JP4549467B2 - Process for producing ethylene-vinyl alcohol copolymer resin composition - Google Patents

Description

【０１１３】
【表２】

【０１１４】
【表３】

以上のとおり、本発明によれば、下記の利点が得られる。
（１）フィーダーのホッパー内のブリッジの発生を防止し、押出機へ安定して原料樹脂を供給できる。
（２）ペレットの表面水分量が少ないので、ホッパー下部で水蒸気が発生せず、原料ペレットの融着も発生しない。
（３）押出機への原料ペレットの供給が安定しているので、酸・金属塩などの添加量が安定であり、熱安定性が低下することもない。
【０１１５】
【発明の効果】
以上説明したとおり、本発明のエチレン−ビニルアルコール共重合体(EVOH)樹脂組成物の製造方法は、ＥＶＯＨ樹脂を含水状態で溶融混練する方法であって、前記樹脂のペレット全体の含水率を０．５〜７０重量％の範囲かつ前記ペレットの表面水の水分率を１０重量％未満として押出機に前記ペレットを供給することにより、効率良く押出機に供給することができる。
【図面の簡単な説明】
【図１】本発明方法の一実施形態の概略工程図を示す説明図である。
【図２】本発明方法で用いる一実施形態のホッパー・フィーダーの部分切り欠き概略図である。
【符号の説明】
１ 原料供給部
２，４，６ フルフライトスクリュー部
３，５ 逆フライトスクリュー部
７ ベントシリンダー部
８ 微量成分添加部
９ 温度センサー
１０ シリンダバレル
１１ 吐出口
２０ ２軸押出機
３０ ホッパー・フィーダー
３１ ホッパー
３２ 蓋
３３ レベルスイッチ
３４ 攪拌装置
３５ 架台
３６ モーター
３７ スクリュー
３８ バレル[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a resin composition by supplying water-containing ethylene-vinyl alcohol copolymer (hereinafter also referred to as “EVOH”) resin pellets to an extruder.
[0002]
[Prior art]
Ethylene-vinyl alcohol copolymers are widely used for food packaging because of their high gas barrier properties and excellent oil / organic solvent resistance, fragrance retention, transparency, and the like. For food packaging, various molding methods such as films by extrusion molding, bottles by blow molding, and various packs by vacuum molding are employed. In these various molding methods, resin pellets must be supplied to an extruder and the melting temperature must be 200 ° C. or higher. If the thermal stability of the polymer is not improved, the polymer will deteriorate during melt molding. In addition, fish eyes and bumps occur, which causes the quality of the product to deteriorate. Therefore, it is necessary to remove the saponification catalyst residue contained at the time of resin manufacture from a polymer, or to add a heat stabilizer.
[0003]
Conventionally, in order to remove the saponification catalyst residue contained in the resin production from the polymer, the resin pellets are put in a washing container, brought into contact with a washing liquid (water) in a solid state, and extracted from the inside of the resin pellets by diffusion to the outside. (Japanese Patent Publication No. 55-19242). In addition, in order to add a heat stabilizer in the polymer, the resin pellets were placed in an acid treatment vessel and contacted with an acid aqueous solution in a solid state to impregnate or adsorb the acid inside the resin pellets (Japanese Patent Publication No. 55-19242). Issue gazette).
[0004]
However, the conventional method has a large amount of water adhering to the resin, and in order to remove this, hot air drying using a dryer for a long time is necessary, and the operation is complicated.
[0005]
As a method of obtaining EVOH pellets added with trace components as shown above,
(1) A method of spraying an aqueous solution of a trace component onto EVOH pellets, mixing with a Henschel mixer and drying (Japanese Patent Laid-Open No. 55-12108),
(2) A method of mixing powdery trace components into EVOH pellets and dry blending with a super mixer (Japanese Patent Laid-Open No. 57-34148),
(3) A method in which EVOH pellets are immersed in an aqueous solution containing a trace amount of components, dried and then dried (Japanese Patent Laid-Open No. 64-66262),
(4) A method of adjusting the water content of EVOH pellets to 20 to 80% by weight and then contacting with an aqueous solution of at least one compound selected from the group consisting of boron compounds, acetates and phosphate compounds (WO99 / 05213) Etc.) are known.
[0006]
However, in the addition method (1) or (2), the uniformity of trace components in the EVOH pellets is insufficient, and it is difficult to control the addition amount, so it is difficult to obtain a stable quality product. It is. The method (3) or (4) has an advantage that it is easy to control the amount of trace components contained in the EVOH pellets by adjusting the solution concentration. However, EVOH pellets treated by this method have a large motor torque and torque fluctuation in the extruder when they are molded by melt extrusion. Therefore, it is usually necessary to add a lubricant to the resin composition comprising EVOH during extrusion. It was. However, since a resin composition comprising EVOH is suitably used for food packaging applications and the like, the addition of such a lubricant is not necessarily preferable from the viewpoint of hygiene, and therefore reduction or elimination of the lubricant has been desired.
[0007]
The EVOH pellets treated by the method (3) or (4) usually cut strands obtained by precipitating a methanol solution of EVOH after saponification into a coagulation bath composed of a water / methanol mixed solution. Can be obtained. However, EVOH having an ethylene content of less than 20 mol% and / or EVOH having a saponification degree of less than 95% are less likely to precipitate strands in the coagulation bath, and are likely to cause cut mistakes and fine powders. It is difficult to stably produce pellets. In some cases, strand precipitation cannot be performed, and paste-like EVOH is precipitated as a crumb-like material solidified in an irregular shape. However, when the crumb-like precipitate is treated by the method (3) or (4), it is difficult to mix the trace components homogeneously, and a stable quality product cannot be obtained.
[0008]
On the other hand, even when EVOH has an ethylene content of 20 mol% or more and a saponification degree of 95% or more, strand precipitation becomes unstable when strand precipitation is performed at a high speed in order to improve production efficiency. Stable production of pellets became difficult, and the processing method (3) or (4) failed to obtain a product with stable quality.
[0009]
Furthermore, from the viewpoint of the manufacturing process, in the case of a treatment method in which conventional EVOH pellets are immersed in a treatment liquid containing an acidic substance and / or a metal salt, a treatment bath or treatment tower for immersing the pellets is provided. The treatment liquid used in such treatment baths or towers is either disposable or recovered after use of EVOH because it consumes acidic substances and / or metal salts, so that an appropriate amount can be obtained. Of acid substances and / or metal salts must be added again.
[0010]
Disposing of the treatment liquid is not preferable from the viewpoint of environmental impact, and is usually discarded through wastewater treatment equipment. In addition, when recovering and reusing the processing liquid, in order to supply a stable quality product, there is a facility for re-adding acidic substances and / or metal salts and impurities such as oligomers in the processing liquid. Removal equipment was required.
[0011]
As described above, the conventional method has a problem in that it requires a large processing apparatus and a long-time processing, and the manufacturing cost is high.
[0012]
[Problems to be solved by the invention]
In order to solve the above-mentioned conventional problems, the present inventors efficiently remove moisture from a water-containing and molten ethylene-vinyl alcohol copolymer resin using an extruder, and efficiently add additives to the resin. As a result of studying a method for producing an ethylene-vinyl alcohol copolymer resin with a low production cost, when the water-containing ethylene-vinyl alcohol copolymer resin pellets are supplied to the extruder, the amount of water landing on the surface of the resin pellets When there are many, for example, pellets form bridges in the hopper, blocks form in the feeder, water vapor is generated from the extruder, and the water-containing ethylene-vinyl alcohol copolymer resin pellets are fused together. I found various problems.
[0013]
As a specific problem, a bridge is generated in the hopper of the feeder, resulting in poor supply of the raw material resin to the extruder. Or the surface water isolate | separated within the feeder is supplied to an extruder, water vapor | steam generate | occur | produces in the lower part of a hopper, the fusion | melting of a raw material pellet will generate | occur | produce, and it will become a poor supply of the raw material resin to an extruder. Especially in the case of hydrous EVOH, since the melting point is lowered, it is easily affected, and the pellets are easily fused at the lower part of the hopper, and the supply amount to the extruder fluctuates as an effect on quality due to poor supply. In addition, the amount of acid / metal salt added becomes unstable, causing problems such as a decrease in thermal stability.
