JP5379980B2 - Cavity-containing resin molded body, method for producing the same, and image-receiving film or sheet for sublimation transfer recording material or thermal transfer recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a void-containing resin molded product with high thermal insulating properties and a method for manufacturing the same, moreover to provide an image-receiving film or sheet for a sublimation transfer or thermal transfer recording material, in which the molded product is contained. <P>SOLUTION: The void-containing resin molded product comprises a polymer composition including a polymer having crystallinity, in which long size voids are internally contained in a condition where longitudinal directions are oriented in one and the same direction. In an orthogonal cross-section to the orientation directions of the above voids in the above molded product, distances h(i) from respective centers to a surface of the above product are calculated, and an arithmetic mean value h(avg) of the above respective calculated distances h(i) fulfills a relation of following formula h(avg)&gt;T/100. When assuming that thermal conductivity of the above molded product is X(W/mK), and assuming that thermal conductivity of a polymer molded product in which a void is not contained comprising the same polymer composition as the polymer composition forming the above molded product with the same thickness as that of the above molded product, is Y(W/mK), an X/Y ratio is 0.27 or less in the void-containing resin molded product. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a void-containing resin molded article comprising a polymer composition containing a polymer having crystallinity, a method for producing the same, and an image receiving film or sheet for a sublimation transfer recording material or a thermal transfer recording material.

  The void-containing resin film or sheet is used as a member of image recording paper of a thermal transfer printer or a member for lighting of an electronic device because of its heat insulating property, cushioning property, light transmitting property (or light shielding property) and the like. It is being used.

In recent years, as the development of personal computers (PCs) and network environments has progressed, and electronic image storage devices such as digital cameras have become widespread, techniques for hard-copying images captured with these systems and products to sheets and the like are required. ing.
As the hard copy technology, there is a thermal transfer recording method (and a printer using the thermal transfer recording method) that is quiet when outputting various images, is easy to operate and maintain, and can be reduced in size and speed. It is becoming widespread.

  In the thermal transfer recording method, an ink ribbon formed by coating an ink layer containing a coloring component is superimposed on an image receiving sheet that is hard-copied (finally an image is formed), and then a thermal head is used. This is a printing (image formation) system in which an ink component on an ink ribbon is melted or sublimated by applying heat and transferred to the image receiving sheet side to form an image.

When the thermal transfer recording method was first applied, the image-receiving sheet material was a laminate of thin polypropylene synthetic paper and natural paper, or thick polypropylene synthetic paper as a base material, and a recording layer was formed on these surfaces. What was provided was used.
However, the polypropylene-based synthetic paper has surface smoothness and appropriate cushioning properties that cannot be obtained with natural paper, but has a problem that it is weak and easily wrinkled.

  Thereafter, image receiving sheet materials have been improved, and efforts to improve characteristics such as whiteness (improvement of vividness after printing), antistatic property (prevention of sticking), and improvement of difficulty in folding are continued. In addition, the quality of the print such as the print does not become faint or chipped, the “clearness” of the print, the “darkness” of the print, etc. are also emphasized.

  In recent years, in particular, from the viewpoint of downsizing, energy saving, and speeding up of printing (printing) devices, the head is in the direction of miniaturization, and as a result, the thermal energy given from the head to the image receiving sheet is small. It has become. Therefore, there is a need for an image receiving sheet that can easily melt and sublimate the ink components on the ink ribbon with a little heat energy and transfer it to the image receiving sheet side, and can form a stable image without blurring, chipping or unevenness. .

  Thus, a technique has been developed in which a polyester resin is used as the image receiving sheet material and a large amount of fine cavities are contained inside the image receiving sheet (see, for example, Patent Documents 1 to 3). This is because when the image receiving sheet contains fine cavities, the heat insulation effect of the image receiving sheet is enhanced by the air layer, and the thermal energy of the print head can be effectively printed.

  In the technique described in Patent Document 1, inorganic fine particles or the like are contained in a polyester resin film, and the inorganic fine particles and the resin interface are peeled off when the resin is stretched to form voids in the image receiving sheet. Is a technology for forming According to the technique described in Patent Document 1, the addition of inorganic fine particles makes the film white and the image becomes clear, and heat insulation can be obtained by forming cavities.

However, the technique described in Patent Document 1 requires advanced technology and equipment for fine dispersion, and it is necessary to add additives and to perform pretreatment of fine particles in order to suppress aggregation. Therefore, there is a problem that the manufacturing process becomes complicated and costs increase.
In addition, the finer the particles, the smaller the voids in the product and the better the heat insulating effect, which is preferable, but the aggregation of the fine particles not only causes printing unevenness but also on the surface of the image receiving sheet. Small protrusions were formed, which could damage the print head and eventually cause a device trouble.
In addition, when the concave portion is formed, there is a problem that the printing is missing or fading, which is difficult to solve easily. Further, when the foamed layer is developed to the vicinity of the surface of the image receiving sheet, there is a problem that the smoothness of the surface is impaired by foaming.

  The technique described in Patent Document 2 is a two-phase structure (resin (for example, polyester-based resin) having a two-phase structure by adding another resin that is incompatible with the resin (incompatible with the resin) and kneading the resin. For example, a sea-island structure) is formed, and a cavity is formed by peeling an interface between a resin, which is a main component at the time of resin film formation, and another resin added and kneaded therewith. At this time, by adjusting the size of the incompatible phase, the void can be easily controlled, and the performance of the image receiving sheet can be improved.

When an image receiving sheet is produced by the technique described in Patent Document 2, a mechanism is generally used in which a sea-island structure is formed and the interface is peeled off during film-forming stretching to generate voids. However, when manufacturing by such a mechanism, the desired two-phase structure is difficult to obtain because, for example, the island portion cannot be made sufficiently small, and as a result, the void cannot be made sufficiently small (control). There was a problem such as difficult).
Further, when the foamed layer is developed to the vicinity of the surface of the image receiving sheet, there is a problem that the smoothness of the surface is impaired by foaming. Further, when the void size is large, there is a problem that the printability is deteriorated or the high-class feeling is impaired.

  In addition, both of the techniques described in Patent Documents 1 and 2 are methods in which a different component is mixed in the main component and a void is expressed using it as a nucleus, so that the different component remains in the void. In some cases, the improvement in heat insulation was hindered. In addition, since it becomes a resin-inorganic system or a resin system of different types, the problem of difficulty in recycling is also becoming apparent.

  The technique described in Patent Document 3 is a technique in which a resin film is brought into contact with an inert gas under pressure, the resin film is impregnated with an inert gas, and stretched under atmospheric pressure to obtain a porous stretched resin film. It is. Since this technique uses gas as a cavity generation source, there is an advantage that problems such as heat insulation and recyclability can be easily avoided.

  However, in order to impregnate the film with an inert gas under pressure, a large-scale apparatus for processing the entire film under a high pressure exceeding several tens of atmospheres or 100 atmospheres is required, and a general melt film formation is required. -Compared with the stretching apparatus, there was a problem that the apparatus cost increased significantly. Further, since a large amount of inert gas is handled, equipment and measures for ensuring the safety of workers are required, and this also requires a considerable cost. In addition, in order to uniformly foam, a high degree of control is necessary, for example, it is necessary to make the conditions uniform in the manufacturing process.

Patent No. 30675557 JP 2005-281396 A JP 2006-8942 A

  An object of the present invention is to solve the conventional problems and achieve the following objects. That is, an object of the present invention is to provide a void-containing resin molded product having high heat insulation and a method for producing the same. Furthermore, an object of the present invention is to provide an image receiving film or sheet for a sublimation transfer recording material or a thermal transfer recording material, which contains the void-containing resin molded article and has excellent printing characteristics.

  In order to solve the above-mentioned problems, the present inventors have made extensive studies and as a result, obtained the following findings. That is, when a polymer film consisting only of PBT (polybutylene terephthalate), PHT (polyhexamethylene terephthalate), PBS (polybutylene succinate) or PP (polypropylene) is stretched at high speed, it becomes a void-containing film, and is stretched at high speed. The film (cavity-containing film) has a cavity-containing (multi-layer (tens of layers)) structure composed of a PBT layer (refractive index of about 1.5) and an air (cavity) layer (refractive index of 1), and a PHT layer (with a refractive index of about 1.5) and air (cavity) layer (refractive index 1) containing a cavity (multilayer (tens of layers)), PBS layer (refractive index about 1.5) and air (cavity) layer (refractive index 1) ) Structure containing multiple cavities (multilayer (several tens of layers)), or including a PP layer (refractive index of about 1.47) and air (cavity) layer (refractive index 1) (multiple layers (tens of layers)) ) Took the structure A finding say. Furthermore, it has been found that the void-containing resin film has excellent surface smoothness because no void is formed not only on the film surface but also at a predetermined distance from the film surface.

