Biodegradable polyurethane foam for seedling cultivation, seedbed equipped with the biodegradable polyurethane foam for seedling cultivation

Abstract

To provide a technology that enables the production of a polyurethane foam suitable for seedling cultivation while also being biodegradable. [Solution] This technology provides a biodegradable polyurethane foam for seedling cultivation obtained from a composition containing a polyol and a polyisocyanate, wherein the polyol contains a biodegradable polyol, the polyisocyanate contains an aliphatic isocyanate and / or an alicyclic isocyanate, and the number of cells is 5 or more per 25 mm.

Description

[Technical Field]

[0001] This technology relates to a biodegradable polyurethane foam for seedling cultivation. More specifically, it relates to a biodegradable polyurethane foam for seedling cultivation and a seedbed equipped with the biodegradable polyurethane foam for seedling cultivation. [Background technology]

[0002] Polyurethane foam is widely used in various fields, from furniture such as sofas and chairs, bedding such as mattresses and pillows, clothing such as underwear, daily necessities such as dishwashing and cleaning sponges, vehicle and aircraft interior products such as car seats, electronic devices such as mobile phones, cameras, and televisions, electrical equipment such as home appliances, toys, general merchandise, and even seedling beds for hydroponics. Furthermore, various developments are underway to improve quality and add new functions according to each field and purpose.

[0003] For example, Patent Document 1 describes an apparent density of 10 kg / m³. 3 ~40kg / m 3 , stretch less than 30%, breathability 40cc / cm 2 / sec~300cc / cm 2 / sec, compressive strength of 0.8 N / cm 2 ~3.5 N / cm 2 A hydroponic support is disclosed that uses polyurethane foam characterized by a water absorption rate of 10 seconds or less and a water absorption height of 3 mm to 50 mm. This support has sufficient firmness to be used as a support for hydroponic cultivation of fruiting vegetables that bear fruit at the top, such as tomatoes, while also providing an appropriate balance of water and oxygen supply and not inhibiting root growth.

[0004] Furthermore, for example, Patent Document 2 discloses a biodegradable hydrophilic urethane foam for seedling cultivation, obtained by adding a microbiophilic powdered organic filler to the hydrophilic urethane foam. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2004-81189 [Patent Document 2] Japanese Patent Application Publication No. 58-56605 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] In recent years, technologies that utilize biomass raw materials in polyurethane foam or enhance its biodegradability have attracted attention as so-called carbon-neutral renewable resources in order to contribute to the formation of a sustainable society, but further development is still expected. For example, the hydroponic support described in Patent Document 1 mentioned above is not biodegradable, and although the hydrophilic polyurethane foam for seedling cultivation described in Patent Document 2 mentioned above uses biomass raw materials, it has the problem that the polyurethane resin skeleton is not biodegradable because it uses tolylene diisocyanate (TDI), which is an aromatic isocyanate, as the isocyanate.

[0007] Therefore, the main objective of this technology is to provide a technology that can manufacture a polyurethane foam suitable for seedling cultivation while also being biodegradable. [Means for solving the problem]

[0008] The inventors of this application conducted diligent research to solve the aforementioned problems and, as a result, discovered that by using a biodegradable polyol as the polyol and an aliphatic isocyanate and / or alicyclic isocyanate as the polyisocyanate to impart biodegradability, as well as by finding that the number of cells in the polyurethane foam is important for use in seedling cultivation (i.e., to ensure germination), they were able to complete this technology.

[0009] In other words, this technology first provides a biodegradable polyurethane foam for seedling cultivation obtained from a composition containing a polyol and a polyisocyanate, The aforementioned polyol contains a biodegradable polyol, The polyisocyanate contains an aliphatic isocyanate and / or an alicyclic isocyanate. We provide a biodegradable polyurethane foam for seedling cultivation with a cell count of 5 cells / 25 mm or more.

[0010] Furthermore, the biodegradable polyurethane foam for seedling cultivation related to this technology may have an elongation rate of 55% or less, as measured in accordance with JIS K6400-5:2012. When the elongation rate is within this range, even when the seedlings grow to a certain size after germination, the biodegradable polyurethane foam for seedling cultivation can support the seedlings without them falling over (i.e., it has seedling support properties). The biodegradable polyurethane foam for seedling cultivation related to this technology has a density of 50 kg / m³. 3 The following is also acceptable. In the biodegradable polyurethane foam for seedling cultivation relating to this technology, the polyisocyanate may be a trimmer. The biodegradable polyurethane foam for seedling cultivation related to this technology may have a 25% compression stiffness of 10 kPa or less, as measured in accordance with ASTM D 3574-11. The biodegradable polyurethane foam for seedling cultivation related to this technology can be used in seedbeds. [Brief explanation of the drawing]

[0011] [Figure 1] The following are illustrative diagrams of the biodegradable polyurethane foam for seedling cultivation used in the examples to illustrate the germination test method. Figure 1A is a plan view of the biodegradable polyurethane foam for seedling cultivation, Figure 1B is an XX end view, and Figure 1C is an illustrative diagram showing the biodegradable polyurethane foam for seedling cultivation during seedling cultivation. [Figure 2] This graph shows the degree of biodegradation for Examples 1 and 3, and Comparative Example 1. [Figure 3] These are photographs of the appearance of Examples 1 and 2, and Comparative Example 2. [Modes for carrying out the invention]

[0012] Hereinafter, preferred embodiments for implementing the present technology will be described. The embodiments described below show examples of typical embodiments of the present technology, and any of the embodiments can be combined. Also, the scope of the present technology is not construed narrowly by these.

