JP2005007835A - Gas-flow conveying method for alicyclic structure-containing thermoplastic resin pellet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas-flow conveying method for the pellet of an alicyclic structure-containing thermoplastic resin which scarcely generates heterogeneous spots such as black spots or unmolten particles in the melt-kneaded moldings of the above resin. <P>SOLUTION: In this gas-flow conveying method for the pellet of an alicyclic structure-containing thermoplastic resin, the mixing weight ratio of the pellet to a conveying gas is regulated to be 2/1 to 4/1. The existence of fine resin particles having a mean particle size of 1-500 μm in the pellet causes in general the occurrence of heterogeneous spots such as black spots or unmolten particles in the moldings obtained by a melt-kneading molding machine. However, if a gas-flow conveyance is performed at the above mixing weight ratio, there is almost no inclusion of the above fine resin particle in the pellet. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００５２】
表１が示すように、ペレット／搬送気体の混合重量比が本発明の規定内にあると、気流搬送による微小樹脂粒子の発生は極めて少なく（実施例１〜３）、２０、３０ｍ／秒の気流速度の相違による影響はほとんどなかった（実施例１，２対比）。
一方、ペレット／搬送気体の混合重量比が本発明の規定より低い１／１であると、気流搬送により微小樹脂粒子が多く発生した（比較例１）。ペレット／搬送気体の混合重量比が本発明の規定より高いと、搬送管に詰りが生じて定常に気流搬送できなかった（比較例２）。
実施例、比較例を通して見ると、微小樹脂粒子の発生量が少ないと成形品に黒点や未溶融粒子の発生が少なく、微小樹脂粒子の発生量が多いと黒点や未溶融粒子の発生が多く見られた。
【００５３】
【発明の効果】
本発明により、脂環式構造含有熱可塑性樹脂の成形品に黒点や未溶融粒子をほとんど発生させないためのペレットの気流搬送方法が提供される。
【図面の簡単な説明】
【図１】図１は本発明方法の一実施形態の、ノルボルネン系熱可塑性樹脂ペレットを乾燥ホッパから押出機に気流搬送する方法を示す概略説明図である。
【図２】図２は実施例の実験設備を示す概略説明図である。
【符号の説明】
１… 乾燥ホッパ
２… ノルボルネン系熱可塑性樹脂ペレット
３、１０… 送風機
４… 除塵フィルタ
５… 冷却機
６… 除湿フィルタ
７… ヒータ
８… スピンダンパ
９… 搬送管
１１… 押出機
１２… 主材料ホッパ
１０１… 乾燥ホッパ
１０２… バルブ
１０３… 送風機
１０４… ダンパ
１０５… 搬送管
１０６… スピンダンパ
１０７、１０９… サイクロン
１０８… 気体配管[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an air current conveying method for an alicyclic structure-containing thermoplastic resin pellet, and more specifically, an air flow of an alicyclic structure-containing thermoplastic resin pellet that does not generate black spots (burnt particles) or unmelted particles during melt-kneading molding. It relates to a transport method.
[0002]
[Prior art]
An alicyclic structure-containing thermoplastic resin typified by a norbornene-based resin is excellent in transparency, low birefringence, heat resistance, low water absorption, etc., so that an optical disk, a super audio disk, a magnetic disk, an optical lens, It is used as a molding material suitable for a liquid crystal display element (LCD), a light guide plate, an optical film, and the like.
In these applications, if the molded product contains foreign substances such as dust, volatile components such as organic components and moisture, as well as black spots and non-homogeneous spots such as unmelted particles due to resin burning and unmelting, the optical characteristics As a result, there is a need for a clean alicyclic structure-containing thermoplastic resin free from foreign matter, organic components, moisture, etc. There is a need to prevent the generation of heterogeneous spots. However, despite the use of a clean alicyclic structure-containing thermoplastic resin and molding with the prevention of foreign matter as much as possible, it is often a black spot with a diameter of 1 to 500 μm or unmelted in an injection molded product or an extruded product. There is a problem that particles are generated to cause damage such as optical properties.
[0003]
[Problems to be solved by the invention]
An object of the present invention is to provide a measure for generating almost no black spots or unmelted particles in a molded article obtained by melt-kneading molding of an alicyclic structure-containing thermoplastic resin.
[0004]
[Means for Solving the Problems]
As a result of diligent research for the above-mentioned purpose, the inventors of the present invention have found that when fine resin particles stay in the molding machine for a long time or float in the molding machine during melt kneading of the alicyclic structure-containing thermoplastic resin, It is considered that unmelted particles are generated, and the fine resin particles are pelletized by impact on the tube wall when the alicyclic structure-containing thermoplastic resin pellets are conveyed by air from the hopper to the molding machine or the like by a duct. As a result, it has been found that the problem is generated by cutting, and the present invention has been completed based on this finding.
Thus, according to the present invention, the following items 1 to 5 are provided.
1. The air current conveyance method of an alicyclic structure containing thermoplastic resin pellet whose mixing weight ratio of an alicyclic structure containing thermoplastic resin pellet and conveyance gas is 2/1-4/1.
