JP2744760B2 - Hydrophilic film and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a hydrophilic film having excellent mechanical properties, stability under high humidity and excellent water resistance, comprising a resin having a specific molecular weight comprising polydioxolane. The present invention relates to the manufacturing method.

[0002]

2. Description of the Related Art Polydioxolane is a crystalline hydrophilic polymer synthesized by dehydration condensation of ethylene glycol and paraformaldehyde and ring-opening polymerization of 1,3-dioxolane. In order to obtain a film having excellent physical properties from this polydioxolane, it is essential to optimize the film forming conditions and control the crystallinity, spherulite size and the like.

Meanwhile, polyethylene oxide is a water-soluble crystalline polymer having a structure similar to that of polydioxolane, and its film and production method are known. Both are apt to be regarded as polymers having very similar properties due to their similarity in structure, but the crystallization temperature and crystallization rate are significantly different, and the polyethylene oxide film forming method was used as it was or with some changes in conditions. By itself, it is not possible to obtain a film having excellent physical properties even if it is applied to polydioxolan film formation. For this reason, a film having excellent mechanical properties made of a resin containing polydioxola has not been obtained.

On the other hand, examples of hydrophilic polymers include polyethylene oxide and polyvinyl alcohol.
Films made of these resins have a problem in stability under high humidity. That is, problems such as deterioration of mechanical properties due to moisture absorption, deterioration of handleability due to curling of the film, and development of tackiness on the film surface occur. In addition, most of films made of these resins are water-soluble, and when they come into contact with water, a problem arises in that a part of the film swells or holes are formed. For this reason, when transporting and storing the film, it is necessary to take extra care such as applying special packaging to avoid contact with water. Except when the film is used as a water-soluble film, great care must be taken during use to avoid contact with water.

[0005]

DISCLOSURE OF THE INVENTION In view of the above-mentioned situation, the present inventors have developed a novel resin which has excellent mechanical properties consisting of a resin containing polydioxolane, is stable under high humidity, and has high water resistance. As a result of intensive studies to provide a novel hydrophilic film and a method for producing the same, the present invention has been completed.

[0006]

That is, the present invention comprises a resin comprising polydioxolane and having a number average molecular weight in terms of polystyrene of 50,000 to 500,000 as measured by size exclusion chromatography, The degree of crystallinity measured by wide-angle X-ray diffraction is 25 to 75%, and the spherulite size measured by a polarizing microscope is 50%.
It is intended to provide a hydrophilic film having a thickness of 0 μm or less.

Further, the present invention relates to a resin comprising polydioxolane and having a number average molecular weight in terms of polystyrene of 5 as measured by size exclusion chromatography.
Resin with a molding machine outlet temperature of 50 ° C. to 2
Extruded at 00 ° C. and then the resulting film was
The present invention provides a method for producing a hydrophilic film, characterized in that the film is cooled to -10C to 30C in a cooling time of one minute.

Examples of the resin containing polydioxolan used in the present invention include homopolymers of polydioxolan, and copolymers of 1,3-dioxolan and 1,3-dioxolan as long as the crystallinity of polydioxolan is not impaired. Examples thereof include a block or random copolymer obtained by copolymerizing a possible monomer and a resin composition in which a homopolymer and / or a copolymer are mixed with another polymer as long as the crystallinity of polydioxolane is not impaired. Examples of monomers copolymerizable with 1,3-dioxolane include unsaturated hydrocarbons such as styrene, (meth) acrylic acid, ethylene, and propylene; cyclic ethers such as trioxane, ethylene oxide, propylene oxide, and tetrahydrofuran; -Butyrolactone, glycolide, lactide, ε-
Lactones such as caprolactone and ε-caprolactam or lactams can be mentioned. Examples of the polymer used as a mixture with the dioxolane homopolymer and copolymer include poly (meth) acrylic acid, poly (meth) acrylate, polyvinyl alcohol, polyethylene, polypropylene, polystyrene, polyethylene glycol, polypropylene glycol, polyacetal,
Polytetramethylene oxide, polyethylene terephthalate, polylactic acid, polyglycolic acid, poly (3-hydroxybutyrate), poly (3-hydroxybutyrate-
3-hydroxyvalerate), poly (ε-caprolactone), poly (ethylene succinate), poly (tetramethylene succinate), starch, chitin, chitosan,
Cellulose, carboxymethylcellulose, cellulose acetate and the like can be mentioned.

