JPH0859861A - Method and product of surface modification of polyacetal resin substrate - Google Patents

Abstract

PURPOSE: To surface-modify a substrate prepared by molding a specified polyacetal resin composition to produce a surface-modified product improved in adhesion of printed coating film and coatability. CONSTITUTION: A polyacetal resin having a melt flow rate (at 190 deg.C under a load of 2160g) of 1.0-10 is mixed with 1-40wt.% aliphatic polyether resin comprising 75-93mol%, based on the repeating alkylene oxide units, repeating oxymethylene units and having a melting point of 50-150 deg.C and a molecular weight of 10000-100000 and optionally additives such as an antioxidant, a nitrogenous compound, a lubricant, a nucleator and a mold releasing agent to obtain a polyacetal resin composition. This composition is melt-kneaded for 20sec to 10min at a temperature higher than the melting temperature by 5-100 deg.C, and molded to obtain a substrate. This substrate is optionally subjected to a surface activation treatment by irradiation with short-wavelength ultraviolet rays or corona discharge treatment and then surface-modified by printing with an ultraviolet-curing ink or a thermosetting ink or by coating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface decoration technique for polyacetal resin. More specifically, it relates to a printing / painting method having excellent adhesiveness and a printed / painted product thereof, which uses a specific decorated base material made of a polyacetal resin.

[0002]

2. Description of the Related Art Polyacetal resins have mechanical properties, thermal properties, electrical properties,
It has excellent characteristics in terms of slidability and moldability,
It is widely used in electrical equipment, automobile parts, precision machine parts, etc. as structural materials and mechanical parts. With the expansion of fields in which polyacetal resins are used, improvement in surface decorativeness may be required. However, due to its good stability to chemicals, polyacetal resin can easily peel off the printing / painting from the surface of the substrate by general printing / painting methods, and obtain good printed / painted products. There was a problem that I could not. Japanese Patent Application Laid-Open No. 63-39954, which is one of the conventional techniques for improving printability, discloses a method of printing polyoxymethylene containing a polymer additive by thermal transfer. Since polyoxymethylene has high crystallinity, it has a low affinity with polymer additives and causes problems such as peeling of the surface layer and bleed-out on the surface of the molded product, and there is a problem that it cannot withstand actual use.

[0003]

[Means for Solving the Problems] The present inventors have completed the present invention as a result of intensive studies to solve these problems. That is, the present invention is a method of subjecting a polyacetal resin-decorated base material obtained by molding a polyacetal resin composition containing 1 to 40% by weight (in the composition) of an aliphatic polyether resin to a surface-decorating treatment. And a surface-decorated product obtained by this method. More specifically, it is generally used for a decorated base material made of a polyacetal resin obtained by molding a polyacetal resin composition containing 1 to 40% by weight (in the composition) of an aliphatic polyether resin. The present invention relates to a method of printing and coating with ink or paint and a printed / painted article obtained by this method. According to the present invention, a printed / painted article having excellent adhesion can be obtained. In the present invention, preferably a surface activation treatment is carried out in advance at the time of printing, and the adhesion is further improved by printing. More preferably, as the surface activation treatment, relatively easy handling, and by performing short-wavelength ultraviolet irradiation or corona discharge treatment that can be carried out with relatively inexpensive equipment introduction, the production of printed matter is relatively easy and Can be effective. In addition, during coating, if necessary, the same pretreatment as described above, primer coating, or both treatments may be performed to further improve the adhesion between the coating material and the polyacetal resin print coating substrate. In addition, the decorated base material made of a polyacetal resin containing an aliphatic polyether-based resin can withstand actual use without peeling off the surface layer due to the affinity between the polyacetal and the aliphatic polyether-based resin.