2. 2. The air current conveying method of the alicyclic structure-containing thermoplastic resin pellets according to 1 above, wherein the conveying gas has a flow rate of 15 to 30 m / sec.
3. 3. The airflow conveying method of the alicyclic structure-containing thermoplastic resin pellet according to the above 1 or 2, wherein the temperature of the alicyclic structure-containing thermoplastic resin pellet is (Tg-50) to (Tg-5) ° C.
[Here, Tg represents the glass transition temperature (unit: ° C.) of the alicyclic structure-containing thermoplastic resin. ]
4). An optical disk formed by injection molding of an alicyclic structure-containing thermoplastic resin pellet conveyed to a molding machine by the air current conveying method according to any one of 1 to 3 above.
5. An optical film formed by extruding an alicyclic structure-containing thermoplastic resin pellet conveyed to a molding machine by the air current conveying method according to any one of 1 to 3 above.
[0005]
[Action]
Conventionally, pellet air flow is usually performed by setting the mixing weight ratio of the pellet and the carrier gas to 1/100 to 1/20 (for example, in Japanese Patent No. 3066504, air is 0 per gram of pellet even at a high concentration. .1m³As about 1% by weight. ).
In the present invention, alicyclic structure-containing thermoplastic resin pellets are air-flowed from a hopper (pellet silo, dry hopper, etc.) to an injection molding machine, a melt-kneading molding machine such as an extruder, etc. by an air-flow conveying pipe (duct, pipe, etc.). In doing so, the mixing weight ratio of the pellets to the carrier gas is set to a range of 2/1 to 4/1. As a result, generation of fine resin particles having a diameter of 1 to 500 μm can be suppressed. This is thought to be due to the fact that by adopting the above-mentioned mixing weight ratio, the pellets play a role of cushioning each other, reducing the impact on the tube wall and preventing the occurrence of scraping and cracking.
By molding the alicyclic structure-containing thermoplastic resin pellet containing almost no fine resin particles by melt-kneading molding such as injection molding or extrusion molding, a molded product with extremely few black spots and unmelted resin particles can be obtained.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The airflow conveyance method of the alicyclic structure-containing thermoplastic resin pellets of the present invention is characterized in that the mixing weight ratio of the pellets and the conveyance gas is 2/1 to 4/1.
[0007]
The alicyclic structure-containing thermoplastic resin used in the present invention is a polymer containing 50% by weight or more of repeating units having an alicyclic structure in the polymer, and the glass transition temperature (Tg) is usually It refers to a resin having a temperature of 50 to 300 ° C, preferably 60 to 200 ° C, more preferably 70 to 170 ° C. Here, Tg is measured with a differential scanning calorimeter at a heating rate of 10 ° C./min.
In the present invention, when the alicyclic structure-containing thermoplastic resin has an unsaturated bond, it is preferable to hydrogenate the resin.
The number of carbon atoms constituting the ring is usually in the range of 4 to 30, preferably 5 to 20, and more preferably 5 to 15 from the viewpoint of mechanical strength, heat resistance, and moldability of the molded product. .
[0008]
The molecular weight of the alicyclic structure-containing thermoplastic resin is appropriately selected according to the purpose of use, but measured by gel permeation chromatography using a cyclohexane solution (or a toluene solution if the polymer resin does not dissolve). The weight average molecular weight in terms of polyisoprene is usually in the range of 5,000 to 500,000, preferably 8,000 to 200,000, more preferably 10,000 to 100,000. A molecular weight within the above range is preferable because the mechanical strength and molding processability of the molded product are balanced.
[0009]
Specific examples of such alicyclic structure-containing thermoplastic resins include norbornene polymers, monocyclic cycloalkene polymers, vinyl alicyclic hydrocarbon polymers, aromatic vinyl polymers, and cyclic conjugated diene polymers. Etc. Examples of the alicyclic structure include monocycles and polycycles (condensed polycycles, bridged rings, combination polycycles thereof, and the like). The number of carbon atoms constituting the alicyclic structure is usually in the range of 4 to 30, preferably 5 to 20, and more preferably 5 to 15. When the carbon number of the alicyclic structure is in the above range, various properties such as mechanical strength, heat resistance and moldability are highly balanced, which is preferable.
[0010]
The norbornene-based polymer is obtained by hydrogenating a ring-opening (co) polymer of a norbornene-based monomer, an addition (co) polymer of a norbornene-based monomer, and if necessary, an unsaturated bond portion thereof. A polymer etc. are mentioned.
A monocyclic cycloalkene polymer can be obtained by addition (co) polymerization of a monocyclic cycloalkene monomer or a cyclic conjugated diene monomer and hydrogenating an unsaturated bond portion.
Vinyl cycloaliphatic hydrocarbon polymer is a polymer of vinyl cycloalkane; (co) polymerization of vinyl cycloalkene polymer or vinyl cycloalkane or other monomer copolymerizable with vinyl cycloalkene Depending on the case, polymers obtained by hydrogenating those unsaturated bond portions may be mentioned.
