KR100697494B1 - Reactor grade copolyesters for shrink film applications - Google Patents

Abstract

Reactor grade copolyester compositions, as well as heat shrinkable films made therefrom, have unexpectedly higher ductility than multicomponent blends of copolyesters having the same monomer content. The reactor grade copolyester composition comprises at least about 90 mole percent diacid component, and (a) about 72 to about 88 mole percent ethylene glycol, about 10 to about 15 mole percent 1,4-cyclohexanedimethanol and about 2 to about 13 mole percent diethylene glycol, or (b) about 59 to about 77.5 mole percent ethylene glycol, about 15 to about 28 mole percent 1,4-cyclohexanedimethanol and about 7.5 to about 13 mole percent It is prepared from the diol component of diethylene glycol. In addition, heat shrinkable films can be made to closely match the shrinkage properties of polyvinyl chloride by varying the amount of diol component of the reactor grade copolyester composition. In addition, the reactor grade copolyester composition has a b ^* color value of -1.0 to less than 4.5, wherein the diacid component is at least about 90 mole percent terephthalic acid and the diol component is from about 52 to about 88 mole percent ethylene glycol, about 10 To about 28 mole% 1,4-cyclohexanedimethanol and about 2 to about 20 mole% diethylene glycol.

Description

Reactor Grade Copolyester for Shrink Films {REACTOR GRADE COPOLYESTERS FOR SHRINK FILM APPLICATIONS}             

Reference to related application

This application claims priority based on US Provisional Application No. 60 / 149,298, filed August 17, 1999.

The present invention relates to reactor grade copolyester compositions useful as materials for making heat shrinkable plastic films, and more specifically heat shrinkable plastic films.

Heat shrinkable plastic films are used as coatings that hold objects together and as outer packaging for bottles, cans and other containers. For example, such films are used to cover the cap, neck, shoulder or middle portion of a bottle, or the entire bottle; It is used to label, protect, package, or increase the value of a product. In addition, such films may be used as a coating for packing objects such as boxes, bottles, plates, rods or notes together in groups, and such films may also be firmly attached as packaging materials. The above uses have advantages in terms of shrinkage and internal shrinkage stress of the film.

Poly (vinyl chloride) (PVC) films are leading the shrink film market. However, polyester films were considered an important alternative because they do not have the environmental problems associated with PVC films. Polyester shrink films ideally have properties very similar to PVC films so that polyester can act as a "drop-in" substitute on existing shrink tunnel devices. PVC film properties suitable for replication include: (1) relatively low shrinkage onset temperature, (2) total shrinkage gradually increasing in a controlled manner as the temperature increases, (3) low shrinkage to prevent the lower container from crushing, (4 A) high overall shrinkage (eg, 50% or greater) and (5) inherent film strength to prevent unnecessary tearing and tearing of the film before and after shrinkage.

In US Pat. No. 5,859,116 (hereinafter '116 patent), the heat shrinkable polyester film comprises 1 to 98.5% by weight of 1,4-cyclohexanedimethanol modified poly (ethylene terephthalate) (PETG copolyester), 15 98.5 to 1 wt% diethylene glycol modified poly (ethylene terephthalate) (DEG modified PET copolyester) with a b ^* value of less than 0.5 to 3 wt%, and optionally 5 to 15 wt% It is prepared from a copolyester blend of% crystalline polyester, for example poly (ethylene terephthalate) (PET). PETG copolyesters comprise at least 95 mole percent of the dicarboxylic acid component of terephthalic acid (TA), and 65 to 80 mole percent of ethylene glycol (EG) and 35 to 20 mole percent of 1,4-cyclohexanedimethanol (CHDM) Have components. DEG modified PET copolyesters have at least 75 mol% of the dicarboxylic acid component of terephthalic acid (TA) and 10 to 50 mol% of diethylene glycol (DEG) and 50 to 90 mol% of ethylene glycol. By varying the diethylene glycol content in such copolyester blends, heat shrinkable films made from them can be made to have desired shrinkage properties, such as low-start temperatures similar to polyvinyl chloride (PVC). Using a DEG modified PET copolyester with improved transparency, a haze-free shrink film with a b ^* color value of 0.9 to 1.10 is produced.

While the shrink film of the '116 patent offers many advantages in the prior art, some significant drawbacks are associated with the use of these copolyester blends. The blend formulation may include up to four components including PETG copolyester, DEG modified PET copolyester, PET and antiblocking agents. Multicomponent blends take each different component, making the process more complex and labor intensive during the manufacturing process of drying, weighing, blending and extruding. For example, PETG copolyester should be dried at 150 ° F, PET at 300 ° F, and DEG modified copolyester at 110 ° F. Thus, three dryers are needed to make the blend. In addition, since changes in composition affect the properties, accurate blending of all materials is important for controlling the quality of the film. Blending of amorphous polymers such as PETG copolyester and DEG modified PET copolyesters and crystalline polymers such as PET can also cause problems during extrusion, since the materials have different melting properties. In the case of melting, mismatching can cause uneven mixing during extrusion. In addition, blending, material separation, inventory and storage of numerous materials can be excessive.

