JPH07178791A - Mold - Google Patents

Abstract

PURPOSE:To provide a mold capable of molding an extrusion molded product having no wavy undulation or dimensional irregularity on the surface thereof and having no lubricant remaining on the surface thereof by uniformly extracting the lubricant on this side of a throttle die and preventing the film cutting and accumulation of the lubricant. CONSTITUTION:A lubricant supply part 15 is provided in the vicinity of the inlet of a long land die 13 so as to be capable of supplying a lubricant to a resin passage 131. A lubricant extracting part 16 is provided in the vicinity of the outlet of the long land die 16 so as to be capable of extracting the lubricant from the resin passage 131. The cross section of the resin passage immediately after the lubricant extracting part 16 is made larger than that of the resin passage 131 immediately before the lubricant extracting part 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold used for molding an extruded product made of a building material such as a lining material, a waterproof material and a heat insulating material, and a crosslinkable resin material such as a plate and a foam. Is.

[0002]

2. Description of the Related Art Conventionally, as a method of continuously extruding a crosslinkable resin material to form an extrusion molded article, as described in JP-A-48-96656, a crosslinkable molding material is used at a certain temperature and at a certain temperature. When an extruded product is obtained by extruding from a die device having a land portion of a length, a sufficient amount of lubricant is present at the interface between the inner mold of the land portion and the molding material or molding product passing therethrough in the vicinity of the base of the land portion. Supply
A method has been proposed in which the lubricant is sucked and removed in the vicinity of the tip of the land portion.

According to this method, the temperature and length of the long land die are set so that the crosslinking reaction of the crosslinkable resin material passing therethrough is completed, and crosslinked molded articles are continuously obtained from the land portion outlet. is there. In this method, a high back pressure is applied to the plasticizing zone of the crosslinkable molding material based on the existence of the long land die in the molding process, so that the long land die inner wall and the crosslinkability passing therethrough are crosslinked. A method has been adopted in which a lubricant is supplied to the interface between the molding material or the molded product to reduce the frictional resistance between the inner wall of the long land die and the crosslinkable molding material or the molded product.

However, according to this method, the cross-linking agent generates a gas at the time of decomposition, so that a void is generated in the molded product. Further, as a method for suppressing the gas generated in the step of forming a crosslink bond by applying a pressure to the molten resin, for example, as described in JP-A-62-121122, a crosslinkable thermoplastic resin, a foaming agent and a resin can be used. When a cross-linking agent having a thermal decomposition temperature higher than the melting temperature of is mixed and extruded from a die device having a long land die of a certain temperature and a certain length to foam the cross-linking agent, the die from the vicinity of the entrance of the long land die In addition to supplying a sufficient amount of lubricant to the sliding portion between the long land die and the molten resin, a drawing die is provided in the middle of the sliding portion between the front stage and the rear stage of the long land die. The back pressure of the molten resin is controlled by applying back pressure to the molten resin and adjusting the removal amount of the lubricant intervening in the sliding part between the die and the molten resin according to the level of the back pressure of the molten resin. A way to do That.

In this method, a drawing die is provided between the front stage and the rear stage of the long land die, and a pressure is applied to the molten resin in the long hand in the front stage so that part of the foaming agent is removed. A method of preventing volatilization or dispersion and further removing the lubricant accumulated in front of the drawing die depending on the level of the back pressure is adopted.

[0006]

However, in the mold used in this molding method, since the lubricant is removed by the slit, it is difficult to maintain the parallelism of the clearance if the clearance of the slit is narrowed. The lubricant cannot be uniformly extracted from the entire circumference of the resin, and the film of the lubricant is broken, resulting in deterioration of lubrication stability such as uneven flow of the resin and increase of back pressure.

On the contrary, if the clearance is widened, the resin enters the slits and blocks the slits, so that the lubricant may not evenly or completely escape. Therefore, it is an important subject to uniformly remove the lubricant before the drawing die to prevent the lubricant from being broken and accumulated.

