WO2020109270A1

WO2020109270A1 - Phosphine derivatives as oxygen scavengers

Info

Publication number: WO2020109270A1
Application number: PCT/EP2019/082506
Authority: WO
Inventors: Claudio Adolfo Pietro Tonelli; Floryan De Campo; Paul RAGOGNA; Kaijie NI
Original assignee: Solvay Specialty Polymers Italy S.P.A.
Priority date: 2018-11-27
Filing date: 2019-11-26
Publication date: 2020-06-04

Abstract

The present invention relates to novel compounds which are the reaction product of at least a trivalent P containing molecule and a Si containing molecule, which are useful as oxygen scavengers.

Description

Phosphine derivatives as oxygen scavengers

Technical Field

[0001] This application claims priority to EP N°18208688.4 filed on November 27, 2018, the whole content of this application being incorporated herein by reference for all purposes.

[0002] The present invention relates to new chemical compounds comprising phosphorus atoms and silicon atoms having a good capacity to scavenge oxygen. The invention also relates to a method for their manufacture and their use as oxygen scavengers and anti-oxidant stabilizers in various applications including protection of oxygen sensitive materials such as food, electronics and chemicals (pharmaceuticals, polymers etc.), as processing aids (preventing oxidative damage during manufacturing and/or processing) and to extend materials shelf life.

Background Art

[0003] Oxygen scavengers are chemicals which are able to prevent oxidative degradation of sensitive materials by collecting, removing or neutralizing the oxygen (O2). A typical application of oxygen scavengers is found in the food industry where the presence of oxygen in a packaged food is often a key factor in limiting the shelf life of a product. More broadly oxygen scavengers find application in any situation where traces of oxygen may degrade a sensitive material such as e.g. pharmaceuticals and vitamins, medical diagnostic kits, artworks, electronics etc. Notably oxygen scavengers find application also as processing aids to prevent oxidative damage of materials during manufacture or processing, for example during processing of polymers with oxidizable groups.

[0004] Several methods are known for the inclusion of oxygen scavengers into packaging and closed environments. Often oxygen scavengers can be added directly to the material to be preserved, for example edible oxygen scavengers such as ascorbic acid can be added within food. In some cases oxygen scavengers can be added to the container of the material to be preserved (e.g. the food packaging). In this case the oxygen scavenger can be added directly within the bulk of the container material or in films or coatings within the container. Alternatively or in addition it can be included in inserts such as packets or sachets within the same package together with the material to be protected.

[0005] Examples of chemicals conventionally used as oxygen scavengers are iron powder, ascorbic acid, photosensitive dyes, enzymes (such as glucose oxidase and ethanol oxidase), unsaturated fatty acids (such as oleic, linoleic and linolenic acids etc.), rice extract or immobilized yeast on a solid substrate. Iron powder, typically in sachets, is widely used for food protection, but its use as an additive in chemical processing such as polymer manufacture, is strongly limited because the iron particles may trigger unwanted chemical reactions.

[0006] Trivalent Phosphorus based oxygen scavengers of low molecular weight (molecules) or high molecular weight (polymers) have been disclosed in the art. Some organophosphorus compounds are efficient hydroperoxide decomposers under the processing conditions of polyolefins. Hindered aryl phosphites and phosphonites are used industrially in polymer processing. Due to the versatility of their reactions, trialkyl phosphines are also promising candidates for polyolefin stabilization. However low molecular weight phosphines are too volatile to be used in polymer processing when resistance to high temperature (i.e. > 200 °C) is required. The use of phosphorous-rich polymers is less explored: their use is described as homogeneous catalysts and oxygen scavengers (Polymer Vol. 38 No. 2, pp. 317 323, 1997 Elsevier Science Ltd) however this structure contain PEG chain that is known to be very sensitive to thermal

degradation/oxidation so that the use of these polymers at high

temperature is not possible.

There is a continuous interest in the industry in the development of new materials which can be used as oxygen scavengers, and thermal stabilizers, so to provide materials which can be employed in a broader range of applications and conditions, in particular for polymer processing there is a need for materials that combine high efficiency in oxygen adsorption and high thermal stability (200°C minimum) in order to make their use possible under the typical polymer processing conditions (200- 300°C).

