JP2003003000A - Polyester resin composition and method for producing polyester resin foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition for producing a polyester resin foam having uniform and fine cells, and an excellent appearance, and to provide a method for producing the polyester resin foam. SOLUTION: This polyester resin composition comprises 100 pts.wt. thermoplastic polyester resin, 0.1-20 pts.wt. acrylic processing aid having 500,000-5,000,000 average molecular weight, and 0.1-5 pts.wt. foaming agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester resin composition and a method for producing a polyester resin foam, and more particularly to a polyester resin composition having uniform and fine cells and excellent appearance characteristics. The present invention relates to a resin composition for producing a resin foam. The present invention also relates to a method of making a polyester-based resin foam.

[0002]

2. Description of the Related Art Thermoplastic polyester resins are used for fibers,
It is widely used for the production of hollow products such as films and bottles, but when it is used for foam molding, it is difficult to extrude and foam because uniform and fine bubbles cannot be formed and gas easily escapes. It was

Japanese Patent Publication No. 61-48409 discloses a method in which 0.1% of aromatic polyester is used as a standard before melt extrusion.
There is described a method for producing a polyester extruded foam characterized by incorporating from 3 to 3% by weight of a diglycidyl ester compound.

Japanese Patent Laid-Open No. 2-150434 discloses the production of a thermoplastic polyester resin foam in which a thermoplastic polyester resin is melted, the melt is mixed with a foaming agent, and the mixture is extruded under low pressure conditions and foam-molded. The method describes a method for producing a polyester-based resin foam, which comprises adding a compound having two or more acid anhydride groups in the molecule to a thermoplastic polyester-based resin.

Japanese Patent Publication No. 3-16977 discloses a thermoplastic polyester resin, and a polyfunctional glycidyl ester compound 0.03 to 2.5 mo with respect to the thermoplastic polyester resin.
1%, polyfunctional carboxylic acid anhydride 0.01 to 2 mol% with respect to the thermoplastic polyester resin, and boiling point at normal pressure 15
There is described a method for producing a thermoplastic polyester resin foam, which comprises mixing a foaming agent at 0 ° C. or lower to allow extrusion foaming.

Japanese Patent No. 2521854 discloses a polyester characterized in that a polyester having a molecular weight distribution of 5.0 to 21.0 is mixed with a foaming agent in an extruder and the melt is extruded and foamed under a low pressure. A method of making a foam is described.

[0007]

In the extrusion foaming of thermoplastic polyester, there is a problem that the melt viscosity of the thermoplastic polyester itself during extrusion is low and uniform and fine bubbles cannot be retained during extrusion foaming. In melt extrusion foaming, it is generally said that the viscosity characteristics of the molten polymer are important, the decrease in viscosity with temperature rise is low, and the foaming suitable viscosity range is preferably wide. That is, in the case of an amorphous polymer such as polystyrene, the decrease in viscosity with temperature rise is relatively gradual, so the foaming suitable viscosity range is wide, but in a crystalline polymer such as polyethylene terephthalate (PET), a sharp decrease in viscosity occurs. Therefore, the foaming suitable viscosity range is narrow.

The application of chemical cross-linking reaction is well known as a means for suppressing a rapid decrease in viscosity when a polymer is melted, and most of the above-mentioned prior arts use this means for extrusion foaming of a polyester resin. Is applied to. The last-cited prior art utilizes the increase in melt viscosity due to the branched chain structure of polyester for extrusion foaming.

Although the former chemical crosslinking means has the advantage that it can be applied to various polyester raw materials,
It is difficult to set and manage reaction conditions for obtaining an appropriate melt viscosity, and even a slight change in the conditions causes a large change in melt viscosity, and it cannot be said that the production of a satisfactory foam is industrially successful. On the other hand, the latter use of a polyester raw material having a wide molecular weight distribution has an advantage that complicated process control is not required, but has a disadvantage that the polyester raw material to be used is limited.

