JPH09235366A - Crosslinked polymer and medical sheet comprising the polymer - Google Patents

Abstract

(57) Abstract: A crosslinked polymer having appropriate viscoelasticity during melting and solidification, which is useful as a material for a radiotherapy sheet, a cast sheet, a wig or a tooth shaping sheet, etc. provide. A cross-linked polymer obtained by irradiating a thermoplastic resin having a melting point of 40 to 80 ° C. with an active energy ray to cause a cross-linking reaction, and a medical use comprising the cross-linked polymer. Sheet.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a crosslinked polymer by irradiation with active energy rays and a medical sheet comprising the crosslinked polymer. More specifically, the present invention relates to a crosslinked polymer having appropriate viscoelasticity at a relatively low temperature by irradiation with active energy rays, and a radiation treatment sheet, a cast sheet and a wig or tooth shaping sheet made of the crosslinked polymer.

[0002]

2. Description of the Related Art Thermoplastic resins such as polycaprolactone and polyisoprene having a melting point (softening point) in the range of 40 to 80 ° C. are easily melted at a relatively low temperature and easily deformed when an external force is applied. It is used for forming sheets such as casts, wigs and teeth by taking advantage of its toughness when cooled and solidified.

[0003]

However, since the viscosity of these resins in the molten state is low and there is no elasticity, "sagging" occurs, breaks when excessive external force is applied, or once deformed. There is a drawback that it does not return to the shape of.

[0004]

DISCLOSURE OF THE INVENTION As a result of investigations, the inventors of the present invention have found that a resin obtained by irradiating a low melting point thermoplastic resin with an active energy ray to cause a crosslinking reaction has a rubber elasticity and a shape memory property in a molten state. Further, it was found that when this resin is used for various medical sheets, the sheet can be freely molded without causing "sagging" or breakage of the sheet, and the present invention has been completed.

That is, the present invention provides a crosslinked polymer which is obtained by irradiating a thermoplastic resin having a melting point of 40 to 80 ° C. with an active energy ray to cause a crosslinking reaction.

The present invention also provides a radiation treatment sheet, a cast sheet and a wig or tooth shaping sheet which are characterized by comprising the above-mentioned cross-linked polymer.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The melting point of the present invention is 40-80.
There is no particular limitation on the thermoplastic resin having a temperature of ℃, polyester resin such as polylactone or copolyester resin, copolyamide resin, polyester polyether, polyester polyamide, polyester elastomer such as polyester polycarbonate, polytransisoprene, polycyclooctene. Polydiene resin such as
Polyolefin resin, ionomer, acrylic resin, thermoplastic polyurethane resin and ethylene copolymer resin such as ethylene-vinyl acetate, ethylene-vinyl chloride, ethylene-vinyl alcohol (saponified ethylene-vinyl acetate copolymer) and ethylene. -Among the propylene-based copolymers, any resin can be used as long as it has a melting point of 40 to 80 ° C. 10-4 copolymer components
The proportion of 0 mol% is usually preferable because the melting point is in the range of 40 to 80 ° C.

Among them, at least one resin selected from the group consisting of polycaprolactone resins, polytransisoprene resins and ethylene copolymer resins is currently manufactured on a commercial scale and can be preferably used. The polycaprolactone resin is a resin obtained by ring-opening polymerization of ε-caprolactone with various alcohols as an initiator, a resin of a copolymer of ε-caprolactone and a monomer other than ε-caprolactone, and these resins. Shows a modified resin or resin mixture of. The ethylene-based copolymer resin has crystallinity, but is excellent in transparency, and is preferably used in the case where the transparency is required in a shaping sheet such as a wig shaping material.

Of these, polycaprolactone resins having a radical-polymerizable double bond or a benzyl group in the molecule are more preferable. As a method of synthesizing these,
Start 2-hydroxyethyl methacrylate, allyl alcohol, tetrahydrobenzyl alcohol, ethylene oxide modified bis (4-hydroxyphenyl) ethane or ethylene oxide modified 2,2'-bis (3,5-dimethyl-4-hydroxyphenyl) propane Used as an agent, ring-opening polymerization of ε-caprolactone, a method of coupling with a polyfunctional isocyanate or the like in some cases, ethylene glycol trimethylolpropane, pentaerythritol and the like as an initiator ε-caprolactone ring-opening polymerization, Examples thereof include a method of esterifying the terminal hydroxyl group with maleic anhydride, tetrahydrophthalic anhydride, methylbenzoic acid and the like.

The number average molecular weight of the thermoplastic resin having a melting point of 40 to 80 ° C. is usually 10,000 to 300,
000, preferably 40,000 to 200,000, more preferably 60,000 to 150,000. When the molecular weight is less than 10,000, it is difficult to produce various molded products, and the mechanical strength of the produced product tends to be remarkably low, and conversely 300,00.
If it exceeds 0, the melt viscosity tends to be too high, and the moldability tends to decrease, such being undesirable.

