JP2010180345A - Polyester film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester film which permits color change by solving problems such as environmental load due to inkjet method and cost and by using inexpensive and simple ultraviolet irradiation, therefore, can be used for ultraviolet rays intensity measurement for various applications such as outdoor building material and, further, can be applied for usage as UV photosensitive marker in electronic parts and optical sensor technique. <P>SOLUTION: The polyester film contains 0.05 to 1.00 wt.% of diarylethene type compound. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a transparent polyester film that changes color (hereinafter sometimes referred to as a color change) upon irradiation with ultraviolet rays (hereinafter sometimes abbreviated as UV).

  In recent years, functional polyester films have been used in a variety of fields ranging from solar cells, electronic equipment, and other home decorations such as building materials. In addition, a functional polyester film may be used as a mark for decoration or cutting in the production line. In these applications, low-cost, environmentally friendly and highly functional polyester films are desired.

  As an existing polyester film, a polyester film that has been printed by a mainstream inkjet method is known as a building material application for household goods decoration. The problems with the inkjet method are that a large amount of various polymers and pigments are used, so the burden on the environment is large, the size of maintenance such as contamination, capital investment costs, running costs, and production lines When used as a mark, there are technical difficulties such as a need for a drying process, contamination of the process with ink, and changes in film thickness.

  For example, if a polyester film having UV-sensitive light emitting or phosphorescent performance is used instead of the conventional inkjet method, ink is not used as a mark in the production line described above, and the film thickness is not changed. The coloration can be visually judged at the time of irradiation, and it can be expected as a novel coloring method with high utility value because it remains transparent because there is no strong UV light source where there is no need for coloring except in the process.

  Further examples include not only the possibility of use as a UV photosensitive marker or photosensor technology in electronic parts, but also the possibility of application to beautiful household goods using UV photosensitive coloring technology.

  There are several problems with UV-sensitive organic compound-containing polyesters. For example, a UV-sensitive organic light-emitting compound may be decomposed due to melting of the film or heat (about 300 ° C.) applied during film formation. In addition, the UV light-sensitive organic compound may have low dispersibility with respect to inclusion in various methods in the polyester, and in this case, the expected coloring function may not be exhibited. On the other hand, when a large amount of the UV-sensitive organic light-emitting compound is blended in the polyester with emphasis on the function, problems of film appearance and production costs occur.

JP 2007-146014 A

  The present invention has been made in view of the above circumstances, and its solution is to solve problems such as environmental burden and cost due to the ink jet method, and can be color-changed by inexpensive and simple UV irradiation, and has high heat resistance. The present invention relates to a polyester film containing a diarylethene compound, which is an organic photochromic compound having properties and dispersibility.

  As a result of intensive studies in view of the above circumstances, the present inventor has found that the above problem can be easily solved by a polyester film having a specific configuration, and has completed the present invention.

  That is, the gist of the present invention resides in a polyester film characterized by containing 0.05 to 1.00% by weight of a diarylethene compound.

Hereinafter, the present invention will be described in more detail.
The polyester film of the present invention may have a single layer structure or a multilayer structure, and may have a multilayer of 4 layers or more unless the gist of the present invention is exceeded other than the two-layer or three-layer structure. There is no particular limitation.

  The polyester used in the present invention may be a homopolyester or a copolyester. In the case of a homopolyester, those obtained by polycondensation of an aromatic dicarboxylic acid and an aliphatic glycol are preferred. Examples of the aromatic dicarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid, and examples of the aliphatic glycol include ethylene glycol, diethylene glycol, and 1,4-cyclohexanedimethanol. Typical polyester includes polyethylene terephthalate and the like. On the other hand, the dicarboxylic acid component of the copolyester includes isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, oxycarboxylic acid (for example, p-oxybenzoic acid, etc.), etc. 1 type or 2 types or more are mentioned, As a glycol component, 1 type or 2 types or more, such as ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1, 4- cyclohexane dimethanol, neopentyl glycol, is mentioned.

