JP4529437B2 - Powdered polyurethane resin for slush molding, manufacturing method thereof and slush molding method - Google Patents

Description

  The present invention relates to a powder polyurethane resin for slush molding, a method for producing the same, and a slush molding method. More specifically, the present invention relates to a powder polyurethane resin for slush molding having good mechanical strength and easy disposal, and a method for producing the same and a slush molding method.

  The slush molding method is easy to form products with complicated shapes (undercut, deep drawing, etc.), can be made uniform in thickness, and has a good material yield rate, so it is widely used for automotive interior materials. In general, soft polyvinyl chloride (hereinafter referred to as PVC) powder is used for such applications (see Patent Document 1). However, since softened PVC contains a large amount of a low molecular weight plasticizer, there is a problem that the soft feeling disappears below the freezing point of the plasticizer. In addition, when used for a long period of time, an oil film is formed (fogging) on the windshield of the vehicle due to the volatilization of the plasticizer, the matte effect or softness disappears due to the migration of the plasticizer to the molding surface, and PVC There was a problem of yellowing due to deterioration over time. Further, PVC contains a large amount of halogen atoms, and thus has a problem of toxic gas at the time of combustion and a disadvantage of poor recyclability.

JP-A-5-279485

  In recent years, a thermoplastic polyurethane resin (hereinafter abbreviated as TPU) having good physical properties such as moldability and scratch resistance has been proposed as a soft material for powder slush molding that replaces PVC. Patent Document 2 discloses a powder TPU using a specific polycarbonate diol.

Japanese Patent Laid-Open No. 2001-261772

  However, although the polycarbonate diol TPU of Patent Document 2 is excellent in strength, flexibility, weather resistance, heat resistance, low temperature characteristics, hydrolysis resistance, molding processability, etc., it has difficulty in adhesion to the substrate. Also, there is a problem in terms of disposal.

  The molded product made of the powdered polyurethane resin for slush molding obtained by the present invention is excellent in mechanical strength and biodegradability. The molded product made of the slush molded powder polyurethane resin obtained by the present invention is particularly suitable as an interior material for automobiles, and is also useful as a material for indoor furniture such as a sofa.

  The present invention has been made to solve the above-mentioned problems, and provides a powder polyurethane resin for slush molding having good mechanical strength and easy disposal, and a method for producing the same and a slush molding method. With the goal.

  That is, this invention is shown by the following (1)-(5).

(1) For slush molding obtained by reacting a polymer polyol (A) having a number average molecular weight of 500 to 10,000, a chain extender (B) having a number average molecular weight of less than 500, and an organic polyisocyanate (C). In the powder polyurethane resin, the polymer polyol (A) contains a lactic acid-based polyester diol (A1) obtained by polycondensation of lactic acid with a diol having a number average molecular weight of 62 to 5,000. Powder material made of polyurethane resin .

(2) The powder material comprising the polyurethane resin for slush molding according to claim 1, wherein the lactic acid polyester diol (A1) has a number average molecular weight of 500 to 10,000.

(3) In the presence of the dispersant (D), the polymer polyol (A) is dispersed in the dispersion medium (E) and then reacted with the organic polyisocyanate (C) to obtain an isocyanate group-terminated urethane prepolymer dispersion. After that, the method for producing a powder material comprising the polyurethane resin for slush molding according to (1) or (2), wherein the chain extension reaction is performed by adding the chain extender (B) to the dispersion.

(4) The slush molding characterized in that the powder polyurethane resin composition for slush molding of (1) or (2) is put into a heated mold and then melt-molded after removing excess resin. Method.

First, the raw materials used in the present invention will be described.
The polymer polyol (A) used in the present invention has a number average molecular weight of 500 to 10,000 (preferably 1,000 to 5,000) and contains a lactic acid polyester diol (A1). And When the number average molecular weight of the polymer polyol (A) is less than the lower limit, the melting temperature of the obtained powder TPU becomes too high, and the molding process becomes difficult. When the upper limit is exceeded, the physical properties of the molded product become insufficient.

