JPH07102170A - Shape memory polyurethane composition - Google Patents

Abstract

PURPOSE:To obtain a shape memory polyurethane composition capable of giving molded forms retaining their shape memory nature even if subjected to ultraviolet irradiation, useful for sportswear, by incorporating a shape memory polyurethane with an antioxidant. CONSTITUTION:The objective composition can be obtained by incorporating (A) a shape memory polyurethane with (B) pref. 0.1-20wt.%, based on the component A, of an antioxidant (pref. 2,4dihydroxybenzophenone).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shape memory polyurethane composition, and more particularly to a shape memory polyurethane composition capable of giving a molded product whose shape memory property is not deteriorated by ultraviolet rays.

[0002]

2. Description of the Related Art A polyurethane elastomer molded body made of shape memory polyurethane is molded into a shape required for actual use, and then deformed at a temperature not lower than the glass transition temperature of the polyurethane elastomer but lower than the molding temperature. After that, when the deformation is cooled and solidified below the glass transition point temperature and heated again to a temperature above the glass transition point temperature, the deformation can be automatically removed and the original shape of the glass can be recovered, and the glass Various physical properties such as electric conductivity, dielectric constant, refractive index, and water permeability change greatly at the transition temperature, and it is possible to use the deformed shape and the original molded shape or various physical properties by temperature operation. it can. The polyurethane molded article is used in various fields including medical treatment and industry by utilizing such shape memory property.

[0003]

However, recent studies by the present inventors have revealed that the shape memory polyurethane currently used loses its shape memory property in an extremely short time due to ultraviolet rays. did.

Therefore, an object of the present invention is to provide a shape-memory polyurethane composition capable of giving a molded product which does not lose its shape-memory property even when it is irradiated with ultraviolet rays, and the object of the present invention is novel. It is a thing.

[0005]

That is, the present invention relates to a shape memory polyurethane composition comprising a shape memory polyurethane and an antioxidant.

Shape memory polyurethane is a typical synthesis method in which an isocyanate, a polyol and a chain extender are synthesized by a prepolymer method. The glass transition temperature (Tg) of the shape memory polyurethane can be freely selected depending on the combination of the hard segment (isocyanate, chain extender) and the soft segment (polyol). For example, when Tg is set near the human body temperature, shape memory properties are exhibited in that temperature region, and various physical properties change suddenly.

Factors affecting Tg and physical properties are 1) type of isocyanate, 2) type of polyol, 3) type of chain extender, 4) blending ratio of isocyanate and polyol, 5) chain extender and urethane prepolymer. Compounding ratio of
6) Annealing or the like is conceivable, but by changing these factors, it is possible to freely synthesize a shape memory polyurethane having desired Tg and physical properties.

As the isocyanate component, which is the raw material of the shape-memory polyurethane used in the present invention, those which are usually used in polyurethane can be used without particular limitation. For example, diphenylmethane diisocyanate, 2,
Examples thereof include bifunctional isocyanates such as 4- or 2,6-tolylene diisocyanate, m- or p-phenylene diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate.

As the polyol component, one having at least two hydroxyl groups in one molecule is used. For example, polyoxyalkylene polyols produced by adding alkylene oxides to polyhydric alcohols such as diols (polyethylene glycol, polypropylene glycol, etc.) and triols, aliphatic amines and aromatic amines as initiators, acids and alcohols. Examples thereof include polyester polyols (1,4-butane glycol adipate, etc.) produced by condensation of, polytetramethylene glycol, polybutadiene polyol, a mixture of bisphenol A and propylene oxide, and the like.

As the chain extender, ethylene glycol,
Butanediol, glycols such as diethylene glycol, amines such as diethanolamine, triethanolamine, tolylenediamine and hexamethylenediamine,
Examples thereof include trimethylolpropane TDI (tolylene diisocyanate) adducts and polyisocyanates such as triphenylmethane triisocyanate.

A catalyst is also used to accelerate the reaction if necessary. Typical examples of the catalyst include tertiary amines such as triethylamine, tetramethylpropylenediamine, tetramethylhexamethylenediamine and tolylenediamine, and tin-based catalysts such as stannas octoate, stannas oleate and dibutyltin dilaurate. A metal catalyst etc. are mentioned.

In the method of synthesizing the shape memory polyurethane by the prepolymer method, first, the isocyanate and the polyol are reacted at a specific compounding ratio (molar ratio) depending on the Tg for setting the polyol to synthesize the polyurethane prepolymer. After the completion of the reaction, the chain extender is added so that the blending ratio (molar ratio) of the prepolymer and the chain extender is set to a desired blending ratio to obtain a shape memory polyurethane.

For example, Tg is set to a value near the human body temperature (36 to 3).
In the case of producing a shape memory polyurethane set to 7 ° C.), the isocyanate component, the chain extender, and the polyol component are mixed in a ratio of 1.9 to 2.2: 0.9 to 1.2: 1 (molar ratio). Then, the reaction is carried out with or without a catalyst.

