CN100471910C - Modified polyacetals for decorative applications - Google Patents

Abstract

A painted polyacetal article comprises a polyacetal substrate comprising 90 - 99.5wt% polyacetal and 0.5 - 10wt% of semicrystalline or amorphous thermoplastic non-polyacetal resin of molecular weight 1,000 - 50,000; and a paint applied to the polyacetal substrate from a solvent-borne, water-borne or powder 1K paint system onto a surface of the polyacetal substrate pretreated to enhance exposure of said semicrystalline or amorphous thermoplastic non-polyacetal resin of the substrate to the applied paint. The paint is a thermoplastic or partly thermoplastic non-thermosetting paint. A layer of thermosetting paint or varnish can be applied over the thermoplastic paint. The painted polyacetal article has improved paint adhesion and good retained physico-mechanical properties.

Description

The modified polyacetal that is used for decorative applications

Invention field

The present invention relates to the body modification of polyacetal articles, before the coating paint systems, carry out chemical etching and/or machinery or physical treatment subsequently, the kind of paint systems can be solvent base, water base and/or powder type. the present invention relates to have and improve paint adhesion and the good coating polyacetal articles that keeps physical and mechanical properties, with and production method.

Background of invention

Polyacetal (being sometimes referred to as Derlin) is a class polyformaldehyde composition, for example is described in United States Patent (USP) 5,318,813,5,344,882 and 5,286,807. polyacetal resins are by commercialization, especially E.I.du Pont de Nemours and Company, Wilmington, Delaware, USA, trade mark is

Polyformaldehyde composition (polyacetal) is generally understood as and comprises composition, described composition is based on the homopolymer of formaldehyde or formaldehyde cyclic oligomer (for example trioxane), the end group by esterification or the described homopolymer of etherified sealed end wherein, and based on the multipolymer of formaldehyde or formaldehyde cyclic oligomer, oxyalkylene group has at least two adjacent carbonss in its main chain, the end group of described multipolymer can be hydroxy-end capped maybe can be by esterification or etherified sealed end.

By the general any technology used of thermoplastic material, for example compression moulding, injection moulding, extrusion molding, blowing, rotational moulding, melt-spinning, punching press and thermoforming, will be based on relative high molecular (promptly 10,000 to 100,000) composition of polyoxymethylene is used to prepare work in-process and finished product. and the finished product of being made by said composition has extremely desirable physicals, comprises high stiffness, intensity, chemical stability and solvent resistance.

Known, height chemically stable and the crystalline moulded work of being made by polyacetal more are difficult to decorate or overmolding than other moulded plastic material, and especially more are difficult to metallization (by vacuum moulding machine) or plating (electroless plating or plating) or japanning.

Because the adhesivity of paint is low, high crystalline or have the plastics of low surface polarity, particularly polyacetal carries out physics or chemical surface treatment before applying paint usually thereon. the treating method comprises the physical method of mechanical coarse finished surface, the chemical process of solvent treatment, flame treating, UV treatment, Corona discharge Treatment and Cement Composite Treated by Plasma.All these methods all are intended to improve the adhesivity of paint by making the plastic surface sex change.

In general, plastics are quite stables aspect chemical property, its moulded work by manufacturings such as injection mouldings has smooth surface, makes it be difficult to decorate its surface by printing, coating, deposition etc., and it also is difficult to stand surface working and for example utilizes tackiness agent to adhere to.Because the polyacetal resin surfactivity is low especially, and the known suitable solvent that does not have with the polyacetal affinity, be difficult to carry out polyacetal surface in practice and decorate or adhere on it, make the purposes that polyacetal resin seldom drops into needs this processing.

Yet the application variation of plastics, and high value purposes recently often need be satisfied the volume index simultaneously, for example functional and outward appearance or functional and adhesivity. therefore, the surface of good processing characteristics becomes more important for polyacetal.

By handling with acidic solution or oxidizing agent solution, can improve the surface working performance of polyacetal to a certain extent. the acidic solution of tosic acid, camphorsulfonic acid, phosphoric acid, ammonium acid sulfate has been proposed, the oxidizing agent solution of chromic acid-sulfuric acid mixture has been proposed simultaneously. improved electro-plating method is provided in addition, method comprises: before the sour reagent solution surface treatment of above-mentioned usefulness, the submergence moulded products enters the technology of quinoline, pyridine or g-butyrolactone.

The purpose of these processing is to produce uneven surface, oxygenizement by solution simultaneously, yet on part polyacetal molecule, form reactive group., if attempt by this method enhanced surface treatment effect, all polyacetal resin deteriorations that for example will have problems cause strength degradation, form crack or poor surface finish. and on the other hand, do not cause the condition of polyacetal deterioration to be handled if utilize, the surface-treated effect is tended to deficiency, and can not carry out surface of good processing.

When handling polyacetal articles when improving its surface working performance, by in the chemical modification control surface activation and selecting polyacetal composition to keep running into sizable problem in its initial ensemble character. in addition, observe the difficulty that susceptible of proof is handled the polyacetal resin surface by several, for example when complicated profiled part is immersed in the acidic solution poor adhesion of scrap rate height, paint systems and/or, particularly, it is poor to test the floating coat property retention for a long time.

The difficulty of metallization polyacetal articles for example is described in GB-A 2,091 274, and it proposes the preliminary surface treatment by acid etching, for example uses 30-60wt% sulfuric acid, 5-30wt% hydrochloric acid and 65-10wt% water; Or 20-50wt% sulfuric acid, 30-50wt% phosphoric acid and 50-0wt% water. also imagined organic and mixture mineral acid. behind the acid etching, goods are immersed in the neutral solution, use the polyurethane paint linging, metallize by cathode sputtering, and apply top layer with acrylic acid series polyurethane paint or acrylic acid series ester oil lacquer system.

