EP0397796A1 - Blends of poly(etheresters) and polyesters and articles made therefrom - Google Patents

Abstract

Compositions comprising a mixture of (A) 98-2% by weight of a flexible polyetherester having repeating units originating from a 1,4-cyclohexane dicarboxylic acid having a trans isomer content of at least 70% , a glycol constituent composed essentially of 1,4-cyclohexanedimethanol and poly (oxytetramethylene) glycol, (B) 2-98% by weight of a relatively rigid polyester, these mixtures having an improved stiffness and resilience according to Izod compared to poly (etherester) alone. Also described are sheet materials adapted to be bonded to a substrate, said materials comprising a support sheet of the aforementioned mixture, having on one side a decorative and / or protective coating.

Description

BLENDS OF POLY(ETHERESTERS) AND POLYESTERS AND ARTICLES MADE THEREFROM

Technical Field This invention relates to blends of flexible poly(etheresters) and rigid polyesters having unexpected levels of stiffness and notched Izod impact strength when compared with these properties of the poly(etherester) alone. This invention further relates to articles made from such blends.

Background of the Invention

A particular advantage of the blends of the present invention is in their use in forming sheet material to be used as a carrier for decorative and/or protective coatings.

The need for spray painting operations to provide the necessary protective and decorative coating on automotive panels may be eliminated according to this invention. Elimination of spray painting, or a substantial reduction in the extent of its use, would not only be environmentally beneficial in reducing atmospheric pollution, but would be extremely beneficial from a cost savings standpoint in that spray painting operations are wasteful of the paint to such an extent that more than half of the paint may be lost as waste material. A means for achieving such goal exists through the use of a thermoplastic sheet material which can be glued or otherwise securely bonded to the panel to provide the protective and decorative coating. Such techniques are known, and have been utilized for such purposes as interior automobile panels as described, for example, in U.S. Patent No. 3,551,232. To employ a process of the type described in U.S. Patent No. 3,551,232 with automotive panels presents a much greater challenge. The surface appearance of such panels is of critical importance, so that it is necessary not only to avoid such problems as bubbling or blistering caused by entrapped air, but to provide a protective and decorative coating that will equal or exceed in many respects, the quality of a spray—painted surface. Furthermore, automotive panels present a particular problem in view of the great difficulty of smoothly adhering a flexible sheet material to a substrate which may possess complex curvature and the even greater difficulty of doing so while maintaining over the entire surface of the panel a uniform degree of the color intensity exhibited by the coating.

The present invention provides sheet material which can be securely bonded to substrate panels to provide the protective and decorative coating as disclosed in the patent mentioned above. However, the present invention is an improvement in that it provides desirable physical properties to the sheet material, particularly improved stiffness and impact strength. In such applications, it is desirable for the sheet material to possess a certain degree of stiffness to be more compatible with the support panel. This is true for both in-molding processing (where the sheet is first placed in a mold against a surface thereof and subsequently flowable material is introduced into the mold and solidified), and for processing by simply placing the sheet on a substrate panel and establishing a bond therebetween.

It is further obviously desirable that the sheet material have good impact strength, especially in parts such as bumpers, so that permanent indentations and/or fractures will not occur when struck by hard objects.

The present invention provides blends of poly(etherester) and polyesters which are especially useful in formation of the carrier sheet referred to above due to the improved properties of stiffness and impact strength.

Poly(etheresters) of trans—1,4—cyclohexanedi— carboxylic acid, 1,4-cyclohexanedimethanol, poly(oxytetramethylene) glycol and a branching agent are disclosed in U.S. Patent No. 4,349,469. Other patents of interest include U.S. Patent

Nos. 4,003,882; 3,261,812; 3,023,192; 4,221,703;

3,651,014; and 4,256,860. None of these patents, however, suggests that the flexible polyesters described above would show improved physical properties if blended with certain polyesters as described herein.

Description of the Drawing

Figure 1 is a cross section of a finished structure utilizing a carrier sheet of the blend according to the present invention.