Accordingly, there is a need in the art for a polyester material that can be used as a material for shrink films to remove excessive handling, dry more efficiently, and produce products more consistently. Therefore, the present invention relates primarily to providing such a material.

Summary of the Invention

The reactor grade copolyester composition is a blend blend of PETG copolyester and DEG modified PET copolyester, both of which have the same mole percent monomer, as disclosed in US Pat. No. 5,859,116 (hereinafter '116 patent). In comparison, it has unexpectedly high ductility. Reactor grade copolyester compositions and shrink films made therefrom comprise a diol component comprising a diol component, one of two compositions, and a residue of at least about 90 mole percent terephthalic acid. Diol component (a) comprises a residue of about 72 to about 88 mol% ethylene glycol, about 10 to about 15 mol% 1,4-cyclohexanedimethanol and about 2 to about 13 mol% diethylene glycol . Diol component (b) comprises a residue of about 59 to about 77.5 mol% ethylene glycol, about 15 to about 28 mol% 1,4-cyclohexanedimethanol and about 7.5 to about 13 mol% diethylene glycol . The diacid component and diol component are each based on 100 mol%.

In another embodiment, the heat shrinkable film made from the reactor grade copolyester composition has a shrinkage curve that is nearly similar to that of the PVC film. The discrete component of the reactor grade copolyester composition comprises at least about 90 mole percent residue of terephthalic acid. The diol component of the reactor grade copolyester composition is within the range of 61 to about 82 mole% ethylene glycol, about 16 to about 26 mole% 1,4-cyclohexanedimethanol, and the ± 2.5 mole% of From about 2 to about 13 mole% of diethylene glycol residues:

In another embodiment, the reactor grade copolyester composition comprises a diacid component comprising a residue of at least about 90 mole percent terephthalic acid, based on 100 mole percent diacid component and 100 mole percent diol component, respectively, and from about 52 to about 88 Diol component comprising a residue of mol% ethylene glycol, about 10 to about 28 mol% 1,4-cyclohexanedimethanol and about 2 to about 20 mol% diethylene glycol. Co-polyester composition, and has a '116 patent under the blend formulation of the b ^* color value of -1.0 to 4.5 in significantly improved unexpectedly compared to the b ^* color value.

1 is a graph showing the change in percent shrinkage of a 3 mil (75 micron) film of a reactor grade copolyester composition of the present invention with varying amounts of 1,4-cyclohexanedimethanol, diethylene glycol and ethylene glycol to be.

FIG. 2 is a graph showing the percent shrinkage (%) curve of a 2 mil (50 micron) film of the reactor grade copolyester composition of the present invention as compared to prior art polymers.

3 is a graph showing elongation at break in the non-stretch direction as a function of composition for the reactor grade copolyester composition of the present invention.

4 is a graph showing elongation at break in the non-stretching direction as a function of composition for the blend formulation of the '116 patent.

FIG. 5 is a graph showing the percent free shrinkage after 30 seconds as a function of temperature for the reactor grade copolyester compositions of the present invention compared to polymers of the prior art.

FIG. 6 shows the dividing line of the sum of squares of shrinkage errors for reactor grade copolyester compositions of the present invention compared to PVC shrink curves.

The present invention relates to reactor grade copolyester compositions and heat shrinkable films prepared therefrom. The term "reactor grade" means a product made directly from esterification / transesterification of certain diacid / diester monomers and diol monomers, and subsequent polycondensation. The preparation of reactor grade copolyester compositions is in contrast to the preparation of copolyester blend formulations which physically blends more than one polyester or copolyester composition in an extruder to yield the desired material. Reactor grade copolyester compositions (herein referred to as "rxn-copolyesters") are compared to the '116 patent's multicomponent copolyester blend formulations (hereinafter referred to as "' 116 patent blends") (Both have the same final copolyester composition), as a single-component material for use in the manufacture of conventional films and shrink films, has unexpectedly superior properties and other advantages.

In one embodiment of the present invention, the rxn-copolyester is unexpectedly softer than the copolyesters prepared from blends of the '116 patent (with the same monomer content). Thus, films made from rxn-copolyester are less tearing than films made with blends of the '116 patent during printing and web processing. As shown in Examples 3 to 5 and FIGS. 3 and 4, the change from ductility to brittleness of the oriented film of rxn-copolyester and the oriented film of the blend of '116 patent increases with the value of DEG. Brittleness is undesirable because it causes tearing of the film in an unoriented direction. The soft-brittle change for the rxn-copolyester occurs at higher DEG values (about 13 mol%) compared to the blend of the '116 patent (about 7.5 mol%). Thus, rxn-copolyesters can incorporate more DEG without loss of ductility, making them more flexible in modifying the shrinkage window of rxn-copolyesters. The rxn-copolyester may comprise a diacid component comprising a residue of at least about 90 mole percent terephthalic acid; And (a) about 72 to about 88 mole percent ethylene glycol, about 10 to about 15 mole percent 1,4-cyclohexanedimethanol and about 2 to about 13 mole percent diethylene glycol, and (b) about 59 To about 77.5 mole% ethylene glycol, about 15 to about 28 mole% 1,4-cyclohexanedimethanol and about 7.5 to about 13 mole% diethylene glycol. The diacid component and diol component are each based on 100 mol%. As a measure of ductility, rxn-copolyester has an elongation at break in the non-stretch direction of at least about 300%, preferably at least about 400%, as measured according to ASTM D882 for a film of nominal 2 mil (50 micron) thickness. Has

