JP4039901B2 - Thermoplastic elastomer plug and manufacturing method thereof - Google Patents

Description

【００２９】
【発明の効果】
複数の射出ゲートを有する金型を用いて熱可塑性エラストマーをキャビティ内に射出充填し、その際、該エラストマーの射出方向及び射出圧を制御して成形される栓体内に内部残留応力を付与して針刺後の自己密閉性と耐液漏れ性を改善することができる。
【図面の簡単な説明】
【図１】２点ゲート金型のキャビティ内に熱可塑性エラストマーを射出充填する場合の樹脂の流動方向（矢印）をＡ−１〜Ａ−４により示す概略平面図。
【図２】４点ゲート金型のキャビティ内に熱可塑性エラストマーを射出充填する場合の樹脂の流動方向（矢印）をＢ−１〜Ｂ−４により示す概略平面図。
【図３】針入部を上部に配置した金型のキャビティ内に熱可塑性エラストマーを射出充填する場合の樹脂の流動方向（矢印）をＣ−１〜Ｃ−４により示す概略側面図。
【図４】針入部を下部に配置した金型のキャビティ内に熱可塑性エラストマーを射出充填する場合の樹脂の流動方向（矢印）をＤ−１〜Ｄ−４により示す概略側面図。
【図５】多段成形法（この場合は２段）により熱可塑性エラストマーを射出充填する場合の操作手順を示す概略説明図。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a container mouth portion of a medicine to be administered to a human body, a medical instrument part, a stopper used as a stopper having elasticity in a medical instrument, particularly a good self-sealing property even after needle sticking, The present invention relates to a medical and medical plug body made of a thermoplastic elastomer having excellent leakage characteristics and a method for producing the same.
[0002]
[Prior art]
In order to hold a medicine by a medicine container, the container part is usually made of glass or plastic material, and the mouth part is usually stoppered with an elastic stopper. The plug is made of natural rubber, isoprene rubber (IR), synthetic rubber such as isobutylene isoprene copolymer (IIR), and a small amount of a crosslinking agent, reinforcing agent, processing aid, etc. It is made by molding over time.
However, in general, since a high-temperature and long-time pressurization process is required to crosslink rubber, a thermoplastic elastomer is used instead of natural rubber or synthetic rubber for the purpose of simplifying this process, and it is heated and melted to cool. Techniques have been proposed for pressing into a mold and forming in a short time.
[0003]
Such thermoplastic elastomer products include hydrogenated derivatives of both monovinyl aromatic hydrocarbons and conjugated diene elastomers, rubber softeners, and gaskets for syringes or olefinic dienes (Japanese Patent Laid-Open No. 61-247460, 61-37242, 63-57661, 63-57662), a sealing material for pharmaceuticals comprising a butadiene-styrene radial butadiene copolymer, an elastomeric polyolefin, and a polyolefin copolymer (Japanese Patent Application Laid-Open No. Sho A). 52-27447, 52-27448), a plug body that can be welded to a plastic container port made of hydrogenated styrene unit butadiene and conjugated diene copolymer unit (Japanese Utility Model Laid-Open No. 61-146250). , 61-146151, 61-24050 ), And the like.
[0004]
However, all of them are still satisfactory in terms of hygiene, physical performance such as needle sticking into the plug, and chemical performance such as the effect on drug alteration, etc. It has not been obtained.
[0005]
In addition, the rubber plug made of thermoplastic elastomer is more susceptible to stress relaxation than the cross-linked rubber plug. In addition to being easily removed, there is a problem that when the needle is pulled out, it takes time until the needle hole is closed, and a so-called liquid leakage phenomenon occurs in which the chemical solution leaks from the hole. Therefore, in order to solve such problems, as described in Japanese Utility Model Publication No. 3-50914 and Japanese Patent Application Laid-Open No. 11-19177, other self-sealing high materials are laminated on the elastomer material. The method of doing was taken.
[0006]
[Problems to be solved by the invention]
However, in the method described in the above-mentioned Japanese Utility Model Publication No. 3-50914 and Japanese Patent Laid-Open No. 11-19177, the number of manufacturing steps is naturally increased, the manufacturing cost increases, and other materials are laminated. Therefore, they may have adhesive problems.
