JP4760149B2 - Shape memory resin having shape recovery ability and excellent shape recovery ability in two steps, and molded article comprising cross-linked product of the resin - Google Patents

Description

  The present invention relates to a resin composition that can be remolded and has an excellent shape recovery ability in two stages. The present invention also relates to a molded product composed of a crosslinked product of the molded resin composition, a deformed molded product, and methods for using them.

  Conventionally, there are alloy materials and resin materials that show shape memory properties. Shape memory alloys are used for pipe joints and orthodontics, and shape memory resins are used for medical purposes such as heat-shrinkable tubes, clamping pins, laminates, and casts. Used for equipment. Compared to shape memory alloys, shape memory resins can be processed into complex shapes, have a high shape recovery rate, are lightweight, can be freely colored, and are low cost. Is attracting attention.

  Shape memory resin can be fixed to a desired shape by being deformed by applying a predetermined temperature to the resin, and then cooled to room temperature, and then restored to its original shape by heating again. . The shape memory resin is a non-phase fluid which is fluidized at a certain temperature (glass transition temperature (Tg) or melting point (Tm) inside the reversible phase) above a stationary phase consisting of physical or chemical bonding sites (crosslinking points). It is comprised from the reversible phase which consists of a bridge | crosslinking part, It is characterized by the above-mentioned.

  The mechanism of the shape memory resin will be described in more detail, but the following steps 1 to 3 realize the provision of the shape memory, the deformation of the molded product, and the recovery of the memory shape. FIG. 1 is a conceptual diagram.

1. Molding process When the shape memory resin is molded by a predetermined method (heating, melting, solidifying), the initial state (original) consisting of a stationary phase and a reversible phase (hard) (Fig. (A) and partially enlarged view (b) ) Is stored.

2. Deformation of molded product In order to transform a molded product into an arbitrary shape, the stationary phase is not melted, but only the reversible phase is melted, that is, heated to Tg or Tm above the reversible phase and shifted to the reversible phase (soft). It can be deformed by applying an external force in this state ((d)). When the deformed molded article is cooled to less than Tg or less than Tm (or less than Tc (crystallization temperature)), the reversible phase is also completely solidified and fixed in a deformed state ((e) in the figure).

3. Recovery of Memory Shape The shape of the molded product deformed into an arbitrary shape is maintained in its deformed state by a reversible phase that is temporarily forcedly fixed. Accordingly, when the temperature reaches a temperature at which only the reversible phase is softened by heating, the resin exhibits a rubber-like characteristic and becomes a stable state and recovers its original shape ((c) in the figure). Further, by cooling to less than Tg or less than Tm (or below Tc (crystallization temperature)), the molded body in the initial state shown in FIG.

  Here, it is known that the stationary phase is classified into a thermosetting type and a thermoplastic type depending on the type of cross-linking, and each has advantages and disadvantages. Moreover, it can classify | categorize into Tg type and Tc type by the method of solidifying a reversible phase, and each has the characteristic.

  First, a method for crosslinking the stationary phase will be described. The stationary phase of the thermosetting shape memory resin consists of a crosslinked structure by covalent bonds. As an advantage of the thermosetting type, it has a high effect of preventing the resin from flowing, has an excellent shape recovery force and dimensional stability, and has a high recovery speed. On the other hand, due to the covalent bond crosslinking, there is a disadvantage that remolding is impossible, that is, recycling is not possible.

  For example, as a specific example of a conventional thermosetting shape memory resin, trans-1,4-polyisoprene (Patent Document 1: Japanese Patent Application Laid-Open No. 62-192440) can be cited. This is a resin obtained by cross-linking trans-1,4-polyisoprene with sulfur or peroxide, and the stationary phase is a cross-linked site, and the reversible phase is a crystal portion of trans-1,4-polyisoprene. Although this resin is excellent in shape recovery power, it cannot be remolded as described above and is inferior in recyclability due to covalent bond crosslinking.

  On the other hand, the stationary phase of the thermoplastic shape memory resin is composed of a crystal part, a glassy region of a polymer, entanglement of polymers, metal cross-linking and the like. Since these stationary phases melt by heating, they have the advantage that they can be reshaped, ie recycled. However, since the bonding force of the thermoplastic stationary phase is weaker than that of the thermosetting type which is covalent bond crosslinking, it has a disadvantage that it is inferior in shape recovery power to the thermosetting type.

  For example, polynorbornene (Patent Document 2: Japanese Patent Application Laid-Open No. 59-53528) is an example of a conventional thermoplastic shape memory resin. It is described that the entanglement between the polymers is a stationary phase, and the site without the entanglement is a reversible phase and has shape memory. However, this shape memory resin has a problem that the shape recovery time is long and the molecular weight is very high, so that the processability is poor.

  An example of polyurethane (Patent Document 3: Japanese Patent Application Laid-Open No. 2-92914) is also known. The stationary phase is a crystalline part and the reversible phase is an amorphous part. However, this shape memory resin also has a long shape recovery time. Moreover, since tensile strength is very weak, it is difficult to use for the member for electronic devices.

  A styrene-butadiene copolymer (Patent Document 4: JP-A 63-179955) is also known. The stationary phase is a glassy region of polystyrene, and the reversible phase is a crystal part of transpolybutadiene. However, this shape memory resin also has a problem that the shape recovery time is long and the shape recovery rate is low.

  A method for improving the shape memory characteristics of the thermoplastic shape memory resin has also been proposed. For example, in Patent Document 5 (Patent Publication No. 2692195), the shape recovery rate and recovery are achieved by hydrogenating 80% or more of the olefinic unsaturated bonds in the ternary block copolymer similar to Patent Document 4. It is said that a shape memory resin excellent in time can be provided. However, in Non-Patent Document 1 (Masao Karushi, “Material Development of Shape Memory Polymer”, CMC, pp. 30-43, published in 1989), styrene-butadiene-based thermoplastic shape memory resin is shaped by repeated deformation. It has been pointed out that the memory recovery rate decreases.

  Next, a method for fixing the reversible phase will be described. Resins can be classified into crystalline resins and amorphous resins. Tc (crystallization temperature) is specific to crystalline resins, whereas Tg (glass transition temperature) is the amorphous phase of resin (amorphous). This phenomenon is caused not only by the amorphous resin but also by the amorphous part of the crystalline resin, and is therefore present in any resin.

  Tc (or Tm (crystalline phase melting temperature)) is a phenomenon caused by freezing (or melting) of molecular motion due to crystallization of the resin, and the elastic modulus of the resin increases in a temperature range below Tc (or Tm). It becomes possible to fix the deformed shape. Since the degree of increase in the elastic modulus varies depending on the ratio of crystallized portions (crystallinity) of the crystalline resin, the hardness of the entire resin depends on the type of resin and the crystallization conditions. That is, it is possible to design a soft material in the operating temperature range. In many cases, the shape memory alloy is used for soft characteristics such as a frame of glasses or an antenna of a mobile phone. If a shape memory resin that is soft at room temperature is obtained, it can be used as an inexpensive and lightweight material instead of these shape memory alloys. In addition, when the shape is fixed by Tc (or Tm), since the transition is generally faster than that of Tg (because of transition at a narrow temperature range), it is excellent in practicality as a shape memory resin (Non-patent Document 4). Lenden et al., Angew. Chem. Int. Ed., 2002, 41, 2034-2057).

  Examples of immobilizing the reversible phase by crystallization include the above-mentioned trans-1,4-polyisoprene (Patent Document 1: Japanese Patent Laid-Open No. 62-192440), styrene-butadiene copolymer (Patent Document 4: JP, 63-179955, A) is mentioned, but it has already been mentioned that there are problems with recyclability, recovery time, and recovery power.

  In recent years, there has been great interest in environmental issues, and the recyclability of materials has become important. However, none of the conventional shape memory resins achieves recyclability and excellent shape recovery force at the same time for the above reasons. Therefore, it has been difficult to use a conventional shape memory resin in the field of a molded product requiring recyclability and excellent shape recovery ability, such as a member for electronic equipment.

  As an example in which a thermoreversible cross-linked structure is introduced into a shape memory resin to impart molding processability and recyclability, there is JP-A-2-258818. As thermoreversible covalently crosslinked structures, covalently crosslinked structures using ionic crosslinking groups such as carboxyl groups, Diels-Alder reactions, and dimerization reactions of nitroso groups are disclosed. The claims include a cross-linked product obtained by using a block copolymer of an aromatic vinyl monomer and a conjugated diene monomer as a base polymer, and cross-linking the base polymer thermoreversibly, The glass transition temperature (Tg) of the dissociated polymer of the crosslinked product (the base polymer) is higher than the dissociation (cleavage) temperature (Td) of the thermoreversible crosslinking contained in the crosslinked product, and the glass transition temperature is It is characterized by being in the range of 70 ° C to 140 ° C.

  In the lower right column of page 3, the dissociation temperature of thermoreversible crosslinking should be lower than the glass transition temperature of the dissociated polymer, but practically the dissociation temperature is 10 ° C. or higher than the glass transition temperature of the dissociated polymer. It is preferably low. " In this block copolymer, similarly to the styrene-butadiene copolymer (Patent Document 4), an aromatic resin having a Tg of about 100 ° C. serves as a stationary phase. On the other hand, a crystalline diene polymer having a melting point lower than the Tg of the aromatic resin works as a reversible phase. The thermoreversible covalently crosslinked structure is introduced into the double bond part in the diene polymer. When heated to Td or higher, the bond (crosslinked) is cleaved, deformed in this state, and then cooled to Td or lower. By doing so, re-bonding (re-crosslinking) and shape memory property are obtained, and by heating to Tg or more of the aromatic resin, moldability is improved and re-molding is possible. That is, in this shape memory resin, as shown in FIG. 2, the resin part becomes a stationary phase and the cross-linked part functions as a reversible phase ((a) in FIG. 2), and the cross-linking is cleaved by heating to Td or higher. (Drawing (b)), further maintaining the heating state and applying external force to deform (Drawing (c)), cooling to below Td and re-crosslinking to show in (d) The shape is stored as follows. In order to recover the shape, it is carried out by heating again to Td or higher to cleave the bridge, and then cooled to return to the original shape. By heating to Tg or more of the aromatic resin at the time of re-molding, the resin portion of the stationary phase has fluidity and can be re-molded as shown in FIG.

