CA2142849A1 - A process for preparing high impact strength poly(1,4-cyclohexylenedimethylene terephthalate)/ionomer blends - Google Patents

Abstract

This invention relates to a process for preparing poly(1,4-cyclohexylenedimethylene terephthalate)/ionomer compositions which exhibit high impact strength and to articles made therefrom. The process involves melt blending poly(1,4-cyclohexylenedimethylene terephthalate) with an ionomer of ethylene, an unsaturated carboxylic acid selected from the group consisting of acrylic acid and methacrylic acid wherein the carboxylic acid groups are neutralized with zinc or sodium ions, and an alkyl acrylate, at a shear rate of 3500 to 7000 reciprocal seconds; and thermoforming the blend into an article.

Description

~ O 94/06863 P ~ /US93/07868 2142~-19 A PROCESS FOR P ~ P~iRING ~IG~ I~$PACT STRE~NG
POLY(1,4-CYCLOE~CYLE2n~DI~BlErYL~2r5 TE~EP~ Al~TE~IO~O~lE~ RL~DS
.
FIELD OF THE INVENTXON
This invention relates to a process for preparing poly(l,4-cyclohexylenedimethylene terephthalate)~ionomer '-compositions which exhibit high impact strength and to ' articles made therefrom. The process involves melt blending poly(l,4-cyclohexylenedimethylene terephthalate) (PCT) with an ionomer of ethylene, an unsaturated car~oxylic acid selected from the group consisting of acrylic acid and methacrylic acid wherein ; the carboxylic acid groups are neutralized with zinc or sodium ions, and an alkyl acrylate, at a shear rate of ~' 3500 to 7000 reciprocal seconds; and thermoforming the blend into an article.

BACKGM UND OF TH~ INVENTION
~ Thermoplastic polyesters based on terephthalic acid and diols such as ethylene glycol and 1,4-cyclohexanedimethanol hav- proven to be very desirable~for~injection molding~artic~les for high strength applicat~ions.~ Because~many of such articles 2~5 ~must~withstand considerable temperature'changes andxor ~physical abuse, it is customary to blend ~`
po1y(1,4-cyc}ohexylenedimethylene terephthalate) with other polymers to improve its impact resistance as shown ;
- by notched Izod impact values. There are advantages, ~ how'evér, in'''keeping~'PCT;as the matrix material in PCT~polymer blends and those are to retain tensile strength, flexural modulus, elongation percent, weather resistance and h-at deflection temperature. ~"
Thermoplastic compositions exhibiting high impact strength are found in U.S. Pat. Nos. 3,435,0~3, ~"
, ~
~ 4,680,344, 4,172,859 and 4,753,980, and in PCT

~ ' ~ . ,, ~V09~6863 PCT/US93/0~868 ~ ~L 4~

Application No. wo 92~03505. U.s. Pat. No. 3,435,093 discloses blends of polyethylene terephthalate ~and alpha-olefin~alpha-beta unsaturated carboxylic acid copolymers wherein the carboxylic acid groups are 0-100%
neutralized by metal cations such as sodium, potassium, calcium, magnesium, zinc and lead. Moreover, the -~
polyethylene terephthalate is present in an amount of between 55 to 95 weight percent of the blend. Izod impact values of blends indicated in the Examples of ;~
U.S. Pat. No. 3,435,093 range from 27.8 J~m to 59.8 J~m `~
at 23C.
U.S. Pat. No. 4,680,344 discloses blends containing a linear polyester and at least 60 weight percent of alpha-olefin~alpha-beta-ethylenically unsaturated ~carboxylic acid ionomer neutralized with inc, calcium, or magnesium.; No~third comonomer is present. Izod impact values of blends indicated in the Examples of U.S. Pat. No. 4,680,344 range from 26.7 J~m to 1308 J~m at 23C.
20~ ~ U.S. Pat. No. 4,172,859 discloses multiphase . ,, ~
thermoplastic molding aompositions containing 60-99 weight percent of polyester matrix resin, and 1-40 weight pèrcent of ionomer having a particle size in the range of 0.1-3.0 microns.~ The compositions are prepared using a multi-screw extruder to generate~high shear.
U.S. Pat. No. 4,172,859, however, gives no indication of which shearing parameters are critical and no direction ~-as to which of many shearing block designs are likely to - ~ be successful to acoomplish a shear rate of at least 3500 reciprocal seconds which the present inventors have -~ determined to be critical.
U,S. Pat. No. 4,753,980 discloses toughened thermoplastic polyester compositions comprising 6~-97 weight percent of a polyester and 3-40 weight percent of ,, ' ~

.. ...

