JPWO2020045439A1 - A soft cross-linked polyester resin / film that exhibits self-adhesiveness, remoldability, and scratch repair properties, and its manufacturing method. - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crosslinked polyester resin having excellent transparency, adhesiveness, flexibility (elongability), strength (Young's modulus), remoldability and scratch repair property, and a multilayer crosslinked polyester resin film having a film shape thereof. Is to provide. SOLUTION: This is a polyester resin 5 containing a polymer main chain 1 containing an ester bond 2 at multiple points and a multipoint covalent crosslinked portion 3 containing an ester bond 2 and a free OH group 4, and the ester bond 2 and a carboxylic acid. It can be obtained by mixing a polyester resin raw material containing a large number of acid groups, a diepoxy cross-linking agent, and an ester exchange catalyst 6 and heating to cross-link.

Description

The present invention relates to a soft crosslinked polyester resin / film exhibiting self-adhesiveness, remoldability, and scratch repair property, a soft multilayer crosslinked film, and a method for producing the same.

Since the bond-exchange type dynamic covalent bond cross-linked film can bond the films to each other without using an adhesive, it is possible to suppress the elution of foreign substances and residual solvents caused by the adhesive, resulting in a film with excellent safety. sell.

Conventional covalently bonded crosslinked films have poor reworkability and adhesiveness due to the irreversibility of covalently bonded crosslinked points. On the other hand, a film subjected to physical cross-linking (cross-linking by a crystal domain or a glass-like domain) can be reprocessed and adhered by heat, but has problems such as low water resistance, low solvent resistance, and low transparency.

Further, the conventional covalently bonded crosslinked elastomer has no remolding processability or repairability due to the irreversibility of the covalently bonded crosslinked point. On the other hand, elastomers that have undergone physical cross-linking (cross-linking with crystalline domains or glassy domains) can be remolded by heat and repaired from scratches on the surface, but have low water resistance, low solvent resistance, and low transparency. There is a problem.

Patent Document 1 describes a laminate of a polyester resin film and a polyolefin resin film by heating. Further, Patent Document 2 describes a laminate having at least one layer of polyester-based film.

The heating of the laminate of Patent Document 1 is mainly by electron beam irradiation and contains a polyolefin resin film, so that the transparency is inferior to that of the laminate made of polyester resin films. On the other hand, in the polyester film described in Patent Document 2, the total of one or more monomer components that can be amorphous components among all the monomer components is 12 mol% or more and 30 mol% or less, so that the polyester film is at room temperature. Inferior in flexibility and toughness. Further, although Non-Patent Document 1 describes a method for preparing a crosslinked material into which a bond exchange reaction has been introduced, there is no description regarding the adhesive properties of a film-like sample.

Patent Document 3 describes a polymer chain of a self-healing resin composition containing a polyester resin, an organic titanium compound, 1,4-butylene glycol, bis (2-hydroxyethyl) terephthalate, or dimethyl phthalate. It is stated that it can be combined to perform self-repair and prevent deterioration. However, the self-repair is based on the evaluation based on the average molecular weight of the composition, and there is no description about the scratches on the composition.

Further, Patent Document 4 includes an amorphous polymer X having a dungling chain and a crosslinked structure, and an amorphous polymer Y having a glass transition temperature of room temperature or higher as measured by dynamic viscoelasticity. A self-healing resin body characterized by this is disclosed. However, the evaluation of scratches on the self-healing resin body is not clear, and there is no description about the remolding processability of the self-healing resin body.

On the other hand, Non-Patent Document 1 does not describe the production of a bond-exchange type dynamically covalently bonded crosslinked film that exhibits flexibility at room temperature. In addition, there is no description regarding self-adhesiveness and repairability of surface scratches.
Further, although Non-Patent Document 2 describes the remoldability, it shows only an elongation rate of about 5%, and does not show the property as a flexible resin. In addition, there is no description about repairing surface scratches or self-adhesiveness. Although Non-Patent Document 3 describes the production of a bond-exchange type dynamic covalent bond-crosslinked film in which a catalyst is contained during cross-linking, a bond-exchange type by immersing a non-catalyst-containing sample in a catalyst-containing solution. There is no description regarding the production of dynamic covalent crosslinked films.

Japanese Unexamined Patent Publication No. 2012-254593 Re-table 2014-175313 Japanese Unexamined Patent Publication No. 2005-023166 Japanese Unexamined Patent Publication No. 2010-260979

Damien Montarnal, M. Capelot, F. Tournilhac, Ludwik Leibler, Science, 2011, Vol.334, Issue 6058, 965-968. Jacob P. Brutman, Paula A. Delgado, and Marc A. Hillmyer, ACS Macro Letters, 2014, Vol. 3, Issue 7, 607? 610. Mikihiro Hayashi, et al., Polymer Chemistry. 10 (16) 2047 --2056, 2019.

