JP6003012B2 - Polyphenylene sulfide resin foam and method for producing the same - Google Patents

Description

  The present invention relates to a polyphenylene sulfide resin foam having a low yellowness and a high whiteness, and having excellent surface appearance, heat insulation, heat resistance, light weight, and moldability, a method for producing the same, and a molded article comprising the polyphenylene sulfide resin foam It is about.

  Polyphenylene sulfide resin (hereinafter sometimes abbreviated as PPS resin) has been put into practical use as a product that makes use of features such as excellent heat resistance, chemical resistance, and electrical insulation.

  For example, as parts for injection molding, automobile parts, precision equipment parts, electrical / electronic parts, etc. that are required to have heat resistance and chemical resistance have been widely used up to now.

  Films are also widely used in film capacitors and chip capacitors for dielectric film applications, circuit boards, insulating substrate applications, motor insulating film applications, and release film applications because of their excellent electrical insulation and flame retardancy. The demand is expanding. In recent years, demands for emphasizing gloss and whiteness and strong demands for weight reduction have been increasing particularly for these applications.

  For example, Patent Document 1 discloses a polyphenylene sulfide resin foam characterized by a crystallinity of 20% or more and an expansion ratio of 2 or more, and these foams make it possible to use conventional polyethylene and polystyrene. It is described that it has the effect of producing a lightweight foam excellent in flame retardancy and low dielectric constant as compared with foams such as polypropylene.

  Further, in film applications where demand is increasing by taking advantage of the low dielectric properties of polyphenylene sulfide resin, studies have been made to suppress product contamination and poor appearance due to volatile components, which was a problem during molding.

  For example, in Patent Document 2, the weight average molecular weight Mw ≧ 10000, the weight average molecular weight Mw / number average molecular weight Mn ≦ 2.5, and the alkali metal content is controlled to be 50 ppm or less to satisfy these demands. It is described.

  Further, not only for film applications but also for various molding applications, studies have been made to reduce the gas components generated from the polyphenylene sulfide resin to suppress the appearance defect.

  For example, in Patent Document 3, an alkaline earth metal is introduced in a range of 200 to 2000 ppm, an inorganic filler is blended, and the temperature-falling crystallization temperature is 210 ° C. or higher, while shortening the molding cycle time, It is described that a resin having a small amount of adhering gas and less fogging by gas can be obtained.

  However, the method described in Patent Document 1 produces a foam that maintains the effects of flame retardancy and low dielectric constant, which are the characteristics of PPS resin, and maintains the heat resistance by defining the range of crystallinity. Although effective, it is insufficient to obtain a foam having an excellent surface appearance, and it is very difficult to obtain a stable white appearance due to the dark color feeling of the PPS resin.

  In the method described in Patent Document 2, the weight average molecular weight Mw is increased and the molecular weight distribution (the definition is the ratio of molecular weight distribution = weight average molecular weight Mw / number average molecular weight Mn) is reduced. The effect of eliminating defects in the film molded product by eliminating the volatile components of the PPS resin film is expected, but it is insufficient as the molding appearance of the foam. However, only inadequate can be obtained. In addition, it is difficult to obtain a product with a white appearance according to this description.

  In addition, the method described in Patent Document 3 is effective in obtaining a PPS resin with an addition of an alkaline earth metal and achieving “low fogging” and “adhesion gas reduction” that are particularly important in lens applications. However, this alone is insufficient to obtain a foam having a good appearance, and the foam does not have a sufficient foaming ratio, and only an insufficient weight can be obtained.

JP-A-7-224185 JP 2008-201885 A JP 2009-275197 A

  In view of the above-mentioned points, the present invention has characteristics such as high whiteness and low yellowness, little unevenness and excellent surface appearance, and has flame retardancy and electrical characteristics that are PPS characteristics. An object of the present invention is to provide a polyphenylene sulfide resin foam having lightness and heat insulating properties, which are the characteristics of the foam, and having excellent moldability, a method for producing the same, and a molded body made of the polyphenylene sulfide resin foam. .

As means for achieving the above object, the present inventors have found that the polyphenylene resin foam of the present invention of the following (1) is useful.
(1) The calcium component is contained in an amount of 80 to 2000 ppm (mass basis) with respect to 100% by mass of the foam, the density of the foam is 50 to 680 kg / m ³ , the L value is 75 or more, and the a value is 0 or less. , b value is 15 or less, polyphenylene sulfide resin foam YI value, characterized in der Rukoto 30 below.

