JPH0457813A - Polyester resin having shape memory capacity - Google Patents

Abstract

PURPOSE:To form a polyester resin having a shape memory capacity by introducing a chemical structure capable of intermolecular crosslinking for shape memory into a polyester having a specified glass transition point and rubberlike elasticity for shape deformation. CONSTITUTION:This polyester resin having a shape memory capacity has a glass transition point of 0-100 deg.C, a chemical structure capable of intermolecular crosslinking for shape memory and rubberlike elasticity for shape deformation, and an intrinsic viscosity of 0.3 or above. As the polyester resin, one comprising an aromatic polyester segment and an aliphatic polyester segment and having an unsaturated bond for shape memory is desirable. For example, a polyester resin prepared from a discarboxylic acid component comprising 20-80 mol% terephthalic acid, 0.1-30 mol% maleic anhydride and 5-40 mol% dodecandioic acid and a diol component comprising 100 mol% ethylene glycol is desirable.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a polyester resin having shape memory ability.

(Prior art) Conventionally, materials with shape memory include Ni-Ti.
system, Cu-Ni-Al system, Cu-Zn-Al system,
Shape memory alloys such as Cu-Zn-3i series are well known.

Also, as a resin material with shape memory ability.

Polytrans isoprene resin (JP-A-55-9380
6, No. 61-34150), polynorbornene resins (JP-A-59-53528, JP-A No. 61-91244), mixtures of vinyl resins and acrylic acid resins or synthetic rubber (JP-A No. 59-53528, JP-A No. 61-91244); No. 17952 (Sho 63-17952), etc. are known.

Now, due to its excellent physical properties and processability, polyester has been used extremely widely as fibers, films, bottles, and other general-purpose molded products, but polyester resin with shape memory ability can theoretically be manufactured. (Nikkei New Materials J, 198
(November 28, 2008 issue, p. 49) However, to date, no polyester resin is known that exhibits shape memory ability itself.

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

(Means for Solving the Problems) As a result of intensive research to produce a polyester resin having shape memory ability, the present inventors found that it has a specific glass transition point and has rubber elasticity for shape deformation. The present invention was achieved by discovering that this object can be achieved by introducing a chemical structure capable of intermolecular crosslinking for shape memory into a polyester having a shape memory.

In other words, the present invention has a glass transition point in the range of 0 to 100°C, a chemical structure capable of intermolecular crosslinking of a shape memory ladle, and rubber elasticity for shape deformation, and has an extremely The gist of the invention is a polyester resin having shape memory ability, characterized by a viscosity of 0.3 or more.

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

The polyester resin of the present invention has a glass transition point of 0 to 10.
0°C, preferably in the range of 10-90°C, optimally 20-80°C.

If a polyester resin with a glass transition point of less than 0°C is deformed and fixed with shape memory, even if it is left at room temperature, the deformation will quickly recover due to the large temperature difference from room temperature, making it unsuitable for practical use. There are few benefits. On the other hand, polyester resins whose glass transition point exceeds 100° C. are inconvenient in use because the temperature at which the shape of the molded product is recovered is too high, and the shape cannot be recovered with hot water.

It is necessary that the polyester resin of the present invention has a chemical structure capable of crosslinking between two molecules. This is similar to the principle by which rubber memorizes its shape through vulcanization.

This is to crosslink the polyester molecules at key points and semi-permanently fix the shape to be memorized.

A specific example of a chemical structure capable of intermolecular crosslinking is copolymerizing monomer components having unsaturated bonds to introduce unsaturated bonds into the main chain of polyester. By cleaving this unsaturated bond by an appropriate means when fixing the shape, crosslinking between nine molecules becomes possible.

Monomer components that can be copolymerized into polyester and have unsaturated bonds include, for example, maleic anhydride, maleic acid, chloromaleic acid, dichloromaleic acid, itaconic acid, fumaric acid, and citraconic acid.

Examples include unsaturated dicarboxylic acids or unsaturated diols such as citraconic anhydride, mesacone L, tetrahydrophthalic acid, het acid, het acid anhydride, 2-butene-1,4-diol, and 3-butene-1,2-diol. .

Another effective method is to copolymerize polyester with a trifunctional or higher functional component. In this case, in order to memorize the shape, it is possible to perform intermolecular crosslinking by adding a crosslinking agent having an epoxy group, isocyanate group, amino group, etc. that can crosslink with the hydroxyl group or carboxyl group of the polyester. It becomes possible.