  However, since the crosslinking is cleaved at the time of shape recovery, this resin is a thermoplastic type, and an excellent shape recovery power cannot be obtained, and usable resins and thermoreversible binding cross-linked structures are limited. In addition, since the dissociation temperature of the crosslinked structure due to the covalent bond is high (Diels-Alder type: 120 to 160 ° C., nitroso group type: 70 to 160 ° C.), there are actually restrictions on resins and crosslinking sites that satisfy the conditions of this patent. In particular, since the temperature margin during shape memory is in a very narrow range, it is not practical.

  By the way, as an example using thermoreversible reaction for crosslinking, Non-Patent Document 3 (Engle et al., J. Macromol. Sci. Re. Macromol. Chem. Phys., Vol. C33, No. 3, pages 239-257, 1993). (Annual) describes Diels-Alder reaction, nitroso dimerization reaction, esterification reaction, ionene reaction, urethanization reaction, and azlactone-phenol addition reaction.

  Non-Patent Document 4 (Yoshinori Nakane and Masahiro Ishidoya et al., Coloring Materials, Vol. 67, No. 12, pp. 766-774, published in 1994); Non-Patent Document 5 (Yoshinori Nakane and Masahiro Ishidoya et al., Coloring materials, 69, No. 11, pp. 735-742, published in 1996); Patent Document 7 (Japanese Patent Laid-Open No. 11-35675) describes a thermoreversible cross-linking structure utilizing a vinyl ether group.

  In addition, an example in which a reversible reaction by an esterification reaction of an acid anhydride is used to improve heat resistance and recyclability is described in Patent Document 8 (Japanese Patent Application Laid-Open No. 11-106578), and a carboxylic acid is added to a vinyl polymerization compound. A technique for introducing an anhydride and crosslinking with a linker having a hydroxy group is shown.

  However, there is no description about shape memory property, and there is no example used as shape memory resin.

  Shape memory resins using various biodegradable polymers have also been proposed in order to deal with environmental problems on the premise that they are not recycled but discarded. For example, Patent Document 9 (Japanese Patent Application Laid-Open No. 9-221539) discloses a biodegradable shape memory resin composed of an aliphatic polyester resin such as a polylactic acid resin. However, since these are also thermoplastic resins, their shape recovery force and recovery speed are insufficient.

  A shape memory resin using a biodegradable heat or photocurable resin is described in Patent Document 10 (Japanese Patent Publication No. 2002-503524). FIG. 5 of this patent document shows shape memory by photocrosslinking and shape recovery by crosslink cleavage by heat or light. In addition, although a plurality of shape memories are described, this is a polymer blend obtained by simply blending thermoplastic shape memory resins, and in this method, excellent shape memory properties due to covalent cross-linking and Restorability cannot be obtained. Further, there is no description about recycling of the curable resin.

JP 62-192440 A JP 59-53528 A JP-A-2-92914 JP-A 63-179955 Patent Publication No. 2692195 JP-A-2-258818 JP 11-35675 A JP-A-11-106578 JP-A-9-221539 Special table 2002-503524 gazette Masao Karabushi, “Material Development of Shape Memory Polymer”, CMC, 30-43, published in 1989 A. Lenden et al., Angew. Chem. Int. Ed., 2002, 41, 2034-2057 Engle et al. Macromol. Sci. Re. Macromol. Chem. Phys. , C33, No.3, pp.239-257, published in 1993 Yoshinori Nakane and Masahiro Ishidoya et al., Coloring Materials, Vol. 67, No. 12, pp. 766-774, published in 1994 Yoshinori Nakane and Masahiro Ishidoya et al., Coloring Material, Vol. 69, No. 11, pp. 735-742, 1996

  In addition to the conventional shape memory characteristics, if another shape memory is possible, the application can be further expanded. For example, a conventional heat-shrinkable tube is used to join two pipes by restoring the memorized shrinkage shape by heating, but it is necessary to cut the tube when removing the pipe. It was. On the other hand, it is possible to make a tube that uses a resin capable of shape memory in two stages and restores to a contracted shape by heating in a low temperature region, and conversely restores to an expanded shape by heating in a high temperature region. is there. If this is used, the tube once used for joining can be expanded and removed by further heating. Further, in the case of a tightening pin, conventionally, it was used for pin tightening by heating and bending, and it was simply removed by restoring it to its original straight shape by heating again. If the two-stage shape memory resin is used, the pin is automatically bent and tightened by heating in a low temperature region, and then the pin is again straightened and removed by heating in a higher temperature region. In this way, a wide range of applications not found in conventional shape memory alloys and shape memory resins can be expected.

  An object of the present invention is to provide a shape memory resin that is soft at room temperature, can be remolded, and has a shape recovery ability excellent in two stages, and a molded body made of a crosslinked product of the resin.

  The present inventor believes that a shape memory resin having a thermoreversible cross-linking structure in which a resin has a Tg of normal temperature or lower, is covalently crosslinked at a temperature of Tm (or Tc) or higher, and is cleaved at a molding temperature is It has been found that it can be used for molded products that require excellent shape recovery force and re-formability, such as equipment members. It has also been found that a soft material can be designed by controlling the elastic modulus at room temperature to be low, and that a shape material can be memorized in two stages and a hard material can be obtained by setting the temperature to Tg or lower. ing. Furthermore, by using a plant-derived resin as a raw material, it is possible to obtain a material having further excellent environmental compatibility.

That is, this invention consists of the following structures.
(1) Glass transition temperature (Tg) is in the range of −70 ° C. or higher and 10 ° C. or lower, crystal melting temperature (Tm) and crystallization temperature (Tc) are in the range of 40 ° C. or higher and 200 ° C. or lower. A shape memory resin having a thermoreversible cross-linked structure that is cleaved by the above, wherein the thermoreversible cross-linked structure has a cleavage temperature (Td) in the range of 50 ° C. or higher and 300 ° C. or lower and Tm + 10 ° C. ≦ Td. The deformation temperature at the time of shape recovery at the time of shape recovery is not less than Tm and less than Td, and the deformation temperature at the time of shape recovery of the second shape at the time of shape recovery is not less than Tg and less than Tm. Shape memory resin capable of shape memory.

(2) The thermoreversible cross-linking structure is at least one selected from the group consisting of Diels-Alder type, nitroso dimer type, acid anhydride ester type, urethane type, azlactone-hydroxyaryl type, and carboxyl-alkenyloxy type. (1) The shape memory resin according to (1).

(3) The shape memory resin according to (1) or (2), wherein the resin is remoldable at a temperature equal to or higher than Td and lower than a decomposition temperature of the resin.

(4) The shape memory resin according to any one of (1) to (3), wherein the resin has biodegradability.

(5) The shape memory resin according to (4), wherein the resin is a resin derived from a plant-derived resin.

(6) The shape memory resin according to (5), wherein the resin is a resin using polybutylene succinate or polyhydroxyalkanoate as a raw material.

(7) The shape memory resin according to (6), wherein the resin is a Diels-Alder type cross-linked product of polybutylene succinate or polyhydroxyalkanoate in a cooled state.

(8) The shape memory resin according to any one of (1) to (7), wherein the resin has a Tm of 40 ° C. or higher and 120 ° C. or lower.

(9) The shape memory resin according to any one of (1) to (8), wherein the resin has a molecular weight of one or more precursors of 500 or more and 100,000 or less.

(10) A molded article comprising a cross-linked product of the shape memory resin.

(11) The cross-linked product of the shape memory resin is molded into a predetermined first shape to be memorized at a temperature of Td or higher and lower than the decomposition temperature of the resin, and then the obtained molded body is Tm or higher, A molded body characterized by imparting a second shape by applying a deformation at a temperature lower than Td, cooling to a temperature equal to or lower than Tc, and fixing the deformed shape.

(12) The molded body according to (11) is imparted with a third shape by being deformed at a temperature of Tg or more and less than Tm, and cooled to a temperature of less than Tg to fix the deformed shape. Molded body.

(13) The third shape molded body according to the above (12) is recovered to the original second shape memorized by heating to a temperature of Tg or more and less than Tm, and Tm or more and less than Td. A method of using a shape memory resin molded product, wherein the molded product is restored to a first shape by heating to a temperature.

(14) A method for regenerating a shape memory resin molded product, comprising melting and remolding the molded product according to (11) or (12) at a temperature equal to or higher than Td and lower than a decomposition temperature of the resin.

  Since the shape memory resin of the present invention is a thermosetting resin at the time of shape memory and recovery, it has excellent shape recovery ability, while it becomes a thermoplastic mold at the time of molding and remolding, so that it is molded and remolded. It is an excellent resin. Therefore, it is useful as a molded article for electronic device members used near room temperature.

