JP7660981B2 - Liquid Squirter - Google Patents

Description

The present invention relates to a liquid ejector.

Some conventional liquid ejectors have a piston with a specially designed shape to ensure smooth pump operation (see, for example, Patent Document 1). Other conventional liquid ejectors have at least one of the piston and cylinder made of a resin containing polyester bonds and polyether bonds to eliminate malfunctions of the piston caused by swelling of the piston (see, for example, Patent Document 2).

JP 2004-230316 A Japanese Patent Application Publication No. 11-138062

However, the invention described in Patent Document 1 above has a limited range of use because the shape of the piston is restricted. Furthermore, while the invention described in Patent Document 2 above is not restricted by the shape of the piston, it is a measure for only a portion of the pump's components, so there is still room for improvement in terms of the pump's resistance to swelling (swelling resistance) and operability as a whole.

The object of the present invention is to provide a liquid ejector that improves the swelling resistance of the entire pump and improves the operability of the pump without changing the shape of the pump's components.

The liquid ejector according to the present invention has a pump that can be attached to the mouth of a container body containing liquid content, and an actuating member that operates the pump. The pump has a cylinder that can be placed inside the mouth of the container, a rod-shaped valve body that can open and close a lower opening formed in the cylinder, a guide member through which the rod-shaped valve body slidably penetrates, a piston through which the guide member penetrates, and a stem that can push down the piston by pushing down the actuating member. The cylinder, the rod-shaped valve body, the guide member, and the stem are made of a material containing polybutylene terephthalate, and the piston is made of a block copolymer of polytetramethylene ether glycol and polybutylene terephthalate.

The liquid ejector according to the present invention preferably has an annular seal formed radially outward by the guide member and the piston.

In the liquid ejector according to the present invention, it is preferable that the liquid content contains mineral oil.

In the liquid ejector according to the present invention, the mineral oil is preferably isododecane and/or isohexadecane.

The liquid content contains alcohol, and the alcohol concentration is preferably in the range of 5% to 40%.

The present invention provides a liquid ejector that improves the swelling resistance of the entire pump and improves the operability of the pump without changing the shape of the pump's components.

This is a cross-sectional view showing a liquid ejector according to one embodiment of the present invention, taken along a cross section including the axis of the container body. The left side of the drawing shows the initial state before the operating member is pressed, and the right side of the drawing shows the ejecting state after the operating member is pressed. FIG. 2 is an enlarged view of FIG. FIG. 11 is a cross-sectional view showing an initial state of a liquid ejector according to a comparative example of the present invention, taken along a cross section including an axis of a container body. 13 is an enlarged cross-sectional view showing a main part of a liquid ejector having an annular seal portion formed on its radially inner side, according to another comparative example of the present invention, taken along a cross section including the axis. FIG.

Below, we will explain a liquid ejector according to one embodiment of the present invention with reference to the drawings.

In the following description, axis O is the center line of liquid ejector 1. In this embodiment, the center line of liquid ejector 1 is coaxial with the center line of the container body and the center line of the liquid ejection container.

In the following description, "up-down direction" refers to the direction extending along axis O. For example, "up" includes the side of the operating member of liquid ejector 1 (the side of the mouth of the liquid ejection container). Also, for example, "down" includes the side of the cylinder of liquid ejector 1 (the side of the bottom of the container body of the liquid ejection container).

In addition, in the following description, the direction extending along the axis O is also referred to as the axial direction, and the direction extending around the axis O is also referred to as the circumferential direction. In addition, in the following description, the direction perpendicular to the axis O is also referred to as the radial direction.

1 discloses a liquid ejection container having a liquid ejector 1 and a container body 20. Referring to FIG. 1, the liquid ejector 1 has a pump 2 that can be attached to the mouth 21 of the container body 20 in which the liquid content (liquid: viscosity does not matter) is accommodated, and an ejection head (operating member) 3 that operates the pump 2. The pump 2 has a cylinder 5 that can be placed inside the mouth 21 of the container body 20, a poppet valve (rod-shaped valve body) 6 that is placed inside the cylinder 5 and can open and close the lower opening A1 formed in the cylinder 5, a guide member 8 that is placed inside the cylinder 5 and through which the poppet valve 6 slidably passes, a piston 9 that is slidably placed inside the cylinder 5 and through which the guide member 8 passes, and a stem 10 that can push down the piston 9 by pushing down the ejection head 3. The cylinder 5, poppet valve 6, guide member 8 and stem 10 are made of a material containing polybutylene terephthalate (hereinafter also referred to as "PBT"), and the piston 9 is made of a material containing a block copolymer of polytetramethylene ether glycol and PBT (hereinafter also referred to as "PTMG block copolymer PBT").

