JP6733155B2 - Support material for additive manufacturing and method for manufacturing additive manufacturing using the same - Google Patents

Description

The present invention, layered manufacturing for supporting material to be used in the laminate shaping removed (hereinafter, referred to as "support material".) And relates to a manufacturing method of a product layer shaped article using the same, more specifically Relates to a support material for additive manufacturing having low hygroscopicity and excellent molding stability.
In the present invention, the model material refers to the material of the modeled article itself, and the support material refers to the support forming material for facilitating the formation of the modeled article of the modeled material. It is often removed later.

Laminated molding is a method of molding a solid body having a predetermined structure.After a material in a fluid state is extruded, it is instantly solidified, and the material is further laminated on the article to form an article. Is Rukoto. Although a UV curing method, a hot melt laminating method, and the like have been proposed as a layered modeling method, the hot melt layering method has been widely studied because of the simple structure of the device and the fact that the final product can be actually molded.

The support material used in the layered manufacturing method by the hot melt layering method is a material used for layered modeling of a solid body, and refers to a material that covers a portion that does not exist in the target three-dimensional structure. Some three-dimensional bodies to be layered have various structures, and some of them include parts that cannot be formed unless they are supported by some other material in the process of being formed. The support material is used in the modeling process to support such a three-dimensional part, and is eventually removed.

Conventionally, various materials have been studied as support materials used in additive manufacturing, and as the support materials, there are those that are mainly dissolved in a liquid after modeling, those that are scraped off, those that are scraped off, and those that are blown off with a liquid or gas. ..
When scraping off, if the three-dimensional object has a complicated shape, it is difficult to scrape it off so that the three-dimensional object is not scratched, and if it is blown off, the strength of the support material itself is insufficient and sufficient support is not provided. There was a problem that I could not. From such a point, a support material that can be dissolved in a liquid and removed has been proposed (Patent Document 1).

In addition, as a water-soluble resin that can be easily washed and removed and used as the support material, a polyvinyl alcohol (hereinafter, abbreviated as “PVA”) resin has been proposed (Patent Document 2). In particular, Patent Document 2 proposes to add a styrene-ethylene-butylene-styrene block copolymer (SEBS) in order to impart flexibility to the amorphous PVA-based resin. The above-mentioned non-crystalline water-soluble resin is excellent in that it has little shrinkage when cooled and solidified, and has good shape reproducibility.

JP, 2014-24329, A US 2011/0060445 Publication

However, the support material using a PVA-based resin as the water-soluble resin that can be removed by washing with water is apt to absorb moisture in the PVA-based resin itself, so that the support material absorbs moisture after a lapse of time after being installed in the modeling apparatus, As a result, it is difficult to perform stable molding (lamination molding) due to problems such as evaporation of water in the support material and foaming during lamination molding at high temperature. As described above, the materials so far are not satisfactory as support materials, and there is still room for improvement.

The present invention, such problems, i.e., an object to provide a method for producing a low hygroscopicity and molding stability in excellent laminate shaping for support material and the product layer shaped article using the same.

As a result of intensive studies in view of the above-mentioned circumstances, the present invention has conceived to blend silica having certain properties as an inorganic filler in order to impart low hygroscopicity to PVA-based resins. That is, by using a specific silica having a physical property of BET specific surface area of 15 to 350 m ² /g, it was found that the low hygroscopicity of the support material is improved, and as a result, the molding stability is improved, The invention was completed.

The mechanism of expression of the above effect (low hygroscopic effect) is estimated as follows. That is, by using silica having a BET specific surface area of 15 to 350 m ² /g, the hydroxyl groups of the PVA-based resin will face the silica aggregate side, and the hydrophobicity of the surface of the molded article will be increased. It is presumed that the humidity absorption is reduced. As a result, the molding stability of the support material extruded in a molten state at the time of additive manufacturing is improved.

<Summary of Invention>
The present invention contains a PVA-based resin (a) and a silica (b) having a BET specific surface area of 15 to 350 m ² /g, and the content of the silica (b) is 100% by weight of the polyvinyl alcohol-based resin (a). 0.1 to 15 parts by weight, the content of the polyvinyl alcohol resin (a) is 45 to 95% by weight of the whole support material, and the content of silica (b) is the amount of the whole support material. 0.1 to 10 wt% der Ru layered manufacturing for the support member to the first aspect.

Then, the present invention is the first aspect is a laminate shaping support material and the model material successively laminated in a fluid state, after solidification, a method for manufacturing a laminated molded article of removing the support member second The summary of

As described above, the present invention contains the PVA-based resin (a) and the silica (b) having a BET specific surface area of 15 to 350 m ² /g, and the content of the silica (b) is the polyvinyl alcohol-based resin (a). ) 0.1 to 15 parts by weight with respect to 100 parts by weight, the content of the polyvinyl alcohol resin (a) is 45 to 95% by weight of the entire support material, and the content of silica (b) is the support. Ru 0.1 to 10 wt% der of the total wood is layered manufacturing for support material. Therefore, it is possible to obtain a support material having excellent low hygroscopicity and molding stability. Therefore, in the method for producing a layered product by sequentially stacking the support material for layered modeling and the model material of the present invention in a fluidized state and solidifying, and then removing the support material, a stable layered product Can be produced.

Furthermore, when a block copolymer (c) having at least one of a polymer block of an aromatic vinyl compound, a polymer block of a conjugated diene compound and a hydrogenated block thereof, and further having a functional group reactive with a hydroxyl group is contained, The molding stability of the support material extruded in a molten state during the additive manufacturing is further improved.

Further, when the content of the block copolymer (c) is 5 to 100 parts by weight with respect to 100 parts by weight of the PVA-based resin (a), it becomes possible to impart molding stability, and it is possible to obtain a good compatibility with the model material. Adhesion is also improved.

Then, the PVA-based resin (a) is a PVA-based resin containing a structural unit having a primary hydroxyl group in its side chain, and particularly a structural unit having a primary hydroxyl group in its side chain has a 1,2-diol structure in its side chain. When it is a unit, the affinity with the model material is improved, the adhesive force with the model material is improved, and the affinity with the block copolymer (c) is also excellent.

The additive manufacturing support material of the present invention is obtained by using the PVA-based resin (a) which is a matrix component and a specific silica (b). Further, preferably, in addition to these components, a block copolymer having at least one of a polymer block of an aromatic vinyl compound, a polymer block of a conjugated diene compound and its hydrogenated block, and a block copolymer having a functional group capable of reacting with a hydroxyl group. Obtained using the polymer (c).

[PVA-based resin (a)]
The PVA-based resin (a) is a resin having a vinyl alcohol structural unit as a main component, which is obtained by saponifying a polyvinyl ester-based resin obtained by copolymerizing a vinyl ester-based monomer, and has a saponification degree corresponding to vinyl. It is composed of an alcohol structural unit and a vinyl ester structural unit remaining without being saponified.

Examples of the vinyl ester-based monomer include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate. , Vinyl versatate, etc., but vinyl acetate is preferably used economically.

