JPS6148411B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a string-like aromatic polyester foam continuum, and its purpose is to provide a method for producing a string-like aromatic polyester foam having high heat resistance. As for foam, manufacturing methods using various plastic materials are being researched, and string-like products for use as cushioning materials are also industrially produced from expanded polystyrene and expanded polyethylene. On the other hand, foams made from polyester are expected to have excellent properties in terms of strength and heat resistance, and there has been a desire to develop a method for producing them. As a method for manufacturing this polyester foam, a liquid mixture of polyester and a large amount of a low-boiling solvent and a blowing agent is extruded under low pressure and low temperature.
The solvent is evaporated adiabatically, and the polyether is precipitated.
Japanese Patent Publication No. 43-3993 describes a method for producing a fibrous foam under such conditions that the film-like polymer wall of each cell exhibits a uniplanar orientation.
It is proposed by the publication No. The polyester fibrous foam produced by the above method is
Due to its high magnification and orientation, it has features such as high strength relative to its specific gravity. However, due to the nature of the method, which uses a large amount of solvent or blowing agent,
It is difficult to obtain a product with a medium density of about 0.05 to 0.5, and there are drawbacks such as insufficient rigidity depending on the application. In addition, as a method for manufacturing large polyester foams, a method has been proposed in which aromatic polyester is blended with a combination of a diepoxy compound and an alkali (earth) metal compound, and then a blowing agent is injected and the mixture is melt-extruded and foamed. (Refer to JP-A-53-24364, JP-A-54-50568, JP-A-54-70364, etc.). However, even if attempts are made to obtain string-like aromatic polyester by applying this method, the heat resistance of the obtained products will vary depending on the thickness of the string, the composition of the polyester, the cooling method, etc., and the desired effect will not be achieved. The problem is that it cannot be done. The inventor of the present invention has arrived at the present invention as a result of intensive studies to overcome this problem. That is, the present invention provides an aromatic polyester melt containing 1 to 50% by weight of a substance with a boiling point of 90°C or less at normal pressure and having a foaming ability with a viscosity of 8000 poise or more at a temperature 15°C higher than the melting point. A string-like aromatic compound having a cross-sectional area of 1 mm ² to 200 mm ² characterized by being treated to have a crystallinity of 30% or more of the crystallinity reached at the temperature showing the maximum crystallization rate after extrusion from a die. This is a method for producing polyester foam continuum. The aromatic polyester used in the present invention mainly contains aromatic dicarboxylic acids (85 mol% of dicarboxylic acids).
Polyester containing a dicarboxylic acid component (accounting for the above). Representative examples of the aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, and diphenoxyethane dicarboxylic acid. . The diol components preferably used in the polyester include ethylene glycol, trimethylene glycol, tetramethylene glycol, neopentylene glycol, hexamethylene glycol, cyclohexane dimethylol, tricyclodecane dimethylol,
Examples include 2,2-bis(4·β-hydroxyethoxyphenyl)propane, 4,4'-bis(β-hydroxyethoxy)diphenylsulfone, and diethylene glycol. The polyester includes
A small proportion of oxyacids such as p-oxybenzoic acid (15 mol% or less based on the dicarboxylic acid component), aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, etc. (15 mol% or less based on the dicarboxylic acid component) Alternatively, in a small proportion, a polyfunctional compound such as pentaerythritol, trimethylolpropane, trimellitic acid, pyromellitic acid, etc. or a monofunctional compound such as benzoic acid may be copolymerized. Aromatic polyesters particularly preferably used in the present invention include polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,
6-naphthalene dicarboxylate, or more than 50% of the repeating units are ethylene terephthalate, butylene terephthalate or ethylene-
Mention may be made of modified polyethylene terephthalate, modified polybutylene terephthalate or modified polyethylene-2,6-naphthalene dicarboxylate, consisting of 2,6-naphthalene dicarboxylate, with the remainder being other components. These modified polyesters in which other components account for 20% or less of the total repeating units are more preferably used. In the present invention, it is necessary that the viscosity of the melt at a temperature 15° C. higher than the melting point is 8000 poise or more. The reason for this is that when the melt is discharged from the die into atmospheric pressure, it is necessary for the individual cells of the bubbles to have adequate resistance to the foaming pressure to obtain a proper foam. Ru. In order to obtain a melt with such a melt viscosity,
The following three techniques are preferably applied. (1) Highly polymerized polyester produced by solid phase polymerization or addition of a polymerization accelerator is used. (2) Use polyester whose melt viscosity has been increased by copolymerizing a branching agent. Examples of branching agents include polyfunctional compounds such as pentaerythritol and glycerin. (3) Using a compound that increases the molecular weight of aromatic polyester or causes crosslinking,
Highly polymerized or crosslinked polyester is produced in an extruder. Examples of this compound include JP-A-53-
A combination of the diepoxy compound described in JP-A No. 24364 and a metal or compound of group a or a of the periodic table, or a combination of the diepoxy compound and montan wax salt or montan wax ester salt described in JP-A-54-50568. Examples include combinations of polyalkylene glycol diepoxy compounds described in JP-A-54-70364 and metals from groups 1 to 1 of the periodic table and their compounds. It is not limited. In order to give the aromatic polyester foaming ability, it is necessary to incorporate a gas inert to the aromatic polyester or a substance that is liquid at room temperature into the molten resin.
If a substance with a boiling point of over 90°C is used, it will tend to shrink when cooled to room temperature, so it is necessary to choose a substance with a boiling point of 90°C or lower. Examples of preferred substances include inert gases such as carbon dioxide, nitrogen, helium, xenon, and neon, and the following organic compounds with a boiling point of 90°C or less at normal pressure, such as saturated aliphatic hydrocarbons and saturated alicyclics. Examples include group hydrocarbons, halogenated saturated hydrocarbons, ethers, ketones, etc. Particularly preferably used organic compounds include hydrocarbons having 7 or less carbon atoms (for example, aliphatic saturated hydrocarbons such as methane, ethane, propane, butane, hexane, etc., and alicyclic saturated hydrocarbons such as cyclohexane, methylcyclopentane, etc.). ), chlorinated saturated hydrocarbons having 2 or more carbon atoms (e.g. methyl chloride, methylene chloride, chloroform,
Carbon tetrachloride, ethyl chloride, dichloroethane, dichloroethylene, etc.), fluorinated saturated hydrocarbons with 2 or less carbon atoms (e.g. carbon tetrafluoride, ethyl fluoride, ethane tetrafluoride, etc.), chlorinated carbon atoms with 2 or less carbon atoms Fluorinated hydrocarbons (e.g. chlordifluoromethane, dichlorofluoromethane, chlortrifluoromethane, dichlorodifluoromethane, trichlorofluoromethane, dichlorotetrafluoroethane, trichlorotrifluoroethane, tetrachlorodifluoro) ethyl ether, methylal, acetaldehyde dimethyl acetal, and ketones such as acetone and methyl ethyl ketone. These may be used alone or in combination of two or more. The proportion of an inert gas or a substance that is liquid at room temperature (hereinafter referred to as a blowing agent) added to provide foaming ability is 1 to 50% by weight based on the aromatic polyester. If the blowing agent is less than 1%, hardly any foaming will occur, making it impossible to obtain a practical foam molded product.If the blowing agent is more than 50% by weight, the blowing agent will not be uniformly incorporated into the molten resin, and gas will This is not preferable because it will blow out and make it difficult to obtain a foam of a predetermined shape. A more preferable addition range of the blowing agent is 2 to 40% by weight. As a method for adding a foaming agent to the molten resin, the following method can be used, for example. a Press fit through the vent provided in the middle of the cylinder of the extruder. b Press fit from two places, the vent part and the die part.c Press fit from two places at the die part. d) Press fit from three places in total: the vent part and the die part In the present invention, the extruded string-like foam is crystallized to a degree of crystallinity of 30% or more of the achieved crystallinity at the temperature showing the maximum crystallization rate. It is characterized by processing to achieve a high degree of naturalization. It has been found that by such treatment, it is possible to exhibit heat resistance while maintaining the rigidity specific to the expansion ratio in accordance with the temperature. In order to facilitate such processing, it is necessary to select an appropriate crystal nucleating agent, especially in the case of polyethylene terephthalate, which is known to have a slow crystallization rate. That is, by using sodium montanate, sodium salt of esterified ethylene glycol moiety of montanic acid, talc, graphite, kaolin, sodium benzoate, etc., the crystallinity reached at the temperature showing the maximum crystallization rate can be achieved. Heat treatment to obtain a crystallinity of 30% or more, preferably 50% or more can be facilitated. The heat treatment is preferably determined in consideration of the half-crystallization time at each temperature determined by the raw material polymer and additives, and the effective diameter of the string-like foam. As a guideline,

