JP2015205994A - Polylactic acid base resin for thermofusion type road-marking coating material and thermofusion type road-marking coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polylactic acid base resin for a thermofusion type road-marking coating material in which a balance between molecular weight and melt viscosity is satisfactory, and achieving the coexistence of the coating suitability and coating film strength in a thermofusion type coating material.SOLUTION: Provided is a polylactic acid base resin for a thermofusion type road-marking coating material characterized in that number average molecular weight lies in the range of 25,000 to 50,000, a ratio between L-lactic acid residue and D-lactic acid residue, (L/D) lies in the range of 90/10 to 50/50, and the main component of the D-lactic acid residue being D-lactic acid residue derived from mesolactide.

Description

The present invention relates to a polylactic acid-based resin for a heat-melting road display paint that achieves a low melt viscosity by using an amorphous polylactic acid resin made of meso-lactide (M-lactide), and the polylactic acid-based resin. The present invention relates to a heat melting type road marking paint composition using a resin.

Due to the recent increase in awareness of environmental problems, road marking paints are shifting from solvent-based paints to hot-melt paints.

  Hot melt type road marking paints are generally composed of binder resin, color pigment, filler, plasticizer, wax, stabilizer, antioxidant, glass beads, etc. Still use petroleum-based resin.

  For example, Patent Document 1 and Patent Document 2 disclose the use of petroleum resins such as C5 fraction and C9 fraction as the binder resin. Patent Document 3 discloses the use of a methacrylate resin as a spray resin-based application. Since these all use resin made from petroleum, there is no environmental protection effect, and there has been a demand for conversion to materials with less environmental impact.

  In Patent Document 4, a polylactic acid resin having a weight average molecular weight of 50,000 and a ratio of L-lactic acid to D-lactic acid (L / D) in the range of 5/95 to 95/5 is bound. Inventions relating to hot melt paints used as agents are disclosed, but these polylactic acid resins polymerized from L-lactide and D-lactide have a high melt viscosity and cannot be processed with good coating properties. There was a problem that the nature was bad.

Japanese Patent No. 4350963 JP 2005-15597 A International Publication No. 2008/022861 JP 2013-173925 A

  An object of the present invention is to provide a polylactic acid-based resin for a heat-melting road marking paint having a good balance between molecular weight and melt viscosity that realizes both coating suitability and coating strength of the heat-melting paint.

  As a result of intensive studies, the present inventors have a number average molecular weight in the range of 25,000 to 50,000, and the ratio of L-lactic acid to D-lactic acid (L / D) is 90/10 to 50/50. Amorphous polylactic acid resin (A) characterized in that D-lactic acid is mainly derived from meso lactide, and is composed of L-lactide and D-lactide having the same molecular weight. The present invention was completed by finding that it has a low melt viscosity as compared with the polylactic acid resin and has good coating suitability as a hot melt type road marking paint.

That is, the present invention is as follows.
(1) The number average molecular weight is in the range of 25,000 to 50,000, and the ratio of L-lactic acid residue to D-lactic acid residue (L / D) is in the range of 90/10 to 50/50. A polylactic acid-based resin for heat-melting road marking paints, wherein the main component of the D-lactic acid residue is a D-lactic acid residue derived from meso lactide.
(2) A hot-melt road marking paint composition comprising the polylactic acid resin (A) according to claim 1 and a colorant (B).

  According to the present invention, as described below, by using a polylactic acid resin having a low melt viscosity, it is possible to provide a hot-melt road paint composition having good coating suitability and low environmental load.

