Shape memory hollow body and method of working the same

DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic drawing showing the steps of fitting an inner pipe of shape memory polyurethane elastomer into a pipe.

Fig. 2 is a sectional view showing the joining of a shape memory hollow body to a pipe.

5. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The conventional shape memory polyurethane elastomer molding depends on rigid allophanate linkages for its

<img file="CA2000201A1_D0001.tif" />

rubber elasticity at a temperature higher than its Tg.

The allophanate linkages result from the intermolecular crosslinking which takes place when excess terminal NCO groups react with urethane linkages. By contrast, the shape memory polyurethane elastomer in the present invention is a thermoplastic chain polymer which is composed of a difunctional isocyanate, polyol, and chain extender according to a specific formulation but contains no excess terminal NCO groups. It is characterized by a specific crystallinity, a Tg approximate to room temperature, and a specific ratio of moduli measured at temperatures above and below the Tg. This polyurethane elastomer has the partial crystallization instead of the intermolecular crosslinking. Therefore, it is a thermoplastic polymer of chain structure; nevertheless, it exhibits rubber elasticity at a temperature higher than its Tg and takes on the as-molded shape and deformed shape at temperatures above and below its Tg. In other words, it has the shape memory function. This thermoplastic polyurethane elastomer can be easily molded into a hollow body by melt molding such as injection molding and extrusion molding.

The thermoplastic polyurethane elastomer in the present invention should preferably have a crystallinity in the range of 3 to 50 wt%. With a crystallinity lower than 3 wt%, the polymer will have a low rubber elasticity at a temperature higher than its Tg. Conversely, with a crystallinity higher than 50 wt%, the polymer will have a high rubber elasticity at a temperature higher than its Tg, with the result that the ratio of moduli at temperatures 10*C above and below its Tg is smaller.

The polyurethane polymer in the present invention is produced from the following raw materials, which are illustrative only and not limitative.

The first raw material is a difunctional isocyanate which is represented by the general formula OCN-R-NCO, where R is a group having no or one or two benzene rings. It includes, for example, 2,4-toluene diisocyanate,

4,4'-diphenylmethane diisocyanate, carbodiimide-modified 4,4'-diphenylmethane diisocyanate, and hexamethylene diis ocyanate.

The second raw material is a difunctional polyol which is represented by the general formula OH-R'-OH, where R' is a group having no or one or two benzene rings The second raw material may also be a reaction product of said difunctional polyol and a difunctional carboxylic acid or cyclic ether. It includes, for example, polypropylene glycol, 1,4-butane glycol adipate, polytetramethylene glycol, polyethylene glycol, and an adduct of bisphenol-A with propylene oxide.

The third raw material is a difunctional chain extender containing active hydrogen which is represented by the general formula 0H-R-0H, where R is a (CH₂)_n group or a group having no or one or two benzene rings. It includes, for example, ethylene glycol, 1,4-butane glycol, bis (2hydroxyethyl)hydroquinone, an adduct of bisphenol-A with ethylene oxide, and an adduct of bisphenol-A with propylene oxide.

The thus produced polyurethane elastomer may be rep10 resented by the following general formula.

HOR'OCONH (RNHCOOR' OCONH) _nRNHC00R0C0NH (RNHCOOpfoCONH) _mRNHCOOROH where m is 1-16 and n is 0-16.

The following illustrates the production of the shape memory polyurethane elastomer. First, a prepolymer is prepared by reacting, in the absence of catalyst, an isocyanate component and a polyol component in the ratio shown in Table 1. To the prepolymer is added a chain extender in the ratio shown in Table 1. The resulting mixture is heat-cured to give the shape memory polyure20 thane elastomer, which has the basic physical properties as shown in Table 1.

In Table 1, Tg represents the glass transition point (°C) and E/E' represents the ratio of the tensile modulus at a temperature 10’C lower than the Tg to the tensile modulus at a temperature 10‘C higher than the Tg. The crystallinity (wt%) was measured by X-ray diffractometry.

The hollow body pertaining to the present invention 5 is made of the above-mentioned shape memory polyurethane elastomer. It remembers its basic shape when it is molded. It is given its second shape (deformed shape) when it is deformed at a temperature higher than its Tg and lower than its molding temperature and then cooled in the deformed state to a temperature lower than its Tg.