The present invention is based on the above findings by the present inventors, and means for solving the above problems are as follows. That is,
<1> A void-containing resin molded article comprising a polymer composition containing a polymer having crystallinity, and containing a long cavity therein in a state in which the length direction is oriented in one direction,
The ten cavities having the shortest distance from the center of the cavity to the surface of the cavity-containing resin molding in the cross section perpendicular to the orientation direction of the cavity in the cavity-containing resin molding, from each center to the cavity. The distance h (i) to the surface of the containing resin molding is calculated, and the calculated arithmetic mean value h (avg) of each of the distances h (i) is expressed by the following formula: h (avg)> T / 100 Meet relationships,
[However, T represents an arithmetic average value of thicknesses in the cross section, and the ten cavities are parallel to the straight line in parallel with the thickness direction, and parallel to the straight line and only 20 × T. It is selected from cavities existing in a region sandwiched by other straight lines located apart from each other. ]
And the thermal conductivity of the said cavity containing resin molding is set to X (W / mK), and it is the same thickness as the said cavity containing resin molding, and the same polymer composition as the polymer composition which comprises the said cavity containing resin molding It is a void-containing resin molded body characterized in that the X / Y ratio is 0.27 or less when the thermal conductivity of a polymer molded body which is made of a material and does not contain voids is Y (W / mK) .
<2> A void-containing resin molded article comprising a polymer composition containing a polymer having crystallinity and containing a long cavity therein in a state in which the length direction is oriented in one direction,
The ten cavities having the shortest distance from the center of the cavity to the surface of the cavity-containing resin molding in the cross section perpendicular to the orientation direction of the cavity in the cavity-containing resin molding, from each center to the cavity. The distance h (i) to the surface of the containing resin molding is calculated, and the calculated arithmetic mean value h (avg) of each of the distances h (i) is expressed by the following formula: h (avg)> T / 100 Meet relationships,
[However, T represents an arithmetic average value of thicknesses in the cross section, and the ten cavities are parallel to the straight line in parallel with the thickness direction, and parallel to the straight line and only 20 × T. It is selected from cavities existing in a region sandwiched by other straight lines located apart from each other. ]
And it is a cavity containing resin molding characterized by heat conductivity being 0.1 (W / mK) or less.
<3> The void content is 3% by volume or more and 50% by volume or less,
L / r ratio when the average length of the cavity in the thickness direction orthogonal to the orientation direction of the cavity is r (μm) and the average length of the cavity in the orientation direction of the cavity is L (μm), The void-containing resin molded product according to any one of <1> to <2>, which is 10 or more.
<4> The void-containing resin molded product according to any one of <1> to <3>, wherein the polymer having crystallinity is at least one of polyesters and polyolefins.
<5> A polymer molded body made of a polymer composition and containing no cavities at a speed of 10 to 36,000 mm / min, and
When the stretching temperature is T (° C) and the glass transition temperature of the polymer having crystallinity is Tg (° C),
(Tg-30) (° C.) ≦ T (° C.) ≦ (Tg + 50) (° C.)
The void-containing resin molded article according to any one of <1> to <4>, including a cavity formed by stretching at a stretching temperature T (° C.) in a range indicated by.
<6> A method for producing a void-containing resin molded product according to any one of <1> to <5>,
A polymer molded body comprising a polymer composition and containing no cavities at a speed of 10 to 36,000 mm / min, and
When the stretching temperature is T (° C) and the glass transition temperature of the polymer having crystallinity is Tg (° C),
(Tg-30) (° C.) ≦ T (° C.) ≦ (Tg + 50) (° C.)
It is a manufacturing method of the cavity containing resin molding including the process extended | stretched by extending | stretching temperature T (degreeC) of the range shown by these.
<7> An image-receiving film or sheet for a sublimation transfer recording material or a thermal transfer recording material containing the void-containing resin molded product according to any one of <1> to <5>.

  According to the present invention, various problems in the prior art can be solved, and a void-containing resin molded body having high heat insulation and a method for producing the same can be provided. Furthermore, according to the present invention, it is possible to provide an image receiving film or sheet for a sublimation transfer recording material or a thermal transfer recording material which contains the void-containing resin molded article and has excellent printing characteristics.

(Cavity-containing resin molding)
The void-containing resin molded product of the present invention is composed of a polymer composition and, if necessary, other components.
There is no restriction | limiting in particular as said "molded object", According to the objective, it can select suitably, For example, a film and a sheet | seat are mentioned.

[Polymer composition]
The polymer composition includes a polymer having crystallinity, and optionally includes other components that do not contribute to the development of cavities. The polymer composition is particularly preferably composed of only a polymer having crystallinity.

<Polymer having crystallinity>
In general, polymers are classified into crystalline polymers and amorphous (amorphous) polymers, but even polymers with crystallinity are not 100% crystalline, and long chain molecules in the molecular structure. Includes a crystalline region regularly arranged and an amorphous region which is not regularly arranged.
Therefore, as the polymer having crystallinity in the void-containing resin molded body of the present invention, it is sufficient that at least the crystalline region is included in the molecular structure, and the crystalline region and the amorphous region are mixed. Also good.

  There is no restriction | limiting in particular as said polymer which has crystallinity, According to the objective, it can select suitably, For example, high density polyethylene, polyolefins (for example, polypropylene, polyethylene, ethylene-vinyl acetate copolymer, ethylene- Vinyl alcohol copolymer, ethylene-cycloolefin copolymer, polybutene-1, poly-4-methylpentene-1, etc.), polyamides (PA) (for example, nylon-6), polyacetals (POM), polyesters (For example, PET, PEN, PTT, PBT, PPT, PHT, PBN, PES, PBS, etc.), syndiotactic polystyrene (SPS), polyphenylene sulfides (PPS), polyether ether ketones (PEEK), liquid crystal polymer (LCP), fluororesin And the like. Among them, polyesters, syndiotactic polystyrene (SPS), and liquid crystal polymers (LCP) are preferable from the viewpoint of mechanical strength and production, and polyesters are more preferable. Two or more of these polymers may be blended or copolymerized.

There is no restriction | limiting in particular as melt viscosity of the polymer which has the said crystallinity, Although it can select suitably according to the objective, 50-700 Pa.s is preferable, 70-500 Pa.s is more preferable, 80-300 Pa.s s is more preferable. When the melt viscosity is 50 to 700 Pa · s, it is preferable in that the shape of the melt film discharged from the die head during melt film formation is stable and uniform film formation is facilitated. In addition, when the melt viscosity is 50 to 700 Pa · s, the viscosity at the time of melt film formation becomes appropriate and the extrusion becomes easy, or the melt film at the time of film formation is leveled to reduce unevenness. preferable.
Here, the melt viscosity can be measured by a plate type rheometer or a capillary rheometer.

There is no restriction | limiting in particular as intrinsic viscosity (IV) of the polymer which has the said crystallinity, Although it can select suitably according to the objective, 0.4-1.2 are preferable and 0.6-1.0 are More preferred is 0.7 to 0.9. When the IV is 0.4 to 1.2, the strength of the formed film is increased, and this is preferable in that the film can be efficiently stretched.
Here, the IV can be measured by an Ubbelohde viscometer.

There is no restriction | limiting in particular as melting | fusing point (Tm) of the polymer which has the said crystallinity, Although it can select suitably according to the objective, 100-350 degreeC is preferable, 100-300 degreeC is more preferable, 100-260 degreeC Is more preferable. The melting point of 40 to 350 ° C. is preferable in that the shape can be easily maintained in a temperature range expected for normal use, and even if a special technique required for processing at a high temperature is not particularly used. It is preferable at the point which can form a stable film.
Here, the melting point can be measured by a differential thermal analyzer (DSC).

