DE1290720B - Ultraviolet light protection agent for organic polymers c - Google Patents

Description

The protection of polymers and macromolecular products against the effects of ultraviolet light by incorporating an ultraviolet light absorbing substance into the mass is a standard practice in the plastics industry. An important class of compounds that has found quite wide use for this purpose are certain substituted o-oxybenzoph.enones. In order to be useful in special formulations, the UV absorber must, for. B. have certain solubility properties, etc., which make it compatible with the compound in which it is incorporated. It must have strong UV absorption in the region where it is most favorable. It must be difficult to volatilize so that it is not lost from the mass through evaporation; it should be stable to UV light and therefore not easily decomposed; it should be easy to incorporate into the mass or easy to apply to the mass after formation and it should not give the mass any inherent color. Various substances have met many of these needs, but there is still a need for UV absorbers which meet all of these needs. This is especially true for certain masses _r the basic reactive centers or base before systems such as Super polyamide (nylon), wool fibers, silk, etc., included.

Certain oxybenzophenones are useful in such systems, but there are disadvantages especially by the yellowing of the mass. An example of this is the yellowing of nylon due to the application of 2-oxy-4-methoxybenzophenone, a compound that in many cases is an excellent UV absorber.

In addition, the usual UV absorbers are also sensitive to a change in pH and therefore cannot be used with resins that polymerize under basic conditions or, as a yellow color develops here too.

It used to be common practice to bring UV absorbers into resinous substances by using them incorporated into the monomer during the polymerization step or after polymerization and before pressing became. Such a process is with a synthetic polymer, but not with one natural polymers, such as in wool or silk, possible.

The subject of the invention is the use of 0.05 to 5 percent by weight, based on the end product, of a carboxybenzophenone of the general formula

55

60

Both phenyl radicals as substituents are alkyl, alkoxy groups with up to 18 carbon atoms, chlorine or can contain hydroxyl groups, as a protective agent against UV light for natural and artificial organic polymers, especially those containing trivalent nitrogen. This UV Absorp

tion agents can also be applied to fibers that contain trivalent nitrogen, such as Nylon or wool, from dyebaths in the acidic range. Come as alkyl substituents for example in question methyl, ethyl, propyl, isobutyl, butyl, amyl, isoamyl, heptyl, methylhexyl, Ethylhexyl, lauryl or octadecyl radicals. Any alkoxy groups can also be present such as methoxy, ethoxy, butoxy, isobutoxy, isoamyloxy, lauryloxy or octadecyloxy groups. The following typical compounds can be used according to the invention:

2-oxy-2'-carboxybenzophenone, 2-oxy-5-chloro-2'-carboxybenzophenone, 2-oxy-4-methoxy-2'-carboxybenzophenone, 2,4-dioxy-2'-carboxybenzophenone, 2-oxy- 4-methoxy-3 ', 4', 5 ^/ , 6'-tetrachloro

2'-carboxybenzophenone, 2-oxy-4-butyl-2'-carboxybenzophenone, 2-oxy-5-methyl-2'-carboxybenzophenone.

It is most surprising that the carboxybenzophenones give such excellent results are compatible with the polymeric compositions and do not cause yellowing. Until now it was believed that the presence of acidic groups, such as the carboxyl group, gives the product undesirable solubility and would impart acidic properties, since the products are more hydrophilic and water-soluble and therefore would be less soluble in the plastic. It was also expected that these carboxybenzophenones, since they are acids, they would be even more pH sensitive than the much less acidic ones phenolic compounds of the benzophenone series, which were previously used as UV absorbers. In addition, the use of carboxyl derivatives was not expected to cause yellowing could prevent that with nitrogen-containing polymers such as nylon, wool, etc., with ordinary UV absorbers was observed.

It is an advantage of the present invention that as the pH increases, the compounds do not cause yellowing. The dyeings on nylon and wool are also completely colorless. It is a Another advantage of the present invention is that the compounds, although they have increased water solubility and have reduced hydrocarbon solubility in contrast to ordinary UV absorbers have higher solubility in the resin composition. They also have UV absorbers superior properties in terms of light stability, absorption maximum, absorption capacity at the wavelength of maximum absorption, low volatility. An advantage of the present Another invention is that both wool and nylon are dyed using the same method can, although common in the usual dyeing of fibers, be completely different Process to use for dyeing nylon and wool.