  Specifically, a shape memory resin in which a covalent thermoreversible reaction is introduced into a cross-linked site is provided. A thermoreversible reaction refers to a reaction in which a bond is cleaved at a predetermined temperature and recombined upon cooling. By cross-linking the resin by a thermoreversible reaction, the thermoreversible cross-linking site becomes a stationary phase and the resin becomes a reversible phase, and shape memory property is obtained. Furthermore, since it is covalently crosslinked in the practical temperature range, it functions as a thermosetting mold, and at the time of molding and remolding, the bond is cleaved by heating and functions as a thermoplastic mold. It becomes a shape memory resin with the advantages of excellent moldability and recyclability. Moreover, since it recombines at the time of cooling and returns to the thermosetting type, a shape memory resin equivalent to that before molding can be obtained, and the shape recovery rate does not decrease due to repeated deformation. Since a three-dimensional cross-linking structure using a covalent bond rather than a crystal phase is used for forming the first shape memory, a material having a low elastic modulus such as rubber can be easily obtained in the intermediate temperature range. Tc that fixes only the crystal phase can be used instead of Tg that firmly restrains the entire resin. As a result, a soft material can be obtained for the entire resin, and Tg in a temperature range lower than Tc can also be used, so that the third shape can be fixed. If a biodegradable resin is used for the main chain, the environmental load can be further reduced.

  Next, embodiments of the present invention will be described in detail.

  The mechanism of the shape memory resin of the present invention will be described in detail, but the following steps 1 to 6 give the first shape (memory), deformation processing (giving the second shape (memory)), deformation processing ( Application of the third shape), recovery of the second shape memory, recovery of the first shape memory and reshaping are realized. FIG. 3 shows a conceptual diagram.

1. Molding processing When the shape memory resin of the present invention is melted at a temperature (high temperature range) equal to or higher than the cleavage temperature (Td) of the thermoreversible cross-linked portion and molded into a predetermined shape, it is reversible with the stationary phase (thermo-reversible cross-linked portion). An initial state (original form) (phase (a)) consisting of phases (resin crystal phase: hard, resin amorphous phase: soft) is stored. Since the shape memory resin of the present invention becomes thermoplastic during molding, it is excellent in moldability.

2. Deformation processing (second shape)
In order to deform the molded product into an arbitrary shape, the reversible phase (heated to a temperature that softens only the reversible phase without cleaving the thermoreversible cross-linked portion of the stationary phase, that is, Tm of the resin to less than Td (medium temperature range) ( The resin can be transformed by applying an external force in this state (FIG. (C)). When the deformed molded product is cooled to Tc or less (normal temperature range), the reversible phase (only the crystal phase portion) is also completely solidified and fixed in a deformed state ((d) in the figure).

3. Deformation processing (third shape)
Further, since Tc (and Tm) is in a temperature range higher than Tg, the first shape obtained by the molding process is deformed, and the second shape fixed by crystallization is further deformed and cooled, whereby the third shape by Tg is obtained. The next state can be fixed. That is, the material has a two-stage shape memory property.

  The feature of this resin is that it can be deformed even at room temperature. That is, since the reversible phase in the normal temperature region has a soft amorphous layer, it can be further deformed ((e) in the figure). This deformation is fixed as a third shape by cooling to a temperature range (low temperature range) equal to or lower than Tg ((f) in the figure).

4). Recovery of second shape memory The third shape is kept in a deformed state by a reversible phase (crystalline phase and vitrified amorphous phase) that is temporarily forcedly fixed. Therefore, when the temperature reaches the temperature at which only the reversible phase vitrified amorphous phase is softened by heating (medium temperature range of Tg or more and less than Tm), a part of the resin exhibits a rubber-like characteristic and becomes a stable state. Restore shape (d).

5. Recovery of first shape memory The deformed state of the second shape is maintained by a reversible phase (crystal phase) that is temporarily forcedly fixed. Accordingly, when the temperature reaches a temperature at which the crystalline phase of the reversible phase is softened by heating (intermediate temperature range of Tm or more and less than Td), the resin further exhibits rubber-like characteristics and becomes a stable state, and recovers the original first shape (see FIG. b)). At this time, since the thermoreversible cross-linked portion of the stationary phase is a covalent cross-link, it is possible to achieve an excellent recovery force. Furthermore, it cools to less than Tc, and it fixes to the molded object of the initial state of the same figure (a).

6). Remolding Remolding involves heating to Td or higher of the thermoreversible cross-linked portion to cleave the cross-link, bringing the resin into a molten state, and re-molding it into the desired shape by the same method as described above. In the same figure (g), although the example which becomes a resin part and a crosslinking agent part by the cleavage of a thermoreversible crosslinking part is shown, resin parts can also be bridge | crosslinked directly, without using a crosslinking agent.

  An application example of the shape memory resin of the present invention is shown in FIG. In the shape memory resin of the present invention, the user can form the second shape (c or d; open state) of the arbitrary shape according to the use of the first shape (b: expanded state) of the split pin provided by the manufacturer. It is possible to grant. As a result, the split pin can quickly return to the original first state (b) and be easily pulled out only by heating to Tm or more and less than Td. Furthermore, when two-stage shape memory is possible, the user can temporarily fix an arbitrary third shape (e). For example, since the third shape is extended like the first shape and can be temporarily fixed by cooling to less than Tg, the pin can be easily inserted and the temperature is normal ( If it returns to Tg or more and less than Tm), it will become a 2nd shape (f: open state). This is convenient when the pin cannot be opened from the opposite side such as a closed container or wall as shown in (e). Furthermore, if it heats to Tm or more and less than Td, since it will return to a 1st state (b: extended state), it can disassemble easily. By heating to Td or higher, the resin can be melted and remolded.

  Tg is a phenomenon caused by freezing and melting of the molecular motion of the amorphous phase, and the elastic modulus of the resin increases in a temperature region below Tg, so that the deformed shape can be fixed. The increase in the elastic modulus of the crystalline resin depends on the ratio of the amorphous phase portion, but since Tg is in a temperature range lower than Tc (and Tm), when Tg type fixation is performed, the shape in the operating temperature range The memory resin becomes a hard resin by crystallization and vitrification. Therefore, it is preferable for applications that require high rigidity in the operating temperature range.

A conceptual diagram of the relationship of phase transition is shown in FIG.
For example, when a Diels-Alder reaction with a furan ring and a maleimide ring is used, the covalent thermoreversible reaction occurs at a binding temperature (Ta) of about 100 ° C. and a dissociation temperature of about 150 ° C. In contrast, when polybutylene succinate is used as the base resin for the main chain, the glass transition temperature (Tg) is about −30 ° C., the crystal melting temperature (Tm) is about 110 ° C., and the crystallization temperature (Tc). Is about 70 ° C. When the molten resin obtained at 150 ° C. or higher is cooled to 100 ° C. or lower, cross-linking by reversible cross-linking is formed, and a first shape is obtained.

  When this first shape is cooled to room temperature, it becomes Tc (70 ° C.) or lower, so that crystallization proceeds, but the first shape is maintained.

  Next, when heated again to Tm (110 ° C.) or higher and Td (150 ° C.) or lower, it becomes a rubbery and non-crystalline state and can be easily transformed into the second shape. , Crystallization occurs in a region below Tc (70 ° C.). Thereby, it becomes possible to fix the second shape in the normal temperature range. Since this second shape has a deformable flexibility, it can be further deformed into a third shape, and this third shape is cooled by cooling to less than Tg (−30 ° C.). Can be fixed.

  When this third shape is heated to Tg (−30 ° C.) or more and less than Tm (110 ° C.), it is restored to the second shape, and by heating to Tm (110 ° C.) or more and less than Td (150 ° C.), Restore to the first shape. Furthermore, it can be brought into a molten state by heating to Td (150 ° C.) or higher, and a different first shape can be obtained by cooling to Ta (100 ° C.) or lower.

  As for the resin, a resin having a Tm of less than Td of the thermoreversible reaction to be introduced and a temperature higher than the temperature that can be withstood when a molded body such as a member for electronic equipment is used is selected. Although the heat resistant temperature varies depending on the member to be used, the Tm of the resin is preferably 40 ° C. or higher and 200 ° C. or lower. Similarly, Tc is preferably 40 ° C. or higher and lower than 200 ° C. When Tm is less than 40 ° C., the rigidity at room temperature is low and the shape stability is poor, and when Tm is higher than 200 ° C., both the moldability and workability are poor and a large amount of energy is required. It is disadvantageous in terms of economy. The Tm of the resin is more preferably 40 ° C. or higher and 120 ° C. or lower. When a user memorizes the shape of a product, a dryer, hot water, or the like can be considered as a practical heating means. Especially when heating with hot water, the temperature can be controlled relatively accurately in a temperature range of 100 ° C. or lower, which is preferable. . On the other hand, when used for an outdoor use, Tm is preferably 60 ° C. or higher. Moreover, when using for the use where higher heat resistance is required, such as the interior for motor vehicles, Tm is preferably 80 ° C. or higher. In addition, when the Tm of the resin is equal to or higher than Td, the cross-linking is cleaved before the resin is softened, so that it is not possible to achieve shape memory excellent in shape memory. A resin having a Tm lower by 10 ° C. or more than the Td of the thermoreversible reaction to be introduced is preferable. In order to obtain a soft material that can be deformed into the third shape at room temperature, Tg is preferably 10 ° C. or lower. Also, Tg can be lowered to -190 ° C when liquid nitrogen is used. However, strict attention is required for handling liquid nitrogen, and versatility is poor. Therefore, in the present invention, it is desirable to use a Tg of −75 ° C. or higher so that it can be used at a temperature easily achieved by dry ice.

  The cleavage temperature (Td) of the thermoreversible reaction bond used for the cross-linked site is in the range of 50 ° C to 300 ° C. In the practical temperature range, the stationary phase and the reversible phase are not in a cured state, so that the mechanical properties usable for the electronic device member cannot be obtained. Therefore, when Td is less than 50 ° C., it is difficult to apply to electronic device members due to the problem of heat resistance. On the other hand, if Td exceeds 300 ° C., there is a problem in thermal decomposition of the resin and work, which is not appropriate.

  Next, Td is Tm + 10 ° C. or higher of the resin. During shape memory, the resin is deformed by heating at a temperature of Tm or higher to soften the reversible phase. However, if the stationary phase is not cross-linked at this temperature, the resin cannot be prevented from fluidity, and the shape cannot be memorized. . In order to widen the deformable temperature range, Td is desirably Tm + 20 ° C. or higher. More preferably, Td is desirably Tm + 30 ° C. or higher.