  The polylactic acid-based resin used in the present invention is a polymer containing L-lactic acid and / or D-lactic acid as a main constituent component, but may contain other copolymerization components other than lactic acid. Here, “to be a main constituent” means to occupy 50% by weight or more, preferably 65% by weight or more, more preferably 80% by weight or more, and particularly preferably 100% by weight. Examples of such other copolymer component units include polycarboxylic acids, alcohols, polyhydric alcohols, hydroxycarboxylic acids, lactones, and the like. Specifically, oxalic acid, malonic acid, succinic acid, glutaric acid, Polycarboxylic acids such as adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, fumaric acid, cyclohexanedicarboxylic acid, alcohols such as methanol, ethanol, propanol, butanol, pentanol, hexanol, octanol, decanol, ethylene glycol, Propylene glycol, butanediol, heptanediol, hexanediol, octanediol, nanondiol, decanediol, 1,4-cyclohexanedimethanol, neopentylglycol, glycerin, pentaerythritol, diethyl Polyhydric alcohols such as ethylene glycol, triethylene glycol, polyethylene glycol and polypropylene glycol, carboxylic acids such as glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid and 6-hydroxycaproic acid, glycolide, Examples thereof include units produced from lactones such as ε-caprolactone, β-propiolactone, δ-butyrolactone, β-butyrolactone, γ-butyrolactone, and δ-allerolactone. Such copolymer units are preferably less than 5% by weight, more preferably less than 2% by weight.

In the present invention, the ratio (L / D) of the L-lactic acid residue to the D-lactic acid residue constituting the polylactic acid may be in the range of 10/90 to 50/50 considering the flexibility of the coating film. Preferably, in order to obtain a resin melt viscosity excellent in processability, it is necessary that the main component of the D-lactic acid residue is M-lactide. Here, the “main component” means that the D-lactic acid residue constituting the polylactic acid occupies 50% by weight or more, preferably 65% by weight or more, more preferably 80% by weight or more, and particularly preferably 100%. It occupies mass%.
The melt viscosity at 180 ° C. of the polylactic acid resin of the present invention needs to be in the range of 20 dPa · s to 250 dPa · s, preferably 30 dPa · s to 200 dPa · s, more preferably 40 dPa · s to 180 dPa · s. It is the range of s.

In the present invention, as a polymerization method of the polylactic acid-based resin, for example, a known method for ring-opening polymerization of lactide using a hydroxyl group-containing compound as an initiator can be used.
In the production of the polylactic acid-based resin, M-lactide is used as an essential component, but L-lactide and D-lactide may be used in an amount within the above-mentioned range. As M-lactide, it is preferable from the viewpoint of economic rationality that L-lactic acid is racemized in the process of obtaining L-lactide and is by-produced.
There is no restriction | limiting in particular as said hydroxyl-containing compound used as said initiator, According to the objective, it can select suitably, For example, an aliphatic polyol, hydroxycarboxylic acid, polyester polyol etc. are mentioned.
Examples of the aliphatic polyol include ethylene glycol, glycerin, pentaerythritol and the like.
Examples of the hydroxycarboxylic acid include glycolic acid, lactic acid, and glyceric acid.
Examples of the polyester polyol include polyester polyols obtained from succinic acid, adipic acid, and the like, butanediol, hexanediol, and the like.
Among these, the hydroxyl group-containing compound is preferably ethylene glycol from the viewpoint of versatility. When a diol such as ethylene glycol is used as the hydroxyl group-containing compound, a lactide ring-opening polymer having hydroxyl groups at both ends can be obtained.

In the ring-opening polycondensation, a catalyst may be used. Examples of the catalyst include tin compounds such as tin octylate, organic titanium compounds, and organic tin halide compounds. The usage-amount of the said catalyst in the said ring-opening polycondensation is 100 ppm-1,000 ppm with respect to a monomer, for example.
Examples of the polymerization temperature for the ring-opening polycondensation include 150 ° C to 200 ° C.
Examples of the ring-opening polycondensation time include 1 to 6 hours.
The ring-opening polycondensation is preferably performed in an inert gas atmosphere such as nitrogen gas.

  In the present invention, the molecular weight of the polylactic acid-based resin needs to be 50,000 or less as the number average molecular weight from the viewpoint of melt viscosity. However, if the molecular weight is too low, the strength of the coating film is insufficient, so that it is necessary to be 25,000 or more. More preferably, it is in the range of 30,000 to 45,000. The weight average molecular weight here is a weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC) using chloroform as a solvent.