In the polyphenylene sulfide resin foam of the present invention, the following (2) or (3) is preferable.
(2) The polyphenylene sulfide resin foam as described in (1) above, containing 100 to 2000 ppm (by mass) of a calcium component with respect to 100% by mass of the foam.
(3) The weight average molecular weight (Mw) of the polyphenylene sulfide resin (A) constituting the foam and the molecular weight distribution (ratio of weight average molecular weight (Mw) and number average molecular weight (Mn) (Mw / Mn)) The polyphenylene sulfide resin foam according to (1) or (2), wherein the following condition 1 and condition 2 are satisfied.
Condition 1: 50,000 ≦ weight average molecular weight (Mw) ≦ 120,000
Condition 2: 2.6 ≦ molecular weight distribution (Mw / Mn) ≦ 5.5

Moreover, the manufacturing method of the polyphenylene sulfide resin foam of this invention which achieves the objective mentioned above has the structure of the following (4).
(4) The method for producing a polyphenylene sulfide resin foam according to any one of (1) to (3),
Maintaining the polyphenylene sulfide resin (A) sheet in a pressurized inert gas atmosphere and allowing the inert gas (B) to permeate, and the resin (A) sheet impregnated with the inert gas (B) under normal pressure in the step of heating and foaming, characterized in that perforated in this order, a manufacturing method of a polyphenylene sulfide resin foam.

Moreover, in the manufacturing method of this polyphenylene sulfide resin foam of this invention, it is preferable to have the structure of the following (5).
(5) The method for producing a polyphenylene sulfide resin foam according to (4), wherein the inert gas (B) is carbon dioxide gas.

  According to the present invention, it is possible to provide a polyphenylene sulfide resin foam having a low yellowness and a high whiteness, and having excellent surface appearance, heat insulation, heat resistance, light weight, and good moldability.

  According to the present invention, a low-density polyphenylene sulfide resin foam having a low yellowness and a high whiteness and excellent in heat resistance and light weight can be obtained.

  By making use of such characteristics, the polyphenylene sulfide resin foam of the present invention has electrical properties such as heat insulating materials for electronic and electrical parts such as motors that generate heat, sealing materials such as adhesive tapes and packings, and capacitors. It can be suitably used as a molded body of materials, tableware, containers, automobile parts and the like.

  Furthermore, the molded body made of the polyphenylene sulfide resin foam of the present invention is an excellent molded body from the viewpoints of heat resistance, lightness, heat insulation, flame retardancy, and good moldability.

  Hereinafter, the polyphenylene sulfide resin foam of the present invention and the production method thereof will be specifically described.

  Since the polyphenylene sulfide resin foam in the present invention is a foam, it has a density smaller than the original density of the polyphenylene sulfide resin as a characteristic.

That is, the polyphenylene sulfide resin foam of the present invention, the density of the foam, than the low Kuku density 1310kg / m ³ of a general polyphenylene sulfide resin, which is described in the prior literature, in 50~680kg / m ³ It points to something.

As a method for measuring the density, a known method for measuring the density of the foam can be used. For example, the thickness (m) of the product sample cut to a specified area (m ² ) and the mass (kg) of the product sample are measured. And can be calculated by the following density equation.
Density (kg / m ³ ) = sample mass (kg) / (sample area (m ² ) × sample thickness (m))

  Moreover, the confirmation method of a foam can use the well-known method of confirming the cell of a foam, for example, a thickness direction, the vertical direction of a sample area, a horizontal direction with a scanning electron microscope or an optical microscope. If a bubble cell can be confirmed when a cross-sectional photograph is observed in a cross section cut into any of the above, it can be determined that the foam is a foam.

Density of polyphenylene sulfide resin foam of the present invention, 50 (kg / m ³⁾ or more 680 (kg / m ³⁾ or less. In order to reduce the weight and to obtain a foam with low yellowness and high whiteness, from the viewpoint of good density reduction, 50 (kg / m ³ ) or more and less than 500 (kg / m ³ ) is preferable. Furthermore, 50 (kg / m ³ ) or more and less than 300 (kg / m ³ ) are preferable.

