PROCEDURE FOR SYNTHESIS OF A WHITE OR LIGHT-COLOURED CROSS-LINKED HALOGEN CONTAINING POLYMER

METHODE DE SYNTHESE D'UN POLYMERE RETICULE BLANC OU DE COULEUR PALE RENFERMANT UN HALOGENE

English Abstract

2116861 9305112 PCTABS00020
White or light-coloured cross-linked polymer and a procedure for
synthesis of the same. The polymer consists of 30-98 weight
percent halogen containing polymer, 0-60 weight percent plasticizer,
0.05-10 weight percent hydrolysable mercaptosilane, 0.1-10 weight
percent lead stabilizer, 0-4 weight percent lubricant and 0.1-10
weight percent epoxy resin. The cross-linking is carried out in
the presence of moisture after the processing of the polymer.

Claims

15
Patent claims
1. White or light-coloured cross-linked polymer com-
position, comprising 30-98 weight % halogen containing
polymer, 0-60 weight % plasticizer, 0.1-10 weight %
lead stabilizer, 0-4 weight % lubricant and 0.05-10
weight % hydrolysable mercaptosilane of the general
formula,
<IMG>
where:
R' = a -CH2- -C2H4- up to C8H16 or other
non-functional group.
R'' = a freely selected (non-hydrolysable) group.
Y = one or more hydrolysable groups such as -OCH3,
-OC2H5, - OC3H7, -OC4H9
n = 0, 1, 2
c h a r a c t e r i z e d i n t h a t it contains
0.1-10 weight % epoxy resin.
2. White or light-coloured cross-linked polymer com-
position according to claim 1,
c h a r a c t e r i z e d i n t h a t the halogen
containing polymer contains a low-molecular epoxy
resin which is mono- to tetrafunctional, of the
glycidyl ether, glycidyl ester, glycidyl amine or
linear or cycloaliphatic type.
3. White or light-coloured cross-linked polymer com-
position according to claim 1,
c h a r a c t e r i z e d i n t h a t the halogen
containing polymer is PVC homopolymer.

16
4. White or light-coloured cross-linked polymer com-
position according to claim 1,
c h a r a c t e r i z e d i n t h a t the halogen
containing polymer is a copolymer between a halogen
containing monomer and a glycidyl-containing acrylate.
5. White or light-coloured cross-linked polymer com-
position according to claim 4,
c h a r a c t e r i z e d i n t h a t
the content of glycidyl-containing acrylate is 0.05-
10 weight %.
6. Process for production of white or light-coloured
cross-linked halogen containing polymer using a
mercaptosilane of the type:
<IMG>
where:
R' = a -CH2- -C2H4- up to C8H16 or other
non-functional group.
R'' = a freely selected (non-hydrolysable) group.
Y = one or more hydrolysable groups such as -OCH3,
-OC2H5, - OC3H7, -OC4H9
n = 0,1,2
as cross-linking agent and a lead stabilizer, and
where the cross-linking is carried out in the presence
of moisture after the processing of the polymer,
c h a r a c t e r i z e d b y
the fact that 0.1-10 weight % of a low-molecular epoxy
resin is added to the mixture.

17
7. Process according to claim 6,
c h a r a c t e r i z e d b y
the use of a low-molecular epoxy resin which is mono-
to tetrafunctional, of the glycidyl ether, glycidyl
ester, glycidyl amine or linear or cycloaliphatic
type.
8. Process according to claim 6,
c h a r a c t e r i z e d b y
the use of vinyl chloride as the halogen containing
polymer.
9. Process according to claim 6,
c h a r a c t e r i z e d b y the use of a co-
polymer of vinyl chloride and glycidyl methacrylate.