French Patent specification sheets FR-A-2,703,074 has described the preliminary surface treatment of polyacetal articles, so that they are ready for carrying out plating, its method comprises: use sulfuric acid, the mixed acid bath etch of phosphoric acid and hydrochloric acid, described mixing acid comprises 30% (volume) sulfuric acid (96/98% purity), 20% (volume) phosphoric acid (85% purity), 5% (volume) hydrochloric acid (35/37% purity) and 45% (volume) water. this method successfully has been used for the goods that plating is made by Copolyacetal on a small scale to a certain extent, but because described restriction, its technical scale live telecast is unsatisfactory. and in addition, this method is used for directly applying paint for decoration to polyacetal articles and also has problem.

Although meet difficulty up to now, the surface treatment polyacetal articles still extremely needs, especially surperficial apparent weight to, be kept the application of good physical and mechanical properties of polyacetal and secular paint adhesion simultaneously. as mentioned above, applying now the problem that exists many needs to overcome in the melt-processed polyacetal resin product. verified existing method do not meet the demands for applying many polyacetal articles, particularly complicated shape.

Summary of the invention

The invention provides a kind of polyacetal articles of coating, it comprises: the polyacetal base material comprises 90-99.5wt% polyacetal and 0.5-10wt% molecular weight 1,000-50,000, common 5,000-50, the non-polyacetal resin of 000 hypocrystalline or amorphous thermoplastic; Be applied to the lip-deep paint that the polyacetal base material is applied of pre-treatment polyacetal base material by solvent base, water base or powder 1K paint systems, described pretreated purpose is to increase the described hypocrystalline of base material or the non-polyacetal resin of amorphous thermoplastic to applying the exposure of paint. this applies paint and is thermoplasticity or portion of hot plasticity paint.

It is low that surface-treated polyacetal articles of the present invention is characterized as scrap rate, scrap rate is defined as the per-cent of following profiled part herein, promptly when the surface treatment profiled part, particularly when they are immersed acidic solution, the destructive profiled part, or observe its surface and go up such as the profiled part that forms fissured defective.Should be connected with special significance to blocky ＂ complicated form part of ＂ such as slide plate by low scrap rate.

The present invention applies polyacetal articles and is characterized as, with comprise the Surface Modification Of Inorganic Fillers polyacetal resin that dissolves in acidic solution and/or surface part or extensively compare by strong surface treatment activatory polyacetal parts, coating property of having improved (paint adhesion) and the good physical and mechanical properties that keeps, be stiffness and toughness. according to the present invention, applying polyacetal articles in addition is characterized as, improved harsh aging (80 ℃, 100% RH, 100-150 hour) the long-term adhesivity in back, the latter measures according to ISO 2409. and apply polyacetal articles and keep, for example, at following condition: 0.5W/m ², under black plate temperature=65 ℃, behind 150 hours accelerated weathering agings, the physical impact performance of measurement.

The advantage that the present invention applies polyacetal articles and method has a lot:

I) surface wettability is improved, the surface energy phenomenal growth;

Ii) behind the surface active, scrap rate reduces, and the process yield height is particularly by being immersed in the acidic solution after the activation;

Iii) improved coating property and aging (80 ℃, 100% RH, 100-150 hour) back paint adhesion: and

Iv) keep applying the physicals of polyacetal articles, even after weathering age.

The accompanying drawing summary

In the accompanying drawing:

Fig. 1 a and 1b are after having showed two kinds of unmodified polyacetal base materials of coating, the adhering photo of observed typical surface defective and difference.

Fig. 2 a and 2b are respectively the photos that bad paint systems and the present invention improve the paint systems of coating property and long-term aging.

Fig. 3 illustrates modified polyacetal resin to be improved in the mechanical property of precoating process different steps with respect to unmodified polyacetal resin.

Describe in detail

The invention provides the coating polyacetal articles that has good maintenance physical and mechanical properties and improve paint adhesion and high yield.

The present invention relates to some polyacetal composition, after its melt production (as by injection moulding) carry out appropriate postprocessing (burning, sandblast, corona discharge, plasma body, ultraviolet ray etc.). preferred aftertreatment is for to carry out etch with mixed acid bath, wherein mixed acid bath comprises and is selected from sulfuric acid, phosphoric acid, hydrochloric acid and at least three kinds of acid of organic acid, being more preferably and comprising four kinds of acid: sulfuric acid, phosphoric acid, hydrochloric acid and acetate. polyacetal composition comprises sense and improves chaste tree (following description), it keeps the good character of polyacetal, and it is used to strengthen paint adhesion.

Demonstrate good maintenance mechanical property, in the different polyacetal resin prescriptions of low scrap rate (high yield) and well applied performance, preferred resin comprises the blend of first and second polyamide copolymers (describing hereinafter) with different molecular weight. for example, first polymeric amide has the molecular weight than second polymeric amide big at least 5000, first polyamide molecular weight is 20,000 to 50,000, amount is 0.5-5wt%, second polyamide molecular weight is 1,000 to 25,000, amount is equal to or less than first polymeric amide, and be that 0.1-2.5wt%. is preferred, the first polymeric amide amount is 1-2wt%, the second polymeric amide amount be 0.25-1.5wt%. more preferably, resin comprises molecular weight about 40,000, a kind of polymeric amide of amount about 1.5%, and molecular weight about 18,000, second polymeric amide of amount about 0.5%.

As described below being applied by solvent base, water base or powder-coating system painted the polyacetal base material.

According to the coating molding polyacetal resin product of the present invention by resin combination, surface treatment and thermoplasticity that applies or the acquisition of portion of hot plasticity paint, required high-performance (good adhesivity, stiffness, toughness etc.) is provided, and more details is described hereinafter.

Polyacetal

The term ＂ polyacetal ＂ of Shi Yonging comprises the homopolymer of formaldehyde homopolymer or formaldehyde cyclic oligomer herein, its end group is by esterification or etherified sealed end, and the monomeric co-polymer of formaldehyde or formaldehyde cyclic oligomer and other generation oxyalkylene group, have at least two adjacent carbonss in the main chain, end group can be hydroxy-end cappedly maybe can be esterification or etherified sealed end in the multipolymer.