[0013] 1. Composition for producing polyurethane foam The biodegradable polyurethane foam for seedling raising according to the present technology is produced using a composition containing a polyol and a polyisocyanate. The composition used for producing the biodegradable polyurethane foam for seedling raising according to the present technology can also contain a blowing agent, a catalyst, a foam stabilizer, etc., as necessary. Hereinafter, each component will be described in detail.

[0014] (1) Polyol In the present technology, it is characterized in that a biodegradable polyol is used as the polyol component. Also, depending on the physical properties and uses of the polyurethane foam to be produced, one or more polyols used in general polyurethane foams can be freely selected and used within a range that does not impair the actions and effects of the present technology.

[0015] (1-1) Biodegradable polyol As for the biodegradable polyols that can be used in this technology, one or more biodegradable polyols that can be used in the manufacture of polyurethane foam can be freely selected and used, as long as they do not impair the function or effect of this technology. For example, aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and azelaic acid; aliphatic carboxylic acids such as ricinoleic acid; aromatic dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid; alicyclic dicarboxylic acids such as hexahydrophthalic acid, hexahydroterephthalic acid, and hexahydroisophthalic acid; or acid esters or acid anhydrides thereof, and diethylene glycol, trimethylolpropane, ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,8-octanediol, and 1,9-nonanediol Examples include polyester polyols obtained by dehydration condensation reactions with these or by other means (e.g., polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polybutylene adipate terephthalate (PBAT), etc.); polylactone polyols obtained by ring-opening polymerization of lactone monomers such as ε-caprolactone and methyl valerolactone, polycaprolactone (PCL), polyglycolic acid (PGA), polylactic acid (PLA), polyethylene glycol (PEG), polyvinyl alcohol (PVA), polyhydroxyalkanoic acid (PHA), cellulose, cellulose acetate, chitosan, starch, modified starch, xylitol, sorbitol, mannitol, maltitol, castor oil-based polyols, and other naturally derived esters.Among these, in the present technology, aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and azelaic acid, and diethylene glycol, trimethylolpropane, ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, 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, etc., or a polyester polyol obtained by a dehydration condensation reaction with a mixture thereof is preferred. It is more preferable to select a polyester polyol obtained by a dehydration condensation reaction of adipic acid represented by the following chemical formula (1), a mixture of diethylene glycol represented by the following chemical formula (2), and trimethylolpropane represented by the following chemical formula (3).

[0016]

Chem.

[0017]

Chem.

[0018]

Chem.

[0019] The content of the biodegradable polyol in 100 parts by weight of the polyol in the raw material is not particularly limited as long as the functions and effects of the present technology are not impaired, and can be freely set. As the lower limit value of the content of the biodegradable polyol in 100 parts by weight of the polyol in the raw material, for example, it is 50 parts by mass or more, preferably 60 parts by mass or more, more preferably 70 parts by mass or more, and still more preferably 80 parts by mass or more. By setting the lower limit value of the content of the biodegradable polyol within this range, the biodegradability of the produced polyurethane foam can be further improved.

[0020] There is no upper limit to the content of biodegradable polyol in 100 parts by weight of polyol in the raw material; it may be 100 parts by weight.

[0021] (1-2) Polyols other than biodegradable polyols In this technology, polyols other than biodegradable polyols can be used in combination, as long as they do not impair the function or effect of this technology. Examples of polyols other than biodegradable polyols include non-biodegradable polyester polyols, polyether polyols, polyester ether polyols, polycarbonate polyols, polymer polyols, etc.

[0022] (2) Polyisocyanates This technology is characterized by using aliphatic isocyanates and / or alicyclic isocyanates as polyisocyanates. By using biodegradable aliphatic isocyanates and / or alicyclic isocyanates as isocyanates, this technology makes it possible to produce highly biodegradable polyurethane foam. Furthermore, depending on the physical properties and applications of the polyurethane foam to be produced, it is also possible to freely select and use one or more types of polyisocyanates commonly used in polyurethane foam, as long as the effects and benefits of this technology are not impaired.