~'0 94~06863 PCT/~'S93/07868 8 ~ ~ ~

an ethylene copolymer such as ethylenexmethacrylate~
glycidyl methacrylate.
PCT Application No. Wo 92~03505 discloses a semi-crystalline thermoplastic molding composition containing 60 to 90 weight percent of a polyester resin and 10 to 40 weight percent of an ionomer consisting of ethylene, an alkyl acrylate and an unsaturated carboxylic acid. The ionomer has from 20% to 80% of the carboxylic acid groups neutralized with zinc, cobalt, nickel, aluminum or copper (II).
In contrast, the present inventors have ;
unexpectedly discovered a process for preparing superior impact resistant thermoplastic polyester molding compositions as determined by notrhed Izod impact values which are double the impact values found in the previously mentioned patents. The process involves melt blending poly(1,4-cyclohexylenedi~ethylene terephthalate) with an ionomer of ethylene, an `
unsaturated carboxylic acid selected from the group consisting of acrylic acid and methacrylic acid wherein the carboxylic acid groups are neutralized with zinc or sodium ions, and an alkyl acrylate, at a critical shear rate of 3500 to 7000 reciprocal seconds; and forming the biand into an article. High impact strength is obtained even though the inherent viscosity of the poly(l,4-cyclohexylenedimethylene terephthalate) polyester component is significantly reduced due to the high shearing action.
The high ~hearing process of this invention which is used to improve the impact strength of a polyester thermoplastic composition is contrary to the teachings of U.S. Pat. No. 4,780,506. Such patent teaches, in column 2, lines 6 to 13 that high shear blending of ~
polyester~polycarbonate blends with impact modifiers ~-leads to unpredictable results and tran5esterification ~o~/06863 PCT/US93/~786~

,~.

which can be minimized by the use of inhibitors and~or by lowering the shear level.
, .
SU~ARY OF THE_ INVENTION
It is therefore an object of the present invention to improve the impact properties of `
poly(1 4-cyclohexylenedimethylene terephthalate)~ionomer ~:`
blends. .
Another object of the invention is to provide a process for preparing poly~l 4-cyclohexylenedimethylene terephthalate)~ionomer blends under conditions of high ~
shear. :.
A further object of the invention is to provide poly(1 4-cyclohexylenedimethylene terephthalate)~ionomer blends which exhibit excellent mechanical properties . such as impact resîstance stress crack resistance and heat resistance, and which display excellent melt : flowability at the time of molding thereof.
These and other objects are accomplished herein by 20: ~:a~process for preparing a polytl 4-cyclohexylenedimethylene terephthalate)~ionomer : blend which exhibits high impact strength comprising:
melt blending A) 7:0 to 90 weight percent of a polyester which ;-comprises (1) a dicarboxylic acid component consisting --:; essentially of repeat units from terephthalic acid and .t2) a diol component consisting essentially of répeat units from 1~ to 100 mole percent 1~4-cyclohexanedimethanol and from 0 to 85 mole percent .~ ethylene glycol, based on 100 mole percent dicarboxylic 1:
.acid and lQO mole percent diol said polyester having an ~;~: inherent viscosity of 0.4 to 1.5 dl~g; and : (B) 30.0 to 10.0 weight percent of an ionomer !;
35: comprising repeat units from 80 to 95 weight percent of , ' ' .:

~'O 94/06863 P ~ /~'S93/07X68 21 ~.~! 8 - S - .

ethylene and 5 t~ 20 weight percent of an unsaturated carboxylic acid selected from the group consisting of acrylic acid and methacrylic acid, and the carboxylic acid groups being neutralized to the extent of 40 to 95 percent with zinc or sodium ions; wherein the combined weights of (A) and (B) total 100 percent and the -blending is conducted in an extruder capable of -~
- providing a shear rate of 3500 sec~1 to 6000 sec~l; and tII) forming the blend into an article.
'`i`~
DESCRIPTION OF THE INVENTION ,`.
Component (A~ of the present invention is a polyester which contains repeat units from mixture;s of terephthalic acid, 1,4-cyclohexanedimethanol and - 15 ethylene glycol, based on 100 mole percent dicarboxylic acid~and 100 mole percent diol. The dicarboxylic acid -~~~
co~ponent of the polyester (A) consists essentially of repeat units from terephthalic acid. The diol component of~the polyester consists essentially of 15 to 100 O~ weight percent 1,4-cyclohexanedimethanol~ and 0 to 85 weight~pèrcent ethylene glycol. Preferably, the diol portion consists of 20 to 70 weight percent ethylene `~
glycol and 80 to O~weight percent 1,4-cyclohexanedimethanol. The term l'consists ~essentially of" means that in addition to the terephthalic ac~id, 1,4-cyclohexanedimethanol and ethylene glycol, other dicarboxylic acids and diols may be presentjlin the poly,ester provided that the basic and essential characteristids of the polyester are not - 30 materially affected thereby.
-~ For example, the polyester, component (A), may optionally be modified with up to 3 mole percent, based `
on lOO mole percent dicarboxylic acid, of one or more different dicarboxylic acids other than terephthalic acid or suitable synthetic equivalents. Such additional ~094/(~6X63 PCT/US93/07868 ?,~4~t~ ~;