The resin containing polydioxolane as described above may be a resin synthesized by any conventionally known synthesis method, but has a number average molecular weight in terms of polystyrene of 50,000 to 50, as measured by size exclusion chromatography.
10,000, preferably 80,000 to 500,000, and more preferably 100,000 to 300,000 are suitably used. If the molecular weight of the resin is lower than this range, the film after cooling is brittle, and a film having excellent physical properties, which is the object of the present invention, cannot be obtained. In addition, polydioxolanes having a high molecular weight in which the resin has a molecular weight exceeding this range have a very high melt viscosity, and have extremely poor fluidity when formed into a film, resulting in markedly reduced workability. Further, when a film is required to have both high mechanical strength and excellent workability, polydioxolane having a molecular weight of 100,000 to 300,000 is suitably used.

The resin containing a polydioxolan having a molecular weight suitably used in the present invention is obtained by cationic polymerization of 1,3-dioxolan alone or a mixture of a monomer copolymerizable with 1,3-dioxolan. However, a heteropolyacid such as phosphotungstic acid, silicotungstic acid, phosphomolybdic acid, boron trifluoride or boron trifluoride is used as an initiator in that polydioxolane having a desired molecular weight can be easily synthesized. Etherate, boron fluoride organic compound complex such as triethyloxonium tetrafluoroborate, triethylaluminum,
It is preferable to use an organic metal compound such as aluminum isopropoxide and titanium isopropoxide.

The film comprising the resin containing polydioxolan of the present invention has a crystallinity of 25 to 75%, preferably 30 to 60% as measured by wide-angle X-ray diffraction, and is observed by a polarizing microscope. The spherulite size must be less than 500 μm, preferably less than 100 μm. When the crystallinity is lower than 25%, a film having a very large elongation can be obtained, but the strength of the film is very low. Conversely, when the crystallinity exceeds 75%, a film having high strength can be obtained, but the elongation of the film becomes extremely small. Furthermore, even when the crystallinity of the film is in the above range, if the spherulite size observed by a polarizing microscope is larger than 500 μm, the film has low surface smoothness and only a film with very small elongation can be obtained. . On the other hand, when the spherulite size is small, a film having high strength and large elongation can be obtained, and the transparency and surface smoothness of the film are improved. For this reason, the spherulite size of the present invention has no particular lower limit, and the smaller the spherulite size, the better. A very small spherulite size that cannot be observed with a polarizing microscope can be suitably used. When a film with high transparency is to be obtained, the spherulite size is preferably 400 nm or less.

The film made of the resin containing the polydioxolane of the present invention has a molding machine outlet temperature of 50 ° C. to 20 ° C.
The film is formed by extruding at 0 ° C, preferably 100 ° C to 150 ° C. When the molding machine outlet temperature is higher than this range, the melt viscosity of the resin is very low, and in the case of molding by inflation, it becomes difficult to continuously remove the film because the resin cannot support its own weight, In the case of molding using a T-die, the width of the molten film after extrusion becomes narrower due to surface tension, and problems such as perforation and film breakage occur. Further, if the resin containing polydioxolan is kept at a temperature higher than 200 ° C. for a long time, the resin may be deteriorated, and it is difficult to maintain the uniformity of the quality of the obtained film. If the outlet temperature of the molding machine is lower than this range, it is difficult to obtain a uniform film because the molten state of the resin is not uniform, and the productivity of the film is too high because the melt viscosity of the resin is too high. May drop significantly.

The melted film extruded under the above conditions is cooled to -10 ° C to 30 ° C, preferably 0 ° C to 25 ° C with a cooling time of 2 seconds to 5 minutes, preferably 5 seconds to 3 minutes. Is formed into a film. Extruded film is -1
If cooled to below 0 ° C within 2 seconds,
The crystallization of the resulting film is incomplete, after which the crystallization proceeds further by returning the film to room temperature. Therefore, in addition to the problem that the quality of the film changes with time, the spherulite size becomes very large due to the slow crystallization at room temperature, and the elongation of the film may be reduced. On the other hand, even when the extruded film is not cooled to 30 ° C. or lower within 5 minutes, the productivity of the film is extremely low and the elongation of the film is reduced due to the large spherulite size.