The present invention eliminates the above-mentioned problems of the prior art and provides a medical medical rubber plug made of a thermoplastic elastomer that has good self-sealing properties and excellent liquid leakage resistance even after puncturing for a long time. The purpose is to provide it at low cost.
[0007]
[Means for Solving the Problems]
The above objects can be achieved by the present invention and its embodiments summarized below. (1) When a thermoplastic elastomer is injected into a cavity from two or more resin injection gates of a mold and injection molding of a thermoplastic elastomer plug is performed, the injection direction and injection pressure of the elastomer are controlled and molded. A method for producing a thermoplastic elastomer plug, wherein internal residual stress in an intended direction is applied to the plug.
(2) When injection molding a thermoplastic elastomer plug by injecting a thermoplastic elastomer into a cavity through a resin injection gate of a mold, the injection direction and injection pressure of the elastomer are controlled and the same or similar thermoplasticity. Elastomer injection is repeated multiple times to form a laminated structure, giving internal residual stress in the intended direction within the molded plug body, and generating internal stress by shifting the cooling time of the injected thermoplastic elastomer A method for producing a thermoplastic elastomer, characterized by comprising:
(3) Thermoplastic elastomer plug manufacturing method according to above SL, which comprises using two or more resin injection gate (2).
[0008]
(4) The method for producing a thermoplastic elastomer plug according to the above (1) or (3 ), wherein the injection directions of the elastomer face each other.
[0009]
( 5 ) The above- mentioned ( 3 ) or (4 ) , wherein the elastomer is injected from the two or more resin injection gates in a direction in which the flow of the elastomer hits a central portion in the cavity. A method for producing a thermoplastic elastomer plug of the present invention.
[0010]
( 6 ) When a thermoplastic elastomer is injected into a cavity from a resin injection gate of a mold and a thermoplastic elastomer plug is injection-molded, the injection of the same or similar thermoplastic elastomer is repeated several times to form a laminated structure. And producing an internal stress by shifting the cooling time of the injected thermoplastic elastomer.
( 7 ) A thermoplastic elastomer plug produced by the production method of any one of (1) to ( 6 ) above.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
In general, for medical and medical plugs, pass the standard value by the test method stipulated in the official pharmacopoeia of Japan Pharmacopoeia, etc. Heat resistance to endure, easy to pierce the injection needle from the top surface of the stopper, no leakage of chemical liquid after needle sticking and after removing the needle, no influence on the chemical liquid due to alteration, etc. While high performance is required, it is also important in terms of manufacturing that it can be easily manufactured continuously and economically.
[0012]
Therefore, the thermoplastic elastomer used in the method (1) or (2) according to the present invention needs to satisfy these requirements. Examples thereof include the following olefin copolymer rubber (elastomer) and / or olefin plastics. That is, a preferable resin composition is (a) 1 to 65% by weight of a homopolymer or copolymer obtained by dynamically partially crosslinking an olefin copolymer rubber and / or olefin plastic, and (b) 5 to 75% by weight. A block copolymer consisting of 95 to 35% by weight of (a) a reinforcing agent and 0 to 25% by weight of a conjugated diene compound and / or a polymer of a hydrogenated product of a conjugated diene compound. It is a resin composition comprising a) and (b) as essential components and (c) as an optional component.
[0013]
Examples of the olefin copolymer rubber (a) according to the present invention include ethylene-propylene copolymer rubber (referred to as EPM), ethylene-propylene-nonconjugated diene-terpolymer rubber (referred to as EPDM), ethylene- Examples include 1-butene copolymer rubber, ethylene-1-butene non-conjugated diene multi-component copolymer, polyethylene-butyl rubber graft copolymer, propylene-4-methylpentene copolymer rubber, and the like. It is a typical one.
[0014]
Examples of the olefin-based plastic according to the present invention include polyethylene resins, polypropylene resins, ethylene vinyl acetate copolymers, other homopolymers of α-olefins such as 1-butene, 1-pentene and 4-methyl-1-pentene, or Examples thereof include copolymers of ethylene and one or more of α-olefins, copolymers of ethylene or vinyl esters mainly containing these α-olefins, unsaturated carboxylic acids, or derivatives thereof. .