Another problem that occurs when producing an extruded foam from a thermoplastic polyester resin is that the melting temperature of the polyester is quite high, and the polyester is easily hydrolyzed in the presence of water and has a molecular weight of Is likely to occur. Therefore, in the production of a polyester molded article, using a hopper dryer, prior to the melt-kneading of the polyester, the polyester is sufficiently dried, in chemical foaming,
There is also a problem that water is generated at the same time due to decomposition of the foaming agent, and the melt viscosity required for foaming cannot be secured due to hydrolysis of the polyester. Therefore, in the conventional method for producing an extruded foam of a polyester resin, physical foaming using a gas or a volatile substance as a foaming agent is generally adopted,
Physical foaming has problems that it requires a large scale of equipment, causes post-shrinkage after molding, and that fine cells cannot be obtained.

Therefore, an object of the present invention is to provide a resin composition for producing a polyester resin foam having uniform and fine cells and excellent in appearance characteristics, and a method for producing the polyester resin foam. There is. Another object of the present invention is to provide a polyester resin composition in which the polyester resin melt is maintained in a foaming suitable viscosity range during extrusion foaming. Still another object of the present invention is to provide a polyester resin composition capable of producing a polyester foam by chemical foaming.

[0012]

According to the present invention, a thermoplastic polyester resin and an acrylic resin having an average molecular weight of 500,000 to 5,000,000, preferably 2,000,000 to 4,000,000 per 100 parts by weight of the polyester resin are used. Auxiliary 0.1
A polyester resin composition comprising 20 parts by weight and 0.1 to 5 parts by weight of a foaming agent is provided. In the polyester resin composition of the present invention, 1. 1. The thermoplastic polyester is an ethylene terephthalate type polyester or a polyester containing cyclohexanedimethanol as a glycol component; 2. The foaming agent is a chemical foaming agent, 3. further containing an inorganic filler and / or a cellulosic filler; It is preferable to contain the inorganic filler and / or the cellulosic filler in an amount of 1 to 900 parts by weight, preferably 5 to 100 parts by weight. According to the present invention, the polyester resin composition is further kneaded by an extruder with a vent and extruded under a low pressure to foam at a foaming ratio of 1.5 to 5.0. A method of manufacturing a body is provided.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The resin composition of the present invention comprises a thermoplastic polyester resin and an acrylic processing aid having an average molecular weight of 500,000 to 5,000,000, preferably 2,000,000 to 4,000,000 per 100 parts by weight of the polyester resin. Agent 0.1-2
The feature is that 0 parts by weight and 0.1 to 5 parts by weight of a foaming agent are combined. Due to this feature, in the resin composition of the present invention, the melt viscosity of the resin is increased, and extrusion foam molding is possible.

Generally, in the melt-foam molding of a resin, the foam molding is carried out through a process of dispersing a gas in the resin and a process of growing bubbles in the resin. In the resin composition used in the present invention, an acrylic resin is used. Since the auxiliary agent and the foaming agent are contained in a limited amount ratio, the melt viscosity of the resin composition is maintained in a viscosity range suitable for extrusion foaming, and gas dispersion in the resin and growth of bubbles in the resin are maintained. It is possible to produce a polyester-based resin foam that smoothly progresses, foams effectively, has uniform and fine bubbles, and has excellent appearance characteristics.

Further, in extrusion foaming of a polyester resin, the use of a chemical foaming agent is caused by hydrolysis of the polyester by water produced at the time of decomposition and decrease in viscosity due to the hydrolysis.
Although thought to be difficult, according to the present invention, extrusion foaming using a chemical foaming agent can be performed by maintaining a melt viscosity in an appropriate range by adding a specific amount of an acrylic processing aid. It will be possible. Also, by using a chemical foaming agent,
Improves workability of extrusion foaming and simplifies equipment,
It is possible to improve the productivity of the polyester foam molded article and reduce its cost.

The polyester resin composition of the present invention further contains an inorganic filler and / or a cellulosic filler, and in particular, the inorganic filler and / or the cellulosic filler is contained in an amount of 1 per 100 parts by weight of the polyester resin.
It is preferable to contain it in an amount of ˜900 parts by weight, preferably 5 to 100 parts by weight. By containing the above filler in the resin composition, the filler becomes a nucleus during the foaming of the chemical foaming agent, and a fine and uniform foam cell structure is obtained, and the slipperiness with a metal surface such as a die during extrusion foaming. It is possible to produce a foam having improved appearance characteristics and surface characteristics. Furthermore, by containing a filler, the manufacturing cost of the foam can be reduced, and the physical properties and chemical properties of the foam can be improved.