Aromatic vinyl polymers (co) polymerize aromatic vinyl compounds or other monomers copolymerizable with aromatic vinyl compounds and hydrogenate aromatic rings and olefinically unsaturated bonds as necessary. To obtain.
The cyclic conjugated diene polymer is an addition (co) polymer of a cyclic conjugated diene monomer.
Among these, a ring-opening (co) polymer of a norbornene monomer and a hydride thereof are preferable.
[0011]
In the present invention, the norbornene-based monomer, monocyclic cycloalkene, cyclic conjugated diene and vinyl alicyclic hydrocarbon may be referred to as “alicyclic structure-containing monomer”.
[0012]
Examples of the alicyclic structure-containing monomer include bicyclo [2.2.1] hept-2-ene (common name: norbornene) and its derivatives, tricyclo [4.3.0. 1^2,5Deca-3,7-diene (common name: dicyclopentadiene), tricyclo [4.3.0.1]^2,5] Dec-3-ene, tricyclo [4.4.0.1]^2,5] Undeca-3,7-diene, tricyclo [4.4.0.1]^2,5] Undeca-3,8-diene, tricyclo [4.4.0.1]^2,5] Undec-3-ene, tetracyclo [7.4.0.1]^{10, 13}. 0^2,7] Trideca-2,4,6,11-tetraene (also known as 1,4-methano-1,4,4a, 9a-tetrahydrofluorene), 1,4-methano-1,4,4a, 5,10,10a -Hexahydroanthracene, 6-methyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, tetracyclo [4.4.0.1^2,5. 1^{7, 10}] Dodec-3-ene (common name: tetracyclododecene) and its derivatives;
[0013]
Cyclobutene, cyclopentene, cyclohexene, 3,4-dimethylcyclopentene, etc. as monocyclic cycloalkenes; cyclopentadiene, cyclohexadiene, etc. as cyclic conjugated diene monomers; vinylcyclopentane, 2-methyl-4- as vinyl alicyclic hydrocarbons And vinylcycloalkanes such as vinylcyclopentane, vinylcyclohexane and vinylcyclooctane, and vinylcycloalkenes such as vinylcyclopentene, 2-methyl-4-vinylcyclopentene and vinylcyclohexene.
[0014]
On the other hand, examples of the aromatic vinyl compound include styrene, α-methylstyrene, divinylbenzene, vinyl naphthalene, and vinyl toluene.
The above alicyclic structure-containing monomers and aromatic vinyl compounds can be used alone or in combination of two or more.
[0015]
Examples of the alicyclic structure-containing monomer or other monomer copolymerizable with the aromatic vinyl compound include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, Chain olefins such as 3-methyl-1-pentene; non-conjugated dienes such as 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 1,7-octadiene, etc. Is mentioned. These monomers can be used alone or in combination of two or more.
[0016]
The alicyclic structure-containing thermoplastic resin contains polar groups such as hydroxyl group, carboxyl group, alkoxyl group, epoxy group, glycidyl group, oxycarbonyl group, carbonyl group, amide group, ester group, and acid anhydride group. It may be.
[0017]
The polymerization method of the alicyclic structure-containing thermoplastic resin and the hydrogenation method performed as necessary are not particularly limited and can be performed according to a known method.
[0018]
The ring-opening polymerization of the norbornene monomer and the monocyclic cycloalkene is a catalyst comprising a metal halide such as ruthenium, palladium, osmium, platinum, nitrate or acetylacetone compound and a reducing agent as a ring-opening polymerization catalyst, Alternatively, a catalyst comprising a metal halide such as titanium, vanadium, zirconium, tungsten, molybdenum or an acetylacetone compound and a co-catalyst organoaluminum compound is used, and the temperature is usually −50 ° C. to 100 ° C. and the pressure is 0 Perform at ~ 5 MPa.
Addition copolymerization of norbornene-based monomers and monocyclic cycloalkenes or the above-mentioned copolymerizable monomers includes, for example, a monomer component, a titanium, zirconium, or vanadium compound and an organic promoter. In the presence of a catalyst comprising an aluminum compound, the reaction is usually carried out at a temperature of −50 ° C. to 100 ° C. and a pressure of 0 to 5 MPa.
[0019]
The polymerization reaction of the aromatic vinyl compound, vinylcycloalkane or vinylcycloalkene may be any of known methods such as radical polymerization, anionic polymerization, and cationic polymerization. In cationic polymerization, the molecular weight of the polymer is reduced. Anionic polymerization is preferred because the molecular weight distribution tends to widen and the mechanical strength of the molded product tends to decrease. Moreover, any of suspension polymerization, solution polymerization, and bulk polymerization may be used. Among these polymers, aromatic vinyl compound homopolymers and hydrides of random and block copolymers containing 50% by weight or more of aromatic vinyl compound units are preferred. The styrene homopolymer hydride may be any of isotactic, syndiotactic and atactic.
[0020]
Anionic polymerization of an aromatic vinyl compound, vinylcycloalkane or vinylcycloalkene specifically uses an organic alkali metal such as n-butyllithium or 1,4-dilithiobutane as a polymerization catalyst in an organic solvent. For the purpose of ensuring mechanical strength and heat resistance, a Lewis base such as dibutyl ether or triethylamine is added to obtain a polymer having a narrow molecular weight distribution.