Description

WO93/05112 PCT/N092/00131
i
Procedure for synthesis of a white or light-colo~red cross-
linked haloqen containinq PolYmer _
The present invention concerns white or light-coloured thermo-
stable cross-linked halogen containing polymers and a procedure
for producing them.
There are several methods of cross-linking halogen containing
polymers, including PVC. Among interesting methods that have
appeared in recent years we can mention methods where
organosilanes are used as cr~ss-linkers. The patent application
DE 3719151 describes the use of organosilanes, especially
mercaptosilanes (e.g. mercaptopropyl trimethoxysilane (I)) as
cross-linking agents for halogen containing polymers,
especially the homopolymer PVC.
,:.
The cross-linking is done as follows: ;
First trimethoxysilane (I) is grafted on to the polymer chain,
and this should preferably be done hy a normal process s~ch as
compounding, extrusion or rolling.
CH2-CHCl- CH~-CHCl-
HC-Cl + HS~(CH2)3-Si-(OCH3)3 - HC-S-(CH2)3-Si-(oc~3)3 ~ HCl `
CH2-CHCl- CH2-CHCl-
~I) (II)
(- = polymer chain)
The cross-linking reaction is then carried ou~ in two steps:
By hot water or steam trea~ment alkoxysilanes are hydrolysed

W O 93/05112 ~ PC~r/N 092/00131
and form silanols. Once the silanols have been formed they
quickly react with one another and form the cross link through
condensation of H20:
CH2-CHCl-
~II) + 3H20 ~ HC-S-(CH2)3-Si-(OH)3 + 3 CH30H
CH2-CHCl-
(III)
CH2-CHCl- CH~_CHCl-
2 tIII) ~ Hc-s-(cH2)3-si(oH)2-o-si(oH)2-(cH~)3-s-cH + H20
CH2_CHCl- CH2_CHCl~
( - = polymer chain)
In Norwegian Patent Application NoO 890543 (Patent NoO 166189
halogen containing polymers are used which consist of
copolymers of halogen ontainins monomer and glycidyl
acrylates. The preferred copolymers are copolymers between
vinyl chloride monomer (VCM) and glycidyl methacrylate (GMA`.
The Norwegian patent application first and foremost differs
from DE 3719151 in that the epoxy group introduced ~y the
glycidyl monomers facilitate~.; the graftirlg of the organosilanes
to the polymer chain. The dominant grafting reaction is assumed
to take place as follows, where a copolymer of VCM and C. 05-10%
of glycidyl methacrylate are used together with (I):
O O
) " / \
C~3-C-C-O-CH2-CH-CH2 + lI)
)
~ OH
~ " /
~ CH3-c-c-o-cH2-cH-cH2-s-(cH2)3-si-(ocH)3 ()=polymer chain)
)

W093/05112 ~ PCT/~092/00131
In both the above-mentioned patent applications the cross-link-
ing takes place after processing by exposing the material to
hot water or steam. In N0 890543 it is stated that the use of
glycidyl copolymers is considerably more effective than the use
of the homopolymer PVC, inasmuch as the grafting of the organo-
silane to the polymer is more effective.
Both the cited patent applications emphasize the importance of
using lead-based stabilizers so the cross-linking will be
effective. An undesirable effect of the combination of lead
stabilizer and mercaptosilane is that the material turns yel-
low. This happens at room temperature as soon as the mercapto-
silane and lead stabilizer come into contact with each other.
It is therefore likely that the yellow colour comes from the
fonmation of a compound or complex between the lead stabilizer
and the mercaptosilane. Nor can the possibility be excluded
that the formation of this compound/complex is a preco~dition
of effective grafting. The yellow colour has a tendency to
become stronger with increased addition of mercaptosilaneO
Th~ colouring limits the usefulness of this crosc-linking tech-
nique, since even after the addition of large quantities of the
white pigment titanium oxide there is still a yellowish tone.
This means that the cross-linking method cannot be used when
whiteness is an important requirement. The colour is moreover
unstable, showing a tendency ~o change under the influence of
sunlight, for example. It is also difficult to add other col~
ours, especially light colours.
The object of the invention is thus to avoid the disadvantages
of the methods described above and to obtain a cross-linked
halogen containing polymer with a white or light oolour. In
certain systems, especially with homopolymers, a further
objective is to strengthen the network.
These and other objects of the invention are achieved by the
procedure described below, and the invention is characterized
and defined ~y the accompanying paten~ claim.