Subsequently, the deformed hollow body is combined with another member, and the combination is heated to a temperature higher than its Tg, so that the hollow body restores its basic shape, firmly joining itself to the member.

Table 1

<td> ο</td><td></td><td> in</td><td></td><td></td><td></td><td></td><td> q</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> K d</td><td> CM</td><td> X O)</td><td></td>

<td rowspan="2"> U)</td><td></td><td> in</td><td></td><td></td><td></td><td></td><td> o</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> co</td><td></td>

<td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> d</td><td></td><td></td><td></td><td></td><td> co</td><td> CM</td><td></td>

<td> CO</td><td></td><td> in</td><td></td><td></td><td></td><td></td><td> q</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> 0.51 |</td><td></td><td></td><td></td><td></td><td></td><td> σ&gt;</td><td> 117 |</td><td></td>

<td> r*</td><td></td><td></td><td></td><td></td><td> ιη</td><td></td><td> q</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> v— in</td><td></td><td> m</td><td> O</td><td> in</td>

<td></td><td></td><td></td><td></td><td></td><td> *—</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> d</td><td></td><td> 1</td><td> CM</td><td> CM</td>

<td> to</td><td></td><td></td><td> ιη</td><td></td><td></td><td></td><td> q</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> in</td><td></td><td> to</td><td> 3</td><td></td>

<td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> o</td><td></td><td></td><td> T“</td><td></td>

<td> m</td><td></td><td> in</td><td></td><td></td><td></td><td></td><td> q</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> in</td><td></td><td> V</td><td> 8</td><td></td>

<td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> o</td><td></td><td></td><td> t—</td><td></td>

<td> ΊΤ</td><td> in ▼—</td><td></td><td></td><td></td><td></td><td></td><td> q</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> K d</td><td></td><td> T” 1</td><td> CO CM</td><td> 30 |</td>

<td rowspan="2"> co</td><td></td><td></td><td></td><td> in</td><td></td><td></td><td> q</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> T m</td><td></td><td> m</td><td> O&gt;</td><td> O</td>

<td></td><td></td><td></td><td></td><td></td><td></td><td> ·»”</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> d</td><td></td><td></td><td> (0</td><td> CM</td>

<td> CM</td><td></td><td></td><td></td><td> in</td><td></td><td></td><td></td><td> 3</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> T“ m</td><td></td><td> ο</td><td> CO</td><td> O</td>

<td></td><td></td><td></td><td></td><td> T</td><td></td><td></td><td></td><td> ô</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> d</td><td></td><td> 1</td><td> X</td><td> CM</td>

<td> -</td><td> in</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> q</td><td></td><td> 0.51 |</td><td></td><td></td><td></td><td></td><td> Μ* CM</td><td> 170 i</td><td></td>

<td> .w.</td><td> Μ*</td><td> 8</td><td> 8</td><td> CO O</td><td> 8</td><td> 8</td><td> 8</td><td rowspan="2"> o 8</td><td> 8</td><td> O g</td><td> o g</td><td> | os</td><td> 8</td><td> o g</td><td> 8</td><td> 8</td><td> CM</td><td> O</td><td> 8</td><td> h* CM</td><td> 8</td><td> 8</td><td></td><td></td><td></td>

<td> 5</td><td></td><td> CM</td><td> CM</td><td> CO</td><td></td><td></td><td> X</td><td> (Û</td><td></td><td></td><td> CO</td><td> CO</td><td> t—</td><td> 10</td><td> co</td><td></td><td> o&gt;</td><td></td><td> CO</td><td> CO</td><td> CO</td><td></td><td></td><td></td>

<td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> $</td>

<td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> » $</td>

<td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> c</td>

<td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> Ô</td><td></td><td> rô</td>

<td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> • .</td><td> •</td><td> &lt;Λ</td>

<td></td><td></td><td> Φ</td><td> Φ</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> en</td><td> ty</td><td> £</td>

<td></td><td></td><td> &lt;3</td><td> *ί re</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> H</td><td> LU</td><td> O</td>