The organic solvent is preferably a hydrocarbon solvent, for example, an aliphatic hydrocarbon such as n-pentane, n-hexane or isooctane; an alicyclic hydrocarbon such as cyclopentane or cyclohexane; an aromatic hydrocarbon such as benzene or toluene. An ether such as tetrahydrofuran and dioxane; The amount of the organic solvent used is such that the monomer concentration is usually 1 to 40% by weight, preferably 10 to 30% by weight.
The anionic polymerization reaction is usually −70 to 150 ° C., preferably −50 to 120 ° C., and usually 0.01 to 20 hours, preferably 0.1 to 10 hours.
[0021]
Polymerization of the cyclic conjugated diene monomer can be performed by a known method described in, for example, JP-A Nos. 6-136057 and 7-258318.
[0022]
The polymerization conversion rate of the alicyclic structure-containing thermoplastic resin is usually 95% by weight or more, preferably 97% by weight or more, more preferably 99% by weight or more. By increasing the polymerization conversion rate, it is possible to obtain a molded product having a smaller amount of released organic matter.
[0023]
When the above-described alicyclic structure-containing thermoplastic resin is hydrogenated after the polymerization reaction, the ring, main chain, and side chain carbon-carbon unsaturated bonds can be reduced in the amount of released organic matter. The ratio of the number of carbon-carbon double bonds to the total number of carbon-carbon bonds in the alicyclic structure-containing thermoplastic resin by hydrogenation is usually 0.15% or less, preferably 0.07% or less, more preferably 0.02% or less. As the double bond ratio is reduced, a molded product with a reduced amount of released organic matter can be obtained.
[0024]
In the hydrogenation reaction, the reaction temperature, the hydrogen partial pressure, the reaction time, and the reaction solution concentration are appropriately set within the optimum ranges depending on the type of polymer to be hydrogenated. In the hydrogenation reaction, usually, the reaction time is 25 to 300 ° C. with a hydrogen partial pressure of 0.5 to 10 MPa using 0.01 to 50 parts by weight of a hydrogenation catalyst per 100 parts by weight of the polymer to be hydrogenated. The reaction is performed for 0.5 to 20 hours.
As the hydrogenation catalyst, for example, a homogeneous catalyst formed by combining a metal compound such as nickel or cobalt with organic aluminum or organic lithium is preferable. A carrier such as activated carbon, diatomaceous earth, or magnesia is used as necessary. The amount of the hydrogenation catalyst used is usually such that the catalyst component is 0.03 to 50 parts by weight per 100 parts by weight of the polymer to be hydrogenated.
[0025]
The hydrogenated alicyclic structure-containing thermoplastic resin is recovered by filtering the hydrogenation reaction solution to remove volatile components such as a solvent from the solution obtained by filtering the hydrogenation catalyst. In order to speed up filtration, filter aids such as diatomaceous earth, silica, synthetic zeolite and perlite are added to the solution (body feed), or a filter bed is previously formed in the filter with filter aid. Filtration may be performed from (precoat).
Examples of the method for removing the volatile component include a coagulation method and a direct drying method. By using the direct drying method, a molded product having a smaller amount of released organic substances can be obtained.
[0026]
The coagulation method is a method for precipitating a polymer by mixing a polymer solution with a poor solvent for the polymer. Examples of the poor solvent include alcohols such as ethyl alcohol, n-propyl alcohol, and isopropyl alcohol; Examples include polar solvents such as ketones such as acetone and methyl ethyl ketone; esters such as ethyl acetate and butyl acetate. After solidification and solid-liquid separation, the small polymer (crumb) is dried by heating to remove the solvent.
The direct drying method is a method in which the polymer solution is heated under reduced pressure to remove the solvent. This method can be carried out using a known apparatus such as a centrifugal thin film continuous evaporation dryer, a chamfered heat exchange type continuous reactor type dryer, a high viscosity reactor device, or a cylindrical concentration dryer. The degree of vacuum and temperature can be appropriately selected depending on the apparatus.
The alicyclic structure-containing thermoplastic resin is dried by heating under reduced pressure after removing the solvent by a coagulation method or a direct drying method. As a result, a resin material can be obtained that gives a molded product with a smaller amount of released water and less released organic matter. The pressure during drying is usually 10 kPa or less, preferably 3 kPa or less, and the heating temperature is usually 260 ° C. or more, preferably 280 ° C. or more.
[0027]
In the present invention, the alicyclic structure-containing thermoplastic resin is used as a pellet. In the present invention, the pellet is a resin material for molding, and after melting and kneading a thermoplastic resin alone or a mixture in which a compounding agent is blended with the thermoplastic resin as necessary, an average representative length, Usually, the size is 0.5 to 20 mm, preferably 1 to 10 mm. Here, the representative length means the length of the maximum portion when projected. For example, the average representative length in a cylindrical pellet having an average diameter of 2 mm and an average length of 3 mm obtained by using a pelletizer from a strand extruded by an extruder is a square root of the sum of 2 squares and 3 squares. 3.6 mm. The average representative length of a flat spherical pellet having an average diameter of 10 mm and an average maximum thickness of 5 mm at the center obtained by extrusion with a twin screw kneader having a flat sphere pelletizer at the tip is 11.2 mm.
