CS265476B1 - Azodicarbonamide decomposition activator - Google Patents

Abstract

The azidicarbonamide decomposition activator for the production of lightweight polyvinyl chloride leatherette with a covering layer based on aromatic polyesterurethanes is composed of at least one substance from the group of potassium nitrite, sodium nitrite or ammonium nitrate and may additionally contain 10 to 80% by weight of potassium nitrate, sodium nitrate or a mixture thereof and optionally 25 to 50% by weight of water or 50 to 95% by weight of glycerin as a solvent, always based on the weight of the activator as a whole.

Description

The present invention relates to an azodicarbonamide decomposition activator, the most commonly used blowing agent for polyvinyl chloride pastes, polyolefins and elastomers. Azidocarbonamide decomposes at 200 to 220 ° C, which is too high for most applications. Therefore, the decomposition temperature of the azidocarbonamide is lowered by the addition of activators to the range of 160 to 170 ° C. In particular, compounds of the vicemoon metals, such as lead, cadmium and zinc, are used.

The bulk of the presently manufactured polyvinyl chloride leatherette consists of a polymeric cover layer based on aromatic or aliphatic polyester urethanes, a lightened plasticized polyvinyl chloride layer formed using azidocarbonamide decomposition activators, and a textile backing.

Despite the excellent physico-technical and aesthetic parameters of this type of leatherette, there were some reservations about their application in some areas. One of the causes of the less favorable assessment is the change in the properties of these materials over time, over long-term use or storage. These changes, such as the formation of a matt, non-slip coating on long-stored leatherette, a decrease or loss of cohesiveness of the layers, and a decrease in resistance to mechanical damage have often been attributed to plasticizer migration or even degradation. It has now been shown that the cause of this material aging is a specific type of degradation reactions in the aromatic polyesterurethane coating layer caused by polyvalent metal compounds which form the basis of all the azodicarbonamide decomposition activators hitherto referred to as kickers in PVC plastisol technologies.

It has been shown that these compounds diffuse to a large extent from the PVC layer to the polyurethane layer, and that the above reactions lead to a decrease in the molecular weight of the polymer and to the formation of low molecular weight substances causing the above mentioned negative phenomena. In addition, there is a gradual decrease or loss of strength and later also ductility of the polyurethane coating. In the extreme case, the degradation process results in a sticky mass that no longer exhibits elastic properties.

In addition to temperature, the speed of this process is influenced by the type of aromatic polysterurethane used, the type and concentration of the kicker used, and the gelatinization conditions used to produce the material. It has been found that even the top commercial aromatic polyurethanes recommended for PVC use are at the usual concentrations of the most used kicker and the usual gelatinization conditions, i.e. 3 min at 180 ° C, due to 70 ° C and relative humidity measurement at 25 ° C. 40%, which was used to accelerate the aging process, on a bilayer polyurethane-lightweight PVC to significantly decrease the strength of the separated polyurethane film after only one to two weeks, and that the decrease has a permanent character. After four weeks, the ductility of the polyurethane starts to decrease significantly.

These disadvantages are overcome by the activator according to the invention, which contains at least one of potassium nitrite, sodium nitrite and ammonium nitrate. The activator according to the invention may further comprise 10 to 80 wt. potassium nitrate, sodium nitrate or mixtures thereof, based on the total weight of the activator.

The activators are difficult to disperse in the plastisols and their efficacy in the blowing process has been shown to be dependent on the degree of this dispersion.

This drawback is overcome by the addition of 25 to 95 wt. % solvent, for example 25 to 50 wt. % water or 50 to 95 wt. glycerin, based on the total weight of glycerol; activator.

In contrast, the activator of the invention acts as a medium to fast kicker, but does not cause the degradation of the aromatic polyesterurethanes or is significantly slower in use.

The invention creates the preconditions for the full utilization of the excellent quality leatherette based on the combination of aromatic polyurethane - lightweight PVC layers and for their application even where they have failed so far because of their shorter lifetime eg in upholstery.

The method of application is further elucidated in the examples, from which the effects of the invention are apparent.

