DE1244399B - Usually solid, pigmented polyolefin molding compounds - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

C08f

German class: 39 b -22/06

Number: 1244 399

File number: P 25743 IV c / 39 b

Filing date: September 26, 1960

Opened on: July 13, 1967

The invention relates to stabilizing polyolefins against deterioration by UV light.

A known deficiency of polyolefins is that they are resistant to prolonged exposure to the weather, especially the UV component of sunlight, are sensitive by causing their deterioration suffer mechanical and physical properties and color instability.

It was found that pigmented polyolefin compositions under the same conditions are even shorter Have a lifespan as unpigmented, light-stabilized polyolefins. Such pigmented polyolefin compositions Most organic stabilizers, the unpigmented polyethylene protect against the effects of light, not in a satisfactory manner against degradation by the action of light protection. For example, salicylates and alkoxyhydroxybenzophenones are used as stabilizers for Polyethylene ineffective, which pigments from the in "Plastics Technology", Vol. 3, p 633 (1957), described Kind or other similar pigments used for polyolefins.

It is known (US Pat. No. 2,582,510) to use polyethylene against the deterioration in the Storage as well as under the influence of high temperatures and the weather, especially against the Oxidation by atmospheric oxygen under the action of ultraviolet light, by joint To stabilize the addition of sulfur and a dialkyldithiocarbamate of zinc, copper, lead or selenium. These stabilizers can also be added to molding compositions made of polyethylene, the inorganic pigments or contain organic dyes. However, the desired high stabilizing effect is achieved only achieved with the joint addition of sulfur and the dialkyldithiocarbamates mentioned. Will the If sulfur is omitted, the stabilizing effect is far less. In addition, copper dithiocarbamate is prone to to discolor the polyolefins stabilized with it, so that they become unsightly.

In addition, zinc dialkyldithiocarbamates can only be added to homopolymers or copolymers of ethylene for the purpose of stabilizing against the action of the mechanical Processing heat occurring known (British patent specification 779 807). However, these stabilizers are not effective enough for adequate stabilization against exposure to light.

According to the invention, to stabilize pigmented molding compositions made of polyethylene or polypropylene, nickel dithiocarbamates are used which have a high stabilizing effect against normally solid, pigmented molding compositions
made of polyolefins

Applicant:

EI du Pont de Nemours and Company,
Wilmington, Del. (V. St. A.)

Representative:

Dr.-Ing. W. Abitz, patent attorney,
Munich 27, Pienzenauer Str. 28

Named as inventor:
John Brian Armitage,

Harold Clinton Barker, _

Wilmington, Del. (V. St. A.);

Gustav Daendliker, Riedt (Switzerland)

Claimed priority:
V. St. v. America September 28, 1959
(842 556)

distinguish ultraviolet rays and do not require the further addition of sulfur.

The invention relates to stabilized, normally solid, pigmented molding compositions made from polyolefins and a dithiocarbamate of a divalent metal with the characteristic that it is used as a stabilizer from 0.0005 to 2 percent by weight, based on the polyolefin, of a nickel dithiocarbamate of the general formula

N — C —S

-Ni

.2

contain, where R and R _{1 are} alkyl, aryl and / or aralkyl groups, optionally in a mixture with 0.001 to 1 percent by weight, based on the polyolefin, of a heat stabilizer known for polyolefins.

The nickel dithiocarbamate can be prepared according to known methods, for example those of C a ν e 11 and S u g d e η in »J. Chem. Soc ", 1935, p. 624, described methods. Preferred nickel dithiocarbamates to stabilize the polyolefin compositions are, for example, the dimethyl, diethyl, dipropyl, diisobutyl and higher molecular weight dialkyl, the diphenyl, ditoluyl and other diaryldithiocarbamates. These Stabilizers are added to the polyolefin in concentrations of at least 0.0005, preferably 0.5

709 610/592

up to 2 percent by weight, in particular from 0.75 to 1.5 percent by weight, based on the polyolefin, added. The stabilizers with substituents having longer hydrocarbon chains are im generally better compatible with the polyolefins than the stabilizers with the shorter chains.

When using the nickel dithiocarbamates according to the invention, due to the pale green color of the Nickel dithiocarbamates itself causes a very small change in the standard shade of the pigment to occur. However, this difficulty can easily be overcome by looking at the proportions of the various Pigments changes.

