DE7629460U1 - REFINED PAPER SHEET - Google Patents

Description

Papers of different densities are made for the most diverse Uses used. Papers with a low density are soft and porous and white have great absorbency unless they are treated to reduce absorbency, Papers with a medium density are used as writing papers, printing papers, wrapping papers, as well as paper bags and display papers. High density papers include glossy papers, greaseproof papers, vegetable parchment papers, vulcanized fiber papers and highly calendered papers.

An example of a medium density writing paper is described in U.S. Patent 3,839,144. Although this, paper has good tightness and excellent properties

9
1 7230/01 / Ch / Fr • • • · ·· ··· • • ·· •
M. ·· • · • 9 β
... φ - 2nd • 10. ·· Sep

has shafts in terms of non-fat permeability, also has good resistance to erasure, other properties are disadvantageous. For example, this paper is not cheap to produce because it is made from a paper pulp that consists of up to one A certain Schopper-Riegler degree of freedom consists of highly refined pulp, which contains certain amounts of unrefined pulp Pulp can be added. The paper pulp can also consist of a mixture of alpha or cotton pulp with an ordinary pulp, the mixture being highly refined before the paper pulp is fed to the wire of the paper machine. It has been shown that the drainage of water in such highly refined paper pulps is relatively difficult, so that it is difficult.

to produce with the desired tightness. Hence, this paper is more expensive to manufacture than it is to manufacture a common paper. Furthermore, there is a limit to the maximum thickness of such paper and the The need to refine the pulp further increases the cost of manufacturing such paper.

Such papers, however, have a number of desirable properties. For example, you have one high tensile and breaking strength (measured according to Mullen), improved folding strength, improved fiber composite, improved properties with regard to fiber detachment, they are resistant to the penetration of solvents and oil, have high abrasion resistance and are relatively stiff. On the other hand, these point Papers have a low tensile strength, are relatively brittle, their dimensional stability leaves something to be desired and the

7230/01 / Ch / Fr - 3 - 10 September 1976

Aging properties are not good. In addition, there are the previously mentioned high manufacturing costs. For example, vegetable parchment papers and papers which are produced by the so-called fiber vulcanization process, relatively low tensile strength at im Compared to high-calendered papers of medium density.

Papers with a relatively low density are impregnated with a polymer resin. Before impregnation, these papers have a tightness that, expressed in weight per millimeter of thickness (based on 500 sheets of 610 915 mm), is usually between 107.28 to 125.16 kg / mm down to QQ-U kg / ιρΐϋ -s after impregnation

Resin is 50 % of the weight of the paper, calculated on a dry basis. As a result of the porosity and the low density, such a paper is not suitable for use as erasable writing paper. In addition, its resistance to solvents is poor.

The polymer resins which are used for coating and impregnating such papers with low density are by nature relatively soft and elastic and therefore differ from the hard and inelastic polymer resins. The thermal glass transition temperature (Tg) is a measure of the stiffness or the film stiffness of the polymer resin. This is the temperature that corresponds to the temperature at which the resin forms a continuous film. For example, the glass transition temperature of a relatively soft and elastic polymer resin is below ⁰ ° C. In contrast, stiff and inelastic polymers have melt temperatures of more than 15 ° C. ■ "- '* ■. I"

ir
■ 't

7230/01 / Ch / Fr - 4 - 10 September 1976

Papers of 143 kg / mm or greater that have been impregnated with a relatively stiff polymer material have certain desirable properties. Such papers are, for example, better with regard to their tensile strength and breaking strength, with regard to their abrasion resistance, with regard to the resistance to fiber detachment and with regard to the resistance to the penetration of solvents and grease. In addition, they have good folding resistance. On the other hand, papers of this type have certain undesirable properties which make them appear unsuitable for use as writing paper. Such undesirable properties are, for example, poor tensile strength, poor writing quality and increased brittleness. Since such papers do not absorb the same amount of impregnating agents as the aforementioned porous papers, it is generally assumed that the improvement in the physical properties of the paper as a result of impregnation can only be achieved if the paper is porous and the resin content of the finished paper is 50 %. exceeds its weight.

Experiments have shown that the tightness of a paper before it is impregnated and the proportion of resin impregnated in the paper influence the reduction in tear strength when the paper is impregnated with a rigid polymer. For example, papers with various initial densities have been impregnated with an aqueous dispersion of a hard polymeric polyvinyl acetate resin (PVAC), as sold under the trade name VINAC by Air Products and Chemical Co. of Allentovm, Pa. The dispersion contained AO wt.% VINAC 880. The impregnation was effected by the Einbauchen Blät-

S.

• ■ · Α »· 1 · ·

7230/01 / Ch / Fr

September 10, 1976

ter into the aqueous dispersion, which were then passed through nip rollers to remove the excess impregnating agent to remove. The leaves were then placed in a Williams paper dryer for 4 minutes each 115 ° C dried for 2 minutes each side. After the papers were conditioned for several days, their weight, their thickness and ultimately their tensile strength measured before and after impregnation. The results were as follows:

example

original tightness
(kg / mm)

PVAC in the sheet (#)

Tightness
impregnated

Change in tensile strength (96)

A. B. C. D. E.

98.34 146.6 155.5 166.3 175.2

48.5 96

41.5 96

38.6 96 42.1 96 30.1 96

162.7 Increase 20 96 228.9 Decrease 33 % 216.3 Decrease 43 96 244.9 Decrease 37 96

237.8 Acceptance 25 96

From the above table it can be seen that _/ when the paper is impregnated with a hard polymeric material, there is a significant decrease in tensile strength. This is particularly unfavorable because the other properties of the paper, such as tensile and breaking strength, abrasion resistance and resistance to fiber peeling always reached their maximum values.

7629480 2UM7

«■ (-» .- - 'ί J ^ l * , L „- —JT— ™ ■ r

¹ ·% »ι, ■. , ι I- ς- ^ 1

kV

7230/01 / Ch / Fr - 6-10 September 1976.

position of a glossy paper.

