Ultraviolet curable terpolymers of trioxane, from at least 65 weight percent to about 75 weight percent of 1,3-dioxolane and from about 2 weight percent to about 20 weight percent of a monoethylenically unsaturated aliphatic diol formal having at least 4 carbon atoms in its main chain, e.g., 4,7-dehydro- 1,3-dioxepin, which are non-crystalline at room temperature or above are disclosed. These terpolymers, when admixed with a multifunctional crosslinking monomer, e.g., a multifunctional acrylate such as 1,6-hexanediol diacrylate, and a photosensitizer, e.g., a benzoin compound such as benzoin isobutyl ether, can be cured to an insoluble, non-tacky, rubbery state using UV radiation. The thus-cured polymeric materials form useful crosslinked films, and when cryogenically ground to a suitable small particle size can be blended with conventionally prepared crystalline oxymethylene homo-, co- and terpolymers to improve the latters' impact properties.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to novel acetal terpolymers. More particularly, this 
invention relates to novel ultraviolet (UV) curable terpolymers of 
trioxane, 1,3-dioxolane and certain formals of monoethylenically 
unsaturated aliphatic diols. These terpolymers are non-crystalline at room 
temperature (about 25.degree. C.) or above by virtue of having higher 
dioxolane contents than copolymers or terpolymers hitherto contemplated by 
the prior art, although they can be made to crystallize at temperatures 
below room temperature. They can be admixed with multifunctional acrylates 
or similarly - performing multifunctional crosslinking monomers and a 
photosensitizer or UV initiator and cured to an insoluble, non-tacky, 
rubbery state using UV radiation. The resulting cured polymeric materials 
form useful crosslinked films, and can also be cryogenically ground to a 
suitable small particle size and then blended with conventionally prepared 
crystalline oxymethylene homo-, co- and terpolymers to improve the impact 
properties of molded articles made therefrom. 
2. Description of the Prior Art 
Commonly-assigned copending U.S. patent application Ser. No. 07/096,187, 
filed of even date herewith in the names of George L. Collins, Paul Zema 
and William Pleban and entitled "Low Tg Non-Crystalline Acetal 
Copolymers", discloses and claims low Tg (glass transition temperature) 
trioxane/ 1,3-dioxolane copolymers which are also non-crystalline at room 
temperature or above (although they too can be made to crystallize at 
temperatures below room temperature) and which have a dioxolane content 
greater than 65 mol percent and less than about 75 mol percent and an IV 
(intrinsic viscosity) of from about 1.00 to about 2.3, as measured by 
standard viscometric measurements, e.g., in o-chlorophenol. These 
copolymers contain no unsaturated sites for subsequent crosslinking, and 
are not disclosed as being curable by reaction with multifunctional 
crosslinking monomers under UV curing conditions. 
Trioxane/1,3-dioxolane/unsaturated diol formal terpolymers are disclosed in 
U.S. Pat. No. 3,297,647, issued January 10, 1967 to Schott et al. The 
unsaturated diol formals disclosed in the Schott et al patent include 
2-butene-1,4-diol formal, 2-hexane-1,4-diol formal and 
2-(2-ethyl)butene-1,4-diol formal (column 2, lines 11-14), the amounts of 
monomers disclosed are as follows: 
"(t)he cyclic ether or saturated cyclic formal is advantageously used in an 
amount of 0.1 to 59.9% by weight, calculated on the total monomer mixture. 
The formal of the unsaturated diol is advantageously used in an amount of 
59.9 to 0.2% by weight, calculated on the total monomer mixture. The 
trioxane is advantageously used in an amount of 40 to 99.8% by weight, 
calculated on the total monomer mixture", 
column 2, lines 17-24, and the patentees had this to say about the 
interrelationships between monomer contents and polymer properties: 
"The physical properties of the terpolymers can be varied within wide 
limits and depend, on the one hand, on the nature and concentration of the 
saturated cyclic formal or saturated cyclic ether and, on the other hand, 
on the concentration of the formal of an unsaturated cyclic diol. 
For example, when 0.1 to 10% by weight, calculated on the total monomer 
mixture, of unsaturated cyclic formal and 0.1 to 10% by weight, calculated 
on the total monomer mixture, of saturated cyclic formal or ether are used 
highly crystalline products are obtained, whereas with 40 to 59.9% by 
weight, calculated on the total monomer mixture of unsaturated cyclic 
formal or ether, amorphous elastic glass-clear products are obtained. The 
more voluminous the second comonomer, the lower is the crystallinity and 
the higher is the elasticity. The decrease in crystallinity can be well 
measured by means of X-rays. 
Low molecular weight terpolymers which constitute waxes or oils can easily 
be obtained with the use of high concentrations of catalyst, that is about 
0.1 to 1% by weight, calculated on the total monomer mixture. 
The above statements are intended to indicate the wide limits within which 
the properties of the terpolymers obtained by the process of the invention 
may be varied, the incorporation of different comonomers having, of 
course, different effects on the properties of the terpolymers and the 
transitions being fluid", 
column 2, lines 25-52. 
