AU600091B2 - Wire and felt cleaning - Google Patents

Description

600091 OF AUSTRALIA N.42864 FORM

COMMONWEALTH

PATENTS ACT 1952-1973 COMPLETE SPECIFICATION (Original) FOR OFFICE USE: Class Int. Class on0 0 Application Number: Lodged: Complete Specification Lodged: Accepted: Published: This dume t contains thet ~mndhelljts Iade 1ind;1 ScctO1i 49 and is fur Priority: Related Art: Name of Applicant: W.R. GRACE C- W Address of Applicant: 1114 Avenue of the Americas, New York, New York 10036, United States of America Actual Inventor(s): Address for Service: RICHARD PURDIE CLIFFORD THERESA CULLEN JUERGEN F. SCHUETZ ACHIM SCHENKER Davies Collison, Patent Attor:neys, 1 Little Collins Street, Melbourne 3000, Australia.

Complete specification for the invention entitled: "WIRE AND FELT CLEANING" The following statement is a full description of this invention, including the best method of performing it known to us:- -1r 'Il a 4 4 Atfe t r'I 2 BACKGROUND OF THE INVENTION The manufacture of paper typically involves the processing of a carefully prepared aqueous fiber suspension to produce a highly uniform dry paper sheet.

Three steps included in the typical process are sheet forming, where the suspension is directed over a porous o 0a,, mesh or "wire" upon which fibers are deposited while H liquid filters through the wire; sheet pressing, where 1 0 the formed sheet is passed through presses covered with porous "felt" to extract retained water from the sheet, to improve the sheet's uniformity, and to impart 4eo°4° surface quality to sheet; and paper drying, where residual water is evaporated from the sheet. The sheet may then be further processed into the finished paper 'o product.

It is well known that evaporation of water is energy intensive and thus relatively expensive.

4,4 Consequently, efficient papermaking is dependent upon 04,;20 extracting water during the forming and pressing operations, and avoiding sheet defects which render the dried sheet unfit for use. Wires and felts are thus particularly important because they affect not only water removal but, because of their intimate contact1 with the sheet, the quality of the sheet itself. Soils allowed to collect on the wire and felt can affect their water removal efficiency and can be transferred to the sheet material to create defects.

The quality of the aqueous fiber suspension used to produce sheet is dependent upon many factors, including the wood and water used as raw materials, the 3 composition of any recycled material added to the process, and the additivec used during preparation of the suspension. Thus a variety of dissolved or suspended materials can be introduced into the 5 manufacturing process, including both inorganic materials such as salts and silts, and materials which are organic in nature such as resins or "pitch" from °o the wood, and inks, latex, and adhesives from recycled paper products. A build up of "soil" containing 0 inorganic and/or organic materials on wires and felts during the manufacturing process is recognized as a troublesome obstacle to efficient papermaking.

«ono° Methods of quickly and effectively removing oD deposits from the papermill wire and felt are of great importance to the industry. The paper machines could shut down for cleaning, but ceasing operation for cleaning is undesirable because of the consequential loss of productivity. On-line cleaning is thus greatly preferred where it can be effectively practiced. It is 20 common for a wire used in sheet forming to cycle continuously during production as a belt. The f sheet-contact portion of the cycle begins where application of the fiber suspension to the wire belt is started and continues until the formed sheet is separated from the wire surface; and the return portion of the cycle returns the wire from the position where the formed sheet has been removed from its surface to the beginning of the sheet-contact portion. On-line wire cleaning has generally been performed during the return stage where the wire is not in contact with the

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4- 0 t 0 00 forming sheet) by treating the returning wire with a cleaning liquid (typically water) often by showering the wire with liquid under pressure. The showers can be assisted by mechanical surface cleaning. Use of water showers, with or without mechanical. assistance, has not proved entirely satisfactory in preventing a build-up of either organic or inorganic metals from the wires, and additional materials have been used to provide cleaning liquids which are more effective.