In the present invention, a composition containing a thermoplastic polyester, an acrylic processing aid and a chemical foaming agent or a filler is supplied to an extruder, melt-kneaded and then extruded to produce a polyester resin foam. To do.
At this time, it is preferable that the polyester resin composition is kneaded by an extruder with a vent mechanism and extruded under a low pressure. By using an extruder with a vent for melt-kneading the resin composition, degassing during kneading of the resin composition is effectively performed, hydrolysis of the polyester resin is suppressed, and more uniform and fine bubbles are formed. It becomes possible to produce a polyester resin foam having the above and excellent appearance characteristics.

The polyester resin composition of the present invention is preferably foamed so that the expansion ratio (volume basis) is 1.5 to 5.0 times. When the expansion ratio is less than 1.5, the lightness, cushioning, and
The insulating property against sound and heat becomes insufficient as compared with the case where it is within the above range, while the foam cells become coarse so that the expansion ratio becomes 5.0 times, and compared with the case where it is within the above range. ,
The rigidity is lowered and the permanent set against deformation is increased, which is not preferable.

[Thermoplastic Polyester] The thermoplastic polyester resin used in the present invention is a homopolyester or a copolyester derived from a dibasic acid mainly containing terephthalic acid and a diol mainly containing ethylene glycol. Good.

Dibasic acids other than terephthalic acid include isophthalic acid, P-β-oxyethoxybenzoic acid, naphthalene-2,6-dicarboxylic acid and diphenoxyethane-
4,4'-dicarboxylic acid, 5-sodium sulfoisophthalic acid, hexahydroterephthalic acid, adipic acid, sebacic acid and the like can be mentioned.

As diol components other than ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexylene glycol, diethylene glycol, triethylene glycol, cyclohexanedimethanol, spiroglycol, bisphenol A. Examples thereof include glycol components such as ethylene oxide adducts.

The homopolyester or copolyester should have a molecular weight in the film forming range,
The intrinsic viscosity [IV] measured using a phenol / tetrachloroethane mixed solvent as a solvent is 0.5 to 1.
5, preferably in the range of 0.6 to 1.5.

In a typical example of the present invention, polyethylene terephthalate (PET) is used because of its ready availability. As this polyethylene terephthalate, it is possible to use either a usual melt polymerization method or a solid phase polymerization method. In another example, recycled PET resin can also be used. Recycled PE
T-resin is used after being used as a container such as a bottle and then recovered and subjected to a regenerating treatment such as washing. Its intrinsic viscosity [IV] is lower than that of virgin PET. Can be used alone or in combination with Virgin PET.

In another embodiment of the invention, other thermoplastic polyesters having a relatively high melt viscosity as compared to polyethylene terephthalate can be used. For example, cyclohexanedimethanol (CHD as part of the glycol component
An ethylene terephthalate-based copolyester resin containing M) can be used. This glycol modified ethylene terephthalate copolyester resin (PET-G)
Is characterized by being non-crystalline, having a melting temperature considerably lower than that of polyethylene terephthalate, and having a high melt viscosity. This PET-G is commercially available from Eastman under the trade name of Provista and is easily available.

Other polyester resins having a high melt viscosity can be used. That is, a thermoplastic polyester having a branched chain structure described in Japanese Patent No. 2521854, that is, a polybasic acid component such as trimellitic acid or pyromellitic acid as an acid component other than terephthalic acid, or a component other than ethylene glycol As the alcohol component, a polyester derived from a polyhydric alcohol component such as pentaerythritol, trimethylolpropane, dipentaerythritol, and glycerin can also be used.

