JPH0243213A - Shape-memory molded article - Google Patents

Abstract

PURPOSE:To obtain a molded article having shape memory characteristics by using a polyurethane resin having a Tg in a specified range, a hardness (Shore D) above a specified value below the Tg and another hardness below a lower specified value at the Tg or higher. CONSTITUTION:A molded article having a shape memory characteristics is obtd. by using a polyurethane resin having a glass transition temp. (hereinbelow described as Tg) in the range of 0-100 deg.C and a hardness (Share D) of 65 or larger below the Tg and a Shore D hardness of smaller than 55 at the Tg or higher. A deformation is given to a molded item constituted of this polyurethane resin at the Tg or higher an this deformation is fixed by cooling it below the Tg of this resin. In using the molded item it is heated at the Tg or higher to reconvert it to its original shape.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides polyurethane 4! The invention relates to a molded body having shape memory properties made of a polyurethane resin, and furthermore, a molded body made of a polyurethane resin is deformed at a temperature higher than the glass transition temperature (hereinafter referred to as Tg), and then the resin is A shape-memory molded article made of a polyurethane resin, which is characterized by being cooled to less than 7 g to fix the deformation, maintaining this state, and recovering to the original shape by heating to 1 g or more before use. It is related to.

Resins such as rubber and plastics have the property of deforming when external force is applied to them at room temperature, and returning to their original state when the external force is removed. None of the conventional polyurethane resins has shape memory properties, such as being deformed by applying an external force, maintaining the deformed shape even after the outer layer is removed, and returning to the original shape when the temperature rises.

Certain metals and shape memory alloys are well known as materials with shape memory properties, and norbornene resins (JP-A-59-5
3528) (Japanese Unexamined Patent Application No. 61-91244),) Lance Isoprene Resin (Unexamined Japanese Patent Application No. 55-93806)
-034150), mixtures of vinyl derivatives and acrylic acid derivatives or synthetic rubbers (JP-A-63-17952
) can only be mentioned.

The present inventor has achieved the present invention as a result of repeated efforts to develop uses for polyurethane resin.

The present invention provides a molded article made of a polyurethane resin having shape memory properties.

The molded article having shape memory properties of the present invention has a Tg of 0 to 100.
℃ range, and has a hardness (Shore D) of 65 or more when less than 7 g, and a hardness (Shore D) of 55 when it is 7 g or more. The above deformation is applied, the deformation is fixed by cooling to less than 7 g, and the deformation is removed by using a method of heating the molded product to 7 g or more before use, and the shape is restored.

The polyurethane resin used in the present invention has a Tg of 0 to
(A temperature in the range of 1°C, preferably 20 to 80°C is used. If the Tg is less than 0°C, even if the molded body with shape memory is cooled to fix the deformation, the deformation will recover at room temperature, so it is not practical. If 1'g is 100° C. or higher, it is not preferable because it exceeds the long-term usable temperature of the polyurethane resin constituting the molded article.

In addition, in order to obtain a molded article having good shape memory properties in the present invention, the hardness (Shore D) of the polyurethane resin constituting the molded article is less than 7 g and is 65 or more, preferably 70 or more, more preferably 73 or more. It is essential that the hardness (Shore D) is less than 55, preferably less than 50, at 7 g or more. Hardness (Shore D) at Tg less than 7^
) If the weight is less than 65, the deformation cannot be fixed even if the molded article is deformed with 7 g or more and then cooled to less than 7 g. Also 7
If the hardness (Shore-D) is 55 or more, it is too hard to cause spontaneous deformation and is not suitable for practical use.

Hereinafter, the structure of the polyurethane resin suitable for the present invention will be explained in detail.

The polyurethane resin used in the present invention has (A) an average functional group number of 2.0 to 6.0 and a number average molecular weight of 250 to 1,00.
It is formed from a composition obtained by reacting a polyhydroxyl compound (B) with an organic polyisocyanate (B) by a known method.

