JPH05501121A - Polyphenylene ether compositions resistant to environmental stress cracking - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Resistant to environmental stress cracking polyphenylene ether composition, The present invention provides good resistance to environmental stress cracking along with good melt flow properties. A novel combination of polyphenylene ether resin and impact-resistant rubber-modified polystyrene with Concerning thermoplastic blends.

Brief description of prior art Polyphenylene ether resins have relatively high melt viscosities and high softening temperatures (typically 20 A high performance, inherently flame retardant engineering thermoplastic with a be. However, these resins have the major drawback of not being easy to melt process. It has long been recognized that there are Polyphenylene ether resin has good moldability and Polystyrene resins, especially butadiene-based elastomers, to improve processability Impact resistance like rubber-modified graft copolymers with styrene grafted onto polymers It has been blended with polystyrene resin. Such blends are for example , Cyzek (Ci!ek) [General Electric Company (Gener US Pat. No. 3,383.435 (19 It was disclosed in 1968).

combination of polyphenylene ether and styrene polymer (especially high-impact polystyrene) Blends have proven to be very useful and are the mainstay of commercial compositions. death However, improvements are needed regarding stress cracking in articles molded from these resin blends. It is rare. Stress cracking is the most frequent failure mode and reduces the service life of molded parts. Determine the upper limit of life. This failure mode occurs because the local stress in the product is extreme. This is when microcracks occur in areas where the stress exceeds the limit stress value. Microcracks propagate This results in macroscopic damage.

Furthermore, in the presence of certain chemicals, fuels, oils, and solvents, critical stress values may be It is known that . Stress cracks induced in this way are called environmental stress cracks (ESC). . As an example, polyurethane foam is used in coated metal plates for plastic refrigerators. ESC caused by fluorochlorocarbon blowing agent remaining in the foam be.

Another situation where ESC is problematic is in automotive applications.

Because ESC is amplified by gasoline and oil, plastic Many applications of polyphenylene ether resins include hindered.

Various means have been explored to overcome ESC. The inventors have already , U.S. Patent Nos. 3,819.761 (1974) and 3,976.725 (1976), in polyblends with polyphenylene ether resins. Improved ESC by using rubber-modified polystyrene with high intrinsic viscosity It has been disclosed that resistance can be achieved. However, such a blur It is difficult to process because of its inherently high viscosity.

Another way to try to overcome ESC is by Lohmeii. e+) [General Electric Co. o, )], U.S. Pat. No. 4,529,761 (1985). By adding sea urchin alkyl sulfonates, de MσnkJ et al. [ General Electric Co. vinyl as taught in U.S. Pat. No. 4,647,594 (1987). Addition of alkyl sulfonate along with aromatic-diene block copolymer Is Rukoto. However, the use of such additional ingredients complicates mixing. This is not desirable.

One object of the present invention is to provide a polyphenylene ether-high impact polystyrene blend. detract from other useful and unique properties of the bond, such as good impact strength and processability. Good melt flow with improved environmental stress cracking resistance without damage By obtaining a polyphenylene ether resin-containing molding composition having be.

The inventor has recently discovered that polyphenylene ether with low intrinsic viscosity and polyphenylene ether with low intrinsic viscosity Polyphenylene ether-polystyrene produced using consistently high polystyrene Renblend provides improved melt flow and improved environmental stress cracking resistance and a wide range of other desirable physical properties. I discovered that.

Summary of the invention The present invention is modified for forming articles that are resistant to environmental stress cracking. Consists of a thermoplastic resin blend with improved flow properties. This blend is mixed together, (a) Polymer having an average intrinsic viscosity of less than about 0.4 (preferably less than about 0°35) from about 5 to about 95 (preferably from about 25 to about 70) weight percent of a phenylene ether resin; (b) a point having an average intrinsic viscosity of greater than about 0.85 (preferably greater than about 0.90); about 95 to about 5 (preferably about 75 to about 30) weight percent of a listyrene resin; Contains. The intrinsic viscosity values listed here were measured in chloroform at 25°C. It is.

In a preferred embodiment of the invention, an impact modifier and/or a haze additive are also present. do.

