WO2007083720A1

WO2007083720A1 - Polyester foam sheet and method for producing same

Info

Publication number: WO2007083720A1
Application number: PCT/JP2007/050730
Authority: WO
Inventors: Katsuhiro Fujimoto; Tomofumi Maekawa
Original assignee: Asahi Kasei Chemicals Corporation
Priority date: 2006-01-19
Filing date: 2007-01-18
Publication date: 2007-07-26
Also published as: CN101374893A; JPWO2007083720A1; KR20080086903A; TW200730350A

Abstract

Disclosed is a polyester foam sheet containing 50-100% by weight of polytrimethylene terephthalate and having an apparent density of 0.05-1.25 g/cm3. The polyester foam sheet contains bubbles having an average bubble size of 0.01-50 μm, and the ratio between the average size (S) of the bubbles in the surface direction and the average size (T) of the bubbles in the thickness direction (S/T) is 0.05-10. Also disclosed is a method for producing such a polyester foam sheet.

Description

Specification

Polyester foam sheet and method for producing the same

Technical field

The present invention relates to a polyester foam sheet mainly composed of polytrimethylene terephthalate, a method for producing the same, and a light reflector made of the polyester foam sheet. More specifically, a polyester foamed sheet mainly composed of polytrimethylene terephthalate, which has excellent light reflectivity, flexibility, heat insulation and light weight by having fine bubbles inside, and a method for producing the same, In addition, the present invention relates to a light reflecting plate made of the foamed sheet.

Background art

[0002] Polyethylene terephthalate (hereinafter abbreviated as “PET”) resin is a thermoplastic polyester resin represented by polybutylene terephthalate (hereinafter abbreviated as “PBT”) resin, which has excellent heat resistance, chemical resistance, Utilizing characteristics such as weather resistance and mechanical properties, it is widely used in the fields of fibers and molded products. In particular, extruded products such as films and sheets have excellent characteristics in terms of chemical resistance, weather resistance, mechanical properties, etc., and there are a variety of food, daily necessities packaging containers, packaging materials, building materials, light reflectors, etc. It is expected as a material for various applications.

[0003] In these applications, in order to improve flexibility, heat insulation, light weight, and to provide an excellent light reflection function, a sheet containing very fine bubbles of several tens of meters or less inside. The film has come to be strongly desired.

[0004] Conventionally, as a foamed polyester sheet containing fine bubbles in the interior, a polyethylene terephthalate (PET) resin and a non-compatible resin are formed into a uniaxial film after thinly dispersing the film. Alternatively, there is known a polyester film in which fine cavities are formed with an incompatible resin as a core by stretching biaxially (see, for example, Patent Document 1).

[0005] In addition, an average bubble diameter of 50 m or less was obtained by blowing a PET sheet roll into a high-pressure vessel after carbon dioxide was infiltrated and then heating to 240 ° C to infiltrate the infiltrated gas. There is also a proposal of a thermoplastic polyester foam having a fine bubble of 200 m or more and a specific gravity of 0.7 or less (see, for example, Patent Document 2).

[0006] As a similar technique, polytrimethylene capable of obtaining fibers having excellent elastic recovery properties One using terephthalate (hereinafter abbreviated as “PTT”) resin has also been proposed (see, for example, Patent Document 3).

[0007] As a technology that can improve the defect when the processability is bad, the bubble is crushed, the force is easy, the crease or scratch is easy, and the like, the molten thermoplasticity can be improved. After carbonic acid gas was injected into the resin and dissolved, the sheet was molded into a sheet shape at the mouthpiece, and at the same time the dissolved carbon dioxide foamed sheet was cooled on a cast drum, and then stretched and heat-treated. There is a proposal for a white film characterized by having a specific bubble and 95% or more of the components constituting the film made of one kind of thermoplastic resin and stretched at least in one axis (for example, And Patent Document 4).

[0008] Further, 30% by weight or more of the trimethylene terephthalate unit is composed of a trimethylene terephthalate-based polymer force having a specific intrinsic viscosity and an amount of terminal carboxylic acid, and the apparent density is 0.001 gZcm ^{3 to} l. There is also a proposal of a foam that is 2 gZcm ³ (see, for example, Patent Document 5).

[0009] On the other hand, a foamed polyester sheet containing fine bubbles inside has high !, light reflectivity, and high diffuse reflectivity, and is used for lighting of liquid crystal display devices such as light boxes and fluorescent lamps. It is considered to be used for instruments. As such a light reflecting plate, a PET sheet mouth was infiltrated with carbon dioxide gas in a high-pressure vessel, heated to 240 ° C, and foamed with the infiltrated gas. There has been proposed a light reflector made of a thermoplastic polyester foam having fine bubbles with a bubble diameter of 50 m or less, a thickness of 200 m or more, and a specific gravity of 0.7 or less (see, for example, Patent Document 2).

[0010] Further, PET has a specific apparent specific gravity and a specific cavity content obtained by stretching PET and a resin containing polymethylpentene which is incompatible with PET. There is also a proposal of an expanded sheet or film (see, for example, Patent Document 6).

Patent Document 1: Japanese Patent No. 3018539

Patent Document 2: Japanese Patent No. 2925745

Patent Document 3: Japanese Patent Laid-Open No. 11-268212

Patent Document 4: Japanese Patent Laid-Open No. 11-300814

Patent Document 5: Japanese Patent Application Laid-Open No. 2002-226619 Patent Document 6: Japanese Unexamined Patent Publication No. 2005-281396

Disclosure of the invention

Problems to be solved by the invention

[0011] However, in the foamed film of Patent Document 1 described above, bubbles are formed by stretching in the film forming process, so that the film undergoes orientation crystallization and has a low elongation. It has the problem of poor sex. In addition, since the foamed film has a structure in which the resin is laminated in the film surface direction and has air bubbles such as gaps, the air bubbles are crushed when bent or when force is applied from the surface direction. It also has drawbacks such as being easy, and having folds and scratches. In addition, it is difficult to obtain the strength of only a thin film that can be stretched, and it is difficult to stand as a molded body.

According to the study by the present inventors, the sheet obtained by the technique of Patent Document 2 is inferior in flexibility and formability. Moreover, even if this technology is applied to polytrimethylene terephthalate (PTT) as it is, the sheet crystallizes and does not foam when infiltrated with gas, so that a sheet having good flexibility and formability can be obtained. Not only can not be obtained, it is not even possible to obtain a sheet with fine foam.

[0013] In the technique of Patent Document 3, a void-forming thermoplastic resin and Z or bubble-forming inorganic fine particles which are incompatible with polytrimethylene terephthalate (PTT) resin are mixed, and the film is stretched. In the process, bubbles are formed at the interface with the resin or with the inorganic fine particles. However, according to the study by the present inventors, although the flexibility is somewhat increased by using PTT resin having a low crystal elastic modulus, the film is oriented and crystallized and it is a bubble like a gap. Therefore, the effect is not sufficient and it is still difficult to obtain a thick film. As described above, even when the technique of Patent Document 3 is used, the problem that occurs when the polyethylene terephthalate (PET) resin is used cannot be solved.

[0014] In the techniques of Patent Documents 4 and 5, a volatile foaming agent of 1% by weight or more, specifically 20% by weight of carbonic acid carbon dioxide or 4% by weight of 11 butane is injected with respect to the resin. Dissolved to obtain a foam. However, according to the study by the present inventors, although the foam can be obtained by these techniques, the bubbles cannot be made fine, and the above-mentioned problem cannot be solved.

[0015] Thus, the conventional technology so far has excellent flexibility, heat insulation, light weight, and light reflectivity. There was a problem that it was not possible to obtain a foam sheet having the above.

On the other hand, when considered as a light reflector, since the technique of Patent Document 2 uses PET, it is inferior in flexibility and difficult to process into a shape corresponding to the light source, or inferior in elastic recovery. Therefore, if you try to process it into a curved surface according to the light source, it will bend and if it has a problem, it will have a problem.

[0016] Further, since the sheet obtained by the technique of Patent Document 6 has a high reflectivity even if it is thin, it can be easily deformed by reducing the thickness. Is flat because it can be formed by stretching, and if the curvature when processing into a curved surface is reduced, it may easily be bent at an acute angle or cause frequent wrinkles! .

[0017] As described above, according to the conventional techniques so far, it is possible to obtain a light reflecting plate that can be easily processed into a shape suitable for various light sources and that can form a wide shape such as a curved surface with a small curvature. There was also a problem that could not be done.

[0018] The present invention solves the above-mentioned problems, and an object of the present invention is to provide a polyester foamed sheet mainly composed of polytrimethylene terephthalate having excellent light reflectivity, flexibility, heat insulation, and light weight, and its It is an object of the present invention to provide a light reflecting plate having excellent light reflectivity made of the foamed sheet and capable of being easily processed into a shape suitable for a light source without any defects.

Means for solving the problem

[0019] As a result of intensive studies to solve the above problems, the inventors of the present invention have a composition of a resin composition mainly composed of polytrimethylene terephthalate (PTT), and have ultrafine bubbles having a specific shape inside. The inventors have found that the above problems can be solved by using a fine foam sheet, and have completed the present invention. That is, the object of the present invention has been achieved by the following polyester foam sheet and production method thereof.