If the average number of functional groups in the polyhydroxyl compound is less than 2.0, it is difficult to obtain sufficient strength of the polyurethane resin and it is difficult to put it into practical use. If the average number of functional groups is 6.0 or more, the Tg of the polyurethane resin exceeds ioo°C, which is not preferable. The preferred number of functional groups is 2.0 to 60, more preferably 2.0 to 4.0.
is within the range of

If the number average molecular weight of the polyhydroxyl compound is 1°000 or more, the Tg of the polyurethane resin is less than 0°C, or 7°C.
The hardness below g (sheer D) is less than 65, which is not preferable. If the number average molecular weight is less than 250, the Tg of the polyurethane resin will exceed 100°C, or the hardness (shear D) of 7 g or more will be 55 or more, which is not preferable.
The preferred number average molecular weight is 250-1.000. More preferably, it is in the range of 30° to 700°.

As the polyhydroxyl compound used in the present invention, those normally used for urethane resins can be used. For example, polyalkylene ether ring-opened polyhydric alcohols and alkylene oxides such as propylene oxides, polyols, polyester polyols produced by the condensation reaction of polyhydric alcohols and low molecular weight carboxylic acids, and hydroxyl-terminated liquid polybutadienes. , acrylic polyol, lactone ring-opened polyester polyol,
Castor oil derivatives and their low hydrous acid group compounds are used, and mixtures of two or more of these can also be used.

The organic polyisocyanate used in the present invention is an aliphatic or aromatic organic compound having at least two incyanate groups as terminal groups, and any polyisocyanate known in the polyurethane resin industry can be used. '-diphenylmethane diisocyanate, tolylene diisocyanate, bosoalkylene polyphenylisocyanate, hexamethylene diisocyanate, naphthylene diisocyanate, bipolar conductors of these polyisocyanates, etc., and mixtures of two or more of these polyisocyanates can be mentioned. You can also use Furthermore, a prepolymer containing an isocyanate group as a terminal group, which is obtained by adding the polyhydroxyl compound, which is arguably insufficient, to the organic polyisocyanate, can also be used.

The polyurethane resin used in the present invention is obtained by the reaction of the polyhydroxyl compound and the organic polyisocyanate, but other auxiliary raw materials may be used in combination as necessary within a range that does not impair the purpose of the present invention. Examples of the auxiliary raw materials include catalysts, fillers, reinforcing solutions, stabilizers, colorants, 1a9F8 agents, foaming inhibitors, and surfactants.

Using the above raw materials, one shift method, prepolymer method,
Molded bodies composed of polyurethane resins are produced by methods known in the polyurethane industry, such as quasi-prepolymer methods. The molded product is produced directly into a sheet, film, or molded product of a predetermined shape by casting or the like. As for the molding conditions, both cold molding and hot molding can be used, and there are no particular limitations as long as the desired effects of the present invention are not achieved.

The temperature at which the molded article of the present invention is deformed during actual use may be at least the Tg of the polyurethane resin constituting the molded article, and is preferably in the range of T g to T gt 30°C. There is no particular restriction on how to give the deformation, and depending on the shape and wall thickness of the molded product, the molded product can be placed under a temperature atmosphere that easily deforms the molded product (for example, in heated air, in a heated liquid, in water vapor, etc.),
Transformations can be applied with bare hands or with appropriate tools.

In order to fix the deformation, the molded body deformed above Tg must be cooled, preferably rapidly, to below 'rg while maintaining the deformation.

In order to remove the deformation from the molded product and return it to a predetermined shape, the temperature is above ゛g, preferably from Tg to T''g+3o.
All you have to do is heat it to ℃, and the deformation will be automatically removed and the shape will be restored. The higher the temperature, the shorter the time it takes for the molded body to recover to its predetermined shape. The means for heating is also not limited as in the case of imparting deformation, and the molded body may be heated using heated air, steam, or the like.

By implementing the present invention, a molded object that has been deformed once can be restored to a predetermined shape, so when using the molded object, if it is difficult to install, assemble, transport, etc. in that shape, the molded object can be deformed and handled. The molded article having shape memory properties of the present invention can be easily used to join pipes, electric wires, etc. Materials and sealing materials, external laminate materials for vibrators and rod-shaped objects, covering materials for objects, tightening materials such as bottles and clamps, construction fixing materials, medical equipment materials such as plaster casts, and folding when not in use. Portable containers and tableware that are sometimes used after recovering their shape;
Materials that require deformation recovery after impact absorption, such as car bumpers, gap prevention materials for house partitions, materials for toys, stationery materials and teaching materials, decorative materials such as artificial flowers and blow sens, and electricity such as heat-sensitive switches. It can be used as parts materials, packing materials, O-rings, molding materials, board surfaces, wig base materials, etc. However, the uses are not limited to these.

