EP1623071A1

EP1623071A1 - Water-resistant, repulpable, hydrophilic and soft touch paper

Info

Publication number: EP1623071A1
Application number: EP04742393A
Authority: EP
Inventors: Gilles Lorentz; Ronald Hanks; Jean-Marc Pujol
Original assignee: Rhodia Chimie SAS
Current assignee: Rhodia Chimie SAS
Priority date: 2003-04-25
Filing date: 2004-03-30
Publication date: 2006-02-08
Also published as: FR2854175B1; FR2854175A1; JP2006525441A; WO2004097113A1

Abstract

The invention relates to absorbing paper, in particular a novel water-resistant, repulpable, hydrophilic and soft touch paper and to a method for the production thereof. The inventive paper is produced from a papermaking pulp consisting of an efficient quantity of at least one type of resin (A) improving damp strength and possibly at least one type of a damp resistance promoter (B) and is characterised in that said papermaking pulp or paper are brought into contact with a compound (D) comprising at least one type of polyorganosiloxane (C) which contains at least one siloxyl unit per molecule substituted by at least one functional group V which is directly linked to a silicium atom, said functional group V being a sterically hindered piperidinyl functional group.

Description

WATERPROOF, REPELLABLE, HYDROPHILIC AND SOFT TOUCH PAPER

The present invention relates to the field of absorbent papers and in particular a new water-resistant paper, repulpable, hydrophilic and with a soft touch, as well as a process for manufacturing this paper.

For certain paper applications, in particular for absorbent paper, it is necessary for the papers to retain in the wet state part of their resistance to dryness. The wet strength of the paper is generally expressed by the ratio: (wet LR / dry LR) x 100 where:

Wet LR is the breaking length of a strip of wet paper, Dry LR is the breaking length of a strip of dry paper. Generally speaking, wet-strength papers have a wet strength greater than 5%.

In order to improve the mechanical properties of wet paper, it is common practice at the papermaking stage to incorporate resins in the mass of the pulp in order to improve the wet strength of the paper. . For example, it is customary to use resins of the polyamido-amine epichlorohydrin (PAE) type, resins of low molecular weight, resulting from the condensation of adipic acid and of diethylenediamine followed by a reaction of the condensation product. on epichlorohydrin. This type of resin crosslinks on cellulosic fibers at neutral pH. These products are characterized by the presence of azetidinium type structures. To obtain papers which are even more resistant in the wet state, these resins have been combined with substances called wet resistance promoters such as polymers of anionic or amphoteric nature, for example, sodium carboxymethylcellulose (H. Espy, 1983 in Papermaker Research J., pp. 191-195), modified guar gum (patents CA 808,531 or US 5,318,669) or an anionic or amphoteric latex of acrylic polymer type (patent FR 2,769,926).

However, the use of resins in order to improve the wet resistance of the paper leads to a major drawback which is the loss of the feeling of softness to the touch because the paper becomes rougher. For applications in the field of absorbent paper, for example paper towels, toilet paper, etc., this loss of softness is a major obstacle to the marketing of the product in question. In addition, a paper made from this type of resin is difficult to repulp (or recyclable) which increases its manufacturing cost. In addition, ecologically it is desirable to generate a minimum of waste. The prior art represented by patent application JP-6311943 proposes treatment of the paper with a silicone emulsion based on diorganopolysiloxane comprising a specific group which is a linear aminoalkyl. However, the use of an amino silicone increases the water-repellency properties of the paper, which is detrimental for the hydrophilic properties of the paper. In addition, this type of paper is difficult to repulp. This solution is therefore not acceptable for absorbent papers.

The paper industry is therefore awaiting new solutions that make it possible to obtain absorbent or hydrophilic, repulpable papers, with a soft touch and resistant to water.

Now, the Applicant has unexpectedly found that a particular class of amino silicones has remarkable advantages over the other compounds known from the prior art. In fact, the applicant has developed a new water-resistant, repulpable, hydrophilic and soft-touch paper based on a class of cluttered amino silicones which do not have the drawbacks of the prior art cited above. . The Applicant has also developed a process for preparing this same paper.

