KR20080086903A - Polyester foam sheet and manufacturing method thereof - Google Patents

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 mum, 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

Polyester foam sheet and its manufacturing method {POLYESTER FOAM SHEET AND METHOD FOR PRODUCING SAME}

The present invention relates to a polyester foam sheet containing polytrimethylene terephthalate as a main component, a method for producing the same, and a light reflection plate made of the polyester foam sheet. More specifically, a polyester foam sheet mainly composed of polytrimethylene terephthalate having excellent light reflectivity, flexibility, heat insulation, and light weight by having fine bubbles therein, a method of manufacturing the same, and a light reflector comprising the foam sheet It is about.

Thermoplastic polyester resins represented by polyethylene terephthalate (hereinafter abbreviated as "PET") resins or polybutylene terephthalate (hereinafter abbreviated as "PBT") resins have excellent heat resistance, chemical resistance, weather resistance, mechanical properties, etc. Taking advantage of its characteristics, it is widely used in fields such as fibers and molded articles. In particular, extruded articles such as films and sheets have excellent characteristics in terms of chemical resistance, weather resistance, mechanical properties, and the like, and are expected to be used as materials for various applications such as food containers, packaging materials for daily necessities, packaging materials, building materials, and light reflecting plates. .

In these applications, sheets or films containing very fine bubbles of several tens of micrometers or less have been strongly desired in order to improve flexibility, heat insulation, light weight, or impart excellent light reflection function.

Conventionally, a foamed polyester sheet containing fine bubbles therein is produced by finely dispersing a polyethylene terephthalate (PET) resin and an incompatible resin therein and stretching the film in one or two axes to make the incompatible resin a nucleus. The polyester film which formed the fine cavity is known (for example, refer patent document 1).

In addition, after the roll of PET sheet penetrated carbon dioxide gas in a high-pressure container, it was heated to 240 ° C. and had fine bubbles having an average bubble diameter of 50 μm or less, and having a thickness of 200 μm or more and specific gravity. There is also a proposal of a thermoplastic polyester foam of 0.7 or less (see Patent Document 2, for example).

As a similar technique, it is also proposed to use a polytrimethylene terephthalate (hereinafter abbreviated as "PTT") resin which can obtain the fiber excellent in elastic recovery (for example, refer patent document 3).

As a technique that can improve the problem of poor workability or defects such as bubbles being easily collapsed or creases or scratches, carbon dioxide is injected into a molten thermoplastic resin and dissolved, The sheet formed by foaming the molten carbon dioxide gas was cooled on a cast drum, then stretched and heat treated, and at least 95% of the components constituting the film having specific bubbles were formed into one kind of thermoplastic resin. There exists a proposal of the white film which consists of and is extended | stretched at least uniaxially (for example, refer patent document 4).

There is also a proposal of a foam having an apparent density of 0.001 g / cm 3 to 1.2 g / cm 3 composed of trimethylene terephthalate-based polymer having at least 30% by weight of trimethylene terephthalate unit and specific intrinsic viscosity and terminal carboxylic acid amount. (For example, refer patent document 5).

On the other hand, the expanded polyester sheet containing fine bubbles therein is considered to be used for lighting devices such as light boxes and fluorescent lamps of liquid crystal displays by utilizing high light reflectivity and high diffuse reflectivity. The light reflecting plate has fine bubbles having an average bubble diameter of 50 μm or less obtained by infiltrating a roll of PET sheet in a high pressure vessel, and then foaming the gas which has been heated to 240 ° C. and has a thickness of 200 μm or more. There is a proposal of a light reflection plate made of a thermoplastic polyester foam having a specific gravity of 0.7 or less (see Patent Document 2, for example).

There is also a proposal of a foam sheet or film having a specific apparent specific gravity and a specific void content obtained by stretching a resin containing polymethylpentene which is incompatible with PET and PET used as a light reflection plate (see Patent Document 6, for example).

Patent Document 1: Japanese Patent No. 3018539

Patent Document 2: Japanese Patent No. 2925745

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

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

Patent Document 5: Japanese Patent Application Laid-Open No. 2002-226619

Patent Document 6: Japanese Patent Application Laid-Open No. 2005-281396

However, in the foamed film of Patent Document 1 described above, since bubbles are formed by stretching in the film forming step, orientation crystallization proceeds in the film, which has a problem of low elongation and poor workability. In addition, since the foamed film has a structure in which resin is laminated in the film plane direction and has the same bubble as the gap, bubbles are likely to be crushed by bending or applying force from the plane direction, or creases and scratches are likely to occur. It also has its drawbacks. Moreover, since only a stretchable thin film is obtained, it is difficult to freely stand as a molded body.

According to examination by the present inventors, the sheet | seat obtained by the technique of patent document 2 will deteriorate flexibility and moldability. In addition, even if the above technique is applied to polytrimethylene terephthalate (PTT) as it is, the sheet is not foamed due to crystallization when gas is infiltrated, so that the sheet having good flexibility and moldability cannot be obtained, and also having fine foaming It is not even possible to get a sheet.

In the technique of Patent Literature 3, an incompatible void-forming thermoplastic resin and / or bubble-forming inorganic fine particles are mixed with respect to polytrimethylene terephthalate (PTT) resin, and the resin interface or the interface with the inorganic fine particles in the stretching process of the film. Bubbles are formed in the. However, according to a study by the present inventors, the flexibility is somewhat increased by using a PTT resin having a low crystal elastic modulus, but the effect is not sufficient because the film does not change to an orientation crystallization or a bubble such as a gap. It is difficult to get a thick film. Thus, even if the technique of patent document 3 is used, the problem which arises when the said polyethylene terephthalate (PET) resin is used cannot be solved.

In the techniques of Patent Documents 4 and 5, a foam is obtained by injecting and dissolving 1% by weight or more of a volatile blowing agent, specifically 20% by weight of carbon dioxide or 4% by weight of n-butane. However, according to a review by the present inventors, foams are obtained in these techniques, but the bubbles cannot be miniaturized, and thus the above problems cannot be solved.

As described above, there has been a problem that a foam sheet having excellent flexibility, heat insulation, light weight and light reflectivity cannot be obtained in the prior art.

On the other hand, when considering it as a light reflecting plate, since the technique of patent document 2 uses PET, it is difficult to process it into the shape according to a light source because it has deteriorated flexibility, or it is processed into the curved surface according to a light source because elastic recovery property is deteriorated. There is a problem of bending or wrinkles.

In addition, the sheet obtained by the technique of Patent Document 6 has a high reflectance even if the thickness is thin, so that the thickness can be made to be easily deformed by making the thickness thin, but because the cavities are formed by stretching, they are processed flat and curved. If the curvature is reduced, it is easily bent at an acute angle or wrinkles are often caused.

As described above, there has been a problem that a conventional light reflection 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 cannot be obtained.

The present invention is to solve the above problems, the object is a polyester foam sheet containing a polytrimethylene terephthalate having excellent light reflectivity, flexibility, heat insulation, light weight as a main component and a manufacturing method thereof, and excellent It is an object of the present invention to provide a light reflecting plate having light reflectivity and capable of easily processing without wrinkles in a shape suitable for a light source.

MEANS TO SOLVE THE PROBLEM As a result of earnestly researching in order to solve the said subject, the subject made of the resin composition which consists of polytrimethylene terephthalate (PTT) as a main component, and makes the said subject into an ultra-fine foam sheet which has a fine bubble of a specific shape inside. The inventors have found something that can be solved and have completed the present invention. That is, the objective of this invention was achieved by the following polyester foam seat | seet and its manufacturing method.

(1) A polyester foam sheet, which contains 50 to 100% by weight of polytrimethylene terephthalate, has an apparent density of 0.05 to 1.25 g / cm 3, and an average bubble size of 0.01 to 50 µm, The polyester foam sheet whose ratio (S / T) of the average size (S) of the bubble direction to the average size (T) of the thickness direction is 0.05-10.

(2) The polyester foam sheet as described in (1) whose thickness of the said polyester foam sheet is 1 micrometer-10 mm.

(3) The average bubble size of the said bubble is 0.01-30 micrometers, and the ratio (S / T) of the average size S of the plane direction of the said bubble, and the average size T of the thickness direction is 0.7-3 ( The polyester foam sheet as described in 1) or (2).

(4) The polyester foam sheet in any one of (1)-(3) whose thermal contraction rate in 150 degreeC of the said polyester foam sheet is -2-5%.

