JPH07207057A - Production of thermoplastic polyester resin foam - Google Patents

Abstract

PURPOSE:To produce thermoplastic polyester resin foam while preventing the formation of a heat decomposition product of the resin by adding a cross-linking agent and a specified olefin resin to the polyester resin, melting the mixture by heating, and foaming the melt by injecting a blowing agent. CONSTITUTION:A cross-linking agent, 0.1-2wt.% olefin resin having a melting point of 140 deg.C or below and a melt flow rate of 10g/10min or above (at 230 deg.C) and optionally a compound of a metal of group 1 or 2 in the periodic table are added to a thermoplastic polyester resin to obtain a resin composition. This composition is fed into an extruder, melted by heating and extruded and foamed by injecting a blowing agent.

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 thermoplastic polyester resin foam.

[0002]

2. Description of the Related Art A thermoplastic polyester resin is a high molecular weight linear polyester produced by an esterification reaction between an aromatic dicarboxylic acid and a dihydric alcohol, that is, a diol. As the carboxylic acid, phthalic acid, especially terephthalic acid, was often used, and as the diol, ethylene glycol and butylene glycol were often used. Therefore, a typical thermoplastic polyester resin is polyethylene terephthalate,
It is polybutylene terephthalate. Here, such a thermoplastic polyester resin is abbreviated as PAN.

PAN has excellent properties not found in other resins. That is, PAN has high mechanical strength, good shape stability, and excellent heat resistance to withstand 200 ° C. Further, PAN is a crystalline resin, and a molded product having different crystallinity is produced depending on the molding method, and the higher the crystallinity, the higher the heat resistance and the rigidity. However, PAN is easy to print. Since the ease of adhesion and the ease of secondary workability are reduced, the properties of the molded product can be changed to some extent according to the purpose. As described above, PAN has excellent properties and is widely used as a container such as a bottle.

However, PAN has not been widely used as a foam. The reason is that PAN is a resin that is difficult to foam. Generally, foaming of resin is most often carried out by extrusion foaming. Therefore, the reason why it is difficult to foam PAN will be explained as follows. Originally, since PAN is a crystalline resin, when it is heated, it has the property of rapidly melting at a temperature at which the crystals disappear and becoming a liquid with low viscosity. Therefore, it is difficult for the PAN to have viscoelasticity suitable for foaming, even if the PAN is melted and the foaming agent is included in the melted material. For example, even if a foaming agent is contained in PAN, the foaming agent will immediately escape from the PAN. Therefore, PAN could not foam it uniformly and at high magnification.

Therefore, attempts have been made to give PAN foaming suitability. For example, by increasing the degree of polymerization of PAN to increase the melt viscosity, or by copolymerizing a branching agent, high viscosity PAN can be obtained.
It was tried to make. However, these attempts failed to give the PAN viscoelastic properties suitable for foaming.

In addition, attempts have been made to increase the melt viscosity of PAN by mixing PAN with various substances. For example, a diepoxy compound as a crosslinking agent to PAN,
It has been proposed to add a diglycidyl ester compound, an acid dianhydride and the like to extrude and foam. These proposals are disclosed in JP-A-54-70364 and JP-B-61-48.
No. 409, Japanese Patent Publication No. 5-47575. According to these proposals, it was possible to obtain a foam by extruding and foaming PAN.

Further, it has been proposed that a diglycidyl phthalate compound as a cross-linking agent and a metal compound of Groups 1 and 2 of the periodic table are added to PAN to extrude and foam a mixture thereof. This is Japanese Examination 5-5554
No. 3 publication. According to this proposal, PAN
Could be foamed uniformly and finely.

[0008]

However, the proposals taught by the above-mentioned publications have not been completely problem-free. This is because, when carried out by this proposal, the coloring matter that seems to be generated by the decomposition of PAN adheres to the surface of the foam and deteriorates the appearance of the foam. Therefore, it was necessary to improve this point. The present invention seeks to remedy such drawbacks.

[0009]

The present inventor has tried to extrude and foam the mixture by adding the above-mentioned various crosslinking agents to PAN in various proportions. That is, the above-mentioned crosslinking agent was added to PAN in various proportions, and the mixture thus obtained was put into an extruder, and a blowing agent such as butane was press-fitted into the mixture to extrude and foam. As a result, although the PAN foam obtained in this way is uniformly and finely expanded at a high magnification, it is unavoidable that the decomposed product of PAN adheres to the foam surface and impairs the appearance. Admitted. This drawback is that polyethylene-2 as PAN,
It was observed that this was remarkable when PAN having a high melting point such as 6-naphthalate was used.