-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. Therefore, as the polyester resin suitable as the polymer having the crystallinity, the exemplified PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PTT (polytrimethylene terephthalate), PBT (polybutylene terephthalate), Not only PPT (polypentamethylene terephthalate), PHT (polyhexamethylene terephthalate), PBN (polybutylene naphthalate), PES (polyethylene succinate), PBS (polybutylene succinate), but also a dicarboxylic acid component and a diol component All polymer compounds obtained by polycondensation reaction are included.

  The dicarboxylic acid component is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, alicyclic dicarboxylic acids, oxycarboxylic acids, and polyfunctional acids. Among them, aromatic dicarboxylic acids are preferable.

  Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, diphenyldicarboxylic acid, diphenylsulfonedicarboxylic acid, naphthalenedicarboxylic acid, diphenoxyethanedicarboxylic acid, and 5-sodium sulfoisophthalic acid. Acid, diphenyldicarboxylic acid, and naphthalenedicarboxylic acid are preferable, and terephthalic acid, diphenyldicarboxylic acid, and naphthalenedicarboxylic acid are more preferable.

  Examples of the aliphatic dicarboxylic acid include oxalic acid, succinic acid, eicoic acid, adipic acid, sebacic acid, dimer acid, dodecanedioic acid, maleic acid, and fumaric acid. Examples of the alicyclic dicarboxylic acid include cyclohexane dicarboxylic acid. Examples of the oxycarboxylic acid include p-oxybenzoic acid. Examples of the polyfunctional acid include trimellitic acid and pyromellitic acid. Among the aliphatic dicarboxylic acids and alicyclic dicarboxylic acids, succinic acid, adipic acid, and cyclohexanedicarboxylic acid are preferable, and succinic acid and adipic acid are more preferable.

  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. Group diols are preferred.

  Examples of the aliphatic diol include ethylene glycol, propane diol, butane diol, pentane diol, hexane diol, neopentyl glycol, and triethylene glycol. Among them, propane diol, butane diol, pentane diol, and hexane diol are exemplified. Particularly preferred. Examples of the alicyclic diol include cyclohexanedimethanol. Examples of the aromatic diol include bisphenol A and bisphenol S.

  There is no restriction | limiting in particular as melt viscosity of the said polyester resin, Although it can select suitably according to the objective, 50-700 Pa.s is preferable, 70-500 Pa.s is more preferable, 80-300 Pa.s is further preferable. When the melt viscosity is higher, voids are more likely to be generated during stretching. However, when the melt viscosity is 50 to 700 Pa · s, it is easy to extrude during film formation, and the resin flow is stable and retention is less likely to occur. It is preferable in that the quality is stabilized. Further, the melt viscosity of 50 to 700 Pa · s is preferable in that the stretching tension is appropriately maintained at the time of stretching, and the film is easily stretched uniformly and is not easily broken. In addition, when the melt viscosity is 50 to 700 Pa · s, it is easy to maintain the form of the melt film discharged from the die head during film formation, and it is possible to stably form the product or to prevent the product from being damaged. , Which is preferable in terms of enhancing physical properties.

  There is no restriction | limiting in particular as intrinsic viscosity (IV) of the said polyester resin, Although it can select suitably according to the objective, 0.4-1.2 are preferable, 0.6-1.0 are more preferable, More preferred is 0.7 to 0.9. When the IV is larger, voids are more likely to be generated during stretching. However, when the IV is 0.4 to 1.2, extrusion is easier during film formation, and the resin flow is stable and retention is less likely to occur. It is preferable in that the quality is stabilized. Furthermore, when the IV is 0.4 to 1.2, the stretching tension is appropriately maintained at the time of stretching, and therefore, it is easy to stretch uniformly and it is preferable in that a load is not easily applied to the apparatus. In addition, when the IV is 0.4 to 1.2, it is preferable in that the product is hardly damaged and the physical properties are increased.

  There is no restriction | limiting in particular as melting | fusing point of the said polyester resin, Although it can select suitably according to the objective, From viewpoints, such as heat resistance and film forming property, 150-300 degreeC is preferable and 160-270 degreeC is more preferable. .

  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 when the film is formed or melted. It is preferable in that the physical properties are enhanced during extrusion and the extrusion becomes easy.

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

-Polyolefin resin-
The polyolefins (hereinafter referred to as “polyolefin resins”) mean polymers obtained by polymerizing α-olefins based on ethylene. As the polyolefin resin suitable as the polymer having the crystallinity, as described above, for example, polypropylene, polyethylene, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-cycloolefin copolymer, Polybutene-1, poly-4-methylpentene-1, etc. are mentioned. Among these, polyethylene and polypropylene are more preferable, and polypropylene is particularly preferable.

  There is no restriction | limiting in particular as melt viscosity of the said polyolefin resin, Although it can select suitably according to the objective, 50-700 Pa.s is preferable, 70-500 Pa.s is more preferable, 80-300 Pa.s is further preferable. When the melt viscosity is higher, voids are more likely to be generated during stretching. However, when the melt viscosity is 50 to 700 Pa · s, it is easy to extrude during film formation, and the resin flow is stable and retention is less likely to occur. It is preferable in that the quality is stabilized. Further, the melt viscosity of 50 to 700 Pa · s is preferable in that the stretching tension is appropriately maintained at the time of stretching, and the film is easily stretched uniformly and is not easily broken. In addition, when the melt viscosity is 50 to 700 Pa · s, it is easy to maintain the form of the melt film discharged from the die head during film formation, and it is possible to stably form the product or to prevent the product from being damaged. , Which is preferable in terms of enhancing physical properties.

Further, as the polyolefin resin, those copolymerized with different kinds of resins may be used, or 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 when the film is formed or melted. It is preferable in that the physical properties are enhanced during extrusion and the extrusion becomes easy.
In addition, for the purpose of improving the flow characteristics of the polyolefin resin, controlling the light transmittance, and improving the adhesion with the coating solution, a resin other than the polyolefin resin may be added to the polyolefin resin.

  As described above, the void-containing resin molded body of the present invention forms voids in a simple process even without adding a void forming agent such as inorganic fine particles or incompatible resins added in the prior art. be able to. Furthermore, no special equipment for dissolving the inert gas in the resin in advance is required. The method for producing the void-containing resin molded product will be described later.

  Here, the void-containing resin molded body may contain other components as necessary as long as it does not contribute to the development of the void. Examples of the other components include a heat resistance stabilizer, an antioxidant, an organic lubricant, a nucleating agent, a dye, a pigment, a dispersant, a coupling agent, and a fluorescent brightening agent. Whether or not the other component contributed to the development of the cavity can be determined by whether or not a component other than the polymer having crystallinity (for example, each component described later) is detected in the cavity or at the interface portion of the cavity. .

There is no restriction | limiting in particular as said antioxidant, According to the objective, it can select suitably, For example, you may add well-known hindered phenols. Examples of the hindered phenols include antioxidants commercially available under trade names such as Irganox 1010, Similarizer BHT, and Similarizer GA-80.
Further, the antioxidant can be used as a primary antioxidant and further combined with a secondary antioxidant. Examples of the secondary antioxidant include antioxidants commercially available under trade names such as Sumilizer TPL-R, Sumilizer TPM, Sumilizer TP-D, and the like.

  The fluorescent whitening agent is not particularly limited and may be appropriately selected depending on the intended purpose. For example, commercially available products with names such as Ubitech, OB-1, TBO, Keicoal, Kayalite, Leukopua, EGM, etc. Can be used. In addition, the said fluorescent whitening agent may be used individually by 1 type, and may use 2 or more types together. By adding the fluorescent whitening agent in this way, it is possible to give a brighter and more bluish whiteness and to have a high-class feeling.

In the void-containing resin molded body of the present invention, since it is possible to form a cavity without using a component that contributes to the development of the cavity, a cavity forming agent such as a thermoplastic resin or inorganic particles is formed in the cavity portion. Not included. That is, since only air with low thermal conductivity exists mainly in the hollow portion of the void-containing resin molded body of the present invention, the thermal conductivity of the film is greatly reduced. Such properties indicate that the void-containing resin molded product of the present invention can be suitably used as an image receiving sheet excellent in printing (printing) characteristics.
On the other hand, in the conventional void-containing resin molded body, since a cavity cannot be formed unless a cavity forming agent is used, the cavity portion contains the cavity forming agent. In the cavity part of the conventional cavity-containing resin molded body, the cavity forming agent occupies a part of the cavity to be originally opened and becomes a heat path from the film surface to the back surface (exists in a bridge shape), or the cavity When the forming agent itself has a high thermal conductivity, the cavity forming agent promotes heat conduction from the front surface to the back surface of the film or promotes heat conduction in the polymer layer.