The polyacetal that uses in the present composition can be branching or linearity, has 10,000 to 100,000 number-average molecular weight usually, and preferred 20,000 to 75,000. can have nominal pore size 60 Hes with 160 ℃ of uses in meta-cresol Bimodal column kit device, although measure molecular weight easily with gel permeation chromatography. depend on required physics and working properties, can use polyacetal with higher or lower molecular-weight average, preferred above-mentioned polyacetal molecular-weight average, want melt blending to enter the optimum balance of the multiple composition well blend of composition to provide, the moulded work of being made by said composition has the most desirable combination of physical properties.

As noted before, polyacetal can be homopolymer, multipolymer or its mixture. multipolymer can comprise one or more and plant comonomer, for example prepares in the polyacetal composition normally used.More generally the comonomer of Shi Yonging comprises that the ring-type of the oxyalkylene of 2-12 carbon atom and itself and formaldehyde adds and thing. the amount of comonomer is not more than 20wt%, preferred 15wt% at the most, most preferably from about 2wt%. most preferably comonomer be oxyethane. usually polyacetal homopolymer is preferable over multipolymer, because its stiffness and intensity are bigger. preferred polyacetal homopolymer comprises that terminal hydroxyl forms ester or ether group person by the chemical reaction end-blocking, respectively preferred acetic ester or methoxy group.

Common at about 170 ℃-260 ℃ melt temperature melt-processed polyacetal, preferred 185 ℃-240 ℃, most preferably 200 ℃-230 ℃.

Function improver

Have been found that, polyacetal can be formulated in to have in the composition that improves coating property and good maintenance physical and mechanical properties. compare with unmodified and/or untreated molding polyacetal parts, because property retention, we think that the deterioration of physical and mechanical properties is negligible, for example when using the ballistic pendulum test of 0-40J (or unmemorable 10-15% maximum deviation). more particularly, when using some fusile polymkeric substance (being called ＂ function improver ＂ or ＂ stablizer ＂ or ＂ paint adhesion agent ＂ herein) melt-processed polyacetal in processing temperature, the composition that obtains is characterized as: improved oxidation-resistance or anti-nonacid solution property, the physical and mechanical properties that paint adhesion is better and good.These function improvers comprise hydroxyl, carbonyl and/or amino group, and they have quite low molecular weight. and these function improvers are different from United States Patent (USP) 5,011, the 890 not fusible improving agents of describing.

Comprise hydroxyl, carbonyl, methacrylic ester, the function improver of acid amides and/or amine groups and/or its combination is a fusile in the temperature of processing polyacetal. term ＂ fusile ＂ is meant function improver or different function improver combinations, it has the main fusing point that is lower than melt-processed polyacetal temperature, therefore be liquid, although preferably have low viscosity and significant melt flow take place in processing temperature. the surface enrichment of so-called ＂ low melting point-low viscosity ＂ function improver may quantitatively be described hardly, but presuming, the latter will move towards the surface during the processing, therefore and provide on the so-called skin microstructure that a kind of functional group or multiple functional group exist in processing polyacetal parts or only under it (as measuring proof) by ESCA. in addition, verified, by adding these ＂ low melting point-low viscosity ＂ function improvers, during having or not having the oxidizing solution existence to carry out acid etching, can prevent that the crack from forming.Seem, when adding above-mentioned functions improving agent (one or more) when filling a prescription, inherence or residual stress partial relaxation, the polyacetal parts that processing is provided are with the enhanced mechanical property.

Polyamide (PA) is defined as from cyclic monomer (for example ε-Ji Neixianan) and/or diamines/diacid for example hexanediamine and hexanodioic acid polymeric, include, but are not limited to nylon 6,10,11,12,46,66,69,610,612,1212 and 6T. polymeric amide and comprise multiple multipolymer, terpolymer, tetrapolymer and interpretation (interpolymer), one or more plant dicarboxylic acid and one or more kind diamines production by condensation; The condensation polymer of mono amino carboxylic acid; Polymkeric substance with lactan.

Function improver (paint adhesion agent) with OH base is defined as polymkeric substance with vinyl alcohol and/or phenylol and/or other hydroxyl interpretation (interpretation is meant 2,3,4 or more monomeric units) altogether.

Function improver/paint adhesion agent (adherant) can be acrylate or methacrylic ester (MA), it can hydroxyl, acid amides, imide, carboxylic acid and/or its salt and reactivity is littler or the still less monomeric combination of sense vinylbenzene for example, methyl methacrylate, methacrylic ester, ethyl propenoate, butyl acrylate, glyceral methacrylate, hydroxyethyl methylacrylate. the polymer stabilizer that is used for composition can be to comprise the formaldehyde reaction nitrogen groups, formaldehyde reaction hydroxyl groups or comprise formaldehyde reaction nitrogen simultaneously and the homopolymer or the multipolymer of formaldehyde reaction hydroxyl. ＂ formaldehyde reaction ＂ is meant that hydroxyl comprises the hydrogen atom that oxygen and key are connected to oxygen, nitrogen groups comprises one or two hydrogen atom that nitrogen and key are connected to nitrogen. formaldehyde will with polymer stabilizer-OH or-reaction of NH key. these reactive moieties are called the formaldehyde reaction position herein. preferred, polymer stabilizer comprises formaldehyde reaction nitrogen or the hydroxyl groups with maximum quantity formaldehyde reaction position. for example, the polymer stabilizer that preferably comprises the formaldehyde reaction nitrogen groups, have two hydrogen atoms to be connected directly to nitrogen-atoms in the formaldehyde reaction nitrogen groups, this polymer stabilizer only is better than comprising wherein the formaldehyde reaction nitrogen groups person that a hydrogen atom is connected directly to nitrogen-atoms. the thermoplastic polymer composition

At least a hypocrystalline or amorphous non-acetal thermoplastic polymer can be selected from those in extrusion molding and injection moulding processing, use separately usually or with other thermoplastic polymer that is used in combination. these polymkeric substance, with known resin as minor component in the polymer composition (promptly, processing aid, impact modifier, stablizer) difference, be as extrusion molding and injection moulding grade resin, known to those skilled in the art.

