DE1403705A1 - Process for the production of laminated bodies - Google Patents

Description

"concerning
Process for the production of laminated bodies.

The invention relates to a method for manufacturing laminated bodies and provides, among other things, a method for laying up bodies made from pure wood or from recycled wood (reconstituted) wood-like panels and for manufacture of laminated bodies connected therefrom in a «continuous process. The procedure is generally based on Board and veneer laminate manufacture is applicable and is particularly useful in making plywood.

Laminate manufacture, particularly the manufacture of plywood, is generally carried out by first applies a damp adhesive to one of the surfaces to be bonded, then another part with one to be bonded Brings the surface into contact with the adhesive and finally apply sufficient pressure to ensure even contact during gluing.

809805/0615

■ UO documents (Art. 7 S1 Ate. 2 No. IS ^ z 3 of the Amendment See3. V. 4. f> 1 « ^r .

1A-21 472

—2—

When performing the. Laminate production is the adhesive on the one surface to be bonded applied by means of a glue application roller. While an applicator roller is used in some cases in other cases, particularly when making plywood, a pair of glue application rollers are used. Will

used on 2 reels, they are usually arranged in this way / that both surfaces of an intermediate sheet (intermediate core) are coated with adhesive at the same time. Of the Roller application of damp glue to a wood surface is not entirely satisfactory.

The application of moist adhesive to only one of the surfaces to be bonded is often disadvantageous. If the surface is very absorbent, the adhesive can penetrate in such a way that a starved bond is created. Such ties are weak. An extra thick adhesive coating compensates to a certain extent for such an absorption; however, this is expensive and difficult to reach _for a high speed during manufacture of layered · plates.

Better bonds are generally obtained if both of the opposing surfaces to be joined have dam adhesive can be coated. While this can be achieved with small adhesions, such as when the

809805/0615

1A-21

-3-

Glue is applied with a brush, so it is difficult to do when making plywood or using other laminated fabrications at high speed using roller application. According to the method according to the invention the advantages of applying the adhesive to both opposing surfaces are equivalent.

Wood veneers are characterized by absorbent spring wood areas, less absorbent ones Summer wood areas and moisture-repellent, pitch-like areas. Peeled veneers are also often holey and bumpy and cracked on the surface. They can also fluctuate so much in thickness that they have fluctuating resistance exercise against the glue application rollers. - ·

The amount of glue that is transferred from the rollers to the wood varies with that of the roller against the pressure exerted on the wood; it fluctuates with the differences in wood thickness and / or the roller spacing (roll spacing) and also varies with the comparable roughness of the wood surface. Strong roller pressure or very smooth wooden surfaces result in a minimal and sometimes insufficient glue application, while low roller pressure or rough surfaces result in maximum and often uneconomical glue application.

809805/0615

1A-21 472

These shortcomings result in very variable order and often unsatisfactory bonds. It is not uncommon for the application on Douglas fir interior sheet material varies from 5 to 10 # on each side of a desired job value. If the order is too small, it will the bond is at risk from drying out, and if the application is too thick, it is a waste of adhesive.

The inventive method provides an exceptional!

wise uniform adhesive film between the ones to be glued!

Surfaces. The amount of glue applied is not affected by the relative roughness or smoothness of the surfaces or by |

change in roller pressure influenced. With this method , the order generally fluctuates less than 1½ on each side from the desired value. j

The present invention is particularly applicable to the automatic or continuous manufacture of plywood, an advantage long sought by the industry.

The new process for the production of laminated bodies

by hot pressing one with an aqueous alkaline

"ι phenol-formaldehyde-containing adhesive solution impregnated j paper web between layers of the connecting materials,? for example, wood veneers, the adhesive preparation having a formaldehyde-phenol molar ratio between 1.5 * 1 and 3 J 1 and evenly applied to the

809805/06 1 5

1Δ-21 472 -5-

absorbent paper web has been applied at a rate of at least ^{1.36 kg resin solids per 92.9 m 2} paper web, according to the invention, that the resinous paper web is placed moist between the - * layers and then hot-pressed without prior significant reduction in the moisture of the adhesive preparation .

The moist adhesive preparation can be applied to the absorbent paper web by roller application, dipping or Can be applied by spraying. The adhesive is preferably applied by roller application on both sides at the same time upset. The moistened web is then between the surfaces to be bonded without letting the adhesive dry or substantially losing the amount of solvent contained therein placed. Bonding is done by applying pressure and heat, depending on the particular adhesive completed the usual plywood making processes.