Summary of invention

[0007] The present invention relates to novel compounds which are obtained from the reaction of molecules comprising one or more trivalent P (Phosphorus) atom and molecules comprising one or more Si (silicon) atoms containing also unsaturations as described below. Such compounds can be obtained for example as linear, branched or networked polymers or as oligomers, and can be used as such or functionalized as customary in the polymer industry. The resulting compounds find application as oxygen scavengers, preservatives and anti-oxidant stabilizers for applications in all industries where conventional oxygen scavengers are used. Compounds according to the invention can be used as pure compounds e.g. in films, layers or in particulate form, or as additives to other materials to provide protection from oxidative damage to the materials themselves or to products contained in packaging made of that material. Compounds according to the invention are surprisingly stable at high temperatures while maintaining their oxygen scavenging abilities. This makes them particularly useful in high T applications such as additives during polymer processing.

[0008] In a first aspect, the present invention relates to a compound which is the reaction product of at least a P containing molecule and a Si containing molecule, wherein said P containing molecule comprises at least one trivalent P atom and at least two P-H bonds on the same or on different trivalent P atoms, and wherein said Si containing molecule comprises at least one Si atom and at least two unsaturations selected from the group consisting of double carbon-carbon bonds, triple carbon-carbon bonds and triple carbon-nitrogen bonds, with the provision that double carbon-carbon bonds are counted as one unsaturation and triple carbon-carbon and carbon-nitrogen bonds are counted as two unsaturations.

[0009] In a second aspect, the present invention relates to a method for

manufacturing such a compound.

[0010] In a third aspect, the present invention relates to a method of processing a melted polymer in the presence of a compound as described above which acts as an oxygen scavenger.

[0011] In other aspects the present invention relates to the use of such a

compound as an oxygen scavenger or oxygen barrier material in packages or compositions. The Applicant has surprisingly found that compounds according to the invention have good O2 scavenging properties.

Brief description of the figures

[0012] Figure 1 shows a TGA (Thermogravimetric analysis) for a compound of the invention in comparison with two other P containing compounds not according to the invention. .

Description of embodiments

[0013] As said, in a first aspect, the present invention is directed to a compound which is the reaction product of at least a P containing molecule and a Si containing molecule, wherein said P containing molecule comprises at least one trivalent P atom and at least two P-H bonds on the same or on different trivalent P atoms, and wherein said Si containing molecule comprises at least one Si atom and at least two unsaturations selected from the group consisting of double carbon-carbon bonds, triple carbon- carbon bonds and triple carbon-nitrogen bonds, with the provision that double carbon-carbon bonds are counted as one unsaturation and triple carbon-carbon and carbon-nitrogen bonds are counted as two

unsaturations.

[0014] In the P containing molecule the P-H bond is the reactive moiety.

According to the invention the P containing molecule must have at least two P-H bonds and these two bonds can be on the same or on different trivalent P atoms.

[0015] For example in the P containing molecule“phosphine” with formula PH3 we can find 3 P-H bonds on the same atom which are all reactive for the purpose of the invention. Similarly in a primary alkyl phosphine which has general formula R-PH2, two P-H bonds on the same P atom can react according to the invention. Also included among the P containing molecules according to the invention are multifunctional phosphines such as for example:

PH2-R-PH2

which has four P-H reactive moieties.

[0016] Each P-H moiety in the P containing molecule is able to react with one double bond saturating it or with one triple bond converting it to a double bond.

[0017] During the reaction the P-H bond is broken and the P atom binds directly to the unsaturation according to the following scheme (shown for a double C-C bond):

