JPH0639927A - Method for manufacturing spherical molded body - Google Patents

Abstract

(57) [Summary] [Structure] Continuous in the vertical direction (especially density gradient of 0.5 x 10 ^-3 or less (however, density difference per unit depth (1 cm)))
Liquid) or a liquid that has a density change of three or more steps
Injecting molding material 28 into 35 to form a ball. [Effect] The molding material does not float or sink more than necessary. It hardens while floating in a position balanced with the liquid, receives uniform force from the entire circumference, and is molded without impact. It will be. Therefore, the obtained spherical state has good sphericity, and there is no difference in shape between lots.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a spherical molded body, for example, a method for manufacturing a ball-shaped movable valve body used in an artificial valve for an artificial heart.

[0002]

2. Description of the Related Art In recent years, during open heart surgery and other operations,
Development of an artificial heart for assisting and temporarily replacing the function of the heart outside the body is in progress.

For example, as shown in FIGS. 11 to 12, an artificial heart as a blood pump device called a sack type is mainly a pressure-resistant (for example, polycarbonate or polyurethane) housing outer case 1, and this housing outer case. It is composed of a flat bag-shaped sack-type blood chamber 2 which is hermetically housed in a case.

A blood introducing tube 3 and a blood discharging tube 4 are formed above the blood chamber 2 so as to communicate with the blood chamber and face upward and substantially parallel to each other. Around the upper portion of the blood chamber portion, a flange portion 5 forming a part of the housing
The flange portion allows the blood chamber to be hermetically housed in the housing outer case 1.

An artificial check valve 28 for preventing backflow of the blood 17 is mounted inside each of the blood introducing tube 3 and the blood discharging tube 4, whereby the blood introducing tube 3 and the blood chamber are connected. The blood 17 introduced into the blood vessel 2 is discharged from the blood discharge tube 4.

For the ejection of blood, a fluid, such as compressed air and decompressed air, is alternately introduced and exhausted through a port 8 provided at the bottom of the housing outer case 1, and the blood chamber is removed as the external pressure of the blood chamber changes. It is made by repeating expansion and contraction.

The cannula 12 and the blood conduits 3 and 4 on the blood chamber 2 side, which are joined to the heart of the living body by an anastomosis, are attached by inserting them from both ends of each connector 13, respectively.

In such a blood pump device, a ball type artificial valve is used as the artificial valve 28 (Japanese Patent Publication Sho-sho).
54-42759). In particular, the ball type has a movable valve made of a ball, and therefore has advantages that it has better durability and less thrombus formation than a disc type artificial valve.

The advantages of the ball type artificial valve are summarized as follows. (1). It is easy to manufacture and has a small number of parts. Molds for molding are also simple and inexpensive.

(2). Ball 28 and connector body 20 during forward flow
Blood 17 flows through a passage 26 formed between the ball 28 and the ball 28, but at this time, since the ball 28 itself is only in contact with the valve seat 21a by a ceiling contact, the ball 28 immediately moves to the valve seat 21b side especially when the backflow occurs. And backflow is prevented. Therefore, the response characteristic is good. In the figure, 23 is a groove-shaped flow passage between the valve seats 21a-21a,
22 and 24 are circular channels.

(3). Despite being entirely made of plastic and rubber, it has relatively good durability.

The ball 28 as described above is usually formed of rubber such as silicone, but its sphericity is extremely important as a movable valve, and if the accuracy is insufficient, it will be particularly between the valve seat and the valve seat during reverse flow. A gap is likely to occur, and it is not possible to sufficiently prevent backflow. For this reason, it is necessary to polish the surface of the ball after molding such as casting and injection molding, but it is generally very difficult to precisely polish rubber.

Therefore, the applicant of the present invention can easily manufacture a spherical molded body such as the ball-shaped movable valve body described in JP-A-1-280456 with high sphericity (hereinafter referred to as prior invention). Proposed.

An embodiment of this prior invention will be described with reference to FIG. 13. A liquid 25 having a specific gravity substantially the same as that of the molding material solution (or the unhardened ball itself) for molding the ball-shaped movable valve body is subjected to convection. While maintaining a constant temperature so as not to occur, a predetermined amount of the ball molding material solution 28 is gently injected from above from an injection needle 27 of a syringe such as a microsyringe.

