JPS6157182B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for molding polyester resin. More specifically, when producing a molded article using a substantially linear saturated polyester powder, the present invention involves adding a compound having a specific chemical structure to the molded article before molding in order to impart improved performance to the molded article. The present invention relates to a method for molding polyester resin, which is characterized in that it is blended with polyester. Conventionally, saturated polyesters include polyalkylene terephthalates obtained from terephthalic acid and aliphatic glycols such as ethylene glycol, tetramethylene glycol, and hexamethylene glycol; for example, 2,2-bis(4'-hydroxyphenyl)propane; Polycarbonates obtained by reacting with phosgene; wholly aromatic saturated polyesters obtained from bisphenols and, for example, terephthalic acid or isophthalic acid, are well known. Each of these saturated polyesters has excellent chemical and physical properties, and taking advantage of these properties, they are widely used in fibers, films, plastics, and the like. In particular, when used as plastics, they have excellent electrical properties, chemical resistance, high impact resistance, heat resistance, etc., and their development in the field of so-called engineering plastics for industrial use is attracting attention. However, among the various properties of these saturated polyesters, the mechanical properties in particular are highly dependent on the degree of polymerization of the polymer, and for this reason, various methods have been studied and many proposals have been made to produce polyesters with as high a degree of polymerization as possible. There is. For example, when polyalkylene terephthalate obtained by a conventional method is further increased in degree of polymerization by solid phase polymerization, or when polyalkylene terephthalate is produced by melt polymerization, polymerization accelerators (e.g. diphenyl terephthalate, diphenyl carbonate, etc.) are used. A method using , etc. is well known. However, solid-phase polymerization is a method that focuses on suppressing side reactions during polymerization (for example, polymer chain scission caused by thermal decomposition reaction in high-temperature condensation reactions), and sacrifices the reaction rate to some extent.
The drawback is that it requires an extremely long reaction time and its productivity is low. In addition, methods using polymerization accelerators such as diphenyl terephthalate and diphenyl carbonate have the advantage of being able to obtain polymers with a high degree of polymerization in a short period of time, but on the other hand, by-products such as phenol are produced, so it is difficult to use them. It has the disadvantage that it must be distilled out of the reaction system and cannot be used practically unless the system is maintained at reduced pressure. Furthermore, as a method for manufacturing plastic molded objects using polyester, the raw material polyester is usually remelted, shaped through a die of a predetermined shape, and then cooled and solidified to produce a sheet,
Extrusion molding to form objects into shapes such as pipes and rods; Transfer molding and injection molding in which remelted polyester is injected into a mold of a predetermined shape and cooled and solidified;
Alternatively, a compression molding method is used in which polyester is filled into a mold, heated and melted under pressure to form a fluid shape, and then cooled and solidified. However, in all of these molding methods, it is necessary to remelt the polyester, and in this process, even if a polyester with a high degree of polymerization is used as the raw material polyester, the degree of polymerization inevitably decreases due to thermal decomposition. On the other hand, polyester powder is filled into a mold and pressurized to form a preform, and then the preform is exposed to a temperature lower than the melting point of the raw polyester in an inert atmosphere to coalesce the powder particles. A so-called powder molding method is known. However, since this method does not remelt the polyester during molding, the degree of polymerization of the molded product can be maintained at a fairly high level, but the mechanical strength of the resulting molded product does not necessarily give high results. There is a problem. The reason for this is probably due to the fine structural state inside the molded body, and is presumed to be caused by the fact that the powder particles of the raw polyester are not completely fused and integrated. As mentioned above, in order to improve the mechanical strength of polyester when used as a raw material for plastic molded objects, many methods have been proposed to increase the degree of polymerization and improve the molding method, but these methods have not always yielded satisfactory results. It hasn't been done yet. However, polyester molded articles used as engineering plastics may be required to have a high degree of moisture and heat resistance depending on their use. This moisture and heat resistance largely depends on the terminal carboxyl group content of the polyester, and therefore polyesters with low carboxyl group equivalents are desired. The present inventors focused on this point, and as a result of intensive study on how to solve the above-mentioned problems by adding a modifier when producing a molded article using saturated polyester as a raw material, we found that polyester powder The inventors have discovered that by using a polyester powder blended with a compound having a specific chemical structure in a molding method, the above-mentioned objects can be satisfied and extremely useful molded products can be obtained, and the present invention has been achieved. That is, the present invention uses 0.01 to 10% by weight of the following general formula () based on the saturated polyester (A). [However, in the formula, D is a divalent organic group, and n is 0