<Cavity>
The void-containing resin molded body of the present invention contains long cavities inside with the length direction oriented in one direction, and is characterized by the void content and the aspect ratio of the voids.
The cavity means a vacuum domain or a gas phase domain existing inside the resin molded body.

The void content means the total volume of the contained cavities relative to the sum of the total volume of the solid phase portion of the resin molded body and the total volume of the contained cavities.
The void content is not particularly limited as long as the effects of the present invention are not impaired, and can be appropriately selected according to the purpose, preferably 3% by volume or more and 50% by volume or less, and 5 to 40% by volume. More preferred is 10 to 30% by volume.
Here, the void content can be calculated based on the specific gravity by measuring the specific gravity.
Specifically, the void content can be obtained by the following equation (1).
Cavity content (%) = {1- (Density of cavity-containing resin molding after stretching) / (Density of polymer molding before stretching)} (1)

The aspect ratio refers to an average length of the cavity in the thickness direction orthogonal to the orientation direction of the cavity, r (μm), and an average length of the cavity in the orientation direction of the cavity, L (μm). L / r ratio is meant.
The aspect ratio is not particularly limited as long as the effects of the present invention are not impaired, and can be appropriately selected according to the purpose. The aspect ratio is preferably 10 or more, more preferably 15 or more, and still more preferably 20 or more. .

  2A to 2C are diagrams for specifically explaining the aspect ratio, in which FIG. 2A is a perspective view of the void-containing resin molded body, and FIG. 2B is A of the void-containing resin molded body in FIG. 2A. -A 'sectional drawing, FIG. 2C is BB' sectional drawing of the cavity containing resin molding in FIG. 2A.

  In the manufacturing process of the void-containing resin molded body, the void is usually oriented along the first stretching direction. Therefore, the “average length of the cavity (r (μm)) in the thickness direction perpendicular to the orientation direction of the cavity” is perpendicular to the surface 1a of the cavity-containing resin molded body 1 and in the first stretching direction. This corresponds to the average thickness r (see FIG. 2B) of the cavity 100 in a cross section at right angles (cross section AA ′ in FIG. 2A). The “average length (L (μm)) of the cavity in the orientation direction of the cavity” is a cross section perpendicular to the surface of the cavity-containing resin molded body and parallel to the first stretching direction (FIG. This corresponds to the average length L (see FIG. 2C) of the cavity 100 in the section BB ′ in 2A.

In addition, said 1st extending | stretching direction shows the extending direction of 1 axis | shaft, when extending | stretching is only 1 axis | shaft. Usually, since longitudinal stretching is performed along the direction in which the molded body flows during production, this longitudinal stretching direction corresponds to the first stretching direction.
Moreover, when extending | stretching is biaxial or more, at least 1 direction is shown among the extending directions aiming at cavity formation. Usually, even in stretching with two or more axes, longitudinal stretching is performed along the flow direction of the molded body during production, and a cavity can be formed by this longitudinal stretching. It corresponds to the first stretching direction.

  Here, the average length (r (μm)) of the cavities in the thickness direction orthogonal to the orientation direction of the cavities can be measured by an image of an optical microscope or an electron microscope. Similarly, the average length (L (μm)) of the cavities in the alignment direction of the cavities can be measured by an image of an optical microscope or an electron microscope.

  Thus, the said cavity containing resin molding has various outstanding characteristics, for example in heat conductivity, by containing the said cavity. In other words, characteristics such as thermal conductivity can be adjusted by changing the mode of the cavity contained in the cavity-containing resin molded body.

-Thermal conductivity-
The thermal conductivity of the void-containing resin molded body is preferably 0.1 (W / mK) or less, more preferably 0.09 (W / mK) or less, and 0.08 (W / mK). mK) or less is more preferable.

Moreover, the suitable thermal conductivity of the said void containing resin molding can also be prescribed | regulated as a relative value. That is, the thermal conductivity of the void-containing resin molding is X (W / mK), and the same polymer composition as the polymer composition constituting the void-containing resin molding with the same thickness as the void-containing resin molding. The X / Y ratio is preferably 0.27 or less, when the thermal conductivity of a polymer molded body made of a product and containing no voids is Y (W / mK), and is preferably 0.2 or less. More preferably, it is still more preferably 0.15 or less.
Here, the thermal conductivity can be calculated by a product of measured values of thermal diffusivity, specific heat, and density. The thermal diffusivity can be generally measured by a laser flash method (for example, TC-7000 (manufactured by Vacuum Riko Co., Ltd.)). The specific heat can be measured by DSC according to the method described in JIS K7123. The density can be calculated by measuring the mass of a certain area and its thickness.

Furthermore, the void-containing resin molded body does not contain inorganic fine particles, incompatible resin, inert gas, or the like, which have been added in the prior art, while containing the voids. Therefore, it has excellent surface smoothness.
The surface smoothness of the void-containing resin molded body is not particularly limited and may be appropriately selected depending on the intended purpose. Ra = 0.3 μm or less is preferable, Ra = 0.25 μm or less is more preferable, and Ra = 0.1 μm or less is particularly preferable.

Furthermore, the cavity-containing resin molded body is characterized in that no cavity is formed not only on the surface of the molded body but also at a predetermined distance from the surface of the molded body.
That is, in the cross section orthogonal to the orientation direction of the cavity in the cavity-containing resin molded body, the 10 cavities having the shortest distance from the center of the cavity to the surface of the cavity-containing resin molded body are measured from each center. A distance h (i) to the surface of the void-containing resin molded body is calculated, and an arithmetic average value h (avg) of each calculated distance h (i) is expressed by the following formula: h (avg)> T / 100 Satisfy the relationship.
However, T represents the arithmetic mean value of the thickness in the cross section, and the ten cavities are separated from any one straight line parallel to the thickness direction by 20 × T parallel to the one straight line. Are selected from cavities existing in a region sandwiched by other straight lines positioned at the same time.

The “center of the cavity” means the center when the cross-sectional shape of the cavity in the cross section is a perfect circle, and is arbitrarily set by, for example, the maximum square center method in the case of other shapes. The center of the circle that minimizes the sum of squares of the deviation from the reference circle is determined, and this is set as the center of the cavity.
The “surface of the void-containing resin molded body” means the outermost surface of the void-containing resin molded body in the thickness direction. Usually, it means the upper surface when the void-containing resin molded body is placed.

Specifically, a cross section perpendicular to the surface of the void-containing resin molded body and perpendicular to the longitudinal stretching direction (see FIG. 2D) is examined at an appropriate magnification of 300 to 3000 times using a scanning electron microscope. Then, a cross-sectional photograph is taken. In the cross-sectional photograph, an arithmetic average value T of the thickness is calculated. As the arithmetic average value T of the thickness, a thickness measured using a long range contact displacement meter or the like may be used. In addition, FILM THICKNESS TESTER KG601B manufactured by Anritsu can be used for measuring the thickness.
Next, an arbitrary straight line parallel to the thickness direction is drawn in the cross-sectional photograph, and another straight line that is parallel to the single straight line and separated by 20 × T is drawn.
Then, in each cavity in the cross-sectional photograph, the center of a circle that minimizes the sum of squares of deviations from the reference circle arbitrarily set by the maximum square center method is determined, and this is set as the center of the cavity.
Then, in the region sandwiched between the one straight line and the other straight line, ten cavities having the shortest distance from the center of the cavity to the surface of the cavity-containing resin molded body are selected. The above-mentioned “distance from the center of the cavity to the surface of the cavity-containing resin molded body” means that when drawing a circle centered on the “center of the cavity”, the radius of the circle to be drawn is sequentially increased, The radius of the circle when it first contacts the surface of the void-containing resin molded body.
Then, for the 10 selected cavities, a distance h (i) from each center to the surface of the cavity-containing resin molded body is calculated, and an arithmetic average value h (avg) of each calculated distance h (i) Is calculated by the following equation (2).
h (avg) = (Σh (i)) / 10 (2)
The “distance h (i) from each center to the surface of the cavity-containing resin molded body” is to be accurately measured when the cavity-containing resin molded body is curved or stressed. Therefore, it is preferable that the measurement is performed in a state where it is placed in a flat shape.
The void-containing resin molded body has excellent surface smoothness since the void is not formed near the surface of the void-containing resin molded body while containing the void.