The average degree of polymerization of the PVA-based resin (a) (measured in accordance with JIS K6726) is usually 150 to 4000, preferably 200 to 2000, particularly preferably 250 to 800, and further preferably. It is 300-600.
If the average degree of polymerization is too low, it tends to be difficult to form a stable shape during lamination, and if it is too high, the viscosity of the entire material tends to be too high and melt molding tends to be difficult.

In addition, the viscosity of an aqueous solution may be used as an index of the degree of polymerization of the PVA-based resin (a), and the viscosity of the aqueous solution of the PVA-based resin (a) is usually 1.5 to 20 mPa·s. , Preferably 2 to 12 mPa·s, and particularly preferably 2.5 to 8 mPa·s. If the viscosity is too low, it tends to be difficult to form a stable shape during lamination, and if it is too high, the viscosity of the entire material tends to be too high and melt molding tends to be difficult.
In addition, in the present invention, the viscosity of the aqueous solution of the PVA-based resin (a) is the viscosity of the 4 wt% aqueous solution at 20° C. measured according to JIS K6726.

The degree of saponification of PVA-based resin (a) (measured in accordance with JIS K6726) is usually 70 mol% or more, preferably 75 to 99.7 mol%, and particularly preferably 85 to 99.5. Mol%. If the saponification degree is too low, the flexibility of the PVA-based resin becomes too high, and the shape stability during lamination tends to decrease.

The melting point of the PVA-based resin (a) is usually 120 to 230°C, preferably 150 to 220°C, and particularly preferably 190 to 210°C. If the melting point is too high, the processing temperature at the time of additive manufacturing may increase and the resin may deteriorate. If it is too low, the PVA-based resin may not be melt-discharged from the nozzle during the lamination.

In the case of a normal PVA-based resin, the main chain bonding mode is mainly 1,3-diol bonds, and the content of 1,2-diol bonds in the main chain is 1.5 to 1.7 mol%. The content can be increased by increasing the polymerization temperature at the time of polymerizing the vinyl ester-based monomer to a degree, and the content is 1.8 mol% or more, and further 2.0 to 3.5. It is preferable to have it in a mol %, for example, from the viewpoint of improving the affinity with the block copolymer (c) described later.

Further, as the PVA-based resin (a), various monomers were copolymerized at the time of production of the vinyl ester-based resin and saponified, or various functional groups were introduced into unmodified PVA by post-modification. Various modified PVA-based resins can be used. Such modification can be performed within a range in which the water solubility of the PVA-based resin (a) is not lost, and is usually 20 mol% or less, preferably 10 mol% or less, particularly preferably 5 mol% or less.

Examples of the monomer used for the copolymerization with the vinyl ester-based monomer include ethylene, propylene, isobutylene, α-octene, α-dodecene, olefins such as α-octadecene, acrylic acid, methacrylic acid, crotonic acid, Unsaturated acids such as maleic acid, maleic anhydride, itaconic acid, etc. or salts or mono- or dialkyl esters thereof, nitriles such as acrylonitrile, methacrylonitrile, amides such as acrylamide, methacrylamide, ethylene sulfonic acid, allyl sulfonic acid. , Olefin sulfonic acids such as methallyl sulfonic acid or salts thereof, alkyl vinyl ethers, N-acrylamidomethyltrimethylammonium chloride, allyltrimethylammonium chloride, dimethylallyl vinyl ketone, N-vinylpyrrolidone, vinyl chloride, vinylidene chloride, polyoxyethylene Polyoxyalkylene (meth)allyl ether such as (meth)allyl ether, polyoxypropylene (meth)allyl ether, polyoxyalkylene (meth)acrylate such as polyoxyethylene (meth)acrylate, polyoxypropylene (meth)acrylate, Polyoxyethylene (meth)acrylamide, polyoxyalkylene (meth)acrylamide such as polyoxypropylene (meth)acrylamide, polyoxyethylene (1-(meth)acrylamide-1,1-dimethylpropyl) ester, polyoxyethylene vinyl ether, Polyoxypropylene vinyl ether, polyoxyethylene allylamine, polyoxypropylene allylamine, polyoxyethylene vinylamine, polyoxypropylene vinylamine, 3-buten-1-ol, 4-penten-1-ol, 5-hexen-1-ol Hydroxy group-containing α-olefins such as and derivatives thereof such as acylated products may be copolymerized.

Examples of the PVA-based resin having a functional group introduced by a post-reaction include those having an acetoacetyl group by the reaction with diketene, those having a polyalkylene oxide group by the reaction with ethylene oxide, and those having a reaction with an epoxy compound or the like. Examples thereof include those having a hydroxyalkyl group or those obtained by reacting an aldehyde compound having various functional groups with a PVA resin.
The amount of modification in the modified PVA-based resin, that is, the content of the constituent units derived from various monomers in the copolymer, or the content of the functional group introduced by the post-reaction, is largely different depending on the modified species. Although it cannot be said, it is usually 0.1 to 20 mol %, and particularly preferably 0.5 to 12 mol %.

In the present invention, among these various modified PVA-based resins, it is preferable to use the PVA-based resin containing a structural unit having a primary hydroxyl group in the side chain. The number of primary hydroxyl groups is usually 1 to 5, preferably 1 to 2, and particularly preferably 1. Further, it is preferable to have a secondary hydroxyl group in addition to the primary hydroxyl group.

The content (modification rate) of the structural unit having a primary hydroxyl group on the side chain in the PVA-based resin containing the structural unit having a primary hydroxyl group on the side chain varies depending on the type of the structural unit, but is usually 0.1. ~ 12 mol%. If the modification rate is too low, the adhesion to the model material tends to decrease, and if the modification rate is too high, the glass transition temperature (Tg) becomes too high and the cooling and solidifying rate becomes too fast, so that the model material The adhesiveness of is likely to decrease.

Examples of the PVA-based resin containing a structural unit having a primary hydroxyl group in its side chain include, for example, a PVA-based resin having a 1,2-diol structural unit in its side chain and a PVA having a hydroxyalkyl group structural unit in its side chain. Examples include resin series. Among them, the side chains are improved in that the affinity with the model material is improved, the adhesion with the model material is improved, and the affinity with the block copolymer (c) described later is excellent. A PVA-based resin having a 1,2-diol structural unit (hereinafter sometimes referred to as "1,2-diol-containing PVA-based resin") is preferable. As the 1,2-diol-containing PVA-based resin, it is particularly preferable to use a PVA-based resin having a 1,2-diol structural unit in the side chain represented by the following general formula (1), because the adhesion with the model material is It is preferable in that it becomes better and the reactivity between the hydroxyl group of the block copolymer (c) described later and the functional group capable of reacting with this hydroxyl group becomes higher.