The object is therefore to create a finished paper which has the desired physical properties, in particular improved tensile strength and lower brittleness. It should open a paper machine at a relatively high speed. In addition to the aforementioned improved tensile strength and lower brittleness should the paper be resistant to Ul and Solvents, as well as a high resistance to abrasion and folding. Fold resistance is the fatigue strength of the paper when it is folded. The paper should be used in particular as a cover or Cover paper for books and air paper carrier for self-adhesive strips. The invention further comprises a improved manufacturing process for making these papers.

In particular, there is therefore the task of creating a paper which can be produced cheaply and which is impregnated with a sufficient amount of a hard polymeric material is so that it is resistant to oil and solvents without affecting the tensile strength and the abrasion resistance is significantly impaired will" .

7 «2t * 6Ö 2413.77

US Pat. No. 3,634,298 describes a coating material for paper. The coating material comprises a Härtpolymer (with a Zerfließteiaperatur (Tg) in the range of about 30 ⁰ C to 45 ° C), which was mixed .ait sound; porridge. This mixture was applied to the paper web to produce

7230/01 / Ch / Fr - 7-10 September 1976

In the paper according to the present invention, most of the disadvantages when impregnating with a Hard polymer occur, avoided, the paper has an improved folding time resistance, resistance to oil is excellent, good tensile strength properties and resistance to breakage properties are present and at which further resistance to solvent penetration and the abrasion resistance is improved. For this purpose, the invention proposes a paper impregnate to an uncalendered dry density of preferably about 125 to 200 kg / mm (7-11 lbs / mil) with a liquid dispersion, which consists essentially of a hard polymer material and a mineral filler, which are mixed with one another in predetermined proportions. In the present Description was the weight per 1/1000 target Thickness corresponds to 1 lbs / mil converted into kg / mm with a factor of 17.88. So this means that 1 lbs / mil is about Corresponds to 17.88 kg / mm.

The impregnation material is dispersed through the entire thickness of the paper, the proportion of the impregnation material preferably being between 8.5 and 50 %, preferably between 15 and 40 % of the end product. The filler material is in a range between 10 to 65% by weight of the impregnation material, preferably the filler material is in a range between 20 and 65 %. The hard polymer has a hardness and film hardness, which is determined by a Zerlauftemperatür between 15 to 60 ⁰ C, preferably this transition temperature is 22-44 ⁰ C. The polymer material

γ; - '.- ■; ■ -. - ■ y ■.

"'

7230/01 / Ch / Fr - 8-10 September 1976

preferably made of polyvinyl acetate, polyacrylate, polyvinyl chloride, Homo- and copolymers and mixtures thereof. The preferably inorganic fillers include clay, Calcium carbonate, mica, talc and mixed days thereof.

The paper according to the present invention having a final density in the uncalendered state of preferred 187.7 to 250 kg / rjn (10.5 to 14 lbs / mil) at 500 sheets of size 610 χ 915 mm has certain properties that impregnated paper does not were to be expected. For example, if the paper is impregnated with a stretched hard polymer, then his Folding fatigue strength is far better than that exhibited by a paper that is only coated with a hard polymer was impregnated. Impregnation with a hard polymer would normally reduce the tensile strength of the paper decrease considerably. If, on the other hand, the paper is impregnated according to the present invention, results the surprising effect that the tensile strength is essentially retained while at the same time the paper has excellent oil repellent properties. By using an impregnating agent, which contains a substantial proportion of fillers, the production costs of the paper are reduced by reducing the total amount of polymer required to achieve the desired properties which means that the higher cost of the polymer is replaced by the lower cost of the filler.

It is desirable that the impregnation takes place at one point at the beginning of the paper machine, for example a Fourdrinier machine is used,

7629460 240177

/ β

7230/01 / Ch / Fr - 9-10 September 1976

in which the cellulose paper pulp is placed on a wire mesh web, in which the paper pulp to a web is formed before it leaves the wire mesh web and is then dried. The impregnation should take place after the paper web has formed and becomes coherent and at the latest before this paper web has partially dried. The paper web However, it can also be impregnated after the paper has completely dried and rolled, i.e. H. the impregnation is carried out as a separate process step after the production of the paper. Preferably will the paper web is impregnated in the calibration roll of a conventional paper machine. It is desirable for that Tightness of the paper that this is controlled in

U ^ _. K_ ~ ^ ««. * 3._A - ρ ■■ JX ^. * ^ T— ■, we t ,, tn * * wt η J4a T \ 4 *% W

nci3C | SW uaD vux ucrx IB (U agiuci U115 uxc v ^ wu aea iixcuu iuu.aiiui ° xei't.ea u'wncucu raj / ici β Iw oc—

ranges from 125 to 200 kg / mm (7 to 11 lbs / mil) and preferably between 150 to 187 kg / mm (8.5 to 10.5 lbs / mil). The paper web passes through an aqueous dispersion therethrough which preferably from 12.5 to 60% ₉ in particular from 12.5 to 40 wt%. # Contains the impregnant. After the impregnation, the paper web is heated so that the impregnating agent melts in the paper web. The impregnating agent can also be mixed with the paper pulp in the mixer before the paper pulp is applied to the wire mesh web.

According to a preferred method, this comprises the following steps: The paper web with a Tightness in the dry, uncalendered state between opposing surfaces in the range between 125 and 200 kg / mm is impregnated during passage by applying an aqueous dispersion to both

- 10 -

"• ^s ill ι JJ

7230/01 / Ch / Fr - 10-10 September 1976

Surfaces, this dispersion having a hard polymer and an inorganic filler. The impregnation compound consists essentially of 35 to 90 % of a polymer and 10 to 65 % of an organic filler, these percentages being based on the weight of the impregnation compound. The hard polymer reaches the film formation at a temperature ranging between 15 and 60 ⁰ C. After the application of the impregnating agent on both sides of the web passes this through a squeeze roller pair, which ensures the penetration of the dispersion into the paper web, and wherein the excess dispersion from the surfaces Will get removed. After leaving this pair of nip rollers and after removing the excess dispersion, heating takes place for the purpose of ■ melting the dispersion in the paper web,

(The impregnation compound then based on the xrocKen weight of the paper web is between 8.5 and 50 % .

The polymeric material used in its manufacture must have a certain minimum hardness, d. H. a certain brittleness or film stiffness, which is determined by the temperature at which the polymeric material forms a film, this temperature Tg must be greater than 15 °. Hard polymers which have these properties are, for example, a polyvinyl acetate copolymer as it is called RESYN 1105 and 1255 from National Starch and Chemical Corp. in New York, VINAC 880 Monopolymer as manufactured by Air Products and Chemical Co. of Allentown, Pa. Suitable polyacrylics are RHOPLEX AC 201 and TR 407 manufactured by Rohm and Haas Company of Philadelphia, Pa. A suitable one

Ι-ΖΪ? · "■ '" ■ · ■■' · ■

7230/01 / Ch / Fr - 11-10 September 1976

Polyvinyl chloride 1st GEON 351 »manufactured by B.F. Goodrich Chemical Company of Akron, Ohio. Each of the aforementioned polymeric materials is used as is commercially available for the papermaking processes. It should be noted that the polymeric substances can consist of copolymers, which may have a certain proportion of other polymers or mixtures thereof. However, care must be taken to ensure that the temperature at which film formation occurs, is located in the aforementioned area.

The inorganic fillers with which the hard polymers are mixed to create an aqueous dispersion, consist preferably of a fine-powdered mineral filler, as it is commercially available in paper manufacture

XBb. jjxct iciivueugruoe ueo ruxiBiiUiieo duiiub xiu ουιοχυΐι between 2 to? Hikron lie. Examples of Füxxslux— Fences that have been used in a trial and give good results are kaolin clay, calcium carbonate, mica and talk.

The proportion of impregnation in the end product must be within a certain range. The proportion of the impregnating agent should preferably be between 8.5 % and 50% by weight, based on the total weight of the paper in the dry state. If the proportion of the impregnation compound is below this lower limit, then the paper has poor abrasion resistance. However, due to the tightness limits of the starting paper, it is difficult to carry out an impregnation below this lower limit. The proportion by weight of the impregnation compound is preferably in a range from about 15 % to about 40 %. The uncalendered final density of the impregnated paper should preferably be between 188 and 250 kg / mm

: .-; ■■ - 12 -

7829460 -2 UM »

7230/01 / Ch / Fr - 12-10 September 1976

(10.5 to 14.0 lbs / mil) is 500 sheets that are 610 χ 914 mm in size.

In order for the paper to have the desired properties, it is necessary that the hard polymeric material is stretched within the prescribed limits with at least one of the aforementioned mineral fillers. The filler should be about 10% to about 65 % of the solids weight of the impregnation compound. The filler material should preferably be in the range between 20 and 65% by weight of the impregnation compound. The residual weight of the impregnating composition is made of hard resin so that the resin content of 35-90, preferably between 35 and 80 wt.% Of the impregnating composition. It has been shown that if the proportion of filling compound reads below the lower limit. the tear strength of the paper decreases considerably. On the other hand, if the proportion of filler is above the upper limit, the resistance of the paper to oil and solvents decreases and the resulting paper tends to shrink.

The paper according to the present invention is made on a conventional paper machine, such as for example a Fourdrinier machine. At a In such a machine, the paper pulp is placed on a moving wire mesh track and after a paper pulp tape is created, this tape leaves the wire web and is dried over a series of heating rollers of the paper tape. It is customary that the paper ba ^ d, when it is at least partially dried, is subjected to further treatments, such as one Gluing treatment by a glue roller, which is arranged in front of the heating rollers.

78294B0

7230/01 / Ch / Fr - 13-10 September 1976

In making the paper according to the present invention, it is desirable that the impregnation take place after the paper has become coherent and at least is partially dry and in a state in which the paper is essentially free of glue. Preferably the impregnation takes place at the glue roller, but the impregnation can also take place at a later point in papermaking. It is known that two different types of glue rolls are used in papermaking Find use. Either of these two different ways is suitable for carrying out the impregnation of the paper. So-called haizontal glue rollers and so-called vertical glue rollers are used. With horizontal Glue rollers are two opposite rollers rotatably arranged, with their axes a horizontal distance have to each other. The paper web runs down between the rollers, pressure being applied to opposite sides of the paper web. The impregnation liquid forms a sump between each side the paper web. In the case of a vertical glue roller arrangement, the rollers are arranged with a vertical distance between the axes and the paper web moves horizontally between the rollers. The lower roller is connected to a trough, from where the roller the impregnation compound is taken up and applied to the underside of the paper web. On top of the The impregnating compound is applied to the paper web, for example from a reservoir to the paper web is pumped. In both cases the linear surface pressure between the rollers is 22.5 to 112.5 kg. as a result This pressure between the rollers presses the impregnating compound into the paper web, while the excess impregnating barrel is removed from the paper web will.

- 14 -

7230/01 / Ch / Fr, - 14- _ '\. September 10 ^ 976

It doesn’t matter at which stage of the papermaking process the impregnation is carried out, so it is important that the resin-filler mixture through the whole Thickness of the paper web is dispersed in order that the full advantages of the present invention are realized <= * n be able. The advantages are not achieved if the impregnation compound is only present as a coating on the surface of the paper web, as is the case, for example is the case with the subject matter of U.S. Patent 3,634,298. at This system rotates our periphery one Roller In a trough that contains the coating compound, while the top periphery with the bottom the moving paper web is in contact. To this This roller takes up the coating compound and transfers it to the underside of the paper web. the The thickness of the coating is controlled by moving the coated paper web over a doctor blade, which only leaves a certain amount of the coating compound on the underside of the paper web.

It is also possible to mix the impregnating compound with the paper pulp before it reaches the wire mesh web.

In order to be sure that the impregnation composition disperses through the entire paper web, it is desirable that certain conditions be observed during the manufacturing process. For example, before impregnation, the density of the dry, uncalendered paper web should preferably be in the range between 125 to 200 kg / am. This tightness can be met by a number of known ones. Measures ₀ The maintenance of this tightness before impregnation is of

- 15 -

a * • aa »A • «right a a
a
at * a
»N · «A »T a a.

7230/01 / Ch / Fr - 15-10 September 1976

This is important because if the density is less than 125 kg / mm, the resulting paper can be too porous. Is against it the tightness above 200 kg / mm, then it may be that the paper web is not able to provide sufficient Take up quantities of the impregnation compound so that the desired properties arise.

Another important step in the manufacture of the paper of the present invention is the desirably precise adjustment of the solids content of the aqueous dispersion through which the paper web is passed. For example, the solids content should preferably be in the range between 12.5 to 60 % of the total weight of the dispersion, with the remaining weight percentage consisting of hard polymeric material. If the percentage by weight is below the lower limit, there is a risk that a paper in the above-mentioned density range will not take up a sufficient percentage of the impregnation folder to produce the desired results. If, on the other hand, the percentage is above the above-mentioned upper limit, there is a risk that the dispersion will become viscous and the resin-filler-impregnating compound tends to coat the surface of the paper web, this paper web surface then having a density of close to 200 kg / mm, however the inside of the paper web is not sufficiently impregnated.

After impregnation, the paper web is heated so that the impregnation compound in the paper melts. In conventional paper production, the paper web is heated to a temperature of 100 ^° C., with the paper web

- 16 -

7230/01 / Ch / Fr - 16-10 September 1976

dries, but hard polymeric materials would be used, whose melting temperature is above this temperature, then unsatisfactory results would be obtained will. The melting temperature of the hard polymeric material is therefore preferably in accordance with the present invention at a maximum of 60 °.

Certain advantages are realized in papermaking according to this process. For example, avoids a hard polymer impregnation compound that is heavily stretched with a filler, the adhesiveness the impregnation compound, so that the heating rollers are much easier to clean.

Some examples are given below. Examples I and II illustrate the preferred level the addition of a mineral filler to the hard polymer material. In example III the tightness the hardness of the polymer. Materials clarifies: Cheap types of fillers which produce satisfactory results are covered in Example IV. Example V explains the importance of the tightness of the paper clarified before impregnation. The proportion of the impregnation compound to produce the desired properties of the Paper is clear from Example VI. Different types of hard polymeric material are in the example VII dealt with. Example VIII illustrates the abrasion resistances of the paper according to the present invention. Example IX illustrates the properties of the paper according to the invention in comparison with a paper which only coated but not impregnated.

- 17 -

7230/01 / Ch / Fr - 17 - 10 September 1976

Example I.

In order to determine the permissible limits for adding a mineral filler to the resin, unsized paper was used, which was made from 50 % bleached hardwood paper fibers and 50% bleached Northern paper fibers. The starting weight of this paper was 23.3 kg, which means the weight of 500 sheets of the size of 610 × 915 mm. The thickness of the sheets was 0.14 mm. The density of the starting paper was approximately 168 kg / mm. The impregnation compound was prepared by dispersing finely ground calcium carbonate having a particle size of about 2 microns in water with constant stirring. Then became a fine

■ —i-ij— TT η j τ __ _j-_ j -__ .. τ _ j __ _ λ j- .j__ ..κα-i ...

V CA KCXXIlC UUX ^ UXJ < XUJ> XUV / C Xtt I / OUU4.UXUU U ·. *. «· UW« OT «« M «^ QW

Dispersion mixed so that the solids content of the. Resin and filler was 40 wt. # Of the dispersion. The calcium carbonate used is under the trade name CAMEL WHITE from Harry T. Campbell Sons Co., Towson, Maryland. The VINAC 880 emulsion was used as the polyvinyl acetate emulsion Air Products and Chemical Company in Allentown, tk.

The paper sheets were immersed in the dispersion and then squeezed between two rubber rollers, at which the excess dispersion is squeezed off the leaves. The impregnated sheets were then dried for four minutes at 100 ° C., each Side 2 minutes each in a Williams paper dryer. These sheets were then kept for several days, before they were tested. The tear, fill and fold tests were then carried out according to the TAPPI standard

7230/01 / Ch / Fr

- 18 -

September 10, 1976

dard. The results are given in Table I. Oil resistance was determined by typing letters on the paper with a commercially available typewriter and then determining how easily or how difficult the letters could be removed by erasing them with an eraser. Since the ink in conventional typewriter ribbons contains a substantial proportion of non-dry UIe, there is a direct relationship between the loadability of the paper and the oil-repellent properties. The designation "excellent ¹¹ " means that the letter was completely removed with just a few erased strokes. The term "good" means that after a few erased strokes the letter was still easily visible, but not in

OTWXVtO. UXC

moderate "means that the etching was still acceptable. The term "bad" means an unsatisfactory etching.

The solvent resistance properties were determined by placing a purple drop _; \ of toluene on the surface of each leaf, left in contact with a specific area of that surface for thirty seconds. The toluene drop was then wiped off with a paper towel, but the area was wiped once with a paper towel which was very dense with undyed toluene. In this way it was ensured that the paint on the surface was completely removed, so that the degree of penetration of the paint into the paper could be determined. The term "good" means that the penetration took place at various points, but the degree of discoloration was slight and

7230/01 / Ch / Fr - 19-10 September 1976

in each case was less than 50 % . The term "fair" means that there was little discoloration over most of the test area. The term "bad" means that the entire test area turned dark. The term "very bad" means that the ink penetrated the paper all the way to the back.

The results of the tests are given in Table I. The designation XD means that the test was carried out across the machine direction Paper. The units of measure and the identity numbers of the standard attempts of the various examples are in Table I given.

- 20 -

Table I Filler content and physical properties

CaCo, / polyvinyl acetate

Sample ratio of tensile strength CaCo ₃ / PYAC speed (XD)

0/100
10/90
20/80
30/70
40/60
60/40
70/30

80

91

112

105

117

95

96

147

Folding Mullen

31Ή 3610

6013 5535 4455 3429 111

Oil resistance solvent resistance

78 very good very good 75 very good very good 75 very good very good 75 very good very good 74 Well very good 71 Well Well 64 mediocre mediocre very bad very bad

* 'Paper before treatment

1 TAPPI Standard Test No. T4i4ts-64, units in grams

2 TAPPI Standard Test No. T423os-50, number of folds to failure

3 TAPPI Standard Test No. T-403, units in pounds per square inch

7230/01 / Ch / Fr - 21-10 September 1976

- 22 -

From the table above it can be seen that the untreated paper (Sample H) had a tensile strength of 147 grams. A corresponding sheet impregnated with its 100% solution of polyvinyl acetate (Example A), on the other hand, had a tensile strength of 80 grams . However, if the impregnation compound is mixed with calcium carbonate in an order of magnitude between 10 to 70 % , as shown in samples B to G, then the tensile strength is probably reduced, but not to the same extent as is the case with impregnation with 100 Ji polyvinyl acetate Case is. The oil resistance and the resistance to solvents were retained even if the impregnation compound contained up to 70% by weight of calcium carbonate. It should also be noted that the folding fatigue strength was greater when using an impregnating agent provided with fillers than when the impregnating agent consisted of 100 Ji of polyvinyl acetate.

Example II

The test procedures described in relation to Example I were repeated. Instead of calcium carbonate, however, this time kaolin clay was used as a filler. This is a sound which sold under the tradename HYDRAPRINT by J. M. Huber Corporation of Huber, Georgia will. The results are given in Table II. '

sample

Table IT

Filler content and physical properties clay / poly winvlacetat

Clay / PVAC ratio

Zeridfestig- folding oil resistance speed (XD)

A. 0/100 80 B. 2C / 80 117 C. 30/70 114 _D. '«Ό / 60 117

3171

4179

very good very good very good good

Solvent-? <■ resistance - · '- ■

very good very good very good very good

7230/01 / Ch / Fr - 23-10 September 1976

The tests listed in Table II indicate that the Results with kaolin clay and with calcium carbonate essentially were the same, d. H. the paper exhibited roughly the same properties in each case.

Example III

To illustrate the importance of impregnating the paper with a polymer with a certain hardness, the paper according to Example I was impregnated with a series of polymer-filler mixtures, the polymers differing only in terms of the film-forming temperature (Tg). As already mentioned at the beginning, the Tg is a measure of the hardness or rigidity or film rigidity of the polymeric material. In the example, the polymer was mixed with calcium carbonate in a ratio of 60 % polymer and 40 % calcium carbonate. The results are given in Table III.

7629460 03/24/77

Ib

Table III

Elasticity of the polymer measured by the film-forming temperature and the physical properties - vinyl acetate and polyacrylates

40 % CaCO ₃ /60 % polymer

Commercial impregnation final sealant activity polymers

(kg / mm)

Tg ( ⁰ C) Zerreißfe- Bruehfe- Faltfe- oil resistance resistance

(g) (XD)

(psi) (Mullen)

frsELvacrvlate

§Joplex B-85 26.3 193.1 101 + 101 gioplex AC 201 32.7 232.4 29 ° 94 ghoplex TR407 28.3 223.5 22 ° 89 ^ ioplex B 15 26.3 225.3 O ⁰ C 97 Rhoplex E 49 29, ί 236.0 <0 ° C 113 Polyvinyl acetates

Resyn 1105 27.7 Vinac 880 38.2 Resyn 1255 29.1 Resyn 5000 31.7 Resyn 2873 24.6; * uncalendered

223.5 220.0

44 ° C 31 ⁰ C

23 73 79 57

61

72 74

Number (XD)

27 1761 4093 3589 1752

1927 5b85

Solvent resistance

very bad very good very good bad very bad

good Good

very bad

Well

Well

bad

bad

Good Excellent

214, 5 16 ⁰ C 109 67 1371 mediocre mediocre _# J j 220, 0 2.0 ⁰ C 114 70 2744 bad mediocre ^"": 227, 0 -36 ⁰ C 122 45 189 Bs2hr bad poorly% ^·:

7230/01 / Ch / Fr - 25-1C. September 1976

From the above data it can be seen that a ^{paper impregnated with polyvinyl acetate with a Tg of 16 °} C. had a mediocre resistance to oil and solvents. If, on the other hand, the paper was impregnated with a polyacrylate with a Tg of 101 ^° C., then the paper showed no resistance to oil and solvents. It follows from this that a favorable polymer material should preferably not have a film forming temperature in the range of about 15 ° to about 100 °, than 60 ⁰ C. In this connection, reference is made to the Table VIII with respect to a polyvinyl chloride having a Tg of 60 ⁰ C. The preferred Tg range should be between 22 ⁰ C and 44 ° C, so as to ensure that the polymer with the usual in paper machines temperatures melts.

Example IV

The types of mineral fillers that were used as an extender for the impregnation compound contribute significantly to the properties of the impregnated paper. In the present example, a starting paper according to Example I was used, which was impregnated with polyvinyl acetate, which was mixed with a number of different mineral fillers. Each mixture consisted of 40 % fillers and 60 % polyvinyl acetate, each based on the dry weight. The calcium carbonate and clay were the same as in the previous examples. The talc used is available under the trade name MISTRON VAPOR from United Sierra Division, Cypress Mines, Trenton, New Jersey. The mica is like him

- 26 -

7230/01 / Ch / Fr

- 26 -

September 10, 1976

under the trade name DAVENITE MICA P-12 from the Hayden Mica Co. of Wilmington, Massachusetts. The diatomaceous earth is available under the trade name CELLITE from the Johns-Manville Corporation, New York, New York available. Any of the aforementioned Fillers were used of the commercial grade used in papermaking, with particle sizes ranging between 2 to 5 microns. The results are in Table IV reproduced.

- 27 -

■■ -. s-

J.

used filler

Impregnation compound (%)

Table 3 .V Various fillers

60 % Polwinvlacett .t AO % filler

Dense- Zerreiß- Faltfe- Bruchfe- Oil resistance impr. strength strength stigk. was standing in kg / mm (g) (XD) number (XD) (psi)

(Mullen)

Solvent resistance

31.7 245.0 80 3171 78 very good very good f - finer, 117 5585 74 Well very good ■ \
ro • Ä ^a ° ³ 117 4179 * Well very good I. Γ \. ^: j 34.3 220.0 101 3334 84 Well mediocre ! DAVENITE • Mica P-12 32.4 216.3 99 2825 81 Well very good ■ · CELLITE • · · ι
····,
• ΐ Diatoms ··· * Earth 32.4 207.4 100 2234 84 bad bad · ■ «·
• * · * 30 % clay * · Uncalendered

7230/01 / Ch / Fr

- 28 -

September 10, 1976

From the table above, the results with calcium carbonate, clay, talc and mica are satisfactory while diatomaceous earth is unsatisfactory because of its poor resistance to the penetration of oil and solvents.

Example V

The effect of using paper with different densities in the non-impregnated state is shown in the present example. An aqueous dispersion of polyvinyl acetate and calcium carbonate was prepared according to Example I. The polymer-filler mixture made up 40% by weight of the dispersion and the ratio of polymer to filler was 60:40, based on weight. A number of sheets of unsized paper with different densities were immersed in the dispersion and the excess portion of the impregnation compound was removed by passing the sheets through gunsmith rollers. The surface of the leaves was then cleaned with a paper towel to ensure that the impregnation compound was completely removed from the surface of the leaves. The leaves were then dried for four minutes at 100 ^° C., conditioned for several days and, as already mentioned, tested. For comparison purposes, a dispersion was prepared which contained only 40% by weight of polyvinyl acetate. A second set of the starting paper was then impregnated in the manner previously described. For comparison purposes, a non-impregnated paper was ultimately tested. The results are given in Table V.

Table V

not impregnated

paper

Starting weight
(kg)

Tightness kg / mm *

sized paper impregnated paper with 10096 P VAC 7-Pt

Sheets impregnated with 4096 CaCo / 6096 PVAC

Zer- ΟΐΞ Fait- Zer ~ FaIt- Zerrei Fait- Olwi-Impräg-PVAC / tear-resistant- tear-resistant, firm, derniermas-CaCo, * strength f) strength (XD) (f) stand se (90 kg / πώ speed Tg) ** (XD) (g) (f)

(XD) (XD)

is

rs »F

13.8

14.4

15.6

19.2

17.2

23.3

15.6

15.6

15.1

17.4

98.3 123.3 130.5 150.2 162.7 168.0 175.2 184.2 196.7 230.6

45.8 48 _V 5 47.7 33.5 29.3 38.2 36.2 26.9 25.5 9.1

9.7 11.3 12.3 11.0 11.1 12.1 12.3 12.4 14.1 14.2

52 65 94 66 50 117 50 56 52 30

N P E F E G E E G E

594 2774 3200 3221 2687 5585 3221 1351

704 3621

32 74

78

118

147

64

61

50

25th

10 11

153 93 199 2247

38 67

60 46 80 46 53 56 34

821

2207

2291

3171

2207

958

350

N P G F E E E E G E

*
♦ *

uncalendered

N-none P = bad E = very good F = average G = good

IT- Λ

The table above shows that the density of the non-calendered starting paper should be greater than 123 kg / ran according to sample B. The maximum density of the non-impregnated and non-calendered paper should not be higher than 200 kg / mm according to sample I. Although the sample according to B had 48.5 % impregnation compound, it was not satisfactory with regard to the oil resistance. Although Sample J had excellent oil resistance properties and contained 9.1% impregnation compound, the tear strength was relatively poor. It is further to be noted that each of the papers which can be described as satisfactory had a final density before calendering of more than 187 kg / mm and less than 250 kg / mm.

7230/01 / Ch / Pr '' "-30- ΊΟ September 1976

Example VT

The amount of polymer filler impregnant which is desirable to obtain the desired properties is shown in the following example, where a starting paper was used which was made from a bleached Northern pulp containing 5 % titanium dioxide. Although the paper was not sized, it had a slight glue effect. However, this slight glue effect was by no means so strong as to prevent the impregnation compound from penetrating into the interior of the paper . The initial weight of the paper was 15.57 kg (based on 500 sheets of size 610 χ 914 mm). The samples were produced as described in Example V, but the proportion of solids in the impregnation compound varied between 10 % and 40 %. The results are given in Table VI. .