The present invention solves the above-mentioned conventional problems, uniformly withdraws the lubricant in front of the drawing die, prevents film breakage and accumulation of the lubricant, and causes wavy undulations on the surface and variations in dimensions. The present invention has been made for the purpose of providing a metal mold capable of forming an extrusion-molded article having no surface and no lubricant remaining on the surface.

[0009]

Means for Solving the Problems In the mold of the present invention, a long land die is connected to the outlet of the shaping mold, and a drawing die is connected to the exit of the long land die. The resin flow path is formed so as to communicate with each other, the cross-linkable resin material is extruded from the shaping mold into the resin flow path of the long land die, and the lubricant is supplied over the entire circumference of the cross-linkable resin material passing through the resin flow path. In addition, a structure for molding an extrusion molded product is provided.

The length of the long land die is determined by the crosslinkable resin material used, the inner diameter or thickness of the extruded product, the set temperature, the molding speed, the thermal conductivity of the resin flow path surface, etc., but usually 50 to 3 It is preferably 1,000 cm, more preferably 100 to 1,500 cm. If the length is less than 50 cm, it is difficult to obtain an extrusion-molded product having a desired gel fraction. On the contrary, if the length exceeds 3,000 cm, not only is the equipment excessive, but the workability is rather deteriorated.

The cross-sectional shape of the resin passage is not particularly limited, and may be, for example, a tubular shape, a slit shape, or a different shape such as a rectangular shape, a corrugated plate shape, and a U-shape. Good. Further, 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 resin flow path surface is made of, for example, aluminum, stainless steel, titanium, gold, silver, a metal material having good thermal conductivity such as a cylinder, alumina, mullite, silicic acid,
It is preferable to use a porous material such as a non-metallic material mainly containing zirconia and the like, on the surface of which a coating layer such as a fluororesin having a small surface energy is formed.

As a heating means for accelerating the crosslinking reaction of the crosslinkable resin material passing through the resin flow path in the long land die, generally any heating means is used, but the simplest heating method is heating conditions. Is easy to control. The temperature conditions do not have to be the same over the entire length of the long land die, and it is preferable to divide the zone into several zones and set the temperature and heating conditions most suitable for the crosslinkable resin material.

The crosslinkable resin material used in the present invention may be any crosslinkable resin material, for example, aminoblast, phenoblast, epoxy resin,
Examples thereof include unsaturated polyester resins, other thermosetting resins, crosslinkable thermoplastic resins containing a crosslinking agent, and natural rubber.

Examples of the thermoplastic resin include polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyamide, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer and the like. These may be used alone or in combination of two or more.

Further, additives such as synthetic rubber, paraffin, plasticizer, pigment, foaming agent, flame retardant and antistatic agent may be mixed with these thermoplastic resins. In addition, any resin that causes a crosslinking reaction by heating, such as a methylol acrylamide polymer, a metal oxide-containing carboxylic acid polymer, or an unsaturated polyester, can be used.

The cross-linking agent has a decomposition temperature not lower than the melting temperature of the thermoplastic resin, and may be appropriately selected from those suitable for cross-linking the resin, for example, dicumyl peroxide, t-bral peroxide, and the like. t-butyl cumyl peroxide, diisopropylbenzene hydroperoxide, α, α '(bis-t-butylperoxy-p
-Diisopropyl) benzene, 2,5-dimethyl-2,
Examples thereof include organic peroxides such as 5-di- (butylperoxy) hexane. These may be used alone,
Also, two or more kinds may be used in combination.

The amount of these crosslinking 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 crosslinking agent, and the degree of crosslinking required. However, it is preferably 0.1 to 10% by weight, and more preferably 0.2 to 2% by weight. If the amount added is too small, crosslinking will not occur, while if it is too large, it will remain as a decomposition residue in the molded product without contributing to crosslinking.

As the lubricant, decomposition and boiling are less likely to occur at the molding temperature of the crosslinkable resin material used, and the lubricant does not melt into the crosslinkable resin material and further accelerates the deterioration of the crosslinkable resin material. Not a chemically stable substance is preferred.

