JPH09239801A - How to make balloon tubes - Google Patents

Abstract

(57) Abstract: [PROBLEMS] To industrially produce a thin tube for balloon having good extrusion moldability, suitable tensile strength, elongation and permanent elongation as a balloon, and good thickness accuracy. SOLUTION: A urethane prepolymer is prepared by heating a composition containing a urethane prepolymer and an extender and having a molar ratio of isocyanate group / functional group that reacts with an isocyanate group to more than 1 and 2 or less. React with an extender,
The viscosity of the reaction product is 50,000 to 2,000,000.
For a balloon characterized by being extrusion-molded immediately after reaching a state of 0 cp and then heating the extruded reaction product to complete the reaction between the unreacted urethane prepolymer and the extender and to cross-link allophanate. How to make a tube.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a balloon tube. More specifically, it relates to a method for industrially producing a balloon tube having favorable tensile properties and good thickness accuracy.

[0002]

2. Description of the Related Art A balloon catheter using a polyurethane balloon has already been proposed. This polyurethane balloon is manufactured by cutting a polyurethane tube into a required length. Polyurethane balloon tubes are required to be thin and have high thickness accuracy, and have been conventionally manufactured by a dip molding method. In the tube formed by the dip molding method, the film thickness changes depending on the immersion depth when the mold is immersed, and it is difficult to obtain a tube having a uniform film thickness, and the thickness accuracy is low. Further, while the balloon used for the balloon catheter is very small, the amount of the polyurethane solution stored in the dipping bath is large, which is generally economically disadvantageous in many cases.

Extrusion of polyurethane is a common practice. In the conventional extrusion molding, polyurethane is used as pellets and then subjected to extrusion molding. However, cross-linked polyurethanes such as allophanate cross-links cannot be extruded. Further, in the case of a highly reactive polyurethane having residual isocyanate groups, it is difficult to control the permanent elongation, tensile strength, etc. of the extruded product to desired values when extruding after pelletization. Therefore, it is difficult to stably manufacture a balloon tube having desired tensile properties by extrusion molding.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for industrially producing a thin and highly accurate balloon tube having a tensile strength, elongation and permanent elongation suitable for a balloon. Especially. The present inventors have found that when pelletizing a reactive polyurethane, the isocyanate group reacts with moisture in the air to lose the reactive activity and affects physical properties such as permanent elongation, and the urethane polymer and the extender. It was found that such difficulty can be avoided by reacting with and extruding immediately after reaching a predetermined viscosity, then heating the extrudate to complete the reaction and cross-linking with allophanate, and based on this finding The present invention has been completed.

[0005]

Thus, according to the present invention, the urethane prepolymer and the extender are contained, and the molar ratio of the isocyanate group / the functional group which reacts with the isocyanate group exceeds 1, The composition of 2 or less is heated to react the urethane prepolymer with the extender, and the mixture is extruded immediately after the viscosity of the reaction product reaches a state of 50,000 to 2,000,000 cp. A method for producing a balloon tube is provided, which comprises heating an extruded reaction product to complete the reaction between an unreacted urethane prepolymer and an extender and to crosslink allophanate.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION

(Urethane Prepolymer) As the urethane prepolymer, the same urethane prepolymer as that used in the production of known polyurethane balloons can be used, and this urethane prepolymer usually contains a polyvalent isocyanate compound and a polyol. Is a reaction product of. The polyvalent isocyanate compound is a compound having two or more isocyanate groups. Specific examples thereof include aromatic isocyanates such as diphenylmethane diisocyanate, naphthalene diisocyanate, tolylene diisocyanate, tetramethylxylene diisocyanate and xylene diisocyanate; dicyclohexane diisocyanate, dicyclohexylmethane diisocyanate. Examples thereof include aliphatic isocyanate such as nato, hexamethylene diisocyanate, and isophorone diisocyanate.
Of these polyvalent isocyanate compounds, diphenylmethane diisocyanate is preferable because it is highly safe for living organisms.