The exact amount of heat and the pressing time discharges slightly i speaking to the needs of special Klebstoffzube- - fluctuate "ίί reitung If you put a five-layer plywood with a thickness of 9.525 mm (13/16 inoh) forth like that.

Crtf ^ NAL INSPECTED

809805/0615

1A-21 472

-6-

typical conditions for this are holding the press platens at 140.56 ° C (285 ° F) and using a panel pressure of 12.95 kg / cm ² (185 psi) for 7 1/2 to 9 minutes .

The physical properties of the dry paper web s ± ü important. The paper web should preferably be able to absorb the moist adhesive preparation and be evenly impregnated with the adhesive from surface to surface. In the case of webs with low absorption, such impregnation can take place during pressing; so surface application of the adhesive can only take place when the resin is first applied to the web. A preferred material is paper of the type commonly known as "tissue paper" or "toweling paper" or "napkin" paper. The paper can contain wet-strengthening resins, which are desirable because they ensure that the paper is sufficiently strong when wet to be processed and placed on the surfaces to be bonded, * without ■■ · tear. However, the amount of such resins should be so great that they do not significantly reduce the absorption properties of the paper.

Other properties of the troubled paper web are also ~. . $ if important. Its thickness and fiber content should be so: ' Large that it has a maximum adhesive capacity

809805/0615

1A-21 472

-7-

(adhesive holding capacity), agreed with thorough absorption and even distribution of the adhesive, in the web delivers, at least when curing is complete. A web that is too thick or has little absorption and contains too much fiber can only absorb some glue, with most of the glue being concentrated in the near 4-fold paper surface. When pressed, the bond becomes weak, except when the resin punctures and impregnates the web and delamination occurs along the center of the cream between its surfaces. A paper that is too thin will often not have sufficient S-strength to be able to be brought into position on the wood if it is moistened with adhesive.

The adhesive preparation used in the method according to the invention can produce an alkaline condensation product by reacting an aldehyde with a phenol in the presence an alkaline catalyst.

Resin-containing adhesives for common plywood production * g must be made with dry, flour-like substances, such as ground Nutshells, tree bark or superfluous agricultural residues from purfural production mixed will. These substances help to ensure that the adhesive is evenly distributed in the glue application

809805/0615

1A-21 472

-8th-

Resist adhesive penetration into the wood. The properties of the thixotropic viscosity that these substances give the resins impart, also help to apply and reduce drying of the adhesive.

'J Ί

While such additives can be present in the adhesive preparations in the process according to the invention without any harmful effect, their use is not essential. In this sense, the paper carrier serves as a substitute for such additives and ensures a high level of uniformity; Resin distribution on the wood surface. The resin is prevented from unevenly penetrating the wood to the detriment of the final bond, as is the case with non-identical ^;

moderate order. Y / ird such a uniform application of resin; When pressurized and heated, the moist glue flows easily as well as through the web in a required manner . Amount to give a firm bond.

Another important benefit is achieved by using a ·.

wet carrier web as opposed to a dry, adhesive [carrying web. Developed for plywood bonding modern phenolic resins are relatively fast curing as long as they are kept in an aqueous system. Is once the aqueous phase due to excessive loss of water or other solvents from the adhesive from the Bringed equilibrium, the resins can reduce their ability to

809805/0615

1A-21 472 -9- ν

flow and bind well, lose. By apezielle measures such as reduction dea ratio of formaldehyde to phenol resins can be placed, dit receive their · Flieflfähigkeit when dry and Soloh · Hartz can be used to deliver a dry adhesive web to *. However, such dry adhesive taps cure slowly in comparison to a moist adhesive web according to the invention.

In order to ensure rapid hardening of the moist adhesive web, the phenolic resin has a molar ratio of formaldehyde to phenol between 1.5 ι 1 and 3 ι 1 ·

The following examples describe phenolic resins which can be used according to the invention for bonding veneers.

Example I.

A water soluble alkaline phenol formaldehyde resin comes in a resin container with cooling, heating and stirring devices manufactured. The following substances are introduced into the Keseel in the specified quantities:

Material parts by weight

Phenol (90 #) 27.98

Water 5.83

Formaldehyde (37 # unstabilized) 48.88

Sodium Hydroxide Solution (50-6) 5.77

809805/0615

U-21 472

The Gemiach is continuously stirred and converted to 90 ° C in 60 minutes. The temperature is held at 90 ° 0 until a sample showed a viscosity of 65 cSt when measured at 25 ° 0. Ss is then started iU cooling in order to reduce the temperature to 80 ⁰ C! the viscosity. is increased to 627 oSt. When reaching 627 o3t the following were added: * '.