Or 1. X is a divalent organic group,

The ring structure of [Formula] is a group forming a 5-membered ring or a 6-membered ring. ] A powder of a polyester composition prepared by blending the compound (B) represented by is pressure-molded in a mold to obtain a preform, and then the preform is heated to a temperature higher than the melting point of the saturated polyester (A). This is a method for molding polyester resin, which is characterized by exposure to low temperatures. The saturated polyester (A) used in the present invention means a substantially linear saturated polyester. The acid components constituting the ester bonds of such saturated polyesters include terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl sulfone dicarboxylic acid,
Aromatic dicarboxylic acids such as diphenoxyethane dicarboxylic acid, diphenyl ether dicarboxylic acid, methyl terephthalic acid, methyl isophthalic acid, etc.;
Aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, etc.; alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; ε-oxycaproic acid,
Examples include oxycarboxylic acids such as oxybenzoic acid and hydroxyethoxybenzoic acid. Among these, aromatic dicarboxylic acids, particularly terephthalic acid and isophthalic acid, are preferred. Further, when the acid component constituting the saturated polyester is a dicarboxylic acid, examples of the glycol component include ethylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol, and cyclohexane dimethylol. Among these, ethylene glycol and tetramethylene glycol are particularly preferred. It is also possible to use polyoxyalkylene glycol as part of the glycol component, such as polyoxyethylene glycol, polyoxypropylene glycol, polyoxytetramethylene glycol, and copolymers thereof. When polyoxyalkylene glycol is used in combination, the preferred average molecular weight is 500~
5,000, more preferably 600 to 4,000, particularly preferably 800 to 3,000, and the amount used is approximately 5 to 85% by weight, preferably 10 to 80% by weight, more preferably 15 to 75% by weight in the polyester. be. Also, instead of the glycol component, aromatic dihydroxy compounds such as the general formula Bisphenols represented by (however, -X- is -
selected from the group consisting of O-, -S-, -SO ₂ -, -CO-, alkylene group, alkylidene group,
R ₁ , R ₂ , R ₃ , R ₄ , R ₁ ′, R ₂ ′, R ₃ ′ and R ₄ ′ are each selected from the group consisting of a hydrogen atom, a halogen atom, and a hydrocarbon group). Can be used. Such bisphenols include:
For example, 4,4'-dihydroxy-diphenyl ether, 4,4'-dihydroxy-2,2'-dimethyl-diphenyl ether, 4,4'-dihydroxy-3,
3′-dichlorodiphenyl ether, 4,4′-dihydroxydiphenyl sulfide, 4,4′-
Dihydroxy-diphenyl sulfone, 4,4'-dihydroxy-diphenyl ketone, 4,4'-dihydroxy-diphenyl-methane, 1,1-bis(4
-Hydroxyphenyl)-ethane, 2,2-bis(4-hydroxyphenyl)-propane, 1,1
-Bis(4-hydroxyphenyl)-n-butane, bis(4-hydroxyphenyl)-cyclohexylmethane, 1,1-bis(4-hydroxyphenyl)-2,2,2-trichloroethane, etc. can be mentioned. Among these, particularly preferred is 2,2-bis(4-hydroxyphenyl)-propane, ie, what is called bisphenol A. Further, these may be used alone, or as a mixture of two or more kinds, or a mixture of bisphenols and a small amount of other divalent compound. Typical polyesters comprising the acid component and a glycol component or an aromatic dihydroxy component include polyethylene terephthalate, polytrimethylene terephthalate, polytetramethylene terephthalate, polyhexamethylene terephthalate, poly 1,4-dimethylenecyclohexane terephthalate, and Copolymerized polyalkylene terephthalate containing these as main components; polyethylene naphthalene-2,6-dicarboxylate, polytetramethylene naphthalene-2,6-dicarboxylate, and copolymerized polyalkylene naphthalene dicarboxylate containing these as main components block copolymers of polyalkylene terephthalate and polyoxyalkylene glycol, such as block copolymers of polyhexamethylene terephthalate and polytetramethylene glycol;
Examples include fully aromatic polyesters made of bisphenol A and isophthalic acid, fully aromatic polyesters made of bisphenol A and an acid mixture of isophthalic acid and terephthalic acid, and copolymerized fully aromatic polyesters containing these as main components. . Among such saturated polyesters, fully aromatic polyesters have recently been called polyarylates and have even higher heat resistance, and are being used in a variety of industrial applications. Methods for producing such polyarylates have been known for a long time, such as interfacial polymerization (WMEareckson.J.Poly.Sci XL (399),
1959; Special Publication No. 40-1959); Solution polymerization (A.