  The gas used for the production of the polyphenylene sulfide resin foam of the present invention is not limited. It is possible to contain a gas used at the time of producing the foam as long as the effects of the present invention are not impaired. In the foam, the polyphenylene sulfide resin foam of the present invention preferably contains an inert gas (B) for the purpose of maintaining a stable foamed state without reactivity. Examples of the inert gas (B) include argon, hydrogen, methane, chlorofluorocarbon, carbon dioxide gas, helium, oxygen, nitrogen and the like. Among these, since the gas permeability to the polyphenylene sulfide resin is strong and foaming can be performed at a high magnification, the polyphenylene sulfide resin foam of the present invention more preferably contains carbon dioxide as the inert gas (B).

In order to produce the polyphenylene sulfide resin foam of the present invention, a step of holding a polyphenylene sulfide resin (A) sheet described later in a pressurized inert gas atmosphere and infiltrating the inert gas, and the inert gas ( The manufacturing method which has the process of heating and foaming the resin (A) sheet which permeated B) under normal pressure can be mentioned . Heat medium in the production of polyphenylene sulfide resin foam of the present invention the above mentioned is not particularly limited. Hot air, a heated salt bath, etc. are mentioned.

The method for producing a polyphenylene sulfide resin foam according to the present invention is a step of permeating an inert gas by holding the polyphenylene sulfide resin (A) sheet in a pressurized inert gas atmosphere from the viewpoint of excellent molding processability and foam appearance. And a step of heating and foaming the resin (A) sheet infiltrated with the inert gas (B) under normal pressure in this order . Furthermore, in this production method, an embodiment in which the inert gas (B) is carbon dioxide is particularly preferable.

  When polyphenylene sulfide resin (A) is formed into a sheet of polyphenylene sulfide resin (A), it is possible to melt and mix at a temperature of 300 ° C. or higher and 350 ° C. or lower and perform extrusion molding.

  In the step of holding the polyphenylene sulfide resin (A) sheet in a pressurized inert gas atmosphere and infiltrating the inert gas, the polyphenylene sulfide resin (A) sheet is pressurized to 1 MPa to 20 MPa in a pressurized inert gas (B ) Holding in the atmosphere is preferable because the inert gas can be sufficiently permeated into the polyphenylene sulfide resin (A) sheet.

In the step of heating and foaming the resin (A) sheet infiltrated with the inert gas (B) under normal pressure, heating at 100 ° C. or higher , preferably 250 ° C. or lower is effective for efficient foaming. Good .

  The cell diameter obtained with the polyphenylene sulfide resin foam of the present invention is not particularly limited. Although it is thought that the influence by the magnification of a foam is large, when it cut | disconnects so that the cross section of a thickness direction may be understood normally, it becomes an average bubble diameter of 0.5-100 micrometers or less.

  The density of the polyphenylene sulfide resin foam of the present invention thus obtained is lower than the density of the PPS resin, and it is possible to obtain light weight and heat insulating effects as compared with the unfoamed product.

  The appearance color of the polyphenylene sulfide resin foam of the present invention is characterized by high whiteness. As the whiteness index, numerical values obtained by measuring L value, a value, and b value (hereinafter collectively referred to as Lab) are often used, and the polyphenylene sulfide resin foam of the present invention has an L value of 30. As described above, it is important that the a value is 0 or less and the b value is 20 or less. As Lab, the numerical value measured according to JIS Z8722 (2000) is used. When the L value is lower than 30, the a value is higher than 0, and the b value is higher than 20, a foam with good appearance and high whiteness and low yellowness cannot be obtained.

Moreover, in order to achieve the weight reduction which is the object of the present invention, the lower the density, the easier it is to obtain a foam having high whiteness and low yellowness and a good surface appearance. Polyphenylene sulfide resin foam of the present invention, L value is 75 or more, a value of 0 or less, if the b value is 15 or less, Ru can be granted high gloss appearance.

  The upper limit of the L value of the polyphenylene sulfide resin foam of the present invention is not particularly limited, and the lower limit of the a value and the b value is not particularly limited. As a practically achievable value, the upper limit of the L value is About 99, the lower limit of the a value is about -5, and the lower limit of the b value is about 1.

The polyphenylene sulfide resin foam of the present invention has a L value of 75 or more, an a value of 0 or less, and a b value of 15 or less by containing a calcium component of 80 ppm (mass basis) or more. Holding the sulfide resin (A) sheet in a pressurized inert gas atmosphere and infiltrating the inert gas; and heating and foaming the resin sheet infiltrated with the inert gas (B) under normal pressure; In this manufacturing method, the heating temperature at the time of foaming can be set to 100 ° C. or higher.