In this embodiment, the container body 20 is a so-called bottle container. The container body 20 has a shoulder portion 22 connected to the mouth portion 21, and the lower end of the body portion (not shown) connected to the shoulder portion 22 is closed by a bottom portion (not shown). A storage space S capable of storing the content liquid is formed inside the container body 20. The storage space S can store the liquid content liquid. An opening A20 that leads to the storage space S is formed inside the mouth portion 21. The container body 20 can be formed, for example, by blow molding using a synthetic resin. However, the manufacturing method of the container body 20 is not limited to blow molding, and various methods can be used to manufacture the container body 20.

In this embodiment, the pump 2 has a suction pipe 4, a cylinder 5, a poppet valve 6, a coil spring 7, a guide member 8, a piston 9, a stem 10, and a mounting cap 11.

In this embodiment, the cylinder 5 can be inserted into the opening A20 formed in the mouth 21 of the container body 20. In this embodiment, the cylinder 5 extends in the vertical direction. A lower end opening A1 (hereinafter also referred to as the "cylinder lower end opening A1") is formed at the lower end of the cylinder 5. In this embodiment, the cylinder 5 is made of PBT. The suction pipe 4 is connected to the cylinder lower end opening A1. In this embodiment, the cylinder 5 communicates with the storage space S of the container body 20 through the suction pipe 4.

The poppet valve 6 closes the cylinder lower opening A1 so that it can be opened. The poppet valve 6 allows the liquid to flow from the suction pipe 4 to the cylinder 5, while preventing the liquid from flowing back from the cylinder 5 to the suction pipe 4. Referring to FIG. 2, in this embodiment, the poppet valve 6 has a valve body (hereinafter also referred to as the "poppet valve body") 6a that opens and closes the cylinder lower opening A1, and a valve shaft (hereinafter also referred to as the "poppet valve shaft") 6b that is connected to the poppet valve body 6a. The poppet valve body 6a is provided with a plurality of spring support protrusions 6c that are arranged at intervals in the circumferential direction on the radial outer side. In this embodiment, the poppet valve 6 is made of PBT.

The coil spring 7 is disposed inside the cylinder 5. The coil spring 7 elastically supports the guide member 8 relative to the cylinder 5. In this embodiment, the coil spring 7 is interposed between the spring support protrusion 6c of the poppet valve 6 and the flange 8b of the guide member 8 described later. As a result, when the liquid contents from the suction pipe 4 flow into the inside of the cylinder 5, the poppet valve 6 operates in a direction to open the cylinder lower opening A1 against the elastic force of the coil spring 7, and when the liquid contents that have flowed into the inside of the cylinder 5 attempt to flow back into the suction pipe 4, the poppet valve 6 operates in a direction to close the cylinder lower opening A1 due to the elastic force of the coil spring 7. The coil spring 7 can be formed of a metal such as stainless steel.

The guide member 8 is a cylindrical member. In this embodiment, an internal passage R3 is formed inside the guide member 8. The poppet valve shaft 6b is arranged in the internal passage R3. In this embodiment, the guide member 8 has a sliding protrusion 8a, a flange (hereinafter also referred to as a "guide flange") 8b, and a guide shaft 8c. The sliding protrusion 8a is formed on the inner peripheral surface of the lower end of the guide member 8. The sliding protrusion 8a can slide up and down relative to the outer peripheral surface of the poppet valve shaft 6b. In this embodiment, a plurality of sliding protrusions 8a are arranged at intervals in the circumferential direction. The guide flange 8b is formed on the radially outer side of the lower end of the guide member 8. In this embodiment, the guide flange 8b guides the guide member 8 in the up and down direction relative to the cylinder 5. In addition, a circulation port A2 is formed in the guide flange 8b. The circulation port A2 connects the cylinder lower opening A1 to the side of the piston 9 arranged above the guide flange 8b. In this embodiment, a plurality of circulation ports A2 are arranged at intervals in the circumferential direction. In this embodiment, the guide member 8 is made of PBT.