[Formula] (D: Effective diameter (cm) t1/2: Half-crystallization time (seconds)) ...Those with an effective diameter within the range shown in (1) will not meet the target no matter what cooling method is used. The crystallinity can be set to be 30% or more of the crystallinity reached at the temperature showing the maximum crystallization rate. On the other hand, if the effective diameter is smaller than the above formula, a covert cooling method must be chosen. The easiest method to implement is extrusion into the air. Further, for those with a small diameter, it is necessary to expose them to an atmosphere that promotes crystallization for a predetermined period of time. This temperature is typical for polyester,
Moreover, for polyethylene terephthalate, which is known to have a slow crystallization rate, a temperature in the range of 120 to 180°C is suitable. By applying such a method, the effects of the present invention can be easily obtained. In this case, the diameter of the foam is not limited to this range, but as a guide, the diameter is in the range of 13D ² <t1/2 (2). Of course, in the case of an effective diameter outside the range shown by formula (2), it is preferable to select an appropriate temperature atmosphere to promote crystallization, and this can be carried out within the scope of the spirit of the present invention. Aromatic polyester string foam is 1 mm ² or
It has a cross-sectional area of 200mm ² . That is, if it is smaller than 1 mm ² , no foaming occurs, most of it becomes a skin layer, and an effective foam cannot be obtained. On the other hand, string-like foams larger than 200 mm ² lose their bendability, making it difficult to process such as weaving and knitting, and unable to perform their original functions. A more preferable range of cross-sectional area is 3 to 150 mm ² . Here, the most common cross-sectional shape is circular, oblong, or a rectangular shape.
Although it is possible to produce a die with a star shape or other irregularities, the shape approaches the above shape due to expansion during foaming. Film and sheet-like materials are excluded here, so those with a major axis/minor axis or width/thickness of 10 or less are assumed. Here, the effective diameter is

