JPS62227988A - Heat-resistant and antibleeding antioxidant - Google Patents

Abstract

PURPOSE:To provide an antioxidant having a high melting point, excellent heat resistance and an excellent antibleeding property as compared to those of conventional antioxidants, which comprises a particular cyclic p-phenylphenol compd. as the main component. CONSTITUTION:This heat-resistant and antibleeding antioxidant comprises a cyclic p-phenylphenol compd. of formula I (wherein X is a hydrogen atom or a methyl group; R is a hydrogen atom or a 1-8C alkyl group; and n is an integer of 4-10). It is pref. that the cyclic p-phenylphenol compd. content be 80wt% or more. This cyclic p-phenylphenol compd. can be obtd., e.g., by thermal reaction of a p-phenylphenol with an aldehyde in an inert solvent in the presence of an alkali metal catalyst, followed by isolation of the compd. from the product. This antioxidant is applicable to various plastics, various rubbers, lubricants, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an antioxidant having excellent heat resistance and bleed resistance.

[Conventional technology]

Generally, in order to prevent oxidative deterioration or thermal deterioration of plastics, rubber, etc., several percent of antioxidants are added to polymeric substances together with ultraviolet absorbers and the like. Conventionally, phenolic antioxidants are mainly used for plastics and amine antioxidants are mainly used for rubber to supplement generated radicals, and sulfur and phosphorus are also used to decompose peroxides. A type of antioxidant is also used. The total number of these antioxidants is over 300, of which around 100 are phenol-based alone, but most of them are low-molecular compounds, and at high temperatures they decompose or volatilize and lose their antioxidant effect. Secondary damage may occur due to decomposition products and volatile matter. In addition, in applications where plastic molded articles are immersed in organic solvents, oils, liquids, etc., low molecular weight antioxidants have the disadvantage of bleeding into these solvents.

Therefore, for applications requiring extreme heat resistance or bleed resistance, high molecular weight phenolic antioxidants or high melting point low molecular weight phenols such as p-phenylphenol are used.

[Problem that the invention seeks to solve]

Conventional polymeric phenolic antioxidants have improved heat resistance, volatility, and bleed resistance compared to low molecular weight antioxidants, but their melting point is 180 to 240°C, and they cannot be molded at higher temperatures. Its heat resistance has been insufficient for use as an antioxidant for engineering plastics, which undergoes heat treatment, and for applications where use is expected to occur at higher temperatures.

The present invention provides an antioxidant that has a higher melting point, better heat resistance, and better bleed resistance than conventional antioxidants.

[Means for solving problems]

The heat-resistant, bleed-resistant antioxidant of the present invention has the general formula (wherein, X represents a hydrogen atom or a methyl group, R represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and n represents 4 to 10 represents an integer value of ).

To produce the above p-phenylphenol cyclic product,
JP-A-59-104331, JP-A-59-104
Alternatively, p-phenylphenols such as p-phenylphenol and p-alkylphenylphenol and aldehydes are mixed with an alkali in a nonpolar solvent. It can be obtained by separating the product from a heated reaction using a metal as a catalyst. The aldehydes used in this case, such as formaldehyde and acetaldehyde, are used in an excess of 1.1 to 2.5 moles per mole of phenol. In addition, as non-polar solvents, organic solvents with a boiling point higher than 120°C, which is the temperature required for the cyclization reaction, and a dielectric constant of 3 or less at 20"C, are suitable for p
-5 to 20 parts per 100 parts by weight of phenylphenols
Parts by weight are used, preferably aromatic xylene, mesitylene, ethylbenzene, cumene, tetralin,
1,4-dioxane etc. are used.

The catalyst is sodium hydroxide, potassium hydroxide, potassium t-butoxide, etc.
It is used in an amount of 0.02 to 0.5 mol per 1 mol of i.

The phenolic cyclic product of the present invention has a melting point of 300°C or higher and exhibits poor solvent solubility when the number of condensed units is 4 or more. Therefore, in the present invention, it is not necessary to have a single number, and the number of condensed units is 4 to 4.
A mixture of two or more of the ten cyclic bodies may be used.

The scope of application of the antioxidant according to the present invention is not particularly limited, and includes olefin polymers such as polyethylene and polypropylene, vinyl polymers such as polyvinyl chloride and styrene, and various plastics such as ABS resin and MBS resin. , polyester resins such as polyethylene terephthalate and polybutylene terephthalate, nylon,
It can be applied as an antioxidant for engineering plastics such as polycarbonate and polyphenylene sulfide, various rubbers such as NBR and SBR, and oils such as turbine oil and lubricating oil.

