JP2008088209A - Polyester resin composition foam sheet and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester resin composition foam sheet having excellent surface appearance, lightweight property, shape formability, rework property and optical reflectivity, and to provide a method for producing the same. <P>SOLUTION: This polyester resin composition foam sheet which comprises a polyester resin composition comprising (A) 60 to 99.8 wt.% of a crystalline polyester resin, (B) 0.1 to 20 wt.% of a foaming nucleating agent, and (C) 0.1 to 20 wt.% of a thickener is characterized in that the foam sheet satisfies the following (1) to (2). (1) Melt retention stability is ≤2% under a condition of (the melting point of the foam sheet +45°C). (2) The average pore diameter of the foam sheet in a take-off direction and in a rectangular direction is 0.1 to 50 μm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a thermoplastic polyester resin composition foam sheet and a method for producing the same, and in particular, to a crystalline polyester, comprising a polyester resin composition in which a specific amount of a foam nucleating agent and a thickener are blended, and having a specific range. The present invention relates to a microfoamed sheet having melt residence stability and a bubble diameter, and a method for producing the same. More specifically, it has excellent flexibility, lightness, shape retention, and rework by having fine bubbles inside. The present invention relates to a finely foamed sheet made of the above resin composition, which has excellent properties and light reflectivity, and excellent sheet appearance, and a method for producing the same.

In general, a foam made of a thermoplastic resin is widely used for a heat insulating material, a shock absorbing material, a food container, and the like by taking advantage of its excellent light weight, thermal conductivity, and shock absorbing property. In particular, extruded products such as films and sheets have excellent characteristics in terms of mechanical properties and optical reflection performance. As materials for various applications such as food containers, daily necessities packaging containers, packaging materials, building materials, optical reflectors, etc. Expected.
In these applications, in order to obtain excellent flexibility, heat insulation, light weight, and light reflection function, there has been a strong demand for a sheet or film containing very fine bubbles inside such as several tens of μm or less. In recent years, as a reflector for large-sized liquid crystal televisions, which are particularly growing rapidly, high optical reflectivity and shape shaping of a light reflecting sheet are required for the purpose of improving display brightness and eliminating brightness unevenness. Furthermore, as the size of displays increases, sheet weight and shape retention are also required.

Conventionally, as a polyester resin composition foam sheet containing fine bubbles inside, after forming a film by finely dispersing a polyethylene terephthalate (PET) resin and an incompatible resin therein, the film is uniaxial or biaxial. A polyester film in which fine cavities with an incompatible resin as a core are formed by stretching is known (see, for example, Patent Document 1).
In addition, after containing carbon dioxide gas in a PET sheet roll in a high-pressure vessel, the fine particles with an average cell diameter of 50 μm or less were obtained by heating to 240 ° C. and foaming the contained gas. There is also a proposal for a thermoplastic polyester foam having a heat of 200 μm or more and a specific gravity of 0.7 or less (see, for example, Patent Document 2).

Also, PTFE powder is added to a thermoplastic polyester resin modified with a cross-linking agent, melted and kneaded while removing volatile components with a vent in a twin-screw extruder, and then a foaming agent is pressed into the melt and extruded and foamed. A method for producing a thermoplastic polyester foam obtained by this method has been proposed. (For example, refer to Patent Document 3).
Further, 30% by weight or more is a trimethylene terephthalate unit, and an apparent density composed of a trimethylene terephthalate polymer (PTT resin) having a specific intrinsic viscosity and a terminal carboxylic acid amount is 0.001 g / cm ³ to 1. There is also a proposal of a foam of 2 g / cm ³ (see, for example, Patent Document 4).

Japanese Patent No. 3018539 Japanese Patent No. 2925745 JP 09-70871 A JP 2002-226619 A

However, in the above-mentioned foamed film of Patent Document 1, since bubbles are formed by stretching in the film forming process, the film has undergone orientation crystallization, the elongation is low, and the formability is poor. Have. In addition, the foamed film has a structure in which resin is laminated in the film surface direction and has air bubbles such as gaps, so that the air bubbles are easily crushed when bent or when force is applied from the surface direction. Also, there is a drawback that creases and scratches are easily attached. Furthermore, only a thin film that can be stretched can be obtained, and it is difficult to stand as a molded body.

Further, according to the study by the present inventors, the foamed sheet obtained by the technique of Patent Document 2 is difficult to be shaped because the sheet crystallizes when gas is contained. Further, even if this technology is applied to polytrimethylene terephthalate (hereinafter abbreviated as PTT) as it is, crystallization proceeds before PTT foams, so that foaming is difficult. I can't get it. Moreover, since the manufacturing method of the foam sheet of patent document 2 is a batch type process, the point that manufacturing cost becomes high is also a problem.
In the technique of Patent Document 3, a foamed material is formed by press-fitting a foaming agent such as butane into a molten resin composition composed of a thermoplastic polyester modified with a crosslinking agent and PTFE, and extrusion-foaming. Have gained. However, the foams obtained by these techniques have a low apparent density, and the bubbles cannot be miniaturized, so that the required characteristics cannot be sufficiently satisfied with respect to optical reflectivity and shape retention. .

Moreover, in the technique of patent document 4, the carbon dioxide, n-butane, etc. are inject | poured and melt | dissolved with respect to PTT, and the foam is obtained. However, in these techniques, since the melt viscosity of the foam is low, the resin pressure of the die is low, and it is difficult to make the bubbles fine, and the above-described problems cannot be solved.
In addition, crystalline polyester resins, represented by PTT, cause molecular weight reduction due to thermal decomposition and hydrolysis during melt residence, and the melt viscosity is significantly reduced. Therefore, the sample once foamed and extruded is reworked (melted again and foamed). It was difficult to do.
As described above, the conventional technology cannot obtain a foam sheet having fine pores having excellent flexibility, lightness, shape retention, shape shaping, reworkability and light reflectivity. was there.

  The present invention solves the above-mentioned problems, and its purpose is to exhibit excellent surface appearance, flexibility, lightness, shape retention, shape shaping, reworkability and high light reflectivity. It is to provide a foam sheet having fine pores necessary for the above. At the same time, this provision is realized without using particularly prominent manufacturing equipment. That is, it is realized by using relatively inexpensive melt extrusion equipment without increasing production costs.

  As a result of diligent research to solve the above problems, the present inventors have found that a polyester foam comprising a polyester resin composition in which a specific amount of a foam nucleating agent and a thickening agent are blended with a crystalline polyester has a melt retention in a specific range. When the foam has a stability and a bubble diameter, the foam size of the foam is uniformly refined from the skin layer to the inside of the sheet, and a highly foamed sheet with high optical reflectance, excellent surface appearance, shape retention and reworkability The present invention has been found and the present invention has been completed.

