JP4592589B2 - Sustained release curing system - Google Patents

Description

  The present invention relates to a curable urea formaldehyde binder composition useful for abrasive cloth paper and engineering wood products. The composition includes a curable urea formaldehyde resin and an aryl phosphite.

  The present invention relates to an abrasive article having a thin layer of abrasive sand or more generally a single layer adhered to a backing. Such products are, for example, abrasive cloth materials and fibrous polishing pads more commonly referred to as “abrasive paper”. Traditionally, thermosetting resins such as glue or phenol formaldehyde resin ("PF resin"), urea formaldehyde resin ("UF resin") have been used in coating formulations. UF resins are less expensive than phenolic resins and have been used to reduce the cost of abrasive products. However, current UF resin systems used in the manufacture of abrasive cloth products are undesirable in working time and curing time under ambient conditions or near ambient conditions. The abrasive paper industry is exploring sustained-release curable urea formaldehyde binder compositions in order to produce a curl-free abrasive paper that has sufficient working time and cures faster and has a sharp image. .

  It is known that phenolic resin compositions are cured at ambient temperature and can be rapidly cured at moderately high temperatures. Gerber's US Pat. No. 5,296,520, etc., can control the working time to solidify the phenolic resin at ambient temperature using an aryl phosphite latent acid catalyst. However, Gerber has found that urea and other amide compounds are highly effective retarders for solidifying this resin at ambient temperatures using aryl phosphite solidifying agents.

  Nevertheless, UF resins differ from phenolic resins, each having a wide variety of chemical properties and manufacturing methods. UF resins are prepared by condensation where urea nitrogen reacts with carbonyl groups of formaldehyde. In contrast, an exemplary phenolic polymer is a phenol formaldehyde resin prepared by aromatic substitution of multiple active sites of phenol, ie, first by formaldehyde and then by reaction with other reactive intermediates. . In the preparation of phenolic resins, catalysts such as strong bases, zinc acetate, borates can be used to produce phenol resoles, and strong acids can be used to produce phenol novolacs. The UF resin can be prepared using a strong acid catalyst such as sulfuric acid. Structurally, phenolic resins are highly aromatic and contain aromatic end groups. In contrast, UF resin is an amino resin and is essentially non-aromatic. With respect to curability, phenolic polymers range from thermoset resoles to thermoplastic novolacs. The UF resin is a thermosetting resin. Therefore, as shown by Gerber (supra), the chemical properties of the UF resin cannot be predicted from the chemical properties of the PF resin.

  The UF precondensate can be mixed with the liquid phenolic resin system. However, such systems are catalyzed by providing a basic environment (pH> 7) as opposed to the acid catalyst used for unmixed urea formaldehyde prepolymers.

  Accordingly, there is a need for a curable urea formaldehyde binder composition using a latent acid solidifying component that provides desirable working and curing times under ambient conditions or near ambient conditions. The results presented below provide a surprising and unexpected improvement in urea formaldehyde binder compositions.

In one embodiment of the invention,
A curable binder composition comprising a urea formaldehyde resin and an aryl phosphite is provided.

In another embodiment of the invention,
A curable binder composition is provided comprising urea formaldehyde resin and an aryl phosphite in an amount of from about 0.05% to about 15% by weight based on the total weight of the resin.

  In accordance with one embodiment of the present invention, curable binder compositions are provided using various concentrations of aryl phosphite. The unique advantages of this curing system include improved tone of urea formaldehyde binder that improves the appearance of final products such as abrasive paper, and faster curing to save energy in the industrial wood products industry. The improvement in color tone is mainly due to the aryl phosphite component. Aryl phosphites act as antioxidants and are known as stabilizers in a wide range of polymers.

