JP5444617B2 - Method for producing foam molded body - Google Patents

Description

  The present invention relates to a resin composition for a foam molded article and a foam molded article obtained using the resin composition.

  Thermoplastic polyester resin foams are excellent in heat resistance and mechanical properties, and so far have been used as heat insulating materials, heat insulating materials, impact resistant materials, and the like (see, for example, Patent Document 1 or 2). Moreover, since it is excellent also in light diffusibility and a reflectance, it has been used also as a reflecting plate of backlights, such as a lighting fixture and a display (for example, refer patent document 3).

In particular, as a thermoplastic polyester resin foam used as a reflector, a polyethylene terephthalate (PET) film prepared using germanium as a polycondensation catalyst is impregnated with a non-reactive gas and then foamed. Have been used favorably. However, since germanium, which is a polycondensation catalyst, is expensive, there is a problem that the manufacturing cost of the resulting resin foam (reflecting plate) is increased.
Japanese Patent Laid-Open No. 5-230259 Japanese Patent No. 3138488 JP 2006-335935 A

  In order to keep the manufacturing cost of the resin foam (reflecting plate) low, it is preferable to use antimony instead of germanium as a polycondensation catalyst for PET. However, although the reason is not clear, in the embodiment using antimony, it is easy to crystallize when impregnating a PET film with a non-reactive gas, and it is obtained from a PET film impregnated with a non-reactive gas. There was a problem that the diffuse reflectance of the obtained foam was inferior to that of a PET film (foam) obtained using germanium.

  In view of the above circumstances, it is an object of the present invention to provide a resin film that is easily crystallized while keeping the manufacturing cost low, and a foamed molded article having excellent diffuse reflectance obtained by using this resin film. Raised.

The resin composition for a foam molded article of the present invention that has solved the above problems is a resin composition for making a foam molded article by heating after impregnating a resin sheet for a foam molded article with a non-reactive gas. The resin composition includes a polyester resin, and the polyester resin is composed of 75 to 98 mol% of ethylene terephthalate units and 2 to 25 mol% of amorphous units, with 100 mol% of all the structural units of the polyester. It is characterized by.

  In the present specification, units other than the ethylene terephthalate unit constituting the polyester are included in the amorphous unit.

  In the present invention, the amorphous unit is at least one selected from the group consisting of a diethylene terephthalate unit, a neopentyl terephthalate unit, a 1,4-cyclohexanedimethylene terephthalate unit, a propylene terephthalate unit, and an ethylene isophthalate unit. Is a preferred embodiment.

  Moreover, the resin composition for foam molded bodies of the present invention is a preferred embodiment in which the resin composition further contains a polyolefin, and the content of the polyolefin is 0.1 to 40% by mass.

  Further, when the crystallinity after impregnation with the non-reactive gas is evaluated by the method described later, it is preferable that the time required for the crystallinity to exceed 25% is within 42 hours.

  The present invention includes a resin sheet for foam molding (including a film) obtained from the above resin composition for foam molded article.

  In addition, the present invention includes a foam molded article obtained from the above foam molding resin sheet.

  According to the present invention, a resin composition that easily crystallizes when a non-reactive gas is contained can be obtained while keeping the manufacturing cost low. Moreover, the foaming molding which is excellent in a diffuse reflectance was able to be obtained.

The resin composition for a foam molded article of the present invention relates to a resin composition for heating a resin sheet for a foam molded article with a non-reactive gas and then heating to form a foam molded article. Here, the resin composition according to the present invention is configured to contain a polyester resin, and the polyester resin is composed of 75 to 98 mol% of ethylene terephthalate units, 2 to 100 mol% of all the structural units of polyester, and 2 to amorphous units. Consists of 25 mol%. Hereinafter, the resin composition for foam molded articles of the present invention will be described.

(Ethylene terephthalate unit)
The polyester resin used in the present invention preferably contains 75 mol% or more (preferably 80 mol% or more, more preferably 85 mol% or more) of an ethylene terephthalate unit, and is 98 mol% or less (preferably 97 mol% or less, more Preferably it is 96.5 mol% or less, more preferably 96 mol% or less). When the content of the ethylene terephthalate unit is less than 75 mol%, the heat resistance and impact resistance of the obtained foamed molded product may be insufficient.