That is, the present invention
1． (A) It consists of a polyester resin composition containing 60 to 99.8% by weight of a crystalline polyester resin, (B) 0.1 to 20% by weight of a foam nucleating agent, and (C) 0.1 to 20% by weight of a thickener. A polyester resin composition foamed sheet, wherein the foamed sheet satisfies the following (1) to (2).
(1): Melt retention stability under the melting point + 45 ° C. condition of the foamed sheet is 2% or less (2): Average cell diameter in a direction perpendicular to the take-up direction of the foamed sheet: 0.1 to 50 μm
2. Apparent density of ^{0.4g / cm 3 ~0.9g / cm 3} , the 1. The polyester resin composition foam sheet according to 1.
3. 1. The average light reflectance at a wavelength of 400 nm to 700 nm is 85% or more. Or 2. The polyester resin composition foam sheet according to 1.

4). 1. The tensile elasticity modulus in the direction perpendicular to the take-up direction of the polyester resin composition foam sheet is 400 MPa or more. ~ 3. The thermoplastic polyester resin composition foam sheet according to any one of the above.
5. The melt viscosity of the polyester resin composition foamed sheet at a melting point of + 15 ° C. and a shear rate of 1000 sec ⁻¹ is 250 Pa.s. s or more, 700 Pa. s or less, the above 1. ~ 4. The thermoplastic polyester resin composition foam sheet according to any one of the above.
6). The polyester resin composition foam sheet has a sheet thickness of 0.5 to 2 mm. ~ 5. The polyester resin composition foam sheet according to any one of the above.
7). (B) The foam nucleating agent is polytetrafluoroethylene, and the component (B) is contained in the thermoplastic polyester resin composition in an amount of 2 to 10% by weight. ~ 6. The polyester resin composition foam sheet according to any one of the above.

8). (C) The thickener is one or more selected from a compound having an epoxy group, a compound having an oxazoline group, and a carbodiimide. ~ 7. The polyester resin composition foam sheet according to any one of the above.
9. (C) The above-mentioned 8. wherein the thickener is a styrene copolymer having an epoxy value. The polyester resin composition foam sheet according to 1.
10. (A) The crystalline polyester is polytrimethylene terephthalate as described in the above item 1. ~ 9. The thermoplastic polyester resin composition foam sheet according to any one of the above.
11. Above 1. -10. The polyester resin composition described in any of the above is melted in an extruder, and (C) 0.01% to 0.6% by weight of inorganic gas is injected into the melt at the melting temperature to mix and dissolve. After that, it is extruded from a die at an extrusion pressure of 10 MPa to 100 MPa, foamed and molded, and immediately cooled and solidified. -10. The polyester resin composition foam sheet according to any one of the above.

12 Above 1. -10. 0 to 99.9 parts by weight of the polyester resin composition described in any of the above and 100 to 0.1 parts by weight of the polyester resin composition foam sheet extruded from the die 2 by the method described in 11 above are melted in an extruder. (C) 0.01% to 0.6% by weight of inorganic gas is injected into the melt at the melting temperature, mixed and dissolved, and then extruded from the die at an extrusion pressure of 10 to 100 MPa. The above-mentioned 11. obtained by foam-molding and promptly cooling and solidifying. The polyester resin composition foam sheet according to 1.
13. (C) The gas species of the inorganic gas is nitrogen, the above 11. Or 12. The thermoplastic polyester resin composition foam sheet according to 1.
14 Above 1. ~ 13. An optical reflector comprising the thermoplastic polyester resin composition foamed sheet according to any one of the above.
It is.

  The polyester resin composition foam sheet according to the present invention has excellent surface appearance, lightness, shape shaping, reworkability, and light reflectivity. For this reason, it is useful for various uses such as food containers, packaging materials, building materials, and optical reflectors.

The present invention will be specifically described below.
The polyester resin composition foam sheet of the present invention comprises (A) 60 to 99.8% by weight of crystalline polyester, (B) 0.1 to 20% by weight of a foam nucleating agent, and (C) a thickener 0.1 to 20%. It consists of a polyester resin composition containing% by weight.
(A) Although it does not restrict | limit especially as a kind of crystalline polyester, From a heat resistant, optical reflectivity, and a shape shaping property viewpoint, a polyethylene terephthalate, a polytrimethylene terephthalate, a polyethylene naphthalate, a poly trimethylene na Polyester resins such as phthalate, polycyclohexanedimethyl terephthalate, polycyclohexanedimethyl naphthalate and polylactic acid, and copolymers thereof are preferably used. In this case also, other thermoplastic resins can be blended and used in the form of a blend composition.

In the present invention, among crystalline polyesters, polytrimethylene terephthalate and a copolymer thereof are more preferable from the viewpoints of optical reflectivity and shape shaping. This is because, firstly, an appropriate crystallization rate inherent to the PTT resin, secondly, chemical stability derived from the molecular structure of the PTT resin, which is a kind of saturated polyester with low chemical reactivity, It is thought to be derived from the flexibility of crystals that come from the zigzag molecular skeleton structure.
Here, polytrimethylene terephthalate (hereinafter abbreviated as PTT) is trimethylene terephthalate having terephthalic acid as an acid component and trimethylene glycol (also referred to as 1,3-propanediol, hereinafter abbreviated as “TMG”) as a diol component. Indicates a polyester composed of repeating units.

The PTT resin can be obtained by a conventionally known method. For example, PTT resin is made from dimethyl terephthalate and trimethylene glycol, and other copolymerization components as necessary, and transesterified at a normal pressure of 180 ° C to 260 ° C using titanium tetrabutoxide as a catalyst. After the reaction, it can be obtained by performing a polycondensation reaction at 220 ° C. to 270 ° C. under reduced pressure.
In the case of this PTT resin, other thermoplastic resins can be blended and used in the form of a blend composition.

Examples of the copolymer component include ethylene glycol, 1,1-propanediol, 1,2-propanediol, 2,2-propanediol 1,2-butanediol, 1,3-butanediol, and 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 benzenesulfonic acid tetramethyl Ester-forming monomers such as phosphonium salts, isophthalic acid, oxalic acid, succinic acid, adipic acid, dodecanedioic acid, fumaric acid, maleic acid, 1,4-cyclohexanedicarboxylic acid, polyethylene glycol, polypropylene glycol, polytetramethylene glycol and the like These copolymers are exemplified.
In order to increase the thermal stability and the flexibility of the sheet, the light reflectivity, and the heat resistance when the sheet is produced, it is preferable that the content of the above random copolymer is 30 mol% or less, and 20 mol. % Or less, more preferably 10 mol% or less.

The degree of polymerization of the PTT resin of the present invention is preferably in the range of 0.5 dl / g to 4 dl / g with the intrinsic viscosity [η] as an index. By making the intrinsic viscosity 0.5 dl / g or more, it becomes easy to produce a sheet, and it becomes easy to make the bubble size fine, and a foam sheet and a molded body having excellent strength and flexibility, Easy to do. On the other hand, by setting it to 4.0 dl / g or less, it becomes easy to form a sheet. The intrinsic viscosity [η] is more preferably in the range of 0.7 dl / g to 3 dl / g, further preferably in the range of 0.9 dl / g to 2.5 dl / g, and in the range of 1.0 dl / g to 2 dl / g. Particularly preferred.

