CA1332133C - Miscible polymer blends - Google Patents

Abstract

ABSTRACT

An article constituted of two different polymers which are capable of forming compatible polymer blends, the first of which polymer components is A) a polymer P1 that is made up of at least 30 wt.% of monomers of Formula I:

I
in which R1 is hydrogen or methyl and R2 is a hydro-carbon group of 1-18 carbon atoms, and the second of which polymers is B) a polymer P2 that is made up of at least 30 wt.% of monomers of Formula II:

II

in which R3 is hydrogen, methyl, or a -CH2-X-CHR5R6 group, X is a -?-Z-, -Z-?-, or Z-?-Z'- group, with Z
being oxygen or -NR4, Z' being oxygen or NR4, and R4 being hydrogen or an alkyl group of 1-12 carbon atoms, wherein -CHR5R6 stands for an aliphatic or araliphatic hydrocarbon group of 5-24 carbon atoms, said article being of such a design that one of the polymers forms a coating on the other, or one of the polymers forms a coating on a compatible polymer blend PM made up of A) 0.1 - 99.9 wt.% of a polymer P1 and B) 99.1 - 0.1 wt.%
of a polymer P2.

Description

3~21 33 BACKGROUND OF THE INVENTION

Field of the Invention:
This present invention relates to articles ~;
constituted of two different polymers which form compatible polymer blends, namely alkyl-substituted ;
polystyrene as polymer component Pl and a polymer component P2 containing carbonyl groups. One of the polymers forms a coating on the other polymer, or a coating on the compatible polymer blends PM. ,;

Description of the Back~round:
Different polymeric species as a rule are norm-ally not compatible with each other when mixed, i.e., different polymeric species do not generally form~a !
homogeneous phase down to small proportions of one component that would be characterized by complete miscibility of the components. Certain exceptions from this rule have generated increasing interest, specifically among those who are concerned with the theoretical interpretation of the phenomenon. Mixtures of those polymers which are fully compatible show complete solubility (miscibility) in all ratios.

~* '~
. .~' :' : ' ~,, ' . .

- ~ - 2 - 1 332 1 33 , . ..

Reviews of miscible polymer systems, for example, are described by D.R. Paul et al in Polymer &
Engineering 18, (16) 1225 - 34 (1978); J. Macromol.
Sci.-Rev. Macromol. Chem. C. 18 (1) 109 - 168 (1980), and in Annu. Rev. Mater. Sci., 1981, 299 - 319. The glass temperature Tg or the so-called optical method which is based on the clarity of a film cast from a homogeneous solution of the polymer blend, have been used frequently to prove miscibility of polymer blends.
(Cf. Brandrup-Immergut, Polymer Handbook, 3rd Ed~, III-211-213). The occurence of the lower critical ;~
solution temperature (LCST) is used as another test for the miscibility of polymers differing from one another.
(Cf. German Patent Expositions 34 36 476.5 and 34 36 477.3, both published on April 10, 1986). The ~: . .- .
`~ occurrence of the LCST is based on the process of a -~
: .
clear, homogeneous polymer blend seperating into phases --upon heating and becoming optically turbid to opaque. -~-According to the literature, this behavior represents clear proof that the original polymer blend had consisted of a single homogeneous phase in equilibrium. ~-;
For further characterization of blends, see also the `~
paper by M. T. Shaw: "Microscopy and Other Methods of Studying Blends" in "Polymer Blends and Mixtures", ~ .
edited by D.J. Walsh, J.S. Higgins, and A. Maconnachie, NATO ASI Series, Series E: Applied Sciences - No. 89, ~ -:
pp. 37-56, -:: ;-~ .- .
~... ,.. ~ ~

1 3 3 2 1 3 3 : :

Martinus Nijhoff Publishers, Dordrecht/Boston/Lancester 1985. The systems of polyvinylidene fluoride with polymethyl methacrylate (PMMA) or with polyethyl :, .:
methacrylate are examples of miscible polymer systems -~
(U.S. Patents 3,253,060, 3,458,391, 3,459,843). More recent results on "Polymer Blends" and possible uses of them are reported by L. M. Robeson in Polym. -Engineering & Science 24 (8) 587-597 (1984).
Copolymers of styrene and maleic anhydride, as well as styrene and acrylonitrile under certain conditions are compatible with polymethyl methacrylate (PMMA) (German Patent Exposition 20 24 940, published -~
on December 2, 1970). The improved practical properties of molding compositions of these types have been emphasized. In the same way, copolymers of styrene and monomers containing hydroxyl groups capable of forming hydrogen bridges with certain compositions are compatible with polymethacrylates, for example copolymers of styrene and p-(2-hydroxyhexafluoroisopropyl)styrene [B. Y. Min and Eli - ;
.i ~ . --.. ~
M. Pearce, Organic Coating and Plastics Chemistry, 45, (1981) 58-64], or copolymers of styrene and allyl ;~
alcohol (F. Cangelosi and M. T. Shaw, Polymer Preprints (Am. Chem. Soc. Div. Polym. Chem.) 24, (1983), ~
258-259). ~ `
Polystyrene itself, as well as other polymers `~
containing styrene compounds, on the other hand, are '-_4_ 1 3321 33 considered to be incompatible with polymethyl methacrylate. Thus,a miscibility of only 3.4 ppm (PMMA
with a molecular weight of 160,000) or of 7.5 ppm (PMMA
with a molecular weight of 75,000) with polystyrene is reported by Shaw, M. T. and Somani, R. H. ~Adv. Chem.
Ser. 1984, 206 (Polym. Blends Compos. Multiphase syst.)~ 33-42 (C.A. 101: 73417e)]. Even very low molecular weight polystyrene has little compatibility with PMMA. Thus, even a mixture of 20% of an extremely low molecular weight styrene oligomer (MW : 3,100) in ;~
PMMA does not form a clear product. With a likewise very low molecular weight of 9,600, even a 5% solution in PMMA is only translucent. (Raymond R. Parent and Edward V. Tompson, Journal of Polymer Science: Polymer Physics Edition, Vol. 16, 1829 to lS47 (1978)).
Other polymethacrylates and polyacrylates are similarly very slightly miscible with polystyrene in attempts to form transparent plastics. This applies, for example, to polyethyl methacrylate, polybutyl `~
methacrylate, polyisobutyl methacrylate, polyneopentyl methacrylate, polyhexyl methacrylate, and many ~;~
others. Refe~also to R. H. Somani and M. T. Shaw, Macromolecules 14, 1549-1554 (1981). ~ ;
An exception to this generally observed ~
incompatibility between poly(meth)acrylate and ~;
polystyrene is reported in two recent patent ~

