JPH05200864A - Shape memory polyester molded article having heat generation properties - Google Patents

Abstract

PURPOSE:To provide a shape memory polyester molded article having heat generation properties suitable for food packing, clothing or a sanitrary material. CONSTITUTION:A shape memory polyester molded article consists of a copolyester A based on a dicarboxylic acid component consisting of two or more kinds of dicarboxylic acid components containing 70mol% or more of aromatic dicarboxylic acid and one or more kinds of an aliphatic diol component and having a glass transition point of 10-80 deg.C and shape memory capacity and polyester B having an m.p. equal to or higher than the glass transition point of copolyester A but below the m.p. thereof and crystallization heat of 10mJ/mg or more at the time of temp. fall and generating the latent heat change accompanied by the phase change of melting and solidification and polyester B is arranged in copolyester A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shape-memory polyester molded product having an exothermic property.

[0002]

2. Description of the Related Art In recent years, a polymer having a shape memory ability has been attracting attention, and polytransisoprene type, polynorbornene type, polyester type and the like have been proposed.
Among these, polyester-based ones are cheaper than other polymers, and have excellent physical properties and moldability.

As the polyester having a shape memory ability, a block copolymer of polybutylene terephthalate and an aliphatic polylactone (JP-A-2-123129) and a block copolymer of polybutylene terephthalate and polyethylene glycol (JP-A-2123). -240135), a copolyester such as a copolymer of poly (ethylene terephthalate / isophthalate) and polyethylene glycol (JP-A-2-
No. 269735) is proposed. However, such a conventionally proposed copolyester having a shape memory capacity has a problem of poor thermal stability and light resistance.

Further, a shape-memory polyester molded product having an exothermic property is required for some applications, but such a molded product has not been heretofore known. As a method of giving exothermicity to the polyester having shape memory ability, a method of compounding a latent heat type heat storage agent or a metal powder that efficiently absorbs sunlight, a dielectric substance, a semiconductor substance, etc. can be considered. In the method (1), there is a problem that the supercooling phenomenon occurs and thus the stability is poor, and the color tone is deteriorated depending on the compounded substances, so that the use is limited.

[0005]

DISCLOSURE OF THE INVENTION The present invention is intended to provide a shape-memory polyester molded article having an exothermic property without the above-mentioned drawbacks.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have used a copolyester having a specific shape-memory ability on the surface of a molded article and have a thermoplastic property having crystallization characteristics. The inventors have found that it is preferable to use a polymer as a composite molded article used inside the molded article, and arrived at the present invention.

That is, the gist of the present invention is as follows. Consists of two or more types of dicarboxylic acid components, 70 mol% or more of which are aromatic dicarboxylic acids, and one or more types of aliphatic diol components as main components, and has a glass transition point of 10 to 80 ° C or higher. Copolyester A, which has shape memory ability, and melting point of copolyester A which is higher than glass transition point and lower than melting point, heat of crystallization is 10 mJ / mg or more when cooling, and latent heat change accompanying phase change of melting and solidification A shape-memory polyester molded article having heat generating properties, characterized in that the polyester B is disposed inside the copolyester A, and the polyester B is disposed inside the copolyester A.

The present invention will be described in detail below. The surface portion of the molded article of the present invention is composed of a copolyester having a shape memory ability. Here, the shape memory ability is formed into an arbitrary shape X, the shape X is fixedly memorized by heat treatment, and then temporarily deformed by an external force to a shape Y different from the shape X at a temperature higher than the glass transition point. After fixing the shape Y by cooling to a temperature lower than the glass transition point, the shape Y is recovered by heating to a temperature higher than the glass transition point.

The copolyester A in the present invention must first have a glass transition point of 10 to 80 ° C., preferably 20 to 70 ° C., and most preferably 40 to 60 ° C. If the glass transition point is less than 10 ° C, it becomes an elastomer at room temperature and cannot be used as a molded product. Also,
When the glass transition point exceeds 80 ° C, it is necessary to raise the temperature for shape recovery, which is not practical.