Disclosure of the Invention

The blends according to this invention are particularly useful in thermoforming processes, where the blends are first formed into a sheet and subsequently thermoformed by the application of heat and pressure, using conventional well known techniques, to form the finished article. Also, the presence of the relatively rigid polyester (a less crystalline polymer) in the blend makes the blend more easily thermoformed. The blends are also useful in conventional injection molding and extrusion applications. According to the present invention, there are provided blends of a flexible poly(etherester) with a more rigid polyester, the blends characterized by containing (A) 98-2 weight % of a flexible poly(etherester) having an I.V. of 0.8—1.5 and recurring units from

(1) a dicarboxylic acid component consisting essentially of 1,4—cyclohexanedicarbox lie acid having a trans isomer content of at least 70%,

(2) a glycol component consisting essentially of

(a) 95 to 65 mol % 1,4—cyclohexanedi— methanol, and

(b) 5 to 35 moϊ % poly(oxytetra— methylene) glycol having a molecular weight of 500 to 1100, and (B) 2-98 weight % of a relatively rigid polyester having recurring units from 80—100 mol % terephthalic acid and at least one aliphatic or cycloaliphatic glycol having 2—12 carbon atoms, said polyester having an I.V. of 0.5-1.0, the blends having improved stiffness when compared to the poly(etherester) alone.

Moreover, it has also been found that the blends have unexpectedly improved notched Izod impact strengths when compared to the poly(etherester) alone when the blends contain 98-60 wt % of the flexible poly(esterether) and 2—40 wt % of the relatively rigid polyester.

The dibasic acid component of the poly(esterether) of this invention consists essentially of 1,4—cyclohexanedicarboxylic acid having a trans isomer content of at least 70%, preferably at least 80% and most preferably at least 85% trans isomer content. 1,4—Cyclohexanedicarboxylic acid and

1,4—cyclohexanedimethanol are well known in the art and commercially available. "Man-Made Fibers: Science and Technology," Vol. Ill, edited by Mark, Atlas and Cernia, published by Interscience Publishers describes preparation of 1,4—cyclohexanedicarboxylic acid and 1,4—cyclohexanedimethanol at page 85.

The poly(oxytetramethylene) glycol component of this invention is commercially available, and is prepared by well known techniques. The poly(oxytetramethylene) glycol has a molecular weight of between 500 and 1100, preferably 1000 (weight average). It is used in an amount of from 5 to 35 mol %, preferably 8—15%, based on the total glycol mol %. The poly(esterether) of this invention further may comprise up to 1.5 mol %, based on the acid or glycol component, of a polybasic acid or polyhydric alcohol branching agent having at least three COOH or OH functional groups and from 3 to 60 carbon atoms. Esters of many such acids or polyols may also be used. Suitable branching agents include trimellitic acid or anhydride, trimesic acid, trimethylol ethane, trimethylol propane, and trimer acid.

It should be understood that the total acid reactants should be 100 mol %, and the total glycol reactants should be 100 mol %. Although the acid reactant is said to "consist essentially of" 1.4—cyclohexanedicarboxylic acid, if the branching agent is a polybasic acid or anhydride, it will be calculated as part of the 100 mol % acid. Likewise, the glycol reactant is said to "consist essentially of" 1,4—cyclohexanedimethanol and poly(oxytetra— methylene) glycol, if the branching agent is a polyol, it will be calculated as part of the 100 mol- % glycol.

The poly(esterethers) of this invention preferably include a phenolic antioxidant. It is preferred that the phenolic antioxidant be hindered and relatively non—volatile. Tetrakis[methylene— (3,5-di—tert—butyl— -hydroxyhydrocinnamate)methane] which is commercially available from Geigy Chemical Company as Irganox 1010 antioxidant, is preferred. Preferably, the antioxidant is used in an amount of from 0.1 to 1.0, based on the weight of copolyester— ether.

The trans and cis isomer contents of the final copolyesterether are controlled in order to give polymers that setup or crystallize rapidly. Cis and trans isomer contents are measured by conventional methods well known to those skilled in the art. See, for example, U.S. Patent No. 4,349,469.

The poly(etherester) used in this invention may be prepared by conventional techniques. See, for example, U.S. Patent No. 4,349,469. The polyester used in this invention may be prepared by conventional techniques using an acid component consisting essentially of terephthalic acid. Minor amounts of other conventionally used dicarboxylic acids (up to 10%) such as isophthalic, naphthalene dicarboxylic or aliphatic dicarboxylic acids having 4 to 12 carbon atoms may be used. Conventional glycols, or combinations of glycols for copolymers, having 2 to 12 carbon atoms may be used. The preferred glycols are ethylene glycol, 1,4—butanediol and 1,4—cyclohexanedimethanol, and combinations thereof. Especially preferred glycols are ethylene glycol and 1,4—cyclohexanedimethanol and combinations thereof. The I.V. of the polyester is ^* .5-1.0. The flexible ρoly(etherester) and rigid polyester may be combined by conventional plastic melt-mixing methods such as, for example, melt blending using an extruder. The blends are useful in injection molded articles, such as fascia and tubing, and sheet material for thermoformed articles.