  In the polyester film of the present invention, it is preferable to blend particles mainly for the purpose of imparting easy slipping and preventing the occurrence of scratches in each step. The kind of the particle to be blended is not particularly limited as long as it is a particle capable of imparting slipperiness. Specific examples thereof include silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, and phosphoric acid. Examples of the particles include magnesium, kaolin, aluminum oxide, and titanium oxide. Further, heat-resistant organic particles as described in JP-B-59-5216, JP-A-59-217755 and the like may be used. Examples of other heat-resistant organic particles include thermosetting urea resins, thermosetting phenol resins, thermosetting epoxy resins, benzoguanamine resins, and the like. Furthermore, precipitated particles obtained by precipitating and finely dispersing a part of a metal compound such as a catalyst during the polyester production process may be used.

  On the other hand, the shape of the particles to be used is not particularly limited, and any of a spherical shape, a block shape, a rod shape, a flat shape, and the like may be used. Moreover, there is no restriction | limiting in particular also about the hardness, specific gravity, a color, etc. These series of particles may be used in combination of two or more as required.

  Moreover, the average particle diameter of the particle | grains to be used is 0.01-3 micrometers normally, Preferably it is the range of 0.1-2 micrometers. If the average particle size is less than 0.01 μm, the slipperiness may not be sufficiently imparted, or the particles may be aggregated to make the dispersibility insufficient, thereby reducing the transparency of the film. On the other hand, if it exceeds 3 μm, the surface roughness of the film becomes too rough, which may cause problems such as poor film appearance.

  Further, the content of particles in the polyester layer is usually in the range of 0.001 to 5% by weight, preferably 0.005 to 3% by weight. When the particle content is less than 0.001% by weight, the slipperiness of the film may be insufficient. On the other hand, when the content exceeds 5% by weight, the transparency of the film may be insufficient. is there.

  The method for adding particles to the polyester layer is not particularly limited, and a conventionally known method can be adopted. For example, it can be added at any stage for producing the polyester constituting each layer, but it is preferably added after completion of esterification or transesterification.

  Also, a method of blending a slurry of particles dispersed in ethylene glycol or water with a vented kneading extruder and a polyester raw material, or a blending of dried particles and a polyester raw material using a kneading extruder. It is done by methods.

  In addition to the above-mentioned particles, conventionally known antioxidants, antistatic agents, thermal stabilizers, lubricants, dyes, pigments, and the like can be added to the polyester film in the present invention as necessary.

  Although the thickness of the polyester film in this invention will not be specifically limited if it can be formed into a film as a film, Usually, 10-350 micrometers, Preferably it is the range of 50-250 micrometers.

  Next, although the manufacture example of the polyester film in this invention is demonstrated concretely, it is not limited to the following manufacture examples at all. That is, a method of using the polyester raw material described above and cooling and solidifying a molten sheet extruded from a die with a cooling roll to obtain an unstretched sheet is preferable. In this case, in order to improve the flatness of the sheet, it is preferable to improve the adhesion between the sheet and the rotary cooling drum, and an electrostatic application adhesion method and / or a liquid application adhesion method is preferably employed. Next, the obtained unstretched sheet is stretched in the biaxial direction. In that case, first, the unstretched sheet is stretched in one direction by a roll or a tenter type stretching machine. The stretching temperature is usually 70 to 120 ° C., preferably 80 to 110 ° C., and the stretching ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times. Next, the film is stretched in the direction perpendicular to the first stretching direction. In that case, the stretching temperature is usually 70 to 170 ° C., and the stretching ratio is usually 3.0 to 7 times, preferably 3.5 to 6 times. is there. Subsequently, heat treatment is performed at a temperature of 180 to 270 ° C. under tension or under relaxation within 30% to obtain a biaxially oriented film. In the above-described stretching, a method in which unidirectional stretching is performed in two or more stages may be employed. In that case, it is preferable to carry out so that the draw ratios in the two directions finally fall within the above ranges.