The method of introducing a structure capable of intermolecular crosslinking into polyester is not particularly limited, but the method of introducing unsaturated bonds described above is practically preferred.

Further, the polyester resin of the present invention needs to have rubber elasticity for shape deformation, such that it deforms when external force is applied to it and recovers its original shape when the external force is removed. Rubber elasticity for shape deformation is a reversible behavior in which it becomes elastomer-like in the temperature range above the glass transition point and below the flow start temperature, deforms freely, and becomes hard at temperatures below the glass transition point. Refers to the property of causing something.

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

Specific examples of methods for imparting rubber elasticity to polyester resins include methods for forming an elastomer in which aromatic polyester segments (hard segments) and aliphatic polyester segments (soft segments) exist in an appropriate ratio; Examples include a method of preparing an elastomer containing a moderate proportion of a polyalkylene glycol segment (hard segment) and a polyalkylene glycol segment (soft segment), but the former is preferred.

An aromatic polyester segment refers to a polyester segment that has at least one aromatic ring in a polyester repeating unit, and an aliphatic polyester segment refers to a polyester segment that does not have an aromatic ring in a polyester repeating unit.

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

Examples of aliphatic monomer components that constitute hard segments with aromatic monomers or soft segments include adipic acid, azelaic acid, sebacic acid, dodecaniic acid, hexadecanniic acid, and eicosanniic acid9. Cyclohexanedicarboxylic acid, ethylene glycol, butanediol, hexanediol, nonanediol, cyclohexane dimetatool, T-butyrolactone.

Dicarboxylic acids and diols such as ε-caprolactone.

and oxycarboxylic acids (or lactones).

Further, polyalkylene glycols such as polyethylene glycol and polytetramethylene glycol can also function as soft segment components.

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

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

The monomer components constituting the polyester resin of the present invention and their copolymerization ratio can be selected from a wide range.

For example, considering economic efficiency, versatility, physical properties, etc.

The following are preferred.

That is, 20 to 8 terephthalic acid as dicarboxylic acid
0 mol%, preferably 40-80 mol%, maleic anhydride 0.1-30 mol%, preferably 0.5-10 mol%, dodecanniic acid 5-40 mol%, preferably 10-
30 mol%, 10 ethylene glycol as diol
The polyester resin was used in a proportion of 0 mol%.

In this example, the repeating unit composed of ethylene glycol and terephthalic acid serves as a hard segment, the repeating unit composed of ethylene glycol and dodecanedioic acid serves as a soft segment, and the repeating unit composed of ethylene glycol and maleic anhydride serves the function of introducing an unsaturated bond. Each will share their share.

Next, an example of the method for producing a polyester resin having shape memory ability according to the present invention will be specifically explained using this polyester resin as an example.

Putting the polyester raw material into an esterification reaction can,
After nitrogen gas substitution, the temperature is raised to 190 to 270° C. under nitrogen gas pressure of 0.5 to 5.0 kg/cnf to perform an esterification reaction.

At this point, it is desirable to prevent the unsaturated bonds of maleic anhydride from being cleaved as much as possible. Therefore, an esterification reaction is performed in advance using only the other components except maleic anhydride, and then the unsaturated bonds of maleic anhydride are cleaved. To＜＜
, and the temperature at which the esterification reaction is possible, i.e. 16
After the temperature is lowered to 0 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 reactor.

As above, the unsaturated bond is cleaved <<, and.

At a temperature of 180 to 240°C where polycondensation reaction is possible, 0.5
The polycondensation reaction is carried out under reduced pressure of less than 1 Torr for ~5 hours.

After polycondensing until the desired intrinsic viscosity is achieved, the pressure is returned to normal pressure with nitrogen gas, the polyester is pressurized and the polyester is paid out in the form of sticks, and after cooling, the polyester resin is cut to obtain a chip-like polyester resin having shape memory ability. I can do it.

Polycondensation reactions are usually carried out in the presence of a catalyst.

Antimony and germanium, which are commonly used in the production of polyester, are used as polycondensation reaction catalysts.

Compounds of metals such as tin, titanium, and cobalt and organic sulfonic acid compounds such as sulfosalicylic acid and 0-sulfobenzoic anhydride are used.