[0028]
The compounding agents blended as necessary include antioxidants, ultraviolet absorbers, weathering stabilizers, antistatic agents, stabilizers, near infrared absorbers, colorants such as dyes and pigments, and other thermoplastic resins. , Rubbery polymers, lubricants, plasticizers, antiblocking agents, optical brighteners, deodorizers, organic or inorganic fillers, crosslinking agents, vulcanizing agents and the like.
Antioxidants can prevent coloring of molded products and mechanical strength reduction due to oxidative degradation during molding without reducing transparency, low water absorption, etc. of thermoplastic resin containing alicyclic structure. Of particular importance.
[0029]
The air current conveying method of the alicyclic structure-containing thermoplastic resin pellets of the present invention includes pellet transfer from a pellet silo in a pellet maker to a tank lorry filling for shipping, a pellet drying hopper in a resin molding maker, an injection molding machine, an extruder, The present invention can be applied to pellet supply to a melt kneading molding machine such as a blow molding machine or a vacuum molding machine.
[0030]
The shape of the carry-out tank such as a pellet silo or a dry hopper is not limited, but is usually a hollow cylindrical shape or a rectangular tube shape having a diameter of 20 to 500 cm, or a width and depth of 20 to 500 cm, and a height of 30 to 500 cm. A structure having a cone portion at the bottom is preferable.
When producing optical discs, super audio discs, optical films, etc., it is preferable that almost no organic components or moisture is detected in the alicyclic structure-containing thermoplastic resin pellets. It is preferable that the material is retained for a predetermined time before being used for molding. In the drying hopper, dry gas is vented from a nozzle inserted from the outside so as to reach the center of the lower cone portion, and volatile components are removed from the stored pellets.
[0031]
A switch that does not apply mechanical shearing force to the pellet, such as a spin damper or an air valve, is installed at the discharge port at the lower end of the carry-out tank, and the pellet passes through the switch and flows into the transport pipe.
[0032]
In the method of the present invention, the alicyclic structure-containing thermoplastic resin pellets are carried on a carrier gas through a carrier pipe from a carry-out tank to a destination such as a molding machine or a tank truck.
The inner diameter of the conveying tube is usually 25 to 120 mm, preferably 40 to 90 mm. Although there is no limitation in the length of a conveyance pipe | tube, since a pressure loss will become large when it exceeds 50 m, it is not preferable.
The material of the unloading tank and the transfer pipe is preferably austenitic stainless steel, ferritic stainless steel, chromium-molybdenum steel, nickel-chromium steel, alloy steel with titanium, aluminum, or the like, and more preferably austenitic stainless steel. It is not preferable to use a flexible tube for the curved portion because the inner surface is not smooth and the pellets collide and there is a risk that a large amount of shavings may be generated due to friction.
[0033]
As the carrier gas, a gas inert to the resin such as air or nitrogen is used. The carrier gas is preferably dedusted and dehumidified. For example, air removed from a cyclone or a filter is passed through a cooling device to condense moisture, then passed through a filter to remove the condensed water, and further heating, cooling and dehumidification are repeated 1 to 3 times before use.
[0034]
In the method of the present invention, the mixing weight ratio of the pellet and the transport gas in the transport pipe is 2/1 to 4/1, preferably 2/1 to 3.5 / 1, more preferably 2/1 to 3/1. is there. As described above, the mixing weight ratio in the above range is a much larger value than the conventional air current conveyance of pellets, but in this range, the generation of fine resin particles having a diameter of 1 to 500 μm is small during the air current conveyance. It is considered that the pellet concentration is high because the pellet concentration is high, and the frequency of collision with the tube wall is reduced to suppress the occurrence of scraping or cracking. If the mixing ratio is too small, the generation of fine resin particles increases, and black spots and unmelted particles may occur frequently in the molded product. Conversely, if the mixing ratio is too large, the pressure loss increases and airflow conveyance becomes difficult. There is a possibility.
[0035]
The flow rate of the carrier gas is usually 15 to 30 m / second, preferably 18 to 25 m / second. If the flow velocity of the carrier gas is too small, it may be difficult to convey, and conversely if the flow velocity is too large, the collision energy to the tube wall will increase, and the generation of fine resin particles due to pellet scraping and cracking will increase. there is a possibility.
[0036]
As the glass transition temperature Tg (° C.) of the resin, the temperature of the alicyclic structure-containing thermoplastic resin pellet is usually (Tg-50) to (Tg-5) ° C., preferably (Tg-50). To (Tg-10) ° C. If the temperature of the pellet is too low, there is a risk of problems such as silver streaks occurring in the molded product. Conversely, if the temperature of the pellet is too high, the pellet may be heat-sealed, or the molded product may be abnormal in color tone. There is sex.
