JPH1028921A - Liquid agent coater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the liq. agent coater, which is structurally simple and inexpensive to fabricate, by furnishing a valve mechanism to the coater, forcing air easily into the coater when the liq. agent is hardly discharged to increase the pressure in a liq. agent reservoir and restoring a good coating property. SOLUTION: An air hole 13a provided in the partition wall 13 between the cylinder chamber 20 and liq. agent reservoir 10 of a main body 1 is closed by a check valve 3. A piston 6 in the cylinder chamber 20 consists of a large- diameter base 6a, a small-diameter intermediate 6b fitted with an O ring 7 and a head 6c having an falling off protrusion 60, a pressing part projecting outside the cylinder chamber 20 is integrated and energized in the projecting direction by a spring member, the O ring 7 has an inner diameter larger than the outer diameter of the intermediate 6b and has an outer diameter held firmly to the inner periphery of the cylinder chamber 20, the boundary between the base 6a and intermediate 6b forms an annular step 15, the space outside the cylinder chamber 20 is communicated with the exterior, and an air passage 14a is furnished to the head 6c to communicate the inmost space with the gap between the O ring 7 and intermediate 6b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an applicator for liquids such as correction liquids, paint marker inks, adhesives, and cosmetic liquids.
In particular, it relates to a liquid applicator with a valve mechanism.

[0002]

2. Description of the Related Art In a liquid applicator with a valve mechanism of this type, a part of a valve body protrudes from an application port of an application section provided at one end of a liquid storage section. When pressed, the valve element retreats and opens, and the liquid agent inside is drawn out from the application port. However, the outflow property of the liquid material depends on the gravitational effect caused by turning the application side downward at the time of application and the internal pressure of the liquid material container based on the vapor pressure of the liquid component. The internal pressure decreases as the remaining amount decreases, and the internal pressure decreases significantly due to continuous application or repeated application within a short period of time. Often run out of spills,
There has been a problem that smooth application cannot be performed stably.

[0003] Conventionally, the liquid medicine container is formed of a flexible material such as semi-rigid plastic, and the liquid medicine container is pressed and deformed with the valve mechanism opened during application, thereby squeezing the liquid medicine. Those that have been used have been put to practical use. However, in such a liquid applicator, the liquid container is pressed with a finger each time the liquid is applied, and the amount of application is adjusted according to the degree of pressing. Therefore, the operation is cumbersome. Since the gripping portion is soft, the usability is inferior, and an inexpensive metal can cannot be used for the liquid container, so that the manufacturing cost is high.

In recent years, various proposals have been made to provide a mechanism for forcibly pressurizing air into the storage section in order to solve the problem of insufficient flow due to a decrease in the internal pressure of the liquid storage section. These air press-fitting means utilize the fact that the valve mechanism of the application section is a check valve form, and when the cap is fitted in the application section in an airtight sliding state, the compressed air in the cap is applied from the application port. A method in which the liquid material is press-fitted into the liquid container (see Japanese Patent Application Laid-Open
-58090, Japanese Utility Model Laid-Open No. 6-12095),
An air introduction hole and a check valve to seal it are provided at the rear end of the applicator body, and the cap removed from the application part on the front end side during application is fitted to the rear end side in an airtight sliding state to compress. The air in the cap is press-fitted into the liquid medicine container through the vent hole at the rear end (Japanese Utility Model Laid-Open No. 6-16088), and at the rear end of the applicator body provided with the same vent hole and check valve, By knocking the knock cylinder by slidably fitting the knock cylinder in an airtight state, closing the through hole provided at the top end of the knock cylinder with a finger, and knocking.
The compressed air in the knock cylinder is press-fitted into the liquid agent container from the vent hole at the rear end (Japanese Utility Model Laid-Open No. 6-16088).

[0005]

However, in the conventional method of press-fitting air by fitting the cap to the application section, when the internal pressure is largely reduced, the cap is repeatedly checked while the liquid is being discharged. There is a problem that it is necessary to repeat the attachment and detachment, and the operation is very troublesome. Further, in the configuration in which a knock cylinder is provided at the rear end of the conventional applicator body,
During the pressing operation of the knock cylinder, the top end of the through hole is closed with a finger to seal it, and at the time of the return operation, the finger must be released from the through hole to take in outside air into the knock cylinder, which is also troublesome in operation. It is difficult to make the opening and closing of the through-hole by such a finger known to the general user, so that there is a problem that the reliability is lacking.