The polyol is a compound having two or more hydroxyl groups which undergo a polyaddition reaction with an isocyanate group, and usually has a molecular weight of more than about 500. Specific examples thereof include polyoxytetramethylene glycol and polyethylene glycol. , A polyether polyol such as polypropylene glycol; a dehydration condensation product of a polyvalent carboxylic acid such as adipic acid and a polyhydric alcohol such as glycol or triol; a polyester polyol such as a polycarbonate diol; and a polybutadiene polyol. Of these compounds, polyether polyols, particularly polyoxytetramethylene glycol, are preferable because they have good biocompatibility and are safe for living bodies.

In forming the urethane prepolymer,
It is preferable to heat when or after mixing the polyvalent isocyanate compound and the polyol. The heating temperature is usually 50 to 100 ° C, preferably 60 to 90 ° C. If it is less than 50 ° C, the prepolymer formation reaction takes time, and if it exceeds 100 ° C, the second step operation becomes difficult, and the permanent elongation of the molded article is large and the tensile strength, tear strength and elongation are small. Become. The heating time is usually 10 to 480 minutes, preferably 30 to 120 minutes.

(Extender) An extender is a compound used to extend a polyurethane chain, and is usually
Having two functional groups that undergo a polyaddition reaction with an isocyanate group,
A compound having a molecular weight of 500 or less, preferably 400 or less, and a compound having 3 or more functional groups capable of polyaddition reaction with an isocyanate group and having a molecular weight of 700 or less, preferably 600 or less, are used.

Specific examples of the extender having two functional groups that react with an isocyanate group include ethylene glycol, diethylene glycol, propylene glycol,
Diols such as 1,4-butanediol and 1,6-hexanediol; ethylenediamine, hexamethylenediamine, N, N′-diisopropylmethylenediamine,
Examples thereof include diamines such as N, N'-sec-butyl-p-phenylenediamine. Among these compounds, ethylenediamine and 1,4-butanediol are preferably used because the strength of the molded product is increased by using them.

Specific examples of the extender having three or more functional groups capable of reacting with an isocyanate group include glycerin, trimethylolpropane, pentaerythritol, sorbitol, methyleneglycoside, N-tetrapropynoldiethylamine and sucrose. Trifunctional or higher functional polyols; trifunctional or higher functional polyamines such as 1,3,5-triaminobenzene. Of these compounds, trimethylolpropane and glycerin are preferably used.

It is preferable to use both the bifunctional extender and the trifunctional or higher extender. A combination of extenders particularly suitable for increasing the tear strength and tensile strength of a molded article and decreasing the permanent elongation is ethylenediamine or 1,4-butanediol as the bifunctional extender and the trifunctional extender. This is a combination using trimethylolpropane. The ratio of the bifunctional extender to the trifunctional or higher extender is such that the amount of the functional group which undergoes a polyaddition reaction with the isocyanate group in the bifunctional extender is equal to or greater than that in the bifunctional extender. The amount is usually 70 to 97 mol%, preferably 80 to 95 mol%, based on the total amount of the functional groups that undergo a polyaddition reaction with the isocyanate group in the agent. If it is less than 70 mol%, the elongation and tear strength of the extruded product will be low. On the other hand, when it exceeds 97 mol%, the effect of increasing the tear strength and the tensile strength of the extruded product decreases.

The proportions of the urethane polymer and the extender used are such that excess isocyanate groups will be present when the reaction between the two is complete. Isocyanate group /
The molar ratio of functional groups that react with isocyanate groups must be greater than 1 and less than or equal to 2. The preferable range of the molar ratio is 1.01 to 1.25, and the more preferable range is 1.0.
It is 5 to 1.18. The excess isocyanate groups cause allophanate cross-linking to give the desired tensile properties. If the amount of the extender is too small, the extrudate will have low tensile strength and low elongation. On the contrary, if the amount of the extender is too large, the permanent elongation becomes large.

(Primary heating) A composition containing a urethane prepolymer and an extender is subjected to primary heating to react the urethane polymer with the extender, and then subjected to extrusion molding. The composition before primary heating is generally 1,500 to 5,0.
Although it has a viscosity of 00 cp (measured with a Brookfield viscometer at 23 ° C. under the conditions of 50 RPM and No. 28 spindle), the viscosity of the reaction product by primary heating (using a Brookfield viscometer at the heating temperature described below) 0.4 RPM, value obtained under No. 28 spindle condition) is in the range of 50,000 to 2,000,000 cp, preferably 100,000 to 1,500,000
Set to cp.

