JPH0316977B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing thermoplastic polyester foams. Polyethylene terephthalate and polybutylene terephthalate have mechanical properties, heat resistance, chemical resistance,
Due to its excellent dimensional stability, injection molded products,
Used for blow molded products, fibers, films, etc.
However, when trying to produce a thermoplastic polyester resin foam by extrusion foaming, the melt viscosity is small and no back pressure is applied, and the gas from the blowing agent escapes, making it impossible to obtain a good foam. In the manufacturing method described in JP-A-54-50568, a diepoxy compound and a montan wax salt or a montan wax ester salt are mixed with a thermoplastic polyester resin to increase the melt viscosity of the thermoplastic polyester resin. However, these methods require the use of metals from groups a and a of the periodic table, or their compounds, which act to promote the reaction of diepoxy compounds, and the thickening reaction of diepoxy compounds is significantly accelerated; The disadvantage is that the increase is too rapid and the viscosity is not stable enough, reaching the maximum viscosity quickly and then rapidly decreasing, resulting in a narrow optimum operating range. In addition, in the manufacturing method described in JP-A No. 57-20333,
In order to improve the above-mentioned drawbacks, it has been proposed to mix 0.1 to 3% by weight of a diglycidyl ester compound into the thermoplastic polyester resin. Compared to the above-mentioned method, this method does not require the use of metals from groups a and a of the periodic table or their compounds, and uses a diglycidyl ester compound alone, so there is no need to use metals from groups a and a of the periodic table, and the color deterioration that occurs in the case of the above-mentioned method is avoided. Good foams can be obtained because no foaming occurs and the stability of the melt viscosity is excellent, but there is a limit to obtaining products with a high expansion ratio or a large cross-sectional area, and only those with coarse cells can be obtained. I had a problem with not being able to get it. The present invention improves the above-mentioned drawbacks of the prior art, and has a large effect of increasing melt viscosity, has a stable thickening effect, and can easily produce products with a uniform and high expansion ratio and a large cross-sectional area. The purpose is to provide a method that can be obtained. The gist of the present invention is thermoplastic polyester resin, polyfunctional glycidyl ester compound 0.03 to 2.5 mol% to thermoplastic polyester resin, polyfunctional carboxylic acid anhydride 0.01 to 2.5 mol% to thermoplastic polyester resin.
The present invention relates to a method for producing a thermoplastic polyester resin foam, which comprises mixing 2 mol % of a foaming agent with a foaming agent having a boiling point of 150° C. or less at normal pressure and extrusion foaming. The thermoplastic polyester resin used in the present invention is a linear polyester of a polycondensate of a dicarboxylic acid component and a diol component. Dicarboxylic acid components include terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenoxyethane dicarboxylic acid, etc., and diol components include ethylene glycol. , trimethylene glycol, tetramethylene glycol, hexamethylene glycol, neopentylene glycol, hexamethylene glycol, cyclohexane dimethylol, tricyclodecane dimethylol,
These include 2,2-bis(4-β-hydroxyethoxyphenyl)propane, 4,4'-bis(β-hydroxyethoxy)diphenylsulfone, diethylene glycol, and the like. Therefore, suitable thermoplastic polyester resins for use in the present invention include polyethylene terephthalate, polybutylene terephthalate, polybutylene terephthalate elasmer, amorphous polyethylene terephthalate, etc. 85 acid
% or more is desirable. In the present invention, the thermoplastic polyester resin is
It is preferable that the intrinsic viscosity is 0.4 or more and 1 or less from the viewpoint of ease of molding. The first compound that exhibits the effect of increasing the melt viscosity of the thermoplastic polyester resin in the present invention is a polyfunctional glycidyl ester compound. Some specific compounds include diglycidyl terephthalate, diglycidyl-o-phthalate, 3,4 epoxycyclohexylmethyl-3,
-( _CH ) ₄ − is replaced with the following. [−(CH ₂ ) ₃ −,