The sheet material made from the blends described above may be used in the manner shown in Figure 1. The carrier sheet is produced from the blends described above. It is first provided with a decorative and/or protective coating, which may conveniently be a suitable point. The optional topcoat, which may be used as a protective coating or to provide glass, may be used if desired. The coatings may be applied by conventional means known to those skilled in the art. Upon formation of the layered sheet material, it may be applied to a substrate panel by in—mold processing or simple bonding as described hereinbefore. If desired, and depending on the composition of the substrate, an adhesive or tie layer may be used to facilitate the bond.

The following examples are submitted for a better understanding of the invention. In the examples, the Polymer "X" is described as having an I.V. of 1.23 and recurring units from

99.5 mol % 1,4—cyclohexanedicarboxylic acid (trans content 90%) 0.5 mol % trimellitic anhydride 91.1 mol % 1,4—cyclohexanedimethanol 8.9 mol % poly(oxytetramethylene) glycol having a molecular weight of 1000 Polymer "Y^u is described as a polyester having an I.V. of 0.75 and recurring units from

100 mol % terephthalic acid

68 mol % 1,4—cyclohexanedimethanol 32 mol % ethylene glycol

Polymer "Z" is described-as a polyester having an I.V. of 0.75 and recurring units from

100 mol % terephthalic acid

69 mol % ethylene glycol

31 mol % 1,4—cyclohexanedimethanol

Exam les

Example 1. .Polymer X is blended in varying ratios with Polymer Y by mixing pellets then compounding on a single screw extruder. The resulting blend is injection molded into bars for testing. Surprisingly, it was found that the flexural modulus, measured according to ASTM D790, of the blends was higher than the expected values. It may be observed that the values actually obtained on the blends are above the expected values.

Another surprising result is the notched Izod impact strength (ASTM D256) at 23°C, As shown in Table 1 below, the impact strength of Polymer X is substantially increased by addition of even small amounts of Polymer Y.

Polymer X and Polymer Z. The flexural modulus is again unexpectedly high. Table 2 illustrates that surprising increases in notched Izod impact strength were also obtained.

Table 2

are blended with relatively rigid polyesters and the flexural modulus is measured. The flexible pόlyetherester is Polymer X, and the relatively rigid polyester is polyethylene terephthalate having an I.V. of 0.70.

Example 4. Flexible polyetheresters are blended with relatively rigid polyesters as indicated in the following table, and the flexural modulus is measured. The flexible polyetherester is Polymer X and the relatively rigid polyester is a polyester of terephthalic acid, 68 mol % 1,4—cyclohexanedimethanol and 32 mol % ethylene glycol having an I.V. of 0.75.

Example 5. Flexible polyetheresters are blended with relatively rigid polyesters as shown in the following table and properties are measured. The flexible polyetherester is the same as Polymer X, except the trimellitic anhydride is omitted. The relatively rigid polyester is Polymer Y. The data shown in parentheses is the predicted value for comparison, showing the modulus of the blends according to this invention being higher than expected.

% Flexible % Notched Izod

Polyether— Polymer Joules/ ester Y Flexural Modulus* ft-lb/in. Meter

100 0 18,000 ( 18,000) 10.2 545

1,265 ( 1,265)

39,000 ( 32,000) 12.3 657

2,742 ( 2,250)

100,000 ( 52,000) 20.6 1,100

7,031 ( 3,656)

155,000 ( 80,000) 10,898 ( 5,625)

240,000 (150,000) 16,875 ( 10,546) 260,000 (260,000) 18,280 ( 18,280) * In each instance, upper numbers are in psi and lower

2 numbers are in Kg/cm .

Example 6. Flexible polyetheresters are blended with relatively rigid polyesters as shown in the following table and properties are measured. The flexible polyetherester is the same as Polymer X, except the concentration of 1,4—cyclohexanedimethanol is 70 mol % and the concentration of the poly(oxytetramethylene glycol) is 30 mol %. The relatively rigid polyester is Polyester Y. % Flexible % Flexural Modulus* Notched Izod Polyether— Polymer ( ) Indicates Joules/ ester Y Predicted Value ft-lb/in. Meter

150 0 9,500 ( 9,950) 7.3 390 668 ( 668) 80 20 25,000 ( 18,000) 11.6 620 1,758 ( 1,265) 60 40 70,000 ( 36,500) 12.9 689 4,922 ( 2,566) 40 60 148,000 ( 70,000) 10,405 ( 4,922) 20 80 215,000 (135,000) 15,117 ( 9,492) 0 100 260,000 (260,000) 18,280 ( 18,280)

*In each instance, upper numbers are in psi and lower

2 numbers are in Kg/cm .

