JPS5829328B2 - Method for producing polyester extruded foam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an extruded polyester foam, and an object thereof is to provide a method for producing an extruded polyester foam having a uniform cell structure and a high expansion ratio.

Traditionally, aromatic polyesters, especially polyethylene terephthalate and polybutylene terephthalate, have been used for fibers, films, injection molded products, etc. due to their excellent mechanical properties, heat resistance, chemical resistance, and dimensional stability. There is.

However, aromatic polyester has a low melt viscosity, and when trying to produce a foam molded product by extrusion molding, it is difficult to make the bubbles uniform in size and distribution, and sometimes gas separates from the molten resin and falls out. It was difficult to obtain a good foam molded product.

In order to improve these drawbacks, polyester with a high degree of polymerization conventionally produced by solid phase polymerization or addition of a polymerization accelerator, or polyester whose melt viscosity has been increased by copolymerizing a branching agent, is used as the raw material. It is proposed that.

However, with these methods, it has been difficult to stably obtain a polymer having a melt viscosity sufficient for the purpose of obtaining a uniform, finely foamed product at a low cost.

In recent years, as a manufacturing method for polyester extruded foam products that improves these drawbacks, aromatic polyesters are added with a specific proportion of a jepoxy compound and a group 1a metal of the periodic table, a metal of group 1a of the periodic table.
A method has been proposed in which a composition containing one or more substances selected from the group consisting of group metals and their compounds is extruded and foamed (see JP-A-53-24364).

According to this method, it is possible to produce a highly foamed product, but the diameter of the die hole is limited and it is difficult to obtain a large foamed product.

For example, when producing a foam with a diameter about four times the die hole diameter, the above method is possible, but it is difficult to produce a highly foamed foam with a diameter larger than this. , only low foam or foam with non-uniform cell distribution can be obtained.

As a result of intensive research in order to solve such restrictive conditions, the present inventors made the polyester pre-foam extruded from the die further pass through a vacuum zone to expand it, and at the same time, The inventors have discovered that by cooling and solidifying the foam, it is possible to easily and stably obtain a foam with increased humidity and a high degree of foaming, and have thus arrived at the present invention.

That is, in the present invention, when aromatic polyester is melted and extruded and foam-molded, a jepoxy compound of A O, 05 to 5 by weight and Bo, 05 to 3 by weight of a jepoxy compound, and Bo, 05 to 3 by weight, are added to the aromatic polyester. one or more substances selected from the group consisting of metals of the main group and their compounds, and further C0,0
A method for producing extruded polyester foam, which comprises pressurizing 5 to 50 parts by weight of a "substance with a boiling point of 200°C or less at normal pressure" and extruding it into foam, followed by further expansion under reduced pressure and solidification by cooling. It is.

Hereinafter, the present invention will be explained using the drawings.

FIG. 2 shows an example of a manufacturing apparatus used in carrying out the manufacturing method of the present invention, and shows a state in which an extruder and a sizing apparatus are connected.

In Fig. 2, 1 is an extruder, 2 is a screw installed in the extruder 1, 3 is a die, 4 is a connecting cap, 5 and 11 are cooling water vents, 6 is a sizing cap, and 7 is a vacuum. 8 is a cooling water flow path of the cooling jacket, 9 is a vacuum suction hole, 10 is a foam, 12 is a sealing cap, 13
14 is the gasket in the sealing cap 12, and the foam 1
0 is a take-up machine, and 15 is a main body of a sizing device.

The extruder 1 may be one conventionally used as a foam molding machine, and melts aromatic polyester and presses an evaporative foaming agent or other foaming agent into the melted resin at or before and after the center of the extruder, It has a function of mixing and extruding the obtained "melt plasticized foamable aromatic polyester composition" from a die.

Further, the sizing device 15 has a sizing tube in which sizing mouthpieces 6 are installed at arbitrary intervals and vacuum suction holes 9 are provided at arbitrary positions (having a decompression zone). A cooling jacket having cooling water flow passages 8 is provided.