  Further, the temperature at the time of storing the second shape and at the time of recovering the first shape is set to a range of Tm or more and less than Td. If it is less than Tm, the crystalline phase of the resin does not melt, so that shape memory and recovery cannot be performed. Further, when Td or more, bond cleavage of the thermoreversible cross-linked structure occurs, so that the fluidity of the resin cannot be prevented, and the previously given memory is lost.

  And the temperature at the time of remolding shall be the range more than Td. Preferably, it is Td or more and less than the thermal decomposition start temperature of the resin. This is because bond cleavage of the thermoreversible reaction occurs at Td or higher, and the moldability of the resin is improved.

In summary, the following formula is obtained.
40 ° C ≦ Tm ≦ 200 ° C (1)
50 ° C. ≦ Td ≦ 300 ° C. (2)
Tm + 10 ° C. ≦ Td (3)
−75 ° C. ≦ Tg ≦ 10 ° C. (4)
40 ° C. ≦ Tm ≦ Tt <Td ≦ Tf <Tdec (5)
(In the above equation (5), Tt is the deformation temperature at the time of shape memory and shape recovery of the first shape, Tf is the molding and remolding temperature, and Tdec is the decomposition temperature of the resin.)

  The thermoreversible reaction can realize excellent shape memory property and recyclability as long as it includes one reaction type, but may include two or more reaction types. When two or more reaction types are included and each Td is different, assuming that the highest temperature Td is Td1 and the lowest temperature Td is Td2, the above equations (3) and (5) are as follows: .

Tm + 10 ° C ≦ Td2 (3 ')
Tm ≦ Tt <Td2 <Td1 ≦ Tf <Tdec (5 ′)

Also, when there is a temperature difference of 10 ° C. or more between two adjacent Td (Tda, Tdb), that is,
Tda + 10 ° C. ≦ Tdb (6)
If so, in addition to the shape memory at Tt, another shape can be stored. If the deformation temperature when performing another shape memory is Tt1, the following relationship is established.
Tt <Tda ≦ Tt1 <Tdb (7)

  In addition, when a polymer blend forms different cross-linked structures from each component to form a so-called interpenetrating network structure, a plurality of shapes can be stored.

  In the present invention, the preferred thermoreversible crosslinking reaction is one selected from the group consisting of Diels-Alder type, nitroso dimer type, acid anhydride ester type, urethane type, azlactone-hydroxyaryl type and carboxyl-alkenyloxy type. It is the above format.

(Introduction of resin functional groups)
The functional group necessary for the covalent thermoreversible reaction may be introduced into the molecular chain terminal of the resin material (precursor) subjected to thermoreversible crosslinking, or may be introduced into the molecular chain. Moreover, as an introduction method, an addition reaction, a condensation reaction, a copolymerization reaction, or the like can be used.

  For example, as a method for introducing a functional group into a molecular chain, various methods for introducing a functional group such as carboxylation or nitration of polystyrene are known. In addition, halogenation of polystyrene is also known, and it is possible to introduce necessary functional groups using various chemical reactions of halogen groups such as conversion to amine groups (Reference: Synthesis of polymers) -Reaction (3) p.13-Kyoritsu Shuppan Co., Ltd.).

  Resins having a functional group in the main chain can also be used. For example, a polymer having a hydroxyl group, such as polyvinyl alcohol, has been known to introduce a functional group such as esterification or etherification. In addition, a resin having a carboxylic acid group such as polymethacrylic acid can undergo various chemical reactions of carboxyl groups such as esterification. It is also effective to copolymerize these resins and resins having no functional group.

  As a method for introducing a functional group into the molecular chain terminal, for example, a functional group can be introduced using a terminal blocking agent during polymerization. For example, because the end of a living polymer such as styrene is a highly reactive carbanion, it reacts almost quantitatively with carbon dioxide, ethylene oxide, halogenated alkyl derivatives with functional groups protected by protecting groups, etc. It is possible to introduce a carboxylic acid group, a hydroxyl group, an amino group, a vinyl ether group, or the like. It is also possible to introduce a functional group at the end of the resin chain using a polymerization initiator having a functional group.

  In addition, introduction of a functional group by an esterification reaction is effective for polyester resins such as polyalkanoates. In addition to acid and alkali, esterification can be carried out using a reagent such as carbodiimide. It is also possible to esterify by reacting with a hydroxyl group after derivatizing the carboxyl group into an acid chloride using thionyl chloride or allyl chloride. In addition, for polyesters synthesized using dicarboxylic acid and diol as raw materials, all the terminal groups of the molecular chain can be converted to hydroxyl groups by increasing the molar ratio of diol / dicarboxylic acid of the raw material used to more than 1. Is possible.

  Moreover, it is possible to make a terminal into a hydroxyl group by transesterification. That is, the polyester resin having a terminal hydroxyl group is obtained by transesterifying the polyester resin with a compound having two or more hydroxyl groups.

  If a compound having three or more hydroxyl groups is used as the compound having a hydroxyl group, it is particularly desirable because a crosslinking point having a three-dimensional crosslinked structure can be formed. For example, by transesterifying the ester bond of hydroxyalkanoates such as polyhydroxybutyrolactone and polyhydroxyvalylate with pentaerythritol, a polyester having a total of four hydroxyl groups at the molecular chain ends can be obtained.

  Examples of the compound having two or more hydroxyl groups include dihydric alcohols such as ethylene glycol, propylene glycol, dipropylene glycol, 1,3- and 1,4-butanediol, 1,6-hexanediol, glycerin, triglyceride, and the like. Trivalent alcohols such as methylolpropane, trimethylolethane and hexanetriol, tetrahydric alcohols such as pentaerythritol, methylglycoside and diglycerin, polyglycerin such as triglycerin and tetraglycerin, and polypenta such as dipentaerythritol and tripentaerythritol Examples include erythritol, cycloalkane polyols such as tetrakis (hydroxymethyl) cyclohexanol, and polyvinyl alcohol. Examples thereof include sugar alcohols such as adonitol, arabitol, xylitol, sorbitol, mannitol, iditol, tallitol, dulcitol, and sugars such as glucose, mannose glucose, mannose, fructose, sorbose, sucrose, lactose, raffinose, and cellulose. Examples of the polyhydric phenol include monocyclic polyhydric phenols such as pyrogallol, hydroquinone and phloroglucin, bisphenols such as bisphenol A and bisphenol sulfone, and phenol / formaldehyde condensates (novolaks).

  Incidentally, a resin having a carboxylic acid at a terminal part or a compound having an unreacted hydroxyl group can be easily purified and removed.

  By performing an ester reaction with a hydroxybenzoic acid on the precursor and a precursor modified with a hydroxyl group, the hydroxyl group can be modified to a phenolic hydroxyl group.

  When a carboxyl group is required, it can be modified to a carboxyl group by bonding a compound having a bifunctional or higher carboxylic acid to the hydroxyl group by the above esterification reaction. In particular, when an acid anhydride is used, a precursor having a carboxyl group can be easily prepared. As the acid anhydride, pyromellitic anhydride, trimellitic anhydride, phthalic anhydride, hexahydrophthalic anhydride, maleic anhydride, and derivatives thereof can be used.

(Chemical structure of the crosslinking site)
The crosslinking site is composed of two first functional groups and second functional groups that are cleaved by heating and covalently bonded by cooling. When solidifying at a temperature lower than the melt processing temperature, the first functional group and the second functional group form a crosslink by a covalent bond, and at a predetermined temperature or higher such as the melt processing temperature, the first functional group and Cleave to the second functional group. The binding reaction and cleavage reaction at the cross-linked site proceed reversibly with temperature changes. The first functional group and the second functional group may be different functional groups or the same functional group. When the same two functional groups are bonded symmetrically to form a crosslink, the same functional group can be used as the first functional group and the second functional group.

(1) Diels-Alder type reaction Diels-Alder [4 + 2] cyclization reaction is utilized. By introducing conjugated diene and dienophile as functional groups, a shape memory resin crosslinked by a thermoreversible reaction is obtained. Examples of the conjugated diene include a furan ring, a thiophene ring, a pyrrole ring, a cyclopentadiene ring, 1,3-butadiene, a thiophene-1-oxide ring, a thiophene-1,1-dioxide ring, and a cyclopenta-2,4-dienone. Ring, 2H pyran ring, cyclohexa-1,3-diene ring, 2H pyran 1-oxide ring, 1,2-dihydropyridine ring, 2H thiopyran-1,1-dioxide ring, cyclohexa-2,4-dienone ring, pyran A 2-one ring and a substituted product thereof are used as a functional group. As the dienophile, an unsaturated compound that additionally reacts with a conjugated diene to give a cyclic compound is used. For example, a vinyl group, an acetylene group, an allyl group, a diazo group, a nitro group, or a substituted product thereof is used as a functional group. The conjugated diene may also act as a dienophile.

  Among these, for example, cyclopentadiene can be used for the crosslinking reaction, and Td is 150 ° C. or higher and 250 ° C. or lower. Dicyclopentadiene has both conjugated diene and dienophile effects. Dicyclopentadiene dicarboxylic acid, which is a dimer of cyclopentadiene carboxylic acid, can be easily obtained from commercially available sodium cyclopentadienyl (reference: E. Ruksenstein et al., J. Polym. Sci. Part A: Polym. Chem., 38, 818-825, 2000). This dicyclopentadiene dicarboxylic acid is introduced into a site having a hydroxyl group by a esterification reaction into a precursor having a hydroxyl group, a precursor modified with a hydroxyl group, or the like.

  For example, when 3-maleimidopropionic acid and 3-furylpropionic acid are used, a thermoreversible reaction with Td of 80 ° C. is obtained. A crosslinking site can be easily introduced into a site where a hydroxyl group exists in a precursor having a hydroxyl group, a precursor modified with a hydroxyl group, or the like by an esterification reaction.