In view of the above circumstances, the present invention provides a liquid applicator with a valve mechanism, in which when the liquid material becomes difficult to discharge, air is reliably injected into the liquid material container by an extremely simple operation to reduce the internal pressure. It is an object of the present invention to provide a device which can be increased in pressure, can perform continuous air press-fitting without repeating attachment / detachment of a cap, and is structurally simple and can be manufactured at low cost.

[0007]

In order to achieve the above-mentioned object, a first aspect of the present invention is to provide a liquid medicine container having an application port on one end side of a main body, and a valve body for opening and closing the application port. In a liquid applicator that is biased by spring force and partially protrudes outward,
A cylinder chamber is formed on the other end side of the main body, and a ventilation hole provided in a partition wall between the cylinder chamber and the liquid material container is sealed with a check valve from the liquid material container side, and inside the cylinder chamber. A piston is inserted, the piston has a large-diameter base portion forming a gap between the piston and the peripheral surface of the cylinder chamber, and a small-diameter intermediate portion in which an O-ring is movably fitted in the piston axial direction.
A head portion facing the partition wall having a protrusion for preventing the O-ring from being provided on the outer periphery. The pressing portion protruding outside the cylinder chamber is integrated, and the pressing portion is attached by a spring member in the protruding direction of the pressing portion. The O-ring has an inner diameter larger than the outer diameter of the intermediate portion of the piston and has an outer diameter close to the inner peripheral surface of the cylinder chamber, and the boundary between the base and the intermediate portion of the piston is O An annular step portion facing the side surface of the ring is formed, a space outside the piston of the cylinder chamber communicates with the outside, and a space inside the piston inside the piston is defined as the O-ring in the head portion. This adopts a configuration in which a ventilation path is provided to communicate with a gap position between the piston and an intermediate portion.

In the liquid medicine applicator having the above-described structure, when it becomes difficult for the liquid medicine to come out from the application port due to a decrease in the internal pressure of the liquid medicine container, the pressing portion of the piston is pressed with a finger. By this operation, the piston is pushed into the inner side of the cylinder chamber against the bias of the spring member, but in the initial stage, the annular step of the piston comes into close contact with the side surface of the O-ring, so that The inside of the cylinder chamber on the inner back side becomes a sealed space, and then the air in the closed space is compressed as the piston moves integrally with the O-ring, and the pressure seals the ventilation hole of the partition wall. When the check valve is opened, the air in the cylinder chamber is pressed into the liquid material container through the vent hole, and the check valve closes due to antagonism between the inner side of the cylinder chamber and the pressure in the liquid material container.

When the pressing of the pressing portion is released, at the initial stage, the O-ring whose outer periphery is in close contact with the inner periphery of the cylinder chamber does not move, and the piston returns by the urging of the spring member. As a result, the annular step portion of the piston separates from the O-ring, and the retaining projection of the head portion comes into contact with the O-ring. However, since the head portion has an air passage, it is smaller than the piston in the cylinder chamber. The space on the outer side and the space on the inner side communicate with each other through the ventilation gap between the base of the piston and the peripheral surface of the cylinder chamber and the aforementioned ventilation path, so that outside air can flow into the inner space. Then, the piston moves in the projecting direction of the pressing portion together with the O-ring locked by the retaining projection and returns to the original state before the pressing. In this way, since the internal pressure of the liquid agent storage section is increased by air injection, the liquid agent can be smoothly applied in the subsequent application. Further, even when the internal pressure of the liquid agent storage section is extremely low, the internal pressure can be easily and quickly increased by a so-called pump-up method in which the above-described pressing and releasing operations are repeated. It should be noted that such a piston structure itself has been conventionally used for a manual bicycle air pump.

According to a second aspect of the present invention, in the liquid medicine applicator of the first aspect, a coil spring is loaded in a compressed state in the liquid medicine container of the main body, and one end of the coil spring presses the valve element of the check valve. At the same time, the other end side is configured to press a valve body that opens and closes the application port. Therefore, in this liquid applicator, the coil spring serves both as the operating spring of the valve mechanism to which the liquid is applied and the operating spring of the check valve of the air press-fitting portion, and furthermore, the spring receiving member required when the corresponding operating spring is provided. The parts can be omitted, the number of parts can be greatly reduced, and the internal structure of the application part can be remarkably simplified.

