JP2010110901A - Method for manufacturing resin molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for surely manufacturing a molding having superior oxygen permeation prevention performance and other superior functions by inclining or stepping resin components in the resin molding after being molded. <P>SOLUTION: When a mixture in which a low oxygen-permeable resin having an oxygen permeation coefficient of 1.0×10<SP>-21</SP>mol×m/(m<SP>2</SP>×s×Pa) or below and a resin having another function are blended is melt-molded, the surface temperatures T<SB>1</SB>and T<SB>2</SB>of both surfaces 1 and 2 in the thickness direction of the molten molding 10 are made higher than the crystallization temperature T<SB>c</SB>of the low oxygen-permeable resin, and heat treatment is carried out to satisfy prescribed conditions concerning the temperature gradient in the thickness direction of the molten molding 10 and the time for maintaining the temperature gradient. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a resin molded body, and more specifically, in a production method for forming a molded body having different compositions in the thickness direction using a resin composition containing two or more thermoplastic resins. The present invention relates to a method for producing a resin molded body whose quality is stabilized.

  Conventionally, in order to obtain a resin molded body having various functions such as gas barrier properties, durability, and adhesiveness, resin sheets each having unique functions are individually molded, and the plurality of resin sheets are laminated. Multilayer laminates have been used. However, in order to manufacture such a multilayer laminate, a plurality of extruders are required, and it is necessary to provide an adhesive layer for bonding the resin sheets extruded from the respective extruders. The problem is that the cost increases as the number of materials increases.

  As described above, Patent Document 1 discloses two or more types of methods for producing a resin molded body having various functions without requiring a large amount of production equipment and a lamination process necessary for producing a multilayer laminate. By melt-molding a mixture of resins and performing a heat treatment so as to give a temperature difference to the melt-formed body in the thickness direction, a plurality of resin components in the resin-formed body are inclined in the thickness direction or A method of manufacturing a resin molded body that can be stepped is proposed.

However, the present inventor has the manufacturing method of Patent Document 1 which is superior in productivity and cost as compared with the conventional multilayer laminate, and has a low oxygen permeable resin whose oxygen permeability coefficient is below a certain level and other functions. It was applied to a mixture with a resin, and while trying to obtain a resin molded body having high oxygen permeation prevention properties and other excellent functions, the resin component in the resin molded body was not necessarily inclined or stepped. It was found that the expected performance was not obtained. That is, in applying the production method of Patent Document 1 to a mixture of a low oxygen permeability resin having an oxygen permeability coefficient of a certain level or less and a resin having other functions, a plurality of techniques must be used without further technical improvement. The resin component in the resin molded body made of a mixture of thermoplastic resins maintains the same uniform blended state as before molding, and has the desired excellent oxygen permeation preventive properties and other excellent functions. No body can be obtained.
JP 2004-268568 A

  An object of the present invention is to provide a resin in a molded resin body after molding when a resin molded body is produced from a mixture of a resin having an oxygen permeability coefficient of a certain level or less and a resin having other functions by the production method of Patent Document 1. An object of the present invention is to provide a method for producing a resin molded body capable of reliably producing a molded body having both excellent oxygen permeation preventing performance and other excellent functions by inclining or stepping components.

The method for producing a resin molded body according to the first aspect of the present invention, which achieves the above object, comprises melt-molding a mixture obtained by blending at least two types of thermoplastic resins having different functions, and then forming a molten molded body in the thickness direction. In the method for producing a resin molded body in which a heat treatment that gives a temperature gradient is performed and the resin component in the melt molded body is inclined or stepped in the thickness direction, the mixture of the thermoplastic resins has an oxygen permeability coefficient of 1.0. ^{X10 -21} mol · m / (m ² · s · Pa) or less of a mixture of a low oxygen permeable resin and a resin having other functions, and both sides in the thickness direction of the melt-formed product by the heat treatment The surface temperatures T ₁ (° C.) and T ₂ (° C.) given to the above are made higher than the crystallization temperature T _c of the low oxygen permeable resin, and different temperatures T ₁ > T ₂ from each other. T ₁ -T ₂ ) The temperature gradient α ₁ (° C./mm)=(T ₁ −T ₂ ) / d with respect to the thickness d (mm) is set to 100 ° C./mm or more, and t ₁ = (1 / α ₁ ) × 1000. It is characterized in that it lasts for at least t ₁ (min). The temperature gradient α ₁ is preferably in the range of 100 to 1000 ° C./mm.

