农用地膜和棚膜到底用不用改性 PP？先说结论：农膜本体的主力基材是 PE 与 EVA，PP 真正站的位置是农用膜材周边件（防虫网、遮阳网、复合防水膜、育秧载体）。这篇把农用场景的耐候、增韧、增透三条线拆开，并讲清哪类件不该用改性 PP。
"膜用了不到一季就发脆，一扯就破。"
"棚膜不到两年透光率就掉下来，冬天保温明显不够。"
这是我被问到农膜材料时，两类客户原话。第一条是地膜/覆盖膜的典型失效——光氧老化把分子链打断，力学先塌；第二条是棚膜的典型失效——透光与外观随老化劣化，保温跟着掉。两条失效看着像"料不行"，但根因常常不在基材本身，在耐候体系和增韧体系配得对不对。
但开写前必须先讲清一件容易踩坑的事：农膜这个领域，改性 PP 不是主角。
一、先说边界：农膜本体的主力基材是 PE 与 EVA，改性 PP 站的是"农用膜材周边件"
农膜材料里，地膜和棚膜本体的主流基材是 PE（LDPE/LLDPE）和 EVA，不是 PP。把这件事讲在前面，后面的选型才不会跑偏。
| 农用场景 | 当前主流基材 | PP 的真实角色 |
|---|
| 地膜（地面覆盖膜） | LDPE / LLDPE（GB 13735-2017 明确为聚乙烯） | 不直接做地膜本体；做地膜加强筋、捆扎固定件 |
| 棚膜（大棚覆盖膜） | PE 耐老化膜、EVA 功能膜（GB/T 4455-2019、GB/T 20202-2019） | 不直接做高透棚膜本体；做棚室绳网、压膜线、内保温幕边 |
| 防虫网 / 遮阳网 / 防风网 | PE 或 PP 挤出/编织网，加抗 UV | PP 是这条线的常见基材之一 |
| 农用防水/复合衬垫 | PP-PE 复合膜、PE 土工膜 | PP 作为复合层或增强层参与 |
| 育苗覆盖、育秧载体 | PP 纺粘非织造布、PP 育秧盘 | PP 是这类制品的常用基材 |
文字版结论：农膜本体（地膜/棚膜）的耐候、透光、柔软性要求是按 PE/EVA 体系优化的，改性 PP 在这里不占优。PP 真正能接的，是"农用膜材周边件"——防虫网、遮阳网、复合防水膜、育秧载体、压膜线这类。 所以本篇主线放在：这些农用膜材类制品，耐候与增韧怎么配。把 PP 硬说成农膜主流，既不专业也过不了原创。
二、工况六维拆解：农用膜材类制品要扛的是日晒、风载与农药熏蒸
把"农用膜材周边件"当成一个件来拆工况，六个维度都得给数字，方向才立得稳。
| 维度 | 农用场景的实际工况 | 对材料的要求 |
|---|
| 温度 | 夏季棚内/膜面可达 50-70℃；北方冬季户外可到 −20℃ 以下；昼夜与季节温差大 | 耐热氧老化 + 低温不脆断，两条都要 |
| 载荷 | 风载（台风/阵风掀扯）、雨雪堆积、张紧应力、作物攀附拉力 | 拉伸与撕裂强度、节点不脱散 |
| 介质 | 紫外线（全年累积）、雨水、农药喷洒、硫磺熏蒸、棚内高湿氨气 | 抗 UV + 耐农药/熏蒸后的性能保留 |
| 寿命 | 防虫网/遮阳网常按 2-5 年设计；地膜加强筋按一季到一年 | 老化后力学保留率是硬线 |
| 外观 | 遮阳网要控遮光率（30-90% 可调）；部分件要色稳不褪 | 透光/遮光按件定，色差可控 |
| 合规 | 涉及食品接触（育秧/采后）走 GB 4806；降解类不得含 PP/PE 烯烃 | 按用途定合规线 |
六个维度里，介质（紫外线+农药/硫磺）和寿命（老化保留率）是两道最硬的线。农用件最容易被忽略的介质是硫磺熏蒸和酸性农药——这一点后面"敢否定"那段会展开。
一个内行细节：PP 的叔碳原子对紫外光极敏感，UV 光子能量刚好够打断 PP 主链 C-C 键，引发链断裂（chain scission），宏观表现就是发脆、粉化、开裂。所以户外 PP 不加稳定体系，等于裸奔。 但加了什么、加多少、有没有被农药抵消，才是真问题。
三、材料路线对比：耐候体系、增韧体系，以及与 PE 基农膜的分工
农用膜材类制品的改性 PP，主线是两条体系并列，再加一条与 PE 基农膜的分工边界。只做分工陈述，不下"谁更好"的结论。
| 路线 | 拿到什么 | 付出的代价 | 适用件 |
|---|
| 耐候体系（炭黑 2-2.5% 屏蔽 + HALS 自由基清除 + 可选 UV 吸收剂） | 抗 UV 老化、深色件寿命显著拉长 | 炭黑只护深色，浅色/透明件无效；分散不好反而成应力点 | 防虫网、遮阳网、压膜线、黑色复合层 |
| 增韧体系（EVA / POE / 弹性体复配） | 低温不发脆、抗冲击与抗撕裂提升 | 加多了拉伸强度与刚性掉，膜变软下垂、张不紧 | 北方冬季件、需耐撕裂的网/绳 |
| 与 PE 基农膜分工 | PE/EVA 管高透高柔的覆盖膜本体 | PP 管结构/绳网/复合增强类周边件 | 按"覆盖"还是"结构/防护"分工 |
三条线不冲突。耐候管"老得慢"，增韧管"撞不破/扯不烂"，PE/EVA 管"盖得透、贴得柔"。 一个农用件要同时满足，先排优先级：是怕晒先破，还是怕风先裂，还是既要透又要韧——这三件事对拉，不可能一把全抓。
四、★ 选型判据表：从老化后力学保留率到炭黑含量，逐项带验证方法
下面这张表是全篇最该收藏的部分。注意第三列"验证方法·标准号"——选型卡住往往不是"看哪个指标"，是"拿什么测、测到多少算过"。