Usually base material of the present invention comprises about 0.5 to 10wt% at least a non-acetal thermoplastic polymer, yet, preferred 1.5 to 5wt% at least a non-acetal thermoplastic polymer. polyoxymethylene of the present invention/thermoplastic polymer blend base material, being included on the substrate surface or neighbouringly having non-acetal polymer resident usually to promote adhering zone. thermoplastic polymer is present in this specific region, reason is, in the flowing mixture of non-molten mixed liquid, the liquid that viscosity is minimum will tend to move to the highest zone of shearing. for example, under the situation of injection moulding, the wall of die cavity is a high-shear region, therefore, the low viscosity polymer melt of higher concentration on the parts surface or near assemble a little.

In the present invention can also be separately or utilize semicrystalline polyamides, polyester and polyolefine in combination with one another, make, separately can be with polyoxymethylene blended to promote adhesivity.

For example; have low-melting relatively polymeric amide and keep some degree of crystallinity; but its low viscosity; high polarity and hydrogen bond make them can be used for purposes of the present invention. verified; polyolefine; preferred polar copolymer and terpolymer be ethylene-vinyl acetate copolymer (EVA) and ethylene butyl acrylate carbon monoxide terpolymer (EBACO) for example; being used between polyoxymethylene base material and the kinds of surface handled thing and forming surface adhesion. semicrystalline polyester can also comprise fusing point usually and be lower than in its vicinity those of polyacetal or fusing point; yet pla-pcl for example. non-acetal thermoplastic polymer can be used as the blend of a kind of thermoplastic polymer or more than one thermoplastic polymers and introduces composition. and the blend of thermoplastic polymer can be used for for example consistency of toughness or main resin and polyoxymethylene of adjusting function.; preferred substrates comprises a kind of other or alternate polymkeric substance, for example amorphous thermoplastic polymers or semi-crystalline polymer.

No matter be to introduce as a kind of thermoplastic polymer or as more than one blend, the wt% of whole non-acetal thermoplastic polymers (one or more) the above-mentioned wt% scope of should exceed not in the composition.

But term ＂ thermoplasticity ＂ be meant polymkeric substance when being heated deliquescing to flow state, in this state under pressure, it can be pressed or be shifted and be entered the cold mould from heating chamber, and after the cooling, its sclerosis also is mold shape in mould. thermoplastic polymer is defined among the Handbook of Plastics and Elastomers (plastics and elastomerics handbook) (being published by McGraw-Hill) in this way.

The amorphous ＂ of term ＂ is meant the polymkeric substance that does not have clear crystalline melting point, does not also have measurable melting heat (although along with cooling off very lentamente from melt, or along with sufficient annealing, can show some crystallinity).On differential scanning calorimeter (DSC), can measure melting heat easily. suitable calorimeter is 990 thermal analyzers of DuPont Company, part number 990000 and pond matrix 11, part number 990315 and DSC pond, part number 900600. uses this instrument, rate of heating that can 20 ℃ of per minutes is measured melting heat. and sample alternately is heated above the temperature of expection fusing point, and by being cooled apace with cooled with liquid nitrogen sample sheath.Measure melting heat any heating period after the first time, and should be for being no more than the definite value of experimental error scope. amorphous polymer is defined as the melting heat measured with this method herein less than 1cal/g's.For example, have semicrystalline nylons 66 polymeric amide of about 17,000 molecular weight, the about 16cal/g. of melting heat

The thermoplastic polymer that is used for this composition must be melt processible under the temperature of melt-processed polyoxymethylene. common melt-processed polyoxymethylene under about 170 ℃-260 ℃ melt temperature, preferred 185 ℃-240 ℃, most preferably 200 ℃-230 ℃.

The melt processible ＂ of term ＂ is meant that thermoplastic polymer must deliquescing or have sufficient flowability, make its can be under polyoxymethylene particular melt processing temperature melt compounded.

Require the minimum molecular weight (1000) of thermoplastic polymer to guarantee consistency, thermostability and maintenance are by means of the mechanical property of chain entanglement, as long as polymkeric substance has at least ten the polymerization degree, and further require polymkeric substance under melt-processed polyoxymethylene temperature be melt processible (promptly, it is in the pressure current downflow). the maximum molecular weight of thermoplastic polymer should be too not high, so that thermoplastic polymer itself can not be with the injection moulding of standard prior art. be used for the polymkeric substance maximum molecular weight (50 of injection moulding processing, 000) however will change with each particular thermal thermoplastic polymer., those skilled in the art judge easily the maximum molecular weight that is used for injection moulding processing.

Useful herein amorphous or hypocrystalline polyamide thermoplastic is as known in the art. they are described in United States Patent (USP) 4,410,661. particularly, these amorphous or hypocrystalline polyamide thermoplastics derive from the aromatic dicarboxylic acid of at least a 8-18 of a comprising carbon atom, with at least a diamines, the latter is selected from: (i) 2-12 the positive structure aliphatics of carbon straight diamine, (ii) 4-18 carbon branched aliphatic diamines, (iii) 8-20 carbocyclic ring aliphatic diamine, comprise at least one cyclic aliphatic part, preferred cyclohexyl; The highest wherein optional 50wt% polymeric amide can by the unit or the aliphatic dicarboxylic acid that must a self-contained 4-12 carbon atom of the lactan of a self-contained 4-12 carbon atom or omega-amino acid and the unit of polysalt that comprises the aliphatic diamine of 2-12 carbon atom are formed.

Term ＂ aromatic dicarboxylic acid ＂ is meant that carboxyl is connected directly on the aromatic nucleus, for example phenylene naphthalene etc.