,~ 6l
1 he present invention concerns a white or light-coloured thermoslable cross-linked halogen
containing polymer composi~ion and ~ process tor producing the same. Surprisingly, it was tound
that this polymer can be produced using mercaptosilane, lead stabilizer and a low-molecular epoxy
compound. The low-molecular epoxy compound reacts with the mercaptosilane and/or the by-
products which to~ether with ~he lead stabilizer cause the colouring, and thus remedies ~he
problem.
The polymer composition comprises 30-98 weight % halogen containing polymer, 0-60 weight ~O
plasticizer, 0.1-10 weight % lead stabilizer, 0-4 weight % lubricant, 0.1-10 weight % epoxy resin
and 0.05-10 weight % hydrolvsable mercaptosilane of the general formula
.. , SH-R'-Si-R''n
where:
R' = a -CH?- -C~H4- up tO CgH16 or another oon-functional group.
R'' ~ a ~reely selected, non-hydrolysable group
..
Y -- one or rnore hydrolysable groups such as -OCH3, -OC~Hs, -OC3H7, - OC4Hg
n - 0,1,2
The group R" can be a freely selected non-hydrolysable group. Exarnples of usable groups are -
CH2- up to CgH17, but the choice of groups in principle has no significance for the result.
The low-molecular epoxy compound may consist of e.g. monofunctional or multifunclional glycidyl
ethers, glycidyt esters. glycidyl amines, or of a linear or cycloaliphatic type. This is added at 0.1-
10 weight %. An addition of less than 0.1% has no effect and an addition over 10% produces too
great a surplus of ~poxy resin in proportion to the mercaptosilane. In addition the mixture may
contain small quantities of the ordinary additives used for this type of product.
The halogen containing polymer may be a homopolymer like PVC, or a copolymer based on
halogen containing polymer and inactive or reactive comonomers with respect to the cross-linking.
A copolymer be~ween a halogen containing monomer and a glycidyl-containing acrylate is
9U~Sl lT~ E S~~T

.'li~361 :
favoured. The content of glycidyl-containing acrylate is 0.05-10 weight %. Under 0 05 wei~,ht %
the e~fect is too wealc and over lO% ?~he polymerization is too slow.
The invenliort also concerns a process for production of white or light-coloured cross-linked
halogen comaining polymer. A mercaptosilane of the above described type is used as cross-linking
agent, a lead stabilizer is supplied and where 0.1-10 weight % of a low-molecular epoxy resin is
added tO ~he mixture.. The cross-linkin~ is carried OUt in the presence of moisture ai~er the
processing of the polymer. `
It is preferred to use a low-molecular epoxy resin which is mono- to tetrafunctional, of the ~Iycidyl
ether, olycidyl ester, glycidyl amine or linear or cycloaliphatic type. ; -
It is preterably used vinyl chloride or a copolymer of vinyl chloride and glycidyl methacryla~e as
the halogen containing polymer.
The lead slabilizer is a freely selected commercial stabilizer based on e.g. tribasic lead sulphate,
tetrabasic lead sulphate, dibasic lead phosphite, dibasic lead carbonate, dibasic lead phthalate or
dibasic le~d stearate. To obtain an effect, more than 0.1% should be added. lhe upper limit is
fixe~ according to whatever is practical, there is no level that ca~not be exceeded. The
disadvanta es of high additions are more expense and higher density. A practical limit is 10 weight
%.
C)rdinary commercial plastici~ers in quantities up to 60 weight ~ are used. Above this limi~ the
mLxture caMot be handled. Commerci~l lubricants are used in quanti~ies up to 4 weight %. Higher
additions produce a mi.xmre which is overlubricated and thus difficult to handle.
The invention will be clarified in more detail in the followinjg examples. In the examples the
quantities are expFessed in pph (pph = parts per 100 parts of polymer).
SU~ S~~ T