It is defined as [Formula] (where D: effective diameter, S: cross-sectional area, π: pi). A die for producing a foamed continuous body having a cross-sectional area of 1 mm ² to 200 mm ² is designed by conducting simple preliminary experiments taking into consideration the balancing effect of the molten composition, expansion ratio, appropriate draft, etc. can do. The string-like foam obtained according to the present invention contains stabilizers,
Dyes and pigments, foaming nucleating agents, flame retardants, antistatic agents, and other additives may be included as desired, but in this case, the effect of these additives on the semi-crystallization time should be taken into consideration before cooling. You have to choose a method. The string-like foam obtained by the present invention has sufficient strength and heat resistance for its corresponding specific gravity. The present invention will be explained in more detail with reference to Examples below. Example 1 100 parts by weight of polyethylene terephthalate pellets with an intrinsic viscosity (measured at 35°C using orthochlorophenol solvent) of 0.65 were dried with hot air at 130°C for 8 hours, and then 0.6 parts by weight of 1,2-diglycidylhexahydrophthalate was added. and 0.5 part by weight of talc as a foam nucleating agent were mixed using a V-type blender to uniformly adhere 1,2-diglycidylhexahydrophthalate and talc as a foam nucleating agent to the pellets. The pellets obtained above were put into a cylinder with a diameter of 40 mm.
It was extruded and foam-molded using an extrusion foam molding machine equipped with a die having 8 nozzles with a diameter of 1.5 mm and a diameter of 1.5 mm. In extrusion foam molding, 15 parts by weight of dichlorodifluoromethane (per 100 parts by weight of polymer) is injected into the center of the cylinder of the molding machine using a plunger pump, and the cylinder temperature is set at 280°C in the supply zone for plasticization. The temperature was set at 280°C in the zone, 270°C in the metering zone, and 270°C in the die part, and the screw rotation speed was 25 rpm and the discharge pressure was 80 kg/cm ² . Foamed molded bodies with different average diameters were obtained by taking the foam at different draft rates. The result is the first
Shown in the table.