dicarboxylic acids include aromatic dicarboxylic acids- ;`
preferably having 8 to 14 carbon atoms, alipha~ic `;~
dicarboxylic acids preferably having 4 to 12 carbon atoms, or cycloaliphatic dicarboxylic acids preferably having 8 to 12 carbon atoms. Examples of dicarboxylic acids to be included with terephthalic acid are:
phthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid, cyclohexanedicarboxylic acid, cyclohexanediacetic acid,~-diphenyl-4,4'-dicarboxylic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and the;~
like. -~
In addition, the polyester may optionally be modified with up to 3 mole percent, based on 100 mole percent diol, of one or more different diols other than 1,4-cyclohexanedimethanol and ethylene glycol. Such -~additional diols include cycloaliphatic diols preferably having 6 to ~5 carbon atoms or aliphatic diols preferably having 3 to 8 carbon atoms. Examples of such diols ta be included with 1,4-cyclohexanedimethanol and ~; ethylene glycol are: propane-1,3-diol, butane-1,4-diol, i;
pentane-1,5-dio1, hexane-1,6-diol, 3-methylpentanediol-(2~,4), 2-methylpentanediol-(1,4), - 2,2;,4-trimethylpentane-diol-(1,3), 2_ thylhexanediol-(1,3), 2,2-diethylpropane-diol-~1,3), hexanediol-(1,3),~1,4-di-(hydroxyethoxyl-benzene, 2,2-bis-(4-hydroxycyclohexyl)-propane, 2,4-dihydroxy-1,1,3,3-tetramethyl-cyclobutane, 2,2-bis-(3-hydrloxyèthoxyphenyl) propane~, ~
2,2-bis-(4-hydroxypropoxyphenyl)-propane, and the like. ~-:
Polyesters useful as component (A) have an inherent viscosity of 0.4 to 1.5 dl~g. Preferably, the polyesters have an inherent viscosity of 0.5 to l.l ~;~
dl~g. ~olyesters comprising substantially only `
1,4-cyclohexanedimethanol, ethylene glycol and ~ ' : .~

':

~O9~/06863 PCT/US93/07868 ~
.
2 1 ~ ~

terephthalic acid are preferred for use in the present `
invention. Examples of commercially Available polyesters useful as component A include Ektar PCT-387s, PCTG-5445 and PETG-6763 which are available from Eastman Chemical Company, Kingsport, TN. Ektar PCT-3839 is a homopolymer of crystallized poly~l,4-cyclohexylene-dimethylene terephthalate) having an I.~. of 0.75.
Kodar PCTG-5445 and PETG-6763 are polyesters consisting of terephthalic acid, ethylene glycol and ~0 1,4-cyclohexanedimethanol with an I.V. of 0.75.
The polyesters can be prepared by conventional polycondensation procedures well-known in the art. Such processes include direct condensation of the acid with the glycol or by ester interchange using lower alkyl `~
-~ .
-15 e~ters. The essential components of the polyesters;
e.g., terephthalic acid or dimethyl terephthalate, -`
l~,4-cyclohexanedimethanol and ethylene glycol are commercially available. -Component (B) of the present invention is an ionomer. Ionomers suitable for use in the present ~-~ invention consist of copolymers and terpolymers of ethylene, an unsaturated carboxylic acid selected from the group consisting of acrylic acid and methacrylic -acid and, optionally, an alkyl acrylate ha~ing from 1 to 25~ 8~ carbon atoms in the alkyl group. The carboxyl group-containing copolymers and terpolymers usually are converted at least in part to the salt form or, are neutralized to a certain degree. Such neutralization is obtained by adding to the carboxyl group-con~aining polymeric material a calculated amount of a zinc or sodium salt, for example, zinc acetate or sodium ~
methoxide, and heating the mixture to a temperature ~-below 140C., while thoroughly mixing the materials l-together. T~e resulting partly or completely ,, .

,:

.

~V094/06863 PCT/US93/07868 ,.,.,. ,"

~ 8 - ~;

neutralized carboxylic group-containing polymeric material is know~ generically as an ionomer.
The present inventors have determined through experimentation that cations other than zinc and sodium such as aluminum, potassium and magnesium do not result -in improved impact strength for articles incorporating such carboxyl group-containing copolymers and terpolymers. The ionomer has from 40 to 80 percent of the carboxylic acid groups neutralized with zinc or sodium. Preferably, the ionomer has from 50 to 75 percent of the carboxylic acid groups neutralized with zinc or sodium and most preferably 70 percent. Some of such ionomeric matçrials are available commercially, for example "SURIYN" (trademark) ionomer resins of the E.I.
DuPont de Nemours Company. Particularly preferred ionomers a-re SURLYN 9020 which is a random terpolymer of ethylene~methacrylic acid~isobutyl acrylate neutralized -~
, . . .
with zinc, SURLYN 9721 which is a ethylene~methacrylic acid copolymer neutralized with zinc, SURLYN 8020 which is a random terpolymer of ethylene~methacrylic acid~isobutyl acrylate neutralized with sodium, and SURLYN 8527 which is a ethylene~methacrylic acid copolymer neutralized with sodium.
- The ethylene content of the copolymer or terpolymer is at least 50 weight percent, based on the , ~, .
ethylene~acid copolymer or terpolymer. The unsaturated carboxyiic acid content of the ionomer should fall in `~-the range of from~2 to 20 weight percent, the preferred ;
range being from 5 to 15 weight percent and the most preferred range being from 8 to 12 weight percent, based -on the ionomer to give the best combination of low temperature impact resistance and high temperature resistance. The alkyl acrylate content of the ;
terpolymer is from 2 to 15 weight percent. Preferably `
the alkyl acrylate is n-butyl acrylate or isobutyl ~
~