, ' "~; ~

_ 5 _ ~ 3~2 1 33 applications (P 36 32 370.5 and P 36 32 369.1, both published on March 31, 1988). As disclosed in these ;;
applications, polystyrene and poly-~-methylstyrene are extraordinarily compatible with polycyclohexyl methacrylate and polycyclohexyl acrylate. The compatibility of polycyclohexyl (meth)acrylate with ~ -~
polystyrene and poly-~-methylstyrene is so good that there is still compatibility between the polymers containing styrene and the polymers containing ;~
cyclohexyl (meth)acrylate when the cyclohexyl (meth)acrylate is present in the copolymer in an amount of less than 50 wt.~ (for example, 30 wt.~). Likewise, the styrene can be largely replaced by other comonomers without the compatibility between the polymer ~
containing styrene and the cyclohexyl (meth)acrylate ~-being lost. Besides this extraordinary complete miscibility of cyclohexyl (meth)acrylate with polystyrene and poly-~-methylstyrene, the miscibility of polystyrene is also described specifically only with polyvinyl methyl ether, polyphenylene oxide, and ~ ~`
'. ! i .
tetramethylbisphenol-A polycarbonate (D. R. Paul and J.
! i W. Barlow, J. Macromol. Sci-Rev. Macromol. Chem., C 18 (1), 109 - 168 (1980)).
Miscibility of polymer blends is generally ;~
explained as being based on specific interactions between the various polymeric species in the blend.

~ . . - ' ~ I 332 1 33 Thus, the compatible polymer blends mentioned above (for example, tetramethylbisphenol~A poly-carbonate/polystyrene) are explained by electron donor/acceptor complex formations. (Refer to J.W. -~
Barlow and D.R. Paul, Annu. Rev. Mater. Sci., 1981, 299-319).
Most of the compatible polymer blends recognized so far, however, can be attributed to specific interactions such as the hydrogen bridging which occurs, for example, with phenoxy/polyester, PVC/polyester, i SAA/polyester, PC/PHFA, and PVDF/PMMA; see J.W. Barlow and D.R. Paul, Annu. Rev. Mater. Sci. 1981, 303, 304).
While the compatible polymer blends mentioned above can be attributed to hydrogen bridging bonds or to electron donor/acceptor complexing, the compatibility of ; ;~
PMMA with specific copolymers of styrene and acrylonitrile or a-methylstyrene and acrylonitrile, each of which is found only at a specific -styrene/acrylonitrile or a-methylstyrene/acrylonitrile ratio, is explained by intramolecular repulsion within the copolymers between the two comonomers styrene and `;
acrylonitrile. Thus, it is also understandable that compatibility is found only in very special compositions of the copolymers, for example, between PMMA and SAN.
slnce compatibility is ,.. '.;':"' ', ~ ",~j",X,j";, ~7~ 1 332 1 33 found only with very specific comonomer ratios, the term "miscibility windows" is employed. (J.-L. G.
Pfennig et al., Macromolecules 1985, 18, 1937 - ~;~
1940). Such "miscibility windows" are also reported for compatible mixtures of aliphatic polyesters and polyhydroxy ethers of Bisphenol A. In this case, the aliphatic polyesters are considered to be copolymers of CHX- and COO monomeric units. (D. R. Paul and J. W.
Barlow, Polymer, 25, 487 (1984)). Paul and Barlow, in this work, have shown that exothermic miscibility can exist as the driving force for miscibility even when none of the interaction parameters are negative. Only a sufficiently large energy of repulsion between the ;
comonomers of the copolymer is necessary. ;~
- ~
Gerrit ten Brinke et al have also explained that this same concept explains the miscibility of halogen-substituted styrene copolymers with poly(2,6-dimethyl-1,4-phenylene oxide) ~Macromolecules 1983, 16, 1827-32). Ouglzawa and Inoue, Polym. J., 18, 521 - 527 (1986)~expIain the miscibility of poly(acrylonitrile/
styrene) with poly(acrylonitrile/butadiene) in the same wa;y.
Therefore, while the compatibility of specific copolymers with other polymers, as discussed above, is ~;
explained by intramolecular repulsion within the copolymers, on the one hand, and the "miscibility ' ~ ''';