The PTT resin of the present invention preferably has a carboxyl end group concentration of 0 eq / ton to 80 eq / ton. By doing in this way, it becomes easy to improve the weather resistance of a sheet | seat and a molded object, chemical resistance, hydrolysis resistance, and heat resistance. The carboxyl end group concentration is more preferably 0 eq / ton to 50 eq / ton or less, further preferably 0 eq / ton to 30 eq / ton or less, particularly preferably 0 meq / kg to 20 meq / kg, and the lower the better.
For the same reason, a bis (3-hydroxypropyl) ether component (structural formula: -OCH2CH2CH2OCH2CH2CH2O-, hereinafter "BPE"), which is a glycol dimer component in which TMG, which is a glycol component of the PTT resin, is bonded via an ether bond. Is preferably 0 wt% to 2 wt%. The content is more preferably 0.1% by weight to 1.7% by weight, and still more preferably 0.15% by weight to 1.5% by weight.

The ratio of the crystalline polyester in the polyester resin composition of the present invention is 60.0 wt% to 99.8 wt%, and 75.0 wt% to 98.0 wt% from the viewpoint of the optical reflectance of the foamed sheet and the sheet appearance. It is more preferable that it is weight%, and it is still more preferable that it is 85.0 weight%-95.0 weight%.
The crystalline polyester in the polyester resin composition of the present invention includes cases where various organic substances, inorganic substances and various additives are included. Even in such a case, the ratio of the crystalline polyester needs to be in the above-described range.

The (B) foaming nucleating agent referred to in the present invention is not particularly limited as long as it is a substance that becomes a foaming nucleus of the crystalline polyester resin, but talc, mica, kaolin, alumina, calcium carbonate, layered silicate, barium sulfate, Powdered inorganic compounds such as apatite, and fluorine resins represented by polytetrafluoroethylene (hereinafter abbreviated as PTFE) are effective as a foam nucleating agent. Among them, PTFE, particularly low molecular weight PTFE is most effective as a foam nucleating agent. Low molecular weight PTFE means that the melt viscosity obtained by measurement using a flow tester method at 340 ° C. is 2500 Pa.s. s or less, PTFE having a number average molecular weight of several thousand to several hundred thousand (60 × 10 ⁴ or less), preferably 5,000 to 600,000, more preferably 10,000 to 600,000, and low mechanical strength. Specifically, it is added to impart lubricity and water repellency to polymers and paints. The number average molecular weight of the PTFE is a value calculated from the melt viscosity obtained by measurement using the flow tester. Further, low molecular weight PTFE does not fibrillate when melt-kneaded with a polyester resin, and by using it as a foaming nucleating agent for the polyester resin, it is possible to obtain a foam having fine bubbles that has not been achieved so far.
These low molecular weight PTFE production methods include emulsion polymerization, suspension polymerization, telomerization of tetrafluoroethylene in a solvent, firing of low molecular weight PTFE, thermal decomposition of high molecular weight PTFE, or decomposition by radiation. Laws are known. Among them, the emulsion polymerization method and the decomposition method by radiation are the most preferable production methods from the viewpoint of the crystal nucleating agent.

The particle diameter of the low molecular weight PTFE in the polyester resin composition foamed sheet of the present invention is 0.05 to 1.0 μm in average particle diameter as measured with an electron microscope observation or dynamic light scattering method with respect to primary particles. It is preferable from the viewpoint of optical reflectivity of the foamed sheet, and most preferably 0.1 to 0.5 μm. Furthermore, with respect to secondary particles (aggregates of primary particles), the 50% by weight average particle diameter is preferably 0.5 to 30 μm, more preferably 2 to 20 μm, most preferably 3 to 10 μm, as measured by a light transmission method. preferable.
The content of low molecular weight PTFE in the resin composition of the present invention is preferably 0.1 to 20% by weight from the viewpoint of optical reflection characteristics and sheet appearance, more preferably 1 to 15% by weight. More preferably, it is -110 weight%, It is especially preferable that it is 3-7 weight%.

  The (C) thickener in the polyester resin composition of the present invention means that the (C) component is added to the (A) component and the (B) component, so that the melt residence stability of the polyester resin composition is 2% or less. Is not particularly limited as long as it is a compound to be controlled, for example, a compound having an epoxy group, a compound containing an acid anhydride, a compound having an oxazoline group, a compound containing an isocyanate group, a carbodiimide compound, and a non-fired compound. Molecular weight PTFE or the like is preferably used, and a compound having an epoxy group, a compound having an oxazoline group, and a carbodiimide compound are more preferably used, and particularly a polyfunctional epoxy compound is most preferably used. A polyfunctional epoxy compound refers to a compound having two or more epoxy groups (oxirane rings) in the molecule. Specifically, the so-called bisphenol A type epoxy resin, bisphenol S type epoxy resin, bisphenol F type epoxy resin, resorcin type epoxy resin, phenol novolac and linear high molecular weight cresol produced by the condensation reaction of bilphenol A and epichlorohydrin. Novolak type epoxy resin, aliphatic epoxy resin, alicyclic epoxy resin, polyglycidylamine type epoxy, epoxy group-containing styrene copolymer, epoxy group-containing polyester copolymer, etc. It is done. Among these, an epoxy group-containing styrene copolymer is most preferably used.

The styrene copolymer can be obtained by copolymerizing a vinyl monomer having an epoxy group and styrene. As the vinyl monomer having an epoxy group, glycidyl (meth) acrylate, (meth) acrylic acid ester having a cyclohexene oxide structure, (meth) allyl glycidyl ether, or the like can be used. Preferred is glycidyl (meth) acrylate.
The styrene copolymer having an epoxy group may be used in combination with any other vinyl monomer other than styrene that does not have any epoxy group as long as the effects of the present invention are not impaired.
Other vinyl monomers include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (meth ) (Meth) acrylic acid alkyl ester, (meth) acrylic acid polyalkylene glycol ester, (meth) having an alkyl group having 1 to 22 carbon atoms such as cyclohexyl acrylate (the alkyl group may be linear or branched) Alkoxyalkyl esters of acrylic acid, hydroxyalkyl esters of (meth) acrylic acid, dialkylaminoalkyl esters of (meth) acrylic acid, benzyl esters of (meth) acrylic acid, phenoxyalkyl esters of (meth) acrylic acid, isobornyl (meth) acrylate Esters, (meth) acrylic acid al Silyl alkyl ester and the like. Other examples include maleic anhydride, fumaric acid, (meth) acrylamide, (meth) acrylic dialkylamide, vinyl esters such as vinyl acetate, vinyl ethers, (meth) allyl ethers, aromatic vinyl such as styrene and α-methylstyrene. An α-olefin monomer such as a monomer, ethylene, or propylene can be used. These can use 1 type, or 2 or more types.