[0037]
The alicyclic structure-containing thermoplastic resin pellets transported to a destination such as a molding machine hopper or tank truck by airflow transport are trapped by a collecting means such as a cyclone or a bag filter and stored in a receiving container.
The alicyclic structure-containing thermoplastic resin pellets that have been air-flowed by the method of the present invention and contained in a receiving container are prevented from being scraped and cracked during air-flow transportation, and are almost mixed with fine resin particles having a diameter of 1 to 500 μm. Not.
[0038]
If the alicyclic structure-containing thermoplastic resin pellet contains a large amount of fine resin particles, the pellet is molded into a molded product by a melt-kneading molding machine (injection molding machine, extrusion molding machine, blow molding machine, vacuum molding, etc.). In addition, many black spots and unmelted particles having a diameter of about 1 to 500 μm are observed. On the contrary, when the alicyclic structure-containing thermoplastic resin pellet containing almost no fine resin particles is molded by a melt kneading molding machine, almost no black spots or unmelted particles are seen in the molded product.
[0039]
The causal relationship between the number of fine resin particles and the number of black spots in the molded product and the number of unmelted particles is not fully understood, but when the resin pellets melt, the fine resin particles cannot float into the molten flow and float. Is considered to lead to the generation of sunspots and unmelted particles.
For example, when a lot of fine resin particles are interposed between cylindrical alicyclic structure-containing thermoplastic resin pellets having an average diameter of 3 mm and an average length of 3 mm, the pellets are melted and kneaded in a cylinder of an injection molding machine. The lump of unit is kneaded by flight by screw rotation, forming a melt flow, and going up and down the flight mountain and valley and sent to the die. On the other hand, since the fine resin particles are not caught in the flight, the fine resin particles do not immerse in the melt flow, and float on the melt flow. When the suspended fine resin particles touch the heated barrel, it adheres and stays there, discolors black due to thermal decomposition by heating for a long time, is rubbed off by a large melt flow and mixed into the molded product, It is thought to be observed as a sunspot. On the other hand, if the fine resin particles float on the molten flow and proceed to the die without touching the barrel, it is considered that they become unmelted particles and are observed in the molded product.
[0040]
An optical disk, super audio disk, etc. obtained by injection molding of an alicyclic structure-containing thermoplastic resin pellet that is hardly mixed with fine resin particles conveyed by the method of the present invention, an optical film obtained by extrusion molding, etc. Has almost no black spots or unmelted particles. Therefore, the molded product is excellent in optical characteristics, electrical characteristics, surface characteristics, and the like.
Examples of applications of the alicyclic structure-containing thermoplastic resin pellets conveyed by airflow according to the method of the present invention include the following molded products. Optical disc; super audio disc; optical fiber, camera lens, overhead projector lens, FBP lens for LBP, prism, liquid crystal display element (LCD), light diffusion plate, light guide plate, polarizing film, retardation film, brightness enhancement film, collection Optical products such as optical films; various clean containers such as liquid chemical containers, ampoules, infusion bags, eye drop containers, semiconductor wafer storage containers; medical equipment such as syringes and medical infusion tubes.
[0041]
Hereinafter, the present invention will be described based on embodiments shown in the drawings.
FIG. 1 is a schematic explanatory view showing a method for air-conveying norbornene-based thermoplastic resin pellets stored in a dry hopper to an extruder, which is an embodiment of the method of the present invention. The device in contact with the pellet and the equipment through which the carrier gas passes are made of austenitic stainless steel except for the filter.
[0042]
Norbornene polymer pellets (average diameter 3 mm, average length 3 mm, cylindrical shape; resin Tg 140 ° C.) 2 stored in the dry hopper 1 were taken in by the blower 3. The organic components and moisture contained in the air are slightly contained by receiving the circulation of the dry air produced by the air being dedusted by the dust filter 4, cooled by the cooler 5, then dehumidified by the dehumidifier filter 6 and then heated by the heater 7. Release. Next, the norbornene-based polymer pellets passed through the spin damper 8 and supplied to the transport pipe 9 ride on the transport air from the blower 10 from which dust and moisture have been removed through a dust removal and dehumidification process (not shown). It is accommodated in the main material hopper 12 located in the immediate vicinity of the inlet of the extruder 11 through the transport pipe 9. The mixing weight ratio of the norbornene polymer pellets and the carrier gas in the carrier tube 9 is 2/1 to 4/1. Moreover, the flow rate of this conveyance machine body is 15-30 m / sec, and the temperature of a pellet is 90-135 degreeC.
In the norbornene-based thermoplastic resin pellet in the main material hopper 12, almost no fine resin particles having a diameter of 1 to 500 μm are observed.
[0043]
【Example】
Hereinafter, the present invention will be described more specifically with reference to reference examples, examples and comparative examples. However, the present invention is not limited to these examples. In the following, “part” or “%” is based on weight unless otherwise specified.
[0044]
The measuring methods of various physical properties in the following examples and comparative examples are as follows.