The heating temperature is usually 110 to 220 ° C, preferably 130 to 200 ° C, more preferably 165 to 165 ° C.
190 ° C. When the heating temperature is low, the composition does not react and extrusion cannot be performed. If it is too high, a decomposition reaction occurs, and physical properties such as permanent elongation deteriorate. The heating time is usually 1 to 40 minutes, preferably 3 to 30 minutes. If the heating is insufficient, the composition does not reach the desired viscosity and its reaction product can be coated and extruded, but the extrudate is viscous and cannot be wound. vice versa,
If it is overheated, the viscosity becomes high and it becomes difficult to extrude the coating.

If necessary, the composition to be subjected to the primary heating may be a filler such as colloidal silica, white carbon, calcium carbonate; plastic such as dibutyl phthalate, di (2-ethylhexyl) phthalate, di (2-ethylhexyl) adipate. Agents; softening agents such as white oil and paraffin; tertiary amines and alkyl tins that accelerate the reaction of polyvalent isocyanate compounds with polyols and extenders can be added.

The apparatus for performing the primary heating is not particularly limited as long as it produces a reaction product having a desired viscosity. As an example of a typical apparatus, two raw material liquids from a urethane prepolymer storage tank and an extender storage tank are combined and mixed in a mixer, and the mixed liquid is passed through a liquid reservoir to one end of a tubular reactor. The mixed product is heated in the reactor, reacted, discharged from the other end of the reactor through a pump, and the reaction product which has reached the desired viscosity is immediately extruded by a core wire extrusion apparatus or an inside mandrel extruder. An example is an apparatus configured to be transferred to a molding apparatus.

(Extrusion Molding) Extrusion molding of a tube is generally carried out by a core wire coating extrusion method or an inside mandrel extrusion method. The core wire coating extrusion method comprises extracting a core wire from a core wire bobbin, passing the core wire through a mandrel or a crosshead die, and uniformly coating the composition reaction product of the urethane prepolymer on the outer peripheral surface of the core wire, and then cooling the core wire. Become.

As the core wire, a wire made of metal such as stainless steel or copper, or a wire coated with a resin such as fluororesin is used. Alternatively, a resin wire may be used. The surface of the core wire is preferably made of a material having low compatibility with polyurethane in order to facilitate mold release. The outer diameter of the core wire is selected to match the outer diameter of the catheter tube to which the balloon tube is attached. The coating film thickness of the reaction product is determined depending on the target wall thickness of the balloon tube, but is usually 0.05 to 2 mm, preferably 0.1 to 0.5 mm. The viscosity of the reaction product is 1
If it is less than 0,000 cp, after coating extrusion, 1
When heated to 50 to 200 ° C, the viscosity becomes 100,
Adjust to 000-2,000,000 cp.

The viscosity is 100,000 to 2,000,000.
It is preferable to cool after adjusting to 0 cp. When cooled, the reaction product coated with the core wire is likely to be restored even when it is deformed during winding. The cooling temperature is 0 to 100 ° C, preferably 0 to 30 ° C. The cooling means is not particularly limited,
Usually, a method of blowing cold air is adopted. The Shore A hardness of the reaction product after cooling is usually 20 to 90 degrees. The winding speed of the core wire on which the reaction product coating is formed is usually 0.5 to 10 m / min and 2 to 5 m / min.

The core wire coated with the reaction product is cut into a desired length and heated at 100 to 130 ° C. for 1 to 24 hours to complete the reaction between the unreacted urethane prepolymer and the extender. , Crosslink the reaction product with allophanate. This heating is preferably performed in a constant temperature bath.

The coated core wire cut into a desired length is immersed in a solvent to swell the reaction product, and then the core wire is extracted to obtain a tubular reaction product. Inside mandrel extrusion molding can be performed instead of the core wire coating extrusion. That is, the reaction product discharged from the reactor can be extruded through the annular slit between the outer die and the inside mandrel to directly obtain the tubular reaction product.

The outside diameter of the inside mandrel is selected to match the outside diameter of the catheter tube to which the balloon tube is attached. It is desirable to circulate cooling water inside the inside mandrel, and to cool the tubular reaction product leaving the inside mandrel by blowing cooling air from a donut-shaped cooling ring over the entire outer periphery thereof. The cooled tubular reaction product is cut into a desired length as in the case of core wire coating extrusion, and further,
Secondary heating completes the reaction between the unreacted urethane prepolymer and the extender and at the same time crosslinks the reaction product with allophanate.

