JPH07314524A - Extrusion molding machine - Google Patents

Abstract

PURPOSE:To obtain a extrusion molding machine for extruding a crosslinked resin composition composed of a thermoplastic resin and a crosslinking agent into a long land die in order to cause crosslinkage wherein back pressure can be applied to a molten resin in the long land die using a deformed die and the extrusion can be continued stably for a long time. CONSTITUTION:In the extrusion molding machine, a shaping die 2 is coupled with the outlet of an extruder 1 and a long land die 3 is coupled with the outlet of the shaping die 2. A lubricant feeding part 6 is disposed between the shaping die and the long land die and a deformed die having a cross-section extending perpendicularly to the advancing direction of resin in a resin channel of the long land die 3 and another cross-section of same area and different shape is provided at the outlet of the long land die 3.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an extrusion molding apparatus. More specifically, the present invention relates to an extrusion molding apparatus for a cross-linked extrusion molded article, which is used as an electric material, a water / hot water supply material, a building material, a packaging material, and the like.

[0002]

2. Description of the Related Art Conventionally, as a method for continuously extruding a crosslinkable resin material to obtain an extruded product, for example, JP-A-48-
As described in Japanese Patent No. 96656, when an extruded product is obtained by extruding a crosslinkable resin material from a long land die having a certain temperature and a certain length, in the vicinity of the base of the long land die, the inner wall of the long land die and the passage therethrough are passed. A method has been proposed in which a sufficient amount of lubricant is supplied to the interface between the resin material and the molded product, and the lubricant is sucked and removed in the vicinity of the tip of the long land die. In this method, the temperature and length of the long land die are set so that the cross-linking reaction of the cross-linking resin material passing therethrough is completed, and cross-linked molded articles are continuously obtained from the long land die outlet.

In this method, since a long land die is present in the molding process, a high back pressure is applied to the plasticizing zone of the crosslinkable resin material, so that it passes through the inner wall of the long land die. A method of supplying a lubricant to the interface with the crosslinkable resin material or the molded article to reduce the frictional resistance between the inner wall of the long land die and the crosslinkable resin material or the molded article has been adopted. However, this molding method has a drawback that voids are generated in the molded product because the crosslinking agent decomposes or the additive thermally decomposes to generate gas.

As a method of suppressing the gas generated in the step of forming a crosslink by applying a pressure to the molten resin, for example, Japanese Patent Laid-Open No. 62-212122 discloses a crosslinkable thermoplastic resin, a foaming agent and a resin. Mixing with a cross-linking agent having a thermal decomposition temperature higher than the melting temperature of, in obtaining a cross-linked foam extruded from a long land die of a certain temperature and a certain length, the die and the molten resin from the vicinity of the entrance of the long land die In addition to supplying a sufficient amount of lubricant to the sliding contact part of, the drawing die is provided between the front and rear stages of the long land die to apply back pressure to the molten resin in the long land die at the previous stage. Further, there has been proposed a method of controlling the back pressure of the molten resin by adjusting the removal amount of the lubricant present in the sliding contact portion between the die and the molten resin according to the level of the back pressure of the molten resin. .

In this method, a drawing die is provided between the front and rear stages of the long land die to apply pressure to the molten resin in the long land die at the front stage so that a part of the foaming agent volatilizes or A method of preventing decomposition and removing the lubricant accumulated in front of the drawing die according to the level of back pressure is adopted.

[0006]

However, in this molding method, since the response of the resin back pressure change to the amount of lubricant removed is slow, it is difficult to obtain the stability of the back pressure by controlling the amount of lubricant removed. , For example, even if the amount of lubricant removed is reduced after the back pressure starts to rise, at least the time required for the resin to replace the drawing die is necessary to return to the original lubrication state.
In the worst case, the lubricant cannot be supplied in time before the film breaks, and the resin adheres to the original lubrication state. Therefore, it is an important subject to apply pressure to the molten resin in the long land die and to perform stable extrusion molding.

