说个行业乱象：做透明折盒和文具的圈子里，挂着"K胶"在卖的货，价格能差出四成。懂行的一看就知道门道——有些是GPPS里掺了SBS改性，透明度勉强够，抗冲却软塌塌；有些干脆拿普通透明PS充数，做出来的透明片材一折就白痕。真正的K胶（丁苯透明抗冲树脂），透明度能对标PC、PMMA，抗冲却是GPPS和SAN的好几倍。把GPPS改性料当K胶卖，上机一拉伸，片材要么发雾要么脆断。K胶副牌水不浅，今天把话说透。
结论先说：国产K胶副牌能用，但透光率和雾度必须先验，国内能规模化量产丁苯透明树脂的独资厂，巴陵石化是绕不开的一家。
K胶是什么？国产货源为什么只剩一家
K胶化学名叫丁苯透明抗冲树脂，是苯乙烯-丁二烯的透明嵌段共聚物，透明度高、光泽好、抗冲强，无毒易着色，可注塑、吹塑、挤出，也能和GPPS、SAN、PP共混增韧，大量用于透明食品包装、文具玩具、医疗器具外壳、日用透明件。它抗冲强度约是GPPS和SAN的三到五倍，又保持透明，是透明硬料里的"透明抗冲"路线。
国产K胶量产门槛高，长期被菲利浦K-Resin、巴斯夫Styrolux等外资牌号占着高端。国内能规模化做丁苯透明抗冲树脂的独资厂不多，中石化巴陵石化（岳阳，现隶属中石化湖南石油化工体系）是绕不开的主力——它背靠国内规模靠前的锂系阴离子聚合基地，SBC（苯乙烯类热塑性弹性体）体系年产能三十八万吨、含合资合计八十万吨，丁苯透明线就在这个体系里。行业报告口径，巴陵石化在丁苯透明抗冲树脂市场份额居国内前列。其余新进入者多在中试和小批量阶段，还构不成稳定货源。
K胶副牌：透光率和雾度是照妖镜
K胶副牌，是原厂同一牌号体系里出厂检验个别指标小幅偏离的批次。落到K胶上，副牌最常见的差异点集中在四项：透光率偏低、雾度偏大、抗冲强度下降、色相偏黄。
为什么这几项关键？K胶卖的就是"透明加抗冲"，雾度一大，透明折盒和文具就发雾；抗冲强度掉了，透明件一摔就裂。和GPPS掺SBS的假货相比，原厂K胶副牌至少基材是真丁苯透明结构，只是指标小幅偏离；掺料假货连基材都不对。买K胶副牌，先把透光率和雾度验明白。
和回料的区别：K胶回料是透明片材、文具破碎再造，透明结构已经受热破坏，发雾发脆；K胶副牌是原厂原生透明嵌段粒子，只是个别指标小幅偏离。做透明折盒，用副牌是"雾度够不够低"的问题，用回料是"透明发不发乌"的问题。
巴陵石化：国产丁苯透明树脂的主力
巴陵石化在湖南岳阳，是国内规模靠前的锂系阴离子聚合物生产基地之一，SBC体系涵盖SBS、SEBS、SIS、SEPS和丁苯透明线，技术和催化剂水平居世界先进。它的丁苯透明抗冲树脂牌号在透明片材、文具、日用透明件圈有多年流通，央企批次管理规范，透光和抗冲数据齐全。
巴陵K胶副牌料的特点是：丁苯透明线体系成熟，透明级牌号在透明片材和文具方向有量；副牌以雾度和抗冲小幅偏离为主，适合透明折盒、文具、日用透明件等对成本敏感的制品。高端医疗和食品接触认证透明件仍建议正牌。
适用场景：透明折盒片材、文具玩具、日用透明件、食品包装外壳、与GPPS/SAN共混增韧。
K胶副牌避坑指南
第一，透光率和雾度必验。K胶副牌先测这两项，雾度偏大的批次做出来发雾，别上透明折盒和外观件。
第二，别把GPPS掺SBS当K胶。GPPS改性料透明度勉强、抗冲软，和原厂K胶不是一回事，采购时看基材牌号和检测单。
第三，抗冲强度要核。透明件要求摔不裂，副牌抗冲掉档的批次别上受力透明件。
第四，医疗和食品接触认证件别用副牌。有医疗、食品接触要求的透明K胶件必须正牌并保留认证，副牌只用于日用和一般透明制品。
科隆仓库现货｜国产K胶透明片材配套
科隆在宁波仓库常备国产K胶副牌现货，主推品牌为中石化巴陵石化这一国产丁苯透明树脂主力。主要牌号涵盖透明片材级、注塑级多个常用型号，包装分大包装与小包装两种，按透明制品配方备货。
仓库现货通常在5000吨左右：小包副牌备货800-1000吨，箱装副牌备货300-500吨，大包料/吨包料备货3500-3900吨。
供应保障走先测后签：每批K胶副牌料到货先抽测透光率、雾度、抗冲强度三项关键指标，确认透明级可用再签合同；片材厂换料前科隆可先提供小样做透明度和抗冲验证，通过后再批量切料。
选型口诀与案例
国产K胶副牌怎么验？记住四句话：透光雾度先测，别把掺料当真胶，抗冲强度要核，医疗食品件不碰副牌。
襄阳一家做透明塑料折盒和文具的片材厂，原来一直用进口K胶正牌做透明包装盒，每吨成本偏高。今年改用科隆供的巴陵石化K胶副牌透明片材级，先拿小样测透光率和雾度在合格范围，批量挤出后片材透明度和抗冲都达标，成品通过印刷厂套色和跌落测试，每吨原料成本降了近两千元。车间主任说：透明折盒又不是医疗器具，雾度够低、抗冲稳，国产副牌完全顶得上。
Let me share an industry phenomenon: In the transparent folding box and stationery circle, products labeled "K glue" can differ by 40% in price. Anyone in the know knows at a glance—some GPPS are modified with SBS, barely transparent but weak in impact resistance; Some simply use ordinary transparent PS as a substitute, producing transparent sheets that have white marks when folded. Real K glue (styrene-butadiene transparent impact-resistant resin) has transparency comparable to PC and PMMA, but its impact resistance is several times higher than GPPS and SAN. Selling GPPS modified material as K glue, once stretched on the machine, the sheet either fogs up or breaks brittlely. K-glue is a sub-brand, so today I'll explain it thoroughly.
