NO158220B - ORGANOTITANATES OR MIXTURES OF ORGANOTITANATES. - Google Patents

Description

The present invention relates to an organotitanate or mixtures of organotitanates which can be used as coupling agents between inorganic substances and polymers.

Inorganic substances have already for a long time been used as fillers, pigments, reinforcing agents and chemical reaction components in polymers. In general, these inorganic substances are hydrophilic, ie they are easily wetted by water or they can absorb water, but their compatibility with organic polymers is limited. Because of this limited compatibility, the inorganics' full potential of colour, enhancement or chemical reactivity cannot be fully exploited.

To avoid these difficulties, wetting agents have been used to reduce the tension in the interfaces, but the wetting agent also exhibits serious shortcomings. In particular, relatively large amounts are required in order to achieve sufficient wetting of the fine-grained, inorganic material. When wetting agents are used in large quantities, they noticeably reduce the properties of the final mixture. To solve this problem, coupling means have been developed. These can be divided into two main classes. Substances belonging to the first of these classes have the greatest application and are made up of trialkoxyorganofunctional silanes. Their activity is based partly on the chemical reaction between the alkoxy part and fillers and partly on the reaction between the organofunctional part and the polymer matrix. This creates a direct chemical bond between the polymer and the filler. However, silanes have certain shortcomings. Thus, in typical cases, they are highly flammable, difficult to process and not easy to mix in many polymer systems. When polymers do not contain functional groups or when the filler does not contain acidic protons, the silanes are often ineffective due to their inability to react. Thus, e.g. silanes ineffective for thermoplastic hydrocarbons and fillers such as carbon black, and to a large extent also calcium carbonate and sulphur.

The second class of coupling agents comprises organotitanates, which can be prepared by reacting tetraalkyl titanate with aliphatic or aromatic carboxylic acids. Of particular interest are di- and tri- and tri- alkoxy acyl titanates or certain alkoxy tri-acyl titanates. However, these titans have serious flaws. Thus, they have e.g. a tendency to split at temperatures often used in the manufacture of many polymers. They also tend to discolor certain inorganic substances used in polymer systems, and they are also incompatible with many polymer systems.

Organotitanate or mixtures of organotitanates according to the present invention are characterized in that the compounds individually correspond to the formula:

where R is a lower alkyl, lower haloalkyl or halogen substituted benzyl group, A is OCOZ where z is a vinyl, methyl-22 vinyl or aminophenyl group; -OSC₂R where R is a phenyl, aminophenyl, alkylphenyl or vinylcarbonylalkyl group; 3 3 -0P(0)(OR>2 where R is a long-chain aliphatic group; -0P(0)(OH)OP(O)(OR<4>)2 where R<4> is a long-chain aliphatic alkyl group; or OAr where Ar is a cumylphenyl group, x + z is 4;

x and z individually can be 1,2 or 3; provided that, when A is

-OS02R<2>; -OP(0)(OR<3>)2 or -OCOZ z must be 1.

Examples of specific ligands that can be represented by R are: methyl, propyl, cyclopropyl and cyclohexyl.

Examples of A-ligands that can be used in carrying out the invention include 11-thiopropyl-1-12-phenyloctadecylsulfone-, 2-nitrophenylsulfine-, di-2-omega-chlorooctylphenylphosphate-, diiso-nicotinyl pyrophosphate-, 2-nitro-3-iodo- 4-fluorothiophenoxy-, phenyl-sulfine-, 4-amine-2-bron-7-naphthylsulfone-, diphenylpyrophosphate-, diethylhexylpyrophosphate-, di-sec.-hexylph enylph osph at-, dilauryl-phosphate-, methylsulfone-, laurylsulfone- and 3-methoxynaphthalene-sulfine groups.

The aryl groups are i.a. phenyl and substituted derivatives thereof. Substituted aryl derivatives are i.a. toluyl, xylyl, pseudocumyl, raesityl, isodurenyl, durenyl, pentamethylphenyl, ethylphenyl, n-propylphenyl, cumyl.

Amine-substituted components are i.a. methylaminotoluene, trimethylaminophenyl, diethylaminophenyl, aminomethylphenyl, diaminophenyl.

Groups derived from aromatic carboxylic acids are also useful. Among these should be mentioned methylcarboxylphenyl, dimethylaminocarboxyltoluyl, laurylcarboxyltoluyl, nitrocarboxyltoluyl and aminocarboxylphenyl. Groups derived from substituted alkyl esters and amides of benzoic acid can also be used. Among these, aminocarboxylphenyl and methoxycarboxyphenyl should be mentioned.