~ ' ' WO91/0686~ PCT/US93/07868 21ll~8 i9 `

acrylate. Most preferably, the alkyl acrylate is isobutyl acrylate.
Ionomer copolymers of this invention preferably contain repeat units from 80 to 95 weight percent of -ethylene and 5 to 20 weight percent of acrylic acid or methacrylic acid. Ionomer terpolymers of this invention preferably contain repeat units from 70 to 90 weight percent of ethylene, 5 to 15 weight percent of acrylic acid or methacrylic acid, and 5 to 15 weight percent of lo an alkyl acrylate or methacrylate having l to 8 carbon atoms in the alkyl group.
Ethylene~methacrylic acid copolymers partially neutralized with zinc or sodium but which do not contain an alkyl acrylate, for example, isobutyl acrylate, are not as effective as ethylene~methacrylic acid copolymers partially neutralized with zinc or sodium which contain isobutyl~acrylate. The present inventors have determined that the presence of an alkyl acrylate tends to reduce the modulus of the ionomer. Isobutyl ;2Q acrylate,~for example, reduces the modulus of the ;~-.:, ~ ionomer which in turn gives a more favorable ratio of -~- PCT modulus to ionomer modulus. The ratio of PCT
- ~ modulus to ionomer modulus should be greater than lO:1, and preferably greater than 20:1. Thus, the absence of an alkyl acrylate necessarily requires higher ; - concentrations of the ionomer in the polyester~ionomer blend in order to obtain high impact strength.
The ionomer generally is present in the blends of the present invention in an amount of from 10 to 3b weight percent. Consequently, at least 70 weight percent of the blends is PCT. Such critical amounts take into consideration the advantages which exist in keeping PCT as the matrix material. The advantages ~`
include retention of tensile strength, flexural modulus, elongation percentage, and heat deflection temperature.
.. . .

~: ~

W094/06863 PCT/US93/07868 ' 7 ~ 49 Preferably the concentration of ionomer should~be from 15 to 25 weight percent and most preferably from 18 to 22 weight percent.
The compositions of the present invention may be made from a single polyester resin and a single ionomer or from a polyester and a mixture of ionomers.
The process for preparing the polyester~ionomer blends of the present invention involve preparing the polyester and zinc ionomer, respectively, by processes ''~';
as mentioned previously. The polyester and zinc ionomer are dried in an atmosphere of dried air or dried , nitrogen, or under reduced pressure. The polyester and ionomer are blended and subsequently melt blended or c~ompounded in an extruder operated in a manner to ~
provide a~ shear~rate of 3500 sec~l to 7000 sec~l in the -;
melt~phase. Such~shear rate is essential to provide the blends~of this invention with high impact strength.
Preferred extruders are twin screw extruders set up to provide~a~shear rate of 3500 sec~1 to 7000 sec~l. The ~' ionomer(s) are dispersed throughout the polyester as '"
discrete~particles, which particles have a~number ~', average particle size of less-than or equal to ~ micron.
The~;ionomer dispersed pha-se in PCT obtained by this type of~blending has particle diameters of 0.1 to 0.3 ,`
2S m~icrons~
Torque can be u-ed as a measurement of the amount `' ~ of shear being applied to a blend. Higher torque values ~"
-~ i res~lt in mo~elsheari~being applied to a sample. The ';- - ~ highest impact properties are achieved with the blends 30 , of the present invention at the maximum torque attaina~le. The maximum torque attainable by the present,inventors is 102 Joules w,hich translates into 6000~sec~1. The present invention, however, is not limited by a torque value of 102 Joules. In fact, the '~
~35 highest impact properties are achieved with the blends : .

- .

~094/06~63 PCT/US93/07868 -- 2i1~8~ `

at the maximum torque. Higher torque values are ;~
expected to result in even greater notched and unnotched impact streng~h.
The necessary shearing force can be obtained, for example, in an extruder such as a Werner and Pfleiderer ZSK-28mm or ZSK-30mm corotating, intexmeshing twin ~crew extruder, at a melt temperature of 260C. It is important to note that the Werner and Pfleiderer -ZSK-28mm corotating, intermeshing twin screw extruder has at least two different screw designs, a "hard" screw design and a "medium" screw design. The "hard" screw design is a screw configuration which has 215 mm of kneading block length, eight elements which slide on, near the center and end of the screw for mixing and homogenizing the material. Two of the elements are left-handed elements capable of providing a higher shear fie}d. A left-handed screw bushing element is included to back up the flow in the machine to create higher -~
shear.~ The total length of the "hard" screw is 800 mm.
20 ~ Within the 'lhard" screw design, there are infinite settings that would provide the necessary shear. The maximum shear rate obtainable with the ~hard" screw design on the Werner and Pfleiderer ZS~-28mm extruder is 5500~sec~l. Thus, the "hard" screw is appropriately named since it is "hard" on the polymer.
Th-~"mediu:" scréw design has a mixing screw which is the same length as the "hard" screw. The "medium"
- sçrew has 45 mm of k!neading block length, four elements which slide on, near the center and end of the screw for mixing and homogenizing the material. The maximum shear -`~
rate obtainable with the "medium" screw design is less than 3500 sec~l. The present inventors have determined that the impact otrength of blends prepared with the ~-- .
"mediu~ screw design on the Werner and ~fleiderer ZSK-28mm extruder have significa~tly lower Izod impact ':~