Sodium Hydroxide Solution (50 ^) 7.69

■. · This immediately reduces the viscosity} However, it was

continued heating at 80 ° C on viscosity Reached 550 East. Then they told lies

Water, 3.85

The resin is then completed by cooling to 20 ° Q. The finished resin had the following properties

Molar ratio of formaldehyde to phenol 2.25 * · 1 resin solids, # 43

■■ '■ i

Viscosity at 25 ° 0. 627 east Specific GsAoht. 25 ° / 25 ° 0 ^v 1.197 Example II

A second phenolic resin is produced through sales of the following substances in a resin container

,. BAD ΟΓν

809805/0615, *

U-21 472

-liMaterial parts by weight

Phenol (100 #) 26.63

Formaldehyde ( $ 37> unstabilized) 47.00
Sodium hydroxide solution (50? 6> 1.87

The above mixture is continuously stirred for 45 minutes

heated to 60 ° C, whereupon this temperature is maintained for 30 minutes. The temperature is then increased to 90 ° G
and maintained until a viscosity of 93 cSt at a
sample cooled to 25 ° C is obtained. Diö temperature
is then reduced to 80 ° 0 and maintained until the viscosity has reached 588 cSt. Then the following is added:

Sodium Hydroxide Solution ($ 50>) 8.41

* 1

Waeser 10.96 ■ [.

These additives reduce the viscosity up to about '■. 182c0t. The temperature is then maintained at 80 ° C to '' a Viekosität of 250 East is achieved, whereupon the temperature reduced tempera- \ to 75 ° C and is held there. So- i "

soon the viscosity reaches 330 cSt, are added »" - Γ

Sodium Hydroxide Solution (50 ^) 5 _f 13

The resin is then partially removed by removing water '* -. dehydrated under reduced pressure. A total of 7.94 parts; Water removed. The resin is then cooled to below 25 ° C. }

809805/0615

U-21 -12- -s

The finished resin has the following properties: Molar ratio of formaldehyde to phenol 2.04:

Resin solids, # 49.4

Viscosity at 25 ° C 500 cSt

Specific gravity 25 ° / 25 ° C 1.232

Example III

A phenolic resin is made by reacting the following ingredients in a resin kettle:

Material parts by weight phenol (90 ^) 38.79

Formaldehyde (46.5 ^) 44.42

Methyl cellulose 0.18 * "

Water 12:37

Sodium hydroxide solution (50 ^) 3.14

The above substances are brought up with continuous stirring 85 ° 0 heated in 100 minutes. The temperature is held at 85 ° G until the viscosity, measured at 25 ° C, is 200 cSt achieved. The temperature is then reduced to 80 ° C and held there until the viscosity reaches 884 cSt.

Then the following are added:
Sodium Hydroxide Solution (50-6) 1.10

809805/0615

1A-21 472

-13-

The pressure is then reduced and 1.5 parts of water are removed by dehydration. The resin is made by cooling completed to about 20 ° C.

The resin has the following properties:

Molar ratio of formaldehyde to phenol 1.85

Pestkörper, i * 50.3

Viscosity at 25 ° C. 1180 oSt Specific weight, at 25 ° / 25 ^ό 0 1.177

In each of the above examples, the viscosity measurement was carried out using a Gardner-Holdt bubble system, which is well known in resin manufacture. The viscosity values are determined by setting a resin sample to 25 ° C before the measurement (either the final resin or an intermediate sample).

The above examples are typical of various > alkaline phenol-formaldehyde resins which can be used in accordance with the invention for gluing plywood together. Other alkaline phenolic resins with slightly different properties, but a formaldehyde to phenol molar ratio between 1.5 1 and 3 1, are equivalent to those described.

The resins of Examples I, II and III can be used without modification by this new process for making plywood

809805/0615

U-21 472 -14- · _ν

* The resins are applied directly to the paper web, the moist paper web directly between the veneers to be joined are placed and the veneers are then pressed and heated.

While the resins described are used directly as adhesives- '| Preparation can be used, the performance is preferably improved by suitable additives.

The following examples show the production of improved adhesive formulations based on the resins of Example I, II and III.