(5) The polyester foam sheet in any one of (1)-(4) whose average light reflectance of the said polyester foam sheet with respect to the light which has a wavelength of 400-700 nm is 80% or more.

(6) The polyester foam sheet in any one of (1)-(5) manufactured by the melt extrusion method.

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

(8) The polyester foam sheet in any one of (1)-(7) which exists in the range of 100 degreeC-150 degreeC in the temperature which the peak time of isothermal crystallization of the said polyester foam sheet being 1 to 60 second.

The light reflection board comprised from the said polyester foam sheet in any one of (9) (1)-(8).

(10) The light reflection plate of (9), wherein the exothermic peak derived from crystallization observed between 0 and 150 ° C in thermal analysis by an input compensated differential calorimeter is 0 to 3 J / g.

(11) to a melt containing 50 to 100% by weight of polytrimethylene terephthalate, in which 0.01 to 3% by weight of a gaseous substance at normal pressure is injected at a melting temperature of the melt to obtain a mixed and dissolved melt. A method for producing a polyester foam sheet which is molded by extruding the melt from the mold at an extrusion pressure of 5 to 100 MPa, and foaming and cooling the injected material.

(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) The polyester according to (11) or (12), wherein the melt is extruded from a slit-shaped mold, and then the melt is cast on a metal roll or belt, and then the melt is poured into water for cooling and solidification. Method for producing foam sheet.

(14) After injecting 0.01 to 3% by weight of a gaseous substance at normal temperature and pressure into an amorphous sheet composed of a resin composition containing 50 to 100% by weight of polytrimethylene terephthalate, the amorphous sheet is brought to 60 to 200 ° C. A method for producing a polyester foam sheet which foams the injected substance by heating.

(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.

(Effects of the Invention)

Polyester foam sheet according to the present invention has excellent light reflectivity, flexibility, heat insulation, light weight. For this reason, when used in a light reflecting plate, it has excellent light reflecting properties and diffuse reflecting properties, and has a punching processing and bending workability that can be easily processed without wrinkles in a shape suitable for a light source, It is useful as a light reflection board of lighting fixtures, such as a fluorescent lamp. In addition, the foam sheet of the present invention is useful in various applications such as food containers, packaging materials, building materials.

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

This invention is demonstrated concretely below.

The polyester foam sheet of the present invention is a foam sheet 50-50% by weight of the polytrimethylene terephthalate (PTT) resin.

Here, polytrimethylene terephthalate (PTT) is a poly consisting of a PTT repeating unit containing terephthalic acid as an acid component and trimethylene glycol (also referred to as 1,3-propanediol, hereinafter abbreviated as "TMG") as a diol component. Ester.

As for the polyester foam sheet of this invention, since 50 weight%-100 weight% consist of PTT resin, the sheet which has the outstanding flexibility and moldability can be achieved. This is because the chemical stability comes from the molecular structure of PTT, which is a kind of moderately intrinsic crystallization rate inherent to PTT in the first place, or the saturated polyester having low chemical reactivity in the second place, and the crystal skeleton comes from the molecular skeleton of Zigzag in third place. It is thought to originate in flexibility.

It is preferable that the ratio of PTT resin is 70 weight%-100 weight% from a viewpoint of the softness of a sheet | seat, the ease of manufacture, and heat resistance, It is more preferable that it is 80 weight%-100 weight%, It is 90 weight%-100 weight% More preferred. The said PTT may contain another copolymerization component.

As the copolymerization component, for example, ethylene glycol, 1,1-propanediol, 1,2-propanediol, 2,2-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, neopentyl Glycol, 1,5-pentamethylene glycol, hexamethylene glycol, heptamethylene glycol, octamethylene glycol, decamethylene glycol, dodecamethylene glycol, 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4 -Cyclohexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 5-sodium sulfoisophthalic acid, 3,5-dicarboxylic acid benzene sulfonic acid Ester-forming monomers such as tetramethyl phosphonium salt, isophthalic acid, oxalic acid, succinic acid, adipic acid, dodecaneic acid, fumaric acid, maleic acid, 1,4-cyclohexanedicarboxylic acid, polyethylene glycol, polypropylene glycol, Polytetramethylene glycol, copolymers thereof, and the like.

In order to increase the thermal stability at the time of producing the sheet, the flexibility of the sheet, the light reflectivity, and the heat resistance, the component is preferably 30 mol% or less, more preferably 20 mol% or less, so that the above-mentioned random copolymerization is performed. More preferably, it is 10 mol% or less.

It is preferable that the polymerization degree of PTT of this invention is a range whose intrinsic viscosity [(eta)] is 0.5 dl / g-4 dl / g. When the intrinsic viscosity is 0.5 dl / g or more, it becomes easy to manufacture a sheet, and it is easy to make the bubble size fine, and it becomes easy to set it as the foam sheet and molded object which have the outstanding strength and flexibility. When intrinsic viscosity [eta] is 4.0 dl / g or less, it becomes easy to shape | mold into a sheet. The intrinsic viscosity [η] is more preferably in the range of 0.7dl / g to 3dl / g, still more preferably in the range of 0.9dl / g to 2.5dl / g, particularly preferably in the range of 1.0dl / g to 2dl / g. Do.

It is preferable that the PTT of this invention is carboxyl terminal group density | concentration of 0eq / ton-80eq / ton. By doing so, it is easy to increase the weather resistance, chemical resistance, hydrolysis resistance and heat resistance of the sheet and the molded body. As for the carboxyl terminal group concentration, 0eq / ton-50eq / ton or less are more preferable, 0eq / ton-30eq / ton or less are more preferable, 0meq / kg-20meq / kg are especially preferable, and it is so low that it is low.

For the same reason, the bis (3-hydroxypropyl) ether component, which is a glycol dimer component in which TMG, a glycol component of PTT, is bound through an ether bond (structure: -OCH ₂ CH ₂ CH ₂ OCH ₂ CH ₂ CH ₂ O- Hereinafter, it is preferable that the content rate of "abbreviated as" BPE "is 0 to 2 weight%. It is more preferable that it is 0.1 weight%-1.5 weight%, and it is still more preferable that it is 0.15 weight%-1.2 weight%.

The polyester foam sheet of the present invention may contain various organic materials, inorganic materials, various additives and the like in addition to PTT. Even in this case, the ratio of PTT needs to be in the above range. Further, the ratio of the PTT is a solvent HFIP: can be obtained by the analysis using a nuclear magnetic resonance spectrum of ¹ H using 1 (hereinafter abbreviated as "NMR"): CDCl ₃ = 1. At this time, various PTT oligomers and BPE, including a cyclic dimer, are included in the ratio of PTT and calculated.

Organic materials other than PTT include cyclic or linear PTT oligomers, monomers of acid and glycol components constituting PTT, low molecular weight reactants derived from them, resins other than PTT, and various additives. Resins other than PTT include thermoplastic polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate, and polypropylene naphthalate, thermosetting polyester, nylon 6, nylon 66, nylon 11, nylon Thermoplastic polyamides such as 12, polyolefins such as polyethylene and polypropylene, polycarbonates, polyurethanes, fluorine resins, silicone resins, polyphenylene sulfates, epoxy resins, acrylic resins, celluloses, and the like, and copolymerized resins thereof. do.

Inorganic materials other than PTT include inorganic fillers such as glass fibers, carbon fibers, talc, mica, walllastite, kaolin clay, calcium carbonate, titanium dioxide and silica, inorganic lubricants, polymerization catalyst residues and the like.

Additives include organic or inorganic dyes, pigments, gloss removers, heat stabilizers, flame retardants, antistatic agents, antifoaming agents, colorants, antioxidants, UV absorbers, crystal nucleating agents, brighteners, impurity trapping agents, thickeners, and surface conditioners. Listed.

As a heat stabilizer, a pentavalent and / or trivalent phosphorus compound and a hindered phenol type compound are preferable. It is preferable that it is 2 ppm-500 ppm, and, as for the addition amount of a phosphorus compound, as a weight ratio of the phosphorus element in powder, 10 ppm-200 ppm are more preferable. Specific examples of the compound include trimethyl phosphite, phosphoric acid, phosphorous acid, and tris (2,4-di-tert-butylphenyl) phosphite (Irgafos 168 from Ciba Specialty Chemicals).