The YI value is also used as an indicator of high whiteness of the polyphenylene sulfide resin foam of the present invention, and it is important that the YI value is 30 or less. When the YI value is higher than 30, a foam with good appearance and high whiteness and low yellowness cannot be obtained. The lower limit of the YI value of the polyphenylene sulfide resin foam of the present invention is not particularly limited, but it is considered that the practically achievable value is about 5.

  Further, in order to achieve the weight reduction that is the object of the present invention, that is, the foam having a high whiteness and a low yellowness and having a good surface appearance as the density is further reduced to obtain a foam containing a large amount of gas. It becomes easy to obtain. If the polyphenylene sulfide resin foam of the present invention has a YI value of 30 or less, a high gloss appearance can be imparted, which is preferable.

The method for setting the polyphenylene sulfide resin foam of the present invention to have a YI value of 30 or less includes a calcium component of 80 ppm (mass basis) or more, and the above-mentioned polyphenylene sulfide resin (A) sheet is a pressurized inert gas. Heating at the time of foaming in a manufacturing method having in this order a step of maintaining an atmosphere and infiltrating an inert gas, and a step of heating and foaming the resin sheet infiltrated with the inert gas (B) under normal pressure The method etc. which make temperature 120 degreeC or more can be mentioned.

The PPS resin (A) constituting the polyphenylene sulfide resin foam of the present invention is a polymer having a repeating unit represented by the following structural formula (I). When all the units constituting the PPS resin (A) are 100 mol%, the PPS resin (A) may contain 70 to 100 mol% of repeating units represented by the following structural formula (I). preferable.

The PPS resin (A) is a repeating unit having the following structural formula (II) in which less than 30 mol% of the repeating unit is 100 mol% when all the units constituting the PPS resin (A) are 100 mol%. It is possible to configure.

  The polyphenylene sulfide resin foam of the present invention comprises 50% by mass of polyphenylene sulfide resin (A) in a total of 100% by mass of all the components constituting the foam (excluding gas components such as inert gas (B)). It is preferable to contain 99.99 mass% or less. As a component other than the polyphenylene sulfide resin (A) in the polyphenylene sulfide resin foam, various additives such as a resin other than the polyphenylene sulfide resin and an inorganic filler can be contained as necessary. In addition, the polyphenylene sulfide resin foam of the present invention contains 80% of the polyphenylene sulfide resin (A) in a total of 100% by mass of all components constituting the foam (excluding gas components such as inert gas (B)). More preferably, the content is from 9% by mass to 99.99% by mass.

The PPS resin (A) constituting the polyphenylene sulfide resin foam of the present invention satisfies the following condition 2. Moreover, it is preferable to satisfy the condition 1 . This point will be described.
Condition 1: 50,000 ≦ weight average molecular weight (Mw) ≦ 120,000
Condition 2: 2.6 ≦ molecular weight distribution (Mw / Mn) ≦ 5.5

  The weight average molecular weight Mw of the PPS resin (A) constituting the polyphenylene sulfide resin foam of the present invention is not particularly limited, but preferably 50,000 to 120,000 (measurement method: GPC). . When the weight average molecular weight Mw is 50,000 or more, the moldability is good and it is particularly possible to mold a mold having a large molding draw ratio. On the other hand, it is preferable that the weight average molecular weight Mw is 120,000 or less because the expansion ratio can be easily increased and the density can be lowered and the weight can be reduced. The weight average molecular weight Mw of the PPS resin (A) is more preferably 60,000 to 100,000.

The molecular weight distribution state of the PPS resin (A) constituting the polyphenylene sulfide resin foam of the present invention, that is, the ratio of the weight average molecular weight Mw to the number average molecular weight Mn (Mw / Mn) is 2.6 to 5.5. It is preferred to use. When the molecular weight distribution Mw / Mn is 2.6 or more, the molding condition width is widened, and in particular, molding with a mold having a large molding drawing ratio becomes possible. On the other hand, when the molecular weight distribution Mw / Mn is 5.5 or less, uniform foaming occurs and stable production is possible, and the surface appearance of the foam is improved. More preferably, the molecular weight distribution (Mw / Mn) is from 3.0 to 4.5.