[0015]
Polyethylene includes low density, medium density, high density, and ultrahigh molecular weight polyethylene. Of these, low density polyethylene or ultrahigh molecular weight polyethylene is preferred.
Polypropylene includes random or block copolymers, and there are isotactic polypropylene and atactic polypropylene. In the present invention, block copolymers are preferred.
[0016]
In addition, polybutylene, polybutene, polybutadiene, butyl rubber, vinyl acetate, and polyisobutylene can be used as peroxy-decomposable polyolefin resins, and mineral oil softeners are not suitable for the present invention. A propylene-1-butene copolymer, polybutadiene, ethylene-propylene copolymer, or the like can also be used.
As the copolymer (a) of the present invention, one or a mixture of two or more selected from the above can be used.
[0017]
The copolymer (b) according to the present invention is a block copolymer of a vinyl aromatic compound and a conjugated diene compound and / or a hydrogenated product of a conjugated diene compound, and the content of the vinyl aromatic polymerization component is 5 to 5. 75% by weight.
Examples of the polymerization component of the vinyl aromatic compound include styrene, α-methylstyrene, vinyltoluene and the like. If the content of the vinyl aromatic polymerization component is less than 5%, it becomes a viscous body, and if it exceeds 75% by weight, it becomes brittle.
[0018]
Examples of the conjugated diene compound include butadiene, isoprene, ethylene-butylene, 2,3-dimethyl-1-butadiene, and 1-3-pentadiene. Examples of the hydrogenated conjugated diene compound include the above. The hydrogenated product can be mentioned.
In the polymer block mainly composed of the conjugated diene compound, the microstructure can be arbitrarily selected. For example, in the polybutadiene block, the 1,2-vinyl bond is 20 to 50%. The number average molecular weight of the hydrogenated block copolymer is 5,000 to 1,000,000, preferably 60,000 to 220,000.
The production method of the block copolymer comprising these vinyl aromatic compound and conjugated diene and / or hydrogenated conjugated diene may be any known technique as long as it can realize the above-described structure. For example, there are methods described in JP-B-40-23798, JP-A-45-20504, JP-A-48-3555, JP-A-61-42554, and JP-B-48-2423.
As the copolymer (b) according to the present invention, commercially available similar products include styrene-ethylene-butadiene copolymer (abbreviated as SEBS), styrene-isoprene block copolymer (abbreviated as SIS), and styrene-butadiene. -There is a block copolymer of styrene (abbreviated as SBS). In particular, in SEBS, there are commercially available products such as trade name “Clayton” (manufactured by Clayton Polymer Co., Ltd.), “Tuffprene” (manufactured by Asahi Kasei Kogyo Co., Ltd.), and these can be used.
[0019]
1-65% by weight of the partially crosslinked copolymer (a) of the present invention and 95-35% by weight of the copolymer (b) are mechanically mixed or, if necessary, of (c) A reinforcing agent is added up to 25% by weight to form a polymer alloy, which is molded into a plug within a short time.
Examples of the reinforcing agent that can be used include white carbon, clay, carbon, silica, synthetic silica, titanium oxide, ultra-high molecular weight polyethylene fine powder, or a surface-treated product thereof.
[0020]
The unique material properties of the thermoplastic elastomer described above cannot be adapted to the properties required for medical and medical use, particularly for infusion plugs, such as liquid leakage, coring, drop-off strength, needle resistance, holding force, etc. Therefore, in the present invention, a product that can meet the above characteristics can be manufactured by constructing the injection conditions and the mold structure at the time of product molding.
[0021]
(I) Mold structure The number of resin injection gates to the mold product part is increased, pressure loss during injection is prevented, and high pressure is maintained up to the end of the cavity. The larger the number of injection gates is, the better. Four are most preferable in terms of balance. In either case, the mold cavity is preferably formed so that the needle insertion portion is on the lower side.
The mold is configured in this way, and it is preferable that internal stress is generated by shifting the time for cooling by forming a laminated structure by injecting thermoplastic elastomers of the same or the same material in several times. That is, in this case, the cooling (injection) time for each layer is preferably shifted. Of course, the injection can be performed once. The rubber plug thus obtained has no sag after needle sticking over a long period of time, has a good self-sealing property, and has excellent liquid leakage resistance. Moreover, its manufacturing cost is low.