The piston 9 is also a cylindrical member. In this embodiment, the piston 9 has an outer cylinder 9a and an inner cylinder 9b. In this embodiment, the piston 9 also has a connecting portion 9c. The connecting portion 9c connects the outer cylinder 9a and the inner cylinder 9b in an annular shape when viewed in the vertical direction. In this embodiment, the piston 9 is formed of PTMG block copolymer PBT.

In this embodiment, the outer cylinder 9a of the piston 9 (hereinafter also referred to as the "piston outer cylinder 9a") is a sliding part relative to the cylinder 5. The piston outer cylinder 9a guides the piston 9 in the up-down direction relative to the cylinder 5. The outer peripheral surface of the piston outer cylinder 9a is in annular contact with the inner peripheral surface of the cylinder 5 in the circumferential direction. As a result, an annular seal portion is formed between the cylinder 5 and the piston 9. In addition, in this embodiment, the guide shaft 8c of the guide member 8 penetrates the inside of the inner cylinder 9b of the piston 9 (hereinafter also referred to as the "piston inner cylinder 9b"). In this embodiment, the guide shaft 8c is disposed radially inwardly and spaced apart from the inner peripheral surface of the piston inner cylinder 9b. As a result, in this embodiment, an internal passage R2 formed in an annular shape is formed between the guide shaft 8c and the piston inner cylinder 9b when viewed in the up-down direction. In addition, in this embodiment, a communication hole A8 is formed in the guide shaft 8c of the guide member 8. The communication hole A8 penetrates the guide shaft 8c. The communication hole A8 connects the internal passage R2 formed between the guide member 8 and the piston 9 to the internal passage R3 formed in the guide member 8.

Furthermore, in this embodiment, the guide member 8 and the piston 9 form an on-off valve that opens and closes between the flow port A2 and the internal passage R2. The on-off valve allows the content liquid to flow from the flow port A2 to the internal passage R2, while preventing the content liquid from flowing back from the internal passage R2 to the flow port A2. In this embodiment, the piston 9 corresponds to the valve body of the on-off valve, and the guide member 8 corresponds to the valve seat of the on-off valve. Specifically, the piston inner cylinder 9b corresponds to the valve body, and the seating portion 8d formed on the upper surface of the guide flange 8b corresponds to the valve seat. In detail, the seating portion 8d is a cylindrical seating portion that protrudes upward from the upper surface of the guide flange 8b. The lower end portion 9b1 of the piston inner cylinder 9b can be brought into contact with and separated from the seating portion 8d. In this embodiment, as shown on the left side of the drawing in FIG. 2, the outer peripheral surface of the lower end portion 9b1 of the piston inner cylinder 9b can be brought into annular contact with the inner peripheral surface of the seating portion 8d in the circumferential direction. As a result, an annular seal portion can be formed between the piston 9 and the guide member 8. In this embodiment, an annular seal portion is formed on the radially outer side by the piston 9 and the guide member 8. In this embodiment, when the piston 9 moves downward relative to the guide member 8, as shown on the left side of FIG. 2, the outer peripheral surface of the lower end 9b1 of the piston inner tube 9b contacts the inner peripheral surface of the seating portion 8d of the guide flange 8b. This makes it possible to block the flow of the content liquid between the flow port A2 and the internal passage R2. Also, in this embodiment, when the piston 9 moves upward relative to the guide member 8, as shown on the right side of FIG. 2, the outer peripheral surface of the lower end 9b1 of the piston inner tube 9b separates from the inner peripheral surface of the seating portion 8d of the guide flange 8b. This makes it possible to allow the flow of the content liquid between the flow port A2 and the internal passage R2.

The stem 10 is also a cylindrical member. In this embodiment, the stem 10 has a stem body 10a and an enlarged portion 10b connected to the stem body 10a. The enlarged portion 10b of the stem 10 (hereinafter also referred to as "stem enlarged portion 10b") forms the lower end of the stem 10, and the stem body 10a forms the upper end of the stem 10. In this embodiment, an internal passage R4 is formed inside the stem body 10a. The upper end of the guide member 8 (the upper end of the guide shaft 8c) is fixed to the lower end of the stem body 10a. This allows the internal passage R3 formed in the guide member 8 to communicate with the internal passage R4 formed in the stem 10. In this embodiment, a rib 10c extending in the vertical direction is formed on the inner peripheral surface of the stem body 10a. In this embodiment, the multiple ribs 10c are arranged at intervals in the circumferential direction.

