DE1182560B - Process for the production of moisture-proof packaging material from water-sensitive films - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school Class: B 44 d

German KL: 75 c -5/06

Number. 1182560

File number: B 44756 VI b / 75 c

Filing date: May 25, 1957

Opening day: November 26, 1964

The present invention relates to improvements in the production of moisture-proof, film-shaped packaging materials.

It is known to produce moisture-proof film-shaped packaging material by using a consisting of a vinylidene chloride copolymer consisting of a moisture-resistant layer of an aqueous Dispersion of the copolymer on the surface of a solid film made of water-sensitive material applies, e.g. B. a film made of regenerated cellulose, ίο Such a method is e.g. B. in British Patent Specification 663,645. This method is that you have two foils, each with one of their surfaces in the nip between one Bringing a pair of rollers together and an aqueous dispersion of the copolymer constantly in the of the Foil introduces the angle formed immediately before entering the nip and so the surfaces provided with a coating. When exiting the nip, the foils become shorter Time separated from each other when the water from the aqueous dispersion of said copolymer can penetrate into the two surfaces.

Even the smoothing of coatings of various types that are on material webs, for example paper webs, are applied by letting it pass over smooth surfaces, e.g. B. fixed polished Rods and practically dry rollers are known. Methods of this kind are described in the German patent specification 813,361 and U.S. Patents 1,043,021 and 1,955,414. You can do the methods but do not apply when smoothing the dispersions of vinylidene chloride copolymers that are applied to foil. This is because these dispersions coagulate easily, especially when exposed to them of shear forces. A dispersion intended for the production of a coating on foils, which has accumulated on the surface of the smoothing device, coagulate quickly and harden. The smoothing device loses its usefulness considerably as a result of the applied, hardened dispersion, because the resulting bumps on their surface can tear the coating.

The present invention now relates to a method for the production of moisture-proof packaging material from water-sensitive foils, especially Films made of regenerated cellulose, by coating with aqueous dispersions of film-forming Polymers, preferably vinylidene chloride polymers or copolymers, in which each Two webs of the foils pass a nip, the dispersion in the of the foils immediately before Process for the production of moisture-proof packaging material from water-sensitive Foils

Applicant:

British Cellophane Limited,

Bridgwater, Somerset (UK)

Representative:

Dr.-Ing. K. Traetzel, patent attorney,

Wiesbaden-Biebrich, Rheingaustr. 176

Named as inventor:
Cyril Howard Phillips,
Durleigh, Bridgwater, Somerset
(Great Britain)

Claimed priority:

Great Britain May 28, 1956 (16 459)

the entry into the nip formed angle is introduced and the foils when leaving the Roll gap are moved apart again, characterized in that each of the from the roll gap emerging foils with the still moist dispersion coating with the constantly kept water-moist Drum surface of a smoothing roller rotating in the opposite direction to the film erection in contact is brought and then dried.

The film provided with a coating according to the invention is free from unsightly stripes and Lines, even if the coating is carried out at the high speeds that one strives for became.

Water-sensitive films are characterized by the fact that they absorb water when they come into contact with water or water vapor come into contact; included they tend to change their dimensions.

The smoothing roller, which preferably has a diameter between 3V2 and 15 cm, preferably between 5 and 10 cm, can be made of stainless steel or other corrosion-resistant material and is driven at one end by a suitable device allowing rotation in the desired direction.

■ 409 729/336

The smoothing roller can be moistened with water in any suitable manner, e.g. B. by partial immersion of the roller in a water bath or by touching a roller containing water releases to the smoothing roller and in turn is partially immersed in a water bath. The temperature of the water has no meaning and can be between 5 and 50 ° C; Water from the usual temperature of 15 ° C is quite suitable. Excess water that should have come on the smoothing roller can be with Can be removed using a scraper. While the moist smoothing roller rotates the coated one Touches the surface of the film, the layer can be removed to a small extent. A fixed scraper can be used to remove any polymer sticking to the roller fibrous material, e.g. B. felt, be placed under the surface of the water in the immersion bath so that it touches the surface of the roller and washes off adhering polymer.

If the smoothing roller is used in the dry state, the streaks and lines on the Coating layer not completely avoided. In addition, polymer settles on a dry smoothing roller easier than to a water-bearing smoothing roller.

The base to be covered made of water-sensitive material can consist of a web of fibrous Material, e.g. B. paper, exist, or it can be a fiber-free film of organic matter, e.g. B. a regenerated cellulose film made of viscose, cupric ammonia cellulose or any other aqueous solution or dispersion of cellulose has been prepared. Films made from alginic acid derivatives or from protein substance, e.g. B. gelatin or casein, or from low-substituted Cellulose ethers or low-substituted cellulose esters or made from polyvinyl alcohol can also be used will. The film can either be in the form of a continuous web of film or a section of web to have.

Various types of film-forming coating compositions can be used as coating compositions in the process according to the invention synthetic, organic polymers can be used. Polyvinylidene chloride and copolymers

b) 65 to 4 percent by weight of one or more of the following compounds, the one Vinyl group or substituted vinyl group, namely monomeric methacrylonitrile; monomeric alkyl esters of acrylic acid or methacrylic acid with 1 to 5 Kohfenr substance atoms in the alkyl group; monomeric vinyl chloride; monomeric vinyl acetate or monomeric styrene, and optionally

c) 0.5 to 10 percent by weight of an acidic unsaturated compound or a mixture of two or more such acidic unsaturated compounds, namely itaconic acid or itaconic anhydride, citraconic acid or citraconic anhydride, or mesaconic acid; and optionally monomeric acrylonitrile in addition to the vinyl compound or substituted Vinyl compound or mixture of these (b) or instead of one Vinyl compound or substituted vinyl compound if the mixture still has one contains other vinyl compound. The mixture as a whole is 100%.

Copolymers obtained by Polymerization of a mixture containing

a) 35 to 96 percent by weight of monomeric vinylidene chloride,

b) 65 to 4 percent by weight of monomeric acrylonitrile and

c) 0.5 to 10 percent by weight of an acidic unsaturated compound or a mixture from two or more such acidic unsaturated compounds, namely itaconic acid or itaconic anhydride, citraconic acid, or citraconic anhydride, or mesaconic acid. The mixture does not contain any substituted or unsubstituted vinyl compound. The ingredients listed above make up 100%.

Other film-forming synthetic, organic polymers are, for example, polyvinyl

von Vinylidencnlorid'Wrdln'vörzu'g ^ wdse've'men- 45 ^{chloride and} copolymers of vinyl chloride and det. Such copolymers include vinyl acetate. The production of liquid,

aqueous, colloidal dispersions of these polymer

55

for example mentioned:

1. Copolymers obtained by polymerizing a mixture of

a) 35 to 98 weight percent monomeric! Vinylidene chloride and

b) 65 to 2 percent by weight of monomeric acrylonitrile,

namely a mixture that no other polymerizable with monomeric vinylidene chloride Component and not an acidic unsaturated compound, such as itaconic acid or itaconic anhydride, Citraconic acid or citraconic anhydride or mesaconic acid, and in which the ingredients are selected so that they together 100%.

2. Copolymers obtained by polymerizing a mixture of

a) 35 to 96 percent by weight monomeric vinylidene chloride,

sate is known to the person skilled in the art.
In order to make the film impermeable to water vapor, it is not necessary to coat it on both sides, but the two-sided coating is recommended if one wants to prevent the film from rolling.

The aqueous colloidal dispersion of the polymer is applied to the film base in such a düoaea Layer applied so that the water contained in it is completely absorbed by the film base uad the dispersed polymer flows into one another and forms a smooth, transparent coating. That absorbed Water can be removed from the coated film by heating. The coating layer or layers can then be heated as high be that the particles of the deposited polymer from the dispersion combine. The following example is used to carry out the method according to the invention illustrated the device, which is shown schematically in the drawing as an example. The drawing

Claims (1)

5 6 shows the arrangement of a pair of rollers, the water from the aqueous dispersion of the mixed poly- serves, on two sheets of regenerated cellulose each merisats to penetrate the surface of the a thin layer of an aqueous dispersion of the film web 14 is required. This is on the To apply polymer, and of two aqueous dispersion applied with water film web 14 kept moist rotating smoothing rollers, with 5 of them liquid, and the surface of the coating is now Help smooth the smooth, cohesive coating layer through contact with the smoothing roller 17, made of a film-forming synthetic, organic. The scraper 21 made of fibrous material Polymerizate on one surface of each of the two is arranged so that it is below the surface of the the foils is formed. Water 18 in the bath 19 against the surface of the Unless otherwise stated, the parts and i ° roller 17 are pressed and the roller surface from on Percentages in the present description clean any adhering polymer. Parts and percentages by weight. With the help of the deflection roller 22, which is on the uncoated Side of the film web 14 rests, is Example, the coated film web 14 from its web i5 distracted so that it touches the smoothing roller 17. the As can be seen from the drawing, two intensities of contact have little effect on brass rollers 11 and 12, each one of which eliminates the streaks and lines. Therefore, a length of 30 cm and a diameter of 12 cm, even in the case of a film web 14 with good surfaces, is attached in such a way that its axes lie horizontally and essentially tangentially parallel to one another. The distance 13 between the two _ao contact with the roller 17 is sufficient. When the rollers 11 and 12 is set so that it has a wide web of film 14, however, because its edges are about 0.0056 cm. If two webs 14 and 15 are longer than the middle, the contact angle must be made from commercially available "normal" (in contrast to the film web 14 with the roller, enlarged from the further treated, e.g. water vapor impermeable, until the web 14 is over its entire width with a nonchalant) film made of regenerated cellulose, that is to say a 25 of the roller 17 is in contact. Because of this, the water-sensitive, fiber-free, organic sub-position of the deflecting roller 22 can be punched along the sheet JK , each about 0.0022 cm thick and 25.5 cm wide. However, the angle that is made through the gap between the rollers, the deflection of the coated film web from and the rollers 11 and 12 are designated in a different way from their original path, should not be more than driving them at the same speed, in 30-90 °. A second smoothing roller with the one counterclockwise part belonging to it belongs to the film web 15.
the other, rotate. After this treatment, the film webs of colloidal dispersion 45% of a vinylidene chloride 14 and 15 are dried by containing them for 5 seconds of acrylonitrile copolymers (85:15) exposing both foils just before her 35. The gap 13 between the rollers 11 and entry into the roller gap formed angle 12 is then widened to about 0.006 cm See the periphery of the rollers moved (= approximately already coated sides on rollers 11 and 12 0.007 ecm per cm of rotation). With hooves of air, and then, as indicated above, the nozzles (not shown in the drawing), which are applied to the copolymer dispersion. After points about 0.635 cm from which the water has evaporated, the coatings on the edges of the film webs are removed, the two sides of the film webs are hardened by dispersing the films in a small basin or reservoir for 15 seconds of radiation of an electric 16, which is about 24 cm wide and no longer exposed to tric radiators. The layer formed is considered to be about 0.65 cm deep. 45 is about 0.00012 cm thick on both sides of the foil. The route on which the two tracks with their moisture surfaces produced in this way are in contact with the dispersion before impermeable, film-shaped packaging material is they separate, is about 1.25 cm long, and the areas are clear and transparent, with kernel stripes and lines speed at the periphery of the rollers is on and has a permeability value of 120, the 28.5 m per minute. The penetration time of the water 50 according to the "Paper Trade Journal TAPPI Section" from the aqueous dispersion of the copolymer from October 3, 1935 on pages 201 to 209 leg the surface of the two foils was IVaSe, the method written by Charch and Scroggie announce. was determined. After the two film webs have passed the nip, they are separated. Film web 55 14 then runs over the claim with water:
Moist, rotating smoothing roller 17, the coated side of the film web with the roller 17 being in the process of establishing moisture contact. The roller 17, which is driven by means not shown in the drawing made of water-sensitive packaging material, has borrowed foils, especially foils made of regenerated stainless steel and has a cellulose diameter of 7.5 by coating with aqueous diameters cm. It is immersed with its lower part persions of film-forming polymers, in front of the water 18 of the bath 19. preferably vinylidene chloride polymers or The roller 17 is 30 cm from the gap between -mischpolymerisaten, in which two lanes of the removed from the rollers U and 12, i.e. pass a roller gap in 65 foils, the dispersing a distance that is less than the distance traveled by the slides immediately before the the coated web at the angle formed above entry into the nip speed moves during the time it is inserted and the slides when exiting of the nip are moved apart again, characterized in that each of the foils emerging from the nip with the still moist dispersion coating the drum surface, which is kept constantly moist with water, is opposite to the direction of travel of the film set rotating smooth roller brought into contact and then dried. Documents considered: German Patent No. 813 361; U.S. Patent No. 1,043,021,1955,414. 1 sheet of drawings 409 729/336 11.64 O Bundesdruckerei Berlin