The same reaction scheme applies, mutatis mutandis, for a triple bond: when the P-H moiety reacts with an unsaturation which is a triple C-C or C-N bond. In this case the triple bond is saturated in two subsequent steps reacting with two different P-H moieties, typically from two different P containing molecules: in a first step, a first P-H moiety adds to a triple bond between two atoms, atom 1 (A1) and atom 2 (A2), partially saturating it to a A1-A2 double bond, wherein the P atom from the first P-H moiety binds to A1. In a second step another P-H moiety, typically from a different P containing molecule, adds to the A1-A2 bond fully saturating it, typically the P atom from the second P-H moiety binds to A2 for sterical reasons, but depending on the specific reaction it may also bind to A1. In the appropriate conditions which will be detailed below, the reaction between the P-H moieties and the unsaturations is complete. As both the P containing molecule and the Si containing molecule contain each at least two reactive groups the reaction may lead to the formation of polymeric chains. The molecular weight of the compounds of the invention is not a critical factor as both low molecular weight oligomers and high molecular weight polymers would function as oxygen scavengers according to the invention. Depending on the number of reactive groups on each molecule the resulting compound can be a liner, branched or networked polymer. In a preferred embodiment at least one of the P containing molecule or Si containing molecule has at least 3 reactive groups (reactive groups being P-H moieties in the P containing molecule or unsaturations in the Si containing molecules). In this case a networked polymer can be formed wherein one or more covalent bonds are formed between different polymeric chains as a consequence of the reaction of the P-H moieties unsaturations as described above. As it will be shown below it was surprisingly found that compounds according to the invention in the form of a networked polymer have an increased thermal stability and can be used as oxygen scavenger at higher temperatures.

[0018] It was surprisingly found that compounds obtained according to the

invention have excellent properties, in particular they are able to capture oxygen and, particularly in the case of networked polymers, have an exceptional thermal stability, thus being able to capture oxygen even at very high temperatures.

[0019] Without being bound by theory, it is believed that each of the trivalent P atoms can quickly trap one oxygen atom (forming a P=0 double bond where the trivalent P atom oxidizes to P(V)). The role of the silicon moiety is likely to facilitate the oxidation of the P atom as it increases the permeability/affinity for the O2 in the compound.

[0020] The P containing molecule may preferably be selected from phosphine

(PH3) and organophosphorus compounds such as primary and secondary phosphines of multifunctional phosphines (i.e. phosphines with more than one trivalent P atom) as long as they have at least two P-H bonds on the same or different P atoms. Irrespective from the mechanism of action it has been observed that the capacity of the compounds of the invention to scavenge O2 (measured as oxygen uptake, see experimental section below) is directly linked to the concentration of trivalent phosphorus in the molecule. It is therefore preferred that the concentration of trivalent P in the compound is as high as possible. Therefore preferred P containing compounds are those having a high concentration of trivalent P such as PH3, primary phosphines R-Phh wherein R is a C1-C10 moiety, and multifunctional phosphines with a high P concentration. Most preferred P containing molecules are PH3 and primary phosphines R-Phh wherein R is a C1-C10 moiety, in particular monoisobutylphosphine. In general P containing molecules having more than 1 mole of trivalent P for 160 grams of molecule are preferred as they will bring a higher amount of P in the resulting compound.

[0021] The Si containing molecule for use in the present invention can be

selected from silanes, siloxanes as well as oligomers and polymers thereof, provided they comprise the required unsaturations.

Preferred silanes have the general formula:

wherein each of Ri, R₂, R3 and R₄ can be H or a saturated or insaturated group, wherein R₁-R₂-R3 and R₄ as a whole include at least 2 unsaturations. By“group” is meant a straight-chain or branched C atom chain which may be substituted or unsubstituted, saturated or insaturated. The“group” may be substituted by from 1 to 3 substituents which may be the same or different, preferably selected from halogen (preferably chlorine or fluorine), hydroxy, amino, but is preferably unsubstituted. Preferably such groups have from 1 to 8 carbon atoms, more preferably from 1 to 6 carbon atoms, and most preferably 1-4 carbon atoms. Most preferred silanes are tetraallylsilane and diallyldimethylsilane.

[0022] Other preferred Si containing molecules are siloxanes and siloxane

oligomers comprising the required unsaturations. In particular siloxanes and siloxane oligomers where each Si is bonded to an insaturated group as defined above. Among these, particularly preferred are

divinyltetramethyldisiloxane, 2, 4, 6, 8 tetramethyl-2, 4,6,8- tetravinylcyclotetrasiloxane and octavinylotasilasesquioxane.

[0023] Since each P-H moiety reacts with one unsaturation, those Si containing molecules having the highest concentration of unsaturations (as number of unsaturations per mole, counting 1 the double bonds and 2 the triple bonds) will be preferred. Specifically Si containing molecules having at least 1 moles of unsaturations for 100 grams of molecule are preferred.

[0024] In general, the molar ratio of P to Si atoms in the compound is between 0.5 and 2, preferably between 0.9 to 1.1 , most preferably between 0.95 and 1.05.