  For the production of the polyester film of the present invention, a simultaneous biaxial stretching method can also be employed. The simultaneous biaxial stretching method is a method in which the above-mentioned unstretched sheet is usually stretched and oriented in the machine direction and the width direction at a temperature controlled normally at 70 to 120 ° C., preferably 80 to 110 ° C. Is 4 to 50 times, preferably 7 to 35 times, and more preferably 10 to 25 times in terms of area magnification. Subsequently, heat treatment is performed at a temperature of 170 to 250 ° C. under tension or under relaxation within 30% to obtain a stretched oriented film. With respect to the simultaneous biaxial stretching apparatus that employs the above-described stretching method, a conventionally known stretching method such as a screw method, a pantograph method, or a linear driving method can be employed.

  The diarylethene compound used in the present invention may be one type or a combination of two or more types, and the type and mixing are not particularly limited.

  Specific examples of the diarylethene compound include cis-1,2-dicyano-1,2-bis (2,4,5-trimethyl-3-trienyl) ethene and 1,2-bis (2,4-dimethyl-5). -Phenyl-3-trienyl) -3,3,4,4,5,5-hexafluoro-1-cyclopentene, 1,2-bis [2-methylbenzo [b] thiophen-3-yl] -3,3 Examples include 4,4,5,5-hexafluoro-1-cyclopentene.

  The content of the organometallic chelate complex in the film is in the range of 0.05 to 1.00% by weight. When the content is less than 0.05% by weight, the light emission of the film is inferior. On the other hand, when it contains exceeding 1.00 weight%, a malfunction arises with the degraded material in a film.

  As for kneading diarylethene compounds into polyester, it is preferable to use them as a masterbatch in which these compounds are kneaded into polyester resin, but they may be added directly to polyester resin.

  Further, the kneading layer of the diarylethene compound may be either a surface layer or an intermediate layer of the polyester film. What is necessary is just to adjust content of a surface layer or an intermediate | middle layer so that it may become said content as the whole film.

  After the UV irradiation of the polyester film of the present invention, the contrast ratio by luminance measurement is preferably 101% or more, and the ΔE value obtained from the evaluation of L * a * b * color difference by a color difference meter is preferably 5 or more.

  According to the polyester film of the present invention, a polyester film having reversible color change performance with high transparency can be provided, and its industrial value is high.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded. The measurement method and evaluation method used in the present invention are as follows.

(1) Visualization before UV irradiation (of the film) and transmittance evaluation As a reference for transparency, there are visual evaluation of transparency and transmittance measurement, and judgment is made based on the following criteria.
-Regarding visual observations, the case of being almost transparent was indicated as ◯, the case of being transparent but slightly colored in pink, and the case where yellow or red was strongly cloudy as x.
-Regarding transmittance measurement In accordance with JIS K7105, the total light transmittance of the film was measured with an integrating sphere turbidimeter NDH-300A manufactured by Nippon Denshoku Industries Co., Ltd. The transmittance decrease in the range of 0.5 to 1% with respect to the transmittance of a general polyester film is ◎, the transmittance decrease in the range of 1-2% is ○, and the range of 2 to 4% The decrease in transmittance was evaluated as Δ, and the decrease in transmittance exceeding 4% was evaluated as x.

(2) UV irradiation part ΔE visual evaluation Using a color difference meter, the L * a * b * color difference between the uncolored part of the film before UV irradiation and the colored part after UV irradiation was evaluated. The method was performed according to JIS Z 8729, using a Konica Minolta color difference meter: CR-410 (sample diameter: 50 mm) to measure L * a * b * color difference values of the UV irradiated portion and the non-irradiated portion. At this time, the light source was C / D65, the back surface was white, and measurement was performed by a reflection method. The measurement was performed three times, and an average value was adopted. Thereafter, ΔL * (L * value of the irradiated portion−non-irradiated portion L * value), Δa * (a * value of the irradiated portion−non-irradiated portion a * value), Δb * (b * value of the irradiated portion−non-irradiated) (Part b * value) was determined, and the ΔE value was calculated from the following formula and evaluated.
ΔE = {(ΔL *) 2+ (Δa *) 2+ (Δb *) 2} 1/2
A: Exceeding 20.0, intense coloring O: Coloring in the range of 10.0 to 20.0 Δ: Range in the range of 5 to 10.0, lightly colored ×: Less than 5 Yes, almost uncolored

