JPH02240135A - Shape memory resin - Google Patents

Abstract

PURPOSE:To provide a shape memory resin having an excellent shape memory property and can develop its property when it is heated or is brought into contact with water by using a block copolymer comprising a specified high- melting crystalline segment and a specified low-melting segment. CONSTITUTION:A polyester/polyester block copolymer comprising a high-melting crystalline segment (A) based on polybutylene terephthalate and a low-melting segment (B) based on polyethylene glycol, wherein the amount of component (B) is 60-95wt.% based on the block copolymer is produced by appropriately selecting the amount of component B, the number-average MW of the polyethylene glycol, etc., so that the obtained copolymer may have a transmittance >=15% in a molten state and a heat of fusion of a melting peak appearing in a temperature range of 0-65 deg.C in differential scanning calorimetry >= 0.5cal/g. This copolymer is used as a shape memory resin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a shape memory resin, particularly a new shape memory resin based on melt moldable thermoplastic polyester.

[Prior Art] Shape memory is a phenomenon in which a material remembers its original shape (at the time of molding) and returns to its original shape by heating even if it is deformed at low or high temperatures.

In recent years, several shape memory resins such as polynorbornene and transpolyisoprene having the above-mentioned phenomenon have been announced (Japanese Patent Application Laid-open Nos. 59-53528 and 62-8602).
Publication No. 5). These are cheaper than conventional shape memory alloys, and are attracting attention from the electronics, medical, automobile-related parts, and architectural fields due to their unique properties.

[Problems to be Solved by the Invention] However, in order for the above-mentioned shape memory resin to exhibit shape memory properties, it is necessary to make it have a significantly high degree of polymerization or to perform crosslinking.

Therefore, the melt viscosity becomes extremely high, high temperature and high pressure molding conditions are required, and the moldability of the resin is not necessarily satisfactory, as injection moldability is particularly low and recycling is difficult. I could not say it.

The present invention solves the above-mentioned problems of the prior art and aims to develop a molding resin that has excellent shape memory and is easy to melt mold.

[Means for Solving the Problem] The above-mentioned problem of the present invention is to provide a high melting point crystalline segment mainly composed of polybutylene terephthalate (hereinafter referred to as PBT) and polyethylene glycol (hereinafter referred to as PEG).
A polyester/polyether block copolymer composed of a low melting point segment mainly composed of
0% to 95% by weight, and has a light transmittance in a molten state (hereinafter simply referred to as light transmittance) of 15% or more, and a melting peak that occurs in the temperature range of 0°C to 65°C in a differential scanning calorimeter. The heat of fusion (hereinafter simply referred to as heat of fusion) is 0.
This problem can be solved by a shape memory resin characterized by having a Cal/9 or more.

First, the shape memory resin of the present invention will be explained.

That is, in the shape memory resin of the present invention, polybutylene terephthalate derived from terephthalic acid or its lower alkyl ester and 1,4-butanediol is used as the high melting point crystalline segment, and other substances are used as necessary. dicarboxylic acids and glycols can be copolymerized, but the preferred high melting point crystalline segment is P
The BT unit content is 70 mol% or more.

The dicarboxylic acids other than terephthalic acid or its lower alkyl ester used here include isophthalic acid, phthalic acid, 2.6-naphthalenedicarboxylic acid, 1.5-naphthalenedicarboxylic acid, 4.4'-diphenyldicarboxylic acid,
Aromatic dicarboxylic acids such as diphenoxyethane dicarboxylic acid, aliphatic dicarboxylic acids such as succinic acid, oxalic acid, adibic acid, sebacic acid, dodecanedioic acid, dimer acid, and 1,4-cyclohexane dicarboxylic acid. Examples include alicyclic dicarboxylic acids. and,
Lower alkyl esters, which are ester-forming derivatives of these dicarboxylic acids, are also preferably used, and a mixture of two or more of these can also be used.

In addition, glycols other than 1,4-butanediol include those having 2 to 12 carbon atoms, such as ethylene glycol, propylene glycol, 1,5-pentanediol, 1,6-hexanediol, neobentyl glycol, and cyclohexanedimethanol. Examples include aliphatic diols, alicyclic diols, and ethylene oxide adducts of bisphenol A, which can be used alone or as a mixture.

On the other hand, the low melting point segment is mainly composed of PEG, but for the purpose of modifying the resin, other polyalkylene glycols such as polytetramethylene glycol can be used in an amount of up to 20% by weight based on the PEG.

