JP5173250B2 - Method for producing reactive polyurethane beads - Google Patents

Description

  The present invention relates to reactive polyurethane beads and a method for producing the same.

  Polyurethane beads are sometimes used as fillers for paints, plastics, adhesives, cosmetics and the like. For example, when polyurethane beads are used as a filler for paint, the polyurethane beads function as a matting agent, a tactile sensation improver, a design-imparting colorant, etc. it can.

As a method for producing polyurethane beads, an organic phase containing a polyisocyanate compound and a polyol compound is dispersed in a particulate form in an aqueous phase containing water and a dispersant using a stirrer equipped with a cylindrical stirring tank. There are known a method of reacting them (see Patent Literature 1), a method of dispersing polyisocyanate prepolymers in water containing a suspension stabilizer and reacting them (see Patent Literature 2).
According to the method using the stirrer, by adjusting the amount of the dispersing agent, the rotational speed of the cylindrical stirring blade, etc., and in the method using the suspension stabilizer, the type and amount of the suspension stabilizer are adjusted. Thus, the particle diameter of the polyurethane beads can be adjusted. Therefore, according to these methods, polyurethane beads having an appropriate particle size can be produced according to the application.

However, even when conventional polyurethane beads are added as fillers to paints or molding materials, they may fall off due to external forces such as rubbing. Moreover, even when polyurethane beads are added, the intended effect may not be sufficiently exhibited. This is presumably because the conventional polyurethane beads are not chemically bonded to the matrix resin, or the adhesive force at the interface between the matrix resin and the polyurethane beads is insufficient. Therefore, it is conceivable to use polyurethane beads that can be chemically bonded to the matrix resin and can improve the adhesive strength at the interface. For example, Patent Document 3 discloses reactive polyurethane polyurea crosslinked particles having a hydroxyl group.
JP 2004-107476 A Japanese Patent No. 3100787 Japanese Patent No. 3104442

However, since the reactive polyurethane polyurea crosslinked particles described in Patent Document 3 do not react with a resin having an unsaturated bond, when the resin having an unsaturated bond is used as a matrix resin, It was difficult to combine.
An object of this invention is to provide the reactive polyurethane bead which can react with the resin which has an unsaturated bond, and its manufacturing method.

The present invention includes the following configurations.
[1] A step of dispersing a bead raw material containing a vinyl group-containing polyisocyanate prepolymer in water containing a suspension stabilizer and heating it to prepare a polyurethane bead suspension; A method for producing reactive polyurethane beads comprising the steps of solid-liquid separation of a turbid liquid, washing, and drying,
A method for producing reactive polyurethane beads, wherein the vinyl group-containing polyisocyanate prepolymer is obtained by subjecting a trifunctional or higher polyisocyanate prepolymer to an addition reaction of (meth) acrylic acid hydroxy ester.
[2] The method for producing reactive polyurethane beads according to [1], wherein the bead raw material further contains a polyol component.

According to the method for producing reactive polyurethane beads of the present invention, reactive polyurethane beads capable of reacting with a resin having an unsaturated bond can be produced.
When the reactive polyurethane beads of the present invention are added as a filler to a matrix resin having an unsaturated bond, the polyurethane beads and the matrix resin react and become integrated, so that the polyurethane beads are difficult to fall off. Moreover, since the structure of the coating film is stabilized, effects such as scratch resistance, prevention of shrinkage during curing, and stress relaxation can be exhibited.

  In the method for producing reactive polyurethane beads of the present invention, a bead raw material containing a vinyl group-containing polyisocyanate prepolymer is dispersed in the form of particles in water containing a suspension stabilizer, heated, and a polyurethane bead suspension ( Hereinafter, the step of preparing a suspension (hereinafter referred to as suspension polymerization step), and then the step of solid-liquid separation, washing and drying of the suspension (hereinafter referred to as post-treatment step). .)

(Suspension polymerization process)
[Bead raw materials]
The vinyl group-containing polyisocyanate prepolymer contained in the bead raw material is obtained by subjecting a trifunctional or higher polyisocyanate prepolymer to addition reaction of (meth) acrylic acid hydroxy ester.

