KR100233156B1 - Polyester/polyamide blend having improved flavor retaining property and clarity - Google Patents

Abstract

The present invention is directed to polyester / polyamide blends with good gas barrier properties, improved flavor retention and transparency. More specifically, the present application reduces the concentration of acetaldehyde contained in the polyester without generating haze, thereby significantly improving the resistance characteristics, flavor retention and aroma retention of food and the like, and polyethylene terephthalate. Relates to low molecular weight polyamide formulations.

Description

Polyester / polyamide blend with improved flavor retention and transparency {POLYESTER / POLYAMIDE BLEND HAVING IMPROVED FLAVOR RETAINING PROPERTY AND CLARITY}

FIELD OF THE INVENTION

The present invention is directed to polyester / polyamide blends with good gas barrier properties, improved flavor retaining properties and transparency. More specifically, the present application reduces the concentration of acetaldehyde contained in the polyester without generating haze, thereby significantly improving the storage characteristics, flavor retention, and aroma retention of food and the like, and thus polyethylene terephthalate. Relates to low molecular weight polyamide formulations.

Background of the present invention

Polyethylene terephthalate (PET) is widely used for the manufacture of lightweight plastic products because of its excellent mechanical properties, such as formability and creep resistance, and its ability to be biaxially molecularly oriented. However, the polyester is pyrolyzed during the forming and extrusion process to produce acetaldehyde, so that when the polyester is commercialized, the acetaldehyde in the product wall flows into the contents of the product. Acetaldehyde, even in small amounts, adversely affects the flavor retention of foods and beverages, foods, beverages, cosmetics and other packaged contents. For this reason, it is considered desirable to minimize the flow of acetaldehyde into the packaged contents.

Thermoplastic polyesters with good gas barrier properties have been proposed. For example, US Pat. No. 4,398,017 describes copolyesters containing terephthalic acid, isophthalic acid as the acid component and ethylene glycol and bis (2-hydroxyethoxy) benzene as the diol component. However, such gas barrier polyesters used as constituent materials of the container have the function of inhibiting the penetration of gases such as oxygen and carbon dioxide, but do not inhibit the acetaldehyde flowing into foods or beverages, and thus the flavor and aroma of the contents. Only one thing is affected by this.

US Pat. Nos. 4,837,115, 4,052, 481 and 4,501,781 describe methods of using polyamides in polyethylene terephthalate resins for the purpose of improving gas barrier properties.

U.S. Patent No. 4,837,115 describes thermoplastic compositions containing high molecular weight polyamides and polyethylene terephthalates which act to reduce residual acetaldehyde contained in the polyester. U.S. Patent No. 4,837,115 states that the molecular weight of the polyamide is not critical so long as the polyamide has film forming properties. Thus, such polyamides must have a molecular weight high enough to form a film. It is well known in the art that polyamides must have a molecular weight of at least 12,000 to form a film.

U.S. Patent No. 4,052,481 describes resin compositions containing aromatic copolyesters, polyamides and polyalkylene phenylene esters or polyalkylene phenylene ester ethers. Aromatic copolyesters contain terephthalic acid, isophthalic acid and bisphenols.

U.S. Patent Nos. 4,501,781, European counterparts 0212339 and 0092979 describe mixtures containing from 70 to 95 weight percent polyethylene terephthalate resin. In US Pat. No. 4,501,781, the resin mixture is high when 5 to 10% by weight of polyamide resin containing xyylene group is used for PET for the formation of containers with high gas barrier properties without mentioning acetaldehyde. It is said that a container with gas barrier properties cannot be obtained.

The above-mentioned patents are all flawed, since high molecular weight polyamides do not adequately reduce residual acetaldehyde without imparting haze to the polyester. If a small amount of high molecular weight polyamide is used in such a patent, the residual acetaldehyde level will be very high, although the haze may fall to acceptable levels. On the other hand, if a large amount of high molecular weight polyamide is used, residual acetaldehyde may be reduced at the cost of haze.

Contrary to the foregoing, the inventors of the present invention unexpectedly comprise a group consisting of a partially aromatic, low molecular weight polyamide having a number average molecular weight of 15,000 or less and a low molecular weight aliphatic polyamide having a number average molecular weight of 7,000 or less. It has been found that the use of a critically selected polyamide in can reduce the acetaldehyde remaining in the polyethylene terephthalate of the polyester main component more effectively than with a high molecular weight polyamide. Moreover, the low molecular weight polyamides of the present invention do not produce haze when used in critical amounts corresponding to 0.05 to 2.0 weight percent of PET. Therefore, the present invention overcomes the difficulty of lowering residual acetaldehyde only at the expense of haze.

Summary of the invention

Therefore, the first object of the present invention is to improve the flavor retention and aroma retention of the contents in a container made of the polyester by reducing the residual acetaldehyde contained in the polyethylene terephthalate of the polyester main component.

It is a second object of the present invention to provide a polyester / polyamide blend which shows excellent transparency and a process for preparing the blend.

A third object of the present invention is to provide a polyester / polyamide blend and a method for preparing the blend, which show excellent mechanical properties such as impact resistance, stress cracking resistance and heat resistance and excellent fluidity in molding.

The objective is to (A) (1) a dicarboxylic acid component comprising at least 85 mole percent terephthalic acid repeat units and (2) at least 85 mole percent ethylene glycol repeat units (100 mole percent dicarboxylic acid and 100 mole percent diol). 98.0 to 99.95% by weight of a polyester composed of a diol component; And (B) a polyamide selected from the group consisting of low molecular weight aliphatic polyamides having a number average molecular weight of 15,000 or less, partially aromatic, low molecular weight aliphatic polyamides having a number average molecular weight of 7,000 or less, and combinations thereof. To a total weight of (A) and (B), consisting of from 0.05 weight percent to 100 weight percent, by providing a semi-crystalline polyester composition having improved flavor retention.

