WO1989004398A1 - Feuilles de rigidite accrue constituees d'une fibre, de latex et d'un agent coalescent - Google Patents

Feuilles de rigidite accrue constituees d'une fibre, de latex et d'un agent coalescent Download PDF

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Publication number
WO1989004398A1
WO1989004398A1 PCT/US1987/002940 US8702940W WO8904398A1 WO 1989004398 A1 WO1989004398 A1 WO 1989004398A1 US 8702940 W US8702940 W US 8702940W WO 8904398 A1 WO8904398 A1 WO 8904398A1
Authority
WO
WIPO (PCT)
Prior art keywords
latex
sheet
coalescing agent
fiber
conditions
Prior art date
Application number
PCT/US1987/002940
Other languages
English (en)
Inventor
James J. Beer
Do Ik Lee
Original Assignee
The Dow Chemical Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by The Dow Chemical Company filed Critical The Dow Chemical Company
Priority to KR1019890701275A priority Critical patent/KR890701841A/ko
Priority to JP50029288A priority patent/JPH03502217A/ja
Publication of WO1989004398A1 publication Critical patent/WO1989004398A1/fr

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Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H3/00—Paper or cardboard prepared by adding substances to the pulp or to the formed web on the paper-making machine and by applying substances to finished paper or cardboard (on the paper-making machine), also when the intention is to impregnate at least a part of the paper body
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/20—Macromolecular organic compounds
    • D21H17/33—Synthetic macromolecular compounds
    • D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D21H17/35—Polyalkenes, e.g. polystyrene
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/03—Non-macromolecular organic compounds
    • D21H17/05—Non-macromolecular organic compounds containing elements other than carbon and hydrogen only
    • D21H17/06—Alcohols; Phenols; Ethers; Aldehydes; Ketones; Acetals; Ketals

