WO2010110420A1 - Porous molded object and process for producing same - Google Patents

Abstract

A porous molded object having excellent heat-insulating properties and high brightness, and a process for producing the molded object. The process for producing the porous molded object is characterized by cooling a parison comprising a crystalline polymer and/or a polymer containing fine particles, thereby forming particles serving as seed particles for void formation, and blow-molding the parison to produce a molded object having voids therein.

Description

Porous molded body and method for producing the same

The present invention relates to a porous molded body and a method for manufacturing the same, and more particularly to a porous molded body molded by blow molding and a method for manufacturing the same.

For blow molding, the molded parison (preform) is once cooled to room temperature, reheated with a blow molding device to adjust the temperature, and blow molded, and the molded parison is not cooled completely. There is a hot parison system that moves to a temperature adjustment process and then blow-molds (see, for example, Patent Document 1).
In the cold parison method, for example, as shown in FIGS. 1A and 1B, a bottomed cylindrical parison 10 that has been molded in advance is set in the blow molding apparatus 1 (FIG. 1A), and then the mold 20a, In this method, the molded body 30 is manufactured by superimposing and heating 20b, supplying air from above, and causing the parison 10 to follow the inner surface shape of the mold 20 (FIG. 1B).
In the hot parison system, for example, as shown in FIGS. 2A and 2B, the parison 10 is extruded in a molten state in a tube shape (FIG. 2A), and then the molds 20a and 20b are overlapped, and the parison 10 is completely cooled. In this state, air is supplied from below and the parison 10 is made to follow the inner surface shape of the mold 20 to produce the molded body 30 (FIG. 2B).
The molded body 30 manufactured by such blow molding is excellent in transparency, impact resistance, hygiene, gas barrier properties, pressure resistance, and the like. For this purpose, various foods, beverages, detergents, cosmetics, etc. Widely used as a packaging container (see, for example, Patent Document 2).
A high-temperature or low-temperature substance may be charged or injected into the packaging container, and it is desired to improve the heat insulation of the packaging container. In addition, from the viewpoint of aesthetics, it is also desired to increase the brightness of packaging containers.
However, a high-brightness blow molded article excellent in heat insulation has not yet existed.

International Publication No. 00/23252 Pamphlet JP-A-7-257534

This invention makes it a subject to solve the said various problems in the past and to achieve the following objectives. That is, an object of the present invention is to provide a high-luminance porous molded body excellent in heat insulation and a method for producing the same.

Means for solving the problems are as follows. That is,
<1> A porous body characterized in that a parison containing at least one of a crystalline polymer and a fine particle-containing polymer is cooled to form cavity-origin particles and blow-molded to produce a molded body having a cavity inside. It is a manufacturing method of a quality molded object.
In the method for producing a porous molded body, a parison including at least one of a crystalline polymer and a fine particle-containing polymer is cooled to form cavity-starting particles, which are then blow-molded to have a cavity inside. Is manufactured.
<2> The method for producing a porous molded body according to <1>, wherein the parison is cooled to a temperature not higher than 10 ° C. higher than the glass transition temperature of the parison.
<3> The method for producing a porous molded body according to any one of <1> to <2>, wherein the parison is cooled below the glass transition temperature of the parison.
<4> The method for producing a porous molded body according to any one of <1> to <3>, wherein the cooling rate of the parison at the time of forming the cavity starting particles is 5 ° C./sec to 200 ° C./sec. .
<5> The method for producing a porous molded body according to any one of <1> to <4>, wherein the stretch rate of the parison in blow molding is 10 mm / min to 40,000 mm / min.
<6> The method for producing a porous molded article according to any one of <1> to <5>, wherein the crystalline polymer contains at least one of polyethylene terephthalate and polybutylene terephthalate.
<7> The method for producing a porous molded body according to any one of <1> to <6>, wherein the fine particles have a volume average particle diameter of 0.01 μm to 10 μm.
<8> The method for producing a porous molded body according to any one of <1> to <7>, wherein the fine particles are either an organic filler or an inorganic filler.
<9> The method for producing a porous molded body according to any one of <1> to <7>, wherein the fine particles are resin fine particles incompatible with the fine particle-containing polymer.
<10> The porous molded body according to any one of <1> to <9>, further comprising blow molding a parison in a mold and transferring the inner surface shape of the mold to the parison. It is a manufacturing method.
<11> The method for producing a porous molded body according to <10>, further comprising heating the parison in the mold.
<12> The method for producing a porous molded body according to any one of <10> to <11>, wherein the cavity formation and the transfer are performed by the same blow molding.
<13> A porous molded body produced by the method for producing a porous molded body according to any one of <1> to <12>.

According to the present invention, the above-mentioned problems can be solved, the object can be achieved, and a high-luminance porous molded body excellent in heat insulation and a method for producing the same can be provided.