The specific constitution of the present invention will be described in detail below. The present invention is characterized in that a normal polyacetal resin is blended with an aliphatic polyether resin to form a base material having good surface decoration. The polyacetal resin used in the present invention is a polymer compound having an oxymethylene unit (--CH ₂ O--) as a main constituent unit, a polyoxymethylene homopolymer, or an oxymethylene group as a main repeating unit, and other than this. May be any other structural unit, for example, a copolymer containing a small amount of a comonomer unit such as ethylene oxide, 1,3-dioxolane, 1,4-butanediol, formal, etc., a terpolymer, or a block polymer. It may have not only a linear structure but also a branched or crosslinked structure. Also, there is no particular limitation on the degree of polymerization, and those having moldability (for example, 190 ° C,
Melt flow value (MFR) under load of 2160g is 1.0 to 10
0) is enough. Further, additives necessary for improving the adhesive strength may be added.

The aliphatic polyether resin blended with the above polyacetal resin is not particularly limited as long as it contains 75 to 93 mol% of oxymethylene groups in the repeating alkylene oxide, and the repeating alkylene oxide unit. A copolymer containing 1,3-dioxolane units in an amount of 8 to 33 mol%, and a repeating alkylene oxide unit containing 1,4-butanediol formal units in an amount of 8 to 33 mol%.
Preferred examples include copolymers containing 33 mol% and copolymers containing 4 to 17 mol% of units of diethylene glycol formal in repeating alkylene oxide units. These are, for example, one or more of cyclic ethers or cyclic formal (ethylene oxide, 1,3-dioxolane, 1,4-butanediol formal, diethylene glycol formal, etc.) having at least two adjacent carbon atoms in trioxane. Is copolymerized in the presence of a catalyst such as boron trifluoride dibutyl ether. The smaller the amount of oxymethylene groups in the repeating alkylene oxide groups of the aliphatic polyether resin, the greater the effect of improving printing and paintability, but if it is too small, the physical properties of the polyacetal base material when blended with polyacetal will be reduced. Therefore, the amount of oxymethylene groups is preferably 75 mol% or more. A particularly preferred aliphatic polyether resin is trioxane 80-40.
A copolymer consisting of 20 to 60 mol% of 1,3-dioxolane and 89 to 62 mol% of trioxane and 11 to 38 mol% of diethylene glycol formal. Further, the structural unit may or may not have a side chain. An example of the method for producing the above aliphatic polyether resin is obtained by mixing trioxane and 1,3-dioxolane at a predetermined ratio and reacting them in the presence of an acid catalyst. The aliphatic polyether resins include those having a relatively low molecular weight to those having a high molecular weight, but those having a molecular weight of 10,000 to 100,000, particularly about 50,000 are preferable. The melting point is also not particularly limited, but it is preferably 50 to 150 ° C. in order to avoid deterioration of physical properties inherent to the polyacetal base material when blended with the polyacetal.

It is desirable to add various known stabilizers to the composition used in the present invention to enhance the thermal stability. For this purpose, known antioxidants, nitrogen-containing compounds, alkali or alkaline earth metals are added. It is desirable to use one kind or a combination of two or more kinds of metal compounds and the like. Further, in order to add desired properties to the composition of the present invention in addition to the above, conventionally known additives such as a lubricant, a nucleating agent, a release agent, an antistatic agent and other surfactants, or an organic polymer system. It is possible to add and mix materials and the like. Further, it is possible to add and contain an organic polymer material or the like which is the object of the present invention. It is also possible to mix one or more known fillers such as fibrous, plate-like, and powder-like inorganic, organic, metallic, etc. fillers as long as the performance of the molded product is not significantly deteriorated. Is. Examples of such inorganic fillers include, but are not limited to, glass fibers, potassium titanate fibers, glass beads, talc, mica, white mica, wollastonite, and the like.