The subject of the present invention is a soft crosslinked polyester resin having excellent transparency, crosslinking, flexibility (elongability), strength (Young rate), remoldability, and scratch repairability, which solves the above problems. It is to provide a film, that is, a soft crosslinked polyester resin / film. Furthermore, it is an object of the present invention to provide a soft multilayer crosslinked polyester resin film having a film shape, that is, a soft multilayer crosslinked polyester film.

(1) A polyester resin containing a polymer main chain containing multiple ester bonds and a multi-point covalently bonded crosslinked portion containing an ester bond and a free OH group (that is, a free OH group is contained at multiple points in the network structure). Cross-linked polyester resin) and a cross-linked polyester resin containing an ester exchange catalyst.
(2) The crosslinked polyester resin according to (1), which is obtained by mixing a polyester resin raw material containing an ester bond and a carboxylic acid group at multiple points, a diepoxy crosslinking agent, and the transesterification catalyst, and heating and crosslinking the mixture. Is.
(3) The crosslinked polyester resin according to (2), wherein the polyester resin raw material has an average molecular weight of 8000 or more, and the polyester resin raw material has 100 or more polyester bonds.
The average molecular weight is a number average molecular weight.
(4) The ratio of the carboxylic acid group of the polyester resin raw material is 10 mol% to 50 mol% with respect to the ester group of the polyester resin raw material, and the carboxylic acid group of the polyester resin raw material and the diepoxy in the cross-linking reaction. The crosslinked polyester resin according to (2) or (3), wherein the ratio of the crosslinked epoxy group (carboxylic acid group: epoxy group) is 1: 0.5 to 1: 1.5.
(5) The molar ratio of the transesterification catalyst to the free OH group in the network structure after cross-linking (free OH group: transesterification catalyst epoxy group) is 1: 0.1 to 1: 0.4 (2) to (1) to (1). The crosslinked polyester resin according to 4).
(6) This is a method for producing a crosslinked polyester resin obtained by mixing a polyester resin raw material containing an ester bond and a carboxylic acid group at a large number of points, a diepoxy crosslinking agent, and a transesterification catalyst, and heating and crosslinking the mixture.
(7) The crosslinked polyester resin is the crosslinked polyester resin according to any one of (1) to (5), which has a film shape.
(8) A multilayer crosslinked polyester resin film including a portion in which the film-shaped crosslinked polyester resin according to (7) is adhered and laminated.
(9) The package is characterized in that the multilayer crosslinked polyester crosslinked resin film according to (8) is used at least partially.
(10) A method for producing a multilayer crosslinked polyester crosslinked resin film in which at least a part of the film-shaped crosslinked polyester resin according to (7) is pressed at a high temperature.
(11) A method for producing a remolded crosslinked polyester resin, which comprises a deformation step in which the crosslinked polyester resin according to (7) is deformed in its shape and a heat treatment step in which the crosslinked polyester resin is subsequently treated by heat.
(12) A method for producing a crosslinked polyester resin in which the scratches have been repaired, which comprises a step of damaging the surface of the crosslinked polyester resin according to (7) and then a heat treatment step of treating the crosslinked polyester resin with heat.
(13) The ester exchange catalyst is a crosslinked polyester resin that does not contain an ester exchange catalyst and is obtained by mixing a polyester resin raw material containing an ester bond and a carboxylic acid group at multiple points with a diepoxy crosslinking agent and heating and crosslinking. It is a method for producing a crosslinked polyester resin obtained by immersing it in a solution containing.

The cross-linked polyester resin according to the present invention has high transparency and high strength flexibility at room temperature due to the introduced "dynamic" covalent bond cross-linking that allows bond exchange at high temperatures, above or above the bond exchange activation temperature. In the vicinity, reworking and adhesion between films are possible. Further, the bond exchange catalyst used in the present invention is also inexpensive, various catalysts can be used, the cross-linking reaction itself is short, and it is convenient for industrialization.
Further, the remolding processability of the crosslinked polyester resin has the effect of allowing free shape adjustment and thinning after the crosslinking reaction, and the scratch repairing property has the effect of enabling semi-permanent use.