Substituted natfill groups are i.a. nitronaphthyl.

Another material mixture according to the present invention comprises reaction products from the reaction between alkoxytitanium salts of the above-mentioned type and inorganic substances, especially where x in the above-mentioned formula is 3. The amount of reacted titanate is at least 0.01, preferably 0.1-5 parts and preferably 0, 2-2 parts per 100 parts inorganic, solid material. Optimum, necessary proportions are a function of the selected components, namely the solid, inorganic material and the alkoxytitanium salt in the same way as the degree of fine distribution, i.e. the effective surface area of the inorganic, solid material. Titanates react on the surface of the inorganic filler. The groups RO are split off and an organic, hydrophobic outer layer is formed on the inorganic, solid material. The unmodified, inorganic solid material is difficult to disperse in an organic medium because of the hydrophilic surface. The organotitanium compound can be mixed with the inorganic solid material in an organic medium (low molecular weight liquids or higher molecular weight polymers, solid matter). Alternatively, the organotitanate can first be reacted with the inorganic solid material in the absence of an organic medium and then mixed with the latter.

By means of the present invention, the dispersion of inorganic material in organic polymeric media is improved, and the following advantages are achieved: (1) improved rheology or higher content of dispersed material in the organic medium, (2) higher degree of reinforcement when using filler, which results in improved physical properties of the filled polymer, (3) more complete utilization of the chemical reactivity, whereby the required amount of the inorganic, reactive, solid materials is reduced, (4) more efficient use of pigment and opacifiers, (5) higher quantity ratio between inorganic and organic material in a dispersion and (6) shorter mixing times for obtaining a dispersion.

Moreover, the reaction according to the present invention with RO groups can be carried out without a reaction medium or in an organic medium, so that a liquid, solid or paste-like solid dispersion is obtained, which can be used for mixing into the final polymer system. Such dispersions are very stable, i.e. they have very little tendency to settle, separate or harden to a non-dispersible state when stored.

It can also be mentioned that the invention simplifies production

of inorganic dispersions in organic media by providing a means of eliminating solvents, reducing equipment costs and reducing the time and energy required for dispersing an inorganic solid, in a liquid or a polymeric, organic, solid material.

Use of the object of the invention results in the formation of a reinforced polymer, which has lower melt viscosity, improved physical properties and better pigmentation properties than previously known materials in this industrial area.

A product is thereby produced consisting of natural or synthetic polymers, which contain particulate or fibrous, inorganic materials, which reinforce, pigment or chemically react with the polymer to a product with improved physical properties, better processing properties and more efficient utilization of the pigment.

Among the advantages that can be achieved according to this embodiment, is the possibility to avoid volatile and flammable solvents and thus drying of the filler or recovery of the solvent. Furthermore, the formation of multi-molecular layers is reduced. Finally, it should be mentioned that the dispersions are not oxidising.

The inorganic materials can be in the form of particles or fibers of different shape and size, provided that the surfaces of the particles or fibers are reactive towards the hydrolyzable group in the organo-titanium compound. Examples of inorganic reinforcement materials are metals, clay, carbon black, calcium carbonate, barium sulphate, silicon dioxide, mica, glass and asbestos. Reactive inorganic materials are i.a. metal oxides of zinc, magnesium, lead and calcium and aluminium, iron filings and the like as well as sulphur. Examples of inorganic pigments are titanium dioxide, iron oxides, zinc chromate, ultramarine blue. In practice, the inorganic materials should not have a particle size of more than 1 mm and preferably the particle size should lie between 0.1 and 500 um.

It is important that the alkoxytitanium salt is properly mixed with the inorganic material, so that the latter's surface

responds adequately. The optimally used amount of alkoxytitanium salt depends on the desired effect, the available surface area and the amount of water bound in the inorganic material.

The reaction is facilitated by mixing under suitable conditions. Optimum results depend on the properties of the alkoxytitanium salt, namely whether it is a liquid or solid material, and its splitting and flash points. One must take into account, among other things, the particle size, the geometry of the particles, the specific gravity and the chemical composition. Also, the treated inorganic material must be carefully mixed with the polymeric medium.

The appropriate mixing conditions depend on the type of polymer, i.e. whether it is a thermoplastic or a thermosetting plastic, the chemical structure of the polymer, etc., which is obvious to the person skilled in the art.