(Method for producing void-containing resin molding)
The method for producing the void-containing resin molded body includes at least a stretching process for stretching the polymer molded body, and further includes other processes such as a film forming process as necessary.
In addition, the said polymer molded object consists of a polymer composition containing the polymer which has the said crystallinity, and shows the thing which does not contain a cavity especially, for example, a polymer film, a polymer sheet, etc. are mentioned.

-Stretching process-
In the stretching step, the polymer molded body is stretched at least uniaxially. And by the said extending process, while a polymer molded object is extended | stretched, the cavity orientated along the 1st extending | stretching direction is formed in the inside, and a cavity containing resin molded object is obtained.

The reason why the cavity is formed by stretching is that the polymer having at least one crystallinity constituting the polymer molded body forms a minute crystal region or a minute region having regularity at a certain level of molecules. It is considered that a cavity is formed by exfoliating and stretching in such a way that the resin between phases including a crystal or microstructure region that is difficult to stretch during stretching is torn. It is done.
Such void formation by stretching is possible not only when there is only one kind of polymer having crystallinity but also when two or more kinds of polymers having crystallinity are blended or copolymerized. is there.

  The stretching method is not particularly limited as long as the effects of the present invention are not impaired, and examples thereof include uniaxial stretching, sequential biaxial stretching, and simultaneous biaxial stretching. It is preferable that longitudinal stretching is performed along the direction in which the molded body flows.

In general, in the longitudinal stretching, the number of longitudinal stretching stages and the stretching speed can be adjusted by the combination of rolls and the speed difference between the rolls.
The number of stages of the longitudinal stretching is not particularly limited as long as it is one or more, but it can be stretched more than two stages in terms of more stable and high-speed stretching and production yield and machine restrictions. It is preferable to do. Further, longitudinal stretching in two or more stages is advantageous in that a cavity can be formed by stretching in the second stage after confirming the occurrence of necking in the first stage.
In addition, the stretching conditions (for example, the stretching speed and the stretching temperature) in the second and subsequent stages may be the same as or different from the first stage.

-Stretching speed-
There is no restriction | limiting in particular as long as the effect of this invention is not impaired as the extending | stretching speed of the said longitudinal stretch, Although it can select suitably according to the objective, 10-36,000 mm / min is preferable, 800-24,000 mm / Min is more preferable, and 1200 to 12,000 mm / min is even more preferable. When the stretching speed is 10 mm / min or more, it is preferable in that sufficient necking can be easily expressed. Further, when the stretching speed is 36,000 mm / min or less, uniform stretching is facilitated, the resin is not easily broken, and the cost is reduced without requiring a large stretching apparatus for high-speed stretching. It is preferable in that it can be performed. Therefore, when the stretching speed is 10 to 36,000 mm / min, sufficient necking is easily developed, uniform stretching is facilitated, the resin is difficult to break, and a large size intended for high-speed stretching. It is preferable at the point which can reduce cost, without requiring an extending | stretching apparatus.

  More specifically, the stretching speed in the case of one-stage stretching is preferably 1,000 to 36,000 mm / min, more preferably 1,100 to 24,000 mm / min, and 1,200 to 12,000 mm / min. Min is more preferable.

  In the case of two-stage stretching, it is preferable that the first-stage stretching is a preliminary stretching whose main purpose is to develop necking. The stretching speed of the preliminary stretching is preferably 10 to 300 mm / min, more preferably 40 to 220 mm / min, and still more preferably 70 to 150 mm / min.

  In the two-stage stretching, it is preferable that the second-stage stretching speed after the necking is expressed by the preliminary stretching (first-stage stretching) is changed from the preliminary stretching speed. The stretching speed of the second stage after causing necking by the preliminary stretching is preferably 600 to 36,000 mm / min, more preferably 800 to 24,000 mm / min, and 1,200 to 15,000 mm. / Min is more preferable.

There is no restriction | limiting in particular as a measuring method of the said extending | stretching speed, Although it can select suitably from well-known methods, For example, it can measure with the following method.
In the case of the batch type, the movement speed when the clamp holding the end of the polymer molded body moves in the stretching direction, that is, the movement distance of the clamp / the time (mm / min) required for the movement of the clamp. The stretching speed is used. The stretching speed defined in the present embodiment is the stretching speed in the batch type unless otherwise specified.

  Further, when the polymer molded body is stretched due to a difference in the surface speed of the nip roll when the polymer molded body passes through two pairs (or more) of nip rolls (generally referred to as “Roll to Roll stretching”). In the case, the gripping position of the polymer molded body is fixed by a nip roll and does not move. Therefore, in the case of the above Roll to Roll stretching, the stretch ratio is the stretched ratio / the time required for stretching (% / min). The nip roll corresponds to the roll 15a in FIG.

  The stretching speed in the batch method and the stretching speed in the Roll-to-Roll stretching are the length before stretching (mm) and the length after stretching (mm) of the polymer molded body in any stretching method. If they are measured, they can be converted into each other. Table 1 shows an example in which the stretching speed in the batch method is converted into the stretching speed in Roll to Roll stretching.

--Extension temperature--
The temperature during stretching is not particularly limited and can be appropriately selected according to the purpose.
When the stretching temperature is T (° C) and the glass transition temperature of the polymer having crystallinity is Tg (° C),
(Tg-30) (° C.) ≦ T (° C.) ≦ (Tg + 50) (° C.)
It is preferable to stretch at a stretching temperature T (° C.) in the range indicated by
(Tg-25) (° C.) ≦ T (° C.) ≦ (Tg + 50) (° C.)
It is more preferable to stretch at a stretching temperature T (° C.) in the range indicated by
(Tg-20) (° C.) ≦ T (° C.) ≦ (Tg + 50) (° C.)
More preferably, the film is stretched at a stretching temperature T (° C.) in the range indicated by.

  In general, the higher the stretching temperature (° C.), the lower the stretching tension and the easier the stretching, but the stretching temperature (° C.) is {glass transition temperature (Tg) −30} ° C. or higher, {glass transition temperature ( Tg) +50} ° C. or lower is preferable in that the void content increases, the aspect ratio tends to be 10 or more, and the voids are sufficiently developed.

  Here, the stretching temperature T (° C.) can be measured with a non-contact thermometer. The glass transition temperature Tg (° C.) can be measured by a differential thermal analyzer (DSC).

In the stretching step, lateral stretching may or may not be performed as long as it does not hinder the appearance of cavities. In the case of lateral stretching, the film may be relaxed or heat-treated using a lateral stretching process.
Further, the stretched void-containing resin molded body may be further subjected to a treatment such as heat shrinkage by applying heat or application of tension for the purpose of shape stabilization.

There is no restriction | limiting in particular as a manufacturing method of the said polymer molded object, According to the objective, it can select suitably, For example, when the polymer which has crystallinity is a polyester resin or polyolefin resin, a melt film forming method is used. It can manufacture suitably.
Moreover, the polymer molded body may be produced independently of the stretching step or continuously.

Drawing 1 is a figure showing an example of a manufacturing method of a void content resin fabrication object of the present invention, and is a flow figure of a biaxially stretched film manufacturing device. The biaxially stretched film manufacturing apparatus shown in FIG. 1 is a film manufacturing apparatus that performs Roll to Roll stretching.
As shown in FIG. 1, a raw material resin (polymer composition) 11 is melted in an extruder 12 (a twin screw extruder or a single screw extruder is used depending on the raw material shape and production scale). After being kneaded, the T-die 13 is discharged into a soft plate shape (film or sheet shape).
Next, the discharged film or sheet F is cooled and solidified by the casting roll 14 to form a film. The formed film or sheet F (corresponding to “polymer molded body”) is sent to the longitudinal stretching machine 15.
And the film or sheet | seat F formed into a film is again heated within the longitudinal stretch machine 15, and is stretched | stretched longitudinally between the rolls 15a from which speed differs. By this longitudinal stretching, a cavity is formed in the film or sheet F along the stretching direction. Then, the film or sheet F in which the cavity is formed is gripped at both ends by the left and right clips 16a of the transverse stretching machine 16, and is stretched laterally while being sent to the winder side (not shown). The resin molded body 1 is obtained. In addition, in the said process, you may use the film or sheet | seat F which performed only the longitudinal stretch as the cavity formation resin molding 1 without providing to the horizontal stretching machine 16. FIG.