[0023] (2-1) Aliphatic isocyanates Examples of aliphatic isocyanates include hexamethylene diisocyanate (HDI) shown in chemical formula (4) below, 1,5-pentamethylene diisocyanate (PDI) shown in chemical formula (5) below, trimethylene diisocyanate, 1,2-propylene diisocyanate, butylene diisocyanate (tetramethylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate), pentamethylene diisocyanate, Examples include 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, 2,6-diisocyanate methyl caproate, lysine diisocyanate, trimethylhexamethylene diisocyanate, decamethylene diisocyanate, lysine ester triisocyanate, 1,6,11-undecane triisocyanate, 1,3,6-hexamethylene triisocyanate, and lysine triisocyanate (LTI (2,6-Diisocyanato hexanoic acid 2-isocyanatoethyl ester)).

[0024] [ka]

[0025] [ka]

[0026] (2-2) Alicyclic isocyanates Alicyclic isocyanates include 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate, IPDI), represented by the following chemical formula (6): 1,3-cyclopentane diisocyanate, 1,3-cyclopentene diisocyanate, cyclohexane diisocyanate (1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate), dimer acid diisocyanate, and transcyclo Examples include monocyclic alicyclic isocyanates such as hexane-1,4-diisocyanate, hydrogenated tolylene diisocyanate (hydrogenated TDI), and hydrogenated tetramethylxylylene diisocyanate (hydrated TMXDI); and cross-linked cyclic alicyclic isocyanates such as norbornene diisocyanate, norbornane diisocyanate methyl, diisocyanate methyl bicycloheptane, bicycloheptane triisocyanate, and di(diisocyanate methyl)tricyclodecane.

[0027] [ka]

[0028] Among these, in this technology, it is preferable to select lysine triisocyanate (LTI (2,6-Diisocyanato hexanoic acid 2-isocyanatoethyl ester)) represented by the following chemical formula (7), or its trimer. Among the trimers, it is more preferable to select HDI isocyanurate (HDI trimer, 2,4,6-trioxo-1,3,5-triazine-1,3,5-triyltris(6,1-hexanediyl)triisocyanate) represented by the following chemical formula (8), which is a trimer of hexamethylene diisocyanate (HDI), or 1,5-PDI isocyanurate (PDI) represented by the following chemical formula (9).

[0029] [ka]

[0030] [ka]

[0031] [ka]

[0032] (2-3) Other polyisocyanates In this technology, polyisocyanates other than aliphatic and alicyclic isocyanates can also be used in combination, to the extent that they do not impair the action or effect of this technology. Examples of polyisocyanates other than aliphatic and alicyclic isocyanates include aromatic isocyanates such as toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthalene diisocyanate, xylylene diisocyanate, and polymethylene polyphenyl polyisocyanate (polymeric MDI); and modified polyisocyanates obtained by modifying these.

[0033] The isocyanate index of the polyurethane foam is not particularly limited, as long as it does not impair the function or effect of this technology. In this technology, the lower limit of the isocyanate index is, for example, 80 or more, preferably 85 or more, and more preferably 90 parts by mass or more. By setting the lower limit of the isocyanate index within this range, the strength of the polyurethane foam produced can be improved.

[0034] The upper limit of the isocyanate index is, for example, 120 or less, preferably 115 or less, and more preferably 110 or less. By setting the upper limit of the isocyanate index within this range, it is possible to prevent the polyurethane foam from becoming too hard, brittle, and losing its flexibility, and to improve the elasticity of the polyurethane foam.

[0035] In this technology, the isocyanate index is calculated using the formula [(equivalent amount of polyisocyanate in the polyurethane foam manufacturing composition / equivalent amount of active hydrogen in the polyurethane foam manufacturing composition) × 100].

[0036] (3) Foaming agent A blowing agent can be used in the manufacture of polyurethane foam according to this technology. As long as the purpose and effects of this technology are not impaired, one or more blowing agents that can be used in the manufacture of polyurethane foam can be freely selected and used.

[0037] Examples of foaming agents include water, hydrocarbons, and halogenated compounds. Examples of hydrocarbons include cyclopentane, isopentane, and n-pentane. Examples of halogenated compounds include methylene chloride, trichlorofluoromethane, dichlorodifluoromethane, nonafluorobutyl methyl ether, nonafluorobutyl ethyl ether, pentafluoroethyl methyl ether, and heptafluoroisopropyl methyl ether. In this technology, water is preferred as the foaming agent among these. The water may be deionized water, tap water, or distilled water.

[0038] The amount of foaming agent used in the production of polyurethane foam according to this technology can be freely set as long as it does not impair the function or effect of this technology. In this technology, the lower limit of the foaming agent content in the composition is, for example, 0.1 parts by mass or more, preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more, per 100 parts by mass of polyol. By setting the lower limit of the foaming agent content in the composition within this range, foamability can be improved, and as a result, polyurethane foam with excellent mechanical properties and appearance can be obtained.

[0039] In this technology, the upper limit of the foaming agent content in the composition is, for example, 20 parts by mass or less, preferably 15 parts by mass or less, and more preferably 10 parts by mass or less, per 100 parts by mass of polyol. By setting the upper limit of the foaming agent content in the composition within this range, it is possible to suppress formation defects due to excessive foaming.