  In another embodiment of the present invention, a sustained release curable urea formaldehyde binder composition is provided. It has been discovered that aryl phosphites, such as triphenyl phosphite, act as accelerators in pre-formulated curable binders, but in a sustained release format where the critical parameter is temperature. For example, the cure system is stable at about 70 ° F. (about 21 ° C.), but the cure reaction is accelerated above about 80 ° F. (about 27 ° C.). The working time ranges from about 0.5 hours to over 100 hours. The aryl phosphites of the present invention can be used in a range from about 0.05% by weight based on the total weight of the resin to about 15% by weight based on the total weight of the resin. Urea formaldehyde resins are particularly useful in the present binder composition. Thus, this sustained release curable binder composition is useful for abrasive fabric products and industrial wood applications.

  The terms “hardening” and “curing” are used interchangeably herein.

  The aryl phosphite curing agent of the present invention comprises phosphorous acid having two aromatic organic ester groups and acid hydrogen, three aromatic ester groups, or two aromatic ester groups and one alkyl group. Ester. By way of example, the curing agent may be a disubstituted phosphite such as diphenyl hydrogen phosphite (“DPP”) or a trisubstituted phosphite such as triphenyl phosphite (“TPP”). it can.

The aryl phosphites of the present invention hydrolyze in a controllable manner over a period of time in the presence of water to a stronger acid product, ultimately phosphorous acid. Phosphorous acid, ionization constant pK _a is a strong acid of 1.20. Phosphorous acid is sufficiently acidic to cause the urea formaldehyde resin to solidify at or near ambient temperature.

  The aryl phosphite curing agent of the present invention can be represented by the general formula (I).

式中、Ａｒはアリールであり、Ｘは水素、アリール又はアルキルから選択される。２個のエステル基と水素原子を有する亜リン酸アリール、例えば、亜リン酸水素ジフェニルは、本明細書及び文献において単にエステル基の名称によって呼ばれ、水素が省略されることもある（例えば、亜リン酸ジフェニル（「ＤＰＰ」））。有用な亜リン酸アリール硬化剤としては、亜リン酸水素ジフェニル（ＤＰＰ）；亜リン酸水素ジクレシル（好ましくはメタ又はパラ）；亜リン酸水素フェニルｐ−クレシル；亜リン酸水素フェニルｍ−クレシル；亜リン酸水素ジナフチル；亜リン酸ジフェニルイソプロピル；亜リン酸ジフェニルメチル、亜リン酸ジ（ｐ−クレシル）ヘキシル、亜リン酸トリフェニル（ＴＰＰ）、亜リン酸トリ（ｍ−クレシル）、亜リン酸ジフェニルイソオクチル、亜リン酸ジフェニル２−エチルヘキシル、亜リン酸ジフェニルイソデシル、亜リン酸ジフェニルシクロヘキシル、亜リン酸２−クロロエチルジフェニルなどが挙げられる。１つの有用な市販ＤＰＰ溶液は、Ｄｏｖｅｒ Ｃｈｅｍｉｃａｌ Ｃｏｒｐ．、Ｄｏｖｅｒ、Ｏｈｉｏから入手可能なＤＯＶＥＲＰＨＯＳ ２１３である。１つの有用な市販ＴＰＰ溶液は、Ｄｏｖｅｒ Ｃｈｅｍｉｃａｌ Ｃｏｒｐ．、Ｄｏｖｅｒ、Ｏｈｉｏから入手可能なＤＯＶＥＲＰＨＯＳ １０である。

Wherein Ar is aryl and X is selected from hydrogen, aryl or alkyl. An aryl phosphite having two ester groups and a hydrogen atom, such as diphenyl hydrogen phosphite, is referred to herein simply by the name of the ester group and hydrogen may be omitted (eg, Diphenyl phosphite ("DPP")). Useful aryl phosphite curing agents include diphenyl hydrogen phosphite (DPP); dicresyl hydrogen phosphite (preferably meta or para); phenyl p-cresyl hydrogen phosphite; phenyl m-cresyl hydrogen phosphite. Dinaphthyl hydrogen phosphite; diphenylisopropyl phosphite; diphenylmethyl phosphite, di (p-cresyl) hexyl phosphite, triphenyl phosphite (TPP), tri (m-cresyl phosphite), Examples include diphenylisooctyl phosphate, diphenyl-2-ethylhexyl phosphite, diphenylisodecyl phosphite, diphenylcyclohexyl phosphite, 2-chloroethyldiphenyl phosphite, and the like. One useful commercial DPP solution is Dover Chemical Corp. , DOVERPHOS 213 available from Dover, Ohio. One useful commercially available TPP solution is Dover Chemical Corp. , DOVERPHOS 10, available from Dover, Ohio.