(Amorphous unit)
The amorphous unit constituting the polyester resin used in the present invention is 2 mol% or more (preferably 3 mol% or more, more preferably 3.5 mol% or more, more preferably 100 mol% of all the structural units of the polyester. 4.0 mol% or more), preferably 25 mol% or less (preferably 20 mol% or less, more preferably 15 mol% or less). When the content rate of the amorphous unit is less than 2 mol%, the crystallization rate may be slow when the resin sheet obtained from the resin composition for foamed molded article is impregnated with a non-reactive gas. Moreover, when it exceeds 25 mol%, since the content rate of an ethylene terephthalate unit will fall as a result, the heat resistance and impact resistance of the foaming molding obtained may become inadequate.

  Examples of the amorphous unit include a unit obtained by a condensation reaction of a polyvalent carboxylic acid component other than terephthalic acid and a polyhydric alcohol component other than ethylene glycol, as will be described later. In particular, a diethylene terephthalate unit, a neopentyl terephthalate unit, a 1,4-cyclohexanedimethylene terephthalate unit, a propylene terephthalate unit, and an ethylene isophthalate unit are preferable. As will be described later, the polyester resin used in the present invention may include only one of these amorphous units or may include two or more.

(Characteristics of polyester resin)
The intrinsic viscosity of the polyester resin used in the present invention is 0.6 dl / g or more (preferably 0.7 dl / g or more, more preferably 0.8 dl / g or more, more preferably 0, as measured by the method described later. 0.9 dl / g or more). Since the polyester resin used in the present invention is a resin composition for foamed molded articles, mechanical properties and impact strength may be lowered when the intrinsic viscosity is less than 0.6 dl / g.

(Polyester resin content)
The resin composition for a foam molded body according to the present invention preferably contains 60% by mass (more preferably 70% by mass or more, and still more preferably 80% by mass or more) of the polyester resin. When the content rate of the polyester resin is less than 60% by mass, the heat resistance and rigidity of the foamed molded article obtained using this polyester resin are remarkably unfavorable.

(Production method of polyester resin)
The production method of the polyester resin used in the present invention is not particularly limited as long as all the structural units of the polyester are in the above embodiment. For example, the esterification reaction using terephthalic acid and ethylene glycol as main components. , Melt polycondensation, and solid state polymerization. Further, instead of terephthalic acid, an ester exchange reaction may be performed using an ester such as dimethyl terephthalate.

<Esterification reaction>
The esterification reaction of the raw material component mainly composed of terephthalic acid and ethylene glycol can be carried out by stirring the raw material component at 150 to 300 ° C. under normal pressure to pressure. At this time, the raw material components may be stirred in the presence of nitrogen gas.

  As a raw material component used when performing esterification reaction, other components (polyhydric carboxylic acid, polyhydric alcohol) may be contained in addition to the terephthalic acid and ethylene glycol.

  For example, polyvalent carboxylic acids other than terephthalic acid include isophthalic acid, naphthalene-1,4- or -2,6-dicarboxylic acid, 5-sodium sulfoisophthalic acid, 4,4′-diphenyldicarboxylic acid, diphenylsulfodicarboxylic acid. Aromatic dicarboxylic acids such as acids, glutaric acid, adipic acid, sebacic acid, azelaic acid, oxalic acid, succinic acid, etc., and aliphatic dicarboxylic acids, trimellitic acid, pyromellitic acid and their commonly called dimer acid Aromatic polyvalent carboxylic acids such as acid anhydrides may be mentioned. In the present invention, it is preferable to use isophthalic acid as the polyvalent carboxylic acid component so that an amorphous unit is included in the constituent unit of the polyester.

  In addition, as polyhydric alcohols other than ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, 1,4-butanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, Aliphatic diols such as 2-methyl-1,5-pentanediol, 2,2-diethyl-1,3-propanediol, 1,9-nonanediol, 1,10-decanediol, 1,4-cyclohexanedimethanol Alicyclic diols such as 1,4-cyclohexanediethanol, and aliphatic polyhydric alcohols such as trimethylolpropane and pentaerythritol. In the present invention, it is preferable to use diethylene glycol, neopentyl glycol, or 1,4-cyclohexanedimethanol as the polyhydric alcohol so that an amorphous unit is included in the constituent unit of the polyester.

<Melting polycondensation>
The melt polycondensation can be performed by adding a polycondensation catalyst to the reaction product obtained by the esterification reaction and stirring at 200 ° C. to 300 ° C. and 13.3 Pa to 3990 Pa.