  The lactic acid polyester diol (A1) is obtained by polycondensation of lactic acid to a diol having a number average molecular weight of 62 to 5,000 (preferably 62 to 500). The number average molecular weight of the lactic acid polyester diol (A1) is preferably 500 to 10,000, and particularly preferably 1,000 to 5,000. When the number average molecular weight of (A1) is less than the lower limit, the biodegradability in the obtained powder TPU is lowered. If the upper limit is exceeded, the physical properties of the slush molded product will deteriorate.

  The diol having a number average molecular weight of 62 to 5,000 (preferably 62 to 3,000) in the lactic acid polyester diol (A1) is a low molecular diol having a number average molecular weight of 62 to 500 and a number average molecular weight of more than 500 to 5,000. There are oligomeric diols. In this invention, these are used individually or in mixture of 2 or more types.

  Low molecular diols include ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol. 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, 3,3-dimethylolheptane, diethylene glycol, 1,4 -Cyclohexanediol, 1,4-cyclohexanedimethanol, 2-ethyl-1,3-propanediol, 2-normalpropyl-1,3-propanediol, 2-isopropyl-1,3-propanediol, 2-normalbutyl -1,3-propanediol, 2-isobutyl-1,3-propa Diol, 2-tertiarybutyl-1,3-propanediol, 2-methyl-2-ethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-ethyl-2-normal Propyl-1,3-propanediol, 2-ethyl-2-normalbutyl-1,3-propanediol, 2-ethyl-3-ethyl-1,4-butanediol, 2-methyl-3-ethyl-1, 4-butanediol, 2,3-diethyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 2,3,4-triethyl-1,5-pentanediol, trimethylolpropane, Alkyleneoxy of dimethylolpropionic acid, dimethylolbutanoic acid, dimer acid diol, glycerin, pentaerythritol, bisphenol A Id adducts.

  The oligomer diol is obtained by polycondensing the low molecular weight diol with a dicarboxylic acid such as succinic acid, adipic acid, sebacic acid, azelaic acid, terephthalic acid, isophthalic acid, orthophthalic acid, hexahydroterephthalic acid, hexahydroisophthalic acid or the like. Polyester diol obtained by ring-opening addition polymerization of a cyclic ester such as ε-caprolactone to the low-molecular diol, and ring-opening addition polymerization of alkylene oxide such as ethylene oxide or propylene oxide to the low-molecular diol. Polyether diols obtained by transesterification with low-molecular carbonates such as diethyl carbonate, diphenyl carbonate, ethylene carbonate, etc. That.

  Lactic acid is a mixture of two types of optical isomers, D-lactic acid and L-lactic acid, and any mixing ratio can be used.

  In the present invention, the polymer polyol (A) other than the above (A1) can be a polymer polyol usually used in the urethane industry. For example, a polyester polyol other than (A1), a polyesteramide polyol, a polyether polyol, Examples include polyether / ester polyols, polycarbonate polyols, and polyolefin polyols. These are used alone or in combination.

  Examples of the chain extender include low molecular polyols having a number average molecular weight of less than 500, low molecular weight polyamines such as ethylenediamine, hexamethylenediamine, xylylenediamine, isophoronediamine, and ethylenetriamine, monoethanolamine, diethanolamine, and monopropanolamine. Water, such as a low molecular amino alcohol, is mentioned, These are used individually or in combination.

  Examples of the organic polyisocyanate used in the present invention include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylene-1,4-diisocyanate, xylene-1,3-diisocyanate, tetramethylxylene diisocyanate, 4, 4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate, 2,2'-diphenylpropane-4,4'-diisocyanate, 3 , 3'-dimethyldiphenylmethane-4,4'-diisocyanate, 4,4'-diphenylpropane diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, naphthylene-1,4-di Aromatic diisocyanates such as socyanate, naphthylene-1,5-diisocyanate, 3,3′-dimethoxydiphenyl-4,4′-diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (hereinafter abbreviated as HDI), decamethylene diisocyanate, lysine Aliphatic diisocyanates such as diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tetramethylxylene diisocyanate, and other polymers, polymers, and polymers, urethanes Modified body, allophanate modified body, urea modified body, biuret modified body, carbodiimide modified body, uretonimine modified body Uretdione modified product, an isocyanurate modified product, and further mixtures of two or more thereof. In the present invention, in consideration of the weather resistance of the molded product, aliphatic and / or alicyclic diisocyanates are preferable, and HDI is particularly preferable.