Definitions

  • the present invention generally relates to sheets prepared from fiber, latex and a coalescing agent. Further, the present invention provides for a sheet having improved stiffness by employing a hard latex and a fugitive coalescing agent.
  • sheets made from fibrous materials have been described in the art.
  • Typical examples of such sheets include fine printing papers, cardboard papers, underlayment felt for vinyl floor coverings, gasket papers, roofing papers, sound- deadening papers, pipewrap, heat deflection papers and board products.
  • Stiffness is very important in printing grades of paper, especially in the lightweight grades. Methods to increase sheet stiffness are therefore desirable.
  • One potential method for increasing stiffness would be to employ a latex having greater hardness; however, use of such a latex would be limited by its ability to coalesce or form a film under the sheet preparation conditions. That is, a latex with a minimum film-forming temperature greater than the temperature a sheet reaches during preparation would not be a viable choice, unfortunately, such latexes could provide the desired stiffness, but increasing the drying temperature would be harmful to the fiber and other organic components of the sheet system.
  • U.S. Patent No. 4,225,383 generally teaches composite sheet preparation and suggests polymers which are made film-forming by the use of plasticizers can be used. This reference is, however, limited to composite sheets containing relatively high levels of filler or pigment from 60 to 95 percent based on the dried weight of the composite sheet. The subject invention, instead, focuses on sheets with no filler or medium filler levels.
  • the present invention provides a process for preparing a sheet with improved stiffness which comprises: (a) mixing in an aqueous medium a mixture comprising (i) a fiber, (ii) a latex having minimum film-forming conditions greater than the conditions the sheet reaches during drying, and (iii) a fugitive coalescing agent (b) forming the mixture into a sheet, and (c) drying said sheet under conditions less than the minimum film-forming conditions required by the latex. Additionally, the process can include the step of mixing the latex with the fugitive coalescing agent prior to the addition of the fiber in the aqueous medium.
  • the present invention may include the addition of a pigment or filler to the aqueous mixture of the process of up to 60 weight percent based on the total dry weight of the sheet. Additionally, the latex can be destabilized by combining a chemical flocculant to form the sheet.
  • the present invention further provides for a sheet prepared from the aforementioned process.
  • An advantage of the sheet is improved stiffness for various grades of paper, especially fine printing paper.
  • the process of the invention requires a fiber, a latex and a coalescing agent. More particularly, a fugitive coalescing agent is employed.
  • the process can further comprise the incorporation of fillers from low to medium levels (0 to 60 weight percent based on the total weight of the dried sheet) which are generally known in the art of sheet preparation.
  • the process of the invention requires a fiber material.
  • the fiber can be a water-insoluble, natural or synthetic water- dispersible fiber or blend thereof. Either long or short fibers, or mixtures of both, are useful.
  • the most common natural fibers are those made from wood pulp, cotton, wool and jute to name only a few.
  • synthetic fibers useful in the subject invention comprise rayon, nylon, glass fibers and polyester. More examples of other suitable fiber material are disclosed in U.S. Patent No. 4,225,383.
  • the fiber is present in a reinforcing amount. That is, sufficient fiber will be present to impart additional physical strength to the sheet, compared to a similar sheet prepared without a fiber.
  • the sheet will contain from 1 to 99, preferably from 10 to 80, more preferably from 15 to 70 weight percent fiber based on the total weight of the dried sheet.
  • the process of the invention requires a latex.
  • latex is meant a colloidaily stable dispersion of discrete polymer particles in an aqueous medium.
  • the latex employed in the subject invention is critical to imparting the desired stiffness to the sheet.
  • the latexes are termed "hard latexes" which is meant to describe a latex having a relatively high minimum film-forming temperature. That is a higher temperature than the sheet normally reaches at drying or due to the higher minimum film-forming temperature, the latex does not have sufficient residence time to adequately coalesce under normal sheet preparation conditions. More particularly, these so called “hard latexes" are non-film-forming under sheet process conditions.
  • Non-film-forming is meant to indicate a degree of latex coalescence.
  • Sheet preparation “conditions” is meant to indicate the various parameters which effect the ability of a latex to coalesce such as temperature, residence time and moisture level. Because the hard latex would not generally form a film (i.e., coalesce) the third component of the subject invention is required which is a fugitive coalescing agent.
  • the latexes employed in the subject invention are water-insoluble, natural or synthetic and may be homopolymers or copolymers of two or more ethylenically unsaturated monomers or a mixture of such polymers.
  • Monovinylidene aromatic compounds such as styrene and
  • 10 aliphatic conjugated dienes such as 1 ,3-butadiene are preferred latexes.
  • the more preferred latexes comprise styrene/butadiene.
  • Other suitable latexes generally known in the art of sheet preparation can also be advantageously employed as described
  • the latex will be present in an amount sufficient to maintain the finished sheet in the form 0 of a generally unitary sheet having sufficient body to enable it to be handled without crumbling.
  • the sheet will have from 1 to 30, preferably from 1.5 to 10, more preferably from 2 to 7. weight percent based on the total weight of the dried sheet.
  • coalescing agent As a third component, the subject process requires a coalescing agent. More particularly, the coalescing agent must be a fugitive coalescing agent. Therefore, unless otherwise indicated the term “coalescing agent” is meant to indicate a fugitive 5 coalescing agent. By “fugitive” is meant that the coalescing agent is sufficiently volatile such that under the conditions employed to form and dry the sheet, the coalescing agent will be substantially removed from the sheet.