  Various conventional catalysts can be used as the polycondensation catalyst, such as titanium-based catalysts (titanium tetrabutoxide, etc.), antimony-based catalysts (antimony trioxide, antimony acetate, etc.), germanium-based catalysts (germanium dioxide, etc.), cobalt-based catalysts. Examples thereof include catalysts (such as cobalt acetate), tin-based catalysts (such as monobutylhydroxytin oxide), manganese-based catalysts (such as manganese acetate), and aluminum-based catalysts (such as basic aluminum acetate). These polycondensation catalysts may be used alone or in combination of two or more. In the present invention, it is preferable to use a catalyst other than the germanium catalyst from the viewpoint of keeping the production cost of the foamed molded product low.

<Solid-state polymerization>
In the solid-phase polymerization, a polyester resin prepolymer obtained by melt polycondensation is cut while being cooled with water or the like to obtain chips having an average particle size of 1.5 mm to 5 mm, and then subjected to inert gas flow or reduced pressure. Below, it can carry out by heating at the temperature below melting | fusing point of a prepolymer, Preferably it is 1 to 30 hours.

  Prior to solid phase polymerization, precrystallization may be performed at a temperature lower than the temperature at which solid phase polymerization is performed. Thereby, solid phase polymerization can proceed more efficiently. This precrystallization step is performed, for example, by heating a prepolymer chip at 50 to 240 ° C. for 1 to 24 hours in an inert gas, under reduced pressure, or in an atmosphere of steam or a steam-containing inert gas. be able to.

  After cutting the polyester resin prepolymer into chips, fine powder contained in the prepolymer chips by passing through a sieve or by passing a cyclone air filter if the chips are air-fed It is preferable to remove the sheet-like material. Thereby, a long polyester resin sheet having a uniform composition can be obtained.

(Adjustment of amorphous unit content)
Examples of the method for changing the content of amorphous units in all the constituent units of the polyester resin to the above embodiment include (1) Polyhydric alcohol capable of constituting an amorphous unit in addition to terephthalic acid and ethylene glycol as raw material components The polyester resin obtained in the above aspect (1) is mixed with a method for producing a polyester resin using a component or a polycarboxylic acid component, or (2) a polyester resin produced using terephthalic acid and ethylene glycol. (3) A method for producing a polyester resin containing a diethylene terephthalate unit from terephthalic acid and ethylene glycol while appropriately selecting a polycondensation catalyst used in melt polycondensation, or (4) (1) to ( The combination of the manufacturing method of 3) etc. are mentioned.

(Polyolefin)
It is preferable that the resin composition for a foam molded article of the present invention further comprises a polyolefin in addition to the polyester resin. By foaming a resin sheet obtained from a resin composition comprising polyolefin, a foamed molded article having a high reflectance and containing uniform fine pores having an average cell diameter of 50 μm or less can be obtained. .

  The average bubble diameter is obtained by taking a SEM photograph of the cross section of the foam molded body, and calculating the diameter when the observed bubble is approximated to a sphere for any 30 bubbles included in the constant cross-sectional area of the foam layer. It can be obtained by averaging.

  The reason why a highly foamed and high-density foamed molded article with high reflectivity can be obtained by containing polyolefin is not clear, but the polyester resin is crystallized by containing a non-reactive gas in the polyester resin ( When the polyolefin dispersed in the polyester resin is used as a starting point for crystal nucleation, micro-crystals are formed, or the non-reactive gas is unevenly distributed or impregnated or contained in the polyolefin in a high concentration ("super" The latest application technology of critical fluids ”, pages 225 and 228-229, NTS Co., Ltd.), the starting point of bubble nucleation in the foaming process, or the dispersion diameter of polyolefin in polyester resin is on the micron order Due to the effect of fine foaming by finely dispersing from 1 to submicron Considered.

  Examples of the polyolefin used in the present invention include general-purpose low density polyethylene (LDPE), linear low density polyethylene (LLDPE), high density polyethylene (HDPE), polypropylene (PP), polymethylpentene (PMP), and ethylene series. Copolymer, styrene copolymer, and the like. Specifically, ethylene vinyl acetate (EVA), ethylene methyl methacrylate (EMMA), ethylene ethyl acrylate (EEA), ethylene methyl acrylate (EMA), Ethylene ethyl acrylate maleic anhydride (E-EA-MAH), ethylene acrylic acid (EAA), ethylene methacrylic acid (EMAA), ionomer (ethylene methacrylate metal cross-linking), MAH-G-polyolefin (maleic anhydride to PE and PP The Polymerized), ethylene glycidyl methacrylate (E-GMA), ethylene glycidyl methacrylate vinyl acetate (E-GMA-VA), ethylene glycidyl methacrylate methyl acrylate (E-GMA-MA), styrene-butadiene-styrene copolymer (SBS), styrene-ethylene / butylene-styrene copolymer (SEBS), styrene-isoprene-styrene copolymer (SIS), styrene-ethylene / propylene copolymer (SEP), styrene-ethylene / butylene-ethylene copolymer Examples thereof include a polymer (SEBC) and a hydrogenated styrene / butadiene copolymer (HSBR). Of these, SEBS and SEBC are more preferable.

