JP2549750B2 - Polyester resin with shape memory - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polyester resin having a shape memory ability.

(Prior Art) Conventionally, as materials having shape memory ability, Ni-Ti system, Cu
Shape memory alloys such as -Ni-Al type, Cu-Zn-Al type, and Cu-Zn-Si type are well known.

Further, as a resin material having a shape memory ability, a polytransisoprene resin (JP-A-55-93806, 61-3
4150), polynorbornene-based resin (JP-A-59-53528)
No. 61-91244), consisting of a mixture of vinyl resin and acrylic acid resin or synthetic rubber (JP-A-63-17).
No. 952) is known.

Due to its excellent physical properties and processability, polyester has been used in a very wide range as fibers, films, bottles, and other general-purpose molded products, but it is theoretically possible to manufacture polyester resins with shape memory capability. Has been suggested (“Nikkei New Material”, 1988 1
To date, no polyester resin that itself exhibits shape memory ability has been known.

(Problems to be Solved by the Invention) The present invention is intended to provide a resin material having excellent shape properties and processability, and having a shape memory ability, which is made of polyester which is an inexpensive general-purpose resin.

(Means for Solving the Problems) As a result of earnest research for producing a polyester resin having shape memory ability, the present inventors have found that a rubber elasticity having a specific glass transition point and for shape deformation is obtained. The present inventors have found that this object can be achieved by introducing an unsaturated bond capable of intermolecular cross-linking for shape memory into a polyester having a polymer and have arrived at the present invention.

That is, the present invention comprises an unsaturated bond comprising an aromatic polyester segment and an aliphatic polyester segment, having a glass transition point in the range of 0 to 100 ° C., and capable of intermolecular crosslinking for shape memory, The gist of the present invention is a polyester resin having shape memory ability, which has rubber elasticity for shape deformation and has an intrinsic viscosity of 0.3 or more.

The polyester resin of the present invention is molded into an arbitrary shape A, and the shape A is fixed and memorized by intermolecular cross-linking. Then, the shape A different from the shape A is once deformed by an external force to obtain a temperature higher than the glass transition point. After fixing the shape B at a low temperature and then heating it to a temperature higher than the glass transition point, it has a function of recovering the shape A, that is, "shape memory ability".

The polyester resin of the present invention has a glass transition point of 0 to 10
0 ℃, preferably 10 to 90 ℃, optimally 20 to 8
It is in the range of 0 ° C.

For polyester resins with a glass transition point of less than 0 ° C, when a shape-memorized molded body is deformed and fixed, the temperature difference from room temperature is large even if it is left at room temperature, and the deformation recovers rapidly. Less is. On the other hand, a polyester resin having a glass transition temperature of more than 100 ° C is too inconvenient to use because the temperature for recovering the shape of the molded product is too high and the shape cannot be recovered with hot water.

The polyester resin of the present invention needs to have an unsaturated bond capable of intermolecular crosslinking. This is because, like the principle of rubber memorizing the shape by vulcanization, the molecules of polyester are cross-linked at certain points to semi-permanently fix the shape to be memorized.

To introduce an unsaturated bond into the polyester resin, a monomer component having an unsaturated bond may be copolymerized. Intermolecular cross-linking becomes possible by cleaving the unsaturated bond by an appropriate means when the shape is fixedly stored.

Examples of the monomer component capable of being copolymerized with polyester and having an unsaturated bond include maleic anhydride, maleic acid, chloromaleic acid, dichloromaleic acid, itaconic acid, fumaric acid, citraconic acid, citraconic anhydride, mesaconic acid, tetrahydro. Examples of the unsaturated dicarboxylic acid or unsaturated diol include phthalic acid, het acid, het anhydride, 2-butene-1,4-diol, 3-butene-1,2-diol.

Further, the polyester resin of the present invention is required to have rubber elasticity for shape deformation in which it deforms when an external force is applied and the original shape is restored when the external force is removed. Rubber elasticity for shape deformation is a reversible behavior of becoming an elastomer in the temperature range above the glass transition point and below the flow start temperature, freely deforming, and hardening at temperatures below the glass transition point. It means the property of causing.

In other words, the polyester resin of the present invention has, in a part of its structure, rubber elasticity which can be a movable part for shape transformation such as deformation and recovery of the molded body after the shape is memorized. It is necessary.