In the Summary of the Invention above and the Detailed Description below, the critical properties of the ingredients are characterized. Intrinsic viscosity is used instead of molecular weight to describe the polymer. - As is clear to those skilled in the art, intrinsic viscosity and molecular weight are related.

However, while intrinsic viscosity is a property that is measured objectively, molecular weight is is inferred from intrinsic viscosity and other measured properties, and therefore most is a polymer that is not exactly known.

The intrinsic viscosity values listed herein are determined by measurement in chloroform at 25°C. It is what was done.

Detailed description of the invention Polyphenylene ether (oxide) used to prepare the composition of the invention The resin component is a member of a well-known family of resins. Polyphenylene A Examples of tel resins and their manufacturing methods are given in U.S. Patent No. 3,306.874, 3°257.3. No. 57 and No. 3.257,358 (all incorporated herein by reference). ).

In addition, polyphenylene ether resins are (Shu) [General Electric Company (Gene+zl Hec+ric C11, )], U.S. Pat. No. 4,824,887 (1989), column 2, number 40 Also described in line ~ column 5, line 23 (which is incorporated herein by reference) It is. A preferred polyphenylene ether resin is 2,6-dimethylphenol. the intrinsic viscosity previously defined as necessary for the present invention. It falls within the range of

The above polyphenylene ether [also referred to as polyphenylene oxide] is expressed by the following formula: It is a polymer block containing a plurality of repeating structural units having the following structure.

In each of these units I, Ql is independently a halogen, a primary or secondary low alkyl (i.e. alkyl containing up to 7 carbon atoms), phenyl, haloalkyl, aminoalkyl, hydrocarbonoxy, or halohydrocarbonoxy ( However, at least two carbon atoms are halogen atoms, hydrogen, halogen, primary or primary. Secondary lower alkyl, phenyl, haloalkyl, hydrocarbonoxy, or Ql halohydrocarbonoxy as defined for . Suitable primary lower alkyl Examples of groups are methyl, ethyl, n-propyl, n-butyl, isobutyl, n-amino isoamyl, 2-methylbutyl, n-hexyl, 2,3-dimethylbutyl, 2-13- or 4-methylpentyl and the corresponding heptyl group. second class Examples of lower alkyl groups are isopropyl, 5ec-butyl and 3-pentyl. Ru. Any alkyl group is preferably straight chain rather than branched. Each Q1 is alkyl or f? phenyl, especially alkyl of C, most often each Q2 is hydrogen.

Both homopolymer and copolymer polyphenylene ethers are included. suitable The homopolymer is, for example, 2゜6-dimethyl-1,4-phenylene ether monomer. It contains the position. Suitable copolymers include units such as those listed above. For example) 2. 3. 6-) Together with 9-methylene-1,4-phinidine ether unit There is a random copolymer containing Homopolymers as well as many random Copolymers are disclosed in the above patent documents.

Also, structures that alter properties such as molecular weight, melt viscosity and/or impact strength. Also included are polyphenylene ethers containing moieties. Such polymers are It is described in the patent literature, and acrylonitrile and vinyl aromatic compounds can be Vinyl monomers (such as styrene) or polystyrene or elastomers by grafting polymers such as - onto polyphenylene ether. can be manufactured. This product is usually grafted and ungrafted. It contains a part. Other typical polymers are two polyphenylene esters. The hydroxyl group of the ether chain is reacted with a coupling agent using a known method to form hydroxyl. Produce a partial weight polymer containing the reaction product of the group and the coupling agent. It is a coupled polyphenylene ether. As an example of a coupling agent Examples include low molecular weight polycarbonates, quinones, heterocyclic compounds and formal There are 3 types.

Polyphenylene ethers as a broad group can be measured by gel permeation chromatography. The number average molecular weight is approximately 3°000 to 40,000, and the weight average molecular weight is approximately 3°000 to 40,000. is about 20°000~so,ooo. Broadly speaking, its intrinsic viscosity at 25°C is When measured in chloroform, it usually ranges from about 0.1 to 0.7 dl/g. death However, for purposes of the present invention, the viscosity of the polyphenylene ether is less than about 0.4; Preferably it should be less than about 0.35. These values are included in the composition of the present invention. It refers to the inherent viscosity of the entire added polyphenylene ether (PPE).