It has therefore now been found, and this is what is the subject of the present invention, that it is now possible to obtain a paper resistant to water, repulpable, hydrophilic and with a soft touch.

The invention therefore relates to a new water-resistant, repulpable, hydrophilic and soft-touch paper prepared from a paper pulp, preferably a cellulose pulp, comprising an effective amount of at least one resin (A) improving the wet strength and optionally at least one wet strength promoter (B), characterized in that the paper pulp or the paper are brought into contact with a composition (D) comprising at least one polyorganosiloxane (C) comprising by molecule at least one siloxyl unit substituted by at least one functional group V directly linked to a silicon atom, the functional group V being a group with sterically hindered pipéπdinyle function (s) chosen from the group consisting of: - groups of formula (I): R ⁵ X ^

6

- R ⁴ - U - N - R

R5 R ⁵ d) formula in which:

• R ⁴ is a divalent hydrocarbon radical chosen from:

- linear or branched alkylene radicals, having 2 to 18 carbon atoms; - alkylene-carbonyl radicals, the linear or branched alkylene part of which contains 2 to 20 carbon atoms;

- alkylene-cyclohexylene radicals in which the linear or branched alkylene part contains 2 to 12 carbon atoms and the cyclo-hexylene part comprises an OH group and optionally 1 or 2 alkyl radicals having 1 to 4 carbon atoms;

- radicals of formula -R ⁷ - O - R ⁷ in which the identical or different radicals R ⁷ represent alkylene radicals having 1 to 12 carbon atoms;

- radicals of formula -R ⁷ - O - R ⁷ in which the radicals R ⁷ have the meanings indicated above and one of them or both are substituted by one or two group (s) -OH;

- radicals of formula -R ⁷ - COO - R ⁷ in which the radicals R ⁷ have the meanings indicated above;

the radicals of formula -R ⁸ -O -R ⁹ - O-CO-R ⁸ in which the radicals R ⁸ and R ^{9, which are} identical or different, represent alkylene radicals having 2 to

12 carbon atoms and the radical R ⁹ is optionally substituted by a hydroxyl radical;

• U represents -O- or -NR ¹⁰ -, R ¹⁰ being a radical chosen from a hydrogen atom, a linear or branched alkyl radical containing 1 to 6 carbon atoms and a divalent radical of formula:

in which R ⁴ has the meaning indicated above, R ⁵ and R ⁶ have the meanings indicated below and R ¹¹ represents a divalent alkylene radical, linear or branched, having from 1 to 12 carbon atoms, one of the valential bonds (that of R ¹¹ ) being connected to the atom of -NR ¹⁰ -, the other (that of R4) being connected to a atom of silicon;

• the radicals R ⁵ are identical or different, chosen from linear or branched alkyl radicals having 1 to 3 carbon atoms and the phenyl radical; and

• the radical R ⁶ represents a hydrogen radical, the radical R ⁵ or O ^* ; and

groups of formula (II)

R ⁵

R '- ^. - U ' ^X N -R ⁶ i

J (N) formula in which: • R ' ⁴ is chosen from:

- a trivalent radical of formula

_ where m represents a number from 2 to 20, and a trivalent radical of formula:

where p represents a number from 2 to 20; • U 'represents -O- or NR ¹² -, R ¹² being a radical chosen from a hydrogen atom, a linear or branched alkyl radical containing 1 to 6 carbon atoms; and • R ⁵ and R ⁶ have the same meanings as those given with regard to formula (I).

According to the present invention, by "effective amount of at least one resin (A) improving the wet strength and optionally of at least one wet strength promoter (B)" means the amount necessary and sufficient to obtain the desired effect. The amount will vary depending on the type of paper (absorbent, super absorbent, etc.), for example useful quantities of resin (A) and of wet resistance promoter (B) according to the invention, expressed as dry matter relative to to the dry fiber mass of paper, are generally between 0.01 and 5%. However, this ratio can be varied beyond this interval if necessary.