The content (modification rate) of the 1,2-diol structural unit represented by the general formula (1) in the 1,2-diol-containing PVA-based resin is usually 0.1 to 10 mol %, preferably 0. It is 0.5 to 9 mol %, more preferably 2 to 8.5 mol %, and particularly preferably 5 to 8 mol %. If the modification rate is too low, the reactivity with the functional group of the block copolymer (c) described below tends to decrease, and if it is too high, the crystallization rate becomes too slow and the shape tends to deform during lamination. is there.
The portions other than the 1,2-diol structural unit are a vinyl alcohol structural unit and a vinyl ester structural unit of an unsaponifiable portion, as in a normal PVA-based resin.

All of R ^{1 to} R ³ and R ^{4 to} R ⁶ in the 1,2-diol structural unit represented by the general formula (1) are hydrogen atoms, and the end of the side chain becomes a primary hydroxyl group, and the block copolymerization is further performed. Although it is desirable in that the reactivity with the functional group of the coalescence is improved, it may be substituted with an alkyl group having 1 to 4 carbon atoms as long as the amount is such that the resin characteristics are not significantly impaired. The alkyl group having 1 to 4 carbon atoms is, for example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, or the like, and if necessary, a halogen group or a hydroxyl group. It may have a substituent such as an ester group, a carboxylic acid group and a sulfonic acid group.

Further, X in the 1,2-diol structural unit represented by the general formula (1) is most preferably a single bond from the viewpoint of thermal stability and stability under high temperature and acidic conditions. It may be a binding chain as long as it does not impair the effects of the present invention, such a binding chain, hydrocarbons such as alkylene, alkenylene, alkynylene, phenylene, naphthylene (these hydrocarbons are fluorine, chlorine, bromine, etc. another of may be substituted with halogen, _{etc.), -O -, - (CH} 2 O) m -, - (OCH 2) m -, - (CH 2 O) mCH 2 -, - CO -, - _{COCO -, - CO (CH 2} ) m CO -, - CO (C 6 H 4) CO -, - S -, - CS -, - SO -, - SO 2 -, - NR -, - CONR -, - _{NRCO -, - CSNR -, -} NRCS -, - NRNR -, - HPO 4 -, - Si (OR) 2 -, - OSi (OR) 2 -, - OSi (OR) 2 O -, - Ti (OR) _{2 -, - OTi (OR)} 2 -, - OTi (OR) 2 O -, - Al (OR) -, - OAl (OR) -, - OAl (OR) O-, etc. (R is independently arbitrary And a hydrogen atom or an alkyl group is preferable, and m is an integer of 1 to 5). Of these, an alkylene group having 6 or less carbon atoms, particularly a methylene group, or —CH ₂ OCH ₂ — is preferable from the viewpoint of stability during production or use.

The method for producing the PVA-based resin having a 1,2-diol structure in the side chain is not particularly limited, but (i) a copolymer of a vinyl ester-based monomer and a compound represented by the following general formula (2) is used. A method for saponification, a method for saponifying and decarboxylating a copolymer of (ii) a vinyl ester-based monomer and a compound represented by the following general formula (3), and (iii) a vinyl ester-based monomer and the following general formula A method of saponifying and deketalizing a copolymer with the compound represented by (4) is preferably used, and for example, it can be produced by the method described in paragraphs [0011] to [0019] of JP-A 2004-285143. it can.

The PVA-based resin (a) used in the present invention may be one kind or a mixture of two or more kinds. In that case, the above-mentioned unmodified PVA-based resins and unmodified PVA may be used. -Based resin and PVA-based resin having the structural unit represented by the general formula (1), PVA-based resins having the structural unit represented by the general formula (1) having different saponification degree, polymerization degree, modification degree and the like, An unmodified PVA-based resin or a combination of a PVA-based resin having the structural unit represented by the general formula (1) and another modified PVA-based resin can be used.

[Specific silica (b)]
The specific silica (b) used together with the PVA-based resin (a) is a silica having a physical property of BET specific surface area of 15 to 350 m ² /g. The BET specific surface area is an index showing how many pores the porous silica has, and shows a state of secondary aggregation. Further, the BET specific surface area is a value measured by the nitrogen adsorption BET one-point method, and the measurement procedure conforms to the regulation of JIS Z 8830. The BET specific surface area is preferably 100 to 300 m ² / g, particularly preferably from 150 to 250 ² / g. If the BET specific surface area is too small, the dispersion uniformity in the PVA-based resin (a) will be poor, and if the BET specific surface area is too large, the effect of improving water resistance will be low.

In addition to the BET specific surface area, as another physical property of silica (b), it is preferable that the oil absorption amount is 100 to 500 ml/100 g. The oil absorption amount is a value measured according to JIS K5101-13-1.

Among the specific silica (b), it is preferable to use amorphous silica, particularly wet silica, from the viewpoint of hydrophilicity.

The primary particle diameter of the specific silica (b) is usually 5 to 60 nm, preferably 10 to 30 nm, and particularly preferably 15 to 25 nm. The primary particle size of silica (b) can be measured using a commercially available laser diffraction/scattering type particle size distribution measuring device by taking an arbitrary measurement sample from the population. If the primary particle size is too large, uniform dispersion is difficult and the strength of the support material tends to decrease, and if it is too small, the flexibility of the support material itself tends to be impaired.

Further, in the present invention, among silica (b), those having a hydrophobic surface on the silica surface or non-porous silica have a poor dispersion state in the PVA-based resin (a) and cause non-uniform aggregation. Or, the strength of the molded product tends to be remarkably reduced, which is not preferable.

The content of the specific silica (b), to the P VA resin (a) 100 parts by weight of a 0.1 to 15 parts by weight, more preferably 1 to 10 parts by weight, particularly preferably 2 to 8 parts by weight. The content of the specific silica (b) is 0.1 to 10 wt% der of the total support material is, more preferably 2 to 8% by weight, particularly preferably 3-5 wt%. If the content is too small, it tends to be difficult to impart a sufficiently low hygroscopic effect to the support material, and if the content is too large, the strength of the support material itself decreases and it tends to become brittle. is there.

[Specific block copolymer (c)]
In the present invention, the specific block copolymer (c) can be used together with the PVA-based resin (a) and the specific silica (b) for the purpose of imparting molding stability.

The specific block copolymer (c) has a polymer block of an aromatic vinyl compound represented by styrene as a hard segment, and a polymer block of a conjugated diene compound as a soft segment or a polymer block remaining in the polymer block. It has a block in which some or all of the heavy bonds are hydrogenated, or a polymer block of isobutylene.
Further, as the specific block copolymer (c), one having a functional group capable of reacting with a hydroxyl group in a side chain is used, and specifically, one having a carboxylic acid group or a derivative group thereof is preferably used.

The structure of each block in the block copolymer (c) is such that when the hard segment is represented by X and the soft segment is represented by Y, a diblock copolymer represented by XY, XY- Examples thereof include a triblock copolymer represented by X or Y-XY, and a polyblock copolymer in which X and Y are alternately connected, and the structure thereof is linear, branched, or star-shaped. And so on. Among them, a linear triblock copolymer represented by XYX is preferable in terms of mechanical properties.