  In the present invention, a reaction terminator can be used as necessary. Examples of the reaction terminator include low molecular amino alcohols having a molecular weight of less than 500 (number average), low molecular monools such as methanol and ethanol, and primary or secondary monoamines such as ethylamine and diethylamine. These may be used alone or in combination.

  The method for producing a powdered polyurethane resin for slush molding of the present invention is a method of pulverizing an already produced resin, a method of precipitating a resin from a resin solution, an aqueous emulsion, and coagulating the emulsion to produce a resin powder. And a method using non-aqueous dispersion polymerization. In the present invention, a non-aqueous dispersion polymerization method in which a particle size distribution is small and a spherical shape is obtained is preferable.

  The non-aqueous dispersion polymerization method, which is a preferred method for producing the slush molding powder polyurethane resin of the present invention, will be described in detail.

  Examples of the method for producing the powder polyurethane resin for slush molding include a prepolymer method and a one-shot method. In the present invention, the prepolymer method is preferred.

  A method for producing a powder polyurethane resin for slush molding by the non-aqueous dispersion prepolymer method will be described in detail.

  A method for producing a powder polyurethane resin for slush molding by a non-aqueous dispersion prepolymer method is as follows. In the presence of a dispersant (D), a polymer polyol (A) is dispersed in a dispersion medium (E), and then an organic polyisocyanate (C ) To obtain an isocyanate group-terminated urethane prepolymer dispersion, and then a chain extender (B) is added to the dispersion to conduct a chain extension reaction.

  The first step is a step of uniformly dispersing the polymer polyol (A) in the dispersion medium (E) that does not substantially dissolve the polyurethane resin.

  The dispersion medium (E) is a fat such as pentane, hexane, heptane, octane, dodecane, paraffinic solvent, etc., when the polymer polyol (A) is mainly composed of polyester, polyether, etc. Nonpolar and / or low polarity organic media such as organic organic media, alicyclic organic media such as cyclopentane, cyclohexane, methylcyclohexane, etc., organic media used as plasticizers such as dioctyl phthalate, etc. In the case where a non-polar material such as a hydroxyl group-containing polybutadiene or a hydroxyl group-containing hydrogenated polybutadiene is a main component, a polar organic medium such as acetone or methyl ethyl ketone can be used.

  Moreover, the average particle diameter of the powder polyurethane resin for slush molding to be generated can be adjusted by using a nonpolar and / or low polarity dispersion medium in combination with a polar dispersion medium.

  The mass ratio of the total amount of the disperse phase composed of raw materials other than the disperse medium and the continuous phase composed of the disperse medium is a range in which the disperse phase / continuous phase = 10/90 to 80/20 in consideration of production efficiency and production cost. Is preferable, and 40/60 to 80/20 is more preferable.

  In addition, when dispersing a polymer polyol uniformly in a dispersion medium, the dispersing agent (D) shown below is used.

  Dispersants (D) include those containing an active hydrogen group in the molecule (D1) and those not containing (D2). The dispersant (D) subdivides the polymer polyol (A) as a constituent component of the powder polyurethane resin for slush molding in the present invention and uniformly disperses it in the dispersion medium (E). A portion having a high affinity and a portion having a high affinity for the dispersion medium (E) are present in one molecule.

  The dispersant (D1) containing an active hydrogen group is a reaction product of an organic oligomer containing an active hydrogen group and having an unsaturated bond, and an ethylenically unsaturated monomer having a side chain of 6 or more carbon atoms. Is preferred.

  The dispersant (D2) containing no active hydrogen group includes (1) an organic oligomer having no active hydrogen group and having an unsaturated bond, and an ethylenically unsaturated monomer having a side chain of 6 or more carbon atoms. Reaction products (2) Reaction products obtained by reacting active hydrogen groups of the active hydrogen group-containing dispersants with active hydrogen group masking agents such as monoisocyanates such as phenyl isocyanate and monocarboxylic acids are preferred. .

