Gasket for syringe

Abstract

To provide a gasket for a syringe where a friction coefficient and adhesiveness on a surface are reduced, and a production method of the same.SOLUTION: A gasket 40 for a syringe is formed of a rubber composition containing (a) a base material polymer containing halogenated butyl rubber, and (b) resin particles. At least a part of a surface of the gasket for syringe is configured so that, in an image analysis result obtained when surface roughness is measured by a laser microscope, a volume Vmp (mL / m2) of a protrusion crest part when a load area ratio for separating a core part and the protrusion crest part is 40%, and a content V(%) of (a) the base material polymer in the rubber composition, satisfy P=(Vmp / V)≥0.25.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a gasket for a syringe, and more particularly to a technique for improving the slidability of a gasket for a syringe.

Background Art

[0002] Conventionally, prefilled syringes prefilled with a drug have been used for reasons such as prevention of drug administration errors, prevention of nosocomial infections, disposability, and efficiency of hospital operations. Regardless of the prefilled syringe, a syringe generally includes a barrel, a gasket that can slide airtightly and liquidtightly inside the barrel, and a plunger that moves this gasket. The gasket used in a syringe is required to have not only sealing performance (airtightness and liquidtightness) but also high slidability (for example, low initial sliding resistance and low sliding resistance over time) in order to smoothly administer the drug.

[0003] Patent Document 1 discloses a prefilled syringe comprising an outer cylinder having a nozzle portion at the tip and an opening at the base end, a gasket that slides inside the outer cylinder, a pusher connected to the gasket through the opening, and a drug solution sealed and stored inside the outer cylinder by the gasket. The periphery of the opening has a flange extending outward from the outer cylinder, and a movable stopper is provided on the flange. A locking portion is provided on a portion of the pusher extending outside the outer cylinder from the opening. By moving the gasket in the tip direction through the pusher and locking the locking portion to the stopper at a position where bubbles present in the drug solution and the excess amount of the drug solution are discharged from the nozzle, the gasket stops.

[0004] Patent Document 2 discloses a gasket formed to be in liquid-tight sliding contact within the outer cylinder of a syringe. The gasket includes a gasket body made of an elastic body and a coating layer provided at least on a portion in contact with the syringe. The coating layer is composed of a composition containing a silicone resin having a siloxane bond derived from a silanol group and composed of a condensate of a reactive silicone having terminal silanol groups, and does not contain solid fine particles. A syringe gasket is disclosed which is characterized in that it is composed of such a composition and does not contain solid fine particles.

[0005] Patent Document 3 discloses a rubber product suitably used as a piston rubber for a syringe. The rubber product is constituted by a rubber composition containing 10 to 80 parts by weight of fine fluororesin powder having an average particle size of 1 to 5 μm with respect to 100 parts by weight of butyl rubber as a component, and a highly permeable liquid-sealing rubber product having a fluororesin film formed by a casting method laminated on the surface is disclosed.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0007] In order to improve slidability, silicone oil is applied to the surface of the syringe gasket. However, when a syringe gasket coated with silicone oil comes into contact with a biopharmaceutical, there is a risk of protein aggregation due to silicone particles. Therefore, syringe gaskets coated with silicone oil cannot be used for medical supplies that use biopharmaceuticals. In particular, for syringe gaskets of prefilled syringes, the need for silicone oil free (SOF) is increasing.

[0008] In addition, in order to prevent the components constituting the syringe gasket from mixing into the chemical solution in the syringe barrel and contaminating or altering the chemical solution, the syringe gasket is laminated with a fluororesin film. A syringe gasket laminated with a fluororesin film such as a polytetrafluoroethylene (PTFE) film has an elastic modulus of the PTFE film 100 times higher than that of rubber, and the sealing performance tends to decrease.

[0009] Under such circumstances, as a countermeasure against silicone oil free (SOF) regulations, a method of reducing the friction coefficient and adhesiveness of the syringe gasket without using silicone oil is required.

[0010] The present invention has been made in view of the above circumstances, and an object thereof is to provide a novel syringe gasket with a reduced surface friction coefficient and adhesiveness and a method for manufacturing the same.

Means for Solving the Problems

[0011] The syringe gasket of the present invention is a syringe gasket formed from a rubber composition containing (a) a base polymer containing halogenated butyl rubber and (b) resin particles, wherein at least a part of the surface of the syringe gasket has a load area ratio for separating the core part and the protruding mountain part of 40% with respect to the image analysis result obtained when measuring the surface roughness with a laser microscope. The volume Vmp (mL / m of the protruding mountain part 2) and the content ratio V (mass %) of the (a) base polymer in the rubber composition satisfy P = (Vmp / V) ≥ 0.25.

[0012] The volume Vmp of the protruding peak portion indicates the volume of the convex portion protruding on the surface of the gasket. Further, V is the content ratio (mass %) of the (a) base polymer in the rubber composition. (a) The base polymer is the main component constituting the gasket body. Therefore, P = (Vmp / V) indicates the volume of the protruding convex portion on the surface per unit base polymer. The larger the P, the larger the volume of the protruding convex portion per unit base polymer, so the surface of the syringe gasket becomes rough and the contact area between the syringe gasket and the syringe barrel decreases. As a result, the friction coefficient becomes small and the slidability is improved.

[0013] The manufacturing method of the syringe gasket of the present invention includes a step of molding a rubber composition containing (a) a base polymer containing halogenated butyl rubber and (b) resin particles into a syringe gasket, and a step of irradiating at least a part of the surface of the syringe gasket with ultraviolet rays.

[0014] According to the manufacturing method of the present invention, by irradiating the surface of the syringe gasket formed by molding a rubber composition containing (a) a base polymer containing halogenated butyl rubber and (b) resin particles with ultraviolet rays, low molecular components that cause adhesiveness on the surface of the syringe gasket are decomposed and evaporated, and low adhesiveness can be realized. Further, due to the evaporation of the low molecular components, the (b) resin particles are exposed on the surface of the syringe gasket and the surface becomes rough, so that the friction coefficient can be further reduced.

Effects of the Invention

[0015] According to the present invention, a syringe gasket with reduced surface friction coefficient and adhesiveness can be obtained.

Brief Description of the Drawings

[0016]

Figure 1

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Figure 3

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Figure 6

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Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0017] The syringe gasket of the present invention is a syringe gasket formed from a rubber composition containing (a) a base polymer containing halogenated butyl rubber and (b) resin particles, and at least a part of the surface of the syringe gasket is such that, for the image analysis result obtained when measuring the surface roughness with a laser microscope, the volume Vmp (mL / m 2 ) of the protruding peak portion with a load area ratio of 40% separating the core portion and the protruding peak portion, and the content ratio V (mass%) of the (a) base polymer in the rubber composition satisfy P = (Vmp / V) ≧ 0.25.

[0018] The gasket for a syringe of the present invention is such that, for the image analysis result obtained when measuring the surface roughness with a laser microscope on at least a part of the surface of the gasket, the volume Vmp (mL / m 2 ) of the protruding peak part with a load area ratio of 40% that separates the core part and the protruding peak part, and the content V (mass%) of the (a) base polymer in the rubber composition satisfy P=(Vmp / V)≧0.25.

[0019] The measurement of the surface roughness of the syringe gasket is performed using a laser microscope VK-X3000 manufactured by KEYENCE CORPORATION in the scan mode: laser confocal and with an objective lens magnification of 50 times.

[0020] For the image obtained by observing with a laser microscope, image processing is performed using the VK-X3000 multi-file analysis application (reference plane setting → planar correction (waviness removal: strength 5)). By this image processing, for example, a graph as shown in FIG. 1 is obtained. In FIG. 1, the horizontal axis represents the load area ratio, and the vertical axis represents the height. In FIG. 1, Vmp is the volume of the protruding peak part, Vmc is the volume of the core part, and Vvc is the volume of the space of the core part.

[0021] In the present invention, as a parameter of image analysis, the load area ratio that separates the core part and the protruding peak part is set to 40%.