Further, the copolyester A is required to form a crystalline phase and an amorphous phase appropriately by heat treatment and is composed of two or more kinds of dicarboxylic acid components.
It is necessary that the main component is a dicarboxylic acid component in which 70 mol% or more is an aromatic dicarboxylic acid and one or more aliphatic diol components. The homopolymer has too many crystalline phases, and there are few amorphous phases that serve as moving parts for shape recovery, and sufficient shape memory ability cannot be exhibited. Further, if the proportion of the aromatic dicarboxylic acid component is less than 70 mol%, a molded product having sufficient strength cannot be obtained. Whether or not a crystal phase is formed can be determined by measurement with a differential scanning calorimeter, and if the heat of crystal fusion ΔHm appears, it can be determined that a crystal phase is formed.

Further, copolyester A has an intrinsic viscosity
A value of 0.3 or more, preferably 0.4 to 2.0, and most preferably 0.5 to 1.0 is suitable. If the intrinsic viscosity is less than 0.3, the mechanical strength as a molded product is insufficient, and if it exceeds 2.0,
The melt viscosity is high, the fluidity is low, and the moldability is poor, which is not preferable.

When all the dicarboxylic acid components are composed of aromatic dicarboxylic acids, it may be difficult to form a crystal phase. For example, when terephthalic acid and isophthalic acid are used, the crystallinity tends to significantly decrease as the proportion of isophthalic acid increases, and the crystal phase cannot be formed.
It is necessary to set the ratio of isophthalic acid to about 5 to 15 mol%. When an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid are used in combination, a copolyester having an appropriate degree of crystallinity can be easily obtained.

Examples of the aromatic dicarboxylic acid component include terephthalic acid, isophthalic acid, 1,4-naphthalenedicarboxylic acid, 2,4-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid and diphenoxyethanedicarboxylic acid. Examples of the aliphatic dicarboxylic acid component include dodecanedioic acid, azelaic acid and sebacic acid.

On the other hand, examples of the aliphatic diol component include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,9-nonanediol and neopentyl glycol. ..

If necessary, the copolyester A may be copolymerized with an unsaturated dicarboxylic acid having an intermolecular crosslinkable structure, an unsaturated diol, and a tri- or higher functional compound. Further, in the copolyester A, aromatic diols such as bisphenol A and p, p'-biphenol and other auxiliary materials are copolymerized, if necessary, within a range that does not impair the shape memory ability and the spinnability. It may also contain additives such as stabilizers, fluorescent agents and pigments.

The components constituting the copolyester A and the copolymerization ratio thereof in the present invention can be selected within a wide range, but from the viewpoints of economical efficiency, versatility, physical properties, etc., terephthalic acid is 70 to 95 mol%, preferably 80 to Most preferred is a copolyester composed of ethylene glycol and a dicarboxylic acid component consisting of 93 mol% and 5 to 30 mol% dodecanedioic acid, preferably 7 to 20 mol%.

Next, the polyester B in the present invention is
The melting point must be higher than or equal to the glass transition point of copolyester A and lower than the melting point. This is because the copolyester A must be in a molten state when heated to a temperature at which it recovers its shape, that is, at a temperature at which deformation is released. Polyester B must have good crystallization during cooling, and the heat of crystallization during cooling is 10 mJ.
/ Mg or more, it is necessary to be 30mJ
/ Mg or more, optimally 50 mJ / mg or more. When the heat of crystallization is less than 10 mJ / mg, the exothermic effect is small and the heat retaining effect is not substantially obtained. The polyester B includes a linear aliphatic polyester obtained from a linear aliphatic dicarboxylic acid component and a linear aliphatic diol component, and a linear aliphatic polyester such as polycaprolactone.

Examples of the straight-chain aliphatic dicarboxylic acid component include glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid and eicosanedioic acid.

On the other hand, as the straight-chain aliphatic diol component,
Ethylene glycol, 1,3-propanediol, 1,4-
Examples thereof include butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol and the like.