  For the esterification reaction used for the introduction of the crosslinking site, a catalyst such as carbodiimide can be used in addition to the acid and alkali. It is also possible to esterify by reacting with a hydroxyl group after derivatizing a carboxyl group into an acid chloride using thionyl chloride or allyl chloride. If an acid chloride is used, it easily reacts with an amino group, so that it can be introduced into the amino group side of amino acids and derivatives thereof.

  A maleimide derivative which is a dienophile can be synthesized from a polyamine having at least two amino groups in one molecule. For example, trimethylenediamine, tetramethylenediamine, hexamethylenediamine, xylylenediamine, 3,9-bis (3-aminopropyl) -2,4,8,10-tetraoxaspiro [5.5] undecane, bis ( Aliphatic amines such as 4-aminocyclohexyl) methane and tris (2-aminoethyl) amine, m-phenylenediamine, p-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylsulfone, 4, 4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 2,2-bis- (4-aminophenyl) propane, bis- (4-aminophenyl) diphenylsilane Bis- (4-aminophenyl) methylphosphine oxide Bis- (3-aminophenyl) methylphosphine oxide, bis- (4-aminophenyl) -phenylphosphine oxide, bis- (4-aminophenyl) pheniramine, 1,5-diaminonaphthalene, 2,4-diaminotoluene, 2,6-diaminotoluene, 3,3′-dimethyl-4,4′-diaminophenylmethane, 2,2′-dimethyl-4,4′-diaminophenylmethane, 3,3 ′ · 5,5′-tetra Methyl-4,4′-diaminodiphenylmethane, 3,3′-diethyl-4,4′-diaminodiphenylmethane, 3,3 ′ · 5,5′-tetraethyl-4,4′-diaminophenylmethane, 3,3 ′ -Di-n-butyl-4,4'-diaminodiphenylmethane, 3,3'-di-tert-butyl-4,4'-diaminodiphenyl Tan, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, bis [4- (4-aminophenoxy) phenyl] sulfone, bis (3-chloro-4-aminophenyl) methane, triaminobenzene , Triaminotoluene, triaminonaphthalene, triaminodiphenyl, triaminopyridine, triaminophenyl ether, triaminodiphenylmethane, triaminodiphenyl sulfone, triaminobenzophenone, triaminophenyl orthophosphate, tri (aminophenyl) phosphine oxide, tetra Aminobenzophenone, tetraaminobenzene, tetraaminonaphthalene, diaminobenzidine, tetraaminophenyl ether, tetraaminophenylmethane, tetraaminophenylsulfone, bis (diaminophen Nil) aromatic amines such as pyridine and melamine, aromatic polyamines obtained by condensation reaction of aniline and formaldehyde, tetrafunctional aromatic polyamines which are reaction products of aromatic dialdehydes and aromatic amines, aromatic Aromatic polyamines obtained from mixtures of dialdehyde and formaldehyde and aromatic amines, polymers of vinylanilines, aliphatic polyamines such as polyallylamine, polylysine, polyortinin, polyethyleneimine, polyvinylamine, chitin, chitosan, etc. Aminopolysaccharides are mentioned. Naturally derived amino compounds are preferred as resin materials from the viewpoint of environmental problems.

  The Diels-Alder type reaction between these functional groups, for example, cyclopentadienyl groups, forms a thermoreversible crosslinked structure as shown in the following general reaction formula (I).

(2) Nitroso dimer type reaction In the general reaction formula (II), two nitroso groups form a nitroso dimer upon cooling to form a bridge. The Td of this cross-linking is 110 ° C. to 150 ° C.

  For example, a dimer of 4-nitroso-3,5-benzylic acid (Reference: US Pat. No. 3,872,057 discloses a method for synthesizing a dimer of 4-nitroso-3,5-dichlorobenzoyl chloride. Can be easily thermoreversible at the site where the hydroxyl group is present by reacting with the hydroxyl group of the precursor having a hydroxyl group, the hydroxyl group of a precursor modified with a hydroxyl group, etc. Cross-linking sites can be introduced. In addition, when acid chlorides are used, they can be easily introduced into the amino group side of amino acids and derivatives thereof because they easily react with amino groups.

  The dimerization reaction of the nitroso group forms a thermoreversible crosslinked structure as shown in the following general reaction formula (II).

(3) Acid anhydride ester type reaction (reaction of acid anhydride group and hydroxyl group)
Acid anhydrides and hydroxyl groups can be used for the crosslinking reaction. As the acid anhydride, aliphatic carboxylic anhydride and aromatic carboxylic anhydride are used. Moreover, although both a cyclic acid anhydride group and a non-cyclic anhydride group can be used, a cyclic acid anhydride group is used suitably. Examples of the cyclic acid anhydride group include a maleic anhydride group, a phthalic anhydride group, a succinic anhydride group, and a glutaric anhydride group. Examples of the acyclic acid anhydride group include an acetic anhydride group and a propionic anhydride group. And benzoic anhydride groups. Among them, maleic anhydride group, phthalic anhydride group, succinic anhydride group, glutaric anhydride group, pyromellitic anhydride group, trimellitic anhydride group, hexahydrophthalic anhydride group, acetic anhydride group, propionic anhydride group, anhydrous A benzoic acid group and a substituted product thereof are preferable as an acid anhydride that reacts with a hydroxyl group to form a crosslinked structure.

  As the hydroxyl group, a hydroxyl group such as a hydroxyl group of a precursor having a hydroxyl group or a precursor into which a hydroxyl group has been introduced by various reactions is used. Moreover, you may use hydroxy compounds, such as diol and a polyol, as a crosslinking agent. Furthermore, diamines and polyamines can also be used as crosslinking agents. For example, if an acid anhydride having two or more acid anhydrides such as pyromellitic anhydride is used, it can be used as a crosslinking agent for a precursor having a hydroxyl group, a precursor modified with a hydroxyl group, etc. .

  Further, a compound having two or more maleic anhydrides can be easily obtained by copolymerizing maleic anhydride with an unsaturated compound by vinyl polymerization (reference: JP-A-11-106578 (Patent Document 8), No. 2000-34376). This can also be used as a crosslinking agent for precursors having hydroxyl groups, precursors modified with hydroxyl groups, and the like.

  The acid anhydride and hydroxyl group as described above form a thermoreversible cross-linked structure as shown in the following general reaction formula (III). In the general reaction formula (III), an acid anhydride group and a hydroxyl group form an ester upon cooling to form a crosslink. The Td of this crosslinking is 260 ° C.

(4) Urethane type reaction (reaction of isocyanate group and active hydrogen)
A thermoreversible crosslinking site can be formed from isocyanate and active hydrogen. For example, polyisocyanate is used as a crosslinking agent and reacts with the hydroxyl group, amino group, and phenolic hydroxyl group of the precursor and its derivatives. In addition, a molecule having two or more functional groups selected from a hydroxyl group, an amino group and a phenolic hydroxyl group can be added as a crosslinking agent. Further, a catalyst can be added to bring the cleavage temperature into a desired range. Moreover, dihydroxybenzene, dihydroxybiphenyl, a phenol resin, etc. can also be added as a crosslinking agent.

  In addition, polyisocyanate is used as a crosslinking agent and reacted with the hydroxyl group, amino group, and phenolic hydroxyl group of the precursor and its derivative. Dihydroxybenzene, dihydroxybiphenyl, phenol resin and the like can be added as a crosslinking agent. Examples of the polyvalent isocyanate include tolylene diisocyanate (TDI) and a polymer thereof, 4,4′-diphenylmethane isocyanate (MDI), hexamethylene diisocyanate (HMDI), 1,4-phenylene diisocyanate (DPDI), 1,3- Phenylene diisocyanate, xylylene diisocyanate, lysine diisocyanate, 1-methylbenzene-2,4,6-triisocyanate, naphthalene-1,3,7-triisocyanate, biphenyl-2,4,4'-triisocyanate, triphenylmethane -4,4 ', 4 "-triisocyanate, tolylene diisocyanate, lysine triisocyanate and the like can be used.

  In order to adjust the cleavage temperature, organic compounds such as 1,3-diacetoxytetrabutyl distanoxane, amines, metal soaps and the like may be used as the cleavage catalyst.

  The urethanization reaction with the above functional group forms a thermoreversible crosslinked structure as shown in the following general reaction formula (IV). In the general reaction formula (IV), the phenolic hydroxyl group and the isocyanate group form urethane by cooling to be crosslinked. Td of this crosslinking is 120 ° C. or more and 250 ° C. or less, and can be adjusted by a catalyst.

(5) Azlactone-hydroxyaryl type reaction (reaction of azlactone group and phenolic hydroxyl group)
Examples of the aryl group include a phenyl group, a tolyl group, a xylyl group, a biphenyl group, a naphthyl group, an anthryl group, a phenanthryl group, and a group derived from these groups, and a phenolic hydroxyl group bonded to these groups. Reacts with the azlactone structure contained in the group forming the crosslinked structure. As the compound having a phenolic hydroxyl group, a precursor having a phenolic hydroxyl group, a precursor modified with hydroxylphenols, or the like is used.

  As the azlactone structure, 1,4- (4,4′-dimethylazulactyl) butane, poly (2-vinyl-4,4′-dimethylazalactone), bisazulactone benzene, bisazlactone hexane and the like Azlactone is preferred.

  Moreover, bisazulactyl butane etc. of azlactone-phenol reaction bridge | crosslinking can also be used, These are described in the said nonpatent literature 1, for example.

  These functional groups form a thermoreversible crosslinked structure as shown in the following general reaction formula (V). In the general reaction formula (V), the azlactone group and the phenolic hydroxyl group form a covalent bond by cooling to form a crosslink. Td of this crosslinking is 100 ° C. or more and 200 ° C. or less.