[Formula] −CH ₂ −CH = CH−CH ₂ −, −CH ₂ −CH=CH− (CH ₂ ) ₂ −CH
=CH− _CH2− ,

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[Formula]] (R′ is

[Formula] The polyfunctional glycidyl ester compound has an excellent thickening effect on thermoplastic polyester resins compared to the polyfunctional glycidyl ether compound. Figure 1 shows the comparison. The thermoplastic polyester resin is polyethylene terethalate (manufactured by Kanebuchi Chemical Co., Ltd.)
EFG-6), and the melt viscosity is 260℃ shear rate γ〓
= 68.7sec ^-1 . ~ in Figure 1
is a mixture of diglycidyl ether compounds, including bisphenol A-type diepoxy (Epicote 828 manufactured by Yuka Shell Co., Ltd.), 1,6-hexanediol diglycidyl ether (Epolite #1600 manufactured by Kyoeisha Yushi Co., Ltd.), and trimethylolpropane triglycidyl. Ether (Epolite #100MF manufactured by Kyoeisha Yushi Co., Ltd.) has no thickening effect when used alone, suggesting that it is necessary to use it in combination with a metal or its compound. On the other hand, diglycidyl terephthalate (Blenmar DGT manufactured by NOF Corporation), diglycidyl-θ-phthalate (Blenmar DGT manufactured by NOF Corporation),
DGP), 7,8-diphenyltetradecane-
1,14-dicarboxylic acid diglycidyl ester (Okamura Oil Co., Ltd. OS Resin ST-2PG), 6-ethylhexadecane-1,16-dicarboxylic acid diglycidyl ester (Okamura Oil Co., Ltd. OS Resin SB-20G),
3,4 epoxycyclohexylmethyl-3,4
Epoxycyclohexane carboxylate (ERL-4221, manufactured by Union Carbide) shows good thickening effects on thermoplastic polyester resins. The amount of polyfunctional glycidyl ester compound mixed with thermoplastic polyester resin is 0.03 to 2.5 mol.
done to %. If it is less than 0.03 mol %, the thickening effect will be so small that no synergistic effect with the polyfunctional carboxylic acid anhydride can be expected. When it exceeds 2.5 mol%, the thickening effect is large and gelation occurs during extrusion molding. More preferably, the amount of the polyfunctional diglycidyl ester compound mixed is 0.07 to 1 mol% based on the thermoplastic polyester resin. In the present invention, the molecular weight of the thermoplastic polyester resin means the average molecular weight determined from the intrinsic viscosity. The molecular weight of polyethylene terephthalate used in the above experiment was 2×10 ⁴ . The second compound that exhibits the effect of increasing the melt viscosity of the thermoplastic polyester resin in the present invention is a polyfunctional carboxylic acid anhydride. The reason why it is made into an anhydride is to prevent water from being generated and hydrolyzing the thermoplastic polyester resin when the polyfunctional carboxylic acid is condensed with the terminal group of the thermoplastic polyester resin. Specific examples of the polyfunctional carboxylic anhydride include pyromellitic anhydride, trimellitic anhydride, phthalic anhydride, maleic anhydride, isophthalic anhydride, naphthalenetetracarboxylic anhydride, and maleic anhydride. The polyfunctional carboxylic acid anhydride tries to bond to the -OH group at the end of the thermoplastic polyester resin, but
At the same time, it is thought that the entangled crosslinked structure becomes larger at the bonding site between the thermoplastic polyester resin and the polyfunctional glycidyl ester compound, thereby exerting a synergistic effect of increasing viscosity. FIG. 2 shows the synergistic effect of a polyfunctional glycidyl ester compound and a polyfunctional carboxylic acid anhydride. Polyethylene terephthalate (EFG-6 manufactured by Kanebuchi Chemical Co., Ltd.) 100 as thermoplastic polyester resin
The graph shows the change in melt viscosity when the mixing ratio is changed, with the total of dicrycidyl-θ-phthalate (Blenmar DGP manufactured by NOF Corporation) and pyromellitic anhydride being 0.5 parts by weight based on parts by weight. Melt viscosity is 260℃, shear rate γ = 68.7sec ^-1 , γ =
20.6sec ^-1 and γ=6.87sec ^-1 . The dotted line shows polyethylene terephthalate with only pyromellitic anhydride added. Figure 2 shows that a synergistic effect of thickening can be obtained by interposing a polyfunctional carboxylic acid anhydride together with a polyfunctional glycidyl ester compound, rather than by mixing only a polyfunctional glycidyl ester compound with a thermoplastic polyester resin. I understand. Diglycidyl-θ-phthalate here
0.5 parts by weight and 0.5 parts by weight of pyromellitic anhydride are each 0.35 mol relative to polyethylene terephthalate.
%, corresponds to 0.5mol%. In the present invention, the blowing agent is selected from those having a boiling point of 150° C. or lower at normal pressure. That is, inert gases, saturated aliphatic hydrocarbons, saturated alicyclic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, ethers, ketones, etc. can be used.
It is preferable to avoid using acids, alcohols, and esters due to their reactivity and decomposition properties. Specific examples of preferred blowing agents include carbon dioxide, nitrogen, helium, xenon, neon, methane, ethane, butane, hexane, cyclohexane, ethylcyclopentane, benzene, xylene, methyl chloride, methylene chloride, chloroform,
Carbon tetrachloride, ethyl chloride, dichloroethane, dichloroethylene, ethyl fluoride, ethane tetrafluoride, chlordifluoromethane, dichlorofluoromethane,
Examples include chlorotrifluoromethane, dichlorodifluoromethane, trichlorotrifluoroethane, tetrachlorodifluoroethane, fluorobenzene, chlorobenzene, methylal, acetal, acetone, ethylmethylketone, acetylacetone, and the like. Furthermore, in the present invention, a foaming nucleating agent such as talc, an inorganic filler including fibers, an antioxidant, a coloring agent, and the like may be appropriately mixed. The supply of polyfunctional glycidyl ester compounds and polyfunctional carboxylic acid anhydrides to thermoplastic polyester resins is as follows:
You can choose from several methods: (1) Thermoplastic polyester resin pellets are sprinkled with a polyfunctional glycidyl ester compound and a polyfunctional carboxylic acid anhydride, and the pellets are charged into the hopper of an extruder and melt-mixed. (2) First, either a polyfunctional glycidyl ester compound or a polyfunctional carboxylic acid anhydride and a thermoplastic polyester resin are melt-mixed to form pellets, and the pellets are mixed with the polyfunctional carboxylic acid anhydride or polyfunctional glycidyl ester. Melt mix with the remainder of the compound. (Extrusion is carried out in two stages) (3) A polyfunctional glycidyl ester compound and a polyfunctional carboxylic acid anhydride are simultaneously or separately added to the thermoplastic polyester resin melted in the extruder through the supply port provided in the cylinder of the extruder. put it into. In this case, a tandem extruder is used,
The polyfunctional glycidyl ester compound and the polyfunctional carboxylic acid anhydride can be separately charged into the supply port of the extruder at the front stage and the supply port of the extruder at the rear stage. The thickening effect when melt-mixing a polyfunctional glycidyl ester compound and a polyfunctional carboxylic acid anhydride with a thermoplastic polyester resin was confirmed using a two-stage extrusion method. The thermoplastic polyester resin is polyethylene terephthalate (EFG-6 manufactured by Kanebuchi Chemical Co., Ltd., intrinsic viscosity [] = 0.65, = 2 × 10 ⁴ ), and the polyfunctional glycidyl ester is diglycidyl-θ-phthalate (Blenmar DGP manufactured by Nihon Yushi Co., Ltd.). = A, the polyfunctional carboxylic acid anhydride is pyromellitic anhydride = B, A was mixed in the first stage and pelletized, B was newly mixed in the second stage, and the melt viscosity of the product was measured. . The extrusion conditions are a twin-screw extruder with a cylinder diameter of 30 mm and L/D = 25, and the temperature conditions are: supply zone 270 °C, plasticization zone 280 °C, melting zone 270 °C, die section 270 °C.
℃, and the extrusion rate was 5 kg/hour. The melt viscosity is 260°C and the shear rate γ = 68.7 sec ^-1 . Experimental example No. 1 corresponds to a comparative example. still,
The melt viscosity of the thermoplastic polyester resin alone was [ηa]=2×10 ³ poise.