The Schott et al patent does not disclose terpolymers having 1,3-dioxolane 
contents in excess of 59.9% by weight, based on the total weight of 
monomers present, or blends of its terpolymers with crystalline 
oxymethylene polymers. And while Schott et al do disclose that their 
olefinic unsaturation-containing terpolymers can be crosslinked: 
"(v)ery interesting properties are imparted to the terpolymers of the 
invention by the double bonds contained in the main chain, which double 
bonds enable the terpolymers to be crosslinked by known methods. For 
example, the terpolymers may be vulcanized by kneading with sulfur", 
column 2, lines 53-58, there is neither a disclosure of crosslinking with 
multifunctional crosslinking monomers nor a disclosure of UV curing. 
U.S. Pat. No. 3,215,671, issued Nov. 2, 1965 to Melby, discloses 
crosslinking oxymethylene homopolymers using, in one embodiment, from 0.5 
to 20% by weight of a polyunsaturated compound (multifunctional acrylates 
are disclosed) and a photoinitiator under UV light. See, e.g., column 2, 
lines 21-25 and 63-72. The crosslinked product is characterized as having 
an extent of crosslinking: 
". . . such that at least 30% of the polymer composition remains 
undissolved when a film thereof of 5-8 mils thickness is immersed in one 
hundred times its weight of boiling dimethylformamide for two minutes", 
column 2, lines 30-39, or such that: 
". . . at least one covalently bonded linkage [is present] between 
catenarian carbon atoms of different polyoxymethylene chains for each for 
polyoxymethylene polymer molecules", 
column 2, lines 40-44. Melby's crosslinked oxymethylene homopolymers appear 
to be crystalline materials; see from column 5, line 67 to column 8, line 
10. In no case are they characterized as noncrystalline. 
SUMMARY OF THE INVENTION 
Terpolymers of trioxane, 1,3-dioxolane and from about 2 to about 20 weight 
percent, and preferably from about 5 to about 10 weight percent, of a 
formal of a monoethylenically unsaturated aliphatic diol having at least 4 
carbon atoms in its main chain, i.e., the chain containing the ethylenic 
unsaturation and bearing the diol's hydroxy groups, such as 
4,7-dehydro-1,3-dioxepin (2-butene-1,4-diol formal) and the like, which 
are non-crystalline at room temperature (about 25.degree. C.) or above 
have now been prepared and found to have useful properties neither present 
in prior art materials nor contemplated by the prior art. These 
terpolymers are non-crystalline at room temperature or above by virtue of 
having higher dioxolane contents than copolymers or terpolymers hitherto 
contemplated by the prior art, i.e., dioxolane contents greater than 65 
weight percent and less than about 75 weight percent, e.g. about 70 weight 
percent, and have intrinsic viscosities (IV) of from about 0.5 to about 
1.5, and preferably from about 0.8 to about 1.0, as measured by standard 
viscometry methods, e.g., in o-chlorophenol. When admixed with 
multifunctional acrylates or similarly-performing multifunctional 
crosslinking monomers and a photosensitzer or UV initiator and cured to an 
insoluble, non-tacky, rubbery state using UV radiation, they can form 
useful crosslinked films or be cryogenically ground to a suitable small 
particle size for blending with conventionally prepared crystalline 
oxymethylene homo-, co- and terpolymers to improve the impact properties 
of the crystalline polymer in articles molded from such blends. 
It is therefore an object of the invention to provide novel acetal 
terpolymers. 
It is also an object of this invention to provide novel UV curable 
terpolymers of trioxane, 1,3-dixolane and a formal of a monoethylenically 
unsaturated aliphatic diol having at least 4 carbon atoms in its main 
chain, such terpolymers being non-crystalline at room temperature or above 
and having higher dioxolane contents than hitherto contemplated in the 
prior art. 
A further object of this invention is to provide UV curable blends 
comprising such non-crystalline trioxane/1,3-dioxolane/monoethylenically 
unsaturated aliphatic diol formal terpolymers with multifunctional 
acrylates or similarly-performing multifunctional crosslinking monomers. 
Another object of this invention is to provide articles prepared from such 
non-crystalline trioxane/1,3-dioxolane/monoethylenically unsaturated 
aliphatic diol formal terpolymer/multifunctional acrylate or 
similarly-performing multifunctional crosslinking monomer blends. 
A still further object of this invention is to provide blends or admixtures 
of UV cured non-crystalline trioxane/1,3-dioxolane/monoethylenically 
unsaturated aliphatic diol formal terpolymer/multifunctional acrylate or 
similarly-performing multifunctional crosslinking monomer blends with 
crystalline oxymethylene homo-, co- and terpolymers, and articles prepared 
from such blends or admixtures which have improved impact properties. 
These and other objects, as well as the nature, scope and utilization of 
this invention, will become readily apparent to those skilled in the art 
from the following description and the appended claims. 