From the viewpoint of MFR of the resin composition, the epoxy value of the styrene copolymer needs to be 0.1 to 10 meq / g, more preferably 0.5 to 5 meq / g. Most preferably, it is 0-3 meq / g.
The weight average molecular weight of the styrene copolymer is preferably 500 to 50,000, more preferably 1000 to 30000, and more preferably 2000 to 20000 from the viewpoint of the melt residence stability of the resin composition. Most preferred.
Furthermore, the glass transition temperature of the styrene copolymer is preferably 20 ° C. or higher, more preferably 40 ° C. or higher, from the viewpoint of MD (mold deposit) when molding the resin composition.

In the styrene copolymer having an epoxy group, the proportion of styrene units is 10 to 90% by mass, the proportion of vinyl monomer units having an epoxy group is 5 to 70% by mass, and the proportion of other vinyl monomer units is 0. It is preferable that it is -85 mass%. More preferably, the proportion of styrene units is 30 to 80% by mass, the proportion of vinyl monomer units having an epoxy group is 10 to 50% by mass, and the proportion of other vinyl monomer units is 0 to 60% by mass. .
The styrene copolymer having an epoxy group can be prepared by a normal radical polymerization method using a continuous tube process or a continuous stirred tank process in solution polymerization, emulsion polymerization, bulk polymerization, dispersion polymerization, or suspension polymerization.

Moreover, it is preferable to mix | blend 0.1-20 weight part of the ratio of the (C) thickener in this invention resin composition from a viewpoint of the optical reflection characteristic of this foam sheet and a sheet | seat external appearance, 0.3-5 More preferably, it is blended in an amount of 0.5 to 3 parts by weight.
Other inorganic substances that can be incorporated into the resin composition include glass fiber, carbon fiber, talc, mica, wollastonite, kaolin clay, calcium carbonate, titanium dioxide, silica dioxide, and other inorganic fillers, inorganic lubricants, and polymerization. A catalyst residue etc. are mentioned.
Further, additives that can be blended in the resin composition include organic and inorganic dyes and pigments, matting agents, heat stabilizers, flame retardants, antistatic agents, antifoaming agents, color adjusters, antioxidants, Examples include ultraviolet absorbers, crystal nucleating agents, brighteners, impurity scavengers, thickeners, and surface conditioners.

  The heat stabilizer that can be blended in the resin composition is preferably a pentavalent or / and trivalent phosphorus compound or a hindered phenol compound. The addition amount of the phosphorus compound is preferably 2 ppm to 500 ppm, more preferably 10 ppm to 200 ppm as a weight ratio of the phosphorus element to 100 parts by weight of the resin composition. As specific compounds, trimethyl phosphite, phosphoric acid, phosphorous acid, and tris (2,4-di-tert-butylphenyl) phosphite (Irgafos 168 manufactured by Ciba Specialty Chemicals Co., Ltd.) are preferable. .

Here, the hindered phenolic compound is a phenolic derivative having a substituent having a steric hindrance at a position adjacent to a phenolic 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 100 parts by weight of the resin composition. preferable.
Specific compounds include pentaerythritol-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (Irganox 1010 manufactured by Ciba Specialty Chemicals Co., Ltd.), 1, 1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate (Ciba Specialty) Chemicals Co., Ltd. Irganox 1076, etc.), N, N′-hexamethylenebis (3,5-tert-butyl-4-hydroxy-hydrocinnamamide), ethylenebis (oxyethylene) bis [3- (5- tert-butyl-4-hydroxy-m-tolyl) propionate] (Ciba Irganox 245 manufactured by Specialty Chemicals Co., Ltd.), N, N′hexane-1,6-diylbis [3- (3,5 di-tert-butyl-4-hydroxyphenylpropionamide) (Ciba Specialty Chemicals Co., Ltd. Irganox 1098 etc.) etc. are preferable. Of course, using these stabilizers in combination is one of the preferred methods.

In the present invention, it is also preferable to add a low molecular weight volatile impurity scavenger. 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, and more preferably 0.01% by weight to 0.2% by weight with respect to 100 parts by weight of the resin composition.
Specific compounds include polyamides such as nylon 6.6, nylon 6, and nylon 4.6, polymers such as polyethyleneimine, and a reaction product of N-phenylbenzeneamine and 2,4,4-trimethylpentene ( Irganox 5057 manufactured by Ciba Specialty Chemicals Co., Ltd.), N, N′hexane-1,6-diylbis [3- (3,5 di-tert-butyl-4-hydroxyphenylpropionamide) (Ciba Irganox 1098 manufactured by Specialty Chemicals Co., Ltd.), 2,6-di-tert-butyl-4- (4,6-bis (octylthio) -1,3,5-triazin-2-ylamino) phenol (Ciba)・ Irganox 565 manufactured by Specialty Chemicals Co., Ltd.) is preferable. Of course, a combination of these is also one of the preferred methods.

  The polyester resin composition foamed sheet of the present invention has a melt residence stability of 2% or less, more preferably 1% or less, and most preferably 0.5% or less. Further, the melt residence stability is preferably 0% or more. The melt residence stability is a polyester resin composition foam sheet having a water content of 100 ppm or less, an RMS800 type viscoelastic device manufactured by Rheometric Co., Ltd., a shear rate of 1 rad / sec, a melting point of the foam sheet. This is a value obtained by measuring the melt viscosity measured at + 45 ° C. every 30 seconds for 20 minutes and the rate of change per minute.

Further, in the polyester resin composition foam sheet of the present invention, the average cell diameter in the direction perpendicular to the take-up direction of the sheet needs to be 0.1 μm to 50 μm from the viewpoint of optical reflection performance, and is 0.5 μm to 30 μm. It is preferable that it is 1 micrometer-20 micrometers, it is more preferable that it is 2 micrometers-10 micrometers.
The average cell diameter in the direction perpendicular to the sheet take-up direction is preferably 1/10 or less of the sheet thickness, more preferably 1/50 or less, from the viewpoint of excellent flexibility and light reflectivity. It is preferably 1/100 or less.

The average bubble size in the direction perpendicular to the sheet take-off direction is obtained by using image analysis software from a cross-sectional image obtained by observing the cross section of the sheet using a scanning electron microscope (hereinafter abbreviated as “SEM (Scanning Electron Microscope)”). Calculated as equivalent circle diameter.
The thickness of the polyester resin composition foam sheet of the present invention is preferably 50 μm to 10 mm. When the thickness is 50 μm or more, handling of the sheet is facilitated, and when the thickness is 10 mm or less, heat forming (shaping) is facilitated. The thickness of the foam sheet is more preferably 100 μm to 5 mm, and still more preferably 200 μm to 3 mm. Furthermore, from a viewpoint of the self-holding property and heat shaping property of a foam sheet, it is particularly preferable that the thickness is 500 μm to 2 mm.

Polyester resin composition foamed sheet of the present invention, the apparent density ^is preferably ^{0.4g / cm 3 ~0.9g / cm 3} . By setting the apparent density to 0.4 g / cm ³ or more, it becomes possible to extrude the foamed sheet without breaking bubbles during sheeting, and by setting the apparent density to 0.9 g / cm ³ or less, the optical reflection of the foam sheet. The performance can be satisfied. Further, from the viewpoint of fine bubbles, it is more preferred apparent density of the foam sheet is ^{0.5g / cm 3 ~0.8g / cm 3} .

