WO1992012956A1

WO1992012956A1 - Novel compounds and blends containing them

Info

Publication number: WO1992012956A1
Application number: PCT/GB1992/000052
Authority: WO
Inventors: John Groves Dolden; Philip Lance Urlwin Smith
Original assignee: The British Petroleum Company Plc
Priority date: 1991-01-15
Filing date: 1992-01-10
Publication date: 1992-08-06
Also published as: GB9100787D0

Abstract

Novel compounds of formula RO-Ph-Ph-OCO-(CH2)n-COO-Ph-Ph-OR where R is methyl or ethyl, Ph is phenylene, and n is an integer in the range 4 to 16 are useful as additives to polymers, e.g. polyethylene to improve processing.

Description

NOVEL COMPOUNDS AND BLENDS CONTAINING THEM The present invention relates to a novel class of compounds from which compounds having liquid crystal properties may be selected.

Compounds which have liquid crystal properties are known to be valuable for various purposes. Some liquid crystals are used in 5 optical displays. Other materials having liquid crystal properties have value as additives to polymer blends to improve various properties, particularly to improve properties which facilitate the processing of the polymer. The use of liquid crystal materials for mis purpose is disclosed in for example US 4 434 262 and EP 0030 471 s US 4 434 262 discloses the melt processing of polyolefins or polyesters to which certain specified liquid crystal materials have been added. These materials include two nitrogen-containing derivatives, p-methoxycinnamic acid, and lithium stearate. The examples show the use of very large amounts of the liquid crystal s material, namely 10% by weight of the blend in high density polyethylene.

EP 0030417 discloses the addition of liquid crystal materials to various polymers including low density polyethylene. The use of 10% of a known liquid crystal material (based on weight of blend) to modify o low density polyethylene gave a reduction in motor current cf less than 8%. Among liquid crystal materials disclosed is one produced by reaction of a methyl substituted biphenyl diacetate with a long chain alkane dicarboxylic acid and phenylene dicarboxylic acid.

There is a need for novel classes of compounds which can be used 5 to improve the properties of polymers which do not respond well to the addition cf known additives used to improve polymer processing.

According to the present invention there is provided a compound of formula

o RO-Ph-Ph-OCO-(CH₂ )_n -COO-Ph-Ph-OR ;I)

where R is methyl or ethyl,

Ph is a phenylene group, and n is an integer in the range 4 to 16. According to another aspect of the present invention the process for the production of a compound of formula (I) comprises reacting together

RO-Ph-Ph-OH (II) and Cl-CO-(CH₂ )_π -CO-C1 (III) , where R is methyl or ethyl, and n is an integer in the range 4 to 16 and

Ph is a 1,4-phenylene group, in a molar ratio 2:1 in an anhydrous solvent.

According to a further aspect of the invention there is provided a melt-processable polymer blend comprising a major amount of a thermoplastic polymer and a minor amount of an additive to improve processing characterized in that the additive is a compound of formula

'li¬ lt is believed to be desirable for compounds used as polymer processing aids in the present invention to possess liquid crystal properties, in particular to have a nematic phase. Liquid crystal properties are most easily observed using a polarizing microscope with a heated stage.

However materials which do not disclose high degrees of order in the melt at temperatures close to the processing temperature of the polymer (e.g for polyethylene about 190°C) when observed in this way may still retain sufficient order to provide a useful enhancement of melt processing properties.

Where the compounds used have observable liquid crystal properties then it is preferred for the temperature at which the liquid crystal material can form an anisotropic melt to overlap with the temperature at which the thermoplastic polymer melts or to have an upper temperature limit which is close to the temperature at which the polymer melts.

In order to provide liquid crystal properties at a temperature which overlaps with that of a thermoplastic polymer with which the additive is to be blended it may be necessary to reduce the melting point of the additive. The melting point can be reduced by increasing the length of the spacer chain which separates the aromatic groups. i: e value of n is 4 to 16, more preferably 5 to 12. It is most preferably at least 7, e.g. 10.