[0022] In the present invention, the volume Vmp (mL / m 2 ) of the protruding peak part and the content V (mass%) of the rubber component in the rubber composition satisfy P=(Vmp / V)≧0.25. It is more preferable that the above-mentioned P is 0.28 or more, still more preferable that it is 0.30 or more, preferably 5.0 or less, more preferably 4.5 or less, and still more preferably 4.0 or less. This is because when the above-mentioned P is within the above-mentioned range, it is possible to achieve both sliding characteristics and airtight characteristics.

[0023] The gasket for a syringe of the present invention is preferably substantially cylindrical. The gasket for a syringe has a distal end side to be inserted into a syringe barrel and a proximal end side connected to a plunger. Note that the distal end side may be referred to as the distal side, and the proximal end side may be referred to as the proximal side. The gasket for a syringe has a top surface portion that contacts a chemical solution and a sliding surface portion that faces the inner surface of the syringe barrel when inserted into the syringe barrel.

[0024] The gasket for a syringe of the present invention preferably has one or more annular ribs on the sliding surface portion, and more preferably has a plurality of annular ribs. The annular ribs are in sliding contact with the inner surface of the syringe barrel. The plurality of annular ribs are arranged in the axial direction of the syringe gasket from the tip surface (top surface) to the rear end surface of the syringe gasket. The number of annular ribs is not particularly limited as long as it is 1 or more, but it is preferably 2 or more, more preferably 3 or more, preferably 6 or less, more preferably 5 or less, and even more preferably 4 or less.

[0025] It is preferable that at least a part of the top surface portion of the gasket for a syringe of the present invention is covered with an inert resin layer, and it is more preferable that the entire top surface portion is covered with an inert resin layer. By covering the top surface portion with an inert resin layer, it is possible to prevent the components constituting the gasket for a syringe from mixing into the drug in the syringe barrel and contaminating or altering the chemical solution.

[0026] The gasket for a syringe of the present invention has a top surface portion that contacts a chemical solution and a sliding surface portion that faces the inner surface of the syringe barrel when inserted into the syringe barrel. It is preferable that at least a part of the sliding surface portion satisfies P = (Vmp / V) ≥ 0.25, and it is more preferable that the entire sliding surface portion satisfies P = (Vmp / V) ≥ 0.25. By at least a part of the sliding surface portion satisfying P = (Vmp / V) ≥ 0.25, the syringe gasket exhibits good slidability.

[0027] In a preferred embodiment of the present invention, a part of the top surface portion of the syringe gasket is coated with an inert resin layer, and at least a part of the sliding surface portion satisfies P = (Vmp / V) ≧ 0.25. In a more preferred embodiment of the present invention, only the top surface portion of the syringe gasket is coated with an inert resin layer, and the entire sliding surface portion satisfies P = (Vmp / V) ≧ 0.25. In this embodiment, the inert resin layer exhibits good chemical resistance, and the sliding surface portion exhibits excellent slidability.

[0028] Examples of the inert resin layer include a layer made of a fluororesin or a layer made of a non-fluororesin.

[0029] Hereinafter, the material of the syringe gasket of the present invention will be described. The syringe gasket of the present invention is formed from a rubber composition containing (a) a base polymer containing a halogenated butyl rubber and (b) resin particles.

[0030] (a) The base polymer contains a halogenated butyl rubber as a rubber component. The halogenated butyl rubber has excellent gas barrier properties.

[0031] (a) Examples of the halogenated butyl rubber contained in the base polymer include chlorinated butyl rubber, brominated butyl rubber, and brominated products of copolymers of isobutylene and p-methylstyrene. These halogenated butyl rubbers may be used alone or in combination of two or more. As the halogenated butyl rubber, chlorinated butyl rubber or brominated butyl rubber is preferred. The chlorinated butyl rubber or brominated butyl rubber is, for example, obtained by adding or substituting chlorine or bromine to the isoprene structural portion in butyl rubber, specifically, a double bond and / or a carbon atom adjacent to the double bond. Note that butyl rubber is a copolymer obtained by polymerizing isobutylene and a small amount of isoprene. Note that the halogenated butyl rubber is preferably solid at room temperature (23°C).

[0032] The halogen content in the butyl rubber halide is preferably 0.5% by mass or more, preferably 1% by mass or more, more preferably 1.2% by mass or more, preferably 5% by mass or less, more preferably 4% by mass or less, and still more preferably 3% by mass or less.

[0033] Specific examples of the chlorinated butyl rubber include, for example, Exxon (registered trademark) Chlorobutyl 1066 manufactured by ExxonMobil [halogen content rate: 1.25 wt%, Mooney viscosity: 38 ML 1+8 (125 °C), specific gravity: 0.92], Exxon Chlorobutyl 5066 [halogen content rate: 1.50 wt%, Mooney viscosity: 40 ML 1+8 (125 °C), specific gravity: 0.92]; at least one such as LANXESS X_BUTYL (registered trademark) CB1240 manufactured by LANXESS.

[0034] Specific examples of the brominated butyl rubber include, for example, Exxon Bromobutyl 2211 manufactured by ExxonMobil [halogen content rate: 2.0 wt%, Mooney viscosity: 32 ML 1+8 (125 °C), specific gravity: 0.93], Exxon Bromobutyl 2222 [halogen content rate: 2.0 wt%, Mooney viscosity: 32 ML 1+8 (125 °C), specific gravity: 0.93], Exxon Bromobutyl 2235 [halogen content rate: 2.1 wt%, Mooney viscosity: 39 ML 1+8 (125 °C), specific gravity: 0.93], Exxon Bromobutyl 2244 [halogen content rate: 2.0 wt%, Mooney viscosity: 46 ML 1+8 (125 °C), specific gravity: 0.93], Exxon Bromobutyl 2255 [halogen content rate: 2.1 wt%, Mooney viscosity: 46 ML 1+8 (125 °C), specific gravity: 0.93], Exxon Bromobutyl 6222 [halogen content rate: 2.4 wt%, Mooney viscosity: 32 ML 1+8 (125 °C), specific gravity: 0.93], Exxon Bromobutyl 7211 [halogen content rate: 2.0 wt%, Mooney viscosity: 32 ML 1+8(125 °C), specific gravity: 0.93], Exxon Bromobutyl 7244 [halogen content rate: 2.1 wt%, Mooney viscosity: 46 ML 1+8 (125 °C), specific gravity: 0.93]; at least one such as LANXESS X_BUTYL BBX2 manufactured by LANXESS may be mentioned.

[0035] In the halogenated butyl rubber, a crosslinking reaction occurs in the ultraviolet irradiation step described later, and (a) the elastic modulus of the entire base polymer increases on the rubber surface, making it difficult to deform. As a result, the syringe gasket obtained by the production method of the present invention has a reduced true contact area and a reduced friction coefficient at the contact surface with other articles.

[0036] (a) When the base polymer contains chlorinated butyl rubber or brominated butyl rubber as the halogenated butyl rubber, a crosslinking reaction occurs at the chlorinated or brominated isoprene moiety in the ultraviolet irradiation step described later. (a) When the base polymer contains brominated isobutylene-paramethylstyrene copolymer rubber (BIMS) as the halogenated butyl rubber, a crosslinking reaction occurs at the brominated paramethylstyrene site in the ultraviolet irradiation step described later.

[0037] (a) The base polymer may contain a rubber component other than the halogenated butyl rubber. Examples of other rubber components include nitrile rubbers such as butyl rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, natural rubber, chloroprene rubber, acrylonitrile-butadiene rubber, hydrogenated nitrile rubber, norbornene rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, acrylic rubber, ethylene acrylate rubber, fluororubber, chlorosulfonated polyethylene rubber, epichlorohydrin rubber, silicone rubber, urethane rubber, polysulfide rubber, phosphazene rubber, or 1,2-polybutadiene. These may be used alone or in combination of two or more.

[0038] When using other rubber components, (a) the content of halogenated butyl rubber in the base polymer is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 98% by mass or more. Also, it is a preferred embodiment that (a) the base polymer consists only of halogenated butyl rubber.

