JP6109607B2 - Surface modification method for three-dimensional object and gasket for syringe - Google Patents

Description

The present invention relates to a surface modification method for a plurality of three-dimensional objects, and a gasket for a syringe whose surface is modified by the method.

Various products made of a three-dimensional object such as a gasket that is integrated with a plunger of a syringe and seals the plunger and the syringe have been proposed. As such a three-dimensional shaped product, various products with surface modification are provided and used for various applications. Conventionally, when surface modification is performed, each three-dimensional shaped product is individually modified. The technique is widely used.

For this reason, there are problems such as poor productivity, unsuitable for mass production and difficult to put into practical use, and a manufacturing method in which individual surface modification treatment is performed is expensive and economical.

The present invention solves the above-mentioned problems, improves the surface of a plurality of three-dimensional objects at the same time, and provides good slidability, durability against repeated sliding and sealing performance, etc. It is an object to provide a surface modification method and a gasket for a syringe obtained by the surface modification method.

The present invention comprises a step 1 of immersing a plurality of three-dimensionally-shaped products in a photopolymerizable monomer-containing liquid, and the photopolymerizable monomer is polymerized by light irradiation while stirring the photopolymerizable monomer-containing liquid. And a step 2 of growing a polymer chain on the surface of the three-dimensional object.

The photopolymerizable monomer is acrylic acid, acrylic acid ester, acrylic acid alkali metal salt, acrylic acid amine salt, methacrylic acid, methacrylic acid ester, methacrylic acid alkali metal salt, methacrylic acid amine salt, acrylonitrile, acrylamide, dimethylacrylamide, It is preferably at least one selected from the group consisting of diethyl acrylamide, isopropyl acrylamide, hydroxy acrylamide, acryloyl morpholine, methacrylamide, dimethyl methacrylamide, diethyl methacrylamide, isopropyl methacrylamide, hydroxy methacrylamide, and methacryloyl morpholine. .

The photopolymerizable monomer-containing liquid preferably contains a polymerization initiator. Here, the polymerization initiator is preferably a benzophenone compound and / or a thioxanthone compound.

The photopolymerizable monomer-containing liquid preferably contains 20 to 500 ppm of a polymerization inhibitor.
The rotation speed of the stirring is preferably 50 to 1000 rpm.
The wavelength of light in the light irradiation is preferably 300 to 400 nm.

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 the light irradiation or before the light irradiation, and the polymerization is performed by replacing the inert gas atmosphere. Further, it is preferable to perform the polymerization by evacuating the reaction vessel during the light irradiation or before the light irradiation to degas oxygen.

Prior to Step 1, it is preferable that a polymerization initiator is adsorbed in advance on the surface of the three-dimensionally shaped product. Moreover, before the said process 1, it is preferable to make a polymerization initiator adsorb | suck to the surface of the said three-dimensional shaped object previously, and to fix this polymerization initiator to the surface by light irradiation.

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

According to the present invention, the step 1 of immersing a plurality of three-dimensionally shaped products in the photopolymerizable monomer-containing liquid, and while stirring the photopolymerizable monomer-containing liquid, the photopolymerizable monomer is polymerized by light irradiation, And a step 2 of growing the polymer chain on the surface of the plurality of three-dimensional objects. The method for modifying the surface of the three-dimensional object includes a photopolymerizable polymer chain simultaneously on each surface of the plurality of three-dimensional objects. In addition, it can be formed while suppressing variation, and can impart excellent slidability, durability against repeated sliding, and sealing properties to individual three-dimensional shapes. Therefore, by applying the surface modification method, it is possible to produce a surface-modified elastic body such as a plurality of gaskets for syringes excellent in these performances with high productivity.

An example of the schematic diagram regarding the radical polymerization of the process 2. FIG.

The surface modification method for a three-dimensional object of the present invention includes a step 1 of immersing a plurality of three-dimensional objects in a photopolymerizable monomer-containing liquid, and photopolymerization by light irradiation while stirring the photopolymerizable monomer-containing liquid. And a step 2 of polymerizing a polymerizable monomer to grow a polymer chain on the surface of the plurality of three-dimensional shapes.