O~/06863 PCT/US93/07868 ~ '3 - 12 -values than blends prepared with the "hard" screw design. Moreover, the present inventors have determined that blends prepared on single screw extruders have even .
lower Izod impact values than blends prepared with a Werner and Pfleiderer ZSK-28mm extruder having a "medium" screw design.
Single screw extruders do not provide the necessary shear to prepare blends with high notched impact strength as compared to twin screw extruders. It is -important to note that while the "medium" screw design gives less shearing action than the "hard" screw design, the "medium" screw design gives more shearing action ;~
than a single screw extruder. Moreover, twin screw extruders do not necessarily provide the proper amount of~shear unless the "hard" screw design is employed.
The twin screw configuration required to attain the high~impact compositions of the present invention requires that 25 percent of the screw length contain ,~?
kn-ading blocks~ These kneading blocks are distributed ;-~
in~groups of 2 to 4, for example, and each group is generally ended with a left-handed kneading block to insure tbat the kneading block groups are being ~`
maintained at fulI capacity to maximize their mixing capability. However, other configurations that have at least the minimum length of kneading blocks and , ~ ~
left-handed kneading blocks will provide the desired results. Such configurations provide maximum shear rates, good extensional fiow and backmixing.
Melt te~peratures must bé`at least~as high as~the melting point of the polyester component or sufficiently ~; above the glass transition temperature for an amorphous -~ polyester, which typically is in the range of 260-310C.
Pref~ ably, the melt blending or compounding temperature ~;
is maintained as low as possible within said range. The composition is molded preferably at 260C. to 280C.

.~

~O9~/06863 PCT/US93/07868 2 1 ~

- 13 - -~

under low temperature mold conditions such as 23OC. to provide an amorphous molded specimen. High impact strength is obtained even though the I.V. of the poly(1,4-cyclohexylenedimethylene terephthalate) polyester component has been significantly reduced due to the high shearing action. After completion of the melt compounding, the extrudate is withdrawn in strand form, and recovered according to the usual way such as cutting.
Under melt processing conditions the PCT undergoes molecular weight degradation in the presence of contaminants such as water, thus, it is preferable that the polyester be incorporated in anhydrous form into the blends of the present invention. The blends should also be protected from~moisture prior to melt processing.
Many other ingredients can be added to the - .
compositions of the present invention to enhance the performance properties of the blends. For example, -`
surface lubricants, denesting agents, stabilizers, antioxidants, ultraviolet light absorbing agents, mold release agents, metal deactivators/ colorants such as titanium dioxide and carbon black, nucleating agents - such as polyethylene and polypropylene, phosphate stabilizer~s, fillers, and the like, can be included heroin. All of these additives and the use thereof are well known in the art and do not require extensive discussions. Therefore, only a limited number will be referred to, it being understood that any of these compounds can be used so long as they do not hinder th`e ~-~
present invention from accomplishing its objects. ~-The blends of the present invention serve as excellent starting materials for the production of ``
. .
moldings of all types. Specific applications include -medical parts, appliance parts, automotive parts, tool housings, recreational and utility parts. The molding :-, ~O~/06863 PCT/US93/07868 .~ Ja~
- 14 - ;:

compositions of the present invention are especially useful in applications that require toughness in hard to fill injection molded parts. Additionally, the blends -can be used to prepare extruded sheets for thermoforming applications.
The materials and testing procedures used for the results shown herein are as follows:
Break Elongation: ASTM-D638 Density (gradient tube method): ASTM-D1505 - 10 Flexural Modulus and Flexural Strength: ASTM-790 .,.
Heat Deflection Temperature: ASTM-D648 Melt Flow Index: ASTM-D1238 Tensile Strength and Yield Strength: ASTM-T638 Izod Impact Strength: ASTM-D256. The Izod Impact ~.
~5 Strength Test was repeated three to five times for each ~: materiaI. The letters CB, PB and NB listed under impact -~- :strength have the following~meanings: .
CB - complete break, brittle failure PB - partial break 20 : NB - no break, ductile failure.
Inherent viscosity (I.V.) was measured at 23C.
~; using 0.50 grams of polymer per 100 ml of a solvent ~:~~:. consisting of 60% by weight phenol and 40% by weight tetrachloroethane.
~-~ 25 Ionomer A is a 80~10~10 weight percent terpolymer : consisting of ethylene, isobutyl acrylate and methacrylio acid, respectively, containing 2.63 weight p;.ercent zinc. The,degree of neutralization of the acid is 69%. Flexural Modulus at 23C. is 14,000 psi (100 ;~
NPa). Melt Index at 190C. (gramg per lO minutes) is 1.O. Polyester~Ionomer ratio is lO:l. Ionomer A is ::.
commercially available under the trademark SURLYN 9020 from E:.I. DuPont de Nemours and Company.
Ionomer B is a 80~10~10 weight percent terpolymer consisting of ethylene, isobutyl acrylate and .

~09~tt)6~63 PCT/~S93/07868 2 1 ~

methacrylic acid, respectively, with 70~ of the carboxyl groups neutralized with sodium. Melt Index at l90CC.
(grams per 10 minutes) is 1Ø Polyester/Ionomer ratio is 10:1. Ionomer B is commercially available under the tradename SURLYN 8020 from E.I. DuPont de Nemours and Company.
The invention will be further illustrated by a consideration of the following examples, which are intended to be exemplary of the invention. All parts and percentages in the examples are on a weight basis unless otherwise stated.

A homopolymer of crystallized poly(1,4-cyclohexylenedimethylene terephthalate) having an I.V. of 0.75 was dried at 15~C. for 16 hours in desiccant air with a dew point S-29C. The PCT was ~
placed in the hopper, under dry N2, of a Werner and -Pfleiderer ZSK-28mm corotating, intermeshing twin screw -extruder having the "hard" screw design. The PCT was ;
melt processed at 295C. under high shear conditions, stranded and pelletized. The I.V. of the PCT was 0.61.
The pelletized PCT was dried at 100C. for 8 hours - in desiccant air with a dew point S-29C. and injection ~- 25 molded on a Boy 22S injection molding machine using a `;
melt temperature of 295C~ and a mold temperature of 23C. to provide an amorphous test specimen. The I.V. `
of the PCT after molding was 0.55. The impact i properties , thle PCTiare summari2ed in Table I.