According to a third aspect of the present invention, in the liquid medicine applicator according to the second aspect, the valve body that opens and closes the application port is a sphere, and the other end of the coil spring forms a linear portion, and a tip of the linear portion. In this case, the ball is pressed against the surface to be coated. The linear portion of the coil spring is inserted into the inside of the front side, so that the spring force can be reliably applied to the valve body made of a spherical body.

According to a fourth aspect of the present invention, in the liquid medicine applicator according to any one of the first to third aspects, the retaining projection of the head portion is a protruding edge portion along a circumferential direction, and the ventilation path is formed by the projection. Since the configuration including the U-shaped notch formed in the protruding edge portion is adopted, the structure of the piston is simple and can be easily manufactured by molding of synthetic resin or the like.

[0013]

1 to 5 show a liquid applicator according to a first embodiment of the present invention. In the figure, reference numeral 1 denotes a main body made of a hard synthetic resin molded product, and the inside thereof is a liquid agent storage unit 1.
0, and a coating tip 11 made of a metal tube is press-fitted and fixed to one end of the tapering shape so as to protrude outward from the tip of the tapering shape. 12 is open. A cylindrical member 2 made of a hard synthetic resin molding is screwed to the other end of the main body 1 via a screw portion 1a, so that the inner end is separated from the liquid agent container 10 by a partition wall 13 and the outer end is separated. A cylinder chamber 20 having an open side is provided. A vent 13a is formed in the partition 13, and the vent 13a is sealed by fitting the ball valve 3a of the check valve 3 urged by the coil spring 4 in the compressed state from the liquid agent container 10 side. ing.

As shown in FIG. 3, a bag-shaped ball holding portion 11a is formed inside the coating port 12 of the coating tip 11, and a valve element 5 made of a metal ball is provided in the ball holding portion 11a. It is loaded in a loosely fitted state and partly protruding from the application port 12. Thus, as shown in FIG. 1, the coil spring 4 loaded in the liquid material container 10 is
The end opposite to the check valve 3 side forms a straight portion 4a, which is inserted into the tip 11 and presses the valve body 5 from the inside at the tip. Therefore, the application port 12 is always sealed by the valve body 5. A cap (not shown) is fitted to the application side of the main body 1 when not in use.

Reference numeral 6 denotes a piston made of a hard synthetic resin molded product inserted into the cylinder chamber 20 and has a diameter t ₁ (see FIGS. 4 and 5) between the piston and the inner peripheral surface of the cylinder chamber 3. Large base 6a and small diameter middle part 6 fitted with O-ring 7
b, and a head portion 6c facing the partition wall 13 having a circumferential protruding edge portion 60 for preventing the O-ring 7 from coming off on the outer periphery, and a shaft body 15 is integrally protruded from the center of the outer end surface. ing.
The boundary between the base portion 6a and the intermediate portion 6b forms an annular step portion 15 facing the inner side of the cylinder chamber 20, and the projecting edge portion 60 of the head portion 6c has two intermediate portions which are radially opposed to each other. U-shaped notch 14 having a depth reaching the outer surface position of the portion 6b
a is provided.

The O-ring 7 fitted to the intermediate portion 6b of the piston 6 is made of rubber or soft synthetic resin, has an inner diameter larger than the outer diameter of the intermediate portion 6a, and is in close contact with the inner peripheral surface of the cylinder chamber 20. In a state where a gap t ₂ (see FIGS. 2, 4, and 5) is generated between the outer diameter of the intermediate portion 6a and the outer periphery of the intermediate portion 6a,
The intermediate portion 6a is movable in the piston axial direction.

Reference numeral 8 denotes a cylindrical member 2 forming the cylinder chamber 20.
Is a cylindrical closed-end pressing member made of a hard synthetic resin molded product that is externally fitted in a cap shape, and is screwed to the tip of the piston shaft 16 at the center of the end wall 8a to be integrated with the piston 6. A plurality of ventilation holes 17 are provided in the end wall 8a. A compressed coil spring 9 is disposed between the peripheral wall portion 8b of the pressing member 8 and the outer peripheral portion of the tubular member 2, and the piston 6 is integrally formed with the pressing member 8 in the projecting direction by the coil spring 9. That is, while being urged in the direction of pulling out from the cylinder chamber 20, a spring receiving protruding edge portion 2a provided on the outer periphery on the base side of the cylindrical member 2 and a hook-shaped engaging portion provided on the peripheral edge of the opening of the pressing member 8. The protruding limit position is set by engagement with the portion 8c.