When the inorganic material is pretreated with the organic titanate, the mixing can be carried out in any suitable intensive mixer, e.g. a Henschel mixer, a Hobart mixer or a Waring mixer. You can also use a hand-operated mixer. Optimum time and temperature are determined to achieve substantial reaction between the inorganic material and the organic titanate. The mixture is carried out under the conditions under which the organic titanate is present in liquid phase at temperatures below the decomposition temperature. Although it is appropriate that the main amount of the hydrolyzable groups react in this step, this is not essential in cases where the materials are later to be mixed together with a polymer, as the reaction can essentially be completed in this latter mixing step.

Polymer processing, e.g. mixing under strong force is generally carried out at a temperature well above the polymer's second transformation temperature, suitably at a temperature where the polymer has a low melt viscosity. The following should be mentioned as examples of optimal processing temperatures: For Ld polyethylene 170-230°C, for HD polyethylene 200-245°C, for polystyrene 230-260°C and for polypropylene 230-290°C. The person skilled in the art knows the temperature for mixing other polymers, and these temperatures can be found in the literature. A number of mixers can be used, e.g. twin roll mills, Banbury mixers, double concentric screw mixers, counter- and co-rotating twin screws and ZSK-type Werner, Pfaulder and Busse mixers.

When the organic titanate and the inorganic materials are dry-mixed, a complete mixing and/or reaction is not easily achieved, and the reaction can be substantially completed when the treated filler is mixed into the polymer. In this last step, the organic titanate can also react with the polymeric material if one or more of the groups present are reactive towards the polymer.

The treated filler can be incorporated into any conventional polymeric material, whether it is a thermoplastic or a thermosetting plastic, a rubber or a resin. The amount of filler depends on the polymer material, the filler itself and the properties desired for the final product. In general, it can be said that 10-500, preferably 20-250 parts of filler can be used per 100 parts polymer. The optimum amount can be easily determined by the person skilled in the art.

To further elucidate the invention, a

number of examples. In some of these examples, the number of ligands per molecule with a fraction. In that case, the structural formula represents a mixture of compounds, and the fraction is the average of the number of ligands in the mixture.

The following examples shall illustrate the invention.

Example A: Preparation of isooctyloxy-tri(cumylphenoxy)titanium A metal vessel covered with pyrex glass and equipped with a stirrer, internal heating and cooling devices, a steam condenser and a distillation trap is coated with 1 mol of isooctanol, 3 mol of mixed isomers of cumylphenol and 2 liters of mixed isomer xylene . The reaction mixture is stirred, blown through with nitrogen and 4.2 mol of sodium amide are added at such a controlled rate while cooling that the temperature of the reaction mass does not exceed approx.100°C. The ammonia formed as a by-product was blown off. The sodium amide treatment resulted in the formation of a heavy slurry which was refluxed for approx. 10 minutes in and for the removal of ammonia dissolved therein. The reaction mixture was then cooled to approximately 90°C and held at this temperature, while 1 mol of TiCl4 was added over 3 hours. After the TiCl 4 addition, the mixture was refluxed for 2 hours, cooled to about 100°C and filtered. The filter cake was washed with approximately 500 cm 3 xylene and discarded. The wash liquor was combined with the mother liquor and added to a still. Volatiles were removed to give a

residue (bottoms) with a boiling point of 10 mm Hg of over 150°C, a residue weighing approx. 800 g (this is over 95% of the theoretical). Elemental analysis of the residue, a dark red paste or a clear solid, gave results consistent with the formula (i-Cg H170)TiZTOC6H4C(CH3)2C6H573-

Example B: Preparation of (o-ClC6H4CH20) 1 2Ti(OS02C6H4NH2)2 8

In a reaction apparatus of the type described in ex. A, a solution of 1 mol of tetraisopropyl titanate in 2 liters of 2,6-dimethylnaphthalene was heated at 200°C. While this temperature is maintained for 2.5 hours, 1.25 moles of ortho-chlorobenzyl alcohol are added and immediately thereafter 2.8 moles of mixed isomers of aminobenzenesulfonic acid. The volatile components formed as a by-product (mainly methanol) were continuously removed by distillation. After the reaction mixture had cooled, the solid, gray substance was filtered off, washed with cyclohexane and dried in a vacuum oven, whereby approx. 565 g (82% yield) of a gray solid. This product was found to have an elemental analysis and an OH number consistent with the above formula.

In order to further illustrate the invention, examples of production methods are given in the following.