The stem enlarged portion 10b holds the piston 9 so that it can slide up and down. In this embodiment, the inner peripheral surface of the stem enlarged portion 10b is located radially outward of the inner peripheral surface (internal passage R4) of the stem body 10a. This allows the piston inner tube 9b to be placed between the guide shaft 8c of the guide member 8 and the stem enlarged portion 10b. In this embodiment, the piston inner tube 9b is a sliding part for the stem enlarged portion 10b. The piston inner tube 9b guides the piston 9 in the up and down direction relative to the stem 10. The outer peripheral surface of the upper end portion 9a2 of the piston inner tube 9b is in annular contact with the inner peripheral surface of the stem enlarged portion 10b in the circumferential direction. This forms an annular seal between the piston 9 and the stem 10.

Referring to FIG. 1, the mounting cap 11 is fixed to the upper end of the cylinder 5. The mounting cap 11 covers the upper opening of the cylinder 5. The mounting cap 11 functions as a pump cover of the pump 2. The mounting cap 11 has a mounting portion 11a that is attached to the mouth portion 21 of the container body 20. In this embodiment, the mounting cap 11 is attached by screwing the mounting portion 11a to the mouth portion 21 of the container body 20. In this embodiment, the mounting cap 11 contacts the upper end of the mouth portion 21 of the container body 20 via an annular seal member 12. The mounting cap 11 also has a guide tube 11b. The guide tube 11b extends in the vertical direction and is connected to the mounting portion 11a. Inside the guide tube 11b, a through hole A11 extending in the vertical direction is formed. The stem body 10a of the stem 10 penetrates the through hole A11. As a result, the upper end of the stem 10 protrudes above the mounting cap 11 through the through hole A11.

The ejection head 3 is formed with an ejection port A3 for ejecting the liquid content. The ejection head 3 has a top wall 3a that can be pressed downward, a connection tube 3b that hangs down from the top wall 3a and has an internal passage R6 that leads to the ejection port A3 and can be connected to the stem 10, and a cover tube 3c that hangs down from the top wall 3a, surrounds the connection tube 3b, and surrounds the guide tube 11b.

In this embodiment, the top wall 3a is a plate-shaped top wall. In this embodiment, the top wall 3a is circular when viewed in the vertical direction. However, the shape of the top wall 3a when viewed in the vertical direction is not particularly limited to a circular shape as long as the user can press down the ejection head 3. In addition, the connection tube 3b extends downward from the top wall 3a. An internal passage R5 is formed inside the connection tube 3b. The internal passage R5 is connected to the internal passage R6. Furthermore, the upper end of the stem 10 (the upper end of the stem body 10a) is fixed to the lower end of the connection tube 3b. As a result, the ejection port A3 of the ejection head 3 is connected to the internal passage R4 formed in the stem 10 via the internal passage R5 and the internal passage R6. In this embodiment, the internal passage R6 is formed inside the nozzle 3d. The nozzle 3d protrudes outward in the axial direction beyond the cover tube 3c. However, according to the present invention, the nozzle 3d can be omitted. In this case, the ejection port A3 is formed in the cover tube 3c.

The liquid ejector 1 can eject the liquid contents of the container body 20 to the outside world by driving the pump 2. The pump 2 can be driven by operating the ejection head 3, for example, as follows.

The pump 2 is operated by repeatedly pressing down the ejection head 3 and then releasing the ejection head 3. When the pump 2 is in the initial state, the poppet valve 6 opens the cylinder lower end opening A1, as shown on the left side of FIG. 1. Also, when the pump 2 is in the initial state, the lower end 9b1 of the piston inner cylinder 9b is in contact with the seating portion 8d of the guide member 8, as shown on the left side of FIG. 1.