  Examples of the organic oligomer having an unsaturated bond and containing an active hydrogen group include, for example, a polyester polyol produced by using an unsaturated bond-containing glycol or an unsaturated bond-containing dicarboxylic acid as a part of glycols and dibasic acids, Polyether polyol produced using a bond-containing glycol as a starting material, a polyol obtained by esterification reaction of a hydroxyl-terminated polyester, polyether, polycarbonate, etc. having a number average molecular weight of 2,000 or less and an unsaturated bond-containing dicarboxylic acid In addition, polyolefin polyol and the like can be mentioned. Examples of the unsaturated bond-containing glycol include 2-butene-1,4-diol, glycerin monoallyl ether, and the like. Examples of the unsaturated bond-containing dicarboxylic acid include maleic acid and itaconic acid.

  Examples of the organic oligomer that does not contain an active hydrogen group and has an unsaturated bond include, for example, the above-described polyester polyol raw material polyol and monool OH component, and the above-mentioned polyester polyol raw material dibasic acid, maleic acid, and fumaric acid. Dehydration reaction products of polyesters composed of COOH components using unsaturated bond-containing dicarboxylic acids such as acid and itaconic acid, polyether monools and unsaturated bond-containing dicarboxylic acids, and the weight of diene monomers such as polybutadiene and polyisoprene. Examples include coalescence.

  These organic oligomers preferably have a number average molecular weight of 500 to 10,000, particularly 500 to 9,000. The unsaturated bond concentration is preferably 10 mol or less per molecule of the organic oligomer.

  Examples of the ethylenically unsaturated monomer having a side chain having 6 or more carbon atoms include 1-octene, 1- or 2-nonene, 1- or 2-decene, 1- or 2-heptadecene, 2-methyl- 1-nonene, 2-methyl-1-decene, 2-methyl-1-dodecene, 2-methyl-1-hexadecene, 2-methyl-1-heptadecene, etc. vinyl, propenyl or isopropenyl group-containing aliphatic linear type Esters of unsaturated hydrocarbons, acrylic acid or methacrylic acid and aliphatic alcohols having 6 or more carbon atoms such as 2-ethylhexyl alcohol or hexyl alcohol, or alicyclic alcohols having 6 or more carbon atoms such as cyclohexanol, norbonal or adamantanol In addition, a reaction product of acrylic acid and polycaprolactone diol, such as Plaxel (registered trader) manufactured by Daicel Chemical Industries, Ltd. ) FA-4, and the like.

  There are no particular restrictions on the reaction between the unsaturated bond-containing organic oligomer and the ethylenically unsaturated monomer, but generally known reaction initiators in radical polymerization reactions such as benzoyl peroxide and azobisisobutyronitrile Solvents such as ethyl acetate and cyclohexane can be used.

  Furthermore, the ratio of the organic oligomer having an unsaturated bond and the ethylenically unsaturated monomer having 6 or more carbon atoms is preferably organic oligomer / ethylenically unsaturated monomer = 100/20 to 100/400 (mass ratio). . When the ratio of the ethylenically unsaturated monomer to 100 parts by mass of the organic oligomer is too small, sufficient performance as a dispersant cannot be obtained. On the other hand, when the amount is too large, the balance of the raw material dispersion in the reaction system is lost during the non-aqueous dispersion polymerization, and the effect as a dispersant cannot be sufficiently exhibited.

  When the polymer polyol (A) is dispersed in the dispersion medium (E), the organic polyisocyanate (B) is charged into the dispersion and reacted to obtain an isocyanate group-terminated urethane prepolymer dispersion.

  The reaction temperature in the prepolymerization reaction (urethanization reaction) is 60 to 140 ° C., and the reaction time is about 1 to 10 hours. Further, a catalyst can be used as necessary. As the catalyst, ordinary urethanization catalysts, allophanatization catalysts and the like are used, and examples thereof include triethylenediamine, bis-2-dimethylaminoethyl ether, dibutyltin dilaurate, lead naphthenate, iron naphthenate, copper octenoate and the like. be able to.

  In the prepolymerization reaction, the molar ratio at the time of charging the isocyanate group and the hydroxyl group is preferably isocyanate group / hydroxyl group = 1.05 / 1 to 5/1, particularly preferably isocyanate group / hydroxyl group = 1.1 to 2.0. preferable.