(1) Hydrogenation rate (hydrogenation rate)
The hydrogen conversion rate to the unsaturated bond of the alicyclic structure-containing thermoplastic resin is¹Measured by 1 H-NMR. unit%.
(2) Glass transition temperature (Tg)
The Tg of the alicyclic structure-containing thermoplastic resin was measured with a differential scanning calorimeter at a rate of temperature increase of 10 ° C./min based on JIS K7121. Unit ° C.
(3) Weight average molecular weight (Mw) and number average molecular weight (Mn) of thermoplastic resin containing alicyclic structure
It measured by the polyisoprene conversion value by GPC which uses a cyclohexane as a solvent.
[0045]
(4) Amount of fine resin particles
The weight of fine resin particles having a diameter of 1 to 500 μm in the cycloaliphatic structure-containing thermoplastic resin pellets collected by the cyclone was measured, and the weight ratio with respect to the pellets before the air current conveyance experiment was obtained. Unit ppm.
[0046]
(5) Black spots and unmelted particles (proportion of inhomogeneous spots)
A resin material was prepared by blending 100 parts of resin pellets with fine resin particles having a diameter of 1 to 500 μm collected by a cyclone so as to match the generation ratio. In a clean booth installed in a clean room with a clean degree of class 1000, an injection molding machine (SD40ER, manufactured by Sumitomo Heavy Industries, Ltd.) in which the die part is maintained in an environment of clean degree class 100 has a high SACD recording density layer. A stamper was installed on the fixed side. The resin material is charged into this injection molding machine, the resin temperature (maximum barrel setting temperature) is 375 ° C., and the mold temperature is 103 ° C. on the fixed side and 105 ° C. on the movable side to reduce warpage. A disk single plate (base) having a recorded layer and a diameter of 120 mm and a thickness of 0.6 mm was formed. The compression force of the mold has a capacity of 4.5 MPa at the maximum, the initial mold opening amount is set to 0.6 mm by the mold opening amount control, and the maximum is 0.07 seconds after the start of injection. The mold was closed by compressive force. The cooling time (time from the completion of injection filling to the start of mold opening) was 2.5 seconds. The pellets are heat-treated at 100 ° C for 4 hours in a dryer until molding, and are molded within 30 minutes after taking out the dryer. At the bottom of the molding machine hopper, nitrogen as an inert gas is about 5 liters / minute. The nitrogen substitution was carried out at a feed rate of
100 substrates were extracted for inspection after continuous molding for 1 hour, and the number of substrates on which black spots or unmelted particles with a particle size of 1 μm or more were observed was counted with an appearance inspection device (S3 Blank scanner, manufactured by BASLER), and the ratio Asked.
[0047]
Reference example 1(Manufacture of alicyclic structure-containing thermoplastic resin)
6-methyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene (hereinafter referred to as MTD) 90% and 5-methyl-2- A hydrogenation catalyst was prepared by dissolving 100 parts of a ring-opening copolymer obtained by polymerizing a monomer containing 10% norbornene (hereinafter referred to as MNB) using a ring-opening polymerization catalyst in 400 parts of cyclohexane. 5 parts of a nickel-alumina catalyst (manufactured by JGC Chemical Co., Ltd.) was added, pressurized to 5 MPa with hydrogen, heated to 200 ° C. with stirring, reacted for 4 hours, and MTD-MNB ring-opening copolymer hydrogen. Compound (norbornene polymer) was obtained. The reaction solution after hydrogenation was diluted with cyclohexane so that the hydride content of MTD-MNB ring-opening copolymer was 20%, and diatomaceous earth (Radiolite # 500) was used as a filtration bed, and pressure filtration (Hunda filter, The product was filtered under pressure at a pressure of 0.25 MPa to obtain a colorless and transparent MTD-MNB ring-opening copolymer hydride solution I.
[0048]
100 parts of MTD-MNB ring-opening copolymer hydride solution I was further filtered with a metal fiber filter (caliber 3 μm, manufactured by Nichidai), and then zeta plus filter 10H (caliber 0.5-1 μm, manufactured by Cuno). ), And further filtered with a metal fiber filter (caliber 0.2 μm, manufactured by Nichidai Co., Ltd.) to remove foreign substances. In the obtained filtrate, antioxidants (Irganox 1010, Ciba Specialty Chemicals) and a rubbery polymer (Tuftec H1052, manufactured by Asahi Kasei Co., Ltd.) were added to the solution so as to be 0.2 parts relative to 100 parts of the MTD-MNB ring-opening copolymer hydride. Added. Then, cyclohexane was removed as a first step (temperature 270 ° C., pressure 13.3 kPa) and a second step (temperature 270 ° C., pressure 667 Pa) using a cylindrical concentrating dryer (manufactured by Hitachi, Ltd.). . The obtained resin composition was extruded from a die in a molten state through an extruder in a class 1000 clean room, cooled with water, passed through a pelletizer (OSP-2, manufactured by Nagata Seisakusho) to form a 3 mm diameter strand, and a strand cutter. It cut | disconnected by 3 mm length and obtained 18 parts of MTD-MNB ring-opening copolymer hydride pellets. The pellets were stored in a sealed stainless steel container whose surface was polished. As a result of analyzing a 10% by weight pellet solution in toluene by gas chromatography, the amount of residual cyclohexane was below the measurement limit. The MTD-MNB ring-opening copolymer hydride was colorless and transparent, Mw 42000, Mn 18000, Tg 140 ° C., and the hydrogenation rate was almost 100%.