Inorganic materials have best been removed using water-based formulations containing either acids or alkalis together with other chemicals such as surfactants. The organic deposits have normally been removed using organic solvents including some formulations containing aromatic compounds with low flash points or chlorinated hydrocarbons.

Papermill felts also commonly circulate continuously in belt-like fashion between a sheet contact stage and a return stage.

A clean felt is essential for effective paper manufacture since this allows efficient removal of water from the paper sheet. The cleaning procedure should remove both organic and inorganic soils of both a g.~neral and localised nature, maintain felt porosityf and condition the fabric nap without chemcal or physical attack on the substrate.

Mechanical removal, typically by blade contact, has been used to remove debris from the felt surface. However, cleaning liquids are also utilized to remove troublesome build-up of organic and inorganic deposits. The fabric composition and conformation. of many papermill felts makes them susceptible to chemical degradation. The chemicals should be easily removed by rinsing. Both continuous and

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5 shock cleaning is used in most papermills. The chemicals used include organic solvents, often chlorinated hydrocarbons. Acid and alkali based n systems are also used, but at lower concentrations than o 'o 5 used in wire cleaning. High concentrations of alkali S metal hydroxides are often unsuitable for felt cleaning as they "attack" the fabric material.

0 0 Certain organic wire and felt cleaners which were 0 0 used freauently in the past have become environmentally undesireable. Thus, greater need has developed for o0 wire and felt cleaners which remove organic deposits ao without presenting an environmental hazard. Naturally, o 6 formulations used should not be destructive of the wire 0 and felts. One material identified as suitable for this purpose is N-methyl-2-pyrrolidone. Whil.e this material might perform satisfactorily under some o? conditions, there is a continuing need for more 00oo0 effective wire and felt cleaners. The cost of N-methyl-2-pyrrolidone also discourages its use alone as a wire and felt cleaner. Moreover, there is a particular need for wire and felt cleaners which remove inorganic as well as organic deposits.

SUMMARY OF THE INVENTION We have found that combining at least one of the organic cleaning components selected from N-methyl-2pyrrolidone, e-butyrolactone, nd certain of their structurally related compounds with an alkali in both 6 water and an organic cosolvent capable of providing a stable solution at high alkalinities is surprisingly effective in removing both organic and inorganic deposits from papermill wires and felts.

According to the present invention there is provided a papermill wire and felt cleaner comprising: oope an organic cleaning component which is of aog Formula A or B as set out below 0 0 °o an inorganic alkali material; 10 a water-soluble organic solvent; and water; wherein either the weight percent of compound represented by °Formula A is from 0.5% to 50% and the weight percent of I o P' water is at least about 30%, or the weight percent of j. 15 compound represented by Formula B is from 0.5% to 20% and the weight percent of water is at least about 60%; wherein Sthe weight percent of the alkali material is from 0.25% to i| wherein the weight percent of water is 98.8 or 98.75% or less and wherein the weight percent of the organic S 20 solvent is from 0.5% up to the concentration of water, at which there is no phase separation.

The present invention is thus directed to certain combinations of organic cleaning components with alkali materials which provide surprisingly effective removal of both organic and inorganic deposits from papermill wires and felts. The alkali materials used in this ,i i_ ;e 1 -7 invention can be any of the inorganic alkali materials suitable for use in aqueous solution to remove inorganic deposits from papermill wires and felts. These materials are believed to function by hydrolysing and solubilizing the inorganic deposits and include alkali metal hydroxides (most notably sodium hydroxide and potassium hydroxide) and alkali metal metasilicates, especially sodium metasilicate. The alkali metal hydroxides are preferred, with sodium hydroxide being the most preferred from an economic and effectiveness o standpoint. The concentrations of these alkali materials needed to rapidly remove inorganic deposits can be detrimental to certain materials on which the deposits adhere, and the effectiveness of alkali when used alone is limited, particularly where organic deposits are present.