  In addition, the polyester resin composition foam sheet of the present invention requires that the average light reflectance of the polyester resin composition foam sheet at a wavelength of 450 nm to 700 nm be 85% or more, and more preferably 90% or more. 95% or more is most preferable. By setting it as such a reflectance, it comes to be suitable as an optical reflecting plate. Here, the light reflectance indicates a relative value when the reflectance of the barium sulfate white plate is 100%. The reflectance described here is a value measured using a spectrophotometer, and indicates the total reflectance including diffuse reflection and specular reflection.

  The polyester resin composition foam sheet of the present invention preferably has a tensile elastic modulus in the direction perpendicular to the sheet take-up direction of 400 MPa or more from the viewpoint of the self-holding property of the foam sheet, more preferably 600 MPa or more. Preferably, the pressure is 800 MPa or more. By blending the component (C) in the above range in the polyester resin composition constituting the polyester resin composition foamed sheet, the thickness unevenness of the sheet is reduced, and the tensile modulus in the direction perpendicular to the take-up direction of the sheet. Can be controlled to 400 MPa or more.

The polyester resin composition foamed sheet of the present invention has a melting viscosity of 250 Pa.s at a melting point of + 15 ° C. and a shear rate of 1000 sec ⁻¹ . s or more, 700 Pa. s or less is preferable from the viewpoint of refining the bubbles in the foam sheet, and is 300 Pa.s. s or more, 650 Pa. s or less, more preferably 350 Pa.s. s or more, 600 Pa. s or less, more preferably 400 Pa.s. s or more, 550 Pa. Most preferably, it is s or less. The melt viscosity is a numerical value measured using a twin capillary rheometer and subjected to Berkeley correction and Rabinovitch correction. It becomes possible to control melt viscosity by mix | blending (C) component in the said range in the polyester resin composition which comprises a polyester resin composition foam sheet.

Next, the manufacturing method of the polyester resin composition foam sheet which concerns on this invention is demonstrated.
The polyester resin composition foam sheet of the present invention comprises (A) a crystalline polyester resin 60 to 99.8% by weight, (B) a foam nucleating agent 0.1 to 20% by weight, and (C) a thickener 0.1 to A melt comprising 20% by weight of a polyester resin composition was injected with 0.01 to 0.6 part by weight of (C) inorganic gas with respect to 100 parts by weight of the polyester resin composition at the melting temperature of the melt. After mixing and dissolving, the product is obtained by a “special melt extrusion foaming method” in which it is extruded from a die at an extrusion pressure of 10 MPa to 100 MPa and foamed, and quickly cooled and solidified, and more preferably a twin screw extruder. (A) Polyester containing 60 to 99.8% by weight of crystalline polyester, (B) 0.1 to 20% by weight of foam nucleating agent, and (C) 0.1 to 20% by weight of thickener. Resin composition is uniaxial After supplying to the unloader and mixing and dissolving (C) 0.01 to 0.6 parts by weight of inorganic gas with respect to 100 parts by weight of the polyester resin composition at the melting temperature of the melt, 10 MPa It is obtained by a “special melt extrusion foaming method” which is extruded from a die at an extrusion pressure of ˜100 MPa and foam-molded and quickly cooled and solidified, and most preferably, 0 to 99.9 parts by weight of the polyester resin composition 100 to 0.1 parts by weight of a polyester resin composition foamed sheet once extruded by the special melt extrusion foaming method is melted in an extruder, and (C) inorganic gas is added to the melt at the melting temperature. .01 wt% to 0.6 wt% injected, mixed and dissolved, then extruded from the die at an extrusion pressure of 10 MPa to 100 MPa, foamed, and immediately cooled and solidified Obtained by the method.
By reusing a polyester resin composition foam sheet that has been extruded once, the foam sheet becomes finer and a polyester resin composition foam sheet with a better appearance can be obtained. In addition, waste materials can be recycled, greatly reducing costs. The

Additives necessary for producing a polyester resin composition foamed sheet can be added by a method of adding at the time of polymerization, a method of adding by kneading after polymerization, or a method of combining these, etc. It can be appropriately selected depending on the type and amount of the object, the required performance, and the like.
As an extrusion condition of the biaxial extruder, from the viewpoint of refining the bubbles of the polyester resin composition foamed sheet, a component containing (A) a crystalline polyester, (B) a foam nucleating agent, and (C) a thickener. The resin composition temperature at the cylinder outlet of the twin screw extruder is preferably controlled to its melting point + 85 ° C. or lower, more preferably controlled to the melting point + 75 ° C. or lower, and most preferably controlled to the melting point + 65 ° C. or lower.
As the extrusion conditions of the single-screw extruder, it is desirable to set the temperature so that no unmelted material remains in the extruder and the thermal decomposition of the resin composition can be suppressed. It is preferable to set it as 30 degreeC, It is more preferable to set it as melting | fusing point +0 degreeC-20 degreeC, It is still more preferable to set it as melting | fusing point +0 degreeC-15 degreeC.

  If necessary, install a filter between the extruder and the base to remove foreign substances, install a gear pump to increase the quantitative supply, and improve the dispersibility of the injected substance A static mixer can be installed, or a heat exchange unit can be installed to keep the temperature constant. In such a case, it is desirable to appropriately select the pressure and temperature so that the substance injected in the vicinity of the equipment does not become large bubbles. Even when these devices are installed, it is desirable to set the temperature so that unmelted material does not remain and the thermal decomposition of the composition can be suppressed, and it is set to approximately the melting point of the polyester resin composition + 0 ° C. to 30 ° C. preferable.

The polyester resin composition foam sheet of the present invention can obtain a fine foam sheet only by injecting a specific amount of (C) an inorganic gas into the melted polyester resin composition and extrusion-molding it. Specific examples include inert compounds such as hydrogen, oxygen, nitrogen, carbon dioxide, helium, argon, xenon and water. Among these, nitrogen is particularly preferably used from the viewpoint of forming fine pores in the sheet.
(C) The amount of inorganic gas injected is 0.01 parts by weight to 0.6 parts by weight with respect to 100 parts by weight of the polyester resin composition from the viewpoints of making the bubbles finer and improving the surface state of the sheet. It is preferably part by weight, more preferably 0.02 part by weight to 0.4 part by weight, and most preferably 0.05 part by weight to 0.2 part by weight.
Any method may be used as long as it is between the extruder and the die. However, it is preferable to inject with the extruder because (C) the inorganic gas can be uniformly injected into the melt.

