JPS5924769A - Crosslinking film shaped adhesive for bonding of wood - Google Patents

Abstract

PURPOSE:To provide a crosslinking film-shaped adhesive which can be used in bonding under heat and pressure and has excellent hot water resistance, prepared by introducing a silanol condensation catalyst into a film formed from a copolymer of ethylene, an ethylenically unsaturated silane compd. and other ethylenically unsaturated compds. CONSTITUTION:A copolymer consisting of (A) ethylene, (B) ethylenically unsaturated silane compd. (e.g. vinyltrimethoxysilane) and (C) other ethylenically unsaturated compds. (e.g. vinyl acetate or methyl acrylate) and containing (B) and (C) in 0.01-5 and 10-40wt%, respectively, based on the copolymer, is formed into film in the thickness of 20-200mu. The titled film-shaped adhesive is obtained by introducing 0.001-10wt% silanol condensation catalyst (e.g. dibutyltin dilaurate) into the film.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a film-like crosslinkable adhesive for bonding wood.

Adhesives made of thermosetting resins such as phenolic resin, urea resin, and melamine resin, which have traditionally been used for plywood, laminated wood, woodwork, etc., require long bonding times to harden the thermosetting resin, which is the main component. 〇On the other hand, thermoplastic resins such as vinyl acetate resin, ethylene-vinyl acetate copolymer resin, etc. The adhesive consists of
In the emulsion type, the above-mentioned drawbacks of thermosetting resins have not been sufficiently eliminated, and the hot water resistance is poor.
In addition, although pot-melt type resins do not have the disadvantages of thermosetting resins mentioned above, they must have a melting point at a temperature h (usually about 110°C or less) that does not cause deterioration or deformation of the adhered wood. Inevitably, hot water resistance is inferior.

On the other hand, as an adhesive that combines the hot water resistance of a thermosetting resin adhesive and the simplicity of the bonding process of a hot-melt thermoplastic resin adhesive, we have added crosslinking properties to a thermoplastic resin adhesive in the form of a film. However, attempts have been made to improve hot water resistance by crosslinking the resin after adhesion. Specifically, for example, an ethylene-vinyl acetate copolymer resin is grafted with an ethylenically unsaturated silane compound such as vinyltrimethoxysilane using a radical generator to obtain a silane-modified resin, and a silanol condensation catalyst is blended with it. The composition is formed into a film, and after adhesion, the resin is crosslinked by contacting it with moisture. However, in this method, crosslinking of the paste resin inevitably occurs due to the radical generator during the grafting reaction, so the resulting film formed from the silane-modified resin has a large amount of fish eyes.
There are problems such as poor adhesive strength as an adhesive and unevenness appearing on the surface of the adhered product.

In view of the above points, the present invention has been developed to form a film for adhering wood that can be heat-pressed at a temperature of 110°C or lower, exhibits excellent hot water resistance by crosslinking, and does not cause fish eyes. This invention was made for the purpose of providing a crosslinkable adhesive, and as detailed below, the present invention is a copolymer of ethylene, an ethylenically unsaturated silane compound, and another ethylenically unsaturated compound, , the content of ethylenically unsaturated silane compound units and the content of other ethylenically unsaturated compound units are based on the weight of the copolymer, respectively, 0.01 to 5M, and 1O to 40%, respectively.
% copolymer is formed into a film having a thickness of 20 to 200 μm, and then a 7-lanol condensation catalyst is introduced into the film to form a film-like crosslinkable adhesive for bonding wood.

The ethylenically unsaturated silane compound used in the copolymer of ethylene, ethylenically unsaturated silane compound, and other ethylenically unsaturated compound in the present invention has the general formula 几Si几nYg-口 (Here, It is ethylenically unsaturated hydrocarbon group or hydrocarbonoxy group,
R is an aliphatic saturated hydrocarbon group, Y! -, represents a hydrolyzable organic group, and n is 0, 1 or 2. ) refers to a silane compound represented by
For example, ■ is also cahinyl, allyl, isoflobenyl, futhynyl, cyclohexenyl, γ-(meth)acryloyloxypropyl, I'L is methyl, ethyl, propyl, decyl, phenyl, Y is methoxy, ethoxy, formyloxy, acetoxy, Propionyloxy, alkyl or arylamino. IV! CH2=C) Is i (OA) s (where A is a carbon number of 1 to 80).hydrocarbon group. ), specifically vinyltrimethoxysilane, vinyltriethoxysilane, and
It is vinyltriacetoxysilane. These ethylenically unsaturated silane compounds may be used in combination with two or more extractions, if necessary.