Conix, Ind.Eng.Chem. 51 (147), 1959, Tokkosho
37-5599); Melt polymerization (Special Publication No. 38-15247,
Special Publication No. 43-28119). In addition, the above-mentioned saturated polyester is copolymerized with a trifunctional or higher functional compound such as trimethylolpropane, pentaerythritol, trimellitic acid, pyromellitic acid, etc. within a substantially linear range (for example, 1 mol% or less based on the total acid component). Alternatively, a part of the terminal group of the molecule may be blocked with a monofunctional compound such as benzoylbenzoic acid, diphenylcarboxylic acid, etc. In the present invention, the compound (B) to be blended with the above-mentioned saturated polyester (A) has the following general formula () [However, in the formula, D is a divalent organic group, and n is 0
Or 1. Also, X is a divalent organic group

The ring structure of [Formula] is a group forming a 5-membered ring or a 6-membered ring. ] It is indicated by. Among the compounds represented by the above general formula ()

A compound in which [Formula] is a 5-membered ring is called a bisoxazoline, and a compound in which the formula is a 6-membered ring is called a bisoxazine. In the above general formula, examples of X include ethylene, substituted ethylene, trimethylene, substituted trimethylene, etc. Substituents of substituted ethylene or substituted trimethylene include an alkyl group having 1 to 10 carbon atoms, and an aryl group having 6 to 12 carbon atoms. , carbon number 5~
Examples include a cycloalkyl group having 12 carbon atoms and an aralkyl group having 8 to 20 carbon atoms. More specifically, the alkyl group is methyl,
Ethyl, propyl, butyl, pentyl, hexamethyl, octamethyl, nonamethyl, decamethyl,
Examples include dimethylmethyl, and aryl groups include phenyl, naphthyl, diphenyl,

[Formula] (Here, R' is -O-, -CO -, -S-, -SO ₂ -, -CH ₂ , -CH ₂・CH ₂
--, --C(CH ₃ ) ₂ --, etc. ) etc. can be exemplified,
Moreover, cyclohexyl can be illustrated as cycloalkyl. Among these, X is ethylene,
Particularly preferred is trimethylene. D in the above general formula is a divalent organic group, for example, an alkylene group having 1 to 10 carbon atoms, or an alkylene group having 6 to 12 carbon atoms.