[0025] Also encompassed by the present invention are those compounds that are the reaction product of multiple reactive species as defined above, i.e. being obtained from a reaction mixture where more than one type of P containing molecule and more than one type of Si containing molecule are present.

[0026] Also encompassed by the present invention are those compounds which are the reaction product of P containing molecules and Si containing molecules as defined above together with other reactive species which are not in accordance with the definition of P containing molecule and Si containing molecule as provided above. In all cases the resulting compound will be able to act as oxygen scavenger based on the amount of trivalent P contained therein.

[0027] Without being bound by theory it is believed that the addition reaction of trivalent phosphorus to the unsaturations is a radical mediated addition wherein, upon hydrogen abstraction, the phosphinyl radical adds to the unsaturation forming a carbon centred radical which subsequently abstracts a hydrogen atom from a nearby phosphine molecule, thus leading to propagation of the reaction. The reaction is in general quantitative in the appropriate conditions.

[0028] Compounds according to the invention can be manufactured dissolving said Si containing molecule and said P containing molecule in organic solvents such as toluene, dichloromethane or THF, then adding a radical initiator, which can be chemical, for example azobisisobutyronitrile (AIBN), or UV light. The reaction might be conducted at T from ambient to 70- 80°C, temperatures between 60 and 85°C were found to be the most effective.

[0029] Compounds according to the invention can be used as oxygen

scavengers, thermal stabilizers, preservatives. They can be used per se as blocks, pellets, powders, films or intermixed with the substance to be protected from oxidative attack, e.g. mixed with foods or polymers. As it will be shown in the experimental section below, compounds according to the invention, especially when in the form of a networked polymer, are stable and still capable to act as oxygen scavengers at high temperature. This makes them ideal as antioxidant additives for polymer processing, especially for those polymers which are processed at high T such as fluoropolymers, aromatic polymers and in general polymers with T or melting points above 200°C or 300°C. A polymer can be processed in melted form adding a compound according to the invention to the melt, this can reduce oxidative degradation of the polymer.

[0030] The compounds of the invention can also be used to prevent oxidative degradation of a material by packaging said material within an enclosed space together with a material according to the invention. The material of the invention may be enclosed in a sachet, in a compartment which is in communication with the material or can be coated or printed onto the inner side of the package or dispersed within the material.

[0031] Should the disclosure of any patents, patent applications, and publications which are incorporated herein by reference conflict with the description of the present application to the extent that it may render a term unclear, the present description shall take precedence.

Experimental Section

[0032] Materials

[0033] All solvents were purchased from Caledon and dried using an MBraun controlled atmosphere solvent purification system and stored in Straus flasks under an N2 atmosphere or over 4 A molecular sieves. The following reagents were used:

• PH3 - from Solvay Specialty Polymers Italia S.p.A.

• Monoisobutylphosphine (BuPhte) - from Solvay Specialty Polymers Italia S.p.A.

• Phenylacetylene (Alkyne) - from Sigma Aldrich

• 2, 4, 6, 8-tetramethyl-2, 4, 6, 8-tetravinylcyclotetrasiloxane (SiO-4) - from Alfa Aesar,

• Octavinyloctasilasesquioxane (SiO-8) - AB PharmaTech., LLC,

Tetraallylsilane (Si-4) - from Sigma Aldrich

• Diallyldimethylsilane (Si-2) - from Sigma Aldrich,

• Divinyltetramethyldisiloxane (Si-2-O) - from Sigma Aldrich

• 1 -hexene - from Alfa Aesar,

• Bromoethane - from Alfa Aesar

• Phenylbis(2, 4, 6-trimethylbenzoyl)phosphine oxide - from Sigma

Aldrich

were all used as received

• Azobisisobutyronitrile (AIBN) was purchased from Sigma Aldrich and recrystallized from methanol.

[0034] Structural formulas for the Si containing compounds used for the synthesis of the novel compounds of the invention were as follows:

[0035] Methods

[0036] All manipulations were performed in a nitrogen filled MBraun Labmaster dp glovebox or by using standard Schlenk techniques. NMR

Solution state nuclear magnetic resonance (NMR) spectroscopy was conducted on a BRUKER 400 MHz spectrometer.

Solid-state NMR spectroscopic experiments were conducted on Varian INOVA 400 MHz at a spin rate of 9300 Hz and referenced using an external standard ((NH4)3Rq4; dR = 0).