[0022]
(Ii) Injection conditions In general, the injection conditions of the thermoplastic elastomer are preferably set as follows. The molding temperature by injection is set to a low temperature at which resin flow is possible, for example, 150 to 220 ° C., preferably 180 to 200 ° C. for SEBS thermoplastic elastomer. The injection speed (molding rate) is preferably set to a low speed at which filling is possible, for example, 0.5 to ⁵ cm ³ / sec, particularly 1 to ³ cm ³ / sec. On the other hand, the injection pressure is preferably set to a high pressure that can be molded, for example, 50 to 300 kg / cm ² , and particularly preferably 100 to 200 kg / cm ² , whereby the product internal pressure can be kept high. These conditions, that is, temperature, speed, and pressure may be set independently, or may be set in combination of at least two.
[0023]
Hereinafter, the method of the present invention will be described in detail with reference to the accompanying drawings.
The resin that has passed through the circular runner and entered the cavity from the resin injection gate forms a flow direction F ₁ , F ₂ or F _{1 to} F ₄ and collides with the center of the cavity (FIG. 1 (A · 1) / 2 (B-1)) The flow is dispersed F ′ to the left and right (FIG. 1 (A · 2) / FIG. 2 (B-2)), and the cavity is filled (FIG. 1 (A-3), FIG. A-4) / F ′ to F ′ ″ shown in FIG. 2 (B-3) and FIG. 2 (B-4)). As the dispersion flow distance at this time is shorter, the pressure loss is smaller. Therefore, the 4-point gate is formed of a resin that maintains higher pressure to the end of the cavity than the 2-point gate, thereby improving the physical properties of the product.
[0024]
Further, when the upper and lower product placement directions in the mold are arranged such that the needle insertion portion is placed in the upper mold, the resin that has entered the cavity from the resin injection gate is directed to the lower part of the cavity by the action of gravity F ₁ , F ₂ ( FIG. 3 (C-1)). And it disperse | distributes and flows from the lower part, and F ', F ", F''' (FIG. 3 (C-2)-FIG. 3 (C-4)), and a resin fluidized layer will be formed conversely in the puncture direction.
However, by arranging the needle insertion part in the lower mold, the resin fluidized bed is formed in order with the direction of the puncture needle (FIGS. 4D-1 to 4D-4). The physical properties are improved.
[0025]
In the case of multi-stage molding corresponding to the above method (2) according to the present invention, it is carried out as shown in FIGS. 5 (F-1) to 5 (F-6).
In the initial molding stage, the slide pin is at the lowest position, and the upper resin filling port gate-2 is closed by the slide pin [FIG. 5 (F-1)]. In this state, the resin that has entered the cavity 1 from the resin filling port gate-1 collides with the central portion of the cavity and forms a resin fluidized bed in the direction of the puncture needle [FIG. 5 (F-2)]. Next, after the thermoplastic elastomer is cooled and cured, by raising the slide pin, the upper resin filling gate 2 is opened, and a cavity 2 is formed between the lower mold and the initial molded product (laminate 1). [FIGS. 5 (F-3) to (F-4)]. The resin that has entered the cavity 2 through the resin filling gate 2 collides with the central portion of the cavity and forms a resin fluidized bed that is different from that in the initial molding [FIGS. 5 (F-5) to (F-6)]. . The shrinkage stress is generated by shifting the cooling time in this way. In the figure, P / L means a parting line.
In the above operation, the flow direction for filling the resin can be implemented so as to be in the direction of FIGS. Therefore, in the embodiment shown in FIG. 5, the generation of internal stress in the plug body is generated synergistically with that in the case of FIGS.
[0026]
Thus, the thermoplastic elastomer resin that has entered the mold cavity from the resin injection gate collides at the center of the cavity and the flow is dispersed to the left and right to fill the cavity. For this reason, the thermoplastic elastomer plug of the present invention is formed in a form that is concentrated and compressed toward the central portion and leaves an internal stress. It has the unexpected effect of being less. That is, in the present invention, the self-sealing property is enhanced by the internal stress.