[0049]
Example 1
Airflow conveyance experiment equipment shown in Fig. 2 for the MTD-MNB ring-opening copolymer hydride pellets 4.5 kg prepared in Reference Example 1 (all the austenitic stainless steel except for the equipment that touches the pellet and the equipment through which the carrier gas passes are filters) In a dry hopper (KAWATA CLB30Z, manufactured by Kawata) 101, the temperature of the pellet packed bed is 110 ° C., the valve 102 is opened, the blower 103 is operated, the opening degree of the damper 104 is adjusted, and the conveying pipe 105 The flow rate at an inner diameter of 35 mm and a length of 10 m was 20 m / sec. Subsequently, while adjusting the opening degree of the spin damper 106, the resin pellets in the drying hopper 1 were guided to the transport pipe 105, and the pellet / carrier gas mixing weight ratio in the transport pipe 105 was set to 3/1. The pellets in the transport pipe 105 were collected by the cyclone 107 and returned to the drying hopper 101, and the transport gas was exhausted through the gas pipe 108 (inner diameter 35 mm, length 5 m) by dropping fine resin particles in the cyclone 109. The blower 103 was stopped after 120 minutes when the pellets made 10 rounds. The fine resin particles collected by the cyclone 109 passed through a 42-mesh (aperture 350 μm) sieve. Table 1 shows the results of examining the amount of fine resin particles and the ratio of occurrence of inhomogeneous spots in the molded product.
[0050]
Examples 2-3 and Comparative Examples 1-2
Example 1 was carried out in the same manner as Example 1 except that the flow rate and the pellet / carrier gas mixing weight ratio were the conditions shown in Table 1. Table 1 shows the results of examining the amount of fine resin particles collected by the cyclone 109 and the ratio of occurrence of inhomogeneous spots in the molded product.
[0051]
[Table 1]

[0052]
As Table 1 shows, when the pellet / carrier gas mixing weight ratio is within the limits of the present invention, the generation of fine resin particles due to air current conveyance is extremely small (Examples 1 to 3), and 20 and 30 m / second. There was almost no influence by the difference in the air velocity (Comparison with Examples 1 and 2).
On the other hand, when the mixing weight ratio of the pellet / conveying gas was 1/1 lower than that of the present invention, a large amount of fine resin particles were generated by the air current conveyance (Comparative Example 1). When the mixing weight ratio of the pellet / carrier gas was higher than that of the present invention, the carrier tube was clogged, and the air current could not be constantly conveyed (Comparative Example 2).
Looking through the examples and comparative examples, if the amount of fine resin particles generated is small, the molded product has few black spots and unmelted particles. If the amount of fine resin particles generated is large, many black spots and unmelted particles are generated. It was.
[0053]
【The invention's effect】
According to the present invention, there is provided a method for conveying pellets in an air stream so as to hardly generate black spots or unmelted particles in a molded product of an alicyclic structure-containing thermoplastic resin.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory view showing a method for conveying a norbornene-based thermoplastic resin pellet from a drying hopper to an extruder in an air flow according to an embodiment of the method of the present invention.
FIG. 2 is a schematic explanatory view showing an experimental facility of the example.
[Explanation of symbols]
1 ... Drying hopper
2 ... Norbornene thermoplastic pellets
3, 10 ... Blower
4 ... Dust filter
5 ... Cooling machine
6 ... Dehumidification filter
7 ... Heater
8 ... Spin damper
9 ... Transport pipe
11 ... Extruder
12 ... Main material hopper
101 ... Drying hopper
102 ... Valve
103 ... Blower
104 ... Damper
105 ... Conveying pipe
106 ... Spin damper
107, 109 ... Cyclone
108 ... Gas piping

Claims (5)

The air current conveyance method of an alicyclic structure containing thermoplastic resin pellet whose mixing weight ratio of an alicyclic structure containing thermoplastic resin pellet and conveyance gas is 2/1-4/1. The airflow conveying method of the alicyclic structure-containing thermoplastic resin pellets according to claim 1, wherein a flow velocity of the conveying gas is 15 to 30 m / sec. The method of air current conveyance of an alicyclic structure content thermoplastic resin pellet according to claim 1 or 2 whose temperature of said alicyclic structure content thermoplastic resin pellet is (Tg-50)-(Tg-5) ° C.
[Here, Tg represents the glass transition temperature (unit: ° C.) of the alicyclic structure-containing thermoplastic resin. ] An optical disk formed by injection molding an alicyclic structure-containing thermoplastic resin pellet conveyed to a molding machine by the air current conveying method according to claim 1. The optical film formed by extrusion molding the alicyclic structure containing thermoplastic resin pellet conveyed to the molding machine by the airflow conveyance method in any one of Claims 1-3.

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