MXPA97009137A - Polymeric composition of two components - Google Patents

Abstract

The present invention relates to: A package containing components A and B, wherein component A contains: Ai) a solution or dispersion consisting of a polymer containing units with hydroxyl groups, and Aii) a polymer containing units with carboxyl groups, component B consists of Bi) in a polyfunctional crosslinker capable of crosslinking with at least one carboxyl group and at least one hydroxyl group. Components A and B can provide an adhesive, especially for wood substrates. Components A and B can also be used to form protective coatings on wood substrates. Examples of components Ai) include polyvinyl alcohol solutions, or dispersions of other polymers such as polyvinyl acetate / ethylene vinyl acetate in polyvinyl alcohol. Suitable components Aii) include the carboxylated styrene-butadiene rubber latex. Component A may also include fillers, for example to improve water resistance. The crosslinker can be a polyfunctional aziridine as one of Formula (I), wherein R is a polymer chain and Y is a lower alkyl group of 1 to 4 carbon atoms

Description

POLYMERIC COMPOSITION DB TWO COMPONENTS The present invention relates to compositions that are especially suitable for use in paper and woodworking and related fields. The present compositions find particular, but not exclusive, use as adhesive, binder, coating and sealant materials. A large number of the adhesives currently available, particularly for use in woodworking, contain polyvinyl alcohol (PVOH) or a dispersion of another polymer such as polyvinyl acetate in polyvinyl alcohol (PVAc) (PVOH). The adhesives work by forming a physical bond with the wood substrate. In this regard, the -OH groups in the adhesive composition and the -OH groups of the cellulose in the wood substrate together form strong hydrogen bonds. The problems arise with these adhesives because they have poor water resistance. This limits the amount of potential uses for these adhesives. The inherent moisture content of the wood substrate can also cause difficulties for these adhesives. Also, many of the products that are in use in the wood working field require metal salt catalysts in their crosslinking reaction or hardened as aluminum chloride and P1571 / 97MX chromium nitrate, for example. The use of these metal salts has disadvantages in terms of safety both for the manufacture and handling of the adhesive. Also, many of the formulations that are currently available have a low pH value (approximately 3) which can lead to discoloration of tannin-containing wood. British Patent GB 1423558 describes a wood glue that uses a polyisocyanate crosslinker. However, these are highly toxic and unfavorable chemical substances from the environmental point of view. The aziridines have been used as crosslinkers for polymeric compositions for injection molding (GB 1424041) and in adhesives for synthetics containing amines (JP 1026689). The present invention seeks to overcome at least some of the aforementioned problems. With this aim in mind, in one aspect the present invention relates to a two-part package including components A and B, wherein: Component A contains Ai) a solution or dispersion including a polymer containing units with groups hydroxyl; and Aii) a polymer derived from an optionally substituted styrene monomer, this polymer contains P1571 / 97MX units with carboxyl groups; and wherein Component B consists of: Bi) a crosslinker consisting of a polyfunctional aziridine, the crosslinker being capable of carrying out the crosslinking with at least one carboxyl group and at least one hydroxyl group. In this aspect of the invention, it is suitable that components A and B are in liquid form. In the preferred embodiments, the package includes a first compartment that can be opened and that contains the components Ai) and Aii) and a second compartment that can be opened and that contains the component Bi). In another aspect of the present invention there is provided a composition which is obtained by crosslinking Ai) a polymer containing hydroxyl units and Aii) a polymer derived from an optionally substituted styrene monomer, this polymer contains units with carboxyl groups, with Bi) a crosslinker of polyfunctional aziridine which is capable of crosslinking with hydroxyl groups and carboxyl groups. In another aspect the present invention also relates to the use of a composition that is obtained by crosslinking Ai) a polymer containing hydroxyl units and Aii) a polymer derived from an optionally substituted styrene monomer, this polymer contains units P1571 / 97MX with carboxyl groups, with Bi), a polyfunctional aziridine crosslinker as a protective coating, especially for products derived from or containing cellulose, including paper and wood products. Yet another aspect of the present invention relates to the use of a composition that is obtained by crosslinking Ai) a polymer containing hydroxyl units; and Aii) a polymer derived from an optionally substituted styrene monomer, this polymer contains units with carboxyl groups; with Bi) a polyfunctional aziridine crosslinker as an adhesive, especially for wood products and other products derived from or containing cellulose. Other aspects of the present invention relate to methods of providing protective coatings especially for wood and paper products and methods for adhering the surfaces of wood and paper products to other substrates. Preferably, the coating methods include the application of the compositions present in the form of a spray. Suitably, the method for adhering the substrates includes applying the compositions to a substrate using brushes, rollers, etc. In some preferred embodiments, the component Ai) is in the form of an aqueous solution of P1571 / 97MX polyvinyl alcohol. The polyvinyl alcohol can be selected from low and high molecular weight polymers. Polyvinyl alcohols of different degrees of hydrolysis can also be used. The appropriate choice of polyvinyl alcohol will depend on the desired characteristics of the composition, for example the desired viscosity. In other preferred embodiments, component Ai) is an aqueous dispersion of a polymer that includes polyvinyl alcohol as a stabilizer. Preferably, any of these polymers includes units having acetate groups which are popular for use in the woodworking field, but many other types of polymers are suitable. Preferred polymers containing units with acetate groups include homopolymers or copolymers of polyvinyl acetate, most preferably as dispersion with polyvinyl alcohol. Other examples of polymers as component Ai) include the dispersions of copolymers and terpolymers of ethylene vinylacetate. Preferably any component Ai) is miscible in water. It is also preferable that the polymer has a viscosity of between about 20,000 and 80,000 mPas when measured at 23 ° C. Preferably, any of these dispersions has a solids content from about 35% to about 65%. Any of these polymers that P1571 / 97MX include units with acetate groups can be used alone or