The molding compositions according to the invention are preferably also known heat stabilizers added, e.g. B. Salicylic acid octadecyl ester, N- (p-oxyphenyl) - morpholine, tri - tert.butyl - ρ - phenylphenol, 4,4'-thio-bis- (6-tert-butyl-m-cresol), 4,4'-butylidenebis- (6-tert-butyl-m-cresol), 2,2'-methylenebis (4-methyl-6-tert-butylphenol), dialkyl thiodipropionate and the stabilizers disclosed in U.S. Patent 2,519,755. These stabilizers can be found in Amounts in the range from 0.001 to 1.0 percent by weight, based on the polyolefin, are used.

The molding compositions can be prepared by z. B. processed the polyolefin and the auxiliaries on a rubber ^{grinder at 140 to 170 0} C, dissolves the auxiliaries in a suitable solvent such as acetone, hexane or benzene and sprayed the solution into a Banbury mixer containing the polyolefin.

The molding compositions according to the invention can be used for all common uses of polyolefin compositions be used, e.g. B. as foils, threads, rods, tubes and rods, especially for purposes where the product is exposed to the weather, especially to the action of UV light.

The following examples serve to further illustrate the invention, with parts and percentages, as in the rest of the description, based on the weight of the polyolefin. The auxiliary materials According to the examples are in the polyolefin on a two-roll grinder for 15 minutes at 160 ± 5 ° C ground in. Films (7.6 x 15.2 cm x 0.25 mm) molded from these compositions are then used as rapid weathering tests subject. In order to mimic the conditions prevailing in the open air, a

ίο Test device of the type »Atlas XW Weather-Ometer« filtered light on wet and dry cycles (18 minutes wet and 102 minutes dry) for exposure brought. The one obtained with the auxiliaries Stabilization is carried out with a polyethylene film that does not contain any stabilizer in a tensile test according to Elmendorf (according to ASTM test standard D 689-44) and in a melt index test (according to ASTM test standard D 1238-52), for which the abbreviations ELM and MI are used below

be ao. Occurs without additives and when exposed to weathering initially a decrease in the melt index due to crosslinking of the polyolefin. This is not generally undesirable when processing has already been completed. With progressive degradation on the other hand and the occurrence of a chain scission is an increase in the melt index along with a reduction in toughness (Elmendorf tensile test).

Table I shows the resistance of pigmented polyolefin compositions according to the invention (Examples 4, 6, 8 and 9) against discoloration and degradation once that of non-pigmented polyethylene, which is no Nickel dithiocarbamate contains (Examples 1 and 2), and on the other hand that of pigmented polyethylene (Examples 3, 5 and 7), which contains no nickel dithiocarbamate, compared. That in these The polyethylene used in the examples is a branched chain low density polyethylene.

Hi
Art fsstoff
Weight
percent Far
Art Table I. Without Be
ELM weather
MI 500pcs
Bewit
ELM unden
; erung
MI 1.66 74 1.02 81 1.89 1000 p
Bewit
ELM hours
learning
MI example Xa 0.2 material
Weight
percent 102
125 2.2
2.16 sprc
42 ) de
0.9 brittle brittle 79 1.75 brittle 5.8 1*
2 *
• X ₂
X ₃ ο, ι
1.0 } D - 81 2.5 brittle - - 3 * { Xi
Xa 1.0
0.1 } ^D 1.0 87 2.38 66 58 1.40 ** 4 { Xa
X ₃ 0.1
1.0 j _D 1.0 119 2.79 - - 5 * { Xi
Xa ι, ο
ο, ι 0.5 117 2.20 60 0.79 ⁶ { X ₂
X ₃ 0.1
ι, ο } There 1.0 94 2.74 - - 7 * { Xi
Xa 1.0
0.1 } D ₂ 0.1 114 2.42 73 1.58 8 y Xi
Xa 1.0
ο, ι } D ₃ 1.0 107 2.41 60 0.79 9 y 1.0

* Comparative experiment.
** 1250 hours of weathering.

Meanings of D, D ₁ , D ₂ , D ₃ , X ₁ , X ₂ and X ₃ for Table I: D = polychlorophthalocyanine,
D ₁ = titanium dioxide,

D ₂ = copper phthalocyanine - green tone,

D ₃ = red real pigment,

X ₁ = nickel dibutyldithiocarbamate,

X ₂ = 4,4'-thio-bis- (6-tert-butyl-m-cresol),

X ₃ = octadecyl salicylate.