[0040] (4) Catalyst A catalyst can be used in the production of polyurethane foam according to this technology. As for the catalyst that can be used in this technology, one or more catalysts that can be used in the production of polyurethane foam can be freely selected and used, as long as they do not impair the action or effect of this technology.

[0041] Examples of catalysts include metal catalysts (organometallic catalysts) such as organotin compounds (dibutyltin dilaurate, tin octoate, tin 2-ethylhexanoate, etc.), organoiron compounds (iron acetylacetonate, etc.), organoniceric compounds (nickel acetylacetonate, nickel octoate, nickel naphthenate, etc.), organobismuth compounds (bismuth octoate, bismuth naphthenate, etc.), organolead compounds (lead octanoate, lead naphthenate, etc.), organocobalt compounds (cobalt acetylacetonate, cobalt octoate, cobalt naphthenate, etc.), organozirconium compounds (zirconium acetylacetonate, etc.), and organozinc compounds, as well as triethylamine, triethylenediamine (TEDA), tetramethylguanidine, diethanolamine, and bis(2-dimethylaminoethyl Examples of amine catalysts include ethers, N,N,N′,N″,N″-pentamethyldiethylenetriamine, imidazole compounds, piperazine amines such as N,N'-dimethylpiperazine, N,N',N'-trimethylaminoethylpiperazine, N-methyl-N'-(2-dimethylamino)ethylpiperazine, and N-methyl-N'-(2-hydroxyethyl)piperazine, morpholine amines such as N-methylmorpholine and N-ethylmorpholine, and amines referred to as DBU congeners such as 1,8-diazabicyclo-[5,4,0]-undecene-7 (DBU), 1,5-diazabicyclo-[4,3,0]-nonene-5 (DBN), 1,8-diazabicyclo-[5,3,0]-decene-7 (DBD), and 1,4-diazabicyclo-[3,3,0]octene-4 (DBO). In this technology, it is preferable to use one or more catalysts selected from organotin compounds, piperazine amines, morpholine amines, and DBU congeners, and it is more preferable to select one or more catalysts selected from dibutyltin dilaurate, N,N'-dimethylpiperazine, N,N',N'-trimethylaminoethylpiperazine, and N-ethylmorpholine 1,8-diazabicyclo-[5,4,0]-undecene-7(DBU).

[0042] The amount of catalyst in the composition used to manufacture the polyurethane foam according to this technology can be freely set as long as it does not impair the function or effect of this technology. In this technology, the lower limit of the catalyst content in the composition is, for example, 0.1 parts by mass or more, preferably 0.5 parts by mass or more, and more preferably 1.0 part by mass or more, per 100 parts by mass of polyol. By setting the lower limit of the catalyst content in the composition within this range, various reactions during manufacturing can be controlled, and as a result, polyurethane foam with excellent mechanical properties and appearance can be obtained.

[0043] In this technology, the upper limit of the catalyst content in the composition is, for example, 10 parts by mass or less, preferably 9 parts by mass or less, and more preferably 8 parts by mass or less, per 100 parts by mass of polyol. By setting the upper limit of the catalyst content in the composition within this range, it is possible to prevent destabilization of various reactions during manufacturing. As a result, polyurethane foam with excellent mechanical properties and appearance can be obtained.

[0044] (5) Foam stabilizers A foam stabilizer can be used in the manufacturing of polyurethane foam related to this technology. By using a foam stabilizer, a higher quality polyurethane foam can be manufactured.

[0045] As foam stabilizers that can be used in this technology, one or more types of foam stabilizers that can be used in the manufacture of polyurethane foam may be freely selected and used, as long as they do not impair the function or effect of this technology. Examples include silicone-based foam stabilizers, fluorine-containing compound-based foam stabilizers, surfactants, etc. Examples of silicone-based foam stabilizers include those mainly composed of siloxane chains, those in which siloxane chains and polyether chains form a linear structure, those that are branched and separated, and those in which polyether chains are modified into a pendant-like structure of siloxane chains.

[0046] The amount of the foam stabilizer in the composition used for producing the polyurethane foam according to the present technology can be freely set as long as the functions and effects of the present technology are not impaired. The lower limit of the content of the foam stabilizer in the composition is, for example, 0.1 part by mass or more, preferably 0.5 part by mass or more, based on 100 parts by mass of the polyol. The upper limit of the content of the foam stabilizer in the composition is, for example, 10 parts by mass or less, preferably 7 parts by mass or less, more preferably 5 parts by mass or less, based on 100 parts by mass of the polyol.

[0047] (6) Others For the production of the polyurethane foam according to the present technology, as long as the functions and effects of the present technology are not impaired, as other components, various components that can be used for the production of the polyurethane foam can be freely selected and used singly or in combination of two or more according to the purpose.

[0048] Examples of the components that can be used for the production of the polyurethane foam according to the present technology include flame retardants, pigments, stabilizers, plasticizers, colorants, crosslinking agents, antibacterial agents, dispersants, fillers, antioxidants, ultraviolet absorbers, and the like.