The copolymerization ratio of the above high melting point crystalline segment and low melting point segment is 60% of the low corrosion point segment to the total copolymer.
It is necessary to range from 65% to 90% by weight, preferably from 65% to 90% by weight. Low melting point segment amount is 6
If it is less than 0% by weight, the shape recovery ability when heated from low temperature to 1% temperature will be poor, and sufficient performance as a shape memory resin will not be obtained. In addition, if the content exceeds 95% by weight, the resulting resin's mechanical properties such as strength and elongation, as well as its elastic modulus when heated to high temperatures, become too low, making it unsuitable for use as a practical resin. The deterioration of characteristics becomes significant when

In addition, the resin of the present invention will not exhibit shape memory unless it exhibits a light transmittance of 15% or more, and even if it does exhibit some shape memory, it will be a resin with low mechanical properties such as strength and elongation and cannot be put to practical use. I don't get it. In other words, the light transmittance is an index of compatibility between the high melting point crystalline segment and the low melting point segment, and if the light transmittance is less than 15%, it is assumed that shape memory does not occur due to macro phase separation of both segments. Zareru.

Therefore, in order to obtain good shape memory properties, the light transmittance needs to be 15% or more, preferably 25% or more.

Furthermore, the resin of the present invention has a heat of fusion of Q.5ca+79, preferably 2.5ca+. Unless cal/9 or more is exhibited, shape memory properties will not be exhibited. That is, a block copolymer of a high melting point crystalline segment and a low melting point segment has a heat of fusion of 0. 5
If the Cal value is less than 79, the material is just an elastomer or a soft polymer, and it has no shape memory, or even if it does, it is extremely insufficient, and the shape that differs from that of the molded product at high temperatures can be achieved by lowering the temperature. Sometimes the ability to hold is extremely low.

The light transmittance and heat of fusion of the resin of the present invention are measured as follows.

Light transmittance (%): A sample approximately 1 m thick cut out from a polymer was set on a Mettler Hot Stage FP-52, and melt-pressed at 240°C until the thickness of the glass slide was 0.8 m.
After melting for 3 minutes, the light transmittance (%) is measured using a 50x optical microscope (manufactured by Nippon Kogaku Co., Ltd.) equipped with a photocell manufactured by Nihon Kagaku Engineering Co., Ltd.

Note that the light transmittance of the slide glass is set as 100% as a reference measurement value, and external causes such as light source fluctuations are corrected.

Heat of fusion (cat/9); according to DuPont thermal analysis system 1091, 0°C to 6
Measure the heat of fusion of the melting peak that occurs in a temperature range of 5°C.

Next, an example of a method for producing the resin of the present invention will be explained.

In other words, the shape memory resin of the present invention is a block copolymer of a high melting point crystalline segment mainly composed of PBT and a low melting point segment mainly composed of PEG, and the copolymerization ratio of the low melting point segment, the light transmission Conventionally known methods can be used to produce the block copolymer, except that the ratio and heat of fusion are within specific ranges.

For example, there is a method in which a lower alkyl ester of terephthalic acid, an excess amount of 1,4-butanediol, and PEG are heated in the presence of a catalyst to undergo a transesterification reaction, and the resulting product is polycondensed. Also terephthalic acid, an excess of 1,
A method in which 4-butanediol and PEG are heated in the presence of a catalyst to undergo an esterification reaction and then polycondensed, or a method in which PEG is added immediately before the start of the polycondensation reaction in the above reaction and polycondensation is carried out. be. PBT in advance
There is a method of preparing PEG in advance and adding PEG thereto to carry out a transesterification reaction.

At this time, a good example of setting the light transmittance and heat of fusion of the block copolymer within a predetermined range is to appropriately select the copolymerization ratio of the low melting point segment and the number average molecular weight of PEG.

That is, regarding the light transmittance, it is necessary to pay attention to the following points. The longer the PEG chain, the lower the compatibility with the high melting point crystalline segment (mainly composed of PBT), and when the PEG number average molecular weight is large, only the region with a large amount of PEG copolymerization becomes compatible. Therefore, the light transmittance decreases. In order to keep the number average molecular weight and copolymerization amount of PEG within the scope of the present invention, it is preferable that the PEG copolymerization amount satisfies the following.
Number average molecular weight of -200 [PEG copolymerization 11≦-60
It is 00.