It is a figure which showed typically the crosslinked polyester resin which is one Embodiment of this invention. It is a figure which showed the molded product (4 cm × 4 cm, thickness 0.1 cm) of a square crosslinked polyester resin. It is a figure which shows an example of the combination of the manufacturing raw material of a crosslinked polyester resin, and has shown (A) a polyester resin raw material containing a carboxylic acid group at a plurality of points, (B) a diepoxy crosslinking agent, and (C) a transesterification catalyst, respectively. It is a figure. It is a figure which shows typically the mode in which (A) two crosslinked polyester resin films are laminated to form (B) a two-layer crosslinked polyester resin film. It is a figure which shows typically (A) before reaction and (B) after reaction about the transesterification reaction between crosslinked polyester resins. It is a figure which showed the structural formula of the polyester resin raw material which melt-condensated adipic acid, thioannic acid and pentanediol. It is a figure which showed the chart example about the definition of the maximum stress and the elongation at break using Example 3. FIG. It is a figure which showed (A) the state which overlapped a part of each of two crosslinked polyester resin films, and (B) the state where one crosslinked polyester resin film was bent. It is the figure which showed (A) the two-layer crosslinked polyester resin film which was pressed and adhered at a high temperature, and (B) the two-layer crosslinked polyester resin film which was partially broken. It is a figure which showed the method of obtaining the softening temperature of a crosslinked polyester resin film (Examples 4 to 6). It is a figure which showed the crosslinked polyester resin film. It is a figure which showed the cross-linked polyester resin film wound around the spartel and fixed both ends to the spartel, and the cross-linked polyester resin film remolded by (B) (A), respectively. (A) The surface of the crosslinked polyester resin film containing scratches (enlarged view), and (B) (A) the surface of the crosslinked polyester resin film (enlarged view) in which the scratches disappeared by subjecting the heat treatment step, respectively. be. It is a schematic diagram of the manufacturing method of the crosslinked polyester resin obtained by immersing a crosslinked polyester resin (molded product) which does not contain a transesterification catalyst in a solution containing a transesterification catalyst. Linear expansion rate measurement for a crosslinked polyester resin (film) containing no transesterification catalyst (zinc acetate) immersed in a solution containing 0 (no catalyst), 2.5 mg / mL, 5 mg / mL, 10 mg / mL. It is a figure which showed the result. It is a figure which showed the softening temperature about the crosslinked polyester resin (film) which did not contain a transesterification catalyst which was immersed in the solution which contained the transesterification catalyst (zinc acetate) 2.5mg / mL, 5mg / mL, 10mg / mL.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments, and changes, modifications, and improvements can be made without departing from the scope of the invention.

As shown in FIG. 1, the crosslinked polyester resin (7) of the present invention has a polymer main chain (1) containing an ester bond (2) at multiple points, an ester bond (2), and a free OH group (4). Includes a polyester resin (5) containing a multipoint covalent crosslinked moiety (3), and an ester exchange catalyst (6). The free OH group (free hydroxyl group) (4) is a hydroxyl group that is not contained in the ester bond (2) of the polymer main chain (1) and has not reacted with any functional group. In the crosslinked polyester resin containing many free OH groups in the network structure, the polymer main chain (1) contains many ester bonds and the covalently bonded crosslinked portion (3) contains many free OH groups (4). That is, the free OH group (4) is partially contained in the polymer crosslinked network.
As will be described later, the free OH group (4) attacks the C-0 bond of one of the many ester bonds existing in the vicinity by the action of the transesterification catalyst (6) existing in the vicinity thereof. By doing so, a transesterification reaction occurs. Then, when the transesterification reaction proceeds between the surfaces of the two overlapping films under high temperature and pressing, adhesion occurs due to the newly formed bond.

The average molecular weight of the polyester resin raw material is preferably 8000 (g / mol) or more, more preferably 15000 (g / mol) or more, from the viewpoint of resin strength and heat resistance. The number of ester bonds is preferably 100 or more, more preferably 200 or more, in order to achieve the above molecular weight.

The proportion of free OH groups is preferably 10 mol% to 50 mol%, preferably 15 mol% to 15 mol% with respect to the ester groups in the polyester resin raw material (polymer) from the viewpoint of ease of polymer sample synthesis and flexibility at room temperature. 40 mol% is more preferable. The proportion of the transesterification catalyst is preferably 10 mol% to 40 mol%, more preferably 15 mol% to 30 mol% with respect to the free hydroxyl group from the viewpoint of the mechanical strength of the resin and the uniformity of the sample.

The molded product made of crosslinked polyester resin had transparency. The molded product (8) in FIG. 2 is a square (4 cm × 4 cm, thickness 0.1 cm), and the molded product (8) is placed on a white paper with “NI tech” written in black. However, the letters "NI tech" looked as clear as the part where the molded product (8) was not placed.

An example of a method for producing the crosslinked polyester resin (7) will be described with reference to FIG. A diepoxy cross-linking agent (B) is mixed with a liquid polyester resin raw material (A) containing a carboxylic acid group at multiple points, a transesterification catalyst (C) is added, and a cross-linking reaction is carried out via an epoxy ring-opening reaction. rice field.

As the polyester resin raw material (A), a polyester containing a carboxylic acid group at many points is preferably used. As a constituent monomer of polyester which is a precursor of the polyester resin raw material (A), 1,5-pentanediol and 1,6-hexanediol as diol molecules and adipic acid and glutaric acid as dicarboxylic acid molecules are in the side chain. As the dicarboxylic acid molecule containing a reactive group, thioapple acid is preferably used, in which case a polyester precursor containing a thiol group at multiple points in the side chain can be obtained by melt polycondensation. When the precursor is reacted with, for example, acrylic acid, a polyester resin raw material (A) containing carboxylic acid at multiple points in the side chain can be obtained by a Michael addition reaction between the thiol group and the double bond of acrylic acid.