Examples of the monomer used for forming the polymer block of the aromatic vinyl compound which is the hard segment include styrene; α-methylstyrene, β-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, Alkyl styrenes such as t-butyl styrene, 2,4-dimethyl styrene and 2,4,6-trimethyl styrene; halogenated styrenes such as monofluoro styrene, difluoro styrene, monochloro styrene, dichloro styrene and methoxy styrene; vinyl naphthalene and vinyl Examples thereof include vinyl compounds having an aromatic ring other than the benzene ring, such as anthracene, indene, and acetonaphthylene, and their derivatives. The polymer block of the aromatic vinyl compound may be a homopolymer block of the above-mentioned monomer or a copolymer block of two or more kinds of plural monomers, and a styrene homopolymer block is preferably used.

The polymer block of the aromatic vinyl compound may be a copolymer of a small amount of a monomer other than the aromatic vinyl compound, as long as the effect of the present invention is not impaired. Examples of such a monomer include butene and pentene. , Olefins such as hexene, diene compounds such as butadiene and isoprene, vinyl ether compounds such as methyl vinyl ether and allyl ether compounds, and the copolymerization ratio thereof is usually 10 mol% or less of the whole polymer block. is there. These monomers may be used alone or in combination of two or more.

The weight average molecular weight of the polymer block of the aromatic vinyl compound in the block copolymer (c) is usually 10,000 to 300,000, particularly 20,000 to 200,000, and further 50,000 to 100. Those of 1,000 are preferably used. The weight average molecular weight is a value obtained by gel permeation chromatography (GPC) using polystyrene as a standard.

Examples of the monomer used for forming the polymer block that is the soft segment include 1,3-butadiene, isoprene (2-methyl-1,3-butadiene), and 2,3-dimethyl-1,3-butadiene. , A conjugated diene compound such as 1,3-pentadiene, and isobutylene, and these may be used alone or in combination of two or more kinds. Of these, homopolymerized blocks or copolymerized blocks of isoprene, butadiene, and isobutylene are preferable, and homopolymerized blocks of butadiene or isobutylene are particularly preferably used.

In the case of such a polymer block of a conjugated diene compound, there are cases in which a plurality of bond types are formed by polymerization. For example, in butadiene, a butadiene unit (—CH ₂ —CH (CH═CH ₂ ) with 1,2-bonds is used. -) and a butadiene unit by 1,4 bonds _{(-CH 2 -CH = CH-CH} 2 -) is generated. The production ratios of these differ depending on the type of the conjugated diene compound, and therefore cannot be generally stated, but in the case of butadiene, the production ratio of 1,2-bonds is usually in the range of 20 to 80 mol %.

In the polymer block made of such a conjugated diene compound, the heat resistance and weather resistance of the styrene-based thermoplastic elastomer can be improved by hydrogenating a part or all of the remaining double bonds. The hydrogenation rate at that time is preferably 50 mol% or more, and particularly preferably 70 mol% or more.
Note that, by such a hydrogenation, for example butadiene unit Butadiene 1,2 bonds, oxybutylene units _{(-CH 2 -CH (CH 2 -CH} 3) -) , and the butadiene units produced by 1,4-bond two consecutive ethylene units _{(-CH 2 -CH 2 -CH 2 -CH} 2 -) a, but it is usually produced in preference former.

In addition, the polymer block which is such a soft segment may be one in which a small amount of a monomer other than the above-mentioned monomers is copolymerized within a range that does not impair the effects of the present invention, and examples of such a monomer include aromatic compounds such as styrene. Examples thereof include vinyl compounds, olefins such as butene, pentene and hexene, vinyl ether compounds such as methyl vinyl ether and allyl ether compounds, and the copolymerization ratio thereof is usually 10 mol% or less of the whole polymer block. These monomers may be used alone or in combination of two or more.

The weight average molecular weight of the conjugated diene compound in the block copolymer (c) or the polymer block derived from isobutylene is usually 10,000 to 300,000, particularly preferably 20,000 to 200, 000, and more preferably 50,000 to 100,000. The weight average molecular weight is a value obtained by gel permeation chromatography (GPC) using polystyrene as a standard.

As described above, in the block copolymer (c) used in the present invention, the hard segment is a polymer block of an aromatic vinyl compound, and the soft segment is a polymer block of a conjugated diene compound, or a residual double bond thereof. It is composed of a polymer block partially or wholly hydrogenated, an isobutylene polymer block, and the like. Typical examples thereof include a styrene/butadiene block copolymer (SBS) made from styrene and butadiene as raw materials. ), a styrene/butadiene/butylene block copolymer (SBBS) in which the side chain double bond in the butadiene structural unit of SBS is hydrogenated, and a styrene/ethylene/butylene block copolymer in which the main chain double bond is hydrogenated. Examples thereof include a polymer (SEBS), a styrene/isoprene block copolymer (SIPS) made from styrene and isoprene, and a styrene/isobutylene block copolymer (SIBS) made from styrene and isobutylene. SEBS and SIBS having excellent properties and weather resistance are preferably used.

The content ratio of the polymer block of the aromatic vinyl compound which is the hard segment and the polymer block which is the soft segment in the block copolymer (c) is usually a weight ratio of hard segment/soft segment=10/ 90 to 70/30, particularly preferably 20/80 to 50/50. If the content ratio of the polymer block of the aromatic vinyl compound is too large or too small, the balance between flexibility and rubber elasticity of the block copolymer may be lost.

The block copolymer (c) is obtained by obtaining a block copolymer having a polymer block of an aromatic vinyl compound and a polymer block of a conjugated diene compound or isobutylene, and further, if necessary, a polymer of the conjugated diene compound. It can be obtained by hydrogenating the double bond in the block.

First, as a method for producing a block copolymer having a polymer block of an aromatic vinyl compound and a conjugated diene compound or a polymer block of isobutylene, a known method can be used, for example, an alkyllithium compound or the like. And an aromatic vinyl compound and a conjugated diene compound or isobutylene are sequentially polymerized in an inert organic solvent.

Next, as a method for hydrogenating a block copolymer having a polymer block of this aromatic vinyl compound and a polymer block of a conjugated diene compound, a known method can be used, for example, a borohydride compound or the like. And a reduction with hydrogen using a metal catalyst such as platinum, palladium, or Raney nickel.

The specific block copolymer (c) used in the present invention has a side chain having a functional group capable of reacting with a hydroxyl group. Such a functional group is particularly preferably a carboxylic acid, and by using a block copolymer having a functional group capable of reacting with a hydroxyl group on the side chain (specific block copolymer (c)), the molding stability is particularly improved. It is possible to obtain an excellent support material.

As the content of the carboxylic acid in the block copolymer (c), the acid value measured by the titration method is usually 0.5 to 20 mg CH ₃ ONa/g, and particularly 1 to 10 mg CH ₃ ONa/g, Those having 1.5 to ₃ mg CH ₃ ONa/g are preferably used.
If the acid value is too low, the effect of introducing a functional group cannot be sufficiently obtained, and if it is too high, the melt viscosity of the support material tends to be too high due to a crosslinking reaction.