[0039] [(b) Resin particles] The volume average particle diameter of (b) the resin particles used in the present invention is preferably 200 μm or less, more preferably 160 μm or less, and even more preferably 120 μm or less. Also, the volume average particle diameter of (b) the resin particles is preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 20 μm or more. This is because when within the above range, it becomes easier to uniformly mix and disperse in the base polymer. Incidentally, the volume average particle diameter of (b) the resin particles can be measured, for example, by the Coulter-Counter method.

[0040] Examples of the resin component constituting (b) the resin particles include polyesters such as polybutylene terephthalate (PBT) and polyethylene terephthalate (PET); polyolefins such as polyethylene (PE) and polypropylene (PP); (meth)acrylic resins; acrylonitrile-butadiene-styrene copolymer (ABS resin); acrylonitrile-styrene copolymer (AS resin); epoxy resins; polyamides (PA); polyurethanes (PU); polyimides (PI); polyphenylene ether (PPE); polysulfone (PSF); polyethersulfone (PES); polyphenylene sulfide (PPS); polyarylate (PAR); polyamideimide (PAI); polyetherimide (PEI); polyetheretherketone (PEEK); polytetrafluoroethylene (PTFE); polyaminobismaleimide (PABM); polybisamidotriazole; polyphenylene oxide (PPO); polyacetal; polycarbonate (PC), and the like.

[0041] The (b) resin particles used in the present invention are preferably polyolefin-based resin particles (resin particles composed of a polyolefin-based resin).

[0042] Since the polyolefin-based resin particles hardly absorb ultraviolet rays (especially ultraviolet rays having a wavelength of 160 nm or more), they do not react in the ultraviolet irradiation step and are exposed on the surface of the rubber constituting the syringe gasket. As a result, in the syringe gasket of the present invention, the true contact area further decreases at the contact surface with other parts, so that the friction coefficient becomes small.

[0043] The polyolefin-based resin is not particularly limited. For example, polyethylene-based resins such as linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), ultra-high molecular weight polyethylene (UHMWPE), and copolymers of ethylene and α-olefins (for example, α-olefins having 3 to 8 carbon atoms); polypropylene-based resins such as polypropylene (PP), propylene-ethylene copolymers, and copolymers of propylene and α-olefins (for example, α-olefins having 4 to 8 carbon atoms); and olefins (for example, olefins having 4 to 8 carbon atoms) such as polybutene, polypentene, and polymethylpentene, alone or as copolymers. These can be used alone or in combination of two or more. The polyethylene-based resin means a resin in which the mass ratio of the repeating unit derived from ethylene in the resin is more than 50% by mass (preferably 70% by mass or more, more preferably 90% by mass or more), and the polypropylene-based resin means a resin in which the mass ratio of the repeating unit derived from propylene in the resin is more than 50% by mass (preferably 70% by mass or more, more preferably 90% by mass or more). Among these, polyethylene-based resins are preferred, low-density polyethylene (LDPE), high-density polyethylene (HDPE), and ultra-high molecular weight polyethylene (UHMWPE) are more preferred, and ultra-high molecular weight polyethylene (UHMWPE) is even more preferred from the viewpoint of more favorably obtaining the effects of the present invention.

[0044] The density of high-density polyethylene (kg / m 3) is 930 kg / m 3 ~960 kg / m 3 is preferable, and 930 kg / m 3 ~950 kg / m 3 is more preferable. The density (kg / m 3 ) of the low-density polyethylene is not particularly limited, but 910 kg / m 3 ~925 kg / m 3 is preferable, and 910 kg / m 3 ~920 kg / m 3 is more preferable.

[0045] In the present invention, as the polyolefin resin particles, it is particularly preferable to use particles made of ultra-high molecular weight polyethylene (UHMWPE). Ultra-high molecular weight polyethylene is generally polyethylene having an average molecular weight of 500,000 or more.

[0046] The viscosity average molecular weight of the ultra-high molecular weight polyethylene (UHMWPE) is not particularly limited, but it is preferably 500,000 or more, more preferably 1,000,000 or more, even more preferably 1,500,000 or more, preferably 8,000,000 or less, more preferably 7,000,000 or less, and even more preferably 6,000,000 or less.

[0047] The viscosity average molecular weight of the ultra-high molecular weight polyethylene (UHMWPE) is measured by measuring the intrinsic viscosity [η] in a decalin solvent at 135 °C, and the value calculated based on the formula: Mν = k[η] α (Mν is the viscosity average molecular weight, and k and α are constants). The intrinsic viscosity is measured by a method conforming to JIS K7367-3 (1999).

[0048] The density of the ultra-high molecular weight polyethylene (UHMWPE) is not particularly limited, but it is preferably 930 kg / m 3 or more, more preferably 932 kg / m 3 or more, even more preferably 934 kg / m 3 or more, and preferably 945 kg / m 3 or less, preferably 943 kg / m 3More preferably, it is as follows, 940 kg / m 3 Even more preferably, it is as follows.

[0049] The melting point of the ultra-high molecular weight polyethylene is preferably 120 °C or higher, more preferably 125 °C or higher, and even more preferably 130 °C or higher. The melting point of the ultra-high molecular weight polyethylene is measured according to ATSM-D3418.

[0050] Specific examples of the particles composed of the ultra-high molecular weight polyethylene (UHMWPE) include, for example, Miporon (registered trademark) PM-200 manufactured by Mitsui Chemicals, Inc. [viscosity average molecular weight: 1.8 million, volume average particle diameter (Coulter-Counter method): 10 μm, density: 938 kg / m 3 , XM-220 [viscosity average molecular weight: 2 million, volume average particle diameter (Coulter-Counter method): 30 μm, density: 937 kg / m 3 , XM-221U [viscosity average molecular weight: 2 million, volume average particle diameter (Coulter-Counter method): 25 μm, density: 937 kg / m 3 , XM-330 [viscosity average molecular weight: 2 million, volume average particle diameter (Coulter-Counter method): 65 μm, density: 937 kg / m 3 , etc.

[0051] (b) The content of the resin particles is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 20 parts by mass or more, preferably 100 parts by mass or less, more preferably 80 parts by mass or less, and even more preferably 70 parts by mass or less with respect to 100 parts by mass of the base polymer component (a). If the content of the resin particles (b) is 5 parts by mass or more, the effect of reducing the friction coefficient by the resin particles (b) is further improved, and if it is 100 parts by mass or less, it becomes easier to uniformly mix and disperse in the base polymer.

[0052] [Other components] The rubber composition preferably contains (c) a crosslinking agent. The (c) crosslinking agent is compounded to crosslink the rubber component contained in the (a) base polymer. As the (c) crosslinking agent, there is no particular limitation as long as it is a crosslinking agent capable of crosslinking the rubber component. Examples of the (c) crosslinking agent include sulfur, metal oxides, resin crosslinking agents, organic peroxides, triazine derivatives, etc., and these can be used alone or in combination of two or more.

[0053] Examples of sulfur used as the crosslinking agent include insoluble sulfur, powdered sulfur, fine powdered sulfur, precipitated sulfur, colloidal sulfur, sulfur chloride, etc.

[0054] Examples of metal oxides used as the crosslinking agent include magnesium oxide, calcium oxide, zinc oxide, copper oxide, etc.

[0055] Examples of resin crosslinking agents include alkylphenol formaldehyde resins such as alkylphenol formaldehyde resins, thermoreactive phenolic resins, phenol dialcohol resins, bisphenol resins, and thermoreactive bromomethylalkylated phenolic resins.

[0056] Specific examples of the organic peroxide include dialkyl peroxide, peroxyester, peroxyketal, hydroperoxide, etc. Examples of the dialkyl peroxide include di(2-t-butylperoxyisopropyl)benzene, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, t-butylcumyl peroxide, di-t-hexyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, etc. Examples of the peroxyester include t-butyl peroxymaleate, t-butyl peroxy-3,3,5-trimethylcyclohexanoate, t-butyl peroxylaurate, t-butyl peroxyisopropyl monocarbonate, t-hexyl peroxybenzoate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-butyl peroxyacetate, t-butyl peroxybenzoate, etc. Examples of the peroxyketal include 1,1-di(t-hexylperoxy)-3,3,5-trimethylcyclohexane, 1,1-di(t-hexylperoxy)cyclohexane, 1,1-di(t-butylperoxy)-2-methylcyclohexane, 1,1-di(t-butylperoxy)cyclohexane, 2,2-di(t-butylperoxy)butane, n-butyl-4,4-di(t-butylperoxy)valerate, 2,2-di(4,4-di(t-butylperoxy)cyclohexyl)propane, etc. Examples of the hydroperoxide include p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, etc. These organic peroxides may be used alone or in combination of two or more kinds.