In step 1, a plurality of three-dimensionally shaped products are immersed in a photopolymerizable monomer-containing liquid.
Examples of the three-dimensional shape include vulcanized rubber and thermoplastic elastomer, and among them, those having a carbon atom adjacent to the double bond (allylic carbon atom) are preferably used.

Examples of rubbers in vulcanized rubber 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. It is done. In the case of butyl rubber and halogenated butyl rubber, a crosslinked rubber made of triazine is preferable because the extract from 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.

In addition, it is preferable to perform the process of forming a polymerization start point on each surface of the plurality of three-dimensional products before immersing the plurality of three-dimensional products in the photopolymerizable monomer-containing liquid in Step 1.

The polymerization starting point is formed, for example, by adsorbing a polymerization initiator on each surface of a plurality of three-dimensionally shaped products. Examples of the polymerization initiator include carbonyl compounds, organic sulfur compounds such as tetraethylthiuram disulfide, persulfides, redox compounds, azo compounds, diazo compounds, halogen compounds, and photoreductive dyes. Compounds are preferred.

As the carbonyl compound as a polymerization initiator, benzophenone and its derivatives are preferable. For example, a benzophenone-based compound represented by the following formula can be suitably used.

(Wherein 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 (fluorine, chlorine, bromine, iodine), a hydroxyl group, a primary to tertiary amino group, It represents 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 may be linked together to form a ring structure together with the carbon atoms to which they are bonded. )

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.

（式中、Ｒ^１１〜Ｒ^１４及びＲ^１１′〜Ｒ^１４′は、同一若しくは異なって、水素原子、ハロゲン原子、アルキル基、環状アルキル基、アリール基、アルケニル基、アルコキシ基、又はアリールオキシ基を表す。） As the polymerization initiator, a thioxanthone compound can also be suitably used because it has a high polymerization rate and easily adsorbs and / or reacts with rubber or the like. For example, a compound represented by the following formula can be preferably used.

(In the formula, R ^{11 to} R ¹⁴ and R ¹¹ ′ to R ¹⁴ ′ are the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group, a cyclic alkyl group, an aryl group, an alkenyl group, an alkoxy group, or an aryloxy group. Represents.)

Examples of the thioxanthone compound represented by the above formula include thioxanthone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,3-dimethylthioxanthone, 2,4-dimethylthioxanthone, 2,3-diethylthioxanthone, 2,4-diethylthioxanthone. 2,4-dichlorothioxanthone, 2-methoxythioxanthone, 1-chloro-4-propoxythioxanthone, 2-cyclohexylthioxanthone, 4-cyclohexylthioxanthone, 2-vinylthioxanthone, 2,4-divinylthioxanthone, 2,4-diphenylthioxanthone 2-butenyl-4-phenylthioxanthone, 2-methoxythioxanthone, 2-p-octyloxyphenyl-4-ethylthioxanthone, and the like. Among ^them, one or two of R 11 ^{to R 14} and ^R 11 ^{'~R 14',} is preferably one in particular two are substituted by an alkyl group, 2,4-Diethylthioxanthone (2,4- diethyl Thioxanthone) is more preferred.

As a method for adsorbing a polymerization initiator such as a benzophenone compound or a thioxanthone compound on the surface of a three-dimensional object, a known method may be used. For example, for benzophenone compounds and thioxanthone compounds, the surface part of the three-dimensional product to be modified is adsorbed on the surface by treatment with a solution obtained by dissolving benzophenone compounds and thioxanthone compounds in an organic solvent. The polymerization starting point is formed by evaporating the organic solvent by drying as necessary. The surface treatment method is not particularly limited as long as the benzophenone compound solution and the thioxanthone compound solution can be brought into contact with the surface of the three-dimensional object. For example, the benzophenone compound solution and the thioxanthone compound solution Application, spraying, and immersion in the solution are suitable. Further, when surface modification is required only on a part of the surface, the polymerization initiator may be adsorbed only on the part of the surface that is necessary. 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 three-dimensional shape, and it can be quickly dried and evaporated.