  For the PPS resin (A) constituting the polyphenylene sulfide resin foam of the present invention, the weight average molecular weight Mw is adjusted to 50,000 to 120,000 and the molecular weight distribution (Mw / Mn) is adjusted to 2.6 to 5.5. As a method for carrying out the method, a polymerized and recovered by a known technique or the like can be used.

  For example, a mixture containing at least a polyhalogenated aromatic compound typified by p-dichlorobenzene, an alkali metal sulfide typified by sodium sulfide, and an organic polar solvent typified by N-methyl-2-pyrrolidone is prepared. PPS resin, by-products other than PPS resin, water, halogenated, obtained by heating to 200-290 ° C. range, usually polymerizing by heating for about 0.5-50 hours and then cooling to 220 ° C. or less It can be obtained by recovering the PPS resin from the mixed solution after the polymerization reaction of the alkali metal salt and the organic polar solvent using an eye such as a sieve. At that time, a technique of polymerizing in a branched manner using a crosslinking aid or the like may be carried out.

  About PPS resin (A) which comprises the polyphenylene sulfide resin foam of this invention, the PPS resin superposed | polymerized and collect | recovered may perform a post-process. As described above, the polymerized / recovered PPS resin is likely to contain a low molecular weight PPS resin, a by-product, or impurities, and may be subjected to hot water treatment or washing with an organic solvent. It is known as publicly known.

  When performing hot water treatment, it is as follows. Although there is no restriction | limiting in particular in the hot water used for the hot water process of PPS resin which comprises the foam of this invention, From the point of a cleaning effect, it is preferable that the water to be used is distilled water or deionized water. The hot water temperature is also preferably 90 ° C. or higher.

  When the organic solvent treatment is performed, it is as follows. The organic solvent used for the organic solvent treatment of the PPS resin in the present invention is not particularly limited as long as it does not have an action of decomposing the PPS resin, and N-methyl-2-pyrrolidone, dimethylacetamide, 1, 3 -Dimethylimidazolidinone, piperazinone-containing polar solvents containing nitrogen atoms, polar solvents containing halogen atoms such as methylene chloride, trichloroethylene, perchloroethylene, monochloroethane, dichloroethane, chloroform, chlorobenzene, acetone, methyl ethyl ketone, diethyl ketone, acetophenone And ketone solvents such as Among these, use of N-methyl-2-pyrrolidone, acetone or chloroform is particularly preferable. These organic solvents may be used alone or in combination of two or more. Moreover, it is preferable that the washing | cleaning temperature is normal temperature-200 degreeC from the point of the washing | cleaning effect.

The polyphenylene sulfide resin foam of the present invention contains a calcium component of 80 to 2000 ppm (mass basis) with respect to 100% by mass of the foam.

In order for the polyphenylene sulfide resin foam of the present invention to contain a calcium component, the polyphenylene sulfide resin foam can be obtained by containing a carboxylate containing calcium component, calcium hydroxide, or the like in the polyphenylene sulfide resin foam. When the calcium component is less than 80 ppm (mass basis) with respect to 100% by mass of the foam, it is difficult to obtain a foam having low yellowness and high whiteness. When there are more calcium components than 2000 ppm (mass standard) with respect to 100 mass% of foams, there exists a possibility that the intensity | strength of a molded article falls or a molded article external appearance deteriorates.

  The carboxylate containing a calcium component is not particularly limited. For example, calcium acetate, calcium propionate, calcium benzoate, calcium phthalate, calcium fumarate, calcium maleate and the like can be mentioned. In view of productivity, calcium acetate is considered preferable. Moreover, it is also possible to use two kinds of carboxylic acid containing these calcium components and calcium hydroxide together.

  There are no particular restrictions on the method of incorporating these calcium components into the polyphenylene sulfide resin foam, but there is a method of adding the calcium component in the form of an aqueous solution during or immediately after the polymerization of the polyphenylene sulfide resin, or washing the polyphenylene sulfide resin. In this case, there is a method of washing with an aqueous solution containing a calcium component, but the latter is generally used. The calcium component used in the latter method is not particularly limited, but calcium hydroxide, calcium acetate and the like are preferably used.

  The calcium component as used in the field of this invention refers to what is detected with the following measuring methods. Moreover, the calculation method of content is also demonstrated together as follows.