The organic cleaning component may be N-methyl-2-pyrrolidone or structurally related compounds, having the general formula: C(RI)2- C(RI)2 FORMULA A c(IR) 2 c=o i especially the formula: H C(R,)

HCR

1

C=

113 013 j_ 1, i r i I. I 8 wherein each R is independently hydrogen, methyl or ethyl and Z is methyl or ethyl. These compounds will be referred to herein as "Formula A" compounds. Most preferred is N-methyl-2-pyrrolidone itself each R. is hydrogen).

N-methyl-2-pyrrolidone is a known component of various cleaning formulations for ovens, cookware, ceramic material, no and has also been used in paint remover compositions. It o has been suggested for use as a papermill wire and felt 1o cleaner, and its relatively low toxicity makes it an o 10 acceptable material from an environmental standpoint.

The organic cleaning component may also be 6-butyrolactone or structurally related compounds having the o. general structural formula: (Rl 1 2 I0 I c R) 2 C=O FORMULA B 0 especially the formula: H2c CH 2 HCT C=O S2 o wherein R 2 is hydrogen or methyl and R, is as defined above.

These compounds will be referred to herein as "Formula B" compounds. Preferably, R, is hydrogen; a preferred organic cleat .ng component is 6-butyrolactone.

i -C r I_ i L 9 has been used as a solvent for resins, as a paint remover, and the like. Its effectivenesswhen used alone as a wire and felt cleaner is, however, limited.

We have found that by using certain organic cosolvents with water, the alkali materials described above can be combined with an organic cleaning component of Formula A or Formula B to provide stable and effective wire and felt cleaners. The preferred organic cleaning compounds oso used in this invention are N-methyl-2-pyrrolidone and 10 K-butyrolactone. Not only can organic and inorganic o, *deposits be removed simultaneously, but their removal is accomplished at surprisingly low dosages. Thus, a r particularly advantageous process is also provided for producing clean papermill wires and felts from soiled wires 0 /I and felts.

Suitable organic solvents must be capable of providing stable aqueous solutions of Formula A compounds and/or Formula B compounds at high alkalinities. That is, j the organic cosolvent with the water must provide increased effectiveness at levels where there is no phase separation into generally organic and aqueous phases. Preferred organic cosolvents which can be used in accordance with this invention to provide the improved effectiveness without causing phase separation include glycol ethers, isopropanol, and acetone. It will be appreciated that many cosolvents capable of providing product stability also have properties which make their use environmentally undesirable (eg.

relatively low flash points), and thus should be i I, I ,i 10 avoided in many circumstances where exposure or release are of concern. Preferred organic cosolvents thus include glycol ethers having the general formula: CnHn+ 0 [CH 2

CH

2

CH

2 0]m CH 2 CH2]K H in which n is an integer from 1 to 4, m is an integer from zero to two, k is an integer from zero to two, and m plus k is at least one. A particularly preferred glycol ether is 2-butoxyethanol n is 4, m is zero, and k is 1).

It is possible to apply the alkali material, the organic cleaning component, and the cosolvents separately during cleaning of a papermill wire or felt so that they mix o during the cleaning process. When thiU is done, the weight ratio of applied components should be regulated so that a o« single phase cleaning system is provided during cleaning, and the surprisingly effective treatment of this invention is attained, Generally, the weight ratio of alkali to organic cosolvent is kept at about 1:80 to about 14:1; and Swhere a Formula A compound is the organic cleaning component, its ratio to the organic cosolvent is kept at about 100:1 to about 1:40. Where a Formula B compound is the organic cleaning component rather than a Formula A compound, its ratio to the organic cosolvent is generally kept at aboit 40:1 to about 1:40. The amount of water present should be at least equal to the amount of organic cosolvent.

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11 Accordingly the present invention also provides a method of treating papermill wire or felt to remove organic and/or inorganic deposits therefrom comprising contacting the wire or felt with a liquid mixture comprising: an organic cleaning component of Formula A or B as defined above; o an inorganic alkali material; a a water-soluble organic solvent; and 1" water; S said mixture having an organic cleaning component concentration of at least about 5 ppm based upon the total o amount of liquid contacting the wire or felt; a free o alkalinity of at least about 2 ppm based upon the total amount of liquid contacting the wire or felt; a weight ratio 6 a of alkali material to organic solvent of 1:80 to 14:1; either a weight ratio of compound of Formula A to organic solvent from 100:1 to 1:40 or a weight ratio of compound of SFormula B to organic solvent from 40:1 to 1:40; and a water content (by weight) at least as large as the organic solvent I content.