As the liquid 25, polyvinyl alcohol, carboxymethylcellulose, methylcellulose, polyvinylpyrrolidone, protective colloid such as sodium polyacrylate or a surfactant, and further an inorganic salt (eg sodium polyphosphate) is added. You may use one.

The liquid 25 is preferably kept at 30 to 80 ° C. in order to accelerate the heat polymerization of the molding material solution 28.
It may be at a high temperature as long as it does not cause convection.

The solution 28 to be injected may be a two-part room temperature curing type monomer, for example, a silicone solution, but other polyurethane and epoxy resin monomer solutions (provided that the solvent is water). Other than this) can also be used.

Further, a liquid layer 29 having a specific gravity smaller than that of the liquid is previously present (suspended) on the uppermost portion of the liquid 25,
At the bottom of the liquid, a liquid layer 31 having a specific gravity larger than that of the liquid 25 is previously present (deposited).

The liquid layer 29 is water-soluble and has a boiling point of 60-70.
℃ or higher, such as isopropyl alcohol,
Alcohols such as butyl alcohol are suitable, but other alcohols having a low specific gravity can be used. Also,
As the liquid layer 31, a water-soluble liquid such as glycerin can be used. However, it is desirable that both the liquids 29 and 31 do not dissolve the molding material 28.

The solution 28 injected from the injection needle 27 as described above floats in the liquid 25, but since it has almost the same specific gravity as the liquid 25 in the process of heat polymerization (curing), it is uniform from all directions. Under pressure, it becomes a sphere in a state of weightlessness, and it is hardened as it is. As a result, as shown by the alternate long and short dash line 28 in FIG.
Is molded.

However, in this molding process, since the solution 28 immediately after being injected into the liquid 25 is a monomer, it has a specific gravity smaller than that of the liquid 25 (less than 1) and floats as shown in FIG. Will end up.

However, since the liquid layer 29 exists at the uppermost portion, the floating liquid 28 is prevented from further floating at the position shown in the drawing, and does not move to the outermost surface (that is, the position where it is exposed to the atmosphere). . If the liquid layer 29 does not exist, as shown by the alternate long and short dash line, the liquid layer 29 floats to the outermost surface, and the droplet itself easily bursts due to atmospheric pressure. Therefore, in the presence of the liquid layer 29, the liquid 28 does not go out to the outermost surface, and the polymerization proceeds while maintaining the sphericity.

As the polymerization progresses, the specific gravity of the ball gradually increases until it finally becomes exactly the same as that of the liquid 25, and as described above, it receives the uniform pressure from all directions and stands still to cure.

However, when the polymerization is further progressed by the polymerization, the specific gravity becomes larger than that of the liquid 25 (greater than 1), and the liquid 25 sinks below the liquid 25 as shown by the solid line in FIG.

At this time, a liquid layer having a large specific gravity is provided at the bottom.
Due to the presence of 31 there is a liquid layer 31
It is elastically repelled by (the liquid layer 31 functions as a cushion), and finally hardens while maintaining the sphericity. On the contrary, without the liquid layer 31, the ball 28 hits the hard bottom surface of the container 34 and is deformed as shown by the alternate long and short dash line, and the sphericity is deteriorated.

In this way, the ball 28 having an excellent sphericity can be formed. Also, the smoothness of the surface is very high,
After molding, the ball does not need to be polished. Moreover, as described above, the ball can be molded only by providing the liquid layers 29 and 31.

[0027]

However, although the invention of the prior application has the above-mentioned features, it has been found that there are actually the following points to be improved. That is, in the above, the specific gravity of the liquid 25 needs to be accurately matched to the specific gravity of the molding material solution 28 (for example, 1.0325 is required to be 1.0325), but the accuracy of the generally used hydrometer (lower limit of measurable value) ) Is 0.002, so it is virtually impossible to match the specific gravity.

Therefore, even if the specific gravity is measured with a specific gravity meter, the liquid 25
When the specific gravities of the solution 28 and the solution 28 do not match, they are likely to float or sink immediately after the injection of the solution 28. Also,
Even in the middle position, it floats or sinks over time.

When left to cure in this state, the solution 28 may be deformed by impact rather than the liquid layers 29 and 31 having a cushioning effect, as shown by the chain double-dashed line in FIG. The obtained ball is likely to be a defective product having insufficient sphericity.