Here, a hindered phenol type compound is a phenol type derivative which has a substituent which has steric hindrance in the adjacent position of a phenol type hydroxyl group, and is a compound which has one or more ester bond in a molecule | numerator. As addition amount of a hindered phenol type compound, it is preferable that it is 0.001 weight%-1 weight% as a weight ratio with respect to powder, and 0.01 weight%-0.2 weight% are more preferable.

Specific compounds include pentaerythritol-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (such as Irganox 1010 from Ciba Specialty Chemicals), 1,1,3- Tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate from Ciba Specialty Chemicals Irganox 1076 and the like), N, N'-hexamethylenebis (3,5-tert-butyl-4-hydroxy-hydrocinnaamide), ethylenebis (oxyethylene) bis [3- (5-tert-butyl- 4-hydroxy-m-tolyl) propionate] (such as Irganox 245 from Ciba Specialty Chemicals), N, N'-hexane-1,6-diylbis [3- (3,5-di-tert-butyl 4-hydroxyphenylpropionamide) (Irganox 1098 from Ciba Specialty Chemicals, etc.), etc. are preferable. Of course, using these stabilizers together is one of the preferable methods.

It is preferable that the low molecular weight volatile impurity trapping agent is added to the foam seat | seet of this invention. As the trapping agent, polymers and oligomers of polyamides and polyesteramides, low molecular weight compounds having amide groups and amine groups, and the like are preferable. As addition amount, it is preferable that it is 0.001 weight%-1 weight% as a weight ratio with respect to powder, and 0.01 weight%-0.2 weight% are more preferable.

Specific compounds include polyamides such as nylon 6.6, nylon 6 and nylon 4.6, polymers such as polyethyleneimine, and reaction products of N-phenylbenzeneamine and 2,4,4-trimethylpentene (Irganox 5057 from Ciba Specialty Chemicals, etc.). ), N, N'-hexane-1,6-diyl bis [3- (3,5-di-tert-butyl-4-hydroxyphenylpropionamide) (such as Irganox 1098 from Ciba Specialty Chemicals), 2, 6-di-tert-butyl-4- (4,6-bis (octylthio) -1,3,5-triazin-2-ylamino) phenol (such as Irganox 565 from Ciba Specialty Chemicals) and the like are preferred. . Of course, using these together is one of the preferable methods.

These substances may exist as particles or may be present in a compatible state with polymer molecules. However, in the present invention, particles having an average particle diameter of 0.01 µm to 100 µm are preferably contained in an amount of 0.1 wt% to 30 wt% with respect to PTT. The presence of such particles makes it easy to have many fine bubbles. It is more preferable that average particle diameters are 0.1 micrometer-50 micrometers, It is still more preferable that it is 0.3 micrometer-20 micrometers, It is especially preferable that they are 0.5 micrometer-10 micrometers.

It is preferable to increase content of particle | grains, if the average particle diameter of particle | grains is large, and it may be small, so that it is small, It is more preferable that it is about 0.5 weight%-20 weight%, It is more preferable that it is 1 weight%-15 weight%, 2 It is especially preferable that they are 10 weight%. The particles preferably have a plate or needle shape that is flatter than the spherical particles, and preferably have projections. In addition, the particles are preferably made of a material having low compatibility with PTT and low adhesion.

Specific examples thereof include fluorine-based resins represented by talc, polytetrafluoroethylene (hereinafter abbreviated as "PTFE"), fluorine mica, plate alumina, layered silicate, and the like. Among them, fluorine-based resins and fluorine mica can make the size of the bubble thin, and thus the flexibility, heat insulation, and light reflectivity of the sheet are improved, and PTFE is most preferred from the viewpoint of heat resistance at the time of sheet production.

It is preferable that the thickness of the polyester foam sheet of this invention is 1 micrometer-10 mm. By controlling the thickness to 1 µm or more, the handleability of the sheet becomes easy, and by setting it to 10 mm or less, heating molding becomes easy. It is preferable that the thickness of a polyester foam sheet is 10 micrometers-5 mm, It is more preferable that it is 50 micrometers-3 mm, It is especially preferable that it is 100 micrometers-2 mm.

The polyester foam sheet of this invention needs to have an apparent density of 0.05 g / cm <3> -1.25g / cm <3>, and an average bubble size of 0.01 micrometer-50 micrometers. By setting it as the density and bubble size of this range, the foam sheet which has the outstanding light reflection property and flexibility, is hard to generate | occur | produce a bubble, and maintains light weight is obtained.

Here, the average size of the bubbles is obtained by calculating the sheet cross section as a circle equivalent diameter calculated using image analysis software from a cross-sectional image observed using a scanning electron microscope (hereinafter abbreviated as "SEM"). The apparent density of the polyester foam sheet is preferably 0.1 g / cm 3 to 1 g / cm 3, more preferably 0.15 g / cm 3 to 0.8 g / cm 3, further preferably 0.2 g / cm 3 to 0.7 g / cm 3. .

It is preferable that the average bubble size of a polyester foam sheet is 0.01 micrometer-30 micrometers, It is more preferable that it is 0.01 micrometer-20 micrometers, It is more preferable that it is 0.01 micrometer-10 micrometers. From the viewpoint of providing excellent light reflectivity and flexibility, the average bubble size is preferably 1/5 or less of the sheet thickness, more preferably 1/10 or less, still more preferably 1/50 or less, particularly 1/100 or less desirable.

The bubble in the polyester foam sheet of this invention does not need to be flat. As an index of non-flat, the ratio (S / T) of the average size (S) in the plane direction of the bubble to the average size (T) in the thickness direction can be used, and the (S / T) needs to be 0.05 to 10. It is present, More preferably, it is 0.1-10, More preferably, it is 0.5-5, More preferably, it is 0.7-3, Especially preferably, it is 1-2. When S / T is in the above range, the foam of the foam sheet is less likely to be crushed, and the foam sheet of the present invention contains polytrimethylene terephthalate as a main component, and it becomes difficult to cause folds or scratches on the foam sheet.

It is preferable to adjust the crystallinity of the polyester foam sheet of this invention according to the use and the objective to be used. It is preferable to be in an amorphous state when it is used as a raw sheet for heat molding to form a desired shaped body, and when it is used as a container or a light reflecting plate which requires heat resistance, it is preferable that it is in a crystalline state.

The index of the crystal state is maintained at 0 ° C for 3 minutes in an input compensated differential calorimeter (hereinafter abbreviated as "DSC" (Differential Scanning Calorimetry)), and then at 0 ° C to 260 ° C at a set temperature rise rate of 10 ° C / min. It is possible to use the size of the exothermic peak observed when the temperature is raised to. The fact that the exothermic peak is observed indicates that there is room for crystallization, that is, the degree of crystallinity is low, so that it is easy to be heat-molded, and the fact that no exothermic peak is observed or small means that there is no room for crystallization, that is, high crystallinity.

It is preferable that exothermic peak is observed when it is set as the one sheet | seat for heat shaping | molding, It is preferable that calorie | heat amount is 10 J / g or more, It is more preferable that it is 20 J / g or more, It is preferable that it is 5 J / g or less when heat resistance is calculated | required. It is more preferable that it is 3 J / g or less, It is more preferable that it is 1 J / g or less, It is most preferable that it is not observed. The upper limit of the exothermic peak is usually 90 J / g or less.

In order to heat-crystallize after molding and impart heat resistance, it is preferable that the temperature when the peak time of isothermal crystallization of the polyester foam sheet is 1 second to 60 seconds is present in a range of 100 ° C to 150 ° C. This is an index showing the crystallization rate of the resin constituting the sheet, and can be achieved by the resin containing the PTT of the present invention having a specific structure. By setting it as such a sheet | seat, it can heat-molding and it can crystallize easily in a comparatively short time, and can provide heat resistance.

Here, the peak time of isothermal crystallization means that the composition obtained by quenching and solidifying the melted polyester foam sheet at 280 ° C. in liquid nitrogen is kept at 0 ° C. for 3 minutes using an input compensation differential calorimeter (DSC). , The temperature at which the temperature increases from 0 ° C to X ° C at a set temperature increase rate of 500 ° C / min and is maintained at X ° C indicates the time when the endothermic resulting from crystallization observed. It is preferable that the said temperature range is continuously 5 degreeC or more, It is more preferable that it is 10 degreeC, It is further more preferable that it is 20 degreeC or more, It is especially preferable that peak time is 1 second-60 second over the temperature range of 100 degreeC-150 degreeC. Do.

