JPH0117495B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a polypropylene resin composition with improved transparency, and in particular to a polypropylene resin composition that prevents elution and escape of a clarifying agent into water or hot water and is useful for food containers and packaging materials, medical instruments, etc. Regarding the composition. As a method for improving the transparency of polypropylene-based resins, JP-A-53-117044 describes adding 1,3,2,4-di(methylbenzylidene) sorbitol (hereinafter simply referred to as sorbitol) to polypropylene or its copolymer.
It has been proposed to blend DMBS (abbreviated as DMBS) and heat-form it. On the other hand, it can be used as a chlorine scavenger in the catalyst residue of polypropylene resins, to improve the fluidity of the resins, to improve the releasability from molds, and as a dispersant for other additives and pigments. Generally, metal salts of higher fatty acids such as calcium stearate and zinc stearate are added as stabilizers or lubricants. However, DMBS, the above-mentioned clarifying agent, is used in polypropylene resins.
When a metal salt of a higher fatty acid as a lubricant or stabilizer is used in combination, the resulting polypropylene resin composition is resistant to water, hot water, or steam.
Since DMBS easily elutes or escapes, it not only causes health and safety problems especially in the fields of food containers and packaging materials and medical instruments, but also has the disadvantage of impairing the long-term sustainability of transparency. As a result of intensive studies to solve the above-mentioned problems of polypropylene resin compositions using DMBS, the present inventors discovered that a specific compound can be mixed into a mixture of polypropylene resin and DMBS, and the present invention I have come to propose this. That is, the present invention provides polypropylene resin, 1.
This is a polypropylene resin composition consisting of 3,2,4-di(methylbenzylidene)sorbitol and calcium stearyl lactate. The resin composition of the present invention does not contain the conventionally known metal salts of higher fatty acids, but only contains calcium lactate.
Elution or escape of DMBS from DMBS-containing products can be completely prevented. Furthermore, these compositions do not impair the moldability, fluidity, mold releasability, thermal stability, etc. of conventionally known products containing higher fatty acid metal salts. The polypropylene resin used in the present invention is a propylene homopolymer,
Alternatively, it is a copolymer of polypropylene having a propylene content of 70% by weight or more and one or more of ethylene, butene, pentene, vinyl acetate, vinyl chloride, etc., and a blend of these polymers. 1,3,2,4-di(methylbenzylidene) sorbitol used in the present invention is a condensate of tolualdehyde and sorbitol, and any known method for producing the same can be used without particular limitation. Calcium stearyl lactate used in the present invention has a polymerization degree of 2.
The main component is a calcium salt of an esterification product of lactic acid (2-lactyl lactic acid) and stearic acid (stearyl lactic acid), and is a mixture of this and a small amount of salts of related acids. The blending ratio of the above resin composition may be appropriately selected depending on the application, but in particular, polypropylene resin
It is preferable to mix 0.01 to 1 part by weight of DMBS and 0.01 to 1 part by weight of calcium stearyl lactate to 100 parts by weight, since the effects of the present invention are very clearly exhibited. The resin composition of the present invention may also contain antioxidants, antistatic agents, lubricants, dispersants, pigments, fluorescent agents, bactericides, light stabilizers, ultraviolet absorbers, metal deactivators, and Additives such as photodegradation accelerators can also be blended within a range that does not significantly reduce the effects of the present invention. A desired molded article can be obtained from the resin composition of the present invention by kneading and molding using conventional methods. The present invention will be specifically explained below based on Examples, but the present invention is not particularly limited to the Examples below. The measurement methods used in the following Examples and Comparative Examples are shown below. (1) Haze: Conforms to ASTM D1003-61 (measured on 3mm ^t of injection molded plate) (2) Elution test: Conforms to the medical device testing method announced by the Ministry of Health and Welfare. (However, the pellet dissolution test was conducted at 121℃-
(1 hour treatment, 100℃-24 hour treatment for injection molded plates) (3) Elution amount analysis: IR analysis method Put 40 g of sample (20 to 50 mg/granule pellets) into a glass container, add 200 ml of distilled water, and heat in a steam cooker. Treatment at 121°C for 1 hour. Pre-adjusted fine powder CaCO ₃ (average powder diameter 1 μ or less) in 50 ml of the eluate 10
Take 10mg from a blend of mg and KBr200mg,
IR analysis using KBr tablet method, 1020cm ^-1 logIo/I〓
Calculate the intensity ratio of 870cm ^-1 Io/I and determine the elution amount (ppm) of the clarifying agent DMBS from the calibration curve prepared in advance. Remarks 1020cm ^-1 : Characteristic absorption band of DMBS 870cm ^-1 : Characteristic absorption band of CaCO ₃ (4) Molding test: Over 100 consecutive shots under general molding conditions (250℃) of 8oz injection molding machine, test piece (3mm) ^t ) was molded and the comparative evaluation was mainly performed on the release properties from the mold. (5) Thermal stability test: Compliant with JIS K7212. 1/3 area deterioration time of 0.5mm ^T sheet in 150℃ oven. Examples 1 to 3 DMBS for 100 parts by weight of polypropylene resin
and calcium lactate or/and calcium stearyl lactate in the amounts listed in Table 1 and thoroughly mixed with a Henschel mixer. The obtained mixture was extruded using a 40m/mmφ extruder.
The resin was pelletized at a temperature of 260°C and a test piece was injection molded. Next, the above-mentioned dissolution test was carried out using the obtained pellets, and the dissolution amount was analyzed. In addition, these pellets were melt press-molded into 0.5 mm sheets and a thermal stability test was conducted. The obtained injection test piece was submerged in water, and its haze level was measured before and after treatment at 100°C for 24 hours. All of these results are compared to the comparative example shown below.
The elution amount of DMBS and increase in haze were significantly small, and the moldability and thermal stability were good. Comparative Examples 1 to 5 The same procedure as in Examples 1 to 3 was carried out except that in Examples 1 to 3, a group metal salt of a fatty acid was blended instead of calcium stearyl lactate, and that it was not blended. The conventionally known blended sample of DMBS and fatty acid group metal salt had a large amount of DMBS eluted and a large increase in haze, and was inferior to Examples 1 to 3. On the other hand, the moldability and thermal stability of those without the mixture were poorer than those with the mixture.

[Table] Notes Additives and polymers used DMBS: Shin Nippon Chemical (Gel All MD) Calcium lactate: Kenei Pharmaceutical Co., Ltd. Calcium stearyl lactate: Musashino Chemical Research Institute (BELF) Calcium stearate and zinc stearate: NOF LDPE: Mitsubishi Yuka Yucalon YK-30 Polypropylene: All tris(2,4-di-
0.07 parts by weight of t-butylphenyl) phosphite and tetouquis [methylene-3(3,5-di-
t-Butyl-4-hydroxyphenyl)propionate] Contains 0.02 parts by weight of methane.

Claims (1)

[Scope of Claims] 1. A polypropylene resin composition comprising a polypropylene resin, 1,3,2,4-di(methylbenzylidene)sorbitol, and calcium stearyl lactate. 2 For 100 parts by weight of polypropylene resin,
The resin composition according to claim 1, which contains 0.01 to 1 part by weight of 1,3,2,4-di(methylbenzylidene)sorbitol and 0.01 to 1 part by weight of calcium stearyl lactate.