(Attachment to Catheter) The tubular reaction product extruded as described above is attached to a catheter as a balloon tube. FIG. 1 shows a state in which a balloon tube 2 (2 ′) is attached near the tip of the catheter 1. For convenience, FIG.
Both the closed state of the balloon tube 2 and the inflated state of the balloon tube 2'are shown. The balloon tube 2 (2 ') is attached to the catheter 1 by adhesion (4a, 4b) or fusion. The balloon tube is inflated by sending air or physiological saline through the balloon lumen 3 of the catheter 1, and is deflated by discharging air or physiological saline to return to the state before expansion.

(Examples) The present invention will be specifically described below with reference to examples. In the examples and comparative examples, the characteristics of the tubes were evaluated by the following methods. (1) Extrudability The molded tube was not deformed when it was secondarily heated and passed (A), and the deformed tube was rejected (B).

(2) Tensile properties A sheet having a thickness of 2 mm was formed into a No. 3 type dumbbell (JIS K630).
It was punched out according to 1), and this was compliant with JIS K6301.
The elongation between breaks (%) and the tensile strength (kg / cm ² ) were determined under conditions of a chuck distance of 20 mm, a pulling speed of 500 mm / min, a temperature of 23 ° C. and a relative humidity of 65%.
The permanent elongation was measured as follows. 2mm thick sheet 3
It was punched out with a No. Dumbbell (JISK6301) and marked on its surface at 2 cm intervals in the tensile direction. Distance between chucks 20 mm, pulling speed 500 mm / min, temperature 2
Under the conditions of 3 ° C. and 65% relative humidity, the sample was pulled until the elongation reached 500%, and that state was maintained for 10 minutes. After elimination of force, 1
The sample was allowed to stand for 0 minute and the interval between the marked lines was measured. The difference between the marked line intervals before and after the pulling was determined by the ratio (%) to the marked line interval before the pulling (2 cm), and this was taken as the permanent elongation. Elongation is 60
0% or more, tensile strength 15 MPa or more, permanent elongation 20
% Or less is considered to be at a sufficiently satisfactory level.

(3) Appearance A tube having a smooth appearance was judged to be acceptable (A), and one having a rough surface was judged to be unacceptable (B). (4) Uneven wall thickness The tube was cut, and the maximum value a and the minimum value b of the tube wall thickness were measured on the cut surface. The thickness deviation rate is calculated by the following formula, and if the thickness deviation rate is 10% or more, it is regarded as rejected (B) and 1
Those with less than 0% were regarded as passing (A). Unevenness rate (%) = [(a-b) / a] x 100

Example 1 100 mol of diphenylmethane diisocyanate (MDI) and polyoxytetramethylene glycol having a number average molecular weight of 1,000 (PTMG: SN-10 manufactured by Hodogaya Chemical Co., Ltd.)
00) and 50 mol were mixed and stirred at 80 ° C. for 1 hour to obtain a urethane prepolymer. On the other hand, 35 mol of PTMG,
7 mol of 1,4-butanediol (1,4-BD) and 2 mol of trimethylolpropane (TMP) were mixed to obtain an extender.

The above-mentioned urethane prepolymer and the extender were poured into a liquid mixer (MPG-XO20: Japan Laborsaving Research Institute) and mixed. The viscosity of the mixed solution is about 3,000 at room temperature.
cp. This mixed solution has a total length of 1.8 m and an inner diameter of 2 mm.
Was passed through the stainless steel tubular reactor (tube reactor) at a temperature of 180 ° C. for a retention time of 10 minutes. Viscosity at reactor discharge (0.4 RPM, No. 28
Spindle, Brookfield viscosity) was 600,000 cp at 180 ° C.

