JPS61130352A - Stabilizer composition for organic material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a stabilizing composition for organic materials, and in particular to a stabilizing composition for organic materials, particularly for use in polymers such as polyolefins containing a phenol having a substituent that exhibits steric hindrance as an antioxidant. This invention relates to a stabilizing composition that can prevent yellowing and decomposition of.

[Conventional technology]

Polyolefins such as polyethylene and polypropylene are usually stabilized with hindered phenols.

The first hindered phenolic antioxidant was the well-known substance butylated hydroxytoluene, namely BHT (2,6-tart-butyl-p
-cresol), BI(T and its simple variants are sometimes referred to as monophenolic antioxidants, and BHT remains the most widely used of the monophenolics. Another antioxidant for phenols is 2-[or 3)-
There is tart-butyl-4-methoxy-phenol (butylated hydroxy-anisole, or BHA).

These compounds are effective in preventing thermal degradation of the polymer. However, compounds such as BHT tend to cause yellowing of the polymer.

The mechanism by which this yellowing occurs is uncertain, but is believed to be due to free radical reactions that occur when BHT provides hydrogen to prevent the formation of polymer radicals resulting from thermal decomposition of polymer chains.

When such a reaction occurs, a number of substances are produced, some of which, such as quinone methide dimer, cause yellowing of the polymer.

Another possibility is that, after oxidation, BHT undergoes a parentage-addition reaction with NOx or other nitrogen-containing gases, resulting in the replacement of the methyl groups of BHT with nitro groups. This reaction produces a pale yellow product.

Attempts have been made to add secondary stabilizers such as phosphites and thioesters along with BHT to prevent yellowing. No. 3,887,477, hydrazine is combined with 2,6-di-tar to stabilize polyolefins against oxygen, thermal and light degradation.
Used with t-butylphenol. US Patent No. 4
No. 454,270, polyolefins stabilized with various antioxidants such as BHT are further treated with triisopropanolamines, bipyridines and N,N-bis(2-hydroxymethyl) soyaamine (3oyaamine).
) are added to prevent discoloration.

[Summary of the invention]

The present invention provides a stabilized composition containing a hindered phenol antioxidant, such as BHT, and sodium borohydride (S B H).

Alternatively, the present invention provides a method for preventing discoloration of a material stabilized with a hindered phenolic compound, comprising adding SBH before, during, or after adding the hindered phenolic metal to the material. It is.

[Detailed description of the invention]

There are various methods for incorporating stabilizing components into materials such as polyolefins. According to the method, the olefin is solution polymerized in an organic solvent such as hexane, the stabilizing component is mixed into the polymer, and the solvent is removed by flashing. Alternatively, impaired phenols and SB
Either or both of H can be added to the molten polyolefin.

The hindered phenol and SBH can be added together or separately. For example, the hindered phenol can be added during the polymerization stage and the SBH can be added to the molten polymer.

Sodium borohydride (NaBH*) is a strong reducing agent that can prevent thermal degradation of polymers and/or regenerate impaired phenols, thus reducing the formation of yellow products such as quinone methides. hinder.

The amount of SBH to be mixed generally depends on the amount of hindered phenol present. If BHT is used, S B
The ratio of H to 13) TT is preferably the it ratio o, ot:
t to 2:1, typically 0.1:1. Considering the cost of SBH, lower ratios such as o, os:t are often preferred, and much lower ratios may be sufficient in many applications.

To stabilize polymers such as polyolefins,
Based on the electrolyte, the total amount of SBH is preferably in the range of 0.001 to 0.21% in the final mixture.

The SBH can also be mixed into the master bunch of the polymer, but then the proportion of both stabilizing components will be relatively higher; the master bunch is usually about 5 to 15 times its weight, Since it is typically mixed with about 10 times its weight of additional polymer, the stabilizing component can be mixed into the masterbatch in an amount about 10 times greater than that desired in the final mixture.

