HK1073143B - Use for the oleo-repellent paper sizing of carboxylic perfluoropolyethers - Google Patents

Description

Use of carboxyl-containing perfluoropolyethers for sizing oil-repellent papers

Description of the Industrial invention in the name of SOLVAY SOLEX S.p.A. (Italy, headquarters in Milan, Via Turati, 12).

Technical Field

The invention relates to the use of perfluoropolyethers having carboxylic end groups for sizing oilproof paper.

Background

Greaseproof paper and paper products are mainly used for packaging fats, such as butter or margarine, products like coffee and chocolate, and foods with a high fat content, such as meat, chips (chips), burgers, popcorn, foods cooked in a microwave oven, cat or dog crisps (crisps) and pet foods in general.

Oil repellency is generally evaluated by Kit Test (TAPPI 557 method) based on the resistance of a drop of hydrocarbon or hydrocarbon mixture having a gradually decreasing surface tension to sized paper. However, the oil repellency values obtained with the kit test are the only indices of the surface activity of the additives, which are often poorly correlated with the authenticity performance in terms of the protective barrier of the paper against oils and fats, both under the usual conditions of use where the food has a long contact time with the paper package at room temperature and under the more severe temperatures and conditions that lead to a reduction or impairment of the oil repellency of the package (such as paper packages heated in ovens, contact with hot food and mechanical stresses caused by the folding system that obtains the package, and stresses during their use that cause creasing).

It has been found that a high test value of the kit is not always of interest for evaluating oil repellency under practical conditions of paper use. Thus, users of grease resistant paper utilize a series of more stringent performance tests than the kit test and tests that are more representative of actual resistance to fats and oils (behaviour).

The most common tests used by the end user are as follows:

Ralstonthe Purina fold (harvested) assay (RP-2 fold assay);

performing an oleic acid test;

the Eukanuba test;

turpentine test (TAPPI T-441-om);

fatty acid test.

See the detailed description made in the examples.

For The Sizing of oil-repellent papers, The use of phosphates with perfluoroalkyl-type segments ("Organofluorine Chemicals and Industrial Applications", page 231. 232, Banks, R.E. edition, 1979), The use of phosphates and carboxylates with perfluoroalkyl-type segments and thioether bonds ("Howell R.D.", Sizing with fluorine-Chemicals ", TAPPI Sizing Short Cour, April 14-16, 1997, Atlanta; Deisenroth E.et al, The design of a new grease-repellent fluorine for The Paper industry, Surface Coating International (9), page 440, 1998) and The use of polymers with perfluoroalkyl segments (Chad R.M. et al," Sizing of Paper ", page 2, Ed. TAPPIPRESS, 19890) are known, good results are obtained using The test kit, good results are not always obtained using the more rigorous tests described above, which are commonly used by end users.

Compounds which satisfy the above tests (such as the oleic acid test and the Ralston test) are known. See, e.g., european patent application No.02.014.155, which describes aqueous polyurethane (polyurethane) compositions containing perfluoropolyether structures and their use in oil-repellent paper sizing. The polyurethanes described, which are capable of imparting oil repellency to paper and which satisfy the tests described above, are generally used for the wet-end treatment of cellulose pulp or for the surface treatment of the size press, preferably for the wet-end, since better properties can be obtained. However, papers meeting the above tests require high amounts of the polyurethane.

In addition, other compounds are known which satisfy the above tests (such as the oleic test and the Ralston test), which are based on phosphoric esters containing perfluoropolyether chains, for wet end treatment and size press treatment. However, these two treatments require different formulations. In addition, the amount used to obtain good oil repellency is high. See e.g. european patent applications EP 03000384, EP 03000385.

Among the various possible processes, the treatment of the wet end of paper with fluorinated products is one which generally gives the best oil-repellent properties, since in this case the result is that every single cellulose fibre is treated with a fluorinated product. The external sizing of fluorinated products is generally limited to the surface layer of the paper, with the subsequent possibility that the folding or calendering process will reduce its oil repellency, since these processes alter the surface layer of the paper and make oil penetration possible. The most well known surface treatment methods are those that require the application of impregnation by size press to oil resistant products.

In wet end applications where the oil-repellent compound is added to a very dilute suspension of cellulose fibres in an amount of 0.2-3% by weight, it is important to obtain efficient product retention on the fibres. "retention" is defined as the ratio of the amount of oil-repellent compound that remains bound to the paper to the amount of product that flows back into the cellulosic fiber suspension. Poor retention means that a portion of the product is lost to the filter water after the paper is formed. Therefore, high compound retention is desirable because known compounds containing perfluoroalkyl-containing segments that impart oil repellency are very expensive.

The need was therefore felt to obtain a compound for sizing oilproof paper having the following combination of properties:

-the ability to impart oil repellency to paper, which passes the most stringent performance tests (such as those described above) for end-user bulk (wet end) and surface applications.

High retention in wet end processing with subsequent results in little or no product loss.

The applicant has surprisingly and unexpectedly found compounds capable of satisfying the above requirements.

