JPS62138545A - Polypropylene based resin composition - Google Patents

Abstract

PURPOSE:A composition, obtained by blending a polypropylene based resin containing substantially no chlorine with dibenzylidenesorbitol and capable of suppressing the decomposition of the sorbitol in kneading and giving molded articles having good transparency. CONSTITUTION:A composition obtained by blending (A) 100pts.wt. polypropylene based resin containing substantially no chlorine with (B) 0.01-5pts.wt. dibenzylidenesorbitol. A resin prepared by adding and kneading a stabilizer having chlorine capturing property, e.g. selected from metal salts of fatty acids, alkyllactic acids or lactic acid with polypropylenbe based resin is used as the component (A). A component (B) having the surface treated with the stabilizer having chlorine capturing property may be blended. 1.3,2.4-Dibenzylidenesorbitol or 1-3,2.4-di(alkyl-benzylidene)sorbitol may be used as the component (B). USE:A packaging material for food containers and medical instruments.

Description

[Detailed description of the invention]

(Technical Field of the Invention) The present invention relates to a polypropylene resin composition with improved transparency, which prevents the presence of a specific clarifying agent during kneading (heat molding). The present invention provides a polypropylene resin composition that is particularly useful for food containers, packaging materials, medical instruments, and the like. (Prior art and its problems) As a method for improving the transparency of polypropylene resins, JP-A-22740 discloses a method of adding 1.;3,2.4-dibenzylidene sorbitol to polypropylene or its copolymer. Hereinafter, simply abbreviated as DBS) was published in Japanese Patent Application Publication No. 5
:(-117044, JP-A-5 Ei -:(011
/I Q, 1:1:1 1982-2251/43 M etc. include polypropylene or its copolymer Kogo 1.1. =
)・4-di(alkylhenzylidene)sorbitol (hereinafter simply abbreviated as I) Al-18) is proposed to be heated and formed on the placement table 1. On the other hand, metal salts of higher fatty acids (aliphatic metal salts) such as late calcium stearate and zinc stearate, metal salts of lactic acid, and the like are generally added to polypropylene resins as stabilizers or lubricants. When heat molding is performed by mixing the above-mentioned clarifying agent (S or D A II S and stabilizer) with polypropylene resin, an odor may be generated during heat molding, or j: There is no scale-C that causes health and safety problems, especially in the fields of use such as food containers and packaging materials and medical instruments, as organic substances are leached from the molded product. It also has the disadvantage of impairing the long-term sustainability of transparency. (Means for solving the problem) The present inventors used dibenzylidene sorbitol such as I) ) (S or I) A FIS. In order to solve the above-mentioned problem 1 (1) of polypropylene resin compositions, we first focused on the problem of odor generation during heat molding and the elution of organic substances from molded products. As a result, it was found that the cause of the above phenomenon was benzaldehyde or alkylbenzaldehyde, which is generated when dibenzylidene sorbitol is decomposed by chlorine, which is generally contained as a catalyst residue in polypropylene resin, during kneading and molding () Therefore, as a result of intensive study on preventing the production of benzaldehyde or alkylbenzaldehyde due to the decomposition of hensylidene sorbitol, we found that our problem could be solved by using a polypropylene resin that is substantially free of chlorine. The present inventors have found that 100 parts of polypropylene resin substantially free of chlorine and 0.01 to 5 parts of dibenzylidene sorbitol are used. The present invention is characterized by the use of a polypropylene resin that is substantially free of chlorine. Since dibenzylidene sorbitol (hereinafter also simply referred to as sorbitol) does not decompose to produce benzaldehyde or alkylbenzaldehyde during melt-kneading during hot molding of the composition, there is no odor during melt-kneading or from the resulting molded product. It is possible to prevent the elution of 41 substances mainly composed of benzaldehyde or alkylbenzaldehyde. Therefore, in the present invention, the polypropylene resin that does not substantially contain chlorine refers to the polypropylene resin composition containing sorbitol. It is a polypropylene resin that contains virtually no free chlorine (chlorine ion) that reacts with the sorbitol during melt-kneading, and has a density of 1 ppm or less. Such a polypropylene resin that does not actually contain chlorine can be obtained by, for example, a method using a highly active propylene polymerization catalyst. It can be obtained by controlling the polymerization conditions, or by purifying the polypropylene polymer by repeatedly washing it with hydrochloric acid, alcohol, water, etc. after polymerization. However, such polymerization and purification methods are industrially complicated. 1111 On the other hand, polypropylene resins obtained by conventional polymerization catalysts and polymerization methods mainly using chlorine-containing compounds such as titanium compounds and organoaluminum compounds generally have 1
Contains less than ppm-L of chlorine. In the present invention, by blending a stabilizer with a chlorine-scavenging property (hereinafter also referred to as a stabilizer) into the chlorine-containing polypropylene resin, free chlorine that reacts with sorbitol during melt-kneading is removed. It can be made into a pyrene-based resin containing substantially no boria [1]. The method for adding stabilizers to polypropylene resin containing chlorine is as follows:
A method of blending a Moetsuko stabilizer by blending sorbitol into the polypropylene resin, and a method of surface treatment with a stabilizer to the polypropylene resin! A method of kneading the sorbitol compound is preferably used. According to these methods, the chlorine present in the polypropylene resin does not directly react with the sorbitol during melt-kneading.
All the problems mentioned above are solved. In the present invention, the polypropylene resin containing C and chlorine is particularly E titanium chloride as mentioned above. A medium-stretched polymer (homopolymer) of propylene produced using a chlorine-containing compound such as diethylaluminilla 11 monocrite as a catalyst component, or polypropylene with a propylene content of 70% by weight or more and ethylene, butene, pentene, IliMI vinyl , a copolymer of one or more of vinyl chloride, and a blend of these polymers. Further, the stabilizer used in the present invention is 1b: elemental t+-I
1"l and exhibits an excellent effect on improving the fluidity, moldability, dispersibility, etc. of polypropylene resins (≠), especially aliphatic metal salts, alkyl lactate metal salts, and lactate metal salts. At least one selected from the following is preferable.Among these, alkyl lactate metal salts and/or lactate metal salts are used to control the decomposition of sorbitols and to prevent sorbitols from leaching into water, hot water, and steam. I(-because I can do it)