The platinum dish is washed with pure water, calcined at 700 ° C. for 1 hour, and dried in a desiccator. A value obtained by precisely weighing the platinum dish to 0.1 mg is defined as A (g). Next, about 5 (g) of the polyphenylene sulfide resin foam of the present invention was collected in a platinum dish, and the total amount of the platinum dish and the sample was precisely weighed to 0.1 (mg) with an analytical balance. (G). Thereafter, a platinum dish containing a foam is placed on a stainless steel bat and placed in a high-temperature oven set at 440 ° C. and baked for 5 hours. Thereafter, the oven is raised to 500 ° C. and further baked for 5 hours. After carrying out the firing treatment, after cooling to 300 ° C. or lower, the platinum dish is stored in a desiccator for 12 hours. Thereafter, the platinum dish is taken out of the desiccator and placed in a muffle furnace stable at 538 ° C. and baked for 6 hours. After the treatment, the platinum dish is taken out from the muffle furnace, and it is confirmed that the black carbide is completely removed from the sample. In addition, baking is further implemented when presence of black carbide is recognized even a little. After the completion of firing, the platinum dish is taken out from the muffle furnace and cooled in a desiccator for 30 minutes. Next, 2 ml of pure water: hydrochloric acid (special grade) = 1: 1 (hereinafter referred to as 1: 1 hydrochloric acid) is added to the platinum dish. Then, using a hot plate, a platinum dish containing 1: 1 hydrochloric acid is heated to such an extent that boiling of the solution is confirmed. Stop heating before evaporating to dryness and cool the platinum dish to room temperature. Thereafter, the contents of the platinum dish are divided into several times while being washed with ion-exchanged water, placed in a 50 ml volumetric flask, and aligned with the 50 ml mark of the volumetric flask. Using the sample solution thus adjusted, measurement is carried out using an atomic absorption measurement apparatus with ion-exchanged water as a blank. As a method for determining the concentration value, the calcium component concentration is calculated by a calibration curve created using a standard solution containing the calcium component to be analyzed. If the measured value deviates from the calibration curve, sample solution X (ml) is collected, diluted with ion-exchanged water to Y (ml), and the concentration is adjusted so that it falls within the calibration curve range. A value measured using the sample solution thus adjusted is defined as C (ppm). The calcium component concentration (ppm) is calculated using the above numerical values.
Calcium component concentration [ppm] = C (ppm) / (BA) × 50 × Y / X

  An inorganic filler can be added to the polyphenylene sulfide resin foam of the present invention as long as the characteristics of the invention are not impaired. Specific examples of the inorganic filler include wollastonite, zeolite, mica, kaolin, clay, bentonite, talc, glass beads, glass flakes and the like. Among these, mica, talc, glass beads, and glass flakes are preferable because a foam having a good appearance can be obtained while maintaining higher mechanical strength.

  The polyphenylene sulfide resin foam of the present invention can be formed into a molded body by a molding method such as in-mold foaming, extrusion molding, vacuum molding, stamping molding, compression molding or the like. These molded bodies can be processed into a shape as required by thermal welding, vibration welding, ultrasonic welding, laser welding, or the like.

  The molded product obtained from the polyphenylene sulfide resin foam of the present invention is applied to a predetermined application. For example, electronic and electrical parts such as LED lamps, connectors, switches, capacitors, PC cases, speakers, exhaust gas pipes and pipe covers, intake gas pipes and pipe covers, intake manifolds, reflectors for lamp reflectors, motor insulation It can be exemplified by automobile parts such as plates. Also for film applications, dielectric foam sheets for capacitors and chip capacitors, motor insulation foam sheets, mold release, taking advantage of the electrical insulation and light weight that are the advantages of foams, and the flame resistance that is the advantage of PPS resins It can also be used for foamed sheets, foam tapes to which an adhesive material is applied.