Disclosure of Invention

One object of the present invention is the use of a perfluoropolyether having the structure:

T-O-R_f-T (I)

wherein

-T＝-CF₂-COOH or-CF₂CF₂-COOH；

-R_fIs a (per) fluoropolyoxyalkylene chain having a number average molecular weight in the range of 500-10000, consisting of one or more recurring units, statistically distributed along the chain, having the following structure:

(CFXO)，(CF₂CF₂O)，(CF₂CF₂CF₂O)，(CF₂CF₂CF₂CF₂O)，

(CR₄R₅CF₂CF₂O)，(CF(CF₃)CF₂O)，(CF₂CF(CF₃)O)，

wherein X ═ F, CF₃；R₄And R₅Identical or different from each other, selected from H, Cl, or a perfluoroalkyl group having 1 to 4 carbon atoms.

In particular, the following fluoropolyethers R_fAs preferred:

(A)-(CF₂CF(CF₃)O)_a(CFYO)_b-

wherein Y is F or CF₃(ii) a a and b are integers such that the molecular weight is within the above range; a/b is between 10 and 100;

or the repeating units represented in (a) may be linked in the following structure:

-(CF₂CF(CF₃)O)_a(CFYO)_b-CF₂(R’_f)CF₂-O-(CF₂CF(CF₃)O)_a(CFYO)_b-

wherein R'_fIs a fluoroalkylene group having 1 to 4 carbon atoms;

(B)-(CF₂CF₂O)_c(CF₂O)_d(CF₂(CF₂)_zO)_h-

wherein c, d and h are integers such that the molecular weight is within the above range, and h may also be 0; c/d is between 0.1 and 10; h/(c + d) is between 0 and 0.05; z is 2 or 3;

(C)-(CF₂CF(CF₃)O)_e(CF₂CF₂O_f(CFYO)_g-

wherein Y is F or CF₃(ii) a e, f, g are integers such that the molecular weight is within the above range; e/(f + g) is between 0.1 and 10, f/g is between 2 and 10;

(D)-(CF₂(CF₂)_zO)_s-

wherein s is an integer giving the above molecular weight and z has the already defined meaning;

(E)-(CR₄R₅CF₂CF₂O)_j’-

wherein R is₄And R₅Identical or different from each other and selected from H, Cl or perfluoroalkyl, for example having 1 to 4 carbon atoms, j' being an integer giving a molecular weight of the above-mentioned molecular weight; the units within the fluoropolyoxyalkylene chain may be interconnected to the following structure:

-(CR₄R₅CF₂CF₂O)_p’-R’_f-O-(CR₄R₅CF₂CF₂O)_q’-

wherein R'_fIs a fluoroalkylene group, e.g., having 1 to 4 carbon atoms; p 'and q' are integers such that the molecular weight is in the molecular weight range as described above;

(F)-(CF(CF₃CF₂O)_j”-(R’_f)-O-(CF(CF₃CF₂O)_j”-

j 'is an integer giving the above molecular weight, R'_fIs a fluoroalkylene group having 1 to 4 carbon atoms.

Examples of compounds included in formula (I) have the following formulae:

(III)T’-O-(CF₂CF₂CF₂C)_q-T’

(IV)T”-O-(CF₂CF₂O)_m(CF₂O)_n-T”

wherein T ═ CF₂-COOH，T’＝-CF₂CF₂-COOH; subscripts m, n and q are integersP is an integer, these subscripts being of such value that the number average molecular weight is in the range of 500-10,000, preferably in the range of 1,000-4,000; in structure (II), the ratios m/n and p/m are between 0.5 and 5; in structure (IV), the ratio m/n is between 0.1 and 10.

Preferred compounds are those having structure (IV).

Detailed Description

Compounds of the formula (I), in particular compounds of the formulae (II), (III) and (IV), are known. They may be prepared, for example, by photooxidation of fluoroolefins according to USP 3,665,041, or according to EP 148482 in which the preparation of those compounds of structure (III) is also described.

The process described in the above patent results in the production of a structure with COF end groups which are then converted to carboxylic acids by hydrolysis with water at temperatures between 40 ℃ and 80 ℃.

These perfluoropolyether carboxylic acid derivatives are preferably applied to the sizing of the oil repellent paper in the form of salts dissolved or emulsified in water or mixtures of water with alcohols, glycols, ethers. As the alcohol, isopropyl alcohol, ethanol, methanol, tert-butyl alcohol; as the ether, dipropylene glycol monomethyl ether; as the glycol, ethylene glycol or propylene glycol may be used.

The salt is obtained by using inorganic base, such as NaOH, KON, NH₄OH, and R₁(R₂)(R₃) An N-type organic base, wherein R₁＝R₂Alkyl or hydroxyalkyl, R₃Is H, alkyl or hydroxyalkyl, such as methylamine, diethylamine, triethylamine, ethanolamine, diethanolamine, triethanolamine, morpholine, obtained by neutralizing the acid.

A further object of the present invention is an aqueous composition comprising:

A) 1% to 60% by weight, preferably 15% to 25% by weight, of a compound of formula (I) in salified form, and optionally

B) 0.5% to 25% by weight, preferably 1% to 5% by weight, of a solvent selected from alcohols, glycols, ethers, preferably selected from isopropanol, ethanol, methanol, tert-butanol, dipropylene glycol monomethyl ether, ethylene glycol, propylene glycol; and

C) water, as a complement to 100.