As will be recognized by those skilled in the polymer compounding industry, there are two types of PPE. Mixtures of grades or batches can be conveniently used. Using such a mixture If the weight average intrinsic viscosity of the mixture is less than the above upper limit for intrinsic viscosity, Is there a need to go lower? Weight average means the weight of the first PPE grade or batch. fraction multiplied by its intrinsic viscosity and the weight of the second PPE grade or batch means the average calculated by adding the coefficient multiplied by its intrinsic viscosity and There is.

Polyphenylene ethers usually contain at least one corresponding monohydroxy aromatic produced by oxidative coupling of group compounds. Particularly useful and easily available items The hydroxyaromatic compound is 2,6-xylenol [i.e., each Q1 is methyl] , each Q2 is hydrogen, and the resulting polymer is poly(2,6-cymethyl- 1.4-phenylene ether)] and 2.3.6-drimethyl Luphenol [i.e. each Q and one Q2 are methyl ■ and the other Q2 is hydrogen].

Various species that facilitate the production of polyphenylene ethers by oxidative coupling Catalytic systems of the following types are known. There are no particular restrictions on the selection of the catalyst, and any known catalyst may be used. Any deviation can also be used. In most cases, such catalysts are copper, manganese or at least one heavy metal compound, such as a compound of cobalt, usually other It is contained in combination with various substances.

Some commonly used useful catalyst systems are those containing copper compounds. the Such catalysts are described, for example, in U.S. Pat. No. 5, No. 3.914.266 and No. 4.028,341 (the present invention is incorporated by reference). (which shall be included in the specification). These are usually cuprous or or cupric ions, halides (i.e. chloride, bromide or iodide). g) A combination of ions and at least one amine.

A catalyst system containing a manganese compound constitutes a second useful part. Generally these are Divalent manganese with anions such as halides, alkoxides or phenoxides It is an alkaline system combined with In most cases manganese is dialkyl amide alkanolamine, alkylene diamine, 0-hydroxy aromatic aldehyde compound, 0-hydroxyazo compound, ω-hydroxyoxime (monomeric and porous remer), 0-hydroxyaryl oxime and β-diketone. It exists as a complex with the above complexing agent and/or chelating agent. moreover , cobalt-containing catalyst systems are also useful. Suitable for polyphenylene ether production Manganese- or cobalt-containing catalyst systems have been disclosed in numerous patents and publications. are well known in the industry.

No. 4,806,297, incorporated herein by reference. with a variety of end groups, including those disclosed in polyphenylene ether can be used. The molecular weight of polyphenylene ether is by generating such terminal groups or by shortening the polymerization. can be kept low.

The polystyrene resin used as a component of the composition of the present invention is commonly used as well as its manufacturing method. well known. These are either styrene itself or used in styrene polymerization. can be prepared from suitable homologues or analogs, particularly compounds of the formula:

Here, R1 and R2 are each a lower alkyl group having 1 to 6 carbon atoms or a lower alkyl group having 1 to 6 carbon atoms. selected from the group consisting of kenyl group and hydrogen, R3, R4, R5 and R6 each represents bromo, chloro, hydrogen, and lower alkyl group having 1 to 6 carbon atoms. or from the group consisting of lower alkenyl groups. Compound of formula (11) Examples include α-methylstyrene, p-methylstyrene, 2,4-dimethyl Styrene, chlorostyrene, bromostyrene, dipromostyrene, tribromos Styrene, p-tert-butylstyrene and p-ethylstyrene. desired If so, use a non-styrenic comonomer such as acrylonitrile or maleic anhydride. A small amount of phosphoric acid can be included.