The method for producing a resin molded body according to the second aspect of the present invention that achieves the above-mentioned object is the method of melt-molding a mixture obtained by blending at least two types of thermoplastic resins having different functions, and then forming the molten molded body in the thickness direction. In the method for producing a resin molded body in which a heat treatment that gives a temperature gradient is performed and the resin component in the melt molded body is inclined or stepped in the thickness direction, the mixture of the thermoplastic resins has an oxygen permeability coefficient of 1.0. ^{X10 -21} mol · m / (m ² · s · Pa) or less of a mixture of a low oxygen permeable resin and a resin having other functions, and both sides in the thickness direction of the melt-formed product by the heat treatment The surface temperatures T ₁ (° C.) and T ₂ (° C.) applied to the same are set higher than the crystallization temperature T _c of the low oxygen permeable resin and set to the same temperature T ₁ = T _2. Surface temperature T ₁ (T ₂ ) and the melting Temperature gradient with respect to the thickness of the melt molded product d of (mm) of one half (d / 2) | temperature difference between the temperature T _m of a thickness direction center of the molded body _{| T 1 (T 2) -T} m α ₂ (° C./mm)=|T ₁ (T ₂ ) −T _m | / (d / 2) is set to 100 ° C./mm or more, and t ₂ defined by t ₂ = (1 / α ₂ ) × 1000 It is characterized by lasting more than ₂ minutes. The temperature gradient α ₂ is preferably in the range of 100 to 1000 ° C./mm.

  This manufacturing method is suitable when the resin molded body is a film. The low oxygen permeable resin may be at least one selected from polyamide resin, polyvinyl alcohol resin, ethylene vinyl alcohol copolymer resin, and polyvinylidene chloride resin. The resin having a function other than the low oxygen permeable resin may be at least one selected from polyethylene resin, polypropylene resin, and polystyrene resin.

According to the method for producing a resin molded body of the first aspect of the present invention, a low oxygen permeable thermoplastic resin having an oxygen permeability coefficient of 1.0 × 10 ⁻²¹ mol · m / (m ² · s · Pa) or less and Surface temperatures T ₁ (° C.) and T ₂ (T) (which are applied to both sides in the thickness direction of a molded article in a molten state when a mixture obtained by blending two or more kinds of thermoplastic resins including resins having other functions is melt-molded. ° C) higher than the crystallization temperature T _c of the low oxygen-permeable resin, and different temperatures T ₁ > T ₂ , and the thickness d of the melt molded product having the temperature difference (T ₁ -T ₂ ) The temperature gradient α ₁ (° C./mm) with respect to (mm) is set to 100 ° C./mm or more and is maintained for a time of t ₁ (min) or more defined by t ₁ = (1 / α ₁ ) × 1000. Therefore, the resin component in the molded resin body after molding is inclined or stepped in the thickness direction to reduce the oxygen content. Excellent oxygen permeation prevention performance and other excellent functions to make the layer with a high ratio of permeable resin and a layer with a high ratio of resin having other functions substantially separated in the thickness direction Thus, it is possible to reliably produce a molded body having both.