That is, the exothermic peak derived from crystallization is observed between 0 degreeC-150 degreeC, when thermally analyzing the polyester foam sheet which concerns on this invention with an input compensation type differential calorimeter (DSC).

It is preferable from the viewpoint of heat resistance and post-processability that the polyester foam seat | seet of this invention is -2%-5% in heat shrinkage in 150 degreeC also in both a longitudinal direction (MD) and a transverse direction (TD). The thermal shrinkage rate is an index indicating unfixed distortion of the polymer molecules constituting the sheet, and 0% indicates no distortion. By setting the distortion of the above-described range small, it is possible to suppress dimensional change and sheet deformation when used in a high temperature environment or when the temperature is changed. The longitudinal direction MD shows the pulling direction at the time of sheet manufacture, and the lateral direction TD shows the orthogonal direction. The smallness of such distortion can be achieved by not excessively stretching or imparting tension in the sheet manufacturing process, and is a feature of the sheet of the present invention that can generate bubbles without stretching using PTT as a raw material.

As for heat shrinkage rate, it is more preferable that it is -1%-3%, It is still more preferable that it is -0.5%-2%, It is especially preferable that it is -0.3%-1%. It is preferable that directions other than paper and a horizontal side also have such a shrinkage rate. Since the polyester foam sheet of this invention does not extend | stretch actively, it is easy to set it as such a low thermal contraction rate, and it is also easy to reduce shrinkage rate other than vertical and horizontal.

In the polyester foam sheet of the present invention, the average light reflectance at a wavelength of 400 nm to 700 nm is preferably 80% or more. By setting it as such a reflectance, it becomes suitable as a light reflection board. As for average light reflectivity, it is more preferable that it is 85% or more, and it is still more preferable that it is 90% or more. Here, light reflectance shows the relative value when the reflectance of a barium sulfate white plate is made into 100%. The reflectance of such light can be achieved by using PTT having a low absorption of light in the above range as a raw material and retaining a large number of fine bubbles without adding a pigment that absorbs such light.

It is desired that the sheet of the present invention has a good color tone. It is preferable that L * which is an index which shows brightness is 80 or more, more than 85 is more preferable, 90 or more is especially preferable in the state which does not color using a pigment and dye. The upper limit of L * is not particularly present, but usually 100 or less. Moreover, it is preferable that b * which is an index which shows yellowness is -5-10, It is more preferable that it is -3-8, More preferably, -2-5.

Moreover, it is preferable that the sheet | seat of this invention is 50-1500 Mpa * cm <3> / g of the value which divided tensile elastic modulus by density. In addition, the tensile modulus of elasticity uses the average value of MD direction and TD direction here. The sheet having such a value facilitates handling while having excellent flexibility. The value obtained by dividing the tensile modulus by density is more preferably 100 to 1200 MPa · cm 3 / g, still more preferably 200 to 1100 MPa · cm 3 / g, and particularly preferably 300 to 1000 MPa · cm 3 / g.

Next, the manufacturing method of the polyester foam sheet which concerns on this invention is demonstrated.

In the polyester foam sheet of the present invention, 50% by weight to 100% by weight of a melt made of polytrimethylene terephthalate (PTT) is mixed by injecting a specific amount of a specific substance in a gaseous state at atmospheric pressure at a melting temperature of the melt. After melt | dissolution, it can obtain by the "special melt extrusion foaming method" which extrudes and shape | molds from a mold under specific conditions, and foams the said injected substance and rapidly cools and solidifies.

Before demonstrating a specific manufacturing method, the said "special melt extrusion foaming method" is demonstrated first.

Substances that are gaseous at atmospheric pressure may be dissolved in the melt of the resin to a saturation concentration. The saturation concentration is lower as the pressure in the system decreases. For this reason, the substance dissolved in high concentration at high pressure is separated from the resin and becomes a bubble when the pressure is lowered and the saturation concentration is lower than the dissolved concentration. At this time, after passing through a supersaturated state for a short time, very small bubble nuclei which first become bubbles are generated, and then bubble nuclei are grown to generate bubbles as large as the supersaturated concentration.

In the "special melt extrusion foaming method", in order to generate a large number of fine bubbles, it is important to generate a large number of bubble cores that cause bubbles and to prevent the bubble cores from growing as much as possible.

In order to generate a large number of bubble nuclei, it is necessary to set the supersaturation concentration to a predetermined value or more, and in order to do this, it dissolves at a high pressure or above a predetermined pressure so that a substance to be a gas becomes a predetermined concentration or more, and in a short time so that dissolved substances do not become bubbles. It is necessary to suddenly lower the saturation concentration by opening the pressure.

In order to prevent the bubble nucleus from growing as much as possible, it is also important not to increase the concentration of the substance to be a gas too high. This is because bubbles grow rapidly if the supersaturation concentration is too high. In addition, the melt that has been pressurized to the normal pressure needs to be cooled and solidified rapidly to suppress the growth of bubbles as much as possible.

In addition, according to the investigation by the present inventors, by using the melt containing PTT as a main component, it becomes easy to make bubbles small more than what is known by conventional PET and PBT. The reason for this is not clear, but it is thought that it may be caused by the zigzag molecular structure of PTT, a moderate degree of polar group concentration, and a relatively low melting temperature.

In addition, in order to make the bubble which is another object of this invention into S / T of a predetermined range, ie, to make a non-flat bubble, it is important not to stretch or compress at the time of manufacturing a sheet | seat. In general, a fine foam sheet of PET, which is used as a light reflection sheet, generates only bubbles by forming foreign matters as nuclei by stretching the solidified sheet. Since the "special melt extrusion foaming method" of the present invention does not require such an extending process, it becomes possible to obtain bubbles which are not flat. However, also in the present invention, it is necessary to be careful not to elongate the sheet from when the bubble is generated by extrusion to winding up.

Below, the manufacturing method of this invention is demonstrated concretely.

The PTT composition can be obtained by a known method. For example, the PTT composition is subjected to a transesterification reaction at atmospheric pressure at a temperature of 180 ° C. to 260 ° C. by a conventional method, using dimethyl terephthalate and trimethylene glycol, and optionally other copolymerization components as a raw material with titanium tetrabutoxide as a catalyst. It can obtain by performing a polycondensation reaction at 220 degreeC-270 degreeC under reduced pressure.

The additives necessary for producing the polyester foam sheet can be added by a method of addition at the time of polymerization, a method of adding melt kneading after polymerization, or a combination thereof, and the like. It can be appropriately selected depending on the performance and the like. When melt-kneading and adding various additives, the PTT composition obtained by superposing | polymerizing can be carried out by cooling and solidifying, or inject | pouring together with various additives etc. in a single screw or twin screw extruder etc. as it is in a molten state.

In the special melt extrusion foaming method, the melt made of PTT is supplied to the supplying PTT composition by using an extruder, the composition is melted by the rotation of a screw, and the melt sent from the extruder is slit-shaped through a heated flow path. Extrusion is carried out from such a detention.

As the extruder, a single screw or twin screw extruder, a tandem extruder in which two or more thereof are connected in series, and the like can be used. The screw of the extruder is preferably used according to the nature of the PTT composition to be applied, the nature of the material gas to be injected. The extruder is preferably set at a temperature at which the cosmetic melt does not remain and the thermal decomposition of the composition can be suppressed, and the melting point of the PTT composition is preferably + 0 ° C to 30 ° C, and the melting point + 0 ° C to 20 ° C. It is more preferable to set it as it, and it is still more preferable to set it as melting | fusing point +0 degreeC-15 degreeC.

If necessary, a filter may be installed between the extruder and the detention to remove foreign substances, a gear pump may be installed to increase the quantitative supply, a stationary mixer may be installed to improve dispersibility of the injected material, or the temperature may be kept constant. In order to install the heat exchange unit. In such a case, it is preferable to select pressure or temperature appropriately so that the substance injected in the vicinity of the apparatus does not become a large bubble. Even when these devices are installed, it is preferable to set at a temperature at which the cosmetic melt does not remain, and pyrolysis of the composition can be suppressed, and it is preferable to set the melting point of the PTT composition at + 0 ° C to 30 ° C.