[0014]
In order to solve the above-mentioned conventional problems, the present invention controls the amount of water landing on the surface of the resin pellets to a predetermined value or less when supplying the water-containing ethylene-vinyl alcohol copolymer resin pellets to the extruder. An object of the present invention is to provide a method for efficiently supplying to an extruder.
[0015]
[Means for solving problems]
  In order to achieve the above object, the method for producing an ethylene-vinyl alcohol copolymer (EVOH) resin composition of the present invention comprises melt-kneading an ethylene-vinyl alcohol copolymer resin in a water-containing state.To produce an ethylene-vinyl alcohol copolymer resin compositionA method of supplying the pellets to an extruder with a moisture content of the whole resin pellet in the range of 0.5 to 70% by weight and a moisture content of the surface water of the pellets of less than 10% by weight.The water content of the resin immediately after being discharged from the extruder is 5 to 40% by weight.It is characterized by that.
[0016]
In the said method, since the supply method of a pellet can supply stably the pellet to an extruder using a quantitative feeder, it is preferable.
[0017]
Moreover, in the said method, when an additive is melt-kneaded in a water-containing state, it is preferable from being able to mix uniformly.
[0018]
Moreover, in the said method, it is preferable that the resin melting temperature in an extruder is the range of 70-170 degreeC.
[0019]
Moreover, in the said method, it is preferable that the ethylene content of an ethylene-vinyl alcohol copolymer is the range of 3-70 mol%.
[0020]
Moreover, in the said method, it is preferable that the saponification degree of an ethylene-vinyl alcohol copolymer is the range of 80 mol%-100 mol%.
[0021]
  Moreover, in the said method, the moisture content of resin immediately after discharging from an extruder is 5 to 40 weight%.The
[0022]
Moreover, in the said method, it is preferable to supply deficient water in an extruder or to remove excess water so that the moisture content of resin immediately after discharging from an extruder may be 5 to 40 weight%.
[0023]
Moreover, in the said method, it is preferable to add at least 1 sort (s) of additive chosen from carboxylic acid, a boron compound, a phosphoric acid compound, an alkali metal salt, and an alkaline-earth metal salt to a water-containing molten resin in an extruder.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described with reference to the drawings. FIG. 1 is an explanatory view showing a schematic process chart of an embodiment of the method of the present invention. Water-containing EVOH is supplied from the raw material supply unit 1 of the twin-screw extruder 20. The hydrous EVOH in a molten or semi-molten state is fed forward by the full flight screw part 2, kneaded by the reverse flight screw part 3, and excess moisture is desorbed and adjusted in the vent cylinder part 7. Then, it sends toward the front by the full flight screw part 4, and a predetermined amount of additive is added from the trace component addition part 8. FIG. Then, it kneads | mixes with the reverse flight screw part 5, passes through the full flight screw part 6, and is discharged from the discharge outlet 11. FIG. Pelletization is performed downstream of the discharge port 11. Reference numeral 9 denotes a temperature sensor for detecting and controlling the temperature of the EVOH. Reference numeral 10 denotes a cylinder barrel.
[0025]
Next, FIG. 2 is a partially cutaway schematic view of a hopper feeder according to an embodiment used in the method of the present invention. The hopper feeder 30 includes a hopper 31 for storing resin pellets and a lid 32 thereof, a level switch 33 for detecting the abundance of the resin pellets, a stirring device 34 for preventing bridging of the resin pellets, and a screw 37 for rotating the screw 37. It consists of a motor 36, an extruder barrel 38, and a mount 35.
[0026]
EVOH used in the present invention is preferably one obtained by saponifying an ethylene-vinyl ester copolymer. From the viewpoint of obtaining a molded article having an ethylene content of 3 to 70 mol% and excellent gas barrier properties and melt moldability, it is preferably 10 to 60 mol%, more preferably 20 to 55 mol%, and most preferably Is preferably 25 to 55 mol%. Furthermore, the saponification degree of the vinyl ester component is 80 mol% or more, and from the viewpoint of obtaining a molded article having excellent gas barrier properties, it is preferably 95 mol% or more, particularly preferably 99 mol% or more.
[0027]
On the other hand, EVOH having an ethylene content of 3 to 20 mol% is suitably used as EVOH imparted with water solubility, and such an EVOH aqueous solution is excellent in barrier properties and film formability and is used as an excellent coating material.
[0028]
Further, EVOH having a saponification degree of 80 to 95 mol% is suitably used for improving melt moldability. Such EVOH can be used alone, but an embodiment in which EVOH is blended with EVOH having a saponification degree exceeding 99 mol% is also suitable.
[0029]
However, from the viewpoint of the production process, EVOH having an ethylene content of 3 to 20 mol% and EVOH having a saponification degree of 80 to 95 mol% are both prepared by using a methanol solution of such EVOH as in the conventional method. It was difficult to extrude and precipitate in a coagulation bath in the form of a strand, it was difficult to produce stable pellets, and it was also difficult to uniformly contain acidic substances and metal salts in the pellets. The significance of the present invention is great from the viewpoint of enabling stable production of pellets even for such EVOH.
[0030]
When the ethylene content of EVOH is less than 3 mol%, melt moldability is poor, and the water resistance, hot water resistance, and gas barrier properties under high humidity may be reduced. On the other hand, when it exceeds 70 mol%, barrier properties, printability and the like are insufficient. On the other hand, when the degree of saponification is less than 80 mol%, the barrier properties, coloring resistance and moisture resistance are unsatisfactory.
[0031]
The EVOH production method will be specifically described below. Polymerization of ethylene and vinyl ester is not limited to solution polymerization, and may be any of solution polymerization, suspension polymerization, emulsion polymerization, and bulk polymerization. Moreover, any of a continuous type and a batch type may be sufficient. An example of polymerization conditions for batch solution polymerization is shown below.
[0032]
Solvent: Alcohols are preferred, but other organic solvents (such as dimethyl sulfoxide) that can dissolve ethylene, vinyl ester and ethylene-vinyl ester copolymer can be used. As alcohols, methyl alcohol, ethyl alcohol, propyl alcohol, n-butyl alcohol, t-butyl alcohol and the like can be used, and methyl alcohol is particularly preferable.
[0033]
Catalyst: 2,2-azobisisobutyronitrile, 2,2-azobis- (2,4-dimethylvaleronitrile), 2,2-azobis- (4-methoxy-2,4-dimethylvaleronitrile), 2 , 2-azobis- (2-cyclopropylpropionitrile) and other azonitrile initiators and isobutyryl peroxide, cumylperoxyneodecanoate, diisopropylperoxycarbonate, di-n-propylperoxydicarbonate, t Organic peroxide initiators such as butyl peroxyneodecanoate, lauroyl peroxide, benzoyl peroxide, and t-butyl hydroperoxide can be used.
[0034]
Vinyl esters; vinyl acetate and fatty acid vinyl esters (such as vinyl propionate and vinyl pivalate) can also be used. Moreover, EVOH can contain 0.0002-0.2 mol% of vinyl silane compounds as a copolymerization component. Here, examples of the vinylsilane compound include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri (β-methoxy-ethoxy) silane, and γ-methacryloxypropylmethoxysilane. Of these, vinyltrimethoxysilane and vinyltriethoxysilane are preferably used.
(1) Temperature; 20 to 90 ° C, preferably 40 to 70 ° C.
(2) Time: 2 to 15 hours, preferably 3 to 11 hours.
(3) Polymerization rate: 10 to 90%, preferably 30 to 80%, relative to the charged vinyl ester.
(4) Resin content in the solution after polymerization; 5 to 85%, preferably 20 to 70%.
(5) Ethylene content in the copolymer; 3-70 mol%. Preferably 10-60 mol%, more preferably 20-55 mol%, optimally 25-55 mol%
In addition to ethylene and vinyl esters, monomers that can be copolymerized with these, for example, α-olefins such as propylene, isobutylene, α-octene, α-dodecene; acrylic acid, methacrylic acid, crotonic acid, maleic acid, itacone Unsaturated acids such as acids or their anhydrides, salts, mono- or dialkyl esters, etc .; Nitriles such as acrylonitrile and methacrylonitrile; Amides such as acrylamide and methacrylamide; Ethylene sulfonic acid, allyl sulfonic acid, methallyl sulfone An olefin sulfonic acid such as an acid or a salt thereof; alkyl vinyl ethers, vinyl ketone, N-vinyl pyrrolidone, vinyl chloride, vinylidene chloride and the like may be present in a small amount.