FIG. 1A is a diagram for explaining a cold parison system in blow molding (part 1). FIG. 1B is a diagram for explaining a cold parison method in blow molding (part 2). FIG. 2A is a diagram for explaining a hot parison system in blow molding (part 1). FIG. 2B is a diagram for explaining a hot parison system in blow molding (part 2).

(Method for producing porous molded body and porous molded body)
The porous molded body of the present invention can be preferably manufactured by the manufacturing method of the present invention. Hereinafter, the manufacturing method of the porous molded object of this invention and the porous molded object manufactured by this method are demonstrated.
The method for producing a porous molded body of the present invention includes at least a cavity starting particle forming step and a cavity forming step, and further includes other steps as necessary.

<Cavity origin particle formation process>
The cavity starting particle forming step is a step of cooling the parison including at least one of the crystalline polymer and the fine particle-containing polymer to form the cavity starting particle inside the parison.
When the parison is made of a crystalline polymer, the parison is crystallized by the cooling to form microcrystals inside the parison, and the microcrystals become cavity starting particles.
When the parison is made of a fine particle-containing polymer, the fine particles in the fine particle-containing polymer become cavity starting particles.

<< Parison >>
There is no restriction | limiting in particular as a shaping | molding method of the said parison, According to the objective, it can select suitably, For example, extrusion molding, injection molding, etc. are mentioned.
The shape of the parison is not particularly limited as long as it is a hollow shape, and can be appropriately selected according to the purpose. Examples thereof include a bottomed cylindrical shape and a tube shape.
There is no restriction | limiting in particular as a structure of the said parison, According to the objective, it can select suitably, For example, a single layer structure, a multilayer structure, etc. are mentioned.
There is no restriction | limiting in particular as a magnitude | size of the said parison, According to the objective, it can select suitably.
The parison includes at least one of a crystalline polymer and a fine particle-containing polymer, and further includes other components as necessary.

-Crystalline polymer-
In general, polymers are classified into crystalline polymers and amorphous (amorphous) polymers, but even crystalline polymers are not 100% crystalline, and long chain molecules are regularly formed in the molecular structure. It includes aligned crystalline regions and non-regularly arranged amorphous (amorphous) regions.
Therefore, the crystalline polymer only needs to include at least the crystalline region in the molecular structure, and the crystalline region and the amorphous region may be mixed.

There is no restriction | limiting in particular as said crystalline polymer, According to the objective, it can select suitably, For example, polyolefin (for example, low density polyethylene, high density polyethylene, polypropylene, etc.), polyamides (PA) (for example, Nylon-6, etc.), polyacetals (POM), polyesters (eg, PET, PEN, PTT, PBT, PPT, PHT, PBN, PES, PBS, etc.), syndiotactic polystyrene (SPS), polyphenylene sulfide ( PPS), polyether ether ketones (PEEK), liquid crystal polymers (LCP), fluororesin, isotactic polypropylene (isoPP), and the like. Among them, polyolefins, polyesters, syndiotactic polystyrene (SPS) and liquid crystal polymers (LCP) are preferable from the viewpoint of durability, mechanical strength, production and cost, and polyolefins (PP, PE, etc.), polyesters Are more preferred, and PET is particularly preferred. Two or more kinds of these polymers may be blended or copolymerized.

In order to reduce the light transmittance in the ultraviolet region of the porous molded body (enhance reflection characteristics), the crystalline polymer may not contain a functional group having high absorption in the ultraviolet region, such as an aromatic ring. preferable. Therefore, aliphatic polyester is preferable among the polyesters.

The melt viscosity of the crystalline polymer is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 50 Pa · s to 700 Pa · s, more preferably 70 Pa · s to 500 Pa · s, and more preferably 80 Pa · s. Particularly preferred is s to 300 Pa · s. The melt viscosity of 50 Pa · s to 700 Pa · s is preferable in that the shape of the polymer discharged from the die head at the time of melting is stabilized. Further, the melt viscosity of 50 Pa · s to 700 Pa · s is preferable in that the viscosity at the time of melting becomes appropriate and the extrusion becomes easy.
Here, the melt viscosity can be measured by a plate type rheometer or a capillary rheometer.

The intrinsic viscosity (IV) of the crystalline polymer is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0.4 to 1.5, more preferably 0.6 to 1.4. 0.7 to 1.3 is particularly preferable. The IV of 0.4 to 1.5 is preferable in that the strength of the porous molded body is increased and the film can be efficiently stretched.
Here, the IV can be measured by an Ubbelohde viscometer.

The melting point (Tm) of the crystalline polymer is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 40 ° C to 350 ° C, more preferably 100 ° C to 300 ° C, and more preferably 100 ° C to 260 ° C. ° C is particularly preferred. The melting point of 40 ° C. to 350 ° C. is preferable in that the shape can be easily maintained in the temperature range expected for normal use.
Here, the melting point can be measured by a differential thermal analyzer (DSC).