The salt cation is selected from the group consisting of alkali metals, ammonium, and protonated forms of primary, secondary or tertiary amines.

The compositions are chemically and physically stable at temperatures in the range of 0 ℃ to 60 ℃, whereby they are storable for a long period of time. The temporary freezing of the composition is reversible. This represents an advantage of the composition of the present invention.

The compositions of the present invention, after dilution with water, are useful as sizes for grease proofing paper in wet end applications, surface sizing or coating applications.

The size press method consists in surface sizing the paper and applying a treatment composition on both sides of the pre-formed paper by means of a roll system (size press) to impart oil repellency thereto.

The wet end method consists in bulk sizing with the composition of the invention, starting from a cellulose pulp formed in water. The pulp may be formed from virgin, soft or hardwood, may be treated with the sulphate and/or sulphite process, may be suitably refined, or formed from regenerated cellulose pulp, or by a mixture of the two pulps. The dry cellulose concentration in the slurry is in the range of 0.1% to 10% by weight. The pulp may contain additives commonly used in the paper industry, for example organic or inorganic fillers, such as talc, kaolin, calcium carbonate or titanium dioxide; auxiliaries such as starches, dextrins, retention agents, flocculating agents, buffer systems, fungicides, bactericides, chelating agents, binders such as ASA (alkenyl succinic anhydride) or AKD (alkyl ketene dimer). The cellulosic suspension may have an acidic or basic pH, preferably basic.

Generally, the composition of the invention is added to an aqueous slurry of cellulose in order to obtain paper having a content of acid of formula (I) or salt thereof of 0.05% to 2% by weight relative to the weight of dry cellulose.

In order to improve the product retention on the cellulose fibres, it is preferred to add a fixing or retention agent to the pulp. The fixative is generally a cationic compound, usually polymeric in nature, having a molecular weight of 10,000-5,000,000, added in an amount of 0.01% to 1% by weight of the cationic compound based on dry cellulose. For example, the fixative is the following compound: cationic polyacrylamide, polyamine, polyamidoamine-epichlorohydrin or dimethylamine-epichlorohydrin copolymer, polyethyleneimine, polydiallyldimethylammonium chloride. Chelating agents may be added to the pulp to moderate the water hardness.

After addition of the composition of the invention to the cellulose pulp, the water is removed to obtain wet paper according to standard procedures used in the paper industry, which is dried, for example, at a temperature in the range of 90 ℃ to 130 ℃.

In a typical coating application, 0.2% to 3% by weight of the compound of formula (I) is added to a coating suspension containing, for example, inorganic compounds such as calcium carbonate, kaolin, titanium dioxide and pigment binders based on styrene-butadiene copolymers, acrylic copolymers and vinyl acetate-containing copolymers.

It has been found that, in addition to imparting oil repellency to paper, the compounds of formula (I) impart anti-adhesive properties to the paper, which facilitate, for example, the release of paper wound on a roll.

The following examples illustrate the invention without limiting the scope thereof.

Examples

Evaluation of oil repellency

The oil repellency evaluation was performed by the following tests:

kit test

This test is also known as TAPPI 557 method. According to the kit test, solutions having decreasing surface tension values shown in table 1 were prepared.

TABLE 1

Solution No. Castor oil% (v) toluene% (v) n-heptane% (v)

1 100 0 0

2 90 5 5

3 80 10 10

4 70 15 15

5 60 20 20

6 50 25 25

7 40 30 30

8 30 35 35

9 20 40 40

10 10 45 45

11 0 50 50

12 0 45 55

The sized sample paper was placed on a flat and clean black surface. The test was started from solution No. 12. A drop of the test solution was allowed to fall onto the paper from a height of 25 mm. The drop of solution was allowed to contact the paper for 15 seconds, then it was removed with a clean blotter paper and the surface under the drop was inspected. If the surface has darkened, the sample fails the test. The experiment was repeated with solution No. 11. If the test specimen fails, the test is continued with solution number 10 and then with the other solutions of decreasing number until a solution is found that does not cause darkening of the underlying surface. The number of the solution is the kit test value assigned to the paper.

The kit test is widely used for the rapid evaluation of the oil repellency of papers sized with fluorinated compounds, since it allows the evaluation of the grease resistance of the paper in a very short time (about 20 seconds).

However, the evaluation given by this test is not always reliable. For example, sized papers with high kit test values may show poor barrier properties under special conditions, for certain fats, e.g. temperatures above room temperature or fat mixtures with particular aggressiveness.

This is because the solutions tested by the kit distinguish the individual levels of grease resistance treatment and therefore the individual kit test values are given essentially in terms of surface tension.

In addition, in this process, a mixture of castor oil, toluene and heptane is used, which, in particular the latter two, are compounds that never occur in any of the fats or oils normally in contact with the sized paper.

Furthermore, it turns out that the penetration capacity of animal or vegetable fats depends not only on the surface tension, but also, for example, on the presence of reactive groups, such as carboxyl groups.

For the reasons mentioned above, the following performance tests were used, which simulate more realistic use conditions in terms of fat type, contact time and use temperature of the grease-proof paper.

