WO1994017129A1

WO1994017129A1 - Process for surface treatment of moulded polymers of cyclo-olefins and polymer mould obtainable therewith

Info

Publication number: WO1994017129A1
Application number: PCT/EP1994/000273
Authority: WO
Inventors: Adriaan Albert Van Der Huizen; Dirk Adriaan Borger; Ronald Petrus Clemens Van Gaalen; Frederik Hendrik Van Der Steen
Original assignee: Shell Internationale Research Maatschappij B.V.
Priority date: 1993-01-29
Filing date: 1994-01-27
Publication date: 1994-08-04
Also published as: AU5972594A

Abstract

Process for the surface treatment of moulded thermoset (co)polymers of cyclo-olefins, comprising the treatment of said polymer surface with a sulfonating agent, optionally dissolved in an inert organic solvent or mixed with an inert carrier gas and subsequent neutralization with a basic compound, optionally followed by washing with an aqueous medium; moulded thermoset poly(cyclo-olefin) (co)polymers obtainable by said process, and structural composites comprising such moulded thermoset poly(cyclo-olefin) polymers.

Description

PROCESS FOR SURFACE TREATMENT OF MOULDED POLYMERS OF CYCLO-OLEFINS AND POLYMER MOULD OBTAINABLE THEREWITH

The invention relates to a process for surface treatment of moulded thermoset polymers of cyclo-olefins and in particular norbornene derivatives such as dicyclopentadiene (DCPD) and to thermoset polymer moulds obtainable therewith. More in particular the invention relates to a process for surface treatment of moulded thermoset polymers of cyclo-olefins such as are obtainable by Reaction Injection Moulding (RIM) metathesis ring opening polymerization, using a catalyst system comprising as component (1) an organo-molybdate or -tungstate and as component (2) an organo silicon, organo tin or organo aluminium compound as activator.

Processes for RIM metathesis ring opening polymerization of cyclo-olefins and in particular of DCPD and optionally structurally related comonomers , are known from European patent specification No. 0084375, US patent specification No. 4,020,254, US patent specification No. 4,481,344, British patent application No. 2,005,280, European patent applications Nos . 0222432, 0336486, 0374997 and 0480447, and US patent specifications Nos. 5,143,992, 5,095,082 and 5,142,006. The initial physical properties and in particular the impact strength of the moulded polymers, obtained by the hereinbefore mentioned processes and catalyst systems, seemed to be able to meet the requirements of most of the present commercial applications. This was even possible for an acceptable time period by use of suitable stabilizers. However, retention of these properties on longer term is still considered to be difficult.

Therefore there is a strong need for moulded (co)polymers , in particular DCPD, optionally mixed with structurally related comonomers with said (co)polymers , showing improved physical property retention. Moreover, there is a need for said moulded (co)polymers, the surface of which can more easily and efficiently be coated.

It is an object of the present invention to provide a process for the industrial manufacture of said moulded (co)poly ers by surface treatment of the initially prepared (co)polymers .

A process has now been found whereby the physical property retention of moulded thermoset (co)polymers of cyclo-olefins , can be improved. This process for surface treatment of moulded thermoset (co)polymers of cyclo-olefins, comprises the treatment of said polymer surface with a sulfonating agent, optionally dissolved in an inert organic solvent or mixed with an inert carrier gas, and subsequent neutralization with a basic compound, optionally followed by washing with an aqueous medium.

It has been surprisingly found that said treatment gives rise to an attractively improved retention of the physical properties and more in particular the impact strength of such co(polymers) .

In principle, as sulfonating agent can be used a large variety of sulfonating agents which are known to be suitable for sulfonation of organic low molecular weight compounds or saturated polymers.

Examples of such sulfonating agents are sulfuric acid, sulphur trioxide, optionally mixed with an inert carrier gas, such as dry air, carbon dioxide, nitrogen, helium, argon, or dissolved in an inert organic solvent such as dioxane, pyridine, benzothiazole , dimethylformamide, hexamethylphosphotriamide, triethylphosphate, dichloroethane, tetrachloromethane; or acetyl sulfate, dissolved in an organic solvent as specified hereinbefore and preferably in 1 ,2-dichloroethane.