Compounds of formula (II) are known compounds. They may be made for example by reacting the sodium salt of 4,4'-dihydroxy diphenyl with dimethyl sulphate in substantially equimolar quantities at temperatures close to ambient, e.g. 20°- 35°C. The synthesis of (II) is described in Anal. Chem. 57,(3) p 653, March 1985.

Another, and preferred, method for preparing (II) is by the reaction of methyl iodide with 4.4'-biphenol. This may be carried out by the addition of methyl iodide to a stirred solution of the biphenol and an alkali (e.g. KOH) in a solvent (e.g. methanol), followed by heating (e.g at the reflux temperature of methanol.

The novel compounds of the present invention may be synthesized by reaction of 4'-alkoxy, 4-hydroxy diphenyl (II) with the acid chloride of the appropriate aliphatic dicarboxylic acid (III). The length of the alkylene chain -(CH₂)_n- in formulae (III) determines the length of the alkylene chain which acts as a spacer between the diphenylene groups in compounds of formula (I) . The value of n is in the range 4 to 16 , preferably 5 to 12, preferably greater than 7, most preferably 10.

It will be apparent to the skilled person that n is an integer for any pure compound. If mixtures are formed from a mixture of compounds containing the required alkylene groups the average value for n in the mixture may not be an integer.

The diphenyl compound and the dicarboxylic acid react together in the molar ratio of 2:1. in order to obtain the desired reaction the quantities of reactants brought into contact are preferably in a molar ratio close to 2:1

The reaction may be carried out in an anhydrous solvent. An example of a suitable solvent is dimethylacetamide. It is desirable to have an acceptor for the HCl released in the course of the reaction. A suitable base soluble in the reaction mixture may be used, e.g pyridine.

The compounds cf the present invention which produce anisotrcpic melts at temperatures which overlap with the melt temperatures of thermoplastic polymers may be added to those thermoplastic polymers as processing aids. Thus such compounds are particularly useful as processing aids for High Density Polyethylene (HDPE). Thus it is preferred to use the compounds of the present invention with polyethylene having a density of greater than 0.94 g/cm² , preferably with density greater than 0.96g/αn*-. = The compounds of the present invention which produce anisotropic melts at the appropriate temperatures may also be used as processing aids for polyacrylates, e.g. acrylonitrile/methacrylate copolymers with up to 70 mole % acrylonitrile and up to 30% wV of cross-linked polybutadiene rubber dispersed in the polymer by dispersing it in the :o monomer prior to polymerization.

The compounds are used as processing aids in relatively small amounts, for example 0.1 to 10% , e.g. 2 to 10%, based on weight of polymer, preferably 2-6% by weight.

The invention will now be described with reference to the :s following examples in which examples of the invention are identified by number and comparative tests not according to the invention are identified by letter. Example 1

:- The compound 4-'methoxy, 4-hydroxy diphenyl was prepared by reacting equimolar quantities of the sodium salt of 4,4^f-dihydroxy diphenyl with dimethyl sulphate as follows.

A two litre flask was equipped with a mechanical stirrer and stoppered dropping funnel. Dimethyl sulphate (109.38g) was weighed

:5 into the dropping funnel, which was stood upon a flat bottomed flask on a balance pan. NaOH (69.17g) and water (500ml)were charged to the reactor and stirred to dissolve the NaOH . 4,4' biphenol (160.77g! was added as powder and washed through to flask with 150ml water. The mixture was stirred vigorously to dissolve the biphenol. After lo purging with nitrogen and heating just below boiling all biphenol dissolved to give a yellow solution. It was cooled to below 35°C with continuous stirring. Dimethyl sulphate was now added dropwise from the funnel over half an hour resulting in precipitation of product. In the latter stages of addition the suspension was thick enough to stop the s stirrer rotating.

The contents of the flask were stirred with a litre of 10%w/w NaOH, and the precipitate filtered off. The filter cake was extracted with 1.5 litre of boiling water and filtered hot to remove insoluble dimethoxy biphenol (33.56g recovered). The product recovered from the hot filtrate upon cooling was redissolved hot and treated 5 with 1.73 moles hydrochloric acid. After washing in a Buchner funnel with distilled water, it was recrystallized from 1 litre of alcohol.

