CH650392A5 - FIREPROOF DISHWARE BASED ON A SHAPED, MODIFIED HOMO OR COPOLYESTER, IF ANY. - Google Patents

Description

The polyesters usable for the present invention can also be chemically modified in various ways, e.g. by incorporating monofunctional reactants such as benzoic acid or trifunctional or higher functional reactants such as trimesic acid or cyanuric acid chloride in the polyester. The benzene rings in these polyesters are preferably unsubstituted, but can also be substituted by non-interfering substituents, for example by halogen, such as chlorine or bromine, lower alkoxy, such as methoxy, and lower alkyl, such as methyl.

The polyesters which can be used for the present invention can be used together with various fillers, the types and amounts of which do not significantly affect the desired properties. Examples of suitable fillers are glass fibers, polytetrafluoroethylene, pigments and polyimides.

The invention is illustrated in more detail in the following examples, in which all parts and percentages are by weight unless otherwise stated. These examples relate to certain embodiments; they are intended to serve as a guide to those skilled in the art for practicing the invention and are to be considered the best mode for carrying out the invention.

example 1

250 g of a mixture of 40% o-terphenyl and 60% m-terphenyl are introduced into a four-necked round bottom flask equipped with a stirrer, nitrogen inlet, thermometer and a distillation attachment connected to a condenser. The distillation attachment is wrapped on the outside with an electrical resistance heating wire so that it can be heated. A heating jacket is used to heat the flask and its contents. The contents of the flask are melted by heating to approximately 60 ° C,

after which 68 g of p-acetoxybenzoic acid are added with stirring. All condensation is carried out with stirring and slowly passing nitrogen through the flask to maintain a non-oxidizing atmosphere. The still is heated to approximately 120 ° C and the mixture in the flask to approximately 340 ° C, with the polyester beginning to precipitate at approximately 300 ° C. Then the temperature of the still is raised to about 180 ° C to prevent the distillate from flowing back and / or solidifying in the still; the mixture in the flask is kept at about 340 ° C for about 12 hours. A total of 25.5 g of distillate is collected, which consists mainly of acetic acid, while the rest consists mainly of terphenyl, the liquid heat transfer medium. It is observed that 25 g of this distillate within 35 min after the

= 3 to 600, preferably 20 to 200, the carbonyl groups of the unit of the formula IX or X are bonded to the oxy groups of a unit of the formula IX or XI and the oxy groups of the unit of the formula IX or XI to the carbonyl groups of a unit of the Formula IX or X are bound.

The preferred copolyesters contain periodically recurring units of the formula:

XII

When the temperature reaches 340 ° C, this indicates that the polymerization is almost complete within this time.

The resulting mixture is cooled to 80 ° C, whereby it becomes completely viscous. Approximately 200 ml of acetone are slowly added and the mixture is filtered to recover the precipitated polyester. The polyester is extracted with acetone in a Soxleth extractor overnight to remove any residual terphenyl heat transfer agent and then dried in vacuo at 110 ° C for 3 hours. A yield of 43 g (96% of theory) of p-oxy-benzoyl polyester powder is obtained.

The product was infusible and showed a weight loss of only 0.83% per 30 hours when kept at 400 ° C in air. Thermal differential analysis showed an endothermic reaction at 329 to 343 ° C during heating with a peak at 336 ° C and a corresponding exothermic reaction during cooling as evidence of a reversible crystalline transition. This reversible crystalline-35 line transition was also evidenced by a noticeable change that occurred in the X-ray powder scatter image when the product was heated to approximately 340 ° C, with the original image returning after cooling.

In the X-ray powder scatter image of the product at room temperature, using monochromatic copper-K alpha rays, the large number and the sharpness of the scatter lines indicate that the polyester is highly crystalline.

45 The use of the liquid heat transfer medium is essential for the method used. The liquid must be inert, i.e. it must be non-reactive with the p-acetoxybenzoic acid monomer and its condensation products under the conditions used. It must also be such a high-boiling liquid and, under the conditions used, have a boiling point which is at least as high as the highest temperature to which the reaction mixture is heated and expediently somewhat higher so that reflux can be avoided. Of course, the heat transfer medium need not be liquid at room temperature, but it should preferably have a melting point below that of the monomer (approximately 180 ° C). A wide variety of materials have been found to be useful heat transfer agents, including, for example, o-terphenyl, m-terphenyl, p-terphenyl and mixtures of two or three thereof as used in this example; partially hydrogenated terphenyls, such as are commercially available under the brand name Therminol® 66; and a eutectic mixture of 73.5% diphenyl oxide 65 and 26.5% diphenyl such as the heat transfer medium commercially available as Dowterm® A. Other suitable heat transfer agents are diphenoxybiphenyls and mixtures thereof, as disclosed in U.S. Patent No. 3,406,207.