  The polylactic acid-based resin of the present invention has an L-lactic acid residue to D-lactic acid residue ratio (L / D) within the above range, and the main component of the D lactic acid residue is M-lactide. Moreover, when the molecular weight is within the above range, it is possible to exhibit excellent coating suitability when used in a hot melt type road marking paint and to obtain a practical coating strength.

  The hot melt type road marking paint composition of the present invention contains a colorant (B) together with the above-mentioned polylactic acid resin (A). The colorant (B) is not particularly limited, and generally used inorganic pigments and organic pigments can be used. Examples of inorganic pigments include titanium dioxide, zinc white, lithopone, titanium yellow, white lead, red lead, yellow lead, heat-resistant yellow lead, zinc sulfide, zinc oxide, barium sulfide, and iron oxide. Carbon black, titanium black, acetylene black, lamp black, etc., and organic pigments include condensed azo, disazo, monoazo, diketopyrrolopyrrole, isoindolinone, anthraquinone, heterocyclic, quinacridone Thioindico, perinone, perylene, dioxazine, phthalocyanine and the like, but not limited thereto.

  The average primary particle size of the colorant is not particularly limited, but is preferably in the range of 0.1 to 10 μm from the color developability of the paint. If the average primary particle size is less than 0.1 μm, it is difficult to scatter light. If it exceeds 10 μm, the dispersibility in the paint becomes insufficient, so that the storage stability of the paint when blended in a large amount is deteriorated.

  0.1-30 weight part is preferable with respect to 100 weight part of polylactic acid-type resin (A), and, as for the compounding quantity of a coloring agent (B), 1-20 weight part is more preferable. If the blending amount of the color pigment is within this range, the road marking paint has good visibility both daytime and nighttime. If it is less than 0.1 part by weight, the colorability is poor, and if it exceeds 30 parts by weight, the fluidity of the paint is lowered, so that the workability is deteriorated and the surface appearance and the coating film adhesion are lowered.

  The coating material of the present invention may contain a reflecting material, and is not particularly limited. Examples of materials that actively reflect light include glass beads, mica pieces, aluminum powder, and aluminum flakes. Beads are used. The particle size of the glass beads is preferably 0.1 to 3 mm, more preferably 1 to 2 mm. If the particle size is within this range, the visibility is excellent. The particle diameter here is a value measured by a commonly used Coulter counter method. Further, glass cullet (particle size of about 0.1 to 3 mm) may be mixed for the purpose of improving visibility.

  The amount of the reflective material is preferably 1 to 50 parts by weight, more preferably 10 to 40 parts by weight with respect to 100 parts by weight of the polylactic acid resin (A). If the blending amount is within this range, the construction is easy and the visibility at night is excellent. If it is less than 1 part by weight, the visibility at night is low, and if it exceeds 50 parts by weight, the fluidity of the paint is lowered, so that the workability is deteriorated.

  You may further mix | blend a filler with the hot-melt-type road marking coating composition of this invention. As the filler used in the present invention, a silicate mineral, a silicate mineral, and various minerals that are pulverized by processing such as pulverization are preferably used. Specific examples include bentonite, dolomite, barlite, finely divided silicate, aluminum silicate, silicon oxide, dosonite, shirasu balloon, clay, sericite, feldspar powder, zeolite, talc, mica, calcium carbonate, glass flakes, hydrotalc Sites, silica and the like are mentioned, and among them, calcium carbonate is preferable. The average particle diameter of the filler is preferably 100 μm or less, more preferably 50 μm or less, from the viewpoint of appearance. The average particle diameter here is a value obtained from measurement of the specific surface area by the air permeation method.