As a method for introducing such a functional group containing a carboxylic acid into a block copolymer, a known method can be used. For example, during production of the block copolymer, that is, during copolymerization, α, β- A method of copolymerizing an unsaturated carboxylic acid or a derivative thereof, or a method of adding an α,β-unsaturated carboxylic acid or a derivative thereof after producing a block copolymer is preferably used. Examples of such an addition method include a method of radical reaction in a solution in the presence or absence of a radical initiator, and a method of melt-kneading in an extruder.

Examples of the α,β-unsaturated carboxylic acid or its derivative used for introducing the carboxylic acid group include, for example, α,β-unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid; maleic acid, succinic acid, itaconic acid, Examples thereof include α,β-unsaturated dicarboxylic acids such as phthalic acid; α,β-unsaturated monocarboxylic acid esters such as glycidyl acrylate, glycidyl methacrylate, hydroxyethyl acrylate, and hydroxymethyl methacrylate. The carboxylic acid group introduced into the block copolymer of the present invention may form an acid anhydride structure with an adjacent carboxylic acid group, maleic anhydride, succinic anhydride, itaconic anhydride, Examples thereof include α,β-unsaturated dicarboxylic acid anhydrides such as phthalic anhydride.

The weight average molecular weight of the specific block copolymer (c) is usually 50,000 to 500,000, particularly preferably 120,000 to 450,000, and more preferably 150,000 to 400,000. To be
When the weight average molecular weight is too large or too small, and the melt viscosity described below is too high or too low, the specific block copolymer (c) is uniformly present in the PVA-based resin (a). The dispersed morphology cannot be obtained, and the mechanical properties of the resin tend to deteriorate.
The weight average molecular weight of the block copolymer (c) is a value obtained by using gel permeation chromatography (GPC) with polystyrene as a standard.

The melt viscosity of the block copolymer (c) at 220° C. and a shear rate of 122 sec ⁻¹ is usually 100 to 3000 mPa·s, particularly 300 to 2000 mPa·s, and more preferably 800 to 1500 mPa·s. Used.

Further, in the present invention, as the above-mentioned specific block copolymer (c), one kind may be used, but a plurality of kinds may be appropriately mixed and used for the purpose of obtaining desired characteristics. Is.

Examples of commercially available products of the block copolymer (c) having such a reactive functional group include "Tuftec M series" manufactured by Asahi Kasei Co., which is a carboxyl group-modified product of SEBS, and "f-dynalone" manufactured by JSR. , "Clayton FG" manufactured by Shell Japan Co., Ltd., and the like.

The content of the specific block copolymer (c) is usually preferably 5 to 100 parts by weight, more preferably 10 to 70 parts by weight, based on 100 parts by weight of the PVA-based resin (a). It is particularly preferably 15 to 60 parts by weight. The content of the specific block copolymer (c) is preferably 5 to 50% by weight, more preferably 15 to 45% by weight, and particularly preferably 25 to 40% by weight based on the whole support material. .. If the content is too small, it tends to be difficult to impart molding stability, and the adhesiveness to the model material tends to decrease. If the content is too large, the flexibility of the molded product tends to be too high, and the dimensional stability tends to decrease.

[Support material for additive manufacturing]
The additive manufacturing support material of the present invention comprises a resin composition containing the PVA-based resin (a), the specific silica (b), and more preferably the specific block copolymer (c). However, since the support material is usually formed into a strand shape and supplied and installed in the head part of the additive manufacturing apparatus in a state that it is wound around the reel, it has flexibility and toughness that does not break even when wound around the reel. It may be required, and it is preferable to appropriately mix various additives in practical use. Support material in the present invention, the content of the PVA-based resin (a) is 45 to 95 wt% of the total support material, preferably from 55 to 95% by weight, particularly preferably 60 to 90 wt%. If the content is too small, the water-soluble removability tends to decrease, and if it is too large, the flexibility tends to decrease.

As the above-mentioned additive, for example, a plasticizer may be blended in the support material as in the present invention, but the content of the plasticizer is required to realize improvement in molding stability and low hygroscopicity of the support material. It is preferably small, and is preferably 20% by weight or less, more preferably 10% by weight or less, still more preferably 1% by weight or less, and particularly preferably 0.1% by weight or less based on the whole support material.
Further, the equilibrium moisture absorption rate is usually 0.1 to 40% by weight, and if the equilibrium moisture absorption rate is too large, the water content in the support material tends to be too much, and the molding stability tends to decrease.

Furthermore, as the above-mentioned various additives, for example, known additives such as antioxidants, colorants, antistatic agents, ultraviolet absorbers, lubricants, etc., and thermoplastics other than the specific block copolymer (c) are also included. A resin can be appropriately mixed. Examples of the other thermoplastic resin include various maleic acid-modified thermoplastic resins and polyamide resins from the viewpoint of compatibility.

As in the case of the plasticizer, the content of the various additives is 20% by weight or less, more preferably 10% by weight or less, further 1% by weight or less, and particularly 0.1% by weight or less. It is preferable to have.

The melt viscosity of the additive manufacturing support material of the present invention is preferably 0.2 to 25 g/10 minutes at a melt flow rate (MFR) measured according to JIS K7210 under a load of 2160 g at 210° C., It is particularly preferably 1.0 to 15 g/10 minutes, more preferably 2.0 to 10 g/10 minutes. If the melt viscosity is too low, dripping may occur from the nozzle during shape formation, which may hinder the shape formation, and if it is too high, the nozzle may be clogged.

As a method for producing the support material for layered manufacturing of the present invention, for example, for each of the above components, a predetermined amount is mixed, kneaded in a molten state by heating, extruded in a strand shape, cooled, and wound on a reel. A method of producing a support material applied to additive manufacturing by taking it is mentioned. Specifically, the components are mixed in advance, or they are separately fed to a single-screw or multi-screw extruder, melted and kneaded by heating, and the diameter of 1.5 to 3. It is extruded into a 0 mm strand, cooled and solidified by air cooling or water cooling, and then wound on a reel. The weight of the support material wound on the reel is about 0.5 to 2 kg/piece. The diameter of the strand must be stable, and it has enough flexibility and toughness that it will not break even if it is wound around the reel, and it will not be stiff enough to be delivered to the head without delay during additive manufacturing. is necessary.

[Manufacturing method of layered product, and layered product]
A method of manufacturing a layered product using the layered support material of the present invention will be described.
As the additive manufacturing apparatus used for additive manufacturing, a known one may be used as long as the additive manufacturing apparatus has a plurality of heads capable of respectively extruding a model material and a support material and can perform additive manufacturing by heat melting. For example, Create by Flash Forge A dual-head type additive manufacturing apparatus such as Rayed Enterprise Inc. Eagleed, 3D Systems Inc. MBot Grid II, Stratasys Inc. uPrint SE, or the like can be used. Various resins such as acrylonitrile-butadiene-styrene (ABS) resin, polylactic acid, polystyrene, polyamide, and polyethylene have been studied as the above-mentioned model material for forming a three-dimensional object. However, melt moldability, thermal stability, and after solidification The ABS resin is mainly used because of its mechanical properties, and the support material is required to have excellent adhesion to the ABS resin.