The polyacetal resin composition of the present invention can be prepared by various known methods, but it is heated and melted in the coexistence of two components, a polyacetal resin and an aliphatic polyether resin, and kneaded for 20 seconds or more. Need to be processed,
Other components may be used in combination at the same time, or may be added separately. Specifically, a polyacetal resin, an aliphatic polyether resin, and, if necessary, other additives are uniformly mixed in advance with a mixer such as a tumbler or a Henschel mixer, and then mixed into a single-screw or twin-screw extruder. The method of supplying and melt-kneading is generally used, and an open roll, Banbury mixer, kneader or the like may be used. It is preferable to dry each component in advance before kneading. The resin composition kneaded by these methods may be pelletized and then directly molded. The treatment temperature is 5 ° C to 100 ° C higher than the melting temperature of the resin component, and particularly preferably 10 ° C to 60 ° C higher than the melting temperature of the mixture of both.
It is a high temperature. If the temperature is too high, decomposition will occur, which is not preferable. Further, the melt-kneading treatment time is at least 20 seconds or more and 10 minutes or less, preferably 1 to 5 minutes. The blending amount of the aliphatic polyether-based resin with respect to the polyacetal resin is 1 to 40% by weight in the polyacetal resin composition, and when blended in an excessively large amount, the physical properties of the polyacetal resin decrease, and when blended in an excessively small amount, surface decoration There is a problem that the effect of improving the sex is low. It is preferably about 20 to 30% by weight.

As the decorated base material made of polyacetal containing such an aliphatic polyether resin, an injection molding method,
It is obtained by a generally known plastic molding method such as an extrusion molding method and a blow molding method, and the shape thereof is not particularly limited, but for example, an automobile interior part (inner handle, fuel lid opener, Trunk lid opener, seat belt buckle button, etc., electrical / electronic parts (keyboard key top,
Examples thereof include parts such as floppy disk shutters) and other parts for various industries that require some surface decoration treatment in terms of their function or design.

Next, the formed decorative base material made of polyacetal resin is subjected to surface decoration treatment by a known method to obtain a final printed / painted product. In the above surface decoration treatment, it is preferable that the molded decorated substrate is subjected to a surface activation treatment in advance, because the adhesion becomes stronger. As the surface activation treatment, short-wavelength ultraviolet irradiation, corona discharge treatment, plasma treatment, electron beam irradiation, etc. are suitable, particularly short-wavelength ultraviolet irradiation or corona that is easy to handle and can be implemented with relatively inexpensive equipment. Discharge treatment is preferred. As a typical surface decoration method, any method such as screen printing, offset printing, stamp printing, etc. may be used, and spray coating, brush coating, etc. may be used as the coating method. The ink / paint used in the surface decoration treatment of the present invention is not particularly limited, but in consideration of actual use, an ultraviolet curable type and a thermosetting type are preferable.
The ultraviolet curable ink used in the present invention is generally composed of components such as a photopolymerizable prepolymer, a reactive diluent, a photoinitiator, a photoinitiator aid, a coloring agent (pigment), and other additives. It is a common thing. As the photopolymerizable prepolymer, polyester acrylate, polyurethane acrylate and the like are generally well known. The reactive diluent is
Generally, many of them have low molecular weight, low viscosity, low volatility and high solubility. As the reactive diluent, a monofunctional acrylate,
There are bifunctional acrylates, trifunctional or higher functional acrylates, and the like. The photoinitiator absorbs ultraviolet rays to start the polymerization reaction and has absorption in the ultraviolet region of 300 to 450 nm. Main photoinitiators include carbonyl compounds, sulfur compounds and azo compounds. The photoinitiator aid does not activate by irradiation with ultraviolet rays by itself, and when used in combination with the photoinitiator aid, the photoinitiator aids in increasing the reaction efficiency as compared with the case of using the photoinitiator alone. The main photoinitiator aids are amines (aliphatic amines, aromatic amines, etc.), urea compounds (o-tolylthiourea, etc.), sulfur compounds (sodium diethyldithiophosphate, aromatic sulfone soluble salts, etc.), N, N −
Di-substituted-p-aminobenzonitrile compounds, phosphorus compounds (tri-n-butylphosphine, sodium diethyldithiophosphate, etc.), other nitrogen compounds (oxazolidine compounds, tetrahydro-1,3-oxazine compounds, Michler's ketone, etc.), chlorine There are compounds such as carbon tetrachloride and hexachloroethane. The ultraviolet curable ink used in the present invention may further contain a pigment,
Additives such as fillers, inert organic polymers, leveling agents, thixotropic agents, and thermal polymerization inhibitors are added. Further, additives necessary for improving the adhesive strength may be added. Such an ultraviolet curable ink is widely commercially available. The thermosetting ink used in the present invention is a general commercially available one, and is not particularly limited as long as it is a thermosetting ink such as an epoxy type and a melamine type. The thermosetting ink used is diluted with a general thinner or the like as necessary.