| 指标 | 门限值（典型） | 验证方法 · 标准号 | 常见失效 | 通行解法 |
|---|
| 老化后力学保留率 | 地膜 I 类耐老化：纵向断裂标称应变保留率 ≥50%；棚膜类人工老化后拉伸强度保留率 ≥70%、断裂伸长率 ≥70% | 人工加速老化 GB/T 16422.2（氙弧灯）/ GB/T 16422.3（荧光 UV），测前后拉伸对比 | 户外用一两年发脆、一扯就破 | 耐候体系加量 + 分散控制 |
| 炭黑含量 | ≥2.0%（深色户外聚烯烃通用量化抓手） | 按 JT/T 1432.1-2022 土工格栅 A 级口径借用；炭黑含量检测 | 浅色件靠炭黑无效；深色件炭黑团聚先破 | 炭黑粒径小、分散匀；浅色件改 HALS+UV 吸收剂 |
| 抗 UV 强度保持率 | 户外聚烯烃参照 ≥90%（A 级土工格栅口径） | JT/T 1432.1-2022 | 强度随日照快速衰减 | HALS + 炭黑协同 |
| 低温冲击 / 低温拉伸 | 按地域定：−20℃ 下不断裂、拉伸保持 | GB/T 1040.3（薄膜）/ GB/T 1043.1（冲击） | 北方冬季网/绳脆断 | EVA/POE 增韧复配 |
| 透光率与雾度（若涉棚室幕） | 透光率按件定（棚膜耐老化膜 ≥80%）；雾度按遮光需求 | GB/T 2410-2008 | 透光衰减、黄变 | 浅色/透明件走 HALS 体系，不靠炭黑 |
| 耐农药 / 硫磺熏蒸后性能保留 | 项 + 变化门限 + 方法（行业按暴露后力学保留对比） | 模拟喷洒/熏蒸后做拉伸与外观对比（B 级行业方法） | HALS 被硫磺/酸性农药失活，寿命骤降 | 用农药耐受型 HALS，或降低暴露 |
文字版结论：这张表里有三个"抓手"值得记住——炭黑 ≥2.0% 是深色户外件的量化底线（借用 A 级土工格栅口径），老化后力学保留率是寿命的硬判据，耐农药/熏蒸保留率是最容易被漏掉的一项。 后两项没有统一强制数字的行业门槛，但凡是农药/硫磺使用频繁的棚室周边件，必须单列验证，否则现场寿命会和你实验室测的差出档次。
五、常见失效与根因：只靠炭黑做耐候是片面的，增韧加多了膜会软塌
失效一：只加炭黑做耐候，浅色件照样先破。 炭黑是物理屏蔽，挡 UV 很有效，但只对深色/黑色件有效。浅色、绿色、透明农用件加炭黑要么遮光变色、要么干脆没用。更要命的是，炭黑分散不好时，团聚点本身就是应力集中源，膜最先从这些点裂开——耐候没做成，反而埋了破裂种子。
失效二：增韧剂加多了，膜变软下垂、张不紧。 这是农用膜材最容易犯的错。EVA/POE 加进去，柔韧和低温抗冲上去了，但拉伸强度和刚性同步掉，网/膜失去挺度，张紧后下坠、风一吹就拍打磨损。不是加得越多越好，是按地域和载荷配平。
失效三：HALS 被农药和硫磺熏蒸悄悄干掉。 这是农用场景专属的内行坑。HALS（受阻胺光稳定剂）是清除自由基的，但它会被硫磺熏蒸、酸性农药里的含硫/卤素化合物快速失活。棚室里 regularly 打药、熏棚的件，普通 HALS 撑不了标称寿命。解决方向是农药耐受型 HALS，或降低件对熏蒸的直接暴露。
失效四：老化后力学保留率没测，只看了初始强度。 初始拉伸很强，不代表两年后还强。农用地膜类件若只验出厂强度、不验老化后保留率，现场一季就破的概率很高。判据选错，后面全白做。
六、验证顺序：先外观透光，再老化后力学，不过就退回上一级
这一段同行很少写，但它是换料能不能省钱的关键。顺序错了，问题会在最后一步集中爆出来。
`
① 外观与透光（若涉及棚室幕/遮光网）
看色差、遮光率、雾度是否在门限内
↓ 这一步不过，后面不用做
② 老化后力学保留率
人工加速老化（GB/T 16422.2 / 16422.3）→ 测拉伸/撕裂保留率
↓ 这一关不过，件直接用不住，退回配方
③ 低温性能
−20℃（或当地极值）下拉伸与冲击，试样状态按标准定
↓ 不过，退回增韧体系配平
④ 耐农药 / 耐熏蒸
模拟喷洒/熏蒸后做力学与外观对比
↓ 不过，退回稳定剂体系（换农药耐受型 HALS）
⑤ 整幅张紧与风载试装
上机张紧、模拟风载拍打
↓ 不过，退回取向/收缩/收卷参数
`
每一步都有明确的"不过就退回上一级"判据。最常见的错误是跳过 ② 和 ④ 直接进 ⑤——用成品去判断耐候，等现场一季破了才发现是老化保留率没过，成本已经花出去。
文字版结论：验证顺序是 外观/透光 → 老化保留率 → 低温 → 耐农药 → 试装。老化保留率和耐农药这两关必须放在试装之前，因为它们是"件能不能活过一季"的决定项，过了再谈成型与装配，才不会白花试产费。
七、反向诚实段：超高透光、超长寿命或鲜食直接接触时，这个件不该用改性 PP
前面讲"怎么做"，这里讲"什么时候别做"。这一段对选型的价值最高。
| 出现的情况 | 为什么改性 PP 不合适 | 该往哪走 |
|---|
| 要求超高透光（高档连栋温室、高光效作物） | PP 光学与柔软性不是这类覆盖膜本体的优化方向，主流是高透 PE/EVA 系 | 走 EVA / PO 系长效高透棚膜 |
| 要求超长寿命（5 年以上） 长效农膜 | 长效覆盖膜本体靠 PE/EVA 多层共挤体系，PP 不做覆盖膜本体 | PE/EVA 多层共挤长效膜 |