<td></td><td></td><td> c</td><td> c</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td></td><td></td><td> re</td><td> re</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> Φ</td><td></td><td></td><td> O</td><td></td><td></td><td> Φ</td><td></td><td></td><td></td>

<td></td><td></td><td> ί (Λ</td><td> £ &lt;Λ</td><td></td><td> φ re</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> oxid</td><td></td><td></td><td> c '5 CT</td><td> « X</td><td></td><td> Ό x O</td><td></td><td></td><td></td>

<td></td><td> e diisocyanate</td><td> Ό Φ C re £ φ ε x c</td><td> nylmethane dii iide-modified)</td><td></td><td> re S' 8 Ό Φ C Φ</td><td> 8 X O) Φ c Φ</td><td></td><td></td><td rowspan="2"> -butaneglycol adipate</td><td></td><td></td><td> lethylene glyco</td><td></td><td></td><td> ne glycol</td><td> A + propylene</td><td> 8 X</td><td> » glycol</td><td> 2 •Ό X -C x £ φ &amp;</td><td> A + ethylene o</td><td></td><td> A + propylene</td><td> ifi •fi</td><td></td><td></td>

<td> o</td><td> c Φ 3 O</td><td> φ -C α 5</td><td> Φ t û?ê ?£</td><td> Q</td><td> £ Φ</td><td> X Q. 2 a x</td><td> p</td><td> p</td><td> n</td><td> o</td><td> ytetram</td><td> o</td><td> o</td><td> yethyle</td><td> phenol-</td><td> en Φ c Φ X</td><td> C re □ 1</td><td> c Ό X .C CM</td><td> O c Φ .c a</td><td> n</td><td> O c Φ a</td><td> 2L e Û.</td><td></td><td></td>

<td> ε</td><td></td><td></td><td> Xg</td><td> ts</td><td> Φ</td><td> O</td><td> c</td><td> c</td><td></td><td> ts</td><td> ts</td><td> O</td><td> ts</td><td> ts</td><td> n</td><td> &lt;0</td><td> F</td><td> ’’t</td><td> W</td><td> to</td><td> a</td><td> &lt;9</td><td> 8</td><td></td><td></td>

<td> re</td><td> CJ</td><td></td><td></td><td> Ή</td><td> -C</td><td> Q.</td><td> Ό</td><td></td><td> v—</td><td> b</td><td> Ό</td><td> Q.</td><td> •o</td><td> X)</td><td> a</td><td></td><td> Φ</td><td> ▼-</td><td> X</td><td></td><td> Ό</td><td> Λ</td><td> w X</td><td></td><td></td>

<td> o</td><td></td><td></td><td></td><td></td><td></td><td></td><td colspan="9"></td><td></td><td></td><td></td><td colspan="2"></td><td></td><td></td><td></td><td></td><td></td>

<td> ε</td><td></td><td></td><td></td><td></td><td></td><td></td><td colspan="9"></td><td></td><td></td><td></td><td colspan="2"></td><td></td><td></td><td> a_</td><td></td><td></td>

<td> TÎ</td><td></td><td></td><td></td><td></td><td></td><td></td><td colspan="9"></td><td></td><td></td><td></td><td colspan="2"></td><td></td><td></td><td> o</td><td></td><td></td>

<td> c (β</td><td></td><td></td><td></td><td></td><td></td><td></td><td colspan="9"></td><td></td><td></td><td></td><td colspan="2"></td><td></td><td></td><td> w Φ</td><td></td><td></td>

<td> ω (0</td><td> (1)</td><td></td><td></td><td></td><td></td><td></td><td colspan="9"></td><td></td><td> «</td><td></td><td colspan="2"></td><td></td><td></td><td> □ re</td><td></td><td></td>

<td> c φ</td><td> re r</td><td></td><td></td><td></td><td></td><td></td><td colspan="9"></td><td></td><td> Φ</td><td></td><td colspan="2"></td><td></td><td></td><td> &gt; Ή</td><td></td><td></td>

<td> re</td><td> re</td><td></td><td></td><td></td><td></td><td></td><td colspan="9"></td><td></td><td> X</td><td></td><td colspan="2"></td><td></td><td></td><td> 2</td><td></td><td></td>