in combination. Preferably, component Aii) consists of a carboxylated styrene-butadiene rubber latex. It is also preferred that any component Aii) be miscible in water. Preferably, the component has a solids content from about 30% to about 70%. In addition to Ai) and Aii), component A can optionally also include charging materials. Any of these fillers are desirable to improve water resistance. Exemplary fillers include talc, silica, kaolin or calcium carbonate, preferably one or more of these fillers is provided in the form of a fine powder or as a suspension in water. The amount of any of these fillers used may vary according to the desired final properties of the composition. The fillers can prevent excessive penetration of the composition into the substrate. These can also impart better water resistance and film hardness to the final coating / adhesive. The suitable component A includes material (s) of charge in not more than 70% by weight. Preferably, component A includes up to about 50% by weight of filler material, preferably from near P1571 / 97MX from 1% to about 50%, more preferably between 30 and 45%. Component A may also include agents to facilitate storage and management, as they are common in this area. Component A may also include other agents to modify the properties of the crosslinked film product. Optional and additional ingredients / agents include thickening agents (eg, polyacrylic or cellulose thickener such as methylcellulose or hydroxyethylcellulose, aromatic solvents and plasticizers (eg, dibutyl phthalate or butyl benzylphthalate) to improve the flexibility of the final polymeric film. they can employ various weight ratios of components Ai) and Aii) depending on the desired characteristics of the composition. It is preferable that the ratio of Ai) to Aii) be in the range from 1:10 to about 10: 1. More preferably, component A includes approximately equal weight amounts of Ai) and Aii). If the relative amount of Ai) increases beyond this level, this results in a decrease in the water and heat resistance of the subsequent composition. On the other hand, if the level of component Aii) is increased it will result in a reduction in the bonding strength of the subsequent composition. In the different aspects of this P1571 / 97MX invention, the polyfunctional crosslinker is one that is capable of crosslinking a hydroxyl group of the component Ai) and a carboxyl group Aii). The crosslinker Bi) consists of a polyfunctional aziridine crosslinker. It is especially preferred that the aziridine crosslinker be trifunctional and more preferably having the following formula: Mr-? wherein Y is a lower alkyl group from 1 to about 4 carbon atoms. Preferably Y is a methyl group. R is a polymer chain. A particularly preferred polyfunctional aziridine crosslinker in which Y is methyl is commercially available. The crosslinker is designated CAS CAS number 64265-57-2. It is convenient that component B is added in a concentration of not more than about 10% by weight to component A, preferably in a concentration between about 1 to 5% by weight of component A, and most preferably about 3. % by weight of component A. It is highly preferable that the crosslinker be miscible in water. An aqueous dispersion of the crosslinker can be P1571 / 97MX stabilized with the help of solvents such as methyl glycol acetate and glycol solvents. This trifunctional aziridine crosslinker can crosslink the components Ai) and Aii) and the wood substrate as follows: Reaction with the carboxyl group in Aii) CH- - CH - CM, V go CE, C ?. - CU, Reaction with the hydroxyl group in Ai) and the wood substrate ar, - CH - a », > «-cu, -T 30ff R - N 1 J I CH, R and x. CU, - CH - CH, T CR, * "? '? -? - 0 - * ^^ - ^ \ K H H P1571 / 97MX Suitable aziridine crosslinkers are capable of reacting with a carboxyl group at normal room temperature. As a result, the present compositions and the packages are capable of producing an adhesive effect, or of forming a protective coating at room temperature. In the preferred embodiments of the invention, the suitable choice of components Ai), Aii) and B can provide an adhesive or coating composition, for example, which can be employed at room temperature without the need for additional catalysts as required in the formulations of the prior art. The combination of the components A and B according to the present invention give rise to the compositions having better adhesion and water resistance compared to the products currently available. The main and preferred application for the present invention is the woodworking industry, for example the adhesion of wood, the formation of boards with wood particles by binding pieces of wood and wood covering to improve the abrasion resistance, to the chemicals and water. However, the present invention is also applicable to the paper industries, particularly for coating papers to improve water resistance and P1571 / 97MX rigidity. This can be useful in the production of paper cartons. In this sense, another aspect of the present invention relates to a board made with particles that can be obtained by binding wood chips or chips with a composition consisting of the components Ai), Aii) and Bi) as defined in the above. It is desirable that an aziridine crosslinker as component Ai) have a pH between about 10 and 11, especially about 10.5. Typically, component Ai) has a pH of about 4 to 5. Preferably, component Aii) is selected to have a pH of between about 7.5 to 9.5. In this regard, a composition consisting of the components Ai), Aii) and Bi) will usually have a pH higher than the pH-3 value of the prior art compositions. The embodiments of the present invention offer compositions with a pH between about 6.5 to 8.5, especially very close to 7/8. These have the advantage of reducing the possibility of causing discoloration of the tannin-containing wood. Conveniently, components Ai), Aii) and B are selected to provide an adhesive having a hardening time in the container of 1-5 hours, preferably 3-4 hours. As described in the above, the components P1571 / 97MX 1 Ai), Aii) and B are selected so that they are irascible in water. In this way, the present invention also has the advantages of providing a water-borne, cost-effective system that can be free of undesirable solvents such as formaldehyde and phenol. In this regard, the present invention has advantages over the compositions of the prior art. The embodiments of the present invention will now be more described, by way of example, in relation to the examples that accompany it: EXAMPLE A first exemplary formulation was prepared as follows: Component Parts by weight Ai) Dispersion of Acetate Homopolymer 30 p.p.p. of Polyvinyl (PVOH) Solids Content approx. 60%) Aii) Styrene-Butadiene Latex Dispersion 30 p.p. Carboxylated (S.C., approximately 46-52%) Aiii) Loading Material - Long Form of 40 p.p. Paste (Calcium carbonate powder 60-70% in water) A preservative for 0.5"can One package contains two compartments, one where Part A is located and the other contains the Part B.