| 食品直接接触的鲜食包装/采后 | 这类走食品级 PE，按 GB 4806 食品接触合规；PP 也不是覆盖膜主流 | 食品级 PE 体系，过 GB 4806 |
| 要求全生物降解地膜 | GB/T 35795-2017 降解膜不得含聚乙烯、聚丙烯等烯烃类原料 | 全生物降解地膜（脂肪族聚酯类） |
规律很清楚：凡是"高透覆盖膜本体、超长寿命覆盖膜、鲜食直接接触、全降解"这几类，改性 PP 都不该硬撑。 遇到这种需求，做法是先把边界讲清，再谈周边件能不能接——硬接下来的单子，最后都要用返工还回去。
八、换料风险清单：膜类制品的成型窗口与管材注塑完全不同
决定试改性 PP 做农用膜材类制品之前，这张表建议先过一遍。客户的真实顾虑往往不是性能，是"我现在的工艺要不要改"。
| 要动的项 | 需要确认什么 | 不做会怎样 |
|---|
| 口模温度与熔体温度 | 膜/网挤出对温度窗口敏感，PP 与 PE 区间不同 | 断条、晶点、厚度不均 |
| 牵引与冷却 | 膜类靠牵伸定取向，冷却速率决定结晶与收缩 | 厚薄差、收缩不稳、卷不齐 |
| 收卷张力 | 膜/网收卷张力不均会拉伸变形、层间粘连 | 松边、暴筋、上机跑偏 |
| 取向与收缩 | 膜类制品取向方向强度高、垂直方向低，收缩各向异性 | 张紧后畸变、接缝处起皱开裂 |
| 色差 | 深色件炭黑分散、浅色件色母批次要先定色板 | 批次色差争议、遮光率漂移 |
| 验证顺序 | 外观/透光 → 老化保留率 → 低温 → 耐农药 → 试装 | 风险全部压到最后一步集中爆发 |
文字版结论：膜类制品的成型窗口和管材、注塑完全不同——它最该先谈的是"取向与收缩"和"收卷张力"这两件事，而不是模具收缩率。跳过老化与耐农药验证直接试装，等于把寿命风险留到现场一季后才暴露。
九、一页纸汇报对照表：场景、路线、关键指标、验证标准、需先确认的条件
| 场景 | 推荐路线 | 关键指标 | 验证标准 | 需先确认的条件 |
|---|
| 农用防虫网 / 遮阳网 | 耐候 PP（炭黑/HALS）+ 按地域增韧 | 老化保留率、遮光率、撕裂强度 | GB/T 16422.2/16422.3；JT/T 1432.1-2022（炭黑口径） | 颜色（深/浅）、当地紫外线强度、是否定期打药熏棚 |
| 棚室压膜线 / 捆扎绳 | 耐候 + 增韧 PP | 拉伸强度、低温不断、抗 UV | GB/T 1040.3；GB/T 16422 系列 | 张紧方式、最低使用温度 |
| PP-PE 复合农用防水膜 | PP 增强层 + PE 阻水层 | 拉伸、剥离、老化保留 | GB/T 16422 系列；复合层测试 | 介质（水池/灌溉）、是否接触作物 |
| 育秧盘 / 育苗载体 | 食品接触级耐候 PP | 刚性、耐候、合规 | GB 4806（若接触）；GB/T 16422 | 是否直接接触种苗/采后 |
文字版结论：这张表的作用是让技术员能把结论直接往上报，不必重新组织语言。判断标准只有一条——客户拿这张表，能不能在一次会议里把材料方向定下来。 定不下来的，往往是"当地紫外线多强、打不打硫磺"这两项没给。
十、这个件上最容易出问题的，往往不是料本身
农用膜材类制品最常见的早期失效，不是初始强度不够，是户外用了一两季之后发脆、撕裂、色变。公开资料里反复强调的一点：PP 的叔碳链对紫外极敏感，不加稳定体系，户外寿命以季度计；加了炭黑（约 2-2.5%）或 HALS（活性约 0.5%-2.5%），寿命才能拉到数年量级。
材料要求的门槛，按件分两类：深色结构/绳网件看炭黑含量（≥2.0% 是户外聚烯烃的通用量化抓手）和抗 UV 强度保持率（参照 A 级土工格栅 ≥90% 口径）；浅色/遮光可调件不能靠炭黑，要走 HALS + UV 吸收剂体系，并额外验证农药/硫磺熏蒸后的保留率——因为普通 HALS 会被含硫/卤素农药悄悄失活。
行业通行的做法是把耐候体系（炭黑/HALS/UV 吸收剂）和增韧体系（EVA/POE）按地域与载荷配平，而不是单加一项。这一步配不平，现场要么先破、要么先软。
宁波市科隆新材料有限公司在这个方向上常供的是改性聚丙烯（PP）粒子里的耐候与增韧方向：按农用件的暴露环境（紫外线强度、是否打药熏棚、最低使用温度）给到对应的基材档位与稳定剂/增韧体系，主要用来解决上面说的"户外一两季就发脆"和"增韧加多了膜软塌"这两件事；配方按件的工况调，可以配合做小样比对与老化验证，多品种小批量的农用件需求也能接。
| 工况 | 关键判据 | 科隆常规供应 |
|---|
| 农用防虫网 / 遮阳网 | 老化后力学保留率；浅色件走 HALS 体系 | 耐候改性 PP，按暴露环境配稳定剂 |
| 棚室压膜线 / 捆扎绳 | 低温不断、抗 UV | 耐候 + 增韧 PP 方向 |
| 育秧盘 / 育苗载体 | 食品接触合规、耐候 | 食品接触级耐候 PP 方向 |
想提醒一句：农用件出问题，最常见的错法是先换料。发脆、色变、撕裂——每一条的原因都不止一个，可能是稳定剂体系没配平，可能是打药把 HALS 干掉，也可能是增韧加过量导致软塌。先定位，再换料；顺序反了，往往换了几轮还在原地。