Example 17 \ The resin is first placed in a mixing tank in it at vacancies ί and the additives shown below temperature solved. Weight parts f material 100 Resin according to Example II 5 '. ^l Sodium Hydroxide Solution (50 96) 2 sodium Example V

Resin according to Example II .100 'X ^:

Sodium Hydroxide Solution (50 fl) 5.

sodium

809805/06 1 5

Resorcinol paraformaldehyde

1A-21 472

Example VI

material Parts by weight Resin according to Example II TOO Sodium Hydroxide Solution (50 #) 5 I.
Sodium chromate
I. 1 Example VII

Resin according to Example I sodium hydroxide solution (50 Sodium chromate

100 5

0.5

Example VIII

Resin according to Example III sodium hydroxide solution (50% sodium carbonate

100 5 0.5

Example IX Parts by weight material 100 · Resin according to Example I. 5 Sodium hydroxide solution (50 ^) 1 sodium Example X

Resin according to Example III sodium hydroxide solution (50 sodium chromate

100 5 0.5

809805/0615

1A-21 472

-16-

The adhesive preparation can contain dry fillers in addition to the chemical additives. the The following adhesive preparations based on the resins of Examples I, II and III show the use of such dry filler. The resins, fillers, chemical additives and water are mixed until they are even and are free of lumps.

Example XI

Material parts by weight Mixed for 5 minutes 195 Water at 20 ° 0 HaTz according to Example I. Dry, finely ground residue Mixed for 5 minutes 100 from furfural production Mixed for 1 minute 50 Sodium Hydroxide Solution ($ 50) Mixed for 15 minutes 20th sodium 560

Water at 20 ° 0 _v 50

Mixed for 5 minutes

809805/0615

1A-21 472

-17- _ν \

Example XII . | Material parts by weight

Water at 20 ° C 202.5 γ ..

Finely ground walnut shell flour 115 pounds.

1 minute mixed _t t

■ * I

Sodium Hydroxide (Flakes - 100 #) 22.5. I.

Mixed for 15 minutes. t

Sodium carbonate 15

Mixed for 5 minutes

Resins according to Example I 550

Mixed for 5 minutes

Example XIII f _:

Sodium hydroxide solution (50 96) 560 '«*. ^l 'water at 85 ° C (185 ° F) 1200.

Mixed for 1 minute

Ground bark of Douglas pine 200

Mixed for 2 minutes

Sodium carbonate 200 .. \.

Heated to 87.8 to 93.4 ° ⁰ O 0 (190 ° F-200 ° F) [

Held for 20 minutes, then to 60 ° C f

(140 ° F) cooled. '')

Diesel oil 24 χ

Resin according to Example III added 2500 \

i. 5 minutes mixed up while cooling down. ;

26.7 ° C (80 ° ^) - '

809805/0615

1A-21 472

-18-

The adhesive preparation as shown in Example XII is applied according to the invention to a paper web. The damp web is placed directly between Douglas pine veneers and these veneers are then subjected to heat and pressure after various gluing periods.

Test pieces 25.4 χ 76.2 mm (1 "χ 3") are made from the obtained plywood and alternately boiled in water and dried according to the United Statte Commercial

for
Standards / exterior plywood, CS45-55 par. 5.3.2. Pie wet probes are subjected to a shear test (aheer) and the sruoh strength and the percentage bruoh are noted. The following table I shows the test results in detail.

Table I - ·

Board construction

56 Press conditions

Order in kg (pounds) ο Resin per 1000 sq. Ft. paper

Gluing time
(Minutes)

Testergebniaa · breaking strength- brittleness
(PSI) £

3-layer, 9.525 mm (3/8 ») dioke layers, pressed for 3 minutes at 12.95 kg / cnL (185 psi) at a" temperature of 148.9 ⁰ O (300 ⁰ F)

3.18kg (7.2)

kg / ciir

3 12.7 (.181) - 98

3 5.88 (84) '9a

12 100.49 (107) 99 *

12 11.69 (167) 97

20 11.48 (164) 97

'5-so-layered
20.638 mm 013/16 ") thick layers, -pressed 7 minutes at Tß, 95 kg / onr at (185 pei) at a temperature of 148.9 C (300Op)

3.53 kg (7.8)

12th 12th 20th 20th

6.79
6.79
6.44
8.47
5.88

97;

97

92 '

121)

84)

85 90 92 91 97

8 0 9805/0615

1A-21 472 · ·

-19-.