DETAILED DESCRIPTION OF THE INVENTION 
The Novel UV Curable Non-Crystalline Acetal Terpolymer 
The novel UV curable non-crystalline 
trioxane/1,3-dioxolane/monoethylenically unsaturated aliphatic diol formal 
terpolymers of this invention are preferably prepared by bulk polymerizing 
from about 2 weight percent to about 20 weight percent, and preferably 
from about 5 weight percent to about 10 weight percent, of the 
monoethylenically unsaturated aliphatic diol formal dissolved in a 
solution of trioxane and from at least 65 weight percent to about 75 
weight percent, e.g., about 70 weight percent, of 1,3-dioxolane, these 
weight percentages being based, in each case, on the total weight of the 
three monomers used. 
The polymerization reaction will be carried out under an inert atmosphere, 
e.g., one obtained using dry nitrogen, argon, or the like, or a mixture of 
inert gases, in the presence of a catalytically effective amount of a 
cationic polymerization catalyst, such as 
p-nitrobenzenediazoniumfluoroborate, trifluoromethanesulfonic acid, boron 
trifluoride, a boron trifluoride etherate, or the like, e.g., an amount 
ranging from about 5.times.10.sup.-5 M/1 to about 2.times.10.sup.-2 M/1, 
and preferably from about 1.times.10.sup.-3 M/1 to about 5.times.10.sup.-3 
M/1, based on the volume of the reaction medium (reactants plus any 
solvents or suspending agents employed). 
The conditions under which the polymerization reaction is carried out are 
not critical. This reaction will usually be carried out at room 
temperature and atmospheric for from about 20 to about 30 hours. 
These polymers can also be prepared under the foregoing conditions by 
polymerizing the monoethylenically unsaturated aliphatic diol formal, 
trioxane and 1,3-dioxolane in a solvent, or suspending agent for the 
monomers, e.g., a halogenated hydrocarbon such as methylene chloride, a 
hydrocarbon such as hexane, cyclohexane, nonane or dodecane, an ether, or 
the like, or a mixture of two or more of these or other suitable solvents 
or suspending agents. 
As indicated above, the monoethylenically unsaturated aliphatic diol formal 
termonomer will be one having at least 4 carbon atoms in its main chain. 
Preferably, formals of monoethylenically unsaturated aliphatic diols 
having from 4 to 8 carbon atoms in their main chains, which may be 
unsubstituted or substituted with, for example, one or more aliphatic 
hydrocarbon side chains containing from 1 to about 4 carbon atoms, will be 
used. Included among such monoethylenically unsaturated aliphatic diol 
formal termonomers are 4,7-dehydro-1,3-dioxepin (2-butene-1,4-diol 
formal), 3-pentene-1,4-diol formal, 2-n-hexane- 1,4-diol formal, 
2-(2-ethyl)butene-1,4-diol formal, 3-octene-1,4-diol formal, and the like. 
UV Curable Blends of Non-Crystalline Acetal Terpolymers and Crosslinking 
Monomers 
UV curable blends of the novel non-crystalline 
trioxane/1,3-dioxolane/monoethylenically unsaturated aliphatic diol formal 
terpolymers of this invention will contain from about 1 to about 20 weight 
percent, and preferably from about 5 to about 10 weight percent, of the 
terpolymer admixed with a multifunctional crosslinking monomer, said 
weight percentages being based on the total weight of terpolymer and 
crosslinking monomer used. 
Multifunctional acrylates, methacrylates, itaconates and like acid esters 
of polyols are preferred as the crosslinking monomers. Included among such 
compounds generally are monomers and prepolymers, i.e., dimers, trimers or 
other oligomers, or mixtures or copolymers thereof, of acrylic acid, 
methacrylic acid, itaconic acid and like acid esters of aliphatic polyols 
such as the di- and higher polyacrylates, di- and higher polymethacrylates 
and di- and higher polyitaconates of ethylene glycol, triethylene glycol, 
tetraethylene glycol, tetramethylene glycol, trimethylolethlane, 
butanediol, pentaerythritol, dipentaerythritol, tripentaerythritol, other 
polypentaerythritols, sorbitol, d-mannitol, diols of unsaturated fatty 
acids, and the like. 