Detailed description of the invention

The polyester [component (A)] of this invention is polyethylene terephthalate (PET) resin. Copolyesters of PET can also be used. The polyethylene terephthalate resin contains at least 85 mole percent terephthalic acid repeat units and at least 85 mole percent ethylene glycol repeat units (based on 100 mole percent dicarboxylic acid and 100 mole percent diol).

The dicarboxylic acid component of the polyester can optionally be modified with 15 mole percent of a suitable synthetic equivalent, such as one or more different dicarboxylic acids or dimethyl terephthalates other than terephthalic acid. Such additional dicarboxylic acids preferably include C _8-14 aromatic dicarboxylic acids, preferably C _4-12 aliphatic dicarboxylic acids or preferably C _8-12 alicyclic dicarboxylic acids. Examples of dicarboxylic acids that may be included with terephthalic acid include phthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid, cyclohexanedicarboxylic acid, cyclohexanediacetic acid, diphenyl-4,4′-dicarboxylic acid, succinic acid, glutaric acid Acids, adipic acid, azelaic acid, sebacic acid, and the like. Polyesters can be made of two or more of the above dicarboxylic acids.

It is to be understood that the corresponding acid anhydrides, esters and acid chlorides of these acids also fall within the term “dicarboxylic acid”.

The polyester [component (A)] can also optionally be modified with 15 mole percent of one different diol other than ethylene glycol. Such additional diols preferably include C _6-20 alicyclic diols or preferably C _3-20 aliphatic diols. Examples of such diols that may be included with ethylene glycol include diethylene glycol, triethylene glycol, 1,4-cyclohexanedimethanol, propane-1,3-diol, butane-1,4-diol, pentane-1, 5-diol, hexane-1,6-diol, 3-methylpentanediol- (2,4), 2-methylpentanediol- (1,4), 2,2,4-trimethylpentane-diol- (1, 3), 2-ethylhexanediol- (1,3), 2,2-diethylpropane-diol- (1,3), hexanediol- (1,3), 1,4-di- (hydroxyl Methoxy) -benzene, 2,2-bis- (4-hydroxycyclohexyl) -propane, 2,4-dihydroxy-1,1,3,3-tetramethyl-cyclobutane, 2,2-bis- (3-hydroxyethoxyphenyl) -propane and 2,2-bis- (4-hydroxypropoxyphenyl) -propane. Polyesters can be made from two or more of these diols.

Polyethylene terephthalates are also bifunctional or trifunctional comonomers, such as trimethyltriic anhydride, trimethylolpropane, pyromellitic dianhydride, pentaerythritol, and other polyester forming polyacids well known in the art or It may contain small amounts of polyols.

When the inventive formulations are used to produce thermoformed crystallized PET products, it is preferred that the polyester consists essentially of only dimethyl terephthalate and ethylene glycol.

The polyester main component polyethylene terephthalate of the present invention can be produced by conventional polycondensation methods known in the art. Such methods include the direct condensation of dicarboxylic acids with diols or transesterification using dialkyl dicarboxylates. For example, dialkyl terephthalates, such as dimethyl terephthalate, are subject to transesterification with diols at high temperatures and in the presence of a catalyst. The polyester can also be produced by solid phase polymerization.

The second component of the invention is a polyamide selected from the group consisting of low molecular weight aliphatic polyamides having a number average molecular weight of 15,000 or less and partially aromaticized low molecular weight polyamides and a number average molecular weight of 7,000 or less. Combinations of such polyamides are also within the scope of the present invention. “Partially aromatic polyamide” means that the amide linkage of a partially aromatic polyamide contains at least one aromatic ring and non-aromatic species. Partially aromaticized polyamides have I.V. up to 0.8 dL / g. Has Partially aromatic polyamides have an I.V. And a number average molecular weight of 12,000 or less. Aliphatic polyamides have an I.V. Has Aliphatic polyamides have I.V. up to 0.8 dL / g. It is desirable to have a number average molecular weight of less than and 6,000.

The compositions or articles of the invention may contain 2 weight percent or preferably up to 1 weight percent low molecular weight polyamide. It has been found that undesirable amounts of haze and color occur when more than 2 weight percent polyamide is used, based on the weight of the polyester.

Low molecular weight polyamides are isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, meta- or para-xylylene diamine, 1,3- or 1,4-cyclohexane (bis) methylamine, C _6-12 aliphatic amino acids or lactams For example, those made using C _4-12 aliphatic diamines and other known polyamide-forming diacids and diamines can be used. Low molecular weight polyamides may also contain small amounts of bifunctional or trifunctional comonomers such as trimellitic anhydride, pyromellitic dianhydride and other polyamide forming polyacids or polyamines well known in the art. .

Preferred partially aromaticized low molecular weight polyamides are poly (m-xyylene adipamide), poly (hexamethylene isophthalamide), poly (hexamethylene isophthalamide), poly (hexamethylene adipamide-co Isophthalamide), poly (hexamethylene-adipamide-co-terephthalamide) and poly (hexamethylene isophthalamide-co-terephthalamide). Most preferred partially aromatically low molecular weight polyamides have a number average molecular weight of 4,000 to 7,000 and an I.V. of 0.3 to 0.6 dL / g. Poly (m-xyylene adipamide). Preferred low molecular weight aliphatic polyamides include poly (hexamethylene adipamide) and poly (caprolactam). Most preferred low molecular weight aliphatic polyamides are poly (hexamethylene adiamide) having a number average molecular weight of 3,000 to 6,000 and I.V. of 0.4 to 0.9 dL / g.