常见问答
问：农膜本体（地膜/棚膜）能不能直接用 PP 做？
答：主流不是。地膜标准 GB 13735-2017 明确基材是聚乙烯，棚膜是 PE（GB/T 4455-2019）与 EVA（GB/T 20202-2019）体系。PP 更适合做农用膜材周边件——防虫网、遮阳网、压膜线、复合防水膜、育秧载体这类。覆盖膜本体要高透高柔，那个方向 PP 不占优。
问：浅色遮阳网加炭黑做耐候行不行？
答：不行，或者说不划算。炭黑是物理屏蔽，只护深色/黑色件；浅色件加炭黑要么变色遮光率漂移、要么根本没用。浅色件该走 HALS + UV 吸收剂体系，并且要单独验证农药/硫磺熏蒸后的保留率。
问：增韧是不是加越多越抗造？
答：不是。EVA/POE 加多了柔韧和低温抗冲上去了，但拉伸强度和刚性同步掉，膜/网会变软下垂、张不紧、风一吹就拍打磨损。按地域和载荷配平才是正解，北方冬季件才需要把增韧往上提。
问：打药、熏棚会不会把耐候做白做？
答：会，而且这是农用件最容易漏的一项。普通 HALS 会被硫磺熏蒸、酸性农药里的含硫/卤素化合物快速失活，现场寿命会比实验室测的短一截。农药/硫磺使用频繁的棚室周边件，必须单列耐农药/熏蒸验证，并考虑农药耐受型 HALS。
关于我们
我们站在树脂厂和注塑厂之间。
上一格是石化和聚合，下一格是模具和机台。中间这一段最像翻译——把树脂的指标翻译成件的性能，把件的要求翻译回料的方向。
宁波市科隆新材料有限公司，自产改性聚丙烯（PP）造粒，覆盖均聚 / 无规共聚 / 抗冲共聚三档基材，以及填充、玻纤增强、增韧、阻燃、低气味低 VOC、耐候、免喷涂耐划伤等改性方向；兼营各大石化厂 PP 树脂、副牌料与大包料。
Do agricultural mulch films and greenhouse films really need modified PP? To start with the conclusion: the main materials for agricultural films are PE and EVA, while PP primarily serves in peripheral agricultural film components (insect nets, shade nets, composite waterproof films, seedling carriers). This article separates the three aspects of agricultural applications—weather resistance, toughness enhancement, and transparency enhancement—and explains which components should not use modified PP.
The film became brittle in less than a season and tore as soon as it was pulled.
The greenhouse film's light transmittance dropped in less than two years, and the insulation in winter is obviously insufficient.
These are the exact words from two types of customers when I was asked about agricultural film materials. The first one is a typical failure of mulching/cover films — photo-oxidative aging breaks the molecular chains, and the mechanical properties collapse first; the second one is a typical failure of greenhouse films — light transmission and appearance deteriorate with aging, followed by a loss of insulation. These two failures seem like 'bad material,' but the root cause is often not in the base material itself, but in whether the weather-resistant system and toughening system are properly matched.
But before starting to write, one must first clarify a pitfall-prone matter: in the field of agricultural film, modified PP is not the main player.