In addition, a polycondensation reaction catalyst can also be added in advance in the esterification step.

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

A molded article having a shape A is formed by injection molding, extrusion molding, or press molding the above polyester resin at a temperature higher than the flow start temperature.

Next, this molded body is heated to a temperature higher than the glass transition point.

By crosslinking at a temperature lower than the flow start temperature, shape A can be fixedly memorized.

Specific means for crosslinking include irradiation with electron beams or ultraviolet rays, or heat treatment after molding, preferably using ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, peroxy as a crosslinking agent during molding. It is possible to add an organic peroxide such as ester or peroxydicarbonate, or an azo compound such as azobisisobutyronitrile, and then perform heat treatment after molding, but the latter method is preferred.

The temperature at which deformation is applied to transform a molded article having a memorized shape A made of the polyester resin of the present invention into a molded article having a shape B is preferably at least the glass transition point. There are no particular restrictions on how the deformation is applied, and the deformation can be applied in a temperature atmosphere that facilitates deformation of the molded product (for example, in heated air, heated liquid, water vapor, etc.) depending on the shape and wall thickness of the molded product.

In order to fix the deformation, the molded body deformed under the above conditions may be cooled to below the glass transition point while maintaining the deformation.

To return a molded body of shape B to a molded body of shape A.

It is only necessary to heat the material to a temperature higher than the glass transition point and lower than the flow start temperature, and the deformation occurs automatically and the shape A is restored. Generally, the higher the temperature, the shorter the time for the molded body to recover to shape A.

Note that if all the copolymerized unsaturated bonds are consumed by crosslinking, the semi-permanently fixed and memorized shape A cannot be erased, but the copolymerized unsaturated bonds During fixation and storage, all of the polyester is not consumed by crosslinking and still remains as unsaturated bonds in the polyester.

In some cases, such as when the number of cross-linking points is small, it may be possible to erase or even re-memorize by having a specific structure.

The polyester resin with shape memory ability of the present invention can be used as a joining material or sealing material for pipes and electric wires, as a laminate material for the inside or outside of pipes and rod-shaped articles, as a covering material for objects, and as a material for tightening with pins, clamps, etc. Architectural fixing materials, medical equipment materials such as balloon catheters.

Components that require deformation recovery after impact absorption, such as portable containers, tableware, and automobile bumpers that are folded when not in use and then restored to their original shape when in use.

Toy component 1 It can be used for stationery materials, decorative components such as artificial flowers and brooches, electrical components such as heat-sensitive switches, packing materials, O-rings, molding materials, and various other leisure tools.

(Function) When the polyester resin of the present invention undergoes 9-molecular crosslinking, a stationary phase (crosslinking point) is formed that prevents the resin from flowing and develops a certain shape, and it softens with temperature changes. A plastic phase that hardens reversibly and exerts a memory recovery function (
It is presumed that shape memory becomes possible in combination with soft segments and hard segments).

(Example) Next, the present invention will be described with reference to examples.

In addition, in the examples, the characteristic values of the polyester resin were measured as follows.

Intrinsic viscosity [η] Measured at a temperature of 20° C. using an equal weight mixture of phenol and tetrachloroethane as a solvent.

Glass transition point (Tg) Differential scanning calorimeter (PerkinElmer DSC-2 model)
The measurement was performed using a temperature increasing rate of 20° C./min.

Flow start temperature (Tf) Using a flow tester (CFT-500 model manufactured by Shimadzu Corporation), under the conditions of a load of 100 kg/cut and a nozzle diameter of 0.5 mm.

The temperature was increased from the initial temperature of 50° C. at a rate of 10° C./min, and the temperature was determined as the temperature at which the polymer began to flow out from the goo.

Presence or absence of shape memory ability After molding the polyester resin into the desired shape to be memorized at a temperature approximately 20°C higher than Tf, heat treatment is performed at a temperature approximately 20°C lower than Tf for 30 minutes to fix and memorize the shape,
The molded product obtained was evaluated for shape memory ability based on the following criteria.

Has shape memory ability: Deformation can be fixed at temperatures below Tg, and complete shape recovery is possible at temperatures above 18.

Items that do not deform when left at temperatures with no Tg drops.

No shape memory ability: Those whose deformation cannot be fixed or are incomplete at Tg or below, or those whose fixed deformation cannot be recovered or are incomplete at temperatures above 18.