As the diepoxy cross-linking agent (B), 1,4-butanediol diglycidyl ether, 1,2,7,8-diepoxy octane, neopentyl glycol diglycidyl ether and the like are preferably used. On the other hand, as the transesterification catalyst (C), zinc acetate, triphenylphosphine, 1,5,7-triazabicyclo [4.4.0] deca-5-ene and the like are preferably used.

The mixing ratio of the polyester resin raw material (A) and the diepoxide cross-linking agent (B) is based on the functional group molar ratio between the side chain carboxylic acid of the polyester resin raw material (A) and the epoxy group of the diepoxide cross-linking agent (B). Can be determined. From the viewpoint of cross-linking reaction efficiency, the carboxylic acid group: epoxy group is preferably 1: 0.5 to 1: 1.5, more preferably 1: 0.8 to 1: 1.2. As for the mixing ratio of the transesterification catalyst (C) to the free hydroxyl group, the molar ratio of the free hydroxyl group: transesterification catalyst is preferably 1: 0.1 to 1: 0.4 from the viewpoint of catalytic activity efficiency. : 0.15 to 1: 0.3 is more preferable.

Regarding the conditions of the polycondensation reaction performed in the preparation of the carboxylic acid group-containing polyester resin, from the viewpoint of uniform mixing of the constituent monomers and from the viewpoint of suppressing the coupling reaction between the thiol groups during the polycondensation, 70 ° C. to 120 ° C. ° C is preferable, and 80 ° C to 100 ° C is more preferable. The reaction time is preferably 10 hr or more, more preferably 20 hr or more, from the viewpoint of obtaining a sufficient high molecular weight substance. The method for forming a crosslinked product using a carboxylic acid group-containing polyester resin raw material obtained by polycondensation and a subsequent Michael reaction, a diepoxy crosslinker, and a transesterification catalyst can be carried out using a Teflon (registered trademark) type or a glass type. In the cross-linking reaction, 4 hr or more is preferable at 120 ° C. to 160 ° C. from the viewpoint of promoting sufficient cross-linking and preventing thermal decomposition of the sample.

The shape of the molded product made of the crosslinked polyester resin can be various, but the film shape is preferable from the viewpoint of maintaining a sufficient adhesive area. As for the film shape, for example, the thickness is preferably 0.1 mm to 3 mm from the viewpoint of the mechanical strength of the resin sample and the smoothness of the surface.

FIG. 4 shows an embodiment in which (A) two crosslinked polyester resin films (20, 21) are laminated to form (B) a two-layer crosslinked polyester resin film (30). Adhesion is performed by an ester exchange reaction in which each free hydroxyl group contained in the crosslinked polyester resin films (20, 21) attacks the C-0 bond of the ester bond of the crosslinked polyester resin film other than the crosslinked polyester resin film containing each. The layer (31) is formed. The transesterification reaction occurs by a transesterification catalyst existing near a free hydroxyl group and heating under pressure suitable for its catalytic action.

FIG. 5 schematically shows a transesterification reaction between crosslinked polyester resins forming an adhesive layer (31A). The polymer main chains 1A and 1B and the covalently bonded crosslinked portion 3A are contained in the same crosslinked polyester resin, and the polymer main chain 1C is contained in another same crosslinked polyester resin. The free OH group contained in the covalently bonded crosslinked portion 3A attacks the C-0 bond of the polyester bond of the polymer main chain 1C by the action of a transesterification catalyst under pressure. Then, the covalent bond cross-linked portion 3A and the polymer main chain 1C are bonded via a free 0 (oxygen atom), and the covalent bond cross-linked portion 3A and the polymer main chain 1C are bonded to the branched polymer main chain ( The covalently bonded crosslinked portion 3A is bonded to a part of the polymer main chain 1C), and the adhesive layer 31A is formed. On the other hand, the C-0 bond of the polyester bond of the polymer main chain 1C is cleaved to generate the polymer main chain terminal portion 1D having a free OH group at the end. It can be interpreted that the polymer main chain terminal 1D is also included in the adhesive layer 31A.

Regarding the production conditions of the multilayer crosslinked polyester resin film, the temperature is preferably 140 ° C. to 200 ° C. from the viewpoint of the bond exchange activation temperature and the heat resistance of the resin. The pressing is preferably 100 Pa or more, more preferably 1 kPa or more, from the viewpoint of promoting bond exchange between the surfaces. Further, in order to prevent the sample from breaking, 100 MPa or less is preferable. The pressing time is preferably 2 hr, more preferably 4 hr, in order to obtain good adhesive strength, that is, to obtain a sufficient number of molecular chains that have been bonded and exchanged across the surfaces.