Further, the temperature at the outlet of the molding machine is 100.degree.
Extruded into a film at 0 ° C. and cooled to 0 ° C. to 15 ° C. with a cooling time of 5 seconds to 3 minutes to have good surface smoothness, transparency, uniformity and mechanical properties A hydrophilic film can be manufactured with high molding efficiency.

The method for forming a film comprising polydioxolane of the present invention is not particularly limited, and any conventionally known film manufacturing method can be applied as long as the film forming conditions of the present invention can be satisfied. .
Specific examples include an inflation method, a T-die method, and a calendering method. A film having a degree of crystallinity of 25% to 45% can be obtained by molding under non-stretching conditions using these molding methods. Further, the degree of crystallinity can be increased to 30% to 75% by hot-stretching or cold-stretching the obtained film uniaxially or biaxially in the same manner as a film made of another resin, and the film is stretched. The elongation decreases, but the strength greatly increases. Further, it is also possible to form a multilayer structure by overlapping with another base material.

The thickness of the film of the present invention is not particularly limited. However, in order to obtain a flexible and tough film, the thickness is preferably from 10 μm to 300 μm. If it is to be used as a film, its thickness should be 20 μm or more and 25
It is preferably 0 μm or less. However, when forming a multilayer, if the required strength can be ensured by the base material to be superposed, there is no problem even if the thickness is smaller than 10 μm.

Further, a film comprising a resin comprising the polydioxolane of the present invention may further comprise various stabilizers,
The molding may be performed in a state where additives such as a nucleating agent and an extender are mixed.

[0018]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples.

Reference Example 1 1,3-dioxolane dried using molecular sieves fired at 500 ° C. in a four-necked flask equipped with a stirrer, a cooler, a thermometer and a nitrogen inlet tube (Wako Pure Chemical Industries, Ltd.) 60.00 g), and the internal temperature was adjusted to 3 ° C. in an ice water bath at 0 ° C. To this, as a polymerization initiator, 1
0.4 m of a 5% by weight solution of phosphotungstic acid in methyl ethyl ketone obtained by drying at 20 ° C. for 20 hours
1 was added with stirring. The polymerization started immediately after the addition of the initiator, and reached an exothermic peak of 50 ° C. in about 6 minutes. 50 ice water baths
The temperature of the reactor was changed to a warm water bath at ℃ ° C., and the polymer was aged for 15 minutes. Then, 5 ml of a 0.1% by weight solution of triethylamine in 1,3-dioxolane was added to stop the reaction.

The obtained polydioxolane had a number average molecular weight in terms of polystyrene of 110,000 as measured by size exclusion chromatography.

Reference Example 2 Polymerization was carried out in the same manner as in Reference Example 1, except that 1,3-dioxolan (manufactured by Osaka Organic Chemical Co., Ltd.) was used and the polymerization initiator solution was changed to 0.6 ml. The polymerization started immediately after the addition of the initiator, and reached an exothermic peak of 55 ° C. in about 6 minutes. Thereafter, aging and neutralization of the initiator were performed in the same manner as in Reference Example 1.

The obtained polydioxolane had a number average molecular weight in terms of polystyrene of 150,000 as measured by size exclusion chromatography.

Reference Example 3 Polymerization was carried out in the same manner as in Reference Example 1 except that the amount of the polymerization initiator used was changed to 0.3 ml. The polymerization started immediately after the addition of the initiator, and reached an exothermic peak of 45 ° C. in about 6 minutes. Thereafter, aging and neutralization of the initiator were performed in the same manner as in Reference Example 1.

The resulting polydioxolane had a number average molecular weight in terms of polystyrene of 230,000 as measured by size exclusion chromatography.

Reference Example 4 1,3-dioxolane dried using molecular sieves dried at 500 ° C. and distilled (Osaka Organic Chemical Co., Ltd.)
And the polymerization was carried out in the same manner as in Reference Example 1 except that the amount of the polymerization initiator was changed to 0.3 ml. The polymerization started immediately after the addition of the initiator, and reached an exothermic peak of 60 ° C. in about 3 minutes.
Thereafter, aging and neutralization of the initiator were performed in the same manner as in Reference Example 1.

The obtained polydioxolane had a number average molecular weight in terms of polystyrene of 300,000 as measured by size exclusion chromatography.