<Application>
Since the void-containing resin molded product of the present invention has high surface smoothness and has excellent heat insulating properties due to the inclusion of the voids, the image receiving device can be used for sublimation transfer recording materials or thermal transfer recording materials. It is optimal as a film material or an image receiving sheet material, and can be used as various heat insulating materials.

(Image-receiving film or sheet for sublimation transfer recording material or thermal transfer recording material)
In the image-receiving film or sheet for sublimation transfer recording material or thermal transfer recording material, a dye receiving layer (receiving layer) is formed on a support, and a base layer is formed between the receiving layer and the support. It is preferable. Examples of the base layer include a white background adjustment layer, a charge adjustment layer, an adhesive layer, and a primer layer. Moreover, it is preferable that the heat insulation layer is formed between the base layer and the support body. The void-containing resin molded body (void-containing resin film or sheet) of the present invention is preferably used for the heat insulating layer. Each layer between the support and the receiving layer is simply referred to as an “intermediate layer”, and the “intermediate layer” includes the underlayer and the heat insulating layer described above. The image-receiving film or sheet for sublimation transfer recording material or thermal transfer recording material of the present invention contains at least one receptor layer and at least one intermediate layer. It is preferable that a curl adjusting layer, a writing layer, and a charge adjusting layer are formed on the back side of the support.

  JP, 2007-30275, A etc. can be referred to for details about composition, a constituent, and a manufacturing method of layers, such as the above-mentioned support, a receiving layer, a foundation layer.

  Examples of the method for forming each layer include gravure reverse coating, reverse (roll) coating, gravure coating, knife coating, blade coating, air knife coating, bill blade coating, rotating screen coating, rod coating, bar coating, and roll coating. , Gate roll coat, brush coat, spray coat, curtain coat, bead coat, slot orifice coat, die slot coat, die coat, extrusion coat and the like.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the following examples are not intended to limit the present invention, and modifications may be made without departing from the spirit described above and below. Included in the technical scope.

This example prepares resin films (Examples 1 to 13) that satisfy the requirements of the present invention (containing voids) and resin films that do not satisfy the requirements (Comparative Examples 1 to 5), and evaluate their characteristics This is an example.
In this example, the polymer film was all stretched batchwise.

<Example 1>
PBT1 (polybutylene terephthalate 100% resin) with IV = 0.72 was extruded from a T-die using a melt extruder at 245 ° C. and solidified with a casting drum to obtain a polymer film having a thickness of about 120 μm. This polymer film was uniaxially stretched (longitudinal stretching).
Specifically, in a heated atmosphere of 40 ° C., after uniaxial stretching at a speed of 100 mm / min and confirming that necking has occurred, it is further performed in the same direction as the beginning at a speed of 6,000 mm / min. Uniaxial stretching was performed.

<Example 2>
In Example 1, the stretching temperature was set to 30 ° C., the thickness of the polymer film was set to about 50 μm, and the second stage longitudinal stretching speed was stretched at 12,000 mm / min instead of 6,000 mm / min. A resin film was produced in the same manner as in Example 1 except that.

<Example 3>
PBT1 (polybutylene terephthalate 100% resin) with IV = 0.72 was extruded from a T-die using a melt extruder at 245 ° C. and solidified with a casting drum to obtain a polymer film having a thickness of about 100 μm. This polymer film was uniaxially stretched (longitudinal stretching).
Specifically, it was uniaxially stretched at a speed of 2,400 mm / min in a heated atmosphere at 40 ° C.

<Example 4>
In Example 3, a resin film was produced in the same manner as in Example 3 except that the longitudinal stretching speed of the first stage was changed at 8,000 mm / min instead of 2,400 mm / min.

<Example 5>
In Example 3, a resin film was produced in the same manner as in Example 3 except that the longitudinal stretching speed of the first stage was changed at 11,000 mm / min instead of 2,400 mm / min.

<Example 6>
PBT1 used in Example 1 and PET (made by FUJIFILM Corporation) with IV = 0.67 were mixed at PBT1: PET = 90: 10 at a temperature of 285 ° C. using a melt extruder. And polymerized with a casting drum to obtain a polymer film having a thickness of about 55 μm. This polymer film was uniaxially stretched (longitudinal stretching).
Specifically, in a heated atmosphere at 60 ° C., after uniaxially stretching at a speed of 100 mm / min and confirming that necking has occurred, further in the same direction as the beginning at a speed of 4,000 mm / min. Uniaxial stretching was performed.

<Example 7>
PBT1 used in Example 1 and PET having IV = 0.67 (manufactured by FUJIFILM Corporation) mixed with PBT1: PET = 95: 5 were T-die at 285 ° C. using a melt extruder. And solidified with a casting drum to obtain a polymer film having a thickness of about 100 μm. This polymer film was uniaxially stretched (longitudinal stretching).
Specifically, it was uniaxially stretched at a rate of 5,600 mm / min in a heated atmosphere at 60 ° C.

<Example 8>
PBT1 used in Example 1 and PET (produced by FUJIFILM Corporation) with IV = 0.67 were mixed at PBT1: PET = 80: 20 at a temperature of 285 ° C. using a melt extruder. And solidified with a casting drum to obtain a polymer film having a thickness of about 100 μm. This polymer film was uniaxially stretched (longitudinal stretching).
Specifically, in a heated atmosphere at 70 ° C., after uniaxially stretching at a speed of 100 mm / min and confirming that necking has occurred, further in the same direction as the beginning at a speed of 5,000 mm / min. Uniaxial stretching was performed.

<Example 9>
PBT2 (polybutylene terephthalate 100% resin) with IV = 0.86 was extruded from a T die using a melt extruder at 250 ° C. and solidified with a casting drum to obtain a polymer film having a thickness of about 80 μm. This polymer film was uniaxially stretched (longitudinal stretching).
Specifically, it was uniaxially stretched in one step at a speed of 4,800 mm / min in a heated atmosphere at 40 ° C.

<Example 10>
PBS (polybutylene succinate 100% resin) with IV = 0.67 was extruded from a T-die using a melt extruder at 175 ° C. and solidified with a casting drum to obtain a polymer film having a thickness of about 135 μm. This polymer film was uniaxially stretched (longitudinal stretching).
Specifically, in a warming atmosphere of 15 ° C., after uniaxial stretching at a speed of 100 mm / min and confirming that necking has occurred, further in the same direction as the beginning at a speed of 6,000 mm / min. Uniaxial stretching was performed.

<Example 11>
In Example 10, the thickness of the polymer film was about 100 μm, the first stage longitudinal stretching speed was changed to 4,800 mm / min instead of 100 mm / min, and the second stage stretching was not performed. A resin film was produced in the same manner as in Example 1 except that.

<Example 12>
PHT (polyhexamethylene terephthalate 100% resin) with IV = 0.70 was extruded from a T-die using a melt extruder and solidified with a casting drum to obtain a polymer film having a thickness of about 100 μm. This polymer film was uniaxially stretched (longitudinal stretching).
Specifically, uniaxial stretching was performed at a speed of 5,200 mm / min in a heated atmosphere at 20 ° C.

<Example 13>
Isoactic PP (100% polypropylene resin, manufactured by Aldrich, Mw = 190,000, Mn = 50,000, MFI = 35 (ASTM D1238), IV = unknown) was extruded from a T-die using a melt extruder and solidified with a casting drum. A polymer film having a thickness of about 150 μm was obtained. This polymer film was uniaxially stretched (longitudinal stretching).
Specifically, uniaxial stretching was performed at a speed of 12,000 mm / min in a heated atmosphere at 35 ° C.

<Comparative Example 1>
In Example 1, a resin film was produced in the same manner as in Example 1 except that the stretching temperature was changed to 5 ° C. instead of 40 ° C.
Note that Comparative Example 1 broke as soon as the first stage of longitudinal stretching was started.

<Comparative example 2>
In Example 1, a resin film was produced in the same manner as in Example 1 except that the stretching temperature was changed to 100 ° C. instead of 40 ° C.
In Comparative Example 2, the occurrence of necking was not confirmed after the first-stage longitudinal stretching, and no cavities were developed even in the second-stage stretching.