[0035]
After polymerization for a predetermined time, after reaching a predetermined polymerization rate, a polymerization inhibitor is added if necessary, and unreacted ethylene gas is removed by evaporation, and then unreacted vinyl ester is driven out. As a method for driving off the unreacted vinyl ester from the ethylene-vinyl ester copolymer from which ethylene has been removed by evaporation, for example, the copolymer solution is continuously fed at a constant rate from the upper part of the column filled with Raschig rings, A method of blowing an organic solvent vapor such as methanol from the bottom, distilling a mixed vapor of an organic solvent such as methanol and unreacted vinyl ester from the top of the tower, and taking out the copolymer solution from which the unreacted vinyl ester has been removed from the bottom of the tower, etc. Is adopted.
[0036]
An alkali catalyst is added to the copolymer solution from which unreacted vinyl ester has been removed to saponify the vinyl ester component in the copolymer. The saponification method can be either continuous or batch. As the alkali catalyst, sodium hydroxide, potassium hydroxide, alkali metal alcoholate or the like is used. For example, the saponification conditions in the case of a batch type are as follows.
(1) Concentration of the copolymer solution: 10 to 50%
(2) Reaction temperature: 30 to 65 ° C
(3) Amount of catalyst used: 0.02 to 1.0 equivalent (per vinyl ester component)
(4) Time: 1-6 hours
The EVOH after the reaction is preferably neutralized as necessary.
[0037]
The present invention is a method in which EVOH is melt-kneaded in a water-containing state, and the water content of the resin pellets as a whole is in the range of 0.5 to 70% by weight and the water content of the surface water of the pellets is less than 10% by weight. Pellets are supplied to the extruder.
[0038]
The shape of the pellets supplied to the extruder is not particularly limited, columnar pellets obtained by cutting the strands precipitated in the coagulation bath, and meteorites obtained by directly cutting molten resin Shaped pellets can be used. Usually, the former columnar pellet is preferably used.
[0039]
The lower limit of the moisture content of the entire EVOH pellets before being put into the extruder is 0.5% by weight or more. The water content is more preferably 5% by weight or more, and more preferably 7% by weight or more. Moreover, the upper limit of the moisture content of the entire EVOH pellets before being put into the extruder is 70% by weight or less. The water content is preferably 60% by weight or less, and more preferably 50% by weight or less. Since the moisture content of the entire EVOH pellets before being put into the extruder is in such a range, it becomes possible to obtain molten EVOH at a temperature lower than the melting point of the dried EVOH in the extruder. It is possible to suppress the thermal degradation of EVOH in and to improve the extrusion stability.
[0040]
When the moisture content of the entire EVOH pellets before being put into the extruder is less than 0.5% by weight, the effect of suppressing the thermal deterioration of EVOH in the extruder may be insufficient. When the water content exceeds 70% by weight, the resin and water contained in the resin may easily cause phase separation in the resin composition made of EVOH.
When phase separation occurs between the resin and water contained in the resin, the resin surface becomes wet and friction increases, which may cause bridging in the extruder hopper. There is a risk of adversely affecting the productivity of waste pellets.
[0041]
It does not specifically limit as a method of adjusting the moisture content of EVOH before thrown in in an extruder. In increasing the water content, there are a method of spraying water on the resin, a method of immersing the resin in water, a method of contacting the resin with water vapor, and the like. Further, when the moisture content is reduced, an appropriate drying method may be used. For example, a method of drying using a fluid hot air dryer or a stationary hot air dryer is mentioned, but from the viewpoint of reducing dry spots. It is preferable to use a fluid hot air dryer. Furthermore, from the viewpoint of suppressing thermal degradation, the drying temperature is preferably 120 ° C. or lower.
[0042]
Moreover, the moisture content of the surface water of the pellets thrown into the extruder in the present invention is less than 10% by weight. When the water content of the surface water is 10% by weight or more, the surface water separated by the feeder falls into the extruder, water vapor is generated at the lower part of the hopper, and fusion of the raw material pellets easily occurs. In particular, the EVOH of the present invention is problematic because it often contains water in the resin and has a low melting point, and is easier to fuse than ordinary dry EVOH. The surface water is preferably 8% by weight or less.
[0043]
A columnar pellet obtained by cutting a strand on which an EVOH solution is precipitated in a coagulation bath usually holds a large amount of surface water, but the method for removing the surface water from such a pellet is not particularly limited. Besides the method using a centrifuge, the surface water can be removed by hot air drying. Among these, a method using a centrifugal separator is preferable because it can prevent deterioration and fusion due to heat and can quickly remove moisture.
[0044]
Such EVOH pellets are fed into the extruder from the hopper portion. At this time, it is preferable to quantitatively supply pellets to the extruder using a quantitative feeder from the lower part of the hopper. Specifically, a quantitative feeder using a uniaxial screw is preferable. By supplying quantitatively, even when carboxylic acid, metal salt, or the like is added in the extruder, the addition amount is stabilized, and as a result, a resin having good thermal stability can be obtained.
[0045]
The resin temperature in the extruder is preferably 70 to 170 ° C. When the resin temperature is less than 70 ° C., EVOH may not be completely melted. Further, when at least one selected from carboxylic acid, boron compound, phosphoric acid compound, alkali metal salt and alkaline earth metal salt is added, the effect of improving the dispersibility may be insufficient. Preferably it is 80 degreeC or more, More preferably, it is 90 degreeC or more. In addition, when the resin temperature exceeds 170 ° C., EVOH may be easily subjected to thermal deterioration. Furthermore, when at least one selected from carboxylic acid, boron compound, phosphoric acid compound, alkali metal salt and alkaline earth metal salt is added as an aqueous solution, if the resin temperature exceeds 170 ° C., the evaporation of moisture becomes intense. Therefore, it may be difficult to mix EVOH and the aqueous solution at a suitable aqueous solution concentration. Preferably it is 150 degrees C or less, More preferably, it is 130 degrees C or less. The method for adjusting the resin temperature is not particularly limited, but a method for suitably setting the temperature of the cylinder in the extruder is particularly preferable.
[0046]
In the present invention, the resin temperature refers to the temperature detected by a temperature sensor installed in the extruder cylinder, and the detected location indicates the temperature near the discharge port at the tip of the extruder.
[0047]
In this invention, the saponification catalyst residue contained at the time of manufacture of EVOH can be removed. Specifically, the EVOH resin can be supplied to the extruder, the cleaning liquid can be injected from at least one position of the extruder, the resin can be cleaned, and the cleaning liquid can be discharged from at least one position downstream from the injection portion.
[0048]
In the present invention, the saponification catalyst residue contained in EVOH supplied to the extruder is preferably an alkali metal ion.
[0049]
The content of alkali metal ions contained in EVOH supplied to the extruder is preferably in the range of 0.1 to 5% by weight in terms of metal. More preferably, it is 0.2% by weight or more, and further preferably 0.5% by weight or more. Further, it is more preferably 4% by weight or less, and further preferably 3% by weight or less. If it is less than 0.1% by weight, the conventional cleaning method can be manufactured in a sufficiently small space, and the manufacturing method of the present invention is not effective. On the other hand, if it exceeds 5% by weight, an extruder having a large L / D is required to perform sufficient washing, and this is not preferable because it increases costs.
[0050]
Moreover, it is preferable that the alkali metal ion contained in EVOH after washing | cleaning in this invention is 0.05 weight% or less in conversion of a metal. More preferably, it is 0.04 weight% or less, More preferably, it is 0.03 weight% or less. When it exceeds 0.05% by weight, the thermal stability of EVOH deteriorates, which is not preferable.
[0051]
The cleaning solution used in the present invention is not particularly limited as long as it can remove the saponification catalyst residue, but is preferably an aqueous solution of an acid having a pKa of 3.5 or more at 25 ° C. When an acid aqueous solution having a pKa of less than 3.5 at 25 ° C. is used, the coloring resistance and interlayer adhesion of EVOH may be unsatisfactory.
As such an acid having a pKa of 3.5 or more, a carboxylic acid is preferable, and acetic acid is particularly preferably used from the viewpoint of cost and the like. The acetic acid concentration when using an acetic acid aqueous solution is preferably 0.01 to 10 g / liter, more preferably 0.1 to 2 g / liter.