1. First, let's talk about the boundaries: the main base materials of agricultural films are PE and EVA, while modified PP serves as 'peripheral components of agricultural film materials'
In agricultural film materials, the mainstream substrates for mulch film and greenhouse film are PE (LDPE/LLDPE) and EVA, not PP. Mentioning this upfront will prevent the subsequent selection from going off track.
| Agricultural scenarios | Current mainstream substrates | The True Role of PP |
|---|
| Mulch film (ground cover film) | LDPE / LLDPE (GB 13735-2017 clearly defined as polyethylene) | Do not make the mulch itself; make the mulch reinforcement ribs and binding fixtures. |
| Greenhouse film (greenhouse covering film) | PE anti-aging film, EVA functional film (GB/T 4455-2019, GB/T 20202-2019) | Do not directly make the main high-transmittance greenhouse film; make the greenhouse ropes and nets, film pressing lines, and inner thermal curtain edges |
| Insect Screen / Sunshade Net / Windbreak Net | PE or PP extruded/braided mesh, with UV resistance | PP is one of the common base materials of this line |
| Agricultural Waterproof/Composite Liner | PP-PE composite film, PE geomembrane | PP participates as a composite layer or reinforcement layer |
| Seedling covering, seedling carrier | PP spunbond non-woven fabric, PP seedling tray | PP is the common base material for this type of product |
Textual conclusion: The weather resistance, light transmission, and flexibility requirements of agricultural films (mulch film/greenhouse film) are optimized based on the PE/EVA system, and modified PP is not advantageous here. PP can truly be applied to 'peripheral agricultural film materials'—such as insect nets, shade nets, composite waterproof films, seedling carriers, and film pressing lines. Therefore, the main focus of this article is: how to match weather resistance and toughness in these agricultural film products. Forcing PP to be called the mainstream for agricultural films is neither professional nor acceptable in terms of originality.
2. Six-dimensional analysis of working conditions: Agricultural film products have to withstand sun exposure, wind load, and pesticide fumigation.
Treat the 'agricultural film peripheral parts' as a single component when analyzing the working condition; you need to provide numbers for all six dimensions for the orientation to stand steadily.
| Dimension | Actual working conditions in agricultural scenarios | Requirements for the materials |
|---|
| Temperature | In summer, the temperature inside the shed/under the film can reach 50-70°C; in the north, winter outdoor temperatures can drop below −20°C; there are large temperature differences between day and night and between seasons. | Heat and oxygen aging resistance, not brittle at low temperatures, both are required |
| Load | Wind load (typhoon/gust tearing), accumulation of rain and snow, tensile stress, crop climbing force | Stretching and tearing strength, nodes do not come apart |
| Medium | Ultraviolet rays (year-round accumulation), rainfall, pesticide spraying, sulfur fumigation, high humidity and ammonia inside the greenhouse | UV resistant Performance retention after pesticide/fumigation |
| Lifespan | Insect-proof nets/shading nets are usually designed for 2-5 years; ground film reinforcement ribs are for one season to one year. | The mechanical retention rate after aging is the hard line |
| Appearance | The sunshade net should control the shading rate (adjustable from 30-90%); some parts need color stability and should not fade. | Translucent/opaque is priced per piece, color difference is controllable |
| Compliance | For food contact (seedling raising/post-harvest), follow GB 4806; degradable types must not contain PP/PE olefins | Determine compliance lines according to usage |
Among the six dimensions, the medium (UV, pesticides/sulfur) and lifespan (aging retention rate) are the two toughest lines. The medium most easily overlooked in agricultural components is sulfur fumigation and acidic pesticides — this point will be elaborated in the later 'dare to deny' section.
An insider detail: The tertiary carbon atom in PP is extremely sensitive to ultraviolet light, and the energy of UV photons is just enough to break the C-C bonds in the PP main chain, causing chain scission. The macroscopic manifestations are brittleness, chalking, and cracking. So outdoor PP without a stabilization system is essentially exposed. But what is added, how much is added, and whether it is counteracted by pesticides is the real issue.
3. Comparison of material routes: weathering-resistant system, toughened system, and division of labor with PE-based agricultural films
Modified PP for agricultural film products mainly follows two parallel systems, plus an additional one delineating the division of roles with PE-based agricultural film. Only the division of roles is stated, without drawing any conclusion about 'which is better'.
| Route | Get what | The price paid | Applicable parts |
|---|
| Weathering system (carbon black 2-2.5% shielding, HALS radical scavenger, optional UV absorber) | UV-resistant aging, significantly extended lifespan of dark-colored parts | Carbon black only protects dark colors; it is ineffective for light-colored/transparent parts. Poor dispersion can instead create stress points. | Insect-proof net, shade net, film-pressing line, black composite layer |
| Toughening system (EVA / POE / elastomer blend) | Does not become brittle at low temperatures, improved impact and tear resistance | Increasing it further causes a drop in tensile strength and rigidity, making the film soft, saggy, and unable to stretch tightly. | Northern winter items, nets/ropes that need to be tear-resistant |
| Division of labor with PE greenhouse film | PE/EVA pipe high transparency and high flexibility covering film body | PP pipe structures/rope nets/composite reinforcement peripheral parts | Based on 'coverage' or 'structure/protection' division of labor |
The three lines do not conflict. Weather-resistant pipes 'age slowly,' toughened pipes 'cannot be broken or torn,' PE/EVA pipes 'are transparent and flexible.' For an agricultural part that needs to meet all these criteria, first prioritize: is it more important to prevent breaking from sun exposure, or cracking from wind, or needing both transparency and toughness—these three aspects pull in different directions, it's impossible to achieve all at once.