(Preparation of polyester resin raw material)
First, a polyester obtained by melt-condensation polymerizing adipic acid, thiomalic acid and 1,5-pentanediol was synthesized. Then, a polyester resin raw material containing a carboxylic acid group at multiple points in the side chain was prepared by Michael addition between the thiol group of thioannic acid and the double bond portion of acrylic acid. Table 1 shows the prepared polyester resin raw materials.
In Table 1, Code: PE-X / Y / Z is carboxylic acid-added thioannic acid (X) / adipic acid (Y) / 1,5-pentanediol (Z), and _NCOOH is per high molecular chain. The number of carboxylic acid groups and the COOH / Ester ratio were the ratio of carboxylic acid groups / ester bonds per polymer chain. Further, X, Y, and Z represent the molar ratios of the constituent monomers in the polymer chain determined by 1H-NMR (see unit molar ratio).

In Table 1, the number average molecular weight (Mn) and the molecular weight distribution (PDI) were measured by GPC using a Shodex KD803 with a 804 column, a Tosoh DP8020 pump system, and an RI detector (Tosoh RI-8020). As the eluent, DMF to which LiBr (0.05 wt%) was added was used.

(Crosslinked polyester resin film, Examples 1 to 6, Comparative Example 1)
The crosslinked polyester resin film 22 shown in FIG. 8A was produced as follows.
The polyester resin raw material 10, a diepoxy cross-linking agent (1,4-butanediol diglycidyl ether) and a transesterification catalyst (zinc acetate) were dissolved in chloroform, respectively.
The solution was mixed in a Teflon® mold and then the solvent was volatilized on a heater at 40 ° C. This mixed sample was heated at a temperature of 120 ° C. for 4 hours under a vacuum to obtain a crosslinked resin. The obtained crosslinked resin was cut into a film using a cutter to have a width of 4 mm, a thickness of 0.3 mm, and a length of about 15 mm (Example 1). Examples 2 and 3 were obtained in the same manner as in Example 1 except that the polyester resin raw materials 11 and 12 were used instead of the polyester resin raw material 10. In Examples 1 to 3, the mol ratio of the carboxylic acid: epoxy group was 1: 1 and the ratio of the transesterification catalyst was 20 mol% with respect to the free hydroxyl group.

Further, using the polyester resin raw material 10, the crosslinked resin obtained in the same manner as in Example 1 was cut into a film using a cutter to make a width: 4 mm, a thickness: 0.15 mm, and a length: about 15 mm. (Example 4) was obtained. Examples 5 and 6 were obtained in the same manner as in Example 4 except that the polyester resin raw materials 11 and 12 were used instead of the polyester resin raw material 10. In Examples 4 to 6, the mol ratio of the carboxylic acid: epoxy group was 1: 1 and the ratio of the transesterification catalyst was 20 mol% with respect to the free hydroxyl group.

Further, the crosslinked resin obtained in the same manner as in Example 1 except that the polyester resin raw material 11 was used instead of the polyester resin raw material 10 was cut into a film shape using a cutter, and the width: 4 mm and the thickness: 0. Two crosslinked polyester resin fills 22 (Example 7) having a length of 5 mm and a length of 25 mm were obtained. On the other hand, in Example 7, the transesterification catalyst was eluted by immersing the transesterification catalyst in chloroform, which dissolves the transesterification catalyst well, to prepare a polyester resin film (Comparative Example 1) containing no transesterification catalyst.

(Tensile test)
Using Examples 1 to 3, a tensile test was performed as follows. The results are shown in Table 2. In addition, FIG. 7 shows a chart regarding the definitions of maximum stress and elongation at break using Example 3.
Measurements were carried out using SHIMADZU AG-X plus at room temperature and a tensile speed of 10 mm / min. Young's modulus (MPa) was determined as stress (MPa) / displacement (%) from the stress at the time of 5% deformation. The maximum stress (MPa) was determined as the maximum stress measured before breaking. The elongation at break was determined as the sample displacement (%) at break. The initial distance between jigs was about 15 mm.

From Table 2, it can be seen that the crosslinked polyester resin film obtained in this molecular design has sufficient flexibility at room temperature (break elongation >> 20%), although it has introduced bond exchange type crosslinking. In addition, since the carboxylic acid groups were introduced at multiple points in the lateral difference, a sufficient Young's modulus as a flexible film was shown (>> 1 MPa). The Young's modulus tends to be higher in the sample having a higher COOH / Ester ratio, suggesting that the crosslink density in the network structure can be controlled by the COOH / Ester ratio.
In the above tensile test, the Young's modulus is preferably 0.10.1 MPa to 100 MPa, more preferably 1 MPa to 10 MPa, from the viewpoint of maintaining strength and flexibility. Further, the elongation at break is preferably 10% to 500%, more preferably 30% to 200%, from the viewpoint of maintaining good elasticity.

As shown in FIG. 8 (A), it was confirmed from Example 7 picked with the tweezers 40 that it had transparency.

As shown in FIG. 8 (B), even if both ends are bent 180 ° and the both ends are aligned with each other in the seventh embodiment, the two ends are not broken, and when the bending force is released, the original state is restored. rice field. As a result, it was found that Example 7 had high strength and flexibility at room temperature. Having such high strength flexibility at room temperature can be estimated from the fact that the Tg (glass transition temperature) of Example 7 is about −30 ° C., which is extremely lower than room temperature.