<td> Ε %</td><td rowspan="2"> &amp; o w</td><td></td><td></td><td></td><td></td><td> o X</td><td colspan="9"></td><td></td><td> c ra</td><td></td><td colspan="2"></td><td></td><td></td><td> □ V) re</td><td></td><td></td>

<td> re</td><td></td><td></td><td></td><td></td><td> n</td><td colspan="9"></td><td></td><td> r</td><td></td><td colspan="2"></td><td></td><td></td><td> φ</td><td></td><td></td>

<td> t£</td><td> δ</td><td></td><td></td><td></td><td></td><td> a.</td><td colspan="9"></td><td></td><td> o</td><td></td><td colspan="2"></td><td></td><td></td><td> i</td><td></td><td></td>

Table 1 (continued)

<td> o CM</td><td></td><td> in co</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> q</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> 0.36 |</td><td></td><td></td><td> in γ</td><td> o co</td><td> m CM</td>

<td> 0) V“</td><td></td><td> I 1.35</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> q</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> 0.36 |</td><td></td><td></td><td> 00 7</td><td> 29 |</td><td> in CM</td>

<td> GO</td><td></td><td> in co</td><td></td><td></td><td></td><td></td><td></td><td></td><td> q V—</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> 0.36 j</td><td></td><td></td><td> o T—</td><td> 8</td><td></td>

<td> h* V“</td><td></td><td> | 1.35</td><td></td><td></td><td></td><td></td><td></td><td> q</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> 0.36 |</td><td></td><td></td><td> -22 |</td><td> V“ GO</td><td></td>

<td> CO V”</td><td></td><td> | 1.35</td><td></td><td></td><td></td><td></td><td> q V“</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> 0.36 |</td><td></td><td></td><td> in</td><td> co</td><td> in CM</td>

<td> in</td><td></td><td> 00</td><td></td><td></td><td></td><td></td><td> q</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> T“ 00 Ô</td><td></td><td></td><td> in CM</td><td> co in</td><td> 20 |</td>

<td> V”</td><td></td><td> CM</td><td></td><td></td><td></td><td></td><td> q</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> 0.21 |</td><td></td><td></td><td> I</td><td> in o</td><td></td>

<td> co</td><td></td><td> in</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> q T“</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> co I</td><td> CM T—</td><td> o co</td>

<td> CM V“</td><td></td><td> in</td><td></td><td></td><td></td><td></td><td> q v—</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> 0.51 |</td><td></td><td></td><td></td><td> N 1</td><td> CD</td><td> o CM</td>

<td> -</td><td></td><td> in</td><td></td><td></td><td></td><td></td><td> q</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> 0.51 |</td><td></td><td></td><td> CO T·</td><td> V</td><td></td>

<td> § 2</td><td> | 174</td><td> | 250</td><td> 290</td><td> εοε |</td><td> | 168</td><td> | 400</td><td> I 700</td><td> o s V</td><td> 009 |</td><td></td><td> | 2000 I</td><td> 8 (0</td><td> I 850 I</td><td> o 8</td><td> 600 |</td><td> 800 |</td><td> CM co</td><td> 90 |</td><td> 00 o&gt; V”</td><td> 327 |</td><td> 8 CO</td><td> 8 CO</td><td rowspan="2"> o O)</td><td rowspan="2"> &amp;</td><td rowspan="2"> ' Crystallinity (wt%) 1</td>