As the anti-aging agent added to the shape memory polyurethane, an ultraviolet deterioration preventing agent, an antioxidant, a processing deterioration preventing agent, a metal damage preventing agent and the like are added. 2,4-dihydroxybenzophenone, 2 as an ultraviolet deterioration inhibitor
-Hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone and other benzophenone-based UV deterioration inhibitors, phenyl salicylate, 4-
Salicylate-based UV deterioration inhibitor such as t-butylphenyl salicylate, 2- (2′-hydroxy-3 ′, 5 ′)
-Di-t-butylphenyl) -benzotriazole, 2
-(2'-hydroxy-3'-t-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2-
Examples thereof include benzotriazole-based UV deterioration inhibitors such as (2′-hydroxy-3,5′-di-t-amylphenyl) -benzotriazole. As an antioxidant,
Tetrakis (methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate) methane,
2,5-di-t-amylhydroquinone, 2,5-di-
t-Butyl hydroquinone, 2,2-methylene-bis-
(6-t-butyl-4-methylphenol) and other phenolic antioxidants, 4,4- (α, α-dimethylbenzyl) diphenylamine, N-phenyl-N-isopropyl-p-phenylenediamine, poly (2 , 2,4-Trimethyl-1,2-dihydroquinoline) and other amine-based antioxidants, pentaerythritol tetrakis (β-lauryl thiopropionate), 2,2-thio [diethyl-bis-3 (3,5 -Di-t-butyl-4-hydroxyphenol)] propionate and other sulfur-based antioxidants.

The amount of the antioxidant added is about 0.1 to 20% by weight, preferably 0.5 to 10% by weight, more preferably 1 to 5% by weight, based on the shape memory polyurethane. If the addition amount is less than 0.1% by weight, the deterioration property against ultraviolet rays cannot be improved, while if it exceeds 20% by weight, not only the occurrence of bleeding and the deterioration of physical properties but also the shape memory property is deteriorated. I will let you.

The shape memory polyurethane composition of the present invention thus obtained has a Tg of the shape memory polyurethane.
To give deformation at temperatures below the molding temperature. There is no particular limitation on how to apply the deformation, and the molded product can be placed in an atmosphere having a temperature of Tg or higher (for example, in heated air, heated liquid, steam, etc.) and deformed with an appropriate tool or bare hands. To fix the deformation, it suffices to cool it to a temperature of Tg or less immediately after the deformation is applied, but creep deformation can be applied at Tg or less. In order to remove the deformation from the molded product obtained from the composition of the present invention and change it into a predetermined shape or physical properties, it is preferable to heat the molded product to a temperature of Tg or higher and lower than the molding temperature, and the deformation is automatically removed. The shape is recovered and the physical properties are changed.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to the following examples.

Example 1 Shape memory polyurethane (TPU) having a glass transition temperature (Tg) of about 45 ° C. (trade name: MM4510, manufactured by Mitsubishi Heavy Industries) and 2,4-dihydroxybenzophenone as an anti-aging agent in TPU. Then, 2% by weight was added, and the mixture was kneaded with a biaxial kneader and then press-molded at 190 ° C. to obtain a dumbbell test piece (length, 100 mm) having a thickness of 1 mm. The obtained test piece was irradiated with a weather meter, and the change in shape memory property at the temperature (60 ° C.) of Tg or higher of the dumbbell test piece with respect to the irradiation time was measured as follows. Tensile deformation (50 m) on dumbbell test pieces at a temperature above the shape memory Tg
m) and then cooled below Tg while maintaining the deformation. Then, the amount of deformation recovery (Lmm) when heated again to 60 ° C. is measured. Shape memory property = L / 50 × 100 The results are shown in Table 1.

Examples 2 to 6 A shape memory polyurethane test piece was prepared in the same procedure as in Example 1 except that the kind or blending amount of the antioxidant was changed as shown in Table 1. The shape memory property was measured. The results are shown in Table 1.

Comparative Example 1 A dumbbell test piece was prepared in the same procedure as in Example 1 except that the antiaging agent was not used, and its shape memory property was measured. The results are shown in Table 1.

[0021]

[Table 1]

[0022]

EFFECTS OF THE INVENTION Shape memory polyurethane is widely used in various fields due to its characteristics, but the present invention further expands the field of application. That is, it can be widely used for applications in which shape changes and physical property changes due to temperature changes are used. In particular, by appropriately setting the glass transition temperature, various physical properties such as shape, electric conductivity, dielectric constant, refractive index, and water permeability, especially water absorption, can be significantly changed depending on external temperature such as body temperature. Therefore, it is suitably used for products used outdoors such as sportswear.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takahiko Hirata 3-4-1 Marunouchi, Chiyoda-ku, Tokyo (New International Building) Inside the Tokyo office of Mitsubishi Cable Industries, Ltd. (72) Inventor Motohiko Yamazaki Higashi Amagasaki, Hyogo Prefecture 8 Mukojima Nishinomachi Mitsubishi Electric Wire & Cable Co., Ltd. (72) Inventor Kenjiro Ishihara 7-1526 Fukushima, Fukushima-ku, Osaka (Osaka YM Building) Mitsubishi Cable Industries, Ltd. Osaka Office (72) Inventor Kaiho Hyogo Pref., Nishinomachi, Higashimukaijima, Amagasaki city

Claims (2)

[Claims] 1. A shape memory polyurethane composition comprising a shape memory polyurethane and an antioxidant. 2. The composition according to claim 1, wherein the antiaging agent is 0.1 to 20% by weight based on the shape memory polyurethane.