Specific examples of such multifunctional acrylates, methacrylates and 
itaconates include trimethylolpropane triacrylate, trimethylolethane 
triacrylate, trimethylolpropane trimethacrylate, trimethylolethane 
trimethacrylate, tetramethylene glycol dimethacrylate, tetraethylene 
glycol diacrylate, pentaerythritol diacrylate, pentaerythritol 
triacrylate, pentaerythritol tetraacrylate, dipentaerythritol diacrylate, 
dipentaerythritol triacrylate, dipentaerythritol tetraacrylate, 
dipentaerythritol pentaacrylate, dipentaerythritol hexacrylate, 
tripentaerythritol octaacrylate, pentaerythritol dimethacrylate, 
pentaerythritol trimethacrylate, dipentaerythritol dimethacrylate, 
dipentaerythritol tetramethacrylate, tripentaerythritol octamethacrylate, 
pentaerythritol diitaconate, dipentaerythritol triitaconate, 
dipentaerythritol pentaitaconate, dipentaerythritol hexaitaconate, 
ethylene glycol dimethacrylate, 1,3-butanediol diacrylate, 1,3-butanediol 
dimethacrylate, 1,4-butanediol diitaconate, sorbitol triacrylate, sorbitol 
tetraacrylate, sorbitol tetramethacrylate, sorbitol pentaacrylate, 
sorbitol hexacrylate, dipropylene glycol dimethacrylate, polyethylene 
glycol dimethacrylate, polypropylene glycol diacrylate, substituted 
alkylene glycol diacrylates, dimethacrylates and diitaconates, e.g., 
halogen-substituted propylene glycol dimethacrylates, bisphenol A alkylene 
oxide adduct diacrylates, dimethacrylates and diitaconates such as 
bisphenol A/ethylene oxide adduct dimethacrylates, hydrogenated bisphenol 
A/alkylene oxide adduct diacrylates, dimethacrylates and diitaconates such 
as hydrogenated bisphenol A/propylene oxide adduct diiacrylates, 
urethane-modified polyacrylates, polymethacrylates and polyitaconates 
having two or more acryloyloxy, methacryloyloxy or itaconoyloxy groups in 
the molecule, prepared by reacting a diisocyanate with a compound 
containing two or more alcoholic hydroxyl groups and then reacting the 
resulting terminal isocyanate group-containing compound with an alcoholic 
hydroxy group-containing acrylate, methacrylate or itaconate; epoxy 
polyacrylates, polymethacrylates and polyitaconates having two or more 
acryloyloxy, methacryloyloxy or itaconoyloxy groups in the molecule, 
prepared by reacting a polyepoxide compound containing two or more epoxy 
groups with acrylic, methacrylate or itaconic acid, and the like, as well 
as mixtures thereof. 
The UV curable blend will also contain from about 0.05 to about 20 weight 
percent, and preferably from about 0.5 to about 10 weight percent, based 
on the total weight of non-crystalline 
trioxane/1,3-dioxolane/monoethylenically unsaturated aliphatic diol formal 
terpolymer and multifunctional crosslinking monomer used, of a 
photosensitizer or UV initiator. 
The photosensitizer used can be any of the compounds conventionally 
employed to promote UV curing of unsaturated polymeric materials, 
including, for example, ketals such as benzyldimethyl ketal; benzoins such 
as benzoin and alkyl and aryl ethers of benzoin, e.g., benzoin methyl 
ether, benzoin ethyl ether, benzoin isopropyl ether and benzoin isobutyl 
ether; -methylbenzoin; anthraquinones such as 9,10-anthraquinone, 
1-chloroanthraquinone, 2-chloroanthraquinone, 2-ethylanthraquinone; 
acetophenones such as acetophenone, 2-, 3- or 4-bromoacetophenone, 
2,2-di-ethoxyacetophenone and 3- or 4-allyl acetophenone; benzophenones 
such as benzophenone, p-chlorobenzophenone, and 2-, 3- or 
4-methoxybenzophenone; fluorenone; propiophenones such as 
2-hydroxy-2-methylpropiophenone, 
1-(4-isopropylphenyl)-2-hydroxy-2-methylpropiophenone; suberones such as 
dibenzosuberone, sulfur-containing compounds such as diphenyl disulfide, 
tetramethylthiuram disulfide, xanthone and thioxanthone; pigments such as 
methylene blue, eosine, fluoresceine; or the like, as well as mixtures 
thereof. 
UV cure can be effected using any of a variety of known ultraviolet light 
sources: sun lamps, chemical lamps, low pressure and high pressure mercury 
vapor lamps, carbon arc lamps, xenon lamps, metal halide lamps, or the 
like, and will generally be carried out, using a source of 20 to 200 
mW/cm.sup.2, for from about 1 second to 15 minutes. 
UV Cured Non-Crystalline Acetal Terpolymer Blends With Crystalline 
Oxymethylene Homo-, Co- and Terpolymers 
Crystalline oxymethylene polymers useful in preparing the blends of this 
invention are well known in the art. Such polymers are characterized in 
general as having recurring oxymethylene groups or units. The term 
oxymethylene polymer as used herein is intended to include any 
oxymethylene polymer having oxymethylene groups which comprise at least 
about 50 percent, and generally at least about 85 percent, of the 
polymer's recurring units, i.e., homopolymers, copolymers, terpolymers and 
the like. 
Typically, oxymethylene homopolymers, or polyformaldehydes or 
[poly(oxymethylenes)], are prepared by polymerizing anhydrous formaldehyde 
or trioxane, a cyclic trimer of formaldehyde. For example, high molecular 
weight polyoxymethylenes have been prepared by polymerizing trioxane in 
the presence of certain fluoride catalysts, such as antimony fluoride. 
Polyoxymethylenes may also be prepared in high yields and at rapid 
reaction rates by the use of catalysts comprising boron fluoride 
coordination complexes with organic compounds, as described in U.S. Pat. 