Further, it is preferable that the modification target site is subjected to a surface treatment with a benzophenone-based compound solution or a thioxanthone-based compound solution to adsorb the polymerization initiator, and then further irradiated with light to be chemically bonded to the surface of the three-dimensionally shaped product. For example, the benzophenone compound or thioxanthone compound solution can be immobilized on the surface by irradiation with ultraviolet rays having a wavelength of 300 to 450 nm (preferably 300 to 400 nm, more preferably 350 to 400 nm). In the formation and immobilization of the polymerization initiator described above, hydrogen on the rubber surface is extracted, and a covalent bond is formed between the C═O carbon of benzophenone and the carbon on the rubber surface. Bonding to oxygen of O forms 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.

Among them, each surface of a plurality of three-dimensionally shaped products is treated with a polymerization initiator so that the polymerization initiator is adsorbed on each surface, and then the treated surface is irradiated with 300 to 400 nm LED light. It is preferable to form a polymerization initiator, and in particular, after the surface of the three-dimensional product is subjected to a surface treatment with a benzophenone compound solution, a thioxanthone compound solution, etc. to adsorb the polymerization initiator, the surface after the treatment is further treated It is preferable to chemically bond the adsorbed polymerization initiator to the surface by irradiating LED light of 300 to 400 nm. Here, the wavelength of the LED light is preferably 355 to 380 nm.

Examples of the photopolymerizable monomer used in Step 1 include (meth) acrylic acid, (meth) acrylic acid ester, (meth) acrylic acid alkali metal salt, and (meth) acrylic acid amine salt. A monomer having a C—N bond is also exemplified. Monomers having a C—N bond in the molecule include (meth) acrylamide; N-alkyl-substituted (meth) acrylamide derivatives (N-ethyl (meth) acrylamide, Nn-propyl (meth) acrylamide, N-isopropyl ( (Meth) acrylamide, N-cyclopropyl (meth) acrylamide, N-ethoxyethyl (meth) acrylamide, etc.); N, N-dialkyl-substituted (meth) acrylamide derivatives (N, N-dimethyl (meth) acrylamide, N, N-) Ethyl methyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, etc.); hydroxy (meth) acrylamide; hydroxy (meth) acrylamide derivatives (N-hydroxyethyl (meth) acrylamide etc.); having a cyclic group (meth) Acrylamide derivatives ((meta Acryloyl morpholine, etc.) and the like. Among them, (meth) acrylic acid, (meth) acrylic acid ester, (meth) acrylic acid alkali metal salt, (meth) acrylic acid amine salt, acrylonitrile, (meth) acrylamide, dimethyl (meth) acrylamide, diethyl (meth) Acrylamide, isopropyl (meth) acrylamide, hydroxy (meth) acrylamide, and (meth) acryloylmorpholine are preferable, and (meth) acrylamide, particularly acrylamide is preferable.

As described above, the polymerization initiator may be adsorbed and immobilized on the surface of the three-dimensional object in advance, but the polymerization initiator is included as a liquid containing the photopolymerizable monomer in Step 1 (photopolymerizable monomer-containing liquid). Things may be used. In this case, the polymerization initiator is irradiated with light to generate radicals from the initiator, and then the radicals draw hydrogen from the surface of the three-dimensional object to generate radicals on the surface of the three-dimensional object, and are generated on the surface. The graft polymerization of the monomer starts from the radical. Therefore, as the polymerization initiator, a hydrogen abstraction type polymerization initiator such as the benzophenone or thioxanthone compound is suitable.

Moreover, it is preferable to use what contains a polymerization inhibitor as a photopolymerizable monomer containing liquid, and to superpose | polymerize in presence of this polymerization inhibitor. The polymerization inhibitor is preferably 4-methylphenol. Here, the content of the polymerization inhibitor in the photopolymerizable monomer-containing liquid is preferably 20 to 500 ppm.

In step 1, a plurality of three-dimensionally shaped products are immersed in the photopolymerizable monomer-containing liquid, but the dipping method is not particularly limited, and a plurality of three-dimensional objects that are the modification target are included in the photopolymerizable monomer-containing liquid. Any method that can simultaneously immerse the shape can be employed.