[Acrylic Processing Aid] In the present invention, the average molecular weight (Mw) is 500,000 to 5,000,000, especially 20.
0,000 to 4 million acrylic resin-based processing aids are used. This acrylic resin is polymethylmethacrylate (P
MMA) is preferable from the viewpoint of heat resistance and physical properties of the foam, but it is a copolymer mainly composed of methyl methacrylate and containing a small amount of other monomer components as a comonomer. Good.

Examples of such monomers other than methyl methacrylate include methyl acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate,
N-butyl (meth) acrylate, isobutyl (meth) acrylate, n-amyl (meth) acrylate, isoamyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (Meta)
Examples thereof include ester monomers such as n-octyl acrylate. However, the above-mentioned (meth) acrylic acid means acrylic acid or methacrylic acid. Further, it may contain a monomer other than acrylic type such as styrene, α-methylstyrene, vinyltoluene, acrylonitrile, methacrylonitrile and vinyl acetate. Furthermore, this polymer acrylic processing aid may contain a small amount of a functional group-containing monomer component, and as the functional group-containing monomer component, a carboxyl group, a salt group thereof, an amide group, Hydroxyl group,
It has an amino group, an epoxy group, a methylol group, and an etherified methylol group, and specifically includes the following. Ethylenically unsaturated carboxylic acid or its anhydride; acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, maleic anhydride, itaconic anhydride and the like. Amide group-containing monomer;
(Meth) acrylamide and the like. Hydroxyl group-containing monomer; vinyl alcohol, (meth) acrylic acid hydroxyethyl ester, (meth) acrylic acid hydroxypropyl ester, acrylic acid propylene glycol monoester, and the like.
Amino group-containing monomer; dimethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate, vinylpyridine, 2-vinyl-5-ethylpyridine, oxazolylethyl (meth) acrylate, (meth)
Hydroxyethyl aminoethyl acrylate, etc. Epoxy group-containing monomer; (meth) acrylic acid glycidyl ether, allyl glycidyl ether, butane monoxide, etc. Monomers having a methylol group and an etherified methylol group; dimethylol compounds of (meth) acrylamide, and their ether compounds such as ethyl ether compounds and butyl ether compounds. These functional group-containing monomers can be present in the acrylic resin in the form of a random copolymer, a graft copolymer or a block copolymer.

The polymeric acrylic processing aid used in the present invention has an amount within the above-mentioned range from the viewpoint of increasing the melt viscosity of the resin composition and improving the melt foaming moldability and the physical properties of the foam to be formed. It preferably has a molecular weight, and if it has a molecular weight in the above-mentioned range, it is possible to obtain the above-mentioned molded product having a foamed structure.

[Foaming Agent] As the foaming agent that can be blended, all of the chemical foaming agents that have hitherto been used in the production of foamed resin moldings of this type can be used. Typical examples include inorganic foaming agents such as sodium bicarbonate, sodium carbonate, ammonium bicarbonate, ammonium carbonate, ammonium nitrite; N, N'-dimethyl-N, N'-dinitroso terephthalamide, N, N '. -Nitroso compounds such as dinitroso, pentamethylene and tetramine; azo compounds such as azodicarbonamide, azodicarboxamide, azobisisobutyronitrile, azocyclohexylnitrile, azodiaminobenzene, barium and azodicarboxylate; benzenesulfonyl hydrazide, Sulfonyl hydrazide compounds such as toluenesulfonyl hydrazide, P, P'-oxybis (benzenesulfonyl hydrazide), diphenyl sulfone-3,3'-disulfonyl hydrazide;
Examples thereof include azide compounds such as calcium azide, 4,4′-diphenyldisulfonyl azide and p-toluenesulfonyl azide. Among them, nitroso compounds,
Azo compounds and azido compounds are preferably used.

If desired, a foaming aid may be used in combination with the foaming agent. The foaming aid is an additive that functions to lower the decomposition temperature of the foaming agent, promote decomposition, uniformize bubbles, and the like. As a foaming aid, citric acid, salicylic acid,
Examples thereof include organic acids such as phthalic acid and stearic acid; urea and its derivatives.