The polyisocyanate prepolymer referred to in the present invention is a compound obtained by using an isocyanate and having an isocyanate group at the end, or an isocyanate.
The trifunctional or higher polyisocyanate prepolymer is not particularly limited, and examples thereof include isocyanurate type polyisocyanate, adduct type polyisocyanate, and burette type polyisocyanate obtained by trimerizing diisocyanate which is generally used.
The diisocyanate type may be any of yellowing type, non-yellowing type, and non-yellowing type, and is selected according to the intended physical properties. Specific examples include aliphatic diisocyanate compounds and aromatic diisocyanate compounds.
Specific examples of the trifunctional or higher polyisocyanate prepolymer include, for example, isocyanurate type polyisocyanate obtained by trimerizing hexamethylene diisocyanate.

  Further, as a trifunctional or higher polyisocyanate prepolymer, a general trifunctional or higher isocyanate may be used. For example, 1-methylbenzole-2,4,6-triisocyanate, 1,3,5-trimethyl Benzole-2,4,6-triisocyanate, biphenyl-2,4,4′-triisocyanate, diphenylmethane-2,4,4′-triisocyanate, methyldiphenylmethane-4,6,4′-triisocyanate, 4, 4'-dimethyldiphenylmethane-2,2 ', 5,5'-tetraisocyanate, triphenylmethane-4,4', 4 "-triisocyanate, polymeric MDI, and the like.

The (meth) acrylic acid hydroxy ester referred to in the present invention is one or both of acrylic acid hydroxy ester and methacrylic acid hydroxy ester.
Examples of the (meth) acrylic acid hydroxy ester include 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate. Moreover, glycerin di (meth) acrylate etc. can also be used as (meth) acrylic acid hydroxyester.

A catalyst may be added when the (meth) acrylic acid hydroxy ester is added to a trifunctional or higher polyisocyanate prepolymer.
Examples of the catalyst include dibutyltin dilaurate. The amount of the catalyst added is preferably 0.1 to 5000 ppm, more preferably 1 to 1000 ppm, based on the total mass of all components charged during the reaction. If the addition amount of the catalyst is 0.1 ppm or more, the addition reaction can be promoted, and if it is 5000 ppm or less, the polymerization reaction can be easily controlled in the subsequent suspension polymerization, so the particle diameter can be easily adjusted. it can.

  Moreover, in order to prevent cleavage of the vinyl group derived from (meth) acrylic acid hydroxy ester, it is preferable to add a polymerization inhibitor such as dibutyl hydroxytoluene. The addition amount of the polymerization inhibitor is preferably 10 to 10000 ppm, more preferably 50 to 5000 ppm, based on the total mass of all components charged during the reaction. If the addition amount of the polymerization inhibitor is 10 ppm or more, the cleavage of the vinyl group can be sufficiently suppressed, so that the amount of vinyl group in the resulting vinyl group-containing polyisocyanate prepolymer can be sufficiently secured. On the other hand, if the addition amount of the polymerization inhibitor is 10000 ppm or less, inhibition of curing of the curable resin can be prevented when the obtained reactive polyurethane beads are added to the curable resin.

  The ratio of the trifunctional or higher polyisocyanate prepolymer and the (meth) acrylic acid hydroxy ester is preferably such that the hydroxyl equivalent ratio relative to the isocyanate equivalent is 1/1000 to 2/3. If the ratio of hydroxyl group equivalent to isocyanate equivalent is less than 1/1000, the amount of vinyl group introduced tends to decrease, and if it exceeds 2/3, the isocyanate group disappears and does not urethanize. The number of molecules tends to increase.

  The bead raw material may contain a polyisocyanate prepolymer having no vinyl group in addition to the vinyl group-containing polyisocyanate prepolymer. By including a polyisocyanate prepolymer having no vinyl group in the bead raw material, the vinyl group content of the resulting reactive polyurethane beads can be adjusted according to the application, and the reactivity can be adjusted.

Moreover, as a bead raw material, the polyol component below the isocyanate equivalent of the vinyl group containing polyisocyanate prepolymer in a raw material other than a vinyl group containing polyisocyanate prepolymer may be contained suitably.
When the polyol component is contained in the bead raw material, the polyol component is added to the vinyl group-containing polyisocyanate prepolymer, so that the hardness of the resulting reactive polyurethane beads can be adjusted. When the polyol component is small, hard particles can be obtained, and when the polyol component is large, soft particles are easily obtained.
The polyol component may be any of polyester, polyether, acrylic polyol and the like. Moreover, the combination is also possible.