Reference Example 5 In a four-necked flask equipped with a stirrer, a cooler, a thermometer and a nitrogen inlet tube, 1,3-dioxolan (Wako Pure Chemical Industries, Ltd.)
60.00 g) and the internal temperature was adjusted to 30 ° C. in a 30 ° C. water bath. In addition, 120 as a polymerization initiator under reduced pressure
0.6 ml of a 5% by weight solution of phosphotungstic acid in methyl ethyl ketone obtained by drying at 20 ° C. for 20 hours was added with stirring. The polymerization started immediately after the addition of the initiator, and reached an exothermic peak of 45 ° C. in about 15 minutes. After replacing the water bath with a warm water bath at 50 ° C. and keeping the reactor warm, the polymer was aged for 15 minutes, and then 0.1% by weight of triethylamine in 1,3
The reaction was stopped by adding 5 ml of dioxolane solution.

The obtained polydioxolane had a number average molecular weight in terms of polystyrene of 40,000 as measured by size exclusion chromatography.

Reference Example 6 1,3-dioxolane dried using molecular sieves dried at 500 ° C. and distilled (Osaka Organic Chemical Co., Ltd.)
And the polymerization was carried out in the same manner as in Reference Example 1 except that the amount of the polymerization initiator was changed to 0.1 ml. The polymerization started immediately after the addition of the initiator, and reached an exothermic peak of 60 ° C. in about 3 minutes.
Thereafter, aging and neutralization of the initiator were performed in the same manner as in Reference Example 1.

The obtained polydioxolane had a number average molecular weight in terms of polystyrene of 550,000 as measured by size exclusion chromatography.

Example 1 Using a CS-194AV Max Mixing Extruder (manufactured by Custom Scientific Instruments), a rotor temperature of 100 ° C. and a shaft rotation speed of 12 were used.
The polydioxolane having a number average molecular weight of 110,000 in terms of polystyrene obtained in Reference Example 1 was extruded under the conditions of 0 rotation / minute, T-die temperature of 115 ° C., and T-die clearance of 0.5 mm. And the film temperature was cooled to 15 ° C. in about 10 seconds to obtain a film of Example 1.

Table 1 shows the thickness, spherulite size, tensile breaking strength in the machine direction and tensile breaking elongation of the obtained film.

The films shown in Table 1 were evaluated as follows.

<Measurement of Crystallinity> The crystallinity was measured using a wide angle X-ray diffractometer RAD-rC system manufactured by Rigaku Corporation.

<Measurement of Spherulite Size> The spherulite size was determined by simply averaging the diameters of 100 spherulites using a polarizing microscope.

<Tensile strength and tensile elongation at break> The tensile strength and tensile elongation at break were measured in accordance with JIS K-7127 using a No. 1 type test piece at a test speed E (20 m / min).
m).

Example 2 Polystyrene-equivalent number average molecular weight of 15 obtained in Reference Example 2
A film of Example 2 was obtained in the same manner as in Example 1 except that the extruded film was stretched 4 times using 10,000 polydioxolanes.

Table 1 shows the thickness, spherulite size, tensile breaking strength in the machine direction, and breaking elongation at break of the obtained film.

Example 3 Polystyrene-equivalent number average molecular weight of 23 obtained in Reference Example 3
A film of Example 3 was obtained in the same manner as in Example 1 except that the extruded film was stretched 4 times using 10,000 polydioxolanes.

Table 1 shows the thickness, spherulite size, tensile strength at break and elongation at break of the obtained film.

Example 4 A film of Example 4 was obtained in the same manner as in Example 2 except that the temperature of the compressed air for cooling was 0 ° C. and the film was cooled to 15 ° C. in about 1 minute.

Table 1 shows the thickness, spherulite size, tensile breaking strength in the machine direction, and tensile breaking elongation of the obtained film.

Example 5 A film of Example 5 was obtained in the same manner as in Example 2 except that the temperature of the compressed air for cooling was 15 ° C. and the film was cooled to 16 ° C. in about 3 minutes.

Table 1 shows the thickness, spherulite size, tensile breaking strength in the machine direction, and tensile breaking elongation of the obtained film.

Example 6 Polystyrene-equivalent number average molecular weight of 30 obtained in Reference Example 4
A film of Example 6 was obtained in the same manner as in Example 1 except that the extruded film was stretched 4 times using 10,000 polydioxolanes.

Table 1 shows the thickness, spherulite size, tensile strength at break and elongation at break of the obtained film.