The melt is then extruded from the die and formed into a sheet-like shape, and the pressure is released and the molten material is foamed. The die can be appropriately selected depending on the shape of the target sheet, but in order to obtain a sheet having a uniform thickness, a linear slit called T-die or I-die or a circular shape called round die is used. It is desirable to use a slit. It is desirable that the structure of the base is appropriately designed so that bubbles do not break in the base. Furthermore, from the viewpoint of reducing the pore size of the foam sheet, the pressure of the melt at the inlet of the die is preferably 10 MPa or more, more preferably 13 MPa or more, and most preferably 15 MPa or more. . Although there is no upper limit in particular, it is good to set it as the extrusion pressure of 100 Mpa or less considering the structure of an installation.
It is desirable to set the die temperature at the time of extrusion low as long as the melt does not solidify. Specifically, the melting point of the composition is preferably + 0 ° C. to 30 ° C., and the melting point + 0 ° C. to 20 ° C. More preferably, the melting point is set to + 0 ° C. to 15 ° C., and it is preferable to set the melting point as low as possible within a range where the melt can be uniformly extruded.

  In the special melt extrusion foaming method, the foamed and molded melt is then cooled and solidified, but in the present invention, it is cooled and solidified immediately so as to suppress the enlargement of bubbles. Here, promptly refers to cooling so as to have the above-described thermal characteristics of the sheet, and specifically, the time for cooling the sheet below the glass transition temperature of the resin composition after being extruded from the die is 30. It is preferably within seconds, more preferably within 10 seconds, and particularly preferably within 5 seconds. When obtaining an amorphous sheet, it is particularly important to cool and solidify immediately.

Examples of a method for achieving such cooling and solidification include a method in which a melt is brought into contact with a solid such as a cooling roll or a cooling belt, a method in which a sheet is brought into contact with a liquid such as water, and a method in which these are combined. . Of these, a method in which a melt extruded from a slit-shaped die is cast (arranged) on a roll or a belt, and then put into water and immediately cooled and solidified is most preferable.
In addition, 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., further preferably 0 ° C. to 30 ° C., and particularly preferably 0 ° C. to 20 ° C. The time from the extrusion from the die to the contact with the solid or liquid is preferably 0.1 seconds to 10 seconds, more preferably 0.1 seconds to 5 seconds, and 0.1 seconds to 2 seconds. It is particularly preferable to do this.

Among the polyester resin composition foamed sheets of the present invention, an amorphous one can be formed into a shaped foamed molded article by thermoforming.
The shape of the molded body can be appropriately selected according to the application. For example, box shape, cup shape, corrugated plate shape, etc. are 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, pressure forming, and vacuum press forming. Molding and vacuum press molding are more preferable.
Moreover, the polyester resin composition foam sheet of the present invention exhibits an effect of improving luminance and eliminating luminance unevenness, for example, as an optical reflector for a large-sized liquid crystal television by the thermoforming. Furthermore, as the reflector increases in size, the reflector sheet is required to have self-supporting and dimensional stability. However, it is possible to shape the rib structure, boss structure, etc. by heat shaping, and the rigidity and dimensional accuracy of the molded body. And the number of parts can be reduced.

The effects of the present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples. The (A) crystalline polyester and (B) foam nucleating agent used are as follows.
(A) Crystalline polyester A1: Polytrimethylene terephthalate (PTT); Cortera CP513000-0312RC
Intrinsic viscosity [η] = 1.30 (dl / g)
The intrinsic viscosity [η] of PTT was extrapolated from the Ostwald viscometer using a Ostwald viscometer, the ratio ηsp / C of specific viscosity ηsp and concentration C (g / 100 ml) in o-chlorophenol to a concentration of zero, It calculated | required with the following formula | equation.
[Η] = lim (ηsp / C) C → 0
A2: Polyethylene terephthalate (PET); NEH2050 (manufactured by Unitika)

(B) Foam nucleating agent B1: PTFE (polytetrafluoroethylene); Lubron L-5 (manufactured by Daikin Industries)
(C) Thickener ・ C1: Epoxy-modified styrene acrylic copolymer; ARUFON UG4040 (manufactured by Toagosei Co., Ltd.)
C2: Epoxy-modified styrene acrylic copolymer; ARUFON UG4000 (manufactured by Toagosei Co., Ltd.)
C3: Carbodiimide; Carbodilite LA-1 (Nisshinbo Co., Ltd.)
C4: 1,3-phenylenebisoxazoline (Mikuni Pharmaceutical Co., Ltd.)
・ C5: Denacol EX203 (manufactured by Nagase ChemteX Corporation)

The main measured values in the following examples were measured by the following methods.
(1) Melt residence stability of polyester resin composition foamed sheet (A) When PTT is used as the component, the polyester resin composition foamed sheets obtained in Examples and Comparative Examples are prepared at 120 ° C. for 5 hours. After drying with a dehumidifying dryer, a melt viscosity was measured every 30 seconds under a nitrogen stream using a rheometric RMS800 viscoelasticity device at a shear rate of 1 rad / sec, 270 ° C. for 20 minutes, 1 The rate of change per minute was defined as melt residence stability.
When PET is used as the component (A), the polyester resin composition foam sheet obtained in the example is dried at 150 ° C. for 4 hours with a dehumidifying dryer, and then the rheometric RMS800 type viscosity is used. Using an elastic device, the melt viscosity was measured every 30 seconds at a shear rate of 1 rad / sec, 295 ° C. for 20 minutes under a nitrogen stream, and the rate of change per minute was defined as the melt residence stability.

(2) Melt Viscosity of Polyester Resin Composition Foamed Sheet Polyester resin composition foamed sheet was subjected to conditions of resin temperature: 240 ° C. (in the case of PTT) and 265 ° C. (in the case of PET) using a ROSAND twin capillary rheometer. The melt viscosity of 1000 sec ⁻¹ was measured. The melt viscosity data used were subjected to Berkeley correction and Rabinovitch correction.
(3) Sheet thickness The thickness of the polyester resin composition foam sheet was measured with a thickness meter at intervals of 100 mm in the width direction, and the average value was obtained.
(4) Apparent density The polyester resin composition foamed sheet was dried at 50 ° C. and obtained by dividing the weight when the constant weight value was reached by the volume. The volume was determined by immersing the sheet in water.

(5) Bubble diameter <Skin layer>
The skin layer cell diameter of the polyester resin composition foam sheet was cut using a diamond cutter in a direction perpendicular to the sheet take-up direction, and the cross section was observed using a scanning electron microscope (SEM). The bubble diameter of the cross-sectional image (surface layer 200 μm × 200 μm range) was determined as an average value of values calculated as equivalent circle diameters using image analysis software. As an image analysis software, image-Pro Plus ver. 4.0 was used.
When the bubble diameter exceeded 200 μm, measurement was impossible.

<Inside>
The internal cell diameter of the polyester resin composition foamed sheet is a cross section obtained by cutting the sheet in a direction perpendicular to the sheet take-up direction using a diamond cutter and observing the cross section using a scanning electron microscope (SEM). The bubble diameter of the image (in the range of 200 μm × 200 μm in the center) was obtained as an average value of values calculated as equivalent circle diameters using image analysis software. As an image analysis software, image-Pro Plus ver. 4.0 was used.
When the bubble diameter exceeded 200 μm, measurement was impossible.