The bead raw material may contain a colorant such as a dye or a pigment. However, the colorant used here does not inhibit the urethanization reaction.
When a colorant is included, colored reactive polyurethane beads can be obtained. If colored reactive polyurethane beads are added to the paint, a coating film having a design property such as a velvet tone or a suede tone can be obtained.
Further, when the viscosity of the suspension is high and it becomes difficult to handle, it is preferable to add a diluent solvent to the bead raw material. The diluent solvent may be any solvent that dissolves the vinyl group-containing polyisocyanate prepolymer and does not inhibit the polymerization reaction.
Further, in order to improve various physical properties of the obtained reactive polyurethane beads, the bead raw material may contain an ultraviolet absorber, an antioxidant, a metal powder, a fragrance, a catalyst and the like.

[Water containing suspension stabilizer]
The bead raw material described above is added to water containing a suspension stabilizer. Water containing the suspension stabilizer is prepared by dissolving or dispersing the suspension stabilizer in water.

The suspension stabilizer is not particularly limited as long as it is generally used in suspension polymerization, and may be organic or inorganic. Specific examples of the suspension stabilizer include cellulose-based water-soluble resins such as methylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose, polyvinyl alcohol, polyacrylates, polyethylene glycol, polyvinylpyrrolidone, polyacrylamide, and tertiary phosphoric acid. Examples include salts. These may be used individually by 1 type and may use 2 or more types together.
A surfactant may be used in combination with the suspension stabilizer. The surfactant used in combination with the suspension stabilizer may be any of an anionic surfactant, a cationic surfactant, a nonionic surfactant, and an amphoteric surfactant.

The addition amount of the suspension stabilizer is preferably 1 to 30 parts by mass with respect to 100 parts by mass of the vinyl group-containing polyisocyanate prepolymer. If the addition amount of the suspension stabilizer is within the above range, the average particle diameter of the reactive polyurethane beads tends to be in the range of 1 to 500 μm suitable as a filler.
When the amount of the suspension stabilizer is more than 30 parts by mass, the average particle size tends to be smaller than 1 μm, and the viscosity of the suspension increases, so that solid-liquid separation and washing tend to be difficult. On the other hand, when the amount of the suspension stabilizer is less than 1 part by mass, the particles tend to aggregate and the particle size tends to be larger than 500 μm.

  The amount of water in which the suspension stabilizer is dissolved or dispersed is preferably 30 to 1000 parts by mass of water with respect to 100 parts by mass of the vinyl group-containing polyisocyanate prepolymer. If the amount of water is 30 parts by mass or more, the bead raw material can be stably dispersed, and if it is 1000 parts by mass or less, a sufficient production amount of reactive polyurethane beads per one suspension polymerization is ensured. can do.

[Suspension polymerization conditions]
In order to disperse the bead raw material into water after adding it to water containing a suspension stabilizer, a stirring method is usually employed. The stirring speed at that time is preferably adjusted as appropriate so that the vinyl group-containing polyisocyanate prepolymer dispersed particles have a predetermined particle diameter.
After the adjustment of the particle size of the vinyl group-containing polyisocyanate prepolymer dispersed particles is completed, the suspension is heated to a temperature of 30 to 90 ° C. and subjected to suspension polymerization for 1 to 6 hours to obtain a suspension.
When the bead raw material does not contain a polyol component, the vinyl group-containing polyisocyanate prepolymer dispersed particles react with water in the suspension polymerization to form polyurethane beads.
When the polyol component is contained in the bead raw material, the polyisocyanate prepolymer dispersed particles containing vinyl group react with water and the polyol component in the suspension polymerization to form polyurethane beads.

(Post-processing process)
In the solid-liquid separation in the post-processing step, for example, filtration or centrifugation is applied.
In washing, the reactive polyurethane beads separated and recovered are further washed with water or the like to remove the suspension stabilizer remaining on the polyurethane beads.
In the drying, for example, a heat drying method, an airflow drying method, a vacuum drying method, an infrared drying method, or the like is applied. For example, when the heat drying method is applied, the drying temperature is preferably 40 to 110 ° C., and the drying time is preferably 2 to 40 hours.

  When the suspension is solid-liquid separated and washed, the suspension may be treated with an enzyme such as cellulose-degrading enzyme that decomposes the suspension stabilizer, polyvinyl alcohol-degrading enzyme, or a reagent such as hypochlorite. Good. By treating with the reagent, the viscosity of the suspension can be lowered to facilitate the solid-liquid separation operation, and the washing can be easily performed.