Term ＂ aliphatic diamine ＂ is meant that amido is connected on the chain that does not contain aromatic base for example alkylidene group.

Term ＂ cycloaliphatic diamine ＂ is meant that amido is connected on the cyclic aliphatic ring, and wherein the cyclic aliphatic ring is made up of 3-15 carbon atom.The ring grease ring of preferred 6 or 12 carbon.

The preferred embodiment of polyamide thermoplastic comprises that fusing point less than about 180 ℃, comprises the multipolymer and the terpolymer of nylon 6,610,612 etc.

Preferably, the non-polyacetal resin of hypocrystalline or amorphous thermoplastic comprises the blend of first and second polymeric amide of different molecular weight. and in the preferred embodiment, first polymeric amide has the molecular weight than second polymeric amide big at least 5000, first polymeric amide has 20,000 to 50,000 molecular weight, amount are 0.5-5wt%, second polymeric amide has 1,000 or 2,000 to 25,000 molecular weight, amount is equal to or less than first polymeric amide, and is 0.1-2.5wt%.

Amorphous or hypocrystalline polyamide thermoplastic descends 105 dyne/cm at 200 ℃ ²Shearing stress is measured down and is demonstrated less than 50, the melt viscosity of 000 pool, preferably less than 20,000 pool. amorphous or semicrystalline polyamides is commercially available, or proportion of composing that can be above-mentioned prepares with known polymkeric substance condensation method. in order to form high-molecular weight polymer, the diacid total mole number of employing should be approximately equal to the diamines total mole number of employing.

In addition, free dicarboxylic acid and its derivative be acyl chlorides for example, can be used to prepare polyamide thermoplastic.

Can prepare amorphous or the hypocrystalline polyamide thermoplastic according to known polymerization technique polymerization, known polymerization technique for example is a melt polymerization, solution polymerization and interfacial polymerization technology, but preferably carry out polymerization according to melt polymerization process. this method is produced has the high-molecular weight polymeric amide. in the polymerization, with a certain amount of hybrid diamine and acid or cyclic amide, make two amine components and dicarboxylic acid components in proportions basically molar weight equate. in the melt polymerization, but under the higher temperature that is lower than its degradation temperature than the polymeric amide fusing point that obtains each component of heating. Heating temperature is about 170 ℃ to 300 ℃. pressure can be vacuum to 300 pound/square inch (approximately 2MPa).The adding method of initial monomers is not crucial. for example, can produce and the salt of combination of hybrid diamine and acid.The mixture that can also disperse diamines in water, the acid mixture that adds specified amount at high temperature be to dispersion, forming the solution of nylon salt mixture, and solution carried out polymerization.

If demand, can with unit price amine or, preferred organic acid is added to mixture or its aqueous solution of initial salt as viscosity modifier.

For the acrylic acid series of the available herein amorphous thermoplastic polymers of extrusion molding and injection moulding grade is known in the art. the amorphous thermoplastic acrylic polymers comprises the polymkeric substance of broad array, wherein main monomer component belongs to two ester class-acrylate and methacrylic ester. and the amorphous thermoplastic acrylic polymers is described in the 103-108 page or leaf of above-mentioned reference EngineeringPlastics (engineering plastics). and the molecular weight of the amorphous thermoplastic polymers of acrylic acid series should be greater than 200,000, because it will be by with the injection moulding of standard prior art. the amorphous thermoplastic acrylic acid polymer is commercially available, maybe can easily prepare with the known technology of those skilled in the art. knownly in this area in addition replace a part of methyl methacrylate can improve the melt viscosity of polymethylmethacrylate with styrene monomer, commercial embodiments can comprise 20 to 60wt% S.

Useful herein amorphous thermoplastic imidization acrylic resin is to know in this area. preparation amorphous thermoplastic imidization acrylic resin is by reaction ammoniacal liquor or primary amine, with acrylic acid polymer, polymethylmethacrylate for example is to form imidization acrylic resin (also being called poly-glutarimide).

The imide acrylic resin will comprise at least about 10% imide, and preferably at least about 40% imide, and can be according to for example U.S. Patent No. 4,246,374 and English Patent 2,101, the description preparation among the 139B.Representational imide polymer comprises for example imidization multipolymer of divinyl, vinylbenzene, ethene, methacrylic acid etc. of imidization poly-(methyl methacrylate) or poly-(methyl acrylate), methyl methacrylate or methyl acrylate and comonomer.

Amorphous thermoplastic imidization acrylic resin also is described in U.S. Patent No. 4,874, and 817. amorphous thermoplastic imidization acrylic acid or the like are commercially available, maybe can easily prepare with the known technology of those skilled in the art.

Other composition of polyacetal

Polyacetal resin does not contain mineral filler usually, but alternatively can comprise the metal-salt that belongs to cycle Table II family, forms the uneven surface that is suitable for surface working by such promotion, but reduces the physical and mechanical properties of described composition.

Except polyacetal and polymer stabilizer, the present composition can comprise other composition, improving agent and the additive that is generally used for polyacetal mold resin, comprises that co-stabilizer (for example is disclosed in U.S. Patent No. 3,960,984; 4,098,843; 4,766,168 and 5,011,890), antioxidant, pigment, tinting material, ultra-violet stabilizer, toughner, nucleator and filler.

Surface treatment

Handle the polyacetal surface that will apply with process for modifying surface, process for modifying surface is selected from cleaning surfaces, etch, burning, ionization, sand milling and ultraviolet exposure, or the useful combination of these processing.The purposes of this processing is the generation uneven surface, and can form on polyacetal part molecule or the exposure reactive group by the oxygenizement of selecting to handle.

The processing of preferably treatment, particularly complicated form part is etch in mixed acid bath, and wherein mixed acid bath comprises and is selected from sulfuric acid, phosphoric acid, hydrochloric acid and at least three kinds of acid of organic acid, particularly comprises the mixed acid bath of sulfuric acid, phosphoric acid, hydrochloric acid and acetate.