An object of the present invention is to extrude a resin material comprising a crosslinkable thermoplastic resin and a crosslinking agent having a thermal decomposition temperature higher than the melting temperature of the resin into a long land die,
In an extrusion molding device that generates cross-links in a long land die, a deformation die can be used to apply back pressure to the molten resin in the long land die, and extrusion molding that can be stably extruded for a long time It is to provide a device.

[0008]

The extrusion molding apparatus of the present invention is an extrusion molding apparatus in which a shaping die is connected to the outlet of the extruder and a long land die is connected to the outlet of the shaping die. That is, a lubricant supply unit is provided between the shaping die and the long land die, and at the outlet of the long land die, a cross section in a direction perpendicular to the resin traveling direction of the resin flow path in the long land die and , A deformation die having the same cross-sectional area and different cross-sections is provided.

The extrusion molding apparatus of the present invention will be described below with reference to the drawings. FIG. 1 is a partial cross-sectional view showing an example of the extrusion molding apparatus of the present invention. In FIG. 1, reference numeral 1 is an extruder, which is provided with a shaping die 2 connected to an outlet at the tip of the extruder 1, and with a long land die 3 connected to the shaping die 2. ing. Further, the deformation die 4a is connected to the tip of the long land die 3 to form an extrusion molding device. Further, 5 is a pressure gauge.

A lubricant supply portion 6 is provided at a connection portion between the shaping die 2 and the long land die 3 and is connected to a lubricant supply pump 10 by piping. FIG. 2 is a cross-sectional view showing an example of the lubricant supply unit 6 shown in FIG. 1, in which the lubricant is delivered by the lubricant supply pump 10 and slits from the lubricant introduction port 61a through the lubricant reservoir 62a. It is supplied into the long land die 3 from 63. The size of the gap of the slit 63 is determined by the viscosity of the lubricant used, the amount of withdrawal, etc., but if it becomes narrow, it is difficult to process, and if it becomes wide, the molten resin will enter the slit, so 10 to 500 μm is preferable, and 30 ˜200 μm is more preferred.

FIG. 3 is a sectional view showing another example of the lubricant supply section 6 shown in FIG.
Is discharged from the lubricant introduction port 61b, passes through the lubricant reservoir portion 62b, passes through the porous body 64, and is supplied into the long land die 3. The pore diameter, porosity, and thickness of the porous body 64 are
The pore diameter is preferably 0.1 to 30 μm, more preferably 0.3 to 10 μm, although it is determined by the type and supply amount of the lubricant. The porosity is preferably 10 to 40%, and 1
5 to 30% is more preferable.

In order to uniformly supply the lubricant to the interface between the molten resin and the inner surface of the die, it is preferable that the porous body 64 has a sharp pore distribution and is uniformly dispersed. Examples of the material of the porous body 64 include metallic materials such as gold, silver, platinum, copper, iron, bronze, brass, stainless steel, nickel, and aluminum, as well as alumina, mullite, zirconia, aluminum silicate, and silicon carbide. Non-metal materials such as sintered ceramics are used.

The length of the long land die 3 is determined from the set temperature of the long land die 3, the extrusion molding speed, the thermal conductivity at the molding temperature of the resin, and the decomposition characteristic of the crosslinking agent used. The desired gel fraction cannot be obtained and 3000 cm or more is unnecessary.

A deforming die 4 is provided at the exit of the long land die 3.
a is provided. That is, in the long land die 3, crosslinks are generated under the back pressure applied by the deformation die 4a provided at the outlet of the long land die 3.

In the above-mentioned deformation die 4a, the cross-sectional shape of the resin flow path of the long land die is the same as the cross-sectional shape of the resin flow path at the entrance of the deformation die. The cross-sectional shape of the resin channel is made different. Then, the cross-sectional area S1 in the direction perpendicular to the resin traveling direction of the resin flow path in the long land die and the arbitrary cross-sectional area S2 of the deforming die are made equal.