Similar to the support material, the model material is also provided in a state of being formed into a strand and wound on a reel. The strands of the model material and the support material are supplied to separate heads of the additive manufacturing apparatus, are heated and melted by the head portions, and are stacked in a fluid state so as to be pressed onto the stage from separate nozzles. The melting temperature in the head part is usually 150 to 240° C., the composition is extruded at a pressure of 200 to 1000 psi, and the stacking pitch is usually 200 to 350 μm.

As described above, the laminate manufactured from the support material and the model material is cooled and solidified, and then the support material is removed from the above-mentioned laminate to obtain a laminate molded article as a final object. Then, for example, the additive manufacturing support material of the present invention can be dissolved and removed using water. As the method of dissolving and removing, the support material may be dissolved and removed by immersing the laminate in water or warm water contained in a container, or the support material of the laminate may be washed away with running water. Of course, after the support material is peeled off, the remaining portion may be dissolved and removed with water. When the support material is dissolved and removed by immersing the laminate, it is preferable to stir water (warm water) or apply ultrasonic waves to shorten the dissolution and removal time, and the water temperature is preferably about 25 to 80°C. .. When dissolving and removing the support material, about 10 to 10000 times as much water or warm water as the weight of the support material is used. The support material for additive manufacturing of the present invention is also characterized in that it can be easily dissolved and removed even at a relatively low temperature.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the examples, “parts” and “%” mean weight basis unless otherwise specified.

[Example 1]
(I) Production of 1,2-diol-containing PVA-based resin (1) In a reaction can equipped with a reflux condenser, a dropping funnel, and a stirrer, 85 g of vinyl acetate (initially charged 10% of the whole), 460 g of methanol, and Charge 3,3.6-diacetoxy-1-butene 13.6 g (7.2 mol% to charged vinyl acetate), add azobisisobutyronitrile 0.2 mol% (to charged vinyl acetate) and stir. The temperature was raised under a nitrogen stream to start the polymerization. Furthermore, 0.5 hour after the start of polymerization, vinyl acetate (90% of the whole) was added dropwise for 8 hours (dropping rate 95.6 g/hr). Azobisisobutyronitrile was added by 0.1 mol% at 2.5 hours and 4.5 hours after the initiation of polymerization, and m-dinitrobenzene was added at the time when the polymerization rate of vinyl acetate reached 85%. A predetermined amount was added to complete the polymerization, and subsequently, unreacted vinyl acetate monomer was removed out of the system by distillation while blowing in methanol vapor to obtain a methanol solution of the copolymer.

Then, the above solution was diluted with methanol and adjusted to a concentration of 50% and charged in a kneader. While keeping the solution temperature at 35° C., a 2% sodium content methanol solution in sodium hydroxide was added to the vinyl acetate structure in the copolymer. Saponification was carried out by adding the units and the 3,4-diacetoxy-1-butene structural unit at a ratio of 9 mmol per 1 mol of the total amount. As the saponification progressed and the saponified product was deposited and became particles, a 2% methanol solution was further added to 1 mol of the total amount of the vinyl acetate structural unit and the 3,4-diacetoxy-1-butene structural unit. An additional 4 mmol was added for saponification. Then, acetic acid for neutralization was added with 0.8 equivalent of sodium hydroxide, filtered, washed well with methanol, and dried in a hot air dryer to obtain 1,2-diol-containing PVA resin (1). Got

The degree of saponification of the obtained 1,2-diol-containing PVA-based resin (1) depends on the amount of alkali consumption required for hydrolysis of residual vinyl acetate and 3,4-diacetoxy-1-butene structural units in the resin. When analyzed, it was 87 mol %. The average degree of polymerization was 350 when analyzed according to JIS K6726. Then, the melting point was measured by a differential thermal analyzer DSC and found to be 177° C.
The content of the 1,2-diol structural unit represented by the formula (1) is determined by ¹ H-NMR (300 MHz proton NMR, d6-DMSO solution, internal standard substance; tetramethylsilane, 50° C.). It was 3 mol% when calculated from the measured integral value.

(Ii) Production of Support Material 66.5 parts of the 1,2-diol-containing PVA-based resin (1) and silica (NS-P: BET specific surface area 220 m ² /g, primary particle diameter 15 nm manufactured by Tosoh Silica Co., Ltd.) 5 Parts and a styrene/ethylene/butylene block copolymer (SEBS) having a carboxylic acid group as a block copolymer (c) (“Tuftec M1911” manufactured by Asahi Kasei Corporation, acid value 2 mg CH ₃ ONa/g, weight average molecular weight 200,000). ) After dry blending 28.5 parts, this is fed to a twin-screw extruder, melt-kneaded under the following conditions, extruded into a strand having a diameter of 1.75 mm, air-cooled on a belt and wound on a reel, A support material (filament) was obtained. The support materials (filaments) were evaluated as follows (equilibrium moisture absorption rate, shape stability of the shaped article). The results are shown in Table 1 below.

[Manufacturing conditions]
Extruder: Techno Bell 15mmφ L/D=60
Extrusion temperature (° C.): C1/C2/C3/C4/C5/C6/C7/C8/D=150/170/180/190/200/210/220/220/220
Rotation speed: 200 rpm
Discharge rate: 1.5 kg/hour

(Iii) Evaluation of support material [equilibrium moisture absorption rate]
The support material (filament) was cut into a length of 2 mm (about 3 g), placed in an aluminum cup and left in an atmosphere of 50° C.×90% RH, and the weight increase was measured with time. Then, the moisture absorption rate when the weight change disappeared and the weight became constant was measured.

[Shape stability of shaped objects]
The support material (filament) obtained above was set in a 3D printer (FDM-200HW-X manufactured by Ninjabot), and a cube having a length of 2 cm, a width of 2 cm, and a height of 2 cm was formed. The angle and the length of one side (total of 4 places) of the obtained cube were measured and evaluated according to the following criteria.
<Pass range>
Angle: 90°±1°
One side (length, width, height in each height): 2 cm ± 0.5 mm
<Evaluation criteria>
A: All four locations meet the pass range.
B: 3 places meet the pass range.
C: Two places meet the pass range.
D: Only one place meets the pass range.

[Example 2]
(I) Production of 1,2-diol-containing PVA-based resin (2) In a reaction can equipped with a reflux condenser, a dropping funnel, and a stirrer, 85 g of vinyl acetate (initially charged 10% of the whole), 460 g of methanol, and Charge 3,3.6-diacetoxy-1-butene 13.6 g (7.2 mol% to charged vinyl acetate), add azobisisobutyronitrile 0.2 mol% (to charged vinyl acetate) and stir. The temperature was raised under a nitrogen stream to start the polymerization. Furthermore, 0.5 hour after the initiation of the polymerization, vinyl acetate (90% of the whole) was added dropwise for 8 hours (dropping rate 95.6 g/hr). Azobisisobutyronitrile was added by 0.1 mol% at 2.5 hours and 4.5 hours after the initiation of polymerization, and m-dinitrobenzene was added at the time when the polymerization rate of vinyl acetate reached 85%. A predetermined amount was added to complete the polymerization, and subsequently, unreacted vinyl acetate monomer was removed out of the system by distillation while blowing in methanol vapor to obtain a methanol solution of the copolymer.