The content of the crystalline polymer is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 80% by mass to 99.5% by mass, and 85% by mass to 99% by mass with respect to the parison. % Is more preferable, and 90% by mass to 98% by mass is particularly preferable.
When the content of the crystalline polymer is less than 80% by mass with respect to the parison, it may be difficult to maintain the shape during processing and handling of the parison. When the content exceeds 99.5% by mass, the parison May become brittle.

--- Polyester resin--
The polyesters (hereinafter referred to as “polyester resins”) mean a general term for polymer compounds having an ester bond as a main bond chain. Accordingly, examples of the polyester resin suitable as the crystalline polymer include the exemplified PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PTT (polytrimethylene terephthalate), PBT (polybutylene terephthalate), PPT ( Polycondensation of polypentamethylene terephthalate), PHT (polyhexamethylene terephthalate), PBN (polybutylene naphthalate), PES (polyethylene succinate), PBS (polybutylene succinate), dicarboxylic acid component and diol component All polymer compounds obtained by the reaction are included.

The dicarboxylic acid component is not particularly limited and may be appropriately selected depending on the intended purpose. For example, aromatic dicarboxylic acid, aliphatic dicarboxylic acid, alicyclic dicarboxylic acid, oxycarboxylic acid, polyfunctional acid, etc. Is mentioned.

The aromatic dicarboxylic acid is not particularly limited and may be appropriately selected depending on the intended purpose. For example, terephthalic acid, isophthalic acid, diphenyldicarboxylic acid, diphenylsulfone dicarboxylic acid, naphthalenedicarboxylic acid, diphenoxyethanedicarboxylic acid , 5-sodium sulfoisophthalic acid, and the like. Among these, terephthalic acid, isophthalic acid, diphenyldicarboxylic acid, and naphthalenedicarboxylic acid are preferable, and terephthalic acid, diphenyldicarboxylic acid, and naphthalenedicarboxylic acid are more preferable.

The aliphatic dicarboxylic acid is not particularly limited and may be appropriately selected depending on the intended purpose. For example, oxalic acid, succinic acid, eicoic acid, adipic acid, sebacic acid, dimer acid, dodecanedioic acid, maleic acid , Fumaric acid, and the like. There is no restriction | limiting in particular as said alicyclic dicarboxylic acid, According to the objective, it can select suitably, For example, cyclohexane dicarboxylic acid etc. are mentioned. The oxycarboxylic acid is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include p-oxybenzoic acid. There is no restriction | limiting in particular as said polyfunctional acid, According to the objective, it can select suitably, For example, trimellitic acid, pyromellitic acid, etc. are mentioned. Among the aliphatic dicarboxylic acids and alicyclic dicarboxylic acids, succinic acid, adipic acid, and cyclohexane are used in that the porous molded body has low transmittance (excellent reflection characteristics) in a wide wavelength range including the ultraviolet region. Dicarboxylic acids are preferred, and succinic acid and adipic acid are more preferred.

The diol component is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include aliphatic diols, alicyclic diols, aromatic diols, diethylene glycol, and polyalkylene glycols. Among these, aliphatic diols are preferable in that the porous molded body has low transmittance (excellent reflection characteristics) in a wide wavelength range including the ultraviolet region.

The aliphatic diol is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include ethylene glycol, propane diol, butane diol, pentane diol, hexane diol, neopentyl glycol, and triethylene glycol. Can be mentioned. Of these, propanediol, butanediol, pentanediol, and hexanediol are preferable. There is no restriction | limiting in particular as said alicyclic diol, According to the objective, it can select suitably, For example, cyclohexane dimethanol etc. are mentioned. There is no restriction | limiting in particular as said aromatic diol, According to the objective, it can select suitably, For example, bisphenol A, bisphenol S, etc. are mentioned.

The melt viscosity of the polyester resin is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 50 Pa · s to 700 Pa · s, more preferably 70 Pa · s to 500 Pa · s, and more preferably 80 Pa · s. ˜300 Pa · s is particularly preferred. When the melt viscosity is higher, voids are more likely to be generated during stretching. However, when the melt viscosity is 50 Pa · s to 700 Pa · s, extrusion becomes easier and the resin flow becomes stable and retention is less likely to occur. It is preferable in that the quality is stabilized. Further, the melt viscosity of 50 Pa · s to 700 Pa · s is preferable in that the drawing tension is appropriately maintained at the time of drawing, and it becomes easy to draw uniformly and is difficult to break. Further, when the melt viscosity is 50 Pa · s to 700 Pa · s or more, it becomes easy to maintain the form of the discharged material discharged from the die head, and it can be stably molded, and the product is not easily damaged. , Which is preferable in terms of enhancing physical properties.