Then, a 0.2 mm thick coat was formed on a core wire made of tetrafluoroethylene perfluoroalkyl vinyl ether copolymer (PFA) having an outer diameter of 1.8 mm through a wire coat mandrel. The moving speed of the core wire was 800 mm / min. The coated product is cooled with a cooler (air cooling type), cut into a length of 100 mm, and placed in a constant temperature bath.
Allophanate was crosslinked by standing at 0 ° C. for 24 hours. Then, the coated product was swollen by immersing it in an aqueous ethanol solution having a concentration of 70% by weight for 1 hour, and then demolded. The demolded coated product (tube) was vacuum dried. The raw material composition and manufacturing conditions are shown in Table 1, and the extrusion moldability and the physical properties of the resulting tube are shown in Table 2.

Examples 2 to 4 Tubes were manufactured in the same manner as in Example 1 except that the raw material composition was changed as shown in Table 1. Table 2 shows the evaluation results.
In Example 2, 4,4′-dicyclohexylmethane diisocyanate (H-MDI) was used as the polyvalent isocyanate compound, poly-3-methyloxytetramethylene glycol (3Me-PTMG) was used as the polyol,
3Me-PTMG, ethylenediamine (EDA) and glycerin were used as extenders.

Comparative Example 1 A urethane prepolymer and an extender were prepared in the same manner as in Example 1, and a mixed solution of both was prepared. Without heating the obtained polymer raw material mixed solution (that is, without passing through the tubular reactor as in Example 1).
A 0.2 mm-thick coat was formed on a wire having a diameter of 1.80 mm, reacted in dry air at 110 ° C. for 24 hours, demolded and dried in the same manner as in Example 1 to obtain a tube. This tube was completely unsatisfactory as a balloon because the unreacted mixture fluidized during heating.

Comparative Example 2 As in Example 1, a urethane polymer and an extender were reacted at 180 ° C. for 10 minutes to give a viscosity of 600,000 c.
A reaction product of p (180 ° C.) was obtained. This reaction product was extruded from a pelletizer with a diameter of 2 mm and the average length was 4 mm.
It was cut into pieces, air-cooled for 20 minutes, and further powdered to prevent sticking. When this powdering was omitted, the pellets adhered and caused blocking. 180 ° C
In order to cool the reaction product of (1), water cooling is more effective in cooling instead of the above air cooling, but a pellet drying step is required, which causes a change in the physical properties of the polymer. Using the above powdered pellets, extrusion molding was performed through a uniaxial extruder equipped with a wire coating mandrel at the tip, and the same process as in Example 1 was carried out to obtain a balloon tube. The raw material composition and the production conditions of the reaction product are shown in Table 1, and the extrudability and physical properties of the tube are shown in Table 2.

[0034]

[Table 1]

[0035]

[Table 2]

As shown in Table 2, even if a composition comprising a urethane prepolymer and an extender is extruded without heat reaction, a tube having a stable form cannot be obtained at all (Comparative Example 1). Further, even if a composition containing a urethane prepolymer and an extender is heated and reacted to obtain a reaction mixture having a desired viscosity, when the mixture is pelletized and then extrusion-molded, both the tensile properties of the tube and the wall thickness deviation are obtained. Inferior (Comparative Example 2). ADVANTAGE OF THE INVENTION According to this invention, the extrusion moldability is favorable and it has the tensile strength suitable for a balloon, elongation, and permanent elongation, and a highly accurate tube is obtained (Examples 1-4).

[0037]

According to the present invention, a composition comprising a urethane prepolymer and an extender is reacted by heating and extruded immediately when a predetermined viscosity is reached, followed by secondary heating, which results in good extrusion moldability. Thus, it is possible to industrially manufacture a thin balloon tube having a tensile strength, an elongation and a permanent elongation suitable for a balloon and having a high thickness accuracy.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a state in which a balloon tube of the present invention is attached to a tube tip of a catheter. 1: Catheter 2, 2 ': Balloon tube 3: Balloon lumen 4a, 4b: Balloon tube adhesive part

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location // B29K 75:00 B29L 23:00

Claims (1)

[Claims] 1. A urethane prepolymer containing a urethane prepolymer and an extender and having a molar ratio of isocyanate group / functional group reacting with an isocyanate group of more than 1 and 2 or less is heated to prepare a urethane prepolymer. Reacting the polymer with the extender,
The viscosity of the reaction product is 50,000 to 2,000,000.
A balloon characterized by being extruded immediately after reaching a state of 0 cp and then heating the extruded reaction product to complete the reaction between the unreacted urethane prepolymer and the extender and to crosslink allophanate. How to make a tube.