In the special melt extrusion foaming method, a substance in a gaseous state is injected into the melt at ordinary pressure at a melting temperature. In consideration of ease of handling, the substance to be injected is preferably in a gas state at room temperature and atmospheric pressure. Specific examples include inert compound blowing agents such as nitrogen, carbon dioxide, helium, argon, water, ethane, propane, butane, ethylene, propylene, petroleum ether, pentane, hexanes, heptanes, toluene, trichloromethane, tetrachloromethane, Aliphatic hydrocarbon blowing agents such as trichlorofluoromethane, methanol, 2-propanol, isopropyl ether, methyl ethyl ketone, methyl chloride, dichloroethane, chloroform, fluoromethane, difluoromethane, trifluoroethane, chlorotrifluoro Romethane, dichlorodifluoromethane, fluorochloroethane, dichlorotetrafluoroethane and the like.

Specific examples of the fluorocarbons include Clon (Freon of the CFC series such as Flon (R-11, R-12), Alternative Flon (R-134a), CFC-11, CFC-12, CFC-113, CFC-114, etc.). ) Halogenated hydrocarbon blowing agents and the like. Among these, nitrogen, helium, argon and water are preferable from the viewpoint of not advancing the crystallization of the sheet and reducing the bubble size, and particularly preferably nitrogen.

In order to inject | pour such a substance, it is necessary to set it as 0.01 weight%-3 weight% from a viewpoint which refines a bubble and improves the surface state of a sheet | seat. 0.02 weight%-1 weight% are more preferable, and 0.05 weight%-0.5 weight% are more preferable.

Any time may be used as the method of injecting, as long as it is between the extruder and the apparatus, but injecting in an extruder is preferable because the substance can be injected uniformly in a melt.

The melt is then extruded from the mold to be shaped into a sheet-like shape, while at the same time the pressure is released and the injected material is bubbled. Although it can be suitably selected according to the shape of the sheet | seat made into the objective, in order to obtain a sheet of uniform thickness, it is preferable to use linear slits, such as T die and I die, or cylindrical slits called annular die. desirable. The structure of the mold is preferably designed so that foaming does not occur in the mold. For this purpose, the pressure of the melt at the inlet is required to be 5 MPa or more, preferably 10 MPa or more, more preferably 12 MPa, even more preferably 15 MPa or more. Although there is no upper limit in particular, it is preferable to set it as the extrusion pressure of 100 MPa or less in consideration of the structure of an installation, and it is more preferable to set it as 50 MPa or less.

It is preferable to set the detention temperature at the time of extrusion in the range which does not solidify a melt, Specifically, it is preferable to set it as melting | fusing point +0 degreeC-30 degreeC, and it is more preferable to set it as melting | fusing point +0 degreeC-20 degreeC It is preferable to set it as melting | fusing point +0 degreeC-15 degreeC, and it is preferable to set as low as possible in the range which extrudates a melt uniformly.

In the special melt extrusion foaming method, the melt formed and foamed into a sheet shape is subsequently cooled and solidified. However, in the present invention, it is necessary to rapidly cool and solidify the bubbles so that the enlargement of the bubbles is suppressed. As a result, it becomes possible to make the bubble diameter of the foam sheet of this invention small. As used herein, "quickly" refers to cooling the sheet so as to have thermal properties. Specifically, the time for cooling the sheet below the crystallization temperature after extruding from the mold is preferably within 60 seconds, and within 40 seconds. It is more preferable, and it is especially preferable to set it within 20 second. In the case of obtaining an amorphous sheet, it is particularly important to cool and solidify rapidly.

As a method of achieving such cooling solidification, a method of bringing the melt into contact with a solid such as a cooling roll or a cooling belt controlled below the crystallization temperature of the PTT composition, a method of bringing the sheet into contact with a liquid such as water, a method of combining them, and the like This is listed. Among these, the method which casts (arranges) the melt extruded from the slit-shaped mold | base on a roll or a belt, and then puts in water and rapidly solidifies cooling is most preferable.

It is preferable that solids, such as a cooling roll and a belt, are made of metal with favorable thermal conductivity. As for the temperature of the solid and liquid to contact, 0 degreeC-50 degreeC are more preferable, 0 degreeC-30 degreeC are further more preferable, and 0 degreeC-20 degreeC is especially preferable. It is preferable to set it as 0.05 second-10 second, as for the time until extruded from a mold and contacting a solid or a liquid, It is more preferable to set it as 0.1 second-5 second, It is especially preferable to set it as 0.2 second-2 second.

In addition, in this invention, it is necessary to be careful not to elongate a sheet | seat until the sheet | seat which foam | bubble generated by extrusion is wound up. For this purpose, it is preferable to make the winding speed into 10 times or less of the linear speed of the melt | dissolution from a die, More preferably, it is 8 times or less, More preferably, 5 times or less is good. On the other hand, the lower limit is a speed ratio at which the sheet becomes flat, specifically 0.9 times or more is preferable, 0.95 times or more is more preferable, and 1.0 times or more is more preferable. By setting it as such a speed ratio, it becomes easy to make S / T into a predetermined range.

In the polyester foam sheet of the present invention, a specific amount of a gaseous substance at a normal temperature and normal pressure is injected into an amorphous sheet made of a resin composition in which 50% by weight to 100% by weight is polytrimethylene terephthalate, and then the sheet is quickly It can also be manufactured by the "special solid foaming method" which foams the said injected | poured substance by heating with the furnace. In this case, however, only the crystallized sheet is obtained.

Before demonstrating a specific manufacturing method, the above-mentioned "special solid foaming method" is demonstrated first.

Substances that are gaseous at atmospheric pressure may be dissolved in the amorphous sheet up to the concentration according to the gas pressure. The dissolved concentration decreases as the pressure in the system decreases. In the "special melt foaming method", when the saturation concentration is lower than the dissolved concentration, the resin is separated from the resin to form bubbles, but in the solid, it is gradually released from the surface and does not become bubbles. However, when the sheet is at a temperature above the glass transition point, bubbles are formed as in the melt.

In the "special solid foaming method", in order to generate a large number of fine bubbles, it is important to generate a large number of bubble cores that cause bubbles and to prevent the bubble cores from growing as much as possible.

In order to generate a large number of bubble nuclei, a large amount of bubbled material is injected at a high pressure at a predetermined pressure or higher so that a substance to be a gas becomes higher than a predetermined concentration, and the sheet is quickly moved to a glass transition point or higher so that the injected material is not discharged from the surface. It is necessary to set it as temperature.

In order to prevent the bubble nucleus from growing as much as possible, it is also important not to increase the concentration of the substance to be a gas too high. This is because bubbles grow rapidly when the concentration is too high.

In addition, since PTT has a faster crystallization rate than PET, it is important to rapidly increase the temperature of the sheet. In addition, since PBT has extremely high crystallization rate, an amorphous sheet cannot be obtained, and a foam sheet cannot be obtained in the same manner.

In addition, in order to make the bubble into S / T of a predetermined range, ie, a bubble without flatness, which is another object of this invention, it is important not to stretch or compress at the time of manufacturing a sheet | seat. Since the "special solid foaming method" of this invention does not require an extending | stretching or a compression process, it becomes possible to obtain a bubble which is not flat. However, also in the present invention, it is necessary to be careful not to elongate the sheet after the sheet is heated to generate bubbles.

Below, the "special solid foaming method" of this invention is demonstrated concretely.

Specific examples of the gaseous substance at room temperature and atmospheric pressure injected into the sheet in the special solid foaming method include inert compound blowing agents such as nitrogen, helium and argon, ethane, propane, butane, ethylene, propylene, petroleum ether, pentane, hexane and heptane. Toluene, trichloromethane, tetrachloromethane, trichlorofluoromethane, methyl chloride, dichloroethane, fluoromethane, difluoromethane, trifluoroethane, chlorotrifluoromethane, dichlorodifluoromethane, Fluorochloroethane, dichlorotetrafluoroethane and the like. Among these, nitrogen, helium, and argon are preferable from a viewpoint of making bubble size small, and nitrogen is especially preferable.

In order to inject | pour this substance, it is necessary to set it as 0.01 weight%-3 weight% from a viewpoint of making a bubble fine. 0.02 weight%-1 weight% are more preferable, and 0.05 weight%-0.5 weight% are more preferable.