4. ★ Selection Criteria Table: From post-aging mechanical retention to carbon black content, item-by-item with validation methods
The table below is the part most worth keeping in the entire text. Pay attention to the third column 'Verification Method · Standard Number' — getting stuck in selecting components is often not about 'which indicator to look at,' but 'what to use to measure it and how much counts as passing'.
| Indicator | Threshold Value (Typical) | Verification Method · Standard Number | Common Failures | Common solution |
|---|
| Mechanical retention rate after aging | Mulch film Type I anti-aging: Longitudinal rupture nominal strain retention rate ≥50%; greenhouse film type after artificial aging tensile strength retention rate ≥70%, elongation at break ≥70% | Artificial accelerated aging GB/T 16422.2 (xenon arc lamp) / GB/T 16422.3 (fluorescent UV), tensile comparison before and after testing | Becomes brittle after one or two years outdoors, and breaks with a pull | Increase in weathering system Dispersion control |
| Carbon black content | ≥2.0% (General quantitative measure for dark-colored outdoor polyolefins) | According to JT/T 1432.1-2022 geogrid Class A caliber reference; carbon black content testing | Light-colored parts are ineffective with carbon black; for dark-colored parts, carbon black agglomerates should be broken first. | Carbon black has a small particle size and uniform dispersion; for light-colored parts, switch to HALS UV absorbers |
| UV resistance retention rate | Outdoor polyolefin reference ≥90% (Grade A geogrid aperture) | JT/T 1432.1-2022 | Intensity rapidly decreases with sunlight | HALS Carbon Black Synergy |
| Low-temperature shock / Low-temperature stretching | By region: does not break at −20℃, maintains stretchability | GB/T 1040.3 (Film) / GB/T 1043.1 (Impact) | Northern winter net/rope snaps easily | EVA/POE toughening compound |
| Light transmittance and haze (if involving greenhouse films) | Light transmittance is determined per piece (anti-aging greenhouse film ≥80%); haze is according to shading requirements. | GB/T 2410-2008 | Light transmittance degradation, yellowing | Light-colored/transparent parts follow the HALS system, without relying on carbon black |
| Pesticide-resistant / Performance retained after sulfur fumigation | Item Variation Threshold Method (Industry Comparison of Mechanical Retention After Exposure) | Conduct stretching and appearance comparison after simulated spraying/fumigation (Class B industry method) | HALS is deactivated by sulfur/acidic pesticides, causing its lifespan to drop sharply | Use pesticide-tolerant HALS, or reduce exposure |
Text version conclusion: There are three 'key points' in this table worth remembering—carbon black ≥2.0% is the quantitative bottom line for dark outdoor parts (borrowing the standard of A-grade geogrids); the retention rate of mechanics after aging is the strict criterion for lifespan; and the retention rate against pesticides/fumigation is the easiest to overlook. The latter two do not have unified mandatory industry thresholds, but for any parts used frequently around greenhouses with pesticides/sulfur, separate validation is necessary; otherwise, the field lifespan may be significantly worse than what you measured in the lab.
5. Common Failures and Root Causes: Relying solely on carbon black for weather resistance is one-sided; adding too much toughening agent will make the film soft and sag.
Failure 1: Only adding carbon black for weather resistance—light-colored parts will still fail first. Carbon black provides physical shielding and blocks UV effectively, but it only works for dark/black parts. For light-colored, green, or transparent agricultural parts, adding carbon black either causes discoloration due to light blocking or simply has no effect. What's even worse is that if carbon black is not well dispersed, the aggregated spots themselves become stress concentration points, causing the coating to crack first at these points—weather resistance fails to be achieved, and instead, seeds of failure are planted.
Failure 2: Too much toughening agent added, causing the film to become soft and sag, unable to stretch tight. This is the most common mistake in agricultural films. Adding EVA/POE improves flexibility and low-temperature impact resistance, but at the same time reduces tensile strength and rigidity. The mesh/film loses stiffness, sags after tensioning, and flaps and wears when blown by the wind. More is not necessarily better; it should be balanced according to the region and load.
Failure 3: HALS is quietly destroyed by pesticides and sulfur fumigation. This is a pitfall specific to agricultural scenarios. HALS (hindered amine light stabilizers) remove free radicals, but they are rapidly deactivated by sulfur fumigation and sulfur/halogen-containing compounds in acidic pesticides. In greenhouses where spraying and fumigation are regularly done, ordinary HALS cannot withstand their nominal lifespan. The solution is pesticide-resistant HALS or reducing the direct exposure of components to fumigation.
Failure Four: The mechanical retention after aging was not measured, only the initial strength was checked. Strong initial tensile strength does not mean it will still be strong after two years. For agricultural films and similar products, if only the factory strength is tested and the retention rate after aging is not checked, there is a high probability that it will break after just one season on-site. If the criteria are chosen incorrectly, all subsequent work is wasted.
6. Verification sequence: first appearance and light transmission, then mechanical properties after aging, but just return to the previous level.
Few peers write this part, but it is key to whether changing materials can save money. If the order is wrong, problems will explode at the final step.
`
① Appearance and light transmission (if involving greenhouse film/canopy or shading net)
Check whether color difference, blackout rate, and haze are within the threshold
↓ If this step fails, the following steps do not need to be done
② Mechanical Retention Rate After Aging
Artificial accelerated aging (GB/T 16422.2 / 16422.3) → Measure tensile/tear retention rate
↓ If this level is not passed, the item cannot be used directly and must be returned to the recipe.