[Filler] The polyester-based expandable resin composition of the present invention may contain an inorganic filler and / or a cellulose-based filler. As the inorganic filler, alumina, attapal guide, kaolin, carbon black, graphite, finely divided silicic acid, calcium silicate, diatomaceous earth, magnesium oxide, magnesium hydroxide, aluminum hydroxide, slate powder, sericite, flint, calcium carbonate, talc. , Feldspar powder, molybdenum disulfide, barite, vermiculite, whiting, mica, wax stone clay, gypsum, silicon carbide, zircon,
Glass beads, shirasu balloon, asbestos, glass fiber, carbon fiber, rock wool, slag wool, boron squid, stainless steel fiber, titanium white, zinc white, red iron oxide, iron black, yellow iron oxide, titanium yellow, chromium oxide green, ultramarine blue, navy blue Etc.

On the other hand, examples of the cellulosic filler include cotton linter, wood pulp, crushed paper, and wood powder. For example, wood powder having a particle size of 100 mesh size or less (150 μm or less) is used, for example, powder of any wood such as softwood, hardwood, and lauan wood is used, and sawdust by-produced during sawing, Plane scraps or MDF,
Waste materials such as particle board and plywood can also be used after being pulverized by ball milling or the like.

[Resin Composition] In the present invention, the polyester-based expandable resin composition is thermoplastic polyester 1
0.1 to 20 parts by weight of acrylic processing aid per 100 parts by weight
Parts by weight, preferably 1 to 900 parts by weight, and a blowing agent in an amount of 0.1 to 5 parts by weight, preferably 5 to 100 parts by weight. When the amount of the acrylic processing aid is less than the above range, the effect of increasing the melt viscosity is insufficient, the foam moldability is deteriorated, and the surface condition of the foam is deteriorated as compared with the case where the amount is within the above range. . Further, when the amount of the acrylic processing aid exceeds the above range, the physical properties of the foamed product tend to deteriorate as compared with the case where the amount is within the above range.

If the amount of the foaming agent is below the above range,
The foaming ratio of the formed foam tends to be less than 1.5, which is not preferable for the reason described above. On the other hand, when the amount of the foaming agent exceeds the above range, the foaming ratio of the formed foam tends to exceed 5.0, which is also unfavorable for the reasons described above.

The polyester resin composition of the present invention preferably further contains an inorganic filler and / or a cellulosic filler, and the inorganic filler and / or the cellulosic filler is contained in an amount of 1 to 900 parts by weight per 100 parts by weight of the polyester resin. , And preferably in an amount of 5 to 100 parts by weight. When the content of the filler is less than the above range, the nucleating agent effect and the slipperiness imparting effect at the time of foaming tend to be insufficient, and when the content of the filler exceeds the above range, the extrusion foamability decreases, It is not preferable because the surface properties of the resulting foam are also deteriorated.

The expandable resin composition of the present invention contains a heat resistance stabilizer, a weather resistance stabilizer, an antioxidant, an antiaging agent, a light stabilizer,
A known resin compounding agent such as an ultraviolet absorber, an antistatic agent, a lubricant such as metal soap or wax, and a modifying resin or rubber can be compounded according to a known method.

For example, for the purpose of improving workability and moldability, fatty acid metal soaps such as barium stearate and magnesium stearate, and lubricants such as fatty acid amide, polyethylene wax and microcrystalline wax can be blended. Lubricants are 1 to 1 based on the above two components
It can be blended in an amount of 0% by weight. Further, in order to improve the wettability of the wood powder particles to the resin and to enhance the dispersibility in the resin, it is possible to use an acrylic-modified fluororesin, for example, an acrylic-modified polytetrafluoroethylene resin, as a compatibilizer. it can. These compatibilizers can be used in an amount of 0.1 to 20% by weight based on the above two components.

The expandable resin composition of the present invention is obtained by dry blending the above components at room temperature. The mixing order of each component is not particularly limited, and each component may be mixed simultaneously or sequentially. For example, it is possible to pre-mix the components excluding the foaming agent, add the foaming agent to the pre-mixture and continue the blending, or pre-mix the filler with the foaming agent or other auxiliary agent, It is also possible to add thermoplastics and processing aids to the mixture and continue blending. The dry blending can be performed using a device known per se, and for example, a Henschel mixer or various blenders can be used.