[0057] Examples of the triazine derivative used as the crosslinking agent include a compound represented by the general formula (1).

[0058] [Chemical formula]

[0059] [wherein, R is -SH, -OR 1 , -SR 2 , -NHR 3 or -NR 4 R 5 (R 1 , R 2 , R 3 , R 4 and R 5 each represent an alkyl group, an alkenyl group, an aryl group, an aralkyl group, an alkylaryl group or a cycloalkyl group. R 4 and R 5 may be the same or different.). M 1 and M 2 are H, Na, Li, K, 1 / 2Mg, 1 / 2Ba, 1 / 2Ca, an aliphatic primary amine, a secondary amine or a tertiary amine, a quaternary ammonium salt or a phosphonium salt. M 1 and M 2 may be the same or different.]

[0060] In general formula (1), examples of the alkyl group include alkyl groups having 1 to 12 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, n-pentyl group, isopentyl group, tert-pentyl group, n-hexyl group, 1,1-dimethylpropyl group, octyl group, isooctyl group, 2-ethylhexyl group, decyl group, or dodecyl group. Examples of the alkenyl group include alkenyl groups having 1 to 12 carbon atoms such as vinyl group, allyl group, 1-propenyl group, isopropenyl group, 2-butenyl group, 1,3-butadienyl group, or 2-pentenyl group. Examples of the aryl group include monocyclic or condensed polycyclic aromatic hydrocarbon groups, and aryl groups having 6 to 14 carbon atoms such as phenyl group, naphthyl group, anthryl group, phenanthryl group or acenaphthylenyl group, etc. Examples of the aralkyl group include aralkyl groups having 7 to 19 carbon atoms such as benzyl group, phenethyl group, diphenylmethyl group, 1-naphthylmethyl group, 2-naphthylmethyl group, 2,2-diphenylethyl group, 3-phenylpropyl group, 4-phenylbutyl group, 5-phenylpentyl group, 2-biphenylylmethyl group, 3-biphenylylmethyl group or 4-biphenylylmethyl group, etc. Examples of the alkylaryl group include alkylaryl groups having 7 to 19 carbon atoms such as tolyl group, xylyl group or octylphenyl group, etc. Examples of the cycloalkyl group include cycloalkyl groups having 3 to 9 carbon atoms such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group or cyclononyl group, etc.

[0061] Specific examples of the triazine derivative represented by the general formula (1) include, for example, 2,4,6-trimercapto-s-triazine, 2-methylamino-4,6-dimercapto-s-triazine, 2-(n-butylamino)-4,6-dimercapto-s-triazine, 2-octylamino-4,6-dimercapto-s-triazine, 2-propylamino-4,6-dimercapto-s-triazine, 2-diallylamino-4,6-dimercapto-s-triazine, 2-dimethylamino-4,6-dimercapto-s-triazine, 2-dibutylamino-4,6-dimercapto-s-triazine, 2-di(iso-butylamino)-4,6-dimercapto-s-triazine, 2-dipropylamino-4,6-dimercapto-s-triazine, 2-di(2-ethylhexyl)amino-4,6-dimercapto-s-triazine, 2-dioleylamino-4,6-dimercapto-s-triazine, 2-laurylamino-4,6-dimercapto-s-triazine or 2-anilino-4,6-dimercapto-s-triazine, or sodium salts or disodium salts thereof.

[0062] Among these, 2,4,6-trimercapto-s-triazine, 2-dialkylamino-4,6-dimercapto-s-triazine, and 2-anilino-4,6-dimercapto-s-triazine are preferable, and 2-dibutylamino-4,6-dimercapto-s-triazine is particularly preferable in terms of easy availability.

[0063] Examples of the triazine derivative also include one or more of, for example, 6-[bis(2-ethylhexyl)amino]-1,3,5-triazine-2,4-dithiol, 6-diisobutylamino-1,3,5-triazine-2,4-dithiol, 6-dibutylamino-1,3,5-triazine-2,4-dithiol, 6-dibutylamino-1,3,5-triazine-2,4-dithiol·monosodium, 6-anilino-1,3,5-triazine-2,4-dithiol, 1,3,5-triazine-2,4,6-trithiol, etc.

[0064] In the rubber composition used in the present invention, as the triazine derivative, one type may be used alone, or two or more types may be used in combination.

[0065] When chlorinated butyl rubber and brominated butyl rubber are used as the rubber components, since the crosslinking mechanisms of the chlorinated butyl rubber and the brominated butyl rubber are different, it is preferable to select and use the crosslinking components optimal for crosslinking. When the rubber composition contains chlorinated butyl rubber as the halogenated butyl rubber, it is preferable to contain a triazine derivative as the (c) crosslinking agent. Further, when the rubber composition contains brominated butyl rubber as the halogenated butyl rubber, it is preferable to contain a metal oxide as the (c) crosslinking agent.

[0066] The content of the (c) crosslinking agent in the rubber composition is preferably 0.2 parts by mass or more, more preferably 0.4 parts by mass or more, still more preferably 0.6 parts by mass or more, preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and still more preferably 10 parts by mass or less with respect to 100 parts by mass of the (a) base polymer component. If the content of the (c) crosslinking agent is within the above range, a rubber having good rubber physical properties (hardness, tensile strength, Cset) and processability (less scorching) can be obtained.

[0067] When chlorinated butyl rubber is used as the halogenated butyl rubber and a triazine derivative is used as the (c) crosslinking agent, the content of the (c) crosslinking agent in the rubber composition is preferably 0.2 parts by mass or more, more preferably 0.4 parts by mass or more, still more preferably 0.6 parts by mass or more, preferably 4 parts by mass or less, more preferably 3 parts by mass or less, and still more preferably 2 parts by mass or less with respect to 100 parts by mass of the (a) base polymer component. If the content of the (c) crosslinking agent is within the above range, a rubber having good rubber physical properties (hardness, tensile strength, Cset) and processability (less scorching) can be obtained.

[0068] As the butyl rubber halide, brominated butyl rubber is used. When a metal oxide is used as the (c) crosslinking agent, the content of the (c) crosslinking agent in the rubber composition is preferably 1 part by mass or more, more preferably 1.5 parts by mass or more, still more preferably 2 parts by mass or more, preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and still more preferably 10 parts by mass or less with respect to 100 parts by mass of the (a) base polymer component. If the content of the (c) crosslinking agent is within the above range, a rubber with good rubber physical properties (hardness, tensile strength, C set) and processability (less scorching) can be obtained.

[0069] The rubber composition preferably does not contain a vulcanization accelerator. This is because the vulcanization accelerator may remain in the final rubber product and elute into the chemical solution in a syringe or the like. Examples of the vulcanization accelerator include guanidine-based accelerators (e.g., diphenylguanidine), thiuram-based accelerators (e.g., tetramethylthiuram disulfide, tetramethylthiuram monosulfide), dithiocarbamate-based accelerators (e.g., zinc dimethyldithiocarbamate), thiazole-based accelerators (e.g., 2-mercaptobenzothiazole, dibenzothiazyl disulfide), and sulfenamide-based accelerators (N-cyclohexyl-2-benzothiazole sulfenamide, N-t-butyl-2-benzothiazole sulfenamide).

[0070] The rubber composition may further contain a (d) acid acceptor. The (d) acid acceptor functions to absorb chlorine-based gases or bromine-based gases generated during the crosslinking of the butyl rubber halide and prevent the occurrence of crosslinking inhibition and the like caused by these gases. In addition, the (d) acid acceptor functions as a scorch inhibitor during the crosslinking of the butyl rubber halide and also prevents the compression set of the syringe gasket from increasing.