The intrinsic viscosity (IV) of the polyester resin is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0.4 to 1.5, more preferably 0.6 to 1.3, Particularly preferred is 0.7 to 1.2. When the IV is larger, voids are more likely to be generated during stretching. However, when the IV is 0.4 to 1.5, extrusion becomes easier and the resin flow is more stable, and it is difficult for retention to occur. Is preferable in that it is stabilized. Further, when the IV is 0.4 to 1.5, the stretching tension is appropriately maintained at the time of stretching, so that it is easy to stretch uniformly and it is preferable in that the load is not easily applied to the apparatus. In addition, when the IV is 0.4 to 1.5, it is preferable in that the product is hardly damaged and the physical properties are increased.

The melting point of the polyester resin is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 70 ° C. to 300 ° C., more preferably 90 ° C. to 270 ° C. from the viewpoint of heat resistance.

In addition, as said polyester resin, the said dicarboxylic acid component and the said diol component may respectively superpose | polymerize with 1 type, and may form the polymer, and the said dicarboxylic acid component and / or the said diol component are 2 or more types. A polymer may be formed by copolymerization. Further, as the polyester resin, two or more kinds of polymers may be blended and used.

In the blend of two or more polymers, the polymer added to the main polymer has a melt viscosity and an intrinsic viscosity that are close to those of the main polymer, and the addition amount is smaller, and the physical properties at the time of melt extrusion are smaller. It is preferable in terms of increasing and facilitating extrusion.

In addition, for the purpose of improving the flow characteristics of the polyester resin, controlling light transmittance, and improving the adhesion with the coating solution, a resin other than polyester may be added to the polyester resin.

-Fine particle-containing polymer-
The fine particle-containing polymer is not particularly limited as long as it contains fine particles, and can be appropriately selected according to the purpose. For example, the above-described crystalline polymer, polyvinyl chloride, atactic polystyrene, polymethyl methacrylate, etc. Non-crystalline polymer, and the like.

--- Fine particles--
The fine particles are not particularly limited as long as they can serve as cavity starting particles, and can be appropriately selected according to the purpose. Examples thereof include fillers and resin fine particles.
The filler is not particularly limited and may be appropriately selected depending on the intended purpose.For example, sodium stearate salt, montanic acid sodium salt, aluminum benzoate, sodium adipate, pt-butylbenzoate aluminum salt, Examples thereof include organic fillers such as hydroxystearic acid amide and ricinoleic acid amide, inorganic fillers such as talc, silica, kaolin, clay, smectite, and vermiculite.
The resin fine particles are not particularly limited as long as they are incompatible with the fine particle-containing polymer, and can be appropriately selected according to the purpose. Examples thereof include PTFE (polytetrafluoroethylene).
The content of the fine particles is not particularly limited and may be appropriately selected depending on the intended purpose. It is preferably 0.05% by mass to 5% by mass and preferably 0.1% by mass to 2% by mass with respect to the parison. % Is more preferable, and 0.2% by mass to 0.5% by mass is particularly preferable.
If the content of the fine particles is less than 0.05% with respect to the parison, sufficient crystallization may not be promoted, and if it exceeds 5 mass%, the parison may become brittle.
The volume average particle diameter of the fine particles is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0.01 μm to 10 μm, more preferably 0.02 μm to 5 μm, and more preferably 0.05 μm to 1 μm. Particularly preferred.
If the volume average particle size of the fine particles is less than 0.01 μm, sufficient crystallization may not be promoted, and if it exceeds 10 μm, the parison may become brittle.

-Other ingredients-
There is no restriction | limiting in particular as said other component, According to the objective, it can select suitably, For example, a crystal nucleating agent etc. are mentioned.