The present invention will be specifically explained with reference to the following examples.

Examples 1 to 14 and Comparative Examples 1 to 4 The components shown in Tables 1 to 3 (unit: parts by weight) other than the incyanate component were mixed, then the incyanate component was mixed, and this was mixed into a 200 mm x 200 m In Silicone open mold C with a thickness of 2 mm: It was baked.After being left at room temperature for 5 hours, it was removed from the mold, and then heated at room temperature for 7 hours.
After curing for one day, a molded article made of polyurethane resin was obtained.

7g of the molded product was placed in a BWA dryer at 20° C. and allowed to stand for 10 minutes. Immediately after being taken out of the molded product at room temperature, it was immersed in water while being deformed into a cylindrical shape to be rapidly cooled to fix the deformation. It was evaluated that the fixed deformation of the molded body was maintained for a long time and did not change when the molded body was returned to room temperature again.

This material was placed again in a hot air dryer at 'T'g + 20° C., and it was evaluated that it completely recovered to its original shape.

Performance was evaluated using the following method. The results are shown in Examples 1-
6 and Comparative Example 1 are shown in Table 1, Examples 7 to 9 and Comparative Example 2 are shown in Table 2, and Examples 10 to 14 and Comparative Examples 3 to 4 are shown in Table 3.

The performance evaluation method is as follows.

○Hardness test Shore hardness test method, D type testing machine (JIS-Z-22
46).

O Glass Transition Temperature (1''g) Evaluation was made at the temperature at which the hardness sharply decreases with one temperature increase.

○Determination of presence/absence of shape memory: Shape memory is present, and deformation is fixed at less than 1゛g.
8 or higher, both have complete shape recovery.

None: When the fixed deformation is impossible or incomplete at less than 12 or at room temperature, or when the fixed deformation cannot be recovered at 78 or higher Table *: Measured value at 0°C or when it is incomplete.

○Shape recovery temperature The temperature at which the fixed deformation completely recovers to the original shape when the molded article whose deformation has been fixed at a temperature of less than 7 g is heated from room temperature in a hot air dryer.

○ Compound for polyhydrokimo Polyol 1: Efsenol 400SO (Asahi Glass ■) Sorbitol type OH value 4 Polyol 2: Efsenol 400MP (Asahi Glass ■) Pentaerythritol type 08 value 400 Polyol 3: Efsenol 430 (Asahi Glass ■) Glycerin type OH value 400 Polyol 4: Efsenol 420 (Asahi Glass ■) Diol-based OH value 280 Polyol 5: Efsenol 330 (Asahi Glass ■) Glycerin-based 0H1di530 Polyol 6: Efsenol 1030 (Asahi Glass ■) Glycerin-based OH value 160 ○ Proprietary polyisocyanate isocyanate A: Millionate MR-200 (Japan Polyurethane ■) Isocyanate B: Millionate MTL (Japan Polyurethane ■) 0 Sub-material flooding inhibitor: Baili 7) "I' Powder (Kurita Kogyo Catalyst 2N, N'-tetramethylhexamethylene diamine ( (more margins)

Claims (3)

[Claims] (1) A molded article having shape memory and made of a polyurethane resin having a glass transition temperature (Tg) in the range of 0 to 100°C. (2) The polyurethane resin according to claim 1 has a hardness (Shore D) of 65 below the glass transition temperature (Tg).
As described above, a molded article having shape memory properties characterized by having a hardness (Shore D) of less than 55 at a glass transition temperature or higher. (3) The glass transition temperature (T
g) Deformed at a temperature above, then cooled to below the glass transition temperature (Tg) of the resin to fix the deformation, and heated to above the glass transition temperature (Tg) of the resin before use to restore the original shape. A molded article having shape memory properties, which is characterized by being able to recover.