In addition, as shown in Examples 2 and 6 and FIGS. 2, 5 and 6, the shrinkage of films made from rxn-copolyesters preferably matches the shrinkage of PVC films. In this preferred embodiment, the diol component (b) of the rxn-copolyester comprises 16 to 26 mole% 1,4-cyclohexanedimethanol. More preferably, with respect to the preferred mole% of 1,4-cyclohexanedimethanol, the residue of diethylene glycol is present in the range of ± 2.5 mole% according to the following equation:

Equation 1

In another embodiment of the invention, the heat shrinkable film comprises a diacid component comprising at least about 90 mole percent residue of terephthalic acid, and about 61 to about 82 mole percent ethylene glycol, about 16 to about 26 mole percent 1,4 Rxn-copolyesters comprising cyclohexanedimethanol and a diol component comprising a residue of from about 2 to about 13 mol% of diethylene glycol within the range of ± 2.5 mol% of the following formula:

Equation 1

This embodiment of the invention provides a heat shrinkable film having a shrink curve that is nearly similar to a PVC film. Preferably, the heat shrinkable film has a high ductility compared to the heat shrinkable film of the blend of the '116 patent. The diol component of such heat shrinkable films comprises about 7.5 to about 13 mole percent residues of diethylene glycol.

2 and 6, EASTAR PETG copolyester 6763, inventive rxn-copolyester, blend of '116 patent and PVC were compared. Of course, each of these materials can be used as a shrink film. For most applications, low shrinkage onset temperatures are desirable in preventing damage from occurring regardless of the object being packaged. In addition, although a certain degree of shrinkage is required depending on the packaging, typically the minimum is 50% in the frame direction, ie around the packaging. rxn-copolyester is a much improved shrink polymer compared to EASTAR PETG copolyester 6763 in that (a) reduces the onset temperature, shrinkage at 90 ° C. and shrinkage rate (the slope of the shrinkage curve), and (b ) PVC is a much improved shrinkage polymer compared to the '116 patent blend in that it reduces the complexity of the manufacturing process and broadens the ductility of the shrink film, and (c) eliminates environmental problems and provides equivalent materials. It can be seen from the above results that the result is a much improved shrinkage polymer compared to the All these improvements contribute to the user-friendliness of shrink films made from rxn-copolyesters in shrink tunnels. Low shrinkage rates will prevent wrinkles or bubble formation in the shrinking tunnel. Thus, the finishing of the label will be greatly improved. In addition, the rxn-copolyester can control maintaining shrinkage at high temperatures, which is important for labeling the entire contour of a bottle with a wide body and narrow neck. The shrinkage of the PVC film is below the level below 90 ° C, preventing the label from tightly covering the narrow neck of the bottle contour.

In another embodiment of the present invention, the rxn-copolyester is a diacid component comprising at least about 90 mole percent residue of terephthalic acid (TA), and about 52 to about 88 mole percent ethylene glycol (EG), about 10 to Diol components comprising about 28 mole% 1,4-cyclohexanedimethanol (CHDM) and about 2 to about 20 mole% diethylene glycol (DEG) residue. The mol% is based on 100 mol% of a diacid component and 100 mol% of a diol component. The rxn-copolyester has a b ^* color value of -1.0 to less than 4.5. Preferred b ^* color values are -1.0 to 3.5.

rxn-copolyesters comprise DEG, and typically copolyesters containing DEG will have a higher b ^* color value compared to copolyesters that do not include DEG. For example, EASTAR PETG copolyester 6763 without DEG and EASTOBOND copolyester 19411 with DEG have a b ^* color value of about 4.5 and 9.5, respectively. Both materials are available from Eastman Chemical Company, Kingsport, Tenn., USA, and used in blend examples of the '116 patent. Blends of the '116 patent have a b ^* color value of greater than 4.5. Thus, the b ^* color value of the present invention is unexpected when compared to blends of the '116 patent and single component copolyesters having the same DEG content.

The improved transparency measured by the low b ^* color value depends on the process for the preparation of the rxn-copolyester, which method comprises a catalyst of 10 to 100 ppm titanium, 0 to 75 ppm manganese, and 25 to 150 ppm phosphorus System, and an organic toner system of substituted 1,4-bis (2,6-diallylanilino) anthraquinone which is 1.0 to 10.0 ppm of a red compound anthraquinone and 1.0 to 10.0 ppm of a blue compound. do. Preferably, the catalyst system comprises 15 to 50 ppm titanium, 20 to 60 ppm manganese, 30 to 70 ppm phosphorus, and the organic toner system is 1.0 to 5.0 ppm red compound anthraquinone and 1.0 to 5.0 ppm Substituted 1,4-bis (2,6-diallylanilino) anthraquinone which is a blue compound. Combinations of red and blue compounds as organic toners are disclosed in US Pat. Nos. 5,372,864 and 5,384,377, which are incorporated herein by reference.