[Method for Producing Foam] According to the present invention, a polyester resin foam is produced by feeding the above resin composition to an extruder, melt-kneading, and then extruding. It is preferable that the polyester resin composition is kneaded by an extruder with a vent mechanism and extruded under a low pressure. By using a vented extruder for melt-kneading the resin composition, degassing during kneading of the resin composition is effectively performed,
By suppressing the hydrolysis of the polyester resin, it becomes possible to produce a polyester resin foam having more uniform and fine bubbles and having excellent appearance characteristics.

As the vent extruder, a vent extruder known per se, generally with an opening provided at about 2/3 of the total length of the cylinder for the purpose of removing volatile components (water in this case) generated in the cylinder, It is used that removes volatile components into the atmosphere or by suction with a vacuum pump. The removal of water in the vent extruder can be performed at any stage from the state where the resin composition is substantially solid and tight to the state where the resin composition is completely melted.

The dry-blended resin composition is supplied to the hopper of a vent extruder, and the composition is transported, melted, kneaded, and foamed. For the purpose of preventing moisture absorption or drying of the resin composition, the hopper is used. It is also possible to use a dryer or a nitrogen gas replacement hopper.

As the extruder, an extruder known per se equipped with a single screw or a twin screw is used. In the melt-foam extrusion molding of the present invention, the temperature of the resin (cylinder temperature) at the time of melt-kneading varies depending on the type and blending ratio of the polyester resin, but generally 200 to 2
It is preferably in the range of 80 ° C. The ratio (L / D) of the screw length to the diameter is not particularly limited, but is generally preferably in the range of 20 to 30.

As the molding die, any molding die can be used according to the shape of the molded product to be molded,
In the case of a modified cross-section molded product, a modified cross-section die having a corresponding cross-sectional shape is used. Of course, it is also possible to manufacture a tubular foam molded product using a ring die and a flat molded product using a T die. Generally, the temperature of the molding die should be in the range of 200 to 280 ° C.

In the present invention, the extruded molded article is
It can be in contact with a guide or sizing die to stabilize the size and shape.

The foamed resin molded article according to the present invention utilizes the above-mentioned characteristics to make various building materials such as flooring materials and floor finishing materials,
Wall material or wall finishing material, ceiling material or ceiling finishing material, threshold,
It is useful in fields such as window frames, sashes, and structural materials such as furniture and panel materials.

[0046]

The present invention will be further described in the following examples. The following examples are for purposes of illustration and the invention is not limited in any way.

The measurement and evaluation in the examples were carried out as follows. 1) Melt viscosity (drawdown property) The extruded product hangs down between the mold and the sizing die due to its own weight. At this time, the hanging distance of the extruded product from the straight line connecting the mold and the sizing die was defined as X (cm), and the evaluation was made according to the following criteria. Drawdown ◯: Drawdown is small (X <1) X: Drawdown is large (X ≧ 1) 2) Surface condition: The surface of the obtained molded product was observed and the surface condition was evaluated according to the following criteria. ○ The surface condition of the molded product is good. × The surface of the molded product is rough, and irregularities are generated.

Example 1 A foamable resin composition was prepared using the following resins. Polyester resin (PET-G) 100 parts by weight Acrylic processing aid 5 parts by weight (Kanebuchi Chemical Industry Co., Ltd.) Baking soda / citric acid foaming agent 0.8 parts by weight

The foamable resin composition shown above was dry blended (20 minutes) at room temperature, and a vent extruder (L / D =
25, melting zone temperature = 230 ° C.), melted and kneaded, extruded from a die, and extruded through a sizing die to produce a foamed molded sheet. The thickness of the foamed resin sheet was 10 mm, the inside of this sheet was finely and uniformly foamed, and the surface condition was good.
The results obtained are shown in Table 1.

[Example 2] An extruded product was produced in the same manner as in Example 1 except that the following foamable resin composition was used. Polyester resin (PET-G) 100 parts by weight Acrylic processing aid 7 parts by weight (Kanebuchi Chemical Industry Co., Ltd.) Baking soda / citric acid foaming agent 1.2 parts by weight Talc 5 parts by weight Results obtained It shows in Table 1.