W O 93/05112 ~ 1 1 U ~ ~ 1 PC~r/N 092/00131
;
EXAMPLE l:
Three different formulas were produced as in Table l.
Table 1
. . _ _ . _
Formula Al A2 A3
_ _ ~ _ _ _ _
PVC Homopolymer 100 100 100
DOP 53 53 53 ::
Chalk . 5 5 5
Interstab LF 36551 5 5 5
Tetra~asic lead sulphate 3 3 3
Oxidized polyethene wax2 0.5 0.5 0.5
Mercaptopropyl
trimethoxysilane (I) 3 . 3 3
Ar-ldit GY2503 0 1 _
1 = commercial lead stabilizer and lubricant combination
2 ~ external lubricant
3 = commercial epoxy resin of diglycidyl ether-bisphenol A -`:
.type, known as DGEBA resin.
DOP = dioctyl phthalate
The fo~mulas were mixed/hot-mixed up to 110 C. They were then
rolled at 170 C for 5 mins. The cross-linking was then carried
out in an autoclave at 110 C for two hours. The foll~wing ana-
lyses were carried out:
Gel content: Measured as the insoluble proportion of poly- -
mer in tetrahydrofuran (THF) at room tempera- -
ture.
Hot-set: Measured as the deformation caused by a load
of 0.1 MPa on a sample rod at 200 C after 15
mins., and as the residual deformation 5 mins.
after the load has been removed from the
sample.
Colour : Measurea visually.

WO93/05112 ,~1 1 JO ~i PCT/NO92/00131
7 :~
The results of the analyses are shown in Table 2:
Table 2:
. . _ . ..
Formula Al A2 A3 :
_ . _ ...
Gel content: 0 % 0 % O
Hot-set:
Deformation after 15 mins.: break break ~reak ~
Residual.deformation: _ _ _ :.
Colour: dark light whi~e ~::
yellow yellow
. ___ _ ~:
The results in this example show that addition of 2 pph of
DGEBA resin to a formula with 3~ trimethoxysilane (I) can eli-
minate all yellow colour. In the example no cross-linking has
arisen for. any formula. One probable reason for thiC is that
the processi~g conditions wer2 too mild for the gra~ting of
mercaptosilane to the PVC chain to work.
EXA~PLE 2:
Three different formulas were produced as in Table 3. ::
Table 3
I ~ .. __ _ __
Formula Bl B2 B3
_ ~ _ _ ___. _ ~ . . _
PVC Homopolymer l00 l00 l00
DOP 35 35 35
Chalk 5 5 5
Interstab ~F 36~5 5 5 5
Tetrabasic lead sulphate 3 3 3
Oxidized polyethene wax 0.5 0.5 0.5
Mercaptopropyl
trimethoxysilane (I) 3 3 3
Araldit GY250 0 l 2
~ _

WO93/05112 ~ 6 ~ PCT~NO92/00131
The formulas were mixed/hot-mixed up to 110 C and rolled at
190C for 5 mins. The same analyses were conducted as in
Example 1, with the results shown in Table 4:
Table 4
~ _ _ _ ..
Formula Bl B2 B3
_ _ . .
Gel content: 23 % 27 % 15 % :
Hot-set:
Deformation after 15 mins.: break break break
Residual deformation: _ _
Colour: dark light white
yellow yellow
. _. _
Here the higher procescing temperature probably contributed to
the achievement of grafting to the polymer chains and thus a
certain amount of cross-linking. Addition of a small quantity
of DGEBA resin appears to favour the cross-linking. The expla-
nation of this could be that epoxy resin, for example, which
has~reacted with two mercaptosilanes can form a bridg~:
o CH3
2 SH-(CH2)3-si-(ocH3)3 t CH2 -CH-CH2-O-Ph C-Ph-O-CH~-CH-CH2
CH3
OH CH3 OH
,/
(OCH3)3-Si-(CH2)3-5-C~-CH-CH2-O-Ph-C-Ph-O-CH2-CH-CH2-S-
C~3
(C~2)3-si-(OcH3)3 (IV~
Since in view of the low gel content there must be space
between the grafted mercaptosilanes, after hydrolysis and
condensation reactions with two mercaptopropyl trimethoxysi-
lanes (I) grafted to the polymer chain, (IV) can form a bridge
between these.