Further, the paint used for painting is not particularly limited, and may be a known paint generally used for painting plastics. Thermosetting paints are preferable, and commercially available ones such as two-component urethane type and melamine type may be used. In addition, it is preferable that the surface of the base material to be decorated is subjected to a surface activation treatment in advance, if necessary, at the time of coating because the adhesion becomes stronger. As the surface activation treatment, short-wavelength ultraviolet irradiation, corona discharge treatment, plasma treatment, electron beam irradiation, etc. are suitable, particularly short-wavelength ultraviolet irradiation or corona that is easy to handle and can be implemented with relatively inexpensive equipment. Discharge treatment is preferred. You may treat with a primer if necessary. As a method of painting, any method such as spray painting or brush painting may be used.

[0011]

EFFECTS OF THE INVENTION As described above, a molded article made of a polyacetal resin composition containing an aliphatic polyether resin is excellent in printed film adhesion of a printed matter printed with an ultraviolet curable ink or a thermosetting ink. It is recognized that it is an excellent product that can withstand actual use, and it has excellent paintability as well.
It is recognized that the coating film adhesion of the coated material is excellent enough to withstand actual use by coating with a general coating material, and the method according to the present invention utilizes the characteristics of the superior polyacetal resin. enable. Therefore, the printed matter using the substrate to be printed made of the polyacetal resin composition of the present invention, the coated article, in terms of function or design, molded parts in all fields that require some surface decoration treatment, that is, automobile interior parts ( Suitable for inner handles, fuel lid openers, trunk lid openers, seat belt buckle buttons, etc., electrical / electronic parts (keyboard key tops, floppy disk shutters, various display panels, etc.) and other industrial parts, household items, etc. obtain.

[0012]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.
In the examples, the method used to evaluate the adhesion of the printed film is as follows. [Cellophane tape peeling test] Stick the cellophane tape on the printed part or the painted part on the test piece, rub it well with the finger to make it adhere to the test piece, and pinch one end of the cellophane tape with the finger to put the tape all at once. Peel it off and observe the peeling condition of the printing section. Judgment of evaluation was performed using the evaluation criteria of 10 points (no peeling at all) to 0 points (marked peeling). [Cross-cut peeling test] Interval of cells is 1 mm, number of cells is 10
Performed by the 0-cut grid method, and the evaluation method and judgment criteria are JIS K 540
It carried out according to 0. [Tensile Strength Test] The tensile strength of each printed coated substrate was measured by a tensile tester according to the test method of ASTM D638. Examples 1 to 3 polyacetal resin (DUR manufactured by Polyplastics Co., Ltd.)
ACON M90-44) with polymer A (40 mol% 1,3-dioxolane, 60 mol trioxane) as an aliphatic polyether resin.
1% copolymer) was mixed at the compounding ratio shown in Table 1 and melt-kneaded using an extruder to prepare a pelletized composition. Then, the pellets were molded using an injection molding machine.
A flat plate having a size of cm × 5 cm and a thickness of 3 mm was formed. This molded product is irradiated with short-wavelength ultraviolet light as a surface activation treatment in advance (main wavelength 253.
Irradiate for 30 seconds with an ultraviolet irradiation device that uses a low-mercury lamp with a output of 7W and a power of 200W for 30 seconds, and then perform a predetermined screen printing on the molded product with an ultraviolet curable ink (Dainippon Ink Co., Ltd., Dicure SSP White). After that, the printed film was cured by UV irradiation treatment (with a UV irradiation device using a high-pressure mercury lamp with a main wavelength of 365 nm and an output of 120 W, the speed of the test piece during processing was 1.5 m / nin), and an evaluation sample was obtained. The above evaluation was performed. The results are shown in Table 1. Example 4 Corona discharge treatment (processing speed 1.5 m / min, output 12
0W), and the same printing and curing treatment as in Example 1,
An evaluation sample was obtained and the above evaluation was performed. The results are shown in Table 1. Example 5 Plasma treatment immediately before printing (pressure 0.07 torr, oxygen flow rate 1
cm ³ / min, output 170 W, processing time 3 minutes), Example 1
The same printing and curing treatment as in (1) above was performed to obtain an evaluation sample, and the above evaluation was performed. The results are shown in Table 1. Example 6 The same printing as in Example 1 was performed without surface treatment just before printing,
Curing treatment was performed to obtain an evaluation sample, and the above evaluation was performed.
The results are shown in Table 1. Example 7 Polyacetal resin (DUR manufactured by Polyplastics Co., Ltd.)
ACON M90-44) was mixed with Polymer B (a copolymer of 1,4-butanediol formal 40 mol% and trioxane 60 mol%) as an aliphatic polyether resin at the compounding ratio shown in Table 1, and then melted using an extruder. The composition was kneaded to prepare a pellet-shaped composition. Other than that, the same printing and curing processes as in Example 1 were performed to obtain an evaluation sample, and the above evaluation was performed. The results are shown in Table 1. Example 8 A polyacetal resin (M90-44 manufactured by Polyplastics Co., Ltd.) was mixed with a polymer C (a copolymer consisting of 22 mol% of diethylene glycol formal and 78 mol% of trioxane) as an aliphatic polyether resin as a printing substrate for evaluating printability. Melt kneading was performed using a post-extruder to prepare a pelletized composition. Other than that, the same printing and curing processes as in Example 1 were performed to obtain an evaluation sample, and the above evaluation was performed. The results are shown in Table 1. Comparative Examples 1 to 4 A molded article having each of the base material compositions shown in Table 1 was directly (without surface activation treatment) or subjected to each surface activation treatment shown in Table 1 and then, Example 1 The printed film was cured by the same printing and ultraviolet irradiation treatment as in (1) to obtain an evaluation sample, and the above evaluation was performed. The results are shown in Table 1.