No. 2,898,506 to Hudgin et al. 
Oxymethylene homopolymers are usually stabilized against thermal 
degradation by end-capping with, for example, ester or ether groups such 
as those derived from alkanoic anhydrides, e.g., acetic anhydride, or 
dialkyl ethers, e.g., dimethyl ether, or by incorporating stabilizer 
compounds into the homopolymer, as described in U.S. Pat. No. 3,133,896 to 
Dolce et al. 
Oxymethylene copolymers which are especially suitable for use in the blends 
of this invention will usually possess a relatively high level of polymer 
crystallinity, i.e., about 70 to 80 percent or higher. These preferred 
oxymethylene copolymers have repeating units which consist essentially of 
oxymethylene groups interspersed with oxy(higher)alkylene groups 
represented by the general formula: 
##STR1## 
wherein each R.sub.1 and R.sub.2 is hydrogen or a lower alkyl group, each 
R.sub.3 is a methylene, oxymethylene, lower alkyl-substituted methylene or 
lower alkyl-substituted oxymethylene group, and n is an integer from zero 
to three, inclusive. Each lower alkyl group preferably contains one or two 
carbon atoms. 
Oxymethylene groups generally will constitute from about 85 to about 99.9 
percent of the recurring units in such copolymers. The oxy(higher)alkylene 
groups incorporated into the copolymer during copolymerization produce the 
copolymer by the opening of the ring of a cyclic ether or cyclic formal 
having at least two adjacent carbon atoms, i.e., by the breaking of an 
oxygen-to-carbon linkage. 
Copolymers of the desired structure may be prepared by polymerizing 
trioxane together with from about 0.1 to about 15 mol percent of cyclic 
ether or cyclic formal having at least two adjacent carbon atoms, 
preferably in the presence of a catalyst such as a Lewis acid (e.g., 
BF.sub.3, PF.sub.5, and the like) or other acids (e.g., HClO.sub.4, 1% 
H.sub.2 SO.sub.4, and the like), ion pair catalysts, etc. 
In general, the cyclic ethers and cyclic formals employed in making these 
preferred oxymethylene copolymers are those represented by the general 
formula: 
##STR2## 
wherein each R.sub.1 and R.sub.2 is hydrogen or a lower alkyl group, each 
R.sub.3 is a methylene, oxymethylene, lower alkyl-substituted methylene or 
lower alkyl-substituted oxymethylene group, and n is an integer from zero 
to three, inclusive. Each lower alkyl group preferably contains one or two 
carbon atoms. 
The cyclic ether and cyclic formal preferred for use in preparing these 
preferred oxymethylene copolymers are ethylene oxide and 1,3-dioxolane, 
respectively. Among the other cyclic ethers and cyclic formals that may be 
employed are 1,3-dioxane, trimethylene oxide, 1,2-propylene oxide, 
1,2-butylene oxide, 1,3-butylene oxide, 1,4-butanediol formal, and the 
like. 
Oxymethylene copolymers produced from the preferred cyclic ethers have a 
structure composed substantially of oxymethylene and oxy(lower)alkylene, 
preferably oxymethylene, groups, and are thermoplastic materials having a 
melting point of at least 150.degree. C. They normally are millable or 
processable at temperatures ranging from 180.degree. C. to about 
200.degree. C., and have a number average molecular weight of at least 
10,000 and an inherent viscosity of at least 1.0 (measured at 60.degree. 
C. in a 0.1 weight percent solution in p-chlorophenol containing 2 weight 
percent of .alpha.-pinene). 
These oxymethylene copolymers preferably are stabilized to a substantial 
degree prior to incorporating them into the blends of this invention. This 
can be accomplished by degradation of unstable molecular ends of the 
polymer chains to a point where a relatively stable carbon-to-carbon 
linkage exists at each end of each chain. Such degradation may be effected 
by hydrolysis, as disclosed, for example, in U.S. Pat. No. 3,219,623 to 
Berardinelli. 
The oxymethylene copolymer may also be stabilized by end-capping, again 
using techniques well known to those skilled in the art. End-capping is 
preferably accomplished by acetylation with acetic anhydride in the 
presence of sodium acetate catalyst. 
A particularly preferred class of oxymethylene copolymers is commercially 
available from Hoechst-Celanese Corporation under the designation 
CELCON.RTM. acetal copolymer, and especially preferred is CELCON.RTM. M25 
acetal copolymer, which has a melt index of about 2.5g/10 min. when tested 
in accordance with ASTM D1238-82. 