It is generally more convenient, however, to provide the components together in the form of a composition.

L I I I )C_~XII 12 Effective compositions formulated in accordance with this invention include those containing from about to about 50 weight percent of Formula A compound, preferably N-methyl-2-pyrrolidone, from about 0.5 to about 20 weight percent organic cosolvent, from about 0.25 to about weight percent alkali material, and from about 30.0 to about 98.8 weight percent water. Other effective compositions advantageously formulated in accordance with this invention contain from about 0.5 to about 20 weight percent Formula B 9 10 compound, preferably 4-butyrolactone, from about 0.5 to ao about 20 weight percent organic cosolvent, from about 0.25 OO to about 7.0 weight percent alkali material, and from about o o 60.0 to about 98.8 percent water.

The preferred ranges are from about 5 to about 12 0 0 15 weight percent of an organic cleaning component of Formula A o or Formula B; from about 2.5 to about 12.5 weight percent of C 00 organic cosolvent; from about 2.0 to about 5.5. weight 0 s percent of alkali; and from about 60.0 to about 88,0 weight percent water, particularly where the organic cleaning o. 20 component As N-methyl-2-pyrrolidone or -butyrolactone. The L B most preferred ranges are from eoout 7.5 to about 10.5 weight percent of said organic cleaning component; from about 7.5 to about 10.5 weight percent of organic cosolvent; from about 2.5 to about 5.0 weight percent of alkali; and from about 67.0 to about 82.5 weight percent water, I f 13 particularly where 2-butoxyethanol and sodium hydroxide are used as the organic cosolvent and alkali material, respectively, and the organic cleaning component is N-methyl-2-pyrrolidone or 6-butyrolactone.

Other agents can optionally be added along with the specified ingredients, including corrosion inhibitors to protect metal substrates, thickening agents to increase contact times between the composition and the wire or felt, Go and surfactants such as amine oxides to improve the wetting 10 of the wire or felt surface. Suitable corrosion inhibitors o, for use in this manner include alkanolamine salts of aryl .oo. sulphonamide corboxylic acids, such as the product Hostacor So0o0 0KSl-X (approximately 84% active) available commercially from Hoechst. Preferred surfactants for use in this manner i 15 include n-alkyl ethoxy dimethylamine oxides where the alkyl ihas about 12 to about 18 carbons, such as the product Empigen OY (25% active) available commercially from Albright and Wilson; and lauryl/myristyl dimethylamine oxides, such as the product Empigen OB, lauryl/myristyl/cetyl polyethoxy 20 dimethylamine oxide (30% active) commercially available from Albright and Wilson.

A particularly preferred composition has the following formulation: -C c Yp- L.lllil ii---linii.i -i -Ililiii -i 14 Water 61.57% Sodium Hydroxide Solution 8.80% N- Methyl Pyrrolidone 8.80% 2-Butoxy Ethanol 8.80% Empigen OY 4.63% Empigen OB 3.70% Hostacor KSIX 3.70% 100.00% The treatment dosage does, of course, depend on the nature of the soil material, and whether cleaning is continuous or e4 10 periodic. The compositions may be employed at full strength for example by spraying the composition directly onto the felt and/or wires, especially where shock cleaning for rapid removal of build up deposits is necessary.

Accordingly the present invention also provides a method of treating papermill wire or felt to remove organic and/or inorganic deposits therefrom comprising contacting the wire or felt with a composition as defined above. However, Sparticularly where continuous cleaning is practiced, the compositions may be advantageously diluted prior to ,i 20 treatment with water or other suitable liquid, such as the aqueous liquid of the papermaking process itself. The advantages of this invention are generally realized at dosages as low as 0.01 weight percent of a composition described above, based upon the total amount of liquid used to clean the wire or felt.