Two or more kinds of the aliphatic dicarboxylic acid component and the aliphatic diol component may be used in combination, and terephthalic acid, isophthalic acid, 5-sodium sulfoisophthalic acid, succinic acid and trimellitic acid may be used as long as the exothermic effect is not deteriorated. ,
Hydroxybenzoic acid, 1,4-cyclohexanedicarboxylic acid, diethylene glycol, 1,4-cyclohexanedimethanol, etc. may be used together as a copolymerization component, or additives such as matting agents, stabilizers, and colorants may be added. ..

The heat of crystallization of polyester B when the temperature is lowered can also be controlled by incorporating a crystal nucleating agent. Crystal nucleating agents include talc, silica, glass chopped strands, titanium dioxide, calcium silicate,
Inorganic compound fine particles such as antimony trioxide, magnesium stearate, organic acid salt fine particles such as sodium benzoate, ethylene oxide adduct of disodium sulfobisphenol A, fluororesin, organic silicone,
Polyacrylic acid crosslinked products, polystyrene crosslinked products, fine particles of organic compounds such as polyarylate, and the like can be used, and two or more kinds may be used in combination. When the crystal nucleating agent is contained, it is suitable to contain it in an amount of 0.01 to 3.0% by weight. If the content is too small, the effect as a crystallization accelerator will be poor, and conversely, if it is too large, the moldability will be poor.

The molded article of the present invention uses the above-described copolyester A and polyester B, where A is the surface portion and B is
Is formed so as to form the inside thereof, and is heat-treated at a temperature not lower than the glass transition point and not higher than the melting point of the copolyester A. The form of the molded product can be appropriately selected depending on the application, such as fiber, film, various molded products and the like. Specific examples thereof include a form in which polyester B is enclosed inside a hollow body of copolyester A, and a laminated film having copolyester A as a surface layer and polyester B as an inner layer. The ratio of the copolyester A to the polyester B is 1: 2 by weight in consideration of heat generation and shape memory.
2: 1 is suitable.

The temperature at which the molded article of the present invention is deformed is preferably at least the glass transition point of the copolyester A. The method for giving the deformation is not particularly limited, and the deformation can be given in a temperature atmosphere (for example, heated air, heated liquid, steam) which is easily deformed according to the form, wall thickness and the like of the molded product. In order to fix the deformation, it is sufficient to cool it below the glass transition point of copolyester A while maintaining the deformation. In order to remove the deformation from the molded article and restore the memorized shape, it suffices to heat it to a temperature not lower than the glass transition point of the copolyester A and not higher than the melting point and higher than the melting point of the polyester B, and the deformation is automatically released. Shape recovers. Generally, the higher the temperature, the shorter the time required for the molded product to recover to a predetermined shape. Polyester B melted as the temperature of the molded article decreases due to the influence of the outside temperature
Is solidified and crystallized to release heat of crystallization, and the heat of crystallization causes the molded article to exhibit heat generation.

[0024]

EXAMPLES The present invention will now be described by way of examples. The measurement and evaluation methods are as follows. (a) Intrinsic viscosity [η] Measured at a temperature of 20 ° C using an equal weight mixture of phenol and ethane tetrachloride as a solvent. (b) Melting point and crystallization characteristics: Measured under the following conditions using a differential scanning calorimeter DSC-2 type manufactured by Perkin Elmer. In a nitrogen stream, the temperature is raised from -30 ℃ to 280 ℃ at a heating rate of 10 ℃ / min, and held for 5 minutes. After that, the temperature is lowered to -30 ℃ at a cooling rate of 10 ℃ / min, and held for 3 minutes. Raise the temperature to 280 ° C at a heating rate of 10 ° C / min. Again, the melting peak temperature at the time of temperature rise is the melting point Tm, the peak of the crystallization temperature at the time of temperature decrease is the temperature decrease crystallization temperature Tc, and the crystallization peak area at the time temperature decrease is the heat of crystallization ΔHc. (c) Presence or absence of shape memory property Shape memory property: Deformation can be fixed at a temperature below the glass transition point Tg of copolyester A, it does not deform when left at a temperature below Tg, and at a temperature above Tg. A shape whose shape is completely restored by heating. No shape memory property: Fixation of deformation is impossible or incomplete at a temperature lower than Tg of copolyester A, or shape recovery is impossible or incomplete even when heated to a temperature higher than Tg. (d) Exothermic Copolyester A with Tg or more and Tm or less, polyester B
It is heated to a temperature where it melts, left in an atmosphere of 10 ° C, and a surface thermometer is attached to the molded product to measure the temperature. As a blank, a molded product made of polyethylene terephthalate is similarly measured. The temperature difference between the two is obtained to evaluate heat generation.