--- Crystal nucleating agent--
The crystal nucleating agent is not particularly limited as long as it promotes microcrystal formation inside the crystalline polymer, and can be appropriately selected according to the purpose. i) simple substances, metal compounds including complex oxides, (ii) low molecular compounds having a metal salt of a carboxyl group, (iii) high molecular organic compounds, (iv) phosphoric acid, phosphorous acid, or metal salts thereof ( v) sorbitol derivatives, (vi) quaternary ammonium compounds, (vii) other compounds, and the like. Moreover, the said crystal nucleating agent may use 1 type or 2 types or more simultaneously.
The metal compound containing (i) simple substance and complex oxide is not particularly limited and may be appropriately selected depending on the purpose. For example, calcium carbonate, synthetic silicic acid and silicate, silica, zinc white, high Examples include cytoclay, kaolin, basic magnesium carbonate, mica, talc, quartz powder, diatomaceous earth, dolomite powder, titanium oxide, zinc oxide, antimony oxide, barium sulfate, calcium sulfate, alumina, calcium silicate, and boron nitride.
Examples of the low molecular compound having a metal salt of (ii) carboxyl group include octylic acid, toluic acid, heptanoic acid, pelargonic acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, serotic acid, montanic acid, Melicic acid, benzoic acid, p-tert-butylbenzoic acid, terephthalic acid, terephthalic acid monomethyl ester, isophthalic acid, isophthalic acid monomethyl ester, camphoric acid, citronellic acid, hinokic acid, abitienic acid, rosin acid, hydrogenated rosin acid, etc. The metal salt is mentioned.
The (iii) polymer organic compound is not particularly limited and may be appropriately selected depending on the intended purpose. For example, 3,3-dimethylbutene-1, 3-methylpentene-1, 3-methylbutene-1 , 3-methylhexene-1, 3,5,5-trimethylhexene-1, etc., and 3-position branched α-olefins having 5 or more carbon atoms, and vinylcycloalkanes such as vinylcyclopentane, vinylcyclohexane, and vinylnorbornane. Polymers, polyalkylene glycols such as polyethylene glycol and polypropylene glycol, polyglycolic acid, cellulose, cellulose ester, cellulose ether, polyvinyl alcohol, chitin, chitosan, nylon 6, nylon 66, nylon 610, nylon 612 and other aliphatic polyamides Compound, tele Wholly aromatic polyester fine powder to the barrel acid and resorcinol as main constitutional units, polyhydroxyalkanoates, and the like.
The (iv) phosphoric acid, phosphorous acid, or a metal salt thereof is not particularly limited and may be appropriately selected depending on the intended purpose. For example, diphenyl phosphate, diphenyl phosphite, bis (4-tert-butyl phosphate) Phenyl) sodium, methylene phosphate (2,4-tert-butylphenyl) sodium, and the like.
The (v) sorbitol derivative is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include bis (p-methylbenzylidene) sorbitol and bis (p-ethylbenzylidene) sorbitol.
The (vi) quaternary ammonium compound is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include tetraethylammonium chloride, tetran-propylammonium chloride, tetran-butylammonium chloride, tetraethylammonium bromide. Tetra n-propylammonium bromide, tetra n-butylammonium bromide, tetraethylammonium silicate, tetra n-butylammonium silicate, and the like.
The (vii) other compound is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include thioglycolic anhydride, p-toluenesulfonic acid, and metal salts thereof, dibasic acid bis (benzoic acid) Acid hydrazide) compounds, isocyanurate compounds, compounds having a barbituric acid structure, and the like.
The content of the crystal nucleating agent is not particularly limited and may be appropriately selected depending on the intended purpose. It is preferably 0.01% by mass to 15% by mass with respect to the parison, and 0.05% by mass. Is more preferably 10% by mass, and particularly preferably 0.1% by mass to 3% by mass.
If the content of the crystal nucleating agent is less than 0.01% by mass relative to the parison, the effect may not be obtained sufficiently, and if it exceeds 15% by mass, the parison may become brittle. is there.
The volume average particle size of the crystal nucleating agent is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0.01 μm to 20 μm, more preferably 0.1 μm to 10 μm, and more preferably 0.2 μm. Particularly preferred is ˜3 μm.
If the volume average particle size of the crystal nucleating agent is less than 0.01 μm, the effect may not be sufficiently obtained, and if it exceeds 20 μm, the parison may become brittle.

<< Cooling >>
The cooling temperature is not particularly limited and may be appropriately selected depending on the intended purpose. However, it is preferably 10 ° C. or lower than the glass transition temperature of the parison, and is lower than the glass transition temperature of the parison. More preferably, from the viewpoint of blow moldability, the temperature is preferably 20 ° C. or lower than the glass transition temperature. When the temperature exceeds 10 ° C. higher than the glass transition temperature of the parison, the cavity starting particles may not be formed inside the parison. Moreover, even if it exceeds 10 degreeC higher than the glass transition temperature of a parison, when a cavity origin particle | grain is formed inside the said parison, if it cools to the temperature exceeding 10 degreeC higher than the glass transition temperature of a parison, It ’s enough.
The cooling rate is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 5 ° C / sec to 200 ° C / sec, more preferably 10 ° C / sec to 100 ° C / sec, It is particularly preferably from ℃ / sec to 60 ℃ / sec.
When the cooling rate is less than 5 ° C./sec, crystallization may proceed excessively, and when it exceeds 200 ° C./sec, crystallization may be insufficient.

<Cavity formation process>
The cavity forming step is a step of blow molding the parison in which the cavity starting particles are formed to produce a molded body having a cavity inside.