(6) Carboxyl-alkenyloxy reaction As those having a carboxyl group, a precursor having a carboxyl group, a precursor modified with a carboxyl group, and the like are used. Examples of the alkenyloxy structure include vinyl ethers, allyl ethers, and structures derived from these structures, and those having two or more alkenyloxy structures can also be used.

  Alkenyl ether derivatives such as bis [4- (vinyloxy) butyl] adipate and bis [4- (vinyloxy) butyl] succinate can also be used as a crosslinking agent.

  These functional groups form a thermoreversible crosslinked structure as shown in the following general reaction formula (VI). In the general reaction formula (VI), a carboxyl group and a vinyl ether group form a hemiacetal ester by cooling to form a crosslink (reference: JP-A-11-35675 (Patent Document 7), JP-A-60-179479). Issue gazette). The Td of this crosslinking is 100 ° C. or more and 250 ° C. or less, and can be adjusted by the crosslinked structure.

(Crosslinking agent)
As explained above, a compound having in the molecule two or more functional groups capable of forming a thermoreversible crosslinking site can serve as a crosslinking agent.

  Examples of the crosslinking agent having an acid anhydride group include a bisphthalic anhydride compound, a bissuccinic anhydride compound, a bisglutaric anhydride compound, a bismaleic anhydride compound, and substituted products thereof.

  Examples of the crosslinking agent having a hydroxyl group include dihydric alcohols such as ethylene glycol, propylene glycol, dipropylene glycol, 1,3- and 1,4-butanediol, and 1,6-hexanediol, glycerin, trimethylolpropane, Trivalent alcohols such as trimethylolethane and hexanetriol, tetrahydric alcohols such as pentaerythritol, methylglycoside and diglycerin, polyglycerins such as triglycerin and tetraglycerin, polypentaerythritol such as dipentaerythritol and tripentaerythritol, tetrakis Examples include cycloalkane polyols such as (hydroxymethyl) cyclohexanol, and polyvinyl alcohol. Examples thereof include sugar alcohols such as adonitol, arabitol, xylitol, sorbitol, mannitol, iditol, tallitol, dulcitol, and sugars such as glucose, mannose glucose, mannose, fructose, sorbose, sucrose, lactose, raffinose, and cellulose.

  Examples of the crosslinking agent having a carboxyl group include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, phthalic acid, maleic acid, and fumaric acid.

  Examples of the crosslinking agent having a vinyl ether group include bis [4- (vinyloxy) butyl] adipate, bis [4- (vinyloxy) butyl] succinate, ethylene glycol divinyl ether, butanediol divinyl ether, 2,2-bis [p -(2-vinyloxyethoxy) phenyl] propane, tris [4- (vinyloxy) butyl] trimellitate.

  Examples of the crosslinking agent having a phenolic hydroxyl group include monocyclic polyphenols such as dihydroxybenzene, pyrogallol, and phloroglucin, bisphenols such as dihydroxybiphenyl, bisphenol A, and bisphenol sulfone, resol type phenol resins, and novolac type phenol resins. It is done.

  Examples of the cross-linking agent having an isocyanate group include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, p. -Aromatic diisocyanates such as phenylene diisocyanate, aliphatic diisocyanates such as hexamethylene diisocyanate and lysine diisocyanate, alicyclic diisocyanates such as isophorone diisocyanate, and aryl aliphatic diisocyanates such as xylylene diisocyanate. Examples of trifunctional isocyanates include 1-methylbenzene-2,4,6-triisocyanate, naphthalene-1,3,7-triisocyanate, biphenyl-2,4,4′-triisocyanate, triphenylmethane. -4,4 ', 4 "-triisocyanate, trimer of tolylene diisocyanate, lysine triisocyanate and the like.

  Examples of the crosslinking agent having an azlactone group include bisazulactone butane, bisazulactone benzene, and bisazulactone hexane.

  Examples of the crosslinking agent having a nitroso group include dinitrosopropane, dinitrosohexane, dinitrosobenzene, and dinitrosotoluene.

(Selection of cross-linked structure)
As described above, the reversible reaction forms by bonding by cooling to form a crosslinking site and cleavage by heating, as described above, Diels-Alder type, nitroso dimer type, acid anhydride ester type, urethane type, azlactone-hydroxy Aryl and carboxyl-alkenyloxy types can be used.

  However, there are cases where it is better to avoid deterioration of the main chain due to thermal decomposition or hydrolysis resin, or chemical reaction in which the crosslinking site is deactivated by side reaction. For example, polyester resins such as polylactic acid and polycarbonate are not suitable for acid anhydride ester type crosslinking because hydrolysis occurs by carboxylic acid. A resin having a large number of hydroxyl groups such as polyvinyl alcohol is not suitable because it causes a curing reaction with urethane type, azlactone-hydroxyaryl type and carboxyl-alkenyloxy type. On the other hand, since the Diels-Alder type is hydrophobic, it can be applied to a resin that is easily hydrolyzed, and the reactive group is not deactivated by moisture or the like, so that it can be applied to various resins. It can also be suitably used for plant-derived resins having many ester bonds.

(resin)
(Plant-derived resin material)
As the resin of the cross-linked product, a resin material that is a plant-derived raw material is selected in consideration of the nature of the functional group introduced to form a thermoreversible cross-linked structure.

  Such plant-derived resin materials include monomers, oligomers and polymers that can be artificially synthesized from biomass raw materials; monomer derivatives that can be synthesized from biomass raw materials, modified oligomers and modified polymers; Monomers, oligomers and polymers that are available and available; derivatives of monomers that are synthesized and available mainly in nature, modified oligomers, modified polymers, etc. are mainly used.

Examples of the artificially synthesized oligomer and polymer include polylactic acid (manufactured by Shimadzu Corporation, trade name: Lacty, etc.), polyalphahydroxy acid such as polyglycolic acid, polyomegahydroxyalkanoate such as polyepsilon caprolactone (manufactured by Daicel Corporation, product) Name: Plaxel, etc.), polyalkylene alkanoates which are polymers of butylene succinate, polyesters such as polybutylene succinate, polyamino acids such as poly-γ-glutamate (manufactured by Ajinomoto Co., Inc., trade name: polyglutamic acid, etc.) And so on.
In addition, modified products of these artificially synthesized oligomers and polymers can be suitably used.

Naturally synthesized oligomers and polymers include starch, amylose, cellulose, cellulose ester, chitin, chitosan, gellan gum, carboxyl group-containing cellulose, carboxyl group-containing starch, pectic acid, alginic acid and other polysaccharides; hydroxy synthesized by microorganisms Polybetahydroxyalkanoate which is a polymer of butyrate and / or hydroxyvalerate (manufactured by Zeneca, trade name: Biopol, etc.) can be mentioned, among others, starch, amylose, cellulose, cellulose ester, chitin, Chitosan, hydroxybutyrate synthesized by microorganisms and / or polybetahydroxyhydroxyalkanoate which is a polymer of hydroxyvalerate are preferred.
Naturally modified oligomers and modified polymers can also be suitably used.

  Furthermore, lignin etc. can be used as a modified body of natural synthetic oligomer and polymer. Lignin is a biodegradable dehydrogenated polymer of coniferyl alcohol and sinapyr alcohol contained in wood by 20-30%.

  Among the biodegradable resin materials as described above, artificial synthetic biodegradable oligomers and polymers, modified artificial biodegradable oligomers and polymers, natural synthetic biodegradable oligomers and modified polymers are intermolecular bonds. Since the force is moderate, it is excellent in thermoplasticity, the viscosity at the time of melting does not increase remarkably, and it is preferable because it has good moldability.

  Of these, polyesters and modified products of polyesters are preferable, and aliphatic polyesters and modified products of aliphatic polyesters are more preferable. Polyamino acids and modified products of polyamino acids are preferable, and aliphatic polyamino acids and modified products of aliphatic polyamino acids are more preferable. Also, polyols and modified products of polyols are preferable, and aliphatic polyols and modified products of aliphatic polyols are more preferable.

  Of the above plant-derived resin materials, those having a Tm of 40 ° C. ≦ Tm ≦ 200 ° C. and a Tg of −70 ° C. ≦ Tg ≦ 10 ° C. can be used. For example, polybutylene succinate can be preferably used because Tm is about 110 ° C. and Tg is around −30 ° C. Also, poly-4-hydroxybutanate (Tg; about −34 ° C., Tm; about 52 ° C.), poly-5-hydroxyvalerate (Tg; about −40 ° C., Tm; about 57 ° C.), poly-3- Polyhydroxyalkanoates such as hydroxypropylate (Tg; about −25 ° C., Tm; about 102 ° C.) can also be suitably used.

  Furthermore, since the final resin composition Tg and Tm only need to be within the above temperature range, an alloy or copolymer is formed based on two or more kinds of resins selected from the above plant-derived resins. It is also possible to use this. For example, starch may be added to polybutylene succinate or polyhydroxyalkanoate (Tg and Tm are not changed).

  Even if the Tm alone is less than 40 ° C. or the Tg is 10 ° C. or more, the Tm and Tg can be adjusted by copolymerization or blending with a resin having a high Tm or a resin having a low Tg. Is possible.

  In addition, the degree of crystallinity can be adjusted by the crosslinked structure of the resin. For example, by reducing the molecular weight of the precursor or increasing the number of functional groups of the precursor, the crosslinking density can be increased and the crystallinity of the resin can be lowered. By increasing the molecular weight of the precursor or reducing the number of functional groups of the precursor, the crosslinking density can be lowered and the crystallinity of the resin can be increased. By reducing the degree of crystallinity, the elastic modulus can be lowered and the second shape can be easily deformed and adjusted. Further, Tg is increased by increasing the degree of crosslinking, and Tg is decreased by decreasing the degree of crosslinking. Therefore, it is possible to adjust Tg.