WO93/05112 ~ ~ PCT~NO92/0013t
At higher contents of epoxy resin the amount of (I) grafted to
the polymer chains is prob~bly reduced because it has mostly
reacted with the epoxy resin instead.
EXAMPLE 3:
Three different formulas were produced as in Table 5.
Table 5
_ _ _
Formula Cl C2 C3
, . _
Copolymer (VCM ~ 1% GMA) 100 100 100
DOP 53 53 53 ~:
Chalk 5 5 5
Interstab LF 3655 5 5 5
Tetrabasic lead sulphate 3 3 3
Oxidized.polyethene wax 0.5 0.5 0.5
Mercaptopropyl
trimethoxysilane 3 3 3
Araldit GY~50 0 1 2
. _ _ _ _ _ _ _
The~formulas were mixed~hot-mixed up to 110 C. They were then
rolled at 170 C for two hours. The cross-linking was later
carried out in an autoclave at 110C for two hours~ The same
analysis as in Example 1 was done. The results appear in Table
6:
Table 6
, ~. _ _ _
Formula C1 C2 C3
_
Gel content:92 % 90 ~ 84 %
Hot-set deformation after 15 118 % 156 ~ 205 %
mins.:
Residual deformation: 34 % 50 % 90 %
Colour: yellow light white
yellow .

WO93/05112 ~ PCT/NO92/00131
Example 3 shows that it is possible to produce white material
which is strongly cross-linked by adding a low-molecular epoxy
compound to the already familiar reaction between mercaptosi-
lane, epoxy-containing halogen containing comonomer and lead
stabilizer. The fact that the gel content decreases through
addition of epoxy resin and that the deformation by heat also
becomes greater is very probably a function of the fact that
the low-molecular epoxy compound "steals" mercaptosilane from
the epoxy groups bonded in the chain. We cannot exclude the
possibility that hydrolysed and condensed compounds of type
(IV) have a positive effect on the hot-set, but it is no less
effective than if (I) were grafted to the polymer chains.
. ~.
Exam~le 4
Three different formulas were produced as in Table 7.
Table 7
. _
Formula Dl D2 D3
. ~ _ _ ,,
C~polymer (~CM + 2.5% GMA) lOO 100 lOO
DOP 53 53 53
Chalk 5 5 5 `
Interstab LF 3655 5 5 5
Tetrabasic lead sulphate 3 3 3
Oxidized polyethene wax 0.5 0~5 0.5
Mercaptopropyl
trimethoxysilane 3 3 3
Araldit GY250 O 1 2
~ . . _ _
Theiformulas were mixed/hot-mixed up to 110 C~ They were then
rolled at 170 C for 5 mins. The cross-linking was later done
in an autoclave at 110 C for two hours. The same analyses as
in Example 1 were carried out. The results appear in Table 8:

WO93/05112 w i 1 ~ ~ 61 PCT/NO92/00131
11
Table 8
.
Formula Dl D2 D3
_ _
Gel content: 96 % 92 % 90 %
Hot-set deformation after lS
mins.: 37 % 55 % 67 %
Residual deformation: 7 % 14 % 20 %
Colour: ~ yel1Ow vbi~e hite
Example 4 shows that an increase of the amount of epoxy in the
polymer chains can produce a white material with lower low-
molecular epoxy resin content. The example shows the same ten-
dency as Example 3, inasmuch as addition of epoxy resin decrea-
ses the gel content and increases the hot-set deforma~ion. One .
can note that the formulas D2 and Cl in Example 3 haYe the same
gel content, but D2 is considerably better in terms of hot-set.
The explana~ion of this is probably that a higher proportion of
(I). is bonded in the polymer chains.
Example 5
Three different formul~s were produced as in Table 9.
Table 9
~ _ .
Formula El E2 E3
__ _
Copolymer ~VCM + 2.5% GMA) l00 l00 l00
DOP 53 53 53
Chalk 5 5 5
Interstab LF 3655 5 5 5
Tetrabasic lead sulphate 3 3 3
Oxidi~ed polyethene wax 0.5 0.5 0.5
Mercaptopropyl ~
trimethoxysilane 3 3 3
Araldit CYl84l 0 l 2
_. . _
l commercial cycloaliphatic epoxy resin.