By making the shape of the deforming die as described above, the back pressure can be applied to the molten resin in the long land die by the elastic deformation resistance of the crosslinked resin, and the accumulation of the lubricant can be prevented.

The cross-sectional shape of the resin flow path of the long land die 3 is not particularly limited, and may be, for example, a tubular shape, a slit shape, a rectangular shape, a corrugated plate shape, or a U-shape. It may have a modified cross section. Furthermore, it may have a cross-sectional shape corresponding to a hollow molded body, a molded body having an undercut portion, or a ribbed molded body.

The cross sectional shape of the resin flow path of the deforming die 4a is not particularly limited, but preferably the cross sectional shape of the long land die is multiplied by C in the vertical direction and 1 in the horizontal direction.
It is better to use / C times. For example, in the case of molding a circular rod-shaped molded product, the cross section of the resin flow path of the long land die has a circular shape with a radius r, and the cross section of the resin flow path of the deformation die has a long diameter Cr and a short diameter r / C. Elliptical (however, C: constant
1.1 to 4); in the case of molding a sheet-shaped molded product, the cross section of the resin flow path of the long land die has a width w,
A rectangular shape having a thickness t, and a cross section of the resin flow path of the deforming die has a width Cw and a thickness t / C (where C: constant 1.1 to 1.1).
4). Also, if the number of deformation dies outside the range of the constant C is
By combining more than one, the same effect as that of the deforming die, that is, back pressure can be applied to the long land die.

The heating method of the long land die 3 for causing the cross-linking reaction is most conveniently performed by electric heating.
Easy temperature control. In addition, heating is long land die 3
Does not need to be the same over the entire area, and may be divided into several zones and performed under optimum temperature conditions for the molding resin.

As the lubricant supplied to the extrusion molding apparatus of the present invention, decomposition or boiling does not occur at the extrusion molding temperature of the resin material used, it does not melt into the molten resin, and further deterioration of the resin material is promoted. Chemically stable ones free from Lubricants suitable for these conditions include, for example, polysiloxanes such as polydimethylsiloxane and polymethylsiloxane; polyhydric alcohols such as ethylene glycol, and alkyl esters and alkyl ethers thereof; polyoxyalkylenes, and alkyl esters and alkyl thereof. Ethers; polyoxyalkylenes and copolymers of two or more kinds of alkylene oxides thereof, and the like. Among them, water-soluble interfaces such as polyhydric alcohols that can be easily removed after adhering to the surface of an extrusion-molded product. Activators are preferred.

As for the supply amount of the lubricant, when the film thickness is 10 μm or less in view of the film thickness, film breakage is likely to occur, and when it exceeds 500 μm, the effect of increasing the amount is reduced, so that the film thickness is 10 to 50.
The amount is preferably 0 μm, and more preferably 50 to 200 μm.

A cross-linkable resin composition comprising a thermoplastic resin and a cross-linking agent is used in the extrusion-molded article molded by the extrusion-molding apparatus of the present invention.

As the above-mentioned crosslinkable thermoplastic resin,
Although not particularly limited, for example, olefin resins such as polyethylene, polypropylene and polybutene; copolymers of olefins; copolymers of olefins with other monomers such as vinyl acetate, acrylic acid and methacrylic acid; vinyl such as vinyl chloride and vinylidene chloride. System homopolymers;
Vinyl-based copolymers such as acrylonitrile, vinyl acetate, vinylidene chloride, and methyl acrylate; diene-based polymers such as styrene-butadiene rubber and natural rubber; styrene-based polymers; amide-based polymers such as 6,6 nylon and nylon 12; polyethylene terephthalate, Examples thereof include thermoplastic polyester-based polymers such as polybutylene terephthalate. These may be used alone or in combination of two or more.