【)stomach. The stabilizer for the aliphatic metal salt used in the present invention and (/-
C is, for example, calcium stearate or aluminum stearate. Although there are known stearin compounds such as magnesium stearate, calcium stearate is preferably used. As the alkyl "A" acid metal salt stabilizer, the main components are milk lIl!2 (2-lactyl "7t, acid) with a degree of polymerization of 2 and a calcium salt of a stearic acid esterification reaction product (stearic acid). A small amount of 1 mo 11 consecutive acids [with 1 salt? Calcium stearate 11, which is a '+a compound, is commonly used, but other known compounds can be used without limitation. In addition, calcium lactate is commonly used as a metal lactate j', i stabilizer;
1) H, for example, lactic acid variuno 1. Known materials such as bent lead acid and magnesium lactate can be used without particular limitation. The composition of such stabilizers varies depending on the use. ,l
, j, but it is generally 0.01 to 10j parts, particularly 0.05 to 0.j parts per 100 parts of polypropylene resin.
A 5-layer electrical part is preferred. If the amount of stabilizer-containing paper is less than 0.0 parts by weight, chlorine in the polypropylene resin cannot be sufficiently captured. Therefore, when a polypropylene resin composition is then subjected to heat molding after blending sorbitol, the effects of the present invention are difficult to be exerted because the organic substances mainly containing benzaldehyde or alkylbenzaldehyde are purified. The moldability and thermal stability are also poor. On the other hand, if the paper containing the stabilizer is more than 1 electric part,
Not only does the effect of the present invention reach a plateau, but also the physical properties of molded articles obtained from the polypropylene resin composition deteriorate. In addition, in the present invention, the aspect of pushing the sorbitol outward with the stabilizer is a state in which a part of the surface of the sorbitol (more than 50% of the surface area) or a total of 1 to 11 is coated with the stabilizer in a layer. The method for achieving such a state is not particularly limited, but the method is preferably used. In other words, after mixing the stabilizer and sorbitol in a conventional manner, The sorbitol is heated at a temperature higher than the melting point of 1-Cj, and the sorbitol is coated with the molten stabilizer, then cooled and pulverized. When mixing 11 parts of sorbitol, it is common to use 1 part by weight of stabilizer to 1 part of sorbitol, and the ratio of stabilizer to 1 part of sorbitol is preferably 1 or more. Methods include melt-kneading and pulverizing-kneading methods, and heating methods using ball mills and jet mills are particularly used. As the sorbitol used in the present invention, the above-mentioned DBS or D A to 3 S is preferable, and those I
) l(S or 1) A HS is not particularly limited as long as it is a condensation product of sorbitol and benzaldehyde or alkylbenzaldehyde, but among others, ]・;(.2,4-dibenzylidene sorbitol, 1・:(.2・4-di(methylbenzylidene) sorbitol, lφ
3,2φ4-di(ethylbenzylidene) sorbitol,
1.;(,2.4-di(propylbenzylidene) sorbitol is preferably used. The blending ζ of such sorbitol is 0.01 to 5 parts by weight per 100 parts by weight of the polypropylene resin, and is 0.1
~1 part by weight is preferred. The amount of sorbitol added is 0.
If the amount is less than 01 parts by weight, the transparency will be low, and even if it is more than 5 parts by weight, not only will the effectiveness of transparency be reduced,
The polypropylene resin composition deteriorates the physical properties of the molded product. In addition, in the case of sorbitol that is surface-treated with a stabilizer, there may be some holes depending on the application, but 0.01 to 5 pores of sorbitol that have been surface-treated with stabilizer-C 13P per 100" Ftm of polypropylene resin. part, preferably 0.1 to 1 part by weight, of sorbitol surface-treated with a stabilizer (1,01 parts, if less than 1 part, transparency, moldability, thermal stability 1')
is inferior, and the effects of the present invention are not exhibited. On the other hand, if the amount of sorbitol surface-treated with a stabilizer is more than 5 parts, it is preferable because the effect of the present invention may be reduced or the weight of the molded article obtained by the composition will be lower. ()＜No. In addition, the polypropylene resin composition of the present invention may contain an antioxidant, an antistatic agent, a lubricant, a dispersant, a gr