arylene group, a cycloalkylene group having 5 to 12 carbon atoms, an aralkylene group having 8 to 20 carbon atoms, and the like. More specifically, alkylene groups include methylene, ethylene, propylene, butylene, pentylene, hexamethylene, octamethylene, nonamethylene, decamethylene, dimethylmethylene, etc., and arylene groups include phenylene, naphthylene, diphenylene,

[Formula] (Here, R' is -O-, - CO-, -S-, -SO ₂ -, -CH ₂ -, -CH ₂ CH ₂
--, --C(CH ₂ ) ₂ --, etc. ) etc. can be exemplified,
Further, as the cycloalkylene group, cyclohexylene can be exemplified. Further, n in the formula is 0 or 1, but 0 is most preferable. Specific examples of these compounds include the following compounds. 2,2'-bis(2-oxazoline), 2,2'-bis(4-methyl-2-oxazoline), 2,2'-bis(4,4-dimethyl-2-oxazoline), 2,2'- Bis(4-ethyl-2-
oxazoline), 2,2'-bis(4,4-diethyl-2-oxazoline), 2,2'-bis(4-propyl-2-oxazoline), 2,2'-bis(4
-butyl-2-oxazoline), 2,2'bis(4
-hexyl-2-oxazoline), 2,2'-bis(4-phenyl-2-oxazoline), 2,2'-bis(4-cyclohexyl-2-oxazoline),
2,2'-bis(4-benzyl-2-oxazoline), 2,2'-p-phenylenebis(2-oxazoline), 2,2'-m-phenylenebis(2-oxazoline), 2,2'-o - Phenylembis (2
-oxazoline), 2,2'-p-phenylenebis(4-methyl-2-oxazoline), 2,2'-p-
Phenylenebis(4,4-dimethyl-2-oxazoline), 2,2'-m-phenylenebis(4-methyl-2-oxazoline), 2,2'-m-phenylenebis(4,4-dimethyl-2-oxazoline) ,2,2'-ethylenebis(2-oxazoline),2,2'-tetramethylenebis(2-oxazoline),2,2'-hexamethylenebis(2-oxazoline),2,2'-octamethylenebis (2
-oxazoline), 2,2'-decamethylenebis(2-oxazoline), 2,2'-ethylenebis(4
-Methyl-2-oxazoline), 2,2'-tetramethylenebis(4,4-dimethyl-2-oxazoline),2,2'-9,9'-diphenoxyethanebis(2-oxazoline),2 , 2'-cyclohexylenebis(2-oxazoline), 2,2'-diphenylenebis(2-oxazoline) and other bisoxazoline compounds; 2,2'-bis(5,6-dihydro-4H-1,3-oxazine) ), 2,2'-methylenebis(5,6-dihydro-4H-1,3-oxazine),2,2'-ethylenebis(5,6-dihydro-4H-1,3-oxazine),2,2 '-Flopylene bis (5,6-dihydro-4H-1,3-oxazine), 2,2'-butylene bis (5,6-dihydro-4H-1,3-oxazine), 2,2'-hexamethylene bis ( 5,6-dihydro-4H-
1,3-oxazine), 2,2'-p-phenylenebis(5,6-dihydro4H-1,3-oxazine),2,2'-m-phenylenebis(5,6-
dihydro4H-1,3-oxazine),2,2'-
Naphthylene bis(5,6-dihydro-4H-1,
3-oxazine), 2,2'-p,p'-diphenylenebis(5,6-dihydro-4H-1,3-oxazine), and the like. Among these compounds, 2,2'-bis(2-oxazoline), 2,2'-bis(5,6-dihydro-
4H-1,3-oxazine) is preferred. These compounds can be easily synthesized by a method of ring-closing the corresponding bisamide alcohol with a dehydrating agent such as concentrated sulfuric acid or thionyl chloride, or by a method of ring-closing the corresponding bisamide halide with an alkali. The method is not limited, and other methods can be used as appropriate. Since such a compound has extremely high reactivity with the -COOH group, by blending it into the above-mentioned saturated polyester (A), it reacts with the terminal carboxyl group of the saturated polyester in the melt or solid state, and efficiently converts the polyester into polyester. It is possible to increase the degree of polymerization and reduce the amount of terminal carboxyl groups. In particular, it is well known to those skilled in the art that a self-supporting preform is obtained by filling a mold with saturated polyester powder in advance and pressurizing the mold, and then heating it to obtain a molded product. In the case of the present invention, in which a molded article of saturated polyester is produced by a powder molding method, a specific amount of the above compound (B) is blended into the saturated polyester to prevent the polymerization of the saturated polyester during the molding process. The amount of terminal carboxyl groups can be increased or the amount of terminal carboxyl groups can be decreased. The molded product thus obtained has much improved mechanical strength and heat-and-moisture resistance compared to a molded product that does not contain compound (B). The compounding amount of the compound (B) is 0.01% by weight to 10% by weight based on the saturated polyester (A).