The cross-linking agent is not particularly limited as long as it has a decomposition temperature higher than the softening point of the thermoplastic resin and is suitable for cross-linking the resin. For example, dicumyl peroxide (Japan YUPO Co., Ltd., trade name "Park Mill D"), α, α'-bis (t-butylperoxy-m-
Isopropyl) benzene (trade name “Perbutyl P” manufactured by NOF CORPORATION), α, α′-bis (t-butylperoxy-p-diisopropyl) benzene, 2,5-dimethyl-
2,5-di (t-butylperoxy) hexane-3 (manufactured by NOF CORPORATION, trade name “Perhexin 25b”), t-butylperoxybenzoate (manufactured by NOF CORPORATION, trade name “Perbutyl Z”), t -Butyl cumyl peroxide (manufactured by NOF CORPORATION, trade name "Perbutyl C"), cyclohexane peroxide, cyclohexanone peroxide, 1,1-bis (t-butylperoxy) cyclohexane, 1,1-bis (t-butyl) Peroxy) 3,3
5-trimethylcyclohexane, 2,2-bis (t-butylperoxy) octane, n-butyl-4,4-bis (t-butylperoxy) valerate, di-t-butylperoxide, benzoylperoxide, kumi Ruperoxyneodecanate, 2,5-dimethyl-2,5-
Di (benzoylperoxy) hexane, t-butylperoxyisopropyl carbonate, t-butylperoxyallyl carbonate, t-butylperoxyacetate, 2,2-bis (t-butylperoxy) butane, di-t-butyl Organic peroxides such as peroxyisophthalate, di-t-butyldiperoxyphthalate and t-butylperoxymaleic acid; sulfur; azo compounds such as diazoaminobenzene, N, N'-dichloroazodicarbonamide; trichloromelamine , Halogen compounds such as hexachloropentadiene, trichloromethanesulfochloride and benzotrichloride. Of these, organic peroxides are preferred. These may be used alone or in combination of two or more.

The softening point of the thermoplastic resin means the melting point in the case of a crystalline resin, and the flow starting temperature in the case of an amorphous resin. The melting point is a temperature at which a crystal structure melts and changes to a molten state, and specifically, a differential scanning calorimeter (DS).
When the temperature is gradually raised in C), it means the peak temperature of the endothermic peak.
The flow starting temperature is a state in which a thermoplastic resin filled in an elevated flow tester (capillary diameter 2 mm x length 20 mm) is loaded with a load of 500 kg / cm ^{2 and} the temperature is gradually raised until the thermoplastic resin It is the temperature at which it begins to flow.
Further, the decomposition temperature of the cross-linking agent refers to the temperature at which the half-life is 1 minute.

The amount of these cross-linking agents added should be determined according to the molecular weight of the thermoplastic resin used, the molecular weight distribution, the molecular structure such as the number of branches, the decomposition temperature of the cross-linking agent, and the degree of cross-linking required. However, when the addition amount is small, crosslinking does not occur, and when the addition amount is large, it does not contribute to the crosslinking and remains as a decomposition residue in the extrusion-molded product. Therefore, it is preferably 0.01 part with respect to 100 parts by weight of the thermoplastic resin. -5 parts by weight, more preferably 0.1-2 parts by weight.

A crosslinking aid, a foaming agent, an antioxidant, a crosslinking retarder, a plasticizer, a pigment, a flame retardant, an antistatic agent, etc. are added to the above-mentioned crosslinkable resin composition within the range of not impairing the physical properties. May be.

The above-mentioned crosslinking aid is not particularly limited as long as it is generally used for crosslinking a thermoplastic resin, and for example,
Examples include divinylbenzene, triallyl isocyanate, diethylene glycol diacrylate, trimellitic acid triallyl ester, and the like.

The addition amount of the above-mentioned crosslinking aid varies depending on the crosslinkable thermoplastic resin used, but if it is reduced, it is not effective, and if it is increased, it remains as a residue in the extruded product obtained and the physical properties of the resin are impaired. 0.1 to 5 parts by weight is preferable with respect to 100 parts by weight of the plastic resin.

