or 3. n represents an integer of 1 or more, and two asterisks (*) indicate that the sites are directly bonded to each other. .)

(In the formula (3), Rf ² is an unbranched linear perfluoropolyalkylene ether containing a unit represented by —(C _k F _2k )O— (k is an integer of 1 to 6). represents a divalent group having a structure, R ³ is the same or different and represents a monovalent hydrocarbon group having 1 to 8 carbon atoms, and X ² is the same or different and represents a hydrolyzable group or a halogen atom s is the same or different and represents an integer of 0 to 2. t is the same or different and represents an integer of 1 to 5. h and i are the same or different and represent 1, 2 or 3.) The surface modification method according to any one of claims 1 to 7 , wherein the length of the modified polymer chain formed is 200 to 7000 nm. A surface-modified elastic body in which at least a part of a three-dimensional solid surface has been modified by the surface modification method according to any one of claims 1 to 8 . A syringe gasket having at least a portion of its surface modified by the surface modification method according to any one of claims 1 to 8 . 11. The syringe gasket according to claim 10 , wherein the polymer chains are immobilized on at least part of the surface of the base gasket, and the sliding surface has a plurality of annular projections,
A gasket for a syringe, wherein, of the annular protrusions, a first protrusion closest to the top surface has a surface roughness Ra of 1.0 or less. 12. The syringe gasket according to claim 11 , wherein said surface roughness Ra is 0.8 or less. 12. The syringe gasket according to claim 11 , wherein said surface roughness Ra is 0.6 or less. The syringe gasket according to any one of claims 11 to 13 , wherein the base gasket has a surface roughness Ra of 1.0 or less. The syringe gasket according to any one of claims 11 to 13, wherein the base gasket has a surface roughness Ra of 0.8 or less. The syringe gasket according to any one of claims 11 to 13, wherein the base gasket has a surface roughness Ra of 0.6 or less. 11. The syringe gasket according to claim 10 , wherein the polymer chains are immobilized on at least part of the surface of the base gasket, and the sliding surface has a plurality of annular projections,
A gasket for a syringe, wherein the surface roughness Rz of the first protrusion closest to the top surface of the annular protrusion is 25.0 or less. 11. The syringe gasket according to claim 10 , wherein the polymer chains are immobilized on at least part of the surface of the base gasket, and the sliding surface has a plurality of annular projections,
A gasket for a syringe, wherein, of the annular protrusions, a first protrusion closest to the top surface has a surface roughness Rv of 21.0 or less.

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