<< Blow molding >>
The blow molding is not particularly limited as long as the gas is supplied to the hollow portion of the parison, and can be appropriately selected according to the purpose. For example, extrusion blow molding, injection blow molding, stretch blow molding, multilayer blow molding, Examples include multi-dimensional blow molding. In the stretch blow molding, a gas is supplied after the parison is stretched, and examples thereof include sequential biaxial stretch blow molding and simultaneous biaxial stretch blow molding.
By the blow molding, a cavity is formed inside the molded body. The reason why cavities are formed inside the molded body is that the parison is pulled (stretched) by blow molding, so that fine destruction occurs inside the parison, and this forms a cavity to form a cavity. it is conceivable that.
The stretching speed of the parison in the blow molding is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 10 mm / min to 40,000 mm / min, and preferably 500 mm / min to 20,000 mm / min. More preferred is 1,000 mm / min to 10,000 mm / min.
If the stretching speed is less than 10 mm / min, voids may not be formed, and if it exceeds 40,000 mm / min, the parison may be easily broken during blowing.
The plane stretch ratio (longitudinal stretch ratio × transverse stretch ratio) of the parison in the blow molding is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 5 to 150 times.
10 times to 100 times is more preferable, and 15 times to 50 times is particularly preferable.
If the plane stretch ratio is less than 5 times, uneven thickness of the parison may not be eliminated, and if it exceeds 150 times, the parison may be easily broken during blowing.
There is no restriction | limiting in particular as said gas, According to the objective, it can select suitably, For example, air, nitrogen, etc. are mentioned.
The gas supply pressure is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0.2 Mpa to 20 Mpa, more preferably 0.4 Mpa to 10 Mpa, and particularly preferably 0.5 Mpa to 5 Mpa. .
If the supply pressure of the gas is less than 0.2 Mpa, the gas may not be blown at a sufficient speed, and if it exceeds 20 Mpa, the parison may be broken during blowing.

<Other processes>
There is no restriction | limiting in particular as said other process, According to the objective, it can select suitably, For example, a transfer process, a heating process, etc. are mentioned.

<< Transfer process >>
The transfer step is a step of blow-molding a parison in a mold and transferring the inner surface shape of the mold to the parison. In addition, it is preferable that the said transfer process is performed by the same blow molding as the said cavity formation process.

-Mold-
The mold is not particularly limited as long as it has an inner surface, and can be appropriately selected according to the purpose. Examples thereof include a mold 20 shown in FIGS. 1A to 2B.

-Transcription-
The transfer is performed by supplying gas and bringing the parison into close contact (following) with the inner surface of the mold.
There is no restriction | limiting in particular as said gas, According to the objective, it can select suitably, For example, air, nitrogen, etc. are mentioned.
The gas supply pressure is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0.2 Mpa to 20 Mpa, more preferably 0.4 Mpa to 10 Mpa, and particularly preferably 0.5 Mpa to 5 Mpa. .
When the gas supply pressure is less than 0.2 Mpa, the parison may not adhere (follow) the inner surface of the mold, and when it exceeds 20 Mpa, the parison may burst without being uniformly stretched.
The temperature of the mold is not particularly limited and may be appropriately selected depending on the intended purpose. It is preferably a parison softening point to a parison (melting point + 60 ° C.), and a parison softening point to a parison (melting point + 50). ° C) is more preferable, and the softening point of the parison to the melting point of the parison are particularly preferable.
When the temperature of the mold is lower than the softening point of the parison, the parison may not adhere (follow) to the inner surface of the mold, and when the temperature exceeds the (melting point + 60 ° C.) of the parison, It may not be maintained.

<< Heating process >>
The heating step is a step of heating the parison in the mold.
By this heating, the temperature of the parison in the mold can be raised, and the parison can be brought into close contact (following) with the inner surface of the mold. For example, the heating can be performed by a heating mechanism or the like provided in the mold.
The heating temperature in the heating step is not particularly limited and may be appropriately selected depending on the intended purpose. It is preferably from the glass transition temperature of the parison to the (melting point + 60) ° C. of the parison, and from the glass transition temperature of the parison to the parison. (Melting point + 30) ° C. is more preferable, and the glass transition temperature of the parison to the (melting point + 20) ° C. of the parison is particularly preferable.
If the heating temperature is lower than the glass transition temperature of the parison, the parison may not adhere (follow) to the inner surface of the mold, and if it exceeds the (melting point + 60) ° C. of the parison, the resin may flow. is there.
The heating rate in the heating step is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 1 ° C / min to 300 ° C / min, more preferably 2 ° C / min to 250 ° C / min. 5 ° C./min to 200 ° C./min is particularly preferable.
If the rate of temperature increase is less than 1 ° C./min, crystallization may proceed excessively at the time of temperature increase, and if it exceeds 300 ° C./min, the heating capability of the heating device increases. However, it may be difficult to incorporate a heating device into a series of blow molding systems, and it may be costly due to the need for highly accurate temperature control (control system).

Next, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the following examples.