"m9hmmm.fr

Table VI

Resin content and physical properties 60 % PVAC / 40 % CaCO ₃

Polymer tightness folds tearing · " Sample filled with impregnation (number) proportion (kg / mm) *:

A.
B.
C.
D.
E.
F.

0 96
6.0 96

11.1 96
15.6 96
24.0 96
20.6 96

30.2 96

1 - source paper

2 - 100 % PVAC

* uncalendered

184.2 184.2 191.3 196.7 223.5 220.0 232.4

65 1141 1874 3069 2915 1731 831

tear "
tigk.
Gram oil repellent
stable
ability Solid
proportion of impregnation
mass (in %) 58 none 53 mediocre 10 51 Well 15th 56 very good 20th 51 total 30th 56 total 40 53 total

Vi .5 ivi. . · Ί ·,

• · at · · ·· ■

ten in -ν »et · · <·

7230/01 / Ch / Fr - 32 - September 10, 1976

From these data it can be seen that significant oil resistance and wrinkle resistance occurs when the polymer-filler impregnation rate is between 6-10% or around 8.5 % of the weight of the sheet (Sample B), with best results being obtained at one Impregnation mass proportion in the range between 15 to 25% by weight of the sheet, as can be seen from samples D and E.

Example VII

To illustrate the different types of a hard polymer which the present invention can be used satisfactorily in the production of paper according to, output papers were prepared according to Example I impregnated with a polymer-filler dispersion having a solids content of 40 wt.% At a weight ratio between polymer and filler from 60 % to 40 %. The filler was calcium carbonate and the polymers used were RHOPLEX AC-201, a polyacrylic emulsion made by Rohm & Haas Co., Philadelphia, Pa. And GEOW 351, a polyvinyl chloride emulsion made by BF Goodricht Chemical Co., Akron, Ohio. The results are given in Table VII.

- 33 -

7629460 3/24, 77

Table V II

Impregnation compound

Different types, of polymers Impregnation compound stretched with 60/40 polymer / CaCO, and unstretched impregnation compound

Filmbil- Impräg- Dense- Tear- Fold- Fraction- Oilwi- Solution-Polymer dungstemnier- ity impr. firm stigk. firm the- medium-

temperature Tg part (%) (ki; / nom) * (g) (XD) (number) (psi) resistance resistance

(Mullen) **

INJRHOPLEX

is »only Jf RHOPLEX

/ gg Ac / 201

■> «§ ■ ;. λ * * * GEON ¹ 351 / CaCO,

only _o GEON ² 351

Polyacrylate

Polyacrylate

Polyvinyl chloride

Polyvinyl chloride

29

32.7 23i !, 4th

73

20 ° 60 °

60 °

42.0 250.3 42.0 24; ί.

43.2 230.6

1 - stretched impregnating agent 60/40 polymer / CaCO

2 - Impregnation agent not stretched * not calendered

** E e excellent G = good

P «'bad F ■ mediocre

80

7230/01 / Ch / Fr - 34 - September 10, 1976

These data show that an impregnation compound, consisting of a hard polyacrylate mixed with calcium carbonate gives essentially the same effect as a hard polyvinyl acetate mixed with calcium carbonate (compare Tables I and VII). Be it notes that similar results are achieved with an impregnation compound consisting of a mixture of Polyvinyl chloride with calcium carbonate. However, the solvent and UV resistance of the impregnated paper is higher with a stretched impregnant than with a non-stretched impregnation material. From this it is found that beneficial results are achieved when certain types of hard polymer, such as Polyvinyl acetate, polyacrylate and polyvinyl chloride can be used =

Example VIII

The paper according to the present invention has a good abrasion resistance, even if the impregnating agent contains a significant amount of a filler is provided and even if the impregnation mass fraction is considerably less than half the weight of the paper. The abrasion resistance of the paper according to the present invention was determined using a starting paper according to Example I, which was made with various hard polymers and polymer-filler mixtures impregnated in accordance with Example I. The polyvinyl acetate was VINAC 880, the polyacrylate RHOPLEX 407 and the polyvinyl chloride GEON 351. The sheets were a Tabor ab-

.-7kc .;

7230/01 / Ch / Fr

- 35 -

September 10, 1976

ir

Rub test according to the TAPPI standard (TAPPI T 476 ts-63). An H-18 abrasive wheel was used in this test was used, counting the number of revolutions of the wheel until there was a hole in the sheet of paper. The results are given in Table VIII.

- 36 -

7629460 2 iIi 77

after Table VIII Rads mii • Impregnating agent content (%) , 7
, 2 Tabor using a 31
32
32 Abrasion test H-18 roughness {υ only polyvinyl acetate
CSP polyvinyl acetate / 30 % CaCO
■; ro Polyvinyl acetate / 30 % clay Revolutions to the point of blessing _j impregnating agent 600
₃ 530
800

only polyacrylic polyacrylic / 40 % CaCO ₃ only polyvinyl chloride polyvinyl chloride / 40% CaCO ₃

untreated original paper

1500 1700

354

400

20-50

39.5 28.3 43.2 42.0 O

7230/01 / Ch / Fr - 37 - September 10, 1976

From the available data, it can be seen that the abrasion resistance of a paper sheet coated with a polyvinyl acetate and a mineral filler, such as calcium carbonate impregnated, is only slightly less (530 revolutions) than with one Paper that has only been impregnated with polyvinyl acetate (600 revolutions). Paper made with polyvinyl acetate, mixed with clay, impregnated has a greater abrasion resistance than a paper which has only been impregnated with polyvinyl acetate. A higher abrasion resistance also shows with polyacrylate and calcium carbonate impregnated paper on in comparison to a paper that without filler with Polyacrylate has been impregnated. The abrasion resistance of one impregnated with filler and polyvinyl chloride Paper was slightly higher (400 revolutions) than a sheet of paper that was impregnated only with polyvinyl chloride has been.