The cooling water passage 8 communicates with the cooling water vents 5 and 11, and for example, the cooling water supplied from the cooling water vent 5 passes through the cooling water passage 8 and is drained from the cooling water vent 11. .

The sizing caps 6 provided at arbitrary intervals in the sizing cylinder are expanded by expanding the foam 10 in a part of the circumference of the sizing caps 6.
A vacuum hole 7 may be provided to maintain the balance of the degree of vacuum even after contacting the inner surface of the substrate.

The shape of the east sizing 1 metal 6 can be changed depending on the desired cross-sectional shape of the foam.

The location where the vacuum suction hole 9 is bored in the sizing tube is arbitrary, and it is preferable to select a location where the effect can be fully exhibited.

Furthermore, if a change in the degree of vacuum is required within the sizing cylinder, the sizing cylinder may be divided into two or more sections, and the vacuum suction holes 9 may be provided in each section.

The material of the gasket 13 inside the sealing cap 12 is one that allows the foam 10 to further expand in accordance with the degree of vacuum within the sizing cylinder and facilitate passage of the foam even if the foam changes shape. is preferable, for example, soft resin, rubber (
(natural, synthetic, or composite rubber, etc.).

In FIG. 2, the aromatic polyester extruded from the die 3 passes through the connecting cap 4, is sucked through the vacuum suction hole 9, foams and expands in the sizing cylinder maintained at a predetermined degree of vacuum, and is then cooled. After that, the foam is continuously indexed as a foam through a sealing cap 12 by a take-off machine 14.

The extruder 1 and the sizing device 15 are normally connected using fasteners such as bolts after the foam extruded from the die 3 is continuously indexed to the take-up device 14.

As is clear from the above description, the main body of the sizing device has horizontal movability.

Preferred aromatic polyesters used in the present invention include polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate, polyethylene-2,6-naphthalate, and copolyesters containing these as main components.

Such aromatic polyesters may be used alone, but
Moreover, two or more types may be mixed and used.

In the present invention, jepoxy compounds used as component A include polyalkylene glycol jepoxy compounds (for example, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, polytetramethylene glycol diglycidyl ether, etc.), bisphenol jepoxy compounds ( For example, diglycidyl ether of 2,2-bis(4-hydroxyphenyl)propane, diglycidyl ether of the following formula obtained by reacting 2,2-bis(4-hydroxyphenyl)propane and epichlorohydrin in various proportions. ether [However, n is a number from 0 to 10.

), jepoxy compounds of polyhydric alcohols (e.g. ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tetramethylene glycol diglycidyl ether, glycerol diglycidyl ether, neopentyl glycol diglycidyl ether, etc.),
Examples include diglycidyl phthalate, dicyclopentadiene diepoxide, 3,4-epoxy-6-methylcyclohexanecarboxylate, 3,4-epoxycyclohexylmethyl, 3,4-epoxycyclohexanecarboxylate, and vinylcyclohexene diepoxide.

The ratio of the jepoxy compound used is preferably 0.05 to 5 weight more than the polyester.

If the amount of the jepoxy compound is more than 5 weight φ, gelation will occur violently, making it difficult to suppress the foaming pressure and obtaining a foam, and even if a foam molded product is obtained, the mechanical strength will decrease or coloration will be noticeable. This is not desirable as it may result in

A more preferable ratio of the jepoxy compound used is 0.1 to 4% by weight based on the polyester.

In addition, metals of main groups 1 to 1 of the periodic table and compounds thereof used as component B in the present invention include metals such as lithium, sodium, potassium, magnesium, calcium, and strontium, organic acid salts of these metals, Inorganic acid salts, alcoholades, phenolates, halides,
Examples include hydrides and oxides.