[0071] Examples of the (d) acid acceptor include hydrotalcite, metal oxides, metal hydroxides, and the like.

[0072] Examples of the hydrotalcite include Mg 4.5 Al2(OH) 13 CO3·3.5H2O, Mg 4.5 Al2(OH) 13 CO3, Mg4Al2(OH) 12 CO3·3.5H2O, Mg6Al2(OH) 16 CO3·4H2O, Mg5Al2(OH) 14 CO3·4H2O, Mg3Al2(OH) 10 CO3·1.7H2O and other Mg-Al-based hydrotalcites. Examples of the metal oxide include magnesium oxide, calcium oxide, zinc oxide and the like. Examples of the metal hydroxide include calcium hydroxide and the like. These acid acceptors may be used alone or in combination of two or more. Note that the metal oxide used as the crosslinking agent described above may also function as an acid acceptor.

[0073] (d) The content of the acid acceptor is preferably 0.5 part by mass or more, more preferably 1 part by mass or more, preferably 15 parts by mass or less, and more preferably 10 parts by mass or less with respect to 100 parts by mass of the base polymer component (a). If the content of the acid acceptor is within the above range, generation of rust on a mold or the like can be suppressed, and the problem that the raw material itself becomes a white spot foreign matter can be reduced.

[0074] A filler may be further compounded in the rubber composition. Examples of the filler include inorganic fillers such as clay and talc. Among these, the filler is preferably an inorganic filler, and more preferably clay or talc. The filler functions to adjust the rubber hardness of the syringe gasket and also functions to reduce the production cost of the syringe gasket as an extender.

[0075] Examples of the clay include fired clay and kaolin clay. Specific examples of the clay include, for example, SILLITIN (registered trademark) Z manufactured by HOFFMANN MINERAL, SATINTONE (registered trademark) W manufactured by ENGELHARD, NN kaolin clay manufactured by Tsuchiya Kaolin Industry Co., Ltd., PoleStar200R manufactured by Imerys Specialties Japan Co., Ltd., and the like.

[0076] Specific examples of the talc include, for example, Hytron A manufactured by Takehara Chemical Industry Co., Ltd., MICRO ACE (registered trademark) K-1 manufactured by Nippon Talc Co., Ltd., Mistron (registered trademark) Vapor manufactured by Imerys Specialties Japan Co., Ltd., and the like.

[0077] The content of the filler in the rubber composition is preferably set appropriately according to the rubber hardness and the like of the target syringe gasket. The content of the filler in the rubber composition is, for example, preferably 5 parts by mass or more, more preferably 10 parts by mass or more, still more preferably 20 parts by mass or more, preferably 200 parts by mass or less, more preferably 150 parts by mass or less, and still more preferably 100 parts by mass or less with respect to 100 parts by mass of the base polymer component.

[0078] The rubber composition may further be blended with a colorant such as titanium oxide and carbon black, a lubricant such as stearic acid, a processing aid, polyethylene glycol as a crosslinking activator, a process oil, and the like in appropriate proportions.

[0079] At least a part of the surface of the syringe gasket of the present invention may be coated with an inert resin layer.

[0080] The resin constituting the inert resin layer is not particularly limited, but from the viewpoint of obtaining good chemical resistance, at least one fluororesin selected from the group consisting of tetrafluoroethylene-ethylene copolymer (ETFE), polytetrafluoroethylene (PTFE), and polychlorotetrafluoroethylene (PCTFE), or a non-fluororesin can be mentioned.

[0081] Tetrafluoroethylene-ethylene copolymer (ETFE) is a copolymer of ethylene and tetrafluoroethylene in a molar ratio of 30 / 70 to 70 / 30. There is also modified ETFE obtained by copolymerizing other components for the purpose of modification. Examples of other components include fluorine-containing olefins and hydrocarbon-based olefins. Specifically, α-olefins such as propylene and butene, fluorine-containing olefins such as hexafluoropropylene, vinylidene fluoride, perfluorobutylethylene, and trifluorochloroethylene, vinyl ethers such as ethylene vinyl ether, perfluoromethyl vinyl ether, and perfluoropropyl vinyl ether, fluorine-containing acrylates, etc. are copolymerized in an amount of about 2 to 10 mol% to modify ETFE.

[0082] As the modified ETFE, ETFE having a functional group that imparts adhesiveness can be preferably used. Examples of the functional group include carboxyl group, carboxyl anhydride group, epoxy group, hydroxyl group, isocyanate group, ester group, amide group, aldehyde group, amino group, cyano group, carbon-carbon double bond, sulfonic acid group, ether group, etc. Commercially available products of modified ETFE include Fluon AH-2000 manufactured by Asahi Glass Co., Ltd.

[0083] Examples of non-fluorine resins include olefin resins. Examples of the olefin resins include polyethylene resins such as polyethylene, ethylene-propylene copolymer, ethylene-propylene-non-conjugated diene copolymer, ethylene-butene copolymer, ethylene-hexene copolymer, ethylene-octene copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-ethyl acrylate copolymer, chlorinated polyethylene; polypropylene resins such as polypropylene, propylene-ethylene random copolymer, propylene-ethylene block copolymer, chlorinated polypropylene; polybutene, polyisobutylene, polymethylpentene, copolymers of cyclic olefins, etc. Polyethylene (especially ultra-high molecular weight polyethylene (UHMWPE)) is preferred. Further, the olefin resin may contain fluorine.

[0084] [Method for manufacturing syringe gasket] The present invention includes a step of molding a rubber composition containing (a) a base polymer containing halogenated butyl rubber and (b) resin particles into a syringe gasket, and a step of irradiating at least a part of the surface of the syringe gasket with ultraviolet rays. A method for manufacturing a syringe gasket is included, which is characterized by this.

[0085] In the manufacturing method of the present invention, by irradiating the surface of a syringe gasket formed by molding a rubber composition containing (a) a base polymer containing halogenated butyl as a rubber component and (b) resin particles with ultraviolet rays, the surface of the syringe gasket after ultraviolet irradiation satisfies P=(Vmp / V)≧0.25.

[0086] [Molding of syringe gasket] The rubber composition used in the present invention is obtained by kneading (a) a base polymer, (b) resin particles, and other compounding materials added as required. Kneading can be performed using, for example, an open roll, a closed kneader, etc. The kneaded product is preferably molded into a ribbon shape, a sheet shape, a pellet shape, etc., and more preferably into a sheet shape.

[0087] The kneading of (a) the base polymer and (b) the resin particles is preferably carried out at a temperature below the melting point of the (b) resin particles.

[0088] Next, the obtained kneaded product is molded into a syringe gasket. The ribbon-shaped, sheet-shaped, or pellet-shaped kneaded product is press-molded into a desired shape. During pressing, vulcanization (crosslinking reaction) of the rubber composition proceeds. The molding temperature is preferably, for example, 130°C or higher, more preferably 140°C or higher, preferably 200°C or lower, and more preferably 190°C or lower. The molding time is preferably 2 minutes or longer, more preferably 3 minutes or longer, preferably 60 minutes or shorter, and more preferably 30 minutes or shorter. The molding pressure is preferably 0.1 MPa or higher, more preferably 0.2 MPa or higher, preferably 10 MPa or lower, and more preferably 8 MPa or lower.

[0089] When at least a part of the surface of the syringe gasket of the present invention is coated with an inert resin layer, by press-molding in a state where an inert resin film is stacked on a sheet composed of the rubber composition, at least a part of the surface of the syringe gasket is coated with the inert resin layer.

[0090] The thickness of the inert resin film to be used may be appropriately adjusted according to the shape and size of the syringe gasket, but is preferably 10 μm or more, more preferably 20 μm or more, further preferably 30 μm or more, preferably 150 μm or less, more preferably 130 μm or less, and further preferably 110 μm or less. If the thickness of the inert resin film is within the above range, film breakage during product molding and wrinkles or floating defects on the film on the product surface after molding do not occur, and both molding processability and product characteristics can be achieved.