!-:, ~O~/06863 PCT/US93/07868 `
" .~ .

The PCT of Example 1 was dried at 150C. f~r 16 hours in desiccant air with a dew point ~-29C. -~
Ionomer A was dried at 60OCc for 16 hours in desiccant air with a dew point <-29C. ~he PCT and Ionomer A were pellet blended in a polyethylene bag such that the `~
concentration of Ionomer A was 20 weight percent. The PCT~Ionomer A blend was placed in the hopper, under dry ~;
N2, of a Werner and Pfleiderer ZSK-28mm cor~tating, intermeshing twin screw extruder having the "hard" screw ~`
design. The blend was melt processed at 2950C. under ~
high shear conditions, stranded and pelletized. ~-The pelletized blend was dried at 100C. for 8 hours in desiccant air with a dew point S-29C. and ~ injéction molded on a Boy 22S injection molding machine - using:~ a melt temperature of 295C. and a mold temporature of 23C. to provide amorphous test ~ specimens. The impact properties of the blend are -h~ summàr:ized~in Table I.
2~0 The~ PCT of Example l was dried at 150C. for 16 hours in desiccant air with a dew point S-29C.
Ionomer B was dried at 60C. for 16 hours in desiccant air~with a dew point S-29C. The PCT and Ionomer B were pellet~bl-nded in a polyethylene bag suc~ that the concentration of Ionomer B was 20 weight percent. The ~- PCT~Ionomer B blend was placed in the hopper, under dry N2, of a Werner and Pfleiderer ZSK-28mm corotating, . 30 intermeshing twin screw extruder havîng the "hard" screw ~ design. The blend was melt processed at 295C. under ; high shear conditions, stranded and pelletized.
The pelletized blend was dried at 100C. for 8 hours in desiccant air with a dew point s-2SC. and in~ection molded on a Boy 22S injection molding machine `:

~094/06~63 PCT/US93/07868 ~' Xlll2~

using a melt t~mperature of 295C. and a mold temperature of 23OC. to provide amorphous test ~
specimens. The impact properties of the blend are summarized in Table I.

The PCT of Example 1 was dried at 150C. for 16 hours in desiccant air with a dew point <-29C.
Ionomer B was dried at 60~C. for 16 hours in desiccant air with a dew point S-29C. The PCT and Ionomer B were pellet blended in a polyethylene bag such that the concentration of Ionomer B was 30 weight percent. The PCT~Iono~er B blend was placed in the hopper, under dry N2, of a Werner and Pfleiderer ZSK-28mm corotating, 15~ intermeshing twin screw extruder ha~ing the "hard" screw desi~n.~ The blend was melt processed at 295C. under high~shear~conditions, stranded and pelIetized.
The pelletized blend~was dried at 100C. for 8 hours~in desiccant air with a dew point s-29C. and ~- 20 injection molded on a Boy 22S injection molding machine ;
using a melt temperature of 295C. and a mold `
temperature of 23-C. to provide amorphous test specimens. The impact properties of the blend are sunmarized in Tabie I.

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~ 094~06863 PCT/US93/0786~
1, TABLE I

IONOMER IONOMER IZOD IMPACT STRENGTH (J~m) A B Notched Unnotched Notched Unnotched EXAMPLE (wt%) fwt%)~23C. ~ r23C.) ~-40C.) (-40OC.) Ex. 1 0 0 13.9 950 14.4 748 (5CB) (3CB,2NB) (5CB) (5CB) -~
Ex. 2 20 0 529 1207 20.3 1714 (2CB,3NB) (lCB,3NB) (5CB) (2CB,3NB) Ex. 3 0 20 5g 988 36.8 491 (5CB) (3CB,2NB~ (SCB) t5CB) Ex. 4 0 30 587 1372 64 1239 (2CB,3NB) (5NB) (5CB) (2CB,3NB) ' ~ The results in Table I indicate that PCT~Ionomer A
and~PCT~lonomer B blends wherein the acid component is neutralized~with zino or sodium exhibit significant increases~in impact strength at 23OC. and -40C. over thê PCT control sample. The data also indicates that PCT~Ionomer~A blends~are more effective at lower ionomer concentrations of increasing the impact strength than PCT~Ionomer B blends. Thus, ionomers neutralized with zinc~are preferred. The~mode of impact failure for the blends was ducti}e~as opposed to brittle for the PCT
~; 30 control.

A polyester consisting of 100 mole percent terepht~alic acid,~34 mole percent ethylene glycol and 66 mole percent 1,4-cyclohexanedimethanol with an I.V.
of 0.75 was dried at 150C. for 16 hours in desiccant air with a dew point S-29C. The PCTG was placed in the hopper, under dry N2, of a Werner and Pfleiderer ZSK-28mm corotating, intermeshing twin screw extruder having th- "hard" screw design. The PCIG was melt processed at :' : :.