650 392

6

Example 2

This example illustrates the synthesis of a copolyester which can be used according to the invention.

The following amounts of the following ingredients are combined as indicated.

Substance name

component

Amount of grams

Mol

A

p-hydroxybenzoic acid

138

1

B

Phenylacetate

170

1.25

C.

Therminol 77

500

-

D

Diphenyl terephthalate

318

1

E

Hydrogen chloride

-

-

F

Hydroquinone

111

1.01

G

Therminol 77

500

-

Parts and 8010 parts of distillate are obtained. The contents of the reaction vessel are removed, cooled and ground to a particle size of 0.84-0.42 mm (20-40 mesh, U.S. Standard Sieve Series). The resin produced has a molecular weight in the range of 5,000-20,000, with the average being approximately in the middle of this range. The product is estimated to be approximately 50% crystalline.

The resin is kept under vacuum, for example 8 hours at an elevated temperature under an absolute pressure of about 133 mbar, and then gives a granular powder.

Example 4

The following amounts of the following ingredients are combined as indicated

Substances A to D are introduced into a four-necked round bottom flask equipped with a thermometer, stirrer, combined inlet for nitrogen and HCl and an outlet connected to a cooler. Nitrogen is slowly introduced through the inlet. The flask and its contents are heated to 180 ° C, whereupon HCl is bubbled through the reaction mixture. The outlet temperature is maintained at 110-120 ° C by external heating during the p-hydroxy-benzoic acid-phenylacetate transesterification reaction. 30th

The contents of the flask are stirred at 180 ° C for 6 h, after which the HCl supply is switched off, the outlet head temperature is increased to 180-190 ° C and the mixture is stirred at 220 ° C for 3.5 h. Substance F is then added and the temperature is gradually increased from 220 ° C to 320 ° C over the course of 10 hours (10 ° C / h). Stirring is continued at 320 ° C for 16 hours and then at 340 ° C for a further 3 hours, forming a slurry. The total amount of distillate, consisting of phenol, acetic acid and phenylacetate, is 384 g. Substance G is added and the reaction mixture is allowed to cool to 40-70 ° C. Then acetone (750 ml) is added, the slurry is filtered and the solids are extracted with acetone in a Soxleth apparatus to remove substances C and G. The solids are dried in vacuo at 110 ° C. overnight, after which the 45 resulting copolyester (320 g, 89.2% of theory) is obtained as a granular powder.

The oxybenzoyl polyesters, which are generally discussed further above and are specifically illustrated in Examples 1 to 5, can be formed into the cookware according to the invention by customary processes. Common additives intended for specific purposes can be introduced before molding. US Pat. Nos. 3,884,876 and 3,980,749 disclose molding processes for oxybenzoyl polyesters which could be adapted to the manufacture of the kitchenware.

15

Substance name

component

Amount of grams

Mol

A

Terephthalic acid

291

1.75

2® B

p-hydroxybenzoic acid

483

3.50

C.

p, p'-biphenol

325

1.75

D

Acetic anhydride

755

7.40

The substances A to D are heated to 145 ° C. and kept under reflux overnight. The reflux condenser is removed and a distillation head is attached. The mixture is heated to 300 ° C with stirring at a rate of 20 ° C / h, after which the reactor is drained. At this point, approximately 92-94% of the theoretical amount of acetic acid had been collected. The prepolymer is ground and further treated using a temperature of approximately 250-350 ° C as in Example 3.

Example 5

substance

component

Quantity designation

Grams of mol

A

p-hydroxybezoic acid

276 (2.00)

B

Terephthaloyl chloride

203 1.0

C.

Trimesic acid

8.4 0.040

D

Therminol 66

1274

E

p, p'-biphenol

186 1.0

F

Acetic anhydride

224.6 2.2

Example 3

518 parts of isophthalic acid, 1557 parts of terephthalic acid, 5175 parts of p-hydroxybenzoic acid, 6885 parts of acetic anhydride 6 'and 2325 parts of p, p' bisphenol are mixed together and refluxed for 17 hours at a temperature of approximately 180 ° C, after which the reflux condenser is passed through a The distillation head is replaced and the temperature is increased to 345 ° C in the course of 1 x h. The reaction mixture is stirred throughout the heating, being particularly vigorously mixed as the temperature rises to 345 ° C. The yield of polymer is 8 020