-RP-2 folding test (Ralston folding test)

The reagents and instrumentation necessary for this assay are available from Ralston Purina (R). The Ralston fold test (RP-2 test) is commonly used to evaluate resistance to oil penetration in grease resistant paper used for pet food packaging. The sample to be detected is adjusted and adapted for 24 hours at 23 ℃ and 50 +/-2% relative humidity. A piece having a size of 10cm X10 cm was cut out. The cut sheet is positioned on a flat, smooth and rigid surface, i.e. on a piece of coated paper on which a grid containing 100 small squares is printed, the grid having a surface of exactly the same size as the sample to be examined. The specimen is slightly folded along a diagonal before being positioned on the grid. The formed fold is then reinforced with a suitable press roll; the press roll had a weight of 2040 + -45 g, a diameter of 9.5cm and a width of 4.5cm, and was covered with a rubber layer of controlled hardness having a thickness of 0.6 cm. During the crimping process, the speed of the rolls must be 2-3 cm/sec. To fold the sample along two diagonal lines, a second fold is made by folding the paper on the opposite side. The creased specimen is transferred onto the grid so that it completely covers the surface of the grid. A metal ring with a diameter of 7.5cm was placed on the paper sample to be examined. A metal tube (2.5 cm in height and 2.5cm internal diameter) was placed in the centre of the sample and 5g of sand (Ottawa sand, 20-30 mesh) was poured into the tube. The tube was then removed to form a sand cone in the center of the sample. Then 1.3ml of a special synthetic oil containing 0.1% by weight of a red organic dye, supplied by Ralston Purina, was added to the sand cone by means of a syringe. According to the Ralston-Purina company, this oil is a mixture of triolein and free oleic acid, and therefore it simulates fairly well the composition of food fat.

Typically at least 4 samples of the same paper sample were prepared for this test. The sand-loaded samples were then stored in an oven at 60 ℃ and a relative humidity of 50. + -. 2% for 24 hours.

Finally, the sanded paper sample was removed and the underlying pigmented oil grid surface evaluated. Each colored panel represents 1% of the sample surface. The final value is the average of the results obtained on at least 4 specimens of the same sample. The results of the Ralston folding test (RP-2 test) thus represent the number of colored panels, which also represents the percentage of colored panels in the grid. The sample acceptability limit was 2% of the colored surface of the grid.

Resistance test to oleic acid

The resistance test to oleic acid was used to evaluate the ability of paper sized with oil repellent additives to resist the heat penetration of oleic acid. This test is very interesting for checking the presence of high oil repellency under practical conditions, since among those fatty acids that make up animal and vegetable oils, oleic acid is the most widespread fatty acid, in terms of percentage. It is well known that fats of vegetable or animal origin are formed from triglycerides, i.e. from glycerides of fatty acids. The penetration of triglycerides in sized grease-proof paper is lower than that exhibited by the free fatty acids alone.

Among the acids that make up triglycerides, oleic acid is absolutely the most abundant. Furthermore, all fats and oils contain variable amounts (in the range of 0.1-5%) of free fatty acids; the hydrolysis process of triglycerides due to the conditions of use of fats and oils, such as the presence of high temperatures and alkaline environments during cooking, can increase the free fatty acids.

Oleic acid was therefore chosen as representative of fatty acids that are capable of penetrating the sized grease-resistant paper.

To carry out the test, a sample of sized paper is taken, a square surface of about 10X 10cm is cut out and placed in an oven at 60 ℃. Then 20 drops of pure oleic acid were placed on the sample. The sample with the oleic acid drop was placed in an oven at 60 ℃ for 2 hours. After this time, the oily acid drops were removed with blotter paper and the sample was placed on a dark surface. The penetration of oleic acid into the paper is shown by the darkening of the area under the oleic acid drop. If no darkening was detected in any of the examined regions, the test was considered positive (i.e., resistance to oleic acid was determined). Conversely, the test is considered negative and the test specimen does not show resistance to oleic acid.

The Eukanuba test

This test is particularly useful for verifying the suitability of grease resistant paper for use in pet food packaging. Briefly, the test involves contacting pet food with a test paper sample under standardized conditions. For standardizing the test, belts are usedThe pet food is available in europe and the united states, under the trademark pet food. This material is characterized by an average fat content of at least 14% by weight. The Eukanuba pet food was finely ground in a mortar. A sample of grease-proof paper of size 10X 10cm was cut out to be tested. The sample was folded in a standard manner along the diagonal as was done in the RP-2 test and placed on a square sheet having the same characteristics as the paper used in the Ralston Purina fold test. A metal ring having an inner diameter of 7.2cm and a height of 2.5cm was placed in the center of the sample. 60g of ground pet food was then taken and placed evenly within the loop over the paper sample to be tested. A 1.5kg weight (cylindrical, having the same smooth lower surface as the ring) was then placed on the ground pet food placed on the paper sample. The whole was placed in an oven at 60 ℃ and 50% relative humidity for 24 hours. After this time, the weight and pet food were removed and the sample surface was examined for fat spotting, which is evidence of fat penetration that occurred. The test results are expressed as a percentage of the surface stained. In order to obtain effective results, at least 4 specimens belonging to the same treatment were tested, and at the mostThe final results are the average of 4 trials. If the stained surface is below 2%, the test is considered positive.