Example 7 Example 6 is repeated, except the concentration of 1,4—cyclohexanedimethanol is 80 mol % and the concentration of poly(oxytetramethylene glycol) is 20 mol %.

% Flexible % Flexural Modulus* Notched Izod Polyether— Polymer ( ) Indicates Joules/ ester Y Predicted Value ft-lb/in. Meter

100 0 23,500 ( 23,500) 11.2 598 1,652 ( 1,652)

80 20 44,500 ( 37,000) 13.8 .737

3,128 ( 2,601)

60 40 88,000 ( 60,500) 23.9 1,276

6,187 ( 4,254)

40 60 160,000 ( 99,000)

11,250 ( 6,960)

20 80 230,000 (170,000)

16,171 ( 11,952)

0 100 260,000 (260,000)

18,280 ( 18,280)

*In each instance, upper numbers are in psi and lower

2 numbers are in Kg/cm . Example 8. Additional blends are made as in the previous examples, using Polymer X and Polymer Z. In this example, the polyester is made by the direct esterification of terephthalic acid rather than using dimethyl terephthalate (I.V. = 0.75).

% Flexible % Flexural Modulus* Notched Izod Polyether- Polymer ( ) Indicates Joules/ ester Y Predicted Value ft-lb in. Meter

16,171 ( 6,750)

20 80 275,000 (170,000) 19,335 ( 11,952) 0 100 290,000 (290,000) 20,390 ( 20,390)

*In each instance, upper numbers are in psi and lower

2 numbers are in Kg/cm .

Example 9. Example 8 is repeated, except the relatively rigid polyester is derived from 100 mol % terephthalic acid, 80 mol % 1,4—butanediol and 20 mol % 1,4—cyclohex¬ anedimethanol (I.V. = 0.85). % Flexible % Flexural Modulus* Notched Izod Polyether— Polymer ( ) Indicates Joules/ ester Y Predicted Value ft—lb/in. Meter 100 0 19,000 ( 19,000) 9.6 513

1,335 ( 1,335)

80 20 44,000 ( 34,100) 13.7 732

3,094 ( 2,398)

60 40 122,000 ( 56,200) 18.2 972

8,578 ( 3,951) 40 60 231,000 ( 97,000)

16,242 ( 6,820)

20 80 278,000 (172,000)

19,546 ( 12,093)

0 100 300,000 (300,000)

21,093 ( 21,093) *In each instance, upper numbers are in psi and lower

2 numbers are in Kg/cm .

Example 10. Each of the polymer blends described above is extruded into a sheet, provided with a paint layer by roll coating, and allowed to dry. The sheet is then provided with a suitable adhesive on the side opposite the paint and bonded to a panel by a thermoforming technique. During the thermoforming operation, the sheet is first heated to a soft state and air pressure differential used to draw the soft sheet around a support panel of polypropylene. The experiments are repeated, using the in-mσld processing technique described hereinbefore. In these experiments, it is seen that the stiffness of the carrier sheet is compatible with that of the support panel. The impact resistance (values of which are set forth in the above examples) is adequate for uses such as automobile bumpers where crack resistance, indentation resistance and energy absorption is important.

Conventional additives may be used in either component or the blend. Such additives include colorants, stabilizers, plasticizers, flame retardants, adhesive promoters, etc.

As used herein, the inherent viscosity (I.V.) is measured at 25°C using 0.50 gram of copolyester per 100 ml of a solvent consisting of 60 percent by weight phenol and 40 percent by weight tetrachloroethane. The Flexural Modulus and notched Izod impact strength tests used herein are in accordance with ASTM D790 and ASTM D256 respectively.

