NL1014426C2 - Ionomeric thermoplastic rubber used in polymer composition has0.6-3 equivs./kg of functional groups at least partially neutralized to a salt - Google Patents

Abstract

Ionomeric thermoplastic rubber with functional groups at least partially neutralized to a salt, 0.6-3 equivs. functional side groups/kg and an average mol. wt. of 7000-50,000.

Description

- 1 - IONOMIC THERMOPLASTIC RUBBER 5

The invention relates to an ionomeric thermoplastic rubber, with salt-forming functional side groups, which functional side groups are at least partially neutralized to a salt group, a polymer composition and moldings of the ionomeric thermoplastic rubber.

Thermoplastic rubbers have rubber-like properties at ambient temperature. However, thermoplastic rubbers can be heat-formed as a thermoplastic polymer at elevated temperature, because a thermoplastic rubber melts or softens at elevated temperature. After softening, the thermoplastic rubber regains the rubber-like properties in a simple manner by cooling.

Thermoplastic rubbers derive this property from their chemical or physico-chemical structure. A certain class of thermoplastic rubbers is formed by the ionomeric thermoplastic rubbers with salt-forming functional side groups, which functional side groups are at least partially neutralized to a salt group. The salt groups form aggregates, which function as nodes in a rubber-elastic network at ambient temperature.

At elevated temperature, however, the cohesion of the aggregates decreases, so that the ionomeric thermoplastic rubber softens.

It is possible that the ionomeric thermoplastic rubber contains one or more additives, such as, for example, oil and other plasticizers, fillers, such as - 2 - for example, carbon black, chalk, titanium dioxide and silica, additives to further improve the processability, thermal stabilizers, UV- stabilizers and the like.

Many attempts have already been made to develop such ionomeric thermoplastic rubbers. However, it has still not been successful to obtain ionomeric thermoplastic rubbers with salt-forming side groups, which side groups have been at least partially neutralized to a salt, with satisfactory properties. US-A-3887530 discloses ionomeric thermoplastic rubbers based on a copolymer of ethylene, propylene and a diene monomer (which copolymer is now called EPDM), which as salt-forming functional side groups contain sulfonic acid groups, which are completely neutralized into a salt . The EPDM has a number average molecular weight (Mn) of between 5000-500,000 kg / kmol, a crystallinity of at least 2% and a content of salt-forming functional side groups of between 0.04 - 0.5 equivalent / kg. However, such ionomeric thermoplastic rubbers are difficult to process and the mechanical properties leave much to be desired.

The object of the invention is to provide an ionomeric thermoplastic rubber which contains salt-forming functional side groups, which functional side groups are at least partially neutralized to a salt group, which ionomeric thermoplastic rubber has good processability and good mechanical properties. Another object of the invention is to provide a polymer composition of the ionomeric thermoplastic rubber - 3 - and molded parts thereof.

Surprisingly, this object is achieved in that the ionomeric thermoplastic rubber has a number average molecular weight (hereinafter referred to as Mn) ranging between 7000 and 50,000 kg / kmol and a content of functional side groups ranging from 0.6-3.0 equivalent / kg.

It has been found that the ionomeric thermoplastic rubbers according to the invention have very good mechanical properties and are easy to process, the latter even at a high degree of neutralization. A further advantage is that the ionomeric thermoplastic rubbers already have good mechanical properties at a low degree of neutralization.

Suitable thermoplastic rubbers according to the invention are, for example, a polyolefin, polyisobutyl rubber, polyisoprene, natural rubber or styrene-butadiene rubber on which the functional side groups are grafted. Preferably, the thermoplastic rubber according to the invention is a polyolefin on which the functional side groups are grafted. The grafted polyolefin preferably has only very low crystallinity. Even more preferably, the grafted polyolefin is entirely amorphous, as can be determined by differential scanning calorimetry (DSC). Due to the very low or even completely absent crystallinity, the thermoplastic rubber has very good rubber-like properties.

Preferably, the polyolefin contains ethylene and alpha olefin monomer units. More preferably, the polyolefin contains 15-80 moles. % ethylene monomer- 4 λ <! i · »r \ λ 1 U; -r · - o -4-4 units and 85-20 mol. % C3-C23 alpha olefin monomer units. Even more preferably, the polyolefin contains 35-75 moles. % ethylene monomer units and 25-65 mol. % C3-C23 alpha olefin monomer units and most preferably 50-70 moles. % ethylene monomer units and 30-50 mol. % C3-C23 alpha olefin monomer units.