Weight%. If the amount is less than 0.01% by weight, the desired effect of the present invention will not be significantly exhibited;
If it exceeds % by weight, no further effect can be expected. A more preferable usage amount is 0.02% by weight to 5% by weight.
Weight%. The compound (B) can be blended into the saturated polyester (A) at any stage before obtaining the preform. For example, a method in which saturated polyester (A) and compound (B) are uniformly mixed in a molten state, and then the mixture is ground into powder: a solvent that can dissolve both saturated polyester (A) and compound (B); A method of producing a powder by removing the solvent from a mixture of solutions in which the saturated polyester (A) and the compound (B) are dissolved simultaneously or separately in two or more mutually compatible solvents: Method for preparing a powder blend by mixing powder of compound (B) with powder of saturated polyester (A) prepared in advance: Compound (B) is dissolved in powder of saturated polyester (A) prepared in advance. Products manufactured by a method such as contacting a solution in which compound (B) is dissolved in advance with a solvent that does not dissolve polyester (A) and then removing the solvent adhering to the surface of the powder to form a powder, etc. It can be used for powder molding as a suitable saturated polyester molding powder in the invention. The saturated polyester molding powder used in the present invention can be obtained by a known plastic powdering method. For example, there are reprecipitation methods in which the resin is dissolved in a soluble solvent and then added to a non-solvent; cutting and pulverization methods in which the resin is finely pulverized with a rotating metal blade; and impact pulverization methods in which the resin is pulverized by collision at high speed. Both are applicable. The size of the polyester powder is not particularly limited, but the powder that can be molded under uniform pressure during preforming will reduce the residual strain of the molded product and will be able to form polyester (A) in the process of heating the preform. Compound (B)
It is desirable to have a small particle size because it is advantageous for carrying out the reaction efficiently.
It is desirable to use powder that has been sieved through a sieve, preferably 20 mesh (JIS sieve) or more, more preferably 30 mesh or more. The molding powder thus obtained is filled into a mold and then press-molded to form a preform. The pressure applied in this case cannot be specified unconditionally because it depends on the type of saturated polyester and the shape of the molded product, but at least the preform has self-supporting properties at the stage when the preform is obtained. It is essential to have one. Here, self-supporting means that the shape of the preform is completely maintained against changes in operations and conditions from the time the preform is removed from the mold until the heat treatment in the next step is completed. means that it has been In order to use fine powder and to ensure that the preform has self-retention properties, it is sometimes effective to heat the mold to a temperature lower than the melting point of the molding powder and apply pressure. The self-supporting preform thus obtained is transferred to, for example, a heating furnace and heat-treated for a predetermined period of time at a temperature lower than the melting point of the saturated polyester, thereby completing the molding. On this occasion,
By maintaining the inside of the heating furnace under an inert gas atmosphere, for example under a nitrogen gas atmosphere, discoloration, oxidative deterioration, etc. of the molded product during the heat treatment stage can be significantly suppressed. Moreover, by changing the heat treatment temperature stepwise from a low temperature to a high temperature, a molded article with less distortion can be obtained. These temperature conditions can be selected based on the conditions normally used by those skilled in the art, and these conditions will of course vary depending on the type of saturated polyester to be molded. In the present invention, pigments and other additives may be added to the polyester resin composition in the desired amount. For example, ultraviolet absorbers, heat stabilizers,