-8- 1 3~21 33 windows" that are found are thus explained, specific interactions are always called upon for the interpretation of the compatibility of homopolymers such as, for example, EDA complexes in the case of polyphenylene oxide/polystyrene and hydrogen bridges in the PVDF/PMMA system. Accordingly, there is no complete unified theory by which the ~iscibility of polymers can be predicted so that new compatible polymer blends could easily be postulated. However, ~ ;~
such compatible polymer blends are being sought for many applications. In fact, mixtures of polymers (polyblends) in certain cases and in certain fields of the plastics industry have led to plastic products with improved properties (cf. Kirk-Othmer, 3rd Edition, Vol.
18, pp 443-478, .J. Wiley 1982). The physical properties of such "polyblends" ordinarily represent a compromise that, in the last analysis, can mean an ~;
improvement over the properties of the individual polymers. Multiphase polymer blends have greater commercial importance by fa than the compatible blends (cf. Kirk-Othmer loc. cit. p. 449). A need there continues to exist for compatible polymer blends which ~-~
permit the development of new and useful products.

~ .
'.' ~``':" .
:. :.
'':~' 1 332 1 33 ~

SUMMARY OF THE INVENTION

Accordingly, one object of the present invention is to provide a compatible polymer blend of two polymer components Pl and P2. .
Briefly, this object and other objects of the :-present invention which hereinafter will become more readily apparent can be attained by an article constituted of two different polymers capable of forming compatible polymer blends, the first of which polymers .~:~
i s A) a polymer Pl that is made up of at least 30 .
wt.% of monomers of Formula I~
:~ ~Rl CH2 = C I :--~ in which Rl i8 hydrogen or methyl and R2 is a -~ hydrocarbon group of 1-18 carbon atoms, and the second q,~ of which polymers is B) a~polymer P2 that is made up of at least 30 wt.% of monomers of Formula II:

:: CH2=lc II

~;7, ~

~;
', ~
: ' X , ~

-lo- 1 3~21 33 : ~ ~

in which R3 is hydrogen, methyl, or a -CH2-X-CHR5R6 ~ ~
Il 11 11 :.,:
group, X is a -C-~-, -Z-C-, or Z-C-Z'- group, with Z = ~
oxygen or -NR4, Z' = oxygen or NR4, and R4 = hydrogen ~ ;
or an alkyl group of 1-12 carbon atoms, wherein -CHR5R6 stands for an aliphatic or araliphatic hydrocarbon group of 5-24 carbon atoms, said article being of such a design that one of the polymers forms a coating on ~-~
~; the other, or one of the polymers forms a coating on a -compatible polymer blend PM made up of A) 0.1 - 99.9 wt.% of a polymer Pl and B) 99.1-0.1 wt.~i of a polymer ?2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS .
-~ Multiphase and compatible polymer blends can be strictly differentiated both with regard to their physical properties and with regard to their applied -properties, particularly their optical properties which ~`
include transparency, clarity, and the like. As d1scussed above, deficient compatibility frequently ~:~
sets narrow limits on the~mixing of plastics with the purpose of achieving an improved overal property `-`
spectrum. However, the state of the art teaches nothing about discovering the compatible polymer blends required by technology.
It has been found that the concept of repulsion between the comonomer units, for example, the repulsion ~.. ;.

... ;~.' ,.

."''~

~ 1 332 1 33 . - 1 1 - ' :

between styrene and acrylonitrile ln SAN which has been invoked to explain the compatibility of copolymers, can also be applied to homopolymers, and that rules can be derived from them for technical procedures. The teaching for the understanding of polymer blends accordingly foresees miscibility between different types of polymers Pl and P2 when:
1) Polymer Pl is made up of monomeric units with at least two subunits chemically differentiable from one another that repel one another, and 2) Polymer P2 likewise consists of monomeric units that in turn again consist of at least two - ~ .
subunits chemically differentiable from one another that likewise repel one another, and 3) A negative or only slightly positive enthalpy of mixing is measured for the mixing of the hydrogenated monomeric units of Polymer 1 with Polymer 2.
The theory effortlessly explains the miscibility between polymers containing halogen, on the one hand, ;and~po1ymers containing carbonyl groups, on the , 1 other.~ As can be proven with other examples, mixtures ! ' ' ~ ~ . , , ' of alkanes and perfluoroalkanes are generally endothermic. Thus, the two subunits, i.e., the CH2 and CF2 groups which repel each other, are combined in PVDF
in one monomeric unit. In the same way, PMMA is made -.~ ,, -12- 1 3~21 33 : ~

:-- ::
up of two mutually repelling subunits which are a ::~
hydrocarbon group and an ester group.
The types of polymers which are compatible in the present invention are two different polymer species whose compatibility cannot be explained either by ~:;
hydrogen bridge bonds or by EDA complexing. An ~-important aspect of the present invention is the ~.
finding that polymer blends PM of two different polymers Pl and P2 have good compatibility when~
a~ Polymer Pl is made up of monomers of Formula I
or contains these monomers as the major constituent:

',~ Rl ,:
CH2 = C I

R2 ,,., :.
~: ~
, ~

wherein Rl stands for hydrogen or methyl and R2 stands ,~;
for a hydrocarbon group with 1-18, preferably 1-12 : carbon atoms; and .";~
b) Polymer P2 is made up of monomers of Formula ::
II olr contains them~as the major constituent: ~ , R3 ~ .
CH2=C i.,;.,.:.;'`' ;"~ :' ~: C~R5R6 ::~

wherein R3 stands for hydrogen, methyl or a -CH2-X-CHRsR6 group, O O O
Il ~1 .
X stands for a -C-X-, -Z-C-, or -Z-C-Z'- group, wherein Z is oxygen or NR4, Z' is oxygen or NR4, and R4 is hydrogen or an alkyl group with 1-12, preferably 1-5 carbon atoms. :
In the group R3 above, -CHRsR6 stands for an aliphatic or araliphatic hydrocarbon group with 5-24 carbon atoms, either with Rs and R6 being connected to form an optionally substituted ring with 5-12 carbon atoms in the ring, or with Rs standing for hydrogen or an aliphatic hydrocarbon group with 1-5 carbon atoms and R6 standing for an optionally branched aliphatic, araliphatic, or aromatic hydrocarbon group with 4-18 carbon atoms. R2 also preferably stands for an aliphatic hydrocarbon group. The optionally substituted groups may have inert substituents such as, for example, ~
n-alkyl, iso-alkyl, and t-alkyl groups with 1-6 carbon : :
atoms, for example, methyl, ethyl, propyl, isopropyl,:
butyl, and the like. (Also see below the description of .
~;~ the R2 group as -CH3CR7Rg, cf. page 16).
. Polymer blends PM of polymer Pl and polymer P2:
are of particular interest when they satisfy the additional condition that the Van der Waals volumes Vw :~
of the :~
. . ~ - :

~ ~ ~, i 1 , , ' ' , ~ '''~ . ' :: ,.
' :~
X

-~ ~,.
R2 group satisfy the expression:

(1) Vw . 1,8 > Vw -X-CHRsR6 - ~ R2 -X-CHRsR6 In this expression, Vw stands for the Van der Waals volume expressed in cm~/mole of the -XCHR5R6 group and Vw Q stands for the ~,~
- ~ R2 corresponding Van der Waals volume of the _ ~ R2~

group. For the definition of the Van der Waals volume, see A. Bondi, J. Phys. Chem. 68, 441 (1964); M. Charton n Topics in Current Chemistry, VoI. 114, Steric Effect5 in~Drug Design, p. 107, Springer Verla~ 1983.
Especlally;~preferred are polymer blends PM that satisfy the~condition~

;(2~ Vw~ . 1,5 ~ VW > 0,7 . Vw ; -X-CNRsR6 ~ ~ R2 -X-CHRsR6 Also preferred are polymer blends PM that satisfy the condition that the hydrogenated (saturated) monomer ~;
units of the polymer Pl~

,~ ' ':

Rl ' Hl CH3 - ~C - H

~ R2 ': ~

~ and the hydrogenated monomer units of the polymer P2: `
~, . . .

have at the most a small positive enthalpy of mixing, e-~ QHmixing Hl/H2 < 50 cal/mole of mixture, or preferably have a negative enthalpy of mixing, so that~
mixing Hl/H2 ~ cal/mole of mixture Aa~a rule,~;thi exothermlc mixing of the hydrogenated monomer~unlts and thus also the miscibility of the ~-polymers ~Pl and~P2 ls~produced by repulsion within the monomer~ u~nits~of the~polymer Pl and within the monomer ~un~lts of~the~polymer~P2, as discussed supra with the examples ~of~ PVDF/PMMAi and~;PVC/PMMA.
The repulsion between monomer units of the polymer P2~orlglnates from the repulsion discussed above ' between~the~ polar~X gro~up and the aliphatic -CH2-CR3 group and;the~-CHR5R6 group. On the other hand, the ~-repuls~ion within the monomer unit of the polymer Pl origi~nates fr~om the repulsl~on~between aliphatic and -.~, ~ ' !

' ' '"'.i''";'';

-16~ 2l 3 3 aromatic hydrocarbons. It is a very general rule that compatibility of polymer P1 and polymer P2 exists especially when the forces of repulsion between the `
monomer units are particularly large. Good miscibility between the polymers Pl and P2 is therefore found especially when the aliphatic portion in the main chain -- ;
that is directly adjacent to the phenylene group in the monomer unit of the polymer Pl and directly adjacent to -~
the polar group X in the monomer unit is as distinct as possible. Thus, as a rule, better compatibility with the polymers P2 is found with polymers with Rl = CH3 ~-~
than with polymers in which Rl = hydrogen. This is `~
particularly true for a small R2 group, i.e., R2 =
Cl - C4. Quite similarly, particularly good compatibility with the polymers Pl is frequently found in the group of polymers P2 when R3 = CH3. It is also advantageous for the -CHR5R6 group to constitute a continuous, compact hydrocarbon, provided, as a rule, that the X-CHR5R6 group is matched in its space requ1rement to the - ~ R2 group, i.e., the groups have comparable Van der Waals volumes.
While a number of -CHR5R6 substituents are practical with large R2 substituents, for example : ~:
R2 > 4 carbon atoms, as long as the CHR5R6 group has only at least 5 carbon atoms, CHR5R6 groups of the cycloaliphatic type or phenylalkyl groups are preferred -:;
, ~ 332 1 33 - 17 - ;
especially with a small R2 group such as, for example, methyl. The R2 group can be located in principle in the 0, m, or p-position on the phenyl group. However, the m- or p-position and very particularly the p-position, is preferred.
As mentioned, the R3 group represents either hydrogen, methyl, or a group of the -CH2-X-CHRsR6 type.
R3 groups with R3 being hydrogen or methyl are preferred. Among the -CH2-X-CHRsR6 groups, those with the structure -CH2-C-Z- are preferred.