Further, the polystyrene component of the composition of the present invention may be entirely or partially made up of impact-resistant polystyrene. It is polystyrene modified with rubber, also called listyrene (HIPS). Good too. Such HIPS materials consist of styrenic monomers and preformed rubber. (e.g., polybutadiene, polyisoprene, styrene-butadiene copolymer) ethylene-propylene copolymer, ethylene-propylene-gentarpolymer, ethylene-propylene copolymer, polymer, polyacrylate, etc.). Conventionally, Such HIPS compositions may contain from about 4 to about Contains 30% by weight of rubber component. Manufacturing methods for polystyrene and HIPS components are industry-standard. and many patents and publications, such as U.S. Pat. No. 4,824,887. (incorporated herein by reference). Smell of the present invention The properties required for polystyrene (or HIPS) used as one component in , with an intrinsic viscosity of at least 0.85, preferably greater than about 0.90. be. This corresponds to a fairly high molecular weight. Polystyrene component is impact resistant poly In the case of styrene, the intrinsic viscosity requirement is based on the soluble portion, i.e. essentially styrene. This refers to the part that consists of. Rubber part is cross-linked and used to determine intrinsic viscosity It is often insoluble in the solvent used.

The high intrinsic viscosity polystyrene component of the composition of the present invention is the same as ordinary polystyrene. Although it can be produced by common methods, it is chained to facilitate the production of high intrinsic viscosity resins. The amounts of transfer agents and chain terminators are kept very low or absent.

The means to obtain high molecular weight polystyrene with the required high intrinsic viscosity is well known. No. 3,819,761 and No. 3,9 No. 76.725, incorporated herein by reference.

In one advantageous embodiment of the invention, polystyrene with a requisite high intrinsic viscosity The ingredients are not of the HIPS type. In other words, it has no rubber parts. It is a "crystalline" polystyrene. This is another resin that is also an impact modifier Also used with ingredients. This impact modifier is added in an effective amount (usually a non-rubber from about 1% to about 30% by weight of the polystyrene component. Impact modifier is poly It may also be an elastomeric impact modifier that is compatible with phenylene ether. . Such impact modifiers include the aforementioned rubbers used when manufacturing HIPS. There are a variety of elastomeric copolymers that are nearly identical to elastomeric copolymers. Some other examples are Ruboxylated ethylene-propylene rubber, various alkenes such as styrene olefins or dienes copolymerizable with aromatic compounds (e.g., butadiene). , isoprene, chloroprene, ethylene, propylene and butylene). copolymers and polystyrene through interpenetrating networks, e.g. Core-shell Ella containing a poly(alkyl acrylate) core bonded to the shell It's a streamer. Such core-shell elastomers are described in U.S. Patent No. 4,681. , No. 915. Among the preferred impact modifiers are alkaline An optionally hydrogenated block of an aromatic compound and a diene (usually diblock, triblock or radial teleblock) copolymers, e.g. , by Shell Chemical Company 7 D series and G manufactured under the trademark KRATON. There are a series of block copolymers.

As will be apparent to those skilled in the art, HI containing less than optimal amounts of impact modifiers PS may be supplemented with additional impact modifiers. In general, HIPS impact modifiers, whether added as part of component (b) or separately; is an effective amount (i.e., in the range of about 4 to about 30% by weight of the non-rubber polystyrene component) ) exists.

The blends of the present invention may be combined with other additives known in the plastic compounding industry. It can be further modified by adding . As such additives , fillers (e.g. clay or talc), reinforcements (e.g. glass fiber), other resins. , plasticizers, glidants and other processing aids, stabilizers, colorants, mold release agents, flame retardants agents, antistatic agents, antioxidant agents, ultraviolet blocking agents, etc.

One particularly advantageous embodiment of the invention also comprises effective amounts of flame retardants (a) and (b). It is a subgroup of blends of Conventional technology polyphenylene oxide and styrene polymer Blends consisting of remers, if modified with flame retardants, are If present in amounts exceeding the degree of compatibility, some leaching of the flame retardant will occur (this (which can sometimes exacerbate environmental stress cracking). According to the invention: triaryl phosphate, tert-butylphenyldiphenyl phosphate or phosphoric acid Highly tolerant of flame retardants such as isopropylphenyl diphenyl, yet Even if some seepage occurs, a blend is obtained that is less prone to stress cracking.

The triaryl phosphates mentioned above also function as plasticizers and processing aids. Ru. An effective amount of such flame retardants is about 1-15% by weight of the total composition.