  However, based on the plant-derived resin material described above, the number average molecular weight of the crosslinked resin precursor thus derived is within the following range, but the second shape is fixed due to excessive decrease in crystallinity. If it becomes impossible, the plant resin material or resin material mixture cannot be used.

  The number average molecular weight (hereinafter abbreviated as molecular weight) of the precursor is used in the range of 500 to 100,000. Preferably, it is 1,000-10,000. If the molecular weight of the precursor is less than 500, the mechanical properties and processability of the resin may be inferior. In addition, if it exceeds 100,000, the crosslink density becomes low, so the shape memory property of the first shape may be inferior. However, by using a branched structure to increase the crosslink density, a higher molecular weight precursor should be used. Is also possible.

  It is necessary to use one or more kinds of precursors. One or more cross-linked bodies can be used. In order to obtain a three-dimensional cross-linked structure, at least one of the precursor or the cross-linked product needs to have three or more cross-linked sites.

Further, the ratio (G ′ {Tm} / G ′ {Tm + 20 ° C.}) of the storage rigidity G ′ (Pa) at temperatures above and below Tm and the ratio (G ′ of the storage rigidity G ′ (Pa) at temperatures above and below Tg. {Tg} / G ′ {Tg + 20 ° C.} are both 1.0 × 10 ¹ or more, preferably 2.0 × 10 ¹ or more, and (G ′ {Tg} / G ′ {Tm + 20 ° C.}) is 1. A cross-linked product in a range of 0.0 × 10 ⁷ or less, preferably 1.0 × 10 ⁵ or less is used. G ′ decreases with the activation of the micro-Brownian motion of the amorphous phase at temperatures above Tg, and the micro-Brownian motion associated with melting of the crystal phase at temperatures above Tm, so Tg and Tm (or G ′ at the upper and lower temperatures) The ratio of (G ′ {Tm} / G ′ {Tm + 20 ° C.}) and (G ′ {Tg} / G ′ {Tg + 20 ° C.}) is less than 1.0 × 10 ^1. However, even if the temperature is higher than Tg, it does not exhibit sufficient rubber properties and is difficult to deform.However, even when the network structure is insufficient to memorize the shape, such as when the crosslinking density is excessively reduced, the thermoplasticity As with the resin, the elastic modulus at Tm or more is greatly reduced and the shape memory property is lost, so (G ′ {Tg} / G ′ {Tm + 20 ° C.}) is 1.0 × 10 ⁷ or less. Is preferred.

  In obtaining the shape memory resin of the present invention, an inorganic filler, an organic filler, a reinforcing material, a colorant, a stabilizer (such as a radical scavenger and an antioxidant), an antibacterial agent, and the like, as long as desired properties are not impaired. An antifungal material, a flame retardant, etc. can be used together as needed. As the inorganic filler, silica, alumina, talc, sand, clay, slag and the like can be used. As the organic filler, organic fibers such as polyamide fibers and plant fibers can be used. As the reinforcing material, glass fiber, carbon fiber, polyamide fiber, polyarylate fiber, acicular inorganic material, fibrous fluororesin, or the like can be used. As the antibacterial agent, silver ions, copper ions, zeolites containing these, and the like can be used. As the flame retardant, silicone flame retardant, bromine flame retardant, phosphorus flame retardant, inorganic flame retardant and the like can be used.

  Resins and resin compositions such as those described above can be used for electrical and electronic equipment such as casings of electrical appliances by general thermoplastic resin molding methods such as injection molding, film molding, blow molding, and foam molding. It can be processed into various forms such as uses.

  The present invention will be described in more detail with reference to the following examples, but these examples do not limit the present invention. Unless otherwise specified, commercially available high-purity products were used as reagents. The number average molecular weight was measured by a gel permeation chromatogram method and converted using standard polystyrene. The performance was evaluated by the following method.

    Crystallization temperature (Tc), glass transition temperature (Tg), crystal melting temperature (Tm), cleavage temperature (Td): melting temperature (high temperature) using a DSC measuring device (trade name: DSC6000) manufactured by Seiko Instruments Inc. The temperature was measured at a temperature drop rate of 10 ° C./min. Subsequently, measurement was performed at a temperature increase rate of 10 ° C./min (from a low temperature range) to determine Tg, Tm, and Td. (See Figure 5 for a conceptual diagram)

    Shape memory: Create a 2cm x 5cm x 1.0mm molded body (first shape), heat at Tm + 20 ° C, fold the center of the molded body to 30 °, deform for 5 seconds, and then cool to room temperature A second shape was obtained. Evaluation was made at the angle (A1) of the molded body at this time. 20 ° ≦ A1 ≦ 30 ° was evaluated as “◯”, 10 ° ≦ A1 <20 ° as “Δ”, and 0 ° ≦ A1 <10 ° as “×”. Next, the deformed molded body was bent in the opposite direction (−30 °), deformed for 5 seconds, and then cooled to a temperature equal to or lower than Tg to obtain a third shape. The deformability of the film at this time was evaluated by the angle (A2). −20 ° ≦ A2 ≦ −30 ° was evaluated as “◯”, −10 ° ≦ A2 <−20 ° as Δ, and 0 ° ≦ A2 <−10 ° as “×”. It heated again to normal temperature (Tg or more and less than Tm), and recoverability was evaluated by angle (A3). 0 ° <A3 ≦ 10 ° was taken as x, 10 ° <A3 ≦ 20 ° was taken as Δ, and 20 ° ≦ A3 ≦ 30 ° was taken as ○. Further, the molded body was heated at Tm + 20 ° C. for 60 seconds, and the recoverability was evaluated by the angle (A4). 20 ° <A4 ≦ 30 ° was evaluated as x, 10 ° <A4 ≦ 20 ° as Δ, and 0 ° ≦ A4 ≦ 10 ° as ○.

    Remoldability: The molded body was heated at 200 ° C., and molding was attempted again. However, Comparative Example 3 was heated to 250 ° C. Those that could not be melted were marked with ×, and those that were melted were marked with ○. However, even if melted, those that did not show the same shape memory characteristics as before re-molding were also marked as x.

  Examples of polybutylene succinate as a precursor are shown below. Since polybutylene succinate has biodegradability and can be synthesized as a plant-derived material, it is a preferable material from the viewpoint of environmental problems. Further, the crystal melting temperature (Tm) is around 110 ° C., and it can be easily melted. Since the crystallization temperature (Tc) is in the range of around 70 ° C. and higher than the normal temperature range, the second shape can be easily retained. Furthermore, since the glass transition temperature (Tg) is around −30 ° C., the third shape can be easily fixed. In order to impart excellent shape memory and recyclability to polybutylene succinate, the following materials were designed. First, since the thermal decomposition of polybutylene succinate occurs at 200 ° C. or higher, a reversible crosslinking site having a dissociation temperature (Td) of 120 ° C. or higher and 200 ° C. or lower was selected. As this reversible reaction, Diels-Alder type, carboxyl-alkenyloxy type, urethane type and the like can be used. Next, a reversible crosslinking site was introduced into the polybutylene succinate, and three-dimensional crosslinking was performed. Finally, we verified the shape memory and recyclability of the crosslinked resin.

  Hereinafter, examples in which a Diels-Alder type furan-maleimide bond is introduced into polybutylene succinate are shown. The dissociation temperature of the furan-maleimide bond is described as 80 ° C. or 140 ° C. in the literature (Non-patent Document 2). As shown in the following examples, the dissociation temperature is 150 ° C., and the polybutylene succinate base is used. It becomes a suitable crosslinking site for the resin.

[Example 1]
100 g of 2-furfuryl alcohol, 112 g of succinic anhydride and 2 ml of pyridine were dissolved in 1 L of chloroform and refluxed for 10 hours. After washing this with water, the solvent was distilled off to synthesize furan derivative [F1].

  A 1 L separable flask equipped with a stirrer, a shunt condenser, a thermometer, and a nitrogen introduction tube was charged with 118 g (1.0 mol) of succinic acid and 95 g (1.05 mol) of 1,4-butanediol under a nitrogen atmosphere. Dehydration condensation was performed at 180 to 220 ° C. for 1 hour. Subsequently, both terminal hydroxyl group aliphatic polyester (R1) having a number average molecular weight of 510 was obtained by reprecipitation with chloroform and methanol.

  To 500 ml of chloroform, 21.1 g (0.11 mol) of 1-ethyl-3- (3′-dimethylaminopropyl) carbodiimide hydrochloride (WSC), 8.7 g (0.11 mol) of pyridine, [F1] 21. 8 g (0.11 mol) and 25.5 g (0.05 mol) of (R1) were added and refluxed for 10 hours. This was washed with water, dried over magnesium sulfate, and reprecipitated with methanol to obtain furan-modified polybutylene succinate [R2] (molecular weight 900).

  Exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride dissolved in 250 ml of DMF after heating 25 ml of tris (2-aminoethyl) amine dissolved in 100 ml of dimethylformamide (DMF) 100 g was added dropwise over 1 hour and stirred for 2 hours. Further, 200 ml of acetic anhydride, 10 ml of triethylamine and 1 g of nickel acetate were added and stirred for 3 hours. After stirring, 1000 ml of water was added, the solvent was heated under reduced pressure at 60 ° C., dissolved in chloroform, and washed with water. Chloroform was distilled off under reduced pressure and purified by silica gel chromatography. Further, after refluxing with toluene under nitrogen for 24 hours, trifunctional maleimide [R3] (molecular weight 386) was obtained by recrystallization.

  Next, (R2) 27 g (0.03 mol) and (R3) 7.7 g (0.02 mol) were melt-mixed at 150 ° C., poured into a mold, and then subjected to a crosslinking reaction at 100 ° C. for 1 hour. A molded product was obtained.