Partially aromatic low molecular weight polyamides and low molecular weight aliphatic polyamides of the present invention used in combination with polyesters [component (A)] equally reduce the acetaldehyde concentration in products made from the formulation. However, where transparency and dispersibility are important, partially-aromatic low molecular weight polyamides are preferred to aliphatic polyamides.

Low molecular weight polyamides are prepared by in situ melt phase polymerization using a diacid-diamine complex or by melt phase polymerization via a separate step. In either method, diacids and diamines are used as starting materials. In addition, ester forms of diacids, preferably dimethyl esters, can be used. If esters are used, the reaction must be carried out at relatively low temperatures, generally from 80 to 120 ° C., until the esters are converted to amides. Next, the mixture is heated to the polymerization temperature. In the case of polycaprolactam, either caprolactam or 6-aminocaproic acid can be used as starting material, and the polymerization is accelerated by addition of the adipic acid / hexanemethylenediamine salt which forms the nylon 6/66 copolymer. . If a diacid-diamine complex is used, the mixture is heated until it melts and stirred until equilibrium is reached.

The molecular weight is controlled by the diacid-diamine ratio. Excess diamine increases the concentration of terminal amino groups that can be used for reaction with acetaldehyde. If the diacid-diamine complex is prepared in a separate step, excess amine is added prior to polymerization. The polymerization can be carried out at atmospheric or high pressure.

The method for producing the polyester / polyamide blend of the present invention includes a method for producing polyester and low molecular weight polyamide through the above-described method. Polyesters and polyamides are dried under dry air or a dry nitrogen atmosphere or under reduced pressure. Polyester and polyamide are mixed and then melt blended in a single screw or twin screw extruder. The melting temperature should be at least as high as the melting point of the polyester, typically in the range of 260-310 ° C. The melt blending temperature is preferably as low as possible in the above range. The extrudate is taken out in strand form after melt blending and recovered by conventional methods such as cutting. Instead of melt blending, polyester and polyamide may be dry blended and then thermoformed or pressed to plastic products.

Polyamide is added at a later stage of the polyester manufacturing process. For example, the polyamide may be separated from the polycondensation reactor and blended with the molten polyester before it is made into pellets. However, this method is undesirable when the polyester / polyamide blend is the subject of a solid state polymerization method because undesirable color and haze are created when the time at high temperature is increased. In cases where transparency is not important, such as in crystallized thermoformed products, polyamide may also be added as part of the nucleating agent concentrate of the polyolefin main component.

The formulations of the present invention show good appearance as starting materials for the production of all types of extruded or injection molded articles. Specific fields include thermoforming or injection molded trays, leads and cups; Injection stretch blow-out bottles, films and sheets; Packaging fields such as extrusion blown bottles and multilayer products. Examples of packaging contents include, but are not limited to, food, beverages, and cosmetics.

Various other ingredients may be added to the composition of the present invention to improve the performance characteristics of the formulation. These include, for example, crystallization aids, impact modifiers, surface lubricants, denesting agents, stabilizers, antioxidants, ultraviolet absorbers, metal deactivators, colorants such as titanium dioxide and carbon black, and nuclear types such as polyethylene and polypropylene. Agents, phosphate stabilizers, fillers and the like. All of these additives and their use are well known in the art and are not to be discussed. Accordingly, some of the compounds that are understood to not be impeded to achieve the object of the present invention will be selected and mentioned.

In fields where a transparent, non-colored resin is desired, the light yellow color generated during processing may be added with blue dye. The colorant can be added directly to the formulation being also formulated into the components of the formulation being polymerized. Compound colorants can be added in pure form or in concentrate form. The amount of colorant may be adjusted depending on the degree of absorbency of the colorant and the color desired in the particular art. Preferred colorants are 1-cyano-6- (4- (2-hydroxyethyl) anilino) -3-methyl-3H-dibenzo (F, I, J) -isoquinoline-2,7-dione To 15 ppm.

Preferred additives are also impact modifiers and sulfates. Representative commercial impact modifiers well known in the art and useful in the present invention include ethylene / propylene terpolymers, block copolymers of styrene main components, and various acrylic core / shell type impact modifiers. Impact modifiers may be used in conventional amounts of 0.1 to 25 weight percent based on the total composition weight, preferably in amounts of 0.1 to 10 weight percent based on the weight of the composition. Examples of commercially available typical antioxidants useful in the present invention include, but are not limited to, sterically hindered phenols, phosphites, diphosphites, polyphosphites and mixtures thereof. Combinations of aromatic phosphite compounds with aliphatic phosphite compounds may also be included here.

The materials and test procedures used to achieve the results of the present invention are as follows:

Polyester A consists essentially of 0.76 in I.V. Homopolymer of polyethylene terephthalate.

Polyester B essentially has an I.V. Homopolymer of polyethylene terephthalate.

Polyester C consists of 100 mole percent terephthalic acid, 98-99 mole percent ethylene glycol and 1-2 mole percent 1,4-cyclohexanedimethanol, with an I.V. Copolyester with

Acetaldehyde generation (AA Gen) was determined by the following method: Pelletized polyester crystallized at 180 ° C. for 30 minutes was dried in a vacuum oven at 120 ° C. overnight. A Tinius-olsen melt index measuring device was charged with 5 g of polyester and held at test temperature for 5 minutes. The molten polyester was injected into water and stored at −40 ° C. until grinding. The sample was ground to 20 mesh or finer and 0.5 g of it was placed in a sample tube and immediately sealed. Samples were analyzed by dynamic headspace gas chromatography (using Heultt-Packard 5890 gas chromatograph employing Perkin Elmer Thermal Desorption ATD-50 as an injection system). The sample was heated to 150 ° C. for 10 minutes to desorb acetaldehyde. The gas chromatography column had an inner diameter of 30 m x 0.53 mm.

Acetaldehyde concentration (extrusion AA) after extrusion was measured using the same gas chromatography method as mentioned in the acetaldehyde generation measurement after grinding the pellets or sheets to 20 mesh or more finely.