<Average bubble diameter>
The average cell diameter of the polyester resin composition foam sheet is a cross section obtained by observing the cross section of the foamed sheet using a scanning electron microscope (SEM) by cutting the sheet in a direction perpendicular to the sheet take-up direction using a diamond cutter. The bubble diameter of the image (1000 μm × 1000 μm region from the surface layer to the inside) was obtained as an average value of values calculated as equivalent circle diameters using image analysis software. As an image analysis software, image-Pro Plus ver. 4.0 was used.

(6) Thickness unevenness The thickness of the polyester resin composition foam sheet is measured with a thickness meter at intervals of 100 mm in the width direction, the average value is obtained, and the difference between the maximum thickness and the average thickness at each measurement site, or the minimum When the difference between the thickness and the average thickness was 0.2 mm or more, ×, 0.1 or more, Δ when less than 0.2 mm, and ◯ when less than 0.1 mm.
(7) Average light reflectance Using the UV-2200 manufactured by Shimadzu Corporation, the total reflectance of the foamed sheet (specular reflectance + diffuse reflectance in a wavelength range of 450 nm to 700 nm in a method in which the incident angle is shifted by 8 °. ) Was measured every 10 nm, and the average total reflectance in the wavelength region was calculated. The average total reflectance was measured at 10 mm intervals in the sheet width direction, and the average value was obtained as the average light reflectance. In this case, the light reflectance is a relative value when the reflectance of the barium sulfate white plate is 100%.

(8) Tensile modulus (direction perpendicular to the sheet take-up direction) (TD direction)
A test piece was cut out in a direction perpendicular to the sheet take-up direction of the polyester resin composition foam sheet, and the tensile modulus was determined according to JIS K6767.
(9) Formability Using the polyester resin composition foam sheet, vacuum forming was performed with the vacuum forming mold shown in FIG.
Detailed conditions are described in the examples.

[Example 1]
Average particle diameter of primary particles 0.2 μm, average particle diameter of secondary particles 5 μm with respect to 93.7 parts by weight of PTT resin (manufactured by SHELL, CP513000-0312RC) having an intrinsic viscosity [η] of 1.30 dl / g PTFE (Daikin Kogyo Co., Ltd., Lubron L-5) 5.0 parts by weight, Thickener (Toagosei Co., Ltd., ARUFON UG4040) 1.0 parts by weight, Ciba Specialty Chemicals Co., Ltd. as a heat stabilizer Irgafos 168, Irganox 245, and Irganox 1098 made by dry blending each 0.1 parts by weight tumbler, using a ZSK-25 twin screw extruder with a screw speed of 300 rpm, a discharge rate of 15 kg / hour, and a resin temperature at the die outlet of 290 ° C. Extrusion was performed to obtain a PTT resin composition having a melting point of 225 ° C. The PTT resin composition was supplied to a 90 mmφ single screw extruder set at 235 ° C., melted, and then passed through a flow path heated to the same temperature as the extruder to form a T die having a width of 1000 mm and an interval of 0.6 mm. The sheet was extruded at a linear speed of 10 m / min to form a sheet.

At this time, 0.1% by weight of nitrogen gas with respect to the composition was injected from the middle of the extruder to be mixed and dissolved with the melt. Moreover, the pressure of the melt at the T die entrance was 19.7 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 the cooling water were controlled to be 10 ° C., and the time from the extrusion of the melt to the contact with the rotating roll was 0.6 seconds.
The obtained PTT resin composition foamed sheet had a thickness of 1.0 mm and a width of 960 mm, and the surface appearance was good. Further, the foam sheet was excellent in an apparent density of 0.65 g / cm ³ , an average bubble diameter of 8 μm, and a light reflectance of 94%.

[Example 2]
Average particle diameter of primary particles 0.2 μm, average particle diameter of secondary particles 5 μm with respect to 93.7 parts by weight of PTT resin (manufactured by SHELL, CP513000-0312RC) having an intrinsic viscosity [η] of 1.30 dl / g PTFE (Daikin Kogyo Co., Ltd., Lubron L-5) 5.0 parts by weight, Thickener (Toagosei Co., Ltd., ARUFON UG4040) 1.0 parts by weight, Ciba Specialty Chemicals Co., Ltd. as a heat stabilizer Irgafos 168, Irganox 245, and Irganox 1098 made by dry blending each 0.1 parts by weight tumbler, using a ZSK-25 twin screw extruder with a screw speed of 300 rpm, a discharge rate of 15 kg / hour, and a resin temperature at the die outlet of 290 ° C. Extrusion was performed to obtain a PTT resin composition having a melting point of 225 ° C. The PTT resin composition was supplied to a 90 mmφ single screw extruder set at 235 ° C., melted, and then passed through a flow path heated to the same temperature as the extruder to form a T die having a width of 1000 mm and an interval of 0.6 mm. The sheet was extruded at a linear speed of 10 m / min to form a sheet.
At this time, 0.1% by weight of nitrogen gas with respect to the composition was injected from the middle of the extruder to be mixed and dissolved with the melt. Moreover, the pressure of the melt at the T die entrance was 19.7 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 the cooling water were controlled to be 10 ° C., and the time from the extrusion of the melt to the contact with the rotating roll was 0.6 seconds.

Next, the obtained foamed sheet is pulverized with a pulverizer, and melted and kneaded with the twin-screw extruder, and 100 parts by weight of the PTT resin composition is used. After dry blending, the blended product was supplied to a 90 mmφ single screw extruder set at 235 ° C. and melted, and then passed through a flow path heated to the same temperature as the extruder, with a base of 1000 mm and an interval of 0.6 mm. The sheet was extruded from a T die at a linear speed of 10 m / min and formed into a sheet shape.
At this time, 0.1% by weight of nitrogen gas with respect to the resin composition was injected from the middle of the extruder to be mixed and dissolved with the melt. The pressure of the melt at the T die entrance was 19.2 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 the cooling water were controlled to be 10 ° C., and the time from the extrusion of the melt to the contact with the rotating roll was 0.6 seconds.

The obtained PTT resin composition foamed sheet had a thickness of 1.0 mm and a width of 960 mm, and the surface appearance was good. The foam sheet has a melt residence stability and a melt viscosity of 0.1% and 410 Pa., Respectively. It was a foam sheet with an apparent density of 0.63 g / cm ³ , an average bubble diameter of 6 μm, and a light reflectance of 96%.
The obtained PTT resin composition foam sheet was molded by a vacuum / pressure forming method to obtain a molded product forming a reflector having a length of 630 mm, a width of 400 mm, and a depth of 25 mm. For forming, first, the sheet was heated to 55 ° C. with heater radiation, and then contacted with an aluminum mold heated to 120 ° C. (see FIG. 1) at a degree of vacuum of 720 mmH and a pressure of 0.3 MPa. The crystallization was carried out by holding and crystallizing for 20 seconds. The obtained molded product was not torn and the mold shape was reproduced. Further, the obtained molded product was left in a drier at 120 ° C. for 48 hours, and the thermal shrinkage rate in the direction perpendicular to the sheet take-up direction and the sheet take-off direction was measured. Met. Further, warp deformation or the like of the molded product was not recognized. The results are shown in Table 1 below.