The material recrystallized from ethanol was filtered, washed with more ethanol and dried. 122.75g were obtained of the 4'- methoxy, 4- hydroxy biphenyl. lo Dodecane-l,10-dioic acid di(4-methoxy 4'-biphenyl) ester was formed by reacting the resulting 4'-methoxy, 4-hydroxy diphenyl (20g) with sebacoyl chloride (12g) ( a molar ratio of 2:1). The reaction was carried out in pyridine which acts as an acceptor for HCL. quantities used were 20gms of the methoxy biphenol (0.1 mole) and 12gms of is sebacoyl chloride(0.05mole) in 250 ml of pyridine. The acid chloride was added dropwise to the methoxy biphenol solution . After the exotherm had subsided, the solution was heated to 70°C for two hours, then cooled and poured into 2 litres of crushed ice. The crude product was filtered, washed successively with dilute hydrochloric acid,

2o water, and small quantities of methanol before air drying the product. It was recrystallised from toluene.

The compound was characterized by DSC (differential scanning calorimetry) and its behaviour above its melting point was ooserved by optical polarizing microscopy using crossed polar lenses to identify

:5 liquid crystal phases.

It melted about 160°C into a low viscosity nematic phase which cleared to the isotropic phase at 190° C.

The resulting product was a pure compound melting at 160°C and was identified on the basis of the synthetic route used. The compound is

30 referred to below as compound 1(1).

Example 2

35 This example shows the use of the coπipound having liquid crystal properties prepared in example 1. A blend of a high density polyethylene with 5% by weight of compound 1(1), based on weight of polyethylene, was prepared in a Brabender plasticorder fitted with a 30 ml W30 roller mixing head. ("Brabender" is a trade name).

The polymer was a high density polyethylene (HDPE) sold by BP Chemicals under the trade mark "Rigidex".

It had a melt flow index of 2g/10 minutes at 190 °C measured under a force of 21.6 kg weight.

The mixing was carried out by charging 30gms of powder into chamber using a powder chute with a ram.The ram was pressed fully down under a 5kg weight load. The temperature of the chamber was recorded at 203°C and the mixing speed was 30 rpm.

As mixing proceeded the applied torque fell to an equilibrium value when mixing was complete. This value was 12.5.Mm².

Example 3

An experiment was carried out as in Example 2 but using 2.5% by weight of compound 1(1). The equilibrium torque value was 16.2 N ² .

Comparative test A

An experiment was carried out as in example 2 except that no compound 1(1) was added to the polyethylene.

Several tests were carried out and a mean value of 17.5 +-0.5 was obtained. Addition of compound 1(1) as in Examples 2 and 3 gives a considerable reduction in the applied torque, indicating that the polymer was being processed more easily.

Example 4

An experiment was carried out as in example 2 except that the high density polyethylene (HDPE) was replaced by a polyacrylonitrile/methyl acrylate copolymer containing ca. 30% polybutadiene rubber particles dispersed within it and commercially available under the trade mark "Barex" and the mixing was carried out at a temperature of 204°C.

The equilibrium torque was 15.0 Nm.

s Comparative Test B

An experiment was carried out as in example 4 except that no compound 1(1) was mixed with the polymer. The equilibrium torque was 16.75 Nm. 0

A comparison of the results for Example 4 and Test B shows that the addition of compound 1(1) gave a significant reduction in equilibrium torque, indicating a significant reduction in melt viscosity, which is desirable for easier processing.

Example 5

4.00 gms of 4'-methoxy 4-hydroxy biphenyl were reacted with 2.67g of 1,10 dodecane dioyl chloride to form the compound dodecane-1,12- dioic acid di(4'-methoxy 4-biphenyl) ester, according to the method in the previous example. DSC (differential scanning calorimetry) peaks at 160°C and 175 °C corresponded according to observation through crossed polarizers on optical microscope to e nematic melting point and onset of clearing to isotropic at 175°C.