[0013]

[Table 1]

Examples 9 to 11 Polyacetal resin (DUR manufactured by Polyplastics Co., Ltd.)
ACON M90-44) with polymer A (40 mol% 1,3-dioxolane, 60 m trioxane) as an aliphatic polyether resin.
ol% copolymer) at the compounding ratio shown in Table 2 and then melt-kneaded using an extruder to prepare a pelletized composition. Then, the pellets were molded using an injection molding machine.
A flat plate having a size of cm × 5 cm and a thickness of 3 mm was formed. This molded product is irradiated with short-wavelength ultraviolet light as a surface activation treatment in advance (main wavelength 253.
Irradiate for 30 seconds with an ultraviolet irradiation device that uses a low-mercury lamp with a output of 7W and a power of 200W for 30 seconds), and then apply a predetermined spray coating on the molded product with a thermosetting ink (Retan PG60 manufactured by Kansai Paint), and then heat cure. Treatment (80 ℃ × 30min
) To cure the coating film, obtain an evaluation sample,
The above evaluation was performed. Table 2 shows the results. Example 12 Corona discharge treatment (treatment speed 1.5 m / min, output 12
0 W), the same coating and curing treatment as in Example 9 was performed to obtain an evaluation sample, and the above evaluation was performed. Table 2 shows the results. Example 13 Plasma treatment just before coating (pressure 0.07 torr, oxygen flow rate 1
cm ³ / min, output 170 W, processing time 3 minutes)
The same coating and curing treatment as above were performed to obtain an evaluation sample, and the above evaluation was performed. Table 2 shows the results. Example 14 The same coating as in Example 9 was carried out without performing the surface treatment immediately before coating,
Curing treatment was performed to obtain an evaluation sample, and the above evaluation was performed.
Table 2 shows the results. Example 15 Polyacetal resin (DUR manufactured by Polyplastics Co., Ltd.)
ACON M90-44) was mixed with Polymer B (a copolymer of 1,4-butanediol formal 40 mol% and trioxane 60 mol%) as an aliphatic polyether resin at the compounding ratio shown in Table 2 and then melted using an extruder. The composition was kneaded to prepare a pellet-shaped composition. Other than that, the same coating and curing treatment as in Example 9 was performed to obtain an evaluation sample, and the above evaluation was performed. Table 2 shows the results. Example 16 Polyacetal resin (DUR manufactured by Polyplastics Co., Ltd.)
ACON M90-44) was mixed with Polymer C (copolymer consisting of 22 mol% of diethylene glycol formal and 78 mol% of trioxane) as an aliphatic polyether resin at a compounding ratio shown in Table 2, and then melt-kneaded with an extruder to form pellets. A composition was prepared. Other than that, the same coating and curing treatment as in Example 9 was performed to obtain an evaluation sample, and the above evaluation was performed. Table 2 shows the results. Comparative Examples 5 to 8 A molded article having each substrate composition shown in Table 2 was directly (without surface activation treatment) or after each surface activation treatment described in Table 2, the same as Example 9. Painting of the
The evaluation was performed by performing a curing treatment to obtain an evaluation sample. Table 2 shows the results.