[Examples 3 to 4]
As shown in Table 1 below, a PTT resin composition foamed sheet was obtained in the same manner as in Example 2 except that the blending amount of the thickener was changed. The results are shown in Table 1 below. The thickness unevenness of the foamed sheet was small, and a fine foamed sheet having excellent lightness and surface appearance could be obtained within the scope of the present invention. (Note that the T-die pressure was also changed appropriately as shown in Table 1 according to the change in conditions. The same applies hereinafter.)

[Example 5]
A PTT resin composition foamed sheet was obtained in the same manner as in Example 2 except that the amount of nitrogen gas was changed as shown in Table 1 below. The results are shown in Table 1 below. The foamed sheet was a PTT resin composition foamed sheet having small thickness unevenness and having excellent lightness and surface appearance within the scope of the present invention.
[Examples 6 to 9]
As shown in Table 1 below, a PTT resin composition foamed sheet was obtained in the same manner as in Example 2 except that the type of thickener was changed. The results are shown in Table 1 below. In any case, the thickness variation of the foam sheet was small, and the PTT resin composition foam sheet had excellent lightness and surface appearance within the scope of the present invention.

[Example 10]
As shown in Table 1 below, a PTT resin composition foamed sheet was obtained in the same manner as in Example 2 except that the kind of inorganic gas was changed. The results are shown in Table 1 below. The foamed sheet was a PTT resin composition foamed sheet having small thickness unevenness and having excellent lightness and surface appearance within the scope of the present invention.
[Example 11]
As shown in Table 1 below, a polyester resin composition foamed sheet was obtained in the same manner as in Example 2 except that the kind of crystalline polyester was changed. The results are shown in Table 1 below. The thickness of the foamed sheet was small, and it was a polyester resin composition foamed sheet having excellent lightness and surface appearance within the scope of the present invention.

[Comparative Example 1]
A PTT composition foamed sheet was obtained in the same manner as in Example 2 except that the thickener used in Example 2 was not used in Comparative Example 1. The results are shown in Table 1 below. The obtained sheet had a small tensile elastic modulus in the TD direction, and the foam sheet had a large thickness unevenness and did not satisfy the required properties of the present application.
[Comparative Example 2]
A PTT resin composition foamed sheet was obtained in the same manner as in Example 2 except that the amount of nitrogen gas was changed as shown in Table 1 below. The results are shown in Table 1 below. The obtained sheet had a large apparent density and large thickness unevenness of the foamed sheet, and the sheet was broken and broken, and the required properties of the present application were not satisfied.

[Comparative Example 3]
As shown in Table 1 below, a PTT resin composition foamed sheet was obtained in the same manner as in Example 2 except that the kind of inorganic gas was changed. The results are shown in Table 1 below. The obtained sheet had a low apparent density, a large average bubble diameter, a low tensile elastic modulus in the TD direction, and a light reflectance that was not satisfactory.
[Comparative Examples 4 and 5]
A PTT composition foamed sheet was obtained in the same manner as in Example 2 except that the blending amount of the thickener in Example 2 was changed. The results are shown in Table 1 below. In Comparative Example 4, the melt retention stability is poor, and as a result, the melt viscosity is low. The resulting sheet has a low tensile elastic modulus in the TD direction and a large thickness unevenness of the foamed sheet, which does not satisfy the required characteristics of the present application. There wasn't. On the other hand, in Comparative Example 5, the melt residence stability was poor, and as a result, the melt viscosity was abnormally high, and the obtained sheet was unsatisfactory because of its high apparent density and low light reflectance.

  The polyester resin composition foam sheet of the present invention has excellent surface appearance, heat insulation, light weight, reworkability, 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 an optical reflector.

It is a figure which shows a vacuum forming metal mold | die.

Claims (14)

(A) It consists of a polyester resin composition containing 60 to 99.8% by weight of a crystalline polyester resin, (B) 0.1 to 20% by weight of a foam nucleating agent, and (C) 0.1 to 20% by weight of a thickener. A polyester resin composition foamed sheet, wherein the foamed sheet satisfies the following (1) to (2).
(1): Melt retention stability under the melting point + 45 ° C. condition of the foamed sheet is 2% or less (2): Average cell diameter in a direction perpendicular to the take-up direction of the foamed sheet: 0.1 to 50 μm Apparent density of ^{0.4g / cm 3 ~0.9g / cm 3} , the polyester resin composition foamed sheet according to claim 1.   The polyester resin composition foam sheet according to claim 1 or 2, wherein an average light reflectance at a wavelength of 400 nm to 700 nm is 85% or more.   The thermoplastic polyester resin composition foam sheet according to any one of claims 1 to 3, wherein a tensile elastic modulus in a direction perpendicular to the take-up direction of the polyester resin composition foam sheet is 400 MPa or more. The melt viscosity of the polyester resin composition foamed sheet at a melting point of + 15 ° C. and a shear rate of 1000 sec ⁻¹ is 250 Pa.s. s or more, 700 Pa. The thermoplastic polyester resin composition foam sheet according to any one of claims 1 to 4, which is s or less.   The polyester resin composition foam sheet according to any one of claims 1 to 5, wherein the sheet thickness of the polyester resin composition foam sheet is 0.5 to 2 mm.   The foam nucleating agent (B) is polytetrafluoroethylene, and the component (B) is contained in the thermoplastic polyester resin composition in an amount of 2 to 10% by weight. Polyester resin composition foam sheet.   (C) The polyester resin composition foam sheet according to any one of claims 1 to 7, wherein the thickener is at least one selected from a compound having an epoxy group, a compound having an oxazoline group, and a carbodiimide.   (C) The polyester resin composition foam sheet according to claim 8, wherein the thickener is a styrene copolymer having an epoxy value.   (A) The thermoplastic polyester resin composition foam sheet according to any one of claims 1 to 9, wherein the crystalline polyester is polytrimethylene terephthalate.   The polyester resin composition according to any one of claims 1 to 10 is melted in an extruder, and 0.01 wt% to 0.6 wt% of (C) inorganic gas is injected into the melt at the melting temperature. The polyester resin according to any one of claims 1 to 10, which is obtained by mixing and dissolving and extruding from a die at an extrusion pressure of 10 MPa to 100 MPa to perform foam molding, and quickly solidify by cooling. Composition foam sheet. The polyester resin composition 0 to 99.9 parts by weight according to any one of claims 1 to 10, and the polyester resin composition foam sheet 100 to 0.1 parts by weight extruded from the die 2 by the method according to claim 11. Is melted in an extruder, and at the melting temperature, (C) 0.01% to 0.6% by weight of inorganic gas is injected, mixed and dissolved, and then the extrusion pressure is 10 MPa to 100 MPa. The polyester resin composition foamed sheet according to claim 11, which is obtained by extruding from a die and foam-molding and quickly cooling and solidifying.   (C) The thermoplastic polyester resin composition foam sheet according to claim 11 or 12, wherein the gas type of the inorganic gas is nitrogen.   The optical reflecting plate which consists of a thermoplastic polyester resin composition foam sheet of any one of Claims 1-13.

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