The reason why the melting point is 40 to 80 ° C. is that a cross-linked polymer obtained from one having a melting point of less than 40 ° C. is difficult to store in the summer or when used as a fixing sheet, even at room temperature. Since it does not solidify easily, it may be difficult to use. Conversely, in the case of a cross-linked polymer obtained from a polymer having a temperature higher than 80 ° C, the molten resin is hot.
It is not suitable because it cannot be placed on the human body.

In a preferred embodiment of the present invention, the melting point is 40 to
A polyfunctional acrylic monomer and a polyfunctional allyl monomer are added to a thermoplastic resin at 80 ° C. These monomers are not particularly limited, and examples of polyfunctional acrylic monomers include ethylene oxide-modified bisphenol A di (meth) acrylate and 1,4-butanediol di (meth).
Acrylate, diethylene glycol di (meth) acrylate, dipentaerythritol hexaacrylate,
Dipentaerythritol monohydroxypentaacrylate, caprolactone modified dipentaerythritol hexaacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, polyethylene glycol di (meth) acrylate, trimethylolpropane triacrylate, ethylene oxide modified trimethylolpropane triacrylate, propylene Oxide-modified trimethylolpropane triacrylate, tris (acryloxyethyl) isocyanurate, tris (methacryloxyethyl) isocyanurate, and mixtures thereof are examples of polyfunctional allyl monomers, triallyl cyanurate, triallyl. Isocyanurate diallyl phthalate, diallyl benzene phosphonate and this Include mixtures of.

These polyfunctional acrylic monomers or polyfunctional allyl monomers are added to 100 parts by weight of at least one resin selected from the group of polycaprolactone resins, polytransisoprene resins and ethylene copolymer resins. On the other hand, 0.1 to 30 parts by weight, preferably 0.3 to 10 parts by weight, and more preferably 0.5 to 5 parts by weight are mixed. If the amount is less than 0.1 part by weight, the shape memory property of the crosslinked polymer is not at a satisfactory level, and conversely 30
If the amount is more than parts by weight, the crosslinked polymer becomes too rigid and the toughness tends to decrease, which is not preferable.

As the active energy ray, its wavelength and
The amount of energy is not particularly limited, but an electron beam (EB) is common. These active energy rays can be irradiated using a known device. The irradiation dose is appropriately selected so that the thermoplastic resin can be crosslinked. For example,
The acceleration voltage in the case of electron beam (EB) is 100 to 30.
The range of 0 KV and the absorbed dose is preferably 0.1 to 30 Mrad.

When irradiating with these active energy rays, the form of the thermoplastic resin having a melting point of 40 to 80 ° C. is not particularly limited, but a film or sheet having a thickness of 10 μm to 5 mm has an irradiation efficiency. It is easy to use due to its high price. In particular, a sheet having a thickness of about 0.5 mm to 3 mm is preferably used because it can be used as a medical sheet such as a radiation treatment sheet, a cast sheet, a wig or a tooth shaping sheet.

Any substance may be mixed or applied to the crosslinked polymer of the present invention at an appropriate time depending on the intended use.

Examples of the above substances include inorganic fillers such as glass fiber, glass beads, metal powder, talc, mica, silica, pigments, various stabilizers, flame retardants, antistatic agents, antifungal agents, plasticizers, and viscosity imparters. Examples include additives such as agents, thermoplastic resins, curable oligomers, and the like.

The restoration rate of the crosslinked polymer obtained as described above is usually 80% or more.

[0019]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

[Production Example 1] In a 20 liter reactor equipped with a stirrer, a condenser and a temperature controller, 13.4 g (0.1 mo) of trimethylolpropane was used as an initiator.
l), 13.68 kg (epsilon) -caprolactone (120 mo
l) and monobutyltin tris (2-
0.7 g of ethyl hexanate) was charged, and the mixture was stirred at 180 ° C. for 8 hours while flowing a small amount of nitrogen.

At this point, the amount of ε-caprolactone remaining in the system was 0.2%. The temperature of the system was cooled to 120 ° C., 29.4 g (0.3 mol) of maleic anhydride was charged, and the mixture was stirred at 120 ° C. for 2 hours to carry out esterification by the reaction between the terminal hydroxyl group of polycaprolactone and maleic anhydride. It was After that, the stirring was stopped and 2 kg /
A pressure of cm ² was applied to draw a strand of polycaprolactone resin from the lower hole, and the strand was cooled in a water tank and cut using a pelletizer. The resulting pellets were vacuum dried at 40 ° C and used in the examples.

The standard polystyrene equivalent number average molecular weight of this product in GPC measurement was 137,000 and the acid value was 1.4 KOHmg / g.

Examples 1 and 2 Using the polycaprolactone-based resin having a double bond in the molecule obtained in Production Example 1, a 20 cm × 30 cm × 2 mm sheet was prepared by press molding. This sheet was subjected to electron beam (EB) irradiation under two conditions. One is double-sided irradiation with an acceleration voltage of 200 kV and an absorbed dose of 5 Mrad (Example 1), and the other is single-sided irradiation with an acceleration voltage of 5,000 kV and an absorbed dose of 5 Mrad (Example 2). Tensile tests of these sheets at 23 ° C. and 60 ° C. were carried out, and the uniformity and the duplex ratio of the sheets were evaluated. Table 1 shows the results.
Shown in In addition, the measuring method of each physical property is as follows.