[0049] 2. Polyurethane Foam for Biodegradable Seedling Raising The polyurethane foam for biodegradable seedling raising according to the present technology can be produced using the composition described above. Hereinafter, the physical properties and the like of the polyurethane foam for biodegradable seedling raising according to the present technology will be described in detail.

[0050] (1) Density The density of the polyurethane foam for biodegradable seedling raising according to the present technology can be freely set as long as the functions and effects of the present technology are not impaired. The lower limit of the density of the polyurethane foam for biodegradable seedling raising according to the present technology is, for example, 20 kg / m 3 or more, preferably 25 kg / m 3 or more, more preferably 27 kg / m 3 or more. By setting the lower limit of the density of the polyurethane foam for biodegradable seedling raising within this range, the supportability of the seedlings and the like can be improved.

[0051] The upper limit of the density of the biodegradable polyurethane foam for seedling cultivation related to this technology is, for example, preferably 50 kg / m³. 3 More preferably 48 kg / m 3 More preferably 45 kg / m 3 The following is the case: By keeping the density of the biodegradable polyurethane foam for seedling cultivation within this range, it is possible to improve seedling cultivation properties such as germination rate and root growth without compromising the flexibility of the biodegradable polyurethane foam for seedling cultivation (preventing it from becoming hard).

[0052] In this technology, the density is the value measured by the method described in the examples below.

[0053] (2) 25% compression hardness The 25% compression hardness of the biodegradable polyurethane foam for seedling cultivation related to this technology can be freely set as long as it does not impair the function or effect of this technology. The upper limit of the 25% compression hardness of the biodegradable polyurethane foam for seedling cultivation related to this technology is, for example, 10 kPa or less, preferably 7.0 kPa or less. By setting the upper limit of the 25% compression hardness of the biodegradable polyurethane foam for seedling cultivation within this range, seedling cultivation properties such as germination rate and root growth can be improved.

[0054] The lower limit of the 25% compression stiffness of the biodegradable polyurethane foam for seedling cultivation related to this technology is, for example, 1.0 kPa or higher, preferably 1.5 kPa or higher, and more preferably 2.0 kPa or higher. By setting the lower limit of the 25% compression stiffness of the biodegradable polyurethane foam for seedling cultivation within this range, the support for seedlings and other properties can be improved.

[0055] In this technology, the 25% compression hardness is the value measured by the method described in the examples below.

[0056] (3) Rebound modulus The rebound modulus of the biodegradable polyurethane foam for seedling cultivation according to this technology can be freely set as long as it does not impair the function or effect of this technology. The lower limit of the rebound modulus of the biodegradable polyurethane foam for seedling cultivation according to this technology is, for example, 15% or more, preferably 18% or more, and more preferably 20% or more. The upper limit of the rebound modulus of the biodegradable polyurethane foam for seedling cultivation according to this technology is, for example, 40% or less, preferably 35% or less, and more preferably 30% or less.

[0057] In this technology, the rebound modulus is the value measured by the method described in the examples below.

[0058] (4) Tensile strength The tensile strength of the biodegradable polyurethane foam for seedling cultivation according to this technology can be freely set as long as it does not impair the function or effect of this technology. The lower limit of the tensile strength of the biodegradable polyurethane foam for seedling cultivation according to this technology is, for example, 20 kPa or more, preferably 24 kPa or more, and more preferably 25 kPa or more. By setting the lower limit of the tensile strength of the biodegradable polyurethane foam for seedling cultivation within this range, seedling cultivation performance such as germination rate can be improved. The upper limit of the tensile strength of the biodegradable polyurethane foam for seedling cultivation according to this technology is not particularly limited as long as it does not impair the function or effect of this technology, and is, for example, 100 kPa or less.

[0059] In this technology, the tensile strength is the value measured by the method described in the examples below.

[0060] (5) Growth rate The elongation rate of the biodegradable polyurethane foam for seedling cultivation related to this technology can be freely set as long as it does not impair the function or effect of this technology. The upper limit of the elongation rate of the biodegradable polyurethane foam for seedling cultivation related to this technology is, for example, 150% or less, preferably 100% or less, and more preferably 60% or less. By setting the upper limit of the elongation rate of the biodegradable polyurethane foam for seedling cultivation within this range, seedling cultivation performance such as germination rate can be improved.

[0061] In particular, the upper limit of the elongation rate of the biodegradable polyurethane foam for seedling cultivation related to this technology is preferably 55% or less, from the viewpoint of ensuring seedling support in addition to seedling cultivation performance. When the elongation rate is within this range, even when the seedlings grow to a certain size after germination, the biodegradable polyurethane foam for seedling cultivation does not lose its shape and can support the seedlings in an upright position without them falling over (i.e., it has seedling support properties).