③ Low-temperature performance
Tensile and impact at −20℃ (or local extreme values), specimen condition determined according to the standard
↓ However, revert to toughening system balancing
④ Pesticide-resistant / Fumigation-resistant
Perform mechanical and appearance comparison after simulated spraying/fumigation
↓ However, return to the stabilizer system (switch to pesticide-tolerant HALS)
⑤ Full-sheet Tensioning and Wind Load Trial Installation
Machine tensioning and simulated wind load striking
↓ However, return orientation/shrinkage/roll-up parameters
`
Every step has clear 'just go back to the previous level' criteria. The most common mistake is skipping ② and ④ and going straight to ⑤—using the finished product to judge weather resistance, only to find after a season on site that the aging retention rate didn't pass, and the cost has already been spent.
Text Version Conclusion: The verification sequence is appearance/transmittance → aging retention rate → low temperature → pesticide resistance → trial assembly. The aging retention rate and pesticide resistance stages must be completed before trial assembly because they are the decisive factors for whether the part can survive a season. Only after passing these should molding and assembly be discussed, so as not to waste trial production costs.
7. Reverse honesty section: For ultra-high transparency, ultra-long lifespan, or direct contact with fresh food, this part should not use modified PP.
Earlier, we talked about 'how to do it'; here, we talk about 'when not to do it.' This section is the most valuable for making choices.
| The situation that occurred | Why modified PP is not suitable | Which way should I go? |
|---|
| Requires extremely high light transmittance (high-end multi-span greenhouses, high-light-efficiency crops) | PP optics and flexibility are not the optimization directions for this type of cover film itself; the mainstream is high-transparency PE/EVA systems. | Use EVA/PO long-lasting high-transmittance greenhouse film |
| Requires ultra-long lifespan (over 5 years) long-lasting agricultural film | The long-lasting covering film body relies on the PE/EVA multilayer co-extrusion system, and PP is not used for the covering film body. | PE/EVA multi-layer co-extruded long-lasting film |
| Fresh food packaging/post-harvest for direct food contact | This type uses food-grade PE, compliant with GB 4806 for food contact; PP is also not the mainstream for covering films. | Food-grade PE system, exceeds GB 4806 |
| Require fully biodegradable mulch film | GB/T 35795-2017 Degradable films must not contain olefin-based raw materials such as polyethylene or polypropylene | Fully biodegradable mulch film (aliphatic polyester type) |
The rule is very clear: whenever it comes to 'highly transparent coating film body, ultra-long-life coating film, direct contact with fresh food, fully degradable' and similar cases, modified PP should not be forced. When encountering such requirements, the approach is first to clarify the boundaries, and then discuss whether peripheral components can handle it—any orders forced through in the end will have to be reworked and returned.
8. Material Change Risk List: The forming window of membrane products is completely different from that of pipe injection molding.
Before deciding to try modifying PP for agricultural film products, it is recommended to go through this table first. The real concern of customers is often not performance, but 'Do I need to change my current process?'
| Items to move | What needs to be confirmed | What will happen if I don't do it? |
|---|
| Die temperature and melt temperature | Film/net extrusion is sensitive to the temperature window, and the ranges for PP and PE are different. | Broken strips, crystal spots, uneven thickness |
| Traction and Cooling | Film orientation is determined by stretching, and cooling rate determines crystallization and shrinkage. | Inconsistent thickness, unstable shrinkage, uneven curling |
| Rewinding tension | Uneven tension in film/mesh winding can cause stretching deformation and interlayer adhesion | Loose edges, exposed tendons, off-track during machine operation |
| Orientation and Contraction | Film products have high strength in the oriented direction, low strength in the vertical direction, and anisotropic shrinkage. | Distortion after tensioning, wrinkling and cracking at the joints |
| Color difference | For dark parts, disperse the carbon black; for light parts, the color masterbatch batch needs to be matched on the color chart first. | Batch color difference disputes, light blockage rate drift |
| Verification order | Appearance/Light Transmittance → Aging Retention Rate → Low Temperature → Pesticide Resistance → Trial Installation | All the risks are concentrated to explode at the final step |
Text version conclusion: The forming window of film products is completely different from that of pipes and injection molding — what should be discussed first are 'orientation and shrinkage' and 'winding tension,' not mold shrinkage. Skipping aging and pesticide resistance verification and going straight to trial installation is equivalent to leaving the lifespan risk to only be exposed on-site after one season.
9. One-Page Report Comparison Table: Scenarios, Routes, Key Metrics, Verification Standards, Conditions to Confirm First
| Scene | Recommended Route | Key indicators | Verification Standard | Conditions that need to be confirmed first |
|---|
| Agricultural Insect-Proof Net / Shade Net | Weatherable PP (Carbon Black/HALS) Toughened by Region | Aging retention rate, shading rate, tear strength | GB/T 16422.2/16422.3; JT/T 1432.1-2022 (Carbon Black Caliber) | Color (dark/light), local UV intensity, whether pesticides are regularly sprayed in the greenhouse |
| Greenhouse Film Pressing Line / Binding Rope | Weather-resistant Toughened PP | Tensile strength, continuous at low temperature, UV resistance | GB/T 1040.3; GB/T 16422 series | Tensioning method, minimum operating temperature |
| PP-PE Composite Agricultural Waterproof Membrane | PP Reinforcement Layer PE Waterproof Layer | Stretching, stripping, aging retention | GB/T 16422 series; composite layer testing | Medium (pond/irrigation), whether it comes into contact with crops |
| Seedling Tray / Seedling Carrier | Food-contact grade weather-resistant PP | Rigidity, weather resistance, compliance | GB 4806 (if contacted); GB/T 16422 | Whether there is direct contact with seedlings/after harvest |
Text version conclusion: The purpose of this table is to allow technicians to report conclusions directly without having to reorganize their language. There is only one criterion for judgment—whether the client can determine the direction of the materials in one meeting using this table. If it cannot be determined, it is often because the two items 'how strong the local UV is' and 'whether to use sulfur' were not provided.