The hot-melt road marking coating composition of the present invention may further contain a plasticizer, but it is preferable not to use a plasticizer in consideration of film properties. Examples of the plasticizer that can be used in the present invention include polyester plasticizers, glycerin plasticizers, polycarboxylic acid ester plasticizers, polyalkylene glycol plasticizers, and epoxy plasticizers.
The blending amount of the plasticizer is preferably 10 parts by weight or less, more preferably 5 parts by weight or less with respect to 100 parts by weight of the polylactic acid resin.

  The hot melt type road marking coating composition of the present invention may further contain a carboxyl group reactive end-blocking agent. The carboxyl group-reactive terminal blocking agent is not particularly limited as long as it is a compound capable of blocking the carboxyl terminal group of the polymer, and those used as a blocking agent for the carboxyl terminal of the polymer can be used. In the present invention, the carboxyl group-reactive end-blocking agent not only blocks the end of the polylactic acid resin but also blocks the carboxyl group of acidic low-molecular compounds such as lactic acid produced by thermal decomposition or hydrolysis of the polylactic acid resin. can do. Further, the end-capping agent is more preferably a compound that can also block the hydroxyl end where an acidic low molecular weight compound is generated by thermal decomposition.

  As such a carboxyl group-reactive end-capping agent, it is preferable to use at least one compound selected from an epoxy compound, an oxazoline compound, and a carbodiimide compound, and carbodiimide is particularly preferable.

  Examples of the epoxy compound in the present invention include diphenylcarbodiimide, dicyclohexylcarbodiimide, di-2,6-dimethylphenylcarbodiimide, diisopropylcarbodiimide, dioctyldecylcarbodiimide, di-o-toluylcarbodiimide, di-p-toluylcarbodiimide, di-p-nitro. Phenylcarbodiimide, di-p-aminophenylcarbodiimide, di-p-hydroxyphenylcarbodiimide, di-p-chlorophenylcarbodiimide, di-2,5-dichlorophenylcarbodiimide, p-phenylene-bis-0-toluylcarbodiimide, p -Phenylene-bis-dicyclohexylcarbodiimide, ethylene-bis-diphenylcarbodiimide, ethylene-bis-cyclohexylcarbodiimide, N, N- -0- tolyl carbodiimide, N, N-di - phenyl carbodiimide, N, N-dioctyl decyl carbodiimide, N, N-di-2,6-but-dimethylphenyl carbodiimide, and the like, the use of aliphatic carbodiimides are preferred.

  Further, for the hot melt type road marking paint composition of the present invention, a caking resin other than polylactic acid resin, inorganic fibers, organic fibers, phosphorescent pigments, fluorescent pigments, noctilucents, as long as the object of the present invention is not impaired. You may mix | blend a pigment, a fluid improvement agent, etc.

  Usually, the hot melt type road marking paint composition is melt-mixed at 170 to 210 ° C. using a hot melt mixing device such as a heating kneader. When the melt is applied to the road surface, the melt is applied on the road in a molten state using a smooth display / division line construction machine. In construction, the surface of the road can be pretreated.

  The present invention will be described in more detail below by way of examples, but these examples do not limit the present invention.

(Polylactic acid resin polymerization example 1)
1000 parts of M-lactide, 1.6 parts of ethylene glycol, and 0.28 parts of tin octylate were charged into a four-necked flask, dried in a nitrogen atmosphere, and then heated to 180 ° C. to perform ring-opening polymerization for 2 hours.
Thereafter, 0.20 part of polyphosphoric acid was added as a catalyst deactivator, and after stirring, the remaining monomer was reduced by a reduced pressure treatment. Table 1 shows the measurement results of the number average molecular weight and the melt viscosity at 180 ° C. of the obtained polylactic acid resin (1) by GPC measurement.

(Polylactic acid resin polymerization example 2)
After polymerization of 600 parts of L-lactide, 400 parts of M-lactide, 1.6 parts of ethylene glycol, and 0.28 part of tin octylate in the same manner as in Polymerization Example 1, the residual monomer was reduced in the same manner, Table 1 shows the measurement results of the GPC molecular weight and melt viscosity of the obtained polylactic acid resin (2).