"Continuous cleaning" as used herein means that the wire os'

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J I 15 felt is routinely treated at least once during the cycle between its sheet contact stage and its return stage. This routine treatment can advantageously occur during the period when the wire and felt is not in contact with sheet material the return stage). The deposited material is then typically washed away with the draining treatment liquid. However, it is contemplated that addition of the composition to the papermill process water itself can also be practiced in accordance with this invention; and that continuous cleaning during the sheet contact portion can be 0 effective. Cleaning during sheet contact provides S inhibition of soil build-uo and therefore functions in a preventive capacity rather than merely in a removal i capacity. Continuous cleaning during sheet contact is especially appropriate for wire cleaning where the inorganic and organic materials can be washed through the wire with the filtered process water, and thus can be transported away from both the wire and the sheet without affecting the sheet-forming process.

In any case, the concentration of organic cleaning component in the liquid contacting the wire or felt should generally be at least about 5 ppm, and the free alkalinity of the liquid contacting the wire or felt should generally be at least about 2 ppm (expressed as the amount of NaOH equivalent to the free hydroxyl ion present).

I L lr-r_ ,;n 16 Typically, continuous treatment in accordance with this invention will provide from about 50 ppm to about 500 ppm of organic cleaning component, and from about 20 ppm to about 200 ppm free alkalinity (as NaOH) but amounts up to, say 50,000 ppm of organic cleaning component and up to, say, 3,500 ppm free alkalinity may sometimes be used.

The following Examples further illustrate the present invention.

o os EXAMPLE I a n aoo 10 A synthetic polyester-polyamide papermill wire soiled with both inorganic and organic material was soaked in substantially pure N-methyl-2-pyrrolidone for about 30 minutes. The papermill wire was then removed So' and the amount of soil removed was simply measured by So 15 determining the difference in wire weight due to 0 a treatment.

oa A second run was made using substantially pure 2-butoxyethanol instead of N-methyl-2-pyrrolidone, and a third run was made using a 50 percent solution of S, 20 sodium hydroxide in water as the sole treatment agent.

A fourth run was made usinc a composition containing 4.3 weight percent sodium hydroxide, 8.8 weight percent 2-butoxyethanol, 5.3 weight percent (active) corrosion inhibitor and surfactants (added as Hostacor KS1-X, Fj.pigen OY, and Empigen OB), and the LIIII-L---LLI--LI~IIL~_~LI- -Is. i 1 J f 17 remainder water; and a fifth run was made using a composition containing the same weight percentages of sodium hydroxide, 2-butoxyethanol, corrosion inhibitor, and surfactants as the fourth run, but also containing 8.8 percent of N-methyl-2-pyrrolidone and the remainder water. The results of these five runs are shown in Table I below.

a TABLE I 040.* WIRE AND FELT

PERCENT

RUN CLEANER FORMULATION SOIL REMOVED 1 100% N-methyl-2-pyrrolidone 21% 2 100% 2-butoxyethanol S3 50% Sodium Hydroxide Water 4 4.3% Sodium Hydroxide 8.8% 2-butoxyethanol 81.6% Water 5.3% Corrosion Inhibitor and Surfactants S 20 5 4.3% Sodium Hydroxide 100% 8.8% 2-butoxyethanol 8.8% N-methyl-2-pyrroli one 72.8% Water 5.3% Corrosion Inhibitor and Surfactants It is evident from the results shown in Table I that the combination of N-methyl-2-pyrrolidone with the other components used in this invention provided unexpectedly superior removal of organic and inorganic deposits from the wire. Moreover, the composition of run 5 was stable, and thus may be shipped, stored, and applied with the convenience of a single phase system.