  The working time of the resin can vary widely by varying the total water content, the use of retarders or accelerator additives, the specific phosphite hardener and its amount and temperature. The room temperature or ambient temperature solidified composition of the present invention can have a working time of from about 15 minutes up to about 20 hours. Shore D hardness can be measured using a D-type durometer from New York's Shore Instrument & Manufacturing Company. Another test for ambient temperature solidification is measured using a stick applicator. Here the composition consisting of urea formaldehyde resin, aryl phosphite and water is “stick hard” as described in the Qualitative Flow Procedure defined below within 24 hours of mixing. The ambient temperature solidification composition is preferably a composition comprising diaryl hydrogen phosphite, triaryl phosphite or diaryl phosphite monoalkyl. The triaryl phosphite or diaryl phosphite monoalkyl phosphite can be prehydrolyzed with about 1% to 10% water based on the weight of the aryl phosphite. Phosphites having three organic substituents can be pre-solvated with water, alkanols, glycols and mixtures thereof. The aryl phosphites of the present invention can be formulated with accelerators. However, these pretreatments impair the sustained release aspect of the present invention.

  Aryl phosphite with three organic substituents, such as triaryl phosphite, diaryl monoalkyl phosphite, provides long-term stability at ambient temperature to solidifiable compositions and does not exceed 60 ° C For example, it is preferably used as a latent solidifying agent that rapidly solidifies at a moderately high temperature such as about 35 ° C. to 50 ° C. Thus, such curing agents remain fluid for more than 5 hours at a temperature of about 23 ° C., but can be rapidly cured at higher temperatures depending on the level of aryl phosphite. However, by using low concentrations of diaryl hydrogen phosphite or low concentrations of water, or by using a retarder, diaryl hydrogen phosphite and triaryl phosphite or diaryl phosphite monoalkyl are A stable period can be extended and then solidify rapidly at moderately high temperatures.

  The viscosities of the basic components, ie urea formaldehyde resin, aryl phosphite and water, can be flowable from several hours to over 100 hours at ambient temperature based on the aryl phosphite concentration.

  The amount of aryl phosphite used in the present invention can vary widely. For example, in the curable urea formaldehyde binder of the present invention, the preferred range of aryl phosphite can be in an amount of about 0.05% to about 15% by weight, based on the total weight of the resin. When DPP is used, a more preferred range is from about 0.1% to about 2% by weight based on the total weight of the resin, and a most preferred range is from about 0.30% by weight based on the total weight of the resin. About 2% by weight. When TPP is used, a more preferred range is from about 0.25% to about 5% by weight based on the total weight of the resin.

  The urea formaldehyde resin ("UF resin") of the present invention is an aqueous resin and can be solidified using a solidifying agent or accelerator. For example, useful UF resins have a U: F molar ratio in the range of about 1: 1 to about 1: 3.5. The UF resin of the present invention has a pH range of about 4 to about 9. In the present invention, a formaldehyde scavenger can be used, for example urea that can be back-added to a urea-formaldehyde resin. Modified UF resin can be used in the binder of the present invention.