Example 1 Dodecanedioic acid, ethylene glycol and tetrabutyl titanate as a catalyst were added to bis (β-hydroxyethyl) terephthalate and its oligomer obtained by the esterification reaction of terephthalic acid and ethylene glycol, and 250 ° C. The esterification reaction was carried out for 2 hours. The esterification reaction product was then transferred to a polycondensation reactor and gradually depressurized while raising the temperature, and finally at 280 ° C. and 0.4 Torr, 4
A time-wise polycondensation reaction was performed to obtain a copolyester (A) having a shape memory ability. I got it. The obtained copolyester
(A) has a copolymerization amount of dodecanedioic acid of 10 mol%, and has [η] of 0.
It was 50, Tg 47 ° C and Tm 238 ° C.

Adipic acid and 1.6 times the molar amount of 1,4
-Butanediol is esterified by a conventional method, tetrabutyl titanate is added as a catalyst,
Polycondensation reaction is performed for 3 hours at 1 ° C and 1 torr
(B) was obtained. The obtained polyester (B) has an [η] of 0.6.
1, Tm 58 ° C., Tc 27 ° C., ΔHc 60 mJ / mg.

Using copolyester (A), thickness 630 μm
Non-oriented film is produced by a tenter simultaneous biaxial stretching machine at a stretching temperature of 95 ° C., three times in the longitudinal direction and 3.5 in the transverse direction.
The film was double-stretched to obtain a single-layer oriented film having a thickness of 72 μm. A bag-like material was prepared from this oriented film, and the polyester (B) was sealed inside the bag to form a molded product. This molded product was wound around a thermocouple and heat-treated at 150 ° C for 30 minutes. Then, it was deformed into a flat plate shape in hot water of 80 ° C., put in water of 20 ° C. to temporarily fix its form, and then immersed again in hot water of 80 ° C., the original shape was recovered.

Examples 2 to 5 and Comparative Examples 1 to 6 As copolyester A and polyester B, those shown in Table 1 were used and the same tests as in Example 1 were conducted.

The results of the above Examples and Comparative Examples are summarized in Table 1.

[0030]

[Table 1]

In Table 1, the symbols of acid component, diol component and polyester represent the following. TPA: terephthalic acid BD: 1,4-butanediol DDA: dodecanedioic acid ND: 1,9-nonanediol AA: adipic acid PD: 1,5-pentanediol AZA: azelaic acid EG: ethylene glycol SEA: sebacic acid EDA : Eicosane diacid PCL: Polycaprolactone IPA: Isophthalic acid PET: Polyethylene terephthalate PBT: Polybutylene terephthalate

[0032]

Industrial Applicability According to the present invention, there is provided a shape-memory polyester molded article having a heat generating property, which is suitable for packaging foods, clothing, sanitary materials and the like. The molded product of the present invention can be arbitrarily changed to its shape and uses a thermoplastic polymer that is repeatedly melted and solidified, so that the heat generation performance can be selected according to the application.

Claims (2)

[Claims] 1. A composition comprising two or more dicarboxylic acid components,
A copolyester A having a shape memory capacity of 10 to 80 ° C. and having a glass transition point of 10 to 80 ° C., which is composed mainly of a dicarboxylic acid component of which 70 mol% or more is an aromatic dicarboxylic acid and one or more kinds of aliphatic diol components, and a melting point. Is a polyester B having a glass transition temperature of less than the melting point of the copolyester A, a heat of crystallization of 10 mJ / mg or more when the temperature is lowered, and a latent heat change accompanying the phase change of melting and solidification. A shape-memory polyester molded product having heat generation, characterized in that polyester B is disposed inside thereof. 2. The polyester molded product according to claim 1, wherein the polyester B is a linear aliphatic polyester.