[Table] From the above table, the thickening effect and synergistic effect of the polyfunctional glycidyl ester compound and the polyfunctional carboxylic acid anhydride were clarified. By melt-mixing the polyfunctional carboxylic acid anhydride, the thickening effect becomes greater. This is thought to be because if the polyfunctional carboxylic acid anhydride is added first, the acid anhydride tends to absorb moisture and further hydrolyze the thermoplastic polyester resin. The decrease in viscosity in the second stage of Experimental Example No. 1 is due to thermal deterioration. The blowing agent is fed to the thermoplastic polyester thickened in the final stage or to the thickened thermoplastic polyester in the first stage. Therefore, in the case of a two-stage extrusion method, the foaming agent may be mixed with pellets in the second stage, and the blowing agent may be introduced or press-fitted into the cylinder between the vent and die of the extruder near the final stage of extrusion. You may. According to the present invention, by mixing a specific amount of a polyfunctional glycidyl ester compound and a polyfunctional carboxylic acid anhydride with a thermoplastic polyester resin, a synergistic effect of thickening can be obtained, and the resin can be extruded with high back pressure. Even for products with large cross-sectional areas, fine, uniform foamed products can be obtained with a high expansion ratio of 20 to 30 times. In addition, the obtained product has a good appearance and has excellent mechanical strength, heat resistance, and chemical resistance, making it suitable for heat insulation materials used under extreme conditions such as high heat. . (Example) 100 parts by weight of polyethylene terephthalate and diglycidyl-θ- used in the experimental examples shown in Table 1 above.
Phthalate = 0.7 parts by weight of A (= 0.5 mol%) was melt-mixed using an extruder to obtain pellets under the extrusion conditions of Experimental Examples 1 and 2, and pyromellitic anhydride = 0.1 parts by weight of B (= 0.1mol%) (No.3), 0.3
Part by weight (=0.3 mol%) (No. 4), 0.5 part by weight of talc as a foaming adhesive, cyclohexane as a foaming agent
20 parts by weight were mixed and extruded and foamed using a second extruder. Extrusion conditions are cylinder diameter 40mm, L/D
=36 single screw extruder, temperature condition is feed zone 270
The temperature was 280°C in the plasticizing zone, 270°C in the melting zone, and 250-260°C in the die part. The obtained product had a good appearance. (Comparative Example) Extrusion foaming was carried out without adding pyromellitic anhydride as a secondary mixture. (No. 5) 0.3 parts by weight (=0.2 mol %) of diglycidyl-θ-phthalate as a second mixture was mixed in place of pyromellitic anhydride and foamed by extrusion. (No. 6) The above results are shown in Table 2.