In this embodiment, when the ejection head 3 is repeatedly pressed down and released, the liquid contents of the container body 20 are introduced into the cylinder 5 from the lower end opening A1 of the cylinder. The liquid contents introduced into the cylinder 5 pass through the flow port A2 of the guide member 8, push the piston 9 upward as shown on the right side of the drawing in FIG. 1, and flow into the internal passage R2 between the guide member 8 and the piston 9. The liquid contents that flow into the internal passage R2 are introduced into the internal passage R3 formed in the guide member 8 through the communication hole A8 formed in the guide member 8. The liquid contents introduced into the internal passage R3 are introduced into the internal passage R5 of the ejection head 3 through the internal passage R4 formed in the stem 10. The liquid contents introduced into the internal passage R5 can be ejected from the ejection port A3 to the outside world through the internal passage R6 of the ejection head 3.

As described above, in the pump 2 of the liquid ejector 1, the cylinder 5, poppet valve 6, guide member 8, piston 9, and stem 10 are in direct contact with the liquid contents and contribute greatly to the operation of the pump 2. If these components absorb the liquid contents and swell, for example, the sliding and sealing properties of the components may be reduced. Therefore, when these components absorb the liquid contents and swell, it has a significant effect on the operability of the pump 2. Examples of the operability of the pump 2 include the discharge amount from the ejection port A3 and the restoration of the ejection head 3 after it is pressed down. In particular, when these components are made of resin, if the liquid contents contain mineral oil, the operability of the pump 2 may be reduced.

On the other hand, PBT (polybutylene terephthalate) has excellent oil resistance. Therefore, if the cylinder 5, poppet valve 6, guide member 8, piston 9 and stem 10 are each made of PBT, the oil resistance to the contents will be improved.

However, when PBT is used for all the above-mentioned components, although the oil resistance is improved, the operability of the pump 2 may be affected. The inventor of the present application, through intensive testing and research, has come to recognize that the cause of this is that when PBT is used for all the above-mentioned components, a large resistance is generated in the sliding parts. Furthermore, the inventor of the present application has found that it is effective to use different materials for the sliding parts to reduce this resistance. In addition, the piston 9 needs to be made of a material that is flexible because it also needs to have sealing properties. For example, a material with a flexural modulus of 1000 MPa or less is suitable. In ordinary pumps, low-density polyethylene (LDPE, flexural modulus of 100 to 700 MPa) is used as the material for the piston 9. When LDPE was used as a material with a flexural modulus that satisfies the above conditions, it became clear that it could not be used for contents with an isododecane concentration of 10% or more.

Therefore, in the liquid ejector 1, the cylinder 5, poppet valve 6, guide member 8, and stem 10 are made of PBT, and the piston 9 is made of PTMG block copolymer PBT. As a result, in the liquid ejector 1, the oil resistance (swelling resistance) of all of the cylinder 5, poppet valve 6, guide member 8, piston 9, and stem 10 can be improved. Therefore, the liquid ejector 1 can suppress the deterioration of the operability of the pump 2 that can occur due to the swelling of these members. In addition, in the liquid ejector 1, the piston 9 is made of PTMG block copolymer PBT, which allows the piston 9 to have flexibility. As a result, in the liquid ejector 1, the sliding property of the piston 9 as well as the sealing property against the cylinder 5 and the guide member 8 can be improved.

In this way, the liquid ejector 1 improves the swelling resistance of the entire pump and improves the operability of the pump. Furthermore, the liquid ejector 1 does not change the shapes of the components of the pump 2 (cylinder 5, poppet valve 6, guide member 8, piston 9, and stem 10). Therefore, the liquid ejector 1 improves the swelling resistance of the entire pump 2 and improves the operability of the pump 2 without changing the shapes of the components of the pump.

The PBT used for the cylinder 5, poppet valve 6, guide member 8, and stem 10 is, for example, "DURANEX 2000 manufactured by Polyplastics Co., Ltd.". The PTMG block copolymer PBT used for the piston 9 is, for example, "NovaDuran 5505s manufactured by Mitsubishi Engineering Plastics Co., Ltd." (flexural modulus of elasticity 900 MPa).

In this embodiment, as shown in FIG. 2, the guide member 8 and the piston 9 form an annular seal on the radially outer side. Referring to FIG. 2 and other figures, an internal passage R2 is formed between the guide member 8 and the piston 9. In this case, if the piston 9 swells, it is considered that not only the sealing between the guide member 8 and the piston 9 but also the flow through the internal passage R2 will be impaired. Therefore, in the case of a configuration in which the piston 9 forms an annular seal on the radially outer side relative to the guide member 8, as in this embodiment, applying the present invention is effective in improving the operability of the pump 2.