P1571 / 97MX Part A is a combination of the above-mentioned preferred components Ai) with Aiii). Part B (crosslinker) is preferably an amount of 3 p.p.p. added to the composite dispersion (Part A) before use. In this example B is of Formula I, where Y is methyl. The properties of the first example formulation were determined and compared with those of a commercially available adhesive. The results of the test are shown below.

RESULTS DB THE TEST Example 1 Adhesive available in the Trade Reticulador Aziridina Crystals of metallic polyfunctional salts Binding effect Chemical union Physical union Resistance to water Reasonable Reasonable resistance Reasonable Poor solvents Resistance to Reasonableness Bad abrasion pH Approx. 7-8 - Approx. 3-high long effect little effect of discoloration discoloration Fast Speed - easy Moderation - difficult sedimentation Adjustable mind to adjust Maturity time * Fast - long Slow - long for less than 3 hours at least 6 hours P1571 / 97MX * Maturation refers to the time substrates are allowed to stand at room temperature after pressing to allow them to be suitable for processing such as sawing or sanding.

All proportions in this formulation of Example I may be subject to variation according to the desired final application and cost. However, the formulation that was established in the above has been developed to provide a desirable balance between the final properties such as adhesion, cohesion and hardness of the film. It will be appreciated that the formulation of Example 1 includes equal amounts of components Ai) and Aii). The following Examples 2 and 3 illustrate the effect of varying the weight ratios of the two components in the final properties of the crosslinked product. Components Ai), Aii) and Bi) are the same as those used in the above; only the weight ratios have varied.

P1571 / 97MX EXAMPLE 2 Component Parts by weight Ai) Dispersion (PVOH) of PVAc Homopolymer 54 Aii) XSBR 6 Aiii) Loading material paste 40 B: as in Example 1 EXAMPLE 3 Ai) Dispersion (PVOH) of Homopolymer PVAc 6 Aii) XSBR 54 Aiii) Loading material paste 40 B: as in Example 1 Packs were prepared containing a first container of components Ai) with Aiii) and a second container with only component B. Compared to the formulation of Example I, the formulation of Example 2 exhibited a lower adhesion strength and water resistance and at the lowest heat. Also, compared to the formulation of Example 1, the product of Example 3 was very low in viscosity and thus more difficult to apply to the wood substrate. This also gave rise to various levels of adhesion forces depending on the nature P1571 / 97MX of the wooden substrate. However, they showed good resistance to water and heat. The above examples illustrate the effects of variation in the concentrations of the respective components in the packages and compositions present. Various modifications can be made to the previous Examples.