[0027]
【Example】
The invention will now be described in more detail by way of examples, which are not intended to be limiting.
Using a four-point gate mold having a plan view shown in FIG. B and a side view shown in FIG. D, EPDM (manufactured by EP Rubber Co., Ltd .: EP-57P) and SEBS (manufactured by Kraton Polymer Co., Ltd .: What was blended in a weight ratio of 20:80 was subjected to injection molding to form a plug. The injection conditions were as follows:
Injection temperature: 190 ° C
Injection speed: 2cm ³ / sec
Injection pressure: 160 kg / cm ²
The needle plug test of the molded plug product was performed as shown below to confirm the liquid leakage prevention effect:
As a comparative example, a comparative plug body was formed under the same conditions except that the number of gates was one.
Test method: 1 L of water was put into a plastic bottle, the sample was put on the mouth, and firmly fixed with a jig for liquid leakage test. The plastic bottle is hung with the mouth facing downward, and the plastic needle is stabbed into the sample needle portion for 2 hours, 12 hours, and 24 hours. Thereafter, the needle was withdrawn and the state of liquid leakage was observed.
[0028]
[Table 1]

[0029]
【The invention's effect】
Using a mold having a plurality of injection gates, a thermoplastic elastomer is injected and filled into the cavity, and at that time, an internal residual stress is applied to the molded plug body by controlling the injection direction and injection pressure of the elastomer. The self-sealing property and the liquid leakage resistance after needle stick can be improved.
[Brief description of the drawings]
FIG. 1 is a schematic plan view showing the flow directions (arrows) of a resin when a thermoplastic elastomer is injected and filled into a cavity of a two-point gate mold by A-1 to A-4.
FIG. 2 is a schematic plan view showing flow directions (arrows) of a resin when indicated by B-1 to B-4 when a thermoplastic elastomer is injected and filled into a cavity of a four-point gate mold.
FIG. 3 is a schematic side view showing the flow direction (arrows) of the resin when the thermoplastic elastomer is injection-filled into the cavity of the mold having the needle insertion portion disposed at the upper side, as indicated by C-1 to C-4.
FIG. 4 is a schematic side view showing the resin flow directions (arrows) D-1 to D-4 when a thermoplastic elastomer is injected and filled into a cavity of a mold having a needle insertion portion disposed below.
FIG. 5 is a schematic explanatory view showing an operation procedure when injection-filling a thermoplastic elastomer by a multi-stage molding method (in this case, two stages).

Claims (7)

Injecting a thermoplastic elastomer into a cavity from two or more resin injection gates of a mold and injection molding a thermoplastic elastomer plug, the injection direction and injection pressure of the elastomer are controlled to form the plug. A method for producing a thermoplastic elastomer plug, comprising applying an internal residual stress in an intended direction.   When the thermoplastic elastomer is injected into the cavity from the resin injection gate of the mold and the thermoplastic elastomer plug is injection molded, the injection direction of the elastomer and the injection pressure are controlled and the injection of the same or similar thermoplastic elastomer is performed. A plurality of times to form a laminated structure, to give internal residual stress in the intended direction in the plug body to be molded, and to generate internal stress by shifting the cooling time of the injected thermoplastic elastomer A method for producing a thermoplastic elastomer. The method for producing a thermoplastic elastomer plug according to claim 2 , wherein two or more resin injection gates are used. Thermoplastic elastomer plug manufacturing method according to claim 1 or 3, characterized in that face each other injection direction of the elastomer. The thermoplastic elastomer plug according to claim 3 or 4 , wherein the elastomer is injected from the two or more resin injection gates in a direction in which the flow of the elastomer hits a central portion in the cavity. Manufacturing method.   When the thermoplastic elastomer is injected into the cavity from the resin injection gate of the mold and the thermoplastic elastomer plug is injection molded, the injection of the same or the same type of thermoplastic elastomer is repeated multiple times to form a laminated structure and injection A method for producing a thermoplastic elastomer, characterized in that an internal stress is generated by shifting a cooling time of the formed thermoplastic elastomer. Thermoplastic elastomer plug prepared by any of the manufacturing method according to claim 1-6.

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