O O

The group X is of the type -C-Z-, -Z-C-, or O O O
-Z-C-Z, with groups of the type -C-Z- and -Z-C- being preferred, and with the group -C-Z- being particularly preferred.
In principle, -Z- can be oxygen or a -NR4- group with R4 being hydrogen or an alkyl group, especially with 1 to 5 carbon atoms. Oxygen or a -NR4- group with R4 being hydrogen are very generally preferred.
However, -Z- groups in which -Z- is oxygen are most particularly preferred.
As already mentioned, it is desirable for the ;
-CHs-R6 group to be matched in its space requirement ~Van der Waals volume) to the - ~ 2 group- -CHRsR6 ,'~
: ::
;, ' -18- l 332 1 33 groups in which R5 and R6 are closed to form a ~
cycloaliphatic ring are of special interest. Rings ; ;
with 5-12 carbon atoms in the ring can be considered here. Preferred are rings with 5-7 carbon atoms, and esp~cially preferred are cyclohexyl groups. The cycloaliphatic ring can also be substituted in each case. The mutual adaptation mentioned above applies here also. ~ha~ is, if Rl is hydrogen and R2 contains no quaternary carbon atoms, i.e., a carbon atom bonded ~-to 4 other carbon atoms, the cycloalkyl group should not be disubstituted on one ring carbon atom, i.e., in ~
this case the CHR5R6 group should also have no ~;-quaternary carbon. Conversely, especially when the R2 group contains a quaternary carbon, the CHR~R6 group can also contain a quaternary carbon. In this case, ;~
CHR5R6 groups in which at least one carbon of the ,.. ~ ~ . .
7':~ CHR5R6 group, i.e., generally one carbon atom of the R~
group, is substituted with one hydrogen atom at the most are even preferred. As a rule, R5 will be hydrogen or wiIl form a ring with R6. Furthermore, however, RS can also represent an alkyl group with 1-5 ca~rbon atoms.
~ ~
~ Considering the monomers of Formula I which .~ , .
essentially make up the polymer Pl, in general all alkyl-substituted styrenes and/or ~-methylstyrene are practical, and R2 groups in which R2 represents a :: :
: ' ~ ,`' . ~
~: .
i ~

CH3CR7R8 group can be mentioned in particular, with R7 representing hydrogen or an alkyl group with 1-8 carbon atoms and R8 representing an alkyl group with 1-8 -carbon atoms~ Especially preferred are R2 groups in which R7 and R8 are methyl. In addition, R2 can also be methyl, ethyl, or n-propyl.
The content of monomers of Formula I in polymers Pl is governed by the extent of compatibility required -and amounts to at least 30 wt.~, as a rule at least 60 wt.~, and preferably at least 80 wt.~. Such polymers Pl with at least 95 wt.~ content of monomers of Formula I are especially preferred. When Rl = H, homopolymers Pl of the monomers of Formula I are the most preferred embodiment.
:, .
~ If comonomers are present at all in the polymers, ~; ~ .,.. ~, .;, vinyl monomers different from those of formula I are ~ ;

especially practical as comonomers for the preparation ~-.: ., of polymer Pl. (Cf. Ullmann's Encyclopedia of Industrial Chemistry, 3rd Edition, Volume 14, pp. 108 10~, Urban ~ Schwarzenberg 1963). Monomers that are ;;~
formed from only the elements of carbon, hydrogen, and oxygen are preferred. In particular, these are vinyl ~;
esters and/or (meth)acrylic acid esters, generally ; ~
those with 4-22 carbon atoms in the molecule. The -polymer can also contain styrene or ~:
:'`,.'','' ' 1 3~21 33 ~-methylstyrene in minor amounts, i.e., in fractions of less than 20 wt.
While the polymer Pl can be modified by the presence of other hydrophobic vinyl compounds, the fraction of very polar monomers such as acrylamide, -~
acrylonitrile, maleic anhydride, maleimides, p-~2-hydroxyhexafluoroisopropyl)styrene, and allyl alcohol is very limited. The fraction of these polar monomers i;-should be below 10 wt.~, or below 5 wt.~ of the polymer Pl. Preferred are polymers A that contain less than ~
0.1 wt.% of these polar monomers, and especially those -that do not contain polar monomers. The content of the monomers II in polymers P2 is likewise governed by the extent of compatibility required and is at least 30 wt.~, generally at least 50 wt.~, preferably 70 wt.%, and in an especially preferred embodiment > 95 wt.%.
For many applications, the use of homopolymers formed from monomers II is of very particular interest for constructing the polymers P2.
In addition to the monomers of Formula II, the monomers mentioned for the polymer Pl are useful as aomonomers for constructing the polymèr P2, with the use of very polar monomers being limited here also. As ;
a rule, polar monomers are limited to a content of < 20 ;
wt.~, preferably ~ 5 wt.~, if they are not completely excluded.
~: ~.;'"