  • Useful coalescing agents include glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, diethylene glycol diethyl ether, and propylene glycol phenol ether; glycol ether acetates such as diethylene glycol monoethyl ether acetate and ethylene glycol monomethyl ether acetate; and ketones such as acetone, methyl ethyl ketone, methyl propyl ketone, and diacet ⁇ ne alcohol.
  • glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, diethylene glycol diethyl ether, and propylene glycol phenol ether
  • glycol ether acetates such as diethylene glycol monoethyl ether acetate and
  • the coalescing agent is present in an effective amount. That is, sufficient coalescing agent will be present to assist in the deformation of the latex particles such that the finished sheet has greater stiffness than a similar sheet made without the use of a coalescing agent.
  • the coalescing agent will be present from 1 to 20, preferably from 2.5 to 15, more preferably from 5 to 10 weight percent based on the total weight of the latex solids.
  • the fugitive coalescing agent is preferentially present in the latex particle as opposed to the aqueous phase of the mixture.
  • the coalescing agent assists the hard latex to deform or coalesce on the fiber or pigments if present.
  • the hard latex is, thus, made film-forming under drying conditions less than the minimum film- forming conditions required by the hard latex.
  • the fugitive coalescing agent is substantially removed whereby the hard latex reverts and contributes to the stiffness of the final sheet. Trace amounts of fugitive coalescing agent may, however, remain in the final sheet.
  • the invention also includes "composite papers" which are non-woven fabrics containing a binder, a fiber, and a nonbinding filler.
  • These fillers are generally finely divided solids (i.e., powders) such as clay, magnesium hydroxide, or calcium carbonate. Examples of other suitable fillers are disclosed in U.S. Patent No. 4,225,383.
  • the filler level is from 0 to 60 weight percent based on the weight of the dried sheet.
  • the preferred filler range is from 25 to 45 weight percent.
  • Lower filler levels can be advantageously employed due to the excellent physical properties contributed by the hard latex.
  • the fiber, latex, coalescing agent and optional filler are combined in an aqueous medium prior to formation of the sheet. While not critical to the practice of the invention, it is generally convenient to premix the latex and coalescing agent, and add this mixture to a dispersion of the fiber and filler in water. In preparing the latex-coalescing agent mixture, it is desirable to provide a standing period so that the coalescing agent may have time to diffuse into the latex particles. Normally, a period of about one hour is sufficient. If the latex and coalescing agent are added separately to the fiber slurry, an extensive waiting period (perhaps several days or more) may be needed unless very large amounts of coalescing agent are used.
  • the latex is destabilized so as to precipitate it onto the fibers. This is conveniently accomplished by means of a floccu ⁇ lating (coagulating) agent.
  • a floccu ⁇ lating agent coagulating
  • suitable flocculants include modified cationic polyacrylamide and diallyldiethylammonium chloride for anionic latexes and partially hydrolyzed polyacrylamide for cationic latexes.
  • the aqueous slurry is formed into a sheet or web and dewatered.
  • This sheet forming and dewatering process may be accom ⁇ plished by any conventional paper-making apparatus such as a sheet mold, or a Fourdrinier or cylinder machine.
  • the composite may be desirable to densify the sheet by pressing it with a flat press or by sending it through calendering rolls. Drying of the sheet may be either by air drying at ambient conditions or by oven drying.
  • the drying temperature of a sheet is limited by the temperature at which the fiber or other organic component of the system can withstand without being damaged.
  • a latex selection was generally limited by the minimum film-forming temperature of the latex. Therefore, an advantage of the present invention is that for a given drying temperature, a harder latex may be used or for a given latex, the composite may be dried at a lower temperature.
  • Other general teachings of the use of latexes in the formation of fibrous sheets may be found, for example, in U.S. Patent Nos. 3,875,097 and 3,518,113, and West German issued patent 1 446 609.
  • a particularly useful and commercially signi ⁇ ficant embodiment of the invention includes a composite made with a latex, a high grade cellulose fiber, a filler, and a fugitive coalescing agent, wherein the finished composite is relatively thin (i.e., from 0.002 to 0.01 inches (0.05 to 0.25 mm)).
  • These composites generally will contain desirably 3 to 99, preferably 25 to 90, most preferably 35 to 70, weight percent fiber based on the total weight of the dried composite; desirably 0 to 60, preferably from 25 to 45, weight percent filler based on the weight of the dried composite; and desirably from 0.5 to 30, preferably from 0.8 to 10, more preferably from 1 to 5, weight percent (based on solids) of the latex, based on the total weight of the dried composite.
  • Such composites are useful as printing papers, and have unexpectedly superior stiffness compared to similar papers made without the fugitive coalescing agent.
  • a mixture of 50 parts kraft hardwood and 50 parts kraft softwood was dispersed in water at 1.35 percent consistency and mechanically refined into pulp having 392 CSF (Canadian Standard Freeness). The pulp was then diluted to 0.51 percent consistency. On the following day, the pulp was adjusted to a pH of about 4.1 with 0.1 N HC1.
  • a relatively hard latex was prepared from 80 parts styrene, 17 parts butadiene and 2 parts acrylic acid using conventional emulsion polymerization tech ⁇ niques. The resulting latex was filtered to remove any coagulum, and had 48 percent solids. To 100 wet grams of latex (45 percent solids), 4.5 g of propylene glycol phenyl ether were added, and mixed for at least 1 hour.
  • Sample 2 was identical to the above-described paper, except that it was made without the propylene glycol phenyl ether coalescing agent.
  • Sample 3 did not contain a coalescing agent and was made from a softer latex which was a blend of 40 percent of an 81 percent styrene, 17 percent 1,3- butadiene, 2 percent acrylic acid latex, and 60 percent of a latex comprising 49 percent styrene, 50 percent 1 ,3-butadiene, and 1 percent itaconic acid. The results are also shown below.

