DE1694939C - Stabilizing polymers - Google Patents

Description

form, as an to be incorporated, against decomposition by light stabilizing additive to resinous Polymers.

The resinous polymers are often subject to photodecomposition when exposed to outside or inside light such as sunlight or ultraviolet light. To protect against it are already several types of stabilizers have been proposed. In particular, are considered to be cheap light stabilizers recommended 2- (2'-Hydroxy-5'-methylphenyI) -benzotriazole, 2 - hydroxy - 4 - η - octoxybenzophenone, 1,1 bis (2 - methyl - 4 - hydroxy - 5 - tert-butylphenyl) -n-butane and the like

The subject of the invention is a piperidine-N-oxylspirohydantoin of the general formula (I)

55

6o

wherein R, and R, can be the same or different and represent a lower alkyl group or together with the carbon atom to which they are attached a 5- or 6-membered saturated homocyclic Ring or grouping of the formula

CH ₃ CH ₃

N-O-

CH ₃ CH ₃

form, as an additive to be incorporated into resinous polymers that stabilizes against decomposition by light.

The term "resinous polymers" here includes polyolefins, such as high and low pressure poly-

ethylene, polypropylene, polybutadiene, polyisoprene, polystyrene and the like. Olefin copolymers, such as ethylene-propylene copolymers, Styrene-butadiene copolymers, acrylonitrile - butadiene - styrene copolymers, polyurethanes and the like, and these resinous polymers can be used in the form of fibers, films or otherwise designed objects, latex, foams and the like.

It has now unexpectedly been found that the above-mentioned piperidine-N-oxyl-spiro-hydantoine an exceptionally high degree of stabilizing effect on resinous polymers against Exert photodecomposition as well as that they show a low thermal sublimation and in the resinous Polymers do not noticeably discolour.

The piperidine-N-oxyl-spiro-hydantoins of the above formula (I) are new, not previously used in the art Links. These pipes idin-N-oxyl-spirohydantoine can be manufactured conveniently and advantageously

(a) by treating a piperidine-spiro-hydantoin compound of the formula

C-

-N
C.

H
H ₃ C

H ₃ C

(H)

I.
H

R ₂ '

wherein R ₁ 'and R _{2 can be the} same or different and represent lower alkyl groups or together with the carbon atom to which they are bonded, a 5- and 6-membered saturated homocyclic ring or a grouping of the formulas

CH., CH ₃

N-O-

or

Form CH ₃ CH ₃ , with a peroxide or

(b) by reaction of a piperidine-N-oxyl compound the formula

H ₃ C

(III)

■ -5

wherein R ₁ and R _{2 have} the meaning described above, with an alkali metal cyanide and ammonium carbonate.

In the above formula (I), the groups R ₁ and R _{2 can} each be represented by the following groups: methyl, ethyl, n-propyl, isopropyl, η-butyl, isobutyl, hexyl, octyl, decyl and dodecyl.

Representative examples of piperidine-N-oxylpiro-hydantoins (1) that can be used in the present invention include the following hydantoins

U ^ -Triaza ^ J ^ -tetramethyl ^ -dioxo-

spiro [4,5] decane-8-oxyl,
Cyclohexane-l-spiro ^ '- io' ^ '- dimethylpiperidine-

1'-oxyl) -4'-spiro-5 "-hydantoin, (2,2,6,6-tetramethylpiperidin-1-oxyl) -4-spiro-2 '- (6', 6'-dimethylpiperidine-1 -oxyl) -4'-spiro-

5 "hydantoin,

40

spiro [4,5] decane-8-oxyl,
i

45

2,4-dioxo-spiro [4,5] decane-8-oxyl, 1,3,8-triaza-7,7-diisobutyl-9,9-dimethyl-

2,4-dioxo-spiro [4,5] decane-8-oxyl and cyclopentane-1-spiro-2 '- (6', 6'-dimethylpiperidine-1 '-oxyl) -4'-spiro-5'-hydantoin.