's-

The adhesive formulations of Example I to XI and Example XIII are also used for plywood manufacture used according to the invention, but a Haibautoma-. table lay-up system used;

The floor veneers are arranged so that they are continuous on a horizontally arranged chain (traveling chain) move. A first paper web is coated on both sides with the adhesive preparation, by running the paper continuously between two applicator rollers and then onto the moving ones Laying veneers as a continuous sheet. The speed of the web and the veneers is synchronized, so that a smooth sheet layer is obtained. A second veneer is applied to the adhesive sheet with its grain in brought at an angle to the floor veneer. A second adhesive-coated sheet is synchronized with the second veneer laid by forming a plywood subassembly. A third veneer is then added to the second Panel laid with its grain parallel to the first veneer. This forms a three-layer structure that is used for pressing is done.

The paper web bridging the gap between the successive moving veneers is through a moving high velocity air blast split before some of the glued

1 "

809805/0615

1A-21 472

-20-

Stacks parts for pressing. The web glued by others Parts are separated by a circular saw before stacking.

The glued pieces are then hot pressed to the

Adhesive preparation to harden and finished plywood sheets to build.

The finished sheets are then tested for bond strength and percent breakage in a similar manner

as in example XII. The results obtained are the same or the same as the plywood made by the usual methods think.

Optionally, two or more subassemblies can be stacked to make up any sheet of plywood To make thick sheets or a number of sheets. The last veneer on the pile will form the cover sheet that concludes the sheet. If one piles up the lower parts, 'so it is It is necessary to ensure that the grain of each successive pulp is at an angle to the grain of the next Veneer is laid.

Claims

809805/06 1 5

Claims (5)

DR. ING. F. WTJESTHOFF 8 MUNICH 90 DIPIi. ING. G. PULS SCHWEIGEHSTHASSE S DR.E.V.PECHMANN ^ LA tklkfojt 22 06 51 PATENTANWÄLTE Ύ tklkchammadkkssk, PHOTBCTPATJBJTT MUKCHXK 1A-21 472 July 15, 1968 Patent claims 1.) Process for the production of laminates by hot pressing a paper web impregnated with an aqueous alkaline phenol-formaldehyde-containing adhesive solution between layers of the materials to be joined, for example wood veneers, the adhesive preparation having a formaldehyde-phenol molar ratio between 1.5 ι 1 and 3x1 and has been uniformly applied to the absorbent paper web at a speed of at least 1.36 kg resin solids per 92.9 m paper web, characterized in that, that the resin-containing paper web is placed moist between the layers and then hot-pressed without prior significant reduction in the moisture of the adhesive preparation. 2. Method according to claim 1, characterized in that g e k e η η - draws that one has the adhesive formulation on both sides the paper web applies. 3. The method according to claim 1 or 2, characterized in that wood veneers are used as layers. 4. The method naoh claim 3, characterized g e k β η η - ' draws that you first have a series of tournaments, ;, JUQ documents (Art 7 <5I Abs, 2 Nr. 1 Sfrtz 3 daa amendment yyes. V. 4,9.19C. ⁷ ' 1A-21 472 ' -22- which abut one another, moved in an ordinary, substantially horizontal path, then continuously this row of veneers lays the first absorbent paper web onto which resin-containing adhesive has been applied then applies a second sequence of veneers to the first row of veneers and paper web, the grain being angular With regard to the grain of the first sequence, then on the second row of veneers there is a continuous second absorbent Paper web lays on which the resinous adhesive preparation has been applied, and forms sub-structures from the first and second row of veneers and paper webs, by dividing the sheets and veneers at the interface between the veneers of the first series, and a plywood structure by placing a face veneer on each sub-structure the grain of which is essentially unidirectional the grain of the first sequence of veneers, and heats and presses this sheet of plywood to solidify and glue it 5. The method according to claim 3, characterized in that one first moves a sequence of veneers that abut one another in a customary, substantially horizontal path, then a first absorbent paper web is continuously placed on the veneer a resin * ~. _ν containing adhesive has been applied, this first row of veneers and paper web with a second row of fur- 809805/0615 1A-21 472 -23- kidneys whose grain is oriented at an angle with respect to the grain of the first row, then continuously a second absorbent paper web is placed on top of the second row of purées, on which a resinous Adhesive formulation has been applied, and then made from the first and second series of veneer and paper webs The substructure is formed by placing the paper webs and veneers at the interface between the veneers of the first The sequence divides, then the first veneer of a structure is placed on the second sheet of a second structure, then one Cover veneer on the topmost paper web with the grain of each veneer at an angle to the grain of the next Laying veneers and heating and pressing the veneers and paper webs for Verfestlgüng and gluing. 809805/0615