The above-mentioned foaming agent is generally used in the production of foams, and is not particularly limited as long as it has a decomposition temperature higher than the decomposition temperature of the crosslinking agent, and examples thereof include azodicarbonamide, N, N. There are'-dinitrosopentamethylenetetramine, benzenesulfonylhydrazide, toluenesulfonylhydrazide, azobisisobutyronitrile, N, N'-dimethylN, N'-dinitroterephthalamide, and the amount used deviates from the usual amount. But generally 2 to 100 parts by weight of the thermoplastic resin.
40 parts by weight is preferable, and 5 to 30 parts by weight is more preferable.

The decomposition temperature of the foaming agent means the decomposition temperature at the peak start point when measured by DSC.

The antioxidant is not particularly limited as long as it is generally used, and examples thereof include tetrakis [methylene (3,5-di-t-butyl-4-hydroxyhydrocinnamate)] methane and thiodiene. Examples thereof include dilauryl propionate and 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane. If the added amount of the antioxidant is small, the effect of the antioxidant does not appear, and if the added amount is large, there is an adverse effect such as crosslinking inhibition. Therefore, 0.01 to 0.5 parts by weight relative to 100 parts by weight of the thermoplastic resin is added. Parts are preferred.

The method for producing the above-mentioned crosslinkable resin composition is not particularly limited, and examples thereof include a method in which a thermoplastic resin, a crosslinking agent and the like are supplied to a mixer and blended.

[0034]

In the extrusion molding apparatus of the present invention, a shaping die is provided at the extrusion port at the tip of the extruder, and a long land die is provided at the tip of the shaping die. Since the lubricant supply section is provided between the die and the long land die, and the deformation die is provided at the tip of the long land die, back pressure is applied to the molten resin in the long land die by the deformation die. By suppressing the gas generated when the cross-linking agent decomposes or by thermally decomposing the additive, a smooth cross-linking bond is formed, and it is possible to obtain a void-free extruded product, and a lubricant before the deformation die. Since the accumulation of oil is prevented and the stability of lubrication is ensured, stable extrusion molding can be performed for a long time.

[0035]

EXAMPLES Examples of the present invention will be described below. Example 1 A sheet-shaped extrusion-molded article was extruded using the extrusion-molding apparatus shown in FIG. The shaping die 2 had an outlet cross-sectional shape of 5 mm × 200 mm, and the long land die 3 had a resin flow path cross-sectional shape of 5 mm × 200 mm and a length of 150 cm. The deforming die 4a used had a resin flow passage cross-sectional shape of 2.5 mm × 400 mm at the outlet. A lubricant supply slit portion 6 having a clearance of 50 μm, which communicates with the resin passage, is provided between the shaping die 2 and the long land die 3, and the lubricant supply slit portion 6 is provided.
Therefore, the lubricant can be supplied at 5 cc / min by the lubricant supply device 10 provided outside. The lubricant is polyalkylene glycol (trade name: Nissan Unilube 75D-3800 manufactured by NOF CORPORATION).
Z) was used.

As the crosslinkable resin composition, a low density polyethylene resin (trade name: G201, manufactured by Sumitomo Chemical Co., Ltd., melting point 1
A mixture of 100 parts by weight of (07 ° C.) and 0.6 parts by weight of dicumyl peroxide (decomposition temperature of 171 ° C.) was used. Using the extruder 1 having a screw diameter of 50 mm and L / D = 22, the crosslinkable resin composition was extruded at an extrusion rate of 5 kg / hr. The resin temperature in the shaping die 2 at this time is 125 ° C.
Met. Also, the set temperature of the long land die is 160 ℃.
And As a result, there was no uneven flow or adhesion of the resin due to fluctuation of the resin back pressure or breakage of the lubricant film, and a molded product could be obtained stably. The obtained molded product has a thickness of 4.5 mm and a width of 2
A void-free sheet-shaped molded product having a diameter of 05 mm, a gel fraction of 57% and a density of 0.92 g / cm ³ was obtained.