[0052]
The injection amount of the cleaning liquid is preferably 0.1 to 100 liters per kg of the resin input weight.
[0053]
The injection of the cleaning liquid is not particularly limited as long as it can inject the cleaning liquid into the extruder, and examples thereof include a method of press-fitting using a plunger pump or the like.
The discharge of the cleaning liquid is not particularly limited as long as it is disposed downstream of the injection unit and can discharge the liquid from the extruder, and a dehydration slit or a dehydration hole is preferable. A plurality of injection parts or a plurality of discharge parts may be arranged.
[0054]
Moreover, in this invention, after performing the said washing | cleaning, it is also preferable to dehydrate or deaerate from the water-containing EVOH in an extruder. Specifically, it is preferable to discharge at least one selected from liquid water and water vapor from at least one location of the extruder. Although it does not specifically limit as a discharge method here, The method of discharging from the dehydration slit, dehydration hole, or vent port arrange | positioned at the cylinder of the extruder is mentioned.
[0055]
Among these, a dehydration slit or a dehydration hole is preferable. Since these can be discharged with either liquid water or water vapor, it is possible to efficiently remove water from a resin with a high water content. In this respect, generally only water vapor is discharged. It is often more effective than a vent that cannot. Also, when water is discharged using the vent port, the resin tends to adhere to the vent port, and the adhered resin may deteriorate and mix into the extruder. Is preferred.
[0056]
As the vent port, a vacuum vent for removing water vapor under reduced pressure or an open vent for removing water vapor under normal pressure can be used.
[0057]
Moreover, when using a dehydration hole, molten resin may protrude from the hole, From this point, it is suitable to use a dehydration slit. As such a dewatering slit, a wedge wire dewatering slit or a screen mesh dewatering slit is preferable.
[0058]
In addition, the said dehydration means may be used independently, may use multiple things of the same kind, or may use it combining a thing of a different kind. For example, after removing water to some extent from a resin having a high water content using a dehydration slit, it is possible to further remove water from the vent port on the downstream side.
[0059]
The water content of the resin composition composed of EVOH immediately after discharge from the extruder is preferably 5 to 40% by weight, and particularly preferably 5 to 35% by weight. If the water content of the resin composition consisting of EVOH immediately after discharge from the extruder exceeds 40% by weight, in the resin composition consisting of EVOH, the resin and the water contained in the resin may easily cause phase separation, As a result, there is a risk that foaming is likely to occur after discharge from the extruder. Moreover, when the water content of the resin composition comprising EVOH immediately after discharge from the extruder is less than 5% by weight, the effect of suppressing deterioration of EVOH in the extruder due to heating may be insufficient, and the resulting EVOH pellets There is a risk that the coloring resistance of the toner becomes unsatisfactory.
[0060]
After washing in the extruder and dehydrating or degassing, at least one selected from carboxylic acid, boron compound, phosphoric acid compound, alkali metal salt and alkaline earth metal salt can be added alone. According to the embodiment, EVOH is formed by adding a plurality of compounds selected from carboxylic acid, boron compound, phosphoric acid compound, alkali metal salt and alkaline earth metal salt in the preferred range shown below. Various performances of the resin composition pellets can be improved.
[0061]
Addition of carboxylic acid to the resin composition pellet made of EVOH of the present invention is preferable from the viewpoint of improving thermal stability. As said carboxylic acid, it is preferable that pKa in 25 degreeC is 3.5 or more. When a carboxylic acid having a pKa of less than 3.5 at 25 ° C. is added, it is difficult to control the pH of the resin composition comprising EVOH, and the coloration resistance and interlayer adhesion may be unsatisfactory. Examples of the carboxylic acid include oxalic acid, succinic acid, benzoic acid, citric acid, acetic acid, lactic acid, and the like. From the viewpoint of cost and the like, it is preferable to use acetic acid or lactic acid.
[0062]
The content of the carboxylic acid in the dry resin composition pellet made of EVOH of the present invention is preferably 10 to 5000 ppm. If the carboxylic acid content is less than 10 ppm, coloring may occur during melt molding, and if it exceeds 5000 ppm, interlayer adhesion may be insufficient. The lower limit of the carboxylic acid content is preferably 30 ppm or more, and more preferably 50 ppm or more. The upper limit of the carboxylic acid content is preferably 1000 ppm or less, and more preferably 500 ppm or less.
[0063]
Moreover, it is preferable from a viewpoint of thermal stability improvement to add a phosphoric acid compound with respect to the resin composition pellet which consists of EVOH of this invention. The content of the phosphoric acid compound in the dry resin composition pellet made of EVOH of the present invention is preferably 1 to 1000 ppm in terms of phosphate radical, and coloring of the molded product by adding the phosphoric acid compound in an appropriate range It is also possible to suppress the occurrence of gels and blisters. The above improvement effect due to the addition of the phosphoric acid compound is particularly remarkable at the time of long-run molding using a resin composition pellet made of EVOH and at the time of recovery of the molded product. Examples of the phosphoric acid compound include, but are not limited to, various acids such as phosphoric acid and phosphorous acid and salts thereof. The phosphate may be contained in any form of primary phosphate, secondary phosphate, and tertiary phosphate, and the cation species is not particularly limited, but alkali metal salts An alkaline earth metal salt is preferred. Among these, it is preferable to add the phosphoric acid compound in the form of sodium dihydrogen phosphate, potassium dihydrogen phosphate, disodium hydrogen phosphate, or dipotassium hydrogen phosphate.
[0064]
The content of the phosphate compound is preferably at least 10 ppm, more preferably at least 30 ppm, and the upper limit is preferably at most 500 ppm, more preferably at most 300 ppm in terms of phosphate radical. By containing the phosphoric acid compound in such a range, a resin composition pellet made of EVOH with less coloring and less gelation can be obtained. When the content of the phosphoric acid compound is less than 1 ppm, there is a possibility that coloring during melt molding becomes intense. In particular, since the tendency is remarkable when the heat histories are accumulated, a molded product obtained by molding the resin composition pellet may be poor in recoverability. Moreover, when content of a phosphoric acid compound exceeds 1000 ppm, there exists a possibility that the gel of a molded product may occur easily.
[0065]
The resin composition pellet made of EVOH of the present invention preferably contains a boron compound from the viewpoint of improving thermal stability and improving mechanical properties (Japanese Patent Publication No. 49-20615). When a boron compound is added to a resin composition comprising EVOH, it is considered that a chelate compound is formed between EVOH and the boron compound. By using such EVOH, the thermal stability is improved compared to ordinary EVOH, mechanical It is possible to improve the properties.
[0066]
Examples of the boron compound include, but are not limited to, boric acids, boric acid esters, borates, borohydrides, and the like. Specific examples of boric acids include orthoboric acid, metaboric acid, and tetraboric acid. Examples of boric acid esters include triethyl borate and trimethyl borate. Examples include alkali metal salts of acids, alkaline earth metal salts, and borax. Of these compounds, orthoboric acid (simply expressed as boric acid) is preferable.
[0067]
The content of the boron compound in the dry resin composition pellet made of EVOH of the present invention is preferably 20 to 2000 ppm, more preferably 50 to 1000 ppm in terms of boron. If it is less than 10 ppm, the effect of improving the thermal stability due to the addition of the boron compound may not be obtained, and if it exceeds 2000 ppm, gelation tends to occur and moldability may be deteriorated.
[0068]
By including an alkali metal salt in the resin composition pellet made of EVOH of the present invention, interlayer adhesion and compatibility can be effectively improved.
As for the addition amount of the alkali metal salt in the dry resin composition pellet which consists of EVOH of this invention, 5-5000 ppm is preferable in conversion of an alkali metal element. More preferably, it is 20-1000 ppm, More preferably, it is 30-750 ppm. Examples of the alkali metal include lithium, sodium, and potassium, and examples of the alkali metal salt include aliphatic monovalent metal carboxylates, aromatic carboxylates, phosphates, and metal complexes. Examples thereof include sodium acetate, potassium acetate, sodium phosphate, lithium phosphate, sodium stearate, potassium stearate, sodium salt of ethylenediaminetetraacetic acid, and the like. Of these, sodium acetate, potassium acetate, and sodium phosphate are preferred.