Color was measured by ASTM D2244 method using the Hunter Color Lab instrument. The measurement of color was described by Rd, a and b.

Haze was measured by ASTM D1003 method. A haze value of 3.0% or more indicates visible haze.

The headspace acetaldehyde concentration (HSAA) in the bottle was measured by gas chromatography. The bottles were blow molded, sealed and immediately purged with nitrogen gas. The bottles were stored at a temperature of 20-23 ° C. and a relative humidity of 50% for 24 hours and then tested.

Intrinsic viscosity (I.V.) was measured at 25 ° C. using 0.50 g of polymer per 100 ml of solvent consisting of 60 weight percent phenol and 40 weight percent tetrachloroethane.

The number average molecular weight of polyamide was measured by the boiling point method using hexafluoroisopropanol.

Terminal carboxyl group concentration was determined by potentiometric titration. 1 g of polyamide was placed in 50 ml of benzyl alcohol and heated until dissolved. The titrant was 0.01 N potassium hydroxide in isopropanol.

Terminal amino group concentrations were determined by potentiometric titration. 1 g of polyamide was dissolved in 90 ml of m-cresol at 25 ° C. The titration solution was 0.01 N perchloric acid in isopropanol / propylene glycol (2: 1). The titrant was made using 70% perchloric acid in water.

The invention will be explained in more detail by the following examples which are provided to illustrate the invention. All parts and percentages in the examples are by weight unless otherwise indicated.

Example 1

Poly (hexamethylene adipamide) was prepared by the following method.

A mixture containing 5.19 kg of adipic acid, 6.18 kg of hexamethylenediamine 70% aqueous solution and 3.64 kg of water was prepared. The mixture was placed in a polymerization reactor under nitrogen atmosphere, stirred for 30 minutes, and then heated to 150 ° C. for 60 minutes. The reactor was pressurized to 75 psi (517.13 kPa) and then heated to 275 ° C. and held for 120 minutes. Poly (hexamethylene adipamide) was extruded into water to pulverize and dry. The average molecular weight and I.V. of the poly (hexamethylene adiamide) were 3,600 and 0.61 dL / g, respectively. The concentration of amino end groups was 0.16 mmol / g and the concentration of carboxyl end groups was 0.13 mmol / g.

A blend containing 25 wt% poly (hexamethylene adiamide) and polyester A was prepared by the following method.

The polyamide was dried in a ConAir dryer at 120 ° C. for 16 hours. Polyester A was dried for 16 hours in a ConAir dryer at 120 ℃. 3.97 kg of polyamide and 11.92 kg of Polyester A were dry blended, extruded and pelletized at a melting temperature of 277 ° C. using a 1.25 inch (3.175 cm) stirling single screw extruder equipped with an intermediate screw. The temperatures in zones 1-5 of the extruder were set to 250, 260, 270, 270 and 265 ° C, respectively.

The sheet was extruded from polyester B containing 2.0 to 4.0 wt% of the formulation with 3.0 wt% of polyethylene nucleating agent. Polyester B was dried at 150 degreeC for 4 hours. The polyamide concentrate was dry blended with polyester B and nucleating agent was added using an auxiliary feed system. The extruder was a 3.5 inch (8.89 cm) 24: 1 Prodex extruder with a 100 HP eddy current drive using a Welex 3-roll stack take-off with a 12 inch (30.48 cm) diameter roll. The screw was efficient without mixer. Extrusion conditions were as follows: cylinder zone 1-5 temperature 325, 320, 305, 295 and 295 ° C, gate and head 280 ° C, adapter 280 ° C, die area 1-5 temperature 280 , 260, 260, 260 and 260 ° C., screw speed 35 rpm, roll temperature (normal / middle / bottom) 50/60/70 ° C. The sheet thickness was 30 mil (0.763 mm). Acetaldehyde resulting from the combination is listed in Table I.

Example 2

Poly (hexamethylene adipamide) was prepared according to Example 1 and then blended with Polyester B using the following method.

The poly (hexamethylene adipamide) was ground and dried in a vacuum oven at 120 ° C. for 48 hours. Polyester B was dried for 16 hours in a ConAir dryer at 150 ℃. The polyamide powder was dry blended with the polyester B pellets in the proportions of Table I. The blend was extruded and pelletized at a die temperature of 285 ° C. using a 3/4 inch (1.91 cm) Brabender extruder equipped with a mixing screw. The Brabender extruder is equipped with a mixing screw. Acetaldehyde produced from the combination is listed in Table I.

Example 3

Poly (hexamethylene adiamide) was prepared by the following method.

A mixture was prepared containing 5.05 kg of adipic acid, 6.31 kg of 70% hexamethylenediamine aqueous solution and 3.64 kg of water. The mixture was reacted and extruded as in Example 1. The number average molecular weight and I.V. of poly (hexamethylene adiamide) were 2,500 and 0.43 dL / g, respectively. The amino terminal group concentration was 0.28 mmol / g, and the carboxyl end group concentration was 0.13 mmol / g.

A blend with polyester B was prepared by the method of Example 2 using poly (hexamethylene adipamide) prepared by the above method. The acetaldehydes produced from the combinations are listed in Table I.

Example 4

Poly (hexamethylene adiamide) was prepared by the following method. A mixture was prepared containing 4.93 kg of adipic acid, 6.44 kg of 70% hexamethylene diamine aqueous solution and 3.64 kg of water. The mixture was reacted and extruded as in Example 1. The number average molecular weight and I.V. of the poly (hexamethylene adipamide) were 2,300 and 0.31 dL / g, respectively.

A blend with polyester B was prepared in the same manner as in Example 2 using poly (hexamethylene adipamide) prepared by the above method. Acetaldehyde produced from the combination is listed in Table I.