[0030]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method capable of stably and easily obtaining a spherical body having a high sphericity.

[0031]

[Means for Solving the Problems] That is, the first aspect of the present invention is to inject a liquid molding material into a predetermined liquid and harden it while floating it to manufacture a spherical molded body, which is continuous with the liquid in the vertical direction. The present invention relates to a method for producing a spherical molded body that forms a uniform density gradient.

In the first invention, the continuous density gradient is a density gradient of 0.5 × 10 ⁻³ or less (however, in the vertical direction, in the floating region of the liquid molding material of the liquid).
The density difference per unit depth (1 cm)) is particularly preferable.

The second aspect of the invention is that when a liquid molding material is poured into a predetermined liquid and cured while floating, a spherical molded body is manufactured. The present invention relates to a method for producing a spherical molded body to be formed.

[0034]

EXAMPLES Examples of the present invention will be described below.

<Embodiment 1> FIGS. 1 and 2 show an embodiment of the first invention. According to this example, in order to mold the ball, the liquid 35 injecting the molding material solution 28,
It is extremely important to form a continuous density gradient in the vertical direction (that is, in the height or depth direction of the liquid 35).

This density gradient is formed in the liquid 35 itself as a linear density change, as shown in FIG. Therefore, for example, even if there is an error that the specific gravity of the solution 28 cannot be measured by the hydrometer because the specific gravity of the solution 28 is 1.0325 and only 0.002 can be measured by the hydrometer (that is, a measurement error in the specific gravity of the solution 28 in the order of 0.0001), The density (specific gravity) of the liquid 35 immediately above and below the injection position of the solution 28 is
It should be consistent with the density (specific gravity) of.

As a result, as long as the density of the solution 28 and the density gradient of the liquid 35 are determined, the injected solution 28 will not float or sink more than necessary, and will be in a position balanced with the liquid 35. It hardens while floating, receives uniform force from the entire circumference, and is molded without impact. This progresses in the curing process after the injection of the solution 28, and even if the specific gravity is small at the beginning, it is balanced just above the injection position, and even if the specific gravity is increased during the progress of the curing reaction, it is balanced just below. It will be.

In this way, the injected solution 28 is molded into a true sphere without causing the floating and sedimentation more than necessary and without the deformation as shown in FIG. This is very advantageous as a ball valve for medical use because the surface of the ball is formed into a smooth surface without unevenness or clogs and there is no difference in shape between lots.

In the above, the density gradient of the liquid 35 can be selected variously, but it is desirable that there is a density difference of 1 × 10 ⁻³ to 1 × 10 ⁻⁴ per unit height (1 cm) of the liquid 35, for example. In particular, the molding material has a density of 1 × 10 ^-2 before and after its polymerization (curing).
Since there are many things that change in the order of, the density change in the order of 10 ^-3 occurs in the intermediate process, and the density difference (gradient) described above is required correspondingly. When the above-mentioned density gradient is determined, the ball is molded under substantially the same conditions even if the type of the solution, the ball, the temperature at the time of molding, or the like changes, so that a ball with a stable sphericity can always be molded.

The liquid 35 may be a single polymer or solution, and may be a protective colloid or surfactant such as polyvinyl alcohol, carboxymethyl cellulose, methyl cellulose, polyvinyl pyrrolidone, sodium polyacrylate, and an inorganic salt ( For example, those obtained by adding sodium polyphosphate) may be used.

The liquid 35 is preferably kept at 30 to 80 ° C. in order to accelerate the heat polymerization of the molding material solution 28.
It may be at a high temperature as long as it does not cause convection.

The solution 28 to be injected may be a two-part room temperature curing type monomer, for example, a silicone solution, but other polyurethane and epoxy resin monomer solutions (provided that the solvent is water). Other than the above), collagen, gelatin, agar can also be used. In short, any combination is possible as long as the liquid 35 and the solution 28 do not mix.

Next, a method of forming a density gradient in the liquid 35 will be described with reference to FIG. First, for the container 34,
The liquid 43 in the container 42 can be
Feed continuously from the bottom of 34. A liquid 47 in a container 46 is continuously supplied to the container 42 by a pump 45 through a conduit 44.