[0069]
It is also preferable to add an alkaline earth metal salt to the resin composition pellet made of EVOH of the present invention. When the alkaline earth metal salt is added, the effect of improving the color resistance is slightly reduced, but the die adhesion amount of the molding machine of the thermally deteriorated resin is further reduced at the time of melt molding using the resin composition pellets. It is possible. The alkaline earth metal salt is not particularly limited, and examples thereof include magnesium salt, calcium salt, barium salt, and beryllium salt. Magnesium salt and calcium salt are particularly preferable. The anion species of the alkaline earth metal salt is not particularly limited, but an acetate anion and a phosphate anion are preferable.
[0070]
The content of the alkaline earth metal in the dry resin composition pellet made of EVOH of the present invention is preferably 10 to 1000 ppm, more preferably 20 to 500 ppm in terms of metal. If the content of alkaline earth metal is less than 10 ppm, the effect of improving the long run property may be insufficient, and if it exceeds 1000 ppm, coloring during resin melting may be severe.
[0071]
In including at least one selected from the carboxylic acid, boron compound, phosphoric acid compound, alkali metal salt and alkaline earth metal salt shown above in the resin composition pellet made of EVOH, the ethylene content is 3 to 70 mol%. In addition, at least one selected from carboxylic acid, boron compound, phosphoric acid compound, alkali metal salt and alkaline earth metal salt can be added to EVOH having a saponification degree of 80 mol% or more in an extruder. By adding at least one selected from carboxylic acid, boron compound, phosphate compound, alkali metal salt and alkaline earth metal salt in the extruder, carboxylic acid, boron compound, phosphate compound, alkali metal with respect to EVOH At least one selected from a salt and an alkaline earth metal salt is blended, and at least one selected from a carboxylic acid, a boron compound, a phosphoric acid compound, an alkali metal salt and an alkaline earth metal salt is very good with respect to EVOH Can be kneaded with uniform uniformity. By adopting such a configuration, the motor torque of the extruder at the time of melt molding and its torque fluctuation are small, the extrusion stability, the coloration resistance and the long run property are excellent, and the generation of gels and blisters and the die adhesion amount are low. It becomes possible to obtain the resin composition pellet which becomes. In addition, in this invention, in adding at least 1 sort (s) chosen from carboxylic acid, a boron compound, a phosphoric acid compound, an alkali metal salt, and an alkaline-earth metal salt to EVOH in an extruder, to the extruder of the said carboxylic acid etc. It is preferable that the feed position is added at a position where EVOH in the extruder is in a molten state in order to sufficiently exhibit the effects of the present invention. In particular, it is preferable to add the additive to water-containing and molten EVOH.
[0072]
The extruder preferably has a kneading part, and in particular, the addition position of the additive is preferably the kneading part of the extruder because the additive is easily mixed homogeneously.
[0073]
Moreover, it is also possible to use the metal salt described in the 4th period of a periodic table as metal salts other than the said alkali metal salt and alkaline-earth metal salt.
[0074]
The addition form of at least one selected from carboxylic acid, boron compound, phosphoric acid compound, alkali metal salt and alkaline earth metal salt is not particularly limited. Examples include a method of adding as a dry powder in an extruder, a method of adding in a paste impregnated with a solvent, a method of adding in a suspended state in a liquid, a method of adding as a solution by dissolving in a solvent, etc. From the viewpoint of controlling the addition amount and uniformly dispersing at least one selected from carboxylic acid, boron compound, phosphoric acid compound, alkali metal salt and alkaline earth metal salt in EVOH, carboxylic acid, boron compound, A method in which at least one selected from phosphoric acid compounds, alkali metal salts and alkaline earth metal salts is dissolved in a solvent and added as a solution is particularly suitable. Such solvent is not particularly limited, but at least one kind of solubility selected from carboxylic acid, boron compound, phosphoric acid compound, alkali metal salt and alkaline earth metal salt, cost advantage, ease of handling, work environment From the viewpoint of safety and the like, water is preferable.
[0075]
A method for adding at least one selected from carboxylic acid, boron compound, phosphoric acid compound, alkali metal salt and alkaline earth metal salt to EVOH is not particularly limited. It is preferable to add at least one selected from carboxylic acid, boron compound, phosphoric acid compound, alkali metal salt and alkaline earth metal salt to the extruder from one or more places.
[0076]
When at least one selected from a carboxylic acid, a boron compound, a phosphoric acid compound, an alkali metal salt and an alkaline earth metal salt is added as a solution to EVOH, the dry weight of EVOH is 100 parts by weight relative to the EVOH. The lower limit of the addition amount of the solution is preferably 1 part by weight or more, more preferably 3 parts by weight or more, and particularly preferably 5 parts by weight or more. The upper limit of the amount of the solution added is preferably 50 parts by weight or less, more preferably 30 parts by weight or less, and more preferably 20 parts by weight or less with respect to 100 parts by weight of EVOH dry weight. Particularly preferred. When the amount of the solution added is less than 1 part by weight, the concentration of the solution generally increases, so at least one type selected from carboxylic acid, boron compound, phosphoric acid compound, alkali metal salt and alkaline earth metal salt is added. There is a risk that the effect of improving the dispersibility in the case will decrease. In addition, when it exceeds 50 parts by weight, it may be difficult to control the moisture content of EVOH, and in the resin composition comprising EVOH in the extruder, the resin and water contained in the resin may easily cause phase separation. There is.
[0077]
In the conventional treatment method in which EVOH is impregnated with a solution of an acidic substance and / or metal salt, it has been difficult to obtain a good quality product from the crumb-like precipitates of EVOH as described above. Therefore, even with respect to such a form of EVOH, at least one selected from carboxylic acid, boron compound, phosphoric acid compound, alkali metal salt and alkaline earth metal salt can be added homogeneously, and it consists of EVOH of stable quality. It is possible to obtain resin composition pellets.
[0078]
The method of pelletizing the resin composition comprising EVOH discharged from the extruder is not particularly limited, but there is exemplified a method of extruding the resin composition from a die into a strand into a coagulation bath and cutting it to an appropriate length. The From the viewpoint of easy handling of pellets, the diameter of the die is preferably 2 to 5 mmφ (φ is the diameter; the same applies hereinafter), and the strand is preferably cut to a length of about 1 to 5 mm.
[0079]
The obtained pellets are usually subjected to a drying process. The water content of the resin composition pellets comprising EVOH after drying is 1% by weight or less, and preferably 0.5% by weight or less. The drying method is not particularly limited, but a stationary drying method, a fluidized drying method, and the like are preferable, and a multi-step drying process in which several drying methods are combined may be employed. Among these, a method of drying by a fluidized drying method first and then drying by a stationary drying method is preferable.
[0080]
In the case of a treatment method in which conventional EVOH pellets are immersed in a treatment solution containing an acidic substance and / or a metal salt, the water content of the treated EVOH is usually about 40 to 70% by weight. However, the EVOH of the present invention is melted in an extruder, washed in the extruder as necessary, dehydrated or degassed, and then carboxylic acid, boron compound, phosphate compound, alkali metal salt and alkaline earth metal salt. In the case of a treatment method in which at least one selected from the above is added, the water content of the resin composition comprising EVOH immediately after discharge from the extruder can be arbitrarily adjusted, and the water content immediately after discharge from the extruder is preferably 5 -40% by weight. Therefore, it is possible to obtain pellets having a lower moisture content than the conventional method. Such pellets having a low water content are suitable from the viewpoint of reducing energy consumption in the drying process.
[0081]
In particular, pellets having a moisture content exceeding 40% by weight may cause fusion between the pellets when the drying temperature is 100 ° C. or higher. From this point of view as well, pellets having a low water content as described above can be obtained. After EVOH is melted in an extruder, washed in the extruder, dehydrated or degassed, carboxylic acid, boron compound, phosphate compound, alkali The treatment method of the present invention in which at least one selected from metal salts and alkaline earth metal salts is added is preferred.
[0082]
It is also possible to blend and melt-mold EVOH having different degrees of polymerization, ethylene content and saponification degree to the resin composition pellets made of EVOH obtained by the above method. In addition, the resin composition pellets include other plasticizers, stabilizers, surfactants, colorants, ultraviolet absorbers, antistatic agents, desiccants, crosslinking agents, metal salts, fillers, reinforcing agents such as various fibers. It is also possible to add an appropriate amount of etc. Since the resin composition pellets comprising EVOH of the present invention have a small motor torque of the extruder and its torque fluctuation and are excellent in extrusion stability, the amount of the lubricant used may be greatly reduced or the lubricant may be reduced depending on the embodiment. It is particularly preferable in that it can be not used. However, the use of a lubricant when molding a molded product using the pellets is arbitrary and is not limited.