In the normal state where the piston 6 and the pressing member 8 are at the protruding limit position, as shown in FIG. 4, the O-ring 7 is formed on the protruding edge 60 of the head 6c of the piston 6 on the side. And the notches 14a,
14a is a gap t ₂ between the O-ring 7 and the intermediate portion 6b.
, The space 20a inside the piston 6 of the cylinder chamber 20 and the space 20b outside the piston 6 have gaps t ₁ , t
₂ and the notches 14a, 14a, and the outer space 20b communicates with the outside through the vent 17 of the pressing member 8.

In the liquid medicine applicator having the above-described structure, the application port of the applicator body 1 is turned downward when applying.
When the more protruding valve element 5 is pressed against the surface to be coated, the valve element 5 is pushed in against the urging of the coil spring 4 to open the valve. Since the liquid medicine in the liquid medicine container 10 flows out from the application port 12, by moving the application destination in this pressed state,
The liquid agent can be smoothly applied on the surface to be coated with the rolling of the valve element 5. However, when it is difficult for the liquid material to come out of the application port 12 due to a decrease in the internal pressure of the liquid material container 10, the pressing member 8 may be pressed with a finger.

That is, when the above-described pressing operation is performed, the piston 6 is pushed into the inner side of the cylinder chamber 20 against the urging of the coil spring 9. since There the close contact with the side surface of the O-ring 7, as shown in FIG. 5, the inner end side of the gap t ₁ between the inner periphery of the outer peripheral and the cylinder chamber 20 of the base portion 6a is closed by the O-ring 7,
The inner space side of the O-ring 7 of the cylinder chamber 20 is a closed space, and the air in the closed space is compressed as the piston 6 moves integrally with the O-ring 7 to the inner side. The check valve 3 that has sealed the ventilation hole 13a of the partition wall 13 is opened, and the air in the cylinder chamber 20 is pressed into the liquid medicine container 10 through the ventilation hole 13a, and the inner side of the cylinder chamber 20 is located. And the pressure of the liquid material container 10 antagonizes, and the check valve 3 is closed.

When the pressing of the pressing member 8 is released,
In the initial stage, the O-ring 7 whose outer periphery is in close contact with the inner periphery of the cylinder chamber 20 does not move, and the piston 6 performs a return operation by the accumulated power of the coil spring 9.
Is separated from the annular step 15 of the piston 6, the inner and outer spaces 20a and 20b sandwiching the piston 6 communicate with each other, and the outside air can flow into the inner space 20b. It moves in the projecting direction together with the stopped O-ring 7 and returns to the original state shown in FIG. Since the internal pressure of the liquid medicine container 10 is increased by this air injection, the liquid medicine can be smoothly applied in the subsequent application. In addition, even when the internal pressure of the liquid material container 10 is extremely low, the internal pressure can be easily and quickly increased by a so-called pump-up method in which the above-described pressing and releasing operations are repeated.

FIGS. 6 and 7 show a liquid applicator according to a second embodiment of the present invention. In this liquid applicator, a round shaft-shaped pressing portion 18 is integrally formed on the outer end side of the piston 6, and a lid member 21 is screwed to an open end of the cylindrical member 2 constituting the cylinder chamber 20. Central opening 2 of lid member 21
1a, the pressing portion 18 protrudes outward with a gap t ₃ around it, and the coil spring 9 is loaded in a compressed state between the inner end of the piston 6, ie, the head portion 6b and the partition wall 13. The other configuration is the same as that of the first embodiment.

In the solution applicator of the second embodiment,
In a normal state in which the pressing member 18 of the piston 6 is at the protruding limit position, as shown in FIG. 6, the O-ring 7 is in contact with the protruding edge portion 14 of the head portion 6c of the piston 6 on the side surface. notch 14a of the edge 60, since the bottom of 14a confronts the gap t ₂ between the O-ring 7 and the intermediate portion 6b, and a space 20b of the inner space 20a and the outer than the piston 6 of the cylinder chamber 20 Gaps t ₁ , t ₂ and notches 14a, 14
communicated by a, also the outer space 20b communicates with the outside by a gap t _3.