Comparative Example 1 A film was obtained in the same manner as in Example 1 except that the polydioxolane having a number average molecular weight of 40,000 in terms of polystyrene obtained in Reference Example 5 was used. It could not be stretched twice due to brittleness.
Thus, a film of Comparative Example 1 was obtained without stretching after extrusion.

Table 1 shows the thickness, spherulite size, tensile breaking strength in the machine direction and tensile breaking elongation of the obtained film.

Comparative Example 2 A polystyrene reduced number average molecular weight of 55 obtained in Reference Example 6.
An attempt was made to obtain a film in the same manner as in Example 2 except that 10,000 polydioxolanes were used, but the machine was stopped due to insufficient power of the extruder.

Comparative Example 3 An attempt was made to obtain a film in the same manner as in Example 2 except that the T-die temperature was changed to 45 ° C. However, the molten state of the resin in the T-die became non-uniform, and a uniform film was obtained. I couldn't do that. Further, 5 minutes after the start of the experiment, the machine was stopped due to insufficient power of the extruder.

Comparative Example 4 A film was obtained in the same manner as in Example 2 except that the temperature of the T-die was changed to 220 ° C. However, the melt viscosity of the resin was extremely low, and the resin extruded from the T-die was formed into a thread. It ran off and the film could not be obtained.

Comparative Example 5 The procedure was carried out except that the temperature of the compressed air for cooling was 30.degree. C., the film temperature was cooled to 40.degree. C. over about 7 minutes, and then the compressed air at 0.degree. A film of Comparative Example 5 was obtained in the same manner as in Example 2.

Table 1 shows the thickness, spherulite size, tensile breaking strength in the machine direction, and tensile breaking elongation of the obtained film.

Comparative Example 6 The extruded film was immediately stretched to -20 while being stretched twice.
By contact with a stainless steel drum cooled to
Comparative Example 6 was carried out in the same manner as in Example 2 except that it was cooled to 18 ° C.
Was obtained. While handling the film at room temperature in an attempt to remove the specimen from the resulting film, white spots appeared on the film with new crystallization.

Table 1 shows the thickness, spherulite size, tensile breaking strength in the machine direction and tensile breaking elongation of the obtained film.

[0056]

[Table 1]

[0057]

The film of the present invention comprising a resin comprising polydioxolane has good mechanical properties and surface smoothness. Also, it should be noted that the film of the present invention is extremely excellent in stability under a high humidity environment. That is, while the film of the present invention has high hydrophilicity, the mechanical properties are reduced due to moisture absorption and the film is curled as seen in a film made of another hydrophilic polymer such as polyethylene oxide or polyvinyl alcohol. No problems such as deterioration in handling and adhesion of the surface occur. Furthermore, it should be noted that the film of the present invention also has extremely high water resistance, and even when in direct contact with water, suffers from problems such as swelling and perforation like a film made of polyethylene oxide or polyvinyl alcohol. Not at all. For this reason, unlike the film made of the hydrophilic polymer, the film has an excellent feature that moisture and waterproof measures are not required during transportation and use.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification code FI C08L 71:00 (56) References JP-A-7-41533 (JP, A) JP-A-7-41532 (JP, A) ( 58) Field surveyed (Int. Cl. ⁶ , DB name) C08J 5/18 CEZ C08G 65/06

Claims (4)

(57) [Claims] 1. A crystal comprising a resin comprising polydioxolane and having a number average molecular weight in terms of polystyrene of 50,000 to 500,000 in terms of polystyrene measured by size exclusion chromatography, wherein the crystal is observed by wide-angle X-ray diffraction. A hydrophilic film having a degree of conversion of 25 to 75% and a spherulite size measured by a polarizing microscope of 500 μm or less. 2. The hydrophilic film according to claim 1, wherein the thickness of the obtained film is 10 μm or more and 300 μm or less. 3. A resin comprising polydioxolane and having a polystyrene-equivalent number average molecular weight of 50,000 to 500,000 as measured by size exclusion chromatography, and a molding machine outlet temperature of 50 ° C. to 200 ° C. And extrude the film into a film form for 2 seconds to 5 seconds.
A method for producing a hydrophilic film, comprising cooling to −10 ° C. to 30 ° C. in a cooling time of 1 minute. 4. The method for producing a hydrophilic film according to claim 3, wherein the thickness of the obtained film is 10 μm or more and 300 μm or less.