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i 18 EXAMPLE II In a sixth run, papermill wire soiled with both inorganic and organic material was soaked in substantially pure "-butyrolactone for about minutes. The papermill wire was then removed and the m 5 amount of soil removal was measured in accordance with o! the procedure of Example I. A seventh run was then made by soaking a papermill wire soiled with both a O* inorganic and organic material for 30 minutes in a composition containing 2.5 weight percent sodium 10 hydroxide, 10 weight percent 2-butoxyethanol, 10 weight percent k-butyrolactone, 5.3 weight percent (active) surfactants and corrosion inhibitor (added ae Hostacor l KS1-X, Empigen OY, and Empigen OB), and the remainder A water. The results of these two runs are shown in S 15 Table II below.

TABLE II WIRE AND FELT PERCENT RUN CLEANER FORMULATION SOIL REMOVED 20 6 100% -butyrolactone 19% 7 2.5% Sodium Hydroxide 71% 2-butoxyethanol (-butyrolactone 5.33 Surfactants and Corrosion Inhibitor 72.2% Water It is evident from the results of the sixth run that while some soil removal was achieved using J-butyrolactone alone, the degree of removal was only roughly comparable to the removal achieved using i 19 N-methvl-2-pyrrolidone alone. The results of the seventh run show that the combination of e-butyrolactone with the other components of this invention provided unexpectedly superior removal of organic and inorganic deposits from the wire. The composition of run 7 was stable and thus could be conveniently handled as a single phase system.

not* 0A 04 4

Claims (24)

1. A papermill wire and felt cleaner comprising: an organic cleaning component which is a compound represented by the Formula C(R C(R 1 2 (A) 1 I(A) C R )2 =O Sx ao wherein X is O or N-Z, each R 1 is independently selected from hydrogen, methyl, and ethyl, and Z is methyl or ethyl, an inorganic alkali material; a water-soluble organic solvent; and water; wherein either.the weight percent of component if X is N-Z is from 0.5% to 50% and the weight percent of water is at least 30%, or the weight percent of component I if X is 0 is from 0.5 to 20% and the weight percent of water is at least 60%; wherein i SI 900518, immdat. 031, a: \11714gra fop, -21- aa Ra? a a a a 0 a o oa Q S4 0 a a a a 0 a a a at aO a aft a ft a a if a us f a 4 by F- B2 is. f£n O.54-a 20% all 1 J the weight percent of the alkali material is from 0.25% to wherein the weight percent of water is 98.75% or less 5 and wherein the weight percent of the organic solvent is from 0.5% up to the concentration of water, at which there is no phase separation.

2. A papermill wire and felt cleaner according to Claim 1 wherein the inorganic alkali material is an 10 alkali metal hydroxide or an alkali metal metasilicate.

3. A papermill wire and felt cleaner according to Claim 2 wherein the alkali material is sodium hydroxide.

4. A papermill wire and felt cleaner according to any one of Claims 1 to 3, wherein the organic solvent is a glycol ether, isopropanol or acetone.

5. A papermill wire and felt cleaner according to any one of the preceding claims wherein the organic solvent is one having the general formula: CnH 2 n+10 [CH 2 CH 2 CH 2 0 m [CH 2 CH 2 0]k H 20 wherein n is an integer from 1 4, m is an integer from 0 to 2, k is an integer from 0 to 2, such that m k totals at least one.

6. A papermill wire and felt cleaner according to any one of the preceding claims wherein the organic solvent is 2-butoxyethanol. 22

7. A papermill wire and felt cleaner according to any one of the preceding claims wherein the organic cleaning component is N-methyl pyrrolidone.

8. A papermill wire and felt cleaner according to any one of Claims 1 to 6 wherein the organic cleaning component is 6f-butyrolactone.

9. A papermill wire and felt cleaner according n, *to any one of the preceding claims containing from 5 to 12 weight percent of the organic cleaning component.

10. A papermill wire and felt cleaner according to any one of the preceding claims containing from 2.0 to j 5.5 weight percent of the alkali material.

11. A papermill wire and felt cleaner according to any one of the preceding claims containing from 2.5 to

12.5 weight percent of organic solvent. 12. A papermill wire and felt cleaner according to any one of the preceding claims further comprising at least one corrosion inhibitor, thickening agent, or surfactant.