(Softening characteristics)
Using Examples 4 to 6 as samples, the softening characteristics were measured as follows. The softening temperature was determined as shown in FIG. 10 (in FIG. 10, L represents the sample length under measurement and L _{100 ° C.} represents the initial sample length at 100 ° C.), and the results are shown in Table 3.
Using HITACHI TMA7100, it was determined from the inflection point of the change in the coefficient of linear expansion of the sample from room temperature to 230 ° C. The measurement was performed in a nitrogen gas atmosphere and under a slightly constant tension (30 mN) to prevent the sample from bending. The initial distance between jigs was about 15 mm. also

From Table 3, it can be seen that the cross-linked polyester resin into which the bond-exchange type dynamic covalent bond cross-linking has been introduced exhibits specific softening properties at high temperatures. A normal amorphous crosslinked resin does not show a softening point at a high temperature other than the glass transition temperature and the decomposition temperature. Since the samples of Examples 4, 5 and 6 have a glass transition temperature of about -30 ° C and a decomposition temperature of 200 ° C or higher, the softening property is that the bond exchange between the ester bond and the free OH group is activated. It can be said that it is due to that. Further, the softening temperature is lower as the sample has a higher COOH / Ester ratio. The reason for this is that the higher the COOH / Ester ratio of the sample, the higher the introduction rate of the "free OH group" that is responsible for the transesterification reaction, and the bond exchange is more likely to be activated at a lower temperature. From this result, it is suggested that the present polyester crosslinked resin can be controlled by the COOH / Ester ratio.
In the above softening characteristics, the softening temperature is preferably 100 ° C. to 250 ° C., more preferably 120 ° C. to 200 ° C. from the viewpoint of maintaining thermal stability and preventing thermal decomposition of the polymer chain.

(Two-layer crosslinked polyester resin film, Example 8, Comparative Example 2)
As shown in FIG. 8A, two sheets of Example 7 were used, and one ends thereof were overlapped with each other, the temperature was 140 ° C., the pressing time was 400 kPa, and the pressing time was 4 hr. A two-layer crosslinked polyester resin film 30 (Example 8) including a portion was produced.
On the other hand, an attempt was made to produce a two-layer polyester resin film using two Comparative Examples 1 in the same manner as in Example 7, but Comparative Examples 1 did not adhere to each other and the two-layer polyester resin film could not be produced. (Comparative example 2).

As shown in FIG. 9A, when both ends of the two-layer crosslinked polyester resin film 30 were picked and pulled, as shown in FIG. 9B, the laminated portion 36 did not break and the laminated portion was formed. A multilayer crosslinked polyester resin film 35 having a broken end portion was formed by breaking at a portion other than 36. From this, it was found that the tensile strength at the two-layer portion 36, that is, the adhesive portion was large.

For example, a packaging body may be formed in which a predetermined space is formed between two film-shaped crosslinked polyester resins, and the crosslinked polyester resins are bonded to each other so as to wrap a useful object in the predetermined space. ..

(Reformability, Example 9)
Using Example 1 (FIG. 11), as shown in FIG. 12 (A), Example 1 was subjected to a deformation step. That is, Example 1 was wound around a spatula 41, both ends thereof were taped, and fixed to the spatula 41 to obtain a deformed crosslinked polyester resin film 23. Then, the deformed crosslinked polyester resin film 23 was subjected to a heat treatment step of being treated by heat. As a heat treatment step, the mixture was left at a high temperature (160 ° C.) for 2 hours and allowed to cool to room temperature. After allowing to cool, the deformed crosslinked polyester resin film 23 was removed from the spatula 41. Then, as shown in FIG. 12B, the deformed crosslinked polyester resin film 23 became a remolded crosslinked polyester resin film 24 in which the wound state was maintained (Example 9). ..
It was presumed that the cross-linked polyester resin film was remolded because transesterification was activated at high temperatures and a new equilibrium network structure was immobilized during cooling.

As the heat treatment step, the temperature (high temperature) applied to the deformed crosslinked polyester resin film is preferably 150 ° C. or higher, more preferably 170 ° C. or higher, from the viewpoint of the bond exchange activation temperature. On the other hand, from the viewpoint of decomposition of the polymer chain, 200 ° C. or lower is preferable.
Further, the time for applying the temperature is preferably 1 hour or more, more preferably 2 hours or more, from the viewpoint of advancing sufficient bond exchange. The deformation of the crosslinked polyester resin film has various aspects other than the above, such as bending, rolling, compressing, and stretching.

(Scratch repairability, Example 10)
Example 1 (FIG. 11) was subjected to a step of receiving a scratch 50 on the surface thereof as shown in FIG. 13 (A) using a cutter (thickness of a cutter blade: 0.1 mm). The scratch 50 was observed on the surface of the crosslinked polyester resin film 25 including the scratch 50 using a microscope, and an image thereof was acquired. The conditions for microscopic observation were a magnification of 20 times and a nitrogen atmosphere.
From FIG. 13 (A), the length of the scratch 50 exceeds about 550 μm, and it is confirmed that the scratch 50 is cut into the surface by the blade of the cutter, and the depth of the scratch 50 is about 0.1 mm. there were.