Preferably acetyl sulfate dissolved in 1,2-dichloroethane is used, in a concentration of from 0.1 to 2 M and preferably of from

0.3 to 1 M. A sulphur trioxide density which is typically obtained

2 is in the range of from 1 to 3 mg/cm .

In case of using sulphur trioxide, mixed with an inert carrier gas, practical concentrations of the sulphur trioxide will be in the range of from 5 to 20 vol% and preferably in the range of from

10 to 15 vol%.

The surface treatment of thermoset (co)polymers by sulfonation according to the present invention was found to be carried out to provide a sulfonation degree, measured by XPS analysis of the treated polymer surface, in the range of from 1 to 25% and more preferably in the range of from 1 to 10%.

The sulfonation treatment is typically carried out at temperatures in the range of from 0 to 50 °C and preferably in the range of from 15 to 30 °C and lasts for approximately 0.1 to

30 min. , preferably 10-30 min. , and more preferably from 5 to

15 min.

According to a specific embodiment of the present surface treatment of thermoset (co)polymers, the present invention using sulphur trioxide and including subsequent neutralization with e.g. ammonia gas, lime slurry or caustic can be carried out according to the process and equipments as known from e.g. the European patent applications Nos. 0356,966 and 0340,617.

Usually a sulphur trioxide solution having a concentration of from 0.001 to 10% and more preferably from 0.4 to 2% in the reagent solution is applied.

For the neutralization step can be used an aqueous solution of an inorganic base, such as sodium hydroxide, potassium hydroxide, calcium hydroxide; ammonia in the form of a gas or an aqueous solution, or organic amines such as tertiary amines (e.g. polyethylene imine, trimethylamine, pyridine, dimethyl formamide) or epoxy compounds (e.g. glycidyl acrylate or glycidyl methacrylate) , optionally dissolved in an inert organic solvent such as dichloromethane, dioxan, tetrahydrofuran or diethylether and preferably dichloromethane.

Preferably an aqueous NaOH solution, having a molar concentration of from 0.5-5 M and preferably from 1 to 3 M, or glycidylmethacrylate (GMA) solution in dichloromethane, having a molar concentration of from 0.5-5 and more preferably from 1 to 3 M is used. It will be appreciated that the starting moulded polymers of cyclo-olefins may consist of homopoly ers or copolymers of structurally related norbornene derivatives.

More preferably (co)polymers of DCPD, optionally mixed with another structurally related comonomer, such as Diels Alder adducts comprising divinyl cyclohydrocarbon compound such as 3,5-divinyl- cyclopentene and cyclopentadiene optionally mixed with dicyclopentadiene or oligomers thereof are used as starting polymers. Moreover the thermoset moulded poly(cyclo-olefin) to be modified according to the process of the present invention, may contain one or more elastomers as impact improver, such as ethylene-propylene-diene monomer elastomers (EPDM) or block copolymers derived from vinyl aromatic compound (e.g. styrene) and conjugated diene (e.g. butadiene and/or isoprene) in an amount of from 2 to 10 wt% and preferably from 3 to 5 wt%.

In addition the thermoset moulded poly(cyclo-olefin) starting polymer may contain other auxiliary materials, such as fillers, flame retardants, fibres, anti-oxidants, stabilizers, pigments and plasticizers .

According to a preferred embodiment of the present process, a moulded poly(cyclo-olefin) is surface treated, which thermoset moulded poly(cyclo-olefin) is obtainable by RIM metathesis ring opening polymerization with the help of a catalyst composition, comprising (1) a tungsten compound, derived from a tungsten halide or oxyhalide with a phenol compound, which is substituted on the phenyl ring by alkyl, alkoxy, containing 1-6 carbon atoms, aralkyl containing 7-15 carbon atoms or halogen and preferably chlorine or bromine, and (2) an organo metal compound, derived from tin, silicon, lithium, sodium, potassium, aluminium, borium, magnesium, berillium, calcium, zinc or combinations thereof.