Specific examples of such a lubricant include, for example, liquid polysiloxane (polydimethylsiloxane,
Polymethylsiloxane, etc.), polyhydric alcohols such as ethylenegtacol, and their alkyl esters and alkyl ethers, polyoxyalkylenes and copolymers of two or more kinds of alkylene oxides. Of these, water-soluble surfactants such as polyhydric alcohols, which are easy to remove after adhering to the surface of the extruded product, are preferable.

The supply amount of the lubricant is such that the film thickness is 10 to 500 μm.
The amount is preferably m, and particularly preferably the amount is 50 to 200 μm. If the film thickness is less than 10 μm, film breakage is likely to occur, and conversely, if the film thickness exceeds 500 μm, excessive lubricant tends to be localized, causing drift.

Further, in the mold of the present invention, a lubricant supply section is provided near the entrance of the long land die so as to be able to supply the lubricant to the resin flow path, and the lubricant is supplied from the resin flow path near the exit of the long land die. The cross section of the resin flow path immediately after the lubricant removal part is larger than the cross section of the resin flow path immediately before the lubricant removal part.

The lubricant supply section is provided near the inlet of the long land die, but it may be provided between the shaping die and the long land die, or may be provided at the inlet of the long land die. Alternatively, it may be provided at the outlet of the shaping mold.

The structure of the lubricant supply part is not particularly limited, but one example is a structure in which the lubricant is press-fitted into the resin flow path from the slit, more specifically, the supply port and the lubricant. A structure in which a lubricant is continuously or discontinuously pressed into the resin flow path by a pump from a slit that opens into the resin flow path through the reservoir to press-fit between the resin flow path surface and the molten resin passing therethrough is provided. I will give you. Further, as another structure of the lubricant supply part, the resin flow path surface is formed of a porous body such as a metal sintered body or ceramics, and the lubricant is press-fitted into the resin flow path through the pores of the porous body. Etc.

The lubricant removing portion is provided near the exit of the long land die, but it may be provided between the long land die and the drawing die, or may be provided at the exit portion of the long land die. It may be provided at the entrance of the drawing die.

The structure of the lubricant removing portion is not particularly limited, but as an example, the structure for extracting the lubricant from the slit, more specifically, the lubricant from the slit opening to the resin flow path is used. Examples include a structure in which the lubricant that is present between the resin flow path surface and the molten resin passing therethrough is extracted by sucking the lubricant continuously or discontinuously with a pump through the reservoir and the discharge port.

The clearance of the slit may be determined in consideration of the viscosity of the lubricant used, the amount of withdrawal, etc.
0 to 500 μm is preferable, and 30 to 200 μm is more preferable. If the clearance is less than 10 μm, it is difficult to form the slit, and conversely, if it exceeds 500 μm,
Molten resin gets into the slit.

In the present invention, it is necessary that the cross-sectional area S ₂ of the resin flow channel immediately after the lubricant draining portion is larger than the cross-sectional area S ₁ of the resin flow channel immediately before the lubricant draining portion. , the degree, S ₂ / S ₁ is 101 / 100-150
It is preferably / 100.

In the present invention, the resin flow path communicating with the long land die is extended in the drawing die, but the drawing part is provided at the substantially central portion, and the cross-sectional area S ₃ of the drawing part is the inlet. Is smaller than the cross-sectional area S _{2 of the} outlet and the outlet,
The degree of S ₃ / S ₂ is preferably in the range of 10/100 to 90/100, and 35/100 to 85/10.
It is more preferably within the range of 0.

The present invention will be described below with reference to the drawings.
FIG. 1 is a sectional view showing an example of the mold of the present invention. The mold 1 is a shaping mold 12, a long land die 13, and a drawing die 14.
Consists of. A shaping die 12 is provided at the exit of the extruder 11. A long land die 13 is provided on the outlet side of the shaping die 12.
Are connected. A diaphragm die 14 is connected to the exit of the long land die 13. A resin flow path 131 and a resin flow path 141, through which the molten resin passes, are formed in the long land die 13 and the drawing die 14, respectively.