The polyester resin of the present invention is based on an elastomer in which an aromatic polyester segment (hard segment) and a resin group polyester segment (soft segment) are present in a proper ratio.

The aromatic polyester segment means a polyester segment having at least one aromatic ring in the polyester repeating unit, and the aliphatic polyester segment means a polyester segment having no aromatic ring in the polyester repeating unit.

Examples of the aromatic monomer component forming the hard segment include terephthalic acid, isophthalic acid, hydroquinone, dicarboxylic acids such as bisphenol A and 4-hydroxybenzoic acid, diols and hydroxycarboxylic acids.

Examples of the aliphatic monomer component forming the hard segment with the aromatic monomer or forming the soft segment include adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, hexadecanedioic acid, eicosanedioic acid, cyclohexanedicarboxylic acid. , Ethylene glycol, butanediol, hexanediol, nonanediol, cyclohexanedimethanol, γ-butyrolactone, ε-caprolactone and other dicarboxylic acids, diols,
And oxycarboxylic acids (or lactones).

Furthermore, the polyester resin of the present invention has an intrinsic viscosity of 0.
It is necessary to be 3 or more, preferably 0.4 to 2, and most preferably 0.5 to 1. If the intrinsic viscosity is less than 0.3, the minimum required mechanical strength, such as tensile strength, bending strength, and impact strength, will not be satisfied when formed into a molded product.

If necessary, the polyester resin of the present invention may be copolymerized with other auxiliary raw materials as long as the effects of the present invention are not impaired, and may contain various additives.

The monomer component constituting the polyester resin of the present invention and the copolymerization ratio thereof can be selected in a wide range, but in consideration of economical efficiency, versatility, physical properties, etc., for example, the following are preferable.

That is, terephthalic acid as dicarboxylic acid is 20 to 80
Mol%, preferably 40-80 mol%, maleic anhydride at 0.
A polyester resin containing 1 to 30 mol%, preferably 0.5 to 10 mol%, dodecanedioic acid 5 to 40 mol%, preferably 10 to 30 mol%, and ethylene glycol as a diol at 100 mol%.

In this example, the repeating unit consisting of ethylene glycol and terephthalic acid is a hard segment, the repeating unit consisting of ethylene glycol and dodecanedioic acid is a soft segment, and the repeating unit consisting of ethylene glycol and maleic anhydride is the function of introducing an unsaturated bond. To share each.

Next, an example of the method for producing the polyester resin having shape memory ability of the present invention will be specifically described by taking this polyester resin as an example.

The above polyester raw material is charged into an esterification reaction can, and after substitution with nitrogen gas, the temperature is raised to 190 to 270 ° C. under a nitrogen gas pressure of 0.5 to 5.0 kg / cm ² to carry out the esterification reaction.

At this point, it is desirable that the unsaturated bond of maleic anhydride should not be cleaved as much as possible. Therefore, the esterification reaction should be performed in advance only with the other components except maleic anhydride, and then the unsaturated bond of maleic anhydride should be cleaved. The temperature that is difficult and allows the esterification reaction, that is, 160
After lowering the temperature to ~ 240 ° C, it is preferable to add ethylene glycol and maleic anhydride again to complete the esterification reaction.

At this time, it is more preferable to add a free radical polymerization inhibitor such as hydroquinone as an inhibitor of unsaturated bond cleavage.

The obtained esterified product was transferred to a polymerization reaction vessel, and similarly to the above, the unsaturated bond was hard to be cleaved, and polycondensation reaction was possible at a temperature of 180 to 240 ° C for 0.5 to 5 hours at 1 torr or less. The polycondensation reaction is performed under reduced pressure.

After polycondensation until the desired intrinsic viscosity is reached, return to normal pressure with nitrogen gas, pressurize to discharge the polyester in a Tegose shape, and after cooling, cut to obtain a chip-shaped polyester resin having shape memory ability. You can

The polycondensation reaction is usually carried out in the presence of a catalyst. As the polycondensation reaction catalyst, compounds of metals such as antimony, germanium, tin, titanium, and cobalt, which are generally used in the production of polyester, sulfosalicylic acid, o- Organic sulfonic acid compounds such as sulfobenzoic anhydride are used.

Incidentally, the polycondensation reaction catalyst may be added in advance in the esterification step.

Next, an example of a method of semi-permanently fixing and storing the shape A using the polyester resin of the present invention will be described.