For for example two-dimentional moulded work of more uncomplicated shape, burning also is to know and suitable surface treatment. compares with the immersion acidic solution, shortcoming is a profiled part, in case burning, must behind surface active, apply at once, to promote good adhesion best and to avoid priming reaction group recombine.

Sandblast also is suitable for more uncomplicated shape; Yet it needs other cleaning step behind surface roughening, and cause surface aesthetic more unacceptable usually. according to this technology, mechanical set by decoration or functional layer, control most of adhesive power. decoration or functional layer are meant coat of painting, metal level or other coating, and its function provides other functional for example flexible touch, wearing layer or low-friction coating.

Ionization outmost surface layer is meant owing to the result of chemical reaction after high temperature, discharge or radiation forms ion. ultraviolet radiation also can be used for activating surface, and produce some reactive groups, but to promote the wetting property and the adhesivity of paint systems. ultraviolet radiation is meant the radiation of wavelength 250-400nm.

Cleaning surfaces is meant and uses for example Virahol (IPA) wipe surfaces of alcohol.By doing like this, remove the greasy or releasing agent of trace at last from the surface.Cleaning surfaces can be handled with other and combine.

If apply this type of surface treatment to the polyacetal articles that does not comprise necessary function improver, for example whole deterioration of polyacetal resin that will have problems causes strength degradation and forms the crack.

On the other hand, if utilize polyacetal to handle with proper function improving agent, can obtain surface modification, prevent or reduce the deterioration of the polyacetal articles of the physical-mechanical property that keeps good simultaneously, and cause the adhesivity of painting to be improved, even also be like this after long-term aging.

Paint systems

With paint application to the polyacetal base material of handling, employing is by the solvent base, water base, on 100% solid or the pretreated polyacetal base material of the powder-coating 1K paint systems paint surface. drying heats or carries out with light source. and this applies paint and is thermoplasticity or portion of hot plasticity paint. and thermoplasticity (being different from thermoset) polymkeric substance does not have three-dimensional branching. and they are fusile in its specific melt, main by its mechanical property of its molecular weight control. on the contrary, thermosetting polymer does not have fusing point, therefore at high temperature do not melt but decomposes. control its physicals with the three-dimensional network of formation during crosslinked and the cross-linking density of thermosetting polymer.

1K and 2K paint systems are that .1K paint systems that those skilled in the art know only is interpreted as the paint systems that a kind of mixture ＂ by the ＂ composition forms, it applies does not separately operate linking agent with thermal activation or promotor is mixed fast, make that it is can not solidified or basically can not solidified at low temperature. on the other hand, in the 2K paint systems, add blendable second composition and be usually less than 100 ℃ fast setting at low temperatures to provide, wherein second composition be functional response's property composition for example linking agent .2K paint systems be characterized as intrinsic good chemical-resistant reagent/solvent resistance, yet make its desirable use., they are when being applied in the polyacetal base material as undercoat, can not use well, particularly under harsh aging condition.

If 1K paint is based on the thermoset base-material, yet partly or entirely crosslinkedly will cause coating chemical-resistant reagent and solvent., be different from the 2K paint systems, crosslinked higher temperature 140-180 ℃ of acquisition in this case. can also be crosslinked with following paint composite acquisition, wherein base-material reacts under ultraviolet ray, infrared rays and near infrared influence.Yet, when paint has low curing speed, should only be used for the present invention's practice based on the 1K of thermoset base-material paint.

If 1K paint is based on the thermoplasticity base-material, drying only is a physics, yet and a little less than may causing solvent resistance and chemical reagent resistance., the thermoplasticity base-material can also be with particles dispersed form self-crosslinking, the particle that wherein forms dispersion is made up of cross-linked polymer, described at open source literature nonaqueous dispersion (NAD) and microgel, be called the thermoplastic ＂ of ＂ part herein. finish from this particle dispersion and be processed to form film mainly by connecing skill or absorbing the non-gelatin polymer that microgel is examined. the paint systems, compare with the high molecular base-material that is generally used for based on the paint of thermoplasticity base-material, this dispersion provides better solvent resistance.

Crosslinked particle also exists with water dispersion or emulsion form. use principle same as described above here; wherein; crosslinked inside is arranged in particle; with; the aqueous phase particle is stablized in circumgranular external region; and can also be as becoming membrane portions. crosslinked also can passing across the border in granule interior after forming film finished by functional group's reaction. as the non-limiting example of portion of hot plasticity base-material; the self-crosslinking dispersion comprises epoxide; acid; the alkoxy methyl acid amides; methylol amide; hydroxyl; the amine acetoacetoxy groups; isocyano; ketoimine; aldimine; aziridine; oxazoline functional group is wherein known based on the self-crossing emulsion of methylol (methyl) acrylamide.

Primary coat should be thermoplasticity or part thermoplastic (noncrosslinking or partial cross-linked but not heat cured entirely), according to above-mentioned nonaqueous dispersion (NAD) and microgel definition.If base-material is a thermoplastic polymer, should be characterized as lower glass transition temperatures, preferably be lower than 25 ℃, most preferably be lower than 0 ℃, and/or it should use the softening agent modification. softening agent is meant chemical reagent, the stiffness of its reduction amorphous (glassy) thermoplastic resin. its main effect is the molecular mobility that increases polymer chain, so reduce the second-order transition temperature of amorphous resin. under the situation of portion of hot plasticity microgel dispersion, preferred high molecular microgel promptly is higher than 100,000.

The base-material example that is used to paint is Synolac, polyester, acrylic acid or the like, Vinylite, cellulose acetate butyrate, soluble cotton, Resins, epoxy, polymeric amide, polyamine and urethane.

If being used for the paint linking agent example of the thermoplastic paint of part is melamino-for maldehyde, urea formaldehyde, benzoguanamine carboxaldehyde radicals or polyisocyanates. paint systems is the solvent base, typical solvent comprises alcohol, ketone, ether, acetic ester, aromatic hydrocarbon, acid amides, but is not limited to these.

