JPS6099147A - Polypropylene resin composition - Google Patents

Abstract

PURPOSE:To provide a polypropylene resin composition having high stability to radiation and excellent transparency, by mixing a polypropylene resin with a sorbitol derivative, a specific triaryl phosphite and a hindered amine stabilizer. CONSTITUTION:A polypropylene resin is compounded with (A) a sorbitol derivative of formula (R is H or 1-18C alkyl) [e.g. 1,3,2,4-di(ethylbenzylidene) sorbitol], (B) tris(2,4-di-t-butylphenyl) phosphite and (C) dimethyl succinate 2-(4- hydroxy-2,2,6,6-tetramethyl-1-piperidyl)ethanol condensate. The amount of the components A, B and C are 0.01-4pts.(wt.), preferably 0.02-2pts. each based on 100pts. of the polypropylene resin. USE:Food container or medical tool to be sterilized by radiation sterilization.

Description

Detailed Description of the Invention The present invention provides a polypropylene resin composition that exhibits little deterioration and physical property deterioration even when irradiated with radiation, is stable against long IvJ thermal history after radiation irradiation, and has excellent transparency. It is about things.

Polypropylene resin is widely used in food containers, medical instruments, etc. because it has excellent hygienic properties and molded products have semitransparency that allows the contents to be seen through.

However, in applications such as food containers and medical devices, it is important to be able to confirm that the contents, trapped garbage, and other foreign substances have not entered the container.・It is not desirable.

For this reason, it is currently desired to improve the transparency of polypropylene resins for this purpose.

In addition, food containers, medical instruments, etc. need to be sterilized before use depending on their intended use.Usually, heat sterilization using steam, gas sterilization using ethylene oxide gas, which has a strong sterilizing effect, Sterilization methods using a bed of peroxide water are used.

In recent years, radiation sterilization methods, which sterilize by irradiating radiation, have been developed and are increasingly being used to sterilize food containers or medical instruments.

Although polypropylene resin is stable for steam sterilization with steam, gas sterilization, and sterilization, it is not stable for radiation sterilization, and has the disadvantage of causing yellowing and deterioration of physical properties.

In particular, regarding the decrease in physical properties, by irradiating radiation, the outside of the impact-resistant system becomes less than half of what it was before irradiating the radiation, and if heat is applied immediately after irradiation, the decrease in physical properties is noticeable. This accelerates the embrittlement of polypropylene resin and causes brittle fracture.

In order to prevent the physical properties of polypropylene resin from deteriorating due to radiation irradiation, there are methods of adding specific stabilizers to polypropylene resin, such as adding only triarylphosphite, a combination of triarylphosphite and a hindered phenolic antioxidant, Combination of triarylphosphite and hindered amine light control and weathering stabilizer (Special Publication Publication 1987-
179234) 7゛"Ill:pJ"L"'CI-'6
・ (However, Tris IIIF (2,5-di-butylphenyl) 1 m phosphite or Tris a (2,5-butylphenyl)
4-J.

The stability of polypropylene resin molded articles against radiation exposure is still insufficient when only 1-butylphosphite is added to the phosphite. For this reason, it is desirable to use the stabilizer in combination with other stabilizers, such as 2,6-butyl-p-methylphenol, tetrakis[methylene-3(ro, 5-butyl-4-hydroxyphenyl)], etc. [Globionate] When used in combination with a hindered phenolic antioxidant such as methane, the amount of added silica should be sufficient to reduce the stability of the polypropylene resin molded product immediately after irradiation and after irradiation, as well as during thermal history. If used, yellowing of the molded product becomes a problem.

In addition, when used in combination with hindered amine light control and weathering stabilizers such as bis(2,2,6,6-titramethyl-4-piperidyl) sebacate or dimethyl succinate mef-1-piperidyl) ethanol condensate, polypropylene resin The radiation stability of the moldings is satisfactory, with no yellowing occurring at all.

Among them, the combined use of motris-(2,4-di-zuptylph,enyl)-phosphite and dimethylsuccinate 2-(4-hydroxy-2,2,6,6-tetramethyl-1-piperidyl)ethanol condensate! Since these stabilizers have good radiation resistance and are safe, compositions using them in combination are excellent for use in food containers and medical instruments.

However, polypropylene resin molded products containing these stabilizers have good radiation resistance, but
There is almost no transparency, so when this molded product is used to hold goods or medicines such as food or medical containers or syringes, it is difficult to check for small particles or foreign objects that may be mixed into the contents. Yes, and the exact color of the contents': J@
It has a serious drawback that it cannot be confirmed.