Resistance test to trementine (turpentine test TAPPI T454 om-00)

Weigh 5g of worthwhile sand (20-30 mesh) and place them through a funnel onto a sample of sized paper having a size of 10 x 10cm, placed in turn on a white piece of copperplate paper. The funnel must have a horizontally cut stem so that the sand is placed conically on the specimen. 1.1ml of colored trementine (about 1% red dye) was dropped through a graduated pipette onto the top of the sand cone. The test time was recorded. For the first 5 minutes, every 1 minute the paper sample was removed from the underlying sheet and a potential trementine stain was observed on the white sheet as a marker (marker). After the first 5 minutes, the procedure was performed every 3 minutes up to a maximum of 30 minutes (1800 seconds).

If after 30 minutes no staining was observed on the underlying white paper sheet, the test was positive.

Resistance test to fatty acids

Starting from each pure compound, 5 mixtures of free fatty acids were prepared. The mixture considered had the following composition:

	mixture A (% by weight)	Mixture B (% by weight)	Mixture C (% by weight)	Mixture D (% by weight)	Mixture E (% by weight)
						Castor oil	80	-	-	-	-
Oleic acid C18	20	75	62	41	9
						Linoleic acid C18	-	11	4	3	2
Palmitic acid C16	-	14	32	38	18
						Lauric acid C12	-	-	2	8	56
Capric acid C10	-	-	-	3	6
						Octanoic acid C8	-	-	-	1	8
Hexanoic acid C6	-	-	-	6	1

At least half an hour prior to the test, 5 containers each containing a single fatty acid mixture designated A, B, C, D, E were placed in an oven maintained at 60 ℃ to ensure compositional and temperature uniformity. In fact, the mixture appears to be a waxy solid with a variable melting point at room temperature.

Then, 10 specimens having a size of 5X 5cm were cut out of each specimen to be tested. The samples are placed in an oven at 60 ℃ and carefully placed on a dark surface, such as a black card. Several drops of the test mixture were then placed on each of them. At least two samples were used for each mixture.

At the end of this operation, the oven was turned off and the sample was allowed to contact the test mixture droplet for 10 minutes. After this time, the oven was opened and the drop of the mixture was removed with blotter paper. Penetration of the test mixture into the paper sample is indicated by the darkening of the area under each drop. For each test mixture, the test was positive if no permeation occurred. The test results are indicated by the letters of the test mixtures before the first test mixture that permeated the sample.

Tests carried out by the applicant have shown that the permeability of hot fatty acids at temperatures between 40 ℃ and 60 ℃ depends on their chemical structure. In particular, among the linear fatty acids, the penetration capacity of the hot fatty acids on the paper sized with the oil-repellent product depends mainly on the length of the hydrocarbon chain, i.e. the number of carbon atoms of the fatty acid. The lower the number of carbon atoms, the shorter the time required for the fatty acid droplets to penetrate the sized paper at a constant temperature. The applicant has also found that the presence of unsaturation in the linear fatty acid structure does not substantially alter its permeability in the sized paper sample for the same fatty acid without unsaturation when the number of carbon atoms is the same.

These considerations are based on the fatty acid test for the evaluation of grease repellency properties. This test implies the contact of a paper sample sized with an oil-repellent substance with a mixture of hot fatty acids having a variable composition from a to E, so that the average length of the hydrocarbon chains decreases.

Mixture A contained 20% by weight of free fatty acids, diluted in 80% by weight of castor oil. It has low penetration power and is used to identify low treatment levels, such as those necessary to produce disposable paper for hamburgers and general snacks. The size paper commercially used for the above purpose generally has a kit test value of 3 to 5.

The compositions of blends B, C, D and E represent the compositions in the fatty acids olive oil, animal oil, butter and coconut oil, respectively.

The test is an effective alternative to the kit test in terms of the time it takes to complete, and the oil and grease resistance properties of paper are evaluated under more realistic conditions, since it uses the fatty acids present in the triglycerides contained in commonly used fats and oils.

Evaluation of Release Properties of paper Carriers (paper supports)

Test I

The release properties of the paper carrier were evaluated by cutting out 10 squares of paper to be tested having a size of 10 x 10 cm. The samples were stacked on top of each other with the glued side facing up. Then a metal square of the same size (which was exactly adhered to the surface of the sample) was placed thereon, and a weight was placed thereon so that the total weight applied to the paper sample stack was 3 kg. The oven was maintained at 50+1 ℃ and 50 ± 2% relative humidity for 15 minutes. At the end the weight was removed. If the paper samples are separable from each other, the test is passed.

Test II

This test allows quantitative determination of the release effect.

An adhesive tape having a size of 1X 5cm was attached to the paper sample, and a uniform pressure was applied thereto by a 70g aluminum weight for 5 minutes. After this time, the weight was removed and the force required to separate the tape from the paper sample was measured by a force gauge. Three measurements were made for each sample. The measured forces are expressed in g and the values shown in the table represent the average of three tests.