The content Rt of the ethylenically unsaturated silane compound unit is:
Based on copolymer weight @0. (It is essential that the amount is 11 to 5% by weight, and it is preferable that the amount be in the range of 005 to 21%. If it is less than 0.01% by weight, the hot water resistance will be insufficient even if crosslinked, and the amount will be less than 5% by weight. If the amount is too high, fish eyes will appear on the film, making it difficult to consistently obtain good adhesive strength.

Other ethylenically unsaturated compounds used in the present invention include (a) vinyl esters such as vinyl acetate and vinyl butyrate and vinylpepiparate; (b) (meth)
Metinope acrylate (meth)acrylic acid esters such as ethyl (meth)acrylate and butyl (meth)acrylate; (iii) unsaturated carboxylic acids such as (meth)acrylic acid, maleic acid, and fumaric acid; (meth)acrylic acid □nR forms such as (meth)acrylonitrile and (meth)acrylamide; vinyl ethers such as (e)vinyl methyl ether and vinyl phenyl ether; and the like. Preferred among these are (
meth)acrylic acid ester! 1 to 4 carbon atoms
(meth)acrylic acid ester having an argyl group, such as methyl (meth)acrylate. In addition, these other ethylenically unsaturated compounds preferably have a low free acid content in order to suppress the occurrence of fish eyes in the copolymer film;
PPm or less, especially Vi50 P Prn or less. In addition, [(meth)acrylic acid" shall mean both acrylic acid and methacrylic acid. Such ethylenic The unsaturated compound may be used in combination with 2, 1jJj or more if necessary, and the amount of the other ethylenically unsaturated compound units is:
It is essential that the amount is 10 to 40% by weight, based on the weight of the copolymer, and preferably 15 to 30% by weight and 13t%. 10] When the amount of i is less than %, it becomes impossible to heat and press at a temperature of 110° C. or less, and when it is more than 40% by weight and 14%, the strength of the adhesive itself decreases.

The copolymerization of ethylene with the ethylenically unsaturated silane compound and other ethylenically unsaturated compounds may be carried out under any conditions that allow copolymerization of the three components.

Specifically, for example, the pressure is 500 to 4,000, the pressure is 1,000 to 3,500'! 4. Temperature 100~
under conditions of 400° C., preferably 150 to 350° C., in the presence of a radical polymerization initiator and, if necessary, a chain transfer agent, in a seed or tubular reactor, preferably a seed reactor,
Each individual juvenile is contacted simultaneously or in stages.

In the present invention, any radical polymerization initiator and chain transfer agent known for use in homopolymerization or copolymerization of ethylene can be used. Examples of the polymerization initiator include lauroyl peroxide, difluorobionyl peroxide, benzoyl peroxide, di-t-butyl peroxide, [-butyl hydroperoxide, t-
These include organic peroxides such as butyl peroxyisobutyrate, molecular oxygen, and azo compounds such as azobisisobutyronitrile and azoisobutylvaleronitrile. Chain transfer agents include methane, ethane, propane, butane,
Paraffinic hydrocarbons such as pentane, α-olefins such as propylene, butene-1, hexene-1,
Examples include aldehydes such as pormaldehyde, acetaldehyde, and n-butyraldehyde, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, aromatic hydrocarbons, and chlorinated hydrocarbons.

In the present invention, in order to form the copolymer into a 7.rlum, various auxiliary materials may be added to the co-jf3 combination as necessary, such as ester compounds such as fatty acid esters, nitrile compounds such as hexane nitrile and benzonitrile, Isocyanate compounds such as methylene bis(4-phenyl isocyanate), polyincyanate, the reaction product of tolylene diisocyanate and hexanetriol, etc., adhesion promoters, mixable thermoplastic resins, stabilizers, lubricants, fillers,
A composition containing a colorant and the like can be formed using a known film forming method, such as an inflation method or a 'V die method.

The thickness of the film to be formed must be 20 to 200μ, preferably 50 to 150μ.
If it is thinner than μ, the adhesive strength will be insufficient, and 17'c200
If it is thicker than μ, it will be difficult to control the heat and pressure bonding force.

