PL236050B1 - Application of poly(hydroxyoxetanes) and hot-melt adhesive for wood - Google Patents

Description

Description of the invention

The present invention relates to the use of poly (hydroxyoxetanes) for gluing wood.

Hot melt adhesives form a joint by solidification upon cooling. They are applied to the substrate in liquid form, and a permanent adhesive bond is obtained by exerting pressure on the other element to be glued. Alternatively, the adhesive is applied between the surfaces to be glued in the form of an adhesive sheet and the pressure is exerted by the heating element of the press. It is also possible to apply the glue in the form of drops or glue thread to the surface to be glued (e.g. veneer), and then to liquefy the glue under the influence of hot air or heating elements of the press.

The hot melt adhesives used in wood technology usually contain a thermoplastic polymer as a base substance and auxiliary agents such as melt point and viscosity reducing resins, antioxidants and fillers. Typical thermoplastic polymers used in hot melt adhesives for the furniture industry are: ethylene vinyl acetate copolymers, polyethylene terephthalate, amorphous poly-a-olefins, polyamides and polyurethanes.

Most of the non-reactive hot melt adhesives available on the market require a high application temperature - above 150 ° C.

The descriptions of patent applications describe poly (hydroxyoxetanes) obtained by cationic polymerization catalyzed by Lewis acids, halides of inorganic acids or Bronsted acids [1,2]. There are also poly (hydroxyoxetanes) obtained by anionic polymerization with the use of sodium hydride as a catalyst and benzyl alcohol or trimethylolpropane as a co-initiator [3]. Properties of the poly (hydroxyoxetanes) being the subject of the invention have been described in the scientific literature [4,5,6] and in the patent application [1]. Due to the large number of hydroxyl end groups in the branched structure, poly (hydroxyoxetanes) have potential use as macro-initiators of anionic or cationic polymerization of ethylene oxide [7], anionic-coordination polymerization of L, L-lactide [8], as well as ATRP polymerization of styrene or acrylates [5,9,10,11]. Literature reports also indicate the potential use of poly (hydroxyoxetanes) as modifiers of inorganic surfaces [12] and as materials for the formation of nanocomposites [13].

According to the present invention, poly (hydroxyoxetanes) have been used to prepare a hot-melt adhesive that allows the gluing process to be carried out at a temperature lower than that of adhesives used so far.

The invention is based on the use of branched poly (hydroxyoxetanes) with the structure illustrated by the general formula 1, in which R is ethyl, and with an average molecular weight in the range Mn = 500-10,000, alone or with the addition of adjuvants, as wood hot melt adhesives.

Preferably, poly (hydroxyoxetanes) with a degree of branching in the range DB = 0.25-0.5 are used.

Preferably poly (hydroxyoxetanes) with an average molecular weight in the range Mn = 1000-4000 are used.

Preferably, the poly (hydroxyoxetanes) are used singly or in a mixture of at least two poly (hydroxyoxetanes) differing in their β-position alkyl substituent with respect to the oxygen atom of the repeat unit and / or the average molecular weight.

Preferably, poly (hydroxyoxetanes) are used with the addition of adjuvants, which are hydrocarbon resins, waxes, antioxidants and fillers, in a total amount of at most 40 wt.%.

Branched polymers exhibit a lower viscosity than their linear analogs of the same molecular weight. The reduced viscosity of the polymers has a positive effect on the penetrating properties of the adhesive. Statistically highly branched polymers achieve a degree of branching, DB = 0.5. With an increase in the number of linear units in the structure, the branching degree value decreases to 0. Therefore, poly (hydroxyoxetanes) are used with a branching degree of DB = 0.25-0.5.

Poly (hydroxyoxetanes) is used with the addition of adjuvants, which are hydrocarbon resins, waxes, antioxidants and fillers. When poly (hydroxyoxetane) is used with the addition of adjuvants, the proportion of poly (hydroxyoxetane) in the adhesive is at least 40% by weight.