Example 1
<Molding of PET bottle>
Polyethylene terephthalate resin pellets (manufactured by FUJIFILM Corporation, intrinsic viscosity (IV) = 0.91, glass transition temperature = 68 ° C.) are dried at 165 ° C. for 5 hours with a dehumidifying dryer, and the injection cylinder temperature is set at 270 ° C. From an injection molding machine set at 300 ° C., the product was injected into a parison mold whose temperature was adjusted to 76 ° C. (the parison cooling temperature was 76 ° C.), and a parison was produced in a molding cycle of 35 seconds. The opening part (end part) of the obtained parison was heated with an infrared heater and crystallized to impart heat resistance. Cross-sectional observation using an electron microscope (the sample was embedded in an epoxy resin and then cut out with LEICA ULTRACUT UCT (manufactured by Leica), cut into thin pieces, and observed with an electron microscope JEM-2010 (manufactured by JEOL Ltd.) ), It was found that the cavity starting particles were formed when the parison was cooled.
Next, the bottle was blow molded using a biaxial stretch blow molding apparatus. The parison was set in a molding machine, heated to 120 ° C. with an infrared heater, and then stretched and brought into close contact with compressed air at a pressure of 1.5 MPa in a blow molding mold adjusted to 170 ° C. to give a shape.
Thereafter, the bottle was solidified, cooled to 70 ° C. where handling was possible, and the bottle was taken out.

<Insulation evaluation>
A bottle with a capacity of 500 mL was molded, hot water at 75 ° C. was poured to the mouth, and the temperature was measured using a thermocouple installed at a position half the total height of the bottle inside the bottle.
The evaluation criteria are as follows, and the obtained results are shown in Table 1.
<< Evaluation criteria >>
The temperature difference with respect to the blank after 60 minutes is + 3 ° C. or less: ×
The temperature difference with respect to the blank after 60 minutes is greater than + 3 ° C. and not more than + 10 ° C .: Δ,
The temperature difference with respect to the blank after 60 minutes is larger than + 10 ° C. and not more than + 15 ° C .: The temperature difference with respect to the blank after 60 minutes is larger than + 15 ° C .: ◎
In addition, the said blank used the container blow-molded without forming a porous using the same material and the same metal mold as a porous molded object.

<High brightness evaluation>
A bottle with a capacity of 500 mL was molded, and a relatively flat portion centering on a height of 10 cm from the bottom of the container on the side of the container was cut into a 2 cm × 2 cm rectangle, and the light transmittance of this sample at a wavelength of 550 nm was measured.
The evaluation criteria are as follows, and the obtained results are shown in Table 1.
<< Evaluation criteria >>
Transmittance 60% or more ×
Transmittance 50% or more and less than 60%
Transmittance 40 to less than 50% ○ Transmittance less than 40% ◎

<Blow moldability evaluation>
The molded bottle is filled with water at 25 ° C. in an atmosphere at 25 ° C., and the capacity of the bottle is measured. Let the bottle capacity at this time be V1.
After draining the water, it is filled with hot water at 85 ° C., left for 10 minutes, drained, and left for 20 minutes with the bottle empty.
Thereafter, the bottle is filled again with water at 25 ° C., and the capacity of the bottle is measured. The bottle capacity at this time was set to V2.
If V2 / V1 is calculated and the change in capacity is 2% or less of the original capacity, it is acceptable (◎). If it exceeds 2% and 5% or less, it is acceptable (O). If it exceeds 5%, NG ( X). The obtained results are shown in Table 1.

(Example 2)
In Example 1, instead of setting the cooling temperature at the time of parison production to 76 ° C., a PET bottle was molded in the same manner as in Example 1 except that the cooling temperature at the time of parison production was 15 ° C. High brightness evaluation and blow moldability evaluation were performed. The obtained results are shown in Table 1. In addition, it became clear from the cross-sectional observation using the electron microscope that the cavity origin particle | grains were formed at the time of parison cooling.

(Example 3)
Instead of using polyethylene terephthalate resin pellets in Example 1, a fine particle-containing polymer in which silica having an average particle size of 0.1 μm was added to polyethylene terephthalate resin pellets was used. A PET bottle was molded in the same manner as in Example 1 except that the cooling temperature at the time of creating the parison was 88 ° C. instead of 76 ° C., and heat insulation evaluation, high brightness evaluation, and blow moldability evaluation were performed. The obtained results are shown in Table 1. In addition, it became clear from the cross-sectional observation using the electron microscope that the cavity origin particle | grains were formed at the time of parison cooling.

(Comparative Example 1)
In Example 1, instead of setting the cooling temperature at the time of parison production to 76 ° C, the PET bottle was molded in the same manner as in Example 1 except that the cooling temperature at the time of parison production was 101 ° C. High brightness evaluation and blow moldability evaluation were performed. In addition, it was found by cross-sectional observation using an electron microscope that no cavity starting particles were formed when the parison was cooled.