Additives such as T additives, fluorescent agents, flashkillers, light stabilizers, ultraviolet absorbers, metal deactivators, and photodegradation accelerators can be added to a range that does not reduce the effects of the present invention. CN+!
It can also be used as a surface treatment agent for sorbitol. The method of kneading and molding the polypropylene resin shell 1 composition according to the present invention is not particularly limited, but as described in 1iir, depending on the chlorine content of the polypropylene resin used, the combination of the stabilizer and sorbitol if1 is necessary. The order and blending form may be determined. In other words, polypropylene that does not substantially contain chlorine is also 1
When using fatty pepper 1 product, the order of blending, kneading,
A conventional method is also used for molding. On the other hand, when using a polypropylene resin containing chlorine, sorbitol treated with a stabilizer in Table 1F+7 may be kneaded and used for molding. In addition, when using a polypropylene resin containing chlorine, a two-stage kneading method in which the stabilizer is kneaded and then the sorbitol is kneaded is a method in which shearing force is applied at the same time as heating and melting, and the stabilizer and There are no particular limitations on the method as long as the sorbitol is uniformly dispersed inside the polypropylene resin. For example, basically two extruders can be used and each can be operated in batch mode, but this method is complicated. To prevent this, use an extruder with two kneading zones, each with an injection port, and feed the polypropylene resin and stable I''Il+ from the injection port in the first stage. After passing through the 11 kneading zones, sorbitol is injected into the second inlet, either as it is or with a liquid suspension mixed with masterbatch pellets or dioctyl phthalate (DOP). A method in which the extruder passes through a kneading zone is preferred.In this case, the extruder is
Kneading son screw length I2) and screw diameter (
The larger the ratio (1,/D) of 1)), the more effective it is.
．． /l) is 15 or more, preferably 1. < is 18 or more, L-
, is. After kneading, various molded products can be molded according to the desired molding method. (Takagu) As described above, the polypropylene resin composition of the present invention uses a chlorine-free polypropylene resin, a stabilizer, and sorbitol, so it is particularly difficult to decompose sorbitol during kneading. It is possible to control the temperature and produce a good transparent molded product. (Examples) Hereinafter, the present invention will be specifically explained based on Examples, but the present invention is not particularly limited to the following Examples. 1) Haze: Based on ASTM Dloo;)-61 (
01 molded plate 3mmt). 2) Dissolution test 2 [1 Based on the standard method for testing plastic containers for infusions (I21°C - 1 hr treatment). I3) Elution amount analysis: UV absorbance analysis method. 40 g of 20-50 B/grain pellets were put into a glass container, 200 ml of distilled water was added, and the mixture was treated in a steam pot at 1211:1 hr. The eluate was
V analysis was performed to determine the absorbance near 260 mm, and from the pre-prepared test line, sorbitol (+) 11
S or I) A)) Elution amount of benzaldehyde or alkylpenzaldehyde, which is a decomposition product of
pm) was calculated. 4) Moldability test: 807. A test piece (3 mm t) was molded continuously for more than 100 shots under the general molding conditions of an injection molding machine (250°C), and the test piece (3 mm t) was mainly compared for the flexibility from the mold. 5) Thermal stability test: Compliant with ITS K7212. IF of 0.5mmt sheet) 0'('1/73 area deterioration time in oven. E;) Pellet preparation: Kobe Steel 65 m/rn
The obtained strand was cooled with water and cut into pellets. Examples 1-17.゛Types shown in Table 1]) l(S or D A l(S
and stabilizer at a ratio of 1:l, and D in N2 gas.
BS or ]) A Heating at a temperature below the melting point of BS and above the melting point of the stabilizer. After cooling, the surface was coated with a stabilizer]
) Grind S H or D A 11 S with a mixer. Next, I) B S or F surface treated with this stabilizer
') Polypropylene resin 10C whose ABS is shown in Table 1