According to the second method for producing a resin molded body of the present invention, a low oxygen-permeable thermoplastic resin having an oxygen permeability coefficient of 1.0 × 10 ⁻²¹ mol · m / (m ² · s · Pa) or less and Surface temperatures T ₁ (° C.) and T ₂ (T) (which are applied to both sides in the thickness direction of a molded article in a molten state when a mixture obtained by blending two or more kinds of thermoplastic resins including resins having other functions is melt-molded. _{Is set} to be higher than the crystallization temperature T _c of the low oxygen permeable resin and set to the same temperature T ₁ = T ₂ , and the same surface temperature T ₁ (T ₂ ) temperature difference between the temperature T _m of a thickness direction central _{| T 1 (T 2) -T} m | thickness d of the melt molded product (mm) of one half (d / 2) temperature gradient for alpha ₂ (° C. / mm) was brought to 100 ° C. / mm or more and, t ₂ = (duration 1 / α ₂₎ t ₂ (min defined by × 1000) or longer Since the resin component in the molded resin body after molding is inclined or stepped in the thickness direction, the presence of a resin with a high proportion of low oxygen-permeable resin and other functions A layer having a high ratio is formed in a three-layer structure in which one layer is substantially collected in the center in the thickness direction and the other layer is sandwiched from both sides. A molded body having an excellent function can be reliably produced.

The present invention is to produce a resin molded product having a low oxygen permeability function and other functions such as durability, and blended at least two thermoplastic resins having different functions as raw materials. A mixture is used, and at least one of them has an oxygen permeability coefficient of 1.0 × 10 ⁻²¹ mol · m / (m ² · s · Pa) or less, preferably 1.0 × 10 ⁻²³ mol · m. / (M ² · s · Pa) or less resin. When the oxygen permeation coefficient exceeds 1.0 × 10 ⁻²¹ mol · m / (m ² · s · Pa), the oxygen permeation prevention performance of the resin molding cannot be sufficiently improved. In the present invention, the oxygen transmission coefficient is a value measured under conditions of a temperature of 23 ° C. and a humidity of 0% RH in accordance with JIS K7126.

  The low oxygen permeability resin is not particularly limited as long as it has the above-described oxygen permeability coefficient. For example, polyamide resin, polyvinyl alcohol resin, ethylene vinyl alcohol copolymer resin, polyvinylidene chloride resin, polyester resin Etc. can be illustrated. Among them, the low oxygen permeable resin is preferably at least one selected from polyamide resin, polyvinyl alcohol resin, ethylene vinyl alcohol copolymer resin, and polyvinylidene chloride resin. These low oxygen permeable resins may be used alone or in combination of two or more.

  A thermoplastic resin having a function other than low oxygen permeability is a resin that imparts at least one function selected from durability, adhesion, moisture resistance, and fatigue resistance. Such a thermoplastic resin is not particularly limited, and examples thereof include a polyethylene resin, a polypropylene resin, a polystyrene resin, a modified polyethylene resin, and a modified propylene resin. Of these, polyethylene resin and polypropylene resin can improve the durability and moisture resistance of the molded resin. The modified polypropylene resin has a function of improving the adhesiveness of the resin molded body. Only one kind of these thermoplastic resins may be used, or two or more kinds may be used in combination.

  The blending ratio of the low oxygen permeable resin in the mixture of two or more thermoplastic resins is preferably 10 to 90% by weight, more preferably 20 to 80% by weight. When the amount of the low oxygen permeable resin is less than 10% by weight, the oxygen permeation preventive property of the resin molding cannot be sufficiently obtained. On the other hand, when the amount of the low oxygen permeable resin exceeds 90% by weight, the thermoplastic resin having another function cannot sufficiently exhibit its function. The method of melt-kneading at least two kinds of thermoplastic resins including a low oxygen-permeable resin and a thermoplastic resin having other functions is not particularly limited. For example, a single-screw extruder, a twin-screw kneader A continuous kneader, a kneader, a Banbury mixer or the like can be used.

  In the production method of the present invention, a mixture of a thermoplastic resin composed of a low-oxygen permeable thermoplastic resin and a thermoplastic resin having other functions is melt-molded, and a heat treatment is applied to give a temperature gradient to the melt-molded body. A resin molded body composed of two or three layers having different compositions in the molded body is produced. Therefore, unlike the multilayer laminated body manufactured by multilayer extrusion molding or laminate molding, this resin molded body does not need to be provided with an adhesive layer, so that the material cost can be reduced. Moreover, since it is not necessary to use a plurality of extruders, the equipment cost can be reduced. Furthermore, when forming a molded body in a molten state, a resin molded body composed of two or three layers can be stably produced by performing a heat treatment that satisfies any of the conditions described later.