Oxymethylene terpolymers having oxymethylene groups, oxy(higher) alkylene 
groups such as those corresponding to the above-recited general formula: 
##STR3## 
and a different, third group interpolymerizable with oxymethylene and 
oxy(higher)alkylene groups may be prepared, for example, by reacting 
trioxane, a cyclic ether or cyclic acetal and, as the third monomer, a 
bifunctional compound such as a diglycide of the formula: 
##STR4## 
wherein Z represents a carbon-to-carbon bond, an oxygen atom, an oxyalkoxy 
group of 1 to 8 carbon atoms, inclusive, preferably 2 to 4 carbon atoms, 
an oxycycloalkoxy group of 4 to 8 carbon atoms, inclusive or an 
oxypoly(lower alkoxy) group, preferably one having from 2 to 4 recurring 
lower alkoxy groups each with 1 or 2 carbon atoms, for example, ethylene 
diglycide, diglycidyl ether and diethers of 2 mols of gylcide and 1 mol of 
formaldehyde, dioxane or trioxane, or diethers of 2 mols of glycide and 1 
mol of an aliphatic diol with 2 to 8 carbon atoms, advantageously 2 to 4 
carbon atoms, or a cycloaliphatic diol with 4 to 8 carbon atoms. 
Examples of suitable bifunctional compounds include the diglycidyl ethers 
of ethylene glycol; 1,4-butanediol; 1,3-butanediol; cyclobutane-1,3-diol; 
1,2-propanediol; cyclohexane-1,4-diol and 
2,2,4,4-tetramethylcyclobutane-1,3-diol, with butanediol diglycidyl ethers 
being most preferred. 
Generally, when preparing such terpolymers, ratios of from 99.89 to 89.0 
weight percent trioxane, 0.1 to 10 weight percent of the cyclic ether or 
cyclic acetal and 0.01 to 1 weight percent of the bifunctional compound 
are preferred, these percentages being based on the total weight of 
monomers used in forming the terpolymer. Ratios of from 99.85 to 89.5 
weight percent of trioxane, 0.1 to 10 weight percent of cyclic ether or 
cyclic acetal and 0.05 to 0.5 weight percent of diglycidyl ether are 
particularly preferred, these percentages again being based on the total 
weight of monomers used in forming the terpolymer. 
Terpolymer polymerization may be carried out according to known methods of 
solid, solution or suspension polymerization. As solvents or suspending 
agents, one may use inert aliphatic or aromatic hydrocarbons, halogenated 
hydrocarbons or ethers. 
Trioxane-based terpolymer polymerization is advantageously carried out at 
temperatures at which trioxane does not crystallize out, that is, at 
temperatures within the range of from about -50.degree. C. to about 
+100.degree. C. 
Cationic polymerization catalysts, such as organic or inorganic acids, acid 
halides and, preferably, Lewis acids, can be used in preparing the 
terpolymers. Of the latter, boron fluoride and its complex compounds, for 
example, etherates of boron fluoride, are advantageously used. Diazonium 
fluoroborates are particularly advantageous. 
Catalyst concentration may be varied within wide limits, depending on the 
nature of the catalyst and the intended molecular weight of the 
terpolymer. Thus, catalyst concentration may range from about 0.0001 to 
about 1 weight percent, and preferably will range from about 0.001 to 
about 0.1 weight percent, based on the total weight of the monomer 
mixture. 
Since catalysts tend to decompose the terpolymer, the catalyst is 
advantageously neutralized immediately after polymerization using, for 
example, ammonia or methanolic or acetonic amine solutions. 
Unstable terminal hemiacetal groups may be removed from the terpolymers in 
the same manner as they are from other oxymethylene polymers. 
Advantageously, the terpolymer is suspended in aqueous ammonia at 
temperatures within the range of from about 100.degree. C. to about 
200.degree. C., if desired in the presence of a swelling agent such as 
methanol or n-propanol. Alternatively, the terpolymer is dissolved in an 
alkaline medium at temperatures above 100.degree. C. and subsequently 
reprecipitated. Suitable alkaline media include benzyl alcohol, ethylene 
glycol monoethyl ether, or a mixture of 60 weight percent methanol and 40 
weight percent water containing ammonia or an aliphatic amine. 
The terpolymers may also be thermally stabilized by degrading unstable 
molecular ends of their chains to a point where a relatively stable 
carbon-to-carbon linkage exists at each end of each chain. Thermal 
stabilization will preferably be carried out in the absence of a solvent 
in the melt, in the presence of a thermal stabilizer. 
Alternatively, the terpolymer can be subjected to heterogeneous hydrolysis 
wherein water, with or without a catalyst, e.g., an aliphatic or aromatic 
amine, is added to a melt of the terpolymer in an amount ranging from 
about 1 to about 50 percent by weight, based on the weight of the 
terpolymer. The resulting mixture is maintained at a temperature in the 
range of from about 170.degree. C. to 250.degree. for a specified period 
of time, and then washed with water and dried or centrifuged. 
A preferred oxymethylene terpolymer is commercially available from 
Hoechst-Celanese Corporation under the designation CELCON.RTM. U10 acetal 
polymer, and is a butanediol diglycidyl ether/ethylene oxide/trioxane 
terpolymer containing about 0.05 weight percent, 2.0 weight percent, and 
97.95 weight percent of repeating units derived from these termonomers, 
respectively, based on the total weight of these termonomers. 