The measurement methods used in Examples and Comparative Examples are as follows.
(1) Foam density (kg / m ³ )
The density is a value measured according to JIS K6767 (1999). The average value calculated | required from the value measured 3 times was described.
(2) Heat molding processability Evaluation was performed based on a molding drawing ratio at the time of vacuum molding. In a vertical cylindrical female cup with a diameter D and a depth H, when the foam is heated and straight molded using a vacuum molding machine, the foam does not break and expands and expands into a cylindrical shape. The comparison was made by comparing the values with the largest H / D values. In addition, the diameter D used the cup of 50 mm, measured the mold drawing ratio in the temperature whose surface temperature of a foam is 240 degreeC, and evaluated it in four steps as follows from the value.
4: Molding ratio is 0.70 or more 3: Molding ratio is 0.50 or more and less than 0.70 2: Molding ratio is 0.40 or more and less than 0.50 1: Molding ratio is less than 0.40 (3 ) Surface appearance The surface state of the obtained foam was evaluated by visual observation and tactile sensation. The state was evaluated in four stages as follows.
4: The surface is smooth and glossy.
3: Although there is a part where the surface is not smooth in the touch feeling, it is not visually recognized.
2: The surface was not smooth when touched, and the surface condition was slightly rough by visual inspection.
1: Irregularities on the surface are confirmed both by touch and by visual observation.
(4) Foam color tone / whiteness (YI value, Lab value)
The color tone and whiteness were measured according to JIS Z8722 (2000). About the surface of the obtained resin foam, the digital yellowness meter (SM color computer) of Suga Test Instruments was used.

  Examples and comparative examples will be described below.

Gel permeation chromatography (GPC) was used for the weight average molecular weight Mw and the number average molecular weight Mn of the polyphenylene sulfide resin (A). The detailed measurement method is as follows.
Device name: SSC-7100 (manufactured by Senshu Chemical)
Column name: GPC3506 (manufactured by Senshu Chemical)
Eluent: 1-chloronaphthalene Detector: Differential refractive index detector Column temperature: 210 ° C (detector temperature is also 210 ° C)
Flow rate: 1.0 (ml / min)

Example 1
Using polyphenylene sulfide resin (A) having a weight average molecular weight Mw of 78,000 and a molecular weight distribution Mw / Mn of 3.8, the calcium component is 100 ppm (mass basis) with respect to 100% by mass of the finally obtained foam. As described above, the product obtained by washing (substituting) the hydrogen end groups of the polyphenylene sulfide resin (A) with an aqueous calcium acetate solution is melt-kneaded in an extruder set at 310 ° C. and extruded into a sheet state. Went. This polyphenylene sulfide resin sheet was placed in a pressure vessel, pressurized to 6 MPa with carbon dioxide as an inert gas (B), and carbon dioxide was permeated into the sheet. The carbon dioxide gas permeation time into the sheet was 72 hours. The sheet taken out from the pressure vessel was continuously supplied to a 200 ° C. foaming furnace so that the foaming time was 1 minute and foamed.

Example 2
Manufacture was carried out in the same manner as in Example 1 except that the foaming temperature was 120 ° C., to obtain a polyphenylene sulfide resin foam.

Example 3
Manufacture was carried out in the same manner as in Example 1 except that the foaming temperature was 100 ° C., to obtain a polyphenylene sulfide resin foam.

Reference example 1
Using polyphenylene sulfide resin (A) having a weight average molecular weight Mw of 110,000 and a molecular weight distribution Mw / Mn of 4.0, a calcium component of 70 ppm (mass basis) is obtained with respect to 100 mass% of the finally obtained foam. Except as described above, production was carried out in the same manner as in Example 1 to obtain a polyphenylene sulfide resin foam.

Example 5
Manufactured in the same manner as in Example 1 except that the polyphenylene sulfide resin (A) having a weight average molecular weight Mw of 78,000 and a molecular weight distribution Mw / Mn of 5.0 was used to obtain a polyphenylene sulfide resin foam.

Reference example 2
Manufacture was performed in the same manner as in Example 1 except that the foaming temperature was 80 ° C., and a polyphenylene sulfide resin foam was obtained.

Example 7
In the same manner as in Example 1, using polyphenylene sulfide resin (A) having a weight average molecular weight Mw of 78,000 and a molecular weight distribution Mw / Mn of 3.8, calcium is finally added to 100% by mass of the foam obtained. The product obtained by washing (substituting) the hydrogen end groups of the polyphenylene sulfide resin (A) with an aqueous calcium acetate solution so as to have an ingredient of 80 ppm (by mass) is melt-kneaded in an extruder set at 300 ° C. The carbon dioxide gas (B) in a pressurized state was injected and dissolved up to 15 (MPa) in the middle, and then the pressure was released from the extruder die and discharged, and the foamed resin was molded into a sheet. Thereafter, it was cooled to obtain a polyphenylene sulfide resin foam.

Example 8
Using polyphenylene sulfide resin (A) having a weight average molecular weight Mw of 47,000 and a molecular weight distribution Mw / Mn of 2.1, a calcium component of 110 ppm (mass basis) is obtained with respect to 100% by mass of the finally obtained foam. A polyphenylene sulfide resin foam was obtained in the same manner as in Example 1 except that the product was obtained by washing (substituting) the polyphenylene sulfide resin (A).