Example 5

I.V. in Polyester A. Prepared by the method of Example 1 a blend containing 25 wt% of commercially available poly (hexamethylene adipamide) having 1.2 dL / g and a number average molecular weight of 20,000.

The sheet was extruded by the method of Example 1 from polyester B containing the said formulation. The acetaldehydes produced from the combinations are listed in Table I.

Example 6

I.V. Prepared a blend with Polyester B by the method of Example 2 using 1.2 dL / g and commercially available poly (hexamethylene adipamide) having a number average molecular weight of 20,000. The test results are listed in Table I.

Table I

The results in Table I clearly show that the polyethylene terephthalate type formulations containing poly (hexamethylene adipamide) have reduced acetaldehyde concentrations. In addition, the use of a critical amount of the low molecular weight (measured by IV) poly (hexamethylene adipamide) polyamide of the present invention rather than the high molecular weight polyamides used in Examples 5 and 6 further reduced the acetaldehyde concentration in the polyester. effective. Moreover, Examples 2, 3 and 4 illustrate the inverse relationship between the molecular weight of polyamides and the effectiveness of reducing acetaldehyde concentrations.

Example 7

Poly (caprolactam), nylon-6, was prepared by the following method. A mixture containing 131.0 g aminocaproic acid and 60.0 g water was prepared. The mixture was placed in a polymerization reactor under nitrogen atmosphere and stirred for 30 minutes while heating to reflux. Water was distilled off and the mixture was heated to 275 ° C. and held for 30 minutes. The mixture was stirred at 275 ° C. for 20 minutes. I.V. of polycaprolactam was 0.47 dL / g and number average molecular weight 5,000. The I.V. of poly (caprolactam) obtained by extending the final stage of the reaction to 30 minutes was 0.63 dL / g.

A blend with polyester B was prepared using poly (caprolactam) obtained by the above method. The polyamide was ground and dried in a vacuum oven at 120 ° C. for 48 hours. Polyester B was dried for 16 hours in a ConAir dryer at 150 ℃. The polyamide powder was dry blended with the polyester B pellets at a concentration of 0.5 wt%. The blend was extruded using a 3/4 inch (1.91 cm) Brabender extruder equipped with a mixing screw at a die temperature of 285 ° C. Acetaldehyde produced from the combination is listed in Table II.

Example 8

I.V. Was blended with polyester B in the manner described in Example 7 using a commercially available poly (caprolactam) of 1.3 dL / g. Acetaldehyde produced from the combination is listed in Table II.

Table II

The results in Table II clearly show that the acetaldehyde concentration of the polyethylene terephthalate type formulations containing poly (caprolactam) was reduced. In addition, the results indicate that the use of a critical amount of the low molecular weight (measured by IV) poly (caprolactam) polyamide of the present invention is more effective than the high molecular weight polyamide used in Example 8 in reducing acetaldehyde concentration in polyester. .

Example 9

Poly (m-xylylene adiamide) was prepared by the following method. A mixture containing 4.32 kg of adipic acid, 4.82 kg of m-xylylenediamine and 7.72 kg of water was prepared. The mixture was placed in a polymerization reactor under a nitrogen atmosphere. The mixture was heated at reflux for 30 minutes with stirring. The mixture was heated to 120 ° C. and then distilled while maintaining for 60 minutes. The temperature was then raised to 275 ° C. over a 3.25 hour period. The mixture was heated at 275 ° C. for 30 minutes. Poly (m-xylylene adiamide) was extruded into water to pulverize and dry. The number average molecular weight and I.V. of the poly (m-xylylene adiamide) were 2,300 and 0.27 dL / g, respectively.

A concentrate containing 25 wt% of polyamide in Polyester A was prepared using poly (m-xylylene adiamide) prepared by the above method. The polyamide was ground and dried in a vacuum oven at 120 ° C. for 16 hours. Polyester A was dried for 16 hours in a ConAir dryer at 150 ℃. The polyamide powder was dry blended with polyester A pellets at 0.5 and 1.0 wt% concentrations. The blend was extruded and pelletized at a die temperature of 260-275 ° C. using a 1.25 (3.175 cm) inch Killion single screw extruder.

Sheets were extruded from polyester B containing 2.0 and 4.0 wt% of the blend and 3.0 wt% of polyethylene nucleating agent. Polyester B was dried at 150 degreeC for 4 hours. Polyamide concentrate was dry blended with polyester B and nucleating agent was added using a supplemental feed system. The extruder used a 24: 1 Prodex extruder equipped with a 100 HP eddy current drive using a Welex 3-roll stack take-off with 3.5 inch (8.89 cm), 12 inch (30.48 cm) diameter rolls. The screw was of type efficiency without a mixer. Extrusion conditions are: cylinder zones 1-5 temperatures of 310, 315, 300, 290 and 290 ℃, gate and head 265 ℃, adapter 265 ℃, die zones 1-5 temperatures of 275, 270, 270, 270 and 270 ° C., screw speeds of 31, 32 and 35 rpm at 0, 2 and 4 wt% polyamide concentrations, and 55, 60 and 60 ° C. roll temperatures at top, middle and bottom, respectively. Sheet thickness 30 mil (0.763 mm).

The trays were thermoformed using a 24 inch (60.96 cm) Lyle continuous roll-feed thermoformer fitted to enable hot mold / cold mold. Thermoforming conditions were as follows: heater zones 1-8 temperatures were 415, off, 350, 260, 260, 350 ° C. and off, hot mold 205 ° C., cold mold 77 ° C., polyamide concentration 0.2 and The cycle times at 4 wt% were 3.95, 3.90 and 4.10 seconds, respectively.