  The polyolefin preferably has a functional group capable of chemically reacting or interacting with the polyester resin so as to be uniformly finely dispersed in the polyester resin. As functional groups, amino groups, epoxy groups, carboxyl groups (including acid anhydrides and carboxyl groups that are metal salts), hydroxyl groups, aldehyde groups, carbonyl groups, sulfo groups, nitro groups, halogen groups, oxazoline groups , An isocyanate group, and a thiol group.

  For example, when the functional group is an epoxy group, the functional group is introduced into the styrene-based copolymer by partially epoxidizing the diene component or graft-modifying an epoxy-containing compound such as glycidyl methacrylate. be able to.

  The content of the polyolefin in the resin composition of the present invention is 0.1% by mass or more (more preferably 0.5% by mass or more, more preferably 0.7% by mass) in 100% by mass of the resin composition for foam molded articles. Or more), preferably 40% by mass or less (more preferably 20% by mass or less, and still more preferably 5% by mass or less). When the content is less than 0.1% by mass, it is not easy to obtain a foamed product with high foaming and high density. Moreover, when it exceeds 40 mass%, since the content rate of the polyester resin in a resin composition falls as a result, the heat resistance of the foaming molding obtained, rigidity, and intensity | strength may fall.

(Crystallinity)
The resin composition for foam molding of the present invention has a CO ₂ exposure time of 42 hours or less (more preferably, crystallization) required for the crystallinity to exceed 25% when the crystallinity is evaluated by the following method. The CO ₂ exposure time required for the degree to exceed 25% is preferably within 36 hours). Thereby, since it becomes possible to make the resin sheet obtained from the resin composition of this invention into a foaming molding rapidly, it contributes to mass production of a foaming molding and can further suppress manufacturing cost.

[Crystallinity evaluation method]
From a resin sheet obtained from the resin composition for a foam molded article of the present invention, a sample piece having a size of 35 mm in length, 45 mm in width, and 0.6 mm in thickness was cut out, and a supercritical fluid processing test apparatus (model: HV1-SC) was obtained. And manufactured by Nisaka Seisakusho Co., Ltd.) and exposed to CO ₂ gas at 25 ° C. and 5 MPa for a predetermined time. H. X Air-dried for 48 hours. Next, the air-dried sample piece is set on a differential scanning calorimeter (EXSTAR6000, manufactured by SII Nano Technology, Inc., hereinafter sometimes simply referred to as “DSC”), and heated at 10 ° C./min. The amount of heat based on crystallization and melting of the sample piece was measured while calculating the crystallinity based on the following formula.
Crystallinity (%) = (A−B) / C
A: heat quantity based on melting B; heat quantity based on crystallization C; heat quantity of melting of 100% crystallized PET (117.6 J / g)

(Additive)
The resin composition for a foamed molded product of the present invention has various additives (for example, a crystallization nucleating agent such as talc, a bubble nucleating agent, etc., as long as the properties of the foamed molded product obtained by using the resin composition are not affected. , Antioxidants, antistatic agents, ultraviolet light inhibitors, light stabilizers, fluorescent brighteners, colorants, antibacterial agents, compatibilizers, lubricants, reinforcing agents, flame retardants, etc.).

  In particular, an alkali metal (such as lithium acetate), an alkaline earth metal (such as magnesium acetate), or a phosphorus-containing compound (such as trimethyl phosphate) is preferably added as an additive. By blending an alkali metal or an alkaline earth metal, the resin sheet is easily adhered to the roll when the resin sheet is obtained from the resin composition by a casting method based on the electrostatic adhesion system. Moreover, the resin composition excellent in thermal stability can be obtained by mix | blending a phosphorus containing compound.

(Foam molding)
Although it does not specifically limit as a method of obtaining a foaming molding using said resin composition for foaming moldings, For example, the following method is mentioned.