As the example of the best 1K paint systems of testing, for the coating property of improvement is provided, we have:

I) can obtain from EI du Pont de Nemours and Company

Undercoat. this 1K undercoat comprises thermoplasticity base-material system, and wherein base-material is based on cellulose acetate butyrate, not butyraceous polyester, butyl carbamate softening agent and wax dispenser.Wax dispenser is a vinyl acetate/ethylene copolymer.

Tinter is based on pigment and the specific acrylic acid series dispersion resin that comprises enhanced tertiary amine in the undercoat. can with

What system was compared still replaces the undercoat of oil-free polyester also to demonstrate good coating property (paint adhesion) with vinylformic acid.

Ii)

Undercoat is the thermoplastic 1K paint systems of part, can obtain from E.I.duPont de Nemours and Company. this undercoat comprises sour functional acrylic, with dispersed color with as main base-material, acrylic emulsion and chain extension polyester-polyurethane emulsion based on methylol methacrylamide. as passivator, urethane/acrylic acid series mixture dispersion with there is not the similar undercoat of the polyester-polyurethane emulsion of chain extension, also proof has been improved coating property based on low polyphosphate.

In the present invention, apply thermoplasticity or part thermoplastic bottom coating to the modified polyacetal goods, with the adhesivity that offers the best. on thermoplasticity that applies or portion of hot plasticity paint, advantageously cover thermosetting varnish or clear coat then. the maintenance adhesivity of Xing Chenging provides maximum solvent resistance or chemical-resistant notion based on ＂ sandwich notion ＂ or bilayer simultaneously here, wherein the first layer 1K undercoat is that thermoplasticity or part are thermoplastic, and second layer 2K top coat is heat cured.Undercoat is given required color, and obtain the snappiness and the ＂ toughness ＂ of layer by its inherent macromolecular property. need this snappiness, interfacial stress with the crosslinked generation of balance thermoset 2K Clear coating is assembled. under the situation of thermoset 2K undercoat, after aging under saturated humidity, high temperature (80-90 ℃) and long-time (150 hours), observe relatively poor adhesivity usually.

Can pass through dipping, spraying, brushing or powder application of heat plasticity or portion of hot plasticity 1K paint, and the 2K top coat.

As mentioned above, the paint that applies can be to decorate or functional layer. paint can comprise functional additive, and flexible touch, wearing layer or low-friction coating for example are provided, or enhancement layer.

The etch of preparation mixing acid is bathed

The mixing acid etch for preparing the illustrational following composition of the contrast test that is used for following report is bathed: sulfuric acid 34.5wt%; Phosphoric acid 29.0wt%; Hydrochloric acid 4.5wt%; In acetate 8.5wt% and this example of water 23.5wt%., the weight ratio of sulfuric acid and phosphoric acid is 1.18, and the weight ratio of hydrochloric acid and acetate is 0.52.

The etch of application polyacetal articles

By dipping in sanitising agent is bathed, with tensio-active agent (as can be from Shipley SAS ofParis, the PM 900 that France obtains) with weakly alkaline pH, the molding modified polyacetal goods that will apply in the highest 50 ℃ temperature cleaning 2 to 3 minutes, before etch, use water rinse then. perhaps, annealing, cooling, cleaning and rinsing goods.

In above-mentioned mixed acid bath, carried out etch 10 to 30 minutes with 25 to 35 ℃ easily. condition more time of needing of deepfreeze long more. can stirred solution, with even etch modified polyacetal surface.During the etch, for safety and artificial atmosphere and vapour discharge.

Rinsing in water after the etch, neutralization, also hot rinsing of cold rinsing. the dry then etch parts that will apply, be loaded on the support that applies in the line, apply with organic paints, apply with top coat in case of necessity, curing unloads then and checks.

Contrast test

Use commercial unmodifiedly or modified acetal resin is articles injection-moulded, promptly slide plate connects, and is as described below. and in the mixing acid etch was bathed, all parts all carried out above-mentioned surface treatment .1K and/or 2K paint systems such as detailed description and apply.Modified resins comprises two kinds of polymeric amide, and a kind of molecular weight is 40,000, and 1.5%, the second kind of molecular weight of amount is about 18,000, and amount 0.5%. measures paint adhesion according to ISO2409 standard (grid test).

Fig. 1 a and 1b have showed the application mo(u)lded item, i.e. slide plate web member, surperficial picture, its by use two kinds different commercially available unmodified

100 and 100T acetal grade injection moulding preparation. the undercoat paint systems of use is water base 1K paint systems and top coat are 2K acrylic acid series Clear coatings. among Fig. 1 a, observe from the surface aesthetic viewpoint, unacceptable point. these points may be the surface energy imbalance generations by local macromolecular structure control. the picture of Fig. 1 b is immaculate, but it is relatively poor to be characterized as when measuring according to ISO 2409 adhesivity. basically, these pictures have been summarized major defects such as the bad or poor adhesion of the surface aesthetic that runs into when the unmodified Derlin of coating.

Fig. 2 a and 2b have showed the coating mo(u)lded item, i.e. slide plate web member, picture, use modification

100 acetal grade injection mouldings preparation. among Fig. 2 a, undercoat and top coat system all are the 2K thermosetting material. shown in Fig. 2 a left part, at once good adhesion after the coating, observe the adhesivity loss after 120 hours but in 80 ℃ of moisture-saturated atmosphere (100% RH), wear out, shown in Fig. 2 a right side.

Fig. 2 b has showed the sample of the preferred embodiment of the invention, i.e. the new ideas of application of heat plasticity 1K undercoat and 2K thermoset top coat.Compare with Fig. 2 a, this picture clearly proves before wearing out and afterwards, the present invention obtains adhesivity and improves, shown in Fig. 2 b left side and right side difference.