  The urea-aldehyde resin used in the coatable binder precursor composition useful in the present invention can be made paintable, has the ability to react with each other at high speed in the presence of a catalyst, and is intended Urea or any urea derivative and any aldehyde can be included to provide an abrasive article with acceptable polishing performance for the application. This resin contains a reaction product of aldehyde and urea. Urea-formaldehyde resins are preferred in the polishing industry as described above due to their thermal properties, availability, low cost, and ease of handling. The urea-aldehyde resin is preferably 30 to 95% solids, more preferably 60 to 80% solids, and has a viscosity before addition of water and catalyst of about 125 to about 1500 cps (Brookfield viscometer, # 3 Spindle, 30 rpm, 25 ° C.) and a molecular weight (number average) of at least about 200, preferably about 200 to 700.

  Preferred urea-aldehyde resins for use in the present invention are Borden Chemical, Inc. , Columbus, OH, a resin known as the trade name “AL3029R”. This is an unmodified (ie, free of furfural) urea-formaldehyde resin, 65% solids viscosity (Brookfield, # 3 spindle, 30 rpm, 25 ° C.) 325 cps, free formaldehyde content 0.1 to 0.5 wt% is there.

When the pH of the urea formaldehyde resin is lowered to about 4 or more using an acid that is equal to or higher than phosphorous acid, that is, an acid having _a pK _{a of} 1.20 or less, the solidification rate of the resin using aryl phosphite is higher than when the pK _a has used high acid than that. Examples of acids having _a pK _{a of} 1.2 or less include sulfamic acid, oxalic acid, dichloroacetic acid, trichloroacetic acid, methanesulfonic acid, sulfuric acid, hydrochloric acid, and phenolsulfonic acid. Ammonium chloride can be used as a source of hydrochloric acid and / or buffer components. When the pH is lowered using an acid that is weaker than phosphorous acid such as acetic acid, formic acid, benzoic acid, and salicylic acid, the acidity of the acid is equal to or higher than that of phosphorous acid. It is lower than the reactivity when.

A catalyst may also be used in the curable binder of the present invention. Examples of useful catalysts include, but are not limited to, Lewis acids such as aluminum chloride. A Lewis acid selected from the group consisting of aluminum chloride, iron (III) chloride and copper (II) chloride is preferred. Particularly preferred is Lewis aluminum oxychloride in the form of its non-hydrate (AlCl ₃ ) or hexahydrate (AlCl ₃ .6H ₂ O). Useful catalysts also include organic amine salts or aqueous ammonium ion salts. When ammonium ion salts are used, salts of halide ions such as ammonium ions (NH ₄ ⁺ ), chlorine ions (Cl ⁻ ), fluorine ions (F ⁻ ), bromine ions (Br ⁻ ) are preferable. A particularly preferred ammonium ion salt is ammonium chloride (NH ₄ Cl). Ammonium sulfate ((NH ₄ ) ₂ SO ₄ ), ammonium persulfate ((NH ₄ ) ₂ S ₂ O ₈ ), ammonium thiosulfate ((NH ₄ ) ₂ S ₂ O ₃ ) and ammonium nitrate (NH ₄ NO ₃ ) are cocatalysts As an ammonium ion salt useful when specifically used in combination with AlCl _3, it is considered suitable for use in the present invention. Mixtures of inorganic and organic salts are generally preferably utilized in some cases.

  The solidification reaction of the present invention requires water to hydrolyze the aryl phosphite, for example, ultimately to phosphorous acid. The total water content in the composition, i.e. the water available to hydrolyze the phosphite, is about 0.15 to 5 parts by weight of water, preferably phosphorus phosphite for each part by weight of aryl phosphite. It can vary over a wide range such as about 0.3 to 3 parts by weight of water for each part of the acid ester. The total water content required can be obtained from any of the components in the composition, such as urea formaldehyde resin, or additional water can be added to the composition.