  Thereafter, a chain extender and / or a reaction terminator is charged and reacted. (Third step) At this time, a chain extender and / or a reaction terminator, which becomes the same or excessive amount of active hydrogen groups, is charged from the amount of isocyanate groups in the prepolymer, and reacted until the isocyanate groups disappear. The reaction temperature at this time is preferably 40 to 100 ° C.

  When the chain extension reaction is completed, it is a step of taking out the powder polyurethane resin composition for slush molding from the dispersion. The specific operation is an operation of recovering the powdered polyurethane resin composition from the dispersion by filtration or decantation after the reaction, and then drying at normal temperature or reduced pressure and at normal temperature or by heating.

  The shape of the powdered polyurethane resin for slush molding thus obtained is preferably spherical when considering the fluidity (flowability during molding) of the powder resin composition. Moreover, the angle of repose of the powder polyurethane resin composition of the present invention is preferably 50 ° or less, more preferably 10 ° to 40 °. When the angle of repose exceeds the upper limit, the flowability at the time of molding is deteriorated, and molding defects are likely to occur.

  The number average molecular weight of the obtained powder polyurethane resin for slush molding is preferably 5,000 to 100,000, particularly preferably 10,000 to 50,000. If the number average molecular weight is too small, the mechanical strength and durability of the molded product tends to be insufficient. If the number average molecular weight is too large, moldability tends to be insufficient.

  The average particle diameter of the obtained powder polyurethane resin for slush molding is 1,000 μm or less, preferably 10 to 500 μm, particularly preferably 100 to 200 μm. When the average particle size is large, pinholes are likely to occur at undercuts and corners. On the other hand, if it is small, the flowability and powder breakage deteriorate, and the thickness of the molded product tends to be uneven. The “average particle size” is a value of a cumulative percentage of 50% in a particle size distribution curve measured with a laser particle size analyzer.

  This powder polyurethane resin for slush molding contains additives as necessary, such as pigments / dyes, antioxidants, ultraviolet absorbers, antiblocking agents, radical polymerization initiators, coupling agents, flame retardants, inorganic and organic fillers. Further, a lubricant, an antistatic agent, a cross-linking agent and the like can be added.

  In particular, organic pigments include insoluble azo pigments, soluble azo pigments, copper phthalocyanine pigments, quinacridone pigments, etc., and inorganic pigments include chromates, ferrocyan compounds, metal oxides, metal salts (sulfates) Silicate, carbonate, phosphate, etc.), metal powder, carbon black and the like. The addition amount of the pigment is usually 0 to 5% by mass, preferably 1 to 3% by mass with respect to the powder polyurethane resin composition.

  Antioxidants include phenol-based [2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, etc.], bisphenol-based [2,2′-methylenebis (4-methyl-6-tert-butylphenol) Etc.], phosphorus [triphenyl phosphite, diphenylisodecyl phosphite, etc.] and combinations of two or more of these. Further, examples of the ultraviolet absorber include benzophenone [2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, etc.], benzotriazole [2- (2′-hydroxy-5′-methylphenyl) benzotriazole, etc. ], Salicylic acid type [phenyl salicylate and the like], hindered amine type [bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate and the like] and combinations of two or more of these. The addition amount of the antioxidant and the ultraviolet absorber is usually 0 to 5% by mass, preferably 0.01 to 3% by mass with respect to the powder polyurethane resin composition.

  There are no particular limitations on the anti-blocking agent, and there are known inorganic anti-blocking agents or organic anti-blocking agents. Examples of inorganic anti-blocking agents include silica, talc, titanium oxide, calcium carbonate, and organic blocking. As the inhibitor, a thermosetting resin having a particle size of 10 μm or less (for example, a thermosetting polyurethane resin, a guanamine-based resin, or an epoxy resin) and a thermoplastic resin having a particle size of 10 μm or less (for example, a thermoplastic polyurethane urea resin, poly (Meth) acrylate resin). Among these, preferred are inorganic antiblocking agents, and particularly preferred is silica. The addition amount of the anti-blocking agent is usually 0 to 3% by mass, preferably 0.1 to 2% by mass with respect to the powder polyurethane resin composition.