Example 1

Preparation of the Compound of formula (IV) in salified form

500g of COF-CF₂O-(CF₂CF₂O)_m(CF₂O)_nCF₂COF (where m/n is 2.5, anddiacyl fluoride with an average molecular weight equal to 1500) with 250ml of demineralized water and kept at 60 ℃ for 2-4 hours with stirring until complete conversion of the COF end groups to COOH, as checked by FT-IR spectroscopy. When the COF group is in the region of 1880-1890cm^-1The reaction is complete when the absorption typically disappears. When the reaction was complete, stirring was stopped, the mixture was cooled at room temperature and the phases were allowed to separate for 4 hours, the upper aqueous phase was removed and the fluorinated phase was heated to 100 ℃ under vacuum (1 torr) to remove dissolved water.

By using¹⁹The product was characterized by F-NMR spectroscopy, and its molecular weight, equivalent weight and complete absence of COF end groups were determined successively.

50g of the dicarboxylic acid thus obtained are then added, with stirring, to 200g of a water/isopropanol (90/10v/v) mixture containing 9g of a 30% ammonia solution.

It was stirred at room temperature for 1 hour until the acid was completely neutralized. A translucent emulsion is obtained having a pH of between 8 and 9 and containing 20% by weight of the compound of formula (IV) salified with ammonia.

Preparation of oilproof paper by wet end treatment

An aqueous slurry of virgin fibers consisting of 50% by weight maple hardwood (maple hard wood) and 50% eucalyptus softwood (eucalyptus soft wood) was refined at 33 ° sr (chopper grades) and diluted with water until a slurry containing 0.4% by weight dry cellulose was obtained. To this slurry was added 0.75% by weight, relative to dry wood, of cationic Starch (Cato 235, National Starch) precooked in 5% by weight aqueous suspension at 90 ℃ for 30 minutes.

After dilution with water, the salified product emulsion of formula (IV) prepared as above is added to the slurry in such an amount as to obtain a cellulose pulp having a concentration of oil-repellent product (relative to dry wood) of 0.3%, 0.4%, 0.5% and 0.7% by weight, respectively. To the suspension obtained was added a solution of an industrial cationic coagulant (dimethylamine epichlorohydrin, Nalco 7607, Nalco Corp.) in an amount of 0.4% by weight relative to the dry wood.

The resulting slurry had a pH of about 7.5 and oil-repellent product contents of 0.3%, 0.4%, 0.5% and 0.7% by weight, respectively, and was transferred to a laboratory web forming machine. In each test, a wet paper sample was retrieved and dried in a press at 105 ℃ for 2 minutes. The weight of the paper sample obtained is equal to 70g/m². By analysis of the total fluorine on paper samples (ASTM D3761-84 method), they were found to contain 0.3%, 0.4%, 0.5% and 0.7% by weight of oil-repellent product, respectively. This shows that essentially all of the oil-repellent compound contained in the treatment emulsion is retained on the cellulose fibres, so that essentially 100% product retention occurs.

The oil repellency properties of the test specimens evaluated by the above tests are shown in Table 1 below.

Table 1: oil repellency of paper samples sized at the wet end with the product of the invention

% by weight based on dry fibre	Test kit	RP-2 fold test (% of soiled surface)	Oleic acid test	Eukanuba test (% of stained surface)	Turpentine test (seconds)	Fatty acid test
							0.3	7	0	Positive for	1.5	1800+	E
0.4	8	0	Positive for	0	1800+	E
							0.5	9	0	Positive for	0	1800+	E
0.7	10	0	Positive for	0	1800+	E

The paper obtained passed all oil repellency tests even at very low fluorinated compound doses.

Examples 2 to 7 (comparative)

Preparation of oilproof paper by wet end treatment with commercial products

Example 1 was repeated, but instead of the salified product of formula (IV) added to the pulp, the following respective commercially available oil-repellent products were added in amounts such as to have an oil-repellent product content of 0.3% calculated as dry fibre in the final dry paper sample:

2)(Asahi Glass) formed from an aqueous dispersion of a diethanolamine salt of a perfluoroalkylethyl phosphoric acid;

3)Lodyne(Ciba) formed from an aqueous dispersion of an ammonium salt of a perfluoroalkylcarboxylic acid containing a thioether linkage;

4)Zonyl(DuPont) formed from an aqueous dispersion of a cationic acrylic copolymer containing perfluoroalkyl segments;

5)Lodyne(Ciba) formed from an aqueous dispersion of a derivative of an amino acid (aminoacidic derivative) containing a perfluoroalkyl segment;

6)Foraperle(Atofina) formed from an aqueous dispersion of a cationic acrylic copolymer containing perfluoroalkyl segments;

7)(3M) formed from an aqueous dispersion of a mixture of ammonium salts, mono-and diesters of bis (N-ethyl-2-perfluoroalkylsulfamoylethyl) phosphoric acid, wherein said diesters are not higher than 15% by weight.

The oil repellency properties of the sized paper samples in examples 2-7, compared to those of example 1, are shown in Table 2.

Table 2: comparison of oil repellency properties of paper samples obtained by Wet end treatment

Example 8

Preparation of oilproof paper by size-applying press treatment

The paper weight is 65g/m²The paper carrier (paper support) of (1) was formed in a laboratory paper forming machine by using a slurry of native wood cellulose consisting of 70% by weight of maple hardwood and 30% by weight of eucalyptus softwood, to which was added 0.2% by weight relative to dry fibers of a cationic coagulant formed of a dimethylamine-epichlorohydrin copolymer. The wet paper was partially dried in a hot-air oven until a moisture of about 20% by weight was obtained.