The compositions of the invention may be prepared by any of the conventional means known for incorporating thermoplastic resins. Manufactured by uniformly mixing or blending components (a) and (b), depending on the can. For example, Banbury (Banbur7) mixer, Warner Fra Ipler (Wc+ner　PIleider! ``) In a crosstalk machine like a blender or in an extruder or using a roll mill. Order of addition The order of the The ingredients should be thoroughly blended together. This blending operation is continuous even in patch type. It can also be implemented.

The blended composition can be extruded and, if desired, cut into granules by standard techniques. It can be made into pellets, etc.

This blended composition can be processed by conventional molding, shaping or molding methods well known in the industry. can be further processed by an extrusion process.

The following examples illustrate methods and steps for carrying out the invention and are provided by the inventors. is considered the best mode, but is not intended to be limiting.

Two types of polyphenylene ether (PPO) with different intrinsic viscosities, this type of blend High-impact polystyrene with a typical intrinsic viscosity range commonly used in Two types of crystals with different intrinsic viscosities using HIPS with a very high rubber content for Made from high-impact polystyrene blended with high-performance polystyrene, After blending, by further mixing and extruding with a twin-screw extruder. Created a series of blends. Extruded plastic material is cut and injection molded. A test bar was created. A strain of 1% was applied by a jig, and phosphoric acid was used as the crack-inducing medium. Diphenyl t-butylphenyl fluid [S+aulfer 71] B] was used to conduct the ESC test. Record the time it takes for the crack to become visible. Ta. Flexural modulus was determined according to ASTM test method D-790. Flow length is a spy Table 1 by Larmold method ppo■0.461V' 35 20 20 20 35 35 [F] PPOO, l91V2-15 15 15--HIPS3 65 65 −　−　−　−i+1iiCom HIPS' --30303030PS Dairen - -35-35- (Dylene)08G High MW5 PS Huntman --35-35 (Hunfman) 206 Polyethylene 1.5 +, 5 1.5 1.5 1.5 1.5 Stabilizer 8 (1 ,11(1,80,8G,ll　O,8Q,8 quality Time to crack 42 37 56 17 45 22 (average) 9 Curved jf elastic modulus 1O3123116294293321324 flow length” 23 2 7 27 28 23 24 Note Poly( 2,6-dimethyl-1,4-phenylene ether). general electric General Electric Compxnyl.

It is similar to 5.21, but the intrinsic viscosity is very low (i, V, 0°19). This corresponds to a molecular weight of 800. General Electric Company (General E electric Compan7).

3 Hantsmxn 1897° HIPS with intrinsic viscosity 0.81 0 4 High impact polystyrene with high rubber content. The intrinsic viscosity of its soluble portion is 0.59 ゜ 5 High intrinsic viscosity polystyrene. i, v, approximately 1.1, number average molecular weight approximately 114.6 00, weight average molecular weight approximately 294. 500, gel permeation chromatograph Measured in fees.

6 Medium intrinsic viscosity polystyrene. t, V, o, 9, number average molecular weight approximately 71.7 00, weight average molecular weight approximately 200.000, gel permeation chromatography Measured by ee.

7 Styrene-butadiene-styrene block copolymer.

Shell Chemical Company (Shell Chea+1cxl Campu7).

Stabilizer mixture consisting of tridecyl 8-phosphite, zinc sulfide and zinc oxide.

9 credits worth. Average of two test bars.

"Kpsi. Measured by ASTM D-790.

11 inches. Measured by spiral mold method.

It shows. However, along with the high intrinsic viscosity PS, the low intrinsic viscosity ppo (9) When included, good flowability and good ESC resistance were obtained.

Another series of tests was conducted using HrPS, which has a very high intrinsic viscosity. In this case Force cracking started at 1% strain in mineral spirits. The results are shown in Table 2 below.

Table 2 Example number 7 8 9 Composition (wt%) PPO@0.46IV 50 35 35P P O@0.25 I V2 1 (IPS (regu two) 50 50 -VHMW HIPS'--50 PE51.5 1.5 1.5 Stabilizer 60.8 0.8 0.8 sexual quality Time to crack 6 minutes 10-10-(average) 6 15 seconds 15 minutes Flow length 725.0 28.7 27.7 Note 1 has an intrinsic viscosity of 0.46 and corresponds to a molecular weight of approximately 20.000. Poly(2,6-) manufactured by Genetil Electric Co. dimethyl-p-)unicine ether).