[0083]
Moreover, it is also possible to mix | blend an appropriate quantity of thermoplastic resins other than EVOH in the range which does not inhibit the objective of this invention. Examples of thermoplastic resins include various polyolefins (polyethylene, polypropylene, poly 1-butene, poly 4-methyl-1-pentene, ethylene-propylene copolymers, copolymers of ethylene and α-olefins having 4 or more carbon atoms, polyolefins. And maleic anhydride copolymers, ethylene-vinyl ester copolymers, ethylene-acrylic ester copolymers, or modified polyolefins obtained by graft-modifying them with unsaturated carboxylic acids or their derivatives), various nylons (nylon -6, nylon-6,6, nylon-6 / 6,6 copolymer, etc.), polyvinyl chloride, polyvinylidene chloride, polyester, polystyrene, polyacrylonitrile, polyurethane, polyacetal, and modified polyvinyl alcohol resin.
[0084]
The obtained resin composition pellets comprising the EVOH of the present invention are molded into various molded bodies such as films, sheets, containers, pipes, fibers and the like by melt molding. These molded products can be pulverized and molded again for reuse. It is also possible to uniaxially or biaxially stretch films, sheets, fibers, and the like. As the melt molding method, extrusion molding, inflation extrusion, blow molding, melt spinning, injection molding and the like are possible. The melting temperature varies depending on the melting point of the copolymer, but is preferably about 150 to 270 ° C.
[0085]
As described above, the resin composition pellet made of EVOH of the present invention comprises at least one layer of a molded product such as the composition film or sheet of the present invention, in addition to the production of a resin molded product having only the resin composition as a single layer. Often used as a multilayer structure. As the layer structure of the multilayer structure, E / Ad / T, T / Ad / E / Ad, where E is the resin composition comprising EVOH of the present invention, Ad is the adhesive resin, and T is the thermoplastic resin. Although / T etc. are mentioned, it is not limited to this. Each layer may be a single layer or may be a multilayer according to circumstances.
[0086]
The thermoplastic resin used is linear low density polyethylene, low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, polypropylene, propylene-α-olefin copolymer. Polymers (α-olefins having 4 to 20 carbon atoms), homopolymers of olefins such as polybutene and polypentene or copolymers thereof, polyesters such as polyethylene terephthalate, polyester elastomers, polyamide resins such as nylon-6 and nylon-6,6 , Polystyrene, polyvinyl chloride, polyvinylidene chloride, acrylic resin, vinyl ester resin, polyurethane elastomer, polycarbonate, chlorinated polyethylene, chlorinated polypropylene, and the like. Among these, polypropylene, polyethylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, polyamide, polystyrene, and polyester are preferably used.
[0087]
When laminating EVOH and a thermoplastic resin, an adhesive resin may be used, and the adhesive resin in this case is preferably an adhesive resin made of carboxylic acid-modified polyolefin. The carboxylic acid-modified polyolefin is a modified olefin polymer containing a carboxyl group obtained by chemically (for example, addition reaction or graft reaction) bonding an ethylenically unsaturated carboxylic acid or its anhydride to an olefin polymer. Is preferred. Here, the olefin polymer is a polyolefin such as polyethylene (low pressure, medium pressure, high pressure), linear low density polyethylene, polypropylene, boribten, or the like, a comonomer (vinyl ester, unsaturated carboxylic acid) capable of copolymerizing the olefin and the olefin. A copolymer with an acid ester etc.), for example, an ethylene-vinyl acetate copolymer, an ethylene-acrylic acid ethyl ester copolymer and the like. Of these, linear low density polyethylene, ethylene-vinyl acetate copolymer (vinyl acetate content 5-55 wt%), ethylene-acrylic acid ethyl ester copolymer (acrylic acid ethyl ester content 8-35 wt. %), Linear low density polyethylene and ethylene-vinyl acetate copolymers are particularly preferred. Examples of the ethylenically unsaturated carboxylic acid or its anhydride include an ethylenically unsaturated monocarboxylic acid, its ester, an ethylenically unsaturated dicarboxylic acid, its mono or diester, and its anhydride. Among them, the ethylenically unsaturated dicarboxylic acid Anhydrides are preferred. Specific examples include maleic acid, fumaric acid, itaconic acid, maleic anhydride, itaconic anhydride, maleic acid monomethyl ester, maleic acid monoethyl ester, maleic acid diethyl ester, and fumaric acid monomethyl ester. Acid is preferred.
[0088]
The addition amount or graft amount (modification degree) of the ethylenically unsaturated carboxylic acid or its anhydride to the olefin polymer is 0.01 to 15% by weight, preferably 0.02 to 10% by weight, based on the olefin polymer. It is. The addition reaction and grafting reaction of the ethylenically unsaturated carboxylic acid or its anhydride to the olefin polymer can be obtained, for example, by radical polymerization in the presence of a solvent (such as xylene) or a catalyst (such as a peroxide). The melt index (MI) measured at 190 ° C according to D-1238-65T according to ASTM-D1238 of the carboxylic acid-modified polyolefin thus obtained is preferably 0.2 to 30 g / 10 min. Preferably it is 0.5-10 g / 10min. These adhesive resins may be used alone or as a mixture of two or more layers.
[0089]
In the present invention, the multilayer structure can be used in various shapes as it is, but in order to improve the physical properties of the multilayer structure, it is also preferable to perform a stretching treatment, fracture, pinhole, stretching unevenness, A stretched film or a stretched sheet that does not cause delamination or the like is obtained.
[0090]
The stretching may be either uniaxial stretching or biaxial stretching, and it is better in terms of physical properties to perform stretching as high as possible. In the present invention, a stretched film, a stretched sheet or the like that does not cause pinholes, cracks, stretch unevenness, delamination, or the like during stretching can be obtained.
[0091]
As the stretching method, in addition to a roll stretching method, a tenter stretching method, a tubular stretching method, a stretching blow method, and the like, a deep drawing method, a vacuum forming method, or the like having a high stretching ratio can be employed. In the case of biaxial stretching, both a simultaneous biaxial stretching method and a sequential biaxial stretching method can be employed. The stretching temperature is selected from the range of about 80 to 170 ° C, preferably about 100 to 160 ° C.
[0092]
Thus, after stretching is completed, heat setting is then performed. The heat setting can be carried out by a known means, and the heat treatment is performed at 80 to 170 ° C., preferably 100 to 160 ° C. for about 2 to 600 seconds while keeping the stretched film in a tension state. Further, the obtained stretched film can be subjected to cooling treatment, printing treatment, dry laminating treatment, solution or melt coating treatment, bag making processing, box processing, tube processing, split processing and the like as required.
[0093]
The shape of the multilayer structure thus obtained may be any shape, and examples thereof include films, sheets, tapes, bottles, pipes, filaments, and modified cross-section extrudates. In addition, the obtained multilayer structure may be subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry lamination treatment, solution or melt coating treatment, bag making processing, deep drawing processing, box processing, tube processing, split processing, etc. It can be performed. The film, sheet or container obtained as described above is useful as various packaging materials such as foods, pharmaceuticals, industrial chemicals and agricultural chemicals.
[0094]
In producing the multilayer structure shown above, another substrate is laminated on one side or both sides of a layer of a molded product such as a film or sheet obtained from the resin composition comprising EVOH of the present invention. As a laminating method, for example, a method in which a thermoplastic resin is melt-extruded into the molded product (film, sheet, etc.), and conversely, the resin composition and another thermoplastic resin are co-extruded into a base material such as a thermoplastic resin. , A method of co-injecting a resin composition comprising a thermoplastic resin and EVOH, and a molded product obtained from the resin composition comprising EVOH and a film or sheet of another substrate, an organic titanium compound, an isocyanate compound And a method of laminating using a known adhesive such as a polyester-based compound. Among them, a method of co-extrusion with other thermoplastic resins is preferably used. Since the resin composition comprising EVOH of the present invention is very excellent in interlayer adhesion, it is suitable for a co-extrusion resin composition and a co-extrusion multilayer structure using the same.