[0091] The arithmetic mean roughness Ra of the inert resin film ranges from 0.01 to 0.03 μm for casting films and extrusion films, and even 0.10 μm for skiving films. By making the surface roughness of the mold 0.03 μm or less, a medical rubber article excellent in liquid tightness and airtightness can be obtained. The lower limit of Ra of the inert film itself is not particularly limited.

[0092] It is preferable to perform a treatment for enhancing the adhesiveness with rubber or the like on the inert resin film. Examples of the treatment for enhancing the adhesiveness include chemical treatment methods, a treatment for roughening the surface of the film, and combinations thereof. Specific examples include sodium treatment, glow discharge treatment, plasma treatment (discharge treatment) under atmospheric pressure or in a vacuum, excimer laser treatment (discharge treatment), and ion beam treatment.

[0093] <UV irradiation step> The method for manufacturing the medical rubber article of the present invention includes a step of irradiating at least a part of the surface of the syringe gasket with ultraviolet rays. The syringe gasket to be irradiated with ultraviolet rays may be formed into the shape of the final syringe gasket, or may be a preform before being formed into the shape of the final syringe gasket.

[0094] The method for irradiating the syringe gasket with ultraviolet rays is not particularly limited. For example, it may be irradiated onto the surface of the syringe gasket using a light source that emits ultraviolet rays.

[0095] The wavelength of the ultraviolet ray is preferably 160 nm or more, more preferably 165 nm or more, and even more preferably 170 nm or more. If the wavelength of the ultraviolet ray is 160 nm or more, the (b) polyolefin resin particles hardly absorb the ultraviolet ray of this wavelength, so they do not react even when irradiated with ultraviolet rays and are scattered on the gasket surface. Further, the upper limit of the wavelength of the ultraviolet ray is not particularly limited, but is preferably 380 nm or less, more preferably 300 nm or less, and even more preferably 200 nm or less. If the wavelength of the ultraviolet ray is 380 nm or less, the energy of the ultraviolet ray becomes high, the crosslinking efficiency of the halogenated butyl rubber becomes high, and it becomes difficult to deform. In addition, low molecular components that cause adhesiveness on the gasket surface are decomposed and evaporated by high-energy ultraviolet rays, and low adhesiveness can be realized. Furthermore, due to the evaporation of the low molecular components, the (b) polyolefin resin particles are exposed on the surface of the syringe gasket. As a result, an island-sea structure having island portions where the (b) polyolefin resin particles are exposed and sea portions made of rubber is formed on the surface of the syringe gasket after ultraviolet irradiation. According to the production method of the present invention, the surface of the syringe gasket becomes rough by ultraviolet irradiation, and the gasket surface after ultraviolet irradiation satisfies P=(Vmp / V)≧0.25.

[0096] Among these, vacuum ultraviolet rays having a wavelength of 200 nm or less are particularly preferable from the viewpoint of further improving the effects of the present invention.

[0097] The light source that emits the ultraviolet rays is not particularly limited as long as it can emit ultraviolet rays in the above wavelength range. For example, a low-pressure mercury lamp, a high-pressure mercury lamp, an excimer lamp, etc. are used. In particular, an excimer lamp is preferable because it has strong energy and the surface can be modified in a relatively short time. The excimer lamp emits ultraviolet rays with different wavelengths depending on the type of discharge gas used. For example, when xenon (Xe2) is used, it emits ultraviolet rays with a central wavelength of 172 nm, when xenon chloride (XeCl) is used, it emits ultraviolet rays with a central wavelength of 308 nm, when xenon bromide (XeBr) is used, it emits ultraviolet rays with a central wavelength of 283 nm, when xenon iodide (XeI) is used, it emits ultraviolet rays with a central wavelength of 253 nm, when argon fluoride (ArF) is used, it emits ultraviolet rays with a central wavelength of 193 nm, when argon bromide (ArBr) is used, it emits ultraviolet rays with a central wavelength of 165 nm, when krypton chloride (KrCl) is used, it emits ultraviolet rays with a central wavelength of 222 nm, and when krypton bromide (KrBr) is used, it emits ultraviolet rays with a central wavelength of 207 nm (also called "excimer UV light"). In the present invention, an excimer lamp that emits vacuum ultraviolet rays with a central wavelength of 200 nm or less is preferable, and an excimer lamp using xenon (central wavelength: 172 nm) is particularly preferable.

[0098] In the ultraviolet ray irradiation step, the integrated illuminance on the surface of the syringe gasket is preferably 1000 mJ / cm 2 or more, more preferably 3000 mJ / cm 2 or more, and even more preferably 5000 mJ / cm 2 or more. If the integrated illuminance on the surface of the syringe gasket is 1000 mJ / cm 2 or more, the crosslinking of the butyl rubber halide is sufficiently carried out, and the low molecular components that cause the adhesiveness of the gasket surface are more easily decomposed. Also, the upper limit of the integrated illuminance on the surface of the syringe gasket is not particularly limited, but it is preferably 50000 mJ / cm 2 or less, more preferably 45000 mJ / cm 2 or less, and even more preferably 40000 mJ / cm 2 or less. When the integrated illuminance on the surface of the syringe gasket is 50000 mJ / cm 2This is because, if the following conditions are met, a balance can be achieved between the lifespan of the irradiation equipment and the efficiency of surface modification. The integrated illuminance on the surface of the syringe gasket refers to the total illuminance (arrival illuminance) of ultraviolet rays reaching the surface of the syringe gasket, which can be calculated by multiplying the intensity of the ultraviolet rays reaching the surface of the syringe gasket (arrival intensity) by the irradiation time of the ultraviolet rays.

[0099] The arrival intensity and irradiation time of the ultraviolet rays may be appropriately adjusted so that the integrated illuminance is within the above-mentioned range. Usually, the arrival intensity of the ultraviolet rays is 10 mW / cm 2 / sec to 100 mW / cm 2 / sec, and the irradiation time is preferably 10 seconds to 5000 seconds. By setting the arrival intensity and irradiation time of the ultraviolet rays within these ranges, it is easier to obtain an integrated illuminance within the above-mentioned range.

[0100] The distance between the surface of the syringe gasket and the light source (lamp) that emits ultraviolet rays is not particularly limited, but from the perspective of enhancing the uniformity of ultraviolet irradiation, it is preferably 1 mm to 20 mm.

[0101] In the present invention, by irradiating at least a part of the surface of the syringe gasket with ultraviolet rays, the surface of the gasket can be greatly modified to have a low coefficient of friction and low adhesiveness.

[0102] In the manufacturing method of the present invention, when at least a part of the surface of the syringe gasket is coated with an inert resin layer, the entire syringe gasket including the inert resin layer may be irradiated with ultraviolet rays, or the exposed rubber surface that is not coated with the inert resin layer may be irradiated with ultraviolet rays. When irradiating the exposed rubber surface with ultraviolet rays, ultraviolet rays may be irradiated only on a part of the exposed rubber surface, or the entire exposed rubber surface may be irradiated with ultraviolet rays.

[0103] For example, when only the top surface of the syringe gasket is coated with an inert resin layer, it is preferable to irradiate only the sliding surface with ultraviolet rays.

[0104] The manufacturing method of the syringe gasket of the present invention may include a step of processing the cured product of the rubber composition into a predetermined shape, a step of washing, a step of sterilizing, and a step of drying. For example, from the cured product of the rubber composition after ultraviolet irradiation, unnecessary parts are cut off and removed to form a predetermined shape, and then washed, sterilized, dried, and packaged to produce a syringe gasket. Note that cutting off and removing unnecessary parts to form a predetermined shape may be performed before irradiating the cured product of the rubber composition with ultraviolet rays.

[0105] From the perspective of SOF regulations, it is preferable that the syringe gasket of the present invention is not coated with silicone oil. Examples of the silicone oil include dimethylpolysiloxane, methylphenylpolysiloxane, and modified products thereof. The syringe gasket of the present invention can achieve a low friction coefficient and low adhesiveness even without using silicone oil.

[0106] Hereinafter, the present invention will be described in detail with reference to the drawings, but the present invention is not limited to the embodiments shown in the drawings.