The substances A to D are heated to 130 ° C. and kept at this temperature for 1 h. The reaction is exothermic and care must be taken to keep the temperature at 130 ° C. The feed is then heated to 155 ° C for 1 hour and then to 180 ° C for 4 hours. After the mixture has cooled to 150 ° C., substance E is added, the temperature being reduced further to 140 ° C. This mixture is heated to reflux at 155 ° C for 1 h; then the reflux condenser is replaced by a distillation column. During the distilling off of the acetic acid formed, the contents of the reactor are heated to 330 ° C. and kept at this temperature for 3 hours. The suspended polymer is cooled to 250 ° C and the mixture is filtered. The solid material is treated with trichlorethylene to remove the heat transfer fluid. The dried powder is kept under vacuum as in Example 3.

In order to demonstrate the unique suitability of oxybenzoyl polyesters for the production of oven cookware, tests were carried out with various plastic cooking containers,

7

650392

such as bowls, trays, etc., which were made from oxy-benzoyl polyesters, polysulfone, polybutylene terephthalate, polypropylene, polycarbonate and a thermosetting polyester.

Example 6

Empty («No Load») test in a thermal (electrical) furnace

The plastic item was placed in a glass container on a tray 14 cm above the bottom of the oven. The oven temperature was set and the oven was allowed to warm from room temperature. The plastic article stayed in the oven for vh or shorter if it failed earlier.

The following results were found. A cup cut out from a baking mold for several individual baked goods, made from a heat-curing polyester resin, developed an odor within 15 minutes and began to smoke after 30 minutes at an oven temperature of 210.degree. A 5 cm strip cut out of a bacon tray made from a polysulphone resin softened in 15 minutes and was completely deformed at an oven temperature of 210 ° C. A 5 cm strip cut out of a roasting sheet made of a polycarbonate resin softened and was completely deformed in 10 minutes at an oven temperature of 210 ° C. A bowl made of a polypropylene resin melted to flatten within 10 minutes at an oven temperature of 210 ° C. A casserole made of polybutylene terephthalate started smoking after 5 minutes and developed a noticeable smell, but it became hot in 30 minutes. not deformed at a temperature of 210 ° C. A bowl, made according to the invention, from an oxybenzoyl polyester showed no sign of damage after 1 h at an oven temperature of 260 ° C.

Example 7

Microwave oven - empty test

When performing this test, the plastic article was placed in the center of the microwave oven directly on the glass plate. The item was heated at full strength for 20 minutes or, if previously failed, for a shorter time.

The following results were found. A cup cut out of a baking mold for individual baked goods, made from a filled, thermosetting polyester, developed a slight smell within 17 minutes, but showed no other signs of damage. A 23 cm polypropylene baking sheet showed no damage other than softening on the floor where the edge touched the hot glass plate. Holes were burned in the side and bottom within 11 minutes into a cup cut out of a baking pan for individual pastries made of polybutylene terephthalate. A grill rack made of polycarbonate resin showed a deformed location of 2.54 cm in diameter in the middle of the grill. A bacon roaster made of polysulfone "udel" resin showed no damage. A bowl of clear sulfone "udel" resin showed discoloration on the bottom. A bowl made of an oxybenzoyl polyester showed no damage of any kind.

Example 8

Oil resistance — microwave oven test

When performing this test, a layer of Wesson oil was poured into the plastic container. The jar was placed in the middle of the glass plate in the microwave oven. After various dwell times with high force, the vessel was removed and examined.

The following results were found. A

Bowl made of a polypropylene resin showed streaks below the oil line within 6 min (strongly after 9 min). After washing, it turned out to be bubbles that peeled off easily as fibrous strands. A bowl made of a polysulfone resin showed clearly visible streaks below the oil within 6 minutes. After washing, bubbles, cracks and a "burn" stain were observed on the bottom of the bowl. In the case of a cup cut out of a baking mold for individual baked goods, made of polybutylene terephthalate, the connection between the side wall and the base burst after 5 minutes of exposure, so that oil flowed out. A slight darkening below the oil resisted soap and water. A bowl made of an oxybenzoyl polyester showed no noticeable damage after 20 minutes. The bowl could be washed clean without leaving any stains.

Example 9

Freeze-thaw heating test in the oven

When this test was carried out, the plastic containers were charged with approximately 100 g of chilli (canned chili meat from the trade) and frozen in the freezer compartment of the refrigerator overnight. Then the plastic containers were placed on a tray in an oven heated to 218 ° C and left therein until the contents boiled with blistering. If the container failed, it was removed earlier.