1. Breaking strength, strength at 500% elongation and breaking elongation: According to JIS K7113. The tensile strength is measured at 23 ° C, and the rubber strength at the time of melting is measured at 60 ° C. 2. Sheet uniformity: By visual evaluation. 3. Recovery rate: A 10 cm x 1 cm x 2 mm strip-shaped sheet is dipped in a hot water bath at 80 ° C, stretched to 20 cm, and once cooled and solidified. It is dipped again in a hot water bath at 80 ° C. and contracted, and the restoration rate is calculated. 4. Sheet transparency: A sheet having a thickness of 2 mm was visually evaluated. ◯: Completely transparent, Δ: Slightly cloudy, ×: Ground glass-like cloudy.

[Comparative Example 1] For comparison, the electron beam (EB) of the polycaprolactone-based resin sheet obtained in Production Example 1 was used.
The same evaluation as in Example 1 was carried out for those that were not irradiated at all, and the results are also shown in Table 1.

[Examples 3 and 4] 1 part by weight of trimethylolpropane ethylene oxide added triacrylate (TMPEOTA manufactured by Daicel-UCB) was added to 100 parts by weight of the polycaprolactone resin obtained in Production Example 1 (Examples). 3) and 3 parts by weight (Example 4) were added and melt-kneaded at 120 ° C. for 2 minutes using a Labo Plastomill mixer manufactured by Toyo Seiki Co., Ltd., respectively.

A sheet of 20 cm × 20 cm × 2 mm was produced by press molding using the obtained mixed resin. Acceleration voltage 200kV, absorbed dose 5Mra on these sheets
Both sides of the sheet were irradiated with an electron beam (EB) under the condition of d. The same evaluations as in Example 1 were performed on these sheets. The results are shown in Table 1.

[Examples 5 and 6] Polytransisoprene resin sheet (30 cm × 20 cm) obtained on the market
× 3 mm) was finely cut. This was remade into a sheet of 20 cm × 20 cm × 2 mm by press molding.

Separately, with respect to 100 parts by weight of this resin, trimethylolpropane ethylene oxide-added triacrylate (TMPEOTA manufactured by Daicel-UCB) is used.
Was added at a ratio of 1 part by weight, and a mixed resin melt-kneaded at 120 ° C. for 2 minutes using a Labo Plastomill mixer manufactured by Toyo Seiki Co., Ltd. was used to press-mold 20 cm × 20 cm × 2 m.
m sheets were produced.

An electron beam (E) was applied to both sides of these sheets under the conditions of an acceleration voltage of 200 kV and an absorbed dose of 5 Mrad.
B) Irradiation was performed. About the obtained sheet, Example 1
The same evaluation was performed. The results are shown in Table 1.

Comparative Example 2 For comparison, the same polytransisoprene resin sheet (20 cm × 20) as in Example 5 was used.
The same evaluation as in Example 1 was performed for the case where the electron beam (EB) irradiation of (cm × 2 mm) was not performed at all. The results are shown in Table 1.

(Note 1) [Examples 7 to 15 and Comparative Example 3]
And 4] Resins shown in Table 2 and tris (acryloxyethyl) isocyanurate (TA as a polyfunctional acrylic monomer)
EIC) was used to prepare a sheet in the same manner as in Example 1.
The obtained sheet was irradiated with an electron beam at an acceleration voltage of 5,000 kV. (Comparative Examples 3 and 4 were not irradiated with an electron beam.) The obtained sheets were measured for sheet uniformity, sheet transparency, restoration rate and strength at 500% elongation at 75 ° C, and the results are shown in Table- Shown in 2.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

EFFECTS OF THE INVENTION The crosslinked polymer of the present invention melts at a relatively low temperature, and has appropriate viscoelastic properties when melted and when solidified. Therefore, a radiation treatment sheet, a cast sheet and a wig or a tooth are provided. It is useful as a material such as a sheet for molding.

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Claims (7)

[Claims] 1. A cross-linked polymer obtained by irradiating a thermoplastic resin having a melting point of 40 to 80 ° C. with an active energy ray to cause a cross-linking reaction. 2. The resin constituting the thermoplastic resin is at least one selected from the group consisting of polycaprolactone resins, polytransisoprene resins and ethylene copolymer resins.
The crosslinked polymer according to claim 1, which is a kind of resin. 3. A resin 10 comprising a thermoplastic resin.
The crosslinked polymer according to claim 2, which is a resin in which 0 part by weight, 0.1 to 30 parts by weight of a polyfunctional acrylic monomer or a polyfunctional allyl monomer is mixed. 4. The crosslinked polymer according to claim 2, wherein the polycaprolactone-based resin contains a polycaprolactone-based resin having a radical-polymerizable double bond or a benzyl group in the molecule. 5. A radiation treatment sheet comprising the crosslinked polymer according to claim 1. 6. A cast sheet comprising the crosslinked polymer according to any one of claims 1 to 4. 7. A sheet for shaping a wig or a tooth, which is made of the crosslinked polymer according to any one of claims 1 to 4.