Titanium is preferably added as titanium tetraalkoxide, for example titanium tetraisopropoxide, titanium tetraethoxide or titanium tetrabutoxide. Manganese is preferably used as a salt. Examples of suitable manganese salts are manganese benzoate tetrahydrate, manganese oxide, manganese acetate, manganese acetylacetonate, manganese succinate, manganese glycolate, manganese naphthalate and manganese salicylic salicylate. Phosphorus is preferably added as a phosphate ester, for example trialkyl phosphate and triphenyl phosphate, or phosphoric acid.                 

In all of the above embodiments of the invention, the following general description applies to rxn-copolyesters and films made therefrom. The use of corresponding acid anhydrides, esters, and acid chlorides of diacids is also encompassed by the term “diacids”. In the case of monomers present in the isomeric form, for example cis-1,4-cyclohexanedimethanol and trans-1,4-cyclohexanedimethanol, isomers are also included in the use of any general expression of the monomers.

The diacid component in the rxn-copolyester preferably comprises at least 95 mol%, more preferably 100 mol% of terephthalic acid. The diacid component may be modified by other diacids in an amount up to 10 mol%. Suitably modified diacids include saturated aliphatic dicarboxylic acids having 4 to 12 carbon atoms and alicyclic dicarboxylic acids having 8 to 12 carbon atoms. Specific examples of the dicarboxylic acid include phthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, cyclohexanediacetic acid, diphenyl-4,4'-dicarboxylic acid, succinic acid and glutaric acid. , Adipic acid, azelaic acid and sebacic acid.

The diol component of the rxn-copolyester may optionally be modified with up to 10 mole percent of one or more different diols. Such additional diols include alicyclic diols having 6 to 15 carbon atoms and aliphatic diols having 3 to 8 carbon atoms. Examples of such diols include triethylene glycol, propane-1,3-diol, butane-1,4-diol, 2,2-dimethylpropane-1,3-diol (neopentyl glycol), pentane-1,5-diol , Hexane-1,6-diol, 3-methylpentanediol- (2,4), 2-methylpentanediol- (1,4), 2,2,4-trimethylpentanediol- (1,3), 2 -Ethylhexanediol- (1,3), 2,2-diethylpropanediol- (1,3), hexanediol- (1,3), 1,4-di- (hydroxyethoxy) -benzene, 2,2-bis- (4-hydroxycyclohexyl) -propane, 2,4-dihydroxy-1,1,3,3-tetramethyl-cyclobutane, 2,2-bis- (3-hydroxy Ethoxyphenyl) -propane, 2,2-bis- (4-hydroxypropoxyphenyl) -propane and the like.

In addition, rxn-copolyesters contain small amounts of trifunctional or tetrafunctional comonomers such as trimellitic anhydride, trimethylolpropane, pyromellitic dianhydride, pentaerythritol and other polyesters generally known in the art. It may contain a forming polyacid or polyol.

The rxn-copolyester is 0.4 to 1.5 dL / g, preferably 0.6 to 0.9 dL as measured at 25 ° C. using 0.50 g of polymer per 100 ml of solvent consisting of 60 wt% phenol and 40 wt% tetrachloroethane. / g has an intrinsic viscosity (IV).

rxn-copolyesters can be prepared by conventional polycondensation procedures well known in the art. This process involves the direct condensation of diacids using diols or by transesterification using dialkyl dicarboxylates. For example, dialkyl terephthalates, such as dimethyl terephthalate, are transesterified with diols at elevated temperatures in the presence of a catalyst.

The rxn-copolyester is formed into a film by well known extrusion methods. The pellets of rxn-copolyester are placed in an extruder for melting and the melted rxn-copolyester is formed into a film as it exits the extruder. The form of the film is not limited in any way. For example, it may be a flat sheet or tube. The obtained film can be stretched in a constant direction by, for example, 2 to 6 times the initial measurement. Optionally, the rxn-copolyester can be formed into a film by calendering, as disclosed in US Pat. No. 6,068,910 to Flynn et al. Of course, other conventional film forming methods can also be used.

Stretching of the film may be carried out by any conventional method, for example, a roll stretching method, a long-gap stretching method, a tenter-drawing method, and a tubular stretching method. Using these arbitrary methods, it can carry out biaxial stretching continuously, biaxial stretching simultaneously, uniaxial stretching, or a combination thereof. By the biaxial stretching method mentioned above, it can extend | stretch simultaneously in a machine direction and a lateral direction. Furthermore, it can be stretched once in one direction and then in the other direction to obtain effective biaxial stretching. Preferably, the stretching of the film is such that the average glass transition temperature (T _g ) to T _g +5 ° C to T _g +80 ° C, preferably T _g +10 ° C to T _g +20 ° C, of the rxn-copolyester composition. By preheating the film at a temperature in the range. Preferably, the draw speed is 5 to 20 inches (12.7 to 50.8 cm) per second. The draw ratio is defined as the draw ratio in the x-axis direction to the draw ratio in the y-axis direction. The draw ratio is the final length of the film divided by the initial length of the film.

Accordingly, the present invention provides reactor grade copolyester compositions and their preparation having superior performance properties, in particular high ductility to reduce tears, and a more consistent shrinkage curve for competitive PVC shrink films compared to the '116 patented blends. The finished film. In addition, in contrast to the multi-component blend of the '116 patent, the single component material, rxn-copolyester, is characterized by removing excess material treatment, increasing drying efficiency and improving batch-to-batch consistency, Reduced raw materials and costs in the production of shrinkable films.

