JP3098376B2 - Method for producing foamed laminated sheet of styrenic resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a foamed laminated sheet of a styrene resin.

[0002]

2. Description of the Related Art Styrene resin foam sheets have been produced by extrusion foaming. The foam sheet made by extrusion foam always had a high-density skin on its surface. This is because when the foamable styrenic resin is extruded from a die, the extruded resin is cooled by contacting the surface with air, so that the surface cannot be foamed at a high magnification like the inside, so that the surface is covered with a skin. Is formed.

A method for producing a laminate of a foamed sheet of a styrenic resin is described in PCT Patent Application No. WO 92/08610 published May 29, 1992. However, the method taught by this gazette is to extrude and foam unused styrene-based resin into a foamed sheet, and also extrude and foam separately the styrene-based resin recovered by recycling to form a foamed sheet. Then, the two foam sheets are bonded together. Therefore, in the laminated foamed sheet obtained by the teaching of this publication, the skins formed on the respective foamed sheets are adhered to each other inside the laminated foamed sheet, and therefore, a non-foamed layer is included inside. Therefore, this laminated foam sheet not only has a bad appearance, but also has a poor feel,
In addition, inconvenience arises in processing when the sheet is heated and formed.

On the other hand, for laminating non-foamed resin sheets, a co-extrusion method is employed. What is co-extrusion?
Thermoplastic resins having different compositions are put into separate extruders and melted, and the molten resins are separately put into the same one die, each resin is separately formed into a sheet, and then merged in the same die. This is a method of fusing them together and extruding them as a laminate from one die. Although this method appears to be applicable in theory to foamed sheets, it was not used to make a laminate of foamed sheets in practice.

[0005] The co-extrusion method was not used to make a laminate of foamed sheets because the resin contained a foaming agent to form a foamable composition. The foamable composition is different from the non-foamed composition in that when mixed in a die, undesired mixing occurs and does not form an orderly layer, and the melt viscosity varies depending on the type and amount of the foaming agent contained. This is because the expansion ratio greatly changes even when the melt viscosity is slightly changed and the melt viscosity is slightly changed. In an extreme case, the expansion may not be performed. For this reason, the co-extrusion method has not been used to produce a laminate of foamed sheets.

[0006]

SUMMARY OF THE INVENTION The inventor of the present invention has made a laminate of a foamed sheet made of a styrene resin and having no low-foaming layer such as leather at the joint of each foamed sheet. I tried to do it. To that end, the inventors have attempted to make this laminate by a co-extrusion method.

[0007]

SUMMARY OF THE INVENTION The inventor of the present invention has proposed that a foamable resin composition can be formed even if the foamable resin composition is merged in a base as long as a styrene resin is used as the resin and a base having a cylindrical gap is used. It was confirmed that an undesired mixing did not occur in the conductive resin composition, and that an orderly layered molded product was obtained. In addition, it has been found that when this is done, the low-foamed skin is eliminated at the joint of the foamed sheets, and a good laminated foamed sheet of a styrene resin can be obtained. Furthermore, since this laminated foam sheet is cylindrical in shape, if the tube is crushed while the inner surface is still hot, the inner surfaces are fused together and a thick laminated foam can be obtained here. I found it. The present invention has been completed based on such knowledge.

The present invention uses a die having a cylindrical gap.
There, this included a foaming agent, followed by circular columnar or circular tubular to a common axis of each resin were placed separately to said one of the base with melting respectively different styrene resin compositions in separate extruder molded into Jo, then a plurality of layers circular cylindrical laminate consisting of foamable resin is combined in the same die, and foamed by extruding from a nozzle in the form, the inner surface of the foamed tubular laminate is still softened The present invention relates to a method for producing a foamed laminated sheet of a styrene resin, characterized in that a cylindrical laminated body is crushed and the inner surfaces are fused together to form a laminated foamed sheet.