Conclusion First: Domestic K rubber is a sub-brand, but its light transmittance and haze must be tested first. Among domestic wholly-owned factories capable of mass-producing styrene-butadiene transparent resin, Baling Petrochemical is one that cannot be avoided. What is
K rubber? Why is there only one domestic supply
K The chemical name of styrene-butadiene transparent impact-resistant resin is a transparent block copolymer of styrene-butadiene. It has high transparency, good gloss, strong impact resistance, is non-toxic and easily colored, can be injection molded, blow molded, extrusion, and can also be blended with GPPS, SAN, and PP for toughness. It is widely used in transparent food packaging, stationery toys, medical device shells, and daily-use transparent parts. Its impact strength is about three to five times that of GPPS and SAN, while maintaining transparency, representing the "transparent impact resistance" route among transparent hard materials.
Domestic K-glue has high mass production thresholds and has long been dominated by foreign brands like Philips K-Resin and BASF Styrolux. There are few wholly-owned factories in China capable of scaling up styrene-butadiene transparent impact-resistant resin. Sinopec Baling Petrochemical (Yueyang, now part of Sinopec's Hunan petrochemical system) is an unavoidable main force—backed by a leading domestic lithium-based anion polymerization base, the SBC (styrene-based thermoplastic elastomer) system has an annual capacity of 380,000 tons, including joint ventures totaling 800,000 tons, and the styrene-butadiene transparent line is part of this system. According to industry reports, Baling Petrochemical ranks among the top domestic market shares in styrene-butadiene transparent impact-resistant resin. Other new entrants are mostly at pilot and small-batch stages and have yet to establish stable supply sources.
K rubber secondary brands: light transmittance and haze are like mirrors
K secondary rubbers, which are batches within the same original brand's system where some factory inspection indicators slightly deviate. For K glue, the most common differences for secondary brands are four main points: low light transmittance, high haze, reduced impact resistance, and yellowish hue.