[Table] From the above results, according to the present invention, products with a high expansion ratio can be stably obtained. Comparing the Comparative Example and the Example, with a die nozzle diameter of 2 mm, the Comparative Example has a lower foaming ratio than the Example, but can be molded, but with a die nozzle diameter of 4 mm, the foaming state becomes unstable and molding is difficult. On the other hand, in the examples, a high expansion ratio of 30 times is possible with a die nozzle diameter of 2 mm, and even with a die nozzle diameter of 4 mm, the expansion ratio is 20 times or more and the moldability is also good.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the thickening effect of a polyfunctional glycidyl ester compound on thermoplastic polyester resin. FIG. 2 is a graph showing the thickening effect of a polyfunctional glycidyl ester compound and a polyfunctional carboxylic acid anhydride on a thermoplastic polyester resin.

Claims (1)

[Scope of Claims] 1 Thermoplastic polyester resin, 0.03 to 2.5 mol% of a polyfunctional glycidyl ester compound to the thermoplastic polyester resin, and 0.01 to 2 mol% of a polyfunctional carboxylic acid anhydride to the thermoplastic polyester resin at normal pressure. A method for producing thermoplastic polyester resin foam, which is characterized by mixing a foaming agent with a boiling point of 150°C or lower and extrusion foaming. 2. Melting and mixing a polyfunctional glycidyl ester compound into a thermoplastic polyester resin,
Furthermore, polyfunctional carboxylic acid anhydride and boiling point of 150 at normal pressure.
A method for producing a thermoplastic polyester resin foam according to claim 1, which comprises mixing a foaming agent at a temperature of 0.degree. C. or below and extruding the foam.