[0107] FIG. 2 is a diagram showing in an exploded state a medical syringe in which the syringe gasket of the present invention is used, that is, a syringe called a prefilled syringe 30. In FIG. 2, the syringe barrel 31 and the syringe gasket 33 are each shown in a half-sectional view. The prefilled syringe 30 includes a cylindrical syringe barrel 31, a plunger 32 that is combined with the syringe barrel 31 and can reciprocate within the syringe barrel 31, and a syringe gasket 33 attached to the tip of the plunger 32.

[0108] The plunger 32 is composed of, for example, a resin plate piece with a cross-section in a cross shape, and a head portion 38 to which a syringe gasket 33 is attached is provided at its tip. The head portion 38 is made of resin integrally formed with the plunger 32 and is machined into a male screw shape. The syringe gasket 33 has a substantially cylindrical shape with a short axis, and its front end face has, for example, a blunt-angle mountain shape with a protruding axial center portion. And a fitting recess 35 with a female screw shape engraved axially from the rear end face is formed. The head portion 38 of the plunger 32 is screwed into the fitting recess 35 of the syringe gasket 33, whereby the syringe gasket 33 is attached to the tip of the plunger 32.

[0109] Figure 3 is a half-sectional front view of an example of a syringe gasket. The syringe gasket 40 includes a main body 41 composed of a cured product of a rubber composition and an inert resin layer 42 covering a part of the surface of this main body. The syringe gasket 40 has a top surface portion 47 in contact with the chemical solution and a sliding surface portion 46 facing the inner surface of the syringe barrel.

[0110] In the embodiment shown in Figure 3, when the syringe gasket 40 is inserted into the syringe barrel, only the mountain-shaped top surface portion 47 in contact with the chemical solution is covered with the inert resin layer 42. As the inert resin layer 42, for example, a polytetrafluoroethylene film is preferable.

[0111] The sliding surface portion (outer peripheral surface) 46 where the syringe gasket 40 contacts the inner surface of the syringe barrel is not provided with the inert resin layer 42 and is irradiated with ultraviolet rays. The sliding surface portion (outer peripheral surface) 46 has high slidability.

[0112] The syringe gasket 40 has a short cylindrical shape and has a plurality of annular ribs 43, 44, and 45 on the sliding surface portion (outer circumferential surface) 46 of the cylindrical shape. The annular ribs are in sliding contact with the inner circumferential surface of the syringe barrel. The plurality of annular ribs are arranged in the axial direction from the front end surface (top surface portion) 47 to the rear end surface 48 of the syringe gasket. The number of annular ribs is not particularly limited as long as it is 1 or more, but it is preferably 2 or more, more preferably 3 or more, preferably 6 or less, more preferably 5 or less, and even more preferably 4 or less.

[0113] The syringe gasket 40 in FIG. 3 has a first annular rib 43, a second annular rib 44, and a third annular rib 45 from the tip side. The first annular rib 43 at the tip preferably has a radial compression rate of 1% or more, more preferably 2% or more, even more preferably 3% or more, preferably 10% or less, more preferably 9% or less, and even more preferably 8% or less. The compression rate is calculated by the following formula from the outer diameter D1 of the annular rib in the uncompressed state and the inner diameter R of the syringe barrel. Compression rate (%) = 100 × (D1 - R) / D1

[0114] The linear length H1 (the axial length) of the sliding contact portion of the annular rib 43 at the tip is preferably 1% or more, more preferably 3% or more, even more preferably 6% or more, preferably 25% or less, more preferably 20% or less, and even more preferably 15% or less with respect to the linear length Ho (the axial length of the outer circumferential surface) of the cylindrical sliding surface portion (outer circumferential surface).

[0115] The linear length H2 (the axial length) of the sliding contact portion of the second annular rib 44 and the linear length H3 (the axial length) of the sliding contact portion of the third annular rib 45 are each preferably 1% or more, more preferably 2% or more, even more preferably 3% or more, preferably 15% or less, more preferably 14% or less, and even more preferably 13% or less with respect to the linear length Ho (the axial length of the outer circumferential surface) of the outer circumferential surface of the cylindrical shape.

[0116] The syringe gasket may also be referred to as a stopper or a plunger stopper.

Example

[0117] Hereinafter, the present invention will be described in detail by way of examples. However, the present invention is not limited to the following examples, and modifications and embodiments within the scope not departing from the gist of the present invention are all included in the scope of the present invention.

[0118] [Preparation of Rubber Composition and Ultraviolet Irradiation] The materials shown in Table 1 were kneaded at 60 ° C for 20 minutes using an open roll to prepare a rubber composition. After crosslinking the obtained rubber composition under the molding conditions of 170 ° C for 15 minutes, it was punched into a circular slab with a diameter of 28 mm and a thickness of 2 mm to obtain a test piece for ultraviolet irradiation (a cured product of the rubber composition). The test piece for ultraviolet irradiation was irradiated with vacuum ultraviolet rays (wavelength: 172 nm) so as to obtain the integrated illuminance shown in Table 1. Ultraviolet Irradiation Conditions · Irradiation device: Electrodeless excimer 172 nm irradiation device (manufactured by M.D. Com Co., Ltd.) · Distance between the surface of the cured product and the lamp: 7 mm · Arrival intensity of ultraviolet rays: 57.9 mW / cm 2 / sec

[0119]

Table 1

[0120] Details of the compounding materials used are as follows. Chlorinated butyl rubber: Exxon (registered trademark) Chlorobutyl 1066 manufactured by ExxonMobil (chlorine content rate: 1.25 wt%) General-purpose butyl rubber: Exxon (registered trademark) Butyl 268 manufactured by ExxonMobil (degree of unsaturation: 2.30 mol%) Ultra-high molecular weight polyethylene: Mipelon (registered trademark) XM-220 manufactured by Mitsui Chemicals, Inc. (volume average particle diameter: 30 μm, viscosity average molecular weight: 2 million, melting point 136 °C) Triazine derivative: Disnet DB manufactured by Sankyo Kasei Co., Ltd. Sulfur: Insoluble sulfur (Seimi OT) manufactured by Nippon Kouryū Kōgyō Co., Ltd. Zinc oxide: Active zinc white AZO manufactured by Shōdō Chemical Industry Co., Ltd. Magnesium oxide: Mag-Sarat 150s manufactured by Kyowa Chemical Industry Co., Ltd. Dithiocarbamate: Nocceler (registered trademark) ZTC manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0121] [Evaluation method] (1) Analysis of surface roughness Measuring device: Laser microscope VK-X3000 manufactured by Keyence Corporation Scan mode: Laser confocal Objective lens magnification: 50 times Image analysis software: VK-X3000 multi-file analysis application Image processing: Reference plane setting → planar correction (removing undulation: strength 5) Load area ratio: 40%

[0122] (2) Coefficient of friction <Measurement of static and kinetic coefficients of friction> Figure 4 is an explanatory diagram showing a method for measuring the coefficient of friction using a static and kinetic coefficient of friction measuring machine TL201 (manufactured by TAILAB) for a measurement sample (a circular slab with a thickness of 2 mm and a diameter of 28 mm after ultraviolet irradiation). The measurement sample 63 is fixed to the lower stage 64, and a 10 g weight 61 is placed on a dedicated probe attached with a SUS ball 62 having a diameter of 10 mm to bring the surface of the measurement sample 63 into contact with the SUS ball 62. Then, the stage 64 is moved in the direction of the arrow at a speed of 10 mm / second for a distance of 20 mm. The value obtained by dividing the frictional force F generated at that time by the load (vertical resistance) N is defined as the coefficient of friction μ. (μ = F / N) Note that the coefficient divided by the average vertical resistance N1 for a moving distance of 20 mm is defined as the kinetic coefficient of friction, and the coefficient divided by the maximum average vertical resistance N2 for a moving distance of 20 mm is defined as the static coefficient of friction. <Evaluation of static coefficient of friction> The coefficient of static friction was evaluated according to the following evaluation criteria. ○: The coefficient of static friction is less than 1.50. ×: The coefficient of static friction is 1.50 or more. <Evaluation of coefficient of kinetic friction> The coefficient of kinetic friction was evaluated according to the following evaluation criteria. ○: The coefficient of kinetic friction is less than 1.30. ×: The coefficient of kinetic friction is 1.30 or more.