13. A papermill wire and felt cleaner according to claim 12 wherein the corrosion inhibitor is an alkanolamine salt of an aryl sulphonamido carboxylic acid, and the surfactant is a lauryl/myristyl dimethylamine oxide or a lauryl/myristyl/cetyl ethoxy dimethylamine oxide. 1- ~-Lllu- rril 4ir_- i li- III--

14. A papermill wire and felt cleaner according to any one of the preceding claims wherein the water is present in an amount from 60 to 88 weight percent.

A papermill wire and felt cleaner according to claim 1 substantially as described in Example I or II.

16. A method of treating papermill wire or felt to remove organic and/or inorganic deposits therefrom comprising contacting the wire or felt with a liquid mixture comprising: an organic cleaning component as defined in B claim 1; an inorganic alkali material; 0 o a water-soluble organic solvent; and o water; said mixture having an organic cleaning component concentration of at least; 5 ppm based upon the total amount of liquid contacting the wire or felt; a free alkalinity of at least 2 ppm based upon the total amount oQ of liquid contacting the wire or felt; a weight ratio of ee *a alki material to organic solvent of 1:80 to 14:1; o f either a weight ratio of component in which X is N-Z to organic solvent from 100:; to 1:40 or a weight ratio of component in which X is 0 to organic solvent from 40:1 to 1:40; and a water content (by weight) at least as o large as the organic solvent content. 0 0 jV

900518. Immdat.031#a\1714gra.tsp,23 24

17. A method according to Claim 16 th W1,eh th. concentration of the organic cleaning component in tho mixture is from 50 ppm to 500 ppm; and the free Ikalir y is from 20 ppm to 200 ppm, both based upon the total amount of liquid contacting the wire or felt.

18. A method according to Claim 16 or 17 in which the organic cleaning component, the alkali material,and the ao° organic solvent are added as a composition as claimed in any So i one of Claims 1 to

19. A method of cleaning papermill wires which "s"o cycle between a sheet contact stage and a return stage O according to any one of Claims 16 to 18 in which the liquid mix is added to the papermill process water so that cleaning o 4 is accomplished during the sheet contact portion of the wire 15 cycle. oo

20. A method according to any one of Claims 16 to 19 in which the organic cleaning component, the alkali material, and the organic solvent are added as a composition S containing 5 to 12 weight percent of the organic cleaning component; from 2.5 to 12.5 weight percent of organic solvent; from 2.0 to 5.5 weight percent of alkali material; and from abo~t 60.0 to aieu 88.0 weight percent of water.

21. A method of treating papermill wire or felt to remove organic and/or inorganic deposits therefrom comprising contacting the wire or felt with a composition as claimed in any one of claims 1 to isb. 0^^ c t 1 ~L 25

22. A method according to any one of claims 16 to 21 in which the inorganic alkal4. metal is an alkali metal hydroxide or an alkali metal silicate and the organic solvent is a glycol ether, isopropanol or acetone.

23. A method according to any one of Claims 16 to 22 in which the organic cleaning component is N-methyl-2-pyrrolidone or -butyrolactone. s

24. A method according to any one of Claims 16 to 23 in which the organic cleaning material is 1 0 Wi-methyl-2-pyrrolidone, the organic cosolvent is S"2-butoxyethanol; and the alkali material is an alkali metal hydroxide. A method according to any one of Claims 16 to Gone 23 in which the organic cleaning material is Do 0 15 -butyrolactone, the organic cosolvent is 2-butoxyethanol, and the alkali material is an alkali metal hydroxide. 26. A method according to Claim 16 or 21 substantially as described in Example 1 or 2. 0 41 O referred to or indicated in the specificationa dams of this application, individual.- Vooeltively, and any and all combinaio a two or more of said steps or Dated this 15th day of February 1988 W. R. GRACE CO. C(noA By its Patent Attorneys S DAVIES COLLISON