(1) Polyester foam sheet, containing 50 to 100% by weight of polytrimethylene terephthalate, with an apparent density of 0.05-1.25 gZcm ³ and an average cell size of 0.01-5 O / zm. A polyester foam sheet containing certain bubbles, and having a ratio (SZT) of an average size (S) in the plane direction of the bubbles to an average size (T) in the thickness direction of 0.05 to 10.

(2) The polyester according to (1), wherein the polyester foam sheet has a thickness of 1 μm to 10 mm. Steal foam sheet.

(3) The average bubble size of the bubbles is 0.01 to 30 / ζ πι, and the ratio (SZT) of the average size (S) in the surface direction of the bubbles to the average size (Τ) in the thickness direction is The polyester foam sheet according to (1) or (2), which is 0.7-3.

(4) The polyester foamed sheet according to any one of (1) to (3), wherein the polyester foamed sheet has a thermal shrinkage at 150 ° C. of −2 to 5%.

(5) The polyester foam sheet according to any one of (1) to (4), wherein an average light reflectance of the polyester foam sheet with respect to light having a wavelength of 400 to 700 nm is 80% or more.

(6) The polyester foam sheet according to any one of (1) to (5), which is produced by a melt extrusion method.

(7) An exothermic peak derived from crystallization is observed at 0 to 150 ° C in thermal analysis using an input compensation type differential calorimeter (1) to (6) The polyester foam sheet according to any one of (1) to (6) .

(8) The temperature at which the peak time of isothermal crystallization of the polyester foam sheet is 1 to 60 seconds is in the range of 100 ° C to 150 ° C. (1) to (7) Polyester foam sheet.

(9) A light reflecting plate comprising the polyester foam sheet according to any one of (1) to (8).

(10) The light reflector according to (9), wherein the crystallization-derived exothermic peak observed between 0 and 150 ° C. is 0 to 3 jZg in thermal analysis using an input compensation type differential calorimeter.

(11) Mixing a melt containing polytrimethylene terephthalate 50 to: L00% by weight with 0.01 to 3% by weight of a substance in a gaseous state at normal pressure at the melting temperature of the melt. 'After melting and obtaining a melt, the melt is extruded from a base at an extrusion pressure of 5 ~: LOOMPa and molded, and the injected substance is foamed and cooled and solidified. .

(12) The method for producing a polyester foam sheet according to (11), wherein the substance to be injected is in a gaseous state at normal temperature and normal pressure.

(13) After extruding the melt from a slit-shaped die, the melt is cast on a metal roll or belt, and then the melt is placed in water to cool and solidify (11) (12) The manufacturing method of the polyester foam sheet as described in (12).

(14) 50 The polytrimethylene terephthalate: LOO weight ^_0/0 containing榭脂composition forces the amorphous sheet also be constituted, in a gaseous state is material from 0.01 to 3 wt% injected at ambient temperature and pressure Then, a method for producing a polyester foam sheet, in which the amorphous sheet is heated to 60 to 200 ° C. to foam the injected material.

(15) The method for producing a polyester foam sheet according to any one of (11) to (14), wherein the substance to be injected is nitrogen.

The invention's effect

[0020] The polyester foam sheet according to the present invention has excellent light reflectivity, flexibility, heat insulation, and light weight. For this reason, when used in a light reflecting plate, it has excellent light reflectivity and diffuse reflectivity, and has punching and bending workability that can be easily processed into a shape suitable for a light source. It is useful as a light reflector for a light box of a liquid crystal display device or a lighting fixture such as a fluorescent lamp. In addition, the foamed sheet of the present invention is useful for various applications such as food containers, packaging materials, and building materials.

Brief Description of Drawings

FIG. 1 is a schematic diagram showing one embodiment of a light reflector according to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0022] The present invention will be specifically described below.

The polyester foamed sheet of the present invention is a foamed sheet comprising 50 to 100% by weight of polytrimethylene terephthalate (PTT) resin.

[0023] Here, polytrimethylene terephthalate (PTT) is a PTT repeating unit force having terephthalic acid as an acid component and trimethylene glycol (also referred to as 1, propanediol, hereinafter abbreviated as "TMG") as a diol component. The polyester which becomes.

[0024] The polyester foam sheet of the present invention is 50% by weight to 100% by weight. By using / c ^ PTT resin, a sheet having excellent flexibility and formability can be achieved. This is because, first of all, the proper crystallization rate inherent to PTT, and secondly, the chemical stability derived from the molecular structure of PTT, which is a kind of saturated polyester with low chemical reactivity, and thirdly, This is thought to be derived from the flexibility of the crystal that comes from the zigzag molecular framework. [0025] The proportion of the PTT resin is preferably 70% by weight to 100% by weight from the viewpoints of sheet flexibility, ease of manufacture, and heat resistance, and is preferably 80% by weight to 100% by weight. Is more preferably 90% by weight to 100% by weight. The soot may contain other copolymerization components.

[0026] Examples of copolymer components include ethylene glycol, 1,1 propanediol, 1,2 propanediol, 2,2 propanediol 1,2 butanediol, 1,3 butanediol, 1,4 butanediol, and neopentyl. Glycol, 1, 5 pentamethylene glycol, hexamethylene glycol, heptamethylene glycol, otatamethylene glycol, decamethylene glycol, dodecamethylene glycol, 1,2-cyclohexanediol, 1,3 cyclohexane Diol, 1,4-cyclohexanediol, 1,2 cyclohexanedimethanol, 1,3 cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 5-sodium sulfoisophthalic acid, 3,5-dicarboxylic acid Benzenesulfonic acid tetramethylphosphonium salt, isophthalic acid, oxalic acid, Ester-forming monomers such as succinic acid, adipic acid, dodecanoic acid, fumaric acid, maleic acid, 1,4 cyclohexanedicarboxylic acid, polyethylene glycol, polypropylene glycol, polytetramethylene glycol and copolymers thereof Can be mentioned.

[0027] In order to improve the thermal stability, the flexibility of the sheet, the light reflectivity, and the heat resistance during the production of the sheet, it is possible to control the amount of the above-mentioned components that cause random copolymerization to 30 mol% or less. Preferably, it is more preferably 20 mol% or less, and even more preferably 10 mol% or less.

The degree of polymerization of the soot of the present invention is preferably such that the intrinsic viscosity [η] is in the range of 0.5 dlZg to 4 dlZg. When the intrinsic viscosity is 0.5 dlZg or more, it becomes easy to produce the sheet and it is easy to make the bubble size fine, and it is possible to obtain a foam sheet and a molded body having excellent strength and flexibility. It becomes easy. When the intrinsic viscosity [r?] Is 4. OdlZg or less, it becomes easy to form into a sheet. The intrinsic viscosity [7?] Is more preferably in the range of 0.7 dlZg to 3 dlZg, more preferably in the range of 0.9 dlZg to 2.5 dlZg, particularly preferably in the range of 1.0 dlZg to 2 dlZg.

[0029] The PTT of the present invention preferably has a carboxyl end group concentration of Oeq / ton to 80 eq / ton. By doing this, weather resistance, chemical resistance, hydrolysis resistance of the sheet and molded body It becomes easy to improve the property and heat resistance. The carboxyl end group concentration is more preferably from OeqZ ton to 50eqZ ton or less. OeqZ ton to 30eqZ ton or less is more preferred. The lower the Ome qZkg to 20meqZkg, the better.

[0030] For the same reason, a bis (3-hydroxypropyl) ether component, which is a glycol dimer component in which TMG, which is a glycol component of PTT, is bonded via an ether bond (Structural Formula: — OCH CH CH OCH CH CH O—, hereinafter referred to as “BPE”)

2 2 2 2 2 2

It is preferably ˜2% by weight. The content is more preferably 0.1% by weight to 1.5% by weight, and further preferably 0.15% by weight to 1.2% by weight.

[0031] The polyester foam sheet of the present invention may contain various organic substances, inorganic substances, various additives and the like in addition to PTT. Even in such a case, the PTT ratio needs to be within the above-mentioned range. The ratio of PTT is ¹ H with HFIP: CDC1 = 1: 1 as the solvent.

Three

It can be determined by analysis using a nuclear magnetic resonance spectrum (hereinafter abbreviated as “NMR”). At this time, various PTT oligomers such as cyclic dimers and BPE are included in the PTT ratio.

[0032] Examples of organic substances other than PTT include cyclic and linear PTT oligomers, monomers of acid components and glycol components constituting PTT, low-molecular-weight reactants derived from these, resins other than PTT, and various additions Agents. Other than PTT, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate, polypropylene naphthalate, and other thermoplastic polyesters, thermosetting polyester, nylon 6, nylon 66, nylon 11, Polyamides such as Nylon 12, Polyethylene, Polyethylene, Polyethylene, Polyethylene, Polyurethane, Fluorine-based resin, Silicone-based resin, Polyphenylenesulfite, Epoxy resin, Acrylic resin, Cellulose Etc., and their copolymerized resin.

[0033] Examples of inorganic substances other than PTT include glass fiber, carbon fiber, talc, my strength, wollastonite, kaolin clay, calcium carbonate, titanium dioxide, diacid-silica, and other inorganic fillers, inorganic lubricants, and polymerization catalysts. Examples include residues.

[0034] Examples of additives include organic and inorganic dyes and pigments, matting agents, heat stabilizers, flame retardants, antistatic agents, antifoaming agents, color modifiers, antioxidants, ultraviolet absorbers, and crystal nucleating agents. , Brightener, impurities Scavengers, thickeners, surface conditioners and the like.

[0035] As the heat stabilizer, pentavalent or Z and trivalent phosphorus compounds are preferably hindered phenol compounds. The addition amount of the phosphorus compound is preferably 2 ppm to 500 ppm as the weight ratio of the phosphorus element in the powder, more preferably 10 ppm to 200 ppm force S. Specific compounds include trimethyl phosphite, phosphoric acid, phosphorous acid, tris (2,4 di-tert-butyl butylphenol) phosphite (Irgafosl68 manufactured by Chinoku's Specialty Chemicals Co., Ltd.) Etc.) is preferred.

Here, the hindered phenol compound is a phenol derivative having a substituent having a steric hindrance at a position adjacent to a phenol hydroxyl group, and a compound having one or more ester bonds in the molecule. . The amount of the hindered phenol compound added is preferably 0.001 to 1% by weight, more preferably 0.01 to 0.2% by weight, based on the powder.

[0037] Specific compounds include pentaerythritol-tetrakis [3- (3,5 di tert

-Butyl-4-hydroxyphenol) propionate] (Ciba's Specialty ^ IrganoxlOlO, etc., manufactured by Chemicals Co., Ltd.), 1, 1, 3 Tris (2-methyl-4-hydroxy-5-ter t-butylphenol- E) Butane, Octadecyl 3— (3, 5—Di-tert-Butyl 4-Hydroxyphenyl) Propionate (Chinoku “Specialty” ~ Irganox 1076 manufactured by Chemicals, etc.), N, Ν Xamethylenebis (3,5-tert-butyl 4-hydroxymonohydric cinnamamide), ethylenebis (oxyethylene) bis [3- (5-tert-butynole 4-hydroxy-m-tolyl) propionate] (Chinoku 'Specialty I'Chemicals 'Ir ganox245, etc.), N, hexane-1, 6 dirubis [3— (3,5 di-tert-butyl-4-hydroxyphenylpropionamide) (Ciba Specialty 1' Chemical) (Ltd.) of Ir ganoxl098 etc.) and the like are preferred ヽ. Of course, it is also preferable to use these stabilizers in combination.

[0038] Preferably, a low molecular weight volatile impurity scavenger is added to the foam sheet of the present invention. The scavenger is preferably a polymer or oligomer of polyamide or polyesteramide, a low molecular weight compound having an amide group or an amine group, or the like. The addition amount is preferably 0.001% by weight to 1% by weight as a weight ratio with respect to the powder. 0.2% by weight is more preferred.

[0039] Specific compounds include polyamides such as nylon 6.6, nylon 6, nylon 4.6, and the like, polymers such as polyethyleneimine, and N-phenylenobenzamine and 2, 4, 4-trimethyl. Reaction products with tilpentene (such as Irganox 5057 manufactured by Chinoku 'Specialty I' Chemicals Co., Ltd.), N, hexane-1, 6-dirubis [3— (3,5 di-tert-butyl-4-hydroxy (Ferpropionamide) (Chinoku. Specialty ^ ~ Irgan 0x1098 manufactured by Chemicals, etc.), 2, 6-di-tert-butyl-4- (4,6-bis (octylthio)-1, 3, 5 -Triadine-2-ilamino) phenol (such as Irganox 565 manufactured by Chinoku 'Specialty I' Chemicals) is preferred. Of course, it is also preferable to use these in combination.

[0040] These substances may exist as particles or may be present in a form compatible with polymer molecules. However, in the present invention, particles having an average particle diameter of 0.01 μm to 100 μm are most likely to be present. Compared to 0.1% to 30% by weight, it is preferable. The presence of such particles makes it easy to have many fine bubbles. More preferably, the particles have an average particle size of 0.1 μm to 50 μm, more preferably 0.3 m to 20 μm, and 0.5 m to l 0 μm. Especially preferred!

[0041] The content of the particles is preferably as small as possible as the average particle size of the particles is large, but may be as small as possible, but is more preferably about 0.5 wt% to 20 wt%. More preferably, it is 2% to 10% by weight. It is also preferable that the particles have a flat plate-like or needle-like protrusion that is preferable to a true sphere. The particles are preferably made of a material with low compatibility with PTT and low adhesion.

[0042] Specifically, powders such as talc and polytetrafluoroethylene (hereinafter abbreviated as "PTFE"), such as fluorine-based resin, fluorine mica, plate-like alumina, layered silicate, etc. Is mentioned. Of these, fluorine-based cocoa resin can improve the flexibility of the sheet, heat insulation, and light reflectivity because the size of the bubbles can be improved, and from the viewpoint of heat resistance when manufacturing a preferred sheet PTFE is the most preferred U ヽ.

[0043] The thickness of the polyester foam sheet of the present invention is preferably 1 μm to 10 mm. Thickness If the thickness is not less than the above, handling of the sheet becomes easy, and if it is 10 mm or less, calorie thermoforming becomes easy. The thickness of the polyester foam sheet is more preferably 10 μm to 5 mm, and even more preferably 50 m to 3 mm, particularly preferably 100 m to 2 mm.

The polyester foam sheet of the present invention needs to have an apparent density of 0.05 gZcm ^{3 to} l.25 g / cm ³ and an average cell size of 0.01 μm to 50 μm. Only when the density and the cell size are within this range, a foamed sheet having excellent light reflectivity and flexibility, which is less likely to be crushed, and maintains the light weight can be obtained.

Here, the average size of the bubbles is determined by using an image analysis software from a cross-sectional image obtained by observing a cross section of the sheet using a scanning electron microscope (hereinafter abbreviated as “SEM (Scanning Electron Microscope)”). Obtained as the calculated equivalent circle diameter. Polyester apparent density of the foamed sheet is 0. lgZcm ^³ ~lgZcm ³ is preferable instrument 0. 15gZcm ³ ~0 be. 8 g / cm ³ and more preferably instrument 0. 2gZcm ³ ~0 to be. In 7GZcm ³ More preferably it is.

[0046] The average cell size of the polyester foam sheet is preferably from 0.01 μm to 30 μm, more preferably from 0.01 μm to 20 μm than the force S, from 0.01 μm to A force of 10 μm ^ is more preferable. From the viewpoint of imparting excellent light reflectivity and flexibility, the average bubble size is preferably 1Z5 or less of the sheet thickness, more preferably 1Z10 or less, and 1/50 or less. Is more preferably 1Z100 or less.

[0047] Air bubbles in the polyester foam sheet of the present invention need not be flat. As an indicator of non-flatness, the ratio (SZT) of the average size (S) in the surface direction of the bubbles and the average size (T) in the thickness direction can be used. L0 is required, more preferably ί or 0.1 to 10, more preferably ί or 0.5 to 5, more preferably ί or 0.7 to 3, particularly preferably 1 to 2. . When SZT is in the above range, bubbles in the foamed sheet are difficult to be crushed. Furthermore, coupled with the fact that the foamed sheet of the present invention contains polytrimethylene terephthalate as a main component, the foamed sheet is creased or scratched.

[0048] The crystallinity of the polyester foam sheet of the present invention is preferably adjusted according to the intended use and purpose. When used as an original sheet to form a molded body of a desired shape by thermoforming, it is desirable that the material is in an amorphous state, while a container that requires heat resistance, a light reflecting plate, When used as a U, it should be in a crystalline state.

[0049] The crystalline state index is set to 10 ° CZmin after holding the sheet at 0 ° C for 3 minutes with an input-compensated differential calorimeter (hereinafter abbreviated as "DSC (Differential Scanning Calorimetry)"). The magnitude of the exothermic peak observed when the temperature is raised from 0 ° C to 260 ° C at can be used. The fact that an exothermic peak is observed has room for crystallization, that is, it indicates that the degree of crystallinity is low, that it is easy to heat mold, and that the exothermic peak is not observed or is small This indicates that there is no room to do so, that is, the degree of crystallinity is high.

[0050] When the original sheet for heat forming is used, it is preferable that an exothermic peak is observed, and the heat quantity is preferably lOjZg or more, and more preferably 20jZg or more, and heat resistance is required. In this case, it is preferably 5jZg or less, more preferably 3jZg or less, and even more preferably UZg or less, and most preferably not observed. The upper limit of the heat generation peak is usually 90 jZg or less.

[0051] In order to impart heat resistance by heat crystallization after molding, the temperature when the peak time of isothermal crystallization of the polyester foam sheet is 1 second to 60 seconds is 100 ° C to 150 °. It is preferably in the range of C 2. This is an index indicating the crystallization speed of the resin constituting the sheet, and can be achieved when the resin containing the PTT of the present invention has a specific structure. By using such a sheet, it can be heat-molded and easily crystallized in a relatively short time to impart heat resistance.

[0052] Here, the peak time of isothermal crystallization refers to a composition obtained by rapidly cooling and solidifying a polyester foam sheet melted at 280 ° C in liquid nitrogen, and an input compensation type differential. Hold at 0 ° C for 3 minutes using a calorimeter (DSC), then raise the temperature from 0 ° C to X ° C at a set temperature increase rate of 500 ° C Zmin and hold at X ° C The time at which the endotherm derived from the crystallization observed at the time of peaking is shown. The above temperature range is preferably 5 ° C or higher continuously, more preferably 10 ° C, more preferably 20 ° C or higher, and the temperature range from 100 ° C to 150 ° C. It is particularly preferable that the peak time is 1 second to 60 seconds.

[0053] That is, when the polyester foam sheet according to the present invention is subjected to thermal analysis with an input compensation differential calorimeter (DSC), an exothermic peak derived from crystallization is observed between 0 ° C and 150 ° C. The [0054] The polyester foam sheet of the present invention has a heat shrinkage rate of 2% to 5% at 150 ° C in both the machine direction (MD) and the transverse direction (TD). Power is preferred. The thermal contraction rate is an index indicating distortion when the polymer molecules constituting the sheet are fixed, and 0% indicates no distortion. By making the strain in the above range small, it is possible to suppress dimensional changes and sheet deformation when used in a high temperature environment or when the temperature changes. The vertical direction (MD) indicates the take-up direction at the time of manufacturing the sheet, and the horizontal direction (TD) indicates the orthogonal direction. Such a small distortion can be achieved by not excessively stretching and applying tension in the sheet manufacturing process, and the characteristics of the sheet of the present invention that can generate bubbles without stretching using PTT as a raw material. It is.

[0055] The heat shrinkage rate is more preferably 1% to 3%, more preferably 0.5% to 2%, and particularly preferably -0.3% to 1%. preferable. It is preferable that the shrinkage rate is also in directions other than the vertical and horizontal directions. Since the polyester foam sheet of the present invention is not actively stretched, it is easy to achieve such a low heat shrinkage rate, and it is also easy to reduce the shrinkage rate other than the length and width.

[0056] The polyester foam sheet of the present invention preferably has an average light reflectance of 80% or more at a wavelength of 400 nm to 700 nm. By making such a reflectance, it becomes suitable as a light reflector. The average light reflectance is more preferably 85% or more, and more preferably 90% or more. Here, the light reflectance is a relative value when the reflectance of the barium sulfate white plate is 100%. Such light reflectivity can be achieved by using PTT, which absorbs less light in the above-described range, as a raw material and having many fine bubbles without using a pigment that absorbs such light.

[0057] The sheet of the present invention is desired to have good color tone. The color tone is preferably not pigmented or dyed, and it is preferable that L *, which is an indicator of lightness, is 80 or more, more preferably 85 or more, and 90 or more, depending on the state. There is no upper limit for L *, but it is usually 100 or less. In addition, b *, which is an index representing yellowness, is −5 to: LO is preferably 3 to 8, and more preferably 2 to 5, and further preferably 2 to 5.

[0058] Further, the sheet of the present invention preferably has a value obtained by dividing the tensile elastic modulus by the density of 50 to 1500 MPa'cm ³ Zg. Here, the tensile modulus is the average value in the MD and TD directions. Yes. By using a sheet having such a value, it becomes easy to handle while having excellent flexibility. The value obtained by dividing the bow I tensile modulus by density is more preferably 100 to 1200 MPa · cm ³ Zg, 200 to: L 100 MPa'cm ³ / g Force S More preferably, 300 to 1000 MPa ' Especially preferred to be cm 3Zg.

[0059] Next, a method for producing a polyester foam sheet according to the present invention will be described.

[0060] Polyester foamed sheet of the present invention, the melt 50 wt% to 100 wt ^_0/0 also polytrimethylene phthalate (PTT) force, at the melting temperature of the melt, in the gaseous state at normal pressure After a specific amount of a specific substance is injected and mixed and dissolved, it is extruded and molded from a die under specific conditions, and the injected substance is foamed and immediately cooled and solidified. Can be obtained.

[0061] Before describing a specific production method, first, the above-mentioned "special melt extrusion foaming method" will be described.

[0062] Substances that are in the gaseous state at normal pressure can be dissolved to a saturated concentration in the melt of rosin. The saturation concentration decreases as the system pressure decreases. For this reason, the substance dissolved at a high concentration at a high pressure separates from the resin and becomes bubbles when the pressure decreases and the saturation concentration becomes lower than the dissolved concentration. At this time, after passing through the supersaturation state for a short time, first, very small bubble nuclei that are the origin of the bubbles are generated, and then the bubble nuclei grow and bubbles corresponding to the supersaturated concentration are generated.

[0063] In the "special melt extrusion foaming method", in order to generate a large number of fine bubbles, a large number of bubble nuclei that are the origin of the bubbles are generated, and the bubble nuclei do not grow as much as possible. It is important to make it.

[0064] In order to generate a large number of bubble nuclei, it is necessary to set the supersaturation concentration to a certain level or higher. For this purpose, a high-pressure state of a predetermined pressure or higher is required so that the gas substance has a predetermined concentration or higher. It is necessary to release the pressure within a short period of time so that the dissolved substance does not become bubbles, and the saturation concentration is drastically lowered.

[0065] In order to prevent bubble nuclei from growing as much as possible, it is also important not to make the concentration of the substance that becomes a gas too high. This is because bubbles grow rapidly when the supersaturated concentration is too high. In addition, the melt whose pressure has been reduced to normal pressure must be quickly cooled and solidified to suppress bubble growth as much as possible. [0066] Further, according to the study by the present inventors, the use of a melt mainly composed of PTT makes it easier to make bubbles smaller than conventionally known with PET and PBT. The reason for this is not clear, but it seems to be derived from the zigzag molecular structure of PTT, the appropriate polar group concentration, and the relatively low melting temperature.

[0067] Further, in order to make the bubbles into a predetermined range of SZT, that is, non-flat bubbles, which is another object of the present invention, the sheet may not be stretched or compressed. is important. In general, a PET microfoamed sheet used as a light-reflecting sheet generates bubbles with a foreign substance contained therein as a nucleus by stretching a solidified sheet, and thus only flat bubbles can be obtained. Since the “special melt extrusion foaming method” of the present invention does not require such a stretching process, it is possible to obtain air bubbles that are not flat. However, also in the present invention, it is necessary to take care not to stretch the sheet until the air bubbles are generated by the extrusion and the force is taken up.

[0068] The production method of the present invention is specifically described below.

[0069] The PTT composition can be obtained by a known method. For example, the PTT composition is made from dimethyl terephthalate and trimethylene glycol, and other copolymerization components as necessary, with titanium tetrabutoxide as a catalyst at normal pressure, 180 ° C to 260 ° C. It can be obtained by performing a transcondensation reaction at 220 ° C. to 270 ° C. under reduced pressure after the transesterification reaction at a temperature of 5 ° C.

[0070] The additive necessary for producing the polyester foam sheet can be added by a method of adding at the time of polymerization, a method of adding by melt-kneading after polymerization, or a method of combining these, etc. The type can be selected as appropriate depending on the type and amount of the additive and the required performance. When various additives are added by melt-kneading, the PTT composition obtained by polymerization is cooled and solidified, or it is put together with various additives into a uniaxial or biaxial extruder in a molten state. Can be done.

[0071] In the above-described special melt extrusion foaming method, the melt composed of PTT is supplied from the extruder using the extruder, the PTT composition is supplied to the supply unit, and the composition is melted by the rotation of the screw. The fed melt is extruded from a slit-like die through a heated channel.

[0072] As the extruder, a single-screw or twin-screw extruder, a tande in which two or more of these are connected in series Can be used. It is preferable to use an optimum screw according to the properties of the PTT composition to be applied and the properties of the substance gas to be injected. It is desirable to set the extruder to a temperature at which no unmelted material remains and the thermal decomposition of the composition can be suppressed. It is preferable to set the melting point of the PTT composition to + 0 ° C to 30 ° C. The melting point + 0 ° C to 20 ° C is more preferable, and the melting point + 0 ° C to 15 ° C is more preferable.

[0073] Between the extruder and the die, if necessary, a filter is installed to remove foreign matter, etc., a gear pump or the like is provided to improve the quantitative supply, and the dispersibility of the injected substance is improved. A static mixer is installed to keep the temperature constant, and a heat exchange unit is installed to keep the temperature constant. In such a case, it is desirable to select the pressure and temperature appropriately so that the substance injected near the equipment must be large bubbles V. Even when installing these devices, it is desirable to set the temperature so that there is no unmelted material and the thermal decomposition of the composition can be suppressed. The melting point of the PTT composition is set to + 0 ° C to 30 ° C. It is preferable to do.

[0074] In the special melt extrusion foaming method, a substance in a gaseous state is injected into the melt at normal pressure at the melting temperature. Considering the ease of handling, the substance to be injected is preferably in a gaseous state at normal temperature and normal pressure. Specific examples include inert compound blowing agents such as nitrogen, carbon dioxide, helium, argon, water, ethane, propane, butane, ethylene, propylene, petroleum ether, pentanes, hexanes, heptanes, toluene, trichloro. Aliphatic hydrocarbon blowing agents such as methane, tetrachloromethane, trichlorofluoromethane, methanol, 2-propanol, isopropyl ether, methylethyl ketone, methyl chloride, dichloroethane, chloroform, fluoromethane, difluoromethane, trifluoroethane, chlorotrifluoro Examples include fluoromethane, dichlorodifluoromethane, fluorochloroethane, and dichlorotetrafluoroethane.

[0075] Specific examples of fluorocarbons include CFC series such as CFC (R-11, R-12), CFC substitute (R-1 34a), CFC-11, CFC-12, CFC-113, CFC-114, etc. And freon (freon) halogenated hydrocarbon foaming agents. Of these, nitrogen, helium, argon, and water are preferred from the viewpoints of not proceeding with crystallization of the sheet and reducing the bubble size, and nitrogen is particularly preferred.

[0076] The amount of such a substance to be injected is that the bubbles are made finer and the surface state of the sheet If it is made good, it is necessary to make it 0.01 to 3% by weight from the point of view. The injection amount is more preferably 0.02% to 1% by weight, and more preferably 0.05% to 0.5% by weight.

[0077] The injection method may be any time as long as it is between the extruder and the die, but it is preferable to inject with an extruder because the substance can be uniformly injected into the melt.

[0078] The melt is then extruded from the die and formed into a sheet-like shape, and the injected substance becomes bubbles by releasing the pressure. Force that can be selected as appropriate according to the shape of the target sheet. In order to obtain a sheet with a uniform thickness, it is called a straight slit such as a T-die or I-die or a round die. It is desirable to use a circumferential slit. It is desirable that the structure of the base is appropriately designed so that foaming does not occur in the base. For this purpose, the pressure of the melt at the inlet of the die needs to be 5 MPa or more, preferably 10 MPa or more, more preferably 12 MPa, and even more preferably 15 MPa or more. . There is no particular upper limit, but considering the structure of the equipment, it is preferable to set the extrusion pressure to be lOOMPa or less, more preferably 50 MPa or less.

[0079] It is preferable to set the die temperature at the time of extrusion within a range where the melt does not solidify. Specifically, the melting point of the composition is preferably + 0 ° C to 30 ° C, and the melting point + It is preferable to set the melting point as low as possible within the range where the melting point that is more preferable to be 0 ° C to 20 ° C + the preferable melting point of 0 ° C to 15 ° C can be uniformly extruded. .

[0080] In the special melt extrusion foaming method, the melted and molded melted sheet is then cooled and solidified. In the present invention, it is necessary to cool and solidify immediately so as to suppress the enlargement of bubbles. As a result, the bubble diameter of the foamed sheet of the present invention can be reduced. Here, promptly refers to cooling so as to have the above-mentioned thermal characteristics of the sheet. Specifically, the time for cooling the sheet below the force crystallization temperature by extruding from the die is within 60 seconds. It is particularly preferable to set it within 40 seconds, more preferably within 20 seconds. When obtaining an amorphous sheet, it is particularly important to cool and solidify immediately.

[0081] As a method for achieving such cooling and solidification, the melt is brought into contact with a solid such as a cooling roll or a cooling belt controlled to a temperature below the crystallization temperature of the PTT composition, or the sheet is made of water or the like. Examples include a method of bringing into contact with a liquid and a method of combining them. . Of these, the most preferred method is to cast (arrange) the melt extruded from the slit-shaped die onto a roll or belt, and then place it in water and immediately cool and solidify.

[0082] Solids such as cooling rolls and belts are preferably made of metal having good heat conduction. The temperature of the solid or liquid to be contacted is more preferably 0 ° C to 50 ° C, and more preferably 0 ° C to 30 ° C, particularly preferably 0 ° C to 20 ° C. It is preferable to set the time from extrusion from the base to contact with the solid or liquid from 0.05 seconds to 10 seconds. 0.1 second to 5 seconds is more preferable. 0.2 seconds to Especially preferred to be 2 seconds.

[0083] In the present invention, care must be taken not to stretch the sheet until the sheet in which bubbles are generated by extrusion is wound up. For this purpose, the winding speed is preferably 10 times or less of the linear velocity of the melt exiting the die, more preferably 8 times or less, and even more preferably 5 times or less. On the other hand, the lower limit is the speed ratio at which the sheet becomes flat. Specifically, 0.9 times or more is preferred, 0.95 or more is more preferred, and 1.0 times or more is more preferred. By setting such a speed ratio, it becomes easy to set SZT within a predetermined range.

[0084] Polyester foamed sheet of the present invention is the amorphous sheet 50 wt% to 100 wt ^_0/0 is榭脂compositions force polytrimethylene terephthalate tallates, a specific amount of the substance that is in the gaseous state at normal temperature and pressure After the injection, it can be produced by “special solid foaming method” in which the sheet is immediately heated to a specific temperature to foam the injected material. However, in this case, only a crystallized sheet can be obtained.

[0085] Before describing a specific production method, first, the "special solid foaming method" will be described.

[0086] A substance that is in a gaseous state at normal pressure can be dissolved in the amorphous sheet to a concentration corresponding to the gas pressure. The dissolved concentration decreases with decreasing system pressure. In the “special melt foaming method”, when the saturation concentration becomes lower than the dissolved concentration, it separates from the resin and becomes bubbles, but in the solid, it is gradually released from the surface and does not become bubbles. However, if the sheet is heated to a temperature higher than the glass transition point, bubbles are formed in the same manner as the melt.

[0087] In the "special solid foaming method", in order to generate a large number of fine bubbles, a large number of bubble nuclei that are the origin of the bubbles are generated, and the bubble nuclei are not grown as much as possible. It is important to. [0088] In order to generate a large number of bubble nuclei, a large amount of bubbles are injected at a high pressure above a predetermined pressure so that the gas becomes a predetermined concentration or more, and the injected material is released from the surface. As such, it is necessary to quickly bring the sheet to a temperature above the glass transition point.

[0089] In order to prevent bubble nuclei from growing as much as possible, it is also important not to make the concentration of the substance that becomes a gas too high. This is because bubbles grow rapidly when the concentration is too high.

[0090] Since PTT has a higher crystallization rate than PET, it is important to raise the temperature of the sheet rapidly. Since PBT has an extremely fast crystallization rate, it is not possible to obtain an amorphous sheet, and it is not possible to obtain a foamed sheet by the same method.

[0091] In addition, in order to make the bubbles into a predetermined range of SZT, that is, non-flat bubbles, which is another object of the present invention, the sheet may not be stretched or compressed. is important. In the “special solid foaming method” of the present invention, it is possible to obtain non-flat bubbles because no stretching or compression process is required. However, in the present invention, care must be taken not to stretch the sheet after bubbles are generated by heating the sheet.

[0092] The "special solid foaming method" of the present invention will be specifically described below.

[0093] Specific examples of substances in a gaseous state at normal temperature and pressure injected into a sheet by a special solid foaming method include inert compound blowing agents such as nitrogen, helium and argon, ethane, propane, butane, ethylene, Propylene, petroleum ether, pentanes, hexanes, heptanes, toluene, trichloromethane, tetrachloromethane, trichlorofluoromethane, methyl chloride, dichloroethane, fluoromethane, difluoromethane, trifluoroethane, chlorotrifluoromethane, di Examples include chlorodifluoromethane, fluorochloroethane, dichlorotetrafluoroethane and the like. Of these, nitrogen, helium, and argon are preferable from the viewpoint of reducing the bubble size, and nitrogen is particularly preferable.

[0094] The amount of such a substance to be injected needs to be 0.01 wt% to 3 wt% from the viewpoint of miniaturizing the bubbles. The injection amount is more preferably 0.02% to 1% by weight, and more preferably 0.05% to 0.5% by weight.

[0095] As a method of injecting, an amorphous sheet is contained in the gas atmosphere having a pressure of 0.5 MPa or more. This can be achieved by adding 10 minutes or more. The pressure is more preferably lOMPa or more, and further preferably 15 MPa or more. The time is more preferably 30 minutes or more, more preferably 60 minutes or more, and particularly preferably 120 minutes or more. When injecting gas, the temperature of the sheet should be 40 ° C or lower, preferably 20 ° C or lower, more preferably 10 ° C or lower so as not to crystallize.

[0096] The sheet infused with such a gas is immediately heated to 60 ° C to 200 ° C to foam the injected material. Here, promptly means that the injected gas does not fall below the above amount. The heating temperature is more preferably from 100 ° C to 200 ° C, more preferably from 120 ° C to 200 ° C. At this time, in order to foam, it is important to heat rapidly so as to foam before crystallization. Such heating can be achieved by dipping in a heated inert liquid or by contacting with a heated roll.

[0097] Of the polyester foam sheet of the present invention, an amorphous one can be formed into a foam-molded product by molding.

[0098] The foamed molded article is preferably crystallized during molding. By doing so, the heat resistance can be increased. Regarding the degree of crystallization, when a polyester foam sheet is subjected to thermal analysis with an input compensation differential calorimeter (DSC), no exothermic peak derived from crystallization is observed between 0 ° C and 150 ° C. U, who prefers it.

[0099] In addition, the apparent density of the polyester foam sheet 0. 05gZcm ³ ~l. It is preferable 25gZcm a ³ instrument 0. LgZcm ³ and more preferably ~lgZcm a ³ instrument 0. 15gZcm ³ ~0. it is particularly favorable preferable is ³ further preferred instrument 0. 2gZcm ³ ~0. 7gZcm is 8GZcm ^3.

[0100] The shape of the molded body can be appropriately selected depending on the application. For example, box shape, cup shape, corrugated plate shape and the like can be mentioned. Examples of a method for forming such a molded body include press molding, straight molding, drape molding, plug assist molding, vacuum molding, vacuum / pressure forming, and pressure forming, among which vacuum / pressure forming is more preferable.

[0101] When forming, it is preferable to first heat the sheet to a temperature of 30 ° C to 80 ° C by means of heater radiation or a heating plate. By doing so, it becomes easy to soften the sheet without crystallizing, and the moldability and transferability are improved. The temperature is more preferably 40 ° C to 70 ° C, more preferably 45 ° C to 65 ° C, and particularly preferably 50 ° C to 60 ° C. [0102] Next, the sheet is formed by contacting with a mold, and the mold temperature at this time is preferably 60 ° C to 180 ° C. In the present invention, the polyester foam sheet is almost in an amorphous state at the time of shaping in order to ensure moldability, but after shaping, the molded body is crystallized in order to ensure heat resistance. is important. For this purpose, it is preferable to crystallize the molded product by controlling the mold temperature within a certain temperature range. The mold temperature is preferably 65 ° C or higher in order to give sufficient heat resistance to the molded body, and 180 ° C or lower in order to suppress release from the mold or bubble collapse after molding. preferable. The mold temperature is more preferably 80 ° C to 160 ° C, and particularly preferably 100 ° C to 150 ° C. It is also preferable to raise the temperature of the mold after molding or to heat the sheet to the temperature within the above range by heating from the outside.

[0103] In the present invention, the thermoforming can be performed by stacking two or more polyester foam sheets. In this case, it is preferable to provide an air vent hole on the sheet on the side where the pressure increases during molding so that the air between the sheets can be easily removed.

The polyester foam sheet of the present invention is extremely suitable as a light reflecting plate for lighting devices such as light boxes and fluorescent lamps for liquid crystal display devices.

[0104] The functions required of these light reflecting plates include, firstly, having high reflectivity, particularly high diffuse reflectivity. The polyester foam sheet of the present invention contains a large number of fine bubbles such that the average bubble size is 0.0: m to 50 m inside and the density is 0.05 gZcm ³ to 1.25 gZcm ³ . High reflectivity, particularly high diffuse reflectivity, is achieved by the fact that the sheet is not colored, that is, the absorption of light is small.

[0105] Secondly, it can be processed into a shape corresponding to the light source and can retain this shape. It is desirable that machining can be easily carried out (processing can be performed with a small force) and that the machining range is wide, that is, it can be machined into various shapes.

[0106] The light reflector of the present invention has desirable flexibility. In order to achieve only flexibility, the sheet thickness can be reduced.However, if this is done, the rigidity will be lost too much and the force to retain the shape will be weakened, resulting in deformation due to changes in the environment or slight external forces. Sometimes If it is deformed, light cannot be reflected in a desired direction, and in the case of a liquid crystal display panel, light and darkness occurs on the screen. The light reflector of the present invention is 50% to 100% by weight It is composed of polytrimethylene terephthalate, which has a zigzag molecular skeletal structure and crystal flexibility, and contains many fine bubbles as described above. It becomes a structure and is flexible without reducing the thickness. As a result, both flexibility, that is, workability and rigidity can be achieved.

[0107] Further, the light reflecting plate of the present invention is made of polytrimethylene terephthalate having an elastic recoverability of 50% by weight to 100% by weight of a zigzag molecular skeleton structure and having an SZ T of 0. It is 05-10, and the average bubble size is 0.01 / ζ πι-50 / ζ πι, which is not flat and contains many fine bubbles. Therefore, it can be easily processed into a curved surface or the like without bending or wrinkling. Furthermore, there is a high possibility that even if processing has failed to some extent, it can be restored to its original shape and processed again.

[0108] Such characteristics cannot be expected from a light reflector made of a normal sheet or PET fine foam sheet.

[0109] The light source may be a linear light source such as a fluorescent lamp, a large dot light source such as an incandescent lamp, or a small dot light object such as an LED. It is highly preferable that it can be easily formed in various shapes as described above because it is used in combination. If it bends or appears to be bent, it will not be possible to reflect light in the desired direction. In addition, the liquid crystal display panel will have a streak of light and dark due to the low reflectivity of the edges. It can be done.

[0110] The light reflector of the present invention has a wavelength of 400ηπ! The average light reflectance at ˜700 nm is preferably 80% or more, more preferably 85% or more, and more preferably 90% or more.

[0111] The thickness is preferably 100 / zm to 2mm, more preferably 200 / ζ πι to 1.5mm, considering handling, rigidity during installation, and light concealment. 500 / Particularly preferred is ζ πι to 1.2 mm.

[0112] For the light reflecting plate, it is desirable to have heat resistance because the light source generates heat. For this reason, a crystalline plate is preferred. The crystallinity index is whether or not an exothermic peak derived from crystallization is observed between 0 ° C and 150 ° C when thermal analysis is performed with an input-compensated differential calorimeter. The exothermic peak area is preferably 5jZg or less, more preferably 3jZg or less. Preferred UZg and below are even more preferred and of course most preferably not observed at all.

[0113] The shape of the light reflecting plate is selected according to the light source, and examples thereof include a flat plate shape, a corrugated plate shape, and a box shape. Further, a conical shape, a pyramidal shape, and a bowl shape that can cover light source and reflect light in one direction are also preferable shapes.

[0114] For processing into such a shape, heat that can be performed by slitting, cutting, punching with a die or the like, bending, pressing force, thermoforming, etc. Of these, heat resistance is required. In some cases or when self-holding of the shape is required, it is desirable to perform thermoforming. This is because the deformed portion is heat-set by aging and thus has excellent dimensional accuracy.

Example

Hereinafter, embodiments of the present invention will be described in detail based on examples, but the present invention is not limited to these examples. The main measurement values in the present invention were measured by the following methods.

[0116] (1) Polytrimethylene terephthalate (PTT) content, BPE content:

PTT content (wt%) is insoluble by dissolving sheet lOOmg in HFIP: CDC1 = 1: 1

Three

The component was determined by 1 H-NMR measurement using the solution after filtration with MEMBRANE FILTER (1 μm, PTFE). The measuring machine used was FT-NMR DPX-400 (manufactured by Bruker). The insoluble components removed by filtration were used to determine the PTT content by measuring the weight after vacuum drying.

[0117] (2) Intrinsic viscosity [τ?]:

Intrinsic viscosity [] is measured using a Ostwald viscometer at a temperature of 35 ° C, the specific viscosity in o-black phenol, r? Sp and the ratio of concentration C (g / 100 ml) is 7? It was calculated according to the following equation (1).

[0118] [Equation 1]

[7?] = LinU 77 spZ C)

c → o

[0119] (3) Carboxyl end group concentration:

Dissolve lg in PTT composition lg in 25 ml of benzyl alcohol, add 25 ml of black mouth form, and then titrate with 1Z50N hydroxide-potassium benzyl alcohol solution. From the value VA (ml) and the blank value VO when there is no PTT composition, the following formula (2) was used.

[0120] [Equation 2]

Carboxyl end group concentration (eqZ tons) = (VA-VO) X 20

[0121] (4) Apparent density:

The polyester foam sheet was dried at 50 ° C, and the weight when the constant value was reached was divided by the volume. The volume was determined by immersing the sheet in water.

[0122] (5) Exothermic peak derived from crystallization:

Presence / absence of exothermic peak from crystallization and exothermic peak area are determined for sheet or molded product.

Using a Perkin Elmer Pyris 1 (with cooling unit) as an input-compensated differential calorimeter (DSC), hold it at 0 ° C for 3 minutes, and then change it from 0 ° C to 26 ° C at a set temperature increase rate of 10 ° C Zmin.

The temperature was raised to 0 ° C., and thermal analysis was performed for observation.