Further, in order to keep the heat of fusion within the range of the present invention, it is necessary to ensure the chain length and copolymerization amount necessary for crystallization of the PEG chain. For example, when the number average molecular weight of PEG is small, the PEG component in the low melting point segment is increased, so the number average molecular weight of PEG + 25 [PEG copolymerization amount] ≧ 3
300 However, it is preferable that the PEG copolymerization satisfy the weight %. Preferably PEG
The number average molecular weight of +25 [PEG copolymerization amount]≧3500.

In addition, as part of the terephthalic acid component and 1,4-butanediol component, other dicarboxylic acids and their lower alkyl esters and glycols, or other polyalkylene glycols such as aromatic dicarboxylic acids, aliphatic dicarboxylic acids, etc. Acids, alicyclic dicarboxylic acids, lower alkyl esters thereof, aliphatic diols having 2 to 12 carbon atoms, alicyclic diols, ethylene oxide adducts of bisphenol A, or polytetramethylene glycol, as well as polycarboxylic acids. , polyfunctional hydroxy compounds, oxyacids, etc. can be copolymerized. In particular, the polyfunctional component acts effectively as a viscosity increasing component, and the amount of copolymerization in this case is preferably 3 mol % or less. Such polyfunctional components can include trimellitic acid, trimesic acid, biromellitic acid, penzophenonetetracanolebonic acid, butanetetracanolebonic acid, glycerin, pentaerythritol and their esters, acid anhydrides, and the like. .

In general, in the above-mentioned transesterification reaction or esterification reaction and polycondensation reaction, preferred catalysts include titanium compounds, particularly tetraalkyl titanates such as tetrabutyl titanate and tetraisopropyl titanate, titanium oxalate metal salts such as potassium titanium oxalate, etc. can be mentioned.

Other preferred catalysts include organic tin compounds such as dibutyltin oxide, dibutyltin laurate, and monobutyltin oxide, and weak acid salts of metals such as lead, magnesium, lithium, and manganese.

The above transesterification or esterification reaction is carried out for approximately 1
The polycondensation reaction is carried out at a temperature of 50 to 260°C under normal pressure or slightly reduced pressure, and the subsequent polycondensation reaction is carried out at a temperature of about 2
It is generally carried out at a temperature of 00 to 300°C. The desired copolymer can also be obtained by combining in-phase polymerization as necessary.

The above-mentioned block copolymer can contain heat-resistant and light-resistant stabilizers such as antioxidants, thermal decomposition inhibitors, and ultraviolet absorbers during polymerization or after polymerization and before molding. Examples of the heat stabilizer include 4,4'-bis(2,6-di-tert-butylphenol), 1,3,5-
Trimethyl-2.4.6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tetrakis[
Methylene-3(3,5-di-tert-butyl-4-hydroxyphenyl)probionate 1methane, N,N-hexamethylene-bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamic acid amide), etc. Various hindered phenols, aromatic amines such as N,N'-bis(β-naphthyl)-p-phenylenediamine, 4,4'-bis(4-α,α'-dimethylbenzyl)diphenylamine, dilauryl Examples include sulfur compounds such as thiodipioneate, phosphorus compounds, alkaline earth metal oxides, and the like. In addition, substituted penzophenone,
Examples include penzotriazoles and piperidine compounds such as bis(2,2,6,6,-tetramethyl-4-piveridine) sebacateya 4-penzoyloxy-2,2,6,6,-tetramethylpiveridine. be able to.

The block copolymer also contains hydrolysis resistance improvers, colorants (pigments, dyes), antistatic agents, conductive agents, flame retardants, reinforcing agents, fillers, lubricants, mold release agents, nucleating agents, plasticizers, It is also possible to optionally contain adhesion aids, adhesives, and the like.

[Example] Hereinafter, the present invention will be specifically explained with reference to Examples.

"Parts" and "%" in this example are "parts by weight" and "% by weight."