SBH has been found to be extremely effective in preventing backlash commonly seen in polyolefins stabilized with BHT and its analogs.

The invention will be further illustrated by the following examples.

Example 1 To test the stability of BHT in the presence of SBH, a small amount of benzoyl peroxide as a radical initiator was added to two test tubes containing samples of BHT. One of the test tubes also contained SBH. Both samples were kept in the oven for 24 hours to keep them liquid. The sample with SBH remained colorless, while the sample with BHT alone turned yellow.

This example shows that SBH can inherently prevent the discoloration of hindered phenols during radical formation. Thus, although the present invention is primarily intended for the stabilization of polyolefins, it may also be used in plastics, rubber, petroleum products,
It can also be applied to other organic substances such as fats and oils.

Example 2 This example demonstrates how sodium borohydride (S B H)
and, such as phosphites and DSTDP thioesters,
The performance is compared with a known commercially available secondary antioxidant for BHT-stabilized polypropylene. Extruded polypropylene films containing various antioxidant stabilizer systems were made. The effectiveness of these systems was determined by measuring resistance to polymer degradation, such as yellowness and whiteness index and melt index.

Made by sample m BHT in a Hen5chel mixer.

A triblend formulation was prepared by blending the antioxidant and calcium stearate processing aid with the unstabilized powdered polypropylene for 2 minutes.

The finished tri-blend was stored in a layer of plastic bags prior to pressing into pellets, then 3 inches (8,9 cm)
m) was extruded into ribbon strips. S with the same powdered polypropylene used to prepare the ribbon sample above.
Low levels of SBH were introduced with a 10% triblend concentrate prepared by diluting the BH.

Mixing was done in a Henschel mixer for 2 minutes.

Extruded polypropylene dry blend in % inch (3,2 mm
) was extruded into pellets. 34 inches (8°9 cm)
The ribbon was extruded from the pellet during the first pass through the extruder through five passes. The following conditions were used during pellet extrusion and during extrusion into ribbons.

Set temperature -210, 210, 210, 220℃RPM
-175 Die - Reaching inch (3,2I1m) rod across 3% inch (8,9cm) Ribbon cooling water Two hoppers - ON Extruder type - Single screw, inch (19 cranes)
Rel screw type - 3 stage type % type %: 1 Manufacturer - Haak Inc.
e, Inc.) Yellowness-Whiteness Index Two yellowness indices and one whiteness index of polypropylene sample (YII ASTM D 1925゜Yh Distillation^S
TMF! 313. Wl-^STME 313) About Hunter Lab D25A-9 Colorimeter ccrr:
tq3tCIE 2° standard measuring device, CIE light source C (Nikko)]. Only the value of Y E is reported.

The analysis was divided into two parts due to the directional composition of the sample.

The "subordinate" direction means that the longitudinal direction of the sample is parallel to the light beam (2), and the "opposite" direction means that the longitudinal direction of the sample and the light beam (2) are perpendicular. -Tingle, measured 5 times in one direction and averaged.

Melt Index Test 1 on Melt Index is Lowell (L
owell 1) I went to university. The test conditions are as follows.

Polypropylene with Substance Distabilizing Additives and Processing Aids Reference: ASTM 01238-79 Conditions:
L Temperature: 230℃ Full load: 2160 grams Approximate pressure crab 43.25 psi (298,2kP
a) Cylinder diameter: 9.5504 Tsurugui diameter: 2.0955±0.0051 Dragon preheating time = 2 minutes and 6 minutes Discharge time: 15 seconds Test time interval: 15 seconds Notes The first number of the sample number system is sample number, the second number is 0 which is the number of extrusions
For example, a sample written 2×1 indicates sample number 2 extruded once, and a sample written 3×5 indicates sample number 3 extruded five times.