The polyhydroxyoxetanes of the invention are obtained by the cationic ring-opening polymerization of 3-methyl-3- (hydroxymethyl) oxetane or 3-ethyl-3- (hydroxymethyl) oxetane. The polymerization reactions of 3-methyl-3- (hydroxymethyl) oxetane and 3-ethyl-3- (hydroxymethyl) oxetane are catalyzed by Lewis acid - boron trifluoride ethyl ether BFs ^ O (C2Hs) 2. 3-methyl-3 polymerization

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- (hydroxymethyl) oxetane is preferably carried out in methylene chloride solution at -2 ° C for 24 hours. The degree of branching is determined by the monomer / catalyst molar ratio. A higher monomer / catalyst molar ratio leads to polymers with a more branched structure (Table 1). The dependence of the degree of branching on the reaction temperature has been described in detail by Maja and co-authors in: Effect of Reaction Temperature on Degree of Branching in Cationic Polymerization of 3-Ethyl-3- (hydroxymethyl) oxetane [14], In the case of 3-ethyl-3 polymerization - (hydroxymethyl) oxetane, the number of branches is determined by the reaction temperature (Table 2). The polymerization of 3-ethyl-3- (hydroxymethyl) oxetane is preferably carried out in a methylene chloride solution for 24 hours for a constant catalyst / monomer molar ratio of 0.5. The dependence of the degree of branching on the catalyst / monomer molar ratio was described by Yan and co-authors in the publication: A new approach to control crystallinity of resulting polymers: Self-condensing ring opening polymerization [6],

Table 1

Monomer Reaction temperature The degree of branching DB 3-ethyl-3- (hydroxymethylene 1 o) oxetane 30 ° C 0.42 10 ° C 0.39 0 ° C 0.35 -8 ° C 0.29 -30 ° C 0.17

Table 2

Monomer Monomer / catalyst molar ratio The degree of branching DB 3-methyl-3 (hydroxy methyl 3o) oxetane 200: 1 0.23 100.1 0.25 2: 1 0.34

Disclosed is a hot melt wood adhesive containing at least one branched poly (hydroxyoxetane) of the general formula I, wherein R is as defined above, in an amount of from 40 to 100 wt.%. and auxiliary substances in a total proportion of 0 to 60% by weight The auxiliary substances are selected from the group consisting of: fillers, additives improving the rheological properties of adhesives, surfactants improving the miscibility of the formulation ingredients and antioxidants.

As fillers, the adhesive may contain mineral fillers such as barium sulfate, calcium carbonate, silica, talc, in an amount not exceeding 40% by weight.

The following may be used as additives improving the rheological properties of adhesives: hydrocarbon waxes, polyterpenes, rosin and its derivatives, polyethers and their derivatives, in an amount not exceeding 40% by weight.

As antioxidants, the adhesive may contain Irganox1010, butylated hydroxytoluene (BHT), distearyl thiodipropionate (DSTDP), or polyphenolic compounds such as 1,3,5-trimethyl 2,4,6-tris (3,5-di-tert-butyl-) 4-hydroxybenzyl) benzene) (TDTHB) in an amount not exceeding 2 wt.%.

The disclosed adhesive is obtained by melting polyoxetane or a mixture of polyoxetanes in a mixer at a temperature of 140 to 210 ° C and then introducing the remaining adhesive components.

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The ingredients are mixed until homogeneous. Then the adhesive mass is directed to the extruder for thermoforming the commercial form, i.e. sticks, sheets, granules, or it is applied to a carrier (decorative papers, films, artificial veneers).

The ready-to-use adhesive is applied to a carrier, such as e.g. films, laminates, artificial and natural veneers, at a temperature of 80 to 190 ° C. The pressing of the prepared veneer is carried out with a minimum pressing time of 20 s and a minimum press temperature of 80 ° C. Alternatively, the glue in the form of sheets is placed between the materials to be glued, which are pressed in a hot or cold press, when the pressing step is preceded by plasticizing the glue sheet by blowing hot air.

Thermoplastic branched poly (hydroxyoxetanes), as the basic substance of hot melt adhesives, are characterized by high adhesion to materials used in wood and furniture technology. The use of hot-melt glue based on polyoxetanes enables gluing processes to be carried out at a temperature lower than that typical for hot-melt adhesives, i.e. <150 ° C, and in special cases even below 100 ° C, which significantly reduces the energy demand of the process. The polyoxetane-based adhesives also have high strength of joints, in special cases reaching 7-8 MPa.