Example 1

A basic paste of composition was prepared using a quick mixer

PVC emulsion paste-forming 75 % by weight parts PVC micro-suspension paste-forming 25 % by weight. parts di-2-ethylhexyl phthalate 40 % by weight parts butylbenzylphthalate 35 % by weight parts di-2-ethylhexyl adipate 5 % by weight parts filler 5 % by weight parts azodicarbonamide 3 % by weight parts

About a quarter of the paste was mixed with four parts by weight of potassium nitrite. Using a three-roller friction, the activator was spread and finely dispersed in said portion of the paste, and then homogenized with the remainder of the base paste using a rapid mixer.

A film of 0.1 to 0.15 mm thickness was produced on the release paper by repeatedly applying three times and drying the commercial aromatic polyesterurethane (A) solution using a Werner-Mathis apparatus. This film was further overlaid on release paper with two layers of the above paste. The layer thicknesses were chosen such that the ratio of basis weight of polyurethane to PVC layers was the same as that of leatherette, i.e. ranged from 1: 5 to 1: 7 overall, and also the thermal gelling and lightening regime was the same as that of leatherette. A temperature of 180 ° C for three minutes resulted in a two-layer polyurethane-lightweight PVC in the Werner-Mathis. This bilayer was divided into two parts. The second part was exposed to a temperature of 70 + 1 ° C in a hot air oven with forced air circulation for 5 weeks. Since the separation of the polyurethane film from the expanded PVC layer was not successful due to the high cohesion of the two layers, the first part of the bilayer was removed immediately after gelation by the application of the expanded PVC using a splitting machine. only slightly affect the strength of the polyurethane film. The tensile strength of this film was 44 MPa and the bulk density of the expanded PVC layer was 430 kg / m. The strength of the polyurethane film obtained by the same process from a bilayer subjected to accelerated aging at 70 ° C was 39 MPa. On the other hand, when 1.75 parts by weight of a commercial liquid zinc-based kicker X was used instead of potassium nitrite, the tensile strength of the polyurethane after gelatinization was 40 MPa and after aging under the same conditions 23 MPa at a density of lightweight PVC layer 350 kg / m \ If the content of the same kicker was increased to 3.5 wt. parts, the strength of the poylurethane after gelation was 32 MPa and after aging under the given conditions 12 MPa at the density of the expanded PVC layer was 260 kg / m < 3 >

Example 2

According to the procedure of Example 1, 4 wt. parts of sodium nitrite. The resulting paste was applied to release paper and gelatinized at 180 ° C for 3 minutes in a Werner-Mathis apparatus to obtain expanded PVC with a density of 770 kg / m. When a gelatinization temperature of 190 ° C was used under otherwise identical conditions, the bulk density was 500 kg / IR.

Example 3

According to Example 2, a base paste containing 4 wt.% Azodicarbonamide as a decomposition activator was tested. parts of ammonium nitrate. The temperature of 180 ° C for 3 minutes resulted in a lightweight PVC of 315 kg / m 2 and at 185 ° C under otherwise identical conditions of 230 kg / m 2.

Example 4

According to the procedure of Example 1, the aging of commercial polyurethane B, characterized by moderate cohesion with softened PVC, in combination with a PVC base paste containing a 1.38 wt.% Azodicarbonamide decomposition activator was evaluated. parts by weight of potassium nitrite and 2.62 wt. parts of sodium nitrite. The strength of the polyurethane film which could be completely separated from the PVC expanded layer in the case of this polyurethane was 39 MPa immediately after gelation at 410 kg / m ^{3 of the} expanded layer and after accelerated aging described in Example 1 it was 37 MPa. In contrast, using 1.75 wt. parts of a commercial zinc-based kicker X obtained values of 35 MPa, 340 kg / m ³ and α

MPa. When using 3.5 wt. Values of 36 MPa, 230 kg / m and 7 MPa were obtained with the same activator X. When using 3.5 wt. Values of 34 cpa, 230 kg / m &^lt; ³ > and 13 cpa were obtained from parts of another commercial activator Y based on cadmium and zinc. Yet another commercial cadmium-zinc activator Z at the same concentration yielded 36 MPa, 245 kg / m ³ and 17 MPa. The process of preparing the paste with said mixture of nitrites was reproduced with the fact that the spreading of the activator with the paste on the three-cylinder was repeated 3 times. The test performed according to Example 2 at 180 ° C gave a bulk density of 295 kg / m ³ .