The present invention may be further illustrated by the examples of the preferred embodiments below, but unless otherwise indicated, these examples are for illustrative purposes only and will be understood not to limit the scope of the invention. .

Example 1: Composition of rxn-copolyester

To determine the effect on shrinkage, rxn-copolyesters were prepared with varying mole percentages of DEG and CHDM. The preparation of these resins followed standard manufacturing methods for the preparation of polyesters, which are already well known in the art. The rxn-copolyester composition is as described in Table 1 below.

As shown in FIG. 1, the composition of the rxn-copolyester is adjusted to have a shrink film whose properties change. Different curves show percent shrinkage of rxn-copolyesters with different compositions. The percent shrinkage at 90 ° C. of the 3 mil (75 micron) film decreases with decreasing CHDM. Shrink onset temperature decreases as DEG increases.

Reference number TA CHDM DEG EG 11 100 31 0 69 15 100 27 5 68 14 100 23 7 70 13 100 22 8 70 12 100 20 9 71

Example 2: Property Comparison

In this Example 2, rxn-copolyester was prepared to be similar to the multicomponent blend blend of 80 mol% PETG copolyester and 20 mol% DEG modified PET. The 80/20 blend contains EASTAR PETG copolyester 6763, an amorphous copolyester containing very low amounts of DEG (about 2 mol%) and 31 mol% CHDM, and EASTOBOND, including 37 mol% DEG without CHDM. Prepared using copolyester 19411. Both materials are commercially available from Eastman Chemical Company, Kingsport, Tennessee, USA. Thus, both the rxn-copolyester and 80/20 blend were residues of 100 mol% terephthalic acid, 25 mol% 1,4-cyclohexanedimethanol, 7 mol% diethylene glycol and 68 mol% ethylene glycol It includes.

The performance characteristics of the rxn-copolyester and 80/20 blends were expected to be substantially similar because the final film composition is the same. However, this case was different from the case shown in Table 2 and FIG. 2. For example, the glass transition temperature (T _g ) of the rxn-copolyester was 77 ° C compared to 73 ° C of the 80/20 blend and was 4 ° C lower than the PETG copolyester. Compared to the 80/20 blend, the shrinkage onset temperature of the rxn-copolyester (temperature at about 5% shrinkage) also had a similar trend. The shrinkage at 90 ° C. of the rxn-copolyester is 10% lower than that of the PETG copolyester and is about the same as the 80/20 blend.

Reference number matter T _g (℃) Start temperature (℃) % Shrinkage at 90 ℃ 21 PETG Copolyester 81 69 71 22 Rxn-Copolyester 77 65 59 23 80/20 blend 73 63 61 24 PVC 70 60 56

Example 3: Optimal Composition of rxn-Copolyester

rxn-copolyesters were prepared with varying mole percent of DEG and CHDM in order to determine the optimum composition. These blends are shown in Table 3 below. The desired intrinsic viscosity (IV) of the resin was about 0.76 dL / g as measured at 25 ° C. using 0.50 g of polymer per 100 ml of solvent consisting of 60 wt% phenol and 40 wt% tetrachloroethane. The preparation of these resins has followed standard preparation methods for the preparation of polyesters which are already well known in the art.

A portion of these resins were dried and dried at 500 ° F. (260 ° C.) on a 1.5 ”(3.8 cm) Killion extruder or a 2.5” (6.4 cm) Davies standard extruder with a thickness of 9 mils (0.23 mm). Extruded into a film at nominal temperature. Then, part of the film was tee off. M. The T. M. Long film stretcher was used to draw at about 4 × 1 draw ratio at 195 ° F. (90 ° C.). Another portion of the resin was run on a commercial tenter line and drawn at approximately the same conditions.

Sample number DEG (%) CHDM (%) EOB (MD) (%) 1a 5.7 24 461 (± 24) 2a 4.8 17.4 466 (± 20) 3a 8.2 16.7 471.6 (± 12) 4a 7.5 23.8 469 (± 12) 5a 8.4 19.9 474 (± 19) 6a 21 31 3.3 (± 0.1) 7a 14 31 182 (± 51) 8a 9 31 370 (± 11) 9a 15 15 4.7 (± 4) 10a 25 15 66.3 (± 48) 11a 9 20 467 (± 21) 12a 2 31 446 (± 3)

Example 4: Blend Blend

For comparison, EASTAR PETG copolyester 6763, EASTOBOND copolyester 19411 and EASTAPAK PET polyester 7352 (poly (ethylene terephthalate)) were pellet-pellet blended to provide the same CHDM as in the rxn-copolyester of Table 3 above and Prepared to DEG value and extruded into film. These resins were blended in appropriate amounts to meet most of the compositions in Table 3 above. These are shown in Table 4 below. The rxn-copolyester of Example 3 was followed as it was except for differences in resin preparation, extrusion and stretching of the blend. Blends represent the prior art described in the '116 patent.