  In the method for producing a resin molded body of the present invention, a mixture of a low oxygen-permeable resin and a resin having other functions is melt-molded, and then in the thickness direction according to the conditions described in detail below for the molten molded body. A heat treatment that gives a temperature gradient is performed. That is, in a normal melt molding, after a mixture of thermoplastic resins is melted, the melt is shaped and subjected to a predetermined heat treatment before cooling to obtain a resin molded body having a different composition in the thickness direction. Form. Therefore, in the present invention, each operation in normal melt molding can be applied as it is to the step of melting the thermoplastic resin mixture, the step of shaping, and the step of cooling.

  FIG. 1 is an explanatory view schematically showing an example of a step of performing a heat treatment on a molded body in a molten state in the method for producing a resin molded body of the present invention.

In FIG. 1, a molded product 10 in a molten state of a resin composition is extruded from a T die 21 of an extruder 20 into a film shape or a sheet shape in the direction of an arrow M. A heat source 22 is arranged on the one-side surface 1 in the thickness direction of the molded body 10 in a molten state so that the surface temperature of the surface 1 becomes T ₁ (° C.). A heat source 23 is disposed on the surface 2 opposite to the thickness direction of the molded body 10 so that the surface temperature of the surface 2 is T ₂ (° C.). These surface temperatures T ₁ (° C.) and T ₂ (° C.) may be temperatures obtained by measuring the surface temperature of the molded body in the molten state, or may be the temperatures of the heat sources 22 and 23. . The heat sources 22 and 23 are not particularly limited as long as the surface temperatures T ₁ (° C.) and T ₂ (° C.) can be adjusted. For example, an electric heater, an oil bath, and a mold whose temperature can be adjusted. Etc. can be illustrated.

In the present invention, the surface temperatures T ₁ (° C.) and T ₂ (° C.) of the molten compact in the heat treatment step must be higher than the crystallization temperature T _c (° C.) of the low oxygen permeable resin. Don't be. By making the surface temperatures T ₁ (° C.) and T ₂ (° C.) higher than the crystallization temperature T _c (° C.), diffusion of the low oxygen-permeable resin is facilitated, and the proportion of the low oxygen-permeable resin is present. Can be easily formed. The surface temperatures T ₁ (° C.) and T ₂ (° C.) are preferably 10 ° C. or more, more preferably 20 ° C. to 100 ° C. higher than the crystallization temperature T _c (° C.).

In the present invention, the crystallization temperature T _{c of} the low oxygen permeable resin is determined from a temperature 30 ° C. higher than the melting point of the low oxygen permeable resin using a differential scanning calorimeter (DSC) in accordance with JIS K7121. What is calculated | required from the exothermic peak obtained when it cools and measures at 10 degrees C / min to 40 degreeC.

According to a first aspect of the present invention, there is provided a method for producing a resin molded body, wherein a resin component in a molded resin body after molding is inclined or stepped in the thickness direction, A resin molded body having a form in which a layer having a high ratio of a resin having another function is adjacent is manufactured. The heat treatment conditions in the production method of the first aspect of the present invention are such that the surface temperatures T ₁ (° C.) and T ₂ (° C.) of the molded body in the molten state are set to different temperatures T ₁ > T ₂ and the temperature difference (T ₁ -T ₂ temperature gradient alpha ₁ to the thickness d of the melt molded product (mm) of) (℃ / mm) = ( T 1 -T 2) / d was above 100 ° C. / mm, and t ₁ = ₍₁ / It lasts for a time equal to or greater than t ₁ (min) defined by α ₁ ) × 1000.

The temperature gradient α ₁ is 100 ° C./mm or more, preferably 100 to 1000 ° C./mm. When the temperature gradient α ₁ is less than 100 ° C./mm, the resin component in the molded resin molded body cannot be inclined or stepped in the thickness direction, and the proportion of the low oxygen-permeable resin is present. Since it is not possible to stably form a resin molded body having two layers, a high layer and a layer having a high ratio of resin having other functions, it has excellent oxygen permeation prevention performance and other excellent functions. It is impossible to reliably produce a combined molded body.