PET trays thermoformed in this manner contained 0.5 ppm acetaldehyde for 0.5 wt% polyamide, 0.2 ppm acetaldehyde for 1.0 wt% polyamide, and 12.2 ppm acetaldehyde without polyamide. . Thus, the low molecular weight polyamides of the present invention, used in critical amounts, reduced the acetaldehyde concentration by six-fold in the thermoformed crystallized PET tray.

Example 10

Poly (m-xylylene adiamide) was prepared by the following method. A mixture was prepared containing 43.8 g of adipic acid, 53.0 g of m-xylylenediamine (30% molar excess) and 50.0 g of water. The mixture was placed in a 500 ml flask under nitrogen atmosphere. The mixture was heated at reflux for 20-30 minutes with stirring. The water was distilled off and the temperature was raised to 275 ° C. for 30 minutes. The mixture was stirred at 275 ° C. for 30 minutes. The poly (m-xylylene adiamide) produced by this method had an I.V. of 0.20 dL / g.

A blend of poly (m-xylylene adiamide) and polyester C prepared as described above was prepared by the following method.

The polyamide was ground and then dried in a vacuum oven at 120 ° C. for 48 hours. Polyester C was dried for 16 hours in a ConAir dryer at 150 ℃. The polyamide powder was dry blended with the polyester C pellets at concentrations of 0.1, 0.3 and 0.5 wt%. The blend was extruded and pelletized at a die temperature of 270 ° C. using a 3/4 inch (1.91 cm) Brabender extruder equipped with a mixing screw. Acetaldehyde produced from the combination is listed in Tables III and VI.

The bottle was prepared by the following method. 10 g of poly (m-xylylene adiamide) and 1990 g of polyethylene terephthalate prepared as described above were dry blended with polyester C. The preformed bottles were injection molded at a melt temperature of 275 ° C. using a Cincinnati Milacron Model PC-3 molding machine equipped with a single preform molding mold. The preform was reheat blow molded to make a 1 / 2-liter bottle. Acetaldehyde produced from the head space, sidewall haze and combination of the bottles is in Table VI.

Example 11

Poly (m-xylylene adiamide) was prepared by the following method. A mixture containing 43.80 g of adipic acid, 48.96 g of m-xylylenediamine (20% molar excess) and 50 g of water was prepared. The mixture was prepared and polymerized in the manner described in Example 10. Poly (m-xyylene adipamide) is I.V. Was 0.26 dL / g and the number average molecular weight 3,500.

A blend of poly (m-xylylene adiamide) and polyester C was prepared as in Example 10. The acetaldehydes produced from the combinations are listed in Table III.

Example 12

Poly (m-xylylene adiamide) was prepared by the following method. A mixture was prepared containing 43.80 g adipic acid, 43.86 g m-xylylenediamine (7.5% molar excess) and 50 g water. The mixture was prepared and polymerized as in Example 10. Poly (m-xyylene adipamide) is I.V. Was 0.44 dL / g and the number average molecular weight 5,000.

A blend of poly (m-xylylene adiamide) and polyester C was prepared as in Example 10. Acetaldehyde produced from the combination is listed in Tables III and VI.

The bottle was prepared as in Example 10. Acetaldehyde produced from bottle headspaces, sidewall hazes, and blends is listed in Table VI.

Example 13

Poly (m-xylylene adiamide) was prepared by the following method. A mixture containing 43.80 g of adipic acid, 42.84 g of m-xylylene diamine (5% molar excess) and 50.0 g of water was placed in a 500 ml flask under nitrogen atmosphere. The mixture was prepared and polymerized according to the method of Example 10. I.V. of poly (m-xylylene adiamide) was 0.53 dL / g, and the number average molecular weight was 7.030. The concentration of amino end groups was 0.13 mmol / g and the concentration of carboxyl end groups was 0.035 mmol / g. A blend of poly (m-xylylene adiamide) and polyester C was prepared as in Example 10. Acetaldehyde produced from the combination is listed in Table III.

Example 14

Poly (m-xylylene adiamide) was prepared by the following method. A mixture containing 43.80 g adipic acid, 41.82 g m-xylylene diamine (2.5% molar excess) and 50 g water was placed in a 500 ml flask under nitrogen atmosphere. The mixture was prepared and polymerized by the method of Example 10. Poly (m-xylylene adiamide) had an I.V. of 0.70 dL / g and a number average molecular weight of 10500. The concentration of the amino terminal group was 0.049 mmol / g, and the concentration of the carboxyl terminal group was 0.039 mmol / g.

A blend of poly (m-xylylene adiamide) and polyester C was prepared as in Example 10. Acetaldehyde produced from the combination is listed in Table III.

Example 15

Poly (m-xylylene adiamide) was prepared by the following method. A mixture containing 51.10 g of adipic acid, 48.79 g of m-xylylenediamine and 60.0 g of water was prepared. The mixture was prepared and mixed by the method of Example 10. I.V. of poly (m-xylylene adiamide) was 1.0 dL / g and number average molecular weight 22,000.

A blend of poly (m-xylylene adiamide) with polyester C was prepared as in Example 10. Acetaldehyde produced from the combination is listed in Tables III and VI.

The bottle was prepared as in Example 10. Acetaldehyde produced from bottle headspaces, sidewall hazes and blends is in Table VI.

TABLE III

The results in Table III show that the polyethylene terephthalate type formulations containing poly (m-xylylene adiamide) have reduced acetaldehyde concentrations. In addition, this result indicates that the use of a critical amount of the low molecular weight poly (m-xylylene adiamide) polyamide of the present invention will more effectively reduce the acetaldehyde concentration in the polyester than the high molecular weight polyamide used in Example 15. Tells you that you can. Moreover, Examples 10-14 show that the effectiveness of reducing polyamide molecular weight and acetaldehyde concentration is inversely related.

