JPH1149942A - Polyester resin composition for decorative steel sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition which is laminated on a surface-treated steel sheet directly or via an adhesive and which is excellent in transparency, processability, chemical resistance, stain resistance and impact resistance by blending an ethylene terephthalate-based polyester with a polycarbonate resin having a weight-average molecular weight within a specific range in a specific ratio. SOLUTION: An ethylene terephthalate-based polyester and a polycarbonate resin having a weight-average molecular weight in the range of 20,000-30,000 are blended in a weight ratio of 70:30-95:5. The limiting viscosity of the polyester resin is preferably 0.6-1.0 dl/g or above. An antioxidant is preferably added to the composition. The antioxidant is preferably a hindered phenol-based organic compound. The antioxidant is preferably added in a polymerization process of the polyester resin and/or the polycarbonate resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to transparency, processability,
The present invention relates to a polyester resin composition for decorative steel sheet having excellent chemical resistance, stain resistance, and impact resistance.

[0002]

2. Description of the Related Art In recent years, as a resin-coated decorative steel sheet, a steel sheet coated with a film of polyvinyl chloride, polyolefin, polyester or the like has been widely used as a decorative steel sheet for home appliances and interior / exterior building materials.

[0003] However, the polyvinyl chloride-coated steel sheet deteriorates the working environment due to plasticizer, chlorine and the like generated by heating at the time of production, and causes air pollution during the combustion treatment. Further, the polyolefin-coated steel sheet is a relatively environmentally friendly material, but has a drawback of poor chemical resistance and stain resistance.

On the other hand, polyesters represented by polyethylene terephthalate (hereinafter referred to as PET) have been widely used as fibers, films and sheets because of their excellent mechanical properties, heat resistance and chemical resistance. However, most of the steel sheets coated with a polyester film have a stretched polyester film coated on the steel sheet via an adhesive layer.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a polyester for a decorative steel sheet having excellent transparency, workability, chemical resistance, stain resistance and impact resistance. It is to provide a resin composition.

[0006] The decorative steel sheet using the resin composition of the present invention comprises:
It is a decorative steel sheet obtained by laminating a transparent resin composition layer of the present invention on the surface-treated steel sheet directly or via an adhesive layer. A colored layer may be used between the steel plate and the adhesive layer or on the adhesive layer, and the thickness of the resin composition layer is 10 to 50.
0 μm.

[0007]

An object of the present invention is to provide a polyester resin mainly composed of ethylene terephthalate and a polycarbonate resin, wherein a weight ratio of the polyester resin and the polycarbonate resin is 70:30 to 95: 5. Polyester resin 8
0 to 95 parts by weight, and a weight average molecular weight of 20,000
It is attained by a polyester resin composition for decorative steel sheets, which is characterized by having a molecular weight of from 30,000. The decorative steel sheet may have any irregularities on the resin surface as needed.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION

[Polyester Resin] The polyester resin used in the resin composition of the present invention is a polyester mainly composed of ethylene terephthalate, and may be a homopolymer, but a copolymer component may be used according to the purpose.

Specific examples of the compounds that can be used include adipic acid, oxalic acid, malonic acid, succinic acid, azelaic acid, sebacic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, cyclohexanedicarboxylic acid, and dimer acid. And diol components such as butanediol, neopentyl glycol, propylene glycol, hexamethylene glycol, 1,4-cyclohexanedimethanol, polyalkylene glycol, and a diethoxy compound of bisphenol A or bisphenol S. These alone are 2
More than one species can be used.

The polyester resin used in the resin composition of the present invention preferably has an intrinsic viscosity of 0.6 to 1.0 dl / g or more, more preferably 0.7 to 0.9 dl / g.
Is more preferable from the viewpoint of the impact resistance of the decorative steel sheet obtained. It is difficult to produce a polyester resin having an intrinsic viscosity exceeding 1.0 dl / g.

[Polycarbonate Resin] The polycarbonate resin of the present invention is a polymer or copolymer comprising dihydric phenol and phosgene or a phosgene precursor. For example, an aromatic polycarbonate resin which can be produced from a dihydroxydiarylalkane such as bisphenol A and phosgene or a carbonic acid diester is exemplified.

The average molecular weight by weight of the polycarbonate resin used in the present invention is preferably from 20,000 to 30,000, and more preferably from 20,000 to 25,000. When the weight average molecular weight is within the above range, the resulting decorative steel sheet has improved impact resistance and excellent translucency.

The weight ratio between the polyester resin and the polycarbonate resin is as follows: polyester resin: 80 to
It is 5 to 20 parts by weight with respect to 95 parts by weight. It is necessary that polycarbonate resin = 70: 30 to 95: 5. If the amount of polycarbonate is less than the lower limit of the resin, the impact resistance of the decorative steel sheet is reduced.If the ratio of the polycarbonate resin exceeds the upper limit, the compatibility with the polyester resin is deteriorated, and the transparency is significantly reduced. 20 parts by weight.

The resin composition of the present invention is obtained, for example, by mixing a dried polyester resin and a polycarbonate resin in a chip state with a tumbler or the like, and melt-mixing them by using a conventional single-screw or twin-screw extruder. Any of resin mixed in a chip state may be used.

It is preferable to add an antioxidant to the resin composition of the present invention in order to prevent thermal deterioration of the resin composition during heat treatment and maintain impact resistance. As a useful antioxidant, a hindered phenol organic compound is preferable. The antioxidant may be added at any stage in the production process of the resin composition. However, in order to uniformly disperse the antioxidant in the polyester composition, the antioxidant should be added in the polymerization process of the polyester resin and / or the polycarbonate resin. Is preferred.