(Comparative Example 2)
In Example 1, instead of setting the cooling temperature at the time of parison production to 76 ° C., a PET bottle was molded in the same manner as in Example 1 except that the cooling temperature at the time of parison production was 80 ° C. High brightness evaluation and blow moldability evaluation were performed. In addition, it was found by cross-sectional observation using an electron microscope that no cavity starting particles were formed when the parison was cooled.

Example 4
In Example 1, instead of setting the cooling temperature at the time of parison production to 76 ° C, the PET bottle was molded in the same manner as in Example 1 except that the cooling temperature at the time of parison production was 68 ° C. High brightness evaluation and blow moldability evaluation were performed. In addition, it became clear from the cross-sectional observation using the electron microscope that the cavity origin particle | grains were formed at the time of parison cooling.

(Example 5)
In Example 1, instead of setting the cooling temperature at the time of parison production to 76 ° C, the PET bottle was molded in the same manner as in Example 1 except that the cooling temperature at the time of parison production was 64 ° C. High brightness evaluation and blow moldability evaluation were performed. In addition, it became clear from the cross-sectional observation using the electron microscope that the cavity origin particle | grains were formed at the time of parison cooling.

(Example 6)
In Example 1, instead of molding the PET bottle, the heat insulation evaluation, the high brightness evaluation, and the blow moldability evaluation were performed in the same manner as in Example 1 except that the PBT bottle was molded as follows. The obtained results are shown in Table 1.

<PBT bottle molding>
Polybutylene terephthalate resin pellets (manufactured by Polyplastic Co., 300FP) were dried at 105 ° C for 9 hours using a vacuum dryer, and then the temperature was adjusted to 5 ° C from an injection molding machine set at 245 ° C to 260 ° C. The sample was injected into the mold for parison (the parison cooling temperature was set to 5 ° C.), and a parison was produced in a molding cycle of 20 seconds.
The opening part (end part) of the obtained parison was heated with an infrared heater and crystallized to impart heat resistance. In addition, although it was transparent except the site | part crystallized and whitened of the opening part of a parison, as a result of cutting out a transparent site | part and performing X-ray analysis, it has a crystallinity of 15% and is a fine substance which permeate | transmits visible light. It was found that crystal nuclei (cavity starting particles) were formed.
Next, the bottle was blow molded using a biaxial stretch blow molding apparatus. The parison was set in a molding machine, heated to 45 ° C. with an infrared heater, and then stretched and brought into close contact with a compressed air with a pressure of 1.0 MPa in a blow molding mold adjusted to 115 ° C. to give a shape.
Thereafter, the bottle was solidified, cooled to 30 ° C. where handling was possible, and the bottle was taken out.

Since the porous molded body of the present invention contains cavities inside, it can be used, for example, as a bottle container that requires high heat insulation and high brightness.

1 Blow molding machine 10 Parison 20 Mold 20a Mold 20b Mold 30 Molded body

Claims (13)

A porous molded body characterized in that a parison containing at least one of a crystalline polymer and a fine particle-containing polymer is cooled to form cavity-origin particles and blow-molded to produce a molded body having a cavity inside. Manufacturing method. The method for producing a porous molded body according to claim 1, wherein the parison is cooled to a temperature not higher than 10 ° C higher than the glass transition temperature of the parison. The method for producing a porous molded body according to any one of claims 1 to 2, wherein the parison is cooled to below the glass transition temperature of the parison. The method for producing a porous molded body according to any one of claims 1 to 3, wherein the cooling rate of the parison at the time of forming the cavity starting particles is 5 ° C / min to 200 ° C / min. The method for producing a porous molded body according to any one of claims 1 to 4, wherein the stretching speed of the parison in blow molding is 10 mm / min to 40,000 mm / min. The method for producing a porous molded body according to any one of claims 1 to 5, wherein the crystalline polymer contains at least one of polyethylene terephthalate and polybutylene terephthalate. 7. The method for producing a porous molded body according to claim 1, wherein the volume average particle diameter of the fine particles is 0.01 μm to 10 μm. The method for producing a porous molded body according to any one of claims 1 to 7, wherein the fine particles are either an organic filler or an inorganic filler. The method for producing a porous molded body according to any one of claims 1 to 7, wherein the fine particles are resin fine particles incompatible with the fine particle-containing polymer. The method for producing a porous molded body according to any one of claims 1 to 9, further comprising: blow molding a parison in a mold and transferring the inner surface shape of the mold to the parison. The method for producing a porous molded body according to claim 10, further comprising heating the parison in the mold. The method for producing a porous molded body according to any one of claims 10 to 11, wherein the cavity formation and the transfer are performed by the same blow molding. A porous molded body produced by the method for producing a porous molded body according to claim 1.

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