It will be appreciated that another feature of the present invention is formed by the moulded thermoset, poly(cycloolefin) - (co)polymers obtainable by the hereinbefore described process showing an improved impact strength. In Journal of Polymer Science. Part A, Polymer Chemistry, vol. 26, 429-444 (1988) and ibidem, vol. 28, 1377-1386 (1990), J.P. Plancne et al, has been described the sulfonation of polynorbornene in dilute solution in an organic solvent such as 1,2-dichloroethane up to a degree of 55% sulfonation.

From neither of these articles a teaching could be derived by a person skilled in the art, about the effect of sulfonation of the present relatively large moulded polymers, as in both articles only small poly(norbornene) particles (powdery) were sulfonated with the aim to make these polymer particles partly or totally water soluble, whereas the aim of the present process was to form a barrier layer having low permeability for oxygen and providing an improved oxidative protection.

It was further known from US patent specification No. 4,220,739 to sulfonate organic materials such as polyethylene, polystyrene and polypropylene by contacting them with an essentially dry gaseous mixture of sulphur trioxide and chlorine, providing organic polymers which were alleged to be adhesive, antistatic and highly impermeable to oleophilic materials such as gasoline and common hydrocarbon solvents, and to low molecular weight gases such as oxygen and carbon dioxide.

However, no reference at all was made in especially columns 2 and 3, specifying possible starting materials, to thermoset moulded polymers from monomers, such as DCPD and the like. From US patent specification No. 3,911,184 it was known to prepare an enclosure member substantially impermeable to the transmission of gases comprising a solid sulfonatable aromatic polymer having a plurality of free hydrogen atoms attached to the carbon atoms thereof, said member having at least one surface which has a portion of hydrogen atoms thereof replaced by an amount of polyamine sulfonate salt groups sufficient to give improved gas barrier properties to said member.

In US patent specification No. 3,770,706 it has been described that in order to render organic polymers such as polyethylene, polystyrene and polypropylene adhesive, antistatic and highly impermeable to oleophilic materials and to low molecular weight gases such as oxygen and carbon dioxide, the surface of the organic polymer iε to be initially and subsequently the substituent sulfonic acid groups are to be reacted with an organic epoxide , including an alkylene oxide, to form the corresponding ester of sulfonic acid, such that the surface of said polymer composition contains from about 0.001 to about 50 milligrams of sulphur trioxide equivalents per square centimetre.

However, neither of these three US patent specifications give any suggestion to sulfonation of a thermoset polymer, still containing residual carbon-carbon unsaturation in order to avoid said deterioration of its physical properties and in particular the impact strength.

In addition from French patent specification No. 2,588,873 compositions of sulfonated polymers derived from polynorbornene are known. Said compositions could be obtained by different sulfonation methods applied in solution, suspension or in bulk whereas the starting polymers have average molecular weights from about 10.000 to several millions and varying sulfonation degrees. However, said disclosed polynorbornene polymers were clearly intended to be used in the field of elastomers, wherein the main properties were on the one hand a remarkable damping and on the other hand a strong capacity of oil absorption.

Moreover, it is known from said French patent specification that a moderate sulfonation of the polynorbornenes leads to ionic elastomers, being susceptible for thermoreversible ionical cross-linking, while at sulfonation degrees of 50% or more, these polymers become hydrosoluble, maintaining a very high viscosity. Said sulfonated polymers are indicated to be useful as thickening polymers and in particular for the supported recovery of hydrocarbons, flocculation agents for water treatment or in the paper industry.

It will be appreciated that no suggestion can be derived by a person skilled in the art from this publication on how to improve physical property retention of the thermoset polymers of the present invention.

It will be appreciated that another feature of the present invention is formed by one integrated process step comprising RIM polymerization in a mould of cyclo-olefins, and in particular DCPD, optionally mixed with other structurally related comonomers, using ring opening metathesis catalyst systems as specified hereinbefore, and subsequent surface treatment and neutralization immediately after the almost quantitative polymerization in the thermoset mould.