The present inventors achieved excellent radiation resistance. ] A study on improving the transparency of millipropylene resin molded articles was conducted using tris (2,4-di-1-butylphenyl phosphite and dimethyl succinate) 2-<4-hydroxy-2. 2,
6. 6-titramethyl-1-piperidyl) ethanol condensate was added together; j? When various crystal nucleating agents such as para-butylbenzoic acid aluminum salt, sebacic acid, or one sorbitol derivative were added to the IJ propylene composition, the general formula (I) 0 1-12o H (R is hydrogen) was added. Addition power of a sorbitol derivative represented by (atom or carbon number 1 to 18σ) representing an alkyl group;

The present invention was completed based on the discovery that it is possible to significantly improve the transparency of lopylene resin molded products while also maintaining sufficient radiation resistance.

That is, the present invention is directed to polypropylene resin io.

1 to 4 parts by weight of a sorbitol derivative represented by the general formula (1) (R represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms), tris(2,4-di-suptylphenyl) ) Phosphite 001-4 parts by weight and dimethyl succinate) 2-(4-
hydroxy-2,2,6,6-tetramethyl-1-piperidyl) ethanol condensate (hydroxy-2,2,6,6-tetramethyl-1-piperidyl) ethanol condensate 0.01 to 4 parts by weight. It is a transparent polypropylene resin composition.

The polypropylene resin used in the present invention may be any of a globylene homopolymer, a fluoropylene-ethylene copolymer, a propylene-α-olefin copolymer, or a mixture thereof.

In the present invention, it is essential to use a sorbitol derivative represented by the general formula (I) (R represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms), and the amount added is 0.01 to 4 parts by weight. , preferably 0.0
It is 2 to 2 parts by weight. Addition of less than 0.001 parts by weight has almost no effect on improving the transparency of the molded product, and addition of more than 4 parts by weight does not significantly increase the effect, and also reduces the amount of gold during molding. Severe protrusion into the mold causes trouble and is economically expensive.

In addition, in the present invention, tris(2,4-seeds-butylphenyl)phosphite and dimethylsuccinate 2
-(4-hydroxy-2,2,6,6-te) 7 :I
The addition of tyl-1-piperidyl) ethanol condensate is also essential.

The amount of tris(2,4-cy4-7"tylphenyl)phosphite added is 0.01 to 4 parts by weight, preferably 0.0
It's a 2-2 double regret. Addition of less than 0.01 parts by weight does not have a significant effect on stability after irradiation, and addition of more than 4 parts by weight does not significantly increase the effect and is not economically viable. This results in high prices and problems.

“Dimethylsakunne)2-(4-hydroxy=2,2.
The amount of the 6.6-tetramethyl-1-piperidyl) ethanol condensate added is 0.01 to 4 parts, preferably 0.02 parts.
~2 parts by weight. Addition of less than 0.01 parts by weight does not have a significant effect on stability after radiation irradiation, and addition of more than 4 parts by weight does not significantly increase the effect and is not economically viable. This results in high prices and problems.

Sorbitol derivatives represented by general formula (1), tris(2,4-di-1-butylphenyl)phosphite and dimethylsuccine 1-2 (4-hydroxy-2,
By using 9F 2,6,6-titramethyl-1-piperidyl) ethanol condensate, the effect becomes remarkable.

Using only the sorbitol derivative represented by the general formula (1), tris(2,4-di-l-butylphenyl)phosphite and dimethylsuccinate 2-(4-hydroxy-2,2,6,6-titramethyl- Transparency is excellent when 1-piperidyl) ethanol condensate is not used, but physical properties deteriorate and yellowing is severe after irradiation.
.

Without the use of the sorbitol derivative represented by the general formula (1), there is almost no effect of improving the transparency of the molded article, and one of the objectives of obtaining a polypropylene resin composition with excellent transparency cannot be achieved.

Dimethylsuccine 1-2 (4-hydroxy-
When the 2,2,6,6-titramethyl-1-pipe1]zyl)echno-7)v condensate is not used, the radiation resistance is inferior to that when the six components are used together.

It is expressed by the general formula <1), and a Solpi I--/shi derivative is used in combination with a dimethylsac/ne) 2-(4-hydroxy-2,2°6.6-tetramethyl-1-piperidyl) ethanol condensate. , g)) When phosphite (2,4-g-butylphenyl) phosphite is not used, the radiation resistance is insufficient compared to when a filter is used together, and the molding during molding. Processing stability becomes a problem.