<td rowspan="3"> | Raw materials and molar ratio</td><td rowspan="2"> | 2,4-toluene diisocyanate</td><td rowspan="2"> | 4,4’-diphenylmethane diisocyanate</td><td rowspan="2"> 4,4’-diphenylmethane diisocyanate (carbodiimide-modified)</td><td rowspan="2"> | ditto</td><td rowspan="2"> | bexamethylene diisocyanate</td><td rowspan="2"> | polypropylene glycol</td><td rowspan="2"> | ditto</td><td rowspan="2"> | ditto J</td><td rowspan="2"> | 1,4-butaneglycol adipate j</td><td rowspan="2"> | ditto |</td><td rowspan="2"> | ditto |</td><td rowspan="2"> polytetramethylene glycol |</td><td rowspan="2"> | ditto |</td><td rowspan="2"> | ditto |</td><td rowspan="2"> | polyethylene glycol |</td><td rowspan="2"> bisphenol-A + propylene oxide |</td><td rowspan="2"> 8 £« O) 8 ω &gt;, I</td><td rowspan="2"> ! 1,4-butane glycol |</td><td rowspan="2"> ' bis(2-hydroxyethyl)hydroquinone |</td><td rowspan="2"> bisphenol-A + ethylene oxide |</td><td rowspan="2"> ditto |</td><td rowspan="2"> bisphenol-A + propylene oxide |</td>

<td colspan="3" rowspan="2"> Measured values of physical properties</td>

<td colspan="5"> Diisocyanate</td><td colspan="11"> Polyol ί I</td><td colspan="6"> « c o X &lt;D c -G O</td>

Table 1 (continued)

<td> o co</td><td> CM</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> p</td><td></td><td></td><td> 0.21 |</td><td></td><td></td><td></td><td> O)</td><td> o</td><td> in</td>

<td> Oi CM</td><td> CO T~</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> p tr·</td><td></td><td></td><td> 0.31 |</td><td></td><td></td><td></td><td> σ&gt;</td><td> 8</td><td> in</td>

<td> | 28</td><td> X</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> p</td><td></td><td></td><td> 0.41 |</td><td></td><td></td><td></td><td> CM</td><td> « T“</td><td> in</td>

<td> CM</td><td> in</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> p</td><td></td><td></td><td> 0.51 |</td><td></td><td></td><td></td><td> Φ CM</td><td> 5</td><td> o</td>

<td> | 26</td><td></td><td> in co</td><td></td><td></td><td></td><td> p</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> 0.36 |</td><td></td><td></td><td> CO CM</td><td> 8</td><td> in</td>

<td> in CM</td><td></td><td> in</td><td></td><td></td><td></td><td></td><td> p</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> 0.35 |</td><td></td><td></td><td> GO</td><td> 8</td><td> m</td>

<td> V CM</td><td></td><td> in</td><td></td><td></td><td></td><td></td><td> p</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> 0.43 |</td><td></td><td></td><td> m</td><td> CO co</td><td> in CM</td>

<td> co CM</td><td></td><td> I 1.35</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> p</td><td></td><td></td><td></td><td></td><td></td><td> 0.36 I</td><td></td><td></td><td> GO co</td><td> o</td><td></td>

<td> t 22</td><td></td><td> | 1.35</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> p v—</td><td></td><td></td><td></td><td></td><td></td><td></td><td> 0.36 |</td><td></td><td></td><td> o co 1</td><td> CO</td><td> in CM</td>

<td> CM</td><td></td><td> | 1.35</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> p</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> 0.36 |</td><td></td><td></td><td> 00 1</td><td> co co</td><td> in CM</td>

<td> | M.W.</td><td> | 174</td><td> | 250</td><td> 290</td><td> | 303</td><td> 1 ⁸⁹¹ 1</td><td> 1 oof 1</td><td> 1 °°^z 1</td><td> o 8</td><td> | 600 |</td><td> o 8</td><td> o 8 CM</td><td> 650 |</td><td> 8 GO</td><td> o 8</td><td> 600 |</td><td> | 008</td><td> CM ω</td><td> o O)</td><td> 198 |</td><td> CM CO</td><td> 8 CO</td><td> 8 CO</td><td rowspan="2"> p F</td><td rowspan="2"> s</td><td rowspan="2"> Crystallinity (wt%) I</td>