Moreover, the applied amount is in the range of 0.1 to 2% by weight.

The antioxidant of the present invention may contain some other additives and antioxidants in addition to the cyclic p-phenylphenols in order to improve its antioxidant effect. For example, benzophenone-based ultraviolet absorbers to prevent radical reactions from starting, sulfur-based antioxidants such as dilaurylthiopropionate and distearylthiodipropionate to decompose generated peroxides, and triphenyl It is also possible to add phosphorous antioxidants such as phosphite and diphenylisodecyl phosphite, and other metal deactivators. However, when these additives are added, it is preferable to keep the total M of these additives in the antioxidant of the present invention to less than 20% by weight in consideration of the overall heat resistance and bleed resistance.

〔Example〕

EXAMPLES The present invention will be explained below with reference to Examples, but the scope of the present invention is not limited by these Examples.

Examples 1 and 2 68 g of p-phenylphenol, 30 g of paraformaldehyde and 500 ml of xylene were placed in a four-way flask equipped with a stirring device, a temperature system, a water meter and a cooling tube, and 16 ml of 5N sodium hydroxide solution was added. Heated. The reaction was carried out at reflux temperature for 5 hours while removing the produced condensation water. After cooling, the generated precipitate was filtered off and thoroughly washed with methanol, acetic acid, and warm water. After drying, chloroform 21 was added, refluxed for 2 hours, insoluble materials were removed by pressure filtration, the filtrate was concentrated, methanol was added to perform reprecipitation, and the mixture was divided into three fractions.

These products have almost a single peak in GPC (eluent THF), and the first fraction has a dispersity d = 1.
．． 02, number average molecule MMn = 1036, second fraction, dispersity d = 1.01, number average molecule 1Mn = 945
Met. In addition, the IR spectra of these two fractions show a shift to the lower wavenumber side of the hydroxyl group (3178 cm-' and 3188 cm-', respectively) due to the cyclic structure, and an absorption of 1.4-substitution (832 cm-'
) disappears and a new 1. 2. 3. 5 = substitution (87
Since an absorption of 6 cm-') appeared, it was confirmed that the benzene having a hydroxyl group was a cyclic body bonded at the 0-position of each hydroxyl group.

Next, in order to investigate the effects of these cyclic bodies as antioxidants, we investigated polypropylene (PP) and polybutylene terephthalate (PP) without other additives or antioxidants.
BT), add 0.2% by weight of the above fraction 1 or 2, and use a plastic tube to mix 5% at 20 rpm.
Minute molecules (liif kneading, then the rotation speed is 1100 rpm)
The torque value was measured 10 minutes after increasing the torque. A low torque value means that the molecular chain is broken due to oxidation and the molecular weight is reduced. The results are shown in Table 1.

As a comparative example, 0.2% by weight of BIT was added and a similar test was conducted.

As is clear from Table 1 below, if the resin without antioxidant is used as it is, the molecular chains will be cut due to heat and mechanical shearing force, and the torque value during kneading will drop significantly. On the other hand, B I T used in the comparative example has an effect when using polypropylene at a test temperature of 200°C, but has no effect when using polybutylene terephthalate at a test temperature of 250°C. On the other hand, in Examples 1 and 2 in which the p-phenylphenol cyclic product of the present invention was blended, 250
Even in the case of polybutylene terephthalate at ℃, the decrease in torque value is small.

Furthermore, the p-phenylphenol cyclic product of the present invention has a solubility of 1ff in organic solvents such as alcohol and acetone.
It was less than 1%.

From the above, the antioxidant containing the p-phenylphenol cyclic product of the present invention has heat resistance such that it exhibits a considerably high antioxidant effect even at high temperatures to which conventional antioxidants cannot be applied, and It can be seen that it can be used even under conditions where it is immersed in organic solvents or oil, and has excellent bleed resistance.

〔Effect of the invention〕

The heat-resistant and bleed-resistant antioxidant according to the present invention has excellent heat resistance and bleed resistance, and has great industrial value.

Claims (1)

[Claims] 1. General formula (wherein, X represents a hydrogen atom or a methyl group, R represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and n represents an integer value of 4 to 10) .) A heat-resistant and bleed-resistant antioxidant characterized by containing a p-phenylphenol cyclic substance represented by the following formula. 2. The heat-resistant and bleed-resistant antioxidant according to claim 1, which contains 80% by weight or more of p-phenylphenol cyclics.