[0016]

The steel sheet coated with the polyester resin composition of the present invention has excellent transparency, workability, chemical resistance, stain resistance, and impact resistance, and is suitable as a decorative steel sheet for home appliances and interior / exterior building materials. Can be used.

[0017]

The present invention will be described below in detail with reference to examples. The measurement and evaluation of each physical property followed the following methods.

(1) Melting Point (Tm) The polyester resin was measured at a heating rate of 10 ° C./min by a differential scanning calorimeter (DSC-7, manufactured by Perkin Elmer).

(2) Intrinsic viscosity (IV) The polyester resin is phenol / tetrachloroethane =
It was dissolved in a 60/40 (weight ratio) mixture and measured at 20 ° C.

(3) Weight average molecular weight (Mw) A polycarbonate resin was dissolved in O-dichlorobenzene, and the measurement was carried out by a GPC method (GPC200 manufactured by Waters) at a column temperature of 130 ° C. and a flow rate of 1 ml / min.

(4) Film Transparency A polyester resin composition obtained by blending a polyester resin and a polycarbonate resin is dried under reduced pressure at 130 ° C. for 8 hours to reduce the water content to 100 ppm or less. 100μm thickness
Was formed. The haze of this film is JIS
It was measured according to K 7105 and converted to a thickness of 1 mm for evaluation. ：: less than 6% haze △: 6% or more and less than 10% ×: 10% or more

(5) Impact resistance The above-mentioned film is heated to 180 ° C. and has a thickness of 0.5 mm.
And passing it between the cooling roll and the nip rubber roll at a speed of 2 m / min for temporary lamination. Further, the resin-coated plate was preheated to 210 ° C., and a linear pressure of 100 kg / cm and a pressure of 3 m / mi were applied between mirror-cooled rolls at 30 ° C.
Pass at a speed of n. Using this laminated resin-coated steel sheet, leave it in water at 30 ° C. for 2 weeks, and then use a DuPont impact test (JIS K 5400) to apply a 500 g weight on the surface opposite to the surface coated with resin from a height of 50 cm. And cracks on the resin-coated surface were observed. ○: No visual cracking ×: Visual cracking

(6) Chemical resistance (stain resistance) An oil-based marker was applied to the resin-coated surface of the decorative steel sheet, left for 24 hours, and then wiped off with a 20% aqueous ethanol solution. Evaluation was made based on the presence or absence of stains on the decorative steel sheet after wiping. ○: Dirt does not remain △: Dirt remains to some extent ×: Dirt is severe

Examples 1 to 3 and Comparative Examples 1 to 3 Production of Film Polyester resin having the composition shown in Table 1 and polycarbonate resin poly-4,4'dioxydiphenyl-2 obtained from bisphenol A and phosgene , 2 '
-Using a propane carbonate, the polyester resin composition blended in the ratio of Table 1 was dried under reduced pressure at 130 ° C. for 8 hours to reduce the water content to 100 ppm or less, and the width was 40 cm.
To a small extruder with a T die
m was formed. The temperature of the cylinder of the extruder was 280 ° C., the temperature of the T-die was 280 ° C., and the temperature of the cooling roll was 40 ° C. The obtained films (F-1 to F-
The haze of 6) was measured, and the transparency was evaluated. Table 1 shows the results
Shown in

[0025]

[Table 1]

Production of resin-coated steel sheet The above-mentioned film was heated to 180 ° C. and had a thickness of 0.5 mm.
And passing it between the cooling roll and the nip rubber roll at a speed of 2 m / min for temporary lamination. Further, the resin-coated plate was preheated to 210 ° C., and a linear pressure of 100 kg / cm and a pressure of 3 m / mi were applied between mirror-cooled rolls at 30 ° C.
The resin-coated steel sheet was obtained at a speed of n. The stain resistance and impact resistance of the obtained decorative steel sheet were evaluated, and the results are shown in Table 2.

[0027]

[Table 2]

Comparative Examples 4 and 5 The same experiments and evaluations as in the Examples were conducted except that a high-density polyethylene resin (Comparative Example 4) and a polypropylene resin (Comparative Example 5) were used instead of the resin composition of the present invention. went. Table 1 shows the results of evaluating the haze and transparency of the films (F-7, F-8), and Table 2 shows the results of evaluating the impact resistance and stain resistance of the decorative steel sheet.

From the results shown in Table 2, it can be seen that the resin composition of the present invention exhibits performance suitable for decorative steel sheets.

Examples 4 to 11 The same experiments and evaluations as in the previous examples were carried out using polyester resins having the compositions shown in Table 3 and polycarbonate resins the same as those used in the previous examples. Table 3 shows the results of evaluating the haze and transparency of the obtained films (F-9 to F-16), and Table 4 shows the results of evaluating the stain resistance and impact resistance of the decorative steel sheet.

[0031]

[Table 3]

[0032]

[Table 4]

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁶ Identification code FI (C08L 67/02 69:00)

Claims (1)

[Claims] 1. A polyester resin mainly composed of ethylene terephthalate, which is composed of a polyester resin composed mainly of ethylene terephthalate and a polycarbonate resin, wherein the weight ratio of the polyester resin to the polycarbonate resin is 70:30 to 95: 5, and 80 to 95% by weight of a polyester resin composed mainly of ethylene terephthalate. Parts, and a weight average molecular weight of 20,000 to 30,000.