[6] (6) Peak time of isothermal crystallization:

The peak time of isothermal crystallization was determined by using a composition obtained by quenching and solidifying a melted sheet at 280 ° C in liquid nitrogen as an input compensated differential calorimeter (DSC). Using Elmer Pyris 1 (with cooling unit), hold at 0 ° C for 3 minutes,

Heated to 0 ° C force X ° C at a set temperature increase rate of 500 ° CZmin, held at X ° C, and determined by measuring the time showing the endothermic force S peak derived from crystallization.

[0124] (7) Ratio of average bubble diameter to average size in surface direction (S) and average size in thickness direction (T) SZ

T:

Ratio of average bubble diameter to average size (S) in the surface direction and average size (T) in the thickness direction SZ T is the sheet cross section in both the MD direction (sheet longitudinal direction) and TD direction (sheet width direction). Was obtained using an image analysis software from cross-sectional images observed using a scanning electron microscope (hereinafter abbreviated as “SEM”). Image- Pro made by BRANETRON Co., Ltd. as image analysis software

Plus ver. 4.0 was used. The average bubble diameter was determined by averaging the average values of the major and uniaxial projections of the equivalent ellipse obtained by approximating the bubble cross-section to an ellipse in each of the MD and TD directions. . S and T are the average values of the height and width of the circumscribed rectangle of the bubble (the smallest rectangle that completely surrounds the bubble and has a side parallel to the sheet surface direction). Were averaged for each of the MD and TD directions.

[0125] (8) Heat shrinkage rate:

In accordance with JIS K7133, the thermal shrinkage was determined by measuring the dimensional change when the film was heat-treated at 150 ° C for 30 minutes without applying tension.

[9] (9) Average light reflectance:

Average light reflectance was obtained by measuring the total reflectance of each wavelength from 400 nm to 700 nm using a Shimadzu UV-2200, shifting the incident angle by 8 °, and calculating the simple average value. At this time, the measuring apparatus was adjusted with barium sulfate powder as 100%.

(10) Color tone (L value, b * value):

Measurement was performed using a color computer of Suga Test Instruments Co., Ltd.

[0127] (11) Flexibility 1:

The state when the sheet was bent to 180 ° C was observed. Evaluated as “X” for fractures, “△” for cracks on the surface, and “◯” for those that did not break or crack.

(12) Flexibility 2:

The tensile modulus was obtained by a tensile test according to ASTM D882, and a value obtained by dividing the modulus by density was used as an index of flexibility and ease of processing.

(13) Workability:

The processing state when bending with a curvature of 3 mm was observed. “X” indicates that the material was bent without any desired curvature and the surface was wrinkled, and “O” was evaluated for power that did not bend and wrinkled.

[Example 1]

Intrinsic viscosity [r?] Is 1.3 dl / g, carboxyl end group concentration is lOeq / ton, BPE content is 0.5 wt% PTT98. 8 parts by weight PTFE with an average particle diameter of 5 m, 1 part by weight, 0.1 parts by weight of Irgafosl68 from Chinoku 'Specialty I' Chemicals Co., Ltd. as thermal stabilizer, and Irganoxl098 from Ciba 'Specialty Chemicals Co., Ltd. as trapping agent for low molecular weight volatile impurities. A PTT composition with a melting point of 225 ° C with 1 part by weight added was fed to a 50mm φ single screw extruder set at 235 ° C, dissolved, and then heated to the same temperature as the extruder. Through the road, it was extruded from a T-die with a width of 100 mm and a spacing of 0.5 mm as a die at a linear speed of 5 mZ and formed into a sheet.

At this time, 0.1% by weight of nitrogen with respect to the composition was injected from the middle of the extruder to be mixed and dissolved with the melt. The melt pressure at the entrance of the T-die was 15 MPa. The melt extruded from the T-die was cast on a metal rotating roll 50 mm away, and then introduced into cooling water to be cooled and solidified to obtain a foam sheet. At this time, the rotating roll and cooling water are controlled to be 10 ° C., and the time from the extrusion of the melt to the contact with the rotating roll is 0.6 seconds, which is the crystallization temperature of the composition. The time to cool to below ° C was within 20 seconds.

[0130] The obtained polyester foam sheet had a thickness of 1 mm and a width of 100 mm, and even when it was bent at 180 °, it did not generate cracks. The intrinsic viscosity [r?] Is 1.15 dlZg, the carboxyl end group concentration is 15 eqZ ton, the BPE content is 0.5% by weight, the density is 0.6 g / cm ³ , and the average bubble diameter is 20 / ζ πι. (SZT) was 1.3 and it had fine, non-flat bubbles, excellent light reflectivity of 85%, and thermal shrinkage of 0.2% in both MDZTD directions. Also, the heat of crystallization was 15jZg, and the peak time of isothermal crystallization was considered to have good thermoformability between 1 second and 60 seconds over the entire range of 100 ° C to 150 ° C. .

[0131] The obtained polyester foam sheet was molded by vacuum / pressure forming to obtain a cup-shaped molded product having an inner diameter of 200 mm and a depth of 50 mm. First, the sheet was heated to 55 ° C with heater radiation, and then molded by bringing it into contact with an aluminum mold heated to 120 ° C at a vacuum degree of 720 mmH and a pressure of 0.2 MPa. This was carried out by holding it for 120 seconds for crystallization. The obtained foamed molded article was a lightweight molded article having an apparent density of 0.6 gZcm ³ . The results are shown in Table 1 and Table 2 below.

In the table, “ME” means special melt extrusion foaming method, “S” means special solid foaming method, and “COOH” means carboxyl end group concentration. In addition, the values listed in the item “Heat Shrinkage” mean the values in MD and ZTD, respectively.

[0132] [Examples 2 to 4]

A polyester foam sheet was obtained in the same manner as in Example 1 except that the conditions shown in Tables 1 and 2 below were changed. The results are shown in Table 1 and Table 2 below. In any case, the present invention It was a polyester foam sheet having excellent lightness and flexibility within the range.

[0133] In Example 2, by increasing the discharge pressure and adding a large amount of PTFE particles having a small particle diameter, a polyester foam sheet having finer! /, Bubbles, high and good light reflectance was obtained. .

[0134] Further, in Example 3, the gas injection amount was increased, and in Example 4, a superior polyester foam sheet was obtained in the same manner as in Example 1 above, in which the thickness of the sheet was changed.

[Example 5]

Intrinsic viscosity [r?] Is 0.9 dl / g, carboxyl end group concentration is 20 eq / ton, BPE content is 0.

A polyester foam sheet was obtained in the same manner as in Example 1 except that the thickness was 0.7 mm. At this time, the interval between the T dies was adjusted so that the pressure of the melt at the T die entrance was 20 MPa or more. The results are shown in Table 1 and Table 2 below. The obtained polyester foam sheet was within the scope of the present invention, and had excellent lightness, flexibility and light reflectance.

[Example 6]

A polyester foam sheet was prepared in the same manner as in Example 1 except that a composition containing 3 parts by weight of fluorine mica having an average particle size of 6 μm (Somasif MAE manufactured by Corp Chemical Co., Ltd.) was used instead of PTFE. Obtained. At this time, the interval between the T dies was adjusted so that the pressure of the melt at the T die entrance was 15 MPa or more. The results are shown in Table 1 and Table 2 below. The obtained polyester foam sheet was within the scope of the present invention, and had excellent lightness, flexibility and light reflectance.

[Examples 7 and 8]

Intrinsic viscosity [r?] 1.15dlZg, carboxyl end group concentration 15eqZ ton, BPE content 0.5% by weight PTT94. 8 parts by weight PTFE with average particle diameter 2m 5 parts by weight, heat stabilizer 0.1 parts by weight of Irgafosl68 manufactured by Chinoku 'Specialty 1' Chemicals Co., Ltd. 0.1 parts by weight of Irganoxl098 manufactured by Chiba 'Specialty Chemicals Co., Ltd. as a scavenger for low molecular weight volatile impurities A non-foamed sheet of 0.4 mm thickness made of PTT composition with a molten melting point of 225 ° C was placed in a nitrogen atmosphere of 20 MPa with the temperature kept at 20 ° C or lower in Example 7. Nitrogen was introduced at 0.2% by weight for 120 minutes, and in Example 8, the temperature was kept at 20 ° C or lower and the atmosphere was placed in a 15 MPa argon atmosphere for 100 minutes. After 0.2 wt ^_0/0 injecting Gon, foamed rapidly heated by, take into an oil bath at 180 ° C within 3 minutes after the extraction to give a polyester foam sheet. The results are shown in Table 1 and Table 2 below. All of the obtained polyester foam sheets were within the scope of the present invention, and had excellent lightness, flexibility, and light reflectance.

[0138] [Comparative Examples 1 and 2]

Instead of 95 parts by weight of PTT, in Comparative Example 1, 95 parts by weight of PET with an intrinsic viscosity [r?] Of 0.85 dlZg and a carboxyl end group concentration of 30 eqZ tons and 5 parts by weight of talc with an average particle size of 5 μm, In Comparative Example 2, the above example was used except that 95 parts by weight of PBT having an intrinsic viscosity [7?] Of 1. Odl / g and a carboxyl end group concentration of 50 eqZ ton and 5 parts by weight of talc having an average particle diameter of 5 μm were used. A polyester foam sheet was obtained in the same manner as in 1. In Comparative Example 2, the temperatures of the extruder, T-die, etc. were set 30 ° C. higher than in Example 1. The results are shown in Table 1 and Table 2 below.