The surfaces of the resin flow paths 131 and 141 are made of a porous body made of a metal material having a high thermal conductivity such as alumina, and a coating layer made of a fluorine resin having a small surface energy provided on the porous body.

As shown in FIG. 3, the resin flow path 141 of the drawing die 14 is formed with a drawing portion 141b at a substantially central portion, and its sectional area S ₃ is a sectional area S _{2 of the} inlet portion 1141a.
Has been made smaller than.

A lubricant supply section 15 is provided between the shaping die 12 and the long land die 13. As shown in FIG. 2 (see FIG. 1), the lubricant supply section 15 is provided with a slit 151 that communicates with the resin flow path 131 of the long land die 13. Then, from the slit 151, from the lubricant supply device 18 and the pump 17 provided outside,
The lubricant supplied through the lubricant supply path 154, the lubricant supply port 153, the lubricant reservoir 152, and the slit 151 can be press-fitted into the resin flow path 131 of the long land die 13.

A lubricant removing portion 16 is provided between the long land die 13 and the drawing die 14. As shown in FIG. 3 (see FIG. 1), the lubricant removal portion 16 has a slit 161 communicating with the resin flow path 131 of the long land die 13.
Is provided. Then, by the operation of the pump 17,
From the slit 161, the gas lubricant that is present between the surface of the resin flow path 131 and the molten resin is transferred to the lubricant reservoir 16
2, lubricant outlet 183, valve 19, lubricant outlet 1
After being sucked through 64, it can be discharged by being sucked continuously or discontinuously, and can be circulated by the pump 17.

As shown in FIG. 3, the resin flow of the drawing die 14 immediately after the lubricant withdrawing portion 16 is larger than the cross-sectional area S ₁ of the resin flow path 131 of the long land die 13 just before the lubricant withdrawing portion 16. The cross-sectional area S ₂ of the entrance 141a of the passage 141 is made larger.

An example of an embodiment using the mold shown in FIG. 1 will be described below with reference to FIG. First, the crosslinkable resin material is supplied to the extruder 11, melted and kneaded therein, and the molten resin is extruded from the outlet of the shaping die 12 into the resin flow path 131 in the long land die 13.

Next, the pump 17 supplies the lubricant to the circulating agent supply port 153 of the lubricant supply section 15 and the lubricant reservoir section 152.
Then, the molten resin 2 is passed through the resin flow path 131 while being supplied to the resin flow path 131 from the slit 151. At this time, the molten resin 2 passing through the resin flow passage 131 is evenly adhered to the surface of the resin flow passage 131 because the entire outer periphery thereof is covered with the lubricant.

At the same time, the molten resin 2 passing through the resin flow path 131 is heated by the heating means to decompose the cross-linking agent and cross-link the resin. At this time, the molten resin 2 uniformly flows through the resin flow path 131 of the long land die 13, so that the heating and
Crosslinking is also performed uniformly.

Then, from the slit 161 of the lubricant removing portion 16 provided between the outlet of the long land die 13 and the drawing die 14, the lubricant reservoir 162 and the lubricant outlet 16 are provided.
After 3, the pump 17 sucks and removes the lubricant.
The extracted lubricant is supplied from the pump 17 to the lubricant supply unit 15
And circulate as appropriate.

Next, the molten resin 2 that has passed through the resin flow path 131 in the long land die 13 is guided to the resin flow path 141 in the drawing die 14, and the molten resin is drawn in a substantially central portion of the drawing die 14. Back pressure is applied to the molten resin 2 passing through the resin flow path 131 of the long land die 13 by passing the portion 141b. Finally, the extruded product 3 is obtained by discharging from the outlet.

At this time, the resin flow path 1 of the long land die 13
The molten resin 2 to which the back pressure of 31 is applied is taken as the lubricant removing portion 16
Than the cross-sectional area S ₁ of the resin flow path 131 of the long land die 13 immediately before the drawing die 14 immediately after the lubricant withdrawing portion 16.
Of the slit 1 of the lubricant removing portion 16 by passing through the portion provided with the lubricant removing portion 16 in which the cross-sectional area S ₂ of the inlet portion 141a of the resin flow path 14 is larger.
Since the lubricant collects near the inlet of 63, the slit 163
Therefore, the lubricant in the resin flow path 131 of the long land die 13 can be stably and uniformly extracted.