Blend Blend Sample number DEG (%) CHDM (%) EOB (MD) (%) 1b 5.7 24 381 (± 210) 2b 4.8 17.4 485 (± 16) 3b 8.2 16.7 3.7 (± 0.2) 4b 7.5 23.8 469 (± 11) 5b 8.4 19.9 178 (± 239) 6b 11 12 3.0 (± 0.2) 7b 6.5 21 387 (± 214) 8b 7 20 346 (± 219) 9b 8.5 12 4.2 (± 0.4) 10b 7 12 133 (± 279) 11b 5.5 12 54 (± 110) 12b 15 15 4.7 (± 3.8) 13b 9 20 241 (± 233)

Example 5: Comparison of Tensile Properties and Ductility

Tee the resin samples of Tables 3 and 4 above. M. Stretched to 4 × 1 at 195 ° F. (90 ° C.) using a long film drawer. The stretching conditions accurately simulated the orientation in commercial tenter frames. These stretched samples were extended in both stretch (TD) and non-stretch (MD) directions according to ASTM D882 guidelines. Elongation at break (EOB) in each direction was tested as a quantitative measure of the ductility of the film. Low values (about 5-10%) represent brittle films that can easily tear during processing. In contrast, high values (at least about 300%) refer to a film that is typically unbreakable and has sufficient ductility to withstand the processing and shrinkage around the container.

Comparison of EOB values at stretching (TD) shows no major difference between the blend and the rxn-copolyester, all values being between 50 and 80%. In contrast, the EOB in the weak non-stretching direction is generally high (greater than 400%), but the samples tend to show more brittleness (lower EOB) as the DEG values increase for the blend and the rxn-copolyester. . It is well known in the art that DEG can cause film brittleness. However, DEG is necessary to lower the shrinkage onset temperature.

Film brittleness is an important property in indicating tearing film properties and has been used to compare the properties of blends versus rxn-copolyesters. Unexpectedly, there was a difference in EOB between the blend and the rxn-copolyester. Comparing rxn-copolyester 3a and blend 3b (same composition), the blend had only about 3% EOB, while rxn-copolyester had 471% EOB. Similarly, comparing samples 5a and 5b shows that the EOB of the blend is much lower than rxn-copolyester (178% vs. 474%).

Analysis of the data clearly showed that there were separate optimal composition windows for the blend and rxn-copolyester, each remaining soft. To visualize these windows, composition maps for each of the rxn-copolyesters and blends were made in FIGS. 3 and 4. The map shows the mole% of DEG versus the mole% of CHDM for each composition. Square numbers at each operating point represent the EOB for the given composition. In FIG. 3, the change from the soft film to the brittle film does not begin until the DEG value exceeds about 13 mol%. CHDM is not seen as a major factor. In contrast to that shown in FIG. 4, this change to the blend occurred at about 7.5 mol%. In addition, the CHDM value should be greater than about 15 mole percent in the blend to prevent brittleness.

The following composition ranges are important for preferred embodiments of the present invention:                 

(1) if DEG is less than 7.5 mol% and CHDM is greater than 15 mol%, both the blend and the rxn-copolyester are soft;

(2) if the CHDM is less than 15 mol%, the DEG is less than 13 mol% or the DEG is greater than 7.5 mol% and less than 13 mol%, the blend is brittle but the rxn-copolyester is soft;

(3) The blend and the rxn-copolyester are both brittle if the DEG is greater than 13 mol%, regardless of the level of CHDM.

Thus, rxn-copolyesters are softer over a broader composition range. This is important because, as shown in Example 6, DEG in the range of 7.5 to 13 mole percent is in a window where most of the shrink curves closely match the PVC. This composition window may vary slightly due to changes during the process, but the blend is still expected to be brittle than the rxn-copolyester for any set process conditions.

Example 6: Comparison of Shrinkage Curves for rxn-Copolyesters

The material used to make the film should be ductile when stretched, but should also have optimal shrinkage properties. In particular, the shrink curve of the rxn-copolyester should match as closely as possible the shrink curve of the PVC shrink film. To determine adjacency, some of the rxn-copolyesters of Table 3 above were extruded and stretched on a commercial tenter frame. Samples of these stretched films were tested to determine shrinkage as a function of temperature. The strip was cut and then immersed for 30 seconds in a water bath set to a different temperature. The sample was then removed and the shrinkage percentage recorded.

The shrinkage versus temperature for 30 seconds for the rxn-copolyester is plotted to show the "shrinkage curve". This shrinkage curve is shown in FIG. 5 along the shrinkage curve of a commercially available PVC shrink film for comparison (see Table 5 below for reference number in FIG. 5). In the case of PVC, the ideal shrink curve starts at a low temperature and gradually increases in a controlled manner as the temperature increases. Sample 4a was found to be the closest match of the rxn-copolyesters tested, at least visually.

In order to numerically evaluate the optimal composition for PVC, a type of error function was determined that further increased the desired rxn-copolyester shrinkage curve off the PVC curve. This "error function" is the sum of the squares of the errors at each temperature.