Further, when the temperature gradient α ₁ is large, the time for maintaining α ₁ can be shortened, and when the temperature gradient α ₁ is small, it is necessary to lengthen the time for maintaining α ₁ . Time t ₁ (min) is the lower limit of the time for maintaining the temperature gradient alpha ₁ which is determined in correspondence with the temperature gradient alpha _1, a relational expression _{t 1 = (1 / α 1} ) × 1000 The diffusion of polymer The coefficient D is 1 × 10 ⁻⁹ cm ² / s, which is derived in consideration of the fact that this increases with temperature. When the time for maintaining the temperature gradient α ₁ is less than t ₁ (minutes), the resin component in the molded resin article after molding cannot be inclined or stepped in the thickness direction, and has low oxygen permeability. It is not possible to stably form a resin molded body having two layers, ie, a layer having a high abundance ratio of the resin and a layer having a high abundance ratio of resins having other functions. The time for maintaining the temperature gradient α ₁ is preferably 1 to 10 times the time t ₁ (min).

Incidentally, the crystallization temperature T _c of the low oxygen permeability of the thermoplastic resin, is higher than the crystallization temperature of the thermoplastic resin having other functions, low oxygen permeability in the surface 1 side with high surface temperatures T ₁ The presence ratio of the functional resin is higher than the blending ratio when the mixture is blended. Further, when the crystallization temperature T _c of the low oxygen permeable resin is lower than the crystallization temperature of the thermoplastic resin having other functions, it has other functions on the surface 1 side having the high surface temperature T _1. The abundance ratio of the thermoplastic resin is higher than the blending ratio when the mixture is blended.

In the method for producing a resin molded body of the second aspect of the present invention, the resin component in the resin molded body after molding is inclined or stepped in the thickness direction, and a layer having a high proportion of low oxygen-permeable resin and A resin molded body having a three-layer structure in which one layer selected from layers having a high ratio of resin having other functions is sandwiched between the other layers is produced. The heat treatment conditions in the manufacturing method of the second aspect of the present invention are that the surface temperatures T ₁ (° C.) and T ₂ (° C.) are set to the same temperature T ₁ = T ₂ , and the same surface temperatures T ₁ and T _{2 are set.} a temperature difference between the temperature T _m of a thickness direction center of the melt molded product _{| T 1 -T m |, |} T 2 -T m | of one-half of the thickness d (mm) of the melt-molded bodies (d / The temperature gradient α ₂ (° C./mm) with respect to 2) is set to 100 ° C./mm or more and is maintained for a time of t ₂ (min) or more defined by t ₂ = (1 / α ₂ ) × 1000. | T ₁ −T _m | and | T ₂ −T _m | mean the absolute values of the differences between the temperatures T ₁ and T ₂ and T _m , respectively. Further, T _m is the temperature [° C.] at the center in the thickness direction of the molded body in the molten state, and in the example of FIG. 1, is the resin temperature of the melt when extruded from the T die.

The temperature gradient α ₂ is 100 ° C./mm or more, preferably 100 to 1000 ° C./mm. When the temperature gradient α ₂ is less than 100 ° C./mm, the resin component in the resin molded body after molding cannot be inclined or stepped in the thickness direction, and the presence ratio of the low oxygen-permeable resin is low. Since it is impossible to stably form a resin molded body having three layers sandwiched between one layer selected from a high layer and a layer having a high ratio of resin having other functions, the other layer is excellent. Therefore, it is impossible to reliably produce a molded product having both oxygen permeation preventing performance and other excellent functions.