Abstract

Un procédé de préparation d'une feuille ayant une rigidité accrue consiste à mélanger une fibre, un latex présentant des conditions de formation de film minimales supérieures aux conditions qu'atteint la feuille pendant le séchage, ainsi qu'un agent coalescent fugitif. Le mélange est recueilli et séché dans des conditions inférieures aux conditions de formation de film minimales du latex. Ce procédé permet l'utilisation de latex durs, qui ne forment pas des films pendant le séchage de la feuille, les latex dur pouvant ainsi contribuer à la rigidité de la feuille finale. Une feuille préparée selon ledit procédé est également décrite.
PCT/US1987/002940 1982-12-23 1987-11-10 Feuilles de rigidite accrue constituees d'une fibre, de latex et d'un agent coalescent WO1989004398A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
KR1019890701275A KR890701841A (ko) 1982-12-23 1987-11-10 섬유, 라텍스 및 유합제로부터 제조된 강직성이 향상된 시트
JP50029288A JPH03502217A (ja) 1987-11-10 1987-11-10 繊維，ラテックス，及び融合助剤から作製される改良された剛性を有するシート

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US45258282A 1982-12-23 1982-12-23

Publications (1)

Publication Number Publication Date
WO1989004398A1 true WO1989004398A1 (fr) 1989-05-18

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Application Number Title Priority Date Filing Date
PCT/US1987/002940 WO1989004398A1 (fr) 1982-12-23 1987-11-10 Feuilles de rigidite accrue constituees d'une fibre, de latex et d'un agent coalescent

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KR (1) KR890701841A (fr)
AU (1) AU628285B2 (fr)
WO (1) WO1989004398A1 (fr)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4178205A (en) * 1977-08-17 1979-12-11 The Dow Chemical Company High strength non-woven fibrous material
US4225383A (en) * 1978-02-02 1980-09-30 The Dow Chemical Company Highly filled sheets and method of preparation thereof
US4246066A (en) * 1975-02-12 1981-01-20 Mitsubishi Paper Mills, Ltd. Method for producing fibrous sheet
US4426470A (en) * 1981-07-27 1984-01-17 The Dow Chemical Company Aqueous method of making reinforced composite material from latex, solid polymer and reinforcing material
US4445970A (en) * 1980-10-22 1984-05-01 Penntech Papers, Inc. High mineral composite fine paper

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4246066A (en) * 1975-02-12 1981-01-20 Mitsubishi Paper Mills, Ltd. Method for producing fibrous sheet
US4178205A (en) * 1977-08-17 1979-12-11 The Dow Chemical Company High strength non-woven fibrous material
US4225383A (en) * 1978-02-02 1980-09-30 The Dow Chemical Company Highly filled sheets and method of preparation thereof
US4445970A (en) * 1980-10-22 1984-05-01 Penntech Papers, Inc. High mineral composite fine paper
US4426470A (en) * 1981-07-27 1984-01-17 The Dow Chemical Company Aqueous method of making reinforced composite material from latex, solid polymer and reinforcing material

Also Published As

Publication number Publication date
KR890701841A (ko) 1989-12-21
AU8332887A (en) 1989-06-01
AU628285B2 (en) 1992-09-17

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