Example 1

A stockpile was prepared from the following components:

100 parts of chlorosulfonated, chlorinated polyethylene ("HYPALON 40"), 4 parts of finely divided magnesium oxide, 2 parts of low molecular weight polyethylene, 84 parts of calcium carbonate, 30 parts of a highly aromatic oil ("KENPLAST RD"), 3 parts of pentaerythritol 200 and 2 parts of an accelerator ("TETRONE A"). Four mixtures were tested. The first consisted of the above ingredients without further additions and served as a control sample. To the mixtures A, B and C, 1% (calculated on the amount of filler) of the following compound according to the invention was added:

All the mixtures were vulcanized at 152°C for 30 min. Table A shows the properties of the four compounds, as they were originally tested and after oven aging for 7 days at 121°C. The above-mentioned data clearly show, among other things, that the mixtures according to the invention have a lower modulus of elasticity than the control sample. In addition, the mixture C has a significantly better tear strength.

This is an advantage for polyvinyl chloride plastisols, because low viscosity means low energy consumption during processing. The reduced modulus of elasticity and the hardness of the mixture D are important, because in the past it has been necessary to use significant amounts of plasticizer to achieve such properties. Moreover, it is not possible with a plasticizer only to reduce the hardness and modulus of elasticity while maintaining a constant elongation at break.

Example 2

In this example, the applicability of the compounds according to the invention for modifying the properties of a flexible polyvinyl chloride mixture filled with calcium carbonate is shown. A control sample was prepared from 100 parts average molecular weight PVC resin, 1 part stabilizer ("DS 207"), 67 parts dioctyl phthalate and 50 parts finely divided calcium carbonate. In addition, five additional mixtures were prepared with the same composition as the control sample, but each of these was modified by being processed in a mixer at approximately 88°C for 3 min. with 0.5% by weight (calculated on the calcium carbonate) of the following compounds:

In the following table, the properties of the control sample and the mixtures according to the invention are summarized:

From the data summarized in table C, the advantages of the mixtures according to the invention appear quite clearly. The mixture E

shows a reduced modulus of elasticity and an increased elongation at break without deterioration of the tensile strength. The mixture H exhibits an improved elongation at break without loss of modulus of elasticity or hardness.

Example 2

To demonstrate the applicability of the invention for modifying the properties of styrene-butadiene copolymer rubber containing carbon black as filler, four mixtures were prepared. Two of these were used as control samples. The first, namely control sample 1, contained 100 parts of styrene-butadiene polymer,

50 parts carbon black ("HAF"), 4 parts zinc oxide, 2 parts sulphur,

1 part accelerator ("SANTOCURE NS"), 1 part stearic acid, 10 parts aromatic stretching agent in the form of oil and 2 parts of an antioxidant ("NEOZONE"). The second control sample essentially agreed with the first, and the only difference was that the carbon black was pre-treated with 1% Ca(OCl)2 at 38°C for 1 min. for improving the carbon black's ability to link with the titanate.

The mixture M was identical to control sample 1, but also contained 2 parts (i-C^H^O)^ gTi(OCgH^C(CH^)2^6H5^ 3.0*

Table D below shows the physical properties of the four mixtures, after vulcanization at 166°C for 30 min.

The advantages of the invention are apparent from the above data. It is to be noted that the mixture M exhibits improved modulus of elasticity and significantly reduced permanent elongation at break. This maintenance of dimensional stability upon breakage is a particularly favorable property when using the material, e.g. in shock absorbers.

Example 3

This example shows how the compounds according to the invention protect the polyethylene containing mineral fillers against attack by aqueous acid.

Two specimens with dimensions 25x75x3 mm were produced by injection molding in identically the same way, one of HD polyethylene containing 50% by weight magnesium silicate as filler, and the other of HD polyethylene containing 50% magnesium silicate which had been pre-treated at approx. 38°C with 1% by weight (CH30)x 2Ti(OS02C6 H4C12H25^ 2 8 ^'^ m^- n' ^ an intensive mixer. The thus obtained specimens were tested for their resistance to acid etching by placing a drop 8% hydrochloric acid was placed on each of the specimens which were then covered with a separate petri dish and aged in an oven at 38°C

for 2 4 hours. On visual inspection of the aged test specimens, it turned out that the one containing untreated magnesium silicate had significantly stronger discoloration than the other. Similar observations were made in parallel experiments, according to which the plastic was filled with the same content of a treated or untreated, anhydrous calcium sulphate instead of the treated or untreated magnesium silicate.