In the present invention, a styrene resin is used. The styrene-based resin is not limited to a homopolymer of styrene or a derivative thereof, but includes a copolymer of styrene or a derivative thereof with another monomer, and a graft polymer.
Here, the styrene derivative is, for example, α-methylstyrene, chlorostyrene and the like. Further, the styrene or styrene derivative copolymer is, for example, styrene or α-
It is a copolymer of methylstyrene and acrylonitrile, butadiene, methyl acrylate, maleic anhydride, methacrylic acid or methacrylic acid ester. The graft polymer is, for example, one obtained by graft-polymerizing styrene to an acrylonitrile-butadiene copolymer. In these copolymers or graft polymers, it is necessary that styrene or a styrene derivative accounts for 50% by weight or more.

These homopolymers, copolymers and graft polymers can be used by mixing them, or can be used by mixing with other resins such as a compatible resin such as polyphenylene ether. . Furthermore, these styrenic resins may be a collection of defective products produced in a molding process such as extrusion molding, air pressure molding, etc., or may be those collected after being used as food containers in the market. Good.

In the present invention, styrene resins having different compositions are used. Here, it is needless to say that the difference in the composition includes the case where the styrene-based resin itself is different. However, even if the styrene-based resin itself is the same, only the dye, the pigment and other additives are different. This includes the case where one is an unused styrene resin and the other is the recovered styrene resin described above. In other words, different compositions mean resin compositions that cannot be kneaded with the same single extruder.

In the present invention, an extruder is used. The extruder is
A rotatable screw is installed in a barrel that can be heated, and a mechanism that heats and melts the styrene resin and extrudes the styrene resin from a die attached to the end of the barrel. As the extruder, one screw and two screws are often used, but in the present invention, one screw, that is, a single screw extruder is preferably used.

In the present invention, a blowing agent is contained in the styrene resin melted in the extruder. For that purpose, a pressure inlet for the foaming agent is provided in the middle of the barrel constituting the extruder,
From there, a foaming agent is injected. The resin melted by the injection of the foaming agent is provided with foaming properties. The foamed resin melt is then cooled to a temperature suitable for foaming. This cooling is preferably performed in an extruder. Therefore, in the present invention, it is preferable to use a commonly used tandem extruder to obtain a foamable melt. A tandem extruder is an extruder having a structure in which two extruders are vertically connected. In the tandem extruder, a resin is melted in a first extruder, and a foaming agent is press-fitted to form a foamable resin melt. The melt at the appropriate foaming temperature is extruded from a die attached to the tip of the extruder 2 to obtain a foam.

In the present invention, resins having different compositions are melted in different extruders, respectively, and then a foaming agent is added thereto to form a foamable resin melt. For example, one tandem extruder is used to make a foamable melt of virgin resin, and another tandem extruder is used to make a foamable melt of recovered resin. Thus, the extruder requires a series of extruders corresponding to the number of resins having different compositions.

In the present invention, as described above, a plurality of extruders need to be provided, but only one extruder is used. For this reason, foamable melts made in multiple series,
Both are put separately in the base. Initially, they are separately formed into a column or a cylinder in the base, but these columns or cylinders have a common axis. Columns or cylinders having a common axis are then merged in the same die to form a cylindrical laminate. Such a die is generally called a circular die and is used to make a laminate of a non-foamed resin. The die used in the present invention is basically the same as a circular die that has been used to form a cylindrical laminate by laminating non-foamed resins.

As shown in FIG. 1, the base used in the present invention preferably comprises a front end 22 and a junction 21. The tip portion 22 is a portion that functions to adjust the molten resin into a desired cross-sectional shape and discharge the resin from the die. The merging section 21 receives the expandable melts sent from the plural series of extruders 1 and 2 from separate inlets 31 and 32, and initially forms each melt separately into a coaxial cylinder or cylinder. Then, a portion formed into a column or a cylinder at the outlet side 30 is merged to form an integrated laminate. The merging section 21 sends the laminate to the front end after forming the laminate.