The polyolefin may contain, for example, alpha-olefin monomer units, propylene, 1-butene, 1-10 pentene, 1-hexene and / or 1-octene monomer units. Preferably, the olefin contains propylene monomer units. It is also possible, although not preferred, that the polyolefin contain, in addition to ethylene monomer units and the alpha-15 olefin monomer units, monomer units of one or more unconjugated dienes. Examples of suitable non-conjugated dienes are 1,4 hexadienes, dicyclopentadienes, 5-ethylene-2-norbornene, 1,5-heptadienes and 1,6-octadienes. The polyolefin thereby contains, for example, 0.1-10 mol% monomer units of the non-conjugated diene, while for the remainder of the polyolefin, the ethylene and alpha-olefin monomer units are present in the same proportions as defined above.

The polyolefin can be polymerized using the polymerization techniques known to those skilled in the art. The polymerization can, for example, be carried out using a Ziegler-Natta catalyst or a metallocene catalyst in solution, slurry or gas phase. Preferably, the polyolefin is polymerized in solution.

- 5 -

The ionomeric thermoplastic rubber has a number average molecular weight between 7000-50000 kg / kmolf measured using "Size Exclusion Chromatography - Differential Viscometry" combination 5 (SEC-DV) according to the universal calibration principle as described in: "Modern Size-Exclusion Chromatography by WWYau, JJ Kirkland, and D.D. Bly, John Wiley & Sons, N.Y. (1979) ".

Preferably, the ionomeric thermoplastic rubber 10 has an Mn of between 9000 - 40,000 kg / kmol, even more preferably between 10,000 - 25,000 kg / kmol.

The salt-forming functional groups according to the invention are, for example, acid groups, acid anhydride groups or side groups which are converted into an acid residue under the influence of a strong base after cleaving off a part of the side group and then form a salt group with the base. Examples of side groups which form a salt group under the influence of a strong base after cleavage of a part of the side group are ester groups which saponify under the influence of a strong base and then form a salt, amide groups which cleave off NH3 and then form a salt and maleimide groups, which cleave off an amine group and then form a salt.

Preferably, the functional groups are acid groups or acid anhydride groups. Examples of such groups are acrylic acid groups, sulfonazide substituted carboxylic acid groups, phosphonic acid groups and side groups created by grafting maleic anhydride, also referred to as succinic anhydride side groups.

More preferably, the functional groups are succinic anhydride groups. A major advantage of succinic anhydride groups is that it is quite possible to neutralize the groups only partly, because the non-neutralized groups, unlike, for example, sulfonic acid groups, do not affect the processing equipment. By only partial neutralization, an ionomeric thermoplastic rubber is created that is easy to process and yet has very good mechanical properties.

The functional groups can be present in the thermoplastic rubber because the functional groups are grafted thereon. It is also possible for the functional groups to be provided by adding a monomer with the functional group to the reaction mixture during the polymerization and polymerizing this monomer with the other monomers.

Very good results are obtained if a polyolefin is used as the thermoplastic rubber according to the invention, preferably a copolymer of ethylene and propylene, which contains as succinating functional groups succinic anhydride groups which are at least partially neutralized.

The succinic anhydride groups can be applied to the polyolefin by grafting maleic anhydride using the methods known to those skilled in the art. For example, it is possible for the maleic anhydride to be grafted using a thermal process, also known as the "one" process, or using a process that uses a radical initiator. However, the grafting can also take place very well while the polyolefin is in solution. As a radical initiator, preferably a peroxide, 10

[\ J

7 - using a hydroperoxide or azo compound. Examples include azobis isobutyronitrile, tert-butyl peroxybenzoate and dicumyl peroxide. Preferably tert-butyl peroxibenzoate is used.

Suitable solvents are, for example, xylene and hexene. Grafting of maleic anhydride onto a polyolefin is described, for example, in US-A-4010223.

The functional groups content in the ionomeric thermoplastic rubber according to the invention is 0.6-3.0 equivalents / kg. For maleic anhydride, 1 equivalent / kg equals 49 grams of maleic anhydride groups per kg of polymer.

Preferably, the content of functional groups is 0.7-2.5 equivalents / kg, even more preferably 1.2-1.8 equivalents / kg.