The disclosed hot-melt adhesive can be used in particular for covering wide and narrow edges of furniture boards with thermoplastic films, laminates or natural veneers and for joining solid wood elements.

Execution examples.

Example 1, (OX1).

30.59 g (215.5 mmol) of boron trifluoride diethyl ether and 300 ml of dichloromethane were placed in a 1000 ml three-necked round bottom flask equipped with a magnetic stirrer, heating mug, septum, dropping funnel and thermometer. 50.0 g (431.0 mmol) of 3-ethyl-3- (hydroxymethyl) oxetane was placed in the addition funnel. The reaction system was argon flushed for 20 minutes before the monomer dropwise began. The monomer was dosed in portions to the reaction system over one hour. The reaction was carried out under an inert gas stream at 30 ° C for 48 hours. The catalyst was deactivated with ethanol. The obtained poly (3-ethyl-3-hydroxymethyloxetane) was precipitated in cold diethyl ether and then dried under reduced pressure of 10 Torr at 60 ° C for 10 h. The reaction yield was 64%. The degree of branching of OX1 is 0.42 and the molecular weight Mn = 1950.

Example 2, (OX2).

12.24 g (86.2 mmol) of boron trifluoride diethyl ether and 80 ml of dichloromethane were placed in a 250 ml three-necked round bottom flask equipped with a magnetic stirrer, heating mug, septum, dropping funnel and thermometer. 20.0 g (172.4 mmol) of 3-ethyl-3- (hydroxymethyl) oxetane was placed in the addition funnel. The reaction system was argon flushed for 20 minutes before the monomer dropwise began. The monomer was dosed in portions into the reaction system over 10 minutes. The reaction was run under an inert gas stream at -8 ° C for 48 hours. The catalyst was deactivated with ethanol. The obtained poly (3-ethyl-3-hydroxymethyloxetane) was precipitated in cold diethyl ether and then dried under reduced pressure of 10 Torr at 60 ° C for 6 hours. The reaction yield is 89%. The degree of branching of OX2 is 0.29 and the molecular weight Mn = 3200.

Example 3, (OX3).

The reaction was carried out analogously to Example 2, except that the reaction temperature was 10 ° C. The reaction yield is 99%. The degree of branching of OX3 is 0.39 and the molecular weight Mn = 2460.

Example 4, (OX4).

The reaction was carried out analogously to Example 2, except that the reaction temperature was 0 ° C. The reaction yield is 99%. The degree of branching of OX4 is 0.35 and the molecular weight Mn = 2700.

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Adhesives having the compositions shown in Table 3 were prepared from the poly (hydroxyoxetanes) prepared in accordance with Examples 1-4.

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Table 3

Glue Composition (parts by weight) KI ΟΧ1 - 100 K2 ΟΧ1 -98, Irganoxl010 - 2 K3 ΟΧ1 - 33, ΟΧ3 - 33, ΟΧ4 - 34 K4 ΟΧ1 - 80, silica - 10, rosin - 8, Irganoxl010 - 2. K5 ΟΧ3 - 30, 0x4 - 40, barium sulfate - 20, Clearon® polyterpene P-115-8, BHT-2 K6 ΟΧ1 - 33, ΟΧ2 - 33, ΟΧ4 - 7, talc - 9, Epolene E-10 - 8, Epolene N-34P - 7, TDTHB - 2 K7 ΟΧ2 - 75, 0x3 - 7, Silica - 8, Epolene E14EP - 8, DSTDP - 2 K8 0x2 - 70, 0x4 - 10, talc - 4, silica - 6, polyglycerol - 8, lrganoxl010 - 2.

The K1-K8 adhesives were tested as described in the examples below. The tear-off strength test of the refining layer was carried out in accordance with PN-EN 311 [18], and the results were compared with the requirements of PN-EN 312 [19],

Example 6

The K1 adhesive film with a thickness of 0.5 to 1.0 mm was placed between the chipboard and the HPL laminate and the whole was pressed in a press at a temperature of 95 ° C, for 60 seconds, under a pressure of 1.5 N / mm ² . The connection met the requirements of PN-EN 312.

Example 7

The K2 adhesive film with a thickness of 0.5 to 1.0 mm was placed between the MDF and the HPL laminate and the whole was pressed in a press at the temperature of 95 ° C, for 60 s, under the pressure of 1.5 N / mm ² . The connection met the requirements of PN-EN 312.