If necessary, other additives such as antioxidants other than those mentioned above, ultraviolet absorbers other than those mentioned above, pigments, peracids, dispersants, neutralizing agents, etc. may be added to the materials of the present invention. I can do things.

In that case, the antioxidant used is 2,6-diχ
-butyl-p-methylphenol, n-octadecyl-
Otsu-(4-hydroxy-3,5=di-t-7 tylphenyl)gropionate, tetrakis[methylene-ro(6,
5-G-phthyl-4-hydroxyphenyl)propionate] methane, etc., but these additives are limited because they cause yellowing of the wood due to radiation exposure.

It is also possible to use sulfur-based antioxidants such as chlorinated querythritol-tetrakis-(β,-(1-uri-ropropionate), ./2-1-norithiopropionate), but they are hemolytic. Question h″′=Is that fl?
Use is limited.

As ultraviolet absorbers, 2-hydroxy-4-reiichi 7sI benzophenone, 2 (2/-hydroxy-
Representative examples include 6,5-di-butylphenylchlorobenzotriazole.

The melt flow index can be controlled by adding peracids (such as 2,5-dimethyl-2,5-bis(butylperoxy)hexane, diptyl perphthalate, and benyl peroxide). It is possible to improve moldability.

The resin and composition of the present invention include a polypropylene resin, a sorbitol derivative represented by the general formula (1), and a tris(2
．． 4-cy-1-butylphenyl) phosphite, dimethylsuccinate 2-(4-human waxy) 2. 2,
6. 6-tetramethyl-1-piperidyl) inhibitor,
It can be obtained by mixing an ultraviolet absorber, a peracid fls, etc. using a Henschel mixer or other blender, uniformly dispersing the mixture, and melting and pelletizing this using an extruder.

The resin composition of the present invention has extremely high stability against radiation irradiation and is transparent (also excellent in raw materials), so it can be effectively used for food packaging, medical instruments, and other uses by utilizing these properties. .

Hereinafter, the present invention will be explained in detail with reference to Examples.

Example 1 1.5 parts by weight of propylene-ethylene laminate)mer"; Inoprene EFB" (trademark, manufactured by Mitsui Toatsu Chemical Co., Ltd.) powder was added to 100 parts by weight. 3, ,2. 4-di(ethylbenzylidene)sorbitol 0. 3-h'' parts, thoinos(2,4-seeds-butylfer) phosphite o. o23i parts, dimethyl succinate) 2-C4-
Hydroxy-2. 2, 6. 6-titramethyl-1
-piperidyl) 0.02 parts by weight of ethanol condensate, 0.02 parts by weight of calcium stearate. Add 7 parts by weight, mix, and use a normal extruder. The pellets were made into pellets at an extrusion temperature of about 240"C using an injection molding machine at an injection temperature of about 240"C to a size of 160mm.
It was molded into a mm flat plate.

The obtained flat plate was exposed to 2.5 Mr. gamma rays from a Konokult 60 radiation source.
After ad irradiation, the sample was left for two weeks in an atmosphere of 80°C.

Impact resistance, transparency, and yellowing were examined before and after irradiation.

The impact resistance was determined by placing the flat plate on a nob with an inner pot of 50Aφ, applying a 1/2// striking core to it, dropping the load from the second part, and expressing the impact energy at the height of the crack. 3J Toatsu Kagaku Co., Ltd.).

Transparency was measured using a commercially available Havemeter (A
STM D1GO5).

Yellowing (・Evaluated by visual inspection as ◎, ○, △, and ×.

◎ indicates that no yellowing is observed, ○ indicates that yellowing is present, △ indicates that yellowing is present, and × indicates that yellowing is severe.

The results are shown in Table →.

Example 2 In Example 1, the amount of tris(2,4-butylphenyl)phosphite added was 0.053 fj,
Dimethyl succinate 2 (4-hydroxy-2,2,6
, 6-tetramethyl-1-piperidyl) ethanol condensate was increased to 0.005 parts by weight, and molded in the same manner as in Example 1 to obtain a flat plate.

Similar evaluations were made below.

The results are shown in Table-1.

Example 6 In Example 1, the addition of tris(2,4-di-butylphenyl)phosphite was 0.08'M
Quantity part, dimethyl succinate 2-(4-hydroxy-2
, 2,6,6-tetramethyl-1-piperidyl) ethanol condensate was increased to 0.08 parts by weight, Example 1
A flat plate was obtained by molding in the same manner as above.

Similar evaluations were made below.

The results are shown in Table-1.