In the present invention, the object of the present invention cannot be achieved if the silanol condensation catalyst used as a crosslinking catalyst for this type of silane-modified resin is blended into the composition before film formation. It is essential to introduce it. Methods of introduction include a method of applying a solution or dispersion of a silanol condensation catalyst to a film or an adherend, a method of immersing a film or an adherend in a solution or dispersion of a silanol condensation catalyst, etc.
The surface of the formed film may be brought into contact with the silanol condensation catalyst.

As the silanol condensation catalyst, the present invention generally targets catalysts that can be used to completely promote dehydration condensation between silanols of silicone. Such silanol condensation catalysts are generally carboxylic acid compounds of metals such as tin, zinc, iron, lead, cobalt, organic hydrochloric acids, inorganic acids, and organic acids.

Specific examples of silanol condensation catalysts include dibutyltin dilaurate, diptyltin diacetate, dibutyltin dioctoate, dioctyltin dilaurate, stannous acetate, stannous caprylate, lead naphthenate, zinc caprylate, cobalt naphthenate, Inorganic acids, such as ethylamine, dibutylamine, hexylamine, pyridine, sulfuric acid, hydrochloric acid, etc.)
・There are organic acids such as luenesulfonic acid, acetic acid, stearic acid, and maleic acid. Among these, tin carboxylic acid compounds are preferred.

The required amount of the furanol 1411 cocatalyst may be appropriately determined by the practitioner for a given copolymer and a given catalyst, with reference to actual examples described later. Generally speaking, 0. (about 101 to 10M amount, preferably 1.
<0.01 to 5 weight ratio, particularly preferably 0.01 to 3
It's the weight clerk.

The film-like cross-linkable adhesive for bonding wood of the present invention is sandwiched between wood and water, or wood and various materials other than wood, and is pressed at a temperature above the melting point of the copolymer and below 110°C. At the same time, by crosslinking the copolymer to a total gel fraction of 5 to 90, preferably 10 to 80, by moisture in the air and moisture in the wood, a wood adhesive structure with excellent hot water resistance can be obtained. It is something that can be done.

The present invention will be described in more detail below with reference to Examples.

Production of the copolymer A mixture of ethylene, vinyltrimethoxysilane and/or methyl acrylate or vinyl acetate, and propylene as a chain transfer agent is fed into a stirred autoclave with an internal volume of 1.5 liters and a polymerization initiator is added. as t-
Add butyl peroxyisobutyrate (-1, under the conditions of pressure 2.6002i and temperature 210℃, ethyl peroxyisobutyrate
ethylene-vinyltrimethoxysilane-methyl acrylate copolymer (copolymers I to III), ethylene-vinyltrimethoxysilane-vinyl acetate copolymer (copolymer 1 [copolymer ■)],
Ethylene-vinyltrimethoxysilane copolymer (copolymer ■), ethylene-methyl acrylate copolymer (copolymer 1[
Each of the combinations (1) and 2) was produced continuously. Table 1 shows the polymerization conditions and physical properties of the copolymer.

Example 1 Copolymer II was molded using a T-die film molding machine (extruder 65 rule φ, T-die effective width 8θOmm) at a resin temperature of 2.
It was molded into a film with a thickness of 60 μm at 30° C. and a molding speed of 30 m/min. Diptyltin dilaurate as a silanol condensation catalyst was applied as a 0.1 weight percent ethyl alcohol solution to both surfaces of this film using a roll coating method, and then dried with a hot air dryer at 60°C to form a film-like crosslinkable adhesive. .

Next, prepare a birch veneer (moisture content: 8 layers) sliced into 1,0+ nm slices, and apply the previously obtained film-like crosslinking adhesive to this veneer to form a 3-ply plywood at right angles. Place between plates and heat press at 100°C with a pressure of 10 kg.
/ After crimping with Cta for 3 minutes, soak in room temperature water (approx. 18℃)
It was cooled for 3 minutes at a pressure of 10'9/cA in a cold press. As described above, orthogonal 3-ply cover plywood with a thickness of about 3.1 mm was created.

Visual observation results of the presence or absence of fish eyes in the previously obtained film, orthogonal 3-ply cut (visual observation results of the presence or absence of deformation of the wood in the plywood, measurement results of the gel fraction of the adhesive, measurement results of the adhesive strength of the plywood) is shown in Table 2VC.

In addition, the adhesive strength is based on the JAS general purpose board standard, by penetrating the core into a piece of plywood with a length of 75 mm and a width of 25 mm, and making a notch that reaches the adhesive area e at a distance of 13 mm from the front and back surfaces in the width direction. The test piece is used as a test piece, and the test piece is immersed in 60 weight 3°C warm water for 3 hours, and then immersed in room temperature water until it cools down. 145 The test was carried out by pulling the test piece in the same state (warm and cold water immersion test) at a loading rate of 600 kg per minute or less in the direction of both ends, and measuring the maximum load at the time of failure.