Example 8

The K3 adhesive film, 0.5 to 1.0 mm thick, was placed between the blockboard and 1.0 mm thick natural oak veneer, and the whole was pressed in a press with a temperature of 130 ° C for 30 s under a pressure of 1.5 N / mm ² . The connection met the requirements of PN-EN 312.

Example 9

The film of K4 glue with a thickness of 0.5 to 1.0 mm was placed between a natural oak veneer with a thickness of 1.0 mm and an MDF board and pressed in a press at a temperature of 130 ° C, for 50 s, under a pressure of 1.5 N / mm ² . The connection met the requirements of PN-EN 312.

Example 10

The 0.5 mm thick K2 glue film was placed on the surface of 5 mm solid birch wood lamellas, exposed to air at 190 ° C for 40 seconds, then a second lamella was pressed against the plasticized glue layer with a pressure of 1.0 N / mm ² within 60 s. The shear strength of the adhesive joint was over 6 N / mm ^2, determined in accordance with the EN205 standard. An analogous test performed with a commercial hot-melt adhesive showed a bond strength of 2.4 N / mm ² .

Example 11

The film of K7 glue with a thickness of 0.5 mm was placed between two lamellas of solid birch wood with a thickness of 5 mm, pressed in a press at a temperature of 190 ° C for 40 seconds, then the second lamella was pressed against the layer of plasticized glue with a pressure of 1.0 N / mm ² in 60 s. The shear strength of the adhesive joint exceeded 7 N / mm ^2, determined according to the EN205 standard.

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An adhesive layer K6 less than 0.5 mm thick was applied and solidified by cooling on a beech veneer with a thickness of 2.0 mm. Three veneers were pressed in layers in a press with a temperature of 160 ° C, during 35 s, under a pressure of 1.0 N / mm ² . The joint strength was 3.5 N / mm ² .

P r x l a d 13

The HPL laminate with the previously applied and solidified by cooling the layer of K7 glue was pressed onto the blockboard in the press at the temperature of 130 ° C, for 50 s, under the pressure of 1.5 N / mm ² . The connection met the requirements of PN-EN 312.

P r z k ł a d 14

The layer of K5 glue, previously applied and solidified by cooling on 2.0 mm thick beech veneer, was exposed to air at a temperature of 190 ° C for 45 seconds, then the material was pressed onto the blockboard with a pressure of 1.5 N / mm ² for 60 s. The connection met the requirements of PN-EN 312.

P r z k ł a d 15

The ABS edging tape with the previously applied and solidified by cooling the layer of K8 glue was exposed to air at a temperature of 190 ° C and pressed against the narrow plane of the chipboard with a pressure of 1.5 N / mm ² for 60 seconds. The connection met the requirements of PN-EN 312 .

P r z k ł a d 16

The PVC edging tape with the previously applied and solidified by cooling the layer of K6 glue was exposed to air at a temperature of 190 ° C and pressed against the narrow MDF plane with a pressure of 1.5 N / mm ² for 60 seconds. The connection met the requirements of PN-EN 312 .

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Claims (5)

Patent claims CLAIMS 1. Use of branched poly (hydroxyoxetanes) of the structure illustrated by the general formula 1, in which R is an ethyl group, with an average molecular weight in the range M _n = 500-10,000, alone or with the addition of adjuvants, as wood melting adhesives. 2. Use according to claim 1 The process of claim 1, wherein the poly (hydroxyoxetanes) is used with a degree of branching in the range DB = 0.25-0.5. 3. Use according to claim 1 The process of claim 1 or 2, characterized in that poly (hydroxyoxetanes) with an average molecular weight in the range M _n = 1000-4000 are used. 4. Use according to claim 1 The method of claim 1, wherein the poly (hydroxyoxetanes) are used alone or in a mixture of at least two poly (hydroxyoxetanes) differing in the alkyl substituent in the β position with respect to the oxygen atom of the repeating unit and / or the average molecular weight. 5. Use according to claim 1 The process of claim 1, characterized in that the poly (hydroxyoxetanes) is used with the addition of adjuvants, which are hydrocarbon resins, waxes, antioxidants and fillers, in a total amount of at most 40 wt.%.