The liquid 43 is adjusted to a relatively large density (specific gravity) in advance by adding a specific gravity adjusting agent such as calcium chloride to an aqueous polyvinyl alcohol solution, and the liquid 47 has a relatively small density (specific gravity). Specific gravity) has been adjusted. The liquid 43 gradually and continuously becomes less dense due to the supply of the liquid 47, and a stirrer 48 is provided at the bottom of the container 42.
After being sufficiently agitated by the above method, it is supplied to the container 34.

Therefore, by balancing the capacities of the pumps 41 and 45 (that is, the mixing ratio of the liquids 43 and 47), the container 34 is gradually fed to the container 34 from its bottom (for example, 300 cc / mi).
An aqueous solution of polyvinyl alcohol can be supplied to reduce the density (at the rate of n 2). In this case, since the aqueous solution has a high viscosity, by slowly supplying the aqueous solution, the layers are laminated in a state in which the densities of the aqueous solutions are continuously changed so that they do not mix with each other. This density gradient can be arbitrarily controlled by the balance between the pumps 41 and 45.

The density gradient may not be formed as shown by the solid line in FIG. 1, but may be changed in a curved manner at the upper and lower parts of the liquid 35 as shown by the one-dot or two-dot chain line in FIG. .

The example of FIG. 3 shows the case where the ball is molded directly in the connector. That is, the connector body 20 is made vertical, the cap 36 is covered on the bottommost portion, and then the liquid 35 having the same density gradient as described above is put into the state shown in the drawing.

In this state, when the solution 28 is injected in the same manner as described with reference to FIG. 1, the density of the solution 28 and the liquid 35 are balanced after the injection, so that the ball 28 of high sphericity can be easily formed in the liquid 25. It can be molded.

Before assembling the ball, the connector body 20
Since it is manufactured, an antithrombotic agent or the like can be applied or processed in advance on the inner surface thereof, so that it is possible to provide an artificial valve in which the inner surface is smoothed and thrombus hardly occurs.

Next, a specific example of continuously forming a density gradient in the liquid 35 by the method shown in FIG. 2 will be described, and based on this, the superiority of the present invention will be specifically described.

It was carried out under the following condition range. Density range: 1.020 to 1.080 Temperature range: 20 to 40 ° C Pump speed: 10 to 500 ml / min Pump speed ratio A / B = 4/1 to 1/4 Solution composition: Water-polyvinyl alcohol solution Specific gravity adjusting solution: Calcium chloride, Sodium chloride, potassium chloride, sucrose aqueous solution

Specifically, the following conditions were adopted. Creation density: 1.020 to 1.060 (1.020 to 1.040 and 1.0
2 types of gradient of 40 to 1.060 are formed) Temperature: 40 ℃ Pump speed: 41 (A) = 30 ml / min, 45 (B) = 15
ml / min Solution composition: 4% polyvinyl alcohol aqueous solution Specific gravity adjustment: sucrose (however, the specific gravity is the initial, density 43 = 1.040, solution 47 = 1.020, and density 43 = 1.060, solution 47) = 1.040.)

In order to confirm whether or not a density gradient was actually formed, solution samples at various positions were taken and the specific gravity was measured. The results are shown in Table 1 below and FIG.

For comparison, the liquid layer is shown in FIG.
The case where 29 and 31 were not provided (Comparative Example 1) and the case where they were provided (Comparative Example 2) were also carried out.

[0055]

The results shown in Table 2 below were obtained for the balls thus formed. However, a good product does not have eccentricity and its surface is smooth. Defective products are those with a large eccentricity (not spherical) or the surface is not smooth.

[0057]

From these results, it can be seen that the non-defective rate of the balls molded according to the first invention is greatly improved.

Next, another specific example of the first invention will be described. That is, in this example, the continuous density gradient (difference in density per unit depth of 1 cm) is set to 0.5 × 10 ⁻³ or less in the liquid molding material floating region of the liquid 35.

It was carried out under the following condition range. Creation density: 1.020 to 1.050 Temperature: 40 ° C Pump speed: 41 (A) = 30 ml / min, 45 (B) = 15
ml / min Solution composition: 4% polyvinyl alcohol solution Specific gravity adjustment: sucrose Depth of liquid 35: Height D in Fig. 1 is 45 cm. Ball molding material 28 and liquids 43 and 47 in Fig. 2 are used for ball molding work. Prior to this, deaeration treatment was previously performed in a reduced pressure atmosphere.