[0095]
The co-extrusion method of the composition of the present invention and the thermoplastic resin may be any of a multi-manifold merging method T-die method, a feed block merging method T-die method, and an inflation method.
[0096]
By subjecting the co-extruded multilayer structure thus obtained to secondary processing, various molded articles (films, sheets, tubes, bottles, etc.) can be obtained. Examples thereof include the following.
(1) A multilayer co-stretched sheet or film obtained by stretching a multilayer structure (such as a sheet or film) in a uniaxial or biaxial direction, or stretching and heat-treating in a biaxial direction.
(2) A multilayer rolled sheet or film obtained by rolling a multilayer structure (such as a sheet or film)
(3) Multilayer tray cup-shaped container by thermoforming such as multilayer structure (sheet or film) vacuum forming, pressure forming, vacuum pressure forming, etc.
(4) Bottles and cup-shaped containers by stretch blow molding from multi-layer structures (pipe, etc.)
There is no restriction | limiting in particular in such a secondary processing method, Well-known secondary processing methods (blow molding etc.) other than the above are also employable.
[0097]
The coextruded multilayer structure and the co-injection multilayer structure obtained in this way are less likely to generate gels and blisters and less likely to cause fish eyes and streaks during film formation. It is suitably used as a material for squeezed containers, cup-shaped containers, bottles and the like.
[0098]
【Example】
EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited to this Example. Hereinafter, “%” and “parts” are based on weight unless otherwise specified. In addition, all the water used ion-exchange water.
(1) Moisture content of surface water
The EVOH pellets used were an upper discharge type centrifuge H-130M manufactured by Kokusan Centrifuge Co., Ltd. having the following specifications. 10 kg of EVOH pellets were carried out for 5 minutes in a centrifuge with the following specifications. From the change in EVOH weight before and after centrifugation, the moisture content of EVOH surface water was determined using the following equation (Equation 1).
<Centrifuge specifications>
Model: H-130M
Name: Upper discharge centrifuge
Capacity: 107L (Diameter 914mm x Depth 430mm)
Material: SUS304
Rotation speed: 1000rpm (510G)
<Moisture content of surface water>
[0099]
(Equation 1)
Moisture content of surface water (% by weight) = (weight before centrifugation−weight after centrifugation) / weight before centrifugation × 100
(2) Measurement of moisture content
Take 20 g of water-containing EVOH as a sample in a well-dried weighing bottle and dry it with a hot air dryer at 120 ° C. for 24 hours. From the change in EVOH weight before and after drying, use The rate was determined.
[0100]
(Equation 2)
Water content (% by weight) = (weight before drying−weight after drying) / weight before drying × 100
(4) Quantification of added trace components
Quantification was performed according to the following method. The following “dry pellet” means a resin composition pellet made of EVOH to which at least one selected from carboxylic acid, boron compound, phosphoric acid compound, alkali metal salt and alkaline earth metal salt is added in an extruder. The product was obtained by drying at 100 ° C. for 15 hours using a fluid hot air dryer and then drying at 100 ° C. for 15 hours using a stationary hot air dryer.
(2-a) Determination of carboxylic acid content
20 g of dried pellets as a sample were put into 100 ml of ion-exchanged water and extracted by heating at 95 ° C. for 6 hours. The extract was neutralized with 1/50 N NaOH using phenolphthalein as an indicator, and the carboxylic acid content was quantified.
(2-b) Determination of alkali metal ions and alkaline earth metal ions
10 g of dried pellets as a sample were put into 50 ml of 0.01 N hydrochloric acid aqueous solution and stirred at 95 ° C. for 6 hours. The aqueous solution after stirring was quantitatively analyzed using ion chromatography. The column used was ICS-C25 manufactured by Yokogawa Electric Corporation, and the eluent was an aqueous solution containing 5.0 mM tartaric acid and 1.0 mM 2,6-pyridinedicarboxylic acid. For the determination, a calibration curve prepared with each metal chloride aqueous solution was used. Thus, the amount of alkali metal salt and the amount of alkaline earth metal in the dried pellets were obtained in metal equivalent amounts.
(2-c) Determination of boron compounds
The sample pellets are Na₂CO_ThreeThe aqueous solution was added and incinerated at 600 ° C. with a platinum crucible. The obtained sample was dissolved by adding hydrochloric acid, and the content of the boron compound was quantified in terms of boron by ICP emission spectroscopy.
(2-d) Determination of phosphate ion
10 g of dried pellets as a sample were put into 50 ml of 0.01 N hydrochloric acid aqueous solution and stirred at 95 ° C. for 6 hours. The aqueous solution after stirring was quantitatively analyzed using ion chromatography to determine the amount of phosphate ions. The column used was ICS-A23 manufactured by Yokogawa Electric Corporation, and the eluent was an aqueous solution containing 2.5 mM sodium carbonate and 1.0 mM sodium bicarbonate. For the determination, a calibration curve prepared with a phosphoric acid aqueous solution was used. From the amount of phosphate ions thus obtained, the content of the phosphorus compound was obtained in terms of phosphate radical.
(3) Raw material supply continuous test
A raw material supply continuous test was conducted using the following capacity type feeder shown in FIG.
The continuous test was conducted for 8 hours, and the time from the start of the test until the occurrence of defective extrusion was measured.
<Quantitative single-axis feeder>
Specifications: SVF-25 manufactured by Nippon Steel Works
Processing amount: 10kg / hr (capacity: 4-20kg / hr) Hopper: 30L
Drive: 0.4KW (3) Melt index (MI)
According to ASTM-D1238, a melt indexer was used, and measurement was performed under conditions of a temperature of 190 ° C. and a load of 2160 g.
(4) Single layer film formation test
Using an extruder with the following specifications, a single-layer film was formed of a resin composition made of EVOH, a film-forming sample of a resin composition pellet made of EVOH was prepared, and gels, blisters, and coloring were evaluated.
[0101]
The specifications of the extruder are as follows.
[0102]
Extruder GT-40-A Made by Plastic Engineering Laboratory Co., Ltd.
Type Single-screw extruder (non-vent type)
L / D 26
CR 3.5
40mm diameter
Screw single-flight full flight type, surface nitrided steel
Rotation speed 40rpm
Drive unit Sumitomo Heavy Industries, Ltd. DC motor SCR-DC218B Motor capacity DC7.5KW (rated 45A)
Heater 4 split type
Die width 300mm
Resin temperature in die 240 ° C
Take-up speed 10 m / min.
(4-b) Gel / Buts
Using the dried pellets as samples, EVOH monolayer film formation was carried out, and the gel-like irregularities of the film one hour after the start of film formation (about 100 μm or more that can be confirmed with the naked eye) were counted.²Converted to per. Judgment was made as follows according to the number of items.
A; Less than 20 B; 20 to 40 C; 40 to 60 D; 60 or more
(4-c) Coloring
A single layer film of EVOH was formed using the dry pellets as a sample, the film after 1 hour from the start of film formation was wound on a paper tube, and the degree of coloration of the film end face was determined with the naked eye and determined as follows. .
A: No coloring B: Slightly yellow C: Yellowing D: Intense coloring
[0103]
[Example 1]
A 45% methanol solution of an ethylene-vinyl acetate copolymer having an ethylene content of 32 mol% was charged into a saponification reactor, and a caustic soda / methanol solution (80 g / L) was added to the vinyl acetate component in the copolymer in an amount of 0. It added so that it might become 4 equivalent, and methanol was added and it adjusted so that a copolymer concentration might be 20%. The temperature was raised to 60 ° C., and the reaction was carried out for about 4 hours while blowing nitrogen gas into the reactor. After 4 hours, the reaction was stopped by neutralizing with acetic acid, and water corresponding to 55% by weight of the total methanol in the reactor was added, and EVOH having an ethylene content of 32 mol% and a saponification degree of 99.5% was added. A solution of methanol and water was obtained. The EVOH solution was extruded from a metal plate having a circular opening into water to precipitate a strand, and was cut to obtain a pellet having a diameter of about 3 mm and a length of about 5 mm. The obtained pellet was repeatedly drained by adding a large amount of water. Surface water was removed from 10 kg of the lysed pellets using a centrifuge. The surface moisture content of the obtained pellet was 0% by weight.