Injection molding, extrusion molding or press molding of the above polyester resin at a temperature higher than the flow starting temperature,
A molded body having a shape A is used.

Next, the shape A can be fixedly stored by cross-linking the molded body at a temperature higher than the glass transition point and lower than the flow initiation temperature.

As specific means for cross-linking, irradiation with electron beam or ultraviolet ray, or heat treatment after molding, preferably as a cross-linking agent at the time of molding, ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, peroxy ester. , An organic peroxide such as peroxydicarbonate or an azo compound such as azobisisobutyronitrile may be added and then heat-treated after molding, but the latter method is preferable.

It is preferable that the temperature at which the molded body, which stores the shape A made of the polyester resin of the present invention, is deformed to obtain the molded body having the shape B is not less than the glass transition point. The method of giving the deformation is not particularly limited, and the deformation can be given under a temperature atmosphere (for example, in heated air, heated liquid, steam, etc.) that easily deforms the molded body according to the shape and thickness of the molded body.

In order to fix the deformation, it is sufficient to cool the molded body, which has been deformed under the above conditions, to below the glass transition point while maintaining the deformation.

In order to return the molded body of shape B to the molded body of shape A, it is sufficient to heat the glass body to a temperature not lower than the glass transition point and lower than the flow starting temperature, and the deformation automatically occurs to restore the shape A. Generally, the higher the temperature, the shorter the time required for the molded body to recover the shape A.

When all the copolymerized unsaturated bonds are consumed for crosslinking, as described above, the shape A that is semi-permanently fixed and stored cannot be erased, but the copolymerized unsaturated bond has a shape A. Elimination is possible by taking a specific structure, such as when not being consumed for cross-linking at the time of fixation and storage, still remaining as unsaturated bonds in polyester, and when the number of cross-linking points is small. In some cases,
Furthermore, it may be possible to re-store.

The shape-retaining polyester resin of the present invention is used for joining materials such as pipes and electric wires, sealing materials, internal and external laminating materials for pipes and rod-shaped parts, covering materials for objects, work such as tightening pins and clamps, and construction. Fixing materials, medical equipment materials such as balloon catheters, portable containers and tableware that are folded when not in use to recover their shape when used, members that require deformation recovery after shock absorption such as automobile bumpers, for toys It can be used for members, stationery materials, decorative members such as artificial flowers and broaches, electric members such as heat-sensitive switches, packings, O-rings, molding materials, and various other leisure tools.

(Operation) When the polyester resin of the present invention undergoes intermolecular cross-linking, a stationary phase (cross-linking point) is formed to prevent the flow of the resin and give a certain shape, and is softened with temperature change. It is presumed that shape memory becomes possible in combination with the plastic phase (soft segment and hard segment) that causes hardening reversibly and exerts a memory recovery function.

(Example) Next, an Example is given and this invention is described.

The characteristic values of the polyester resin in the examples are measured as follows.

Intrinsic Viscosity [η] An equal weight mixture of phenol and ethane tetrachloride was used as the solvent, and the temperature was measured at 20 ° C.

Glass transition point (Tg) Differential running calorimeter (DSC-2 type manufactured by Perkin Elmer)
Was measured at a heating rate of 20 ° C / min.

Flow start temperature (Tf) Using a flow tester (Shimadzu CFT-500 type),
Initial temperature 50 ℃ under the condition of load 100kg / cm ² and nozzle diameter 0.5mm
The temperature was then raised at a rate of 10 ° C / min, and the temperature was determined as the temperature at which the polymer began to flow out of the die.

Existence of shape memory ability After molding a polyester resin into a shape that you want to remember at a temperature about 20 ° C higher than Tf,
A heat treatment was performed for 0 minutes to fix and store the shape, and the obtained molded body was judged to have the shape memory ability or not according to the following criteria.

Shape memory ability: It is possible to fix the deformation below Tg, to recover the complete shape above Tg, and to not deform when left at a temperature below Tg.

No shape memory ability: Unfixed or incomplete deformation below Tg or unfixed or incomplete recovery of fixed deformation above Tg.