Unless otherwise specified, all parts, percentages, ratios, etc. are by weight.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

Claims

We claim:

l. A composition comprising a blend of a flexible poly(etherester) with a more rigid polyester, the blend characterized as having

(A) 98-2 weight % of a flexible poly(etherester) having an I.V. of 0.8—1.5 and recurring units from

(1) a dicarboxylic acid component consisting essentially of 1,4—cyclo¬ hexanedicarboxylic acid having a trans isomer content of at least 70%, (2) a glycol component consisting essentially of

(a) 95 to 65 mol % 1,4-cyclohexane- dimethanol, and

(b) 5 to 35 mol % poly(oxytetra— methylene) glycol having a molecular weight of 500 to 1100, and

(B) 2-98 weight % of a relatively rigid polyester having recurring units from 80—100 mol % terephthalic acid and at least one aliphatic or cycloaliphatic glycol having 2—12 carbon atoms, said polyester having an I.V. of 0.5-1.0, the blend having improved stiffness and notched Izod impact strength when compared to the poly(etherester) alone.

2. Composition according to Claim 1 characterized as having an amount up to 1.5 mol % of a polyfunctional branching agent having at least 3 carboxyl or hydroxyl groups.

3. Composition according to Claim 1 characterized by said rigid polyester consisting essentially of recurring units of terephthalic acid, and recurring units from at least one of the glycols selected from ethylene glycol, 1,4—butanediol, and 1,4-cyclohexanedimethanol.

4. A composition comprising a blend of a flexible poly(etherester) with a more rigid polyester, the blend characterized as having

(A) 98-60 weight % of a flexible poly(etherester) having an I.V. of 0.8—1.5 and recurring units from

(1) a dicarboxylic acid component consisting essentially of

1,4—cyclohexanedicarboxylic acid having a trans isomer content of at least 70%,

(2) a glycol component consisting essentially of (a) 95 to 65 mol % 1,4—cyclohexane¬ dimethanol, and (b) 5 to 35 mol % poly(oxytetra— methylene) glycol having a molecular weight of 900 to 1050, and

(B) 2-40 weight % of a relatively rigid polyester consists essentially of recurring units of terephthalic acid, and recurring units from at least one of the glycols selected from ethylene glycol,

1,4—butanediol, and 1,4-cyclohexanedi— methanol. the blends having improved stiffness and notched Izod impact strength when compared to the poly(ether—ester) alone.

5. A thermoformed article characterized by having the composition of Claim 1.

6. A thermoformed article characterized by having the composition of Claim 4.

7. An injection molded article characterized as the composition of Claim 1.

8. An injection molded article characterized as the composition of Claim 4.

9. Sheet material adapted to be adhered to a support panel comprising a carrier sheet having a coating on one side thereof, said carrier sheet characterized as comprising the composition of Claim 1.

10. A composition comprising a blend of a flexible poly(etherester) with a more rigid polyester, the blend characterized as having (A) 98-60 weight % of a flexible poly(etherester) having an I.V. of 0.8—1.5 and recurring units from (1) a dicarboxylic acid component consisting essentially of 1,4—cyclohexanedicarboxylic acid having a trans isomer content of at least 70%, (2) a glycol component consisting essentially of

(a) 95 to 65 mol % 1,4—cyclohexane¬ dimethanol, and

(b) 5 to 35 mol % poly(oxytet a— methylene) glycol having a molecular weight of 900 to 1050, and (B) 2-40 weight % of a relatively rigid polyester consists essentially of recurring units of terephthalic acid, and recurring units from at least one of the glycols selected from ethylene glycol,

1,4—butanediol, and 1,4—cyclohexane¬ dimethanol, the blends having improved stiffness and notched Izod impact strength when compared to the poly(ether—ester) alone.

11. A substrate characterized as having sheet material according to Claim 9 bonded thereto.

12. A composition comprising a blend of a flexible poly(etherester) with a more rigid polyester, the blend characterized as having (A) 98-60 weight % of a flexible poly(etherester) having an I.V. of 0.8—1.5 and recurring units from

(1) a dicarboxylic acid component consisting essentially of 1,4—cyclohexanedicarboxylic acid having a trans isomer content of at least 70%, (2) a glycol component consisting essentially of

(a) 95 to 65 mol % 1,4—cyclohexane¬ dimethanol, and

(b) 5 to 35 mol % poly(oxytetra— methylene) glycol having a molecular weight of 900 to 1050, and (B) 2—40 weight % of a relatively rigid polyester consists essentially of recurring units of terephthalic acid, and recurring units from at least one of the glycols selected from ethylene glycol, 1,4—butanediol, and 1,4—cyclohexane¬ dimethanol, the blends having improved stiffness and notched Izod impact strength when compared to the poly(ether—ester) alone.