[0104]
EVOH having an ethylene content of 32 mol%, a saponification degree of 99.5 mol%, and a water content of 33 wt% is charged into the twin-screw extruder shown in FIG. From the trace component addition part (8) shown in FIG. 1, a treatment liquid comprising acetic acid / boric acid / sodium acetate / magnesium acetate / potassium dihydrogen phosphate aqueous solution was added. The input amount of EVOH per unit time is 10 kg / hr (including the weight of contained water), the input amount of the treatment liquid per unit time is 0.67 L / hr, and the composition of the treatment liquid is 4. This was an aqueous solution containing 3 g / L, boric acid 15 g / L, sodium acetate 4.6 g / L, magnesium acetate 3.0 g / L, and potassium dihydrogen phosphate 1.4 g / L. The specifications of the twin screw extruder are shown below. As a result of the raw material supply continuous test, no extrusion failure was observed after 8 hours of continuous operation.
<Raw material feeder>
Capacity type single axis feeder
Processing amount: 10 kg / hr (capacity: 4-20 kg / hr) Hopper: 30 L, drive: 0.4 KW <extruder>
Type Twin screw extruder
L / D 45.5
Diameter 30mmφ
Screw in the same direction, fully meshed
300 rpm
Motor capacity DC22KW
Heater 13 split type
Number of die holes 5 holes (3mmφ) Resin temperature inside the die 105 ℃
Take-off speed 5m / min
The water content of the resin composition pellets composed of EVOH after discharging from the extruder was 20% by weight. The obtained pellets were dried at 100 ° C. for 15 hours using a fluid dryer, and then dried at 100 ° C. for 15 hours using a stationary dryer. As a result, the water content was 0.3% by weight. Moreover, MI was 1.5 g / 10min.
[0105]
Using the resulting dried pellets, EVOH single-layer film formation was carried out, and gel, gel and colorability tests were carried out.
[0106]
As a result of the single-layer film formation under the above conditions, the gel / buzz test and the coloration resistance test were both judged as A.
[0107]
In addition, there is no bridging in the feeder hopper, the raw material resin can be supplied stably to the extruder, and since the pellet surface moisture is low, no water vapor is generated at the bottom of the hopper, and the raw material pellets are fused. Since the supply of the raw material pellets to the extruder is stable, the amount of acid / metal salt added is stable, and the thermal stability is not lowered. Table 1 shows the conditions during extrusion, Table 2 shows the composition of the treatment liquid, and Table 3 shows the evaluation results.
[0108]
[Example 2]
EVOH ethylene content, degree of saponification, resin temperature in the extruder, moisture content before feeding into the extruder and moisture content immediately after the extruder discharge were changed as shown in Table 1, and EVOH was charged per unit time. Except for changing the amount and the charge amount and composition per unit time of at least one solution selected from carboxylic acid, boron compound, phosphate compound, alkali metal salt and alkaline earth metal salt as shown in Table 2, EVOH pellets were prepared in the same manner as in Example 1. Table 1 shows the conditions during extrusion, Table 2 shows the composition of the treatment liquid, and Table 3 shows the evaluation results.
[0109]
In addition, there is no bridging in the feeder hopper, the raw material resin can be supplied stably to the extruder, and since the pellet surface moisture is low, no water vapor is generated at the bottom of the hopper, and the raw material pellets are fused. Since the supply of the raw material pellets to the extruder is stable, the amount of acid / metal salt added is stable, and the thermal stability is not lowered.
[0110]
[Comparative Example 1]
A 45% methanol solution of an ethylene-vinyl acetate copolymer having an ethylene content of 32 mol% was charged into a saponification reactor, and a caustic soda / methanol solution (80 g / L) was added to the vinyl acetate component in the copolymer in an amount of 0. It added so that it might become 4 equivalent, and methanol was added and it adjusted so that a copolymer concentration might be 20%. The temperature was raised to 60 ° C., and the reaction was carried out for about 4 hours while blowing nitrogen gas into the reactor. After 4 hours, the reaction was stopped by neutralizing with acetic acid, and water corresponding to 55% by weight of the total methanol in the reactor was added, and EVOH having an ethylene content of 32 mol% and a saponification degree of 99.5% was added. A solution of methanol and water was obtained. The EVOH solution was extruded from a metal plate having a circular opening into water to precipitate a strand, and was cut to obtain a pellet having a diameter of about 3 mm and a length of about 5 mm. The obtained pellet was drained and the operation of adding a large amount of water and draining was repeated. The obtained pellets had a surface moisture content of 30% by weight and a moisture content of 65% by weight.
[0111]
As a result of the raw material supply continuous test of the obtained pellets, 0.5 hour later, a bridge occurred at the lower part of the hopper, and the operation was stopped. Moreover, although the obtained pellet was formed into a film, gels and blisters were frequently generated, coloring was intense, and the appearance was extremely poor. Table 1 shows the conditions during extrusion, Table 2 shows the composition of the treatment liquid, and Table 3 shows the evaluation results.
[0112]
[Table 1]

[0113]
[Table 2]

[0114]
[Table 3]

As described above, according to the present invention, the following advantages can be obtained.
(1) The occurrence of a bridge in the feeder hopper can be prevented, and the raw material resin can be stably supplied to the extruder.
(2) Since the surface moisture content of the pellet is small, water vapor is not generated in the lower part of the hopper, and the raw material pellet is not fused.
(3) Since the supply of raw material pellets to the extruder is stable, the amount of acid / metal salt added is stable, and the thermal stability is not lowered.
[0115]
【The invention's effect】
As described above, the method for producing an ethylene-vinyl alcohol copolymer (EVOH) resin composition of the present invention is a method in which EVOH resin is melt-kneaded in a water-containing state, and the water content of the whole resin pellet is 0. By supplying the pellets to the extruder in the range of 0.5 to 70% by weight and the moisture content of the surface water of the pellets being less than 10% by weight, the pellets can be efficiently supplied to the extruder.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a schematic process diagram of an embodiment of a method of the present invention.
FIG. 2 is a partially cutaway schematic view of a hopper feeder of one embodiment used in the method of the present invention.
[Explanation of symbols]
1 Raw material supply department
2,4,6 Full flight screw
3,5 Reverse flight screw
7 Vent cylinder
8 Trace component addition part
9 Temperature sensor
10 cylinder barrel
11 Discharge port
20 Twin screw extruder
30 Hopper feeder
31 Hopper
32 lids
33 Level switch
34 Stirrer
35 frame
36 motor
37 screw
38 barrels

Claims (8)

Ethylene - vinyl alcohol copolymer resin was melt-kneaded in a hydrous state ethylene - a method for producing a vinyl alcohol copolymer resin composition,
Supplying the pellets to the extruder with a moisture content of the whole resin pellets in the range of 0.5 to 70% by weight and a moisture content of the surface water of the pellets of less than 10% by weight ;
A method for producing an ethylene-vinyl alcohol copolymer resin composition, wherein the water content of the resin immediately after being discharged from the extruder is 5 to 40% by weight .   The method for producing an ethylene-vinyl alcohol copolymer resin composition according to claim 1, wherein the pellet supply method is a method in which the pellet is quantitatively supplied to an extruder using a quantitative feeder.   The method for producing an ethylene-vinyl alcohol copolymer resin composition according to claim 1 or 2, wherein the additive is melt-kneaded in a water-containing state.   The method for producing an ethylene-vinyl alcohol copolymer resin composition according to any one of claims 1 to 3, wherein the resin melting temperature in the extruder is in the range of 70 to 170 ° C.   The method for producing an ethylene-vinyl alcohol copolymer resin composition according to any one of claims 1 to 4, wherein the ethylene content of the ethylene-vinyl alcohol copolymer is in the range of 3 to 70 mol%.   The method for producing an ethylene-vinyl alcohol copolymer resin composition according to any one of claims 1 to 5, wherein the saponification degree of the ethylene-vinyl alcohol copolymer is in the range of 80 mol% to 100 mol%. Ethylene according to claim 1 water content of the resin immediately after discharge from the extruder to remove the supplied or excess water shortage water in an extruder so that 5 to 40 wt% - vinyl alcohol copolymer resin A method for producing the composition. The extruder according to any one of claims 1 to 7 , wherein at least one additive selected from a carboxylic acid, a boron compound, a phosphoric acid compound, an alkali metal salt and an alkaline earth metal salt is added to the water-containing molten resin in an extruder. A method for producing an ethylene-vinyl alcohol copolymer resin composition.

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