(3) UV irradiation partial visual evaluation Visual strength was evaluated according to the following criteria.
◎: Strong coloring ○: Colored △: Light color × Not colored

Example 1:
A mixed raw material obtained by mixing polyester and cis-1,2-dicyano-1,2-bis (2,4,5-trimethyl-3-trienyl) ethene in a ratio of 99.95: 0.05 is used as an intermediate layer raw material. As above, each of the mixed raw materials of the surface layer polyester and the intermediate layer is supplied to two extruders at a ratio of 1: 9, melted at 290 ° C., respectively, on a cooling roll set at 40 ° C. Coextruded with a layer structure (surface layer / intermediate layer / surface layer) and cooled and solidified to obtain an unstretched sheet. Next, the film was stretched 3.4 times in the machine direction at a film temperature of 85 ° C. using the roll peripheral speed difference, then led to a tenter, stretched 4.0 times at 120 ° C. in the transverse direction, and heat-treated at 225 ° C. Thereafter, the film was relaxed by 2% in the lateral direction to obtain a yellow transparent polyester film having a thickness of 100 μm (surface layer: 5 μm, intermediate layer: 90 μm). The obtained polyester film was a colorless and transparent film. The polyester film is irradiated with UV (Ushio Electric Co., Ltd .: UVC-402 / 1HN: 302 / 1MN: JC01) light (181 mW / cm ² , 10 m / min, d = 100 mm) with a high-pressure mercury lamp to achieve color change performance. As a result of evaluation, the change to the pink coloring state was satisfactory.

Example 2:
A mixed raw material obtained by mixing a ratio of polyester and cis-1,2-dicyano-1,2-bis (2,4,5-trimethyl-3-trienyl) ethene in a ratio of 99.0: 1.0 is an intermediate layer. This is the same method as in Example 1 except that a polyester film is obtained as a starting material. The obtained polyester film was a colorless and transparent film. The polyester film was subjected to UV irradiation in the same manner as in Example 1 and the color change (coloring) performance was evaluated. As a result, the change to the pink colored state was satisfactory.

Comparative Example 1:
A mixed raw material obtained by mixing a ratio of polyester and cis-1,2-dicyano-1,2-bis (2,4,5-trimethyl-3-trienyl) ethene at a ratio of 99.97: 0.03 is an intermediate layer. This is the same method as in Example 1 except that a polyester film is obtained as a starting material. The obtained polyester film was a colorless and transparent film. The polyester film was irradiated with UV in the same manner as in Example 1 and the color change (coloring) performance was evaluated. As a result, no change to the pink colored state could be confirmed.

Comparative Example 2:
A mixed raw material obtained by mixing a ratio of polyester and cis-1,2-dicyano-1,2-bis (2,4,5-trimethyl-3-trienyl) ethene in a ratio of 98.5: 1.5 is an intermediate layer. This is the same method as in Example 1 except that a polyester film is obtained as a starting material. The resulting polyester film was a yellow film that lost transparency. When the polyester film was subjected to UV irradiation in the same manner as in Example 1 and the color change (coloring) performance was evaluated, the change to a pink colored state was significant.

  The polyester film having color change performance by UV of the present invention can be used as a standard for measuring UV intensity in various applications such as outdoor building materials, and can be used as a UV photosensitive marker or photosensor technology in electronic parts. In addition, there is an expectation for application to beautiful daily necessities using UV photosensitive coloring technology.

Claims (1)

A polyester film comprising 0.05 to 1.00% by weight of a diarylethene compound.