  The composition of the present invention may comprise conventionally used fillers, modifiers and agglomerates together with urea formaldehyde resin. The aggregate material can be a particulate material such as a granule, a powder, or a flake. Suitable aggregate materials include sand, alumina, zirconia, silica, zircon sand, olivine sand, silicon carbide, silicon nitride, boron nitride, bauxite, quartz, chromite, corundum, mixtures thereof, and the like. It is not limited to only. For certain applications, low density aggregate materials such as vermiculite, perlite, pumice are preferred. In other applications, preferred high density aggregates include silica sand, gravel, crushed stone, crushed bricks and the like. Fillers such as mica, kaolin, wollastonite, barite, etc. can be used. The compositions of the present invention can be used to produce abrasive cloth products, such as abrasive paper.

  The coatable binder compositions useful in the present invention include fillers, fibers, lubricants, grinding aids, antistatic agents, wetting agents and surfactants, pigments, dyes, coupling agents, plasticizers, dispersions. Other additives such as agents, suspensions, etc. can be included. The amount of these materials is selected to obtain the desired properties, such as improved wettability of the abrasive. Alternatively, useful binder precursor compositions can be formulated without these additives, and these additives can be added to the binder precursor just prior to application to the base.

  The binder composition of the present invention may contain a formaldehyde scavenger such as urea or an ammonium compound.

  Fillers are frequently used in abrasive articles to reduce costs and improve dimensional stability and other physical properties. The filler can be selected from any filler material that does not adversely affect the hydrodynamic properties of the binder precursor or the polishing performance of the resulting abrasive article. Preferred fillers include calcium metasilicate, aluminum sulfate, aluminum oxide trihydrate, cryolite, magnesia, kaolin, quartz, glass and the like. Fillers that function as grinding aids are cryolite, potassium borofluoride, feldspar and sulfur. Fillers can be used in various amounts, limited only to the premise that the abrasive article retains acceptable mechanical properties (such as flexibility, toughness, etc.).

  The abrasive cloth product of the present invention can be produced by mixing a cured product of the above-described applicable binder precursor composition. The backing can be a polymer film, a paper sheet or a laminate.

  For example, lignocellulosic materials can be used in wood processing applications such as composite boards. Examples of lignocellulosic materials include wood fibers, wood flakes, wood strands, wood chips and wood particles, straw, bagasse, bark, recycled wood fibers, recycled paper fibers, mixtures of these, etc. It is not limited to. The manufactured composite boards are known as fiber boards, wafer boards, strand boards, oriented strand boards, flake boards, particle boards, and the like.

  Several comparative experiments have shown the utility of the present invention. These experiments were designed for polishing and woodworking applications and therefore a cocatalyst was introduced into the binder formulation. The units of the components of curable binders A, B are based on UF resin set to a given mass, then all other components were set to parts per mass of the given UF resin. . Table 1 shows solidification experiments using the curable binders A and B together with viscosity measurements and observation results. The viscosity is read using a Brookfield viscometer, model DV-11 +, # 18 spindle, 20 rpm, and the viscosity unit is centipoise (cps). Total reaction time is calculated from the initial mixing of all components.

Comparative binder A
AL3029R 70
Water 7
25% ammonium chloride 3.64
28% aluminum chloride 0.49
These ingredients were thoroughly mixed at ambient temperature according to the above sequence and then placed in a 15-20 ° C. bath. Five hours after the initial mixing, the viscosity of the reaction mixture was 116.8 cps. After 5 hours and 30 minutes, the mixture was placed in an oven at 32 ° C. After 6 hours and 10 minutes, the viscosity of the reaction mixture was 136.5 cps.

Curable binder A1
AL3029R 70
Water 7
25% ammonium chloride 3.64
28% aluminum chloride 0.49
DOVERPHOS 10 0.84
These ingredients were thoroughly mixed at ambient temperature according to the above sequence and then placed in a 15-20 ° C. bath. Four hours and 55 minutes after the initial mixing, the viscosity of the reaction mixture was 122.7 cps. After 5 hours and 20 minutes, the mixture was placed in an oven at 32 ° C. After 6 hours and 5 minutes, the viscosity of the reaction mixture was 149.4 cps.