-21- 1 3~2 1 33 The monomers o~ Formula II that essentially constitute polymer P in an amount greater than 50 wt.%, if not actually 100%, are the vinyl esters, vinylamides, vinyl carbonates, vinylurethanes, and vinylureas that can be derived from Formula II, as well as the corresponding propenyl compounds. ~
The monomers of Formula II also include amides and ~;
esters of itaconic acid. Preferred monomers II, however, are esters and amides of acrylic acid and methacrylic acid. As mentioned previously, the esters -~
are very generally preferred here. When monomers of Formula II containing nitrogen are used, those without NH groups are preferred. Monomers of Formula II that can be mentioned especially are optionally substituted vinyl or propenyl esters of cycloalkanecarboxylic acids ;
and cycloalkyl carbonates, cycloalkyl acrylates, cycloalkyl methacrylates, and cycloalkyl itaconates, optionally substituted vinyl esters or propenyl esters -~
:
of phenylalkylcarboxylic acids and phenylalkyl ` ~ carbonates, phenylalkyl acrylates, methacrylates, and - itaconates. Especially worthy of mention are cycllohexyl acrylate and cyclohexyl methacrylate.
However, it must always be noted that the monomers of ~ ~ormula II of the polymer ~1 and the monomers of ;~ Formula II of the polymer P2 cannot be viewed in ;~
isolation. Thus, the repulsion of the subunits of the monomer unit I and the van der Waals volume of the subunits of monomer unit I must always be viewed in relation to repulsion of the subunits of the monomer unit II and their van der Waals volume. Thus, for example, poly-p-t-butylstyrene, as polymer Pl, has a pronounced, sterically demanding aliphatic portion (the t-butyl group) directly next to the phenylene group.
The pronounced repulsion thus present between the aliphatic and aromatic portions of this monomer unit ;
makes poly-p-t-butylstyrene an ideal mixing partner for polymer P2, with the sole limitation that polymer P2 -should likewise have pronounced repulsion between the ~
monomer units, i.e., a large aliphatic group -CHR5R6 ~! 1;,' ' besides the polar group X, or, preferred, a branched aliphatic -CHR5R6 group. Consequently, poly-p-t-butylstyrene (polymer Pl) also has unlimited compatibility with the sterically hindered poly-3,3,5-trimethylcyclohexyl acrylate over the blending range mentioned of 1:99 to 99:1. Complete compatibility is found with this polymer blend PM over the entire experimentally accessible temperature range of up to >
2500C.
An example of a polymer blend PM of the invention with unlimited compatibility is:

.';:

-23- 1332133 ~ ~

Polymer P1 Polymer P2 with the units [~ lC = O
CH3 - - CH3 ~

CH3 ~ CH3 In contrast to poly-p-t-butylstyrene as polymer ~ --P1, poly-p-methylstyrene has no distinct aliphatic -~
areas next to the phenylene group, i.e., the repulsion of the group within the monomer unit is substantially ~
smaller. Thus, the breadth of variation within the l`j -polymer P2 is also smaller. Consequently, poly-p-methylstyrene is completely incompatible with the poly- ;~
3,3,5-trimethylcyclohexyl acrylate mentioned above. On the other hand, complete compatibility is found with ~ ;
the~polycyclohexyl acry~late as polymer P2. Neither poly-p-methyl-styrene nor polycyclohexyl acrylate has ~ ~-quate~rnary ca~rbon atoms in the alkyl group and they are `~
;thus~cQmparable in~geometry. On the other hand, poly-p-t~-butylstyrene, wh~ich has excellent compatibility ~`
with~sterically hindered polymers P2, already shows distlin~ctly reduced compatibility as polymer Pl with the"~;~ir~
s~ter1cally~lesa hindered polycyclohexylacrylate as polymer~P2, which has a distinctly smaller van der ~-Waals volume. These polymers are actually still ;
completely compatible at room temperature, but separation occurs at approx. 80C.

i An example, of a polymer blend pursuant to the ~ -invention which exhibits unlimited compatibility is:
Polymer Pl Polymer P with the units:

- CH2 - CH _ - CH2 - ~
~=0 '~

CH3 ~ , Besides these polymer blends which are compatible over `~
the entire temperature range and in all blend ratios, polymer blends PM which are compatible only within a limited temperature range such as, for example, < ;~
100C, are also of lnterest. As a rule~ the blending ratio of polymer Pl to polymer P2 can ~e varied within ,.
broad limits. Thus, the polymer blends PM pursuant to the invention generally consist of:
, A) 0.1-99.9, preferably 5 to 95 wt.~ of a polymer ~; Pl which is made up of at least 30 wt.~ of the monomers ;
of Formula I, and B) 99.1-0.1, preferably 95 to 5 wt.% of a polymer P2 which is made up of at least 30 wt.% of the monomers of ~ormula II.
; The fact of whether polymer Pl can also contain monomers of Formula II or whether polymer P2 can also contain monomers of Formula I depends on the requirements of area in which the polymer blend is used. As a rule, the content of the monomers of Formula I in the polymer Pl should be greater by at least 30 wt.% than the content of the monomers of Formula I in the polymer P2. Similarly, the content of monomers of Formula II in the polymer P2 should be at least 30 wt.% greater than the content of monomers of ~-Formula II in the polymer Pl. Polymer blends in which ~;~
the content of monomers of Formula I in the polymer P2 is less than 10 wt.%, especially 0 wt.~, and the ;~
content of monomers of Formula II in the polymer Pl is likewise less than 10 wt.~, especially 0 wt.%, are especially preferred. In general, the content of monomers of Formula I in the polymer P1 and the content -~
of monomers of Formula II in the polymer P2 can be small especially when the other monomer units in the polymer Pl and in the polymer P2 are largely the same chemically.
The polymer blends PM are characterized as compatible mixtures by the recognized criteria as ~i descr1bed Ln Kirk-Othmer, loc. ci~., Vol. 18, pp. 457 460.
a) When using optical procedures, a single refractive index is observed with the polymer blends PM
pursuant to the invention that lies between those of the two polymeric components Pl and P2.
b) The polymer blends PM have a single glass transition temperature Tg which lies between those of the polymeric components.

,,~"",,, :. ,, ,.,- .

For the further characterization of the polymer blends PM pursuant to the invention, see also the paper by M. T. Shaw in "Polymer Blends and Mixtures"
mentioned above.
The compatibility criteria mentioned above are also important for the application of the polymers P2 pursuant of the invention as coating materials for polymers Pl. This invention, as mentioned, includes within its scope objects prepared from compatible polymer blends PM with a coating consisting of polymer -P2.
~:
Preparation of the Polymers Pl and P2 Polymers P1 and P2 can be made following the known rules of polymerization and by known procedures. For example, the polymers of type Pl can be made by the procedure of Houben-Weyl, Methoden der Organischen -Chemie, 4th Edition, Vol. X V/l, pp. 761-841, Georg Thieme-Verlag (1961). Some of polymers P1 are available in suitable form on the market. The radical polymerization procedure can preferably be used to ;~
prepare the polymers, but ionic polymerization procedures can also be used. The molecular weights M
of the polymers Pl of the invention are generally above 3,000, preferably in the range of 5,000 - 1,000,000, and especially in the range of 20,000 - 500,000.

-27- 1 3321 33 ~
,. :' (Determination by light scattering). It should be pointed out, however, that the molecular weights do not seem to critically affect the suitability of the polymers as components in the compatible polymer blends ;;
PM. This applies both to the homopolymers and to the copolymers of both types Pl and P2. The tacticity of the polymers is of definite importance for the compatibility of polymer Pl and polymer P2. As a rule, a polymer P2 with a small fraction of isotactic triads, as obtained by radical polymerization, for example, is~ -~
preferred in particular over polymers with a high isotactic fraction, as produced by special ionic polymerization. -~
The homopolymers and copolymers P2 are generally made by radical polymerization.(Cf. H. Rauch-Puntigam, Th. Volker, Acrylic and Methacrylic Compounds, Springer-Verlag 1967). Even though preparation by i-~
anlonic polymerization or group transfer polymerization is possible in principle, for example, in the case of :. ~
acrylic acid or methacryIic acid derivatives, (see also O. W. Webster et al., J. Am. Chem. Soc., 105, 5706 (1983)), radical polymerization is nevertheless the -`
preferred form of preparation. ;
The molecular weights M of the polymers P2 are generally above 3,000, usually in the range of 10,000 to 1,000,000, preferably 20,000 to 300,000. In the selection of the monomer components that are to be used as comonomers for P2, care mu3t be taken that the glass temperature Tg of the resulting polymer does not have a limiting effect on the technical applicability of the overall system PM.
At least one of the polymers P1 and P2 should have a glass transition temperature Tg > 70C for the preparation of molded objects. It is preferred or such applications that the polymer blend PM also have a glass transition temperature Tg > 70C. This limitation applies especially to the production of injection molded, pressed, or extruded objects.
However, polymer blends PM that have a polymeric component P2 with a glass transition temperature Tg <
40C or preferably 20C are preferred for other fields of application, for example, in the manufacture of varnishes.
The compatibility of the polymer blends PM
suggests corresponding possible industrial uses for the blends, with Pl or P2 in each case being mentioned as representatives of the possibilities falling under polymers P1 or P2.
1. It is possible to make an optical gradient fiber by coating P1 with P2, for example, with the following configuration: Core: Pl, jacket P2, transition: continuous. As a rule, nD20pl > nD2p2 Such fibers can be used, for example, as optical waveguides.
2. Articles of Pl with a thin jacket of P2, especially of P2 with (copolymerized) W absorbers are also available. (Cf. R. Gachter, H. Muller, Handbook of Plastics Additives, Hanser-Verlag 1979, pp. 90 -, :.
143; British Patent 21 46 647; U.S. Patent 4,612,358). In contrast to uncoated Pl, such articles ~
are stable to weathering. The otherwise serious ~''.,,~',! '.;
problem of the reuse of heterogeneously coated plastic wastes is eliminated, since wastes can be ~
reincorporated because of the good compatibility. As a ~- `
rule, articles made of Pl or of a polymer blend PM are made by injection, compression, extrusion, rolling, or casting. The jacket of polymer P2 is usually applied -~
by varnishing or by coextrusion.
3. Panels of Pl with a coatin~ of P2 can be formed. Panels with such construction show light transmission improved by up to 2% over untreated panels made of Pl. As a rule, panels with a coating of P2 also show better scratch resistance and modified corrosion resistance. The good adhesion of the polymers P2 to the panels made of ~1 should also be emphasized. In particular, this permits making panels of Pl with a coating of P2 by coextrusion. Of special interest are multiple-web panels, such as those used ~,"
' ', -~30- ] 332 1 33 for windows in greenhouses, for example, that have been made of Pl or of a polymer blend PM and have a coating of P2.
~ urthermore, molded objects of Pl can be cemented with the polymer P2, or advantageously with monomer/initiator mixtures containing monomers II. In this case the high rate of polymerization of the ~. ~
monomers II, especially if R3 is H~can be combined with good polymer compatibility.
Having generally described this invention, a further understanding can be obtained by reference to certain specific examples which are provided herein for purposes of illustration only and are not intended to `~
be limiting unless otherwise specified.
Reduced viscosity (~spec/c) is determined by the -~;
methods of DIN 1342, DIN 51562, and DIN 7745. Light transmission can be determined by DIN 5036, if not noted otherwise. Turbidity (haze) is given in % (ASTM
D 1003?. Measurements are generally made on a plate 3 mm thick. The ratios indicated are ratios by weight.
'~`'~ .
~ .
~ExamDle 1 -~
-~A plate of poly-p-methylstyrene 3 mm thick (J = 83 i~
ml/g) is coated with a 20% solution of a polymer P2 in a solvent mixture consisting of 40 wt.% diacetone alcohol ~ ~ ' 40 wt.~ isopropanol 20 wt.~ methyl ethvl ketone . ':'.'.
and is then dried at 90C. Characterization of the `~
polymer P2: a copolymer of 49 wt.% methyl methacrylate, ~
49 wt.% cyclohexyl methacrylate, and 2 wt.% cyclohexyl , -acrylate (J = 32 ml/g) prepared by radical polymerization. -The result is a glass-clear plate having a coating which exhibits good adhesion.