Specific examples of these compounds include lithium acetate, sodium acetate, potassium acetate, magnesium acetate, calcium propionate, magnesium butyrate, sodium caprylate, sodium caprate, magnesium laurate, calcium stearate, calcium myristate, calcium benzoate, Examples include potassium terephthalate, potassium carbonate, potassium bicarbonate, sodium phenoxide, calcium oxide, sodium oxide, magnesium oxide, montan wax salt, montan wax ester salt, and the like.

The amount of metals of main groups 1 to 1 of the periodic table and/or their compounds used is preferably 0.05 to 3 parts by weight, more preferably 0.1 to 2 parts by weight, based on the polyester. It is preferable.

The substance (foaming agent) used as component C in the present invention is:
"A substance with a boiling point of 200°C or less at normal pressure."

The substance must be one that does not have an adverse effect on the quality of the aromatic polyester during melt molding (
That is, it goes without saying that the material should be selected from among those that are inert to aromatic polyesters.

Component C is more preferably one having a boiling point of 150°C or less at normal pressure.

Preferred blowing agents include inert gases such as carbon dioxide, nitrogen, helium, xenon, and neon, and the following organic compounds having a boiling point of 200°C or less at normal pressure, such as (1) saturated aliphatic hydrocarbons, (2) Examples include saturated alicyclic hydrocarbons, (1) halogenated saturated hydrocarbons, (2) ethers, and (2) ketones.

Particularly preferably used organic compounds include carbon atoms of 8
The following hydrocarbons (e.g. aliphatic saturated hydrocarbons such as methane, ethane, butane, hexane etc., alicyclic saturated hydrocarbons such as cyclohexane, ethylcyclopentane etc., aromatic hydrocarbons such as benzene, xylene etc.) Chlorinated saturated hydrocarbons having 2 or less carbon atoms (e.g. methyl chloride, methylene chloride, chloroform, carbon tetrachloride, ethyl chloride, dichloroethane, dichloroethylene, etc.), fluorinated saturated hydrocarbons having 2 or less carbon atoms (e.g. carbon tetrafluoride, ethyl fluoride, ethane tetrafluoride, etc.), chlorinated fluorinated saturated hydrocarbons having 2 or less carbon atoms (e.g. chlorodifluoromethane, dichlorofluoromethane, chlorotrifluoromethane, dichlorodifluoromethane, trichlorofluoride) methane, dichlorotetrafluoroethane, trichlorotrifluethane, tetrachlorodifluoroethane, etc.), fluorobenzene, chlorobenzene, ethers having 6 or less carbon atoms (preferably diethers, such as methylal, acetal, 1,4-dioxane, etc.) ), ketones having 4 or less carbon atoms (eg, acetone, ethyl methyl ketone, acetylacetone, etc.).

The blowing agents may be used alone or in combination of two or more.

The addition ratio of the blowing agent is 0.0% to the aromatic polyester.
It is preferable that the weight is 0.05 to 50.

In the present invention, a melt-plasticized foamable aromatic polyester composition is extruded through a hole in a die 3 into a normal pressure section using a screw 2 under high pressure, and the pre-foamed product is vacuum sized using a guide support rod. The foam is introduced into the device and indexed by a puller 14.

After that, the die 3 and the cap 4 are connected.

The embodiment shown in FIG. 2 also shows this state.

When the foam 10 that has been continuously pulled up by the pulling machine 14 has a predetermined shape, the degree of vacuum in the vacuum cylinder is gradually increased by the vacuum pump.

At this time, as shown in FIG. 1, the expansion ratio of the foam 10 increases as the degree of vacuum increases, and the shape increases in proportion to the degree of vacuum.

Note that a feature of the present invention is that any foam can be formed by appropriately adjusting the degree of vacuum.

Moreover, as for the shape, by simply changing the sizing mouthpiece 6 and the sealing mouthpiece 12, it can be applied not only to rods but also to extruded foams such as sheets, pipes, and irregularly shaped products.

The aromatic polyester foam obtained by the present invention is
In contrast to the conventional normal pressure method, for example, the diameter is 1.
The effect of increasing the foaming ratio by more than 5 times was observed, and the foaming ratio was ranked first.
As shown in the figure, the effect was increased from <11 times to more than 30 times.