Where

The sum relates to the n temperature tested.
The minimum value that the error can reach is zero, meaning that the copolyester shrink curve is completely adjacent to the PVC. The values for the errors are shown in Table 5 below. These errors are curves plotted using least squares regression, and were found to be accurately modeled by Equation 3:

The adjusted R ² for the fit of this curve is 0.98, which represents an overall good prediction of the error data by the above equation. In order to further explain how the error varies with the composition, the model equation is shown in FIG. 6. In addition, experimental contraction data points were placed on the phase. The dividing line represents a constant "error" line. Ideally, a composition present along the dividing line of error = 0 would exhibit a shrinkage behavior consistent with PVC. In practice, however, any composition that is within about 500 error units from the optimal line would probably be acceptable. Note that the dividing line in the upper right corner of FIG. 6 has a negative value for error. This is an artificially illustrated curve since the true error value cannot be less than zero.

Sample number DEG (%) CHDM (%) Reference Number (Figure 5) Shrink Error (Sum of Error Squared) PVC n / a n / a 51 n / a 1a 5.7 24 52 394 2a 4.8 17.4 53 1505 3a 8.2 16.7 54 1135 4a 7.5 23.8 55 156 5a 8.4 19.9 56 309 12a 2 31 57 1319

By setting error = 0 and solving for DEG, the line with error = 0 was determined from model consistency. This gives an equation for determining the optimal mole percent of DEG to CHDM in rxn-copolyester, as shown in Equation 1:

Equation 1

The equation above is used to predict the optimal DEG value for any given CHDM concentration to draw a copolyester shrink curve adjacent to the PVC's shrink curve. Lines with a shrinkage error of -500 to 500 are each at about DEG (%) (optimal) ± 2.5%. In the very wide CHDM range (ie about 15 to about 28 mole percent), the optimal DEG value is within 7.5 to 13 mole percent, which is the range where the rxn-copolyester is softer than the blend (see example above). Corresponds to Thus, in order to have excellent shrinkage properties in addition to ductility, rxn-copolyester compositions are a preferred choice over blends.

Example 7: Improved Drying Method

Drying conditions for the various polymers are shown in Table 6 below. The dew point of the air is −40 ° F. (−40 ° C.) and the flow rate is 1 ft ³ / min (62.37 L / min per kg / hr) per lb / hr of material. As shown in Table 6 below, 6 hours is required to dry the EASTAR PETG copolyester 6763 and rxn-copolyester with a preferred moisture content of 0.08%. Crystalline PET dries faster at 4 hours because the air temperature can be much higher, allowing water molecules to diffuse out of the polymer pellets more quickly. However, when drying the EASTOBOND copolyester 19411 amorphous copolyester, it takes 13 hours or more to reach the same water content as above. The migration of water molecules at 110 ° F. (43.3 ° C.) is not significant, requiring a longer 13 hour drying time. Clearly, drying of the DEG modified PET copolyesters interferes with extruding the PETG copolyester / DEG modified PET copolyester blends.

The rxn-copolyesters of the present invention provide an acceptable substitute for the blend of the '116 patent. An advantage of using rxn-copolyesters is the fact that they can eliminate the difficulty of treating a number of pre-made materials as well as the difficulty of drying amorphous EASTOBOND copolyester 19411.

Property EASTAR PETG 6763 rxn-copolyester EASTOBOND 19411 PET Temperature, ℉ (℃) 150 (66) 150 (66) 110 (43) 300 (149) Hours (hr) 6 6 13 4 Moisture content (%) 0.08 0.08 0.08 0.005

Example 8: b ^* color values

b ^* Color values were measured using a CIELAB color scale with the following parameters: (1) D65 light source, (2) 10 degree observer, (3) built-in mirror and (4) band field of view. b ^* Color values measure yellow when positive and blue when negative. The device used to measure the b ^* color value was the HunterLab Ultrascan Colorimeter, available from the Hunter Associates Laboratory.

b ^* Color values are affected by the sample shape (ie pellet size and shape). Conventional pellets of rxn-copolyester are placed on a 2 cm thick glass sample holder with a black background. Color was measured by reflectance. The pellets were about 2-3 mm in diameter, 2-3 mm in length and 0.8 g / 50 pellets in weight.

Table 7 shows the catalyst composition (ppm) of rxn-copolyester having a composition of 100 mol% terephthalic acid, 25 mol% 1,4-cyclohexanedimethanol, 7 mol% diethylene glycol and 68 mol% ethylene glycol And b ^* color values are compared by changing the composition (ppm) of the red toner and the blue toner.

Sample Titanium (ppm) Manganese (ppm) Phosphorus (ppm) Red (ppm) Blue (ppm) b ^* 14 16 46 40 One 1.5 2.5 15 16 46 50 One 1.5 0.5

Claims (32)

A diacid component containing a residue of at least 90 mol% terephthalic acid when the diacid component is 100 mol%, and When the diol component is 100 mol%, 59 to 77.5 mol% of ethylene glycol, 15 to 28 mol% of 1,4-cyclohexanedimethanol (CHDM) and 7.5 to 13 mol% of diethylene glycol (DEG) Diol component containing residue Reactor grade copolyester composition comprising a. The method of claim 1, A copolyester composition wherein the diol component comprises 16 to 26 mole% 1,4-cyclohexanedimethanol. The method of claim 2, A copolyester composition in which the diol component comprises a residue of diethylene glycol within the range of ± 2.5 mole% of the following formula: Equation 1