Advantageously, the polyorganosiloxane (C) is composed of the siloxyl units represented by the formula (III):

formula in which:

(1) the symbols Z, identical or different, represent R ¹ , and / or V;

(2) the symbols R ¹ , R ² and R ³ , identical and / or different, each represent an alkyl radical in C Cι ₂ , linear or branched, optionally substituted, a cycloalkyl radical in C5-C ₁₀ , optionally substituted, a aryl radical in Cβ-C-is, optionally substituted, an aralkyl radical, optionally substituted or a radical -OR ¹³ where R ¹³ represents a hydrogen, an alkyl radical, linear, branched or cyclic, having from 1 to 15 carbon atoms and a hydrόcarbon group comprising an epoxy and / or polyether function;

(3) the symbols V having the same definition as above; and

(4) - the number of siloxy units without group V is between 1 and 800,

- The number of siloxy units with a group V is between 1 and 20, and - 0 <w <_10 and 8 <y <798.

According to a preferred embodiment, the polyorganosiloxane (C) of formula (III) is linear (w = 0) and the symbols R ¹ , R ² and R ³ of formula (III) are methyl groups.

According to another preferred mode, the functional groups V of the polyorganosiloxane (C) are defined by the formulas (I) and (II) in which the groups R ⁵ are methyl.

More specifically, the polyorganosiloxane (C) according to the invention is a compound of general formula (IV) below: (CH ₃ ) ₃ -s 0- Si - (CH _â 3) '. 3

(IV) formula in which: the different patterns are distributed statistically in the chain; p represents a number greater than or equal to 0; r represents a number greater than or equal to "0; q represents a number greater than or equal to 1, preferably between 1 and 20;

R ' ¹ represents an alkyl radical, linear or branched, having 1 to 18 carbon atoms; the groups U, R and R have the same definition as above.

According to a preferred mode, the sum p + r is between 1 and 800.

Among the resins (A) improving the useful wet strength according to the invention, mention may in particular cationic polyamidoamine epichlorohydrin (PAE) resins or cationic resins of polyamide Amres mark (eg resins Amres ^® 2747, Amres® 8855, Amres® 8870, Amres® HS-30, Amres ^® HP-25, Amres ^® MOC- 3066, Amres ^® LA 12-2, Amres ^® C12, Amres ^® C20, Amres ^® C25, Amres ^® C28, Amres ^® X-184, Amres ^® C382, Amres® PR-335 CU, Amres® PR-247 HV and Amres® LOPR) sold by the company Georgia-Pacific Résines. Other resins are described in US Patents 3,372,086; US 3,607,622, US 3,914,155, US 4,233,411, US 3,556,932, US 3,734,977, US 4,722,964 and US 5,567,798.

Preferably, the resin (A) improving the wet strength is chosen from the group consisting of cationic resins of the polyamido-amine epichlorohydrin type.

Among the wet resistance promoters (B) useful according to the invention, mention may be made of polymers of anionic or amphoteric nature such as sodium carboxymethylcellulose described in the article by H. Espy, 1983 in Papermaker Research J., pp. 191-195), modified guar gum (described in patents CA 808,531 or US 5,318,669) and an anionic or amphoteric latex of acrylic polymer type (described in patent FR 2,769,926). The composition (D) containing the polyorganosiloxane (C) can be prepared in many forms: liquid, gaseous or solid. In the case of a liquid preparation of the composition, the latter will advantageously be aqueous, either in the form of a solution, dispersion or emulsion. Preferably, the composition is prepared in the form of an aqueous emulsion. The paper is either impregnated with this composition or it is either added to the paper pulp or is applied to the paper during the papermaking process.

The aqueous emulsions are generally based on a mixture of oil and water, and are prepared according to conventional methods well known to those skilled in the art using surfactants. For example, the emulsions can be made by the so-called direct methods or by inversion. Their realization is easy and does not require the use of high speed agitation equipment. Apparatus at normal stirring speed may be used.