Comparative Example 1
As shown in Table 1, the weight average molecular weight Mw is 110,000, the molecular weight distribution Mw / Mn is 4.0, and the polyphenylene containing no calcium component is washed only with N-methyl-2-pyrrolidone at the time of washing. A polyphenylene sulfide resin foam was obtained in the same manner as in Example 1 except that the sulfide resin was used. Since a polyphenylene sulfide resin not containing a calcium component was used, the calcium component of the obtained foam was 0 ppm (mass basis).

Comparative Example 2
As shown in Table 1, the weight average molecular weight Mw is 110,000, the molecular weight distribution Mw / Mn is 4.0, and the polyphenylene containing no calcium component is washed only with N-methyl-2-pyrrolidone at the time of washing. Except having used sulfide resin, it manufactured like Example 2 and obtained the polyphenylene sulfide resin foam. Since a polyphenylene sulfide resin not containing a calcium component was used, the calcium component of the obtained foam was 0 ppm (mass basis).

Comparative Example 3
As shown in Table 1, the weight average molecular weight Mw is 110,000, the molecular weight distribution Mw / Mn is 4.0, and the polyphenylene containing no calcium component is washed only with N-methyl-2-pyrrolidone at the time of washing. Except having used sulfide resin, it manufactured like Example 3 and obtained the polyphenylene sulfide resin foam. Since a polyphenylene sulfide resin not containing a calcium component was used, the calcium component of the obtained foam was 0 ppm (mass basis).

Comparative Example 4
As in Comparative Example 1, the weight average molecular weight Mw is 110,000, the molecular weight distribution Mw / Mn is 4.0, and the polyphenylene containing no calcium component is washed only with N-methyl-2-pyrrolidone at the time of washing. In the middle of melt-kneading in an extruder set at 305 ° C. using a sulfide resin, carbon dioxide (B) in a pressurized state was injected and dissolved up to 15 (MPa), and then from the extruder die After releasing the pressure and discharging, the foamed resin was molded into a sheet shape and then cooled to obtain a polyphenylene sulfide resin foam. Since a polyphenylene sulfide resin not containing a calcium component was used, the calcium component of the obtained foam was 0 ppm (mass basis).

  The evaluation results for Examples and Comparative Examples are shown in Tables 1 and 2.

  The resin-crosslinked foam of the present invention has low yellowness and high whiteness, and is effective for applications requiring surface appearance, heat insulation, heat resistance, light weight, and good moldability, for example, generates heat. Electrical parts such as motors and other electronic and electrical insulation materials, adhesive tapes, seals such as packing, dielectric foam sheets for capacitors, automotive parts such as tableware, containers, intake manifolds, and lamp reflectors There is a possibility that it will be used for moldings.

Claims (5)

Calcium component is contained in 80 to 2000 ppm (mass basis) with respect to 100% by mass of the foam, the density of the foam is 50 to 680 kg / m ³ , L value is 75 or more, a value is 0 or less, b value Is a polyphenylene sulfide resin foam characterized by having a YI value of 15 or less.   The polyphenylene sulfide resin foam according to claim 1, comprising 100 to 2000 ppm (mass basis) of a calcium component with respect to 100 mass% of the foam. The weight average molecular weight (Mw) of the polyphenylene sulfide resin (A) constituting the foam and the molecular weight distribution (ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn)) are as follows: The polyphenylene sulfide resin foam according to claim 1, wherein 1 and condition 2 are satisfied.
Condition 1: 50,000 ≦ weight average molecular weight (Mw) ≦ 120,000
Condition 2: 2.6 ≦ molecular weight distribution (Mw / Mn) ≦ 5.5   It is a manufacturing method of the polyphenylene sulfide resin foam in any one of Claims 1-3, Comprising: The said polyphenylene sulfide resin (A) sheet | seat is hold | maintained in a pressurized inert gas atmosphere, and inert gas (B) is carried out. Production of a polyphenylene sulfide resin foam characterized by comprising a step of permeating and a step of heating and foaming the resin (A) sheet impregnated with the inert gas (B) under normal pressure in this order Method.   The method for producing a polyphenylene sulfide resin foam according to claim 4, wherein the inert gas (B) is carbon dioxide gas.