The slush molding method of the present invention will be described. An example of a specific procedure is as follows. First, a mold release agent is applied to a mold (die) at a temperature of 60 ° C. or less by air spraying, brushing, or the like. Heat. Next, the powder polyurethane resin composition for slush molding of the present invention is charged in a mold and held (powdered) for 15 to 45 seconds, and then the excess powder resin is removed, and usually 20 to 300 seconds, preferably After 30 to 120 seconds in a heating oven at 200 to 400 ° C. to complete the melting of the material, the mold is cooled and removed by a water cooling method or the like to remove a slush molding (usually 0.7 to 2 mm thick). Sheet). In addition, a polyurethane foam stock solution is further introduced into the same mold without taking out the sheet, foamed to form a core material, and then removed from the mold to remove the mold (for example, an automobile) Instrument panel, console box, armrest, etc.). Examples of the polyurethane foam include flexible foam and semi-rigid foam having a density of 0.02 to 0.5 g / cm ³ .

The slush molding obtained by the present invention is particularly suitable as an interior material for automobiles, and is also useful as a material for indoor furniture such as a sofa.

  The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited thereto. In Examples and Comparative Examples, “%” means “mass%”.

(Synthesis of dispersant solution)
Synthesis example 1
Capacity with stirrer, thermometer, distillation column and nitrogen gas inlet tube: 2,000 ml of adipic acid, 49 g of maleic anhydride and 386 g of ethylene glycol were charged into a 2,000 ml reactor, and nitrogen gas was allowed to flow while stirring. The esterification reaction was carried out at ° C and normal pressure. When condensed water no longer appeared, 0.1 g of tetrabutyl titanate was added, the pressure in the reaction system was gradually reduced to 0.07 kPa, and the reaction temperature was gradually increased to 190 ° C. to continue the reaction. The number average molecular weight of the obtained polyester was 2,000, and the iodine value was 12.7 gI / 100 g. Subsequently, 74 g of the above polyester and 150 g of butyl acetate were charged into a reactor having the same capacity as described above: 500 ml. The mixture was heated and stirred until it reached 110 ° C. while flowing nitrogen gas. Thereafter, 75 g of 2-ethylhexyl methacrylate and 1 g of benzoyl peroxide were dropped from the dropping funnel over 1 hour. After completion of the dropwise addition, the temperature was raised to 130 ° C. and the reaction was further continued for 2 hours to obtain a dispersant solution D-1. The solid content of the dispersant solution D-1 was 50%.

[Synthesis of powder polyurethane resin for slush molding]
Example 1
Capacity with stirrer, thermometer, cooler, and nitrogen gas inlet tube: In a 3 L reactor, 430.7 g of polyol-1, 430.7 g of polyol-3, 25.8 g of dispersant solution D-1, 987 g of Kyowasol (registered trademark) C-800 was added as a dispersion medium, and the mixture was uniformly stirred and dispersed at 40 ° C. Next, 106.4 g of HDI and 0.13 g of DOTDL were charged and reacted at 90 ° C. for 3 hours. Next, 19.4 g of 1,4-BD was charged and reacted until the isocyanate group disappeared. Then, it filtered and dried and obtained powder polyurethane resin Pow-1 for slush molding. The average particle size of Pow-1 was 120 μm.

Example 2
In a reactor similar to that in Example 1, 430.7 g of polyol-2, 430.7 g of polyol-3, 25.8 g of dispersant solution D-1 and 987 g of Kyowasol (registered trademark) C-800 were charged. The mixture was uniformly stirred and dispersed at 40 ° C. Next, 106.4 g of HDI and 0.13 g of DOTDL were charged and reacted at 90 ° C. for 3 hours. Next, 19.4 g of 1,4-BD was charged and reacted until the isocyanate group disappeared. Thereafter, filtration and drying were performed to obtain a powder polyurethane resin Pow-2 for slush molding. The average particle size of Pow-2 was 110 μm.

Comparative Example 1
In the same reactor as in Example 1, 430.7 g of polyol-3, 430.7 g of polyol-3, 25.8 g of dispersant solution D-1 and 987 g of Kyowasol (registered trademark) C-800 were charged. The mixture was uniformly stirred and dispersed at 40 ° C. Next, 106.4 g of HDI and 0.13 g of DOTDL were charged and reacted at 90 ° C. for 3 hours. Next, 19.4 g of 1,4-BD was charged and reacted until the isocyanate group disappeared. Thereafter, filtration and drying were performed to obtain a powder polyurethane resin Pow-3 for slush molding. The average particle size of Pow-3 was 120 μm.