Moreover, it is possible to obtain a foam in which air bubbles are uniformly dispersed.

Hereinafter, the present invention will be explained in further detail with reference to Examples.

Example 1 After drying 100 parts by weight of polyethylene terephthalate pellets with an intrinsic viscosity of 0.64 at 130°C for 8 hours with hot air,
The pellets were uniformly sprinkled with 1 part by weight of diglycidyl ether of bisphenol A, 0.3 parts by weight of sodium montanate, and 0.5 parts by weight of talc using a ■-type blender, and then passed through a tandem-type extruder consisting of a cylinder diameter of 40 and 5 OrIm. Using this, a direct air sizing device having an inner diameter of 70 mm and a length of 5 m was connected to the tip of a die having a hole diameter of 5 wrL, and foam molding was performed.

In foam molding, 7 parts by weight of carbon dioxide gas is pumped into the center of the cylinder of the first extruder at 45 kg/cr! I pressed it in.

The extrusion conditions were such that the cylinder temperature of the first extruder was in the range of 270°C to 280°C, and the cylinder temperature of the second extruder was in the range of 270°C to 280°C.
The temperature was set in the range of 60°C to 270°C, and the screw rotation speed was 30rllD in the first extruder.

The second extruder has a speed of 23 rpm and a discharge pressure of 70 Kf/c.
It was set as 4.

The foam extruded under these conditions was continuously passed through a sizing cylinder with a degree of vacuum of 400 mHP while being gradually cooled at a rate of 3 m per minute to form foam.

The obtained foam had a diameter of 35 mm, and almost no change was observed due to shrinkage at a foaming ratio of 22 times.

A foam with a beautiful appearance and homogeneous cells was obtained.

The results are shown in Table 1. Example 2 Using the same raw material composition and extrusion conditions as in Example 1,
The product extruded and foamed under these conditions is vacuumed at 650mmHS.
Foam molding was carried out by passing the material continuously through the inside of the sizing cylinder at a rate of 4 m per minute while gradually cooling it.

The resulting foam had a diameter of 45 m and a foaming ratio of 3.
Almost no change in contraction of 2 times is observed.

A foam with a beautiful appearance and homogeneous cells was obtained.

The results are shown in Table 1. Comparative Example 1 A raw material composition and extrusion conditions similar to those of Example 1 were extruded into the atmosphere and foam-molded without using a vacuum sizing device.

The obtained foam contracted during the cooling and solidification process, and the foam had a diameter of 18, a foaming ratio of 11, and an oval shape with a poorly assembled appearance.

The results are shown in Table 1.

In addition, when the raw material composition and extrusion conditions are the same as above, and a die with a hole diameter of 2 tran is used without using a vacuum sizing device, the diameter is 10-12 m and the expansion ratio is 18-18.
It was possible to obtain a foam with a relatively better appearance 23 times.

As is clear from the above Examples and Comparative Examples, in the present invention, even if an extrusion device of the same capacity is used, foaming which has a larger size, a beautiful appearance, and a considerably higher foaming rate than that obtained by ordinary foaming method. You get a body.

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating the relationship between the degree of direct air sizing in the direct air sizing device and the foaming ratio. FIG. 2 is a side sectional view of a vacuum sizing apparatus for producing foam, which is an example of an apparatus for carrying out the present invention.

Claims (1)

[Claims] 1. When melting and extrusion foaming aromatic polyester, Ao, 05-5 weight of a jepoxy compound and Bo, 05-3 weight of a jepoxy compound of main groups 1 to 1 of the periodic table are added to the aromatic polyester. one or more substances selected from the group consisting of metals and their compounds, and further CO,
A method for producing an extruded polyester foam, which comprises pressurizing 05 to 50% by weight of a "substance with a melting point of 200°C or less at normal pressure" and extruding it into foam, then further expanding it under reduced pressure, and solidifying it by cooling. .