Example 16

IV prepared in Example 1 blended 0.61 poly (hexamethylene adipamide) with polyester B, polyethylene nucleating agent and TiO ₂ . The blend was extruded into a film using the following method.

The poly (hexamethyleneadipamide) was ground and then dried in a vacuum oven at 120 ° C. for 48 hours. Polyester B was dried for 16 hours in a ConAir dryer at 150 ℃. TiO ₂ was added as a 50 wt% blend in Polyester A. The TiO ₂ blend was dried for 48 hours in a vacuum oven at 120 ° C. All formulations contained 3.3 wt% polyethylene nucleating agent. The concentrations of polyamide and TiO ₂ are listed in Table IV. The ingredients were dry blended and extruded into a 30 mil (0.763 mm) film at a die temperature of 285 ° C. using a Killion 1.25 inch (3.175 cm) extruder. Film samples were crystallized in a forced air circulation oven at 180 ° C. The color measurement results for the crystallized film are in Table IV.

The blend of 3.3 wt% polyethylene nucleating agent, 0.75 wt% poly (hexamethyleneadipamide) with an intrinsic viscosity of 0.61, and polyester B containing 0.1 wt% TiO ₂ was fitted with mixing screws with dry blended components. By extrusion at a die temperature of 285 ° C. using an isolated 3/4 inch (1.91 cm) Brabender extruder. For PET containing only nucleating agent and no polyamide or TiO ₂ , the blend has 1.0 ppm pellet AA as compared to 7.7 ppm pellet AA.

Table IV

The results in Table IV showed that the milkyness of the polyethylene terephthalate blend containing polyamides such as poly (hexamethylene adiamide) was improved by adding titanium dioxide. Moreover, the addition of titanium dioxide reduces the yellowness of these formulations.

Example 17

Poly (m-xylylene adiamide) was prepared by the following method. A mixture was prepared containing 2.69 kg of adipic acid, 2.76 kg of m-xylylene diamine (10% molar excess) and 4.82 kg of water. The mixture was placed in a polymerization reactor under nitrogen atmosphere. The mixture was heated at reflux for 30 minutes with stirring. The mixture was heated to 120 ° C. and held for 60 minutes to distill the water. The temperature was then raised to 275 ° C. for 3.25 hours. The mixture was stirred at 275 ° C. for 30 minutes. Poly (m-xylylene adiamide) was extruded into water, milled and dried. The number average molecular weight and intrinsic viscosity of the poly (m-xylylene adiamide) were 6.730 g / mole and 0.41 dL / g, respectively.

A blend with poly (m-xylylene adiamide) polyester C thus prepared was prepared by the following method.

The polyamide was pulverized and dried in a vacuum oven at 120 ° C. for 48 hours. Polyester C was dried for 16 hours in a ConAir dryer at 150 ℃. The polyamide powder was dry blended with the polyester C pellets at a concentration of 0.5 wt%. The blend was extruded and pelletized at a die temperature of 270 ° C. using a 3/4 inch (1.91 cm) Brabender extruder equipped with a mixing screw. Acetaldehyde produced from the combination is in Table VI.

The bottle was prepared by the following method. 0.34 kg of the poly (m-xylylene adiamide) prepared above was weighed in 65.58 kg of polyester C and 250 ppm of 1-cyano-6- (4- (2-hydroxyethyl) anilino) -3-methyl. 3H-dibenzo (F, I, J) isoquinoline -2,7-dione combined with 2.18 kg of concentrate containing 2,7 dione. The blend contained 8 ppm of colorant. 1-cyano-6- (4- (2-hydroxyethyl) -anilino) -3-methyl-3H-dibenzo (F, I, J) in the PET batch during the polymerization after the transesterification step before the polycondensation step The concentrate was prepared by adding isoquinoline-2,7-dione. PET bases for concentrates were prepared from dimethyl terephthalate and ethylene glycol using standard melt phase synthesis. The polyester resin was dried in a forced air circulation dryer. The bottle preforms were molded in a two step stretch blow molding process on a Husky XL225 injection molding machine equipped with eight cavity preform molds. The bottle preform was molded at a melting temperature of 275-300 ° C. The preforms were stored for 24 hours at ambient temperature before the bottling step. The preform was reheated and blown using a quartz lamp. The preform was heated to a temperature slightly above the glass transition temperature and blown into a 2-liter bottle-shaped mold. Acetaldehyde produced from bottle headspaces, sidewall hazes and formulations is listed in Table V. Each formulation was measured eight times and the standard error for the headspace acetaldehyde residual (HSAA) for the eight bottles is given in parentheses.

Table V

The data in Table V show a slight increase in haze with the polyamides of the present invention. Increasing the melting temperature also increases the amount of acetaldehyde produced.

Example 18

Poly (m-xylylene adiamide) was prepared by the following method. A mixture containing 43.80 g of adipic acid, 46.92 g of m-xylylene diamine (15% molar excess) and 50.0 g of water was placed in a 500 ml flask under nitrogen atmosphere. The mixture was prepared and polymerized according to the method of Example 10. Poly (m-xyylene adipamide) is I.V. Was 0.31 dL / g and the number average molecular weight was 3.050 g / mole. The concentration of the amino terminal group was 0.42 mmol / g and the concentration of the carboxyl terminal group was 0.011 mmol / g.

A blend of poly (m-xylylene adiamide) and polyester C was prepared as in Example 17. Acetaldehyde produced from the combination is listed in Table VI.

The bottle was prepared as in Example 10. Acetaldehyde produced from bottle headspaces, sidewall hazes, and blends is listed in Table VI.