The inventor has tried to add various materials to the above mixture to foam the PAN. As a result, when the present inventor added a specific amount of a specific olefin resin to PAN, when PAN was extruded and foamed, P
It was found that the decomposition of AN can be prevented. That is, the melting point of the olefin resin is 140 ° C. or less, and the load is 2.1.
If the melt flow rate at a temperature of 230 ° C. under a pressure of 6 kgf is selected to be 10 g / 10 minutes or more and the addition amount is kept within the range of 0.1 to 2% by weight with respect to PAN, the olefin system It has been found that the resin does not hinder the foaming of PAN and prevents the formation of heat decomposition products in PAN, and a good PAN foam can be obtained here. The present invention has been completed based on such knowledge.

According to the present invention, PAN (a) a cross-linking agent,
(B) an olefin resin having a melting point of 140 ° C. or less and a melt flow rate at 230 ° C. of 10 g / 10 minutes or more is added to adjust the amount of the olefin resin to 0.1 to 2% by weight based on the PAN. It is intended to provide a method for producing a PAN foam, which is characterized in that the obtained mixture is put into an extruder, and the mixture is melted in the extruder and a foaming agent is pressed into the extruder to extrude and foam.

The present invention is characterized in that a crosslinking agent is added to PAN. Compared to other thermoplastic resins such as polyethylene and polystyrene, PAN containing a cross-linking agent is extruded at a high temperature and is therefore easily decomposed by heat.
However, in the present invention, since the specific olefin resin is added in a specific amount, the olefin resin acts as a lubricant between the PAN molecules and between the barrel and screw of the extruder and the PAN, so that excessive heat generation is caused. Is suppressed, and the generation of PAN decomposition products disappears. As a result, it is possible to obtain a PAN foam that is uniformly and finely foamed and has a good appearance.

The PAN that can be used in the present invention is
As already mentioned, it is a high molecular weight chain polyester obtained by condensation of an aromatic dicarboxylic acid and a diol. As the dicarboxylic acid, in addition to terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyletherdicarboxylic acid, diphenoxydicarboxylic acid can be used. As the diol, in addition to ethylene glycol, trimethylene glycol, tetramethylene glycol, cyclohexane dimethylol, 2,2-bis (4-β-hydroxyethoxyphenyl) propane and the like can be used. PA like this
N is commercially available. In the present invention, such commercially available P
AN can be used.

The reason why the crosslinking agent is added in the present invention is to increase the viscosity of PAN during melting. Various crosslinking agents can be used. Among the crosslinking agents, it is preferable to use an acid dianhydride or a polyfunctional epoxy compound. The acid dianhydrides are roughly classified into aromatic acid dianhydrides, cycloaliphatic acid dianhydrides, aliphatic acid dianhydrides, and halogenated acid dianhydrides, and any of them can be used. Aromatic acid dianhydride is, for example, pyromellitic dianhydride, benzophenone tetracarboxylic acid dianhydride, naphthalene tetracarboxylic acid dianhydride, diphenyl sulfone tetracarboxylic acid dianhydride, cyclic aliphatic acid dianhydride is Cyclopentanetetracarboxylic acid dianhydride, aliphatic acid dianhydride is, for example, 1,2,3,4-butanetetracarboxylic acid dianhydride, and halogenated acid dianhydride is, for example, 1,4-dibromo. It is benzenetetracarboxylic dianhydride. Of these, aromatic dianhydrides, particularly pyromellitic dianhydride, are preferably used.

As the polyfunctional epoxy compound, diglycidyl terephthalate, diglycidyl orthophthalate,
Diglycidyl hexahydrophthalate, 4-functional nitrided epoxy (for example, TETRAD-D manufactured by Mitsubishi Gas Chemical Company), polyethylene glycol diglycidyl ether, polypropylene diglycidyl ether, bisphenol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexane Diol diglycidyl ether, glycerin diglycidyl ether, trimethylolpropane triglycidyl ether, hydrogenated BP-A diglycidyl ether and 2,2-dibromoneopentyl glycol diglycidyl ether can be used. Among them, diglycidyl terephthalate, diglycidyl orthophthalate, diglycidyl hexahydrophthalate, 4
Functionalized nitrided epoxies are particularly preferred.