After the immersion in Step 1, Step 2 is performed in which the photopolymerizable monomer is polymerized by light irradiation while the photopolymerizable monomer-containing liquid is stirred, and polymer chains are grown on the surfaces of a plurality of three-dimensional shapes. The radical polymerization of the photopolymerizable monomer in step 2 is performed by, for example, immersing a plurality of three-dimensionally shaped products adsorbed or covalently bonded with a benzophenone compound, a thioxanthone compound, etc. in a photopolymerizable monomer-containing liquid, , Each radical polymerization (photo radical polymerization) proceeds, and a polymer chain grows on the surface of each three-dimensional shape.

In addition, the stirring method of a photopolymerizable monomer containing liquid is not specifically limited, A conventionally well-known method can be used. In addition, the number of rotations during stirring may be set as appropriate as long as the polymer chain is formed on the surface of each three-dimensional object, but each of the plurality of three-dimensional objects revolves and rotates, and the surface is substantially uniform. 50-1000 rpm is suitable from the point that light can be irradiated.

In the present invention, radical polymerization of the monomer proceeds by irradiating with light after immersion in a photopolymerizable monomer-containing liquid (photopolymerizable monomer (liquid), solution thereof, etc.). A UV irradiation light source such as a high-pressure mercury lamp, a metal halide lamp, or an LED lamp can be suitably used. The amount of irradiation light may be appropriately set in consideration of the polymerization time and the uniformity of reaction progress. 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, The inside of the reaction vessel is evacuated and oxygen is degassed as appropriate. Furthermore, in order to prevent reaction inhibition such as oxygen, a UV irradiation light source is installed at a position where an air layer (oxygen content of 15% or more) does not enter between a reaction vessel such as glass or plastic and a reaction solution or a three-dimensional object. Devise, etc. are also performed suitably.

When irradiating with ultraviolet rays, the wavelength is preferably 300 to 450 nm, more preferably 300 to 400 nm. Thereby, a polymer chain can be favorably formed on each surface of a plurality of three-dimensional objects without variation. In addition, radicals are not initially generated from the surface of the monomer or three-dimensional object, and radicals can be generated only from the polymerization initiator. Ultraviolet light of less than 300 nm also has the negative effect of forming a free polymer by polymerizing monomers alone, not from the surface. As the light source, a high-pressure mercury lamp, an LED having a central wavelength of 365 nm, an LED having a central wavelength of 375 nm, or the like can be used. Especially, it is preferable to irradiate 300-400 nm LED light, and it is more preferable to irradiate 355-380 nm LED light. In particular, an LED having a center wavelength of 365 nm close to the excitation wavelength of benzophenone of 366 nm is preferable from the viewpoint of efficiency. In addition, in the case of ultraviolet rays (such as a high-pressure mercury lamp) that emit light of various wavelengths, there is a method of irradiating after cutting a wavelength of less than 300 nm with a filter.

In Step 2, by forming a polymer chain on the surface of each three-dimensionally shaped product, excellent slidability and durability can be obtained, and good sealing properties can be maintained. The degree of polymerization of the formed polymer chain is preferably 20 to 200000, more preferably 350 to 50000. If it is less than 20, the polymer chain is too short and is buried in the irregularities on the surface of the three-dimensional shape, and there is a tendency that the slidability is not exhibited. If it exceeds 200,000, the amount of monomer used increases, which tends to be economically disadvantageous.

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 Step 2, two or more kinds of photopolymerizable monomers may be radically polymerized starting from the polymerization starting point, and plural types of polymer chains may be grown on the surface of each three-dimensionally shaped product. The surface modification method may be a method of crosslinking between polymer chains. In this case, ionic cross-linking or cross-linking by a hydrophilic group having an oxygen atom may be formed between the polymer chains. Furthermore, a cross-linked structure may be introduced between the polymer chains during the polymerization by adding a small amount of a compound having two or more vinyl groups in one molecule and polymerizing. As a compound having two or more vinyl groups in one molecule, N, N′-methylenebisacrylamide and the like are preferable.

FIG. 1 shows an example of a schematic diagram relating to radical polymerization in step 2. In this step, the photopolymerizable monomer-containing liquid in which a plurality of three-dimensional objects (gaskets) are immersed is stirred with a stirrer having a predetermined rotation number so that the surface of each three-dimensional object is uniformly irradiated with light. On the other hand, by irradiating with ultraviolet rays (365 nm UV light), radical polymerization of the photopolymerizable monomer proceeds on the surface of each three-dimensionally shaped product, and a polymer chain grows on each surface. Thereby, a plurality of surface-modified elastic bodies such as a gasket for a syringe in which polymer chains are formed on each surface of a plurality of three-dimensionally shaped products without variation can be manufactured simultaneously.