Crystalline oxymethylene polymers admixed with plasticizers, formaldehyde 
scavengers, mold lubricants, antioxidants, fillers, colorants, reinforcing 
agents, light stabilizers and other stabilizers, pigments, and the like, 
can be used in the blends of this invention so long as such additives do 
not materially affect such blends' desired properties, particularly 
enhancement of impact strength, as manifested in articles molded 
therefrom. Such additives can be admixed with the novel low UV cured 
non-crystalline terpolymer, the crystalline oxymethylene polymer or the 
blend of these two materials using conventional mixing techniques. 
Suitable formaldehyde scavengers include cyanoguanidine, melamine and 
melamine derivatives, such as lower alkyl- and amine-substituted 
triazines, amidines, polyamides, ureas, metal oxides and hydroxides, such 
as calcium hydroxide, magnesium hydroxide, and the like, salts of 
carboxylic acids, and the like. Cyanoguanidine is the preferred 
formaldehyde scavenger. Suitable mold lubricants include alkylene 
bisstearamides, longchain amides, waxes, oils, and polyether glycides. A 
preferred mold lubricant is commercially available from Glycol Chemical, 
Inc. under the designation Acrawax C, and is an alkylene bisstearamide. 
The preferred antioxidants are hindered bisphenols. Especially preferred 
is 1,6-hexamethylene bis-(3,5-di -t-butyl-hydroxyhydrocinnamate), 
commercially available from Ciba-Geigy Corp. under the designation Irganox 
259. 
A most preferred oxymethylene copolymer for use in the blends of this 
invention is commercially available from Hoechst-Celanese Corporation 
under the designation CELCON.RTM. M25-04 ac polymer. This oxymethylene 
copolymer has a melt index of about 2.5g/10 min. and contains 0.5 percent 
by weight Irganox 259, 0.1 percent by weight cyanoguanidine, and 0.2 
percent by weight Acrawax C. 
A most preferred oxymethylene terpolymer for use in the blends of this 
invention is commercially available from Hoechst-Celanese Corporation 
under the designation CELCON.RTM. U10-11 acetal polymer. This is the 
previously mentioned CELCON.RTM. U-10 acetal terpolymer stabilized by 0.5 
percent by weight Irganox 259 and 0.1 percent by weight calcium 
ricinoleate. 
The blends of the cured non-crystalline terpolymer and crystalline 
oxymethylene homo-, co- or terpolymer of this invention may be prepared by 
any conventional procedure that will result in a substantially uniform 
blend or admixture of the components. Preferably, dry or melt blending 
procedures and equipment are used. The cured non-crystalline terpolymer, 
which can range from a dry solid to a slightly tacky material, can be dry 
mixed with the crystalline oxymethylene polymer (in the form of pellets, 
chips, flakes, granules or powder), typically at room temperature (about 
25.degree. C.), and the resulting mixture melt blended in any conventional 
type extrusion equipment, which is customarily heated to a temperature of 
from about 170.degree. C. to about 220.degree. C., and preferably from 
about 190.degree. C. to about 210.degree. C. The sequence of addition of 
the components is not critical, and any conventional means may be used to 
form the substantially uniform admixture. 
Preferably, the cured non-crystalline terpolymer and the crystalline 
oxymethylene polymer are dried (either individually or together) before 
being subjected to the blending procedure. Drying can be done in 
desiccated air having a dew point of about -30.degree. C. to -40.degree. 
C. or lower, at a temperature of from about 70.degree. C. to about 
110.degree. C. The drying time will depend primarily on the moisture 
content, drying temperature, and particular equipment employed, but 
typically is from about 2 to about 6 hours or more. If the drying is 
conducted for longer periods of time, such as overnight, the drying 
temperature should preferably be about 70.degree. C. to about 85.degree. 
C. In general, any conventional drying procedure can be used to reduce the 
moisture content to below about 0.1 weight percent, based on the total 
weight of the cured non-crystalline terpolymer and the crystalline 
oxymethylene polymer, preferably below about 0.05 weight percent, and most 
preferably below about 0.01 weight percent. 
If conventional mold lubricants, plasticizers, fillers (particularly glass 
in the form of filaments or strands, beads, dust or microbubbles, any of 
which forms can be sized or otherwise combined with coupling agents), 
nucleating agents, antioxidants, formaldehyde scavengers, chain scission 
inhibitors, ultraviolet light inhibitors and similar molding additives 
have not previously been added to the cured non-crystalline terpolymer or 
the crystalline oxymethylene polymer during the processing of these 
individual components of the blend, i.e., before they are admixed with 
each other, they may be added at this time. 
The uniform admixture resulting from the blending procedure is then 
comminuted mechanically, for example by chopping, pelletizing or grinding, 
into granules, pellets, chips, flakes or powders, and processed in the 
thermoplastic state, for example by injection molding or extrusion molding 
into shaped articles, including bars, rods, plates, sheets, films, 
ribbons, tubes, and the like. 
Preferably, the comminuted blend is dried again, in the manner discussed 
above, prior to being molded.