Example IX

A paper according to the present invention must with the previously described dispersion are impregnated. Coating with the dispersion is not sufficient. Around To show this, a paper with an initial weight of 24.3 kg (500 sheets of size 610 χ 914 mm) was used. and a thickness of 0.139 mm impregnated and coated with a polymer-filler mixture. For example, was a starting paper impregnated with a mixture described in Example I and another paper was with coated with the same mixture as that in U.S. Patent

- 38 -

7230/01 / Ch / Fr - 3Ö - September 10, 1976,

3,634,298, with the exception that the polymer named in Example I of the patent was replaced by VINAC 830 _; Polyvinyl acetate mit.einer film forming temperature of 31 ⁰ C. This polyvinyl acetate was used for preparing the aqueous clay-polymer dispersion. The dispersion had a solids content of 55% by weight, the clay / polymer mixture being present in a ratio of 93 % clay and 17 % polymer. The resulting dispersion was coated onto one side of the starting paper as a layer using a Meyer doctor blade according to Example I of the patent. The paper coated in this way was dried at 150 ° C. for one minute. Both the coated and the impregnated paper were then tested for tear strength, breaking strength and folding resistance, the results of which are shown in Table IX.

sample

CO output J? · paper

Impregnated base paper

Vinac paper pigment density (mm)

Table IX

Folds

Tight- Tear- Mullen 10-20 96 90 Ji Splitting-

strength (psi) relative relative resistance

(kg / mm) (g) Moist- Moist- (gm / in.)

speed

0.14 175.2 115 32.8

30.3 0.138 255.6 89 76.4 1284 1633

7018

200

800

Base paper coated 24.7

0.16 203.8 136 48.0 1065

200

7230 / of / Ch / Fr; -40- September 10, 1976

The table above shows that the tensile strength decreases by about 13 % with an impregnation, while it increases by about 12% with a coating. The impregnation doubles the breaking strength, while with a coating only an increase of about 50 % is noticeable. The impregnated paper has a folding durability which has increased by more than double »even at a relative humidity between 10 to 20%, while with the coated paper this folding durability decreased by about 3096. The nip resistance of the coated paper was the same as that of the base paper, but the impregnated paper was found to have a nip resistance of more than 600 g / ⁿ , ie a value at which the paper tears instead of splitting. From the above it follows that the polymer-filler mixture must be impregnated into the paper web and it is not sufficient to merely coat the surface.

The above-mentioned folding strength is also referred to as folding resistance. The breaking strength can also can be referred to as burst resistance and the tensile strength as tear resistance.

The density information in kg / mm for 500 sheets of size 609 »6 x 914.4 mm was derived from the density information in lbs / mil for 500 24 "χ 36" sheets. Should the Density are given in g / cm, then the above kg / mm data are to be divided by the factor 278.7.

- 40a -

• φ φ φ φ 9 · Φ · · · ·

7230/01 / Ch / Fr - 40a - September 10, 1976

A paper with 125 to 200 kg / mm (corresponding to 7 to 11 lbs / mil) based on 500 sheets of size 610 χ 915 mm accordingly has a density of 0.4485 to 0.7176 g / cm.This one with 187.7 to 250 kg / mm (corresponding to 10.5 to 14 lbs / mil) on the same basis has a density from 0.6735 to 0.8970 g / cm.

If the weight per unit area is to be converted to g / m 2, then the kg / mm information must be divided by the factor 10.96. A paper with 125 to 200 kg / mm on the aforementioned basis or one with 187 »7 to 250 kg / mm on the aforementioned basis has a basis weight of 11.40 to 18.25 g / m ² or 17.13 up to 22.81 g / m ² .

- 41 claims

Claims (1)

Expectations / 1 * Refined paper made from cellulose fibers with an in ^ Paper dispersed impregnating agent, characterized in that the paper consists of about 8.5 up to about 50 wt. 96 impregnating agent, based on the final weight of the paper, whereby the impregnating agent * tel consists essentially of about 35 to about 90 wt. 96 of a hard polymer and of about 10 to about 65 wt. 96 of one inorganic filler, based in each case on the weight of the impregnating agent. 2. Paper according to claim 1, characterized in that it has about 8.5 to about 50 wt.96 impregnating agent, based on the final weight of the paper and this impregnating agent consists essentially of about 35 to about 90 wt. 96 of a hard polymer and from about 10 to about 65 wt. 96 of an inorganic filler, based in each case on the weight of the impregnating agent, whose constituents give the paper a good Resistance to tearing, wrinkling, abrasion and the penetration of Ul and solvents give. 3. Paper according to claim 1 or 2, characterized in that the dry tightness of the non-> calendered, unimpregnated paper between facing surfaces is between about 125 to about 200 kg / mm (7 to 11 lbs / mil). - 1 * 2 - "! * J J 7230/01 / Ch / Fr - 42 - September 10, 1976 4. Paper according to claim 1 or 2, characterized in that the polymer has a film formation temperature in the range between about 15 ° C and about 60 ° C. 5. Paper · according to claim 4, characterized in that the film forming temperature in the range between about 22 ⁰ C to about 44 ° C. 6. Paper according to one of claims 1 to 5, characterized in that the tightness of the uncalendered paper at least about 187.7 kg / mm (10.5 lbs / mi.1) and no more than about 250 kg / mm (14 lbs / mil), based on 5Ou sheet of size 609.6 χ 914.4 min, amounts to. 7. Paper according to any one of claims 1 to 6, characterized in that the Imprägniermittelanteil is located on the final weight of the paper in the range between about 15 to about 40 wt.%. 8. Paper according to one of claims 1 to 7 _f, characterized in that the proportion by weight of the filler in the impregnating agent is between about 20 % and about 65 % . 9. Paper according to one of claims 1 to 8, characterized in that the polymer consists of at least one of the following polymers or mixtures thereof: polyvinyl acetate, polyacrylate and polyvinyl chloride. - 43 - te i \ ', Ii Λ.>. ^15th 1 5 It · »» It »»> »1» · Ii > t · · «II» · IiII · 7230/01 / Ch / Fr - 43 - September 10, 1976 10. Paper according to claim 9 »characterized in that the polymer is a copolymer
and / or homopolymer. 11. Paper according to one of claims 1 to 10, characterized in that at least ei., "* He the following fillers or mixtures thereof is present in the impregnation agent: clay, calcium carbonate, Mica and talc. 7829486 2 ta 77