Curable binder A2
AL3029R 70
Water 7
25% ammonium chloride 3.64
28% aluminum chloride 0.49
DOVERPHOS 10 1.26
These ingredients were thoroughly mixed at ambient temperature according to the above sequence and then placed in a 15-20 ° C. bath. Four hours and 50 minutes after the initial mixing, the viscosity of the reaction mixture was 128.3 cps. After 5 hours and 10 minutes, the mixture was placed in an oven at 32 ° C. After 6 hours, the viscosity of the reaction mixture was 159.2 cps.

Curable binder A3
AL3029R 70
Water 7
25% ammonium chloride 3.64
28% aluminum chloride 0.49
DOVERPHOS 10 3.5
These ingredients were thoroughly mixed at ambient temperature according to the above sequence and then placed in a 15-20 ° C. bath. Four hours and 50 minutes after the initial mixing, the viscosity of the reaction mixture was 156.3 cps. After 5 hours and 5 minutes, the mixture was placed in an oven at 32 ° C. After 6 hours, the viscosity of the reaction mixture was 208.2 cps.

Curable binder A4
AL3029R 70
Water 7
25% ammonium chloride 3.64
28% aluminum chloride 0.49
DOVERPHOS 213 0.21
These ingredients were thoroughly mixed at ambient temperature according to the above sequence and then placed in a 15-20 ° C. bath. Four hours and 45 minutes after the initial mixing, the viscosity of the reaction mixture was 188.2 cps. After 4 hours and 55 minutes, the mixture was placed in an oven at 32 ° C. After 6 hours, the viscosity of the reaction mixture was 456.5 cps. The viscosity continued to rise at about 3.5 cps / sec.

Comparative binder B
AL3029R 70
Water 7
25% ammonium chloride 3.64
28% aluminum chloride 0.49
These ingredients were thoroughly mixed at ambient temperature according to the above sequence and then placed in a 15-20 ° C. bath. Four hours and 15 minutes after the initial mixing, the viscosity of the reaction mixture was 116 cps. After 4 hours 30 minutes, the mixture was placed in an oven at 32 ° C. After 5 hours and 10 minutes, the viscosity of the reaction mixture was 125.4 cps.

Curable binder B1
AL3029R 70
Water 7
25% ammonium chloride 3.64
28% aluminum chloride 0.49
DOVERPHOS 213 0.07
These ingredients were thoroughly mixed at ambient temperature according to the above sequence and then placed in a 15-20 ° C. bath. Four hours and ten minutes after the initial mixing, the viscosity of the reaction mixture was 121.8 cps. After 4 hours and 20 minutes, the mixture was placed in an oven at 32 ° C. After 5 hours, the viscosity of the reaction mixture was 139.2 cps.

Curable binder B2
AL3029R 70
Water 7
25% ammonium chloride 3.64
28% aluminum chloride 0.49
DOVERPHOS 213 0.14
These ingredients were thoroughly mixed at ambient temperature according to the above sequence and then placed in a 15-20 ° C. bath. 4 hours and 10 minutes after the initial mixing, the viscosity of the reaction mixture was 130.1 cps. The mixture was then placed in a 32 ° C. oven. After 4 hours and 50 minutes, the viscosity of the reaction mixture was 164.3 cps.

Curable binder B3
AL3029R 70
Water 7
25% ammonium chloride 3.64
28% aluminum chloride 0.49
DOVERPHOS 213 0.84
These ingredients were thoroughly mixed at ambient temperature according to the above sequence and then placed in a 15-20 ° C. bath. Two hours and 40 minutes after the initial mixing, the reaction mixture gelled but remained soft.