Example 2 The liquid density gradient was set to 0.3393 × 10 ⁻³ . The liquid density measurement results are as shown in FIG. 5 and Table 3 below.

[0062]

The liquid density had a gradient almost as set. After the ball is ejected, it does not float and sink repeatedly.
It floated at a substantially constant position depending on the liquid temperature.

When the balls molded as described above were inspected for sphericity, they were all usable as a movable valve element of a valve for an auxiliary artificial heart.

The sphericity is represented by the ratio R of the maximum diameter to the minimum diameter for one ball. If the ratio R is 1.025681 or less, the result is acceptable, and if the ratio R exceeds this value, it is not acceptable. The above numerical values are empirically determined as the numerical values necessary for the valve having the ball mounted as the movable valve element to perform a satisfactory function as the check valve.

The inspection is carried out using a limit gauge. The design diameter (nominal diameter) of the ball in this example is 16.2 mm,
This has a tolerance of ± 0.1mm. In the range from the minimum allowable diameter to the maximum allowable diameter, a large number of plate-shaped limit gauges having through holes of substantially circular shape with 50 μm intervals are used.

The ball is brought into contact with the through-hole of the limit gauge in various radial directions, and the minimum diameter gauge (passage gauge) through which the ball passes regardless of the radial direction and the maximum diameter gauge (stop gauge) through which the ball does not pass. ) And are selected, and the ratio R is calculated from the through hole diameters of these two gauges. Ratio R is 1.0256
A ball of 81 or less is passed, and a ball exceeding this value is rejected.

The following can be understood from FIG. 5 and Table-3. The liquid density and its gradient are close to the set values, and it is easy to adjust the liquid density during work. Further, the balls have a high temperature dependency, and the density thereof decreases as the temperature rises.

Example 3 Next, an experiment for finding the relationship between the liquid density gradient and the sphericity of the ball will be described.

According to the method described with reference to FIG. 2, the liquid 35 of FIG.
Set the density gradient of the ball 28 as shown in Table 4 below.
Was molded. In Table 4, the gradient is the density gradient from the surface to a depth of 42.5 cm.

[0071]

The molded balls were inspected for sphericity. The number of balls used for the inspection and the pass rate are also shown in Table-4.

The measured values of the density of the liquid 35 at each depth are shown in the table below.
5 to Table-9 and FIGS. 6 to 10.

[0074]

[0075]

[0076]

[0077]

[0078]

From the above experimental results, the following can be understood.

It is preferable that the density gradient is 0.5 × 10 ⁻³ or less. This is achieved by the ball 28, as indicated by the dashed line in FIG.
Is considered to be located on the surface of the liquid 35.

When the density gradient decreases to 0.1 × 10 ^-3 , the pass rate decreases. It is considered that this is because the difference between the maximum density and the minimum density becomes small in the area of the density gradient, and the ball tends to be unable to stop in the vertical direction due to the balance of the density with the liquid.

In the apparatus used for the experiment, the liquid density gradient is good in the range of 0.1 × 10 ⁻³ to 0.5 × 10 ⁻³ with respect to the ball sphericity, and the particularly preferable range is 0.2 × 10 ⁻³ to
It can be seen that it is 0.4 × 10 ^-3 .

If the depth of the density gradient region is increased, the difference between the maximum density and the minimum density in this region can be increased even if the density gradient is decreased. Therefore, a high sphericity pass rate is required. Is possible. That is, the minimum possible value of the density gradient changes depending on the vertical size of the ball forming apparatus.

Next, as a specific example of the second invention, a method of forming a ball by a multi-step density gradient method instead of the continuous density gradient shown in FIG. 1 or 4 will be described.

<Embodiment 4> That is, as the above-mentioned liquid 35, the density is multi-stepped in the height direction (3 steps or more).
Use the one changed to. For example, by intermittently operating the pump system shown in FIG. 2, solutions of various kinds of densities are layered in descending order of density, and a multi-stage density gradient is formed in the same solution layer.