The following results were found. A bowl made of a polypropylene resin melted to the level of the food after 8 minutes without it being thawed. A bowl made of a polysulfone resin had a deformation on the spout after 27 minutes; after 33 minutes the bowl was soft and deformed. The food was warm, but not hot. The bowl could be cleaned spotlessly. A frying pan made of polybutylene terephthalate had warped sides after 12 minutes. After 20 minutes the item was completely out of shape and the food was not warm. The pan was easy to clean, but showed slight stains. In a frying pan made of a thermosetting polyester, the food took 35 minutes to get hot. The pan was difficult to clean and slightly stained. A bowl made of an oxybenzoyl polyester showed no damage after boiling the food for 40 minutes. It was easy to clean and showed no stains.

Example 10

Stain and smell test (barbecue sauce)

When performing this test, barbecue sauce (Kraft) was placed in a 12.7 mm high layer on the bottom of the plastic container. The container for Vi h was then placed in an oven preheated to 204 ° C. After this time, the sauce was thick, dark, and crusted. After cooling, the container was washed with soap and water using a "Dobie" bottle. The container was examined for a stain line and was rated as stained if the stains could not be removed by further washing for 15 minutes. The container was then returned to the oven for 15 minutes, after which it was removed and its smell was found to be hot. Every unusual smell was noted.

The following results were found. A cup cut out from a baking mold for individual baked goods, made from a heat-curing polyester, showed a strong yellow discoloration. There was a residual smell of barbecue sauce. One from a baking pan for individual pastries, made from polybutylene terephthalate, from 5

10th

15

20th

25th

30th

35

40

45

50

55

60

65

650392

cut cup showed strong yellow discoloration. An unidentified residual odor was identified that could be from polymers. A bowl made of polysulfone resin developed a faint smell. A bowl of oxybenzoyl polyester showed no stains or smell.

The polyester articles used in the tests of Examples 6-10 were made from the polyester of Example 3.

Similar tests with articles from the polyesters of the; Examples 1, 2, 4 and 5 gave comparable excellent results.

B

Claims (5)