A high intensity single arc mercury lamp (23.3 mW) was used as the light source for photopolymerization. Thermal gravimetric analysis (TGA) on a Q600 SDT TA Instruments was used to measure onset decomposition temperatures with a ramp rate of 20°C and perform oxygen uptake experiments under controlled conditions. A TA Q20 differential scanning calorimeter (DSC) was used to determine glass transition temperatures (T_g) with a ramp rate of 40°C per minute. TA Universal Analysis software was used to analyse the thermal data.

[0037] Synthesis examples

(all structures have been confirmed with ³¹ P and ³¹P{¹H} NMR)

Example 1 (comparative) - Synthesis of Alkyne-BuPH2

Phenylacetylene (0.57 g, 5.55 mmol) and monoisobutylphosphine (0.50 g, 5.55 mmol) were loaded into a pressure tube. A solution of AIBN (0.18 g, 1.1 mmol) in toluene (5 ml_) was added to the mixture. The pressure tube was heated to 70°C for 24 h. An orange colour solution was obtained. The volatiles were removed in vacuo to give an orange oil. Yield: 1.01 g. See below, reaction scheme 1 product on the left. [0038] Example 2 (comparative) - Synthesis of Alkyne-PH3:

Phenylacetylene (1.50 g, 14.7 mmol) and AIBN (0.24 g, 1.47 mmol) were dissolved in toluene (3 ml_) in a vial. The vial was loosely capped and transferred into a Parr reactor. The pressure vessel was purged with N2 gas (x 3) and PH3 gas (* 1). The pressure vessel was then charged with PH3 (80 psi) and heated to 70°C for 24 h. The excess PH3 gas was incinerated off under controlled conditions in a fume hood before the Parr reactor was opened inside a glovebox. A dark brown solution was obtained. The volatiles were removed in vacuo pumped off to give a brown oil.

See reaction scheme 1 product on the right.

Reaction scheme 1

[0039] Example 3 (Inventive) - Synthesis of S1O-4-PH3

2, 4, 6, 8-tetramethyl-2, 4, 6, 8-tetravinylcyclotetrasiloxane (SiO-4) (3.50 g, 10.2 mmol) and AIBN (0.17g, 1.02 mmol) were dissolved in toluene (6 ml_) in a long glass insert which is fitted into a Parr reactor. The pressure vessel was purged with N2 gas (* 3) and PH3 gas (* 1). The pressure vessel was then charged with PH3 gas (80 psi) and heated to 70°C for 12 h. The excess PH3 gas was incinerated under controlled conditions in a fume hood before the Parr reactor was opened inside a glovebox. A glassy solid was obtained, which was ground using a mortar and pestle. The ground solid was leached overnight in dichloromethane. The supernatant was decanted. The solid was washed with dichloromethane and dried under vacuum to give a colorless transparent solid. Yield: 4.49 g. Reaction scheme 2

[0040] Example 4 (Inventive) - Synthesis of Si08-PH₃

Octavinyloctasilasesquioxane (SiO-8) (0.78 g, 1.23 mmol) and AIBN (0.02 g, 0.123 mmol) were dissolved in tetrahydrofuran (18 ml_) in a long glass insert which is fitted into a Parr reactor. The pressure vessel was purged with N₂ gas (^c 3) and PH3 gas (^c 1). The pressure vessel was then charged with PH3 gas (80 psi) and heated to 70°C for 12 h. The excess PH3 gas was incinerated under controlled conditions in a fume hood before the Parr reactor was opened inside a glovebox. A liquid was obtained. The volatiles were removed in vacuo to give a solid. The resulting solid was washed with dichloromethane and dried under vacuum to give a pale orange solid. Yield: 0.6 g.

Reaction scheme 3

[0041] Example 5 (Inventive) - Synthesis of S1-4-PH₃

Tetraallylsilane (Si-4) (2.00 g, 10.4 mmol) and AIBN (0.17g, 1.02 mmol) were dissolved in toluene (6 ml_) in a long glass insert which is fitted into a Parr reactor. The pressure vessel was purged with N₂ gas (^c 3) and PH3 gas (x 1). The pressure vessel was then charged with PH3 gas (80 psi) and heated to 70°C for 12 h. The excess PH3 gas was burned off under controlled conditions in a fume hood before the Parr reactor was opened inside a glovebox. A brown glassy solid was obtained, which was ground using a mortar and pestle. The ground solid was leached overnight in dichloromethane. The supernatant was decanted. The solid was washed with dichloromethane and dried under vacuum to give a brown solid. Yield: 3.07 g.