  That is, first, one or more of the above-mentioned polyester resin chips, polyolefin (chips), and various additives such as antistatic agents, if necessary, a dryer such as a hopper dryer or a paddle dryer, or a vacuum It dries using a dryer and extrudes into a film at a temperature of 200 to 300 ° C. using an extruder to produce a polyester resin sheet (unstretched). Alternatively, undried one or two or more kinds of polyester resin chips, polyolefin (chips), and various additives such as antistatic agents as necessary while removing moisture in a vented extruder. To form a polyester resin sheet (unstretched). When extruding, any existing method such as a T-die method or a tubular method may be adopted.

  After extrusion, quench with a casting roll. At that time, an electrode may be disposed between the extruder and the casting roll, and a voltage may be applied between the electrode and the casting roll to electrostatically adhere the sheet to the roll.

  Next, the polyester resin sheet and the separator are overlapped and wound to form a roll, and this roll is held in a pressurized nonreactive gas atmosphere to impregnate the polyester resin sheet with the nonreactive gas.

  Here, examples of the non-reactive gas that can be used in the present invention include carbon dioxide, helium, nitrogen, argon, and the like, and carbon dioxide is more preferable in consideration of gas permeability (rate, solubility) to the resin. .

The non-reactive gas permeation treatment time and permeation amount into the polyester resin sheet are appropriately adjusted depending on the type of resin to be foamed, the type of non-reactive gas, the permeation pressure, and the thickness of the sheet. The aspect which impregnates a polyester resin sheet with non-reactive gas under 5.0-7.1MPa is mentioned. Specifically, when the polyester resin sheet of the present invention is impregnated with carbon dioxide, the crystallinity of the polyester resin sheet is reduced in a chamber filled with CO ₂ gas at 25 ° C. and under 6.4 MPa. Hold the roll until 25%.

  In addition, you may perform the impregnation of the non-reactive gas to a polyester resin sheet in a supercritical state.

  Thereafter, the polyester resin sheet impregnated with the non-reactive gas is heated to a temperature equal to or higher than the softening temperature of the polyester resin and foamed under normal pressure. Specifically, in the present invention, the polyester resin sheet impregnated with the non-reactive gas is heated at 220 ° C. for 1 minute.

The apparent density of the obtained foamed molded product is preferably 100 to 1300 kg / m ³ .

<Application>
The foamed molded article of the present invention is excellent in reflectivity. Specifically, when measured by the method described later, the average reflectance in the light wavelength region of 400 to 700 nm is 90% or more. For this reason, it can be suitably used not only for electric signboards, lighting fixtures, and substrates for liquid crystal display reflectors but also for other applications where high reflectivity is required.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, and may be implemented with appropriate modifications within a range that can be adapted to the gist of the present invention. These are all included in the technical scope of the present invention. The measurement / evaluation methods employed in the examples are as follows. In the examples, “parts” means “parts by mass”, and “%” means “% by mass” unless otherwise specified.

(Measurement and evaluation method)
(1) Polyester resin composition The composition of the polyester resin used in the present invention was determined by dissolving 15 mg of a polyester resin sample in CDCl ₃ / CF ₃ COOH (85/15) and measuring H-NMR.

(2) Intrinsic viscosity The intrinsic viscosity IV (actual value) of the polyester resin used in the present invention is determined from the solution viscosity at 30 ° C. in a 1,1,2,2-tetrachloroethane / phenol (2: 3 weight ratio) mixed solvent. It was.

(3) Catalyst content The catalyst content in the polyester resin used in the present invention was determined by performing elemental analysis by X-ray photoelectron spectroscopy.

(4) Crystallinity Sample piece having a size of 35 mm in length, 45 mm in width, and 0.6 mm in thickness is cut out from the resin sheet obtained from the resin composition for foam molded article of the present invention, and a supercritical fluid processing test apparatus is used. (Model: HV1-SC, manufactured by Nisaka Seisakusho Co., Ltd.) and exposed to CO ₂ gas at 25 ° C. and 5 MPa for a predetermined time. % R. H. X Air-dried for 48 hours. Next, the air-dried sample piece is set on a differential scanning calorimeter (EXSTAR6000, manufactured by SII Nano Technology, Inc., hereinafter sometimes simply referred to as “DSC”), and heated at 10 ° C./min. The amount of heat based on crystallization and melting of the sample piece was measured while calculating the crystallinity based on the following formula.
Crystallinity (%) = (A−B) / C
A: heat quantity based on melting B; heat quantity based on crystallization C; heat quantity of melting of 100% crystallized PET (117.6 J / g)

(5) Diffuse reflectance Using a spectrophotometer (UV-3150; manufactured by Shimadzu Corporation), the reflectance of the foamed molded product in the light wavelength region of 400 to 700 nm is measured, and the reflectance is measured at 1 nm intervals from the obtained chart. The average value was measured. In Table 3 below, the diffuse reflectance of a white plate obtained by solidifying fine powder of barium sulfate (manufactured by Wako Pure Chemical Industries, Ltd., Wako Grade 1) is 100%, and the diffuse reflectance of each foamed molded product is expressed as a relative value. Show.