3 bar (3X 10) between cylinders at room temperature in a size press apparatus⁵Pa) treating the paper obtained with the aqueous dispersion under pressure; said aqueous dispersion containing 4% by weight of a non-ionic starch (C Star Film TCF 07324, Cerestar), cooked beforehand at 90 ℃ for 30 minutes and to which the salified product of formula (IV) of example 1 is added in concentrations of 0.4%, 0.5% and 0.6% by weight, to obtainThe paper, after drying at 105 ℃ for 3 minutes in a press, had a content of salified product (IV) of 0.4%, 0.5% and 0.6% by weight, respectively, with respect to the dry wood. The properties of the resulting paper are described in table 3 below.

Table 3: oil repellency of paper samples sized in the size press with the product of the invention

% by weight, based on dry fibre	Test kit	RP-2 fold test (% of soiled surface)	Oleic acid test	Eukanuba test (% of stained surface)	Turpentine test (seconds)	Fatty acid test
							0.4	8	0	Positive for	0	1800+	D
0.5	9	0	Positive for	0	1800+	D
							0.6	10	0	Positive for	0	1800+	E

Examples 9 to 14 (comparative)

Preparation of oilproof paper by size-press treatment with commercially available products

Example 8 was repeated, treating the paper in a size press but not with the salified product of formula (IV) but with each of the following commercially available oil-repellent products, added in an amount such as to give an oil-repellent product of 0.4% by weight relative to dry wood:

9)(Asahi Glass) formed from an aqueous dispersion of a diethanolamine salt of a perfluoroalkylethyl phosphoric acid;

10)Lodyne(Ciba), formed from carboxylate salts of perfluoroalkyl-based compounds, containing thioether linkages;

11)Zonyl(DuPont) formed from an aqueous dispersion of a cationic acrylic copolymer containing perfluoroalkyl segments;

12)Lodyne(Ciba) formed from an aqueous dispersion of a derivative of an amino acid containing a perfluoroalkyl segment;

13)Foraperle(Atofina) formed from an aqueous dispersion of a cationic acrylic copolymer containing perfluoroalkyl segments;

14)(3M) formed from an aqueous dispersion of a mixture of ammonium salts, phosphoric monoesters and diesters of bis (N-ethyl-2-perfluoroalkylsulfamoylethyl) phosphoric acid, wherein said diesters are not higher than 15% by weight.

The oil repellency properties of the sized paper samples in examples 9-14, compared to those of example 8, are shown in Table 4.

Table 4: comparison of oil repellency properties of papers obtained by treatment in the size press

Examples 15 to 16 (comparative)

Preparation of oilproof paper by wet end treatment with commercial products

Example 1 was repeated, but instead of the salified product of formula (IV) added to the pulp, the following commercially available oil-repellent products were added, respectively, in such an amount in the pulp as to have an oil-repellent product content of 0.5% on a dry basis:

15)Fluorolink PT(Solvay Solexis) consisting of an aqueous dispersion of an ammonium salt of perfluoropolyether ethoxy phosphoric acid;

16)Fluorolink PT(Solvay Solexis) consisting of an aqueous dispersion of a polyurethane having perfluoropolyether segments and carboxylic acid functions neutralized with triethylamine.

The oil repellency properties of the sized paper samples in examples 15, 16, compared to those in example 1, are shown in Table 5.

The results show that the product of the invention is capable of imparting high resistance to hot fatty acids to paper.

Table 5: comparison of oil repellency properties of paper samples obtained by Wet end treatment

Example 17

Sizing-press treatment of card paper by coating with a formulation containing a salified product of formula (IV) of example 1

Paper weight of 280g/m was coated with 65% by weight of total solids formulation by means of a laboratory film coater²The sample of cardstock (coupled card), said formulation having the following composition:

-layered kaolin 41.2%;

-titanium dioxide 10%;

13% of styrene-butadiene latex;

1.0% of the product of example 1.

The coating temperature during application was 50 ℃ and the coating thickness was 1.2 mils (about 30 nm). The wet, coated cardstock was dried in an oven at 110 ℃ for 2 minutes. The sample obtained had an oil resistance value equal to 7, determined according to the kit test.

Example 18

External sizing with oil repellency with a formulation containing a hot-melt polymer and a salified product of formula (IV) of example 1 Preparation of paper with Release Performance

In a composition comprising 49% by weight of a hot-melt acrylic polymer(s) ((R))59-598, Croda) is added with 2% by weight, relative to the weight of the acrylic polymer, of the salified product of formula (IV) of example 1. This was then diluted with water until a dispersion having a solids content of 25% by weight was obtained. Using a laboratory film coater, the weight of the dispersion-coated paper prepared above was 65g/m²And then dried at 105 c for 3 minutes. In this way, the solid matter contained in the dispersion is coated on the paper, about 5g/m²。

The properties of the resulting coated paper were as follows:

-release properties:

-test I: positive for

Test II: releasing force: 0.8g

-oil-repellent properties:

kit test 10

Example 19 (comparative)

Example 18 is repeated, but without addition of the salified product of formula (IV) of example 1. The properties of the coated paper thus obtained were as follows:

-release properties:

-test I: negative of

Test II: releasing force: 160g

-oil-repellent properties:

