JPS599337B2 - Method for manufacturing composite deformed foam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composite irregularly shaped foam, and more particularly, to a method for manufacturing a foam with a irregularly shaped structure having a complex cross-sectional shape, in which the inner layer is made of a foamed resin and the surface layer is made of a non-foamed resin. It is something.

Conventionally, methods for manufacturing this type of composite irregularly shaped foam are disclosed in Japanese Patent Publication No. 40-954, Japanese Patent Publication No. 46-19952,
Japanese Patent Publication No. 47-47103, Japanese Patent Publication No. 47-4296
Publication No. 1, Japanese Patent Publication No. 1986-86969, Japanese Patent Application Publication No. 1973
-9573 publication, JP-A-50-107067 publication,
JP-A-50-108366, DP1183238
It can be found here and there in the specification of No. 1, DOS No. 1913921, etc.

These conventional methods rarely cause problems when producing composite irregularly shaped foams having a relatively simple structure, ie, molded articles having a circular or rectangular cross-sectional shape, for example. However, when trying to obtain a molded product with a somewhat complex irregular cross section, for example, the thickness of the non-foamed resin that becomes the outer layer may not be uniform, or foaming gas may accumulate at the interface between the non-foamed resin and the foamed resin, resulting in the molded product This caused problems such as a decrease in the strength of the steel. For this reason, conventional methods try to solve this problem by, for example, suctioning and removing the excess gas generated at the interface between non-foamed resin and foamed resin, or using a blowing agent with a specific decomposition temperature range. However, it is still not completely satisfactory.

The present inventors solved the drawbacks of such conventional methods, and developed a method in which the foamed resin of the inner layer and the non-foamed resin of the surface layer are firmly bonded, and also have a complex irregular cross-sectional shape. However, as a result of various studies aimed at developing a manufacturing technology that can produce composite irregularly shaped foams with a uniform thickness of non-expandable resin on the surface layer, we have developed a method that combines a unique extrusion method and a secondary shaping method. The inventors have discovered that the above object can be achieved by doing so, and have completed the present invention.

In other words, the gist of the present invention is that when manufacturing a composite irregularly shaped foam body in which the inner layer is made of a foamed resin and the surface layer is made of a foamed resin, the non-foamed resin that will be the surface layer and the foamed resin that will be the inner layer are mixed inside a die. The two resins are merged so that the cross-sectional shape becomes circular or annular, and the combined resins have a cross-sectional area of 2/3 to 1/10 of the flow path cross-sectional area at the merging point of the two resins, In addition, the cross-sectional shape whose temperature is 3 to 30 °C lower than the die temperature at the confluence point is extruded from a circular or annular opening, and both resins are still in a softened state after foaming and expanding or while foaming and expanding. The present invention relates to a method for producing a composite irregularly shaped foam, which is characterized by secondary shaping.

The method of the present invention will be explained in detail below.

Types of resins that can be used to carry out the method of the present invention and form the inner layer and surface layer of the product include styrene resins such as polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene ternary copolymer; polyacrylic acid , acrylic resins such as polyacrylic ester, polymethacrylic acid, polymethacrylic ester;
Vinyl chloride resins such as polyvinyl chloride, vinyl chloride monoacetate vinyl copolymer, olefin resins such as polyethylene, polypropylene, ethylene-propylene copolymer, polybutene-1, ethylene monoacetate copolymer; nylon 6. Polyamide resins such as nylon 6-6 and nylon 6-10; thermoplastic synthetic resins such as polyester resins such as polyethylene terephthalate and polybutylene terephthalate; if they can be molded by extrusion molding, , any resin may be used.

In addition, the foamed resin that forms the inner layer and the non-foamed resin that forms the surface layer are preferably the same resin or resins that are mutually fusion-adhesive (compatible) in order to ensure good bonding between the inner layer and the surface layer.
In some cases, it may be a combination of three resins that are not compatible.

In addition, additives such as antioxidants, ultraviolet absorbers, heat stabilizers, antistatic agents, flame retardants, dyes, pigments, organic fillers, and inorganic fillers may be added to these resins to avoid any hindrance in carrying out the method of the present invention. It goes without saying that the three additives may be mixed and used within a range that does not result in the following effects.

In addition, as blowing agents for foaming the resin forming the inner layer, chemical blowing agents such as azodicarbonamide, N-N'-dinitrosopentamethylenetetramine, P-toluenesulfonyl hydrazide, sodium bicarbonate, ψ ammonium carbonate, etc. Any foaming agent commonly used as a blowing agent for synthetic resins may be used, such as low-boiling hydrocarbons such as , butane, pentane, and hexane.

By the way, chemical blowing agents that are usually solid at room temperature are added to the resin before the resin is introduced into the extruder and mixed in a mixer. While the resin is being introduced into the extruder and being kneaded, it is forcibly forced into the cylinder of the extruder using a plunger pump or the like.