<Comparative Example 3>
In Example 1, a resin film was produced in the same manner as in Example 1 except that the first stage longitudinal stretching speed was changed to 40,000 mm / min instead of 100 mm / min.
Note that Comparative Example 3 broke as soon as the first stage of longitudinal stretching was started.

<Comparative example 4>
As the resin film, Crispervoid PET (K2323) (manufactured by Toyobo Co., Ltd.) was used. The crisper void PET (K2323) contains inorganic particles as a cavity developing component with respect to the PET resin.

<Comparative Example 5>
Toyopearl SS (manufactured by Tosoh Corporation) was used as the resin film. The Toyopearl SS contains inorganic particles as a cavity developing component with respect to the polypropylene resin.

  Tables 2 and 3 collectively show the resin films of Examples 1 to 13 and Comparative Examples 1 to 5 prepared and obtained in this example.

-Evaluation method-
The following evaluation was performed about the resin film of the said Examples 1-13 and Comparative Examples 1-5.

(1) Measurement of thickness It measured using the Keyence company make, long range contact-type displacement meter AF030 (measurement part), AF350 (indication part).

(2) Measurement of thermal conductivity The thermal diffusivity was measured using TC-7000 (manufactured by Vacuum Riko Co., Ltd.). Both sides of the resin film were blackened by spraying and measured at room temperature. The density and specific heat were measured by the method described later, and the thermal conductivity was determined from the product of the three measured values.

(3) Measurement of density A certain area was cut out from the resin film, its mass was measured with a balance, its thickness was measured with a film thickness meter, and the density was determined by dividing the mass by volume.

(4) Measurement of specific heat The specific heat was determined by the method described in JIS K7123. As the DSC, Q1000 (manufactured by TA Instruments) was used.

(5) Measurement of surface smoothness Using an optical interference type three-dimensional shape analyzer NewView 5022 (manufactured by Zygo), measurement was performed with an objective lens 50 times.

(6) Measurement of void content Specific gravity was measured and calculated based on this specific gravity.
Specifically, the void content was calculated by the following equation (1).
Cavity content (%) = {1- (density of resin film after stretching) / (density of polymer film before stretching)} (1)

(7) Aspect ratio measurement A cross section perpendicular to the surface of the resin film and perpendicular to the longitudinal stretching direction (see FIG. 2B), and a cross section perpendicular to the surface of the resin film and parallel to the longitudinal stretching direction. (See FIG. 2C) was examined using a scanning electron microscope at an appropriate magnification of 300 to 3000 times, and a measurement frame was set in each cross-sectional photograph. This measurement frame was set so that 50 to 100 cavities were included in the measurement frame. Moreover, it confirmed that the cavity was orientating along the vertical extending | stretching direction by the examination by the said scanning electron microscope.
Next, the number of cavities included in the measurement frame is measured, and the number of cavities included in the measurement frame having a cross section perpendicular to the longitudinal stretching direction (see FIG. 2B) is m and the cross section parallel to the longitudinal stretching direction. The number of cavities included in the measurement frame (see FIG. 2C) was n.
Then, the longitudinal stretching direction perpendicular cross section of the measurement frame to measure the thickness (r _i) of each one of the cavities included in (Fig. 2B see), and the thickness of the average and r. Further, the length (L _i ) of each cavity included in the measurement frame (see FIG. 2C) having a cross section parallel to the longitudinal stretching direction was measured, and the average length was defined as L.
That is, r and L can be represented by the following formulas (3) and (4), respectively.
r = (Σr _i ) / m (3)
L = (ΣL _i ) / n (4)
Then, L / r was calculated as an aspect ratio.

(8) Evaluation of printing quality-Production of image-receiving sheet for thermal transfer recording-
First, the resin film surfaces of Examples 1 to 13 and Comparative Examples 1 to 5 were subjected to the treatment described below to prepare image receiving sheets for thermal transfer recording.

The surface of the paper support laminated on both sides with polyethylene was subjected to corona discharge treatment and then provided with a gelatin subbing layer containing sodium dodecylbenzenesulfonate. On the single-sided layer, the resin films of Examples 1 to 13 and Comparative Examples 1 to 5 were laminated by heat to provide a heat insulating layer. Next, it applied with the bar coater in order of the white intermediate | middle layer of the following composition, and the receiving layer. Each coating amount after drying of the white intermediate layer 1.0 g / ^{m 2,} was coated to a receptor layer 4.0 g / ^{m 2.} Drying was performed at 110 ° C. for 30 seconds for each layer.

--White intermediate layer--
Polyester resin (Byron 200, trade name, manufactured by Toyobo Co., Ltd.) 10 parts by weight fluorescent whitening agent (Uvitex OB, trade name, manufactured by Ciba Geigy) 1 part by weight Titanium oxide 30 parts by weight methyl ethyl ketone / toluene (1/1) 90 parts by mass

--Receptive layer--
100 parts by mass of vinyl chloride-vinyl acetate resin (Solvine A, trade name, manufactured by Nissin Chemical Industry Co., Ltd.)
Amino-modified silicone 5 parts by mass (manufactured by Shin-Etsu Chemical Co., Ltd., trade name, X22-3050C)
5 parts by mass of epoxy-modified silicone (manufactured by Shin-Etsu Chemical Co., Ltd., trade name, X22-300E)
Methyl ethyl ketone / toluene (= 1/1) 400 parts by mass Benzotriazole UV absorber 5 parts by mass (Tinuvin 900, trade name, manufactured by Ciba Specialty Chemicals)

-Printing method-
Next, Fujifilm VP8100 manufactured by Fuji Film Co., Ltd. was used as a color printer, a dedicated ribbon was set, test printing was performed on the receiving layer-forming surface of the image-receiving sheet for thermal transfer recording, and evaluation was performed by a sensory test using a tester. The image-receiving sheet for thermal transfer recording was lined with a high-quality paper (thickness: about 130 μm) with an adhesive and used for the test.
The test printing includes a printing test 1 for printing the output of the thermal transfer head of the color printer with a normal output, and a printing test 2 for printing the output of the thermal transfer head of the color printer with a normal output of 60%. It was.

-Evaluation criteria-
Evaluation criteria in the print test 1 and the print test 2 are as follows.
◎ ・ ・ ・ No unevenness or blurring in the image.
○: There is no unevenness or fading in the image, and the print density is sufficient. Although there is a tendency that the light-colored portion is slightly thinned, it is a level that cannot be understood unless compared, and there is no practical problem.
Δ: Slight unevenness is observed in the light-colored portion, but there is no practical problem.
X: Fading is observed in any one of yellow, magenta, and cyan colors, and the color of the image is not slightly transferred to the image receiving sheet side, and the color is partially discontinuously lightened (hereinafter referred to as the following) Called "colors fly"). “White spots” are observed in the solid black portion (the minute portion that should originally be colored is not colored but is white). There are practical problems.

(9) Measurement of the distance from the cavity closest to the film surface to the film surface Using a scanning electron microscope, a cross section perpendicular to the surface of the resin film and perpendicular to the longitudinal stretching direction (see FIG. 2D) The microscope was examined at an appropriate magnification of 300 to 3000 times, and a cross-sectional photograph was taken.
At the time of imaging, the resin film was set on a scanning electron microscope in a state where the resin film was placed on a plane, and the imaging was performed.
In the cross-sectional photograph, an arithmetic average value T of thickness was calculated. The arithmetic average value T of the thickness calculated in each resin film was the same as the thickness (see Tables 4 and 5) measured in the above “(1) Measurement of thickness”.
Next, an arbitrary straight line parallel to the thickness direction was drawn in the cross-sectional photograph, and another straight line parallel to the single straight line and separated by 20 × T was drawn. Moreover, it confirmed that the cavity was orientating along the vertical extending | stretching direction by the examination by the said scanning electron microscope.
Then, in each cavity in the cross-sectional photograph, the center of the circle that minimizes the sum of squares of deviations from the reference circle arbitrarily set by the maximum square center method was determined, and this was set as the center of the cavity.
Then, in the region sandwiched between the one straight line and the other straight line, ten cavities having the shortest distance from the center of the cavity to the upper surface of the resin film were selected. The “distance from the center of the cavity to the top surface of the resin film” refers to increasing the radius of the circle to be drawn in order when drawing a circle centered on the “center of the cavity”. The radius of the circle when touching the surface of.
And about 10 selected cavities, the distance h (i) from each center to the upper surface of the resin film is calculated, and the arithmetic average value h (avg) of each calculated distance h (i) is as follows ( 2) Calculated by the equation.
h (avg) = (Σh (i)) / 10 (2)

According to the result of the present example, the void-containing resin molded article of the present invention contains a void formed only of a crystalline polymer, and therefore, a void-expressing agent (thermal conductivity such as thermoplastic resin or inorganic particles) is formed in the void portion. It was confirmed that the thermal conductivity was small and greatly decreased (the X / Y ratio was small) compared to the thermal conductivity before stretching.
It has also been found that the surface smoothness is very good due to the unexpected result that cavities are formed only inside the cavity-containing resin molding. It was also shown that the printing properties are very good due to their physical properties.
In particular, from the results of the printing tests 1 and 2, the void-containing resin molded product of the present invention is not only when the output of the thermal transfer head is printed with a normal output, but also when printing with a normal output of 60%. However, it was confirmed that the image could be obtained at a level where there was no practical problem.