The superior properties of the UV absorbers used here can be seen from a comparison can be seen with commercially available UV absorbers. It becomes 2-oxy-4-methoxy-2'-carboxybenzophenone compared to the commercial UV absorber 2 - oxy - 4 - methoxybenzophenone. The following are their absorption properties

(in toluene solution) compared:

λ, ηηχ (toluene

Absorption at l _max ■ . ■
Absorption at 380 ηΐμ
Absorption at 400 ηΐμ

2-oxy-4-meth-

oxy-2'-carboxy-

benzophenone

320 ηΐμ 34.8 0.02 0.03

2-oxy-4-meth-

oxybenzo

phenone

328 ηΐμ 40.5 0.12 0.08

The absorption properties of the carboxyl compound change in an aqueous solution in one wide pH range, as shown below:

PH 315 ηΐμ
315 ηΐμ
355 ΙΒμ Absorption at λ, _ικ , _χ 2.1
7.0
12.1 35.7
35.0
29.2

At a pH of 12.1, the carboxyl compound showed very little color and has an absorption at 400 mμ of 6.1, while even at a pH of 9.8, 2-Qxy-4-ri: ^ri .: cxybenzophenone shows much more staining, wocdi f. has an absorption at 400 mμ of 21.5. The 2-oxy-4-methoxy-2'-carboxybenzophenone also has a much greater light stability than the corresponding non-carboxylated benzophenone, as can be seen from the following tests on cellulose acetate and in nylon:

Light stability in ⁰ Z _{0 of} the original amount of UV absorber *) (loss of obligation **)
considered)

2-oxy

4-methoxy

2'-carboxy

benzophenone

2-oxy

4-meihoxybenzo diienone

In cellulose acetate
after 100 hours of exposure 98 95

after 500 hours of exposure 91 82

In nylon

after 100 hours of exposure 93

*) Remainder in ° ' _o = D ₀ ZD ₁₀₀ , where D ₀ and D _{100 are} the optical densities at the absorption maximum at 0 and 100 hours of exposure.

• **) Weight loss of 2-oxy-4-methoxy-2'-carboxybenzophenone at 84 ^C C: 0 mg / cm ² per hour. Weight loss of 2-oxy-4-methoxy-benzophenone at 84 C: 0.18 vag / cm ¹ per hour.

The coloring of the obtained by coloring nylon with various UV absorbers Product also shows considerable advantages of the compounds prepared according to the invention, as shown in FIG is evident from the following values:

Color of the fabric

2-oxy-4-methoxy-2'-carboxy-

benzophenone colorless

2-oxy-4-methoxy-2'-carboxy-3 ', 4', 5 ', 6'-tetrachlorobenzo

phenone colorless

2-Oxy-4-methoxybenzophenone ... Light yellow 2,2'-Dioxy-4-methoxybenzophenone yellow

The carboxy derivatives of 2-oxybenzophenones, as used in the present invention, can by conventional synthesis methods getting produced. Suitable substituted benzoyl chlorides or phthalic anhydrides are used with suitably substituted alkoxybenzenes condensed and the o-alkoxy group is dealkylated. if a benzoyl chloride is used, it must be an o-methylbenzoyl chloride, the o-methyl group is later oxidized to the 2'-carboxyl group. The condensation is a possible synthesis Phthalic acid in a Friedel-Crafts reaction with the appropriately substituted alkoxybenzene is much better suitable. The o-benzoylbenzoic acid obtained is often the desired UV absorber.

A variety of organic polymeric substances can be protected in accordance with the invention. In addition In the first place, natural and synthetic, nitrogenous fibers, such as natural fibers, are included the wool and silk and the synthetic super polyamides, such as the various types of nylon, e.g. B. Polyadipic acid - hexamethylene diamide and polyomega-aminocaproic acid amide. They also include a number of very important synthetic polymers, the trivalent nitrogen in the polymer Contain structure, such as the polyacrylamides and polyacrylamides substituted on nitrogen, the urea-formaldehyde resins and the corresponding Derivatives of thiourea, ethylene urea, etc. Also the various melamine-formaldehyde resins belong to this and also various other aminoplasts, such as the formaldehyde triazinones.