For example, the functional groups of the ionomeric thermoplastic rubber of the invention can be at least partially neutralized to a salt of an alkali metal such as, for example, sodium, potassium, an alkaline earth metal, such as, for example, barium, and further lanthanum, zinc, divalent tin, divalent lead, nickel or copper. Preferably, the functional groups are neutralized to a zinc salt, because the Zn ion is the least water sensitive and moreover leads to good processing and mechanical properties.

The neutralization can take place in the melt or in solution. The neutralization in solution can for instance take place by dissolving the polymer containing the not yet neutralized side groups in a suitable solvent and then in the presence of a small amount of water using a salt - 8 - of a metal ion and an acid residue to a salt group. For example, a polyolefin with succinic anhydride side groups can be dissolved in a mixture of toluene, isopropanol. Then, for example, a solution of a salt in a small amount of water is added to the solution, preferably a basic salt of a metal ion and an acid residue of a volatile acid, after which the salt group and the volatile acid are formed. The volatile acid can then be easily removed from the solution, for example by heating the solution. Preferably, a formate, an acetate, a carbonate, a bicarbonate or a nitrate are added as salt. In addition to a basic salt or salt of a volatile acid, a base can also be used, for example an alcoholate such as, for example, acetylacetonate of calcium.

Neutralization can also be performed in the melt, as described in US-A-3,264; 272 and US-A-3,404,134.

Preferably, the neutralization in solution is carried out.

Good results are obtained if the degree of neutralization is between 10 - 100%. The degree of neutralization is equal to (the number of 25 neutralized functional side groups / total number of functional side groups) x 100%. The degree of neutralization is preferably 30-80%, even more preferably 40-60%. An ionomeric thermoplastic rubber is hereby obtained which is easy to process and which, despite the relatively low degree of neutralization, already has very good mechanical properties.

The invention also relates to a polymer composition containing the ionomeric thermoplastic rubber according to the invention and one or more additives, such as, for example, oils and other plasticizers, fillers, such as, for example, carbon black, chalk, titanium dioxide, silica, additives to further improve processability, thermal stabilizers and UV stabilizers. It is also possible that the polymer composition according to the invention contains compounds which function as plasticizers for the agglomerates of the neutralized side groups of the ionomeric thermoplastic rubber. Examples of such compounds are stearamide, dimethyl sulfoxide, sodium stearate and zinc stearate. The compounds that act as plasticizers of the agglomerates are preferably added if the ionomer contains a high Mn or a high content of the functional side groups.

The polymer composition can be prepared using the techniques known for compounding rubbers, for example by adding the ionomeric thermoplastic rubber according to the invention together with the other ingredients to a batch kneader or a continuous kneader and thereby adding the mixture thus obtained. mixing and kneading at an elevated temperature, for example at 150-250 ° C, until a homogeneous composition is obtained. The composition can then be granulated and cooled.

The granulate thus obtained can be added to an extruder or injection molding machine, remelted therein and processed into molded parts.

Examples of such molded parts are hoses and profiles.

The invention is further elucidated by means of the following examples without being limited thereto.

* The content of functional groups (λ) is calculated from the grafting rate in equivalents per 5 weight unit polymer (eq / kg) according to formula I: DG * 10 * n λ = ------------- ( eq / kg) (I)

M

10 DG = grafting degree in wt% n = functionality of the side group M = molar mass of the side group (grams) 15 * The degree of neutralization is calculated according to formula II: V * ml * 100 DN = ----------- - (%) (II) Μ * λ * m2 20 V = valence of the cation (-) ml = weight of the neutralizing salt or base (gram) M = molar mass of the salt or base (gram) 25 m2 = weight of the grafted polymer to be neutralized (grams) λ = content of functional groups (kg-1) * The neutralization as used, in the examples 30 and comparative experiments, is carried out as follows: 15 grams of a copolymer of ethylene and propylene, which had been inoculated with maleic anhydride, is dissolved in a mixture of 135 grams of toluene and 15 ~.

c - 11 g of isopropanol at 80 ° C in a round bottom flask attached to a rotary evaporator. Then, 10 grams of an aqueous solution containing zinc acetate, in an amount required to achieve the desired degree of neutralization (see Form II), is added. The two-phase mixture thus obtained is stirred for 15 minutes, after which about 75 grams of the solvents are distilled off. 75 g of solvent (toluene / isopropanol) are again added to the viscous system 10 obtained. The mixture is then rotated at 80 ° C for 30 min. The solvent is then completely distilled off and the neutralized ionomeric thermoplastic rubber thus obtained is dried under vacuum at 100 ° C for 16 hours. Infrared analysis shows that the added metal salt has reacted with the functional side groups of the copolymer.