By applying the surface modification method to a plurality of three-dimensional objects, a plurality of surface modified elastic bodies can be manufactured simultaneously. For example, a surface-modified elastic body excellent in slidability in the presence of water or in a dry state is obtained, which is excellent in that it has low friction and low 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 a substantially vertical direction from the surface of the three-dimensionally shaped product in that the entropy is small and the molecular motion of the graft chain is lowered, so that the slidability is secured. Furthermore, as the brush density, a quasi-density and a density brush that are 0.01 chains / nm ² or more are preferable.

In addition, by applying the surface modification method to a plurality of three-dimensional objects, a plurality of gaskets for a syringe having at least a part of the modified surface can be manufactured simultaneously. The modification is preferably performed at least on the sliding portion of the gasket surface, and may be performed on the entire surface.

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

Example 1
10 gaskets (gaskets containing chlorobutyl rubber containing isoprene units (unsaturation: 1 to 2%) crosslinked with triazine, vulcanized at 180 ° C for 10 minutes) were immersed in 1 wt% acetone solution of benzophenone for 5 minutes, then taken out and dried did. In a 300 ml separable flask, 150 ml of 1M acrylamide aqueous solution and 10 gaskets dried above were put in order, and the gasket was immersed in the acrylamide aqueous solution. Then, the inside was purged with argon for 120 minutes to remove oxygen. While stirring the flask at a rotation speed of 500 rpm, irradiation with LED-UV light (having a wavelength of 365 nm) with an irradiation intensity of 15 mW / cm ² was performed for 150 minutes, and acrylamide was grafted onto each gasket surface to grow a polymer chain. It was. Thereafter, the gasket was taken out, washed with water and dried to obtain a syringe gasket (polymer brush).

(Example 2)
To a 300 ml separable flask, 150 ml of 1M acrylamide aqueous solution and 1 mg of benzophenone were sequentially added, 10 gaskets were further added, and the gasket was immersed in the acrylamide aqueous solution. Then, the inside was purged with argon for 120 minutes to remove oxygen. While stirring the inside of the flask at a rotation speed of 500 rpm, LED-UV light having an irradiation intensity of 15 mW / cm ² was irradiated for 150 minutes, and acrylamide was graft-polymerized on each gasket surface to grow a polymer chain. Thereafter, the gasket was taken out, washed with water and dried to obtain a syringe gasket.

(Example 3)
A syringe gasket was obtained in the same manner as in Example 1 except that 150 ml of 1M acrylamide aqueous solution was changed to 150 ml of 1M acrylamide aqueous solution containing 50 pppm of a polymerization inhibitor.

Example 4
A gasket for a syringe was obtained in the same manner as in Example 1 except that 150 ml of 1M acrylamide aqueous solution was changed to 150 ml of 1M acrylamide / acrylic acid (1: 1) aqueous solution.

(Example 5)
A gasket for a syringe was obtained in the same manner as in Example 1 except that the inside was purged with argon for 120 minutes and oxygen was removed instead of evacuating with a pump (120 minutes) to remove the oxygen inside. .

(Example 6)
A syringe gasket was obtained in the same manner as in Example 1 except that the rotation speed was changed from 500 rpm to 20 rpm.

(Example 7)
A syringe gasket was obtained in the same manner as in Example 1 except that the rotation speed was changed from 500 rpm to 1200 rpm.

(Comparative Example 1)
Ten gaskets (a chlorobutyl rubber containing an isoprene unit (unsaturation: 1 to 2%) cross-linked with triazine, vulcanized at 180 ° C. for 10 minutes) were used.