Then, the above solution was diluted with methanol and adjusted to a concentration of 50% and charged in a kneader. While keeping the solution temperature at 35° C., a 2% sodium content methanol solution in sodium hydroxide was added to the vinyl acetate structure in the copolymer. Saponification was carried out by adding the units and the 3,4-diacetoxy-1-butene structural unit at a ratio of 9 mmol per 1 mol of the total amount. As the saponification progressed and the saponified product was deposited and became particles, a 2% methanol solution was further added to 1 mol of the total amount of the vinyl acetate structural unit and the 3,4-diacetoxy-1-butene structural unit. An additional 4 mmol was added for saponification. Then, acetic acid for neutralization was added with 0.8 equivalent of sodium hydroxide, filtered off, washed well with methanol and dried in a hot air drier to obtain 1,2-diol-containing PVA resin (2). Got

The degree of saponification of the obtained 1,2-diol-containing PVA-based resin (2) depends on the amount of alkali consumed for hydrolysis of residual vinyl acetate and 3,4-diacetoxy-1-butene structural units in the resin. When analyzed, it was 99 mol %. The average degree of polymerization was 390 when analyzed in accordance with JIS K6726. Then, the melting point was measured by a differential thermal analyzer DSC, and it was 184° C. The content of the 1,2-diol structural unit represented by the formula (1) is determined by ¹ H-NMR (300 MHz proton NMR, d6-DMSO solution, internal standard substance; tetramethylsilane, 50° C.). It was 7.2 mol% as calculated from the measured integral value.

(Ii) Production of Support Material 66.5 parts of the 1,2-diol-containing PVA-based resin (2) and silica (NS-P:BET specific surface area 220 m ² /g, primary particle diameter 15 nm manufactured by Tosoh Silica Co., Ltd.) 5 And 28.5 parts of a styrene/ethylene/butylene block copolymer (SEBS) having a carboxylic acid group as a block copolymer (c) (“Tuftec M1911” manufactured by Asahi Kasei Co., acid value 2 mg CH ₃ ONa/g). After dry-blending, this was fed to a twin-screw extruder, melt-kneaded under the same conditions as in Example 1 above, extruded into a strand having a diameter of 1.75 mm, air-cooled on a belt, wound on a reel, and supported. A material (filament) was obtained. The support material (filament) was evaluated in the same manner as in Example 1 above (equilibrium moisture absorption rate, shape stability of the shaped article). The results are shown in Table 1 below.

[Example 3]
(Ii) Production of Support Material 95 parts of 1,2-diol-containing PVA-based resin (2) produced in Example 2 and silica (NS-P: Tosoh Silica NS-P:BET specific surface area 220 m ² /g, primary particle diameter) (15 nm) 5 parts after dry blending, this was fed to a twin-screw extruder, melt-kneaded under the same conditions as in Example 1 above, extruded into a strand having a diameter of 1.75 mm, air-cooled on a belt, and reeled. The support material (filament) was taken up. The support material (filament) was evaluated in the same manner as in Example 1 above (equilibrium moisture absorption rate, shape stability of the shaped article). The results are shown in Table 1 below.

[Example 4]
(Ii) Production of Support Material 69.9 parts of 1,2-diol-containing PVA-based resin (2) produced in Example 2 and silica (NS-P: BET specific surface area 220 m ² /g, manufactured by Tosoh Silica Co., Ltd., primary) Styrene/ethylene/butylene block copolymer (SEBS) having a carboxylic acid group as a block copolymer (c) (0.1 part, particle diameter 15 nm) (“Tuftec M1911” manufactured by Asahi Kasei Corporation, acid value 2 mg CH ₃ ONa/ g) After dry blending 29.9 parts, this was fed to a twin-screw extruder, melt-kneaded under the same conditions as in Example 1 above, extruded into a strand having a diameter of 1.75 mm, and air-cooled on a belt. Then, it was wound on a reel to obtain a support material (filament). The support material (filament) was evaluated in the same manner as in Example 1 above (equilibrium moisture absorption rate, shape stability of the shaped article). The results are shown in Table 1 below.

[Example 5]
(Ii) Production of Support Material 63 parts of 1,2-diol-containing PVA-based resin (2) produced in Example 2 and silica (NS-P: Tosoh Silica NS-P:BET specific surface area 220 m ² /g, primary particle diameter) 15 nm) 10 parts and 27 parts of a styrene/ethylene/butylene block copolymer (SEBS) having a carboxylic acid group as a block copolymer (c) (“Tuftec M1911” manufactured by Asahi Kasei Corporation, acid value 2 mg CH ₃ ONa/g). Was dry-blended, fed to a twin-screw extruder, melt-kneaded under the same conditions as in Example 1 above, extruded into a strand having a diameter of 1.75 mm, air-cooled on a belt and wound on a reel, A support material (filament) was obtained. The support material (filament) was evaluated in the same manner as in Example 1 above (equilibrium moisture absorption rate, shape stability of the shaped article). The results are shown in Table 1 below.

[Example 6]
(Ii) Production of Support Material 85.5 parts of 1,2-diol-containing PVA-based resin (2) produced in Example 2 and silica (NS-P:BET specific surface area 220 m ² /g, manufactured by Tosoh Silica Co., Ltd., primary) Styrene/ethylene/butylene block copolymer (SEBS) having 5 parts of a particle diameter of 15 nm) and a carboxylic acid group as a block copolymer (c) (“Tuftec M1911” manufactured by Asahi Kasei Corporation, acid value 2 mg CH ₃ ONa/g) After dry blending 9.5 parts, this was fed to a twin-screw extruder, melt-kneaded under the same conditions as in Example 1 above, extruded into a strand having a diameter of 1.75 mm, air-cooled on a belt, and reeled. The support material (filament) was taken up. The support material (filament) was evaluated in the same manner as in Example 1 above (equilibrium moisture absorption rate, shape stability of the shaped article). The results are shown in Table 1 below.

[Example 7]
(Ii) Production of Support Material 57 parts of 1,2-diol-containing PVA-based resin (2) produced in Example 2 and silica (NS-P: Tosoh Silica NS-P:BET specific surface area 220 m ² /g, primary particle diameter) 15 nm) and 38 parts of a styrene/ethylene/butylene block copolymer (SEBS) having a carboxylic acid group as a block copolymer (c) (“Tuftec M1911” manufactured by Asahi Kasei Corporation, acid value 2 mg CH ₃ ONa/g). Was dry-blended, fed to a twin-screw extruder, melt-kneaded under the same conditions as in Example 1 above, extruded into a strand having a diameter of 1.75 mm, air-cooled on a belt and wound on a reel, A support material (filament) was obtained. The support material (filament) was evaluated in the same manner as in Example 1 above (equilibrium moisture absorption rate, shape stability of the shaped article). The results are shown in Table 1 below.