Example 1 According to theoretical calculation, PBT/PEG bolamer composition is 35/65%
34.9 parts of dimethyl terephthalate, 62.3 parts of PEG with a number average molecular weight of 3000, and 24.3 parts of 1,4-butanediol (relative to dimethyl terephthalate,
1.5 mole times) of the catalyst tetrabutyl titanate 0.1
5 parts together with a rectification column and a reaction vessel equipped with a stirrer,
Heating at about 210'C for 2 hours to reduce the theoretical amount of methanol to 95%.
% of methanol was distilled out of the system. Shun transferred this reaction product to a polymerization tank, “Irganox” 1010
Add 0.2 parts and raise the temperature in the system to 245 ° C.
It took 60 minutes to reduce the pressure from normal pressure to about 0. Polycondensation was carried out under the reduced pressure of 2 mtl (J) for 4 hours, and a transparent viscous polymer was obtained. It was discharged from the polymerization can as a gut of about 3 m, and after cooling with air blow, it was cut. The characteristic values of the obtained volima are shown in Table 1.

Next, in order to verify the shape memory property of the above polymer, the above polymer was heated to 200°C and made into a length of 10 cm and a diameter of 2! It was melt-molded into a M1 straight gut shape. This product was deformed in hot air at about 80°C, and then left to cool at room temperature. When the gut was left in a deformed state at room temperature for several days or more, and then placed in hot air at 80°C again, it was confirmed that the polymer according to this example instantly returned to the shape when molded. It was verified that it had shape memory properties.

Example 2 According to theoretical calculation, PBT/PEG polymer composition is 20/80%
17.0 parts of terephthal M, 14.7 parts of 1,4-butanediol (1.6 parts by mole relative to terephthalic acid), 0.08 parts of tetrabutyl titanate as a catalyst, and 0.06 parts of monobutyl tin oxide. The water is then charged into a reaction vessel equipped with a rectification column and a stirrer, and the temperature is gradually raised from 160°C to about 230°C to cause an esterification reaction, resulting in water,
The esterification reaction was carried out for 4 hours while the tetrahydrofuran was distilled out of the system to complete the reaction. Next, 78.5 parts of PEG with a number average molecular weight of 7000 was charged in advance, and the ester reaction product was transferred to a heated polymerization reactor, followed by 0.10 parts of tetrabutyl titanate and 10 parts of "Irganox".
10 0. 20 parts were added, the temperature in the system was raised to 245°C, the pressure was reduced from normal pressure to about 0.2MHg over 50 minutes, and when polycondensation was carried out under these conditions for 4 hours, an almost transparent viscous polymer was obtained. This was obtained and made into chips in the same manner as in Example 1.

Table 1 shows the characteristic values of the obtained volima.

Next, the shape memory property of the above polymer was verified in the same manner as in Example 1, and it was confirmed that the polymer according to this example also instantly returned to the shape at the time of molding, and had sufficient shape memory property.

Example 3, Comparative Examples 1 to 4 Based on theoretical calculations, PBT/PEG (number average molecular weight 1000
A polymer having the properties shown in Table 1 was obtained in the same manner as in Example 2, except that the raw materials were charged so that the polymer composition of 0) was 10/90%. Further, as a comparative example, a bolamer was obtained in the same manner as in Example 2, except that the number average molecular weight of PEG or the bolamer composition of PBT/PEG was changed. These characteristic values are summarized in Table 1.

Next, the shape memory property of the above polymer was verified in the same manner as in Example 1, and it was confirmed that the polymer according to Example 3 instantly returned to the shape at the time of molding, and had excellent shape memory property.

On the other hand, the polymers of Comparative Examples 1 to 4 exhibited almost no shape memory.

(Hereinafter, blank space) [Effects of the Invention] The shape memory resin of the present invention has excellent shape memory properties, and like conventional shape memory resins, it not only exhibits shape recovery properties when heated, but also exhibits shape recovery properties when heated. It has a unique ability to reveal its functionality when it comes into contact with moisture.

Furthermore, since the resin of the present invention is thermoplastic and has excellent moldability, it can be suitably used as a molding resin, elastomer, etc., for example, in the fields of electronics, medical, automobile-related parts, construction, etc. In addition, it can exhibit excellent performance in the fields of fibers, fabrics, nonwoven fabrics, sheets, etc.

Claims (1)

[Claims] A polyester/polyether block copolymer composed of a high melting point crystalline segment mainly composed of polybutylene terephthalate and a low melting point segment mainly composed of polyethylene glycol, wherein the copolymerized amount of the low melting point segment is 60% to 95% by weight based on block copolymer
% by weight, and the light transmittance in the molten state is 15% or more, and the heat of fusion of the melting peak that occurs in the temperature range of 0 ° C to 65 ° C in a differential scanning calorimeter is 0.5 cal / g or more. Characteristic shape memory resin.