Examples 2 to 5 In Example 1, copolymer III was used instead of copolymer II.
(b for l-, film thickness 20μ (Example 2), 6
0 μ (Example 3), 120 μ (Example 4), 200 μ (
A birch plywood was produced in the same manner as in Example 1, except for the changes in Example 5).

The results are shown in Table 2.

Example 6 A cut plywood was produced in the same manner as in Example 1, except that copolymer (1) was used instead of copolymer (H). The results are shown in Table 2.

Example 7.8 In Example 1, a solution of the silanol condensation catalyst was applied,
After drying, the surface is further coated with 1 of an incyanate compound (Millione, manufactured by Nippon Polyurethane Co., Ltd.).
8 by applying 0 weight head ethyl acetate solution by roll coating method.
Plywood was prepared in the same manner as in Example 1, except that it was dried with hot air at 0°C.

(Example 7) In addition, in Example 7, the heat press temperature was changed to 90° C. to create birch plywood. (Example 8) The results are shown in Table 2.

Example 9 In Example 1, instead of applying the silanol condensation catalyst solution to the film, the contact surface of the birch veneer with the film (:
A birch plywood was prepared in the same manner as in Example 1, except that K was coated on both sides of the middle plate of the 1-ply plywood and on one side of each outer plate.

The results are shown in Table 2.

Comparative example 1 In Example 1, instead of copolymer
Example 1 was used, except that a vinyltrimethoxysilane-crafted ethylene-C12 vinyl copolymer (containing vinyltrimethoxysilane 1 ft 1.0% by weight) was used, which was obtained by grafting vinyltrimethoxysilane onto the ethylene-vinyl acetate copolymer. In the same way, birch plywood was made. The results are shown in Table 2.

Comparative Examples 2 to 6 In Example 1, instead of copolymer H, a mixture of copolymer V and copolymer
), Copolymer ■ (Comparative Example 3), Copolymer V (Comparative Example 4)
), Copolymer I (Comparative Example 5) was used, but birch plywood was produced in the same manner as in Example 1. In addition, in Comparative Example 5, the heat press temperature was changed to 120° C. to create birch plywood. (Comparative Example 6) The results are shown in Table 2.

Example 10 A film-like crosslinkable adhesive was obtained in the same manner as in Example 3, and this was applied to a birch veneer with a length of 70 mm, a width of 25 mm, and a thickness of 11 mm.
Same length and width, lauan plywood with a thickness of about 3m (JASI type approved product), particle board with a thickness of about 5wn, thickness 2
WI+ aluminum plate, 2mm thick iron plate, thickness approx.
Sushi slate board, sandwiched between 1 sheet thick phenol packer plate and 25 mm overlapped in the overall length direction, 100
Pressure 10 KGI/c++t at ℃ heat press 3
After pressing for a minute, six types of laminates were created by cooling with a cold press. Table 3 shows the measurement results of the adhesive strength of the A/I layer board.

In addition, the adhesive strength was determined by using a test piece of lauan plywood (JASI class passed product) with a thickness of about 1 mm attached to the surface of the cover veneer of the laminate with an epoxy resin adhesive and reinforcing it. Example II/Worked in a similar manner to that described herein.

Comparative Example 8.9 In Example 1O, copolymer ■ (Comparative Example 8) and copolymer V (Comparative Example 9) were used instead of copolymer I11,
In addition to creating a laminated board of cover veneer and aluminum board,
The procedure was the same as in Example 1o. The results are shown in Table 3.

Table 3 Patent 11 Smallholder Mitsubishi Yuka Co., Ltd. Representative Patent Attorney Hidetoshi Furukawa (1 other person)

Claims (1)

[Claims] A copolymer of ethylene, an ethylenically unsaturated silane compound, and another ethylenically unsaturated compound, in which the content of ethylenically unsaturated silane compound units and the content of other ethylenically unsaturated compound units are copolymerized. Wood glue made by forming a copolymer of 001 to 5 layers and 10 to 40% by weight, respectively, into a film with a thickness of 20 to 200μ based on the 1st limit of coalescence, and then introducing a silanol condensation catalyst into the film. A film-like cross-linking adhesive for use.