The method of claim 1, A copolyester composition having a nominal 2 mil (50 micron) thickness of film at least 300% elongation at break in the non-stretch direction as measured according to ASTM D882. The method of claim 4, wherein Copolyester composition having an elongation of at least 400% at break. A heat shrinkable film comprising the copolyester composition of claim 1. A heat shrinkable film comprising the copolyester composition of claim 3. A film produced by calendering the copolyester composition of claim 1. A diacid component containing a residue of at least 90 mol% terephthalic acid when the diacid component is 100 mol%, and When the diol component is 100 mol%, a diol component comprising a residue of 59 to 77.5 mol% ethylene glycol, 15 to 28 mol% 1,4-cyclohexanedimethanol and 7.5 to 13 mol% diethylene glycol A heat shrinkable film comprising a reactor grade copolyester composition comprising a. The method of claim 9, A heat shrinkable film having a elongation of at least 300% upon failure in the non-stretch direction as measured according to ASTM D882 for a nominal 2 mil (50 micron) thick film. The method of claim 10, Heat shrinkable film having an elongation of 400% or more at break. The method of claim 9 A heat shrinkable film wherein the diol component comprises 16 to 26 mole% 1,4-cyclohexanedimethanol. The method of claim 12, A heat shrinkable film wherein the diol component comprises a residue of diethylene glycol in the range of ± 2.5 mol% of the following equation: Equation 1

The method of claim 9, b ^* heat shrinkable film having a color value of -1.0 to less than 4.5. The method of claim 14, b ^* heat shrinkable film having a color value of -1.0 to 3.5. The method of claim 14, Reactor grade copolyester composition comprises, based on the weight of the copolyester, a residue of a catalyst system comprising 0 to 75 ppm manganese, 10 to 100 ppm titanium and 25 to 150 ppm phosphorus, and 1.0 to 10.0 ppm A heat shrinkable film further comprising a residue of an organic toner system comprising an anthraquinone, which is a red compound of, and a substituted 1,4-bis (2,6-diallylanilino) anthraquinone, which is from 1.0 to 10.0 ppm of a blue compound . The method of claim 16, The catalyst system comprises 15-50 ppm titanium, 20-60 ppm manganese, and 25-150 ppm phosphorus and the organic toner system is 1.0-5.0 ppm red compound anthraquinone and 1.0-5.0 ppm blue compound A heat shrinkable film comprising phosphorous substituted 1,4-bis (2,6-diallylanilino) anthraquinone. Within the range of ± 2.5 mol% of the following formula, and a diacid component comprising a residue of at least 90 mol% terephthalic acid, and 61-82 mol% ethylene glycol, 16-26 mol% 1,4-cyclohexanedimethanol, and A heat shrinkable film comprising a reactor grade copolyester composition comprising a diol component comprising a residue of 2 to 13 mole percent diethylene glycol: Equation 1

The method of claim 18, A heat shrinkable film in which the diacid component comprises at least 95 mol% of terephthalic acid residues. The method of claim 19, A heat shrinkable film in which the diacid component comprises 100 mol% terephthalic acid residues. The method of claim 18, A heat shrinkable film wherein the diol component comprises a residue of 7.5 to 13 mole percent diethylene glycol. Has a b ^* color value of −1.0 to less than 4.5, (a) a diacid component containing a residue of at least 90 mol% terephthalic acid when the diacid component is 100 mol%, (b) a residue of 52 to 88 mol% ethylene glycol, 10 to 28 mol% 1,4-cyclohexanedimethanol and 2 to 20 mol% diethylene glycol when the diol component is 100 mol% A diol component, and (c) the residue of a catalyst system comprising 0 to 75 ppm manganese, 10 to 100 ppm titanium and 25 to 150 ppm phosphorus, and 1.0 to 10.0 ppm red compound, anthra, based on the weight of the copolyester Residue of organic toner system comprising quinone and substituted 1,4-bis (2,6-diallylanilino) anthraquinone which is 1.0-10.0 ppm blue compound Reactor grade copolyester composition comprising. The method of claim 22, b ^* copolyester composition having a color value of -1.0 to 3.5. The method of claim 22, The catalyst system comprises 15-50 ppm titanium, 20-60 ppm manganese, and 25-150 ppm phosphorus and the organic toner system is 1.0-5.0 ppm red compound anthraquinone and 1.0-5.0 ppm blue compound A copolyester composition comprising phosphorus substituted 1,4-bis (2,6-diallylanilino) anthraquinone. The method of claim 22, A copolyester composition wherein the diol component comprises 2 to 13 mole% diethylene glycol residues. The method of claim 25, A copolyester composition wherein the diol component comprises a residue of 7.5 to 13 mole percent diethylene glycol. The method of claim 25, A copolyester composition wherein the diol component comprises 10 to 15 mole% of 1,4-cyclohexanedimethanol residues. The method of claim 25, A copolyester composition in which the diol component comprises 16 to 26 mole% of 1,4-cyclohexanedimethanol residues and a residue of diethylene glycol in the range of ± 2.5 mole% of the following formula: Equation 1

The method of claim 28, A copolyester composition wherein the diol component comprises a residue of 7.5 to 13 mole percent diethylene glycol. delete delete delete

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