(Comparative Example 2)
One gasket was immersed in a 1 wt% benzophenone acetone solution for 5 minutes, then taken out and dried. Into a 20 ml glass container, 10 ml of 1M acrylamide aqueous solution and the gasket dried above were put in order, and the gasket was immersed in the acrylamide aqueous solution. Then, the inside was purged with argon for 60 minutes to remove oxygen. While rotating a 20 ml glass container at a rotation speed of 10 rpm, LED-UV light with an irradiation intensity of ² mW / cm ² was irradiated for 75 minutes, and acrylamide was graft-polymerized on the gasket surface to grow a polymer chain. Thereafter, the gasket was taken out, washed with water and dried. The above operation was repeated 10 times to obtain a gasket for a syringe grafted on 10 surfaces. The total polymerization time took 75 minutes × 10 = 750 minutes.

The gaskets for syringes 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.

(Friction resistance)
In order to measure the frictional resistance of the surface of the gasket for the syringe, the gaskets prepared in the examples and comparative examples were set in the COP resin syringe of the syringe and pushed in using a tensile tester, and the frictional resistance at that time Was measured (pushing speed: 100 mm / min). The friction resistance force of Comparative Example 1 was set to 100, and the following formula was used, and each Example and Comparative Example were shown as a frictional resistance index. A smaller index indicates a lower frictional resistance. The frictional resistance of each of the 10 gaskets produced was measured, and the average value was calculated. Furthermore, the variation in the frictional resistance of each gasket was evaluated by the standard deviation of 10 frictional resistances.
(Friction resistance index) = Friction resistance of each Example / Friction resistance of Comparative Example 1 × 100

From Table 1, each surface of the many gaskets for syringes produced in the examples has a significantly reduced average frictional resistance, good slidability, and only the surface is modified. Was equivalent to Comparative Example 1. In addition, it has been clarified that a large number of surface-modified gaskets having a uniform performance can be manufactured with high productivity with little variation in frictional resistance.

Claims (11)

Step 1 of immersing a plurality of three-dimensionally shaped products in a photopolymerizable monomer-containing liquid, and stirring the photopolymerizable monomer-containing liquid while polymerizing the photopolymerizable monomer by light irradiation, the plurality of three-dimensionally shaped products And a step 2 of growing a polymer chain on the surface of the syringe. The photopolymerizable monomer is acrylic acid, acrylic acid ester, acrylic acid alkali metal salt, acrylic acid amine salt, methacrylic acid, methacrylic acid ester, methacrylic acid alkali metal salt, methacrylic acid amine salt, acrylonitrile, acrylamide, dimethylacrylamide, 2. At least one selected from the group consisting of diethyl acrylamide, isopropyl acrylamide, hydroxy acrylamide, acryloyl morpholine, methacrylamide, dimethyl methacrylamide, diethyl methacrylamide, isopropyl methacrylamide, hydroxy methacrylamide, and methacryloyl morpholine. The manufacturing method of the gasket for syringes of description. The manufacturing method of the gasket for syringes of Claim 1 or 2 with which the said photopolymerizable monomer containing liquid contains a polymerization initiator. The method for producing a gasket for a syringe according to claim 3, wherein the polymerization initiator is a benzophenone compound and / or a thioxanthone compound. The manufacturing method of the gasket for syringes in any one of Claims 1-4 with which the said photopolymerizable monomer containing liquid contains 20-500 ppm of polymerization inhibitors. The method for producing a gasket for a syringe according to any one of claims 1 to 5, wherein the number of rotations of the stirring is 50 to 1000 rpm. The method for producing a syringe gasket according to claim 1, wherein a wavelength of light in the light irradiation is 300 to 400 nm. The method for producing a gasket for a syringe according to any one of claims 1 to 7, wherein an inert gas is introduced into a reaction vessel and a reaction solution at the time of the light irradiation or before the light irradiation, and the polymerization is performed by replacing with an inert gas atmosphere. The manufacturing method of the gasket for syringes in any one of Claims 1-7 which evacuate a reaction container at the time of the said light irradiation or before light irradiation, and deaerate and superpose | polymerize. The manufacturing method of the gasket for syringes in any one of Claims 1-9 which make a polymerization initiator adsorb | suck beforehand on the surface of the said three-dimensionally shaped object before the said process 1. The manufacturing of the gasket for a syringe according to any one of claims 1 to 10, wherein a polymerization initiator is adsorbed in advance on the surface of the three-dimensionally shaped product and the polymerization initiator is fixed to the surface by light irradiation before the step 1. Method.

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