Reaction scheme 4

[0042] Example 6 (Inventive) - Synthesis of S1-2-PH₃

Diallyldimethylsilane (Si-2) (2.50 g, 17.8 mmol) and AIBN (0.29g, 1.78 mmol) were dissolved in toluene (6 ml_) in a long glass insert which is fitted into a Parr reactor. The pressure vessel was purged with N2 gas (*

3) and PH3 gas (* 1). The pressure vessel was then charged with PH3 gas (80 psi) and heated to 70°C for 12 h. The excess PH3 gas was incinerated under controlled conditions in a fume hood before the Parr reactor was opened inside a glovebox. A jellylike brown/orange solid was obtained, which was ground using a spatula. The resulting solid was leached overnight in dichloromethane. The supernatant was decanted. The solid was washed with dichloromethane and dried under vacuum to give a brown jellylike solid. Yield: 3.23 g.

Reaction scheme 5 [0043] Example 7 (Inventive) - Synthesis of Si20-PH₃

Divinyltetramethyldisiloxane (Si-2-O) (2.50 g, 13.4 mmol) and AIBN (0.22g, 1.34 mmol) were dissolved in toluene (6 ml_) in a long glass insert which is fitted into a Parr reactor. The pressure vessel was purged with N2 gas (^c 3) and PH3 gas (x 1). The pressure vessel was then charged with PH3 gas (80 psi) and heated to 70°C for 12 h. The excess PH3 gas was incinerated under controlled conditions in a fume hood before the Parr reactor was opened inside a glovebox. A dark brown liquid was obtained. See scheme 6.

[0044] Example 8 (Inventive) - Synthesis of S1-2-O-PH3

Same result as from example 7 has been obtained by performing the same reaction with UV activation at room temperature and using CH2CI2 as solvent, see scheme 6:

Sl*0 Si_jOPIt_j

Reaction scheme 6

[0045] Example 9 (Inventive) - Synthesis of Si20-BuPH₂ at a molar ratio of 3 to 2.

Si-2-0 (1.18 g, 5.4 mmol) and monoisobutylphosphine (0.322 g, 3.6 mmol), a molar ratio of 3 to 2, were loaded in a vial. A solution of phenylbis (2, 4, 6-trimethylbenzoyl) phosphine oxide (0.009 g, 0.022 mmol) in dichloromethane (1 ml_) was added to the mixture to give a pale yellow liquid. The vial was sealed and irradiated with ultraviolet light for one hour. The volatiles were removed to give a colorless slight viscous liquid. Yield: 1.42 g. See scheme 7-B.

[0046] Example 10 (Inventive) - Synthesis of Si20-BuPH₂ at a molar ratio of 2 to 3.

The same procedure was followed as in example 9, but the molar ratio of Si-2-0 and Monoisobutylphosphine was 2 to 3. See scheme 7-A. Reaction scheme 7

[0047] Example 11 (Inventive) - Synthesis of c-SiO-4-PH₃

1-Hexene (0.80g, 9.5 mmol) and AIBN (0.10 g, 0.61 mmol) was added to a suspension of SiO-4-PH3 (0.82 g) in toluene (8 ml_). The mixture was heated to 70°C for 17 h to give a yellow suspension. The suspension was left to sit for 1 h. The supernatant was decanted. The resulting solid was washed with dichloromethane and dried under vacuum to give a fine white powder. Yield: 0.81 g.

Reaction scheme 8

[0048] Oxygen Uptake measurement

General procedures for oxygen uptake experiments

Polymer samples were dried under vacuum at 100°C for overnight before they were subjected to oxygen uptake experiments. Approximately 0.007 g of milled sample/oil was placed in an alumina cup and exposed to nitrogen/air (100 mL/min) under controlled conditions as detailed in the experimental conditions of each test.

[0049] Table 1 shows oxygen uptake results after 180 min at 100°C exposed to air, shown as % weight increase. Table 1

A test repeated at 50°C for longer times (31 hours) showed for the Ex. 11 sample an oxygen uptake close to its max theoretical limit indicating that all trivalent P can participate in the oxygen uptake reaction.