[0123] (3) Adhesion test <Measurement of tack value> Using a testing machine EZ-SX (manufactured by Shimadzu Corporation), the measurement sample prepared above (a circular slab with a thickness of 2 mm and a diameter of 28 mm after ultraviolet irradiation) was fixed to the lower dedicated jig, and the upper metal Φ10 mm SUS probe was pressed against the surface of the measurement sample. After reaching the set pressure (10 N), it was held for 10 seconds, then raised upward at a speed of 10 mm / second, and the peak value of the adhesive force generated between the probe and the measurement sample was defined as the tack value. n = 5 was measured, and the average value of n = 3 excluding the maximum and minimum values was taken as the tack value. <Evaluation of adhesiveness> Adhesiveness was evaluated according to the following evaluation criteria. 〇: The tack value (N) is 0.50 N or less. ×: The tack value (N) exceeds 0.50 N.

[0124] (4) Comprehensive evaluation 〇: The evaluation results of both the coefficient of friction and the adhesiveness are 〇. ×: Either the evaluation result of the coefficient of friction or the evaluation result of the adhesiveness has an ×.

[0125] The measurement results and evaluation results of the coefficient of friction and adhesiveness are shown in Table 1. From Table 1, it can be seen that the syringe gasket of the present invention has a reduced coefficient of surface friction and adhesiveness.

[0126] Figures 5 to 8 are substitute drawings of photographs taken with a laser microscope of the surfaces of the cured products of Rubber Compositions Nos. 1 to 3 and No. 5, which were formed from a rubber composition containing (a) a base polymer containing a rubber component and (b) resin particles, after irradiation with ultraviolet rays. It can be seen that a sea-island structure having island portions where the (b) resin particles are exposed and sea portions made of rubber is formed on the surface of the rubber cured product.

[0127] Figure 9 is a substitute drawing of a photograph taken with a laser microscope of the surface of the cured product of Rubber Composition No. 6, which contains (a) a base polymer containing a rubber component but does not contain (b) resin particles, after irradiation with ultraviolet rays. It can be seen that minute uneven shapes are formed on the surface of the rubber cured product after ultraviolet irradiation. It is considered that due to ultraviolet irradiation, low molecular components are decomposed and evaporated, and at the same time, the formed crosslinked portions remain, forming minute uneven shapes on the surface.

[0128] Figure 10 is a substitute drawing of a photograph taken with a laser microscope of the surface (without ultraviolet irradiation) of the cured product of a rubber composition formed from Rubber Composition No. 7 containing (a) a base polymer containing a rubber component and (b) resin particles. Comparing with Figures 5 to 8, it can be seen that the (b) resin particles are not exposed on the surface of the rubber cured product. Also, since no ultraviolet irradiation has been performed, the surface of the rubber cured product is smooth.

Industrial Applicability

[0129] According to the present invention, it is possible to provide a syringe gasket with reduced surface friction coefficient and adhesiveness.

Explanation of Reference Numerals

[0130] 30: Prefillable syringe, 31: Syringe barrel, 33: Syringe gasket, 40: Syringe gasket, 43, 44, 45: Annular ribs, 47: Top surface portion, 46: Sliding surface portion 46

[0131] A preferred embodiment (1) of the present invention is a syringe gasket formed from a rubber composition containing (a) a base polymer containing a butyl halide rubber and (b) resin particles, wherein at least a part of the surface of the syringe gasket has a core part and a protruding mountain part with respect to the image analysis result obtained when measuring the surface roughness with a laser microscope, and the volume Vmp (mL / m 2 ) of the protruding mountain part with a load area ratio of separating the core part and the protruding mountain part being 40%, and the content V (mass%) of the (a) base polymer in the rubber composition satisfy P=(Vmp / V)≧0.25, which is a syringe gasket characterized by this.

[0132] A preferred embodiment (2) of the present invention is that the syringe gasket has a top surface part in contact with a chemical solution and a sliding surface part facing the inner surface of the syringe barrel when inserted into the syringe barrel, and at least a part of the sliding surface part is the syringe gasket of embodiment (1) that satisfies P=(Vmp / V)≧0.25.

[0133] A preferred embodiment (3) of the present invention is the syringe gasket of embodiment (1) or (2) in which at least a part of the top surface part is coated with an inert resin layer.

[0134] A preferred embodiment (4) of the present invention is the syringe gasket of embodiment (3) in which the inert resin layer is a layer made of a fluororesin.

[0135] A preferred embodiment (5) of the present invention is the syringe gasket of embodiment (3) in which the inert resin layer is a layer made of a non-fluororesin.

[0136] A preferred embodiment (6) of the present invention is the syringe gasket of any one of embodiments (1) to (5) in which the volume average particle diameter of the (b) resin particles is 200 μm or less.

[0137] A preferred embodiment (7) of the present invention is the syringe gasket of any one of embodiments (1) to (6) in which the content of the (b) resin particles is 5 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the (a) base polymer.

[0138] A preferred embodiment (8) of the present invention is the syringe gasket according to any one of embodiments (1) to (7), wherein the halogenated butyl rubber is at least one selected from the group consisting of chlorinated butyl rubber, brominated butyl rubber, and brominated copolymer of isobutylene and p-methylstyrene.

[0139] A preferred embodiment (9) of the present invention is the syringe gasket according to any one of embodiments (1) to (8), wherein the resin particles are polyolefin resin particles.

[0140] A preferred embodiment (10) of the present invention is the syringe gasket according to embodiment (9), wherein the polyolefin resin particles are at least one selected from the group consisting of ultra-high molecular weight polyethylene, high density polyethylene, and low density polyethylene.

[0141] A preferred embodiment (11) of the present invention is a method for manufacturing a syringe gasket, comprising: a step of molding a rubber composition containing (a) a base polymer containing a halogenated butyl rubber and (b) resin particles into a syringe gasket; and a step of irradiating at least a part of the surface of the syringe gasket with ultraviolet rays.

Claims

1. A syringe gasket formed from a rubber composition containing (a) a base polymer containing a halogenated butyl rubber and (b) resin particles, Regarding the image analysis result obtained when measuring the surface roughness of at least a part of the surface of the syringe gasket with a laser microscope, the volume Vmp (mL / m ２ ), and the content V (mass%) of the (a) base polymer in the rubber composition satisfy P = (Vmp / V) ≧ 0.25, and a syringe gasket is characterized by this.

2. The syringe gasket according to claim 1, wherein when inserted into a syringe barrel, the syringe gasket has a top surface portion in contact with a chemical solution and a sliding surface portion facing the inner surface of the syringe barrel, and at least a part of the sliding surface portion satisfies P = (Vmp / V) ≥ 0.

25.

3. The syringe gasket according to claim 2, wherein at least a part of the top surface portion is coated with an inert resin layer.

4. The syringe gasket according to claim 3, wherein the inert resin layer is a layer made of a fluororesin.

5. The syringe gasket according to claim 3, wherein the inert resin layer is a layer made of a non-fluororesin.

6. The syringe gasket according to claim 1, wherein (b) the volume average particle diameter of the resin particles is 200 μm or less.

7. The syringe gasket according to claim 1, wherein (b) the content of the resin particles is 5 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the (a) base polymer.

8. The syringe gasket according to claim 1, wherein the halogenated butyl rubber is at least one selected from the group consisting of chlorinated butyl rubber, brominated butyl rubber, and brominated copolymers of isobutylene and p-methylstyrene.

9. The syringe gasket according to claim 1, wherein (b) the resin particles are polyolefin-based resin particles.

10. The syringe gasket according to claim 9, wherein the polyolefin-based resin particles are at least one selected from the group consisting of ultra-high molecular weight polyethylene, high density polyethylene, and low density polyethylene.

11. A step of molding a rubber composition containing (a) a base polymer containing a halogenated butyl rubber and (b) resin particles into a syringe gasket, and A method for manufacturing a syringe gasket, characterized by including a step of irradiating at least a part of the surface of the syringe gasket with ultraviolet rays.

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