[Table] Comparative Example 1 Foam molding was carried out in the same manner as in Example 1 except that the cooling method was changed. Table 2 shows the relationship between the manufacturing conditions and the physical properties of the obtained foam.

[Table] It can be seen from the above table that an inappropriate cooling method resulted in a foam with low crystallinity, deformation at 100°C, and low heat resistance. Example 2 100 parts by weight of polyethylene terephthalate pellets with an intrinsic viscosity of 0.65 were dried with hot air at 130°C for 8 hours, and then 0.8 parts by weight of diglycidyl ether of 2,2-bis(4-hydroxyphenyl)propane and sodium montanate were added. The pellets were uniformly mixed with 0.3 parts by weight and 0.5 parts by weight of talc in a V-type blender, and the additives were sprinkled onto the pellets. The obtained pellets were extruded through a die having eight nozzles with a hole diameter of 1.5 mm using a tandem extruder having cylinder diameters of 40 mm and 50 mm, and were foam-molded. In foam molding, 7 parts by weight of carbon dioxide gas (polyethylene terephthalate 100%
It was press-fitted at 45 kg/cm ² (per weight part). The extrusion conditions are
The cylinder temperature of the first extruder was set at 280°C, the cylinder temperature of the second extruder was set at 265°C, and the die temperature was set at 270°C. The screw rotation speed was 30 rpm for the first extruder and 23 rpm for the second extruder, and the extrusion pressure was 100 Kg/cm ² . Here, sodium montanate was added as a thickening reaction accelerator, and talc was added as a foaming nucleating agent, both of which are substances conventionally known as crystal nucleating agents for polyethylene terephthalate. The relationship between the manufacturing conditions and the physical properties of the obtained foam is explained in the third section.
Shown in the table.

[Table] Example 3 100 parts by weight of polybutylene terephthalate pellets having an intrinsic viscosity (measured at 35°C in orthochlorophenol solvent) of 1.45 obtained by solid-phase polymerization were
After drying with hot air at 130°C for 8 hours, it was evenly sprinkled with 0.5 parts by weight of talc as a foaming nucleating agent using a V-shaped blender, and then a cylinder diameter of 40 mm, L/D 32
Extrusion foam molding was carried out using an extrusion foam molding machine equipped with a die having eight nozzles with a hole diameter of 1.5 mm. In the extrusion foam molding, a mixed blowing agent of methylene chloride: trichlorotrifluoroethane (Freon 113) = 1:3 was injected at a ratio of 15 parts by weight (per 100 parts by weight of polymer) using a plunger pump. In addition, the cylinder temperature is 220℃ in the supply zone,
The plasticizing zone was set at 240℃, the metaling zone was set at 240℃, and the die section was set at 230℃, and the screw rotation speed was
The engine speed was 35 rpm and the discharge pressure was 75 kg/cm ² . Table 4 shows the manufacturing conditions and the physical properties of the obtained foam.

[Table] Example 4 Effective diameter 0.25 cm and foaming ratio obtained in Example 1
Blind weaving was carried out using 11x string foam as the weft and polyester fiber as the warp to create blinds with 35 threads per 10 cm. The resulting bamboo blinds weighed 250g/m ² and were light.
It had sufficient strength for use. Moreover, the strength of the single yarn was 40Kg/cm ² . Example 5 Expansion ratio 1.0 times and effective diameter obtained in Example 2
A 0.85 cm string-like foam was plain woven. Hot asphalt at 230°C was applied onto a 10cm x 10cm concrete plate, and the foamed polyester fabric was pressed onto it while it was still hot. The foamed polyester fabric was in close contact with the asphalt and did not undergo deformation such as blistering or warping. This result indicates that the fabric can be used as a heat insulating material for concrete roofs.

Claims (1)

[Claims] 1. An aromatic polyester melt containing 1 to 50% by weight of a substance with a boiling point of 90°C or less at normal pressure and having a foaming ability of 8000 poise or more with a melt viscosity at a temperature 15°C higher than the melting point was extruded from a die. A string-shaped aromatic polyester foam continuum having a cross-sectional area of 1 mm ² to 200 mm ² , characterized in that it is treated to have a crystallinity of 30% or more of the crystallinity reached at a temperature that shows the maximum crystallization rate. manufacturing method.