Of course, it is also possible to use both chemical blowing agents or a chemical blowing agent and a low boiling point hydrocarbon. Hereinafter, an example of the method of the present invention will be explained with reference to the drawings, but the method of the present invention is not limited to the following example unless it exceeds the gist thereof. 1st
The figure is a partially cutaway side view showing a specific example of the apparatus used in carrying out the method of the present invention, and FIG. 2 is an A-A in FIG.
FIG. 3 is a cross-sectional view of the BB portion, FIG. 4 is a cross-sectional view of an example of a product obtained by the method of the present invention, taken in a plane perpendicular to the extrusion direction, and FIG. FIG. 3 is a partially cutaway sectional view showing an example of another device used in carrying out the method of the present invention.

In the figure, 1 is the die body, 2 is the surface resin inlet, 2
' is the resin for the surface layer, 3 is the inner layer resin inlet, 3'' is the inner layer resin flow path, 4 is the composite resin, 5 is the confluence point, 6 is the resin flow path, 7 is the die opening, 8 is the sizing device, 9 is the Collection device, 10
11 indicates a composite foam, 11 indicates a core, and 12 indicates a spider.

The inner layer resin 3' (foamed resin) and the surface layer resin 2'' (non-foamed resin) melted and kneaded by an extruder (not shown) are respectively introduced into the die body 1 from the inner layer resin inlet 3 and the surface layer resin inlet 2. The two resins are introduced into the die body 1 and join together to form a composite resin 4.

At this time, the non-foamed resin introduced from the surface layer resin introduction [ ] 2 has a circular cross-sectional shape (the shape when cut parallel to the A-A cross section) until it reaches the confluence point 5. is,
Foamed resin 3 introduced into the interior from the inner layer resin introduction port 3
′ is filled in. The proportion of non-foamed resin and foamed resin at this confluence point 5 is preferably such that the non-foamed resin accounts for about 10 to 40% of the cross-sectional area when cut parallel to the A-A cross section. Surface layer resin 2 at confluence point 5
'' and the inner layer resin 3' refer to its cross section (a cross section parallel to the A-A cross section).

) is circular or annular in shape. This is to make the pressure distribution uniform and to make the surface layer resin 2' have a uniform thickness. The surface layer resin 2'' and the inner layer resin 3'' that have merged and become one in this way are extruded from the opening 7 through the resin flow path 6, but in this case, the cross-sectional area of the resin flow path 6 is (cross section when cut perpendicular to the extrusion direction) is gradually reduced, and the cross-sectional area of the opening is 2/3 to 1/10, preferably 1/2 of the flow path cross-sectional area at the confluence 5 of the resin flow path 6.
~1/5.

This increases the resin pressure within the die body 1, prevents the inner layer resin (foamed resin) from foaming within the die body 1, and prevents foaming gas from accumulating at the interface between the surface layer resin and the inner layer resin. This is to prevent it. When extruding so as to have an annular cross-sectional shape, a die having a core 11 and a spider 12 as shown in FIG. 5 may be used.

Further, the temperature of the die opening of the die body 1 needs to be set 3 to 30° C. lower than the die temperature at the confluence point.

This is because the foamed resin, whose foaming was suppressed by increasing the resin pressure inside the die body 1, is extruded from the die opening.
Foaming starts when the pressure is removed, but in this case, the higher the resin temperature, the better the foaming, and the higher the temperature of the resin, the more concentrated the resin will be. By cooling, the temperature gradient of the resin increases from the surface layer to the inside, and the foaming gas is concentrated in the center of the inner layer resin 3'', and the foaming gas is generated at the interface between the surface layer resin 7 and the inner layer resin 3''. This is to prevent it from accumulating. The cross-sectional shape of the opening 7 is also circular or annular in order to make the thickness of the surface layer resin 2'' uniform.

That is, of course, when merging in a circular or annular shape at the merging point 5 and extruding it into an irregular shape at the opening, but also when merging into an irregular shape at the merging point and extruding into an irregular shape at the opening. This is because the pressure distribution in the direction perpendicular to the flow of the resin is not uniform in the irregularly shaped part, causing a two-dimensional flow in the resin, and the thickness distribution of both resins becomes extremely uneven, which is undesirable. . In this way, the resin extruded from the opening 7 of the die body 1 with a circular or annular cross-sectional shape is transferred to the die body 1.
It foams and expands outside the cell, forming a circular or annular composite foam.

Next, this composite foam is secondarily shaped into a desired irregular shape using an appropriate sizing device 8.

This secondary shaping is performed while the composite foam made of both foamed resin and non-foamed resin extruded from the die body 1 is still in a softened state, and the composite foam is shaped into a desired irregular shape. Form into a cross-sectional shape. The sizing device used for this secondary shaping is, for example, one that shapes the composite foam by sandwiching it between uneven rolls, or the one proposed by the present inventors, A sizing device such as that disclosed in Japanese Patent Application Laid-open No. 49-34969 and Japanese Patent Application Laid-Open No. 49-38965 may be used. To briefly explain the sizing device disclosed in Japanese Unexamined Patent Publication No. 49-34969, etc.,
This sizing device has a cylindrical shape (
Box-shaped), in which a plurality of protrusions are provided on the part facing the die body, adjusting the perspective as appropriate depending on the amount of deformation of the object to be molded, that is, the composite foam extruded from the die body. It is.