[Example 8]
(Ii) Production of Support Material 66.5 parts of 1,2-diol-containing PVA resin (2) produced in Example 2 and silica (E-220A manufactured by Tosoh Silica Corporation: BET specific surface area 160 m ² /g, primary) Styrene/ethylene/butylene block copolymer (SEBS) having a carboxylic acid group as a block copolymer (c) (SEA) (“Tuftec M1911” manufactured by Asahi Kasei Corporation, acid value 2 mg CH3ONa/g). After dry-blending 5 parts, this was fed to a twin-screw extruder, melt-kneaded under the same conditions as in Example 1 above, extruded into a strand having a diameter of 1.75 mm, air-cooled on a belt, and wound on a reel. Then, a support material (filament) was obtained. The support material (filament) was evaluated in the same manner as in Example 1 above (equilibrium moisture absorption rate, shape stability of the shaped article). The results are shown in Table 1 below.

[Example 9]
(Ii) Manufacture of Support Material 66.5 parts of 1,2-diol-containing PVA-based resin (2) prepared in Example 2 and silica (AZ204 manufactured by Tosoh Silica Corporation: BET specific surface area 250 m ² /g, primary particle diameter) 17 parts) and 5 parts of styrene/ethylene/butylene block copolymer (SEBS) having a carboxylic acid group as the block copolymer (c) (“Tuftec M1911” manufactured by Asahi Kasei Corporation, acid value 2 mg CH ₃ ONa/g) 28. After dry-blending 5 parts, this was fed to a twin-screw extruder, melt-kneaded under the same conditions as in Example 1 above, extruded into a strand having a diameter of 1.75 mm, air-cooled on a belt, and wound on a reel. Then, a support material (filament) was obtained. The support material (filament) was evaluated in the same manner as in Example 1 above (equilibrium moisture absorption rate, shape stability of the shaped article). The results are shown in Table 1 below.

[Comparative Example 1]
(I) Production of PVA-based resin In a reaction vessel equipped with a reflux condenser, a dropping funnel, and a stirrer, 100 parts of vinyl acetate and 100 parts of methanol were charged, and 0.15 mol% of azobisisobutyronitrile (pair charge) (Vinyl acetate) was added, and the temperature was raised under a nitrogen stream while stirring to start polymerization. Further, after 5 hours from the initiation of polymerization, 0.05 mol% of azobisisobutyronitrile was added, and when the polymerization rate of vinyl acetate reached 85%, a predetermined amount of m-dinitrobenzene was added to terminate the polymerization. Then, the unreacted vinyl acetate monomer was removed out of the system by distillation while blowing methanol vapor to obtain a methanol solution of the copolymer.

Then, the above solution was diluted with methanol and adjusted to a concentration of 50% and charged in a kneader. While maintaining the solution temperature at 35° C., a methanol solution of sodium hydroxide having a sodium content concentration of 2% was added to acetic acid in the copolymer. Saponification was carried out by adding sodium hydroxide at a ratio of 4.3 mmol to 1 mol of vinyl structural unit. As the saponification progressed and the saponified product precipitated and became particulate, 1.0 equivalent of sodium hydroxide to which acetic acid for neutralization was added was added, filtered and washed thoroughly with methanol. It was dried in a hot air dryer to obtain a PVA resin.

The saponification degree of the obtained PVA-based resin was 88 mol% when analyzed by the amount of alkali consumption required for residual vinyl acetate. The average degree of polymerization was 500 when analyzed in accordance with JIS K6726.

(Ii) Production of Support Material 100 parts of the PVA-based resin was supplied to a twin-screw extruder, melt-kneaded under the same conditions as in Example 1 above, extruded into a strand having a diameter of 1.75 mm, and air-cooled on a belt. Then, it was wound on a reel to obtain a support material (filament). The support material (filament) was evaluated in the same manner as in Example 1 above (equilibrium moisture absorption rate, shape stability of the shaped article). The results are shown in Table 1 below.

[Comparative Example 2]
A support material (filament) was prepared in the same manner as in Comparative Example 1 except that the 1,2-diol-containing PVA resin (2) produced in Example 2 was used instead of the PVA resin produced in Comparative Example 1. It was made. The support material (filament) was evaluated in the same manner as in Example 1 above (equilibrium moisture absorption rate, shape stability of the shaped article). The results are shown in Table 1 below.

As is clear from the above results, the example product containing the PVA-based resin (a) and the specific silica (b) has an equilibrium moisture absorption rate of 40% or less, and is excellent in low hygroscopicity. Recognize. In addition, good results were obtained regarding the evaluation of the shape stability of the molded article. In particular, the products of Examples 1, 2, 4, 5, 7, 8, 9 containing the specific block copolymer (c) in addition to the PVA-based resin (a) and the specific silica (b) are It can be seen that the equilibrium moisture absorption rate was 30% or less, and that the one having further excellent low hygroscopicity was obtained. On the other hand, the comparative example products which did not use the specific silica (b) had a high equilibrium moisture absorption rate of more than 40%. In addition, the evaluation of the shape stability of the modeled product was inferior to that of the example.

The support material for layered modeling of the present invention is excellent in low hygroscopicity, and can be suitably used as a support material at the time of modeling by the hot melt lamination method.

Claims (6)

Contains a polyvinyl alcohol-based resin (a) and silica (b) having a BET specific surface area of 15 to 350 m ² /g ,
The content of silica (b) is 0.1 to 15 parts by weight with respect to 100 parts by weight of the polyvinyl alcohol resin (a),
The content of the polyvinyl alcohol resin (a) is 45 to 95% by weight of the whole support material,
The content of the silica (b) is layered manufacturing for support material, wherein from 0.1 to 10 wt% der Rukoto the overall support material. Further, it contains a block copolymer (c) having at least one of a polymer block of an aromatic vinyl compound, a polymer block of a conjugated diene compound and its hydrogenated block, and further having a functional group capable of reacting with a hydroxyl group. layered manufacturing for support material according to claim 1 Symbol mounting characterized. The content of the block copolymer (c) is 5 to 100 parts by weight relative to 100 parts by weight of the polyvinyl alcohol resin (a), and the support material for layered manufacturing according to claim 1 or 2. .. The polyvinyl alcohol-based resin (a) is a polyvinyl alcohol-based resin containing a structural unit having a primary hydroxyl group in a side chain, and the support material for layered manufacturing according to any one of claims 1 to 5 , wherein .. The support material for layered manufacturing according to claim 4 , wherein the structural unit having a primary hydroxyl group in its side chain is a structural unit having a 1,2-diol structure in its side chain. A laminate-molded article characterized by sequentially stacking the additive manufacturing support material according to any one of claims 1 to 6 and a model material in a fluidized state, solidifying, and then removing the support material. Production method.