The above-mentioned organic polymers are preferred because they are present

J5 of trivalent nitrogen in the polymeric backbone apparently with yellowing that occurs with use common UV absorber occurs, is related; but other polymers can also be used can be easily and advantageously protected. For some of them, basic conditions are used in the Polymerizations that would cause yellowing were used, but most of the following The advantage of the carboxybenzophenones and the fact that they are completely colorless is the advantage of polymers increased compatibility of increased light stability, etc. The following other polymers can, for. B. the following are used: polyesters, polyvinyl chlorides, polyvinyl acetates and mixtures thereof, polyalkyl acrylates, glyceride oil-modified alkyd resins, polyacrylonitrile and its copolymers, super polyesters, polystyrenes, polyolefins, such as polyethylene and polypropylene, and epoxy resins.

The UV absorbers according to the invention can be used in the polymerization mixture with the monomers incorporated and so inserted into the polymers in situ as they are formed. The UV absorbers can also be incorporated into the polymers by various methods after the polymerization, customary methods are grinding or mixing into powdery substances or simple addition to the liquid polymers. A special method is the process of coloring polymer fibers with UV absorbers. This process is important as it is for natural and synthetic polymers, such as wool and silk, and also nylon, can be used. It is important as the incorporation of the carboxybenzophenones in such nitrogenous fibers,

either by installation, e.g. B. during the spinning of nylon, or by dyeing the fibers, a significant protective effect on the tensile strength of fibers exposed to ultraviolet light will have.

In the dyeing process, the oxy-carboxybenzophenone is at a suitable pH in Brought aqueous dispersion. Such a dispersion can be achieved by adding a solution of the benzophenone in an alcoholic or other hydrophilic solvent to water or through Acidification of an aqueous solution of a salt of carboxybenzophenone can be prepared. In each If so, the dispersion would then be made sufficiently acidic. It will have a pH of no more than 7 needed to maintain substantivity on the fibers, and a pH below 5 is particularly beneficial. A pH of around 4.5 gives the best results. The fiber then becomes that produced Dyebath added and agitated in it while the dyebath is at a temperature above 65 ° C is held. Temperatures closer to the boiling point are preferred (usually around 87 ° C) to give better depletion of the dyebath.

After 30 days of exposure to Arizona sunlight, untreated nylon had lost half its tensile strength while nylon containing about 1.6% UV absorber (4-methoxy-2-oxy-2'-carboxybenzophenone) based on fiber weight , had only lost about ^x / 4 of the tensile strength. In the following examples, parts always mean parts by weight, unless otherwise stated.

example 1
Application to nylon by the dyeing process

A dye bath is prepared by dissolving 0.050 g (1% of the fiber weight) of 2-oxy-4-methoxy-2-carboxybenzophenone in 5 ml of 95% ethanol and adding this solution to 200 ml of water at 88 ^: C. A piece of nylon fabric weighing 5 g is added to the bath at 88 ° C. and stirred for 10 minutes. Dyeing is continued at this temperature with occasional stirring for an hour. The pH of the bath is 4.5. The samples are removed and dried. Analysis of the liquids indicated that the spun nylon picked up 72% of the UV absorber. After a wash test, 86% of the UV absorber remained on the towel. The UV absorber did not impart a yellow color to the nylon.

Reflectance measurements in the UV range with untreated nylon and nylon with different Absorbents was colored, gave the following results:

'Sample 420 ma 400 Ιϊΐμ 380μ 360 my. 340 ΓΠμ Untreated nylon
2-oxy-4-methoxy-2'-carboxybenzo-
nhenon 78.0
73.2
73.0
74.0
58.0
23.0 74.0
65.0
64.0
67.0
42.0
20.0 65.0
42.0
41.0
40.0
28.0
13.5 40.0
13.0
13.0
11.0
12.0
8.0 25.0
4.5
4.5
4.5
6.0
5.0 2,4-Dioxy-2'-carboxy-benzophenone ...
2'-oxy-4'-methoxy-2-carboxy-
3,4,5,6-tetrachlorobenzophenone
2-oxy-4-methoxybenzophenone
2,2-dioxy-4'-methoxybenzophenone