One or more types of flame retardants, lubricants, nucleating agents, mold release agents, antistatic agents, etc. can be added. Furthermore, finely divided metals, metal oxides, minerals, abrasive materials such as silicon carbide and diamond, graphite, glass spheres, molybdenum disulfide, cryolite, boron nitride, iron sulfide, clay, mica, vermiculite, kaolin. You may add one or more of the following. Furthermore, one or more other thermoplastic resins such as polytetrafluoroethylene, polyphenylene oxide, polyphenylene sulfoxide, polyorganosiloxane, polysulfone, polyamide, polycarbonate, etc. may be added. Furthermore, fibrous substances such as glass fibers, carbon fibers, potassium titanate fibers, gypsum fibers, and asbestos may be added. When a polyester made from glycols is used as the saturated polyester in the present invention, it is more effective to use one or more compounds selected from the following general formulas () and () in combination. This is preferable because the object of the present invention can be achieved. [However, G and X' are divalent organic groups, and

The ring structure of [Formula] is a 5-membered ring or a 6-membered ring. l is 0 or 1. R is a monovalent organic group, and A is a tetravalent aromatic group. ] Examples of the compound represented by the general formula () include the following compounds. 2,2′-bis(5(4H)-oxazolone),
2,2'-methylenebis(5-(4H)-oxazolone), 2,2'-p-phenylenebis(5(4H)
-oxazolone), 2,2'-p-phenylene (4
-Methyl-5(4H)-oxazolone),2,2'-
p-phenylene (4,4-dimethyl-5(4H)
-oxazolone), 2,2'-m-phenylenebis(4,4-dimethyl-5(4H)-oxazolone), 2,2'-bis(3,1-benzoxazin-4-one), 2,2' -Ethylene bis(3,1-
benzoxazine-4-one), 2,2'-p-phenylenebis(3,1-benzoxazine-4-
on) etc. Further, as the compound represented by the general formula (), the following compounds can be exemplified. 2,8-dimethyl-4H,6H-benzo[1,2
-d:5,4-d']bis-[1,3]-oxazine-4,6-dione,6,6'-bis(2-methyl-4H-3,1-benzoxazin-4-one) ，
6,6′-methylenebis(2-methyl-4H-3,
1-benzoxazin-4-one), 6,6′-methylenebis(2-phenyl-4H-3,1-benzoxazin-4-one), etc. When such a compound is used in combination, the amount used is preferably 10% by weight or less, more preferably 0.02% to 5% by weight, based on the saturated polyester. The present invention will be described in detail below with reference to Examples. In addition, all "parts" in the examples mean "parts by weight." The amount of terminal carboxyl groups is the value obtained by dissolving the polymer in a mixed solution of benzyl alcohol and chloroform (1/1 volume ratio) and titrating and quantifying the solution using benzyl alcohol caustic soda and using phenol red as an indicator. . Furthermore, the intrinsic viscosity is a value measured in orthochlorophenol at 35°C. Examples 1 to 4 and Comparative Examples 1 to 2 Polyethylene terephthalate or polybutylene phthalate powder (passed through 35 meshes) and 2.
2′-bis(2-oxazoline) powder (passed through 35 meshes) was mixed in the proportions shown in Table 1, and the resulting mixed powder was heated to 100°C in a mold (inner cavity dimensions: 170×25× 70mm) and then
A pressure of 1200 Kg/cm ² was applied and kept under pressure for 5 minutes. The dimensions of the preform thus obtained are 170×
They were 25 x 3 tons and were self-supporting. Next, this preform was placed in a heating furnace previously maintained in a nitrogen atmosphere, and heat treated at 210° C. for 2 hours. The tensile strength (ASTM D-638
Table 1 shows the results of measuring the bending strength (based on ASTM D-790). The results show that molded products obtained by blending 2,2'-bis(2-oxazoline) have a lower terminal carboxyl group equivalent, an increased intrinsic viscosity, and mechanical strength compared to those without blending 2,2'-bis(2-oxazoline). It can be seen that the value becomes higher.

[Table] Example 5 100 parts of polyethylene terephthalate (intrinsic viscosity: 0.71) dried in a hot air dryer at 140°C for 5 hours and 2,2'-bis(5,6-dihydro 4H-1,
3-Oxazine) in a V-type blender and mix for 5 minutes.