20

The properties in the following examples were measured by the following methods: * The number average molecular weight Mn was measured by SEC-DV "Size Exclusion Chromatography and Differential Viscosimetry". The equipment and experimental conditions for this SEC-DV were as follows:

Equipment: 30 - Waters M150C "Gel Permeation Chromatograph" (GPC)

Chromatography.

1 0 1 44 2 6 * ^ - 12 - - Internal heated differential refractive index DRI detector (Waters) - External differential viscometer DV detector (Viscotek) connected via a heated transfer line 5 - 0.300 ml injection volume

Columns: 4 TSK GMHxL-HT mixed bed columns Solvent: 1,2,4-trichlorobenzene stabilized with DBPC

Software: Viscotek TriSEC version 2.7 10 Calibration: Universal calibration with linear polyethylene (PE) standard molecular weight 0.4-4000 kg / mol - Mark-Houwink PE a: 0.725

Log K: -3.391 15 Sample preparation: - Concentration 0.01-0.15 mg / ml - Dissolve for 4 hours at 150 ° C under nitrogen - Then filter through a regenerated cellulose filter at 150 ° C.

20

This method is further described in detail in "Modern Size-Exclusion Liquid Chromatography by W.W. Yau, J.J. Kirkland, and D.D. Bly, John Wiley & Sons, N.Y. (1979)".

25 * The hardness (Shore A) is measured according to ASTM D2240-1991

* The compression set is measured according to ASTM D 395 method B.

* * The tensile strength, elongation at break and E-modulus are measured according to ASTM D 412, but due to the small amount of material available, specially manufactured test bars have been used.

.a S- - 13 - * Workability was determined by extruding a sample at 200 ° C through a 10 mm long, 1 mm diameter capillary with a shear rate of 1m / s-1. The surface of the extrudate was visually assessed. A smooth surface indicates that the workability is good, a rough surface that the workability is not good.

Example I

A copolymer of ethylene and propylene grafted with maleic anhydride (ethylene monomer content 45 wt.%, Mn 11000 kg / kmol, functional side groups content 1.4 eq / kg) was neutralized to different degrees of neutralization as described above. Mechanical properties were measured on the ionomeric thermoplastic rubbers thus obtained. The results are shown in Table 1.

te o o

RH

O Γ "ΓΟ O CN VD H ^

i — I LO rH Γ0 rH rH

1 <N

_ O r- ^ - m co 1-1 in o h ld '

i ΙΠ CN Μ H rH

co ΓΟ m - CN ^

O C "CO Γ0 'O

LD '1 CN -et 1 H rH

CO

^ CO

- CO CO

CO LO Γ- LD 'CO

cn ^ m co i-t cn

CN

co CO rH Lf)

"CN" CO

cc n <σ \ I — i cn o

CN CO O

Oh ^ rH

o \ ° - <~ ~ - o \ ° fO o \ ° - <u -u> Qj · - U (U s o o m - x • H X 3 4J cn g <u ω 03--0 4-) 3-1

CQ -Η X XI

η Ό m in rH rH -H CQ CD · η

(C d) (U 40 -H

rH U Si Jh 0) Λ

O 4J Ό Dl o U

Λ 3 H E o o Φ Λί c0 a> 03 O in o} h <L) H g K U cn Γ "H CÜ

LD

- 15 -

A strong increase in mechanical properties (especially compression set) results in a neutralization degree of about 50%. In addition, the mechanical properties gradually improve.

EXAMPLES II-IV AND COMPARATIVE EXAMPLES A AND B Copolymers of ethylene and propylene grafted with maleic anhydride of different Mn have been neutralized to a degree of neutralization of about 50% as described above. The neutralization was carried out with zinc acetate. The mechanical properties of the ionomers thus obtained have been measured. The results are shown in Table 2.1 h - 4 2 oaf

Ln in o vo cn m vo s} <cn cm in h vo - o in cn o in - ~ in ο ο [> ov - vo - - - I CQ vo ro o vo in v cn in co co ο h cn