<td rowspan="3"> | Raw materials and molar ratio</td><td rowspan="2"> | 2,4-toluene diisocyanate</td><td rowspan="2"> | 4,4’-diphenylmethane diisocyanate</td><td rowspan="2"> Φ ft c 03 £ w Φ φ 1? s-s</td><td rowspan="2"> | ditto</td><td rowspan="2"> | hexamethylene diisocyanate</td><td rowspan="2"> | polypropylene glycol</td><td rowspan="2"> | ditto j</td><td rowspan="2"> ditto</td><td rowspan="2"> 1,4-butaneglycol adipate |</td><td rowspan="2"> | ditto |</td><td rowspan="2"> ê Ό</td><td rowspan="2"> i polytetramethylene glycol |</td><td rowspan="2"> ditto |</td><td rowspan="2"> , ditto |</td><td rowspan="2"> polyethylene glycol |</td><td rowspan="2">¹ bisphenol-A + propylene oxide |</td><td rowspan="2"> ethylene glycol |</td><td rowspan="2"> 1,4-butane glycol |</td><td rowspan="2"> bis(2-hydroxyethyl)hydroquinone |</td><td rowspan="2"> bisphenol-A + ethylene oxide |</td><td rowspan="2"> ditto |</td><td rowspan="2"> bisphenol-A + propylene oxide I</td>

<td colspan="3" rowspan="2"> Measured values of physical properties</td>

<td colspan="5"> Diisocyanate</td><td colspan="11"> Polyol</td><td colspan="6"> Chain extender</td>

Table 1 (continued)

<td> 1 40 I</td><td></td><td> 5&gt;</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> q</td><td></td><td></td><td> 0.81 |</td><td></td><td></td><td></td><td> CO xr</td><td> CM in</td><td> in</td>

<td> 1 39</td><td></td><td> m</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> q</td><td></td><td></td><td> 0.51 |</td><td></td><td></td><td></td><td> o</td><td> 8</td><td> in</td>

<td> I 38</td><td></td><td> in</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> q</td><td></td><td> 0.51 |</td><td></td><td></td><td></td><td></td><td> in co</td><td> Si 1“</td><td> o</td>

<td> co</td><td></td><td> | 1.68</td><td></td><td></td><td></td><td></td><td> o</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> 55 d</td><td></td><td></td><td></td><td></td><td></td><td> CM</td><td> 8</td><td> o</td>

<td> | 36</td><td></td><td> | 1.59</td><td></td><td></td><td></td><td></td><td> q V</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> V· in d</td><td></td><td></td><td></td><td></td><td></td><td> V-</td><td> 8</td><td> in</td>

<td> | 35</td><td></td><td></td><td></td><td></td><td></td><td></td><td> q v-</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> d</td><td></td><td></td><td></td><td></td><td></td><td> in</td><td> 122 |</td><td> in T—</td>

<td> co</td><td></td><td> co</td><td></td><td></td><td></td><td></td><td> q</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> co d</td><td></td><td></td><td></td><td></td><td></td><td> CM</td><td> CO 00</td><td> 20 |</td>

<td> co co</td><td> in</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> q t^-</td><td></td><td></td><td> 0.51 |</td><td></td><td></td><td></td><td> CM CM</td><td> bO r-</td><td> in</td>

<td> 1 32</td><td></td><td> | 1.68</td><td></td><td></td><td></td><td></td><td> q</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> in d</td><td></td><td></td><td> 8 r-</td><td> o CM</td>

<td> 5</td><td></td><td> | 1.59</td><td></td><td></td><td></td><td></td><td> q</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> m d</td><td></td><td> o</td><td> 8</td><td> in</td>

<td> | M.W.</td><td> | 174</td><td> | 250</td><td> 290</td><td> I 303</td><td> 8</td><td> I 400</td><td> I 700</td><td> o 8</td><td> | 009 |</td><td> o 8</td><td> | 2000 I</td><td> [ 650 |</td><td> 850 |</td><td> o 8</td><td> | 009</td><td> 800 |</td><td> CM co</td><td> o</td><td> 198 |</td><td> r*. CM co</td><td> 8 co</td><td> 8 &lt;0</td><td></td><td rowspan="2"> 1 &amp;</td><td rowspan="2"> Crystallinity (wt%) I</td>