(Polyurethane beads)
According to the method for producing polyurethane beads of the present invention, reactive polyurethane beads comprising a reactive polyurethane having a (meth) acryloxy group can be obtained.
The average particle diameter of the reactive polyurethane beads is appropriately selected depending on the purpose of use, but is preferably 1 to 500 μm suitable as a filler.
The average particle diameter of the reactive polyurethane beads can be easily adjusted by adjusting the amount of the suspension stabilizer. Specifically, the average particle size decreases as the amount of the suspension stabilizer increases, and the average particle size increases as the amount decreases.
The iodine value of the reactive polyurethane beads is preferably 0.2 or more. If the iodine value is 0.2 or more, it can be sufficiently bonded to the matrix resin.

 Since the reactive polyurethane beads of the present invention have a (meth) acryloxy group, they can react with a resin having an unsaturated bond. When the reactive polyurethane beads of the present invention react with the resin having an unsaturated bond, the polyurethane beads and the resin are firmly bonded. Therefore, it is possible to prevent the polyurethane beads from falling off. In addition, since the structure of the resin and bead interface is stabilized, scratch resistance, shrinkage prevention during curing, crack suppression by stress relaxation, and prevention of breakage can be achieved.

  The reactive polyurethane bead of the present invention is added as a filler to, for example, a coating composition, a molding material composition, a sealing agent composition, etc. made of an energy ray curable resin, and has a performance as a coating material, a molding material, or a sealing agent. Can be improved.

<Synthesis Example 1>
In a 2 L autoclave thoroughly substituted with nitrogen gas and dried, 1000 g of hexamethylene diisocyanate isocyanurate type polyisocyanate (isocyanate group content 22.0 mass%), 227 g of 2-hydroxypropyl acrylate, 0.012 g of dibutyltin dilaurate , 0.614 g of dibutylhydroxytoluene was charged. Further, after the inside of the autoclave was sufficiently substituted with nitrogen gas, it was sealed and reacted by stirring and mixing at 600 ° C. for 12 hours. Thereafter, toluene was added to obtain a compound (I) which was a toluene solution containing a vinyl group-containing polyisocyanate prepolymer and having a nonvolatile content of 80% by mass. The compound (I) had an isocyanate content of 9.6% by mass and a viscosity of 430 mPa · s (25 ° C.).

<Synthesis Example 2>
In a 2 L autoclave thoroughly substituted with nitrogen gas and dried, 1000 g of hexamethylene diisocyanate isocyanurate type polyisocyanate (isocyanate group content 22.0 mass%), 251 g of 2-hydroxypropyl methacrylate, 0.012 g of dibutyltin dilaurate , 0.614 g of dibutylhydroxytoluene was charged. Further, the inside of the autoclave was sufficiently replaced with nitrogen gas, and then sealed, and the reaction was carried out by stirring and mixing at 60 ° C. for 12 hours. Thereafter, toluene was added to obtain a compound (II) which was a toluene solution containing a vinyl group-containing polyisocyanate prepolymer and having a nonvolatile content of 80% by mass. The composite (II) had an isocyanate content of 9.4% by mass and a viscosity of 420 mPa · s (25 ° C.).

<Example 1>
800 g of water was charged into a separable flask equipped with a 2 L stirrer, and 32 g of Metrose 90SH-100 (hydroxypropylmethylcellulose, manufactured by Shin-Etsu Chemical Co., Ltd.) was dissolved therein to prepare a dispersion medium. While stirring the dispersion medium at 600 rpm, a mixture of 475 g of the compound (I) and 20 g of PTMG1000 (polytetramethylene glycol, hydroxyl value 112 mgKOH / g, manufactured by Mitsubishi Chemical Corporation) as a polyol was added to prepare a suspension. . Next, the suspension was heated to 60 ° C. with continued stirring, reacted for 4 hours, and then cooled to room temperature to obtain a suspension. This suspension was subjected to solid-liquid separation, sufficiently washed with water, and then dried at 70 ° C. for 20 hours to obtain polyurethane beads having an average particle diameter of 10 μm.
When the infrared absorption spectrum of this polyurethane bead was measured, an absorption peak near 812 cm ⁻¹ derived from a vinyl group was shown. The iodine value was measured to be 14.4.

<Example 2>
Polyurethane beads having an average particle diameter of 10 μm were obtained in the same manner as in Example 1 except that the composite (II) was used instead of the composite (I).
When the infrared absorption spectrum of this polyurethane bead was measured, an absorption peak near 812 cm ⁻¹ derived from a vinyl group was shown. Moreover, it was 14.2 when the iodine value was measured.