The liquid sprayer 1 can also spray the contents such as cosmetics. For example, some cosmetics contain mineral oil. As mentioned above, PBT has excellent oil resistance. For example, the liquid sprayer 1 is effective when used with contents whose mineral oil concentration is in the range of 10% to 80%. In this case, it is even more effective in improving the operability of the pump 2.

Examples of mineral oils contained in the liquid content include isododecane and/or isohexadecane, specifically, isododecane, isohexadecane, or a mixture of isododecane and isohexadecane, i.e., at least one of isododecane and isohexadecane, or other mineral oils. PBT has excellent oil resistance (swelling resistance), particularly against isododecane and isohexadecane. Therefore, in this case, the swelling resistance of the pump 2 is further improved and no decrease in the operability of the pump 2 is observed. Isododecane is contained in, for example, cosmetics. When the liquid content used in the liquid ejector 1 contains isododecane and isohexadecane, the liquid ejector 1 can be used as a cosmetic ejector.

PTMG block copolymer PBT has flexibility, but low resistance to alcohol. Therefore, when the content liquid contains alcohol, it is preferable to select an appropriate alcohol concentration for the content liquid used in the liquid ejector 1. The liquid ejector 1 uses a content liquid with an alcohol concentration in the range of 5% to 40%. In this case, the swelling rate can be suppressed to 1% or less. Therefore, in this case, the swelling resistance of the pump 2 is improved while suppressing the effects of alcohol, and the operability of the pump 2 is not reduced.

However, according to the present invention, if a ring-shaped seal portion is formed on the radial inside of the piston 9 by the guide member 8 and the piston 9, it will malfunction and cannot be used. Figure 3 shows a liquid ejector as a comparison example with the present invention. In this comparison example, as shown in the enlarged view of Figure 3, the inner circumferential surface of the lower end 9b1 of the piston inner cylinder 9b is in annular contact with the outer circumferential surface of the seating portion 8d in the circumferential direction. That is, in this comparison example, the guide member 8 is sealed with the inner circumferential surface of the piston 9. However, in this comparison example, when the piston 9 swells, appropriate sealing may not be achieved. Also, Figure 4 shows an enlarged view of the main part of a liquid ejector as another comparison example with the present invention. In the comparative example of Figure 4, the inner circumferential surface of the lower end 9b1 of the connecting portion 9c of the piston 9 corresponds to the inner circumferential surface of the lower end 9b1 of the piston inner cylinder 9b in Figure 3. In the comparative example of FIG. 4, the upper surface of the guide flange 8b radially outward of the guide shaft 8c is made smooth, and this smooth upper surface corresponds to the seating portion 8d in FIG. 3. That is, in the case of this comparative example, the guide member 8 is also sealed by the inner peripheral surface of the piston. However, in this comparative example, when the piston 9 swells, appropriate sealing may not be performed. That is, in any case where the guide member 8 and the piston 9 form an annular seal portion on the radially inner side of the piston 9, appropriate sealing may not be performed when the piston 9 swells. In contrast, the liquid ejector 1 according to this embodiment seals the guide member 8 by the outer peripheral surface of the piston. When the guide member 8 and the piston 9 form an annular seal portion on the radially outer side of the piston 9 as in the liquid ejector 1 according to this embodiment, appropriate sealing can be performed even if the piston 9 swells.

The above describes a liquid foam ejection container according to one embodiment of the present invention, but the present invention is not limited to the above embodiment and can be modified in various ways within the scope of the claims. For example, as long as the pump 2 has a cylinder 5, a poppet valve 6, a guide member 8, a piston 9, and a stem 10, the internal arrangement of these can be modified in various ways. In addition, the shapes of the components of the pump 2, such as the cylinder 5, the poppet valve 6, the guide member 8, the piston 9, and the stem 10, can also be modified in various ways. Furthermore, the content liquid is preferably a mineral oil, in particular one containing isododecane, isohexadecane, or alcohol, but is not limited to one containing any of these.