(Example 2) As a crosslinkable resin composition, a high-density polyethylene resin (trade name: JX2 manufactured by Mitsubishi Petrochemical Co., Ltd.) was used.
0, melting point 138 ° C.) and 100 parts by weight of dicumyl peroxide (decomposition temperature 171 ° C.) 0.8 parts by weight were added and mixed. The article was extruded. The resin temperature in the shaping die 2 at this time was 143 ° C. As a result, there was no uneven flow or adhesion of the resin due to fluctuations in the resin back pressure or breakage of the lubricant film, and a molded product could be obtained stably and continuously.
The obtained molded product was a sheet-shaped extrusion molded product having a thickness of 4.4 mm × a width of 205 mm, a gel fraction of 55% and a density of 0.96 g / cm ³ .

(Embodiment 3) The resin mold of the shaping die 2 has a circular cross section with a diameter of 10 mm, and a long land die 3 is used.
The resin flow path cross-section of is a circular shape with a diameter of 10 mm, the length is 2000 mm, and the exit resin flow path cross section of the deforming die 4a is an elliptical shape with a major axis of 20 mm and a minor axis of 5 mm. / Hr and the lubricant supply rate was 1 cc / min. Extrusion molding was performed in the same manner as in Example 1. The resin temperature in the shaping die 2 at this time is 125 ° C.
Met. As a result, there was no uneven flow or adhesion of the resin due to fluctuations in the resin back pressure or breakage of the lubricant film, and a molded product could be obtained stably and continuously. The obtained molded product has a diameter of 10 m.
It was a rod-shaped extrusion-molded product having m, a gel fraction of 58% and a density of 0.92 g / cm ³ .

Comparative Example 1 Extrusion molding was carried out in the same manner as in Example 1 except that the deforming die 4a was not used.
As a result, the obtained molded product has a thickness of 5 mm and a width of 197 m.
It was a sheet-like extruded product containing voids having m, a gel fraction of 55% and a density of 0.88 g / cm ³ . Comparative Example 2 A sheet-shaped extrusion-molded article was extruded using the extrusion-molding apparatus shown in FIG. Deformation die 4a
Instead, a drawing die 4b with a drawing ratio of 0.5 is used (the resin flow path cross-sectional shape of the minimum cross-sectional area portion of the drawing die is 3.5 mm ×
(It was a rectangle of 140 mm), except that the lubricant removal section 8 was provided in front of the drawing die 4b, and the pressure control system 14 was provided between the pressure gauge 5 and the lubricant removal section 8.
Extrusion molding was performed in the same manner as in Example 1. In addition, 9 is a valve. As a result, the resin pressure is 27-35 kg / cm
^It periodically fluctuated between ² and the resin pressure drastically increased about 1 hour and 30 minutes after the start of extrusion, and the resin stayed in the drawing die part, and the desired sheet molded product could not be obtained.

[0040]

EFFECT OF THE INVENTION Since the extrusion molding apparatus of the present invention is constructed as described above, it is possible to continuously form a void-free extrusion molded article which is free of resin adhesion and uneven flow. .

[Brief description of drawings]

FIG. 1 is a partially cutaway sectional view showing an example of an extrusion molding apparatus of the present invention.

FIG. 2 is a detailed cross-sectional view of a lubricant supply unit.

FIG. 3 is a detailed cross-sectional view showing another example of the lubricant supply section.

FIG. 4 is a partially cutaway sectional view of an extrusion molding apparatus used in Comparative Example 2.

[Explanation of symbols]

 1 Extruder 2 Molding die 3 Long land die 4a Deformation die 6 Lubricant supply section

Claims (1)

[Claims] 1. A molding die is connected to an outlet of the extruder,
An extrusion molding device in which a long land die is connected to the outlet of the shaping die, a lubricant supply unit is provided between the shaping die and the long land die, and the outlet of the long land die is provided. An extrusion molding apparatus, wherein a deformation die having a cross section in a direction perpendicular to a resin traveling direction of a resin flow path in a long land die and a cross section having the same cross-sectional area and different shape is provided.