Using a single screw extruder, the cylinder temperature is 270℃,
It was melt-extruded under the conditions of an average residence time of 2 minutes, and the thread having a diameter of about 3 mm discharged from the die was cooled and then cut to obtain pellets. Further, the pellets were pulverized using an impact pulverizer to obtain a powder that could pass through a 35 mesh (JIS) sieve. After uniformly mixing 10 parts of the powder thus obtained and 90 parts of polybutylene terephthalate powder (passed through a 35-mesh sieve; intrinsic viscosity 0.89) prepared in advance, the powder was mixed under the same conditions as in Example 1. After molding, the molded body was heat treated at 200° C. for 2 hours. The properties of the molded product thus obtained are as follows. Tensile strength 420 Kg/cm ² Bending strength 670 Kg/cm ² Intrinsic viscosity 1.06 Example 6, Comparative Example 3 Using diphenyl terephthalate/diphenyl isophthalate (7:3 molar ratio) and bisphenol A, the melt weight was The legally obtained polyarylate is crushed, passed through a 35 mesh sieve, and the intrinsic viscosity
A powder of 0.60 was obtained. 10 parts of this powder and the 2,2′- obtained in Example 5
After uniformly mixing with 10 parts of polyethylene terephthalate powder containing bis(5,6-dihydro-4H-1,3-oxazine), a preform was formed under the same conditions as in Example 1, and then the obtained preform The body was heated at 100℃ for 30 minutes in a heating furnace maintained in a nitrogen atmosphere.
Heat treatment was performed at 130°C for 2 hours, and then at 160°C for 4 hours. The properties of the heat-treated molded article thus obtained are as follows. Tensile strength 680Kg/ ^cm2Bending strength 820Kg/ ^cm2On the other hand, 2,2'-bis(5,6-dihydro
Using polyarylate alone without mixing polyethylene terephthalate powder containing 4H-1,3-oxazine), preforming and heat treatment were performed under the same conditions as above, and the resulting molded product had a tensile strength of 240 Kg/cm. ^2Bending strength is 290Kg/ ^cm2 . Example 7 A copolymerized polyarylate was obtained by an interfacial polymerization method from a methylene chloride solution of a mixed acid chloride having a molar ratio of terephthalic acid dichloride/isophthalic acid dichloride of 1:1 and an alkaline aqueous solution of bisphenol A. The intrinsic viscosity of this polyarylate was 0.65. Next, 100 parts of this polyarylate powder (passed through a 35-mesh sieve) was added to a 5% methanol solution of 2,2'-bis(2-oxazoline) prepared in advance.
Mix evenly with 20 parts of polyarylate powder, thoroughly wet the surface of the polyarylate powder with methanol solution, and then add 80 parts of polyarylate powder.
Methanol was removed in a hot air dryer at °C. 2,2′- of the polyarylate thus obtained
The bis(2-oxazoline) treated powder was filled into the mold used in Example 1 and cold compressed under a pressure of 2000 kg/cm ² to obtain a preform. Next, this preform was transferred to a heating furnace maintained in a nitrogen atmosphere, and the temperature of the heating furnace was raised under the following conditions for heat treatment. That is, room temperature → 80°C for 30 minutes, 80°C → 130°C for 1 hour, 130°C → 160°C for 1 hour, and 160°C for 4 hours. The properties of the molded product heat-treated in this manner are as follows. Tensile strength 710Kg/ ^cm2 Bending strength 830Kg/ ^cm2 Intrinsic viscosity 0.82

Claims (1)

[Claims] 1 0.01 to 10% by weight of the following general formula based on saturated polyester (A) [However, in the formula, D is a divalent organic group, and n is 0 or 1. Among divalent organic groups, X is a group in which the ring and groove structure of [Formula] forms a 5-membered ring or a 6-membered ring. ] A powder of a polyester resin composition prepared by blending the compound (B) represented by is pressure-molded in a mold to obtain a preform, and then the preform is heated above the melting point of the saturated polyester (A). A method for molding polyester resin characterized by exposure to low temperatures.