[0062] Furthermore, there is no particular limit to the elongation rate of the biodegradable polyurethane foam for seedling cultivation related to this technology, as long as it does not impair the function or effect of this technology. However, it may be, for example, 30% or more, preferably 35% or more, and more preferably 36% or more.

[0063] In this technology, the elongation rate is the value measured by the method described in the examples below.

[0064] (6) Tear strength The tear strength of the biodegradable polyurethane foam for seedling cultivation according to this technology can be freely set as long as it does not impair the function or effect of this technology. The lower limit of the tear strength of the biodegradable polyurethane foam for seedling cultivation according to this technology is, for example, 2.0 N / cm or more, preferably 2.1 N / cm or more, more preferably 2.2 N / cm or more, and even more preferably 2.3 N / cm or more. By setting the lower limit of the tear strength of the biodegradable polyurethane foam for seedling cultivation within this range, the support for seedlings can be improved.

[0065] The upper limit of the tear strength of the biodegradable polyurethane foam for seedling cultivation according to this technology is, for example, 4.0 N / cm or less, preferably 3.5 N / cm or less, and more preferably 3.0 N / cm or less. By setting the upper limit of the tear strength of the biodegradable polyurethane foam for seedling cultivation within this range, seedling cultivation performance such as germination rate can be improved.

[0066] In this technology, the tear strength is the value measured by the method described in the examples below.

[0067] (7) Number of cells The biodegradable polyurethane foam for seedling cultivation according to this technology is characterized by having 5 or more cells per 25 mm. The inventors of this application have found that when polyurethane foam is used for seedling cultivation, it is necessary to have 5 or more cells per 25 mm.

[0068] The number of cells in the biodegradable polyurethane foam for seedling cultivation can be freely set as long as it is 5 cells / 25 mm or more, without impairing the function or effect of this technology. The lower limit of the number of cells in the polyurethane foam related to this technology is preferably 10 cells / 25 mm or more, more preferably 15 cells / 25 mm or more, even more preferably 20 cells / 25 mm or more, and even more preferably 30 cells / 25 mm or more. By setting the lower limit of the number of cells in the biodegradable polyurethane foam for seedling cultivation within this range, seedling cultivation performance such as germination rate can be improved.

[0069] The upper limit of the number of cells in the polyurethane foam relating to this technology is, for example, 70 cells / 25 mm or less, preferably 65 cells / 25 mm or less, and more preferably 60 cells / 25 mm or less.

[0070] In this technology, the number of cells is the value measured by the method described in the examples below.

[0071] (8) Water retention rate The water retention rate of the biodegradable polyurethane foam for seedling cultivation according to this technology can be freely set as long as it does not impair the function or effect of this technology. The lower limit of the water retention rate of the biodegradable polyurethane foam for seedling cultivation according to this technology after 3 hours is, for example, 15% or more, preferably 20% or more, more preferably 25% or more, even more preferably 30% or more, and even more preferably 35% or more. By setting the lower limit of the water retention rate of the biodegradable polyurethane foam for seedling cultivation after 3 hours within this range, seedling cultivation performance such as germination rate can be improved.

[0072] The upper limit of the water retention rate of the biodegradable polyurethane foam for seedling cultivation after 3 hours according to this technology is, for example, 80% or less, preferably 75% or less, and more preferably 70% or less. By setting the upper limit of the water retention rate of the biodegradable polyurethane foam for seedling cultivation after 3 hours within this range, seedling cultivation problems caused by excessive moisture, such as root rot, can be suppressed.

[0073] In this technology, the water retention rate is the value measured by the method described in the examples below.

[0074] (9) Biodegradability The degree of biodegradation of the biodegradable polyurethane foam for seedling cultivation according to this technology is not particularly limited as long as it does not impair the function or effect of this technology. The lower limit of the degree of biodegradation of the biodegradable polyurethane foam for seedling cultivation according to this technology after 60 days is, for example, 20% or more, preferably 30% or more, more preferably 40% or more, even more preferably 50% or more, and even more preferably 60% or more. Having the lower limit of the degree of biodegradation of the biodegradable polyurethane foam for seedling cultivation after 60 days within this range contributes to reducing the environmental burden.

[0075] The upper limit of the biodegradability of the biodegradable polyurethane foam for seedling cultivation after 60 days according to this technology is, for example, 95% or less, preferably 90% or less, and more preferably 85% or less. By setting the upper limit of the biodegradability of the biodegradable polyurethane foam for seedling cultivation after 60 days within this range, it is possible to prevent the polyurethane foam from decomposing too much during seedling cultivation and to improve the support of seedlings.

[0076] In this technology, the degree of biodegradation is the value measured by the method described in the examples below.

[0077] 3. Seedbed equipped with biodegradable polyurethane foam for seedling cultivation. The biodegradable polyurethane foam for seedling cultivation related to this technology can be used in all seedling cultivation methods, but it is particularly well-suited for use in seedbeds for hydroponic cultivation. Hydroponics is a cultivation method in which plants are grown using water and liquid fertilizer as needed, without the use of soil, and the biodegradable polyurethane foam for seedling cultivation related to this technology is very suitable for methods in which part or all of the seedling cultivation period is carried out hydroponically.