Low concentration of sodium borohydride (SBHo, 01%)
delayed color development and polymer degradation of BHT-treated polypropylene compounds. When compared to common commercial secondary antioxidants such as phosphites, DSTDP thioesters, low levels of SBH show superior behavior in reducing yellow color development, improved loss of whiteness, and actual polymer degradation or showed a delay in strand scission.

Example 3 A series of tests were conducted to demonstrate the synergistic effect of SBH and BHT.

Various polyethylene slacks (let doevns)
) is Elasor Chemiplastics (Meerhout).

(Belgium) containing various amounts of SBH and BHT.

BHT is usually added in the form of a master bunch;
%SBH was prepared because SBH can be easily mixed into the polymer.

Preferred SBH loadings (0-300 ppm) and various amounts of BHT were combined.

Nine sample sheets were prepared.

Samples 1-5: Normally preferred BHT addition content of 1100-200 pp.

Sample 6-9: 1% BHT.

The content of SBH is shown in the following table.

Nine sheets were placed in a NOx atmosphere for 24 hours.

Untreated sample 1 showed slight yellowing. This is sample 2
It decreased in Sample 3-5 and disappeared in Sample 3-5. Therefore, 150 ppa is 100-200 ppa + B I-I
There appears to be an optimal content of S B H relative to the T content.

In Sample 6, the high content of BHT led to significant yellowing, but in Samples 7-9, a significant improvement in front peeling was observed. Therefore, the present invention is particularly useful with respect to color stability of polymers in applications requiring high content of hindered phenolic antioxidants.

Procedural amendment band (method) 1. Indication of case 1985 patent application No. 203253
No. 2, Title of the invention Stabilizing composition for organic materials 3
, Relationship to the case of the person making the amendment Applicant name: Morton Thiokol Incorporated 4, Agent

Claims (15)

[Claims] (1) A stabilizing composition for organic materials comprising a hindered phenol antioxidant and sodium borohydride (SBH). (2) The impaired phenol antioxidant is 2,6-di-t-
Butyl-p-cresol (BHT), 2-t-butyl-
4-methoxy-phenol and 3-t-phthyl-4-
A stabilized composition according to claim 1 selected from the group consisting of methoxy-phenol. (3) The impaired phenol antioxidant is BHT and SB
3. The stabilized composition of claim 2, wherein the weight ratio of H to BHT is from about 0.01:1 to about 2:1. (4) A method for stabilizing organic materials against oxidation and discoloration, characterized in that a hindered phenol antioxidant and sodium borohydride are added to the organic materials. (5) The method according to claim 4, wherein the organic material is a polymer. (6) The method according to claim 5, wherein the polymer is a polyolefin. (7) The method of claim 6, wherein the polymer is selected from polyethylene and polypropylene. (8) The total content of SBH in the polymer is approximately 0.00
6. The method of claim 5, wherein the amount is from 1 to about 0.2% by weight. (9) incorporating the SBH into a polymer masterbatch at a higher ratio than that required for the final polymer composition, and further mixing the masterbatch with the polymer, by about 0.001 to about 0.2 wt. 9. A method according to claim 8, characterized in that it provides a final mixture containing % SBH. (10) A polymeric composition comprising a polymer, a hindered phenolic antioxidant, and sodium borohydride (SBH). (11) The impaired phenol antioxidant is 2,6-di-t
-butyl-p-cresol (BHT), 2-t-butyl-4-methoxy-phenol and 3-t-butyl-4
- methoxyphenol. (12) The impaired phenol antioxidant is BHT and S
12. The polymer composition of claim 11, wherein the weight ratio of BH to BHT is from about 0.01:1 to about 2:1. (13) The polymer composition according to claim 10, wherein the polymer is a polyolefin. (14) The polymer composition according to claim 13, wherein the polymer is selected from polyethylene and polypropylene. (15) The total content of SBH in the polymer is about 0.
11. The polymer composition of claim 10, wherein the polymer composition is from 0.001% to about 0.2% by weight.