In general, the aqueous emulsions prepared in accordance with the invention preferably contain between 20 and 90% by weight of water relative to the total mass of the constituents of the emulsion. For better application when the composition is applied to paper. These emulsions are found to be stable at room temperature.

The application to composition of composition (D) according to the invention can be carried out in very diverse forms. The applications can be carried out by immersion, coating, spraying, printing, "padding", or by any other existing means.

The quantity of polyorganosiloxane (C) deposited on the paper to be treated or added to the paper pulp varies according to the constitution and the type of paper. In general, the best results have been observed with an amount of polyorganosiloxane of between 0.1 and 10% by weight relative to the weight of the dry matter to be treated.

The polyorganosiloxanes (C) previously defined can be prepared according to different methods; for example: by redistribution or by a hydrosilylation reaction (see for example patent EP 388,321).

The present invention also relates to a process for manufacturing a water-resistant, repulpable, hydrophilic and soft-touch paper in which a paper pulp, preferably a cellulose pulp, is prepared, comprising an effective amount of at least one resin (A) improving the wet strength and optionally at least one wet strength promoter (B) characterized in that the paper pulp. or the paper are brought into contact with a composition comprising at least one polyorganosiloxane (C) such as defined above. The advantage of this process is that it makes water-repellable, repulpable, hydrophilic and soft-touch paper. Another advantage associated with this process is the possibility of easily plumping the waste thus lowering production costs.

Examples of wet strength improving resin (A) useful according to the process of the invention are as described above.

Preferably, the resin (A) improving the wet strength is chosen from the group consisting of cationic resins of the polyamido-amine epichlorohydrin (PAE) type.

By way of illustration, the process for manufacturing paper according to the invention can be described by steps a) to f) which, apart from the use of the composition (D) according to the invention, are known per se to man of the trade and can be summarized as follows: a) The paper pulp is suspended in water inside "pulpers" to separate the fibers. After purification, the pulp undergoes a so-called "refining" operation, which aims to hydrate the fibers, so as to allow them to become entangled. It is then that the mineral fillers (carbonate of calcium, kaolin, talc, titanium dioxide) and the adjuvants (glues, retention agents, antifoam, antislimes, dyes, shaders, brighteners, etc.), which will improve the characteristics of the paper. it is at this first stage that the composition (D) according to the invention can be added to the paper pulp. b) The pulp is again purified, then diluted and deaerated. Then, the pulp is distributed in the form of "jet" over the entire width of a canvas of a mechanical assembly called a "training table". This canvas is subjected to a jerky back and forth movement which facilitates the homogeneous formation of the sheet of paper and its the fibers naturally tend to get line themselves in the direction of movement of the dough stream. The sheet of paper contains 75 to 85% water when it leaves the "table". c) In this step, the percentage of water in the paper sheet is reduced to 60 or 70% by the pressing technique which also makes it possible to increase the compactness and improve the surface condition by mechanical action on the leaf still very malleable. d) Then the sheet of paper is dried by means of cast iron drums heated internally with steam. e) Optionally, a step of coating or "coating" the sheet of paper is carried out. The paper is coated with a composition based on starch and possibly other materials such as, mineral pigments (carbonate, talc ...), dyes, brighteners, shaders and dispersants. f) Optionally, the surface of the paper can be leveled off using polished steel rollers. The paper thus treated undergoes an equalization of its surface, by compression: it is said "primed" or "satin".

According to a second variant of the process, the paper can be treated with the composition (D) according to the invention after steps d), e) and / or f).

The present invention also relates to the use of the composition (D) comprising at least one polyorganosiloxane (C) comprising, per molecule, at least one siloxyl unit substituted by at least one functional group V directly linked to a silicon atom in the manufacture , wet, of a paper resistant to water, repulpable, hydrophilic and to the soft touch.