When the pressing portion 18 is pressed with a finger, the annular step 15 of the piston 6 comes into close contact with the side surface of the O-ring 7 in the initial stage, and as shown in FIG. ₁ is closed by an O-ring 7 on the inner end side, and the inner back side of the O-ring 7 becomes a sealed space, and as the piston 6 moves to the inner back side integrally with the O-ring 7, The air in the closed space is compressed, and the pressure causes the check valve 3 to open, so that the air in the cylinder chamber 20 is pressed into the liquid medicine container 10 through the vent hole 13a. Next, when the pressing of the pressing member 8 is released, the O-ring 7 does not move in the initial stage, and the piston 6 performs a return operation by the accumulated force of the coil spring 9, and the O-ring 7 separates from the annular step portion 15. The inner and outer spaces 20a, 20b sandwiching each other communicate with each other, allowing outside air to flow into the inner space 20b, and the piston 6 moves in the protruding direction together with the O-ring 7 locked on the protruding edge portion 60, as shown in FIG. Return to the original state. Therefore, the liquid agent container 1
Since the internal pressure of 0 is increased, the liquid agent can be smoothly applied in the subsequent application.

The structure of the liquid applicator according to the present invention is not limited to the above-described first and second embodiments, and various design changes can be made without departing from the spirit of the present invention. For example, according to the first to third aspects of the present invention, the space 20a on the inner side of the piston 6 in the head portion 6c of the piston 6 is
The air passage communicating with the position of the gap t ₂ between the
In addition to the U-shaped notch 14a as in the first and second embodiments, as shown in FIGS. 6b, a through-hole 14b communicating with the outer surface of the piston 6 is formed parallel to the axial direction of the piston. As shown in FIG. 6b, a radial through-hole 14c communicating with the position near the inner end of the O-ring 7 or a plurality of retaining projections for the O-ring 7 instead of the projections 60, 61 as shown in FIG. 14d of valleys between the projections 62.
.. And various other structures. Also,
The number and size of the cutouts 14a, the through holes 14b, the through holes 14c, and the valleys 14d serving as the ventilation paths can be arbitrarily set.

In the liquid applicators of the first and second embodiments, the valve body 5 for opening and closing the application port 12 is a spherical body.
According to the first, second and fourth aspects of the present invention, a configuration in which the valve body 5 has a shaft shape can be adopted. For example, in the configuration of FIG. 11, a tapered valve seat 1b is formed on the inner periphery near the application port 12 of the main body 1, and an axial valve provided with a tapered valve portion 5a fitted to the valve seat 1b. The body 5 has a thin round shaft-shaped tip 5
b is arranged so as to protrude from the application port 12. In this case, the coil spring 4 that presses the valve body 3a of the check valve 3 at one end is entirely coil-shaped, and is engaged with the rear end shaft 5c of the valve body 5 at the other end. The valve body 5 is urged in the protruding direction. Furthermore, in the configuration of claim 1 and claim 4, the valve element 5a for opening and closing the valve element 3a of the check valve 3 and the application port 12 is provided.
Alternatively, a separate coil spring may be used.

On the other hand, various arrangements other than the first and second embodiments are also possible for the spring member for returning the piston 6 to the returning operation. For example, in the configuration using the bottomed cylindrical pressing member 8 as in the first embodiment, the cylinder chamber 2
0, between the outer end of the cylindrical member 2 and the inner surface of the pressing member 8, or between the inner end of the piston 6 and the partition 13 as in the second embodiment. A recess 19 as shown in FIG. 9 is formed in the piston 6 in the second embodiment.
Various arrangement forms, such as loading between the inner bottom of 9 and the partition 13, can be adopted. In addition, in the present invention, the shape and material of the main body 1, the structure of the application portion, the structure for providing the cylinder chamber 20, the structure of the pressing portion of the piston 6, and the space 20 b outside the piston in the cylinder chamber 20 are externally provided. The detailed configuration such as the configuration of the ventilation path to be communicated can be variously modified in addition to the embodiment.

[0028]

According to the first aspect of the present invention, at the time of application, a liquid applicator with a valve mechanism for pressing a valve body partially protruding from an application port on one end side of a liquid material accommodating portion against a surface to be coated to open the valve. When the liquid material becomes difficult to discharge, the air pressure can be increased by injecting air into the liquid material container with a very simple operation, and the internal pressure can be increased. What is provided is one which can perform continuous air injection, is very easy to use, is structurally simple, and can be manufactured at low cost.

According to the second aspect of the present invention, the liquid applicator has a configuration in which the valve element of the check valve and the valve element that opens and closes the application port in the air press-fitting section are pressed by a single coil spring. Therefore, the number of parts is greatly reduced, and the internal structure of the application portion is remarkably simplified, so that a product that can be easily assembled and manufactured at a lower cost is provided.