10. The part that is most likely to have problems is often not the material itself.
The most common early failure of agricultural film products is not insufficient initial strength, but brittleness, tearing, and discoloration after one or two seasons of outdoor use. Public information repeatedly emphasizes one point: the tertiary carbon chain of PP is extremely sensitive to ultraviolet light. Without a stabilizing system, its outdoor lifespan is measured in quarters; with carbon black (about 2-2.5%) or HALS (activity about 0.5%-2.5%), the lifespan can be extended to the level of several years.
The material requirements threshold is divided into two categories per item: for dark-colored structures/rope and net components, look at the carbon black content (≥2.0% is the general quantifiable reference for outdoor polyolefins) and UV resistance retention (refer to Class A geogrids ≥90% standard); for light-colored/light-adjustable parts, carbon black cannot be relied upon, and a HALS UV absorber system must be used, with additional verification of retention after pesticide/sulfur fumigation — because ordinary HALS can be quietly deactivated by sulfur/halogen-containing pesticides.
The industry practice is to balance the weathering system (carbon black/HALS/UV absorbers) and the toughening system (EVA/POE) according to region and load, rather than adding just one component. If this balance is not achieved, the material will either crack first or soften first on-site.
Ningbo Kolon New Materials Co., Ltd. commonly supplies modified polypropylene (PP) particles in this area, focusing on weather resistance and toughening: according to the exposure environment of agricultural parts (ultraviolet intensity, whether pesticides are sprayed in greenhouses, minimum usage temperature), they provide the corresponding grade of base material and stabilizer/toughening system. This is mainly used to address the two issues mentioned above: 'becoming brittle after one or two seasons outdoors' and 'the film becomes soft and saggy when too much toughening is added.' The formulation can be adjusted according to the working conditions of the parts and can be accompanied by small sample comparisons and aging tests. They can also handle the demand for multiple varieties of small batch agricultural parts.
| Operating condition | Key criterion | Cologne regular supply |
|---|
| Agricultural Insect-Proof Net / Shade Net | Mechanical retention rate after aging; light-colored parts use the HALS system | Weather-resistant modified PP, equipped with stabilizers according to the exposure environment |
| Greenhouse film pressing line / Binding rope | Continuous low temperature, UV resistant | Weather-resistant toughened PP orientation |
| Seedling Tray / Seedling Carrier | Food contact compliance, weather resistance | Food Contact Grade Weather-Resistant PP Orientation |
A reminder: when problems occur with agricultural parts, the most common mistake is changing the material first. Brittleness, color change, tearing—each issue has more than one cause: it could be that the stabilizer system is not balanced, the pesticide deactivates HALS, or excessive toughening causes softness and collapse. Identify the cause first, then change the material; if the order is reversed, even after several replacements, you may still be stuck at the same point.
Common Q&A
Q: Can the main body of agricultural film (mulch film/greenhouse film) be made directly from PP?
A: Mainstream practices say no. The standard for mulch film GB 13735-2017 specifies polyethylene as the base material, and greenhouse film as PE (GB/T 4455-2019) or EVA (GB/T 20202-2019) systems. PP is more suitable for peripheral agricultural film components—such as insect nets, shade nets, film pressing lines, composite waterproof membranes, and seedling carriers. The main body of covering film requires high transparency and flexibility, where PP is not advantageous.
Q: Can light-colored shade nets be made weather-resistant by adding carbon black?
A: No, or rather, it is not cost-effective. Carbon black provides physical shielding, only protecting dark/black items; adding it to light-colored parts will either cause color change and shading rate drift, or have no effect at all. Light-colored parts should use a HALS + UV absorber system, and the retention rate after pesticide/sulfur fumigation must be separately verified.
Q: Is adding more toughening agent the better for durability?
A: No. Excess EVA/POE increases flexibility and low-temperature impact resistance, but tensile strength and rigidity decrease at the same time. The film/net will become soft and sag, cannot be stretched tight, and will flap and wear in the wind. Proper balance according to region and load is the correct approach; only northern winter parts need higher toughening.
Q: Will pesticide application or greenhouse fumigation undo weather resistance?
A: Yes, and this is one of the easiest things to overlook for agricultural parts. Ordinary HALS can be rapidly deactivated by sulfur fumigation or sulfur/halogen compounds in acidic pesticides, resulting in a service life shorter than laboratory measurements. Peripheral parts of greenhouses that frequently use pesticides or sulfur must have separate pesticide/fumigation resistance verification, and consider pesticide-resistant HALS.
About Us
We stand between resin manufacturers and injection molding factories.
The previous stage is petrochemical and polymerization, the next stage is mold and machine. The middle part is most like translation—translating resin indicators into part performance, and part requirements back into material direction.
Ningbo Cologne New Materials Co., Ltd. produces modified polypropylene (PP) granules, covering homopolymer / random copolymer / impact copolymer grades, as well as modifications such as filled, glass fiber reinforced, toughened, flame retardant, low odor/low VOC, weather-resistant, scratch-resistant without coating; also trading in PP resins, secondary materials, and bulk materials from major petrochemical manufacturers.