[0078] More specifically, examples include a method in which seedlings are grown hydroponically from sowing to germination using a seedbed made of biodegradable polyurethane foam for seedling cultivation, and then transplanted into soil along with the seedbed once the roots have developed to a certain extent, or a method in which sowing, germination, seedling cultivation, and harvesting are all carried out hydroponically using a seedbed made of biodegradable polyurethane foam for seedling cultivation. The biodegradable polyurethane foam for seedling cultivation related to this technology biodegrades within a certain period after being transplanted into soil, thus improving the recyclability of the cultivation soil after use. Furthermore, while general hydroponic seedbeds require disposal by incineration or other methods after use, the biodegradable polyurethane foam for seedling cultivation related to this technology is biodegradable, making disposal after use easy and contributing to a reduction in disposal costs.

[0079] 4. Method for manufacturing biodegradable polyurethane foam for seedling cultivation The biodegradable polyurethane foam for seedling cultivation related to this technology can be manufactured by mixing the components of the polyurethane foam manufacturing composition described above to prepare a composition, and then proceeding with resinification and foaming reactions. The resinification and foaming reactions can be carried out using any combination of general methods, as long as they do not impair the function and effects of this technology.

[0080] In the method for producing biodegradable polyurethane foam for seedling cultivation related to this technology, any of slab foaming, batch foaming, or mold foaming can be employed. Slab foaming is a method in which a polyurethane foam manufacturing composition (raw material for polyurethane foam) is mixed and cast onto a moving conveyor, and foamed at atmospheric pressure and room temperature. Batch foaming is a method in which the mixture is extruded into a foaming box and foamed at atmospheric pressure and room temperature. On the other hand, mold foaming is a method in which a polyurethane foam manufacturing composition (raw material for polyurethane foam) is mixed and injected into the cavity of a mold (molding mold), and foamed into the shape of the cavity.

[0081] Furthermore, this technology can be configured as follows: [1] A biodegradable polyurethane foam for seedling cultivation obtained from a composition containing a polyol and a polyisocyanate, The aforementioned polyol contains a biodegradable polyol, The polyisocyanate contains an aliphatic isocyanate and / or an alicyclic isocyanate. A biodegradable polyurethane foam for seedling cultivation with a cell count of 5 cells / 25 mm or more. [2] A polyurethane foam for seedling cultivation as described in [1], wherein the elongation rate measured in accordance with JIS K6400-5:2012 is 55% or less. [3] Density of 50 kg / m³ 3 The following is a biodegradable polyurethane foam for seedling cultivation as described in [1] or [2]. [4] The polyisocyanate is a trimmer, as described in any one of [1] to [3], for biodegradable polyurethane foam for seedling cultivation. [5] A biodegradable polyurethane foam for seedling cultivation as described in any of [1] to [4], wherein the 25% compression stiffness measured in accordance with ASTM D 3574-11 is 10 kPa or less. [6] A seedbed comprising a biodegradable polyurethane foam for seedling cultivation as described in any one of items [1] to [5]. [Examples]

[0082] The present technology will be described in more detail below based on the following examples. The examples described below are representative examples of the present technology and should not be interpreted as narrowing the scope of the present technology.

[0083] (1) Raw materials The raw materials used in this embodiment are as follows: Polyol 1; Biodegradable polyol (polyester polyol (COIM "DG173R")), hydroxyl value: 60.5 mg KOH / g, number of functional groups: 2.6, molecular weight: 2400 Polyol 2; Polyether polyol (Sanyo Chemical Industries, Ltd. "GP3050NS"), Hydroxyl value: 56.1 mg KOH / g, Number of functional groups: 3, Molecular weight: 3000 Foaming agent; water Catalyst 1: N-ethylmorpholine Catalyst 2: N,N',N'-trimethylaminoethylpiperazine Catalyst 3: N,N'-dimethylpiperazine Catalyst 4; 1,8-diazabicyclo[5.4.0]undecene-7 Catalyst 5; 1,8-Diazabicyclo[5.4.0]undecene-7 / 2-ethylhexanoate Catalyst 6; N,N',N'-trimethyl-N'-(3-aminopropyl)bis(2-aminoethyl) ether Catalyst 7: Triethylenediamine 33% + Propylene Glycol 67% Catalyst 8; Dibutyltin dilaurate Foam stabilizers; silicone-based foam stabilizers Isocyanate 1; Trimer of hexamethylene diisocyanate (HDI) Isocyanate 2; 1,5-Pentamethylene diisocyanate (PDI) trimmer Isocyanate 3; Toluene diisocyanate (TDI) Isocyanate 4; Isophorone diisocyanate (IPDI)

[0084] (2) Manufacturing of polyurethane foam Each component except the isocyanate shown in Table 1 was mixed in the proportions shown in Table 1. The isocyanate was then added and mixed, and the mixture was injected into a 170 mm square, open-topped, non-sealed foam box and allowed to foam. After foaming, the foam box containing the foam was placed in a 70°C constant temperature bath to cure, thereby obtaining polyurethane foam.