According to the third aspect of the present invention, in the liquid medicine applicator configured to press both valve bodies with the single coil spring, extremely smooth coating can be performed by a ball-point pen method, and the spherical body of the coating destination can be applied. There is an advantage that the spring force can be reliably applied to the valve body made of

According to the fourth aspect of the present invention, the liquid applicator has an advantage that a piston portion for pressurizing air in particular can be manufactured simply and structurally easily.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view of a liquid medicine applicator according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is an enlarged vertical sectional side view of an application destination of the liquid applicator.

FIG. 4 is a vertical sectional side view of an air press-fitting portion of the liquid applicator in a normal state.

FIG. 5 is a vertical sectional side view of an air press-fitting portion of the liquid applicator at the time of air press-fitting.

FIG. 6 is a vertical sectional side view of an air press-fitting portion in a normal state in a liquid medicine applicator according to a second embodiment of the present invention.

FIG. 7 is a vertical sectional side view of an air press-fitting portion of the liquid applicator at the time of air press-fitting.

FIG. 8 shows another configuration example of the piston used in the liquid agent applicator of the present invention, wherein (A) is a longitudinal side view of the piston,
(B) is a front view of the piston.

FIG. 9 is a longitudinal sectional side view showing still another configuration example of the piston used in the liquid medicine applicator of the present invention.

FIG. 10 is a front view showing still another configuration example of the piston used in the liquid agent applicator of the present invention.

FIG. 11 is an enlarged vertical cross-sectional side view showing another configuration example of the application destination portion in the liquid material applicator of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Main body 3 Check valve 3a Valve body 4 Coil spring 4a Linear part 5 Valve body 6 Piston 6a Base 6b Intermediate part 6c Head part 7 O-ring 8 Pressing member (pressing part) 9 Coil spring (spring member) 10 Liquid material storage part 12 Coating port 13 Partition wall 13a Vent hole 14a U-shaped notch (air passage) 14b Through hole (air passage) 14c Through hole (air passage) 14d Valley (air passage) 15 Annular step 18 Pressing part 20 Cylinder chamber 20a outer space 60 projecting edge than the spatial 20b piston inner back side of the piston (projection for retaining) 61 projecting edge (protrusion for retaining) 62 projecting piece (retaining protrusion) t ₁ piston periphery and a gap between the inner periphery of the outer peripheral and the O-ring in the middle of the gap t ₂ the piston and the inner circumferential surface of the cylinder chamber 3 of the base

Claims (4)

[Claims] 1. A liquid applicator having an application port on one end side of a main body forming a liquid material storage section, and a valve body for opening and closing the application port being urged by a spring force and partially projecting outward. A cylinder chamber is formed on the other end side of the main body, and a vent hole provided in a partition wall between the cylinder chamber and the liquid material container is sealed with a check valve from the liquid material container side and a piston is provided in the cylinder chamber. The piston has a large-diameter base portion that forms a gap between the piston and the peripheral surface of the cylinder chamber, a small-diameter intermediate portion in which an O-ring is movably fitted in the piston axial direction, and A head portion having a protrusion for preventing the O-ring from being opposed to the partition wall, integrating the pressing portion protruding outside the cylinder chamber, and being urged by a spring member in a projecting direction of the pressing portion, The O-ring has an inner diameter larger than the outer diameter of the intermediate portion of the piston. It has an outer diameter that is large and is in close contact with the inner peripheral surface of the cylinder chamber. A boundary between the base and the intermediate part of the piston forms an annular step facing the side surface of the O-ring. And a liquid passage having an outer space communicating with the outside and an air passage provided in the head portion for communicating a space inside the piston with a space between the O-ring and the intermediate portion of the piston. Applicator. 2. A coil spring is loaded in a compressed state into a liquid agent container of a main body, and one end of the coil spring presses a valve element of the check valve, and the other end of the coil spring opens and closes the application port. The liquid medicine applicator according to claim 1, which is pressed. 3. The liquid agent application according to claim 2, wherein the valve body that opens and closes the application port is a sphere, the other end of the coil spring forms a linear portion, and the tip of the linear portion presses the sphere. vessel. 4. The head-retaining projection of the head portion is a ridge extending along a circumferential direction, and the air passage is formed of a U-shaped notch formed in the ridge. A liquid applicator according to any one of the above.