~ /06863 PCT/~S93/0786X
21~8~9 ::

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2750c. under high shear conditions stranded and pelletized~ The I.V. of the PCTG was 0.61.
The pelletized PCTG was dried at 100C. for 8 hours ;~.
in desiccant air with a dew point S-29C. and injection s molded on a Boy 22S injection molding machine using a ~;
melt temperature of 275C. and a mold temperature of ~
23C. to provide an amorphous test specimen. The I.V. `;
of the PCTG after molding was 0-55. The impact properties of the PCTG is summarized in Table II.
''' The PCTG of Example 5 was dried at 150C. for 16 ~.
hours in desiccant air with a dew point S-29C.
- Ionomer A was dried at 60OC. for 16 hours in desiccant air with a dew point S-29C. The PCTG and Ionomer A
were pellet blended in:a polyethylene bag such that the :-concentration of Ionomer A was 10 to 30 weight percent.
.
The~PCTG~Ionomer A:blend was melt blended and molded as in Example 5. The weight percents of Ionomer A used in 20:~ ~èach:example and impact properties of the PCTG~Ionomer A
blends are summarized in Table II. ;~

EXAMPLES 9-11 .
The:PCTG of Example 5 was dried at 150C. for 16 :.
: 25 hours in desiccant air with a dew point S-29C.
. Ionomer B was dried at 60C. for 16 hours in desiccant ~:
air with a dew point <-29C. The PCTG and Ionomer B
were pellet blended in a polyethylene bag such that the concentration of Ionomer B was 10 to 30~weigbit perceht.
:30 The PCTG~Ionomer a blend was melt blended and molded as in Example 5. The weight percents of Ionomer B used in each example and impact properties of the PCTG~Ionomer B
- b}ends are summarized in Table II.

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. TABLE II
IONOMER IZQD IMPACT STRENGTH (J~m~ -AB Notched Unnotched Notched Unnotched EXAMPLE (wt%) . (wt%? r23c.)( 23C.) r--40~L (_40OC.) . Ex. S 0 0 11162147 42.7 2019 (lCB,3NB) ~5NB) (SCB) (lCB,3NB) Ex. 6 10 0 12661682 758 1634 ~:
(SNB)(5NB) ~3CB,2NB) (5NB) ;~
~x. 7 20 0 10411639 1244 1522 :.
(5NB)(5NB) (5NB) ~ (5NB) lS Ex. 8 30 a 1079 1~15 1196 1570 (5NB) (5NB) (5NB) (5NB) :
Ex. 9 0 10 1196 1752 139 1618 :~
(5NB) (5NB) (SCB) (5NB) Ex. 10 - 0 20 1031 1527 150 1671 -: (4NB) : (5NB) (5CB) (5NB) -Ex.~l:1 0 30 1041 1436 1169 1701 25~ (SNB) (5NB) (SNB) t5NB) - .
: The results in Table II indicate that a polyester consisting of 100~mole:percent terephthalic acid, 34 :~
~mole~percent ethylene glycol and 66 mole percent 4-cyclohexanedimethanol blended with Ionomer A and Ionomer B, wherein the ionomer is present~in as little : . as~l0 weight percent, exhibit significant increases in ~:
notched;impact strength at -40OC. over the PCTG control sample. The data also indicates that PCTG~Ionomer A
:~ blends are more effective at lower ionomer ~`. c~nqentrations of!increasing the impactl~strength than PCTG~Ionomer B blends. Thus, ionomers neutralized with zino are preferred. The mode of impact failure at ,~
-40C. for the blends was ductile as opposed to brittle ~: for the P~TG control.
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~ '' ' W09~/06863 PCT/US93/07868 2112~4~

A polyester consisting of loo mol~ percent ~
terephthalic acid, 69 mole percent ethylene glycol and 31 mole percent 1,4-cyclohexanedimethanol with an I.V. ~`
of 0.75 was dried at 150C. for 16 hours in desiccant ~-air with a dew point <-29C. The PETG was placed in the hopper, under dry N2, of a Werner and Pfleiderer ZSK-28mm corotating, intermeshinq twin screw extruder having `
the "hard" screw deæign. The PETG was melt processed at lo 260C. under high shear conditions, stranded and pelletized. The I.V. of the PETG was 0.61.
- The pelletized PETG was dried at 100C. for 8 hours in desiccant air with a dew point S-29C. and injection molded on a Boy 22S injection molding machine using a melt temperature of 260C. and a mold temperature of 23C. to provide an amorphous test specimen. The I.V.
of the PETG after molding was 0.55. The impact -~
properties of~ the PETG are summarized in Table III.

-EXAMP~ES 13-14 The PETG of Example 12 was dried at 150C. for 16 -hours in desiccant air with a dew point S-29C.
Ionomer A was dried at 60C. for 16 hours in desiccant air with a dew point S-29C. The PETG and Ionomer A
were pellet blended in a polyethylene bag such that the concentration of Ionomer A was 10 and 20 weight percent.
The PETG~Ionomer A blend was melt blended and molded as in Example 12. The weight percents of Ionomer A used in each iexamplé and imp~ct properties of t4e PET¢~Ion~mer~A
blonds are ummarized in Table III. `~
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The PETG of Examp}e 12 was dried at 150C. for.16 hours in desiccant air with a dew point S-29C.
Ionomer B was dried at 60C. for 16 hours in desiccant :::

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~094/06~63 PCT/US93/07868 - 22 - ;

air with a dew point <-29C. The PETG and Ionomer 8 were pellet blended in a polyethylene bag such t-hat the concentration of Ionomer B was 10 and 20 weight percent.
The PETG~Ionomer B blend was melt blended and molded as .
in Example 12. The weight percents of Ionomer B used in each example and impact properties of the PETG~Ionomer B
blends are summarized in Table III. :