Comparative Example 2
In a reactor similar to that in Example 1, 430.7 g of polyol-4, 430.7 g of polyol-3, 25.8 g of the dispersant solution D-1 and 987 g of Kyowasol (registered trademark) C-800 were charged. The mixture was uniformly stirred and dispersed at 40 ° C. Next, 106.4 g of HDI and 0.13 g of DOTDL were charged and reacted at 90 ° C. for 3 hours. Next, 19.4 g of 1,4-BD was charged and reacted until the isocyanate group disappeared. Then, it filtered and dried and obtained powder polyurethane resin Pow-4 for slush molding. The average particle size of Pow-4 was 100 μm.

In Examples 1-2 and Comparative Example 1, polyol-1:
Polyester diol obtained by condensation polymerization of ethylene glycol and lactic acid Number average molecular weight = 2,000
Polyol-2:
Polyester diol obtained by further polycondensing lactic acid to a polyester polyol obtained from 1,4-butanediol having a number average molecular weight of 500 and adipic acid Number average molecular weight = 2,000
Polyol-3:
Polyester diol obtained by condensation polymerization of 1,4-butanediol and adipic acid Number average molecular weight = 2,000
Polyol-4:
Polyether diol obtained by ring-opening addition polymerization of tetrahydrofuran using 1,4-butanediol as an initiator Number average molecular weight = 2,000
1,4-BD:
1,4-butanediol HDI:
Hexamethylene diisocyanate DOTDL:
Dioctyltin dilaurate Kyowasol (registered trademark) C-800:
Isooctane solvent, boiling point 110-120 ° C
* Kyowasol: registered trademark of Kyowa Hakko Kogyo

Measurement of physical properties Pow-1 to 4 obtained in Examples 1 and 2 and Comparative Example 1 were each brought into contact with a mold heated to 220 ° C. for 10 seconds, thermally melted, unmelted powder was removed, and an oven at 350 ° C. was removed. After being left in the inside for 1 minute, it was cooled with water to form a molded sheet having a thickness of 1 mm. The obtained molded sheet was subjected to a performance test by the following test method. The results are shown in Table 1.

〔Test method〕
Appearance: Check for abnormalities such as pinholes on the surface of the obtained sheet.
Y: No abnormality
X: Abnormalities such as pinholes are confirmed.
Strength at break: measured according to JIS K6301.
Elongation: Measured according to JIS K6301.
Biodegradability: The obtained sheet is buried in the soil for half a year, and the appearance of the subsequent sheet is observed.
○: Biodegraded and the sheet shape is not maintained.
Δ: Although biodegraded, the shape of the sheet is maintained.
X: Almost no biodegradation.

From Table 1, the molded products of the examples showed good physical properties and also had biodegradability. On the other hand, the molded product of the comparative example had good mechanical properties but low biodegradability.

Claims (4)

In a powder polyurethane resin for slush molding obtained by reacting a polymer polyol (A) having a number average molecular weight of 500 to 10,000, a chain extender (B) having a number average molecular weight of less than 500, and an organic polyisocyanate (C) From the polyurethane resin for slush molding, characterized in that the polymer polyol (A) contains a lactic acid polyester diol (A1) obtained by polycondensation of lactic acid to a diol having a number average molecular weight of 62 to 5,000. Become a powder material .
The powder material comprising the polyurethane resin for slush molding according to claim 1, wherein the lactic acid polyester diol (A1) has a number average molecular weight of 500 to 10,000.
After the polymer polyol (A) is dispersed in the dispersion medium (E) in the presence of the dispersant (D), it is reacted with the organic polyisocyanate (C) to obtain an isocyanate group-terminated urethane prepolymer dispersion. The method for producing a powder material comprising a polyurethane resin for slush molding according to claim 1 or 2, wherein the chain extension reaction is performed by adding the chain extender (B) to the dispersion.
A slush molding method, comprising: putting the powder polyurethane resin composition for slush molding according to claim 1 or 2 into a heated mold, and then melt molding after removing excess resin.