Further, when the temperature gradient α ₂ is large, the time for maintaining α ₂ can be shortened, and when the temperature gradient α ₂ is small, it is necessary to lengthen the time for maintaining α ₂ . Time t ₂ (min) is the lower limit of the time for maintaining the temperature gradient alpha ₂ which is determined in correspondence with the temperature gradient alpha _2, a relational expression _{t 2 = (1 / α 2} ) × 1000 The diffusion of polymer The coefficient D is 1 × 10 ⁻⁹ cm ² / s, which is derived on the basis that this increases with temperature. When the time for maintaining the temperature gradient α ₂ is less than t ₂ (minutes), the resin component in the molded resin article after molding cannot be inclined or stepped in the thickness direction, and low oxygen permeability A resin molded body having three layers in which one layer selected from a layer having a high resin content ratio and a layer having a high resin content ratio having another function is sandwiched between the other layers is stably formed. I can't. The time for maintaining the temperature gradient α ₂ is preferably 1 to 10 times the time t ₂ (min).

When the crystallization temperature T _c of the low oxygen permeable thermoplastic resin is higher than the crystallization temperature of the thermoplastic resin having other functions, both surfaces of the melt-formed product are heat-treated at a low temperature, that is, T _{When m} > T ₁ = T ₂ > T _c , there are three layers in which a layer having a high ratio of low oxygen-permeable resin is sandwiched between two layers having a high ratio of thermoplastic resin having other functions. A resin molded body composed of layers is formed. Further, when both surfaces of the melt-formed body are heat-treated at a high temperature, that is, when T ₁ = T ₂ > T _m > T _c , other functions are provided between two layers having a high ratio of low oxygen-permeable resin. A resin molded body composed of three layers in which a layer having a high thermoplastic resin content is sandwiched is formed. On the other hand, when the crystallization temperature _Tc of the low oxygen permeable resin is lower than the crystallization temperature of the thermoplastic resin having other functions, the resin molded body composed of three layers in which the above-described layer structure is reversed. Is formed.

  The manufacturing method described above is a method in which a predetermined heat treatment is performed on the molten molded body extruded from the T die 21. However, the heat treatment described above may be performed in advance inside the T die 21.

  FIG. 1 shows an example of a manufacturing method using a T die. When a cylindrical film is formed using a circular die, the above-described temperature gradient is set between the outer die and the inner die. By providing, resin molded bodies having different compositions in the thickness direction can be stably produced.

  The melt molding method to which the present invention is applied is not particularly limited, and for example, extrusion molding, inflation molding, blow molding, injection molding, calendar molding, and the like are preferable, and extrusion molding and calendar molding are particularly preferable. In inflation molding and blow molding, the heat treatment described above may be performed before the step of blowing air into the melt-molded product. In injection molding, a temperature gradient can be applied between the cavity side mold and the core side mold. In calendering, a temperature gradient can be applied between opposing rolls.

  In the resin molded product obtained by the production method of the present invention, the layer having a high proportion of low oxygen-permeable resin means that the average composition, that is, the proportion of the low oxygen-permeable resin in the mixture at the time of blending is low oxygen A layer having a large ratio of the permeable resin. The layer having a high ratio of low oxygen-permeable resin is preferably a layer in the thickness direction in which the low oxygen-permeable resin is a main component and forms a continuous phase. More preferably, the low oxygen-permeable resin layer has a high density in the layer in which the low-oxygen-permeable resin forms a dendritic continuous phase. On the other hand, in the layer having a high ratio of the thermoplastic resin having other functions, the thermoplastic resin having other functions than the average composition, that is, the blending ratio of the thermoplastic resins having other functions in the mixture at the time of blending. The presence ratio of is increasing.

  In addition, the boundary between the low oxygen-permeable resin layer and the low layer may be changed step by step, or the low oxygen-permeable resin content may change stepwise. It may be inclined such that the existence ratio gradually changes.

  Since the resin molded product obtained by the production method of the present invention is particularly excellent in oxygen permeation prevention performance, it is suitable for use in food packaging containers, beverage containers, other gas-filled and oxidation-resistant containers, and the like.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, the scope of the present invention is not limited to these Examples.