As a result of the specified embodiments of the treatment process, the thermoset (co)polymer moulds can be used for a large number of applications, for example for structural composites (a) in the automotive industry or building industry, and (b) in the electrical industry, e.g. in printed circuit boards, wherein the retention of initial physical properties and in particular the impact strength is an important requirement.

The invention will be further illustrated by the following examples, however, without restricting its scope to these embodiments. EXAMPLE 1 1. Poly-DCPD sulfonation method

At room temperature RIM poly-DCPD plaques, thickness 3 mm, containing 3.5% of EPDM as toughener and 1.0% of BHT (butylated hydroxytoluene) as anti-oxidant were immersed for different times

(5-30 min.) in a 0.5 M solution of acetylsulfate in dichloroethane. After removal of residual reagent by a dichloromethane wash the samples were immersed for 5 min. in aqueous 1.0 M NaOH for neutralization. Then the samples were washed with water and dried under vacuum at ambient temperature.

Gravimetric analysis of the samples showed a weight gain, corresponding with the time of sulfonation (cf. Table I). In all cases XPS analysis of the treated polymer surface also showed a considerable increase of the sulphur and oxygen level, indicating effective sulfonation. 2. Testing method

Both sulfonated and reference samples were oven aged in air at 70 °C. All samples were subjected to high rate impact testing according to ISO 6603-2.

3. Results

The results of the impact tests before and after aging are listed in Table II. The data clearly illustrate the positive effect of increasing level of sulfonation on the aging resistance of poly-DCPD. For example, at 300 h the untreated sample lost considerable impact performance, whereas the 30 min. sulfonated sample retains e.g. 95% of its original impact energy.

TABLE I

GRAVIMETRIC AND XPS DATA ON SULFONATED SAMPLES

SULF. TIME S0_ DENSITY XPS SURFACE ANALYSIS (%W) (MIN) (MG/CM²) C O S

0 0 94 4 0

5 0.7 59 27 8

10 0.8 54 29 9

30 1.2 59 26 8

TABLE I I

IMPACT DATA ON AGING OF SULFONATED SAMPLES

SULF. TIME IMPACT* VS. AGING TIME (HR, 70 °C)

(MIN) O H 80 H 300 H

RS E MF RS E MF RS E MF

(N/mm) (J) (kN) (N/mm) (J) (kN) (N/mm) (J) (kN)

0 657 79 7.9 665 75 8.3 416 29 2.6

5 715 77 8.7 743 63 7.4 427 27 2.1

10 723 62 7.8 704 54 7.4 679 48 5.1

30 757 73 8.1 761 76 8.5 699 69 7.1

* RS = Relative Stiffness, E = Total Energy, MF = Maximum Force. EXAMPLE 2

At room temperature RIM poly-DCPD plaques, thickness 3.2 mm, containing 3.5% of EPDM as toughener and 1.0% of BHT as anti-oxidant were immersed for 30 min. in a 0.75 M solution of acetyl sulfate in dichloroethane. After removal of residual reagent by a dichloromethane wash the samples were neutralized in two different ways:

(a) Immersion for 5 min. in aqueous 1.0 M NaOH and subsequent washing with water.

(b) Immersion for 5 min in a 1.0 M solution of glycidyl methacrylate (GMA) in dicloromethane and subsequent washing with water.

XPS analysis of the sulfonated polymer surface (after neutralization with NaOH) gave a relative atomic sulphur concentration of 9.5%. This is higher than in the previous examples and corresponds with data from gravimetric analysis which show an

2 SO, density of 2.7 mg/cm .

Testing

Oven aging was carried out at 70, 90 and 110 °C during 2 weeks. All samples were subjected to high rate impact testing according to ISO 6603-2.

Results

The results of impact testing before and after aging are given in Table III.

TABLE III

Neutr. Method Impact Energy (J) vs. Aging Temperature (°C)

I 70 I 90 I 110 I

I 0 2 weeks | 0 2 weeks | 0 2 weeks|

NaOH I 96 7 | 96 49 | 96 50 |

GMA I 93 73 I 93 65 | 93 47 |

Untreated | 93 < 20 | 93 < 20 | 93 < 20 |

It will be clear that the retention of the impact performance of the treated samples is much better than in the case of the untreated ones.