Fig. 3 graphical comparison to apply commercial unmodified

107 NC and modification

To impact the impact property that transition is measured, express with joule. use the 0-40J ballistic pendulum to test, and record value is the i in following time measurement) after moulded parts soon, ii) 150 ℃ annealing 30 minutes after and iii) annealing and etch after. according to this result, can find out unmodified acetal (commerce 107 NC) damaged by etch; Be to lose its impact property hastily after the moulded work etch. on the other hand,, provide favorable mechanical performance and high yield even modification moulded work of the present invention also keeps the high impact property feature of Derlin after etch.Productive rate is defined as the mo(u)lded item per-cent that does not reduce feature behind the surface active greater than the 25-30% shock strength here.

This result clearly illustrates that and only carries out surface-treated and obtain beneficial effect of the present invention with the modified polyacetal of selecting 1K thermoplasticity paint systems directly to be applied to treat surface. promptly use the coating of 1K thermoplasticity paint systems, unmodified polyacetal is not performance (Fig. 1 a and 1b) preferably also. similarly, the directly performance preferably of modified polyacetal that is coated with the 2K thermosetting varniss (even Fig. 2 is a). Fig. 2 b proof applies acetal in harsh aging back the present invention and still has superperformance.Fig. 3 confirms that modified polyacetal is that physical property institute is essential after keeping surface treatment.

Claims (15)

1. one kind applies polyacetal articles, comprises:

-polyacetal base material comprises 90-99.5wt% polyacetal and 0.5-10wt% molecular weight 1,000-50, and the non-polyacetal resin of 000 hypocrystalline or amorphous thermoplastic, the non-polyacetal resin of wherein said hypocrystalline or amorphous thermoplastic comprises:

The blend of first and second polymeric amide of different molecular weight, wherein said first polymeric amide has the molecular weight than described second polymeric amide big at least 5000, described first polyamide molecular weight is 20,000 to 50,000, the described first polymeric amide amount is 0.5-5wt%, described second polyamide molecular weight is 1,000 to 25,000, the described second polymeric amide amount is 0.1-2.5wt%, and wherein said each polymeric amide has (i) 105 dyne/cm under 200 ℃ ²Shearing stress is measured the melt viscosity that demonstrates less than 50,000 pools down, and the amount of wherein said second polymeric amide is equal to or less than described first polymeric amide; With

-thermoplasticity or the thermoplastic paint of part that described polyacetal base material is applied, described paint is applied on the pretreated described polyacetal base material surface by solvent base, water base or powder 1K paint systems, and the pre-treatment purpose is to increase the described hypocrystalline of described base material or the non-polyacetal resin of amorphous thermoplastic to applying the exposure of paint.

2. the coating polyacetal articles of claim 1, wherein base material comprises 95-98.5wt% polyacetal and 1.5-5wt% hypocrystalline or the non-polyacetal resin of amorphous thermoplastic.

3. the coating polyacetal articles of claim 1, wherein the first polymeric amide amount is 1-2wt%, the second polymeric amide amount is 0.25-1.5wt%.

4. the coating polyacetal articles of claim 1, wherein paint systems comprises thermoplastic polymer, and its second-order transition temperature is lower than 25 ℃.

5. the coating polyacetal articles of claim 1, wherein the described thermoplasticity of the described polyacetal base material of paint or portion of hot plasticity paint is coated with thermosetting varniss or clear coat.

6. the coating polyacetal articles of aforementioned any one claim, wherein said polyacetal does not contain mineral filler.

7. produce the method that applies polyacetal articles for one kind, comprising:

The polyacetal base material of producing by the solidification of molten blend is provided, described blend comprises 90-99.5wt% polyacetal and 0.5-10wt% molecular weight 1,000-50,000 hypocrystalline or the non-polyacetal resin of amorphous thermoplastic, the non-polyacetal resin of wherein said hypocrystalline or amorphous thermoplastic comprises:

The blend of first and second polymeric amide of different molecular weight, wherein said first polymeric amide has the molecular weight than described second polymeric amide big at least 5000, described first polyamide molecular weight is 20,000 to 50,000, the described first polymeric amide amount is 0.5-5wt%, described second polyamide molecular weight is 1,000 to 25,000, the described second polymeric amide amount is 0.1-2.5wt%, and wherein said each polymeric amide has (i) and measures under 105 dyne/cm2 shearing stress down at 200 ℃ and demonstrate less than 50, the melt viscosity of 000 pool, and the amount of wherein said second polymeric amide is equal to or less than first polymeric amide; With

Handle polyacetal base material surface so that apply paint, thereby improve described hypocrystalline or the non-polyacetal resin of amorphous thermoplastic applying the exposure of paint to treat surface; With

Paint on the treat surface of polyacetal base material by solvent base, water base or powder 1K paint systems application of heat plasticity or portion of hot plasticity.

8. the method for claim 7, the surface of wherein handling the polyacetal base material by process for modifying surface, described process for modifying surface is selected from etch, burning, ionization, sand milling, cleaning surfaces and uv light exposure.

9. the method for claim 8, surface wherein by handling the polyacetal base material with the mixed acid bath etch, described mixed acid bath comprises and is selected from sulfuric acid, phosphoric acid, hydrochloric acid and at least three kinds of acid of organic acid.

10. the method for claim 9, wherein mixed acid bath comprises sulfuric acid, phosphoric acid, hydrochloric acid and acetate.

11. the method for claim 7 wherein provides the polyacetal base material by molding, extrusion molding or thermoforming.

12. the method for claim 7 wherein applies coating thermoplastic or portion of hot plasticity paint by dipping, spraying, brushing or powder.

13. the method for claim 7, it comprises that covering the thermoplasticity or the portion of hot plasticity that apply with thermosetting varnish or clear coat paints.

14. the method for claim 7, the wherein said first polymeric amide amount is 1-2wt%, and the described second polymeric amide amount is 0.25-1.5wt%.

15. any one method of claim 7-14, wherein said polyacetal does not contain mineral filler.

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