After acquiring the image, the crosslinked polyester resin film 25 was subjected to a heat treatment step of being treated by heat. As a heat treatment step, the mixture was left at a high temperature (180 ° C.) for 10 minutes and allowed to cool to room temperature. When the heat treatment step was performed, as shown in FIG. 13B, the scratches 50 disappeared cleanly, and the crosslinked polyester resin film 26 having no scratches 50 on the surface was obtained (Example 10).
It was presumed that the scratches disappeared, that is, the crosslinked polyester resin film had scratch repair properties, because the bond exchange was activated at high temperature and the rearrangement of the molecular chains near the surface was promoted.

As the heat treatment step, the temperature (high temperature) applied to the crosslinked polyester resin film including scratches is preferably 150 ° C. or higher, more preferably 170 ° C. or higher, from the viewpoint of the bond exchange activation temperature. On the other hand, from the viewpoint of decomposition of the polymer chain, 200 ° C. or lower is preferable. Further, the time for applying the temperature is preferably 10 minutes or more, more preferably 20 minutes or more, from the viewpoint of advancing sufficient bond exchange.

(Manufacture of crosslinked polyester resin by immersing in transesterification catalyst solution)
FIG. 14 shows an outline of a method for producing a crosslinked polyester resin obtained by immersing a crosslinked polyester resin containing no transesterification catalyst in a solution containing a transesterification catalyst. A molded product 8A made of a crosslinked polyester resin can be obtained by immersing the molded product 9 made of a crosslinked polyester resin containing no transesterification catalyst in the transesterification catalyst solution 60 for a certain period of time.

In FIG. 14, the molded product 9 is shown as a crosslinked polyester resin that does not contain a transesterification catalyst, but the shape may be various shapes including a film shape. As the ester exchange catalyst, zinc acetate or acetylacetone zinc (II) salt is preferable from the viewpoint of solubility, and as the solution containing the ester exchange catalyst, chloroform or tetrahydrofuran is preferable from the viewpoint of solubility and volatile easiness. When the ester exchange catalyst is zinc acetate and the solution is chloroform, zinc acetate is dissolved in chloroform, and it is preferable that the solution is in such a dissolved state from the viewpoint of permeability to the sample. On the other hand, from the viewpoint of catalytic activity, the transesterification catalyst may be in a dispersed state in the solution.

The concentration of the transesterification catalyst is preferably 1.0 mg / mL or more, more preferably 2.5 mg / mL or more, from the viewpoint of catalytic activity. Further, from the viewpoint of solubility in a solvent, 20 mg / mL or less is preferable, and 10 mg / mL or less is more preferable. The time for immersing the crosslinked polyester resin containing no transesterification catalyst in the transesterification catalyst solution is preferably 6 hours or more, more preferably 12 hours or more, from the viewpoint of equilibrium swelling degree.

(Cross-linked resin (film-like piece) not containing a transesterification catalyst, Reference Comparative Examples 1 to 4)
The polyester resin raw material 10 and the diepoxy cross-linking agent (1,4-butanediol diglycidyl ether) were dissolved in chloroform, respectively. The solution was mixed in a Teflon® mold and then the solvent was volatilized on a heater at 40 ° C. This mixed sample was heated at a temperature of 120 ° C. for 4 hours under vacuum to obtain a crosslinked resin containing no transesterification catalyst. The obtained crosslinked resin containing no transesterification catalyst was cut into a film using a cutter, and 4 sheets (Reference Comparative Examples 1 to 4) were formed with a width of 4 mm, a thickness of 0.3 mm, and a length of about 15 mm. Obtained. In Reference Comparative Examples 1 to 4, the mol ratio of the carboxylic acid: epoxy group was 1: 1.

(Crosslinked polyester resin (film-like piece), Comparative Example 3, Examples 11 to 13)
A film-like piece of Reference Comparative Examples 1 to 4 was immersed in a chloroform solution having zinc acetate concentrations of 0 mg / mL, 2.5 mg / mL, 5 mg / mL, and 10 mg / mL for 12 hours, respectively, to form a film. A piece of crosslinked polyester resin (Comparative Example 3, Examples 11 to 13) was obtained. Comparative Example 3 (zinc acetate concentration 0 mg / mL), Example 11 (zinc acetate concentration 2.5 mg / mL), Example 12 (zinc acetate concentration 5 mg / mL), Example 13 (zinc acetate concentration 10 mg) Each linear expansion rate was measured for / mL).