Example 5

According to Example 2, a base paste containing a 1.47 wt.% Mixture of azodicarbonamide was tested. % of sodium nitrite and 2.53 wt. parts of potassium nitrate. A temperature of 180 ° C for 3 minutes resulted in a density of lightweight PVC of 330 kg / m ³ and at 185 ° C under otherwise identical conditions of 260 kg / m 3.

Example 6

According to Example 2, a base paste containing a 0.90 wt% blend of azodicarbonamide was tested. parts of sodium nitrite and 3.10 wt. parts of potassium nitrate. A temperature of 180 ° C for 3 minutes resulted in a bulk density of 420 kg / m ³ and at 185 ° C under otherwise identical conditions of 350 kg / m ³ .

Example 7

According to Example 2, a base paste containing a mixture of 3.65 wt.% Azodicarbonamide was tested. parts by weight of potassium nitrite and 0.45 wt. parts of sodium nitrate. At a gelatinization temperature of 180 ° C a bulk density of 410 kg / m ³ was achieved and at 185 ° C under otherwise identical conditions 340 kg / m ³ .

Example 8

According to Example 2, a base paste containing a 3.18 wt.% Mixture of azodicarbonamide was tested. parts of ammonium nitrate with 0.82 wt. parts of sodium nitrate. A density of 320 kg / m ³ was achieved at a gelatinization temperature of 180 ° C and 260 kg / m ³ at 185 ° C.

Example9

According to the procedure of Examples 1 and 3, the aging of the aromatic polyurethanes A and B in combination with a base paste containing a mixture of 1.6 wt. parts by weight of potassium nitrite, 0.28 wt. % of sodium nitrate and 2.12 wt. parts of potassium nitrate. In the case of polyurethane A, the strength of the film separated from the expanded PVC layer immediately after gelation was 42 MPa, at a density of the expanded PVC layer 350 kg / m ³ and after the accelerated aging described in Example 1, it was 40 MPa. In the case of polyurethane

B values of 41 MPa, 430 kg / m and 39 MPa were obtained under otherwise identical conditions. Due to the different bulk density values obtained, as in Example 4, the paste preparation process was reproduced, resulting in a bulk density at 180 ° C of 280 kg / m ³ and at 185 ° C of 240 kg / m ³ after repeated spreading of the paste activator.

Example 10

According to Example 2, a base paste containing a 2.63 wt. parts by weight of ammonium nitrate, 0.65 wt. parts of sodium nitrate and 0.72 wt. parts of potassium nitrate. At a gelatinization temperature of 180 ° C a bulk density of 405 kg / m ³ was achieved, at a temperature of 185 ° C 310 kg / m ³ .

Example 11

A liquid azodicarbonamide decomposition activator composed of 4 wt.% Was gradually metered into the base paste of Example 1 with stirring in a rapid mixer. parts of potassium nitrite and 1.5 wt. parts of water. its dispersion was completed by further vigorous stirring for 5 minutes. The paste obtained was tested as in Example 2 except that the actual gelatinization of the paste was preceded by exposure to 100 ° C for 1 minute. A density of 390 kg / m ³ was achieved at 180 ° C, and 305 kg / m ³ at 185 ° C.

Example 12

A base paste containing a 1.38 wt.% Mixture of azodicarbonamide was prepared according to the procedure of Example 11. parts by weight of potassium nitrite 2.62 wt. parts of sodium nitrite and 3.5 wt. parts of water. The tests carried out according to Example 11 yielded a bulk density of 180 kg / m 2 for 180 ° C and 220 kg / m 3 for 185 ° C.