■ 00 "O" 00 'It is easy to see which of these substances can also deliver the units of the formulas VII to XII. Examples of compounds that provide units of formula IV are 6-hydroxy-l-naphthoic acid, 5-acetoxy-l-naphthoic acid and 5-hydroxy-l-naphthoic acid phenyl ester. Compounds which provide units of formula V are e.g. 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid and 2,6-naphthalenedicarboxylic acid. The diphenyl esters or diacid chlorides of these acids can also be used. Examples of compounds that provide units of Formula VI are 1,4-dihydroxynaphthalene, 2,6-diace-toxynaphthalene and 1,5-dihydroxynaphthalene. In the practice of the invention, plastics based on oxybenzoyl polyesters are particularly preferred. The oxybenzoyl polyesters which can be used according to the invention are generally those having periodically recurring units of the formula: 20 25 • 0 -CO VII Jp XI a where p is an integer from 3 to 600. A preferred class of oxybenzoyl polyesters corresponds to the formula: corresponding to where X is O, S, -CO-, -NH- or -SO2- and n is 0 or 1, the sum of the integers p + q + r + s + t + u in the existing units is 3 to 800. Combinations of the above units result from combining the carbonyl groups of the formulas I, II, IV and V with the oxy groups of the formulas I, III, IV and VI. In the most general combination, all units of the above formulas can be present in a single copolymer. The simplest embodiment would be homopolyesters of units I or IV. Other combinations are e.g. Copolyesters from units II and III, II and IV, III and V, V and VI and I and IV. The carbonyl and / or oxy groups on the benzene nucleus are preferably in the p-position (1,4-position) to one another. But they can also be in the ortho position (1,2 position) to each other. In the naphthalene unit, the most desirable positions of the carbonyl or oxy groups are the 1,4, 1,5 and 2,6 positions. But they can also be in the ortho position to each other. The symbols p, q, r, s, t and u mean integers and indicate the number of units present in the polymer. The total (p + q + r + s + t + u) varies from 30 to 800, and the possible ratio of q / r, q / u, t / r, t / u, q + t / r + u and t / r + u can be between 10/11 and 10/10 and is preferably 10/10. Examples of compounds from which the units of the formula I can be obtained are p-hydroxybenzoic acid, p-hydroxybenzoic acid phenyl ester, p-acetoxybenzoic acid and p-acetoxybenzoic acid isobutyl ester. The units of formula II are e.g. derived from terephthalic acid, isophthalic acid, terephthalic acid diphenyl ester, isophthalic acid di-ethyl ester, methyl terephthalic acid and the isobutyl half-ester of terephthalic acid. The units of formula III result e.g. from p, p'-bisphenol, p, p'-oxybisphenol, 4,4'-dihydroxybenzophenone, resorcinol and hydroquinone. VIII wherein R1 is benzoyl, lower alkanoyl or preferably hydrogen, R2 is hydrogen, benzyl, lower alkyl or preferably phenyl and p is an integer from 3 to 600, preferably 30 to 200. These values of p correspond to a molecular weight of 1000 to 72,000, preferably 3500 to 25,000. The synthesis of these polyesters is 45 in detail in US Patent Application No. 619,577 dated March 1, 1967, entitled "Polyesters Based on Hydroxybenzoic Acids »that has been dropped. This application is referred to in U.S. Patent No. 3,668,300. 50 Another preferred class of oxybenzoyl polyesters are copolyesters with periodically repeating units of the formulas: • 0 -0- ° ° IX -Ip 65 ■ OC- -0CO 650392 PATENT CLAIMS 1. Refractory dishes based on a shaped, optionally modified homo- or copolyester characterized in that the polyester contains periodically recurring units which one or more of the formulas: III r IV s 1 J, VII IX 2nd 15 correspond, where X is O, S, -CO-, -NH- or -SO2- and n is 0 or 1, the sum of the integer p + q + r + s + t + u in the available units 3 to 800. 2. Dishes according to claim 1, characterized in that the quotients q / r, q / u, t / r, t / u, q + t / r, q + t / r + u and t / t + u 10 to 11/10, preferably 10/10. 3rd 650392 contains, or consists of such units, wherein X is -O-or -SO2-, m = 0 or 1, n = 0 or 1, q: r = 10:15 to 15:10, p: q = 1: 100 to 100: 1, p + q + r = 3 to 600, the carbonyl groups of the unit of the formula IX or X are bonded to the oxy groups of a unit of the formula IX or XI and the oxy groups of the unit of the formula IX or XI are bonded to the carbonyl groups of the unit of the formula IX or X, preferably m and / or n = 0 and / or p + q + r = 20 to 100. 6. Tableware according to claim 1, characterized in that the polyester periodically recurring units of the formula: CO-O XII contains. units that use one or more of the formulas: 25th As is known, certain plastic materials have found application in the field of refractory dishes. For example, polymethylpentene was used for the injection molding of bowls and the like. The like. Used that can serve for the preparation 30 of food. Polysulfone has also been used for food handling. However, no satisfactory material has yet been found that is useful within the wide range of conditions and requirements encountered in fire-resistant dishes that can be used in both thermal ovens and microwave ovens. In addition to the obvious necessity that the material has to withstand the temperatures of the heat sources used for cooking, the material also requires a unique combination of other properties if the fireproof dishes made from it are to be suitable for the preparation of food. The material must have good electrical properties. Severe thermal shocks must be tolerated so that the refractory dishes made from them can be brought from extremely cold to high temperatures in a relatively short time. The material must have good hardness and impact strength, as well as high tensile strength and bending strength. It must also be resistant to boiling water and the detrimental effects of immersion in surfactant solutions. With regard to the properties associated with the food, the material must give the refractory dishes produced from it insensitivity to the formation of stains by a wide variety of foods. It must provide a surface that has good antistatic properties and from which the food can easily detach. It must not develop or release volatile substances and it must not contain any extractable components. In addition to all of the above, the articles made from the material must have a pleasing appearance. The refractory tableware based on a shaped, possibly modified homo- or copolyester, in particular an oxybenzoyl polyester, meets the strict requirements of the cookware market. These polyesters contain periodically recurring inputs .0 ^ / 7 - r>> (X) nX ^ - ^ CQ- 11 ■ ° ~ # y (x) n ^ y 0 - m IV V VI u 650392 VII IX -jp 3. Tableware according to claim 1, characterized in that the polyester periodically recurring units of the formula 25: contains or consists of such units, where p is preferably an integer from 3 to 600. 4. Tableware according to claim 1, characterized in that the polyester of the formula: U V VI 40 R .OR ' VIII J 45 where R1 is hydrogen, benzoyl or lower alkanoyl, R2 is hydrogen, benzyl, lower alkyl or phenyl and p is an integer from 3 to 600, preferably 30 to 200. 5. Tableware according to claim 1, characterized in that the polyester periodically recurring units of the formulas: .0— 5 650392 where X is -O- or -SO2-, m = 0 or 1, n = 0 or 1, q: r = 10:15 to 15:10, p: q = 1: 100 to 100: 1 is, p + q + r The synthesis of these polyesters is described in detail in US Patent Application No. 828,484 entitled "p-Oxybenzoyl Copolyesters".