Example 1 To 35.0 kg of bis (β-hydroxyethyl terephthalate) and its oligomer obtained by the esterification reaction of terephthalic acid and ethylene glycol, dodecanedioic acid 5.
8 kg, ethylene glycol 9.5 kg, and tetrabutyl titanate 26 g as a catalyst were added, and the temperature was 250 ° C and nitrogen gas pressure was 3.6 kg.
After esterification reaction at 2 / cm ² for 2 hours, the temperature was lowered to 220 ° C, 4.9 kg of maleic anhydride was added, and further 220 ° C, under nitrogen gas pressure suppression.
The esterification reaction was carried out at 3.6 kg / cm ² for 2 hours.

The obtained esterified product was transferred to a polycondensation reactor,
Polycondensation reaction was carried out at the temperature of 0.4 torr for the time shown in Table 1.

The obtained polyester resin was extruded at a temperature of 210 ° C. to obtain a Tex-like material having a diameter of 3 mm.

Then, wrap the wire around the iron bar with a diameter of 2 cm,
A cross-linking reaction was carried out in a hot air dryer at 0 ° C for 30 minutes to form a spring-shaped molded body.

In order to evaluate the shape memory ability, the obtained spring-shaped compact was linearly deformed in hot water at 60 ℃, the deformation was temporarily fixed in water at 20 ℃, and then hot water at 60 ℃ was used again. When it was dipped in the inside and the degree of shape recovery was evaluated, it was a polyester resin having a good shape memory ability.

In addition, a Tex-like material obtained in the same manner as in Example 1 had a diameter of 2c.
The deformation was temporarily fixed in water at 20 ° C without being cross-linked by winding it around a m steel rod, but it was impossible.

Example 2 A polyester resin was produced in the same manner as in Example 1 except that dodecanedioic acid was 11.5 kg and maleic anhydride was 2.5 kg. Molding was performed to determine the presence / absence of shape memory ability. It showed shape memory ability.

Example 3 A polyester resin was produced and molded in the same manner as in Example 1 except that 3.7 kg of adipic acid was used instead of dodecanedioic acid, and the molded resin was evaluated for its shape memory ability. Showed Noh.

Example 4 A polyester resin was produced in the same manner as in Example 1 except that 6.5 kg of itaconic acid was used in place of maleic anhydride, and was molded to determine the presence / absence of shape memory ability.
It showed a good shape memory ability.

Comparative Example 1 Bis (β-hydroxyethyl terephthalate) obtained by the esterification reaction of terephthalic acid and ethylene glycol and 40.0 kg of its oligomer were mixed with maleic anhydride.
4.9 kg, 6.2 kg of ethylene glycol and 26 g of tetrabutyl titanate as a catalyst were added, and the temperature was adjusted to 3.6 at 220 ° C under nitrogen gas suppression.
The esterification reaction was carried out at kg / cm ² for 2 hours.

The obtained esterified product was transferred to a polycondensation reactor, and 220 ° C
Polycondensation reaction was performed at 0.4 torr for the time shown in Table 1 to obtain a polyester resin.

The polyester resin thus obtained was extruded at a temperature of 210 ° C. to obtain a gut-like material having a diameter of 3 mm.

Then, wrap the wire around the iron bar with a diameter of 2 cm,
A cross-linking reaction was carried out for 30 minutes in a hot air dryer at 0 ° C to obtain a spring-shaped molded body.

In order to evaluate the shape memory ability, we tried to deform the obtained spring-shaped compact linearly in hot water at 60 ° C, but the rubber elasticity was poor, and the shape could not be deformed, resulting in damage. Oops.

Table 1 shows the characteristic values of the polyesters obtained in Examples 1 to 4 and Comparative Example 1 and the presence / absence of shape memory.

(Effects of the Invention) According to the present invention, there is provided a resin material having excellent physical properties and processability, and having a shape memory ability, which is made of polyester which is an inexpensive general-purpose resin.

The polyester resin of the present invention can be used in various applications as described above and has a high industrial utility value.

Claims (2)

(57) [Claims] 1. A composition comprising an aromatic polyester segment and an aliphatic polyester segment and having a glass transition point of 0 to
A shape in the range of 100 ° C., having an unsaturated bond capable of intermolecular crosslinking for shape memory, rubber elasticity for shape deformation, and an intrinsic viscosity of 0.3 or more A polyester resin with memory. 2. A polyester resin comprising 20-80 mol% terephthalic acid, 0.1-30 mol% maleic anhydride and 5-40 mol% dodecanedioic acid and ethylene glycol 100.
The polyester resin having shape memory ability according to claim 1, which is composed of a diol component consisting of mol%.