2 Genera with an intrinsic viscosity of 0.25 and corresponding to a molecular weight of approximately s, ooo to 9.000. Polymer manufactured by General Electric Co. (2,6-dimethyl-p-phenylene ether.

3 High impact polystyrene. Huntsman (hn+sman) 1897° on rubber Polybutadiene in a partially grafted styrene homopolymer matrix Contains 10% of type rubber.

Melt index 2.7° Intrinsic viscosity 0.81° 4 Impact resistant polystyrene. Han Hulsman code number T1119° polyester with intrinsic viscosity 0.97 Contains 10.7% polybutadiene type rubber in the Ren matrix.

5 Linear low-density polyethylene used as a processing aid.

6-7 Same as the previous table.

These data show that HIPS, which has a high intrinsic viscosity, is compared with PP0O, which has a very low intrinsic viscosity. When blended, very good against ESC with good flow and impact properties This shows that high resistance can be obtained.

Summary book Forming articles with resistance to environmental stress cracking and good melt flow properties Thermoplastic blend for polyphenylene ether resin with low intrinsic viscosity and polystyrene resin with high intrinsic viscosity. This composition is Additionally, impact modifiers and/or flame retardants may be included.

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Claims (12)

[Claims] (1) Uniformly mixed; (a) a polyphenylene ether resin having an average intrinsic viscosity of less than about 0.4 from about 5 to about 9; 5% by weight, and (b) a polystyrene resin having an average intrinsic viscosity greater than about 0.85. 95 to about 5% by weight with improved melt flow properties and is resistant to environmental stress cracking. Thermoplastic resin blends for molding articles. (2) (a) Polyphenylene ether resin with an average intrinsic viscosity lower than about 0.4 about 2 5 to about 70% by weight, and (b) polystyrene having an average intrinsic viscosity greater than about 0.85. About 75 to about 30% by weight of resin A thermoplastic blend with improved resistance to environmental stress cracking and flow properties. (3) (a) About a polyphenylene ether resin with an average intrinsic viscosity lower than about 0.35 5 to about 95% by weight, and (b) polystyrene having an average intrinsic viscosity greater than about 0.90. About 95% to about 5% by weight of resin A thermoplastic blend with improved resistance to environmental stress cracking and flow properties. (4) The polyphenylene ether resin has formulas, mathematical formulas, chemical formulas, tables, etc. ▼(I) [wherein, in each of the above units, Q1 independently represents a halogen, Primary lower alkyl, secondary lower alkyl, phenyl, haloalkyl, amino noalkyl, hydrocarbonoxy and halohydrocarbonoxy (but at least 2 carbon atoms separating the halogen and oxygen atoms), Q 2 each independently represents hydrogen, halogen, primary lower alkyl, or secondary lower alkyl. defined for Q1, phenyl, haloalkyl, hydrocarbonoxy, or Claim 1, which contains a plurality of repeating structural units of halohydrocarbonoxy such as composition. (5) Each Q1 is an alkyl group having 1 to 4 carbon atoms, and each Q2 is hydrogen. 5. The composition of claim 4. (6) Is the polyphenylene oxide mainly 2,6-dimethylphenol? 2. The composition of claim 1, wherein the composition is derived from. (7) The polyphenylene oxide is mainly 2,6-dimethylphenol and 2,3,6-trimethylphenol. Item 1. The composition according to item 1. 8. The composition of claim 1, further comprising an effective amount of an impact modifier. (9) The polystyrene resin has a soluble portion with an intrinsic viscosity of more than about 0.85. The composition of claim 1, which is impact polystyrene. (10) The polystyrene resin is substantially high-impact polystyrene with a high rubber content. and crystalline polystyrene with high intrinsic viscosity. Claim 1, wherein the weighted average intrinsic viscosity of the organic viscosity is greater than about 0.85. Composition of. (11) The composition of claim 1, further comprising an effective amount of a flame retardant. (12) The composition according to claim 11, wherein the flame retardant is triaryl phosphate.