As a method of injecting, it can achieve by putting an amorphous sheet for 10 minutes or more in the said gas atmosphere whose pressure is 0.5 Mpa or more. 10 MPa or more is more preferable, and 15 MPa or more is more preferable. Moreover, 30 minutes or more are more preferable, 60 minutes or more are more preferable, and 120 minutes or more are especially preferable. When injecting gas, the temperature of the sheet is preferably 40 ° C. or lower, preferably 20 ° C. or lower, and more preferably 10 ° C. or lower so as not to crystallize.

The sheet injecting such a gas is rapidly heated to 60 ° C to 200 ° C to foam the injected material. Here, quickly means that the injected gas does not fall below the above amount. 100 degreeC-200 degreeC is more preferable, and 120 degreeC-200 degreeC of the temperature to heat is more preferable. At this time, in order to foam, it is important to rapidly heat the foam before foaming. Such heating can be achieved by immersing in a heated inert liquid or by contacting a heated roll.

In the polyester foam sheet of this invention, an amorphous thing can be formed into a foamed molded object by shape | molding.

The molded foam is preferably crystallized at the time of molding. By doing in this way, heat resistance can be improved. As for the degree of crystallization, it is preferable that no exothermic peak derived from crystallization is observed between 0 ° C and 150 ° C when the polyester foam sheet is thermally analyzed by an input compensation type differential calorimeter (DSC).

The apparent density of the polyester foam sheet is preferably 0.05 g / cm 3 to 1.25 g / cm 3, more preferably 0.1 g / cm 3 to 1 g / cm 3, and further preferably 0.15 g / cm 3 to 0.8 g / cm 3. It is preferable and it is especially preferable that they are 0.2 g / cm <3> -0.7g / cm <3>.

The shape of the molded body can be appropriately selected depending on the application. For example, box shape, cup shape, corrugated board shape, etc. are mentioned. As a method of molding such a molded article, press molding, straight molding, drape molding, plug assist molding, vacuum molding, vacuum pressure molding, pressure molding, and the like are enumerated. Among these, vacuum pressure molding is more preferable.

When forming, it is preferable to first heat the sheet at a temperature of 30 ° C to 80 ° C by means such as heater radiation or a heating plate. By doing so, it is easy to soften the sheet without crystallizing and the moldability and transferability are improved. 40 degreeC-70 degreeC is more preferable, 45 degreeC-65 degreeC is further more preferable, and 50 degreeC-60 degreeC is especially preferable.

Next, the sheet is brought into contact with the mold to be molded, but the mold temperature at this time is preferably 60 ° C to 180 ° C. In the present invention, the polyester foam sheet is almost amorphous at the time of shaping in order to secure moldability, but it is important to crystallize the molded body in order to ensure heat resistance after shaping. For this purpose, it is preferable to control the mold temperature to a certain temperature range to crystallize the molded body. 65 degreeC or more is preferable in order to provide sufficient heat resistance to the said molded object, and in order to suppress mold release or bubble crushing from a metal mold | die after shaping | molding, it is preferable to set it as 180 degrees C or less. The mold temperature is more preferably 80 ° C to 160 ° C, and particularly preferably 100 ° C to 150 ° C. It is also one of the preferable methods to raise the temperature of a metal mold | die after heating, or to heat it from the exterior, and to make a sheet into the temperature of the said range.

In this invention, heat shaping | molding can also carry out 2 or more sheets of polyester foam sheets. At this time, it is preferable to form an air escape hole in the sheet on the side where the pressure increases during molding so that air between the sheets is easily released.

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

As a function required for these light reflection boards, what has the 1st high reflectance, especially high diffuse reflection is mentioned. The polyester foam sheet of the present invention contains a large number of fine bubbles such as an average bubble size of 0.01 μm to 50 μm so as to have an apparent density of 0.05 g / cm 3 to 1.25 g / cm 3, and the sheet is not colored. That is, the low light absorption achieves high reflectivity, especially high diffuse reflectivity.

Secondly, those that can be processed into a shape corresponding to the light source and which can maintain this shape are listed. It is preferable that the processing can be easily processed (which can be processed even with a small force), and the processing range is wide, that is, the processing can be performed in various shapes.

The light reflection plate of the present invention has preferred flexibility. In order to express only the flexibility, it is possible to reduce the thickness of the sheet. However, in this case, the rigidity is excessively eliminated, and the force for maintaining the shape is weakened, and the deformation may be caused by changes in the environment or slight external force. If it is deformed, light cannot be reflected in a desired direction, and in the case of a liquid crystal display panel, contrast is generated on the screen. The light reflector of the present invention is composed of polytrimethylene terephthalate having 50 to 100% by weight of crystal flexibility coming from a zigzag molecular skeleton structure, and also contains a large number of fine bubbles as described above. It is made of a honeycomb structure made of thin bulkheads, so it is flexible without thinning. As a result, flexibility, that is, workability and rigidity can be made compatible.

In addition, the light reflection plate of the present invention is composed of polytrimethylene terephthalate having 50% by weight to 100% by weight of elastic recovery of crystals coming from a zigzag molecular skeleton structure, and S / T of 0.05 to 10, the average When the bubble size is 0.01 μm to 50 μm, it contains a large number of fine bubbles that are not flat, and thus becomes a honeycomb structure that is difficult to be crushed. Therefore, it has a high elastic recovery property and is processed into a shape such as a curved surface without bending or wrinkles. It is easy. Moreover, even if a process fails to some extent, the possibility of returning to an original form and processing again is high.

This property is unexpected from a light reflector made of a conventional PTT sheet or a PET fine foam sheet.

The light source is linear, such as a fluorescent lamp, a large dot, such as an incandescent lamp, a small dot, such as an LED, or a single light source, or a combination of many. What can be made into various shapes is very desirable. When bending or wrinkles occur, not only the light cannot be reflected in a desired direction, but also the reflectance of the wrinkles is lowered, resulting in a light and shade of stripe shape in the case of a liquid crystal display panel.

It is preferable that the average light reflectivity in wavelength 400nm-700nm is 80% or more, as for the light reflection board of this invention, 85% or more is more preferable, 90% or more is especially preferable.

The thickness is preferably 100 µm to 2 mm, more preferably 200 µm to 1.5 mm, particularly preferably 500 µm to 1.2 mm in consideration of handling, rigidity at the time of installation and hiding of light.

The light reflection plate preferably has heat resistance because the light source generates heat, and for this purpose, the crystalline one is preferable. As an index of crystallinity, it is an indicator whether the exothermic peak derived from crystallization is observed between 0 ° C. and 150 ° C. when thermal analysis is performed with an input compensated differential calorimeter, but the exothermic peak area is preferably 5 J / g or less. 3 J / g or less is more preferable, 1 J / g or less is more preferable, and of course it is most preferable that no observation is made at all.

Although the shape of a light reflection board is selected according to a light source, plate shape, wave plate shape, box shape, etc. are mentioned. In addition, conical, angular and bowl shapes which can cover light around the light source and reflect light in one direction are also preferable shapes.

Processing into such a shape can be performed by trimming, bending, pressing, thermoforming, etc. by slit, cutting, mold, etc., but in the case where heat resistance is required or when self-support of shape is required It is preferable to perform thermoforming. This is because the deformation part is heat-set by thermoforming so that the dimensional accuracy is excellent.

Example

EMBODIMENT OF THE INVENTION Hereinafter, although embodiment of this invention is described in detail based on an Example, this invention is not limited to these Examples. The main measured value in this invention was measured with the following method.

(1) Polytrimethylene terephthalate (PTT) content rate, BPE content rate:

PTT content (% by weight) is a sheet 100g HFIP: was obtained was dissolved in 1, the insoluble component using the solution after filtration with MEMBRANE FILTER (1㎛, PTFE) by 1H-NMR measurement: CDCl ₃ = 1. The measuring instrument used FT-NMR DPX-400 (manufactured by Bruker). Insoluble components removed by filtration were used to determine the PTT content by measuring the weight after vacuum drying.

(2) intrinsic viscosity [η]:

Intrinsic viscosity [η] is obtained by using Ostwald viscometer to extrapolate ratio ηsp / C of specific viscosity ηsp in o-chlorophenol and concentration C (g / 100 milliliters) to zero concentration. Obtained by

[1]

(3) carboxyl terminal concentration:

1 g of PTT composition was dissolved in 25 mL of benzyl alcohol, after which 25 mL of chloroform was added, followed by titration with 1/50 N potassium hydroxide benzyl alcohol solution, and from titration value VA (mL) and blank value V0 in the absence of PTT composition. It calculated | required according to the following two formulas.