VO

1-1 ld co η Γ 'h o oo vo in o ro 1 n <c ~~ - cn co o in ft CN - ~ VO O CO cn ft -vo --- <; in ro o n <in ro vo cn ro η h cn t ^ · vo ro cn vo n1 ro on ro cn co - in vo ft cn> [^ - cnctivo r ~ co -vo--

Meo ^ OLn ^ Ln ro γ- h cn ο h Ν 'cn o in CO iH cn co in oo co

M ft 00 - CN O 00 i— (tH

η oo - ~ o cn ro h co -h --- MCNoooN'N'in co ro in ο h cn r ~ N4 oo in hr ~> h in o cn m coc ^ · - ro in vo ft cn HO »- CN CN 'ΦΓ' - CN ---

H CN ΓΟ O N <in N1 00 CN ΓΟ Ο O CN

o \ ° - <- - - oV ° to o \ o —- <u -i-j a ^ 5-1 D 2 οι ο ω λ; • Η Λ 03 - p cn a <u ω rH atO '-' O -PM - - 0 - CD CD -H ^ X) - 10 (0 £ -— cn (u -η o or m to a ft CN \ o \ ° x H IH -H CQ <U TO ft S 2! JI -Ü NI> | (i Q) (D -P-rHS'- '- I — I Λ! 3 CO P Μ XI M cn Λ - (D ωΡ-ΡΤ ^ Λπη- ^ oo

Λ - (USMSooCUXiOOO

f0 CO DrOO vn o M (L) in h ro

IH 2P ^ oV = S:! X: OcNi> EHftMHW

- 17 -

Table 2 shows that from Mn> 50000 a flattening is seen in mechanical properties, in particular hardness. In addition, the ionomeric thermoplastic rubber at higher Mn, from 52 kg / mol, appears to be hardly processable, if at all.

Example VI

Copolymers of ethylene and propylene with an Mn of 11 kg / mol were seeded with maleic anhydride (1.02 eq / kg) and neutralized with monovalent, divalent and trivalent metal ions. Mechanical properties and processability of the ionomers thus obtained have been measured. The results are shown in Table 3.

S CM CN 00

+ rj CT \ CN CO ID U

CN ci »in o uj cn co

S3 ft! "Φ rH .Η» 10 - - r-H

INI U lil co CO CN CN Ο iHO

S <J \ 00 ND

+ rj ld ro cd σ \ ro m cn ro in i

cö W vd o a \ »cn - - I

J U ro ^ cn iHooi O CN CO 0 ~ + η o in co co Ό CN m '10 CO CO ID (0

(0 ffi O 00 00 10 -CO - - I-I

0Q U m CO CO LD t — 1 CN o o O

8 Η O

+ q σ \ in cn uo o3 CN rn 'CO CO U0 (0

αΐΚΓ'ΓΟ i — I CN - ft - - rH

έΟ'φΓΟ CO CO i — 1 CN o o Ü 03 (0 I—!

1 CD

I, co O "h q o cn ft a) n in CN O 03 I + 3 -, - ^ co in o s3

CO Γ- ID CO CN - O - - -H

OCJmN1 rH'sFt — ICNOi— 03 co I ^ 0 01> 0 1 — I c rj Γ0 C "in CN 5-1 + +, - Γ- · ^ ft <u

<0 ft! , Η CN COCO - H - - <U

ft U in "+ CN ^ HCNOOtSl 03 (0 1 + J, o> <r ~ cn for rj ON CO CO CO i-l

+ +, 'Ο O ft (U

-h ft ft o t — I in - ro - - cu ft U Ν '<+ COinCNCNOONl - 4-1 o \ ° 13 - <^ (0 o \ P (0 o \ o 03

- '0) 43 ft - P

^ <v s u d) o cn - · M yy

• H 33 P X

4-1 CO C OJ CD <D

(0 0 43 i-l -— CO -Η Μ X} --- (0 34

-H 03 CO 5-1 CO ft CO

CO I — i -H CO <U TO ft S Γ-Η c co ala) 4J -h s: ^> γη o s3 s-c ft m co λ ^ u

0) -H 0 43 03 Sft Γ) r, ft O <D

33 43-H; 3M6oo <UftOOSft (0 (OdOlfOOcnoMOlinrHOj ÊH I ^ CSKacNiN & HftWIjqo in - 19 -

Example VI shows that a difference in processability is observed depending on the use of monovalent or trivalent metal ions. Table 3 shows that good mechanical properties are obtained when neutralizing MAn-g-EPM with 5 monovalent metal ions. Based on the water sensitivity of the monovalent metal ions, neutralization with divalent Zn is preferred.