~ Exam~le 2 - A coating of polycyclohexyl methacrylate (J = 31 ml/g) about 10 ~m thick is applied to a plate of poly-p-methylstyrene (J = 83 ml/g) 1 mm thick. The coated plate thus obtained is ground, granulated, and again extruded into plates 1 mm thick (simulation of waste -~
recovery). The plates thus obtained are glass-clear, like the pure poly-p-methylstyrene plates.
;~ Having now fully described the invention, it will be apparent to one of ordinary skill in the art that many changesiand modifications can be made thereto without departing from the spirit or scope of the invention as set forth herein. ;~
:~ , ' '

Claims (9)

1. An article constituted of two different polymers which are capable of forming compatible blends, the first of which polymers is A) a polymer P1 that is made up of at least 30 wt.% of monomers of Formula I:

I
in which R1 is hydrogen or methyl and R2 is a hydro-carbon group of 1-18 carbon atoms, and the second of which polymers is B) a polymer P2 that is made up of at least 30 wt.% of monomers of Formula II:

II
in which R3 is hydrogen, methyl, or a -CH2-X-CHR5R6 group, X is a -?-Z-, -Z-?-, or Z-?-Z'- group, with Z
being oxygen or -NR4, Z' being oxygen or NR4, and R4 being hydrogen or an alkyl group of 1-12 carbon atoms, wherein -CHR5R6 stands for an aliphatic or araliphatic hydrocarbon group of 5-24 carbon atoms, said article being of such a design that one of the polymers forms a coating on the other, or one of the polymers forms a coating on a compatible polymer blend PM made up of A) 0.1 - 99.9 wt.% of a polymer P1 and B) 99.1 - 0.1 wt.% of a polymer P2.

2. The article of Claim 1, wherein in polymer P1, R2 is CH3CR7R8 in which R7 is hydrogen or C1-8 alkyl and R8 is C1-8 alkyl.

3. The article of Claim 1, wherein the styrene monomers of Formula I constitute at least 30 wt.% of polymer P1.

4. The article of Claim 1, wherein said polymer P1 contains at least one comonomer selected from the group consisting of vinyl esters, (meth)acrylic acid ester and combinations thereof.

5. The article of Claim 1, wherein the monomers II of polymer P2 constitute at least 30% wt.% of the polymer.

6. The article of Claim 1, wherein the monomer of Formula II is an acrylic ester, itaconic ester, vinyl ester, vinyl amide, vinyl carbonate, vinyl urethane or vinyl urea.

7. The article of Claim 1, wherein P1 and P2 form an optical gradient fiber.

8. The article of Claim 1, wherein the polymer P2 forms a coating on the polymer P1.

9. The article of Claim 1, wherein the polymer P2 contains an optical stabilizer.