上記表１に示すように、本発明の結合剤組成物は、例えば、研磨布紙製品を製造するのに有用な徐放性形式で硬化するように加工することができる。異なるレベルの亜リン酸アリールを含む結合剤の硬化特性が比較される。粘度における予想外の改善が、結合剤中の亜リン酸アリールの比較的低レベルで認められた。例えば、０．２から０．３％のＤＰＰレベルでは、粘度はそれぞれ３２％及び３３４％増加した。より高いＤＰＰレベルにおいては、固化はさらにより速くなった。また、１．８及び５．０％のＴＰＰレベルでは、粘度はそれぞれ１７％及び５２％増加した。亜リン酸アリールの有効量と一緒に温度を上昇させても、本発明の結合剤の硬化を加速することができる。

As shown in Table 1 above, the binder composition of the present invention can be processed to cure, for example, in a sustained release format that is useful for producing abrasive cloth products. The curing properties of binders containing different levels of aryl phosphite are compared. An unexpected improvement in viscosity was observed at relatively low levels of aryl phosphite in the binder. For example, at DPP levels from 0.2 to 0.3%, the viscosity increased by 32% and 334%, respectively. At higher DPP levels, solidification was even faster. Also, at TPP levels of 1.8 and 5.0%, the viscosity increased by 17% and 52%, respectively. Increasing the temperature with an effective amount of aryl phosphite can also accelerate the curing of the binder of the present invention.

  A curable urea formaldehyde binder composition comprising an aryl phosphite solidifying agent that acts as a sustained release type accelerator has been disclosed in accordance with the principles of the present invention. Sustained release curable urea formaldehyde binder compositions are useful, for example, in abrasive paper articles. The above examples are representative examples of the present invention, but do not limit the scope of the appended claims. It will be apparent to those skilled in the art that modifications can be made without departing from the spirit of the invention and the scope of the appended claims.

Claims (15)

A curable binder composition comprising a urea formaldehyde resin, an aryl phosphite, and at least one catalyst selected from the group consisting of aluminum chloride, ammonium chloride, and combinations thereof. The curable binder composition of claim 1, wherein the aryl phosphite is present in an amount of 0.05 wt% to 15 wt%, based on the weight of the urea formaldehyde resin. The curable binder composition of claim 1 wherein the urea formaldehyde resin has a urea / formaldehyde ratio of 1: 1 to 1: 3.5. The curable binder composition of claim 1 wherein the urea formaldehyde resin has a pH of 4 to 9. The curable binder composition of claim 2 wherein the urea formaldehyde resin has a pH of 4 to 9. A curable binder composition according to claim 3, wherein the urea formaldehyde resin has a pH of 4 to 9. The curable binder composition of claim 1, wherein the aryl phosphite is selected from the group consisting of diphenyl phosphite and triphenyl phosphite. A urea formaldehyde resin having a urea / formaldehyde ratio of 1: 1 to 1: 3.5,
25% ammonium chloride solution in an amount of 2% to 10% by weight, based on the weight of urea formaldehyde resin,
28% aluminum chloride solution in an amount of 0.1% to 2% by weight, based on the weight of urea formaldehyde resin,
Water in an amount of 5% to 20% by weight based on the weight of the urea formaldehyde resin, and
A curable binder composition comprising an aryl phosphite in an amount of 0.05% to 15% by weight based on the weight of the urea formaldehyde resin. The curable binder composition of claim 8, wherein the aryl phosphite is selected from the group consisting of diphenyl phosphite and triphenyl phosphite. The curable binder of claim 9, wherein the aryl phosphite is diphenyl phosphite and the diphenyl phosphite is present in an amount of 0.1 wt% to 2 wt% based on the weight of the urea formaldehyde resin. Composition . The curable binder composition of claim 10, wherein the diphenyl phosphite is present in an amount of 0.30% to 2% by weight based on the weight of the urea formaldehyde resin. The curability of claim 9 wherein the aryl phosphite is triphenyl phosphite and the triphenyl phosphite is present in an amount of 0.25 wt% to 5 wt% based on the weight of the urea formaldehyde resin. Binder composition . An abrasive cloth product comprising a cured binder obtained by curing the curable binder composition according to claim 1. An abrasive cloth product comprising a cured binder obtained by curing the curable binder composition according to claim 8. A processed wood product comprising a cured binder obtained by curing the curable binder composition according to claim 1.