On the other hand, it was shown by Comparative Examples 1-3 that the void-containing resin molded product of the present invention cannot be produced if the stretching conditions are not suitable even if the resins are the same.
Further, from the results of the printing tests 1 and 2, in Comparative Examples 4 and 5 which are films in which cavities are formed by a cavity forming agent, there is no practical problem when the output of the thermal transfer head is printed at normal output. In this case, it was confirmed that when the image was printed with a normal output of 60%, the obtained image was at a level causing a practical problem. The reason for this is that in Comparative Examples 4 and 5, the cavity forming agent occupies a part of the cavity to be originally opened and becomes a heat path from the film surface to the back surface (exists in a bridge shape). When the cavity forming agent itself has a high thermal conductivity, the cavity forming agent promotes heat conduction from the front surface to the back surface of the film, or promotes heat conduction in the polymer layer. it seems to do.
Further, the surface of the void-containing resin molded product containing the void-forming agent tends to be relatively rough, so that it is difficult for the image receiving sheet to hit the transfer head uniformly, and the color is likely to fly. It is done.
In addition, when the cross-sectional photograph (SEM) was measured by cutting a cross-section of the thermal transfer recording image-receiving sheet of this example, in the thermal transfer recording image-receiving sheet produced using the resin film of Examples 1-13, The cavity of the heat insulation layer was preserved.

FIG. 1 is a diagram showing an example of a method for producing a void-forming resin molded body according to the present invention, and is a flow diagram of a biaxially stretched film production apparatus. FIG. 2A is a diagram for specifically explaining the aspect ratio, and is a perspective view of the void-containing resin molded body. FIG. 2B is a diagram for specifically explaining the aspect ratio, and is a cross-sectional view taken along the line A-A ′ of the void-containing resin molded body in FIG. 2A. FIG. 2C is a diagram for specifically explaining the aspect ratio, and is a B-B ′ sectional view of the void-containing resin molded body in FIG. 2A. FIG. 2D is a cross-sectional view taken along the line A-A ′ in FIG. 2A for explaining a method of measuring the distance from the film surface of the ten cavities located closest to the film surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cavity containing resin molding 1a Surface 100 Cavity L Length of cavity in aspect ratio r Thickness of cavity in aspect ratio

Claims (5)

A void-containing resin molded article comprising a polymer composition consisting only of a polymer having crystallinity, and containing a long cavity in a state in which the length direction is oriented in one direction,
The polymer having crystallinity includes at least one selected from polybutylene terephthalate, polyhexamethylene terephthalate, polybutylene succinate, and polypropylene,
A polymer molded body made of a polymer composition and containing no voids at a speed of 10 to 36,000 mm / min, a stretching temperature of T (° C.), and a glass transition temperature of a crystalline polymer of Tg (° C.) And (Tg-30) (° C) ≤ T (° C) ≤ (Tg + 50) including a cavity formed by stretching at a stretching temperature T (° C) in the range shown by
The ten cavities having the shortest distance from the center of the cavity to the surface of the cavity-containing resin molding in the cross section perpendicular to the orientation direction of the cavity in the cavity-containing resin molding, from each center to the cavity. The distance h (i) to the surface of the containing resin molding is calculated, and the calculated arithmetic mean value h (avg) of each of the distances h (i) is expressed by the following formula: h (avg)> T / 100 Meet relationships,
[However, T represents an arithmetic average value of thicknesses in the cross section, and the ten cavities are parallel to the straight line in parallel with the thickness direction, and parallel to the straight line and only 20 × T. It is selected from cavities existing in a region sandwiched by other straight lines located apart from each other. ]
And the thermal conductivity of the said cavity containing resin molding is set to X (W / mK), and it is the same thickness as the said cavity containing resin molding, and the same polymer composition as the polymer composition which comprises the said cavity containing resin molding A void-containing resin molded article characterized by having an X / Y ratio of 0.27 or less when the thermal conductivity of a polymer molded article containing no voids is Y (W / mK) A polymer molded body obtained by melt-molding a polymer composition comprising crystalline polyester at a draft ratio of 500 or less in air under a temperature atmosphere of Tg (° C.) or less and a stretching speed of 3 m / min or more and a draw ratio of 1.1 times Excluding void-containing resin moldings formed by heat treatment after stretching 10 times. A void-containing resin molded article comprising a polymer composition consisting only of a polymer having crystallinity, and containing a long cavity in a state in which the length direction is oriented in one direction,
The polymer having crystallinity includes at least one selected from polybutylene terephthalate, polyhexamethylene terephthalate, polybutylene succinate, and polypropylene,
A polymer molded body made of a polymer composition and containing no voids at a speed of 10 to 36,000 mm / min, a stretching temperature of T (° C.), and a glass transition temperature of a crystalline polymer of Tg (° C.) And (Tg-30) (° C) ≤ T (° C) ≤ (Tg + 50) including a cavity formed by stretching at a stretching temperature T (° C) in the range shown by
The ten cavities having the shortest distance from the center of the cavity to the surface of the cavity-containing resin molding in the cross section perpendicular to the orientation direction of the cavity in the cavity-containing resin molding, from each center to the cavity. The distance h (i) to the surface of the containing resin molding is calculated, and the calculated arithmetic mean value h (avg) of each of the distances h (i) is expressed by the following formula: h (avg)> T / 100 Meet relationships,
[However, T represents an arithmetic average value of thicknesses in the cross section, and the ten cavities are parallel to the straight line in parallel with the thickness direction, and parallel to the straight line and only 20 × T. It is selected from cavities existing in a region sandwiched by other straight lines located apart from each other. ]
And a void-containing resin molded article having a thermal conductivity of 0.1 (W / mK) or less (however, a polymer molding obtained by melt-molding a polymer composition comprising crystalline polyester at a draft ratio of 500 or less) The void-containing resin molded body formed by stretching the body in air under a temperature atmosphere of Tg (° C.) or less and stretching at a stretching speed of 3 m / min or more and a stretching ratio of 1.1 to 10 times, followed by heat treatment. except for). The void content is 3% by volume or more and 50% by volume or less,
L / r ratio when the average length of the cavity in the thickness direction orthogonal to the orientation direction of the cavity is r (μm) and the average length of the cavity in the orientation direction of the cavity is L (μm), The void-containing resin molded product according to any one of claims 1 to 2, which is 10 or more. A method for producing a void-containing resin molded product according to any one of claims 1 to 3,
The void-containing resin molded body is made of a polymer composition, and the polymer molded body not containing the void is formed at a speed of 10 to 36,000 mm / min, and
When the stretching temperature is T (° C) and the glass transition temperature of the polymer having crystallinity is Tg (° C),
(Tg-30) (° C.) ≦ T (° C.) ≦ (Tg + 50) (° C.)
A method for producing a void-containing resin molded body comprising a step of stretching at a stretching temperature T (° C.) in a range represented by (however, a polymer molded body obtained by melt molding a polymer composition comprising a crystalline polyester at a draft ratio of 500 or less, Except for the method for producing a void-containing resin molded article, which includes a step of heat-treating after stretching at a stretching speed of 3 m / min or more and a stretching ratio of 1.1 to 10 times in air under a temperature atmosphere of Tg (° C.) or less. ). An image receiving film or sheet for a sublimation transfer recording material or a thermal transfer recording material containing the void-containing resin molded product according to claim 1.