In the molten resin from which the lubricant has been extracted after passing through the lubricant extracting portion 16, the surface resistance with the resin flow passage surface increases or decreases due to the increase or decrease in the amount of the lubricant extracted from the lubricant extracting portion 16. Therefore, the back pressure of the molten resin passing through the resin flow path 131 of the long land die 13 is increased or decreased accordingly. Therefore, for example, when the resin back pressure of the molten resin passing through the resin flow path 131 of the long land die 13 sensed by the resin pressure gauge becomes higher than a desired set pressure, the lubricant removal section 16 is provided. By providing a response system that narrows or closes the opening of the valve, it is preferable to have a structure that enables stable control of the resin back pressure and does not increase the back pressure more than necessary.

[0043]

In the mold of the present invention, a long land die is connected to the outlet of the shaping mold, a drawing die is connected to the exit of the long land die, and a resin flow path is communicated with the long land die and the drawing die. The extruded product is formed by extruding the crosslinkable resin material from the shaping die into the resin channel of the long land die and supplying the lubricant all around the crosslinkable resin material passing through the resin channel. A mold to be molded.A lubricant supply part is provided near the entrance of the long land die to supply the lubricant to the resin flow path, and the lubricant can be removed from the resin flow path near the exit of the long land die. Since the cross section area of the resin flow path immediately after the lubricant removal section is larger than the cross section area of the resin flow path immediately before the lubricant removal section, the long land die The molten resin that passes through the resin flow path Since the entire outer circumference is covered with a lubricant, it can pass through without adhering to the resin flow path surface and causing uneven flow, and can uniformly heat and crosslink it. Back pressure is applied to the molten resin that passes through the resin flow path, and the cross-sectional area of the resin flow path changes at the lubricant removal part, so that the lubricant can be collected near the inlet, and the long distance from the lubricant removal part Manufactures extruded products that can stably and evenly remove the lubricant that passes through the resin flow path of the shaku land die, has no wavy undulations on the surface and does not have dimensional variations, and has no lubricant remaining on the surface. It can be preferably used as a mold for forming.

[0044]

EXAMPLES Examples of the present invention will be described below. Example 1 Using a mold 1 as shown in FIGS. 1 to 3, a board-shaped extruded product was extruded by the embodiment described with reference to FIG. As the shaping die 12, the cross section of the outlet is 2 × 2
The one of 00 mm was used. As a long land die 13,
A resin flow path having a cross section of 5 × 200 mm and a length of 1.5 m was used.

As a drawing die, the drawing ratio S ₂ / S ₃ is 10
/ 7, the inlet section 141a of the resin flow channel 141 corresponding to the position immediately after the lubricant withdrawing section 18 had a cross section of 7 × 200 mm. Therefore, the ratio S ₁ / S ₂ of the cross-sectional area S ₁ of the resin flow channel immediately before the lubricant removal portion and the cross-sectional area S ₂ of the resin flow channel immediately after the lubricant removal portion in this mold is 5/7. Has become.

As the crosslinkable resin material, low-density polyethylene (manufactured by Sumitomo Chemical Co., Ltd., trade name "High-pressure polyethylene G20") is used.
1 ") 100 parts by weight, cross-linking agent (dicumyl peroxide) 0.1 part by weight, foaming agent (azodicarbonamide) 1
What added 5 weight part was used. As the lubricant, polyalkylene glycol (manufactured by NOF CORPORATION, trade name “Nissan Unilube 75D-3800Z”) was used, and the supply rate was 5 cc / min.