(Synthesis Example 1)
A heat medium circulating esterification reactor with a stirrer made of Hastelloy was charged with 100 mol% of high-purity terephthalic acid and 100 mol% of ethylene glycol, and 0.3 mol% of triethylamine was added to the total acid components, The esterification reaction was carried out for 2 hours while distilling water out of the system at 245 ° C. under pressure, and a mixture of bis (2-hydroxyethyl) terephthalate and oligomer having an esterification rate of 95% (hereinafter referred to as BHET mixture). Got. The BHET mixture was transported to a Hastelloy-made polycondensator with a stirrer, and antimony trioxide as a polycondensation catalyst was added to a residual amount of Sb of 270 ppm. Subsequently, it stirred at 245 degreeC for 10 minutes by the normal pressure in nitrogen atmosphere. Thereafter, while maintaining the temperature at 245 ° C., the pressure in the reaction system is gradually decreased to 13.3 Pa, and the first stage initial polycondensation is carried out for 50 minutes. Further, at 275 ° C. and 13.3 Pa, the IV is about 0.65 deciliter / The polycondensation reaction was carried out until grams. Subsequent to releasing the pressure, the prepolymer under slight pressure was discharged into cooling water in the form of a strand and rapidly cooled, and formed into a chip with a strand cutter to obtain a cylindrical chip. At the time of chip formation, the resin temperature from the polycondenser outlet to the nozzle pores was about 270 ° C., and the entire amount was chipped within about 30 minutes.

  The cooling water is obtained by treating industrial water (derived from river underground water) with a filter filtration device and an ion exchange device. The cooling water contains about 500 particles / 10 ml of particles having a particle size of 1 to 25 μm and has a sodium content of 0. 0.02 ppm (mass basis, the same shall apply hereinafter), magnesium content is 0.01 ppm, calcium content is 0.01 ppm, and silicon content is 0.11 ppm.

  Next, the obtained chip is immediately heat-treated at about 50 to about 150 ° C. in a vacuum dryer, treated by a vibration sieving step and an airflow classification step to remove fine powder and film-like material, and contain fine powder A crystallized prepolymer having an amount of about 50 ppm or less was obtained. The IV was 0.63 deciliter / gram.

Next, the crystallization prepolymer is sent to a crystallization apparatus, followed by crystallization at about 155 ° C. in a nitrogen atmosphere, and further preheated to about 200 ° C. in a nitrogen atmosphere, and then sent to a continuous solid-state polymerization reactor and about Solid state polymerization was performed at 205 ° C. After the solid-phase polymerization, the resin 1 for a foamed molded product having a fine powder content of about 50 ppm was obtained by removing the fine powder continuously by a sieving step and a fine powder removing step. The obtained resin 1 for foam molded articles had an intrinsic viscosity of 1.015 deciliter / gram, a cyclic trimer content of 0.40% by weight, and a density of 1410 kg / m ³ .

(Synthesis Example 2)
A resin 2 for foamed molded article was obtained in the same manner as in Synthesis Example 1 except that the solid phase polymerization time was extended to set the intrinsic viscosity of the polyester resin to 1.15 deciliter / gram in Synthesis Example 1.

(Synthesis Example 3)
In Synthesis Example 1, 100 mol% terephthalic acid, 83 mol% ethylene glycol, and 17 mol% neopentyl glycol were charged into the esterification reaction kettle, the esterification reaction was performed, and as a polycondensation catalyst In the same manner as in Synthesis Example 1 except that an ethylene glycol solution of a mixture of antimony trioxide, trimethyl phosphate, cobalt acetate, and sodium acetate was used, a resin 3 for a foam molded article was obtained.

(Synthesis Example 4)
In Synthesis Example 1, a resin 4 for foamed molded article was obtained in the same manner as in Synthesis Example 1 except that an ethylene glycol solution of a mixture of antimony trioxide, trimethyl phosphate and cobalt acetate was used as the polycondensation catalyst.