Example 13

A base paste containing an azodicarbonamide decomposition activator of 1.6 wt. parts of sodium nitrite, 0.28 wt. parts by weight of sodium nitrate, 2.12 wt. parts by weight of potassium nitrate and 3.5 wt. parts of water. According to the procedure of Examples 1 and 3, the aging of commercial aromatic polyesterutane B was evaluated except that the actual gelation of the PVC coatings was preceded by drying at 100 ° C. The tensile strength of the polyurethane separated immediately after gelation was 41 MPa at the density of the expanded PVC layer 240 kg / m @ 2 and after accelerated aging was 39 MPa. In addition, accelerated aging was evaluated in this case according to the so-called tropical test, ie 70 ° C at 95% relative humidity. Tensile strength of polyurethane B, separated immediately after gelation,

It was 35 MPa at a density of 230 kg / m and after four weeks of aging it was 31 MPa and after six weeks of aging it was 29 MPa. In contrast, when using 3 wt. parts of commercial zinc activator X were 32 MPa, 250 kg / m ³ , 3.3 MPa and 1.8 MPa. Furthermore, in this case, a leatherette having a common polyurethane B-based covering layer 35 µm thick was made and on one part a layer of expanded PVC was formed from the paste described above and on the other part from the below described paste containing 3 wt. The textile layer was also common to both parts.

These parts of the leatherette did not differ in thickness of 0.9 mm after gelation at 175 ° C for 3 minutes and the void size of the lightweight layer showed no significant differences. The leatherette was then exposed to the tropical test for 5 weeks. The portion of the sample where the activator of the invention was used exhibited a repeat bending resistance of greater than 100,000 cycles after this aging, while the other portion of the sample, produced using a commercial Zinc-based activator X, had a completely damaged coating after 5,500 cycles on the flexometer Bally.

Further, the preparation of the above-described paste was repeated several times and the tests of Example 11 yielded a bulk density at 230 ° C to 250 kg / m 2 at 180 ° C.

Example 14

According to Example 11, a base paste containing a 3.18 wt.% Mixture of azodicarbonamide was tested. parts by weight of ammonium nitrate, 0.82 wt. parts of sodium nitrate and 2 wt. parts of water. A density of 440 kg / m ³ was achieved at 180 ° C and 310 kg / m ³ at 185 ° C.

Example 15

According to Example 11, a base paste containing a 2.63 wt.% Mixture of azodicarbonamide was tested. parts by weight of ammonium nitrate, 0.65 wt. parts by weight of sodium nitrate, 0.72 wt. part of potassium nitrate and 2 wt. parts of water. A density of 450 kg / m ³ was achieved at 180 ° C and 360 kg / m ³ at 185 ° C.

Example 16

According to Example 11, a base paste containing a 4 wt.% Mixture of azodicarbonamide was tested. parts of ammonium nitrate and 4 wt. parts of glycerin. A density of 270 kg / m ³ was achieved at 180 ° C, and 215 kg / m ³ at 185 ° C.

Example 17

According to Example 11, a base paste containing a 6 wt.% Azodicarbonamide decomposition activator was tested. parts of ammonium nitrate and 15 wt. part glycerin. A density of 230 kg / m ³ was achieved at 180 ° C and 220 kg / m ³ at 185 ° C.

Example 18

According to Example 11, a base paste containing an additional 10 wt. parts of another filler and as activator a mixture of 2 wt. parts of ammonium nitrate and 40 wt. parts of glycerin.

A density of 270 kg / m ³ was achieved at 180 ° C and 230 kg / m ³ at 185 ° C.

Example 19

Following the procedure of Example 11, a base paste containing a 3.18 wt.% Mixture of azodicarbonamide was prepared. parts by weight of ammonium nitrate, 0.82 wt. parts of sodium nitrate and 4 wt. parts of glycerin. According to the procedure of Examples 1 and 3, the aging of commercial aromatic polyesterurethane B in combination with said paste was evaluated. The tensile strength of the polyurethane separated immediately after gelation was 36 MPa □

at a density of the expanded PVC layer of 270 kg / m and after accelerated aging according to Example 1, the tensile strength of the separated polyurethane was 27 MPa.

Claims (3)

An azodicarbonamide decomposition activator in the manufacture of expanded polyvinyl chloride leatherette with an aromatic polyesterurethane-based coating, characterized in that it consists of at least one of potassium nitrite, sodium nitrite and ammonium nitrate. 2. Activator according to claim 1, characterized in that it contains up to 80% by weight of potassium nitrate, sodium nitrate or a mixture thereof, based on the weight of the activator. 3. Activator according to claim 1, characterized in that it contains 25 to 50% by weight of water or 50 to 95% by weight of glycerine, based on the weight of the activator.