Claims

C L A I M S

1. Process for surface treatment of moulded thermoset (co)polymers of cyclo-olefins, comprising the treatment of said polymer surface with a sulfonating agent and subsequent neutralization with a basic compound.

2. Process according to claim 1, characterized in that the sulfonating agent is dissolved in an inert organic solvent or mixed with an inert carrier gas .

3. Process according to claim 1 or 2, characterized in that the neutralization is followed by washing with an aqueous medium.

4. Process according to claim 2 or 3, characterized in that as sulfonating agents are used either sulfuric acid, sulphur trioxide, optionally mixed with an inert carrier gas, such as dry air, carbon dioxide, nitrogen, helium, argon or dissolved in an inert organic solvent such as dioxane, pyridine, benzothiazole, dimethyl- formamide, hexamethylphosphotriamide, triethylphosphate, dichloroethane, tetrachloromethane, or acetyl sulfate, dissolved in an organic solvent as mentioned hereinbefore.

5. Process according to claim 4, characterized in that as sulfonating agent acetyl sulfate dissolved in 1,2-dichloroethane, is used.

6. Process according to claim 5, characterized in that acetyl sulfate is used in a concentration of from 0.3 to 1 M.

7. Process according to any one of claims 1-6, characterized in that a sulphur trioxide density is provided in the range of from 1

2 to 3 mg/cm .

8. Process according to any one of claims 1-4, characterized in that sulphur trioxide, mixed with an inert carrier gas, is used in concentrations in the range of from 5 to 20 vol% and preferably in the range of from 10 to 15 vol%.

9. Process according to any one of claims 1-8, characterized in that the sulfonation treatment lasts for approximately 0.1 to

30 min and preferably 10 to 30 min.

10. Process according to any one of claims 1-9, characterized in that the neutralization is carried out using ammonia gas or an aqueous solution of an inorganic base or an organic amine or an epoxy compound optionally dissolved in an inert organic solvent.

11. Process according to claim 10, characterized in that an aqueous NaOH solution, having a molar concentration of from 0.5-5 M and preferably from 1 to 3 M, is used.

12. Process according to claim 10, characterized in that glycidylmethacrylate (GMA) solution in dichloromethane, having a molar concentration of from 0.5 to 5 M and more preferably from 1 to 3 M, is used.

13. Process according to any one of claims 1-12, characterized in that DCPD, optionally mixed with other structurally related monomer(s), such as Diels-Alder adducts from divinylcyclopentene, is used as starting monomer.

14. Process according to any one of claims 1-13, characterized in that one or more elastomers are included in the thermoset moulded poly(cyclo-olefin) in an amount of from 2 to 10 wt%.

15. Process according to any one of claims 1-14, characterized in that the thermoset moulded poly(cyclo-olefin) is obtainable by RIM metathesis ring opening polymerization with the help of a catalyst composition, comprising:

(1) a tungsten compound, derived from a tungsten halide or oxyhalide with a phenol compound, which is substituted on the phenyl ring by alkyl, alkoxy, containing 1-6 carbon atoms, aralkyl containing 7-15 carbon atoms or halogen, and (2) an organo metal compound, derived from tin, silicon, lithium, sodium, potassium, aluminium, borium, magnesium, berillium, calcium, zinc or combinations thereof.

16. Process according to any one of claims 1-15, which process is carried out in one integrated process step comprising RIM polymerization in a mould of cyclo-olefins using ring opening metathesis catalyst systems and the subsequent surface treatment and the n itralization immediately after the almost quantitative polymerization in the thermoset mould.

17. Thermoset moulded cyclo-olefin polymer, obtainable by a process as claimed in any one of the preceding claims.

18. Structural composites comprising thermoset moulded cyclo-olefin polymer according to claim 17, for use in the automotive industry, building industry or in the electrical industry.