[Number 2]

Carboxyl Terminal Concentration (eq / ton) = (VA-V0) × 20

(4) apparent density:

The polyester foam sheet was dried at 50 degreeC, and it calculated | required by dividing the weight when the weight value was reached. In addition, the volume was calculated | required by immersing a sheet in water.

(5) Exothermic peak from crystallization:

The presence or absence of the exothermic peak from crystallization and the exothermic peak area were maintained at 0 ° C. for 3 minutes using a Pyris 1 (with a cooling unit) manufactured by Perkin Elmer as a differential compensation calorimeter (DSC). It heated up from 0 degreeC to 260 degreeC at the temperature increase rate of ° C / min, and observed by thermal analysis.

(6) Peak time of isothermal crystallization:

The peak time for isothermal crystallization is 0 ° C using Pyris 1 (with a cooling unit) manufactured by Perkin Elmer as a compensating differential calorimeter (DSC) of the composition obtained by quenching and solidifying the melted sheet at 280 ° C in liquid nitrogen. After hold | maintaining for 3 minutes, it heated from 0 degreeC to X degreeC at the preset temperature increase rate of 500 degreeC / min, hold | maintained at X degreeC, and measured and calculated | required the time when the endothermic amount resulting from crystallization shows a peak.

(7) Ratio S / T of the average diameter of bubbles and the average size (S) in the plane direction and the average size (T) in the thickness direction:

The ratio S / T between the average diameter of bubbles and the average size (S) in the plane direction and the average size (T) in the thickness direction is a sheet in both directions in the MD direction (sheet longitudinal direction) and TD direction (sheet width direction). The cross section was calculated | required using image analysis software from the cross section image observed using the scanning electron microscope (it abbreviates as "SEM" hereafter). Planetron Inc. as image analysis software. Image-Pro Plus ver.4.0 was used. The average diameter of the bubble was obtained by averaging the average value of the lengths projected on the major and minor axes of the corresponding ellipse approximating the cross section of the bubble to the ellipse in each of the directions of the MD direction and the TD direction. In addition, S and T are the average values of the height and width of the bubble's circumscribed rectangle (the minimum rectangle which completely encloses the entire bubble and has sides parallel to the sheet direction of the sheet) with respect to the MD and TD directions, respectively. It calculated | required on average.

(8) Heat Shrinkage:

Based on JIS K7133, the dimensional change at the time of heat-processing a film without applying tension in 150 degreeC for 30 minutes was measured, and thermal contraction rate was calculated | required.

(9) Average light reflectance:

The average light reflectance was determined by shifting the incident angle by 8 ° using UV-2200 manufactured by Shimadzu Corporation, measuring the total reflectance at wavelengths of 400 nm to 700 nm every 10 nm, and calculating the average value thereof. At this time, the measuring apparatus was adjusted to make barium sulfate powder 100%.

(10) hue (L level, b * value):

Measurements were made using a color computer from Suga Test Instruments.

(11) Flexibility-1:

The state when the sheet was bent to 180 ° C was observed. What was broken was evaluated as "(circle)", the thing which a crack generate | occur | produced on the surface in "(triangle | delta)", and the thing which neither a break nor a crack generate | occur | produced as "(circle)".

(12) Flexibility-2:

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

(13) Machinability:

The processing state when the bending process of curvature 3mm (phi) was performed was observed. "X" was evaluated as "(circle)" and that which was not bent and wrinkles did not generate | occur | produce as "(circle)" that it did not become desired curvature and had wrinkles on the surface.

Example 1

Ciba Specialty Chemicals as a thermal stabilizer of 1 part by weight of PTFE having an average particle diameter of 5 µm to 98.8 parts by weight of PTT having an intrinsic viscosity [η] of 1.3 dl / g, a carboxyl terminal concentration of 10 eq / ton, and a BPE content of 0.5% by weight. 0.1 parts by weight of Irgafos 168 in the product and 0.1 parts by weight of Irganox 1098 in Ciba Specialty Chemicals as a trapping agent for low molecular weight volatiles were supplied to a 50 mmφ single screw extruder having a melting point of 225 ° C. After melt | dissolving and melt | dissolving, it extruded at the speed | rate of 5 m / min from the T die | dye of width 100mm and a space | interval 0.5mm as a shaping | molding through the flow path heated at the same temperature as an extruder, and shape | molded in the sheet form.

At this time, 0.1 weight% of nitrogen was inject | poured from the middle of the said extruder with respect to a composition, and it mixed and melt | dissolved with the melt. In addition, the pressure of the melt at the T die inlet was 15 MPa. The melt extruded from the T-die was cast on a metal rotary roll 50 mm apart, then introduced into cooling water to cool and solidify to obtain a foam sheet. At this time, the rotating roll and the cooling water are controlled to be 10 ° C, the time until the melt is extruded and contacted with the rotating roll is 0.6 seconds, the time until cooling to 68 ° C or less of the crystallization temperature of the composition is It was within 20 seconds.

The obtained polyester foam sheet had a thickness of 1 mm and a width of 100 mm, and the sheet was not cracked even when bent at 180 degrees. The intrinsic viscosity [η] is 1.15 dl / g, the carboxyl terminal group concentration is 15 eq / ton, the BPE content is 0.5% by weight, the density is 0.6 g / cm 3, the average bubble diameter is 20 μm, and (S / T) is It had a fine and non-flat bubble at 1.3, was excellent in light reflectance at 85%, and had a small heat shrinkage at 0.2% in both MD / TD directions. In addition, it was thought that the heat of crystallization was 15 J / g and the peak time of isothermal crystallization had good thermoforming for 1 second to 60 seconds over the whole range of 100 degreeC-150 degreeC.

The obtained polyester foam sheet was shape | molded by the vacuum pressure forming method, and the cup-shaped molded object of 200 mm of internal diameters and 50 mm of depth was obtained. The molding was first performed by heating the sheet at 55 ° C. with heater radiation, then contacting the aluminum mold heated at 120 ° C. with a vacuum degree of 720 mmH and a pressurization pressure of 0.2 MPa, shaping and crystallizing it as it was for 120 seconds. The obtained foamed molded article was a lightweight molded article having an apparent density of 0.6 g / cm 3. The results are shown in Tables 1 and 2 below.

In addition, "ME" in the table means a special melt extrusion foaming method, "S" means a special solid foaming method, and "COOH" means a carboxyl terminal group concentration. In addition, the value described in the item of "thermal contraction rate" means the value in MD / the value in TD, respectively.

EXAMPLES 2-4

The polyester foam sheet was obtained like Example 1 except having changed the conditions shown to the following Tables 1 and 2. The results are shown in Tables 1 and 2 below. In any case, it was a polyester foam sheet having excellent lightness and flexibility within the scope of the present invention.

In Example 2, by increasing the discharge pressure and adding a large amount of PTFE particles having a small particle size, a favorable polyester foam sheet having finer bubbles and high light reflectance was obtained.

In Example 3, the gas injection amount was increased, and in Example 4, the thickness of the sheet was changed, but a polyester foam sheet excellent in the same manner as in Example 1 was obtained.

Example 5

Polyester in the same manner as in Example 1 except that PTT having an intrinsic viscosity [η] of 0.9 dl / g, a carboxyl end group concentration of 20 eq / ton, and a BPE content of 0.5 wt% was used and the thickness was 0.7 mm. A foam sheet was obtained. At this time, the gap between the T dies was adjusted so that the pressure of the melt at the T die inlet was 20 MPa or more. The results are shown in Tables 1 and 2 below. The obtained polyester foam sheet was in the scope of the present invention, and had excellent light weight, flexibility, and light reflectance.

Example 6

A polyester foam sheet was obtained in the same manner as in Example 1, except that 3 parts by weight of a fluorine mica (SOMASIF MAE manufactured by Coop Chemical Co., Ltd.) having an average particle diameter of 6 µm was used instead of PTFE. At this time, the gap of the T die was adjusted so that the pressure of the melt of the T die inlet might be 15 MPa or more. The results are shown in Tables 1 and 2 below. The obtained polyester foam sheet was in the scope of the present invention, and had excellent light weight, flexibility, and light reflectance.