Preparation of mixture blended with thermoplastic resin Ethylene vinyl alcohol copolymer resin (EVOH, Kuraray Eval H171B, oxygen transmission coefficient 1.6 × 10 ⁻²⁴ mol · m / (m ² · s · Pa), crystallization The temperature _Tc is 148 ° C.) and 50% by weight. The polyethylene resin (LDPE, Novatec YF30 manufactured by Nippon Polyethylene Co., Ltd. has a function of improving the durability of the resin molded body and the crystallization temperature is 91 ° C.). A mixture of thermoplastic resins was prepared by kneading and granulating using a biaxial kneader.

Production of resin molded body (Examples 1 to 4, Comparative Examples 1 to 4 and 6 to 8)
The obtained thermoplastic resin mixture was supplied to a single-screw extruder having a T die, and a film having a thickness of 0.1 mm was extruded and formed under common conditions. As shown to 1 and 2, it heat-processed on 11 types of different conditions, and manufactured the film (Examples 1-4, Comparative Examples 1-4 and 6-8). The die temperature of the extruder was 220 ° C., and the resin temperature of the thermoplastic resin mixture extruded from the die (center temperature T _m in the thickness direction of the molded article in the molten state) was 230 ° C. In the heat treatment (except for Comparative Example 1) on the molded body in the molten state, electric heaters are arranged above and below the film, and the temperature of the upper electric heater (T ₁ ) and the temperature of the lower electric heater (T ₂ ). Were set as shown in Tables 1 and 2, respectively, and the heat treatment time was adjusted by changing the extrusion speed of the extruder.

Production of co-extruded multilayer film (Comparative Examples 5 and 9)
The multilayer film of Comparative Example 5 is made of ethylene vinyl alcohol copolymer resin (EVOH, Kuraray Eval H171B, oxygen permeability coefficient is 1.6 × 10 ⁻²⁴ mol · m / (m ² · s · Pa)). A 0.05 mm layer, a 0.02 mm thick layer made of maleated polyethylene resin (MA-PE, Mitsui Chemicals Admer) and a thickness of 0.02 mm made of polyethylene resin (LDPE, Novatec YF30 made by Nippon Polyethylene). A multilayer film in which three layers of 03 mm layers were laminated in this order was produced by coextrusion molding using three extruders. The thickness of the obtained multilayer film was 0.1 mm.

The multilayer film of Comparative Example 9 is made of ethylene vinyl alcohol copolymer resin (EVOH, Kuraray Eval H171B, oxygen permeability coefficient is 1.6 × 10 ⁻²⁴ mol · m / (m ² · s · Pa)). A layer with a thickness of 0.01 mm made of maleated polyethylene resin (MA-PE, Admer made by Mitsui Chemicals, Inc.) is laminated on both sides of this layer with a thickness of 0.05 mm as the center, and polyethylene on both sides of the outer layer. A multilayer film consisting of 5 layers in which layers having a thickness of 0.02 mm made of resin (LDPE, Novatec YF30 manufactured by Nippon Polyethylene Co., Ltd.) were laminated was produced by coextrusion molding using 5 extruders. The thickness of the obtained multilayer film was 0.1 mm.

Evaluation of Resin Molded Body A cross section of the obtained film was observed at a magnification of 100 times with an optical microscope, and EVOH was dissolved in dimethyl sulfoxide (DMSO), which is a good solvent, to evaluate a composition change (layer form) in the thickness direction. Moreover, the area ratio (%) of EVOH in the vicinity region of the upper surface in the thickness direction in the film cross section, the central region, and the vicinity region of the lower surface was determined, and are shown in Tables 1 and 2, respectively. The composition of the upper and lower surfaces was measured and calculated by infrared absorption spectrum and elemental analysis. Moreover, the oxygen permeation prevention performance and durability of the obtained film were evaluated by the following measuring methods.

Oxygen permeation prevention performance The oxygen permeation prevention performance of the obtained film was measured according to K7126 “Test method for gas permeability of plastic films and sheets (Method A)” under the conditions of a temperature of 23 ° C. and a humidity of 0% RH. The results obtained are shown in Tables 1 and 2. When the oxygen permeability coefficient is 1.0 × 10 ⁻²² mol · m / (m ² · s · Pa)) or less, it can be determined that there is practicality.