Example VII

Copolymers of ethylene and propylene with an Mn of 11 kg / mol were seeded with maleic anhydride, varying the graft degree (λ). The grafted EPM was neutralized with zinc acetate. Mechanical properties of the ionomers thus obtained have been measured. The results are shown in Table 4.

η ^ cn r- »'κι cm mm CO r-i LO ΙΟ CN m mom o m cn cm - - o γ- co m o i-i m · φ cn ^ I -------

LD CN CO

dl cf - 'CN CO CTi l> CO r-1 CO N1 CN N1

LHO O

mm

CN CN CN LD

co iH in n <m Ln

o o CN

N * rH "

CN LO Γ- LD

in h in m m co rH co m cn co o

> <CO (TiO

N * O LO CN N <rH

. o \ ° - << ^ o \ °

CD-1-J

Sh O) cu o cn -H, ΰ

.u cn C

m - o

^ -. 01 -H

- cn -π xs cq o \ °, ίι i — i -η cn O \ (C ® 0)

rH 5 Ö1) H yd iH

oj '^ (U-y'p & ou Λ ’3) H £ o o <ö O CL) cti O in o

^ Qr ^^ KUCNO

1 CM 4 4 4 8 ·· ^ - 21 -

It was determined that at a graft degree <0.6 eq / kg no mechanical properties can be measured anymore, a sticky and viscous material is obtained.

-ri

Claims (11)

1. Ionomeric thermoplastic rubber containing 5 salt-forming functional side groups, which functional side groups are at least partially neutralized into a salt, characterized in that the ionomeric thermoplastic rubber has a number average molecular weight between 7,000 - 50,000 kg / kmol and has a functional side group content of between 0.6-3.0 equivalents / kg. 2. Ionomeric thermoplastic rubber according to claim 1, characterized in that the ionomeric thermoplastic rubber is a polyolefin on which the functional side groups are grafted. Ionomeric thermoplastic rubber according to claim 2, characterized in that the polyolefin contains ethylene and alpha-olefin monomer units. Ionomeric thermoplastic rubber according to any one of claims 1-3, characterized in that the ionomeric thermoplastic rubber has a number average molecular weight of between 9000-40,000 kg / kmol. Ionomeric thermoplastic rubber according to any one of claims 1 to 4, characterized in that the ionomeric thermoplastic rubber contains acid groups or acid anhydride groups as functional groups. 6. An ionic thermoplastic rubber according to claim 5, characterized in that the ionomer thermoplastic rubber contains functional groups obtained by seeding with maleic anhydride. 1014 4 o - 23 - Ionomeric thermoplastic rubber according to any one of claims 1-6, characterized in that the content of functional groups is 1.2-1.8 equivalents / kg. Ionomer thermoplastic rubber according to any one of claims 1-7, characterized in that the ionomer thermoplastic rubber is neutralized to a degree of neutralization between 30-70% Ionomeric thermoplastic rubber according to any one of claims 1-8, characterized in that the ionomeric thermoplastic rubber is at least partially neutralized to a zinc salt. Polymer composition containing an ionomeric thermoplastic rubber according to any one of claims 1-9 and one or more additives. Molded part of an ionomeric thermoplastic rubber according to any one of claims 1-9 or of a polymer composition according to claim 10. j .... -. - COOPERATION TREATY (PCD REPORT ON NEWNESS RESEARCH OF INTERNATIONAL TYPE ION IDENTIFICATION OF THE NATIONAL APPLICATION Characteristic of the applicant or of the authorized representative. __3877NL_. Dutch application no. Of International Type Granted by the International Research Authority (ISA) to the request for an International Type Investigation No SN 34687 EN I. SUBJECT CLASSIFICATION (Where different classifications apply, indicate all classification symbols) According to International Classification (IPC lnt.CI.7: C08F8 / 44 II. RESEARCHED FIELDS OF TECHNIQUE __Minimum documentation examined Classification system__ Classification symbols lnt.CI.7: C08F Documentation examined other than minimum documentation if such documents are included in the areas examined III. 1 NO RESEARCH POSSIBLE FOR CERTAIN CONCLUSIONS (comments pp supplement sheet) IV. 1 | LACK OF UNIT OF INVENTION (comments on supplement sheet / ^ 7 Form PCT / ISA / 201U) 07.1979