Comparative Example-1 In Example 1, tris(2,4-seed-butylphenyl)phosphite and 0.dimethylsuccinate 2-
(4-hydroxy-2,2,6,6-titramethyl-1
-piperidyl) without using the ethanol condensate, by cooling the tetrakis[methylene-5(3,5-di,?, -phthyl-4-hydroxyphenyl)furopi]onate methane 01' heavy-leaf part. Example 1
A flat plate was obtained by molding in the same manner as above.

Similar evaluations were made below.

The radiation resistance of this product is inferior to that of the second product of the present invention.

Comparative Example-2 In Example 3, 1.3.2.4-G (Eng. 5-)
A flat plate was obtained by molding in the same manner as in Example 1, but without using (benzylidene) sorbitol.

Similar evaluations were made below.

Although radiation irradiation properties are good, transparency is poor.

Comparative Example-3 In Example B, monodimethyl succinate 2-((4-
Example 3 except that hydroxy-2,2,6,6-tetramethyl-1=piperidyl) ethanol condensate was not used.
A flat plate was obtained by molding in the same manner as above.

Similar evaluations were made below.

The radiation resistance of this product is inferior to that of the composition of the present invention.

Comparative Example 4 In Example B, a flat plate was obtained by molding in the same manner as in Example 3 without using tris(2,4-di-suptylphenyl) phosphite.

Similar evaluations were made below.

The radiation resistance of this product is inferior to that of the composition of the present invention.

Comparative Example 5 In Example B, tetrakis[methylene-3(3,5 -di-l-butyl-4-hydroxyphenyl)gropionate] 0.1 part by weight of methane is added,
The rest was molded in the same manner as in Example 6 to obtain a flat plate.

Similar evaluations were made below.

This item showed severe yellowing immediately after radiation exposure.

Comparison/Column-6 In Example B, bis(2,2,6,
6-tetramethyl-4-piperidyl) sebacate 01
A flat plate was obtained by molding in the same manner as in Example 6 except that part by weight was added.

The radiation resistance of this product is inferior to that of the composition of the present invention.

Supplementary manuscript (spontaneous) January 10, 1982 Mr. Kazuo Wakasugi, Commissioner of the Patent Office 1.Display of the incident 1981 Patent Application No. 206004 2. Name of the invention Polypropylene resin composition 3. Person who makes corrections Claims and detailed description of the invention in the specification 5 Contents of amendment (1) The scope of claims shall be supplemented as shown in the attached sheet.

(2) Change “necessary” to 1 in the first line of page 3 of the statement.
"It's necessary," he corrected.

(3) Change "carbon atom" in the 9th line from the bottom of page 7 to "
The number of carbon atoms” is corrected.

(4) "Propylene-α-olefin copolymer" in the second line of page 8 is corrected to "propylene-α-olefin copolymer."

(5) Change "carbon atom" in the 7th line from the bottom of page 8 to "
The number of carbon atoms” is corrected.

(6) 1 methylene-6 (ro,
5-G” is corrected to “methylene-3-(3,5-G”).

(7) "Dimethylsuccinate 2 (4-hydroxy)" in the 10th line of page 15 of the same book is changed to "dimethylsuccinate-"
Corrected as 2-(4-hydroxy).

(8) “Methylene-6 (3,
"5-di-t-butyl" is corrected to "methylene-6-(ro, 5-di-t-butyl").

Attachment 2, Claim 1, General formula (for 100 parts by weight of polypropylene resin)
1) 0.01 to 4 parts by weight of a sorbitol derivative represented by the formula % (R represents 7 hydrogen atoms or an alkyl group having 1 to 18 carbon atoms);
) IJ Su(2,4-cy1-7'tylphenyl)phosphite 0.01-4 parts by weight, dimethylsuccinate 2-(4-hydroxy-2,2,6,6-tetramethyl-1-piperidyl) A polypropylene resin composition having good stability against radiation irradiation and excellent transparency, characterized in that it is formed by mixing 101 to 4 parts by weight of an ethanol condensate.

Claims (1)

[Claims] 1. General formula (
1) 0.01 to 4 parts by weight of a sorbitol derivative represented by the formula % (R represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms);
Tris(2,4-butylphenyl)phosphite) 0. (11-4 parts by weight, dimethylsuccine)2-(
4-hydroxy-2,2,6,6-tetramethyl-1-
1. A polypropylene resin composition having good stability against radiation irradiation and excellent transparency, characterized by mixing 1 to 4 parts by weight of (piperidyl) ethanol (i) compound o, o.