(Synthesis Example 5)
In Synthesis Example 1, a resin 5 for foam molded article was obtained in the same manner as in Synthesis Example 1 except that an ethylene glycol solution of a mixture of antimony trioxide, magnesium acetate, trimethyl phosphate and sodium acetate was used as the polycondensation catalyst. It was.

(Synthesis Example 6)
In Synthesis Example 1, a resin for foamed molded article was obtained in the same manner as in Synthesis Example 1 except that an ethylene glycol solution of a mixture of antimony trioxide, magnesium acetate, trimethyl phosphate, sodium acetate, and silicon oxide was used as the polycondensation catalyst. 6 was obtained.

(Synthesis Example 7)
In Synthesis Example 1, 90 mol% of high-purity terephthalic acid, 10 mol% of isophthalic acid, 100 mol% of ethylene glycol as a glycol component were used, and an ethylene glycol solution of titanium tetrabutoxide was used as a polymerization catalyst. Except that, Resin 7 for Foam Molded Body was obtained in the same manner as in Synthesis Example 1.

  Table 1 shows the compositions and physical properties of the resins 1 to 7 for foamed molded products. In addition, the composition and physical properties of other resins used in the following examples are also shown.

  In addition, the polymerization catalyst amount in Table 1 means the mass in terms of each metal relative to the total mass of the raw material components.

  In Table 1, ET means ethylene terephthalate unit, DET means diethylene terephthalate unit, NPT means neopentyl terephthalate unit, EIP means ethylene isophthalate unit, and CHDT means 1,4-cyclohexanedimethylene terephthalate unit.

Example 1
As the polyester resin, 96.8 parts by mass of resin 1 for foam molded body, 2.0 parts by mass of resin 3 for foam molded body, and styrene-ethylene / butylene-styrene copolymer (SEBS) as polyolefin are separately dried. , Manufactured by JSR Co., Ltd.) 1.0 part by mass, antistatic agent (alkane sulfonic acid soda, Matsumoto Yushi Seiyaku Co., Ltd.) 0.2 part by mass, supplied to the hopper directly above the extruder and mixed, and then heated to 280 ° C. It melt-extruded using the temperature-controlled twin-screw extruder, quenched with a 40 degreeC cooling roll, and wound up, and the resin sheet 1 about 0.6 mm thick was obtained. A part of the resin sheet 1 was cut for measuring the degree of crystallinity, and then the rest was foamed by the following method to obtain a foam molded article 1.

That is, a roll was formed by wrapping the resin sheet 1 and a separator (olefin-based non-woven fabric (FT300 grade, manufactured by Nippon Vileen Co., Ltd.)), and the roll was filled with CO ₂ at 25 ° C. and 6.4 MPa. Holding in the chamber, the resin sheet 1 is impregnated with CO ₂ gas until the crystallinity of the resin sheet 1 reaches 25%. The roll was taken out from the pressure vessel, and while removing the separator, only the resin sheet 1 infiltrated with CO ₂ gas was continuously supplied to the hot-air circulating foaming furnace set at 220 ° C. so that the foaming time was 1 minute, and foamed. . The obtained foamed molded body 1 had a thickness of 1000 μm and an average cell diameter of 1 μm.

(Example 2)
In Example 1, resin sheet 2 was obtained in the same manner as in Example 1 except that 94.8 parts by mass of foam molded body resin 1 and 4.0 parts by mass of foam molded body resin 3 were used as the polyester resin. And the foaming molding 2 was obtained.

(Example 3)
In Example 1, resin sheet 3 was obtained in the same manner as in Example 1 except that 92.8 parts by mass of foam molded body resin 1 and 6.0 parts by mass of foam molded body resin 3 were used as the polyester resin. And the foaming molding 3 was obtained.

Example 4
In Example 1, resin sheet 4 was obtained in the same manner as in Example 1 except that 90.8 parts by mass of foam molded body resin 1 and 8.0 parts by mass of foam molded body resin 3 were used as the polyester resin. And the foaming molding 4 was obtained.

(Example 5)
In Example 1, resin sheet 5 was obtained in the same manner as Example 1 except that 88.8 parts by mass of foam molded body resin 1 and 10.0 parts by mass of foam molded body resin 3 were used as the polyester resin. And the foaming molding 5 was obtained.

(Example 6)
In Example 1, resin sheet 6 was obtained in the same manner as in Example 1 except that 78.8 parts by mass of foam molded body resin 1 and 20.0 parts by mass of foam molded body resin 3 were used as the polyester resin. And the foaming molding 6 was obtained.