Durability Durability performance of the obtained film was repeated 500,000 times in an atmosphere of 50 ° C. by continuous tensile strain of 60 mm between chucks and a stroke of 10 mm using a dematcher crack tester manufactured by Ueshima Works. The case where breakage or peeling occurred due to the right of appeal was judged as “X”, and the case where neither breakage nor peeling occurred was judged as “◯”, and the obtained results are shown in Tables 1 and 2.

It is explanatory drawing which shows an example of the process of heat-processing the molded object in a molten state in the manufacturing method of the resin molded object of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Surface of melt-molded body 3 Thickness direction center of melt-molded body 10 Melt-formed body 20 Extruder 21 T die 22, 23 Heat source

Claims (7)

After melt-molding a blend of at least two thermoplastic resins having different functions from each other, a heat treatment is applied to the molten molded body to give a temperature gradient in the thickness direction, and the resin component in the molten molded body is thickened. In the method of manufacturing a resin molded body that is inclined or stepped in the direction,
As a mixture of the thermoplastic resin, a mixture of a low oxygen permeability resin having an oxygen permeability coefficient of 1.0 × 10 ⁻²¹ mol · m / (m ² · s · Pa) or less and a resin having other functions. The surface temperatures T ₁ (° C.) and T ₂ (° C.) applied to both surfaces in the thickness direction of the melt-formed product by the heat treatment are set higher than the crystallization temperature T _c of the low oxygen permeable resin. , to different temperatures T _1> T ₂ with each other, the temperature difference (T ₁ -T ₂₎ temperature gradient alpha ₁ to the thickness d (mm) of the melt molding of (℃ / mm) = (T 1 -T 2 ) / D is set to 100 ° C./mm or more, and the method for producing a resin molded product is maintained for a time of t ₁ (min) or more defined by t ₁ = (1 / α ₁ ) × 1000. Method for producing a resin molded article according to claim 1 for the temperature gradient alpha ₁ in the range of 100 to 1000 ° C. / mm. After melt-molding a blend of at least two thermoplastic resins having different functions from each other, a heat treatment is applied to the molten molded body to give a temperature gradient in the thickness direction, and the resin component in the molten molded body is thickened. In the method of manufacturing a resin molded body that is inclined or stepped in the direction,
As a mixture of the thermoplastic resin, a mixture of a low oxygen permeability resin having an oxygen permeability coefficient of 1.0 × 10 ⁻²¹ mol · m / (m ² · s · Pa) or less and a resin having other functions. The surface temperatures T ₁ (° C.) and T ₂ (° C.) applied to both surfaces in the thickness direction of the melt-formed product by the heat treatment are set higher than the crystallization temperature T _c of the low oxygen permeable resin. Are set to the same temperature T ₁ = T ₂ , and the temperature difference between the same surface temperature T ₁ (T ₂ ) and the temperature T _{m at the} center in the thickness direction of the melt-formed product | T ₁ (T ₂ ) − Temperature gradient α ₂ (° C./mm) with respect to one half (d / 2) of the thickness d (mm) of the melt-formed product of T _m | = T ₁ (T ₂ ) −T _m | / (d / 2) it is at least 100 ° C. / mm, and _{t 2 = (1 / α 2} ) t 2 ( min defined by × 1000) or resin molding to duration The method of production. The manufacturing method of the resin molding of Claim 3 which makes the said temperature gradient (alpha) ₂ the range of 100-1000 degrees C / mm.   The method for producing a resin molded body according to claim 1, wherein the resin molded body is a film.   The resin molded article according to any one of claims 1 to 5, wherein the low oxygen-permeable resin is at least one selected from polyamide resin, polyvinyl alcohol resin, ethylene vinyl alcohol copolymer resin, and polyvinylidene chloride resin. Production method.   The method for producing a resin molded body according to any one of claims 1 to 6, wherein the resin having a function other than the low oxygen permeable resin is at least one selected from polyethylene resin, polypropylene resin, and polystyrene resin. .

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