Preparation of U ^ -Triaza ^ J ^ -tetramethyl-2,4-dioxo-spiro [4,5] decane-8-oxyl

To a solution of 20 g of 1,3,8-triaza-7,7,9,9-tetramethyl-2,4-dioxo-spiro [4.5] decane in 80 ml of acetic acid were 0.5 g of ethylenediaminetetraacetic acid, 0.4 g of sodium tungstate and then added 40 ml of 30% hydrogen peroxide. The resulting mixture was stirred at room temperature for 7 days. then the reaction mixture was concentrated under reduced pressure to give the residue so obtained a saturated aqueous solution of potassium carbonate was added, and then this became resulting mixture stirred at room temperature for 1 hour. After that, the deposited became crystalline Substance obtained by filtration, washed with water and then recrystallized from aqueous ethanol, ' thereby obtaining the desired product which melts at? 3I "C (with decomposition).

Analysis values for C ₁₁ H ₁₈ O ₃ N ₃ :

Calculated ... C 54.98, H 7.55, N 17.49%;
found .... C 55.19, H 7.67, N 17.45%.

The electron spin resonance spectrum (in tetrahydrofuran) of the product thus obtained showed a strong triplet of hyperfine coupling of constant 15.3 Oersted, which was split up by the interaction of the unpaired electron spin with the Nuclear spin of the N atom in the piperidine ring. This result evidently proves the presence a stable N-oxyl free radical in the product.

Preparation of cyclohexane-l-spiro-2 '- (6', 6'-dimethylpiperidin-l'-oxyl) -4'-spiro-5 "-hydantoin

A solution of 1.1 g of 1-aza-2,2-dimethyl-'t-oxospiro [5.5] -undecane-1-oxyl, 0.4 g of sodium cyanide and 2.5 g of ammonium carbonate in 20 ml of 50% strength aqueous ethanol was stirred for 7 hours at 50 to 6O ⁰ C. Then the reaction mixture was ice-cooled and the precipitated crystalline substance was separated by filtration, washed with water and then recrystallized from aqueous ethanol to obtain the desired product, which melts at 282 to 283.5 ° C.

Analysis values for C ₁₄ H ₂₂ O ₃ N ₃ :

Calculated ... C 59.98, H 7.91, N 14.99%;
found .... C 59.79, H 7.82, N 15.18%.

The piperidine-N-oxyl-spiro-hydantoine of the above formula (I) can pass into the resinous polymer various techniques commonly used in the art can be incorporated. For example, can the dry stabilizer in the form of a powder can be admixed with the resinous polymer, or it can be a suspension or emulsion of the resinous polymer with a suspension or emulsion of the stabilizer according to the invention are mixed.

The amount of piperidine-N-oxyl-spiro-hydantoin used in the resinous polymer can be vary within wide limits, for example in the case of polyolefins in concentration ranges of about 0.01 to 2.0 percent by weight, and preferably about 0.05 to 0.2 percent by weight. In the case of polyurethane the stabilizer in concentration ranges from about 0.01 to 10 percent by weight, and preferably in concentration ranges from about 0.05 to 5 weight percent applied. These concentrations are based on the weight of the polymer used.

The piperidine-N-oxyl-spiro-hydantoine (I) can be used alone or in combination with other additives can be used, as with other stabilizers, fillers, pigments and the like. If necessary, can be a combination of 2 or more piperidine-N-oxyl-spiro-hydantoins (I) apply.

In the examples, all parts stated are to be understood as parts by weight, unless otherwise is said.

example 1

In a mortar, 0.25 parts of the stabilizer were added to 100 parts of polypropylene, as was the case with the Table I below can be seen, intimately mixed.

The resulting mixture was preheated to 215 ° C. for 2 minutes under a pressure of 10 kg / cm ² and then pressure-melted into films of 0.5 mm thickness at 215 ° C. under a pressure of 150 kg / cm ² for 0.5 minutes.