WO93/05112 ~ i PCT/NO9t/00131
12
The formulas were mixed/hot-mixed up to 110 c. They were then
rolled at 170 C for two hours. The same analyses as in Example
1 were carried out. The results appear in Table 10:
Table 10
Formula E1 E2 j E3
_ _ _ . _ _
Gel content: 96 % 93 % 9~ %
Hot-set defonmation after 15 .~:
mins.: 37 ~ 44 % 58 % :
Residual deformation: 7 % 12 % 17 % ::
Colour: light white white :
yellow
_ _ _ ~ _
Cycloaliphatic epoxy resins are considered less reactive with
mercaptan groups than for example diglycidyl ether-based epoxy
resins like those of the DGEBA type. ~he higher gel content and
the lower deformation than when DGEBA resin is used may be due
to the fact that the cycloaliphatic epoxy resin does not com-
pete as well with the polymer-based epoxy groups for fI).
In Examples 3-5 the addition of low-molecular epoxy resin has
produced a lighter or white material at the expense of a rather
poorer cross-linking. The epoxy resin in all these experiments
has been difunctional~ and the n.ercaptosilane has been tetr~-
functional. This has clearly not been sufficient to ~ake an
overall positive contribution to the mechanical durability of
the network in terms of hot-set values.

WO93/0~112 ,~ PCT/NO9V~131
13
Example 6: ~
Three different formulas were produced as in Table 11. :
Table_ll
_ _ . ~ ~ ~
.Formula F1 F2 F3
. _ _
Copolymer (VCM + 1% GMA) 100 100 100
DOP 53 53 53
Chalk 5 5 5
Interstab LF 3655 5 5 5
Tetrabasic lead sulphate 3 3 3
Oxidized polyethene wax 0.5 0.5 0.5
Mercaptopropyl
trimethoxysilane 3 3 3
Araldit DY01631 0 1 _
_ . _ _ _ _.
1 Commercial tetrafunctional epoxy resin of glycidyl ether
type.
The~formulas were mixed/hot-mixed up to 100 C. They were then
rolled at 170C for 5 mins. The cross-linking was later done in
an autoclave at 110C for two hours. The same analyses as in
Example 1 were carrieid out. The results appear in Table 12:
Table 12
_ _ _ _ . _ _
Formula F1 F2 F3
_ . . . . _ , , _ ~
Gel content: 92 % 8~ ~ 79 %
Hot-set de~ormation after 15
mins.: 118 % 110 % 1~0 %
Residual deformation: 34 ~ 38 % 56 %
Colour: yellow light light
yellow yellow
_ _ _

WO93/05112 PC~/NO92/00131
1 ~6~
Example 6 shows that the use of a tetrafunctional resln makes
a contribution to the mechanical durability of the network, at
least with additions of small quantities. The fact that the
material turns light yellow is presumably due to the fact that
Araldit 01~3 itself is an intense yellow colour. The lower gel
content than in Example 3 can be explained by the fact that the
epoxy content is higher per weight unit in the tetrafunctional
resin than in the DGEBA resin.
.
In all examples where white material has been produced~ it has
only happened after autoclaving. Before autoclaving the mate-
rial had a light yellow tone. On the other hand, material with
no low-molecular epoxy content exhibits a tendency to develop
a stronger yellow colour after autoclaving. ~`
With the present invention we have arrived at a method of pro-
ducing white or light-coloured cross-linked material using hal-
ogen containing polymers, mercaptosilanes, lead stabi~izers and
a low-molecular epoxy resin. In certain formulas, especially
when tetrafunctional epoxy resin is used, a positive
con~ribution to the mechanical properties of the network can be
achieved. -