In the present invention, in order to further increase the viscosity of PAN during melting, it is preferable to add a metal compound of Group 1 or 2 of the periodic table together with the above-mentioned crosslinking agent. This metal compound may be an organic compound or an inorganic compound. As the inorganic compound, potassium chloride, sodium chloride, potassium carbonate, sodium carbonate, zinc carbonate, magnesium carbonate, calcium carbonate or the like can be used. As the organic compound, lithium stearate, sodium stearate, potassium stearate, zinc stearate, magnesium stearate, calcium stearate, lithium montanate,
Sodium montanate, potassium montanate, zinc montanate, magnesium montanate, calcium montanate, lithium acetate, sodium acetate, potassium acetate, zinc acetate, magnesium acetate, calcium acetate, lithium caprylate, sodium caprylate, potassium caprylate, Zinc caprylate, magnesium caprylate, calcium caprylate, lithium myristate, sodium myristate, potassium myristate, zinc myristate, magnesium myristate, calcium myristate, lithium toluenesulfonate, sodium toluenesulfonate, potassium toluenesulfonate, potassium toluenesulfonate Etc. can be used. Among these, lithium, sodium,
Preference is given to using potassium compounds.

The olefinic resin which can be used in the present invention must have a melting point of 140 ° C. or lower. Such olefin resins include low density polyethylene, medium density polyethylene, high density polyethylene,
Linear low density polyethylene, ionomer, propylene
There are ethylene random copolymers and ionomer resins.
However, since polypropylene has a melting point of 170 ° C.,
Not suitable for use in this invention. These olefin resins can be used alone or in combination. In addition,
As the ionomer, for example, a molecule of ethylene / methacrylic acid copolymer is bonded with a metal ion between the molecules to obtain 82-96.
Those having a melting point of ° C (Mitsui DuPont Co., Ltd., Himilan 1707, 1555, etc.) can be used.

The olefin resin that can be used in the present invention must have a specific melt flow rate as well as a melting point. The condition for measuring the melt flow rate is 2.1 according to JIS K 7210.
A temperature of 230 ° C. shall be taken under a load of 6 kgf. The olefin resin should have a melt flow rate of 10 g / 10 minutes or more under the conditions. The reason is that if an olefin resin having a melting point of more than 140 ° C. or a melt flow rate of less than 10 g / 10 min is used, it is impossible to suppress the generation of decomposition products in the extruded foam of PAN. .

The above-mentioned olefin resin is added in an amount of P
It is necessary to be within the range of 0.1 to 2% by weight with respect to AN. The reason is that if the amount is less than 0.1% by weight, the effect due to the addition of the olefin resin is not remarkable.
This is because it is not well dispersed in AN and the resulting foam has a poor appearance.

The above-mentioned olefin resin is generally a PAN.
Not compatible with. Therefore, this olefin resin is
When added to AN, it is preferable to use a powdered olefin resin rather than a pelletized one. Whether the olefin resin is in the form of pellets or powder, it is added to the PAN by first mixing the olefin resin with PAN and putting the resulting mixture in an extruder, especially twin screw extrusion. It is preferable to put it in a machine and knead well to prepare a masterbatch, which is then added to PAN.

In the present invention, the PAN is melted in the extruder, and the foaming agent is pressed into it. Various foaming agents can be used at this time. The blowing agents that can be used can be roughly classified into inert gas, saturated aliphatic hydrocarbon, saturated alicyclic hydrocarbon, aromatic hydrocarbon, halogenated hydrocarbon, ether, and ketone. As the inert gas, carbon dioxide, nitrogen or the like can be used, and as the saturated aliphatic hydrocarbon,
Methane, ethane, propane, butane, pentane, hexane and the like can be used, and as the saturated alicyclic hydrocarbon, methylcyclopropane, cyclopentane, 1,1-
Dimethylcyclopropane, cyclohexane, methylcyclopentane, ethylcyclobutane, 1,1,2-trimethylcyclopropane, etc. can be used, benzene can be used as the aromatic hydrocarbon, and trichloromonochloride can be used as the halogenated hydrocarbon. Fluoromethane, dichlorofluoromethane, monochlorodifluoromethane, trichlorotrifluoroethylene, dichlorotetrafluoroethylene, etc. can be used, dimethyl ether, methyl tertiary butyl ether, etc. can be used as the ether, and acetone, ethylmethyl as the ketone. Ketone, acetylacetone, etc. can be used. These foaming agents are preferably used in a proportion of 0.03 to 7% by weight with respect to PAN, of which 0.0
A ratio of 5 to 5% by weight is particularly preferable.