Example 17 Polyacetal resin (DUR manufactured by Polyplastics Co., Ltd.)
ACON M90-44) with polymer D (1,3-dioxolane 80mol%, trioxane 20m as an aliphatic polyether resin
ol% copolymer) at the compounding ratio shown in Table 2 and melt-kneaded using an extruder to prepare a pelletized composition. Other than that, the same coating and curing treatment as in Example 9 was performed to obtain an evaluation sample, and the above evaluation was performed. Table 2 shows the results.

[0016]

[Table 2]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location C08L 59/00 LMP

Claims (16)

[Claims] 1. A surface decoration treatment method for surface-modifying a substrate formed by molding a polyacetal resin composition containing 1 to 40% by weight of an aliphatic polyether resin. 2. The aliphatic polyether-based resin has 75 to 93 repeating oxymethylene units in a repeating alkylene oxide group.
The surface decoration treatment method according to claim 1, which contains a mol%. 3. The surface decoration treatment method according to claim 2, wherein the aliphatic polyether-based resin is a copolymer containing 8 to 33 mol% of a unit consisting of 1,3-dioxolane in a repeating alkylene oxide unit. 4. The surface decoration treatment method according to claim 2, wherein the aliphatic polyether resin is a copolymer having a repeating alkylene oxide unit containing 8 to 33 mol% of a unit consisting of 1,4-butanediol formal. . 5. The surface decoration treatment method according to claim 2, wherein the aliphatic polyether resin is a copolymer containing 4 to 17 mol% of a unit composed of diethylene glycol formal in a repeating alkylene oxide unit. 6. The surface decoration treatment method according to claim 1, wherein the aliphatic polyether resin is a copolymer using trioxane as a raw material of repeating alkylene oxide units. 7. The aliphatic polyether resin has a melting point of 50.
The surface decoration treatment method according to any one of claims 1 to 6, wherein the surface decoration treatment method is performed at a temperature of up to 150 ° C. 8. The surface decoration treatment method according to claim 1, wherein a surface activation treatment is performed on the surface of the polyacetal substrate in advance before the surface decoration. 9. The surface decoration treatment method according to claim 8, wherein the surface activation treatment is a short-wavelength ultraviolet treatment or a corona discharge treatment. 10. The surface decoration treatment method according to claim 1, wherein a primer is applied to the surface of the polyacetal substrate in advance before the surface decoration treatment. 11. The surface decoration treatment is printing.
10. The surface decoration treatment method according to any one of 10. 12. The surface decoration treatment method according to claim 11, wherein the printing is performed with an ultraviolet curable ink. 13. The surface decoration treatment method according to claim 11, wherein the printing is performed with a thermosetting ink. 14. The surface decoration treatment is painting.
10. The surface decoration treatment method according to any one of 10. 15. The surface decoration treatment method according to claim 14, wherein the coating is performed with a thermosetting coating material. 16. A surface-decorated product made of a polyacetal resin, which is produced by the method of surface-decoration according to claim 1.