The yield was 4.8gms (81%). The resulting compound is identified as 1(2).

Example 6.

An experiment was carried out according to Example 2, wherein 5% of compound 1(2) prepared in Example 5 was blended with HDPE in tne Brabender at 203 °C. The equilibrium torque was recorded at 9Nm.

Example 7

An experiment was carried out according to Example 6, but using 2.5% by weight of compound 1(2). The equilibrium torque was recorded at 12.5 Nm²

Example 8

5 An experiment was carried out as in Example 6, but using 1% by weight of compound 1(2). The equilibrium torque was 16.2 Nm².

Comparative Test C

0 l,4'-butoxy 4-hydroxy biphenyl was synthesized by adding 27.4g of butyl bromide to a solution of 4,4' biphenol (37.2g-0.2mole) and 11.2g of potassium hydroxide in methanol (250mls) . The mixture was refluxed with stirring for 8 hours, cooled, and 200mls of water was added. The resulting precipitate was stirred rapidly at room temperature, cooled s to 0 °C and filtered to remove the disubstituted by-product. The filtrate was acidified to pH 3 with cone, hydrobromic acid with rapid stirring and cooled to 0°C. The crude product was filtered, washed with water, dried and recrystallised from boiling methanol. Yield was 42%, Mot was 170-2C. It was characterised by NMR and positively identified as the correct compound.

The l,4'-butoxy 4-hydroxy biphenyl was reacted with sebacoyl chloride in a mole ratio of 2:1 as follows.

2.1.2gras of sebacoyl chloride were added dropwise to a pyridine solution of 2.42gms of the butoxy phenyl phenol in 50ml pyridine. The reaction was carried out according to the procedure of example i.

The resulting compound melted at 179°C into the isotropic phase (as observed by optical microscope through crossed polars) .

The compound made as above when blended at 5% concentration with HDPE as in Example 2, resulted in an equilibrium torque of 16.3 Nm, i.e. similar to the unblended HDPE.

This experiment demonstrates the need for a nematic LC phase in order to achieve a torque reduction necessary for improved processing.

Claims

1. A compound of formula

RO-Ph-Ph-OCO-(CH )_n -COO-Ph-Ph-OR (I)

where R is methyl or ethyl,

Ph is a phenylene group, and n is an integer in the range 4 to 16.

o

2. A compound according to Claim 1 wherein n is an integer in the range 5 to 16.

3. A compound according to Claim 2 wherein n is an integer in the range 5 to 12.

4. A compound according to Claim 3 wherein n is 10.

5. A compound according to any one of the preceding claims wherein R is methyl. 0

6. A process for the production of a compound of formula (I) which comprises reacting together

RO-Ph-Ph-OH (II) and Ci-CO-(CH₂)_n -CO-C1 (III),

where R is methyl or ethyl, n is an integer in the range 4 to 16, and Ph is a 1, -phenylene group,in a molar ratio 2:1 in an anhydrous solven . 10

7. A melt-processable polymer blend comprising a major amount of a thermoplastic polymer and a minor amount of an additive to improve processing characterized in that the additive is a compound of formula (I).

8. A polymer blend according to Claim 7 wherein the thermoplastic polymer is high density polyethylene.

9. A polymer blend according to Claim 7 wherein the thermoplastic polymer is a copolymer of (meth)acrylic acid.

10. A polymer blend according to Claim 9 wherein the thermoplastic polymer is a acrylonitrile/methacrylate copolymer containing 70 mole% of units derived from acrylonitrile, and also containing up to 30% w/w of polybutadiene rubber dispersed in the polymer.

11. A polymer blend according to any one of Claims 7 to 10 wherein the quantity of additive is in the range 0.1 to 10% by weight of the polymer.

12. A polymer blend according to Claim 11 wherein the quantity of additive is in the range 2 to 10% by weight of the polymer.

13. A polymer blend according to Claim 12 wherein the quantity of additive is in the range 2 to 6% by weight of the polymer.