[0050] Table 2 shows effect of time and T on oxygen uptake of S1O-4-PH3 (Ex. 3)

Table 2

Data from this table show how the kinetic of oxygen uptake is strongly influenced by the temperature and that compounds according to the invention perform very well at higher T such as 200°C.

[0051] Table 3 shows oxygen uptake for several materials of the examples after 10 hours at different temperatures.

Table 3

[0052] The results shown in tables 1-3 show that the Si containing compounds have a much higher ability to scavenge oxygen than the reference compounds.

[0053] Table 4 shows the results of oxygen uptake of SiO-4-PH3for 10 hours at 200°C after permanence under N2 at 200 and 300 °C respectively for 10 minutes and 12 hours.

Table 4

Follow oxygen uptake @ 200 ^°C T Time (h) Weight (%) Weight O_exp

(^°C) under N2 remained (%) (%)

200 0.17 99.5 106.2 6.7

300 0.17 98.4 104.3 5.9

200 12 98.5 104.9 6.4

300 12 96.9 102.2 5.3

Data in Table 3 show how compounds according to the invention fully maintain their Oxygen Uptake capacity even after permanence at 300°C. Finally the graph in Fig. 1 shows a TGA (Thermogravimetric analysis) for SiO-4-PH3 compared with the Alkyne P compounds of comparative Examples 1 and 2. Results show how compounds according to the invention are thermally stable until well above 400°C while other P based oxygen scavengers start decomposing well before 300°C.

Claims

Claim 1. A compound which is the reaction product of at least a P

containing molecule and a Si containing molecule, wherein:

- said P containing molecule comprises at least one trivalent P atom and at least two P-H bonds on the same or on different trivalent P atoms,

- said Si containing molecule comprises at least one Si atom and at least two unsaturations selected from the group consisting of double carbon- carbon bonds, triple carbon-carbon bonds and triple carbon-nitrogen bonds, with the provision that double carbon-carbon bonds are counted as one unsaturation and triple carbon-carbon and carbon-nitrogen bonds are counted as two unsaturations.

Claim 2. A compound according to claim 1 which is an oligomer or a polymer.

Claim 3. A compound according to claim 1 or 2 wherein said P containing molecule has at least 3 of said P-H bonds and/or wherein said Si containing molecule has at least 3 of said unsaturations.

Claim 4. A compound according to claim 3 which forms a networked polymer.

Claim 5. A compound according to any preceding claim wherein said P

containing molecule is selected from phosphine (PH3), and organophosphorus compounds.

Claim 6. A compound according to claim 5 wherein said P containing

molecule is selected from PH3, primary phosphines and secondary phosphines

Claim 7 A compound according to any preceding claim wherein said P

containing molecule has at least 1 mole of trivalent P every 160 grams of molecule.

Claim 8. A compound according to any preceding claim wherein said Si containing molecule has at least 1 mole of unsaturations in every 100 grams of molecule.

Claim 9. A compound according to any preceding claim wherein the molar ratio between trivalent P and Si is in the range of 0.5 to 2, preferably of 0.9 to 1.1.

Claim 10. A compound according to any preceding claim wherein said Si

containing molecule is preferably selected from silanes or polysiloxanes

Claim 11. A compound according to claim 10 wherein said Si containing

molecule is is a polysiloxane oligomer with 2-20 Si atoms, more preferably a cyclic or polyciclic oligomer, even more preferably 2,4,6,8-tetramethyl-2,4,6,8- tetravinylcyclotetrasiloxane.

Claim 12. A method for making a compound according to any preceding claim said method comprising the steps of:

i) dissolving said Si containing molecule and said P containing molecule in an organic solvent, preferably selected from toluene, dicloromethane and THF, ii) providing a radical initiator, preferably UV light or azobisisobutyronitrile (AIBN).

Claim 13. A method of processing a polymer in melted form said method

including adding to the polymer a compound according to claims 1-11 in order to reduce oxidative degradation of said polymer.

Claim 14. A method of preventing oxidative degradation of a material including packaging said material within an enclosed space, said enclosed space also containing a compound according to claims 1-11.

Claim 15. Use of a compound according to claim 1-11 as oxygen scavenger.