) For the small acid part (), 4 parts by weight were combined and thoroughly mixed in a Henschel mixer. The resulting mixture was processed using a 65 m/m vented extruder.
The resin was pelletized at a temperature of 60°C and a test piece was injection molded. The above-mentioned dissolution test was carried out using such pellets,
Eluted acid analysis was performed. Also, these pellets are 0.5mm
+: A sheet was melt press-molded and a thermal stability test was conducted. The results are summarized in Table 1. These results are both T) compared to the comparative example shown below.
The elution amount of benzaldehyde or alkylbenzaldehyde, which is a decomposition product of B S or I) A RS, was significantly small, and the moldability and thermal stability were good. Comparative Examples 1 to f (I' shown in Table 1 for 100 parts by weight of polypropylene resin) 2 parts by weight of BS or DABSo and 0.2 parts by weight of stabilizer
When the heavy paper portion was simply mixed and blended, the same procedure as in Example 1 was conducted for the case where the heavy paper portion was not blended. The results are summarized in Table 1. 1) A mixed blend sample of lis or I) A 11 S and a stabilizer has a large amount of elution of benzaldehyde or alkylbenzaldehyde, which is a decomposition product of DBS or r) ABS,
It was inferior to the example. jH:15': Polypropylene contains 0.07 parts by weight of tris(2,4-di-t-butylphenyl)phosphite and tris(3,5-di-t-t) as antioxidants.
-Butyl-4-hydroxyphenyl) isocyanurate O, (13 parts by weight) was blended. Examples 18 to 33 To 100 parts by weight of powdered polypropylene (Toku II + Soda), tris (2, 0.07 tfl' part of 4-di-t-butylphenyl) phosphite, tris(3,5-di-t-butyl-4-hydroxybenzyl)
A total of 0.15 parts by weight of one or two of the stabilizers shown in Table 2 and 0.03 parts by weight of isocyanurate were mixed together using a Henschel mixer. The resulting mixture was pelletized using a 65 m/mφ milling machine at a resin temperature of 2:10°C. Next, this pellet is coated with I) B S or D A BS shown in Table 2.
0.25 parts were mixed thoroughly in a tumbler, and pelletized using an extruder with a width of 85 m/mφ at a resin temperature of 260°C. Using this pellet, moldability, thermal stability, haze, and elution amount were measured using the test methods described above. The results are summarized in Table 2. Examples 34 to 37 Using a 65 m/mφ extruder with L/D = 18 to the vent hole, the Henschel mixer mixture prepared in Examples 18, 21, 24, and 28 was charged into the hopper, and the mixture was poured into the DOP. Then, a liquid material in which DBS or DA BS shown in Table 2 was mixed and suspended was added to polypropylene r) BS or DA BS.
Continuously mix BS from the vent hole (in a part of the cylinder) so that 0.25% of BS is mixed in the heavy electric part, and keep the resin temperature at 260°C.
Pelletized at °C. Table 2 below shows the results measured by the above-mentioned test method. Comparative Examples 11-17 Example I El,] 9,20,23,24,25°2
9 and 3:1 and a composition without a clarifying agent in a Henschel mixer? 14 joints, 65m/mφ
The mixture was kneaded once using an extruder at a resin temperature of 260°C to form pellets. Table 23 below shows the results measured based on the above-mentioned measuring method.

Claims (1)

[Claims] 1. Polypropylene resin that does not substantially contain chlorine 1
0.01 to 0.00 parts by weight of dibenzylidene sorbitol
A polypropylene resin composition consisting of 5 parts by weight. 2. A polypropylene resin composition according to claim 1, in which a polypropylene resin that does not substantially contain chlorine is obtained by adding and kneading a stabilizer having chlorine-capturing properties to a chlorine-containing polypropylene resin. thing. 3. The polypropylene resin composition according to claim 1, wherein dibenzylidene sorbitol surface-treated with a stabilizer having chlorine scavenging properties is blended into a polypropylene resin containing chlorine. 4. Dibenzylidene sorbitol is 1, 3, 2, 4-
The polypropylene resin composition according to claim 1, which is dibenzylidene sorbitol or 1,3,2,4-di(alkylbenzylidene) sorbitol. 5. The polypropylene resin composition according to claim 2 or 3, wherein the stabilizer having chlorine scavenging properties is at least one selected from aliphatic metal salts, alkyl lactate metal salts, and lactate metal salts. thing.