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, 5.8 kg of dodecanoic acid, 9.5 kg of ethylene glycol, and tetrabutyl titanate as a catalyst were added. Add 26g, 250
After esterification reaction at 3.6 kg/cJ at 220°C under nitrogen gas pressure for 2 hours, the temperature was lowered to 220°C, 4.9 kg of maleic anhydride was added, and further esterification was carried out at 220°C and nitrogen gas under pressure for 3.
The esterification reaction was carried out at 6 kg/cnf for 2 hours.

Transfer the obtained esterified product to a polycondensation reactor.

A polyester resin was obtained by carrying out a polycondensation reaction at 220°C and 0.4°C for the times shown in Table 1.

The obtained polyester resin was extrusion molded at a temperature of 210° C. to form a rod-like product with a diameter of 3n+m.

Next, wrap this string-like object around a 2cm diameter iron rod,
A crosslinking reaction was carried out in a hot air dryer at 150° C. for 30 minutes to obtain a spring-shaped molded product.

In order to evaluate the shape memory ability, the obtained spring-like molded body was deformed linearly in hot water at 60°C, and then heated at 20°C.
The deformation was temporarily fixed in water at 60° C., and the resin was immersed again in hot water at 60° C. to evaluate the degree of shape recovery. As a result, the polyester resin had good shape memory ability.

Note that the length of the rod-like material obtained in the same manner as in Example 1 was 2 cm in diameter.
Wrap it around an o+ iron rod, without causing a crosslinking reaction, for 20
An attempt was made to temporarily fix the deformation in water at ℃, but fixation was impossible.

Example 2 115 kg of dodecanniic acid, 2.5 kg of maleic anhydride
A polyester resin was produced in the same manner as in Example 1 except that the polyester resin was molded and the presence or absence of shape memory ability was determined, and it was found to have good shape memory ability.

Example 3 A polyester resin was produced in the same manner as in Example 1 except that 3.7 kg of adipic acid was used instead of dodecanedioic acid, and the resin was molded to determine the presence or absence of shape memory ability.
It showed good shape memory ability.

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 instead of maleic anhydride, and when it was molded to determine whether it had shape memory ability, it was found that it had a good shape. Demonstrated memory ability.

Comparative Example 1 40.0 kg of bis(β-hydroxyethyl terephthalate) obtained by esterification reaction of terephthalic acid and ethylene glycol and its oligomer, 1 ton of maleic anhydride, 24.9 kg, and 6.2 kg of ethylene glycol.
and adding 26 g of tetrabutyl titanate as a catalyst,
The esterification reaction was carried out at 220° C. for 2 hours at 3.6 kg/c++f under nitrogen gas pressure.

The obtained esterified product was transferred to a polycondensation reactor.

A polyester resin was obtained by carrying out a polycondensation reaction at 220° C. and 0.4 μl for the time shown in Table 1.

The obtained polyester resin was extrusion molded at a temperature of 210° C. to form a rod-like product with a diameter of 3 mm.

Next, wrap this string-like object around a 2cm diameter iron rod,
A crosslinking reaction was performed in a hot air dryer at 150° C. for 30 minutes to form a spring-shaped molded product.

In order to evaluate the shape memory ability, an attempt was made to deform the obtained spring-like molded body into a linear shape in hot water at 60°C, but the rubber elasticity was poor and the shape could not be deformed, resulting in breakage. Oops.

The characteristic values and the presence or absence of shape memory ability of the polyesters obtained in Examples 1 to 4 and Comparative Example 1 are summarized in Table 1.

(Effect of the invention) According to the present invention, it has excellent physical properties and processability.

A resin material having shape memory ability made of polyester, which is an inexpensive general-purpose resin, is provided.

The polyester resin of the present invention can be used for various purposes as mentioned above, and has high industrial utility value.

Patent applicant: Nihon Ester Co., Ltd.

Claims (2)

[Claims] (1) It has a glass transition point in the range of 0 to 100°C, a chemical structure that allows intermolecular crosslinking for shape memory, and rubber elasticity for shape deformation, and an intrinsic viscosity of 0. A polyester resin having a shape memory ability of 3 or more. (2) The polyester resin having shape memory ability according to claim 1, wherein the polyester resin is composed of an aromatic polyester segment and an aliphatic polyester segment and has an unsaturated bond for shape memory.