In the present invention, various additives conventionally used can be added to the melt of PAN. Examples of the additive include an ultraviolet absorber, an antistatic agent,
Crystal nucleating agents, foam nucleating agents, coloring agents, flame retardants and the like.

A single-screw extruder is preferably used as an extruder for extruding and foaming PAN. However,
When the olefin resin is premixed with PAN to be used as a masterbatch, it is preferable to use a twin-screw extruder. In an extruder for foaming by extrusion, a foaming agent pressure inlet is provided in the middle of the barrel, and the foaming agent is pressed in from this. The extruder preferably extrudes and foams while maintaining the temperature of the barrel at a temperature 5 to 30 ° C. higher than the melting point of PAN, especially 10 to 25 ° C. higher.

[0024]

According to the present invention, since a mixture of PAN and a cross-linking agent is put into the extruder, the PAN melted in the extruder has a viscosity suitable for foaming and, therefore, is easily extruded and foamed. Has become. In this invention, an olefin resin having a melting point of 140 ° C. or lower and a melt flow rate at 230 ° C. of 10 g / 10 min or more is added to the PAN, so that the olefin resin is the same as the PAN and the inner and outer surfaces of the barrel of the PAN and the extruder. And acts as a lubricant between them, so that excessive heat generation inside the PAN is suppressed and decomposition is prevented. Further, since the amount of the olefin resin is 0.1 to 2% by weight with respect to the PAN, the olefin resin has a proper lubricating effect, and the olefin resin is compatible with the PAN and has a good appearance. Is obtained. In this respect, the present invention has a remarkable effect.

[0025]

EXAMPLES The advantages 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". In the following, the term "sea urchin" refers to a red bean-sized brown-colored decomposition product produced in the foamed sheet by decomposition of PAN. It is considered that the eye die is generated mainly by the frictional heat between the resin and the mold wall surface.

[0026]

Example 1 In this example, as PAN, polyethylene-2,6-naphthalate (melting point: 267 ° C., intrinsic viscosity: 0.
549 dl / g) and an ethylene resin (manufactured by Shamrock, trade name CERALUBE4NA, melting point 114 ° C., particle size 5 μm, melt flow rate 10 as an olefin resin.
0 g / 10 min or more) was used to prepare the following composition. Thermoplastic polyester resin 100 parts Ethylene resin powder 1.0 part Pyromellitic dianhydride 0.40 parts Sodium carbonate 0.05 parts

The above composition was put into a 65 mmφ single-screw extruder, the temperature of the feeding section of the extruder was 280 ° C., the temperature of the compression section was 290 ° C., and the temperatures of the melting section, the head section and the die were all 230. ℃ was made. Butane as a foaming agent was press-fitted at a rate of 0.90% by weight from the middle of the barrel of the extruder and extruded from the mouthpiece into the atmosphere.

An annular extrusion hole was provided in the die, and the diameter of the extrusion hole was 80 mm and the gap was 0.4 mm. Further, a plug having a diameter of 205 mm and a length of 740 mm is provided at the tip of the mouthpiece, cold water is circulated in the plug to cool the plug, and the thermoplastic polyester resin foam slides on the plug. Thus, the thermoplastic polyester resin foam was rapidly cooled. The annular sheet thus obtained was cut open to obtain a flat thermoplastic polyester resin foam sheet.

The obtained thermoplastic polyester resin foamed sheet was recognized as a good quality foamed body having a uniform density of 0.22 g / cc. Further, no eye blemishes occurred at all within 2 hours from 4 hours after the start of extrusion.

[0030]

Example 2 Polyethylene-2,6 used in Example 1
80% by weight of naphthalate and 20% by weight of low density ethylene resin (trade name: YM-61, manufactured by Mitsubishi Petrochemical Co., melting point 114 ° C., melt flow rate 15.0 g / 10 min) were mixed with a twin-screw extruder having a diameter of 30 mm. Pellets, so-called master batches were prepared.

Polyethylene-2,6 used in Example 1
The following composition was made using naphthalate and pellets containing 20% by weight of ethylene resin obtained by the above method. Thermoplastic polyester resin 100 parts Ethylene resin kneaded masterbatch 0.75 parts Pyromellitic dianhydride 0.42 parts Sodium carbonate 0.05 parts

A foamed sheet was prepared by extruding the above composition in the same manner as in Example 1.