Thereafter, all of the films produced in this way were tested for their "embrittlement time" under ultraviolet radiation at 45 ° C using an apparatus described in Japanese Industrial Standard JIS-L-1044-3-8 is being investigated

Table I. stabilizer

Piperidine-N-oxyl-spiro-hydantoine according to the invention

2,4-dioxo-spiro [4,5] decane-8-oxyl ..

Cyclohexane-1-spiro-2 '- (6', 6'-dimethylpiperidin-1 '-oxyl) -4'-spiro-5 "-hydantoin

(2,2,6,6-Tetramethylpiperidin-1-oxyi) -4-spiro-2 '- (6', 6'-dimethylpiperidinl-oxyl) ~ 4'-spiro-5 "-hydantoin

Commercially available stabilizers 2- (2'-Hydroxy-5'-methyl-phenyI) -

benzotriazole

2,2'-dihydroxy-3,3'-di-tert-butyl-5,5'-dimethyldiphenyl-methane

Without stabilizer

Example 2

A low molecular weight polymer with terminal hydroxyl groups (manufactured by Reaction of 2 moles of f-caprolactone diol with a

Embrittlement

time (hours)

400

360

440

15th

20th

80

100 40 molecular weight of 1000 with 1 mole of 2,4-tolylene diisocyanate; 200 g) was the polymerization with 46 g of methylenebis (4-phenyl isocyanate) at 90 ° C during subjected to one hour to produce a prepolymer.

The prepolymer thus obtained was dissolved in 740 g of dimethylformamide at room temperature. then a further amount (50 g) of dimethylformamide, which contains 1.7 g of water, was added 2x1 to the resulting solution, added. After sufficient stirring, a viscous solution was obtained, which could be used in 5 portions of roughly the same amount was shared in each case. The portions of the solution were intimately mixed with 1 percent by weight, based on the polymer, of the stabilizers according to the following tables. Every Portion of the stabilized solution was spun into 280 denier thread through a conventional one Wet spinning process in water at 40 ° C.

The threads thus obtained were then examined for their light resistance. It became a test procedure applied, in which the threads were exposed to ultraviolet radiation at 55 "C for 25 hours, using an apparatus described in JIS-L-1044-1959. The tensile strength and the elongation of the filaments before and after exposure to ultraviolet rays were measured with the help of a normal thread tensile tester »Tensilon« (portable thread tensile tester, manufactured and sold by Toyo Sokuki K.K., Japan). The specific loss of tensile strength and the specific elongation loss was determined as the difference between the values before and after respective exposure to light. The color that forms during and / or after exposure to violet was visually observed and door every thread recorded.

Table II

stabilizer

Piperidine-N-oxyl-spiro-hydantoin according to the invention

2,4-dioxospiro [4.5] decane-8-oxyl ... cyclohexane-1-spiro-2 '- (6', 6'-dimethylpiperidine-1 '-oxyl) -4'-spiro-5 "-hydantoin

Commercially available stabilizers 2- (2'-Hydroxy-5'-methylphenyl) -

benzotriazole

2-Hydroxy-4-n-octoxybenzophenone ..

Without stabilizer

Specific tension loss (% j specific
Elongation loss (%)

48 50

85 47
45

81

color

unchanged
unchanged

Yellowing
Yellowing

Brown color

From the above results it follows that the piperidine-N-oxyl-spiro-hydantoine (I) according to the invention have a high Maintain tensile strength and elongation and that they are also effective in terms of Prevents discoloration in the resinous polymers after exposure to light.

Claims (1)

Claim: Use of a piperidine-N-oxyl-spiro-hydantoin of the general formula (I) wherein R ₁ and R _{2 can be the} same or different and represent a lower alkyl group or, together with the carbon atom to which they are bonded, a 5- or 6-membered saturated homocyclic ring or the grouping of the formula