(Polylactic acid polymerization example 3)
After polymerization of 800 parts of L-lactide, 200 parts of D-lactide, 1.6 parts of ethylene glycol, and 0.28 parts of tin octylate in the same manner as in Polymerization Example 1, the residual monomer was reduced in the same manner, Table 1 shows the measurement results of GPC molecular weight and melt viscosity of the obtained polylactic acid resin (3).

(Polylactic acid polymerization example 4)
1000 parts of M-lactide, 0.6 parts of ethylene glycol, and 0.28 parts of tin octylate were charged into a four-necked flask, dried in a nitrogen atmosphere, and then heated to 180 ° C. to perform ring-opening polymerization for 2 hours.
Thereafter, 0.20 part of polyphosphoric acid was added as a catalyst deactivator, and after stirring, the remaining monomer was reduced by a reduced pressure treatment. Table 1 shows the measurement results of the number average molecular weight and the melt viscosity at 180 ° C. of the obtained polylactic acid resin (4) by GPC measurement.

The measurement conditions of GPC used in the present invention are as follows.
Sample concentration: 0.5% by weight
・ Carrier: Tetrahydrofuran ・ Equipment: Alliance HPLC system manufactured by Waters ・ Measurement temperature: 30 ° C.
・ Molecular weight standard sample: Polystyrene standard substance

The melt viscosity measuring apparatus and conditions used in the present invention are as follows. (Manufactured by Shimadzu Corporation, CFT-500C)
-Test mode: constant temperature method-Sample temperature: 180 ° C
・ Remaining heat time: 120s
Test weight: 10.0 kgf / cm2
・ Die hole diameter: 1.00mm
・ Die length: 10.0mm
・ Number of tests: 3 times

(Coating composition example 1)
100 parts by weight of a polylactic acid resin (1) and a colorant (“PEIKE CR-60” manufactured by Ishihara Sangyo:
A coating composition example 1 was obtained by melting and mixing 20 parts by weight of a rutile type titanium oxide average particle size of 0.25 μm) at 180 ° C. with a heating kneader.
The obtained coating composition example 1 was applied onto an asphalt surface at 180 ° C. at a construction speed of 0.8 km / hr and the coating property was visually evaluated. The coating film was uniform and had no defects in appearance. The coatability was good.

(Coating composition example 2)
100 parts by weight of a polylactic acid resin (3) and a colorant (“PEIKE CR-60” manufactured by Ishihara Sangyo:
A coating composition example 2 was obtained by melting and mixing 20 parts by weight of a rutile-type titanium oxide average particle size of 0.25 μm at 180 ° C. with a heating kneader.
When the obtained coating composition example 2 was applied on an asphalt surface at 180 ° C. at a construction speed of 0.8 km / hr and the coating property was visually evaluated, the coating film was uneven and had defects such as faintness. It occurred and the coatability was poor.

  As is clear from the results of Table 1 and the paint composition examples, the polylactic acid resin using M-lactide is relatively the same in molecular weight as the conventional polylactic acid resin not using M-lactide. It is clear that the melt viscosity is low, and it is a very effective means when using a polylactic acid resin, particularly in the field of coating by heating and melting, such as a hot melt paint for roads.

  The hot melt paint composition for roads according to the present invention has a special molecular structure mainly composed of M-lactide, so that the melt viscosity is higher than that of a hot melt paint composition using a conventional polylactic acid resin. It was reduced and good workability could be expressed.

Claims (2)

  The number average molecular weight is in the range of 25,000 to 50,000, the ratio of L-lactic acid residue to D-lactic acid residue (L / D) is in the range of 90/10 to 50/50, A polylactic acid-based resin for a hot-melt type road marking paint, wherein the main component of the D-lactic acid residue is a D-lactic acid residue derived from meso lactide.   A hot-melt road marking paint composition comprising the polylactic acid resin (A) according to claim 1 and a colorant (B).