The general conditions were as follows. Density range: 0.8 to 1.4 Temperature range: 20 to 40 ° C Number of density steps: 4 to 21 (3 to 20 steps for density change) Solution composition: water-polyvinyl alcohol Density adjustment: calcium chloride, potassium chloride, sodium chloride

Specifically, the following conditions were adopted. Creation density: 1.038 −1.039 −1.040 −1.041 −1.042 −
1.043 -1.044 -1.046 -1.048 -1.052 -1.060 11-step density difference Temperature: 30 ° C Solution composition: 2% polyvinyl alcohol aqueous solution Specific gravity adjustment: potassium chloride

The results were good as shown in Table 10 below. Here, the non-defective product is a product having no eccentricity and a smooth surface, and the defective product is a product having large eccentricity but not smooth, as in the first embodiment. It is considered that this is because the specific gravity is balanced at an early stage while the molded body floats and sinks due to multi-stage density changes (also shown in FIG. 4).

[0089]

In the above multi-step density gradient, the number of steps of density change must be three or more. Two
The change in step is not different from that in FIG. Density change is 3
The number of stages is preferably 20 or more and 20 or less, more preferably 5 or more and 18 or less. If there are too many steps, it becomes difficult to form a liquid phase of each density.

Although the present invention has been illustrated above, the above-described embodiments can be further modified based on the technical idea of the present invention.

For example, the material, the specific gravity, the charging method and the like of the liquid layer 35 may be variously changed, and the specific gravity, the injection method and the like of the liquid 28 may be similarly changed.

The density gradient of the liquid 35 is not limited to the above-described linear change, but may be changed in a curved shape, or a straight line and a straight line,
Various combinations such as straight line and curved line, curved line and curved line, etc. are possible.

For example, the material, the specific gravity, the charging method, etc. of the liquid layer 35 may be variously changed, and the specific gravity, the injection method, etc. may be similarly changed for the liquid 28. May be replaced with a nozzle having another suitable structure.

[0095]

As described above, according to the present invention, since the molding material is injected into the liquid which is continuous in the vertical direction or has a density change of three or more steps, the molding material is required. It will not float or sink, and will harden while floating in a position balanced with the liquid,
It receives uniform force from the entire circumference and is molded without impact. Therefore, the obtained spherical state has a good sphericity, and the surface is formed into a smooth surface without unevenness or jaggedness, and there is no difference in shape between lots.

[Brief description of drawings]

FIG. 1 is a sectional view and a density gradient showing a ball forming method according to the present invention.

FIG. 2 is a cross-sectional view showing a method of forming a density gradient in the same method.

FIG. 3 is a cross-sectional view showing another ball molding method according to the present invention.

FIG. 4 is a graph showing a specific density gradient according to the first and second inventions.

FIG. 5 is a graph showing another liquid density gradient according to the first invention.

FIG. 6 is a graph showing a liquid density gradient of Experiment 1 according to the first invention.

FIG. 7 is a graph showing a liquid density gradient in the same experiment 2.

FIG. 8 is a graph showing a liquid density gradient in the same experiment 3.

FIG. 9 is a graph showing a liquid density gradient of Experiment 4.

FIG. 10 is a graph showing a liquid density gradient in the same experiment 5.

FIG. 11 is a cross-sectional view of a conventional blood pump device.

FIG. 12 is a sectional view taken along line XIIA-XIIA and XIIB-XIIB in FIG. 11.
It is a line sectional view.

13A and 13B are a cross-sectional view and a density gradient when a ball is formed by a conventional method.

[Explanation of symbols]

 20 Connector (valve body) 27 Injection needle 28 Ball or molding material 35 (gradient density) liquid 43, 47 Density adjusted liquid

Claims (3)

[Claims] 1. A liquid molding material is poured into a predetermined liquid,
A method for producing a spherical molded body, which comprises forming a continuous density gradient in the liquid in the vertical direction when the spherical molded body is produced by curing while floating. 2. A density gradient of 0.5 × 10 ⁻³ or less (however, a density difference per unit depth (1 cm)) is continuously formed in a floating region of a liquid molding material in the vertical direction. 1. The method for producing a spherical molded body according to 1. 3. Injecting a liquid molding material into a predetermined liquid,
A method for producing a spherical molded body, which comprises three or more density changes in the liquid in the vertical direction when the spherical molded body is produced by curing while floating.