[Example 3] An extruded product was produced in the same manner as in Example 1 except that the following foamable resin composition was used. Polyester resin (PET-G) 100 parts by weight Acrylic processing aid 5 parts by weight (Kanebuchi Chemical Industry Co., Ltd.) Baking soda / citric acid foaming agent 0.8 parts by weight Titanium oxide 5 parts by weight Results obtained Is shown in Table 1.

[Example 4] An extruded product was produced in the same manner as in Example 1 except that the following foamable resin composition was used and the temperature of the melting zone was 220 ° C. Polyester resin (PET-G) 100 parts by weight Acrylic processing aid 10 parts by weight (Kanefuchi Chemical Industry Co., Ltd.) Azodicarbonamide 1 part by weight Wood powder 100 parts by weight The results obtained are shown in Table 1.

Comparative Example 1 An extruded product was produced in the same manner as in Example 1 except that the following foamable resin composition was used. Polyester resin (PET-G) 100 parts by weight Baking soda / citric acid foaming agent 1.2 parts by weight Table 1 shows the obtained results.

Comparative Example 2 An extruded body was produced in the same manner as in Example 1 except that the following foamable resin composition was used. Polyester resin (PET-G) 100 parts by weight Azodicarbonamide 1 part by weight Wood flour 100 parts by weight The obtained results are shown in Table 1.

[0055]

[Table 1]

[0056]

According to the present invention, the thermoplastic polyester resin and the average molecular weight per 100 parts by weight of the polyester resin are from 500,000 to 5,000,000, preferably from 2,000,000.
0.1 to 20 parts by weight of 4 million acrylic processing aids,
By combining with a foaming agent 0.1 to 5 parts by weight,
During extrusion foaming, the polyester-based resin melt is maintained in the foaming suitable viscosity range, and as a result, a polyester-based resin foam having uniform and fine cells and excellent in appearance characteristics can be produced. Further, according to the present invention, it becomes possible to produce a polyester foam by chemical foaming,
This makes it possible to improve the workability of extrusion foaming, simplify the equipment, improve the productivity of the polyester foam molded article, and reduce the cost thereof. Furthermore,
According to the present invention, by containing an inorganic filler and / or a cellulosic filler in the resin composition, the filler becomes a nucleus during foaming of the chemical foaming agent, and a fine and uniform foam cell structure is obtained, and During extrusion foaming, the slipperiness with a metal surface such as a die is improved, and it becomes possible to manufacture a foam having improved appearance characteristics and surface characteristics. Further, it is preferable that the polyester resin composition is kneaded by an extruder with a vent mechanism and extruded under a low pressure. By using an extruder with a vent for melt-kneading the resin composition, degassing during kneading of the resin composition is effectively performed, hydrolysis of the polyester resin is suppressed, and more uniform and fine bubbles are formed. It becomes possible to produce a polyester resin foam having the above and excellent appearance characteristics.

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Claims (7)

[Claims] 1. A thermoplastic polyester resin, 0.1 to 20 parts by weight of an acrylic processing aid having an average molecular weight of 500,000 to 5,000,000, and a blowing agent of 0.1 to 5 parts by weight per 100 parts by weight of the polyester resin. And a polyester resin composition. 2. The polyester resin composition according to claim 1, wherein the thermoplastic polyester is ethylene terephthalate polyester. 3. The polyester resin composition according to claim 1, wherein the thermoplastic polyester is a polyester containing cyclohexanedimethanol as a glycol component. 4. The polyester resin composition according to claim 1, wherein the foaming agent is a chemical foaming agent. 5. The polyester resin composition according to claim 1, further comprising an inorganic filler and / or a cellulosic filler. 6. The polyester resin composition according to claim 5, which contains an inorganic filler and / or a cellulosic filler in an amount of 1 to 900 parts by weight. 7. A polyester resin composition according to claim 1, which is kneaded by an extruder with a vent and extruded under a low pressure to foam at a foaming ratio of 1.5 to 5.0. A method for producing a polyester resin foam, which comprises: