DE2340740B2 - METHOD FOR MANUFACTURING PLASTIC-IMPREGNATED CORRUGATED CARDBOARD - Google Patents

Description

The invention relates to a method for the only feasible procedure because one "Division of Weilpappen with excellent water- 4 ° the condition was that the treatment liquid strength and high mechanical strength in one the individual boards, if they are in large numbers wide temperature range. were subjected to the impregnation at the same time,

For the packaging of water-containing goods, there is hardly any between the individual cardboard boxes Turned corrugated cardboard impregnated with wax until there was a gap, butt firmly together the disadvantage that it would stick in high environments *: - 45.

Temperatures lose their strength and therefore as with corrugated cardboard, which are cut so that they

At high summer temperatures, packaging material cannot be deformed directly by folding into cardboard boxes. This disadvantage is related to the ability, and which are so summarized in large numbers for the treatment of the low melting point of the wax, also consists in the simple fact that with increasing temperature, the strength of the cardboard 50 drying after impregnation tends to decrease and decrease a temperature of forming a resin film on parts, which is immediately to 6O ⁰ C or above unsustainable. be in contact with the outside air before the

On the other hand, this treatment liquid impregnated with wax gets into the interior of the cardboard Corrugated cardboard is hard and can penetrate at low temperatures, so that the impregnation is uneven. At low host temperatures, 55 is moderate.

therefore in these paperboards, when they are bent or folded, the object of the invention is to create a fold easily cracks, and this tendency to crack, in which a deep, rapid and even education increases with falling temperature. Penetration of the impregnation agent into the individual

Corrugated cardboard, which is guaranteed instead of waxing with artificial cardboard of a whole bundle and that Are impregnated with resins are also known, but solvents are as complete and safe as possible cardboard of this type has not been recovered for a long time.

can maintain their strength. In addition, the subject matter of the invention is that in claim 1

the process for their production various after-marked processes.
share in. The im-

If a synthetic resin is used for the impregnation, 65 impregnated corrugated cardboard blanks (hereinafter referred to as usually requires a solvent; often called cardboard), are available over a wide range of times Losses and impurities easily occur in the temperature range unchanged and have a high level Ambient atmosphere and risk of ignition on, water resistance on.

In the following, the invention is incorporated into the interior of the paperboard by means of resin

Drawings explained in more detail, in which, a viscosity of the treatment liquid of

F i g. 1 shows a flow sheet with essentially 1-2000 cps not to the difficult directions described above and arrangements for carrying out a task, but rather for good results. It is with that special implementation form ücs according to the invention 5 method according to the invention are therefore not required Method and paid great attention to the adjustment of the viscosity.

F i g. 2 dedicate a similar flow chart for explanation. While the aforementioned

Another implementation of the invention difficulties also in the case of impregnation with

mean according to the procedure. Wax occur, the inventive method

In the in F i g. 1 device shown is an io drive not affected by variations in viscosity.

Impregnation and drying vessel 1 shown, impregnates, but always leads to a good product

that has a capacity to process a quality. In this context, it should be added

Batch of about 100 cardboard is sufficient. It is not wise for every resin depending on its

required between each cardboard gaps molecular weight and its nature an optimal

so that the paperboard is in intimate contact with viscosity.

stand each other. Even under these conditions, the strength of the paperboard obtained increases with the

adjacent cardboards do not adhere to each other, and there is a concentration of resin in the treatment liquid,

even impregnation can be achieved. and the outside of the cardboard turns black or dark.

To the extent that the air from the impregnation When the resin concentration is 20% or less

and drying vessel 1 is 20 using the vacuum pump 2, an intense dark color does not occur,

is removed, the treatment liquid is removed and the aesthetically pleasing exterior of the cardboard

a tank 3 is supplied to the container 1. is preserved.

The individual cardboards are not laid horizontally.

placed one on top of the other, but in a vertical arrangement approximately and drying vessel 1 located cardboard

arranged side by side to form a block. 25 is 5 to 10 minutes. Then the

In this way, the cardboard is returned to the tank 3 with air impregnation liquid.

spaces arranged through the corrugated, and at the same time are inert gases, such as

Intermediate layers run in the vertical direction where nitrogen or carbon dioxide is introduced into vessel 1

by quickly removing the impregnation line. This procedural stage of the replacement of the

liquid is guaranteed by allowing it to drain. 30 solvent with inert gases is only in the cases

In addition, these air gaps are required in which a flammable solvent,

Drying air at high temperature through - such as toluene, is used, but not when a

flowed, whereby the paperboard is used on effective non-flammable solvents, such as

Way can be dried. Trichlorethylene, the replacement of the solvent

Examples of usable resins in the hand- 35 simply carried out by atmospheric air

treatment liquid are polystyrene resins, chlorinated poly- can be.

propylene, petroleum resins, vinyl chloride polymers, the next process step is pre-drying, Vinyl acetate polymers, maleic acid resins as well as those which take place because of this, in order to avoid uneven interpolymers from it. Poly-impregnation is to be prevented from these. In many cases where styrene resins are particularly suitable. Reasons for the 40 the cardboards in such a way in the vessel 1 for impregnation Suitability of these resins are their high strength and drying that they are introduced immediately according to their high molecular weight and should come into contact with the outside air, such as relatively low prime costs. for example in the case of paperboards made in this way

Examples of solvents which are shaped in the treatment so that they become superfluous after folding in cardboard boxes can be used, are to be seduced, 45 penetration of the resin takes place various aromatic and aliphatic orga- in this part in the paper layers do not take place, niche solvents, such as toluene, but a film forms on the surface, Xylene, methanol, acetone, η-hexane, trichlorethylene which causes the irregular impregnation mentioned and carbon tetrachloride. These solvents have come about. It is imagined all of them inexpensive, and of them toluene 50 spaces are in the slotted part that is perpendicular and xylene are particularly suitable. is arranged to the folded (corrugated) part,

It has been found that the composition of which in turn is arranged horizontally, on one Treatment liquid preferably through 5 to appropriate place on each cardboard. In these inter-20 Parts by weight of resin and 80 to 95 parts by weight of space air enters, and when drying from the upper solvent is marked. The viscosity of the 55 surface of this part willow a blackening as well Liquid varies with the composition and creates a sheen. Therefore, to prevent a increases with the resin concentration. such discoloration an appropriate treatment

When the cardboards are impregnated piece by piece. A circular flow or a

be, the impregnation liquid are a closed flow circuit through the impregnation

If the viscosity is over 100 cps, there is a tendency to use 60 impregnation and drying vessel 1, a heating

that the degree of impregnation at different points device 4, a circulation fan S and a front of each Cardboard is different or that the resin is in the direction 6 for the recovery of the solvent,

Cardboard in the form of lumps or foam sticks. which are arranged in the order given, It was therefore necessary to model the viscosity in this way. First, the heating device 4

regulate it to be below 100 cps. 65 and the circulation fan 5 set in motion to by

In contrast to this, in the circuit according to the invention, gas of high temperature leads to process, in which a considerable number of pumps, and the cardboard present in the vessel 1 Cardboard is impregnated at the same time and then it is pre-dried in this way for about 5 minutes.

Due to this pre-drying, the inside is loaded, along the track in the entrance

the cardboard gaps formed, which drove the preparation and preparation chamber 9, where there:

make the final impregnation step easier. There first gate 13 is opened and closed to the

it has been found that during the pre-drying, car 8 must be allowed to pass through. Under this one

preferably a gas flow rate in the 5 occurs and preparation chamber 9 is a Behänd

Order of 100 to 200 m ³ / min and a lungsbadtank 14 arranged with the Behänd

Temperature of about 120 ⁰ C can be maintained. treatment liquid from a reservoir 15 ver

After that, the solvent or the solution is taken care of. In the cases where that used

Medium vapor from a solvent tank 7 into the solvent is flammable, the air is inside the dei

Impregnation and drying vessel 1, and io chamber with the help of a vacuum pump or a «

a circulated gas of high temperature, vent 16 removed and replaced by an inert gas, such as

which is made up of solvent vapor and inert gases (or, for example, nitrogen or carbon dioxide).

The cardboards are put into the impregnation bath tank

saturated steam. The obtained is immersed with solvent 14 and after about 5 to 10 minutes this

steam saturated gas is withdrawn about 5 minutes through 15 bath.

sent the circuit, whereupon the solution. Then the downstream door 13

Medium steam on the surfaces of the cardboard condensate open and the carriage 8 in the subsequent

sated. The resin film that extends through the preceding chamber 10 to saturation with solvent vapors

Impregnation on the surfaces of all cardboard. Although not shown in the drawing

has formed, is by the solvent, which is 20, this chamber 10 is with a circuit, loading

In this way, while the film is rotating, it consists of a circulation fan and a heating element.

condensed, made to progress in the direction endowed, by the gas of high

To penetrate the inside of the cardboard. In this way temperature is circulated to the cardboards

the resin film is dissolved, and the dissolved resin penetrates to pre-dry. After about five minutes of this

evenly in the entire interior of the cardboard in a 25 process step, the gas is of high temperature

and improves their strength. temperature with the solvent or its vapor

After that, the flow of the solvent or saturates, and that way with the solvent

interrupted by its vapor in the vessel 1 and saturated gas of high temperature is bypassed

the solvent recovery unit 6 circulates. The solvent vapor then condenses

Running set in operation to air of high tempe- 30 on the cardboard at low temperature and dissolves the

let the temperature circulate for 25 to 30 minutes. On resin film on the surfaces of the cardboard so that the

This way, the main drying step is through- resin can penetrate the voids that are inside

out and at the same time the solvent through the cardboard through the described pre-drying

Recovery unit 6 recovered. step have been formed.

The solution recovered in this way was placed in the desiccant is from the device 6 in the solution chamber 11, in which a circuit from a heating medium tank 7 passed, from which it is in the treatment direction 17, a circulation fan 18 and a liquid tank 3 or the impregnation and solvent recovery unit 19 is formed, Drying vessel 1 is passed. is the gas mixture of solvent vapor and

According to the method described, which heats the 40 inert gas (or air) to about 12O ⁰ C and 25 to

Drying and recovery of the solvent circulated for 30 minutes to dry the cardboards,

including treated cardboard, the solvent is recovered at the same time.

Vessel 1 removed as a product. After in order to accomplish that the cardboards in this

Process according to the invention can remain under the drying stage for a relatively long time,

described conditions in one hour about 45, the drying chamber 11 is relatively long

3000 kg of cardboard can be treated. trained so that there are five or six cars in it

The above with reference to FIGS. 1 described can be accommodated at the same time. The back

Implementation of the solvent obtained according to the invention is converted into a solvent

Driving is a discontinuous process, tank 20 is directed and can be used again.

in which, after a treatment cycle has ended, the carriage then enters the outlet chamber 12

a new batch is placed in the treatment vessel 1 and is made from it with the finished cardboard on it

and the procedure described is repeated. rolled out. If necessary, the outlet chamber

The invention is not, however, provided with an abundant amount of an inert gas such as

discontinuous process limited, but may prevent air from entering the drying chamber

also applied to a continuous process 55 11 to prevent.

are, as shown on the basis of the implementation form in this in F i g. 2 procedures are

Relation to F i g. 2 will be described. loading the carts with cardboard to be treated

First, in this embodiment one and one after the other through those described above a predetermined number of cardboard boxes sent in a trolley with 8 chambers, the process being continuously loaded, that runs on a track. Along this 60 borrowed without interrupting the work process through tracks there is an entrance and a demonstration one after the other. Here, 3000 kg or preparation chambers 9, which are also treated as impregnation more on cardboard, Chamber is used, one with solvent vapors. In this way, according to the invention, large saturated chamber 10, a drying chamber 11 treated cardboard quantities simultaneously and together and an exit chamber 12 is arranged. Everyone will be 65 - in contrast to the method in which of these chambers is treated from the neighboring chamber one cardboard after the other -, and separated by a door 13. the treatment can be carried out without

Each car 8, which is made with untreated cardboard between the individual cardboard gaps

5 23 40 740 fe

I 7 8

I would have to stop and maintain. In addition, this procedure increases the strength of the

I the risk of fire and the risk of explosions cardboard produced according to the invention further increases.