-kit test: 1

Claims (13)

1. Use of a perfluoropolyether having the structure:

(I)T-O-R_f-T

wherein

T＝-CF₂-COOH or-CF₂CF₂-COOH；

R_fIs a perfluoropolyoxyalkylene chain or a fluorinated polyoxyalkylene chain having a number average molecular weight in the range of 500-10,000, formed of one or more repeating units, statistically distributed along the chain, having the following structure:

(CFXO)，(CF₂CF₂O)，(CF₂CF₂CF₂O)，(CF₂CF₂CF₂CF₂O)，

(CR₄R₅CF₂CF₂O)，(CF(CF₃)CF₂O)，(CF₂CF(CF₃)O)，

wherein X ═ F, CF₃；R₄And R₅Equal to or different from each other, selected from H, Cl, or a perfluoroalkyl group having 1 to 4 carbon atoms.

2. Use according to claim 1, wherein R_fSelected from:

(A)-(CF₂CF(CF₃)O)_a(CFYO)_b-

wherein Y is F or CF₃(ii) a a and b are integers such that the molecular weight is within the above range; a/b is between 10 and 100;

or the repeating units represented in (a) may be linked in the following structure:

-(CF₂CF(CF₃)O)_a(CFYO)_b-CF₂(R’_f)CF₂-O-(CF₂CF(CF₃)O)_a(CFYO)_b-

wherein R'_fIs a fluoroalkylene group having 1 to 4 carbon atoms;

(B)-(CF₂CF₂O)_c(CF₂O)_d(CF₂(CF₂)_zO)_h-

wherein h is 0 or an integer; c, d is an integer such that the molecular weight is within the above range, c/d is between 0.1 and 10; h/(c + d) is between 0 and 0.05; z is 2 or 3;

(C)-(CF₂CF(CF₃)O)_e(CF₂CF₂O)_f(CFYO)_g-

wherein Y is F or CF₃(ii) a e, f, g are integers such that the molecular weight is within the above range; e/(f + g) is between 0.1 and 10, f/g is between 2 and 10;

(D)-(CF₂(CF₂)_zO)_s-

wherein s is an integer such that the molecular weight is within the above range, and z is 2 or 3;

(E)-(CR₄R₅CF₂CF₂O)_j’-

wherein R is₄And R₅Identical or different from each other and selected from H, Cl or a perfluoroalkyl group having 1 to 4 carbon atoms, j' being an integer such that the molecular weight is within the above-mentioned range; the units inside the perfluorinated polyoxyalkylene chain or the fluorinated polyoxyalkylene chain are connected into the following structure:

-(CR₄R₅CF₂CF₂O)_p’-R’_f-O-(CR₄R₅CF₂CF₂O)_q’-

wherein R'_fIs a fluoroalkylene group having 1 to 4 carbon atoms; p 'and q' are integers such that the molecular weight is within the above range; or

(F)-(CF(CF₃)CF₂O)_j”，-(R’_f)-O-(CF₃)CF₂O)_j”

j ' is an integer, R ' such that the molecular weight is within the above range '_fIs a fluoroalkylene group having 1 to 4 carbon atoms.

3. Use according to any one of claims 1 or 2, wherein the perfluoropolyether has the formula (IV):

T”-O-(CF₂CF₂O)_m(CF₂O)_n-T”

wherein T ═ CF₂-COOH and the indices m, n are integers such that the number average molecular weight is in the range 500-10,000, the ratio m/n being between 0.1 and 10.

4. The use according to claim 3, wherein said perfluoropolyether has a number average molecular weight in the range of 1000-4,000.

5. Use according to any one of claims 1 to 4, wherein the compound of formula (I) is used in the form of a salt dissolved or emulsified in water or a mixture of water with an alcohol, a diol, an ether, wherein the alcohol is selected from isopropanol, ethanol, methanol, tert-butanol; the ether is dipropylene glycol monomethyl ether; the dihydric alcohol is selected from ethylene glycol or propylene glycol.

6. An aqueous composition comprising:

A) from 1% to 60% by weight of a compound of formula (I) as claimed in claim 1 in salified form, and

B) water was used as a complement to make up to 100.

7. The composition according to claim 6, wherein the compound of formula (I) in salified form is present in an amount ranging from 15% to 25% by weight.

8. The composition of claim 6, further comprising 0.5 wt% to 25 wt% of a solvent selected from the group consisting of alcohols, glycols, ethers.

9. The composition of claim 8, wherein the solvent is present in an amount of 1 wt% to 5 wt%.

10. The composition of claim 8 wherein the solvent is selected from the group consisting of isopropanol, ethanol, methanol, t-butanol, dipropylene glycol monomethyl ether, ethylene glycol, propylene glycol.

11. The composition according to claim 6 or 8, wherein the salified form of the compound of formula (I) is a salt of the compound of formula (I) with an alkali metal, ammonium, and a protonated form of a primary, secondary or tertiary amine.

12. Use of the aqueous composition of any of claims 6 to 11 for sizing oilproof paper.

13. Oilproof paper obtainable by treatment with a composition according to any of claims 6 to 11, containing from 0.05% to 2% by weight, relative to dry cellulose, of an acid of formula (I) according to claim 1 or one of its salts.