In the mouthpiece composed of the tip 22 and the junction 21, the foamed resin laminated when exiting the junction 21 is shown in FIG.
Is formed into a columnar shape as shown in FIG. 3, the cylindrically shaped product enters the tip portion 22 and collides with the torpedo 221 to form a hole at the center, and is laminated as shown in FIG. 3. It is preferable to be formed in a cylindrical shape and to be discharged from the tip portion 22 in this form.

In the present invention, it is preferable to provide a melt pump between the extruder and the die. The melt pump is a gear pump for transporting a melt of the foamable resin at a constant rate. The use of a melt pump ensures that the foamable melt from the extruder is sent to the die at a constant rate.

The present invention differs from laminating non-foamed resins in that the styrene-based resin contains a foaming agent and is a foamable melt. As the foaming agent, a volatile foaming agent is used. A volatile foaming agent is a gas or liquid with a boiling point lower than the softening point of the resin, which dissolves in the molten resin under pressure, but has the property of volatilizing from the molten resin under normal pressure due to its low solubility. It is a gas or liquid that you have. Such a gas or liquid is volatilized in the molten resin to generate bubbles in the resin, and as a result, the resin is foamed.

The main blowing agents which can be used in the present invention are aliphatic hydrocarbons, alicyclic hydrocarbons, halogenated aliphatic hydrocarbons, carbon dioxide and nitrogen. As the aliphatic hydrocarbon, propane, normal butane, isobutane,
Normal pentane, isopentane, neopentane and the like can be used. As the alicyclic hydrocarbon, cyclopentane, cyclohexane and the like can be used.
As the halogenated aliphatic hydrocarbon, 1,1-difluoroethane, 1,1,1,2-tetrafluoroethane, methyl chloride and the like can be used. These can be used alone or as a mixture. Among these, preferred blowing agents are aliphatic hydrocarbons, alicyclic hydrocarbons,
Carbon dioxide.

According to the present invention, the cylindrical laminate extruded from the die is crushed while its inner surface is still softened. It is preferable to use a pair of pinch rolls for crushing. The inner surfaces of the crushed tubular laminate are fused together to form an inner layer, whereby a thick laminated sheet is obtained. The entire surface of this laminated sheet, including the sides,
It is covered with a resin foam positioned outside during lamination.

When the melt of the foamable resin is merged in the die, it is preferable to appropriately maintain the viscosity of the foamable melt. That is, if you are indifferent to the viscosity of the foamable melt, the melt will cause undesirable mixing at the time of merging,
This is because each layer does not have a uniform thickness, or in extreme cases, an inner layer appears on the surface. When the viscosity of the foam is adjusted so that the viscosity of the foamable melt that comes to the outside of the laminate is 1.1 times or less the viscosity of the foamable melt that comes to the inside of the laminate and then joined, Such undesirable mixing does not occur.

[0023]

According to the method of the present invention, a cylindrical gap is provided.
Using a die that Tsu, this included a blowing agent causes melt respectively the composition of different styrene resin compositions in separate extruder, and then the respective resin separately above 1
One of putting the mouthpiece formed into a circular columnar or circular tubular to a common axis and then are merged in the same die with a circular cylindrical laminate of a plurality of layers made of foamed resin, extruded from a die in the form since foaming, a circular cylindrical laminate comprising a plurality of layers that foaming can not peel low expansion ratio in the boundary layer, also boundary layers are firmly fused, thus entirely uniform foam Thus, a strong foam laminate is obtained. Since the obtained foam is uniformly foamed as a whole, it can be easily processed into a molded product. In addition, while the inner surface of the expanded tubular laminate is still softened, the tubular laminate is crushed to fuse the inner surfaces together, so that the resulting foam has a thicker inner surface that is firmly fused. It becomes a foam sheet. Generally, it is difficult to produce a thick foamed sheet, but according to this method, it is easy to produce. In particular, it is a very efficient production method as compared with a lamination method by thermal bonding between foamed sheets as described in WO 92/08610.