TABLE III
10 IONOMER -IZOD IMPACT STRENGTH (J~m) :.
A B Notched Unnotched Notched Unnotched :
: EXAMPLE (wt%) (wt%) ~23C.~ ~23C.) (-40~C.) ~=40C.) Ex. 12 0 0 53 2152 53 ~789 .(5~B) (5NB) (SCB) (2CB~,3NB) Ex. 1310 0 1244 1613 75 1517 (5NB) (lCB,4NB) (5CB) (2CB,3NB) -Ex. 1420 0 1234 1586 150 1629 : (5NB) (5NB) (5CB) (5NB) ,:
Ex. 15 0 10 139 1858 69 1933 (5CB) (5NB) (SCB) (5NB) -~
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Ex. 16 0 20 961 1671 69 1784 -~ (4NB) (5NB) (5CB) (5NB) The results in Table III indicate that the addition of 10 weight percent zinc ionomer, Ionomer A, to the ~ PETG polyester consisting of 100 mole percent ;- ~ terephthalic acid, 69 mole percent ethylene glycol and ~- 31 mole percent 1,4-cyclohexanedimethanol results in a ~ignificant increase in notched Izod impact strength at 23C. from 53 J ~ with complete break tO 1244 J~m With`~
no break. The addition of 20 weight percent sodium -ionomer, Ionomer B, results in a sîmilar increase in : notched Izod impact strength at 23C. Low temperature : 40 impact values are also increased with the blends, ~.:

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U'094/06863 PCT/~S93/07~68 ~' 21'~ 9 `~

especially with the PETG/Ionomer A blend at 20 weight .
percent, as compared to the PETG control.
Many variations will suggest themselves to those skilled in this art in light of the above detailed description. All such obvious modifications are within the full intended scope of the appended claims.

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Claims (8)

WHAT IS CLAIMED IS:

1. A process for preparing a poly(1,4-cyclohexylenedimethylene terephthalate)/ionomer blend which exhibits high impact strength comprising:
(I) melt blending (A) 70 to 90 weight percent of a polyester which comprises (1) a dicarboxylic acid component consisting essentially of repeat units from terephthalic acid, and (2) a diol component consisting essentially of repeat units from about 15 to 100 mole percent 1,4-cyclohexanedimethanol and from 0 to about 85 mole percent ethylene glycol, based on 100 mole percent dicarboxylic acid and 100 mole percent diol, said polyester having an inherent viscosity of about 0.4 to about 1.5 dl/g; and (B) 30.0 to 10.0 weight percent of an ionomer comprising repeat units from 80 to 95 weight percent of ethylene and 5 to 20 weight percent of an unsaturated carboxylic acid selected from the group consisting of acrylic acid and methacrylic acid, and the carboxylic acid groups being neutralized to the extent of about 40 to about 95 percent with zinc or sodium ions; wherein the combined weights of (A) and (B) total 100 percent and the blending is conducted in an extruder containing at least eight kneading blocks wherein at least two of the kneading blocks are left-handed, at a shear rate of 3500 sec-1 to 7000 sec-1; and (II) forming the blend into an article.

2. A process for preparing a poly(1,4-cyclohexylenedimethylene terephthalate)/ionomer blend which exhibits high impact strength comprising:
(I) melt blending (A) 70 to 90 weight percent of a polyester which comprises (1) a dicarboxylic acid component consisting essentially of repeat units from terephthalic acid, and (2) a diol component consisting essentially of repeat units from about 15 to 100 mole percent 1,4-cyclohexanedimethanol and from 0 to about 85 mole percent ethylene glycol, based on 100 mole percent dicarboxylic acid and 100 mole percent diol, said polyester having an inherent viscosity of about 0.4 to about 1.5 dl/g; and (B) 30.0 to 10.0 weight percent of an ionomer comprising repeat units from 80 to 95 weight percent of ethylene, 5 to 15 weight percent of an unsaturated carboxylic acid selected from the group consisting of acrylic acid and methacrylic acid, the carboxylic acid groups are neutralized to the extent of about 40 to about 95 percent with zinc ions, and 5 to 15 weight percent of an alkyl acrylate or methacrylate having 1 to 8 carbon atoms in the alkyl group, wherein the combined weights of (A) and (B) total 100 percent and the blending is conducted in an extruder containing at least eight kneading blocks wherein at least two of the kneading blocks are left-handed, at a shear rate of 3500 sec-1 to 7000 sec-1; and (II) forming the blend into an article.

3. The process according to Claim 1 wherein the polyester, component (A), is poly(1,4-cyclohexylenedimethylene terephthalate).

4. The process according to Claim 1 wherein the poly(1,4-cyclohexylenedimethylene terephthalate) has an inherent viscosity of 0.5 to 0.9.

5. The process according to Claim 1 wherein the ionomer, component (B), has a melt index at 190°C. of 0.5 to 5.0 grams.

6. The process according to Claim 5 wherein the ionomer, component (B), has a melt index at 190°C. of 1.0 to 2.0 grams.

7. The process according to Claim 1 wherein the ionomer, component (B), comprises discrete particles, the major portion of which have diameters of 0.1 to 0.3 microns.

8. The process according to Claim 1 wherein the blending is conducted in an extruder capable of providing a shear rate of 3500 sec-1 to 6000 sec-1.