(Example 7)
In Example 5, a resin sheet 7 and a foamed molded body 7 were obtained in the same manner as in Example 5 except that PETG (registered trademark, manufactured by Eastman Chemical Co., Ltd.) was used instead of the resin 3 for foamed molded body. It was.

(Example 8)
In Example 6, a resin sheet 8 and a foamed molded body 8 were obtained in the same manner as in Example 6 except that PETG (registered trademark, manufactured by Eastman Chemical Co.) was used instead of the resin 3 for foamed molded body. It was.

Example 9
In Example 1, as the polyester resin, 54.8 parts by mass of the resin 2 for foam molded body, 38.0 parts by mass of resin 4 for foam molded body, and 6.0 parts by mass of resin 3 for foam molded body were used. Obtained a resin sheet 9 and a foamed molded body 9 in the same manner as in Example 1.

(Example 10)
In Example 9, the resin sheet 10 and the foam molded body 10 were obtained in the same manner as in Example 9 except that the resin 5 for foam molded body was used instead of the resin 4 for foam molded body as the polyester resin. .

(Example 11)
In Example 9, a resin sheet 11 and a foam molded body 11 were obtained in the same manner as in Example 9 except that the resin 6 for foam molded body was used instead of the resin 4 for foam molded body as the polyester resin. .

(Example 12)
In Example 11, a resin sheet 12 and a foam molded body 12 were obtained in the same manner as in Example 11 except that the thickness of the resin sheet was changed to 400 μm.

(Example 13)
In Example 1, as a polyester resin, in place of the foam molded body resin 1 and 3, in the same manner as in Example 1 except that 98.8 parts by mass of the foam molded body resin 7 was used, A foam molded body 13 was obtained.

(Comparative Example 1)
In Example 1, in place of Resin 1 for Foam Molded Body 1 and 3 as the polyester resin, 98.8 parts by mass of Resin 1 for Foam Molded Body was used in the same manner as in Example 1, A foam molding 14 was obtained.

(Reference Example 1)
In Example 1, as a polyester resin, in place of Resin 1 and 3 for foam-molded bodies, SA 1206 (manufactured by Unitika Ltd.) was used in the same manner as in Example 1 except that 98.8 parts by mass was used. And the foaming molding 15 was obtained.

  The crystallinity of the obtained resin sheets 1 to 15 was measured by the above method. Moreover, the diffuse reflectance was measured by the said method about the foaming molding 3, 5, 7, 9, 13-15. The results are shown in Tables 2-1 to 2-3 and Table 3.

Crystallization of the measurement results of the resin sheet 1 to 15, CO ₂ processing time on the horizontal axis, showing a chart plotting the crystallinity on the vertical axis.

  1-3, it turned out that the crystallization speed | rate of a resin sheet increases by making the content rate of the amorphous unit in a polyester resin into 2 mol% or more.

  Further, FIG. 2 shows that the crystallization speed of the resin sheet has selectivity depending on the specific mode of the amorphous unit.

  From FIG. 4, it was found that even when a catalyst other than germanium was used as the polycondensation catalyst, a resin sheet having a faster crystallization rate than a resin sheet obtained using germanium was obtained.

  From Table 3, it was found that even when a catalyst other than germanium was used as the polycondensation catalyst, a foam molded article having an average diffuse reflectance superior to that of the foam molded article obtained using germanium was obtained.

  The resin composition for a foam molded article of the present invention can produce a resin sheet excellent in crystallinity at low cost. Moreover, since it is excellent in a diffuse reflectance, it is suitable as reflector applications, such as an electrical decoration signboard, a lighting fixture, and a liquid crystal display.

It is a figure which shows the crystallinity degree of the resin sheets 1-6, and 14. FIG. It is a figure which shows the crystallinity degree of the resin sheets 5-8, and 14. FIG. It is a figure which shows the crystallinity degree of the resin sheets 9-14. It is a figure which shows the crystallinity degree of the resin sheets 4, 9, 11, and 15.

Claims (1)

A resin composition for a foam molded article comprising a polyester resin, wherein the polyester resin is composed of 75 to 98 mol% of an ethylene terephthalate unit and 2 to 25 mol% of an amorphous unit, based on 100 mol% of all structural units of the polyester . The foam molded body resin sheet obtained from the above is maintained in a pressurized nonreactive gas atmosphere and impregnated with the nonreactive gas, and then the resin sheet impregnated with the nonreactive gas is subjected to normal pressure under the polyester resin. A method for producing a foamed molded article, wherein the foamed product is heated to a temperature equal to or higher than a softening temperature.

Images