• Example 2
Application to wool after the dyeing process

A solution of 0.05 g of 2-oxy-4-methoxy-2'-carboxybenzophenone in 50 ml of alcohol becomes a hot one (90 ° C) dye bath, which is buffered at a pH value of 4 and contains 5 g pieces of wool flannel, added. The addition is carried out in the course of 50 minutes. A similar procedure is performed using 0.2 g of UV absorber carried out. In no case is the wool given a color. The amount of UV absorber on the wool is measured spectrophotometrically.

Reflectance measurements are made with the above samples as well as with a sample obtained by a dispersion staining process stained with 2,2'-dioxy-4-methoxybenzophenone.

sample

⁰ 0 absorbent on the fiber 420 ma

^q ο reflection at
400 mu. 380 m <i

340 mn

Wool, untreated

2-oxy-4-methoxy-2'-carboxybenzo-0.68

* "- phenone 1.4

2,2'-Dioxy-4-methoxybenzophenone 2.5

B e i s ρ ί e 1 3 melamine resin compositions

A melamine-formaldehyde resin syrup is made by the following process: It becomes a Mixture of 2279 parts of water. 1000 parts 49

49
49

33

43

42
41.8

16.2

35.2

3l; 5

6.5

26th
13th

37% formaldehyde solution and a sufficient amount of sodium hydroxide to set a
pH of 8.6. To this mixture
1197 parts of melamine are added. the
The mixture is heated and stirred and the reaction mixture is gradually heated to 98-102.degree.

The mixture is then stirred at this reflux temperature until 4 drops of the reaction mixture, when added to 25 ml of water at OC, give a blue solution with a blue mist. The resinous syrup is then rapidly cooled to about 65 ° C. and concentrated in vacuo until syrup is obtained which contains 66% solids. A sufficient amount of commercially available alpha cellulose and zinc stearate is then added to this syrup so that a mass is formed which, calculated on the dry state, contains about 30% filler material and 70% resin. The mixture is then ^{spread out, dried at 70 °} C. and ground sufficiently finely. This mixture is then pressed into small blocks. It shows significantly better resistance to yellowing on exposure to UV light and on heat treatment than a similar plate made without a UV absorber.

Example 4
Polyvinyl resins

A copolymer of vinylidene chloride and vinyl chloride is placed in a heated compounding press together with 2-oxy-4-methoxy-2'-carboxybenzophenone in a weight ratio of 200: 1 brought. The press produces a thin, transparent sheet suitable for packaging. A comparison sheet is made by simply turning off the benzophenone derivative feed. In the case of intensive exposure to UV light over a longer period of time, polymer samples turn out to be that have this particular addition, as significantly more resistant than samples of the comparison sheet.

Example 5
Polystyrene mass

A solution of 0.2 parts by weight of 2-oxy-4-methoxy-3 ', 4', 5 ', 6' - tetrachloro -T- carboxybenzophenone in admixture with ring-substituted Styroien containing 65% p-methylstyrene, 33% o -Methylstyrene and 2% m-methylstyrene contain. This substance is block polymerized by initially

3 days at 100 ° C is heated and the temperature

Is increased to 230 ^{0 C for 4 days.} The polymer obtained is rolled with 1.0% titanium dioxide ^{pigment onto rollers heated to 165 °} C. in order to thoroughly disperse the pigment and also to remove unreacted monomer. The rolled product is then granulated and shaped ^{at 200 ° C. by the injection molding process.} On prolonged UV exposure, it is observed that the rolled product turned only slightly yellow compared to an article made in exactly the same way but with the benzophenone compound omitted.

Claims (1)

Claim: Use of 0.05 to 5 percent by weight, based on the end product, of a carboxybenzophenone the general formula OH ^ COOH Both phenyl radicals as substituents are alkyl, alkoxy groups with up to 18 carbon atoms, chlorine or can contain hydroxyl groups, as a protective agent against UV light for natural and artificial organic polymers. 909511/1691