[0139] The sheet of Comparative Example 1 had a large bubble diameter and low light reflectance. Further, the sheet of Comparative Example 2 was inferior in flexibility, not only having a large bubble diameter and low light reflectance, but also breaking into two when bent at 180 °.

[0140] [Comparative Example 3]

A foamed sheet was obtained in the same manner as in Example 1 except that the discharge pressure was set to 2 MPa by adjusting the interval between the T dies. The results are shown in Table 1 and Table 2 below. The obtained sheet had a large bubble diameter and low light reflectance.

[0141] [Comparative Example 4]

An attempt was made to obtain a foam sheet in the same manner as in Example 7 except that 0.8 wt% carbon dioxide gas was injected under the condition that carbon dioxide gas of 4 MPa was used instead of nitrogen and the temperature was kept at 20 ° C. or lower. did. However, no foaming was observed when placed in an oil bath at 180 ° C. The results are shown in Table 1 and Table 2 below.

[0142] [Comparative Example 5]

A roll of a non-oriented amorphous sheet of 250 μm thickness made of the same PET used in Comparative Example 1 and a non-woven polyethylene nonwoven fabric is held in acetone vapor at atmospheric pressure for 48 hours, then taken out and pressure vessel It was impregnated with carbon dioxide of 5 MPa for 2 hours at 20 ° C. Then, it was put in a heating furnace set to 200 ° C. and foamed to obtain a foamed sheet. Obtained foam The sheet was a foam sheet having a thickness of 1 mm, an apparent density of 0.4 gZcm3, an average cell diameter of 3 / ζ πι, an SZT of 1.2, and a light reflectivity of 90%. The sheet was evaluated for flexibility and strength in the same manner as the film of the present invention. As a result, it was easy to bend, and when it was bent to a curvature of 3 mm, many sheets were generated. have done.

[Example 9]

Using the sheets of Examples 1 and 2 and Comparative Examples 1 and 3, a 26-inch size knocklight unit for a liquid crystal display panel was prepared. As the light source, 16 cold cathode tubes were used, and the foamed sheets of Example 2 and Comparative Example 3 were used as wave-shaped light reflectors as shown in FIG. 1 by vacuum forming. In FIG. 1, the cold cathode tube was placed 5 mm above the center of the recess on the lower surface of the foam sheet. On the other hand, since the sheet of Comparative Example 2 was difficult to process, it was used as a flat light reflector, and the cold cathode tubes were arranged on the sheet 5 mm at the same intervals as described above. On the above light source, a 1.5 mm thick diffuser plate (Delaglass DS manufactured by Asahi Kasei Chemicals Corporation) was drawn to obtain a backlight unit.

[0144] When the light reflecting plate made of the sheet of Example 2 was used, the luminance was high, and the luminance unevenness derived from the cold cathode tube was strong.

[0145] On the other hand, when the light reflector made of the sheets of Comparative Examples 1 and 2 is used, the luminance is lower than that of Examples 1 and 2, and the streak-like luminance derived from the cold cathode tube is used. Unevenness was visually observed. In particular, in the case of Comparative Example 2, the luminance unevenness was remarkable.

[0146] Further, when the backlight unit using the light reflector of Comparative Example 1 was left on for 10 hours, the temperature locally increased to 80 ° C, but the light reflector was not deformed. Natsuki.

[0147] [Table 1] Manufacturing conditions Additive particles Oil properties Manufacturing method Injection material Injection amount Pressure Type Average amount Intrinsic viscosity COOH PTT Particle size Content wt% MPa μm Weight 4% dl / g eq / ton weight% Example 1 ME Nitrogen 0.1 15 PTFE 5 1 1.15 15 98.8 Example 2 ME Nitrogen 0.1 20 PTFE 2 5 1.20 10 94.8 Example 3 ME Nitrogen 0.2 15 PTFE 2 5 1.20 10 94.8 Example 4 ME Nitrogen 0.2 15 PTFE 2 5 1.10 15 94.8 Example 5 ME Nitrogen 0.1 20 PTFE 5 1 0.85 25 98.8 Example 6 ME Nitrogen 0.1 15 Fluorine mica 6 3 1.05 25 96.8 Example 7 S Nitrogen 0.2 20 PTFE 2 5 1.15 15 94.8 Example 8 S Fanregon 0.1 15 PTFE 2 5 1.15 15 94.8 Comparative Example 1 ME Nitrogen 0.1 2 Talc 5 5 0.85 30 0 Comparative Example 2 ME Nitrogen 0.1 2 Talc 5 5 1.00 50 0 Comparative Example 3 ME Nitrogen 0.1 2 PTFE 5 1 1.15 15 98.8 Comparative Example 4 S Charcoal 0.8 10 PTFE 5 1 1.15 15 98.8 Comparison Example 5 S Carbon dioxide 0.8 5--0.85 30 0

[Table 2]

Although the invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. [0150] This application is based on a Japanese patent application filed on January 19, 2006 (Japanese Patent Application No. 2006-0111194), the contents of which are incorporated herein by reference.

Industrial applicability

[0151] The polyester foam sheet of the present invention has excellent flexibility, heat insulation, light weight, and light reflectivity. For this reason, as an example of utilization of this invention, it is useful for various uses, such as a food container, a packaging material, a building material, and a light reflector. In addition, when a light reflecting plate is used, it has excellent light reflectivity and diffuse reflectivity, and has punching and bending workability that can be easily processed into a shape suitable for a light source. Therefore, it is useful as a light reflecting plate for a light box of a liquid crystal display device or a lighting device such as a fluorescent lamp.

Claims

The scope of the claims

[1] A polyester foam sheet,

Polytrimethylene terephthalate 50-100 weight ^_0/0 containing,

The apparent density is 0.05-1 25gZcm ³

Including bubbles with an average bubble size of 0.01 to 50 / ζ πι, and

A polyester foam sheet in which a ratio (SZT) of an average size (S) in the surface direction of the bubbles to an average size (面) in the thickness direction is 0.05 to 10.

[2] The polyester foam sheet according to claim 1, wherein the thickness of the polyester foam sheet is 1 μm to 10 mm.

[3] The average bubble size of the bubbles is 0.01 to 30 / zm, and the ratio (SZT) of the average size (S) in the surface direction of the bubbles to the average size (T) in the thickness direction is 0. . Claims 7 to 3

The polyester foam sheet according to claim 1 or 2.

[4] The thermal shrinkage rate of the polyester foam sheet at 150 ° C. is −2 to 5%.

The polyester foam sheet according to any one of 1 to 3, wherein

5. The polyester foam sheet according to any one of claims 1 to 4, wherein the polyester foam sheet has an average light reflectance of 80% or more with respect to light having a wavelength of 400 to 700 nm.

[6] The polyester foam sheet according to any one of claims 1 to 5, which is produced by a melt extrusion method.

[7] The polyester foam sheet according to any one of claims 1 to 6, wherein an exothermic peak derived from crystallization is observed at 0 to 150 ° C in thermal analysis using an input compensation type differential calorimeter.

[8] The polyester according to any one of [1] to [7], wherein the temperature at which the peak time of isothermal crystallization of the polyester foam sheet is 1 to 60 seconds is in the range of 100 ° C to 150 ° C. Foam sheet.

[9] A light reflecting plate comprising the polyester foam sheet according to any one of claims 1 to 8.

10. The light reflector according to claim 9, wherein an exothermic peak derived from crystallization observed at 0 to 150 ° C. in a thermal analysis with an input compensation type differential calorimeter is 0 to 3 jZg.

[11] Into a melt containing 50% by weight of polytrimethylene terephthalate, 0.01 to 3% by weight of a substance in a gaseous state at normal pressure at the melting temperature of the melt is mixed. '' After dissolving and obtaining a melt,

A method for producing a polyester foam sheet in which the melt is extruded from a die at an extrusion pressure of 5 to: LOOMPa, and the injected material is foamed and cooled and solidified.

12. The method for producing a polyester foam sheet according to claim 11, wherein the substance to be injected is in a gaseous state at normal temperature and normal pressure.

[13] The melt according to claim 11 or 11, wherein the melt is extruded from a slit-shaped base, the melt is cast on a metal roll or belt, and then the melt is cooled and solidified in water. The method for producing a polyester foam sheet according to claim 12.

50 [14] polytrimethylene terephthalate: L00 Weight ^_0/0 containing榭脂composition forces the amorphous sheet also Ru configured, normal temperature and pressure 0.01 to 3 wt% injecting a substance existing as a gas at Thereafter, the amorphous sheet is heated to 60 to 200 ° C. to foam the injected substance, thereby producing a polyester foam sheet.

15. The method for producing a polyester foam sheet according to any one of claims 11 to 14, wherein the substance to be injected is nitrogen.