(Measurement of coefficient of linear expansion)
The linear expansion rate is measured by raising the temperature (100 ° C. to 200 ° C.) of the film-shaped piece with a constant weak stress (30 mN) and measuring the change in the sample length of the film-shaped piece. The axis is the temperature, and the vertical axis is L (film length) / film length at _{100 ° C.} L 100 ° C. (film length at 100 ° C.) is shown in FIG.
From FIG. 15, it was found that in Examples 11 to 13, the sample length rapidly increased or softened at a high temperature, and the degree of the increase increased toward Examples 11 to 13, that is, as the zinc acetate concentration increased. .. The increasing tendency was presumed to be due to transesterification activation at high temperatures.

(Softening temperature)
FIG. 16 is created based on FIG. That is, the difference (ΔLexp-const) between the actual sample length change (solid line in FIG. 15) and the constant sample length change (dotted line in FIG. 15) is obtained, and the softening temperature defined by the difference = 0.005 (dotted line in FIG. 15). ) Was determined, and it was found that the softening temperature decreased toward Examples 11 to 13, that is, as the zinc acetate concentration increased.
By softening in this way, the crosslinked polyester resin is imparted with remoldability and reworkability, which is advantageous for, for example, thinning of the film and fine processing of the crosslinked resin.

It can be used as a crosslinked polyester resin that forms a predetermined space and forms a package capable of wrapping a useful object in the predetermined space.

1, 1A, 1B, 1C, 1D: Polymer main chain 2: Ester bond 3, 3A: Covalent bond Cross-linked portion 4: Free OH group (hydroxyl group)
5: Polyester resin 6, 6A: Ester exchange catalyst 7: Crosslinked polyester resin 8: Molded product made of crosslinked polyester resin 8A: Molded product made of crosslinked polyester resin 9: Molded product made of crosslinked polyester resin not containing ester exchange catalyst 10,11, 12: Polyester resin raw materials 20, 21, 22: Cross-linked polyester resin film 23: Deformed cross-linked polyester resin film 24: Remolded cross-linked polyester resin film 25: Cross-linked polyester resin film having scratches on the surface 26: After heat treatment Cross-linked polyester resin film with surface scratches disappeared 30: Two-layer cross-linked polyester resin film 31, 31A: Adhesive layer 35: Two-layer cross-linked polyester resin film with broken edges 36: Laminated (two-layer) portion 40: Tweezers 41: Spartel 42: Tape 50: Scratch 60: Ester exchange catalyst solution

Claims (13)

A polyester resin containing a polymer main chain containing multiple ester bonds, a multi-point covalently bonded crosslinked portion containing an ester bond and a free OH group, and a crosslinked polyester resin containing an ester exchange catalyst. The crosslinked polyester resin according to claim 1, which is obtained by mixing a polyester resin raw material containing an ester bond and a carboxylic acid group at a large number of points, a diepoxy crosslinking agent, and the transesterification catalyst, and heating and crosslinking the mixture. The crosslinked polyester resin according to claim 2, wherein the polyester resin raw material has an average molecular weight of 8000 or more, and the polyester resin raw material has 100 or more polyester bonds. The ratio of the carboxylic acid group of the polyester resin raw material is 10 mol% to 50 mol% with respect to the ester group of the polyester resin raw material, and the carboxylic acid group of the polyester resin raw material and the diepoxy cross-linking agent in the cross-linking reaction are present. The crosslinked polyester resin according to claim 2 or 3, wherein the ratio of the epoxy group (carboxylic acid group: epoxy group) is 1: 0.5 to 1: 1.5. The second to fourth claims, wherein the molar ratio of the transesterification catalyst to the free OH group (free OH group: transesterification catalyst epoxy group) in the network structure after cross-linking is 1: 0.1 to 1: 0.4. Crosslinked polyester resin. A method for producing a crosslinked polyester resin obtained by mixing a polyester resin raw material containing an ester bond and a carboxylic acid group at multiple points, a diepoxy crosslinking agent, and a transesterification catalyst, and heating and crosslinking. The crosslinked polyester resin according to any one of claims 1 to 5, wherein the crosslinked polyester resin is in the form of a film. A multilayer crosslinked polyester resin film comprising a portion in which the film-shaped crosslinked polyester resin according to claim 7 is adhered and laminated. A packaging body characterized in that the multilayer crosslinked polyester resin film according to claim 8 is used at least partially. The method for producing a multilayer crosslinked polyester resin film, which presses at least a part of the film-shaped crosslinked polyester resin according to claim 7 at a high temperature. A method for producing a remolded crosslinked polyester resin, which comprises a deformation step in which the crosslinked polyester resin according to claim 7 is deformed with respect to its shape, and then a heat treatment step in which the crosslinked polyester resin is treated by heat. A method for producing a crosslinked polyester resin in which the scratches have been repaired, which comprises a step of scratching the surface of the crosslinked polyester resin according to claim 7 and then a heat treatment step of treating the crosslinked polyester resin with heat. A solution containing the ester exchange catalyst, which is obtained by mixing a polyester resin raw material containing an ester bond and a carboxylic acid group at multiple points with a diepoxy cross-linking agent and heating and cross-linking the cross-linked polyester resin without an ester exchange catalyst. A method for producing a crosslinked polyester resin obtained by immersing in.

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