This cylindrical sizing device preferably cools and fixes the molded product at the same time as shaping it, and is usually cooled. In addition, when using this cylindrical sizing device,
It is desirable to provide a take-off device 9 for forcibly taking over the composite deformed foam 10 from the front of the sizing device 8.

Of course, this pulling device may be of any type, such as a roller or an endless belt. Furthermore, when shaping a hollow composite irregularly shaped foam, the shaping can be carried out satisfactorily by using the sizing device 8 provided with vacuum holes on the inner surface.

The composite irregularly shaped foam 10 thus obtained is cut into appropriate lengths to produce a product.

From the viewpoint of strength, moldability, etc., the foaming ratio of the product is preferably 2 to 4 times the apparent foaming ratio including the surface layer.

Hereinafter, a specific example of the method of the present invention will be explained using Examples.

EXAMPLE A composite irregularly shaped foam was manufactured using an apparatus as shown in FIG.

The foamed resin is 100 parts by weight of high-impact polystyrene manufactured and sold by Mitsubishi Monsanto Chemical Co., Ltd. under the registered trademark Dialex HT59, 0.4 parts by weight of azodicarbonamide as a blowing agent, and 0.4 parts by weight of sodium bicarbonate. 4 parts by weight, 0.4 parts by weight of zinc oxide as a foaming aid,
0.2 parts by weight of dioctyl phthalate was added and mixed as a spreading agent.

As the non-foamed resin, impact-resistant polystyrene manufactured and sold by Mitsubishi Monsanto Chemical Co., Ltd. under the registered trademark Dialex HT48 was used. As an extruder for foamed resin, screw diameter: 401t1Lφ, L
/D (screw length/screw diameter): 22, compression ratio: 2.5 extruder is used for non-foamed resin, screw diameter: 25 mmφ, L/D: 16, compression ratio 3.0. A machine was used.

The set temperature of the extruder and die is 145°C at the rear of the cylinder (one side of the hopper) and 160°C at the middle of the extruder for foamed resin.
, 175℃ for the front part (die side) and 160℃ for the connection part with the die.
℃, and the extruder for non-foamed resin has the rear part of the cylinder at 170℃.
°C, and the front part was 200 °C.

The temperature of the die is 145℃ at the confluence point and 135℃ at the die opening.
And so. The die had a total cross-sectional area of the confluence point of 4.5 d, of which the area of the surface layer resin was 20%, and the cross-sectional area of the opening was 1.2 d.

Molding was carried out under these settings, and the resin pressure was adjusted to 80K at the confluence point of the die! ? /Cr! I did this so that i.

The round rod-shaped composite foam extruded from the die was shaped and cooled using a sizing device as shown in FIG. 1, and then taken out to obtain a composite irregularly shaped foam as shown in FIG. 4.

Its cross-sectional area was 2.2 cd, and its apparent density was 0.55 r/~. In addition, the thickness of the non-foamed resin on the surface layer is 0.7 to 0.
．． 911 and was extremely uniform. Comparative Example The temperature and pressure conditions were the same as in Example 1, except that the shape of the die opening was the same as the cross-sectional shape of the molded product shown in Figure 4, and the cross-sectional area was 1.2CF71. The molding process was carried out.

The obtained molded product has an apparent density of 0.58? /(7!i), and the thickness of the non-foamed resin in the surface layer was significantly non-uniform, ranging from 0.1 to 2.011 m.

As described above, according to the method of the present invention, the foamed resin and the non-foamed resin are combined in the die in a circular or annular shape with a uniform pressure distribution of the resin pressure, and the resin is extruded from the die while maintaining that shape. Since a composite foam with an irregular cross section is created by secondary shaping outside the die, the internal thickness distribution of the surface layer only produces wall thickness deviation due to secondary shaping, resulting in an extremely uniform wall thickness. Molded products can be obtained and are suitable for use as various building materials.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway side view showing a specific example of the apparatus used in carrying out the method of the present invention, and FIG.
A cross-sectional view of part A, FIG. 3 is a cross-sectional view of part B-B,
Fig. 4 is a cross-sectional view perpendicular to the extrusion direction of an example of a product obtained by the method of the present invention, and Fig. 5 is a partially cutaway view showing an example of another device used in carrying out the method of the present invention. FIG.

Claims (1)

[Claims] 1. When manufacturing a composite irregularly shaped foam whose inner layer is a foamed resin and the surface is a non-foamed resin, the non-foamed resin that will be the surface layer and the foamed resin that will be the inner layer are molded into a circular or annular cross-sectional shape inside a die. After that, the two resins are merged into a single body, and then the two resins are combined into one resin, and the cross-sectional area of the flow path at the merging point of the two resins is 2/3.
The cross-sectional shape, which has a cross-sectional area of ~1/10 and whose temperature is 3 to 30 degrees Celsius lower than the die temperature at the confluence point, is extruded through a circular or annular opening, and after foaming and expanding, or foaming and expanding. A method for producing a composite irregularly shaped foam, characterized in that the resins are secondarily shaped while both resins are still in a softened state.