The present invention is particularly suitable for applications such as paper towels, toilet paper, household absorbent or hygienic paper, tissues or any other paper requiring good absorbent properties, good mechanical resistance to , good repulping ability and a soft touch.

The following examples are given by way of illustration and cannot be considered as limiting the scope of the invention.

EXAMPLES

The examples below illustrate the properties of the compositions comprising the polyorganosiloxanes according to the invention.

The papers used are as follows: - hand towel (small roll);

- laboratory paper towel (large roll); and

- paper napkin.

The paper processing technique used for the tests is the padding impregnation technique. For this, the polyorganosiloxanes are applied in the aqueous phase. The dilution of the emulsions is calculated so as to deposit 1% of dry silicone on the paper.

The polyorganosiloxanes are tested in application in the form of an aqueous emulsion and the measurements of hydrophilicity and evaluation of the feel are carried out according to the tests described below. Touch test.

After impregnation of the emulsion, the paper is dried by a heat treatment for 3 minutes at 150 ° C, and is placed in conditioning for 24 hours (23 ± 2 ° C, 60% ± 5% relative humidity). The softness is assessed by a group of testers who are asked to classify the paper samples from the roughest (minimum score = 1) to the softest (maximum score = total number of samples).

Hydrophilicity measurement. The hydrophilicity measurements are given by the TEGEWA test in which the absorption time of a drop of water deposited on the surface of the paper is measured. The shorter the time, the more hydrophilic the paper.

Preparation of emulsions. The silicone oils of the emulsions tested E1 and E2 (invention) have the structure:

Emulsion E1: x = 10 and y = 700

Emulsion E2: x = 2 and y = 100. The emulsion C1 (comparative) is an emulsion based on silicone oil functionalized by a linear amino function of structure: Me ₃ SιO (iOMe) ySiMe ₃

NH -

with x = 1, 5 and y = 135.

The emulsions are prepared using a method of emulsification by inversion, and have the following composition: 20 g of tested silicone oil, 8 g of surfactant (fatty alcohol C13E6), an amount of glacial acetic acid stoichiometrically necessary to neutralize the amine and the complement to 100g with water.

Results.

Claims

CLAIMS 1 - Water-resistant, repulpable, hydrophilic and soft-touch paper prepared from a paper pulp comprising an effective quantity of at least one resin (A) improving wet strength and optionally at least one wet strength promoter (B), characterized in that the paper pulp or paper is brought into contact with a composition (D) comprising at least one polyorganosiloxane (C) comprising per molecule at least one siloxyl unit substituted by at least one functional group V directly linked to a silicon atom, the functional group V being a group with sterically hindered piperidinyl function(s) chosen from the group consisting of: - groups of formula (I): formula in which : • R4 is a divalent hydrocarbon radical chosen from: - linear or branched alkylene radicals, having 2 to 18 carbon atoms; - alkylene-carbonyl radicals whose linear or branched alkylene part contains 2 to 20 carbon atoms; - alkylene-cyclohexylene radicals of which the linear or branched alkylene part contains 2 to 12 carbon atoms and the cyclo-hexylene part contains an OH group and optionally 1 or 2 alkyl radicals having 1 to 4 carbon atoms; - the radicals of formula -R7 - O - R7 in which the identical or different R7 radicals represent alkylene radicals having 1 to 12 carbon atoms; - the radicals of formula -R7 - O - R7 in which the radicals R7 have the meanings indicated above and one or both of them are substituted by one or two -OH group(s); - the radicals of formula -R7 - COO - R7 in which the radicals R7 have the meanings indicated above; - the radicals of formula -R8 -O -R9 - O-CO-R8 in which the identical or different radicals R8 and R9 represent alkylene radicals having 2 to 12 carbon atoms and the radical R is optionally substituted by a hydroxyl radical ; U represents -O- or -NR10-, R10 being a radical chosen from a hydrogen atom, a linear or branched alkyl radical containing 1 to 6 carbon atoms and a divalent radical of formula: R^ 11 RNN - RR^ R 'in which R has the meaning indicated above, R and R have the meanings indicated below and R11 represents a divalent alkylene radical, linear or branched, having from 1 to 12 carbon atoms, one of the valent bonds (that of R11) being connected to the -NR10- atom, the other (that of R4) being connected to a silicon atom; • the R5 radicals are identical or different, chosen from linear or branched alkyl radicals having 1 to 3 carbon atoms and the phenyl radical; and • the radical R6 represents a hydrogen radical, the radical R5 or O*; and groups of formula (II) formula in which: • R'4 is chosen from: - a trivalent ical radical of formula / -(CH2) CH m CO where m represents a number from 2 to 20, and a trivalent radical of formula: N (CH2 NH N where p represents a number from 2 to 20; • U' represents -O- or NR12-, R12 being a radical chosen from a hydrogen atom, a linear or branched alkyl radical comprising 1 to 6 carbon atoms; and • R5 and R6 have the same meanings as those given in connection with formula (I). 2 - Water-resistant, repulpable, hydrophilic and soft-touch paper according to claim 1 characterized in that the polyorganosiloxane (C) is composed of siloxyl units represented by formula (III): formula in which:

(1) the symbols Z, identical or different, represent R ¹ , and/or V;

(2) the symbols R ¹ , R ² and R ³ , identical and/or different, each represent a C-ι-Cι ₂ alkyl radical, linear or branched, preferably methyl, optionally substituted, a C ₅ cycloalkyl radical -C ₁₀ , optionally substituted, a C ₆ -C ₁₈ aryl radical, optionally substituted, an aralkyl radical, optionally substituted or an -OR ¹³ radical where R ¹³ represents hydrogen, an alkyl radical, linear or branched, having 1 with 15 carbon atoms and a hydrocarbon group comprising an epoxy or polyether function;

(3) the symbols V having the same definition as in claim 1; And

(4) the number of siloxyl units without a V group is between 1 and 800, the number of siloxyl units with a V group is between 1 and 20, and

0 < w <_10 and 8 < y <798. 3 - Water-resistant, repulpable, hydrophilic and soft-touch paper according to claim 2 characterized in that the polyorganosiloxane (C) is defined by formula (III) in which w=0 and the radicals R ¹ , R ² and R ³ are methyl groups.

4 - Water-resistant, repulpable, hydrophilic and soft-touch paper according to claim 1 characterized in that the functional groups V of the polyorganosiloxane (C) are defined by said formulas (I) and (II) in which the groups R ⁵ are methyls.

5 - Water-resistant, repulpable, hydrophilic and soft-touch paper according to claim 1 characterized in that the resin (A) improving wet strength is chosen from the group consisting of cationic resins of the polyamido-amine epichlorohydrin (PAE) type ).

6 - Water-resistant, repulpable, hydrophilic and soft-touch paper according to claim 1 characterized in that the paper pulp is a cellulosic pulp.

7 - Process for manufacturing a water-resistant, repulpable, hydrophilic and soft-touch paper in which a paper pulp is prepared comprising an effective quantity of at least one resin (A) improving wet strength and optionally d 'at least one wet strength promoter (B) characterized in that the pulp or paper is brought into contact with a composition comprising at least one polyorganosiloxane (C) defined according to one of claims 1 to 4.

8- Process for manufacturing a water-resistant, repulpable, hydrophilic and soft-touch paper according to claim 7 characterized in that the resin (A) improving wet strength is chosen from the group consisting of cationic resins of the type polyamido-amine epichlorohydrin.

9- Process for manufacturing a water-resistant, repulpable, hydrophilic and soft-touch paper according to claim 7 characterized in that the paper pulp is a cellulosic pulp.

10 - Use of the composition (D) according to claim 1 comprising at least one polyorganosiloxane (C) comprising per molecule at least one siloxyl unit substituted by at least one functional group V according to claims 1 to 4 directly linked to a silicon atom in the wet manufacturing of water-resistant, repulpable, hydrophilic and soft-touch paper.