In order that those skilled in the art can more fully understand this 
invention, the following examples are set forth. These examples are given 
solely for purposes of illustration, and should not be considered as 
expressing limitations unless so set forth in the appended claims. All 
parts and percentages are by weight, unless otherwise stated. 
EXAMPLE I 
Thirty-five ml of freshly distilled 1,3-dioxolane are injected into a 
clean, dry 50 cc reactor tube which is continuously purged with dry 
nitrogen gas. Next, 5 ml of 4,7-dehydro-1,3-dioxepin are injected, and the 
reactor tube is transferred to an oil bath maintained at approximately 
52.degree. C. while maintaining the dry nitrogen purge. Fifteen ml of 
freshly distilled trioxane are then added, followed by 1.times.10.sup.-3 
mol/liter of a nitromethane solution of 
p-nitrobenzenediazonium-fluoroborate (previously prepared by adding 5 ml 
of nitromethane to 0.06 gram of p-nitrobenzendiazoniumfluoroborate). The 
monomer solution becomes viscous over an approximately 20 hour period. 
Polymerization is allowed to continue for 20 hours. The reactor tube is 
then broken at liquid nitrogen temperature and the polymer mass removed 
and admixed with 100 ml of methylenechloride in a 500 ml beaker. This 
mixture is then allowed to shake for 24 hours on a shake table. The 
resulting viscous solution is added to 1000 ml of cold ethanol and stirred 
with a mechanical shaft stirrer at 400 rpm for 15 minutes. 
The resulting two-phase mixture is placed in an ice bath and let stand for 
one hour, after which time a white, viscous polymer mass settles. The 
solvent is decanted and the polymer mass is then dried in a hood. 
NMR analysis indicates that the polymer contains 24 mol percent trioxane, 
72 mol percent 1,3-dioxolane and 4 mol percent 4,7-dehydro-1,3-dioxepin. 
The polymer has the following physical properties: 
Melting Point: 18.degree. C. 
IV: 0.7. 
EXAMPLE II 
0.54 Gram of a trioxane/1,3-dioxolane/4,7-dehydro-1,3-dioxepin terpolymer 
prepared as described in Example I above and 0.05 gram of hexanediol 
diacrylate are dissolved in 3cc of nitromethane at room temperature. Next, 
0.006 gram of benzoin isobutyl ether is added, and after removing the 
nitrobenzene solvent in a vacuum oven, the reaction mixture is subjected 
to ultraviolet light from a Radiation Polymer Company UV Processor for 5 
minutes. A crosslinked polymer is obtained, as determined by its lack of 
solubility in methylene chloride. 
EXAMPLES III and IV 
The procedure of Example II is repeated in every detail except for the 
amounts of reactable materials and photoinitiator employed: 
______________________________________ 
Reactant Example III Example IV 
______________________________________ 
Terpolymer of 1.0 gram 1.0 gram 
Example I 
1,6-Hexanediol 0.1 gram 0.1 gram 
diacrylate 
Benzoin iso- 0.05 gram 0.01 gram 
butyl ether 
______________________________________ 
In each case, a crosslinked polymer is obtained, as determined by its lack 
of solubility in methylene chloride. 
EXAMPLES V-VII 
The procedure of Example II is again repeated in every detail except for 
the following. Trimethylolpropane triacrylate is used as the 
multifunctional crosslinking monomer, and the amounts of this monomer, the 
terpolymer and the photoinitiator employed are as follows: 
______________________________________ 
Reactant Example V Example VI Example VII 
______________________________________ 
Terpolymer of 
1.0 gram 1.0 gram 1.0 gram 
Example I 
Trimethylolpro- 
0.1 gram 0.1 gram 0.5 gram 
panetriacrylate 
Benzoin isobutyl 
0.05 gram 0.01 gram 0.05 gram 
ether 
______________________________________ 
Once again, crosslinked polymers are obtained, as determined by their lack 
of solubility in methylene chloride. 
EXAMPLE VIII 
A partially crosslinked polymer is first prepared by reacting 1 gram of a 
trioxane/1,3-dioxolane/4,7-dehydro-1,3-dioxepin terpolymer prepared as 
described in Example I above with 0.05 gram of hexanediol diacrylate in 
the presence of 0.05 gram of benzoin iosbutyl ether in the manner 
described in Example II above. 
Blends of this partially crosslinked material with 5, 10, 5, 20, 25 and 
30%, based on the total weight of the blend, of CELCON.RTM. acetal 
copolymer (Hoechst-Celanese Corporation) are then prepared by mixing the 
respective materials, in granular form (after drying overnight at 
75.degree. C.), at room temperature and then blending the resulting 
uniform mixtures in an extruder at 190.degree.-210.degree. C. 
Improved impact strength molding resins are obtained. 
The above discussion of this invention is directed primarily to preferred 
embodiments and practices thereof. It will be readily apparent to those 
skilled in the art that further changes and modifications in the actual 
implementation of the concepts described herein can easily be made without 
departing from the spirit and scope of the invention as defined by the 
following claims.