Why are these key points? K rubber is sold as "transparent plus impact resistance"; when haze is high, transparent folding boxes and stationery fog up; impact resistance drops, and transparent parts crack with a drop. Compared to counterfeits mixed with GPPS and SBS, the original secondary brand K glue at least has a genuine styrene-butadiene transparent structure, with only slight deviations in the specifications; Fake products with added ingredients don't even have the correct base material. When buying K-glue secondary brands, first check the light transmittance and haze to make sure they are clear. Difference between
and recycled material: K-glue reuse is made from transparent sheets and stationery that have been crushed and remade; the transparent structure has been damaged by heat, becoming foggy and brittle; The secondary brand of K glue is original transparent block particles, with only slight deviations in certain indicators. When making transparent folding boxes, using secondary brands is a matter of "low haze level," while using recycled material is a matter of "whether transparent or not blackened."
Baling Petrochemical: The main domestic producer of styrene-butadiene transparent resin
Baling Petrochemical is located in Yueyang, Hunan, one of the largest lithium-based anion polymer production bases in China. Its SBC system covers SBS, SEBS, SIS, SEPS, and styrene-butadiene transparent wires, with technology and catalyst levels among the world's advanced. Its styrene-butadiene transparent impact-resistant resin grade has been circulating for many years in the fields of transparent sheets, stationery, and daily transparent parts, with standardized batch management by central enterprises and complete data on light transmission and impact resistance. The characteristics of
Baling K Adhesive secondary brand material are: a mature styrene-butadiene transparent wire system, with transparent grade grades in the direction of transparent sheets and stationery; The secondary brand mainly has slight deviations in haze and impact resistance, suitable for transparent folding boxes, stationery, daily transparent parts, and other cost-sensitive products. High-end medical and food-contact certified transparent parts are still recommended for genuine products.
Applicable scenarios: transparent folding box sheets, stationery toys, daily transparent parts, food packaging shells, blended with GPPS/SAN for toughness.
K Rubber Secondary Brand Pitfall Guide
First, light transmittance and haze must be verified. For secondary K glue, test these two items first. For batches with higher haze, avoid misting and do not use transparent folded boxes or appearance parts.
Second, do not mix GPPS with SBS and mistake it for K glue. GPPS modified materials have barely sufficient transparency and impact resistance, which is different from original K glue. Check the base material grade and inspection report when purchasing.
Third, check impact strength. Transparent parts must not crack from drops; for secondary brands with wash-resistant batches, use load-bearing transparent parts.
Fourth, do not use secondary brands for medical and food contact certification parts. Transparent K rubber parts with medical or food contact requirements must be genuine and certified; secondary labels are only for daily use and general transparent products.
Cologne Warehouse Stock | Domestic K-Glue Transparent Sheet Supporting Stock
Cologne maintains domestic K-glue sub-brand stock in the Ningbo warehouse, with Sinopec Baling Petrochemical, the main domestic styrene-butadiene transparent resin brand. Main grades cover transparent sheet grade and injection-molded grade, with packaging available in large and small packaging, stocked according to transparent product formulas.
warehouse stock is usually around 5,000 tons: small sub-brand stock 800-1,000 tons, boxed sub-brand 300-500 tons, large package/ton packaging material stock 3,500-3,900 tons.
Supply Assurance Follows a Testing and Signing Approach: Each batch of K-glue sub-brand material is first sampled for light transmittance, haze, and impact resistance. After confirming transparency grade is usable, contract is signed; Before the sheet mill replaces, Cologne can provide samples for transparency and impact resistance verification, and after passing, batch cutting proceeds.
Selection Mnemonics and Case Studies
How to test domestic K glue sub-brands? Remember these four points: Test light transmittance and haze first; don't mistake additives for real rubber. Stress resistance is important, and medical food parts should not touch sub-brands.
A sheet factory in Xiangyang that makes transparent plastic folding boxes and stationery used imported K glue for genuine brand transparent packaging boxes, which had a relatively high cost per ton. This year, they switched to using Baling Petrochemical K-glue secondary transparent sheets supplied by Cologne. First, small samples were used to measure light transmittance and haze within the qualified range. After mass extrusion, the sheets met both transparency and impact resistance. The finished products passed color registration and drop tests by printing factories, reducing raw material costs by nearly 2,000 yuan per ton. The workshop director said: Transparent folding boxes are not medical instruments; their fog is low and impact resistance stable, and domestic secondary brands can fully compete