The following shows the results of testing the operability of the pump 2 by leaving the guide member 8 and piston 9 of the liquid ejector 1 in a specified liquid for two days, then assembling them to the liquid ejector 1. In this test, "Novaduran 5505s" (flexural modulus 900 MPa, manufactured by Mitsubishi Engineering Plastics) was used as the PTMG block copolymer PBT for the piston 9. Also, "Duranex 2000" (manufactured by Polyplastics) was used as the PBT for the guide member 8. In the table below, ○ indicates that the operability of the pump 2 is good, and × indicates that the operability of the pump 2 is not good. The operability of the pump 2 was evaluated, for example, by the amount of liquid discharged from the ejection port A3 and the restoration of the ejection head 3 after the ejection head 3 is pressed down. Therefore, good operability of the pump 2 also means that the sealing performance inside the pump 2 is improved.

In this test, only the piston 9 was left in a specified sample for two days, and then it was attached to the liquid ejector 1 and the operability of the pump 2 was tested. A liquid with an isododecane concentration of 80% was used as the specified sample. The results are shown in Table 1.

As shown in Table 1, when PTMG block copolymer PBT was used for the piston 9, the swelling rate was suppressed to 1% or less when the isododecane concentration of the sample was in the range of 80%. In addition, the operability of the pump 2 was also good.

In this test, the piston 9 alone was left in a specified sample for two days, and then it was attached to the liquid ejector 1 and the operability of the pump 2 was tested. The specified sample used was a sample in which ethanol was diluted with water. The results of the six tests are shown in Table 2.

As shown in Table 2, when PTMG block copolymer PBT was used for the piston 9, the swelling rate was suppressed to 1% or less when the ethanol concentration of the sample was in the range of 5% to 40%. The operability of the pump 2 was also good. On the other hand, when the ethanol concentration was 50%, the swelling rate exceeded 1% and the operability of the pump 2 was not good either. Therefore, if the contents contain alcohol, it is considered preferable that the concentration of the alcohol is in the range of 5% to 40%. When isododecane was diluted with ethanol, the results were the same as when only ethanol was used, as in this test.

In this test, only the guide member 8 was left on a specified sample for two days, and then it was attached to the liquid ejector 1 and the operability of the pump 2 was tested. The sample used was a sample in which isododecane was diluted with ethanol. The results of the four tests are shown in Table 3.

As shown in Table 3, when PBT was used for the guide member 8, the swelling rate was suppressed to 1% or less when the isododecane concentration of the sample was in the range of 10% to 80%. In addition, the operability of the pump 2 was also good. Therefore, when the contents contain isododecane, no decrease in operability was observed regardless of the concentration.

1: Liquid ejection container, 2: Pump, 3: Ejection head, 4: Suction pipe, 5: Cylinder, 6: Poppet valve (rod-shaped valve body), 7: Coil spring, 8: Guide member, 8a: Sliding projection, 8b: Flange, 8c: Guide shaft, 9: Piston, 9a: Outer cylinder, 9b: Inner cylinder, 9b1: Lower end, 9b2: Upper end, 9c: Connection part, 10: Stem, 11: Mounting cap, 12: Sealing member, 20: Container body, 21: Mouth part

Claims (5)

The container has a pump that can be attached to a mouth of a container body containing a liquid content, and an actuating member that actuates the pump,
The pump includes a cylinder that can be placed inside a mouth of a container, a rod-shaped valve body that can open and close a lower opening formed in the cylinder, a guide member through which the rod-shaped valve body slidably passes, a piston through which the guide member passes, and a stem that can push down the piston by pushing down the operating member,
the cylinder, the rod-shaped valve body, the guide member and the stem are formed of a material containing polybutylene terephthalate (excluding a block copolymer of polytetramethylene ether glycol and polybutylene terephthalate);
A liquid ejector, wherein the piston is formed from a block copolymer of polytetramethylene ether glycol and polybutylene terephthalate. The liquid ejector according to claim 1, in which the guide member and the piston form an annular seal on the radially outer side. A liquid ejector as described in claim 1 or 2, wherein the liquid content contains mineral oil. The liquid ejector of claim 3, wherein the mineral oil is isododecane and/or isohexadecane. A liquid ejector as described in any one of claims 1 to 4, wherein the liquid contains alcohol, and the concentration of the alcohol is in the range of 5% to 40%.