Example 4

In this example, the use of the following compounds according to the present invention is shown, namely: (R) (CH3O)Ti(OCOCH=CH2)3, (S) (i-C3H70)TiZOCOC(CH3)=CH273, (T) (i-C^O ) 2Ti (0S02 CH2CH2COCH=CH2) 2 and (U) (BrCH2CH20) TiZ"(OP (0) (OCH2CH=CH2) ^73 , as means of modifying the flexibility of polyester resins.

The blends were prepared from 100 parts of a cobalt-activated polyester resin ("GR 643"), 1 part methyl ethyl ketone peroxide, 60 parts high surface area calcium carbonate, and 0.3 part alkoxytitanium salt, all according to the table below.

Samples with dimensions 13x127x3 mm were cast and vulcanized at room temperature for 30 min. The cast specimens were tested, and the results obtained are summarized in table F.

From the above data it is clear that the organotitanate according to the invention gives the material improved bending properties.

When choosing the organotitanate compounds, the water content of the inorganic filler must be taken into account. If there is free or loosely bound water in the filler (as is the case, for example, with water-washed clays, hydrated silica, aluminum oxide gel, magnesium silicate, talc, fiberglass and aluminum silicate), pyrophosphate coupling agents are preferred. This is evident from the following example.

Example 5

A mixture of 30 parts by weight of kaolin (uncalcined, water-washed clay) and 70 parts of mineral oil was prepared. To portions of such leaves, 0.6 parts by weight of three organo-titanate compounds were added. The Brookfield viscosities of these dispersions are compared in Table G:

From the results summarized in the table above, where the first compound represents prior art, it is clear that each of the compounds reduces the viscosity of the dispersion of clay in mineral oil. However, it should be noted that isopropyl tri(dioctylpyrophosphato)titanate quite surprisingly gives a better viscosity reduction. This significantly reduces energy consumption when mixing the clay.

Example 6

The isopropyl tri(dioctyl pyrophosphate) titanate also reduces the viscosity of kaolin (uncalcined, water-washed, soft clay) dispersed in chlorinated paraffin. To prove this, a mixture of 30 parts by weight of kaolin and 70 parts by weight of a chlorinated paraffin with a molecular weight of approx. 580. The Brookfield viscosity was determined in the absence of the organotitanate and after the addition of 0.3 parts by weight thereof. The results show that the Brookfield viscosity in cP at 25°C was reduced from 90,000 to 18,000 when the titanate was added.

Example 7

In this example, the viscosity reduction achieved is shown

with isopropyl-rtri(dioctylpyrophosph at) titanium in a dispersion of talc in a heavy mineral oil. The control sample contained 60% by weight of talc and 40% by weight of a heavy mineral oil (flash point approx. 105°C). In the titanium-treated mixture, 1.8 parts of the above-mentioned compound are dry-mixed at 85°C in a Waring mixer with talc (3% by weight calculated on the amount of talc).

0 ~ o The control sample had a Brookfield viscosity at 25 <- pa 26,500. In contrast, the mixture according to the invention had a viscosity of only 11,000. Talc is another example of a filler with a high water content.

Example 8

In this example, the effect of the organotitanate on the impact resistance of polyvinyl chloride is shown. The relative impact strength according to Gardner for a mixture containing 100% rigid PVC is compared to that of a filled mixture containing 40% of a finely ground calcium carbonate (particle size 1-2 pm). Samples of the filled mixtures were also mixed together with varying amounts of the titanate salts, as shown in Table H. All samples in this table consist of the filled mixture with the exception of the first, which consists of 100% stiff

PVC.

The results summarized in the above table clearly show that the impact resistance of filled PVC is always improved by the addition of the titanates. The most striking improvement is achieved by the addition of the pyrophosphate compound, which gives the material an impact strength that exceeds the impact strength of the pure resin (100% PVC).

Claims (1)

Organotitanate or mixtures thereof which can be used as coupling agents between inorganic substances and polymers, characterized in that the compounds individually correspond to the formula; where R is a lower alkyl, lower haloalkyl or halogen substituted benzyl group, A is OCOZ where Z is a vinyl, methyl vinyl or ammo phenyl group; OSO 2 R 2 where R 2 is a phenyl, aminophenyl, alkylphenyl or vinylcarbonylalkyl group; -OP(0)(OR 3 ) 2 where R 3 is a long-chain aliphatic group; -OP(0)(OH)OP(O)(OR<4>)2 wherein R<4> is a long chain aliphatic alkyl group; or OAr is Ar is a cumylphenyl group; x + z is 4; x and z individually can be 1, 2 or 3; provided that, when A is -OS02R 2 > -0P(0)(OR 3>2 or -OCOZ z must be 1.