EXAMPLES 7, 8

5 parts by weight of PTFE having an average particle diameter of 2 μm to 94.8 parts by weight of PTT having an intrinsic viscosity [η] of 1.15 dl / g, a carboxyl terminal concentration of 15 eq / ton, and a BPE content of 0.5% by weight, Ciba Specialty Chemicals as a heat stabilizer A 0.4 mm thick unfoamed sheet made of a PTT composition having a melting point of 225 ° C., containing 0.1 parts by weight of Irgafos 168 in the product and 0.1 parts by weight of Irganox 1098 in Ciba Specialty Chemicals as a trapping agent for low molecular weight volatile impurities. In the seventh embodiment, the temperature was kept at 20 ° C. or lower and 120 minutes was injected into a nitrogen atmosphere at 20 MPa to inject 0.2 wt% of nitrogen. In Example 8, 100 minutes in an argon atmosphere of 15 MPa was maintained at a temperature of 20 ° C. or lower. After injecting 0.2% by weight of argon. After taking out, it heated rapidly and foamed by putting into 180 degreeC oil bath within 3 minutes, and obtained the polyester foam sheet. The results are shown in Tables 1 and 2 below. All the obtained polyester foam sheets were in the range of this invention, and had the outstanding lightness, flexibility, and light reflectance.

[Comparative Examples 1 and 2]

Instead of 95 parts by weight of PTT, in Comparative Example 1, 95% by weight of PET having an intrinsic viscosity [η] of 0.85 dl / g and a carboxyl terminal concentration of 30 eq / ton, and 5 parts by weight of talc having an average particle diameter of 5 μm, Comparative Example 2 In the same manner as in Example 1 except that 95 parts by weight of PBT having an intrinsic viscosity [η] of 1.0 dl / g and a carboxyl end group concentration of 50 eq / ton was used and 5 parts by weight of talc having an average particle diameter of 5 µm. A sheet was obtained. Moreover, in the comparative example 2, the temperature of an extruder, T-die, etc. was set to 30 degreeC high compared with the said Example 1. The results are shown in Tables 1 and 2 below.

The sheet of Comparative Example 1 had a large bubble diameter and was low in light reflectance. Moreover, the sheet | seat of the comparative example 2 also had a big bubble diameter, and was not only low light reflectivity, but also when it fell to 180 degrees, it split into two and inferior to flexibility.

Comparative Example 3

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

[Comparative Example 4]

A foam sheet was obtained in the same manner as in Example 7, except that 0.8 wt% carbon dioxide gas was press-fitted in the state where the temperature was maintained at 20 ° C. or lower using 4 MPa carbon dioxide gas instead of nitrogen. However, foaming was not seen even in an oil bath at 180 ° C. The results are shown in Tables 1 and 2 below.

[Comparative Example 5]

A roll of a non-oriented amorphous sheet having a thickness of 250 μm and a polyethylene nonwoven fabric wrapped in PET as used in Comparative Example 1 and a polyethylene nonwoven fabric was wound for 48 hours in acetone vapor at atmospheric pressure, and then taken out. Impregnation time. Then, it foamed in the heating furnace set to 200 degreeC, and obtained foam seat | seet. The foam sheet thus obtained was a foam sheet having a thickness of 1 mm, an apparent density of 0.4 g / cm 3, an average bubble diameter of 3 µm, and an S / T of 1.2 and a light reflectance of 90%. When the sheet was evaluated in the same manner as in the film of the present invention and evaluated for its flexibility and workability, bending was not easy, and when bending at a curvature of 3 mmφ, a large number of wrinkles occurred.

Example 9

Using the sheets of Examples 1 and 2 and Comparative Examples 1 and 3, a backlight unit for a 26-inch liquid crystal display panel was manufactured. As the light source, 16 cold cathode tubes were used, and foam sheets of Examples 1, 2 and Comparative Example 3 were used as light reflecting plates having a wave shape as shown in FIG. 1 by vacuum molding. In addition, in FIG. 1, the cold cathode tube was arrange | positioned on the 5 mm center of the recessed part of the lower surface of foam seat | seet. On the other hand, since the sheet | seat of the comparative example 2 was difficult to process, it used as a flat-plate light reflection board, and the cold cathode tube was arrange | positioned on the sheet | seat 5 mm at the above intervals. On the light source, a diffuser plate (Delaglass DS manufactured by Asahi Kasei Chemicals Corporation) having a thickness of 1.5 mm was installed to form a backlight unit.

When the light reflection board which consists of sheets of Examples 1 and 2 was used, it had high brightness | luminance, and the luminance deviation originating in a cold cathode tube was not confirmed.

On the other hand, in the case of using the light reflection plates made of the sheets of Comparative Examples 1 and 2, not only the luminance was lowered as compared with Examples 1 and 2, but also the luminance deviation of the stripe shape derived from the cold cathode tube was visually confirmed. In particular, in Comparative Example 2, the luminance deviation was remarkable.

In addition, when the backlight unit using the light reflection plate of Comparative Example 1 was turned on for 10 hours, the temperature locally rose to 80 ° C., but no deformation was observed in the light reflection plate.

Although this invention was further demonstrated with reference to the specific embodiment in detail, it is clear for those skilled in the art that various changes and correction can be added without deviating from the mind and range of this invention.

This application is based on the JP Patent application (Japanese Patent Application No. 2006-011194) of an application on January 19, 2006, The content is taken in here as a reference.

The polyester foam sheet of the present invention has excellent flexibility, heat insulation, light weight, and light reflectivity. For this reason, it is useful for various uses, such as a food container, a packaging material, a building material, a light reflection board, as an application example of this invention. In addition, in the case of the light reflecting plate, it has excellent light reflectivity and diffuse reflectivity, and has a punching process and a bending processability that can be easily processed without wrinkles in a shape suitable for a light source. It is useful as a light reflection board of lighting fixtures.

Claims (15)

As polyester foam sheet: 50 to 100% by weight of polytrimethylene terephthalate, Apparent density is 0.05-1.25g / cm3, Including the bubble whose average bubble size is 0.01-50 micrometers, The ratio (S / T) of the average size (S) of the bubble direction to the average size (T) of the thickness direction is 0.05-10, The polyester foam sheet characterized by the above-mentioned. The polyester foam sheet according to claim 1, wherein the polyester foam sheet has a thickness of 1 µm to 10 mm. The average bubble size of the bubble is 0.01 to 30 µm, and the ratio (S / T) of the average size S in the plane direction of the bubble to the average size T in the thickness direction. ) Is 0.7 to 3 polyester foam sheet. The polyester foam sheet according to any one of claims 1 to 3, wherein the thermal contraction rate at 150 ° C of the polyester foam sheet is -2 to 5%. The polyester foam sheet according to any one of claims 1 to 4, wherein the average light reflectance of the polyester foam sheet with respect to light having a wavelength of 400 to 700 nm is 80% or more. The polyester foam sheet according to any one of claims 1 to 5, which is produced by a melt extrusion method. The polyester foam sheet according to any one of claims 1 to 6, wherein an exothermic peak derived from crystallization is observed between 0 and 150 ° C in thermal analysis by an input compensated differential calorimeter. The polyester foam according to any one of claims 1 to 7, wherein a temperature at which the peak time of isothermal crystallization of the polyester foam sheet is 1 to 60 seconds is present in a range of 100 to 150 ° C. Sheet. The light reflection board comprised from the polyester foam sheet of any one of Claims 1-8. 10. The light reflecting plate according to claim 9, wherein an exothermic peak derived from crystallization observed between 0 and 150 ° C in thermal analysis by an input compensated differential calorimeter is 0 to 3 J / g. Into a melt containing 50 to 100% 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 was mixed and dissolved to obtain a melt. And extruding the melt from the mold at an extrusion pressure of 5 to 100 MPa, and foaming and cooling the injected material to produce a polyester foam sheet. 12. The method of claim 11, wherein the material to be injected is a gaseous state at room temperature and atmospheric pressure. The polyester according to claim 11 or 12, wherein the melt is extruded from a slit-like mold, and then the melt is cast on a metal roll or belt, and then the melt is put into water for cooling and solidification. Method for producing foam sheet. 0.01 to 3% by weight of a gaseous substance at room temperature and normal pressure is injected into an amorphous sheet composed of a resin composition containing 50 to 100% by weight of polytrimethylene terephthalate, and then the amorphous sheet is heated to 60 to 200 ° C for the injection. Process for producing a polyester foam sheet, characterized in that the foaming of one material. The method for producing a polyester foam sheet according to claim 11, wherein the substance to be injected is nitrogen.

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