<td rowspan="3"> | Raw materials and molar ratio</td><td rowspan="2"> J 2,4-toluene diisocyanate</td><td rowspan="2"> I 4,4’-diphenylmethane cfiisocyanate</td><td rowspan="2"> 4,4'-diphenylmethane diisocyanate (carbodiimide-modified)</td><td rowspan="2"> | ditto</td><td rowspan="2"> | hexamethylene diisocyanate</td><td rowspan="2"> I polypropylene glycol</td><td rowspan="2"> I ditto</td><td rowspan="2"> | ditto</td><td rowspan="2"> 1,4-butaneglycol adipate</td><td rowspan="2"> ditto</td><td rowspan="2"> ditto</td><td rowspan="2"> polytetramethylene glycol |</td><td rowspan="2"> ditto |</td><td rowspan="2"> ditto |</td><td rowspan="2"> polyethylene glycol |</td><td rowspan="2"> bisphenol-A + propylene oxide |</td><td rowspan="2"> 8 O) Φ c 1</td><td rowspan="2"> 1,4-butane glycol |</td><td rowspan="2"> Φ c o c '5 σ 9 Ό £ &gt;&gt; £ &amp; e Ό &gt;, _c 1 CM 3</td><td rowspan="2"> bisphenol-A + ethylene oxide |</td><td rowspan="2"> ditto |</td><td rowspan="2"> bisphenol-A + propylene oxide |</td><td> p t?</td>

<td colspan="3" rowspan="2"> Measured values of physical properties</td>

<td colspan="5"> Diisocyanate</td><td colspan="11"> Polyol</td><td colspan="4"> « c Φ X Φ c s O</td><td></td><td></td>

EXAMPLES

The invention will be described in more detail with reference to the following examples, which are not intended to restrict the scope of the invention.

Example 1

In this example, a hollow body (inner pipe) made of the shape memory polyurethane elastomer was fitted into an outer pipe according to the following procedure.

First, a polymer having a Tg of 48‘C was prepared by prepolymer process according to the formulation of sample No. 40 shown in Table 1. The polymer was made into a cylindrical hollow body 2a having an outside diameter of 10.4 cm and a wall thickness of 5 mm by extrusion molding.

This cylindrical hollow body 2a was heated to about 65‘C and then collapsed by pressing. It was cooled to about 40 °C in the collapsed state so that it was set deformed. Thus there was obtained a collapsed hollow body lb.

The collapsed hollow body lb was inserted into a steel pipe 2 having an inside diameter of 10 cm. (The resulting combination is indicated by 3a.)

The collapsed hollow body 2b inserted into the steel pipe 3a was heated by blowing hot air (about 65°C), so that it restored its original cylindrical shape. Thus there was obtained a composite pipe 3b composed of a steel pipe 2 and a cylindrical hollow body la of polyurethane elastomer which was firmly bonded to the inside of the steel pipe.

This example shows that the use of the shape memory function overcomes the difficulty which was encountered in the past when the inside of a small steel pipe was coated with a polyurethane elastomer.

Example 2

In this example, a pipe made of the shape memory polyurethane elastomer was joined to another pipe as shown in Fig. 2.

A polymer having a Tg of 40 °C was prepared by prepolymer process according to the formulation of sample No.

shown in Table 1. The polymer was molded into a straight pipe (not shown) having an outside diameter of 5 cm and a wall thickness of 3 mm. This straight £>ipe remembers its as-molded shape. The end 4 (3 cm long) of the pipe was heated to about 60 °C and then contracted until the outside diameter was 4 cm. The pipe was cooled to about 35 °C, with the end contracted, so that the contracted shape was set. Thus there was obtained a pipe 5 as shown in Fig. 2.

The end 4 of the pipe 5 was inserted into a pipe 6 having an inside diameter of 4.5 cm. When they are heated to about 60 °C, the end of the pipe 5 restored its original shape, joining itself firmly to the inside of the pipe 6. The above-mentioned joining procedure may be applied to joining an elbow made of shape memory polymer to a steel pipe.

As the above-mentioned examples show, the thermoplastic polyurethane elastomer having the shape memory function can be molded into a hollow body of any shape by melt molding such as injection molding, extrusion molding, and blowing molding.

In addition, the shape memory hollow body of the present invention remembers its basic shape, takes on its second shape (e.g., reduced or enlarged diameter, and bending), and restores its basic shape after it has been combined with another member. This property makes it pos15 sible to join the hollow body firmly to another member.

21326-135

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE

PROPERTY OR PRIVILEGE IS