Since this foamed sheet is covered with a resin foam arranged so that the whole surface comes to the outside at the time of lamination, a foamed sheet with a beautiful appearance can be obtained simply by selecting a new material as the resin coming out. Obtainable. In other words,
Since the foam inside does not appear on the outer surface at all, a styrene-based resin foam sheet having a beautiful appearance can be obtained by using a recovered product or a low-quality styrene-based resin inside. Therefore, the method of the present invention is also valuable as a method of using a recovered product or a low-quality styrene resin foam. Further, when a large amount of the foaming agent is mixed in the inside, the fusion property of the inner surface is improved. Further, when a high-density foam layer is formed on the outside, a multilayer structure having excellent bending strength is obtained. Thus, a multilayer structure having various characteristics can be produced. The method of the invention
It gives such benefits.

[0025]

The method of the present invention will be specifically described below with reference to examples and comparative examples. In the following, simply “parts” means parts by weight.

[0026]

Example 1 As an extruder 1, an extruder having a diameter of 115 mm was used. A mixture of 100 parts of miscellaneous color recovered polystyrene and 0.4 part of talc was supplied thereto, and a mixture of 65% normal butane and 35% isobutane was used as a foaming agent, at a ratio of 4.0 parts to 100 parts of the resin. Press into the extruder midway, knead well, then cool.
The temperature was adjusted to 80 ° C.

As the extruder 2, an extruder having a diameter of 90 mm was used. A mixture of polystyrene (MI = 2.8, Stylon QG-683) and 1.0 part of talc was supplied thereto. As a blowing agent, a mixture consisting of 30 parts of normal butane and 70 parts of isobutane was added to 3.5 parts of 100 parts of the resin. At the same time, press in the extruder midway, mix well, then cool,
The temperature was adjusted to 170 ° C. at the extruder outlet.

The above two are fed to the merger adapter 21 from the extruder 1 at 150 kg / hr and from the extruder 2 at 75 kg / hr.
hr, they are introduced into the inlets 32 and 31, respectively, merge at the outlet of the adapter, enter the mouthpiece and collide with torpedo,
200m inside diameter of the outlet of the base
After being extruded as a two-layer laminate from an orifice with a m gap of 1.2 mm, air is blown from an earring 222 onto the surface layer, the tube is crushed by a pinch roll 41 via a guide roll, and cut while being pulled by a take-off machine. 5.5mm in width, 800mm in width, total basis weight 400gr / c
An m ² plate-like foam was obtained. The center recovered polystyrene foam layer was 3.8 mm, and the front and back white polystyrene foam layers were 0.85 mm each.

[0029]

Example 2 As the extruder 1, an extruder having a diameter of 115 mm was used. A mixture of 100 parts of miscellaneous color recovered polystyrene and 0.3 part of talc is supplied thereto, and a mixture of 65% normal butane and 35% isobutane is used as a foaming agent, and is extruded at a ratio of 4.0 parts to 100 parts of the resin. Press in from the middle of the machine, knead well, cool, and
The temperature was adjusted to 5 ° C.

As the extruder 2, an extruder having a diameter of 90 mm was used. To this, a GP polystyrene resin (Denka GP-
1 MI = 6.9) 80 parts and high impact polystyrene resin (Denka HIS-2 MI = 7.2) 20 parts A mixture of 1.0 part of talc and 0.08 part of calcium stearate is supplied. Normal butane 30
And a mixture of 70 parts of isobutane were injected into the extruder at a rate of 3.2 parts per 100 parts of the resin, kneaded well, cooled, and adjusted to 175 ° C. at the outlet of the extruder.