I and other incidents when using Further advantages of the method according to the invention

£ Flammable solvents avoidable if they are that the solvent is recovered ; i, as described above, inert gases are used as protective gases 5 and are used again.

j; used. Another advantage of the method according to the invention

% As described above, the paperboard, which is the one that is contrary to known processes

I are arranged vertically in the form of a block, in a treatment liquid of high viscosity

I dried this form after one can be turned over redundant. Accordingly, an economic

I The impregnation agent has drained off. The dry economic utilization of the solvent, a higher one

It is created by blowing hot air through it in the degree of impregnation and increasing the strength

S: Direction of the channels to be achieved in the corrugated material that of the cardboard. Besides, there aren't any

I cardboard, whereupon the special measures flowing through these channels to adjust the viscosity

I hot air requires drying in the direction of the interior of the treatment liquid.

I causes the corrugated cardboard material, and the resin 15 To further explain the advantages of the invention

I does not penetrate the surface of the panel side. In accordance with the procedure, the following are the

I Accordingly, there is no blackening or gloss. Results of strength tests given with

I on the cladding surface, and there is also cardboard that was carried out according to the

i no resin between the lining of a cardboard and find have been treated, as well as with such

I that of the neighboring cardboard, which is why no 20 cardboards that have undergone a treatment with wax

\ Sticking together of adjacent boards were observed. The test results also show that

I is that by the presence of resin between the strength of the wax-treated paperboards

I caused two adjacent cladding sides decreases when the temperature increases or decreases

I would. As a result, the cardboard can after being. In contrast, the strength of the

\ Treatment can easily be separated from each other. 25 cardboard produced according to the invention almost none

I As mentioned above, the formation of a causes dependence on the temperature; with increasing

I films on the outer surface of those parts of cardboard, the temperature increases the strength even somewhat.

which are in direct contact with the outside air. The compressibility in absolute values

are related to irregularities in the treatment. 2O ⁰ C was 116 kg in the case of with polystyrene and

i In this case, most of the resin after 30 has 82 kg in the case of impregnated with paraffin wax

I did not impregnate the inside of the cardboard cardboard.

; reached, but is in the form of the film on In the experiments that the following tables

i the surface. However, the following can be assigned, the resin concentration was 20 Ge

I predrying gaps or voids in percent by weight, the solvent was toluene for poly-

: Formed inside the cardboard. The following petrol, chlorinated polypropylene and vinyl chloride

action condenses the solvent on the upper vinyl acetate copolymer; Acetone for styrene

: surfaces the cardboard and then penetrates further into the maleic resin; η-hexane for petroleum resin as well

I interiors, and the resin, which is the solvent methanol for rosin-modified maleein

accompanied, gets so deep into the interior of the cardboard. acid resin.

Heat resistance test (extent of heart impregnation 20%)

Relationship between temperature and compressive strength

'(100 at 20 ^c C is an arbitrarily chosen initial value for all resins)

20 ° C 40 ° C 60 ° C 80 ° C 100 ° C 120 ⁰ C

\ Polystyrene 100

Vinyl chloride-vinyl acetate copolymer 100 styrene-maleic acid resin 100

Paraffin wax (52 ° C) 100

Wax + resin (7 + 3) 100

Relationship between temperature and burst strength

(100 at 20 ° C is an arbitrarily chosen initial value for all resins)

100 100 108 115 118 100 100 100 101 102 100 100 107 116 119 79 53 - - - 81 61

-20 ° C -10 ° C O ⁰ C 20 ° C 40 ° C 6O ⁰ C 8O ⁰ C 100 ° C 120 ° C Polystyrene 100 100 100 100 100 105 102 100 98 Vinyl chloride vinyl acetate 100 100 100 100 100 102 101 98 98 Copolymer Styrene maleic acid resin 100 100 100 100 100 101 100 100 100 Paraffin wax (52 ° C) 95 95 95 100 90 86 - - - Wax + resin (7 + 3) 95 95 95 100 93 87 - - -

609 521 /

ίο

The results of a water resistance test of the paperboard made with the resin and Solvents according to the invention were impregnated, as well as treated with wax and untreated Cardboard is compiled in the following table.