[Example 2]
A 1 L separable flask equipped with a stirrer, a shunt condenser, a thermometer, and a nitrogen introduction tube was charged with 118 g (1.0 mol) of succinic acid and 95 g (1.05 mol) of 1,4-butanediol under a nitrogen atmosphere. Dehydration condensation was performed at 180 to 220 ° C. for 7 hours. Subsequently, a deglycolization reaction was performed at 180 to 220 ° C. under reduced pressure for 0.5 hour, and a hydroxyl group aliphatic polyester (R4) having a number average molecular weight of 1600 was obtained by reprecipitation with chloroform and methanol.

  To 500 ml of chloroform, 12.65 g (0.066 mol) of 1-ethyl-3- (3′-dimethylaminopropyl) carbodiimide hydrochloride (WSC), 5.21 g (0.066 mol) of pyridine, [F1] 13. 08 g (0.066 mol) and 48 g (0.03 mol) of (R4) were added and refluxed for 10 hours. This was washed with water, dried over magnesium sulfate, and reprecipitated with methanol to obtain furan-modified polybutylene succinate [R5] (molecular weight 2000).

  Next, (R5) 18.0 g (0.009 mol) and (R3) 2.32 g (0.006 mol) were melt-mixed at 150 ° C., poured into a mold, and then crosslinked at 100 ° C. for 1 hour. To obtain a molded product.

[Example 3]
A 1 L separable flask equipped with a stirrer, a shunt condenser, a thermometer, and a nitrogen introduction tube was charged with 118 g (1.0 mol) of succinic acid and 108 g (1.2 mol) of 1,4-butanediol under a nitrogen atmosphere. Dehydration condensation was performed at 180 to 220 ° C. for 4 hours. Subsequently, a deglycolization reaction was performed at 180 to 220 ° C. under reduced pressure for 13 hours, and water and vinyl glycol were distilled off to obtain a hydroxyl group aliphatic polyester (R6) having a number average molecular weight of 10,600.

  To 500 ml of chloroform, 1.05 g (0.0055 mol) of 1-ethyl-3- (3′-dimethylaminopropyl) carbodiimide hydrochloride (WSC), 0.434 g (0.0055 mol) of pyridine, [F1] 09 g (0.0055 mol) and 53 g (0.005 mol) of (R5) were added and refluxed for 10 hours. This was washed with water, dried over magnesium sulfate, and reprecipitated with methanol to obtain furan-modified polybutylene succinate [R7] (molecular weight 10,100).

  Next, 30 g (0.003 mol) of (R7) and 0.77 g (0.002 mol) of (R3) were melt mixed at 150 ° C., poured into a mold, and then subjected to a crosslinking reaction at 100 ° C. for 1 hour. A molded product was obtained.

[Comparative Example 1]
Melting 0.534 g (0.002 mol) of lysine triisocyanate (Kyowa Hakko Chemical Co., Ltd.) at 150 ° C. into 32 g (0.003 mol) of hydroxyl group aliphatic polyester (R6) having a number average molecular weight of 10,600. After mixing and pouring into a mold, a crosslinking reaction was performed at 150 ° C. for 1 hour to obtain a molded product.

[Comparative Example 2]
Commercially available PBS (Showa Polymer # 1020) was heated, melted and cooled to 200 ° C. in a mold to produce a molded product for evaluation.

[Comparative Example 3]
A commercially available thermoplastic shape memory resin (“Diaplex” (trade name), manufactured by Mitsubishi Heavy Industries, Ltd.) was heated, melted and cooled to 200 ° C. in a mold to produce a molded product for evaluation. .

[Comparative Example 4]
A molded product for evaluation was manufactured using a commercially available thermosetting shape memory resin (“Kuraprene HM sheet” (trade name), manufactured by Kuraray Co., Ltd.).

[Comparative Example 5]
To 500 ml of chloroform, 42.17 g (0.22 mol) of 1-ethyl-3- (3′-dimethylaminopropyl) carbodiimide hydrochloride (WSC), 17.4 g (0.22 mol) of pyridine, [F1] 43. 6 g (0.22 mol) and 90.1 g (0.1 mol) of 1,4-butanediol were added and refluxed for 10 hours. This was washed with water, dried over magnesium sulfate, and the solvent was distilled off to obtain furan-modified polybutylene succinate [R8] (molecular weight 500).

  Next, (R8) 14.0 g (0.03 mol) and (R3) 7.7 g (0.02 mol) were melt-mixed at 150 ° C., poured into a mold, and then subjected to a crosslinking reaction at 100 ° C. for 1 hour. To obtain a molded product.

[Shape memory]
The above 8 examples were evaluated for shape memory property, shape recoverability, and remoldability. (Table 1)

  As apparent from Table 1, except for Comparative Examples 3 and 5, −75 ° C. ≦ Tg ≦ 10 ° C. and 40 ° C. ≦ Tm ≦ 200 ° C. are satisfied, so that the second shape and the third shape can be fixed. Meet the conditions.

  When the evaluation result of the shape memory property of Table 2 was seen, all of the materials shown in Examples 1 to 3 showed an excellent shape memory property in two stages. Comparative Examples 1 and 4 showed two-stage shape memory. However, Comparative Example 1 can be biodegradable, but cannot be reshaped because the first shape cannot be melted because of irreversible crosslinking (material recycling with excellent energy efficiency is impossible). Moreover, since the comparative example 4 uses the petroleum-type raw material and does not have biodegradation, it is a material inferior to environmental compatibility, and since the 1st shape cannot be melt | dissolved, it cannot recycle. Since Comparative Examples 2 and 3 do not have a crosslinked structure, it is impossible to maintain the three shapes. In Comparative Example 5, the molecular weight of the precursor was about 500, and the first shape restoration was possible. However, since the molecular weight was smaller than in the examples, the degree of crosslinking was high and deformation was difficult. Moreover, since the polybutylene succinate (plant-derived resin material) used here did not crystallize with an increase in the degree of crosslinking (Tm could not be measured), the second shape could not be fixed.

  The product of the present invention having such excellent shape memory property can be used for various molded products such as electronic device members. For example, exterior materials for electronic devices (such as personal computers and mobile phones), screws, fastening pins, switches, sensors, information recording devices, rollers for OA equipment, parts such as belts, packing materials for sockets, pallets, etc. It can be used for on-off valves, heat-shrinkable tubes, etc. In addition, it can be applied in various fields as automobile members such as bumpers, handles, rearview mirrors, household members such as casts, toys, glasses frames, orthodontic wires, bed slip prevention bedding, and the like.

It is a conceptual diagram explaining the principle of the shape memory in the conventional shape memory resin. It is a conceptual diagram explaining the principle of shape memory and remolding in a shape memory resin into which a conventional thermoreversible crosslinking structure is introduced. It is a conceptual diagram explaining the principle of shape memory and remolding in the shape memory resin of this invention. It is a conceptual diagram explaining the application example of two-stage shape memory resin. It is a conceptual diagram which shows an example of the relative relationship of transition temperature.

Claims (13)

Glass transition temperature (Tg) is in the range of −70 ° C. or higher and 10 ° C. or lower, crystal melting temperature (Tm) and crystallization temperature (Tc) are in the range of 40 ° C. or higher and 200 ° C. or lower. A shape memory resin having a thermoreversible cross-linked structure, wherein the thermoreversible cross-linked structure has a cleavage temperature (Td) in the range of 50 ° C. or higher and 300 ° C. or lower and Tm + 10 ° C. ≦ Td. when the deformation temperature at the time of shape recovery is less than or Tm Td, when the shape memory of the second shape, deformation temperature at the time of shape recovery is less than or more Tg Tm, shape in at least two stages storable shape memory resin The thermoreversible cross-linking structure includes Diels-Alder type, nitroso dimer type, acid anhydride ester type, urethane type, azlactone-hydroxyaryl type and carboxyl-alkenyloxy. Shape memory resin which is a least one type selected from the group consisting of the mold.   The shape memory resin according to claim 1, wherein the resin is remoldable at a temperature equal to or higher than Td and lower than a decomposition temperature of the resin. The resin, a shape memory resin of claim 1 or 2 characterized by having a biodegradability. The shape memory resin according to claim 3 , wherein the resin is a resin derived from a plant-derived resin. The shape memory resin according to claim 4 , wherein the resin is a resin using polybutylene succinate or polyhydroxyalkanoate as a raw material. 6. The shape memory resin according to claim 5 , wherein the resin is a Diels-Alder type cross-linked product of polybutylene succinate or polyhydroxyalkanoate in a cooled state. The shape memory resin according to any one of claims 1 to 6 , wherein the resin has a Tm of 40 ° C or higher and 120 ° C or lower. The shape memory resin according to any one of claims 1 to 7 , wherein the resin has a number average molecular weight of one or more precursors of 500 or more and 100,000 or less. A molded article comprising a cross-linked product of the shape memory resin according to any one of claims 1 to 8 . The cross-linked product of the shape memory resin according to any one of claims 1 to 8 is molded into a predetermined first shape to be memorized at a temperature equal to or higher than Td and lower than a decomposition temperature of the resin, and then obtained. A molded body characterized in that the molded body is deformed at a temperature not lower than Tm and lower than Td, and is cooled to a temperature not higher than Tc to fix the deformed shape to give a second shape. The molded body according to claim 10 , wherein the molded body is deformed at a temperature of Tg or more and less than Tm, and cooled to a temperature of less than Tg to fix the deformed shape to give a third shape. . The third shape molded body according to claim 11 is recovered to the memorized original second shape in a temperature range of Tg or more and less than Tm, and is heated to a temperature of Tm or more and less than Td. A method of using a shape memory resin molded product, wherein the molded product is restored to a first shape. A method for regenerating a shape memory resin molded article, comprising melting and remolding the molded article according to claim 10 or 11 at a temperature not lower than Td and lower than a decomposition temperature of the resin.

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