The above two are combined by the merging adapter 21 to 150 kg / hr from the extruder 1 and to 60 kg / hr from the extruder 2.
/ Hr into the inlets 32 and 31, respectively, merge at the adapter outlet, enter the base and collide with torpedo,
It has a cylindrical shape with two layers combined and has an inner diameter of 200
After being extruded from the orifice having a gap of 1 mm as a two-layer laminate, air is blown from the earring 222 onto the surface layer, the tube is crushed from the pinch roll 41 through the guide roll, and cut while being taken off by the take-off machine. .1mm, width 800mm, total basis weight 280gr / c
An m ² plate-like foam was obtained. The central recovered polystyrene foam layer was 2.6 mm, and the front and back white polystyrene foam layers were 0.25 mm each.

[0032]

Example 3 As an extruder 1, an extruder having a diameter of 115 mm was used. A mixture of 100 parts of miscellaneous color recovered polystyrene and 0.4 part of talc was supplied thereto, and a mixture of 65% normal butane and 35% isobutane was used as a foaming agent, at a ratio of 4.0 parts to 100 parts of the resin. Press into the extruder midway, knead well, then cool.
The temperature was adjusted to 80 ° C.

As the extruder 2, an extruder having a diameter of 90 mm was used. A mixture of polystyrene (MI = 1.8, Stylon QG 693), 1.0 part of talc and 0.08 part of calcium stearate was supplied, and a mixture of 30 parts of normal butane and 70 parts of isobutane was used as a foaming agent. The mixture was press-fitted in the middle of the extruder at a rate of 4.0 parts per 100 parts, kneaded well, cooled, and cooled at the outlet of the extruder.
The temperature was adjusted to 60 ° C.

The above two are fed to the merger adapter 21 from the extruder 1 at 150 kg / hr and from the extruder 2 at 75 kg / hr.
hr, they are introduced into the inlets 32 and 31, respectively, merge at the outlet of the adapter, enter the mouthpiece and collide with torpedo,
200m inside diameter of the outlet of the base
After being extruded from the orifice with a gap of 1.8 mm as a two-layer laminate, air is blown from the earring 23 to the surface layer, the tube is crushed by the pinch roll 41 via the guide roll, and cut while being pulled by the take-off machine. 8.5mm in width, 800mm in width, total basis weight 500gr / c
An m ² plate-like foam was obtained. The central recovered polystyrene foam layer was 5.5 mm, and the front and back white polystyrene foam layers were 1.50 mm each.

[Brief description of the drawings]

FIG. 1 is a schematic partially cutaway sectional view of an apparatus suitable for carrying out the method of the present invention.

FIG. 2 is a cross-sectional view of a foamable melt molded at a line AA 'in FIG.

FIG. 3 is a cross-sectional view of a foamable melt molded at a line BB ′ in FIG. 1;

FIG. 4 is a cross-sectional view of the foam laminated sheet formed at the line CC ′ in FIG.

[Explanation of symbols]

 1, 2 Extruder 21 Converging part of die 22 Tip part of die 221 Torpedo

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 47/00-47/94

Claims (2)

(57) [Claims] [Claim 1] using a die having a cylindrical gap, different this contained a foaming agent to the styrene-based resin in a separate extruder together with melting respectively, then separately the one of the base of each resin compositions To make the axis common
Formed into a circular columnar or circular tubular, then they are merged in the same die with a circular cylindrical laminate of a plurality of layers made of a foamable resin, foamed extruded from a nozzle in this form, the foamed tubular laminate A method for producing a foamed laminated sheet of a styrene resin, characterized in that a cylindrical laminated body is crushed while the inner surface is still softened to fuse the inner surfaces together to form a laminated foamed sheet. 2. A composition having a composition having a cylindrical gap.
Melt different styrene resins in separate extruders
And add a foaming agent to it.
The resin separately into the above one base to make the axis common
Form into a column or cylinder, then join in the same base
To form a columnar molded body, then the center of the cylindrical molded body
Multilayer cylindrical laminate made of foamable resin with perforations
And then extruded from the base in this form and foamed, foamed
While the inner surface of the cylindrical laminate is still softened,
And squeeze the inner surfaces together to form a laminated foam sheet.
Styrene resin foam laminated sheet characterized by the following:
Manufacturing method.