[0085] (3) Measurement and evaluation of physical properties The various physical properties of the manufactured polyurethane foam were measured using the following method. [density] Density was measured using a method compliant with JIS K7222:2005.

[0086] [25% compression hardness] The 25% compression hardness was measured according to the method compliant with ASTM D 3574-11.

[0087] [Rebound modulus] The rebound modulus was measured using a method compliant with JIS K 6400-3:2011.

[0088] [Tensile strength] Tensile strength was measured according to the method compliant with JIS K 6400-5:2012.

[0089] [Growth rate] The elongation rate was measured using a method compliant with JIS K 6400-5:2012.

[0090] [Tear strength] Tear strength was measured according to the method compliant with JIS K 6400-5:2012.

[0091] [Number of cells] The number of cells was measured according to the method specified in the JIS K 6400-1 Annex.

[0092] [Water retention rate] A 25mm x 25mm x 30mm sample was taken from the manufactured polyurethane foam and placed in a tray. 10g of water was added to each sample, and the weight was measured every 30 minutes in a 50°C constant temperature bath. The water retention rate was calculated from the weight immediately after water absorption and the weight after 3 hours.

[0093] [Germination ability] As shown in Figure 1, eight holes H were made in the manufactured polyurethane foam U, and a cross-shaped slit was created. Three green onion seeds S (Atariya Farm Co., Ltd. "All-purpose green onion") were sown in each hole H, and the polyurethane foam U was filled with water to about half its height (see Figure 1C). The number of germinated seeds was measured three days after sowing in a room maintained at 25°C, and the germination rate was calculated. A germination rate of 90% or more was evaluated as ○, a germination rate of 50% or more but less than 90% as △, and a germination rate of less than 50% as ×.

[0094] [Supportability] For Examples 1-3, the support provided to seedlings by polyurethane foam 14 days after sowing was evaluated. If, 14 days after sowing, the grown seedlings were supported by the polyurethane foam without falling over, it was judged as having "good support." Conversely, if the polyurethane foam was deformed and could not support the grown seedlings, it was judged as having "no support." In Table 1 below, "○" indicates good support, and "×" indicates poor support.

[0095] [Biodegradability] The degree of biodegradability was measured using a method compliant with ISO 14855-2.

[0096] (4) Results The biodegradation rates of Examples 1 and 3 and Comparative Example 1 are shown in Figure 2, the appearance photographs of Examples 1 and 2 and Comparative Example 2 are shown in Figure 3, and other results are shown in Table 1 below. [Table 1]

[0097] (5) Discussion As shown in Table 1, Comparative Example 1, which used a polyether polyol, exhibited good germination properties, but as shown in Figure 2, it did not exhibit biodegradability. Furthermore, even though Comparative Example 2 used a biodegradable polyol and an aliphatic isocyanate, it had 4 cells / 25 mm and exhibited biodegradability but did not exhibit germination properties. In contrast, Examples 1 to 3, which were produced using a biodegradable polyol and an aliphatic isocyanate and / or alicyclic isocyanate and had 5 or more cells / 25 mm, exhibited excellent germination properties and biodegradability.

[0098] Comparing the examples, it was confirmed that Examples 1 and 2, with elongation rates of 55% or less, provided support even for seedlings that had grown to a certain size, while Example 3 lacked support. In the case of Example 3, although there were no problems with seedling germination and seedling support (for about a week after germination), the elongation rate was very high at 146%, so as the seedlings grew larger, it became impossible to support them in an upright position. From these results, it was found that for polyurethane foam used for biodegradable seedling cultivation, an elongation rate of 55% or less is preferable, and that trimmer polyisocyanates are preferable.

Claims

1. A biodegradable polyurethane foam for seedling cultivation obtained from a composition containing a polyol and a polyisocyanate, The aforementioned polyol contains a biodegradable polyol, The polyisocyanate contains an aliphatic isocyanate and / or an alicyclic isocyanate. A biodegradable polyurethane foam for seedling cultivation, with a cell count of 5 cells / 25 mm or more.

2. The biodegradable polyurethane foam for seedling cultivation according to claim 1, wherein the elongation rate measured in accordance with JIS K6400-5:2012 is 55% or less.

3. Density of 50 kg / m³ ３ The following is a biodegradable polyurethane foam for seedling cultivation according to claim 1.

4. The polyisocyanate is a trimmer, as described in claim 1, for the biodegradable polyurethane foam for seedling cultivation.

5. The biodegradable polyurethane foam for seedling cultivation according to claim 1, wherein the 25% compression hardness measured in accordance with ASTM D 3574-11 is 10 kPa or less.

6. A seedbed comprising a biodegradable polyurethane foam for seedling cultivation according to any one of claims 1 to 5.

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