treatment

Final squeeze immersion in water

dry

after 1 h

Resistance to compression after exposure of rain (amount of rain 3 mm / h) (kg)

dry after 1h 3h 12h

With wax 57.3 11.5 672 645 630 600 According to the Invention 62.4 7.7 465 450 395 357 No 25.6 0 280 0 0 0

In addition, the change in compressive strength and burst strength was dependent on the change the degree of resin impregnation

(Amount of resin incorporated into the paperboard): (paperboard weight) x 100

each determined for samples treated according to the invention and for samples treated with wax. The results are compiled in the following table.

Degree of impregnation and compressive strength

Degree of impregnation 10% 20% 30% 45% 0% 146 189 212 289 Chlorinated polypropylene 100 146 185 210 273 Petroleum resin 100 155 210 260 307 Vinyl chloride-vinyl acetate copolymer 100 153 200 250 310 Polystyrene 100 173 230 278 340 Styrene maleic acid resin 100 165 220 265 315 Modified with rosin 100 Maleic acid resin

Paraffin wax (52 ^C C)

100

250

Degree of impregnation and burst strength

T "ipregnation gra (i For this 10% 20% 30% 45% 0% 140 165 214 241 Chlorinated polypropylene 100 140 160 200 215 Petroleum resin 100 147 173 226 251 Vinyl chloride-vinyl acetate copolymer 100 145 170 220 245 Polystyrene 100 150 180 230 257 Styrene maleic acid resin 100 145 175 228 247 Modified with rosin 100 Maleic acid resin - - - 105 Paraffin wax (52 ⁰ C) 100 1 sheet of drawings

Claims (4)

especially when working continuously. One Patent Claim- Another difficulty arises when the viscosity ment claims. ^ Treatment liquid made of synthetic resin and ιοί. Process for the production of plastic solvent is high, so that the processing of impregnated corrugated cardboard is made difficult. Process ₇ "r indicates that with the solution of US Pat Pb a * -ι» »» ι "" ν s * NREN to or more synthetic resins in organic solu- production of veneer from Kunst.tott known ^ Dalungsmitteln impregnated bundle From corrugated cardboard, paper is pre-dried in a hot gas with a solution of a curable resin in an organic solution, then impregnated with a ca xo with the solvent vapor. The recovery of the solvent is done with saturated hot gas and finally during a single drying step with the same hot gas with simultaneous after impregnation ^ From US-PS 27 89 921 depletion and recovery of the solvent is a process for the treatment of corrugated cardboard middle vapors is completely dried will. by soaking with rosin solution and 2. The method according to claim 1, characterized in that> ₅ closing with a solution of polymethacrylates indicates that the resin used is a polystyrene, an outer coating known to be formed. chlorinated polypropylene, a petroleum resin, a solvent recovery does not take place. Finally, from vinyl chloride, vinyl acetate or styrene maleic the GB-PS 11 33 463 is a process for acid resin or a rosin-modified treatment of paper with the aid of a polystyrene resin and an aroma solution as a solvent known, whereby water resistance and adhesive table or aliphatic organic solubility of the paper or of corrugated cardboard are to be used increased medium. A solvent recovery 3. The method according to claim 1 or 2, thereby also does not take place. Finally from the E) T-AS characterized that resin and solvent in 11 63 774 a method of making one for the Ratio of 5 to 20 parts by weight of resin to 25 laminate production or for surface laminate-80 Up to 95 parts by weight of solvent applied to the usable material by impregnation will. or coating a flat, absorbent carrier, 4. The method according to any one of the preceding such as paper or other fiber claims, characterized in that known as the material with a curable prepolymer of solvent toluene, xylene, methanol, acetone, 30 diallyl phthalates in aqueous dispersion.
η-hexane, trichlorethylene or carbon tetrachloride are used in the known processes for the production of hydrogen. solid corrugated cardboard by treatment with either But above all, the corrugated cardboard or blanks are individually processed one after the other in wax or synthetic resin 35 immersed a treatment liquid and then taken out of her. This practice is an ineffective feature of the Procedure, it was previously believed, however, that it was the