P1571 / 97MX

Claims (27)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following CLAIMS is claimed as property: 1. A package containing the components A and B, where: component A contains Ai) a solution or dispersion consisting of a polymer containing units with hydroxyl groups, and Aii) a polymer derived from an optionally substituted styrene monomer, the polymer contains units with carboxyl groups; component B consists of Bi) a polyfunctional aziridine crosslinker capable of crosslinking with at least one carboxyl group and at least one hydroxyl group.
2. 2. The package according to claim 1, wherein Ai) is a solution or dispersion of a homopo1imer.
3. 3. The package according to claim 1 or claim 2, wherein Ai) is a solution of polyvinyl alcohol.
4. 4. The package according to claim 1 or claim 2, wherein Ai) is a dispersion that P1571 / 97MX contains polyvinyl alcohol.
5. 5. The package according to the claim 4, wherein Ai) is a dispersion including homopolymer or polyvinyl acetate copolymer.
6. 6. The package according to the claim 5, wherein Ai) is a dispersion that includes the polyvinyl acetate homopolymer.
7. The package according to any of claims 4-6 wherein Ai) includes an ethylene-vinyl acetate copolymer or terpolymer.
8. 8. The package according to any of the preceding claims wherein Aii) consists of a carboxylated styrene-butadiene rubber latex.
9. 9. The package according to any of the preceding claims wherein component A contains Ai) and Aii) in a weight ratio of between 1:10 and 10: 1.
10. 10. The package according to the claim 9, where component A contains Ai) and Aii) in a weight ratio of between 1: 5 and 5: 1.
11. 11. The package according to the claim 10, wherein component A contains Ai) and Aii) in a weight ratio of approximately 1: 1.
12. 12. The package according to any of the preceding claims, wherein component A additionally contains Aiii) one or more materials of P1571 / 97MX loads, and / or AIV) one or more conservatives.
13. The package according to claim 13, wherein component B consists of Bi) a trifunctional aziridine crosslinker of Formula I. CH. - CH-Y H ca-? , \ < * CH, - a-r wherein R is a polymer chain and Y is a lower alkyl group of 1 to 4 carbon atoms.
14. The package according to claim 13, wherein Bi) is a trifunctional aziridine crosslinker in which Y is methyl.
15. 15. The package according to any of the preceding claims, wherein Bi) is miscible in water.
16. 16. The package according to any of the preceding claims, wherein Ai) and Aii) are miscible in water.
17. The package according to any of the preceding claims, wherein the components A and B are provided in a weight ratio of from 100 to 10 to 100 to 0.1.
18. 18. The package according to the claim P1571 / 97HX 17, wherein components A and B are provided in a weight ratio of from 100 to 5 and from 100 to 0.1.
19. 19. The package substantially as described so far in relation to the accompanying Examples.
20. 20. A composition that is obtained by crosslinking the components Ai) and Aii) as defined in any of claims 1 to 11 with a component Bi) as defined in any of claims 13 to 15.
21. 21. The use of a composition according to claim 20 as a protective coating for substrates derived from or containing cellulose.
22. 22. The use of a composition according to claim 20 as adhesive for substrates derived from or containing cellulose.
23. 23. A method for adhering a first cellulosic substrate to a second substrate, which method consists in combining the components A and B as defined in any of claims 1 to 16 to provide an adhesive combination, the application of the combination to the first substrate and contacting the first and second substrates together in the region of the applied adhesive combination.
24. 24. A method to protect a cellulosic substrate, whose method is to combine the P1571 / 97MX components A and B as defined in any of claims 1 to 16 and the application of the combination to the substrate to provide a protective coating.
25. 25. A board formed of particles which is obtained by adhering chips or wood chips together with a composition consisting of a mixture of components A and B as defined in any of claims 1 to 16.
26. 26. A wood product obtainable by adhering the wood substrates with a composition consisting of a mixture of the components A and B as defined in any of claims 1 to 16.
27. 27. The use of a mixture of Ai) a solution or dispersion consisting of in a polymer containing units with hydroxyl groups; Aii) a polymer containing units with carboxyl groups; and Bi) a polyfunctional aziridine crosslinker capable of crosslinking with at least one carboxyl group and at least one hydroxyl group, in a composition for use as an adhesive for substrates derived from or containing cellulose. P1571 / 97MX