The obtained thermoplastic polyester resin foam sheet was recognized as a good quality foam having a density of 0.22 g / cc and being uniformly foamed. Further, no eye blemishes occurred at all within 2 hours from 4 hours after the start of extrusion.

[0034]

Example 3 Polyethylene-2,6 used in Example 1
An extruded foam sheet was produced in the same manner as in Example 1 using polyethylene terephthalate (melting point 257 ° C., intrinsic viscosity 0.75 dl / g) instead of naphthalate.

The obtained thermoplastic polyester resin foam sheet was recognized as a good quality foam having a density of 0.22 g / cc and uniformly foamed. Further, no eye blemishes occurred at all within 2 hours from 4 hours after the start of extrusion.

[0036]

Example 4 Instead of the pyromellitic dianhydride and sodium carbonate used in Example 1, 0.4 parts by weight of tetrafunctional nitride epoxy (trade name TETRAD-D manufactured by Mitsubishi Gas Chemical Co., Inc.) was used. An extruded foam sheet was produced in the same manner as in (1).

The obtained foamed sheet has a density of 0.25 g.
/ Cc was recognized as a high-quality foam having a uniform foam. Further, no eye blemishes occurred at all within 2 hours from 4 hours after the start of extrusion.

[0038]

Comparative Example 1 This comparative example is an example in which a good result was not obtained because a polyolefin resin having a high melting point was used. Instead of the polyethylene resin used in Example 2, polypropylene resin (Sumitomo Chemical Co., Ltd., trade name AZ56
4, melt flow rate 30g / 10min, melting point 1
(63 ° C.) was used to prepare pellets in the same manner as in Example 2. Furthermore, the obtained pellets had the same composition as in Example 2,
An extruded foam sheet was produced by the method.

The obtained thermoplastic polyester resin foamed sheet had a density of 0.22 g / cc and was uniformly foamed. Therefore, in this respect, it was recognized as a good quality foamed body. However, 98 eye dips occurred within 2 hours from the start of extrusion for 4 hours. Therefore, the foam was not of good quality.

[0040]

Comparative Example 2 This comparative example is an example using polyethylene having a low melt flow rate. Instead of the polyethylene resin used in Example 2, ethylene resin (manufactured by Mitsubishi Yuka Co., Ltd.,
Pellets were produced in the same manner as in Example 2, using a trade name of AZ564, melting point of 109 ° C., melt flow rate of 8.5 g / 10 min). Further, the obtained pellets were extruded with the same composition and method as in Example 2 to prepare a foam sheet.

The obtained thermoplastic polyester resin foamed sheet had a density of 0.22 g / cc and was uniformly foamed. Therefore, in this respect, it was recognized as a good quality foamed body. However, 37 eye dips occurred within 2 hours from 4 hours after the start of extrusion. Therefore, a good foamed sheet could not be obtained as a whole.

[0042]

[Comparative Example 3] The polyethylene resin (Sh
Amrock, product name CERALUBE4NA) instead of low density polyethylene resin pellets (Mitsubishi Yuka, product name Y)
M-61, melting point 114 ° C, melt flow rate 1
An extruded foam sheet was prepared in the same manner as in Example 1 using 5.0 g / 10 min and an average particle size of about 3 mm).

The obtained thermoplastic polyester resin foamed sheet had a density of 0.22 g / cc, but the polyethylene resin dispersibility was poor and only a sheet having a bad surface was obtained. In addition, 6 eye blemishes were generated within 2 hours from 4 hours after the start of extrusion. Therefore, this foam was not good.

[0044]

COMPARATIVE EXAMPLE 4 This comparative example is an example in which the amount of the olefin resin used is larger than the specified amount. An extruded foam sheet was produced in the same manner as in Example 2 except that the amount of the polyethylene kneading masterbatch was 12.5 parts.

The obtained thermoplastic polyester resin foamed sheet had a density of 0.22 g / cc, but the dispersibility of the polyethylene resin was poor and only a sheet having a bad surface was obtained.

Claims (1)

[Claims] 1. An olefin resin comprising a thermoplastic polyester resin, (a) a crosslinking agent, and (b) an olefin resin having a melting point of 140 ° C. or less and a melt flow rate at 230 ° C. of 10 g / 10 minutes or more. The amount of the resin is 0.1 to 2% by weight with respect to the thermoplastic polyester resin,
A method for producing a thermoplastic polyester-based resin foam, characterized in that the mixture thus obtained is put into an extruder, and the mixture is melted in the extruder and a foaming agent is pressed into the mixture to extrude foam.