Example 19

Poly (hexamethylene isophthalamide) was prepared by the following method. A mixture containing 98.7 g of a previously prepared salt of isophthalic acid and hexamethylenediamine, a 70% aqueous solution of hexamethylene diamine (15% molar excess) and 60 g of water was placed in a 500 ml flask under nitrogen atmosphere. The mixture was heated at reflux for 20-30 minutes with stirring. The water was distilled off and the temperature was raised to 285 ° C. for 30 minutes. The mixture was stirred at 285 ° C. for 30 minutes. Poly (hexamethylene isophthalamine) was extruded into water, pulverized and dried. I.V. of poly (hexamethylene isophthalamine) was 0.15 dL / g and the number average molecular weight 1,800.

The blend of poly (hexamethylene isophthalamide) and polyester C thus prepared was prepared by the following method.

The polyamide was ground and dried in a vacuum oven at 120 ° C. for 48 hours. Polyester C was dried for 16 hours in a ConAir dryer at 150 ℃. The polyamide powder was dry blended with the polyester C pellets at a concentration of 0.5 wt%. The blend was extruded and pelletized at a die temperature of 270 ° C. using a 3/4 inch (1.91 cm) Brabender extruder equipped with a mixing screw. Acetaldehyde produced from the combination is listed in Table VI.

The bottle was prepared as in Example 10. Acetaldehyde produced from bottle headspaces, sidewall hazes, and blends is listed in Table VI.

Example 20

MXD6 polyamide from Mitsubishi Gas Chemical Company, I.V. Was pulverized Grade II 600 1 with 0.85 and number average molecular weight of 18,000 and dried in a vacuum oven at 120 ° C. for 48 hours. Drum and tumble with dried polyamide powder and polyester C to produce 0.25 and 0.5 wt% MXD6 polyamide blends. The preform was injection molded at a melt temperature of 287 ° C. with a Husky XL225 injection molding machine equipped with eight cavity preform molds. The preform was reheated and injection molded into a 2-liter bottle. Acetaldehyde produced from bottleheadspace, sidewall haze and blends is in Table VI.

Example 21

I.V. The commercially available poly (caprolactam) of 1.4 dL / g and a number average molecular weight of 24,000 was pulverized and then dried in a vacuum oven at 120 ° C. for 48 hours.

The bottle was prepared as in Example 11. Acetaldehyde produced from bottle headspaces, sidewall hazes, and blends is listed in Table VI.

Example 22

MXD6 polyamide from Mitsubishi Gas Chemical Company, I.V. Was pulverized Grade # 6001 with 0.85 dL / g and number average molecular weight of 18,000 and dried in a 120 ° C. vacuum oven for 48 hours.

The bottle was prepared as in Example 11. Acetaldehyde produced from bottle headspaces, sidewall hazes, and blends is listed in Table VI.

Table VI

The results in Table VI show that using a critical amount of the low molecular weight polyamide of the present invention is more effective in reducing the acetaldehyde concentration in the PET main component polyester than the high molecular weight polyamide used in Examples 15 and 20-22. At the same time, the low molecular weight polyamides of the present invention used in critical amounts do not exhibit any visible haze. For example, when the low molecular weight polyamide of the present invention is used, the haze is 3 or less and the headspace acetaldehyde value is 1 or less. In contrast, Examples 15 and 20-22 used as comparative examples were unable to obtain low headspace acetaldehyde values and low haze simultaneously. The problem with the comparative example is that if a small amount of high molecular weight polyamide is used, acceptable haze is obtained but the residual acetaldehyde is very large. On the other hand, when a large amount of high molecular weight polyamide is used, the residual acetaldehyde is reduced but the haze is worse. Therefore, the present invention overcomes the problem that low residual acetaldehyde can be obtained only by abandoning the haze.

Many modifications may be made to those skilled in the art from the above detailed description. All such modifications are intended to fall entirely within the scope of the appended claims.

Claims (2)

(A) a dicarboxylic acid component comprising at least 60 mole percent terephthalic acid repeat units and (2) a diol component containing at least 50 mole percent ethylene glycol repeat units (100 mole percent dicarboxylic acid and 100 mole percent 1 to 90 weight percent polyester, consisting of diols; And (B) polyamides selected from the group consisting of low molecular weight aliphatic polyamides having a number average molecular weight of less than 15,000 and partially aromatic aliphatic polyamides having a number average molecular weight of less than 7,000 and combinations thereof; 99 weight percent and the total weight of (A) and (B) is 100 weight percent], wherein the low molecular weight aliphatic polyamide is selected from the group consisting of poly (hexamethylene adipamide) and poly (caprolactam) And partially aromaticized low molecular weight polyamides are poly (m-xyylene adipamide), poly (hexamethylene isophthalamide), poly (hexamethylene adipamide-co-isophthalamide), poly (Hexamethylene adipamide-co-terephthalamide) and poly (hexamethylene isophthalamide Polyamide concentrate useful for preparing polymer blends with improved flavor retention, assuming that it is selected from the group consisting of: id-co-terephthalamide). (A) a dicarboxylic acid component comprising at least 95 mole percent terephthalic acid repeat units and (2) a diol component containing at least 95 mole percent ethylene glycol repeating units (100 mole percent dicarboxylic acid and 100 mole percent 1 to 90 weight percent of a polyester composed of diol); And (B) poly (m-xylylene adipamide), poly (hexamethylene isophthalamide), poly (hexamethylene adipamide-co-isophthalamide), poly (hexamethylene adipamide-co-terephthalamide Amides) and poly (hexamethylene isophthalamide-co-terephthalamide) having a number average molecular weight of less than 15,000 and partially aromaticized low molecular weight polyamides and poly (hexamethylene adipamides) and The total weight of [(A) and (B) consisting of 10 to 99 weight percent polyamide selected from the group consisting of low molecular weight aliphatic polyamides having a number average molecular weight of less than 7,000 selected from the group consisting of poly (caprolactam) 100 weight percent], polymer blend with improved flavor retention Polyamide concentrate useful for manufacturing.