<Example 3>
Polyurethane beads having an average particle diameter of 20 μm were obtained in the same manner as in Example 1 except that the amount of Metroze 90SH-100 was 24 g.
When the infrared absorption spectrum of this polyurethane bead was measured, an absorption peak near 812 cm ⁻¹ derived from a vinyl group was shown. Moreover, it was 14.0 when the iodine number was measured.

<Example 4>
A separable flask equipped with a 2 L stirrer was charged with 800 g of water, and 32 g of Metrose 90SH-100 was dissolved therein to prepare a dispersion medium. While stirring the dispersion medium at 600 rpm, 250 g of the composite (I), 20 g of PTMG1000 as a polyol, and isocyanurate type polyisocyanate of hexamethylene diisocyanate as a polyisocyanate prepolymer having no vinyl group (isocyanate group content 22. A suspension was prepared by adding 180 g of 0% by mass) and 45 g of toluene as a diluent solvent. The suspension was heated to 60 ° C. with continued stirring, reacted for 4 hours, and then cooled to room temperature to obtain a suspension. This suspension was subjected to solid-liquid separation, sufficiently washed with water, and then dried at 70 ° C. for 20 hours to obtain polyurethane beads having an average particle diameter of 10 μm.
When the infrared absorption spectrum of this polyurethane bead was measured, an absorption peak near 812 cm ⁻¹ derived from a vinyl group was shown. Moreover, it was 7.6 when the iodine number was measured.

<Example 5>
A separable flask equipped with a 2 L stirrer was charged with 800 g of water, and 32 g of Metrose 90SH-100 was dissolved therein to prepare a dispersion medium. While stirring the dispersion medium at 600 rpm, 300 g of the composite (I), Plaxel 312 (trimethylolpropane / caprolactone adduct, hydroxyl value 135 mgKOH / g, manufactured by Daicel Chemical Industries, Ltd.) as a polyol component, and a diluent solvent A mixture of 40 g of toluene was added to prepare a suspension. The suspension was heated to 60 ° C. with continuous stirring, reacted for 4 hours, and then cooled to room temperature to obtain a suspension. This suspension was subjected to solid-liquid separation, sufficiently washed with water, and then dried at 70 ° C. for 20 hours to obtain polyurethane beads having an average particle diameter of 10 μm.
When the infrared absorption spectrum of this polyurethane bead was measured, an absorption peak near 812 cm ⁻¹ derived from a vinyl group was shown. Moreover, it was 9.1 when the iodine value was measured.
Moreover, the polyurethane beads of Example 5 using Plaxel 312 as a polyol component had a softer feel than those obtained in Examples 1 to 4.

<Example 6>
A separable flask equipped with a 2 L stirrer was charged with 800 g of water, and 32 g of Metrose 90SH-100 was dissolved therein to prepare a dispersion medium. While stirring the dispersion medium at 600 rpm, 425 g of the composite (I), 20 g of PTMG1000 as a polyol component, 40 g of Resino Black UD403 (manufactured by Resino Color Industries Co., Ltd.) as a black pigment, and 30 g of toluene as a diluting solvent are added. A suspension was prepared. The suspension was heated to 60 ° C. with continued stirring, reacted for 4 hours, and then cooled to room temperature to obtain a suspension. This suspension was subjected to solid-liquid separation, sufficiently washed with water, and then dried at 70 ° C. for 20 hours to obtain black polyurethane beads having an average particle diameter of 10 μm.
When the infrared absorption spectrum of this polyurethane bead was measured, an absorption peak near 812 cm ⁻¹ derived from a vinyl group was shown. Moreover, it was 12.9 when the iodine number was measured.

  The polyurethane beads obtained by the production methods of Examples 1 to 6 were found to have a vinyl group from the measurement of infrared absorption spectrum and iodine value. Such polyurethane beads can react with a resin having an unsaturated bond.

Claims (2)

Dispersing the bead raw material containing the vinyl group-containing polyisocyanate prepolymer into water containing a suspension stabilizer in the form of particles and heating to prepare a polyurethane bead suspension; and A process for producing reactive polyurethane beads comprising steps of solid-liquid separation, washing and drying,
A method for producing reactive polyurethane beads, wherein the vinyl group-containing polyisocyanate prepolymer is obtained by subjecting a trifunctional or higher polyisocyanate prepolymer to an addition reaction of (meth) acrylic acid hydroxy ester.   The method for producing reactive polyurethane beads according to claim 1, wherein the bead raw material further contains a polyol component.