A crosslinkable resin material was extruded at an extrusion rate of 5 kg / hour using an extruder having a diameter of 50 mm. The resin temperature in the shaping die 11 at this time was 125 degreeC.
The set temperature of the long land die 13 was 165 ° C. or,
A resin pressure gauge and a valve were used as a pressure control system, and the valve was adjusted to close when the resin pressure exceeded 25 kg / cm ² .

As a result, there was no uneven flow or adhesion of the molten resin due to the breakage of the lubricant film, and an extruded product could be stably and continuously obtained. The obtained sheet-shaped extruded product had a thickness of 5 mm x a width of 195 mm, a gel fraction of 59% and a density of 0.92.
It did not contain g / cm ³ voids.

Example 2 As a crosslinkable resin material, 100 parts by weight of high density polyethylene (trade name "JX20" manufactured by Mitsubishi Petrochemical Co., Ltd.) was added with 1.0 part by weight of a crosslinking agent (dicumyl peroxide). Extrusion molding of a sheet-shaped extruded product was performed in the same manner as in Example 1 except that the above was used. Shaped mold 12 at this time
The resin temperature was 142 ° C.

As a result, there was no uneven flow or adhesion of the molten resin due to film breakage of the lubricant, and a stable extruded product could be obtained. The obtained sheet-shaped extruded product had a thickness of 5 mm x a width of 197 mm, a gel fraction of 55% and a density of 0.96.
It did not contain g / cm ³ voids.

COMPARATIVE EXAMPLE 1 Example 1 except that a die not connected with a drawing die was used.
Extrusion molding of a sheet-shaped extrusion molded article was performed in the same manner as in. The resulting extruded product has a thickness of 5 mm and a width of 1
It contained 97 mm, a gel fraction of 55%, and a void having a density of 0.88 g / cm ³ .

Comparative Example 2 As a drawing die, the drawing ratio S ₂ / S ₃ is 7/7, and the cross section of the inlet part 141a of the resin flow channel 141 corresponding to the position immediately after the lubricant withdrawing part 18 is 5 × 200 mm. Extrusion molding of a sheet-shaped extruded product was performed in the same manner as in Example 1 except that the above was used. As a result, the resin pressure gradually increased immediately after the start of extrusion, and the molten resin was unevenly flowed and fitted. As a result of disassembling the mold after stopping the extrusion, adhesion of the molten resin was observed immediately after the lubricant removal slit.

[0053]

EFFECT OF THE INVENTION Since the mold of the present invention is constructed as described above, it is used as a mold for producing an extruded product having no wavy undulations on the surface and no variation in dimensions and no lubricant remains on the surface. It can be used preferably.

[0054]

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a mold of the present invention.

FIG. 2 is an enlarged cross-sectional view showing the vicinity of a lubricant supply unit of the mold shown in FIG.

FIG. 3 is an enlarged cross-sectional view showing the vicinity of a lubricant removing portion of the mold shown in FIG.

FIG. 4 is a cross-sectional view illustrating an example of usage of the mold shown in FIG.

[Explanation of symbols]

 1 Mold 11 Extruder 12 Shaped Mold 13 Long Land Die 14 Drawing Die 15 Lubricant Supply Part 16 Lubricant Extraction Part 151,161 Slit 152,162 Lubricant Reservoir 153 Lubricant Supply Port 154 Lubricant Supply Channel 163 Lubricant outlet 164 Lubricant outlet 17 Pump

Claims (1)

[Claims] 1. A long land die is connected to the exit of the shaping die, a drawing die is connected to the exit of the long land die, and a resin flow path is formed so as to communicate with the long land die and the drawing die. A mold that extrudes a crosslinkable resin material from a shaping mold into the resin flow path of a long land die, and forms an extrusion molded product while supplying a lubricant all around the crosslinkable resin material that passes through the resin flow path. There is a lubricant supply part near the entrance of the long land die that can supply the lubricant to the resin flow path, and a lubricant removal part near the exit of the long land die that allows the lubricant to be extracted from the resin flow path. A mold provided, wherein the cross-sectional area of the resin flow channel immediately after the lubricant draining portion is larger than the cross-sectional area of the resin flow channel immediately before the lubricant draining portion.